PS3-21. What’s at Steak: Effects of Linoleic Acid and Its Trans-10 Biohydrogenation Intermediates on Lipid Metabolism in Intramuscular Bovine Adipocytes.

Abstract Trans-10, cis-12 conjugated linoleic acid (t10,c12 CLA) and trans-10 18:1 (t10-18:1) are the main ruminal biohydrogenation intermediates of linoleic acid (LNA) produced under high-grain feedlot diets. T10,c12 CLA has anti-lipogenic effects, including reducing Δ9-desaturase activity in adipocytes and consequently decreasing lipid synthesis and oleic acid concentration in beef fat. However, the bioactivity of t10-18:1 remains poorly studied despite its much higher concentration in serum and adipose tissues of feedlot cattle. This study aims to elucidate the impact of LNA and its t-10 biohydrogenation intermediates (t10,c12 CLA and t-10 18:1) on lipid metabolism and fatty acid composition in intramuscular bovine adipocytes. Primary intramuscular adipocytes were isolated from three feedlot-finished Angus steers and were then cultured and differentiated followed by treatment with c-10 18:1 (control), t-10 18:1, t10,c12 CLA or linoleic acid (LNA) at 25, 50 or 100uM in maturation media for 9 days before harvest. Gene expression via qPCR and gas chromatography-FID demonstrate t10-18:1, but not c10-18:1, increased (p < 0.05) SCD-1 mRNA expression and the c9 18:1/18:0 desaturation index in a concentration-dependent manner. T10,c12 CLA and LNA decreased (p < 0.05) expression of lipogenic genes, including FAS and ACC1, while CPT1 expression was increased (p < 0.05) with both treatments. Overall, t10,c12 CLA and t10-18:1 had distinct effects on lipogenesis, whereas LNA and t10,c12 CLA showed similar effects on bovine adipocytes.