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Rabeh N, Hajjar B, Maraka JO, Sammanasunathan AF, Khan M, Alkhaaldi SMI, Mansour S, Almheiri RT, Hamdan H, Abd-Elrahman KS. Targeting mGluR group III for the treatment of neurodegenerative diseases. Biomed Pharmacother 2023; 168:115733. [PMID: 37862967 DOI: 10.1016/j.biopha.2023.115733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/11/2023] [Accepted: 10/13/2023] [Indexed: 10/22/2023] Open
Abstract
Glutamate, an excitatory neurotransmitter, is essential for neuronal function, and it acts on ionotropic or metabotropic glutamate receptors (mGluRs). A disturbance in glutamatergic signaling is a hallmark of many neurodegenerative diseases. Developing disease-modifying treatments for neurodegenerative diseases targeting glutamate receptors is a promising avenue. The understudied group III mGluR 4, 6-8 are commonly found in the presynaptic membrane, and their activation inhibits glutamate release. Thus, targeted mGluRs therapies could aid in treating neurodegenerative diseases. This review describes group III mGluRs and their pharmacological ligands in the context of amyotrophic lateral sclerosis, Parkinson's, Alzheimer's, and Huntington's diseases. Attempts to evaluate the efficacy of these drugs in clinical trials are also discussed. Despite a growing list of group III mGluR-specific pharmacological ligands, research on the use of these drugs in neurodegenerative diseases is limited, except for Parkinson's disease. Future efforts should focus on delineating the contribution of group III mGluR to neurodegeneration and developing novel ligands with superior efficacy and a favorable side effect profile for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Nadia Rabeh
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Baraa Hajjar
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Jude O Maraka
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Ashwin F Sammanasunathan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Mohammed Khan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Saif M I Alkhaaldi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Samy Mansour
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Rashed T Almheiri
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates
| | - Hamdan Hamdan
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Healthcare Engineering Innovation Center (HEIC), Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates
| | - Khaled S Abd-Elrahman
- Department of Anesthesiology, Pharmacology and Therapeutics, and Djavad Mowafaghian Center for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada; Department of Pharmacology and Therapeutics, College of Medicine and Health Science, Khalifa University, Abu Dhabi 127788, United Arab Emirates; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt.
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Gautam D, Naik UP, Naik MU, Yadav SK, Chaurasia RN, Dash D. Glutamate Receptor Dysregulation and Platelet Glutamate Dynamics in Alzheimer's and Parkinson's Diseases: Insights into Current Medications. Biomolecules 2023; 13:1609. [PMID: 38002291 PMCID: PMC10669830 DOI: 10.3390/biom13111609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
Two of the most prevalent neurodegenerative disorders (NDDs), Alzheimer's disease (AD) and Parkinson's disease (PD), present significant challenges to healthcare systems worldwide. While the etiologies of AD and PD differ, both diseases share commonalities in synaptic dysfunction, thereby focusing attention on the role of neurotransmitters. The possible functions that platelets may play in neurodegenerative illnesses including PD and AD are becoming more acknowledged. In AD, platelets have been investigated for their ability to generate amyloid-ß (Aß) peptides, contributing to the formation of neurotoxic plaques. Moreover, platelets are considered biomarkers for early AD diagnosis. In PD, platelets have been studied for their involvement in oxidative stress and mitochondrial dysfunction, which are key factors in the disease's pathogenesis. Emerging research shows that platelets, which release glutamate upon activation, also play a role in these disorders. Decreased glutamate uptake in platelets has been observed in Alzheimer's and Parkinson's patients, pointing to a systemic dysfunction in glutamate handling. This paper aims to elucidate the critical role that glutamate receptors play in the pathophysiology of both AD and PD. Utilizing data from clinical trials, animal models, and cellular studies, we reviewed how glutamate receptors dysfunction contributes to neurodegenerative (ND) processes such as excitotoxicity, synaptic loss, and cognitive impairment. The paper also reviews all current medications including glutamate receptor antagonists for AD and PD, highlighting their mode of action and limitations. A deeper understanding of glutamate receptor involvement including its systemic regulation by platelets could open new avenues for more effective treatments, potentially slowing disease progression and improving patient outcomes.
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Affiliation(s)
- Deepa Gautam
- Center for Advanced Research on Platelet Signaling and Thrombosis Biology, Department of Biochemistry, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
- The Cardeza Foundation for Hematologic Research, Center for Hemostasis, Thrombosis and Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA; (U.P.N.); (M.U.N.); (S.K.Y.)
| | - Ulhas P. Naik
- The Cardeza Foundation for Hematologic Research, Center for Hemostasis, Thrombosis and Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA; (U.P.N.); (M.U.N.); (S.K.Y.)
| | - Meghna U. Naik
- The Cardeza Foundation for Hematologic Research, Center for Hemostasis, Thrombosis and Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA; (U.P.N.); (M.U.N.); (S.K.Y.)
| | - Santosh K. Yadav
- The Cardeza Foundation for Hematologic Research, Center for Hemostasis, Thrombosis and Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA; (U.P.N.); (M.U.N.); (S.K.Y.)
| | - Rameshwar Nath Chaurasia
- The Department of Neurology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India;
| | - Debabrata Dash
- Center for Advanced Research on Platelet Signaling and Thrombosis Biology, Department of Biochemistry, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
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3
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Grovola MR, von Reyn C, Loane DJ, Cullen DK. Understanding microglial responses in large animal models of traumatic brain injury: an underutilized resource for preclinical and translational research. J Neuroinflammation 2023; 20:67. [PMID: 36894951 PMCID: PMC9999644 DOI: 10.1186/s12974-023-02730-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/13/2023] [Indexed: 03/11/2023] Open
Abstract
Traumatic brain injury (TBI) often results in prolonged or permanent brain dysfunction with over 2.8 million affected annually in the U.S., including over 56,000 deaths, with over 5 million total survivors exhibiting chronic deficits. Mild TBI (also known as concussion) accounts for over 75% of all TBIs every year. Mild TBI is a heterogeneous disorder, and long-term outcomes are dependent on the type and severity of the initial physical event and compounded by secondary pathophysiological consequences, such as reactive astrocytosis, edema, hypoxia, excitotoxicity, and neuroinflammation. Neuroinflammation has gained increasing attention for its role in secondary injury as inflammatory pathways can have both detrimental and beneficial roles. For example, microglia-resident immune cells of the central nervous system (CNS)-influence cell death pathways and may contribute to progressive neurodegeneration but also aid in debris clearance and neuroplasticity. In this review, we will discuss the acute and chronic role of microglia after mild TBI, including critical protective responses, deleterious effects, and how these processes vary over time. These descriptions are contextualized based on interspecies variation, sex differences, and prospects for therapy. We also highlight recent work from our lab that was the first to describe microglial responses out to chronic timepoints after diffuse mild TBI in a clinically relevant large animal model. The scaled head rotational acceleration of our large animal model, paired with the gyrencephalic architecture and appropriate white:gray matter ratio, allows us to produce pathology with the same anatomical patterns and distribution of human TBI, and serves as an exemplary model to examine complex neuroimmune response post-TBI. An improved understanding of microglial influences in TBI could aid in the development of targeted therapeutics to accentuate positive effects while attenuating detrimental post-injury responses over time.
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Affiliation(s)
- Michael R Grovola
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA.,Department of Neurosurgery, Center for Brain Injury & Repair, University of Pennsylvania, 105E Hayden Hall/3320 Smith Walk, Philadelphia, PA, 19104, USA
| | - Catherine von Reyn
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA.,Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - David J Loane
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland.,Department of Anesthesiology and Shock, Trauma, and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA
| | - D Kacy Cullen
- Center for Neurotrauma, Neurodegeneration & Restoration, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA. .,Department of Neurosurgery, Center for Brain Injury & Repair, University of Pennsylvania, 105E Hayden Hall/3320 Smith Walk, Philadelphia, PA, 19104, USA. .,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA.
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4
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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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5
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Microglial Activation in Metal Neurotoxicity: Impact in Neurodegenerative Diseases. BIOMED RESEARCH INTERNATIONAL 2023; 2023:7389508. [PMID: 36760476 PMCID: PMC9904912 DOI: 10.1155/2023/7389508] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/18/2023] [Accepted: 01/23/2023] [Indexed: 02/04/2023]
Abstract
Neurodegenerative processes encompass a large variety of diseases with different pathological patterns and clinical features, such as Alzheimer's and Parkinson's diseases. Exposure to metals has been hypothesized to increase oxidative stress in brain cells leading to cell death and neurodegeneration. Neurotoxicity of metals has been demonstrated by several in vitro and in vivo experimental studies, and most probably, each metal has its specific pathway to trigger cell death. As a result, exposure to essential metals, such as manganese, iron, copper, zinc, and cobalt, and nonessential metals, including lead, aluminum, and cadmium, perturbs metal homeostasis at the cellular and organism levels leading to neurodegeneration. In this contribution, a comprehensive review of the molecular mechanisms by which metals affect microglia physiology and signaling properties is presented. Furthermore, studies that validate the disruption of microglia activation pathways as an essential mechanism of metal toxicity that can contribute to neurodegenerative disease are also presented and discussed.
