title: Brown fat activation mediates cold-induced thermogenesis in adult humans in response to a mild decrease in ambient temperature.
abstract: BACKGROUND
  The contribution of brown adipose tissue (BAT) to the energy balance in humans exposed to sustainable cold has not been completely established, partially because of measurement limitations of both BAT activity and energy expenditure (EE).
  
  
  OBJECTIVE
  The objective of the study was to characterize the role of BAT activation in cold-induced thermogenesis (CIT).
  
  
  METHODS
  This study was a single-blind, randomized crossover intervention.
  
  
  METHODS
  The study was conducted at the National Institutes of Health Clinical Center.
  
  
  METHODS
  Thirty-one healthy volunteers participated in the study.
  
  
  METHODS
  The intervention included mild cold exposure.
  
  
  RESULTS
  CIT and BAT activation were the main outcomes in this study.
  
  
  METHODS
  Overnight EE measurement by whole-room indirect calorimeter at 24 °C or 19 °C was followed by 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography (PET) scan. After 36 hours, volunteers crossed over to the alternate study temperature under identical conditions. BAT activity was measured in a 3-dimensional region of interest in the upper torso by comparing the uptake at the two temperatures.
  
  
  RESULTS
  Twenty-four volunteers (14 males, 10 females) had a complete data set. When compared with 24 °C, exposure at 19 °C resulted in increased EE (5.3 ± 5.9%, P < .001), indicating CIT response and mean BAT activity (10.5 ± 11.1%, P < .001). Multiple regression analysis indicated that a difference in BAT activity (P < .001), age (P = .01), and gender (P = .037) were independent contributors to individual variability of CIT.
  
  
  CONCLUSIONS
  A small reduction in ambient temperature, within the range of climate-controlled buildings, is sufficient to increase human BAT activity, which correlates with individual CIT response. This study uncovers for the first time a spectrum of BAT activation among healthy adults during mild cold exposure not previously recognized by conventional PET and PET-computed tomography methods. The enhancement of cold-induced BAT stimulation may represent a novel environmental strategy in obesity treatment.
authors.affiliation: Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892-1613, USA.
authors.forename: Kong Y
authors.initials: KY
authors.lastname: Chen
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Brychta
authors.forename: Joyce D
authors.initials: JD
authors.lastname: Linderman
authors.forename: Sheila
authors.initials: S
authors.lastname: Smith
authors.forename: Amber
authors.initials: A
authors.lastname: Courville
authors.forename: William
authors.initials: W
authors.lastname: Dieckmann
authors.forename: Peter
authors.initials: P
authors.lastname: Herscovitch
authors.forename: Corina M
authors.initials: CM
authors.lastname: Millo
authors.forename: Alan
authors.initials: A
authors.lastname: Remaley
authors.forename: Paul
authors.initials: P
authors.lastname: Lee
authors.forename: Francesco S
authors.initials: FS
authors.lastname: Celi
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging / Q000378:metabolism*; D050154:Adiposity; D000328:Adult; D000367:Age Factors; D000389:Air Conditioning; D002153:Calorimetry, Indirect; D003080:Cold Temperature; D018592:Cross-Over Studies; D004734:Energy Metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012727:Sex Characteristics; D016037:Single-Blind Method; D022722:Thermogenesis; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18