Melatonin alleviates memory deficits and neuronal degeneration induced by intracerebroventricular administration of streptozotocin in rats.

In the present study the effect of melatonin on intracerebroventricularly administered streptozotocin (STZ)-induced neurodegeneration was investigated in rats. STZ (3mg/kg), administered twice with an interval of 48 h between the two doses, showed impairment in spatial memory tested by water maze test after 14 days of 1st dose. Administration of melatonin (2.5, 5.0 and 10mg/kg, i.p.) was started 1h prior to 1st dose of STZ and continued up to 14 days. Glutathione and malondialdehyde were used as biochemical markers of oxidative stress in different brain regions. Histopathological changes were examined by using hematoxylin and eosin stain. STZ administration caused significant decrease in glutathione and increase in malondialdehyde as compared to control and artificial Cerebrospinal Fluid treated rats indicating oxidative stress. Brain sections of STZ-treated rats showed increased vacuoles in the periventricular cortical area, damaged periventricular cells and damaged cells in the hippocampal CA4 region as compared to control and artificial Cerebrospinal Fluid treated groups. Melatonin treatment significantly attenuated the effect of STZ-induced oxidative stress and histopathological changes. The results indicate that melatonin is effective in providing protection against memory deficit, oxidative stress and neuronal damage induced by STZ.