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Jang K, Garraway SM. A review of dorsal root ganglia and primary sensory neuron plasticity mediating inflammatory and chronic neuropathic pain. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2024; 15:100151. [PMID: 38314104 PMCID: PMC10837099 DOI: 10.1016/j.ynpai.2024.100151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/04/2024] [Accepted: 01/19/2024] [Indexed: 02/06/2024]
Abstract
Pain is a sensory state resulting from complex integration of peripheral nociceptive inputs and central processing. Pain consists of adaptive pain that is acute and beneficial for healing and maladaptive pain that is often persistent and pathological. Pain is indeed heterogeneous, and can be expressed as nociceptive, inflammatory, or neuropathic in nature. Neuropathic pain is an example of maladaptive pain that occurs after spinal cord injury (SCI), which triggers a wide range of neural plasticity. The nociceptive processing that underlies pain hypersensitivity is well-studied in the spinal cord. However, recent investigations show maladaptive plasticity that leads to pain, including neuropathic pain after SCI, also exists at peripheral sites, such as the dorsal root ganglia (DRG), which contains the cell bodies of sensory neurons. This review discusses the important role DRGs play in nociceptive processing that underlies inflammatory and neuropathic pain. Specifically, it highlights nociceptor hyperexcitability as critical to increased pain states. Furthermore, it reviews prior literature on glutamate and glutamate receptors, voltage-gated sodium channels (VGSC), and brain-derived neurotrophic factor (BDNF) signaling in the DRG as important contributors to inflammatory and neuropathic pain. We previously reviewed BDNF's role as a bidirectional neuromodulator of spinal plasticity. Here, we shift focus to the periphery and discuss BDNF-TrkB expression on nociceptors, non-nociceptor sensory neurons, and non-neuronal cells in the periphery as a potential contributor to induction and persistence of pain after SCI. Overall, this review presents a comprehensive evaluation of large bodies of work that individually focus on pain, DRG, BDNF, and SCI, to understand their interaction in nociceptive processing.
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Affiliation(s)
- Kyeongran Jang
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
| | - Sandra M. Garraway
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, 30322, USA
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2
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Lu L, Mei L, Li X, Lin Y, Wang H, Yang G. Metabolomics profiling in predicting of post-herpetic neuralgia induced by varicella zoster. Sci Rep 2023; 13:14940. [PMID: 37697028 PMCID: PMC10495364 DOI: 10.1038/s41598-023-42363-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 09/09/2023] [Indexed: 09/13/2023] Open
Abstract
To explore potential metabolomics biomarkers in predicting post-herpetic neuralgia (PHN) induced by herpes zoster (HZ). A total of 90 eligible patients were prospectively enrolled and assigned into an acute pain (ACP) group and a PHN group. Serum samples were collected before clinical intervention to perform metabolomics profiling analyses using gas chromatography mass spectrometry (GC-MS). Key metabolites were identified using partial least squares discriminant analysis (PLS-DA). A binary logistic regression was used to build a combined biomarker model to predict PHN from ACP. The discriminating efficiency of the combined biomarker model was investigated and validated by internal validation. Six metabolites were identified as the key metabolites related to PHN. All these metabolites (N-Acetyl-5-hydroxytryptaMine, glucose, dehydroascorbic acid, isopropyl-beta-D-thiogalactopyranoside, 1,5-anhydro-D-sorbitol, and glutamic acid) were found elevated in the PHN group. Pathway analyses showed that glucose-alanine cycle, tryptophan metabolism, tyrosine metabolism, lactose degradation, malate-aspartate shuttle were top five metabolic pathways evolved in PHN. The AUC was 0.85 (95% CI 0.76-0.93) for the combined biomarker model, and was 0.91 (95% CI 0.84-1.00) for the internal validation data set to predict PHN. Metabolomics analyses of key metabolites could be used to predict PHN induced by HZ.
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Affiliation(s)
- Lina Lu
- Department of Dermatology, Jinshan Hospital, Fudan University, Shanghai, 201508, China
| | - Lihong Mei
- Department of Dermatology, Jinshan Hospital, Fudan University, Shanghai, 201508, China
| | - Xushuo Li
- Department of Center for Tumor Diagnosis & Therapy, Jinshan Hospital, Fudan University, Shanghai, 201508, China
| | - Yanhua Lin
- Department of Clinical Laboratory, Jinshan Hospital, Fudan University, Shanghai, 201508, China
| | - Hongfeng Wang
- Department of Dermatology, Jinshan Hospital, Fudan University, Shanghai, 201508, China
| | - Gao Yang
- Department of Dermatology, Jinshan Hospital, Fudan University, Shanghai, 201508, China.
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3
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Temmermand R, Barrett JE, Fontana ACK. Glutamatergic systems in neuropathic pain and emerging non-opioid therapies. Pharmacol Res 2022; 185:106492. [PMID: 36228868 PMCID: PMC10413816 DOI: 10.1016/j.phrs.2022.106492] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 01/14/2023]
Abstract
Neuropathic pain, a disease of the somatosensory nervous system, afflicts many individuals and adequate management with current pharmacotherapies remains elusive. The glutamatergic system of neurons, receptors and transporters are intimately involved in pain but, to date, there have been few drugs developed that therapeutically modulate this system. Glutamate transporters, or excitatory amino acid transporters (EAATs), remove excess glutamate around pain transmitting neurons to decrease nociception suggesting that the modulation of glutamate transporters may represent a novel approach to the treatment of pain. This review highlights and summarizes (1) the physiology of the glutamatergic system in neuropathic pain, (2) the preclinical evidence for dysregulation of glutamate transport in animal pain models, and (3) emerging novel therapies that modulate glutamate transporters. Successful drug discovery requires continuous focus on basic and translational methods to fully elucidate the etiologies of this disease to enable the development of targeted therapies. Increasing the efficacy of astrocytic EAATs may serve as a new way to successfully treat those suffering from this devastating disease.
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Affiliation(s)
- Rhea Temmermand
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
| | - James E Barrett
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Andréia C K Fontana
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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4
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Durán AM, Beeson WL, Firek A, Cordero-MacIntyre Z, De León M. Dietary Omega-3 Polyunsaturated Fatty-Acid Supplementation Upregulates Protective Cellular Pathways in Patients with Type 2 Diabetes Exhibiting Improvement in Painful Diabetic Neuropathy. Nutrients 2022; 14:nu14040761. [PMID: 35215418 PMCID: PMC8876723 DOI: 10.3390/nu14040761] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/04/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022] Open
Abstract
Background: Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to improve chronic neuroinflammatory diseases in peripheral and central nervous systems. For instance, docosahexaenoic acid (DHA) protects nerve cells from noxious stimuli in vitro and in vivo. Recent reports link PUFA supplementation to improving painful diabetic neuropathy (pDN) symptoms, but cellular mechanisms responsible for this therapeutic effect are not well understood. The objective of this study is to identify distinct cellular pathways elicited by dietary omega-3 PUFA supplementation in patients with type 2 diabetes mellitus (T2DM) affected by pDN. Methods: Forty volunteers diagnosed with type 2 diabetes were enrolled in the “En Balance-PLUS” diabetes education study. The volunteers participated in weekly lifestyle/nutrition education and daily supplementation with 1000 mg DHA and 200 mg eicosapentaenoic acid. The Short-Form McGill Pain Questionnaire validated clinical determination of baseline and post-intervention pain complaints. Laboratory and untargeted metabolomics analyses were conducted using blood plasma collected at baseline and after three months of participation in the dietary regimen. The metabolomics data were analyzed using random forest, hierarchical clustering, ingenuity pathway analysis, and metabolic pathway mapping. Results: The data show that metabolites involved in oxidative stress and glutathione production shifted significantly to a more anti-inflammatory state post supplementation. Example of these metabolites include cystathionine (+90%), S-methylmethionine (+9%), glycine cysteine-glutathione disulfide (+157%) cysteinylglycine (+19%), glutamate (−11%), glycine (+11%), and arginine (+13.4%). In addition, the levels of phospholipids associated with improved membrane fluidity such as linoleoyl-docosahexaenoyl-glycerol (18:2/22:6) (+253%) were significantly increased. Ingenuity pathway analysis suggested several key bio functions associated with omega-3 PUFA supplementation such as formation of reactive oxygen species (p = 4.38 × 10−4, z-score = −1.96), peroxidation of lipids (p = 2.24 × 10−5, z-score = −1.944), Ca2+ transport (p = 1.55 × 10−4, z-score = −1.969), excitation of neurons (p = 1.07 ×10−4, z-score = −1.091), and concentration of glutathione (p = 3.06 × 10−4, z-score = 1.974). Conclusion: The reduction of pro-inflammatory and oxidative stress pathways following dietary omega-3 PUFA supplementation is consistent with the promising role of these fatty acids in reducing adverse symptoms associated with neuroinflammatory diseases and painful neuropathy.
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Affiliation(s)
- Alfonso M. Durán
- Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (A.M.D.); (W.L.B.); (Z.C.-M.)
| | - W. Lawrence Beeson
- Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (A.M.D.); (W.L.B.); (Z.C.-M.)
- Center for Nutrition, Healthy Lifestyle and Disease Prevention, School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA
| | - Anthony Firek
- Comparative Effectiveness and Clinical Outcomes Research Center, Riverside University Health System Medical Center, Moreno Valley, CA 92555, USA;
| | - Zaida Cordero-MacIntyre
- Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (A.M.D.); (W.L.B.); (Z.C.-M.)
- Center for Nutrition, Healthy Lifestyle and Disease Prevention, School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA
| | - Marino De León
- Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA; (A.M.D.); (W.L.B.); (Z.C.-M.)
