scholarly journals Effects of Supplementation of Branched-Chain Amino Acids to Reduced-Protein Diet on Skeletal Muscle Protein Synthesis and Degradation in the Fed and Fasted States in a Piglet Model

Nutrients ◽  
2016 ◽  
Vol 9 (1) ◽  
pp. 17 ◽  
Author(s):  
Liufeng Zheng ◽  
Hongkui Wei ◽  
Pingli He ◽  
Shengjun Zhao ◽  
Quanhang Xiang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Branched Chain Amino Acids ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Branched Chain ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

scholarly journals Skeletal muscle protein synthesis and degradation in patients with chronic renal failure

1994 ◽  
Vol 45 (5) ◽  
pp. 1432-1439 ◽  
Author(s):  
Giacomo Garibotto ◽  
Rodolfo Russo ◽  
Antonella Sofia ◽  
Maria Rita Sala ◽  
Cristina Robaudo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Renal Failure ◽  
Protein Synthesis ◽  
Chronic Renal Failure ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Growth hormone acutely stimulates forearm muscle protein synthesis in normal humans

1991 ◽  
Vol 260 (3) ◽  
pp. E499-E504 ◽  
Author(s):  
D. A. Fryburg ◽  
R. A. Gelfand ◽  
E. J. Barrett
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Igf I ◽  
Normal Humans

The short-term effects of growth hormone (GH) on skeletal muscle protein synthesis and degradation in normal humans are unknown. We studied seven postabsorptive healthy men (age 18-23 yr) who received GH (0.014 micrograms.kg-1.min-1) via intrabrachial artery infusion for 6 h. The effects of GH on forearm amino acid and glucose balances and on forearm amino acid kinetics [( 3H]Phe and [14C]Leu) were determined after 3 and 6 h of the GH infusion. Forearm deep vein GH rose to 35 +/- 6 ng/ml in response to GH, whereas systemic levels of GH, insulin, and insulin-like growth factor I (IGF-I) were unchanged. Forearm glucose uptake did not change during the study. After 6 h, GH suppressed forearm net release (3 vs. 6 h) of Phe (P less than 0.05), Leu (P less than 0.01), total branched-chain amino acids (P less than 0.025), and essential neutral amino acids (0.05 less than P less than 0.1). The effect on the net balance of Phe and Leu was due to an increase in the tissue uptake for Phe (71%, P less than 0.05) and Leu (37%, P less than 0.005) in the absence of any significant change in release of Phe or Leu from tissue. In the absence of any change in systemic GH, IGF-I, or insulin, these findings suggest that locally infused GH stimulates skeletal muscle protein synthesis. These findings have important physiological implications for both the role of daily GH pulses and the mechanisms through which GH can promote protein anabolism.

scholarly journals Amino Acid Trafficking and Skeletal Muscle Protein Synthesis: A Case of Supply and Demand

2021 ◽  
Vol 9 ◽  
Author(s):  
James P. White
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Energy Production ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Supply And Demand ◽  
Mechanical Stimuli ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Branched Chain

Skeletal muscle protein synthesis is a highly complex process, influenced by nutritional status, mechanical stimuli, repair programs, hormones, and growth factors. The molecular aspects of protein synthesis are centered around the mTORC1 complex. However, the intricacies of mTORC1 regulation, both up and downstream, have expanded overtime. Moreover, the plastic nature of skeletal muscle makes it a unique tissue, having to coordinate between temporal changes in myofiber metabolism and hypertrophy/atrophy stimuli within a tissue with considerable protein content. Skeletal muscle manages the push and pull between anabolic and catabolic pathways through key regulatory proteins to promote energy production in times of nutrient deprivation or activate anabolic pathways in times of nutrient availability and anabolic stimuli. Branched-chain amino acids (BCAAs) can be used for both energy production and signaling to induce protein synthesis. The metabolism of BCAAs occur in tandem with energetic and anabolic processes, converging at several points along their respective pathways. The fate of intramuscular BCAAs adds another layer of regulation, which has consequences to promote or inhibit muscle fiber protein anabolism. This review will outline the general mechanisms of muscle protein synthesis and describe how metabolic pathways can regulate this process. Lastly, we will discuss how BCAA availability and demand coordinate with synthesis mechanisms and identify key factors involved in intramuscular BCAA trafficking.

scholarly journals BCATm deficiency ameliorates endotoxin-induced decrease in muscle protein synthesis and improves survival in septic mice

2010 ◽  
Vol 299 (3) ◽  
pp. R935-R944 ◽  
Author(s):  
Charles H. Lang ◽  
Christopher J. Lynch ◽  
Thomas C. Vary
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Interactions ◽  
Knockout Mice ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Initiation Factor ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Branched Chain

Endotoxin (LPS) and sepsis decrease mammalian target of rapamycin (mTOR) activity in skeletal muscle, thereby reducing protein synthesis. Our study tests the hypothesis that inhibition of branched-chain amino acid (BCAA) catabolism, which elevates circulating BCAA and stimulates mTOR, will blunt the LPS-induced decrease in muscle protein synthesis. Wild-type (WT) and mitochondrial branched-chain aminotransferase (BCATm) knockout mice were studied 4 h after Escherichia coli LPS or saline. Basal skeletal muscle protein synthesis was increased in knockout mice compared with WT, and this change was associated with increased eukaryotic initiation factor (eIF)-4E binding protein-1 (4E-BP1) phosphorylation, eIF4E·eIF4G binding, 4E-BP1·raptor binding, and eIF3·raptor binding without a change in the mTOR·raptor complex in muscle. LPS decreased muscle protein synthesis in WT mice, a change associated with decreased 4E-BP1 phosphorylation as well as decreased formation of eIF4E·eIF4G, 4E-BP1·raptor, and eIF3·raptor complexes. In BCATm knockout mice given LPS, muscle protein synthesis only decreased to values found in vehicle-treated WT control mice, and this ameliorated LPS effect was associated with a coordinate increase in 4E-BP1·raptor, eIF3·raptor, and 4E-BP1 phosphorylation. Additionally, the LPS-induced increase in muscle cytokines was blunted in BCATm knockout mice, compared with WT animals. In a separate study, 7-day survival and muscle mass were increased in BCATm knockout vs. WT mice after polymicrobial peritonitis. These data suggest that elevating blood BCAA is sufficient to ameliorate the catabolic effect of LPS on skeletal muscle protein synthesis via alterations in protein-protein interactions within mTOR complex-1, and this may provide a survival advantage in response to bacterial infection.

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