Kynurenine pathway enzymes in a rat model of chronic epilepsy: Immunohistochemical study of activated glial cells

doi:10.1016/0306-4522(93)90312-4

Neuroscience

Volume 55, Issue 4, August 1993, Pages 975-989

https://doi.org/10.1016/0306-4522(93)90312-4 Get rights and content

Abstract

The kynurenine pathway metabolites quinolinic acid and kynurenic acid have been hypothetically linked to the occurrence of seizure phenomena. The present immunohistochemical study reports the activation of astrocytes containing three enzymes responsible for the metabolism of quinolinic acid and kynurenic acid in a rat model of chronic epilepsy. Rats received 90 min of patterned electrical stimulation through a bipolar electrode stereotaxically positioned in one hippocampus. This treatment induces non-convulsive limbic status epilepticus that leads to chronic, spontaneous, recurrent seizures. One month after the status epilepticus, the rats showed neuronal loss and gliosis in the piriform cortex, thalamus, and hippocampus, particularly on the side contralateral to the stimulation. Astrocytes containing the kynurenic acid biosynthetic enzyme (kynurenine aminotransferase) and the enzymes for the biosynthesis and degradation of quinolinic acid (3-hydroxyanthranilic acid oxygenase and quinolinic acid phosphoribosyltransferase, respectively) became highly hypertrophied in brain areas where neurodegeneration occurred. Detailed qualitative and quantitative analyses were performed in the hippocampus. In CA1 and CA3 regions, the immunostained surface area of reactive astrocytes increased up to five-fold as compared to controls. Enlarged cells containing the three enzymes were mainly observed in the stratum radiatum, whereas the stratum pyramidale, in which neuronal somata degenerated, showed relatively fewer reactive glial cells. Hypertrophied kynurenine aminotransferase- and 3-hydroxyanthranilic acid oxygenase-immunoreactive cells were comparable in their morphology and distribution pattern. In contrast, reactive quinolinic acid phosphoribosyl transferase-positive glial cells displayed diversified sizes and shapes. Some very large quinolinic acid phosphoribosyl transferase-immunoreactive cells were noticed in the molecular layer of the dentate gyrus. In the hippocampus, the number of immunoreactive glial cells increased in parallel to the hypertrophic responses. In addition, pronounced increases in immunoreactivities, associated with hypertrophied astrocytes, occurred around lesioned sites in the thalamus and piriform cortex.

These findings indicate that kynurenine metabolites derived from glial cells may play a role in chronic epileptogenesis.

Reference (63)

Ben-AriY.
Limbic seizure and brain damage produced by kainic acid: mechanisms and relevance to human temporal lobe epilepsy
Neuroscience
(1985)
CavalheiroE.A. et al.
Long-term effects of intrahippocampal kainic acid injection in rats: a method for inducing spontaneous recurrent seizures
EEC clin. Neurophysiol.
(1982)
DingledineR. et al.
Excitatory amino acid receptors in epilepsy
Trends pharmac. Sci.
(1990)
DuF. et al.
Aminooxyacetic acid causes selective neuronal loss in layer III of the rat medial entorhinal cortex
Neurosci. Lett.
(1992)
EngL.F. et al.
An acidic protein isolated from fibrous astrocytes
Brain Res.
(1971)
FosterA.C. et al.
Kynurenic acid blocks neurotoxicity and seizures induced in rats by the related brain metabolite quinolinic acid
Neurosci. Lett.
(1984)
HansenA. et al.
Hippocampal kindling alters the concentration of glial fibrillary acidic protein and other marker proteins in rat brain
Brain Res.
(1990)
KhurgelM. et al.
Kindling causes changes in the composition of the astrocytic cytoskeleton
Brain Res.
(1992)
KöhlerC. et al.
Localization of quinolinic acid metabolizing enzymes in the rat brain. Immunohistochemical studies using antibodies to 3-hydroxyanthranilic acid oxygenase and quinolinic acid phosphoribosyltransferase
Neuroscience
(1988)
LothmanE.W. et al.
Self-sustaining limbic status epilepticus induced by ‘continuous’ hippocampal stimulation: electrographic and behavioral characteristics
Epilepsy Res.
(1989)

LothmanE.W. et al.