- Correspondence: ; Tel.: +1-909-558-9474
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Su L, Bai X, Niu T, Zhuang X, Dong B, Wang G, Yu Y. P2Y1 purinergic receptor inhibition attenuated remifentanil-induced postoperative hyperalgesia via decreasing NMDA receptor phosphorylation in dorsal root ganglion. Brain Res Bull 2021; 177:352-362. [PMID: 34653560 DOI: 10.1016/j.brainresbull.2021.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 12/22/2022]
Abstract
BACKGROUND Remifentanil-induced postoperative hyperalgesia is an intractable side effect of the clinical use of remifentanil, the mechanism of which remains obscure, especially in the peripheral nervous system. N-methyl-D-aspartate receptor (NMDAR) phosphorylation in dorsal root ganglion (DRG) plays a pronociceptive role in neuropathic pain. The contribution of the P2Y1 purinergic receptor (P2Y1R) in DRG to pain hypersensitivity derived from various origins and P2Y1R upregulation-induced NMDAR activation in neurons have also been uncovered. This study aimed to investigate whether P2Y1R participates in nociceptive processing in the DRG and spinal cord in remifentanil-induced postoperative hyperalgesia. METHODS Rats with remifentanil-induced postoperative hyperalgesia were intrathecally injected with NMDAR antagonist MK801 or P2Y1R antagonist MRS2179 at 10 min prior to remifentanil infusion. Mechanical allodynia, heat hyperalgesia, and cold hyperalgesia were measured at -24 h, 2 h, 6 h, 24 h, and 48 h following remifentanil infusion. The P2Y1R expression and NMDAR expression and phosphorylation in DRG ipsilateral to the incision were detected by Western blot and immunofluorescence. RESULTS Incision and remifentanil induced mechanical allodynia, heat hyperalgesia, and cold hyperalgesia accompanied by upregulated P2Y1R expression, increased NMDAR subunit NR1 expression and phosphorylation at Ser896, and NR2B expression and phosphorylation at Tyr1472 in DRG. Inhibition of NMDAR phosphorylation by MK801 effectively attenuated remifentanil-induced postoperative hyperalgesia. Furthermore, P2Y1R blockade by MRS2179 not only lessened remifentanil-evoked postoperative hypersensitivity to mechanical, heat, and cold stimuli, but also suppressed the increases in NR1 and NR2B expression and phosphorylation in DRG induced by incision and remifentanil. CONCLUSION The process by which P2Y1R mediates NMDAR expression and phosphorylation represents a mechanism of remifentanil-induced postoperative hyperalgesia in the DRG and/or spinal cord.
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Affiliation(s)
- Lin Su
- Department of Anesthesiology, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Xiaoqing Bai
- Department of Science and Education, Tianjin Beichen Hospital, No. 7 Beiyi Road, Beichen District, Tianjin 300400, PR China
| | - Tongxiang Niu
- Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Department of Anesthesiology, Tianjin Jinnan Hospital, No. 120 Jingu Road, Jinnan District, Tianjin 300350, PR China
| | - Xinqi Zhuang
- Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Department of Anesthesiology, Tianjin Medical University Second Hospital, No. 23 Pingjiang Road, Hexi District, Tianjin 300211, PR China
| | - Beibei Dong
- Department of Anesthesiology, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Guolin Wang
- Department of Anesthesiology, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China
| | - Yonghao Yu
- Department of Anesthesiology, Tianjin Medical University General Hospital, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China; Tianjin Research Institute of Anesthesiology, No. 154 Anshan Road, Heping District, Tianjin 300052, PR China.
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6
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Controlling the "Opioid Epidemic": A Novel Chemical Entity (NCE) to Reduce or Supplant Opiate Use for Chronic Pain. ACTA ACUST UNITED AC 2020; 5. [PMID: 33117893 PMCID: PMC7591148 DOI: 10.20900/jpbs.20200022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We report on the ongoing project “A Novel Therapeutic to Ameliorate Chronic Pain and Reduce Opiate Use.” Over 100 million adults in the U.S. suffer from intermittent or constant chronic pain, and chronic pain affects at least 10% of the world’s population. The primary pharmaceuticals for treatment of chronic pain have been natural or synthetic opioids and the use of opioids for pain treatment has resulted in what has been called an “epidemic” of opioid abuse, addiction and lethal overdoses. We have, through a process of rational drug design, generated a novel chemical entity (NCE) and have given it the name Kindolor. Kindolor is a non-opiate, non-addicting molecule that was developed specifically to simultaneously control the aberrant activity of three targets on the peripheral sensory system that are integral in the development and propagation of chronic pain. In our initial preclinical studies, we demonstrated the efficacy of Kindolor to reduce or eliminate chronic pain in five animal models. The overall goal of the project is to complete the investigational new drug (IND)-enabling preclinical studies of Kindolor, and once IND approval is gained, we will proceed to the clinical Phase Ia and 1b safety studies and a Phase 2a efficacy study. The work is in its second year, and the present report describes progress toward our overall goal of bringing our compound to a full Phase 2 ready stage.
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Teckchandani S, Nagana Gowda GA, Raftery D, Curatolo M. Metabolomics in chronic pain research. Eur J Pain 2020; 25:313-326. [PMID: 33065770 DOI: 10.1002/ejp.1677] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/22/2020] [Accepted: 10/11/2020] [Indexed: 01/26/2023]
Abstract
BACKGROUND AND OBJECTIVE Metabolomics deals with the identification and quantification of small molecules (metabolites) in biological samples. As metabolite levels can reflect normal or altered metabolic pathways, their measurement provides information to improve the understanding, diagnosis and management of diseases. Despite its immense potential, metabolomics applications to pain research have been sparse. This paper describes current metabolomics techniques, reviews published human metabolomics pain research and compares successful metabolomics research in other areas of medicine with the goal of highlighting opportunities offered by metabolomics to advance pain medicine. DATABASES AND DATA TREATMENT Non-systematic review. RESULTS Our search identified 19 studies that adopted a metabolomics approach in: fibromyalgia (7), chronic widespread pain (4), other musculoskeletal pain conditions (5), neuropathic pain (1), complex regional pain syndrome (1) and pelvic pain (1). The studies used either mass spectrometry or nuclear magnetic resonance. Most are characterized by small sample sizes. Some consistency has been found for alterations in glutamate and testosterone metabolism, and metabolic imbalances caused by the gut microbiome. CONCLUSIONS Metabolomics research in chronic pain is in its infancy. Most studies are at the pilot stage. Metabolomics research has been successful in other areas of medicine. These achievements should motivate investigators to expand metabolomics research to improve the understanding of the basic mechanisms of human pain, as well as provide tools to diagnose, predict and monitor chronic pain conditions. Metabolomics research can lead to the identification of biomarkers to support the development and testing of treatments, thereby facilitating personalized pain medicine.
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Affiliation(s)
- Shweta Teckchandani
- Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA, USA
| | - G A Nagana Gowda
- Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA, USA.,Northwest Metabolomics Research Center, Mitochondria and Metabolism Center, University of Washington, Seattle, WA, USA
| | - Daniel Raftery
- Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA, USA.,Northwest Metabolomics Research Center, Mitochondria and Metabolism Center, University of Washington, Seattle, WA, USA
| | - Michele Curatolo
- Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA, USA.,Harborview Injury Prevention and Research Center, University of Washington, Seattle, WA, USA.,CLEAR Research Center for Musculoskeletal Disorders, University of Washington, Seattle, WA, USA
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Abstract
In the peripheral nervous system, the vast majority of axons are accommodated within the fibre bundles that constitute the peripheral nerves. Axons within the nerves are in close contact with myelinating glia, the Schwann cells that are ideally placed to respond to, and possibly shape, axonal activity. The mechanisms of intercellular communication in the peripheral nerves may involve direct contact between the cells, as well as signalling via diffusible substances. Neurotransmitter glutamate has been proposed as a candidate extracellular molecule mediating the cross-talk between cells in the peripheral nerves. Two types of experimental findings support this idea: first, glutamate has been detected in the nerves and can be released upon electrical or chemical stimulation of the nerves; second, axons and Schwann cells in the peripheral nerves express glutamate receptors. Yet, the studies providing direct experimental evidence that intercellular glutamatergic signalling takes place in the peripheral nerves during physiological or pathological conditions are largely missing. Remarkably, in the central nervous system, axons and myelinating glia are involved in glutamatergic signalling. This signalling occurs via different mechanisms, the most intriguing of which is fast synaptic communication between axons and oligodendrocyte precursor cells. Glutamate receptors and/or synaptic axon-glia signalling are involved in regulation of proliferation, migration, and differentiation of oligodendrocyte precursor cells, survival of oligodendrocytes, and re-myelination of axons after damage. Does synaptic signalling exist between axons and Schwann cells in the peripheral nerves? What is the functional role of glutamate receptors in the peripheral nerves? Is activation of glutamate receptors in the nerves beneficial or harmful during diseases? In this review, we summarise the limited information regarding glutamate release and glutamate receptors in the peripheral nerves and speculate about possible mechanisms of glutamatergic signalling in the nerves. We highlight the necessity of further research on this topic because it should help to understand the mechanisms of peripheral nervous system development and nerve regeneration during diseases.
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Affiliation(s)
- Ting-Jiun Chen
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Centre, Washington, DC, USA
| | - Maria Kukley
- Group of Neuron Glia Interaction, University of Tübingen; Research Institute of Ophthalmology, Tübingen University Hospital, Tübingen, Germany
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9
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Okutani H, Yamanaka H, Kobayashi K, Okubo M, Noguchi K. Recombinant interleukin-4 alleviates mechanical allodynia via injury-induced interleukin-4 receptor alpha in spinal microglia in a rat model of neuropathic pain. Glia 2018; 66:1775-1787. [DOI: 10.1002/glia.23340] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 03/26/2018] [Accepted: 03/26/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Hiroai Okutani
- Department of Anatomy and Neuroscience; Hyogo College of Medicine, 1-1 Mukogawa-cho; Nishinomiya Hyogo 663-8501 Japan
| | - Hiroki Yamanaka
- Department of Anatomy and Neuroscience; Hyogo College of Medicine, 1-1 Mukogawa-cho; Nishinomiya Hyogo 663-8501 Japan
| | - Kimiko Kobayashi
- Department of Anatomy and Neuroscience; Hyogo College of Medicine, 1-1 Mukogawa-cho; Nishinomiya Hyogo 663-8501 Japan
| | - Masamichi Okubo
- Department of Anatomy and Neuroscience; Hyogo College of Medicine, 1-1 Mukogawa-cho; Nishinomiya Hyogo 663-8501 Japan
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience; Hyogo College of Medicine, 1-1 Mukogawa-cho; Nishinomiya Hyogo 663-8501 Japan
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10
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Bai W, Zhou YG. Homeostasis of the Intraparenchymal-Blood Glutamate Concentration Gradient: Maintenance, Imbalance, and Regulation. Front Mol Neurosci 2017; 10:400. [PMID: 29259540 PMCID: PMC5723322 DOI: 10.3389/fnmol.2017.00400] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/20/2017] [Indexed: 12/25/2022] Open
Abstract
It is widely accepted that glutamate is the most important excitatory neurotransmitter in the central nervous system (CNS). However, there is also a large amount of glutamate in the blood. Generally, the concentration gradient of glutamate between intraparenchymal and blood environments is stable. However, this gradient is dramatically disrupted under a variety of pathological conditions, resulting in an amplifying cascade that causes a series of pathological reactions in the CNS and peripheral organs. This eventually seriously worsens a patient’s prognosis. These two “isolated” systems are rarely considered as a whole even though they mutually influence each other. In this review, we summarize what is currently known regarding the maintenance, imbalance and regulatory mechanisms that control the intraparenchymal-blood glutamate concentration gradient, discuss the interrelationships between these systems and further explore their significance in clinical practice.
