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Garcia JP, Armbruster M, Sommer M, Nunez-Beringer A, Dulla CG. Glutamate uptake is transiently compromised in the perilesional cortex following controlled cortical impact. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.28.610143. [PMID: 39257826 PMCID: PMC11383988 DOI: 10.1101/2024.08.28.610143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Glutamate, the primary excitatory neurotransmitter in the CNS, is regulated by the excitatory amino acid transporters (EAATs) GLT-1 and GLAST. Following traumatic brain injury (TBI), extracellular glutamate levels increase, contributing to excitotoxicity, circuit dysfunction, and morbidity. Increased neuronal glutamate release and compromised astrocyte-mediated uptake contribute to elevated glutamate, but the mechanistic and spatiotemporal underpinnings of these changes are not well established. Using the controlled cortical impact (CCI) model of TBI and iGluSnFR glutamate imaging, we quantified extracellular glutamate dynamics after injury. Three days post-injury, glutamate release was increased, and glutamate uptake and GLT-1 expression were reduced. 7- and 14-days post-injury, glutamate dynamics were comparable between sham and CCI animals. Changes in peak glutamate response were unique to specific cortical layers and proximity to injury. This was likely driven by increases in glutamate release, which was spatially heterogenous, rather than reduced uptake, which was spatially uniform. The astrocyte K + channel, Kir4.1, regulates activity-dependent slowing of glutamate uptake. Surprisingly, Kir4.1 was unchanged after CCI and accordingly, activity-dependent slowing of glutamate uptake was unaltered. This dynamic glutamate dysregulation after TBI underscores a brief period in which disrupted glutamate uptake may contribute to dysfunction and highlights a potential therapeutic window to restore glutamate homeostasis.
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2
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Vilca SJ, Margetts AV, Höglund L, Fleites I, Bystrom LL, Pollock TA, Bourgain-Guglielmetti F, Wahlestedt C, Tuesta LM. Microglia contribute to methamphetamine reinforcement and reflect persistent transcriptional and morphological adaptations to the drug. Brain Behav Immun 2024; 120:339-351. [PMID: 38838836 PMCID: PMC11269013 DOI: 10.1016/j.bbi.2024.05.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 05/27/2024] [Accepted: 05/29/2024] [Indexed: 06/07/2024] Open
Abstract
Methamphetamine use disorder (MUD) is a chronic, relapsing disease that is characterized by repeated drug use despite negative consequences and for which there are currently no FDA-approved cessation therapeutics. Repeated methamphetamine (METH) use induces long-term gene expression changes in brain regions associated with reward processing and drug-seeking behavior, and recent evidence suggests that methamphetamine-induced neuroinflammation may also shape behavioral and molecular responses to the drug. Microglia, the resident immune cells in the brain, are principal drivers of neuroinflammatory responses and contribute to the pathophysiology of substance use disorders. Here, we investigated transcriptional and morphological changes in dorsal striatal microglia in response to methamphetamine-taking and during methamphetamine abstinence, as well as their functional contribution to drug-taking behavior. We show that methamphetamine self-administration induces transcriptional changes associated with protein folding, mRNA processing, immune signaling, and neurotransmission in dorsal striatal microglia. Importantly, many of these transcriptional changes persist through abstinence, a finding supported by morphological analyses. Functionally, we report that microglial ablation increases methamphetamine-taking, possibly involving neuroimmune and neurotransmitter regulation. In contrast, microglial depletion during abstinence does not alter methamphetamine-seeking. Taken together, these results suggest that methamphetamine induces both short and long-term changes in dorsal striatal microglia that contribute to altered drug-taking behavior and may provide valuable insights into the pathophysiology of MUD.
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Affiliation(s)
- Samara J Vilca
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Alexander V Margetts
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Leon Höglund
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Isabella Fleites
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Lauren L Bystrom
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Tate A Pollock
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Florence Bourgain-Guglielmetti
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Claes Wahlestedt
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, United States
| | - Luis M Tuesta
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136, United States; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, United States.
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3
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Boucher ML, Conley G, Morriss NJ, Ospina-Mora S, Qiu J, Mannix R, Meehan WP. Time-Dependent Long-Term Effect of Memantine following Repetitive Mild Traumatic Brain Injury. J Neurotrauma 2024; 41:e1736-e1758. [PMID: 38666723 DOI: 10.1089/neu.2023.0423] [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] [Indexed: 05/16/2024] Open
Abstract
Repetitive mild traumatic brain injury (rmTBI, e.g., sports concussions) may be associated with both acute and chronic symptoms and neurological changes. Despite the common occurrence of these injuries, therapeutic strategies are limited. One potentially promising approach is N-methyl-D-aspartate receptor (NMDAR) blockade to alleviate the effects of post-injury glutamatergic excitotoxicity. Initial pre-clinical work using the NMDAR antagonist, memantine, suggests that immediate treatment following rmTBI improves a variety of acute outcomes. It remains unclear (1) whether acute memantine treatment has long-term benefits and (2) whether delayed treatment following rmTBI is beneficial, which are both clinically relevant concerns. To test this, animals were subjected to rmTBI via a weight drop model with rotational acceleration (five hits in 5 days) and randomized to memantine treatment immediately, 3 months, or 6 months post-injury, with a treatment duration of one month. Behavioral outcomes were assessed at 1, 4, and 7 months post-injury. Neuropathological outcomes were characterized at 7 months post-injury. We observed chronic changes in behavior (anxiety-like behavior, motor coordination, spatial learning, and memory), as well as neuroinflammation (microglia, astrocytes) and tau phosphorylation (T231). Memantine treatment, either immediately or 6 months post-injury, appears to confer greater rescue of neuroinflammatory changes (microglia) than vehicle or treatment at the 3-month time point. Although memantine is already being prescribed chronically to address persistent symptoms associated with rmTBI, this study represents the first evidence of which we are aware to suggest a small but durable effect of memantine treatment in mild, concussive injuries. This effect suggests that memantine, although potentially beneficial, is insufficient to treat all aspects of rmTBI alone and should be combined with other therapeutic agents in a multi-therapy approach, with attention given to the timing of treatment.
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Affiliation(s)
- Masen L Boucher
- Division of Emergency Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | | | - Nicholas J Morriss
- University of Rochester School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA
| | | | - Jianhua Qiu
- Division of Emergency Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Rebekah Mannix
- Division of Emergency Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - William P Meehan
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Division of Sports Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- The Micheli Center for Sports Injury Prevention, Waltham, Massachusetts, USA
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4
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Vilca SJ, Margetts AV, Fleites I, Wahlestedt C, Tuesta LM. Microglia contribute to methamphetamine reinforcement and reflect persistent transcriptional and morphological adaptations to the drug. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.19.563168. [PMID: 37961443 PMCID: PMC10634674 DOI: 10.1101/2023.10.19.563168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Methamphetamine use disorder (MUD) is a chronic, relapsing disease that is characterized by repeated drug use despite negative consequences and for which there are currently no FDA-approved cessation therapeutics. Repeated methamphetamine (METH) use induces long-term gene expression changes in brain regions associated with reward processing and drug-seeking behavior, and recent evidence suggests that methamphetamine-induced neuroinflammation may also shape behavioral and molecular responses to the drug. Microglia, the resident immune cells in the brain, are principal drivers of neuroinflammatory responses and contribute to the pathophysiology of substance use disorders. Here, we investigated transcriptional and morphological changes in dorsal striatal microglia in response to methamphetamine-taking and during methamphetamine abstinence, as well as their functional contribution to drug-taking behavior. We show that methamphetamine self-administration induces transcriptional changes associated with protein folding, mRNA processing, immune signaling, and neurotransmission in dorsal striatal microglia. Importantly, many of these transcriptional changes persist through abstinence, a finding supported by morphological analyses. Functionally, we report that microglial ablation increases methamphetamine-taking, possibly involving neuroimmune and neurotransmitter regulation, and that post-methamphetamine microglial repopulation attenuates drug-seeking following a 21-day period of abstinence. In contrast, microglial depletion during abstinence did not alter methamphetamine-seeking. Taken together, these results suggest that methamphetamine induces both short and long-term changes in dorsal striatal microglia that contribute to altered drug-taking behavior and may provide valuable insights into the pathophysiology of MUD.
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Affiliation(s)
- Samara J. Vilca
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136
- Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Alexander V. Margetts
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136
- Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Isabella Fleites
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136
- Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Claes Wahlestedt
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136
- Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Luis M. Tuesta
- Department of Psychiatry & Behavioral Sciences, University of Miami Miller School of Medicine, Miami, FL 33136
- Center for Therapeutic Innovation, University of Miami Miller School of Medicine, Miami, FL 33136
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
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5
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Caruso G, Di Pietro L, Caraci F. Gap Junctions and Connexins in Microglia-Related Oxidative Stress and Neuroinflammation: Perspectives for Drug Discovery. Biomolecules 2023; 13:biom13030505. [PMID: 36979440 PMCID: PMC10046203 DOI: 10.3390/biom13030505] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/28/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Microglia represent the immune system of the brain. Their role is central in two phenomena, neuroinflammation and oxidative stress, which are at the roots of different pathologies related to the central nervous system (CNS). In order to maintain the homeostasis of the brain and re-establish the equilibrium after a threatening imbalance, microglia communicate with each other and other cells within the CNS by receiving specific signals through membrane-bound receptors and then releasing neurotrophic factors into either the extracellular milieu or directly into the cytoplasm of nearby cells, such as astrocytes and neurons. These last two mechanisms rely on the activity of protein structures that enable the formation of channels in the membrane, namely, connexins and pannexins, that group and form gap junctions, hemichannels, and pannexons. These channels allow the release of gliotransmitters, such as adenosine triphosphate (ATP) and glutamate, together with calcium ion (Ca2+), that seem to play a pivotal role in inter-cellular communication. The aim of the present review is focused on the physiology of channel protein complexes and their contribution to neuroinflammatory and oxidative stress-related phenomena, which play a central role in neurodegenerative disorders. We will then discuss how pharmacological modulation of these channels can impact neuroinflammatory phenomena and hypothesize that currently available nutraceuticals, such as carnosine and N-acetylcysteine, can modulate the activity of connexins and pannexins in microglial cells and reduce oxidative stress in neurodegenerative disorders.
