ABSTRACT
Aspartame (APM) was studied in vivo for its ability to influence brain levels of the large neutral amino acids (LNAAs). the rates of hydroxylation of tryptophan and tyrosine, and the ability of a-methyl dopa, an LNAA drug, to reduce blood pressure. The artificial sweetener APM is a phenylalanine-containing dipeptide. Although only milligram quantities of the compound are normally to be consumed with foods, the possibility exists that excessive or abuse amounts might acutely be ingested by some individuals. Aspartame, phenylalanine, and aspartate were administered by gavage, as slurries in distilled water. Since APM affected brain levels of phenylalanine, tyrosine, and occasionally tryptophan, people next studied whether these changes influenced the rate of tyrosine or tryptophan hydroxylation in brain. The occasional decrease in brain tryptophan level probably followed from reduced uptake of this amino acid into brain, secondary to the large increments in blood levels of tyrosine and phenylalanine.