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Affiliation(s)
- Wei Bai
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, China
| | - Yuan-Guo Zhou
- Molecular Biology Center, State Key Laboratory of Trauma, Burn, and Combined Injury, Research Institute of Surgery and Daping Hospital, Third Military Medical University, Chongqing, China
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11
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Lian YN, Lu Q, Chang JL, Zhang Y. The role of glutamate and its receptors in central nervous system in stress-induced hyperalgesia. Int J Neurosci 2017; 128:283-290. [DOI: 10.1080/00207454.2017.1387112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Yan-Na Lian
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Qi Lu
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Jin-Long Chang
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
| | - Ying Zhang
- Department of Physiology, Harbin Medical University, Harbin, P. R. China
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12
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Weaver JL, Arandjelovic S, Brown G, K Mendu S, S Schappe M, Buckley MW, Chiu YH, Shu S, Kim JK, Chung J, Krupa J, Jevtovic-Todorovic V, Desai BN, Ravichandran KS, Bayliss DA. Hematopoietic pannexin 1 function is critical for neuropathic pain. Sci Rep 2017; 7:42550. [PMID: 28195232 PMCID: PMC5307344 DOI: 10.1038/srep42550] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 01/12/2017] [Indexed: 12/13/2022] Open
Abstract
Neuropathic pain symptoms respond poorly to available therapeutics, with most treated patients reporting unrelieved pain and significant impairment in daily life. Here, we show that Pannexin 1 (Panx1) in hematopoietic cells is required for pain-like responses following nerve injury in mice, and a potential therapeutic target. Panx1 knockout mice (Panx1-/-) were protected from hypersensitivity in two sciatic nerve injury models. Bone marrow transplantation studies show that expression of functional Panx1 in hematopoietic cells is necessary for mechanical hypersensitivity following nerve injury. Reconstitution of irradiated Panx1 knockout mice with hematopoietic Panx1-/- cells engineered to re-express Panx1 was sufficient to recover hypersensitivity after nerve injury; this rescue required expression of a Panx1 variant that can be activated by G protein-coupled receptors (GPCRs). Finally, chemically distinct Panx1 inhibitors blocked development of nerve injury-induced hypersensitivity and partially relieved this hypersensitivity after it was established. These studies indicate that Panx1 expressed in immune cells is critical for pain-like effects following nerve injury in mice, perhaps via a GPCR-mediated activation mechanism, and suggest that inhibition of Panx1 may be useful in treating neuropathic pain.
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Affiliation(s)
- Janelle L Weaver
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Sanja Arandjelovic
- Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA.,Carter Immunology Center, University of Virginia, Charlottesville, Virginia 22908, USA.,Center for Cell Clearance, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Gregory Brown
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Suresh K Mendu
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Michael S Schappe
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Monica W Buckley
- Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA.,Carter Immunology Center, University of Virginia, Charlottesville, Virginia 22908, USA.,Center for Cell Clearance, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Yu-Hsin Chiu
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Shaofang Shu
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jin K Kim
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Joyce Chung
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Julia Krupa
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | | | - Bimal N Desai
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Kodi S Ravichandran
- Department of Microbiology, Immunology, Cancer Biology, University of Virginia, Charlottesville, Virginia 22908, USA.,Carter Immunology Center, University of Virginia, Charlottesville, Virginia 22908, USA.,Center for Cell Clearance, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908, USA
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13
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Tabakoff B, Ren W, Vanderlinden L, Snell LD, Matheson CJ, Wang ZJ, Levinson R, Smothers CT, Woodward JJ, Honse Y, Lovinger D, Rush AM, Sather WA, Gustafson DL, Hoffman PL. A novel substituted aminoquinoline selectively targets voltage-sensitive sodium channel isoforms and NMDA receptor subtypes and alleviates chronic inflammatory and neuropathic pain. Eur J Pharmacol 2016; 784:1-14. [PMID: 27158117 DOI: 10.1016/j.ejphar.2016.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 12/19/2022]
Abstract
Recent understanding of the systems that mediate complex disease states, has generated a search for molecules that simultaneously modulate more than one component of a pathologic pathway. Chronic pain syndromes are etiologically connected to functional changes (sensitization) in both peripheral sensory neurons and in the central nervous system (CNS). These functional changes involve modifications of a significant number of components of signal generating, signal transducing and signal propagating pathways. Our analysis of disease-related changes which take place in sensory neurons during sensitization led to the design of a molecule that would simultaneously inhibit peripheral NMDA receptors and voltage sensitive sodium channels. In the current report, we detail the selectivity of N,N-(diphenyl)-4-ureido-5,7-dichloro-2-carboxy-quinoline (DCUKA) for action at NMDA receptors composed of different subunit combinations and voltage sensitive sodium channels having different α subunits. We show that DCUKA is restricted to the periphery after oral administration, and that circulating blood levels are compatible with its necessary concentrations for effects at the peripheral cognate receptors/channels that were assayed in vitro. Our results demonstrate that DCUKA, at concentrations circulating in the blood after oral administration, can modulate systems which are upregulated during peripheral sensitization, and are important for generating and conducting pain information to the CNS. Furthermore, we demonstrate that DCUKA ameliorates the hyperalgesia of chronic pain without affecting normal pain responses in neuropathic and inflammation-induced chronic pain models.
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Affiliation(s)
- Boris Tabakoff
- Lohocla Research Corporation, Colorado Bioscience Building, 12635 East Montview Blvd., Suite 128, Aurora, CO 80045, USA; Department of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Campus Box: C238 12850, E. Montview Blvd., Aurora, CO 80045, USA.
| | - Wenhua Ren
- Lohocla Research Corporation, Colorado Bioscience Building, 12635 East Montview Blvd., Suite 128, Aurora, CO 80045, USA.
| | - Lauren Vanderlinden
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Campus Box: C238 12850, E. Montview Blvd., Aurora, CO 80045, USA.
| | - Lawrence D Snell
- Lohocla Research Corporation, Colorado Bioscience Building, 12635 East Montview Blvd., Suite 128, Aurora, CO 80045, USA.
| | - Christopher J Matheson
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Campus Box: C238 12850, E. Montview Blvd., Aurora, CO 80045, USA.
| | - Ze-Jun Wang
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, 12800 E. 19 Ave., Aurora, CO 80045 USA.
| | - Rock Levinson
- Department of Physiology & Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, USA.
| | - C Thetford Smothers
- Department of Neurosciences and Department of Psychiatry, Medical University of South Carolina, 171 Ashley Ave., Charleston, SC 29425, USA.
| | - John J Woodward
- Department of Neurosciences and Department of Psychiatry, Medical University of South Carolina, 171 Ashley Ave., Charleston, SC 29425, USA.
| | - Yumiko Honse
- Clinical and Biological Research Unit, NIAAA, 12420 Parklawn Dr., MSC 8115, Bethesda, MD 20892-8115, USA.
| | - David Lovinger
- Clinical and Biological Research Unit, NIAAA, 12420 Parklawn Dr., MSC 8115, Bethesda, MD 20892-8115, USA.
| | | | - William A Sather
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, 12800 E. 19 Ave., Aurora, CO 80045 USA.
| | - Daniel L Gustafson
- UCCC Pharmacology Shared Resource, Colorado State University, Veterinary Teaching Hospital, A CC246, 300 West Drake Road, Fort Collins, CO 80023, USA.
| | - Paula L Hoffman
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, 12800 E. 19 Ave., Aurora, CO 80045 USA.
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Differential Efficacy of Ketamine in the Acute versus Chronic Stages of Complex Regional Pain Syndrome in Mice. Anesthesiology 2016; 123:1435-47. [PMID: 26492479 DOI: 10.1097/aln.0000000000000889] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Complex regional pain syndrome (CRPS) is a painful, disabling, and often chronic condition, where many patients transition from an acute phase with prominent peripheral neurogenic inflammation to a chronic phase with evident central nervous system changes. Ketamine is a centrally acting agent believed to work through blockade of N-methyl-D- aspartate receptors and is being increasingly used for the treatment of refractory CRPS, although the basis for the drug's effects and efficacy at different stages of the syndrome remains unclear. METHODS The authors used a mouse model of CRPS (n = 8 to 12/group) involving tibia fracture/cast immobilization to test the efficacy of ketamine (2 mg kg day; 7 days) or vehicle infusion during acute (3 weeks after fracture) and chronic (7 weeks after fracture) stages. RESULTS Acute-phase fracture mice displayed increased limb temperature, edema, and nociceptive sensitization that were not reduced by ketamine. Fracture mice treated with ketamine during the chronic phase showed reduced nociceptive sensitization that persisted beyond completion of the infusion. During this chronic phase, ketamine also reduced latent nociceptive sensitization and improved motor function at 18 weeks after fracture. No side effects of the infusions were identified. These behavioral changes were associated with altered spinal astrocyte activation and expression of pain-related proteins including N-methyl-D-aspartate receptor 2b, Ca/calmodulin-dependent protein kinase II, and brain-derived neurotrophic factor. CONCLUSIONS Collectively, these results demonstrate that ketamine is efficacious in the chronic, but not acute, stage of CRPS, suggesting that the centrally acting drug is relatively ineffective in early CRPS when peripheral mechanisms are more critical for supporting nociceptive sensitization.
