Sb. Tekkok et Mp. Goldberg, AMPA/Kainate receptor activation mediates hypoxic oligodendrocyte death and axonal injury in cerebral white matter, J NEUROSC, 21(12), 2001, pp. 4237-4248
We developed an in situ model to investigate the hypothesis that AMPA/kaina
te (AMPA/KA) receptor activation contributes to hypoxic-ischemic white matt
er 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 electro
physiology and immunofluorescence for oligodendrocytes and axonal neurofila
ments. White matter cellular components and the stimulus-evoked compound ac
tion potential (CAP) remained stable for 12 hr after preparation. OGD for 3
0 min resulted in an irreversible loss of the CAP as well as structural dis
ruption of axons and subsequent loss of neurofilament immunofluorescence. O
GD also caused widespread oligodendrocyte death, demonstrated by the loss o
f APC labeling and the gain of pyknotic nuclear morphology and propidium io
dide labeling. Blockade of AMPA/KA receptors with 30 muM NBQX or the AMPA-s
elective antagonist 30 mM 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 bloc
kade of voltage-gated Na+ channels. NBQX prevented OGD-induced CAP loss and
preserved axonal structure. These observations highlight convergent pathwa
ys leading to hypoxic-ischemic damage of cerebral white matter. In accordan
ce with previous suggestions, the activation of voltage-gated Na+ channels
contributes to axonal damage. Overactivation of glial AMPA/KA receptors lea
ds to oligodendrocyte death and also plays an important role in structural
and functional disruption of axons.