Effect of 6-hydroxydopamine and 5,7-dihydroxytryptamine on tissue uptake and cell nuclear retention of corticosterone in the rat hypothalamus.

Previous studies have shown that norepinephrine and serotonin can modulate the glucocorticoid (GC) binding capacity in the hippocampus. The aim of the present study was to evaluate the role of these neurotransmitters in regulating GC receptors in the hypothalamus. Injection of the neurotoxin 6-hydroxydopamine (6-OHDA) into the ventral noradrenergic bundle (VNAB) and 5,7-dihydroxytryptamine (5,7-DHT) into the raphe nuclei caused a marked depletion in norepinephrine and serotonin, respectively, in the paraventricular nucleus (PVN) and mediobasal hypothalamus (MBH). The injection of these neurotoxins did not change the basal levels of ACTH and corticosterone. Injection of 6-OHDA into the VNAB caused a significant reduction in the cell nuclear binding of corticosterone in the PVN but not in the MBH. Conversely, injection of 5,7-DHT into the raphe nuclei caused a significant reduction in cell nuclear binding of corticosterone in the MBH but did not affect binding in the PVN. These results demonstrate that at least part of the nuclear corticosteroid receptors in the PVN and MBH are differentially regulated by the noradrenergic and serotonergic systems.