title: Moderate role of oxytocin in the pro-ejaculatory effect of the 5-HT1A receptor agonist 8-OH-DPAT.
abstract: BACKGROUND
  The neurobiological control of ejaculation is not completely understood. Both serotonin (5-HT) and oxytocin (OXT) play a role in the control of male sexual parameters, putatively via overlapping neuronal networks.
  
  
  OBJECTIVE
  The aim of this study was to determine whether activation of 5-HT1A receptors (5-HT1A Rs) reduces the ejaculatory threshold via the direct activation of (OXT) neurons in the paraventricular hypothalamic nucleus (PVN).
  
  
  METHODS
  In experiment 1, male rats received acute bilateral infusions of the selective 5-HT1A R antagonist WAY-100635 (1 and 10 μg) or vehicle into the PVN, followed by acute subcutaneous (s.c.) injection of the potent 5-HT1 A R agonist 8-OH-DPAT (0.4 mg/kg) or saline. In experiment 2, male rats received acute bilateral infusions of 8-OH-DPAT (1 and 10 μg) or vehicle into the PVN. In experiment 3, male rats received acute intracerebroventricular (i.c.v.) infusion of a selective OXT receptor antagonist (OXTR-A, 75 and 750 ng) followed by acute s.c. injection of 8-OH-DPAT (0.4 mg/kg) or saline. The effects of these drug treatments on sexual behavior were measured.
  
  
  METHODS
  Copulation latency, ejaculation latency, mount and intromission frequency, and ejaculation frequency of sexually experienced adult male Wistar rats during 30-minute sexual behavior tests with a receptive female were the main outcome measures.
  
  
  RESULTS
  Male sexual behavior was not affected by intra-PVN infusion of WAY-100635 or 8-OH-DPAT, or by i.c.v. infusion of OXTR-A alone. However, the facilitation of ejaculation (reduced mount and intromission frequency and ejaculation latency) induced by systemic 8-OH-DPAT could be attenuated by either intra-PVN infusion of WAY-100635 or by i.c.v. infusion of OXTR-A.
  
  
  CONCLUSIONS
  Activation of OXT neurons plays a moderate role in the pro-ejaculatory effects of systemic 8-OH-DPAT, but extracellular 5-HT levels may influence the strength of the effects.
authors.affiliation: Department of Behavioral and Molecular Neurobiology, University of Regensburg, Regensburg, Germany.
authors.forename: Trynke R
authors.initials: TR
authors.lastname: de Jong
authors.forename: Inga D
authors.initials: ID
authors.lastname: Neumann
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D004542:Ejaculation / Q000187:drug effects*; D008297:Male; D010121:Oxytocin / Q000187:drug effects*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D058825:Serotonin 5-HT1 Receptor Agonists / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D009435:Synaptic Transmission
chemical_list: D010879:Piperazines; D011725:Pyridines; D058825:Serotonin 5-HT1 Receptor Agonists; D012701:Serotonin; D010121:Oxytocin; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin
keywords: 8-OH-DPAT; Ejaculation; Oxytocin; Paraventricular Hypothalamic Nucleus; WAY-100635