title: Hormonal changes during 17 days of head-down bed-rest.
abstract: We investigated in six men the impact of 17 days of head-down bed rest (HDBR) on the daily rhythms of the hormones involved in hydroelectrolytic regulation. This HDBR study was designed to mimic a real space flight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of Growth Hormone (GH), Cortisol, 6 Sulfatoxymelatonin, Normetadrenaline (NMN) and Metadrenaline (NM) was determined. A decrease in urinary cortisol excretion during the night of HDBR was noted. For GH, a rhythm was found before and during HDBR. The rhythm of melatonin, evaluated with the urine excretion of 6 Sulfatoxymelatonin (aMT6S), the main hepatic metabolite, persisted throughout the experiment without any modification to the level of phase. A decrease during the night was noted for normetadrenaline urinary derivates, but only during the HDBR.
authors.affiliation: Laboratoire de Physiologie de l'Environnement (GIP exercice), Faculté de Médecine Lyon Grange-Blanche, 8 Avenue Rockefeller, F-69373 Lyon Cedex 08, France. mcustaud@club-internet.fr
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Custaud
authors.forename: Sara B
authors.initials: SB
authors.lastname: Arnaud
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Monk
authors.forename: Bruno
authors.initials: B
authors.lastname: Claustrat
authors.forename: Claude
authors.initials: C
authors.lastname: Gharib
authors.forename: Guillemette
authors.initials: G
authors.lastname: Gauquelin-Koch
mesh_terms: D000328:Adult; D001510:Bed Rest; D001835:Body Weight / Q000502:physiology; D002395:Catecholamines / Q000652:urine; D002940:Circadian Rhythm / Q000502:physiology; D004231:Diuresis / Q000502:physiology; D013006:Growth Hormone / Q000652:urine; D018475:Head-Down Tilt / Q000009:adverse effects / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006728:Hormones / Q000652:urine*; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives* / Q000652:urine; D013026:Space Flight
chemical_list: D002395:Catecholamines; D006728:Hormones; C054513:6-sulfatoxymelatonin; D013006:Growth Hormone; D008550:Melatonin; D006854:Hydrocortisone