Study On The Molecular Mechanism Of The Inhibition Of Extracts Of Marsdenia Tenacissima On Hepatic Fibrosis In Rats

Objective:Study on the effects and molecular mechanism of extracts of Chinese medicine Marsdenia Tenacissima on liver fibrosis in rats induced by carbon tetrachloride（CCl₄）.Methods:Sixty SD rats were randomly divided into normal control group,model group,SMT low dose group(10 mg.kg^-1)and SMT high dose group(40 mg.kg^-1),with 15 rats in each group.Liver fibrosis model of rat was prepared by subcutaneous injection of CCl4 at 0.3 mL·100 g^-1,twice a week for 12 weeks.After 4 weeks of modeling,the drug-administered groups were intragastrically administered with the corresponding dose of the drug（SMT）,while the normal control group and the model group were given the same amount of physiological saline.After 12 weeks,rats were killed and determination of the amount of ALT,AST,SOD,MDA,GSH-px,HA,LN and CIV in serum were detected by ELISA assay.The pathological changes of liver tissue in rats were observed by HE staining,and the changes of liver collagen deposition were observed by Masson staining.The protein expression levels ofα-SMA,p-smad2,p-smad3,p-p38MAPK and p-PI3K in liver tissues were detected by western blot.Results:Pathological results show the liver cells of the normal group were arranged neatly and radially,showing intact hepatic lobular structure and central vein,no obvious inflammatory and necrotic features and fibrous tissue hyperplasia.Significant cell degeneration,necrosis and steatosis were observed in the liver of the model group,and significant collagen deposition and hepatocyte loosening were observed by Masson staining.The liver pathology of rats in each dose group of SMT was significantly improved compared with the model group.The degree of hepatocyte necrosis and inflammatory cell infiltration was significantly reduced,and the collagen deposition in the portal area was reduced,especially in the SMT high dose group.Serological indicators showed that compared with normal group,serum ALT,AST,MDA,HA,LN and C-IV levels were significantly increased in model rats（P<0.01）,while SOD,GSH-Px levels were decreased significantly（P<0.01）.Compared with model group,the levels of ALT,AST,MDA,HA,LN and CIV in the SMT low-dose group and the SMT high-dose group were significantly decreased（P<0.01）,while SOD,GSH-Px levels were increased significantly（P<0.01）,there was a concentration-response relationship.Western blot showed that the expression levels ofα-SMA,p-Smad2,p-Smad3,p-p38MAPK and p-PI3K in the liver of the model group were significantly higher than those in the normal group（P<0.01）.Compared with the model group,the expression levels ofα-SMA,p-Smad2,p-Smad3,p-p38MAPK,and p-PI3K protein in SMT low-dose group and SMT high-dose group were significantly lower,and the difference was statistically significant（P<0.01）.Conclusion:SMT can significantly inhibit the liver fibrosis induced by CCl₄ in rats.It can alleviate the pathological damage of liver in model rats,reduce the serum ALT,AST,HA,LN and CIV levels and the expression level ofα-SMA protein in liver tissue,the mechanism may be related to its regulation of liver TGF-β/smads,PI3K/Akt and MAPK signal transduction pathways.This study can provide new ideas,theoretical and experimental basis for the prevention and treatment of liver fibrosis.