Role of nuclear factor-erythroid 2-related factor 2 in diabetic rats with resveratrol preconditioning against myocardial isch- emia-reperfusion injury

Abstract

Objective To observe the effect of nuclear factor-erythroid 2-related factor 2 (Nrf2) in diabetic rats preconditioning with resveratrol (Res) against myocardial ischemia/reperfusion injury (MI/RI). Methods Healthy adult male SD rats weighing 200- 220 g and aged from 4 to 5 months were fed with high-fat diet for 4 weeks and then intraperitoneally injected with streptozotocin (STZ) 30 mg/kg to establish a diabetic rat model. Thirty successfully modeled rats were divided into three groups according to a random number table (n=10): a sham operation group (a Sham group), a myocardial ischemia/reperfusion group (an MI/R group) and a myocardial ischemia/reperfusion+resveratrol group (an MI/R+Res group). A rat model of MI/RI was established by ligation of the left anterior descending coronary artery for 30 min before reperfusion for 120 min. In the MI/R+Res group, 15 mg/kg Res was intraperitoneally injected 7 d before establishment of the MI/RI model, once a day for 7 consecutive days. The Sham and MI/R groups were intraperitoneally injected with an equal volume of dimethyl sulfoxide (DMSO) and PBS mixture. Left ventricular ejection fraction (LVEF) and left ventricular short axis shortening (FS) were measured by B-mode ultrasonography. Five rats were sacrificed 120 min after reperfusion. Myocardial infarction size was measured by 2, 3, 5-triphenyl-2H-tetrazolium chloride (TTC) staining. Another five rats were sacrificed to collect blood samples from the abdominal aorta for measurement of lactate dehydrogenase (LDH), a marker of myocardial injury, and creatine kinase isoenzyme (CK-MB). Their myocardial tissues were collected to determine the levels of superoxide dismutase(SOD), malondialdehyde (MDA) and reactive oxygen species (ROS) by enzyme-linked immunosorbent assay (ELISA). The contents of Nrf2 were observed by immunohistochemistry. The expression of Nrf2, n-Nrf2 and heme oxygenase-1 (HO-1) were determined by Western blot. Results Compared with those in the Sham group, LDH, CK-MB concentration, ROS and MDA content in the MI/R and MI/R+ Res groups significantly increased while LVEF, FS, and SOD activity in the MI/R and MI/R+Res groups significantly decreased. Mean-while, the myocardial infarction sizes in the MI/R and MI/R+Res groups were increased, and the expression of Nrf2, n-Nrf2 and HO-1 protein was down-regulated (all P<0.05). Compared with those in the MI/R group, LDH, CK-MB concentration, ROS and MDA content significantly decreased in the MI/R+Res group, while LVEF, FS and SOD activity significantly increased in the MI/R+Res group. Also, in the MI/R+Res group, the myocardial infarction size decreased while the expression of Nrf2, n-Nrf2 and HO-1 protein increased (all P< 0.05). Conclusions Resveratrol preconditioning relieves myocardial injury in diabetic rats with ischemia/reperfusion, which may attribute to activation of Nrf2. Key words: Resveratrol; Transcription factor-related factor 2; Heme oxygenase-1; Diabetes; Myocardial ischemia/reperfusion