title: Fish oil positively regulates anabolic signalling alongside an increase in whole-body gluconeogenesis in ageing skeletal muscle.
abstract: OBJECTIVE
  Fish oil, containing mainly long-chain n-3 polyunsaturated fatty acids (LCn-3PUFA), has been found to acutely stimulate protein synthesis and insulin-mediated glucose metabolism. However, the underlying mechanism and more prolonged effect of fish oil during ageing remain to be determined.
  
  
  METHODS
  Fish oil (EPAX6000; 49.6 % eicosapentaenoic acid, 50.4 % docosahexaenoic acid) or control oil (60 % olive, 40 % soy) supplementation was delivered, via chocolate-derived sweets, to rats for 8 weeks. Throughout the study, food intake and body weight were recorded and body composition was investigated using EchoMRI. During the last 40 min of a 6 h infusion, with labelled dextrose ([U-(13)C]glucose) and amino acids ([1-(13)C]phenylalanine), blood samples were collected to assess glucose and phenylalanine kinetics. Soleus and longissimus dorsi muscles were extracted for protein and mRNA analyses.
  
  
  RESULTS
  Fish oil had no effect on food intake or body composition. An increased whole-body glucose turnover, mainly accounted for via an increase in endogenous glucose production, was observed with fish oil feeding. No effects on whole-body phenylalanine turnover were observed. In longissimus dorsi, fish oil augmented the phosphorylation of phosphoinositide 3-kinase (PI3K)([Tyr458]) (P = 0.04) and 70 kDa ribosomal protein S6 kinase (p70s6k)([Thr389]) (P = 0.04). There were no differences in protein kinase B (Akt)([Ser473]), mammalian target of rapamycin (mTOR)([Ser2448]), protein phosphatase 2A (PP2A) 56 kDa regulatory B subunit γ (PP2A-B56-γ), forkhead box containing proteins O-subclass 3a (FOX03a)([Ser253]) or inflammatory markers (Interleukin-6, Interleukin-1 β, tumour necrosis factor-α, and cyclooxygenase-2).
  
  
  CONCLUSIONS
  Our data suggest that the fish oil may stimulate endogenous glucose production and increase anabolic signalling in ageing rats.
authors.affiliation: Musculoskeletal Research Programme, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK.
authors.forename: Torkamol
authors.initials: T
authors.lastname: Kamolrat
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Gray
authors.forename: M Carole
authors.initials: MC
authors.lastname: Thivierge
mesh_terms: D000375:Aging / Q000187:drug effects*; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D002784:Cholesterol / Q000097:blood; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D019587:Dietary Supplements; D002149:Energy Intake / Q000187:drug effects; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage; D005395:Fish Oils / Q000008:administration & dosage*; D005943:Gluconeogenesis / Q000187:drug effects*; D007328:Insulin / Q000097:blood; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D051381:Rats; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D014280:Triglycerides / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D002784:Cholesterol; D051546:Cyclooxygenase 2; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D007328:Insulin; D053583:Interleukin-1beta; D015850:Interleukin-6; D019869:Phosphatidylinositol 3-Kinases; D054648:Protein Phosphatase 2; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; C489691:Ptgs2 protein, rat; C546845:mTOR protein, rat; C513662:B56alpha protein, rat