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6
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Kwan C, Kang W, Kim E, Belliveau S, Frouni I, Huot P. Metabotropic glutamate receptors in Parkinson's disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:1-31. [PMID: 36868628 DOI: 10.1016/bs.irn.2022.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Parkinson's disease (PD) is a complex disorder that leads to alterations in multiple neurotransmitter systems, notably glutamate. As such, several drugs acting at glutamatergic receptors have been assessed to alleviate the manifestation of PD and treatment-related complications, culminating with the approval of the N-methyl-d-aspartate (NMDA) antagonist amantadine for l-3,4-dihydroxyphenylalanine (l-DOPA)-induced dyskinesia. Glutamate elicits its actions through several ionotropic and metabotropic (mGlu) receptors. There are 8 sub-types of mGlu receptors, with sub-types 4 (mGlu4) and 5 (mGlu5) modulators having been tested in the clinic for endpoints pertaining to PD, while sub-types 2 (mGlu2) and 3 (mGlu3) have been investigated in pre-clinical settings. In this book chapter, we provide an overview of mGlu receptors in PD, with a focus on mGlu5, mGlu4, mGlu2 and mGlu3 receptors. For each sub-type, we review, when applicable, their anatomical localization and possible mechanisms underlying their efficacy for specific disease manifestation or treatment-induced complications. We then summarize the findings of pre-clinical studies and clinical trials with pharmacological agents and discuss the potential strengths and limitations of each target. We conclude by offering some perspectives on the potential use of mGlu modulators in the treatment of PD.
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Affiliation(s)
- Cynthia Kwan
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada
| | - Woojin Kang
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada
| | - Esther Kim
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada
| | - Sébastien Belliveau
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada
| | - Imane Frouni
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada; Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada
| | - Philippe Huot
- Neurodegenerative Disease Group, Montreal Neurological Institute-Hospital (The Neuro), Montreal, QC, Canada; Département de Pharmacologie et Physiologie, Université de Montréal, Montreal, QC, Canada; Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; Movement Disorder Clinic, Division of Neurology, Department of Neurosciences, McGill University Health Centre, Montreal, QC, Canada.
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7
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Wu Y, Eisel UL. Microglia-Astrocyte Communication in Alzheimer's Disease. J Alzheimers Dis 2023; 95:785-803. [PMID: 37638434 PMCID: PMC10578295 DOI: 10.3233/jad-230199] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2023] [Indexed: 08/29/2023]
Abstract
Microglia and astrocytes are regarded as active participants in the central nervous system under various neuropathological conditions, including Alzheimer's disease (AD). Both microglia and astrocyte activation have been reported to occur with a spatially and temporarily distinct pattern. Acting as a double-edged sword, glia-mediated neuroinflammation may be both detrimental and beneficial to the brain. In a variety of neuropathologies, microglia are activated before astrocytes, which facilitates astrocyte activation. Yet reactive astrocytes can also prevent the activation of adjacent microglia in addition to helping them become activated. Studies describe changes in the genetic profile as well as cellular and molecular responses of these two types of glial cells that contribute to dysfunctional immune crosstalk in AD. In this paper, we construct current knowledge of microglia-astrocyte communication, highlighting the multifaceted functions of microglia and astrocytes and their role in AD. A thorough comprehension of microglia-astrocyte communication could hasten the creation of novel AD treatment approaches.
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Affiliation(s)
- Yingying Wu
- Department of Molecular Neurobiology, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
- Department of Neurology, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan, China
| | - Ulrich L.M. Eisel
- Department of Molecular Neurobiology, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands
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8
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Hoglund BK, Carfagno V, Olive MF, Leyrer-Jackson JM. Metabotropic glutamate receptors and cognition: From underlying plasticity and neuroprotection to cognitive disorders and therapeutic targets. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:367-413. [PMID: 36868635 DOI: 10.1016/bs.irn.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors that play pivotal roles in mediating the activity of neurons and other cell types within the brain, communication between cell types, synaptic plasticity, and gene expression. As such, these receptors play an important role in a number of cognitive processes. In this chapter, we discuss the role of mGlu receptors in various forms of cognition and their underlying physiology, with an emphasis on cognitive dysfunction. Specifically, we highlight evidence that links mGlu physiology to cognitive dysfunction across brain disorders including Parkinson's disease, Alzheimer's disease, Fragile X syndrome, post-traumatic stress disorder, and schizophrenia. We also provide recent evidence demonstrating that mGlu receptors may elicit neuroprotective effects in particular disease states. Lastly, we discuss how mGlu receptors can be targeted utilizing positive and negative allosteric modulators as well as subtype specific agonists and antagonist to restore cognitive function across these disorders.
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Affiliation(s)
- Brandon K Hoglund
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States
| | - Vincent Carfagno
- School of Medicine, Midwestern University, Glendale, AZ, United States
| | - M Foster Olive
- Department of Psychology, Arizona State University, Tempe, AZ, United States
| | - Jonna M Leyrer-Jackson
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States.
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de Lima IB, Ribeiro FM. The Implication of Glial Metabotropic Glutamate Receptors in Alzheimer's Disease. Curr Neuropharmacol 2023; 21:164-182. [PMID: 34951388 PMCID: PMC10190153 DOI: 10.2174/1570159x20666211223140303] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 11/22/2022] Open
Abstract
Alzheimer's disease (AD) was first identified more than 100 years ago, yet aspects pertaining to its origin and the mechanisms underlying disease progression are not well known. To this date, there is no therapeutic approach or disease-modifying drug that could halt or at least delay disease progression. Until recently, glial cells were seen as secondary actors in brain homeostasis. Although this view was gradually refuted and the relevance of glial cells for the most diverse brain functions such as synaptic plasticity and neurotransmission was vastly proved, many aspects of its functioning, as well as its role in pathological conditions, remain poorly understood. Metabotropic glutamate receptors (mGluRs) in glial cells were shown to be involved in neuroinflammation and neurotoxicity. Besides its relevance for glial function, glutamatergic receptors are also central in the pathology of AD, and recent studies have shown that glial mGluRs play a role in the establishment and progression of AD. AD-related alterations in Ca2+ signalling, APP processing, and Aβ load, as well as AD-related neurodegeneration, are influenced by glial mGluRs. However, different types of mGluRs play different roles, depending on the cell type and brain region that is being analysed. Therefore, in this review, we focus on the current understanding of glial mGluRs and their implication in AD, providing an insight for future therapeutics and identifying existing research gaps worth investigating.
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Affiliation(s)
- Izabella B.Q. de Lima
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fabíola M. Ribeiro
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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10
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Mao LM, Mathur N, Shah K, Wang JQ. Roles of metabotropic glutamate receptor 8 in neuropsychiatric and neurological disorders. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:349-366. [PMID: 36868634 PMCID: PMC10162486 DOI: 10.1016/bs.irn.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors. Among eight mGlu subtypes (mGlu1-8), mGlu8 has drawn increasing attention. This subtype is localized to the presynaptic active zone of neurotransmitter release and is among the mGlu subtypes with high affinity for glutamate. As a Gi/o-coupled autoreceptor, mGlu8 inhibits glutamate release to maintain homeostasis of glutamatergic transmission. mGlu8 receptors are expressed in limbic brain regions and play a pivotal role in modulating motivation, emotion, cognition, and motor functions. Emerging evidence emphasizes the increasing clinical relevance of abnormal mGlu8 activity. Studies using mGlu8 selective agents and knockout mice have revealed the linkage of mGlu8 receptors to multiple neuropsychiatric and neurological disorders, including anxiety, epilepsy, Parkinson's disease, drug addiction, and chronic pain. Expression and function of mGlu8 receptors in some limbic structures undergo long-lasting adaptive changes in animal models of these disorders, which may contribute to the remodeling of glutamatergic transmission critical for the pathogenesis and symptomatology of brain illnesses. This review summarizes the current understanding of mGlu8 biology and the possible involvement of the receptor in several common psychiatric and neurological disorders.
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Affiliation(s)
- Li-Min Mao
- Department of Biomedical Sciences, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, United States
| | - Nirav Mathur
- Department of Anesthesiology, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, United States
| | - Karina Shah
- Department of Biomedical Sciences, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, United States
| | - John Q Wang
- Department of Biomedical Sciences, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, United States; Department of Anesthesiology, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, United States.
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11
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Domin H. Group III metabotropic glutamate receptors as promising targets for neuroprotective therapy: Particular emphasis on the role of mGlu4 and mGlu7 receptors. Pharmacol Biochem Behav 2022; 219:173452. [PMID: 36030890 DOI: 10.1016/j.pbb.2022.173452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/11/2022] [Accepted: 08/19/2022] [Indexed: 11/25/2022]
Abstract
There is still no effective treatment for central nervous system (CNS) pathologies, including cerebral ischemia, neurotrauma, and neurodegenerative diseases in which the Glu/GABA balance is disturbed with associated excitotoxicity. It is thus important to search for new efficacious therapeutic strategies. Preclinical studies on the role of metabotropic glutamate receptors (mGluRs) in neuroprotection conducted over the years show that these receptors may have therapeutic potential in these CNS disorders. However, clinical trials, especially for treating Parkinson's disease, have been unsatisfactory. This review focuses on the specific role of group III mGluRs in neuroprotection in experimental in vitro and in vivo models of excitotoxicity/neurotoxicity using neurotoxins as well as ischemia, traumatic brain injury, and neurodegenerative diseases such as Parkinson's disease, Alzheimer's diseases, and multiple sclerosis. The review highlights recent preclinical studies in which group III mGluR ligands (especially those acting at mGluR4 or mGluR7) were administered after damage, thus emphasizing the importance of the therapeutic time window in the treatment of ischemic stroke and traumatic brain injury. From a clinical standpoint, the review also highlights studies using group III mGluR agonists with favorable neuroprotective efficacy (histological and functional) in experimental ischemic stroke, including healthy normotensive and-hypertensive rats. This review also summarizes possible mechanisms underlying the neuroprotective activity of the group III mGluR ligands, which may be helpful in developing more effective and safe therapeutic strategies. Therefore, to fully assess the role of these receptors in neuroprotection, it is necessary to uncover new selective ligands, primarily those stimulating mGlu4 and mGlu7 receptors.
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Affiliation(s)
- Helena Domin
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Neurobiology, 12 Smętna Street, 31-343 Kraków, Poland.
