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Sadighparvar S, Al-Hamed FS, Sharif-Naeini R, Meloto CB. Preclinical orofacial pain assays and measures and chronic primary orofacial pain research: where we are and where we need to go. FRONTIERS IN PAIN RESEARCH 2023; 4:1150749. [PMID: 37293433 PMCID: PMC10244561 DOI: 10.3389/fpain.2023.1150749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/11/2023] [Indexed: 06/10/2023] Open
Abstract
Chronic primary orofacial pain (OFP) conditions such as painful temporomandibular disorders (pTMDs; i.e., myofascial pain and arthralgia), idiopathic trigeminal neuralgia (TN), and burning mouth syndrome (BMS) are seemingly idiopathic, but evidence support complex and multifactorial etiology and pathophysiology. Important fragments of this complex array of factors have been identified over the years largely with the help of preclinical studies. However, findings have yet to translate into better pain care for chronic OFP patients. The need to develop preclinical assays that better simulate the etiology, pathophysiology, and clinical symptoms of OFP patients and to assess OFP measures consistent with their clinical symptoms is a challenge that needs to be overcome to support this translation process. In this review, we describe rodent assays and OFP pain measures that can be used in support of chronic primary OFP research, in specific pTMDs, TN, and BMS. We discuss their suitability and limitations considering the current knowledge of the etiology and pathophysiology of these conditions and suggest possible future directions. Our goal is to foster the development of innovative animal models with greater translatability and potential to lead to better care for patients living with chronic primary OFP.
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Affiliation(s)
- Shirin Sadighparvar
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
- The Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
| | | | - Reza Sharif-Naeini
- The Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
- Department of Physiology and Cell Information Systems, McGill University, Montreal, QC, Canada
| | - Carolina Beraldo Meloto
- The Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, QC, Canada
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Liu J, Jia S, Huang F, He H, Fan W. Peripheral role of glutamate in orofacial pain. Front Neurosci 2022; 16:929136. [PMID: 36440288 PMCID: PMC9682037 DOI: 10.3389/fnins.2022.929136] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 10/10/2022] [Indexed: 09/10/2023] Open
Abstract
Glutamate is the principal excitatory neurotransmitter in the central nervous system. In the periphery, glutamate acts as a transmitter and involves in the signaling and processing of sensory input. Glutamate acts at several types of receptors and also interacts with other transmitters/mediators under various physiological and pathophysiological conditions including chronic pain. The increasing amount of evidence suggests that glutamate may play a role through multiple mechanisms in orofacial pain processing. In this study, we reviewed the current understanding of how peripheral glutamate mediates orofacial pain, how glutamate is regulated in the periphery, and how these findings are translated into therapies for pain conditions.
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Affiliation(s)
- Jinyue Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Shilin Jia
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Fang Huang
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Hongwen He
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Wenguo Fan
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
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Liu YJ, Li YL, Fang ZH, Liao HL, Zhang YY, Lin J, Liu F, Shen JF. NMDARs mediate peripheral and central sensitization contributing to chronic orofacial pain. Front Cell Neurosci 2022; 16:999509. [PMID: 36238833 PMCID: PMC9553029 DOI: 10.3389/fncel.2022.999509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/22/2022] [Indexed: 11/28/2022] Open
Abstract
Peripheral and central sensitizations of the trigeminal nervous system are the main mechanisms to promote the development and maintenance of chronic orofacial pain characterized by allodynia, hyperalgesia, and ectopic pain after trigeminal nerve injury or inflammation. Although the pathomechanisms of chronic orofacial pain are complex and not well known, sufficient clinical and preclinical evidence supports the contribution of the N-methyl-D-aspartate receptors (NMDARs, a subclass of ionotropic glutamate receptors) to the trigeminal nociceptive signal processing pathway under various pathological conditions. NMDARs not only have been implicated as a potential mediator of pain-related neuroplasticity in the peripheral nervous system (PNS) but also mediate excitatory synaptic transmission and synaptic plasticity in the central nervous system (CNS). In this review, we focus on the pivotal roles and mechanisms of NMDARs in the trigeminal nervous system under orofacial neuropathic and inflammatory pain. In particular, we summarize the types, components, and distribution of NMDARs in the trigeminal nervous system. Besides, we discuss the regulatory roles of neuron-nonneuronal cell/neuron-neuron communication mediated by NMDARs in the peripheral mechanisms of chronic orofacial pain following neuropathic injury and inflammation. Furthermore, we review the functional roles and mechanisms of NMDARs in the ascending and descending circuits under orofacial neuropathic and inflammatory pain conditions, which contribute to the central sensitization. These findings are not only relevant to understanding the underlying mechanisms, but also shed new light on the targeted therapy of chronic orofacial pain.
