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Astrocytes in the pathophysiology of neuroinfection. Essays Biochem 2023; 67:131-145. [PMID: 36562155 DOI: 10.1042/ebc20220082] [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: 09/07/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 12/24/2022]
Abstract
Key homeostasis providing cells in the central nervous system (CNS) are astrocytes, which belong to the class of cells known as atroglia, a highly heterogeneous type of neuroglia and a prominent element of the brain defence. Diseases evolve due to altered homeostatic state, associated with pathology-induced astroglia remodelling represented by reactive astrocytes, astroglial atrophy and astrodegeneration. These features are hallmarks of most infectious insults, mediated by bacteria, protozoa and viruses; they are also prominent in the systemic infection. The COVID-19 pandemic revived the focus into neurotropic viruses such as SARS-CoV2 (Coronaviridae) but also the Flaviviridae viruses including tick-borne encephalitis (TBEV) and Zika virus (ZIKV) causing the epidemic in South America prior to COVID-19. Astrocytes provide a key response to neurotropic infections in the CNS. Astrocytes form a parenchymal part of the blood-brain barrier, the site of virus entry into the CNS. Astrocytes exhibit aerobic glycolysis, a form of metabolism characteristic of highly morphologically plastic cells, like cancer cells, hence a suitable milieu for multiplication of infectious agent, including viral particles. However, why the protection afforded by astrocytes fails in some circumstances is an open question to be studied in the future.
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2
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Salinas-Birt A, Zhu X, Lim EY, Cruz Santory AJ, Ye L, Paukert M. Constraints of vigilance-dependent noradrenergic signaling to mouse cerebellar Bergmann glia. Glia 2023; 71:1451-1465. [PMID: 36790089 PMCID: PMC10082684 DOI: 10.1002/glia.24350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 01/25/2023] [Accepted: 01/25/2023] [Indexed: 02/16/2023]
Abstract
Behavioral state plays an important role in determining astroglia Ca2+ signaling. In particular, locomotion-mediated elevated vigilance has been found to trigger norepinephrine-dependent whole cell Ca2+ elevations in astroglia throughout the brain. For cerebellar Bergmann glia it has recently been found that locomotion-induced transient Ca2+ elevations depend on their α1A -adrenergic receptors. With increasing availability and implementation of locomotion as behavioral parameter it becomes important to understand the constraints of noradrenergic signaling to astroglia. Here we evaluated the effect of speed, duration and interval of locomotion on Ca2+ signals in Bergmann glia as well as cerebellar noradrenergic axon terminals. We found almost no dependence on locomotion speed, but following the initial Ca2+ transient prolonged locomotion events revealed a steady-state Ca2+ elevation. Comparison of time course and recovery of transient Bergmann glia and noradrenergic terminal Ca2+ dynamics suggested that noradrenergic terminal Ca2+ activity determines Bergmann glia Ca2+ activation and does not require noradrenergic receptor desensitization to account for attenuation during prolonged locomotion. Further, analyzing the correlation among Ca2+ dynamics within regions within the field of observation we found that coordinated activity among noradrenergic terminals accounts for fluctuations of steady-state Bergmann glia Ca2+ activity. Together, our findings will help to better understand astroglia Ca2+ dynamics during less controlled awake behavior and may guide the identification of behavioral contexts preferably dependent on astroglia Ca2+ signaling.
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Affiliation(s)
- Angelica Salinas-Birt
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Xiangyu Zhu
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Eunice Y Lim
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Aryana J Cruz Santory
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Liang Ye
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Martin Paukert
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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3
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Astroglial Serotonin Receptors as the Central Target of Classic Antidepressants. ADVANCES IN NEUROBIOLOGY 2021; 26:317-347. [PMID: 34888840 DOI: 10.1007/978-3-030-77375-5_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Major depressive disorder (MDD) presents multiple clinical phenotypes and has complex underlying pathological mechanisms. Existing theories cannot completely explain the pathophysiological mechanism(s) of MDD, while the pharmacology of current antidepressants is far from being fully understood. Astrocytes, the homeostatic and defensive cells of the central nervous system, contribute to shaping behaviors, and regulating mood and emotions. A detailed introduction on the role of astrocytes in depressive disorders is thus required, to which this chapter is dedicated. We also focus on the interactions between classic antidepressants and serotonin receptors, overview the role of astrocytes in the pharmacological mechanisms of various antidepressants, and present astrocytes as targets for the treatment of bipolar disorder. We provide a foundation of knowledge on the role of astrocytes in depressive disorders and astroglial 5-HT2B receptors as targets for selective serotonin reuptake inhibitors in vivo and in vitro.
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Verkhratsky A, Parpura V, Li B, Scuderi C. Astrocytes: The Housekeepers and Guardians of the CNS. ADVANCES IN NEUROBIOLOGY 2021; 26:21-53. [PMID: 34888829 DOI: 10.1007/978-3-030-77375-5_2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Astroglia are a diverse group of cells in the central nervous system. They are of the ectodermal, neuroepithelial origin and vary in morphology and function, yet, they can be collectively defined as cells having principle function to maintain homeostasis of the central nervous system at all levels of organisation, including homeostasis of ions, pH and neurotransmitters; supplying neurones with metabolic substrates; supporting oligodendrocytes and axons; regulating synaptogenesis, neurogenesis, and formation and maintenance of the blood-brain barrier; contributing to operation of the glymphatic system; and regulation of systemic homeostasis being central chemosensors for oxygen, CO2 and Na+. Their basic physiological features show a lack of electrical excitability (inapt to produce action potentials), but display instead a rather active excitability based on variations in cytosolic concentrations of Ca2+ and Na+. It is expression of neurotransmitter receptors, pumps and transporters at their plasmalemma, along with transports on the endoplasmic reticulum and mitochondria that exquisitely regulate the cytosolic levels of these ions, the fluctuation of which underlies most, if not all, astroglial homeostatic functions.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Baoman Li
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
| | - Caterina Scuderi
- Department of Physiology and Pharmacology "Vittorio Erspamer", SAPIENZA University of Rome, Rome, Italy
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5
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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: 31] [Impact Index Per Article: 10.3] [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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Verkhratsky A, Semyanov A, Zorec R. Physiology of Astroglial Excitability. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa016. [PMID: 35330636 PMCID: PMC8788756 DOI: 10.1093/function/zqaa016] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/29/2020] [Accepted: 09/03/2020] [Indexed: 01/06/2023]
Abstract
Classic physiology divides all neural cells into excitable neurons and nonexcitable neuroglia. Neuroglial cells, chiefly responsible for homeostasis and defense of the nervous tissue, coordinate their complex homeostatic responses with neuronal activity. This coordination reflects a specific form of glial excitability mediated by complex changes in intracellular concentration of ions and second messengers organized in both space and time. Astrocytes are equipped with multiple molecular cascades, which are central for regulating homeostasis of neurotransmitters, ionostasis, synaptic connectivity, and metabolic support of the central nervous system. Astrocytes are further provisioned with multiple receptors for neurotransmitters and neurohormones, which upon activation trigger intracellular signals mediated by Ca2+, Na+, and cyclic AMP. Calcium signals have distinct organization and underlying mechanisms in different astrocytic compartments thus allowing complex spatiotemporal signaling. Signals mediated by fluctuations in cytosolic Na+ are instrumental for coordination of Na+ dependent astrocytic transporters with tissue state and homeostatic demands. Astroglial ionic excitability may also involve K+, H+, and Cl-. The cyclic AMP signalling system is, in comparison to ions, much slower in targeting astroglial effector mechanisms. This evidence review summarizes the concept of astroglial intracellular excitability.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK,Achucarro Center for Neuroscience, Ikerbasque, 48011 Bilbao, Spain,Address correspondence to A.V. (e-mail: )
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,Faculty of Biology, Moscow State University, Moscow, Russia,Sechenov First Moscow State Medical University, Moscow, Russia
| | - Robert Zorec
- Celica Biomedical, Ljubljana 1000, Slovenia,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
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Rizzi A, Saccia M, Benagiano V. Is the Cerebellum Involved in the Nervous Control of the Immune System Function? Endocr Metab Immune Disord Drug Targets 2019; 20:546-557. [PMID: 31729296 DOI: 10.2174/1871530319666191115144105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/30/2019] [Accepted: 10/10/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND According to the views of psychoneuroendocrinoimmunology, many interactions exist between nervous, endocrine and immune system the purpose of which is to achieve adaptive measures restoring an internal equilibrium (homeostasis) following stress conditions. The center where these interactions converge is the hypothalamus. This is a center of the autonomic nervous system that controls the visceral systems, including the immune system, through both the nervous and neuroendocrine mechanisms. The nervous mechanisms are based on nervous circuits that bidirectionally connect hypothalamic neurons and neurons of the sympathetic and parasympathetic system; the neuroendocrine mechanisms are based on the release by neurosecretory hypothalamic neurons of hormones that target the endocrine cells and on the feedback effects of the hormones secreted by these endocrine cells on the same hypothalamic neurons. Moreover, the hypothalamus is an important subcortical center of the limbic system that controls through nervous and neuroendocrine mechanisms the areas of the cerebral cortex where the psychic functions controlling mood, emotions, anxiety and instinctive behaviors take place. Accordingly, various studies conducted in the last decades have indicated that hypothalamic diseases may be associated with immune and/or psychic disorders. OBJECTIVE Various researches have reported that the hypothalamus is controlled by the cerebellum through a feedback nervous circuit, namely the hypothalamocerebellar circuit, which bi-directionally connects regions of the hypothalamus, including the immunoregulatory ones, and related regions of the cerebellum. An objective of the present review was to analyze the anatomical bases of the nervous and neuroendocrine mechanisms for the control of the immune system and, in particular, of the interaction between hypothalamus and cerebellum to achieve the immunoregulatory function. CONCLUSION Since the hypothalamus represents the link through which the immune functions may influence the psychic functions and vice versa, the cerebellum, controlling several regions of the hypothalamus, could be considered as a primary player in the regulation of the multiple functional interactions postulated by psychoneuroendocrinoimmunology.
