Objective: The aim of this study was to evaluate the protective effects of the melatonin on the cadmium induced oxidative damage in rat liver.

Material and Method: Twenty-one male Wistar-Albino rats were included into the study. Animals were divided into three equal groups: Group 1; control, Group 2; cadmium chloride (CdCl₂) and Group 3; CdCl₂+melatonin group. Rats in Group 1 were injected by saline solution subcutaneously for 30 days. Rats in Group 2 were injected by cadmium chlorur (1mg/kg) subcutaneously for 30 days. Rats in Group 3 were injected by subcutaneous CdCl₂+ intraperitoneal melatonin (25mg/kg) for 30 days. Rats in all groups were decapitated and liver samples were examined biochemically and by light microscopy.

Results: In CdCl₂ treated group, liver superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels were significantly lower and malondialdehyde (MDA) levels were significantly higher than the control group (p<0.05). CdCl₂ + melatonin treatment resulted in a statistically significant increase in SOD and GSH-Px enzyme activities, and a decrease in MDA levels than cadmium chloride (group 2) (p<0.05). Microscopically some histopathological changes, namely fatty degeneration, hydropic degeneration, fibrosis and mononuclear cell infiltration were observed in the livers of the cadmium treated rats. Same histopathologies were not observed in rats treated by CdCl2 + melatonin.

Conclusion: It is concluded that cadmium creates oxidative damage in rat liver and melatonin has protective effects against this cadmium induced damage.