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Affiliation(s)
- Ya-Jing Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yue-Ling Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Zhong-Han Fang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hong-Lin Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yan-Yan Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiu Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Fei Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Jie-Fei Shen Fei Liu
| | - Jie-Fei Shen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, National Center for Stomatology, West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Jie-Fei Shen Fei Liu
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Zhu YF, Linher-Melville K, Wu J, Fazzari J, Miladinovic T, Ungard R, Zhu KL, Singh G. Bone cancer-induced pain is associated with glutamate signalling in peripheral sensory neurons. Mol Pain 2021; 16:1744806920911536. [PMID: 32133928 PMCID: PMC7059229 DOI: 10.1177/1744806920911536] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We previously identified that several cancer cell lines known to induce
nociception in mouse models release glutamate in vitro. Although the mechanisms
of glutamatergic signalling have been characterized primarily in the central
nervous system, its importance in the peripheral nervous system has been
recognized in various pathologies, including cancer pain. We therefore
investigated the effect of glutamate on intracellular electrophysiological
characteristics of peripheral sensory neurons in an immunocompetent rat model of
cancer-induced pain based on surgical implantation of mammary rat metastasis
tumour-1 cells into the distal epiphysis of the right femur. Behavioural
evidence of nociception was detected using von Frey tactile assessment. Activity
of sensory neurons was measured by intracellular electrophysiological recordings
in vivo. Glutamate receptor expression at the mRNA level in relevant dorsal root
ganglia was determined by reverse transcription polymerase chain reaction using
rat-specific primers. Nociceptive and non-nociceptive mechanoreceptor neurons
exhibiting changes in neural firing patterns associated with increased
nociception due to the presence of a bone tumour rapidly responded to
sulphasalazine injection, an agent that pharmacologically blocks non-vesicular
glutamate release by inhibiting the activity of the system
xC− antiporter. In addition, both types of
mechanoreceptor neurons demonstrated excitation in response to intramuscular
glutamate injection near the femoral head, which corresponds to the location of
cancer cell injection to induce the bone cancer-induced pain model. Therefore,
glutamatergic signalling contributes to cancer pain and may be a factor in
peripheral sensitization and induced tactile hypersensitivity associated with
bone cancer-induced pain.
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Affiliation(s)
- Yong Fang Zhu
- Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Katja Linher-Melville
- Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jianhan Wu
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Jennifer Fazzari
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Tanya Miladinovic
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Robert Ungard
- Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Kan Lun Zhu
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
| | - Gurmit Singh
- Michael G. DeGroote Institute for Pain Research and Care, McMaster University, Hamilton, ON, Canada.,Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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Chung MK, Ro JY. Peripheral glutamate receptor and transient receptor potential channel mechanisms of craniofacial muscle pain. Mol Pain 2021; 16:1744806920914204. [PMID: 32189565 PMCID: PMC7153498 DOI: 10.1177/1744806920914204] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Temporomandibular joint disorder is a common chronic craniofacial pain condition,
often involving persistent, widespread craniofacial muscle pain. Although the
etiology of chronic muscle pain is not well known, sufficient clinical and
preclinical information supports a contribution of trigeminal nociceptors to
craniofacial muscle pain processing under various experimental and pathological
conditions. Here, we review cellular and molecular mechanisms underlying
sensitization of muscle nociceptive afferents. In particular, we summarize
findings on pronociceptive roles of peripheral glutamate in humans, and we
discuss mechanistic contributions of glutamate receptors, including
N-methyl-D-aspartate receptors and metabotropic glutamate receptors, which have
considerably increased our understanding of peripheral mechanisms of
craniofacial muscle pain. Several members of the transient receptor potential
(TRP) family, such as transient receptor potential vanilloid 1 (TRPV1) and
transient receptor potential ankyrin 1, also play essential roles in the
development of spontaneous pain and mechanical hypersensitivity in craniofacial
muscles. Furthermore, glutamate receptors and TRP channels functionally and
bi-directionally interact to modulate trigeminal nociceptors. Activation of
glutamate receptors invokes protein kinase C, which leads to the phosphorylation
of TRPV1. Sensitization of TRPV1 by inflammatory mediators and glutamate
receptors in combination with endogenous ligands contributes to masseter
hyperalgesia. The distinct intracellular signaling pathways through which both
receptor systems engage and specific molecular regions of TRPV1 are offered as
novel targets for the development of mechanism-based treatment strategies for
myogenous craniofacial pain conditions.
