The effect of acute or/and chronic stress on the MnSOD protein expression in rat prefrontal cortex and hippocampus.

Manganese superoxide dismutase (MnSOD) is the major antioxidant in mitochondria that protect brain from neuroendocrine stress. Although MnSOD is localized in the mitochondria, the immediate subcellular distribution of MnSOD protein level in the prefrontal cortex and hippocampus of Wistar male rats exposed to acute stressors immobilization or cold, chronic stress isolation or their combinations (acute/chronic) have not been studied. Western immunoblotting revealed that acute immobilization stress resulted in an increase in mitochondrial MnSOD protein level, whereas chronic isolation compromises MnSOD protein level. Chronically stressed animals exposed to novel acute stressors showed a significant decrease in mitochondrial MnSOD protein level and reciprocal increase in this protein in the cytosolic fraction. At the same time, a significant increase in serum corticosterone level was observed after acute stressors, whereas chronic isolation led to negligable changes and caused a reduced responsiveness to a novel acute stressors. Presence of cytochrome c in mitochondrial and cytosolic fraction of both brain structures was also confirmed. Results suggest that chronic stress isolation results in mitochondrial dysfunction and MnSOD release into the cytosol.