Oleic Acid Promotes Lipid Accumulation in Bovine Adipocytes: The Role of PPARα Activity

Background: Excessive lipid mobilization due to negative energy balance (NEB) in periparturient dairy cows increases their risk for diseases and decreases their productivity. Improving energy intake during the immediate postpartum limits NEB. One way to enhance energy density of the diet is through fatty acid (FA) supplementation. In periparturient cows, oleic acid (OA) limits lipolysis and improves adipose tissue (AT) insulin sensitivity. However, the mechanisms behind OA effect are still unknown. Our objective was to characterize the effect of OA, alone and in combination with palmitic acid (PA), on lipid accumulation, and identify a mechanism of action in bovine adipocytes. Results: Compared with CON, FA treatments had no effect on preadipocyte differentiation (P = 0.65). The treatments 300PA, 200OA, 300OA, 60-40, 50-50, and 40-60 increased lipid accumulation compared with CON (P < 0.0001). At d 7, 300PA and 300OA increased PPARα protein expression compared with CON (P = 0.04). PPARα inhibition decreased triglyceride levels of OA and 60-40 (P<0.05) but not for PA (P=0.26). Pre-adipocytes were isolated from subcutaneous AT explants (Holstein cows) and induced to differentiate into adipocytes. Mature adipocytes were cultured with standard differentiation media (CON) supplemented with PA or OA (100, 200, and 300 µM), and mixtures of PA-OA (60-40, 50-50, and 40-60 at 300 µM) for 4 or 7 d. To evaluate the effect of PPARα signaling, adipocytes were treated with or without a PPARα specific antagonist (GW6471; 10 µM) for 7 d after induction.