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Lu J, Zhao XJ, Ruan Y, Liu XJ, Di X, Xu R, Wang JY, Qian MY, Jin HM, Li WJ, Shen X. Desloratadine ameliorates paclitaxel-induced peripheral neuropathy and hypersensitivity reactions in mice. Acta Pharmacol Sin 2024:10.1038/s41401-024-01301-z. [PMID: 38789495 DOI: 10.1038/s41401-024-01301-z] [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: 12/20/2023] [Accepted: 04/29/2024] [Indexed: 05/26/2024] Open
Abstract
Paclitaxel (PTX) serves as a primary chemotherapy agent against diverse solid tumors including breast cancer, lung cancer, head and neck cancer and ovarian cancer, having severe adverse effects including PTX-induced peripheral neuropathy (PIPN) and hypersensitivity reactions (HSR). A recommended anti-allergic agent diphenhydramine (DIP) has been used to alleviate PTX-induced HSR. Desloratadine (DLT) is a third generation of histamine H1 receptor antagonist, but also acted as a selective antagonist of 5HTR2A. In this study we investigated whether DLT ameliorated PIPN-like symptoms in mice and the underlying mechanisms. PIPN was induced in male mice by injection of PTX (4 mg/kg, i.p.) every other day for 4 times. The mice exhibited 50% reduction in mechanical threshold, paw thermal response latency and paw cold response latency compared with control mice. PIPN mice were treated with DLT (10, 20 mg/kg, i.p.) 30 min before each PTX administration in the phase of establishing PIPN mice model and then administered daily for 4 weeks after the model was established. We showed that DLT administration dose-dependently elevated the mechanical, thermal and cold pain thresholds in PIPN mice, whereas administration of DIP (10 mg/kg, i.p.) had no ameliorative effects on PIPN-like symptoms. We found that the expression of 5HTR2A was selectively elevated in the activated spinal astrocytes of PIPN mice. Spinal cord-specific 5HTR2A knockdown by intrathecal injection of AAV9-5Htr2a-shRNA significantly alleviated the mechanical hyperalgesia, thermal and cold hypersensitivity in PIPN mice, while administration of DLT (20 mg/kg) did not further ameliorate PIPN-like symptoms. We demonstrated that DLT administration alleviated dorsal root ganglion neuronal damage and suppressed sciatic nerve destruction, spinal neuron apoptosis and neuroinflammation in the spinal cord of PIPN mice. Furthermore, we revealed that DLT administration suppressed astrocytic neuroinflammation via the 5HTR2A/c-Fos/NLRP3 pathway and blocked astrocyte-neuron crosstalk by targeting 5HTR2A. We conclude that spinal 5HTR2A inhibition holds promise as a therapeutic approach for PIPN and we emphasize the potential of DLT as a dual-functional agent in ameliorating PTX-induced both PIPN and HSR in chemotherapy. In summary, we determined that spinal 5HTR2A was selectively activated in PIPN mice and DLT could ameliorate the PTX-induced both PIPN- and HSR-like pathologies in mice. DLT alleviated the damages of DRG neurons and sciatic nerves, while restrained spinal neuronal apoptosis and CGRP release in PIPN mice. The underlying mechanisms were intensively investigated by assay against the PIPN mice with 5HTR2A-specific knockdown in the spinal cord by injection of adeno-associated virus 9 (AAV9)-5Htr2a-shRNA. DLT inhibited astrocytic NLRP3 inflammasome activation-mediated spinal neuronal damage through 5HTR2A/c-FOS pathway. Our findings have supported that spinal 5HTR2A inhibition shows promise as a therapeutic strategy for PIPN and highlighted the potential advantage of DLT as a dual-functional agent in preventing against PTX-induced both PIPN and HSR effects in anticancer chemotherapy.
