Gualou Xiebai Decoction prevents myocardial fibrosis by blocking TGF-beta/Smad signalling

OBJECTIVES: The present study is aimed to investigate the effect of Gualou Xiebai Decoction (GXD) ethanol extract on myocardial fibrosis and clarify the possible mechanism. METHODS: Rats with ligated left anterior descending coronary artery were treated with GXD ethanol extract (1.14 g/kg, 2.27 g/kg, 4.53 g/kg) daily via gavage for 4 weeks. Histopathological changes and collagen distribution were evaluated by haematoxylin and eosin and Masson staining. The mRNA levels of Collagen I and Collagen III were detected by real-time PCR. The expressions of TGF-β1, TGFβ receptor (TGFβR)I, TGFβRII, P-Smad2/3 and Smad7 were determined by Western blot. RESULTS: GXD treatment was significantly reduced the heart weight/body weight ratio (P < 0.05) as well as the left ventricle weight/body weight ratio (P < 0.05). It also significantly alleviated the degree of inflammation, decreased myocardial collagen volume fraction (P < 0.05 ∼ 0.01), together with markedly prevented the upregulations of Collagen I and Collagen III (P < 0.05 ∼ 0.01). Moreover, GXD downregulated expressions of TGF-β1, TGFβRI, TGFβRII, Smad2/3 whereas improved Smad7 expression in the myocardial fibrosis rats. CONCLUSIONS: GXD ameliorates myocardial fibrosis induced by cardiac infarction with ligated left anterior descending coronary artery, the mechanism maybe involve in inhibiting the TGF-β1 signalling pathway.