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Drinovac Vlah V, Bach-Rojecky L. Mirror-Image Pain Update: Complex Interactions Between Central and Peripheral Mechanisms. Mol Neurobiol 2024:10.1007/s12035-024-04102-x. [PMID: 38602655 DOI: 10.1007/s12035-024-04102-x] [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: 10/03/2022] [Accepted: 03/06/2024] [Indexed: 04/12/2024]
Abstract
The appearance of contralateral effects after unilateral injury has been shown in various experimental pain models, as well as in clinics. They consist of a diversity of phenomena in contralateral peripheral nerves, sensory ganglia, or spinal cord: from structural changes and altered gene or protein expression to functional consequences such as the development of mirror-image pain (MP). Although MP is a well-documented phenomenon, the exact molecular mechanism underlying the induction and maintenance of mirror-like spread of pain is still an unresolved challenge. MP has generally been explained by central sensitization mechanisms leading to facilitation of pain impulse transfer through neural connections between the two sides of the central nervous system. On the contrary, the peripheral nervous system (PNS) was usually regarded unlikely to evoke such a symmetrical phenomenon. However, recent findings provided evidence that events in the PNS could play a significant role in MP induction. This manuscript provides an updated and comprehensive synthesis of the MP phenomenon and summarizes the available data on the mechanisms. A more detailed focus is placed on reported evidence for peripheral mechanisms behind the MP phenomenon, which were not reviewed up to now.
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Affiliation(s)
- Višnja Drinovac Vlah
- Department of Pharmacology, University of Zagreb Faculty of Pharmacy and Biochemistry, Domagojeva 2, 10000, Zagreb, Croatia
| | - Lidija Bach-Rojecky
- Department of Pharmacology, University of Zagreb Faculty of Pharmacy and Biochemistry, Domagojeva 2, 10000, Zagreb, Croatia.
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2
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Li W, Gong Y, Liu J, Guo Y, Tang H, Qin S, Zhao Y, Wang S, Xu Z, Chen B. Peripheral and Central Pathological Mechanisms of Chronic Low Back Pain: A Narrative Review. J Pain Res 2021; 14:1483-1494. [PMID: 34079363 PMCID: PMC8166276 DOI: 10.2147/jpr.s306280] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/01/2021] [Indexed: 12/31/2022] Open
Abstract
Chronic low back pain (CLBP), lasting >3 months, is the end result of multiple pathogenic factors. Unfortunately, little is known about CLBP pathogenesis, which limits its advancements in clinical therapy and disease management. This paper summarizes the known pathological axes of CLBP, involving both peripheral and central systems. In particular, this paper details injurious nerve stimulation, inflammation-induced peripheral pathway, and central sensitization. Lumbar components, such as intervertebral disc (IVD), facet joints, muscles, fascia, ligaments, and joint capsules, contain pain receptors called nociceptors. Degeneration of the aforementioned lumbar components activates inflammatory pathways, which can directly damage nerves, lower nociceptor threshold to fire action potentials (AP), and cause pain. Additionally, damaged lumbar IVDs and endplates can also lead to the pathologic invasion of nerve growth and innervation, followed by the compression of herniated IVDs on nerve roots, thereby causing traumatic neuropathic pain. The central mechanism of CLBP involves alteration of the sensory processing of the brain and malfunction of the descending pain modulatory system, which facilitates pain amplification in the center nervous system (CNS). Lastly, abnormalities in the brain biochemical metabolism, activation of glial cells, and subsequent inflammation also play important roles in CLBP development. Taken together, inflammation plays an important role in both peripheral and central sensitization of CLBP. Due to the heterogeneity of CLBP, its pathological mechanism remains complex and difficult to understand. Therefore, it is a worthy field for future research into the subcomponents of CLBP pathogenesis, in order to distinguish the specific form of the disease, identify its origins, and develop corresponding highly effective comprehensive therapy against CLBP.
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Affiliation(s)
- Wei Li
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Yinan Gong
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Jingyi Liu
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Yongming Guo
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,School of Acupuncture & Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, 300381, People's Republic of China
| | - Huiling Tang
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Siru Qin
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Yadan Zhao
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Songtao Wang
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Zhifang Xu
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,School of Acupuncture & Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, 300381, People's Republic of China
| | - Bo Chen
- Research Center of Experimental Acupuncture Science, Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,School of Acupuncture & Moxibustion and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, 300381, People's Republic of China
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Nicol AL, Adams MCB, Gordon DB, Mirza S, Dickerson D, Mackey S, Edwards D, Hurley RW. AAAPT Diagnostic Criteria for Acute Low Back Pain with and Without Lower Extremity Pain. PAIN MEDICINE (MALDEN, MASS.) 2020; 21:2661-2675. [PMID: 32914195 PMCID: PMC8453619 DOI: 10.1093/pm/pnaa239] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Low back pain is one of the most common reasons for which people visit their doctor. Between 12% and 15% of the US population seek care for spine pain each year, with associated costs exceeding $200 billion. Up to 80% of adults will experience acute low back pain at some point in their lives. This staggering prevalence supports the need for increased research to support tailored clinical care of low back pain. This work proposes a multidimensional conceptual taxonomy. METHODS A multidisciplinary task force of the ACTTION-APS-AAPM Pain Taxonomy (AAAPT) with clinical and research expertise performed a focused review and analysis, applying the AAAPT five-dimensional framework to acute low back pain. RESULTS Application of the AAAPT framework yielded the following: 1) Core Criteria: location, timing, and severity of acute low back pain were defined; 2) Common Features: character and expected trajectories were established in relevant subgroups, and common pain assessment tools were identified; 3) Modulating Factors: biological, psychological, and social factors that modulate interindividual variability were delineated; 4) Impact/Functional Consequences: domains of impact were outlined and defined; 5) Neurobiological Mechanisms: putative mechanisms were specified including nerve injury, inflammation, peripheral and central sensitization, and affective and social processing of acute low back pain. CONCLUSIONS The goal of applying the AAAPT taxonomy to acute low back pain is to improve its assessment through a defined evidence and consensus-driven structure. The criteria proposed will enable more rigorous meta-analyses and promote more generalizable studies of interindividual variation in acute low back pain and its potential underlying mechanisms.
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Affiliation(s)
- Andrea L Nicol
- Department of Anesthesiology, University of Kansas School of Medicine, Kansas City, Kansas
| | - Meredith C B Adams
- Department of Anesthesiology, Wake Forest University School of Medicine, Winston Salem, North Carolina
| | - Debra B Gordon
- Department of Biobehavioral Nursing and Health Systems, University of Washington, Seattle, Washington
| | - Sohail Mirza
- Department of Orthopedic Surgery, Geisel School of Medicine at Dartmouth University, Hanover, New Hampshire
| | - David Dickerson
- Department of Anesthesiology, NorthShore University Health System, Evanston, Illinois
| | - Sean Mackey
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Stanford, California
| | - David Edwards
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Robert W Hurley
- Department of Anesthesiology, Wake Forest University School of Medicine, Winston Salem, North Carolina
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston Salm, North Carolina, USA
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The AMPK pathway triggers autophagy during CSF1-induced microglial activation and may be implicated in inducing neuropathic pain. J Neuroimmunol 2020; 345:577261. [PMID: 32570135 DOI: 10.1016/j.jneuroim.2020.577261] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 05/03/2020] [Accepted: 05/04/2020] [Indexed: 02/06/2023]
Abstract
The development and maintenance of neuropathic pain is now given far more attention in the clinic work. Increasing evidence has shown that colony-stimulating factor 1 (CSF1) is involved in microglial activation and may further induce pain. Here, we observed the signaling events that link the CSF1-induced microglial activated and consequences for pain processing. For the in vitro study, flow cytometry showed the microglial activity was markedly increased after CSF1 stimulation. Western blot showed the increased expression of p-PRKAA1/PRKAA1, p-AMPK/AMPK, p-ULK1/ULK1, p-S6k/S6k and LC3-II/LC3-I. QRT-PCR showed the IL-1, TNF-α and BDNF were simultaneously upregulated in the activated microglia cells, whereas the specific AMPK inhibitor compound C exhibited reverse effects in microglia. Using immunofluorescence staining and electron microscopy, we found CSF1 decreased microglial p62 expression and induced the number of autophagosomes, whereas compound C significantly exhibited the reverse effects. For the in vivo study, compared with the control and AMPK-siRNA transfection, the mice under CSF1 intrathecal injection increased CSF1 receptor and LC3 expressed in the activated spinal microglia. More importantly, qRT-PCR showed CSF1 intrathecal injection substantially upregulated BDNF and c-Fos mRNA expression as well as the ensuing neuropathic pain. Our findings demonstrated that CSF1 induced a significant upregulation of microglial activation via the AMPK signaling pathway and resulted in an increasing microglial autophagic level. An increasing CSF1 level in the central nervous system can mimic and cause pain syndromes by up-regulation of AMPK-depended autophagy, thus offering a new target for the therapy of neuropathic pain.
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Markman JD, Czerniecka-Foxx K, Khalsa PS, Hayek SM, Asher AL, Loeser JD, Chou R. AAPT Diagnostic Criteria for Chronic Low Back Pain. THE JOURNAL OF PAIN 2020; 21:1138-1148. [PMID: 32036046 DOI: 10.1016/j.jpain.2020.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 12/15/2022]
Abstract
Chronic low back pain (CLBP) conditions are highly prevalent and constitute the leading cause of disability worldwide. The Analgesic, Anesthetic, and Addiction Clinical Trial Translations Innovations Opportunities and Networks (ACTTION) public-private partnership with the US Food and Drug Administration and the American Pain Society (APS), have combined to create the ACTTION-APS Pain Taxonomy (AAPT). The AAPT initiative convened a working group to develop diagnostic criteria for CLBP. The working group identified 3 distinct low back pain conditions which result in a vast public health burden across the lifespan. This article focuses on: 1) the axial predominant syndrome of chronic musculoskeletal low back pain, 2) the lateralized, distally-radiating syndrome of chronic lumbosacral radicular pain 3) and neurogenic claudication associated with lumbar spinal stenosis. This classification of CLBP is organized according to the AAPT multidimensional framework, specifically 1) core diagnostic criteria; 2) common features; 3) common medical and psychiatric comorbidities; 4) neurobiological, psychosocial, and functional consequences; and 5) putative neurobiological and psychosocial mechanisms, risk factors, and protective factors. PERSPECTIVE: An evidence-based classification of CLBP conditions was constructed for the AAPT initiative. This multidimensional diagnostic framework includes: 1) core diagnostic criteria; 2) common features; 3) medical and psychiatric comorbidities; 4) neurobiological, psychosocial, and functional consequences; and 5) putative neurobiological and psychosocial mechanisms, risk factors, and protective factors.