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Affiliation(s)
- Anna Rizzi
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs, University of Bari, Policlinico, Piazza Giulio Cesare, 70124 Bari, Italy
| | - Matteo Saccia
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs, University of Bari, Policlinico, Piazza Giulio Cesare, 70124 Bari, Italy
| | - Vincenzo Benagiano
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs, University of Bari, Policlinico, Piazza Giulio Cesare, 70124 Bari, Italy
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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9
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Verkhratsky A, Chvátal A. NMDA Receptors in Astrocytes. Neurochem Res 2019; 45:122-133. [DOI: 10.1007/s11064-019-02750-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 01/22/2019] [Accepted: 02/05/2019] [Indexed: 12/12/2022]
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10
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Rosas-Hernández R, Bastián Y, Juárez Tello A, Ramírez-Saíto Á, Escobar García DM, Pozos-Guillén A, Mendez JA. AMPA receptors modulate the reorganization of F-actin in Bergmann glia cells through the activation of RhoA. J Neurochem 2019; 149:242-254. [PMID: 30589940 DOI: 10.1111/jnc.14658] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 01/23/2023]
Abstract
Alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid glutamate receptors have been shown to modulate the morphology of the lamelar processes of Bergmann glia cells in the molecular layer of the cerebellum. Here we suggest that reorganization of F-actin may underlay the changes in the morphology of the lamelar processes. Using the fluorescent staining of F-actin with Phalloidin and the quantification of RhoA activation through immunoprecipitation or pull-down assays, we show that RhoA is activated after stimulation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors and leads to the reorganization of the actin cytoskeleton of Bergmann fibers. This reorganization of the actin cytoskeleton is reflected in the form of an increase in the intensity of the F-actin staining as well as in the loss of the number of Bergmann fibers stained with Phalloidin. Moreover, using a pharmacological approach, we show that activation of RhoA and the change in the intensity of the F-actin staining depends on the activation of PI3-K, focal adhesion kinase, and protein kinase C, whereas changes in the number of Bergmann fibers depend on external calcium in a RhoA independent manner. Our findings show that glutamate may induce a form of structural plasticity in Bergmann glia cells through the reorganization of the actin cytoskeleton. This may have implications in the way the synaptic transmission is processed in the cerebellum.
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Affiliation(s)
| | - Yadira Bastián
- Unidad de Investigación Biomédica, IMSS, Zacatecas, México
| | - Andrea Juárez Tello
- Laboratory of Molecular Biophysics, Institute of Physics, San Luis Potosi, Mexico
| | | | - Diana María Escobar García
- Laboratory of Basic Sciences, Faculty of Stomatology, Universidad Autónoma de San Luis Potosí, San Luis Potosi, Mexico
| | - Amaury Pozos-Guillén
- Laboratory of Basic Sciences, Faculty of Stomatology, Universidad Autónoma de San Luis Potosí, San Luis Potosi, Mexico
| | - J Alfredo Mendez
- Laboratory of Molecular Biophysics, Institute of Physics, San Luis Potosi, Mexico
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11
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Verkhratsky A, Parpura V, Rodriguez-Arellano JJ, Zorec R. Astroglia in Alzheimer's Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:273-324. [PMID: 31583592 DOI: 10.1007/978-981-13-9913-8_11] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's disease is the most common cause of dementia. Cellular changes in the brains of the patients suffering from Alzheimer's disease occur well in advance of the clinical symptoms. At the cellular level, the most dramatic is a demise of neurones. As astroglial cells carry out homeostatic functions of the brain, it is certain that these cells are at least in part a cause of Alzheimer's disease. Historically, Alois Alzheimer himself has recognised this at the dawn of the disease description. However, the role of astroglia in this disease has been understudied. In this chapter, we summarise the various aspects of glial contribution to this disease and outline the potential of using these cells in prevention (exercise and environmental enrichment) and intervention of this devastating disease.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA.,University of Rijeka, Rijeka, Croatia
| | - Jose Julio Rodriguez-Arellano
- BioCruces Health Research Institute, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.,Department of Neuroscience, The University of the Basque Country UPV/EHU, Plaza de Cruces 12, 48903, Barakaldo, Bizkaia, Spain
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica BIOMEDICAL, Ljubljana, Slovenia
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12
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Zorec R, Županc TA, Verkhratsky A. Astrogliopathology in the infectious insults of the brain. Neurosci Lett 2018; 689:56-62. [PMID: 30096375 DOI: 10.1016/j.neulet.2018.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 08/03/2018] [Accepted: 08/04/2018] [Indexed: 12/28/2022]
Abstract
Astroglia, a heterogeneous type of neuroglia, play key homeostatic functions in the central nervous system (CNS) and represent an important defence system. Impaired homeostatic capacity of astrocytes manifests in diseases and this is mirrored in various astrocyte-based pathological features including reactive astrogliosis, astrodegeneration with astroglial atrophy and pathological remodelling of astrocytes. All of these manifestations are most prominently associated with infectious insults, mediated by bacteria, protozoa and viruses. Here we focus onto neurotropic viruses such as tick-borne encephalitis (TBEV) and Zika virus (ZIKV), both belonging to Flaviviridae and both causing severe neurological impairments. We argue that astrocytes provide a route through which neurotropic infectious agents attack the CNS, since they are anatomically associated with the blood-brain barrier and exhibit aerobic glycolysis, a metabolic specialisation of highly morphologically dynamic cells, which may provide a suitable metabolic milieu for proliferation of infectious agents, including viral bodies.
