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Title: Hypoxia–ischemia preferentially triggers glutamate depletion from oligodendroglia and axons in perinatal cerebral white matter
Authors: Back, Stephen A.
Craig, Andrew
Kayton, Robert J.
Luo, Ning Ling
Meshul, Charles K.
Allcock, Natalie
Fern, Robert
First Published: 7-Jun-2006
Publisher: Nature Publishing Group
Citation: Journal of Cerebral Blood Flow & Metabolism, 2007, 27 (2), pp. 334–347
Abstract: Ischemia is implicated in periventricular white matter injury (PWMI), a lesion associated with cerebral palsy. PWMI features selective damage to early cells of the oligodendrocyte lineage, a phenomenon associated with glutamate receptor activation. We have investigated the distribution of glutamate in rat periventricular white matter at post-natal day 7. Immuno-electron microcopy was used to identify O4(+) oligodendroglia in control rats, and a similar approach was employed to stain glutamate in these cells before and after 90 mins of hypoxia–ischemia. This relatively brief period of hypoxia–ischemia produced mild cell injury, corresponding to the early stages of PWMI. Glutamate-like reactivity was higher in oligodendrocytes than in other cell types (2.13±0.25 counts/µm2), and declined significantly during hypoxia–ischemia (0.93±0.15 counts/µm2: P<0.001). Astrocytes had lower glutamate levels (0.7±0.07 counts/µm2), and showed a relatively small decline during hypoxia–ischemia. Axonal regions contained high levels of glutamate (1.84±0.20 counts/µm2), much of which was lost during hypoxia–ischemia (0.72±0.20 counts/µm2: P>0.001). These findings suggest that oligodendroglia and axons are the major source of extracellular glutamate in developing white matter during hypoxia–ischemia, and that astrocytes fail to accumulate the glutamate lost from these sources. We also examined glutamate levels in the choroid plexus. Control glutamate levels were high in both choroid epithelial (1.90±0.20 counts/µm2), and ependymal cells (2.20±0.28 counts/µm2), and hypoxia–ischemia produced a large fall in ependymal glutamate (0.97±0.08 counts/µm2: P>0.001). The ependymal cells were damaged by the insult and represent a further potential source of glutamate during ischemia.
DOI Link: 10.1038/sj.jcbfm.9600344
ISSN: 0271-678X
Type: Article
Description: This is the author’s submitted draft of the paper published as Journal of Cerebral Blood Flow & Metabolism, 2007, 27 (2), pp. 334–347. The final published version is available at, Doi: 10.1038/sj.jcbfm.9600344.
Appears in Collections:Published Articles, Dept. of Cell Physiology and Pharmacology

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