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Xie RG, Xu GY, Wu SX, Luo C. Presynaptic glutamate receptors in nociception. Pharmacol Ther 2023; 251:108539. [PMID: 37783347 DOI: 10.1016/j.pharmthera.2023.108539] [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: 05/26/2023] [Revised: 08/19/2023] [Accepted: 09/25/2023] [Indexed: 10/04/2023]
Abstract
Chronic pain is a frequent, distressing and poorly understood health problem. Plasticity of synaptic transmission in the nociceptive pathways after inflammation or injury is assumed to be an important cellular basis for chronic, pathological pain. Glutamate serves as the main excitatory neurotransmitter at key synapses in the somatosensory nociceptive pathways, in which it acts on both ionotropic and metabotropic glutamate receptors. Although conventionally postsynaptic, compelling anatomical and physiological evidence demonstrates the presence of presynaptic glutamate receptors in the nociceptive pathways. Presynaptic glutamate receptors play crucial roles in nociceptive synaptic transmission and plasticity. They modulate presynaptic neurotransmitter release and synaptic plasticity, which in turn regulates pain sensitization. In this review, we summarize the latest understanding of the expression of presynaptic glutamate receptors in the nociceptive pathways, and how they contribute to nociceptive information processing and pain hypersensitivity associated with inflammation / injury. We uncover the cellular and molecular mechanisms of presynaptic glutamate receptors in shaping synaptic transmission and plasticity to mediate pain chronicity, which may provide therapeutic approaches for treatment of chronic pain.
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Affiliation(s)
- Rou-Gang Xie
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
| | - Guang-Yin Xu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases, Institute of Neuroscience, Soochow University, Suzhou 215123, China
| | - Sheng-Xi Wu
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
| | - Ceng Luo
- Department of Neurobiology, Fourth Military Medical University, Xi'an 710032, China.
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2
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Srivastava A, Liachenko S, Sarkar S, Paule M, Negi G, Pandey JP, Hanig JP. Quantitative Neurotoxicology: An Assessment of the Neurotoxic Profile of Kainic Acid in Sprague Dawley Rats. Int J Toxicol 2020; 39:294-306. [PMID: 32468881 DOI: 10.1177/1091581820928497] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study consisted of a qualitative and quantitative assessment of neuropathological changes in kainic acid (KA)-treated adult male rats. Rats were administered a single 10 mg/kg intraperitoneal injection of KA or the same volume of saline and sacrificed 24 or 48 hours posttreatment. Brains were collected, sectioned coronally (∼ 81 slices), and stained with amino cupric silver to reveal degenerative changes. For qualitative assessment of neural degeneration, sectioned material was evaluated by a board-certified pathologist, and the level of degeneration was graded based upon a 4-point scale. For measurement of quantitative neural degeneration in response to KA treatment, the HALO digital image analysis software tool was used. Quantitative measurements of specific regions within the brain were obtained from silver-stained tissue sections with quantitation based on stain color and optical density. This quantitative evaluation method identified degeneration primarily in the cerebral cortex, septal nuclei, amygdala, olfactory bulb, hippocampus, thalamus, and hypothalamus. The KA-produced neuronal degeneration in the cortex was primarily in the piriform, insular, rhinal, and cingulate areas. In the hippocampus, the dentate gyrus was found to be the most affected area. Our findings indicate global neurotoxicity due to KA treatment. Certain brain structures exhibited more degeneration than others, reflecting differential sensitivity or vulnerability of neurons to KA.
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Affiliation(s)
| | - Serguei Liachenko
- National Center for Toxicological Research, NCTR/DNT, Jefferson, AR, USA
| | - Sumit Sarkar
- National Center for Toxicological Research, NCTR/DNT, Jefferson, AR, USA
| | - Merle Paule
- National Center for Toxicological Research, NCTR/DNT, Jefferson, AR, USA
| | - Geeta Negi
- US Food and Drug Administration, CDER/OPQ, Silver Spring, MD, USA
| | - Jai P Pandey
- US Food and Drug Administration, CDER/OPQ, Silver Spring, MD, USA
| | - Joseph P Hanig
- US Food and Drug Administration, CDER/OPQ, Silver Spring, MD, USA
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3
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Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
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4
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Lin YC, Frei JA, Kilander MBC, Shen W, Blatt GJ. A Subset of Autism-Associated Genes Regulate the Structural Stability of Neurons. Front Cell Neurosci 2016; 10:263. [PMID: 27909399 PMCID: PMC5112273 DOI: 10.3389/fncel.2016.00263] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/28/2016] [Indexed: 12/15/2022] Open
Abstract
Autism spectrum disorder (ASD) comprises a range of neurological conditions that affect individuals’ ability to communicate and interact with others. People with ASD often exhibit marked qualitative difficulties in social interaction, communication, and behavior. Alterations in neurite arborization and dendritic spine morphology, including size, shape, and number, are hallmarks of almost all neurological conditions, including ASD. As experimental evidence emerges in recent years, it becomes clear that although there is broad heterogeneity of identified autism risk genes, many of them converge into similar cellular pathways, including those regulating neurite outgrowth, synapse formation and spine stability, and synaptic plasticity. These mechanisms together regulate the structural stability of neurons and are vulnerable targets in ASD. In this review, we discuss the current understanding of those autism risk genes that affect the structural connectivity of neurons. We sub-categorize them into (1) cytoskeletal regulators, e.g., motors and small RhoGTPase regulators; (2) adhesion molecules, e.g., cadherins, NCAM, and neurexin superfamily; (3) cell surface receptors, e.g., glutamatergic receptors and receptor tyrosine kinases; (4) signaling molecules, e.g., protein kinases and phosphatases; and (5) synaptic proteins, e.g., vesicle and scaffolding proteins. Although the roles of some of these genes in maintaining neuronal structural stability are well studied, how mutations contribute to the autism phenotype is still largely unknown. Investigating whether and how the neuronal structure and function are affected when these genes are mutated will provide insights toward developing effective interventions aimed at improving the lives of people with autism and their families.
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Affiliation(s)
- Yu-Chih Lin
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Jeannine A Frei
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Michaela B C Kilander
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Wenjuan Shen
- Laboratory of Neuronal Connectivity, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
| | - Gene J Blatt
- Laboratory of Autism Neurocircuitry, Program in Neuroscience, Hussman Institute for Autism, Baltimore MD, USA
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Kainic Acid-Induced Excitotoxicity Experimental Model: Protective Merits of Natural Products and Plant Extracts. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:972623. [PMID: 26793262 PMCID: PMC4697086 DOI: 10.1155/2015/972623] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 11/16/2015] [Accepted: 11/17/2015] [Indexed: 11/17/2022]
Abstract
Excitotoxicity is well recognized as a major pathological process of neuronal death in neurodegenerative diseases involving the central nervous system (CNS). In the animal models of neurodegeneration, excitotoxicity is commonly induced experimentally by chemical convulsants, particularly kainic acid (KA). KA-induced excitotoxicity in rodent models has been shown to result in seizures, behavioral changes, oxidative stress, glial activation, inflammatory mediator production, endoplasmic reticulum stress, mitochondrial dysfunction, and selective neurodegeneration in the brain upon KA administration. Recently, there is an emerging trend to search for natural sources to combat against excitotoxicity-associated neurodegenerative diseases. Natural products and plant extracts had attracted a considerable amount of attention because of their reported beneficial effects on the CNS, particularly their neuroprotective effect against excitotoxicity. They provide significant reduction and/or protection against the development and progression of acute and chronic neurodegeneration. This indicates that natural products and plants extracts may be useful in protecting against excitotoxicity-associated neurodegeneration. Thus, targeting of multiple pathways simultaneously may be the strategy to maximize the neuroprotection effect. This review summarizes the mechanisms involved in KA-induced excitotoxicity and attempts to collate the various researches related to the protective effect of natural products and plant extracts in the KA model of neurodegeneration.
