May 2017, The International Conference of Korean Society of Food Science of Animal Resources and 49th Annual Meeting, Postar award　　　　　　　　　　　　　　　
Ingestion of skim milk cheese modulates bile acid metabolism and cholic acid-induced disorders in rats
ISHIZUKA Satoshi

Nov. 2015, 6th International Conference on Food Factors, Postar award　　　　　　　　　　　　　　　
Isomaltomegalosaccharides modulation rat macrophage functions in primary culture and cytokine expression in rat intestinal mucosa
ISHIZUKA Satoshi

Nov. 2011, International Society for Nutraceuticals and Functional Foods, Poster award　　　　　　　　　　　　　　　
Dietary influence of linear α-1,6-polysaccharides on several parameters under experimental colitis depends on degree of the polymerization

May 2003, 日本栄養・食糧学会, 奨励賞　　　　　　　　　　　　　　　
消化管上皮の恒常性維持に関する基礎的研究
石塚 敏, Japan

Overexpression of GDE1 decreases glycerophosphoinositol in intestinal epithelial cells in vivo.
Siyi Chen, Rahmawati Aisyah, Ayako Honda, Takahiro Kudo, Yusuke Sotomaru, Satoshi Ishizuka, Thanutchaporn Kumrungsee, Toshihiko Iwanaga, Noriyuki Yanaka
Bioscience, biotechnology, and biochemistry, 89, 9, 1312, 1319, 2025, [Peer-reviewed], [International Magazine]
English, Scientific journal, Glycerophosphoinositol (GPI), a product of phospholipases acting on membrane phosphoinositides, is increasingly being recognized as an important bioactive molecule. However, its cellular functions in vivo remain unexplored. Recently, several mammalian glycerophosphodiesterases (GDEs) have shown to be involved in the catabolism of GPI, possibly regulating its intracellular levels. Given the growing interest in the biological significance of GPI in intestinal epithelial cells, this study focused on screening a GDE involved in intracellular GPI metabolism. Our results showed that GDE1 mRNA was highly expressed in intestinal epithelial cells and that its overexpression decreased intracellular GPI in cultured cells. We then created transgenic mice with GDE1 overexpression specifically in intestinal epithelial cells. These mice showed that GDE1 protein is localized in epithelial cells and that GPI levels are downregulated in the colon epithelial layers. This study provides a novel animal model for exploring GPI functions in vivo.

A cholic acid-supplemented diet suppresses very-low-density lipoprotein secretion in rats in the presence of insulin
Fumika Yokoyama, Satoshi Tsuyama, Satoshi Ishizuka
Bioscience, biotechnology, and biochemistry, 89, 7, 1045, 1049, 2025, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, We investigated whether dietary supplementation with cholic acid (CA) suppressed hepatic very-low-density lipoprotein (VLDL) secretion in rats. Dietary CA supplementation suppressed VLDL secretion in vivo in the presence of insulin. These results suggest that enterohepatic 12-hydroxylated bile acids further enhance insulin-induced suppression of hepatic VLDL secretion, which contributes to hepatic lipid accumulation.

A combination of dietary cholesterol and cholic acid induces hepatic expression of proinflammatory genes accompanied by changes in sterol metabolism and redox status.
Wakana Iwasaki, Hinata Soma, Hiromichi Yamazaki, Bokun Zhang, Yohei Fukami, Yasutake Tanaka, Masao Sato, Megumi Nishimukai, Satoshi Ishizuka
Drug metabolism and disposition: the biological fate of chemicals, 53, 7, 100095, 2025, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, Oxidized sterols and redox status play an important role in the enhancement of lipid accumulation and exacerbation of symptoms in the liver. In this study, we examined whether the combination of dietary supplementation with cholesterol (Chol) and cholic acid (CA) modulates sterol metabolism and factors related to lipid accumulation in the liver. C57BL/6J male mice (4-week-old) were fed diets containing Chol at 3 g/kg and/or CA at 0.5 g/kg for 6 weeks. The lipid parameters, sterol metabolism, and hepatic gene expression were analyzed. An increase in hepatic triglyceride and fatty acid concentrations was observed in mice fed the Chol-supplemented diets. No additional effect of CA supplementation was observed on triglyceride concentration in the liver. Chol supplementation enhanced the fecal excretion of β-muricholic acid, whereas CA supplementation enhanced the circulation of enterohepatic 12-hydroxylated bile acids. Notably, the combination of dietary Chol and CA supplementation synergistically increased the concentrations of 4β-hydroxycholesterol and the gene expression of some inflammation-related factors in the liver. Similar changes were observed in the expression of ATP-binding cassette transporters (Abcg5 and Abcg8). The hepatic concentrations of some oxysterols, including 4β-hydroxycholesterol, were correlated with the expression of ATP-binding cassette transporters and glutathione S-transferases (Gsta1 and Gstm1). This suggests that the combination of dietary Chol and CA supplementation synergistically enhances Chol oxidation and proinflammatory events, accompanied by an alteration in the redox balance in the liver of mice, which may be an early symptom of liver disorders. SIGNIFICANCE STATEMENT: This study revealed that a combination of dietary cholesterol (Chol) and cholic acid (CA) supplementation synergistically increased oxysterol concentrations, muricholic acid excretion, and the expression of genes for inflammatory responses and Chol transport-related factors in the mouse liver. Chol increased the ratio of reduced glutathione/oxidized glutathione in the liver, whereas this ratio was modulated in combination with CA. This study highlights individual and synergistic roles of Chol and CA in Chol oxidation, bile acid metabolism, and inflammatory responses in the liver.

Dietary Isomaltomegalosaccharides Ameliorate Lipopolysaccharide-induced Endotoxemia in Rats
Ga-Hyun Joe, Shota Hori, Akari Takeuchi, Sena Ishikawa, Kanta Pora, Fumika Yokoyama, Takahisa Iizuka, Yoshinori Fujimoto, Weeranuch Lang, Atsuo Kimura, Hiroshi Hara, Satoshi Ishizuka
Food Science and Technology Research, 31, 3, 279, 285, Japanese Society for Food Science and Technology, 2025, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Bile acid is a responsible host factor for high-fat diet-induced gut microbiota alterations in rats: proof of the "bile acid hypothesis".
Masamichi Watanabe, Yuki Fujita, Masahito Hagio, Satoshi Ishizuka, Yoshitoshi Ogura, Tetsuya Hayashi, Satoru Fukiya, Atsushi Yokota
Bioscience of microbiota, food and health, 44, 2, 110, 121, 2025, [Peer-reviewed], [Domestic magazines]
English, Scientific journal, High-fat diet (HFD)-induced alterations in gut microbiota may be associated with host pathophysiology, prompting increased interest in elucidating their causal relationships. However, the mechanisms by which HFDs induce these alterations require further clarification. Our previous study using cholic acid (CA)-fed rats suggested that bile acid drives the HFD-induced microbiota alterations as a host factor, a concept termed the "bile acid hypothesis". We analyzed the alterations in the cecal microbiota and bile acid composition in HFD-fed rats and compared the results with those of rats on a CA-supplemented diet. In both cases, the concentrations of total bile acids, including highly bactericidal deoxycholic acid (DCA), increased, concomitant with the increases in the Firmicutes (Bacillota)/Bacteroidetes (Bacteroidota) ratio. Operational taxonomic units (OTUs), accounting for 63.39% of the cecal microbiota of control rats, showed a significant correlation with the total bile acid concentration in HFD-fed rats. A DCA sensitivity test conducted in Firmicutes isolates, corresponding to the predominant OTUs from the HFD-fed rats, exhibited significantly higher DCA resistance compared with Bacteroidetes. The top 12 most abundant OTUs of Firmicutes and Bacteroidetes showing positive or negative correlations with the total bile acid concentration were selected from the HFD-fed rats, and their dynamics were compared with those in the CA-fed rats. Of the 24 OTUs, 18, which constituted 48.28% of the cecal population in the control rats, were altered in the same direction (increase or decrease) in the HFD- and CA-supplemented diet groups. Therefore, approximately half of the cecal populations in the control rats were affected by bile acids, substantiating the bile acid hypothesis microbiologically and quantitatively.

Quantitative analysis of sterol balance in a mouse model of hepatic lipid accumulation induced by cholesterol and cholic acid supplementation
Hinata Soma, Ryo Yoshida, Satoshi Ishizuka
Bioscience, Biotechnology, and Biochemistry, 89, 3, 438, 445, Oxford University Press (OUP), 2025, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal, Abstract

The cholesterol balance and bile acid metabolism in a mouse model of hepatic lipid accumulation induced by a diet supplemented with cholesterol and cholic acid (CA) were quantitatively evaluated. The mice were fed diets supplemented with different levels of cholesterol (0, 3, or 6 g/kg of diet) and CA (0.5 g/kg of diet) for 6 weeks. Cholesterol supplementation doubled the hepatic triglyceride concentration, regardless of the supplementation level, without inflammation or gallstone formation. Both cholesterol supplementations enhanced fecal excretion of muricholic acid. Additionally, the higher cholesterol supplementation led to an increase in fecal cholesterol excretion, accompanied by elevated expression of hepatic cholesterol exporters and a reduction in fecal bile acid excretion. In this mouse study, supplementation with 3 g cholesterol/kg diet and 0.5 g CA/kg diet was sufficient to induce hepatic lipid accumulation.

Comparative Analysis of γ-Cyclodextrin, Perilla Oil, and Their Inclusion Complexes on Liver Injury and Dyslipidemia Associated with Elevated Gastrointestinal 12-Hydroxylated Bile Acid Levels.
Keisuke Yoshikiyo, Hidehisa Shimizu, Edward G Nagato, Satoshi Ishizuka, Tatsuyuki Yamamoto
Molecules (Basel, Switzerland), 30, 2, 281, 2025, [Peer-reviewed], [International Magazine]
English, Scientific journal, Our previous study demonstrated that γ-cyclodextrin (γ-CD)-perilla oil inclusion complexes increase plasma α-linolenic acid and eicosapentaenoic acid levels in healthy rats without adverse effects. The present study examined the effects of perilla oil, γ-CD, and their inclusion complexes on rats fed cholic acid (CA) to mimic the elevated gastrointestinal 12-hydroxylated (12OH) bile acid levels in high-fat diet-fed rats. Rats fed CA (CA group) tended to have higher AST, ALT, plasma total cholesterol (T-CHO), and triglyceride (TG) levels compared to controls fed a standard diet without CA. Rats fed CA and perilla oil (CA+LP group) showed a tendency for lower AST and plasma TG levels than those in the CA group. Rats fed CA and γ-CD (CA+CD group) had significantly higher AST, ALT, plasma T-CHO, and TG levels than the controls, indicating severe liver injury and dyslipidemia. Rats fed CA and the γ-CD-perilla oil inclusion complex (CA+IC group) had significantly lower AST and ALT levels than the CA+CD rats, with a trend towards lower plasma T-CHO and TG levels. Plasma α-linolenic acid and eicosapentaenoic acid levels were significantly higher in the CA+LP and CA+IC groups than in the controls and CA+CD groups. However, the CA+IC group tended to have lower α-linolenic acid levels and significantly lower eicosapentaenoic acid levels than the CA+LP group. This suggests an accelerated conversion of α-linolenic acid to eicosapentaenoic acid in the CA+IC group, which may contribute to the attenuation of liver injury and dyslipidemia. These findings suggest that γ-CD may exacerbate liver injury and dyslipidemia caused by elevated gastrointestinal 12OH bile acid levels, whereas γ-CD-perilla oil inclusion complexes may ameliorate these effects by altering fatty acid metabolism. Furthermore, we recommend evaluating γ-CD safety in both healthy and pathological models and carefully selecting compounds co-ingested with γ-CD.

Dietary supplementation with cholic acid reduces insulin secretion in response to intraperitoneal glucose administration in rats
Fumika Yokoyama, Reika Yoshitsugu, Hiromichi Yamazaki, Satoshi Ishizuka
Journal of Nutritional Science and Vitaminology, 70, 1, 76, 81, 2024, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Differences in iron balance observed with dietary cholic acid supplementation and marginal iron deficiency in rats.
Natsuki Kubota, Shota Hori, Satoshi Ishizuka
Bioscience, biotechnology, and biochemistry, 88, 1, 79, 85, 19 Dec. 2023, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, We investigated whether a cholic acid (CA)-supplemented diet and marginal iron deficiency (MID) diet influence hepatic lipid accumulation and iron balance in rats for 2 weeks. The CA diet enhanced hepatic lipid accumulation and modulated iron metabolism such as enhancement of fecal iron excretion, reduction in iron absorption, and no alteration in plasma iron levels. The MID diet did not alter hepatic lipid concentrations with reduced iron concentration in the liver and plasma. In combination, influence of the CA supplementation on the hepatic iron concentration was opposite between iron-sufficient and MID conditions. In the liver, the CA diet enhanced lipocalin 2 expression, whereas the MID diet enhanced transferrin receptor 1 expression and reduced hepcidin expression. This study revealed an involvement of 12-hydroxylated bile acids in regulation of hepatic iron concentration under MID condition.

