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Lei L, Wang YF, Chen CY, Wang YT, Zhang Y. Novel insight into astrocyte-mediated gliotransmission modulates the synaptic plasticity in major depressive disorder. Life Sci 2024; 355:122988. [PMID: 39153595 DOI: 10.1016/j.lfs.2024.122988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 07/23/2024] [Accepted: 08/13/2024] [Indexed: 08/19/2024]
Abstract
Major depressive disorder (MDD) is a form of glial cell-based synaptic dysfunction disease in which glial cells interact closely with neuronal synapses and perform synaptic information processing. Glial cells, particularly astrocytes, are active components of the brain and are responsible for synaptic activity through the release gliotransmitters. A reduced density of astrocytes and astrocyte dysfunction have both been identified the brains of patients with MDD. Furthermore, gliotransmission, i.e., active information transfer mediated by gliotransmitters between astrocytes and neurons, is thought to be involved in the pathogenesis of MDD. However, the mechanism by which astrocyte-mediated gliotransmission contributes to depression remains unknown. This review therefore summarizes the alterations in astrocytes in MDD, including astrocyte marker, connexin 43 (Cx43) expression, Cx43 gap junctions, and Cx43 hemichannels, and describes the regulatory mechanisms of astrocytes involved in synaptic plasticity. Additionally, we investigate the mechanisms acting of the glutamatergic, gamma-aminobutyric acidergic, and purinergic systems that modulate synaptic function and the antidepressant mechanisms of the related receptor antagonists. Further, we summarize the roles of glutamate, gamma-aminobutyric acid, d-serine, and adenosine triphosphate in depression, providing a basis for the identification of diagnostic and therapeutic targets for MDD.
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Affiliation(s)
- Lan Lei
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Yu-Fei Wang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Cong-Ya Chen
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Ya-Ting Wang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Yi Zhang
- Department of Anatomy, School of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China.
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2
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Puebla M, Muñoz MF, Lillo MA, Contreras JE, Figueroa XF. Control of astrocytic Ca 2+ signaling by nitric oxide-dependent S-nitrosylation of Ca 2+ homeostasis modulator 1 channels. Biol Res 2024; 57:19. [PMID: 38689353 PMCID: PMC11059852 DOI: 10.1186/s40659-024-00503-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 04/18/2024] [Indexed: 05/02/2024] Open
Abstract
BACKGROUND Astrocytes Ca2+ signaling play a central role in the modulation of neuronal function. Activation of metabotropic glutamate receptors (mGluR) by glutamate released during an increase in synaptic activity triggers coordinated Ca2+ signals in astrocytes. Importantly, astrocytes express the Ca2+-dependent nitric oxide (NO)-synthetizing enzymes eNOS and nNOS, which might contribute to the Ca2+ signals by triggering Ca2+ influx or ATP release through the activation of connexin 43 (Cx43) hemichannels, pannexin-1 (Panx-1) channels or Ca2+ homeostasis modulator 1 (CALHM1) channels. Hence, we aim to evaluate the participation of NO in the astrocytic Ca2+ signaling initiated by stimulation of mGluR in primary cultures of astrocytes from rat brain cortex. RESULTS Astrocytes were stimulated with glutamate or t-ACPD and NO-dependent changes in [Ca2+]i and ATP release were evaluated. In addition, the activity of Cx43 hemichannels, Panx-1 channels and CALHM1 channels was also analyzed. The expression of Cx43, Panx-1 and CALHM1 in astrocytes was confirmed by immunofluorescence analysis and both glutamate and t-ACPD induced NO-mediated activation of CALHM1 channels via direct S-nitrosylation, which was further confirmed by assessing CALHM1-mediated current using the two-electrode voltage clamp technique in Xenopus oocytes. Pharmacological blockade or siRNA-mediated inhibition of CALHM1 expression revealed that the opening of these channels provides a pathway for ATP release and the subsequent purinergic receptor-dependent activation of Cx43 hemichannels and Panx-1 channels, which further contributes to the astrocytic Ca2+ signaling. CONCLUSIONS Our findings demonstrate that activation of CALHM1 channels through NO-mediated S-nitrosylation in astrocytes in vitro is critical for the generation of glutamate-initiated astrocytic Ca2+ signaling.
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Affiliation(s)
- Mariela Puebla
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 8330025, Santiago, Chile
| | - Manuel F Muñoz
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 8330025, Santiago, Chile
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
| | - Mauricio A Lillo
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Jorge E Contreras
- Department of Physiology and Membrane Biology, University of California Davis, Davis, CA, USA
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Xavier F Figueroa
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, 8330025, Santiago, Chile.
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3
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Zhang Z, Luo Y, Ma Y, Zhou Y, Zhu D, Shen W, Liu J. Photocatalytic manipulation of Ca 2+ signaling for regulating cellular and animal behaviors via MOF-enabled H 2O 2 generation. SCIENCE ADVANCES 2024; 10:eadl0263. [PMID: 38640246 PMCID: PMC11029810 DOI: 10.1126/sciadv.adl0263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 03/18/2024] [Indexed: 04/21/2024]
Abstract
The in situ generation of H2O2 in cells in response to external stimulation has exceptional advantages in modulating intracellular Ca2+ dynamics, including high controllability and biological safety, but has been rarely explored. Here, we develop photocatalyst-based metal-organic frameworks (DCSA-MOFs) to modulate Ca2+ responses in cells, multicellular spheroids, and organs. By virtue of the efficient photocatalytic oxygen reduction to H2O2 without sacrificial agents, photoexcited DCSA-MOFs can rapidly trigger Ca2+ outflow from the endoplasmic reticulum with single-cell precision in a repeatable and controllable manner, enabling the propagation of intercellular Ca2+ waves (ICW) over long distances in two-dimensional and three-dimensional cell cultures. After photoexcitation, ICWs induced by DCSA-MOFs can activate neural activities in the optical tectum of tadpoles and thighs of spinal frogs, eliciting the corresponding motor behaviors. Our study offers a versatile optical nongenetic modulation technique that enables remote, repeatable, and controlled manipulation of cellular and animal behaviors.
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Affiliation(s)
- Zherui Zhang
- College of Material, Chemistry, and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, China
| | - Yuhao Luo
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Yuanhong Ma
- College of Material, Chemistry, and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, China
| | - Yaofeng Zhou
- Westlake University, Shilongshan Rd. Cloud Town, Xihu District, Hangzhou, Zhejiang, China
| | - Dingcheng Zhu
- College of Material, Chemistry, and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, China
| | - Wanhua Shen
- Zhejiang Key Laboratory of Organ Development and Regeneration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Junqiu Liu
- College of Material, Chemistry, and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, China
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4
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Tung A, Sperry MM, Clawson W, Pavuluri A, Bulatao S, Yue M, Flores RM, Pai VP, McMillen P, Kuchling F, Levin M. Embryos assist morphogenesis of others through calcium and ATP signaling mechanisms in collective teratogen resistance. Nat Commun 2024; 15:535. [PMID: 38233424 PMCID: PMC10794468 DOI: 10.1038/s41467-023-44522-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 12/17/2023] [Indexed: 01/19/2024] Open
Abstract
Information for organismal patterning can come from a variety of sources. We investigate the possibility that instructive influences for normal embryonic development are provided not only at the level of cells within the embryo, but also via interactions between embryos. To explore this, we challenge groups of embryos with disruptors of normal development while varying group size. Here, we show that Xenopus laevis embryos are much more sensitive to a diverse set of chemical and molecular-biological perturbations when allowed to develop alone or in small groups, than in large groups. Keeping per-embryo exposure constant, we find that increasing the number of exposed embryos in a cohort increases the rate of survival while incidence of defects decreases. This inter-embryo assistance effect is mediated by short-range diffusible signals and involves the P2 ATP receptor. Our data and computational model emphasize that morphogenesis is a collective phenomenon not only at the level of cells, but also of whole bodies, and that cohort size is a crucial variable in studies of ecotoxicology, teratogenesis, and developmental plasticity.
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Affiliation(s)
- Angela Tung
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Megan M Sperry
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Wesley Clawson
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Ananya Pavuluri
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Sydney Bulatao
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Michelle Yue
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Ramses Martinez Flores
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Vaibhav P Pai
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Patrick McMillen
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Franz Kuchling
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA, 02155, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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5
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Adermark L, Stomberg R, Söderpalm B, Ericson M. Astrocytic Regulation of Endocannabinoid-Dependent Synaptic Plasticity in the Dorsolateral Striatum. Int J Mol Sci 2024; 25:581. [PMID: 38203752 PMCID: PMC10779090 DOI: 10.3390/ijms25010581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 12/26/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Astrocytes are pivotal for synaptic transmission and may also play a role in the induction and expression of synaptic plasticity, including endocannabinoid-mediated long-term depression (eCB-LTD). In the dorsolateral striatum (DLS), eCB signaling plays a major role in balancing excitation and inhibition and promoting habitual learning. The aim of this study was to outline the role of astrocytes in regulating eCB signaling in the DLS. To this end, we employed electrophysiological slice recordings combined with metabolic, chemogenetic and pharmacological approaches in an attempt to selectively suppress astrocyte function. High-frequency stimulation induced eCB-mediated LTD (HFS-LTD) in brain slices from both male and female rats. The metabolic uncoupler fluorocitrate (FC) reduced the probability of transmitter release and depressed synaptic output in a manner that was independent on cannabinoid 1 receptor (CB1R) activation. Fluorocitrate did not affect the LTD induced by the CB1R agonist WIN55,212-2, but enhanced CB1R-dependent HFS-LTD. Reduced neurotransmission and facilitated HFS-LTD were also observed during chemogenetic manipulation using Gi-coupled DREADDs targeting glial fibrillary acidic protein (GFAP)-expressing cells, during the pharmacological inhibition of connexins using carbenoxolone disodium, or during astrocytic glutamate uptake using TFB-TBOA. While pretreatment with the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonopentanoic acid (APV) failed to prevent synaptic depression induced by FC, it blocked the facilitation of HFS-LTD. While the lack of tools to disentangle astrocytes from neurons is a major limitation of this study, our data collectively support a role for astrocytes in modulating basal neurotransmission and eCB-mediated synaptic plasticity.
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Affiliation(s)
- Louise Adermark
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Rosita Stomberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
| | - Bo Söderpalm
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
- Beroendekliniken, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden
| | - Mia Ericson
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, 40530 Gothenburg, Sweden; (R.S.); (B.S.); (M.E.)
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6
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Fritschi L, Lenk K. Parameter Inference for an Astrocyte Model using Machine Learning Approaches. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.16.540982. [PMID: 37292854 PMCID: PMC10245674 DOI: 10.1101/2023.05.16.540982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Astrocytes are the largest subset of glial cells and perform structural, metabolic, and regulatory functions. They are directly involved in the communication at neuronal synapses and the maintenance of brain homeostasis. Several disorders, such as Alzheimer's, epilepsy, and schizophrenia, have been associated with astrocyte dysfunction. Computational models on various spatial levels have been proposed to aid in the understanding and research of astrocytes. The difficulty of computational astrocyte models is to fastly and precisely infer parameters. Physics informed neural networks (PINNs) use the underlying physics to infer parameters and, if necessary, dynamics that can not be observed. We have applied PINNs to estimate parameters for a computational model of an astrocytic compartment. The addition of two techniques helped with the gradient pathologies of the PINNS, the dynamic weighting of various loss components and the addition of Transformers. To overcome the issue that the neural network only learned the time dependence but did not know about eventual changes of the input stimulation to the astrocyte model, we followed an adaptation of PINNs from control theory (PINCs). In the end, we were able to infer parameters from artificial, noisy data, with stable results for the computational astrocyte model.
