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Savtchouk I, Carriero G, Volterra A. Studying Axon-Astrocyte Functional Interactions by 3D Two-Photon Ca 2+ Imaging: A Practical Guide to Experiments and "Big Data" Analysis. Front Cell Neurosci 2018; 12:98. [PMID: 29706870 PMCID: PMC5908897 DOI: 10.3389/fncel.2018.00098] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/22/2018] [Indexed: 01/06/2023] Open
Abstract
Recent advances in fast volumetric imaging have enabled rapid generation of large amounts of multi-dimensional functional data. While many computer frameworks exist for data storage and analysis of the multi-gigabyte Ca2+ imaging experiments in neurons, they are less useful for analyzing Ca2+ dynamics in astrocytes, where transients do not follow a predictable spatio-temporal distribution pattern. In this manuscript, we provide a detailed protocol and commentary for recording and analyzing three-dimensional (3D) Ca2+ transients through time in GCaMP6f-expressing astrocytes of adult brain slices in response to axonal stimulation, using our recently developed tools to perform interactive exploration, filtering, and time-correlation analysis of the transients. In addition to the protocol, we release our in-house software tools and discuss parameters pertinent to conducting axonal stimulation/response experiments across various brain regions and conditions. Our software tools are available from the Volterra Lab webpage at https://wwwfbm.unil.ch/dnf/group/glia-an-active-synaptic-partner/member/volterra-andrea-volterra in the form of software plugins for Image J (NIH)—a de facto standard in scientific image analysis. Three programs are available: MultiROI_TZ_profiler for interactive graphing of several movable ROIs simultaneously, Gaussian_Filter5D for Gaussian filtering in several dimensions, and Correlation_Calculator for computing various cross-correlation parameters on voxel collections through time.
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Affiliation(s)
- Iaroslav Savtchouk
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Giovanni Carriero
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Andrea Volterra
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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202
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Botulinum Toxin Type A-A Modulator of Spinal Neuron-Glia Interactions under Neuropathic Pain Conditions. Toxins (Basel) 2018; 10:toxins10040145. [PMID: 29614835 PMCID: PMC5923311 DOI: 10.3390/toxins10040145] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 03/27/2018] [Accepted: 03/30/2018] [Indexed: 12/29/2022] Open
Abstract
Neuropathic pain represents a significant clinical problem because it is a chronic condition often refractory to available therapy. Therefore, there is still a strong need for new analgesics. Botulinum neurotoxin A (BoNT/A) is used to treat a variety of clinical diseases associated with pain. Glia are in continuous bi-directional communication with neurons to direct the formation and refinement of synaptic connectivity. This review addresses the effects of BoNT/A on the relationship between glia and neurons under neuropathic pain. The inhibitory action of BoNT/A on synaptic vesicle fusion that blocks the release of miscellaneous pain-related neurotransmitters is known. However, increasing evidence suggests that the analgesic effect of BoNT/A is mediated through neurons and glial cells, especially microglia. In vitro studies provide evidence that BoNT/A exerts its anti-inflammatory effect by diminishing NF-κB, p38 and ERK1/2 phosphorylation in microglia and directly interacts with Toll-like receptor 2 (TLR2). Furthermore, BoNT/A appears to have no more than a slight effect on astroglia. The full activation of TLR2 in astroglia appears to require the presence of functional TLR4 in microglia, emphasizing the significant interaction between those cell types. In this review, we discuss whether and how BoNT/A affects the spinal neuron–glia interaction and reduces the development of neuropathy.
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203
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Wotton CA, Quon EF, Palmer AC, Bekar LK. Corticosterone and serotonin similarly influence GABAergic and purinergic pathways to affect cortical inhibitory networks. J Neuroendocrinol 2018. [PMID: 29543349 DOI: 10.1111/jne.12592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Both serotonin (5-HT) and stress exert changes in cortical inhibitory tone to shape the activity of cortical networks. Because astrocytes are also known to affect inhibition through established purinergic pathways, we assessed the role of GABA and purinergic pathways with respect to the effects of rapid corticosterone (CORT) and 5-HT on cortical inhibition. We used a paired-pulse paradigm (P1 and P2) in acutely isolated mouse brain slices to evaluate changes in cortical evoked inhibition. Normally, 5-HT decreases the amplitude of the first pulse P1, whereas it increases the amplitude of P2 (increasing frequency transmission). Interestingly, it was observed that CORT application decreased P1 and increased P2 similar to that of 5-HT application. Given that CORT and 5-HT are known to modulate inhibition, we applied the GABAA antagonist bicuculline in the presence of both and found that the increase in P2 and the P2/P1 was lost, providing evidence for a common mechanism involving GABAA receptor signalling. Additional occlusion experiments (ie, 5-HT in presence of CORT and CORT in presence of 5-HT) provide further support for a common mechanism. Because both 5-HT and CORT blocked the increase in P2 and P2/P1 with respect to the other, we suggest 5-HT/CORT already utilise the shared mechanism to affect cortical inhibition. Using low concentrations of the GAPDH inhibitor iodoacetate, as commonly used to selectively disrupt astrocyte metabolism, we found that the increase in P2 and P2/P1 was similarly blocked in response to both CORT and 5-HT. Because astrocyte signalling depends in large part on purinergic pathways, the purinergic contribution was assessed using Ab129 (P2Y antagonist) and SCH 58261 (A2A antagonist). Once again, P2Y and A2A receptor blockade similarly disrupted 5-HT- or CORT-mediated increases in P2 and P2/P1. Taken together, these results support the common involvement of GABAergic and purinergic pathways in the effects of CORT and 5-HT that may also involve astrocytes.
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Affiliation(s)
- C A Wotton
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - E F Quon
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - A C Palmer
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - L K Bekar
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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204
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Dong Q, Liu Q, Li R, Wang A, Bu Q, Wang KH, Chang Q. Mechanism and consequence of abnormal calcium homeostasis in Rett syndrome astrocytes. eLife 2018; 7:33417. [PMID: 29595472 PMCID: PMC5902163 DOI: 10.7554/elife.33417] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 03/28/2018] [Indexed: 12/21/2022] Open
Abstract
Astrocytes play an important role in Rett syndrome (RTT) disease progression. Although the non-cell-autonomous effect of RTT astrocytes on neurons was documented, cell-autonomous phenotypes and mechanisms within RTT astrocytes are not well understood. We report that spontaneous calcium activity is abnormal in RTT astrocytes in vitro, in situ, and in vivo. Such abnormal calcium activity is mediated by calcium overload in the endoplasmic reticulum caused by abnormal store operated calcium entry, which is in part dependent on elevated expression of TRPC4. Furthermore, the abnormal calcium activity leads to excessive activation of extrasynaptic NMDA receptors (eNMDARs) on neighboring neurons and increased network excitability in Mecp2 knockout mice. Finally, both the abnormal astrocytic calcium activity and the excessive activation of eNMDARs are caused by Mecp2 deletion in astrocytes in vivo. Our findings provide evidence that abnormal calcium homeostasis is a key cell-autonomous phenotype in RTT astrocytes, and reveal its mechanism and consequence.
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Affiliation(s)
- Qiping Dong
- Waisman Center, University of Wisconsin-Madison, Madison, United States
| | - Qing Liu
- Unit on Neural Circuits and Adaptive Behaviors, National Institute of Mental Health, Bethesda, United States
| | - Ronghui Li
- Waisman Center, University of Wisconsin-Madison, Madison, United States
| | - Anxin Wang
- Waisman Center, University of Wisconsin-Madison, Madison, United States
| | - Qian Bu
- Waisman Center, University of Wisconsin-Madison, Madison, United States
| | - Kuan Hong Wang
- Unit on Neural Circuits and Adaptive Behaviors, National Institute of Mental Health, Bethesda, United States
| | - Qiang Chang
- Waisman Center, University of Wisconsin-Madison, Madison, United States.,Department of Medical Genetics, University of Wisconsin-Madison, Madison, United States.,Department of Neurology, University of Wisconsin-Madison, Madison, United States
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205
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Covelo A, Araque A. Neuronal activity determines distinct gliotransmitter release from a single astrocyte. eLife 2018; 7:32237. [PMID: 29380725 PMCID: PMC5790377 DOI: 10.7554/elife.32237] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/23/2018] [Indexed: 12/11/2022] Open
Abstract
Accumulating evidence indicates that astrocytes are actively involved in brain function by regulating synaptic activity and plasticity. Different gliotransmitters, such as glutamate, ATP, GABA or D-serine, released form astrocytes have been shown to induce different forms of synaptic regulation. However, whether a single astrocyte may release different gliotransmitters is unknown. Here we show that mouse hippocampal astrocytes activated by endogenous (neuron-released endocannabinoids or GABA) or exogenous (single astrocyte Ca2+ uncaging) stimuli modulate putative single CA3-CA1 hippocampal synapses. The astrocyte-mediated synaptic modulation was biphasic and consisted of an initial glutamate-mediated potentiation followed by a purinergic-mediated depression of neurotransmitter release. The temporal dynamic properties of this biphasic synaptic regulation depended on the firing frequency and duration of the neuronal activity that stimulated astrocytes. Present results indicate that single astrocytes can decode neuronal activity and, in response, release distinct gliotransmitters to differentially regulate neurotransmission at putative single synapses.
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Affiliation(s)
- Ana Covelo
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
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206
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Guerra-Gomes S, Sousa N, Pinto L, Oliveira JF. Functional Roles of Astrocyte Calcium Elevations: From Synapses to Behavior. Front Cell Neurosci 2018; 11:427. [PMID: 29386997 PMCID: PMC5776095 DOI: 10.3389/fncel.2017.00427] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/20/2017] [Indexed: 12/22/2022] Open
Abstract
Astrocytes are fundamental players in the regulation of synaptic transmission and plasticity. They display unique morphological and phenotypical features that allow to monitor and to dynamically respond to changes. One of the hallmarks of the astrocytic response is the generation of calcium elevations, which further affect downstream cellular processes. Technical advances in the field have allowed to spatially and to temporally quantify and qualify these elevations. However, the impact on brain function remains poorly understood. In this review, we discuss evidences of the functional impact of heterogeneous astrocytic calcium events in several brain regions, and their consequences in synapses, circuits, and behavior.