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Affiliation(s)
- Jian Lu
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xue-Jian Zhao
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Yuan Ruan
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xiao-Jing Liu
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xuan Di
- School of Pharmacy, Experiment Center for Science and Technology, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Rui Xu
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Jia-Ying Wang
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Min-Yi Qian
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Hong-Ming Jin
- School of Pharmacy, Experiment Center for Science and Technology, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Wen-Jun Li
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
| | - Xu Shen
- School of Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
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Cohen SP, Caterina MJ, Yang SY, Socolovsky M, Sommer C. Pain in the Context of Sensory Deafferentation. Anesthesiology 2024; 140:824-848. [PMID: 38470115 DOI: 10.1097/aln.0000000000004881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Pain that accompanies deafferentation is one of the most mysterious and misunderstood medical conditions. Prevalence rates for the assorted conditions vary considerably but the most reliable estimates are greater than 50% for strokes involving the somatosensory system, brachial plexus avulsions, spinal cord injury, and limb amputation, with controversy surrounding the mechanistic contributions of deafferentation to ensuing neuropathic pain syndromes. Deafferentation pain has also been described for loss of other body parts (e.g., eyes and breasts) and may contribute to between 10% and upwards of 30% of neuropathic symptoms in peripheral neuropathies. There is no pathognomonic test or sign to identify deafferentation pain, and part of the controversy surrounding it stems from the prodigious challenges in differentiating cause and effect. For example, it is unknown whether cortical reorganization causes pain or is a byproduct of pathoanatomical changes accompanying injury, including pain. Similarly, ascertaining whether deafferentation contributes to neuropathic pain, or whether concomitant injury to nerve fibers transmitting pain and touch sensation leads to a deafferentation-like phenotype can be clinically difficult, although a detailed neurologic examination, functional imaging, and psychophysical tests may provide clues. Due in part to the concurrent morbidities, the physical, psychologic, and by extension socioeconomic costs of disorders associated with deafferentation are higher than for other chronic pain conditions. Treatment is symptom-based, with evidence supporting first-line antineuropathic medications such as gabapentinoids and antidepressants. Studies examining noninvasive neuromodulation and virtual reality have yielded mixed results.
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Affiliation(s)
- Steven P Cohen
- Departments of Anesthesiology, Neurology, Physical Medicine and Rehabilitation, Psychiatry and Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois; Departments of Physical Medicine and Rehabilitation and Anesthesiology, Walter Reed National Military Medical Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Michael J Caterina
- Neurosurgery Pain Research Institute and Department of Biological Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Su-Yin Yang
- Psychology Service, Woodlands Health, and Adjunct Faculty, Lee Kong Chian School of Medicine, Singapore
| | - Mariano Socolovsky
- Department of Neurosurgery, University of Buenos Aires, Buenos Aires, Argentina
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Ohashi N, Uta D, Ohashi M, Hoshino R, Baba H. Omega-conotoxin MVIIA reduces neuropathic pain after spinal cord injury by inhibiting N-type voltage-dependent calcium channels on spinal dorsal horn. Front Neurosci 2024; 18:1366829. [PMID: 38469570 PMCID: PMC10925679 DOI: 10.3389/fnins.2024.1366829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 02/15/2024] [Indexed: 03/13/2024] Open
Abstract
Spinal cord injury (SCI) leads to the development of neuropathic pain. Although a multitude of pathological processes contribute to SCI-induced pain, excessive intracellular calcium accumulation and voltage-gated calcium-channel upregulation play critical roles in SCI-induced pain. However, the role of calcium-channel blockers in SCI-induced pain is unknown. Omega-conotoxin MVIIA (MVIIA) is a calcium-channel blocker that selectively inhibits N-type voltage-dependent calcium channels and demonstrates neuroprotective effects. Therefore, we investigated spinal analgesic actions and cellular mechanisms underlying the analgesic effects of MVIIA in SCI. We used SCI-induced pain model rats and conducted behavioral tests, immunohistochemical analyses, and electrophysiological experiments (in vitro whole-cell patch-clamp recording and in vivo extracellular recording). A behavior study suggested intrathecal MVIIA administration in the acute phase after SCI induced analgesia for mechanical allodynia. Immunohistochemical experiments and in vivo extracellular recordings suggested that MVIIA induces analgesia in SCI-induced pain by directly inhibiting neuronal activity in the superficial spinal dorsal horn. In vitro whole-cell patch-clamp recording showed that MVIIA inhibits presynaptic N-type voltage-dependent calcium channels expressed on primary afferent Aδ-and C-fiber terminals and suppresses the presynaptic glutamate release from substantia gelatinosa in the spinal dorsal horn. In conclusion, MVIIA administration in the acute phase after SCI may induce analgesia in SCI-induced pain by inhibiting N-type voltage-dependent calcium channels on Aδ-and C-fiber terminals in the spinal dorsal horn, resulting in decreased neuronal excitability enhanced by SCI-induced pain.
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Affiliation(s)
- Nobuko Ohashi
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Masayuki Ohashi
- Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Rintaro Hoshino
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Baba
- Division of Anesthesiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Rosner J, de Andrade DC, Davis KD, Gustin SM, Kramer JLK, Seal RP, Finnerup NB. Central neuropathic pain. Nat Rev Dis Primers 2023; 9:73. [PMID: 38129427 PMCID: PMC11329872 DOI: 10.1038/s41572-023-00484-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/21/2023] [Indexed: 12/23/2023]
Abstract
Central neuropathic pain arises from a lesion or disease of the central somatosensory nervous system such as brain injury, spinal cord injury, stroke, multiple sclerosis or related neuroinflammatory conditions. The incidence of central neuropathic pain differs based on its underlying cause. Individuals with spinal cord injury are at the highest risk; however, central post-stroke pain is the most prevalent form of central neuropathic pain worldwide. The mechanisms that underlie central neuropathic pain are not fully understood, but the pathophysiology likely involves intricate interactions and maladaptive plasticity within spinal circuits and brain circuits associated with nociception and antinociception coupled with neuronal hyperexcitability. Modulation of neuronal activity, neuron-glia and neuro-immune interactions and targeting pain-related alterations in brain connectivity, represent potential therapeutic approaches. Current evidence-based pharmacological treatments include antidepressants and gabapentinoids as first-line options. Non-pharmacological pain management options include self-management strategies, exercise and neuromodulation. A comprehensive pain history and clinical examination form the foundation of central neuropathic pain classification, identification of potential risk factors and stratification of patients for clinical trials. Advanced neurophysiological and neuroimaging techniques hold promise to improve the understanding of mechanisms that underlie central neuropathic pain and as predictive biomarkers of treatment outcome.
