Protective Effect Of Bergenin On Nonalcoholic Fatty Liver Disease And Its Mechanism

Objective: In this study,nonalcoholic fatty liver disease(NAFLD)model was established in C57 mice induced by high fat diet(HFD).In vitro lipid deposition model was established in Hep G2 cells treated with free fatty acid mixture(oleic acid/palmitic acid,2:1)to observe the protective effect of bergenin(BER)in nonalcoholic fatty liver.To further explore the role of SIRT1/NF-κB inflammatory pathway,AMPK/Nrf2 oxidative stress and lipid metabolism pathway,and to find a new method for alleviating liver dysfunction and treating nonalcoholic fatty liver disease.Methods: Eighty male C57BL/6J mice were randomly divided into normal group(n=15),BER 80 group(n=10)and modeling group(n=55).The rats in normal group and BER 80 group were fed normal diet,and the rats in modeling group were fed high fat diet(HFD).After 8 weeks,5 mice were randomly selected from the normal group and the modeling group for pathological examination and biochemical index detection to judge whether the NAFLD model was successful.After confirming the successful establishment of NAFLD model,the remaining 50 mice in the modeling group were randomly divided into HFD group,HFD+Silymarin group,HFD+BER 20 group,HFD+BER 40 group,and HFD+BER 80 group,with 10 mice in each group.Normal group was given normal diet,BER 80 group was given normal diet and gavage of 80mg/kg BER every day,HFD group was fed high-fat diet,HFD+Silymarin group was fed with high fat diet and gavaged with Silymarin(150 mg/kg),HFD+BER group(HFD+BER 20,HFD+BER 40,HFD+BER 80 group)was fed high-fat diet and given corresponding dose(20,40,80 mg/kg)BER for 6 weeks.Hematoxylin-eosin staining(HE)was used to observe the pathological changes of liver tissue.The activities and contents of ALT,AST,ALP,γ-GT,FBG,FINS,FFA,TG,TC,LDL-C,HDL-C,oxidative stress status in serum or liver tissue were determined by biochemical method.The expression levels of inflammatory cytokines IL-6,TNF-α and IL-1β in liver were determined by ELISA.Protein or m RNA expression levels of SIRT1/NF-κB and AMPK/Nrf2 pathways were detected by RT-PCR and Western blot.Hep G2 cells were divided into normal group,FFA group and FFA+BER lowmedium-high dose group(8,16,32 μM).MTT assay was used to detect the survival rate of Hep G2 cells,Oil Red O(ORO)staining was used to observe the lipid deposition of Hep G2 cells,RT-PCR and Western blot were used to detect m RNA or protein expression levels of SIRT1/NF-κB and AMPK/Nrf2 pathways.Results:(1)BER has a protective effect on non-alcoholic fatty liver induced by HFD and can significantly improve liver dysfunction in mice.(2)Biochemical and ELISA results showed that BER can effectively reduce inflammatory response and oxidative stress,regulate lipid metabolism,and play a protective role in liver tissue.(3)HE staining showed that BER could effectively improve the steatosis and necrosis of liver tissue.(4)ORO staining results showed that BER could reduce the lipid deposition status of Hep G2 cells after FFA intervention.(5)BER can regulate SIRT1/NF-κB and AMPK/Nrf2 pathways,significantly down-regulate the expressions of p-NF-κB p65,TNF-α,IL-6,IL-1β,SREBP-1 and FAS,and up-regulate the expressions of SIRT1,AMPK,Nrf2 and HO-1.Conclusion: BER can improve lipid metabolism and protect liver by inhibiting inflammatory response and oxidative stress.