The effect of naloxone on ATCH and beta-endorphin in patients with Cushing's disease.

Endogenous opiates may be important in the control of ACTH secretion in men. The effect of opiate receptor blockade by naloxone on ACTH, beta-endorphin-like substance and cortisol release was studied in healthy women and in 9 patients with Cushing's disease. In the healthy subjects, ACTH, beta-endorphin and cortisol levels were increased in response to naloxone. However, in 3 our of the 9 patients with Cushing's disease, a paradoxical decrease in serum ACTH, cortisol and beta-endorphin concentrations was observed after naloxone administration. In the patients with a paradoxical response to naloxone, transsphenoidal microadenomectomy was ineffective.