Excitatory amino acid induced oligodendrocyte cell death in vitro: receptor-dependent and -independent mechanisms

Rosin, Claudia and Bates, Timothy E. and Skaper, Stephen D. (2004) Excitatory amino acid induced oligodendrocyte cell death in vitro: receptor-dependent and -independent mechanisms. Journal of Neurochemistry, 90 (5). pp. 1173-1185. ISSN 0022-3042

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Full text URL: http://dx.doi.org/10.1111/j.1471-4159.2004.02584.x

Abstract

Oligodendroglia play an important role in axonal conduction in the CNS and are sensitive to oxidative toxicity induced by glutamate in the absence of ionotropic glutamate receptors. In this study, oligodendrocyte signalling cascades were examined, in response to glutamate-induced oxidative injury and to excitotoxicity. Rat cortical oligodendrocytes, differentiated in culture, were highly vulnerable to glutamate-induced cell death. Competitive inhibition of cystine uptake and increased oxidative stress appeared responsible for this death, and caused an accumulation of intracellular peroxides as well as chromatin fragmentation and condensation. Glutamate receptor subtype agonists (quisqualate, ibotenate) known to inhibit cystine uptake were cytotoxic, but not NMDA itself; moreover, glutamate receptor antagonists were not protective. Oligodendrocytes were also vulnerable to overactivation of glutamate receptors, as kainic acid and AMPA proved to be toxic. AMPA toxicity required the presence of cyclothiazide, suggesting rapid desensitization of AMPA receptors. Glutamate-induced oxidative stress and kainate/AMPA receptor stimulation activated the mitogen-activated protein kinase (MAP kinase) pathway, as well as the transcription factor ELK. However, MAP kinase kinase inhibitors only protected against injury from glutamate-induced oxidative stress. Oligodendrocytes were sensitive to oxygen-glucose deprivation injury as well, in a MAP kinase dependent fashion. Glutamate toxicity may conceivably be operative in neuropathological conditions that disrupt neuronal/oligodendrocyte interactions in axons, e.g. multiple sclerosis and ischaemia-reperfusion injury.

Item Type:Article
Additional Information:Oligodendroglia play an important role in axonal conduction in the CNS and are sensitive to oxidative toxicity induced by glutamate in the absence of ionotropic glutamate receptors. In this study, oligodendrocyte signalling cascades were examined, in response to glutamate-induced oxidative injury and to excitotoxicity. Rat cortical oligodendrocytes, differentiated in culture, were highly vulnerable to glutamate-induced cell death. Competitive inhibition of cystine uptake and increased oxidative stress appeared responsible for this death, and caused an accumulation of intracellular peroxides as well as chromatin fragmentation and condensation. Glutamate receptor subtype agonists (quisqualate, ibotenate) known to inhibit cystine uptake were cytotoxic, but not NMDA itself; moreover, glutamate receptor antagonists were not protective. Oligodendrocytes were also vulnerable to overactivation of glutamate receptors, as kainic acid and AMPA proved to be toxic. AMPA toxicity required the presence of cyclothiazide, suggesting rapid desensitization of AMPA receptors. Glutamate-induced oxidative stress and kainate/AMPA receptor stimulation activated the mitogen-activated protein kinase (MAP kinase) pathway, as well as the transcription factor ELK. However, MAP kinase kinase inhibitors only protected against injury from glutamate-induced oxidative stress. Oligodendrocytes were sensitive to oxygen-glucose deprivation injury as well, in a MAP kinase dependent fashion. Glutamate toxicity may conceivably be operative in neuropathological conditions that disrupt neuronal/oligodendrocyte interactions in axons, e.g. multiple sclerosis and ischaemia-reperfusion injury.
Keywords:oligodendrocyte, glutamate, oxidative stress, excitotoxicity, Glutamate receptors, kainate, AMPA, multiple sclerosis
Subjects:A Medicine and Dentistry > A100 Pre-clinical Medicine
B Subjects allied to Medicine > B140 Neuroscience
B Subjects allied to Medicine > B200 Pharmacology, Toxicology and Pharmacy
A Medicine and Dentistry > A300 Clinical Medicine
Divisions:College of Science > School of Life Sciences
ID Code:5228
Deposited By: Timothy Bates
Deposited On:27 Jun 2012 17:18
Last Modified:27 Jun 2012 17:18

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