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Cited by 194Muscle metabolism and nutritionMuscle Physiology and DisordersNutrition and Health in Aging

Excess Leucine Intake Enhances Muscle Anabolic Signaling but Not Net Protein Anabolism in Young Men and Women

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Glynn, Erin L., Fry, Christopher S., Drummond, Micah J., Timmerman, Kyle L., Dhanani, Shaheen, Volpi, Elena, Rasmussen, Blake B.·2010·The Journal of Nutrition
DOI 10.3945/jn.110.127647PMC PMC2955876
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Abstract

Essential amino acids (EAA) stimulate skeletal muscle protein synthesis (MPS) in humans. Leucine may have a greater stimulatory effect on MPS than other EAA and/or decrease muscle protein breakdown (MPB). To determine the effect of 2 different leucine concentrations on muscle protein turnover and associated signaling, young men (n = 6) and women (n = 8) ingested 10 g EAA in 1 of 2 groups: composition typical of high quality proteins (CTRL; 1.8 g leucine) or increased leucine concentration (LEU; 3.5 g leucine). Participants were studied for 180 min postingestion. Fractional synthetic rate and leg phenylalanine and leucine kinetics were assessed on muscle biopsies using stable isotopic techniques. Signaling was determined by immunoblotting. Arterial leucine concentration and delivery to the leg increased in both groups and was significantly higher in LEU than in CTRL; however, transport into the muscle and intracellular availability did not differ between groups. MPS increased similarly in both groups 60 min postingestion. MPB decreased at 60 min only in LEU, but net muscle protein balance improved similarly. Components of mammalian target of rapamycin (mTOR) signaling were improved in LEU, but no changes were observed in ubiquitin-proteasome system signaling. Changes in light chain 3 and mTOR association with Unc-51-like kinase 1 indicate autophagy decreased more in LEU. We conclude that in 10 g of EAA, the leucine content typical of high quality proteins (~1.8 g) is sufficient to induce a maximal skeletal muscle protein anabolic response in young adults, but leucine may play a role in autophagy regulation.

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  • In an animal model, leucine ingestion (alone and with carbohydrate) consumed between meals (135 min post-consumption) extends protein synthesis by increasing the energy status of the muscle fiber.

    “Wilson and colleagues [157] have recently demonstrated, in an animal model, that leucine ingestion (alone and with carbohydrate) consumed between meals (135 min post-consumption) extends protein synthesis by increasing the energy status of the muscle fiber.”

    From International Society of Sports Nutrition Position Stand: protein and exercise (2017) · cites this paper as [157]

  • The response of protein synthesis to leucine may occur in a dose-dependent fashion, plateauing at approximately two g at rest, and increasing up to 3.5 g when ingestion occurs after completion of a 60-min bout of moderate intensity cycling.

    “this response may occur in a dose-dependent fashion, plateauing at approximately two g at rest [31, 157], and increasing up to 3.5 g when ingestion occurs after completion of a 60-min bout of moderate intensity cycling [159].”

    From International Society of Sports Nutrition Position Stand: protein and exercise (2017) · cites this paper as [157]

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Authors
Glynn, E. L., Fry, C. S., Drummond, M. J., Timmerman, K. L., Dhanani, S., Volpi, E., & Rasmussen, B. B.
Affiliations
The University of Texas Medical Branch at Galveston (US)
Corresponding author
Rasmussen, Blake B.
ORCID
Venue
The Journal of Nutrition
Publisher
Elsevier BV
Published
2010-11
Volume
140
Issue
11
Pages
1970-1976
ISSN
0022-3166 (ISSN-L)
DOI
10.3945/jn.110.127647
PMC
PMC2955876
OpenAlex
W2126031921
Cited by
194
References
14
Citations by year
2026: 4 · 2025: 4 · 2024: 9 · 2023: 9 · 2022: 6 · 2021: 4 · 2020: 9 · 2019: 12 · 2018: 15 · 2017: 8 · 2016: 22 · 2015: 16 · 2014: 19 · 2013: 21 · 2012: 24
FWCI
7.98
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Nutrition (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (NIH T32)
  • National Institute on Aging (P30AG024832)
  • National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01AR049877, AR049877)
  • National Center for Research Resources (UL1RR029876)
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (T32-HD-07539, T32HD007539)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Health Sciences › Medicine › Physiology › Nutrition and Health in Aging
Keywords
leucine, essential amino acids, skeletal muscle protein synthesis, muscle protein degradation, net protein balance, mTOR signaling, autophagy, ubiquitin-proteasome system, leucine kinetics, muscle protein turnover, young adults, sex differences
MeSH terms
Mechanistic Target of Rapamycin Complex 1, Adult, Autophagy, Biopsy, Carbon Isotopes, Female, Humans, Infusions, Intravenous, Kinetics, Leucine, Male, Muscle Proteins, Phenylalanine, Proteins, Regional Blood Flow, Transcription Factors, Signal Transduction, Biomarkers, Muscle, Skeletal, Ubiquitin, Multiprotein Complexes, Proteasome Endopeptidase Complex, Quadriceps Muscle, TOR Serine-Threonine Kinases

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