EDITING OF GLUR2 RNA IN THE GERBIL HIPPOCAMPUS AFTER GLOBAL CEREBRAL-ISCHEMIA

Postischemic delayed neuronal death (DND) in CA1 of the gerbil hippoca mpus is thought to be caused by an abnormal increase of Ca2+ influx in to the cell, mediated by excessive activation of glutamate receptors. One subtype of glutamate receptors, the AMPA receptor, is not permeabl e to calcium ions as long as an edited form of its GluR2 subunit is pr esent. It is possible that global ischemia interferes with the posttra nscriptional editing of the GluR2 mRNA and thus leads to calcium influ x via the AMPA receptor. In order to test this hypothesis, we examined the extent of GluR2 RNA editing in CA1 and CA3 microdissected from ge rbil hippocampus after 5 min of global ischemia and various recirculat ion intervals. At each interval tested, quality and quantity of mRNA e diting in the vulnerable CA1 region were the same as in CA3. Furthermo re. postischemic mRNA editing in both hippocampal regions was indistin guishable from editing in untreated control animals. Our results clear ly demonstrate that global ischemia does not cause impairment of GluR2 RNA editing, which is thus not responsible for the abnormal calcium p ermeability of the postischemic cell membrane.