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Affiliation(s)
| | - Kerstin Lenk
- Institute of Neural Engineering, Graz University of Technology, Graz, Austria
- BioTechMed, 8010 Graz, Austria
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7
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Giantomasi L, Ribeiro JF, Barca-Mayo O, Malerba M, Miele E, De Pietri Tonelli D, Berdondini L. Astrocytes actively support long-range molecular clock synchronization of segregated neuronal populations. Sci Rep 2023; 13:4815. [PMID: 36964220 PMCID: PMC10038999 DOI: 10.1038/s41598-023-31966-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 03/20/2023] [Indexed: 03/26/2023] Open
Abstract
In mammals, the suprachiasmatic nucleus of the hypothalamus is the master circadian pacemaker that synchronizes the clocks in the central nervous system and periphery, thus orchestrating rhythms throughout the body. However, little is known about how so many cellular clocks within and across brain circuits can be effectively synchronized. In this work, we investigated the implication of two possible pathways: (i) astrocytes-mediated synchronization and (ii) neuronal paracrine factors-mediated synchronization. By taking advantage of a lab-on-a-chip microfluidic device developed in our laboratory, here we report that both pathways are involved. We found the paracrine factors-mediated synchronization of molecular clocks is diffusion-limited and, in our device, effective only in case of a short distance between neuronal populations. Interestingly, interconnecting astrocytes define an active signaling channel that can synchronize molecular clocks of neuronal populations also at longer distances. At mechanism level, we found that astrocytes-mediated synchronization involves both GABA and glutamate, while neuronal paracrine factors-mediated synchronization occurs through GABA signaling. These findings identify a previously unknown role of astrocytes as active cells that might distribute long-range signals to synchronize the brain clocks, thus further strengthening the importance of reciprocal interactions between glial and neuronal cells in the context of circadian circuitry.
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Affiliation(s)
- Lidia Giantomasi
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
| | - João F Ribeiro
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
| | - Olga Barca-Mayo
- Neurobiology of miRNA, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- Circadian and Glial Biology Lab, Physiology Department, Molecular Medicine, and Chronic Diseases Research Centre (CiMUS), University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Mario Malerba
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris-Saclay, 91120, Palaiseau, France
| | - Ermanno Miele
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy
- NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, UK
| | | | - Luca Berdondini
- Microtechnology for Neuroelectronics, Fondazione Istituto Italiano Di Tecnologia (IIT), 16163, Genova, Italy.
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8
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Tsytsarev V. Methodological aspects of studying the mechanisms of consciousness. Behav Brain Res 2022; 419:113684. [PMID: 34838578 DOI: 10.1016/j.bbr.2021.113684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 11/21/2021] [Accepted: 11/22/2021] [Indexed: 11/24/2022]
Abstract
There are at least two approaches to the definition of consciousness. In the first case, certain aspects of consciousness, called qualia, are considered inaccessible for research from a third person and can only be described through subjective experience. This approach is inextricably linked with the so-called "hard problem of consciousness", that is, the question of why consciousness has qualia or how any physical changes in the environment can generate subjective experience. With this approach, some aspects of consciousness, by definition, cannot be explained on the basis of external observations and, therefore, are outside the scope of scientific research. In the second case, a priori constraints do not constrain the field of scientific investigation, and the best explanation of the experience in the first person is included as a possible subject of empirical research. Historically, in the study of cause-and-effect relationships in biology, it was customary to distinguish between proximate causation and ultimate causation existing in biological systems. Immediate causes are based on the immediate influencing factors [1]. Proximate causation has evolutionary explanations. When studying biological systems themselves, such an approach is undoubtedly justified, but it often seems insufficient when studying the interaction of consciousness and the brain [2,3]. Current scientific communities proceed from the assumption that the physical substrate for the generation of consciousness is a neural network that unites various types of neurons located in various brain structures. Many neuroscientists attach a key role in this process to the cortical and thalamocortical neural networks. This question is directly related to experimental and clinical research in the field of disorder of consciousness. Progress in this area of medicine depends on advances in neuroscience in this area and is also a powerful source of empirical information. In this area of consciousness research, a large amount of experimental data has been accumulated, and in this review an attempt was made to generalize and systematize.
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9
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Panattoni G, Amoriello R, Memo C, Thalhammer A, Ballerini C, Ballerini L. Diverse inflammatory threats modulate astrocytes Ca 2+ signaling via connexin43 hemichannels in organotypic spinal slices. Mol Brain 2021; 14:159. [PMID: 34696792 PMCID: PMC8547100 DOI: 10.1186/s13041-021-00868-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/15/2021] [Indexed: 02/07/2023] Open
Abstract
Neuroinflammation is an escalation factor shared by a vast range of central nervous system (CNS) pathologies, from neurodegenerative diseases to neuropsychiatric disorders. CNS immune status emerges by the integration of the responses of resident and not resident cells, leading to alterations in neural circuits functions. To explore spinal cord astrocyte reactivity to inflammatory threats we focused our study on the effects of local inflammation in a controlled micro-environment, the organotypic spinal slices, developed from the spinal cord of mouse embryos. These organ cultures represent a complex in vitro model where sensory-motor cytoarchitecture, synaptic properties and spinal cord resident cells, are retained in a 3D fashion and we recently exploit these cultures to model two diverse immune conditions in the CNS, involving different inflammatory networks and products. Here, we specifically focus on the tuning of calcium signaling in astrocytes by these diverse types of inflammation and we investigate the mechanisms which modulate intracellular calcium release and its spreading among astrocytes in the inflamed environment. Organotypic spinal cord slices are cultured for two or three weeks in vitro (WIV) and exposed for 6 h to a cocktail of cytokines (CKs), composed by tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1 β) and granulocyte macrophage-colony stimulating factor (GM-CSF), or to lipopolysaccharide (LPS). By live calcium imaging of the ventral horn, we document an increase in active astrocytes and in the occurrence of spontaneous calcium oscillations displayed by these cells when exposed to each inflammatory threat. Through several pharmacological treatments, we demonstrate that intracellular calcium sources and the activation of connexin 43 (Cx43) hemichannels have a pivotal role in increasing calcium intercellular communication in both CKs and LPS conditions, while the Cx43 gap junction communication is apparently reduced by the inflammatory treatments.
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Affiliation(s)
- Giulia Panattoni
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Roberta Amoriello
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.,Dipartimento di Medicina Sperimentale e Clinica, University of Florence, 50139, Florence, Italy
| | - Christian Memo
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Agnes Thalhammer
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Clara Ballerini
- Dipartimento di Medicina Sperimentale e Clinica, University of Florence, 50139, Florence, Italy.
| | - Laura Ballerini
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.
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10
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Rao SB, Skauli N, Jovanovic N, Katoozi S, Frigeri A, Froehner SC, Adams ME, Ottersen OP, Amiry-Moghaddam M. Orchestrating aquaporin-4 and connexin-43 expression in brain: Differential roles of α1- and β1-syntrophin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183616. [PMID: 33872576 DOI: 10.1016/j.bbamem.2021.183616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/22/2021] [Accepted: 03/25/2021] [Indexed: 01/09/2023]
Abstract
Aquaporin-4 (AQP4) water channels and gap junction proteins (connexins) are two classes of astrocytic membrane proteins critically involved in brain water and ion homeostasis. AQP4 channels are anchored by α1-syntrophin to the perivascular astrocytic endfoot membrane domains where they control water flux at the blood-brain interface while connexins cluster at the lateral aspects of the astrocytic endfeet forming gap junctions that allow water and ions to dissipate through the astrocyte syncytium. Recent studies have pointed to an interdependence between astrocytic AQP4 and astrocytic gap junctions but the underlying mechanism remains to be explored. Here we use a novel transgenic mouse line to unravel whether β1-syntrophin (coexpressed with α1-syntrophin in astrocytic plasma membranes) is implicated in the expression of AQP4 isoforms and formation of gap junctions in brain. Our results show that while the effect of β1-syntrophin deletion is rather limited, double knockout of α1- and β1-syntrophin causes a downregulation of the novel AQP4 isoform AQP4ex and an increase in the number of astrocytic gap junctions. The present study highlight the importance of syntrophins in orchestrating specialized functional domains of brain astrocytes.
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Affiliation(s)
- Shreyas B Rao
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway.
| | - Nadia Skauli
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway.
| | - Nenad Jovanovic
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway
| | - Shirin Katoozi
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway
| | - Antonio Frigeri
- School of Medicine, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari Aldo Moro, Bari, Italy.
| | - Stanley C Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA.
| | - Marvin E Adams
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA.
| | - Ole Petter Ottersen
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway.
| | - Mahmood Amiry-Moghaddam
- Laboratory of Molecular Neuroscience, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Post box 1105, Blindern, 0317 Oslo, Norway.
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11
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Cell specific quantitative iron mapping on brain slices by immuno-µPIXE in healthy elderly and Parkinson's disease. Acta Neuropathol Commun 2021; 9:47. [PMID: 33752749 PMCID: PMC7986300 DOI: 10.1186/s40478-021-01145-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/28/2021] [Indexed: 12/17/2022] Open
Abstract
Iron is essential for neurons and glial cells, playing key roles in neurotransmitter synthesis, energy production and myelination. In contrast, high concentrations of free iron can be detrimental and contribute to neurodegeneration, through promotion of oxidative stress. Particularly in Parkinson’s disease (PD) changes in iron concentrations in the substantia nigra (SN) was suggested to play a key role in degeneration of dopaminergic neurons in nigrosome 1. However, the cellular iron pathways and the mechanisms of the pathogenic role of iron in PD are not well understood, mainly due to the lack of quantitative analytical techniques for iron quantification with subcellular resolution. Here, we quantified cellular iron concentrations and subcellular iron distributions in dopaminergic neurons and different types of glial cells in the SN both in brains of PD patients and in non-neurodegenerative control brains (Co). To this end, we combined spatially resolved quantitative element mapping using micro particle induced X-ray emission (µPIXE) with nickel-enhanced immunocytochemical detection of cell type-specific antigens allowing to allocate element-related signals to specific cell types. Distinct patterns of iron accumulation were observed across different cell populations. In the control (Co) SNc, oligodendroglial and astroglial cells hold the highest cellular iron concentration whereas in PD, the iron concentration was increased in most cell types in the substantia nigra except for astroglial cells and ferritin-positive oligodendroglial cells. While iron levels in astroglial cells remain unchanged, ferritin in oligodendroglial cells seems to be depleted by almost half in PD. The highest cellular iron levels in neurons were located in the cytoplasm, which might increase the source of non-chelated Fe3+, implicating a critical increase in the labile iron pool. Indeed, neuromelanin is characterised by a significantly higher loading of iron including most probable the occupancy of low-affinity iron binding sites. Quantitative trace element analysis is essential to characterise iron in oxidative processes in PD. The quantification of iron provides deeper insights into changes of cellular iron levels in PD and may contribute to the research in iron-chelating disease-modifying drugs.
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12
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Stephan J, Eitelmann S, Zhou M. Approaches to Study Gap Junctional Coupling. Front Cell Neurosci 2021; 15:640406. [PMID: 33776652 PMCID: PMC7987795 DOI: 10.3389/fncel.2021.640406] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Astrocytes and oligodendrocytes are main players in the brain to ensure ion and neurotransmitter homeostasis, metabolic supply, and fast action potential propagation in axons. These functions are fostered by the formation of large syncytia in which mainly astrocytes and oligodendrocytes are directly coupled. Panglial networks constitute on connexin-based gap junctions in the membranes of neighboring cells that allow the passage of ions, metabolites, and currents. However, these networks are not uniform but exhibit a brain region-dependent heterogeneous connectivity influencing electrical communication and intercellular ion spread. Here, we describe different approaches to analyze gap junctional communication in acute tissue slices that can be implemented easily in most electrophysiology and imaging laboratories. These approaches include paired recordings, determination of syncytial isopotentiality, tracer coupling followed by analysis of network topography, and wide field imaging of ion sensitive dyes. These approaches are capable to reveal cellular heterogeneity causing electrical isolation of functional circuits, reduced ion-transfer between different cell types, and anisotropy of tracer coupling. With a selective or combinatory use of these methods, the results will shed light on cellular properties of glial cells and their contribution to neuronal function.