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Key proteins of activating cell death can be predicted through a kainic acid-induced excitotoxic stress. BIOMED RESEARCH INTERNATIONAL 2015; 2015:478975. [PMID: 25695085 PMCID: PMC4324491 DOI: 10.1155/2015/478975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/16/2014] [Accepted: 10/17/2014] [Indexed: 11/23/2022]
Abstract
Epilepsy is a major neurological disorder characterized by spontaneous seizures accompanied by neurophysiological changes. Repeated seizures can damage the brain as neuronal death occurs. A better understanding of the mechanisms of brain cell death could facilitate the discovery of novel treatments for neurological disorders such as epilepsy. In this study, a model of kainic acid- (KA-) induced neuronal death was established to investigate the early protein markers associated with apoptotic cell death due to excitotoxic damage in the rat cortex. The results indicated that KA induces both apoptotic and necrotic cell death in the cortex. Incubation with high concentrations (5 and 500 μM, >75%) and low concentrations (0.5 pM: 95% and 50 nM: 8%) of KA for 180 min led to necrotic and apoptotic cell death, respectively. Moreover, proteomic analysis using two-dimensional gel electrophoresis and mass spectrometry demonstrated that antiapoptotic proteins, including heat shock protein 70, 3-mercaptopyruvate sulfurtransferase, tubulin-B-5, and pyruvate dehydrogenase E1 component subunit beta, were significantly higher in apoptosis than in necrosis induced by KA. Our findings provide direct evidence that several proteins are associated with apoptotic and necrotic cell death in excitotoxicity model. The results indicate that these proteins can be apoptotic biomarkers from the early stages of cell death.
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Shypshyna MS, Veselovsky NS. Presynaptic Ca²⁺-permeable AMPA-receptors modulate paired-pulse depression in nociceptive sensory synapses. Neurosci Lett 2014; 585:1-5. [PMID: 25445368 DOI: 10.1016/j.neulet.2014.11.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 11/10/2014] [Accepted: 11/12/2014] [Indexed: 10/24/2022]
Abstract
The role of Ca(2+)-permeable AMPA-receptors (CP-AMPARs) in the induction of paired-pulse depression (PPD) at glutamatergic nociceptive sensory synapses was examined in co-culture of rat's dorsal root ganglion and dorsal horn neurons. CP-AMPARs make a considerable contribution to excitatory postsynaptic currents recorded in DH neurons following action potential generation in nociceptive DRG neurons. Activation of CP-AMPARs during fast synaptic transmission induces strong PPD (with a 200 ms inter-pulse interval). Blockage of CP-AMPARs with Naspm (100 μM) results in most cases in a significant reduction of the PPD magnitude, also reversing to paired-pulse facilitation in some cases. However, loading of postsynaptic DH neurons with BAPTA (10 mM) did not alter the effect of Naspm (100 μM) on the paired-pulse ratio. Our data provide evidence that presynaptic CP-AMPARs in nociceptive sensory synapses regulate the magnitude of PPD and that postsynaptic Ca(2+)-permeable glutamatergic receptors are not required for PPD induction.
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Affiliation(s)
- Mariia S Shypshyna
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz str., Kiev 01024, Ukraine.
| | - Nikolai S Veselovsky
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, 4, Bogomoletz str., Kiev 01024, Ukraine.
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Ionotropic glutamate receptors and voltage-gated Ca²⁺ channels in long-term potentiation of spinal dorsal horn synapses and pain hypersensitivity. Neural Plast 2013; 2013:654257. [PMID: 24224102 PMCID: PMC3808892 DOI: 10.1155/2013/654257] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/27/2013] [Accepted: 08/27/2013] [Indexed: 12/18/2022] Open
Abstract
Over the last twenty years of research on cellular mechanisms of pain hypersensitivity, long-term potentiation (LTP) of synaptic transmission in the spinal cord dorsal horn (DH) has emerged as an important contributor to pain pathology. Mechanisms that underlie LTP of spinal DH neurons include changes in the numbers, activity, and properties of ionotropic glutamate receptors (AMPA and NMDA receptors) and of voltage-gated Ca2+ channels. Here, we review the roles and mechanisms of these channels in the induction and expression of spinal DH LTP, and we present this within the framework of the anatomical organization and synaptic circuitry of the spinal DH. Moreover, we compare synaptic plasticity in the spinal DH with classical LTP described for hippocampal synapses.
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Miyazaki S, Minami T, Mizuma H, Kanazawa M, Doi H, Matsumura S, Lu J, Onoe H, Furuta K, Suzuki M, Ito S. The action site of the synthetic kainoid (2S,3R,4R)-3-carboxymethyl-4-(4-methylphenylthio)pyrrolidine-2-carboxylic acid (PSPA-4), an analogue of Japanese mushroom poison acromelic acid, for allodynia (tactile pain). Eur J Pharmacol 2013; 710:120-7. [DOI: 10.1016/j.ejphar.2012.10.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 09/29/2012] [Accepted: 10/13/2012] [Indexed: 02/05/2023]
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Bhangoo SK, Swanson GT. Kainate receptor signaling in pain pathways. Mol Pharmacol 2012; 83:307-15. [PMID: 23095167 DOI: 10.1124/mol.112.081398] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Receptors and channels that underlie nociceptive signaling constitute potential sites of intervention for treatment of chronic pain states. The kainate receptor family of glutamate-gated ion channels represents one such candidate set of molecules. They have a prominent role in modulation of excitatory signaling between sensory and spinal cord neurons. Kainate receptors are also expressed throughout central pain neuraxis, where their functional contributions to neural integration are less clearly defined. Pharmacological inhibition or genetic ablation of kainate receptor activity reduces pain behaviors in a number of animal models of chronic pain, and small clinical trials have been conducted using several orthosteric antagonists. This review will cover kainate receptor function and participation in pain signaling as well as the pharmacological studies supporting further consideration as potential targets for therapeutic development.
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Affiliation(s)
- Sonia K Bhangoo
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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11
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Samengo I, Currò D, Navarra P, Barrese V, Taglialatela M, Martire M. Molecular and pharmacological evidence for a facilitatory functional role of pre-synaptic GLUK2/3 kainate receptors on GABA release in rat trigeminal caudal nucleus. Eur J Pain 2012; 16:1148-57. [PMID: 22392917 PMCID: PMC3444694 DOI: 10.1002/j.1532-2149.2012.00122.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Gamma-aminobutyric acid (GABA) and glutamate (GLU) are involved in nociceptive signals processing in the trigeminal system. In this study, we investigated the influence of excitatory transmission on GABA release in nerve terminals isolated from the rat trigeminal caudal nucleus (TCN). METHODS We utilize biochemical (superfused synaptosomes loaded with [(3) H]GABA) and morphological (immunofluorescence experiments with specific antibody) techniques. RESULTS Our results show that GLU potentiates the release of [(3) H]GABA evoked by 9, 15 and 30 mM [K(+)](e); 15 mM [K(+)](e)-evoked [(3) H]GABA release was also reinforced by domoate and kainate (KA), two naturally occurring GLU-receptor agonists. The enhancement of 15 mM [K(+)](e)-evoked [(3) H]GABA release produced by 100 μM KA was abolished by NBQX, a mixed AMPA/KA receptor antagonist, but was not affected by GYKI52466, a selective AMPA receptor antagonist. ATPA, a selective agonist for KA receptors containing the GLUK1 subunit, had no effect on depolarization-induced [(3) H]GABA release, and UBP310, which selectively antagonizes these same receptors, failed to reverse the KA-induced potentiation of 15 mM [K(+)](e)-evoked [(3) H]GABA release. The KA-induced potentiation was also unaffected by concanavalin A (10 μM), a positive allosteric modulator of GLUK1- and GLUK2-containing KA receptors. Immunofluorescence experiments revealed that GABAergic nerve terminals in the TCN differentially expressed GLUK subunits, with GLUK2/3-positive terminals being twice more abundant than GLUK1-containing synaptosomes. CONCLUSIONS These findings indicate that pre-synaptic KA receptors facilitating GABA release from TCN nerve terminals mainly express GLUK2/GLUK3 subunits, supporting the notion that different types of KA receptors are involved in the various stages of pain transmission.
