Possible Interaction: Kynurenic Acid and Tryptophan

“Excess of Trp is responsible for overloading the brain with neuroactive compounds: serotonin, kynurenic acid , quinolinic acid and/or oxindole, which contribute to neurotransmission imbalance accompanying hyperammonemia.”

“These results show that the urinary excretory ratio of anthranilic acid kynurenic acid is potentially the most sensitive and appropriate surrogate breakpoint index to predict the UL of L-Trp.”

“It has long been known that induction of pterin synthesis, as measured by increased levels of neopterin in cerebrospinal fluid, serum and … cells suggested a possible functional biochemical link between these two pathways.3 It has also now convincingly been demonstrated that stimulation of L-tryptophan metabolism …), kynurenic acid, ….”

“In argon‐bubbled solutions, the quenching of triplet KNA by NTrpH results in the formation of KNA•− and NTrp• radicals.”

“The study revealed that uptake of periphery-derived kynurenine and tryptophan into the brain enhances kynurenic acid production in the brain, and the three factors produce amplification effect involved in the role of central-peripheral linkage in central fatigue, triggering cognitive dysfunction.”

“During the exposure the urinary excretions of xanthurenic acid and kynurenic acid after i. p. administration of tryptophan increased significantly in both experimental groups.”

“an analogue of kynurenine that is able to direct the flow of tryptophan metabolites toward the synthesis of KYNA, significantly increased the KYNA concentration in the hippocampal dialysate and significantly potentiated the effect of tryptophan on the accumulation of KYNA in the brain and other organs.”

“Both QUIN and KYNA tissue levels are increased following tryptophan loading, how-ever such a change in tissue levels does not necessarily reflect a change in their concentrations in the active compartment, the extracellular fluid (ECF).”

“Administration of L-tryptophan was less effective than L-kynurenine in increasing ECF kynurenic acid concentrations and did so at a considerably later time interval (6 hr).(ABSTRACT TRUNCATED AT 250 WORDS)”

“Probenecid, a blocker of organic acid transport, and tryptophan , a precursor of endogenous brain kynurenic acid, increased the time frame in which kynurenic acid exerted its protective effects.”