Astragalus and Paeoniae radix rubra extract inhibits liver fibrosis by modulating the transforming growth factorβ/Smad pathway in rats

Abstract

It has been previously demonstrated that Astragalus and Paeoniae radix rubra extract (APE) had a protective effect against liver fibrosis in mice. The present study aimed to investigate the hepatoprotective effect of APE on CCl4 induced hepatic fibrosis in rats. Liver fibrosis was induced in male SpragueDawley rats by intraperitoneal injection of 50% CCl4 twice a week for eight weeks. Organ coefficients, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), hexadecenoic acid (HA), laminin (LN), procollagen type III (PCIII), hydroxyproline (Hyp), glutathione (GSHPx), malondialdehyde (MDA), superoxide dismutase (SOD) and transforming growth factor β1 (TGFβ1) levels were measured in rats with hepatic fibrosis. Histopathological changes in affected livers were studied using hematoxylineosin and Masson's trichrome staining. The expression of transforming growth factorβ/Smad pathway proteins, α smooth muscle actin (α SMA), collagen I and collagen III was observed in fibrotic livers using western blot analysis. The present study observed significant reductions in serum levels of AST, ALT, HA, LN, PCIII and Hyp in APEtreated (2.6 and 5.2 g/kg) rats, indicating the significant hepatoprotective effects of APE. Furthermore, the depletion of GSHPx and SOD, in addition to the accumulation of MDA in liver tissue was suppressed by APE (2.6 and 5.2 g/kg). Pathological assessment of CCl4-induced fibrotic livers revealed a significant reduction of liver injury and development of hepatic fibrosis in rats treated with APE (2.6 and 5.2 g/kg). Moreover, APE (2.6 and 5.2 g/kg) decreased the elevation of TGFβ1, α SMA, collagen I and collagen III expression, inhibited Smad2/3 phosphorylation as well as elevated the expression of the TGFβ1 inhibitor Smad7. These results suggested that APE may protect against liver damage and inhibit the progression of CCl4 induced hepatic fibrosis. The mechanism of action of APE is hypothesized to proceed via scavenging free radicals, decreasing TGFβ1 levels and blocking of the TGFβ/Smad signaling pathway.