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Affiliation(s)
- Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
| | - Jin Y Ro
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, The University of Maryland, Baltimore, MD, USA
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Cho YS, Ryu CH, Won JH, Vang H, Oh SB, Ro JY, Bae YC. Rat odontoblasts may use glutamate to signal dentin injury. Neuroscience 2016; 335:54-63. [PMID: 27555550 DOI: 10.1016/j.neuroscience.2016.08.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 08/13/2016] [Accepted: 08/16/2016] [Indexed: 10/21/2022]
Abstract
Accumulating evidence indicates that odontoblasts act as sensor cells, capable of triggering action potentials in adjacent pulpal nociceptive axons, suggesting a paracrine signaling via a currently unknown mediator. Since glutamate can mediate signaling by non-neuronal cells, and peripheral axons may express glutamate receptors (GluR), we hypothesized that the expression of high levels of glutamate, and of sensory receptors in odontoblasts, combined with an expression of GluR in adjacent pulpal axons, is the morphological basis for odontoblastic sensory signaling. To test this hypothesis, we investigated the expression of glutamate, the thermo- and mechanosensitive ion channels transient receptor potential vanilloid 1 (TRPV1), transient receptor potential ankyrin 1 (TRPA1), and TWIK-1-related K+channel (TREK-1), and the glutamate receptor mGluR5, in a normal rat dental pulp, and following dentin injury. We also examined the glutamate release from odontoblast in cell culture. Odontoblasts were enriched with glutamate, at the level as high as in adjacent pulpal axons, and showed immunoreactivity for TRPV1, TRPA1, and TREK-1. Pulpal sensory axons adjacent to odontoblasts expressed mGluR5. Both the levels of glutamate in odontoblasts, and the expression of mGluR5 in nearby axons, were upregulated following dentin injury. The extracellular glutamate concentration was increased significantly after treating of odontoblast cell line with calcium permeable ionophore, suggesting glutamate release from odontoblasts. These findings lend morphological support to the hypothesis that odontoblasts contain glutamate as a potential neuroactive substance that may activate adjacent pulpal axons, and thus contribute to dental pain and hypersensitivity.
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Affiliation(s)
- Yi Sul Cho
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Chang Hyun Ryu
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Jong Hwa Won
- Pain Cognitive Function Research Center, Dental Research Institute of Neurobiology and Physiology, School of Dentistry, Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hue Vang
- Pain Cognitive Function Research Center, Dental Research Institute of Neurobiology and Physiology, School of Dentistry, Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Seog Bae Oh
- Pain Cognitive Function Research Center, Dental Research Institute of Neurobiology and Physiology, School of Dentistry, Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jin Young Ro
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, USA
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea.
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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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Blockade of glutamate release by botulinum neurotoxin type A in humans: a dermal microdialysis study. Pain Res Manag 2015; 19:126-32. [PMID: 24851237 DOI: 10.1155/2014/410415] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND The analgesic action of botulinum neurotoxin type A (BoNTA) has been linked to the blockade of peripheral release of neuropeptides and neurotransmitters in animal models; however, there is no direct evidence of this in humans. OBJECTIVES To investigate the effect of BoNTA on glutamate release in humans, using an experimental model of pain and sensitization provoked by capsaicin plus mild heat. METHODS Twelve healthy volunteers (six men, six women) were pretreated with BoNTA (10 U) on the volar forearm and with a saline control on the contralateral side. Dermal microdialysis was applied one week later to collect interstitial samples before and after the application of a capsaicin patch (8%) plus mild heat (40°C⁄60 min) to provoke glutamate release, pain and vasodilation. Samples were collected every hour for 3 h using linear microdialysis probes (10 mm, 100 kD). Dialysate was analyzed for glutamate concentration. Pain intensity and skin vasomotor reactions (temperature and blood flow changes) were also recorded. RESULTS BoNTA significantly reduced glutamate release compared with saline (P<0.05). The provoked pain intensity was lower in the BoNTA-pretreated arm (P<0.01). The reduction in pain scores was not correlated with glutamate level. Cutaneous blood flow (P<0.05), but not cutaneous temperature (P≥0.05), was significantly reduced by BoNTA. There was a correlation between glutamate level and skin blood flow (r=0.58⁄P<0.05) but not skin temperature (P≥0.05). No differences according to sex were observed in any response. CONCLUSIONS The present study provided the first direct evidence supporting the inhibitory effect of BoNTA on glutamate release in human skin, which is potentially responsible for some of the analgesic action of BoNTA.
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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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10
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Sánchez EM, Bagües A, Martín MI. Contributions of peripheral and central opioid receptors to antinociception in rat muscle pain models. Pharmacol Biochem Behav 2010; 96:488-95. [PMID: 20637793 DOI: 10.1016/j.pbb.2010.07.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/17/2010] [Accepted: 07/09/2010] [Indexed: 11/18/2022]
Abstract
Administration of hypertonic saline (HS) is an accepted model to study muscular pain. HS-induced nociceptive responses were tested in masseter, already described, and in two new pain models of spinally innervated muscles (gastrocnemius and triceps) developed in rats at our laboratory. HS administration in the masseter induced vigorous hindpaw shaking and in the gastrocnemius or triceps, paw withdrawal or flexing. Participation of the central and peripheral opioid receptors in HS-induced pain is compared in these muscles: masseter, innervated by trigeminal nerve, and gastrocnemius and triceps by spinal nerves. Morphine and loperamide were used to reveal peripheral and central components of opioid analgesia. Both agonists reduced HS-induced nociceptive behaviours in the masseter and were antagonised by the opioid antagonist naloxone and by naloxone methiodide, an opioid receptor antagonist that poorly penetrates the blood-brain barrier. Unexpectedly, in the gastrocnemius and triceps, morphine, but not loperamide, decreased the nociceptive behaviour and this effect was only reversed by naloxone. So, peripheral opioid receptors seem to participate in HS-induced masseter pain, whereas only central opioid receptors reduced the nociception in gastrocnemius and triceps. Our results suggest that the use of peripheral opioids can be more advantageous than central opioids for treatment of orofacial muscular pain.
