Objective:To investigate the role and mechanisms of cellular FLICE-like inhibitory protein (cFLIP) in mediating oxidative stress induced by myocardial ischemia-reperfusion injury (MI/RI) in rats.Methods:Forty-eight male Sprague-Dawley rats with body weight of 180-200 g, were randomly divided into 4 groups ( n=12 per group) using a random number table: sham operation group (sham group), ischemia-reperfusion group (I/R group), virus control group (I/R+Ad-NC group), and cFLIPL-overexpressing group (I/R+Ad-cFLIPL group). A myocardial ischemia-reperfusion injury (MI/RI) model was established by ligating the left anterior descending coronary artery for 30 min followed by 3 h of reperfusion. The left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in rats were evaluated via echocardiography, and a biochemical analyzer was used to measure the serum lactate dehydrogenase (LDH) and creatine kinase isoenzyme (CK-MB) levels to evaluate the extent of myocardial injury. The 2,3,5- triphenyl tetrazolium chloride (TTC) staining method was used to detect the infarct area of the rat myocardium, and hematoxylin and eosin (HE) staining was performed to observe the morphology of the rat myocardial tissue. Commercial kits were used to measure the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-px), and malondialdehyde (MDA). Dihydroethidium (DHE) staining was used to assess the number of reactive oxygen species (ROS)-positive cells in the myocardial tissue. Western blot analysis was performed to evaluate the protein expression of cFLIPL, Nrf2, and HO-1. Results:During MI/RI, compared with the sham group, the protein expression of cFLIPL was significantly decreased in the I/R group, and compared with the I/R+Ad-NC group, the protein expression of cFLIPL was significantly increased in the I/R+Ad-cFLIPL group (both P<0.05). Compared with sham group, the level of LDH, CK-MB, MDA, ROS-positive cell count, and myocardial infarct size were significantly increased, whereas the LVEF, LVFS, SOD, and GSH-px were significantly decreased in I/R group (all P<0.05). Compared to the I/R+Ad-NC group, the level of LDH, CK-MB, MDA, ROS-positive cell count, and myocardial infarct area were significantly decreased, whereas the LVEF, LVFS, SOD, and GSH-px were significantly increased in I/R+Ad-cFLIPL group (all P<0.05). Western blot revealed that compared with the sham group, the protein expression of Nrf2 and HO-1 in I/R group were significantly increased, and compared with the I/R+Ad-NC group, the protein expression of Nrf2 and HO-1 in the I/R + Ad-cFLIPL group were significantly increased (all P<0.05). Conclusion:Overexpression of cFLIPL can alleviate myocardial ischemia-reperfusion injury (MI/RI) in rats by activating the Nrf2/HO-1 signaling pathway to inhibit oxidative stress.