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Mitochondrial Ca2+ handling as a cell signaling hub: lessons from astrocyte function. Essays Biochem 2023; 67:63-75. [PMID: 36636961 DOI: 10.1042/ebc20220094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/16/2022] [Accepted: 12/22/2022] [Indexed: 01/14/2023]
Abstract
Astrocytes are a heterogenous population of macroglial cells spread throughout the central nervous system with diverse functions, expression signatures, and intricate morphologies. Their subcellular compartments contain a distinct range of mitochondria, with functional microdomains exhibiting widespread activities, such as controlling local metabolism and Ca2+ signaling. Ca2+ is an ion of utmost importance, both physiologically and pathologically, and participates in critical central nervous system processes, including synaptic plasticity, neuron-astrocyte integration, excitotoxicity, and mitochondrial physiology and metabolism. The mitochondrial Ca2+ handling system is formed by the mitochondrial Ca2+ uniporter complex (MCUc), which mediates Ca2+ influx, and the mitochondrial Na+/Ca2+ exchanger (NCLX), responsible for most mitochondrial Ca2+ efflux, as well as additional components, including the mitochondrial permeability transition pore (mtPTP). Over the last decades, mitochondrial Ca2+ handling has been shown to be key for brain homeostasis, acting centrally in physiopathological processes such as astrogliosis, astrocyte-neuron activity integration, energy metabolism control, and neurodegeneration. In this review, we discuss the current state of knowledge regarding the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis.
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2
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Abstract
Inositol 1,4,5-trisphosphate (IP3) plays a key role in calcium signaling. After stimulation, it diffuses from the plasma membrane where it is produced to the endoplasmic reticulum where its receptors are localized. Based on in vitro measurements, IP3 was long thought to be a global messenger characterized by a diffusion coefficient of ~ 280 μm2s-1. However, in vivo observations revealed that this value does not match with the timing of localized Ca2+ increases induced by the confined release of a non-metabolizable IP3 analog. A theoretical analysis of these data concluded that in intact cells diffusion of IP3 is strongly hindered, leading to a 30-fold reduction of the diffusion coefficient. Here, we performed a new computational analysis of the same observations using a stochastic model of Ca2+ puffs. Our simulations concluded that the value of the effective IP3 diffusion coefficient is close to 100 μm2s-1. Such moderate reduction with respect to in vitro estimations quantitatively agrees with a buffering effect by non-fully bound inactive IP3 receptors. The model also reveals that IP3 spreading is not much affected by the endoplasmic reticulum, which represents an obstacle to the free displacement of molecules, but can be significantly increased in cells displaying elongated, 1-dimensional like geometries.
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3
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Alosaimi F, Boonstra JT, Tan S, Temel Y, Jahanshahi A. The role of neurotransmitter systems in mediating deep brain stimulation effects in Parkinson’s disease. Front Neurosci 2022; 16:998932. [PMID: 36278000 PMCID: PMC9579467 DOI: 10.3389/fnins.2022.998932] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/14/2022] [Indexed: 11/24/2022] Open
Abstract
Deep brain stimulation (DBS) is among the most successful paradigms in both translational and reverse translational neuroscience. DBS has developed into a standard treatment for movement disorders such as Parkinson’s disease (PD) in recent decades, however, specific mechanisms behind DBS’s efficacy and side effects remain unrevealed. Several hypotheses have been proposed, including neuronal firing rate and pattern theories that emphasize the impact of DBS on local circuitry but detail distant electrophysiological readouts to a lesser extent. Furthermore, ample preclinical and clinical evidence indicates that DBS influences neurotransmitter dynamics in PD, particularly the effects of subthalamic nucleus (STN) DBS on striatal dopaminergic and glutamatergic systems; pallidum DBS on striatal dopaminergic and GABAergic systems; pedunculopontine nucleus DBS on cholinergic systems; and STN-DBS on locus coeruleus (LC) noradrenergic system. DBS has additionally been associated with mood-related side effects within brainstem serotoninergic systems in response to STN-DBS. Still, addressing the mechanisms of DBS on neurotransmitters’ dynamics is commonly overlooked due to its practical difficulties in monitoring real-time changes in remote areas. Given that electrical stimulation alters neurotransmitter release in local and remote regions, it eventually exhibits changes in specific neuronal functions. Consequently, such changes lead to further modulation, synthesis, and release of neurotransmitters. This narrative review discusses the main neurotransmitter dynamics in PD and their role in mediating DBS effects from preclinical and clinical data.
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Affiliation(s)
- Faisal Alosaimi
- Department of Neurosurgery, Maastricht University Medical Centre, Maastricht, Netherlands
- Department of Physiology, Faculty of Medicine, King Abdulaziz University, Rabigh, Saudi Arabia
- *Correspondence: Faisal Alosaimi,
| | - Jackson Tyler Boonstra
- Department of Neurosurgery, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Sonny Tan
- Department of Neurosurgery, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Yasin Temel
- Department of Neurosurgery, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Ali Jahanshahi
- Department of Neurosurgery, Maastricht University Medical Centre, Maastricht, Netherlands
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, Netherlands
- Ali Jahanshahi,
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4
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Verkhratsky A, Schousboe A, Zorec R. Preface for the Vladimir Parpura Honorary Issue of Neurochemical Research. Neurochem Res 2021; 46:2507-2511. [PMID: 34405370 DOI: 10.1007/s11064-021-03426-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK. .,Achucarro Center for Neuroscience, IKERBASQUE, 48011, Bilbao, Spain. .,Celica BIOMEDICAL, Tehnološki park 24, 1000, Ljubljana, Slovenia.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Jagtvej 160, 2100, Copenhagen, Denmark
| | - Robert Zorec
- Celica BIOMEDICAL, Tehnološki park 24, 1000, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
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5
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Chiareli RA, Carvalho GA, Marques BL, Mota LS, Oliveira-Lima OC, Gomes RM, Birbrair A, Gomez RS, Simão F, Klempin F, Leist M, Pinto MCX. The Role of Astrocytes in the Neurorepair Process. Front Cell Dev Biol 2021; 9:665795. [PMID: 34113618 PMCID: PMC8186445 DOI: 10.3389/fcell.2021.665795] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/29/2021] [Indexed: 12/17/2022] Open
Abstract
Astrocytes are highly specialized glial cells responsible for trophic and metabolic support of neurons. They are associated to ionic homeostasis, the regulation of cerebral blood flow and metabolism, the modulation of synaptic activity by capturing and recycle of neurotransmitters and maintenance of the blood-brain barrier. During injuries and infections, astrocytes act in cerebral defense through heterogeneous and progressive changes in their gene expression, morphology, proliferative capacity, and function, which is known as reactive astrocytes. Thus, reactive astrocytes release several signaling molecules that modulates and contributes to the defense against injuries and infection in the central nervous system. Therefore, deciphering the complex signaling pathways of reactive astrocytes after brain damage can contribute to the neuroinflammation control and reveal new molecular targets to stimulate neurorepair process. In this review, we present the current knowledge about the role of astrocytes in brain damage and repair, highlighting the cellular and molecular bases involved in synaptogenesis and neurogenesis. In addition, we present new approaches to modulate the astrocytic activity and potentiates the neurorepair process after brain damage.
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Affiliation(s)
| | | | | | - Lennia Soares Mota
- Department of Pharmacology, Federal University of Goias, Goiânia, Brazil
| | | | | | - Alexander Birbrair
- Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Renato Santiago Gomez
- Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Fabrício Simão
- Research Division, Vascular Cell Biology, Joslin Diabetes Center and Harvard Medical School, Boston, MA, United States
| | | | - Marcel Leist
- Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
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6
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Lim D, Semyanov A, Genazzani A, Verkhratsky A. Calcium signaling in neuroglia. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:1-53. [PMID: 34253292 DOI: 10.1016/bs.ircmb.2021.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glial cells exploit calcium (Ca2+) signals to perceive the information about the activity of the nervous tissue and the tissue environment to translate this information into an array of homeostatic, signaling and defensive reactions. Astrocytes, the best studied glial cells, use several Ca2+ signaling generation pathways that include Ca2+ entry through plasma membrane, release from endoplasmic reticulum (ER) and from mitochondria. Activation of metabotropic receptors on the plasma membrane of glial cells is coupled to an enzymatic cascade in which a second messenger, InsP3 is generated thus activating intracellular Ca2+ release channels in the ER endomembrane. Astrocytes also possess store-operated Ca2+ entry and express several ligand-gated Ca2+ channels. In vivo astrocytes generate heterogeneous Ca2+ signals, which are short and frequent in distal processes, but large and relatively rare in soma. In response to neuronal activity intracellular and inter-cellular astrocytic Ca2+ waves can be produced. Astrocytic Ca2+ signals are involved in secretion, they regulate ion transport across cell membranes, and are contributing to cell morphological plasticity. Therefore, astrocytic Ca2+ signals are linked to fundamental functions of the central nervous system ranging from synaptic transmission to behavior. In oligodendrocytes, Ca2+ signals are generated by plasmalemmal Ca2+ influx, or by release from intracellular stores, or by combination of both. Microglial cells exploit Ca2+ permeable ionotropic purinergic receptors and transient receptor potential channels as well as ER Ca2+ release. In this contribution, basic morphology of glial cells, glial Ca2+ signaling toolkit, intracellular Ca2+ signals and Ca2+-regulated functions are discussed with focus on astrocytes.
