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Nociceptor-localized cGMP-dependent protein kinase I is a critical generator for central sensitization and neuropathic pain. Pain 2021; 162:135-151. [PMID: 32773598 DOI: 10.1097/j.pain.0000000000002013] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Patients with neuropathic pain often experience exaggerated pain and anxiety. Central sensitization has been linked with the maintenance of neuropathic pain and may become an autonomous pain generator. Conversely, emerging evidence accumulated that central sensitization is initiated and maintained by ongoing nociceptive primary afferent inputs. However, it remains elusive what mechanisms underlie this phenomenon and which peripheral candidate contributes to central sensitization that accounts for pain hypersensitivity and pain-related anxiety. Previous studies have implicated peripherally localized cGMP-dependent protein kinase I (PKG-I) in plasticity of nociceptors and spinal synaptic transmission as well as inflammatory hyperalgesia. However, whether peripheral PKG-I contributes to cortical plasticity and hence maintains nerve injury-induced pain hypersensitivity and anxiety is unknown. Here, we demonstrated significant upregulation of PKG-I in ipsilateral L3 dorsal root ganglia (DRG), no change in L4 DRG, and downregulation in L5 DRG upon spared nerve injury. Genetic ablation of PKG-I specifically in nociceptors or post-treatment with intervertebral foramen injection of PKG-I antagonist, KT5823, attenuated the development and maintenance of spared nerve injury-induced bilateral pain hypersensitivity and anxiety. Mechanistic analysis revealed that activation of PKG-I in nociceptors is responsible for synaptic potentiation in the anterior cingulate cortex upon peripheral neuropathy through presynaptic mechanisms involving brain-derived neurotropic factor signaling. Our results revealed that PKG-I expressed in nociceptors is a key determinant for cingulate synaptic plasticity after nerve injury, which contributes to the maintenance of pain hypersensitivity and anxiety. Thereby, this study presents a strong basis for opening up a novel therapeutic target, PKG-I, in nociceptors for treatment of comorbidity of neuropathic pain and anxiety with least side effects.
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Shi C, Qiu S, Riester SM, Das V, Zhu B, Wallace AA, van Wijnen AJ, Mwale F, Iatridis JC, Sakai D, Votta-Velis G, Yuan W, Im HJ. Animal models for studying the etiology and treatment of low back pain. J Orthop Res 2018; 36:1305-1312. [PMID: 28921656 PMCID: PMC6287742 DOI: 10.1002/jor.23741] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 09/13/2017] [Indexed: 02/04/2023]
Abstract
Chronic low back pain is a major cause of disability and health care costs. Effective treatments are inadequate for many patients. Animal models are essential to further understanding of the pain mechanism and testing potential therapies. Currently, a number of preclinical models have been developed attempting to mimic aspects of clinical conditions that contribute to low back pain (LBP). This review focused on describing these animal models and the main behavioral tests for assessing pain in each model. Animal models of LBP can be divided into the following five categories: Discogenic LBP, radicular back pain, facet joint osteoarthritis back pain, muscle-induced LBP, and spontaneous occurring LBP models. These models are important not only for enhancing our knowledge of how LBP is generated, but also for the development of novel therapeutic regimens to treat LBP in patients. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1305-1312, 2018.
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Affiliation(s)
- Changgui Shi
- Department of Orthopedic Surgery, Changzheng Hospital,
Second Military Medical University of China, Shanghai, China
| | - Sujun Qiu
- Department of Orthopedic Surgery, Zhujiang Hospital,
Southern Medical University, Guangzhou, China
| | - Scott M. Riester
- Department of Orthopedic Surgery, Mayo Clinic, Rochester,
Minnesota
| | - Vaskar Das
- Department of Biochemistry, Rush University Medical Center,
Chicago, Illinois
| | - Bingqian Zhu
- Departments of Biobehavioral Health Science, University of
Illinois at Chicago (UIC), Chicago, Illinois
| | | | | | - Fackson Mwale
- Department of Surgery, McGill University and Orthopaedic
Research Laboratory, Lady Davis Institute for Medical Research, SMBD-Jewish General
Hospital, Montreal, Canada
| | - James C. Iatridis
- Leni & Peter May Department of Orthopaedics, Icahn
School of Medicine at Mount Sinai, New York, New York
| | - Daisuke Sakai
- Department of Orthopaedic Surgery, Tokai University School
of Medicine, Kanagawa, Japan
| | - Gina Votta-Velis
- Department of Anesthesiology, University of Illinois at
