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Riveros ME, Leibold NK, Retamal MA, Ezquer F. Role of histaminergic regulation of astrocytes in alcohol use disorder. Prog Neuropsychopharmacol Biol Psychiatry 2024; 133:111009. [PMID: 38653364 DOI: 10.1016/j.pnpbp.2024.111009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/26/2024] [Accepted: 04/14/2024] [Indexed: 04/25/2024]
Abstract
Alcohol use disorder (AUD) is a severe, yet not fully understood, mental health problem. It is associated with liver, pancreatic, and gastrointestinal diseases, thereby highly increasing the morbidity and mortality of these individuals. Currently, there is no effective and safe pharmacological therapy for AUD. Therefore, there is an urgent need to increase our knowledge about its neurophysiological etiology to develop new treatments specifically targeted at this health condition. Recent findings have shown an upregulation in the histaminergic system both in alcohol dependent individuals and in animals with high alcohol preference. The use of H3 histaminergic receptor antagonists has given promising therapeutic results in animal models of AUD. Interestingly, astrocytes, which are ubiquitously present in the brain, express the three main histamine receptors (H1, H2 and H3), and in the last few years, several studies have shown that astrocytes could play an important role in the development and maintenance of AUD. Accordingly, alterations in the density of astrocytes in brain areas such as the prefrontal cortex, ventral striatum, and hippocampus that are critical for AUD-related characteristics have been observed. These characteristics include addiction, impulsivity, motor function, and aggression. In this work, we review the current state of knowledge on the relationship between the histaminergic system and astrocytes in AUD and propose that histamine could increase alcohol tolerance by protecting astrocytes from ethanol-induced oxidative stress. This increased tolerance could lead to high levels of alcohol intake and therefore could be a key factor in the development of alcohol dependence.
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Affiliation(s)
- María Eugenia Riveros
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.
| | - Nicole K Leibold
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health and Life Sciences (FHML), Maastricht University, Maastricht, the Netherlands
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile; Programa de Comunicación Celular en Cáncer, Instituto de Ciencia e Innovación en Medicina, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Fernando Ezquer
- Centro de Medicina Regenerativa, Instituto de Ciencia e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago. Chile; Research Center for the Development of Novel Therapeutic Alternatives for Alcohol Use Disorders, Santiago, Chile
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2
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Ye Q, Li J, Ren WJ, Zhang Y, Wang T, Rubini P, Yin HY, Illes P, Tang Y. Astrocyte activation in hindlimb somatosensory cortex contributes to electroacupuncture analgesia in acid-induced pain. Front Neurol 2024; 15:1348038. [PMID: 38633538 PMCID: PMC11021577 DOI: 10.3389/fneur.2024.1348038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 03/11/2024] [Indexed: 04/19/2024] Open
Abstract
Background Several studies have confirmed the direct relationship between extracellular acidification and the occurrence of pain. As an effective pain management approach, the mechanism of electroacupuncture (EA) treatment of acidification-induced pain is not fully understood. The purpose of this study was to assess the analgesic effect of EA in this type of pain and to explore the underlying mechanism(s). Methods We used plantar injection of the acidified phosphate-buffered saline (PBS; pH 6.0) to trigger thermal hyperalgesia in male Sprague-Dawley (SD) rats aged 6-8 weeks. The value of thermal withdrawal latency (TWL) was quantified after applying EA stimulation to the ST36 acupoint and/or chemogenetic control of astrocytes in the hindlimb somatosensory cortex. Results Both EA and chemogenetic astrocyte activation suppressed the acid-induced thermal hyperalgesia in the rat paw, whereas inhibition of astrocyte activation did not influence the hyperalgesia. At the same time, EA-induced analgesia was blocked by chemogenetic inhibition of astrocytes. Conclusion The present results suggest that EA-activated astrocytes in the hindlimb somatosensory cortex exert an analgesic effect on acid-induced pain, although these astrocytes might only moderately regulate acid-induced pain in the absence of EA. Our results imply a novel mode of action of astrocytes involved in EA analgesia.
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Affiliation(s)
- Qing Ye
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jie Li
- Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Wen-Jing Ren
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Ying Zhang
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Tao Wang
- Chongqing Traditional Chinese Medicine Hospital, Chongqing, China
| | - Patrizia Rubini
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Hai-Yan Yin
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Peter Illes
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Rudolf Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany
| | - Yong Tang
- International Joint Research Centre on Purinergic Signalling, School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Acupuncture and Chronobiology Key Laboratory of Sichuan Province, School of Health and Rehabilitation, Chengdu University of Traditional Chinese Medicine, Chengdu, China
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Gao Z, Wu L, Zhao X, Wei Z, Lu L, Yi M. Random fluctuations and synaptic plasticity enhance working memory activities in the neuron-astrocyte network. Cogn Neurodyn 2024; 18:503-518. [PMID: 38699624 PMCID: PMC11061073 DOI: 10.1007/s11571-023-10002-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/30/2023] [Accepted: 08/13/2023] [Indexed: 05/05/2024] Open
Abstract
Random fluctuations are inescapable feature in biological systems, but appropriate intensity of randomness can effectively facilitate information transfer and memory encoding within the nervous system. In the study, a modified spiking neuron-astrocyte network model with excitatory-inhibitory balance and synaptic plasticity is established. This model considers external input noise, and allows investigating the effects of intrinsic random fluctuations on working memory tasks. It is found that the astrocyte network, acting as a low-pass filter, reduces the noise component of the total input currents and improves the recovered images. The memory performance is enhanced by selecting appropriate intensity of random fluctuations, while excessive intensity can inhibit signal transmission of network. As the intensity of random fluctuations gradually increases, there exists a maximum value of the working memory performance. The cued recall of the network markedly decreases excessive input noise relative to test images. Meanwhile, a greater contrast effect is observed as the external input noise increases. In addition, synaptic plasticity reduces the firing rates and firing peaks of neurons, thus stabilizing the working memory activity during the test. The outcomes of this study may provide some inspirations for comprehending the role of random fluctuations in working memory mechanisms and neural information processing within the cerebral cortex.
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Affiliation(s)
- Zhuoheng Gao
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
| | - Liqing Wu
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
| | - Xin Zhao
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
| | - Zhuochao Wei
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
| | - Lulu Lu
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
| | - Ming Yi
- School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074 China
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4
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Rose CR, Verkhratsky A. Sodium homeostasis and signalling: The core and the hub of astrocyte function. Cell Calcium 2024; 117:102817. [PMID: 37979342 DOI: 10.1016/j.ceca.2023.102817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/20/2023] [Indexed: 11/20/2023]
Abstract
Neuronal activity and neurochemical stimulation trigger spatio-temporal changes in the cytoplasmic concentration of Na+ ions in astrocytes. These changes constitute the substrate for Na+ signalling and are fundamental for astrocytic excitability. Astrocytic Na+ signals are generated by Na+ influx through neurotransmitter transporters, with primary contribution of glutamate transporters, and through cationic channels; whereas recovery from Na+ transients is mediated mainly by the plasmalemmal Na+/K+ ATPase. Astrocytic Na+ signals regulate the activity of plasmalemmal transporters critical for homeostatic function of astrocytes, thus providing real-time coordination between neuronal activity and astrocytic support.
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Affiliation(s)
- Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
| | - Alexej Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, United Kingdom; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China; International Collaborative Center on Big Science Plan for Purinergic Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, China; Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, LT-01102, Vilnius, Lithuania.
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5
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Bhatt M, Di Iacovo A, Romanazzi T, Roseti C, Bossi E. Betaine-The dark knight of the brain. Basic Clin Pharmacol Toxicol 2023; 133:485-495. [PMID: 36735640 DOI: 10.1111/bcpt.13839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/20/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023]
Abstract
The role of betaine in the liver and kidney has been well documented, even from the cellular and molecular point of view. Despite literature reporting positive effects of betaine supplementation in Alzheimer's, Parkinson's and schizophrenia, the role and function of betaine in the brain are little studied and reviewed. Beneficial effects of betaine in neurodegeneration, excitatory and inhibitory imbalance and against oxidative stress in the central nervous system (CNS) have been collected and analysed to understand the main role of betaine in the brain. There are many 'dark' aspects needed to complete the picture. The understanding of how this osmolyte is transported across neuron and glial cells is also controversial, as the expression levels and functioning of the known protein capable to transport betaine expressed in the brain, betaine-GABA transporter 1 (BGT-1), is itself not well clarified. The reported actions of betaine beyond BGT-1 related to neuronal degeneration and memory impairment are the focus of this work. With this review, we underline the scarcity of detailed molecular and cellular information about betaine action. Consequently, the requirement of detailed focus on and study of the interaction of this molecule with CNS components to sustain the therapeutic use of betaine.
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Affiliation(s)
- Manan Bhatt
- Department of Biotechnology and Life Sciences, Laboratory of Cellular and Molecular Physiology, University of Insubria, Varese, Italy
- School of Experimental and Translational Medicine, University of Insubria, Varese, Italy
| | - Angela Di Iacovo
- Department of Biotechnology and Life Sciences, Laboratory of Cellular and Molecular Physiology, University of Insubria, Varese, Italy
- School of Experimental and Translational Medicine, University of Insubria, Varese, Italy
| | - Tiziana Romanazzi
- Department of Biotechnology and Life Sciences, Laboratory of Cellular and Molecular Physiology, University of Insubria, Varese, Italy
- School of Experimental and Translational Medicine, University of Insubria, Varese, Italy
| | - Cristina Roseti
- Department of Biotechnology and Life Sciences, Laboratory of Cellular and Molecular Physiology, University of Insubria, Varese, Italy
- Centre for Neuroscience, University of Insubria, Varese, Italy
| | - Elena Bossi
- Department of Biotechnology and Life Sciences, Laboratory of Cellular and Molecular Physiology, University of Insubria, Varese, Italy
- Centre for Neuroscience, University of Insubria, Varese, Italy
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Purushotham SS, Buskila Y. Astrocytic modulation of neuronal signalling. FRONTIERS IN NETWORK PHYSIOLOGY 2023; 3:1205544. [PMID: 37332623 PMCID: PMC10269688 DOI: 10.3389/fnetp.2023.1205544] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 05/18/2023] [Indexed: 06/20/2023]
Abstract
Neuronal signalling is a key element in neuronal communication and is essential for the proper functioning of the CNS. Astrocytes, the most prominent glia in the brain play a key role in modulating neuronal signalling at the molecular, synaptic, cellular, and network levels. Over the past few decades, our knowledge about astrocytes and their functioning has evolved from considering them as merely a brain glue that provides structural support to neurons, to key communication elements. Astrocytes can regulate the activity of neurons by controlling the concentrations of ions and neurotransmitters in the extracellular milieu, as well as releasing chemicals and gliotransmitters that modulate neuronal activity. The aim of this review is to summarise the main processes through which astrocytes are modulating brain function. We will systematically distinguish between direct and indirect pathways in which astrocytes affect neuronal signalling at all levels. Lastly, we will summarize pathological conditions that arise once these signalling pathways are impaired focusing on neurodegeneration.
