Gas chromatography/tandem mass spectrometry detection of extracellular kynurenine and related metabolites in normal and lesioned rat brain

Francesca M. Notarangelo, Hui Qiu Wu, Anthony Macherone, David R. Graham, Robert Schwarcz

Research output: Contribution to journalArticlepeer-review

Abstract

We describe here a gas chromatography-tandem mass spectrometry (GC/MS/MS) method for the sensitive and concurrent determination of extracellular tryptophan and the kynurenine pathway metabolites kynurenine, 3-hydroxykynurenine (3-HK), and quinolinic acid (QUIN) in rat brain. This metabolic cascade is increasingly linked to the pathophysiology of several neurological and psychiatric diseases. Methodological refinements, including optimization of MS conditions and the addition of deuterated standards, resulted in assay linearity to the low nanomolar range. Measured in samples obtained by striatal microdialysis in vivo, basal levels of tryptophan, kynurenine, and QUIN were 415, 89, and 8 nM, respectively, but 3-HK levels were below the limit of detection (<2 nM). Systemic injection of kynurenine (100 mg/kg, i.p.) did not affect extracellular tryptophan but produced detectable levels of extracellular 3-HK (peak after 2-3 h: ∼50 nM) and raised extracellular QUIN levels (peak after 2 h: ∼105 nM). The effect of this treatment on QUIN, but not on 3-HK, was potentiated in the N-methyl-D-aspartate (NMDA)-lesioned striatum. Our results indicate that the novel methodology, which allowed the measurement of extracellular kynurenine and 3-HK in the brain in vivo, will facilitate studies of brain kynurenines and of the interplay between peripheral and central kynurenine pathway functions under physiological and pathological conditions.

Original languageEnglish (US)
Pages (from-to)573-581
Number of pages9
JournalAnalytical biochemistry
Volume421
Issue number2
DOIs
StatePublished - Feb 15 2012

Keywords

  • 3-Hydroxykynurenine
  • Microdialysis
  • Quinolinic acid
  • Selective reaction monitoring
  • Tandem mass spectrometry
  • Tryptophan

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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