GLIAL-CELLS OF THE OLIGODENDROCYTE LINEAGE EXPRESS BOTH KAINATE-PREFERRING AND AMPA-PREFERRING SUBTYPES OF GLUTAMATE-RECEPTOR

mRNAs for AMPA- and kainate-preferring glutamate receptor subunits are expressed abundantly in the CNS, yet functional studies of neurons an d glia from brain suggest selective expression of AMPA receptors. We n ow show that glial cells of the O-2A lineage express rapidly desensiti zing responses to kainate, mRNAs for GluR6, GluR7, KA-1, and KA-2, rap idly desensitizing responses to AMPA, and mRNAs for CluR-B, -C, and -D . Analysis of glutamate receptor currents in single cells reveals two receptor populations with high and low affinity for kainate and differ ent sensitivity for potentiation by concanavalin A and for block of de sensitization by cyclothiazide. Our experiments describe the character ization of native kainate-preferring receptors in glia and reveal coex pression in single cells of functional AMPA- and kainate-preferring re ceptors.