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Affiliation(s)
- John D Markman
- Translational Pain Research Program, Department of Neurosurgery, University of Rochester, Rochester, New York.
| | | | - Partap S Khalsa
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, Maryland
| | - Salim Michel Hayek
- Division of Pain Medicine, Department of Anesthesiology, Case Western Reserve University, University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Anthony L Asher
- Department of Neurological Surgery, Carolina Neurosurgery and Spine Associates and Neuroscience Institute, Atrium Health, Charlotte, North Carolina
| | - John D Loeser
- Department of Neurological Surgery, University of Washington, Seattle, Washington
| | - Roger Chou
- Department of Medicine, Oregon Health & Science University, Portland, Oregon
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Lin HT, Chiu CC, Liu CC, Chen YW, Wang JJ, Hung CH. Ultrasound therapy reduces persistent post-thoracotomy tactile allodynia and spinal substance P expression in rats. Reg Anesth Pain Med 2019; 44:604-608. [PMID: 30902913 DOI: 10.1136/rapm-2018-100113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 01/19/2019] [Accepted: 02/13/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Therapeutic ultrasound (TU) alleviates nerve injury-associated pain, while the molecular mechanisms are less clear. This is an investigator-initiated experimental study to evaluate the mechanisms and effects of ultrasound on prolonged post-thoracotomy pain in a rodent model. METHODS The rats were randomly separated into four groups (n=8 per group): sham-operation (sham; group 1), thoracotomy and rib retraction (TRR; group 2), and TRR procedure followed by TU (TRR+TU-3; group 3) or TU with the ultrasound power turned off (TRR+TU-0; group 4). TU was delivered daily, beginning on postoperative day 11 (POD 11) for the next 2 weeks. Mechanical sensitivity, subcutaneous tissue temperature, and spinal substance P and interleukin-1 beta (IL-1β) were evaluated on PODs 11 and 23. RESULTS Group 3, which received ultrasound treatment (3 MHz; 1.0 W/cm2) for 5 min each day, demonstrated higher mechanical withdrawal thresholds when compared with the group without ultrasound intervention (group 2) or sham ultrasound (group 4). Ultrasound treatment also inhibited the upregulation of spinal substance P and IL-1β measured from spinal cord dorsal horns extract and increased subcutaneous temperature. CONCLUSIONS The results of this study suggest an increase in mechanical withdrawal thresholds and subcutaneous temperature, as well as a downregulation of spinal substance P and IL-1β, in the group which received ultrasound treatment. The regulation of spinal substance P and IL-1β may mediate potential effects of this non-invasive treatment.
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Affiliation(s)
- Heng-Teng Lin
- Department of Physical Medicine and Rehabilitation, Madou Sin-Lau Hospital, Tainan, Taiwan
- Department of Nursing, Chung Hwa University of Medical Technology, Tainan, Taiwan
| | - Chong-Chi Chiu
- Department of General Surgery, Chi Mei Medical Center, Tainan and Liouying, Taiwan
- Department of Electrical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Chen-Chih Liu
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Wen Chen
- Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan
- Department of Physical Therapy, College of Health Care, China Medical University, Taichung, Taiwan
| | - Jhi-Joung Wang
- Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan
- Allied AI Biomed Center, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Ching-Hsia Hung
- Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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IKK/NF-κB-dependent satellite glia activation induces spinal cord microglia activation and neuropathic pain after nerve injury. Pain 2018; 158:1666-1677. [PMID: 28722693 DOI: 10.1097/j.pain.0000000000000959] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Increasing evidence indicates that both microglia and satellite glial cell (SGC) activation play causal roles in neuropathic pain development after peripheral nerve injury; however, the activation mechanisms and their contribution to neuropathic pain remain elusive. To address this issue, we generated Ikkβ conditional knockout mice (Cnp-Cre/Ikkβ; cIkkβ) in which IKK/NF-κB-dependent proinflammatory SGC activation was abrogated. In these mice, nerve injury-induced spinal cord microglia activation and pain hypersensitivity were significantly attenuated compared to those in control mice. In addition, nerve injury-induced proinflammatory gene expression and macrophage infiltration into the dorsal root ganglion (DRG) were severely compromised. However, macrophages recruited into the DRG had minimal effects on spinal cord microglia activation, suggesting a causal effect for SGC activation on spinal cord microglia activation. In an effort to elucidate the molecular mechanisms, we measured Csf1 expression in the DRG, which is implicated in spinal cord microglia activation after nerve injury. In cIkkβ mice, nerve injury-induced Csf1 upregulation was ameliorated indicating that IKK/NF-κΒ-dependent SGC activation induced Csf1 expression in sensory neurons. Taken together, our data suggest that nerve injury-induced SGC activation triggers Csf1 induction in sensory neurons, spinal cord microglia activation, and subsequent central pain sensitization.
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8
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Stretching of roots contributes to the pathophysiology of radiculopathies. Joint Bone Spine 2018; 85:41-45. [DOI: 10.1016/j.jbspin.2017.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/05/2017] [Indexed: 12/26/2022]
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Holló K, Ducza L, Hegyi Z, Dócs K, Hegedűs K, Bakk E, Papp I, Kis G, Mészár Z, Bardóczi Z, Antal M. Interleukin-1 receptor type 1 is overexpressed in neurons but not in glial cells within the rat superficial spinal dorsal horn in complete Freund adjuvant-induced inflammatory pain. J Neuroinflammation 2017. [PMID: 28645297 PMCID: PMC5482961 DOI: 10.1186/s12974-017-0902-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Background All known biological functions of the pro-inflammatory cytokine interleukin-1β (IL-1β) are mediated by type 1 interleukin receptor (IL-1R1). IL-1β–IL-1R1 signaling modulates various neuronal functions including spinal pain processing. Although the role of IL-1β in pain processing is generally accepted, there is a discussion in the literature whether IL-1β exerts its effect on spinal pain processing by activating neuronal or glial IL-1R1. To contribute to this debate, here we investigated the expression and cellular distribution of IL-1R1 in the superficial spinal dorsal horn in control animals and also in inflammatory pain. Methods Experiments were performed on rats and wild type as well as IL-1R1-deficient mice. Inflammatory pain was evoked by unilateral intraplantar injection of complete Freund adjuvant (CFA). The nociceptive responsiveness of control and CFA-treated animals were tested daily for withdrawal responses to mechanical and thermal stimuli before and after CFA injection. Changes in the expression of 48 selected genes/mRNAs and in the quantity of IL-1R1 protein during the first 3 days after CFA injection were measured with the TaqMan low-density array method and Western blot analysis, respectively. The cellular localization of IL-1R1 protein was investigated with single and double staining immunocytochemical methods. Results We found a six times and two times increase in IL-1R1 mRNA and protein levels, respectively, in the dorsal horn of CFA-injected animals 3 days after CFA injection, at the time of the summit of mechanical and thermal allodynia. Studying the cellular distribution of IL-1R1, we found an abundant expression of IL-1R1 on the somatodendritic compartment of neurons and an enrichment of the receptor in the postsynaptic membranes of some excitatory synapses. In contrast to the robust neuronal localization, we observed only a moderate expression of IL-1R1 on astrocytes and a negligible one on microglial cells. CFA injection into the hind paw caused a remarkable increase in the expression of IL-1R1 in neurons, but did not alter the glial expression of the receptor. Conclusion The results suggest that IL-1β exerts its effect on spinal pain processing primarily through neuronal IL-1R1, but it can also interact in some extent with IL-1R1 expressed by astrocytes.
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Affiliation(s)
- Krisztina Holló
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - László Ducza
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zoltán Hegyi
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Klaudia Dócs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Erzsébet Bakk
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Ildikó Papp
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary.,Department of Anatomy, Histology and Embryology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zoltán Mészár
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary
| | - Zsuzsanna Bardóczi
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, 4012, Debrecen, Hungary. .,MTA-DE Neuroscience Research Group, Nagyerdei krt. 98, 4012, Debrecen, Hungary.
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Huang PC, Tsai KL, Chen YW, Lin HT, Hung CH. Exercise Combined With Ultrasound Attenuates Neuropathic Pain in Rats Associated With Downregulation of IL-6 and TNF-α, but With Upregulation of IL-10. Anesth Analg 2017; 124:2038-2044. [DOI: 10.1213/ane.0000000000001600] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Hüllemann P, von der Brelie C, Manthey G, Düsterhöft J, Helmers A, Synowitz M, Baron R. Reduced laser-evoked potential habituation detects abnormal central pain processing in painful radiculopathy patients. Eur J Pain 2017; 21:918-926. [DOI: 10.1002/ejp.994] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2016] [Indexed: 11/06/2022]
Affiliation(s)
- P. Hüllemann
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - C. von der Brelie
- Department of Neurosurgery; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - G. Manthey
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - J. Düsterhöft
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - A.K. Helmers
- Department of Neurosurgery; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - M. Synowitz
- Department of Neurosurgery; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
| | - R. Baron
- Division of Neurological Pain Research and Therapy; Department of Neurology; University Hospital Schleswig-Holstein Campus Kiel; Kiel Germany
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Therapeutic Ultrasound and Treadmill Training Suppress Peripheral Nerve Injury-Induced Pain in Rats. Phys Ther 2016; 96:1545-1553. [PMID: 27126126 DOI: 10.2522/ptj.20140379] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 04/24/2016] [Indexed: 02/09/2023]
Abstract
BACKGROUND Although evidence suggests that therapeutic ultrasound (TU) in combination with treadmill training (TT) suppresses nerve injury-associated pain, the molecular mechanisms for this action are not clear. OBJECTIVE The purpose of this research was to study the possible beneficial effects of TU and TT, alone and in combination, on 2 clinical indicators of neuropathic pain and correlate these findings with changes in inflammatory mediators within the spinal cord. Our experimental model used the well-known chronic constriction injury (CCI) of the rat sciatic nerve. DESIGN This was an experimental study. METHODS Each group contained 10 rats. Group 1 underwent only the CCI procedure. Group 2 underwent a sham operation where the sciatic nerve was exposed but not ligated. Group 3 had the sham operation followed by both TT and TU. Groups 4, 5, and 6 underwent the CCI procedure followed by TT alone, TU alone, and both the TT and TU interventions, respectively. Heat and mechanical sensitivity, interleukin-6 (IL-6), interleukin-10 (IL-10), and ionized calcium binding adaptor molecule 1 (Iba1) were evaluated. RESULTS Compared with group 1 animals, TT or TU, or both, produced smaller decreases in mechanical withdrawal threshold and heat withdrawal latencies. The combination of TT and TU was more effective than either treatment alone. In addition, rats that received these treatments did not express the upregulation of IL-6 and Iba1 in their spinal cords on postoperative days 14 and 28, as was found in the group 1 animals. LIMITATIONS These experimental findings may not be generalizable to humans. CONCLUSIONS The combination of TU and TT reduces neuropathic pain more than either modality alone. This beneficial effect appears related to downregulation of proinflammatory IL-6 and Iba1, while upregulating the anti-inflammatory IL-10.
