title: Is the kisspeptin system involved in responses to food restriction in order to preserve reproduction in pubertal male sea bass (Dicentrarchus labrax)?
abstract: Previous works on European sea bass have determined that long-term exposure to restrictive feeding diets alters the rhythms of some reproductive/metabolic hormones, delaying maturation and increasing apoptosis during gametogenesis. However, exactly how these diets affect key genes and hormones on the brain-pituitary-gonad (BPG) axis to trigger puberty is still largely unknown. We may hypothesize that all these signals could be integrated, at least in part, by the kisspeptin system. In order to capture a glimpse of these regulatory mechanisms, kiss1 and kiss2 mRNA expression levels and those of their kiss receptors (kiss1r, kiss2r) were analyzed in different areas of the brain and in the pituitary of pubertal male sea bass during gametogenesis. Furthermore, other reproductive hormones and factors as well as the percentage of males showing full spermiation were also analyzed. Treated fish fed maintenance diets provided evidence of overexpression of the kisspeptin system in the main hypophysiotropic regions of the brain throughout the entire sexual cycle. Conversely, Gnrh1 and gonadotropin pituitary content and plasma sexual steroid levels were downregulated, except for Fsh levels, which were shown to increase during spermiation. Treated fish exhibited lower rates of spermiation as compared to control group and a delay in its accomplishment. These results demonstrate how the kisspeptin system and plasma Fsh levels are differentially affected by maintenance diets, causing a retardation, but not a full blockage of the reproductive process in the teleost fish European sea bass. This suggests that a hormonal adaptive strategy may be operating in order to preserve reproductive function in this species.
authors.affiliation: Instituto de Acuicultura Torre de la Sal (IATS), Consejo Superior de Investigaciones Científicas (CSIC), 12595 Ribera de Cabanes S/N, Castellón, Spain.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Escobar
authors.affiliation: Instituto de Acuicultura Torre de la Sal (IATS), Consejo Superior de Investigaciones Científicas (CSIC), 12595 Ribera de Cabanes S/N, Castellón, Spain. Electronic address: afelip@iats.csic.es.
authors.forename: Alicia
authors.initials: A
authors.lastname: Felip
authors.affiliation: Instituto de Acuicultura Torre de la Sal (IATS), Consejo Superior de Investigaciones Científicas (CSIC), 12595 Ribera de Cabanes S/N, Castellón, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Zanuy
authors.affiliation: Instituto de Acuicultura Torre de la Sal (IATS), Consejo Superior de Investigaciones Científicas (CSIC), 12595 Ribera de Cabanes S/N, Castellón, Spain. Electronic address: m.carrillo@csic.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Carrillo
mesh_terms: D000818:Animals; D001492:Bass / Q000235:genetics / Q000502:physiology*; D029941:Fish Proteins / Q000235:genetics / Q000502:physiology*; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism; D005502:Food; D015870:Gene Expression; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D006062:Gonadotropins / Q000097:blood / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D059648:Kisspeptins / Q000235:genetics / Q000502:physiology*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008636:Mesencephalon / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D016548:Prosencephalon / Q000378:metabolism; D011962:Receptors, FSH / Q000235:genetics / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000502:physiology; D011974:Receptors, LH / Q000235:genetics / Q000502:physiology; D012098:Reproduction / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012621:Seasons; D012741:Sexual Maturation / Q000235:genetics / Q000502:physiology*; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology
chemical_list: D029941:Fish Proteins; D006062:Gonadotropins; D059648:Kisspeptins; D011962:Receptors, FSH; D043562:Receptors, G-Protein-Coupled; D011974:Receptors, LH; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: Brain; Food restriction; Kisspeptins; Reproductive hormones; Sexual maturation; Teleost