Journal
JOURNAL OF NUTRITION
Volume 135, Issue 3, Pages 376-382Publisher
OXFORD UNIV PRESS
DOI: 10.1093/jn/135.3.376
Keywords
translation initiation; gastrocnemius muscle; mTOR
Categories
Funding
- NIDDK NIH HHS [DK 15658] Funding Source: Medline
Ask authors/readers for more resources
Oral administration of a single bolus of leucine in an amount equivalent to the daily intake (1.35 g/kg body wt) enhances skeletal muscle protein synthesis in food-deprived rats. To elucidate whether smaller amounts of leucine can also stimulate protein synthesis, rats were administered the amino acid at concentrations ranging from 0.068 to 1.35 g/kg body wt by oral gavage. Thirty minutes following the administration of doses of leucine as low as 0.135 g/kg body wt, skeletal muscle protein synthesis was significantly greater than control values. The increase in protein synthesis was associated with changes in the regulation of biomarkers of mRNA translation initiation as evidenced by upregulated phosphorylation of the translational repressor, eukaryotic initiation factor (elF)4E-binding protein 1 (4E-BP1), the association of elF4G with the mRNA cap binding protein elF4E, and the phosphorylation of the 70-kDa ribosomal protein S6 kinase. Alterations in the phosphorylation of elF4G, as well as the association of 4E-BP1 with elF4E, were observed following leucine administration; however, these changes appeared to be biphasic with maximal changes occurring when circulating insulin concentrations were elevated. Thus it appears that leucine administration affects mRNA translation and skeletal muscle protein synthesis through modulation of multiple biomarkers of mRNA translation. The ability of small doses of leucine to stimulate skeletal muscle protein synthesis suggests that future research on the regulation of skeletal muscle protein synthesis by orally administered leucine will be feasible in humans.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available