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Affiliation(s)
- Eva Ma Sánchez
- Departamento de Farmacología y Nutrición, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Madrid, Spain.
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11
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Chun YH, Ro JY. Electrophysiological characterization of the rat trigeminal caudalis (Vc) neurons following intramuscular injection of capsaicin. Neurosci Lett 2009; 469:289-93. [PMID: 19818833 DOI: 10.1016/j.neulet.2009.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 09/28/2009] [Accepted: 10/04/2009] [Indexed: 12/01/2022]
Abstract
Extracellular single unit recording experiments were performed to examine response characteristics of wide dynamic range neurons in the Vc that receive masseter afferent input in Sprague-Dawley rats. Capsaicin, or its vehicle, was directly administered into the masseter muscle and changes in resting discharge, responses to mechanical stimulation on the cutaneous receptive field and the electrical threshold for masseter nerve stimulation were assessed. Intramuscular capsaicin induced significant increase in the background discharge and mechanical hypersensitivity to the cutaneous stimulation and lowered the threshold for masseter nerve stimulation-evoked responses in the majority of neurons. The capsaicin-induced increase in evoked responses, but not the resting discharge, was partially attenuated when the muscle was pretreated with a mGluR antagonist. The present study suggests that injury or inflammation in the masseter muscle induce generalized hyperexcitability of central trigeminal neurons and that the blockade of peripherally localized mGluR5 can effectively attenuate muscular hypersensitivity.
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Affiliation(s)
- Yang H Chun
- Kyung Hee University, School of Dentistry, Department of Oral Medicine, 1 Hoegi Dong, DongdaemunGu, Seoul, Republic of Korea
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12
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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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13
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Han SR, Lee MK, Lim KH, Yang GY, Jeon HJ, Ju JS, Yoon YW, Kim SK, Ahn DK. Intramuscular administration of morphine reduces mustard-oil-induced craniofacial-muscle pain behavior in lightly anesthetized rats. Eur J Pain 2007; 12:361-70. [PMID: 17768078 DOI: 10.1016/j.ejpain.2007.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 07/04/2007] [Accepted: 07/09/2007] [Indexed: 10/22/2022]
Abstract
The present study investigated the role of peripheral opioid receptors in mustard oil-induced nociceptive behavior and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing between 300 and 400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for the intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 microl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle. Intramuscularly-administered morphine significantly reduced shaking behavior but not MO-induced inflammation. Intramuscular pretreatment with naloxone, an opioid receptor antagonist, reversed antinociception produced by intramuscularly-administered morphine, while intracisternal administration of naloxone did not affect the antinociception of peripheral morphine. Pretreatment with d-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), a mu opioid receptor antagonist, but not naltrindole, a delta opioid receptor antagonist, nor norbinaltorphimine (nor-BNI), a kappa opioid receptor antagonist, reversed intramuscularly-administered morphine-induced antinociception. These results indicate that intramuscularly-administered morphine produces antinociception in craniofacial muscle nociception and that this intramuscularly-administered morphine-induced antinociception is mediated by a peripheral mu opioid receptor. Our observations further support the clinical approach of administering opioids in the periphery for the treatment of craniofacial muscle nociception.
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Affiliation(s)
- Seung R Han
- Department of Oral Physiology and BrainKorea 21, School of Dentistry, Kyungpook National University, 188-1, SamDeok 2ga, Chung-gu, Daegu 700-412, Republic of Korea
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14
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Lee J, Ro JY. Differential regulation of glutamate receptors in trigeminal ganglia following masseter inflammation. Neurosci Lett 2007; 421:91-5. [PMID: 17560028 PMCID: PMC2956190 DOI: 10.1016/j.neulet.2007.05.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Revised: 05/17/2007] [Accepted: 05/18/2007] [Indexed: 01/23/2023]
Abstract
The present study examined whether N-methyl-D-aspartate receptor (NMDAR), 5-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits and group I metabotropic glutamate receptors (mGluRs) are constitutively expressed in trigeminal ganglia (TG) using Western blot analysis in male Sprague-Dawley rats. We then investigated whether experimental induction of masseter inflammation influences glutamate receptor expressions by comparing the protein levels from naïve rats to those from complete Freund's adjuvant (CFA) inflamed rats. Our results showed that NMDAR1 (NR1), NMDAR2A (NR2A), NMDAR2B (NR2B), AMPAR1 (GluR1) and AMPAR2 (GluR2) subunits, and group I metabotropic glutamate receptor, mGluR5, are constitutively expressed in TG. Masseter inflammation significantly down-regulated NR1 subunit expression that persisted to 7 days post-CFA inflammation. NR2A and NR2B expressions were not significantly changed. GluR1 receptor subunit expression was slightly increased in TG 3 days after CFA-induced inflammation, but the change was not statistically significant. GluR2 protein level was not affected by CFA inflammation. The level of mGluR5 protein was significantly up-regulated in TG 3 days after CFA-induced masseter inflammation. There were no inflammation-induced changes in any of the proteins we analyzed in the contralateral, non-inflamed TG. These results suggested that muscle inflammation differentially modulates glutamate receptor subunits at the primary afferent level in male rats and that these inflammation-induced transcriptional changes may contribute to functionally different aspects of craniofacial muscle pain.
