Normal pituitary response to metyrapone in the morning in depressed patients: implications for circadian regulation of corticotropin-releasing hormone secretion.

Excess secretion of cortisol in depressed patients has been documented by a number of investigators, which is presumed secondary to increased corticotropin (ACTH) and ACTH-releasing hormone (CRH) secretion. To unmask the proposed increased central (CRH) drive, we administered metyrapone in the AM to 13 depressed and 13 age- and sex-matched normal control subjects. Metyrapone administration resulted in a prompt decrease in plasma cortisol and in an increase in 11-deoxycortisol, the inactive precursor, in all subjects. Both depressed patients and normal control subjects demonstrated clear increases in ACTH and beta-lipotropin/beta-endorphin production. There were no significant differences between patients and controls in any hormonal measures following metyrapone administration. These data suggest that: 1) in the absence of negative feedback (cortisol blockade), mildly to moderately depressed outpatients do not manifest increased central drive in the morning; and 2) the secretory capacity of the corticotropes do not differ between such depressed patients and controls.