Background: Few studies have investigated the possible ways to prevent lead induced defects during gestation and lactation. The aim of this study was to investigate the effect of melatonin as a hormone with antioxidant properties on oxidative stress in the hippocampus and learning and memory impairment induced by administration of lead.

Materials and Methods: Pregnant rats were exposed to treatments of control, lead acetate (0.2% solution in water), lead acetate + melatonin and melatonin (10 mg / kg by oral gavage) from gestation day 6 until weaning. 21 days after birth, the activities of several antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) as well as malondialdehyde levels in hippocampus of 23 male offspring rats were assayed. To behavioral studies, on postnatal day 30, 57 rats were trained 6 days in the Morris water maze and the probe test was performed 24 h later.

Results: The results showed that administration of lead during pregnancy and lactation could increase MDA levels and decrease glutathione peroxidase, superoxide dismutase and catalase antioxidant enzymes activities in the hippocampus of male offspring. Also, this treatment significantly disrupted performance of the Morris water maze test and impaired learning and spatial memory in male offspring compared with control. Administration of melatonin attenuated lipid peroxidation and could improve learning and spatial memory deficits and the activity of antioxidant enzymes in lead exposure group.

Conclusion: Melatonin as a neuropotective drug can protect the hippocampus against the complications of lead exposure, in the course of development.