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Affiliation(s)
- Jonathan Stephan
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sara Eitelmann
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Min Zhou
- Department of Neuroscience, Wexner Medical Center, Ohio State University, Columbus, OH, United States
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13
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Richard C, Ruiz A, Cavagna S, Bigotte M, Vukusic S, Masaki K, Suenaga T, Kira JI, Giraudon P, Marignier R. Connexins in neuromyelitis optica: a link between astrocytopathy and demyelination. Brain 2021; 143:2721-2732. [PMID: 32889550 DOI: 10.1093/brain/awaa227] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/01/2020] [Accepted: 05/06/2020] [Indexed: 01/26/2023] Open
Abstract
Neuromyelitis optica, a rare neuroinflammatory demyelinating disease of the CNS, is characterized by the presence of specific pathogenic autoantibodies directed against the astrocytic water channel aquaporin 4 (AQP4) and is now considered as an astrocytopathy associated either with complement-dependent astrocyte death or with astrocyte dysfunction. However, the link between astrocyte dysfunction and demyelination remains unclear. We propose glial intercellular communication, supported by connexin hemichannels and gap junctions, to be involved in demyelination process in neuromyelitis optica. Using mature myelinated cultures, we demonstrate that a treatment of 1 h to 48 h with immunoglobulins purified from patients with neuromyelitis optica (NMO-IgG) is responsible for a complement independent demyelination, compared to healthy donors' immunoglobulins (P < 0.001). In parallel, patients' immunoglobulins induce an alteration of connexin expression characterized by a rapid loss of astrocytic connexins at the membrane followed by an increased size of gap junction plaques (+60%; P < 0.01). This was co-observed with connexin dysfunction with gap junction disruption (-57%; P < 0.001) and increased hemichannel opening (+17%; P < 0.001), associated with glutamate release. Blocking connexin 43 hemichannels with a specific peptide was able to prevent demyelination in co-treatment with patients compared to healthy donors' immunoglobulins. By contrast, the blockade of connexin 43 gap junctions with another peptide was detrimental for myelin (myelin density -48%; P < 0.001). Overall, our results suggest that dysregulation of connexins would play a pathogenetic role in neuromyelitis optica. The further identification of mechanisms leading to connexin dysfunction and soluble factors implicated, would provide interesting therapeutic strategies for demyelinating disorders.
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Affiliation(s)
- Chloé Richard
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Anne Ruiz
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Sylvie Cavagna
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Maxime Bigotte
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Sandra Vukusic
- Service de neurologie, sclérose en plaques, pathologies de la myéline et neuro-inflammation, Hôpital Neurologique Pierre Wertheimer Hospices Civils de Lyon, Lyon, France.,Centre de référence des maladies inflammatoires rares du cerveau et de la moelle, Lyon, France
| | - Katsuhisa Masaki
- Department of Neurology, Neurological institute, Graduate School of Medical Sciences, Kyushu University
| | | | - Jun-Ichi Kira
- Department of Neurology, Neurological institute, Graduate School of Medical Sciences, Kyushu University
| | - Pascale Giraudon
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Romain Marignier
- INSERM U1028, CNRS UMR 5292, Lyon1 University, Center for Research in Neuroscience of Lyon, Lyon, France.,Service de neurologie, sclérose en plaques, pathologies de la myéline et neuro-inflammation, Hôpital Neurologique Pierre Wertheimer Hospices Civils de Lyon, Lyon, France.,Centre de référence des maladies inflammatoires rares du cerveau et de la moelle, Lyon, France
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14
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Charvériat M, Mouthon F, Rein W, Verkhratsky A. Connexins as therapeutic targets in neurological and neuropsychiatric disorders. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166098. [PMID: 33545299 DOI: 10.1016/j.bbadis.2021.166098] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/06/2021] [Accepted: 01/19/2021] [Indexed: 12/16/2022]
Abstract
Astrocytes represent the reticular part of the central nervous system; gap junctions formed by connexins Cx43, Cx30- and Cx26 provide for homocellular astrocyte-astrocyte coupling, whereas connexins Cx30, Cx32, Cx43, and Cx47 connect astrocytes and oligodendrocytes. Astroglial networks are anatomically and functionally segregated being homologous to neuronal ensembles. Connexons, gap junctions and hemichannels (unpaired connexons) are affected in various neuropathologies from neuropsychiatric to neurodegenerative diseases. Manipulation of astrocytic connexins modulates the size and outreach of astroglial syncytia thus affecting astroglial homeostatic support. Modulation of astrocytic connexin significantly modifies pharmacological profile of many CNS drugs, which represents an innovative therapeutic approach for CNS disorders; this approach is now actively tested in pre-clinical and clinical studies. Wide combination of connexin modulators with CNS drugs open new promising perspectives for fundamental studies and therapeutic strategies.
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Affiliation(s)
| | | | | | - A Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
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15
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Zhou A, Liu X, Zhang S, Huo B. Effects of store-operated and receptor-operated calcium channels on synchronization of calcium oscillations in astrocytes. Biosystems 2020; 198:104233. [PMID: 32858094 DOI: 10.1016/j.biosystems.2020.104233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/04/2020] [Accepted: 08/20/2020] [Indexed: 10/23/2022]
Abstract
Intercellular calcium signaling allows cells to communicate with each other and to interact with adjacent cells. Gap junction is the most common and important way for cellular communication. Recently, mathematical models have been widely used to gain a precise and quantitative understanding of the dynamics of intracellular calcium ions (Ca2+). In this paper, we establish a mathematical model considering the gap junction permeable to Ca2+ and to IP3 for describing the calcium oscillations in coupled astrocytes. Store-operated calcium entry (SOCE) is viewed as the main process which controls the non-excitable cells, hence, we focus on the effect of store-operated calcium channel (SOCC) and receptor-operated calcium channel (ROCC) on the intercellular synchronization, respectively. By employing bifurcation analysis on this model, the dynamic behaviors of the coupled system with different physiological state cells is obtained with changes in the maximum capacity of the SOCC and the ROCC. The synchronization boundaries for different conditions are gained in the two parameters space of the channel parameters and the coupling strength. The results suggest that the variation of the maximum flow for different calcium channels determines the stable oscillations of the coupled system, as well as for the frequency and amplitude of oscillations. The SOCC has an expected effect on the change of the oscillatory interval while the ROCC demonstrated the influence on the amplitude modulation. Furthermore, the coupling strength and channel parameters could induce 1:1 locking of intercellular Ca2+ oscillations and the synchronization region like Arnol'd tongue is found.
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Affiliation(s)
- Anqi Zhou
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China
| | - Xijun Liu
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China
| | - Suxia Zhang
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China.
| | - Bing Huo
- College of Mechanical Engineering, Tianjin University of Science & Technology, Tianjin, 300222, PR China
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16
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Dere D, Zlomuzica A, Dere E. Channels to consciousness: a possible role of gap junctions in consciousness. Rev Neurosci 2020; 32:/j/revneuro.ahead-of-print/revneuro-2020-0012/revneuro-2020-0012.xml. [PMID: 32853172 DOI: 10.1515/revneuro-2020-0012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/26/2020] [Indexed: 12/20/2022]
Abstract
The neurophysiological basis of consciousness is still unknown and one of the most challenging questions in the field of neuroscience and related disciplines. We propose that consciousness is characterized by the maintenance of mental representations of internal and external stimuli for the execution of cognitive operations. Consciousness cannot exist without working memory, and it is likely that consciousness and working memory share the same neural substrates. Here, we present a novel psychological and neurophysiological framework that explains the role of consciousness for cognition, adaptive behavior, and everyday life. A hypothetical architecture of consciousness is presented that is organized as a system of operation and storage units named platforms that are controlled by a consciousness center (central executive/online platform). Platforms maintain mental representations or contents, are entrusted with different executive functions, and operate at different levels of consciousness. The model includes conscious-mode central executive/online and mental time travel platforms and semiconscious steady-state and preconscious standby platforms. Mental representations or contents are represented by neural circuits and their support cells (astrocytes, oligodendrocytes, etc.) and become conscious when neural circuits reverberate, that is, fire sequentially and continuously with relative synchronicity. Reverberatory activity in neural circuits may be initiated and maintained by pacemaker cells/neural circuit pulsars, enhanced electronic coupling via gap junctions, and unapposed hemichannel opening. The central executive/online platform controls which mental representations or contents should become conscious by recruiting pacemaker cells/neural network pulsars, the opening of hemichannels, and promoting enhanced neural circuit coupling via gap junctions.
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Affiliation(s)
- Dorothea Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
| | - Armin Zlomuzica
- Faculty of Psychology, Behavioral and Clinical Neuroscience, University of Bochum, Massenbergstraße 9-13, D-44787 Bochum, Germany
| | - Ekrem Dere
- Département UMR 8256 Adaptation Biologique et Vieillissement, Sorbonne Université, Institut de Biologie Paris-Seine, (IBPS), UFR des Sciences de la Vie, Campus Pierre et Marie Curie, Bâtiment B, 9 quai Saint Bernard, F-75005 Paris Cedex, France
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17
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Piette C, Cui Y, Gervasi N, Venance L. Lights on Endocannabinoid-Mediated Synaptic Potentiation. Front Mol Neurosci 2020; 13:132. [PMID: 32848597 PMCID: PMC7399367 DOI: 10.3389/fnmol.2020.00132] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/26/2020] [Indexed: 12/15/2022] Open
Abstract
The endocannabinoid (eCB) system is a lipid-based neurotransmitter complex that plays crucial roles in the neural control of learning and memory. The current model of eCB-mediated retrograde signaling is that eCBs released from postsynaptic elements travel retrogradely to presynaptic axon terminals, where they activate cannabinoid type-1 receptors (CB1Rs) and ultimately decrease neurotransmitter release on a short- or long-term scale. An increasing body of evidence has enlarged this view and shows that eCBs, besides depressing synaptic transmission, are also able to increase neurotransmitter release at multiple synapses of the brain. This indicates that eCBs act as bidirectional regulators of synaptic transmission and plasticity. Recently, studies unveiled links between the expression of eCB-mediated long-term potentiation (eCB-LTP) and learning, and between its dysregulation and several pathologies. In this review article, we first distinguish the various forms of eCB-LTP based on their mechanisms, resulting from homosynaptically or heterosynaptically-mediated processes. Next, we consider the neuromodulation of eCB-LTP, its behavioral impact on learning and memory, and finally, eCB-LTP disruptions in various pathologies and its potential as a therapeutic target in disorders such as stress coping, addiction, Alzheimer’s and Parkinson’s disease, and pain. Cannabis is gaining popularity as a recreational substance as well as a medicine, and multiple eCB-based drugs are under development. In this context, it is critical to understand eCB-mediated signaling in its multi-faceted complexity. Indeed, the bidirectional nature of eCB-based neuromodulation may offer an important key to interpret the functions of the eCB system and how it is impacted by cannabis and other drugs.
