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The Inhibitory Effect of Alprazolam, a Benzodiazepine, Overrides the Stimulatory Effect of Metyrapone-Induced Lack of Negative Cortisol Feedback on Corticotroph Secretion in Humans¹

Division of Endocrinology, Department of Internal Medicine, University of Turin, Turin, Italy

Address all correspondence and requests for reprints to: E. Ghigo, M.D., Divisione di Endocrinologia, Ospedale Molinette, C. so Dogliotti 14, 10126 Torino, Italy. E-mail: camanni{at}pianeta.net

Alprazolam (ALP), a benzodiazepine that activates -aminobutyric acid-ergic receptors, inhibits the activity of hypothalamo-pituitary-adrenal (HPA) axis, probably via inhibition of hypothalamic CRH and/or arginine vasopressin release. To further clarify the effects of ALP on the HPA axis in humans, in six normal young women (26–34 yr old) we studied the effects of 0.02 mg/kg ALP (administered orally at 0700 h) or placebo on ACTH, cortisol (F), and 11-deoxycortisol (S) levels assayed after placebo or metyrapone (MET; 0.04 g/kg administered orally at 2300 h the night before). After placebo administration, ACTH, F, and S levels showed a progressive decrease from 0700–1200 h (P < 0.03). At 0700 h, ACTH, F, and S levels before ALP overlapped with those after placebo. At 1200 h, ACTH, F, and S levels after ALP were lower than those after placebo (P < 0.03). MET pretreatment strongly increased ACTH (P < 0.03) and S (P < 0.02) while clearly inhibiting F (P < 0.03) levels at 0700 h. After MET, ACTH levels did not show any decrease up to 1200 h; similarly, S levels persisted similar up to 1200 h, whereas F levels at 1200 h were significantly increased (P < 0.03). At 0700 h, MET-induced ACTH and F levels before ALP overlapped with those after MET alone. The MET-induced ACTH levels at 1200 h were markedly inhibited by ALP (P < 0.05). At 1200 h after MET and ALP, a clear reduction of S levels (P < 0.02) and an insignificant F reduction were also found. In conclusion, our present data show that ALP inhibits basal and, much more, metyrapone-induced corticotroph secretion. These findings indicate that the inhibitory effect of central -aminobutyric acid-ergic activation by ALP overrides the stimulatory effect of the MET-induced lack of negative F feedback on corticotroph secretion. These results also point toward potential contraindication of ALP administration in patients with suspected hypoadrenalism.

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				S. Grottoli, R. Giordano, B. Maccagno, M. Pellegrino, E. Ghigo, and E. Arvat The Stimulatory Effect of Canrenoate, a Mineralocorticoid Antagonist, on the Activity of the Hypothalamus-Pituitary-Adrenal Axis Is Abolished by Alprazolam, a Benzodiazepine, in Humans J. Clin. Endocrinol. Metab., October 1, 2002; 87(10): 4616 - 4620. [Abstract] [Full Text] [PDF]