title: Brown adipose tissue oxidative metabolism contributes to energy expenditure during acute cold exposure in humans.
abstract: Brown adipose tissue (BAT) is vital for proper thermogenesis during cold exposure in rodents, but until recently its presence in adult humans and its contribution to human metabolism were thought to be minimal or insignificant. Recent studies using PET with 18F-fluorodeoxyglucose (18FDG) have shown the presence of BAT in adult humans. However, whether BAT contributes to cold-induced nonshivering thermogenesis in humans has not been proven. Using PET with 11C-acetate, 18FDG, and 18F-fluoro-thiaheptadecanoic acid (18FTHA), a fatty acid tracer, we have quantified BAT oxidative metabolism and glucose and nonesterified fatty acid (NEFA) turnover in 6 healthy men under controlled cold exposure conditions. All subjects displayed substantial NEFA and glucose uptake upon cold exposure. Furthermore, we demonstrated cold-induced activation of oxidative metabolism in BAT, but not in adjoining skeletal muscles and subcutaneous adipose tissue. This activation was associated with an increase in total energy expenditure. We found an inverse relationship between BAT activity and shivering. We also observed an increase in BAT radio density upon cold exposure, indicating reduced BAT triglyceride content. In sum, our study provides evidence that BAT acts as a nonshivering thermogenesis effector in humans.
authors.affiliation: Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Ouellet
authors.forename: Sébastien M
authors.initials: SM
authors.lastname: Labbé
authors.forename: Denis P
authors.initials: DP
authors.lastname: Blondin
authors.forename: Serge
authors.initials: S
authors.lastname: Phoenix
authors.forename: Brigitte
authors.initials: B
authors.lastname: Guérin
authors.forename: François
authors.initials: F
authors.lastname: Haman
authors.forename: Eric E
authors.initials: EE
authors.lastname: Turcotte
authors.forename: Denis
authors.initials: D
authors.lastname: Richard
authors.forename: André C
authors.initials: AC
authors.lastname: Carpentier
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000328:Adult; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology; D003080:Cold Temperature; D004734:Energy Metabolism / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D022722:Thermogenesis / Q000502:physiology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D019788:Fluorodeoxyglucose F18