Activation of human brown adipocytes alters the plasma fatty acid profile.

Introduction: Even though brown adipose tissue (BAT) has recently been identified as a possible target for combating obesity and type 2 diabetes, neither the mechanisms of its activation nor its relationships to clinical parameters are clearly defined. Metabolomics enables the simultaneous analysis of multiple classes of compounds, thus seems to be a perfect tool to study this topic. This study aimed to explore alterations during cold exposure (CE) associated with the activation of BAT. Materials and methods: Twenty-five healthy male adults underwent 2 hours of CE followed by PET-MRI. Afterwards, they were divided into two groups, depending on BAT presence (BATpos or BATneg). The levels of metabolites were measured in plasma samples at three time points: before, after one, and 2 hours of CE, using a standard gas chromatography-mass spectrometry (GC-MS) method for metabolite profiling. Results: In the BATpos group, the levels of linoleic, oleic, and palmitic acids were significantly increased after 120 min of CE compared to the baseline. These changes were absent in the BATneg group. When comparing the BATpos and BATneg groups, we observed that the BATpos group had significantly lower baseline level of succinic acid. After 60 min of CE, the BATpos group showed significantly increased levels of linoleic, oleic and trans-13-octadecenoic acid. The differences in oleic acid persisted for another hour. Conclusion: Between-group differences in the level of fatty acids during CE, along with the BATpos group-specific alterations during CE, suggest that the activation of BAT affects lipid metabolism.