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Ke T, Li R, Chen W. Inhibition of the NMDA receptor protects the rat sciatic nerve against ischemia/reperfusion injury. Exp Ther Med 2016; 11:1563-1572. [PMID: 27168774 PMCID: PMC4840580 DOI: 10.3892/etm.2016.3148] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 11/25/2015] [Indexed: 12/23/2022] Open
Abstract
Inhibition of the N-methyl-D-aspartate (NMDA) receptor by MK-801 reduces ischemia/reperfusion (I/R) injury in the central nervous system. However, few previous studies have evaluated the neuroprotective effects of MK-801 against peripheral I/R injury. The present study aimed to investigate the protective effects of MK-801 pretreatment against I/R injury in the rat sciatic nerve (SN). Sprague-Dawley rats were subjected to a sham surgery (n=8) or to a 5-h ischemic insult by femoral artery clamping (I/R and I/R+MK-801 groups; n=48 per group). I/R+MK-801 rats were intraperitoneally injected with MK-801 (0.5 ml or 1 mg/kg) at 15 min prior to reperfusion. The rats were sacrificed at 0, 6, 12, 24, 72 h, or 7 days following reperfusion. Plasma malondialdehyde (MDA) and nitric oxide (NO) concentrations, and SN inducible NO synthase (iNOS) protein expression levels, were measured using colorimetry. In addition, the protein expression levels of tumor necrosis factor-α (TNF-α) were measured using immunohistochemistry, and histological analyses of the rat SN were conducted using light and electron microscopy. Alterations in the mRNA expression levels of TNF-α and TNF-α converting enzyme (TACE) in the rat SN were detected using reverse transcription-quantitative polymerase chain reaction. In the I/R group, plasma concentrations of NO (175.3±4.2 µmol/l) and MDA (16.2±1.9 mmol/l), and the levels of iNOS (2.5±0.3) in the SN, peaked at 24 h post-reperfusion. At 24 h, pretreatment with MK-801 significantly reduced plasma NO (107.3±3.6 µmol/l) and MDA (11.8±1.6 mmol/l), and SN iNOS (1.65±0.2) levels (all P<0.01). The mRNA expression levels of TNF-α and TACE in the SN were significantly reduced in the I/R+MK-801 group, as compared with the I/R group (P<0.05). Furthermore, MK-801 pretreatment was shown to have alleviated histological signs of I/R injury, including immune cell infiltration and axon demyelination. The results of the present study suggested that pretreatment with MK-801 may alleviate I/R injury of the SN by inhibiting the activation of TNF-α and reducing the levels of iNOS in the SN.
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Affiliation(s)
- Tie Ke
- Department of Emergency Surgery, Fujian Provincial Hospital, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China; Emergency Center of Fujian Province, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China; Provincial Clinical Medical College, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
| | - Renbin Li
- Department of Orthopedics, The Affiliated Fuzhou Second Hospital, Xiamen University, Fuzhou, Fujian 350007, P.R. China
| | - Wenchang Chen
- Department of Emergency Surgery, Fujian Provincial Hospital, Fujian Medical University, Fuzhou, Fujian 350001, P.R. China
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16
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Kwon SG, Yoon SY, Roh DH, Choi SR, Choi HS, Moon JY, Kang SY, Beitz AJ, Lee JH. Peripheral neurosteroids enhance P2X receptor-induced mechanical allodynia via a sigma-1 receptor-mediated mechanism. Brain Res Bull 2016; 121:227-32. [PMID: 26876754 DOI: 10.1016/j.brainresbull.2016.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/09/2016] [Accepted: 02/10/2016] [Indexed: 10/22/2022]
Abstract
The role of peripheral neurosteroids and their related mechanisms on nociception have not been thoroughly investigated. Based on emerging evidence in the literature indicating that neurosteroids and their main target receptors, i.e., sigma-1, GABAA and NMDA, affect P2X-induced changes in neuronal activity, this study was designed to investigate the effect of peripherally injected dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulfate (PREGS) on P2X receptor-mediated mechanical allodynia in rats. Intraplantar injection of either neurosteroids alone did not produced any detectable changes in paw withdrawal frequency to the innocuous mechanical stimulation in naïve rats. However, When DHEAS or PREGS were co-injected with a sub-effective dose of αβmeATP, mechanical allodynia was developed and this was dose dependently blocked by pre-injection of the P2X antagonist, TNP-ATP. These results demonstrates that DHEAS and PREGS potentiate the activity of P2X receptors which results in the enhancement of αβmeATP-induced mechanical allodynia. In order to investigate the potential role of peripheral sigma-1, GABAA and NMDA receptors in this facilitatory action, we pretreated animals with BD-1047 (a sigma-1 antagonist), muscimol (a GABAA agonist) or MK-801 (a NMDA antagonist) prior to DHEAS or PREGS+αβmeATP injection. Only BD-1047 effectively prevented the facilitatory effects induced by neurosteroids on αβmeATP-induced mechanical allodynia. Collectively, we have shown that peripheral neurosteroids potentiate P2X-induced mechanical allodynia and that this action is mediated by sigma-1, but not by GABAA nor NMDA, receptors.
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Affiliation(s)
- Soon-Gu Kwon
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Seo-Yeon Yoon
- Pain Cognitive Function Research Center, Department of Brain and Cognitive Sciences College of Natural Sciences, Seoul National University, Seoul, Republic of Korea; Department of Neurobiology and Physiology, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Dae-Hyun Roh
- Department of Maxillofacial Tissue Regeneration, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea
| | - Sheu-Ran Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Hoon-Seong Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Ji-Young Moon
- KM Fundamental Research Division, Korea Institute of Oriental Medicine, Daejeon 305-811, Republic of Korea
| | - Suk-Yun Kang
- KM Fundamental Research Division, Korea Institute of Oriental Medicine, Daejeon 305-811, Republic of Korea
| | - Alvin J Beitz
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA
| | - Jang-Hern Lee
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.
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17
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Moon YE, Choi JH, Park HJ, Park JH, Kim JH. Ultrasound-Guided Nerve Block with Botulinum Toxin Type A for Intractable Neuropathic Pain. Toxins (Basel) 2016; 8:toxins8010018. [PMID: 26761032 PMCID: PMC4728540 DOI: 10.3390/toxins8010018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/02/2016] [Accepted: 01/05/2016] [Indexed: 11/30/2022] Open
Abstract
Neuropathic pain includes postherpetic neuralgia (PHN), painful diabetic neuropathy (PDN), and trigeminal neuralgia, and so on. Although various drugs have been tried to treat neuropathic pain, the effectiveness of the drugs sometimes may be limited for chronic intractable neuropathic pain, especially when they cannot be used at an adequate dose, due to undesirable severe side effects and the underlying disease itself. Botulinum toxin type A (BoNT-A) has been known for its analgesic effect in various pain conditions. Nevertheless, there are no data of nerve block in PHN and PDN. Here, we report two patients successfully treated with ultrasound-guided peripheral nerve block using BoNT-A for intractable PHN and PDN. One patient had PHN on the left upper extremity and the other patient had PDN on a lower extremity. Due to side effects of drugs, escalation of the drug dose could not be made. We injected 50 Botox units (BOTOX®, Allergan Inc., Irvine, CA, USA) into brachial plexus and lumbar plexus, respectively, under ultrasound. Their pain was significantly decreased for about 4–5 months. Ultrasound-guided nerve block with BoNT-A may be an effective analgesic modality in a chronic intractable neuropathic pain especially when conventional treatment failed to achieve adequate pain relief.
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Affiliation(s)
- Young Eun Moon
- Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 222 Banpo-Daero, Seoul 137-701, Korea.
| | - Jung Hyun Choi
- Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 222 Banpo-Daero, Seoul 137-701, Korea.
| | - Hue Jung Park
- Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 222 Banpo-Daero, Seoul 137-701, Korea.
| | - Ji Hye Park
- Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 222 Banpo-Daero, Seoul 137-701, Korea.
| | - Ji Hyun Kim
- Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 222 Banpo-Daero, Seoul 137-701, Korea.
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18
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Peripheral NMDA Receptors Mediate Antidromic Nerve Stimulation-Induced Tactile Hypersensitivity in the Rat. Mediators Inflamm 2015; 2015:793624. [PMID: 26770021 PMCID: PMC4681795 DOI: 10.1155/2015/793624] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/19/2015] [Indexed: 12/16/2022] Open
Abstract
We investigated the role of peripheral NMDA receptors (NMDARs) in antidromic nerve stimulation-induced tactile hypersensitivity outside the skin area innervated by stimulated nerve. Tetanic electrical stimulation (ES) of the decentralized L5 spinal nerve, which induced enlargement of plasma extravasation, resulted in tactile hypersensitivity in the L4 plantar dermatome of the hind-paw. When intraplantar (i.pl.) injection was administered into the L4 dermatome before ES, NMDAR and group-I metabotropic Glu receptor (mGluR) antagonists and group-II mGluR agonist but not AMPA/kainate receptor antagonist prevented ES-induced hypersensitivity. I.pl. injection of PKA or PKC inhibitors also prevented ES-induced hypersensitivity. When the same injections were administered after establishment of ES-induced hypersensitivity, hypersensitivity was partially reduced by NMDAR antagonist only. In naïve animals, i.pl. Glu injection into the L4 dermatome induced tactile hypersensitivity, which was blocked by NMDAR antagonist and PKA and PKC inhibitors. These results suggest that the peripheral release of Glu, induced by antidromic nerve stimulation, leads to the expansion of tactile hypersensitive skin probably via nociceptor sensitization spread due to the diffusion of Glu into the skin near the release site. In addition, intracellular PKA- and PKC-dependent mechanisms mediated mainly by NMDAR activation are involved in Glu-induced nociceptor sensitization and subsequent hypersensitivity.
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19
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Miladinovic T, Nashed MG, Singh G. Overview of Glutamatergic Dysregulation in Central Pathologies. Biomolecules 2015; 5:3112-41. [PMID: 26569330 PMCID: PMC4693272 DOI: 10.3390/biom5043112] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 12/27/2022] Open
Abstract
As the major excitatory neurotransmitter in the mammalian central nervous system, glutamate plays a key role in many central pathologies, including gliomas, psychiatric, neurodevelopmental, and neurodegenerative disorders. Post-mortem and serological studies have implicated glutamatergic dysregulation in these pathologies, and pharmacological modulation of glutamate receptors and transporters has provided further validation for the involvement of glutamate. Furthermore, efforts from genetic, in vitro, and animal studies are actively elucidating the specific glutamatergic mechanisms that contribute to the aetiology of central pathologies. However, details regarding specific mechanisms remain sparse and progress in effectively modulating glutamate to alleviate symptoms or inhibit disease states has been relatively slow. In this report, we review what is currently known about glutamate signalling in central pathologies. We also discuss glutamate's mediating role in comorbidities, specifically cancer-induced bone pain and depression.