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Abstract
In the somatosensory system, P2X receptors are expressed on both peripheral and central terminals of primary afferent neurons. Those expressed on peripheral terminals are activated in response to both nociceptive and innocuous stimuli, whereas those at central terminals (“central terminal P2X receptors”) play an important role in modulating sensory transmission to the spinal cord dorsal horn. The author reviews recent studies on the central terminal P2X receptors. It is proposed that central terminal P2X receptors, once activated, may be involved in both central sensitization and initiation of pain. Thus, these receptors may repesent a promising target for therapeutic management of pathological pain.
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Affiliation(s)
- Jianguo G Gu
- Department of Oral Surgery, Division of Neuroscience, McKnight Brain Institute and College of Dentistry, University of Florida, Gainesville 32610, USA.
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14
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Variations in potassium channel genes are associated with distinct trajectories of persistent breast pain after breast cancer surgery. Pain 2015; 156:371-380. [PMID: 25599232 DOI: 10.1097/01.j.pain.0000460319.87643.11] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Persistent pain after breast cancer surgery is a common clinical problem. Given the role of potassium channels in modulating neuronal excitability, coupled with recently published genetic associations with preoperative breast pain, we hypothesized that variations in potassium channel genes will be associated with persistent postsurgical breast pain. In this study, associations between 10 potassium channel genes and persistent breast pain were evaluated. Using growth mixture modeling (GMM), 4 distinct latent classes of patients, who were assessed before and monthly for 6 months after breast cancer surgery, were identified previously (ie, No Pain, Mild Pain, Moderate Pain, Severe Pain). Genotyping was done using a custom array. Using logistic regression analyses, significant differences in a number of genotype or haplotype frequencies were found between: Mild Pain vs No Pain and Severe Pain vs No Pain classes. Seven single-nucleotide polymorphisms (SNPs) across 5 genes (ie, potassium voltage-gated channel, subfamily A, member 1 [KCNA1], potassium voltage-gated channel, subfamily D, member 2 [KCND2], potassium inwardly rectifying channel, subfamily J, members 3 and 6 (KCNJ3 and KCNJ6), potassium channel, subfamily K, member 9 [KCNK9]) were associated with membership in the Mild Pain class. In addition, 3 SNPs and 1 haplotype across 4 genes (ie, KCND2, KCNJ3, KCNJ6, KCNK9) were associated with membership in the Severe Pain class. These findings suggest that variations in potassium channel genes are associated with both mild and severe persistent breast pain after breast cancer surgery. Although findings from this study warrant replication, they provide intriguing preliminary information on potential therapeutic targets.
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Zeeman ME, Kartha S, Jaumard NV, Baig HA, Stablow AM, Lee J, Guarino BB, Winkelstein BA. Whole-body Vibration at Thoracic Resonance Induces Sustained Pain and Widespread Cervical Neuroinflammation in the Rat. Clin Orthop Relat Res 2015; 473:2936-47. [PMID: 25917423 PMCID: PMC4523525 DOI: 10.1007/s11999-015-4315-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Whole-body vibration (WBV) is associated with back and neck pain in military personnel and civilians. However, the role of vibration frequency and the physiological mechanisms involved in pain symptoms are unknown. QUESTIONS/PURPOSES This study asked the following questions: (1) What is the resonance frequency of the rat spine for WBV along the spinal axis, and how does frequency of WBV alter the extent of spinal compression/extension? (2) Does a single WBV exposure at resonance induce pain that is sustained? (3) Does WBV at resonance alter the protein kinase C epsilon (PKCε) response in the dorsal root ganglia (DRG)? (4) Does WBV at resonance alter expression of calcitonin gene-related peptide (CGRP) in the spinal dorsal horn? (5) Does WBV at resonance alter the spinal neuroimmune responses that regulate pain? METHODS Resonance of the rat (410 ± 34 g, n = 9) was measured by imposing WBV at frequencies from 3 to 15 Hz. Separate groups (317 ± 20 g, n = 10/treatment) underwent WBV at resonance (8 Hz) or at a nonresonant frequency (15 Hz). Behavioral sensitivity was assessed throughout to measure pain, and PKCε in the DRG was quantified as well as spinal CGRP, glial activation, and cytokine levels at Day 14. RESULTS Accelerometer-based thoracic transmissibility peaks at 8 Hz (1.86 ± 0.19) and 9 Hz (1.95 ± 0.19, mean difference [MD] 0.290 ± 0.266, p < 0.03), whereas the video-based thoracic transmissibility peaks at 8 Hz (1.90 ± 0.27), 9 Hz (2.07 ± 0.20), and 10 Hz (1.80 ± 0.25, MD 0.359 ± 0.284, p < 0.01). WBV at 8 Hz produces more cervical extension (0.745 ± 0.582 mm, MD 0.242 ± 0.214, p < 0.03) and compression (0.870 ± 0.676 mm, MD 0.326 ± 0.261, p < 0.02) than 15 Hz (extension, 0.503 ± 0.279 mm; compression, 0.544 ± 0.400 mm). Pain is longer lasting (through Day 14) and more robust (p < 0.01) after WBV at the resonant frequency (8 Hz) compared with 15 Hz WBV. PKCε in the nociceptors of the DRG increases according to the severity of WBV with greatest increases after 8 Hz WBV (p < 0.03). However, spinal CGRP, cytokines, and glial activation are only evident after painful WBV at resonance. CONCLUSIONS WBV at resonance produces long-lasting pain and widespread activation of a host of nociceptive and neuroimmune responses as compared with WBV at a nonresonance condition. Based on this work, future investigations into the temporal and regional neuroimmune response to resonant WBV in both genders would be useful. CLINICAL RELEVANCE Although WBV is a major issue affecting the military population, there is little insight about its mechanisms of injury and pain. The neuroimmune responses produced by WBV are similar to other pain states, suggesting that pain from WBV may be mediated by similar mechanisms as other neuropathic pain conditions. This mechanistic insight suggests WBV-induced injury and pain may be tempered by antiinflammatory intervention.
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Affiliation(s)
- Martha E. Zeeman
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Sonia Kartha
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Nicolas V. Jaumard
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Hassam A. Baig
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Alec M. Stablow
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Jasmine Lee
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Benjamin B. Guarino
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
| | - Beth A. Winkelstein
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S 33rd Street, Philadelphia, PA 19104-6321 USA
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Time-specific microRNA changes during spinal motoneuron degeneration in adult rats following unilateral brachial plexus root avulsion: ipsilateral vs. contralateral changes. BMC Neurosci 2014; 15:92. [PMID: 25055855 PMCID: PMC4121484 DOI: 10.1186/1471-2202-15-92] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 07/16/2014] [Indexed: 01/08/2023] Open
Abstract
Background Spinal root avulsion induces multiple pathophysiological events consisting of altered levels of specific genes and proteins related to inflammation, apoptosis, and oxidative stress, which collectively result in the death of the affected motoneurons. Recent studies have demonstrated that the gene changes involved in spinal cord injury can be regulated by microRNAs, which are a class of short non-coding RNA molecules that repress target mRNAs post-transcriptionally. With consideration for the time course of the avulsion-induced gene expression patterns within dying motoneurons, we employed microarray analysis to determine whether and how microRNAs are involved in the changes of gene expression induced by pathophysiological events in spinal cord motoneurons. Results The expression of a total of 3,361 miRNAs in the spinal cord of adult rats was identified. Unilateral root-avulsion resulted in significant alterations in miRNA expression. In the ipsilateral half compared to the contralateral half of the spinal cord, on the 3rd day after the injury, 55 miRNAs were upregulated, and 24 were downregulated, and on the 14th day after the injury, 36 miRNAs were upregulated, and 23 were downregulated. The upregulation of miR-146b-5p and miR-31a-3p and the downregulation of miR-324-3p and miR-484 were observed. Eleven of the miRNAs, including miR-21-5p, demonstrated a sustained increase; however, only miR-466c-3p presented a sustained decrease 3 and 14 days after the injury. More interestingly, 4 of the miRNAs, including miR-18a, were upregulated on the 3rd day but were downregulated on the 14th day after injury. Some of these miRNAs target inflammatory-response genes in the early stage of injury, and others target neurotransmitter transport genes in the intermediate stages of injury. The altered miRNA expression pattern suggests that the MAPK and calcium signaling pathways are consistently involved in the injury response. Conclusions This analysis may facilitate the understanding of the time-specific altered expression of a large set of microRNAs in the spinal cord after brachial root avulsion. Electronic supplementary material The online version of this article (doi:10.1186/1471-2202-15-92) contains supplementary material, which is available to authorized users.
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Baig HA, Guarino BB, Lipschutz D, Winkelstein BA. Whole body vibration induces forepaw and hind paw behavioral sensitivity in the rat. J Orthop Res 2013; 31:1739-44. [PMID: 23832376 DOI: 10.1002/jor.22432] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 06/13/2013] [Indexed: 02/04/2023]
Abstract
Whole body vibration (WBV) has been linked to neck and back pain, but the biomechanical and physiological mechanisms responsible for its development and maintenance are unknown. A rodent model of WBV was developed in which rats were exposed to different WBV paradigms, either daily for 7 consecutive days (repeated WBV) or two single exposures at Day 0 and 7 (intermittent WBV). Each WBV session lasted for 30 min and was imposed at a frequency of 15 Hz and RMS platform acceleration of 0.56 ± 0.07 g. Changes in the withdrawal response of the forepaw and hind paw were measured, and were used to characterize the onset and maintenance of behavioral sensitivity. Accelerations and displacements of the rat and deformations in the cervical and lumbar spines were measured during WBV to provide mechanical context for the exposures. A decrease in withdrawal threshold was induced at 1 day after the first exposure in both the hind paw and forepaw. Repeated WBV exhibited a sustained reduction in withdrawal threshold in both paws and intermittent WBV induced a sustained response only in the forepaw. Cervical deformations were significantly elevated which may explain the more robust forepaw response. Findings suggest that a WBV exposure leads to behavioral sensitivity.
