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Title: Central dopamine and oxytocin interactions during penile erection
Author: Baskerville, Tracey Anne
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2008
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Using Sprague-Dawley male rats, part 1 investigated the effects of D2, D3 and D4 receptor agonists on penile erection or antagonists on intromitting behaviours and the effect of these dopaminergic ligands on the activation of oxytocin neurons in the MPN, SON and PVN. The D2/D3 and D4 agonist were clearly pro-erectile with the D2/D3 agonist significantly activating oxytocin neurons in the parvocellular PVN (pPVN). The D4 antagonist decreased intromitting behaviour in addition to attenuating oxytocin activation in the SON of intromitting males. In part 2, brains from untreated male rats were processed by double immunofluorescence for D2, D3 or D4 receptor and oxytocin in the MPN, SON and PVN. D2, D3 and D4 receptors were each shown separately to colocalise with oxytocin neurons in the MPN, SON and PVN. In part 3, both intracavernous pressure (ICP) and blood pressure were recorded and analysed in urethane-anaesthetised male rats. Two studies were performed, in study 1, the ICP response to i.v. apomorphine (0.25mg/kg) after intra-thecal (i.t.) pre-treatment with the oxytocin receptor antagonist (OXA) (36, 180 and 900 ng) (3μl) were observed. The OXA (180 and 900ng) significantly decreased the incidence and mean number of apomorphine-induced erections. In study 2, using push-pull perfusion, oxytocin release in the lumbosacral spinal cord was compared after i.v. delivery of apomorphine (0.25mg/kg) or saline. Apomorphine non-significantly increased oxytocin levels in the lumbosacral spinal when compared to vehicle. In conclusion, dopamine elicits penile erection in part via the stimulation of D4 receptors (perhaps located on oxytocin neurons) and activating oxytocin pathways in the SON. Additionally, such dopamine-mediated penile erection may also involve a modulatory role of spinal oxytocin.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available