1
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Rupprecht P, Duss SN, Becker D, Lewis CM, Bohacek J, Helmchen F. Centripetal integration of past events in hippocampal astrocytes regulated by locus coeruleus. Nat Neurosci 2024; 27:927-939. [PMID: 38570661 PMCID: PMC11089000 DOI: 10.1038/s41593-024-01612-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 02/26/2024] [Indexed: 04/05/2024]
Abstract
An essential feature of neurons is their ability to centrally integrate information from their dendrites. The activity of astrocytes, in contrast, has been described as mostly uncoordinated across cellular compartments without clear central integration. Here we report conditional integration of calcium signals in astrocytic distal processes at their soma. In the hippocampus of adult mice of both sexes, we found that global astrocytic activity, as recorded with population calcium imaging, reflected past neuronal and behavioral events on a timescale of seconds. Salient past events, indicated by pupil dilations, facilitated the propagation of calcium signals from distal processes to the soma. Centripetal propagation to the soma was reproduced by optogenetic activation of the locus coeruleus, a key regulator of arousal, and reduced by pharmacological inhibition of α1-adrenergic receptors. Together, our results suggest that astrocytes are computational units of the brain that slowly and conditionally integrate calcium signals upon behaviorally relevant events.
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Affiliation(s)
- Peter Rupprecht
- Laboratory of Neural Circuit Dynamics, Brain Research Institute, University of Zurich, Zürich, Switzerland.
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland.
| | - Sian N Duss
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland
- Laboratory of Molecular and Behavioral Neuroscience, Institute for Neuroscience, Department of Health Sciences and Technology, ETH Zurich, Zürich, Switzerland
| | - Denise Becker
- Laboratory of Neural Circuit Dynamics, Brain Research Institute, University of Zurich, Zürich, Switzerland
| | - Christopher M Lewis
- Laboratory of Neural Circuit Dynamics, Brain Research Institute, University of Zurich, Zürich, Switzerland
| | - Johannes Bohacek
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland
- Laboratory of Molecular and Behavioral Neuroscience, Institute for Neuroscience, Department of Health Sciences and Technology, ETH Zurich, Zürich, Switzerland
| | - Fritjof Helmchen
- Laboratory of Neural Circuit Dynamics, Brain Research Institute, University of Zurich, Zürich, Switzerland.
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zürich, Switzerland.
- University Research Priority Program (URPP), Adaptive Brain Circuits in Development and Learning, University of Zurich, Zürich, Switzerland.
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2
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Role of Microglia and Astrocytes in Alzheimer’s Disease: From Neuroinflammation to Ca2+ Homeostasis Dysregulation. Cells 2022; 11:cells11172728. [PMID: 36078138 PMCID: PMC9454513 DOI: 10.3390/cells11172728] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common form of dementia worldwide, with a complex, poorly understood pathogenesis. Cerebral atrophy, amyloid-β (Aβ) plaques, and neurofibrillary tangles represent the main pathological hallmarks of the AD brain. Recently, neuroinflammation has been recognized as a prominent feature of the AD brain and substantial evidence suggests that the inflammatory response modulates disease progression. Additionally, dysregulation of calcium (Ca2+) homeostasis represents another early factor involved in the AD pathogenesis, as intracellular Ca2+ concentration is essential to ensure proper cellular and neuronal functions. Although growing evidence supports the involvement of Ca2+ in the mechanisms of neurodegeneration-related inflammatory processes, scant data are available on its contribution in microglia and astrocytes functioning, both in health and throughout the AD continuum. Nevertheless, AD-related aberrant Ca2+ signalling in astrocytes and microglia is crucially involved in the mechanisms underpinning neuroinflammatory processes that, in turn, impact neuronal Ca2+ homeostasis and brain function. In this light, we attempted to provide an overview of the current understanding of the interactions between the glia cells-mediated inflammatory responses and the molecular mechanisms involved in Ca2+ homeostasis dysregulation in AD.
