title: l-Leucine Increases Skeletal Muscle IGF-1 but Does Not Differentially Increase Akt/mTORC1 Signaling and Serum IGF-1 Compared to Ursolic Acid in Response to Resistance Exercise in Resistance-Trained Men.
abstract: Ursolic acid administration following resistance exercise increases mammalian target of rapamycin complex 1 (mTORC1) activity and skeletal muscle IGF-1 concentration in murines in a manner similar to l-leucine yet remains unexamined in humans. This study examined serum and skeletal muscle insulin-like growth factor-1 (IGF-1) and Akt/mTORC1 signaling activity following ingestion of either ursolic acid or l-leucine immediately after resistance exercise.
  
  
  
  Nine resistance-trained men performed 3 lower-body resistance exercise sessions involving 4 sets of 8-10 repetitions at 75%-80% one repetition maximum (1-RM) on the angled leg press and knee extension exercises. Immediately following each session, participants orally ingested 3 g cellulose placebo (PLC), l-leucine (LEU), or ursolic acid (UA). Blood samples were obtained pre-exercise and at 0.5, 2, and 6 hours postexercise. Muscle biopsies were obtained pre-exercise and at 2 and 6 hours postexercise.
  
  
  
  Plasma leucine increased in LEU at 2 hours postexercise compared to PLC (p = 0.04). Plasma ursolic acid increased in UA at 2 h and 6 hours postexercise compared to PLC and LEU (p < 0.003). No significant differences were observed for serum insulin (p = 0.98) and IGF-1 (p = 0.99) or skeletal muscle IGF-1 receptor (IGF-1R; p = 0.84), Akt (p = 0.55), mTOR (p = 0.09), and p70S6K (p = 0.98). Skeletal muscle IGF-1 was significantly increased in LEU at 2 hours postexercise (p = 0.03) and 6 hours postexercise (p = 0.04) compared to PLC and UA.
  
  
  
  Three grams of l-leucine and ursolic acid had no effect on Akt/mTORC1 signaling or serum insulin or IGF-1; however, l-leucine increased skeletal muscle IGF-1 concentration in resistance-trained men.
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: David D
authors.initials: DD
authors.lastname: Church
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Neil A
authors.initials: NA
authors.lastname: Schwarz
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Mike B
authors.initials: MB
authors.lastname: Spillane
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Sarah K
authors.initials: SK
authors.lastname: McKinley-Barnard
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Tom L
authors.initials: TL
authors.lastname: Andre
authors.affiliation: b Mass Spectrometry Center , College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Ramirez
authors.affiliation: a Exercise and Biochemical Nutrition Lab, Department of Health , Human Performance, and Recreation, College of Arts and Sciences, Baylor University , Waco , Texas.
authors.forename: Darryn S
authors.initials: DS
authors.lastname: Willoughby
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D004032:Diet; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007930:Leucine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000187:drug effects; D055070:Resistance Training; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D014315:Triterpenes / Q000008:administration & dosage* / Q000097:blood; D055815:Young Adult; D000097245:Ursolic Acid
chemical_list: D007328:Insulin; D007334:Insulin-Like Growth Factor I; D007930:Leucine; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D058570:TOR Serine-Threonine Kinases; D014315:Triterpenes; D000097245:Ursolic Acid
keywords: branched-chain amino acid; cell signaling; muscle protein synthesis; resistance exercise