title: Adding protein to a carbohydrate supplement provided after endurance exercise enhances 4E-BP1 and RPS6 signaling in skeletal muscle.
abstract: To examine the role of both endurance exercise and nutrient supplementation on the activation of mRNA translation signaling pathways postexercise, rats were subjected to a 3-h swimming protocol. Immediately following exercise, the rats were provided with a solution containing either 23.7% wt/vol carbohydrates (CHO), 7.9% wt/vol protein (Pro), 31.6% wt/vol (23.7% wt/vol CHO + 7.9% wt/vol Pro) carbohydrates and Pro (CP), or a placebo (EX). The rats were then killed at 0, 30, and 90 min postexercise, and phosphorylation states of mammalian target of rapamycin (mTOR), ribosomal S6 kinase (p70(S6K)), ribosomal protein S6 (rpS6), and 4E-binding protein 1 (4E-BP1), were analyzed by immunoblot analysis in the red and white quadriceps muscle. Results demonstrated that rat groups provided with any of the three nutritional supplements (CHO, Pro, CP) transiently increased the phosphorylation states of mTOR, 4E-BP1, rpS6, and p70(S6K) compared with EX rats. Although CHO, Pro, and CP supplements phosphorylated mTOR and p70(S6K) after exercise, only CP elevated the phosphorylation of rpS6 above all other supplements 30 min postexercise and 4E-BP1 30 and 90 min postexercise. Furthermore, the phosphorylation states of 4E-BP1 (r(2) = 0.7942) and rpS6 (r(2) = 0.760) were highly correlated to insulin concentrations in each group. These results suggest that CP supplementation may be most effective in activating the mTOR-dependent signaling pathway in the postprandial state postexercise, and that there is a strong relationship between the insulin concentration and the activation of enzymes critical for mRNA translation.
authors.affiliation: Dept. of Kinesiology and Health Education, Bellmont Hall 222, The Univ. of Texas at Austin, Austin, Texas 78712-0360, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Morrison
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hara
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D019893:Ribosomal Protein S6 Kinases / Q000096:biosynthesis* / Q000235:genetics; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013550:Swimming / Q000502:physiology; D058570:TOR Serine-Threonine Kinases
chemical_list: D001786:Blood Glucose; D002352:Carrier Proteins; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; C499526:Eif4ebp1 protein, rat; D007004:Hypoglycemic Agents; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D011494:Protein Kinases; C546845:mTOR protein, rat; D019893:Ribosomal Protein S6 Kinases; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D005947:Glucose