AMPA/kainate receptor activation in murine oligodendrocyte precursor cells leads to activation of a cation conductance, calcium influx and blockade of delayed rectifying K+ channels

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Item Type:	Article
Title:	AMPA/kainate receptor activation in murine oligodendrocyte precursor cells leads to activation of a cation conductance, calcium influx and blockade of delayed rectifying K+ channels
Creators Name:	Borges, K., Ohlemeyer, C., Trotter, J. and Kettenmann, H.
Abstract:	Studies during the last few years have shown that glial cells can express a large repertoire of neurotransmitter receptors. In this study, we have characterized the properties of a glutamate receptor in oligodendrocytes and their precursor cells from cultures of mouse brain, using the patch-clamp technique to measure ligand-activated currents and a fura-2 imaging system to determine changes in free cytosolic Ca2+ concentration ([Ca2+]i). The precursor cells were identified by their characteristic morphology and their voltage-gated currents as described previously [Sontheimer H. et al. (1989) Neuron 2, 1135-1145]. The ligands kainate, domoate and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA), as well as L-glutamate but not trans-1-amino-1,3-cyclopentanedicarboxylate elicited inward currents at a holding potential of -70 mV and the antagonist 6-cyano-7-nitroquinoxaline-2,3-dione blocked the glutamate- and kainate-induced response reversibly, indicating the expression of an AMPA/kainate-type glutamate receptor. The response is due to the activation of a cationic conductance as revealed by analysing the reversal potential of the kainate-activated current. Receptor activation is accompanied by two additional responses: (i) an increase in [Ca2+]i mediated by depolarization and a subsequent activation of voltage-gated Ca2+ channels and (ii) a transient blockade of a delayed rectifying K+ current, but not of the A-type K+ current. The blockade of the K+ current was not due to the increase in [Ca2+]i since it was also observed in Ca(2+)-free bathing solution when no increase in [Ca2+]i was detectable after exposure to kainate. In contrast to precursor cells, oligodendrocytes responded weakly or not at all to glutamate or related ligands. We conclude that glutamate activates a complex pattern of physiological events in the glial precursor cells, which may play a role during the differentiation process of these cells.
Keywords:	AMPA Receptors, Calcium Channels, Cations, Cell Differentiation, Drug Dose-Response Relationship, Electrophysiology, Excitatory Amino Acid Agonists, Excitatory Amino Acid Antagonists, Kainic Acid, Kainic Acid Receptors, Membrane Potentials, Oligodendroglia, Patch-Clamp Techniques, Potassium Channels, Animals, Mice
Source:	Neuroscience
ISSN:	0306-4522
Publisher:	Elsevier
Volume:	63
Number:	1
Page Range:	135-149
Date:	1 November 1994
Official Publication:	https://doi.org/10.1016/0306-4522(94)90012-4
PubMed:	View item in PubMed

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