Balfour M E, Brown J L, Yu L, Coolen L M
Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati Medical Center, Vontz Center for Molecular Studies, University of Cincinnati, 3125 Eden Avenue, ML-521, Cincinnati, OH 45267-0521, USA.
Neuroscience. 2006;137(4):1259-76. doi: 10.1016/j.neuroscience.2005.11.013. Epub 2006 Jan 4.
The limbic system plays an important role in the regulation of sexual motivation and reward. At the core of this system is an interconnected mesocorticolimbic circuit, comprised of the ventral tegmental area, nucleus accumbens and medial prefrontal cortex. Previously, our laboratory showed that sexual behavior causes neural activation in the ventral tegmental area of male rats. The main goal of this study is to identify afferent inputs to ventral tegmental area neurons that may contribute to their activation during sexual behavior. Hence, the anterograde tracer biotinylated dextran amine was injected into subregions of the rat medial prefrontal cortex, which is known to project to the ventral tegmental area. Visualization of biotinylated dextran amine-labeled axons was combined with immunostaining for sex-induced Fos expression. Quantitative analysis showed that the majority of sex-activated ventral tegmental area neurons receive putative contacts from the infralimbic and prelimbic--but not the anterior cingulate--subregions of the medial prefrontal cortex. Thus, inputs from infralimbic area and prelimbic are in an anatomical position to provide a major source of input during sexual behavior. A second goal of this study was to determine if the medial prefrontal cortex projects to sex-activated neurons in other brain regions important for sexual behavior and motivation. Infralimbic area and prelimbic area sent projections to nucleus accumbens, medial preoptic area, principal nucleus of the bed nucleus of the stria terminalis, basolateral amygdala, and parvocellular subparafasicular thalamic nucleus. Thus, the infralimbic and prelimbic subregions of the medial prefrontal cortex may also influence sexual behavior and motivation via brain regions other than the ventral tegmental area.
边缘系统在性动机和奖赏的调节中发挥着重要作用。该系统的核心是一个相互连接的中脑皮质边缘回路，由腹侧被盖区、伏隔核和内侧前额叶皮质组成。此前，我们实验室表明性行为会导致雄性大鼠腹侧被盖区的神经激活。本研究的主要目标是确定可能导致腹侧被盖区神经元在性行为期间激活的传入输入。因此，将顺行示踪剂生物素化葡聚糖胺注入大鼠内侧前额叶皮质的亚区域，已知该区域会投射到腹侧被盖区。对生物素化葡聚糖胺标记的轴突的可视化与对性诱导的Fos表达的免疫染色相结合。定量分析表明，大多数性激活的腹侧被盖区神经元接受来自内侧前额叶皮质的下缘和前边缘区（而非前扣带回）亚区域的假定联系。因此，来自下缘区和前边缘区的输入在解剖位置上为性行为期间的主要输入来源。本研究的第二个目标是确定内侧前额叶皮质是否投射到对性行为和动机重要的其他脑区中的性激活神经元。下缘区和前边缘区向伏隔核、内侧视前区、终纹床核的主核、基底外侧杏仁核和小细胞束旁丘脑核发送投射。因此，内侧前额叶皮质的下缘和前边缘亚区域也可能通过腹侧被盖区以外的脑区影响性行为和动机。
