Induction of spinal NADPH-diaphorase by nerve injury is attenuated by adrenal medullary transplants.

Persistent sensory abnormalities consequent to injury may involve prolonged neuroplastic changes in the spinal cord similar to those in long-term potentiation. Molecular markers, like the putative nitric oxide synthase, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d), can be useful indicators of increased neuronal activity. Peripheral nerve injury markedly increased NADPH-d-labeling in sensory regions of the spinal cord, paralleling induction of abnormal pain (hyperalgesia). Both NADPH-d activation and hyperalgesia were reversed by transplantation of opioid/catecholamine-producing adrenal medullary tissue into the spinal subarachnoid space. These results suggest that adrenal medullary transplants can attenuate abnormal neuronal activity consequent to injury.