title: 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.
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 (LCn-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 LCn-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 LCn-3PUFA potentiate insulin action by increasing the insulin-stimulated whole-body disposal of amino acids from 152 to 308 micromol kg(-1) h(-1) (P=0.006). The study further showed that in the fed steady-state, chronic adaptation to LCn-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 micromol 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.
authors.affiliation: Department of animal science, Faculty of Food Sciences and Agriculture, Laval University, Quebec, QC G1K 7P4 Canada.
authors.forename: Andrée-Anne
authors.initials: AA
authors.lastname: Gingras
authors.forename: Phillip James
authors.initials: PJ
authors.lastname: White
authors.forename: P Yvan
authors.initials: PY
authors.lastname: Chouinard
authors.forename: Pierre
authors.initials: P
authors.lastname: Julien
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Davis
authors.forename: Luce
authors.initials: L
authors.lastname: Dombrowski
authors.forename: Yvon
authors.initials: Y
authors.lastname: Couture
authors.forename: Pascal
authors.initials: P
authors.lastname: Dubreuil
authors.forename: Alexandre
authors.initials: A
authors.lastname: Myre
authors.forename: Karen
authors.initials: K
authors.lastname: Bergeron
authors.forename: André
authors.initials: A
authors.lastname: Marette
authors.forename: M Carole
authors.initials: MC
authors.lastname: Thivierge
mesh_terms: D000818:Animals; D001706:Biopsy; D002247:Carbon Isotopes; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D004044:Dietary Proteins / Q000493:pharmacokinetics*; D004734:Energy Metabolism / Q000502:physiology*; D015525:Fatty Acids, Omega-3 / Q000493:pharmacokinetics*; D005395:Fish Oils / Q000493:pharmacokinetics; D015309:Glucose Clamp Technique; D006128:Growth / Q000187:drug effects / Q000502:physiology; D006946:Hyperinsulinism / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D010649:Phenylalanine / Q000097:blood / Q000493:pharmacokinetics; D010743:Phospholipids / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012044:Regression Analysis; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases
chemical_list: D002247:Carbon Isotopes; D004044:Dietary Proteins; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D007328:Insulin; D010743:Phospholipids; C033266:Menhaden oil; D010649:Phenylalanine; D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases