Increased Cu/Zn superoxide dismutase-like immunoreactivity in the swollen axons of rats intoxicated chronically with beta,beta'-iminodipropionitrile.

Demonstration of a genetic linkage between the Cu/Zn superoxide dismutase (SOD1) gene and familial amyotrophic lateral sclerosis (ALS) has aroused interest in the role of SOD1 in spinal motoneuronal death. We used chronically beta,beta'-iminodipropionitrile (IDPN)-intoxicated rats as a model of ALS and investigated SOD1 changes in the spinal cord by immunocytochemical and in situ hybridization techniques. Compared with control rats, SOD1-like immunoreactivity (SOD1-IR) increased in swollen axons of the proximal spinal roots, but not in motoneuronal and dorsal root ganglion neuronal cell bodies where SOD1 gene transcription did not increase. The present data indicate that treatment with IDPN induces accumulation of SOD1 in the swollen axons by blocking slow axonal flow, suggesting the possibility that increased SOD1-IR in ALS is induced by axonal flow blockade.