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Affiliation(s)
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- The MARCS Institute, Western Sydney University, Campbelltown, NSW, Australia
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Costa RT, Santos MB, Alberto-Silva C, Carrettiero DC, Ribeiro CAJ. Methylmalonic Acid Impairs Cell Respiration and Glutamate Uptake in C6 Rat Glioma Cells: Implications for Methylmalonic Acidemia. Cell Mol Neurobiol 2023; 43:1163-1180. [PMID: 35674974 DOI: 10.1007/s10571-022-01236-1] [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: 01/07/2022] [Accepted: 05/20/2022] [Indexed: 11/28/2022]
Abstract
Methylmalonic acidemia is an organic acidemia caused by deficient activity of L-methylmalonyl-CoA mutase or its cofactor cyanocobalamin and it is biochemically characterized by an accumulation of methylmalonic acid (MMA) in tissue and body fluids of patients. The main clinical manifestations of this disease are neurological and observable symptoms during metabolic decompensation are encephalopathy, cerebral atrophy, coma, and seizures, which commonly appear in newborns. This study aimed to investigate the toxic effects of MMA in a glial cell line presenting astrocytic features. Astroglial C6 cells were exposed to MMA (0.1-10 mM) for 24 or 48 h and cell metabolic viability, glucose consumption, and oxygen consumption rate, as well as glutamate uptake and ATP content were analyzed. The possible preventive effects of bezafibrate were also evaluated. MMA significantly reduced cell metabolic viability after 48-h period and increased glucose consumption during the same period of incubation. Regarding the energy homeostasis, MMA significantly reduced respiratory parameters of cells after 48-h exposure, indicating that cell metabolism is compromised at resting and reserve capacity state, which might influence the cell capacity to meet energetic demands. Glutamate uptake and ATP content were also compromised after exposure to MMA, which can be influenced energy metabolism impairment, affecting the functionality of the astroglial cells. Our findings suggest that these effects could be involved in the pathophysiology of neurological dysfunction of this disease. Methylmalonic acid compromises mitochondrial functioning leading to reduced ATP production and reduces glutamate uptake by C6 astroglial cells.
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Affiliation(s)
- Renata T Costa
- Centro de Ciências Naturais E Humanas (CCNH), UFABC - Universidade Federal do ABC, Alameda da Universidade, s/n, São Bernardo do Campo, SP, CEP 09606-045, Brazil
| | - Marcella B Santos
- Centro de Ciências Naturais E Humanas (CCNH), UFABC - Universidade Federal do ABC, Alameda da Universidade, s/n, São Bernardo do Campo, SP, CEP 09606-045, Brazil
| | - Carlos Alberto-Silva
- Centro de Ciências Naturais E Humanas (CCNH), UFABC - Universidade Federal do ABC, Alameda da Universidade, s/n, São Bernardo do Campo, SP, CEP 09606-045, Brazil
| | - Daniel C Carrettiero
- Centro de Ciências Naturais E Humanas (CCNH), UFABC - Universidade Federal do ABC, Alameda da Universidade, s/n, São Bernardo do Campo, SP, CEP 09606-045, Brazil
| | - César A J Ribeiro
- Centro de Ciências Naturais E Humanas (CCNH), UFABC - Universidade Federal do ABC, Alameda da Universidade, s/n, São Bernardo do Campo, SP, CEP 09606-045, Brazil.
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8
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Cruz-Mendoza F, Luquin S, García-Estrada J, Fernández-Quezada D, Jauregui-Huerta F. Acoustic Stress Induces Opposite Proliferative/Transformative Effects in Hippocampal Glia. Int J Mol Sci 2023; 24:ijms24065520. [PMID: 36982594 PMCID: PMC10058072 DOI: 10.3390/ijms24065520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/09/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023] Open
Abstract
The hippocampus is a brain region crucially involved in regulating stress responses and highly sensitive to environmental changes, with elevated proliferative and adaptive activity of neurons and glial cells. Despite the prevalence of environmental noise as a stressor, its effects on hippocampal cytoarchitecture remain largely unknown. In this study, we aimed to investigate the impact of acoustic stress on hippocampal proliferation and glial cytoarchitecture in adult male rats, using environmental noise as a stress model. After 21 days of noise exposure, our results showed abnormal cellular proliferation in the hippocampus, with an inverse effect on the proliferation ratios of astrocytes and microglia. Both cell lineages also displayed atrophic morphologies with fewer processes and lower densities in the noise-stressed animals. Our findings suggest that, stress not only affects neurogenesis and neuronal death in the hippocampus, but also the proliferation ratio, cell density, and morphology of glial cells, potentially triggering an inflammatory-like response that compromises their homeostatic and repair functions.
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Lohr C. Role of P2Y receptors in astrocyte physiology and pathophysiology. Neuropharmacology 2023; 223:109311. [PMID: 36328064 DOI: 10.1016/j.neuropharm.2022.109311] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022]
Abstract
Astrocytes are active constituents of the brain that manage ion homeostasis and metabolic support of neurons and directly tune synaptic transmission and plasticity. Astrocytes express all known P2Y receptors. These regulate a multitude of physiological functions such as cell proliferation, Ca2+ signalling, gliotransmitter release and neurovascular coupling. In addition, P2Y receptors are fundamental in the transition of astrocytes into reactive astrocytes, as occurring in many brain disorders such as neurodegenerative diseases, neuroinflammation and epilepsy. This review summarizes the current literature addressing the function of P2Y receptors in astrocytes in the healthy brain as well as in brain diseases.
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Affiliation(s)
- Christian Lohr
- Institute of Cell and Systems Biology of Animals, University of Hamburg, Germany.
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10
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Thapaliya P, Pape N, Rose CR, Ullah G. Modeling the heterogeneity of sodium and calcium homeostasis between cortical and hippocampal astrocytes and its impact on bioenergetics. Front Cell Neurosci 2023; 17:1035553. [PMID: 36794264 PMCID: PMC9922870 DOI: 10.3389/fncel.2023.1035553] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 01/13/2023] [Indexed: 01/31/2023] Open
Abstract
Emerging evidence indicates that neuronal activity-evoked changes in sodium concentration in astrocytes Na a represent a special form of excitability, which is tightly linked to all other major ions in the astrocyte and extracellular space, as well as to bioenergetics, neurotransmitter uptake, and neurovascular coupling. Recently, one of us reported that Na a transients in the neocortex have a significantly higher amplitude than those in the hippocampus. Based on the extensive data from that study, here we develop a detailed biophysical model to further understand the origin of this heterogeneity and how it affects bioenergetics in the astrocytes. In addition to closely fitting the observed experimental Na a changes under different conditions, our model shows that the heterogeneity in Na a signaling leads to substantial differences in the dynamics of astrocytic Ca2+ signals in the two brain regions, and leaves cortical astrocytes more susceptible to Na+ and Ca2+ overload under metabolic stress. The model also predicts that activity-evoked Na a transients result in significantly larger ATP consumption in cortical astrocytes than in the hippocampus. The difference in ATP consumption is mainly due to the different expression levels of NMDA receptors in the two regions. We confirm predictions from our model experimentally by fluorescence-based measurement of glutamate-induced changes in ATP levels in neocortical and hippocampal astrocytes in the absence and presence of the NMDA receptor's antagonist (2R)-amino-5-phosphonovaleric acid.
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Affiliation(s)
- Pawan Thapaliya
- Department of Physics, University of South Florida, Tampa, FL, United States
| | - Nils Pape
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Christine R. Rose
- Faculty of Mathematics and Natural Sciences, Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL, United States,*Correspondence: Ghanim Ullah ✉
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11
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The complex role of inflammation and gliotransmitters in Parkinson's disease. Neurobiol Dis 2023; 176:105940. [PMID: 36470499 PMCID: PMC10372760 DOI: 10.1016/j.nbd.2022.105940] [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: 06/06/2022] [Revised: 11/28/2022] [Accepted: 12/01/2022] [Indexed: 12/09/2022] Open
Abstract
Our understanding of the role of innate and adaptive immune cell function in brain health and how it goes awry during aging and neurodegenerative diseases is still in its infancy. Inflammation and immunological dysfunction are common components of Parkinson's disease (PD), both in terms of motor and non-motor components of PD. In recent decades, the antiquated notion that the central nervous system (CNS) in disease states is an immune-privileged organ, has been debunked. The immune landscape in the CNS influences peripheral systems, and peripheral immunological changes can alter the CNS in health and disease. Identifying immune and inflammatory pathways that compromise neuronal health and survival is critical in designing innovative and effective strategies to limit their untoward effects on neuronal health.
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12
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Barber CN, Goldschmidt HL, Lilley B, Bygrave AM, Johnson RC, Huganir RL, Zack DJ, Raben DM. Differential expression patterns of phospholipase D isoforms 1 and 2 in the mammalian brain and retina. J Lipid Res 2022; 63:100247. [PMID: 35764123 PMCID: PMC9305353 DOI: 10.1016/j.jlr.2022.100247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/10/2022] [Accepted: 06/20/2022] [Indexed: 01/16/2023] Open
Abstract
Phosphatidic acid is a key signaling molecule heavily implicated in exocytosis due to its protein-binding partners and propensity to induce negative membrane curvature. One phosphatidic acid-producing enzyme, phospholipase D (PLD), has also been implicated in neurotransmission. Unfortunately, due to the unreliability of reagents, there has been confusion in the literature regarding the expression of PLD isoforms in the mammalian brain which has hampered our understanding of their functional roles in neurons. To address this, we generated epitope-tagged PLD1 and PLD2 knockin mice using CRISPR/Cas9. Using these mice, we show that PLD1 and PLD2 are both localized at synapses by adulthood, with PLD2 expression being considerably higher in glial cells and PLD1 expression predominating in neurons. Interestingly, we observed that only PLD1 is expressed in the mouse retina, where it is found in the synaptic plexiform layers. These data provide critical information regarding the localization and potential role of PLDs in the central nervous system.
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Affiliation(s)
- Casey N Barber
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hana L Goldschmidt
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Brendan Lilley
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alexei M Bygrave
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Richard C Johnson
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Richard L Huganir
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Donald J Zack
- Department of Ophthalmology, Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel M Raben
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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13
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Li K, Ly K, Mehta S, Braithwaite A. Importance of crosstalk between the microbiota and the neuroimmune system for tissue homeostasis. Clin Transl Immunology 2022; 11:e1394. [PMID: 35620584 PMCID: PMC9125509 DOI: 10.1002/cti2.1394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/30/2022] [Accepted: 05/01/2022] [Indexed: 11/23/2022] Open
Abstract
The principal function of inflammation is cellular defence against ‘danger signals’ such as tissue injury and pathogen infection to maintain the homeostasis of the organism. The initiation and progression of inflammation are not autonomous as there is substantial evidence that inflammation is known to be strongly influenced by ‘neuroimmune crosstalk’, involving the production and expression of soluble signalling molecules that interact with cell surface receptors. In addition, microbiota have been found to be involved in the development and function of the nervous and immune systems and play an important role in health and disease. Herein, we provide an outline of the mechanisms of neuroimmune communication in the regulation of inflammation and immune response and then provide evidence for the involvement of microbiota in the development and functions of the host nervous and immune systems. It appears that the nervous and immune systems in multicellular organisms have co‐evolved with the microbiota, such that all components are in communication to maximise the ability of the organism to adapt to a wide range of environmental stresses to maintain or restore tissue homeostasis.
