The effects of 5HT(1) agonists on erection in rats in vivo and rabbit corpus cavernosum in vitro.
We have examined the effects of the selective 5-HT(1a) and 5-HT(1b) agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) and 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]quinoxaline (CGS12066b), respectively on erection in rats in vivo and rabbit corpus cavernosum in vitro. Apomorphine (0.1 mg/kg) induced 3.1+/-0.4 erections in vehicle-pretreated animals. At the highest doses tested 8-OHDPAT (0.4-0.64 mg/kg) and CGS12066b (1.0-10.0 mg/kg) significantly reduced apomorphine erection to 0.9+/-0.3 erections and 0.5+/-0.2 erections respectively. The nonselective 5-HT agonist metachlorophenylpiperazine (m-CPP; 0.1 mg/kg) elicited characteristic increases in cavernous nerve activity (CNA) and intracavernous pressure responses (ICP) in anesthetized rats. 8-OHDPAT (0.64 mg/kg) and CGS12066b (1.0 mg/kg) failed to elicit CNA or ICP responses. CGS12066b reduced ICP responses resulting from the direct stimulation of the cavernous nerve whereas 8-OHDPAT did not. CGS12066b reduced the CNA and ICP responses to m-CPP administration whereas 8-OHDPAT potentiated m-CPP induced CNA and ICP responses. In isolated rabbit corpus cavernosum (CC) 8-OHDPAT and CGS12066b both failed to alter noradrenergic induced contraction and non-adrenergic non-cholinergic relaxation. Our results indicate that selective 5-HT(1a) and 5-HT(1b) agonists have different effects in different models of erection.
Hayes
E S
ES
The Department of Obstetrics and Gynaecology, The National University of Singapore, Singapore.
Adaikan
P G
PG
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D008297:Male; D009130:Muscle, Smooth / Q000502:physiology; D010410:Penile Erection / Q000187:drug effects*; D010413:Penis / Q000502:physiology; D011312:Pressure; D011810:Quinoxalines / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D018491:Dopamine Agonists; D011810:Quinoxalines; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists; C052561:CGS 12066B; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D001058:Apomorphine