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Affiliation(s)
- Jan Rosner
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Department of Neurology, University Hospital Bern, Inselspital, University of Bern, Bern, Switzerland
| | - Daniel C de Andrade
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
| | - Karen D Davis
- Division of Brain, Imaging and Behaviour, Krembil Brain Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
- Department of Surgery and Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Sylvia M Gustin
- Centre for Pain IMPACT, Neuroscience Research Australia, Sydney, New South Wales, Australia
- NeuroRecovery Research Hub, School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - John L K Kramer
- International Collaboration on Repair Discoveries, ICORD, University of British Columbia, Vancouver, Canada
- Department of Anaesthesiology, Pharmacology & Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Rebecca P Seal
- Pittsburgh Center for Pain Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Departments of Neurobiology and Otolaryngology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nanna B Finnerup
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark.
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Lee JY, Park CS, Seo KJ, Kim IY, Han S, Youn I, Yune TY. IL-6/JAK2/STAT3 axis mediates neuropathic pain by regulating astrocyte and microglia activation after spinal cord injury. Exp Neurol 2023; 370:114576. [PMID: 37863306 DOI: 10.1016/j.expneurol.2023.114576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/02/2023] [Accepted: 10/16/2023] [Indexed: 10/22/2023]
Abstract
After spinal cord injury (SCI), the control of activated glial cells such as microglia and astrocytes has emerged as a promising strategy for neuropathic pain management. However, signaling mechanism involved in glial activation in the process of neuropathic pain development and maintenance after SCI is not well elucidated. In this study, we investigated the potential role and mechanism of the JAK2/STAT3 pathway associated with glial cell activation in chronic neuropathic pain development and maintenance after SCI. One month after contusive SCI, the activation of JAK2/STAT3 pathway was markedly upregulated in both microglia and astrocyte in nociceptive processing regions of the lumbar spinal cord. In addition, both mechanical allodynia and thermal hyperalgesia was significantly inhibited by a JAK2 inhibitor, AG490. In particular, AG490 treatment inhibited both microglial and astrocyte activation in the lumbar (L) 4-5 dorsal horn and significantly decreased levels of p-p38MAPK, p-ERK and p-JNK, which are known to be activated in microglia (p-p38MAPK and p-ERK) and astrocyte (p-JNK). Experiments using primary cell cultures also revealed that the JAK2/STAT3 pathway promoted microglia and astrocyte activation after lipopolysaccharide stimulation. Furthermore, JAK2/STAT3 signaling and pain behaviors were significantly attenuated when the rats were treated with anti-IL-6 antibody. Finally, minocycline, a tetracycline antibiotic, inhibited IL-6/JAK2/STAT3 signaling pathway in activated glial cells and restored nociceptive thresholds and the hyperresponsiveness of dorsal neurons. These results suggest an important role of the IL-6/JAK2/STAT3 pathway in the activation of microglia and astrocytes and in the maintenance of chronic below-level pain after SCI.
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Affiliation(s)
- Jee Youn Lee
- Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 02453, Republic of Korea
| | - Chan Sol Park
- Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 02453, Republic of Korea; Department of Biomedical Science, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Kyung Jin Seo
- Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 02453, Republic of Korea; Department of Biomedical Science, Kyung Hee University, Seoul 02447, Republic of Korea
| | - In Yi Kim
- Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 02453, Republic of Korea; Department of Biomedical Science, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Sungmin Han
- Biomedical Research Division, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Inchan Youn
- Biomedical Research Division, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Tae Young Yune
- Age-Related and Brain Diseases Research Center, School of Medicine, Kyung Hee University, Seoul 02453, Republic of Korea; Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul, 02453, Republic of Korea; Biomedical Science Institute, Kyung Hee University, Seoul 02447, Republic of Korea.