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Affiliation(s)
- Giuseppe Caruso
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
- Correspondence: ; Tel.: +39-0957385036
| | - Lucia Di Pietro
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Scuola Superiore di Catania, University of Catania, 95123 Catania, Italy
| | - Filippo Caraci
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
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6
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Sen ZD, Danyeli LV, Woelfer M, Lamers F, Wagner G, Sobanski T, Walter M. Linking atypical depression and insulin resistance-related disorders via low-grade chronic inflammation: Integrating the phenotypic, molecular and neuroanatomical dimensions. Brain Behav Immun 2021; 93:335-352. [PMID: 33359233 DOI: 10.1016/j.bbi.2020.12.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 12/11/2020] [Accepted: 12/17/2020] [Indexed: 12/13/2022] Open
Abstract
Insulin resistance (IR) and related disorders, such as T2DM, increase the risk of major depressive disorder (MDD) and vice versa. Current evidence indicates that psychological stress and overeating can induce chronic low-grade inflammation that can interfere with glutamate metabolism in MDD as well as insulin signaling, particularly in the atypical subtype. Here we first review the interactive role of inflammatory processes in the development of MDD, IR and related metabolic disorders. Next, we describe the role of the anterior cingulate cortex in the pathophysiology of MDD and IR-related disorders. Furthermore, we outline how specific clinical features of atypical depression, such as hyperphagia, are more associated with inflammation and IR-related disorders. Finally, we examine the regional specificity of the effects of inflammation on the brain that show an overlap with the functional and morphometric brain patterns activated in MDD and IR-related disorders.
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Affiliation(s)
- Zümrüt Duygu Sen
- Department of Psychiatry and Psychotherapy, University Tuebingen, Calwerstraße 14, 72076 Tuebingen, Germany; Department of Psychiatry and Psychotherapy, Jena University Hospital, Philosophenweg 3, 07743 Jena, Germany
| | - Lena Vera Danyeli
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Philosophenweg 3, 07743 Jena, Germany; Clinical Affective Neuroimaging Laboratory (CANLAB), Leipziger Str. 44, Building 65, 39120 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Marie Woelfer
- Clinical Affective Neuroimaging Laboratory (CANLAB), Leipziger Str. 44, Building 65, 39120 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany
| | - Femke Lamers
- Department of Psychiatry, Amsterdam UMC, Vrije Universiteit, Oldenaller 1, 1081 HJ Amsterdam, the Netherlands
| | - Gerd Wagner
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Philosophenweg 3, 07743 Jena, Germany
| | - Thomas Sobanski
- Department of Psychiatry, Psychotherapy and Psychosomatic Medicine, Thueringen-Kliniken "Georgius Agricola" GmbH, Rainweg 68, 07318 Saalfeld, Germany
| | - Martin Walter
- Department of Psychiatry and Psychotherapy, University Tuebingen, Calwerstraße 14, 72076 Tuebingen, Germany; Department of Psychiatry and Psychotherapy, Jena University Hospital, Philosophenweg 3, 07743 Jena, Germany; Clinical Affective Neuroimaging Laboratory (CANLAB), Leipziger Str. 44, Building 65, 39120 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestr. 6, 39118 Magdeburg, Germany.
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7
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Shi AC, Rohlwink U, Scafidi S, Kannan S. Microglial Metabolism After Pediatric Traumatic Brain Injury - Overlooked Bystanders or Active Participants? Front Neurol 2021; 11:626999. [PMID: 33569038 PMCID: PMC7868439 DOI: 10.3389/fneur.2020.626999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 12/23/2020] [Indexed: 12/14/2022] Open
Abstract
Microglia play an integral role in brain development but are also crucial for repair and recovery after traumatic brain injury (TBI). TBI induces an intense innate immune response in the immature, developing brain that is associated with acute and chronic changes in microglial function. These changes contribute to long-lasting consequences on development, neurologic function, and behavior. Although alterations in glucose metabolism are well-described after TBI, the bulk of the data is focused on metabolic alterations in astrocytes and neurons. To date, the interplay between alterations in intracellular metabolic pathways in microglia and the innate immune response in the brain following an injury is not well-studied. In this review, we broadly discuss the microglial responses after TBI. In addition, we highlight reported metabolic alterations in microglia and macrophages, and provide perspective on how changes in glucose, fatty acid, and amino acid metabolism can influence and modulate the microglial phenotype and response to injury.
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Affiliation(s)
- Aria C Shi
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ursula Rohlwink
- Neuroscience Institute and Division of Neurosurgery, University of Cape Town, Cape Town, South Africa.,The Francis Crick Institute, London, United Kingdom
| | - Susanna Scafidi
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sujatha Kannan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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8
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Revisiting Traumatic Brain Injury: From Molecular Mechanisms to Therapeutic Interventions. Biomedicines 2020; 8:biomedicines8100389. [PMID: 33003373 PMCID: PMC7601301 DOI: 10.3390/biomedicines8100389] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 12/15/2022] Open
Abstract
Studying the complex molecular mechanisms involved in traumatic brain injury (TBI) is crucial for developing new therapies for TBI. Current treatments for TBI are primarily focused on patient stabilization and symptom mitigation. However, the field lacks defined therapies to prevent cell death, oxidative stress, and inflammatory cascades which lead to chronic pathology. Little can be done to treat the mechanical damage that occurs during the primary insult of a TBI; however, secondary injury mechanisms, such as inflammation, blood-brain barrier (BBB) breakdown, edema formation, excitotoxicity, oxidative stress, and cell death, can be targeted by therapeutic interventions. Elucidating the many mechanisms underlying secondary injury and studying targets of neuroprotective therapeutic agents is critical for developing new treatments. Therefore, we present a review on the molecular events following TBI from inflammation to programmed cell death and discuss current research and the latest therapeutic strategies to help understand TBI-mediated secondary injury.
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9
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Fatoba O, Itokazu T, Yamashita T. Microglia as therapeutic target in central nervous system disorders. J Pharmacol Sci 2020; 144:102-118. [PMID: 32921391 DOI: 10.1016/j.jphs.2020.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/19/2020] [Accepted: 07/07/2020] [Indexed: 12/17/2022] Open
Abstract
Chronic microglial activation is associated with the pathogenesis of several CNS disorders. Microglia show phenotypic diversity and functional complexity in diseased CNS. Thus, understanding the pathology-specific heterogeneity of microglial behavior is crucial for the future development of microglia-modulating therapy for variety of CNS disorders. This review summarizes up-to-date knowledge on how microglia contribute to CNS homeostasis during development and throughout adulthood. We discuss the heterogeneity of microglial phenotypes in the context of CNS disorders with an emphasis on neurodegenerative diseases, demyelinating diseases, CNS trauma, and epilepsy. We conclude this review with a discussion about the disease-specific heterogeneity of microglial function and how it could be exploited for therapeutic intervention.
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Affiliation(s)
- Oluwaseun Fatoba
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI-Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | - Takahide Itokazu
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; WPI-Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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10
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Iovino L, Tremblay ME, Civiero L. Glutamate-induced excitotoxicity in Parkinson's disease: The role of glial cells. J Pharmacol Sci 2020; 144:151-164. [PMID: 32807662 DOI: 10.1016/j.jphs.2020.07.011] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/30/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system. Glutamate transmission efficiency depends on the correct functionality and expression of a plethora of receptors and transporters, located both on neurons and glial cells. Of note, glutamate reuptake by dedicated transporters prevents its accumulation at the synapse as well as non-physiological spillover. Indeed, extracellular glutamate increase causes aberrant synaptic signaling leading to neuronal excitotoxicity and death. Moreover, extrasynaptic glutamate diffusion is strongly associated with glia reaction and neuroinflammation. Glutamate-induced excitotoxicity is mainly linked to an impaired ability of glial cells to reuptake and respond to glutamate, then this is considered a common hallmark in many neurodegenerative diseases, including Parkinson's disease (PD). In this review, we discuss the function of astrocytes and microglia in glutamate homeostasis, focusing on how glial dysfunction causes glutamate-induced excitotoxicity leading to neurodegeneration in PD.
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Affiliation(s)
- L Iovino
- Department of Biology, University of Padova, Italy
| | - M E Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, Canada
| | - L Civiero
- Department of Biology, University of Padova, Italy; IRCCS San Camillo Hospital, Venice, Italy.
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11
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O'Reilly ML, Tom VJ. Neuroimmune System as a Driving Force for Plasticity Following CNS Injury. Front Cell Neurosci 2020; 14:187. [PMID: 32792908 PMCID: PMC7390932 DOI: 10.3389/fncel.2020.00187] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/29/2020] [Indexed: 12/15/2022] Open
Abstract
Following an injury to the central nervous system (CNS), spontaneous plasticity is observed throughout the neuraxis and affects multiple key circuits. Much of this spontaneous plasticity can elicit beneficial and deleterious functional outcomes, depending on the context of plasticity and circuit affected. Injury-induced activation of the neuroimmune system has been proposed to be a major factor in driving this plasticity, as neuroimmune and inflammatory factors have been shown to influence cellular, synaptic, structural, and anatomical plasticity. Here, we will review the mechanisms through which the neuroimmune system mediates plasticity after CNS injury. Understanding the role of specific neuroimmune factors in driving adaptive and maladaptive plasticity may offer valuable therapeutic insight into how to promote adaptive plasticity and/or diminish maladaptive plasticity, respectively.
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Affiliation(s)
- Micaela L O'Reilly
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Veronica J Tom
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, United States
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12
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Victor TR, Tsirka SE. Microglial contributions to aberrant neurogenesis and pathophysiology of epilepsy. NEUROIMMUNOLOGY AND NEUROINFLAMMATION 2020; 7:234-247. [PMID: 33154976 PMCID: PMC7641338 DOI: 10.20517/2347-8659.2020.02] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microglia are dynamic cells that constitute the brain's innate immune system. Recently, research has demonstrated microglial roles beyond immunity, which include homeostatic roles in the central nervous system. The function of microglia is an active area of study, with insights into changes in neurogenesis and synaptic pruning being discovered in both health and disease. In epilepsy, activated microglia contribute to several changes that occur during epileptogenesis. In this review, we focus on the effects of microglia on neurogenesis and synaptic pruning, and discuss the current state of anti-seizure drugs and how they affect microglia during these processes. Our understanding of the role of microglia post-seizure is still limited and may be pivotal in recognizing new therapeutic targets for seizure intervention.
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Affiliation(s)
- Tanya R Victor
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Stella E Tsirka
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
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13
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Robinson RR, Dietz AK, Maroof AM, Asmis R, Forsthuber TG. The role of glial-neuronal metabolic cooperation in modulating progression of multiple sclerosis and neuropathic pain. Immunotherapy 2019; 11:129-147. [PMID: 30730270 DOI: 10.2217/imt-2018-0153] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
While the etiology of multiple sclerosis (MS) remains unclear, research from the clinic and preclinical models identified the essential role of inflammation and demyelination in the pathogenesis of MS. Current treatments focused on anti-inflammatory processes are effective against acute episodes and relapsing-remitting MS, but patients still move on to develop secondary progressive MS. MS progression is associated with activation of microglia and astrocytes, and importantly, metabolic dysfunction leading to neuronal death. Neuronal death also contributes to chronic neuropathic pain. Metabolic support of neurons by glia may play central roles in preventing progression of MS and chronic neuropathic pain. Here, we review mechanisms of metabolic cooperation between glia and neurons and outline future perspectives exploring metabolic support of neurons by glia.
