Study On The Mechanism Of Ginsenoside Rg2 Promoting SIRT1 To Improve Non-alcoholic Fatty Liver

ObjectiveStudies have shown that ginsenoside Rg2,a monomer of traditional Chinese medicine,can reduce glucose and fat production in adipose tissue.However,the effect of ginsenoside Rg2 in non-alcoholic fatty liver disease(NAFLD)has not been reported.SIRT1 is defined as a NAD+-dependent deacetylase that participates in a variety of biological events,especially cell survival,lifespan and substance metabolism.More and more evidence shows that SIRT1 can interfere with the development of non-alcoholic fatty liver by regulating the metabolism of lipids and carbohydrates in hepatocytes.Therefore,the purpose of this study is to explore the effect of ginsenoside Rg2 on non-alcoholic fatty liver and whether it depends on the key molecule SIRT1 of epigenetics.MethodsFirstly,the hyperlipidemia model of primary hepatocytes induced by oleic acid(OA)and palmitic acid(PA)was used as the research object.After treatment with ginsenoside Rg2 and PBS,the expressions of adipogenic genes such as SREBP-1c,FAS,ACC and fatty acid oxidation-related genes and proteins such as PPAR-α and ACADVL were detected,and the oxidative stress and apoptosis of hepatocytes were observed.Secondly,the NAFLD model mice induced by high-fat diet were injected with ginsenoside Rg2 and normal saline intraperitoneally.The body weight,food intake and the contents of triglyceride(TG)and total cholesterol(TC)in liver and serum were measured.The changes of lipogenic genes,fatty acid oxidation-related genes and antioxidation-related genes in liver were detected.Finally,on the basis of NAFLD model mice,the liver tissues of ginsenoside Rg2 group and normal saline control group were analyzed by transcriptology,and liver SIRT1 specific gene knockout mice were used to further explore the possible mechanism of ginsenoside Rg2 improving liver lipid metabolism.Results1、Studies have shown that ginsenoside Rg2 significantly decreased the levels of TG and TC in OA&PA-induced hyperlipidemic mouse hepatocytes.At the same time,ginsenoside Rg2 effectively inhibited the expression of OA&PA-induced lipogenic genes SREBP-lc,FAS and ACC,and up-regulated the expression of fatty acid oxidation-related genes PPAR-α,ACADVL,ACADM,CPT2 and CPT1b,suggesting that ginsenoside Rg2 has the effect of anti-lipid deposition in hepatocytes.2、Ginsenoside Rg2 effectively inhibited the production of reactive oxygen species(ROS)induced by OA&PA,decreased the mitochondrial membrane potential of hepatocytes induced by OA&PA,and up-regulated the expression of antioxidation-related genes SOD2,KEAP1,HOMX1 and NFE2L2,suggesting that ginsenoside Rg2 can alleviate the redox dysfunction of hepatocytes induced by OA&PA.At the same time,ginsenoside Rg2 can inhibit hepatocyte apoptosis induced by OA&PA,indicating that ginsenoside Rg2 can effectively restore the redox disorder of primary mouse hepatocytes.3、In animal level,intraperitoneal injection of ginsenoside Rg2 significantly reduced the lipid deposition in the liver of NAFLD model mice,decreased the contents of TG and TC in liver and serum of NAFLD model mice,and significantly inhibited the expression levels of adipogenic genes and proteins such as SREBP-1c,FAS and ACC.In addition,ginsenoside Rg2 could improve the mitochondrial damage of hepatocytes in NAFLD model mice,reduce insulin resistance in NAFLD model mice,and up-regulate the expression levels of antioxidation-related genes SOD2,KEAP1,HOMX1 and NFE2L2 in hepatocytes of NAFLD model mice.It is suggested that ginsenoside Rg2 can improve the metabolic disorder of NAFLD model mice.4、The transcriptome results showed that ginsenoside Rg2(1Omg/kg)could inhibit the expression of lipogenesis and carbohydrate production related genes in the liver of NAFLD model mice,up-regulate the expression of genes involved in antioxidant pathway in the liver,and up-regulate the expression level of SIRT1 in the liver of NAFLD model mice.In addition,ginsenoside Rg2 increased the deacetylase activity of SIRT1 in primary hepatocyte hyperlipidemia model.Molecular docking analysis showed that ginsenoside Rg2 and SIRT1 might bind by hydrogen bond and van der Waals force.It is suggested that SIRT1 may play a potential role in the effect of ginsenoside Rg2 on resisting lipid deposition in liver and correcting metabolic disorder in liver.5、Hepatocytes were isolated from liver SIRT1 specific knockout mice.It was found that on the basis of SIRT1 deletion,the intervention effect of ginsenoside Rg2 on lipid deposition induced by OA&PA disappeared,and there was no change in the content of TG and TC,lipogenic genes SREBP-1c,FAS and ACC,and fat oxidation related genes PPARα,ACADVL and so on.In addition,SIRT1 deletion weakens the ability of ginsenoside Rg2 to regulate hepatocyte redox system and apoptosis.It is suggested that ginsenoside Rg2 may improve OA&PA-induced lipid deposition and redox system disorder in hepatocytes in a SIRT1-dependent manner.6、At the animal level,the effect of ginsenoside Rg2 on hepatic metabolic disorder in NAFLD model mice disappeared in liver SIRT1 specific gene knockout NAFLD model mice.In addition,the deletion of SIRT1 reduced the ability of ginsenoside Rg2 to improve the disorder of liver redox system and the damage of hepatocyte mitochondria in NAFLD model mice.The results suggest that ginsenoside Rg2 may be involved in the regulation of hepatic lipid metabolism disorder in a SIRT1-dependent manner.ConclusionGinsenoside Rg2 can effectively improve non-alcoholic fatty liver induced by high-fat diet by increasing liver antioxidant activity and inhibiting fat production,and its mechanism is related to the up-regulation of SIRT1 activity.The results provide scientific basis for ginsenoside Rg2 in the treatment of non-alcoholic fatty liver and related diseases.