Résumé
The present study investigated the effects of chikusetsu saponin Ⅳa(CHS Ⅳa) on isoproterenol(ISO)-induced myocardial hypertrophy in rats and explored the underlying molecular mechanism. ISO was applied to establish a rat model of myocardial hypertrophy, and CHS Ⅳa(5 and 15 mg·kg~(-1)·d~(-1)) was used for intervention. The tail artery blood pressure was measured. Cardiac ultrasound examination was performed. The ratio of heart weight to body weight(HW/BW) was calculated. Morphological changes in the myocardial tissue were observed by HE staining. Collagen deposition in the myocardial tissue was observed by Masson staining. The mRNA expression of myocardial hypertrophy indicators(ANP and BNP), autophagy-related genes(Atg5, P62 and beclin1), and miR199 a-5 p was detected by qRT-PCR. Atg5 protein expression was detected by Western blot. The results showed that the model group exhibited increased tail artery blood pressure and HW/BW ratio, thickened left ventricular myocardium, enlarged myocardial cells, disordered myocardial fibers with widened interstitium, and a large amount of collagen aggregating around the extracellular matrix and blood vessels. ANP and BNP were largely expressed. Moreover, P62 expression was up-regulated, while beclin1 expression was down-regulated. After intervention by CHS Ⅳa at different doses, myocardial hypertrophy was ameliorated and autophagy activity in the myocardial tissue was enhanced. Meanwhile, miR199 a-5 p expression declined and Atg5 expression increased. As predicted by bioinformatics, Atg5 was a target gene of miR199 a-5 p. CHS Ⅳa was capable of preventing myocardial hypertrophy by regulating autophagy of myocardial cells through the miR-199 a-5 p/Atg5 signaling pathway.