Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10533714 | Analytical Biochemistry | 2012 | 9 Pages |
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 8Â nM, respectively, but 3-HK levels were below the limit of detection (<2Â nM). Systemic injection of kynurenine (100Â mg/kg, i.p.) did not affect extracellular tryptophan but produced detectable levels of extracellular 3-HK (peak after 2-3Â h: â¼50Â nM) and raised extracellular QUIN levels (peak after 2Â h: â¼105Â 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.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Francesca M. Notarangelo, Hui-Qiu Wu, Anthony Macherone, David R. Graham, Robert Schwarcz,