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12
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Palazzo E, Boccella S, Marabese I, Perrone M, Belardo C, Iannotta M, Scuteri D, De Dominicis E, Pagano M, Infantino R, Bagetta G, Maione S. Homo-AMPA in the periaqueductal grey modulates pain and rostral ventromedial medulla activity in diabetic neuropathic mice. Neuropharmacology 2022; 212:109047. [DOI: 10.1016/j.neuropharm.2022.109047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 02/22/2022] [Accepted: 03/26/2022] [Indexed: 12/21/2022]
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13
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Chen CC, Brumberg JC. Sensory Experience as a Regulator of Structural Plasticity in the Developing Whisker-to-Barrel System. Front Cell Neurosci 2022; 15:770453. [PMID: 35002626 PMCID: PMC8739903 DOI: 10.3389/fncel.2021.770453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 11/22/2021] [Indexed: 12/28/2022] Open
Abstract
Cellular structures provide the physical foundation for the functionality of the nervous system, and their developmental trajectory can be influenced by the characteristics of the external environment that an organism interacts with. Historical and recent works have determined that sensory experiences, particularly during developmental critical periods, are crucial for information processing in the brain, which in turn profoundly influence neuronal and non-neuronal cortical structures that subsequently impact the animals' behavioral and cognitive outputs. In this review, we focus on how altering sensory experience influences normal/healthy development of the central nervous system, particularly focusing on the cerebral cortex using the rodent whisker-to-barrel system as an illustrative model. A better understanding of structural plasticity, encompassing multiple aspects such as neuronal, glial, and extra-cellular domains, provides a more integrative view allowing for a deeper appreciation of how all aspects of the brain work together as a whole.
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Affiliation(s)
- Chia-Chien Chen
- Department of Psychology, Queens College City University of New York, Flushing, NY, United States.,Department of Neuroscience, Duke Kunshan University, Suzhou, China
| | - Joshua C Brumberg
- Department of Psychology, Queens College City University of New York, Flushing, NY, United States.,The Biology (Neuroscience) and Psychology (Behavioral and Cognitive Neuroscience) PhD Programs, The Graduate Center, The City University of New York, New York, NY, United States
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14
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Sood A, Preeti K, Fernandes V, Khatri DK, Singh SB. Glia: A major player in glutamate-GABA dysregulation-mediated neurodegeneration. J Neurosci Res 2021; 99:3148-3189. [PMID: 34748682 DOI: 10.1002/jnr.24977] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/18/2021] [Accepted: 09/21/2021] [Indexed: 12/16/2022]
Abstract
The imbalance between glutamate and γ-aminobutyric acid (GABA) results in the loss of synaptic strength leading to neurodegeneration. The dogma on the field considered neurons as the main players in this excitation-inhibition (E/I) balance. However, current strategies focusing only on neurons have failed to completely understand this condition, bringing up the importance of glia as an alternative modulator for neuroinflammation as glia alter the activity of neurons and is a source of both neurotrophic and neurotoxic factors. This review's primary goal is to illustrate the role of glia over E/I balance in the central nervous system and its interaction with neurons. Rather than focusing only on the neuronal targets, we take a deeper look at glial receptors and proteins that could also be explored as drug targets, as they are early responders to neurotoxic insults. This review summarizes the neuron-glia interaction concerning GABA and glutamate, possible targets, and its involvement in the E/I imbalance in neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis.
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Affiliation(s)
- Anika Sood
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, India
| | - Kumari Preeti
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, India
| | - Valencia Fernandes
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, India
| | - Dharmendra Kumar Khatri
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, India
| | - Shashi Bala Singh
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad, India
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15
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De Schepper S, Crowley G, Hong S. Understanding microglial diversity and implications for neuronal function in health and disease. Dev Neurobiol 2021; 81:507-523. [PMID: 32757416 PMCID: PMC8438703 DOI: 10.1002/dneu.22777] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 06/21/2020] [Accepted: 07/31/2020] [Indexed: 12/22/2022]
Abstract
Genetic data implicate microglia as central players in brain health and disease, urging the need to better understand what microglia do in the brain. Microglia are critical partners in neuronal wiring and function during development and disease. Emerging literature suggests that microglia have diverse functional roles, raising the intriguing question of which functions of microglia become impaired in disease to undermine proper neuronal function. It is also becoming increasingly clear that microglia exist in heterogeneous cell states. Microglial cell states appear context-dependent, that is, age, sex, location, and health of their microenvironment; these are further influenced by external signaling factors including gut microbiota and lipid metabolites. These data altogether suggest that microglia exist in functional clusters that impact, and are impacted by, surrounding neuronal microenvironment. However, we still lack understanding of how we can translate microglia cell states into function. Here, we summarize the state-of-the-art on the diverse functions of microglia in relation to neuronal health. Then, we discuss heterogeneity during developing, healthy adult and diseased brains, and whether this may be predetermined by origin and/or regulated by local milieu. Finally, we propose that it is critical to gain high-resolution functional discernment into microglia-neuron interactions while preserving the spatial architecture of the tissue. Such insight will reveal specific targets for biomarker and therapeutic development toward microglia-neuron crosstalk in disease.
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Affiliation(s)
| | - Gerard Crowley
- UK Dementia Research InstituteUniversity College LondonLondonUK
| | - Soyon Hong
- UK Dementia Research InstituteUniversity College LondonLondonUK
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16
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Racki V, Marcelic M, Stimac I, Petric D, Kucic N. Effects of Haloperidol, Risperidone, and Aripiprazole on the Immunometabolic Properties of BV-2 Microglial Cells. Int J Mol Sci 2021; 22:ijms22094399. [PMID: 33922377 PMCID: PMC8122792 DOI: 10.3390/ijms22094399] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 02/07/2023] Open
Abstract
Microglial cells are resident macrophages in the brain that have been implicated in the pathophysiology of schizophrenia. There is a lack of studies covering the effects of antipsychotics on microglial cells. The current literature points to a possible anti-inflammatory action without clear mechanisms of action. The aim of this study is to characterize the effects of haloperidol, risperidone and aripiprazole on BV-2 microglial cells in in vitro conditions. We have used immunofluorescence and flow cytometry to analyze the classical pro and anti-inflammatory markers, while a real-time metabolic assay (Seahorse) was used to assess metabolic function. We analyzed the expression of p70S6K to evaluate the mTOR pathway activity with Western blot. In this study, we demonstrate the varying effects of haloperidol, risperidone and aripiprazole administration in BV-2 microglial cells. All three tested antipsychotics were successful in reducing the pro-inflammatory action of microglial cells, although only aripiprazole increased the expression of anti-inflammatory markers. Most significant differences in the possible mechanisms of action were seen in the real-time metabolic assays and in the mTORC1 signaling pathway activity, with aripiprazole being the only antipsychotic to reduce the mTORC1 activity. Our results shed some new light on the effects of haloperidol, risperidone and aripiprazole action in microglial cells, and reveal a novel possible mechanism of action for aripiprazole.
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Affiliation(s)
- Valentino Racki
- Department of Neurology, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia
- Correspondence:
| | - Marina Marcelic
- Department of Physiology and Immunology, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia; (M.M.); (I.S.); (N.K.)
| | - Igor Stimac
- Department of Physiology and Immunology, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia; (M.M.); (I.S.); (N.K.)
| | - Daniela Petric
- Department of Psychiatry, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia;
| | - Natalia Kucic
- Department of Physiology and Immunology, Medical Faculty, University of Rijeka, 51000 Rijeka, Croatia; (M.M.); (I.S.); (N.K.)
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17
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Gipson CD, Rawls S, Scofield MD, Siemsen BM, Bondy EO, Maher EE. Interactions of neuroimmune signaling and glutamate plasticity in addiction. J Neuroinflammation 2021; 18:56. [PMID: 33612110 PMCID: PMC7897396 DOI: 10.1186/s12974-021-02072-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 01/05/2021] [Indexed: 02/28/2023] Open
Abstract
Chronic use of drugs of abuse affects neuroimmune signaling; however, there are still many open questions regarding the interactions between neuroimmune mechanisms and substance use disorders (SUDs). Further, chronic use of drugs of abuse can induce glutamatergic changes in the brain, but the relationship between the glutamate system and neuroimmune signaling in addiction is not well understood. Therefore, the purpose of this review is to bring into focus the role of neuroimmune signaling and its interactions with the glutamate system following chronic drug use, and how this may guide pharmacotherapeutic treatment strategies for SUDs. In this review, we first describe neuroimmune mechanisms that may be linked to aberrant glutamate signaling in addiction. We focus specifically on the nuclear factor-kappa B (NF-κB) pathway, a potentially important neuroimmune mechanism that may be a key player in driving drug-seeking behavior. We highlight the importance of astroglial-microglial crosstalk, and how this interacts with known glutamatergic dysregulations in addiction. Then, we describe the importance of studying non-neuronal cells with unprecedented precision because understanding structure-function relationships in these cells is critical in understanding their role in addiction neurobiology. Here we propose a working model of neuroimmune-glutamate interactions that underlie drug use motivation, which we argue may aid strategies for small molecule drug development to treat substance use disorders. Together, the synthesis of this review shows that interactions between glutamate and neuroimmune signaling may play an important and understudied role in addiction processes and may be critical in developing more efficacious pharmacotherapies to treat SUDs.