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Affiliation(s)
- Kunyu Li
- Department of Pathology Dunedin School of Medicine University of Otago Dunedin New Zealand
| | - Kevin Ly
- Department of Pathology Dunedin School of Medicine University of Otago Dunedin New Zealand
| | - Sunali Mehta
- Department of Pathology Dunedin School of Medicine University of Otago Dunedin New Zealand
| | - Antony Braithwaite
- Department of Pathology Dunedin School of Medicine University of Otago Dunedin New Zealand
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Puma DDL, Ripoli C, Puliatti G, Pastore F, Lazzarino G, Tavazzi B, Arancio O, Piacentini R, Grassi C. Extracellular tau oligomers affect extracellular glutamate handling by astrocytes through downregulation of GLT-1 expression and impairment of NKA1A2 function. Neuropathol Appl Neurobiol 2022; 48:e12811. [PMID: 35274343 PMCID: PMC9262805 DOI: 10.1111/nan.12811] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 02/14/2022] [Accepted: 02/26/2022] [Indexed: 11/29/2022]
Abstract
AIMS Several studies reported that astrocytes support neuronal communication by the release of gliotransmitters, including ATP and glutamate. Astrocytes also play a fundamental role in buffering extracellular glutamate in the synaptic cleft, thus limiting the risk of excitotoxicity in neurons. We previously demonstrated that extracellular tau oligomers (ex-oTau), by specifically targeting astrocytes, affect glutamate-dependent synaptic transmission via a reduction in gliotransmitter release. The aim of this work was to determine if ex-oTau also impair the ability of astrocytes to uptake extracellular glutamate, thus further contributing to ex-oTau-dependent neuronal dysfunction. METHODS Primary cultures of astrocytes and organotypic brain slices were exposed to ex-oTau (200 nM) for 1 hour. Extracellular glutamate buffering by astrocytes was studied by: Na+ imaging; electrophysiological recordings; high-performance liquid chromatography; Western blot and immunofluorescence. Experimental paradigms avoiding ex-oTau internalization (i.e., heparin pre-treatment and amyloid precursor protein knockout astrocytes) were used to dissect intracellular vs. extracellular effects of oTau. RESULTS Ex-oTau uploading in astrocytes significantly affected glutamate-transporter-1 expression and function, thus impinging on glutamate buffering activity. Ex-oTau also reduced Na-K-ATPase activity because of pump mislocalization on the plasma membrane, with no significant changes in expression. This effect was independent of oTau internalization and it caused Na+ overload and membrane depolarization in ex-oTau-targeted astrocytes. CONCLUSIONS Ex-oTau exerted a complex action on astrocytes, at both intracellular and extracellular levels. The net effect was dysregulated glutamate signalling in terms of both release and uptake that relied on reduced expression of glutamate-transporter-1, altered function and localization of NKA1A1, and NKA1A2. Consequently, Na+ gradients and all Na+ -dependent transports were affected.
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Affiliation(s)
- Domenica Donatella Li Puma
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Cristian Ripoli
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Giulia Puliatti
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Francesco Pastore
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Giacomo Lazzarino
- UniCamillus Saint Camillus International University of Health Sciences, Rome, Italy
| | - Barbara Tavazzi
- UniCamillus Saint Camillus International University of Health Sciences, Rome, Italy
| | - Ottavio Arancio
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, and Department of Medicine, Columbia University, New York, NY, United States
| | - Roberto Piacentini
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Claudio Grassi
- Department of Neuroscience, Università Cattolica del Sacro Cuore, Rome, Italy.,Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
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15
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Kovács Z, Skatchkov SN, Veh RW, Szabó Z, Németh K, Szabó PT, Kardos J, Héja L. Critical Role of Astrocytic Polyamine and GABA Metabolism in Epileptogenesis. Front Cell Neurosci 2022; 15:787319. [PMID: 35069115 PMCID: PMC8770812 DOI: 10.3389/fncel.2021.787319] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/09/2021] [Indexed: 12/22/2022] Open
Abstract
Accumulating evidence indicate that astrocytes are essential players of the excitatory and inhibitory signaling during normal and epileptiform activity via uptake and release of gliotransmitters, ions, and other substances. Polyamines can be regarded as gliotransmitters since they are almost exclusively stored in astrocytes and can be released by various mechanisms. The polyamine putrescine (PUT) is utilized to synthesize GABA, which can also be released from astrocytes and provide tonic inhibition on neurons. The polyamine spermine (SPM), synthesized form PUT through spermidine (SPD), is known to unblock astrocytic Cx43 gap junction channels and therefore facilitate astrocytic synchronization. In addition, SPM released from astrocytes may also modulate neuronal NMDA, AMPA, and kainate receptors. As a consequence, astrocytic polyamines possess the capability to significantly modulate epileptiform activity. In this study, we investigated different steps in polyamine metabolism and coupled GABA release to assess their potential to control seizure generation and maintenance in two different epilepsy models: the low-[Mg2+] model of temporal lobe epilepsy in vitro and in the WAG/Rij rat model of absence epilepsy in vivo. We show that SPM is a gliotransmitter that is released from astrocytes and significantly contributes to network excitation. Importantly, we found that inhibition of SPD synthesis completely prevented seizure generation in WAG/Rij rats. We hypothesize that this antiepileptic effect is attributed to the subsequent enhancement of PUT to GABA conversion in astrocytes, leading to GABA release through GAT-2/3 transporters. This interpretation is supported by the observation that antiepileptic potential of the Food and Drug Administration (FDA)-approved drug levetiracetam can be diminished by specifically blocking astrocytic GAT-2/3 with SNAP-5114, suggesting that levetiracetam exerts its effect by increasing surface expression of GAT-2/3. Our findings conclusively suggest that the major pathway through which astrocytic polyamines contribute to epileptiform activity is the production of GABA. Modulation of astrocytic polyamine levels, therefore, may serve for a more effective antiepileptic drug development in the future.
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Affiliation(s)
- Zsolt Kovács
- Department of Biology, ELTE Eötvös Loránd University, Savaria University Centre, Szombathely, Hungary
| | - Serguei N. Skatchkov
- Department of Physiology, Universidad Central Del Caribe, Bayamon, PR, United States
- Department of Biochemistry, Universidad Central Del Caribe, Bayamon, PR, United States
| | - Rüdiger W. Veh
- Institut für Zell- und Neurobiologie, Centrum 2, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Krisztina Németh
- MS Metabolomics Research Group, Centre for Structural Study, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Pál T. Szabó
- MS Metabolomics Research Group, Centre for Structural Study, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Eötvös Loránd Research Network, Budapest, Hungary
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16
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Verisokin AY, Verveyko DV, Postnov DE, Brazhe AR. Modeling of Astrocyte Networks: Toward Realistic Topology and Dynamics. Front Cell Neurosci 2021; 15:645068. [PMID: 33746715 PMCID: PMC7973220 DOI: 10.3389/fncel.2021.645068] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/09/2021] [Indexed: 12/14/2022] Open
Abstract
Neuronal firing and neuron-to-neuron synaptic wiring are currently widely described as orchestrated by astrocytes—elaborately ramified glial cells tiling the cortical and hippocampal space into non-overlapping domains, each covering hundreds of individual dendrites and hundreds thousands synapses. A key component to astrocytic signaling is the dynamics of cytosolic Ca2+ which displays multiscale spatiotemporal patterns from short confined elemental Ca2+ events (puffs) to Ca2+ waves expanding through many cells. Here, we synthesize the current understanding of astrocyte morphology, coupling local synaptic activity to astrocytic Ca2+ in perisynaptic astrocytic processes and morphology-defined mechanisms of Ca2+ regulation in a distributed model. To this end, we build simplified realistic data-driven spatial network templates and compile model equations as defined by local cell morphology. The input to the model is spatially uncorrelated stochastic synaptic activity. The proposed modeling approach is validated by statistics of simulated Ca2+ transients at a single cell level. In multicellular templates we observe regular sequences of cell entrainment in Ca2+ waves, as a result of interplay between stochastic input and morphology variability between individual astrocytes. Our approach adds spatial dimension to the existing astrocyte models by employment of realistic morphology while retaining enough flexibility and scalability to be embedded in multiscale heterocellular models of neural tissue. We conclude that the proposed approach provides a useful description of neuron-driven Ca2+-activity in the astrocyte syncytium.
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Affiliation(s)
| | - Darya V Verveyko
- Department of Theoretical Physics, Kursk State University, Kursk, Russia
| | - Dmitry E Postnov
- Department of Optics and Biophotonics, Saratov State University, Saratov, Russia
| | - Alexey R Brazhe
- Department of Biophysics, Biological Faculty, Lomonosov Moscow State University, Moscow, Russia.,Department of Molecular Neurobiology, Institute of Bioorganic Chemistry RAS, Russian Federation, Moscow, Russia
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17
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Popov A, Brazhe A, Denisov P, Sutyagina O, Li L, Lazareva N, Verkhratsky A, Semyanov A. Astrocyte dystrophy in ageing brain parallels impaired synaptic plasticity. Aging Cell 2021; 20:e13334. [PMID: 33675569 PMCID: PMC7963330 DOI: 10.1111/acel.13334] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 12/30/2020] [Accepted: 02/08/2021] [Indexed: 01/02/2023] Open
Abstract
Little is known about age-dependent changes in structure and function of astrocytes and of the impact of these on the cognitive decline in the senescent brain. The prevalent view on the age-dependent increase in reactive astrogliosis and astrocytic hypertrophy requires scrutiny and detailed analysis. Using two-photon microscopy in conjunction with 3D reconstruction, Sholl and volume fraction analysis, we demonstrate a significant reduction in the number and the length of astrocytic processes, in astrocytic territorial domains and in astrocyte-to-astrocyte coupling in the aged brain. Probing physiology of astrocytes with patch clamp, and Ca2+ imaging revealed deficits in K+ and glutamate clearance and spatiotemporal reorganisation of Ca2+ events in old astrocytes. These changes paralleled impaired synaptic long-term potentiation (LTP) in hippocampal CA1 in old mice. Our findings may explain the astroglial mechanisms of age-dependent decline in learning and memory.
