EFFECT OF SLEEP-DEPRIVATION ON NEUROENDOCRINE RESPONSE TO A SEROTONERGIC PROBE IN HEALTHY MALE-SUBJECTS

Neuroendocrine responses to stimulation with a selective serotonin reu ptake inhibitor (citalopram) were measured to investigate the effects of all-night sleep deprivation on serotonergic function in healthy mal e subjects (n=7). We studied citalopram-stimulated prolactin and corti sol plasma concentrations in a placebo-controlled cross-over protocol following sleep and sleep deprivation. Citalopram infusion (20 mg i.v. at 14:20-14: 50 h) after a night of undisturbed sleep prompted robust increases in both plasma prolactin and cortisol concentrations. Follo wing a night of sleep deprivation, by contrast, the citalopram-induced prolactin response was blunted, but the cortisol response was not sig nificantly altered. This differential response pattern relates to the distinct pathways through which serotonin may activate the corticotrop hic and the lactotrophic systems. While an unchanged cortisol response does not indicate (but also does not refute the possibility of) an al tered serotonergic responsivity following sleep deprivation, the suppr essed prolactin response could reflect a downregulation of 5-HT1A or ( 2) receptors. An alternative, not mutually exclusive, explanation poin ts to the possibility that sleep deprivation activates the tuburoinfun dibular dopaminergic system, the final inhibitory pathway of prolactin regulation. (C) 1997 Elsevier Science Ltd.