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 (1.14g/kg, 2.27g/kg, 4.53g/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-1, TGF receptor (TGFR)I, TGFRII, 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 approximate to 0.01), together with markedly prevented the upregulations of Collagen I and Collagen III (P<0.05 approximate to 0.01). Moreover, GXD downregulated expressions of TGF-1, TGFRI, TGFRII, 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-1 signalling pathway.