title: Gonadotropin Inhibitory Hormone Down-Regulates the Brain-Pituitary Reproductive Axis of Male European Sea Bass (Dicentrarchus labrax).
abstract: Gonadotropin-inhibitory hormone (GnIH) inhibits gonadotropin synthesis and release from the pituitary of birds and mammals. However, the physiological role of orthologous GnIH peptides on the reproductive axis of fish is still uncertain, and their actions on the main neuroendocrine systems controlling reproduction (i.e., GnRHs, kisspeptins) have received little attention. In a recent study performed in the European sea bass, we cloned a cDNA encoding a precursor polypeptide that contained C-terminal MPMRFamide (sbGnIH-1) and MPQRFamide (sbGnIH-2) peptide sequences, developed a specific antiserum against sbGnIH-2, and characterized its central and pituitary GnIH projections in this species. In this study, we analyzed the effects of intracerebroventricular injection of sbGnIH-1 and sbGnIH-2 on brain and pituitary expression of reproductive hormone genes (gnrh1, gnrh2, gnrh3, kiss1, kiss2, gnih, lhbeta, fshbeta), and their receptors (gnrhr II-1a, gnrhr II-2b, kiss1r, kiss2r, and gnihr) as well as on plasma Fsh and Lh levels. In addition, we determined the effects of GnIH on pituitary somatotropin (Gh) expression. The results obtained revealed the inhibitory role of sbGnIH-2 on brain gnrh2, kiss1, kiss2, kiss1r, gnih, and gnihr transcripts and on pituitary fshbeta, lhbeta, gh, and gnrhr-II-1a expression, whereas sbGnIH-1 only down-regulated brain gnrh1 expression. However, at different doses, central administration of both sbGnIH-1 and sbGnIH-2 decreased Lh plasma levels. Our work represents the first study reporting the effects of centrally administered GnIH in fish and provides evidence of the differential actions of sbGnIH-1 and sbGnIH-2 on the reproductive axis of sea bass, the main inhibitory role being exerted by the sbGnIH-2 peptide.
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), Puerto Real, Spain INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, Puerto Real, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Paullada-Salmerón
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), Puerto Real, Spain INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, Puerto Real, Spain.
authors.forename: Mairi
authors.initials: M
authors.lastname: Cowan
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), Puerto Real, Spain INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, Puerto Real, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Aliaga-Guerrero
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), Puerto Real, Spain INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, Puerto Real, Spain.
authors.forename: Francesca
authors.initials: F
authors.lastname: Morano
authors.affiliation: Institute of Aquaculture of Torre de la Sal, CSIC, Ribera de Cabanes, Castellón, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Zanuy
authors.affiliation: Department of Biology, Faculty of Environmental and Marine Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), Puerto Real, Spain INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, Puerto Real, Spain munoz.cueto@uca.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Muñoz-Cueto
mesh_terms: D000818:Animals; D001492:Bass / Q000502:physiology*; D015870:Gene Expression; D006062:Gonadotropins / Q000097:blood; D007028:Hypothalamic Hormones / Q000502:physiology*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D012098:Reproduction
chemical_list: D006062:Gonadotropins; D007028:Hypothalamic Hormones
keywords: LPXRFamide; fish; gonadotropin-releasing hormone (GnRH); gonadotropins; kisspeptins; perciforms; reproduction; sea bass