title: Penile erection and yawning induced by dopamine D2-like receptor agonists in rats: influence of strain and contribution of dopamine D2, but not D3 and D4 receptors.
abstract: Dopamine (DA) is implicated in penile erection (PE) and yawning (YA) in rats through activation of D2-like receptors. However, the exact role of each subtype (D2, D3 and D4) of this receptor family in PE/YA is still not clearly elucidated. We recorded concomitantly PE and YA after treatment with agonists with various levels of selectivity for the different subtypes of D2-like receptors. In addition, we investigated the efficacy of antagonists with selective or preferential affinity for each of the three receptor subtypes to prevent apomorphine-induced PE and YA. Wistar rats were more sensitive than Long-Evans rats to the erectogenic activity of the nonselective DA agonist apomorphine (0.01-0.08 mg/kg), whereas Sprague-Dawley rats were insensitive. However, all the three strains were equally sensitive to apomorphine-induced YA. In Wistar rats, apomorphine (0.01-0.63 mg/kg), the D2/D3 agonists quinelorane and (+)7-OH-DPAT (0.000625-10 mg/kg) or PD 128,907 (0.01-10 mg/kg), but not the D4 agonists PD-168,077, RO-10-5824 and ABT-724 (0.04-0.63 mg/kg), produced PE and YA with bell-shaped dose-response curves. Similarly, ABT-724 and CP226-269 (another D4 agonist) failed to elicit PE and YA in Sprague-Dawley rats. Furthermore, in Wistar rats, PE and YA elicited by apomorphine (0.08 mg/kg) were not modified by selective D3 (S33084 and SB-277011, 0.63-10 mg/kg) or D4 (L-745,870 and RBI-257, 0.63-2.5 mg/kg) antagonists, but were prevented by the preferential D2 blocker L-741,626 (near-full antagonism at 2.5 mg/kg). The present data do not support a major implication of either DA D3 or D4 receptors in the control of PE and YA in rats, but indicate a preponderant role of DA D2 receptors.
authors: Division of Neurobiology 2, Centre de Recherche Pierre Fabre, Castres, France. ronan.depoortere@pierre-fabre.com
authors: Ronan
authors: R
authors: Depoortère
authors: Laurent
authors: L
authors: Bardin
authors: Michael
authors: M
authors: Rodrigues
authors: Erika
authors: E
authors: Abrial
authors: Monique
authors: M
authors: Aliaga
authors: Adrian
authors: A
authors: Newman-Tancredi
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D010410:Penile Erection / Q000187:drug effects*; D051381:Rats; D020318:Rats, Long-Evans; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000819:agonists*; D050637:Receptors, Dopamine D3 / Q000819:agonists* / Q000037:antagonists & inhibitors; D050638:Receptors, Dopamine D4 / Q000819:agonists* / Q000037:antagonists & inhibitors; D013045:Species Specificity; D015000:Yawning / Q000187:drug effects*
chemical_list: D018491:Dopamine Agonists; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4; D001058:Apomorphine