Bentley G E, Ubuka T, McGuire N L, Calisi R, Perfito N, Kriegsfeld L J, Wingfield J C, Tsutsui K
Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
J Neuroendocrinol. 2009 Mar;21(4):276-81. doi: 10.1111/j.1365-2826.2009.01851.x.
Gonadotrophin-inhibitory hormone (GnIH) was discovered 8 years ago in birds. Its identification raised the possibility that gonadotrophin-releasing hormone (GnRH) is not the sole hypothalamic neuropeptide that directly influences pituitary gonadotrophin release. Initial studies on GnIH focused on the avian anterior pituitary as comprising the only physiological target of GnIH. There are now several lines of evidence indicating that GnIH directly inhibits pituitary gonadotrophin synthesis and release in birds and mammals. Histological studies on projections from hypothalamic GnIH neurones subsequently implied direct actions of GnIH within the brain and in the periphery. In addition to actions on the pars distalis via the median eminence, GnIH axons and terminals are present in multiple brain areas in birds, and the GnIH receptor is expressed on GnRH-I and -II neurones. Furthermore, we have demonstrated the presence of GnIH and its receptor in avian and mammalian gonads. Thus, GnIH can act directly at multiple levels: within the brain, on the pituitary and in the gonads. In sum, our data indicate that GnIH and its related peptides are important modulators of reproductive function at the level of the GnRH neurone, the gonadotroph and the gonads. Here, we provide an overview of the known levels of GnIH action in birds and mammals. In addition, environmental and physiological factors that are involved in GnIH regulation are reviewed.
促性腺激素抑制激素（GnIH）于8年前在鸟类中被发现。它的发现增加了促性腺激素释放激素（GnRH）并非唯一直接影响垂体促性腺激素释放的下丘脑神经肽的可能性。对GnIH的初步研究聚焦于鸟类垂体前叶，认为其是GnIH唯一的生理靶标。现在有几条证据表明，GnIH在鸟类和哺乳动物中直接抑制垂体促性腺激素的合成与释放。随后对下丘脑GnIH神经元投射的组织学研究表明，GnIH在脑内和外周均有直接作用。除了通过正中隆起作用于远侧部外，鸟类多个脑区均存在GnIH轴突和终末，且GnIH受体在GnRH - I和 - II神经元上表达。此外，我们已经证明鸟类和哺乳动物性腺中存在GnIH及其受体。因此，GnIH可在多个水平直接发挥作用：在脑内、垂体以及性腺。总之，我们的数据表明，GnIH及其相关肽是GnRH神经元、促性腺激素细胞和性腺水平上生殖功能的重要调节因子。在此，我们概述了鸟类和哺乳动物中已知的GnIH作用水平。此外，还综述了参与GnIH调节的环境和生理因素。
