title: TSH restores a summer phenotype in photoinhibited mammals via the RF-amides RFRP3 and kisspeptin.
abstract: In mammals, melatonin is the pivotal messenger synchronizing biological functions, notably reproductive activity, with annual daylength changes. Recently, two major findings clarified melatonin's mode of action. First, melatonin controls the production of thyroid stimulating hormone (TSH) by the pars tuberalis of the adenohypophysis. This TSH regulates local thyroid hormone availability in the mediobasal hypothalamus. Second, the RF-amides kisspeptin and RFRP-3, recently discovered regulators of the gonadotropic axis, are involved in the melatonin control of reproduction. This study aims to establish a mechanistic link between the melatonin-driven TSH and the RF-amide control of reproduction. We treated short-day-adapted male Djungarian and Syrian hamsters with a chronic central infusion of TSH. In both hamster species, the central administration of 5 mIU/d TSH for 4 to 6 wk restored the summer phenotype of both testicular activity and kisspeptin and RFRP expression. Vehicle treated hamsters remain sexually inactive. Furthermore, the TSH treatment increased the body weight of lean short-day-adapted Djungarian hamsters and reduced hypothalamic somatostatin expression to the summer phenotype. In summary, our study demonstrates the pivotal role of melatonin-driven TSH for the seasonal regulation of reproduction and body weight, and uncovers the neuropeptides relaying this signal within the hypothalamus.
authors.affiliation: Département de Neurobiologie des Rythmes, Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique (CNRS) Unité Propres de Recherche (UPR) 3212, Université de Strasbourg, Strasbourg, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Klosen
authors.forename: Marie-Emilie
authors.initials: ME
authors.lastname: Sébert
authors.forename: Kamontip
authors.initials: K
authors.lastname: Rasri
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Laran-Chich
authors.forename: Valérie
authors.initials: V
authors.lastname: Simonneaux
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D006224:Cricetinae; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D057967:Infusions, Intraventricular; D007453:Iodide Peroxidase / Q000235:genetics; D059648:Kisspeptins / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000378:metabolism; D008647:Mesocricetus; D009479:Neuropeptides / Q000378:metabolism*; D017111:Phodopus; D017440:Photoperiod; D011989:Receptors, Thyrotropin / Q000235:genetics; D012621:Seasons; D013004:Somatostatin / Q000378:metabolism; D013045:Species Specificity; D013737:Testis / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D013972:Thyrotropin / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D059648:Kisspeptins; D009479:Neuropeptides; C416987:RFamide peptide; D011989:Receptors, Thyrotropin; D013004:Somatostatin; D013972:Thyrotropin; D007453:Iodide Peroxidase; D008550:Melatonin
keywords: body weight; deiodinase 2; melatonin; reproduction; seasonal rhythms; somatostatin; tancyte