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Affiliation(s)
- Tanya Miladinovic
- Department of Pathology and Molecular Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada.
| | - Mina G Nashed
- Department of Pathology and Molecular Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada.
| | - Gurmit Singh
- Department of Pathology and Molecular Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada.
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20
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Nerve demyelination increases metabotropic glutamate receptor subtype 5 expression in peripheral painful mononeuropathy. Int J Mol Sci 2015; 16:4642-65. [PMID: 25739080 PMCID: PMC4394440 DOI: 10.3390/ijms16034642] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 02/12/2015] [Accepted: 02/13/2015] [Indexed: 01/24/2023] Open
Abstract
Wallerian degeneration or nerve demyelination, arising from spinal nerve compression, is thought to bring on chronic neuropathic pain. The widely distributed metabotropic glutamate receptor subtype 5 (mGluR5) is involved in modulating nociceptive transmission. The purpose of this study was to investigate the potential effects of mGluR5 on peripheral hypersensitivities after chronic constriction injury (CCI). Sprague-Dawley rats were operated on with four loose ligatures around the sciatic nerve to induce thermal hyperalgesia and mechanical allodynia. Primary afferents in dermis after CCI exhibited progressive decreases, defined as partial cutaneous denervation; importantly, mGluR5 expressions in primary afferents were statistically increased. CCI-induced neuropathic pain behaviors through the intraplantar injections of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective mGluR5 antagonist, were dose-dependently attenuated. Furthermore, the most increased mGluR5 expressions in primary afferents surrounded by reactive Schwann cells were observed at the distal CCI stumps of sciatic nerves. In conclusion, these results suggest that nerve demyelination results in the increases of mGluR5 expression in injured primary afferents after CCI; and further suggest that mGluR5 represents a main therapeutic target in developing pharmacological strategies to prevent peripheral hypersensitivities.
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21
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Rogoz K, Stjärne L, Kullander K, Lagerström MC. VGLUT2 controls heat and punctuate hyperalgesia associated with nerve injury via TRPV1-Cre primary afferents. PLoS One 2015; 10:e0116568. [PMID: 25615623 PMCID: PMC4304805 DOI: 10.1371/journal.pone.0116568] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 12/11/2014] [Indexed: 12/04/2022] Open
Abstract
Nerve injury induces a state of prolonged thermal and mechanical hypersensitivity in the innervated area, causing distress in affected individuals. Nerve injury-induced hypersensitivity is partially due to increased activity and thereby sustained release of neurotransmitters from the injured fibers. Glutamate, a prominent neurotransmitter in primary afferents, plays a major role in development of hypersensitivity. Glutamate is packed in vesicles by vesicular glutamate transporters (VGLUTs) to enable controlled release upon depolarization. While a role for peripheral VGLUTs in nerve injury-induced pain is established, their contribution in specific peripheral neuronal populations is unresolved. We investigated the role of VGLUT2, expressed by transient receptor potential vanilloid (TRPV1) fibers, in nerve injury-induced hypersensitivity. Our data shows that removal of Vglut2 from Trpv1-Cre neurons using transgenic mice abolished both heat and punctuate hyperalgesia associated with nerve injury. In contrast, the development of cold hypersensitivity after nerve injury was unaltered. Here, we show that, VGLUT2-mediated glutamatergic transmission from Trpv1-Cre neurons selectively mediates heat and mechanical hypersensitivity associated with nerve injury. Our data clarifies the role of the Trpv1-Cre population and the dependence of VGLUT2-mediated glutamatergic transmission in nerve injury-induced hyperalgesia.
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Affiliation(s)
- Katarzyna Rogoz
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Ludvig Stjärne
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Klas Kullander
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
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22
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Nilsson M, Lassen D, Andresen T, Nielsen AK, Arendt-Nielsen L, Drewes AM. Intradermal glutamate and capsaicin injections: intra- and interindividual variability of provoked hyperalgesia and allodynia. Clin Exp Pharmacol Physiol 2015; 41:423-9. [PMID: 24684312 DOI: 10.1111/1440-1681.12229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/20/2014] [Accepted: 03/22/2014] [Indexed: 11/30/2022]
Abstract
Intradermal injections of glutamate and capsaicin are attractive to use in human experimental pain models because hyperalgesia and allodynia mimic isolated aspects of clinical pain disorders. The aim of the present study was to investigate the reproducibility of these models. Twenty healthy male volunteers (mean age 24 years; range 18-38 years) received intradermal injections of glutamate and capsaicin in the volar forearm. Magnitudes of secondary pinprick hyperalgesia and brush-evoked allodynia were investigated using von Frey filaments (gauges 10, 15, 60 and 100 g) and brush strokes. Areas of secondary hyperalgesia and allodynia were quantified immediately after injection and after 15, 30 and 60 min. Two identical experiments separated by at least 7 days were performed. Reproducibility across and within volunteers (inter- and intra-individual variation, respectively) was assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CV). Secondary pinprick hyperalgesia was observed as a marked increase in the visual analogue scale (VAS) response to von Frey gauges 60 and 100 g (P < 0.001) after glutamate injection. For capsaicin, secondary pinprick hyperalgesia was detected with all von Frey gauges (P < 0.001). Glutamate evoked reproducible VAS response to all von Frey gauges (ICC > 0.60) and brush strokes (ICC > 0.83). Capsaicin injection was reproducible for secondary hyperalgesia (ICC > 0.70) and allodynia (ICC > 0.71). Intra-individual variability was generally lower for the VAS response to von Frey and brush compared with areas of secondary hyperalgesia and allodynia. In conclusion, glutamate and capsaicin yield reproducible hyperalgesic and allodynic responses, and the present model is well suited for basic research, as well as for assessing the modulation of central phenomena.
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Affiliation(s)
- Matias Nilsson
- Mech-Sense, Department of Gastroenterology & Hepatology, Aalborg University Hospital, Aalborg University, Aalborg, Denmark
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23
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Palazzo E, Marabese I, de Novellis V, Rossi F, Maione S. Supraspinal metabotropic glutamate receptors: a target for pain relief and beyond. Eur J Neurosci 2014; 39:444-54. [PMID: 24494684 DOI: 10.1111/ejn.12398] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/20/2013] [Accepted: 09/23/2013] [Indexed: 01/09/2023]
Abstract
Glutamate is the main excitatory neurotransmitter in the central nervous system, controlling the majority of synapses. Apart from neurodegenerative diseases, growing evidence suggests that glutamate is involved in psychiatric and neurological disorders, including pain. Glutamate signaling is mediated via ionotropic glutamate receptors (iGluRs) and metabotropic glutamate receptors (mGluRs). So far, drugs acting via modulation of glutamatergic system are few in number, and all are associated with iGluRs and important side effects. The glutamatergic system may be finely modulated by mGluRs. Signaling via these receptors is slower and longer-lasting, and permits fine-tuning of glutamate transmission. There have been eight mGluRs cloned to date (mGluR1-mGluR8), and these are further divided into three groups on the basis of sequence homology, pharmacological profile, and second messenger signaling. The pattern of expression of mGluRs along the pain neuraxis makes them suitable substrates for the design of novel analgesics. This review will focus on the supraspinal mGluRs, whose pharmacological manipulation generates a variety of effects, which depend on the synaptic location, the cell type on which they are located, and the expression in particular pain modulation areas, such as the periaqueductal gray, which plays a major role in the descending modulation of pain, and the central nucleus of the amygdala, which is an important center for the processing of emotional information associated with pain. A particular emphasis will also be given to the novel selective mGluR subtype ligands, as well as positive and negative allosteric modulators, which have permitted discrimination of the individual roles of the different mGluR subtypes, and subtle modulation of central nervous system functioning and related disorders.
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Affiliation(s)
- Enza Palazzo
- Department of Anaesthesiology, Surgery and Emergency, The Second University of Naples, Piazza Luigi Miraglia 2, 80138, Naples, Italy
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Increased response to glutamate in small diameter dorsal root ganglion neurons after sciatic nerve injury. PLoS One 2014; 9:e95491. [PMID: 24748330 PMCID: PMC3991716 DOI: 10.1371/journal.pone.0095491] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/26/2014] [Indexed: 12/24/2022] Open
Abstract
Glutamate in the peripheral nervous system is involved in neuropathic pain, yet we know little how nerve injury alters responses to this neurotransmitter in primary sensory neurons. We recorded neuronal responses from the ex-vivo preparations of the dorsal root ganglia (DRG) one week following a chronic constriction injury (CCI) of the sciatic nerve in adult rats. We found that small diameter DRG neurons (<30 µm) exhibited increased excitability that was associated with decreased membrane threshold and rheobase, whereas responses in large diameter neurons (>30 µm) were unaffected. Puff application of either glutamate, or the selective ionotropic glutamate receptor agonists alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainic acid (KA), or the group I metabotropic receptor (mGluR) agonist (S)-3,5-dihydroxyphenylglycine (DHPG), induced larger inward currents in CCI DRGs compared to those from uninjured rats. N-methyl-D-aspartate (NMDA)-induced currents were unchanged. In addition to larger inward currents following CCI, a greater number of neurons responded to glutamate, AMPA, NMDA, and DHPG, but not to KA. Western blot analysis of the DRGs revealed that CCI resulted in a 35% increase in GluA1 and a 60% decrease in GluA2, the AMPA receptor subunits, compared to uninjured controls. mGluR1 receptor expression increased by 60% in the membrane fraction, whereas mGluR5 receptor subunit expression remained unchanged after CCI. These results show that following nerve injury, small diameter DRG neurons, many of which are nociceptive, have increased excitability and an increased response to glutamate that is associated with changes in receptor expression at the neuronal membrane. Our findings provide further evidence that glutamatergic transmission in the periphery plays a role in nociception.