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Affiliation(s)
- Robert Zorec
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000, Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia
| | - Tatjana Avšič Županc
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
| | - Alexei Verkhratsky
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000, Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
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Leanza G, Gulino R, Zorec R. Noradrenergic Hypothesis Linking Neurodegeneration-Based Cognitive Decline and Astroglia. Front Mol Neurosci 2018; 11:254. [PMID: 30100866 PMCID: PMC6072880 DOI: 10.3389/fnmol.2018.00254] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/05/2018] [Indexed: 12/31/2022] Open
Abstract
In the past, manipulation of the cholinergic system was seen as the most likely therapeutic for neurodegeneration-based cognitive decline in Alzheimer's disease (AD) (Whitehouse et al., 1982). However, targeting the noradrenergic system also seems a promising strategy, since more recent studies revealed that in post-mortem tissue from patients with AD and other neurodegenerative disorders there is a robust correlation between cognitive decline and loss of neurons from the Locus coeruleus (LC), a system with diffuse noradrenaline (NA) innervation in the central nervous system (CNS). Therefore, the hypothesis has been considered that increasing NA signaling in the CNS will prevent, or at least halt the progression of neurodegeneration and cognitive decline. A hallmark of the age- and neurodegeneration-related cognitive decline is reduced neurogenesis. We here discuss noradrenergic dysfunction in AD-related cognitive decline in humans and its potential involvement in AD pathology and disease progression. We also focus on animal models to allow the validation of the noradrenergic hypothesis of AD, including those based upon the immunotoxin-mediated ablation of LC based on saporin, a protein synthesis interfering agent, which offers selective and graded demise of LC neurons, Finally, we address how astrocytes, an abundant and functionally heterogeneous cell type of neuroglia maintaining homeostasis, may participate in the regulation of neurogenesis, a new strategy for preventing LC neuron loss.
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Affiliation(s)
- Giampiero Leanza
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
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14
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Zorec R, Parpura V, Verkhratsky A. Preventing neurodegeneration by adrenergic astroglial excitation. FEBS J 2018; 285:3645-3656. [PMID: 29630772 DOI: 10.1111/febs.14456] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/17/2018] [Accepted: 03/28/2018] [Indexed: 01/22/2023]
Abstract
Impairment of the main noradrenergic nucleus of the human brain, the locus coeruleus (LC), which has been discovered in 1784, represents one of defining factors of neurodegenerative diseases progression. Projections of LC neurons release noradrenaline/norepinephrine (NA), which stimulates astrocytes, homeostatic neuroglial cells enriched with adrenergic receptors. There is a direct correlation between the reduction in noradrenergic innervations and cognitive decline associated with ageing and neurodegenerative diseases. It is, therefore, hypothesized that the resilience of LC neurons to degeneration influences the neural reserve that in turn determines cognitive decline. Deficits in the noradrenergic innervation of the brain might be reversed or restrained by increasing the activity of existing LC neurons, transplanting noradrenergic neurons, and/or using drugs that mimic the activity of NA on astroglia. Here, these strategies are discussed with the aim to understand how astrocytes integrate neuronal network activity in the brain information processing in health and disease.
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Affiliation(s)
- Robert Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, Civitan International Research Center and Center for Glial Biology in Medicine, Evelyn F. McKnight Brain Institute, Atomic Force Microscopy & Nanotechnology Laboratories, University of Alabama, Birmingham, AL, USA
| | - Alexei Verkhratsky
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, University of Ljubljana, Slovenia.,Celica, BIOMEDICAL, Ljubljana, Slovenia.,Faculty of Biology, Medicine and Health, The University of Manchester, UK.,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.,Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain
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15
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Abstract
Introduction: Astroglia represent the main cellular homeostatic system of the central nervous system (CNS). Astrocytes are intimately involved in regulation and maintenance of neurotransmission by regulating neurotransmitters removal and turnover and by supplying neurons with neurotransmitters precursors. Astroglial cells are fundamental elements of monoaminergic transmission in the brain and in the spinal cord. Astrocytes receive monoaminergic inputs and control catabolism of monoamines through dedicated transporters and intracellular enzymatic pathways.Areas covered: Astroglial cells express serotonergic receptors; in this review, we provide an in-depth characterization of 5-HT2B receptors. Activation of these receptors triggers numerous intracellular signaling cascades that regulate expression of multiple genes. Astroglial 5-HT2B receptors are activated by serotonin-specific reuptake inhibitors, such as major anti-depressant fluoxetine. Expression of astroglial serotonin receptors undergoes remarkable changes in depression disorders, and these changes can be corrected by chronic treatment with anti-depressant drugs.Expert commentary: Depressive behaviors, which occur in rodents following chronic stress or in neurotoxic models of Parkinson disease, are associated with significant changes in the expression of astroglial, but not neuronal 5-HT2B receptors; while therapy with anti-depressants normalizes both receptors expression and depressive behavioral phenotype. In summary, astroglial serotonin receptors are linked to mood disorders and may represent a novel target for cell- and molecule-specific therapies of depression and mood disorders.
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Affiliation(s)
- Liang Peng
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, PR China
| | - Dan Song
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, PR China
| | - Baoman Li
- Laboratory of Metabolic Brain Diseases, Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang, PR China
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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16
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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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17
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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: 876] [Impact Index Per Article: 146.0] [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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18
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Verkhratsky A, Nedergaard M. The homeostatic astroglia emerges from evolutionary specialization of neural cells. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0428. [PMID: 27377722 DOI: 10.1098/rstb.2015.0428] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2016] [Indexed: 12/15/2022] Open
Abstract
Evolution of the nervous system progressed through cellular diversification and specialization of functions. Conceptually, the nervous system is composed from electrically excitable neuronal networks connected with chemical synapses and non-excitable glial cells that provide for homeostasis and defence. Astrocytes are integrated into neural networks through multipartite synapses; astroglial perisynaptic processes closely enwrap synaptic contacts and control homeostasis of the synaptic cleft, supply neurons with glutamate and GABA obligatory precursor glutamine and contribute to synaptic plasticity, learning and memory. In neuropathology, astrocytes may undergo reactive remodelling or degeneration; to a large extent, astroglial reactions define progression of the pathology and neurological outcome.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain University of Nizhny Novgorod, Nizhny, Novgorod 603022, Russia
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
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19
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Abstract
Rapid advances in Ca2+ imaging techniques enable us to simultaneously monitor the activities of hundreds of astrocytes in the intact brain, thus providing a powerful tool for understanding the functions of both host and engrafted astrocytes in sensory processing in vivo. These techniques include both improved Ca2+ indicators and advanced optical recording methods. Astrocytes in multiple cortical and sub-cortical areas are able to respond to the corresponding sensory modalities. These sensory stimuli produce astrocytic Ca2+ responses through different cellular mechanisms. In addition, it has been suggested that astrocytic gene deficiencies in various sensory systems cause impairments in sensory circuits and cognition. Therefore, glial transplantation would be a potentially interesting approach for the cell-based therapy for glia-related disorders. There are multiple cell sources for glial transplantation, including neural stem cells, glial progenitors, and pluripotent stem cells. Both in vitro and in vivo studies have shown that engrafted astrocytes derived from these cell sources are capable of responding to sensory stimulation by elevating the intracellular Ca2+ concentration. These results indicate that engrafted astrocytes not only morphologically but also functionally integrate into the host neural network. Until now, many animal studies have proven that glial transplantation would be a good choice for treating multiple glial disorders. Together, these studies on the sensory responses of host and engrafted astrocytes have provided us a novel perspective in both neuron-glia circuit functions and future treatment strategies for glial disorders.
