Brown adipose tissue is linked to a distinct thermoregulatory response to mild cold in people

Authors: CHONDRONIKOLA, MARIA - Shriners Hospital For Children; VOLPI, ELENA - University Of Texas Medical Branch; BORSHEIM, ELISABET - Arkansas Children'S Nutrition Research Center (ACNC); CHAO, TONY - Shriners Hospital For Children; PORTER, CRAIG - Shriners Hospital For Children; ANNAMALAI, PALAM - University Of Texas Medical Branch; YFANTI, CHRISTINA - Shriners Hospital For Children; LABBE, SEBASTIEN - Quebec Heart And Lung Research Institute; HURREN, NICHOLAS - University Of Texas Medical Branch; MALAGARIS, IOANNIS - Shriners Hospital For Children; CESANI, FERNARDO - University Of Texas Medical Branch; SIDOSSIS, LABROS - Shriners Hospital For Children

Submitted to: Frontiers in Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2016
Publication Date: 4/19/2016
Citation: Chondronikola, M., Volpi, E., Borsheim, E., Chao, T., Porter, C., Annamalai, P., Yfanti, C., Labbe, S.M., Hurren, N.M., Malagaris, I., Cesani, F., Sidossis, L.S. 2016. Brown adipose tissue is linked to a distinct thermoregulatory response to mild cold in people. Frontiers in Physiology. 7:129. https://doi.org/10.3389/fphys.2016.00129.

Interpretive Summary: It is vital to maintain the core body temperature within a relatively narrow range in the face of large fluctuations in ambient temperature. Deviation from this normal range may indicate the presence of a disease and may be deadly in extreme cases. Brown adipose tissue (BAT) has been shown to be the important to produce heat during non-shivering cold exposure (CE) in mammals, and especially neonates. These properties are attributable to its numerous mitochondria, which contain high amounts of a heat-generating factor called uncoupling protein 1 (UCP1). BAT has recently been identified in adults. We conducted a study to determine if there is a physiologically significant role of BAT in temperature homeostasis outside of the neonatal period in humans. We studied 18 men with significant BAT activity or without/minimal BAT activity during individualized non-shivering CE for 6 h. We found that the presence of BAT is associated with higher tolerance to cold. These results support an important role human BAT in temperature regulation. By studying BAT metabolism in adults, it sheds light on the potential function of this tissue in human infants and adolescents. Furthermore, studies may be conducted to determine BAT's role in metabolism in response to changes in diet, physical activity/exercise, and obesity.

Technical Abstract: Brown adipose tissue (BAT) plays an important role in thermoregulation in rodents. Its role in temperature homeostasis in people is less studied. To this end, we recruited 18 men [8 subjects with no/minimal BAT activity (BAT-) and 10 with pronounced BAT activity (BAT+)]. Each volunteer participated in a 6 h, individualized, non-shivering cold exposure protocol. BAT was quantified using positron emission tomography/computed tomography. Body core and skin temperatures were measured using a telemetric pill and wireless thermistors, respectively. Core body temperature decreased during cold exposure in the BAT- group only (-0.34 degrees C, 95% CI: -0.6 to -0.1, p = 0.03), while the cold-induced change in core temperature was significantly different between BAT+ and BAT- subjects (BAT+ vs. BAT-, 0.43 degrees C, 95% CI: 0.20-0.65, p = 0.0014). BAT volume was associated with the cold-induced change in core temperature (p = 0.01) even after adjustment for age and adiposity. Compared to the BAT- group, BAT+ subjects tolerated a lower ambient temperature (BAT-: 20.6 ± 0.3°C vs. BAT+: 19.8 +/- 0.3 degrees C, p = 0.035) without shivering. The cold-induced change in core temperature (r = 0.79, p = 0.001) and supraclavicular temperature (r = 0.58, p = 0.014) correlated with BAT volume, suggesting that these non-invasive measures can be potentially used as surrogate markers of BAT when other methods to detect BAT are not available or their use is not warranted. These results demonstrate a physiologically significant role for BAT in thermoregulation in people.