Chicago (UIC), Chicago, Illinois,,Jesse Brown Veterans Affairs Medical Center (JBVAMC) at
Chicago, Chicago, Illinois
| | - Wen Yuan
- Department of Orthopedic Surgery, Changzheng Hospital,
Second Military Medical University of China, Shanghai, China
| | - Hee-Jeong Im
- Jesse Brown Veterans Affairs Medical Center (JBVAMC) at
Chicago, Chicago, Illinois,,Department of Bioengineering, University of Illinois at
Chicago (UIC), Chicago, Illinois
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Yu Y, Huang X, Di Y, Qu L, Fan N. Effect of CXCL12/CXCR4 signaling on neuropathic pain after chronic compression of dorsal root ganglion. Sci Rep 2017; 7:5707. [PMID: 28720830 PMCID: PMC5515923 DOI: 10.1038/s41598-017-05954-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 06/07/2017] [Indexed: 01/16/2023] Open
Abstract
Neuropathic pain is a complex, chronic pain state that often accompanies tissue damage, inflammation or injury of the nervous system. However the underlying molecular mechanisms still remain unclear. Here, we showed that CXCL12 and CXCR4 were upregulated in the dorsal root ganglion (DRG) after chronic compression of DRG (CCD), and some CXCR4 immunopositive neurons were also immunopositive for the nociceptive neuronal markers IB4, TRPV1, CGRP, and substance P. The incidence and amplitude of CXCL12-induced Ca2+ response in primary sensory neurons from CCD mice was significantly increased compared to those from control animals. CXCL12 depolarized the resting membrane potential, decreased the rheobase, and increased the number of action potentials evoked by a depolarizing current at 2X rheobase in neurons from CCD mice. The mechanical and thermal hypernociception after CCD was attenuated by administration of a CXCR4 antagonist AMD3100. These findings suggest that CXCL12/CXCR4 signaling contributes to hypernociception after CCD, and targeting CXCL12/CXCR4 signaling pathway may alleviate neuropathic pain.
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Affiliation(s)
- Yang Yu
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China
| | - Xini Huang
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China
| | - Yuwei Di
- Department of Pathology and Laboratory Medicine, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080, China
| | - Lintao Qu
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University School of Medicine, 725N. Wolfe St., Baltimore, MD, 21205, USA
| | - Ni Fan
- The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), 36 Mingxin Road, Liwan District, Guangzhou, Guangdong Province, 510370, China.
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Liu DL, Wang X, Chu WG, Lu N, Han WJ, Du YK, Hu SJ, Bai ZT, Wu SX, Xie RG, Luo C. Chronic cervical radiculopathic pain is associated with increased excitability and hyperpolarization-activated current ( I h) in large-diameter dorsal root ganglion neurons. Mol Pain 2017; 13:1744806917707127. [PMID: 28587505 PMCID: PMC5466279 DOI: 10.1177/1744806917707127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cervical radiculopathic pain is a very common symptom that may occur with cervical
spondylosis. Mechanical allodynia is often associated with cervical radiculopathic pain
and is inadequately treated with current therapies. However, the precise mechanisms
underlying cervical radiculopathic pain-associated mechanical allodynia have remained
elusive. Compelling evidence from animal models suggests a role of large-diameter dorsal
root ganglion neurons and plasticity of spinal circuitry attached with Aβ fibers in
mediating neuropathic pain. Whether cervical radiculopathic pain condition induces plastic
changes of large-diameter dorsal root ganglion neurons and what mechanisms underlie these
changes are yet to be known. With combination of patch-clamp recording,
immunohistochemical staining, as well as behavioral surveys, we demonstrated that upon
chronic compression of C7/8 dorsal root ganglions, large-diameter cervical dorsal root
ganglion neurons exhibited frequent spontaneous firing together with hyperexcitability.
Quantitative analysis of hyperpolarization-activated cation current
(Ih) revealed that Ih was
greatly upregulated in large dorsal root ganglion neurons from cervical radiculopathic
pain rats. This increased Ih was supported by the enhanced
expression of hyperpolarization-activated, cyclic nucleotide-modulated channels subunit 3
in large dorsal root ganglion neurons. Blockade of Ih with
selective antagonist, ZD7288 was able to eliminate the mechanical allodynia associated
with cervical radiculopathic pain. This study sheds new light on the functional plasticity
of a specific subset of large-diameter dorsal root ganglion neurons and reveals a novel
mechanism that could underlie the mechanical allodynia associated with cervical
radiculopathy.