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Affiliation(s)
- Alexander Popov
- Shemyakin‐Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
- Institute of NeuroscienceNizhny Novgorod UniversityNizhny NovgorodRussia
| | - Alexey Brazhe
- Shemyakin‐Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
- Faculty of BiologyMoscow State UniversityMoscowRussia
| | - Pavel Denisov
- Shemyakin‐Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
- Institute of NeuroscienceNizhny Novgorod UniversityNizhny NovgorodRussia
| | - Oksana Sutyagina
- Shemyakin‐Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
- Institute of NeuroscienceNizhny Novgorod UniversityNizhny NovgorodRussia
| | - Li Li
- Department of PhysiologyJiaxing University College of MedicineZhejiang ProChina
| | | | - Alexei Verkhratsky
- Sechenov First Moscow State Medical UniversityMoscowRussia
- Faculty of Biology, Medicine and HealthThe University of ManchesterManchesterUK
- Achucarro Center for NeuroscienceIKERBASQUEBasque Foundation for ScienceBilbaoSpain
- Department of NeurosciencesUniversity of the Basque Country UPV/EHU and CIBERNEDLeioaSpain
| | - Alexey Semyanov
- Shemyakin‐Ovchinnikov Institute of Bioorganic ChemistryRussian Academy of SciencesMoscowRussia
- Faculty of BiologyMoscow State UniversityMoscowRussia
- Sechenov First Moscow State Medical UniversityMoscowRussia
- Department of PhysiologyJiaxing University College of MedicineZhejiang ProChina
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18
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Héja L, Szabó Z, Péter M, Kardos J. Spontaneous Ca 2+ Fluctuations Arise in Thin Astrocytic Processes With Real 3D Geometry. Front Cell Neurosci 2021; 15:617989. [PMID: 33732110 PMCID: PMC7957061 DOI: 10.3389/fncel.2021.617989] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/18/2021] [Indexed: 12/16/2022] Open
Abstract
Fluctuations of cytosolic Ca2+ concentration in astrocytes are regarded as a critical non-neuronal signal to regulate neuronal functions. Although such fluctuations can be evoked by neuronal activity, rhythmic astrocytic Ca2+ oscillations may also spontaneously arise. Experimental studies hint that these spontaneous astrocytic Ca2+ oscillations may lie behind different kinds of emerging neuronal synchronized activities, like epileptogenic bursts or slow-wave rhythms. Despite the potential importance of spontaneous Ca2+ oscillations in astrocytes, the mechanism by which they develop is poorly understood. Using simple 3D synapse models and kinetic data of astrocytic Glu transporters (EAATs) and the Na+/Ca2+ exchanger (NCX), we have previously shown that NCX activity alone can generate markedly stable, spontaneous Ca2+ oscillation in the astrocytic leaflet microdomain. Here, we extend that model by incorporating experimentally determined real 3D geometries of 208 excitatory synapses reconstructed from publicly available ultra-resolution electron microscopy datasets. Our simulations predict that the surface/volume ratio (SVR) of peri-synaptic astrocytic processes prominently dictates whether NCX-mediated spontaneous Ca2+ oscillations emerge. We also show that increased levels of intracellular astrocytic Na+ concentration facilitate the appearance of Ca2+ fluctuations. These results further support the principal role of the dynamical reshaping of astrocyte processes in the generation of intrinsic Ca2+ oscillations and their spreading over larger astrocytic compartments.
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Affiliation(s)
- László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences (MTA), Budapest, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences (MTA), Budapest, Hungary
| | - Márton Péter
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences (MTA), Budapest, Hungary.,Hevesy György PhD School of Chemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences (MTA), Budapest, Hungary
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19
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Rurak GM, Woodside B, Aguilar-Valles A, Salmaso N. Astroglial cells as neuroendocrine targets in forebrain development: Implications for sex differences in psychiatric disease. Front Neuroendocrinol 2021; 60:100897. [PMID: 33359797 DOI: 10.1016/j.yfrne.2020.100897] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/05/2020] [Accepted: 12/15/2020] [Indexed: 12/23/2022]
Abstract
Astroglial cells are the most abundant cell type in the mammalian brain. They are implicated in almost every aspect of brain physiology, including maintaining homeostasis, building and maintaining the blood brain barrier, and the development and maturation of neuronal networks. Critically, astroglia also express receptors for gonadal sex hormones, respond rapidly to gonadal hormones, and are able to synthesize hormones. Thus, they are positioned to guide and mediate sexual differentiation of the brain, particularly neuronal networks in typical and pathological conditions. In this review, we describe astroglial involvement in the organization and development of the brain, and consider known sex differences in astroglial responses to understand how astroglial cell-mediated organization may play a role in forebrain sexual dimorphisms in human populations. Finally, we consider how sexually dimorphic astroglial responses and functions in development may lead to sex differences in vulnerability for neuropsychiatric disorders.
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Affiliation(s)
- Gareth M Rurak
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Barbara Woodside
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada; Concordia University, Montreal, Quebec, Canada
| | | | - Natalina Salmaso
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada.
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20
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Felix L, Delekate A, Petzold GC, Rose CR. Sodium Fluctuations in Astroglia and Their Potential Impact on Astrocyte Function. Front Physiol 2020; 11:871. [PMID: 32903427 PMCID: PMC7435049 DOI: 10.3389/fphys.2020.00871] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/29/2020] [Indexed: 12/12/2022] Open
Abstract
Astrocytes are the main cell type responsible for the regulation of brain homeostasis, including the maintenance of ion gradients and neurotransmitter clearance. These processes are tightly coupled to changes in the intracellular sodium (Na+) concentration. While activation of the sodium-potassium-ATPase (NKA) in response to an elevation of extracellular K+ may decrease intracellular Na+, the cotransport of transmitters, such as glutamate, together with Na+ results in an increase in astrocytic Na+. This increase in intracellular Na+ can modulate, for instance, metabolic downstream pathways. Thereby, astrocytes are capable to react on a fast time scale to surrounding neuronal activity via intracellular Na+ fluctuations and adjust energy production to the demand of their environment. Beside the well-documented conventional roles of Na+ signaling mainly mediated through changes in its electrochemical gradient, several recent studies have identified more atypical roles for Na+, including protein interactions leading to changes in their biochemical activity or Na+-dependent regulation of gene expression. In this review, we will address both the conventional as well as the atypical functions of astrocytic Na+ signaling, presenting the role of transporters and channels involved and their implications for physiological processes in the central nervous system (CNS). We will also discuss how these important functions are affected under pathological conditions, including stroke and migraine. We postulate that Na+ is an essential player not only in the maintenance of homeostatic processes but also as a messenger for the fast communication between neurons and astrocytes, adjusting the functional properties of various cellular interaction partners to the needs of the surrounding network.
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Affiliation(s)
- Lisa Felix
- Institute of Neurobiology, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Andrea Delekate
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Division of Vascular Neurology, Department of Neurology, University Hospital Bonn, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
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21
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Tonic GABA A Conductance Favors Spike-Timing-Dependent over Theta-Burst-Induced Long-Term Potentiation in the Hippocampus. J Neurosci 2020; 40:4266-4276. [PMID: 32327534 DOI: 10.1523/jneurosci.2118-19.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 03/21/2020] [Accepted: 04/15/2020] [Indexed: 11/21/2022] Open
Abstract
Synaptic plasticity is triggered by different patterns of network activity. Here, we investigated how LTP in CA3-CA1 synapses induced by different stimulation patterns is affected by tonic GABAA conductances in rat hippocampal slices. Spike-timing-dependent LTP was induced by pairing Schaffer collateral stimulation with antidromic stimulation of CA1 pyramidal neurons. Theta-burst-induced LTP was induced by theta-burst stimulation of Schaffer collaterals. We mimicked increased tonic GABAA conductance by bath application of 30 μm GABA. Surprisingly, tonic GABAA conductance selectively suppressed theta-burst-induced LTP but not spike-timing-dependent LTP. We combined whole-cell patch-clamp electrophysiology, two-photon Ca2+ imaging, glutamate uncaging, and mathematical modeling to dissect the mechanisms underlying these differential effects of tonic GABAA conductance. We found that Ca2+ transients during pairing of an action potential with an EPSP were less sensitive to tonic GABAA conductance-induced shunting inhibition than Ca2+ transients induced by EPSP burst. Our results may explain how different forms of memory are affected by increasing tonic GABAA conductances under physiological or pathologic conditions, as well as under the influence of substances that target extrasynaptic GABAA receptors (e.g., neurosteroids, sedatives, antiepileptic drugs, and alcohol).SIGNIFICANCE STATEMENT Brain activity is associated with neuronal firing and synaptic signaling among neurons. Synaptic plasticity represents a mechanism for learning and memory. However, some neurotransmitters that escape the synaptic cleft or are released by astrocytes can target extrasynaptic receptors. Extrasynaptic GABAA receptors mediate tonic conductances that reduce the excitability of neurons by shunting. This results in the decreased ability for neurons to fire action potentials, but when action potentials are successfully triggered, tonic conductances are unable to reduce them significantly. As such, tonic GABAA conductances have minimal effects on spike-timing-dependent synaptic plasticity while strongly attenuating the plasticity evoked by EPSP bursts. Our findings shed light on how changes in tonic conductances can selectively affect different forms of learning and memory.
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22
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Popov A, Denisov P, Bychkov M, Brazhe A, Lyukmanova E, Shenkarev Z, Lazareva N, Verkhratsky A, Semyanov A. Caloric restriction triggers morphofunctional remodeling of astrocytes and enhances synaptic plasticity in the mouse hippocampus. Cell Death Dis 2020; 11:208. [PMID: 32231202 PMCID: PMC7105492 DOI: 10.1038/s41419-020-2406-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/15/2020] [Accepted: 02/18/2020] [Indexed: 11/22/2022]
Abstract
Calorie-restricted (CR) diet has multiple beneficial effects on brain function. Here we report morphological and functional changes in hippocampal astrocytes in 3-months-old mice subjected to 1 month of the diet. Whole-cell patch-clamp recordings were performed in the CA1 stratum (str.) radiatum astrocytes of hippocampal slices. The cells were also loaded with fluorescent dye through the patch pipette. CR did not affect the number of astrocytic branches but increased the volume fraction (VF) of distal perisynaptic astrocytic leaflets. The astrocyte growth did not lead to a decrease in the cell input resistance, which may be attributed to a decrease in astrocyte coupling through the gap junctions. Western blotting revealed a decrease in the expression of Cx43 but not Cx30. Immunocytochemical analysis demonstrated a decrease in the density and size of Cx43 clusters. Cx30 cluster density did not change, while their size increased in the vicinity of astrocytic soma. CR shortened K+ and glutamate transporter currents in astrocytes in response to 5 × 50 Hz Schaffer collateral stimulation. However, no change in the expression of astrocytic glutamate transporter 1 (GLT-1) was observed, while the level of glutamine synthetase (GS) decreased. These findings suggest that enhanced enwrapping of synapses by the astrocytic leaflets reduces glutamate and K+ spillover. Reduced spillover led to a decreased contribution of extrasynaptic N2B containing N-methyl-D-aspartate receptors (NMDARs) to the tail of burst-induced EPSCs. The magnitude of long-term potentiation (LTP) in the glutamatergic CA3–CA1 synapses was significantly enhanced after CR. This enhancement was abolished by N2B-NMDARs antagonist. Our findings suggest that astrocytic morphofunctional remodeling is responsible for enhanced synaptic plasticity, which provides a basis for improved learning and memory reported after CR.
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Affiliation(s)
- Alexander Popov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia
| | - Pavel Denisov
- University of Nizhny Novgorod, Gagarin Ave. 23, Nizhny Novgorod, 603950, Russia
| | - Maxim Bychkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia
| | - Alexey Brazhe
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia.,Faculty of Biology, Moscow State University, Leninskie Gory 1/12, Moscow, 119234, Russia
| | - Ekaterina Lyukmanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia
| | - Zakhar Shenkarev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia
| | - Natalia Lazareva
- Sechenov First Moscow State Medical University, Bolshaya Pirogovskaya, 19с1, Moscow, 119146, Russia
| | - Alexei Verkhratsky
- 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.
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya street 16/10, Moscow, 117997, Russia. .,Faculty of Biology, Moscow State University, Leninskie Gory 1/12, Moscow, 119234, Russia. .,Sechenov First Moscow State Medical University, Bolshaya Pirogovskaya, 19с1, Moscow, 119146, Russia.
