Reduction of activities of superoxide dismutase but not of glutathione peroxidase in rat brain regions following decapitation ischemia.

Effects of complete ischemia on levels of antioxidative enzymes including copper-zinc (CuZn) superoxide dismutase (SOD), manganese (Mn)-SOD, and glutathione peroxidase (GSH-Px) were studied in rat brain regions at 30 and 60 min following decapitation. CuZn-SOD activities were significantly decreased in cerebral cortex and hippocampus at both time points whereas the enzyme activities were decreased at 60 min in cerebellum and caudate areas. The reduction of Mn-SOD activities followed the same pattern of CuZn-SOD in various brain regions. However, GSH-Px activities in these brain regions were not affected by decapitation ischemia. These data suggest that the reduction of CuZn-SOD and Mn-SOD activities during ischemia, in conjunction with the significant decrease in the contents of alpha-tocopherol and other endogenous antioxidants, may compromise the brain's ability to defend against the toxic effects of superoxide radicals formed by ischemia and by subsequent reoxygenation.