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Affiliation(s)
- Sónia Guerra-Gomes
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s – PT Government Associate Laboratory, Braga, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s – PT Government Associate Laboratory, Braga, Portugal
| | - Luísa Pinto
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s – PT Government Associate Laboratory, Braga, Portugal
| | - João F. Oliveira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal
- ICVS/3B’s – PT Government Associate Laboratory, Braga, Portugal
- DIGARC, Polytechnic Institute of Cávado and Ave, Barcelos, Portugal
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207
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Lack of PINK1 alters glia innate immune responses and enhances inflammation-induced, nitric oxide-mediated neuron death. Sci Rep 2018; 8:383. [PMID: 29321620 PMCID: PMC5762685 DOI: 10.1038/s41598-017-18786-w] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 12/15/2017] [Indexed: 12/20/2022] Open
Abstract
Neuroinflammation is involved in the pathogenesis of Parkinson’s disease (PD) and other neurodegenerative disorders. We show that lack of PINK1- a mitochondrial kinase linked to recessive familial PD – leads to glia type-specific abnormalities of innate immunity. PINK1 loss enhances LPS/IFN-γ stimulated pro-inflammatory phenotypes of mixed astrocytes/microglia (increased iNOS, nitric oxide and COX-2, reduced IL-10) and pure astrocytes (increased iNOS, nitric oxide, TNF-α and IL-1β), while attenuating expression of both pro-inflammatory (TNF-α, IL-1β) and anti-inflammatory (IL-10) cytokines in microglia. These abnormalities are associated with increased inflammation-induced NF-κB signaling in astrocytes, and cause enhanced death of neurons co-cultured with inflamed PINK1−/− mixed glia and neuroblastoma cells exposed to conditioned medium from LPS/IFN-γ treated PINK1−/− mixed glia. Neuroblastoma cell death is prevented with an iNOS inhibitor, implicating increased nitric oxide production as the cause for enhanced death. Finally, we show for the first time that lack of a recessive PD gene (PINK1) increases α-Synuclein-induced nitric oxide production in all glia types (mixed glia, astrocytes and microglia). Our results describe a novel pathogenic mechanism in recessive PD, where PINK1 deficiency may increase neuron death via exacerbation of inflammatory stimuli-induced nitric oxide production and abnormal innate immune responses in glia cells.
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208
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Role of Purinergic Receptor P2Y1 in Spatiotemporal Ca 2+ Dynamics in Astrocytes. J Neurosci 2018; 38:1383-1395. [PMID: 29305530 DOI: 10.1523/jneurosci.2625-17.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/08/2023] Open
Abstract
Fine processes of astrocytes enwrap synapses and are well positioned to sense neuronal information via synaptic transmission. In rodents, astrocyte processes sense synaptic transmission via Gq-protein coupled receptors (GqPCR), including the P2Y1 receptor (P2Y1R), to generate Ca2+ signals. Astrocytes display numerous spontaneous microdomain Ca2+ signals; however, it is not clear whether such signals are due to local synaptic transmission and/or in what timeframe astrocytes sense local synaptic transmission. To ask whether GqPCRs mediate microdomain Ca2+ signals, we engineered mice (both sexes) to specifically overexpress P2Y1Rs in astrocytes, and we visualized Ca2+ signals via a genetically encoded Ca2+ indicator, GCaMP6f, in astrocytes from adult mice. Astrocytes overexpressing P2Y1Rs showed significantly larger Ca2+ signals in response to exogenously applied ligand and to repetitive electrical stimulation of axons compared with controls. However, we found no evidence of increased microdomain Ca2+ signals. Instead, Ca2+ waves appeared and propagated to occupy areas that were up to 80-fold larger than microdomain Ca2+ signals. These Ca2+ waves accounted for only 2% of total Ca2+ events, but they were 1.9-fold larger and 2.9-fold longer in duration than microdomain Ca2+ signals at processes. Ca2+ waves did not require action potentials for their generation and occurred in a probenecid-sensitive manner, indicating that the endogenous ligand for P2Y1R is elevated independently of synaptic transmission. Our data suggest that spontaneous microdomain Ca2+ signals occur independently of P2Y1R activation and that astrocytes may not encode neuronal information in response to synaptic transmission at a point source of neurotransmitter release.SIGNIFICANCE STATEMENT Astrocytes are thought to enwrap synapses with their processes to receive neuronal information via Gq-protein coupled receptors (GqPCRs). Astrocyte processes display numerous microdomain Ca2+ signals that occur spontaneously. To determine whether GqPCRs play a role in microdomain Ca2+ signals and the timeframe in which astrocytes sense neuronal information, we engineered mice whose astrocytes specifically overexpress the P2Y1 receptor, a major GqPCR in astrocytes. We found that overexpression of P2Y1 receptors in astrocytes did not increase microdomain Ca2+ signals in astrocyte processes but caused Ca2+ wavelike signals. Our data indicate that spontaneous microdomain Ca2+ signals do not require activation of P2Y1 receptors.
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209
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Kim SY, Hsu JE, Husbands LC, Kleim JA, Jones TA. Coordinated Plasticity of Synapses and Astrocytes Underlies Practice-Driven Functional Vicariation in Peri-Infarct Motor Cortex. J Neurosci 2018; 38:93-107. [PMID: 29133435 PMCID: PMC5761439 DOI: 10.1523/jneurosci.1295-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/05/2017] [Accepted: 11/03/2017] [Indexed: 01/05/2023] Open
Abstract
Motor rehabilitative training after stroke can improve motor function and promote topographical reorganization of remaining motor cortical movement representations, but this reorganization follows behavioral improvements. A more detailed understanding of the neural bases of rehabilitation efficacy is needed to inform therapeutic efforts to improve it. Using a rat model of upper extremity impairments after ischemic stroke, we examined effects of motor rehabilitative training at the ultrastructural level in peri-infarct motor cortex. Extensive training in a skilled reaching task promoted improved performance and recovery of more normal movements. This was linked with greater axodendritic synapse density and ultrastructural characteristics of enhanced synaptic efficacy that were coordinated with changes in perisynaptic astrocytic processes in the border region between head and forelimb areas of peri-infarct motor cortex. Disrupting synapses and motor maps by infusions of anisomycin (ANI) into anatomically reorganized motor, but not posterior parietal, cortex eliminated behavioral gains from rehabilitative training. In contrast, ANI infusion in the equivalent cortical region of intact animals had no effect on reaching skills. These results suggest that rehabilitative training efficacy for improving manual skills is mediated by synaptic plasticity in a region of motor cortex that, before lesions, is not essential for manual skills, but becomes so as a result of the training. These findings support that experience-driven synaptic structural reorganization underlies functional vicariation in residual motor cortex after motor cortical infarcts.SIGNIFICANCE STATEMENT Stroke is a leading cause of long-term disability. Motor rehabilitation, the main treatment for physical disability, is of variable efficacy. A better understanding of neural mechanisms underlying effective motor rehabilitation would inform strategies for improving it. Here, we reveal synaptic underpinnings of effective motor rehabilitation. Rehabilitative training improved manual skill in the paretic forelimb and induced the formation of special synapse subtypes in coordination with structural changes in astrocytes, a glial cell that influences neural communication. These changes were found in a region that is nonessential for manual skill in intact animals, but came to mediate this skill due to training after stroke. Therefore, motor rehabilitation efficacy depends on synaptic changes that enable remaining brain regions to assume new functions.
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Affiliation(s)
- Soo Young Kim
- Department of Integrative Biology, University of California, Berkeley, California 94720,
| | - J Edward Hsu
- Department of Neurosurgery, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
- Institute for Neuroscience
| | | | - Jeffrey A Kleim
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85287
| | - Theresa A Jones
- Institute for Neuroscience
- Psychology Department, University of Texas, Austin, Texas 78712, and
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210
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Sampedro-Piquero P, Begega A. Environmental Enrichment as a Positive Behavioral Intervention Across the Lifespan. Curr Neuropharmacol 2018; 15:459-470. [PMID: 27012955 PMCID: PMC5543669 DOI: 10.2174/1570159x14666160325115909] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/30/2015] [Accepted: 03/16/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND In recent decades, the interest in behavioral interventions has been growing due to the higher prevalence of age-related cognitive impairments. Hence, behavioral interventions, such as cognitive stimulation and physical activity, and along with these, our lifestyle (education level, work position, frequency of cognitive and social activities) have shown important benefits during the cognitive impairment, dementia and even recovery after brain injury. This is due to the fact that this type of intervention and activities promote the formation of a cognitive and brain reserve that allows tolerating brain damage during a long period of time without the appearance of cognitive symptoms. With regard to this, animal models have proved very useful in providing information about the brain mechanisms involved in the development of these cognitive and brain reserves and how they interact with each other. METHODS We summarize several studies showing the positive effects of Environmental Enrichment (EE), understood as a housing condition in which animals benefit from the sensory, physical, cognitive and social stimulation provided, on brain and cognitive functions usually impaired during aging. RESULTS Most of studies have shown that EE is a successful protocol to improve cognitive functions and reduce anxiety-related behaviors across the lifespan, as well as in animal models of neurodegenerative diseases. CONCLUSION Therefore, EE is a laboratory condition in which some aspects of an active lifestyle are reproduced.
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Affiliation(s)
- P Sampedro-Piquero
- Department of Biological and Health Psychology, Autonomous University of Madrid, Cantoblanco 28049, Madrid, Spain
| | - A Begega
- Neuroscience Laboratory, Psychology Department, University of Oviedo, Plaza Feijoo s/n 33003 Oviedo, INEUROPA, Spain
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211
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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212
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Astrocytes and presynaptic plasticity in the striatum: Evidence and unanswered questions. Brain Res Bull 2018; 136:17-25. [DOI: 10.1016/j.brainresbull.2017.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/30/2016] [Accepted: 01/02/2017] [Indexed: 02/03/2023]
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213
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 916] [Impact Index Per Article: 152.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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214
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Evidence for astrocyte purinergic signaling in cortical sensory adaptation and serotonin-mediated neuromodulation. Mol Cell Neurosci 2017; 88:53-61. [PMID: 29277734 DOI: 10.1016/j.mcn.2017.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 12/16/2017] [Accepted: 12/19/2017] [Indexed: 11/22/2022] Open
Abstract
In the somatosensory cortex, inhibitory networks are involved in low frequency sensory input adaptation/habituation that can be observed as a paired-pulse depression when using a dual stimulus electrophysiological paradigm. Given that astrocytes have been shown to regulate inhibitory interneuron activity, we hypothesized that astrocytes are involved in cortical sensory adaptation/habituation and constitute effectors of the 5HT-mediated increase in frequency transmission. Using extracellular recordings of evoked excitatory postsynaptic potentials (eEPSPs) in layer II/III of somatosensory cortex, we used various pharmacological approaches to assess the recruitment of astrocyte signaling in paired-pulse depression and serotonin-mediated increase in the paired-pulse ratio (pulse 2/pulse 1). In the absence of neuromodulators or pharmacological agents, the first eEPSP is much larger in amplitude than the second due to the recruitment of long-lasting evoked GABAA-dependent inhibitory activity from the first stimulus. Disruption of glycolysis or mGluR5 signaling resulted in a very similar loss of paired-pulse depression in field recordings. Interestingly, paired-pulse depression was similarly sensitive to disruption by ATP P2Y and adenosine A2A receptor antagonists. In addition, we show that pharmacological disruption of paired-pulse depression by mGluR5, P2Y, and glycolysis inhibition precluded serotonin effects on frequency transmission (typically increased the paired-pulse ratio). These data highlight the possibility for astrocyte involvement in cortical inhibitory activity seen in this simple cortical network and that serotonin may act on astrocytes to exert some aspects of its modulatory influence.
