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65 Developmental regulation of the toxin sensitivity of Ca 2+ permeable ampa receptors in cortical glia
Author(s) -
Meucci Olimpia,
Miller Richard J.
Publication year - 1996
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(96)80260-7
Subject(s) - ampa receptor , miller , neuroscience , citation , glioblastoma , receptor , psychology , library science , medicine , biology , computer science , glutamate receptor , ecology , cancer research
We examined the properties of glutamate agonist-induced Ca*+ fluxes in cultured CG-4 and O-2A progenitor cells from rat cortex. Kainate-induced Ca*+ fluxes in these ceils were found to be attributable to the activation of AMPA receptors. Thus, these fluxes were enhanced by cyclothiazide but not by concanavalin A and were blocked completely by GYKI- 53655. We simultaneously examined kainate-induced Ca'+ entry and Nat currents in these cells under voltage-clamp conditions. Both of these parameters were blocked by Joro spider toxin (JSTx) in undifferentiated cells. However, neither JSTx nor Argiotoxin 636 effectively blocked either parameter in cells differentiated into type II astrocytes. This change in toxin sensitivity occurred slowly over a period of several days. Similar results were obtained in Ca'+-imaging studies. When cells were differentiated into oligodendrocytes, they showed an intermediate sensitivity to block by JSTx as assessed using imaging and voltage-clamp studies. Analysis of the expression of AMPA-receptor subunits showed an increase in the concentration of glutamate receptor-2 (GluR2) in CG-4 cells as they differentiated into type II astro- cytes and oligodendrocytes. These results demonstrate that the AMPA receptors in cells of the O-2A lineage flux appre- ciable amounts of Ca*+ but may contain variable amounts of edited GluR2 subunits.