Hesperetin Postconditioning Protects From Myocardial Ischemia/Reperfusion Injury By Regulating Autophagy And Apoptosis

Timely recovery of acute myocardial infarction(AMI)patients with coronary blood flow is the basic measurement to save ischemic myocardium,but it also causes myocardial reperfusion injury at the same time.Autophagy is widely found in eukaryotic cells,which is the process of cellular self-digestion and renewal.Autophagy plays an important role in myocardial ischemia/reperfusion(I/R)-induced injury.Hesperidin(HES),which extracts from citrus fruit,has protective effects on ischemia/reperfusion injury in different organs.Hesperetin(HPT)is the active metabolite of hesperidin,has a strong anti-inflammatory,anti-oxidation and anti-tumor effects.In addition,previously study reported that HPT has potential anti-thrombotic effect in the cardiovascular system.However,the role and mechanism of hesperidin or hesperetin in myocardial ischemia/reperfusion injury has not been reported.In this study,We utilized an in vivo mouse model of myocardial I/R injury and an in vitro neonatal rat cardiomyocyte(NRC)model of hypoxia/reoxygenation(H/R)injury.I/R injury was simulated by ligating the left anterior descending artery of the coronary artery for 30 min,then the ligation line was relieved to restore blood flow for 120 min.NRCs received hypoxia 3 h followed reoxygenation for 3 h.The myocardial infarct size of C57BL/6 mice was measured by TTC/Evans blue staining.The cell viability of primary cardiomyocytes in neonatal SD rats was determined by MTS.The number of autophagosomes and the ultrastructural changes of mitochondria were observed by transmission electron microscopy(TEM).The autophagic marker protein LC3 was detected by immunofluorescence staining.Detection of Autophagy and Apoptosis proteins by Western blot.HPT post-treatment decreased in the myocardium infarct size;decreased LC3B ?,LC3B ?/? ratio,and Beclinl,however,increased p62;decreased the number of autophagosomes;Immunofluorescence staining showed decreased LC3.These results suggested that HPT post-treatment protected against myocardial I/R injury and inhibits autophagy during I/R injury.On the basis of these,we further explored the specific signal pathway of autophagy.Western blot showed that the phosphorylation level of PI3K,Akt and mTOR protein increased by adding LY294002 or BEZ235(specific inhibitor of PI3K/Akt pathway),which suggested that the inhibition of autophagy of hesperetin was partially blocked.In summary,we boldly believed that hesperetin postconditioning protects from myocrdial ischemia/reperfusion injury by regulating autophagy through activating PI3K/Akt/mTOR signaling pathway.