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3
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Georgiou L, Echeverría A, Georgiou A, Kuhn B. Ca + activity maps of astrocytes tagged by axoastrocytic AAV transfer. SCIENCE ADVANCES 2022; 8:eabe5371. [PMID: 35138891 PMCID: PMC8827655 DOI: 10.1126/sciadv.abe5371] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/17/2021] [Indexed: 05/27/2023]
Abstract
Astrocytes exhibit localized Ca2+ microdomain (MD) activity thought to be actively involved in information processing in the brain. However, functional organization of Ca2+ MDs in space and time in relationship to behavior and neuronal activity is poorly understood. Here, we first show that adeno-associated virus (AAV) particles transfer anterogradely from axons to astrocytes. Then, we use this axoastrocytic AAV transfer to express genetically encoded Ca2+ indicators at high-contrast circuit specifically. In combination with two-photon microscopy and unbiased, event-based analysis, we investigated cortical astrocytes embedded in the vibrissal thalamocortical circuit. We found a wide range of Ca2+ MD signals, some of which were ultrafast (≤300 ms). Frequency and size of signals were extensively increased by locomotion but only subtly with sensory stimulation. The overlay of these signals resulted in behavior-dependent maps with characteristic Ca2+ activity hotspots, maybe representing memory engrams. These functional subdomains are stable over days, suggesting subcellular specialization.
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4
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Benfey N, Foubert D, Ruthazer ES. Glia Regulate the Development, Function, and Plasticity of the Visual System From Retina to Cortex. Front Neural Circuits 2022; 16:826664. [PMID: 35177968 PMCID: PMC8843846 DOI: 10.3389/fncir.2022.826664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/07/2022] [Indexed: 11/13/2022] Open
Abstract
Visual experience is mediated through a relay of finely-tuned neural circuits extending from the retina, to retinorecipient nuclei in the midbrain and thalamus, to the cortex which work together to translate light information entering our eyes into a complex and dynamic spatio-temporal representation of the world. While the experience-dependent developmental refinement and mature function of neurons in each major stage of the vertebrate visual system have been extensively characterized, the contributions of the glial cells populating each region are comparatively understudied despite important findings demonstrating that they mediate crucial processes related to the development, function, and plasticity of the system. In this article we review the mechanisms for neuron-glia communication throughout the vertebrate visual system, as well as functional roles attributed to astrocytes and microglia in visual system development and processing. We will also discuss important aspects of glial function that remain unclear, integrating the knowns and unknowns about glia in the visual system to advance new hypotheses to guide future experimental work.
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5
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Ahmadpour N, Kantroo M, Stobart JL. Extracellular Calcium Influx Pathways in Astrocyte Calcium Microdomain Physiology. Biomolecules 2021; 11:1467. [PMID: 34680100 PMCID: PMC8533159 DOI: 10.3390/biom11101467] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/25/2021] [Accepted: 10/01/2021] [Indexed: 02/08/2023] Open
Abstract
Astrocytes are complex glial cells that play many essential roles in the brain, including the fine-tuning of synaptic activity and blood flow. These roles are linked to fluctuations in intracellular Ca2+ within astrocytes. Recent advances in imaging techniques have identified localized Ca2+ transients within the fine processes of the astrocytic structure, which we term microdomain Ca2+ events. These Ca2+ transients are very diverse and occur under different conditions, including in the presence or absence of surrounding circuit activity. This complexity suggests that different signalling mechanisms mediate microdomain events which may then encode specific astrocyte functions from the modulation of synapses up to brain circuits and behaviour. Several recent studies have shown that a subset of astrocyte microdomain Ca2+ events occur rapidly following local neuronal circuit activity. In this review, we consider the physiological relevance of microdomain astrocyte Ca2+ signalling within brain circuits and outline possible pathways of extracellular Ca2+ influx through ionotropic receptors and other Ca2+ ion channels, which may contribute to astrocyte microdomain events with potentially fast dynamics.
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Affiliation(s)
| | | | - Jillian L. Stobart
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MG R3E 0T5, Canada; (N.A.); (M.K.)
