Target neurons for [3H]corticosterone in the rat spinal cord.

Rats were injected with [3H]corticosterone and their spinal cords processed for autoradiography. Nuclear concentration of the tritiated steroid was observed in motor neurons in cervical, thoracic, lumbar, and sacral regions. Nuclear concentrations of [3H]corticosterone was also observed in certain neurons of laminae VII and III in all levels of the spinal cord. Injection of unlabeled corticosterone 5 min before the [3H]corticosterone injection abolished the nuclear concentration of the adrenal steroid. These results provide the morphological basis for a direct genomic action of corticosterone in spinal motor neurons and in neurons of laminae III and VII.