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215
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Vergouts M, Doyen PJ, Peeters M, Opsomer R, Hermans E. Constitutive downregulation protein kinase C epsilon in hSOD1 G93A astrocytes influences mGluR5 signaling and the regulation of glutamate uptake. Glia 2017; 66:749-761. [PMID: 29266405 DOI: 10.1002/glia.23279] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/19/2017] [Accepted: 11/24/2017] [Indexed: 01/06/2023]
Abstract
Accumulating evidence indicates that motor neuron degeneration in amyotrophic lateral sclerosis (ALS) is a non-cell-autonomous process and that impaired glutamate clearance by astrocytes, leading to excitotoxicity, could participate in progression of the disease. In astrocytes derived from an animal model of ALS (hSOD1G93A rats), activation of type 5 metabotropic glutamate receptor (mGluR5) fails to increase glutamate uptake, impeding a putative dynamic neuroprotective mechanism involving astrocytes. Using astrocyte cultures from hSOD1G93A rats, we have demonstrated that the typical Ca2+ oscillations associated with mGluR5 activation were reduced, and that the majority of cells responded with a sustained elevation of intracellular Ca2+ concentration. Since the expression of protein kinase C epsilon isoform (PKCɛ) has been found to be considerably reduced in astrocytes from hSOD1G93A rats, the consequences of manipulating its activity and expression on mGluR5 signaling and on the regulation of glutamate uptake have been examined. Increasing PKCɛ expression was found to restore Ca2+ oscillations induced by mGluR5 activation in hSOD1G93A -expressing astrocytes. This was also associated with an increase in glutamate uptake capacity in response to mGluR5 activation. Conversely, reducing PKCɛ expression in astrocytes from wild-type animals with specific PKCɛ-shRNAs was found to alter the mGluR5 associated oscillatory signaling profile, and consistently reduced the regulation of the glutamate uptake-mediated by mGluR5 activation. These results suggest that PKCɛ is required to generate Ca2+ oscillations following mGluR5 activation, which support the regulation of astrocytic glutamate uptake. Reduced expression of astrocytic PKCɛ could impair this neuroprotective process and participate in the progression of ALS.
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Affiliation(s)
- Maxime Vergouts
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
| | - Pierre J Doyen
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
| | - Michael Peeters
- De Duve Institute, Université catholique de Louvain, Avenue Hippocrate VIRO B1.74.07, Brussels, 1200, Belgium
| | - Remi Opsomer
- Alzheimer Dementia Group, Institute of Neuroscience, Université catholique de Louvain, Avenue Mounier B1.53.02, Brussels, 1200, Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
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216
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Heterogeneity and function of hippocampal macroglia. Cell Tissue Res 2017; 373:653-670. [PMID: 29204745 DOI: 10.1007/s00441-017-2746-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022]
Abstract
The contribution of glial cells to normal and impaired hippocampal function is increasingly being recognized, although important questions as to the mechanisms that these cells use for their crosstalk with neurons and capillaries are still unanswered or lead to controversy. Astrocytes in the hippocampus are morphologically variable and a single cell contacts with its processes more than 100,000 synapses. They predominantly express inward rectifier K+ channels and transporters serving homeostatic function but may also release gliotransmitters to modify neuronal signaling and brain circulation. Intracellular Ca2+ transients are key events in the interaction of astrocytes with neurons and the vasculature. Hippocampal NG2 glia represent a population of cells with proliferative capacity throughout adulthood. Intriguingly, they receive direct synaptic input from pyramidal neurons and interneurons and express a multitude of ion channels and receptors. Despite in-depth knowledge about the features of these transmembrane proteins, the physiological impact of NG2 glial cells and their synaptic input remain nebulous. Because of the low abundance of oligodendrocytes in the hippocampus, limited information is available about their specific properties. Given the multitude of signaling molecules expressed by the various types of hippocampal glial cells (and because of space constraints), we focus, in this review, on those properties that are considered key for the interaction of the respective cell type with its neighborhood.
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217
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Lines J, Covelo A, Gómez R, Liu L, Araque A. Synapse-Specific Regulation Revealed at Single Synapses Is Concealed When Recording Multiple Synapses. Front Cell Neurosci 2017; 11:367. [PMID: 29218000 PMCID: PMC5703853 DOI: 10.3389/fncel.2017.00367] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/07/2017] [Indexed: 12/23/2022] Open
Abstract
Synaptic transmission and its activity-dependent modulation, known as synaptic plasticity, are fundamental processes in nervous system function. Neurons may receive thousands of synaptic contacts, but synaptic regulation may occur only at individual or discrete subsets of synapses, which may have important consequences on the spatial extension of the modulation of synaptic information. Moreover, while several electrophysiological methods are used to assess synaptic transmission at different levels of observation, i.e., through local field potential and individual whole-cell recordings, their experimental limitations to detect synapse-specific modulation is poorly defined. We have investigated how well-known synapse-specific short-term plasticity, where some synapses are regulated and others left unregulated, mediated by astrocytes and endocannabinoid (eCB) signaling can be assessed at different observational levels. Using hippocampal slices, we have combined local field potential and whole-cell recordings of CA3-CA1 synaptic activity evoked by Schaffer collateral stimulation of either multiple or single synapses through bulk or minimal stimulation, respectively, to test the ability to detect short-term synaptic changes induced by eCB signaling. We also developed a mathematical model assuming a bimodal distribution of regulated and unregulated synapses based on realistic experimental data to simulate physiological results and to predict the experimental requirements of the different recording methods to detect discrete changes in subsets of synapses. We show that eCB-induced depolarization-induced suppression of excitation (DSE) and astrocyte-mediated synaptic potentiation can be observed when monitoring single or few synapses, but are statistically concealed when recording the activity of a large number of synapses. These results indicate that the electrophysiological methodology is critical to properly assess synaptic changes occurring in subsets of synapses, and they suggest that relevant synapse-specific regulatory phenomena may be experimentally undetected but may have important implications in the spatial extension of synaptic plasticity phenomena.
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Affiliation(s)
- Justin Lines
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Ana Covelo
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Ricardo Gómez
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Lan Liu
- Department of Statistics, University of Minnesota, Minneapolis, MN, United States
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
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218
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Taccola G, Sayenko D, Gad P, Gerasimenko Y, Edgerton VR. And yet it moves: Recovery of volitional control after spinal cord injury. Prog Neurobiol 2017; 160:64-81. [PMID: 29102670 PMCID: PMC5773077 DOI: 10.1016/j.pneurobio.2017.10.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 10/09/2017] [Accepted: 10/21/2017] [Indexed: 12/12/2022]
Abstract
Preclinical and clinical neurophysiological and neurorehabilitation research has generated rather surprising levels of recovery of volitional sensory-motor function in persons with chronic motor paralysis following a spinal cord injury. The key factor in this recovery is largely activity-dependent plasticity of spinal and supraspinal networks. This key factor can be triggered by neuromodulation of these networks with electrical and pharmacological interventions. This review addresses some of the systems-level physiological mechanisms that might explain the effects of electrical modulation and how repetitive training facilitates the recovery of volitional motor control. In particular, we substantiate the hypotheses that: (1) in the majority of spinal lesions, a critical number and type of neurons in the region of the injury survive, but cannot conduct action potentials, and thus are electrically non-responsive; (2) these neuronal networks within the lesioned area can be neuromodulated to a transformed state of electrical competency; (3) these two factors enable the potential for extensive activity-dependent reorganization of neuronal networks in the spinal cord and brain, and (4) propriospinal networks play a critical role in driving this activity-dependent reorganization after injury. Real-time proprioceptive input to spinal networks provides the template for reorganization of spinal networks that play a leading role in the level of coordination of motor pools required to perform a given functional task. Repetitive exposure of multi-segmental sensory-motor networks to the dynamics of task-specific sensory input as occurs with repetitive training can functionally reshape spinal and supraspinal connectivity thus re-enabling one to perform complex motor tasks, even years post injury.
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Affiliation(s)
- G Taccola
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Neuroscience Department, International School for Advanced Studies (SISSA), Bonomea 265, Trieste, Italy
| | - D Sayenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - P Gad
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Y Gerasimenko
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Pavlov Institute of Physiology, St. Petersburg 199034, Russia
| | - V R Edgerton
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA; Department of Neurobiology, University of California, Los Angeles, CA 90095 USA; Department of Neurosurgery, University of California, Los Angeles, CA 90095 USA; Brain Research Institute, University of California, Los Angeles, CA 90095 USA; The Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, 2007 NSW, Australia; Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscrit a la Universitat Autònoma de Barcelona, Barcelona, 08916 Badalona, Spain.