An increase in enterohepatic 12-hydroxylated bile acid circulation and presymptomatic disorders　　　　　　　　　　　　　　　
Satoshi Ishizuka
Precision Medicine, 6, 14, 78, 81, Dec. 2023, [Invited], [Lead author, Corresponding author], [Domestic magazines]
Japanese, Scientific journal

White adipose tissue undergoes browning during preweaning period in association with microbiota formation in mice.
Anju Tsukada, Yuko Okamatsu-Ogura, Emi Futagawa, Yuki Habu, Natsumi Takahashi, Mira Kato-Suzuki, Yuko Kato, Satoshi Ishizuka, Kei Sonoyama, Kazuhiro Kimura
iScience, 26, 7, 107239, 107239, 21 Jul. 2023, [Peer-reviewed], [International Magazine]
English, Scientific journal, Beige adipocytes are transiently induced during early postnatal period in mice. Previous studies have suggested that, unlike in adults, the induction is independent of the sympathetic nerve activity; however, the mechanism is yet unknown. Here, we showed that beige adipocytes are induced during the preweaning period in association with the formation of microbiota in mice. Alteration of gut microbiota composition in preweaning mice by maternal treatment with antibiotics or high-fat diet feeding substantially suppressed WAT browning. The suppression was also found in pups transplanted cecal microbiota from pups of high-fat diet-fed dams. These treatments reduced the hepatic expression of genes involved in bile acid synthesis and the serum bile acids level. The abundance of Porphyromonadaceae and Ruminococcaceae in microbiota showed a positive and negative correlation with the induction of beige adipocytes, respectively. This finding may provide comprehensive understanding of the association between gut microbiota and adipose tissue development in the neonatal period.

Supplementary effect of whey components on the monascin productivity of Monascus sp.
Qingyun Huang, Nodoka Miyaki, Zongfei Li, Yutaroh Takahashi, Satoshi Ishizuka, Toru Hayakawa, Jun-Ichi Wakamatsu, Haruto Kumura
Journal of the science of food and agriculture, 103, 8, 4234, 4241, Jun. 2023, [Peer-reviewed], [International Magazine]
English, Scientific journal, BACKGROUND: Monascus sp. has been used in fermented foods for centuries. It can synthesize yellow, red, and orange pigments as secondary metabolites. Here, we focused on yellow pigment monascin, responsible for anti-inflammation and antidiabetic effects, and investigated whether whey could be a suitable substrate with or without rice powder for monascin production using M. purpureus AHU 9085, M. pilosus NBRC 4520 and M. ruber NBRC 32318. RESULTS: The growth and monascin production of the three Monascus strains were dependent on three liquid media consisting of whey and/or rice. All strains showed the best growth in a rice and whey mixed medium, in which M. ruber NBRC 32318 exhibited the highest total monascin production. Subsequent investigation of the effects of whey components indicated that a mineral cocktail in whey was particularly effective in stimulating the monascin production efficiency of M. ruber NBRC 32318. However, this recipe exhibited less stimulation, or even inhibition, for M. pilosus NBRC 4520 and M. purpureus AHU 9085, respectively. In terms of total monascin production, rice with whey provided the highest amount due to growth promotion along with relatively high production efficiency. CONCLUSION: The effect of whey on growth and monascin production was strongly dependent on the Monascus strains. Even a mineral cocktail in whey could regulate monascin productivity in a strain-specific manner. Further studies are needed to elucidate the mechanism behind the diverse responses by the minerals in the production of monascin from Monascus. © 2023 Society of Chemical Industry.

Ingesting a fermented milk product reduces liver triacylglycerol accumulation and normalizes gut permeability in rats even under a cholic acid-fed condition
DongGeun Lee, Wakana Iwasaki, Shota Hori, Natsuki Kubota, Satoshi Ishizuka
Journal of Functional Foods, 104, 105523, 105523, Elsevier BV, May 2023, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
Scientific journal

Metabolic alterations of the gut-liver axis induced by cholic acid contribute to hepatic steatosis in rats.
Hongxia Liu, Fumika Yokoyama, Satoshi Ishizuka
Biochimica et biophysica acta. Molecular and cell biology of lipids, 159319, 159319, 17 Apr. 2023, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, 12α-Hydroxylated (12αOH) bile acids (BAs) selectively increase with high-fat diet intake. Dietary supplementation with cholic acid (CA) in rats is a possible strategy to reveal the causal link between 12αOH BAs and hepatic steatosis. The present study aimed to investigate the metabolic mechanism underlying the effect of 12αOH BAs on hepatic steatosis. Male WKAH rats were fed either a control (Ct) or CA-supplemented diet (0.5 g/kg). After the 12-week intervention, the CA diet elevated the 12αOH BA levels in the gut-liver axis. CA-fed rats showed greater hepatic lipid accumulation than in the Ct group, regardless of the dietary energy balance. Untargeted metabolomics suggested marked differences in the fecal metabolome of rats subjected to the CA diet compared with that of Ct, characterized by the depletion of fatty acids and enrichment of amino acids and amines. Moreover, the liver metabolome differed in the CA diet group, characterized by an alteration in redox-related pathways. The CA diet elevated nicotinamide adenine dinucleotide consumption owing to the activation of poly(ADP-ribose) polymerase 1, resulting in impaired peroxisome proliferator-activated receptor α signaling in the liver. The CA diet increased sedoheptulose 7-phosphate, and enhanced glucose-6-phosphate dehydrogenase activity, suggesting promotion of the pentose phosphate pathway that generates reducing equivalents. Integrated analysis of the gut-liver metabolomic data revealed the role of deoxycholic acid and its liver counterpart in mediating these metabolic alterations. These observations suggest that alterations in metabolites induced by 12αOH BAs in the gut-liver axis contribute to the enhancement of liver lipid accumulation.

A diet supplemented with cholic acid elevates blood pressure accompanied by albuminuria in rats
Tomoko Shimoda, Hidehisa Shimizu, Wakana Iwasaki, Hongxia Liu, Yoshie Kamo, Koji Tada, Taketo Hanai, Shota Hori, Ga-Hyun Joe, Yasutake Tanaka, Masao Sato, Hitoshi Miyazaki, Satoshi Ishizuka
Bioscience, Biotechnology, and Biochemistry, 87, 4, 434, 441, Oxford University Press (OUP), 2023, [Peer-reviewed], [Last author, Corresponding author]
Scientific journal, Abstract

A diet supplemented with cholic acid (CA), the primary 12α-hydroxylated bile acid, can induce hepatic lipid accumulation in rats without obesity. This study examined the effects of a CA-supplemented diet on blood pressure (BP). After acclimation, WKAH/HkmSlc rats (3 week old) were divided into two groups and fed with a control AIN-93-based diet or a CA-supplemented diet (0.5 g CA/kg) for 13 weeks. The CA diet increased systolic and diastolic BP as well as hepatic lipid concentrations in the rats. No changes were found in the blood sodium concentration. Urinary albumin concentration increased in CA-fed rats. An increase was observed in the hepatic expression of ATP binding cassette subfamily B member 1B that correlated BPs and urinary albumin concentration accompanied by an increase in portal taurocholic acid concentration. These results suggest that 12α-hydroxylated bile acids are involved in increased BP and albuminuria via alteration of hepatic function.

Comparison of metabolism and circulation of 12α-hydroxylated bile acids in response to a high-fat diet　　　　　　　　　　　　　　　
Satoshi Ishizuka, Wakana Iwasaki
アグリバイオ, 6, 14, 60, 63, Dec. 2022, [Invited], [Lead author, Corresponding author], [Domestic magazines]
Japanese, Scientific journal

The ratio of 12α to non-12-hydroxylated bile acids reflects hepatic triacylglycerol accumulation in high-fat diet-fed C57BL/6J mice.
Wakana Iwasaki, Ryo Yoshida, Hongxia Liu, Shota Hori, Yuki Otsubo, Yasutake Tanaka, Masao Sato, Satoshi Ishizuka
Scientific reports, 12, 1, 16707, 16707, Oct. 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, In our previous study, enterohepatic 12α-hydroxylated (12α) bile acid (BA) levels were found to be correlated with hepatic triacylglycerol concentration in rats fed high-fat (HF) diet. Since BA composition is diverse depending on animal species, we evaluated whether such a relationship is applicable in mice in response to an HF diet. C57BL/6JJmsSLC (B6) male mice were fed HF diet for 13 weeks and analyzed for triacylglycerol, cholesterol, oxysterols, and other metabolites in the liver. The BA composition was determined in the liver, small intestinal contents, portal plasma, aortic plasma, and feces. Neutral sterols were also measured in the feces. The ratio of 12α BA/non-12 BA increased in the liver, portal plasma, small intestinal contents, and feces of HF-fed B6 mice. Moreover, a positive correlation was observed between the ratio of fecal 12α BAs/non-12 BAs and hepatic triacylglycerol concentration. The concentration of 7α-hydroxycholesterol was increased in the liver of HF-fed B6 mice, whereas no increase was observed in the hepatic expression of cytochrome P450 family 7 subfamily A member 1. The present study showed that the ratio of 12α BA/non-12 BA in feces is closely associated with hepatic triacylglycerol accumulation in B6 mice fed HF diet.

生活習慣病の発症と12α水酸化胆汁酸：肝脂質蓄積と消化管バリア　　　　　　　　　　　　　　　
石塚 敏
Microbiome Science, 1, 1, 24, 29, Jul. 2022, [Invited], [Lead author, Corresponding author], [Domestic magazines]
Japanese, Scientific journal

Taurocholic acid, a primary 12α-hydroxylated bile acid, induces leakiness in the distal small intestine in rats.
Hongxia Liu, Ohji Kohmoto, Ayana Sakaguchi, Shota Hori, Misuzu Tochigi, Koji Tada, Yeonmi Lee, Keidai Kikuchi, Satoshi Ishizuka
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 165, 113136, 113136, Jul. 2022, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, A high-fat diet increases 12α-hydroxylated (12αOH) bile acid (BA) secretion in rats, and secondary BAs are responsible for the leaky gut. This study aimed to examine the role of primary 12αOH BAs in gut barrier impairment in rats using dietary cholic acid (CA) supplementation (0.5 g/kg diet). The CA diet increased the 12αOH BAs concentrations in the small and large intestine, accompanied by gut barrier impairment. Based on the luminal 12αOH BAs concentrations, ex vivo gut leakiness was determined. Deoxycholic acid increased permeability in the large intestine, whereas taurocholic acid (TCA) increased the ileal permeability, but not jejunal permeability. A Rho kinase inhibitor attenuated TCA-induced ileal permeability. Administration of vancomycin, which abolishes secondary BAs, did not influence the gut leakiness induced by the CA diet. Changes in the gut permeation marker in the tail vein blood suggested the possibility that the CA-induced leakiness occurred in the small intestine. The CA diet enhanced the phosphorylation of myosin light chain 2 and reduced claudins expressions in rat ileal epithelia. Reductions in barrier function-related genes were observed in the ileum, but not in the colon of the CA-fed rats. Overall, the present study demonstrated the significance of TCA in proximal gut leakiness.

Dietary supplementation with okara and Bacillus coagulans lilac-01 improves hepatic lipid accumulation induced by cholic acids in rats
Yeonmi Lee, Yasutake Tanaka, Wakana Iwasaki, Fumika Yokoyama, Ga-Hyun Joe, Misaki Tsuji, Takuma Nose, Koji Tada, Taketo Hanai, Shota Hori, Hidehisa Shimizu, Kimiko Minamida, Kazunori Miwa, Satoshi Ishizuka
Journal of Functional Foods, 90, 104991, 104991, Elsevier BV, Mar. 2022, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal

腸内での二次胆汁酸生成と腸内細菌叢変化・疾病の誘導　　　　　　　　　　　　　　　
吹谷 智, 横田 篤, 石塚 敏
機能性食品と薬理栄養, 15, 4, 229, 234, (株)インフォノーツパブリッシング, Feb. 2022, [Invited]
Japanese, Scientific journal

Dietary raffinose ameliorates hepatic lipid accumulation induced by cholic acid via modulation of enterohepatic bile acid circulation in rats.
Kenta Maegawa, Haruka Koyama, Satoru Fukiya, Atsushi Yokota, Koichiro Ueda, Satoshi Ishizuka
British journal of nutrition, 127, 11, 1621, 1630, 2022, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, Enterohepatic circulation of 12α-hydroxylated (12αOH) bile acid (BA) is enhanced depending on the energy intake in high-fat diet-fed rats. Such BA metabolism can be reproduced using a diet supplemented with cholic acid (CA), which also induces simple steatosis, without inflammation and fibrosis, accompanied by some other symptoms that are frequently observed in the condition of non-alcoholic fatty liver in rats. We investigated whether supplementation of the diet with raffinose (Raf) improves hepatic lipid accumulation induced by the CA-fed condition in rats. After acclimation to the AIN-93-based control diet, male Wistar rats were fed diets supplemented with a combination of Raf (30 g/kg diet) and/or CA (0·5 g/kg diet) for 4 weeks. Dietary Raf normalised hepatic TAG levels (two-way ANOVA P < 0·001 for CA, P = 0·02 for Raf and P = 0·004 for interaction) in the CA-supplemented diet-fed rats. Dietary Raf supplementation reduced hepatic 12αOH BA concentration (two-way ANOVA P < 0·001 for CA, P = 0·003 for Raf and P = 0·03 for interaction). The concentration of 12αOH BA was reduced in the aortic and portal plasma. Raf supplementation increased acetic acid concentration in the caecal contents (two-way ANOVA P = 0·001 as a main effect). Multiple regression analysis revealed that concentrations of aortic 12αOH BA and caecal acetic acid could serve as predictors of hepatic TAG concentration (R2 = 0·55, P < 0·001). However, Raf did not decrease the secondary 12αOH BA concentration in the caecal contents as well as the transaminase activity in the CA diet-fed rats. These results imply that dietary Raf normalises hepatic lipid accumulation via suppression of enterohepatic 12αOH BA circulation.

