Protective effect of melatonin on injuried cerebral neurons is associated with bcl-2 protein over-expression

AIM: To study the protective effect of melatonin against neuronal injury an d the possible roles of alteration in the expression of bcl-2 and bar follo wing brain ischemia. METHODS: Brain ischemia was induced by left middle cer ebral artery occlusion (MCAO) for 60 min in rats. Blain damage was evaluate d by the infarct area and the neuronal cell counting. The expression of bcl -2 and bar was analyzed by immunohistochemical method. RESULTS: Melatonin d ecreased the infarct area and prevented the neuronal death after 24-h reper fusion following I-h MCAO. Melatonin given before the ischemia enhanced the expression of bcl-2 in the penumbra area and had no significant effect on the expression of bax. CONCLUSION: Melatonin effectively attenuated ischemi c brain injury and increased the expression of neuronal bcl-2 in the ischem ic brain, indicating that the protective effect of melatonin was associated with up-regulation of bcl-2 in ischemia-induced neuronal death.