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Affiliation(s)
- Rachel R Robinson
- Department of Biology, University of Texas at San Antonio, TX 78249, USA
| | - Alina K Dietz
- Department of Biology, University of Texas at San Antonio, TX 78249, USA
| | - Asif M Maroof
- Department of Biology, University of Texas at San Antonio, TX 78249, USA
| | - Reto Asmis
- Department of Internal Medicine, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
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14
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Magi S, Piccirillo S, Amoroso S, Lariccia V. Excitatory Amino Acid Transporters (EAATs): Glutamate Transport and Beyond. Int J Mol Sci 2019; 20:ijms20225674. [PMID: 31766111 PMCID: PMC6888595 DOI: 10.3390/ijms20225674] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/08/2019] [Accepted: 11/10/2019] [Indexed: 01/02/2023] Open
Abstract
Na+-dependent excitatory amino acid transporters (EAATs) are the major transport mechanisms for extracellular glutamate removal in the central nervous system (CNS). The primary function assigned to EAATs is the maintenance of low extracellular glutamate levels, thus allowing glutamate to be used as a signaling molecule in the brain and to avoid excitotoxicity. However, glutamate has other recognized functions. For instance, it is a key anaplerotic substrate for the tricarboxylic acid (TCA) cycle, as it can be converted to α-ketoglutarate by transaminases or glutamate dehydrogenase. Furthermore, glutamate is a precursor of the main antioxidant glutathione, which plays a pivotal role in preventing oxidative cell death. Therefore, glutamate signaling/use is at the crossroad of multiple metabolic pathways and accordingly, it can influence a plethora of cell functions, both in health and disease. Here, we provide an overview of the main functions of glutamate and its transport systems, analyzing its role as a neurotransmitter and at the same time, the possible metabolic fates it can undergo in the intracellular milieu. Specifically, the metabolic role of glutamate and the molecular machinery proposed to metabolically support its transport will be further analyzed.
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15
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What Do Microglia Really Do in Healthy Adult Brain? Cells 2019; 8:cells8101293. [PMID: 31652490 PMCID: PMC6829860 DOI: 10.3390/cells8101293] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 12/27/2022] Open
Abstract
Microglia originate from yolk sac-primitive macrophages and auto-proliferate into adulthood without replacement by bone marrow-derived circulating cells. In inflammation, stroke, aging, or infection, microglia have been shown to contribute to brain pathology in both deleterious and beneficial ways, which have been studied extensively. However, less is known about their role in the healthy adult brain. Astrocytes and oligodendrocytes are widely accepted to strongly contribute to the maintenance of brain homeostasis and to modulate neuronal function. On the other hand, contribution of microglia to cognition and behavior is only beginning to be understood. The ability to probe their function has become possible using microglial depletion assays and conditional mutants. Studies have shown that the absence of microglia results in cognitive and learning deficits in rodents during development, but this effect is less pronounced in adults. However, evidence suggests that microglia play a role in cognition and learning in adulthood and, at a cellular level, may modulate adult neurogenesis. This review presents the case for repositioning microglia as key contributors to the maintenance of homeostasis and cognitive processes in the healthy adult brain, in addition to their classical role as sentinels coordinating the neuroinflammatory response to tissue damage and disease.
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16
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McGuire JL, Ngwenya LB, McCullumsmith RE. Neurotransmitter changes after traumatic brain injury: an update for new treatment strategies. Mol Psychiatry 2019; 24:995-1012. [PMID: 30214042 DOI: 10.1038/s41380-018-0239-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 12/12/2022]
Abstract
Traumatic brain injury (TBI) is a pervasive problem in the United States and worldwide, as the number of diagnosed individuals is increasing yearly and there are no efficacious therapeutic interventions. A large number of patients suffer with cognitive disabilities and psychiatric conditions after TBI, especially anxiety and depression. The constellation of post-injury cognitive and behavioral symptoms suggest permanent effects of injury on neurotransmission. Guided in part by preclinical studies, clinical trials have focused on high-yield pathophysiologic mechanisms, including protein aggregation, inflammation, metabolic disruption, cell generation, physiology, and alterations in neurotransmitter signaling. Despite successful treatment of experimental TBI in animal models, clinical studies based on these findings have failed to translate to humans. The current international effort to reshape TBI research is focusing on redefining the taxonomy and characterization of TBI. In addition, as the next round of clinical trials is pending, there is a pressing need to consider what the field has learned over the past two decades of research, and how we can best capitalize on this knowledge to inform the hypotheses for future innovations. Thus, it is critically important to extend our understanding of the pathophysiology of TBI, particularly to mechanisms that are associated with recovery versus development of chronic symptoms. In this review, we focus on the pathology of neurotransmission after TBI, reflecting on what has been learned from both the preclinical and clinical studies, and we discuss new directions and opportunities for future work.
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Affiliation(s)
- Jennifer L McGuire
- Department of Neurosurgery, University of Cincinnati, Cincinnati, OH, USA.
| | - Laura B Ngwenya
- Department of Neurosurgery, University of Cincinnati, Cincinnati, OH, USA.,Department of Neurology and Rehabilitation Medicine, University of Cincinnati, Cincinnati, OH, USA.,Neurotrauma Center, University of Cincinnati Gardner Neuroscience Institute, Cincinnati, OH, 45219, USA
| | - Robert E McCullumsmith
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, USA.,Department of Psychiatry, Cincinnati Veterans Administration Medical Center, Cincinnati, OH, USA
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17
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Magi S, Piccirillo S, Amoroso S. The dual face of glutamate: from a neurotoxin to a potential survival factor-metabolic implications in health and disease. Cell Mol Life Sci 2019; 76:1473-1488. [PMID: 30599069 PMCID: PMC11105246 DOI: 10.1007/s00018-018-3002-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/12/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022]
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system. Beyond this function, glutamate also plays a key role in intermediary metabolism in all organs and tissues, linking carbohydrate and amino acid metabolism via the tricarboxylic acid cycle. Under both physiological and pathological conditions, we have recently found that the ability of glutamate to fuel cell metabolism selectively relies on the activity of two main transporters: the sodium-calcium exchanger (NCX) and the sodium-dependent excitatory amino-acid transporters (EAATs). In ischemic settings, when glutamate is administered at the onset of the reoxygenation phase, the coordinate activity of EAAT and NCX allows glutamate to improve cell viability by stimulating ATP production. So far, this phenomenon has been observed in both cardiac and neuronal models. In this review, we focus on the most recent findings exploring the unusual activity of glutamate as a potential survival factor in different settings.
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Affiliation(s)
- Simona Magi
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy.
| | - Silvia Piccirillo
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
| | - Salvatore Amoroso
- Department of Biomedical Sciences and Public Health, School of Medicine, University "Politecnica delle Marche", Via Tronto 10/A, 60126, Ancona, Italy
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18
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Hagos FT, Adams SM, Poloyac SM, Kochanek PM, Horvat CM, Clark RSB, Empey PE. Membrane transporters in traumatic brain injury: Pathological, pharmacotherapeutic, and developmental implications. Exp Neurol 2019; 317:10-21. [PMID: 30797827 DOI: 10.1016/j.expneurol.2019.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 02/12/2019] [Accepted: 02/20/2019] [Indexed: 12/12/2022]
Abstract
Membrane transporters regulate the trafficking of endogenous and exogenous molecules across biological barriers and within the neurovascular unit. In traumatic brain injury (TBI), they moderate the dynamic movement of therapeutic drugs and injury mediators among neurons, endothelial cells and glial cells, thereby becoming important determinants of pathogenesis and effective pharmacotherapy after TBI. There are three ways transporters may impact outcomes in TBI. First, transporters likely play a key role in the clearance of injury mediators. Second, genetic association studies suggest transporters may be important in the transition of TBI from acute brain injury to a chronic neurological disease. Third, transporters dynamically control the brain penetration and efflux of many drugs and their distribution within and elimination from the brain, contributing to pharmacoresistance and possibly in some cases pharmacosensitivity. Understanding the nature of drugs or candidate drugs in development with respect to whether they are a transporter substrate or inhibitor is relevant to understand whether they distribute to their target in sufficient concentrations. Emerging data provide evidence of altered expression and function of transporters in humans after TBI. Genetic variability in expression and/or function of key transporters adds an additional dynamic, as shown in recent clinical studies. In this review, evidence supporting the role of individual membrane transporters in TBI are discussed as well as novel strategies for their modulation as possible therapeutic targets. Since data specifically targeting pediatric TBI are sparse, this review relies mainly on experimental studies using adult animals and clinical studies in adult patients.
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Affiliation(s)
- Fanuel T Hagos
- Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, PA, United States of America
| | - Solomon M Adams
- Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, PA, United States of America
| | - Samuel M Poloyac
- Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, PA, United States of America; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States of America
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States of America; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America; UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, United States of America
| | - Christopher M Horvat
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States of America; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America; UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, United States of America
| | - Robert S B Clark
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States of America; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States of America; UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, United States of America.
| | - Philip E Empey
- Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, PA, United States of America; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States of America.
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19
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Kumar RG, Breslin KB, Ritter AC, Conley YP, Wagner AK. Variability with Astroglial Glutamate Transport Genetics Is Associated with Increased Risk for Post-Traumatic Seizures. J Neurotrauma 2019; 36:230-238. [PMID: 29999457 PMCID: PMC6338569 DOI: 10.1089/neu.2018.5632] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Excitotoxicity contributes to epileptogenesis after severe traumatic brain injury (sTBI). Demographic and clinical risk factors for post-traumatic seizures (PTS) have been identified, but genetic risk remains largely unknown. Thus, we investigated whether genetic variation in astroglial glutamate transporter genes is associated with accelerated epileptogenesis and PTS risk after sTBI. Adults (n = 267) 18-75 years old were assessed over a three-year period post-TBI. Single nucleotide polymorphisms (SNPs) throughout the SLC1A2 and SLC1A3 genes were assayed. Kaplan-Meier estimates and log-rank statistics were used to compare seizure frequencies by genotype. Multivariate Cox proportional hazards regression was used to estimate hazard ratios (HRs) for genotypes significant in Kaplan-Meier analyses. Thirty-nine tagging SNPs were examined (SLC1A2: n = 21, SLC1A3: n = 18). PTS developed in 57 (21.4%) individuals. Of those with PTS, n = 20 (35.7%) had an immediate/early seizure within the first seven days, and n = 36 (64.3%) had a late seizure occurring between eight days and three years post-TBI. When adjusting for multiple comparisons, rs4869682 genotypes (SLC1A3, GG vs. T-carriers) were associated with time to first seizure (p = 0.003). Median time until first seizure was 20.4 days for individuals with a GG genotype and 44.8 days for T-carriers. After adjusting for covariates, rs4869682 GG-homozygotes had a 2.05 times increased PTS risk versus T-carriers (aHR = 2.08, 95% confidence interval: 1.20, 3.62, p = 0.009). Variation within SLC1A3 is associated with accelerated epileptogenesis and clinical PTS development after sTBI. Future studies should validate these findings and examine how genetic variation at rs4869682 may be a target for PTS prevention and treatment.