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Affiliation(s)
- I Samengo
- Institute of Pharmacology, Catholic University of Sacred Heart, Rome, Italy
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Zhang XM, Zhu J. Kainic Acid-induced neurotoxicity: targeting glial responses and glia-derived cytokines. Curr Neuropharmacol 2012; 9:388-98. [PMID: 22131947 PMCID: PMC3131729 DOI: 10.2174/157015911795596540] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 09/28/2010] [Accepted: 10/18/2010] [Indexed: 01/01/2023] Open
Abstract
Glutamate excitotoxicity contributes to a variety of disorders in the central nervous system, which is triggered primarily by excessive Ca2+ influx arising from overstimulation of glutamate receptors, followed by disintegration of the endoplasmic reticulum (ER) membrane and ER stress, the generation and detoxification of reactive oxygen species as well as mitochondrial dysfunction, leading to neuronal apoptosis and necrosis. Kainic acid (KA), a potent agonist to the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate class of glutamate receptors, is 30-fold more potent in neuro-toxicity than glutamate. In rodents, KA injection resulted in recurrent seizures, behavioral changes and subsequent degeneration of selective populations of neurons in the brain, which has been widely used as a model to study the mechanisms of neurodegenerative pathways induced by excitatory neurotransmitter. Microglial activation and astrocytes proliferation are the other characteristics of KA-induced neurodegeneration. The cytokines and other inflammatory molecules secreted by activated glia cells can modify the outcome of disease progression. Thus, anti-oxidant and anti-inflammatory treatment could attenuate or prevent KA-induced neurodegeneration. In this review, we summarized updated experimental data with regard to the KA-induced neurotoxicity in the brain and emphasized glial responses and glia-oriented cytokines, tumor necrosis factor-α, interleukin (IL)-1, IL-12 and IL-18.
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Affiliation(s)
- Xing-Mei Zhang
- Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
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Abstract
Classically, glia have been regarded as non-excitable cells that provide nourishment and physical scaffolding for neurones. However, it is now generally accepted that glia are active participants in brain function that can modulate neuronal communication via several mechanisms. Investigations of anatomical plasticity in the magnocellular neuroendocrine system of the hypothalamic paraventricular and supraoptic nuclei led the way in the development of much of our understanding of glial regulation of neuronal activity. In this review, we provide an overview of glial regulation of magnocellular neurone activity from a historical perspective of the development of our knowledge of the morphological changes that are evident in the paraventricular and supraoptic nuclei. We also focus on recent data from the authors' laboratories presented at the 9th World Congress on Neurohypophysial Hormones that have contributed to our understanding of the multiple mechanisms by which glia modulate the activity of neurones, including: gliotransmitter modulation of synaptic transmission; trans-synaptic modulation by glial neurotransmitter transporter regulation of neurotransmitter spillover; and glial neurotransmitter transporter modulation of excitability by regulation of ambient neurotransmitter levels and their action on extrasynaptic receptors. The magnocellular neuroendocrine system secretes oxytocin and vasopressin from the posterior pituitary gland to control birth, lactation and body fluid balance, and we finally speculate as to whether glial regulation of individual magnocellular neurones might co-ordinate population activity to respond appropriately to altered physiological circumstances.
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Affiliation(s)
- Jeffrey G. Tasker
- Neurobiology Division, Department of Cell and Molecular Biology, Tulane University, New Orleans, LA, USA
| | - Stéphane H. R. Oliet
- Institut National de la Santé et de la Recherche Médicale, Unité 862, Université de Bordeaux, Bordeaux, France
| | - Jaideep S. Bains
- Hotchkiss Brain Institute and Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Colin H. Brown
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Javier E. Stern
- Department of Physiology, Georgia Health Sciences University, Augusta, GA, USA
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Oliet SHR, Bonfardin VDJ. Morphological plasticity of the rat supraoptic nucleus--cellular consequences. Eur J Neurosci 2011; 32:1989-94. [PMID: 21143653 DOI: 10.1111/j.1460-9568.2010.07514.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The supraoptic nuclei of the hypothalamus display a remarkable anatomical plasticity during lactation, parturition and chronic dehydration, conditions associated with massive neurohypophysial hormone secretion. This structural remodeling is characterized by a pronounced reduction of the astrocytic coverage of oxytocin neurons, resulting in an increase in the number and extent of directly juxtaposed neuronal surfaces. Although the exact role played by such an anatomical remodeling in the physiology of the hypothalamo-neurohypophysial system is still unknown, several findings obtained over the last decade indicate that synaptic and extrasynaptic transmissions are impacted by these structural changes. We review these data and try to extrapolate how such changes at the cellular level might affect the overall activity of the system. One repercussion of the retraction of glial processes is the accumulation of glutamate in the extracellular space. This build-up of glutamate causes an increased activation of pre-synaptic metabotropic glutamate receptors, which are negatively coupled to neurotransmitter release, and a switch in the mode of action of pre-synaptic kainate receptors that control GABA release. Finally, the range of action of substances released from astrocytes and acting on adjacent magnocellular neurons is also affected during the anatomical remodeling. It thus appears that the structural plasticity of the hypothalamic magnocellular nuclei strongly affects neuron-glial interactions and, as a consequence, induces significant changes in synaptic and extrasynaptic transmission.
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Affiliation(s)
- Stéphane H R Oliet
- Inserm U862, Neurocentre Magendie, 146 rue Léo Saignat, 33077 Bordeaux, France.
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15
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Schomburg ED, Dibaj P, Steffens H. Differentiation between Aδ and C fibre evoked nociceptive reflexes by TTX resistance and opioid sensitivity in the cat. Neurosci Res 2011; 69:241-5. [PMID: 21147180 DOI: 10.1016/j.neures.2010.12.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 11/24/2010] [Accepted: 12/05/2010] [Indexed: 11/27/2022]
MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Anesthetics, Local/pharmacology
- Animals
- Cats
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalin, Leucine/analogs & derivatives
- Enkephalin, Leucine/pharmacology
- Excitatory Postsynaptic Potentials/drug effects
- Female
- Foot/innervation
- Male
- Naloxone/pharmacology
- Narcotic Antagonists/pharmacology
- Nerve Fibers, Myelinated/drug effects
- Nerve Fibers, Myelinated/physiology
- Nerve Fibers, Unmyelinated/drug effects
- Nerve Fibers, Unmyelinated/physiology
- Nociceptors/drug effects
- Nociceptors/physiology
- Reflex/drug effects
- Spinal Cord/cytology
- Tetrodotoxin/pharmacology
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Affiliation(s)
- Eike D Schomburg
- Institute of Physiology, Georg August University of Göttingen, Waldweg 33, D-37073 Göttingen, Germany.