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Affiliation(s)
- Jongseok Lee
- Department of Biomedical Sciences, Program in Neuroscience, University of Maryland Baltimore, School of Dentistry, 650 W. Baltimore Street, Baltimore, Maryland 21201, USA
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15
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Dong XD, Mann MK, Kumar U, Svensson P, Arendt-Nielsen L, Hu JW, Sessle BJ, Cairns BE. Sex-related differences in NMDA-evoked rat masseter muscle afferent discharge result from estrogen-mediated modulation of peripheral NMDA receptor activity. Neuroscience 2007; 146:822-32. [PMID: 17382479 PMCID: PMC1976542 DOI: 10.1016/j.neuroscience.2007.01.051] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 01/25/2007] [Accepted: 01/30/2007] [Indexed: 10/23/2022]
Abstract
In the present study, the hypothesis that sex-related differences in glutamate-evoked rat masseter muscle afferent discharge may result from estrogen-related modulation of peripheral N-methyl-d-aspartate (NMDA) receptor activity and/or expression was tested by examining afferent fiber discharge in response to masseter injection of NMDA and the expression of NR2A/B subunits by masseter ganglion neurons in male and female rats. The results showed that injection of NMDA into the masseter muscle evoked discharges in putative mechanonociceptive afferent fibers and increased blood pressure that was concentration-dependent, however, a systemic action of NMDA appeared responsible for increased blood pressure. NMDA-evoked afferent discharge was significantly greater in female than in male rats, was positively correlated with plasma estrogen levels in females and was significantly greater in ovariectomized female rats treated with a high dose (5 mug/day) compared with a low dose (0.5 mug/day) of estrogen. Pre-treatment of high dose estrogen-treated-ovariectomized female rats with the Src tyrosine kinase inhibitor PP2 did not affect NMDA-evoked afferent discharge. NMDA-evoked afferent discharge was attenuated by the antagonists ketamine and ifenprodil, which is selective for NR2B containing NMDA receptors. Fewer masseter ganglion neurons expressed the NR2A (16%) subunit as compared with the NR2B subunit (38%), which was expressed at higher frequencies in intact female (46%) and high dose estrogen-treated ovariectomized female (60%) rats than in male (31%) rats. Taken together, these results suggest that sex-related differences in NMDA-evoked masseter afferent discharge are due, at least in part, to an estrogen-mediated increase in expression of peripheral NMDA receptors by masseter ganglion neurons in female rats.
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Affiliation(s)
- Xu-Dong Dong
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Mandeep K. Mann
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Ujendra Kumar
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Peter Svensson
- Department of Clinical Oral Physiology, Dental School, Århus University, DK-8000 Århus C, Denmark
| | - Lars Arendt-Nielsen
- Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, DK-9220, Denmark
| | - James W. Hu
- Faculty of Dentistry, The University of Toronto, Toronto, Ontario, M5G 1G6 Canada
| | - Barry J. Sessle
- Faculty of Dentistry, The University of Toronto, Toronto, Ontario, M5G 1G6 Canada
| | - Brian E. Cairns
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
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16
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Lee JS, Ro JY. Peripheral metabotropic glutamate receptor 5 mediates mechanical hypersensitivity in craniofacial muscle via protein kinase C dependent mechanisms. Neuroscience 2007; 146:375-83. [PMID: 17306466 DOI: 10.1016/j.neuroscience.2007.01.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 01/08/2007] [Accepted: 01/12/2007] [Indexed: 11/27/2022]
Abstract
We previously demonstrated that peripherally located N-methyl-D-aspartic acid (NMDA) receptors contribute to acute muscle nociception and the development of chronic muscular hyperalgesia. In the present study, we investigated the potential role of peripheral group I metabotropic glutamate receptors (mGluRs 1/5) in the development of muscular hypersensitivity to mechanical stimulation, and attempted to elucidate intracellular signaling mechanisms associated with the mGluR activation in male Sprague-Dawley rats. First, our Western blot analyses revealed that mGluR 5 protein, but not mGluR 1 protein, is reliably detected in trigeminal ganglia and the masseter nerve. Subsequent behavioral studies demonstrated that the group I mGluR agonist, R,S-3,5-dihydroxyphenylglycol (DHPG), significantly decreased the mechanical threshold to noxious stimulation of the masseter, and that the DHPG-induced mechanical hypersensitivity can be effectively prevented by pretreatment of the masseter with 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), a selective mGluR 5 antagonist, but not by 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt), a selective mGluR 1 antagonist. Moreover, the DHPG-induced mechanical hypersensitivity was significantly blocked by inhibiting either the alpha or epsilon isoform of protein kinase C (PKC). Collectively, these data provide evidence that peripherally located mGluR 5 may play an important role in the development of masseter hypersensitivity, and that PKC activation is required for the modulatory effect of peripheral mGluR 5 in the craniofacial muscle tissue. Thus, selective targeting of peripheral mGluR 5 and PKCalpha, as well as PKCepsilon, might serve as an effective therapeutic strategy in the management of chronic muscle pain conditions, such as temporomandibular disorders.