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Affiliation(s)
- Hassam A Baig
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 S. 33rd Street, Philadelphia, PA, 19104-6321
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18
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Zhang S, Nicholson KJ, Smith JR, Gilliland TM, Syré PP, Winkelstein BA. The roles of mechanical compression and chemical irritation in regulating spinal neuronal signaling in painful cervical nerve root injury. STAPP CAR CRASH JOURNAL 2013; 57:219-242. [PMID: 24435733 DOI: 10.4271/2013-22-0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Both traumatic and slow-onset disc herniation can directly compress and/or chemically irritate cervical nerve roots, and both types of root injury elicit pain in animal models of radiculopathy. This study investigated the relative contributions of mechanical compression and chemical irritation of the nerve root to spinal regulation of neuronal activity using several outcomes. Modifications of two proteins known to regulate neurotransmission in the spinal cord, the neuropeptide calcitonin gene-related peptide (CGRP) and glutamate transporter 1 (GLT-1), were assessed in a rat model after painful cervical nerve root injuries using a mechanical compression, chemical irritation or their combination of injury. Only injuries with compression induced sustained behavioral hypersensitivity (p≤0.05) for two weeks and significant decreases (p<0.037) in CGRP and GLT-1 immunoreactivity to nearly half that of sham levels in the superficial dorsal horn. Because modification of spinal CGRP and GLT-1 is associated with enhanced excitatory signaling in the spinal cord, a second study evaluated the electrophysiological properties of neurons in the superficial and deeper dorsal horn at day 7 after a painful root compression. The evoked firing rate was significantly increased (p=0.045) after compression and only in the deeper lamina. The painful compression also induced a significant (p=0.002) shift in the percentage of neurons in the superficial lamina classified as low- threshold mechanoreceptive (sham 38%; compression 10%) to those classified as wide dynamic range neurons (sham 43%; compression 74%). Together, these studies highlight mechanical compression as a key modulator of spinal neuronal signaling in the context of radicular injury and pain.
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Affiliation(s)
- Sijia Zhang
- Department of Bioengineering, University of Pennsylvania
| | | | - Jenell R Smith
- Department of Bioengineering, University of Pennsylvania
| | | | - Peter P Syré
- Department of Neurosurgery, University of Pennsylvania
| | - Beth A Winkelstein
- Departments of Bioengineering and Neurosurgery, University of Pennsylvania
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Activation profile of dorsal root ganglia Iba-1 (+) macrophages varies with the type of lesion in rats. Acta Histochem 2013; 115:840-50. [PMID: 23701965 DOI: 10.1016/j.acthis.2013.04.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 04/06/2013] [Accepted: 04/07/2013] [Indexed: 12/30/2022]
Abstract
The interactions between neurons, immune and immune-like glial cells can initiate the abnormal processes that underlie neuropathic pain. In the peripheral nervous system the resident macrophages may play an important role. In this study we investigated in experimental adult Sprague-Dawley rats how Iba-1 (ionized calcium binding adaptor molecule 1) (+) resident macrophages in the dorsal root ganglion (DRG) are activated after a spinal nerve ligation (SNL) or streptozotocin (STZ)-induced diabetes. The activation profile was defined by comparing the responses of resident macrophages against microglia in the spinal cord as they share a common origin. After SNL, the Iba-1 (+) macrophages in L5 DRG reached their activation peak 5 days later, clustered as satellite cells around large A-neurons, expressed the MHC-II marker, but did not show p-p38 and p-ERK1/2 activation and did not secrete IL-18. After STZ-induced diabetes, the Iba-1 (+) macrophages reached their activation peak 1 week later in L4 and L5 DRG, remained scattered between neurons, expressed the MHC-II marker only in L5 DRG, did not show p-p38 and p-ERK1/2 activation and did not secrete any of the investigated cytokines/chemokines. These responses suggest that depending on the type of lesion DRG Iba-1 (+) resident macrophages have different activation mechanisms, which are dissimilar to those in microglia.
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20
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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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21
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Hwang PY, Allen KD, Shamji MF, Jing L, Mata BA, Gabr MA, Huebner JL, Kraus VB, Richardson WJ, Setton LA. Changes in midbrain pain receptor expression, gait and behavioral sensitivity in a rat model of radiculopathy. Open Orthop J 2012; 6:383-91. [PMID: 22962568 PMCID: PMC3434701 DOI: 10.2174/1874325001206010383] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 07/25/2012] [Accepted: 07/31/2012] [Indexed: 02/07/2023] Open
Abstract
Intervertebral disc herniation may contribute to inflammatory processes that associate with radicular pain and motor deficits. Molecular changes at the affected dorsal root ganglion (DRG), spinal cord, and even midbrain, have been documented in rat models of radiculopathy or nerve injury. The objective of this study was to evaluate gait and the expression of key pain receptors in the midbrain in a rodent model of radiculopathy. Radiculopathy was induced by harvesting tail nucleus pulposus (NP) and placing upon the right L5 DRG in rats (NP-treated, n=12). Tail NP was discarded in sham-operated animals (n=12). Mechanical allodynia, weight-bearing, and gait were evaluated in all animals over time. At 1 and 4 weeks after surgery, astrocyte and microglial activation was tested in DRG sections. Midbrain sections were similarly evaluated for immunoreactivity to serotonin (5HT2B), mu-opioid (µ-OR), and metabotropic glutamate (mGluR4 and 5) receptor antibodies. NP-treated animals placed less weight on the affected limb 1 week after surgery and experienced mechanical hypersensitivity over the duration of the study. Astroctye activation was observed at DRGs only at 4 weeks after surgery. Findings for pain receptors in the midbrain of NP-treated rats included an increased expression of 5HT2B at 1, but not 4 weeks; increased expression of µ-OR and mGluR5 at 1 and 4 weeks (periaqueductal gray region only); and no changes in expression of mGluR4 at any point in this study. These observations provide support for the hypothesis that the midbrain responds to DRG injury with a transient change in receptors regulating pain responses.
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Affiliation(s)
- Priscilla Y Hwang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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22
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O'Neill S, Manniche C, Graven-Nielsen T, Arendt-Nielsen L. Generalized deep-tissue hyperalgesia in patients with chronic low-back pain. Eur J Pain 2012; 11:415-20. [PMID: 16815054 DOI: 10.1016/j.ejpain.2006.05.009] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2005] [Revised: 04/24/2006] [Accepted: 05/23/2006] [Indexed: 11/16/2022]
Abstract
Some chronic painful conditions including e.g. fibromyalgia, whiplash associated disorders, endometriosis, and irritable bowel syndrome are associated with generalized musculoskeletal hyperalgesia. The aim of the present study was to determine whether generalized deep-tissue hyperalgesia could be demonstrated in a group of patients with chronic low-back pain with intervertebral disc herniation. Twelve patients with MRI confirmed lumbar intervertebral disc herniation and 12 age and sex matched controls were included. Subjects were exposed to quantitative nociceptive stimuli to the infraspinatus and anterior tibialis muscles. Mechanical pressure (thresholds and supra-threshold) and injection of hypertonic saline (pain intensity, duration, distribution) were used. Pain intensity to experimental stimuli was assessed on a visual analogue scale (VAS). Patients demonstrated significantly higher pain intensity (VAS), duration, and larger areas of pain referral following saline injection in both infraspinatus and tibialis anterior. The patients rated significantly higher pain intensity to supra-threshold mechanical pressure stimulation in both muscles. In patients, the pressure pain-threshold was lower in the anterior tibialis muscle compared to controls. In conclusion, generalized deep-tissue hyperalgesia was demonstrated in chronic low-back pain patients with radiating pain and MRI confirmed intervertebral disc herniation, suggesting that this central sensitization should also be addressed in the pain management regimes.
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Affiliation(s)
- Søren O'Neill
- Human Locomotion Science, University of Southern Denmark, Odense, Denmark
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23
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Chang YW, Winkelstein BA. Schwann Cell Proliferation and Macrophage Infiltration Are Evident at Day 14 after Painful Cervical Nerve Root Compression in the Rat. J Neurotrauma 2011; 28:2429-38. [DOI: 10.1089/neu.2011.1918] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Yu-Wen Chang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Beth A. Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania
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Kietrys DM, Barr AE, Barbe MF. Exposure to repetitive tasks induces motor changes related to skill acquisition and inflammation in rats. J Mot Behav 2011; 43:465-76. [PMID: 22087754 DOI: 10.1080/00222895.2011.627897] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The authors elucidate exposure-response relationships between repetitive tasks, inflammation, and motor changes with work-related musculoskeletal disorders. Using a rat model of reaching and handle pulling, they examined effects of performing a high-repetition, low-force (HRLF); low-repetition, high-force (LRHF); or high-repetition, high-force (HRHF) task (2 hr/day, 3 days/week, 12 weeks) on reach rate and force, percentage of successful reaches, duration of participation, and grip strength. Reach rate and reach force improved with HRLF, and percentage success increased in all groups in Week 9, and in HRLF and HRHF in Week 12, indicative of skill acquisition. Duration and grip strength showed force-dependent declines with task performance. A subset of HRHF rats received ibuprofen in Weeks 5-12. Ibuprofen significantly improved reach rate, reach force, and duration in treated rats, indicative of an inflammatory influence on reach performance. Ibuprofen improved percentage of successful reaches in Week 9, although this increase was not sustained. However, declines in grip strength, a nocifensive behavior, were not prevented by ibuprofen. Examination of cervical spinal cords of untreated and ibuprofen treated HRHF rats showed increased IL-1beta, an inflammatory cytokine, in neurons. These findings suggest that only a preventive intervention could have addressed all motor declines.
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Affiliation(s)
- David M Kietrys
- Department of Rehabilitation and Movement Sciences, University of Medicine and Dentistry of New Jersey, School of Health Related Professions, Stratford, New Jersey, USA
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25
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Chew DJ, Carlstedt T, Shortland PJ. A comparative histological analysis of two models of nerve root avulsion injury in the adult rat. Neuropathol Appl Neurobiol 2011; 37:613-32. [DOI: 10.1111/j.1365-2990.2011.01176.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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26
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Hains LE, Loram LC, Weiseler JL, Frank MG, Bloss EB, Sholar P, Taylor FR, Harrison JA, Martin TJ, Eisenach JC, Maier SF, Watkins LR. Pain intensity and duration can be enhanced by prior challenge: initial evidence suggestive of a role of microglial priming. THE JOURNAL OF PAIN 2011; 11:1004-14. [PMID: 20434956 DOI: 10.1016/j.jpain.2010.01.271] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 12/12/2009] [Accepted: 01/25/2010] [Indexed: 01/09/2023]
Abstract
UNLABELLED Activation of spinal microglia and consequent release of proinflammatory mediators facilitate pain. Under certain conditions, responses of activated microglia can become enhanced. Enhanced microglial production of proinflammatory products may result from priming (sensitization), similar to macrophage priming. We hypothesized that if spinal microglia were primed by an initial inflammatory challenge, subsequent challenges may create enhanced pain. Here, we used a "two-hit" paradigm using 2 successive challenges, which affect overlapping populations of spinal microglia, presented 2 weeks apart. Mechanical allodynia and/or activation of spinal glia were assessed. Initially, laparotomy preceded systemic lipopolysaccharide (LPS). Prior laparotomy caused prolonged microglial (not astrocyte) activation plus enhanced LPS-induced allodynia. In this "two-hit" paradigm, minocycline, a microglial activation inhibitor, significantly reduced later exaggerated pain induced by prior surgery when minocycline was administered intrathecally for 5 days starting either at the time of surgery or 5 days before LPS administration. To test generality of the priming effect, subcutaneous formalin preceded intrathecal HIV-1 gp120, which activates spinal microglia and causes robust allodynia. Prior formalin enhanced intrathecal gp120-induced allodynia, suggesting that microglial priming is not limited to laparotomy and again supporting a spinal site of action. Therefore, spinal microglial priming may increase vulnerability to pain enhancement. PERSPECTIVE Spinal microglia may become "primed" (sensitized) following their activation by disparate forms of peripheral trauma/inflammation. As a result, such primed microglia may overrespond to subsequent challenges, thereby enhancing pain intensity and duration.