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16
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Antinociceptive effects of MSVIII-19, a functional antagonist of the GluK1 kainate receptor. Pain 2011; 152:1052-1060. [PMID: 21324591 DOI: 10.1016/j.pain.2011.01.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 12/16/2010] [Accepted: 01/11/2011] [Indexed: 11/21/2022]
Abstract
The ionotropic glutamate receptor subunit, GluK1 (GluR5), is expressed in many regions of the nervous system related to sensory transmission. Recently, a selective ligand for the GluK1 receptor, MSVIII-19 (8,9-dideoxy-neodysiherbaine), was synthesized as a derivative of dysiherbaine, a toxin isolated from the marine sponge Lendenfeldia chondrodes. MSVIII-19 potently desensitizes GluK1 receptors without channel activation, rendering it useful as a functional antagonist. Given the high selectivity for GluK1 and the proposed role for this glutamate receptor in nociception, we sought to test the analgesic potential of MSVIII-19 in a series of models of inflammatory, neuropathic, and visceral pain in mice. MSVIII-19 delivered intrathecally dose-dependently reduced formalin-induced spontaneous behaviors and reduced thermal hypersensitivity 3 hours after formalin injection and 24 hours after complete Freund's adjuvant-induced inflammation, but had no effect on mechanical sensitivity in the same models. Intrathecal MSVIII-19 significantly reduced both thermal hyperalgesia and mechanical hypersensitivity in the chronic constriction injury model of neuropathic pain, but had no effect in the acetic acid model of visceral pain. Peripheral administration of MSVIII-19 had no analgesic efficacy in any of these models. Finally, intrathecal MSVIII-19 did not alter responses in Tail-flick tests or performance on the accelerating RotaRod. These data suggest that spinal administration of MSVIII-19 reverses hypersensitivity in several models of pain in mice, supporting the clinical potential of GluK1 antagonists for the management of pain.
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Park SA, Park SJ, Han SK. Expression of KA1 kainate receptor subunit in the substantia gelatinosa of the trigeminal subnucleus caudalis in mice. J Vet Sci 2010; 11:299-304. [PMID: 21113098 PMCID: PMC2998740 DOI: 10.4142/jvs.2010.11.4.299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The KA1 kainate receptor (KAR) subunit in the substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) has been implicated in the processing of nociceptive information from the orofacial region. This study compared the expression of the KA1 KAR subunit in the SG of the Vc in juvenile, prepubescent and adult mice. RT-PCR, Western blot and immunohistochemistry analyses were used to examine the expression level in SG area. The expression levels of the KA1 KAR subunit mRNA and protein were higher in juvenile mice than in prepubescent or adult mice. Quantitative data revealed that the KA1 KAR subunit mRNA and protein were expressed at levels approximately two and three times higher, respectively, in juvenile mice than in adult mice. A similar expression pattern of the KA1 KAR subunit was observed in an immunohistochemical study that showed higher expression in the juvenile (59%) than those of adult (35%) mice. These results show that the KA1 KAR subunits are expressed in the SG of the Vc in mice and that the expression level of the KA1 KAR subunit decreases gradually with postnatal development. These findings suggest that age-dependent KA1 KAR subunit expression can be a potential mechanism of age-dependent pain perception.
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Affiliation(s)
- Seon Ah Park
- Department of Oral Physiology and BK21 program, Chonbuk National University, Jeonju 561-756, Korea
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18
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Kainic acid-induced neurodegenerative model: potentials and limitations. J Biomed Biotechnol 2010; 2011:457079. [PMID: 21127706 PMCID: PMC2992819 DOI: 10.1155/2011/457079] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 10/25/2010] [Indexed: 01/03/2023] Open
Abstract
Excitotoxicity is considered to be an important mechanism involved in various neurodegenerative diseases in the central nervous system (CNS) such as Alzheimer's disease (AD). However, the mechanism by which excitotoxicity is implicated in neurodegenerative disorders remains unclear. Kainic acid (KA) is an epileptogenic and neuroexcitotoxic agent by acting on specific kainate receptors (KARs) in the CNS. KA has been extensively used as a specific agonist for ionotrophic glutamate receptors (iGluRs), for example, KARs, to mimic glutamate excitotoxicity in neurodegenerative models as well as to distinguish other iGluRs such as α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors and N-methyl-D-aspartate receptors. Given the current knowledge of excitotoxicity in neurodegeneration, interventions targeted at modulating excitotoxicity are promising in terms of dealing with neurodegenerative disorders. This paper summarizes the up-to-date knowledge of neurodegenerative studies based on KA-induced animal model, with emphasis on its potentials and limitations.
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Park SA, Yin H, Bhattarai JP, Park SJ, Lee JC, Kim CJ, Han SK. Postnatal change of GluR5 kainate receptor expression in the substantia gelatinosa neuron of the trigeminal subnucleus caudalis in mice. Brain Res 2010; 1346:52-61. [PMID: 20513362 DOI: 10.1016/j.brainres.2010.05.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 05/20/2010] [Accepted: 05/23/2010] [Indexed: 10/19/2022]
Abstract
The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) has been implicated in the processing of nociceptive information from the orofacial region. Kainate receptors (KARs) play an important role in sensory transmission. Five different KAR subunits have been cloned and the expression of the KAR subunits showed developmental changes. In this study, RT-PCR, western blotting, immunohistochemistry and a patch clamp technique were used examine the functional expression of the GluR5 subunit in the SG of the Vc in juvenile, peripubertal and/or adult mice. The levels of mRNA and protein expression of the GluR5 subunit in the SG of the Vc were higher in the juvenile mice than in the peripubertal or adult mice. In addition, the KA and ATPA, a GluR5 KAR agonist, induced membrane depolarization on the SG neurons in both juvenile and adult mice in a concentration-dependent manner. However, the juvenile SG neurons showed a stronger response to KA and ATPA than those of adults. The membrane depolarization by KA was suppressed slightly in the presence of the AMPA receptor antagonist, GYKI 52466. These results show that the GluR5 KAR subunits are expressed functionally on the SG neurons of the Vc in mice, and the expression levels of the GluR5 subunits decrease with postnatal development. These postnatal changes in the GluR5 KAR subunit may be a possible mechanism for age-dependent pain processing.
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Affiliation(s)
- Seon Ah Park
- Department of Oral Physiology and BK21 program, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju, 561-756, Republic of Korea
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Larsson M, Broman J. Synaptic Plasticity and Pain: Role of Ionotropic Glutamate Receptors. Neuroscientist 2010; 17:256-73. [DOI: 10.1177/1073858409349913] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Pain hypersensitivity that develops after tissue or nerve injury is dependent both on peripheral processes in the affected tissue and on enhanced neuronal responses in the central nervous system, including the dorsal horn of the spinal cord. It has become increasingly clear that strengthening of glutamatergic sensory synapses, such as those established in the dorsal horn by nociceptive thin-caliber primary afferent fibers, is a major contributor to sensitization of neuronal responses that leads to pain hypersensitivity. Here, the authors review recent findings on the roles of ionotropic glutamate receptors in synaptic plasticity in the dorsal horn in relation to acute and persistent pain.