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Affiliation(s)
- J-S Lee
- Department of Biomedical Sciences, Program in Neuroscience, University of Maryland Baltimore School of Dentistry, 650 West Baltimore Street, Baltimore, MD 21201, USA
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17
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Gazerani P, Wang K, Cairns BE, Svensson P, Arendt-Nielsen L. Effects of subcutaneous administration of glutamate on pain, sensitization and vasomotor responses in healthy men and women. Pain 2006; 124:338-348. [PMID: 16919390 DOI: 10.1016/j.pain.2006.06.015] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Revised: 06/06/2006] [Accepted: 06/09/2006] [Indexed: 10/24/2022]
Abstract
The present study aimed to investigate if (1) subcutaneous injection of glutamate induces pain, sensitization and vasomotor responses in humans and (2) if sex differences exist in these responses. Thirty healthy volunteers (men-15 and women-15) were included. Each subject received four subcutaneous injections (0.1ml; glutamate 100, 10, 1mM and isotonic saline 0.9%) into the forehead skin in two sessions separated by one week. Assessments of pain intensity (VAS), quality, distribution; area of pinprick hyperalgesia; pressure pain threshold (PPT) at the injection site; surface skin temperature and local blood flow were performed at predetermined time points. The highest concentration of glutamate evoked the highest pain intensity, the longest duration of pain and the largest pain area under the VAS-time curve (P<0.001) in both men and women, although responses in women were larger than in men (P<0.05). The face-chart pain area was the largest for the highest concentration of glutamate (P<0.001) and women drew a larger pain area than men (P=0.024). The area of pinprick hyperalgesia was the largest for glutamate 100mM (P<0.001) and women indicated a larger area than men (P<0.001). Concentration-dependent local vasomotor responses were found following the subcutaneous injection of glutamate but there was no sex difference in this effect. Glutamate 100mM significantly reduced the PPT values (P<0.001) without sex-related differences. The present study demonstrates for the first time that subcutaneous injection of glutamate evokes pain, vasomotor responses and pinprick hyperalgesia in human volunteers and that there are sex-related differences in some of these responses.
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Affiliation(s)
- Parisa Gazerani
- Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, 9220 Aalborg, Denmark Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, V6T 1Z3 Vancouver, Canada Department of Clinical Oral Physiology, School of Dentistry, Aarhus University, 8000 Aarhus C, Denmark
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18
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Ro JY, Capra NF, Lee JS, Masri R, Chun YH. Hypertonic saline-induced muscle nociception and c-fos activation are partially mediated by peripheral NMDA receptors. Eur J Pain 2006; 11:398-405. [PMID: 16872852 DOI: 10.1016/j.ejpain.2006.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 04/10/2006] [Accepted: 05/14/2006] [Indexed: 11/17/2022]
Abstract
In this study, the animal model of hypertonic saline (HS) infusion protocol was developed and utilized to test the hypothesis that HS causes peripheral release of glutamate, and that blockade of peripheral NMDA receptors significantly reduces HS-induced nocifensive behavior and central neuronal activation. Nocifensive behavior and c-fos immunoreactivity, as a marker of central neuronal activation, were assessed from the animals that received intramuscular HS infusion with and without the NMDA receptor antagonist, MK-801. HS infusion (20 microl/min for 10 min) in the rat masseter produced prolonged nocifensive hindpaw shaking responses that peaked in the first minute and gradually diminished over the infusion period. The HS induced nocifensive behavior was dose-dependently attenuated by MK-801 pretreatments (0.3 mg/kg and 0.1 mg/kg), but not by vehicle pretreatment (isotonic saline; ISO), in the masseter muscle. HS infusion produced a significant number of Fos positive neurons in the ispsilateral subnucleus caudalis (Vc). Subsequent immunohistochemical studies showed that peripheral MK-801 pretreatment effectively reduced the HS induced neuronal activation in the Vc. These results provide compelling evidence that HS-induced muscle nociception is mediated, in part, by peripheral release of glutamate, and that blockade of peripheral glutamate receptors may provide effective means of preventing central neuronal activation.
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Affiliation(s)
- Jin Y Ro
- University of Maryland Baltimore, School of Dentistry, Department of Biomedical Sciences, 666 W. Baltimore Street, Baltimore, MD 21201, USA.