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Affiliation(s)
- Dmitry Lim
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy.
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Faculty of Biology, Moscow State University, Moscow, Russia; Sechenov First Moscow State Medical University, Moscow, Russia
| | - Armando Genazzani
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy
| | - Alexei Verkhratsky
- Sechenov First Moscow State Medical University, Moscow, Russia; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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7
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Hwang SN, Lee JS, Seo K, Lee H. Astrocytic Regulation of Neural Circuits Underlying Behaviors. Cells 2021; 10:cells10020296. [PMID: 33535587 PMCID: PMC7912785 DOI: 10.3390/cells10020296] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/23/2021] [Accepted: 01/29/2021] [Indexed: 02/07/2023] Open
Abstract
Astrocytes, characterized by a satellite-like morphology, are the most abundant type of glia in the central nervous system. Their main functions have been thought to be limited to providing homeostatic support for neurons, but recent studies have revealed that astrocytes actually actively interact with local neural circuits and play a crucial role in information processing and generating physiological and behavioral responses. Here, we review the emerging roles of astrocytes in many brain regions, particularly by focusing on intracellular changes in astrocytes and their interactions with neurons at the molecular and neural circuit levels.
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Affiliation(s)
- Sun-Nyoung Hwang
- Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
| | - Jae Seung Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
| | - Kain Seo
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
| | - Hyosang Lee
- Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
- Korea Brain Research Institute (KBRI), Daegu 41062, Korea
- Correspondence: ; Tel.: +82-53-785-6147
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8
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Reevaluation of Astrocyte-Neuron Energy Metabolism with Astrocyte Volume Fraction Correction: Impact on Cellular Glucose Oxidation Rates, Glutamate-Glutamine Cycle Energetics, Glycogen Levels and Utilization Rates vs. Exercising Muscle, and Na +/K + Pumping Rates. Neurochem Res 2020; 45:2607-2630. [PMID: 32948935 DOI: 10.1007/s11064-020-03125-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/31/2020] [Accepted: 09/03/2020] [Indexed: 12/22/2022]
Abstract
Accurate quantification of cellular contributions to rates of substrate utilization in resting, activated, and diseased brain is essential for interpretation of data from studies using [18F]fluorodeoxyglucose-positron-emission tomography (FDG-PET) and [13C]glucose/magnetic resonance spectroscopy (MRS). A generally-accepted dogma is that neurons have the highest energy demands of all brain cells, and calculated neuronal rates of glucose oxidation in awake, resting brain accounts for 70-80%, with astrocytes 20-30%. However, these proportions do not take cell type volume fractions into account. To evaluate the conclusion that neuron-astrocyte glucose oxidation rates are similar when adjusted for astrocytic volume fraction (Hertz, Magn Reson Imaging 2011; 29, 1319), the present study analyzed data from 31 studies. On average, astrocytes occupy 6.1, 9.6, and 15% of tissue volume in hippocampus, cerebral cortex, and cerebellum, respectively, and regional astrocytic metabolic rates are adjusted for volume fraction by multiplying by 17.6, 11.4, and 6.8, respectively. After adjustment, astrocytic glucose oxidation rates in resting awake rat brain are 4-10 fold higher than neuronal oxidation rates. Volume-fraction adjustment also increases brain glycogen concentrations and utilization rates to be similar to or exceed exercising muscle. Ion flux calculations to evaluate sodium/potassium homeostasis during neurotransmission are not correct if astrocyte-neuron volume fractions are assumed to be equal. High rates of glucose and glycogen utilization after adjustment for volume fraction indicate that astrocytic energy demands are much greater than recognized, with most of the ATP being used for functions other than glutamate processing in the glutamate-glutamine cycle, challenging the notion that astrocytes 'feed hungry neurons'.
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9
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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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10
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Garofalo S, Picard K, Limatola C, Nadjar A, Pascual O, Tremblay MÈ. Role of Glia in the Regulation of Sleep in Health and Disease. Compr Physiol 2020; 10:687-712. [PMID: 32163207 DOI: 10.1002/cphy.c190022] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sleep is a naturally occurring physiological state that is required to sustain physical and mental health. Traditionally viewed as strictly regulated by top-down control mechanisms, sleep is now known to also originate locally. Glial cells are emerging as important contributors to the regulation of sleep-wake cycles, locally and among dedicated neural circuits. A few pioneering studies revealed that astrocytes and microglia may influence sleep pressure, duration as well as intensity, but the precise involvement of these two glial cells in the regulation of sleep remains to be fully addressed, across contexts of health and disease. In this overview article, we will first summarize the literature pertaining to the role of astrocytes and microglia in the regulation of sleep under normal physiological conditions. Afterward, we will discuss the beneficial and deleterious consequences of glia-mediated neuroinflammation, whether it is acute, or chronic and associated with brain diseases, on the regulation of sleep. Sleep disturbances are a main comorbidity in neurodegenerative diseases, and in several brain diseases that include pain, epilepsy, and cancer. Identifying the relationships between glia-mediated neuroinflammation, sleep-wake rhythm disruption and brain diseases may have important implications for the treatment of several disorders. © 2020 American Physiological Society. Compr Physiol 10:687-712, 2020.
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Affiliation(s)
- Stefano Garofalo
- Department of Physiology and Pharmacology, Sapienza University, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
| | - Katherine Picard
- Nutrition et Neurobiologie Intégrée, UMR 1286, Institut National de la Recherche Agronomique, Bordeaux University, Bordeaux, France.,Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, Québec, Quebec, Canada
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
| | - Agnès Nadjar
- Nutrition et Neurobiologie Intégrée, UMR 1286, Institut National de la Recherche Agronomique, Bordeaux University, Bordeaux, France
| | - Olivier Pascual
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Université Claude Bernard Lyon, Lyon, France
| | - Marie-Ève Tremblay
- Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, Québec, Quebec, Canada.,Départment de médecine moleculaire, Faculté de médecine, Université Laval, Québec, Quebec, Canada
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11
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Pan Y, Monje M. Activity Shapes Neural Circuit Form and Function: A Historical Perspective. J Neurosci 2020; 40:944-954. [PMID: 31996470 PMCID: PMC6988998 DOI: 10.1523/jneurosci.0740-19.2019] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 12/07/2019] [Accepted: 12/10/2019] [Indexed: 12/30/2022] Open
Abstract
The brilliant and often prescient hypotheses of Ramon y Cajal have proven foundational for modern neuroscience, but his statement that "In adult centers the nerve paths are something fixed, ended, immutable … " is an exception that did not stand the test of empirical study. Mechanisms of cellular and circuit-level plasticity continue to shape and reshape many regions of the adult nervous system long after the neurodevelopmental period. Initially focused on neurons alone, the field has followed a meteoric trajectory in understanding of activity-regulated neurodevelopment and ongoing neuroplasticity with an arc toward appreciating neuron-glial interactions and the role that each neural cell type plays in shaping adaptable neural circuity. In this review, as part of a celebration of the 50th anniversary of Society for Neuroscience, we provide a historical perspective, following this arc of inquiry from neuronal to neuron-glial mechanisms by which activity and experience modulate circuit structure and function. The scope of this consideration is broad, and it will not be possible to cover the wealth of knowledge about all aspects of activity-dependent circuit development and plasticity in depth.
