title: Dopamine D1 receptor agonists induce penile erections in rats.
abstract: The dopamine receptor agonist apomorphine has been recently introduced in the treatment of erectile dysfunction. While it is well established that dopamine D2-like receptors play a crucial role in this effect, conflicting result are reported in the literature as for the role of dopamine D1-like receptors. The aim of this study was to determine the effect of systemic administration of dopamine D1-like receptor agonists on penile erection in rats. Male Wistar rats were treated with three different, and not structurally related, dopamine D1-like receptor agonists: the partial agonists SKF38393 ((+) 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine) and CY 208-243 ((-)-4,6,6a,7,8,12b-exahydro-7-methylindole [4,3-ab]fenantridine), and the full agonist A 77636 ((-)-(1R,3S)-3-Adamantyl-1-(aminomethyl)-3,4-dihydro-5,6-dihydroxy-1H-2-benzopyran hydrochloride). All three compounds dose-dependently increased the number of penile erections, with the full agonist A77636 showing a more pronounced effect with respect to the other two. Moreover, the dopamine D1-like receptor antagonist SCH 23390 ((R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine) dose-dependently antagonised A77636 effect. These results show that systemic administration of dopamine D1-like receptor agonists induce penile erection in rats. This observation suggests that dopamine D1-like receptor agonists might be considered as a possible alternative to apomorphine in the treatment of erectile dysfunction, thus avoiding the typical side effects related to the stimulation of dopamine D2-like receptors such as nausea.
authors.affiliation: Dipartimento di Scienze del Farmaco, Università di Sassari, Via Muroni 23/A, 07100 Sassari, Italy. dsfpaolo@uniss.it
authors.forename: Paolo S
authors.initials: PS
authors.lastname: D'Aquila
authors.forename: Francesca
authors.initials: F
authors.lastname: Panin
authors.forename: Maria
authors.initials: M
authors.lastname: Cossu
authors.forename: Alessandra T
authors.initials: AT
authors.lastname: Peana
authors.forename: Gino
authors.initials: G
authors.lastname: Serra
mesh_terms: D000818:Animals; D018491:Dopamine Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D008297:Male; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000819:agonists* / Q000502:physiology*
chemical_list: D018491:Dopamine Agonists; D017447:Receptors, Dopamine D1