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Affiliation(s)
- Raj G. Kumar
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Kristen B. Breslin
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Anne C. Ritter
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Yvette P. Conley
- School of Nursing, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Amy K. Wagner
- Department of Physical Medicine and Rehabilitation, University of Pittsburgh, Pittsburgh, Pennsylvania
- Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, Pennsylvania
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
- Department of Neuroscience, and University of Pittsburgh, Pittsburgh, Pennsylvania
- Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, Pennsylvania
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20
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Ye JL, Gao CQ, Li XG, Jin CL, Wang D, Shu G, Wang WC, Kong XF, Yao K, Yan HC, Wang XQ. EAAT3 promotes amino acid transport and proliferation of porcine intestinal epithelial cells. Oncotarget 2018; 7:38681-38692. [PMID: 27231847 PMCID: PMC5122420 DOI: 10.18632/oncotarget.9583] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/29/2016] [Indexed: 12/11/2022] Open
Abstract
Excitatory amino acid transporter 3 (EAAT3, encoded by SLC1A1) is an epithelial type high-affinity anionic amino acid transporter, and glutamate is the major oxidative fuel for intestinal epithelial cells. This study investigated the effects of EAAT3 on amino acid transport and cell proliferation through activation of the mammalian target of the rapamycin (mTOR) pathway in porcine jejunal epithelial cells (IPEC-J2). Anionic amino acid and cystine (Cys) transport were increased (P<0.05) by EAAT3 overexpression and decreased (P<0.05) by EAAT3 knockdown rather than other amino acids. MTT and cell counting assays suggested that IPEC-J2 cell proliferation increased (P<0.05) with EAAT3 overexpression. Phosphorylation of mTOR (Ser2448), ribosomal protein S6 kinase-1 (S6K1, Thr389) and eukaryotic initiation factor 4E-binding protein-1 (4EBP1, Thr70) was increased by EAAT3 overexpression and decreased by EAAT3 knockdown (P<0.05), as were levels of activating transcription factor 4 (ATF4) and cystine/glutamate antiporter (xCT) (P<0.05). Our results demonstrate for the first time that EAAT3 facilitates anionic amino acid transport and activates the mTOR pathway, promoting Cys transport and IPEC-J2 cell proliferation.
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Affiliation(s)
- Jin-Ling Ye
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Chun-Qi Gao
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Xiang-Guang Li
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Cheng-Long Jin
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Dan Wang
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Gang Shu
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Wen-Ce Wang
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Xiang-Feng Kong
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan Province, China
| | - Kang Yao
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan Province, China
| | - Hui-Chao Yan
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
| | - Xiu-Qi Wang
- College of Animal Science, South China Agricultural University/National Engineering Research Center for Breeding Swine Industry, Guangzhou, Guangdong Province, China
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21
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Glutamine Synthetase: Localization Dictates Outcome. Genes (Basel) 2018; 9:genes9020108. [PMID: 29463059 PMCID: PMC5852604 DOI: 10.3390/genes9020108] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 01/03/2023] Open
Abstract
Glutamine synthetase (GS) is the adenosine triphosphate (ATP)-dependent enzyme that catalyses the synthesis of glutamine by condensing ammonium to glutamate. In the circulatory system, glutamine carries ammonia from muscle and brain to the kidney and liver. In brain reduction of GS activity has been suggested as a mechanism mediating neurotoxicity in neurodegenerative disorders. In cancer, the delicate balance between glutamine synthesis and catabolism is a critical event. In vitro evidence, confirmed in vivo in some cases, suggests that reduced GS activity in cancer cells associates with a more invasive and aggressive phenotype. However, GS is known to be highly expressed in cells of the tumor microenvironment, such as fibroblasts, adipocytes and immune cells, and their ability to synthesize glutamine is responsible for the acquisition of protumoral phenotypes. This has opened a new window into the complex scenario of the tumor microenvironment, in which the balance of glutamine consumption versus glutamine synthesis influences cellular function. Since GS expression responds to glutamine starvation, a lower glutamine synthesizing power due to the absence of GS in cancer cells might apply a metabolic pressure on stromal cells. This event might push stroma towards a GS-high/protumoral phenotype. When referred to stromal cells, GS expression might acquire a ‘bad’ significance to the point that GS inhibition might be considered a conceivable strategy against cancer metastasis.
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22
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Marcet P, Santos N, Borlongan CV. When friend turns foe: central and peripheral neuroinflammation in central nervous system injury. ACTA ACUST UNITED AC 2017; 4:82-92. [PMID: 29670933 PMCID: PMC5901724 DOI: 10.20517/2347-8659.2017.07] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Injury to the central nervous system (CNS) is common, and though it has been well studied, many aspects of traumatic brain injury (TBI) and stroke are poorly understood. TBI and stroke are two pathologic events that can cause severe, immediate impact to the neurostructure and function of the CNS, which has been recognized recently to be exacerbated by the body’s own immune response. Although the brain damage induced by the initial trauma is most likely unsalvageable, the secondary immunologic deterioration of neural tissue gives ample opportunity for therapeutic strategists seeking to mitigate TBI’s secondary detrimental effects. The purpose of this paper is to highlight the cell death mechanisms associated with CNS injury with special emphasis on inflammation. The authors discuss sources of inflammation, and introduce the role of the spleen in the systemic response to inflammation after CNS injury.
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Affiliation(s)
- Paul Marcet
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA
| | - Nicole Santos
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA
| | - Cesar V Borlongan
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA
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23
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Palmieri EM, Menga A, Lebrun A, Hooper DC, Butterfield DA, Mazzone M, Castegna A. Blockade of Glutamine Synthetase Enhances Inflammatory Response in Microglial Cells. Antioxid Redox Signal 2017; 26:351-363. [PMID: 27758118 PMCID: PMC5346956 DOI: 10.1089/ars.2016.6715] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIMS Microglial cells are brain-resident macrophages engaged in surveillance and maintained in a constant state of relative inactivity. However, their involvement in autoimmune diseases indicates that in pathological conditions microglia gain an inflammatory phenotype. The mechanisms underlying this change in the microglial phenotype are still unclear. Since metabolism is an important modulator of immune cell function, we focused our attention on glutamine synthetase (GS), a modulator of the response to lipopolysaccharide (LPS) activation in other cell types, which is expressed by microglia. RESULTS GS inhibition enhances release of inflammatory mediators of LPS-activated microglia in vitro, leading to perturbation of the redox balance and decreased viability of cocultured neurons. GS inhibition also decreases insulin-mediated glucose uptake in microglia. In vivo, microglia-specific GS ablation enhances expression of inflammatory markers upon LPS treatment. In the spinal cords from experimental autoimmune encephalomyelitis (EAE), GS expression levels and glutamine/glutamate ratios are reduced. INNOVATION Recently, metabolism has been highlighted as mediator of immune cell function through the discovery of mechanisms that (behind these metabolic changes) modulate the inflammatory response. The present study shows for the first time a metabolic mechanism mediating microglial response to a proinflammatory stimulus, pointing to GS activity as a master modulator of immune cell function and thus unraveling a potential therapeutic target. CONCLUSIONS Our study highlights a new role of GS in modulating immune response in microglia, providing insights into the pathogenic mechanisms associated with inflammation and new strategies of therapeutic intervention. Antioxid. Redox Signal. 26, 351-363.
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Affiliation(s)
- Erika M Palmieri
- 1 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari , Bari, Italy
| | - Alessio Menga
- 2 National Cancer Research Center, Istituto Tumori 'Giovanni Paolo II,' Bari, Italy
| | - Aurore Lebrun
- 3 Department of Cancer Biology, Thomas Jefferson University , Philadelphia, Pennsylvania.,4 Department of Neurological Surgery, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - Douglas C Hooper
- 3 Department of Cancer Biology, Thomas Jefferson University , Philadelphia, Pennsylvania.,4 Department of Neurological Surgery, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - D Allan Butterfield
- 5 Department of Chemistry, University of Kentucky , Lexington, Kentucky.,6 Sanders-Brown Center on Aging, University of Kentucky , Lexington, Kentucky
| | - Massimiliano Mazzone
- 7 Laboratory of Tumor Inflammation and Angiogenesis, Department of Oncology, University of Leuven , Leuven, Belgium .,8 Laboratory of Tumor Inflammation and Angiogenesis, Vesalius Research Center, VIB, Leuven, Belgium
| | - Alessandra Castegna
- 1 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari , Bari, Italy .,2 National Cancer Research Center, Istituto Tumori 'Giovanni Paolo II,' Bari, Italy
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24
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Miller AP, Shah AS, Aperi BV, Kurpad SN, Stemper BD, Glavaski-Joksimovic A. Acute death of astrocytes in blast-exposed rat organotypic hippocampal slice cultures. PLoS One 2017; 12:e0173167. [PMID: 28264063 PMCID: PMC5338800 DOI: 10.1371/journal.pone.0173167] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 02/16/2017] [Indexed: 01/06/2023] Open
Abstract
Blast traumatic brain injury (bTBI) affects civilians, soldiers, and veterans worldwide and presents significant health concerns. The mechanisms of neurodegeneration following bTBI remain elusive and current therapies are largely ineffective. It is important to better characterize blast-evoked cellular changes and underlying mechanisms in order to develop more effective therapies. In the present study, our group utilized rat organotypic hippocampal slice cultures (OHCs) as an in vitro system to model bTBI. OHCs were exposed to either 138 ± 22 kPa (low) or 273 ± 23 kPa (high) overpressures using an open-ended helium-driven shock tube, or were assigned to sham control group. At 2 hours (h) following injury, we have characterized the astrocytic response to a blast overpressure. Immunostaining against the astrocytic marker glial fibrillary acidic protein (GFAP) revealed acute shearing and morphological changes in astrocytes, including clasmatodendrosis. Moreover, overlap of GFAP immunostaining and propidium iodide (PI) indicated astrocytic death. Quantification of the number of dead astrocytes per counting area in the hippocampal cornu Ammonis 1 region (CA1), demonstrated a significant increase in dead astrocytes in the low- and high-blast, compared to sham control OHCs. However only a small number of GFAP-expressing astrocytes were co-labeled with the apoptotic marker Annexin V, suggesting necrosis as the primary type of cell death in the acute phase following blast exposure. Moreover, western blot analyses revealed calpain mediated breakdown of GFAP. The dextran exclusion additionally indicated membrane disruption as a potential mechanism of acute astrocytic death. Furthermore, although blast exposure did not evoke significant changes in glutamate transporter 1 (GLT-1) expression, loss of GLT-1-expressing astrocytes suggests dysregulation of glutamate uptake following injury. Our data illustrate the profound effect of blast overpressure on astrocytes in OHCs at 2 h following injury and suggest increased calpain activity and membrane disruption as potential underlying mechanisms.
