Does metergoline selectively attenuate 5-HT mediated prolactin release?
Administration of the non-selective 5-HT receptor antagonist metergoline (0.5 mg/kg) to male rats attenuated the prolactin response to the 5-HT releasing agent d-fenfluramine (7.5 mg/kg) but not to the dopamine receptor antagonist haloperidol (1.5 mg/kg). In contrast, in healthy male volunteers, pretreatment with metergoline (4 mg orally) abolished the prolactin response to intravenous haloperidol (5 micrograms/kg). The findings suggest that in humans blockade of a prolactin response by a conventional oral dose of metergoline cannot be taken as evidence of involvement of 5-HT-mediated mechanisms.
Ellis
P M
PM
MRC Unit of Clinical Pharmacology, Littlemore Hospital, Oxford, UK.
Gartside
S E
SE
Ware
C J
CJ
Campling
G M
GM
Cowen
P J
PJ
D000293:Adolescent; D000328:Adult; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D005277:Fenfluramine / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D006801:Humans; D008297:Male; D008711:Metergoline / Q000494:pharmacology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology*
D012702:Serotonin Antagonists; D008711:Metergoline; D005277:Fenfluramine; D012701:Serotonin; D011388:Prolactin; D006220:Haloperidol