Yamaguchi Shohei, Abe Yuta, Maejima Sho, Tsukahara Shinji
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan.
Area of Life-NanoBio, Division of Strategy Research, Graduate School of Science and Engineering, Saitama University, Saitama, 338-8570, Japan.
Neurosci Lett. 2018 Oct 15;685:155-159. doi: 10.1016/j.neulet.2018.08.037. Epub 2018 Aug 28.
The medial preoptic area (MPN) plays an important role in the control of male sexual behavior. In rats, the central part of the MPN (MPNc) is sexually dimorphic and contains a sexually dimorphic nucleus composed of neurons expressing calbindin-D28 K (CALB-SDN). Although the functions of the MPNc are not well understood, surgical destruction of the MPNc adversely affects the performance of sexual behavior in sexually naive males, but not in sexually experienced males, supporting the notion that the MPNc changes functionally with sexual experience. In this study, we aimed to determine the effects of sexual experience on the neuronal activity of the MPNc and CALB-SDN. Sexual behavior in sexually inexperienced males that had no experience of ejaculation, and experienced males that had ejaculated once was observed. After they displayed sexual behavior, the brains were sampled, and immunohistochemical analysis of c-Fos, a neuronal activity marker, in the MPNc and CALB-SDN was performed. The numbers of c-Fos-immunopositive cells with or without calbindin-D28K-immunoreactivity increased significantly in the MPNc and CALB-SDN following ejaculation in both sexually inexperienced and experienced males, although the numbers did not change significantly with exposure to estrous female odors, the first mount, and the first intromission before and after the first ejaculation. We further found that the number of c-Fos-immunopositive and calbindin-D28K-immunonegative cells in the MPNc, but not in the CALB-SDN, was significantly smaller in sexually experienced males than in sexually inexperienced males. These results suggest that a population of MPNc neurons, which is located outside the CALB-SDN and do not express calbindin-D28 K, are activated during the first copulation and then silent after acquisition of sexual experience.
内侧视前区（MPN）在雄性性行为控制中起重要作用。在大鼠中，MPN的中央部分（MPNc）具有性别二态性，包含一个由表达钙结合蛋白-D28K（CALB-SDN）的神经元组成的性别二态核。尽管对MPNc的功能了解不多，但对MPNc进行手术破坏会对性幼稚雄性的性行为表现产生不利影响，而对有性经验的雄性则没有影响，这支持了MPNc的功能会随性经验而改变的观点。在本研究中，我们旨在确定性经验对MPNc和CALB-SDN神经元活动的影响。观察了没有射精经验的性幼稚雄性和射精一次的有性经验雄性的性行为。在它们表现出性行为后，采集大脑样本，并对MPNc和CALB-SDN中神经元活动标记物c-Fos进行免疫组织化学分析。在性幼稚和有性经验的雄性射精后，MPNc和CALB-SDN中具有或不具有钙结合蛋白-D28K免疫反应性的c-Fos免疫阳性细胞数量均显著增加，尽管在第一次射精前后接触发情雌性气味、第一次爬跨和第一次插入时数量没有显著变化。我们进一步发现，有性经验雄性的MPNc中c-Fos免疫阳性且钙结合蛋白-D28K免疫阴性的细胞数量显著少于性幼稚雄性，但在CALB-SDN中并非如此。这些结果表明，位于CALB-SDN之外且不表达钙结合蛋白-D28K的一群MPNc神经元在第一次交配时被激活，在获得性经验后则保持沉默。
