Koc, M., Taysi, S., Buyukokuroglu, M. E. and Bakan, N. The Effect of Melatonin against Oxidative Damage during Total-Body Irradiation in Rats. Radiat. Res. 160, 251–255 (2003).
Melatonin has been reported to participate in the regulation of a number of important physiological and pathological processes. Melatonin, which is a powerful endogenous antioxidant, may play a role in the prevention of oxidative damage. The aim of this study was to investigate the effect of pretreatment with melatonin (5 mg kg–1 and 10 mg kg–1) on γ-radiation-induced oxidative damage in plasma and erythrocytes after total-body irradiation with a single dose of 5 Gy. Total-body irradiation resulted in a significant increase in plasma and erythrocyte MDA levels. Melatonin alone increased the levels of SOD and GSH-Px. Erythrocyte and plasma MDA levels in irradiated rats that were pretreated with melatonin (5 or 10 mg kg–1) were significantly lower than those in rats that were not pretreated. There was no significant difference between the effects of 5 and 10 mg kg–1 on plasma MDA activities and CAT activities. However, erythrocyte MDA levels showed a dose-dependent decrease, while GSH-Px activities increased with dose. Our study suggests that melatonin administered prior to irradiation may protect against the damage produced by radiation by the up-regulation of antioxidant enzymes and by scavenging free radicals generated by ionizing radiation.