Micromolar concentration of kynurenic acid in rat small intestine

Amino Acids. 2008 Aug;35(2):503-5. doi: 10.1007/s00726-007-0631-z. Epub 2008 Jan 31.


Kynurenic acid is an antagonist of glutamate and alpha-7 nicotinic acetylcholine receptors and an agonist of the G: -protein-coupled receptor GPR35, which is predominantly expressed in immune and gastrointestinal tissues. In this study, we report that kynurenic acid is present in the lumen of rat small intestine in micromolar concentration sufficient to affect the GPR35 receptor. Moreover, we show that kynurenic acid can be produced by Escherichia coli. We suggest that kynurenic acid may modulate gastrointestinal function and integrity.

MeSH terms

  • Animals
  • Escherichia coli / chemistry
  • Escherichia coli / metabolism
  • Gastrointestinal Contents / chemistry*
  • Intestine, Small / chemistry*
  • Kynurenic Acid / analysis*
  • Kynurenic Acid / metabolism
  • Kynurenic Acid / pharmacology
  • Kynurenine / analogs & derivatives
  • Kynurenine / analysis
  • Male
  • Rats
  • Rats, Wistar
  • Receptors, G-Protein-Coupled / drug effects
  • Receptors, G-Protein-Coupled / metabolism


  • GPR35 protein, rat
  • Receptors, G-Protein-Coupled
  • Kynurenine
  • Kynurenic Acid