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Wu D, Wang P, Zhao C, Su J, Zhang J, Ma W, Zhang Y, Xu H. Levo-tetrahydropalmatine ameliorates neuropathic pain by inhibiting the activation of the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 121:155075. [PMID: 37741158 DOI: 10.1016/j.phymed.2023.155075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 08/27/2023] [Accepted: 09/09/2023] [Indexed: 09/25/2023]
Abstract
BACKGROUND Because of the complex pathogenesis of neuropathic pain (NP), the therapeutic efficacy of existing drugs is not satisfactory. Accumulating studies have indicated that neuroinflammation may play a key role in NP onset and progression. Levo-tetrahydropalmatine (l-THP) has been extensively used for relieving chronic pain for decades. However, its potential mechanisms against NP have not yet been fully elucidated. PURPOSE Exploring and elucidating the therapeutic effect and pharmacological mechanism of l-THP in treating NP. METHODS RNA-seq and bioinformatics analyses were carried out to identify effective target profiling of I-THP in chronic constrictive injury (CCI) rats. The I-THP related hub targets and signaling pathways were obtained via bioinformatics analysis, then subjected to in-depth analyses through experiments in vivo. A gain-of-function study further confirmed the role of Clec7a in l-THP-mediated pain relief. Finally, the interaction between l-THP and Clec7a was verified through molecular docking and surface plasmon resonance (SPR). RESULTS l-THP treatment effectively alleviated mechanical and thermal allodynia in NP model rats. Functionally, the I-THP effective targets were mainly enriched in inflammatory response-related pathways. Furthermore, Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis was selected as one of the potential pathways of l-THP against NP. Mechanically, l-THP markedly reduced CCI-induced Clec7a overexpression, significantly inhibited the Clec7a-triggered phosphorylation of MAPK and NF-κB-p65, and decreased the expression of pyroptosis-related protein NLRP3 and Caspase-1-p20. The analgesic effect of l-THP on NP was partly eliminated when transfecting the overexpression vector virus pLVSO5Clec7a. Importantly, molecular docking and SPR data revealed that l-THP directly binds with the Clec7a protein. CONCLUSION This study is the first to indicate that l-THP may exert an analgesic effect through inhibiting neuroinflammation via the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis, supporting the clinical utility of l-THP in NP therapy.
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Affiliation(s)
- Dan Wu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Ping Wang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Chunhui Zhao
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Jin Su
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Junhong Zhang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Wangming Ma
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China
| | - Yanqiong Zhang
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China.
| | - Haiyu Xu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, PR China.
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Ferreyra S, González S. Therapeutic potential of progesterone in spinal cord injury-induced neuropathic pain: At the crossroads between neuroinflammation and N-methyl-D-aspartate receptor. J Neuroendocrinol 2023; 35:e13181. [PMID: 35924434 DOI: 10.1111/jne.13181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/13/2022] [Accepted: 06/19/2022] [Indexed: 10/17/2022]
Abstract
In recent decades, an area of active research has supported the notion that progesterone promotes a wide range of remarkable protective actions in experimental models of nervous system trauma or disease, and has also provided a strong basis for considering this steroid as a promising molecule for modulating the complex maladaptive changes that lead to neuropathic pain, especially after spinal cord injury. In this review, we intend to give the readers a brief appraisal of the main mechanisms underlying the increased excitability of the spinal circuit in the pain pathway after trauma, with particular emphasis on those mediated by the activation of resident glial cells, the subsequent release of proinflammatory cytokines and their impact on N-methyl-D-aspartate receptor function. We then summarize the available preclinical data pointing to progesterone as a valuable repurposing molecule for blocking critical cellular and molecular events that occur in the dorsal horn of the injured spinal cord and are related to the development of chronic pain. Since the treatment and management of neuropathic pain after spinal injury remains challenging, the potential therapeutic value of progesterone opens new traslational perspectives to prevent central pain.
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Affiliation(s)
- Sol Ferreyra
- Instituto de Biología y Medicina Experimental, Laboratorio de Nocicepción y Dolor Neuropático, CONICET, Buenos Aires, Argentina
| | - Susana González
- Instituto de Biología y Medicina Experimental, Laboratorio de Nocicepción y Dolor Neuropático, CONICET, Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Medicina, Departamento de Bioquímica Humana, Buenos Aires, Argentina
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The Impact of Activity-Based Interventions on Neuropathic Pain in Experimental Spinal Cord Injury. Cells 2022; 11:cells11193087. [PMID: 36231048 PMCID: PMC9563089 DOI: 10.3390/cells11193087] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/17/2022] Open
Abstract
Physical activity-based rehabilitative interventions represent the main treatment concept for people suffering from spinal cord injury (SCI). The role such interventions play in the relief of neuropathic pain (NP) states is emerging, along with underlying mechanisms resulting in SCI-induced NP (SCI-NP). Animal models have been used to investigate the benefits of activity-based interventions (ABI), such as treadmill training, wheel running, walking, swimming, and bipedal standing. These activity-based paradigms have been shown to modulate inflammatory-related alterations as well as induce functional and structural changes in the spinal cord gray matter circuitry correlated with pain behaviors. Thus far, the research available provides an incomplete picture of the cellular and molecular pathways involved in this beneficial effect. Continued research is essential for understanding how such interventions benefit SCI patients suffering from NP and allow the development of individualized rehabilitative therapies. This article reviews preclinical studies on this specific topic, goes over mechanisms involved in SCI-NP in relation to ABI, and then discusses the effectiveness of different activity-based paradigms as they relate to different forms, intensity, initiation times, and duration of ABI. This article also summarizes the mechanisms of respective interventions to ameliorate NP after SCI and provides suggestions for future research directions.
