期刊
ANALYTICAL BIOCHEMISTRY
卷 421, 期 2, 页码 573-581出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ab.2011.12.032
关键词
3-Hydroxykynurenine; Microdialysis; Quinolinic acid; Selective reaction monitoring; Tandem mass spectrometry; Tryptophan
资金
- National Institutes of Health (NIH) [AG022074, NS057715, MH085554]
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: similar to 50 nM) and raised extracellular QUIN levels (peak after 2 h: similar to 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. (C) 2011 Elsevier Inc. All rights reserved.
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