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6
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McNeill J, Rudyk C, Hildebrand ME, Salmaso N. Ion Channels and Electrophysiological Properties of Astrocytes: Implications for Emergent Stimulation Technologies. Front Cell Neurosci 2021; 15:644126. [PMID: 34093129 PMCID: PMC8173131 DOI: 10.3389/fncel.2021.644126] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 04/26/2021] [Indexed: 12/12/2022] Open
Abstract
Astrocytes comprise a heterogeneous cell population characterized by distinct morphologies, protein expression and function. Unlike neurons, astrocytes do not generate action potentials, however, they are electrically dynamic cells with extensive electrophysiological heterogeneity and diversity. Astrocytes are hyperpolarized cells with low membrane resistance. They are heavily involved in the modulation of K+ and express an array of different voltage-dependent and voltage-independent channels to help with this ion regulation. In addition to these K+ channels, astrocytes also express several different types of Na+ channels; intracellular Na+ signaling in astrocytes has been linked to some of their functional properties. The physiological hallmark of astrocytes is their extensive intracellular Ca2+ signaling cascades, which vary at the regional, subregional, and cellular levels. In this review article, we highlight the physiological properties of astrocytes and the implications for their function and influence of network and synaptic activity. Furthermore, we discuss the implications of these differences in the context of optogenetic and DREADD experiments and consider whether these tools represent physiologically relevant techniques for the interrogation of astrocyte function.
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Affiliation(s)
- Jessica McNeill
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | | | | | - Natalina Salmaso
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
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7
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Ryczko D, Hanini‐Daoud M, Condamine S, Bréant BJB, Fougère M, Araya R, Kolta A. S100β‐mediated astroglial control of firing and input processing in layer 5 pyramidal neurons of the mouse visual cortex. J Physiol 2020; 599:677-707. [DOI: 10.1113/jp280501] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Affiliation(s)
- Dimitri Ryczko
- Département de Neurosciences Université de Montréal Montréal QC Canada
- Département de Pharmacologie‐Physiologie Université de Sherbrooke Sherbrooke QC Canada
- Centre de recherche du CHUS Sherbrooke QC Canada
- Institut de Pharmacologie de Sherbrooke Sherbrooke QC Canada
- Centre d'excellence en neurosciences de l'Université de Sherbrooke Sherbrooke QC Canada
| | | | - Steven Condamine
- Département de Neurosciences Université de Montréal Montréal QC Canada
| | | | - Maxime Fougère
- Département de Pharmacologie‐Physiologie Université de Sherbrooke Sherbrooke QC Canada
| | - Roberto Araya
- Département de Neurosciences Université de Montréal Montréal QC Canada
| | - Arlette Kolta
- Département de Neurosciences Université de Montréal Montréal QC Canada
- Faculté de Médecine Dentaire Université de Montréal Montréal QC Canada
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8
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Semyanov A, Henneberger C, Agarwal A. Making sense of astrocytic calcium signals — from acquisition to interpretation. Nat Rev Neurosci 2020; 21:551-564. [DOI: 10.1038/s41583-020-0361-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2020] [Indexed: 12/31/2022]
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9
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Hernandez E, MacNamee SE, Kaplan LR, Lance K, Garcia-Verdugo HD, Farhadi DS, Deer C, Lee SW, Oland LA. The astrocyte network in the ventral nerve cord neuropil of the Drosophila third-instar larva. J Comp Neurol 2020; 528:1683-1703. [PMID: 31909826 DOI: 10.1002/cne.24852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 12/19/2019] [Accepted: 12/20/2019] [Indexed: 11/10/2022]
Abstract
Understanding neuronal function at the local and circuit level requires understanding astrocyte function. We have provided a detailed analysis of astrocyte morphology and territory in the Drosophila third-instar ventral nerve cord where there already exists considerable understanding of the neuronal network. Astrocyte shape varies more than previously reported; many have bilaterally symmetrical partners, many have a high percentage of their arborization in adjacent segments, and many have branches that follow structural features. Taken together, our data are consistent with, but not fully explained by, a model of a developmental growth process dominated by competitive or repulsive interactions between astrocytes. Our data suggest that the model should also include cell-autonomous aspects, as well as the use of structural features for growth. Variation in location of arborization territory for identified astrocytes was great enough that a standardized scheme of neuropil division among the six astrocytes that populate each hemi-segment is not possible at the third instar. The arborizations of the astrocytes can extend across neuronal functional domains. The ventral astrocyte in particular, whose territory can extend well into the proprioceptive region of the neuropil, has no obvious branching pattern that correlates with domains of particular sensory modalities, suggesting that the astrocyte would respond to neuronal activity in any of the sensory modalities, perhaps integrating across them. This study sets the stage for future studies that will generate a robust, functionally oriented connectome that includes both partners in neuronal circuits-the neurons and the glial cells, providing the foundation necessary for studies to elucidate neuron-glia interactions in this neuropil.
