Promising though not yet proven: Emerging strategies to promote myocardial salvage

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.

Beneficial effects of the extract from Corydalis yanhusuo in rats with heart failure following myocardial infarction

As indicated in ancient Chinese medical books, Corydalis yanhusuo has therapeutic effects on cardiovascular diseases. The analgesic effect of this plant has been fully elucidated, and I-tetrahydropalmatine has been shown to be the main active principle. The aim of this investigation was to evaluate its protective effects in a rat heart failure model. Rats were subjected to coronary artery ligation, and orally administered with ethanolic extract of Corydalis yanhusuo 50, 100, or 200 mg kg−1 daily, from the 7th day after surgery. We measured cardiac function, plasma atrial natriuretic peptide (ANP), relative heart and lung weights, infarct size and ventricular dilatation after treatment for 8 weeks. Administration with Corydalis yanhusuo led to a significant reduction in infarct size and improvement in cardiac function as demonstrated by lower left ventricular end diastolic pressure (LVEDP) and elevated ± dp/dtmax. We also found that Corydalis yanhusuo significantly reduced left ventricular (LV)/body weight ratio, lung/body weight ratio and significantly inhibited neurohormonal activation. Taken together, this study indicated that Corydalis yanhusuo exerted salutary effects on heart failure induced by myocardial infarction in rats.

Salutary effects of Corydalis yanhusuo extract on cardiac hypertrophy due to pressure overload in rats

We have evaluated the effects of an alcohol extract from the rhizome of Corydalis yanhusuo W.T. (CY), a well-known traditional Chinese medicinal herb, on pressure-overloaded cardiac hypertrophy induced by transverse abdominal aorta constriction (TAAC) in rats. Rats were given vehicle or CY extract (200 or 50 mg kg−1 per day) from the second week after induction of pressure overload, for a period of 7 weeks. Haemodynamic parameters, relative heart weight and myocyte cross-sectional area were measured in each group. We also estimated left ventricular (LV) collagen volume fraction (CVF) using Masson trichrome staining, and type I collagen expression by Western blot assay. Chronic TAAC caused notable cardiac hypertrophy and heart dysfunction. Significant collagen deposition and greater type I collagen expression were found in model control rats. These changes were not significantly reversed after treatment with 50 mgkg−1 CY, whereas 200 mgkg−1 significantly improved heart function and prevented cardiac hypertrophy, with parallel reductions in myocardial fibrosis, as evidenced by reduced LV CVF and reduced levels of type I collagen. In conclusion, chronic treatment of rats with CY extract attenuated development of cardiac hypertrophy.