Imperatorin ameliorates myocardial ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress-mediated apoptosis via the PI3K/AKT/Nrf2 pathway.

Abstract

Endoplasmic reticulum stress (ERS) is a major event associated with myocardial ischemia-reperfusion injury (MIRI). Imperatorin (IMP) has cardioprotective effects, but its role in MIRI has not been reported. H9c2 cells were injured by the hypoxia/reoxygenation (H/R) method. The MIRI mouse model was prepared by coronary artery ligation and by using IMP, and the PI3K/AKT agonist 740 Y-P and inhibitor LY294002 were used for intervention. Cardiomyocyte apoptosis was determined through flow cytometry and TUNEL staining. Western blot, transmission electron microscopy, calcium assay kits, and Fluo-4 AM fluorescent probe were used to evaluate ERS and Ca²⁺ levels. In addition, the PI3K/AKT/Nrf2 pathway protein expressions were detected. IMP could significantly reduce cardiomyocyte apoptosis in H9c2 cells and myocardial tissue of MIRI mice, reduce ER swelling and damage, restore ER membrane structure, and reduce Ca²⁺ content and Caspase 12 and C/EBP homologous protein (CHOP) protein levels. IMP also increased p-PI3K and p-AKT proteins and the nuclear translocation of Nrf2 in H9c2 cells and myocardial tissue of MIRI mice. After IMP treatment combined with 740 Y-P intervention, the effect of IMP on improving cardiomyocyte apoptosis and ERS was further promoted, and the apoptosis rate, Ca²⁺ content, and caspase 12 and CHOP protein levels were significantly reduced. LY294002 weakened the improvement of IMP, and apoptosis and ERS levels increased significantly. IMP attenuated MIRI by inhibiting ERS and myocardial apoptosis through activating the PI3K/AKT/Nrf2 pathway.