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Key Words
- RRID:Abcam Cat# ab6953, RRID:AB_955010
- RRID:BDSC Cat# 30125, RRID:BDSC_30125
- RRID:BDSC Cat# 38760, RRID:BDSC_38760
- RRID:BDSC Cat# 4775, RRID:BDSC_4775
- RRID:BDSC Cat# 5692, RRID:BDSC_5692
- RRID:BDSC Cat# 64085, RRID:BDSC_64085
- RRID:BDSC Cat# 6938, RRID:BDSC_6938
- RRID:Bio-rad Cat # MCA1360, RRID:AB_322378
- RRID:Cell Signaling Technology Cat # 3724, RRID:AB_1549585
- RRID:DSHB Cat# 1D4, RRID:AB_528235
- RRID:DSHB Cat# nc82, RRID:AB_2314866
- RRID:Jackson ImmunoResearch Labs Cat# 115-167-003, RRID:AB_2338709
- RRID:Molecular Probes Cat# 6455, RRID:AB_2314543
- RRID:Molecular Probes Cat# A-21236, RRID:AB_141725
- RRID:Novus Cat # NBP1-06712, RRID:AB_1625981
- RRID:Thermo Fisher Scientific Cat# A-11034, RRID:AB_2576217.
- glial cells
- neuron-glia interaction
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Affiliation(s)
- Ernesto Hernandez
- Department of Neuroscience, University of Arizona, Tucson, Arizona.,University of Illinois at Chicago School of Medicine, Rockford, Illinois
| | - Sarah E MacNamee
- Department of Neuroscience, University of Arizona, Tucson, Arizona.,Inscopix, Palo Alto, California
| | - Leah R Kaplan
- Department of Neuroscience, University of Arizona, Tucson, Arizona.,Consortium for Science, Policy & Outcomes, Arizona State University, Washington, DC, Washington
| | - Kim Lance
- Department of Neuroscience, University of Arizona, Tucson, Arizona
| | | | - Dara S Farhadi
- Department of Neuroscience, University of Arizona, Tucson, Arizona.,College of Medicine-Phoenix, University of Arizona, Phoenix, Arizona
| | - Christine Deer
- Department of Neuroscience, University of Arizona, Tucson, Arizona.,Research Technologies Group, Data Visualization Team, University of Arizona, University Information Technology Service, Tucson, Arizona
| | - Si W Lee
- Department of Neuroscience, University of Arizona, Tucson, Arizona
| | - Lynne A Oland
- Department of Neuroscience, University of Arizona, Tucson, Arizona
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10
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Slezak M, Kandler S, Van Veldhoven PP, Van den Haute C, Bonin V, Holt MG. Distinct Mechanisms for Visual and Motor-Related Astrocyte Responses in Mouse Visual Cortex. Curr Biol 2019; 29:3120-3127.e5. [PMID: 31495587 PMCID: PMC6859477 DOI: 10.1016/j.cub.2019.07.078] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 06/19/2019] [Accepted: 07/26/2019] [Indexed: 02/02/2023]
Abstract
Astrocytes are a major cell type in the mammalian nervous system, are in close proximity to neurons, and show rich Ca2+ activity thought to mediate cellular outputs. Astrocytes show activity linked to sensory [1, 2] and motor [3, 4] events, reflecting local neural activity and brain-wide neuromodulatory inputs. Sensory responses are highly variable [5, 6, 7, 8, 9, 10], which may reflect interactions between distinct input types [6, 7, 9]. However, the diversity of inputs generating astrocyte activity, particularly during sensory stimulation and behavior, is not fully understood [11, 12]. Using a combination of Ca2+ imaging, a treadmill assay, and visual stimulation, we examined the properties of astrocyte activity in mouse visual cortex associated with motor or sensory events. Consistent with previous work, motor activity activated astrocytes across the cortex with little specificity, reflecting a diffuse neuromodulatory mechanism. In contrast, moving visual stimuli generated specific activity patterns that reflected the stimulus' trajectory within the visual field, precisely as one would predict if astrocytes reported local neural activity. Visual responses depended strongly on behavioral state, with astrocytes showing high amplitude Ca2+ transients during locomotion and little activity during stillness. Furthermore, the amplitudes of visual responses were highly correlated with pupil size, suggesting a role of arousal. Interestingly, while depletion of cortical noradrenaline abolished locomotor responses, visual responses were only reduced in amplitude and their spatiotemporal organization remained intact, suggesting two distinct types of inputs underlie visual responses. We conclude that cortical astrocytes integrate local sensory information and behavioral state, suggesting a role in information processing. Astrocytes of moving mice display robust retinotopic responses to visual stimuli Sensory responses are distinguishable from responses to locomotion Vision-driven responses are correlated to arousal Vision- and arousal-driven responses are differentially regulated by noradrenaline
