Oral branched-chain amino acid supplements that reduce brain serotonin during exercise in rats also lower brain catecholamines. Amino Acids 2013 Nov;45(5):1133-42
Date
08/02/2013Pubmed ID
23904096DOI
10.1007/s00726-013-1566-1Scopus ID
2-s2.0-84886284922 (requires institutional sign-in at Scopus site) 32 CitationsAbstract
Exercise raises brain serotonin release and is postulated to cause fatigue in athletes; ingestion of branched-chain amino acids (BCAA), by competitively inhibiting tryptophan transport into brain, lowers brain tryptophan uptake and serotonin synthesis and release in rats, and reputedly in humans prevents exercise-induced increases in serotonin and fatigue. This latter effect in humans is disputed. But BCAA also competitively inhibit tyrosine uptake into brain, and thus catecholamine synthesis and release. Since increasing brain catecholamines enhances physical performance, BCAA ingestion could lower catecholamines, reduce performance and thus negate any serotonin-linked benefit. We therefore examined in rats whether BCAA would reduce both brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Sedentary and exercising rats received BCAA or vehicle orally; tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis rates were measured 1 h later in brain. BCAA reduced brain tryptophan and tyrosine concentrations, and serotonin and catecholamine synthesis. These reductions in tyrosine concentrations and catecholamine synthesis, but not tryptophan or serotonin synthesis, could be prevented by co-administering tyrosine with BCAA. Complete essential amino acid mixtures, used to maintain or build muscle mass, were also studied, and produced different effects on brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Since pharmacologically increasing brain catecholamine function improves physical performance, the finding that BCAA reduce catecholamine synthesis may explain why this treatment does not enhance physical performance in humans, despite reducing serotonin synthesis. If so, adding tyrosine to BCAA supplements might allow a positive action on performance to emerge.
Author List
Choi S, Disilvio B, Fernstrom MH, Fernstrom JDAuthor
Sujean Choi PhD in the School of Allied Health department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
Amino Acids, Branched-ChainAnimals
Brain
Catecholamines
Dietary Supplements
Exercise
Humans
Rats
Rats, Sprague-Dawley
Serotonin