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Affiliation(s)
- Anna P. Miller
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
| | - Alok S. Shah
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
| | - Brandy V. Aperi
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
| | - Shekar N. Kurpad
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
| | - Brian D. Stemper
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
| | - Aleksandra Glavaski-Joksimovic
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, United States of America
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25
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Microglia derived from the axotomized adult rat facial nucleus uptake glutamate and metabolize it to glutamine in vitro. Neurochem Int 2016; 102:1-12. [PMID: 27816478 DOI: 10.1016/j.neuint.2016.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 09/12/2016] [Accepted: 10/31/2016] [Indexed: 11/22/2022]
Abstract
Microglia in the axotomized adult rat facial nucleus (axoFN) have been shown to highly express a glutamate transporter (GLT-1). The microglia appear to serve as glutamate (Glu) scavengers in the axoFN. However, there is no evidence that the microglia actually have the ability to uptake Glu and convert it to Gln. In this study, we investigated whether axoFN-derived microglia (axoFN-microglia) can uptake Glu and metabolize it to Gln. Microglia obtained by explant culture of axoFN on poly(N-isopropylacrylamide)-grafted dishes were non-invasively sub-cultured onto dishes or wells. Immunoblotting and Glu-uptake experiments revealed that the axoFN-microglia uptake 14C-Glu mainly by GLT-1 activity. Immunoblotting and immunocytochemical methods clarified that axoFN-microglia express the Gln synthetase (GS) protein in the same manner as newborn rat brain-derived primary microglia (NRB-microglia). Biochemical analysis demonstrated that the specific activity of GS of axoFN-microglia is similar to that of NRB-microglia, suggesting that these microglia play equivalent roles in the metabolic conversion of Glu to Gln. Nuclear magnetic resonance analysis clarified that NRB-microglia metabolize [13C]Glu to [13C]Gln depending on the incubation time, inferring the similar potential of axoFN-microglia. Taken together, these results demonstrate that axoFN-microglia express functional GLT-1 and GS proteins, and are strongly suggested to serve as Glu scavengers in vivo.
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Dorsett CR, McGuire JL, Niedzielko TL, DePasquale EAK, Meller J, Floyd CL, McCullumsmith RE. Traumatic Brain Injury Induces Alterations in Cortical Glutamate Uptake without a Reduction in Glutamate Transporter-1 Protein Expression. J Neurotrauma 2016; 34:220-234. [PMID: 27312729 DOI: 10.1089/neu.2015.4372] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We hypothesize that the primary mechanism for removal of glutamate from the extracellular space is altered after traumatic brain injury (TBI). To evaluate this hypothesis, we initiated TBI in adult male rats using a 2.0 atm lateral fluid percussion injury (LFPI) model. In the ipsilateral cortex and hippocampus, we found no differences in expression of the primary glutamate transporter in the brain (GLT-1) 24 h after TBI. In contrast, we found a decrease in glutamate uptake in the cortex, but not the hippocampus, 24 h after injury. Because glutamate uptake is potently regulated by protein kinases, we assessed global serine-threonine protein kinase activity using a kinome array platform. Twenty-five kinome array peptide substrates were differentially phoshorylated between LFPI and controls in the cortex, whereas 19 peptide substrates were differentially phosphorylated in the hippocampus (fold change ≥ ± 1.15). We identified several kinases as likely to be involved in acute TBI, including protein kinase B (Akt) and protein kinase C (PKC), which are well-characterized modulators of GLT-1. Exploratory studies using an inhibitor of Akt suggest selective activation of kinases in LFPI versus controls. Ingenuity pathway analyses of implicated kinases from our network model found apoptosis and cell death pathways as top functions in acute LFPI. Taken together, our data suggest diminished activity of glutamate transporters in the prefrontal cortex, with no changes in protein expression of the primary glutamate transporter GLT-1, and global alterations in signaling networks that include serine-threonine kinases that are known modulators of glutamate transport activity.
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Affiliation(s)
- Christopher R Dorsett
- 1 Biological and Biomedical Sciences Doctoral Program, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Jennifer L McGuire
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
| | - Tracy L Niedzielko
- 3 Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham , Birmingham, Alabama
| | - Erica A K DePasquale
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
| | - Jaroslaw Meller
- 4 Departments of Environmental Health, Electrical Engineering & Computing Systems, and Biomedical Informatics, University of Cincinnati College of Medicine , Cincinnati, Ohio.,5 Department of Biomedical Informatics, Cincinnati Children's Hospital Medical Center , Cincinnati, Ohio
| | - Candace L Floyd
- 3 Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham , Birmingham, Alabama
| | - Robert E McCullumsmith
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
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Dorsett CR, McGuire JL, DePasquale EAK, Gardner AE, Floyd CL, McCullumsmith RE. Glutamate Neurotransmission in Rodent Models of Traumatic Brain Injury. J Neurotrauma 2016; 34:263-272. [PMID: 27256113 DOI: 10.1089/neu.2015.4373] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Traumatic brain injury (TBI) is a leading cause of death and disability in people younger than 45 and is a significant public health concern. In addition to primary mechanical damage to cells and tissue, TBI involves additional molecular mechanisms of injury, termed secondary injury, that continue to evolve over hours, days, weeks, and beyond. The trajectory of recovery after TBI is highly unpredictable and in many cases results in chronic cognitive and behavioral changes. Acutely after TBI, there is an unregulated release of glutamate that cannot be buffered or cleared effectively, resulting in damaging levels of glutamate in the extracellular space. This initial loss of glutamate homeostasis may initiate additional changes in glutamate regulation. The excitatory amino acid transporters (EAATs) are expressed on both neurons and glia and are the principal mechanism for maintaining extracellular glutamate levels. Diffusion of glutamate outside the synapse due to impaired uptake may lead to increased extrasynaptic glutamate signaling, secondary injury through activation of cell death pathways, and loss of fidelity and specificity of synaptic transmission. Coordination of glutamate release and uptake is critical to regulating synaptic strength, long-term potentiation and depression, and cognitive processes. In this review, we will discuss dysregulation of extracellular glutamate and glutamate uptake in the acute stage of TBI and how failure to resolve acute disruptions in glutamate homeostatic mechanisms may play a causal role in chronic cognitive symptoms after TBI.
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Affiliation(s)
- Christopher R Dorsett
- 1 Biological and Biomedical Sciences Doctoral Program, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Jennifer L McGuire
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
| | - Erica A K DePasquale
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
| | - Amanda E Gardner
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
| | - Candace L Floyd
- 3 Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham , Birmingham, Alabama
| | - Robert E McCullumsmith
- 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio
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Cytokine and Growth Factor Activation In Vivo and In Vitro after Spinal Cord Injury. Mediators Inflamm 2016; 2016:9476020. [PMID: 27418745 PMCID: PMC4935915 DOI: 10.1155/2016/9476020] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/18/2016] [Indexed: 12/22/2022] Open
Abstract
Spinal cord injury results in a life-disrupting series of deleterious interconnected mechanisms encompassed by the primary and secondary injury. These events are mediated by the upregulation of genes with roles in inflammation, transcription, and signaling proteins. In particular, cytokines and growth factors are signaling proteins that have important roles in the pathophysiology of SCI. The balance between the proinflammatory and anti-inflammatory effects of these molecules plays a critical role in the progression and outcome of the lesion. The excessive inflammatory Th1 and Th17 phenotypes observed after SCI tilt the scale towards a proinflammatory environment, which exacerbates the deleterious mechanisms present after the injury. These mechanisms include the disruption of the spinal cord blood barrier, edema and ion imbalance, in particular intracellular calcium and sodium concentrations, glutamate excitotoxicity, free radicals, and the inflammatory response contributing to the neurodegenerative process which is characterized by demyelination and apoptosis of neuronal tissue.
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Decreased cysteine uptake by EAAC1 gene deletion exacerbates neuronal oxidative stress and neuronal death after traumatic brain injury. Amino Acids 2016; 48:1619-29. [DOI: 10.1007/s00726-016-2221-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 03/21/2016] [Indexed: 12/22/2022]
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Holt LM, Olsen ML. Novel Applications of Magnetic Cell Sorting to Analyze Cell-Type Specific Gene and Protein Expression in the Central Nervous System. PLoS One 2016; 11:e0150290. [PMID: 26919701 PMCID: PMC4769085 DOI: 10.1371/journal.pone.0150290] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 02/11/2016] [Indexed: 12/21/2022] Open
Abstract
The isolation and study of cell-specific populations in the central nervous system (CNS) has gained significant interest in the neuroscience community. The ability to examine cell-specific gene and protein expression patterns in healthy and pathological tissue is critical for our understanding of CNS function. Several techniques currently exist to isolate cell-specific populations, each having their own inherent advantages and shortcomings. Isolation of distinct cell populations using magnetic sorting is a technique which has been available for nearly 3 decades, although rarely used in adult whole CNS tissue homogenate. In the current study we demonstrate that distinct cell populations can be isolated in rodents from early postnatal development through adulthood. We found this technique to be amendable to customization using commercially available membrane-targeted antibodies, allowing for cell-specific isolation across development and animal species. This technique yields RNA which can be utilized for downstream applications—including quantitative PCR and RNA sequencing—at relatively low cost and without the need for specialized equipment or fluorescently labeled cells. Adding to its utility, we demonstrate that cells can be isolated largely intact, retaining their processes, enabling analysis of extrasomatic proteins. We propose that magnetic cell sorting will prove to be a highly useful technique for the examination of cell specific CNS populations.