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Affiliation(s)
- Leah E Hains
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado 80309-0345, USA
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Inflammatory cytokine and chemokine expression is differentially modulated acutely in the dorsal root ganglion in response to different nerve root compressions. Spine (Phila Pa 1976) 2011; 36:197-202. [PMID: 20714281 DOI: 10.1097/brs.0b013e3181ce4f4d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Inflammatory proteins were quantified in bilateral dorsal root ganglions (DRGs) at 1 hour and 1 day using a multiplexed assay after 2 different unilateral nerve root compression injuries. OBJECTIVE To quantify cytokines and a chemokine in the DRG after nerve root compression with and without a chemical injury to determine contributing inflammatory factors in the DRG that may mediate radicular nociception in clinically relevant nerve root pathologies. SUMMARY OF BACKGROUND DATA Inflammatory cytokines are known to relate to the behavioral hypersensitivity induced after injuries to the nerve root. However, the relative expression of these proteins in the DRG after cervical nerve root compression are not known. METHODS The right C7 nerve root underwent transient compression (10 gf) or transient compression with a chemical irritation (10 gf + chr). The chemical injury was also given alone (chr), and the nerve root was exposed (sham), providing 2 types of controls. Mechanical allodynia was measured to assess behavioral outcomes. Interleukin (IL)-1b, IL-6, tumor necrosis factor-a, and macrophage inflammatory protein 3 (MIP3) were quantified in bilateral DRGs at 1 hour and 1 day using a multiplexed assay. RESULTS Ipsilateral allodynia at day 1 after 10 gf + chr was significantly increased over both 10 gf and chr (P < 0.049). Cytokines and MIP3 were not statistically increased over sham at 1 hour. By day 1 after 10 gf + chr, all proteins (IL-1β, IL-6, tumor necrosis factor-a, MIP3) were significantly increased over both normal and sham in the ipsilateral DRG (P < 0.036), and the cytokines were also significantly increased over chr (P < 0.029). Despite allodynia at day 1, cytokines at that time were not increased over normal or sham after either 10 gf or chr. CONCLUSION Nerve root compression alone may not be sufficient to induce early increases in proinflammatory cytokines in the DRG after radiculopathy and this early protein response may not be directly responsible for nociception in this type of injury.
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Moalem-Taylor G, Li M, Allbutt HN, Wu A, Tracey DJ. A preconditioning nerve lesion inhibits mechanical pain hypersensitivity following subsequent neuropathic injury. Mol Pain 2011; 7:1. [PMID: 21205324 PMCID: PMC3022745 DOI: 10.1186/1744-8069-7-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 01/05/2011] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND A preconditioning stimulus can trigger a neuroprotective phenotype in the nervous system - a preconditioning nerve lesion causes a significant increase in axonal regeneration, and cerebral preconditioning protects against subsequent ischemia. We hypothesized that a preconditioning nerve lesion induces gene/protein modifications, neuronal changes, and immune activation that may affect pain sensation following subsequent nerve injury. We examined whether a preconditioning lesion affects neuropathic pain and neuroinflammation after peripheral nerve injury. RESULTS We found that a preconditioning crush injury to a terminal branch of the sciatic nerve seven days before partial ligation of the sciatic nerve (PSNL; a model of neuropathic pain) induced a significant attenuation of pain hypersensitivity, particularly mechanical allodynia. A preconditioning lesion of the tibial nerve induced a long-term significant increase in paw-withdrawal threshold to mechanical stimuli and paw-withdrawal latency to thermal stimuli, after PSNL. A preconditioning lesion of the common peroneal induced a smaller but significant short-term increase in paw-withdrawal threshold to mechanical stimuli, after PSNL. There was no difference between preconditioned and unconditioned animals in neuronal damage and macrophage and T-cell infiltration into the dorsal root ganglia (DRGs) or in astrocyte and microglia activation in the spinal dorsal and ventral horns. CONCLUSIONS These results suggest that prior exposure to a mild nerve lesion protects against adverse effects of subsequent neuropathic injury, and that this conditioning-induced inhibition of pain hypersensitivity is not dependent on neuroinflammation in DRGs and spinal cord. Identifying the underlying mechanisms may have important implications for the understanding of neuropathic pain due to nerve injury.
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Affiliation(s)
- Gila Moalem-Taylor
- School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
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Nociceptors, Pain, and Spinal Manipulation. Pain Manag 2011. [DOI: 10.1016/b978-1-4377-0721-2.00137-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Elliott M, Barr A, Clark B, Wade C, Barbe M. Performance of a repetitive task by aged rats leads to median neuropathy and spinal cord inflammation with associated sensorimotor declines. Neuroscience 2010; 170:929-41. [DOI: 10.1016/j.neuroscience.2010.07.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 07/21/2010] [Accepted: 07/21/2010] [Indexed: 12/30/2022]
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Bertilson BC, Brosjö E, Billing H, Strender LE. Assessment of nerve involvement in the lumbar spine: agreement between magnetic resonance imaging, physical examination and pain drawing findings. BMC Musculoskelet Disord 2010; 11:202. [PMID: 20831785 PMCID: PMC2944219 DOI: 10.1186/1471-2474-11-202] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 09/10/2010] [Indexed: 11/19/2022] Open
Abstract
Background Detection of nerve involvement originating in the spine is a primary concern in the assessment of spine symptoms. Magnetic resonance imaging (MRI) has become the diagnostic method of choice for this detection. However, the agreement between MRI and other diagnostic methods for detecting nerve involvement has not been fully evaluated. The aim of this diagnostic study was to evaluate the agreement between nerve involvement visible in MRI and findings of nerve involvement detected in a structured physical examination and a simplified pain drawing. Methods Sixty-one consecutive patients referred for MRI of the lumbar spine were - without knowledge of MRI findings - assessed for nerve involvement with a simplified pain drawing and a structured physical examination. Agreement between findings was calculated as overall agreement, the p value for McNemar's exact test, specificity, sensitivity, and positive and negative predictive values. Results MRI-visible nerve involvement was significantly less common than, and showed weak agreement with, physical examination and pain drawing findings of nerve involvement in corresponding body segments. In spine segment L4-5, where most findings of nerve involvement were detected, the mean sensitivity of MRI-visible nerve involvement to a positive neurological test in the physical examination ranged from 16-37%. The mean specificity of MRI-visible nerve involvement in the same segment ranged from 61-77%. Positive and negative predictive values of MRI-visible nerve involvement in segment L4-5 ranged from 22-78% and 28-56% respectively. Conclusion In patients with long-standing nerve root symptoms referred for lumbar MRI, MRI-visible nerve involvement significantly underestimates the presence of nerve involvement detected by a physical examination and a pain drawing. A structured physical examination and a simplified pain drawing may reveal that many patients with "MRI-invisible" lumbar symptoms need treatment aimed at nerve involvement. Factors other than present MRI-visible nerve involvement may be responsible for findings of nerve involvement in the physical examination and the pain drawing.
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Affiliation(s)
- Bo C Bertilson
- Center for Family and Community Medicine, Karolinska Institutet, 141 83 Huddinge, Stockholm, Sweden.
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Gao YJ, Xu ZZ, Liu YC, Wen YR, Decosterd I, Ji RR. The c-Jun N-terminal kinase 1 (JNK1) in spinal astrocytes is required for the maintenance of bilateral mechanical allodynia under a persistent inflammatory pain condition. Pain 2010; 148:309-319. [PMID: 20022176 DOI: 10.1016/j.pain.2009.11.017] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2009] [Revised: 09/22/2009] [Accepted: 11/16/2009] [Indexed: 12/20/2022]
Abstract
Peripheral inflammation induces persistent central sensitization characterized by mechanical allodynia and heat hyperalgesia that are mediated by distinct mechanisms. Compared to well-demonstrated mechanisms of heat hyperalgesia, mechanisms underlying the development of mechanical allodynia and contralateral pain are incompletely known. In this study, we investigated the distinct role of spinal JNK in heat hyperalgesia, mechanical allodynia, and contralateral pain in an inflammatory pain model. Intraplantar injection of complete Freund's adjuvant (CFA) induced bilateral mechanical allodynia but unilateral heat hyperalgesia. CFA also induced a bilateral activation (phosphorylation) of JNK in the spinal cord, and the phospho JNK1 (pJNK1) levels were much higher than that of pJNK2. Notably, both pJNK and JNK1 were expressed in GFAP-positive astrocytes. Intrathecal infusion of a selective peptide inhibitor of JNK, D-JNKI-1, starting before inflammation via an osmotic pump, reduced CFA-induced mechanical allodynia in the maintenance phase but had no effect on CFA-induced heat hyperalgesia. A bolus intrathecal injection of D-JNKI-1 or SP600126, a small molecule inhibitor of JNK also reversed mechanical allodynia bilaterally. In contrast, peripheral (intraplantar) administration of D-JNKI-1 reduced the induction of CFA-induced heat hyperalgesia but did not change mechanical allodynia. Finally, CFA-induced bilateral mechanical allodynia was attenuated in mice lacking JNK1 but not JNK2. Taken together, our data suggest that spinal JNK, in particular JNK1 plays an important role in the maintenance of persistent inflammatory pain. Our findings also reveal a unique role of JNK1 and astrocyte network in regulating tactile allodynia and contralateral pain.