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Affiliation(s)
- Charlotte Piette
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
| | - Yihui Cui
- Department of Neurobiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Nicolas Gervasi
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, College de France, INSERM U1050, CNRS UMR7241, Labex Memolife, Paris, France
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18
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Tabernero A, Koulakoff A, Roux L, Venance L, Leybaert L, Sáez JC, Naus CC. Christian Giaume (November 1951–July 2019). Glia 2020. [DOI: 10.1002/glia.23836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Arantxa Tabernero
- Department of Biochemistry and Molecular Biology. Institute of Neurosciences Castilla y León (INCYL), University of Salamanc Salamanca Spain
| | - Annette Koulakoff
- Center for Interdisciplinary Research in Biology, Collége de France, CNRSUMR7241/INSERM U1050, MemoLife Labex, 75005 Paris France
| | - Lisa Roux
- Interdisciplinary Institute for Neuroscience, UMR5297, Centre National de la Recherche Scientifique, University of Bordeaux Bordeaux France
| | - Laurent Venance
- Center for Interdisciplinary Research in Biology, Collége de France, CNRSUMR7241/INSERM U1050, MemoLife Labex, 75005 Paris France
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences, Physiology GroupUniversity of Ghent Ghent Belgium
| | - Juan C. Sáez
- Departamento de Ciencias FisiológicasPontificia Universidad Católica de Chile, Instituto de Neurociencias, Universidad de Valparaíso Chile
| | - Christian C. Naus
- Department of Cellular and Physiological SciencesLife Sciences Institute, The University of British Columbia Vancouver British Columbia Canada
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19
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Rigby MJ, Gomez TM, Puglielli L. Glial Cell-Axonal Growth Cone Interactions in Neurodevelopment and Regeneration. Front Neurosci 2020; 14:203. [PMID: 32210757 PMCID: PMC7076157 DOI: 10.3389/fnins.2020.00203] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 02/24/2020] [Indexed: 12/19/2022] Open
Abstract
The developing nervous system is a complex yet organized system of neurons, glial support cells, and extracellular matrix that arranges into an elegant, highly structured network. The extracellular and intracellular events that guide axons to their target locations have been well characterized in many regions of the developing nervous system. However, despite extensive work, we have a poor understanding of how axonal growth cones interact with surrounding glial cells to regulate network assembly. Glia-to-growth cone communication is either direct through cellular contacts or indirect through modulation of the local microenvironment via the secretion of factors or signaling molecules. Microglia, oligodendrocytes, astrocytes, Schwann cells, neural progenitor cells, and olfactory ensheathing cells have all been demonstrated to directly impact axon growth and guidance. Expanding our understanding of how different glial cell types directly interact with growing axons throughout neurodevelopment will inform basic and clinical neuroscientists. For example, identifying the key cellular players beyond the axonal growth cone itself may provide translational clues to develop therapeutic interventions to modulate neuron growth during development or regeneration following injury. This review will provide an overview of the current knowledge about glial involvement in development of the nervous system, specifically focusing on how glia directly interact with growing and maturing axons to influence neuronal connectivity. This focus will be applied to the clinically-relevant field of regeneration following spinal cord injury, highlighting how a better understanding of the roles of glia in neurodevelopment can inform strategies to improve axon regeneration after injury.
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Affiliation(s)
- Michael J Rigby
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States.,Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States.,Waisman Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Timothy M Gomez
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States.,Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, United States
| | - Luigi Puglielli
- Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States.,Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States.,Waisman Center, University of Wisconsin-Madison, Madison, WI, United States.,Geriatric Research Education Clinical Center, Veterans Affairs Medical Center, Madison, WI, United States
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20
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Cordaro M, Cuzzocrea S, Crupi R. An Update of Palmitoylethanolamide and Luteolin Effects in Preclinical and Clinical Studies of Neuroinflammatory Events. Antioxidants (Basel) 2020; 9:antiox9030216. [PMID: 32150935 PMCID: PMC7139331 DOI: 10.3390/antiox9030216] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/25/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
The inflammation process represents of a dynamic series of phenomena that manifest themselves with an intense vascular reaction. Neuroinflammation is a reply from the central nervous system (CNS) and the peripheral nervous system (PNS) to a changed homeostasis. There are two cell systems that mediate this process: the glia of the CNS and the lymphocites, monocytes, and macrophages of the hematopoietic system. In both the peripheral and central nervous systems, neuroinflammation plays an important role in the pathogenesis of neurodegenerative diseases, such as Parkinson’s and Alzheimer’s diseases, and in neuropsychiatric illnesses, such as depression and autism spectrum disorders. The resolution of neuroinflammation is a process that allows for inflamed tissues to return to homeostasis. In this process the important players are represented by lipid mediators. Among the naturally occurring lipid signaling molecules, a prominent role is played by the N-acylethanolamines, namely N-arachidonoylethanolamine and its congener N-palmitoylethanolamine, which is also named palmitoylethanolamide or PEA. PEA possesses a powerful neuroprotective and anti-inflammatory power but has no antioxidant effects per se. For this reason, its co-ultramicronization with the flavonoid luteolin is more efficacious than either molecule alone. Inhibiting or modulating the enzymatic breakdown of PEA represents a complementary therapeutic approach to treating neuroinflammation. The aim of this review is to discuss the role of ultramicronized PEA and co-ultramicronized PEA with luteolin in several neurological diseases using preclinical and clinical approaches.
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Affiliation(s)
- Marika Cordaro
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Via Consolare Valeria 1, 98100 Messina, Italy;
| | - Salvatore Cuzzocrea
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Via F. Stagno D’Alcontres 31, 98166 Messina, Italy;
- Department of Pharmacology and Physiology, Saint Louis University, St. Louis, MO 63103, USA
- Correspondence: ; Tel.: +390-906-765-208
| | - Rosalia Crupi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Via F. Stagno D’Alcontres 31, 98166 Messina, Italy;
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21
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Beiersdorfer A, Scheller A, Kirchhoff F, Lohr C. Panglial gap junctions between astrocytes and olfactory ensheathing cells mediate transmission of Ca 2+ transients and neurovascular coupling. Glia 2019; 67:1385-1400. [PMID: 30883940 DOI: 10.1002/glia.23613] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 12/13/2022]
Abstract
Astrocytes are arranged in highly organized gap junction-coupled networks, communicating via the propagation of Ca2+ waves. Astrocytes are gap junction-coupled not only to neighboring astrocytes, but also to oligodendrocytes, forming so-called panglial syncytia. It is not known, however, whether glial cells in panglial syncytia transmit information using Ca2+ signaling. We used confocal Ca2+ imaging to study intercellular communication between astrocytes and olfactory ensheathing glial cells (OECs) in in-toto preparations of the mouse olfactory bulb. Our results demonstrate that Ca2+ transients in juxtaglomerular astrocytes, evoked by local photolysis of "caged" ATP and "caged" tACPD, led to subsequent Ca2+ responses in OECs. This transmission of Ca2+ responses from astrocytes to OECs persisted in the presence of neuronal inhibition, but was absent when gap junctional coupling was suppressed with carbenoxolone. When Ca2+ transients were directly evoked in OECs by puff application of DHPG, they resulted in delayed Ca2+ responses in juxtaglomerular astrocytes, indicating that panglial transmission of Ca2+ signals occurred in a bidirectional manner. In addition, panglial transmission of Ca2+ signals from astrocytes to OECs resulted in vasoconstriction of OEC-associated blood vessels in the olfactory nerve layer. Our results demonstrate functional transmission of Ca2+ signals between different classes of glial cells within gap junction-coupled panglial networks and the resulting regulation of blood vessel diameter in the olfactory bulb.
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Affiliation(s)
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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22
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23
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Xin W, Schuebel KE, Jair KW, Cimbro R, De Biase LM, Goldman D, Bonci A. Ventral midbrain astrocytes display unique physiological features and sensitivity to dopamine D2 receptor signaling. Neuropsychopharmacology 2019; 44:344-355. [PMID: 30054584 PMCID: PMC6300565 DOI: 10.1038/s41386-018-0151-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 05/16/2018] [Accepted: 07/01/2018] [Indexed: 12/26/2022]
Abstract
Astrocytes are ubiquitous CNS cells that support tissue homeostasis through ion buffering, neurotransmitter recycling, and regulation of CNS vasculature. Yet, despite the essential functional roles they fill, very little is known about the physiology of astrocytes in the ventral midbrain, a region that houses dopamine-releasing neurons and is critical for reward learning and motivated behaviors. Here, using a combination of whole-transcriptome sequencing, histology, slice electrophysiology, and calcium imaging, we performed the first functional and molecular profiling of ventral midbrain astrocytes and observed numerous differences between these cells and their telencephalic counterparts, both in their gene expression profile and in their physiological properties. Ventral midbrain astrocytes have very low membrane resistance and inward-rectifying potassium channel-mediated current, and are extensively coupled to surrounding oligodendrocytes through gap junctions. They exhibit calcium responses to glutamate but are relatively insensitive to norepinephrine. In addition, their calcium activity can be dynamically modulated by dopamine D2 receptor signaling. Taken together, these data indicate that ventral midbrain astrocytes are physiologically distinct from astrocytes in cortex and hippocampus. This work provides new insights into the extent of functional astrocyte heterogeneity within the adult brain and establishes the foundation for examining the impact of regional astrocyte differences on dopamine neuron function and susceptibility to degeneration.
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Affiliation(s)
- Wendy Xin
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA. .,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
| | - Kornel E. Schuebel
- 0000 0001 2297 5165grid.94365.3dLaboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852 USA
| | - Kam-wing Jair
- 0000 0001 2297 5165grid.94365.3dLaboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852 USA
| | - Raffaello Cimbro
- 0000 0001 2171 9311grid.21107.35Department of Rheumatology, Johns Hopkins University School of Medicine, Baltimore, MD 21224 USA
| | - Lindsay M. De Biase
- 0000 0001 2297 5165grid.94365.3dIntramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224 USA
| | - David Goldman
- 0000 0001 2297 5165grid.94365.3dLaboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852 USA
| | - Antonello Bonci
- Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, 21224, USA. .,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. .,Department of Neuroscience, Georgetown University Medical Center, School of Medicine, Washington, DC, USA. .,Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
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24
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Manninen T, Havela R, Linne ML. Computational Models for Calcium-Mediated Astrocyte Functions. Front Comput Neurosci 2018; 12:14. [PMID: 29670517 PMCID: PMC5893839 DOI: 10.3389/fncom.2018.00014] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 02/28/2018] [Indexed: 12/16/2022] Open
Abstract
The computational neuroscience field has heavily concentrated on the modeling of neuronal functions, largely ignoring other brain cells, including one type of glial cell, the astrocytes. Despite the short history of modeling astrocytic functions, we were delighted about the hundreds of models developed so far to study the role of astrocytes, most often in calcium dynamics, synchronization, information transfer, and plasticity in vitro, but also in vascular events, hyperexcitability, and homeostasis. Our goal here is to present the state-of-the-art in computational modeling of astrocytes in order to facilitate better understanding of the functions and dynamics of astrocytes in the brain. Due to the large number of models, we concentrated on a hundred models that include biophysical descriptions for calcium signaling and dynamics in astrocytes. We categorized the models into four groups: single astrocyte models, astrocyte network models, neuron-astrocyte synapse models, and neuron-astrocyte network models to ease their use in future modeling projects. We characterized the models based on which earlier models were used for building the models and which type of biological entities were described in the astrocyte models. Features of the models were compared and contrasted so that similarities and differences were more readily apparent. We discovered that most of the models were basically generated from a small set of previously published models with small variations. However, neither citations to all the previous models with similar core structure nor explanations of what was built on top of the previous models were provided, which made it possible, in some cases, to have the same models published several times without an explicit intention to make new predictions about the roles of astrocytes in brain functions. Furthermore, only a few of the models are available online which makes it difficult to reproduce the simulation results and further develop the models. Thus, we would like to emphasize that only via reproducible research are we able to build better computational models for astrocytes, which truly advance science. Our study is the first to characterize in detail the biophysical and biochemical mechanisms that have been modeled for astrocytes.