12α-Hydroxylated bile acid enhances accumulation of adiponectin and immunoglobulin A in the rat ileum.
Reika Yoshitsugu, Hongxia Liu, Yoshie Kamo, Akari Takeuchi, Ga-Hyun Joe, Koji Tada, Keidai Kikuchi, Nobuyuki Fujii, Shinri Kitta, Shota Hori, Manami Takatsuki, Hitoshi Iwaya, Yasutake Tanaka, Hidehisa Shimizu, Satoshi Ishizuka
Scientific reports, 11, 1, 12939, 12939, 21 Jun. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, We previously reported that dietary supplementation with cholic acid (CA), the primary 12α-hydroxylated (12αOH) bile acid (BA), reduces plasma adiponectin concentration in rats. The aim of this study was to examine the distribution of adiponectin in the body of CA-fed rats and its influence on mucosal immunoglobulin A concentration in the intestine. Rats were fed a diet supplemented with or without CA (0.5 g CA/kg diet) for 13 weeks. A reduction in plasma adiponectin level was observed from week 3. At the end of the experiment, the CA diet reduced plasma adiponectin concentration both in the portal and aortic plasma. Accumulation of adiponectin was accompanied by an increase in cadherin-13 mRNA expression in the ileal mucosa of CA-fed rats. No increase was observed in adiponectin mRNA expression in the ileal and adipose tissues of the CA-fed rats. Immunoglobulin A concentration in the ileal mucosa was elevated in the CA-fed rats and was correlated with the ileal adiponectin concentration. 12αOH BAs may modulate mucosal immune response that are involved in the accumulation of adiponectin in the ileum.

Primary 12α-Hydroxylated Bile Acids Lower Hepatic Iron Concentration in Rats.
Shota Hori, Minako Satake, Ohji Kohmoto, Ryo Takagi, Kazufumi Okada, Satoru Fukiya, Atsushi Yokota, Satoshi Ishizuka
The Journal of nutrition, 151, 3, 523, 530, 11 Mar. 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, BACKGROUND: Primary 12α-hydroxylated bile acids (12αOH BAs) enhance intestinal iron uptake due to their ability ex vivo to chelate iron. However, no information is available on their role in vivo, especially in the liver. OBJECTIVES: To investigate the effects and mechanisms of primary 12αOH BAs on hepatic iron concentration in vivo. METHODS: Male Wistar King A Hokkaido male rats (WKAH/HkmSlc) rats aged 4-5 weeks were fed a control diet or a diet with cholic acid (CA; 0.5 g/kg diet), the primary 12αOH BA, for 2 weeks (Study 1) or 13 weeks (Study 2). In Study 3, rats fed the same diets were given drinking water either alone or containing vancomycin (200 mg/L) for 6 weeks. The variables measured included food intake (Studies 1-3), bile acid profiles (Studies 1 and 3), hepatic iron concentration (Studies 1-3), fecal iron excretion (Studies 1 and 2), iron-related liver gene expression (Studies 2 and 3), and plasma iron-related factors (Studies 2 and 3). RESULTS: In Study 1, CA feed reduced the hepatic iron concentration (-16%; P = 0.005) without changing food intake or fecal iron excretion. In Study 2, we found a significant increase in the aortic plasma concentration of lipocalin 2 (LCN2; +65%; P < 0.001), an iron-trafficking protein. In Study 3, we observed no effect of vancomycin treatment on the CA-induced reduction of hepatic iron concentration (-32%; P < 0.001), accompanied by increased plasma LCN2 concentration (+72%; P = 0.003), in the CA-fed rats despite a drastic reduction in the secondary 12αOH BA concentration (-94%; P < 0.001) in the aortic plasma. CONCLUSIONS: Primary 12αOH BAs reduced the hepatic iron concentration in rats. LCN2 may be responsible for the hepatic iron-lowering effect of primary 12αOH BAs by transporting iron out of the liver.

栄養過多による12α水酸化胆汁酸の増加とラットにおける肥満を伴わない肝脂質蓄積　　　　　　　　　　　　　　　
石塚 敏
生化学, 93, 1, 43, 51, Feb. 2021, [Peer-reviewed], [Invited], [Lead author, Corresponding author]
Japanese, Scientific journal

12α-Hydroxylated bile acid induces hepatic steatosis with dysbiosis in rats.
Ja-Young Lee, Hidehisa Shimizu, Masahito Hagio, Satoru Fukiya, Masamichi Watanabe, Yasutake Tanaka, Ga-Hyun Joe, Hitoshi Iwaya, Reika Yoshitsugu, Keidai Kikuchi, Misaki Tsuji, Nanako Baba, Takuma Nose, Koji Tada, Taketo Hanai, Shota Hori, Akari Takeuchi, Yumiko Furukawa, Bungo Shirouchi, Masao Sato, Tadasuke Ooka, Yoshitoshi Ogura, Tetsuya Hayashi, Atsushi Yokota, Satoshi Ishizuka
Biochimica et biophysica acta. Molecular and cell biology of lipids, 1865, 12, 158811, 158811, 04 Sep. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, There is an increasing need to explore the mechanism of the progression of non-alcoholic fatty liver disease. Steroid metabolism is closely linked to hepatic steatosis and steroids are excreted as bile acids (BAs). Here, we demonstrated that feeding WKAH/HkmSlc inbred rats a diet supplemented with cholic acid (CA) at 0.5 g/kg for 13 weeks induced simple steatosis without obesity. Liver triglyceride and cholesterol levels were increased accompanied by mild elevation of aminotransferase activities. There were no signs of inflammation, insulin resistance, oxidative stress, or fibrosis. CA supplementation increased levels of CA and taurocholic acid (TCA) in enterohepatic circulation and deoxycholic acid (DCA) levels in cecum with an increased ratio of 12α-hydroxylated BAs to non-12α-hydroxylated BAs. Analyses of hepatic gene expression revealed no apparent feedback control of BA and cholesterol biosynthesis. CA feeding induced dysbiosis in cecal microbiota with enrichment of DCA producers, which underlines the increased cecal DCA levels. The mechanism of steatosis was increased expression of Srebp1 (positive regulator of liver lipogenesis) through activation of the liver X receptor by increased oxysterols in the CA-fed rats, especially 4β-hydroxycholesterol (4βOH) formed by upregulated expression of hepatic Cyp3a2, responsible for 4βOH formation. Multiple regression analyses identified portal TCA and cecal DCA as positive predictors for liver 4βOH levels. The possible mechanisms linking these predictors and upregulated expression of Cyp3a2 are discussed. Overall, our observations highlight the role of 12α-hydroxylated BAs in triggering liver lipogenesis and allow us to explore the mechanisms of hepatic steatosis onset, focusing on cholesterol and BA metabolism.

A low coefficient of variation in hepatic triglyceride concentration in an inbred rat strain.
Tomoko Shimoda, Shota Hori, Kenta Maegawa, Akari Takeuchi, Yeonmi Lee, Ga-Hyun Joe, Yasutake Tanaka, Hidehisa Shimizu, Satoshi Ishizuka
Lipids in health and disease, 19, 1, 137, 137, 16 Jun. 2020, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］, [International Magazine]
English, Scientific journal, BACKGROUND: Inbred strains are characterized by less genetic variation, which suggests usefulness of inbred strains for evaluations of various parameters. In this study, experimental reproducibility in several parameters was compared between an outbred Wistar rat and Wistar King A Hokkaido (WKAH/HkmSlc) rat, the inbred strain that is originated from Wistar rats. METHODS: Difference of variations was investigated in parameters of body compositions and liver functions such as body weight, liver weight, liver triglycerides (TG), liver cholesterol and plasma alanine aminotransferase activity (ALT) between WKAH rats and outbred Wistar rats by using the coefficient of variation (CV). RESULTS: There was no difference in the CVs of body weight and relative liver weight between WKAH and Wistar rats. The CVs of body weight and relative liver weight were below 10% in both WKAH and Wistar rats. The CVs of TG, cholesterol, and ALT in Wistar rats were between 30 and 40%, whereas those in WKAH rats were between 10 and 25%. A low CV level of TG was observed in WKAH rats compared to that in Wistar rats regardless of the duration of the experimental period in those rat strains. CONCLUSION: The low CV values in metabolic parameters involved in liver functions in the inbred rats suggested an advantage of using inbred rather than outbred rats for the evaluation of liver lipid metabolism.

Lithocholic acid increases intestinal phosphate and calcium absorption in a vitamin D receptor dependent but transcellular pathway independent manner.
Nobuhiro Hashimoto, Isao Matsui, Satoshi Ishizuka, Kazunori Inoue, Ayumi Matsumoto, Karin Shimada, Shota Hori, Dong Geun Lee, Seiichi Yasuda, Yusuke Katsuma, Sachio Kajimoto, Yohei Doi, Satoshi Yamaguchi, Keiichi Kubota, Tatsufumi Oka, Yusuke Sakaguchi, Yoshitsugu Takabatake, Takayuki Hamano, Yoshitaka Isaka
Kidney international, 97, 6, 1164, 1180, Jun. 2020, [Peer-reviewed], [International Magazine]
English, Scientific journal, Phosphate/calcium homeostasis is crucial for health maintenance. Lithocholic acid, a bile acid produced by intestinal bacteria, is an agonist of vitamin D receptor. However, its effects on phosphate/calcium homeostasis remain unclear. Here, we demonstrated that lithocholic acid increases intestinal phosphate/calcium absorption in an enterocyte vitamin D receptor-dependent manner. Lithocholic acid was found to increase serum phosphate/calcium levels and thus to exacerbate vascular calcification in animals with chronic kidney disease. Lithocholic acid did not affect levels of intestinal sodium-dependent phosphate transport protein 2b, Pi transporter-1, -2, or transient receptor potential vanilloid subfamily member 6. Everted gut sac analyses demonstrated that lithocholic acid increased phosphate/calcium absorption in a transcellular pathway-independent manner. Lithocholic acid suppressed intestinal mucosal claudin 3 and occludin in wild-type mice, but not in vitamin D receptor knockout mice. Everted gut sacs of claudin 3 knockout mice showed an increased permeability for phosphate, but not calcium. In patients with chronic kidney disease, serum 1,25(OH)2 vitamin D levels are decreased, probably as an intrinsic adjustment to reduce phosphate/calcium burden. In contrast, serum and fecal lithocholic acid levels and fecal levels of bile acid 7α-dehydratase, a rate-limiting enzyme involved in lithocholic acid production, were not downregulated. The effects of lithocholic acid were eliminated by bile acid adsorptive resin in mice. Thus, lithocholic acid and claudin 3 may represent novel therapeutic targets for reducing phosphate burden.

Association between 12α-hydroxylated bile acids and hepatic steatosis in rats fed a high-fat diet.
Shota Hori, Takayuki Abe, Dong Geun Lee, Satoru Fukiya, Atsushi Yokota, Nao Aso, Bungo Shirouchi, Masao Sato, Satoshi Ishizuka
The Journal of nutritional biochemistry, 83, 108412, 108412, 20 May 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, High-fat (HF) diet induces hepatic steatosis that is a risk factor for noncommunicable diseases such as obesity, type 2 diabetes and cardiovascular disease. Previously, we found that HF feeding in rats increases the excretion of fecal bile acids (BAs), specifically 12α-hydroxylated (12αOH) BAs. Although the liver is the metabolic center in our body, the association between hepatic steatosis and 12αOH BAs in HF-fed rats is unclear. Thus, we investigated extensively BA composition in HF-fed rats and evaluated the association between hepatic steatosis and 12αOH BAs. Acclimated male inbred WKAH/HkmSlc rats were divided into two groups and fed either control or HF diet for 8 weeks. Feeding HF diet increased hepatic triglyceride and total cholesterol concentrations, which correlated positively with 12αOH BAs concentrations but not with non-12αOH BAs in the feces, portal plasma and liver. Accompanied by the increase in 12αOH BAs, the rats fed HF diet showed increased fat absorption and higher mRNA expression of liver Cidea. The enhancement of 12αOH BA secretion may contribute to hepatic steatosis by the promotion of dietary fat absorption and hepatic Cidea mRNA expression. The increase in 12αOH BAs was associated with enhanced liver cholesterol 7α-hydroxylase (Cyp7a1) and sterol 12α-hydroxylase (Cyp8b1) mRNA expression. There was a significant increase in 7α-hydroxycholesterol, a precursor of BAs, in the liver of HF-fed rats. Altogether, these data suggest that the HF diet increases preferentially 12αOH BAs synthesis by utilizing the accumulated hepatic cholesterol and enhancing mRNA expression of Cyp7a1 and Cyp8b1 in the liver.

Untargeted lipidomic analysis of plasma from high fat diet-induced obese rats using UHPLC- linear trap quadrupole -Orbitrap MS.
Siddabasave Gowda B Gowda, Zi-Jun Gao, Zhen Chen, Takayuki Abe, Shota Hori, Satoru Fukiya, Satoshi Ishizuka, Atsushi Yokota, Hitoshi Chiba, Shu-Ping Hui
Analytical sciences, 36, 7, 821, 828, 17 Jan. 2020, [Peer-reviewed], [International Magazine]
English, Scientific journal, High-fat diet (HFD)-induced obesity is a primary risk factor for serious health problems. Although much research has been performed at the genomic level, lipidomic studies were limited. In this study, we aim to obtain a comprehensive profile of circulating plasma lipids, which are altered in rodent rat obesity by untargeted liquid chromatography-mass spectrometry. Rats fed with HFD for 8 weeks had increased body weight, liver and adipose tissue weight. The analysis results revealed that polyunsaturated fatty acids (PUFAs) and their corresponding phosphatidylcholine, phosphatidylinositol, and phosphatidylserine were significantly decreased in rats fed with HFD. In contrast, less unsaturated and ether type phosphatidylglycerols were increased. The triacylglycerides (TAGs) having saturated FA were increased in the HFD condition, whereas TAGs having PUFA were decreased. The levels of many plasma lipids were altered, and interestingly PUFA derived lipids were negatively associated with obesity. This signifies the importance of a PUFAs enriched diet to overwhelm obesity associated diseases.

