Increased expression of growth-associated protein 43 on the surface of theanterior horn cells in amyotrophic lateral sclerosis

This study examined axonal terminal alterations in the anterior horn of amy otrophic lateral sclerosis (ALS) patients. An antibody against growth-assoc iated protein 43 (GAP43), a phosphoprotein which is expressed in elongating terminals of neurites, was employed for immunohistochemical staining. Lumb ar spinal cords taken at autopsy from five ALS patients and from six contro l adults were examined. In control patients, there were numerous GAP43-posi tive granules diffusely dispersed throughout the anterior horn neuropil, an d individual large anterior horn cells (AHCs) showed numerous tiny immunore active granules and small dots on the surface. A small number of AHCs showe d dense accumulation of GAP43 immunoreactivity on the surface of the cell b ody and proximal processes. In all ALS patients, similar accumulation of GA P43 immunoreactivity was seen on the surface of a large number of remaining AHCs. Statistical analysis revealed a significant increase in number of AH Cs with such accumulation in ALS patients. These results suggest that durin g the ALS disease process there may be plastic alterations or a compensator y mechanism of the axonal terminals located on the surface of some AHCs for ongoing anterior horn presynaptic terminal degeneration.