Evidence that the branched-chain amino acid L-valine prevents exercise-induced release of 5-HT in rat hippocampus.
The branched-chain amino acid L-valine competes with tryptophan for transport into the brain and has previously been shown to decrease brain 5-HT synthesis. The purpose of this study was to assess, using a combined venous catheterization and in vivo microdialysis method, the effect of pre-exercise L-valine administration on 5-hydroxytryptamine (5-HT) metabolism in the ventral hippocampus of rats submitted to an acute intensive treadmill running (120 min at 25 m x min(-1) followed by 150 min of recovery). The presented results include measurement of extracellular tryptophan (TRP), the 5-HT precursor, and extracellular 5-hydroxyindoleacetic acid (5-HIAA), the 5-HT metabolite. The data clearly demonstrate that exercise induces 5-HT release in the rat hippocampus: in control group, hippocampal 5-HT levels increase from 123.7 +/- 6.4% at the end of exercise to 133.9 +/- 6.4% after 60 min of recovery. Moreover, two hours of intensive running induced significant increases both in extracellular TRP levels (from 120 min of exercise to 30 min of recovery) and 5-HIAA levels (from 90 min of exercise to 90 min of recovery). Pre-exercise administration of L-valine prevents significantly the exercise-induced 5-HT release: 5-HT levels are maintained to baseline during exercise and recovery. With regard to the competitive effect of L-valine with TRP, we could observe a treatment-induced decrease in brain TRP levels (from 120 min of exercise to the end of recovery). Besides, L-valine does not prevent exercise-induced increase in 5-HIAA levels. The present study evidences that an acute intensive exercise stimulates 5-HT metabolism in the rat hippocampus, and that a pre-exercise administration of L-valine prevents, via a limiting effect on 5-HT synthesis, exercise-induced 5-HT release. This study provides some anwers to previous human and animal investigations, showing physiological and psychological benefits of branched-chain amino acids supplementation on performance.
Gomez-Merino
D
D
Department of Physiology: IMASSA-CERMA, Bretigny Sur Orge, France.
Béquet
F
F
Berthelot
M
M
Riverain
S
S
Chennaoui
M
M
Guezennec
C Y
CY
D000704:Analysis of Variance; D000818:Animals; D005110:Extracellular Space; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D010805:Physical Conditioning, Animal / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism; D014633:Valine / Q000008:administration & dosage / Q000494:pharmacology*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D014633:Valine