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Affiliation(s)
- Michal Slezak
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; VIB Center for Brain and Disease Research, Herestraat 49-Box 602, 3000 Leuven, Belgium
| | - Steffen Kandler
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium
| | - Paul P Van Veldhoven
- KU Leuven, Department of Cellular and Molecular Medicine, LIPIT, Herestraat 49-Box 601, 3000 Leuven, Belgium
| | - Chris Van den Haute
- KU Leuven, Laboratory for Neurobiology and Gene Therapy and Leuven Brain Institute, RK-Herestraat 49-Box 1023, 3000 Leuven, Belgium; KU Leuven, Leuven Viral Vector Core, RK-Herestraat 49, 3000 Leuven, Belgium
| | - Vincent Bonin
- Neuro-Electronics Research Flanders (NERF), Kapeldreef 75, 3001 Leuven, Belgium; IMEC, Kapeldreef 75, 3001 Leuven, Belgium; KU Leuven, Department of Biology and Leuven Brain Institute, Naamsestraat 59-Box 2465, 3001 Leuven, Belgium.
| | - Matthew G Holt
- VIB Center for Brain and Disease Research, Herestraat 49-Box 602, 3000 Leuven, Belgium; KU Leuven, Department of Neuroscience and Leuven Brain Institute, Herestraat 49-Box 1021, 3000 Leuven, Belgium.
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11
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Denizot A, Arizono M, Nägerl UV, Soula H, Berry H. Simulation of calcium signaling in fine astrocytic processes: Effect of spatial properties on spontaneous activity. PLoS Comput Biol 2019; 15:e1006795. [PMID: 31425510 PMCID: PMC6726244 DOI: 10.1371/journal.pcbi.1006795] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 09/04/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
Astrocytes, a glial cell type of the central nervous system, have emerged as detectors and regulators of neuronal information processing. Astrocyte excitability resides in transient variations of free cytosolic calcium concentration over a range of temporal and spatial scales, from sub-microdomains to waves propagating throughout the cell. Despite extensive experimental approaches, it is not clear how these signals are transmitted to and integrated within an astrocyte. The localization of the main molecular actors and the geometry of the system, including the spatial organization of calcium channels IP3R, are deemed essential. However, as most calcium signals occur in astrocytic ramifications that are too fine to be resolved by conventional light microscopy, most of those spatial data are unknown and computational modeling remains the only methodology to study this issue. Here, we propose an IP3R-mediated calcium signaling model for dynamics in such small sub-cellular volumes. To account for the expected stochasticity and low copy numbers, our model is both spatially explicit and particle-based. Extensive simulations show that spontaneous calcium signals arise in the model via the interplay between excitability and stochasticity. The model reproduces the main forms of calcium signals and indicates that their frequency crucially depends on the spatial organization of the IP3R channels. Importantly, we show that two processes expressing exactly the same calcium channels can display different types of calcium signals depending on the spatial organization of the channels. Our model with realistic process volume and calcium concentrations successfully reproduces spontaneous calcium signals that we measured in calcium micro-domains with confocal microscopy and predicts that local variations of calcium indicators might contribute to the diversity of calcium signals observed in astrocytes. To our knowledge, this model is the first model suited to investigate calcium dynamics in fine astrocytic processes and to propose plausible mechanisms responsible for their variability.
