Objective: To observe the effect of pure total flavonoids from Citrus (PTFC) on the hepatic fatty degeneration, inflammation, oxidative stress and SIRT1/PGC-1alpha expressions in mice with non-alcohol steatohepatitis (NASH), and discuss the action mechanism of PTFC on NASH.
Method: Mice were given high-fat diet for 16 weeks to induce the NASH model. Since the seventh week after the model establishment, the mice were intervened with 100, 50 and 25 mg x kg(-1) x d(-1) PTFC for 10 weeks. The pathologic changes in hepatic tissues were observed with HE staining. The contents of TG, CHOL in hepatic tissue, as well as the levels of AST, ALT in serum were detected by using the biochemical process. The expression of SIRT1, PGC-1alpha and MnSOD mRNA in hepatic tissues were detected with Real-time PCR assay. SIRT1, PGC-1alpha protein and 8-OHdG expressions were determined with the immunohistochemical method. The SOD level in hepatic tissues was tested by the xanthine oxidase method. The MDA content in hepatic tissues was examined by the thiobarbituric acid method.
Result: The contents of TG, CHOL, NAFLD activity scores and ALT level in serum in hepatic tissues of mice in the model induced by fat-rich diet were obviously higher than that of the normal group (P < 0.010. The SIRT1, PGC-1alpha, MnSOD mRNA and protein expression in hepatic tissues were significantly lower than that of the normal group (P < 0.01). The expression of 8-OHdG and the content of MDA in hepatic tissues were obviously higher than that of the normal group (P < 0.01). After the intervention with different doses of PTFC, the NAFLD activity scores, the content of TG and the level of AST in serum were notably lower than that of the normal group (P < 0.01, P < 0.05); whereas the SIRT1, PGC-1alpha, MnSOD mRNA and protein expression were obviously higher than that of the normal group (P < 0.01, P < 0.05), with the significant decrease in the expression of 8-OHdG and the content of MDA (P < 0.01).
Conclusion: Oxidative stress/lipid peroxidation enhancement in in NASH mice induced by high-fat diet may be related to the changes in SIRT1/PGC-1alpha signal transduction pathway. PTFC could enhance the anti-oxidant capacity in liver, relieve the damage of reactive oxygen during the fatty acid metabolic process, and prevent NASH from the occurrence and development by regulating the SIRT1/PGC-1alpha signal pathway.