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23
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NCX activity generates spontaneous Ca 2+ oscillations in the astrocytic leaflet microdomain. Cell Calcium 2019; 86:102137. [PMID: 31838438 DOI: 10.1016/j.ceca.2019.102137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/01/2019] [Accepted: 12/01/2019] [Indexed: 12/13/2022]
Abstract
The synergy between synaptic Glu release and astrocytic Glu-Na+ symport is essential to the signalling function of the tripartite synapse. Here we used kinetic data of astrocytic Glu transporters (EAAT) and the Na+/Ca2+ exchanger (NCX) to simulate Glu release, Glu uptake and subsequent Na+ and Ca2+ dynamics in the astrocytic leaflet microdomain following single release event. Model simulations show that Glu-Na+ symport differently affect intracellular [Na+] in synapses with different extent of astrocytic coverage. Surprisingly, NCX activity alone has been shown to generate markedly stable, spontaneous Ca2+ oscillation in the astrocytic leaflet. These on-going oscillations appear when NCX operates either in the forward or reverse direction. We conjecture that intrinsic NCX activity may play a prominent role in the generation of astrocytic Ca2+ oscillations.
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24
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Kardos J, Dobolyi Á, Szabó Z, Simon Á, Lourmet G, Palkovits M, Héja L. Molecular Plasticity of the Nucleus Accumbens Revisited-Astrocytic Waves Shall Rise. Mol Neurobiol 2019; 56:7950-7965. [PMID: 31134458 PMCID: PMC6834761 DOI: 10.1007/s12035-019-1641-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/06/2019] [Indexed: 12/11/2022]
Abstract
Part of the ventral striatal division, the nucleus accumbens (NAc) drives the circuit activity of an entire macrosystem about reward like a "flagship," signaling and leading diverse conducts. Accordingly, NAc neurons feature complex inhibitory phenotypes that assemble to process circuit inputs and generate outputs by exploiting specific arrays of opposite and/or parallel neurotransmitters, neuromodulatory peptides. The resulting complex combinations enable versatile yet specific forms of accumbal circuit plasticity, including maladaptive behaviors. Although reward signaling and behavior are elaborately linked to neuronal circuit activities, it is plausible to propose whether these neuronal ensembles and synaptic islands can be directly controlled by astrocytes, a powerful modulator of neuronal activity. Pioneering studies showed that astrocytes in the NAc sense citrate cycle metabolites and/or ATP and may induce recurrent activation. We argue that the astrocytic calcium, GABA, and Glu signaling and altered sodium and chloride dynamics fundamentally shape metaplasticity by providing active regulatory roles in the synapse- and network-level flexibility of the NAc.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary.
| | - Árpád Dobolyi
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Pázmány Péter sétány 1C, Budapest, 1117, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Guillaume Lourmet
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
| | - Miklós Palkovits
- Human Brain Tissue Bank, Semmelweis University, Tűzoltó utca 58, Budapest, H-1094, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
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25
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Gerkau NJ, Rakers C, Durry S, Petzold GC, Rose CR. Reverse NCX Attenuates Cellular Sodium Loading in Metabolically Compromised Cortex. Cereb Cortex 2019; 28:4264-4280. [PMID: 29136153 DOI: 10.1093/cercor/bhx280] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/04/2017] [Indexed: 01/05/2023] Open
Abstract
In core regions of ischemic stroke, disruption of blood flow causes breakdown of ionic gradients and, ultimately, calcium overload and cell death. In the surrounding penumbra, cells may recover upon reperfusion, but recovery is hampered by additional metabolic demands imposed by peri-infarct depolarizations (PIDs). There is evidence that sodium influx drives PIDs, but no data exist on PID-related sodium accumulations in vivo. Here, we found that PIDs in mouse neocortex are associated with propagating sodium elevations in neurons and astrocytes. Similar transient sodium elevations were induced in acute tissue slices by brief chemical ischemia. Blocking NMDA-receptors dampened sodium and accompanying calcium loads of neurons in tissue slices, while inhibiting glutamate transport diminished sodium influx into astrocytes, but amplified neuronal sodium loads. In both cell types, inhibition of sodium/calcium exchange (NCX) increased sodium transients. Blocking NCX also significantly reduced calcium transients, a result confirmed in vivo. Our study provides the first quantitative data on sodium elevations in peri-infarct regions in vivo. They suggest that sodium influx drives reversal of NCX, triggering a massive secondary calcium elevation while promoting export of sodium. Reported neuroprotective effects of NCX activity in stroke models might thus be related to its dampening of ischemia-induced sodium loading.
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Affiliation(s)
- Niklas J Gerkau
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, Bonn, Germany
| | - Simone Durry
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, Bonn, Germany.,Department of Neurology, University Hospital Bonn, Sigmund-Freud-Str. 25, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
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26
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Calcium(II) oscillations to glucose: An astrocyte relation. Biophys Chem 2019; 252:106195. [PMID: 31195340 DOI: 10.1016/j.bpc.2019.106195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 11/22/2022]
Abstract
Astrocytes, the most common type of glial cell, are critical to the health of the central nervous system. Evidence implies that changes in the astrocyte's cytosolic calcium concentration is part of a central mechanism by which information is passed and processed in the cell, and it is linked to both external stimuli impacting the cell as well as downstream events such as metabolism and neurotransmitter release. This work proposes a novel chemical model to further the understanding of how extracellular signals could affect intracellular calcium dynamics and metabolic processes within the cell.
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27
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Héja L, Simon Á, Szabó Z, Kardos J. Feedback adaptation of synaptic excitability via Glu:Na + symport driven astrocytic GABA and Gln release. Neuropharmacology 2019; 161:107629. [PMID: 31103619 DOI: 10.1016/j.neuropharm.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/30/2019] [Accepted: 05/07/2019] [Indexed: 02/08/2023]
Abstract
Glutamatergic transmission composed of the arriving of action potential at the axon terminal, fast vesicular Glu release, postsynaptic Glu receptor activation, astrocytic Glu clearance and Glu→Gln shuttle is an abundantly investigated phenomenon. Despite its essential role, however, much less is known about the consequences of the mechanistic connotations of Glu:Na+ symport. Due to the coupled Na+ transport, Glu uptake results in significantly elevated intracellular astrocytic [Na+] that markedly alters the driving force of other Na+-coupled astrocytic transporters. The resulting GABA and Gln release by reverse transport through the respective GAT-3 and SNAT3 transporters help to re-establish the physiological Na+ homeostasis without ATP dissipation and consequently leads to enhanced tonic inhibition and replenishment of axonal glutamate pool. Here, we place this emerging astrocytic adjustment of synaptic excitability into the centre of future perspectives. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary.
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28
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Nicaise C, Marneffe C, Bouchat J, Gilloteaux J. Osmotic Demyelination: From an Oligodendrocyte to an Astrocyte Perspective. Int J Mol Sci 2019; 20:E1124. [PMID: 30841618 PMCID: PMC6429405 DOI: 10.3390/ijms20051124] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 12/15/2022] Open
Abstract
Osmotic demyelination syndrome (ODS) is a disorder of the central myelin that is often associated with a precipitous rise of serum sodium. Remarkably, while the myelin and oligodendrocytes of specific brain areas degenerate during the disease, neighboring neurons and axons appear unspoiled, and neuroinflammation appears only once demyelination is well established. In addition to blood‒brain barrier breakdown and microglia activation, astrocyte death is among one of the earliest events during ODS pathology. This review will focus on various aspects of biochemical, molecular and cellular aspects of oligodendrocyte and astrocyte changes in ODS-susceptible brain regions, with an emphasis on the crosstalk between those two glial cells. Emerging evidence pointing to the initiating role of astrocytes in region-specific degeneration are discussed.
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Affiliation(s)
| | - Catherine Marneffe
- Laboratory of Glia Biology (VIB-KU Leuven Center for Brain & Disease Research), Department of Neuroscience, KU Leuven, 3000 Leuven, Belgium.
| | - Joanna Bouchat
- URPhyM-NARILIS, Université de Namur, 5000 Namur, Belgium.
| | - Jacques Gilloteaux
- URPhyM-NARILIS, Université de Namur, 5000 Namur, Belgium.
- Department of Anatomical Sciences, St George's University School of Medicine, Newcastle upon Tyne NE1 8ST, UK.
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29
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Semyanov A. Spatiotemporal pattern of calcium activity in astrocytic network. Cell Calcium 2019; 78:15-25. [DOI: 10.1016/j.ceca.2018.12.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/16/2018] [Accepted: 12/16/2018] [Indexed: 12/22/2022]
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30
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Heterogeneity of Activity-Induced Sodium Transients between Astrocytes of the Mouse Hippocampus and Neocortex: Mechanisms and Consequences. J Neurosci 2019; 39:2620-2634. [PMID: 30737311 DOI: 10.1523/jneurosci.2029-18.2019] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 01/07/2019] [Accepted: 01/23/2019] [Indexed: 01/09/2023] Open
Abstract
Activity-related sodium transients induced by glutamate uptake represent a special form of astrocyte excitability. Astrocytes of the neocortex, as opposed to the hippocampus proper, also express ionotropic glutamate receptors, which might provide additional sodium influx. We compared glutamate-related sodium transients in astrocytes and neurons in slices of the neocortex and hippocampus of juvenile mice of both sexes, using widefield and multiphoton imaging. Stimulation of glutamatergic afferents or glutamate application induced sodium transients that were twice as large in neocortical as in hippocampal astrocytes, despite similar neuronal responses. Astrocyte sodium transients were reduced by ∼50% upon blocking NMDA receptors in the neocortex, but not hippocampus. Neocortical, but not hippocampal, astrocytes exhibited marked sodium increases in response to NMDA. These key differences in sodium signaling were also observed in neonates and in adults. NMDA application evoked local calcium transients in processes of neocortical astrocytes, which were dampened upon blocking sodium/calcium exchange (NCX) with KB-R7943 or SEA0400. Mathematical computation based on our data predict that NMDA-induced sodium increases drive the NCX into reverse mode, resulting in calcium influx. Together, our study reveals a considerable regional heterogeneity in astrocyte sodium transients, which persists throughout postnatal development. Neocortical astrocytes respond with much larger sodium elevations to glutamatergic activity than hippocampal astrocytes. Moreover, neocortical astrocytes experience NMDA-receptor-mediated sodium influx, which hippocampal astrocytes lack, and which drives calcium import through reverse NCX. This pathway thereby links sodium to calcium signaling and represents a new mechanism for the generation of local calcium influx in neocortical astrocytes.SIGNIFICANCE STATEMENT Astrocyte calcium signals play a central role in neuron-glia interaction. Moreover, activity-related sodium transients may represent a new form of astrocyte excitability. Here we show that activation of NMDA receptors results in prominent sodium transients in neocortical, but not hippocampal, astrocytes in the mouse brain. NMDA receptor activation is accompanied by local calcium signaling in processes of neocortical astrocytes, which is augmented by sodium-driven reversal of the sodium/calcium exchanger. Our data demonstrate a significant regional heterogeneity in the magnitude and mechanisms of astrocyte sodium transients. They also suggest a close interrelation between NMDA-receptor-mediated sodium influx and calcium signaling through the reversal of sodium/calcium exchanger, thereby establishing a new pathway for the generation of local calcium signaling in astrocyte processes.
