Aims/hypothesis. Brown adipose tissue (BAT) activation increases energy consumption and may have therapeutic potential to combat obesity. Cold exposure is the main physiological stimulus for BAT thermogenesis and the sympathetic nervous system, which innervates BAT, is essential in this process. However cold-induced BAT activation is impaired in obese humans. To explore therapeutic potential it is essential to determine whether pharmacological agents can activate BAT.
Methods. We aimed to determine whether BAT can be activated in lean and obese humans after acute administration of an orally bioavailable sympathomimetic. Nine lean (‘Lean’; BMI, 22±1 kg/m2) and nine obese (‘Obese’; BMI, 36±1 kg/m2) young men were administered 2.5 mg/kg of oral ephedrine (‘Ephedrine’), and on a separate day, a placebo (‘Placebo’), in a randomised, double-blinded, crossover trial. BAT activity was assessed by measuring glucose uptake with 18F-fluorodeoxyglucose (FDG) via positron emission tomography-computed tomography (PET-CT) imaging.
Results. BAT activity was increased by Ephedrine compared with Placebo in Lean but unchanged in Obese. The change in BAT activity after Ephedrine compared to Placebo was negatively correlated with various indices of body fatness.
Conclusions. BAT can be activated via acute, oral administration of the sympathomimetic ephedrine in lean, but not obese humans.