Correlation between 12α-hydroxylated bile acids and insulin secretion during glucose tolerance tests in rats fed a high-fat and high-sucrose diet.
Reika Yoshitsugu, Keidai Kikuchi, Shota Hori, Hitoshi Iwaya, Masahito Hagio, Hidehisa Shimizu, Tohru Hira, Satoshi Ishizuka
Lipids in health and disease, 19, 1, 9, 9, 15 Jan. 2020, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, BACKGROUND: Previously, we found a significant relationship in a rat study between energy intake and bile acid (BA) metabolism especially 12α-hydroxylated (12αOH) BAs. The present study was designed to reveal relationships among BA metabolism, glucose tolerance, and cecal organic acids in rats fed a high-fat and high-sucrose diet (HFS) by using multivariate and multiple regression analyses in two types of glucose tolerance tests (GTTs). METHODS: Male WKAH/HkmSlc rats were fed with a control or a HFS for 13 weeks. Oral glucose tolerance test (OGTT) and intraperitoneal glucose tolerance test (IPGTT) were performed at week 9 and 11, respectively. BAs were analyzed by using ultra high-performance liquid chromatography-mass spectrometry. Organic acid concentrations in cecal contents were analyzed by using ultra high-performance liquid chromatography with post-column pH buffered electric conductivity method. RESULTS: A positive correlation of aortic 12αOH BA concentration was observed with energy intake and visceral adipose tissue weight. We found that an increase of 12αOH BAs in enterohepatic circulation, intestinal contents and feces in the HFS-fed rats compared to those in control rats regardless of no significant increase of total BA concentration in the feces in the test period. Fecal 12αOH BA concentration was positively correlated with maximal insulin level in OGTT and area under curve of insulin in IPGTT. There was a positive correlation between aortic 12αOH BAs concentration and changes in plasma glucose level in both OGTT and IPGTT. In contrast, a decrease in the concentration of organic acids was observed in the cecal contents of the HFS-fed rats. Multiple linear regression analysis in the IPGTT revealed that the concentrations of aortic 12αOH BA and cecal acetic acid were the predictors of insulin secretion. Moreover, there was a positive correlation between concentration of portal 12αOH BAs and change in insulin concentration of peripheral blood in the IPGTT. CONCLUSION: The distribution analysis of BA compositions accompanied by GTTs revealed a close relationship between 12αOH BA metabolism and insulin secretion in GTTs in rats.

Ingestion of difructose anhydride III partially suppresses the deconjugation and 7α-dehydroxylation of bile acids in rats fed with a cholic acid-supplemented diet.
Dong Geun Lee, Shota Hori, Ohji Kohmoto, Shinri Kitta, Ryo Yoshida, Yasutake Tanaka, Hidehisa Shimizu, Keisuke Takahashi, Taizo Nagura, Hirokatsu Uchino, Satoru Fukiya, Atsushi Yokota, Satoshi Ishizuka
Bioscience, biotechnology, and biochemistry, 83, 7, 1329, 1335, Jul. 2019, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, Difructose anhydride III (DFAIII) is a prebiotic involved in the reduction of secondary bile acids (BAs). We investigated whether DFAIII modulates BA metabolism, including enterohepatic circulation, in the rats fed with a diet supplemented with cholic acid (CA), one of the 12α-hydroxylated BAs. After acclimation, the rats were fed with a control diet or a diet supplemented with DFAIII. After 2 weeks, each group was further divided into two groups and was fed diet with or without CA supplementation at 0.5 g/kg diet. BA levels were analyzed in aortic and portal plasma, liver, intestinal content, and feces. As a result, DFAIII ingestion reduced the fecal deoxycholic acid level via the partial suppression of deconjugation and 7α-dehydroxylation of BAs following CA supplementation. These results suggest that DFAIII suppresses production of deoxycholic acid in conditions of high concentrations of 12α-hydroxylated BAs in enterohepatic circulation, such as obesity or excess energy intake. Abbreviation: BA: bile acid; BSH: bile salt hydrolase; CA: cholic acid; DCA: deoxycholic acid; DFAIII: difructose anhydride III; MCA: muricholic acid; MS: mass spectrometry; NCDs: non-communicable diseases; LC: liquid chromatography; SCFA: short-chain fatty acid; TCA: taurocholic acid; TCDCA: taurochenodeoxycholic acid; TDCA: taurodeoxycholic acid; TUDCA: tauroursodeoxychlic acid; TαMCA: tauro-α-muricholic acid; TβMCA: tauro-β-muricholic acid; TωMCA: tauro-ω-muricholic acid.

Alteration of Bile Acid Metabolism by a High-Fat Diet Is Associated with Plasma Transaminase Activities and Glucose Intolerance in Rats.
Yoshitsugu R, Kikuchi K, Iwaya H, Fujii N, Hori S, Lee DG, Ishizuka S
Journal of Nutritional Science and Vitaminology, 65, 1, 45, 51, 2019, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]

Marginal iron deficiency enhances liver triglyceride accumulation in rats fed a high-sucrose diet.
Hori S, Hara H, Ishizuka S
Bioscience, Biotechnology, and Biochemistry, 82, 12, 2140, 2148, Dec. 2018, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]

Application of red pigment producing edible fungi for development of a novel type of functional cheese
Kumura Haruto, Ohtsuyama Takeru, Matsusaki Yoh-hey, Taitoh Miho, Koyanagi Haruka, Kobayashi Ken, Hayakawa Toru, Wakamatsu Jun-ichi, Ishizuka Satoshi
JOURNAL OF FOOD PROCESSING AND PRESERVATION, 42, 10, Oct. 2018, [Peer-reviewed]
English, Scientific journal

Influence of AHRR Pro189Ala polymorphism on kidney functions
Kazuhiro Nakayama, Shinichi Saito, Kazuhisa Watanabe, Hiroshi Miyashita, Fuyuhiko Nishijima, Yoshie Kamo, Koji Tada, Satoshi Ishizuka, Toshimitsu Niwa, Sadahiko Iwamoto, Hidehisa Shimizu
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 81, 6, 1120, 1124, 2017, [Peer-reviewed]
English, Scientific journal

Combination of soya pulp and Bacillus coagulans lilac-01 improves intestinal bile acid metabolism without impairing the effects of prebiotics in rats fed a cholic acid-supplemented diet
Yeonmi Lee, Reika Yoshitsugu, Keidai Kikuchi, Ga-Hyun Joe, Misaki Tsuji, Takuma Nose, Hidehisa Shimizu, Hiroshi Hara, Kimiko Minamida, Kazunori Miwa, Satoshi Ishizuka
BRITISH JOURNAL OF NUTRITION, 116, 4, 603, 610, Aug. 2016, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Physiological concentrations of trans-11 18:1 vaccenic acid suppress pro-inflammatory markers under acute inflammation in isolated ICR mice splenocytes
Jae-Sung Lee, Ji-Na Lim, Tao Wang, Sang-Bum Lee, Jin-Hee Hwang, U-Suk Jung, Min-Jeong Kim, Seong-Ho Choi, Satoshi Ishizuka, Hong-Gu Lee
FOOD SCIENCE AND BIOTECHNOLOGY, 25, 1, 275, 281, Feb. 2016, [Peer-reviewed], ［Internationally co-authored］
English, Scientific journal

Megalo-type alpha-1,6-glucosaccharides induce production of tumor necrosis factor alpha in primary macrophages via toll-like receptor 4 signaling
Ga-Hyun Joe, Midori Andoh, Aki Shinoki, Weeranuch Lang, Yuya Kumagai, Juri Sadahiro, Masayuki Okuyama, Atsuo Kimura, Hidehisa Shimizu, Hiroshi Hara, Satoshi Ishizuka
BIOMEDICAL RESEARCH-TOKYO, 37, 3, 179, 186, 2016, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Activity of ERK regulates mucin 3 expression and is involved in undifferentiated Caco-2 cell death induced by 3-oxo-C-12-homoserine lactone
Hidehisa Shimizu, Nanako Baba, Takuma Nose, Ryoko Taguchi, Shinya Tanaka, Ga-Hyun Joe, Hideaki Maseda, Nobuhiko Nomura, Masahito Hagio, Ja-Young Lee, Satoru Fukiya, Atsushi Yokota, Satoshi Ishizuka, Hitoshi Miyazaki
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 79, 6, 937, 942, Jun. 2015, [Peer-reviewed]
English, Scientific journal

Diet supplementation with cholic acid promotes intestinal epithelial proliferation in rats exposed to gamma-radiation
Masahito Hagio, Hidehisa Shimizu, Ga-Hyun Joe, Manami Takatsuki, Maiko Shiwaku, Hong Xu, Ja-Young Lee, Nobuyuki Fujii, Satoru Fukiya, Hiroshi Hara, Atsushi Yokota, Satoshi Ishizuka
TOXICOLOGY LETTERS, 232, 1, 246, 252, Jan. 2015, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Deoxycholic Acid Is Involved in the Proliferation and Migration of Vascular Smooth Muscle Cells
Hidehisa Shimizu, Masahito Hagio, Hitoshi Iwaya, Ikuya Tsuneki, Ja-Young Lee, Satoru Fukiya, Atsushi Yokota, Hitoshi Miyazaki, Hiroshi Hara, Satoshi Ishizuka
JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY, 60, 6, 450, 454, Dec. 2014, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Mucin 3 is involved in intestinal epithelial cell apoptosis via N-(3-oxododecanoyl)-L-homoserine lactone-induced suppression of Akt phosphorylation
Ryoko Taguchi, Shinya Tanaka, Ga-Hyun Joe, Hideaki Maseda, Nobuhiko Nomura, Junji Ohnishi, Satoshi Ishizuka, Hidehisa Shimizu, Hitoshi Miyazaki
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY, 307, 2, C162, C168, Jul. 2014, [Peer-reviewed]
English, Scientific journal

Acyl-homoserine lactones suppresses IEC-6 cell proliferation and increase permeability of isolated rat colon
Ga-Hyun Joe, Midori Andoh, Mikako Nomura, Hitoshi Iwaya, Jae-Sung Lee, Hidehisa Shimizu, Youhei Tsuji, Hideaki Maseda, Hitoshi Miyazaki, Hiroshi Hara, Satoshi Ishizuka
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 78, 3, 462, 465, 2014, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Contribution of Dipeptidyl Peptidase IV to the Severity of Dextran Sulfate Sodium-Induced Colitis in the Early Phase
Hitoshi Iwaya, Nobuyuki Fujii, Masahito Hagio, Hiroshi Hara, Satoshi Ishizuka
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 77, 7, 1461, 1466, Jul. 2013, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

A novel mechanism for the promotion of quercetin glycoside absorption by megalo alpha-1,6-glucosaccharide in the rat small intestine
Aki Shinoki, Weeranuch Lang, Charin Thawornkuno, Hee-Kwon Kang, Yuya Kumagai, Masayuki Okuyama, Haruhide Mori, Atsuo Kimura, Satoshi Ishizuka, Hiroshi Hara
FOOD CHEMISTRY, 136, 2, 293, 296, Jan. 2013, [Peer-reviewed]
English, Scientific journal

Zinc deficiency induces dysregulation of cytokine productions in an experimental colitis of rats
Erwin Suwendi, Hitoshi Iwaya, Jae-Sung Lee, Hiroshi Hara, Satoshi Ishizuka
BIOMEDICAL RESEARCH-TOKYO, 33, 6, 329, 336, Dec. 2012, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

The Delay in the Development of Experimental Colitis from Isomaltosyloligosaccharides in Rats Is Dependent on the Degree of Polymerization
Hitoshi Iwaya, Jae-Sung Lee, Shinya Yamagishi, Aki Shinoki, Weeranuch Lang, Charin Thawornkuno, Hee-Kwon Kang, Yuya Kumagai, Shiho Suzuki, Shinichi Kitamura, Hiroshi Hara, Masayuki Okuyama, Haruhide Mori, Atsuo Kimura, Satoshi Ishizuka
PLOS ONE, 7, 11, e50658, Nov. 2012, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Glycochenodeoxycholic acid promotes proliferation of intestinal epithelia via reduction of cyclic AMP and increase in H2AX phosphorylation after exposure to gamma-rays
Satoshi Ishizuka, Maiko Shiwaku, Masahito Hagio, Takuya Suzuki, Tohru Hira, Hiroshi Hara
BIOMEDICAL RESEARCH-TOKYO, 33, 3, 159, 165, Jun. 2012, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Mucosal permeability is an intrinsic factor in susceptibility to dextran sulfate sodium-induced colitis in rats
Hitoshi Iwaya, Koushi Maeta, Hiroshi Hara, Satoshi Ishizuka
EXPERIMENTAL BIOLOGY AND MEDICINE, 237, 4, 451, 460, Apr. 2012, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Is bile acid a determinant of the gut microbiota on a high-fat diet?
Atsushi Yokota, Satoru Fukiya, Tadasuke Ooka, Yoshitoshi Ogura, Tetsuya Hayashi, Satoshi Ishizuka
Gut Microbes, 3, 5, 455, 459, Landes Bioscience, 2012, [Peer-reviewed], [Last author]
English, Scientific journal

