Er-xian ameliorates myocardial ischemia-reperfusion injury in rats through RISK pathway involving estrogen receptors

Curculigo orchioides (CUR) and Epimedium (EPI) are traditional Chinese medicines with estrogen-like biological activity, called Xianmao and Xianlingpi (Er-xian) in Chinese. However, whether Er-xian exerts protective effects on myocardial ischemia-reperfusion injury (MIRI) is unknown. This study aimed to investigate the cardioprotective effects of Er-xian preconditioning against MIRI and the underlying mechanisms. CUR or EPI was administered intragastrically to aged female rats as a monotherapy or combination therapy. 2 weeks later, a rat MIRI model was established. Myocardial infarction size, myocardial morphology, cTnT, cell apoptosis rate, intracellular calcium concentration, mitochondrial permeability transition pore (MPTP) opening and reperfusion injury salvage kinase (RISK) signaling pathway molecules were observed after the surgery. To evaluate the mechanisms of Er-xian, estrogen receptors antagonists ICI 182780 and G15 were used. In this study, Er-xian notably alleviated myocardial tissue damage, maintained mitochondrial morphology, reduced infarct size and cardiac markers, and increased sera levels of E2. Moreover, Er-xian inhibited calcium overload and mPTP opening, and decreased cardiomyocyte apoptosis. We found that the dual therapy of CUR and EPI elicited more noticeable results than CUR or EPI monotherapy. The significant protective effects of Er-xian on ischemia-reperfusion myocardium were attributed to the up-regulation of AKT, ERK1/2 and GSK-3β phosphorylation levels. The cardioprotective effects of Er-xian were significantly reduced after estrogen receptor blockade, especially GPER30. These results indicate that Er-xian attenuates MIRI through RISK signaling pathway and estrogen receptors are the critical mediators.