Activation of AMPK/p38/Nrf2 is involved in resveratrol alleviating myocardial ischemia-reperfusion injury in diabetic rats as an endogenous antioxidant stress feedback

BACKGROUND: Myocardial necrosis caused by myocardial ischemia-reperfusion (MI/R) in diabetic patients is prominently aggravated and can cause oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensing transcription factor that protects against myocardial ischemia/reperfusion injury (MIRI). However, the mechanism of action of Nrf2 in resveratrol-pretreated cardiomyocytes is complex. We assumed that adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/p38 mitogen-activated protein kinases (p38)/Nrf2 might be involved in resveratrol alleviating MIRI in diabetic rats as an endogenous protective mechanism. METHODS: A total of 50 type 2 diabetes mellitus (T2DM) rat models were randomly divided into 5 groups (n=10 in each group): sham group; MI/R group; AMPK inhibitor compound C + myocardial ischemia-reperfusion (C + MI/R) group; resveratrol + myocardial ischemia-reperfusion (RSV + MI/R) group; and resveratrol + AMPK inhibitor compound C + myocardium ischemia-reperfusion group (RSV + C + MI/R) group. Rats were fed a high fat diet, and the T2DM models were established by intraperitoneal injection of 1% streptozotocin (STZ). The MIRI models were established by ligating the left anterior descending coronary artery for 30 minutes followed by reperfusion for 120 minutes. The size of myocardial infarction was measured. Serum samples were collected to measure the concentrations of creatine kinase-MB (CK-MB). The levels of lactate dehydrogenase (LDH), glutathione (GSH), and superoxide dismutase (SOD) in myocardial tissues were determined. Immunofluorescence analysis of translocase of outer mitochondrial membrane 20 (TOMM20) was performed to observe the pathological changes in myocardial tissues. The protein expressions of AMPK, p-AMPK, p38, p-p38, Nrf2, and heme oxygenase 1 (HO-1) were determined by western blotting. RESULTS: Compared with the sham group, the expressions of AMPK, p38, Nrf2, and HO-1 in the myocardium were significantly increased in the MI/R group. Compared with the MI/R group, the RSV + MI/R group had a significantly lower oxidative stress level, milder myocardial injury, increased expressions of AMPK, Nrf2, and HO-1, and lower expression of p38. The protein expressions of Nrf2 and HO-1 were partially inhibited in the RSV + C + MI/R group. CONCLUSIONS: Resveratrol can inhibit oxidative stress and alleviate MIRI by activating the AMPK/p38/Nrf2 signaling pathway. Meanwhile, AMPK/p38/Nrf2 is also an endogenous antioxidant stress pathway that protects against stress.