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Affiliation(s)
- Leanne Melissa Holt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Michelle Lynne Olsen
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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31
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Huang C, Yuan P, Wu J, Huang J. Estrogen regulates excitatory amino acid carrier 1 (EAAC1) expression through sphingosine kinase 1 (SphK1) transacting FGFR-mediated ERK signaling in rat C6 astroglial cells. Neuroscience 2016; 319:9-22. [PMID: 26804240 DOI: 10.1016/j.neuroscience.2016.01.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/04/2016] [Accepted: 01/12/2016] [Indexed: 12/28/2022]
Abstract
Excitatory amino acid carrier 1 (EAAC1) is one important subtype of the excitatory amino acid transporters (EAATs), and its absence can increase the vulnerability to oxidative stress in neural tissue. Enhanced expression of EAAC1 can provide neuroprotection in multiple disorders, including ischemia and multiple sclerosis. However, the mechanism regulating EAAC1 expression is not fully understood. Using rat C6 astroglial cells, which specifically express EAAC1, we found that 17β-estradiol (E2) and (±)-1-[(3aR(∗),4S(∗),9bS(∗))-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone (G1), an agonist of the G-protein-coupled estrogen receptor (GPR30), strongly increased EAAC1 protein levels and protected cells from hydrogen peroxide (H2O2) toxicity. We further found that E2/G1 activated sphingosine kinase 1 (SphK1) via GPR30, resulting in the transcription of fibroblast growth factor 2 (FGF2), which stimulated its receptor (FGFR) and led to the phosphorylation of FGFR substrate 2α (FRS2α). This triggered downstream ERK1/2 signaling for the expression of EAAC1. Both the knockdown of FGF2 by siRNA and the pharmacological suppression of the FGFR-ERK cascade abolished the E2/G1 effect on EAAC1 expression. Overall, our work characterizes a signaling pathway by which E2 transactivates FGFR-ERK to induce EAAC1 expression in an FGF2-dependent manner. This occurs through SphK1 activation via GPR30 and leads to a resistance to H2O2 toxicity. This signal transduction pathway may provide novel insights into our understanding of the neuroprotective effects of E2 and may reveal new therapeutic targets or drugs for regulating the oxidative toxicity effects of various neurological diseases.
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Affiliation(s)
- C Huang
- College of Life Science, Wuhan University, Wuhan 430072, PR China
| | - P Yuan
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, USA
| | - J Wu
- College of Life Science, Wuhan University, Wuhan 430072, PR China
| | - J Huang
- College of Life Science, Wuhan University, Wuhan 430072, PR China.
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Rohrbeck A, Stahl F, Höltje M, Hettwer T, Lindner P, Hagemann S, Pich A, Haastert-Talini K. C3-induced release of neurotrophic factors from Schwann cells - potential mechanism behind its regeneration promoting activity. Neurochem Int 2015; 90:232-45. [PMID: 26417907 DOI: 10.1016/j.neuint.2015.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/11/2015] [Accepted: 09/23/2015] [Indexed: 01/10/2023]
Abstract
Previous studies revealed a peripheral nerve regeneration (PNR)(1) promoting activity of Clostridium botulinum C3(2) exoenzyme or a 26(mer) C-terminal peptide fragment covering amino acids 156-181 (C3(156-181)),(3) when delivered as one-time injection at the lesion site. The current study was performed to 1) investigate if prolonged availability of C3 and C3(156-181) at the lesion site can further enhance PNR in vivo and to 2) elucidate effects of C3 and C3(156-181) on Schwann cells (SCs)(4)in vitro. For in vivo studies, 10 mm adult rat sciatic nerve gaps were reconstructed with the epineurial pouch technique or autologous nerve grafts. Epineurial pouches were filled with a hydrogel containing i) vehicle, ii) 40 μM C3 or iii) 40 μM C3(156-181). Sensory and motor functional recovery was monitored over 12 weeks and the outcome of PNR further analyzed by nerve morphometry. In vitro, we compared gene expression profiles (microarray analysis) and neurotrophic factor expression (western blot analysis) of untreated rat neonatal SCs with those treated with C3 or C3(156-181) for 72 h. Effects on neurotrophic factor expression levels were proven in adult human SCs. Unexpectedly, prolonged delivery of C3 and C3(156-181) at the lesion site did not increase the outcome of PNR. Regarding the potential mechanism underlying their previously detected PNR promoting action, however, 6 genes were found to be commonly altered in SCs upon treatment with C3 or C3(156-181). We demonstrate significant down-regulation of genes involved in glutamate uptake (Eaac1,(5)Grin2a(6)) and changes in neurotrophic factor expression (increase of FGF-2(7) and decrease of NGF(8)). Our microarray-based expression profiling revealed novel C3-regulated genes in SCs possibly involved in the axonotrophic (regeneration promoting) effects of C3 and C3(156-181). Detection of altered neurotrophic factor expression by C3 or C3(156-181) treated primary neonatal rat SCs and primary adult human SCs supports this hypothesis.
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Affiliation(s)
- Astrid Rohrbeck
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
| | - Frank Stahl
- Institute for Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, D-30167 Hannover, Germany
| | - Markus Höltje
- Institute for Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany
| | - Timo Hettwer
- Institute of Neuroanatomy, Hannover Medical School and Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Patrick Lindner
- Institute for Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, D-30167 Hannover, Germany
| | - Sandra Hagemann
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Andreas Pich
- Institute of Toxicology, Hannover Medical School, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany
| | - Kirsten Haastert-Talini
- Institute of Neuroanatomy, Hannover Medical School and Carl-Neuberg-Str. 1, D-30625 Hannover, Germany; Center for Systems Neuroscience (ZSN), Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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33
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Feng D, Guo B, Liu G, Wang B, Wang W, Gao G, Qin H, Wu S. FGF2 alleviates PTSD symptoms in rats by restoring GLAST function in astrocytes via the JAK/STAT pathway. Eur Neuropsychopharmacol 2015; 25:1287-99. [PMID: 25979764 DOI: 10.1016/j.euroneuro.2015.04.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 04/06/2015] [Accepted: 04/24/2015] [Indexed: 12/18/2022]
Abstract
In our previous study, we demonstrated that fibroblast growth factor 2 (FGF2) administration alleviated posttraumatic stress disorder (PTSD) symptoms via an "astrocyte-related" mechanism. We further investigated the changes in the astrocytic glutamate transporters GLAST and GLT-1 and in JAK/STAT3 signaling (which is involved in astrocyte activation and GLAST/GLT-1 function) in single prolonged stress (SPS) model rats. High-performance liquid chromatography (HPLC), Western blot and immunohistochemistry analyses revealed a significant SPS-induced increase in the concentration of glutamate in the cerebrospinal fluid and decrease in GLAST/GLT-1 expression and JAK/STAT3 signaling. Treatment with FGF2 significantly alleviated GLAST/GLT-1 dysfunction, JAK/STAT3 signaling inhibition, and the behavioral abnormalities. The administration of the JAK/STAT pathway inhibitor AG490 blocked the effects of FGF2 on PTSD symptoms, astrocyte activation, and GLAST, but not GLT-1, expression in vivo and in vitro. Our findings suggest that astrocytic JAK/STAT signaling is associated with SPS-induced GLAST dysfunction and that FGF2 protects against PTSD symptoms by restoring astrocytic glutamate uptake via the JAK/STAT signaling pathway.
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Affiliation(s)
- Dayun Feng
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, PR China; Department of Neurosurgery and Institute for Functional Brain Disorders, Tangdu Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Baolin Guo
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, PR China
| | - Gaohua Liu
- Department of Psychosomatics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Bao Wang
- Department of Neurosurgery and Institute for Functional Brain Disorders, Tangdu Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Wen Wang
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, PR China
| | - Guodong Gao
- Department of Neurosurgery and Institute for Functional Brain Disorders, Tangdu Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Huaizhou Qin
- Department of Neurosurgery and Institute for Functional Brain Disorders, Tangdu Hospital, Fourth Military Medical University, Xi'an 710032, PR China.
| | - Shengxi Wu
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an 710032, PR China.
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Astroglia-Microglia Cross Talk during Neurodegeneration in the Rat Hippocampus. BIOMED RESEARCH INTERNATIONAL 2015; 2015:102419. [PMID: 25977914 PMCID: PMC4419226 DOI: 10.1155/2015/102419] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/16/2015] [Accepted: 03/09/2015] [Indexed: 01/30/2023]
Abstract
Brain injury triggers a progressive inflammatory response supported by a dynamic astroglia-microglia interplay. We investigated the progressive chronic features of the astroglia-microglia cross talk in the perspective of neuronal effects in a rat model of hippocampal excitotoxic injury. N-Methyl-D-aspartate (NMDA) injection triggered a process characterized within 38 days by atrophy, neuronal loss, and fast astroglia-mediated S100B increase. Microglia reaction varied with the lesion progression. It presented a peak of tumor necrosis factor-α (TNF-α) secretion at one day after the lesion, and a transient YM1 secretion within the first three days. Microglial glucocorticoid receptor expression increased up to day 5, before returning progressively to sham values. To further investigate the astroglia role in the microglia reaction, we performed concomitant transient astroglia ablation with L-α-aminoadipate and NMDA-induced lesion. We observed a striking maintenance of neuronal death associated with enhanced microglial reaction and proliferation, increased YM1 concentration, and decreased TNF-α secretion and glucocorticoid receptor expression. S100B reactivity only increased after astroglia recovery. Our results argue for an initial neuroprotective microglial reaction, with a direct astroglial control of the microglial cytotoxic response. We propose the recovery of the astroglia-microglia cross talk as a tissue priority conducted to ensure a proper cellular coordination that retails brain damage.
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Nakajima K, Kanamatsu T, Takezawa Y, Kohsaka S. Up-regulation of glutamine synthesis in microglia activated with endotoxin. Neurosci Lett 2015; 591:99-104. [DOI: 10.1016/j.neulet.2015.02.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 01/31/2015] [Accepted: 02/10/2015] [Indexed: 11/24/2022]
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Mortazavi MM, Verma K, Harmon OA, Griessenauer CJ, Adeeb N, Theodore N, Tubbs RS. The microanatomy of spinal cord injury: A review. Clin Anat 2014; 28:27-36. [DOI: 10.1002/ca.22432] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 06/23/2014] [Indexed: 01/08/2023]
Affiliation(s)
| | - Ketan Verma
- Pediatric Neurosurgery; Children's of Alabama
| | | | | | - Nimer Adeeb
- Pediatric Neurosurgery; Children's of Alabama
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37
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Morley WA, Seneff S. Diminished brain resilience syndrome: A modern day neurological pathology of increased susceptibility to mild brain trauma, concussion, and downstream neurodegeneration. Surg Neurol Int 2014; 5:97. [PMID: 25024897 PMCID: PMC4093745 DOI: 10.4103/2152-7806.134731] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 03/31/2014] [Indexed: 12/11/2022] Open
Abstract
The number of sports-related concussions has been steadily rising in recent years. Diminished brain resilience syndrome is a term coined by the lead author to describe a particular physiological state of nutrient functional deficiency and disrupted homeostatic mechanisms leading to increased susceptibility to previously considered innocuous concussion. We discuss how modern day environmental toxicant exposure, along with major changes in our food supply and lifestyle practices, profoundly reduce the bioavailability of neuro-critical nutrients such that the normal processes of homeostatic balance and resilience are no longer functional. Their diminished capacity triggers physiological and biochemical 'work around' processes that result in undesirable downstream consequences. Exposure to certain environmental chemicals, particularly glyphosate, the active ingredient in the herbicide, Roundup(®), may disrupt the body's innate switching mechanism, which normally turns off the immune response to brain injury once danger has been removed. Deficiencies in serotonin, due to disruption of the shikimate pathway, may lead to impaired melatonin supply, which reduces the resiliency of the brain through reduced antioxidant capacity and alterations in the cerebrospinal fluid, reducing critical protective buffering mechanisms in impact trauma. Depletion of certain rare minerals, overuse of sunscreen and/or overprotection from sun exposure, as well as overindulgence in heavily processed, nutrient deficient foods, further compromise the brain's resilience. Modifications to lifestyle practices, if widely implemented, could significantly reduce this trend of neurological damage.
