EFFECT OF ASPARTAME ON N-METHYL-D-ASPARTATE-SENSITIVE L-[H-3]GLUTAMATE BINDING-SITES IN RAT-BRAIN SYNAPTIC-MEMBRANES

Aspartame (l-aspartyl-l-phenylalanine methyl ester), an artificial low-calorie sweetener, was shown to dose-dependently inhibit l-[3H]glutamate binding to its N-methyl-d-aspartate-specific receptors. l-Aspartic acid, a major endogenous metabolite of aspartame, inhibited the binding more stronger than aspartame, while the other metabolites, l-phenylalanine and methanol, had no effect at the same concentration. Aspartame caused a significant change in the affinities of l-[3H]glutamate binding without altering the Vmax values of the binding, suggesting the inhibition is competitive. These in vitro findings suggested that aspartame may act directly on the N-methyl-d-aspartate-sensitive glutamate recognition sites in the brain synaptic membranes. © 1990.