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Affiliation(s)
- Cassandra D Gipson
- Department of Family and Community Medicine, University of Kentucky, 741 S. Limestone, BBSRB, Room 363, Lexington, KY, 40536-0509, USA.
| | - Scott Rawls
- Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | - Michael D Scofield
- Department of Anesthesiology, Medical University of South Carolina, Charleston, USA
- Department of Neuroscience, Medical University of South Carolina, Charleston, USA
| | - Benjamin M Siemsen
- Department of Anesthesiology, Medical University of South Carolina, Charleston, USA
| | - Emma O Bondy
- Department of Family and Community Medicine, University of Kentucky, 741 S. Limestone, BBSRB, Room 363, Lexington, KY, 40536-0509, USA
| | - Erin E Maher
- Department of Family and Community Medicine, University of Kentucky, 741 S. Limestone, BBSRB, Room 363, Lexington, KY, 40536-0509, USA
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18
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Zinni M, Mairesse J, Pansiot J, Fazio F, Iacovelli L, Antenucci N, Orlando R, Nicoletti F, Vaiman D, Baud O. mGlu3 receptor regulates microglial cell reactivity in neonatal rats. J Neuroinflammation 2021; 18:13. [PMID: 33407565 PMCID: PMC7789385 DOI: 10.1186/s12974-020-02049-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Perinatal inflammation is a key factor of brain vulnerability in neonates born preterm or with intra-uterine growth restriction (IUGR), two leading conditions associated with brain injury and responsible for neurocognitive and behavioral disorders. Systemic inflammation is recognized to activate microglia, known to be the critical modulators of brain vulnerability. Although some evidence supports a role for metabotropic glutamate receptor 3 (mGlu3 receptor) in modulation of neuroinflammation, its functions are still unknown in the developing microglia. METHODS We used a double-hit rat model of perinatal brain injury induced by a gestational low-protein diet combined with interleukin-1β injections (LPD/IL-1β), mimicking both IUGR and prematurity-related inflammation. The effect of LPD/IL-1β on mGlu3 receptor expression and the effect of mGlu3 receptor modulation on microglial reactivity were investigated using a combination of pharmacological, histological, and molecular and genetic approaches. RESULTS Exposure to LPD/IL-1β significantly downregulated Grm3 gene expression in the developing microglia. Both transcriptomic analyses and pharmacological modulation of mGlu3 receptor demonstrated its central role in the control of inflammation in resting and activated microglia. Microglia reactivity to inflammatory challenge induced by LPD/IL-1β exposure was reduced by an mGlu3 receptor agonist. Conversely, both specific pharmacological blockade, siRNA knock-down, and genetic knock-out of mGlu3 receptors mimicked the pro-inflammatory phenotype observed in microglial cells exposed to LPD/IL-1β. CONCLUSIONS Overall, these data show that Grm3 plays a central role in the regulation of microglial reactivity in the immature brain. Selective pharmacological activation of mGlu3 receptors may prevent inflammatory-induced perinatal brain injury.
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Affiliation(s)
- Manuela Zinni
- Inserm UMR1141 NeuroDiderot, Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Jérôme Mairesse
- Inserm UMR1141 NeuroDiderot, Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France.,Laboratory of Child Growth and Development, University of Geneva, Geneva, Switzerland
| | - Julien Pansiot
- Inserm UMR1141 NeuroDiderot, Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France
| | | | - Luisa Iacovelli
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Nico Antenucci
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Rosamaria Orlando
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy.,Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Daniel Vaiman
- Institut Cochin, Inserm U1016, UMR8104 CNRS, Paris, France
| | - Olivier Baud
- Inserm UMR1141 NeuroDiderot, Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France. .,Laboratory of Child Growth and Development, University of Geneva, Geneva, Switzerland. .,Division of Neonatology and Pediatric Intensive Care, Children's University Hospital of Geneva, Geneva, Switzerland.
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19
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Selective activation of metabotropic glutamate receptor 7 blocks paclitaxel-induced acute neuropathic pain and suppresses spinal glial reactivity in rats. Psychopharmacology (Berl) 2021; 238:107-119. [PMID: 33089875 DOI: 10.1007/s00213-020-05662-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 09/10/2020] [Indexed: 12/30/2022]
Abstract
RATIONALE Paclitaxel-induced acute pain syndrome (P-APS), characterized by deep muscle aches and arthralgia, occurs in more than 70% of patients who receive paclitaxel. P-APS can be debilitating for patients and lead to reductions and discontinuation of potentially curable therapy. Despite being relatively common in clinical practice, no clear treatment exists for P-APS and the underlying mechanisms remain poorly defined. Regulation of glutamatergic transmission by metabotropic glutamate receptors (mGluRs) has received growing attention with respect to its role in neuropathic pain. To our knowledge, no study has been conducted on alterations and functions of group III mGluR7 signaling in P-APS. OBJECTIVES In the present study, we determined whether a single administration of paclitaxel induces glutamatergic alterations and whether mGluR7 activation blocks paclitaxel-induced neuropathic pain by suppressing glial reactivity in the spinal cord. RESULTS A single paclitaxel injection dose-dependently induced acute mechanical and thermal hypersensitivity, and was associated with increased glutamate level accompanied by reduction in mGluR7 expression in the spinal cord. Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocked the development of paclitaxel-induced acute mechanical and thermal hypersensitivity, without affecting the normal pain behavior of control rats. Moreover, activation of mGluR7 by AMN082 inhibited glial reactivity and decreased pro-inflammatory cytokine release during P-APS. Abortion of spinal glial reaction to paclitaxel alleviated paclitaxel-induced acute mechanical and thermal hypersensitivity. CONCLUSIONS There results support the hypothesis that spinal mGluR7 signaling plays an important role in P-APS; Selective activation of mGluR7 by its positive allosteric modulator, AMN082, blocks P-APS in part by reducing spinal glial reactivity and neuroinflammatory process.
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20
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Mesquida-Veny F, Del Río JA, Hervera A. Macrophagic and microglial complexity after neuronal injury. Prog Neurobiol 2020; 200:101970. [PMID: 33358752 DOI: 10.1016/j.pneurobio.2020.101970] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/12/2020] [Accepted: 12/06/2020] [Indexed: 12/14/2022]
Abstract
Central nervous system (CNS) injuries do not heal properly in contrast to normal tissue repair, in which functional recovery typically occurs. The reason for this dichotomy in wound repair is explained in part by macrophage and microglial malfunction, affecting both the extrinsic and intrinsic barriers to appropriate axonal regeneration. In normal healing tissue, macrophages promote the repair of injured tissue by regulating transitions through different phases of the healing response. In contrast, inflammation dominates the outcome of CNS injury, often leading to secondary damage. Therefore, an understanding of the molecular mechanisms underlying this dichotomy is critical to advance in neuronal repair therapies. Recent studies highlight the plasticity and complexity of macrophages and microglia beyond the classical view of the M1/M2 polarization paradigm. This plasticity represents an in vivo continuous spectrum of phenotypes with overlapping functions and markers. Moreover, macrophage and microglial plasticity affect many events essential for neuronal regeneration after injury, such as myelin and cell debris clearance, inflammation, release of cytokines, and trophic factors, affecting both intrinsic neuronal properties and extracellular matrix deposition. Until recently, this complexity was overlooked in the translation of therapies modulating these responses for the treatment of neuronal injuries. However, recent studies have shed important light on the underlying molecular mechanisms of this complexity and its transitions and effects on regenerative events. Here we review the complexity of macrophages and microglia after neuronal injury and their roles in regeneration, as well as the underlying molecular mechanisms, and we discuss current challenges and future opportunities for treatment.
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Affiliation(s)
- Francina Mesquida-Veny
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain; Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - José Antonio Del Río
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain; Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Arnau Hervera
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Spain; Institute of Neuroscience, University of Barcelona, 08028 Barcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain.
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21
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Stolero N, Frenkel D. The dialog between neurons and microglia in Alzheimer's disease: The neurotransmitters view. J Neurochem 2020; 158:1412-1424. [PMID: 33314073 DOI: 10.1111/jnc.15262] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 11/12/2020] [Accepted: 12/04/2020] [Indexed: 02/06/2023]
Abstract
Microglia play a vital role in maintaining brain homeostasis. Their continuous sensing of surrounding micro-environments is crucial for their activity. Cross talk between specific neurons and microglia might occur through specific neurotransmitter receptors on microglia. Impairment with this interaction might result in pathological activity of microglia against potential insults. The reason for this activity in many neurodegenerative diseases such as Alzheimer's disease (AD) is not known. However, several papers report of the effects of different neurotransmitter agonists on microglial cells function that relate to their activity in AD. This review aims to summarize those works and to raise potential fundamental questions for future research.
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Affiliation(s)
- Nofar Stolero
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics School, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Dan Frenkel
- Department of Neurobiology, School of Neurobiology, Biochemistry and Biophysics School, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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22
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Palazzo E, Boccella S, Marabese I, Pierretti G, Guida F, Maione S. The Cold Case of Metabotropic Glutamate Receptor 6: Unjust Detention in the Retina? Curr Neuropharmacol 2020; 18:120-125. [PMID: 31573889 PMCID: PMC7324884 DOI: 10.2174/1570159x17666191001141849] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/20/2019] [Accepted: 09/29/2019] [Indexed: 02/03/2023] Open
Abstract
It is a common opinion that metabotropic glutamate receptor subtype 6 (mGluR6) is expressed exclusively in the retina, and in particular in the dendrites of ON-bipolar cells. Glutamate released in darkness from photoreceptors activates mGluR6, which is negatively associated with a membrane non-selective cation channel, the transient receptor potential melanoma-related 1, TRPM1, resulting in cell hyperpolarization. The evidence that mGluR6 is expressed not only in the retina but also in other tissues and cell populations has accumulated over time. The expression of mGluR6 has been identified in microglia, bone marrow stromal and prostate cancer cells, B lymphocytes, melanocytes and keratinocytes and non-neural tissues such as testis, kidney, cornea, conjunctiva, and eyelid. The receptor also appears to be expressed in brain areas, such as the hypothalamus, cortex, hippocampus, nucleus of tractus solitarius, superior colliculus, axons of the corpus callosum and accessory olfactory bulb. The pharmacological activation of mGluR6 in the hippocampus produced an anxiolytic-like effect and in the periaqueductal gray analgesic potential. This review aims to collect all the evidence on the expression and functioning of mGluR6 outside the retina that has been accumulated over the years for a broader view of the potential of the receptor whose retinal confinement appears understimated.
