The effects of melatonin and curcumin on the expression of SIRT2, Bcl-2 and Bax in the hippocampus of adult rats

Objective: Though the mechanisms are not clearly understood, melatonin and curcumin have been reported to have neuroprotective effects. However, the mechanisms of neuroprotective effects of melatonin and curcumin in the brain are not clearly understood. In the current study, we investigated the effects of melatonin and curcumin treatments on oxidative stress parameters, the expression of SIRT2, Bcl-2 and Bax in the hippocampus. Methods: A total of thirty adult (13 months-old) male Wistar rats were divided into five groups: Control (1% ethanol:PBS), s.c. for 30 days), dimethyl sulfoxide (10%, s.c. for 30 days), Melatonin (10 mg/kg/day, s.c. for 30 days), Curcumin (30 mg/kg/day, i.p. for 30 days) and Salermide (100 mu M, i.p. for 30 days). The levels of malondialdehyde (MDA) glutathione (GSH) were measured as oxidative stress parameters in the hippocampus. The expression levels of SIRT2, Bcl-2 and Bax proteins were tested by western blotting and the SIRT2 protein levels of the hippocampal region was measured by a sandwich ELISA method. Results: Melatonin and curcumin significantly decreased MDA and SIRT2 expression in the hippocampus (p < 0.05). Accordingly, a significant increase in the GSH levels of curcumin-treated group and melatonintreated group was observed. Melatonin, but not curcumin, significantly increased the Bcl-2 expression of the hippocampal region. There was a significant correlation between SIRT2 and MDA levels (p < 0.05). Discussion: In conclusion, our results suggest that melatonin may increase cell survival in the hippocampus via decreasing oxidative stress and SIRT2 expression and increasing Bcl-2 expression.