51
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Therapeutic potential of extracellular ATP and P2 receptors in nervous system diseases. Neurosci Bull 2009; 25:27-32. [PMID: 19190686 DOI: 10.1007/s12264-009-1020-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Extracellular adenosine 5 inch-triphosphate (ATP) is a key signaling molecule present in the central nervous system (CNS), and now is receiving greater attention due to its role as a messenger in the CNS during different physiological and pathological events. ATP is released into the extracellular space through vesicular exocytosis or from damaged and dying cells. Once in the extracellular environment, ATP binds to the specific receptors termed P2, which mediate ATP effects and are present broadly in both neurons and glial cells. There are P2X, the ligand-gated ionotropic receptors, possessing low affinity for ATP and responsible for fast excitatory neurotransmission, and P2Y, the metabotropic G-protein-coupled receptors, possessing high affinity for ATP. Since massive extracellular release of ATP often occurs after stress, brain ischemia and trauma, the extracellular ATP is considered relating to or involving in the pathological processes of many nervous system diseases. Conversely, the trophic functions have also been extensively described for the extracellular ATP. Therefore, extracellular ATP plays a very complex role in the CNS and its binding to P2 receptors can be related to toxic and/or beneficial effects. In this review, we described the extracellular ATP acting via P2 receptors as a potent therapeutic target for treatment of nervous system diseases.
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52
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Cotrina ML, Nedergaard M. Physiological and pathological functions of P2X7 receptor in the spinal cord. Purinergic Signal 2009; 5:223-32. [PMID: 19205927 DOI: 10.1007/s11302-009-9138-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 07/15/2008] [Indexed: 12/24/2022] Open
Abstract
ATP-mediated signaling has widespread actions in the nervous system from neurotransmission to regulation of proliferation. In addition, ATP is released during injury and associated to immune and inflammatory responses. Still, the potential of therapeutic intervention of purinergic signaling during pathological states is only now beginning to be explored because of the large number of purinergic receptors subtypes involved, the complex and often overlapping pharmacology and because ATP has effects on every major cell type present in the CNS. In this review, we will focus on a subclass of purinergic-ligand-gated ion channels, the P2X7 receptor, its pattern of expression and its function in the spinal cord where it is abundantly expressed. We will discuss the mechanisms for P2X7R actions and the potential that manipulating the P2X7R signaling pathway may have for therapeutic intervention in pathological events, specifically in the spinal cord.
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Affiliation(s)
- Maria Luisa Cotrina
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, 14642, USA,
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53
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Matute C. P2X7 receptors in oligodendrocytes: a novel target for neuroprotection. Mol Neurobiol 2008; 38:123-8. [PMID: 18704769 DOI: 10.1007/s12035-008-8028-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 05/13/2008] [Indexed: 10/21/2022]
Abstract
Intense ATP signaling through P2X7 purinergic receptors can lead to excitotoxicity, a feature which initiates neuronal demise in experimental paradigms relevant to ischemia and to traumatic injury. In addition, recent data provide evidence that oligodendrocytes also express P2X7 receptors that are activated under experimental pathological conditions involving white matter demise. Thus, this receptor subtype is a promising target for the development of new drugs to prevent white matter damage in acute and chronic diseases.
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Affiliation(s)
- Carlos Matute
- CIBERNED, Departamento de Neurociencias, Universidad del País Vasco, 48940-Leioa, and Neurotek-UPV/EHU, Parque Tecnológico de Bizkaia, 48170 Zamudio, Spain.
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54
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Burnstock G. Purinergic signalling and disorders of the central nervous system. Nat Rev Drug Discov 2008; 7:575-90. [PMID: 18591979 DOI: 10.1038/nrd2605] [Citation(s) in RCA: 446] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Purines have key roles in neurotransmission and neuromodulation, with their effects being mediated by the purine and pyrimidine receptor subfamilies, P1, P2X and P2Y. Recently, purinergic mechanisms and specific receptor subtypes have been shown to be involved in various pathological conditions including brain trauma and ischaemia, neurodegenerative diseases involving neuroimmune and neuroinflammatory reactions, as well as in neuropsychiatric diseases, including depression and schizophrenia. This article reviews the role of purinergic signalling in CNS disorders, highlighting specific purinergic receptor subtypes, most notably A(2A), P2X(4) and P2X(7), that might be therapeutically targeted for the treatment of these conditions.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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55
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Yanagisawa D, Kitamura Y, Takata K, Hide I, Nakata Y, Taniguchi T. Possible involvement of P2X7 receptor activation in microglial neuroprotection against focal cerebral ischemia in rats. Biol Pharm Bull 2008; 31:1121-30. [PMID: 18520042 DOI: 10.1248/bpb.31.1121] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Microglia play important roles in the pathogenic cascade following cerebral ischemia, since they express growth factors, chemokines and regulatory cytokines as well as free radicals and other toxic mediators. P2X7 receptor, a subtype of a family of P2 purinoceptors, is primarily expressed in microglia and macrophages, suggesting that it regulates immune function and inflammatory responses. However, the involvement of ATP in such microglial responses after cerebral ischemia is not yet understood. In this study, we investigated the possible involvement of ATP, especially through the P2X7 receptors, in a rat model of focal cerebral ischemia. In immunohistochemical analysis, P2X7 receptor-like immunoreactivity was predominantly detected in microglia, and then activated microglia accumulated in the ischemic region, in rats subjected to middle cerebral artery occlusion (MCAO) and reperfusion. Intracerebroventricular injection with P2X7 receptor agonist 2'-3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) improved behavioral dysfunction accessed by rota-rod test and ischemic neural injury induced by MCAO. In contrast, P2X7 receptor antagonist adenosine 5'-triphosphate-2',3'-dialdehyde (OxATP) exacerbated ischemic brain damage. These results suggest that microglia play an important role in neuroprotection against rat cerebral ischemia, which is regulated by a P2X7 receptor-mediated ATP signal.