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19
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Lee HJ, Choi HS, Ju JS, Bae YC, Kim SK, Yoon YW, Ahn DK. Peripheral mGluR5 antagonist attenuated craniofacial muscle pain and inflammation but not mGluR1 antagonist in lightly anesthetized rats. Brain Res Bull 2006; 70:378-85. [PMID: 17027773 DOI: 10.1016/j.brainresbull.2005.09.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 07/27/2005] [Accepted: 09/06/2005] [Indexed: 01/02/2023]
Abstract
The present study investigated the role of peripheral group I metabotropic glutamate receptors (mGluRs) in MO-induced nociceptive behaviour and inflammation in the masseter muscles of lightly anesthetized rats. Experiments were carried out on male Sprague-Dawley rats weighing 300-400 g. After initial anesthesia with sodium pentobarbital (40 mg/kg, i.p.), one femoral vein was cannulated and connected to an infusion pump for intravenous infusion of sodium pentobarbital. The rate of infusion was adjusted to provide a constant level of anesthesia. Mustard oil (MO, 30 microl) was injected into the mid-region of the left masseter muscle via a 30-gauge needle over 10s. After 30 microl injection of 5, 10, 15, or 20% MO into the masseter muscle, the total number of hindpaw shaking behaviour and extravasated Evans' blue dye concentration in the masseter muscle were significantly higher in the MO-treated group in a dose-dependent manner compared with the vehicle (mineral oil)-treated group. Intramuscular pretreatment with 3 or 5% lidocaine reduced MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration. Intramuscular pretreatment with 5 mM MCPG, non-selective group I/II mGluR antagonist, or MPEP, a selective group I mGluR5 antagonist, produced a significant attenuation of MO-induced hindpaw shaking behaviour and increases in extravasated Evans' blue dye concentration in the masseter muscle while LY367385, a selective group I mGluR1 antagonist, did not affect MO-induced nociceptive behaviour and inflammation in the masseter muscle. These results indicate that peripheral mGluR5 plays important role in mediating MO-induced nociceptive behaviour and inflammation in the craniofacial muscle.
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Affiliation(s)
- Ho Jeong Lee
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea
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20
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Dong XD, Mann MK, Sessle BJ, Arendt-Nielsen L, Svensson P, Cairns BE. Sensitivity of rat temporalis muscle afferent fibers to peripheral N-methyl-D-aspartate receptor activation. Neuroscience 2006; 141:939-945. [PMID: 16716525 DOI: 10.1016/j.neuroscience.2006.04.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 04/14/2006] [Accepted: 04/18/2006] [Indexed: 11/28/2022]
Abstract
The temporalis muscle is a common source of pain in headache and chronic craniofacial pain conditions such as temporomandibular disorders, which have an increased prevalence in women. The characteristics of slowly conducting temporalis afferent fibers have not been investigated. Therefore, the aim of the present study was to examine the characteristics of slowly conducting temporalis muscle afferent fibers and to determine whether these fibers are excited by activation of peripheral N-methyl-D-aspartate receptors. The response properties of a total of 117 temporalis afferent fibers were assessed in male and female rats. A majority of these fibers had high mechanical thresholds and slow conduction velocities (<10 m/s). The mechanical threshold of the temporalis afferent fibers was inversely correlated with afferent conduction velocity, however, no sex-related differences in mechanical threshold were identified. There were also no sex-related differences in N-methyl-D-aspartate-evoked afferent discharge. Indeed, injection of a high concentration (1600 mM) of N-methyl-D-aspartate into the temporalis muscle was necessary to evoke significant afferent discharge. Thirty minutes after the initial injection of N-methyl-D-aspartate into the temporalis muscle, a second injection of N-methyl-D-aspartate produced a response only about 50% as large as the initial injection. Co-injection of ketamine (20 mM) with the second injection of N-methyl-D-aspartate significantly decreased N-methyl-D-aspartate-evoked afferent discharge in both sexes. This concentration of ketamine is greater than that needed to attenuate afferent discharge evoked by injection of glutamate into the masseter muscle. These results suggest that unlike masseter afferent fibers, temporalis afferent fibers are relatively insensitive to peripheral N-methyl-D-aspartate receptor activation.
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Affiliation(s)
- X D Dong
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - M K Mann
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, British Columbia, Canada V6T 1Z3
| | - B J Sessle
- Faculty of Dentistry, The University of Toronto, Toronto, Ontario, Canada M5G 1G6
| | - L Arendt-Nielsen
- Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, DK-9220 Aalborg, Denmark
| | - P Svensson
- Department of Clinical Oral Physiology, Dental School, Århus University, DK-8000 Århus C, Denmark
| | - B E Cairns
- Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, British Columbia, Canada V6T 1Z3.