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Affiliation(s)
- Yong-Jing Gao
- Sensory Plasticity Laboratory, Pain Research Center, Department of Anesthesiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA Institute of Nautical Medicine, Nantong University, Nantong 226001, China Department of Anesthesiology, Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan Anesthesiology Pain Research Group, Anesthesiology Department, University Hospital Center and University of Lausanne CH-1011 Lausanne, Switzerland Department of Cell Biology and Morphology, University of Lausanne, CH-1005 Lausanne, Switzerland
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The mirror-image pain: an unclered phenomenon and its possible mechanism. Neurosci Biobehav Rev 2009; 34:528-32. [PMID: 19883682 DOI: 10.1016/j.neubiorev.2009.10.011] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 09/24/2009] [Accepted: 10/22/2009] [Indexed: 01/04/2023]
Abstract
The contralateral allodynia to an injury has been described both in humans and various models of neuropathic and inflammatory pain in rats. In this article, the occurrence of mirror-image pain (MIP) in human beings and animals were reviewed and the possible mechanism of MIP reported was summarized. Last, according to the literature published, we raise some speculation about the possible mechanism underlying MIP.
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Kitab SA, Miele VJ, Lavelle WF, Benzel EC. PATHOANATOMIC BASIS FOR STRETCH-INDUCED LUMBAR NERVE ROOT INJURY WITH A REVIEW OF THE LITERATURE. Neurosurgery 2009; 65:161-7; discussion 167-8. [DOI: 10.1227/01.neu.0000347002.67982.8f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Abstract
OBJECTIVE
Persistent pain originating from a dysfunctional lumbar motion segment poses significant challenges in the clinical arena. Although the predominance of the existing spine literature has addressed nerve root compression as the principal cause of pain, it is equally likely that a stretch mechanism may be responsible for all or part of the pathology.
METHODS
The literature supporting the role of stretch damage as a primary cause of nerve root injury and pain was systematically reviewed. Pathoanatomic considerations between nerve roots and juxtaposed environment are described and correlated with the available literature. Potential anatomic relationships that may lead to stretch-induced injury are delineated.
RESULTS
A dynamic lumbar functional spinal unit that encloses a tethered nerve root can create significant stretch and/or compression. This phenomenon may be present in a variety of pathological conditions. These include anterior, posterior, and rotatory olisthesis as well as degenerative conditions such as the loss of disc interspace height and frank multisegment spinal deformity. Although numerous studies have demonstrated that stretch can result in nerve damage, the pathophysiology that may associate nerve stretch with chronic pain has yet to be determined.
CONCLUSION
The current literature concerning stretch-related injury to nerve roots is reviewed, and a conceptual framework for its diagnosis and treatment is proposed and graphically illustrated using cadaveric specimens. The dynamic biomechanical and functional interrelationships between neural structures and adjacent connective tissue elements are particularly important in the face of spinal deformity.
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Affiliation(s)
| | - Vincent J. Miele
- Center for Spine Health, Neurological Institute, Cleveland Clinic, Cleveland, Ohio
| | - William F. Lavelle
- Center for Spine Health, Neurological Institute, Cleveland Clinic, Cleveland, Ohio
| | - Edward C. Benzel
- Department of Neurosurgery, Center for Spine Health, Neurological Institute, Cleveland Clinic, Cleveland, Ohio
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Elliott MB, Barr AE, Clark BD, Amin M, Amin S, Barbe MF. High force reaching task induces widespread inflammation, increased spinal cord neurochemicals and neuropathic pain. Neuroscience 2008; 158:922-31. [PMID: 19032977 DOI: 10.1016/j.neuroscience.2008.10.050] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 10/27/2008] [Accepted: 10/29/2008] [Indexed: 01/30/2023]
Abstract
Repetitive strain injuries (RSI), which include several musculoskeletal disorders and nerve compression injuries, are associated with performance of repetitive and forceful tasks. In this study, we examined in young, adult Sprague-Dawley rats, the effects of performing a voluntary, moderate repetition, high force (MRHF; nine reaches/min; 60% maximum pulling force) task for 12 weeks on motor behavior and nerve function, inflammatory responses in forearm musculoskeletal and nerve tissues and serum, and neurochemical immunoexpression in cervical spinal cord dorsal horns. We observed no change in reach rate, but reduced voluntary participation and grip strength in week 12, and increased cutaneous sensitivity in weeks 6 and 12, the latter indicative of mechanical allodynia. Nerve conduction velocity (NCV) decreased 15% in the median nerve in week 12, indicative of low-grade nerve compression. ED-1 cells increased in distal radius and ulna in week 12, and in the median nerve and forearm muscles and tendons in weeks 6 and 12. Cytokines IL-1alpha, IL-1beta, TNF-alpha, and IL-10 increased in distal forearm bones in week 12, while IL-6 increased in tendon in week 12. However, serum analysis revealed only increased TNF-alpha in week 6 and macrophage inflammatory protein 3a (MIP3a) in weeks 6 and 12. Lastly, Substance P and neurokinin-1 were both increased in weeks 6 and 12 in the dorsal horns of cervical spinal cord segments. These results show that a high force, but moderate repetition task, induced declines in motor and nerve function as well as peripheral and systemic inflammatory responses (albeit the latter was mild). The peripheral inflammatory responses were associated with signs of central sensitization (mechanical allodynia and increased neurochemicals in spinal cord dorsal horns).
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Affiliation(s)
- M B Elliott
- Department of Physical Therapy, Temple University, 3307 North Broad Street, Philadelphia, PA 19140, USA.
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Nie H, Graven-Nielsen T, Arendt-Nielsen L. Spatial and temporal summation of pain evoked by mechanical pressure stimulation. Eur J Pain 2008; 13:592-9. [PMID: 18926745 DOI: 10.1016/j.ejpain.2008.07.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 05/14/2008] [Accepted: 07/27/2008] [Indexed: 12/22/2022]
Abstract
Chronic pain patients often suffer from widespread and long lasting pain. The integrative effect of combined spatial and temporal summation on pain intensity has not been quantitatively tested. The present study was designed to investigate: (1) if the size of the stimulation area would facilitate the temporal summation of pain to repetitive pressure stimulation, and (2) if temporal summation is effective when stimulating separated sites, repetitively. Twenty healthy male subjects participated in this study. The test sites were located on the bilateral upper trapezius and tibialis anterior muscles. The ten stimuli (each with a duration of 1s) were applied to a single site at three inter-stimulus intervals (ISI: 1, 5, 30s) using five different probe sizes (0.5, 1, 2, 4 and 8cm(2)). The stimulation intensity was equal to the pressure pain threshold (PPT) determined for each probe size. Similar repetitive stimulations at two inter-stimulus intervals (5s and 30s) using two sizes of probes (0.5cm(2) and 2cm(2)) were applied to ten separate sites. The PPT at the trapezius muscle decreased significantly with the increase in stimulus area from 0.5cm(2) to 8cm(2) (P<0.001) due to spatial summation. Temporal summation of pain was evoked by repetitive pressure stimuli on the same site for all ISI and was more pronounced at 5s and 30s ISI with larger probe areas (2, 4, and 8cm(2)) compared to smaller probe areas. There was no temporal summation of pain to stimuli with ISI 5 and 30s when stimulating the separated sites. The current study indicated that spatial summation facilitated the temporal summation of pain for stimuli given at 5s and 30s ISI. The combination of temporal and spatial integration of nociceptive input facilitates the pain intensity, suggesting that temporal summation is clinically relevant in conditions with widespread pain.
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Affiliation(s)
- HongLing Nie
- Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Rothman SM, Huang Z, Lee KE, Weisshaar CL, Winkelstein BA. Cytokine mRNA expression in painful radiculopathy. THE JOURNAL OF PAIN 2008; 10:90-9. [PMID: 18848809 DOI: 10.1016/j.jpain.2008.07.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 07/18/2008] [Accepted: 07/29/2008] [Indexed: 01/01/2023]
Abstract
UNLABELLED Inflammatory cytokines contribute to lumbar radiculopathy. Regulation of cytokines for transient cervical injuries, with or without longer-lasting inflammation, remains to be defined. The C7 root in the rat underwent compression (10gf), chromic gut suture exposure (chr), or their combination (10gf+chr). Ipsilateral C7 spinal cord and dorsal root ganglia (DRG) were harvested at 1 hour after injury for real-time PCR analysis of IL-1beta, IL-6, and TNF-alpha. Cytokine mRNA increased after all 3 injuries. TNF-alpha mRNA in the DRG was significantly increased over sham after 10gf+chr (P = .026). Spinal IL-1beta was significantly increased over sham after 10gf and 10gf+chr (P < .024); IL-6 was significantly increased after 10gf+chr (P < .024). In separate studies, the soluble TNF-alpha receptor was administered at injury and again at 6 hours in all injury paradigms. Allodynia was assessed and tissue samples were harvested for cytokine PCR. Allodynia significantly decreased with receptor administration for 10gf and 10gf+chr (P < .005). Treatment also significantly decreased IL-1beta and TNF-alpha mRNA in the DRG for 10gf+chr (P < .028) at day 1. Results indicate an acute, robust cytokine response in cervical nerve root injury with varying patterns, dependent on injury type, and that early increases in TNF-alpha mRNA in the DRG may drive pain-related signaling for transient cervical injuries. PERSPECTIVE Inflammatory cytokine mRNA in the DRG and spinal cord are defined after painful cervical nerve root injury. Studies describe a role for TNF-alpha in mediating behavioral sensitivity and inflammatory cytokines in transient painful radiculopathy. Results outline an early response of inflammatory cytokine upregulation in cervical pain.
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Affiliation(s)
- Sarah M Rothman
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6321, USA
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Sasaki M, Abekura M, Morris S, Kataoka Y, Yoshimura K, Ninomiya K, Iwatsuki K, Yoshimine T. Allodynia corresponding to the levels of cervical cord injury treated by surgical decompression: a report of 3 cases. SURGICAL NEUROLOGY 2008; 72:281-5; discussion 285. [PMID: 18614217 DOI: 10.1016/j.surneu.2008.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Accepted: 05/12/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND The role and timing of surgical decompression for SCI remains controversial, when the surgical outcomes are evaluated only by neurologic recovery. Other than neurologic deficits, severe pain after SCI is a significant problem, deteriorating the patient's activity of daily living. In the present report, allodynia of patients' upper limbs caused by cervical SCI was treated successfully by surgical decompression. CASE DESCRIPTIONS Three male patients received cervical SCI through minor accidents. They complained of allodynia and motor dysfunction at the spinal level compressed by preexisting lower cervical spondylosis, but they lacked symptoms or neurologic abnormalities below that spinal level. Severe pain was induced by soft touch or exposure to water at room temperature preoperatively. Surgical decompressions of the spinal cord and nerve roots were performed between 20 and 83 days (mean, 48.7 days) after the SCI. Allodynia was reduced in all patients immediately after surgery. Pain induced by soft touch disappeared within 4 days of operations, whereas pain by water exposure diminished within months. Recurrence of allodynia has not been observed in patients at least until the last follow-up, within periods ranging from 15 to 39 months (average, 26 months). The mean preoperative VAS was 6.0, and this improved to 2.2 at 1 month and 0.8 at the final follow-up. CONCLUSION We propose that patients with SCI with allodynia and motor dysfunction of the upper limbs related only to the compressed spinal levels are potentially treatable by surgical decompression.
