Oxytocin ameliorates high glucose- and ischemia/reperfusion-induced myocardial injury by suppressing pyroptosis via AMPK signaling pathway

The present study aimed to explore the role of oxytocin (OT) in myocardial injury induced by ischemia/reperfusion (I/R) and hyperglycemia and its underlying mechanisms. In this study, the isolated rat hearts underwent I/R in Langendorff perfusion model and H9c2 cells were subjected to hypoxia/reoxygenation (H/R) to establish an in vitro model. I/R injury was induced by exposing the rat hearts to 40 min of global ischemia followed by 60 min of reperfusion. H9c2 cells were cultured under the normoglycemic or hyperglycemic condition with or without pretreatment of OT, and then exposed to 4 h of hypoxia and 2 h of reoxygenation. Measurement indicators included myocardial infarct size assessed by triphenyltetrazolium chloride (TTC) staining and hemodynamic parameters in the ex vivo model as well as cell viability detected by cell counting kit 8 (CCK-8), apoptotic rate evaluated by flow cytometry, and the protein expressions by Western blot. The findings demonstrated that OT attenuated myocardial I/R injury. First, OT preconditioning significantly reduced hemodynamic disorders and myocardial infarct sizes. In addition, OT increased cell viability, decreased cell apoptosis and the expressions of IL-18, IL-1β, cleaved-caspase-1, NLRP3, and GSDMD following H/R. NLRP3 activator nigericin eliminated the beneficial effects of OT in H9c2 cells. Furthermore, OT also activated AMPK and decreased the expressions of pyroptosis-related proteins. Administration of AMPK inhibitor compound C blunted OT-induced AMPK phosphorylation and elevated the expressions of pyroptosis-related proteins in H9c2 cells subjected to H/R with hyperglycemia. OT alleviates myocardial I/R injury with hyperglycemia by inhibiting pyroptosis via AMPK/NLRP3 signaling pathway.