title: What do we know about gliotransmitter release from astrocytes?
abstract: Astrocytes participate in information processing by actively modulating synaptic properties via gliotransmitter release. Various mechanisms of astrocytic release have been reported, including release from storage organelles via exocytosis and release from the cytosol via plasma membrane ion channels and pumps. It is still not fully clear which mechanisms operate under which conditions, but some of them, being Ca(2+)-regulated, may be physiologically relevant. The properties of Ca(2+)-dependent transmitter release via exocytosis or via ion channels are different and expected to produce different extracellular transmitter concentrations over time and to have distinct functional consequences. The molecular aspects of these two release pathways are still under active investigation. Here, we discuss the existing morphological and functional evidence in support of either of them. Transgenic mouse models, specific antagonists and localization studies have provided insight into regulated exocytosis, albeit not in a systematic fashion. Even more remains to be uncovered about the details of channel-mediated release. Better functional tools and improved ultrastructural approaches are needed in order fully to define specific modalities and effects of astrocytic gliotransmitter release pathways.
authors.affiliation: Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland daniela.sahlender@unil.ch.
authors.forename: Daniela A
authors.identifier: http://orcid.org/0000-0002-0510-9529
authors.initials: DA
authors.lastname: Sahlender
authors.affiliation: Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland isavtcho@unil.ch.
authors.forename: Iaroslav
authors.identifier: http://orcid.org/0000-0001-8197-7232
authors.initials: I
authors.lastname: Savtchouk
authors.affiliation: Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland andrea.volterra@unil.ch.
authors.forename: Andrea
authors.initials: A
authors.lastname: Volterra
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000502:physiology*; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D018377:Neurotransmitter Agents / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D018377:Neurotransmitter Agents
keywords: astrocytes; channels; electron microscopy; gliotransmission; glutamate; regulated exocytosis