Kynurenine pathway metabolism following prenatal KMO inhibition and in Mecp2
+/- mice, using liquid chromatography-tandem mass spectrometry.
Neurochem Int 2016;
100:110-119. [PMID:
27623092 PMCID:
PMC5115650 DOI:
10.1016/j.neuint.2016.09.012]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 07/22/2016] [Accepted: 09/09/2016] [Indexed: 12/17/2022]
Abstract
To quantify the full range of tryptophan metabolites along the kynurenine pathway, a liquid chromatography – tandem mass spectrometry method was developed and used to analyse brain extracts of rodents treated with the kynurenine-3-mono-oxygenase (KMO) inhibitor Ro61-8048 during pregnancy. There were significant increases in the levels of kynurenine, kynurenic acid, anthranilic acid and 3-hydroxy-kynurenine (3-HK) in the maternal brain after 5 h but not 24 h, while the embryos exhibited high levels of kynurenine, kynurenic acid and anthranilic acid after 5 h which were maintained at 24 h post-treatment. At 24 h there was also a strong trend to an increase in quinolinic acid levels (P = 0.055). No significant changes were observed in any of the other kynurenine metabolites. The results confirm the marked increase in the accumulation of some neuroactive kynurenines when KMO is inhibited, and re-emphasise the potential importance of changes in anthranilic acid. The prolonged duration of metabolite accumulation in the embryo brains indicates a trapping of compounds within the embryonic CNS independently of maternal levels. When brains were examined from young mice heterozygous for the meCP2 gene – a potential model for Rett syndrome - no differences were noted from control mice, suggesting that the proposed roles for kynurenines in autism spectrum disorder are not relevant to Rett syndrome, supporting its recognition as a distinct, independent, condition.
Pregnant rats were treated with an inhibitor of kynurenine-3-monoxygenase.
Levels of several kynurenine metabolites increased in the maternal and foetal brains.
The maternal changes at 5 h disappeared by 24 h, but were maintained in embryos.
No changes were noted in the brains of Mecp2+/− mice.
KMO inhibition but not Mecp2+/− suppression alters kynurenine metabolism.
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