Dopamine-oxytocin interactions in penile erection

Dopamine and oxytocin have established roles in the central regulation of penile erection in rats; however, the neural circuitries involved in a specific erectile context and the interaction between dopamine and oxytocin mechanisms remain to be elucidated. The medial preoptic area (MPOA), supraoptic...

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Bibliographic Details
Published in:	The European journal of neuroscience Vol. 30; no. 11; pp. 2151 - 2164
Main Authors:	Baskerville, T. A., Allard, J., Wayman, C., Douglas, A. J.
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Publishing Ltd 01-12-2009
Subjects:	Animals Apomorphine - pharmacology Blood Pressure - drug effects Dopamine - metabolism Dopamine Agonists - pharmacology Dopamine Antagonists - pharmacology Dose-Response Relationship, Drug Drug Interactions Fos expression Hormone Antagonists - pharmacology Injections, Intraventricular - methods intracavernous pressure magnocellular neurons Male medial preoptic area Oxytocin - metabolism Paraventricular Hypothalamic Nucleus - drug effects Paraventricular Hypothalamic Nucleus - metabolism paraventricular nucleus Penile Erection - drug effects Penile Erection - psychology Preoptic Area - drug effects Preoptic Area - metabolism Proto-Oncogene Proteins c-fos - metabolism Rats Rats, Sprague-Dawley Receptors, Dopamine - metabolism Receptors, Oxytocin - antagonists & inhibitors Sexual Behavior, Animal - drug effects Spinal Cord - drug effects Spinal Cord - metabolism Statistics, Nonparametric supraoptic nucleus
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Summary:	Dopamine and oxytocin have established roles in the central regulation of penile erection in rats; however, the neural circuitries involved in a specific erectile context and the interaction between dopamine and oxytocin mechanisms remain to be elucidated. The medial preoptic area (MPOA), supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus may serve as candidate sites because they contain oxytocin cells, receive dopaminergic inputs and have been implicated in mediating masculine sexual behavior. Double immunofluorescence revealed that substantial numbers of oxytocin cells in the MPOA, SON and PVN possess dopamine D2, D3 and D4 receptors. In anaesthetized rats, using intracavernous pressure as a physiological indicator of erection, blockade of lumbosacral oxytocin receptors (UK, 427843) reduced erectile responses to a nonselective dopamine agonist (apomorphine), suggesting that dopamine recruits a paraventriculospinal oxytocin pathway. In conscious males in the absence of a female, penile erection elicited by a D2/D3 (Quinelorane) but not D4 (PD168077) agonist was associated with activation of medial parvocellular PVN oxytocin cells. In another experiment where males were given full access to a receptive female, a D4 (L‐745870) but not D2 or D3 antagonist (L‐741626; nafadotride) inhibited penile erection (intromission), and this was correlated with SON magnocellular oxytocin neuron activation. Together, the data suggest dopamine’s effects on hypothalamic oxytocin cells during penile erection are context‐specific. Dopamine may act via different parvocellular and magnocellular oxytocin subpopulations to elicit erectile responses, depending upon whether intromission is performed. This study demonstrates the potential existence of interaction between central dopamine and oxytocin pathways during penile erection, with the SON and PVN serving as integrative sites.
Bibliography:	ark:/67375/WNG-WPF7QFKR-K istex:E38C7802304BFC238CCC9105C6BF17733D9D4595 ArticleID:EJN6999 Division of Clinical, Neuroscience, University of Glasgow, Wellcome Surgical Institute, Garscube Estate, Glasgow G61 1QH, UK Present address ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0953-816X 1460-9568
DOI:	10.1111/j.1460-9568.2009.06999.x