Postconditioning with NECA attenuates cardiac I/R injury by engaging A2AR-PKCα signaling in diabetic rat

Diabetes mellitus increases the heart's vulnerability to ischemia/reperfusion (I/R) injury and limits the efficacy of traditional cardioprotective interventions. This study evaluated the cardioprotective potential of 5'-N-ethylcarboxamido adenosine (NECA), a non-selective adenosine receptor agonist, in a diabetic rat model of myocardial I/R injury and explored the underlying molecular mechanisms. Type 2 diabetes was induced in Sprague-Dawley rats by high-fat diet feeding and streptozotocin injection. Myocardial I/R injury was established via 30-min coronary ligation followed by 2-h reperfusion. Rats were randomized into eleven treatment groups, including NECA, receptor modulators, and kinase regulators. Cardiac function and myocardial injury were assessed by echocardiography, TTC/Evans blue staining, histopathology, and plasma cardiac troponin I (cTnI) levels. NECA significantly improved left ventricular systolic function, reduced infarct size, and decreased cTnI release. These protective effects were associated with increased Bcl-2 expression and suppressed levels of cleaved caspase-3 and miR-15a. Pharmacological blockade of the A2A receptor with ZM241385 abolished NECA's benefits, while the A2AR agonist CGS21680 and PKCα activator PMA reproduced them. Electrophoretic mobility shift assays confirmed a direct interaction between PKCα and pri-miR-15a, suggesting transcriptional regulation. Collectively, these findings demonstrate that NECA attenuates myocardial I/R injury in diabetic rats through activation of the A2AR-PKCα signaling axis and inhibition of miR-15a, offering a potential therapeutic strategy for diabetic patients at risk of ischemic cardiac events.