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J Neurosci. 1994 Apr;14(4):1879-91.

Glutamate receptor agonists stimulate diverse calcium responses in different types of cultured rat cortical glial cells.

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  • 1Department of Pharmacological and Physiological Sciences, University of Chicago, Illinois 60637.


We examined the effects of different types of glutamate receptor agonists on the intracellular calcium concentration, ([Ca2+]i), in cultured rat cortical glial cells. The cells in these cultures were characterized immunocytochemically using antibodies against glial fibrillary acidic protein, A2B5, and OX-42. The metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3- dicarboxylic acid produced Ca2+ mobilization from intracellular stores in all classes of cells. Agonists at non-NMDA glutamate receptors also produced large increases in [Ca2+]i, primarily in cells of the O-2A lineage. Disruption of intracellular Ca2+ stores with thapsigargin showed that increases in [Ca2+]i produced by activating AMPA/kainate receptors were primarily due to Ca2+ influx rather than Ca(2+)-induced Ca2+ release. Agonists at NMDA receptors were ineffective. Electrophysiological studies revealed that cells of the O-2A lineage exhibited moderate inward currents in response to kainate in Na(+)-containing solutions, but only small inward currents and outward rectification in Na(+)-free solutions. However, in the presence of cyclothiazide, the kainate-induced currents were increased in size and a rightward shift of the reversal potential with increased [Ca2+]o could be demonstrated. Activation of cells by kainate, but not by depolarizing stimuli, stimulated the uptake of Co2+. Polymerase chain reaction studies showed that the glutamate receptor subunits GluR1-4 and GluR6 were all expressed in these cultures, but GluR5 was absent. The nature of the Ca2+ uptake pathway activated by non-NMDA receptor agonists in the O-2A lineage population is discussed. It is considered most likely that the O-2A lineage cells express both non-NMDA receptors that are relatively impermeable to divalent cations, as well as a smaller population that are Ca2+ permeable.

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