Intraspinal cellular responses after spinal cord transection in rats: neuronal expression of growth-associated protein (GAP-43).

The methods of non-radioisotopic in situ hybridization and immunocytochemistry were used to visualize sites of GAP-43 expression after a mid-thoracic spinal cord transection in adult rats. Neurons which expressed moderate to high levels of GAP-43 mRNA and showed strong GAP-43-like immunoreactivity were located immediately above the lesion site as well as at greater distances from the lesion site in the lower cervical and mid-lumbar spinal cord. The results of this study suggest a widespread occurrence of lesion-induced neuroplastic changes and may indicate that the increase in GAP-43 expression can be caused by axotomy, deafferentation and increased compensatory motor activity in the spinal cord of paraplegic rats.