Adrenal medullary transplants attenuate sensorimotor dysfunction in rats with peripheral neuropathy.

Previous work in our laboratory has demonstrated that adrenal medullary transplants into the spinal subarachnoid space can alleviate neuropathic pain behaviors. The purpose of this study was to test the possibility that motor, as well as, sensory dysfunction is reduced by adrenal medullary transplants. Peripheral neuropathy was induced by a chronic constriction injury (CCI) of the sciatic nerve of rats. In addition to exaggerated responses to noxious and innocuous stimuli characteristic of peripheral nerve injury, severe impairment of hindpaw placing and grasping reflexes following CCI was observed. Two weeks following CCI, either adrenal medullary or control striated muscle tissue was implanted into the spinal subarachnoid space. Adrenal medullary, but not control transplants, produced significant restoration of hindlimb reflex function in animals with peripheral nerve injury. This was reversed by pretreatment with the alpha-adrenergic antagonist phentolamine, but not the opiate antagonist naloxone, suggesting a role for catecholamines secreted by the implanted cells in reflex recovery. Adrenal medullary transplants also attenuated hyperalgesia and allodynia resulting from nerve injury. These results indicate that adrenal medullary transplants can alleviate sensorimotor dysfunction consequent to peripheral nerve injury.