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Plasma amino acids changes in complex regional pain syndrome. PAIN RESEARCH AND TREATMENT 2013; 2013:742407. [PMID: 24303215 PMCID: PMC3835366 DOI: 10.1155/2013/742407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 09/18/2013] [Accepted: 09/22/2013] [Indexed: 11/18/2022]
Abstract
Complex regional pain syndrome (CRPS) is a severe chronic pain condition that most often develops following trauma. Blood samples were collected from 220 individuals, 160 CRPS subjects, and 60 healthy pain-free controls. Plasma amino acid levels were compared and contrasted between groups. L-Aspartate, L-glutamate, and L-ornithine were significantly increased, whereas L-tryptophan and L-arginine were significantly decreased in CRPS subjects as compared to controls. In addition, the L-kynurenine to L-tryptophan ratio demonstrated a significant increase, whereas the global arginine bioavailability ratio (GABR) was significantly decreased in the CRPS subjects. The CRPS subjects demonstrated a significant correlation between overall pain and the plasma levels of L-glutamate and the L-kynurenine to L-tryptophan ratio. CRPS subjects also showed a correlation between the decrease in plasma L-tryptophan and disease duration. This study shows that CRPS subjects exhibit significant changes in plasma levels of amino acids involved in glutamate receptor activation and in amino acids associated with immune function as compared to healthy pain-free controls. A better understanding of the role plasma amino acids play in the pathophysiology of CRPS may lead to novel treatments for this crippling condition.
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Abstract
Breast cancers are the most common source of metastases to bone, of which cancer-induced bone pain is a frequent pathological feature. Cancer-induced bone pain is a unique pain state with multiple determinants that remains to be well understood and managed. Current standard treatments are limited by dose-dependent side effects that can reduce the quality of life of patients. Glutamate is a neurotransmitter and bone cell-signalling molecule that is released via the system x(c)(-) cystine/glutamate antiporter from cancer cell types that frequently metastasize to bone, including breast cancers. In cancer cells, glutamate release is understood to be a side effect of the cellular response to oxidative stress that upregulates the expression and activity of system x(c)(-) to promote the increased import of cystine. Attenuation of glutamate release from cancer cells has been demonstrated to result in reductions in associated cancer-induced bone pain in animal models. This review examines the clinical implications of attenuating cystine uptake and glutamate release in the treatment of cancer-induced bone pain.
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Affiliation(s)
- Robert G Ungard
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
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Kim HY, Wang J, Gwak YS. Gracile Neurons Contribute to the Maintenance of Neuropathic Pain in Peripheral and Central Neuropathic Models. J Neurotrauma 2012; 29:2587-92. [DOI: 10.1089/neu.2012.2396] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Hee Young Kim
- Department of Physiology, College of Oriental Medicine, Daegu Haany University, Daegu, South Korea
| | - Jigong Wang
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
| | - Young Seob Gwak
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas
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Unezaki S, Sasaki A, Mabuchi T, Matsumura S, Katano T, Nakazawa T, Nishio N, Andoh T, Yamamoto T, Nakatsuka T, Kuraishi Y, Ito S. Involvement of Tyr1472 phosphorylation of NMDA receptor NR2B subunit in postherpetic neuralgia in model mice. Mol Pain 2012; 8:59. [PMID: 22909213 PMCID: PMC3495680 DOI: 10.1186/1744-8069-8-59] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Accepted: 06/13/2012] [Indexed: 11/26/2022] Open
Abstract
Background Postherpetic neuralgia is spontaneous pain and allodynia that persist long after the disappearance of the cutaneous lesions caused by herpes zoster. Inoculation of mice with herpes simplex virus-1 causes herpes zoster-like skin lesions and herpetic and postherpetic pain. Although NMDA receptors have been suggested to be involved in postherpetic pain as in other types of neuropathic pain, the neural mechanism remains unclear. NMDA receptor NR2B subunit is the most tyrosine-phosphorylated protein in the brain, and Tyr1472 is the major phosphorylation site of this subunit. Results To elucidate the role of Tyr1472 phosphorylation of the NR2B subunit in herpetic and postherpetic allodynia, we inoculated herpes simplex virus-1 into the unilateral hind paw of knock-in mice with a mutation of Tyr1472 of the NR2B subunit to Phe (Y1472F-KI). On day 7 post-inoculation, acute herpetic allodynia was observed in more than 80% of the inoculated wild-type and Y1472F-KI mice. Y1472F-KI mice showed significantly reduced intensity and incidence of postherpetic allodynia on days 45–50 post-inoculation as compared with wild-type mice. The innervation in the skin at the postherpetic neuralgia phase was retained to a greater extent in the Y1472F-KI mice. The level of activating transcription factor-3 mRNA, a marker of axonal damage, increased much less in the dorsal root ganglia (DRGs) of Y1472F-KI mice than in those of wild-type mice; and the level of nerve growth factor mRNA significantly increased in wild-type mice, but not at all in Y1472F-KI mice on day 7 post-inoculation. Production of nerve growth factor was at the basal level in the skin of both groups of mice on day 50 post-inoculation. Nerve growth factor and glial cell-derived neurotrophic factor stimulated neurite outgrowth of cultured DRG neurons from Y1472F-KI mice, similarly or less so as they did the outgrowth of those from wild-type mice. Wild-type DRG neurons were more susceptible to glutamate neurotoxicity than Y1472F-KI ones. Conclusions Taken together, the present data suggest that phosphorylation of the NR2B subunit at its Tyr1472 is involved in the development of postherpetic allodynia due to nerve damage and that the nerve damage at the acute herpetic phase is correlated with the incidence of postherpetic pain.
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Affiliation(s)
- Sawako Unezaki
- Department of Medical Chemistry, Kansai Medical University, Moriguchi 570-8506, Japan
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Upregulation of neuronal nitric oxide synthase in the periphery promotes pain hypersensitivity after peripheral nerve injury. Neuroscience 2011; 190:367-78. [DOI: 10.1016/j.neuroscience.2011.05.064] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/09/2011] [Accepted: 05/25/2011] [Indexed: 11/23/2022]
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Jung SS, Sung KW, Lee SE, Shin HK. Capsaicin prevents the hyperalgesia induced by peripheral group I mGluRs activation. Neurosci Lett 2011; 500:197-201. [PMID: 21742015 DOI: 10.1016/j.neulet.2011.06.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/20/2011] [Accepted: 06/21/2011] [Indexed: 11/16/2022]
Abstract
Group 1 metabotropic glutamate receptors (mGluRs) are expressed in peripheral and central neural tissues and involved in peripheral and central sensitization in various pain models. However, there are limited reports that activation of peripheral group I mGluRs could evoke pain. Furthermore, any behavioral evidences could not be found out, showing what kind of afferent fibers are involved in peripheral mGluRs-mediated hyperalgesia. This study was undertaken to clarify whether peripherally injected group I mGluRs agonists could induce pain-related behaviors and capsaicin-sensitive afferent fibers might be involved in the hyperalgesia. To assess pain sensitivity, mechanical threshold for paw withdrawal response (PWT) was measured and number of spontaneous flinching behavior was counted. Intraplantar injection of group I mGluR agonist, (RS)-3,5-dihydroxyphenylglycine (DHPG) and mGluR5 agonist, (RS)-2-chloro-5-hydroxyphenyglycine (CHPG) immediately induced pain-like behaviors, such as decrease of PWT and increased number of flinchings. These agonists-induced pain-like behaviors were blocked by group I mGluRs antagonist, (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA) and mGluR5 antagonist, 2-methyl-6-(phenylethynyl) pyridine hydrochloride (MPEP). Perineural pretreatment of 1% capsaicin solution significantly reduced pain-related behaviors induced by DHPG and CHPG, proposing that capsaicin-sensitive primary afferent fibers could be responsible for the hyperalgesia induced by activation of peripheral group I mGluRs. This study presents the first behavioral evidence that peripheral group I mGluRs activation could induce spontaneous as well as mechanical hyperalgesia and capsaicin-sensitive afferent fiber could be implicated the group I mGluR mediated hyperalgesia.
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Affiliation(s)
- Soo Suk Jung
- Department of Physiology, College of Medicine, Hanyang University, Seoul 133-791, South Korea
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Peripheral administration of NR2 antagonists attenuates orofacial formalin-induced nociceptive behavior in rats. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:982-6. [PMID: 21295101 DOI: 10.1016/j.pnpbp.2011.01.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2010] [Revised: 01/26/2011] [Accepted: 01/26/2011] [Indexed: 11/23/2022]
Abstract
The present study investigated the role of the peripheral NR2 subunits of N-methyl-d-aspartatic acid (NMDA) receptors in inflammatory orofacial pain. Experiments were carried out using adult male Sprague-Dawley rats weighing 220 to 280 g. Formalin (5%, 50 μl) was applied subcutaneously to the vibrissa pad. For each animal, the number of noxious behavioral responses, including rubbing or scratching of the facial region proximal to the injection site, was recorded for 9 sequential 5 min intervals. NR2 subunit antagonists were injected subcutaneously at 20 min prior to formalin injection. The subcutaneous injection of 100 or 200 μg of memantine significantly suppressed the number of scratches in the second phase of the behavioral responses to formalin. The subcutaneous injection of 0.25, 2.5, or 25 μg of 5,7-dichlorokynurenic acid also produced significant antinociceptive effects in the second phase. The subcutaneous injection of AP-5 at high dose produced significant antinociceptive effects in the second phase. The subcutaneous injection of PPPA and Ro 25-6981 both significantly suppressed the number of scratches in the second phase. The antinociceptive doses of memantine (200 μg), 5,7-dichlorokynurenic acid (25 μg), AP-5 (20 μg), PPPA (2.5 μg), or Ro 25-6981 (50 μg) injected into the contralateral hind paw did not affect the number of scratches in both the first and second phases. Moreover, the peripheral administration of NR2 subunit antagonists, including other NMDA receptor blockers, did not produce any motor dysfunction. These results indicate that a targeted blockade of peripheral NR2 receptors is a potentially important new method of treating inflammatory pain in the orofacial area.