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Affiliation(s)
- Tiina Manninen
- Computational Neuroscience Group, BioMediTech Institute and Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, Tampere, Finland
| | | | - Marja-Leena Linne
- Computational Neuroscience Group, BioMediTech Institute and Faculty of Biomedical Sciences and Engineering, Tampere University of Technology, Tampere, Finland
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25
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Ren Q, Wang ZZ, Chu SF, Xia CY, Chen NH. Gap junction channels as potential targets for the treatment of major depressive disorder. Psychopharmacology (Berl) 2018; 235:1-12. [PMID: 29178009 DOI: 10.1007/s00213-017-4782-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 11/05/2017] [Indexed: 01/08/2023]
Abstract
BACKGROUND Major depressive disorder (MDD) remains a major public health problem worldwide. The association between MDD and the dysfunction of gap junction channels (GJCs) in glial cells, especially astrocytes, is still controversial. OBJECTIVE This review provides an overview of the role of astrocyte GJCs in LMDD. RESULTS Exposure to chronic unpredictable stress caused a reduction in connexin expression in the rat prefrontal cortex, a result that is consistent with clinical findings reported in postmortem studies of brains from MDD patients. Chronic antidepressant treatment in these rats increased the expression of connexins. However, pharmacological GJC blockade in normal rodents decreased connexin expression and caused depressive-like behaviors. Furthermore, GJC dysfunction affects electrical conductance, metabolic coupling and secondary messengers, and inflammatory responses, which are consistent with current hypotheses on MDD. All these results provide a comprehensive overview of the neurobiology of MDD. CONCLUSION This review supports the hypothesis that the regulation of GJCs between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants.
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Affiliation(s)
- Qian Ren
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Shi-Feng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China. .,College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.
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26
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Acosta C, Anderson HD, Anderson CM. Astrocyte dysfunction in Alzheimer disease. J Neurosci Res 2017; 95:2430-2447. [PMID: 28467650 DOI: 10.1002/jnr.24075] [Citation(s) in RCA: 155] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 12/11/2022]
Abstract
Astrocytes are glial cells that are distributed throughout the central nervous system in an arrangement optimal for chemical and physical interaction with neuronal synapses and brain blood supply vessels. Neurotransmission modulates astrocytic excitability by activating an array of cell surface receptors and transporter proteins, resulting in dynamic changes in intracellular Ca2+ or Na+ . Ionic and electrogenic astrocytic changes, in turn, drive vital cell nonautonomous effects supporting brain function, including regulation of synaptic activity, neuronal metabolism, and regional blood supply. Alzheimer disease (AD) is associated with aberrant oligomeric amyloid β generation, which leads to extensive proliferation of astrocytes with a reactive phenotype and abnormal regulation of these processes. Astrocytic morphology, Ca2+ responses, extracellular K+ removal, glutamate transport, amyloid clearance, and energy metabolism are all affected in AD, resulting in a deleterious set of effects that includes glutamate excitotoxicity, impaired synaptic plasticity, reduced carbon delivery to neurons for oxidative phosphorylation, and dysregulated linkages between neuronal energy demand and regional blood supply. This review summarizes how astrocytes are affected in AD and describes how these changes are likely to influence brain function. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Crystal Acosta
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada
| | - Hope D Anderson
- Canadian Centre for Agri-food Research in Health and Medicine, St. Boniface Hospital Research, Winnipeg, Manitoba, Canada.,College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada
| | - Christopher M Anderson
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.,Neuroscience Research Program, Kleysen Institute for Advanced Medicine, Health Sciences Centre, Winnipeg, Manitoba, Canada
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27
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Cho WH, Barcelon E, Lee SJ. Optogenetic Glia Manipulation: Possibilities and Future Prospects. Exp Neurobiol 2016; 25:197-204. [PMID: 27790054 PMCID: PMC5081466 DOI: 10.5607/en.2016.25.5.197] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/01/2016] [Accepted: 10/08/2016] [Indexed: 12/22/2022] Open
Abstract
Our brains are composed of two distinct cell types: neurons and glia. Emerging data from recent investigations show that glial cells, especially astrocytes and microglia, are able to regulate synaptic transmission and thus brain information processing. This suggests that, not only neuronal activity, but communication between neurons and glia also plays a key role in brain function. Thus, it is currently well known that the physiology and pathophysiology of brain function can only be completely understood by considering the interplay between neurons and glia. However, it has not yet been possible to dissect glial cell type-specific roles in higher brain functions in vivo. Meanwhile, the recent development of optogenetics techniques has allowed investigators to manipulate neural activity with unprecedented temporal and spatial precision. Recently, a series of studies suggested the possibility of applying this cutting-edge technique to manipulate glial cell activity. This review briefly discusses the feasibility of optogenetic glia manipulation, which may provide a technical innovation in elucidating the in vivo role of glial cells in complex higher brain functions.
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Affiliation(s)
- Woo-Hyun Cho
- Department of Neuroscience and Physiology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 08826, Korea
| | - Ellane Barcelon
- Department of Neuroscience and Physiology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 08826, Korea
| | - Sung Joong Lee
- Department of Neuroscience and Physiology, and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 08826, Korea
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28
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Croft W, Reusch K, Tilunaite A, Russell NA, Thul R, Bellamy TC. Probabilistic encoding of stimulus strength in astrocyte global calcium signals. Glia 2015; 64:537-52. [PMID: 26651126 DOI: 10.1002/glia.22947] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022]
Abstract
Astrocyte calcium signals can range in size from subcellular microdomains to waves that spread through the whole cell (and into connected cells). The differential roles of such local or global calcium signaling are under intense investigation, but the mechanisms by which local signals evolve into global signals in astrocytes are not well understood, nor are the computational rules by which physiological stimuli are transduced into a global signal. To investigate these questions, we transiently applied receptor agonists linked to calcium signaling to primary cultures of cerebellar astrocytes. Astrocytes repetitively tested with the same stimulus responded with global signals intermittently, indicating that each stimulus had a defined probability for triggering a response. The response probability varied between agonists, increased with agonist concentration, and could be positively and negatively modulated by crosstalk with other signaling pathways. To better understand the processes determining the evolution of a global signal, we recorded subcellular calcium "puffs" throughout the whole cell during stimulation. The key requirement for puffs to trigger a global calcium wave following receptor activation appeared to be the synchronous release of calcium from three or more sites, rather than an increasing calcium load accumulating in the cytosol due to increased puff size, amplitude, or frequency. These results suggest that the concentration of transient stimuli will be encoded into a probability of generating a global calcium response, determined by the likelihood of synchronous release from multiple subcellular sites.
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Affiliation(s)
- Wayne Croft
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Katharina Reusch
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.,Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham, United Kingdom
| | - Agne Tilunaite
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Noah A Russell
- Department of Electrical and Electronic Engineering, University of Nottingham, Nottingham, United Kingdom
| | - Rüdiger Thul
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Tomas C Bellamy
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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29
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Kim JH, Kwon SJ, Stankewich MC, Huh GY, Glantz SB, Morrow JS. Reactive protoplasmic and fibrous astrocytes contain high levels of calpain-cleaved alpha 2 spectrin. Exp Mol Pathol 2015; 100:1-7. [PMID: 26551084 DOI: 10.1016/j.yexmp.2015.11.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/04/2015] [Indexed: 12/13/2022]
Abstract
Calpain, a family of calcium-dependent neutral proteases, plays important roles in neurophysiology and pathology through the proteolytic modification of cytoskeletal proteins, receptors and kinases. Alpha 2 spectrin (αII spectrin) is a major substrate for this protease family, and the presence of the αII spectrin breakdown product (αΙΙ spectrin BDP) in a cell is evidence of calpain activity triggered by enhanced intracytoplasmic Ca(2+) concentrations. Astrocytes, the most dynamic CNS cells, respond to micro-environmental changes or noxious stimuli by elevating intracytoplasmic Ca(2+) concentration to become activated. As one measure of whether calpains are involved with reactive glial transformation, we examined paraffin sections of the human cerebral cortex and white matter by immunohistochemistry with an antibody specific for the calpain-mediated αΙΙ spectrin BDP. We also performed conventional double immunohistochemistry as well as immunofluorescent studies utilizing antibodies against αΙΙ spectrin BDP as well as glial fibrillary acidic protein (GFAP). We found strong immunopositivity in selected protoplasmic and fibrous astrocytes, and in transitional forms that raise the possibility of some of fibrous astrocytes emerging from protoplasmic astrocytes. Immunoreactive astrocytes were numerous in brain sections from cases with severe cardiac and/or respiratory diseases in the current study as opposed to our previous study of cases without significant clinical conditions that failed to reveal such remarkable immunohistochemical alterations. Our study suggests that astrocytes become αΙΙ spectrin BDP immunopositive in various stages of activation, and that spectrin cleavage product persists even in fully reactive astrocytes. Immunohistochemistry for αΙΙ spectrin BDP thus marks reactive astrocytes, and highlights the likelihood that calpains and their proteolytic processing of spectrin participate in the morphologic and physiologic transition from resting protoplasmic astrocytes to reactive fibrous astrocytes.
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Affiliation(s)
- Jung H Kim
- Department of Pathology, Yale Univ. School of Medicine, 310 Cedar Street, New Haven, CT 06510-8023, USA.
| | - Soojung J Kwon
- Department of Pathology, Yale Univ. School of Medicine, 310 Cedar Street, New Haven, CT 06510-8023, USA
| | - Michael C Stankewich
- Department of Pathology, Yale Univ. School of Medicine, 310 Cedar Street, New Haven, CT 06510-8023, USA
| | - Gi-Yeong Huh
- Department of Forensic Medicine, School of Medicine, Pusan National University, Pusan, Korea
| | - Susan B Glantz
- Department of Pathology, Yale Univ. School of Medicine, 310 Cedar Street, New Haven, CT 06510-8023, USA
| | - Jon S Morrow
- Department of Pathology, Yale Univ. School of Medicine, 310 Cedar Street, New Haven, CT 06510-8023, USA
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30
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Emerging role of P2X7 receptors in CNS health and disease. Ageing Res Rev 2015; 24:328-42. [PMID: 26478005 DOI: 10.1016/j.arr.2015.10.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Accepted: 10/05/2015] [Indexed: 12/11/2022]
Abstract
Purinergic signalling in the brain is becoming an important focus in the study of CNS health and disease. Various purinergic receptors are found to be present in different brain cells in varying extent, which get activated upon binding of ATP or its analogues. Conventionally, ATP was considered only as a major metabolic fuel of the cell but its recognition as a neurotransmitter in early 1970s, brought meaningful insights in neuron glia crosstalk, participating in various physiological functions in the brain. P2X7R, a member of ligand gated purinergic receptor (P2X) family, is gaining attention in the field of neuroscience because of its emerging role in broad spectrum of ageing and age related neurological disorders. The aim of this review is to provide an overview about the structure and function of P2X7R highlighting its unique features which distinguish it from the other members of its family. This review critically analyzes the literature mentioning the details about the agonist and antagonist of the P2X7R. It also emphasizes the advancements in understanding the dual role of P2X7R in brain development and disorders inviting meaningful insights about its involvement in Alzheimer's disease, Huntington's disease, Multiple Sclerosis, Neuropathic pain, Spinal Cord Injury and NeuroAIDS. Exploring the roles of P2X7R in detail is critical to identify its therapeutic potential in the treatment of acute and chronic neurodegenerative diseases. Moreover, this review also helps to raise more interest in the neurobiology of the purinergic receptors and thus providing new avenues for future research.
