AMPA receptor and its role in astroglia

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We have prepared astroglia-rich cultures from the embryonic rat cerebral cortex, and investigated activation of AMPA receptor in astroglia using calcium-imaging. In our culture condition, AMPA receptor-evoked increases in intracellular calcium concentration was observed in a small population of cells. This calcium responses were potentiated by PEPA and cyclothiazide, allosteric potentiators of AMPA receptors, and the extent of potentiation by two drugs depends upon cells. This is probably due to cell-dependent heterogeneity of AMPA receptors. In these cells, membrane currents mediated by AMPA receptors were recorded using patch clamp recordings.The current responses were also potentiated by PEPA, and show inwardly rectifying I-V relation, at least in the cells we tested. We have examined gene expression stimulated by the activation of glial AMPA receptors. For this purpose, quantitative RT-PCR was carried out for mRNA from glial cultures. We could not detect significant increases in expression of GDNF mRNA level in our cultures. We have further investigated on other gene, and prepared glial cells from other brain regions, in order to get further information on glial AMPA receptors.