Comparative immunohistochemical study on synaptophysin expression in the anterior horn of post-poliomyelitis and sporadic amyotrophic lateral sclerosis

This report concerns a comparative study of alterations of anterior horn presynaptic terminals in postpoliomyelitis and sporadic amyotrophic lateral sclerosis (S-ALS). Synaptophysin (SP) served as a marker for presynaptic terminals; immunohistochemical techniques were used throughout. Spinal cords from six individuals without neurological disease served as controls. Localized and well-delineated anterior horn neuropil areas with decreased SP immunoreactivity were observed in the five cases of postpoliomyelitis studied. These areas had few remaining neurons but had pronounced reactive gliosis which corresponded to those areas in which typical poliomyelitis lesions were present. Normal neuronal SP expression was preserved in the adjacent, non-affected areas. However, a small region with increased SP levels was observed in one case. By comparison, the decrease in anterior horn SP immunoreactivity was diffuse in the four S-ALS patients studied. The present data suggest that presynaptic terminals ending at the somata and processes of affected anterior horn neurons located in the area of the acute infection are degenerate in post-poliomyelitis. By contrast, in S-ALS the terminals ending at distal dendrite portions tend to be severely degenerate, while those terminating at the proximal portions of the neuron are relatively well preserved. Our results thus provide additional evidence that the pathogenesis of the post-poliomyelitis state differs from that of ALS.