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Affiliation(s)
- Audrey Denizot
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
| | - Misa Arizono
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - U. Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Hédi Soula
- INRIA, F-69603, Villeurbanne, France
- Univ P&M Curie, CRC, INSERM UMRS 1138, F-75006, Paris, France
| | - Hugues Berry
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
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12
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Semyanov A. Spatiotemporal pattern of calcium activity in astrocytic network. Cell Calcium 2019; 78:15-25. [DOI: 10.1016/j.ceca.2018.12.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/16/2018] [Accepted: 12/16/2018] [Indexed: 12/22/2022]
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13
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Wu YW, Gordleeva S, Tang X, Shih PY, Dembitskaya Y, Semyanov A. Morphological profile determines the frequency of spontaneous calcium events in astrocytic processes. Glia 2018; 67:246-262. [DOI: 10.1002/glia.23537] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/19/2018] [Accepted: 09/03/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Yu-Wei Wu
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Molecular Biology, Academia Sinica; Nankang Taipei Taiwan
| | - Susan Gordleeva
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
| | - Xiaofang Tang
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
| | - Pei-Yu Shih
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
| | - Yulia Dembitskaya
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
| | - Alexey Semyanov
- Brain Science Institute (BSI), RIKEN; Wako-shi Saitama Japan
- Institute of Neuroscience, University of Nizhny Novgorod; Nizhny Novgorod Russia
- Department of Molecular Neurobiology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences; Moscow Russia
- All-Russian Research Institute of Medicinal and Aromatic Plants; Moscow Russia
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14
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Stobart JL, Ferrari KD, Barrett MJP, Stobart MJ, Looser ZJ, Saab AS, Weber B. Long-term In Vivo Calcium Imaging of Astrocytes Reveals Distinct Cellular Compartment Responses to Sensory Stimulation. Cereb Cortex 2018; 28:184-198. [PMID: 28968832 DOI: 10.1093/cercor/bhw366] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/02/2016] [Indexed: 01/28/2023] Open
Abstract
Localized, heterogeneous calcium transients occur throughout astrocytes, but the characteristics and long-term stability of these signals, particularly in response to sensory stimulation, remain unknown. Here, we used a genetically encoded calcium indicator and an activity-based image analysis scheme to monitor astrocyte calcium activity in vivo. We found that different subcellular compartments (processes, somata, and endfeet) displayed distinct signaling characteristics. Closer examination of individual signals showed that sensory stimulation elevated the number of specific types of calcium peaks within astrocyte processes and somata, in a cortical layer-dependent manner, and that the signals became more synchronous upon sensory stimulation. Although mice genetically lacking astrocytic IP3R-dependent calcium signaling (Ip3r2-/-) had fewer signal peaks, the response to sensory stimulation was sustained, suggesting other calcium pathways are also involved. Long-term imaging of astrocyte populations revealed that all compartments reliably responded to stimulation over several months, but that the location of the response within processes may vary. These previously unknown characteristics of subcellular astrocyte calcium signals provide new insights into how astrocytes may encode local neuronal circuit activity.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Michael J Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
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15
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Lind BL, Jessen SB, Lønstrup M, Joséphine C, Bonvento G, Lauritzen M. Fast Ca 2+ responses in astrocyte end-feet and neurovascular coupling in mice. Glia 2017; 66:348-358. [PMID: 29058353 DOI: 10.1002/glia.23246] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 01/09/2023]
Abstract