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Affiliation(s)
- Yuan Pan
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California 94305
| | - Michelle Monje
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California 94305
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12
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Calcium Signaling in Neurons and Glial Cells: Role of Cav1 channels. Neuroscience 2019; 421:95-111. [DOI: 10.1016/j.neuroscience.2019.09.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/27/2019] [Accepted: 09/30/2019] [Indexed: 11/18/2022]
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13
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Verkhratsky A. Astroglial Calcium Signaling in Aging and Alzheimer's Disease. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035188. [PMID: 31110130 DOI: 10.1101/cshperspect.a035188] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Astrocytes are the homeostatic and protective cells of the central nervous system (CNS). In neurological diseases, astrocytes undergo complex changes, which are subclassified into (1) reactive astrogliosis, an evolutionary conserved defensive rearrangement of cellular phenotype aimed at neuroprotection; (2) pathological remodeling, when astrocytes acquire new features driving pathology; and (3) astrodegeneration, which is manifested by astroglial atrophy and loss of homeostatic functions. In aging brains as well as in the brains affected by Alzheimer's disease (AD), astrocytes acquire both atrophic and reactive phenotypes in a region- and disease-stage-dependent manner. Prevalence of atrophy overreactivity, observed in certain brain regions and in terminal stages of the disease, arguably facilitates the development of neurological deficits. Astrocytes exhibit ionic excitability mediated by changes in intracellular concentration of ions, most importantly of Ca2+ and Na+, with intracellular ion dynamics triggered by the activity of neural networks. AD astrocytes associated with senile plaques demonstrate Ca2+ hyperactivity in the form of aberrant Ca2+ oscillations and pathological long-range Ca2+ waves. Astroglial Ca2+ signaling originating from Ca2+ release from the endoplasmic reticulum is a key factor in initiating astrogliotic response; deficient Ca2+ signaling toolkits observed in entorhinal and prefrontal cortices of AD model animals may account for vulnerability of these regions to the pathology.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom.,Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.,Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
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14
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Identification of cytotoxic markers in methamphetamine treated rat C6 astroglia-like cells. Sci Rep 2019; 9:9412. [PMID: 31253835 PMCID: PMC6599005 DOI: 10.1038/s41598-019-45845-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 06/14/2019] [Indexed: 12/11/2022] Open
Abstract
Methamphetamine (METH) is a powerfully addictive psychostimulant that has a pronounced effect on the central nervous system (CNS). The present study aimed to assess METH toxicity in differentiated C6 astroglia-like cells through biochemical and toxicity markers with acute (1 h) and chronic (48 h) treatments. In the absence of external stimulants, cellular differentiation of neuronal morphology was achieved through reduced serum (2.5%) in the medium. The cells displayed branched neurite-like processes with extensive intercellular connections. Results indicated that acute METH treatment neither altered the cell morphology nor killed the cells, which echoed with lack of consequence on reactive oxygen species (ROS), nitric oxide (NO) or inhibition of any cell cycle phases except induction of cytoplasmic vacuoles. On the other hand, chronic treatment at 1 mM or above destroyed the neurite-like processors and decreased the cell viability that paralleled with increased levels of ROS, lipid peroxidation and lactate, depletion in glutathione (GSH) level and inhibition at G0/G1 phase of cell cycle, leading to apoptosis. Pre-treatment of cells with N-acetyl cysteine (NAC, 2.5 mM for 1 h) followed by METH co-treatment for 48 h rescued the cells completely from toxicity by decreasing ROS through increased GSH. Our results provide evidence that increased ROS and GSH depletion underlie the cytotoxic effects of METH in the cells. Since loss in neurite connections and intracellular changes can lead to psychiatric illnesses in drug users, the evidence that we show in our study suggests that these are also contributing factors for psychiatric-illnesses in METH addicts.
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15
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Wade JJ, Breslin K, Wong-Lin K, Harkin J, Flanagan B, Van Zalinge H, Hall S, Dallas M, Bithell A, Verkhratsky A, McDaid L. Calcium Microdomain Formation at the Perisynaptic Cradle Due to NCX Reversal: A Computational Study. Front Cell Neurosci 2019; 13:185. [PMID: 31133809 PMCID: PMC6513884 DOI: 10.3389/fncel.2019.00185] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 04/12/2019] [Indexed: 01/06/2023] Open
Abstract
It has recently been proposed using a multi-compartmental mathematical model that negatively fixed charged membrane-associated sites constrain the flow of cations in perisynaptic astroglial processes. This restricted movement of ions between the perisynaptic cradle (PsC), principal astroglial processes and the astrocyte soma gives rise to potassium (K+) and sodium (Na+) microdomains at the PsC. The present paper extends the above model to demonstrate that the formation of an Na+ microdomain can reverse the Na+/Ca2+ exchanger (NCX) thus providing an additional source of calcium (Ca2+) at the PsC. Results presented clearly show that reversal of the Na+/Ca2+ exchanger is instigated by a glutamate transporter coupled increase in concentration of cytoplasmic [Na+]i at the PsC, which and instigates Ca2+ influx through the NCX. As the flow of Ca2+ along the astrocyte process and away from the PsC is also constrained by Ca2+ binding proteins, then a Ca2+ microdomain forms at the PsC. The paper also serves to demonstrate that the EAAT, NKA, and NCX represent the minimal requirement necessary and sufficient for the development of a Ca2+ microdomain and that these mechanisms directly link neuronal activity and glutamate release to the formation of localized Na+ and Ca2+ microdomains signals at the PsC. This local source of Ca2+ can provide a previously underexplored form of astroglial Ca2+ signaling.
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Affiliation(s)
- John Joseph Wade
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Kevin Breslin
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - KongFatt Wong-Lin
- Neural Systems and Neurotechnology Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Jim Harkin
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Bronac Flanagan
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
| | - Harm Van Zalinge
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Steve Hall
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Mark Dallas
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Angela Bithell
- Reading School of Pharmacy, University of Reading, Reading, United Kingdom
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Liam McDaid
- Computational Neuroscience and Neural Engineering (CNET) Research Team, Intelligent Systems Research Centre, Ulster University, Derry, United Kingdom
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Multiple Lines of Evidence Indicate That Gliotransmission Does Not Occur under Physiological Conditions. J Neurosci 2019; 38:3-13. [PMID: 29298904 DOI: 10.1523/jneurosci.0016-17.2017] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 09/01/2017] [Accepted: 10/02/2017] [Indexed: 12/22/2022] Open
Abstract
A major controversy persists within the field of glial biology concerning whether or not, under physiological conditions, neuronal activity leads to Ca2+-dependent release of neurotransmitters from astrocytes, a phenomenon known as gliotransmission. Our perspective is that, while we and others can apply techniques to cause gliotransmission, there is considerable evidence gathered using astrocyte-specific and more physiological approaches which suggests that gliotransmission is a pharmacological phenomenon rather than a physiological process. Approaches providing evidence against gliotransmission include stimulation of Gq-GPCRs expressed only in astrocytes, as well as removal of the primary proposed source of astrocyte Ca2+ responsible for gliotransmission. These approaches contrast with those supportive of gliotransmission, which include mechanical stimulation, strong astrocytic depolarization using whole-cell patch-clamp or optogenetics, uncaging Ca2+ or IP3, chelating Ca2+ using BAPTA, and nonspecific bath application of agonists to receptors expressed by a multitude of cell types. These techniques are not subtle and therefore are not supportive of recent suggestions that gliotransmission requires very specific and delicate temporal and spatial requirements. Other evidence, including lack of propagating Ca2+ waves between astrocytes in healthy tissue, lack of expression of vesicular release machinery, and the demise of the d-serine gliotransmission hypothesis, provides additional evidence against gliotransmission. Overall, the data suggest that Ca2+-dependent release of neurotransmitters is the province of neurons, not astrocytes, in the intact brain under physiological conditions.Dual Perspectives Companion Paper: Gliotransmission: Beyond Black-and-White, by Iaroslav Savtchouk and Andrea Volterra.