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Affiliation(s)
- E Palazzo
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Naples, Italy
| | - S Boccella
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Naples, Italy
| | - I Marabese
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Naples, Italy
| | - G Pierretti
- Department of Plastic Surgery, University of Campania "L. Vanvitelli", Naples, Italy
| | - F Guida
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Naples, Italy
| | - S Maione
- Department of Experimental Medicine, Pharmacology Division, University of Campania "L. Vanvitelli", Naples, Italy
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23
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Stevenson R, Samokhina E, Rossetti I, Morley JW, Buskila Y. Neuromodulation of Glial Function During Neurodegeneration. Front Cell Neurosci 2020; 14:278. [PMID: 32973460 PMCID: PMC7473408 DOI: 10.3389/fncel.2020.00278] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/05/2020] [Indexed: 12/12/2022] Open
Abstract
Glia, a non-excitable cell type once considered merely as the connective tissue between neurons, is nowadays acknowledged for its essential contribution to multiple physiological processes including learning, memory formation, excitability, synaptic plasticity, ion homeostasis, and energy metabolism. Moreover, as glia are key players in the brain immune system and provide structural and nutritional support for neurons, they are intimately involved in multiple neurological disorders. Recent advances have demonstrated that glial cells, specifically microglia and astroglia, are involved in several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Epilepsy, Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal dementia (FTD). While there is compelling evidence for glial modulation of synaptic formation and regulation that affect neuronal signal processing and activity, in this manuscript we will review recent findings on neuronal activity that affect glial function, specifically during neurodegenerative disorders. We will discuss the nature of each glial malfunction, its specificity to each disorder, overall contribution to the disease progression and assess its potential as a future therapeutic target.
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Affiliation(s)
- Rebecca Stevenson
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Evgeniia Samokhina
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Ilaria Rossetti
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - John W. Morley
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- International Centre for Neuromorphic Systems, The MARCS Institute for Brain, Behaviour and Development, Penrith, NSW, Australia
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24
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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: 138] [Impact Index Per Article: 34.5] [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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25
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Abstract
The pervasive and devastating nature of substance use disorders underlies the need for the continued development of novel pharmacotherapies. We now know that glia play a much greater role in neuronal processes than once believed. The various types of glial cells (e.g., astrocytes, microglial, oligodendrocytes) participate in numerous functions that are crucial to healthy central nervous system function. Drugs of abuse have been shown to interact with glia in ways that directly contribute to the pharmacodynamic effects responsible for their abuse potential. Through their effect upon glia, drugs of abuse also alter brain function resulting in behavioral changes associated with substance use disorders. Therefore, drug-induced changes in glia and inflammation within the central nervous system (neuroinflammation) have been investigated to treat various aspects of drug abuse and dependence. This article presents a brief overview of the effects of each of the major classes of addictive drugs on glia. Next, the paper reviews the pre-clinical and clinical studies assessing the effects that glial modulators have on abuse-related behavioral effects, such as pleasure, withdrawal, and motivation. There is a strong body of pre-clinical literature demonstrating the general effectiveness of several glia-modulating drugs in models of reward and relapse. Clinical studies have also yielded promising results, though not as robust. There is still much to disentangle regarding the integration between addictive drugs and glial cells. Improved understanding of the relationship between glia and the pathophysiology of drug abuse should allow for more precise exploration in the development and testing of glial-directed treatments for substance use disorders.
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Affiliation(s)
- Jermaine D. Jones
- Division on Substance Use Disorders, New York State Psychiatric Institute and Columbia University Vagelos College of Physicians and Surgeons, 1051 Riverside Drive, New York, NY 10032, USA
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26
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Abulwerdi G, Stoica BA, Loane DJ, Faden AI. Putative mGluR4 positive allosteric modulators activate G i-independent anti-inflammatory mechanisms in microglia. Neurochem Int 2020; 138:104770. [PMID: 32454165 DOI: 10.1016/j.neuint.2020.104770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/11/2020] [Accepted: 05/15/2020] [Indexed: 01/23/2023]
Abstract
Chronic dysregulated microglial activation may lead to persistent inflammation and progressive neurodegeneration. A previous study reported that ADX88178, a putative metabotropic glutamate receptor 4 (mGluR4) positive allosteric modulator (PAM), exerts anti-inflammatory effects in microglia by activating mGluR4. We employed in vitro models of immortalized microglia cell lines and primary microglia to elucidate the molecular mechanisms responsible for the regulation of inflammatory pathways by ADX88178 and other mGluR4 PAMs. ADX88178 downregulated lipopolysaccharide (LPS)-induced expression of pro-inflammatory mediators, including TNF-α, IL-1β, CCL-2, IL-6, NOS2, and miR-155, as well as NO levels, in BV2 cells and primary microglia. Other mGluR4 modulators had divergent activities; VU0361737 (PAM) showed anti-inflammatory effects, whereas the orthosteric group III agonist, L-AP4, and VU0155041 (PAM) displayed no anti-inflammatory actions. In contrast to the earlier report, ADX88178 anti-inflammatory effects appeared to be mGluR4-independent as mGluR4 expression in our in vitro models was very low and its actions were not altered by pharmacological or molecular inhibition of mGluR4. Moreover, we showed that ADX88178 activated Gi-independent, alternative signaling pathways as indicated by the absence of pertussis toxin-mediated inhibition and by increased phosphorylation of cAMP-response element binding protein (CREB), an inhibitor of the NFkB pro-inflammatory pathway. ADX88178 also attenuated NFkB activation by reducing the degradation of IkB and the associated translocation of NFkB-p65 to the nucleus. ADX88178 did not exert its anti-inflammatory effects through adenosine receptors, reported as mGluR4 heteromerization partners. Thus, our results indicate that in microglia, putative mGluR4 PAMs activate mGluR4/Gi-independent mechanisms to attenuate pro-inflammatory pathways.
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Affiliation(s)
- Gelareh Abulwerdi
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Bogdan A Stoica
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - David J Loane
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Alan I Faden
- Department of Anesthesiology and Shock, Trauma and Anesthesiology Research (STAR) Center, University of Maryland School of Medicine, Baltimore, MD, USA.
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Zhang X, Wang D, Zhang B, Zhu J, Zhou Z, Cui L. Regulation of microglia by glutamate and its signal pathway in neurodegenerative diseases. Drug Discov Today 2020; 25:1074-1085. [PMID: 32320851 DOI: 10.1016/j.drudis.2020.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 03/10/2020] [Accepted: 04/03/2020] [Indexed: 02/06/2023]
Abstract
Microglia are an essential component of the central nervous system (CNS) and are involved in the primary response to microorganisms, neuroinflammation, homeostasis, and tissue regeneration, as well as contributing to the pathogenesis of neurodegenerative diseases. Research has shown that microglial diversity, multifunctionality, and their relationship with glutamate are crucial to determining their roles in these diseases. In this review, we focus on recent progress in determining microglial characteristics and the role of glutamate and its receptors in microglia regulation, which could be a novel therapeutic strategy for neurodegenerative diseases.
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Affiliation(s)
- Xinyue Zhang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China; Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
| | - Dan Wang
- Department of Ophthalmology, the First Hospital of Jilin University, Changchun, China.
| | - Bo Zhang
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden; Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China.
| | - Jie Zhu
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China; Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
| | - Zhulin Zhou
- Department of Neurobiology, Care Sciences & Society, Division of Neurogeriatrics, Karolinska Institutet, Karolinska University Hospital Solna, Stockholm, Sweden.
| | - Li Cui
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China.
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28
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Srivastava A, Das B, Yao AY, Yan R. Metabotropic Glutamate Receptors in Alzheimer's Disease Synaptic Dysfunction: Therapeutic Opportunities and Hope for the Future. J Alzheimers Dis 2020; 78:1345-1361. [PMID: 33325389 PMCID: PMC8439550 DOI: 10.3233/jad-201146] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence of neuritic plaques and neurofibrillary tangles. The impaired synaptic plasticity and dendritic loss at the synaptic level is an early event associated with the AD pathogenesis. The abnormal accumulation of soluble oligomeric amyloid-β (Aβ), the major toxic component in amyloid plaques, is viewed to trigger synaptic dysfunctions through binding to several presynaptic and postsynaptic partners and thus to disrupt synaptic transmission. Over time, the abnormalities in neural transmission will result in cognitive deficits, which are commonly manifested as memory loss in AD patients. Synaptic plasticity is regulated through glutamate transmission, which is mediated by various glutamate receptors. Here we review recent progresses in the study of metabotropic glutamate receptors (mGluRs) in AD cognition. We will discuss the role of mGluRs in synaptic plasticity and their modulation as a possible strategy for AD cognitive improvement.
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Affiliation(s)
- Akriti Srivastava
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Brati Das
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Annie Y. Yao
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
| | - Riqiang Yan
- Department of Neuroscience, University of Connecticut Health, Farmington, CT, USA
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29
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Xiang Y, Han H, Ji S, Wei L, Yang P, Zhang J. The developmental expression of metabotropic glutamate receptor 4 in prenatal human frontal lobe and neurogenesis regions. Brain Dev 2019; 41:567-576. [PMID: 30954358 DOI: 10.1016/j.braindev.2019.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 02/22/2019] [Accepted: 03/25/2019] [Indexed: 01/12/2023]
Abstract
BACKGROUNDS Metabotropic glutamate receptors, besides ionotropic receptors, mediate the complicated effect of glutamate on neurogenesis. Previous studies showed that metabotropic glutamate receptor 4 (mGluR4) regulated the proliferation and differentiation of neural stem/progenitor cells in vitro. However, little is known about the expression pattern of mGluR4 on prenatal central nervous system in vivo, especially the human being. METHODS The normal brain tissues of human fetus were collected and divided into 4 groups according to the gestational age: 9-11 W, 14-16 W, 22-24 W and 32-36 W. Then the expression of mGluR4 was evaluated at mRNA and protein levels by means of PCR or immunohistochemistry method, respectively. The type of cell expressing mGluR4 was further investigated using double-labeling immunofluorescence. RESULTS RT-PCR showed that the mRNA of mGluR4 could be detected in frontal lobe from 9 W to 32 W and real-time PCR quantificationally demonstrated the mRNA increased with development. Similarly, immnoreactivity was found in all layers of frontal lobe, VZ/SVZ. The intensity scores analysis showed that the staining became stronger and the range extended gradually with development. The double-labeling immunofluorescence showed that mGluR4 was present in neural stem/progenitor cells (nestin-positive cells after 9 W), young neurons (DCX-positive cells after 9 W), mature neurons (NeuN-positive cells in cortex after 32 W), as well as typical astrocytes (GFAP-positive cells in medulla after 32 W). CONCLUSION These results supply an important evidence that mGluR4 is expressed in prenatal human cerebrum, and main kinds of cells related to neurogenesis are involved in its expression.
