The role of melatonin in prevention of intestinal ischemia-reperfusion injury in rats

Background/Purpose: The aim of this study was to determine the effect of me latonin, a hormone that is known as an antioxidant, on the prevention of ti ssue damage during mesenteric ischemia/reperfusion (I/R). Methods: A total of 40 young Wistar-al bi no rats were divided equally into 4 groups with varied treatment. Group 1 was control (sham), group 2 was I/ R, group 3 was I/R plus melatonin (10 mg/kg) and group 4 was I/R plus melat onin (20 mg/kg). I/R was realized as follows: after laparatomy, a microvasc ular atraumatic clip was placed across the superior mesenteric artery (SMA) under general anaesthesia, and it was removed after ischemia for 30 minute s. The first dose of melatonin was applied intraperitoneally at the start o f reperfusion, The second and third doses were applied intramuscularly on t he first and second day. Only SMA dissection under general anaesthesia was carried out in the control group rats. On the third day of the study all th e rats were killed, and their bowels were removed. Malondialdehyde (MDA) le vels were assayed as an index of lipid peroxidation reflecting free radical reaction in the intestine. Histopathologic analysis was made using light m icroscopy in a blind fashion. Results: The levels of tissue MDA were found to be significantly lower in g roups 3 and 4 compared with group 2 (P > .05). The MDA levels of group 4 di d not differ significantly from that of the control group (P > .05). The hi stopathologic results were consistent with the MDA levels, Conclusion: These results suggest that melatonin has a strong antioxidant e ffect in preventing intestinal I/R damage, and that this effect is exerted in a dose-dependent manner. J Pediatr Surg 35:1444-1448. Copyright (C) 2000 by W.B. Saunders Company.