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Chen X, Feng Y, Huo Y, Tan W. The Interplay of Rogue and Clustered Ryanodine Receptors Regulates Ca2+ Waves in Cardiac Myocytes. Front Physiol 2018; 9:393. [PMID: 29755362 PMCID: PMC5932313 DOI: 10.3389/fphys.2018.00393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 04/03/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- Xudong Chen
- State Key Laboratory of Turbulence and Complex Systems and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Yundi Feng
- State Key Laboratory of Turbulence and Complex Systems and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
| | - Yunlong Huo
- State Key Laboratory of Turbulence and Complex Systems and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
- PKU-HKUST Shenzhen-Hong Kong Institution, Shenzhen, China
- *Correspondence: Yunlong Huo
| | - Wenchang Tan
- State Key Laboratory of Turbulence and Complex Systems and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing, China
- PKU-HKUST Shenzhen-Hong Kong Institution, Shenzhen, China
- Shenzhen Graduate School, Peking University, Shenzhen, China
- Wenchang Tan
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 916] [Impact Index Per Article: 152.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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Berezhnaya E, Bibov M, Komandirov M, Neginskaya M, Rudkovskii M, Uzdensky A. Involvement of MAPK, Akt/GSK-3β and AMPK/mTOR signaling pathways in protection of remote glial cells from axotomy-induced necrosis and apoptosis in the isolated crayfish stretch receptor. Mol Cell Neurosci 2017. [DOI: 10.1016/j.mcn.2017.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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21
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Ding Y, Ling J, Qiao Y, Li Z, Sun Z, Cai J, Guo Y, Wang H. A high-throughput fluorimetric microarray with enhanced fluorescence and suppressed "coffee-ring" effects for the detection of calcium ions in blood. Sci Rep 2016; 6:38602. [PMID: 27917959 PMCID: PMC5137002 DOI: 10.1038/srep38602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/09/2016] [Indexed: 01/29/2023] Open
Abstract
A rapid, ultrasensitive, and high-throughput fluorimetric microarray method has been developed using hydrophobic pattern as the microarray substrate and 3-aminopropyltriethoxysilane-coupled carboxylic acid calcium (APS-CCA) as the fluorescent probes for sensing Ca2+ ions in blood. The hydrophobic pattern of the developed Ca2+ analysis microarray could largely suppress the "coffee-ring" effects to facilitate the better distribution density of testing microspots toward the high-throughput detections, and especially prevent the cross-contamination of the multiple samples between adjacent microspots. Moreover, the use of APS matrix could endow the CCA probe the enhanced environmental stability and fluorescence intensity, which is about 2.3-fold higher than that of free CCA. The interactions between APS-CCA and Ca2+ ions were systematically characterized by UV-vis and fluorescence measurements including microscopy imaging. It was demonstrated that the fluorimetric microarray could display the strong capacity of specifically sensing Ca2+ ions with the minimal interferences from blood backgrounds. Such an APS-CCA-based fluorimetric microarray can allow for the analysis of Ca2+ ions down to 0.0050 mM in blood, promising a highly sensitive and selective detection candidate for Ca2+ ions to be applied in the clinical laboratory.
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Affiliation(s)
- Yanjun Ding
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Jiang Ling
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Yuchun Qiao
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zhengjian Li
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Zongzhao Sun
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
| | - Jifeng Cai
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Yadong Guo
- Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, Hunan, China
| | - Hua Wang
- College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China
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23
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Abstract
Since their discovery in the late nineteenth century, glial cells have taken a backstage role to neurons in our investigations of the nervous system. Yet, in the mammalian brain, glial cells outnumber neurons and comprise 50% of the brain volume. A number of proteins, including important synthetic enzymes, are located almost exclusively in glia, suggesting that glial cells may serve functions beyond providing structural support. Speculations of more active roles for glial cells in brain function began at the turn of the century, at which time it had been suggested that they serve nutritive functions (Golgi, 1885), insulate nerve fibers (Ramon y Cajal, 1909), phagocytose dying neurons (Marinesco, 1896), secrete fac tors (Achucarro, 1915), and remove neurotransmitters (the substances by which one nerve cell excites another) from the synaptic cleft (Lugaro, 1907). Many of these early hypotheses have subsequently gained experimental support; however, our understanding of glial roles in brain function is still limited. The Neuroscientist 1:123-126, 1995
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Abstract
The Na+-Ca 2+ exchanger is a secondary active antiporter found in all excitable cells. This transporter couples transmembrane fluxes of Na+ to opposite fluxes of Ca2+. Under normal conditions, the energy stored in the electrochemical Na+ gradient is used to export Ca 2+ from the cytoplasm, thus contributing to cellular Ca2+ homeostasis, such as termination of Ca2+ transients during synaptic transmission in nerve terminals. The reversible and electrogenic properties of the Na+-Ca2+ exchanger suggest an interesting additional role of controlled Ca2+ entry, e.g., during action potential generation in axons. Moreover, under pathological conditions, such as anoxia/ischemia, the exchanger may function either to help extrude damaging Ca2+ loads entering via other pathways in neurons or mediate Ca2+ overload in axons. Cell geometry will influence the rate and extent of collapse of the Na+ gradient and membrane potential, the two main driving forces acting on the exchanger, which will in turn dictate to what extent and in which direction Ca2+ will be transported. The Na+-Ca2+ exchanger is subject to complex regulatory control by several ions and chemical messengers, and several recently identified isoforms are undoubtedly tailored for specific roles in different regions of the CNS. NEUROSCIENTIST 2:162-171, 1996
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Affiliation(s)
| | - Peter K. Stys
- Neurosciences Loeb Institute Ottawa Civic Hospital Ottawa,
Ontario
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25
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Abstract
Throughout the nervous system, neurons are closely surrounded by glial cells, leaving only a 20-nm wide extracellular space filled with interstitial fluid. Ions, transmitters, hormones, nutrients, and waste products all share this narrow diffusion pathway. Because the interstitial space occupies only a small volume, neuronal activity can lead to appreciable changes in the extracellular concentration of ions, protons, and neurotrans mitters. These changes can affect neuronal activity and are believed to be influenced by glial cells. The proximity of glial processes to synapses and axons make glial cells ideal partners to sequester ions and transmitters released by neurons. The failure of glial cells to perform such essential homeostatic functions can have profound effects, and these homeostatic activities may constitute one way in which glial cells can influence neuronal signaling. In addition, glial cells, which, unlike most neurons, are coupled to each other through gap-junctions, communicate with each other and possibly also with adjacent neurons through prop agated intracellular Ca2+waves. The importance of such interglial signaling is not understood. Additionally, glial cells and neurons mutually modulate their expression of ion channels, most likely through factors re leased into the extracellular space. The range of responses observed in glial cells and their intimate anatomical relationship with neurons suggest a broader role for glia than is currently appreciated. It also emphasizes the importance of a better understanding of glial-neuronal interactions to an understanding of brain function. The Neuroscientist 1:328-337, 1995
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Affiliation(s)
- Harald Sontheimer
- Neurobiology Research Center and Department of Physiology and Biophysics The University of Alabama at Birmingham Birmingham, Alabama
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26
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Logica T, Riviere S, Holubiec MI, Castilla R, Barreto GE, Capani F. Metabolic Changes Following Perinatal Asphyxia: Role of Astrocytes and Their Interaction with Neurons. Front Aging Neurosci 2016; 8:116. [PMID: 27445788 PMCID: PMC4921470 DOI: 10.3389/fnagi.2016.00116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 05/03/2016] [Indexed: 11/13/2022] Open
Abstract
Perinatal Asphyxia (PA) represents an important cause of severe neurological deficits including delayed mental and motor development, epilepsy, major cognitive deficits and blindness. The interaction between neurons, astrocytes and endothelial cells plays a central role coupling energy supply with changes in neuronal activity. Traditionally, experimental research focused on neurons, whereas astrocytes have been more related to the damage mechanisms of PA. Astrocytes carry out a number of functions that are critical to normal nervous system function, including uptake of neurotransmitters, regulation of pH and ion concentrations, and metabolic support for neurons. In this work, we aim to review metabolic neuron-astrocyte interactions with the purpose of encourage further research in this area in the context of PA, which is highly complex and its mechanisms and pathways have not been fully elucidated to this day.
