Brown adipose but not white adipose accumulate DHA in cultured cells provided with alpha linolenic acid

Adipose tissue has recently been recognized as a complex endocrine organ which coordinates numerous crucial biological functions including fatty acid metabolism, glucose metabolism, energy homeostasis, and immune function. White adipose tissue (WAT) stores energy, while brown adipose tissue (BAT) dissipates energy while producing heat. Our aim was to compare the fatty acid profiles of undifferentiated and differentiated WAT and BAT per Beige transformed adipocytes provided with alpha linolenic acid. Methods. Murine 3T3 L1 fibroblasts (preWAT) or pre BAT cells were grown in regular media to confluence, and differentiation were then induced to either WAT or BAT. At days 10, 12 and 14, cell were supplemented with 50 μM of albumin bound alpha linolenic acid (ALA). Cells with no ALA supplementation were additional controls. Twenty four hours after supplementation, fatty acid profiles of the cells were analyzed by GC and structural mass spectrometry. Results and  Discussion. ALA supplementation caused an increase in cellular eicosapentaenoic acid (EPA, 20 5n 3) with no change in docosahexaenoic acid (DHA, 22 6n 3) levels in undifferentiated cells. WAT cells accumulated more EPA.  Similarly, BAT cells accumulated EPA, however in contrast differentiated BAT cells also accumulate significant amounts of DHA when compared to undifferentiated preBAT cells. BAT adipocytes are characterized by a vast increase in mitochondria which require highly unsaturated fatty acids. DHA may be required for their function. Conclusion. When provided with ALA, WAT cells accumulate EPA with no change in DHA; BATcells accumulate EPA and DHA. If BAT function similarly in vivo, they may serve as a source of DHA for other tissues. (Authors abstract)