Objective: Many factors can have a neuroprotective role after brain damage. The neuroprotective Effect of melatonin as a highly potent antioxidant and a free radical scavenger is well known. The purpose of this study was to investigate the effect of such melatonin on mice sensorimotorcortex after cold injury.

Materials & Methods: In order to test such this objective, melatonin was injected intraperitoneally in 1,5,50 and 100 mg/kg to the mice (prepared by cortical cold injury induced brain lesion at the parietal lobe) within three intervals (0.5 h before injury, 12 h and 48 h after injury). Brains were removed 72 hours after injury. Appropriate brain sections were stained with cresyl fast violet for histological assessment of cerebral cortex structures by using light microscope (LM).

Results: After cell count of alive cells in the cerebral cortex the results showed that the cold injury caused significantly reduction in living cells. Melatonin administration in the experimental groups increased such living cells in compare to model group. Alive cells in cerebral cortex of animals which received melatonin at lower doses (1 and 5 mg/kg) were lower than the control group, melatonin at optimum dose (50 mg/kg) did not show any significant change in the number of alive cells in comparing with the control group (P>0/05). The highest dose (100mg/kg) was toxic.

Conclusion: Melatonin with optimum dose can reduce cerebral cortex damage due to cold injury in mouse model and overcome cell damages fallowing injury.