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Affiliation(s)
- Daijiro Yanagisawa
- Department of Neurobiology, 21st Century COE Program, Kyoto Pharmaceutical University, Misasagi, Kyoto, Japan
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56
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Acute neurodegeneration and the inflammasome: central processor for danger signals and the inflammatory response? J Cereb Blood Flow Metab 2008; 28:867-81. [PMID: 18212795 DOI: 10.1038/sj.jcbfm.9600609] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Activation of the inflammatory response is a crucial event in the adverse outcome of cerebral ischemia, which is promoted by proinflammatory cytokines such as interleukin (IL)-1beta. Although caspase-1 is necessary for IL-1beta processing, the 'upstream' signaling pathways were, until recently, essentially unknown. Fortunately, the inflammasome, a multiprotein complex responsible for activating caspase-1 and caspase-5, has recently been characterized. The activation of the inflammasome can result in one of several consequences such as cytokine secretion, cell death, or the development of a stress-resistant state. The significance of the inflammasome for the initiation of the inflammatory response during systemic diseases has already been shown and members of the inflammasome complex were recently found to be induced in acute brain injury. However, the specific pathophysiologic role of the inflammasome in neurodegenerative disorders still remains to be clarified. The underlying theories (e.g., danger signal theory) along with the signaling pathways that link the inflammasome to acute neurodegeneration will be discussed here. Furthermore, the stimuli that potentially activate the inflammasome in cerebral ischemia will be specified, as well as their relation to well-known pathways activating the innate immune response (e.g., Toll-like receptor signaling) and the consequences that result from their activation (beneficial versus deleterious).
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57
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Nelson DW, Sarris K, Kalvin DM, Namovic MT, Grayson G, Donnelly-Roberts DL, Harris R, Honore P, Jarvis MF, Faltynek CR, Carroll WA. Structure−Activity Relationship Studies on N′-Aryl Carbohydrazide P2X7 Antagonists. J Med Chem 2008; 51:3030-4. [DOI: 10.1021/jm701516f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Derek W. Nelson
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Kathy Sarris
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Douglas M. Kalvin
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Marian T. Namovic
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - George Grayson
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Diana L. Donnelly-Roberts
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Richard Harris
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Prisca Honore
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Michael F. Jarvis
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - Connie R. Faltynek
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
| | - William A. Carroll
- Abbott Laboratories, Neuroscience Research and Advanced Technology, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101
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58
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Skaper SD. The brain as a target for inflammatory processes and neuroprotective strategies. Ann N Y Acad Sci 2008; 1122:23-34. [PMID: 18077562 DOI: 10.1196/annals.1403.002] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The importance of glial cell-propagated inflammation (i.e., neuroinflammation) disorders such as Alzheimer's disease (AD) was viewed previously as a bystander effect, or epiphenomenon, with inflammation occurring when damaged neurons elicit an activation response by glia. However, an accumulating body of evidence has challenged this earlier perspective and indicates a more active role of neuroinflammation in the pathophysiology of progressive neurodegenerative disorders such as AD, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. This insight into pathophysiology evolved in concert with the appreciation that the brain is not as immunologically privileged as once thought. The central nervous system (CNS) has its own resident immune system, in which glial cells (microglia, astrocytes, and oligodendrocytes) not only serve supportive and nutritive roles for neurons but also engage from time to time in several "inflammatory" processes that defend the CNS from pathogens and help it to recover from stress and injury. These otherwise "normal" glial functions can sometimes result in a more severe and chronic neuroinflammatory cycle that actually promotes or propagates neurodegenerative disease. Excessive glial cell activation may thus constitute a viable target for the discovery of and development of neurodegenerative disease therapeutics. Suggestive clinical evidence in support of neuroinflammation as a drug discovery target for chronic neurodegenerative diseases, such as AD, comes from epidemiological and genetic linkage data. For example, long-term use of nonsteroidal anti-inflammatory drugs is correlated with a protective effect against AD, and certain polymorphisms in the genes for interleukin 1 and other proinflammatory mediator genes are associated with increased risk. In AD and Parkinson's disease, activated microglia and complement proteins have been identified in the brain regions most affected in these disorders. This report will briefly review selected clinical and preclinical data that reflect the prevailing approaches targeting neuroinflammation as a pathophysiological process contributing to the onset or progression of neurodegenerative diseases, as well as their neuroprotective potential.
