INCREASED MITOCHONDRIAL SUPEROXIDE-DISMUTASE ACTIVITY IN PARKINSONS-DISEASE BUT NOT AMYOTROPHIC-LATERAL-SCLEROSIS MOTOR CORTEX

Oxidative stress may contribute to the neurodegenerative process in am yotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). Motor cortex in PD is not affected and its inclusion in studies of free radi cal involvement in ALS pathogenesis could help elucidate whether oxida tive stress is disease specific or a more widespread phenomenon presen t in the neurodegeneration. We have measured cytosolic and mitochondri al isoforms of superoxide dismutase (SOD), antioxidant enzymes involve d in primary defence against free radical damage, in motor cortex of s ix patients with sporadic form of ALS (SALS), eight with PD and eight normal control subjects. We have found no difference in the activities of cytosolic and mitochondrial SOD between SALS and control motor cor tex. Mitochondrial SOD activity in PD motor cortex was, however, signi ficantly higher than in SALS and control motor cortex whereas activity of cytosolic SOD was lower than in two other groups although the diff erences were not statistically significant. Our findings indicate the presence of an altered antioxidant defence system in PD but not ALS up per motor neurons, suggesting that oxidative stress may be a widesprea d phenomenon in PD. (C) 1997 Elsevier Science Ireland Ltd.