Dopamine agonist-induced penile erection and yawning: Differential role of D₂-like receptor subtypes and correlation with nitric oxide production in the paraventricular nucleus of the hypothalamus of male rats

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• 作者：Fabrizio Sanna^a ; ¹ ; Salvatora Succu^a ; Maria Rosaria Melis^a ; Antonio Argiolas^a ; ^b ; ^{argiolas@unica.it}
• 关键词：Dopamine agonists ; Dopamine antagonists ; Nitric oxide ; Oxytocin ; Penile erection ; Yawning ; Paraventricular nucleus
• 刊名：Behavioural Brain Research
• 出版年：2012
• 期刊代码：3_01664328
• 类别：neu
• 出版时间：1 May, 2012
• 卷：230
• 期：2
• 页码：355-364
• 文件大小：1086 K

摘要

The dopamine D₃ preferring agonist pramipexole (50 ng) induced penile erection and yawning when injected into the paraventricular nucleus of the hypothalamus of male rats, like the mixed D₁/D₂-like agonist apomorphine (50 ng), while the D₄ agonist PD 168,077 (100 ng), induced penile erection only. These responses lasted for 45-60 min and occurred with an increase of NO₂鈭?and NO₃鈭?concentrations in the dialysate obtained from the paraventricular nucleus by intracerebral microdialysis. Pramipexole and apomorphine responses were reduced by the D₂ preferring antagonist L-741,626 (5 渭g), but not by the D₃ preferring antagonist SB-277011A (10 渭g), or the D₄ preferring antagonist L-745,870 (5 渭g), injected into the PVN before the dopamine agonist. In contrast, PD 168,077 responses were reduced by L-745,870, but not by L-741,626 or SB-277011A. Pramipexole, apomorphine and PD 168,077 effects were also reduced by the nitric oxide synthase inhibitor S-methyl-l-thiocitrulline (20 渭g) and the N-type voltage-dependent Ca²⁺ channels blocker 蠅-conotoxin (5 ng), given into the paraventricular nucleus, and by the oxytocin antagonist d(CH₂)₅Tyr(Me)²-Orn⁸-vasotocin (2 渭g), given intracerebroventricularly but not into the paraventricular nucleus before dopamine agonists. These results suggest that stimulation of D₂, but not D₃ or D₄ receptors, by pramipexole or apomorphine increases Ca²⁺ influx in cell bodies of oxytocinergic neurons. This increases the production of nitric oxide, which activates oxytocinergic neurotransmission in extra-hypothalamic brain areas and spinal cord, leading to penile erection and yawning. However, the stimulation of D₄ receptors by PD 168,077 also increases Ca²⁺ influx/nitric oxide production leading to penile erection, but not yawning.