Sanna Fabrizio, Bratzu Jessica, Piludu Maria A, Corda Maria G, Melis Maria R, Giorgi Osvaldo, Argiolas Antonio
Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, and Centre of Excellence for the Neurobiology of Addictions, University of CagliariCagliari, Italy.
Department of Life and Environmental Sciences, Section of Pharmaceutical, Pharmacological and Nutraceutical Sciences, University of CagliariCagliari, Italy.
Front Behav Neurosci. 2017 Jun 7;11:108. doi: 10.3389/fnbeh.2017.00108. eCollection 2017.
Roman High- (RHA) and Low-Avoidance (RLA) outbred rats, which differ for a respectively rapid vs. poor acquisition of the active avoidance response in the shuttle-box, display differences in sexual activity when put in the presence of a sexually receptive female rat. Indeed RHA rats show higher levels of sexual motivation and copulatory performance than RLA rats, which persist also after repeated sexual activity. These differences have been correlated to a higher tone of the mesolimbic dopaminergic system of RHA rats vs. RLA rats, revealed by the higher increase of dopamine found in the dialysate obtained from the nucleus accumbens of RHA than RLA rats during sexual activity. This work shows that extracellular dopamine and noradrenaline (NA) also, increase in the dialysate from the medial prefrontal cortex (mPFC) of male RHA and RLA rats put in the presence of an inaccessible female rat and more markedly during direct sexual interaction. Such increases in dopamine (and its main metabolite 3,4-dihydroxyphenylacetic acid, DOPAC) and NA were found in both sexually naïve and experienced animals, but they were higher: (i) in RHA than in RLA rats; and (ii) in sexually experienced RHA and RLA rats than in their naïve counterparts. Finally, the differences in dopamine and NA in the mPFC occurred concomitantly to those in sexual activity, as RHA rats displayed higher levels of sexual motivation and copulatory performance than RLA rats in both the sexually naïve and experienced conditions. These results suggest that a higher dopaminergic tone also occurs in the mPFC, together with an increased noradrenergic tone, which may be involved in the different copulatory patterns found in RHA and RLA rats, as suggested for the mesolimbic dopaminergic system.
罗马高回避型（RHA）和低回避型（RLA）远交系大鼠在穿梭箱中主动回避反应的习得速度上分别表现为快速和较差，当它们与处于性接受期的雌性大鼠共处时，在性活动方面存在差异。事实上，RHA大鼠比RLA大鼠表现出更高水平的性动机和交配能力，且这种差异在反复性活动后依然存在。这些差异与RHA大鼠相较于RLA大鼠中脑边缘多巴胺能系统更高的兴奋性有关，这一点通过性活动期间从RHA大鼠伏隔核获得的透析液中多巴胺的增加幅度高于RLA大鼠得以揭示。这项研究表明，当雄性RHA和RLA大鼠与无法接触的雌性大鼠共处时，尤其是在直接性互动期间，内侧前额叶皮质（mPFC）透析液中的细胞外多巴胺和去甲肾上腺素（NA）也会增加。在性幼稚和有性经验的动物中均发现多巴胺（及其主要代谢产物3,4 - 二羟基苯乙酸，DOPAC）和NA的这种增加，但它们更高：（i）在RHA大鼠中比在RLA大鼠中；（ii）在有性经验的RHA和RLA大鼠中比在它们性幼稚的对应大鼠中。最后，mPFC中多巴胺和NA的差异与性活动中的差异同时出现，因为在性幼稚和有性经验的条件下，RHA大鼠均比RLA大鼠表现出更高水平的性动机和交配能力。这些结果表明，mPFC中也存在更高的多巴胺能兴奋性，同时去甲肾上腺素能兴奋性增加，这可能与RHA和RLA大鼠中发现的不同交配模式有关，就像中脑边缘多巴胺能系统的情况一样。