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Affiliation(s)
- Stephen D Skaper
- Neurodegeneration Research Department, Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Limited, Harlow, Essex CM19 5 AW, United Kingdom.
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Matute C, Torre I, Pérez-Cerdá F, Pérez-Samartín A, Alberdi E, Etxebarria E, Arranz AM, Ravid R, Rodríguez-Antigüedad A, Sánchez-Gómez M, Domercq M. P2X(7) receptor blockade prevents ATP excitotoxicity in oligodendrocytes and ameliorates experimental autoimmune encephalomyelitis. J Neurosci 2007; 27:9525-33. [PMID: 17728465 PMCID: PMC6673129 DOI: 10.1523/jneurosci.0579-07.2007] [Citation(s) in RCA: 304] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oligodendrocyte death and demyelination are hallmarks of multiple sclerosis (MS). Here we show that ATP signaling can trigger oligodendrocyte excitotoxicity via activation of calcium-permeable P2X(7) purinergic receptors expressed by these cells. Sustained activation of P2X(7) receptors in vivo causes lesions that are reminiscent of the major features of MS plaques, i.e., demyelination, oligodendrocyte death, and axonal damage. In addition, treatment with P2X(7) antagonists of chronic experimental autoimmune encephalomyelitis (EAE), a model of MS, reduces demyelination and ameliorates the associated neurological symptoms. Together, these results indicate that ATP can kill oligodendrocytes via P2X(7) activation and that this cell death process contributes to EAE. Importantly, P2X(7) expression is elevated in normal-appearing axon tracts in MS patients, suggesting that signaling through this receptor in oligodendrocytes may be enhanced in this disease. Thus, P2X(7) receptor antagonists may be beneficial for the treatment of MS.
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MESH Headings
- Adenosine Triphosphate/toxicity
- Animals
- Animals, Newborn
- Calcium/metabolism
- Cell Survival/drug effects
- Cell Survival/physiology
- Cells, Cultured
- Encephalomyelitis, Autoimmune, Experimental/chemically induced
- Encephalomyelitis, Autoimmune, Experimental/therapy
- Glial Fibrillary Acidic Protein/metabolism
- Glycoproteins
- Humans
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Membrane Potentials/radiation effects
- Mice
- Microscopy, Immunoelectron/methods
- Myelin Basic Protein/metabolism
- Myelin-Oligodendrocyte Glycoprotein
- Oligodendroglia/drug effects
- Oligodendroglia/metabolism
- Oligodendroglia/ultrastructure
- Optic Nerve/cytology
- Optic Nerve/pathology
- Optic Nerve/ultrastructure
- Patch-Clamp Techniques/methods
- Peptide Fragments
- Platelet Aggregation Inhibitors
- Purinergic P2 Receptor Antagonists
- Rats
- Rats, Sprague-Dawley
- Receptors, Purinergic P2/physiology
- Receptors, Purinergic P2X7
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Affiliation(s)
- Carlos Matute
- Departamento de Neurociencias, Universidad del País Vasco, 48940 Leioa, Spain.
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60
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Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
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61
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Matute C, Alberdi E, Domercq M, Sánchez-Gómez MV, Pérez-Samartín A, Rodríguez-Antigüedad A, Pérez-Cerdá F. Excitotoxic damage to white matter. J Anat 2007; 210:693-702. [PMID: 17504270 PMCID: PMC2375761 DOI: 10.1111/j.1469-7580.2007.00733.x] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Glutamate kills neurons by excitotoxicity, which is caused by sustained activation of glutamate receptors. In recent years, it has been shown that glutamate can also be toxic to white matter oligodendrocytes and to myelin by this mechanism. In particular, glutamate receptor-mediated injury to these cells can be triggered by activation of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, kainate and N-methyl-D-aspartate glutamate receptor types. Thus, these receptor classes, and the intermediaries of the signal cascades they activate, are potential targets for drug development to treat white matter damage in acute and chronic diseases. In addition, alterations of glutamate homeostasis in white matter can determine glutamate injury to oligodendrocytes and myelin. Astrocytes are responsible for most glutamate uptake in synaptic and non-synaptic areas and consequently are the major regulators of glutamate homeostasis. Activated microglia in turn may secrete cytokines and generate radical oxygen species, which impair glutamate uptake and reduce the expression of glutamate transporters. Finally, oligodendrocytes also contribute to glutamate homeostasis. This review aims at summarizing the current knowledge about the mechanisms leading to oligodendrocyte cell death and demyelination as a consequence of alterations in glutamate signalling, and their clinical relevance to disease. In addition, we show evidence that oligodendrocytes can also be killed by ATP acting at P2X receptors. A thorough understanding of how oligodendrocytes and myelin are damaged by excitotoxicity will generate knowledge that can lead to improved therapeutic strategies to protect white matter.
