Extracellular Elaidate, a Trans Fatty Acid, Tends to be Incorporated into Triglycerides and Incorporated Elaidate is Released by Lipolysis

Intake of elaidate, an industrially produced trans fatty acid, is associated with the development of cardiovascular disease. Recently, we revealed that persistent exposure to elaidate impairs the insulin responsiveness of adipocytes. Moreover, extracellular elaidate is incorporated into phospholipids and triglycerides and exists mainly as triglycerides in adipocytes. Because fatty acids in adipocytes are not only used as an energy source but also released as cytokines to regulate cellular function and whole-body metabolism, we hypothesized that elaidate is released from adipocytes. Here, we examined the intracellular behavior of elaidate to explain that incorporated elaidate exists mainly as triglycerides, and whether it is released from adipocytes. Extracellular elaidate was incorporated into triglycerides rather than phospholipids, and elaidate incorporated into triglycerides did not decrease during the study period. Under lipolytic stimulation, incorporated elaidate—together with other fatty acids—was released from adipocytes. These results imply that adipocytes act as a reservoir of elaidate.