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Affiliation(s)
- Tamara Logica
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Stephanie Riviere
- Laboratorio de Biología Molecular, Facultad de Medicina, Instituto de Investigaciones cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Mariana I Holubiec
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - Rocío Castilla
- Laboratorio de Biología Molecular, Facultad de Medicina, Instituto de Investigaciones cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABA Buenos Aires, Argentina
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá Bogotá, Colombia
| | - Francisco Capani
- Laboratorio de Citoarquitectura y Plasticidad Neuronal, Facultad de Medicina, Instituto de Investigaciones Cardiológicas Prof. Dr. Alberto C. Taquini (ININCA), UBA-CONICET, CABABuenos Aires, Argentina; Departamento de Biología, Universidad Argentina JF KennedyBuenos Aires, Argentina; Investigador Asociado, Universidad Autónoma de ChileSantiago, Chile
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27
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Connexin43 in retinal injury and disease. Prog Retin Eye Res 2016; 51:41-68. [DOI: 10.1016/j.preteyeres.2015.09.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/25/2015] [Accepted: 09/27/2015] [Indexed: 12/26/2022]
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Glutamate and ATP at the Interface Between Signaling and Metabolism in Astroglia: Examples from Pathology. Neurochem Res 2016; 42:19-34. [PMID: 26915104 DOI: 10.1007/s11064-016-1848-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 12/17/2022]
Abstract
Glutamate is the main excitatory transmitter in the brain, while ATP represents the most important energy currency in any living cell. Yet, these chemicals play an important role in both processes, enabling them with dual-acting functions in metabolic and intercellular signaling pathways. Glutamate can fuel ATP production, while ATP can act as a transmitter in intercellular signaling. We discuss the interface between glutamate and ATP in signaling and metabolism of astrocytes. Not only do glutamate and ATP cross each other's paths in physiology of the brain, but they also do so in its pathology. We present the fabric of this process in (patho)physiology through the discussion of synthesis and metabolism of ATP and glutamate in astrocytes as well as by providing a general description of astroglial receptors for these molecules along with the downstream signaling pathways that may be activated. It is astroglial receptors for these dual-acting molecules that could hold a key for medical intervention in pathological conditions. We focus on two examples disclosing the role of activation of astroglial ATP and glutamate receptors in pathology of two kinds of brain tissue, gray matter and white matter, respectively. Interventions at the interface of metabolism and signaling show promise for translational medicine.
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29
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Wioland L, Dupont JL, Doussau F, Gaillard S, Heid F, Isope P, Pauillac S, Popoff MR, Bossu JL, Poulain B. Epsilon toxin from Clostridium perfringens acts on oligodendrocytes without forming pores, and causes demyelination. Cell Microbiol 2014; 17:369-88. [PMID: 25287162 DOI: 10.1111/cmi.12373] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 08/29/2014] [Accepted: 09/29/2014] [Indexed: 12/19/2022]
Abstract
Epsilon toxin (ET) is produced by Clostridium perfringens types B and D and causes severe neurological disorders in animals. ET has been observed binding to white matter, suggesting that it may target oligodendrocytes. In primary cultures containing oligodendrocytes and astrocytes, we found that ET (10(-9) M and 10(-7) M) binds to oligodendrocytes, but not to astrocytes. ET induces an increase in extracellular glutamate, and produces oscillations of intracellular Ca(2+) concentration in oligodendrocytes. These effects occurred without any change in the transmembrane resistance of oligodendrocytes, underlining that ET acts through a pore-independent mechanism. Pharmacological investigations revealed that the Ca(2+) oscillations are caused by the ET-induced rise in extracellular glutamate concentration. Indeed, the blockade of metabotropic glutamate receptors type 1 (mGluR1) prevented ET-induced Ca(2+) signals. Activation of the N-methyl-D-aspartate receptor (NMDA-R) is also involved, but to a lesser extent. Oligodendrocytes are responsible for myelinating neuronal axons. Using organotypic cultures of cerebellar slices, we found that ET induced the demyelination of Purkinje cell axons within 24 h. As this effect was suppressed by antagonizing mGluR1 and NMDA-R, demyelination is therefore caused by the initial ET-induced rise in extracellular glutamate concentration. This study reveals the novel possibility that ET can act on oligodendrocytes, thereby causing demyelination. Moreover, it suggests that for certain cell types such as oligodendrocytes, ET can act without forming pores, namely through the activation of an undefined receptor-mediated pathway.
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Affiliation(s)
- Laetitia Wioland
- Centre National de la Recherche Scientifique Associé à l'Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives UPR3212, 5 rue Blaise Pascal, Strasbourg, cedex F-67084, France
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30
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Sayre NL, Chen Y, Sifuentes M, Stoveken B, Lechleiter JD. Purinergic receptor stimulation decreases ischemic brain damage by energizing astrocyte mitochondria. ADVANCES IN NEUROBIOLOGY 2014; 11:121-50. [PMID: 25236727 DOI: 10.1007/978-3-319-08894-5_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
As a leading cause of death in the world, cerebral ischemic stroke has limited treatment options. The lack of glucose and oxygen after stroke is particularly harmful in the brain because neuronal metabolism accounts for significantly more energy consumption per gram of body weight compared to other organs. Our laboratory has identified mitochondrial metabolism of astrocytes to be a key target for pharmacologic intervention, not only because astrocytes play a central role in regulating brain metabolism, but also because they are essential for neuronal health and support. Here we review current literature pertaining to the pathobiology of stroke, along with the role of astrocytes and metabolism in stroke. We also discuss our research, which has revealed that pharmacologic stimulation of metabotropic P2Y1 receptor signaling in astrocytes can increase mitochondrial energy production and also reduce damage after stroke.
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Affiliation(s)
- Naomi L Sayre
- Department of Cellular and Structural Biology, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
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31
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O'Carroll SJ, Becker DL, Davidson JO, Gunn AJ, Nicholson LFB, Green CR. The use of connexin-based therapeutic approaches to target inflammatory diseases. Methods Mol Biol 2014; 1037:519-46. [PMID: 24029957 DOI: 10.1007/978-1-62703-505-7_31] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Alterations in Connexin43 (Cx43) expression levels have been shown to play a role in inflammatory processes including skin wounding and neuroinflammation. Cx43 protein levels increase following a skin wound and can inhibit wound healing. Increased Cx43 has been observed following stroke, epilepsy, ischemia, optic nerve damage, and spinal cord injury with gap junctional communication and hemichannel opening leading to increased secondary damage via the inflammatory response. Connexin43 modulation has been identified as a potential target for protection and repair in neuroinflammation and skin wound repair. This review describes the use of a Cx43 specific antisense oligonucleotide (Cx43 AsODN) and peptide mimetics of the connexin extracellular loop domain to modulate Cx43 expression and/or function in inflammatory disorders of the skin and central nervous system. An overview of the role of connexin43 in inflammatory conditions, how antisense and peptide have allowed us to elucidate the role of Cx43 in these diseases, create models of diseases to test interventions and their potential for use clinically or in current clinical trials is presented. Antisense oligonucleotides are applied topically and have been used to improve wound healing following skin injury. They have also been used to develop ex vivo models of neuroinflammatory diseases that will allow testing of intervention strategies. The connexin mimetic peptides have shown potential in a number of neuroinflammatory disorders in ex vivo models as well as in vivo when delivered directly to the injury site or when delivered systemically.
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Affiliation(s)
- Simon J O'Carroll
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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32
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Wilkinson NM, Metta G. Capture of fixation by rotational flow; a deterministic hypothesis regarding scaling and stochasticity in fixational eye movements. Front Syst Neurosci 2014; 8:29. [PMID: 24616670 PMCID: PMC3935396 DOI: 10.3389/fnsys.2014.00029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/09/2014] [Indexed: 11/13/2022] Open
Abstract
Visual scan paths exhibit complex, stochastic dynamics. Even during visual fixation, the eye is in constant motion. Fixational drift and tremor are thought to reflect fluctuations in the persistent neural activity of neural integrators in the oculomotor brainstem, which integrate sequences of transient saccadic velocity signals into a short term memory of eye position. Despite intensive research and much progress, the precise mechanisms by which oculomotor posture is maintained remain elusive. Drift exhibits a stochastic statistical profile which has been modeled using random walk formalisms. Tremor is widely dismissed as noise. Here we focus on the dynamical profile of fixational tremor, and argue that tremor may be a signal which usefully reflects the workings of oculomotor postural control. We identify signatures reminiscent of a certain flavor of transient neurodynamics; toric traveling waves which rotate around a central phase singularity. Spiral waves play an organizational role in dynamical systems at many scales throughout nature, though their potential functional role in brain activity remains a matter of educated speculation. Spiral waves have a repertoire of functionally interesting dynamical properties, including persistence, which suggest that they could in theory contribute to persistent neural activity in the oculomotor postural control system. Whilst speculative, the singularity hypothesis of oculomotor postural control implies testable predictions, and could provide the beginnings of an integrated dynamical framework for eye movements across scales.
