Functions and dysfunctions of receptors for adrenal corticoids in the central nervous system

Glucocorticoids (GC) have several known effects on the function of the nervous system, and GC receptors have been identified in regions responding to hormonal action. In the spinal cord, GC receptors have been characterized in vitro, which share several biochemical properties in common with receptors in better studied areas such as the hippocampus. Moreover, enzymes which are induced by GC in the hippocampus, such as glycerolphosphate dehydrogenase and ornithine decarboxylase, are also under specific GC control in the spinal cord. Yet GC receptors in the latter tissue divert from those in hippocampus during some in vivo as well as in vitro studies. In vivo, uptake of [3H]corticosterone by purified cell nuclei was 5-8-fold higher in the hippocampus as compared to the cord. In vitro, a higher percentage of GC receptors previously transformed by heating, showed affinity towards DNA-cellulose in the spinal cord than in the hippocampus. The enzyme RNAse A effectively increased receptor binding to DNA-cellulose in hippocampus, whereas the cord was insensitive to its action. These results suggest that there is a "receptor dysfunction" in the spinal cord, the significance of which is poorly understood in terms of the accepted model of steroid hormone action.