Possible Interaction: Glutamine and Kynurenic Acid

“BACKGROUND Kynurenic acid (KYNA)--a tryptophan metabolite--elicits antagonistic activity against glutaminergic and cholinergic receptors; it has been suggested to have some relationship with neurological disorders.”

“ Glutamine (Gln), which is a metabolic precursor of glutamate in astrocytes and L‐system substrate in both cell types, inhibited KYNA synthesis both in neurons and in astrocytes (IC50: 268 and 318 μM, respectively).”

“Inhibition of glutaminergic synaptic transmission by kynurenic acid (50μM) and the NMDA‐antagonist D‐2‐amino‐5‐phosphonovaleric acid (APV; 50μM) led to a marked shortening of the depolarizations.”

“The endogenous … metabolite, kynurenic acid , antagonized excitations induced by …-methyl-D-aspartic, quisqualic, L-glutamic and kainic acid as well as the excitatory postsynaptic potential (EPSP) evoked in caudate cells by stimulation … the corticocaudate pathway, while action potentials elicited by an intracellularly applied depolarizing current were only slightly affected.”

“Ten out of 19 amino acids (specifically, leucine, isoleucine, phenylalanine, methionine, tyrosine, alanine, cysteine, glutamine , glutamate, and aspartate) significantly reduced KYNA formation at 1 mmol/L. These amino acids showed inhibitory effects in a dose-dependent manner, and partially inhibited KYNA production at physiological concentrations.”