The following is a summary of “Brown Adipose Tissue Activation in Humans Increases Plasma Levels of Lipid Mediators,” published in the July 2024 issue of Endocrinology by Walker, et al.

Activating brown adipose tissue (BAT) thermogenesis enhances insulin sensitivity and offers therapeutic benefits for obesity. Recent research indicates that BAT activation elevates lipid mediators that play crucial roles in regulating metabolism and inflammation through both autocrine and endocrine mechanisms. 

For a study, researchers sought to investigate the relationship between 2 different methods of BAT activation—cold exposure and mirabegron treatment—and the associated lipid mediators in humans.

In the study, healthy female participants (n= 14) received daily doses of the β3-adrenergic receptor agonist mirabegron (100 mg) for 28 days. A subgroup of female participants (n= 8) was exposed to cold temperatures (14-16^°C) for 2 hours with a cooling vest before starting mirabegron treatment. The levels of various lipid mediators in plasma were measured using targeted liquid chromatography-tandem mass spectrometry, and their association with different anthropometric and metabolic parameters was analyzed.

Cold exposure activated BAT and led to an acute increase in various lipoxygenase and cyclooxygenase products, including 12-hydroxyeicosapentaenoic acid, 12-hydroxyeicosatetraenoic acid (HETE), 5-HETE, 14-hydroxydocosahexaenoic acid (HDHA), an isomer of maresin 2 (MaR2), 17-HDHA, protectin D1 (PD1), and prostaglandin E2. Similarly, mirabegron treatment increased these lipid mediators acutely, though some mediator levels were reduced with prolonged mirabegron use. Certain lipid mediators, such as the MaR2 isomer, 17-HDHA, 5-HETE, and 15-HETE, showed positive correlations with nonesterified fatty acids and negative correlations with the respiratory quotient. PD1, 15-HETE, and 5-HETE were positively associated with adiponectin levels.

The findings suggested that specific lipid mediators could be used as indicators of BAT activation.

Reference: academic.oup.com/jcem/article-abstract/109/7/1837/7515214