Morphological relationship between GnIH and GnRH neurons in the brain of the neotropical cichlid fish Cichlasoma dimerus

María P. Di Yorio, Daniela I. Pérez Sirkin, José A. Muñoz-Cueto, Tomás H. Delgadin, Kazuyoshi Tsutsui, Gustavo M. Somoza, Paula G. Vissio

    Research output: Contribution to journalArticle

    3 Citations (Scopus)

    Abstract

    Reproduction is regulated by the hypothalamic-pituitary-gonadal axis. The first neuropeptide identified that regulates this function was the decapeptide gonadotropin-releasing hormone (GnRH). Nowadays, in gnatostomates, a number of GnRH variants have been identified and classified into three different types: GnRH1, GnRH2, and GnRH3. Almost 30 years later, a new peptide that inhibits gonadotropin synthesis and secretion was discovered and thus named as gonadotropin-inhibitory hormone (GnIH). In avians and mammals, the interaction and regulation between GnRH and GnIH neurons has been widely studied; however, in other vertebrate groups there is little information about the relationship between these neurons. In previous works, three GnRH variants and a GnIH propeptide were characterized in Cichlasoma dimerus, and it was demonstrated that GnIH inhibited gonadotropins release in this species. Because no innervation was detected at the pituitary level, we speculate that GnIH would inhibit gonadotropins via GnRH. Thus, the aim of the present study was to evaluate the anatomical relationship between neurons expressing GnIH and the three GnRH variants by double labelling confocal immunofluorescence in adults of C. dimerus. Our results showed no apparent contacts between GnIH and GnRH1, fiber to fiber interactions between GnIH and GnRH2, and co-localization of GnIH and GnRH3 variant in neurons of the nucleus olfacto-retinalis. In conclusion, whether GnIH regulates the expression or secretion of GnRH1 in this species, an indirect modulation seems more plausible. Moreover, the present results suggest an interaction between GnIH and GnRH2 systems. Finally, new clues were provided to investigate the role of nucleus olfacto-retinalis cells and putative GnIH and GnRH3 interactions in the modulation of the reproductive network in teleost fish.

    Original languageEnglish
    JournalGeneral and Comparative Endocrinology
    DOIs
    Publication statusAccepted/In press - 2018 Jan 1

    Fingerprint

    Cichlids
    gonadotropin-releasing hormone
    gonadotropins
    Gonadotropins
    Gonadotropin-Releasing Hormone
    neurons
    hormones
    Hormones
    brain
    Neurons
    Brain
    fish
    Cichlasoma dimerus
    gonadotropin release
    secretion
    neuropeptides
    innervation
    Neuropeptides
    fluorescent antibody technique

    Keywords

    • Brain
    • Fish
    • GnIH
    • GnRH variants
    • Neurons
    • Pituitary

    ASJC Scopus subject areas

    • Animal Science and Zoology
    • Endocrinology

    Cite this

    Morphological relationship between GnIH and GnRH neurons in the brain of the neotropical cichlid fish Cichlasoma dimerus. / Di Yorio, María P.; Pérez Sirkin, Daniela I.; Muñoz-Cueto, José A.; Delgadin, Tomás H.; Tsutsui, Kazuyoshi; Somoza, Gustavo M.; Vissio, Paula G.

    In: General and Comparative Endocrinology, 01.01.2018.

    Research output: Contribution to journalArticle

    Di Yorio, María P. ; Pérez Sirkin, Daniela I. ; Muñoz-Cueto, José A. ; Delgadin, Tomás H. ; Tsutsui, Kazuyoshi ; Somoza, Gustavo M. ; Vissio, Paula G. / Morphological relationship between GnIH and GnRH neurons in the brain of the neotropical cichlid fish Cichlasoma dimerus. In: General and Comparative Endocrinology. 2018.
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    title = "Morphological relationship between GnIH and GnRH neurons in the brain of the neotropical cichlid fish Cichlasoma dimerus",
    abstract = "Reproduction is regulated by the hypothalamic-pituitary-gonadal axis. The first neuropeptide identified that regulates this function was the decapeptide gonadotropin-releasing hormone (GnRH). Nowadays, in gnatostomates, a number of GnRH variants have been identified and classified into three different types: GnRH1, GnRH2, and GnRH3. Almost 30 years later, a new peptide that inhibits gonadotropin synthesis and secretion was discovered and thus named as gonadotropin-inhibitory hormone (GnIH). In avians and mammals, the interaction and regulation between GnRH and GnIH neurons has been widely studied; however, in other vertebrate groups there is little information about the relationship between these neurons. In previous works, three GnRH variants and a GnIH propeptide were characterized in Cichlasoma dimerus, and it was demonstrated that GnIH inhibited gonadotropins release in this species. Because no innervation was detected at the pituitary level, we speculate that GnIH would inhibit gonadotropins via GnRH. Thus, the aim of the present study was to evaluate the anatomical relationship between neurons expressing GnIH and the three GnRH variants by double labelling confocal immunofluorescence in adults of C. dimerus. Our results showed no apparent contacts between GnIH and GnRH1, fiber to fiber interactions between GnIH and GnRH2, and co-localization of GnIH and GnRH3 variant in neurons of the nucleus olfacto-retinalis. In conclusion, whether GnIH regulates the expression or secretion of GnRH1 in this species, an indirect modulation seems more plausible. Moreover, the present results suggest an interaction between GnIH and GnRH2 systems. Finally, new clues were provided to investigate the role of nucleus olfacto-retinalis cells and putative GnIH and GnRH3 interactions in the modulation of the reproductive network in teleost fish.",
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    AU - Di Yorio, María P.

    AU - Pérez Sirkin, Daniela I.

    AU - Muñoz-Cueto, José A.

    AU - Delgadin, Tomás H.

    AU - Tsutsui, Kazuyoshi

    AU - Somoza, Gustavo M.

    AU - Vissio, Paula G.

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    AB - Reproduction is regulated by the hypothalamic-pituitary-gonadal axis. The first neuropeptide identified that regulates this function was the decapeptide gonadotropin-releasing hormone (GnRH). Nowadays, in gnatostomates, a number of GnRH variants have been identified and classified into three different types: GnRH1, GnRH2, and GnRH3. Almost 30 years later, a new peptide that inhibits gonadotropin synthesis and secretion was discovered and thus named as gonadotropin-inhibitory hormone (GnIH). In avians and mammals, the interaction and regulation between GnRH and GnIH neurons has been widely studied; however, in other vertebrate groups there is little information about the relationship between these neurons. In previous works, three GnRH variants and a GnIH propeptide were characterized in Cichlasoma dimerus, and it was demonstrated that GnIH inhibited gonadotropins release in this species. Because no innervation was detected at the pituitary level, we speculate that GnIH would inhibit gonadotropins via GnRH. Thus, the aim of the present study was to evaluate the anatomical relationship between neurons expressing GnIH and the three GnRH variants by double labelling confocal immunofluorescence in adults of C. dimerus. Our results showed no apparent contacts between GnIH and GnRH1, fiber to fiber interactions between GnIH and GnRH2, and co-localization of GnIH and GnRH3 variant in neurons of the nucleus olfacto-retinalis. In conclusion, whether GnIH regulates the expression or secretion of GnRH1 in this species, an indirect modulation seems more plausible. Moreover, the present results suggest an interaction between GnIH and GnRH2 systems. Finally, new clues were provided to investigate the role of nucleus olfacto-retinalis cells and putative GnIH and GnRH3 interactions in the modulation of the reproductive network in teleost fish.

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