AMPA RECEPTORS SHAPE CA2-4 CELLS( RESPONSES IN CORTICAL OLIGODENDROCYTE PROGENITORS AND CG)

Intracellular calcium signals triggered by glutamate receptor activati on were studied in primary cortical oligodendrocyte lineage cells and in the oligodendrocyte cell line CG-4, Glutamate, kainate, and AMPA (3 0-300 mu M) increased [Ca2+](i) in both types of cells at the stage of oligodendrocyte progenitors (O-2A; GD3(+)) or pro-oligodendroblasts ( O4(+)). The peak amplitude of Ca2+ responses to glutamate receptor ago nists was significantly larger in cortical cells. In CG-4 and in corti cal cells, the majority (more than 90%) of bipolar GD3(+) or multipola r O4(+) cells responded to kainate, In all the cells analyzed, kainate was more efficacious than AMPA and glutamate, The percentage of bipol ar or multipolar cells responding to glutamate was significantly lower in the CG-4 cell line than in primary cultures. Cellular responses ty pical of metabotropic glutamate receptor activation were observed in 2 0% of the cortical O-2A progenitors, but in none of the CG-4 cells, Th e AMPA-selective antagonist GYKI 52466 blocked kainate-induced Ca2+ re sponses in cortical O-2A cells, The selective AMPA receptor modulator cyclothiazide (30 mu M) greatly potentiated the effects of AMPA (30-10 0 mu M) on [Ca2+](i) in cortical and CG-4 cells, Our findings indicate that Ca2+ responses in cells of the oligodendrocyte lineage are prima rily shaped by functional AMPA receptors. (C) 1995 Wiley-Liss, Inc.