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Affiliation(s)
- Max Larsson
- Department of Anatomy and Centre for Molecular Biology and Neuroscience, University of Oslo, Oslo, Norway, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden,
| | - Jonas Broman
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Gregus AM, Inra CN, Giordano TP, Costa ACS, Rajadhyaksha AM, Inturrisi CE. Spinal mediators that may contribute selectively to antinociceptive tolerance but not other effects of morphine as revealed by deletion of GluR5. Neuroscience 2010; 169:475-87. [PMID: 20359526 DOI: 10.1016/j.neuroscience.2010.03.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 03/23/2010] [Accepted: 03/23/2010] [Indexed: 12/22/2022]
Abstract
Several groups maintain that morphine tolerance and dependence correlate with increased activity of protein kinases ERK1/2 and P38 MAPK and PKC as well as elevated levels of the neuropeptides dynorphin (DYN), substance P (sP), and calcitonin gene-related peptide (CGRP) in spinal cord dorsal horn (SCDH). They demonstrate that tolerance and dependence can be prevented, and sometimes reversed, by constitutive genetic deletion or pharmacological inhibition of these factors. Recently, we showed that mice with a constitutive deletion of the GluR5 subunit of kainate receptors (GluR5 KO) are not different from wild type (WT) littermates with respect to baseline nociceptive thresholds as well as acute morphine antinociception, morphine physical dependence and conditioned place preference. However, unlike WT, GluR5 KO mice do not develop antinociceptive tolerance following systemic morphine administration. In this report, we examined levels of these mediators in SCDH of WT and GluR5 KO mice following subcutaneous implantation of placebo or morphine pellets. Surprisingly, spinal DYN and CGRP, along with phosphorylated ERK2 (pERK2), P38 (pP38) and PKCgamma (pPKCgamma) are elevated by deletion of GluR5. Additionally, chronic systemic morphine administration increased spinal pERK2, pP38 and pPKCgamma levels in both tolerant WT and non-tolerant GluR5 KO mice. In contrast, while morphine increased spinal DYN and CGRP in WT mice, DYN remained unchanged and CGRP was reduced in GluR5 KO mice. These observations suggest that spinal ERK2, P38 and PKCgamma are likely involved in multiple adaptive responses following systemic morphine administration, whereas DYN and CGRP may contribute selectively to the development of antinociceptive tolerance.
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Affiliation(s)
- A M Gregus
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
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22
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In the developing rat hippocampus, endogenous activation of presynaptic kainate receptors reduces GABA release from mossy fiber terminals. J Neurosci 2010; 30:1750-9. [PMID: 20130184 DOI: 10.1523/jneurosci.4566-09.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Presynaptic kainate receptors regulate synaptic transmission in several brain areas but are not known to have this action at immature mossy fiber (MF) terminals, which during the first week of postnatal life release GABA, which exerts into targeted cells a depolarizing and excitatory action. Here, we report that, during the first week of postnatal life, endogenous activation of GluK1 receptors by glutamate present in the extracellular space severely depresses MF-mediated GABAergic currents [GABA(A)-mediated postsynaptic currents (GPSCs)]. Activation of GluK1 receptors was prevented by treating the slices with enzymatic glutamate scavengers that enhanced the clearance of glutamate from the extracellular space. The depressant effect of GluK1 on MF-GPSCs was mediated by a metabotropic process sensitive to pertussis toxin. In the presence of U73122 (1-[6-[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione), a selective inhibitor of phospholipase C, along the transduction pathway downstream to G-protein, GluK1 activation increased the probability of GABA release, thus unveiling the ionotropic action of this receptor. In line with this type of action, we found that GluK1 enhanced MF excitability by directly depolarizing MF terminals via calcium-permeable cation channels. Furthermore, GluK1 dynamically regulated the direction of spike time-dependent plasticity occurring by pairing MF stimulation with postsynaptic spiking and switched spike time-dependent potentiation into depression. The GluK1-induced depression of MF-GPSCs would prevent excessive activation of the CA3 associative network by the excitatory action of GABA and the emergence of seizures in the immature brain.
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Abstract
Presynaptic kainate receptors (KARs) exert a modulatory action on transmitter release. This effect can be switched from facilitation to inhibition by an increased concentration of KAR agonists. We here report that activation of presynaptic GluK1-containing KARs facilitates GABA release on oxytocin and vasopressin neurons in the supraoptic nucleus of the hypothalamus. Increase in ambient levels of glutamate associated with the physiological reduction of astrocytic coverage of oxytocin neurons in lactating rats switches this KAR-mediated facilitation to inhibition of GABAergic transmission. This effect was reproduced in both oxytocin and vasopressin neurons of virgin rats when glutamate transporters were blocked pharmacologically, thereby establishing that enhanced levels of extracellular glutamate induce the switch in KAR-mediated action. The facilitation of GABA release was inhibited with philanthotoxin, a Ca(2+)-permeable KAR antagonist, suggesting that this effect was associated with an ionotropic mode of action. Conversely, KAR-mediated inhibition was compromised in the presence of U73122, a phospholipase C inhibitor, in agreement with the involvement of a metabotropic pathway. We thus reveal that physiological astrocytic plasticity modifies the mode of action of presynaptic KARs, thereby inversing their coupling with GABA release.
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24
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Larsson M. Ionotropic glutamate receptors in spinal nociceptive processing. Mol Neurobiol 2009; 40:260-88. [PMID: 19876771 DOI: 10.1007/s12035-009-8086-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 09/29/2009] [Indexed: 02/07/2023]
Abstract
Glutamate is the predominant excitatory transmitter used by primary afferent synapses and intrinsic neurons in the spinal cord dorsal horn. Accordingly, ionotropic glutamate receptors mediate basal spinal transmission of sensory, including nociceptive, information that is relayed to supraspinal centers. However, it has become gradually more evident that these receptors are also crucially involved in short- and long-term plasticity of spinal nociceptive transmission, and that such plasticity have an important role in the pain hypersensitivity that may result from tissue or nerve injury. This review will cover recent findings on pre- and postsynaptic regulation of synaptic function by ionotropic glutamate receptors in the dorsal horn and how such mechanisms contribute to acute and chronic pain.
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Affiliation(s)
- Max Larsson
- Department of Anatomy and Centre for Molecular Biology and Neuroscience, University of Oslo, Norway.
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25
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Zhang WG, Zhang LC, Peng ZD, Zeng YM. Intrathecal injection of GluR6 antisense oligodeoxynucleotides alleviates acute inflammatory pain of rectum in rats. Neurosci Bull 2009; 25:319-23. [PMID: 19784088 PMCID: PMC5552604 DOI: 10.1007/s12264-009-0326-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVE To investigate whether the kainate (KA) receptor subunit GluR6 is involved in the acute inflammatory pain. METHODS Formalin was injected into the mucosa of rectum in Sprague-Dawley rats to induce visceral pain. The antisense oligodeoxynucleotides (ODNs) of GluR6 were injected once per day for 3 d before formalin injection, after which GluR6 protein level was examined by immunoblotting method. The change of visceral pain was also investigated. RESULTS The expression of GluR6 in the spinal cord of rats increased after the formalin injection. Moreover, pre-treatment of GluR6 antisense ODNs could suppress GluR6 expression in the spinal cord of rats and decrease the scores of visceral pain at 45 min following formalin injection. CONCLUSION Kainate receptor subunit GluR6 plays an important role in the visceral pain induced by injection of formalin into the wall of rectum. GluR6 may serve as a potential target for the treatment of acute inflammatory visceral pain.
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Affiliation(s)
- Wei-Guang Zhang
- Key Laboratory of Anesthesiology of Jiangsu Province, Xuzhou Medical College, Xuzhou 221002, China.
