protective effect of low dose melatonin on radiation-induced damage to rat liver

background: melatonin is a free radical scavenger. it has also antioxidant effects through its stimulatory actions on antioxidant system. objective: we conducted this study to examine the effect of different oral doses of melatonin on liver tissue. methods: we used 42 rats—6 rats in each group. group i served as the control group; group ii rats were pretreated with only melatonin; group iii was exposed to radiation only; and groups iv to vii were pretreated with different doses of melatonin (10, 100, 200, 400 μg/kg, respectively) and exposed to 6 gy whole body gamma irradiation. results: whole body irradiation induced liver tissue damage by increasing malondialdehyde (mda) concentrations and decreasing glutathione (gsh) levels. hepatic mda levels in irradiated rats that were pretreated with oral administration of melatonin in groups v, vi and vii, were significantly decreased, while the gsh levels were significantly increased. conclusion: oral administration of melatonin may prevent radiation-induced liver damage. this radio-protective effect is dose-dependent.