Matsuda F, Nakatsukasa K, Suetomi Y, Naniwa Y, Ito D, Inoue N, Wakabayashi Y, Okamura H, Maeda K-I, Uenoyama Y, Tsukamura H, Ohkura S
Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan.
J Neuroendocrinol. 2015 Jan;27(1):57-65. doi: 10.1111/jne.12235.
A luteinising hormone (LH) surge is fundamental to the induction of ovulation in mammalian females. The administration of a preovulatory level of oestrogen evokes an LH surge in ovariectomised females, whereas the response to oestrogen in castrated males differs among species; namely, the LH surge-generating system is sexually differentiated in some species (e.g. rodents and sheep) but not in others (e.g. primates). In the present study, we aimed to determine whether there is a functional LH surge-generating system in male goats, and whether hypothalamic kisspeptin neurones in male goats are involved in the regulation of surge-like LH secretion. By i.v. infusion of oestradiol (E2; 6 μg/h) for 16 h, a surge-like LH increase occurred in both castrated male and ovariectomised female goats, although the mean peak LH concentration was lower and the mean peak of the LH surge was later in males compared to females. Dual staining with KISS1 in situ hybridisation and c-Fos immunohistochemistry revealed that E2 treatment significantly increased c-Fos expression in the medial preoptic area (mPOA) KISS1 cells in castrated males, as well as ovariectomised females. By contrast, dual-labelled cells were scarcely detected in the arcuate nucleus (ARC) after E2 treatment in both sexes. These data suggest that kisspeptin neurones in the mPOA, but not those in the ARC, are involved in the induction of surge-like LH secretion in both male and female goats. In summary, our data show that the mechanism that initiates the LH surge in response to oestrogen, the mPOA kisspeptin neurones, is functional in male goats. Thus, sexual differentiation of the LH surge-generating system would not be applicable to goats.
促黄体生成素（LH）峰是哺乳动物雌性排卵诱导的基础。给予排卵前水平的雌激素可在去卵巢雌性动物中引发LH峰，而阉割雄性动物对雌激素的反应在不同物种间存在差异；也就是说，LH峰产生系统在某些物种（如啮齿动物和绵羊）中存在性别差异，而在其他物种（如灵长类动物）中则不存在。在本研究中，我们旨在确定雄性山羊是否存在功能性的LH峰产生系统，以及雄性山羊下丘脑的吻肽神经元是否参与类似峰状LH分泌的调节。通过静脉注射雌二醇（E2；6μg/h）16小时，去势雄性和去卵巢雌性山羊均出现了类似峰状的LH升高，尽管雄性的平均LH峰值浓度较低，且LH峰的平均峰值出现时间比雌性晚。KISS1原位杂交和c-Fos免疫组化双重染色显示，E2处理显著增加了去势雄性和去卵巢雌性山羊内侧视前区（mPOA）KISS1细胞中的c-Fos表达。相比之下，两性在E2处理后，弓状核（ARC）中几乎未检测到双标记细胞。这些数据表明，mPOA中的吻肽神经元而非ARC中的吻肽神经元参与了雄性和雌性山羊类似峰状LH分泌的诱导。总之，我们的数据表明，响应雌激素引发LH峰的机制，即mPOA吻肽神经元，在雄性山羊中具有功能。因此，LH峰产生系统的性别分化不适用于山羊。
