Research Of The Efficacy And Mechanism Of Schisandrin B (SchB) In Nonalcoholic Fatty Liver Disease (NAFLD)

Objective:To detect the liver lipids, the transaminase, liver coefficient, protein expression of endoplasmic reticulum stress signaling pathway and gene expression of fatty acid synthesis-related to investigate the effects and mechanism of Schisandrin B(Sch B) on nonalcoholic fatty liver disease(NAFLD). This study may provide new ideas and methods for the treatment of NAFLD.Method: 1. ICR mice were randomly divided into the following six groups and received the corresponding treatment for 7 days:(A) mice fed with normal diet;(B) mice fed with high-fat diet;(C)-(E) mice fed with high-fat diet supplemented with 10, 20,40 mg/kg Sch B,respectively;(F) mice fed with high-fat diet supplemented with 100mg/kg fenofibrate. The mice were sacrificed and part of liver tissue samples were collected for the analysis of total triglyceride(TG), total cholesterol(TC), alanine aminotransferase(ALT), the aspartate aminotransferase(AST) and the hepatic index.The other part of liver tissue samples was fixed with methanol for pathological section. Experimental NAFLD cell model was induced by incubating a normal human hepatocytes-derived cell line L-02 with 1 m M free fatty acids(FFAs) mixture(oleate and palmitate, 2:1) for 24 hours. This model then was treated with different concentrations schisandrin(Sch B), the cellular total lipid accumulation was determined by flow cytometry(FCM). Intracellular triglyceride(TG)contents were measured using an enzymatic kit.2. The total RNA and protein were extracted from cell samples and liver samples. Proteins BIP、SREBP-1、PERK、P-PERK、P-e IF2α were detected with Western Blotting. The fatty acid synthesis-related genes, fatty acid synthesis of acetyl Co A carboxylas(ACC)、fatty acidsynthase(FAS) 、 glycerin- 3- phosphate acyltransferase(GPAT)and stearoyl-Co A desaturase(SCD) were detected with RT-PCR.Result: Compared with mice fed with high-fat diet, mice fed with low, medium, high dose of Sch B reduced TG contents in a dose-dependent manner(P < 0.05). The medium, high dose of Sch B decreased the concentrations of CHO, AST, ALT obviously. The analysis of pathology showed that the liver tissues of Sch B treatment groups were lighter injured compared with that of NAFLD model group. The analysis of hepatic index showed lower toxicity of Sch B compared with the positive drug. The protein, expressions of the endoplasmic reticulum stress signaling pathways BIP、SREBP-1、P-PERK、P-e IF2α were up-regulated in the NAFLD model and down-regulated after Sch B treatment. The RT-PCR revealed that treatment with 1 m M FFAs mixture up-regulated the expression of ACC, FAS,GPAT, which the effect could be reversed after Sch B treatment. The NAFLD cell model was successfully established in L02 cells, Sch B treatment decreased the intracellular lipid accumulation and TG contents. And the changes of proteins and genes after Sch B treatment were similar to the results of in-vivo experiment.Conclusion: All results suggested that the SchB decreasedliver lipid accumulation, TG content and transaminase in vivo and in vitro. The Sch B can reduce the proteins expression of endoplasmic reticulum stress signaling pathways and fatty acid synthesis-related genes expression of ACC, FAS,GPAT, It also increased the expression of SCD which was the target gene of leptin. In short, the Sch B can be applied in NAFLD treatment by reducing hepatic lipid accumulation.