Gonadotrophin-Inhibitory Hormone in the Cichlid Fish Cichlasoma dimerus

Structure, Brain Distribution and Differential Effects on the Secretion of Gonadotrophins and Growth Hormone

M. P. Di Yorio, D. I. Pérez Sirkin, T. H. Delgadin, A. Shimizu, Kazuyoshi Tsutsui, G. M. Somoza, P. G. Vissio

    Research output: Contribution to journalArticle

    18 Citations (Scopus)

    Abstract

    The role of gonadotrophin-inhibitory hormone (GnIH) in the inhibition of the reproductive axis has been well-established in birds and mammals. However, its role in other vertebrates, such as the teleost fish, remains controversial. In this context, the present study aimed to evaluate whether GnIH modulates the release of gonadotrophins and growth hormone (GH) in the cichlid fish Cichlasoma dimerus. First, we partially sequenced the precursor polypeptide for GnIH and identified three putative GnIH peptides. Next, we analysed the expression of this precursor polypeptide via a polymerase chain reaction in the reproductive axis of both sexes. We found a high expression of the polypeptide in the hypothalamus and gonads of males. Immunocytochemistry allowed the observation of GnIH-immunoreactive somata in the nucleus posterioris periventricularis and the nucleus olfacto-retinalis, with no differences between the sexes. GnIH-immunoreactive fibres were present in all brain regions, with a high density in the nucleus lateralis tuberis and at both sides of the third ventricle. Finally, we performed in vitro studies on intact pituitary cultures to evaluate the effect of two doses (10−6 m and 10−8 m) of synthetic C. dimerus (cd-) LPQRFa-1 and LPQRFa-2 on the release of gonadotrophins and GH. We observed that cd-LPQRFa-1 decreased β-luteinising hormone (LH) and β-follicle-stimulating hormone (FSH) and also increased GH release to the culture medium. The release of β-FSH was increased only when it was stimulated with the higher cd-LPQRFa-2 dose. The results of the present study indicate that cd-LPQRFa-1, the cichlid fish GnIH, inhibits β-LH and β-FSH release and stimulates GH release in intact pituitary cultures of C. dimerus. The results also show that cd-LPQRF-2 could act as an β-FSH-releasing factor in this fish species.

    Original languageEnglish
    JournalJournal of Neuroendocrinology
    Volume28
    Issue number5
    DOIs
    Publication statusPublished - 2016 May 1

    Fingerprint

    Cichlids
    Gonadotropins
    Growth Hormone
    Hormones
    Brain
    Follicle Stimulating Hormone
    Luteinizing Hormone
    Peptides
    Fishes
    Third Ventricle
    Peptide Hormones
    Gonads
    Carisoprodol
    Sex Characteristics
    Hypothalamus
    Birds
    Culture Media
    Vertebrates
    Mammals
    Immunohistochemistry

    Keywords

    • fish
    • follicle-stimulating hormone
    • gonadotrophin-inhibitory hormone
    • growth hormone
    • luteinising hormone

    ASJC Scopus subject areas

    • Endocrinology, Diabetes and Metabolism
    • Endocrinology
    • Endocrine and Autonomic Systems
    • Cellular and Molecular Neuroscience

    Cite this

    Gonadotrophin-Inhibitory Hormone in the Cichlid Fish Cichlasoma dimerus : Structure, Brain Distribution and Differential Effects on the Secretion of Gonadotrophins and Growth Hormone. / Di Yorio, M. P.; Pérez Sirkin, D. I.; Delgadin, T. H.; Shimizu, A.; Tsutsui, Kazuyoshi; Somoza, G. M.; Vissio, P. G.

    In: Journal of Neuroendocrinology, Vol. 28, No. 5, 01.05.2016.

    Research output: Contribution to journalArticle

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    abstract = "The role of gonadotrophin-inhibitory hormone (GnIH) in the inhibition of the reproductive axis has been well-established in birds and mammals. However, its role in other vertebrates, such as the teleost fish, remains controversial. In this context, the present study aimed to evaluate whether GnIH modulates the release of gonadotrophins and growth hormone (GH) in the cichlid fish Cichlasoma dimerus. First, we partially sequenced the precursor polypeptide for GnIH and identified three putative GnIH peptides. Next, we analysed the expression of this precursor polypeptide via a polymerase chain reaction in the reproductive axis of both sexes. We found a high expression of the polypeptide in the hypothalamus and gonads of males. Immunocytochemistry allowed the observation of GnIH-immunoreactive somata in the nucleus posterioris periventricularis and the nucleus olfacto-retinalis, with no differences between the sexes. GnIH-immunoreactive fibres were present in all brain regions, with a high density in the nucleus lateralis tuberis and at both sides of the third ventricle. Finally, we performed in vitro studies on intact pituitary cultures to evaluate the effect of two doses (10−6 m and 10−8 m) of synthetic C. dimerus (cd-) LPQRFa-1 and LPQRFa-2 on the release of gonadotrophins and GH. We observed that cd-LPQRFa-1 decreased β-luteinising hormone (LH) and β-follicle-stimulating hormone (FSH) and also increased GH release to the culture medium. The release of β-FSH was increased only when it was stimulated with the higher cd-LPQRFa-2 dose. The results of the present study indicate that cd-LPQRFa-1, the cichlid fish GnIH, inhibits β-LH and β-FSH release and stimulates GH release in intact pituitary cultures of C. dimerus. The results also show that cd-LPQRF-2 could act as an β-FSH-releasing factor in this fish species.",
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    AU - Pérez Sirkin, D. I.

    AU - Delgadin, T. H.

    AU - Shimizu, A.

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