Astroglial excitability and gliotransmission: An appraisal of Ca 2+ as a signalling route

Robert Zorec, Alfonso Araque, Giorgio Carmignoto, Philip G. Haydon, Alexei Verkhratsky, Vladimir Parpura

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Astroglial cells, due to their passive electrical properties, were long considered subservient to neurons and to merely provide the framework and metabolic support of the brain. Although astrocytes do play such structural and housekeeping roles in the brain, these glial cells also contribute to the brain's computational power and behavioural output. These more active functions are endowed by the Ca 2+-based excitability displayed by astrocytes. An increase in cytosolic Ca 2+ levels in astrocytes can lead to the release of signaling molecules, a process termed gliotransmission, via the process of regulated exocytosis. Dynamic components of astrocytic exocytosis include the vesicular-plasma membrane secretory machinery, as well as the vesicular traffic, which is governed not only by general cytoskeletal elements but also by astrocyte-specific IFs (intermediate filaments). Gliotransmitters released into the ECS (extracellular space) can exert their actions on neighbouring neurons, to modulate synaptic transmission and plasticity, and to affect behaviour by modulating the sleep homoeostat. Besides these novel physiological roles, astrocytic Ca 2+ dynamics, Ca 2+-dependent gliotransmission and astrocyte-neuron signalling have been also implicated in brain disorders, such as epilepsy. The aim of this review is to highlight the newer findings concerning Ca 2+ signalling in astrocytes and exocytotic gliotransmission. For this we report on Ca 2+ sources and sinks that are necessary and sufficient for regulating the exocytotic release of gliotransmitters and discuss secretory machinery, secretory vesicles and vesicle mobility regulation. Finally, we consider the exocytotic gliotransmission in the modulation of synaptic transmission and plasticity, as well as the astrocytic contribution to sleep behaviour and epilepsy. © 2012 The Author(s).
    Original languageEnglish
    Pages (from-to)103-119
    Number of pages16
    JournalASN Neuro
    Volume4
    Issue number2
    DOIs
    Publication statusPublished - 2012

    Keywords

    • Astrocyte
    • Epilepsy
    • Exocytosis
    • Sleep
    • Synaptic transmission
    • Traffic

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