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Affiliation(s)
- Kuan Zhang
- Brain Research Center and State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China
| | - Xiaowei Chen
- Brain Research Center and State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University, Chongqing, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
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20
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Zorec R, Parpura V, Vardjan N, Verkhratsky A. Astrocytic face of Alzheimer’s disease. Behav Brain Res 2017; 322:250-257. [DOI: 10.1016/j.bbr.2016.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 04/16/2016] [Accepted: 05/08/2016] [Indexed: 10/21/2022]
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21
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Zorec R, Parpura V, Verkhratsky A. Astroglial Vesicular Trafficking in Neurodegenerative Diseases. Neurochem Res 2016; 42:905-917. [DOI: 10.1007/s11064-016-2055-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 12/20/2022]
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22
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Jurič DM, Kržan M, Lipnik-Stangelj M. Histamine and astrocyte function. Pharmacol Res 2016; 111:774-783. [DOI: 10.1016/j.phrs.2016.07.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/11/2016] [Accepted: 07/24/2016] [Indexed: 12/31/2022]
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23
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Vardjan N, Horvat A, Anderson JE, Yu D, Croom D, Zeng X, Lužnik Z, Kreft M, Teng YD, Kirov SA, Zorec R. Adrenergic activation attenuates astrocyte swelling induced by hypotonicity and neurotrauma. Glia 2016; 64:1034-49. [PMID: 27018061 DOI: 10.1002/glia.22981] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 02/18/2016] [Accepted: 02/18/2016] [Indexed: 12/29/2022]
Abstract
Edema in the central nervous system can rapidly result in life-threatening complications. Vasogenic edema is clinically manageable, but there is no established medical treatment for cytotoxic edema, which affects astrocytes and is a primary trigger of acute post-traumatic neuronal death. To test the hypothesis that adrenergic receptor agonists, including the stress stimulus epinephrine protects neural parenchyma from damage, we characterized its effects on hypotonicity-induced cellular edema in cortical astrocytes by in vivo and in vitro imaging. After epinephrine administration, hypotonicity-induced swelling of astrocytes was markedly reduced and cytosolic 3'-5'-cyclic adenosine monophosphate (cAMP) was increased, as shown by a fluorescence resonance energy transfer nanosensor. Although, the kinetics of epinephrine-induced cAMP signaling was slowed in primary cortical astrocytes exposed to hypotonicity, the swelling reduction by epinephrine was associated with an attenuated hypotonicity-induced cytosolic Ca(2+) excitability, which may be the key to prevent astrocyte swelling. Furthermore, in a rat model of spinal cord injury, epinephrine applied locally markedly reduced neural edema around the contusion epicenter. These findings reveal new targets for the treatment of cellular edema in the central nervous system.
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Affiliation(s)
- Nina Vardjan
- Celica, BIOMEDICAL, Tehnološki park 24, Ljubljana, 1000, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, 1000, Slovenia
| | - Anemari Horvat
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, 1000, Slovenia
| | - Jamie E Anderson
- Departments of Neurosurgery and Physical Medicine & Rehabilitation, Harvard Medical School, Boston, Massachusetts
| | - Dou Yu
- Departments of Neurosurgery and Physical Medicine & Rehabilitation, Harvard Medical School, Boston, Massachusetts
| | - Deborah Croom
- Brain and Behaviour Discovery Institute, Medical College of Georgia, Augusta, Georgia.,Department of Neurosurgery, Medical College of Georgia, Augusta, Georgia
| | - Xiang Zeng
- Departments of Neurosurgery and Physical Medicine & Rehabilitation, Harvard Medical School, Boston, Massachusetts
| | - Zala Lužnik
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, 1000, Slovenia
| | - Marko Kreft
- Celica, BIOMEDICAL, Tehnološki park 24, Ljubljana, 1000, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, 1000, Slovenia.,Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana, 1000, Slovenia
| | - Yang D Teng
- Departments of Neurosurgery and Physical Medicine & Rehabilitation, Harvard Medical School, Boston, Massachusetts.,Division of SCI Research, VA Boston Healthcare System, Boston, Massachusetts
| | - Sergei A Kirov
- Brain and Behaviour Discovery Institute, Medical College of Georgia, Augusta, Georgia.,Department of Neurosurgery, Medical College of Georgia, Augusta, Georgia
| | - Robert Zorec
- Celica, BIOMEDICAL, Tehnološki park 24, Ljubljana, 1000, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, Ljubljana, 1000, Slovenia
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24
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Chrobak AA, Soltys Z. Bergmann Glia, Long-Term Depression, and Autism Spectrum Disorder. Mol Neurobiol 2016; 54:1156-1166. [PMID: 26809583 PMCID: PMC5310553 DOI: 10.1007/s12035-016-9719-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/12/2016] [Indexed: 12/22/2022]
Abstract
Bergmann glia (BG), a specific type of radial astrocytes in the cerebellum, play a variety of vital functions in the development of this structure. However, the possible role of BG in the development of abnormalities observed in individuals with autism spectrum disorder (ASD) seems to be underestimated. One of the most consistent findings observed in ASD patients is loss of Purkinje cells (PCs). Such a defect may be caused by dysregulation of glutamate homeostasis, which is maintained mainly by BG. Moreover, these glial cells are involved in long-term depression (LTD), a form of plasticity which can additionally subserve neuroprotective functions. The aim of presented review is to summarize the current knowledge about interactions which occur between PC and BG, with special emphasis on those which are relevant to the survival and proper functioning of cerebellar neurons.
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Affiliation(s)
- Adrian Andrzej Chrobak
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland. .,Faculty of Medicine, Jagiellonian University Medical College, Kopernika St. 21A, Cracow, 31-501, Poland.
| | - Zbigniew Soltys
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Gronostajowa St. 9, Cracow, 30-387, Poland
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25
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Horvat A, Zorec R, Vardjan N. Adrenergic stimulation of single rat astrocytes results in distinct temporal changes in intracellular Ca(2+) and cAMP-dependent PKA responses. Cell Calcium 2016; 59:156-63. [PMID: 26794933 DOI: 10.1016/j.ceca.2016.01.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 01/24/2023]
Abstract
During the arousal and startle response, locus coeruleus neurons, innervating practically all brain regions, release catecholamine noradrenaline, which reaches neural brain cells, including astrocytes. These glial cells respond to noradrenergic stimulation by simultaneous activation of the α- and β-adrenergic receptors (ARs) in the plasma membrane with increasing cytosolic levels of Ca(2+) and cAMP, respectively. AR-activation controls a myriad of processes in astrocytes including glucose metabolism, gliosignal vesicle homeostasis, gene transcription, cell morphology and antigen-presenting functions, all of which have distinct temporal characteristics. It is known from biochemical studies that Ca(2+) and cAMP signals in astrocytes can interact, however it is presently unclear whether the temporal properties of the two second messengers are time associated upon AR-activation. We used confocal microscopy to study AR agonist-induced intracellular changes in Ca(2+) and cAMP in single cultured cortical rat astrocytes by real-time monitoring of the Ca(2+) indicator Fluo4-AM and the fluorescence resonance energy transfer-based nanosensor A-kinase activity reporter 2 (AKAR2), which reports the activity of cAMP via its downstream effector protein kinase A (PKA). The results revealed that the activation of α1-ARs by phenylephrine triggers periodic (phasic) Ca(2+) oscillations within 10s, while the activation of β-ARs by isoprenaline leads to a ∼10-fold slower tonic rise to a plateau in cAMP/PKA activity devoid of oscillations. Thus the concomitant activation of α- and β-ARs triggers the Ca(2+) and cAMP second messenger systems in astrocytes with distinct temporal properties, which appears to be tailored to regulate downstream effectors in different time domains.
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Affiliation(s)
- Anemari Horvat
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia.
| | - Nina Vardjan
- Laboratory of Neuroendocrinology - Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; Celica Biomedical, Tehnološki park 24, 1000 Ljubljana, Slovenia.
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26
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Zorec R, Horvat A, Vardjan N, Verkhratsky A. Memory Formation Shaped by Astroglia. Front Integr Neurosci 2015; 9:56. [PMID: 26635551 PMCID: PMC4648070 DOI: 10.3389/fnint.2015.00056] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Accepted: 10/28/2015] [Indexed: 12/13/2022] Open
Abstract
Astrocytes, the most heterogeneous glial cells in the central nervous system (CNS), execute a multitude of homeostatic functions and contribute to memory formation. Consolidation of synaptic and systemic memory is a prolonged process and hours are required to form long-term memory. In the past, neurons or their parts have been considered to be the exclusive cellular sites of these processes, however, it has now become evident that astrocytes provide an important and essential contribution to memory formation. Astrocytes participate in the morphological remodeling associated with synaptic plasticity, an energy-demanding process that requires mobilization of glycogen, which, in the CNS, is almost exclusively stored in astrocytes. Synaptic remodeling also involves bidirectional astroglial-neuronal communication supported by astroglial receptors and release of gliosignaling molecules. Astroglia exhibit cytoplasmic excitability that engages second messengers, such as Ca2+, for phasic, and cyclic adenosine monophosphate (cAMP), for tonic signal coordination with neuronal processes. The detection of signals by astrocytes and the release of gliosignaling molecules, in particular by vesicle-based mechanisms, occurs with a significant delay after stimulation, orders of magnitude longer than that present in stimulus–secretion coupling in neurons. These particular arrangements position astrocytes as integrators ideally tuned to support time-dependent memory formation.