Cerebral blood flow (CBF) is regulated by the activity of neurons and astrocytes. Understanding how these cells control activity-dependent increases in CBF is crucial to interpreting functional neuroimaging signals. The relative importance of neurons and astrocytes is debated, as are the functional implications of fast Ca2+ changes in astrocytes versus neurons. Here, we used two-photon microscopy to assess Ca2+ changes in neuropil, astrocyte processes, and astrocyte end-feet in response to whisker pad stimulation in mice. We also developed a pixel-based analysis to improve the detection of rapid Ca2+ signals in the subcellular compartments of astrocytes. Fast Ca2+ responses were observed using both chemical and genetically encoded Ca2+ indicators in astrocyte end-feet prior to dilation of arterioles and capillaries. A low dose of the NMDA receptor antagonist (5R,10s)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine-hydrogen-maleate (MK801) attenuated fast Ca2+ responses in the neuropil and astrocyte processes, but not in astrocyte end-feet, and the evoked CBF response was preserved. In addition, a low dose of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), an agonist for the extrasynaptic GABAA receptor (GABAA R), increased CBF responses and the fast Ca2+ response in astrocyte end-feet but did not affect Ca2+ responses in astrocyte processes and neuropil. These results suggest that fast Ca2+ increases in the neuropil and astrocyte processes are not necessary for an evoked CBF response. In contrast, as local fast Ca2+ responses in astrocyte end-feet are unaffected by MK801 but increase via GABAA R-dependent mechanisms that also increased CBF responses, we hypothesize that the fast Ca2+ increases in end-feet adjust CBF during synaptic activity.
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Affiliation(s)
- Barbara Lykke Lind
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Sanne Barsballe Jessen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Micael Lønstrup
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark
| | - Charlène Joséphine
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de Biologie François-Jacob, Molecular Imaging Research Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Gilles Bonvento
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de Biologie François-Jacob, Molecular Imaging Research Center (MIRCen), CNRS UMR 9199, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Martin Lauritzen
- Department of Neuroscience and Center for Healthy Aging, University of Copenhagen, Denmark.,Department of Clinical Neurophysiology, Glostrup Hospital, Denmark
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Transient Oxygen/Glucose Deprivation Causes a Delayed Loss of Mitochondria and Increases Spontaneous Calcium Signaling in Astrocytic Processes. J Neurosci 2017; 36:7109-27. [PMID: 27383588 DOI: 10.1523/jneurosci.4518-15.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 05/24/2016] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED Recently, mitochondria have been localized to astrocytic processes where they shape Ca(2+) signaling; this relationship has not been examined in models of ischemia/reperfusion. We biolistically transfected astrocytes in rat hippocampal slice cultures to facilitate fluorescent confocal microscopy, and subjected these slices to transient oxygen/glucose deprivation (OGD) that causes delayed excitotoxic death of CA1 pyramidal neurons. This insult caused a delayed loss of mitochondria from astrocytic processes and increased colocalization of mitochondria with the autophagosome marker LC3B. The losses of neurons in area CA1 and mitochondria in astrocytic processes were blocked by ionotropic glutamate receptor (iGluR) antagonists, tetrodotoxin, ziconotide (Ca(2+) channel blocker), two inhibitors of reversed Na(+)/Ca(2+) exchange (KB-R7943, YM-244769), or two inhibitors of calcineurin (cyclosporin-A, FK506). The effects of OGD were mimicked by NMDA. The glutamate uptake inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-l-aspartate increased neuronal loss after OGD or NMDA, and blocked the loss of astrocytic mitochondria. Exogenous glutamate in the presence of iGluR antagonists caused a loss of mitochondria without a decrease in neurons in area CA1. Using the genetic Ca(2+) indicator Lck-GCaMP-6S, we observed two types of Ca(2+) signals: (1) in the cytoplasm surrounding mitochondria (mitochondrially centered) and (2) traversing the space between mitochondria (extramitochondrial). The spatial spread, kinetics, and frequency of these events were different. The amplitude of both types was doubled and the spread of both types changed by ∼2-fold 24 h after OGD. Together, these data suggest that pathologic activation of glutamate transport and increased astrocytic Ca(2+) through reversed Na(+)/Ca(2+) exchange triggers mitochondrial loss and dramatic increases in Ca(2+) signaling in astrocytic processes. SIGNIFICANCE STATEMENT Astrocytes, the most abundant cell type in the brain, are vital integrators of signaling and metabolism. Each astrocyte consists of many long, thin branches, called processes, which ensheathe vasculature and thousands of synapses. Mitochondria occupy the majority of each process. This occupancy is decreased by ∼50% 24 h after an in vitro model of ischemia/reperfusion injury, due to delayed fragmentation and mitophagy. The mechanism appears to be independent of neuropathology, instead involving an extended period of high glutamate uptake into astrocytes. Our data suggest that mitochondria serve as spatial buffers, and possibly even as a source of calcium signals in astrocytic processes. Loss of mitochondria resulted in drastically altered calcium signaling that could disrupt neurovascular coupling and gliotransmission.