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Affiliation(s)
- Da-Lu Liu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,2 Department of Radiation Medicine, Faculty of Preventive Medicine, Fourth Military Medical University, Xi'an, China
| | - Xu Wang
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,3 Research Center for Resource Polypeptide Drugs and College of Life Sciences, Yanan University, Yanan, China
| | - Wen-Guang Chu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Na Lu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China.,4 ART Center, Northwest Women's and Children's Hospital, Xi'an, China
| | - Wen-Juan Han
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Yi-Kang Du
- 5 The First Brigade, Fourth Military Medical University, Xi'an, China
| | - San-Jue Hu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Zhan-Tao Bai
- 3 Research Center for Resource Polypeptide Drugs and College of Life Sciences, Yanan University, Yanan, China
| | - Sheng-Xi Wu
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Rou-Gang Xie
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
| | - Ceng Luo
- 1 Department of Neurobiology and Collaborative Innovation Center for Brain Science, Fourth Military Medical University, Xi'an, China
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A Novel Nitronyl Nitroxide with Salicylic Acid Framework Attenuates Pain Hypersensitivity and Ectopic Neuronal Discharges in Radicular Low Back Pain. Neural Plast 2015; 2015:752782. [PMID: 26609438 PMCID: PMC4644553 DOI: 10.1155/2015/752782] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/31/2015] [Accepted: 04/07/2015] [Indexed: 01/04/2023] Open
Abstract
Evidence has accumulated that reactive oxygen species and inflammation play crucial roles in the development of chronic pain, including radicular low back pain. Nonsteroid anti-inflammatory drugs (NSAIDs), for example, salicylic acid, aspirin, provided analgesic effects in various types of pain. However, long-term use of these drugs causes unwanted side effects, which limits their implication. Stable nitronyl (NIT) nitroxide radicals have been extensively studied as a unique and interesting class of new antioxidants for protection against oxidative damage. The present study synthesized a novel NIT nitroxide radical with salicylic acid framework (SANR) to provide synergistic effect of both antioxidation and antiinflammation. We demonstrated for the first time that both acute and repeated SANR treatment exerted dramatic analgesic effect in radicular low back pain mimicked by chronic compression of dorsal root ganglion in rats. This analgesic potency was more potent than that produced by classical NSAIDs aspirin and traditional nitroxide radical Tempol alone. Furthermore, SANR-induced behavioral analgesia is found to be mediated, at least in partial, by a reduction of ectopic spontaneous discharges in injured DRG neurons. Therefore, the synthesized NIT nitroxide radical coupling with salicylic acid framework may represent a novel potential therapeutic candidate for treatment of chronic pain, including radicular low back pain.
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Wang T, Hurwitz O, Shimada SG, Qu L, Fu K, Zhang P, Ma C, LaMotte RH. Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice. PLoS One 2015; 10:e0137512. [PMID: 26356638 PMCID: PMC4565551 DOI: 10.1371/journal.pone.0137512] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 08/18/2015] [Indexed: 11/29/2022] Open
Abstract
Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli.
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Affiliation(s)
- Tao Wang
- Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Neuroscience Center, Department of Anatomy, Histology and Embryology, Beijing, China
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Olivia Hurwitz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Steven G. Shimada
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Lintao Qu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University, Baltimore, Maryland
| | - Kai Fu
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Pu Zhang
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Chao Ma
- Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Neuroscience Center, Department of Anatomy, Histology and Embryology, Beijing, China
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Robert H. LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Stokes JA, Cheung J, Eddinger K, Corr M, Yaksh TL. Toll-like receptor signaling adapter proteins govern spread of neuropathic pain and recovery following nerve injury in male mice. J Neuroinflammation 2013; 10:148. [PMID: 24321498 PMCID: PMC3896749 DOI: 10.1186/1742-2094-10-148] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 11/18/2013] [Indexed: 02/06/2023] Open
Abstract
Background Spinal Toll-like receptors (TLRs) and signaling intermediaries have been implicated in persistent pain states. We examined the roles of two major TLR signaling pathways and selected TLRs in a mononeuropathic allodynia. Methods L5 spinal nerve ligation (SNL) was performed in wild type (WT, C57BL/6) male and female mice and in male Tlr2-/-Tlr3-/-, Tlr4-/-, Tlr5-/-, Myd88-/-, Triflps2, Myd88/Triflps2, Tnf-/-, and Ifnar1-/- mice. We also examined L5 ligation in Tlr4-/- female mice. We examined tactile allodynia using von Frey hairs. Iba-1 (microglia) and GFAP (astrocytes) were assessed in spinal cords by immunostaining. Tactile thresholds were analyzed by 1- and 2-way ANOVA and the Bonferroni post hoc test was used. Results In WT male and female mice, SNL lesions resulted in a persistent and robust ipsilateral, tactile allodynia. In males with TLR2, 3, 4, or 5 deficiencies, tactile allodynia was significantly, but incompletely, reversed (approximately 50%) as compared to WT. This effect was not seen in female Tlr4-/- mice. Increases in ipsilateral lumbar Iba-1 and GFAP were seen in mutant and WT mice. Mice deficient in MyD88, or MyD88 and TRIF, showed an approximately 50% reduction in withdrawal thresholds and reduced ipsilateral Iba-1. In contrast, TRIF and interferon receptor null mice developed a profound ipsilateral and contralateral tactile allodynia. In lumbar sections of the spinal cords, we observed a greater increase in Iba-1 immunoreactivity in the TRIF-signaling deficient mice as compared to WT, but no significant increase in GFAP. Removing MyD88 abrogated the contralateral allodynia in the TRIF signaling-deficient mice. Conversely, IFNβ, released downstream to TRIF signaling, administered intrathecally, temporarily reversed the tactile allodynia. Conclusions These observations suggest a critical role for the MyD88 pathway in initiating neuropathic pain, but a distinct role for the TRIF pathway and interferon in regulating neuropathic pain phenotypes in male mice.