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Affiliation(s)
- Robert Zorec
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana Ljubljana, Slovenia ; Celica Biomedical Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana Ljubljana, Slovenia ; Celica Biomedical Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Laboratory of Neuroendocrinology and Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana Ljubljana, Slovenia ; Celica Biomedical Ljubljana, Slovenia ; Faculty of Life Sciences, University of Manchester Manchester, UK ; Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science Bilbao, Spain ; Department of Neurosciences, University of the Basque Country Leioa, Spain ; University of Nizhny Novgorod Nizhny Novgorod, Russia
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27
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Norepinephrine-induced calcium signaling in astrocytes in the respiratory network of the ventrolateral medulla. Respir Physiol Neurobiol 2015; 226:18-23. [PMID: 26514085 DOI: 10.1016/j.resp.2015.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 11/22/2022]
Abstract
The neuronal activity in the respiratory network of the ventrolateral medulla strongly depends on a variety of different neuromodulators. Since the respiratory activity generated by neurons in the pre-Bötzinger complex (preBötC) is stabilized by astrocytes, we investigated potential effects of the neuromodulator norepinephrine (NE) on the astrocytic calcium signaling in the ventral respiratory group. In acutely isolated brainstem slices from wild type mice (postnatal day 1-10) we performed calcium imaging experiments using Oregon Green 488 BAPTA-1 AM as a calcium indicator dye. Astrocytes in the preBötC, which were identified by their unique intracellular calcium rise after the reduction of the extracellular K(+) concentration, showed calcium rises in response to norepinephrine. These calcium signals persisted after blockade of neuronal activity by tetrodotoxin (TTX) indicating that they were independent of neuronal activity. Furthermore, application of the endoplasmic reticulum calcium pump blocker cyclopiazonic acid (CPA) diminished norepinephrine-induced calcium signals. This results could be confirmed using transgenic mice with astrocyte specific expression of GCaMP3. Thus, norepinephrine might, apart from acting directly on neurons, influence and modulate respiratory network activity via the modulation of astroglial calcium signaling.
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28
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De Zeeuw CI, Hoogland TM. Reappraisal of Bergmann glial cells as modulators of cerebellar circuit function. Front Cell Neurosci 2015; 9:246. [PMID: 26190972 PMCID: PMC4488625 DOI: 10.3389/fncel.2015.00246] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 06/17/2015] [Indexed: 11/13/2022] Open
Abstract
Just as there is a huge morphological and functional diversity of neuron types specialized for specific aspects of information processing in the brain, astrocytes have equally distinct morphologies and functions that aid optimal functioning of the circuits in which they are embedded. One type of astrocyte, the Bergmann glial cell (BG) of the cerebellum, is a prime example of a highly diversified astrocyte type, the architecture of which is adapted to the cerebellar circuit and facilitates an impressive range of functions that optimize information processing in the adult brain. In this review we expand on the function of the BG in the cerebellum to highlight the importance of astrocytes not only in housekeeping functions, but also in contributing to plasticity and information processing in the cerebellum.
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Affiliation(s)
- Chris I De Zeeuw
- Cerebellar Coordination and Cognition, Netherlands Institute for Neuroscience Amsterdam, Netherlands ; Department of Neuroscience, Erasmus MC Rotterdam, Netherlands
| | - Tycho M Hoogland
- Cerebellar Coordination and Cognition, Netherlands Institute for Neuroscience Amsterdam, Netherlands ; Department of Neuroscience, Erasmus MC Rotterdam, Netherlands
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29
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Verkhratsky A, Parpura V. Physiology of Astroglia: Channels, Receptors, Transporters, Ion Signaling and Gliotransmission. ACTA ACUST UNITED AC 2015. [DOI: 10.4199/c00123ed1v01y201501ngl004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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30
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Li B, Zhu JN, Wang JJ. Histaminergic afferent system in the cerebellum: structure and function. CEREBELLUM & ATAXIAS 2014; 1:5. [PMID: 26331029 PMCID: PMC4549136 DOI: 10.1186/2053-8871-1-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 03/14/2014] [Indexed: 12/16/2022]
Abstract
Histaminergic afferent system of the cerebellum, having been considered as an essential component of the direct hypothalamocerebellar circuits, originates from the tuberomammillary nucleus in the hypothalamus. Unlike the mossy fibers and climbing fibers, the histaminergic afferent fibers, a third type of cerebellar afferents, extend fine varicose fibers throughout the cerebellar cortex and nuclei. Histamine receptors, belonging to the family of G protein-coupled receptors, are widely present in the cerebellum. Through these histamine receptors, histamine directly excites Purkinje cells and granule cells in the cerebellar cortex, as well as the cerebellar nuclear neurons. Therefore, the histaminergic afferents parallelly modulate these dominant components in the cerebellar circuitry and consequently influence the final output of the cerebellum. In this way, the histaminergic afferent system actively participates in the cerebellum-mediated motor balance and coordination and nonsomatic functions. Accordingly, histaminergic reagents may become potential drugs for clinical treatment of cerebellar ataxia and other cerebellar disease. On the other hand, considering the hypothalamus is a high regulatory center for autonomic and visceral activities, the hypothalamocerebellar histaminergic fibers/projections, bridging the nonsomatic center to somatic structure, may play a critical role in the somatic-nonsomatic integration.
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Affiliation(s)
- Bin Li
- Department of Biological Science and Technology and State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093 China
| | - Jing-Ning Zhu
- Department of Biological Science and Technology and State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093 China
| | - Jian-Jun Wang
- Department of Biological Science and Technology and State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093 China
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31
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Verkhratsky A, Burnstock G. Purinergic and glutamatergic receptors on astroglia. ADVANCES IN NEUROBIOLOGY 2014; 11:55-79. [PMID: 25236724 DOI: 10.1007/978-3-319-08894-5_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astroglial cells express many neurotransmitter receptors; the receptors to glutamate and ATP being the most abundant. Here, we provide a concise overview on the expression and main properties of astroglial glutamate receptors (ionotropic receptors represented by AMPA and NMDA subtypes) and metabotropic (mainly mGluR5 and mGluR3 subtypes) and purinoceptors (adenosine receptors of A1, A2A, A2B, and A3 types, ionotropic P2X1/5 and P2X7 subtypes, and metabotropic P2Y purinoceptors). We also discuss the role of these receptors in glial physiology and pathophysiology.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, School of Biological Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester, M13 9PT, UK,
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Hirono M, Nagao S, Obata K. Developmental α2-adrenergic regulation of noradrenergic synaptic facilitation at cerebellar GABAergic synapses. Neuroscience 2014; 256:242-51. [DOI: 10.1016/j.neuroscience.2013.10.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
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Ding F, O'Donnell J, Thrane AS, Zeppenfeld D, Kang H, Xie L, Wang F, Nedergaard M. α1-Adrenergic receptors mediate coordinated Ca2+ signaling of cortical astrocytes in awake, behaving mice. Cell Calcium 2013; 54:387-94. [PMID: 24138901 DOI: 10.1016/j.ceca.2013.09.001] [Citation(s) in RCA: 263] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 09/13/2013] [Accepted: 09/16/2013] [Indexed: 12/31/2022]
Abstract
Astrocyte Ca2+ signals in awake behaving mice are widespread, coordinated and differ fundamentally from the locally restricted Ca2+ transients observed ex vivo and in anesthetized animals. Here we show that the synchronized release of norepinephrine (NE) from locus coeruleus (LC) projections throughout the cerebral cortex mediate long-ranging Ca2+ signals by activation of astrocytic α1-adrenergic receptors. When LC output was triggered by either physiological sensory (whisker) stimulation or an air-puff startle response, astrocytes responded with fast Ca2+ transients that encompassed the entire imaged field (positioned over either frontal or parietal cortex). The application of adrenergic inhibitors, including α1-adrenergic antagonist prazosin, potently suppressed both evoked, as well as the frequently observed spontaneous astroglial Ca2+ signals. The LC-specific neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), which reduced cortical NE content by >90%, prevented nearly all astrocytic Ca2+ signals in awake mice. The observations indicate that in adult, unanesthetized mice, astrocytes do not respond directly to glutamatergic signaling evoked by sensory stimulation. Instead astrocytes appear to be the primary target for NE, with astrocytic Ca2+ signaling being triggered by the α1-adrenergic receptor. In turn, astrocytes may coordinate the broad effects of neuromodulators on neuronal activity.