Bile Acid Is a Host Factor That Regulates the Composition of the Cecal Microbiota in Rats
K. B. M. Saiful Islam, Satoru Fukiya, Masahito Hagio, Nobuyuki Fujii, Satoshi Ishizuka, Tadasuke Ooka, Yoshitoshi Ogura, Tetsuya Hayashi, Atsushi Yokota
GASTROENTEROLOGY, 141, 5, 1773, 1781, Nov. 2011, [Peer-reviewed]
English, Scientific journal

Marginal Zinc Deficiency Exacerbates Experimental Colitis Induced by Dextran Sulfate Sodium in Rats
Hiroshi Iwaya, Munenori Kashiwaya, Aki Shinoki, Jae-Sung Lee, Kumiko Hayashi, Hiroshi Hara, Satoshi Ishizuka
JOURNAL OF NUTRITION, 141, 6, 1077, 1082, Jun. 2011, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Immunomodulatory effect of mushrooms on cytotoxic activity and cytokine production of intestinal lamina propria leukocytes does not necessarily depend on beta-glucan contents
Jae-Sung Lee, Kohsuke Oka, Osamu Watanabe, Hiroshi Hara, Satoshi Ishizuka
FOOD CHEMISTRY, 126, 4, 1521, 1526, Jun. 2011, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

A partially degraded product of phytate suppresses the proliferation of HCT116 colorectal cancer cells
Satoshi Ishizuka, Ken-ichi Saitoh, Takuya Suzuki, Jae-Sung Lee, Hiroshi Hara
FOOD CHEMISTRY, 125, 4, 1219, 1225, Apr. 2011, [Peer-reviewed], [Lead author]
English, Scientific journal

Bile acid analysis in various biological samples using ultra performance liquid chromatography/electrospray ionization-mass spectrometry (UPLC/ESI-MS).
Hagio M, Matsumoto M, Ishizuka S
Methods in Molecular Biology (Clifton, N.J.), 708, 119, 129, 2011, [Peer-reviewed], [Invited], [Last author, Corresponding author]

Inulin Prolongs Survival of Intragastrically Administered Lactobacillus plantarum No. 14 in the Gut of Mice Fed A High-Fat Diet
Naoki Takemura, Masahiro Hagio, Satoshi Ishizuka, Hiroyuki Ito, Tatsuya Morita, Kei Sonoyama
JOURNAL OF NUTRITION, 140, 11, 1963, 1969, Nov. 2010, [Peer-reviewed]
English, Scientific journal

Voluntary wheel running exercise and dietary lactose concomitantly reduce proportion of secondary bile acids in rat feces
Masahito Hagio, Megumi Matsumoto, Takaji Yajima, Hiroshi Hara, Satoshi Ishizuka
JOURNAL OF APPLIED PHYSIOLOGY, 109, 3, 663, 668, Sep. 2010, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

A novel mechanism underlying phytate-mediated biological action-phytate hydrolysates induce intracellular calcium signaling by a G alpha q protein-coupled receptor and phospholipase C-dependent mechanism in colorectal cancer cells
Takuya Suzuki, Teruhiro Nishioka, Satoshi Ishizuka, Hiroshi Hara
MOLECULAR NUTRITION & FOOD RESEARCH, 54, 7, 947, 955, Jul. 2010, [Peer-reviewed]
English, Scientific journal

Improved Isolation Methods for Mucosal Leukocytes from Small and Large Intestines in Rats
Jae-Sung Lee, Kohsuke Oka, Mie Obara, Megumi Nishimukai, Yung-Choon Yoo, Kaori Yamada, Takamitsu Tsukahara, Keizo Nakayama, Hiroshi Hara, Satoshi Ishizuka
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 73, 8, 1732, 1740, Aug. 2009, [Peer-reviewed], [Last author, Corresponding author], ［Internationally co-authored］
English, Scientific journal

Administration of anti-glucagon-like peptide-2 serum suppresses epithelial cell proliferation of the distal small intestine in weanling rats
Satoshi Ishizuka, Ayako Inafune, Tohru Hira, Hirohisa Izumi, Kazuhiro Ozawa, Mitsunori Takase, Hiroshi Hara
BIOMEDICAL RESEARCH-TOKYO, 30, 4, 259, 261, Aug. 2009, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

alpha-Lactalbumin Hydrolysate Stimulates Glucagon-Like Peptide-2 Secretion and Small Intestinal Growth in Suckling Rats
Hirohisa Izumi, Satoshi Ishizuka, Ayako Inafune, Tohru Hira, Kazuhiro Ozawa, Takashi Shimizu, Mitsunori Takase, Hiroshi Hara
JOURNAL OF NUTRITION, 139, 7, 1322, 1327, Jul. 2009, [Peer-reviewed]
English, Scientific journal

Synbiotic promotion of epithelial proliferation by orally ingested encapsulated Bifidobacterium breve and raffinose in the small intestine of rats
Satoshi Ishizuka, Ami Iwama, Achmad Dinoto, Akarat Suksomcheep, Kohshi Maeta, Takanori Kasai, Hiroshi Hara, Atsushi Yokota
MOLECULAR NUTRITION & FOOD RESEARCH, 53, S62, S67, May 2009, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Depletion of CD8 alpha(+) lymphocytes attenuates CCL28 expression in villus epithelia in rats
Jae-Sung Lee, Saki Kamada, Yuri Takami, Kohsuke Oka, Yuichi Ochiai, Hitoshi Iwaya, Hiroshi Hara, Satoshi Ishizuka
IMMUNOLOGY LETTERS, 124, 1, 50, 54, May 2009, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Improved analysis of bile acids in tissues and intestinal contents of rats using LC/ESI-MS
Masahito Hagio, Megumi Matsumoto, Michihiro Fukushima, Hiroshi Hara, Satoshi Ishizuka
JOURNAL OF LIPID RESEARCH, 50, 1, 173, 180, Jan. 2009, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Attenuation of interferon-gamma mRNA expression in activated Jurkat T cells by exogenous zinc via down-regulation of the calcium-independent PKC-AP-1 signaling pathway
Kumiko Hayashi, Satoshi Ishizuka, Chieko Yokoyama, Toshihisa Hatae
LIFE SCIENCES, 83, 1-2, 6, 11, Jul. 2008, [Peer-reviewed]
English, Scientific journal

Modulation of rat cecal microbiota by administration of raffinose and encapsulated Bifidobacterium breve
A Dinoto, A Suksomcheep, S Ishizuka, H Kimura, S Hanada, Y Kamagata, K Asano, F Tomita, A Yokota
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 72, 1, 784, 792, Jan. 2006, [Peer-reviewed]
English, Scientific journal

Promotive effects of non-digestible disaccharides on rat mineral absorption depend on the type of saccharide
P Asvarujanon, S Ishizuka, H Hara
NUTRITION, 21, 10, 1025, 1035, Oct. 2005, [Peer-reviewed]
English, Scientific journal

Strain and age-related changes in the localization of intestinal CD161(+) natural killer cells and CD8(+) Intraepithelial lymphocytes along the longitudinal crypt axis in inbred rats
H Xu, S Imanishi, K Yamada, H Hara, S Ishizuka
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 69, 3, 567, 574, Mar. 2005, [Peer-reviewed], [Last author, Corresponding author]
English, Scientific journal

Fermentable dietary fiber potentiates the localization of immune cells in the rat large intestinal crypts
S Ishizuka, S Tanaka, H Xu, H Hara
EXPERIMENTAL BIOLOGY AND MEDICINE, 229, 9, 876, 884, Oct. 2004, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Inhibitory effects of psyllium on rat mineral absorption were abolished by reduction of viscosity with partial hydrolysis
P Asvarujanon, S Ishizuka, H Hara
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 68, 8, 1737, 1742, Aug. 2004, [Peer-reviewed]
English, Scientific journal

Reducing effect of ingesting tannic acid on the absorption of iron, but not of zinc, copper and manganese by rats
K Afsana, K Shiga, S Ishizuka, H Hara
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 68, 3, 584, 592, Mar. 2004, [Peer-reviewed]
English, Scientific journal

Intrarectal administration of deoxycholate selectively reduces small aberrant crypt foci in the rat colorectum
S Ishizuka, H Sakai, Y Yoshioka
NUTRITION RESEARCH, 23, 12, 1703, 1708, Dec. 2003, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Poly(ADP-ribose) polymerase-1 is a survival factor for radiation-exposed intestinal epithelial stem cells in vivo
S Ishizuka, K Martin, C Booth, CS Potten, G de Murcia, A Burkle, TBL Kirkwood
NUCLEIC ACIDS RESEARCH, 31, 21, 6198, 6205, Nov. 2003, [Peer-reviewed], [Lead author], ［Internationally co-authored］
English, Scientific journal

Ingestion of an indigestible saccharide, difructose anhydride III, partially prevents the tannic acid-induced suppression of iron absorption in rats
K Afsana, K Shiga, S Ishizuka, H Hara
JOURNAL OF NUTRITION, 133, 11, 3553, 3560, Nov. 2003, [Peer-reviewed]
English, Scientific journal

Relationship between formation of aberrant crypts and acute responses of colonic epithelial cells to genotoxic treatment among inbred rat strains
S Ishizuka, A Takeuchi, M Hagio, M Mohara, H Sakai, K Yamada
CANCER LETTERS, 196, 2, 135, 141, Jul. 2003, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Reduction of aberrant crypt foci by ingestion of polydextrose in the rat colorectum
S Ishizuka, T Nagai, H Hara
NUTRITION RESEARCH, 23, 1, 117, 122, Jan. 2003, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Liberation of free fatty acids from milk fat by lactic acid bacteria
A Kimura, H Kumura, S Ishizuka, K Mikawa, K Shimazaki, Z Saito
MILCHWISSENSCHAFT-MILK SCIENCE INTERNATIONAL, 58, 11-12, 609, 611, 2003, [Peer-reviewed]
English, Scientific journal

Modulation of CD8(+) intraepithelial lymphocyte distribution by dietary fiber in the rat large intestine
S Ishizuka, S Tanaka
EXPERIMENTAL BIOLOGY AND MEDICINE, 227, 11, 1017, 1021, Dec. 2002, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Dietary sugar beet fiber ameliorates diarrhea as an acute gamma-radiation injury in rats
S Ishizuka, S Ito, T Kasai, H Hara
RADIATION RESEARCH, 154, 3, 261, 267, Sep. 2000, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Dietary sugar beet fiber prevents the increase in aberrant crypt foci induced by gamma-irradiation in the colorectum of rats treated with an immunosuppressant
T Nagai, S Ishizuka, H Hara, Y Aoyama
JOURNAL OF NUTRITION, 130, 7, 1682, 1687, Jul. 2000, [Peer-reviewed], [Corresponding author]
English, Scientific journal

Ingestion of sugar beet fiber enhances irradiation-induced aberrant crypt foci in the rat colon under an apoptosis-suppressed condition
S Ishizuka, S Ito, M Onuma, T Kasai, K Aoyama, H Hara
CARCINOGENESIS, 20, 6, 1005, 1009, Jun. 1999, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Dietary wheat bran modulates proliferating cell nuclear antigen-labeling index of the rat colorectum after treatment with 1,2-dimethylhydrazine
S Ishizuka, T Kasai
JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY, 43, 6, 665, 671, Dec. 1997, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Suppression of the number of aberrant crypt foci of rat colorectum by ingestion of sugar beet fiber regardless of administration of anti-asialo GM(1)
S Ishizuka, T Kasai
CANCER LETTERS, 121, 1, 39, 43, Dec. 1997, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Changes in the number and apoptosis of epithelial cells in the colorectum of wheat bran-fed rats soon after administering 1,2-dimethylhydrazine
S Ishizuka, K Sonoyama, T Kasai
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 61, 8, 1337, 1341, Aug. 1997, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

Inhibitory effect of dietary wheat bran on formation of aberrant crypt foci in rat colon induced by a single injection of 1,2-dimethylhydrazine
S Ishizuka, T Kasai
BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 60, 12, 2084, 2085, Dec. 1996, [Lead author, Corresponding author]
English, Scientific journal

Administration of anti-asialo GM(1) serum increases aberrant crypt foci induced by 1,2-dimethylhydrazine in the large bowel of rats
S Ishizuka, T Nagai, T Kasai
JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY, 42, 6, 603, 608, Dec. 1996, [Peer-reviewed], [Lead author, Corresponding author]
English, Scientific journal

FOOD-DEPRIVATION INCREASES APOPTOTIC CELL COUNTS INDUCED BY 1,2-DIMETHYLHYDRAZINE IN RAT DESCENDING COLONIC AND RECTAL CRYPTS
S ISHIZUKA, K SONOYAMA, R NIKI
JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY, 40, 4, 363, 369, Aug. 1994, [Peer-reviewed], [Lead author, Corresponding author]
English

Influence of homogenization of milk on fatty acid contents in cheese
Ishizuka Satoshi, Saito Zenichi
Memoirs of the Faculty of Agriculture, Hokkaido University, 19, 2, 289, 294, Hokkaido University, 1994, [Peer-reviewed], [Lead author]

