Magnitude of GAP-43 induction following peripheral axotomy of adult rat dorsal root ganglion neurons is independent of lesion distance.

Regenerative axon growth in peripheral neurons is accompanied by increased expression of the growth-associated protein GAP-43. We examined the increase of GAP-43 immunoreactivity in DRG neurons following lesions at different distances along the sciatic nerve, using immunocytochemistry. To control for the variable involvement of DRG axons following injury at different sites, injured neurons were identified by retrograde labeling with Fluoro-Gold. GAP-43 labeling was similar for proximal, distal, and far-distal injuries when only injured neurons are considered. Our results stand in contrast to studies which show that GAP-43 upregulation in neurons of the central nervous system occurs only when lesions are made close to the cell body. This suggests that the mechanisms which control GAP-43 expression following injury differ between central and peripheral neurons.