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Affiliation(s)
- Fengfei Ding
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - John O'Donnell
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - Alexander S Thrane
- Department of Ophthalmology, Haukeland University Hospital, Bergen 5021, Norway
| | - Douglas Zeppenfeld
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - Hongyi Kang
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - Lulu Xie
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - Fushun Wang
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, New York 14642
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Reyes RC, Verkhratsky A, Parpura V. TRPC1-mediated Ca2+ and Na+ signalling in astroglia: differential filtering of extracellular cations. Cell Calcium 2013; 54:120-5. [PMID: 23764169 DOI: 10.1016/j.ceca.2013.05.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Canonical transient receptor potential 1 (TRPC1) plasmalemmal cation channels mediate Ca2+ and Na+ fluxes and control respective cytoplasmic ion signals in rat cortical astrocytes. Mechanical stimulation of astrocytes results in an increase in the levels of cytosolic Ca2+ and Na+ that are in part due to entry of extracellular cations through TRPC1 containing channels. Inhibition of the TRPC1 pore with an antibody against its selective filter reduced cytosolic Ca2+ accumulation caused by mechanical stimulation. In contrast, this immunological treatment increased the cytosolic Na+ peak accumulation induced by mechanical stimulation. We propose that TRPC channels are amenable to changes in selective filtering, as mutations in previous studies and antibody binding in our present study differentially affect the flux of Ca2) and Na+. TRPC1 containing channels might represent focal points for co-ordination of Ca2+ and Na+ signalling in astroglia and this can have consequences on Ca(2+)- and Na(+)-dependent processes such as regulated exocytosis and lactate production, respectively, which in turn can modulate neuronal synaptic transmission.
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Affiliation(s)
- Reno C Reyes
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA
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Verkhratsky A, Parpura V. Store-operated calcium entry in neuroglia. Neurosci Bull 2013; 30:125-33. [PMID: 23677809 DOI: 10.1007/s12264-013-1343-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 02/14/2013] [Indexed: 11/30/2022] Open
Abstract
Neuroglial cells are homeostatic neural cells. Generally, they are electrically non-excitable and their activation is associated with the generation of complex intracellular Ca(2+) signals that define the "Ca(2+) excitability" of glia. In mammalian glial cells the major source of Ca(2+) for this excitability is the lumen of the endoplasmic reticulum (ER), which is ultimately (re)filled from the extracellular space. This occurs via store-operated Ca(2+) entry (SOCE) which is supported by a specific signaling system connecting the ER with plasmalemmal Ca(2+) entry. Here, emptying of the ER Ca(2+) store is necessary and sufficient for the activation of SOCE, and without Ca(2+) influx via SOCE the ER store cannot be refilled. The molecular arrangements underlying SOCE are relatively complex and include plasmalemmal channels, ER Ca(2+) sensors, such as stromal interaction molecule, and possibly ER Ca(2+) pumps (of the SERCA type). There are at least two sets of plasmalemmal channels mediating SOCE, the Ca(2+)-release activated channels, Orai, and transient receptor potential (TRP) channels. The molecular identity of neuroglial SOCE has not been yet identified unequivocally. However, it seems that Orai is predominantly expressed in microglia, whereas astrocytes and oligodendrocytes rely more on TRP channels to produce SOCE. In physiological conditions the SOCE pathway is instrumental for the sustained phase of the Ca(2+) signal observed following stimulation of metabotropic receptors on glial cells.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK,
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Parpura V, Verkhratsky A. The astrocyte excitability brief: From receptors to gliotransmission. Neurochem Int 2012; 61:610-21. [DOI: 10.1016/j.neuint.2011.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 11/14/2011] [Accepted: 12/01/2011] [Indexed: 01/23/2023]
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Tamamushi S, Nakamura T, Inoue T, Ebisui E, Sugiura K, Bannai H, Mikoshiba K. Type 2 inositol 1,4,5-trisphosphate receptor is predominantly involved in agonist-induced Ca2+ signaling in Bergmann glia. Neurosci Res 2012; 74:32-41. [DOI: 10.1016/j.neures.2012.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 06/27/2012] [Indexed: 10/28/2022]
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Verkhratsky A, Rodríguez JJ, Parpura V. Calcium signalling in astroglia. Mol Cell Endocrinol 2012; 353:45-56. [PMID: 21945602 DOI: 10.1016/j.mce.2011.08.039] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/28/2011] [Accepted: 08/31/2011] [Indexed: 12/15/2022]
Abstract
Astroglia possess excitability based on movements of Ca(2+) ions between intracellular compartments and plasmalemmal Ca(2+) fluxes. This "Ca(2+) excitability" is controlled by several families of proteins located in the plasma membrane, within the cytosol and in the intracellular organelles, most notably in the endoplasmic reticulum (ER) and mitochondria. Accumulation of cytosolic Ca(2+) can be caused by the entry of Ca(2+) from the extracellular space through ionotropic receptors and store-operated channels expressed in astrocytes. Plasmalemmal Ca(2+) ATP-ase and sodium-calcium exchanger extrude cytosolic Ca(2+) to the extracellular space; the exchanger can also operate in reverse, depending of the intercellular Na(+) concentration, to deliver Ca(2+) to the cytosol. The ER internal store possesses inositol 1,4,5-trisphosphate receptors which can be activated upon stimulation of astrocytes through a multiple plasma membrane metabotropic G-protein coupled receptors. This leads to release of Ca(2+) from the ER and its elevation in the cytosol, the level of which can be modulated by mitochondria. The mitochondrial uniporter takes up Ca(2+) into the matrix, while free Ca(2+) exits the matrix through the mitochondrial Na(+)/Ca(2+) exchanger as well as via transient openings of the mitochondrial permeability transition pore. One of the prominent consequences of astroglial Ca(2+) excitability is gliotransmission, a release of transmitters from astroglia which can lead to signalling to adjacent neurones.
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Verkhratsky A, Rodríguez JJ, Parpura V. Neurotransmitters and integration in neuronal-astroglial networks. Neurochem Res 2012; 37:2326-38. [PMID: 22476701 DOI: 10.1007/s11064-012-0765-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/18/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
Two major neural cell types, glia, astrocytes in particular, and neurones can release chemical transmitters that act as soluble signalling compounds for intercellular communication. Exocytosis, a process which depends on an increase in cytosolic Ca(2+) levels, represents a common denominator for release of neurotransmitters, stored in secretory vesicles, from these neural cells. While neurones rely predominately on the immediate entry of Ca(2+) from the extracellular space to the cytosol in this process, astrocytes support their cytosolic Ca(2+) increases by appropriating this ion from the intracellular endoplasmic reticulum store and extracellular space. Additionally, astrocytes can release neurotransmitters using a variety of non-vesicular pathways which are mediated by an assortment of plasmalemmal channels and transporters. Once a neuronal and/or astrocytic neurotransmitter is released into the extracellular space, it can activate plasma membrane neurotransmitter receptors on neural cells, causing autocrine and/or paracrine signalling. Moreover, chemical transmission is essential not only for homocellular, but also for heterocellular bi-directional communication in the brain. Further detailed understanding of chemical transmission will aid our comprehension of the brain (dys)function in heath and disease.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK.