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Affiliation(s)
- Carlos Matute
- Departamento de Neurociencias, Universidad del País Vasco, Leioa, and Neurotek-UPV/EHU, Parque Tecnológico deBizkaia, Zamudio, Spain. carlos.,
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62
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Lister MF, Sharkey J, Sawatzky DA, Hodgkiss JP, Davidson DJ, Rossi AG, Finlayson K. The role of the purinergic P2X7 receptor in inflammation. J Inflamm (Lond) 2007; 4:5. [PMID: 17367517 PMCID: PMC1838907 DOI: 10.1186/1476-9255-4-5] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Accepted: 03/16/2007] [Indexed: 01/06/2023] Open
Abstract
The inflammatory process, orchestrated against a variety of injurious stimuli, is composed of three inter-related phases; initiation, propagation and resolution. Understanding the interplay between these three phases and harnessing the beneficial properties of inflammation whilst preventing its damaging effects, will undoubtedly lead to the advent of much needed therapies, particularly in chronic disease states. The P2X7 receptor (P2X7R) is increasingly recognised as an important cell surface regulator of several key inflammatory molecules including IL-1beta, IL-18, TNF-alpha and IL-6. Moreover, as P2X7R-dependent cytokine production is driven by activating the inflammasome, antagonists of this receptor are likely to have therapeutic potential as novel anti-inflammatory therapies. The function of the P2X7R in inflammation, immunity and its potential role in disease will be reviewed and discussed.
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Affiliation(s)
- Martin F Lister
- MRC Centre for Inflammation Research, The Queen's Medical Research Institute, The University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - John Sharkey
- Astellas CNS Research in Edinburgh, The Chancellor's Building, The University of Edinburgh, 49 Little France Crescent, EH16 4SB, UK
| | - Deborah A Sawatzky
- MRC Centre for Inflammation Research, The Queen's Medical Research Institute, The University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Joseph P Hodgkiss
- Astellas CNS Research in Edinburgh, The Chancellor's Building, The University of Edinburgh, 49 Little France Crescent, EH16 4SB, UK
| | - Donald J Davidson
- MRC Centre for Inflammation Research, The Queen's Medical Research Institute, The University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Adriano G Rossi
- MRC Centre for Inflammation Research, The Queen's Medical Research Institute, The University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Keith Finlayson
- Astellas CNS Research in Edinburgh, The Chancellor's Building, The University of Edinburgh, 49 Little France Crescent, EH16 4SB, UK
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63
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Skaper SD, Facci L, Culbert AA, Evans NA, Chessell I, Davis JB, Richardson JC. P2X(7) receptors on microglial cells mediate injury to cortical neurons in vitro. Glia 2006; 54:234-42. [PMID: 16817206 DOI: 10.1002/glia.20379] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The P2X(7) receptor has been implicated in the release of cytokines and in the induction of cell death, and is up-regulated in a transgenic mouse model of Alzheimer's disease. Using cocultures of rat cortical neurons and microglia, we show that ATP and the more potent P2X(7) agonist benzoylbenzoyl-ATP (BzATP) cause neuronal cell injury. The deleterious effects of BzATP-treated microglia were prevented by nonselective P2X antagonists (PPADS and oxidized ATP) and by the more selective P2X(7) antagonist Brilliant Blue G. Similar concentrations of BzATP caused release of superoxide and nitric oxide from isolated microglia, and neuronal cell injury was attenuated by a superoxide dismutase mimetic and by a peroxynitrite decomposition catalyst, suggesting a role for reactive oxide species. Cocultures composed of wild-type cortical neurons, and microglia from P2X(7) receptor-deficient mice failed to exhibit neuronal cell injury in the presence of BzATP, but retained sensitivity to injury when microglia were derived from genotypically matched normal (P2X(7) (+/+) mice), thereby establishing P2X(7) involvement in the injury process. P2X(7) receptor activation on microglia thus appears necessary for microglial-mediated injury of neurons, and proposes that targeting P2X(7) receptors may constitute a novel approach for the treatment of acute and chronic neurodegenerative disorders where a microglial component is evident.
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Affiliation(s)
- Stephen D Skaper
- Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Limited, New Frontiers Science Park, Third Avenue, Harlow CM19 5AW, Essex, United Kingdom.
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64
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Young MT, Pelegrin P, Surprenant A. Identification of Thr283 as a key determinant of P2X7 receptor function. Br J Pharmacol 2006; 149:261-8. [PMID: 16940988 PMCID: PMC2014266 DOI: 10.1038/sj.bjp.0706880] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE The ATP-gated P2X(7) receptor is an unusual ion channel that couples to multiple downstream signalling cascades. We noted differences in mouse cDNA sequences that may indicate polymorphisms; the aim of this study was to compare function and expression of these mouse P2X(7) receptor mutations. EXPERIMENTAL APPROACH There are three differences in the sequences of P2X(7) cDNA cloned from mouse NTW8 microglial cells or C57 BL/6 mice: [Phe(11),Ala(221),Met(283)]P2X(7) in the former and [Leu(11),Thr(221),Thr(283)]P2X(7) in the latter. We expressed these receptors and measured membrane currents, ethidium uptake, calcium influx and surface membrane expression. We also carried out these assays on the previously described polymorphism observed between C57 BL/6 and Balb/c mice ([Leu(451)]P2X(7) vs [Pro(451)]P2X(7)). KEY RESULTS Maximum current densities at [Phe(11),Ala(221),Met(283)]P2X(7) were <12% of those at [Leu(11),Thr(221),Thr(283)]P2X(7) without change in the agonist concentration-response. Replacing methionine with threonine at residue 283 yielded a receptor whose properties were the same as [Leu(11),Thr(221),Thr(283)]P2X(7). Replacing T283 in the rat P2X(7) receptor with methionine yielded currents that were <10% of wildtype and no ethidium uptake was associated with its activation. Maximum current densities and agonist EC(50) values were the same at mouse [Thr(283),Leu(451)]P2X(7) and [Thr(283),Pro(451)]P2X(7) but ethidium uptake and Fluo4 fluorescence were significantly reduced at the [Thr(283),Leu(451)]P2X(7) receptor. There was equivalent surface membrane expression of all P2X(7) receptors. CONCLUSIONS This study has revealed a residue (Thr(283)) in the ectodomain that is critical for P2X(7) receptor function and suggests that the intracellular residue 451 alters downstream signalling independently of ion channel activity.