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31
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Riddell N, Faou P, Crewther SG. Short term optical defocus perturbs normal developmental shifts in retina/RPE protein abundance. BMC DEVELOPMENTAL BIOLOGY 2018; 18:18. [PMID: 30157773 PMCID: PMC6116556 DOI: 10.1186/s12861-018-0177-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 08/16/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND Myopia (short-sightedness) affects approximately 1.4 billion people worldwide, and prevalence is increasing. Animal models induced by defocusing lenses show striking similarity with human myopia in terms of morphology and the implicated genetic pathways. Less is known about proteome changes in animals. Thus, the present study aimed to improve understanding of protein pathway responses to lens defocus, with an emphasis on relating expression changes to no lens control development and identifying bidirectional and/or distinct pathways across myopia and hyperopia (long-sightedness) models. RESULTS Quantitative label-free proteomics and gene set enrichment analysis (GSEA) were used to examine protein pathway expression in the retina/RPE of chicks following 6 h and 48 h of myopia induction with - 10 dioptre (D) lenses, hyperopia induction with +10D lenses, or normal no lens rearing. Seventy-one pathways linked to cell development and neuronal maturation were differentially enriched between 6 and 48 h in no lens chicks. The majority of these normal developmental changes were disrupted by lens-wear (47 of 71 pathways), however, only 11 pathways displayed distinct expression profiles across the lens conditions. Most notably, negative lens-wear induced up-regulation of proteins involved in ATP-driven ion transport, calcium homeostasis, and GABA signalling between 6 and 48 h, while the same proteins were down-regulated over time in normally developing chicks. Glutamate and bicarbonate/chloride transporters were also down-regulated over time in normally developing chicks, and positive lens-wear inhibited this down-regulation. CONCLUSIONS The chick retina/RPE proteome undergoes extensive pathway expression shifts during normal development. Most of these pathways are further disrupted by lens-wear. The identified expression patterns suggest close interactions between neurotransmission (as exemplified by increased GABA receptor and synaptic protein expression), cellular ion homeostasis, and associated energy resources during myopia induction. We have also provided novel evidence for changes to SLC-mediated transmembrane transport during hyperopia induction, with potential implications for signalling at the photoreceptor-bipolar synapse. These findings reflect a key role for perturbed neurotransmission and ionic homeostasis in optically-induced refractive errors, and are predicted by our Retinal Ion Driven Efflux (RIDE) model.
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Affiliation(s)
- Nina Riddell
- Department of Psychology and Counselling, School of Psychology and Public Health, La Trobe University, Plenty Rd., Bundoora, Melbourne, VIC, 3083, Australia.
| | - Pierre Faou
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Sciences, La Trobe University, Melbourne, VIC, Australia
| | - Sheila G Crewther
- Department of Psychology and Counselling, School of Psychology and Public Health, La Trobe University, Plenty Rd., Bundoora, Melbourne, VIC, 3083, Australia
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32
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Vodovozov W, Schneider J, Elzoheiry S, Hollnagel JO, Lewen A, Kann O. Metabolic modulation of neuronal gamma-band oscillations. Pflugers Arch 2018; 470:1377-1389. [DOI: 10.1007/s00424-018-2156-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/06/2018] [Accepted: 05/17/2018] [Indexed: 01/08/2023]
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33
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Dong W, Todd AC, Bröer A, Hulme SR, Bröer S, Billups B. PKC-Mediated Modulation of Astrocyte SNAT3 Glutamine Transporter Function at Synapses in Situ. Int J Mol Sci 2018; 19:ijms19040924. [PMID: 29561757 PMCID: PMC5979592 DOI: 10.3390/ijms19040924] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/07/2018] [Accepted: 03/15/2018] [Indexed: 01/13/2023] Open
Abstract
Astrocytes are glial cells that have an intimate physical and functional association with synapses in the brain. One of their main roles is to recycle the neurotransmitters glutamate and gamma-aminobutyric acid (GABA), as a component of the glutamate/GABA-glutamine cycle. They perform this function by sequestering neurotransmitters and releasing glutamine via the neutral amino acid transporter SNAT3. In this way, astrocytes regulate the availability of neurotransmitters and subsequently influence synaptic function. Since many plasma membrane transporters are regulated by protein kinase C (PKC), the aim of this study was to understand how PKC influences SNAT3 glutamine transport in astrocytes located immediately adjacent to synapses. We studied SNAT3 transport by whole-cell patch-clamping and fluorescence pH imaging of single astrocytes in acutely isolated brainstem slices, adjacent to the calyx of the Held synapse. Activation of SNAT3-mediated glutamine transport in these astrocytes was reduced to 77 ± 6% when PKC was activated with phorbol 12-myristate 13-acetate (PMA). This effect was very rapid (within ~20 min) and eliminated by application of bisindolylmaleimide I (Bis I) or 7-hydroxystaurosporine (UCN-01), suggesting that activation of conventional isoforms of PKC reduces SNAT3 function. In addition, cell surface biotinylation experiments in these brain slices show that the amount of SNAT3 in the plasma membrane is reduced by a comparable amount (to 68 ± 5%) upon activation of PKC. This indicates a role for PKC in dynamically controlling the trafficking of SNAT3 transporters in astrocytes in situ. These data demonstrate that PKC rapidly regulates the astrocytic glutamine release mechanism, which would influence the glutamine availability for adjacent synapses and control levels of neurotransmission.
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Affiliation(s)
- Wuxing Dong
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
| | - Alison C Todd
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
- Centre for Discovery Brain Sciences, School of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK.
| | - Angelika Bröer
- Research School of Biology, The Australian National University, Linnaeus Way 134, Canberra ACT 2601, Australia.
| | - Sarah R Hulme
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
| | - Stefan Bröer
- Research School of Biology, The Australian National University, Linnaeus Way 134, Canberra ACT 2601, Australia.
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Canberra ACT 2601, Australia.
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34
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Mo JL, Liu Q, Kou ZW, Wu KW, Yang P, Chen XH, Sun FY. MicroRNA-365 modulates astrocyte conversion into neuron in adult rat brain after stroke by targeting Pax6. Glia 2018; 66:1346-1362. [PMID: 29451327 PMCID: PMC6001668 DOI: 10.1002/glia.23308] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 01/18/2018] [Accepted: 01/29/2018] [Indexed: 01/01/2023]
Abstract
Reactive astrocytes induced by ischemia can transdifferentiate into mature neurons. This neurogenic potential of astrocytes may have therapeutic value for brain injury. Epigenetic modifications are widely known to involve in developmental and adult neurogenesis. PAX6, a neurogenic fate determinant, contributes to the astrocyte‐to‐neuron conversion. However, it is unclear whether microRNAs (miRs) modulate PAX6‐mediated astrocyte‐to‐neuron conversion. In the present study we used bioinformatic approaches to predict miRs potentially targeting Pax6, and transient middle cerebral artery occlusion (MCAO) to model cerebral ischemic injury in adult rats. These rats were given striatal injection of glial fibrillary acidic protein targeted enhanced green fluorescence protein lentiviral vectors (Lv‐GFAP‐EGFP) to permit cell fate mapping for tracing astrocytes‐derived neurons. We verified that miR‐365 directly targets to the 3′‐UTR of Pax6 by luciferase assay. We found that miR‐365 expression was significantly increased in the ischemic brain. Intraventricular injection of miR‐365 antagomir effectively increased astrocytic PAX6 expression and the number of new mature neurons derived from astrocytes in the ischemic striatum, and reduced neurological deficits as well as cerebral infarct volume. Conversely, miR‐365 agomir reduced PAX6 expression and neurogenesis, and worsened brain injury. Moreover, exogenous overexpression of PAX6 enhanced the astrocyte‐to‐neuron conversion and abolished the effects of miR‐365. Our results demonstrate that increase of miR‐365 in the ischemic brain inhibits astrocyte‐to‐neuron conversion by targeting Pax6, whereas knockdown of miR‐365 enhances PAX6‐mediated neurogenesis from astrocytes and attenuates neuronal injury in the brain after ischemic stroke. Our findings provide a foundation for developing novel therapeutic strategies for brain injury.
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Affiliation(s)
- Jia-Lin Mo
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Qi Liu
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Zeng-Wei Kou
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Kun-Wei Wu
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China.,Institute for Basic Research on Aging and Medicine, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Ping Yang
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Xian-Hua Chen
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Feng-Yan Sun
- Department of Neurobiology and State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China.,Shanghai Key Laboratory of Clinical Geriatric Medicine, Research Center on Aging and Medicine, Shanghai Medical College, Fudan University, Shanghai, 200032, China.,Institute for Basic Research on Aging and Medicine, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, 200032, China
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35
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Verkhratsky A, Trebak M, Perocchi F, Khananshvili D, Sekler I. Crosslink between calcium and sodium signalling. Exp Physiol 2018; 103:157-169. [PMID: 29210126 PMCID: PMC6813793 DOI: 10.1113/ep086534] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 11/24/2017] [Indexed: 12/12/2022]
Abstract
NEW FINDINGS What is the topic of this review? This paper overviews the links between Ca2+ and Na+ signalling in various types of cells. What advances does it highlight? This paper highlights the general importance of ionic signalling and overviews the molecular mechanisms linking Na+ and Ca2+ dynamics. In particular, the narrative focuses on the molecular physiology of plasmalemmal and mitochondrial Na+ -Ca2+ exchangers and plasmalemmal transient receptor potential channels. Functional consequences of Ca2+ and Na+ signalling for co-ordination of neuronal activity with astroglial homeostatic pathways fundamental for synaptic transmission are discussed. ABSTRACT Transmembrane ionic gradients, which are an indispensable feature of life, are used for generation of cytosolic ionic signals that regulate a host of cellular functions. Intracellular signalling mediated by Ca2+ and Na+ is tightly linked through several molecular pathways that generate Ca2+ and Na+ fluxes and are in turn regulated by both ions. Transient receptor potential (TRP) channels bridge endoplasmic reticulum Ca2+ release with generation of Na+ and Ca2+ currents. The plasmalemmal Na+ -Ca2+ exchanger (NCX) flickers between forward and reverse mode to co-ordinate the influx and efflux of both ions with membrane polarization and cytosolic ion concentrations. The mitochondrial calcium uniporter channel (MCU) and mitochondrial Na+ -Ca2+ exchanger (NCLX) mediate Ca2+ entry into and release from this organelle and couple cytosolic Ca2+ and Na+ fluctuations with cellular energetics. Cellular Ca2+ and Na+ signalling controls numerous functional responses and, in the CNS, provides for fast regulation of astroglial homeostatic cascades that are crucial for maintenance of synaptic transmission.
