Cytosol Glucocorticoid Binding in Monoaminergic Cell Groups

Abstract

The following nuclei containing monoaminergic neurons were punched out from frozen sections of rat brain: locus coeruleus, dorsal raphe nucleus, medial raphe nucleus, and substantia nigra zona compacta. Cytosol preparations from the dissected tissues were examined for ³H-corticosterone binding. Only the locus coeruleus showed a substantial level of ³H-corticosterone binding. No binding capacity was found in cytosols from the raphe nuclei and the substantia nigra. The cytosol steroid binding of the locus coeruleus was determined developmentally. The binding capacity was found to remain virtually unchanged from postnatal day 5 (the earliest period examined) to adulthood. It is possible that a cytoplasmic glucocorticoid receptor may be present in the noradrenergic neurons of the locus coeruleus. Since ³H-corticosterone binding is absent in the raphe nuclei and substantia nigra, biochemical mechanisms; involving a glucocorticoid-receptor interaction directly in these serotonergic and dopaminergic neurons may be ruled out.