ELECTROPHYSIOLOGICAL STUDIES ON RAT DORSAL-ROOT GANGLION NEURONS AFTER PERIPHERAL AXOTOMY - CHANGES IN RESPONSES TO NEUROPEPTIDES

The effect of three peptides, galanin, sulfated cholecystokinin octape ptide, and neurotensin (NT), was studied on acutely extirpated rat dor sal root ganglia (DRGs) in vitro with intracellular recording techniqu es. Both normal and peripherally axotomized DRGs were analyzed, and re cordings were made from C-type (small) and A-type (large) neurons. Gal anin and sulfated cholecystokinin octapeptide, with one exception, had no effect on normal C- and A-type neurons but caused an inward curren t in both types of neurons after sciatic nerve cut. In normal rats, NT caused an outward current in C-type neurons and an inward current in A-type neurons. After sciatic nerve cut, NT only caused an inward curr ent in both C- and A-type neurons. These results suggest that (i) norm al DRG neurons express receptors on their soma for some but not all pe ptides studied, (ii) C- and A-type neurons can have different types of receptors, and (iii) peripheral nerve injury can change the receptor phenotype of both C- and A-type neurons and may have differential effe cts on these neuron types.