Enhanced behavioral response by decreasing brain oxidative stress to 6-hydroxy-l-nicotine in Alzheimer's disease rat model.

6-Hydroxy-l-nicotine (6HLN) is a nicotine metabolite resulted from nicotine degradation within Arthrobacter nicotinovorans with positive effects on spatial memory and oxidative stress damage. In the present study, the effects of 6HLN on spatial memory performance were assessed in scopolamine-treated rats. Scopolamine-induced memory impairments were observed, as measured by the Y-maze and radial arm-maze tasks. Decreased activities of superoxide dismutase, glutathione peroxidase and catalase along with decrease of total content of reduced glutathione were observed in the rat hippocampal homogenates of scopolamine-treated animals as compared with control. Production of malondialdehyde (lipid peroxidation) significantly increased in the rat hippocampal homogenates of scopolamine-treated animals as compared with control, as a consequence of impaired antioxidant enzymes activities. Additionally, in scopolamine-treated rats 6HLN significantly improved memory formation and decreased oxidative stress, suggesting memory-enhancing and antioxidant effects. Therefore, our results suggest that administration of 6HLN ameliorates scopolamine-induced spatial memory impairment by attenuation of the oxidative stress in the rat hippocampus.