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Affiliation(s)
- M T Young
- Department of Biomedical Science, University of Sheffield, Florey Building, Western Bank Sheffield, UK
| | - P Pelegrin
- Department of Biomedical Science, University of Sheffield, Florey Building, Western Bank Sheffield, UK
| | - A Surprenant
- Department of Biomedical Science, University of Sheffield, Florey Building, Western Bank Sheffield, UK
- Author for correspondence:
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65
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Lai AY, Todd KG. Microglia in cerebral ischemia: molecular actions and interactions. Can J Physiol Pharmacol 2006; 84:49-59. [PMID: 16845890 DOI: 10.1139/y05-143] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The precise role of microglia in stroke and cerebral ischemia has been the subject of debate for a number of years. Microglia are capable of synthesizing numerous soluble and membrane-bound biomolecules, some known to be neuroprotective, some neurotoxic, whereas others have less definitive bioactivities. The molecular mechanisms through which microglia activate these molecules have thus become an important area of ischemia research. Here we provide a survey review that summarizes the key actions of microglial factors in cerebral ischemia including complement proteins, chemokines, pro-inflammatory cytokines, neurotrophic factors, hormones, and proteinases, as well several important messenger molecules that play a part in how these factors respond to extracellular signals during ischemic injuries. We also provide some new perspectives on how microglial intracellular signaling may contribute to the seemingly contradictory roles of several microglial effector molecules.
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Affiliation(s)
- Aaron Y Lai
- Neurochemical Research Unit, Department of Psychiatry and Centre for Neuroscience, University of Alberta, Edmonton, Canada
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66
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Melani A, Amadio S, Gianfriddo M, Vannucchi MG, Volontè C, Bernardi G, Pedata F, Sancesario G. P2X7 receptor modulation on microglial cells and reduction of brain infarct caused by middle cerebral artery occlusion in rat. J Cereb Blood Flow Metab 2006; 26:974-82. [PMID: 16395292 DOI: 10.1038/sj.jcbfm.9600250] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adenosine 5'-triphosphate outflow increases after an ischemic insult in the brain and may induce the expression of P2X7 receptors in resting microglia, determining its modification into an activated state. To assess the effects of P2X7 receptor blockade in preventing microglia activation and ameliorating brain damage and neurological impairment, we delivered the P2 unselective antagonist Reactive Blue 2 to rats after middle cerebral artery occlusion. In sham-operated animals, devoid of brain damage, double immunofluorescence verified the absence of P2X7 immunoreactivity on resting microglia, astrocytes, and neurons, identified, respectively, by OX-42, glial fibrillary acid protein, and neuronal nuclei (NeuN) immunoreactivity. After ischemia, vehicle-treated rats showed monolateral sensorimotor deficit and tissue damage in striatum and frontoparietal cortex. Moreover, P2X7 immunoreactivity was de novo expressed on activated microglia in infarcted and surrounding areas, as well as on a reactive form of microglia, resting in shape but P2X7 immunoreactive, present in ipsi- and contralateral cingulate and medial frontal cortex. Reactive Blue 2 improved sensorimotor deficit and restricted the volume of infarction, without preventing the expression of P2X7, but inducing it in the microglia of contralateral frontal and parietal cortex and striatum, which had lost reciprocal connections with the remote infarct area. De novo expression of P2X7 occurred in both activated and reactive microglia, suggesting their differentiated roles in the area of infarct and in remote regions. Reactive Blue 2 reduced ischemic brain damage, likely blocking the function of activated microglia in the infarct area, but in the remote brain regions promoted the expression of P2X7 on reactive microglia, developing defense and reparative processes.
