The functional role of brown adipose tissue in whole‐body lipid metabolism in humans (1160.3)

Abstract

Despite intense scientific interest regarding the role of human brown adipose tissue (BAT) in substrate metabolism, its role in whole‐body lipid metabolism remains unclear. To address this issue, we studied otherwise matched men with high (HBAT, n=7) and low (LBAT: n=5) BAT volume (69±18 mL vs. 4±2 mL, p<0.05) under cold exposure (CE) and thermoneutral (TN) conditions using positron emission tomography‐computed tomography, stable isotope infusions, and indirect calorimetry. For HBAT, but not LBAT participants, plasma free fatty acid concentrations (TN: 0.36±0.01mmol/L vs. CE: 0.63±0.01mmol/L, p<0.05), plasma glycerol concentrations (TN: 0.05±0.01 mmol/L vs. CE: 0.09±0.01 mmol/L, p<0.05), lipolysis (TN: 2.2±0.3 μmol/kg/min vs. CE: 5.9±0.6μmol/kg/min, p<0.05), and plasma free fatty acid oxidation (TN: 2.7±0.6 μmol/kg/min vs. CE: 5.9±1.0 μmol/kg/min, p<0.05) were higher under CE conditions than TN conditions. Moreover, during CE, plasma small LDL and large HDL particles increased more in the HBAT group than in the LBAT group (p<0.05). Finally, the HBAT group tended to have decreased plasma triglyceride concentrations the day after CE (‐33.4±11.4 mg/dl, p=0.06), whereas LBAT subjects showed no significant change. These novel findings demonstrate a functional role of BAT in human lipid metabolism.Grant Funding Source: : CTSA UL1TR000071, Pepper Center Pilot Grant, Sealy Center on Aging, Shriners Hospitals