RESUMEN
Brown adipose tissue (BAT) has been identified as a potential target in the treatment and prevention of obesity and metabolic disease. The precise kinetics of BAT activation and the duration of stimulus required to recruit metabolically active BAT, and its subsequent deactivation, are not well-understood. In this clinical trial, 19 healthy adults (BMI: 23.7 ± 0.7 kg/m2, Age: 31.2 ± 2.8 year, 12 female) underwent three different cooling procedures to stimulate BAT glucose uptake, and active BAT volume was determined using 18F-Fluorodeoxyglucose (FDG) PET/CT imaging. We found that 20 min of pre-injection cooling produces activation similar to the standard 60 min (39.9 mL vs. 44.2 mL, p = 0.52), indicating that BAT activity approaches its peak function soon after the initiation of cooling. Furthermore, upon removal of cold exposure, active BAT volume declines (13.6 mL vs. 44.2 mL, p = 0.002), but the deactivation process persists even hours following cessation of cooling. Thus, the kinetics of human BAT thermogenesis are characterized by a rapid increase soon after cold stimulation but a more gradual decline after rewarming. These characteristics reinforce the feasibility of developing mild, short-duration cold exposure to activate BAT and treat obesity and metabolic disease.
Asunto(s)
Tejido Adiposo Pardo , Hipotermia Inducida , Termogénesis/efectos de la radiación , Tejido Adiposo Pardo/diagnóstico por imagen , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/fisiología , Tejido Adiposo Pardo/efectos de la radiación , Adulto , Frío , Femenino , Fluorodesoxiglucosa F18/administración & dosificación , Fluorodesoxiglucosa F18/metabolismo , Humanos , Cinética , Masculino , Tomografía Computarizada por Tomografía de Emisión de PositronesRESUMEN
OBJECTIVE: We hypothesized that the hypoxia-inducible factor (HIF) 1α in vascular smooth muscle contributes to the development of atherosclerosis, and links intravascular pressure to this process. APPROACH AND RESULTS: Transverse aortic constriction was used to create high-pressure vascular segments in control, apolipoprotein E (ApoE)(-/-), smooth muscle-HIF1α(-/-), and ApoE(-/-)×smooth muscle-HIF1α(-/-) double-knockout mice. Transverse aortic constriction selectively induced atherosclerosis in high-pressure vascular segments in young ApoE(-/-) mice on normal chow, including coronary plaques within 1 month. Concomitant deletion of HIF1α from smooth muscle significantly reduced vascular inflammation, and attenuated atherosclerosis. CONCLUSIONS: HIF1α in vascular smooth muscle plays an important role in the pathogenesis of atherosclerosis, and may provide a mechanistic link between blood pressure, vascular inflammation, and lipid deposition.