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Affiliation(s)
- Alessia Melani
- Department of Preclinical and Clinical Pharmacology, University of Florence, Florence, Italy
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67
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Gever JR, Cockayne DA, Dillon MP, Burnstock G, Ford APDW. Pharmacology of P2X channels. Pflugers Arch 2006; 452:513-37. [PMID: 16649055 DOI: 10.1007/s00424-006-0070-9] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 03/08/2006] [Indexed: 02/07/2023]
Abstract
Significant progress in understanding the pharmacological characteristics and physiological importance of homomeric and heteromeric P2X channels has been achieved in recent years. P2X channels, gated by ATP and most likely trimerically assembled from seven known P2X subunits, are present in a broad distribution of tissues and are thought to play an important role in a variety of physiological functions, including peripheral and central neuronal transmission, smooth muscle contraction, and inflammation. The known homomeric and heteromeric P2X channels can be distinguished from each other on the basis of pharmacological differences when expressed recombinantly in cell lines, but whether this pharmacological classification holds true in native cells and in vivo is less well-established. Nevertheless, several potent and selective P2X antagonists have been discovered in recent years and shown to be efficacious in various animal models including those for visceral organ function, chronic inflammatory and neuropathic pain, and inflammation. The recent advancement of drug candidates targeting P2X channels into human trials, confirms the medicinal exploitability of this novel target family and provides hope that safe and effective medicines for the treatment of disorders involving P2X channels may be identified in the near future.
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Affiliation(s)
- Joel R Gever
- Department of Biochemical Pharmacology, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, USA.
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68
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Franke H, Krügel U, Illes P. P2 receptors and neuronal injury. Pflugers Arch 2006; 452:622-44. [PMID: 16645849 DOI: 10.1007/s00424-006-0071-8] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 03/09/2006] [Indexed: 02/08/2023]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) was proposed to be an activity-dependent signaling molecule that regulates glia-glia and glia-neuron communications. ATP is a neurotransmitter of its own right and, in addition, a cotransmitter of other classical transmitters such as glutamate or GABA. The effects of ATP are mediated by two receptor families belonging either to the P2X (ligand-gated cationic channels) or P2Y (G protein-coupled receptors) types. P2X receptors are responsible for rapid synaptic responses, whereas P2Y receptors mediate slow synaptic responses and other types of purinergic signaling involved in neuronal damage/regeneration. ATP may act at pre- and postsynaptic sites and therefore, it may participate in the phenomena of long-term potentiation and long-term depression of excitatory synaptic transmission. The release of ATP into the extracellular space, e.g., by exocytosis, membrane transporters, and connexin hemichannels, is a widespread physiological process. However, ATP may also leave cells through their plasma membrane damaged by inflammation, ischemia, and mechanical injury. Functional responses to the activation of multiple P2 receptors were found in neurons and glial cells under normal and pathophysiological conditions. P2 receptor-activation could either be a cause or a consequence of neuronal cell death/glial activation and may be related to detrimental and/or beneficial effects. The present review aims at demonstrating that purinergic mechanisms correlate with the etiopathology of brain insults, especially because of the massive extracellular release of ATP, adenosine, and other neurotransmitters after brain injury. We will focus in this review on the most important P2 receptor-mediated neurodegenerative and neuroprotective processes and their beneficial modulation by possible therapeutic manipulations.
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Affiliation(s)
- Heike Franke
- Rudolf-Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
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69
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Alloisio S, Aiello R, Ferroni S, Nobile M. Potentiation of native and recombinant P2X7-mediated calcium signaling by arachidonic acid in cultured cortical astrocytes and human embryonic kidney 293 cells. Mol Pharmacol 2006; 69:1975-83. [PMID: 16510558 DOI: 10.1124/mol.105.020164] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In the brain, arachidonic acid (AA) plays a critical role in the modulation of a broad spectrum of biological responses, including those underlying neuroinflammation. By using microfluorometry, we investigated the action of extracellular AA in the modulation of the purinoceptor P2X7-mediated elevation of [Ca(2+)](i) in cultured neocortical type-1 astrocytes and P2X7-, P2X2-transfected human embryonic kidney (HEK) 293 cells. We report that in cultured astrocytes, AA-induced [Ca(2+)](i) elevation is coupled to depletion of intracellular Ca(2+) stores and to a sustained noncapacitative Ca(2+) entry. AA also induced a robust potentiation of the astrocytic P2X7-mediated [Ca(2+)](i) rise evoked by the selective agonist 3'-O-(4-benzoyl)benzoyl-ATP (BzATP). Pharmacological studies demonstrate that the selective P2X7 antagonists oxidized ATP and Brilliant Blue G abrogated the AA-mediated potentiation of BzATP-evoked [Ca(2+)](i) elevation. Fluorescent dye uptake experiments showed that the AA-induced increase in [Ca(2+)](i) was not due to a switch of the P2X7 receptor from channel to the pore mode of gating. The synergistic effect of AA and BzATP was also observed in HEK293 cells stably expressing rat and human P2X7 but not in rat P2X2. Control HEK293 cells responded to AA exposure only with a transient [Ca(2+)](i) elevation, whereas in those expressing the P2X7 receptor, AA elicited a potentiation of the BzATP-induced [Ca(2+)](i) rise. Together, these findings indicate that AA mediates a complex regulation of [Ca(2+)](i) dynamics also through P2X7-mediated Ca(2+) entry, suggesting that variations in AA production may be relevant to the control of both the temporal and spatial kinetics of [Ca(2+)](i) signaling in astroglial cells.