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219
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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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220
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Condamine S, Lavoie R, Verdier D, Kolta A. Functional rhythmogenic domains defined by astrocytic networks in the trigeminal main sensory nucleus. Glia 2017; 66:311-326. [DOI: 10.1002/glia.23244] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 09/07/2017] [Accepted: 09/25/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Steven Condamine
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
- Département de Neurosciences; Université de Montréal, Pavillon Paul-G.Desmarais, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
| | - Raphaël Lavoie
- Douglas Mental Health University Institute, 6875 boulevard LaSalle; Montreal Québec H4H 1R3 Canada
| | - Dorly Verdier
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
- Département de Neurosciences; Université de Montréal, Pavillon Paul-G.Desmarais, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
| | - Arlette Kolta
- Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
- Département de Neurosciences; Université de Montréal, Pavillon Paul-G.Desmarais, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
- Faculté de Médecine Dentaire, Université de Montréal, C.P. 6128, succursale Centre-ville; Montréal Québec H3C 3J7 Canada
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221
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A role for the purinergic receptor P2X 3 in astrocytes in the mechanism of craniofacial neuropathic pain. Sci Rep 2017; 7:13627. [PMID: 29051582 PMCID: PMC5648840 DOI: 10.1038/s41598-017-13561-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/26/2017] [Indexed: 11/18/2022] Open
Abstract
The purinergic receptor P2X3, expressed in the central terminals of primary nociceptive neurons in the brainstem, plays an important role in pathological pain. However, little is known about expression of P2X3 in the brainstem astrocytes and its involvement in craniofacial pathologic pain. To address this issue, we investigated the expression of P2X3 in astrocytes in the trigeminal caudal nucleus (Vc) in a rat model of craniofacial neuropathic pain, chronic constriction injury of infraorbital nerve (CCI-ION). We found that 1) P2X3-immunoreactivity is observed in the brainstem astrocytes, preferentially in their fine processes, 2) the number of P2X3-positive fine astrocytic processes and the density of P2X3 in these processes were increased significantly in CCI-ION rats, compared to control rats, and 3) administration of MPEP, a specific mGluR5 antagonist, alleviated the mechanical allodynia and abolished the increase in density of P2X3 in fine astrocytic processes caused by CCI-ION. These findings reveal preferential expression of P2X3 in the fine astrocytic processes in the brainstem, propose a novel role of P2X3 in the fine astrocytic process in the mechanism of craniofacial neuropathic pain, and suggest that the expression of astrocytic P2X3 may be regulated by astrocytic mGluR5.
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222
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Acton D, Miles GB. Gliotransmission and adenosinergic modulation: insights from mammalian spinal motor networks. J Neurophysiol 2017; 118:3311-3327. [PMID: 28954893 DOI: 10.1152/jn.00230.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Astrocytes are proposed to converse with neurons at tripartite synapses, detecting neurotransmitter release and responding with release of gliotransmitters, which in turn modulate synaptic strength and neuronal excitability. However, a paucity of evidence from behavioral studies calls into question the importance of gliotransmission for the operation of the nervous system in healthy animals. Central pattern generator (CPG) networks in the spinal cord and brain stem coordinate the activation of muscles during stereotyped activities such as locomotion, inspiration, and mastication and may therefore provide tractable models in which to assess the contribution of gliotransmission to behaviorally relevant neural activity. We review evidence for gliotransmission within spinal locomotor networks, including studies indicating that adenosine derived from astrocytes regulates the speed of locomotor activity via metamodulation of dopamine signaling.
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Affiliation(s)
- David Acton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
| | - Gareth B Miles
- School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife , United Kingdom
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223
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Schwarz Y, Zhao N, Kirchhoff F, Bruns D. Astrocytes control synaptic strength by two distinct v-SNARE-dependent release pathways. Nat Neurosci 2017; 20:1529-1539. [PMID: 28945220 DOI: 10.1038/nn.4647] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 08/24/2017] [Indexed: 12/11/2022]
Abstract
Communication between glia cells and neurons is crucial for brain functions, but the molecular mechanisms and functional consequences of gliotransmission remain enigmatic. Here we report that astrocytes express synaptobrevin II and cellubrevin as functionally non-overlapping vesicular SNARE proteins on glutamatergic vesicles and neuropeptide Y-containing large dense-core vesicles, respectively. Using individual null-mutants for Vamp2 (synaptobrevin II) and Vamp3 (cellubrevin), as well as the corresponding compound null-mutant for genes encoding both v-SNARE proteins, we delineate previously unrecognized individual v-SNARE dependencies of astrocytic release processes and their functional impact on neuronal signaling. Specifically, we show that astroglial cellubrevin-dependent neuropeptide Y secretion diminishes synaptic signaling, while synaptobrevin II-dependent glutamate release from astrocytes enhances synaptic signaling. Our experiments thereby uncover the molecular mechanisms of two distinct v-SNARE-dependent astrocytic release pathways that oppositely control synaptic strength at presynaptic sites, elucidating new avenues of communication between astrocytes and neurons.
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Affiliation(s)
- Yvonne Schwarz
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Na Zhao
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Dieter Bruns
- Molecular Neurophysiology, Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
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224
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Synapse-specific astrocyte gating of amygdala-related behavior. Nat Neurosci 2017; 20:1540-1548. [PMID: 28945222 DOI: 10.1038/nn.4649] [Citation(s) in RCA: 197] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 08/30/2017] [Indexed: 12/12/2022]
Abstract
The amygdala plays key roles in fear and anxiety. Studies of the amygdala have largely focused on neuronal function and connectivity. Astrocytes functionally interact with neurons, but their role in the amygdala remains largely unknown. We show that astrocytes in the medial subdivision of the central amygdala (CeM) determine the synaptic and behavioral outputs of amygdala circuits. To investigate the role of astrocytes in amygdala-related behavior and identify the underlying synaptic mechanisms, we used exogenous or endogenous signaling to selectively activate CeM astrocytes. Astrocytes depressed excitatory synapses from basolateral amygdala via A1 adenosine receptor activation and enhanced inhibitory synapses from the lateral subdivision of the central amygdala via A2A receptor activation. Furthermore, astrocytic activation decreased the firing rate of CeM neurons and reduced fear expression in a fear-conditioning paradigm. Therefore, we conclude that astrocyte activity determines fear responses by selectively regulating specific synapses, which indicates that animal behavior results from the coordinated activity of neurons and astrocytes.
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225
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A Cross Talk between Neuronal Urokinase-type Plasminogen Activator (uPA) and Astrocytic uPA Receptor (uPAR) Promotes Astrocytic Activation and Synaptic Recovery in the Ischemic Brain. J Neurosci 2017; 37:10310-10322. [PMID: 28931568 DOI: 10.1523/jneurosci.1630-17.2017] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/25/2017] [Accepted: 09/12/2017] [Indexed: 12/22/2022] Open
Abstract
Urokinase-type plasminogen activator (uPA) is a serine proteinase that, upon binding to its receptor (uPAR), catalyzes the conversion of plasminogen into plasmin on the cell surface. Our previous studies indicate that uPA and uPAR expression increase in the ischemic brain during the recovery phase from an acute ischemic injury and that uPA binding to uPAR promotes neurological recovery after an acute ischemic stroke. Here, we used male mice genetically deficient on either uPA (uPA-/-) or uPAR (uPAR-/-) or with a four-amino acid substitution into the growth factor domain of uPA that abrogates its binding to uPAR (PlatGFDhu/GFDhu) to investigate the mechanism whereby uPA promotes neurorepair in the ischemic brain. We found that neurons release uPA and astrocytes recruit uPAR to their plasma membrane during the recovery phase from a hypoxic injury and that binding of neuronal uPA to astrocytic uPAR induces astrocytic activation by a mechanism that does not require plasmin generation, but instead is mediated by extracellular signal-regulated kinase 1/2 (ERK1/2)-regulated phosphorylation of the signal transducer and activator of transcription 3 (STAT3). We report that uPA/uPAR binding is necessary and sufficient to induce astrocytic activation in the ischemic brain and that astrocytes activated by neuronal uPA promote synaptic recovery in neurons that have suffered an acute hypoxic injury via a mechanism mediated by astrocytic thrombospondin-1 (TSP1) and synaptic low-density lipoprotein receptor-related protein-1 (LRP1). In summary, we show that uPA/uPAR-induced astrocytic activation mediates a cross talk between astrocytes and injured neurons that promotes synaptic recovery in the ischemic brain.SIGNIFICANCE STATEMENT To date, there is no therapeutic strategy to promote synaptic recovery in the injured brain. Here, we show that neurons release urokinase-type plasminogen activator (uPA) and astrocytes recruit the uPA receptor (uPAR) to their plasma membrane during the recovery phase from a hypoxic injury. We found that binding of neuronal uPA to astrocytic uPAR promotes astrocytic activation and that astrocytes activated by uPA-uPAR binding promote synaptic recovery in neurons that have suffered a hypoxic injury by a mechanism that does not require plasmin generation, but instead is mediated by ERK1/2-regulated STAT3 phosphorylation, astrocytic thrombospondin-1 (TSP1) and synaptic low-density lipoprotein receptor-related protein-1 (LRP1). Our work unveils a new biological function for uPA-uPAR as mediator of a neuron-astrocyte cross talk that promotes synaptic recovery in the ischemic brain.
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226
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Dynamics of surface neurotransmitter receptors and transporters in glial cells: Single molecule insights. Cell Calcium 2017; 67:46-52. [PMID: 29029790 DOI: 10.1016/j.ceca.2017.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 11/22/2022]
Abstract
The surface dynamics of neurotransmitter receptors and transporters, as well as ion channels, has been well-documented in neurons, revealing complex molecular behaviour and key physiological functions. However, our understanding of the membrane trafficking and dynamics of the signalling molecules located at the plasma membrane of glial cells is still in its infancy. Yet, recent breakthroughs in the field of glial cells have been obtained using combination of superresolution microscopy, single molecule imaging, and electrophysiological recordings. Here, we review our current knowledge on the surface dynamics of neurotransmitter receptors, transporters and ion channels, in glial cells. It has emerged that the brain cell network activity, synaptic activity, and calcium signalling, regulate the surface distribution and dynamics of these molecules. Remarkably, the dynamics of a given neurotransmitter receptor/transporter at the plasma membrane of a glial cell or neuron is unique, revealing the existence of cell-type specific regulatory pathways. Thus, investigating the dynamics of signalling proteins at the surface of glial cells will likely shed new light on our understanding of glial cell physiology and pathology.
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227
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Neuronal P2X7 Receptors Revisited: Do They Really Exist? J Neurosci 2017; 37:7049-7062. [PMID: 28747388 DOI: 10.1523/jneurosci.3103-16.2017] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/22/2017] [Accepted: 05/24/2017] [Indexed: 12/13/2022] Open
Abstract
P2X7 receptors (Rs) constitute a subclass of ATP-sensitive ionotropic receptors (P2X1-P2X7). P2X7Rs have many distinguishing features, mostly based on their long intracellular C terminus regulating trafficking to the cell membrane, protein-protein interactions, and post-translational modification. Their C-terminal tail is especially important in enabling the transition from the nonselective ion channel mode to a membrane pore allowing the passage of large molecules. There is an ongoing dispute on the existence of neuronal P2X7Rs with consequences for our knowledge on their involvement in neuroinflammation, aggravating stroke, temporal lobe epilepsy, neuropathic pain, and various neurodegenerative diseases. Whereas early results appeared to support the operation of P2X7Rs at neurons, more recently glial P2X7Rs are increasingly considered as indirect causes of neuronal effects. Specific tools for P2X7Rs are of limited value because of the poor selectivity of agonists, and the inherent failure of antibodies to differentiate between the large number of active and inactive splice variants, or gain-of-function and loss-of-function small nucleotide polymorphisms of the receptor. Unfortunately, the available P2RX7 knock-out mice generated by pharmaceutical companies possess certain splice variants, which evade inactivation. In view of the recently discovered bidirectional dialogue between astrocytes and neurons (and even microglia and neurons), we offer an alternative explanation for previous data, which assumedly support the existence of P2X7Rs at neurons. We think that the unbiased reader will follow our argumentation on astrocytic or microglial P2X7Rs being the primary targets of pathologically high extracellular ATP concentrations, although a neuronal localization of these receptors cannot be fully excluded either.