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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
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Fabiana Perocchi
- Gene Center/Department of Biochemistry, Ludwig-Maximilians Universität München, Munich, Germany
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Neuherberg, Germany
| | - Daniel Khananshvili
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Ramat-Aviv, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Faculty of Health Science, Ben-Gurion University, Beer-Sheva, Israel
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36
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Ghirardini E, Wadle SL, Augustin V, Becker J, Brill S, Hammerich J, Seifert G, Stephan J. Expression of functional inhibitory neurotransmitter transporters GlyT1, GAT-1, and GAT-3 by astrocytes of inferior colliculus and hippocampus. Mol Brain 2018; 11:4. [PMID: 29370841 PMCID: PMC5785846 DOI: 10.1186/s13041-018-0346-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/03/2018] [Indexed: 12/18/2022] Open
Abstract
Neuronal inhibition is mediated by glycine and/or GABA. Inferior colliculus (IC) neurons receive glycinergic and GABAergic inputs, whereas inhibition in hippocampus (HC) predominantly relies on GABA. Astrocytes heterogeneously express neurotransmitter transporters and are expected to adapt to the local requirements regarding neurotransmitter homeostasis. Here we analyzed the expression of inhibitory neurotransmitter transporters in IC and HC astrocytes using whole-cell patch-clamp and single-cell reverse transcription-PCR. We show that most astrocytes in both regions expressed functional glycine transporters (GlyTs). Activation of these transporters resulted in an inward current (IGly) that was sensitive to the competitive GlyT1 agonist sarcosine. Astrocytes exhibited transcripts for GlyT1 but not for GlyT2. Glycine did not alter the membrane resistance (RM) arguing for the absence of functional glycine receptors (GlyRs). Thus, IGly was mainly mediated by GlyT1. Similarly, we found expression of functional GABA transporters (GATs) in all IC astrocytes and about half of the HC astrocytes. These transporters mediated an inward current (IGABA) that was sensitive to the competitive GAT-1 and GAT-3 antagonists NO711 and SNAP5114, respectively. Accordingly, transcripts for GAT-1 and GAT-3 were found but not for GAT-2 and BGT-1. Only in hippocampal astrocytes, GABA transiently reduced RM demonstrating the presence of GABAA receptors (GABAARs). However, IGABA was mainly not contaminated by GABAAR-mediated currents as RM changes vanished shortly after GABA application. In both regions, IGABA was stronger than IGly. Furthermore, in HC the IGABA/IGly ratio was larger compared to IC. Taken together, our results demonstrate that astrocytes are heterogeneous across and within distinct brain areas. Furthermore, we could show that the capacity for glycine and GABA uptake varies between both brain regions.
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Affiliation(s)
- Elsa Ghirardini
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.,Department of Medical Biotechnology and Translational Medicine, University of Milan, via Vanvitelli 32, I-20129, Milan, Italy.,Pharmacology and Brain Pathology Lab, Humanitas Clinical and Research Center, via Manzoni 56, I-20089, Rozzano, Italy
| | - Simon L Wadle
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Vanessa Augustin
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Jasmin Becker
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Sina Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Julia Hammerich
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany
| | - Jonathan Stephan
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, D-67663, Kaiserslautern, Germany.
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Rose CR, Felix L, Zeug A, Dietrich D, Reiner A, Henneberger C. Astroglial Glutamate Signaling and Uptake in the Hippocampus. Front Mol Neurosci 2018; 10:451. [PMID: 29386994 PMCID: PMC5776105 DOI: 10.3389/fnmol.2017.00451] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
Astrocytes have long been regarded as essentially unexcitable cells that do not contribute to active signaling and information processing in the brain. Contrary to this classical view, it is now firmly established that astrocytes can specifically respond to glutamate released from neurons. Astrocyte glutamate signaling is initiated upon binding of glutamate to ionotropic and/or metabotropic receptors, which can result in calcium signaling, a major form of glial excitability. Release of so-called gliotransmitters like glutamate, ATP and D-serine from astrocytes in response to activation of glutamate receptors has been demonstrated to modulate various aspects of neuronal function in the hippocampus. In addition to receptors, glutamate binds to high-affinity, sodium-dependent transporters, which results in rapid buffering of synaptically-released glutamate, followed by its removal from the synaptic cleft through uptake into astrocytes. The degree to which astrocytes modulate and control extracellular glutamate levels through glutamate transporters depends on their expression levels and on the ionic driving forces that decrease with ongoing activity. Another major determinant of astrocytic control of glutamate levels could be the precise morphological arrangement of fine perisynaptic processes close to synapses, defining the diffusional distance for glutamate, and the spatial proximity of transporters in relation to the synaptic cleft. In this review, we will present an overview of the mechanisms and physiological role of glutamate-induced ion signaling in astrocytes in the hippocampus as mediated by receptors and transporters. Moreover, we will discuss the relevance of astroglial glutamate uptake for extracellular glutamate homeostasis, focusing on how activity-induced dynamic changes of perisynaptic processes could shape synaptic transmission at glutamatergic synapses.
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Affiliation(s)
- Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Lisa Felix
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Dirk Dietrich
- Department of Neurosurgery, University of Bonn Medical School, Bonn, Germany
| | - Andreas Reiner
- Cellular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany.,German Center for Degenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, United Kingdom
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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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39
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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: 928] [Impact Index Per Article: 154.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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40
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Fried DE, Watson RE, Robson SC, Gulbransen BD. Ammonia modifies enteric neuromuscular transmission through glial γ-aminobutyric acid signaling. Am J Physiol Gastrointest Liver Physiol 2017; 313:G570-G580. [PMID: 28838986 PMCID: PMC5814673 DOI: 10.1152/ajpgi.00154.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 01/31/2023]
Abstract
Impaired gut motility may contribute, at least in part, to the development of systemic hyperammonemia and systemic neurological disorders in inherited metabolic disorders, or in severe liver and renal disease. It is not known whether enteric neurotransmission regulates intestinal luminal and hence systemic ammonia levels by induced changes in motility. Here, we propose and test the hypothesis that ammonia acts through specific enteric circuits to influence gut motility. We tested our hypothesis by recording the effects of ammonia on neuromuscular transmission in tissue samples from mice, pigs, and humans and investigated specific mechanisms using novel mutant mice, selective drugs, cellular imaging, and enzyme-linked immunosorbent assays. Exogenous ammonia increased neurogenic contractions and decreased neurogenic relaxations in segments of mouse, pig, and human intestine. Enteric glial cells responded to ammonia with intracellular Ca2+ responses. Inhibition of glutamine synthetase and the deletion of glial connexin-43 channels in hGFAP::CreERT2+/-/connexin43f/f mice potentiated the effects of ammonia on neuromuscular transmission. The effects of ammonia on neuromuscular transmission were blocked by GABAA receptor antagonists, and ammonia drove substantive GABA release as did the selective pharmacological activation of enteric glia in GFAP::hM3Dq transgenic mice. We propose a novel mechanism whereby local ammonia is operational through GABAergic glial signaling to influence enteric neuromuscular circuits that regulate intestinal motility. Therapeutic manipulation of these mechanisms may benefit a number of neurological, hepatic, and renal disorders manifesting hyperammonemia.NEW & NOTEWORTHY We propose that local circuits in the enteric nervous system sense and regulate intestinal ammonia. We show that ammonia modifies enteric neuromuscular transmission to increase motility in human, pig, and mouse intestine model systems. The mechanisms underlying the effects of ammonia on enteric neurotransmission include GABAergic pathways that are regulated by enteric glial cells. Our new data suggest that myenteric glial cells sense local ammonia and directly modify neurotransmission by releasing GABA.
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Affiliation(s)
- David E. Fried
- 1Neuroscience Program and Department of Physiology,
Michigan State University, East Lansing,
Michigan;
| | - Ralph E. Watson
- 2Department of Medicine, Michigan State
University, East Lansing, Michigan; and
| | - Simon C. Robson
- 3Divisions of Gastroenterology and Transplantation, Department
of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical
School, Boston, Massachusetts
| | - Brian D. Gulbransen
- 1Neuroscience Program and Department of Physiology,
Michigan State University, East Lansing,
Michigan;
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41
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Donadieu M, Le Fur Y, Maarouf A, Gherib S, Ridley B, Pini L, Rapacchi S, Confort-Gouny S, Guye M, Schad LR, Maudsley AA, Pelletier J, Audoin B, Zaaraoui W, Ranjeva JP. Metabolic counterparts of sodium accumulation in multiple sclerosis: A whole brain 23Na-MRI and fast 1H-MRSI study. Mult Scler 2017; 25:39-47. [DOI: 10.1177/1352458517736146] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background: Increase of brain total sodium concentrations (TSC) is present in multiple sclerosis (MS), but its pathological involvement has not been assessed yet. Objective: To determine in vivo the metabolic counterpart of brain sodium accumulation. Materials/methods: Whole brain 23Na-MR imaging and 3D-1H-EPSI data were collected in 21 relapsing-remitting multiple sclerosis (RRMS) patients and 20 volunteers. Metabolites and sodium levels were extracted from several regions of grey matter (GM), normal-appearing white matter (NAWM) and white matter (WM) T2 lesions. Metabolic and ionic levels expressed as Z-scores have been averaged over the different compartments and used to explain sodium accumulations through stepwise regression models. Results: MS patients showed significant 23Na accumulations with lower choline and glutamate–glutamine (Glx) levels in GM; 23Na accumulations with lower N-acetyl aspartate (NAA), Glx levels and higher Myo-Inositol (m-Ins) in NAWM; and higher 23Na, m-Ins levels with lower NAA in WM T2 lesions. Regression models showed associations of TSC increase with reduced NAA in GM, NAWM and T2 lesions, as well as higher total-creatine, and smaller decrease of m-Ins in T2 lesions. GM Glx levels were associated with clinical scores. Conclusion: Increase of TSC in RRMS is mainly related to neuronal mitochondrial dysfunction while dysfunction of neuro-glial interactions within GM is linked to clinical scores.
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Affiliation(s)
- Maxime Donadieu
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France/Siemens Healthineers, Saint-Denis, France
| | - Yann Le Fur
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Adil Maarouf
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France/APHM, Timone University Hospital, Department of Neurology, Marseille, FranceCNRS, CRMBM UMR 7339, Medical School of Marseille, Aix-Marseille University, Marseille, France/AP-HM, CHU Timone, Department of Imaging, CEMEREM, Marseille, France/AP-HM, CHU Timone, Pole de Neurosciences Cliniques, Department of Neurology, Marseille, France
| | - Soraya Gherib
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Ben Ridley
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Lauriane Pini
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Stanislas Rapacchi
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Sylviane Confort-Gouny
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Maxime Guye
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Lothar R Schad
- Computer Assisted Clinical Medicine, Mannheim University Hospital, Heidelberg University, Mannheim, Germany
| | - Andrew A Maudsley
- Department of Radiology, University of Miami School of Medicine, Miami, FL, USA
| | - Jean Pelletier
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France/APHM, Timone University Hospital, Department of Neurology, Marseille, FranceCNRS, CRMBM UMR 7339, Medical School of Marseille, Aix-Marseille University, Marseille, France/AP-HM, CHU Timone, Department of Imaging, CEMEREM, Marseille, France/AP-HM, CHU Timone, Pole de Neurosciences Cliniques, Department of Neurology, Marseille, France
| | - Bertrand Audoin
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France/APHM, Timone University Hospital, Department of Neurology, Marseille, FranceCNRS, CRMBM UMR 7339, Medical School of Marseille, Aix-Marseille University, Marseille, France/AP-HM, CHU Timone, Department of Imaging, CEMEREM, Marseille, France/AP-HM, CHU Timone, Pole de Neurosciences Cliniques, Department of Neurology, Marseille, France
| | - Wafaa Zaaraoui
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
| | - Jean-Philippe Ranjeva
- Aix-Marseille University, CNRS, CRMBM, APHM, Marseille, France/Timone University Hospital, CEMEREM, Marseille, France
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Todd AC, Marx MC, Hulme SR, Bröer S, Billups B. SNAT3-mediated glutamine transport in perisynaptic astrocytesin situis regulated by intracellular sodium. Glia 2017; 65:900-916. [DOI: 10.1002/glia.23133] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/12/2017] [Accepted: 02/08/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Alison C. Todd
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
- Centre for Integrative Physiology, School of Biomedical Sciences; University of Edinburgh; Edinburgh EH8 9XD United Kingdom
| | - Mari-Carmen Marx
- Department of Pharmacology; University of Cambridge; Tennis Court Road Cambridge CB2 1BT United Kingdom
| | - Sarah R. Hulme
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
| | - Stefan Bröer
- Research School of Biology; The Australian National University; Linnaeus Way 134 Canberra ACT 2601 Australia
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
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Astrocyte Sodium Signalling and Panglial Spread of Sodium Signals in Brain White Matter. Neurochem Res 2017; 42:2505-2518. [PMID: 28214986 DOI: 10.1007/s11064-017-2197-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/19/2017] [Accepted: 01/28/2017] [Indexed: 10/20/2022]
Abstract
In brain grey matter, excitatory synaptic transmission activates glutamate uptake into astrocytes, inducing sodium signals which propagate into neighboring astrocytes through gap junctions. These sodium signals have been suggested to serve an important role in neuro-metabolic coupling. So far, it is unknown if astrocytes in white matter-that is in brain regions devoid of synapses-are also able to undergo such intra- and intercellular sodium signalling. In the present study, we have addressed this question by performing quantitative sodium imaging in acute tissue slices of mouse corpus callosum. Focal application of glutamate induced sodium transients in SR101-positive astrocytes. These were largely unaltered in the presence of ionotropic glutamate receptors blockers, but strongly dampened upon pharmacological inhibition of glutamate uptake. Sodium signals induced in individual astrocytes readily spread into neighboring SR101-positive cells with peak amplitudes decaying monoexponentially with distance from the stimulated cell. In addition, spread of sodium was largely unaltered during pharmacological inhibition of purinergic and glutamate receptors, indicating gap junction-mediated, passive diffusion of sodium between astrocytes. Using cell-type-specific, transgenic reporter mice, we found that sodium signals also propagated, albeit less effectively, from astrocytes to neighboring oligodendrocytes and NG2 cells. Again, panglial spread was unaltered with purinergic and glutamate receptors blocked. Taken together, our results demonstrate that activation of sodium-dependent glutamate transporters induces sodium signals in white matter astrocytes, which spread within the astrocyte syncytium. In addition, we found a panglial passage of sodium signals from astrocytes to NG2 cells and oligodendrocytes, indicating functional coupling between these macroglial cells in white matter.