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Affiliation(s)
| | - Stephanie Seneff
- Spoken Language Systems Group, Computer Science and Artificial Intelligence Laboratory, MIT, Cambridge MA 02139, USA
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Bianchi MG, Bardelli D, Chiu M, Bussolati O. Changes in the expression of the glutamate transporter EAAT3/EAAC1 in health and disease. Cell Mol Life Sci 2014; 71:2001-15. [PMID: 24162932 PMCID: PMC11113519 DOI: 10.1007/s00018-013-1484-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/17/2013] [Accepted: 09/19/2013] [Indexed: 12/14/2022]
Abstract
Excitatory amino acid transporters (EAATs) are high-affinity Na(+)-dependent carriers of major importance in maintaining glutamate homeostasis in the central nervous system. EAAT3, the human counterpart of the rodent excitatory amino acid carrier 1 (EAAC1), is encoded by the SLC1A1 gene. EAAT3/EAAC1 is ubiquitously expressed in the brain, mostly in neurons but also in other cell types, such as oligodendrocyte precursors. While most of the glutamate released in the synapses is taken up by the "glial-type" EAATs, EAAT2 (GLT-1 in rodents) and EAAT1 (GLAST), the functional role of EAAT3/EAAC1 is related to the subtle regulation of glutamatergic transmission. Moreover, because it can also transport cysteine, EAAT3/EAAC1 is believed to be important for the synthesis of intracellular glutathione and subsequent protection from oxidative stress. In contrast to other EAATs, EAAT3/EAAC1 is mostly intracellular, and several mechanisms have been described for the rapid regulation of the membrane trafficking of the transporter. Moreover, the carrier interacts with several proteins, and this interaction modulates transport activity. Much less is known about the slow regulatory mechanisms acting on the expression of the transporter, although several recent reports have identified changes in EAAT3/EAAC1 protein level and activity related to modulation of its expression at the gene level. Moreover, EAAT3/EAAC1 expression is altered in pathological conditions, such as hypoxia/ischemia, multiple sclerosis, schizophrenia, and epilepsy. This review summarizes these results and provides an overall picture of changes in EAAT3/EAAC1 expression in health and disease.
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Affiliation(s)
- Massimiliano G. Bianchi
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
- Unit of Occupational Medicine, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy
| | - Donatella Bardelli
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
| | - Martina Chiu
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
| | - Ovidio Bussolati
- Unit of General Pathology, Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT), University of Parma, Via Volturno 39, 43125 Parma, Italy
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39
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Thompson CD, Zurko JC, Hanna BF, Hellenbrand DJ, Hanna A. The therapeutic role of interleukin-10 after spinal cord injury. J Neurotrauma 2013; 30:1311-24. [PMID: 23731227 DOI: 10.1089/neu.2012.2651] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Spinal cord injury (SCI) is a devastating condition affecting 270,000 people in the United States. A potential treatment for decreasing the secondary inflammation, excitotoxic damage, and neuronal apoptosis associated with SCI, is the anti-inflammatory cytokine interleukin-10. The best characterized effects of IL-10 are anti-inflammatory-it downregulates pro-inflammatory species interleukin-1β (IL-1β), interleukin-2 (IL-2), interleukin-6 (IL-6), tumor necrosis factor-α, interferon-γ, matrix metalloproteinase-9, nitric oxide synthase, myeloperoxidase, and reactive oxygen species. Pro-apoptotic factors cytochrome c, caspase 3, and Bax are downregulated by IL-10, whereas anti-apoptotic factors B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X, B-cell lymphoma-extra large (Bcl-xl) are upregulated by IL-10. IL-10 also provides trophic support to neurons through the IL-10 receptor. Increased tissue sparing, functional recovery, and neuroprotection are seen with an immediate post-SCI systemic administration of IL-10. Treatment of SCI with IL-10 has been used successfully in combination with Schwann cell and olfactory glial cell grafts, as well as methylprednisolone. Minocycline, tetramethylpyrazine, and hyperbaric oxygen treatment all increase IL-10 levels in a SCI models and result in increased tissue sparing and functional recovery. A chronic systemic administration of IL-10 does not appear to be beneficial to SCI recovery and causes increased susceptibility to septicemia, pneumonia, and peripheral neuropathy. However, a localized upregulation of IL-10 has been shown to be beneficial and can be achieved by herpes simplex virus gene therapy, injection of poliovirus replicons, or surgical placement of a slow-release compound. IL-10 shows promise as a treatment for SCI, although research on local IL-10 delivery timeline and dosage needs to be expanded.
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Affiliation(s)
- Colton D Thompson
- Department of Neurological Surgery, University of Wisconsin , Madison, Wisconsin, USA
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40
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Kettenmann H, Kirchhoff F, Verkhratsky A. Microglia: new roles for the synaptic stripper. Neuron 2013; 77:10-8. [PMID: 23312512 DOI: 10.1016/j.neuron.2012.12.023] [Citation(s) in RCA: 844] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2012] [Indexed: 01/23/2023]
Abstract
Any pathologic event in the brain leads to the activation of microglia, the immunocompetent cells of the central nervous system. In recent decades diverse molecular pathways have been identified by which microglial activation is controlled and by which the activated microglia affects neurons. In the normal brain microglia were considered "resting," but it has recently become evident that they constantly scan the brain environment and contact synapses. Activated microglia can remove damaged cells as well as dysfunctional synapses, a process termed "synaptic stripping." Here we summarize evidence that molecular pathways characterized in pathology are also utilized by microglia in the normal and developing brain to influence synaptic development and connectivity, and therefore should become targets of future research. Microglial dysfunction results in behavioral deficits, indicating that microglia are essential for proper brain function. This defines a new role for microglia beyond being a mere pathologic sensor.
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Wei J, Pan X, Pei Z, Wang W, Qiu W, Shi Z, Xiao G. The beta-lactam antibiotic, ceftriaxone, provides neuroprotective potential via anti-excitotoxicity and anti-inflammation response in a rat model of traumatic brain injury. J Trauma Acute Care Surg 2012; 73:654-60. [PMID: 22710775 DOI: 10.1097/ta.0b013e31825133c0] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The beta-lactam antibiotic, ceftriaxone (CTX), has been reported to induce neuroprotection in animal models of diverse neurologic diseases. Currently, no data have explored the potential for CTX to provide neuroprotection in the animal models of traumatic brain injury (TBI). The aim of this study was to investigate the neuroprotective effect by CTX on TBI and to determine the underlying mechanisms. METHODS Rats were immediately subjected to a lateral cortical impact injury caused by a free-falling object and divided randomly into three groups: sham-operated, trauma, and trauma + CTX treatment group. The CTX treatment group was given CTX (200 mg/kg of body weight, intravenously) immediately after injury. The cognitive function was assessed by Y-maze testing and cerebral edema was evaluated. Inflammatory cytokines expression was measured using enzyme-linked immunosorbent assay array. The expression of glutamate transporter-1 protein was identified by Western blot analysis. RESULTS This study shows that the CTX causes attenuation of TBI-induced cerebral edema and cognitive function deficits. CTX treatment significantly reduced levels of the proinflammatory cytokines interleukin-1[beta], interferon-[gamma], and tumor necrosis factor-[alpha] and up-regulated glutamate transporter-1 expression after TBI. CONCLUSION Our results provide in vivo evidence that CTX could exert neuroprotective effect against TBI by improving cognitive function and alleviating brain edema via reducing excitotoxicity and inflammation after TBI.
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Affiliation(s)
- Jing Wei
- Medical Center, the Affiliated Hospital of Hangzhou Normal University, Hangzhou, China
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Streit WJ, Xue QS. Alzheimer's disease, neuroprotection, and CNS immunosenescence. Front Pharmacol 2012; 3:138. [PMID: 22822399 PMCID: PMC3398410 DOI: 10.3389/fphar.2012.00138] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 06/25/2012] [Indexed: 01/07/2023] Open
Abstract
This review is focused on discussing in some detail possible neuroprotective functions of microglial cells. We strive to explain how loss of these essential microglial functions might contribute toward the development of characteristic neuropathological features that characterize Alzheimer’s disease. The conceptual framework guiding our thinking is provided by the hypothesis that microglial senescence accounts for impaired neuronal protection and consequent neurodegeneration.
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Affiliation(s)
- Wolfgang J Streit
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute Gainesville, FL, USA
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Hinzman JM, Thomas TC, Quintero JE, Gerhardt GA, Lifshitz J. Disruptions in the regulation of extracellular glutamate by neurons and glia in the rat striatum two days after diffuse brain injury. J Neurotrauma 2012; 29:1197-208. [PMID: 22233432 DOI: 10.1089/neu.2011.2261] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Disrupted regulation of extracellular glutamate in the central nervous system contributes to and can exacerbate the acute pathophysiology of traumatic brain injury (TBI). Previously, we reported increased extracellular glutamate in the striatum of anesthetized rats 2 days after diffuse brain injury. To determine the mechanism(s) responsible for increased extracellular glutamate, we used enzyme-based microelectrode arrays (MEAs) coupled with specific pharmacological agents targeted at in vivo neuronal and glial regulation of extracellular glutamate. After TBI, extracellular glutamate was significantly increased in the striatum by (∼90%) averaging 4.1±0.6 μM compared with sham 2.2±0.4 μM. Calcium-dependent neuronal glutamate release, investigated by local application of an N-type calcium channel blocker, was no longer a significant source of extracellular glutamate after TBI, compared with sham. In brain-injured animals, inhibition of glutamate uptake with local application of an excitatory amino acid transporter inhibitor produced significantly greater increase in glutamate spillover (∼ 65%) from the synapses compared with sham. Furthermore, glutamate clearance measured by locally applying glutamate into the extracellular space revealed significant reductions in glutamate clearance parameters in brain-injured animals compared with sham. Taken together, these data indicate that disruptions in calcium-mediated glutamate release and glial regulation of extracellular glutamate contribute to increased extracellular glutamate in the striatum 2 days after diffuse brain injury. Overall, these data suggest that therapeutic strategies used to regulate glutamate release and uptake may improve excitatory circuit function and, possibly, outcomes following TBI.
