Kynurenine Pathway Enzymes in Brain

Responses to Ischemic Brain Injury Versus Systemic Immune Activation

Kuniaki Saito, Thaddeus S. Nowak, Kazuhiko Suyama, Bonnie J. Quearry, Misato Saito, Jeffrey S. Crowley, Sanford P. Markey, Melvyn P. Heyes

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

Accumulation of l‐kynurenine and quinolinic acid (QUIN) in the brain occurs after either ischemic brain injury or after systemic administration of pokeweed mitogen. Although conversion of l‐[13C6]tryptophan to [13C6]‐QUIN has not been demonstrated in brain either from normal gerbils or from gerbils given pokeweed mitogen, direct conversion in brain tissue does occur 4 days after transient cerebral ischemia. Increased activities of enzymes distal to indoleamine‐2,3‐dioxygenase may determine whether l‐kynurenine is converted to QUIN. One day after 10 min of cerebral ischemia, the activities of kynureninase and 3‐hydroxy‐3,4‐dioxygenase were increased in the hippocampus, but local QUIN levels and the activities of the indoleamine‐2,3‐dioxygenase and kynurenine‐3‐hydroxylase were unchanged. By days 2 and 4 after ischemia, however, the activities of all of these enzymes in the hippocampus as well as QUIN levels were significantly increased. Kynurenine aminotransferase activity in the hippocampus was unchanged on days 1 and 2 after ischemia but was decreased on day 4, at a time when local kynurenic acid levels were unchanged. A putative precursor of QUIN, [13C6]anthranilic acid, was not converted to [13C6]‐QUIN in the hippocampus of either normal or 4‐day postischemic gerbils. Gerbil macrophages stimulated by endo‐toxin in vitro converted l‐[13C6]tryptophan to [13Ce]QUIN. Kinetic analysis of kynurenine‐3‐hydroxylase activity in the cerebral cortex of postischemic gerbils showed that Vmax increased, without changes in Km. Systemic administration of pokeweed mitogen increased indoleamine‐2,3‐dioxygenase and kynureninase activities in the brain without significant changes in kynurenine‐3‐hydroxylase or 3‐hydroxyanthranilate‐3,4‐dioxygenase activities. Increases in kynurenine‐3‐hydroxylase activity, in conjunction with induction of indoleamine‐2,3‐dioxygenase, kynureninase, and 3‐hydroxyanthranilate‐3,4‐dioxygenase in macro‐phage infiltrates at the site of brain injury, may explain the ability of postischemic hippocampus to convert l‐[13C6]tryptophan to [13C6]QUIN.

Original languageEnglish
Pages (from-to)2061-2070
Number of pages10
JournalJournal of Neurochemistry
Volume61
Issue number6
DOIs
Publication statusPublished - 01-01-1993
Externally publishedYes

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Quinolinic Acid
Kynurenine
Brain Injuries
Brain
Chemical activation
kynureninase
Gerbillinae
Enzymes
Hippocampus
Pokeweed Mitogens
Tryptophan
Macrophages
kynurenine-oxoglutarate transaminase
Ischemia
Kynurenic Acid
Transient Ischemic Attack
Brain Ischemia
Endotoxins
Cerebral Cortex
Tissue

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Saito, Kuniaki ; Nowak, Thaddeus S. ; Suyama, Kazuhiko ; Quearry, Bonnie J. ; Saito, Misato ; Crowley, Jeffrey S. ; Markey, Sanford P. ; Heyes, Melvyn P. / Kynurenine Pathway Enzymes in Brain : Responses to Ischemic Brain Injury Versus Systemic Immune Activation. In: Journal of Neurochemistry. 1993 ; Vol. 61, No. 6. pp. 2061-2070.
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Saito, K, Nowak, TS, Suyama, K, Quearry, BJ, Saito, M, Crowley, JS, Markey, SP & Heyes, MP 1993, 'Kynurenine Pathway Enzymes in Brain: Responses to Ischemic Brain Injury Versus Systemic Immune Activation', Journal of Neurochemistry, vol. 61, no. 6, pp. 2061-2070. https://doi.org/10.1111/j.1471-4159.1993.tb07443.x

Kynurenine Pathway Enzymes in Brain : Responses to Ischemic Brain Injury Versus Systemic Immune Activation. / Saito, Kuniaki; Nowak, Thaddeus S.; Suyama, Kazuhiko; Quearry, Bonnie J.; Saito, Misato; Crowley, Jeffrey S.; Markey, Sanford P.; Heyes, Melvyn P.

In: Journal of Neurochemistry, Vol. 61, No. 6, 01.01.1993, p. 2061-2070.

