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Dipsogenic genes associated with weight changes during Ironman Triathlons.
Colleen J Saunders1, Liesl de Milander, Tamara Hew-Butler
1Medical Research Council of South Africa, MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Newlands 7725, South Africa.
Human Molecular Genetics
|September 5, 2006
Summary
Certain gene variants, specifically the serotonin transporter-linked polymorphic region (5-HTTLPR) SS genotype and the BDKRB2 +9/+9 genotype, are linked to greater weight loss in endurance athletes. These findings highlight the role of serotonergic pathways and bradykinin in thirst regulation and drinking behavior during intense physical exertion.
Area of Science:
- Physiology
- Genetics
- Endocrinology
Background:
- Thirst regulation involves complex central nervous system pathways, including the renin-angiotensin system, kalikrein-kinin system, and serotonergic pathways.
- Genetic variations in key regulatory genes may influence physiological responses to endurance exercise, such as hydration status and weight changes.
Purpose of the Study:
- To investigate the association between polymorphisms in the ACE, BDKRB2, NOS3, and 5-HTT genes and weight changes in male triathletes during Ironman Triathlons.
- To explore the potential genetic underpinnings of thirst regulation and fluid balance during prolonged strenuous physical activity.
Main Methods:
- Collected pre- and post-race data on serum sodium, body weight, and genotype from 428 Caucasian male triathletes participating in South African Ironman Triathlons.
- Categorized athletes into three groups based on relative weight loss (0-3%, 3-5%, >5%) and analyzed genotype distributions within these groups.
Main Results:
- A significant linear trend was observed for the BDKRB2 +9/+9 genotype and the 5-HTT SS genotype across weight loss groups.
- The >5% weight loss group showed the highest prevalence of the BDKRB2 +9/+9 genotype (P=0.021) and the 5-HTT SS genotype (P=0.016).
- Combined SS 5-HTT and +9/+9 BDKRB2 genotypes were also significantly associated with greater weight loss (P=0.007).
Conclusions:
- The functional SS genotype of the serotonin transporter-linked polymorphic region (5-HTTLPR) and the +9/+9 genotype of the BDKRB2 gene are associated with significant weight loss during Ironman Triathlons.
- These findings suggest a role for serotonergic pathways and bradykinin in modulating thirst and drinking behavior during extreme endurance events.
- Provides further evidence for the dipsogenic effect of circulating bradykinin in physiological contexts.
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