Recurrent hippocampal seizures in the rat as a chronic sequela to limbic status epilepticus

Epilepsy Res.

(1990)

LothmanE.W. et al.

Functional anatomy of hippocampal seizures

Prog. Neurobiol.

(1991)

LothmanE.W. et al.

Kainic acid induced limbic seizures: metabolic, behavioral, electroencephalographic and neuropathological correlates

Brain Res.

(1981)

McMasterO.G. et al.

Focal injection of aminooxyacetic acid produces seizures and lesions in rat hippocampus: evidence for mediation by NMDA receptors

Expl Neurol.

(1991)

NakanoK. et al.

Abnormally high activity of 3-hydroxyanthranilate 3,4-dioxygenase in brain of epilepsy-prone El mice

Brain Res.

(1992)

OkunoE. et al.

Purification and characterization of kynurenine-pyruvate aminotransferase from rat kidney and brain

Brain Res.

(1990)

OkunoE. et al.

Purification of quinolinic acid phosphoribosyltransferase from rat liver and brain

Biochim. biophys. Acta

(1985)

PerkinsM.N. et al.

An iontophoretic investigation of the actions of convulsant kynurenines and their interaction with the endogenous excitant quinolinic acid

Brain Res.

(1982)

SchwarczR. et al.

Excitotoxic models for neurodegenerative disorders

Life Sci.

(1984)

SchwarczR. et al.

Seizure activity and lesions after intrahippocampal quinolinic acid injection

Expl Neurol.

(1984)

SpecialeC. et al.

Increased quinolinic acid metabolism following neuronal degeneration in the rat hippocampus

Brain Res.

(1987)

SperkG. et al.

Kainic acid induced seizures: neurochemical and histopathological changes

Neuroscience

(1983)

SperkG. et al.

Kainic acid-induced seizures: dose-relationship of behavioural, neurochemical and histopathological changes

Brain Res.

(1985)

StoneT.W. et al.

Quinolinic acid: a potent endogenous excitant at amino acid receptors in CNS

Eur. J. Pharmac.

(1981)

Tiffany-CastiglioniE. et al.

Astrocytes in epilepsy

TurskiW.A. et al.

Seizures produced by pilocarpine in mice: a behavioral, electroencephalographic and morphological analysis

Brain Res.

(1984)

WalshJ.L. et al.

4-Halo-3-hydroxyanthranilic acids: potent competitive inhibitors of 3-hydroxyanthranilic acid oxygenase in vitro

Biochem. Pharmac.

(1991)

WalzW.

Role of glial cells in the regulation of the brain ion microenvironment

Prog. Neurobiol.

(1989)

AtilloA. et al.

Pathogenesis of brain lesions caused by experimental epilepsy: light- and electron- microscopic changes in the rat hippocampus following bicuculline-induced status epilepticus

Acta neuropath., Berlin

(1983)

BertramE.H. et al.

The hippocampus in experimental chronic epilepsy: a morphometric analysis

Ann. Neurol.

(1990)

BrotchiJ.

Astrocytes activés etépilepsies focales:étude histoenzymologique

Acta neurol., belgium

(1979)

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Kynurenine pathway enzymes in a rat model of chronic epilepsy: Immunohistochemical study of activated glial cells

Abstract

Neuroscience

EEC clin. Neurophysiol.

Trends pharmac. Sci.

Neurosci. Lett.

Brain Res.

Neurosci. Lett.

Brain Res.

Brain Res.

Neuroscience

Epilepsy Res.

Epilepsy Res.

Prog. Neurobiol.

Brain Res.

Expl Neurol.

Brain Res.

Brain Res.

Biochim. biophys. Acta

Brain Res.

Life Sci.

Expl Neurol.

Brain Res.

Neuroscience

Brain Res.

Eur. J. Pharmac.

Brain Res.

Biochem. Pharmac.

Prog. Neurobiol.

Pathogenesis of brain lesions caused by experimental epilepsy: light- and electron- microscopic changes in the rat hippocampus following bicuculline-induced status epilepticus

Acta neuropath., Berlin

The hippocampus in experimental chronic epilepsy: a morphometric analysis

Ann. Neurol.

Astrocytes activés etépilepsies focales:étude histoenzymologique

Acta neurol., belgium