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44
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Gerkau NJ, Rakers C, Petzold GC, Rose CR. Differential effects of energy deprivation on intracellular sodium homeostasis in neurons and astrocytes. J Neurosci Res 2017; 95:2275-2285. [PMID: 28150887 DOI: 10.1002/jnr.23995] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/10/2016] [Accepted: 11/10/2016] [Indexed: 12/11/2022]
Abstract
The maintenance of a low intracellular sodium concentration by the Na+ /K+ -ATPase (NKA) is critical for brain function. In both neurons and glial cells, NKA activity is required to counteract changes in the sodium gradient due to opening of voltage- and ligand-gated channels and/or activation of sodium-dependent secondary active transporters. Because NKA consumes about 50% of cellular ATP, sodium homeostasis is strictly dependent on an intact cellular energy metabolism. Despite the high energetic costs of electrical signaling, neurons do not contain significant energy stores themselves, but rely on a close metabolic interaction with surrounding astrocytes. A disruption of energy supply as observed during focal ischemia causes a rapid drop in ATP in both neurons and astrocytes. There is accumulating evidence that dysregulation of intracellular sodium is an inherent consequence of a reduction in cellular ATP, triggering secondary failure of extra- and intracellular homeostasis of other ions -in particular potassium, calcium, and protons- and thereby promoting excitotoxicity. The characteristics, cellular mechanisms and direct consequences of harmful sodium influx, however, differ between neurons and astrocytes. Moreover, recent work has shown that an intact astrocyte metabolism and sodium homeostasis are critical to maintain the sodium homeostasis of surrounding neurons as well as their capacity to recover from imposed sodium influx. Understanding the mechanisms of sodium increases upon metabolic failure and the differential responses of neurons and glial cells as well as their metabolic interactions will be critical to fully unravel the events causing cellular malfunction, failure and cell death following energy depletion. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Niklas J Gerkau
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany
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45
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Kunisawa K, Kido K, Nakashima N, Matsukura T, Nabeshima T, Hiramatsu M. Betaine attenuates memory impairment after water-immersion restraint stress and is regulated by the GABAergic neuronal system in the hippocampus. Eur J Pharmacol 2017; 796:122-130. [DOI: 10.1016/j.ejphar.2016.12.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 12/03/2016] [Accepted: 12/05/2016] [Indexed: 02/05/2023]
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46
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Abstract
Glycine, besides exerting essential metabolic functions, is an important inhibitory neurotransmitter in caudal areas of the central nervous system and also a positive neuromodulator at excitatory glutamate-mediated synapses. Glial cells provide metabolic support to neurons and modulate synaptic activity. Six transporters belonging to three solute carrier families (SLC6, SLC38, and SLC7) are capable of transporting glycine across the glial plasma membrane. The unique glial glycine-selective transporter GlyT1 (SLC6) is the main regulator of synaptic glycine concentrations, assisted by the neuronal GlyT2. The five additional glycine transporters ATB0,+, SNAT1, SNAT2, SNAT5, and LAT2 display broad amino acid specificity and have differential contributions to glial glycine transport. Glial glycine transporters are divergent in sequence but share a similar architecture displaying the 5 + 5 inverted fold originally characterized in the leucine transporter LeuT. The availability of protein crystals solved at high resolution for prokaryotic and, more recently, eukaryotic homologues of this superfamily has advanced significantly our understanding of the mechanism of glycine transport.
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47
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Rose CR, Ziemens D, Untiet V, Fahlke C. Molecular and cellular physiology of sodium-dependent glutamate transporters. Brain Res Bull 2016; 136:3-16. [PMID: 28040508 DOI: 10.1016/j.brainresbull.2016.12.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 12/20/2016] [Accepted: 12/21/2016] [Indexed: 02/04/2023]
Abstract
Glutamate is the major excitatory transmitter in the vertebrate brain. After its release from presynaptic nerve terminals, it is rapidly taken up by high-affinity sodium-dependent plasma membrane transporters. While both neurons and glial cells express these excitatory amino acid transporters (EAATs), the majority of glutamate uptake is accomplished by astrocytes, which convert synaptically-released glutamate to glutamine or feed it into their own metabolism. Glutamate uptake by astrocytes not only shapes synaptic transmission by regulating the availability of glutamate to postsynaptic neuronal receptors, but also protects neurons from hyper-excitability and subsequent excitotoxic damage. In the present review, we provide an overview of the molecular and cellular characteristics of sodium-dependent glutamate transporters and their associated anion permeation pathways, with a focus on astrocytic glutamate transport. We summarize their functional properties and roles within tripartite synapses under physiological and pathophysiological conditions, exemplifying the intricate interactions and interrelationships between neurons and glial cells in the brain.
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Affiliation(s)
- Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Germany.
| | - Daniel Ziemens
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Germany
| | - Verena Untiet
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Germany
| | - Christoph Fahlke
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, Germany
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48
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Lindberg D, Choi DS. Disruption of Integrated Neuronal and Astrocytic Signaling Contributes to Alcohol Use Disorder. Alcohol Clin Exp Res 2016; 40:2309-2311. [PMID: 27716954 DOI: 10.1111/acer.13227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 08/30/2016] [Indexed: 12/01/2022]
Affiliation(s)
- Daniel Lindberg
- Neurobiology of Disease Program, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Doo-Sup Choi
- Neurobiology of Disease Program, Mayo Clinic College of Medicine, Rochester, Minnesota. .,Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota. .,Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, Rochester, Minnesota.
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49
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Adermark L, Bowers MS. Disentangling the Role of Astrocytes in Alcohol Use Disorder. Alcohol Clin Exp Res 2016; 40:1802-16. [PMID: 27476876 PMCID: PMC5407469 DOI: 10.1111/acer.13168] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 07/02/2016] [Indexed: 01/29/2023]
Abstract
Several laboratories recently identified that astrocytes are critical regulators of addiction machinery. It is now known that astrocyte pathology is a common feature of ethanol (EtOH) exposure in both humans and animal models, as even brief EtOH exposure is sufficient to elicit long-lasting perturbations in astrocyte gene expression, activity, and proliferation. Astrocytes were also recently shown to modulate the motivational properties of EtOH and other strongly reinforcing stimuli. Given the role of astrocytes in regulating glutamate homeostasis, a crucial component of alcohol use disorder (AUD), astrocytes might be an important target for the development of next-generation alcoholism treatments. This review will outline some of the more prominent features displayed by astrocytes, how these properties are influenced by acute and long-term EtOH exposure, and future directions that may help to disentangle astrocytic from neuronal functions in the etiology of AUD.
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Affiliation(s)
- Louise Adermark
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Box 410, SE-405 30 Gothenburg, Sweden
| | - M. Scott Bowers
- Department of Psychiatry, Virginia Commonwealth University, PO Box 980126, Richmond, VA 23298, USA
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, PO Box 980126, Richmond, VA 23298, USA
- Faulk Center for Molecular Therapeutics, Northwestern University; Aptinyx,, Evanston, Il 60201, USA
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50
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Choi M, Ahn S, Yang EJ, Kim H, Chong YH, Kim HS. Hippocampus-based contextual memory alters the morphological characteristics of astrocytes in the dentate gyrus. Mol Brain 2016; 9:72. [PMID: 27460927 PMCID: PMC4962445 DOI: 10.1186/s13041-016-0253-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 07/22/2016] [Indexed: 12/31/2022] Open
Abstract
Astrocytes have been reported to exist in two states, the resting and the reactive states. Morphological changes in the reactive state of astrocytes include an increase in thickness and number of processes, and an increase in the size of the cell body. Molecular changes also occur, such as an increase in the expression of glial fibrillary acidic protein (GFAP). However, the morphological and molecular changes during the process of learning and memory have not been elucidated. In the current study, we subjected Fvb/n mice to contextual fear conditioning, and checked for morphological and molecular changes in astrocytes. 1 h after fear conditioning, type II and type III astrocytes exhibited a unique status with an increased number of processes and decreased GFAP expression which differed from the typical resting or reactive state. In addition, the protein level of excitatory excitatory amino acid transporter 2 (EAAT2) was increased 1 h to 24 h after contextual fear conditioning while EAAT1 did not show any alterations. Connexin 43 (Cx43) protein was found to be increased at 24 h after fear conditioning. These data suggest that hippocampus-based contextual memory process induces changes in the status of astrocytes towards a novel status different from typical resting or reactive states. These morphological and molecular changes may be in line with functional changes.
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Affiliation(s)
- Moonseok Choi
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Sangzin Ahn
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Eun-Jeong Yang
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Hyunju Kim
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea
| | - Young Hae Chong
- Department of Microbiology, School of Medicine, Ewha Womans University, 911-1, Mok-6-dong, Yangcheonku, Seoul, 158-710, Republic of Korea
| | - Hye-Sun Kim
- Department of Pharmacology and Biomedical Sciences, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, 110-799, Seoul, Republic of Korea. .,Seoul National University College of Medicine, Seoul National University Bundang Hospital, Sungnam, 463-707, Republic of Korea. .,Seoul National University College of Medicine, Bundang Hospital, Sungnam, Bundang-Gu, Republic of Korea. .,Neuroscience Research Institute, College of Medicine, Seoul National University, 103 Daehakro, Jongro-gu, Seoul, Republic of Korea.
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