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- Title
Acute Inhibition of Pituitary LH Release in the Male Rat by the Glucocorticoid Agonist Decadron Phosphate.
- Authors
Briski, Karen P.; Sylvester, Paul W.
- Abstract
The present study was carried out to investigate the effects of acute administration of the soluble glucocorticoid receptor agonist, decadron phosphate (DEC, dexamethasone sodium phosphate), on pituitary luteinizing hormone (LH) release in intact adult male rats. DEC was administered intravenously to individual groups of animals at a dose of either 0.05 or 0.5 mg DEC/kg, and the magnitude and time course of drug-induced alterations in plasma LH concentrations were evaluated. DEC was observed to elicit a dose-proportionate decrease in plasma LH within hours after systemic injection. Both doses of DEC significantly reduced the magnitude of exogenous LH-releasing hormone (RH; 10 ng/100 g b.w.)-induced increases in plasma LH at time points coincident with drug-induced decreases in basal LH release. During in vitro perifusion of isolated anterior pituitary tissue fragments, the administration of DEC, via the perifusate, at a concentration of 1.0 μg/ml had no impact upon basal LH release, but did effectively diminish LHRH-stimulated hormone release from perifused tissues. Intracerebroventricular injection of DEC also resulted in a decline in circulating LH. While intracerebroventricular (ICV) administration of 10 ng of DEC had no impact upon circulating LH, higher doses of 100 ng and 1.0 μg significantly depressed circulating LH levels in a dose-related manner. Both of these ICV doses were also found to diminish pituitary responsiveness to LHRH. Lastly, DEC was intravenously administered at a dose of 0.5 mg/kg to groups of orchidectomized and orchidectomized, testosterone (T)-treated male rats. The glucocorticoid receptor agonist had no effect upon circulating LH levels in orchidectomized rats treated with vehicle, but did diminish hormone release in animals injected with T (2 mg/kg b.w.) 24 h before DEC administration. These results demonstrate the acute inhibitory impact of the soluble glucocorticoid receptor agonist DEC on pituitary LH release in intact male rats. The present findings not only support previous reports that glucocorticoid receptor ligands may act directly at the level of the anterior pituitary to suppress LH release, but also provide new evidence that glucocorticoid receptors present within the central nervous system may mediate an inhibitory influence on the neuroendocrine regulation of the LH release. The current results also indicate that the sensitivity of the hypothalamic-pituitary LH neuroendocrine axis to the inhibitory action of glucocorticoids may be diminished in the absence of T. Copyright © 1991 S. Karger AG, Basel
- Publication
Neuroendocrinology, 1991, Vol 54, Issue 4, p313
- ISSN
0028-3835
- Publication type
Article
- DOI
10.1159/000125908