The effect of spinal cord transection on the development of cholinergic and adrenergic sympathetic neurons

Abstract

Summary The role of central pathways in the maturation of cholinergic and adrenergic sympathetic neurons was studied in the neonatal rat. The ontogeny of the sixth lumbar (L-6) ganglion was examined after midthoracic spinal transection in 0–11-day-old animals. Initial experiments defined the normal development of presynaptic choline acetyltransferase (ChAc) and postsynaptic tyrosine hydroxylase (T-OH) activities in L-6 ganglia. The pattern of maturation was similar to that previously described for the superior cervical ganglion, but was delayed, suggesting a rostrocaudal gradient of sympathetic development. Spinal transection prevented the normal development of presynaptic terminals and postsynaptic neurons in the L-6 ganglion. ChAc activity failed to increase during the first postoperative week, and at 2 months of age was less than 50% of normal. Postsynaptic T-OH and DOPA decarboxylase activities also failed to increase normally after spinal transection. These abnormalities were not attributable to direct damage to presynaptic intermediolateral column neurons in the spinal cord, since histological examination did not reveal neuronal dropout, neuronophagia or gliosis. These observations suggest that spinal pathways regulate the maturation of proximate presynaptic cholinergic neurons and second-order postsynaptic adrenergic neurons in the autonomic system.