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Defrin R, Gruener H, Gaidukov E, Bondi M, Rachamim-Katz O, Ringler E, Blumen N, Zeilig G. From acute to long-term alterations in pain processing and modulation after spinal cord injury: mechanisms related to chronification of central neuropathic pain. Pain 2022; 163:e94-e105. [PMID: 33863855 DOI: 10.1097/j.pain.0000000000002315] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/10/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT A severe and debilitating consequence of a spinal cord injury (SCI) is central neuropathic pain (CNP). Our aim was to investigate the processes leading to CNP emergence and chronification by analyzing causal relationship over time between spinothalamic function, pain excitability, and pain inhibition after SCI. This longitudinal follow-up study included 53 patients with acute SCI and 20 healthy controls. Spinothalamic, pain excitability, and intrasegmental and extrasegmental pain inhibition indices were repeatedly evaluated at 1.5, 3, and 6 months post-SCI. Between- and within-group analyses were conducted among those patients who eventually developed CNP and those who did not. Healthy controls were evaluated twice for repeatability analysis. Patients who developed CNP, compared with those who did not, exhibited increased thermal thresholds (P < 0.05), reduced pain adaptation (P < 0.01), and conditioned pain modulation (P < 0.05), early post-injury, and the CNP group's manifestations remained worse throughout the follow-up. By contrast, allodynia frequency was initially similar across SCI groups, but gradually increased in the subacute phase onward only among the CNP group (P < 0.001), along with CNP emergence. Early worse spinothalamic and pain inhibition preceded CNP and predicted its occurrence, and early worse pain inhibition mediated the link between spinothalamic function and CNP. Crossover associations were observed between early and late pain inhibition and excitability. Inefficient intrasegmental and extrasegmental inhibition, possibly resulting from spinothalamic deafferentation, seems to ignite CNP chronification. Pain excitability probably contributes to CNP maintenance, possibly via further exhaustion of the inhibitory control. Preemptive treatment promoting antinociception early post-SCI may mitigate or prevent CNP.
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Affiliation(s)
- Ruth Defrin
- Department of Physical Therapy at Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Hila Gruener
- Department of Physical Therapy at Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Evgeni Gaidukov
- Department of Neurological Rehabilitation, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
- Department of Rehabilitation Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Moshe Bondi
- Department of Neurological Rehabilitation, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
- Department of Rehabilitation Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Orna Rachamim-Katz
- Barzilai Day Care Rehabilitation Unit, Barzilai Medical Center, Ashkelon, Israel
| | - Erez Ringler
- Department of Neurological Rehabilitation, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
- Department of Rehabilitation Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nava Blumen
- Department of Neurological Rehabilitation, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
- Department of Rehabilitation Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Gabi Zeilig
- Department of Neurological Rehabilitation, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel
- Department of Rehabilitation Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Rosner J, Negraeff M, Bélanger LM, Tsang A, Ritchie L, Mac-Thiong JM, Christie S, Wilson JR, Dhall S, Charest-Morin R, Street J, Ailon T, Paquette S, Dea N, Fisher CG, Dvorak MF, Finnerup NB, Kwon BK, Kramer JLK. Characterization of Hyperacute Neuropathic Pain after Spinal Cord Injury: A Prospective Study. THE JOURNAL OF PAIN 2021; 23:89-97. [PMID: 34302956 DOI: 10.1016/j.jpain.2021.06.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 06/19/2021] [Accepted: 06/25/2021] [Indexed: 10/20/2022]
Abstract
There is currently a lack of information regarding neuropathic pain in the very early stages of spinal cord injury (SCI). In the present study, neuropathic pain was assessed using the Douleur Neuropathique 4 Questions (DN4) for the patient's worst pain within the first 5 days of injury (i.e., hyperacute) and on follow-up at 3, 6, and 12 months. Within the hyperacute time frame (i.e., 5 days), at- and below-level neuropathic pain were reported as the worst pain in 23% (n = 18) and 5% (n = 4) of individuals with SCI, respectively. Compared to the neuropathic pain observed in this hyperacute setting, late presenting neuropathic pain was characterized by more intense painful electrical and cold sensations, but less itching sensations. Phenotypic differences between acute and late neuropathic pain support the incorporation of timing into a mechanism-based classification of neuropathic pain after SCI. The diagnosis of acute neuropathic pain after SCI is challenged by the presence of nociceptive and neuropathic pains, with the former potentially masking the latter. This may lead to an underestimation of the incidence of neuropathic pain during the very early, hyperacute time points post-injury. TRIAL REGISTRATION: ClinicalTrials.gov (Identifier: NCT01279811) PERSPECTIVE: This article presents distinct pain phenotypes of hyperacute and late presenting neuropathic pain after spinal cord injury and highlights the challenges of pain assessments in the acute phase after injury. This information may be relevant to clinical trial design and broaden our understanding of neuropathic pain mechanisms after spinal cord injury.
