Synthesis and transport of GAP-43 in entorhinal cortex neurons and perforant pathway during lesion-induced sprouting and reactive synaptogenesis.

Metabolic labeling and quantitative 2D gel autoradiography were used to assess changes in the synthesis and transport of GAP-43 in entorhinal cortex (EC) neurons and perforant pathway during lesion-induced sprouting and reactive synaptogenesis. In normal adult rats, there is a high constitutive level of GAP-43 synthesis and transport in EC neurons projecting to the hippocampus. Following unilateral EC lesions, there is a 2-fold (100%) increase in the transport of newly synthesized GAP-43 to the contralateral or 'sprouting' hippocampus. The timing of this upregulation (between 6 and 15 days) suggests that changes in GAP-43 expression occur in response to the growth of presynaptic terminals during sprouting.