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26
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Youn DH, Wang H, Jeong SJ. Exogenous tumor necrosis factor-alpha rapidly alters synaptic and sensory transmission in the adult rat spinal cord dorsal horn. J Neurosci Res 2008; 86:2867-75. [PMID: 18543334 DOI: 10.1002/jnr.21726] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) is involved in the generation of inflammatory and neuropathic pain. This study investigated if TNF-alpha has any effect on spinal synaptic and/or sensory transmission by using whole-cell recordings of substantia gelatinosa (SG) neurons in transverse lumbar spinal cord slices of adult rats and by using behavioral tests. After intrathecal administration of TNF-alpha in adult rats, spontaneous hind paw withdrawal behavior and thermal hyperalgesia were rapidly induced (approximately 30 min), while mechanical allodynia slowly developed. Bath application of TNF-alpha (0.1-1 nM, 8 min) depressed peak amplitude of monosynaptic Adelta and C fiber-evoked excitatory postsynaptic currents (EPSCs) without changing in holding currents and input resistances, whereas this application generally potentiated polysynaptic Adelta fiber-evoked EPSCs. Moreover, the frequencies, but not the amplitudes, of spontaneous and miniature EPSCs and spontaneous inhibitory postsynaptic currents were significantly increased by bath-applied TNF-alpha in most of the SG neurons. The effects of TNF-alpha on Adelta/C fiber-evoked monosynaptic and polysynaptic or spontaneous EPSCs were significantly blocked by 5 microM TNF-alpha antagonist that inhibits TNF-alpha binding to its type 1 receptor (TNFR1). Because this study also found high protein expression of TNFR1 in the adult dorsal root ganglion and no change of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) induced whole-cell currents by TNF-alpha, we conclude that presynaptic TNFR1 at Adelta/C primary afferent terminals contributes to the rapid alteration of synaptic transmission in the spinal SG, and the development of abnormal pain hypersensitivity by exogenous TNF-alpha.
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Affiliation(s)
- Dong-Ho Youn
- Department of Anesthesia and Critical Care, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA.
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27
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Galik J, Youn DH, Kolaj M, Randić M. Involvement of group I metabotropic glutamate receptors and glutamate transporters in the slow excitatory synaptic transmission in the spinal cord dorsal horn. Neuroscience 2008; 154:1372-87. [DOI: 10.1016/j.neuroscience.2008.04.059] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/24/2008] [Accepted: 04/27/2008] [Indexed: 01/17/2023]
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28
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Youn DH, Royle G, Kolaj M, Vissel B, Randić M. Enhanced LTP of primary afferent neurotransmission in AMPA receptor GluR2-deficient mice. Pain 2007; 136:158-67. [PMID: 17826911 DOI: 10.1016/j.pain.2007.07.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2006] [Revised: 06/29/2007] [Accepted: 07/09/2007] [Indexed: 11/26/2022]
Abstract
Ca(2+)-permeable-AMPA receptors (AMPARs) are expressed in the superficial dorsal horn (SDH, laminae I/II) of the spinal cord, the area involved in transmission and modulation of sensory information, including nociception. A possible role of Ca(2+)-permeable-AMPARs in synaptic strengthening has been suggested in postnatal DH cultures, but their role in the long-lasting activity-dependent synaptic plasticity of primary afferent neurotransmission in the adult mouse SDH has not been investigated. In the present study the role of Ca(2+)-permeable-AMPARs in the regulation of long-lasting synaptic plasticity, specifically long-term potentiation (LTP) and long-term depression (LTD) in the SDH, was investigated using mice deficient in AMPAR GluR2 subunit. We show here that the GluR2 mutants exhibited no changes in passive membrane properties, but a significant increase in rectification of excitatory postsynaptic currents, the finding suggesting increased expression of Ca(2+)-permeable-AMPARs. In the absence of GluR2, high-frequency stimulation (HFS) of small-diameter primary afferent fibers induced LTP that is enhanced and non-saturating in the SDH at both primary afferent Adelta- and/or C-fibers monosynaptic and polysynaptic pathways, whereas neuronal excitability and paired-pulse depression were normal. The LTP could be induced in the presence of the NMDA receptor antagonist d-AP5, and L-type Ca(2+) channel blockers, suggesting that Ca(2+)-permeable-AMPARs are sufficient to induce LTP in the SDH neurons of adult mouse spinal cord. In contrast, the induction of HFS-LTD is reduced in the SDH of GluR2 mutants. These results suggest an important role for AMPAR GluR2 subunit in regulating synaptic plasticity with potential relevance for long-lasting hypersensitivity in pathological states.
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Affiliation(s)
- Dong-Ho Youn
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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29
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Wu LJ, Xu H, Ren M, Zhuo M. Genetic and pharmacological studies of GluR5 modulation of inhibitory synaptic transmission in the anterior cingulate cortex of adult mice. Dev Neurobiol 2007; 67:146-57. [PMID: 17443779 DOI: 10.1002/dneu.20331] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the anterior cingulate cortex (ACC), GluR5-containing kainate receptor mediated the small portion of excitatory postsynaptic current. However, little is known about its role in modulation of neurotransmitter release in this brain region. In the present study, we address this question by using selective GluR5 agonist and antagonist, as well as GluR5(-/-) mice. Our results showed that activation of GluR5 induced action potential-dependent GABA release, which is also required for the activation of voltage-dependent calcium channel and Ca(2+) influx. The effect of GluR5 activation is selective to the GABAergic, but not glutamatergic synaptic transmission. Endogenous activation of GluR5 also enhanced GABA release to ACC pyramidal neurons and the corresponding postsynaptic tonic GABA current. Our results suggest the somatodendritic, but not presynaptic GluR5, in modulation of GABA release. The endogenous GluR5 activation and the subsequent tonic GABA current may play an inhibitory role in ACC-related brain functions.
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Affiliation(s)
- Long-Jun Wu
- Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, Toronto, Ontario, Canada M5S 1A8
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30
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Santos SFA, Rebelo S, Derkach VA, Safronov BV. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat. J Physiol 2007; 581:241-54. [PMID: 17331995 PMCID: PMC2075233 DOI: 10.1113/jphysiol.2006.126912] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Substantia gelatinosa (SG, lamina II) is a spinal cord region where most unmyelinated primary afferents terminate and the central nociceptive processing begins. It is formed by several distinct groups of interneurons whose functional properties and synaptic connections are poorly understood, in part, because recordings from synaptically coupled pairs of SG neurons are quite challenging due to a very low probability of finding connected cells. Here, we describe an efficient method for identifying synaptically coupled interneurons in rat spinal cord slices and characterizing their excitatory or inhibitory function. Using tight-seal whole-cell recordings and a cell-attached stimulation technique, we routinely tested about 1500 SG interneurons, classifying 102 of them as monosynaptically connected to neurons in lamina I-III. Surprisingly, the vast majority of SG interneurons (n = 87) were excitatory and glutamatergic, while only 15 neurons were inhibitory. According to their intrinsic firing properties, these 102 SG neurons were also classified as tonic (n = 49), adapting (n = 17) or delayed-firing neurons (n = 36). All but two tonic neurons and all adapting neurons were excitatory interneurons. Of 36 delayed-firing neurons, 23 were excitatory and 13 were inhibitory. We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding.
