Identification and localization of gonadotropin-inhibitory hormone (GnIH) orthologs in the hypothalamus of the red-eared slider turtle, Trachemys scripta elegans

Kazuyoshi Ukena, Eiko Iwakoshi-Ukena, Tomohiro Osugi, Kazuyoshi Tsutsui

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    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.

    Original languageEnglish
    Pages (from-to)69-76
    Number of pages8
    JournalGeneral and Comparative Endocrinology
    Publication statusPublished - 2016 Feb 1



    • cDNA cloning
    • Gonadotropin-inhibitory hormone (GnIH)
    • Hypothalamus
    • Neuropeptide
    • Turtle

    ASJC Scopus subject areas

    • Endocrinology

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