Trans-10, cis-12 conjugated linoleic acid increases fatty acid oxidation in 3T3-L1 preadipocytes

The purpose of this study was to examine the effect of 0-50 mumol/L trans-10, cis-12 conjugated linoleic acid (CLA) and cis-9, trans-11 CLA isomers on lipid and glucose metabolism in cultures of differentiating 3T3-L1 preadipocytes. Specifically, we investigated the effects of 6 d of CLA treatment on the following: 1) C-14-glucose and C-14-oleic acid incorporation and esterification into lipid; 2) C-14-glucose and C-14-fatty acid oxidation; and 3) basal and isoproterenol-stimulated lipolysis. Trans-10, cis-12 CLA supplementation (25 and 50 mumol/L) increased both C-14- glucose and C-14-oleic acid incorporation into the cellular lipid fraction, which was primarily triglyceride (TG), compared with bovine serum albumin (BSA) controls. Although glucose oxidation (C-14-glucose to C-14-CO2) was unaffected by CLA supplementation, oleic acid oxidation (C-14-oleic acid to C-14-CO2) was increased by similar to55% in the presence of 50 mumol/L trans-10, cis-12 CLA compared with BSA controls. In contrast, 50 mumol/L linoleic acid (LA) and cis-9, trans-11 CLA-treated cultures had similar to50% lower CO2 production from C-14-oleic acid compared with control cultures after 6 d of fatty acid exposure. Finally, 50 mumol/L trans-10, cis-12 CLA modestly increased basal, but not isoproterenol-stimulated lipolysis compared with control cultures. Thus, the TG-lowering actions of trans-10, cis-12 CLA in cultures of 3T3-L1 preadipocytes may be via increased fatty acid oxidation, which exceeded its stimulatory effects on glucose and oleic acid incorporation into lipid.