Radially expanding transglial calcium waves in the intact cerebellum. Proc Natl Acad Sci USA

Department of Molecular Biology and Princeton Neuroscience Institute, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 03/2009; 106(9):3496-501. DOI: 10.1073/pnas.0809269106
Source: PubMed


Multicellular glial calcium waves may locally regulate neural activity or brain energetics. Here, we report a diffusion-driven astrocytic signal in the normal, intact brain that spans many astrocytic processes in a confined volume without fully encompassing any one cell. By using 2-photon microscopy in rodent cerebellar cortex labeled with fluorescent indicator dyes or the calcium-sensor protein G-CaMP2, we discovered spontaneous calcium waves that filled approximately ellipsoidal domains of Bergmann glia processes. Waves spread in 3 dimensions at a speed of 4-11 microm/s to a diameter of approximately 50 microm, slowed during expansion, and were reversibly blocked by P2 receptor antagonists. Consistent with the hypothesis that ATP acts as a diffusible trigger of calcium release waves, local ejection of ATP triggered P2 receptor-mediated waves that were refractory to repeated activation. Transglial waves represent a means for purinergic signals to act with local specificity to modulate activity or energetics in local neural circuits.

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Available from: Werner Göbel, Oct 05, 2015
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    • "Yet, it was later acknowledged that astroglia exhibit a special form of excitability that is based on variations in the intracellular concentration of Ca 2+ ions (Charles et al., 1991; Cornell-Bell et al., 1990). Studies performed in acute brain slices and, more recently, in vivo allowed to determine that astrocytic [Ca 2+ ] i changes can occur spontaneously (Aguado et al., 2002; Hirase et al., 2004; Hoogland et al., 2009; Navarrete et al., 2013; Nett et al., 2002; Nimmerjahn et al., 2009; Panatier et al., 2011; Parri et al., 2001), or can be evoked in response to synaptic activity (Dani et al., 1992; Di Castro et al., 2011; Dombeck et al., 2007; Gourine et al., 2010; Jourdain et al., 2007; Nimmerjahn et al., 2009; Pasti et al., 1997; Paukert et al., 2014; Petzold et al., 2008; Porter and McCarthy, 1995a,b, 1996; Santello et al., 2011; Schummers et al., 2008; Wang et al., 2006; Winship et al., 2007). In addition, there is evidence indicating that they can be mediated also by transient receptor potential A1 channels (Shigetomi et al., 2012, 2013a). "
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    ABSTRACT: Recent breakthroughs in neuroscience have led to the awareness that we should revise our traditional mode of thinking and studying the CNS, i.e. by isolating the privileged network of "intelligent" synaptic contacts. We may instead need to contemplate all the variegate communications occurring between the different neural cell types, and centrally involving the astrocytes. Basically, it appears that a single astrocyte should be considered as a core that receives and integrates information from thousands of synapses, other glial cells and the blood vessels. In turn, it generates complex outputs that control the neural circuitry and coordinate it with the local microcirculation. Astrocytes thus emerge as the possible fulcrum of the functional homeostasis of the healthy CNS. Yet, evidence indicates that the bridging properties of the astrocytes can change in parallel with, or as a result of, the morphological, biochemical and functional alterations these cells undergo upon injury or disease. As a consequence, they have the potential to transform from supportive friends and interactive partners for neurons into noxious foes. In this review, we summarize the currently available knowledge on the contribution of astrocytes to the functioning of the CNS and what goes wrong in various pathological conditions, with a particular focus on amyotrophic lateral sclerosis, Alzheimer's disease and ischemia. The observations described convincingly demonstrate that the development and progression of several neurological disorders involve the de-regulation of a finely tuned interplay between multiple cell populations. Thus, it seems that a better understanding of the mechanisms governing the integrated communication and detrimental responses of the astrocytes as well as their impact towards the homeostasis and performance of the CNS is fundamental to open novel therapeutic perspectives. Copyright © 2015. Published by Elsevier Ltd.
