MRI Reveals Human Brown Adipose Tissue Is Rapidly Activated in Response to Cold.

ABSTRACT:

Context

In rodents, cold exposure induces the activation of brown adipose tissue (BAT) and the induction of intracellular triacylglycerol (TAG) lipolysis. However, in humans, the kinetics of supraclavicular (SCV) BAT activation and the potential importance of TAG stores remain poorly defined.

Objective

To determine the time course of BAT activation and changes in intracellular TAG using MRI assessment of the SCV (i.e., BAT depot) and fat in the posterior neck region (i.e., non-BAT).

Design

Cross-sectional.

Setting

Clinical research center.

Patients or other participants

Twelve healthy male volunteers aged 18 to 29 years [body mass index = 24.7 ± 2.8 kg/m² and body fat percentage = 25.0% ± 7.4% (both, mean ± SD)].

Interventions

Standardized whole-body cold exposure (180 minutes at 18°C) and immediate rewarming (30 minutes at 32°C).

Main outcome measures

Proton density fat fraction (PDFF) and T2* of the SCV and posterior neck fat pads. Acquisitions occurred at 5- to 15-minute intervals during cooling and subsequent warming.

Results

SCV PDFF declined significantly after only 10 minutes of cold exposure [-1.6% (SE: 0.44%; P = 0.007)] and continued to decline until 35 minutes, after which time it remained stable until 180 minutes. A similar time course was also observed for SCV T2*. In the posterior neck fat (non-BAT), there were no cold-induced changes in PDFF or T2*. Rewarming did not result in a change in SCV PDFF or T2*.

Conclusions

The rapid cold-induced decline in SCV PDFF suggests that in humans BAT is activated quickly in response to cold and that TAG is a primary substrate.

SUBMITTER: Oreskovich SM 

PROVIDER: S-EPMC6855213 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature