Long-chain omega-3 fatty acids regulate bovine whole-body protein metabolism by promoting muscle insulin signalling to the Akt–mTOR–S6K1 pathway and insulin sensitivity |
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Authors: | André e-Anne Gingras,Phillip James White,P. Yvan Chouinard,Pierre Julien,Teresa A. Davis,Luce Dombrowski,Yvon Couture,Pascal Dubreuil,Alexandre Myre,Karen Bergeron,ré Marette, M. Carole Thivierge |
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Affiliation: | Department of Animal Science, Faculty of Food Sciences and Agriculture, Laval University, Québec, QC, G1K 7P4, Canada;Institute of Nutraceuticals and Functional Foods, Faculty of Food Sciences and Agriculture, Laval University, Québec, QC, G1K 7P4, Canada;Lipid Research Center, Laval University Hospital Center (CHUL), Québec, QC, G1V 4G2, Canada;USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA;Facultéde médecine vétérinaire, Universitéde Montréal, St-Hyacinthe, QC, J2S 7C6, Canada |
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Abstract: | The ability of the skeletal musculature to use amino acids to build or renew constitutive proteins is gradually lost with age and this is partly due to a decline in skeletal muscle insulin sensitivity. Since long-chain omega-3 polyunsaturated fatty acids (LC n –3PUFA) from fish oil are known to improve insulin-mediated glucose metabolism in insulin-resistant states, their potential role in regulating insulin-mediated protein metabolism was investigated in this study. Experimental data are based on a switchback design composed of three 5 week experimental periods using six growing steers to compare the effect of a continuous abomasal infusion of LC n –3PUFA-rich menhaden oil with an iso-energetic control oil mixture. Clamp and insulin signalling observations were combined with additional data from a second cohort of six steers. We found that enteral LC n –3PUFA potentiate insulin action by increasing the insulin-stimulated whole-body disposal of amino acids from 152 to 308 μmol kg−1 h−1 ( P = 0.006). The study further showed that in the fed steady-state, chronic adaptation to LC n –3PUFA induces greater activation ( P < 0.05) of the Akt–mTOR–S6K1 signalling pathway. Simultaneously, whole-body total flux of phenylalanine was reduced from 87 to 67 μmol kg−1 h−1 ( P = 0.04) and oxidative metabolism was decreased ( P = 0.05). We conclude that chronic feeding of menhaden oil provides a novel nutritional mean to enhance insulin-sensitive aspects of protein metabolism. |
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