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Abstract
Rapid advances in Ca2+ imaging techniques enable us to simultaneously monitor the activities of hundreds of astrocytes in the intact brain, thus providing a powerful tool for understanding the functions of both host and engrafted astrocytes in sensory processing in vivo. These techniques include both improved Ca2+ indicators and advanced optical recording methods. Astrocytes in multiple cortical and sub-cortical areas are able to respond to the corresponding sensory modalities. These sensory stimuli produce astrocytic Ca2+ responses through different cellular mechanisms. In addition, it has been suggested that astrocytic gene deficiencies in various sensory systems cause impairments in sensory circuits and cognition. Therefore, glial transplantation would be a potentially interesting approach for the cell-based therapy for glia-related disorders. There are multiple cell sources for glial transplantation, including neural stem cells, glial progenitors, and pluripotent stem cells. Both in vitro and in vivo studies have shown that engrafted astrocytes derived from these cell sources are capable of responding to sensory stimulation by elevating the intracellular Ca2+ concentration. These results indicate that engrafted astrocytes not only morphologically but also functionally integrate into the host neural network. Until now, many animal studies have proven that glial transplantation would be a good choice for treating multiple glial disorders. Together, these studies on the sensory responses of host and engrafted astrocytes have provided us a novel perspective in both neuron-glia circuit functions and future treatment strategies for glial disorders.
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Affiliation(s)
- Kuan Zhang
- Brain Research Center and State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China
| | - Xiaowei Chen
- Brain Research Center and State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
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18
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López-Hidalgo M, Kellner V, Schummers J. Astrocyte Calcium Responses to Sensory Input: Influence of Circuit Organization and Experimental Factors. Front Neural Circuits 2017; 11:16. [PMID: 28381991 PMCID: PMC5360724 DOI: 10.3389/fncir.2017.00016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 02/24/2017] [Indexed: 01/08/2023] Open
Affiliation(s)
| | - Vered Kellner
- Max Planck Florida Institute for Neuroscience Jupiter, FL, USA
| | - James Schummers
- Max Planck Florida Institute for Neuroscience Jupiter, FL, USA
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Nakayama R, Sasaki T, Tanaka KF, Ikegaya Y. Subcellular calcium dynamics during juvenile development in mouse hippocampal astrocytes. Eur J Neurosci 2016; 43:923-32. [PMID: 27041234 DOI: 10.1111/ejn.13188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 12/26/2015] [Accepted: 01/26/2016] [Indexed: 12/15/2022]
Abstract
Astrocytes generate calcium signals throughout their fine processes, which are assumed to locally regulate neighbouring neurotransmission and blood flow. The intercellular morphological relationships mature during juvenile periods when astrocytes elongate highly ramified processes. In this study, we examined developmental changes in calcium activity patterns of single hippocampal astrocytes using a transgenic mouse line in which astrocytes selectively express a genetically encoded calcium indicator, Yellow Cameleon-Nano50. Compared with postnatal day 7, astrocytes at postnatal day 30 showed larger subcellular calcium events and a greater proportion of somatic events. At both ages, the calcium activity was abolished by removal of extracellular calcium ions. Calcium events in late juvenile astrocytes were not affected by spontaneously occurring sharp waves that trigger synchronized neuronal spikes, implying the independence of astrocyte calcium signals from neuronal synchronization. These results demonstrate that astrocytes undergo dynamic changes in their activity patterns during juvenile development.
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Affiliation(s)
- Ryota Nakayama
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Takuya Sasaki
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.,Center for Information and Neural Networks, Osaka, Japan
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