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Affiliation(s)
- Sónia F A Santos
- Instituto de Biologia Molecular e Celular-IBMC, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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Abstract
Glutamate acts through a variety of receptors to modulate neurotransmission and neuronal excitability. Glutamate plays a critical role in neuroplasticity as well as in nervous system dysfunctions and disorders. Hyperfunction or dysfunction of glutamatergic neurotransmission also represents a key mechanism of pain-related plastic changes in the central and peripheral nervous system. This chapter will review the classification of glutamate receptors and their role in peripheral and central nociceptive processing. Evidence from preclinical pain models and clinical studies for the therapeutic value of certain glutamate receptor ligands will be discussed.
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Affiliation(s)
- V Neugebauer
- Department of Neuroscience and Cell Biology, The University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1069, USA.
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32
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Abstract
Pain is an important survival and protection mechanism for animals. However, chronic/persistent pain may be differentiated from normal physiological pain in that it confers no obvious advantage. An accumulating body of pharmacological, electrophysiological, and behavioral evidence is emerging in support of the notion that glutamate receptors play a crucial role in pain pathways and that modulation of glutamate receptors may have potential for therapeutic utility in several categories of persistent pain, including neuropathic pain resulting from injury and/or disease of central (e.g., spinal cord injury) or peripheral nerves (e.g., diabetic neuropathy, radiculopathy) and inflammatory or joint-related pain (e.g., rheumatoid arthritis, osteoarthritis). This review focuses on the role of glutamate receptors, including both ionotropic (AMPA, NMDA and kainate) and metabotropic (mGlu1-8) receptors in persistent pain states with particular emphasis on their expression patterns in nociceptive pathways and their potential as targets for pharmacological intervention strategies.
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Affiliation(s)
- David Bleakman
- Neuroscience Division, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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33
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Xu H, Wu LJ, Zhao MG, Toyoda H, Vadakkan KI, Jia Y, Pinaud R, Zhuo M. Presynaptic regulation of the inhibitory transmission by GluR5-containing kainate receptors in spinal substantia gelatinosa. Mol Pain 2006; 2:29. [PMID: 16948848 PMCID: PMC1570342 DOI: 10.1186/1744-8069-2-29] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Accepted: 09/01/2006] [Indexed: 11/29/2022] Open
Abstract
GluR5-containing kainate receptors (KARs) are known to be involved in nociceptive transmission. Our previous work has shown that the activation of presynaptic KARs regulates GABAergic and glycinergic synaptic transmission in cultured dorsal horn neurons. However, the role of GluR5-containing KARs in the modulation of inhibitory transmission in the spinal substantia gelatinosa (SG) in slices remains unknown. In the present study, pharmacological, electrophysiological and genetic methods were used to show that presynaptic GluR5 KARs are involved in the modulation of inhibitory transmission in the SG of spinal slices in vitro. The GluR5 selective agonist, ATPA, facilitated the frequency but not amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) in SG neurons. ATPA increased sIPSC frequency in all neurons with different firing patterns as delayed, tonic, initial and single spike patterns. The frequency of either GABAergic or glycinergic sIPSCs was significantly increased by ATPA. ATPA could also induce inward currents in all SG neurons recorded. The frequency, but not amplitude, of action potential-independent miniature IPSCs (mIPSCs) was also facilitated by ATPA in a concentration-dependent manner. However, the effect of ATPA on the frequency of either sIPSCs or mIPSCs was abolished in GluR5-/- mice. Deletion of the GluR5 subunit gene had no effect on the frequency or amplitude of mIPSCs in SG neurons. However, GluR5 antagonist LY293558 reversibly inhibited sIPSC and mIPSC frequencies in spinal SG neurons. Taken together, these results suggest that GluR5 KARs, which may be located at presynaptic terminals, contribute to the modulation of inhibitory transmission in the SG. GluR5-containing KARs are thus important for spinal sensory transmission/modulation in the spinal cord.
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Affiliation(s)
- Hui Xu
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Long-Jun Wu
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Ming-Gao Zhao
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Hiroki Toyoda
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Kunjumon I Vadakkan
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Yongheng Jia
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Raphael Pinaud
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Min Zhuo
- Department of Physiology, Faculty of Medicine, University of Toronto, University of Toronto Centre for the Study of Pain, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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34
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Abstract
Kainate receptors form a family of ionotropic glutamate receptors that appear to play a special role in the regulation of the activity of synaptic networks. This review first describes briefly the molecular and pharmacological properties of native and recombinant kainate receptors. It then attempts to outline the general principles that appear to govern the function of kainate receptors in the activity of synaptic networks under physiological conditions. It subsequently describes the way that kainate receptors are involved in synaptic integration, synaptic plasticity, the regulation of neurotransmitter release and the control of neuronal excitability, and the manner in which they might play an important role in synaptogenesis and synaptic maturation. These functions require the proper subcellular localization of kainate receptors in specific functional domains of the neuron, necessitating complex cellular and molecular trafficking events. We show that our comprehension of these mechanisms is just starting to emerge. Finally, this review presents evidence that implicates kainate receptors in pathophysiological conditions such as epilepsy, excitotoxicity and pain, and that shows that these receptors represent promising therapeutic targets.
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Affiliation(s)
- Paulo Pinheiro
- CNRS UMR 5091, Laboratoire "Physiologie Cellulaire de la Synapse", Bordeaux Neuroscience Institute, University of Bordeaux, 33077 Bordeaux Cedex, France
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Alt A, Weiss B, Ogden AM, Li X, Gleason SD, Calligaro DO, Bleakman D, Witkin JM. In vitro and in vivo studies in rats with LY293558 suggest AMPA/kainate receptor blockade as a novel potential mechanism for the therapeutic treatment of anxiety disorders. Psychopharmacology (Berl) 2006; 185:240-7. [PMID: 16470401 DOI: 10.1007/s00213-005-0292-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Accepted: 12/06/2005] [Indexed: 11/26/2022]
Abstract
RATIONALE Although convergent evidence exists for a role of glutamate in the regulation of anxiety, the involvement of specific glutamate receptor subtypes has yet to be defined. OBJECTIVE To evaluate the potential for blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors to produce anxioltyic-like effects with the AMPA/GLU(K5) (kainate) antagonist (3S,4aR,6R,8aR)-6-[2-(1(2)H-tetrazole-5yl)ethyl]decahydroisoquinoline-3carboxylic acid (LY293558) MATERIALS AND METHODS Punished responding of rats was used to determine the efficacy of LY293558. Other in vivo and in vitro studies further characterized the specificity of LY293558 for AMPA/kainate receptors. RESULTS LY293558 had a rank order of potency of GLU(K5) > or = GLU(K5/6) approximately GLU(A2i) approximately GLU(K2/5) approximately GLU(A1i) approximately GLU(A2o) approximately GLU(A3i) approximately GLU(A1o) > or = GLU(A3o) > or = GLU(A4i) approximately GLU(A4o) and >100 microM affinity for rat cortical GABA(A) receptors. Comparison of the blockade of AMPA- vs N-methyl-D-aspartate (NMDA)-induced inward currents demonstrated that LY293558 was five-fold more potent as an antagonist at AMPA vs NMDA receptors in vitro. In keeping with the low affinity of LY293558 for NMDA receptors, LY293558 was not effective in preventing NMDA-induced seizures in mice. LY293558 increased punished responding, a preclinical predictor of anxiolytic efficacy, at a dose that decreased unpunished responding (10 mg/kg, i.p.). Chlordiazepoxide produced comparable increases in both punished and unpunished responding. The NMDA antagonist dizocilpine [(+)-MK-801] also increased both punished and unpunished responding. CONCLUSIONS These data along with those in the literature suggest that AMPA and/or kainate receptor blockade may be an important component to producing anxiolytic-like effects and may therefore be a target for compounds with efficacy in the therapeutic treatment of anxiety disorders.