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Affiliation(s)
- Jason M Hinzman
- Department of Anatomy and Neurobiology, University of Kentucky Chandler Medical Center, Lexington, Kentucky 40536-0509, USA
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Jungblut M, Tiveron MC, Barral S, Abrahamsen B, Knöbel S, Pennartz S, Schmitz J, Perraut M, Pfrieger FW, Stoffel W, Cremer H, Bosio A. Isolation and characterization of living primary astroglial cells using the new GLAST-specific monoclonal antibody ACSA-1. Glia 2012; 60:894-907. [PMID: 22374709 DOI: 10.1002/glia.22322] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 02/14/2012] [Indexed: 12/23/2022]
Abstract
Astrocytes show large morphological and functional heterogeneity and are involved in many aspects of neural function. Progress in defining astrocyte subpopulations has been hampered by the lack of a suitable antibody for their direct detection and isolation. Here, we describe a new monoclonal antibody, ACSA-1, which was generated by immunization of GLAST1 knockout mice. The antibody specifically detects an extracellular epitope of the astrocyte-specific L-glutamate/L-aspartate transporter GLAST (EAAT1, Slc1a3). As shown by immunohistochemistry, immunocytochemistry, and flow cytometry, ACSA-1 was cross-reactive for mouse, human, and rat. It labeled virtually all astrocytes positive for GFAP, GS, BLBP, RC2, and Nestin, including protoplastic, fibrous, and reactive astrocytes as well as Bergmann glia, Müller glia, and radial glia. Oligodendrocytes, microglia, neurons, and neuronal progenitors were negative for ACSA-1. Using an immunomagnetic approach, we established a method for the isolation of GLAST-positive cells with high purity. Binding of the antibody to GLAST and subsequent sorting of GLAST-positive cells neither interfered with cellular glutamate transport nor compromised astrocyte viability in vitro. The ACSA-1 antibody is not only a valuable tool to identify and track astrocytes by immunostaining, but also provides the possibility of separation and further analysis of pure astrocytes.
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Affiliation(s)
- Melanie Jungblut
- Miltenyi Biotec GmbH, Friedrich-Ebert-Straße 68, Bergisch Gladbach, Germany
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Thomas TC, Hinzman JM, Gerhardt GA, Lifshitz J. Hypersensitive glutamate signaling correlates with the development of late-onset behavioral morbidity in diffuse brain-injured circuitry. J Neurotrauma 2012; 29:187-200. [PMID: 21939393 PMCID: PMC3261793 DOI: 10.1089/neu.2011.2091] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In diffuse brain-injured rats, robust sensory sensitivity to manual whisker stimulation develops over 1 month post-injury, comparable to agitation expressed by brain-injured individuals with overstimulation. In the rat, whisker somatosensation relies on thalamocortical glutamatergic relays between the ventral posterior medial (VPM) thalamus and barrel fields of somatosensory cortex (S1BF). Using novel glutamate-selective microelectrode arrays coupled to amperometry, we test the hypothesis that disrupted glutamatergic neurotransmission underlies the whisker sensory sensitivity associated with diffuse brain injury. We report hypersensitive glutamate neurotransmission that parallels and correlates with the development of post-traumatic sensory sensitivity. Hypersensitivity is demonstrated by significant 110% increases in VPM extracellular glutamate levels, and 100% increase in potassium-evoked glutamate release in the VPM and S1BF, with no change in glutamate clearance. Further, evoked glutamate release showed 50% greater sensitivity to a calcium channel antagonist in brain-injured over uninjured VPM. In conjunction with no changes in glutamate transporter gene expression and exogenous glutamate clearance efficiency, these data support a presynaptic origin for enduring post-traumatic circuit alterations. In the anatomically-distinct whisker circuit, the injury-induced functional alterations correlate with the development of late-onset behavioral morbidity. Effective therapies to modulate presynaptic glutamate function in diffuse-injured circuits may translate into improvements in essential brain function and behavioral performance in other brain-injured circuits in rodents and in humans.
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Affiliation(s)
- Theresa Currier Thomas
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Jason M. Hinzman
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky
- Center for Microelectrode Technology, University of Kentucky College of Medicine, Lexington, Kentucky
- Morris K. Udall Parkinson's Disease Research Center of Excellence, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Greg A. Gerhardt
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky
- Center for Microelectrode Technology, University of Kentucky College of Medicine, Lexington, Kentucky
- Morris K. Udall Parkinson's Disease Research Center of Excellence, University of Kentucky College of Medicine, Lexington, Kentucky
| | - Jonathan Lifshitz
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky
- Department of Physical Medicine & Rehabilitation, University of Kentucky College of Medicine, Lexington, Kentucky
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Blaylock RL, Maroon J. Immunoexcitotoxicity as a central mechanism in chronic traumatic encephalopathy-A unifying hypothesis. Surg Neurol Int 2011; 2:107. [PMID: 21886880 PMCID: PMC3157093 DOI: 10.4103/2152-7806.83391] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 06/06/2011] [Indexed: 12/17/2022] Open
Abstract
Some individuals suffering from mild traumatic brain injuries, especially repetitive mild concussions, are thought to develop a slowly progressive encephalopathy characterized by a number of the neuropathological elements shared with various neurodegenerative diseases. A central pathological mechanism explaining the development of progressive neurodegeneration in this subset of individuals has not been elucidated. Yet, a large number of studies indicate that a process called immunoexcitotoxicity may be playing a central role in many neurodegenerative diseases including chronic traumatic encephalopathy (CTE). The term immunoexcitotoxicity was first coined by the lead author to explain the evolving pathological and neurodevelopmental changes in autism and the Gulf War Syndrome, but it can be applied to a number of neurodegenerative disorders. The interaction between immune receptors within the central nervous system (CNS) and excitatory glutamate receptors trigger a series of events, such as extensive reactive oxygen species/reactive nitrogen species generation, accumulation of lipid peroxidation products, and prostaglandin activation, which then leads to dendritic retraction, synaptic injury, damage to microtubules, and mitochondrial suppression. In this paper, we discuss the mechanism of immunoexcitotoxicity and its link to each of the pathophysiological and neurochemical events previously described with CTE, with special emphasis on the observed accumulation of hyperphosphorylated tau.
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Affiliation(s)
- Russell L Blaylock
- Theoretical Neurosciences, LLC Visiting Professor of Biology, Belhaven University, Jackson, MS 315 Rolling Meadows Rd, Ridgeland, MS 39157, USA
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Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
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Kim Y, Park YK, Cho HY, Kim J, Yoon YW. Long-term changes in expressions of spinal glutamate transporters after spinal cord injury. Brain Res 2011; 1389:194-9. [PMID: 21439271 DOI: 10.1016/j.brainres.2011.03.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 03/11/2011] [Accepted: 03/16/2011] [Indexed: 12/31/2022]
Abstract
Glutamate is a major excitatory transmitter in the central nervous system that may produce cellular injury when its concentration is abnormally increased in the synaptic cleft. Glial glutamate transporters GLAST and GLT-1, which are responsible for clearing synaptic glutamate into glial cells, play an important role in the regulation of the glutamate concentration in the synaptic cleft. However, there has been no report on long-term changes in the levels of glutamate transporters following spinal cord injury. Spinal cord injury (SCI) was induced at T12 by a New York University (NYU) impactor. Segments of the spinal cord at T9-10, L1-2, L4-5 and at the epicenter were removed after SCI, and Western blots for GLAST, GLT-1 and EAAC1 were performed. GLAST and GLT-1 were significantly decreased in the epicenter from 1day up to 8weeks after SCI. GLT-1 was significantly decreased in the spinal segments rostral to the injury site, and GLAST expression was significantly increased in the L4-5 region of the spinal cord for 8weeks. Because strategies to modulate the regulation of glutamate transporters may be applied, the present data serve as a reference for further research, although the long-term roles of glutamate transporters in pathological processes caused by SCI are not clear.
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Affiliation(s)
- Youngkyung Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul, 136-705, Republic of Korea
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Persson M, Rönnbäck L. Microglial self-defence mediated through GLT-1 and glutathione. Amino Acids 2011; 42:207-19. [PMID: 21373770 DOI: 10.1007/s00726-011-0865-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 11/27/2022]
Abstract
Glutamate is stored in synaptic vesicles in presynaptic neurons. It is released into the synaptic cleft to provide signalling to postsynaptic neurons. Normally, the astroglial glutamate transporters GLT-1 and GLAST take up glutamate to mediate a high signal-to-noise ratio in the synaptic signalling, and also to prevent excitotoxic effects by glutamate. In astrocytes, glutamate is transformed into glutamine, which is safely transported back to neurons. However, in pathological conditions, such as an ischemia or virus infection, astroglial transporters are down-regulated which could lead to excitotoxicity. Lately, it was shown that even microglia can express glutamate transporters during pathological events. Microglia have two systems for glutamate transport: GLT-1 for transport into the cells and the x (c) (-) system for transport out of the cells. We here review results from our work and others, which demonstrate that microglia in culture express GLT-1, but not GLAST, and transport glutamate from the extracellular space. We also show that TNF-α can induce increased microglial GLT-1 expression, possibly associating the expression with inflammatory systems. Furthermore, glutamate taken up through GLT-1 may be used for direct incorporation into glutathione and to fuel the intracellular glutamate pool to allow cystine uptake through the x (c) (-) system. This can lead to a defence against oxidative stress and have an antiviral function.
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Affiliation(s)
- Mikael Persson
- Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Per Dubbsgatan 14, 1tr, 41345, Gothenburg, Sweden
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Gras G, Samah B, Hubert A, Léone C, Porcheray F, Rimaniol AC. EAAT expression by macrophages and microglia: still more questions than answers. Amino Acids 2011; 42:221-9. [PMID: 21373769 DOI: 10.1007/s00726-011-0866-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 01/07/2023]
Abstract
Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It may induce excitotoxicity and also compete with cystine for the use of the cystine-glutamate exchanger, blocking glutathione neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20% of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood. Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological conditions as well as its outcome.
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Affiliation(s)
- Gabriel Gras
- Division of Immuno-Virology, Institute of Emerging Diseases and Innovative Therapies, UMR E1 CEA DSV/IMETI/SIV and University Paris South-Paris 11, 18, route du Panorama, 92265, Fontenay-aux Roses, France.
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