title: Calcium-induced calcium release and gap junctions mediate large-scale calcium waves in olfactory ensheathing cells in situ.
abstract: Olfactory ensheathing cells (OECs) are a specialised type of glial cells, supporting axon growth and guidance during development and regeneration of the olfactory nerve and the nerve layer of the olfactory bulb. We measured calcium signalling in OECs in olfactory bulb in-toto preparations using confocal and epifluorescence microscopy and the calcium indicator Fluo-4. We identified two subpopulations of olfactory bulb OECs: OECs in the outer sublamina of the nerve layer responded to purinergic neurotransmitters such as adenosine triphosphate with calcium transients, while OECs in the inner sublamina of the nerve layer did not respond to neurotransmitters. However, the latter generated spontaneous calcium waves that covered hundreds of cells. These calcium waves persisted in the presence of tetrodotoxin and in calcium-free saline, but were abolished after calcium store depletion with cyclopiazonic acid or inositol trisphosphate receptor blockage with 2-APB. Calcium waves could be triggered by laser photolysis of caged inositol trisphosphate. Blocking purinoceptors with PPADS had no effect on calcium wave propagation, whereas blocking gap junctions with carbenoxolone or meclofenamic acid entirely suppressed calcium waves. Increasing calcium buffer capacity in OECs with NP-EGTA ("caged" Ca(2+)) prevented calcium wave generation, and laser photolysis of NP-EGTA in a small group of OECs resulted in a calcium increase in the irradiated cells followed by a calcium wave. We conclude that calcium waves in OECs can be initiated by calcium-induced calcium release via InsP3 receptors and propagate through gap junctions, while purinergic signalling is not involved.
authors.affiliation: Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Kaiserslautern, Germany; Graduiertenkolleg 845, Universität Kaiserslautern, Kaiserslautern, Germany; Abteilung Neurophysiologie, Universität Hamburg, Hamburg, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Stavermann
authors.affiliation: Klinik für Allgemeine Neurologie, Universitätsklinikum Münster, Münster, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Meuth
authors.affiliation: Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Doengi
authors.affiliation: Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Thyssen
authors.affiliation: Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Kaiserslautern, Germany; Graduiertenkolleg 845, Universität Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Joachim W
authors.initials: JW
authors.lastname: Deitmer
authors.affiliation: Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Kaiserslautern, Germany; Graduiertenkolleg 845, Universität Kaiserslautern, Kaiserslautern, Germany; Abteilung Neurophysiologie, Universität Hamburg, Hamburg, Germany. Electronic address: christian.lohr@uni-hamburg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Lohr
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D017629:Gap Junctions / Q000378:metabolism*; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D009830:Olfactory Bulb / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014966:Xanthenes / Q000737:chemistry / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; D001896:Boron Compounds; C409648:Fluo 4; D007211:Indoles; D053496:Inositol 1,4,5-Trisphosphate Receptors; D014966:Xanthenes; C085112:2-nitrophenyl-EGTA; D013779:Tetrodotoxin; D004533:Egtazic Acid; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium; C000543:cyclopiazonic acid
keywords: Calcium waves; Gap junctions; Glial cells; Olfactory bulb