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Affiliation(s)
- Yan Xiang
- Department of Internal Medicine, Xi'an Huashan Central Hospital, China
| | - Hua Han
- Department of Human Anatomy, Histology and Embryology, Xi'an Jiaotong University Health Science Center, China
| | - Shengfeng Ji
- Department of Human Anatomy, Histology and Embryology, Xi'an Jiaotong University Health Science Center, China
| | - Liang Wei
- Department of Human Anatomy & Shaanxi Key Laboratory of Brain Disorders, Xi'an Medical University, China
| | - Pengbo Yang
- Department of Human Anatomy, Histology and Embryology, Xi'an Jiaotong University Health Science Center, China.
| | - Junfeng Zhang
- Department of Human Anatomy & Shaanxi Key Laboratory of Brain Disorders, Xi'an Medical University, China.
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30
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Pereira V, Goudet C. Emerging Trends in Pain Modulation by Metabotropic Glutamate Receptors. Front Mol Neurosci 2019; 11:464. [PMID: 30662395 PMCID: PMC6328474 DOI: 10.3389/fnmol.2018.00464] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/30/2018] [Indexed: 12/20/2022] Open
Abstract
Pain is an essential protective mechanism meant to prevent tissue damages in organisms. On the other hand, chronic or persistent pain caused, for example, by inflammation or nerve injury is long lasting and responsible for long-term disability in patients. Therefore, chronic pain and its management represents a major public health problem. Hence, it is critical to better understand chronic pain molecular mechanisms to develop innovative and efficient drugs. Over the past decades, accumulating evidence has demonstrated a pivotal role of glutamate in pain sensation and transmission, supporting glutamate receptors as promising potential targets for pain relieving drug development. Glutamate is the most abundant excitatory neurotransmitter in the brain. Once released into the synapse, glutamate acts through ionotropic glutamate receptors (iGluRs), which are ligand-gated ion channels triggering fast excitatory neurotransmission, and metabotropic glutamate receptors (mGluRs), which are G protein-coupled receptors modulating synaptic transmission. Eight mGluRs subtypes have been identified and are divided into three classes based on their sequence similarities and their pharmacological and biochemical properties. Of note, all mGluR subtypes (except mGlu6 receptor) are expressed within the nociceptive pathways where they modulate pain transmission. This review will address the role of mGluRs in acute and persistent pain processing and emerging pharmacotherapies for pain management.
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Affiliation(s)
- Vanessa Pereira
- IGF, CNRS, INSERM, Univ. de Montpellier, Montpellier, France
| | - Cyril Goudet
- IGF, CNRS, INSERM, Univ. de Montpellier, Montpellier, France
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31
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Abstract
Microglial cells derive from fetal macrophages which immigrate into and disseminate throughout the central nervous system (CNS) in early embryogenesis. After settling in the nerve tissue, microglial progenitors acquire an idiosyncratic morphological phenotype with small cell body and moving thin and highly ramified processes currently defined as "resting or surveillant microglia". Physiology of microglia is manifested by second messenger-mediated cellular excitability, low resting membrane conductance, and expression of receptors to pathogen- or damage-associated molecular patterns (PAMPs and DAMPs), as well as receptors to classical neurotransmitters and neurohormones. This specific physiological profile reflects adaptive changes of myeloid cells to the CNS environment.
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Affiliation(s)
- Olga Garaschuk
- Department of Neurophysiology, Institute of Physiology, Eberhard Karls University of Tübingen, Tübingen, Germany.
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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32
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An introduction to innate immunity in the central nervous system. ROLE OF INFLAMMATION IN ENVIRONMENTAL NEUROTOXICITY 2019. [DOI: 10.1016/bs.ant.2018.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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33
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Younger D, Murugan M, Rama Rao KV, Wu LJ, Chandra N. Microglia Receptors in Animal Models of Traumatic Brain Injury. Mol Neurobiol 2018; 56:5202-5228. [DOI: 10.1007/s12035-018-1428-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/13/2018] [Indexed: 02/07/2023]
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34
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Spampinato SF, Copani A, Nicoletti F, Sortino MA, Caraci F. Metabotropic Glutamate Receptors in Glial Cells: A New Potential Target for Neuroprotection? Front Mol Neurosci 2018; 11:414. [PMID: 30483053 PMCID: PMC6243036 DOI: 10.3389/fnmol.2018.00414] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 10/25/2018] [Indexed: 12/14/2022] Open
Abstract
Neurodegenerative disorders are characterized by excitotoxicity and neuroinflammation that finally lead to slow neuronal degeneration and death. Although neurons are the principal target, glial cells are important players as they contribute by either exacerbating or dampening the events that lead to neuroinflammation and neuronal damage. A dysfunction of the glutamatergic system is a common event in the pathophysiology of these diseases. Metabotropic glutamate (mGlu) receptors belong to a large family of G protein-coupled receptors largely expressed in neurons as well as in glial cells. They often appear overexpressed in areas involved in neurodegeneration, where they can modulate glutamatergic transmission. Of note, mGlu receptor upregulation may involve microglia or, even more frequently, astrocytes, where their activation causes release of factors potentially able to influence neuronal death. The expression of mGlu receptors has been also reported on oligodendrocytes, a glial cell type specifically involved in the development of multiple sclerosis. Here we will provide a general overview on the possible involvement of mGlu receptors expressed on glial cells in the pathogenesis of different neurodegenerative disorders and the potential use of subtype-selective mGlu receptor ligands as candidate drugs for the treatment of neurodegenerative disorders. Negative allosteric modulators (NAM) of mGlu5 receptors might represent a relevant pharmacological tool to develop new neuroprotective strategies in these diseases. Recent evidence suggests that targeting astrocytes and microglia with positive allosteric modulators (PAM) of mGlu3 receptor or oligodendrocytes with mGlu4 PAMS might represent novel pharmacological approaches for the treatment of neurodegenerative disorders.
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Affiliation(s)
| | - Agata Copani
- Department of Drug Sciences, University of Catania, Catania, Italy.,Institute of Biostructure and Bioimaging, National Research Council, Catania, Italy
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,Neuromed, Istituto di Ricovero e Cura a Carattere Scientifico, Pozzilli, Italy
| | - Maria Angela Sortino
- Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Caraci
- Department of Drug Sciences, University of Catania, Catania, Italy.,Oasi Research Institute, Istituto di Ricovero e Cura a Carattere Scientifico, Troina, Italy
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35
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Cohen EM, Farnham MMJ, Kakall Z, Kim SJ, Nedoboy PE, Pilowsky PM. Glia and central cardiorespiratory pathology. Auton Neurosci 2018; 214:24-34. [PMID: 30172674 DOI: 10.1016/j.autneu.2018.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/22/2018] [Accepted: 08/22/2018] [Indexed: 01/08/2023]
Abstract
Respiration and blood pressure are primarily controlled by somatic and autonomic motor neurones, respectively. Central cardiorespiratory control is critical in moment-to-moment survival, but it also has a role in the development and maintenance of chronic pathological conditions such as hypertension. The glial cells of the brain are non-neuronal cells with metabolic, immune, and developmental functions. Recent evidence shows that glia play an active role in supporting and regulating the neuronal circuitry which drives the cardiorespiratory system. Here we will review the activities of two key types of glial cell, microglia and astrocytes, in assisting normal central cardiorespiratory control and in pathology.
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Affiliation(s)
- E Myfanwy Cohen
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Melissa M J Farnham
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Zohra Kakall
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Seung Jae Kim
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Polina E Nedoboy
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Paul M Pilowsky
- The Heart Research Institute, Sydney, New South Wales 2042, Australia; Sydney Medical School, University of Sydney, Sydney, New South Wales 2006, Australia.
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36
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Haque ME, Kim IS, Jakaria M, Akther M, Choi DK. Importance of GPCR-Mediated Microglial Activation in Alzheimer's Disease. Front Cell Neurosci 2018; 12:258. [PMID: 30186116 PMCID: PMC6110855 DOI: 10.3389/fncel.2018.00258] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/30/2018] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder associated with impairment of cognition, memory deficits and behavioral abnormalities. Accumulation of amyloid beta (Aβ) is a characteristic hallmark of AD. Microglia express several GPCRs, which, upon activation by modulators, mediate microglial activation and polarization phenotype. This GPCR-mediated microglial activation has both protective and detrimental effects. Microglial GPCRs are involved in amyloid precursor protein (APP) cleavage and Aβ generation. In addition, microglial GPCRs are featured in the regulation of Aβ degradation and clearance through microglial phagocytosis and chemotaxis. Moreover, in response to Aβ binding on microglial Aβ receptors, they can trigger multiple inflammatory pathways. However, there is still a lack of insight into the mechanistic link between GPCR-mediated microglial activation and its pathological consequences in AD. Currently, the available drugs for the treatment of AD are mostly symptomatic and dominated by acetylcholinesterase inhibitors (AchEI). The selection of a specific microglial GPCR that is highly expressed in the AD brain and capable of modulating AD progression through Aβ generation, degradation and clearance will be a potential source of therapeutic intervention. Here, we have highlighted the expression and distribution of various GPCRs connected to microglial activation in the AD brain and their potential to serve as therapeutic targets of AD.