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Affiliation(s)
| | | | | | | | - Tony L Yaksh
- Department of Pharmacology, University of California, 9500 Gilman Dr, MC 0636, La Jolla, San Diego, CA 92093-0636, USA.
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Pitcher GM, Ritchie J, Henry JL. Peripheral neuropathy induces cutaneous hypersensitivity in chronically spinalized rats. PAIN MEDICINE 2013; 14:1057-71. [PMID: 23855791 DOI: 10.1111/pme.12123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND/OBJECTIVES The present study was aimed at the issue of whether peripheral nerve injury-induced chronic pain is maintained by supraspinal structures governing descending facilitation to the spinal dorsal horn, or whether altered peripheral nociceptive mechanisms sustain central hyperexcitability and, in turn, neuropathic pain. We examined this question by determining the contribution of peripheral/spinal mechanisms, isolated from supraspinal influence(s), in cutaneous hypersensitivity in an animal model of peripheral neuropathy. METHODS Adult rats were spinalized at T8-T9; 8 days later, peripheral neuropathy was induced by implanting a 2-mm polyethylene cuff around the left sciatic nerve. Hind paw withdrawal responses to mechanical or thermal plantar stimulation were evaluated using von Frey filaments or a heat lamp, respectively. RESULTS Spinalized rats without cuff implantation exhibited a moderate decrease in mechanical withdrawal threshold on ~day 10 (P < 0.05) and in thermal withdrawal threshold on ~day 18 (P < 0.05). However, cuff-implanted spinalized rats developed a more rapid and significant decrease in mechanical (~day 4; P < 0.001) and thermal (~day 10; P < 0.05) withdrawal thresholds that remained significantly decreased through the duration of the study. CONCLUSIONS Our findings demonstrate an aberrant peripheral/spinal mechanism that induces and maintains thermal and to a greater degree tactile cutaneous hypersensitivity in the cuff model of neuropathic pain, and raise the prospect that altered peripheral/spinal nociceptive mechanisms in humans with peripheral neuropathy may have a pathologically relevant role in both inducing and sustaining neuropathic pain.
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Affiliation(s)
- Graham M Pitcher
- Departments of Physiology and Psychiatry, McGill University, Montreal, Quebec, Canada.
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Strong JA, Xie W, Bataille FJ, Zhang JM. Preclinical studies of low back pain. Mol Pain 2013; 9:17. [PMID: 23537369 PMCID: PMC3617092 DOI: 10.1186/1744-8069-9-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/18/2013] [Indexed: 12/12/2022] Open
Abstract
Chronic low back pain is a major cause of disability and health care costs. Current treatments are inadequate for many patients. A number of preclinical models have been developed that attempt to mimic aspects of clinical conditions that contribute to low back pain. These involve application of nucleus pulposus material near the lumbar dorsal root ganglia (DRG), chronic compression of the DRG, or localized inflammation of the DRG. These models, which are primarily implemented in rats, have many common features including behavioral hypersensitivity of the hindpaw, enhanced excitability and spontaneous activity of sensory neurons, and locally elevated levels of inflammatory mediators including cytokines. Clinically, epidural injection of steroids (glucocorticoids) is commonly used when more conservative treatments fail, but clinical trials evaluating these treatments have yielded mixed results. There are relatively few preclinical studies of steroid effects in low back pain models. One preclinical study suggests that the mineralocorticoid receptor, also present in the DRG, may have pro-inflammatory effects that oppose the activation of the glucocorticoid receptor. Although the glucocorticoid receptor is the target of anti-inflammatory steroids, many clinically used steroids activate both receptors. This could be one explanation for the limited effects of epidural steroids in some patients. Additional preclinical research is needed to address other possible reasons for limited efficacy of steroids, such as central sensitization or presence of an ongoing inflammatory stimulus in some forms of low back pain.
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Affiliation(s)
- Judith A Strong
- Pain Research Center, Department of Anesthesiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0531, USA
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