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228
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Pitt J, Wilcox KC, Tortelli V, Diniz LP, Oliveira MS, Dobbins C, Yu XW, Nandamuri S, Gomes FCA, DiNunno N, Viola KL, De Felice FG, Ferreira ST, Klein WL. Neuroprotective astrocyte-derived insulin/insulin-like growth factor 1 stimulates endocytic processing and extracellular release of neuron-bound Aβ oligomers. Mol Biol Cell 2017; 28:2623-2636. [PMID: 28963439 PMCID: PMC5620371 DOI: 10.1091/mbc.e17-06-0416] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/31/2017] [Indexed: 12/19/2022] Open
Abstract
Synaptopathy underlying memory deficits in Alzheimer's disease (AD) is increasingly thought to be instigated by toxic oligomers of the amyloid beta peptide (AβOs). Given the long latency and incomplete penetrance of AD dementia with respect to Aβ pathology, we hypothesized that factors present in the CNS may physiologically protect neurons from the deleterious impact of AβOs. Here we employed physically separated neuron-astrocyte cocultures to investigate potential non-cell autonomous neuroprotective factors influencing AβO toxicity. Neurons cultivated in the absence of an astrocyte feeder layer showed abundant AβO binding to dendritic processes and associated synapse deterioration. In contrast, neurons in the presence of astrocytes showed markedly reduced AβO binding and synaptopathy. Results identified the protective factors released by astrocytes as insulin and insulin-like growth factor-1 (IGF1). The protective mechanism involved release of newly bound AβOs into the extracellular medium dependent upon trafficking that was sensitive to exosome pathway inhibitors. Delaying insulin treatment led to AβO binding that was no longer releasable. The neuroprotective potential of astrocytes was itself sensitive to chronic AβO exposure, which reduced insulin/IGF1 expression. Our findings support the idea that physiological protection against synaptotoxic AβOs can be mediated by astrocyte-derived insulin/IGF1, but that this protection itself is vulnerable to AβO buildup.
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Affiliation(s)
- Jason Pitt
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208.,Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Kyle C Wilcox
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
| | - Vanessa Tortelli
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil
| | - Luan Pereira Diniz
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil
| | - Maira S Oliveira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil
| | - Cassandra Dobbins
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
| | - Xiao-Wen Yu
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Sathwik Nandamuri
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
| | - Flávia C A Gomes
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil
| | - Nadia DiNunno
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
| | - Kirsten L Viola
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
| | - Fernanda G De Felice
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil.,Centre for Neuroscience Studies, Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Sergio T Ferreira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil.,Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro RJ 21944-590, Brazil
| | - William L Klein
- Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208
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229
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Modulation of Central Synapses by Astrocyte-Released ATP and Postsynaptic P2X Receptors. Neural Plast 2017; 2017:9454275. [PMID: 28845311 PMCID: PMC5563405 DOI: 10.1155/2017/9454275] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/10/2017] [Indexed: 01/14/2023] Open
Abstract
Communication between neuronal and glial cells is important for neural plasticity. P2X receptors are ATP-gated cation channels widely expressed in the brain where they mediate action of extracellular ATP released by neurons and/or glia. Recent data show that postsynaptic P2X receptors underlie slow neuromodulatory actions rather than fast synaptic transmission at brain synapses. Here, we review these findings with a particular focus on the release of ATP by astrocytes and the diversity of postsynaptic P2X-mediated modulation of synaptic strength and plasticity in the CNS.
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230
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Bannai H. Molecular membrane dynamics: Insights into synaptic function and neuropathological disease. Neurosci Res 2017; 129:47-56. [PMID: 28826905 DOI: 10.1016/j.neures.2017.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/14/2017] [Accepted: 07/26/2017] [Indexed: 11/19/2022]
Abstract
The fluid mosaic model states that molecules in the plasma membrane can freely undergo lateral diffusion; however, in neurons and glia, specific membrane molecules are concentrated in cellular microdomains to overcome the randomizing effects of free diffusion. This specialized distribution of membrane molecules is crucial for various cell functions; one example is the accumulation of neurotransmitter receptors at the postsynaptic neuronal membrane, which enables efficient synaptic transmission. Quantum dot-single particle tracking (QD-SPT) is a super-resolution imaging technique that uses semiconductor nanocrystal quantum dots as fluorescent probes, and is a powerful tool for analyzing protein and lipid behavior in the plasma membrane. In this article, we review studies implementing QD-SPT in neuroscience research and important data gleaned using this technology. Recent QD-SPT experiments have provided critical insights into the mechanism and physiological relevance of membrane self-organization in neurons and astrocytes in the brain. The mobility of some membrane molecules may become abnormal in cellular models of epilepsy and Alzheimer's disease. Based on these findings, we propose that the behavior of membrane molecules reflects the condition of neurons in pathological disease states.
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Affiliation(s)
- Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
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231
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Steady-State Free Ca 2+ in Astrocytes Is Decreased by Experience and Impacts Arteriole Tone. J Neurosci 2017; 37:8150-8165. [PMID: 28733356 DOI: 10.1523/jneurosci.0239-17.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 06/23/2017] [Accepted: 07/10/2017] [Indexed: 12/27/2022] Open
Abstract
Astrocytes can control basal synaptic strength and arteriole tone via their resting Ca2+ activity. However, whether resting astrocyte Ca2+ can adjust to a new steady-state level, with an impact on surrounding brain cells, remains unknown. Using two-photon Ca2+ imaging in male rat acute brain slices of the somatosensory neocortex, we found that theta burst neural activity produced an unexpected long-lasting reduction in astrocyte free Ca2+ in the soma and endfeet. The drop in intracellular Ca2+ was attenuated by antagonists targeting multiple ionotropic and metabotropic glutamate receptors, and intracellular cascades involved Ca2+ stores and nitric oxide. The reduction in astrocyte endfoot Ca2+ was coincident with an increase in arteriole tone, and both the Ca2+ drop and the tone change were prevented by an NMDA receptor antagonist. Astrocyte patch-clamp experiments verified that the glutamate receptors in question were located on astrocytes and that Ca2+ changes within astrocytes were responsible for the long-lasting change in arteriole diameter caused by theta burst neural activity. In astrocytes from animals that lived in an enriched environment, we measured a relatively lower resting Ca2+ level that occluded any further drop in Ca2+ in response to theta burst activity. These data suggest that electrically evoked patterns of neural activity or natural experience can adjust steady-state resting astrocyte Ca2+ and that the effect has an impact on basal arteriole diameter.SIGNIFICANCE STATEMENT The field of astrocyte-neuron and astrocyte-arteriole interactions is currently in a state of refinement. Experimental evidence ex vivo suggests that direct manipulation of astrocyte-free Ca2+ regulates synaptic signaling and local blood flow control; however, in vivo experiments fail to link synaptically evoked astrocyte Ca2+ transients and immediate changes to various astrocyte-mediated processes. To clarify this discrepancy, we examined a different aspect of astrocyte Ca2+: the resting, steady-state free Ca2+ of astrocytes, its modulation, and its potential role in the tonic regulation of surrounding brain cells. We found that ex vivo or in vivo neural activity induced a long-lasting reduction in resting free astrocyte Ca2+ and that this phenomenon changed arteriole tone.
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232
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Sobrinho CR, Gonçalves CM, Takakura AC, Mulkey DK, Moreira TS. Fluorocitrate-mediated depolarization of astrocytes in the retrotrapezoid nucleus stimulates breathing. J Neurophysiol 2017; 118:1690-1697. [PMID: 28679838 DOI: 10.1152/jn.00032.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 06/05/2017] [Accepted: 06/20/2017] [Indexed: 12/31/2022] Open
Abstract
Evidence indicates that CO2/H+-evoked ATP released from retrotrapezoid nucleus (RTN) astrocytes modulates the activity of CO2-sensitive neurons. RTN astrocytes also sense H+ by inhibition of Kir4.1 channels; however, the relevance of this pH-sensitive current remains unclear since ATP release appears to involve CO2-dependent gating of connexin 26 hemichannels. Considering that depolarization mediated by H+ inhibition of Kir4.1 channels is expected to increase sodium bicarbonate cotransporter (NBC) conductance and favor Ca2+ influx via the sodium calcium exchanger (NCX), we hypothesize that depolarization in the presence of CO2 is sufficient to facilitate ATP release and enhance respiratory output. Here, we confirmed that acute exposure to fluorocitrate (FCt) reversibly depolarizes RTN astrocytes and increased activity of RTN neurons by a purinergic-dependent mechanism. We then made unilateral injections of FCt into the RTN or two other putative chemoreceptor regions (NTS and medullary raphe) to depolarize astrocytes under control conditions and during P2-recepetor blockade while measuring cardiorespiratory activities in urethane-anesthetized, vagotomized, artificially ventilated male Wistar rats. Unilateral injection of FCt into the RTN increased phrenic (PNA) amplitude and frequency without changes in arterial pressure. Unilateral injection of pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS, a P2-receptor antagonist) into the RTN dampened both PNA amplitude and frequency responses to FCt. Injection of MRS2179 (P2Y1-receptor antagonist) into the RTN did not affect the FCt-induced respiratory responses. Fluorocitrate had no effect on breathing when injected into the NTS or raphe. These results suggest that depolarization can facilitate purinergic enhancement of respiratory drive from the RTN.NEW & NOTEWORTHY Astrocytes in the retrotrapezoid nucleus (RTN) are known to function as respiratory chemoreceptors; however, it is not clear whether changes in voltage contribute to astrocyte chemoreception. We showed that depolarization of RTN astrocytes at constant CO2 levels is sufficient to modulate RTN chemoreception by a purinergic-dependent mechanism. These results support the possibility that astrocyte depolarization can facilitate purinergic enhancement of respiratory drive from the RTN.