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Miller KE, Hoffman EM, Sutharshan M, Schechter R. Glutamate pharmacology and metabolism in peripheral primary afferents: physiological and pathophysiological mechanisms. Pharmacol Ther 2011; 130:283-309. [PMID: 21276816 DOI: 10.1016/j.pharmthera.2011.01.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 01/05/2011] [Indexed: 11/25/2022]
Abstract
In addition to using glutamate as a neurotransmitter at central synapses, many primary sensory neurons release glutamate from peripheral terminals. Primary sensory neurons with cell bodies in dorsal root or trigeminal ganglia produce glutaminase, the synthetic enzyme for glutamate, and transport the enzyme in mitochondria to peripheral terminals. Vesicular glutamate transporters fill neurotransmitter vesicles with glutamate and they are shipped to peripheral terminals. Intense noxious stimuli or tissue damage causes glutamate to be released from peripheral afferent nerve terminals and augmented release occurs during acute and chronic inflammation. The site of action for glutamate can be at the autologous or nearby nerve terminals. Peripheral nerve terminals contain both ionotropic and metabotropic excitatory amino acid receptors (EAARs) and activation of these receptors can lower the activation threshold and increase the excitability of primary afferents. Antagonism of EAARs can reduce excitability of activated afferents and produce antinociception in many animal models of acute and chronic pain. Glutamate injected into human skin and muscle causes acute pain. Trauma in humans, such as arthritis, myalgia, and tendonitis, elevates glutamate levels in affected tissues. There is evidence that EAAR antagonism at peripheral sites can provide relief in some chronic pain sufferers.
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Affiliation(s)
- Kenneth E Miller
- Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, OK 74107, United States.
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Julio-Pieper M, Flor PJ, Dinan TG, Cryan JF. Exciting times beyond the brain: metabotropic glutamate receptors in peripheral and non-neural tissues. Pharmacol Rev 2011; 63:35-58. [PMID: 21228260 DOI: 10.1124/pr.110.004036] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Metabotropic glutamate (mGlu) receptors are G-protein-coupled receptors expressed primarily on neurons and glial cells, where they are located in the proximity of the synaptic cleft. In the central nervous system (CNS), mGlu receptors modulate the effects of l-glutamate neurotransmission in addition to that of a variety of other neurotransmitters. However, mGlu receptors also have a widespread distribution outside the CNS that has been somewhat neglected to date. Based on this expression, diverse roles of mGlu receptors have been suggested in a variety of processes in health and disease including controlling hormone production in the adrenal gland and pancreas, regulating mineralization in the developing cartilage, modulating lymphocyte cytokine production, directing the state of differentiation in embryonic stem cells, and modulating gastrointestinal secretory function. Understanding the role of mGlu receptors in the periphery will also provide a better insight into potential side effects of drugs currently being developed for neurological and psychiatric conditions. This review summarizes the new potential roles of mGlu receptors and raises the possibility of novel pharmacological targets for various disorders.
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Affiliation(s)
- Marcela Julio-Pieper
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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A new metabotropic glutamate receptor agonist with in vivo anti-allodynic activity. Bioorg Med Chem 2010; 18:6089-98. [DOI: 10.1016/j.bmc.2010.06.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/16/2010] [Accepted: 06/17/2010] [Indexed: 11/19/2022]
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35
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Attenuation of neuropathy-induced allodynia following intraplantar injection of pregabalin. Can J Anaesth 2010; 57:664-71. [DOI: 10.1007/s12630-010-9318-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 04/14/2010] [Indexed: 11/30/2022] Open
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Yogeeswari P, Semwal A, Mishra R, Sriram D. Current approaches with the glutamatergic system as targets in the treatment of neuropathic pain. Expert Opin Ther Targets 2010; 13:925-43. [PMID: 19538098 DOI: 10.1517/14728220903029210] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glutamate is the most widely distributed and a major excitatory neurotransmitter in the CNS. It has been found to play a critical role in various physiological functions in which increased glutamate or its subsequent stimulation is thought to have a role in pathophysiological mechanism of various CNS diseases like epilepsy, stroke, depression and pain. Early attempts to develop glutamatergic antagonists failed in clinical studies due to nonselective or competitive antagonism and have a lot of safety issues like loss of cognitive functions, psychomimetic effect and sedation. Neuropathic pain can be described as pain associated with damage or permanent alteration of the peripheral or central nervous system. At present, there are very few effective therapies for neuropathic pain. The current approach includes targeting specific or alternate binding sites of glutamate receptors, resulting in reduced CNS liabilities. Targeting the glutamatergic system shows a better efficacy and fewer side effects, compared with classical drugs for the treatment of neuropathic pain. This review discusses the various targets on glutamatergic system, which includes the receptors, transporters and enzymes, for the treatment of neuropathic pain and their advantages over classical glutamatergic antagonists. The review also highlights the newer drugs in clinical trials for neuropathic pain.
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Affiliation(s)
- Perumal Yogeeswari
- BITS-Pilani, Hyderabad Campus, Pharmacy, Shameerpet mandal, Jawahar Nagar, RR District, 500078, Hyderabad, India.
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Sensitization of rat facial cutaneous mechanoreceptors by activation of peripheral N-methyl-d-aspartate receptors. Brain Res 2010; 1319:70-82. [DOI: 10.1016/j.brainres.2010.01.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 01/07/2010] [Accepted: 01/07/2010] [Indexed: 11/23/2022]
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38
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Zhang M, Ji B, Zou H, Shi J, Zhang Z, Li X, Zhu H, Feng G, Jin M, Yu L, He L, Wan C. Vitamin A depletion alters sensitivity of motor behavior to MK-801 in C57BL/6J mice. Behav Brain Funct 2010; 6:7. [PMID: 20180994 PMCID: PMC2832782 DOI: 10.1186/1744-9081-6-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 01/22/2010] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Vitamin A and its derivatives (retinoids) are crucial for the development, maintenance and morphogenesis of the central nervous system (CNS). Although motor impairment has been reported in postnatal vitamin A depletion rodents, the effect of vitamin A depletion on homeostasis maintaining capability in response to external interference is not clear. METHODS In the current study, we measured the effect of vitamin A depletion on motor ability and pain sensitivity under two different conditions: 1. prior to any injection and 2. after the injection of an N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801). RESULTS Vitamin A depletion mice showed decreased body weight, enhanced locomotor activity, increased rearing and less tail flick latency. Vitamin A depletion also induced hypersensitivity of stereotypy, ataxia, rearing, and tail flick latency to MK-801, but hyposensitivity of locomotion to MK-801. CONCLUSIONS These findings suggest that vitamin A depletion affect broad basal behavior and disrupt homeostasis maintaining capability in response to glutamate perturbation. We provide a useful animal model for assessing the role of vitamin A depletion in regulating animal behavior, and for detecting how neurotransmitter pathways might be involved in vitamin A depletion related behavioral abnormalities.
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Affiliation(s)
- Ming Zhang
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai 200030, PR China
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Jang J, Lee B, Nam T, Kim J, Kim D, Leem J. Peripheral contributions to the mechanical hyperalgesia following a lumbar 5 spinal nerve lesion in rats. Neuroscience 2010; 165:221-32. [DOI: 10.1016/j.neuroscience.2009.09.082] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 09/22/2009] [Accepted: 09/30/2009] [Indexed: 02/04/2023]
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40
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Finch PM, Knudsen L, Drummond PD. Reduction of allodynia in patients with complex regional pain syndrome: A double-blind placebo-controlled trial of topical ketamine. Pain 2009; 146:18-25. [DOI: 10.1016/j.pain.2009.05.017] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 04/22/2009] [Accepted: 05/19/2009] [Indexed: 01/14/2023]
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Carlton SM. Peripheral NMDA receptors revisited - Hope floats. Pain 2009; 146:1-2. [PMID: 19767145 DOI: 10.1016/j.pain.2009.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 08/14/2009] [Indexed: 11/26/2022]
Affiliation(s)
- Susan M Carlton
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1069, USA.
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Chun YH, Frank D, Lee JS, Zhang Y, Auh QS, Ro JY. Peripheral AMPA receptors contribute to muscle nociception and c-fos activation. Neurosci Res 2008; 62:97-104. [PMID: 18655811 DOI: 10.1016/j.neures.2008.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 06/04/2008] [Accepted: 06/16/2008] [Indexed: 10/21/2022]
Abstract
In this study, involvement of peripheral AMPA receptors in mediating craniofacial muscle pain was investigated. AMPA receptor subunits, GluR1 and GluR2, were predominantly expressed in small to medium size neurons but more GluR2 positive labeling were encountered in trigeminal ganglia (TG) of male Sprague Dawley rats. A greater prevalence of GluR2 is reflected by the significantly higher percentage of GluR2 than GluR1 positive masseter afferents. Nocifensive behavior and c-fos immunoreactivity were assessed from the same animals that received intramuscular mustard oil (MO) with or without NBQX, a potent AMPA/KA receptor antagonist. Masseteric MO produced nocifensive hindpaw shaking responses that peaked in the first 30s and gradually diminished over a few minutes. There was a significant difference in both peak and overall MO-induced nocifensive responses between NBQX and vehicle pre-treated rats. Subsequent Fos studies also showed that peripheral NBQX pre-treatment effectively reduced the MO-induced neuronal activation in the subnucleus caudalis of the trigeminal nerve (Vc). These combined results provide compelling evidence that acute muscle nociception is mediated, in part, by peripherally located AMPA/KA receptors, and that blockade of multiple peripheral glutamate receptor subtypes may provide a more effective means of reducing muscular pain and central neuronal activation.
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Affiliation(s)
- Yang-Hyun Chun
- Kyung Hee University, School of Dentistry, Department of Oral Medicine, 1 Hoegi Dong, Dongdaemun Gu, Seoul, Republic of Korea
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Lu Y, Sun YN, Wu X, Sun Q, Liu FY, Xing GG, Wan Y. Role of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit GluR1 in spinal dorsal horn in inflammatory nociception and neuropathic nociception in rat. Brain Res 2008; 1200:19-26. [PMID: 18289517 DOI: 10.1016/j.brainres.2008.01.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 12/05/2007] [Accepted: 01/06/2008] [Indexed: 11/29/2022]
Abstract
The present study aims to investigate changes of spinal cord AMPA receptor GluR1 and its phosphorylation in inflammatory and neuropathic pain. Complete Freund's adjuvant (CFA) injection into the hind paw produced inflammatory thermal hyperalgesia that was assessed by decreased response latency to radiant heat; spinal nerve ligation (SNL) was used to induce mechanical allodynia that was evaluated with von Frey hairs. By method of Western blot, expression of GluR1 (the main subunit of the AMPA receptor) and its phosphorylated forms at serine 845 (pGluR1-Ser845) and at serine 831 (pGluR1-Ser831) in the spinal dorsal horn was observed. It was found that the expression of pGluR1-Ser845 and pGluR1-Ser831 increased significantly at 1 h after CFA injection, reached peak at 4 h and returned to the normal control level at 24 h, while no significant change was detected in GluR1 itself. In contrast, neither GluR1 nor pGluR1 showed any significant change in rats following SNL. These results suggest that phosphorylated GluR1 (pGluR1-Ser845 and pGluR1-Ser831) might play a role in the induction of inflammatory but not neuropathic pain.