Basic Protocols in Foods and Nutrition　　　　　　　　　　　　　　　
Shota Hori, Hongxia Liu, Riho Yamada, Shun Ichitsubo, Ayana Sakaguchi, Fumika Yokoyama, Satoshi Ishizuka, Extraction of Bile Acids from Biological Samples and Quantification Using Ultra-High-Performance Liquid Chromatography-Orbitrap Mass Spectrometry
Humana Press, Springer, 2022, [Contributor]

Metabolic Profiling, Methods in Molecular Biology　　　　　　　　　　　　　　　
Hagio M, Matsumoto M, Ishizuka S, Bile acid analysis in various biological samples using ultra performance liquid chromatography/electrospray mass spectrometry (UPLC/ESI-MS)
Humana Press, Springer, 2011, [Contributor]

消化管の栄養・生理と腸内細菌　　　　　　　　　　　　　　　
石塚 敏, 腸管免疫系細胞の存在位置とその粘膜恒常性維持における役割
Hindgut Club Japan, 2010, [Contributor]

摂取エネルギーの増加に伴う胆汁酸代謝変動と未病症状 −腸内細菌叢との関係を考える−　　　　　　　　　　　　　　　
石塚 敏
日本食物繊維学会第30回学術集会, 18 Oct. 2025, Japanese, Nominated symposium
[Invited], [Domestic Conference]

肝疾患発症における胆汁酸代謝の役割：マウスを用いた食餌負荷実験から得られた知見　　　　　　　　　　　　　　　
石塚 敏
第55回 日本栄養・食糧学会北海道支部大会, 22 Sep. 2025, Japanese, Invited oral presentation
[Invited]

隠れ脂肪肝と胆汁酸代謝　　　　　　　　　　　　　　　
細胞工学研究会, 11 Jul. 2025
[Invited]

Metabolic alteration induced by 12-hydroxylated bile acids and disease onsets　　　　　　　　　　　　　　　
Satoshi Ishizuka
第78回 日本栄養・食糧学会大会, 25 May 2024, Japanese, Nominated symposium
[Invited], [Domestic Conference]

12水酸化一次胆汁酸による回腸透過性の亢進作用　　　　　　　　　　　　　　　
石塚 敏
第77回 日本栄養・食糧学会大会, 14 May 2023
[Domestic Conference]

12α水酸化一次胆汁酸による消化管バリア機能の脆弱化　　　　　　　　　　　　　　　
石塚 敏
15 Jul. 2022, 細胞工学研究会, Japanese, Invited oral presentation
Japan, [Invited], [Domestic Conference]

胆汁酸代謝に着目した未病モデルの構築　　　　　　　　　　　　　　　
石塚 敏
第2回 ファーマラボEXPO大阪 アカデミックフォーラム, 11 Mar. 2022, Public discourse

12α-Hydroxylated bile acid as a biomarker in an early phase of noncommunicable diseases　　　　　　　　　　　　　　　
Satoshi Ishizuka
Hokkaido University-University of Melbourne Virtual Conference on Healthy Ageing, 08 Mar. 2022, English, Nominated symposium
[International presentation]

Diet-related presymptomatic disease models in experimental animals　　　　　　　　　　　　　　　
石塚 敏
第3回 ファーマラボEXPO東京 アカデミックフォーラム, 09 Dec. 2021, Japanese, Public discourse

ラットにおける12α水酸化胆汁酸による肝脂質蓄積と関連症状　　　　　　　　　　　　　　　
石塚 敏
第75回 日本栄養・食糧学会大会, 04 Jul. 2021, Japanese, Nominated symposium
03 Jul. 2021 - 04 Jul. 2021, [Invited]

高脂肪食摂取による代謝変動と12α水酸化胆汁酸の分泌増大　　　　　　　　　　　　　　　
石塚 敏
日本農芸化学会 2021年度大会, 19 Mar. 2021, Japanese, Nominated symposium
18 Mar. 2021 - 19 Mar. 2021, [Invited]

腸内環境を介する食の作用 機能性食品の作用評価事例　　　　　　　　　　　　　　　
石塚 敏
日本薬局協励会 令和元年度学術繁栄講座, 16 Oct. 2019, Japanese, Public discourse
[Invited], [Domestic Conference]

未病としての軽度亜鉛欠乏　　　　　　　　　　　　　　　
石塚 敏
第８回 愛媛大学食品健康科学研究セミナー, 12 Sep. 2019, Japanese, Nominated symposium
[Invited], [Domestic Conference]

肝脂質蓄積におけるオリゴ糖の関与　　　　　　　　　　　　　　　
石塚 敏
食成分・栄養研究会セミナー・第367回 細胞工学研究会講演会, 29 Jun. 2019, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

実験動物で未病状態を再現する　　　　　　　　　　　　　　　
石塚 敏
食成分・栄養研究会セミナー, 04 Oct. 2018, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

糖代謝と胆汁酸　　　　　　　　　　　　　　　
石塚 敏
第7回 愛媛大学食品健康科学研究セミナー, 15 Sep. 2018, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸とミトコンドリア　　　　　　　　　　　　　　　
石塚 敏
7 Seas Project Research Meeting, 25 Aug. 2018, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

糖代謝変動における胆汁酸の寄与　　　　　　　　　　　　　　　
石塚 敏
第８回 オルソオルガノジェネシス検討会, 06 Jul. 2018, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

高脂肪食による胆汁酸代謝変動と耐糖能異常　　　　　　　　　　　　　　　
石塚 敏
第361回 細胞工学研究会講演会, 23 Jun. 2018, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸代謝から未病に迫る　　　　　　　　　　　　　　　
石塚 敏
第358回 細胞工学研究会講演会, 16 Dec. 2017, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

生体試料からの胆汁酸抽出・分析とその応用例　　　　　　　　　　　　　　　
石塚 敏
7 Seas Projectプレミーティング, 24 Feb. 2017, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸の代謝解析と関連病態　　　　　　　　　　　　　　　
石塚 敏
7 Seas Projectプレキックオフミーティング, 13 Oct. 2016, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸代謝に着目した新規病態モデルの確立　　　　　　　　　　　　　　　
石塚 敏
第5回 愛媛大学食品健康科学研究セミナー, 30 Sep. 2016, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸代謝と生活習慣病　　　　　　　　　　　　　　　
石塚 敏
分子細胞生物学セミナー, 12 Dec. 2015, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

胆汁酸代謝と消化管関連病態　　　　　　　　　　　　　　　
石塚 敏
第3回愛媛大学食品健康科学研究セミナー, 11 Sep. 2015, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

Metabolism of bile salts and intestinal microbiota　　　　　　　　　　　　　　　
ISHIZUKA Satoshi
Japanese Society of Gastroenterology – Asian-Pacific Association of Gastroenterology joint Conference, The 5th Asian Pacific Topic Conference., 22 Oct. 2014, English, Invited oral presentation
[Invited], [International presentation]

胆汁酸分子種の多様性と代謝性疾患における役割　　　　　　　　　　　　　　　
石塚 敏
第68回日本栄養・食糧学会大会, 01 Jun. 2014, Japanese, Invited oral presentation
[Invited], [Domestic Conference]

Pathological aspects of bile acids: its metabolism and possible roles in metabolic syndrome.　　　　　　　　　　　　　　　
ISHIZUKA Satoshi
16th Seoul National University Hokkaido University joint symposium., 13 Dec. 2013, English, Invited oral presentation
[Invited], [International presentation]

Zinc as a key factor in experimental colitis and cytokine productions in isolated mesenteric leukocytes in rats.　　　　　　　　　　　　　　　
International Society for Nutraceuticals and Functional Foods, Nov. 2011, English, Public symposium
[Invited], [International presentation]

Dietary sugar beet fiber promotes an accumulation of CD8+ intraepithelial lymphocytes in small intestine in WKAH rats.　　　　　　　　　　　　　　　
9th Vahouny dietary fiber symposium, Jun. 2010, English, Public symposium
[International presentation]

胆汁酸の動態と消化管上皮に及ぼす作用　　　　　　　　　　　　　　　
第62回日本栄養・食糧学会大会関連学術集会 Hindgut Club Japanサテライトミーティング, May 2008, Japanese, Nominated symposium
[Invited], [Domestic Conference]

ラット腸粘膜免疫系細胞の食物繊維による局在調節と免疫監視能　　　　　　　　　　　　　　　
第4回日本食品免疫学会, May 2008, Japanese, Nominated symposium
[Invited], [Domestic Conference]

コール酸摂取による腸上皮細胞生存及び増殖の亢進　　　　　　　　　　　　　　　
第13回Hindgut Club Japanミーティング, Dec. 2007, Japanese, Nominated symposium
[Invited], [Domestic Conference]

胆汁酸による腸上皮の生存促進作用　　　　　　　　　　　　　　　
第61回日本栄養・食糧学会大会関連学術集会 Hindgut Club Japanサテライトミーティング, May 2007, Japanese, Nominated symposium
[Invited], [Domestic Conference]

Dietary fiber: a new modulator for distribution of immune cells around intestinal crypt.　　　　　　　　　　　　　　　
8th Vahouny Symposium, Sep. 2004, English, Nominated symposium
[Invited], [International presentation]

栄養学的観点から眺めた粘膜免疫に関する一つのアプローチ　　　　　　　　　　　　　　　
第57回 日本栄養・食糧学会大会 Hindgut Club Japanサテライトミーティング, May 2003, Japanese, Nominated symposium
[Invited], [Domestic Conference]

消化管上皮の恒常性維持に関する基礎的研究　　　　　　　　　　　　　　　
第57回 日本栄養・食糧学会大会, May 2003, Japanese, Public symposium
[Invited], [Domestic Conference]

消化管上皮の増殖と恒常性維持　　　　　　　　　　　　　　　
第８回Hindgut Club Japanミーティング, Dec. 2002, Japanese, Nominated symposium
[Invited], [Domestic Conference]

Nutritional Biochemistry　　　　　　　　　　　　　　　
Faculty of Agriculture, Hokkaido University
2019 - Present

食品栄養化学概論　　　　　　　　　　　　　　　
北海道大学農学部
2019 - Present

食品科学特論演習　　　　　　　　　　　　　　　
北海道大学大学院農学院
2019 - Present

食品科学特論　　　　　　　　　　　　　　　
北海道大学大学院農学院
2019 - Present

一般教育演習 食べ物の安全と安心　　　　　　　　　　　　　　　
北海道大学
2008 - Present

生物機能化学実験IV　　　　　　　　　　　　　　　
北海道大学農学部
1995 - Present

生物学I　　　　　　　　　　　　　　　
2023 - 2025

食品栄養学演習　　　　　　　　　　　　　　　
北海道大学大学院農学院
2010 - 2018

食品栄養学特論　　　　　　　　　　　　　　　
北海道大学大学院農学院
2010 - 2018

食資源科学総論　　　　　　　　　　　　　　　
北海道大学大学院農学院
2010 - 2018

食資源科学演習　　　　　　　　　　　　　　　
北海道大学大学院農学院
2010 - 2018

2022 - Present
日本食品分析学会　　　　　　　　　　　　　　　

2012 - Present
American Society for Nutrition　　　　　　　　　　　　　　　

2005 - Present
The Molecular Biology Society of Japan　　　　　　　　　　　　　　　

1995 - Present
Japan Society of Nutrition and Food Science　　　　　　　　　　　　　　　

1992 - Present
Japan Society for Bioscience, Biotechnology, and Agrochemistry　　　　　　　　　　　　　　　

Developing and Implementing Health Promotion Strategies to Extend Healthy Lifespan: A Japan-Australia Collaboration
Grants-in-Aid for Scientific Research
09 Sep. 2024 - 31 Mar. 2029
澤村 大輔, 石塚 敏, 矢野 理香, 長谷川 直哉, 稲垣 侑士
Japan Society for the Promotion of Science, Fund for the Promotion of Joint International Research (International Collaborative Research), Hokkaido University, 24KK0038

12α水酸化胆汁酸による肝脂質蓄積機構ー脂質輸送と鉄代謝の寄与ー
科学研究費助成事業
01 Apr. 2023 - 31 Mar. 2027
石塚 敏, 田中 誠也
非アルコール性脂肪肝疾患の頻度は年々増加し、その発症には脂質蓄積に炎症・繊維化が積み重なると考えられている。汎用される高脂肪食摂取でも炎症・線維化が生じており、上記2つの段階を明確には区別できない。我々は、摂取エネルギー過多で起こる12α水酸化胆汁酸(12αOH)代謝を模倣することで炎症・線維化を伴わない独自の脂肪肝モデルを確立した。これは摂取エネルギー過多で起こる脂肪肝発症初期に生ずる多様な特徴を示す。本研究では、主にこの新規脂肪肝モデルを用いて肝脂質蓄積の誘導機構に関わる経路解明、特に腸肝循環における12αOHの増加が、安定同位体で標識した脂肪酸の輸送等の脂質代謝に及ぼす影響を検証するとともに、肝脂質蓄積に関わる因子の役割と鉄代謝の関与を明らかにする。
Poly(ADP-ribose)polymerase-1（PARP1）はNAD+を基質として核内タンパク質のポリADPリボシル化を介して転写調節に関与し、腸肝循環関連では消化管上皮の生存因子である。肝臓では、このPARP1依存的なPPARαのポリADPリボシル化が脂肪酸酸化を抑制することが脂肪肝形成に関わり得る。そこで、この経路の関与を明らかにするために、免疫沈降等を用いてPPARαに対するポリADPリボシル化活性や、CHIPアッセイを用いたCpt1発現に及ぼす作用を検証した。コール酸の食事負荷により、摂取エネルギー過多で起こる12αOH代謝を模倣したCA摂取ラットにおける肝臓のメタボローム解析の結果、NAD合成に関わる経路の活性化が見られ、Pparaとその下流で脂肪酸酸化に関わるCpt1の発現低下を確認した。これらからCA負荷ラットの肝臓ではPARP1がNAD+を基質としてPPARαをポリADPリボシル化することが脂肪酸酸化の低下につながる可能性が推察された。
日本学術振興会, 基盤研究(B), 北海道大学, 23K26846