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Affiliation(s)
- Cleyton R Sobrinho
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil
| | - Christopher M Gonçalves
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - Ana C Takakura
- Department of Pharmacology, University of São Paulo, São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; and
| | - Thiago S Moreira
- Department of Physiology and Biophysics, University of São Paulo, São Paulo, Brazil;
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233
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Crompton LA, Cordero‐Llana O, Caldwell MA. Astrocytes in a dish: Using pluripotent stem cells to model neurodegenerative and neurodevelopmental disorders. Brain Pathol 2017; 27:530-544. [PMID: 28585380 PMCID: PMC8028895 DOI: 10.1111/bpa.12522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 04/27/2017] [Indexed: 02/06/2023] Open
Abstract
Neuroscience and Neurobiology have historically been neuron biased, yet up to 40% of the cells in the brain are astrocytes. These cells are heterogeneous and regionally diverse but universally essential for brain homeostasis. Astrocytes regulate synaptic transmission as part of the tripartite synapse, provide metabolic and neurotrophic support, recycle neurotransmitters, modulate blood flow and brain blood barrier permeability and are implicated in the mechanisms of neurodegeneration. Using pluripotent stem cells (PSC), it is now possible to study regionalised human astrocytes in a dish and to model their contribution to neurodevelopmental and neurodegenerative disorders. The evidence challenging the traditional neuron-centric view of degeneration within the CNS is reviewed here, with focus on recent findings and disease phenotypes from human PSC-derived astrocytes. In addition we compare current protocols for the generation of regionalised astrocytes and how these can be further refined by our growing knowledge of neurodevelopment. We conclude by proposing a functional and phenotypical characterisation of PSC-derived astrocytic cultures that is critical for reproducible and robust disease modelling.
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Affiliation(s)
- Lucy A. Crompton
- School of Biochemistry, Medical Sciences BldUniversity of BristolBristolBS8 1TDUK
| | - Oscar Cordero‐Llana
- Bristol Medical School, Medical Sciences BldUniversity of BristolBristolBS8 1TDUK
| | - Maeve A. Caldwell
- Trinity College Institute for NeuroscienceTrinity College Dublin 2Ireland
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234
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Neural Activity-Dependent Regulation of Radial Glial Filopodial Motility Is Mediated by Glial cGMP-Dependent Protein Kinase 1 and Contributes to Synapse Maturation in the Developing Visual System. J Neurosci 2017; 36:5279-88. [PMID: 27170125 DOI: 10.1523/jneurosci.3787-15.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 03/30/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Radial glia in the developing optic tectum extend highly dynamic filopodial protrusions within the tectal neuropil, the motility of which has previously been shown to be sensitive to neural activity and nitric oxide (NO) release. Using in vivo two-photon microscopy, we performed time-lapse imaging of radial glial cells and measured filopodial motility in the intact albino Xenopus laevis tadpole. Application of MK801 to block neuronal NMDA receptor (NMDAR) currents confirmed a significant reduction in radial glial filopodial motility. This reduction did not occur in glial cells expressing a dominant-negative form of cGMP-dependent protein kinase 1 (PKG1), and was prevented by elevation of cGMP levels with the phosphodiesterase type 5 inhibitor sildenafil. These results suggest that neuronal NMDAR activation results in the release of NO, which in turn modulates PKG1 activation in glial cells to control filopodial motility. We further showed that interfering with the function of the small GTPases Rac1 or RhoA, known to be regulated by PKG1 phosphorylation, decreased motility or eliminated filopodial processes respectively. These manipulations led to profound defects in excitatory synaptic development and maturation of neighboring neurons. SIGNIFICANCE STATEMENT Radial glia in the developing brain extend motile filopodia from their primary stalk. Neuronal NMDA receptor activity controls glial motility through intercellular activation of cGMP-dependent protein kinase 1 (PKG1) signaling in glial cells. Manipulating PKG1, Rac1, or RhoA signaling in radial glia in vivo to eliminate glial filopodia or impair glial motility profoundly impacted synaptogenesis and circuit maturation.
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235
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Sleep loss and structural plasticity. Curr Opin Neurobiol 2017; 44:1-7. [DOI: 10.1016/j.conb.2016.12.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/21/2016] [Indexed: 12/14/2022]
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236
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Adamsky A, Goshen I. Astrocytes in Memory Function: Pioneering Findings and Future Directions. Neuroscience 2017; 370:14-26. [PMID: 28571720 DOI: 10.1016/j.neuroscience.2017.05.033] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/05/2017] [Accepted: 05/19/2017] [Indexed: 12/29/2022]
Abstract
Astrocytes have been generally believed to perform mainly homeostatic and supportive functions for neurons in the central nervous system. Recently, a growing body of evidence suggests previously unrecognized and surprising functions for astrocytes, including regulation of synaptic formation, transmission and plasticity, all of which are considered as the infrastructure for information processing and memory formation and stabilization. This review discusses the involvement of astrocytes in memory functions and the possible mechanisms that may underlie it. We review the important breakthroughs obtained in this field, as well as some of the controversies that arose from the past difficulty to manipulate these cells in a cell type-specific and non-invasive manner. Finally, we present new research avenues based on the advanced tools becoming available in recent years: optogenetics and chemogenetics, and the potential ways in which these tools may further illuminate the role of astrocytes in memory processes.
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Affiliation(s)
- Adar Adamsky
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Givat Ram, Jerusalem 91904, Israel
| | - Inbal Goshen
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University, Givat Ram, Jerusalem 91904, Israel.
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237
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Bindocci E, Savtchouk I, Liaudet N, Becker D, Carriero G, Volterra A. Three-dimensional Ca2+imaging advances understanding of astrocyte biology. Science 2017; 356:356/6339/eaai8185. [DOI: 10.1126/science.aai8185] [Citation(s) in RCA: 193] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 04/12/2017] [Indexed: 11/02/2022]
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238
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Losi G, Mariotti L, Sessolo M, Carmignoto G. New Tools to Study Astrocyte Ca 2+ Signal Dynamics in Brain Networks In Vivo. Front Cell Neurosci 2017; 11:134. [PMID: 28536505 PMCID: PMC5422467 DOI: 10.3389/fncel.2017.00134] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 04/20/2017] [Indexed: 11/19/2022] Open
Abstract
Sensory information processing is a fundamental operation in the brain that is based on dynamic interactions between different neuronal populations. Astrocytes, a type of glial cells, have been proposed to represent active elements of brain microcircuits that, through dynamic interactions with neurons, provide a modulatory control of neuronal network activity. Specifically, astrocytes in different brain regions have been described to respond to neuronal signals with intracellular Ca2+ elevations that represent a key step in the functional recruitment of astrocytes to specific brain circuits. Accumulating evidence shows that Ca2+ elevations regulate the release of gliotransmitters that, in turn, modulate synaptic transmission and neuronal excitability. Recent studies also provided new insights into the spatial and temporal features of astrocytic Ca2+ elevations revealing a surprising complexity of Ca2+ signal dynamics in astrocytes. Here we discuss how recently developed experimental tools such as the genetically encoded Ca2+ indicators (GECI), optogenetics and chemogenetics can be applied to the study of astrocytic Ca2+ signals in the living brain.
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Affiliation(s)
- Gabriele Losi
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of PadovaPadova, Italy
| | - Letizia Mariotti
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of PadovaPadova, Italy.,Division of Neurobiology, MRC Laboratory of Molecular BiologyCambridge, UK
| | - Michele Sessolo
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of PadovaPadova, Italy.,Center for Drug Discovery & Development, Aptuit inc.Verona, Italy
| | - Giorgio Carmignoto
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of PadovaPadova, Italy
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239
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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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240
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Wang Q, Jie W, Liu JH, Yang JM, Gao TM. An astroglial basis of major depressive disorder? An overview. Glia 2017; 65:1227-1250. [DOI: 10.1002/glia.23143] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 02/26/2017] [Accepted: 02/27/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Qian Wang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, Southern Medical University; Guangzhou 510515 China
| | - Wei Jie
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, Southern Medical University; Guangzhou 510515 China
| | - Ji-Hong Liu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, Southern Medical University; Guangzhou 510515 China
| | - Jian-Ming Yang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, Southern Medical University; Guangzhou 510515 China
| | - Tian-Ming Gao
- State Key Laboratory of Organ Failure Research, Key Laboratory of Psychiatric Disorders of Guangdong Province, Collaborative Innovation Center for Brain Science, Department of Neurobiology, Southern Medical University; Guangzhou 510515 China
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241
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Buscemi L, Ginet V, Lopatar J, Montana V, Pucci L, Spagnuolo P, Zehnder T, Grubišić V, Truttman A, Sala C, Hirt L, Parpura V, Puyal J, Bezzi P. Homer1 Scaffold Proteins Govern Ca2+ Dynamics in Normal and Reactive Astrocytes. Cereb Cortex 2017; 27:2365-2384. [PMID: 27075036 PMCID: PMC5963825 DOI: 10.1093/cercor/bhw078] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In astrocytes, the intracellular calcium (Ca2+) signaling mediated by activation of metabotropic glutamate receptor 5 (mGlu5) is crucially involved in the modulation of many aspects of brain physiology, including gliotransmission. Here, we find that the mGlu5-mediated Ca2+ signaling leading to release of glutamate is governed by mGlu5 interaction with Homer1 scaffolding proteins. We show that the long splice variants Homer1b/c are expressed in astrocytic processes, where they cluster with mGlu5 at sites displaying intense local Ca2+ activity. We show that the structural and functional significance of the Homer1b/c-mGlu5 interaction is to relocate endoplasmic reticulum (ER) to the proximity of the plasma membrane and to optimize Ca2+ signaling and glutamate release. We also show that in reactive astrocytes the short dominant-negative splice variant Homer1a is upregulated. Homer1a, by precluding the mGlu5-ER interaction decreases the intensity of Ca2+ signaling thus limiting the intensity and the duration of glutamate release by astrocytes. Hindering upregulation of Homer1a with a local injection of short interfering RNA in vivo restores mGlu5-mediated Ca2+ signaling and glutamate release and sensitizes astrocytes to apoptosis. We propose that Homer1a may represent one of the cellular mechanisms by which inflammatory astrocytic reactions are beneficial for limiting brain injury.
