Abstract
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 triglyceride 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 triglyceride 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.
The economy of the enterohepatic circulation of bile acids in the baboon. 2. Regulation of bile acid synthesis by enterohepatic circulation of bile acids.