12α水酸化胆汁酸による肝脂質蓄積機構ー脂質輸送と鉄代謝の寄与ー
科学研究費助成事業
Apr. 2023 - Mar. 2027
石塚 敏
日本学術振興会, 基盤研究(B), 北海道大学, 23H02153

腸内細菌代謝産物に焦点を当てた高食肉摂取による健康増進と病態発症の分岐点の解明
科学研究費助成事業
01 Apr. 2021 - 31 Mar. 2025
清水 英寿, 石塚 敏, 橋口 亜由未, 吹谷 智, 吉清 恵介, 田中 愛健
培養肝がん細胞を用いた解析では、スカトールはAhRだけでなくPXRにも作用して、その代表的な標的遺伝子の1つであるCYP3A4の発現増加を導いた。このためスカトールは、培養肝がん細胞に対してPXRを介した作用も発揮することが示された。
培養大腸がん細胞に対するスカトールの作用について、以前にCaco-2細胞を用いて得られた結果では、AhRの活性化を介して細胞の機能不全に導くことを報告した。今回、異なる培養大腸がん細胞であるHCT-116細胞を用いて解析を行ったところ、AhRの活性化を介して細胞増殖を誘導した。同様に、インドール酢酸やスカトールと異なるインドール系化合物の一種であるインドキシル硫酸は、AhRの活性化を介してHCT-116細胞の増殖を引き起こした。加えてAktの活性化もインドキシル硫酸によるHCT-116細胞の増殖に関与していた。以上から、同じ培養大腸がん細胞であっても、種類が異なることで、AhRの作用に違いが生じることが示された。
Caco-2細胞を用いて、インドール酢酸とスカトールのクロストークについても解析を行った。インドール酢酸とスカトールは共にCYP1A1のタンパク量を増加させるものの、スカトールによるp38の活性化は、スカトール自身およびインドール酢酸によるCYP1A1のタンパク増加を抑制した。またインドール酢酸は、スカトールによるp38の活性化を一部抑制し、その結果としてスカトールが引き起こす効果を減弱させることが示唆された。よって、インドール酢酸からスカトールへの代謝過程において、インドール酢酸とスカトールの比が、大腸上皮細胞の恒常性に影響を及ぼす可能性が示された。
日本学術振興会, 基盤研究(B), 島根大学, 23K21620

腸内細菌代謝産物に焦点を当てた高食肉摂取による健康増進と病態発症の分岐点の解明
科学研究費助成事業
01 Apr. 2021 - 31 Mar. 2025
清水 英寿, 石塚 敏, 吹谷 智, 田中 愛健, 吉清 恵介, 橋口 亜由未
本研究では、「腸内細菌代謝産物に焦点を当てた高食肉摂取による健康増進と病態発症の分岐点の解明」に向け、腸内で産生されるインドール系化合物の一種、インドール酢酸とその代謝産物であるスカトールを中心に、肝臓および腸管への影響について解析を行っている。
培養肝がん細胞を用いた解析では、スカトールは、その受容体として報告されているAryl hydrocarbon receptor （AhR）の活性化を介するだけでなく、ある核内受容体型転写因子の活性化も介して細胞増殖を導くことが明らかとなった。また我々は、スカトールによって発現増加する長寿遺伝子の1つであるSirt1が、培養肝がん細胞の増殖を導く結果を得た。
培養大腸がん細胞を用いた解析では、スカトールは、Nuclear factor-kappa B（NF-kappaB）の活性化を介してInterleukin-6（IL-6）の発現増加を導いた。またスカトールは、Tumor necrosis factor alpha（TNFalpha）を発現増加させる一方、インドール酢酸に関しては、その発現低下を導くことを我々は報告している。このTNFalphaの発現低下メカニズムとして、TLR4が関与していることが示唆された。さらにインドール酢酸は、AhRの活性化を介して、腸管上皮内腔膜の塩化物-炭酸水素交換体としてNa+/H+交換体とともに腸管での電気陰性NaCl吸収に関与しているsolute-linked carrier 26（SLC26A3）の発現増加を誘導することが明らかとなった。SLC26A3の発現低下は、炎症性腸疾患や大腸癌で観察されることから、インドール酢酸はこれら病態に対する予防および改善に寄与すると考えられる。
日本学術振興会, 基盤研究(B), 島根大学, 21H03356

12水酸化胆汁酸と関連代謝物および腸内細菌叢の解析を基盤とした未病指標の構築　　　　　　　　　　　　　　　
研究助成
2023
公益財団法人 秋山記念生命科学振興財団, Competitive research funding

12α水酸化一次胆汁酸による小腸粘膜バリア脆弱化機構-免疫応答への波及効果-　　　　　　　　　　　　　　　
Jul. 2021 - Jun. 2022
石塚 敏
公益財団法人 三島海雲記念財団, Principal investigator

新規脂肪肝モデルを用いたプレバイオティクスによる肝脂質蓄積抑制作用の検証　　　　　　　　　　　　　　　
学術研究助成金
Apr. 2021 - Apr. 2022
石塚 敏
公益財団法人飯島藤十郎記念食品科学振興財団, Principal investigator

オカラシンバイオティクスによる12α水酸化胆汁酸代謝制御を介する肝脂質蓄積の抑制作用　　　　　　　　　　　　　　　
研究助成
Apr. 2021 - Mar. 2022
石塚 敏
公益財団法人不二タンパク質研究振興財団, 一般研究, Principal investigator

Mechanism of chronic poisoning by exposure to low concentrations of microcystin and verification of mitigation methods in consideration of the intestinal environment
Grants-in-Aid for Scientific Research
29 Jun. 2018 - 31 Mar. 2021
SHIMIZU Hidehisa
In recent years, with the globalization of food, the possibility of ingestion of microcystin, a toxin derived from blue-green algae, through drinking water and freshwater seafood has been pointed out not only in developing countries but also in developed countries. In the present study, we examined the effects of chronic exposure to low concentrations of microcystin on organ function. The results showed that exposure to low concentrations of microcystin induced functional disorders in the liver and colon. Analysis using cultured hepatocytes and intestinal epithelial cells suggested the existence of unconventional pathways of microcystin action. Based on the results of present study, we expect to further elucidate the mechanism of action and search for biomarkers for chronic microcystin poisoning in the future.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Shimane University, 18K19854

Analysis of the disruption and recovery mechanism on gastrointestinal homeostasis by skatole produced by high animal protein intake
Grants-in-Aid for Scientific Research
01 Apr. 2018 - 31 Mar. 2021
SHIMIZU Hidehisa
In recent years, increased intake of red and processed meat in particular has been considered to be one of the factors in the development and progression of liver diseases (fatty liver, liver cancer, etc.) and intestinal diseases (inflammatory bowel diseases, colon cancer, etc.). In the present study, we focused on the tryptophan-derived skatole, an intestinal microbiota metabolite, which is produced in the intestine depending on the amount of protein ingested. While skatole leads to dysfunction of the liver and colon, its precursor, indole-3-acetic acid, was suggested to have the opposite effects. Therefore, the results of the present study indicate that skatole and its precursor indole-3-acetic acid may be involved in the cause of the conflicting effects of increased protein intake on health promotion, and development and progression of diseases that have been reported so far.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Shimane University, 18H03178

脂肪肝の発症及び悪化における12α水酸化胆汁酸の関与　　　　　　　　　　　　　　　
科学研究費補助金
2019 - 2021
石塚 敏
日本学術振興会, 基盤研究(B), Principal investigator, Competitive research funding

新規非アルコール性脂肪肝炎モデルを用いた乳製品・プロバイオティクスによる予防効果の検証　　　　　　　　　　　　　　　
ダノン学術研究助成金 一般研究助成
Apr. 2018 - Mar. 2019
石塚 敏
公益財団法人ダノン健康栄養財団, Principal investigator, Competitive research funding

Influence of intestinal fermentation products caused by excessive animal protein intake on intestinal and various organs.
Grants-in-Aid for Scientific Research
01 Apr. 2015 - 31 Mar. 2018
Shimizu Hidehisa, MIYAZAKI Hitoshi, ISHIZUKA Satoshi
In the present study, we analyzed the influence of skatole, an intestinal bacterial metabolite, on rats, cultured intestinal cells, and cultured hepatoma cells. As results, in rats, it was revealed that skatole induces disturbance of bile acid metabolism, change of gene expression in the liver and ileum, and dysbiosis. In the analysis using cultured intestinal cells, it was demonstrated that skatole leads to cell death via AhR activation. Furthermore, in cultured hepatoma cells, it was suggested that skatole promotes cell proliferation through activation of ERK. Based on the above results of the present study, it was shown that the production of skatole in the intestine induces abnormalities in gastrointestinal function, and may also be involved in the onset and progression of gastrointestinal diseases.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Shimane University, 15H03090

実験動物における「未病」モデルの確立と食品の生理作用評価への応用　　　　　　　　　　　　　　　
一般公募研究
Apr. 2017 - Mar. 2018
石塚 敏
一般財団法人 糧食研究会, Principal investigator, Competitive research funding

胆汁酸負荷により体内で増加する化合物の同定と生活習慣病発症における関与　　　　　　　　　　　　　　　
科学研究費補助金
Apr. 2016 - Mar. 2018
石塚 敏
日本学術振興会, 挑戦的萌芽研究, Principal investigator, Competitive research funding

Novel mechanism analysis of microcystin on organ dysfunction-focusing on bile acid metabolism-
Grants-in-Aid for Scientific Research
01 Apr. 2015 - 31 Mar. 2017
Shimizu Hidehisa, SUGIURA NORIO, MIYAZAKI HITOSHI, ISHIZUKA SATOSHI, FUKITANI SATORU
Eutrophication of lake and reservoir accelerates development of Microcystis which produces a toxin, called microcystin. The present study shows that in a cultured hepatocyte cell line, HepG2 cells, AMPK was time- and dose-dependently activated by microcystin-LR (MC-LR) stimulation. When AMPK was not activated in MC-LR-treated HepG2 cells, cell death was induced. However, when MC-LR activated AMPK, cell death was inhibited. In a cultured intestinal cell line, Caco-2 cells, MC-LR leaded to cell proliferation through p38 and JNK activation although ERK activation was not participate. Furthermore, the expression levels of oncogene was upregulated in MC-LR-treated Caco-2 cells. In rat analysis, food intake, body weight, and weight of liver, kidney, and adipose tissue were not difference between control and MC-LR-administrated rats. We will continue to check for serum parameter (ALT/AST, TG, and TC etc), liver TG and TC, and gut microbiota, etc.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Shimane University, 15K12352

Development of novel food materials for lifestyle disease prevention using edible fungi
Grants-in-Aid for Scientific Research
01 Apr. 2013 - 31 Mar. 2017
KUMURA HARUTO
Monascus species, known as red-mold has the ability to produce diverse functional secondary metabolites such as lovastatin, monascin and ankaflavin which are responsible for health benefits including risk reduction of arteriosclerosis. It would be applicable for development of functional foods, however, some strains of Monascus sp. produce nephrotoxin, citrinin. Therefore, strain and culture condition should be carefully selected. In addition to the selection of test strains, we focused on the materials for culture substrate, which should be solid with convenience for preparation, if necessary, capability to add nutritional supplements, applicability to wide pH range and “ready to eat” property of the culture products. Following the screening of the suitale strain and culture condition, the resulting culture products were fed to experimental animals whether it could exert predicted biological effects.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 25350120

食を介する健康維持の基盤：腸内細菌と脂肪細胞の制御　　　　　　　　　　　　　　　
地域イノベーション戦略支援プログラム さっぽろヘルスイノベーション‘Smart-H’
2012 - 2016
石塚 敏
文部科学省, Principal investigator

Elucidation of mechanisms to avoid chronic inflammation via enteroendocrine system: relationships between immune cells and adipocytes
Grants-in-Aid for Scientific Research
2012 - 2013
ISHIZUKA Satoshi, HIRA Tohru
Diet-induced obesity induces chronic inflammation. At postplandial period, various external antigens other than dietary lipids get into lymph ducts and evoke immune responses. In this study, we evaluated factors in lymph ducts by using lymph-cannulated rats especially at a postplandial period. At several hours after administration of dietary lipids, there was a significant increase of interleukin-6(IL-6) and glucagon-like peptide-1 in the lymph. Gene expression analysis in food-deprived or fed rats indicated that an accumulation of IL-6 producing cells in the intestinal mucosa accompanied by lipid absorption.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, Principal investigator, Competitive research funding, 24658114

Development of an innovative method for reducing colon-cancer-inducing secondary bile acid formation through enhancement of anaerobic respiration of the intestinal bacteria
Grants-in-Aid for Scientific Research
2011 - 2012
YOKOTA Atsushi, ISHIZUKA Satoshi
Some secondary bile acids formed in the large intestine are known as a riskfactor of colon cancer. In this study a novel method that reduces such secondary bile acids formed by thereductive metabolism of gut microbes were investigated. We tested if the enhancement of oxidativemetabolism of the responsible gut microbes by the introduction of anaerobic respiration can reduce thetarget secondary bile acids. Thus, rats were fed sodium fumarate-supplemented diet to enhanceanaerobic respiration of the gut microbes. Although the results suggested a possibility of decreasingrelative abundance of deoxycholic acid, a representative colon-cancer-inducing secondary bile acid, theobserved effects were not practically applicable, because high dose of fumarate was required (5~10% ofthe diet), which resulted in the diarrhea in rats experiments. Therefore, improved method of fumaratefeeding, e.g. encapsulation, might be necessary to achieve this goal.
Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 23658064

