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Xu Q, Zheng Q, Cui X, Cleland A, Hincapie J, Raja SN, Dong X, Guan Y. Visualizing the modulation of neurokinin 1 receptor-positive neurons in the superficial dorsal horn by spinal cord stimulation in vivo. Pain 2024:00006396-990000000-00683. [PMID: 39140483 DOI: 10.1097/j.pain.0000000000003361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 06/25/2024] [Indexed: 08/15/2024]
Abstract
ABSTRACT Spinal cord stimulation (SCS) is an effective modality for pain treatment, yet its underlying mechanisms remain elusive. Neurokinin 1 receptor-positive (NK1R+) neurons in spinal lamina I play a pivotal role in pain transmission. To enhance our mechanistic understanding of SCS-induced analgesia, we investigated how different SCS paradigms modulate the activation of NK1R+ neurons, by developing NK1R-Cre;GCaMP6s transgenic mice and using in vivo calcium imaging of superficial NK1R+ neurons under anesthesia (1.5% isoflurane). Neurokinin 1 receptor-positive neurons in the lumbar spinal cord (L4-5) showed a greater activation by electrical test stimulation (TS, 3.0 mA, 1 Hz) at the hindpaw at 2 weeks after tibia-sparing nerve injury (SNI-t) than in naïve mice. Spinal cord stimulation was then delivered through a bipolar plate electrode placed epidurally at L1-2 level. The short-term 50-Hz high-intensity SCS (80% motor threshold [MoT], 10 minutes) induced robust and prolonged inhibition of NK1R+ neuronal responses to TS in both naïve and SNI-t mice. The 30-minute 50-Hz and 900-Hz SCS applied at moderate intensity (50% MoT) also significantly inhibited neuronal responses in SNI-t mice. However, at low intensity (20% MoT), the 30-minute 900-Hz SCS only induced persistent neuronal inhibition in naïve mice, but not in SNI-t mice. In conclusion, both 10-minute high-intensity SCS and 30-minute SCS at moderate intensity inhibit the activation of superficial NK1R+ neurons, potentially attenuating spinal nociceptive transmission. Furthermore, in vivo calcium imaging of NK1R+ neurons provides a new approach for exploring the spinal neuronal mechanisms of pain inhibition by neuromodulation pain therapies.
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Affiliation(s)
- Qian Xu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Qin Zheng
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Xiang Cui
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | | | | | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Department of Neurological Surgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Department of Neurological Surgery, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
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2
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Qiu H, Miraucourt LS, Petitjean H, Xu M, Theriault C, Davidova A, Soubeyre V, Poulen G, Lonjon N, Vachiery-Lahaye F, Bauchet L, Levesque-Damphousse P, Estall JL, Bourinet E, Sharif-Naeini R. Parvalbumin gates chronic pain through the modulation of firing patterns in inhibitory neurons. Proc Natl Acad Sci U S A 2024; 121:e2403777121. [PMID: 38916998 PMCID: PMC11228497 DOI: 10.1073/pnas.2403777121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 05/14/2024] [Indexed: 06/27/2024] Open
Abstract
Spinal cord dorsal horn inhibition is critical to the processing of sensory inputs, and its impairment leads to mechanical allodynia. How this decreased inhibition occurs and whether its restoration alleviates allodynic pain are poorly understood. Here, we show that a critical step in the loss of inhibitory tone is the change in the firing pattern of inhibitory parvalbumin (PV)-expressing neurons (PVNs). Our results show that PV, a calcium-binding protein, controls the firing activity of PVNs by enabling them to sustain high-frequency tonic firing patterns. Upon nerve injury, PVNs transition to adaptive firing and decrease their PV expression. Interestingly, decreased PV is necessary and sufficient for the development of mechanical allodynia and the transition of PVNs to adaptive firing. This transition of the firing pattern is due to the recruitment of calcium-activated potassium (SK) channels, and blocking them during chronic pain restores normal tonic firing and alleviates chronic pain. Our findings indicate that PV is essential for controlling the firing pattern of PVNs and for preventing allodynia. Developing approaches to manipulate these mechanisms may lead to different strategies for chronic pain relief.
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Affiliation(s)
- Haoyi Qiu
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Loïs S. Miraucourt
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Hugues Petitjean
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Mengyi Xu
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Catherine Theriault
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Albena Davidova
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
| | - Vanessa Soubeyre
- Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier34000, France
| | - Gaetan Poulen
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier34295, France
| | - Nicolas Lonjon
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier34295, France
| | - Florence Vachiery-Lahaye
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier34295, France
| | - Luc Bauchet
- Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier34000, France
- Department of Neurosurgery, Gui de Chauliac Hospital, and Donation and Transplantation Coordination Unit, Montpellier University Medical Center, Montpellier34295, France
| | | | - Jennifer L. Estall
- Institut de Recherches Cliniques de Montréal, Montreal, QCH2W 1R7, Canada
| | - Emmanuel Bourinet
- Institute of Functional Genomics, Montpellier University, CNRS, INSERM, Montpellier34000, France
| | - Reza Sharif-Naeini
- Department of Physiology, McGill University, Montreal, QCH3G 1Y6, Canada
- Alan Edwards Center for Research on Pain, McGill University, Montreal, QCH3A 2B4, Canada
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Hodkinson DJ, Drabek MM, Jung J, Lankappa ST, Auer DP. Theta Burst Stimulation of the Human Motor Cortex Modulates Secondary Hyperalgesia to Punctate Mechanical Stimuli. Neuromodulation 2024; 27:812-823. [PMID: 37952136 DOI: 10.1016/j.neurom.2023.10.007] [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: 07/12/2023] [Revised: 09/19/2023] [Accepted: 10/03/2023] [Indexed: 11/14/2023]
Abstract
OBJECTIVES Many chronic pain conditions show evidence of dysregulated synaptic plasticity, including the development and maintenance of central sensitization. This provides a strong rationale for neuromodulation therapies for the relief of chronic pain. However, variability in responses and low fidelity across studies remain an issue for both clinical trials and pain management, demonstrating insufficient mechanistic understanding of effective treatment protocols. MATERIALS AND METHODS In a randomized counterbalanced crossover designed study, we evaluated two forms of patterned repetitive transcranial magnetic stimulation, known as continuous theta burst stimulation (TBS) and intermittent TBS, during normal and central sensitization states. Secondary hyperalgesia (a form of use-dependent central sensitization) was induced using a well-established injury-free pain model and assessed by standardized quantitative sensory testing involving light touch and pinprick pain thresholds in addition to stimulus-response functions. RESULTS We found that continuous TBS of the human motor cortex has a facilitatory (pronociceptive) effect on the magnitude of perceived pain to secondary hyperalgesia, which may rely on induction and expression of neural plasticity through heterosynaptic long-term potentiation-like mechanisms. CONCLUSIONS By defining the underlying mechanisms of TBS-driven synaptic plasticity in the nociceptive system, we offer new insight into disease mechanisms and provide targets for promoting functional recovery and repair in chronic pain. For clinical applications, this knowledge is critical for development of more efficacious and mechanisms-based neuromodulation protocols, which are urgently needed to address the chronic pain and opioid epidemics.
