Decrease in Cu/Zn- and Mn-superoxide dismutase activities in brain and spinal cord of patients with amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a degenerative disorder of motor neurons in the central nervous system (CNS). Mutation of the Cu/Zn-superoxide dismutase (SOD) gene on chromosome 21 has been found in some families with autosomal dominant familial ALS (FALS). We sought to determine whether there may be differences in the distribution and activity of SOD in the CNS of patients with sporadic ALS, and of control patients without neurological disorders. The frontal cortex, cerebellum, and spinal cord were obtained at autopsy on 5 patients with ALS and from 10 controls. Immunohistochemically, in the controls, the cytosols of the large pyramidal neurons of the cerebral cortex, anterior and posterior horn cells, and neurons of the nucleus thoracicus of spinal cord were stained homogeneously with anti-human Cu/Zn-SOD antibody, and in a granular manner with anti-human Mn-SOD antibody. Pia mater and epithelial cells of choroid plexus also stained well. Conversely, in the CNS of the ALS patients, most neurons were stained faintly, or not at all with both anti-Cu/Zn- and Mn-SOD antibodies, whereas the pia mater and the epithelial cells of choroid plexus stained intensely. There was no difference in total SOD activity in the entire CNS between ALS patients and controls, as determined by enzyme assay. Results suggest that, in cases of sporadic ALS, the activities of Cu/Zn- and Mn-SOD are decreased and superoxide produced within the neurons accumulates because of an insufficient elimination, leading to the development or acceleration of cell damage, ultimately producing neuronal degeneration and necrosis.