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Affiliation(s)
- Manabu Sasaki
- Department of Neurosurgery and Spine Surgery, Yukioka Hospital, Osaka 530-0021, Japan.
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Contralateral neuropathic pain and neuropathology in dorsal root ganglion and spinal cord following hemilateral nerve injury in rats. Spine (Phila Pa 1976) 2008; 33:1344-51. [PMID: 18496347 DOI: 10.1097/brs.0b013e3181733188] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN The contralateral pain-related behavioral and immunohistochemical changes after hemilateral spinal nerve injury in rats were investigated. OBJECTIVES We evaluated the longitudinal changes in contralateral mechanical allodynia, expression of tumor necrosis factor (TNF)-alpha and glial fibrillary acidic protein (GFAP)-positive satellite cells in the contralateral dorsal root ganglion (DRG), and expression of astrocytes and microglia in the contralateral spinal dorsal horn after hemilateral spinal nerve injury in rats. SUMMARY OF BACKGROUND DATA In previous studies, hemilateral nerve injury has sometimes induced contralateral neuropathic pain. TNF-alpha expression and glial cell reactions in the DRG and spinal cord play an important role in the neuropathic pain state, and TNF-alpha is released from glial cells in the nervous system. METHODS Adult male Sprague-Dawley rats were used. The spinal L5 nerve distal to the DRG was crushed once for 3 seconds. At days 2, 7, 14, and 21 after surgery, mechanical allodynia was determined in bilateral hind paws by the von Frey test. Expression of TNF-alpha and GFAP in bilateral L5 DRGs and expression of GFAP and ionized calcium-binding adaptor molecule-1 (Iba-1) in bilateral L5 spinal dorsal horns were studied using immunohistochemistry and immunoblotting. RESULTS Mechanical withdrawal threshold of the ipsilateral hind paw was significantly decreased for 21 days. Conversely, mechanical withdrawal threshold of the contralateral hind paw was significantly decreased from 5 to 10 g for 7 days, and was <5 g at days 14 and 21. TNF-alpha expression and GFAP-positive satellite cells in the contralateral DRG significantly increased from day 7 to day 21. In the contralateral spinal dorsal horn, GFAP-positive astrocytes significantly increased for 21 days, but Iba-1 was not significant. CONCLUSION These results suggest that contralateral mechanical allodynia induced by hemilateral spinal nerve injury is associated with upregulation of satellite cells and TNF-alpha in the contralateral DRG. In addition, our results suggest that spinal astrocytes play an important role in these contralateral changes.
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Schreiber KL, Beitz AJ, Wilcox GL. Activation of spinal microglia in a murine model of peripheral inflammation-induced, long-lasting contralateral allodynia. Neurosci Lett 2008; 440:63-7. [PMID: 18541374 DOI: 10.1016/j.neulet.2008.05.044] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2008] [Revised: 05/02/2008] [Accepted: 05/07/2008] [Indexed: 12/26/2022]
Abstract
Increased sensitivity contralateral to an injury has been described in humans and in various models of neuropathic pain in rats. The mechanism underlying contralateral hypersensitivity is as yet unclear, although previous studies have implicated involvement of both spinal neurons and glia. We describe the development of a temporally delayed, robust and long-lasting contralateral allodynia in mice after hindpaw injection with 4% carrageenan. Both ipsilateral and contralateral allodynia could be inhibited temporarily by intrathecally administered morphine, clonidine, or neostigmine. The delayed development of contralateral allodynia correlated with an increase in OX-42, but not GFAP immunoreactivity in the contralateral dorsal horn. Furthermore, intrathecal treatment with minocycline inhibited the development of contralateral allodynia, suggesting that microglial activation plays a key role in contralateralization, and may be a potential target for clinical intervention after injury or inflammation has occurred, to eliminate the subsequent development of extraterritorial pain.
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Affiliation(s)
- Kristin L Schreiber
- Department of Anesthesiology, University of Minnesota, 321 Church Street, Minneapolis, MN 55455, United States.
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Hubbard RD, Chen Z, Winkelstein BA. Transient cervical nerve root compression modulates pain: load thresholds for allodynia and sustained changes in spinal neuropeptide expression. J Biomech 2007; 41:677-85. [PMID: 17976629 DOI: 10.1016/j.jbiomech.2007.09.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 09/24/2007] [Accepted: 09/25/2007] [Indexed: 10/22/2022]
Abstract
Nerve root compression produces chronic pain and altered spinal neuropeptide expression. This study utilized controlled transient loading in a rat model of painful cervical nerve root compression to investigate the dependence of mechanical allodynia on load magnitude. Injury loads (0-110mN) were applied quasistatically using a customized loading device, and load thresholds to produce maintained mechanical allodynia were defined. Bilateral spinal expression of substance P (SP) and calcitonin gene-related peptide (CGRP) was assessed 7 days following compression using immunohistochemistry to determine relationships between these neuropeptides and compression load. A three-segment change point model was implemented to model allodynia responses and their relationship to load. Load thresholds were defined at which ipsilateral and contralateral allodynia were produced and sustained. The threshold for increased allodynia was lowest for acute (day 1) ipsilateral responses (26.29mN), while thresholds for allodynia on day 7 were similar for the ipsilateral (38.16mN) and contralateral forepaw (38.26mN). CGRP, but not SP, significantly decreased with load; the thresholds for ipsilateral and contralateral CGRP decreases corresponded to 19.52 and 24.03mN, respectively. These thresholds suggest bilateral allodynia may be mediated by spinal mechanisms, and that these mechanisms depend on the magnitude of load.
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Affiliation(s)
- Raymond D Hubbard
- Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd Street, Philadelphia, PA 19104-6321, USA
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Grape S, Tramèr MR. Do we need preemptive analgesia for the treatment of postoperative pain? Best Pract Res Clin Anaesthesiol 2007; 21:51-63. [PMID: 17489219 DOI: 10.1016/j.bpa.2006.11.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Preemptive analgesia means that an analgesic intervention is started before the noxious stimulus arises in order to block peripheral and central nociception. This afferent blockade of nociceptive impulses is maintained throughout the intra-operative and post-operative period. The goals of preemptive analgesia are, first, to decrease acute pain after tissue injury, second, to prevent pain-related pathologic modulation of the central nervous system, and third, to inhibit the persistence of postoperative pain and the development of chronic pain. So far, the promising results from animal models have not been translated into clinical practice. Therefore, clinicians should rely on conventional anaesthetic and analgesic methods with proven efficacy, i.e. a multimodal approach including the combination of strong opioids, non-opioid analgesics, and peripheral or neuraxial local anaesthetics that act at different sites of the pain pathways.
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Affiliation(s)
- Sina Grape
- Division of Anaesthesiology, Geneva University Hospitals, CH- 12 11 Geneva, Switzerland.
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Bove GM, Swenson RS. Nociceptors and Peripheral Sources of Pain. Pain Manag 2007. [DOI: 10.1016/b978-0-7216-0334-6.50133-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Zhang Y, Kerns JM, Anderson DG, Lee YS, Chen EY, Tannoury C, An HS. Sensory neurons and fibers from multiple spinal cord levels innervate the rabbit lumbar disc. Am J Phys Med Rehabil 2006; 85:865-71. [PMID: 17079958 DOI: 10.1097/01.phm.0000242633.41202.ef] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To establish the neurotransmission pathway from the lumbar L5/6 intervertebral disc (IVD) to the spinal cord in the rabbit. DESIGN Fluorogold particles injected into the posterior portion of the rabbit L5/6 IVD were traced by examining gold-positive neurons and fibers in the dorsal root ganglion (DRG) and spinal cord at various root levels. RESULTS Fluorogold-labeled neurons were observed bilaterally in primary afferent DRG neurons from the L3 through L5 segments; a small number of gold-labeled neurons were found at the L1 level. Fluorogold-labeled neurons were predominantly present in the ipsilateral DRG (the side of the injection) at the L5 level, but they were more equally distributed (on both sides) at the L4 and L3 levels. In the posterior horn of the spinal cord, Fluorogold particles were found in nerve fibers as rostral as the T12 level. CONCLUSIONS Our study has shown that Fluorogold particles injected into the rabbit L5/6 IVD are taken up by primary sensory neurons in the DRGs and primary sensory fibers in the posterior horn of the spinal cord at multiple levels. This diffuse innervation pattern of the lumbar disc may help explain why discogenic back pain in humans is often poorly localized.
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Affiliation(s)
- Yejia Zhang
- Department of Orthopedic Surgery, Rush University Medical Center, Chicago, Illinois, USA
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Light AR, Wu Y, Hughen RW, Guthrie PB. Purinergic receptors activating rapid intracellular Ca increases in microglia. ACTA ACUST UNITED AC 2005; 2:125-138. [PMID: 16652167 PMCID: PMC1424667 DOI: 10.1017/s1740925x05000323] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We provide both molecular and pharmacological evidence that the metabotropic, purinergic, P2Y(6), P2Y(12) and P2Y(13) receptors and the ionotropic P2X(4) receptor contribute strongly to the rapid calcium response caused by ATP and its analogues in mouse microglia. Real-time PCR demonstrates that the most prevalent P2 receptor in microglia is P2Y(6) followed, in order, by P2X(4), P2Y(12), and P2X(7) = P2Y(13). Only very small quantities of mRNA for P2Y(1), P2Y(2), P2Y(4), P2Y(14), P2X(3) and P2X(5) were found. Dose-response curves of the rapid calcium response gave a potency order of: 2MeSADP>ADP=UDP=IDP=UTP>ATP>BzATP, whereas A2P4 had little effect. Pertussis toxin partially blocked responses to 2MeSADP, ADP and UDP. The P2X(4) antagonist suramin, but not PPADS, significantly blocked responses to ATP. These data indicate that P2Y(6), P2Y(12), P2Y(13) and P2X receptors mediate much of the rapid calcium responses and shape changes in microglia to low concentrations of ATP, presumably at least partly because ATP is rapidly hydrolyzed to ADP. Expression of P2Y(6), P2Y(12) and P2Y(13) receptors appears to be largely glial in the brain, so that peripheral immune cells and CNS microglia share these receptors. Thus, purinergic, metabotropic, P2Y(6), P2Y(12), P2Y(13) and P2X(4) receptors might share a role in the activation and recruitment of microglia in the brain and spinal cord by widely varying stimuli that cause the release of ATP, including infection, injury and degeneration in the CNS, and peripheral tissue injury and inflammation which is signaled via nerve signaling to the spinal cord.
