THE EFFECTS OF CHRONIC EXPOSURE OF MANGANESE ON ANTIOXIDANT ENZYMES IN DIFFERENT REGIONS OF RAT-BRAIN

The present study was designed to investigate if chronic exposure to m anganese (Mn) produces an effect on antioxidant enzymes such as supero xide dismutase (SOD), glutathione peroxidase (GPx) activities and redu ced glutathione (GSH) content in different regions of rat brain. Adult male Sprague-Dawley (CD) rats were dosed with 0, 2.5 or 5.0 mg MnCl2/ kg, for 3 months (5 days/week). The activity of total superoxide dismu tase did not vary significantly in any region of the brain with either 2.5 or 5.0 mg MnCl2/kg. A significant increase of Mn-superoxide dismu tase (Mn-SOD) activity was attained in hippocampus, cerebellum and bra in stem. The Cu,Zn-superoxide dismutase activity was reduced in all re gions of the brain, however, reduction was not statistically significa nt. No significant effect of Mn on glutathione peroxidase activity was observed in any region of the brain. Glutathione content was signific antly reduced in cerebellum, whereas, no change was observed in other brain regions. The results show that chronic exposure to manganese sig nificantly increased the Mn-superoxide dismutase activity in selected brain regions. Therefore, increased Mn-SOD may enhance the antioxidant ability of the brain to reduce oxidative stress. (C) 1997 John Wiley & Sons, Ltd.