Low-dose citalopram as a 5-HT neuroendocrine probe.
BACKGROUND
Intravenous administration of the selective serotonin re-uptake inhibitor, citalopram (20 mg), is known to increase plasma prolactin (PRL) and cortisol in human subjects. This suggests that citalopram may be a useful tool to probe brain serotonin function.


OBJECTIVE
To find out whether lower doses of intravenous citalopram would be sufficient to increase plasma prolactin and cortisol.


METHODS
Eleven subjects were tested on three occasions in a double-blind, cross-over design receiving: (a) placebo, (b) citalopram 5 mg and (c) citalopram 10 mg infused intravenously over a 30-min period. A further six subjects received intravenous citalopram (10 mg) on two occasions receiving in addition the 5-HT2A2C receptor antagonist, cyproheptadine (4 mg orally) or placebo, 6 h before each infusion in a double-blind, randomised, cross-over design. Plasma PRL and cortisol levels were measured before and for 150 min after the infusion.


RESULTS
Citalopram increased plasma PRL and cortisol in a dose-related manner. Cyproheptadine lowered baseline PRL and cortisol but did not attenuate the endocrine responses to citalopram. Citalopram infusions were well-tolerated.


CONCLUSIONS
Low-dose citalopram has potential utility as a neuroendocrine challenge test. The endocrine responses to citalopram are probably not mediated predominantly by 5-HT2A/2C receptors.
Attenburrow
M J
MJ
University Department of Psychiatry, Warneford Hospital, Oxford, UK.
Mitter
P R
PR
Whale
R
R
Terao
T
T
Cowen
P J
PJ
D000328:Adult; D015283:Citalopram / Q000008:administration & dosage; D018592:Cross-Over Studies; D003533:Cyproheptadine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D009490:Neurosecretory Systems / Q000187:drug effects*; D010865:Pilot Projects; D011388:Prolactin / Q000097:blood; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin / Q000187:drug effects*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage
D015283:Citalopram; D003533:Cyproheptadine; D006854:Hydrocortisone; D011388:Prolactin; D044402:Receptor, Serotonin, 5-HT2A; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017367:Selective Serotonin Reuptake Inhibitors