title: Interactions between temperature and human leptin physiology in vivo and in vitro.
abstract: To investigate the possibility that environmental temperature may exert physiologically significant direct, local effects on subcutaneous adipose tissue temperatures, and its secretion of leptin, we exposed healthy males ( n=12) to repeated cold-water immersion (study 1), and also incubated surgically removed human subcutaneous adipose tissue samples ( n=7) at 27 degrees, 32 degrees and 37 degrees C (study 2). In vivo immersions were conducted over 15 days (60-90 min at 18 degrees C). Regional body temperatures and plasma leptin concentrations were measured before and during immersion. Acute cold exposure suppressed plasma leptin concentration (25 min: -14%, 60 min: -22%, P=0.0001), whilst repeated cold-water immersion was associated with an increase of plasma leptin concentration relative to test day 1 (+19% day 8, +13% day 15, overall P=0.03). Leptin secretion in vitro decreased 3.7-fold as the incubation temperature decreased from 37 degrees to 27 degrees C ( P=0.001). In a compartmental model of leptin turnover in vivo, the measured (local) temperature effect on leptin secretion in vitro was more than able to account for the observed cold-induced decrease in leptin concentration in vivo. We therefore conclude that acute and repeated cold-water immersions have separate and opposing effects on circulating leptin concentrations in humans. Under our experimental conditions, the local effects of reduced subcutaneous adipose tissue temperature may be a more important contributor to the acute effects observed in vivo, than the sympathetically mediated suppression of leptin secretion.
authors.affiliation: Metabolic Research Centre and Department of Biomedical Science, University of Wollongong, Wollongong, New South Wales, Australia 2522.
authors.forename: Annerieke
authors.initials: A
authors.lastname: Zeyl
authors.forename: Jodie M
authors.initials: JM
authors.lastname: Stocks
authors.forename: Nigel A S
authors.initials: NA
authors.lastname: Taylor
authors.forename: Arthur B
authors.initials: AB
authors.lastname: Jenkins
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000222:Adaptation, Physiological; D000273:Adipose Tissue / Q000378:metabolism / Q000502:physiology*; D000328:Adult; D000465:Algorithms; D001823:Body Composition / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D003080:Cold Temperature; D004734:Energy Metabolism / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007101:Immersion; D020738:Leptin / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D012881:Skin Temperature / Q000502:physiology; D013696:Temperature
chemical_list: D020738:Leptin