PRESENCE OF CU ZN SUPEROXIDE-DISMUTASE (SOD) IMMUNOREACTIVITY IN NEURONAL HYALINE INCLUSIONS IN SPINAL-CORDS FROM MICE CARRYING A TRANSGENEFOR GLY93ALA MUTANT HUMAN CU/ZN SOD/

This investigation deals with the immunocytochemical localization of C u/Zn superoxide dismutase (SOD) in the spinal cord neurons of transgen ic mice that overexpress Gly93Ala mutant human Cu/Zn SOD and demonstra te clinicopathological features similar to human amyotrophic lateral s clerosis (ALS) with Cu/Zn SOD mutation. Al low magnification of light microscopy; the gray and white matter of the spinal cord of Gly93Ala m ice showed more intense Cu/Zn SOD immunoreactivity than that of contro l mice. Ar higher magnification, the cytoplasm of control mice neurons displayed a distinct staining for Cu/Zn SOD, whereas the surrounding neuropil was only weakly stained, In contrast, the intensity of Cu/Zn SOD immunoreactivity in the cytoplasm of the majority of Gly93Ala mice neurons was similar to that in the neuropil. Almost all neuronal hyal ine inclusions (NHIs) of Gly93Ala mice were positively immunostained b y antibodies to Cu/Zn SOD, ubiquitin and phosphorylated neurofilament protein (NFP), the intensities of which were much higher in the NHIs t han in the surrounding cytoplasm. In control mice, significant Cu/Zn S OD precipitation was not observed to be limited to any particular regi on of the neuronal cytoplasm. Intracytoplasmic vacuoles in the neurona l soma and processes of Gly93Ala mice were not stained by any of these antibodies. These results indicate that Cu/Zn SOD colocalizes with ub iquitin and phosphorylated NFP in NHIs of mice expressing mutant Cu/Zn SOD, similar findings have been shown for Lewy body-like inclusions o f familial ALS patients with Cu/Zn SOD mutation. Moreover, our results point to the possibility that Cu/Zn SOD mutation may have a role in t he abnormal Cu/Zn SOD accumulation in the NHIs, in association with mo tor neuron degeneration.