Central oxytocinergic and dopaminergic mechanisms regulating penile erection in conscious rats.
A series of in vivo studies in a conscious rat model was conducted to investigate the role of oxytocinergic and dopaminergic neurotransmission in the central regulation of penile erection. Oxytocin, when administrated either intracerebroventricularly (i.c.v.) or intrathecally (i.t.) at the spinal levels of L4-L6, produced dose-related erectogenic effects with a maximum at 0.1 microg/rat i.c.v. or 0.03 microg/rat i.t. Oxytocin-evoked penile activity was attenuated by the inhibitory effect of the selective oxytocin antagonist vasotocin analog [Pmp-Tyr(Me)-Ile-Thr-Asn-Cys]-Pro-Orn-Tyr-NH2 (0.1-1 microg, i.c.v. or i.t.). Penile erection induced by oxytocin was blocked by the dopaminergic receptor antagonist clozapine (1-10 micromol/kg i.p.) in a dose-dependent manner. Conversely, oxytocin antagonist microinjected locally (i.c.v. or i.t.) significantly attenuated the pro-erectile effects of systemic (s.c.) apomorphine, a centrally acting erectogenic agent through dopaminergic receptors. Together, these data indicate a possible concomitant role between dopamine and oxytocin in mediating penile erection at both the spinal and supraspinal sites.
Martino
Brenda
B
Global Neuroscience Research, Global Pharmaceutical Research and Development, Building AP9A, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064, USA. Brenda.martino@abbott.com
Hsieh
Gin C
GC
Hollingsworth
Peter R
PR
Mikusa
Joseph P
JP
Moreland
Robert B
RB
Bitner
R Scott
RS
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003024:Clozapine / Q000008:administration & dosage / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007276:Injections, Intraventricular; D007278:Injections, Spinal; D007279:Injections, Subcutaneous; D008297:Male; D008954:Models, Biological; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D010410:Penile Erection / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D014668:Vasotocin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D010121:Oxytocin; D003024:Clozapine; D001058:Apomorphine; D014668:Vasotocin