Melatonin attenuates renal ischemia–reperfusion injury in nitric oxide synthase inhibited rats

Summary studies show that melatonin reduces the blood pressure (BP) and ischemia/reperfusion (I/R)-induced damage. This study was designed to investigate the effects of melatonin on the renal I/R injury in rats given the nitric oxide synthase (NOS) inhibitor, Nω-nitro-l-arginine methyl ester (l-NAME). After right nephrectomy, I/R was induced by occlusion of the left renal vessels for 60 min, followed by 24 h reperfusion. The administration of melatonin significantly attenuated BP in NOS-inhibited hypertensive rats. Malondialdehyde (MDA) levels, a stable metabolite of the free-radical-mediated lipid peroxidation cascade, were found to be significantly higher in the I/R group (3.48±0.2 mg/l serum) than in the control group (2.69±0.2 mg/l serum). l-NAME (40 mg kg−1 for 15 days)+I/R significantly increased the MDA levels compared to I/R alone. Melatonin administration to l-NAME rats significantly reduced the MDA values resulting from I/R. We also demonstrated that I/R, and especially l-NAME+I/R, lead to structural changes in the kidney and that melatonin attenuates these changes. These results suggest that melatonin reduces BP and I/R injury in NOS inhibited rats by l-NAME.