Abstract
Myocardial infarction (MI) is a myocardial injury caused by coronary thrombosis or persistent ischemia and hypoxia. Due to its high morbidity and mortality, a safer and more effective treatment strategy is urgently needed. Daming capsule (DMC), a hypolipidemic drug, reportedly exerts cardioprotective effects in clinical and basic research, although its protective mechanism remains unknown. To investigate the mechanism underlying DMC-mediated improvement of cardiac function post-MI, C57/BL6 mice subjected to coronary artery ligation were administered DMC for 4 weeks. Our data demonstrated that DMC significantly improved cardiac structure and function compared to the saline group. Moreover, DMC inhibited inflammatory response and oxidative stress and improved mitochondrial structure and function in MI mice and hypoxia-stressed cardiomyocytes. Next, our research proved that DMC increased the expression of mitophagy receptor NLRX1. Interestingly, with the administration of DMC and siNLRX1, NLRX1 expression, mitochondria and lysosome colocalization, and mitochondrial membrane potential decreased, while mitochondrial ROS accumulation increased, suggesting that DMC promoted mitophagy to improve mitochondrial function via NLRX1 regulation. Further analysis showed that DMC activated the SIRT1/AMPK signaling pathway in vivo and in vitro. Our data showed that SIRT1 knockdown downregulated NLRX1 expression, leading to structural damage and functional impairment in mitochondria, as well as increased oxidative stress, inflammatory response, and decreased cardiac function in MI mice. Collectively, our findings reveal that DMC improves cardiac function post-MI by increasing mitophagy and inhibiting oxidative stress and inflammotory response in cardiomyocytes through the SIRT1/AMPK signaling pathway.