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Abstract
Astroglial cells, due to their passive electrical properties, were long considered subservient to neurons and to merely provide the framework and metabolic support of the brain. Although astrocytes do play such structural and housekeeping roles in the brain, these glial cells also contribute to the brain's computational power and behavioural output. These more active functions are endowed by the Ca2+-based excitability displayed by astrocytes. An increase in cytosolic Ca2+ levels in astrocytes can lead to the release of signalling molecules, a process termed gliotransmission, via the process of regulated exocytosis. Dynamic components of astrocytic exocytosis include the vesicular-plasma membrane secretory machinery, as well as the vesicular traffic, which is governed not only by general cytoskeletal elements but also by astrocyte-specific IFs (intermediate filaments). Gliotransmitters released into the ECS (extracellular space) can exert their actions on neighbouring neurons, to modulate synaptic transmission and plasticity, and to affect behaviour by modulating the sleep homoeostat. Besides these novel physiological roles, astrocytic Ca2+ dynamics, Ca2+-dependent gliotransmission and astrocyte–neuron signalling have been also implicated in brain disorders, such as epilepsy. The aim of this review is to highlight the newer findings concerning Ca2+ signalling in astrocytes and exocytotic gliotransmission. For this we report on Ca2+ sources and sinks that are necessary and sufficient for regulating the exocytotic release of gliotransmitters and discuss secretory machinery, secretory vesicles and vesicle mobility regulation. Finally, we consider the exocytotic gliotransmission in the modulation of synaptic transmission and plasticity, as well as the astrocytic contribution to sleep behaviour and epilepsy.
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Parpura V, Heneka MT, Montana V, Oliet SHR, Schousboe A, Haydon PG, Stout RF, Spray DC, Reichenbach A, Pannicke T, Pekny M, Pekna M, Zorec R, Verkhratsky A. Glial cells in (patho)physiology. J Neurochem 2012; 121:4-27. [PMID: 22251135 DOI: 10.1111/j.1471-4159.2012.07664.x] [Citation(s) in RCA: 398] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neuroglial cells define brain homeostasis and mount defense against pathological insults. Astroglia regulate neurogenesis and development of brain circuits. In the adult brain, astrocytes enter into intimate dynamic relationship with neurons, especially at synaptic sites where they functionally form the tripartite synapse. At these sites, astrocytes regulate ion and neurotransmitter homeostasis, metabolically support neurons and monitor synaptic activity; one of the readouts of the latter manifests in astrocytic intracellular Ca(2+) signals. This form of astrocytic excitability can lead to release of chemical transmitters via Ca(2+) -dependent exocytosis. Once in the extracellular space, gliotransmitters can modulate synaptic plasticity and cause changes in behavior. Besides these physiological tasks, astrocytes are fundamental for progression and outcome of neurological diseases. In Alzheimer's disease, for example, astrocytes may contribute to the etiology of this disorder. Highly lethal glial-derived tumors use signaling trickery to coerce normal brain cells to assist tumor invasiveness. This review not only sheds new light on the brain operation in health and disease, but also points to many unknowns.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, Alabama, USA.
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Abstract
The name astroglia unifies many non-excitable neural cells that act as primary homeostatic cells in the nervous system. Neuronal activity triggers multiple homeostatic responses of astroglia that include increase in metabolic activity and synthesis of neuronal preferred energy substrate lactate, clearance of neurotransmitters and buffering of extracellular K(+) ions to name but a few. Many (if not all) of astroglial homeostatic responses are controlled by dynamic changes in the cytoplasmic concentration of two cations, Ca(2+) and Na(+). Intracellular concentration of these ions is tightly controlled by several transporters and can be rapidly affected by the activation of respective fluxes through ionic channels or ion exchangers. Here, we provide a comprehensive review of astroglial Ca(2+) and Na(+) signalling.
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Morales AP, Carvalho ACP, Monteforte PT, Hirata H, Han SW, Hsu YT, Smaili SS. Endoplasmic Reticulum Calcium Release Engages Bax Translocation in Cortical Astrocytes. Neurochem Res 2011; 36:829-38. [DOI: 10.1007/s11064-011-0411-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2011] [Indexed: 11/25/2022]
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Parpura V, Grubišić V, Verkhratsky A. Ca(2+) sources for the exocytotic release of glutamate from astrocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:984-91. [PMID: 21118669 DOI: 10.1016/j.bbamcr.2010.11.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 11/07/2010] [Accepted: 11/10/2010] [Indexed: 01/26/2023]
Abstract
Astrocytes can exocytotically release the gliotransmitter glutamate from vesicular compartments. Increased cytosolic Ca(2+) concentration is necessary and sufficient for this process. The predominant source of Ca(2+) for exocytosis in astrocytes resides within the endoplasmic reticulum (ER). Inositol 1,4,5-trisphosphate and ryanodine receptors of the ER provide a conduit for the release of Ca(2+) to the cytosol. The ER store is (re)filled by the store-specific Ca(2+)-ATPase. Ultimately, the depleted ER is replenished by Ca(2+) which enters from the extracellular space to the cytosol via store-operated Ca(2+) entry; the TRPC1 protein has been implicated in this part of the astrocytic exocytotic process. Voltage-gated Ca(2+) channels and plasma membrane Na(+)/Ca(2+) exchangers are additional means for cytosolic Ca(2+) entry. Cytosolic Ca(2+) levels can be modulated by mitochondria, which can take up cytosolic Ca(2+) via the Ca(2+) uniporter and release Ca(2+) into cytosol via the mitochondrial Na(+)/Ca(2+) exchanger, as well as by the formation of the mitochondrial permeability transition pore. The interplay between various Ca(2+) sources generates cytosolic Ca(2+) dynamics that can drive Ca(2+)-dependent exocytotic release of glutamate from astrocytes. An understanding of this process in vivo will reveal some of the astrocytic functions in health and disease of the brain. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy and Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham 35294-0021, USA.
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Verkhratsky A. Physiology of neuronal–glial networking. Neurochem Int 2010; 57:332-43. [DOI: 10.1016/j.neuint.2010.02.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 01/05/2010] [Accepted: 02/01/2010] [Indexed: 10/19/2022]
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Hertz L, Lovatt D, Goldman SA, Nedergaard M. Adrenoceptors in brain: cellular gene expression and effects on astrocytic metabolism and [Ca(2+)]i. Neurochem Int 2010; 57:411-20. [PMID: 20380860 PMCID: PMC2934885 DOI: 10.1016/j.neuint.2010.03.019] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2009] [Revised: 03/02/2010] [Accepted: 03/31/2010] [Indexed: 11/24/2022]
Abstract
Recent in vivo studies have established astrocytes as a major target for locus coeruleus activation (Bekar et al., 2008), renewing interest in cell culture studies on noradrenergic effects on astrocytes in primary cultures and calling for additional information about the expression of adrenoceptor subtypes on different types of brain cells. In the present communication, mRNA expression of alpha(1)-, alpha(2)- and beta-adrenergic receptors and their subtypes was determined in freshly isolated, cell marker-defined populations of astrocytes, NG2-positive cells, microglia, endothelial cells, and Thy1-positive neurons (mainly glutamatergic projection neurons) in murine cerebral cortex. Immediately after dissection of frontal, parietal and occipital cortex of 10-12-week-old transgenic mice, which combined each cell-type marker with a specific fluorescent signal, the tissue was digested, triturated and centrifuged, yielding a solution of dissociated cells of all types, which were separated by fluorescence-activated cell sorting (FACS). mRNA expression in each cell fraction was determined by microarray analysis. alpha(1A)-Receptors were unequivocally expressed in astrocytes and NG2-positive cells, but absent in other cell types, and alpha(1B)-receptors were not expressed in any cell population. Among alpha(2)-receptors only alpha(2A)-receptors were expressed, unequivocally in astrocytes and NG-positive cells, tentatively in microglia and questionably in Thy1-positive neurons and endothelial cells. beta(1)-Receptors were unequivocally expressed in astrocytes, tentatively in microglia, and questionably in neurons and endothelial cells, whereas beta(2)-adrenergic receptors showed tentative expression in neurons and astrocytes and unequivocal expression in other cell types. This distribution was supported by immunochemical data and its relevance established by previous studies in well-differentiated primary cultures of mouse astrocytes, showing that stimulation of alpha(2)-adrenoceptors increases glycogen formation and oxidative metabolism, the latter by a mechanism depending on intramitochondrial Ca(2+), whereas alpha(1)-adrenoceptor stimulation enhances glutamate uptake, and beta-adrenoceptor activation causes glycogenolysis and increased Na(+), K(+)-ATPase activity. The Ca(2+)- and cAMP-mediated association between energy-consuming and energy-yielding processes is emphasized.