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Affiliation(s)
- Susanna Alloisio
- Institute of Biophysics, Consiglio Nazionale delle Richerche, Via De Marini 6, 16149 Genoa, Italy
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70
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Marty V, Médina C, Combe C, Parnet P, Amédée T. ATP binding cassette transporter ABC1 is required for the release of interleukin-1beta by P2X7-stimulated and lipopolysaccharide-primed mouse Schwann cells. Glia 2005; 49:511-9. [PMID: 15578659 DOI: 10.1002/glia.20138] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Schwann cells are best known as myelinating glial cells of the peripheral nervous system, but they also participate actively in the sphere of immunity by producing pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta). In a previous study, we demonstrated that posttranslational processing of IL-1beta by immune-challenged Schwann cells required the P2X7 receptor. Remarkably, the release of IL-1beta was not associated with cell death, indicating the involvement of an active mechanism. ATP binding cassette (ABC) transporters are known to transport leaderless secretory proteins, such as IL-1beta; therefore, we investigated whether such transporters were at work in Schwann cells. Mouse Schwann cells expressed ABC1 transporter mRNA and displayed the functional protein. Glybenclamide and diisothiocyanato-stilbene-disulfonic acid (DIDS), two blockers of chloride fluxes that drive the export activity of ABC1 transporters, inhibited IL-1beta release without altering its intracellular processing. Enhancing chloride efflux potentiated the release of IL-1beta, while decreasing it led to a strong reduction in its release. Because the stimulation of the P2X7 receptor also activates a chloride conductance, we investigated the possibility of a sole anionic pathway mobilized by the P2X7 receptor and ABC1. Glybenclamide and DIDS had no significant effects on the P2X7-activated chloride current suggesting therefore the existence of two different pathways. In summary, ABC1 transporters are required for the release of IL-1beta by mouse Schwann cells. Being associated together with chloride conductance, P2X7 receptors and ABC1 transporters delineate a subtle and complex regulation of IL-1beta production in mammalian Schwann cells. Furthermore, ABC1 transporters could be a target of therapeutic interest for regulating IL-1beta activity in neuroinflammation disorders.
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Affiliation(s)
- Vincent Marty
- Laboratoire de Neurobiologie Intégrative, Université Victor Segalen Bordeaux 2, Institut François Magendie, Bordeaux, France
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71
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Franke H, Günther A, Grosche J, Schmidt R, Rossner S, Reinhardt R, Faber-Zuschratter H, Schneider D, Illes P. P2X7 receptor expression after ischemia in the cerebral cortex of rats. J Neuropathol Exp Neurol 2004; 63:686-99. [PMID: 15290894 DOI: 10.1093/jnen/63.7.686] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Large amounts of adenosine 5'-triphosphate (ATP) released from cellular sources under pathological conditions such as ischemia may activate purinoceptors of the P2X and P2Y types. In the present study, the expression of the P2X7 receptor-subtype in the brain cortex of spontaneously hypertensive rats was investigated using a permanent focal cerebral ischemia model. Immunocytochemistry with antibodies raised against the intracellular C-terminus of the P2X7 receptor showed a time-dependent upregulation of labeled cells in the peri-infarct region after right middle cerebral artery occlusion (MCAO) in comparison to controls. Double immunofluorescence visualized with confooal laser scanning microscopy indicated the localization of the P2X7 receptor after ischemia on microglial cells (after 1 and 4 days), on tubulin betaIII-labeled neurons (after 4 and 7 days), and on glial fibrillary acidic protein (GFAP)-positive astrocytes (after 4 days). In the following experiments, changes occurring 4 days after MCAO were investigated in detail. Western blot analysis of the cortical tissue around the area of necrosis indicated an increase in the P2X7 receptor protein. Immunoelectron microscopy revealed the receptor localization on synapses (presynaptically), on dendrites, as well as on the nuclear membrane of neurons (postsynaptically) and glial cells. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling in combination with P2X7 receptor immunocytochemistry indicated a co-expression on the apoptotic cells. Active caspase 3 was especially observed on GFAP-positive astrocytes. In conclusion, the present data demonstrate a postischemic, time-dependent upregulation of the P2X7 receptor-subtype on neurons and glial cells and suggest a role for this receptor in the pathophysiology of cerebral ischemia in vivo.
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Affiliation(s)
- Heike Franke
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.
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72
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Wang X, Arcuino G, Takano T, Lin J, Peng WG, Wan P, Li P, Xu Q, Liu QS, Goldman SA, Nedergaard M. P2X7 receptor inhibition improves recovery after spinal cord injury. Nat Med 2004; 10:821-7. [PMID: 15258577 DOI: 10.1038/nm1082] [Citation(s) in RCA: 397] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 06/25/2004] [Indexed: 01/29/2023]
Abstract
Secondary injury exacerbates the extent of spinal cord insults, yet the mechanistic basis of this phenomenon has largely been unexplored. Here we report that broad regions of the peritraumatic zone are characterized by a sustained process of pathologic, high ATP release. Spinal cord neurons expressed P2X7 purine receptors (P2X7R), and exposure to ATP led to high-frequency spiking, irreversible increases in cytosolic calcium and cell death. To assess the potential effect of P2X7R blockade in ameliorating acute spinal cord injury (SCI), we delivered P2X7R antagonists OxATP or PPADS to rats after acute impact injury. We found that both OxATP and PPADS significantly improved functional recovery and diminished cell death in the peritraumatic zone. These observations demonstrate that SCI is associated with prolonged purinergic receptor activation, which results in excitotoxicity-based neuronal degeneration. P2X7R antagonists inhibit this process, reducing both the histological extent and functional sequelae of acute SCI.
