title: In the Heat of the Night: Thermo-TRPV Channels in the Salmonid Pineal Photoreceptors and Modulation of Melatonin Secretion.
abstract: Photoperiod plays an essential role in the synchronization of metabolism, physiology, and behavior to the cyclic variations of the environment. In vertebrates, information is relayed by the pineal cells and translated into the nocturnal production of melatonin. The duration of this signal corresponds to the duration of the night. In fish, the pinealocytes are true photoreceptors in which the amplitude of the nocturnal surge is modulated by temperature in a species-dependent manner. Thus, the daily and annual variations in the amplitude and duration of the nocturnal melatonin signal provide information on daily and calendar time. Both light and temperature act on the activity of the penultimate enzyme in the melatonin biosynthesis pathway, the arylalkylamine N-acetyltransferase (serotonin → N-acetylserotonin). Although the mechanisms of the light/dark regulation of melatonin secretion are quite well understood, those of temperature remain unelucidated. More generally, the mechanisms of thermoreception are unknown in ectotherms. Here we provide the first evidence that two thermotransient receptor potential (TRP) channels, TRPV1 and TRPV4, are expressed in the pineal photoreceptor cells of a teleost fish, in which they modulate melatonin secretion in vitro. The effects are temperature dependent, at least for TRPV1. Our data support the idea that the pineal of fish is involved in thermoregulation and that the pineal photoreceptors are also thermoreceptors. In other nervous and nonnervous tissues, TRPV1 and TRPV4 display a ubiquitous but quantitatively variable distribution. These results are a fundamental step in the elucidation of the mechanisms of temperature transduction in fish.
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Laura Gabriela
authors.initials: LG
authors.lastname: Nisembaum
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Laurence
authors.initials: L
authors.lastname: Besseau
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Charles-Hubert
authors.initials: CH
authors.lastname: Paulin
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Alice
authors.initials: A
authors.lastname: Charpantier
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Patrick
authors.initials: P
authors.lastname: Martin
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Elodie
authors.initials: E
authors.lastname: Magnanou
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Michael
authors.initials: M
authors.lastname: Fuentès
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Maria-Jesus
authors.initials: MJ
authors.lastname: Delgado
authors.affiliation: Sorbonne Universités, Université Pierre et Marie Curie, Paris 06 (L.B., C.-H.P., A.C.), Centre National de la Recherche Scientifique (L.G.N., E.M., M.F., J.F.), Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, F-66650 Banyuls sur Mer, France; Conservatoire National du Saumon Sauvage (P.M.), F-43300 Chanteuges, France; and Universidad Complutense de Madrid (L.G.N., M.J.D.) E-28040 Madrid, Spain.
authors.forename: Jack
authors.initials: J
authors.lastname: Falcón
mesh_terms: D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000378:metabolism; D066298:In Vitro Techniques; D008550:Melatonin / Q000378:metabolism*; D017686:Oncorhynchus mykiss; D009924:Organ Culture Techniques; D017440:Photoperiod; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism*; D010870:Pineal Gland / Q000166:cytology / Q000378:metabolism*; D012487:Salmonidae; D050916:TRPV Cation Channels / Q000378:metabolism*; D013696:Temperature; D013823:Thermoreceptors / Q000378:metabolism*
chemical_list: D050916:TRPV Cation Channels; D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin