The effects and molecular mechanisms of simvastatin on liver fibrosis in rats with non-alcoholic fatty liver disease / 中华消化杂志

ABSTRACT

ObjectiveTo investigate the effects and molecular mechanism of simvastatin in liver fibrosis model of non-alcoholic fatty liver disease (NAFLD) in vivo and hepatic stellate cell in vitro.MethodsFirstly,the rat liver fibrosis model of NAFLD was established by high-fat diet administration and intervened with simvastatin.The expression of endothelial nitric oxide synthase (eNOS),inducible nitric oxide synthase (iNOS) and Collagen Ⅰ at mRNA and protein level were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.Secondly,quiescent phenotype of LX-2 cell line was induced by promoting adipocyte differentiation medium in vitro,and then the quiescent phenotype of LX-2 cell were treated with transforming growth factor β1(TGF-β1),Nitroso-L-arginine methyl ester (L-NAME) which was NOS inhibitor,simvastatin,TGFβ1 with simvastatin,and L-NAME with simvastatin separately.The changes of eNOS,iNOS,αsmooth muscle actin (α-SMA) and Collagen Ⅰexpressions at mRNA and protein level were determined by RT-PCR and Western blot.ResultsAs modeling time extended,the expressions of eNOS in rat's liver tissue of model group at mRNA and protein level decreased gradually,however the expression of iNOS and Collagen Ⅰ at mRNA and protein level increased gradually,compared with normal control group and the differences were statistically significant (P ＜0.05 and 0.01).By 24weeks,the expressions of eNOS in rat's liver tissue of simvastatin group at mRNA and protein level were increased,the expression of iNOS at mRNA and protein level were decreased and the expression of Collagen Ⅰ at mRNA and protein level were decreased (all P ＜0.05).The expression of eNOS in rat's liver tissue of model group negatively correlated with the expression of Collagen Ⅰ at mRNA and protein level (all P ＜0.01).The expression of iNOS positively correlated with that of Collagen Ⅰ at mRNA and protein level (all P ＜0.01).In LX-2 cell culture,L-NAME inhibited the activation of LX-2,reduced eNOS and iNOS expression and increased α-SMA and CollagenⅠexpression,consistent with the role of TGF-β1.Simvastatin could directly increase the eNOS expression both in quiescent and activated LX-2 cells,decrease iNOS expression,maintain quiescent phenotype and inhibit its activation.ConclusionsSimvastatin ameliorated the genesis and progression of liver fibrosis by increasing eNOS expression in LX-2 cells and reducing iNOS,α-SMA and Collagen Ⅰ expression.