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Affiliation(s)
- Alan R. Light
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
- Please address correspondence to: Alan R. Light, Department of Anesthesiology, University of Utah, 3C444 SOM, 3oN. 1900 E, Salt Lake City, UT 84132-2304, USA, phone: +1 801 581 6393, fax: +1 801 581 4367,
| | - Ying Wu
- Oral Biology Program, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27510, USA
| | - Ronald W. Hughen
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Peter B. Guthrie
- Scientific Review Administrator, Center for Scientific Review, National Institutes of Health, 6701 Rockledge Drive, Room 4142 Msc 7850, Bethesda, MD 20892-7850, USA
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Zhang RX, Liu B, Wang L, Ren K, Qiao JT, Berman BM, Lao L. Spinal glial activation in a new rat model of bone cancer pain produced by prostate cancer cell inoculation of the tibia. Pain 2005; 118:125-36. [PMID: 16154703 DOI: 10.1016/j.pain.2005.08.001] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Revised: 07/19/2005] [Accepted: 08/01/2005] [Indexed: 01/23/2023]
Abstract
Studies suggest that astrocytes and microglia in the spinal cord are involved in the development of persistent pain induced by tissue inflammation and nerve injury. However, the role of glial cells in bone cancer pain is not well understood. The present study evaluated the spinal glial activation in a novel rat model of bone cancer pain produced by injecting AT-3.1 prostate cancer cells into the unilateral tibia of male Copenhagen rats. The structural damage to the tibia was monitored by radiological analysis. The thermal hyperalgesia, mechanical hyperalgesia and allodynia, and spontaneous flinch were measured. The results showed that: (1) inoculation of prostate cancer cells, but not the vehicle Hank's solution, induced progressive bone destruction at the proximal epiphysis of the tibia from day 7-20 post inoculation; (2) the inoculation also induced progressive thermal hyperalgesia, mechanical hyperalgesia, mechanical allodynia, and spontaneous flinches; (3) astrocytes and microglia were significantly activated in the spinal cord ipsilateral to the cancer leg, characterized by enhanced immunostaining of both glial fibrillary acidic protein (GFAP, astrocyte marker) and OX-42 (microglial marker); (4) IL-1beta was up-regulated in the ipsilateral spinal cord, evidenced by an increase of IL-1beta immunostained astrocytes. These results demonstrate that injection of AT-3.1 prostate cancer cells into the tibia produces progressive hyperalgesia and allodynia associated with the progression of tibia destruction, indicating the successful establishment of a novel male rat model of bone cancer pain. Further, bone cancer activates spinal glial cells, which may release IL-1beta and other cytokines and contribute to hyperalgesia.
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Affiliation(s)
- Rui-Xin Zhang
- Center For Integrative Medicine, School of Medicine, University of Maryland, 3rd Floor, James Kernan Hospital Mansion, 2200 Kernan Drive, Baltimore, MD 21207, USA.
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Hubbard RD, Winkelstein BA. Transient cervical nerve root compression in the rat induces bilateral forepaw allodynia and spinal glial activation: mechanical factors in painful neck injuries. Spine (Phila Pa 1976) 2005; 30:1924-32. [PMID: 16135981 DOI: 10.1097/01.brs.0000176239.72928.00] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN An in vivo rat model of transient cervical nerve root compression. OBJECTIVES To investigate the potential for cervical nerve root compression to produce behavioral hypersensitivity and examine its dependence on compression. SUMMARY OF BACKGROUND DATA Clinically, nerve root injury has been hypothesized as a potential source of neck pain, particularly because cervical nerve roots are at mechanical risk for injury during neck loading. Lumbar radiculopathy models of nerve root ligation show that mechanical allodynia and spinal glial changes depend on nerve root deformation magnitude. However, no investigation has been performed to examine cervical nerve root compression as a cause of pain. METHODS Two compressive forces (10 and 60 grams force [gf]) were transiently applied to the C7 nerve roots unilaterally using microvascular clips in separate groups (n = 12 each). Sham procedures were also performed in a separate group of rats (n = 12). Bilateral forepaw mechanical allodynia was monitored after surgery for 7 days. On day 7, spinal glial activation was assessed using immunohistochemistry to investigate its dependence on nerve root compressive force, in the context of behavioral hypersensitivity. RESULTS Bilateral allodynia was observed following injury, which was significantly (P < 0.042) increased over sham and baseline responses. No difference in allodynia was found between the 10 and 60 gf injuries. Astrocytic and microglial activation were observed in the ipsilateral dorsal horn following compression, with only astrocytic activation paralleling allodynia patterns. CONCLUSIONS Results imply a force threshold exists less than 10 gf for persistent pain symptoms following transient cervical nerve root compression. Findings also suggest that spinal glial activation may be related to behavioral sensitivity and may modulate cervical nerve root mediated pain.
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Affiliation(s)
- Raymond D Hubbard
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104-6392, USA
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Massie JB, Huang B, Malkmus S, Yaksh TL, Kim CW, Garfin SR, Akeson WH. A preclinical post laminectomy rat model mimics the human post laminectomy syndrome. J Neurosci Methods 2004; 137:283-9. [PMID: 15262072 DOI: 10.1016/j.jneumeth.2004.02.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 02/26/2004] [Accepted: 02/26/2004] [Indexed: 11/16/2022]
Abstract
Chronic low back pain with sciatica complicating post laminectomy surgery is poorly understood. It is likely that some aspects of persistent pain of the syndrome results from spinal facilitation in which there is lowering of pain excitation levels. A small animal preclinical model is needed that mimics the clinical condition to permit detailed studies of the underlying altered neurochemistry of the sensory pathways. We propose herein a rat laminectomy model containing the elements required for study of the neurobiology of the condition. The model consists of a surgical laminectomy that includes L5 spinal nerve manipulation and disc injury, elements necessarily employed in human disc herniation surgery. At 8 weeks post laminectomy the proposed model demonstrates paraspinous muscle spasm, tail contracture, behavioral pain behavior, tactile allodynia, epidural and nerve root scarring, and nerve root adherence by scar to the underlying disc and adjacent pedicle. Two underlying pain facilitation states are invoked in the clinical condition: (1) an inflammatory state required to achieve wound healing; and (2) a nerve injury state resulting from nerve manipulation and subsequent epidural scarring, spinal nerve scarring, and spinal nerve tethering to the adjacent disc and pedicle. Both pain facilitation states are active in the model.
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Affiliation(s)
- Jennifer B Massie
- Department of Orthopaedics, Veterans Administration San Diego Health Care System and University of California, 3350 La Jolla Village Drive, San Diego, CA 92161, USA
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Randy Jinkins J. The anatomic and physiologic basis of local, referred and radiating lumbosacral pain syndromes related to disease of the spine. J Neuroradiol 2004; 31:163-80. [PMID: 15356442 DOI: 10.1016/s0150-9861(04)96988-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Conscious perception and unconscious effects originating from the vertebral column and its neural structures, although complex, have definite pathways represented in a network of peripheral and central nervous system (CNS) ramifications. These neural relationships consequently result in superimposed focal and diffuse, local and remote conscious perceptions and unconscious effects. Any one or combination of somatic and autonomic signs and symptoms may potentially be observed in a particular patient. This variety and inconsistency may mislead or confuse both the patient and the physician. A clear understanding of the basic anatomic and physiologic concepts underlying this complexity should accompany clinical considerations of the potential significance of spondylogenic and neurogenic syndromes in any disease process affecting the spine.
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Affiliation(s)
- J Randy Jinkins
- Department of Radiology, Downstate Medical Center, State University of New York, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
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Sekiguchi Y, Kikuchi S, Myers RR, Campana WM. ISSLS prize winner: Erythropoietin inhibits spinal neuronal apoptosis and pain following nerve root crush. Spine (Phila Pa 1976) 2003; 28:2577-84. [PMID: 14652474 DOI: 10.1097/01.brs.0000096674.12519.12] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN The authors investigated the association of L5 proximal nerve root injury with spinal cord neuronal apoptosis (histologic) and whether exogenous erythropoietin therapy might reduce apoptosis/or pain (behavioral). OBJECTIVES The first objective was to determine whether nerve root crush induces specific programmed cell death of spinal neurons in the dorsal and ventral horn and whether this is correlated with pain behaviors. The second objective was to determine if exogenous erythropoietin might reduce apoptosis and/or pain. SUMMARY OF BACKGROUND DATA Whether spinal neuronal apoptosis is correlated with pain behaviors following nerve root injury remains unknown. It has been hypothesized that neuroprotective factors may alleviate pain behaviors by protecting neurons from death. Erythropoietin is a hematopoietic growth factor that recently has been demonstrated as a potent neuroprotective factor against ischemic damage in the brain. The effects of erythropoietin on pain and spinal cord neurons have not been examined. METHODS Sprague-Dawley rats received a L5 proximal nerve root crush injury or sham operation and were separated into two treatment groups for subcutaneous injection: 1) vehicle; 2) recombinant human erythropoietin, 2680 U/kg. The rats were sacrificed, and spinal cords were removed for apoptotic and immunohistochemical analysis at 0, 1, and 3 days after surgery. To determine whether recombinant human erythropoietin prevented mechanical allodynia in animals with nerve root crushes (n = 12/group), both treatment groups were tested for pain behaviors using the von Frey test at -1, -2, -3, 1, 3, 7, 11, and 14 days after surgery. RESULTS After nerve root injury, apoptotic neurons increased by 80% in the ipsilateral spinal cord and moderately in contralateral spinal cord in vehicle-treated animals compared to uninjured controls. Recombinant human erythropoietin reduced (P < 0.05) neuronal apoptosis in both superficial dorsal and ventral horns of the spinal cord. This corresponded with identification of erythropoietin and its receptors on spinal neurons and reductions in TNF-alpha colocalization in ventral horn neurons. Mechanical allodynia developed in the corresponding ipsilateral hind paw within 1 day and was sustained until day 14. Recombinant human erythropoietin-treated animals demonstrated faster recovery from mechanical allodynia compared with vehicle-treated controls (P < 0.05). CONCLUSIONS Our findings indicated that L5 proximal nerve root crush increased neuronal apoptosis in the superficial dorsal and ventral horn that correlated with mechanical allodynia. Exogenous recombinant human erythropoietin facilitated receptor-mediated neuroprotection of spinal cord neurons and faster recovery from mechanical allodynia. Erythropoietin may be a potential therapeutic factor for patients with low back pain by providing pain relief and neuroprotection.
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Affiliation(s)
- Yasufumi Sekiguchi
- Department of Orthopaedic Surgery, Fukushima Medical University, Fukushima, Japan
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