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21
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Abstract
The present study demonstrates that intramuscular administration of N-methyl-D-aspartate receptor antagonist AP5 dose-dependently attenuates complete Freund's adjuvant (CFA) induced muscular hyperalgesia. CFA significantly reduced mean bite force and success rate in the rats trained to produce a specific bite force. Pretreatment with AP5 reversed the overall magnitude of reduction in mean bite force and success rate in CFA inflamed rats, and significantly facilitated the recovery of these measures to pre-injection level. AP5 treatment 1 day after the CFA injection had little effect on CFA-mediated changes in bite force measurements. These data suggest that peripheral N-methyl-D-aspartate receptors play a critical role in the development of persistent muscle hyperalgesia, and provide important new insights for therapeutic alternatives that can be directed at the periphery.
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Affiliation(s)
- Jin Y Ro
- Department of Biomedical Sciences, University of Maryland Baltimore School of Dentistry, Baltimore, MD 21201, USA.
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22
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Ro JY, Zhang Y, Nies M. Substance P does not play a critical role in neurogenic inflammation in the rat masseter muscle. Brain Res 2005; 1047:38-44. [PMID: 15885663 DOI: 10.1016/j.brainres.2005.04.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 03/23/2005] [Accepted: 04/01/2005] [Indexed: 10/25/2022]
Abstract
In this study, we performed a series of experiments to investigate whether substance P (SP) contributes to neurogenic inflammation in the skeletal muscle tissue. Intramuscular injection of an inflammatory irritant, mustard oil (MO), induces significant edema formation in the rat masseter muscle. In order to study the contribution of endogenous SP in the MO-induced edema, groups of rats were pretreated with two different doses (100 nmol; 1 microl) of either peptidergic (Sendide) or non-peptidergic (L703, 606) neurokinin 1 (NK1) receptor antagonist in one masseter muscle 15 min prior to the MO injection in the same muscle. The extent of edema was assessed as the percent weight difference of the injected muscle compared to the non-injected muscle. Neither Sendide nor L703,606 pretreatment resulted in a significant inhibition of the MO-induced edema in the masseter muscle. Exogenous application of SP also produced a significant swelling of the muscle, which was blocked by L703,606 (1 microl) pretreatment, suggesting that evoked release of SP following MO injection is not sufficient to induce significant edema formation. Capsaicin (1% in 25 microl), which is known to cause neurogenic inflammation, failed to produce edema formation in the masseter muscle. The same concentration of capsaicin injected into the hindpaw produced significant swelling of the injected paw. Taken together, these results provide compelling evidence that, unlike cutaneous or joint tissue, SP does not play a critical role in inducing neurogenic inflammation in the skeletal muscle tissue.
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Affiliation(s)
- Jin Y Ro
- Department of Biomedical Sciences, University of Maryland Baltimore School of Dentistry, 666 W. Baltimore Street, Baltimore, MD 21201, USA.
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23
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Ge HY, Madeleine P, Arendt-Nielsen L. Gender differences in pain modulation evoked by repeated injections of glutamate into the human trapezius muscle. Pain 2005; 113:134-40. [PMID: 15621373 DOI: 10.1016/j.pain.2004.09.041] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Revised: 09/30/2004] [Accepted: 09/30/2004] [Indexed: 11/16/2022]
Abstract
Gender differences in pain habituation, temporal summation, and pressure hyperalgesia evoked by repeated injections of glutamate into the dominant trapezius muscle were investigated. The glutamate-evoked muscle pain intensity and pressure pain threshold (PPT) were assessed. The PPTs were measured bilaterally in the trapezius muscles (local pain area) and posterolateral neck muscles (referred pain area) after glutamate injection in healthy and age-matched males and females (each n=14). Two glutamate injections (0.4 ml, 2M each) were injected with an interval of 5 min. One injection of glutamate (0.4 ml, 2M) served as a control. Males, but not females, rated the second injection (maximal pain intensity) significantly less painful than the first injection. The area under the visual analogue scale pain curve of the second injection was significantly larger than the first injection in females. Repeated glutamate injections, but not one-glutamate injection, significantly decreased PPTs in the local pain area, with no significant gender differences. No PPTs changes were observed either in the contralateral trapezius muscle or bilaterally in the referred pain areas in either sex. These results suggest that a less efficient pain habituation and a greater susceptibility to the development of temporal summation of muscle pain in females, but not in males, might be one of the contributing factors to the higher incidence of neck shoulder pain in females. In addition, the reduction of PPTs in the local pain area evoked by intramuscular glutamate injection may represent an early process of peripheral pressure hyperalgesia, which is most likely gender independent.
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Affiliation(s)
- Hong-You Ge
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg DK-9220, Denmark
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24
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Capra NF, Ro JY. Human and animal experimental models of acute and chronic muscle pain: intramuscular algesic injection. Pain 2004; 110:3-7. [PMID: 15275745 DOI: 10.1016/j.pain.2004.04.033] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Accepted: 04/23/2004] [Indexed: 11/29/2022]
Affiliation(s)
- Norman F Capra
- Department of Biomedical Sciences, University of Maryland Baltimore School of Dentistry, 666 W. Baltimore Street, Baltimore, MD 21201, USA.
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