    Progress in Neurobiology 04/2015; 29. DOI:10.1016/j.pneurobio.2015.04.003 · 9.99 Impact Factor
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    • "Since the probability of finding these neurons is relatively low [1 GoC every 430 GrCs (Korbo et al., 1993), 1 Lugaro cell/15 PCs (Dieudonné and Dumoulin, 2000)], it is unlikely that they contributed significantly to signal generation in our recordings. It should also be noted that a contribution of calcium signals generated by glial cells (Hoogland et al., 2009; Hoogland and Kuhn, 2010) cannot be completely ruled out. However, such a contribution is unlikely, given that the typical calcium transients in astrocytes and glial cells show slower kinetics and larger latencies compared with those of neuronal signals and glial calcium waves usually fluctuate independently of synaptic inputs (Hoogland et al., 2009; Hoogland and Kuhn, 2010). "
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    ABSTRACT: In order to investigate the spatiotemporal organization of neuronal activity in local microcircuits, techniques allowing the simultaneous recording from multiple single neurons are required. To this end, we implemented an advanced spatial-light modulator two-photon microscope (SLM-2PM). A critical issue for cerebellar theory is the organization of granular layer activity in the cerebellum, which has been predicted by single-cell recordings and computational models. With SLM-2PM, calcium signals could be recorded from different network elements in acute cerebellar slices including granule cells (GrCs), Purkinje cells (PCs) and molecular layer interneurons. By combining WCRs with SLM-2PM, the spike/calcium relationship in GrCs and PCs could be extrapolated toward the detection of single spikes. The SLM-2PM technique made it possible to monitor activity of over tens to hundreds neurons simultaneously. GrC activity depended on the number of spikes in the input mossy fiber bursts. PC and molecular layer interneuron activity paralleled that in the underlying GrC population revealing the spread of activity through the cerebellar cortical network. Moreover, circuit activity was increased by the GABA-A receptor blocker, gabazine, and reduced by the AMPA and NMDA receptor blockers, NBQX and APV. The SLM-2PM analysis of spatiotemporal patterns lent experimental support to the time-window and center-surround organizing principles of the granular layer.
    04/2014; 8:92. DOI:10.3389/fncel.2014.00092
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    • "6 Atkin, S. D., Patel, S., Kocharyan, A., Holtzclaw, L. A., Weerth, S. H., Schram, V., et al. (2009)"
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    ABSTRACT: Gray matter protoplasmic astrocytes extend very thin processes and establish close contacts with synapses. It has been suggested that the release of neuroactive gliotransmitters at the tripartite synapse contributes to information processing. However, the concept of calcium (Ca(2+))-dependent gliotransmitter release from astrocytes, and the release mechanisms are being debated. Studying astrocytes in their natural environment is challenging because: (i) astrocytes are electrically silent; (ii) astrocytes and neurons express an overlapping repertoire of transmembrane receptors; (iii) the size of astrocyte processes in contact with synapses are below the resolution of confocal and two-photon microscopes (iv) bulk-loading techniques using fluorescent Ca(2+) indicators lack cellular specificity. In this review, we will discuss some limitations of conventional methodologies and highlight the interest of novel tools and approaches for studying gliotransmission. Genetically encoded Ca(2+) indicators (GECIs), light-gated channels, and exogenous receptors are being developed to selectively read out and stimulate astrocyte activity. Our review discusses emerging perspectives on: (i) the complexity of astrocyte Ca(2+) signaling revealed by GECIs; (ii) new pharmacogenetic and optogenetic approaches to activate specific Ca(2+) signaling pathways in astrocytes; (iii) classical and new techniques to monitor vesicle fusion in cultured astrocytes; (iv) possible strategies to express specifically reporter genes in astrocytes.
    Frontiers in Cellular Neuroscience 10/2013; 7:193. DOI:10.3389/fncel.2013.00193 · 4.29 Impact Factor
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