Protective effects of total glucosides of paeony and the underlying mechanisms in carbon tetrachloride-induced experimental liver injury

INTRODUCTION: We explored the protective effects of total glucosides of paeony (TGP) and the underlying mechanisms in carbon tetrachloride (CCl(4))-induced experimental liver injury in mice. MATERIAL AND METHODS: Chronic liver damage was induced by intraperitoneal injection of CCl(4) (0.5 µl/g) three times per week for 8 weeks. Mice also received 25, 50 or 100 mg/kg TGP. Liver sections were stained with haematoxylin/eosin. Serum amino transferases, lipid peroxidation and tumour necrosis factor-α (TNF-α) levels were determined using commercial assays. Quantitative real-time polymerase chain reaction was used to determine the changes in hepatic TNF-α, COX-2, iNOS and HO-1 expression. Protein levels of nitric oxide synthase, cyclooxygenase-2, haem oxygenase-1 and cytochrome P450 2E1 were determined by western blotting. RESULTS: Histological results showed that TGP improved the CCl(4)-induced changes in liver structure and alleviated lobular necrosis. The increases in serum protein and hepatic mRNA expression of TNF-α induced by CCl(4) treatment were suppressed by TGP. Total glucosides of paeony also attenuated the increase the expression in iNOS and CYP2E1 but augmented the increase in HO-1.The mRNA and protein expression levels of inducible HO-1 increased significantly after CCl(4) treatment. CONCLUSIONS: Total glucosides of paeony protects hepatocytes from oxidative damage induced by CCl(4). Total glucosides of paeony may achieve these effects by enhancing HO-1 expression and inhibiting the expression of proinflammatory mediators.