Mapping of human brown adipose tissue in lean and obese young men

Abstract

Human brown adipose tissue (BAT) can be activated to increase glucose uptake and energy expenditure, making it a potential target for treating obesity and metabolic disease. Data on the functional and anatomic characteristics of BAT are limited, however. In 20 healthy young men [12 lean, mean body mass index (BMI) 23.2 ± 1.9 kg/m 2 ; 8 obese, BMI 34.8 ± 3.3 kg/m 2 ] after 5 h of tolerable cold exposure, we measured BAT volume and activity by 18 F-labeled fluorodeoxyglucose positron emission tomography/computerized tomography (PET/CT). Obese men had less activated BAT than lean men (mean, 130 vs. 334 mL) but more fat in BAT-containing depots (mean, 1,646 vs. 855 mL) with a wide range (0.1-71%) in the ratio of activated BAT to inactive fat between individuals. Six anatomic regions had activated BAT-cervical, supraclavicular, axillary, mediastinal, paraspinal, and abdominal-with 67 ± 20% of all activated BAT concentrated in a continuous fascial layer comprising the first three depots in the upper torso. These nonsubcutaneous fat depots amounted to 1.5% of total body mass (4.3% of total fat mass), and up to 90% of each depot could be activated BAT. The amount and activity of BAT was significantly influenced by region of interest selection methods, PET threshold criteria, and PET resolutions. The present study suggests that active BAT can be found in specific adipose depots in adult humans, but less than one-half of the fat in these depots is stimulated by acute cold exposure, demonstrating a previously underappreciated thermogenic potential.brown fat | PET/CT | obesity | metabolism

Butyrate reduces appetite and activates brown adipose tissue via the gut-brain neural circuit

“…Although the relative volume of BAT in humans may be limited compared with skeletal muscle, the uptake of fatty acids per gram tissue by BAT exceeds that by skeletal muscle by >10-fold (figure 3F). Also, a recent paper redefined whole-body BAT distribution in humans and concluded that its metabolic capacity is substantially higher than usually reported 40. The effects of butyrate on fatty acid uptake and oxidation by BAT we observe in mice may thus well be relevant for humans.…”

Genetic Markers of Brown Adipose Tissue Identity and In Vitro Brown Adipose Tissue Activity in Humans

“…It has been reported that higher human in vivo BAT activity changes metabolism through increased energy expenditure . However, the current topic of debate questions whether we fully grasp the complete thermogenic potential of active human BAT . The finding that ZIC1 was positively associated with age and BMI and negatively associated with BAT activity is interesting because, to the best of our knowledge, no links have been established between BAT activity and ZIC1.…”

Obesity Tissue: Composition, Energy Expenditure, and Energy Content in Adult Humans

“…Another limitation of the current study is that not all fat is in adipose tissue, and we were unable to adjust our organ mass estimates for nonadipose intracellular triglyceride content . Similarly, we did not build brown fat, a potential source of thermogenesis, into our models . Lastly, we contrasted obesity‐tissue features in men to those observed in our sample of women.…”