Ethanol-induced increase in brain concentrations of administered neutral amino acids

Summary Ethanol 2 g kg^–1 i.p. to rat increased the concentrations in the brain of administered large neutral amino acids (tyrosine, tryptophan, 5-hydroxytryptophan and -methyldopa). We have previously found a similar effect of ethanol on administered l-Dopa, resulting in increased brain/plasma ratios of dopa. Since large neutral amino acids are known to compete with each other for the carrier-mediated transport into the brain we suggest that the increased concentrations of the administered amino acids in the brain are at least partly the consequence of the ethanol-induced decrease in plasma amino acids observed previously.