Effects of linoleic acid and its trans-10 biohydrogenation intermediates (trans-10, cis-12 conjugated linoleic acid and trans-10 18:1) on lipogenic gene expression and Δ9-desaturation indices in bovine intramuscular adipocytes.

Trans-10, cis-12 conjugated linoleic acid (t10, c12-CLA) and trans-10 18:1 (t10-18:1) are major ruminal biohydrogenation intermediates of linoleic acid (LNA) under high-grain diets. T10, c12-CLA has been shown to reduce Δ9-desaturase (SCD1) activity and the cis-monounsaturated to saturated fatty acid ratio (cisMUFA/SFA) in beef fat. However, the bioactivities of LNA and t10-18:1 remain poorly understood. This study evaluated LNA and its trans-10 intermediates in bovine intramuscular adipocytes. Intramuscular preadipocytes were isolated from three feedlot-finished Angus steers and differentiated for two experiments. Experiment 1 evaluated dose-response effects of t10-18:1, t10, c12-CLA, and LNA at 0, 25, 50, and 100 μM. Experiment 2 compared LNA, t10-18:1, t10, c12-CLA, and c10-18:1 at 50 μM with the bovine serum albumin (BSA) control. Lipid accumulation, gene expression, and fatty acid composition were analyzed by Nile Red staining, qPCR, and gas chromatography, respectively. Data were analyzed using the MIXED procedure of SAS. Lipid accumulation was unaffected by treatment in either experiment. T10-18:1 dose-dependently increased SCD1 expression and c9-18:1/18:0 in Experiment 1 (P < 0.05), with both greater than the BSA control and other treatments in Experiment 2 (P < 0.05). LNA dose-dependently reduced SCD1 expression, cisMUFA/SFA, c9-16:1/16:0, and c9-18:1/18:0 in Experiment 1, with all four lower than the BSA control in Experiment 2 (P < 0.05). T10, c12-CLA reduced SCD1 expression in both experiments and cisMUFA/SFA in Experiment 1 (P < 0.05) but did not alter c9-16:1/16:0 or c9-18:1/18:0 in either experiment. These findings demonstrate distinct effects of LNA and its trans-10 biohydrogenation intermediates on lipogenic gene expression and Δ9-desaturation in bovine intramuscular adipocytes.