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31
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Barger Z, Easton CR, Neuzil KE, Moody WJ. Early network activity propagates bidirectionally between hippocampus and cortex. Dev Neurobiol 2015; 76:661-72. [PMID: 26385616 DOI: 10.1002/dneu.22351] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 08/31/2015] [Accepted: 09/14/2015] [Indexed: 11/05/2022]
Abstract
Spontaneous activity in the developing brain helps refine neuronal connections before the arrival of sensory-driven neuronal activity. In mouse neocortex during the first postnatal week, waves of spontaneous activity originating from pacemaker regions in the septal nucleus and piriform cortex propagate through the neocortex. Using high-speed Ca(2+) imaging to resolve the spatiotemporal dynamics of wave propagation in parasagittal mouse brain slices, we show that the hippocampus can act as an additional source of neocortical waves. Some waves that originate in the hippocampus remain restricted to that structure, while others pause at the hippocampus-neocortex boundary and then propagate into the neocortex. Blocking GABAergic neurotransmission decreases the likelihood of wave propagation into neocortex, whereas blocking glutamatergic neurotransmission eliminates spontaneous and evoked hippocampal waves. A subset of hippocampal and cortical waves trigger Ca(2+) waves in astrocytic networks after a brief delay. Hippocampal waves accompanied by Ca(2+) elevation in astrocytes are more likely to propagate into the neocortex. Finally, we show that two structures in our preparation that initiate waves-the hippocampus and the piriform cortex-can be electrically stimulated to initiate propagating waves at lower thresholds than the neocortex, indicating that the intrinsic circuit properties of those regions are responsible for their pacemaker function.
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Affiliation(s)
- Zeke Barger
- Department of Biology, University of Washington, Seattle, Washington, 98195
| | - Curtis R Easton
- Department of Biology, University of Washington, Seattle, Washington, 98195
| | - Kevin E Neuzil
- Department of Biology, University of Washington, Seattle, Washington, 98195
| | - William J Moody
- Department of Biology, University of Washington, Seattle, Washington, 98195
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32
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Kanady JD, Munger SJ, Witte MH, Simon AM. Combining Foxc2 and Connexin37 deletions in mice leads to severe defects in lymphatic vascular growth and remodeling. Dev Biol 2015; 405:33-46. [PMID: 26079578 PMCID: PMC4529811 DOI: 10.1016/j.ydbio.2015.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 12/17/2022]
Abstract
Connexins (Cxs), proteins that are vital for intercellular communication in vertebrates, have recently been shown to play a critical role in lymphatic development. However, our knowledge is currently limited regarding the functional relationships of Cxs with other proteins and signaling pathways. Cell culture studies have shown that Cx37 is necessary for coordinated activation of the transcription factor NFATc1, which cooperates with Foxc2 (another transcription factor) during lymphatic endothelial development. These data suggest that Cxs, Foxc2, and NFATc1 are part of a common developmental pathway. Here, we present a detailed characterization of Foxc2(+/-)Cx37(-/-) mice, demonstrating that lymphatic network architecture and valve formation rely on the concurrent embryonic expression and function of Foxc2 and Cx37. Foxc2(+/-)Cx37(-/-) mice have lymphedema in utero, exhibit craniofacial abnormalities, show severe dilation of intestinal lymphatics, display abnormal lacteal development, lack lymphatic valves, and typically die perinatally (outcomes not seen in Foxc2(+/-) or Cx37(-/-) mice separately). We provide a rigorous, quantitative documentation of lymphatic vascular network changes that highlight the specific structural alterations that occur in Foxc2(+/-)Cx37(-/-) mice. These data provide further evidence suggesting that Foxc2 and Cx37 are elements in a common molecular pathway directing lymphangiogenesis.
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Affiliation(s)
- John D Kanady
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
| | | | - Marlys H Witte
- Department of Surgery, University of Arizona, Tucson, AZ 85724, USA.
| | - Alexander M Simon
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
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33
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Phookan S, Sutton AC, Walling I, Smith A, O'Connor KA, Campbell JC, Calos M, Yu W, Pilitsis JG, Brotchie JM, Shin DS. Gap junction blockers attenuate beta oscillations and improve forelimb function in hemiparkinsonian rats. Exp Neurol 2015; 265:160-70. [PMID: 25622779 DOI: 10.1016/j.expneurol.2015.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 01/14/2015] [Indexed: 11/25/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disease characterized by akinesia, bradykinesia, resting tremors and postural instability. Although various models have been developed to explain basal ganglia (BG) pathophysiology in PD, the recent reports that dominant beta (β) oscillations (12-30Hz) in BG nuclei of PD patients and parkinsonian animals coincide with motor dysfunction has led to an emerging idea that these oscillations may be a characteristic of PD. Due to the recent realization of these oscillations, the cellular and network mechanism(s) that underlie this process remain ill-defined. Here, we postulate that gap junctions (GJs) can contribute to β oscillations in the BG of hemiparkinsonian rats and inhibiting their activity will disrupt neuronal synchrony, diminish these oscillations and improve motor function. To test this, we injected the GJ blockers carbenoxolone (CBX) or octanol in the right globus pallidus externa (GPe) of anesthetized hemiparkinsonian rats and noted whether subsequent changes in β oscillatory activity occurred using in vivo electrophysiology. We found that systemic treatment of 200mg/kg CBX attenuated normalized GPe β oscillatory activity from 6.10±1.29 arbitrary units (A.U.) (pre-CBX) to 2.48±0.87 A.U. (post-CBX) with maximal attenuation occurring 90.0±20.5min after injection. The systemic treatment of octanol (350mg/kg) also decreased β oscillatory activity in a similar manner to CBX treatment with β oscillatory activity decreasing from 3.58±0.89 (pre-octanol) to 2.57±1.08 after octanol injection. Next, 1μl CBX (200mg/kg) was directly injected into the GPe of anesthetized hemiparkinsonian rats; 59.2±19.0min after injection, β oscillations in this BG nucleus decreased from 3.62±1.17 A.U. to 1.67±0.62 A.U. Interestingly, we were able to elicit β oscillations in the GPe of naive non-parkinsonian rats by increasing GJ activity with 1μl trimethylamine (TMA, 500nM). Finally, we systemically injected CBX (200mg/kg) into hemiparkinsonian rats which attenuated dominant β oscillations in the right GPe and also improved left forepaw akinesia in the step test. Conversely, direct injection of TMA into the right GPe of naive rats induced contralateral left forelimb akinesia. Overall, our results suggest that GJs contribute to β oscillations in the GPe of hemiparkinsonian rats.
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Affiliation(s)
- Sujoy Phookan
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Alexander C Sutton
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Ian Walling
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Autumn Smith
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Katherine A O'Connor
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Joannalee C Campbell
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Megan Calos
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Wilson Yu
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA
| | - Julie G Pilitsis
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA; Division of Neurosurgery, Albany Medical Center, Albany, NY USA
| | - Jonathan M Brotchie
- Division of Brain Imaging and Behavioral Neuroscience Systems, Toronto Western Research Institute, Toronto Western Hospital, Toronto, ON, Canada
| | - Damian S Shin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY USA.
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34
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Sheridan GK, Moeendarbary E, Pickering M, O'Connor JJ, Murphy KJ. Theta-burst stimulation of hippocampal slices induces network-level calcium oscillations and activates analogous gene transcription to spatial learning. PLoS One 2014; 9:e100546. [PMID: 24950243 PMCID: PMC4065069 DOI: 10.1371/journal.pone.0100546] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/28/2014] [Indexed: 01/24/2023] Open
Abstract
Over four decades ago, it was discovered that high-frequency stimulation of the dentate gyrus induces long-term potentiation (LTP) of synaptic transmission. LTP is believed to underlie how we process and code external stimuli before converting it to salient information that we store as 'memories'. It has been shown that rats performing spatial learning tasks display theta-frequency (3–12 Hz) hippocampal neural activity. Moreover, administering theta-burst stimulation (TBS) to hippocampal slices can induce LTP. TBS triggers a sustained rise in intracellular calcium [Ca2+]i in neurons leading to new protein synthesis important for LTP maintenance. In this study, we measured TBS-induced [Ca2+]i oscillations in thousands of cells at increasing distances from the source of stimulation. Following TBS, a calcium wave propagates radially with an average speed of 5.2 µm/s and triggers multiple and regular [Ca2+]i oscillations in the hippocampus. Interestingly, the number and frequency of [Ca2+]i fluctuations post-TBS increased with respect to distance from the electrode. During the post-tetanic phase, 18% of cells exhibited 3 peaks in [Ca2+]i with a frequency of 17 mHz, whereas 2.3% of cells distributed further from the electrode displayed 8 [Ca2+]i oscillations at 33 mHz. We suggest that these observed [Ca2+]i oscillations could lead to activation of transcription factors involved in synaptic plasticity. In particular, the transcription factor, NF-κB, has been implicated in memory formation and is up-regulated after LTP induction. We measured increased activation of NF-κB 30 min post-TBS in CA1 pyramidal cells and also observed similar temporal up-regulation of NF-κB levels in CA1 neurons following water maze training in rats. Therefore, TBS of hippocampal slice cultures in vitro can mimic the cell type-specific up-regulations in activated NF-κB following spatial learning in vivo. This indicates that TBS may induce similar transcriptional changes to spatial learning and that TBS-triggered [Ca2+]i oscillations could activate memory-associated gene expression.
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Affiliation(s)
- Graham K. Sheridan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | | | - Mark Pickering
- School of Medicine and Medical Science, Health Sciences Centre, University College Dublin, Dublin, Ireland
| | - John J. O'Connor
- UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin, Ireland
| | - Keith J. Murphy
- Neurotherapeutics Research Group, UCD School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Dublin, Ireland
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35
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Mitterauer BJ. Model of the Reticular Formation of the Brainstem Based on Glial-Neuronal Interactions. Cognit Comput 2014; 7:64-73. [PMID: 25685240 PMCID: PMC4320307 DOI: 10.1007/s12559-014-9260-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 03/17/2014] [Indexed: 11/25/2022]
Abstract
A new model of the reticular formation of the brainstem is proposed. It refers to the neuronal and glial cell systems. Thus, it is biomimetically founded. The reticular formation generates modes of behavior (sleeping, eating, etc.) and commands all behavior according to the most appropriate environmental information. The reticular formation works on an abductive logic and is dominated by a redundancy of potential command. Formally, a special mode of behavior is represented by a comprehensive cycle (Hamilton loop) located in the glial network (syncytium) and embodied in gap junctional plaques. Whereas for the neuronal network of the reticular formation, a computer simulation has already been presented; here, the necessary devices for computation in the whole network are outlined.
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Affiliation(s)
- Bernhard J. Mitterauer
- Volitronics-Institute for Basic Research, Psychopathology and Brain Philosophy, Gotthard Guenther Archives, Autobahnweg 7, 5071 Wals/Salzburg, Austria
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Pires M, Raischel F, Vaz SH, Cruz-Silva A, Sebastião AM, Lind PG. Modeling the functional network of primary intercellular Ca2+ wave propagation in astrocytes and its application to study drug effects. J Theor Biol 2014; 356:201-12. [PMID: 24813072 DOI: 10.1016/j.jtbi.2014.04.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 03/17/2014] [Accepted: 04/17/2014] [Indexed: 11/15/2022]
Abstract
We introduce a simple procedure of multivariate signal analysis to uncover the functional connectivity among cells composing a living tissue and describe how to apply it for extracting insight on the effect of drugs in the tissue. The procedure is based on the covariance matrix of time resolved activity signals. By determining the time-lag that maximizes covariance, one derives the weight of the corresponding connection between cells. Introducing simple constraints, it is possible to conclude whether pairs of cells are functionally connected and in which direction. After testing the method against synthetic data we apply it to study intercellular propagation of Ca(2+) waves in astrocytes following an external stimulus, with the aim of uncovering the functional cellular connectivity network. Our method proves to be particularly suited for this type of networking signal propagation where signals are pulse-like and have short time-delays, and is shown to be superior to standard methods, namely a multivariate Granger algorithm. Finally, based on the statistical analysis of the connection weight distribution, we propose simple measures for assessing the impact of drugs on the functional connectivity between cells.