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MESH Headings
- Animals
- Astrocytes/metabolism
- Brain Chemistry/genetics
- Brain Chemistry/physiology
- Calcium Signaling/physiology
- Cell Separation
- Cells, Cultured
- Flow Cytometry
- Gene Expression/physiology
- Glucose/metabolism
- Glycogen/metabolism
- Mice
- Mice, Transgenic/physiology
- Microarray Analysis
- Mitochondria/metabolism
- Oxidation-Reduction
- Pyruvic Acid/metabolism
- RNA/biosynthesis
- RNA/genetics
- Receptors, Adrenergic/biosynthesis
- Receptors, Adrenergic/genetics
- Receptors, Adrenergic, alpha-1/biosynthesis
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-2/biosynthesis
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, beta/biosynthesis
- Receptors, Adrenergic, beta/genetics
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Affiliation(s)
- Leif Hertz
- Department of Clinical Pharmacology, College of Basic Medical Sciences, China Medical University, Shenyang, P. R. China
| | - Ditte Lovatt
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Steven A. Goldman
- Department of Neurology, University of Rochester Medical Center, Rochester, NY 14642
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY 14642
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Verkhratsky A, Olabarria M, Noristani HN, Yeh CY, Rodriguez JJ. Astrocytes in Alzheimer's disease. Neurotherapeutics 2010; 7:399-412. [PMID: 20880504 PMCID: PMC5084302 DOI: 10.1016/j.nurt.2010.05.017] [Citation(s) in RCA: 312] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/25/2010] [Accepted: 05/10/2010] [Indexed: 11/24/2022] Open
Abstract
The circuitry of the human brain is formed by neuronal networks embedded into astroglial syncytia. The astrocytes perform numerous functions, providing for the overall brain homeostasis, assisting in neurogenesis, determining the micro-architecture of the grey matter, and defending the brain through evolutionary conserved astrogliosis programs. Astroglial cells are engaged in neurological diseases by determining the progression and outcome of neuropathological process. Astrocytes are specifically involved in various neurodegenerative diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and various forms of dementia. Recent evidence suggest that early stages of neurodegenerative processes are associated with atrophy of astroglia, which causes disruptions in synaptic connectivity, disbalance in neurotransmitter homeostasis, and neuronal death through increased excitotoxicity. At the later stages, astrocytes become activated and contribute to the neuroinflammatory component of neurodegeneration.
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Affiliation(s)
- Alexei Verkhratsky
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
- grid.11480.3c0000000121671098Ikerbasque, Basque Foundation for Science, Department of Neuroscience, The University of the Basque Country UPV/EHU, Technological Park, Bldg. 205, Floor-1, Laida Bidea, 48170 Zamudio, Vizcaya Spain
| | - Markel Olabarria
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Harun N. Noristani
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Chia-Yu Yeh
- grid.5379.80000000121662407Faculty of Life Sciences, The University of Manchester, M13 9PT Manchester, UK
| | - Jose Julio Rodriguez
- grid.418095.10000000110153316Institute of Experimental Medicine, ASCR, 142 20 Prague, Czech Republic
- grid.424810.b0000000404672314Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
- grid.11480.3c0000000121671098Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain
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Ionotropic receptors in neuronal-astroglial signalling: what is the role of "excitable" molecules in non-excitable cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:992-1002. [PMID: 20869992 DOI: 10.1016/j.bbamcr.2010.09.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 09/13/2010] [Accepted: 09/16/2010] [Indexed: 01/02/2023]
Abstract
Astroglial cells were long considered to serve merely as the structural and metabolic supporting cast and scenery against which the shining neurones perform their illustrious duties. Relatively recent evidence, however, indicates that astrocytes are intimately involved in many of the brain's functions. Astrocytes possess a diverse assortment of ionotropic transmitter receptors, which enable these glial cells to respond to many of the same signals that act on neurones. Ionotropic receptors mediate neurone-driven signals to astroglial cells in various brain areas including neocortex, hippocampus and cerebellum. Activation of ionotropic receptors trigger rapid signalling events in astroglia; these events, represented by local Ca(2+) or Na(+) signals provide the mechanism for fast neuronal-glial signalling at the synaptic level. Since astrocytes can detect chemical transmitters that are released from neurones and can release their own extracellular signals, gliotransmitters, they are intricately involved in homocellular and heterocellular signalling mechanisms in the nervous system. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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Verkhratsky A, Parpura V. Recent advances in (patho)physiology of astroglia. Acta Pharmacol Sin 2010; 31:1044-54. [PMID: 20694024 DOI: 10.1038/aps.2010.108] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Our view of astrocytes in the operation of the brain is changing dramatically over the last 3 decades. Astroglial calcium excitability controls the release of gliotransmitters, which can occur at the tripartite synapse. Astrocytes not only modulate synaptic transmission by releasing and taking up transmitters, but also receiving neuronal signals that act upon astrocytic plasma membrane receptors. This process represents the bidirectional neurone-glia communication. Additionally, astrocytes play role in the regulation of blood flow as well as ion and water homeostasis. Many of the brain dysfunctions are primary astropathies, including hepatic encephalopathy and Alexander disease, while other brain malfunctions, such as epilepsy and Alzheimer disease, may have substantial astrocytic contribution. Thus, these star-shaped cells by their roles in (patho)physiology of the brain seem to live up to the expectation one can have from their given name - astrocyte.
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Kuhn SA, Mueller U, Hanisch UK, Regenbrecht CRA, Schoenwald I, Brodhun M, Kosmehl H, Ewald C, Kalff R, Reichart R. Glioblastoma cells express functional cell membrane receptors activated by daily used medical drugs. J Cancer Res Clin Oncol 2009; 135:1729-45. [PMID: 19543745 PMCID: PMC2847174 DOI: 10.1007/s00432-009-0620-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Accepted: 06/02/2009] [Indexed: 12/11/2022]
Abstract
PURPOSE Calcium ions are highly versatile spacial and temporal intracellular signals of non-excitable cells and have an important impact on nearly every aspect of cellular life controlling cell growth, metabolism, fluid secretion, information processing, transcription, apoptosis, and motility. Neurons and glia respond to stimuli, including neurotransmitters, neuromodulators, and hormones, which increase the intracellular calcium concentration. The function of intracellular calcium in gliomas is unknown. Lots of daily used drugs may act via receptors that can be linked to the intracellular calcium system and therefore could influence glioma biology. METHODS Glioma cells were loaded with the calcium ion sensitive dye Fura 2-AM. Subsequently, cells were stimulated with 25 different medical drugs for 30 s. The increase of free intracellular calcium ions was measured and calculated by a microscope-camera-computer-unit. RESULTS Except for the buffer solution HEPES that served as negative control and for the cortisol derivative dexamethasone, all other 24 tested drugs induced a rise of intracellular calcium ions. The cellular calcium responses were classified into seven functional groups. The tested substances activated several types of calcium channels and receptors. CONCLUSIONS Our study impressively demonstrates that medical drugs are potent inducers of intracellular calcium signals. Totally unexpected, the results show a high amount of functional cellular receptors and channels on glioma cells, which could be responsible for certain biological effects like migration and cell growth. This calcium imaging study proves the usability of the calcium imaging as a screening system for functional receptors on human glioma cells.
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Affiliation(s)
- Susanne A Kuhn
- Department of Neurosurgery, Medical Center, Friedrich-Schiller-University, Erlanger Allee 101, 07747 Jena, Germany.
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