Amino BCAAS provide several metabolic and physiologic roles. Metabolically, BCAAs promote protein synthesis and turnover, signaling pathways, and metabolism of glucose. Oxidation of BCAAs may increase fatty acid oxidation and play a role in obesity.
Physiologically, BCAAs take on roles in the immune system and in brain function. BCAAs are broken down effectively by dehydrogenase and decarboxylase enzymes expressed by immune cells, and are required for lymphocyte growth and proliferation and cytotoxic T lymphocyte activity. Lastly, BCAAs share the same transport protein into the brain with aromatic amino acids (Trp, Tyr, and Phe).
Once in the brain BCAAs may have a role in protein synthesis, synthesis of neurotransmitters, and production of energy.
The BCKDH complex converts branched-chain amino acids into acyl-CoA derivatives, which after subsequent reactions are converted either into acetyl-CoA or succinyl-CoA that enter the citric acid cycle.
While most AMINO acids are oxidized in the liver, BCAAs are primarily oxidized in the skeletal muscle and other peripheral tissues.The effects of BCAA administration on muscles growth in rat diaphragm was tested, and concluded that not only does a mixture of BCAAs alone have the same effect on growth as a complete mixture of amino acids, but an amino acid mixture with all but BCAAs has no effect on rat diaphragm muscle growth.
Administration of either isoleucine or valine alone had no effect on muscle growth..
.although administration of leucine alone appears to be nearly as effective as the complete mixture of BCAAs. Leucine indirectly activates p70 S6 kinase as well as stimulates assembly of the eIF4F complex, which are essential for mRNA binding in translational initiation.
P70 S6 kinase is part of the mammalian target of rapamycin complex (mTOR) signaling pathway, and has been shown to allow adaptive hypertrophy and recovery of rat muscle. At rest protein infusion stimulates protein synthesis 30 minutes after start of infusion, and protein synthesis stays elevated for another 90 minutes.
Infusion of leucine at rest produces a six-hour stimulatory effect..
…and increased protein synthesis by phosphorylation of p70 S6 kinase in skeletal muscles.
Following resistance exercise..
..administration, a resistance exercise session does not affect phosphorylation and even produces a decrease in Akt phosphorylation.
Some phosphorylation of p70 S6 kinase was discovered. When BCAAs were administered following a training session, sufficient phosphorylation of p70 S6 kinase and S6 indicated activation of the signaling cascade.
Dietary AMINO bcaas supplementation has been used clinically to aid in the recovery of burn victims. However, a 2006 paper suggests that the concept of nutrition supplemented with all BCAAs for burns, trauma, and sepsis should be abandoned for a more promising leucine-only-supplemented nutrition that requires further evaluation