Ukena Kazuyoshi, Iwakoshi-Ukena Eiko, Osugi Tomohiro, Tsutsui Kazuyoshi
Section of Behavioral Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan.
Section of Behavioral Sciences, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan.
Gen Comp Endocrinol. 2016 Feb 1;227:69-76. doi: 10.1016/j.ygcen.2015.06.009. Epub 2015 Jun 27.
Gonadotropin-inhibitory hormone (GnIH) was discovered in 2000 as a novel hypothalamic neuropeptide that inhibited gonadotropin release in the Japanese quail. GnIH and its orthologs have a common C-terminal LPXRFamide (X=L or Q) motif, and have been identified in vertebrates from agnathans to humans, apart from reptiles. In the present study, we characterized a cDNA encoding GnIH orthologs in the brain of the red-eared slider turtle. The deduced precursor protein consisted of 205 amino-acid residues, encoding three putative peptide sequences that included the LPXRFamide motif at their C-termini. In addition, the precursor sequence was most similar to those of avian species. Immunoaffinity purification combined with mass spectrometry confirmed that three mature peptides were produced in the brain. In situ hybridization and immunohistochemistry showed that turtle GnIH-containing cells were restricted to the periventricular hypothalamic nucleus. Immunoreactive fibers were densely distributed in the median eminence. Thus, GnIH and related peptides may act on the pituitary to regulate pituitary hormone release in turtles as well as other vertebrates.
促性腺激素抑制激素（GnIH）于2000年被发现，是一种新型下丘脑神经肽，可抑制日本鹌鹑的促性腺激素释放。GnIH及其直系同源物具有共同的C末端LPXRFamide（X = L或Q）基序，除爬行动物外，已在从无颌类到人类的脊椎动物中被鉴定出来。在本研究中，我们对红耳龟脑中编码GnIH直系同源物的cDNA进行了表征。推导的前体蛋白由205个氨基酸残基组成，编码三个推定的肽序列，其C末端包含LPXRFamide基序。此外，前体序列与鸟类物种的序列最为相似。免疫亲和纯化结合质谱法证实，脑中产生了三种成熟肽。原位杂交和免疫组织化学表明，含龟GnIH的细胞局限于室周下丘脑核。免疫反应性纤维密集分布在正中隆起。因此，GnIH和相关肽可能作用于垂体，以调节龟类以及其他脊椎动物的垂体激素释放。