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Affiliation(s)
- Md Ezazul Haque
- Department of Applied Life Science, Graduate School, Konkuk University, Chungju, South Korea
| | - In-Su Kim
- Department of Integrated Bioscience and Biotechnology, College of Biomedical and Health Science, Research Institute of Inflammatory Disease, Konkuk University, Chungju, South Korea
| | - Md Jakaria
- Department of Applied Life Science, Graduate School, Konkuk University, Chungju, South Korea
| | - Mahbuba Akther
- Department of Applied Life Science, Graduate School, Konkuk University, Chungju, South Korea
| | - Dong-Kug Choi
- Department of Applied Life Science, Graduate School, Konkuk University, Chungju, South Korea.,Department of Integrated Bioscience and Biotechnology, College of Biomedical and Health Science, Research Institute of Inflammatory Disease, Konkuk University, Chungju, South Korea
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37
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Abstract
Microglia differentiate from progenitors that infiltrate the nascent CNS during early embryonic development. They then remain in this unique immune-privileged environment throughout life. Multiple immune mechanisms, which we collectively refer to as microglial checkpoints, ensure efficient and tightly regulated microglial responses to perturbations in the CNS milieu. Such mechanisms are essential for proper CNS development and optimal physiological function. However, in chronic disease or aging, when a robust immune response is required, such checkpoint mechanisms may limit the ability of microglia to protect the CNS. Here we survey microglial checkpoint mechanisms and their roles in controlling microglial function throughout life and in disease, and discuss how they may be targeted therapeutically.
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38
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Masilamoni GJ, Smith Y. Metabotropic glutamate receptors: targets for neuroprotective therapies in Parkinson disease. Curr Opin Pharmacol 2018; 38:72-80. [PMID: 29605730 DOI: 10.1016/j.coph.2018.03.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 03/12/2018] [Indexed: 01/22/2023]
Abstract
Metabotropic glutamate receptors (mGluRs) are heavily expressed throughout the basal ganglia (BG), where they modulate neuronal excitability, transmitter release and long term synaptic plasticity. Therefore, targeting specific mGluR subtypes by means of selective drugs could be a possible strategy for restoring normal synaptic function and neuronal activity of the BG in Parkinson disease (PD). Preclinical studies have revealed that specific mGluR subtypes mediate significant neuroprotective effects that reduce toxin-induced midbrain dopaminergic neuronal death in animal models of PD. Although the underlying mechanisms of these effects must be further studied, there is evidence that intracellular calcium regulation, anti-inflammatory effects, and glutamatergic network modulation contribute to some of these neuroprotective properties. It is noteworthy that these protective effects extend beyond midbrain dopaminergic neurons to include other monoaminergic cell groups for some mGluRs. In this review, we discuss evidence for mGluR-mediated neuroprotection in PD and highlight the challenges to translate these findings into human trials.
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Affiliation(s)
- Gunasingh J Masilamoni
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Udall Center of Excellence for Parkinson's Disease, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Department of Neurology, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA; Udall Center of Excellence for Parkinson's Disease, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30322, USA.
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39
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mGlu 4 allosteric modulation for treating Parkinson's disease. Neuropharmacology 2018; 135:308-315. [PMID: 29578036 DOI: 10.1016/j.neuropharm.2018.03.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/20/2018] [Accepted: 03/21/2018] [Indexed: 12/21/2022]
Abstract
2017 is the 200th anniversary of the first published description of Parkinson's disease (PD). Fifty years ago, the clinical benefit of levodopa was first documented, representing the most important advance in the treatment of PD so far. Among the novel targets identified in the last decade, positive allosteric modulators (PAM) of mGlu4 receptors show great promise, with the potential to change the paradigm of the PD treatment approach. mGlu4 PAMs have shown consistent efficacy in various preclinical models of PD, and entered clinical trials for the first time in 2017. This review synthesizes the rationale for mGlu4 PAM development for PD and progress to date, reporting the key achievements from preclinical studies to the first-in-class compound assessment in man.
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40
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Fazio F, Ulivieri M, Volpi C, Gargaro M, Fallarino F. Targeting metabotropic glutamate receptors for the treatment of neuroinflammation. Curr Opin Pharmacol 2018; 38:16-23. [PMID: 29471184 DOI: 10.1016/j.coph.2018.01.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 01/31/2018] [Indexed: 12/15/2022]
Abstract
A large body of evidence suggests that neuroinflammation lies at the core of nearly all CNS disorders, including psychiatric disorders. Invading and local immune cells orchestrate the series of events that lead to either tissue repair or damage in response to neuroinflammation. Both lymphocytes and microglia express metabotropic glutamate (mGlu) receptors, which respond to glutamate or other endogenous activators (e.g. some kynurenine metabolites of tryptophan metabolism) influencing immune phenotype and the balance between pro-inflammatory and anti-inflammatory cytokines. Here, we offer an up-to-date on the role of individual mGlu receptor subtypes in the regulation of innate and adaptive immune response, highlighting the relevance of this information in the development of subtype-selective mGlu receptor ligands for treatment of CNS disorders.
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Affiliation(s)
| | - Martina Ulivieri
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
| | - Claudia Volpi
- Department of Experimental Medicine, University of Perugia, Polo Unico Sant'Andrea delle Fratte, Piazzale Gambuli, 06132 Perugia, Italy
| | - Marco Gargaro
- Department of Experimental Medicine, University of Perugia, Polo Unico Sant'Andrea delle Fratte, Piazzale Gambuli, 06132 Perugia, Italy
| | - Francesca Fallarino
- Department of Experimental Medicine, University of Perugia, Polo Unico Sant'Andrea delle Fratte, Piazzale Gambuli, 06132 Perugia, Italy
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41
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York EM, Bernier LP, MacVicar BA. Microglial modulation of neuronal activity in the healthy brain. Dev Neurobiol 2017; 78:593-603. [PMID: 29271125 DOI: 10.1002/dneu.22571] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/19/2017] [Accepted: 12/19/2017] [Indexed: 01/06/2023]
Abstract
Investigations on the role of microglia in the brain have traditionally been focused on their contributions to disease states. However, recent observations have now convincingly shown that microglia in the healthy brain are not passive bystanders, but instead play a critical role in both central nervous system development and homeostasis of synaptic circuits in the adult. Here, we review the various mechanisms by which microglia impact neuronal communication in the healthy adult brain, both by sensing nearby synaptic responses and by actively modulating neuronal function. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 593-603, 2018.
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Affiliation(s)
- Elisa M York
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Louis-Philippe Bernier
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Brian A MacVicar
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
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42
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Let's make microglia great again in neurodegenerative disorders. J Neural Transm (Vienna) 2017; 125:751-770. [PMID: 29027011 DOI: 10.1007/s00702-017-1792-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 09/18/2017] [Indexed: 12/12/2022]
Abstract
All of the common neurodegenerative disorders-Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and prion diseases-are characterized by accumulation of misfolded proteins that trigger activation of microglia; brain-resident mononuclear phagocytes. This chronic form of neuroinflammation is earmarked by increased release of myriad cytokines and chemokines in patient brains and biofluids. Microglial phagocytosis is compromised early in the disease process, obfuscating clearance of abnormal proteins. This review identifies immune pathologies shared by the major neurodegenerative disorders. The overarching concept is that aberrant innate immune pathways can be targeted for return to homeostasis in hopes of coaxing microglia into clearing neurotoxic misfolded proteins.
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Metabotropic glutamate receptors and neurodegenerative diseases. Pharmacol Res 2017; 115:179-191. [DOI: 10.1016/j.phrs.2016.11.013] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/11/2016] [Accepted: 11/15/2016] [Indexed: 12/21/2022]
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Carta AR, Mulas G, Bortolanza M, Duarte T, Pillai E, Fisone G, Vozari RR, Del-Bel E. l-DOPA-induced dyskinesia and neuroinflammation: do microglia and astrocytes play a role? Eur J Neurosci 2016; 45:73-91. [DOI: 10.1111/ejn.13482] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 11/07/2016] [Accepted: 11/11/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Anna R. Carta
- Department of Biomedical Sciences; University of Cagliari, Cittadella Universitaria di Monserrato; S.P. N. 8 09042 Monserrato Cagliari Italy
| | - Giovanna Mulas
- Department of Biomedical Sciences; University of Cagliari, Cittadella Universitaria di Monserrato; S.P. N. 8 09042 Monserrato Cagliari Italy
| | - Mariza Bortolanza
- School of Odontology of Ribeirão Preto; Department of Morphology, Physiology and Basic Pathology; University of São Paulo (USP); Av. Café S/N 14040-904 Ribeirão Preto SP Brazil
- USP, Center for Interdisciplinary Research on Applied Neurosciences (NAPNA); São Paulo Brazil
| | - Terence Duarte
- School of Odontology of Ribeirão Preto; Department of Morphology, Physiology and Basic Pathology; University of São Paulo (USP); Av. Café S/N 14040-904 Ribeirão Preto SP Brazil
- USP, Center for Interdisciplinary Research on Applied Neurosciences (NAPNA); São Paulo Brazil
| | - Elisabetta Pillai
- Department of Biomedical Sciences; University of Cagliari, Cittadella Universitaria di Monserrato; S.P. N. 8 09042 Monserrato Cagliari Italy
| | - Gilberto Fisone
- Department of Neuroscience; Karolinska Institutet; Retzius väg 8 17177 Stockholm Sweden
| | - Rita Raisman Vozari
- INSERM U 1127; CNRS UMR 7225; UPMC Univ Paris 06; UMR S 1127; Institut Du Cerveau et de La Moelle Epiniére; ICM; Paris France
| | - Elaine Del-Bel
- School of Odontology of Ribeirão Preto; Department of Morphology, Physiology and Basic Pathology; University of São Paulo (USP); Av. Café S/N 14040-904 Ribeirão Preto SP Brazil
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Clemons TD, Challenor M, Fitzgerald M, Dunlop SA, Smith NM, Iyer KS. Manipulating Cellular Interactions of Poly(glycidyl methacrylate) Nanoparticles Using Mixed Polymer Brushes. ACS Macro Lett 2016; 5:1132-1136. [PMID: 35658171 DOI: 10.1021/acsmacrolett.6b00613] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There is a growing need for the development of nanoparticles, with imaging and drug delivery capabilities, to maintain cellular uptake but avoid protein attachment and recognition. In this study we have demonstrated that nanoparticles consisting of a poly(glycidyl methacrylate) (PGMA) core and a mixed brush architecture of methoxypoly(ethylene glycol) and poly(ethylenimine) (mPEG-PEI) on the surface can meet this need. Surface functionalization with PEI alone results in cellular uptake, but rapid protein attachment whereas PEG alone can avoid protein attachment but to the detriment of cellular uptake. A mixed copolymer brush of both PEI and mPEG provides the ideal balance.
