Delta-sleep-inducing peptide does not affect CRH and meal-induced ACTH and cortisol secretion.

Besides sleep-promoting properties, delta-sleep-inducing peptide (DSIP) has been reported to act as a corticotropin-releasing inhibiting factor in vitro and in vivo. We examined, first, the influence of DSIP on ACTH and cortisol release following stimulation with human corticotropin-releasing hormone (h-CRH; 1.0 microgram/kg body weight, and 0.5 microgram/kg body weight, respectively) in healthy young men (n = 5 in each condition). DSIP (total doses of 3 and 4 mg, respectively, vs. placebo) was infused intravenously between 30 min prior to and 90 min after CRH injections. Responses of ACTH and cortisol were almost identical during and after infusion of DSIP and placebo. In a second experiment, the influence of DSIP (4 mg, also administered as intravenous infusion) on meal-related ACTH and cortisol secretion was studied in another 10 men. Meal-related midday surge of ACTH and cortisol was also not affected by DSIP. Our data do not support an inhibitory role of DSIP on ACTH and cortisol secretion in man.