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Affiliation(s)
| | - Giorgio Metta
- iCub Facility, Fondazione Istituto Italiano di Tecnologia Genova, Italy ; Centre for Robotics and Neural Systems, School of Computing and Mathematics, University of Plymouth Plymouth, UK
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33
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Chen X, Guo L, Kang J, Huo Y, Wang S, Tan W. Calcium waves initiating from the anomalous subdiffusive calcium sparks. J R Soc Interface 2014; 11:20130934. [PMID: 24335558 DOI: 10.1098/rsif.2013.0934] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The objective of the study is to investigate the propagation of Ca(2+) waves in full-width cardiac myocytes and carry out sensitivity analysis to study the effects of various physiological parameters on global Ca(2+) waves. Based on the anomalous subdiffusion of Ca(2+) sparks, a mathematical model was proposed to characterize the Ca(2+) waves. The computed results were in agreement with the experimental measurements using confocal microscopy. This model includes variables of current through the Ca(2+) release unit (CRU; ICRU), duration of current flow through CRU (Topen), Ca(2+) sensitivity parameter (K), the longitudinal and transverse spatial separation of CRUs (lx and ly, where x denotes longitudinal direction (x-axis) and y denotes transverse direction (y-axis)) and Ca(2+) diffusion coefficients (Dx, Dy). The spatio-temporal mechanism of the anomalous Ca(2+) sparks led to results that were different from those based on Fick's law. The major findings were reported as: ICRU affected the dynamic properties of Ca(2+) waves more significantly than Topen; the effect of K on the properties of Ca(2+) waves was negligible; ly affected the amplitude significantly, but lx affected the longitudinal velocity significantly; in turn, the limitation and significance of the study are discussed.
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Affiliation(s)
- Xi Chen
- State Key Laboratory of Turbulence and Complex Systems and Department of Mechanics and Engineering Science, College of Engineering, Peking University, , Beijing 100871, People's Republic of China
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Arne Schousboe, Bachevalier J, Braak H, Heinemann U, Nitsch R, Schröder H, Wetmore C. Structural correlates and cellular mechanisms in entorhinal—hippocampal dysfunction. Hippocampus 2013. [DOI: 10.1002/hipo.1993.4500030732] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Arne Schousboe
- PharmaBiotec Research Center, the Neurobiology Unit, Department of Biological Sciences, Royal Danish School of Pharmacy, Copenhagen, Denmark
| | - Jocelyne Bachevalier
- Medical School, Department of Neurobiology and Anatomy, University of Texas, Houston, Texas, U.S.A
| | - Heiko Braak
- Center of Morphology, Goethe‐University, Frankfurt, Germany
| | - Uwe Heinemann
- Institute of Neurophysiology, University of Köln, Köln, Germany
| | - Robert Nitsch
- Institute of Anatomy, University of Köln, Köln, Germany
| | | | - Cynthia Wetmore
- Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis, Minnesota, U.S.A
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Ghosh A, Wyss MT, Weber B. Somatotopic astrocytic activity in the somatosensory cortex. Glia 2013; 61:601-10. [PMID: 23339077 DOI: 10.1002/glia.22458] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 12/05/2012] [Indexed: 11/11/2022]
Abstract
Astrocytes play a crucial role in maintaining neuronal function and monitoring their activity. According to neuronal activity maps, the body is represented topographically in the somatosensory cortex. In rats, neighboring cortical areas receive forelimb (FL) and hindlimb (HL) sensory inputs. Whether astrocytic activity is also restricted to the cortical area receiving the respective peripheral sensory inputs is not known. Using wide field optical imaging we measured changes in the concentration of astrocytic calcium within the FL and HL sensorimotor cortex in response to peripheral sensory inputs. Mapping the calcium signals upon electrical stimulation of the forepaw and hindpaw we found activity largely restricted to the FL and HL area, respectively. In comparison to neuronal activity the time course of the astrocytic calcium activity was considerably slower. The signal took 6 s to peak after the onset of a 2 Hz and 2 s long electrical stimulation of the hindpaw and 8 s for a 4 s stimulation. The astrocytic signals were delayed relative to cerebral blood flow measured using laser speckle imaging. The intensity of both the astrocytic and neuronal signals in the HL sensorimotor cortex declined with increase in stimulation frequency. Moreover, blocking neuronal input by tetrodotoxin abolished astrocytic calcium signals. We suggest that the topographical representation of the body is not only true for cortical neurons but also for astrocytes. The maps and the frequency-dependent activations reflect strong reciprocal neuroglial communication and provide a new experimental approach to explore the role of astrocytes in health and disease.
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Affiliation(s)
- Arko Ghosh
- Institute of Neuroinformatics, ETH and University of Zurich, Zurich, Switzerland.
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36
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Brazhe A, Mathiesen C, Lauritzen M. Multiscale vision model highlights spontaneous glial calcium waves recorded by 2-photon imaging in brain tissue. Neuroimage 2012; 68:192-202. [PMID: 23219568 DOI: 10.1016/j.neuroimage.2012.11.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 10/26/2012] [Accepted: 11/19/2012] [Indexed: 11/17/2022] Open
Abstract
Intercellular glial calcium waves (GCW) constitute a signaling pathway which can be visualized by fluorescence imaging of cytosolic Ca(2+) changes. Reliable detection of calcium waves in multiphoton imaging data is challenging because of low signal-to-noise ratio. We modified the multiscale vision model (MVM), originally employed to detect faint objects in astronomy data to process stacks of fluorescent images. We demonstrate that the MVM identified and characterized GCWs with much higher sensitivity and detail than pixel thresholding. Origins of GCWs were often associated with prolonged secondary Ca(2+) elevations. The GCWs had variable shapes, and secondary GCWs were observed to bud from the primary, larger GCW. GCWs evaded areas shortly before occupied by a preceding GCW instead circulating around the refractory area. Blood vessels uniquely reshaped GCWs and were associated with secondary GCW events. We conclude that the MVM provides unique possibilities to study spatiotemporally correlated Ca(2+) signaling in brain tissue.
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Affiliation(s)
- Alexey Brazhe
- Department of Biophysics, Faculty of Biology, Moscow State University, 119234 Moscow, Russia.
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37
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Oswald DJ, Lee A, Trinidad M, Chi C, Ren R, Rich CB, Trinkaus-Randall V. Communication between corneal epithelial cells and trigeminal neurons is facilitated by purinergic (P2) and glutamatergic receptors. PLoS One 2012; 7:e44574. [PMID: 22970252 PMCID: PMC3436752 DOI: 10.1371/journal.pone.0044574] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 08/09/2012] [Indexed: 01/15/2023] Open
Abstract
Previously, we demonstrated that nucleotides released upon mechanical injury to corneal epithelium activate purinergic (P2) receptors resulting in mobilization of a Ca2+ wave. However, the tissue is extensively innervated and communication between epithelium and neurons is critical and not well understood. Therefore, we developed a co-culture of primary trigeminal neurons and human corneal limbal epithelial cells. We demonstrated that trigeminal neurons expressed a repertoire of P2Yand P2X receptor transcripts and responded to P2 agonists in a concentration-dependent manner. Mechanical injuries to epithelia in the co-cultures elicited a Ca2+ wave that mobilized to neurons and was attenuated by Apyrase, an ectonucleotidase. To elucidate the role of factors released from each cell type, epithelial and neuronal cells were cultured, injured, and the wound media from one cell type was collected and added to the other cell type. Epithelial wound media generated a rapid Ca2+ mobilization in neuronal cells that was abrogated in the presence of Apyrase, while neuronal wound media elicited a complex response in epithelial cells. The rapid Ca2+ mobilization was detected, which was abrogated with Apyrase, but it was followed by Ca2+ waves that occurred in cell clusters. When neuronal wound media was preincubated with a cocktail of N-methyl-D-aspartate (NMDA) receptor inhibitors, the secondary response in epithelia was diminished. Glutamate was detected in the neuronal wound media and epithelial expression of NMDA receptor subunit transcripts was demonstrated. Our results indicate that corneal epithelia and neurons communicate via purinergic and NMDA receptors that mediate the wound response in a highly orchestrated manner.
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Affiliation(s)
- Duane J Oswald
- Departments of Biochemistry and Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States of America
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38
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Skupin A, Thurley K. Calcium signaling: from single channels to pathways. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:531-51. [PMID: 22453959 DOI: 10.1007/978-94-007-2888-2_24] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ca(2+) is not only one of the most versatile and ubiquitous second messengers but also a well-established representative example of cell signaling. The identification of most key elements involved in Ca(2+) signaling enables a mechanistic and quantitative understanding of this particular pathway. Cellular behavior relies in general on the orchestration of molecular behavior leading to reliable cellular responses that allow for regulation and adaptation. Ca(2+) signaling uses a hierarchical organization to transform single molecule behavior into cell wide signals. We have recently shown experimentally that this organization carries single channel signatures onto the whole cell level and renders Ca(2+) oscillations stochastic. Here, we briefly review the co-evolution of experimental and theoretical studies in Ca(2+) -signaling and show how dynamic bottom-up modeling can be used to address -biological questions and illuminate biological principles of cell signaling.