Research output: Contribution to journalArticle

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AU - Saito, Kuniaki

AU - Nowak, Thaddeus S.

AU - Suyama, Kazuhiko

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N2 - Accumulation of l‐kynurenine and quinolinic acid (QUIN) in the brain occurs after either ischemic brain injury or after systemic administration of pokeweed mitogen. Although conversion of l‐[13C6]tryptophan to [13C6]‐QUIN has not been demonstrated in brain either from normal gerbils or from gerbils given pokeweed mitogen, direct conversion in brain tissue does occur 4 days after transient cerebral ischemia. Increased activities of enzymes distal to indoleamine‐2,3‐dioxygenase may determine whether l‐kynurenine is converted to QUIN. One day after 10 min of cerebral ischemia, the activities of kynureninase and 3‐hydroxy‐3,4‐dioxygenase were increased in the hippocampus, but local QUIN levels and the activities of the indoleamine‐2,3‐dioxygenase and kynurenine‐3‐hydroxylase were unchanged. By days 2 and 4 after ischemia, however, the activities of all of these enzymes in the hippocampus as well as QUIN levels were significantly increased. Kynurenine aminotransferase activity in the hippocampus was unchanged on days 1 and 2 after ischemia but was decreased on day 4, at a time when local kynurenic acid levels were unchanged. A putative precursor of QUIN, [13C6]anthranilic acid, was not converted to [13C6]‐QUIN in the hippocampus of either normal or 4‐day postischemic gerbils. Gerbil macrophages stimulated by endo‐toxin in vitro converted l‐[13C6]tryptophan to [13Ce]QUIN. Kinetic analysis of kynurenine‐3‐hydroxylase activity in the cerebral cortex of postischemic gerbils showed that Vmax increased, without changes in Km. Systemic administration of pokeweed mitogen increased indoleamine‐2,3‐dioxygenase and kynureninase activities in the brain without significant changes in kynurenine‐3‐hydroxylase or 3‐hydroxyanthranilate‐3,4‐dioxygenase activities. Increases in kynurenine‐3‐hydroxylase activity, in conjunction with induction of indoleamine‐2,3‐dioxygenase, kynureninase, and 3‐hydroxyanthranilate‐3,4‐dioxygenase in macro‐phage infiltrates at the site of brain injury, may explain the ability of postischemic hippocampus to convert l‐[13C6]tryptophan to [13C6]QUIN.

AB - Accumulation of l‐kynurenine and quinolinic acid (QUIN) in the brain occurs after either ischemic brain injury or after systemic administration of pokeweed mitogen. Although conversion of l‐[13C6]tryptophan to [13C6]‐QUIN has not been demonstrated in brain either from normal gerbils or from gerbils given pokeweed mitogen, direct conversion in brain tissue does occur 4 days after transient cerebral ischemia. Increased activities of enzymes distal to indoleamine‐2,3‐dioxygenase may determine whether l‐kynurenine is converted to QUIN. One day after 10 min of cerebral ischemia, the activities of kynureninase and 3‐hydroxy‐3,4‐dioxygenase were increased in the hippocampus, but local QUIN levels and the activities of the indoleamine‐2,3‐dioxygenase and kynurenine‐3‐hydroxylase were unchanged. By days 2 and 4 after ischemia, however, the activities of all of these enzymes in the hippocampus as well as QUIN levels were significantly increased. Kynurenine aminotransferase activity in the hippocampus was unchanged on days 1 and 2 after ischemia but was decreased on day 4, at a time when local kynurenic acid levels were unchanged. A putative precursor of QUIN, [13C6]anthranilic acid, was not converted to [13C6]‐QUIN in the hippocampus of either normal or 4‐day postischemic gerbils. Gerbil macrophages stimulated by endo‐toxin in vitro converted l‐[13C6]tryptophan to [13Ce]QUIN. Kinetic analysis of kynurenine‐3‐hydroxylase activity in the cerebral cortex of postischemic gerbils showed that Vmax increased, without changes in Km. Systemic administration of pokeweed mitogen increased indoleamine‐2,3‐dioxygenase and kynureninase activities in the brain without significant changes in kynurenine‐3‐hydroxylase or 3‐hydroxyanthranilate‐3,4‐dioxygenase activities. Increases in kynurenine‐3‐hydroxylase activity, in conjunction with induction of indoleamine‐2,3‐dioxygenase, kynureninase, and 3‐hydroxyanthranilate‐3,4‐dioxygenase in macro‐phage infiltrates at the site of brain injury, may explain the ability of postischemic hippocampus to convert l‐[13C6]tryptophan to [13C6]QUIN.

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