Abstract:

Objective To investigate the effect of obeticholic acid on protein expression and gene expression of farnesolid X receptor (FXR), cytochrome 7A1 (CYP 7A1) in non-alcohol fatty liver disease (NAFLD) rat and hepatocyteprotective effect. Methods Fifty two SD rats of the non-alcoholic fatty liver model was established by feeding with high-fat diet. The control group, model group,the experimental group(low), the experimental group(middle), the experimental group(high) were set up. After four weeks of administration, the same part of the liver was taken out. The expression of FXR protein was detected by immunohistochemistry method , the mRNA expression of FXR was detected by RT-PCR, the protein CYP7A1 was detected by Western blotting and the mRNA expression of CYP7A1 was detected by RT-PCR. The liver function was assessed by the rat liver index of the concentrations of peripheral blood alanine aminotransferase (ALT), aspartate transaminase(AST) and alkaline phosphatase(ALP), and the observation of liver sections. Results After fed with high-fat diet for 10 weeks, the rats had typical characteristics of NAFLD and the model was established successfully. The expression of FXR protein and FXR mRNA in the model group were significantly lower than that in the control group (P<0.05). There was no significant difference in the expression of FXR protein and FXR mRNA between the experimental group(low) and the experimental group(middle) (P> 0.05). The expression of FXR protein and FXR mRNA in the experimental group(high) was significantly higher than that in model group (P<0.05). The optical density values of model group, the experimental group(low), and the experimental group(middle) were significantly lower than those of control group (P<0.05). The optical density values of the experimental group(high) was significantly higher, and there was no significant difference compared with those of the control group (P>0.05). The CYP7A1 protein and CYP7A1 mRNA expression levels in the model group were significantly higher than those in the control group (P<0.05). Compared with those in the model group, the expression levels of CYP7A1 protein and CYP7A1 mRNA in the experimental group(low) and the experimental group(middle) had no significant difference (P>0.05). The levels of CYP 7A1 protein and CYP 7A1 mRNA in the experimental group(high) were significantly lower than those in the model group (P<0.05). Compared with the control group, the liver index (%) of the model group increased significantly (P<0.05), while the liver index (%) of the experimental group(low) and the experimental group(middle) had no significant difference compared with the model group (P> 0.05). The liver index (%) of the experimental group(high) was significantly lower than that of the model group (P<0.05). Compared with the control group, the concentrations of ALT, AST and ALP in the model group were significantly increased (P<0.05). The levels of ALT, AST and ALP in the experimental group were significantly lower than those in model group (P<0.05), and the concentrations of ALT, AST and ALP gradually decreased with the increase of acyclobacic acid dosage. The liver tissue sections were observed. The result showed that obeticholic acid improved the histopathology of rats in a dose-dependent manner. Conclusion High doses of acyclobacic acid can significantly upregulate the expression of FXR protein and its gene, inhibit the expression of CYP 7A1 protein and its gene, and significantly improve the liver function and pathological status of rats.

Key words: Obeticholic acid, Non-alcoholic fatty liver, Farnesoid X receptor, Cytochrome 7A1 protein, Western blotting, Rat