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Affiliation(s)
- Alexander Skupin
- Luxembourg Centre of Systems Biomedicine, University Luxembourg, Luxembourg.
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Calcium signaling in cerebral vasoregulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:833-58. [PMID: 22453972 DOI: 10.1007/978-94-007-2888-2_37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The tight coupling of regional neurometabolic activity with synaptic activity and regional cerebral blood perfusion constitutes a single functional unit, described generally as a neurovascular unit. This is central to any discussion of haemodynamic response linked to any neuronal activation. In normal as well as in pathologic conditions, neurons, astrocytes and endothelial cells of the vasculature interact to generate the complex activity-induced cerebral haemodynamic responses, with astrocytes not only partaking in the signaling but actually controlling it in many cases. Neurons and astrocytes have highly integrated signaling mechanisms, yet they form two separate networks. Bidirectional neuron-astrocyte interactions are crucial for the function and survival of the central nervous system. The primary purpose of such regulation is the homeostasis of the brain's microenvironment. In the maintenance of such homeostasis, astrocytic calcium response is a crucial variable in determining neurovascular control. Future work will be directed towards resolving the nature and extent of astrocytic calcium-mediated mechanisms for gene transcription, in modelling neurovascular control, and in determining calcium sensitive imaging assays that can capture disease variables.
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Abstract
Increasing evidence suggests that cortical astrocytic function is disrupted in mood disorders and suicide. The fine neuroanatomy of astrocytes, however, remains to be investigated in these psychiatric conditions. In this study, we performed a detailed morphometric analysis of 3D-reconstructed gray and white matter astrocytes in Golgi-impregnated anterior cingulate cortex (ACC) samples from depressed suicides and matched controls. Postmortem ACC samples (BA24) from 10 well-characterized depressed suicides and 10 matched sudden-death controls were obtained from the Quebec Suicide Brain Bank. Golgi-impregnated protoplasmic astrocytes (gray matter, layer VI) and fibrous astrocytes (adjacent white matter) were reconstructed, and their morphometric features were analyzed using the Neurolucida software. For each cell, the soma size as well as the number, length, and branching of processes were determined. The densities of thorny protrusions found along the processes of both astrocytic subtypes were also determined. Protoplasmic astrocytes showed no significant difference between groups for any of the quantified parameters. However, fibrous astrocytes had significantly larger cell bodies, as well as longer, more ramified processes in depressed suicides, with values for these parameters being about twice as high as those measured in controls. These results provide the first evidence of altered cortical astrocytic morphology in mood disorders. The presence of hypertrophic astrocytes in BA24 white matter is consistent with reports suggesting white matter alterations in depression, and provides further support to the neuroinflammatory theory of depression.
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Postnov DE, Postnov DD, Schimansky-Geier L. Self-terminating wave patterns and self-organized pacemakers in a phenomenological model of spreading depression. Brain Res 2011; 1434:200-11. [PMID: 22032875 DOI: 10.1016/j.brainres.2011.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 09/28/2011] [Accepted: 10/03/2011] [Indexed: 11/28/2022]
Abstract
A simple reaction-diffusion model of spreading depression (SD) is presented. Its local dynamics are governed by two activator and two inhibitor variables that provide an extremely simplified description of the mutual interaction between the neurons and extracellular space. This interaction is realized by the substances in the extracellular space that are increasing excitability of the neurons that have released them and are diffusing to the neighboring neurons, thereby spreading this excitation. Typical dynamic patterns of simulated activity are presented. The focus is laid on the case where response of the extracellular medium is relatively fast, and retracting waves, spiral-shaped waves, and autonomous pacemakers are observed, which is in good agreement with experimental observations. The underlying mechanisms are found to be related to switching between the local bi-stable, excitable, and self-sustained dynamics in the simulated medium. This article is part of a Special Issue entitled: Neural Coding.
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Affiliation(s)
- D E Postnov
- Department of Physics, Saratov State University, Astrakhanskaya ul. 83, Saratov 410012, Russia.
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42
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Carballo-Quintás M, Martínez-Silva I, Cadarso-Suárez C, Álvarez-Figueiras M, Ares-Pena F, López-Martín E. A study of neurotoxic biomarkers, c-fos and GFAP after acute exposure to GSM radiation at 900MHz in the picrotoxin model of rat brains. Neurotoxicology 2011; 32:478-94. [DOI: 10.1016/j.neuro.2011.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 04/08/2011] [Accepted: 04/10/2011] [Indexed: 10/18/2022]
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Palygin O, Lalo U, Verkhratsky A, Pankratov Y. Ionotropic NMDA and P2X1/5 receptors mediate synaptically induced Ca2+ signalling in cortical astrocytes. Cell Calcium 2011; 48:225-31. [PMID: 20926134 DOI: 10.1016/j.ceca.2010.09.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 09/05/2010] [Accepted: 09/07/2010] [Indexed: 10/19/2022]
Abstract
Local, global and propagating calcium (Ca(2+)) signals provide the substrate for glial excitability. Here we analyse Ca(2+) permeability of NMDA and P2X(1/5) receptors expressed in cortical astrocytes and provide evidence that activation of these receptors trigger astroglial Ca(2+) signals when stimulated by either endogenous agonists or by synaptic release of neurotransmitters. The Ca(2+) permeability of the ionotropic receptors was determined by reversal potential shift analysis; the permeability ratio P(Ca)/P(K) was 3.1 for NMDA receptors and 2.2 for P2X(1/5) receptors. Selective stimulation of ionotropic receptors (with NMDA and α,β-methyleneATP) in freshly isolated cortical astrocytes induced ion currents associated with transient increases in cytosolic Ca(2+) concentration ([Ca(2+)](i)). Stimulation of neuronal afferents in cortical slices triggered glial synaptic currents and [Ca(2+)](i) responses, which were partially blocked by selective antagonists of NMDA (D-AP5 and UBP141) and P2X(1/5) (NF449) receptors. We conclude that ionotropic receptors contribute to astroglial Ca(2+) signalling and may provide a specific mechanism for fast neuronal-glial signalling at the synaptic level.
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Affiliation(s)
- Oleg Palygin
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
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44
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Yoon JJ, Green CR, O’Carroll SJ, Nicholson LF. Dose-dependent protective effect of connexin43 mimetic peptide against neurodegeneration in an ex vivo model of epileptiform lesion. Epilepsy Res 2010; 92:153-62. [DOI: 10.1016/j.eplepsyres.2010.08.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 08/23/2010] [Accepted: 08/24/2010] [Indexed: 11/30/2022]
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45
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Yoon JJ, Nicholson LFB, Feng SX, Vis JC, Green CR. A novel method of organotypic brain slice culture using connexin-specific antisense oligodeoxynucleotides to improve neuronal survival. Brain Res 2010; 1353:194-203. [PMID: 20624376 DOI: 10.1016/j.brainres.2010.07.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Revised: 06/28/2010] [Accepted: 07/05/2010] [Indexed: 11/19/2022]
Abstract
Organotypic slice cultures obtained from immature brain tissue represent a well-established model system for neuroscience research. Current culture methods, however, do not allow long-term culture of mature brain slices. Slice cultures from mature animals would provide an in vitro experimental environment suitable for investigation of neuropathologies, which in human, predominate in aged individuals. We hypothesized that damage, incurred by slicing of the brain, is propagated through intercellular connexin43 (Cx43) gap junction channels and that this damage is not easily repaired in mature central nervous system (CNS) tissue that lacks the pluripotency of immature tissue. We investigated the role of Cx43 gap junctions in long-term survival of mature brain tissue using antisense oligodeoxynucleotide (AsODN) technology. The application of Cx43 AsODN immediately after slicing of the mature brain led to a significant but transient knockdown of Cx43 protein. This treatment was associated with the long-term survival of hippocampal neurons with normal morphology within whole brain slices taken from 14 and 40-day-old adult rats.
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Affiliation(s)
- Jinny Jung Yoon
- Department of Ophthalmology, University of Auckland, New Zealand.