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Affiliation(s)
- Xiaohai Wang
- Department of Neurosurgery, Center for Aging and Developmental Biology, University of Rochester Medical Center, Rochester, New York 14642, USA
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73
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Sim JA, Young MT, Sung HY, North RA, Surprenant A. Reanalysis of P2X7 receptor expression in rodent brain. J Neurosci 2004; 24:6307-14. [PMID: 15254086 PMCID: PMC6729549 DOI: 10.1523/jneurosci.1469-04.2004] [Citation(s) in RCA: 214] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 05/25/2004] [Accepted: 05/26/2004] [Indexed: 01/08/2023] Open
Abstract
P2X receptors are cationic-selective ion channels gated by extracellular ATP. There are seven subunits (P2X1-7), the first six of which are expressed throughout the peripheral and central nervous systems. P2X7 receptors are rapidly upregulated and activated as a result of inflammatory stimuli in immune cells, where they act not only as cationic channels but uniquely couple with rapid release of proinflammatory cytokines, cytoskeletal rearrangements, and apoptosis or necrotic cell death. The P2X7 receptor has been termed the cytolytic non-neuronal P2X receptor because it had not been detected in neurons until recently when it has been immunolocalized to several brain regions, particularly the hippocampus, and has been suggested to be involved in presynaptic modulation of transmitter release. Because its expression in brain neurons may have substantial functional implications, we have performed detailed immunocytochemical, immunoblot, and immunoprecipitation studies on brain and non-neuronal tissue using all currently available antibodies. We first examined rats, but staining patterns were inconsistent among antibodies; we therefore studied mice for which there are two P2X7 knock-out mice constructs available, one expressing the LacZ transgene. We found that P2X7 receptor protein is strongly and reliably detected in the submandibular gland and lung of wild-type mice but not in either of the P2X7-/- mice. However, we failed to find evidence for P2X7 receptor protein in hippocampal neurons or their input-output projections. Either the P2X7 protein in the hippocampus is below the limits of detection by the currently available methods or it is not present.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Brain Chemistry
- Crosses, Genetic
- Epitopes/immunology
- Hippocampus/chemistry
- Immunoprecipitation
- Lac Operon
- Lung/chemistry
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Knockout
- Nerve Tissue Proteins/analysis
- Nerve Tissue Proteins/deficiency
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/immunology
- Neurons/chemistry
- Organ Specificity
- Rats
- Rats, Wistar
- Receptors, Purinergic P2/analysis
- Receptors, Purinergic P2/deficiency
- Receptors, Purinergic P2/genetics
- Receptors, Purinergic P2/immunology
- Receptors, Purinergic P2X7
- Submandibular Gland/chemistry
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Affiliation(s)
- Joan A Sim
- Institute of Molecular Physiology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom
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74
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Cavaliere F, Amadio S, Sancesario G, Bernardi G, Volonté C. Synaptic P2X7 and oxygen/glucose deprivation in organotypic hippocampal cultures. J Cereb Blood Flow Metab 2004; 24:392-8. [PMID: 15087708 DOI: 10.1097/00004647-200404000-00004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The P2X7 receptor for extracellular ATP is the main candidate, among P2 receptors, inducing cell death in the immune system. Here, we demonstrate the direct participation of this receptor to cell damage induced by oxygen/glucose deprivation, in the ex vivo model of organotypic hippocampal cultures. By pharmacological and immunological approaches, we show that P2X7 is rapidly and transiently up regulated in hippocampal areas eliciting metabolism impairment. Moreover, the P2 antagonists 2',3',-dialdehyde ATP and reactive blue 2 prevent both up regulation of this receptor and hypoxic/hypoglycemic damage. By confocal laser microscopy, we show that P2X7 is present at the synaptic level of fibers extending from the CA1-2 pyramidal cell layer throughout the strata oriens and radiatum, but absent on oligodendrocytes, astrocytes or neuronal cell bodies. Colocalization of P2X7 is obtained with neurofilament-L protein and with synaptophysin, not with myelin basic protein, glial fibrillary acidic protein or a marker for neuronal nuclei. P2X7 up regulation and diffuse cellular damage are also induced by 3'-O-(4-benzoyl) benzoyl-ATP, an agonist selective but not exclusive for P2X7. In summary, our study demonstrates that P2X7 not only directly participates to the hypoxic/hypoglycemic process, but also owns specific phenotypic localization. We do not exclude that it might serve as a sensor of dysregulated neuronal activity and ATP release, both occurring during oxygen/glucose deprivation.
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