Age-related changes in kynurenic acid production in rat brain

J B Gramsbergen, W Schmidt, W A Turski, R Schwarcz

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Abstract

Two separate in vitro assays were used to examine the biosynthesis of the broad spectrum excitatory amino acid receptor antagonist kynurenic acid (KYNA) during the life span of the adult rat. Assessment of KYNA's anabolic enzyme kynurenine aminotransferase revealed steady increases between 3 and 24 months of age in all five brain regions examined. No changes were observed in the liver. The changes were particularly pronounced in the cortex and in the striatum where enzyme activity increased three-fold during the period studied. KYNA production from its bioprecursor L-kynurenine was also investigated in tissue slices and was found to be significantly enhanced in the cortex and hippocampus of old animals. The effect of depolarizing agents or sodium replacement was virtually identical in tissues from young and old rats. These data, which are in excellent agreement with reports on an age-dependent increase of KYNA concentration in brain tissue, suggest an enhanced KYNA tone in the aged brain. Together with the reported decline in cerebral excitatory amino acid receptor densities with age, increased production of KYNA may play a role in cognitive and memory dysfunction in old animals.
Original languageEnglish
JournalBrain Research
Volume588
Issue number1
Pages (from-to)1-5
Number of pages4
ISSN0006-8993
Publication statusPublished - 14. Aug 1992

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Gramsbergen, J. B., Schmidt, W., Turski, W. A., & Schwarcz, R. (1992). Age-related changes in kynurenic acid production in rat brain. Brain Research, 588(1), 1-5.