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46
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Witcher MR, Park YD, Lee MR, Sharma S, Harris KM, Kirov SA. Three-dimensional relationships between perisynaptic astroglia and human hippocampal synapses. Glia 2010; 58:572-87. [PMID: 19908288 DOI: 10.1002/glia.20946] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Perisynaptic astroglia are critical for normal synaptic development and function. Little is known, however, about perisynaptic astroglia in the human hippocampus. When mesial temporal lobe epilepsy (MTLE) is refractory to medication, surgical removal is required for seizure quiescence. To investigate perisynaptic astroglia in human hippocampus, we recovered slices for several hours in vitro from three surgical specimens and then quickly fixed them to achieve high-quality ultrastructure. Histological samples from each case were found to have mesial temporal sclerosis with Blumcke Type 1a (mild, moderate) or 1b (severe) pathology. Quantitative analysis through serial section transmission electron microscopy in CA1 stratum radiatum revealed more synapses in the mild (10/10 microm(3)) than the moderate (5/10 microm(3)) or severe (1/10 microm(3)) cases. Normal spines occurred in mild and moderate cases, but a few multisynaptic spines were all that remained in the severe case. Like adult rat hippocampus, perisynaptic astroglial processes were preferentially associated with larger synapses in the mild and moderate cases, but rarely penetrated the cluster of axonal boutons surrounding multisynaptic spines. Synapse perimeters were only partially surrounded by astroglial processes such that all synapses had some access to substances in the extracellular space, similar to adult rat hippocampus. Junctions between astroglial processes were observed more frequently in moderate than mild case, but were obscured by densely packed intermediate filaments in astroglial processes of the severe case. These findings suggest that perisynaptic astroglial processes associate with synapses in human hippocampus in a manner similar to model systems and are disrupted by severe MTLE pathology.
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Fanelli A, Esposti F, Ripamonti M, Signorini MG. Temporal and spatial analysis of astrocyte calcium waves. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:6038-41. [PMID: 19964887 DOI: 10.1109/iembs.2009.5334534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the last decade new ideas were born about the temporal and spatial dynamics of intercellular calcium waves in astrocytes. In this paper we introduce a new approach to analyze the ways in which astrocytes communicate in cultures. We present a method to describe the spatial propagation of Ca(2+) waves in vitro and a technique to compare the activity of different cells in vivo and in vitro under different stimulation conditions. The proposed method resulted to be an interesting way to distinguish different astrocyte clusters, which can be related to the communication characteristics in the network.
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Affiliation(s)
- A Fanelli
- Politecnico di Milano, Dipartimento di Bioingegneria, Milano, Italy.
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48
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Kawai T, Abe H, Wakabayashi KI, Oka Y. Calcium oscillations in the olfactory nonsensory cells of the goldfish, Carassius auratus. Biochim Biophys Acta Gen Subj 2009; 1790:1681-8. [PMID: 19800938 DOI: 10.1016/j.bbagen.2009.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 09/02/2009] [Accepted: 09/28/2009] [Indexed: 11/17/2022]
Abstract
BACKGROUND The olfactory nonsensory cells contribute to the maintenance of normal functions of the olfactory epithelium (OE). Specifically, the ciliated nonsensory cells of teleosts play important roles in the odorant detection by OE in aqueous environment. Their cilia show strong beating activities and cause water flow at the OE surface, making the detection of odorants by OE more efficient. Because intracellular Ca2+ level has been reported to play an important role in ciliary beating, the ciliary beating activity may be regulated by intracellular Ca2+ dynamics of these ciliated nonsensory cells. METHODS We performed Ca2+ imaging experiments to analyze the Ca2+ dynamics in acutely dissociated OE cells of the goldfish. Furthermore, we examined the contribution of the Ca2+ dynamics to the ciliary beating frequency (CBF) at the surface of the intact OE. RESULTS Olfactory nonsensory cells showed both spontaneous intracellular Ca2+ oscillations and propagating intercellular Ca2+ waves. Application of 2-aminoethoxydiphenylborate (2-APB), which antagonizes IP3-induced Ca2+ release from intracellular stores suppressed these Ca2+ oscillations. Furthermore, 2-APB application to the intact OE lamellae resulted in the decrease of CBF at the surface of the OE. CONCLUSIONS These results indicate that spontaneous intracellular calcium oscillations persistently up-regulate the ciliary beating at the surface of the OE in teleosts. GENERAL SIGNIFICANCE Ciliary beating activity at the surface of OE can be regulated by the Ca2+ dynamics of olfactory nonsensory cells. Because this ciliary movement causes inflow of external fluid into the nostril, this regulation is suggested to influence the efficiency of odorant detection by OE.
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Affiliation(s)
- Takafumi Kawai
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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49
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Mann ZF, Duchen MR, Gale JE. Mitochondria modulate the spatio-temporal properties of intra- and intercellular Ca2+ signals in cochlear supporting cells. Cell Calcium 2009; 46:136-46. [PMID: 19631380 DOI: 10.1016/j.ceca.2009.06.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 06/12/2009] [Accepted: 06/28/2009] [Indexed: 10/20/2022]
Abstract
In the cochlea, cell damage triggers intercellular Ca2+ waves that propagate through the glial-like supporting cells that surround receptor hair cells. These Ca2+ waves are thought to convey information about sensory hair cell-damage to the surrounding supporting cells within the cochlear epithelium. Mitochondria are key regulators of cytoplasmic Ca2+ concentration ([Ca2+](cyt)), and yet little is known about their role during the propagation of such intercellular Ca2+ signalling. Using neonatal rat cochlear explants and fluorescence imaging techniques, we explore how mitochondria modulate supporting cell [Ca2+](cyt) signals that are triggered by ATP or by hair cell damage. ATP application (0.1-50 microM) caused a dose dependent increase in [Ca2+](cyt) which was accompanied by an increase in mitochondrial calcium. Blocking mitochondrial Ca2+ uptake by dissipating the mitochondrial membrane potential using CCCP and oligomycin or using Ru360, an inhibitor of the mitochondrial Ca2+ uniporter, enhanced the peak amplitude and duration of ATP-induced [Ca2+](cyt) transients. In the presence of Ru360, the mean propagation velocity, amplitude and extent of spread of damage-induced intercellular Ca2+ waves was significantly increased. Thus, mitochondria function as spatial Ca2+ buffers during agonist-evoked [Ca2+](cyt) signalling in cochlear supporting cells and play a significant role in regulating the spatio-temporal properties of intercellular Ca2+ waves.
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Affiliation(s)
- Zoë F Mann
- UCL Ear Institute, 332 Gray's Inn Road, London WC1X 8EE, UK; Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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50
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Hegg CC, Irwin M, Lucero MT. Calcium store-mediated signaling in sustentacular cells of the mouse olfactory epithelium. Glia 2009; 57:634-44. [PMID: 18942758 DOI: 10.1002/glia.20792] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sustentacular cells have structural features that allude to functions of secretion, absorption, phagocytosis, maintenance of extracellular ionic gradients, metabolism of noxious chemicals, and regulation of cell turnover. We present data detailing their dynamic activity. We show, using a mouse olfactory epithelium slice model, that sustentacular cells are capable of generating two types of calcium signals: intercellular calcium waves where elevations in intracellular calcium propagate between neighboring cells, and intracellular calcium oscillations consisting of repetitive elevations in intracellular calcium confined to single cells. Sustentacular cells exhibited rapid, robust increases in intracellular calcium in response to G-protein coupled muscarinic and purinergic receptor stimulation. In a subpopulation of sustentacular cells, oscillatory calcium transients were evoked. We pharmacologically characterized the properties of purinergic-evoked increases in intracellular calcium. Calcium transients were elicited by release from intracellular stores and were not dependent on extracellular calcium. BAPTA-AM, a cytosolic calcium chelator, and cyclopiazonic acid, an endoplasmic reticulum Ca(2+)-ATPase inhibitor irreversibly blocked the purinergic-induced calcium transient. Phospholipase C antagonist U73122 inhibited the purinergic-evoked calcium transient. 2-Aminoethoxydiphenyl borate, an inositol-1,4,5-trisphosphate (IP(3)) receptor antagonist, and the ryanodine receptor (RyR) antagonists tetracaine and ryanodine, inhibited the UTP-induced calcium transients. Collectively, these data suggest that activation of the phospholipase C pathway, IP(3)-mediated calcium release, and subsequent calcium-induced-calcium release is involved in ATP-elicited increases in intracellular calcium. Our findings indicate that sustentacular cells are not static support cells, and, like glia in the central nervous system, have complex calcium signaling.
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Affiliation(s)
- Colleen Cosgrove Hegg
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA.
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