Newsholme Eric A, Blomstrand Eva
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
J Nutr. 2006 Jan;136(1 Suppl):274S-6S. doi: 10.1093/jn/136.1.274S.
An account of the tryptophan (Trp)-5-hydroxytryptamine (5-HT)-central fatigue theory is provided and an explanation of how oral administration of BCAAs can decrease fatigue on the basis of this theory is given. The rate-limiting step in the synthesis of 5-HT is the transport of Trp across the blood-brain barrier. This transport is influenced by the fraction of Trp available for transport into the brain and the concentration of the other large neutral amino acids, including the BCAAs, which are transported via the same carrier system. During endurance exercise, there is an uptake of Trp by the brain, suggesting that this may increase the synthesis and release of 5-HT in the brain. Oral intake of BCAAs may reduce this uptake and also brain 5-HT synthesis and release, thereby delaying fatigue. Other hypotheses for the effect of BCAAs on central fatigue are included.
本文介绍了色氨酸（Trp）-5-羟色胺（5-HT）-中枢疲劳理论，并基于该理论解释了口服支链氨基酸（BCAAs）如何减轻疲劳。5-HT合成的限速步骤是Trp穿过血脑屏障的转运。这种转运受可用于转运至脑内的Trp比例以及其他大中性氨基酸（包括通过同一载体系统转运的BCAAs）浓度的影响。在耐力运动期间，脑会摄取Trp，这表明这可能会增加脑内5-HT的合成与释放。口服BCAAs可能会减少这种摄取以及脑内5-HT的合成与释放，从而延缓疲劳。文中还包括了关于BCAAs对中枢疲劳影响的其他假说。