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Affiliation(s)
- Yue Lu
- Neuroscience Research Institute, Peking University, 38 Xueyuan Road, Beijing 100083, China
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44
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Liu T, Pang XY, Bai ZT, Chai ZF, Jiang F, Ji YH. Intrathecal injection of glutamate receptor antagonists/agonist selectively attenuated rat pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch. Toxicon 2007; 50:1073-84. [PMID: 17850839 DOI: 10.1016/j.toxicon.2007.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 07/03/2007] [Accepted: 07/24/2007] [Indexed: 10/23/2022]
Abstract
The present study investigated the involvement of spinal glutamate receptors in the induction and maintenance of the pain-related behaviors induced by the venom of scorpion Buthus martensi Karsch (BmK). (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5-10-imine hydrogen maleate (MK-801; 40nmol; a non-competitive NMDA receptor antagonist), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 40nmol; a non-NMDA receptor antagonist), dl-amino-3-phosphonopropionic acid (dl-AP3; 100nmol; a group I metabotropic glutamate receptor antagonist) and 4-aminopyrrolidine-2,4-dicarboxylate (APDC; 100nmol; a group II metabotropic glutamate receptor agonist) were employed. On intrathecal injection of glutamate receptor antagonists/agonist before BmK venom administration by 10min, BmK venom-induced spontaneous nociceptive responses could be suppressed by all tested agents. Primary thermal hyperalgesia could be inhibited by MK-801 and dl-AP3, while bilateral mechanical hyperalgesia could be inhibited by CNQX and dl-AP3 and contralateral mechanical hyperalgesia could be inhibited by APDC. On intrathecal injection of glutamate receptor antagonists/agonist after BmK venom injection by 4.5h, primary thermal hyperalgesia could be partially reversed by all tested agents, while bilateral mechanical hyperalgesia could only be inhibited by APDC. The results suggest that the role of spinal glutamate receptors may be different on the various manifestations of BmK venom-induced pain-related behaviors.
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Affiliation(s)
- Tong Liu
- Graduate School of the Chinese Academy of Sciences, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PR China
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Kitta T, Kakizaki H, Tanaka H, Sano H, Furuno T, Mitsui T, Moriya K, Nonomura K. An ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionate glutamate-receptor antagonist can inhibit premicturition contractions in rats with bladder outlet obstruction. BJU Int 2007; 100:181-6. [PMID: 17488306 DOI: 10.1111/j.1464-410x.2007.06919.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To explore the possible involvement of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) glutamate-receptors in bladder dysfunction associated with bladder outlet obstruction (BOO), as detrusor overactivity (DO) is common in men with benign prostatic hyperplasia. MATERIALS AND METHODS Proposed mechanisms of DO include the myogenic or neurogenic theory, and the autonomous bladder hypothesis. In rats, BOO produces premicturition contractions (PMCs) that are assumed to be a consequence of inappropriate non-micturition activity during the filling phase. Using pharmacology, we explored the cause of PMCs to provide new insights into DO in humans. BOO was created in female Wistar rats; 6 weeks after obstruction we evaluated them using conscious-filling cystometry. A specific AMPA receptor antagonist, 1-(4'-aminophenyl)- 3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one (CFM-2) was administered intravenously (i.v.) (0.003-3 mg/kg) or intrathecally (i.t.) (0.01-10 microg). RESULTS The i.v. administration of CFM-2 in rats with BOO significantly decreased the threshold pressure and micturition pressure. The most remarkable findings were that i.v. administration of CFM-2 in rats with BOO significantly and dose-dependently decreased the amplitude and number of PMCs. The highest dose of CFM-2 almost completely eliminated PMCs. The i.t. administration of CFM-2 had no significant effect on PMCs. CONCLUSION AMPA receptors have never been suggested as a neural mechanism of bladder dysfunction associated with BOO. Although PMCs in rats with BOO have been assumed to be mainly of myogenic origin, PMCs were suppressed by the i.v. administration of CFM-2. Thus, we think that PMCs have neurogenic components that are linked with AMPA receptors. In the present study, i.v. but not i.t. administration of CFM-2 suppressed PMCs, suggesting peripheral and/or supraspinal sites of inhibitory action of CFM-2 on PMCs.
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Affiliation(s)
- Takeya Kitta
- Department of Urology, Hokkaido University Graduate School of Medicine, North-15 West-7 Kita-Ku, Sapporo 060-8638, Japan.
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Chizh BA. Low dose ketamine: a therapeutic and research tool to explore N-methyl-D-aspartate (NMDA) receptor-mediated plasticity in pain pathways. J Psychopharmacol 2007; 21:259-71. [PMID: 17591654 DOI: 10.1177/0269881105062484] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ketamine is a dissociative anaesthetic that has been used in the clinic for many years. At low, sub-anaesthetic doses, it is a relatively selective and potent antagonist of the N-methyl-D-aspartate (NMDA) receptor. It belongs to the class of uncompetitive antagonists and blocks the receptor by binding to a specific site within the NMDA receptor channel when it is open. Like other compounds of this class, ketamine can cause hallucinations or other untoward central effects which limit its use in the clinic. Nevertheless, because of the evidence on the importance of NMDA receptor-mediated pLasticity in chronic pain, low doses of ketamine have been explored in a wide range of pain conditions. The majority of studies with ketamine have shown efficacy; however, it has not been possible to separate safely the pain relief from the side effects of the drug. Hence, clinical use of ketamine as a pain treatment is very limited. Nevertheless, ketamine has served as a useful tool to provide a compelling rationale for developing other NMDA antagonists. Some of the new compounds of this class, particularly those acting at the NR2B subtype of the NMDA receptor, have shown promise in preclinical and clinical studies.
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Affiliation(s)
- Boris A Chizh
- GlaxoSmithKline, Addenbrooke's Centre for Clinical Investigation, Addenbrooke's Hospital, Cambridge, UK.
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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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Gwak YS, Kang J, Leem JW, Hulsebosch CE. Spinal AMPA receptor inhibition attenuates mechanical allodynia and neuronal hyperexcitability following spinal cord injury in rats. J Neurosci Res 2007; 85:2352-9. [PMID: 17549753 DOI: 10.1002/jnr.21379] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this study, we examined whether a competitive AMPA receptor antagonist, NBQX, attenuates mechanical allodynia and hyperexcitability of spinal neurons in remote, caudal regions in persistent central neuropathic pain following spinal cord injury in rats. Spinal cord injury was produced by unilateral T13 transverse spinal hemisection, from dorsal to ventral, in male Sprague Dawley rats (200-250 g). Mechanical thresholds were measured behaviorally, and the excitability of wide-dynamic-range (WDR) dorsal horn neurons in the lumbar cord (L4-L5) was measured to assess central neuropathicpain. On postoperation day (POD) 28 after spinalhemisection, mechanical thresholds were significantly decreased in both injured (ipsilateral) and noninjured (contralateral) hindpaws compared with preinjury and sham control, respectively (P < 0.05). Intrathecal administration of NBQX (0.25, 0.5, 1 mM) significantly reversed the decreased mechanical thresholds in both hindpaws, dose dependently (P < 0.05). The excitability of WDR neurons was significantly enhanced on both sides of the lumbar dorsal horn 28 days following spinal hemisection (P < 0.05). The hyperexcitability of WDR neurons was attenuated by topical administration of NBQX (0.125, 0.25, 0.5, 1 mM), dose dependently (P < 0.05). Regression analysis indicated that at least three molecules of NBQX bond per receptor complex, and are needed to achieve inhibition of WDR hyperexcitability. In conclusion, our study demonstrates that the AMPA receptor plays an important role in behaviors related to the maintenance of central neuropathic pain below the level of spinal cord injury.
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Affiliation(s)
- Young Seob Gwak
- Department of Physiology, Brain Research Institute, and BK21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
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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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Park HJ, Lee Y, Lee J, Park C, Moon DE. The effects of botulinum toxin A on mechanical and cold allodynia in a rat model of neuropathic pain. Can J Anaesth 2006; 53:470-7. [PMID: 16636031 DOI: 10.1007/bf03022619] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
PURPOSE Botulinum toxin type A (BoNT-A) has been used to treat many disorders related to excessive muscle contraction, but there are few studies evaluating its effects on neuropathic pain. The aim of this study was to evaluate the analgesic effects of BoNT-A in a rat model of neuropathic pain. METHODS Male Sprague-Dawley rats were prepared by ligating the left L5 and L6 spinal nerves to produce neuropathic pain. Seventy neuropathic rats were randomly assigned into seven groups. Either normal saline or BoNT-A (10, 20, 30 and 40 U.kg(-1)) was administered to the plantar surface of the affected left hind paw, and BoNT-A (30 and 40 U.kg(-1)) was administered into the unaffected right paw in order to determine the drug-induced systemic effect. Mechanical and cold allodynia were observed at pre-administration, one, three, five, seven and 15 days after drug administration, and were quantified by measuring withdrawal frequencies to stimuli with von Frey filament and 100% acetone, respectively. Rotarod performance was measured to detect drug-induced adverse motor effects. RESULTS The mean minimum withdrawal frequencies to mechanical and cold stimuli were 77 +/- 11 and 90 +/- 4.5%, 46 +/- 5 and 66 +/- 7%, 33 +/- 7 and 62 +/- 7%, 12 +/- 2.9 and 54 +/- 7.3% with 10, 20, 30 and 40 U.kg(-1) BoNT-A respectively (P < 0.05). Doses of 30 and 40 U.kg(-1) BoNT-A resulted in reduced rotarod performance time. CONCLUSION We conclude that peripherally administered BoNT-A reduces mechanical and cold allodynia in a rat model of neuropathic pain.
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Affiliation(s)
- Hue Jung Park
- Department of Anesthesiology and Pain Medicine, School of Medicine, The Catholic University of Korea, Kangnam St. Mary's Hospital, 505 Banpo-Dong, Seocho-Gu, Seoul, Korea, 137-040
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