Maekawa Fumihiko, Nagino Koki, Yang Jiaxin, Htike Nang T T, Tsukahara Shinji, Ubuka Takayoshi, Tsutsui Kazuyoshi, Kawashima Takaharu
National Institute for Environmental Studies, Tsukuba, Japan; Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan.
National Institute for Environmental Studies, Tsukuba, Japan; Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan.
Gen Comp Endocrinol. 2018 Jan 15;256:63-70. doi: 10.1016/j.ygcen.2017.07.025. Epub 2017 Jul 29.
The National Institute for Environmental Studies (NIES) of Japan established a strain of Japanese quail (Coturnix japonica) known as NIES-L by rotation breeding in a closed colony for over 35years; accordingly, the strain has highly inbred-like characteristics. Another strain called NIES-Brn has been maintained by randomized breeding in a closed colony to produce outbred-like characteristics. The current study aimed to characterize intermale aggressive behaviors in both strains and to identify possible factors regulating higher aggression in the hypothalamus, such as sex hormone and neuropeptide expression. Both strains displayed a common set of intermale aggressive behaviors that included pecking, grabbing, mounting, and cloacal contact behavior, although NIES-Brn quail showed significantly more grabbing, mounting, and cloacal contact behavior than did NIES-L quail. We examined sex hormone levels in the blood and diencephalon in both strains. Testosterone concentrations were significantly higher in the blood and diencephalon of NIES-Brn quail compared to NIES-L quail. We next examined gene expression in the hypothalamus of both strains using an Agilent gene expression microarray and real-time RT-PCR and found that gene expression of mesotocin (an oxytocin homologue) was significantly higher in the hypothalamus of NIES-Brn quail compared to NIES-L quail. Immunohistochemistry of the hypothalamus revealed that numbers of large cells (cell area>500μm) expressing mesotocin were significantly higher in the NIES-Brn strain compared to the NIES-L strain. Taken together, our findings suggest that higher testosterone and mesotocin levels in the hypothalamus may be responsible for higher aggression in the NIES-Brn quail strain.
日本国立环境研究所（NIES）通过在封闭群体中进行超过35年的轮回选育，培育出了一种名为NIES-L的日本鹌鹑（Coturnix japonica）品系；因此，该品系具有高度近交系的特征。另一个名为NIES-Brn的品系则通过在封闭群体中进行随机选育来保持远交系的特征。本研究旨在描述这两个品系雄性间的攻击行为特征，并确定下丘脑调节更高攻击性的可能因素，如性激素和神经肽表达。两个品系都表现出一组共同的雄性间攻击行为，包括啄、抓、骑跨和泄殖腔接触行为，尽管NIES-Brn鹌鹑表现出的抓、骑跨和泄殖腔接触行为明显多于NIES-L鹌鹑。我们检测了两个品系血液和间脑中的性激素水平。与NIES-L鹌鹑相比，NIES-Brn鹌鹑血液和间脑中的睾酮浓度显著更高。接下来，我们使用安捷伦基因表达微阵列和实时RT-PCR检测了两个品系下丘脑的基因表达，发现与NIES-L鹌鹑相比，NIES-Brn鹌鹑下丘脑中中催产素（一种催产素同系物）的基因表达显著更高。下丘脑免疫组织化学显示，与NIES-L品系相比，NIES-Brn品系中表达中催产素的大细胞（细胞面积>500μm）数量显著更多。综上所述，我们的研究结果表明，下丘脑中较高的睾酮和中催产素水平可能是NIES-Brn鹌鹑品系更高攻击性的原因。