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Affiliation(s)
- Marcelo Pires
- Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande 1649-003 Lisboa, Portugal; Departamento de Física, Universidade Federal do Amapá, Jardim Marco Zero, 68903-419 Macapá/AP, Brazil
| | - Frank Raischel
- Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande 1649-003 Lisboa, Portugal; Centro de Geofísica, Instituto Dom Luiz, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Sandra H Vaz
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Unidade de Neurociências, Instituto de Medicina Molecular, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Andreia Cruz-Silva
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Unidade de Neurociências, Instituto de Medicina Molecular, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ana M Sebastião
- Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal; Unidade de Neurociências, Instituto de Medicina Molecular, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Pedro G Lind
- Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, Campo Grande 1649-003 Lisboa, Portugal; Institute für Physik and ForWind, Carl-von-Ossietzky Universität Oldenburg, DE-26111 Oldenburg, Germany.
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Xu Q, Cheong YK, He SQ, Tiwari V, Liu J, Wang Y, Raja SN, Li J, Guan Y, Li W. Suppression of spinal connexin 43 expression attenuates mechanical hypersensitivity in rats after an L5 spinal nerve injury. Neurosci Lett 2014; 566:194-199. [PMID: 24631560 PMCID: PMC4007756 DOI: 10.1016/j.neulet.2014.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/27/2014] [Accepted: 03/01/2014] [Indexed: 02/07/2023]
Abstract
Activation of spinal astrocytes may contribute to neuropathic pain. Adjacent astrocytes can make direct communication through gap junctions formed by connexin 43 (Cx43) in the central nervous system. Yet, the role of spinal astroglial gap junctions in neuropathic pain is not fully understood. Since Cx43 is the connexin isoform expressed preferentially in astrocytes in the spinal cord, we used a small interfering RNA (siRNA) approach to examine whether suppression of spinal Cx43 expression inhibits mechanical hypersensitivity in rats after an L5 spinal nerve ligation (SNL). SNL rats were administered intrathecal Cx43 siRNA (3μg/15μl, twice/day) or an equal amount of mismatch siRNA (control) on days 14-17 post-SNL. Cx43 siRNA, but not mismatch siRNA, alleviated mechanical hypersensitivity in SNL rats. Furthermore, Western blot analysis showed that the pain inhibition induced by Cx43 siRNA correlated with downregulation of Cx43 expression, but not that of Cx36 (the neuronal gap junction protein) or glial fibrillary acidic protein (GFAP, a marker for reactive astrocytes) in the spinal cord of SNL rats. Western blot analysis and immunohistochemistry also showed that SNL increased GFAP expression, but decreased Cx43 expression, in spinal cord. Our results provide direct evidence that selective suppression of spinal Cx43 after nerve injury alleviates neuropathic mechanical hypersensitivity. These findings suggest that in the spinal cord, the enhanced function of astroglial gap junctions, especially those formed by Cx43, may be important to neuropathic pain in SNL rats.
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Affiliation(s)
- Qian Xu
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Yong-Kwan Cheong
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
- Department of Anesthesiology and Pain Medicine, School of Medicine, Wonkwang University, Iksan, Korea
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Jian Liu
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Yun Wang
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China
| | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Jinheng Li
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Weiyan Li
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
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Lallouette J, De Pittà M, Ben-Jacob E, Berry H. Sparse short-distance connections enhance calcium wave propagation in a 3D model of astrocyte networks. Front Comput Neurosci 2014; 8:45. [PMID: 24795613 PMCID: PMC3997029 DOI: 10.3389/fncom.2014.00045] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 03/27/2013] [Indexed: 11/13/2022] Open
Abstract
Traditionally, astrocytes have been considered to couple via gap-junctions into a syncytium with only rudimentary spatial organization. However, this view is challenged by growing experimental evidence that astrocytes organize as a proper gap-junction mediated network with more complex region-dependent properties. On the other hand, the propagation range of intercellular calcium waves (ICW) within astrocyte populations is as well highly variable, depending on the brain region considered. This suggests that the variability of the topology of gap-junction couplings could play a role in the variability of the ICW propagation range. Since this hypothesis is very difficult to investigate with current experimental approaches, we explore it here using a biophysically realistic model of three-dimensional astrocyte networks in which we varied the topology of the astrocyte network, while keeping intracellular properties and spatial cell distribution and density constant. Computer simulations of the model suggest that changing the topology of the network is indeed sufficient to reproduce the distinct ranges of ICW propagation reported experimentally. Unexpectedly, our simulations also predict that sparse connectivity and restriction of gap-junction couplings to short distances should favor propagation while long–distance or dense connectivity should impair it. Altogether, our results provide support to recent experimental findings that point toward a significant functional role of the organization of gap-junction couplings into proper astroglial networks. Dynamic control of this topology by neurons and signaling molecules could thus constitute a new type of regulation of neuron-glia and glia-glia interactions.
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Affiliation(s)
- Jules Lallouette
- EPI Beagle, INRIA Rhône-Alpes Villeurbanne, France ; LIRIS, UMR 5205 CNRS-INSA, Université de Lyon Villeurbanne, France
| | - Maurizio De Pittà
- EPI Beagle, INRIA Rhône-Alpes Villeurbanne, France ; LIRIS, UMR 5205 CNRS-INSA, Université de Lyon Villeurbanne, France ; School of Physics and Astronomy, Tel Aviv University Ramat Aviv, Israel
| | - Eshel Ben-Jacob
- School of Physics and Astronomy, Tel Aviv University Ramat Aviv, Israel ; Center for Theoretical Biological Physics, Rice University Houston, TX, USA
| | - Hugues Berry
- EPI Beagle, INRIA Rhône-Alpes Villeurbanne, France ; LIRIS, UMR 5205 CNRS-INSA, Université de Lyon Villeurbanne, France
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Xu Q, Cheong YK, Yang F, Tiwari V, Li J, Liu J, Raja SN, Li W, Guan Y. Intrathecal carbenoxolone inhibits neuropathic pain and spinal wide-dynamic range neuronal activity in rats after an L5 spinal nerve injury. Neurosci Lett 2014; 563:45-50. [PMID: 24486838 DOI: 10.1016/j.neulet.2014.01.042] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/10/2014] [Accepted: 01/21/2014] [Indexed: 12/30/2022]
Abstract
Spinal glial gap junctions may play an important role in dorsal horn neuronal sensitization and neuropathic pain. In rats after an L5 spinal nerve ligation (SNL), we examined the effects of intrathecal injection of carbenoxolone (CBX), a gap junction decoupler, on neuropathic pain manifestations and on wide-dynamic range (WDR) neuronal activity in vivo. Intrathecal injection of CBX dose-dependently (0.1-50 μg, 10 μl) inhibited mechanical hypersensitivity in rats at 2-3 weeks post-SNL. However, the same doses of glycyrrhizic acid (an analogue of CBX that does not affect gap junctions) and mefloquine hydrochloride (a selective neuronal gap junction decoupler) were ineffective. Intrathecal CBX (5μg) also attenuated heat hypersensitivity in SNL rats. Further, rats did not develop tachyphylaxis to CBX-induced inhibition of mechanical hypersensitivity after repetitive drug treatments (25 μg/day) during days 14-16 post-SNL. Electrophysiological study in SNL rats showed that spinal topical application of CBX (100 μg, 50 μl), which mimics intrathecal drug administration, attenuated WDR neuronal responses to mechanical stimuli and to repetitive intracutaneous electrical stimuli (0.5 Hz) that induce windup, a short-form of activity-dependent neuronal sensitization. The current findings suggest that the inhibition of neuropathic pain manifestations by intrathecal injection of CBX in SNL rats may involve an inhibition of glial gap junctions and an attenuation of WDR neuronal activity in the dorsal horn.
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Affiliation(s)
- Qian Xu
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China; Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Yong-Kwan Cheong
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA; Department of Anesthesiology and Pain Medicine, School of Medicine, Wonkwang University, Iksan, Republic of Korea
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Jinheng Li
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Jian Liu
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Weiyan Li
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
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Yoon SY, Robinson CR, Zhang H, Dougherty PM. Spinal astrocyte gap junctions contribute to oxaliplatin-induced mechanical hypersensitivity. THE JOURNAL OF PAIN 2013; 14:205-14. [PMID: 23374942 DOI: 10.1016/j.jpain.2012.11.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/29/2012] [Accepted: 11/07/2012] [Indexed: 01/07/2023]
Abstract
UNLABELLED Spinal glial cells contribute to the development of many types of inflammatory and neuropathic pain. Here the contribution of spinal astrocytes and astrocyte gap junctions to oxaliplatin-induced mechanical hypersensitivity was explored. The expression of glial fibrillary acidic protein (GFAP) in spinal dorsal horn was significantly increased at day 7 but recovered at day 14 after oxaliplatin treatment, suggesting a transient activation of spinal astrocytes by chemotherapy. Astrocyte-specific gap junction protein connexin 43 (Cx43) was significantly increased in dorsal horn at both day 7 and day 14 following chemotherapy, but neuronal (connexin 36 [Cx36]) and oligodendrocyte (connexin 32 [Cx32]) gap junction proteins did not show any change. Blockade of astrocyte gap junction with carbenoxolone (CBX) prevented oxaliplatin-induced mechanical hypersensitivity in a dose-dependent manner and the increase of spinal GFAP expression, but had no effect once the mechanical hypersensitivity induced by oxaliplatin had fully developed. These results suggest that oxaliplatin chemotherapy induces the activation of spinal astrocytes and this is accompanied by increased expression of astrocyte-astrocyte gap junction connections via Cx43. These alterations in spinal astrocytes appear to contribute to the induction but not the maintenance of oxaliplatin-induced mechanical hypersensitivity. Combined, these results suggest that targeting spinal astrocyte/astrocyte-specific gap junction could be a new therapeutic strategy to prevent oxaliplatin-induced neuropathy. PERSPECTIVE Spinal astrocytes but not microglia were recently shown to be recruited in paclitaxel-related chemoneuropathy. Here, spinal astrocyte gap junctions are shown to play an important role in the induction of oxaliplatin neuropathy.
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Affiliation(s)
- Seo-Yeon Yoon
- Laboratory of Molecular Signal Transduction, Center for Neural Science, Korea Institute of Science and Technology, Seoul, South Korea
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Lemcke H, Nittel ML, Weiss DG, Kuznetsov SA. Neuronal differentiation requires a biphasic modulation of gap junctional intercellular communication caused by dynamic changes of connexin43 expression. Eur J Neurosci 2013; 38:2218-28. [PMID: 23607708 DOI: 10.1111/ejn.12219] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 11/30/2022]
Abstract
It was suggested that gap junctional intercellular communication (GJIC) and connexin (Cx) proteins play a crucial role in cell proliferation and differentiation. However, the mechanisms of cell coupling in regulating cell fate during embryonic development are poorly understood. To study the role of GJIC in proliferation and differentiation, we used a human neural progenitor cell line derived from the ventral mesencephalon. Fluorescence recovery after photobleaching (FRAP) showed that dye coupling was extensive in proliferating cells but diminished after the induction of differentiation, as indicated by a 2.5-fold increase of the half-time of fluorescence recovery. Notably, recovery half-time decreased strongly (five-fold) in the later stage of differentiation. Western blot analysis revealed a similar time-dependent expression profile of Cx43, acting as the main gap junction-forming protein. Interestingly, large amounts of cytoplasmic Cx43 were retained mainly in the Golgi network during proliferation but decreased when differentiation was induced. Furthermore, down-regulation of Cx43 by small interfering RNA reduced functional cell coupling, which in turn resulted in a 50% decrease of both the proliferation rate and neuronal differentiation. Our findings suggest a dual function of Cx43 and GJIC in the neural development of ReNcell VM197 human progenitor cells. GJIC accompanied by high Cx43 expression is necessary (1) to maintain cells in a proliferative state and (2) to complete neuronal differentiation, including the establishment of a neural network. However, uncoupling of cells is crucial in the early stage of differentiation during cell fate commitment.