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Affiliation(s)
- Lara Buscemi
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, University Hospital Centre and University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Vanessa Ginet
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
- Division of Neonatology, Department of Paediatrics and Paediatric Surgery, University Hospital Centre and University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Jan Lopatar
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
| | - Vedrana Montana
- Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy and Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Luca Pucci
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
| | - Paola Spagnuolo
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy
| | - Tamara Zehnder
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
| | - Vladimir Grubišić
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy and Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Anita Truttman
- Division of Neonatology, Department of Paediatrics and Paediatric Surgery, University Hospital Centre and University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Carlo Sala
- CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Lorenz Hirt
- Stroke Laboratory, Neurology Service, Department of Clinical Neurosciences, University Hospital Centre and University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy and Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
- Division of Neonatology, Department of Paediatrics and Paediatric Surgery, University Hospital Centre and University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Paola Bezzi
- Department of Fundamental Neurosciences, University of Lausanne, CH1005Lausanne, Switzerland
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242
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Kwon J, An H, Sa M, Won J, Shin JI, Lee CJ. Orai1 and Orai3 in Combination with Stim1 Mediate the Majority of Store-operated Calcium Entry in Astrocytes. Exp Neurobiol 2017; 26:42-54. [PMID: 28243166 PMCID: PMC5326714 DOI: 10.5607/en.2017.26.1.42] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 01/31/2017] [Accepted: 01/31/2017] [Indexed: 01/06/2023] Open
Abstract
Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca2+) level. Therefore, maintaining the intracellular Ca2+ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca2+ homeostasis in astrocytes is the store-operated Ca2+ entry (SOCE). This process is mediated by a combination of the Ca2+-store-depletion-sensor, Stim, and the store-operated Ca2+-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca2+-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca2+-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.
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Affiliation(s)
- Jea Kwon
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Heeyoung An
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Moonsun Sa
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - Joungha Won
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Department of Biological Science, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jeong Im Shin
- Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea.; Center for Neuroscience and Functional Connectomics, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea.; Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
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243
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Gómez-Gonzalo M, Martin-Fernandez M, Martínez-Murillo R, Mederos S, Hernández-Vivanco A, Jamison S, Fernandez AP, Serrano J, Calero P, Futch HS, Corpas R, Sanfeliu C, Perea G, Araque A. Neuron-astrocyte signaling is preserved in the aging brain. Glia 2017; 65:569-580. [PMID: 28130845 DOI: 10.1002/glia.23112] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 11/23/2016] [Accepted: 12/21/2016] [Indexed: 12/18/2022]
Abstract
Astrocytes play crucial roles in brain homeostasis and are emerging as regulatory elements of neuronal and synaptic physiology by responding to neurotransmitters with Ca2+ elevations and releasing gliotransmitters that activate neuronal receptors. Aging involves neuronal and astrocytic alterations, being considered risk factor for neurodegenerative diseases. Most evidence of the astrocyte-neuron signaling is derived from studies with young animals; however, the features of astrocyte-neuron signaling in adult and aging brain remain largely unknown. We have investigated the existence and properties of astrocyte-neuron signaling in physiologically and pathologically aging mouse hippocampal and cortical slices at different lifetime points (0.5 to 20 month-old animals). We found that astrocytes preserved their ability to express spontaneous and neurotransmitter-dependent intracellular Ca2+ signals from juvenile to aging brains. Likewise, resting levels of gliotransmission, assessed by neuronal NMDAR activation by glutamate released from astrocytes, were largely preserved with similar properties in all tested age groups, but DHPG-induced gliotransmission was reduced in aged mice. In contrast, gliotransmission was enhanced in the APP/PS1 mouse model of Alzheimer's disease, indicating a dysregulation of astrocyte-neuron signaling in pathological conditions. Disruption of the astrocytic IP3 R2 mediated-signaling, which is required for neurotransmitter-induced astrocyte Ca2+ signals and gliotransmission, boosted the progression of amyloid plaque deposits and synaptic plasticity impairments in APP/PS1 mice at early stages of the disease. Therefore, astrocyte-neuron interaction is a fundamental signaling, largely conserved in the adult and aging brain of healthy animals, but it is altered in Alzheimer's disease, suggesting that dysfunctions of astrocyte Ca2+ physiology may contribute to this neurodegenerative disease. GLIA 2017 GLIA 2017;65:569-580.
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Affiliation(s)
| | | | | | | | | | - Stephanie Jamison
- Department of Neuroscience, University of Minnesota, Minneapolis, 55455
| | | | | | | | - Hunter S Futch
- College of Medicine, University of Florida, Gainesville, Florida, 32610-0261
| | - Rubén Corpas
- Aging and Neurodegeneration Unit, Biomedical Research Institute of Barcelona (IIBB), CSIC and IDIBAPS, Barcelona, 08036, Spain
| | - Coral Sanfeliu
- Aging and Neurodegeneration Unit, Biomedical Research Institute of Barcelona (IIBB), CSIC and IDIBAPS, Barcelona, 08036, Spain
| | | | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, 55455
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244
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Stokes JA, Arbogast TE, Moya EA, Fu Z, Powell FL. Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia. J Neurophysiol 2017; 117:1625-1635. [PMID: 28100653 DOI: 10.1152/jn.00525.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 01/14/2023] Open
Abstract
Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, PiO2 = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly (P < 0.001) decreased ventilation during acute hypoxia in CH rats. However, minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia.NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory centers during chronic hypoxia and ventilatory acclimatization. However, minocycline cannot reverse ventilatory acclimatization after it is established. Hence, glial cells may provide signals that initiate but do not sustain ventilatory acclimatization.
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Affiliation(s)
- Jennifer A Stokes
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Tara E Arbogast
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Esteban A Moya
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Zhenxing Fu
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Frank L Powell
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
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245
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Sherwood MW, Arizono M, Hisatsune C, Bannai H, Ebisui E, Sherwood JL, Panatier A, Oliet SHR, Mikoshiba K. Astrocytic IP 3 Rs: Contribution to Ca 2+ signalling and hippocampal LTP. Glia 2017; 65:502-513. [PMID: 28063222 DOI: 10.1002/glia.23107] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/26/2016] [Accepted: 12/01/2016] [Indexed: 12/22/2022]
Abstract
Astrocytes regulate hippocampal synaptic plasticity by the Ca2+ dependent release of the N-methyl d-aspartate receptor (NMDAR) co-agonist d-serine. Previous evidence indicated that d-serine release would be regulated by the intracellular Ca2+ release channel IP3 receptor (IP3 R), however, genetic deletion of IP3 R2, the putative astrocytic IP3 R subtype, had no impact on synaptic plasticity or transmission. Although IP3 R2 is widely believed to be the only functional IP3 R in astrocytes, three IP3 R subtypes (1, 2, and 3) have been identified in vertebrates. Therefore, to better understand gliotransmission, we investigated the functionality of IP3 R and the contribution of the three IP3 R subtypes to Ca2+ signalling. As a proxy for gliotransmission, we found that long-term potentiation (LTP) was impaired by dialyzing astrocytes with the broad IP3 R blocker heparin, and rescued by exogenous d-serine, indicating that astrocytic IP3 Rs regulate d-serine release. To explore which IP3 R subtypes are functional in astrocytes, we used pharmacology and two-photon Ca2+ imaging of hippocampal slices from transgenic mice (IP3 R2-/- and IP3 R2-/- ;3-/- ). This approach revealed that underneath IP3 R2-mediated global Ca2+ events are an overlooked class of IP3 R-mediated local events, occurring in astroglial processes. Notably, multiple IP3 Rs were recruited by high frequency stimulation of the Schaffer collaterals, a classical LTP induction protocol. Together, these findings show the dependence of LTP and gliotransmission on Ca2+ release by astrocytic IP3 Rs. GLIA 2017;65:502-513.
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Affiliation(s)
- Mark William Sherwood
- INSERM U1215, Neurocentre Magendie, Bordeaux, 33077, France.,Université de Bordeaux, Bordeaux, 33077, France.,Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Misa Arizono
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Chihiro Hisatsune
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Division of Biological Sciences, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8602, Japan
| | - Etsuko Ebisui
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - John Lawrence Sherwood
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Aude Panatier
- INSERM U1215, Neurocentre Magendie, Bordeaux, 33077, France.,Université de Bordeaux, Bordeaux, 33077, France
| | | | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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246
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Buosi AS, Matias I, Araujo APB, Batista C, Gomes FCA. Heterogeneity in Synaptogenic Profile of Astrocytes from Different Brain Regions. Mol Neurobiol 2017; 55:751-762. [PMID: 28050794 DOI: 10.1007/s12035-016-0343-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 12/02/2016] [Indexed: 12/13/2022]
Abstract
Astrocytes, the most abundant glial cells in the central nervous system (CNS), comprise a heterogeneous population of cells. However, how this heterogeneity impacts their function within brain homeostasis and response to injury and disease is still largely unknown. Recently, astrocytes have been recognized as important regulators of synapse formation and maturation. Here, we analyzed the synaptogenic property of astrocytes from different regions of the CNS. The effect of conditioned medium derived from astrocytes (astrocyte-conditioned medium (ACM)) from cerebral cortex, hippocampus, midbrain and cerebellum, in synapse formation, was evaluated. Synapse formation was analyzed by quantification of pre- and postsynaptic proteins, synaptophysin, and postsynaptic density protein 95 (PSD-95). ACM from the four regions increased significantly the number of synaptophysin/PSD-95 puncta on neurons from the same and different brain regions. Differences on astrocytic synaptogenic potential between the regions were observed according to ACM protein concentration. Thus, cerebellar astrocytes have higher synaptogenic effect when ACM is less concentrated. Also, heterotypical co-culture assays revealed that neurons from cerebral cortex and midbrain equally respond to ACM, indicating that differences in synapse effect are unlike to be neuron-autonomous. The expression profile of the synaptogenic molecules secreted by astrocytes from distinct brain regions was analyzed by qPCR. Gene expression of glypicans 4 and 6, hevin, and secreted protein-acidic and rich in cysteine (SPARC) greatly varies between astrocytes from different brain regions. Furthermore, in vivo analysis of hevin protein confirmed that variance. These findings highlight the heterogeneity of astrocytes and suggest that their synaptogenic potential may be different in each brain region, mainly due to distinct gene expression profiles.
