par Pat G le 09/06/2008 14h45
@Gromit stp
En lisant un post sur le mega-dosing de BCAA sur intensemuscle je suis tombé sur ça...
A dose-finding study on the effects of branch chain amino acids on surrogate markers of brain dopamine function.
Gijsman HJ, Scarna A, Harmer CJ, McTavish SB, Odontiadis J, Cowen PJ, Goodwin GM.
University of Oxford, Department of Psychiatry, Warneford Hospital, Oxford OX3 7JX, UK.
RATIONALE: We have previously shown in healthy volunteers that an amino acid mixture lacking tyrosine and phenylalanine reduces tyrosine availability to the brain and produces cognitive and neuroendocrine effects consistent with reduced dopamine function. This could provide a potential nutritional approach to disorders such as mania and schizophrenia, which are characterised by overactivity of dopamine pathways. The amino acid mixture we tested previously is unpalatable, whereas mixtures containing only branch chain amino acids can be made more palatable. However, the effects of such mixtures on dopamine function in humans have not been studied. OBJECTIVE: To assess the tolerability of different doses of branch chain amino acids and to measure their effects on neuroendocrine and cognitive measures sensitive to changes in dopamine function. METHODS: We used a randomised, double-blind, cross-over design in 12 healthy volunteers to assess the effect of single oral doses of 10 g, 30 g and 60 g branch chain amino acids on plasma prolactin and a test of spatial recognition memory RESULTS: The branch chain amino acids were well tolerated. The availability of tyrosine for brain catecholamine synthesis decreased in a dose-related manner. As hypothesised, the drink increased both the plasma prolactin and the latency to respond on the spatial recognition memory task. CONCLUSIONS: A drink containing branch chain amino acids is well tolerated in healthy volunteers and produces effects consistent with lowered dopamine function.
''In addition to the effects on tryptophan levels, BCAA's may have other effects on the CNS, both direct and indirect. A well established property is that BCAA supplements reduce dopamine levels, an effect that occurs in many sample populations including healthy human volunteers (at doses of 10, 30, and 60 g) [40]. There are two possible reasons for this effect. The primary reason is that BCAA's competitively inhibit transport of phenylalanine and tyrosine to the brain (similar to the inhibition of tryptophan) [41]. Secondly, BCAA's also simultaneously lower the plasma levels of key amino acids required for neurotransmitter synthesis. This occurs because the BCAA's stimulate protein synthesis, but other amino acids are also required for protein synthesis. This issue does not occur with whole protein sources, which also provide the other amino acids required for protein synthesis. BCAA's also consequently lower levels of norepinephrine [42]. In conditions such as mania and hepatic encephalopathy, this effect of BCAA's can be beneficial [41-42]. However, decreased levels of NE and dopamine are generally not desirable in normal individuals. Functional changes induced in healthy humans by BCAA ingestion so far include impaired spatial memory and elevated plasma prolactin [40-41]. There is also a reference in the literature to BCAA ingestion increasing appetite [43].''
qu'est ce que tu penses de cette étude ?
t'as pas mal ! j'ai pas mal !
t'as pas mal ! j'ai pas mal !
Rocky IV