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Affiliation(s)
- Jan Rosner
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Spinal Cord Injury Center, Balgrist University Hospital, University of Zurich, Zurich, Switzerland; Department of Neurology, University Hospital Bern, Inselspital, University of Bern, Bern, Switzerland
| | - Michael Negraeff
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Department of Anesthesiology, Pharmacology, and Therapeutics, Faculty of Medicine, University of British Columbia, British Columbia, Canada
| | - Lise M Bélanger
- Vancouver Spine Program, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Angela Tsang
- Vancouver Spine Program, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Leanna Ritchie
- Vancouver Spine Program, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Jean-Marc Mac-Thiong
- Hôpital du Sacré-Coeur de Montréal, Montréal, Quebec, Canada; Faculty of Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Sean Christie
- Division of Neurosurgery, Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Jefferson R Wilson
- Division of Neurosurgery, Department of Surgery, University of Toronto, St Michael's Hospital, Toronto, Ontario, Canada
| | - Sanjay Dhall
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Raphaële Charest-Morin
- Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - John Street
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Tamir Ailon
- Division of Neurosurgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott Paquette
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Division of Neurosurgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicolas Dea
- Division of Neurosurgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Charles G Fisher
- Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marcel F Dvorak
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nanna B Finnerup
- Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Brian K Kwon
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Vancouver Spine Surgery Institute, Department of Orthopaedics, University of British Columbia, Vancouver, British Columbia, Canada
| | - John L K Kramer
- International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada; Department of Anesthesiology, Pharmacology, and Therapeutics, Faculty of Medicine, University of British Columbia, British Columbia, Canada.
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11
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Kong F, Sun K, Zhu J, Li F, Lin F, Sun X, Luo X, Ren C, Lu L, Zhao S, Sun J, Wang Y, Shi J. PD-L1 Improves Motor Function and Alleviates Neuropathic Pain in Male Mice After Spinal Cord Injury by Inhibiting MAPK Pathway. Front Immunol 2021; 12:670646. [PMID: 33936116 PMCID: PMC8081847 DOI: 10.3389/fimmu.2021.670646] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/29/2021] [Indexed: 12/17/2022] Open
Abstract
Background Traumatic spinal cord injury (SCI) causes severe motor dysfunction and persistent central neuropathic pain (Nep), which has not yet been effectively cured. Programmed cell death ligand-1 (PD-L1) is typically produced by cancer cells and contributes to the immune-suppressive in tumor microenvironment. However, the role of PD-L1 in regulating inflammatory response and Nep after SCI remains unclear. A growing amount of researches have begun to investigate the effect of PD-L1 on macrophages and microglia in recent years. Considering the pivotal role of macrophages/microglia in the inflammatory response after SCI, we proposed the hypothesis that PD-L1 improved the recovery of locomotor and sensory functions after SCI through regulating macrophages and microglia. Methods The mice SCI model was established to determine the changes in expression patterns of PD-L1. Meanwhile, we constructed PD-L1 knockout mice to observe differences in functional recovery and phenotypes of macrophages/microglia post-SCI. Results In present study, PD-L1 was significantly upregulated after SCI and highly expressed on macrophages/microglia at the injury epicenter. PD-L1 knockout (KO) mice showed worse locomotor recovery and more serious pathological pain compared with wild-type (WT) mice. Furthermore, deletion of PD-L1 significantly increased the polarization of M1-like macrophages/microglia. Mechanistic analysis revealed that PD-L1 may improve functional outcomes following SCI by inhibiting phosphorylation of p38 and ERK1/2. Conclusions Our observations implicate the involvement of PD-L1 in recovery of SCI and provide a new treatment strategy for the prevention and treatment of this traumatic condition.
