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GABA Triggers a [Ca 2+ ] i Increase in Murine Precursor Cells of the Oligodendrocyte Lineage
Author(s) -
Kirchhoff Frank,
Kettenmann Helmut
Publication year - 1992
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1992.tb00131.x
Subject(s) - gabaa receptor , picrotoxin , bicuculline , gabaergic , muscimol , oligodendrocyte , biophysics , gamma aminobutyric acid , microbiology and biotechnology , chemistry , inhibitory postsynaptic potential , neurotransmitter , biology , receptor , neuroscience , biochemistry , central nervous system , myelin
The development of oligodendrocytes from their precursor cells can be studied in vitro by using a culture system in which cells can be identified at different developmental stages. We used this culture system to compare the effect of the inhibitory neurotransmitter γ‐aminobutyric acid (GABA) on intracellular Ca 2+ concentration ([Ca 2+ ] i ) using fura‐2 fluorescence systems. Application of GABA evoked transient [Ca 2+ ] i increases in precursor cells. In contrast, [Ca 2+ ] i levels were not affected in oligodendrocytes, which were identified by their positive labelling with the antibody O1. The precursor cells, identified by a lack of O1 staining, responded to GABA in the concentration range between 10 −6 and 10 −4 M. Since muscimol mimicked and bicuculline as well as picrotoxin blocked the GABA response, we conclude that the response is mediated by activation of GABA A receptors. The involvement of Ca 2+ channels is inferred from the observation that the [Ca 2+ ] i changes could be blocked by nifedipine or by omitting Ca 2+ from the bath solution. Both GABA A receptors and Ca 2+ channels have been previously identified on these precursor cells with the aid of the patch‐clamp technique. We thus propose the following mechanism to explain our observations: the Cl − efflux via the GABA receptor depolarizes precursor cells, and this depolarization leads to activation of Ca 2+ channels, resulting in an influx of Ca 2+ and the observed rise in cytosolic [Ca 2+ ]. Although its physiological importance is speculative, this event could serve as a signal from GABAergic neurons to glial precursor cells.