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Affiliation(s)
- Andrea Schmidt Buosi
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21941-902, Brazil
| | - Isadora Matias
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21941-902, Brazil
| | - Ana Paula Bergamo Araujo
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21941-902, Brazil
| | - Carolina Batista
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, 21941-902, Brazil
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247
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Perea G, Gómez R, Mederos S, Covelo A, Ballesteros JJ, Schlosser L, Hernández-Vivanco A, Martín-Fernández M, Quintana R, Rayan A, Díez A, Fuenzalida M, Agarwal A, Bergles DE, Bettler B, Manahan-Vaughan D, Martín ED, Kirchhoff F, Araque A. Activity-dependent switch of GABAergic inhibition into glutamatergic excitation in astrocyte-neuron networks. eLife 2016; 5. [PMID: 28012274 PMCID: PMC5231406 DOI: 10.7554/elife.20362] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 12/23/2016] [Indexed: 12/28/2022] Open
Abstract
Interneurons are critical for proper neural network function and can activate Ca2+ signaling in astrocytes. However, the impact of the interneuron-astrocyte signaling into neuronal network operation remains unknown. Using the simplest hippocampal Astrocyte-Neuron network, i.e., GABAergic interneuron, pyramidal neuron, single CA3-CA1 glutamatergic synapse, and astrocytes, we found that interneuron-astrocyte signaling dynamically affected excitatory neurotransmission in an activity- and time-dependent manner, and determined the sign (inhibition vs potentiation) of the GABA-mediated effects. While synaptic inhibition was mediated by GABAA receptors, potentiation involved astrocyte GABAB receptors, astrocytic glutamate release, and presynaptic metabotropic glutamate receptors. Using conditional astrocyte-specific GABAB receptor (Gabbr1) knockout mice, we confirmed the glial source of the interneuron-induced potentiation, and demonstrated the involvement of astrocytes in hippocampal theta and gamma oscillations in vivo. Therefore, astrocytes decode interneuron activity and transform inhibitory into excitatory signals, contributing to the emergence of novel network properties resulting from the interneuron-astrocyte interplay. DOI:http://dx.doi.org/10.7554/eLife.20362.001
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Affiliation(s)
- Gertrudis Perea
- Consejo Superior de Investigaciones Científicas, Instituto Cajal, Madrid, Spain
| | - Ricardo Gómez
- Consejo Superior de Investigaciones Científicas, Instituto Cajal, Madrid, Spain.,Cellular and Systems Neurobiology, Systems Biology Program, Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Sara Mederos
- Consejo Superior de Investigaciones Científicas, Instituto Cajal, Madrid, Spain
| | - Ana Covelo
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Jesús J Ballesteros
- Albacete Science and Technology Park, Institute for Research in Neurological Disabilities, University of Castilla-La Mancha, Albacete, Spain.,Department of Neurophysiology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany
| | - Laura Schlosser
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | | | | | - Ruth Quintana
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Abdelrahman Rayan
- Department of Neurophysiology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany
| | - Adolfo Díez
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
| | - Marco Fuenzalida
- Center of Neurobiology and Brain Plasticity, Institute of Physiology, Faculty of Science, Universidad de Valparaíso, Valparaiso, Chile
| | - Amit Agarwal
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, United States
| | - Dwight E Bergles
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, United States
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Denise Manahan-Vaughan
- Department of Neurophysiology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany
| | - Eduardo D Martín
- Albacete Science and Technology Park, Institute for Research in Neurological Disabilities, University of Castilla-La Mancha, Albacete, Spain
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, United States
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248
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Barros-Barbosa AR, Ferreirinha F, Oliveira Â, Mendes M, Lobo MG, Santos A, Rangel R, Pelletier J, Sévigny J, Cordeiro JM, Correia-de-Sá P. Adenosine A 2A receptor and ecto-5'-nucleotidase/CD73 are upregulated in hippocampal astrocytes of human patients with mesial temporal lobe epilepsy (MTLE). Purinergic Signal 2016; 12:719-734. [PMID: 27650530 PMCID: PMC5124012 DOI: 10.1007/s11302-016-9535-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Refractoriness to existing medications of up to 80 % of the patients with mesial temporal lobe epilepsy (MTLE) prompts for finding new antiepileptic drug targets. The adenosine A2A receptor emerges as an interesting pharmacological target since its excitatory nature partially counteracts the dominant antiepileptic role of endogenous adenosine acting via inhibitory A1 receptors. Gain of function of the excitatory A2A receptor has been implicated in a significant number of brain pathologies commonly characterized by neuronal excitotoxicity. Here, we investigated changes in the expression and cellular localization of the A2A receptor and of the adenosine-generating enzyme, ecto-5'-nucleotidase/CD73, in the hippocampus of control individuals and MTLE human patients. Western blot analysis indicates that the A2A receptor is more abundant in the hippocampus of MTLE patients compared to control individuals. Immunoreactivity against the A2A receptor predominates in astrocytes staining positively for the glial fibrillary acidic protein (GFAP). No co-localization was observed between the A2A receptor and neuronal cell markers, like synaptotagmin 1/2 (nerve terminals) and neurofilament 200 (axon fibers). Hippocampal astrogliosis observed in MTLE patients was accompanied by a proportionate increase in A2A receptor and ecto-5'-nucleotidase/CD73 immunoreactivities. Given our data, we hypothesize that selective blockade of excessive activation of astrocytic A2A receptors and/or inhibition of surplus adenosine formation by membrane-bound ecto-5'-nucleotidase/CD73 may reduce neuronal excitability, thus providing a novel therapeutic target for drug-refractory seizures in MTLE patients.
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Affiliation(s)
- Aurora R Barros-Barbosa
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Fátima Ferreirinha
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Ângela Oliveira
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Marina Mendes
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - M Graça Lobo
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Agostinho Santos
- Serviço de Patologia Forense, Instituto Nacional de Medicina Legal e Ciências Forenses-Delegação do Norte (INMLCF-DN), Porto, Portugal
| | - Rui Rangel
- Serviço de Neurocirurgia, Centro Hospitalar do Porto-Hospital Geral de Santo António (CHP-HGSA), Porto, Portugal
| | - Julie Pelletier
- Centre de Recherche du CHU de Québec-Université Laval, CHUL, QC, Québec, Canada
| | - Jean Sévigny
- Centre de Recherche du CHU de Québec-Université Laval, CHUL, QC, Québec, Canada
- Département de Microbiologie-Infectiologie et d'Immunologie, Faculté de Médicine, Université Laval, QC, Québec, Canada
| | - J Miguel Cordeiro
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia-Center for Drug Discovery and Innovative Medicines (MedInUP), Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto (UP), R. Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.
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249
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Mishra A, Reynolds JP, Chen Y, Gourine AV, Rusakov DA, Attwell D. Astrocytes mediate neurovascular signaling to capillary pericytes but not to arterioles. Nat Neurosci 2016; 19:1619-1627. [PMID: 27775719 PMCID: PMC5131849 DOI: 10.1038/nn.4428] [Citation(s) in RCA: 365] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/20/2016] [Indexed: 12/11/2022]
Abstract
Active neurons increase their energy supply by dilating nearby arterioles and capillaries. This neurovascular coupling underlies blood oxygen level-dependent functional imaging signals, but its mechanism is controversial. Canonically, neurons release glutamate to activate metabotropic glutamate receptor 5 (mGluR5) on astrocytes, evoking Ca2+ release from internal stores, activating phospholipase A2 and generating vasodilatory arachidonic acid derivatives. However, adult astrocytes lack mGluR5, and knockout of the inositol 1,4,5-trisphosphate receptors that release Ca2+ from stores does not affect neurovascular coupling. We now show that buffering astrocyte Ca2+ inhibits neuronally evoked capillary dilation, that astrocyte [Ca2+]i is raised not by release from stores but by entry through ATP-gated channels, and that Ca2+ generates arachidonic acid via phospholipase D2 and diacylglycerol lipase rather than phospholipase A2. In contrast, dilation of arterioles depends on NMDA receptor activation and Ca2+-dependent NO generation by interneurons. These results reveal that different signaling cascades regulate cerebral blood flow at the capillary and arteriole levels.
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Affiliation(s)
- Anusha Mishra
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | | | - Yang Chen
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | - Alexander V Gourine
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | | | - David Attwell
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
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250
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Jennings A, Tyurikova O, Bard L, Zheng K, Semyanov A, Henneberger C, Rusakov DA. Dopamine elevates and lowers astroglial Ca 2+ through distinct pathways depending on local synaptic circuitry. Glia 2016; 65:447-459. [PMID: 27896839 PMCID: PMC5299530 DOI: 10.1002/glia.23103] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/10/2016] [Accepted: 11/11/2016] [Indexed: 12/18/2022]
Abstract
Whilst astrocytes in culture invariably respond to dopamine with cytosolic Ca2+ rises, the dopamine sensitivity of astroglia in situ and its physiological roles remain unknown. To minimize effects of experimental manipulations on astroglial physiology, here we monitored Ca2+ in cells connected via gap junctions to astrocytes loaded whole‐cell with cytosolic indicators in area CA1 of acute hippocampal slices. Aiming at high sensitivity of [Ca2+] measurements, we also employed life‐time imaging of the Ca2+ indicator Oregon Green BAPTA‐1. We found that dopamine triggered a dose‐dependent, bidirectional Ca2+ response in stratum radiatum astroglia, a jagged elevation accompanied and followed by below‐baseline decreases. The elevation depended on D1/D2 receptors and engaged intracellular Ca2+ storage and removal whereas the dopamine‐induced [Ca2+] decrease involved D2 receptors only and was sensitive to Ca2+ channel blockade. In contrast, the stratum lacunosum moleculare astroglia generated higher‐threshold dopamine‐induced Ca2+ responses which did not depend on dopamine receptors and were uncoupled from the prominent inhibitory action of dopamine on local perforant path synapses. Our findings thus suggest that a single neurotransmitter—dopamine—could either elevate or decrease astrocyte [Ca2+] depending on the receptors involved, that such actions are specific to the regional neural circuitry and that they may be causally uncoupled from dopamine actions on local synapses. The results also indicate that [Ca2+] elevations commonly detected in astroglia can represent the variety of distinct mechanisms acting on the microscopic scale. GLIA 2017;65:447–459
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Affiliation(s)
- Alistair Jennings
- UCL Institute of Neurology, University College London, London, United Kingdom
| | - Olga Tyurikova
- UCL Institute of Neurology, University College London, London, United Kingdom.,Institute of Neuroscience, University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
| | - Lucie Bard
- UCL Institute of Neurology, University College London, London, United Kingdom
| | - Kaiyu Zheng
- UCL Institute of Neurology, University College London, London, United Kingdom
| | - Alexey Semyanov
- Institute of Neuroscience, University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia.,RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Christian Henneberger
- UCL Institute of Neurology, University College London, London, United Kingdom.,Institute of Cellular Neurosciences, University of Bonn Medical School, Germany.,German Center of Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Dmitri A Rusakov
- UCL Institute of Neurology, University College London, London, United Kingdom.,Institute of Neuroscience, University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia
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