Calcium signalling in mouse Bergmann glial cells mediated by alpha1-adrenoreceptors and H1 histamine receptors.
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 microM) and histamine (10-100 microM) triggered a transient increase in [Ca2+]i. The involvement of the alpha1-adrenoreceptor was inferred from the observations that monoamine-triggered [Ca2+]i responses were locked by the selective alpha1-adreno-antagonist prazosin and were mimicked by the alpha1-adreno-agonist phenylephrine. The monoamine-induced [Ca2+]i signals were not affected by beta- and alpha2-adrenoreceptor antagonists (propranolol and yohimbine), and were not mimicked by beta- and alpha2-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 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 alpha1-adrenoreceptors and H1 histamine receptors which induce the generation of intracellular [Ca2+]i signals via activation of Ca2+ release from inositol-1,4,5-trisphosphate-sensitive intracellular stores.
Kirischuk
S
S
Max-Delbruck Centre for Molecular Medicine, Robert-Rossle Strasse 10, Berlin-Buch, Germany.
Tuschick
S
S
Verkhratsky
A
A
Kettenmann
H
H
D000322:Adrenergic Agonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D004837:Epinephrine / Q000502:physiology; D006632:Histamine / Q000502:physiology; D017442:Histamine Agonists / Q000494:pharmacology; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D051379:Mice; D009457:Neuroglia / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology; D018408:Patch-Clamp Techniques; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000502:physiology*; D017981:Receptors, Neurotransmitter / Q000819:agonists; D015398:Signal Transduction / Q000502:physiology*
D000322:Adrenergic Agonists; D017442:Histamine Agonists; D018340:Receptors, Adrenergic, alpha-1; D011969:Receptors, Histamine H1; D017981:Receptors, Neurotransmitter; D006632:Histamine; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium; D009638:Norepinephrine; D004837:Epinephrine