Calcium Signalling in Mouse Bergmann Glial Cells Mediated by α1-adrenoreceptors and H1 Histamine - Receptors |
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Authors: | Sergej Kirischuk Sebastian Tuschick Alexej Verkhratsky Helmut Kettenmann |
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Affiliation: | Max-Delbrück Centre for Molecular Medicine, Robert-Rössle Strasse 10, Berlin-Buch, Germany |
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Abstract: | The presence of adrenergic and histaminergic receptors in Bergmann glial cells from cerebellar slices from mice aged 20–25 days was determined using fura-2 Ca2+ microfluorimetry. To measure the cytoplasmic concentration of Ca2+ ([Ca2+]i), either individual cells were loaded with the Ca2+-sensitive probe fura-2 using the whole-cell patch-clamp technique or slices were incubated with a membrane-permeable form of the dye (fura-2/AM) and the microfluorimetric system was focused on individual cells. The monoamines adrenalin and noradrenalin (0.1-10 μM) and histamine (10-100 μM) triggered a transient increase in [Ca2+]i. The involvement of the α1-adrenoreceptor was inferred from the observations that monoamine-triggered [Ca2+]i responses were blocked by the selective α1-adreno-antagonist prazosin and were mimicked by the α1-adreno-agonist phenylephrine. The monoamine-induced [Ca2+]i signals were not affected by β- and α2-adrenoreceptor antagonists (propranolol and yohimbine), and were not mimicked by β- and α2-adrenoreceptor agonists (isoproterenol and clonidine). Histamine-induced [Ca2+]i responses demonstrated specific sensitivity to only H1 histamine receptor modulators. [Ca2+]i responses to monoamines and histamine did not require the presence of extracellular Ca2+ and they were blocked by preincubation of slices with thapsigargin (500 nM), indicating that the [Ca2+]i increase is due to release from intracellular pools. No [Ca2+]i responses were recorded after application of aspartate, bradykinin, dopamine, GABA, glycine, oxytocin, serotonin, somatostatin, substance P, taurine or vasopressin. We conclude that cerebellar Bergmann glial cells are endowed with α1 -adrenoreceptors and H1 histamine receptors which induce the generation of intracellular [Ca2+]i signals via activation of Ca2+ release from inositol-l,4,5-trisphosphate-sensitive intracellular stores. |
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Keywords: | Bergmann glia cerebellum calcium neuron-glia interactions α1-adrenoreceptors H1 histamine receptors |
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