Induction of peroxisomal proliferator-activated receptor γ and peroxisomal proliferator-activated receptor γ coactivator 1 by unsaturated fatty acids, retinoic acid, and carotenoids in preadipocytes obtained from bovine white adipose tissue

The importance of dietary fat components, such as fatty acids, in the expression of multiple genes is clear. In the case of beef cattle, fat in the form of fatty acids (saturated or unsaturated), vitamin A (mainly retinoic acid), or carotenoids (beta-carotene and lutein) is obtained from dietary feed or pasture. The aim of this work was to study the effect of fatty acids (phytanic and pristanic acids), vitamin A (all-trans and 9-cis retinoic acid), and carotenoids (beta-carotene and lutein) on the expression of PPAR. and its coactivator PGC-1 alpha during differentiation of bovine white adipose tissue. Samples were collected at slaughter from subcutaneous adipose tissue and processed in a solution containing type II collagenase for 2 h at 37 degrees C. Cells were resuspended in basal medium, Dulbecco's modified Eagle's medium containing 5% fetal bovine serum, plated on 24-well culture plates at a density of 1 x 10(4) cells/cm(2), and incubated at 37 degrees C in a 5% CO2 atmosphere. Preadipocyte differentiation after reaching confluence was induced by various treatments: rosiglitazone (20 mu M); unsaturated fatty acids: phytanic acid (25, 50, 100 mu M) and pristanic acid (25, 50, 100 mu M); retinoids: 9-cis retinoic acid (0.5, 0.75, 1 mu M) and all-trans retinoic acid (0.5, 0.75, 1 mu M); and carotenoids: beta-carotene (10, 20, 30 mu M) and lutein (10, 20, 30 mu M). Expression of PPAR. and PGC-1 alpha was measured in differentiated cells. Phytanic acid, all-trans retinoic acid, and 9-cis retinoic acid were the best activators of PPAR. expression, and the combination of 9-cis and all-trans retinoic acid was the best activator of PGC-1 alpha expression (P < 0.05). Therefore, these are powerful agents for the promotion of bovine adipogenesis and constitute promising compounds to be used in bovine fattening.