消化管陰窩におけるケモカイン分泌上皮の局在と食餌成分による調節機構
科学研究費補助金
2004 - 2006
石塚 敏
本研究では消化管リンパ球の局在とそれにおよぼす食餌成分の影響についてケモカインの関与を検討した。本研究を通じて明らかになったことは以下の通りである。これまでにもパイエル板を除いたラット小腸粘膜固有層からリンパ球の分離が可能であったが、その分離法を改善することにより回収率を上げる事に成功した。また、その方法を基にしてラット大腸粘膜からのリンパ球分離を可能にした。難消化性糖類は上部消化管で吸収されずに大腸へ流入することで、そこに存在する腸内菌に資化されることを考えれば、大腸粘膜におけるリンパ球分離法の確立は今後の重要な課題を解決するための基盤技術となりうる。食餌成分として甜菜繊維(SBF)を用いた場合、WKAHラット盲腸部位におけるCD8^+上皮間リンパ球(IEL)の頻度を有意に増加させたが、小腸でも同様な現象が観察された。興味深いことに、盲腸に比べ小腸での上昇率の方が極めて高いことが明らかになった。しかし、このSBF摂取による小腸でのCD8^+ IEL増加は、ラットの系統により異なることが示された。DAラットではこのような小腸における増加は全く確認されなかった。このことは遺伝的背景により食餌による消化管粘膜リンパ球局在調節機構が異なることを示している。小腸から機械的に陰窩および絨毛部位を分離し、それぞれRT-PCR解析を行ったところ、この部位間で異なる発現を示すものとしてCCL...
文部科学省, 若手研究(B), 北海道大学, Principal investigator, Competitive research funding, 16780088

大腸上皮内リンパ球機能の食餌成分による調節機構
科学研究費補助金
2001 - 2002
石塚 敏
昨年度の実験において、難消化性糖類の摂取によりCD8^+大腸上皮間リンパ球(IEL)の大腸粘膜への集積が生理的な範囲で起こることを明らかにした。今年度はそれ以外にCD4^+ IELとNKR-P1A^+大腸上皮間ナチュラルキラー細胞(IENK)の局在を免疫組織化学的に検討した。NKR-P1A^+ IENKは、近年になってラットのIEL画分よりその存在が明らかになった細胞集団で、NK活性を持ち、IFN-gammaとIL-4を分泌する特殊な細胞集団であることが報告されている。興味深いことに、CD8^+ IELは大腸陰窩中において既に分化した上皮細胞間に存在するのに対し、NKR-P1A^+ IENKは逆に増殖上皮細胞の近傍、すなわち陰窩底部に存在することが陰窩内セルポジションごとの解析により明らかになった。また、NKR-P1A^+ IENKの局在はCD8^+ IEL同様に盲腸に多く、以降遠位に向かって減少することも明らかになった。さらに陰窩内におけるNKR-P1A^+ IELの数はそのCD8^+ IELの数と強い正の相関を示した。これらの局在はこれまでの栄養学的な観点からの標準飼料の摂取では見られず、発酵性の難消化性糖類を添加することにより初めて顕在化されることが盲腸内容物のHPLC分析から示唆された。しかし、その集積は病理的なものではないことは組織化学的解析から明らかである。一方、...
文部科学省, 奨励研究(A), 北海道大学, Principal investigator, Competitive research funding, 13760090

Prevention of initiation and promotion of colon cancer by dietary fiber and design of highly functional dietary fiber.
Grants-in-Aid for Scientific Research
1998 - 2000
HARA Hiroshi, ISHIZUKA Satoshi
The aims of this study were to establish a model of colon cancer by ionizing radiation in rats and to compare the effects of dietary fiber feeding on cancer development with those in a chemically-induced colon cancer model. We first succeed to develop precancerous legion, aberrant crypt foci (ACF), in rat colonic mucosa by ionizing radiation. The properties of radiation-induced ACF were low frequency, but high multiplicity compared with the chemically induced ACF Feeding of a highly fermentable dietary fibers, sugarbeet fiber, suppressed ACF in the chemical model, but not the radiation model. In the chemical model, a low fermentable, soluble fiber prevent the development of colonic ACF just feeding fiber before, but not after a challenge of carcinogen. Also, a product of the colonic fermentation, butyric acid, prevented the development of ACF in the rat colon using the chemically-induced cancer model.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B)., GRADUATE SCHOOL OF AGRICULTURE, HOKKAIDO UNIVERSITY, 10460053

新規バイオポリマーの生物機能
科学研究費助成事業
1998 - 1999
青山 頼孝, 石塚 敏
Enterobacter cloacae ECP126が生産した新規バイオポリマーが血清脂質を低下させる能力を有するかどうか検討するため、バイオポリマーをラットの食事に5%添加した。ヒスチジンの添加によって誘導される内因性高コレステロール血症は、新規バイオポリマーの添加によって血清コレステロール、リン脂質のいずれも有意に低下させる作用を有することを見出した。一方、トリアシルグリセロールは低下の傾向を示した。基本食、ヒスチジン食摂取ラットの盲腸内の個々の有機酸量は変わらなかった。基本食にバイオポリマーの添加は盲腸中の酢酸、酪酸レベルを有意に増加させた。一方、ヒスチジン食にバイオポリマーの添加は、基本食にバイオポリマーを添加したときと比較して有機酸の全量は有意に低下した。さらに主要な成分である酢酸は低下の傾向、プロピオン酸は有意に低下したがバイオポリマーを添加しなかったヒスチジン食群と比較して、有機酸の全量、酢酸、プロピオン酸レベルは有意に増加した。これらの事実から、盲腸内のプロピオン酸量は血清コレステロールレベルを調節していると推定された。したがってEnterobacter cloacae ECP126から生成される新規バイオポリマーは粘度が著しく高く、血清コレステロールを低下させる機能を有する成分であり、将来利用されうる高分子化合物であることがあきらかになった。これらの成果は平成11年度日本栄養・食糧学会総会(平成11年5月29日)(東京)において"Nutritional effect of biopolymer produced by microorganism on serum lipids in rats"を口頭発表した。
日本学術振興会, 萌芽的研究, 北海道大学, 10876027

Molecular basis for establishing the environment in digestive tract by food components
Grants-in-Aid for Scientific Research
1998 - 1999
KAWABATA Jun, ISHIZUKA Satoshi, KURIHARA Hideyuki
As the inhibitory principles against rat intestinal maltase, two ellagitannins, eugeniin and casuarictin, were isolated from the methanolic extracts of Clove buds. Structure-activity relationship study of the isolates together with synthetic pentagalloylglucose (PGG), which showed the highest activity , revealed that the inhibitory activity depended on the number of uncoupled galloyl residues in the molecule. These tannins also inhibited maltase expressed on a human carcinoma cell line, Caco-2. On the other hand, the acetone extracts of roselle tea, dried flower buds of Hibiscus sabdariffa, possessed an inhibitory activity against porcine pancreatic α-amylase. The active compound was identified as hibiscus acid.
Inhibitory potencies of the extracts of seafood and algae against Escherichia coli β-glucuronidase were investigated by the colorimetric method in vitro. Among them, the extracts of dried bonito (katsuobushi), the brown alga Hizikia fusiformis, and the red alga Chondria crassicaulis showed the inhibitory activity. The inhibitor obtained from dried bonito was disclosed to be inosinic acid. Among nucleic acid-related compounds, adenylic acid and adenosine triphosphate also inhibited the β-glucuronidase. The inhibitor obtained from H. fusiformis was identified to be a mixture of free fatty acids. Isolation and structural elucidation of the inhibitor of C. crassicaulis is now in progress.
Direct effect of molecules on the formation of aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine using the intrarectal injection was investigated. Butyric acid or deoxycholic acid (and the derivatives) was used as the test molecule. Intrarectal injection of butyric acid showed a protective effect on the ACF formation at 20 mM. On the other hand, intrarectal injection of deoxycholic acid significantly promoted the size of ACF. These results suggest that the intrarectal injection with experimental animal is useful model to assess the effect of such molecules on the early phase of carcinogenesis.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 10460052

Role of genotoxic stress-induced apoptosis in the protective effect of dietary fiber against tumorigenesis in the large bowel
Grants-in-Aid for Scientific Research
1997 - 1998
KASAI Takanori, ISHIZUKA Satoshi, SONOYAMA Kei
The present study investigated the role of genotoxic stress-induced apoptosis in the protective effect of dietary fiber against tumorigenesis in the large bowel. Dietary beet fiber increased the apoptotic frequency in rat colonic epithelium at 6 h after a subcutaneous injection of carcinogen 1 , 2-dimethylhydrazine (DM11). The finding suggests that increased efficiency of elimination of damaged cells may be associated with the anti-tumorigenic effect of dietary beet fiber. Semi-quantitative RT-PCR demonstrated that increase in the expression of cyclin-dependent kinase inhibitor p21 and apoptosis inducer Bax genes, which are targets of tumor suppressor protein p53, preceded the apoptosis in rat colonic epithelium following DMH injection. In addition, gene expression of betaA-subunit of activin which is a member of TGF43 gene superfamily was also shown to be upregulated, To establish in vitro model for the investigation of these phenomena at cellular and molecular bases, we examined the time-course of changes in cell mortality and gene expression following different doses of UV irradiation in the untransformed cell line IEC-6 which was derived from rat small intestine. Cell survival rates were decreased by UV irradiation in time- and energy-dependent fashion. Agarose gel electrophoresis of cellular DNA demonstrated that the cell death was due to apoptosis. Semi-quantitative RT-PCR revealed the increase in mRNA levels of betaA-subunit of activin in IEC-6 cells following UV irradiation, being similar to that in rat colonic epithelium following DM14 treatment. The next step concerns whether the dietary fiber and its fermentation products short chain fatty acids modulate the cell cycle, apoptosis, and expression of related genes the colonic epithelial cells following genotoxic agents.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), HOKKAIDO UNIVERSITY, 09660123

Physiological and Biochemical Study of Gastrointestinal Functions.
Grants-in-Aid for Scientific Research
1997 - 1998
AOYAMA Yoritaka, ISHIZUKA Satoshi, SONOYAMA Kei, KAWABATA Jun, KASAI Takanori
(1) When rats were fed an orotic acid diet, liver lipid level of rats fed a diet containing casein was significantly higher than that of a diet containing egg protein or soybean protein. The addition of an orotic acid to a diet containing casein caused to decrease liver superoxide dismutase activity, to increase serum ornithine carbamoyl transferase activity, to increase the hepatic concentration of 1,2-diacylglycerol. Liver damage by administration of an orotic acid might be due to the increased concentration of 1,2-diaclglycerol and decreased activity of hepatic superoxide dismutase.
(2) 9-Oxooctadeca 10,12-dienoic acid as acetyl CoA carboxylase inhibitor from red pepper was found. Its activity was 50 fold higher as compared with the normal fatty acids.
(3) Dietary beet fiber had a role to supprees the formation of the aberrant crypt foci induced by 1,2-dimethylhydrazine. Furthermore, it was found that the formation of the aberrant crypt foci induced by nu -ray irradiation was suppressed by the injection of anti-asialo GMI, but not by the addition of beet fiber.
(4) Apoptosis and p53 level in epithelial cell of colon was induced by the administration of 1,2-dimethylhydrazine. Further observation was increased level of activin mRNA in colon. This is the first finding that activin is a factor to stop the cell cycle in apoptosis.
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 09306007

食物繊維による大腸上皮細胞の異常増殖抑制作用における免疫系の関与
科学研究費補助金
1997 - 1998
石塚 敏
大腸癌の前癌病変と考えられているaberrant crypt foci(ACF)は発癌物質の投与だけでなく、低線量のガンマ線照射によっても引き起こされることが我々の研究で明らかになった。大腸癌を誘発させるために比較的よく使われる発ガン物質は大腸管腔内側から作用するものが多い。一方、ガンマ線の場合は直接大腸上皮に作用し、かつ照射時間も数分であるため、比較的腸管腔内容物の影響を受けにくいと考えられる。我々はこのガンマ線誘発ACFが抗アシアロGM1投与により影響されるか、また大腸癌誘発剤である1,2-dimethylhydrazine(DMH)誘発ACFを強力に抑制した甜菜食物繊維(SBF)の摂取がガンマ線誘発ACFに対しても同様な効果を持つのかを検討した。その結果、DMH誘発ACFの場合と同様に抗アシアロGM1の投与はガンマ線誘発ACFの発生頻度を有意に増加させることが明らかになった。SBFの摂取自体はガンマ線誘発ACFに対して影響しないが、抗アシアロGM1投与下ではSBF摂取はACFの増加を有意に抑えた。また、免疫組織化学的研究から、抗アシアロGM1投与により大腸粘膜上皮内におけるCD8陽性細胞の数が有意に減少することが明らかになった。これは抗アシアロGM1投与は大腸上皮間リンパ球に影響を与えることを示唆している。これらの研究から粘膜上皮近傍のCD8陽性細胞数が減少した条件で、...
文部科学省, 奨励研究(A), 北海道大学, Principal investigator, Competitive research funding, 09760120

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Patent right
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