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Affiliation(s)
- Fanqi Kong
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Kaiqiang Sun
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Jian Zhu
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Fudong Li
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Feng Lin
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Xiaofei Sun
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Xi Luo
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Changzhen Ren
- Department of Cardiology, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Lantao Lu
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - ShuJie Zhao
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jingchuan Sun
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Yuan Wang
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
| | - Jiangang Shi
- Department of Orthopedic Surgery, Spine Center, Changzheng Hospital, Naval Medical University, Shanghai, China
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12
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Bannerman CA, Douchant K, Sheth PM, Ghasemlou N. The gut-brain axis and beyond: Microbiome control of spinal cord injury pain in humans and rodents. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2021; 9:100059. [PMID: 33426367 PMCID: PMC7779861 DOI: 10.1016/j.ynpai.2020.100059] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/26/2020] [Accepted: 12/10/2020] [Indexed: 12/17/2022]
Abstract
Spinal cord injury (SCI) is a devastating injury to the central nervous system in which 60 to 80% of patients experience chronic pain. Unfortunately, this pain is notoriously difficult to treat, with few effective options currently available. Patients are also commonly faced with various compounding injuries and medical challenges, often requiring frequent hospitalization and antibiotic treatment. Change in the gut microbiome from the "normal" state to one of imbalance, referred to as gut dysbiosis, has been found in both patients and rodent models following SCI. Similarities exist in the bacterial changes observed after SCI and other diseases with chronic pain as an outcome. These changes cause a shift in the regulation of inflammation, causing immune cell activation and secretion of inflammatory mediators that likely contribute to the generation/maintenance of SCI pain. Therefore, correcting gut dysbiosis may be used as a tool towards providing patients with effective pain management and improved quality of life.
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Affiliation(s)
- Courtney A. Bannerman
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Katya Douchant
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Gastrointestinal Disease Research Unit, Kingston Health Sciences Center, Kingston, Ontario, Canada
| | - Prameet M. Sheth
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Department of Pathology and Molecular Medicine, Queen’s University, Kingston, Ontario, Canada
- Division of Microbiology, Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Gastrointestinal Disease Research Unit, Kingston Health Sciences Center, Kingston, Ontario, Canada
| | - Nader Ghasemlou
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Department of Anesthesiology and Perioperative Medicine, Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Centre for Neuroscience Studies, Queen’s University, Kingston, Ontario, Canada
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13
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Vianna-Barbosa R, Bahia CP, Sanabio A, de Freitas GPA, Madeiro da Costa RF, Garcez PP, Miranda K, Lent R, Tovar-Moll F. Myelination of Callosal Axons Is Hampered by Early and Late Forelimb Amputation in Rats. Cereb Cortex Commun 2020; 2:tgaa090. [PMID: 34296146 PMCID: PMC8152840 DOI: 10.1093/texcom/tgaa090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 11/17/2020] [Accepted: 11/22/2020] [Indexed: 11/14/2022] Open
Abstract
Deafferentation is an important determinant of plastic changes in the CNS, which consists of a loss of inputs from the body periphery or from the CNS itself. Although cortical reorganization has been well documented, white matter plasticity was less explored. Our goal was to investigate microstructural interhemispheric connectivity changes in early and late amputated rats. For that purpose, we employed diffusion-weighted magnetic resonance imaging, as well as Western blotting, immunohistochemistry, and electron microscopy of sections of the white matter tracts to analyze the microstructural changes in the corticospinal tract and in the corpus callosum (CC) sector that contains somatosensory fibers integrating cortical areas representing the forelimbs and compare differences in rats undergoing forelimb amputation as neonates, with those amputated as adults. Results showed that early amputation induced decreased fractional anisotropy values and reduction of total myelin amount in the cerebral peduncle contralateral to the amputation. Both early and late forelimb amputations induced decreased myelination of callosal fibers. While early amputation affected myelination of thinner axons, late amputation disrupted axons of all calibers. Since the CC provides a modulation of inhibition and excitation between the hemispheres, we suggest that the demyelination observed among callosal fibers may misbalance this modulation.
