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Melatonin has recently been suggested as an antioxidant that may protect neurons from oxidative stress. Acute ethanol administration produces both lipid peroxidation as an indicator of oxidative stress in the brain and impairs water-maze performance in spatial learning and memory tasks. The present study investigated the effect of melatonin against ethanol-induced oxidative stress and spatial memory impairment. The Morris water maze was used to evaluate the cognitive functions of rats. Thiobarbituric acid reactive substances (TBARS), which are the indicators of lipid peroxidation, and the activities of antioxidative enzymes (glutathione peroxidase and superoxide dismutase) were measured in the rat hippocampus and prefrontal cortex which form interconnected neural circuits for spatial memory. Acute administration of ethanol significantly increased TBARS levels in the hippocampus. Combined melatonin-ethanol treatment caused a significant increase in glutathione peroxidase activities and a significant decrease of TBARS in the rat hippocampus. In the prefrontal cortex, there was only a significant decrease of TBARS levels in the combined melatonin-ethanol receiving group as compared to the ethanol-treated group. Melatonin did not affect the impairment of spatial memory due to acute ethanol exposure, but melatonin alone had a positive effect on water maze performances. Our study demonstrated that melatonin decreased ethanol-induced lipid peroxidation and increased glutathione peroxidase activity in the rat hippocampus.

Cerebral ischemia leads to neuronal damage in the hippocampus and cognitive decline. Reactive oxygen species play an important role in the neuronal loss after cerebral ischemia and reperfusion injury. Deprenyl, an irreversible monoamine-oxidase B inhibitor, has antioxidant and neuroprotective effects against reactive oxygen species. In the present study, the effect of deprenyl on spatial memory impairment, oxidative stress and apoptotic neuronal cell death following transient cerebral ischemia in rats was investigated. Transient ischemia was induced by occlusion of left common carotid artery of rats for 30 min and reperfusion for 24 h or 1 week. Rats received intraperitoneal injection of 1 mg/kg deprenyl (n = 24) or equal volume of saline (n = 24) for 14 days before the experiment. Deprenyl treatment attenuated spatial memory deficits following ischemia-reperfusion as measured by the Morris water maze task. Deprenyl treatment elicited a significant decrease in lipid peroxidation and increase in superoxide dismutase activities in ischemic rat brains. The number of TUNEL-positive cells decreased significantly in deprenyl-treated group when compared with the control group. The results show that deprenyl reduces the ischemia-induced oxidative stress and thus prevents spatial memory deficits and apoptotic neuronal cell death when it is administered before ischemia-reperfusion. © 2008 by The Chinese Physiological Society.

To investigate the effect of blood perfusion difference on oxidant status, mice were trained by a 7-week running program. Two days after the last training session, mice were exercised for 60 minutes at the same training intensity. Changes in the concentration of thiobarbituric acid reactive substance (TBARS), as an index of lipid peroxidation, in intestine, kidney and muscle, were studied in trained mice immediately (0 h), 3 h and 24 h after the running exercise and in unexercised control group. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and xanthine oxidase (XO) were determined in these tissues. Tissue SOD activities were unaffected by the exercise. Muscle GPx activity increased after exercise (0 h and 3 h group, P0.01) and returned to control levels at 24 h, but there was not any significant difference in intestinal and renal tissues. Renal tissue XO activity could not be determined. There was not any significant difference among groups in intestinal tissue XO activity. The activity of XO was decreased only in skeletal muscle at 0 h (P0.05). TBARS levels of exercised groups were higher than control in muscle (P0.01). Intestinal TBARS levels decreased at 0 h (P0.05), than reached to control level. Renal TBARS levels of 0 h and 24 h group was higher than control (P0.01, P0.01 respectively). The results show that a long distance running exercise may cause lipid peroxidation damage in skeletal muscle and kidney.

In a previous study we demonstrated that repeated maternal separation impaired spatial memory performance in both male and female adolescent rats. The mechanisms of these cognitive alterations are unknown. In the present study, we examined the effects of repeated maternal separation on oxidative stress in the hippocampus, prefrontal cortex and striatum regions of the brain of the adolescent male and female rats. The results showed that repeated maternal separation increased antioxidant enzyme activities and lipid peroxidation in adolescent male rat brains; however, maternal separation did not effects antioxidant enzyme activities and lipid peroxidation in adolescent female rat brains. These results suggest that oxidative stress caused damage in repeated maternal separated adolescent male rat brains, also a strong role of gender in the response of adolescent subjects to maternal separation.