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Affiliation(s)
- Andrew Alt
- Neuroscience Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Lucifora S, Willcockson HH, Lu CR, Darstein M, Phend KD, Valtschanoff JG, Rustioni A. Presynaptic low- and high-affinity kainate receptors in nociceptive spinal afferents. Pain 2006; 120:97-105. [PMID: 16360275 DOI: 10.1016/j.pain.2005.10.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 09/26/2005] [Accepted: 10/19/2005] [Indexed: 10/25/2022]
Abstract
Presynaptic ionotropic glutamate receptors are increasingly attributed a role in the modulation of sensory input at the first synapse of dorsal root ganglion (DRG) neurons in the spinal dorsal horn. Central terminals of DRG neurons express AMPA and NMDA receptors whose activation modulates the release of glutamate, the main transmitter at these synapses. Previous work, with an antibody that recognizes all low-affinity kainate receptor subunits (GluR5, 6, 7), provided microscopic evidence of presynaptic kainate receptors in unidentified primary afferent terminals in superficial laminae of the spinal dorsal horn (Hwang SJ, Pagliardini S, Rustioni A, Valtschanoff JG. Presynaptic kainate receptors in primary afferents to the superficial laminae of the rat spinal cord. J Comp Neurol 2001; 436: pp. 275-289). We show here that, although all such subunits may be expressed in these terminals, GluR5 is the subunit most readily detectable at presynaptic sites in sections processed for immunocytochemistry. We also show that the high-affinity kainate receptor subunits KA1 and KA2 are expressed in central terminals of DRG neurons and are co-expressed with low-affinity receptor subunits in the same terminals. Quantitative data show that kainate-expressing DRG neurons are about six times more likely to express the P2X(3) subunit of the purinergic receptor than to express substance P. Thus, nociceptive afferents that express presynaptic kainate receptors are predominantly non-peptidergic, suggesting a role for these receptors in the modulation of neuropathic rather than inflammatory pain.
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Affiliation(s)
- Simona Lucifora
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA Department of Physiological Sciences, University of Catania, Italy Institute of Anatomy and Cell Biology I, University of Freiburg, Albertstrasse 17, D-79104 Freiburg, Germany
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Youn DH, Voitenko N, Gerber G, Park YK, Galik J, Randić M. Altered long-term synaptic plasticity and kainate-induced Ca2+ transients in the substantia gelatinosa neurons in GLUK6-deficient mice. ACTA ACUST UNITED AC 2005; 142:9-18. [PMID: 16219388 DOI: 10.1016/j.molbrainres.2005.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 08/24/2005] [Accepted: 09/05/2005] [Indexed: 11/22/2022]
Abstract
Functional kainate receptors are expressed in the spinal cord substantia gelatinosa region, and their activation contributes to bi-directional regulation of excitatory synaptic transmission at primary afferent synapses with spinal cord substantia gelatinosa neurons. However, no study has reported a role(s) for kainate receptor subtypes in long-term synaptic plasticity phenomena in this region. Using gene-targeted mice lacking glutamate receptor 5 (GLU(K5)) or GLU(K6) subunit, we here show that GLU(K6) subunit, but not GLU(K5) subunit, is involved in the induction of long-term potentiation of excitatory postsynaptic potentials, evoked by two different protocols: (1) high-frequency primary afferent stimulation (100 Hz, 3 s) and (2) low-frequency spike-timing stimulation (1 Hz, 200 pulses). In addition, GLU(K6) subunit plays an important role in the expression of kainate-induced Ca2+ transients in the substantia gelatinosa. On the other hand, genetic deletion of GLU(K5) or GLU(K6) subunit does not prevent the induction of long-term depression. These results indicate that unique expression of kainate receptors subunits is important in regulating spinal synaptic plasticity and thereby processing of sensory information, including pain.
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Affiliation(s)
- Dong-Ho Youn
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
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Dahlhaus A, Ruscheweyh R, Sandkühler J. Synaptic input of rat spinal lamina I projection and unidentified neurones in vitro. J Physiol 2005; 566:355-68. [PMID: 15878938 PMCID: PMC1464766 DOI: 10.1113/jphysiol.2005.088567] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Spinal lamina I projection neurones that transmit nociceptive information to the brain play a pivotal role in hyperalgesia in various animal models of inflammatory and neuropathic pain. Consistently, activity-dependent long-term potentiation can be induced at synapses between primary afferent C-fibres and lamina I projection neurones but not unidentified neurones in lamina I. The specific properties that enable projection neurones to undergo long-term potentiation and mediate hyperalgesia are not fully understood. Here, we have tested whether lamina I projection neurones differ from unidentified neurones in types or strength of primary afferent input and/or action potential-independent excitatory and inhibitory input. We used the whole-cell patch-clamp technique to record synaptic currents in projection and unidentified lamina I neurones in a transverse lumbar spinal cord slice preparation from rats between postnatal day 18 and 37. Lamina I neurones with a projection to the parabrachial area or the periaqueductal grey were identified by retrograde labelling with a fluorescent tracer. The relative contribution of NMDA receptors versus AMPA/kainate receptors to C-fibre-evoked excitatory postsynaptic currents of lamina I neurones significantly decreased with age between postnatal day 18 and 27, but was independent of the supraspinal projection of the neurones. We did not find a significant contribution of kainate receptors to C-fibre-evoked excitatory postsynaptic currents. Lamina I projection and unidentified neurones possessed functional GABAA and glycine receptors but received scarce action potential-independent spontaneous GABAergic and glycinergic inhibitory input as measured by miniature inhibitory postsynaptic currents. The miniature excitatory postsynaptic current frequencies were five times higher in projection than in unidentified neurones. The predominance of excitatory synaptic input to projection neurones, taken together with the previous finding that their membranes are more easily excitable than those of unidentified neurones, may facilitate the induction of synaptic long-term potentiation.
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Affiliation(s)
- Anne Dahlhaus
- Center for Brain Research, Department of Neurophysiology, Medical University of Vienna, Vienna, Austria
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Ko S, Zhao MG, Toyoda H, Qiu CS, Zhuo M. Altered behavioral responses to noxious stimuli and fear in glutamate receptor 5 (GluR5)- or GluR6-deficient mice. J Neurosci 2005; 25:977-84. [PMID: 15673679 PMCID: PMC6725621 DOI: 10.1523/jneurosci.4059-04.2005] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2004] [Revised: 11/23/2004] [Accepted: 12/13/2004] [Indexed: 11/21/2022] Open
Abstract
Different kainate receptor (KAR) subtypes contribute to the regulation of both excitatory and inhibitory transmission. However, no study has reported a role for KAR subtypes in behavioral responses to persistent pain and fear memory. Here we show that responses to capsaicin or inflammatory pain were significantly reduced in mice lacking glutamate receptor 5 (GluR5) but not GluR6 subunits. In classic fear-memory tests, mice lacking GluR6 but not GluR5 showed a significant reduction in fear memory when measured 3, 7, or 14 d after training. Additionally, synaptic potentiation was significantly reduced in the lateral amygdala of GluR6 but not GluR5 knock-out mice. Our findings provide evidence that distinct KAR subtypes contribute to chemical/inflammatory pain and fear memory. Selectively targeting different KAR subtypes may provide a useful strategy for treating persistent pain and fear-related mental disorders.
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Affiliation(s)
- Shanelle Ko
- Department of Physiology, Faculty of Medicine, and Centre for the Study of Pain, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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