The Journal of Neuroscience, June 15, 2001, 21(12):4237-4248
AMPA/Kainate Receptor Activation Mediates Hypoxic Oligodendrocyte
Death and Axonal Injury in Cerebral White Matter
Selva Baltan
Tekkök and
Mark
P.
Goldberg
Department of Neurology, Center for the Study of Nervous System
Injury, Washington University, St. Louis, Missouri 63110-1193
We developed an in situ model to investigate the
hypothesis that AMPA/kainate (AMPA/KA) receptor activation contributes
to hypoxic-ischemic white matter injury in the adult brain. Acute coronal brain slices, including corpus callosum, were prepared from
adult mice. After exposure to transient oxygen and glucose deprivation
(OGD), white matter injury was assessed by electrophysiology and
immunofluorescence for oligodendrocytes and axonal neurofilaments. White matter cellular components and the stimulus-evoked compound action potential (CAP) remained stable for 12 hr after preparation. OGD
for 30 min resulted in an irreversible loss of the CAP as well as
structural disruption of axons and subsequent loss of neurofilament
immunofluorescence. OGD also caused widespread oligodendrocyte death,
demonstrated by the loss of APC labeling and the gain of pyknotic
nuclear morphology and propidium iodide labeling. Blockade of AMPA/KA
receptors with 30 µM NBQX or the AMPA-selective
antagonist 30 µM GYKI 52466 prevented OGD-induced
oligodendrocyte death. Oligodendrocytes also were preserved by
the removal of Ca2+, but not by a blockade of
voltage-gated Na+ channels. The protective action of
NBQX was still present in isolated corpus callosum slices. CAP areas
and axonal structure were preserved by Ca2+ removal
and partially protected by a blockade of voltage-gated Na+ channels. NBQX prevented OGD-induced CAP loss
and preserved axonal structure. These observations highlight convergent
pathways leading to hypoxic-ischemic damage of cerebral white matter.
In accordance with previous suggestions, the activation of
voltage-gated Na+ channels contributes to axonal
damage. Overactivation of glial AMPA/KA receptors leads to
oligodendrocyte death and also plays an important role in structural
and functional disruption of axons.
Key words:
oligodendrocyte; white matter injury; AMPA/kainate
receptors; axonal injury; brain slices; compound action potential; ischemia; glutamate
Copyright © 2001 Society for Neuroscience 0270-6474/01/21124237-12$05.00/0