title: Effects of pinealectomy on the neuroendocrine reproductive system and locomotor activity in male European sea bass, Dicentrarchus labrax.
abstract: The seasonally changing photoperiod controls the timing of reproduction in most fish species, however, the transduction of this photoperiodic information to the reproductive axis is still unclear. This study explored the potential role of two candidate neuropeptide systems, gonadotropin-inhibitory hormone (Gnih) and kisspeptin, as mediators between the pineal organ (a principle transducer of photoperiodic information) and reproductive axis in male European sea bass, Dicentrarchus labrax. Two seven-day experiments of pinealectomy (Px) were performed, in March (end of reproductive season) and August (resting season). Effects of Px and season on the brain expression of gnih (sbgnih) and its receptor (sbgnihr), kisspeptins (kiss1, kiss2) and their receptors (kissr2, kissr3) and gonadotropin-releasing hormone (gnrh1, gnrh2, gnrh3) and the main brain receptor (gnrhr-II-2b) genes, plasma melatonin levels and locomotor activity rhythms were examined. Results showed that Px reduced night-time plasma melatonin levels. Gene expression analyses demonstrated a sensitivity of the Gnih system to Px in March, with a reduction in sbgnih in the mid-hindbrain, a region with bilateral connections to the pineal organ. In August, kiss2 levels increased in Px animals but not in controls. Significant differences in expression were observed for diencephalic sbgnih, sbgnihr, kissr3 and tegmental gnrh2 between seasons. Recordings of locomotor activity following surgery revealed a change from light-synchronised to free-running rhythmic behavior. Altogether, the Gnih and Kiss2 sensitivity to Px and seasonal differences observed for Gnih and its receptor, Gnrh2, and the receptor for Kiss2 (Kissr3), suggested they could be mediators involved in the relay between environment and seasonal reproduction.
authors.affiliation: Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain. Electronic address: mairi.cowan@uca.es.
authors.forename: Mairi
authors.initials: M
authors.lastname: Cowan
authors.affiliation: Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Paullada-Salmerón
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", E-30100 Murcia, Spain.
authors.forename: José Fernando
authors.initials: JF
authors.lastname: López-Olmeda
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", E-30100 Murcia, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Sánchez-Vázquez
authors.affiliation: Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, Marine Campus of International Excellence (CEIMAR) and Agrifood Campus of International Excellence (ceiA3), E-11510 Puerto Real, Spain; INMAR-CACYTMAR Research Institutes, Puerto Real University Campus, E-11510 Puerto Real, Spain. Electronic address: munoz.cueto@uca.es.
authors.forename: José A
authors.initials: JA
authors.lastname: Muñoz-Cueto
mesh_terms: D000818:Animals; D001492:Bass / Q000235:genetics / Q000502:physiology / Q000601:surgery; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D059648:Kisspeptins / Q000235:genetics*; D008124:Locomotion; D008297:Male; D009479:Neuropeptides / Q000235:genetics*; D009490:Neurosecretory Systems / Q000601:surgery; D010870:Pineal Gland / Q000502:physiology / Q000601:surgery; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives*; D012098:Reproduction / Q000235:genetics* / Q000502:physiology
chemical_list: D059648:Kisspeptins; D009479:Neuropeptides; C448022:gonadotropin-releasing hormone-III; D007987:Gonadotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid
keywords: Behavior; Fish; Gonadotropin-releasing hormone (GnRH); Kisspeptins; LPXRFamide; Pinealectomy; Reproduction; Sea bass