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Affiliation(s)
- Heiko Lemcke
- Department of Animal Physiology, Cell Biology and Biosystems Technology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Str. 3, D-18059, Rostock, Germany
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Wu X, Pan L, Liu Y, Jiang P, Lee I, Drevensek-Olenik I, Zhang X, Xu J. Cell-cell communication induces random spikes of spontaneous calcium oscillations in multi-BV-2 microglial cells. Biochem Biophys Res Commun 2013; 431:664-9. [PMID: 23357419 DOI: 10.1016/j.bbrc.2013.01.064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 01/16/2013] [Indexed: 01/11/2023]
Abstract
As the first and main form of active immune defense in the central nervous system, microglial cells usually exhibit complicated intracellular calcium (Ca²⁺) activity that can regulate the downstream components of signaling cascades. In the present work, spontaneous oscillations of the cytosolic calcium concentration ([Ca²⁺]c) in multi-BV-2 microglial cells were observed by video microscopy. These cells exhibited random spikes of Ca²⁺ oscillations. Cross-correlation analysis of the temporal dependence of the oscillations indicated the existence of cell-cell communication mediated by extracellular messengers. Numerical simulations based on a simple mathematical model suggested that these communications could induce random spikes of spontaneous Ca oscillations in the multi-cell system. Short-time imaging analysis of random spikes in different regions of a single cell showed that spontaneous Ca²⁺ oscillations resulted from Ca²⁺ wave generated by other cells as well as from calcium elevation inside the cell. Taken together, our data demonstrate that cell-cell communication existed between the BV-2 microglial cells in vitro and further resulted in the random spikes of spontaneous Ca²⁺ oscillations.
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Affiliation(s)
- Xian Wu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics School, Nankai University, Tianjin 300457, PR China
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Abstract
Intercellular calcium (Ca(2+)) waves (ICWs) represent the propagation of increases in intracellular Ca(2+) through a syncytium of cells and appear to be a fundamental mechanism for coordinating multicellular responses. ICWs occur in a wide diversity of cells and have been extensively studied in vitro. More recent studies focus on ICWs in vivo. ICWs are triggered by a variety of stimuli and involve the release of Ca(2+) from internal stores. The propagation of ICWs predominately involves cell communication with internal messengers moving via gap junctions or extracellular messengers mediating paracrine signaling. ICWs appear to be important in both normal physiology as well as pathophysiological processes in a variety of organs and tissues including brain, liver, retina, cochlea, and vascular tissue. We review here the mechanisms of initiation and propagation of ICWs, the key intra- and extracellular messengers (inositol 1,4,5-trisphosphate and ATP) mediating ICWs, and the proposed physiological functions of ICWs.
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Affiliation(s)
- Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Faculty of Medicine & Health Sciences, Ghent University, Ghent, Belgium.
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Parpura V, Verkhratsky A. The astrocyte excitability brief: From receptors to gliotransmission. Neurochem Int 2012; 61:610-21. [DOI: 10.1016/j.neuint.2011.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 11/14/2011] [Accepted: 12/01/2011] [Indexed: 01/23/2023]
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45
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Foo K, Blumenthal L, Man HY. Regulation of neuronal bioenergy homeostasis by glutamate. Neurochem Int 2012; 61:389-96. [PMID: 22709672 DOI: 10.1016/j.neuint.2012.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 06/07/2012] [Accepted: 06/08/2012] [Indexed: 01/24/2023]
Abstract
Bioenergy homeostasis is crucial in maintaining normal cell function and survival and it is thus important to understand cellular mechanisms underlying its regulation. Neurons use a large amount of ATP to maintain membrane potential and synaptic communication, making the brain the most energy consuming organ in the body. Glutamate mediates a large majority of synaptic transmission which is responsible for the expression of neural plasticity and higher brain functions. Most of the energy cost is attributable to the glutamatergic system; under pathological conditions such as stroke and brain ischemia, neural energy depletion is accompanied by a massive release of glutamate. However, the specific cellular processes implicated in glutamate-dependent bioenergy dynamics are not well understood. We find that glutamate induces a rapid and dramatic reduction of ATP levels in neurons, through reduced ATP genesis and elevated consumption. ATP reduction depends on NMDA receptor activity, but is not a result of neuronal firing, gap junction-mediated leaking or intracellular signaling. Similar changes in ATP levels are also induced by synaptic glutamate accumulation following suppression of glutamate transporter activity. Furthermore, the glutamate-induced ATP down-regulation is blocked by the sodium pump inhibitor ouabain, suggesting the sodium pump as the primary energy consumer during glutamate stimulation. These data suggest the important role of glutamate in the control of cellular ATP homeostasis.
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Affiliation(s)
- Katrina Foo
- Department of Biology, Boston University, 5 Cummington St., Boston, MA 02215, USA
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Hill EJ, Jiménez-González C, Tarczyluk M, Nagel DA, Coleman MD, Parri HR. NT2 derived neuronal and astrocytic network signalling. PLoS One 2012; 7:e36098. [PMID: 22567128 PMCID: PMC3342170 DOI: 10.1371/journal.pone.0036098] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 03/30/2012] [Indexed: 12/16/2022] Open
Abstract
A major focus of stem cell research is the generation of neurons that may then be implanted to treat neurodegenerative diseases. However, a picture is emerging where astrocytes are partners to neurons in sustaining and modulating brain function. We therefore investigated the functional properties of NT2 derived astrocytes and neurons using electrophysiological and calcium imaging approaches. NT2 neurons (NT2Ns) expressed sodium dependent action potentials, as well as responses to depolarisation and the neurotransmitter glutamate. NT2Ns exhibited spontaneous and coordinated calcium elevations in clusters and in extended processes, indicating local and long distance signalling. Tetrodotoxin sensitive network activity could also be evoked by electrical stimulation. Similarly, NT2 astrocytes (NT2As) exhibited morphology and functional properties consistent with this glial cell type. NT2As responded to neuronal activity and to exogenously applied neurotransmitters with calcium elevations, and in contrast to neurons, also exhibited spontaneous rhythmic calcium oscillations. NT2As also generated propagating calcium waves that were gap junction and purinergic signalling dependent. Our results show that NT2 derived astrocytes exhibit appropriate functionality and that NT2N networks interact with NT2A networks in co-culture. These findings underline the utility of such cultures to investigate human brain cell type signalling under controlled conditions. Furthermore, since stem cell derived neuron function and survival is of great importance therapeutically, our findings suggest that the presence of complementary astrocytes may be valuable in supporting stem cell derived neuronal networks. Indeed, this also supports the intriguing possibility of selective therapeutic replacement of astrocytes in diseases where these cells are either lost or lose functionality.
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Affiliation(s)
- Eric J. Hill
- Aston Research Centre into Healthy Ageing (ARCHA), Aston University, Birmingham, West Midlands, United Kingdom
| | | | - Marta Tarczyluk
- Aston Research Centre into Healthy Ageing (ARCHA), Aston University, Birmingham, West Midlands, United Kingdom
| | - David A. Nagel
- School of Life and Health Sciences, Aston University, Birmingham, West Midlands, United Kingdom
| | - Michael D. Coleman
- School of Life and Health Sciences, Aston University, Birmingham, West Midlands, United Kingdom
| | - H. Rheinallt Parri
- School of Life and Health Sciences, Aston University, Birmingham, West Midlands, United Kingdom
- * E-mail:
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Franke H, Verkhratsky A, Burnstock G, Illes P. Pathophysiology of astroglial purinergic signalling. Purinergic Signal 2012; 8:629-57. [PMID: 22544529 DOI: 10.1007/s11302-012-9300-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 02/01/2012] [Indexed: 12/13/2022] Open
Abstract
Astrocytes are fundamental for central nervous system (CNS) physiology and are the fulcrum of neurological diseases. Astroglial cells control development of the nervous system, regulate synaptogenesis, maturation, maintenance and plasticity of synapses and are central for nervous system homeostasis. Astroglial reactions determine progression and outcome of many neuropathologies and are critical for regeneration and remodelling of neural circuits following trauma, stroke, ischaemia or neurodegenerative disorders. They secrete multiple neurotransmitters and neurohormones to communicate with neurones, microglia and the vascular walls of capillaries. Signalling through release of ATP is the most widespread mean of communication between astrocytes and other types of neural cells. ATP serves as a fast excitatory neurotransmitter and has pronounced long-term (trophic) roles in cell proliferation, growth, and development. During pathology, ATP is released from damaged cells and acts both as a cytotoxic factor and a proinflammatory mediator, being a universal "danger" signal. In this review, we summarise contemporary knowledge on the role of purinergic receptors (P2Rs) in a variety of diseases in relation to changes of astrocytic functions and nucleotide signalling. We have focussed on the role of the ionotropic P2X and metabotropic P2YRs working alone or in concert to modify the release of neurotransmitters, to activate signalling cascades and to change the expression levels of ion channels and protein kinases. All these effects are of great importance for the initiation, progression and maintenance of astrogliosis-the conserved and ubiquitous glial defensive reaction to CNS pathologies. We highlighted specific aspects of reactive astrogliosis, especially with respect to the involvement of the P2X(7) and P2Y(1)R subtypes. Reactive astrogliosis exerts both beneficial and detrimental effects in a context-specific manner determined by distinct molecular signalling cascades. Understanding the role of purinergic signalling in astrocytes is critical to identifying new therapeutic principles to treat acute and chronic neurological diseases.
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Affiliation(s)
- Heike Franke
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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Verkhratsky A, Rodríguez JJ, Parpura V. Calcium signalling in astroglia. Mol Cell Endocrinol 2012; 353:45-56. [PMID: 21945602 DOI: 10.1016/j.mce.2011.08.039] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/28/2011] [Accepted: 08/31/2011] [Indexed: 12/15/2022]
Abstract
Astroglia possess excitability based on movements of Ca(2+) ions between intracellular compartments and plasmalemmal Ca(2+) fluxes. This "Ca(2+) excitability" is controlled by several families of proteins located in the plasma membrane, within the cytosol and in the intracellular organelles, most notably in the endoplasmic reticulum (ER) and mitochondria. Accumulation of cytosolic Ca(2+) can be caused by the entry of Ca(2+) from the extracellular space through ionotropic receptors and store-operated channels expressed in astrocytes. Plasmalemmal Ca(2+) ATP-ase and sodium-calcium exchanger extrude cytosolic Ca(2+) to the extracellular space; the exchanger can also operate in reverse, depending of the intercellular Na(+) concentration, to deliver Ca(2+) to the cytosol. The ER internal store possesses inositol 1,4,5-trisphosphate receptors which can be activated upon stimulation of astrocytes through a multiple plasma membrane metabotropic G-protein coupled receptors. This leads to release of Ca(2+) from the ER and its elevation in the cytosol, the level of which can be modulated by mitochondria. The mitochondrial uniporter takes up Ca(2+) into the matrix, while free Ca(2+) exits the matrix through the mitochondrial Na(+)/Ca(2+) exchanger as well as via transient openings of the mitochondrial permeability transition pore. One of the prominent consequences of astroglial Ca(2+) excitability is gliotransmission, a release of transmitters from astroglia which can lead to signalling to adjacent neurones.
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Abstract
The name astroglia unifies many non-excitable neural cells that act as primary homeostatic cells in the nervous system. Neuronal activity triggers multiple homeostatic responses of astroglia that include increase in metabolic activity and synthesis of neuronal preferred energy substrate lactate, clearance of neurotransmitters and buffering of extracellular K(+) ions to name but a few. Many (if not all) of astroglial homeostatic responses are controlled by dynamic changes in the cytoplasmic concentration of two cations, Ca(2+) and Na(+). Intracellular concentration of these ions is tightly controlled by several transporters and can be rapidly affected by the activation of respective fluxes through ionic channels or ion exchangers. Here, we provide a comprehensive review of astroglial Ca(2+) and Na(+) signalling.
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Mitterauer BJ. Qualitative Information Processing in Tripartite Synapses: A Hypothetical Model. Cognit Comput 2011. [DOI: 10.1007/s12559-011-9115-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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