Oligodendrocyte excitotoxicity determined by local glutamate accumulation and mitochondrial function

Wenbin Deng, Qin Yue, Paul A. Rosenberg, Joseph J. Volpe, Frances E. Jensen

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Developing oligodendrocytes (OL precursors, pre-OLs) express α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype glutamate receptors (AMPARs) and are highly vulnerable to hypoxic-ischemic or oxygen-glucose deprivation (OGD)-induced excitotoxic injury, yet the mechanisms of injury remain unclear. Here we investigated the role of glutamate accumulation and mitochondrial function in OGD-induced pre-OL toxicity in vitro. Bulk glutamate concentration in the culture medium did not increase during OGD and OGD-conditioned medium did not transfer toxicity to naïve cells. Facilitation of glutamate diffusion by constant agitation of the culture reduced, while inhibition of glutamate diffusion by increasing medium viscosity with dextran enhanced, OGD-induced pre-OL injury. Depletion of extracellular glutamate by the glutamate scavenging system, glutamate-pyruvate transaminase plus pyruvate, attenuated pre-OL injury during OGD. Together these data suggest that local glutamate accumulation is critical for OGD toxicity. Interestingly, under normoxic conditions, addition of glutamate to pre-OLs did not cause receptor-mediated toxicity, but the toxicity could be unmasked by mitochondrial impairment with mitochondrial toxins. Furthermore, OGD caused mitochondrial potential collapse that was independent of AMPAR activation, and OGD toxicity was enhanced by mitochondrial toxins. These data demonstrate that pre-OL excitotoxicity is exacerbated by mitochondrial dysfunction during OGD. Overall, our results indicate that OGD-induced pre-OL injury is a novel form of excitotoxicity caused by the combination of local glutamate accumulation that occurs without an increase in bulk glutamate concentration and mitochondrial dysfunction. Therapeutic strategies targeting local glutamate concentration and mitochondrial injury during hypoxia-ischemia may be relevant to human disorders associated with pre-OL excitotoxicity.

Original languageEnglish (US)
Pages (from-to)213-222
Number of pages10
JournalJournal of Neurochemistry
Volume98
Issue number1
DOIs
StatePublished - Jul 2006
Externally publishedYes

Fingerprint

Oligodendroglia
Glutamic Acid
Oxygen
Glucose
Toxicity
Wounds and Injuries
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
Glutamate Receptors
Pyruvic Acid
Scavenging
Conditioned Culture Medium
Transaminases
Dextrans
Viscosity
Culture Media
Ischemia
Chemical activation

Keywords

  • AMPA receptor
  • Excitotoxicity
  • Glutamate
  • Mitochondria
  • Oligodendrocyte
  • Oxygen-glucose deprivation
  • Periventricular leukomalacia

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Oligodendrocyte excitotoxicity determined by local glutamate accumulation and mitochondrial function. / Deng, Wenbin; Yue, Qin; Rosenberg, Paul A.; Volpe, Joseph J.; Jensen, Frances E.

In: Journal of Neurochemistry, Vol. 98, No. 1, 07.2006, p. 213-222.

Research output: Contribution to journalArticle

Deng, Wenbin ; Yue, Qin ; Rosenberg, Paul A. ; Volpe, Joseph J. ; Jensen, Frances E. / Oligodendrocyte excitotoxicity determined by local glutamate accumulation and mitochondrial function. In: Journal of Neurochemistry. 2006 ; Vol. 98, No. 1. pp. 213-222.
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