5-HT1A receptor blockade increases penile erections induced by indirect serotonin agonists.
Indirect serotonergic agonists, whether promoters of 5-HT release such as fenfluramine (5 mg kg-1) or inhibitors of 5-HT uptake such as fluoxetine (10 mg kg-1), elicited in rats penile erections at a modest but significant level. Their effects were markedly potentiated by the beta-blocker tertatolol, (0.6-5 mg kg-1) which displays 5-HT1A receptor blocking activity, but not by the beta-blocker labetalol (6.25 and 25 mg kg-1), which lacks such activity. In addition, tertatolol, but not labetalol, potentiated penile erections induced by meta-chloro-phenylpiperazine (1 mg kg-1). Thus, it appears that increasing serotonergic transmission increases only moderately penile erections because of the functional opposition exerted by 5-HT1A (inhibition) and 5-HT1C (activation) serotonin receptors on this response.
Simon
P
P
Unité de Neuropsychopharmacologie expérimentale, U.R.A. 1170 du C.N.R.S., Faculté de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France.
Bertrand
J
J
Costentin
J
J
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D004357:Drug Synergism; D005277:Fenfluramine / Q000494:pharmacology; D005473:Fluoxetine / Q000494:pharmacology; D007741:Labetalol / Q000494:pharmacology; D008297:Male; D010410:Penile Erection / Q000187:drug effects*; D010879:Piperazines / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013876:Thiophenes
D000319:Adrenergic beta-Antagonists; D010879:Piperazines; D011412:Propanolamines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D013876:Thiophenes; D005473:Fluoxetine; D005277:Fenfluramine; C005632:tertatolol; D007741:Labetalol; C015068:1-(3-chlorophenyl)piperazine