INCREASED NEURITE OUTGROWTH OF CULTURED RAT DORSAL-ROOT GANGLION-CELLS FOLLOWING TRANSECTION OR INHIBITION OF AXONAL-TRANSPORT OF THE SCIATIC-NERVE

Dissociated dorsal root ganglion cells (DRGs), taken from rats 2 weeks after sciatic nerve transection, have an increase in the per centage of cells with neurites compared to DRGs taken from normal animals. Thi s study examines the possible factors that may contribute to the nerve injury-induced increase in neuritogenesis. Topical application of the local anaesthetic, bupivicaine, either to the nerve trunk prior to tr ansection or to the proximal nerve stump for 2 weeks had no effect on the increased neurite outgrowth induced by nerve transection. Neurite outgrowth was also not influenced by administration of either nerve gr owth factor (NGF) via the femoral artery into normal rats or anti-NGF antiserum to the proximal nerve stump. Inhibition of axonal transport by topical application of vinblastine, however, induced a significant increase in neurite outgrowth compared to untreated controls. In addit ion, vinblastine-treated animals also develop hyperalgesia to mechanic al stimulation and transganglionic labelling of sensory neurons with c holeragenoid-horseradish peroxidase shows that the area of termination of myelinated sensory neurons in the spinal cord expands into lamina II. The results suggest that nerve injury-induced increase in neurite outgrowth is not dependent on NGF nor nerve impulses generated at the site of injury and supports the view that the absence of an inhibitory factor(s), that in normal animals may regulate neuronal outgrowth.