trans-10,cis-12-conjugated linoleic acid reduces leptin secretion from 3T3-L1 adipocytes

The trans10,cis12 (t10c12) isomer of conjugated linoleic acid (CLA) has bee n shown to inhibit heparin-releasable lipoprotein lipase activity, reduce l ipid stores in cultured 3T3-L1 adipocytes, and, when fed to mice, reduce bo dy fat gain. We now report that t10c12 CLA significantly reduced leptin sec retion from cultured 3T3-L1 adipocytes, and reduced leptin mRNA levels with in the cells. Similar effects were produced by conjugated nonadecadienoic a cid (a 19-carbon CLA cognate that is more effective than CLA in reducing bo dy fat gain in mice), the lipoxygenase inhibitor nordihydroguaiaretic acid (which is synergistic with CLA in reducing body fat gain in mice), and cigl itazone (TZD, a PPAR gamma agonist). Feeding mice diet supplemented with 0. 5% t10c12 CLA for 4 weeks significantly reduced body fat gain, serum leptin levels and adipocyte leptin mRNA expression, without affecting feed intake or body weight. These data provide new insights into apparent mechanistic similarities among t10c12 CLA, CNA NDGA, and TZD. (C) 2001 Academic Press.