title: Dipsogenic genes associated with weight changes during Ironman Triathlons.
abstract: Thirst is regulated by a complex interaction of signalling pathways within the central nervous system, including components of the renin-angiotensin and kalikrein kinin systems, as well as the serotonergic pathways. The aim of this study was to determine whether there were any associations between polymorphisms within the ACE, BDKRB2, NOS3 and/or 5-HTT genes with weight changes during the 2000 and 2001 226 km South African Ironman Triathlons. Pre- and post-race serum [Na(+)] and body weights, as well as genotype data, were collected from 428 (61.1%) Caucasian male triathletes who were divided into three groups according to their relative weight loss during the triathlon (0-3, 3-5 and >5%). There was a significant linear trend for the distribution of both the BDKRB2 +9/+9 genotype and the 5-HTT SS genotype between the three weight loss groups, with the >5% group having the highest percentage of athletes with the +9/+9 genotype (chi(2)=5.3, P=0.021) and the highest percentage of athletes with the SS genotype (chi(2)=5.8, P=0.016). Likewise, the >5% group had the highest percentage of athletes with the combined SS 5-HTT and/or +9/+9 BDKRB2 genotypes (chi(2)=7.4, P=0.007). In conclusion, the functional SS genotype of the serotonin transporter-linked polymorphic region (5-HTTLPR) within the 5-HTT gene and the functional +9/+9 genotype of the BDKBR2 gene were associated with larger weight losses during the Ironman Triathlons. These findings suggest the involvement of the serotonergic pathways in the control of thirst and drinking behaviour and provide further evidence for the dipsogenic effect of circulating bradykinin.
authors.affiliation: Medical Research Council of South Africa, MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Newlands 7725, South Africa.
authors.forename: Colleen J
authors.initials: CJ
authors.lastname: Saunders
authors.forename: Liesl
authors.initials: L
authors.lastname: de Milander
authors.forename: Tamara
authors.initials: T
authors.lastname: Hew-Butler
authors.forename: Stavroulla L
authors.initials: SL
authors.lastname: Xenophontos
authors.forename: Marios A
authors.initials: MA
authors.lastname: Cariolou
authors.forename: Lakis C
authors.initials: LC
authors.lastname: Anastassiades
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Noakes
authors.forename: Malcolm
authors.initials: M
authors.lastname: Collins
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology; D004327:Drinking Behavior / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D052250:Nitric Oxide Synthase Type III / Q000235:genetics; D007703:Peptidyl-Dipeptidase A / Q000235:genetics; D011110:Polymorphism, Genetic; D043782:Receptor, Bradykinin B2 / Q000235:genetics*; D012420:Running / Q000502:physiology; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D013019:South Africa; D013177:Sports / Q000502:physiology*; D013550:Swimming / Q000502:physiology; D013894:Thirst / Q000502:physiology*; D015431:Weight Loss
chemical_list: D043782:Receptor, Bradykinin B2; D050486:Serotonin Plasma Membrane Transport Proteins; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C488034:ACE protein, human; D007703:Peptidyl-Dipeptidase A