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Affiliation(s)
- Rodrigo Vianna-Barbosa
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Carlomagno P Bahia
- Institute of Health Sciences, Federal University of Pará, Pará CEP 66035-160, Brazil
| | - Alexandre Sanabio
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Gabriella P A de Freitas
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | | | - Patricia P Garcez
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Kildare Miranda
- National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil
| | - Roberto Lent
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,D'Or Institute of Research and Education (IDOR), Rio de Janeiro, CEP 22281-100, Brazil
| | - Fernanda Tovar-Moll
- Post-Graduate Program in Morphological Sciences, Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,National Center of Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro CEP 21941-902, Brazil.,D'Or Institute of Research and Education (IDOR), Rio de Janeiro, CEP 22281-100, Brazil
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14
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Depolarization-Dependent C-Raf Signaling Promotes Hyperexcitability and Reduces Opioid Sensitivity of Isolated Nociceptors after Spinal Cord Injury. J Neurosci 2020; 40:6522-6535. [PMID: 32690613 DOI: 10.1523/jneurosci.0810-20.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/16/2020] [Accepted: 07/13/2020] [Indexed: 12/22/2022] Open
Abstract
Chronic pain caused by spinal cord injury (SCI) is notoriously resistant to treatment, particularly by opioids. After SCI, DRG neurons show hyperactivity and chronic depolarization of resting membrane potential (RMP) that is maintained by cAMP signaling through PKA and EPAC. Importantly, SCI also reduces the negative regulation by Gαi of adenylyl cyclase and its production of cAMP, independent of alterations in G protein-coupled receptors and/or G proteins. Opioid reduction of pain depends on coupling of opioid receptors to Gαi/o family members. Combining high-content imaging and cluster analysis, we show that in male rats SCI decreases opioid responsiveness in vitro within a specific subset of small-diameter nociceptors that bind isolectin B4. This SCI effect is mimicked in nociceptors from naive animals by a modest 5 min depolarization of RMP (15 mm K+; -45 mV), reducing inhibition of cAMP signaling by μ-opioid receptor agonists DAMGO and morphine. Disinhibition and activation of C-Raf by depolarization-dependent phosphorylation are central to these effects. Expression of an activated C-Raf reduces sensitivity of adenylyl cyclase to opioids in nonexcitable HEK293 cells, whereas inhibition of C-Raf or treatment with the hyperpolarizing drug retigabine restores opioid responsiveness and blocks spontaneous activity of nociceptors after SCI. Inhibition of ERK downstream of C-Raf also blocks SCI-induced hyperexcitability and depolarization, without direct effects on opioid responsiveness. Thus, depolarization-dependent C-Raf and downstream ERK activity maintain a depolarized RMP and nociceptor hyperactivity after SCI, providing a self-reinforcing mechanism to persistently promote nociceptor hyperexcitability and limit the therapeutic effectiveness of opioids.SIGNIFICANCE STATEMENT Chronic pain induced by spinal cord injury (SCI) is often permanent and debilitating, and usually refractory to treatment with analgesics, including opioids. SCI-induced pain in a rat model has been shown to depend on persistent hyperactivity in primary nociceptors (injury-detecting sensory neurons), associated with a decrease in the sensitivity of adenylyl cyclase production of cAMP to inhibitory Gαi proteins in DRGs. This study shows that SCI and one consequence of SCI (chronic depolarization of resting membrane potential) decrease sensitivity to opioid-mediated inhibition of cAMP and promote hyperactivity of nociceptors by enhancing C-Raf activity. ERK activation downstream of C-Raf is necessary for maintaining ongoing depolarization and hyperactivity, demonstrating an unexpected positive feedback loop to persistently promote pain.
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15
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Skoog B, Jakobsson KE. Prevalence of Spasticity and Below-Level Neuropathic Pain Related to Spinal Cord Injury Level and Damage to the Lower Spinal Segments. ACTA ACUST UNITED AC 2020; 3:1000039. [PMID: 33884141 PMCID: PMC8008733 DOI: 10.2340/20030711-1000039] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2020] [Indexed: 11/16/2022]
Abstract
Objective To evaluate spasticity and below-level spinal cord injury neuropathic pain after spinal cord injury in patients with, or without, damage to the lumbar spinal cord and roots. Design/patients Chart review of 269 patients with spinal cord injury from segments C1 to T11. Methods Patients were interviewed concerning leg spasticity and below-level spinal cord injury neuropathic pain in the lower trunk and legs. Damage to the lumbar spinal cord and roots was inferred where there was radiological evidence of a vertebral fracture, spinal stenosis or the narrowing of spinal foramina of a vertebra from thoracic 11 to lumbar 5, or; magnetic resonance imaging showing evidence of damage to the lumbar spinal cord and roots. Results Among 161 patients without damage to the lumbar spinal cord and roots, 87% of those with cervical spinal cord injury experienced spasticity, compared with 85% with thoracic spinal cord injury. The corresponding figures for patients in whom damage to the lumbar spinal cord and roots was present were 57% and 52%, respectively. Below-level spinal cord injury neuropathic pain was not associated with damage to the lumbar spinal cord and roots. In those patients with no damage to the lumbar spinal cord and roots, regression showed that neither outcome was significantly associated with the level of spinal cord injury. Conclusion The lack of segmental dependency for spinal cord injury and spasticity suggests mechanisms restricted mainly to the lumbar spinal cord. For below-level spinal cord injury neuropathic pain, additional mechanisms, other than lesions of the spino-thalamic tract, must be considered.
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Affiliation(s)
- Bengt Skoog
- Department of Rehabilitation Medicine, Sahlgrenska University Hospital, and Sahlgrenska Academy, Institute of Neuroscience and Physiology, Section of Clinical Neuroscience and Rehabilitation, University of Gothenburg, Gothenburg, Sweden
| | - Karl-Erik Jakobsson
- Department of Rehabilitation Medicine, Sahlgrenska University Hospital, and Sahlgrenska Academy, Institute of Neuroscience and Physiology, Section of Clinical Neuroscience and Rehabilitation, University of Gothenburg, Gothenburg, Sweden
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