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Affiliation(s)
- Tristan D. Clemons
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Michael Challenor
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Melinda Fitzgerald
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Sarah A. Dunlop
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Nicole M. Smith
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - K. Swaminathan Iyer
- School of Chemistry and Biochemistry and ‡Experimental and Regenerative Neurosciences,
School of Animal Biology, The University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
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The neuroprotective effects of orthosteric agonists of group II and III mGluRs in primary neuronal cell cultures are dependent on developmental stage. Neuropharmacology 2016; 111:195-211. [PMID: 27600687 DOI: 10.1016/j.neuropharm.2016.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/12/2016] [Accepted: 09/02/2016] [Indexed: 11/22/2022]
Abstract
Activation of metabotropic glutamate receptors (mGluRs) modulates neuronal excitability. Here, we evaluated the neuroprotective potential of four structurally diverse activators of group II and III mGluRs: an orthosteric agonist of group II (LY354740), an orthosteric agonist of group III (ACPT-I), an allosteric agonist of mGluR7 (AMN082) and a positive allosteric modulator (PAM) of mGluR4 (VU0361737). Neurotoxicity was induced by the pro-apoptotic agents: staurosporine (St) and doxorubicin (Dox) or the excitotoxic factor glutamate (Glu). The effects were analyzed in primary hippocampal (HIP) and cerebellar granule cell (CGC) cultures at two developmental stages, at 7 and 12 days in vitro (DIV). The data reveal a general neuroprotective effect of group II and III mGluR activators against the St- and Glu- but not Dox-induced cell damage. We found that neuroprotective effects of group II and III mGluR orthosteric agonists (LY354740 and ACPT-I) were higher at 12 DIV when compared to 7 DIV cells. In contrast, the efficiency of allosteric mGluR agents (AMN082 and VU0361737) did not differ between 7 and 12 DIV in both, St and Glu models of neuronal cell damage. Interestingly, the protective effects of activators of group II and III mGluRs were blocked by relevant antagonists only against Glu-induced neurotoxicity. Moreover, the observed neuroprotective action of group II and III mGluR activators in the St model was associated with a decreased number of PI-positive cells and no alterations in the caspase-3 activity. Finally, we showed that MAPK/ERK pathway activation was potentially involved in the mechanism of ACPT-I- and AMN082-induced neuroprotection against the St-evoked cellular damage. Our comparative study demonstrated the developmental stage-dependent neuroprotective effect of orthosteric group II and III mGluR agonists. In comparison to allosteric modulators, orthosteric compounds may provide more specific tools for suppression of neuronal cell loss associated with various chronic neurodegenerative conditions. Our results also suggest that the inhibition of intracellular pathways mediating necrotic, rather than apoptotic cascades, may be involved in neuroprotective effects of activators of group II and III mGluRs.
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Liu H, Leak RK, Hu X. Neurotransmitter receptors on microglia. Stroke Vasc Neurol 2016; 1:52-58. [PMID: 28959464 PMCID: PMC5435193 DOI: 10.1136/svn-2016-000012] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 04/29/2016] [Accepted: 04/30/2016] [Indexed: 12/21/2022] Open
Abstract
As the resident immune cells in the central nervous system, microglia have long been hypothesised to promote neuroinflammation and exacerbate neurotoxicity. However, this traditional view has undergone recent revision as evidence has accumulated that microglia exert beneficial and detrimental effects depending on activation status, polarisation phenotype and cellular context. A variety of neurotransmitter receptors are expressed on microglia and help mediate the bidirectional communication between neurons and microglia. Here we review data supporting the importance of neurotransmitter receptors on microglia, with a special emphasis on glutamate, γ-aminobutyric acid (GABA), norepinephrine, cannabinoid and acetylcholine receptors. We summarise evidence favouring a significant role for neurotransmitter receptors in modulating microglial activation, phagocytic clearance and phenotypic polarisation. Elucidating the effects of neurotransmitter receptors on microglia and dissecting the underlying mechanisms may help accelerate the discovery of novel drugs that tap the therapeutic potential of microglia.
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Affiliation(s)
- Huan Liu
- Center of Cerebrovascular Disease Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Xiaoming Hu
- Center of Cerebrovascular Disease Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Ponnazhagan R, Harms AS, Thome AD, Jurkuvenaite A, Gogliotti R, Niswender CM, Conn PJ, Standaert DG. The Metabotropic Glutamate Receptor 4 Positive Allosteric Modulator ADX88178 Inhibits Inflammatory Responses in Primary Microglia. J Neuroimmune Pharmacol 2016; 11:231-7. [PMID: 26872456 PMCID: PMC4848139 DOI: 10.1007/s11481-016-9655-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 02/03/2016] [Indexed: 11/27/2022]
Abstract
While the specific trigger of Parkinson Disease (PD) in most patients is unknown, considerable evidence suggests that the neuroinflammatory response makes an essential contribution to the neurodegenerative process. Drugs targeting metabotropic glutamate receptors (mGlu receptors), 7 Transmembrane (7TM) spanning/G protein coupled receptors that bind glutamate, are emerging as therapeutic targets for PD and may have anti-inflammatory properties. ADX88178 is novel potent, selective, and brain-penetrant positive allosteric modulator of the mGlu4 which is under evaluation for treatment of PD and other neurological disorders. We used microglia cultured from mouse brain to determine if ADX88178 had direct effects on the inflammatory responses of these cells. We studied both microglia from wild type and Grm4 knock out mice. We found that activation of mGlu4 with ADX88178 attenuated LPS-induced inflammation in primary microglia, leading to a decrease in the expression of TNFα, MHCII, and iNOS, markers of pro-inflammatory responses. These effects were absent in microglia from mice lacking mGlu4. These results demonstrate a cell-autonomous anti-inflammatory effect of ADX88178 mediated mGlu4 activation on microglia, and suggest that this drug or similar activators or potentiators of mGlu4 may have disease-modifying as well as symptomatic effects in PD and other brain disorders with an inflammatory component.
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Affiliation(s)
- Ranjani Ponnazhagan
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Ashley S Harms
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Aaron D Thome
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Asta Jurkuvenaite
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Rocco Gogliotti
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt Kennedy Center, Vanderbilt University, Nashville, TN, 37235, USA
| | - Colleen M Niswender
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt Kennedy Center, Vanderbilt University, Nashville, TN, 37235, USA
| | - P Jeffrey Conn
- Vanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt Kennedy Center, Vanderbilt University, Nashville, TN, 37235, USA
| | - David G Standaert
- Center for Neurodegeneration and Experimental Therapeutics, Department of Neurology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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Alerted microglia and the sympathetic nervous system: A novel form of microglia in the development of hypertension. Respir Physiol Neurobiol 2016; 226:51-62. [DOI: 10.1016/j.resp.2015.11.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/24/2015] [Accepted: 11/25/2015] [Indexed: 02/07/2023]
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TLR4-activated microglia require IFN-γ to induce severe neuronal dysfunction and death in situ. Proc Natl Acad Sci U S A 2015; 113:212-7. [PMID: 26699475 DOI: 10.1073/pnas.1513853113] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Microglia (tissue-resident macrophages) represent the main cell type of the innate immune system in the CNS; however, the mechanisms that control the activation of microglia are widely unknown. We systematically explored microglial activation and functional microglia-neuron interactions in organotypic hippocampal slice cultures, i.e., postnatal cortical tissue that lacks adaptive immunity. We applied electrophysiological recordings of local field potential and extracellular K(+) concentration, immunohistochemistry, design-based stereology, morphometry, Sholl analysis, and biochemical analyses. We show that chronic activation with either bacterial lipopolysaccharide through Toll-like receptor 4 (TLR4) or leukocyte cytokine IFN-γ induces reactive phenotypes in microglia associated with morphological changes, population expansion, CD11b and CD68 up-regulation, and proinflammatory cytokine (IL-1β, TNF-α, IL-6) and nitric oxide (NO) release. Notably, these reactive phenotypes only moderately alter intrinsic neuronal excitability and gamma oscillations (30-100 Hz), which emerge from precise synaptic communication of glutamatergic pyramidal cells and fast-spiking, parvalbumin-positive GABAergic interneurons, in local hippocampal networks. Short-term synaptic plasticity and extracellular potassium homeostasis during neural excitation, also reflecting astrocyte function, are unaffected. In contrast, the coactivation of TLR4 and IFN-γ receptors results in neuronal dysfunction and death, caused mainly by enhanced microglial inducible nitric oxide synthase (iNOS) expression and NO release, because iNOS inhibition is neuroprotective. Thus, activation of TLR4 in microglia in situ requires concomitant IFN-γ receptor signaling from peripheral immune cells, such as T helper type 1 and natural killer cells, to unleash neurotoxicity and inflammation-induced neurodegeneration. Our findings provide crucial mechanistic insight into the complex process of microglia activation, with relevance to several neurologic and psychiatric disorders.
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