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Affiliation(s)
- Duncan J Hodkinson
- Division of Mental Health and Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK; Sir Peter Mansfield Imaging Center, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health Research, Nottingham Biomedical Research Center, Queens Medical Center, Nottingham, UK.
| | - Marianne M Drabek
- Division of Mental Health and Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK; Sir Peter Mansfield Imaging Center, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health Research, Nottingham Biomedical Research Center, Queens Medical Center, Nottingham, UK
| | - JeYoung Jung
- School of Psychology, University of Nottingham, Nottingham, UK
| | - Sudheer T Lankappa
- Nottinghamshire Healthcare National Health Service Foundation Trust, Nottingham, UK
| | - Dorothee P Auer
- Division of Mental Health and Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, UK; Sir Peter Mansfield Imaging Center, School of Medicine, University of Nottingham, Nottingham, UK; National Institute for Health Research, Nottingham Biomedical Research Center, Queens Medical Center, Nottingham, UK
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Ginsberg AG, Lempka SF, Duan B, Booth V, Crodelle J. Mechanisms for dysregulation of excitatory-inhibitory balance underlying allodynia in dorsal horn neural subcircuits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598179. [PMID: 38915505 PMCID: PMC11195069 DOI: 10.1101/2024.06.10.598179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Chronic pain is a wide-spread condition that is debilitating and expensive to manage, costing the United States alone around $600 billion in 2010. In a common type of chronic pain called allodynia, non-painful stimuli produce painful responses with highly variable presentations across individuals. While the specific mechanisms remain unclear, allodynia is hypothesized to be caused by the dysregulation of excitatory-inhibitory (E-I) balance in pain-processing neural circuitry in the dorsal horn of the spinal cord. In this work, we analyze biophysically-motivated subcircuit structures that represent common motifs in neural circuits in layers I-II of the dorsal horn. These circuits are hypothesized to be part of the neural pathways that mediate two different types of allodynia: static and dynamic. We use neural firing rate models to describe the activity of populations of excitatory and inhibitory interneurons within each subcircuit. By accounting for experimentally-observed responses under healthy conditions, we specify model parameters defining populations of subcircuits that yield typical behavior under normal conditions. Then, we implement a sensitivity analysis approach to identify the mechanisms most likely to cause allodynia-producing dysregulation of the subcircuit's E-I signaling. We find that disruption of E-I balance generally occurs either due to downregulation of inhibitory signaling so that excitatory neurons are "released" from inhibitory control, or due to upregulation of excitatory neuron responses so that excitatory neurons "escape" their inhibitory control. Which of these mechanisms is most likely to occur, the subcircuit components involved in the mechanism, and the proportion of subcircuits exhibiting the mechanism can vary depending on the subcircuit structure. These results suggest specific hypotheses about diverse mechanisms that may be most likely responsible for allodynia, thus offering predictions for the high interindividual variability observed in allodynia and identifying targets for further experimental studies on the underlying mechanisms of this chronic pain condition.
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Affiliation(s)
- Alexander G. Ginsberg
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan, United States
| | - Scott F. Lempka
- Department of Biomedical Engineering, and Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, United States
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Bo Duan
- Department of Molecular, Cellular, & Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States
| | - Victoria Booth
- Department of Mathematics, University of Michigan, Ann Arbor, Michigan, United States
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Jennifer Crodelle
- Department of Mathematics and Statistics, Middlebury College, Middlebury, Vermont, United States
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5
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Mardell LC, Spedden ME, O'Neill GC, Tierney TM, Timms RC, Zich C, Barnes GR, Bestmann S. Concurrent spinal and brain imaging with optically pumped magnetometers. J Neurosci Methods 2024; 406:110131. [PMID: 38583588 DOI: 10.1016/j.jneumeth.2024.110131] [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: 08/18/2023] [Revised: 03/11/2024] [Accepted: 04/03/2024] [Indexed: 04/09/2024]
Abstract
BACKGROUND The spinal cord and its interactions with the brain are fundamental for movement control and somatosensation. However, brain and spinal electrophysiology in humans have largely been treated as distinct enterprises, in part due to the relative inaccessibility of the spinal cord. Consequently, there is a dearth of knowledge on human spinal electrophysiology, including the multiple pathologies that affect the spinal cord as well as the brain. NEW METHOD Here we exploit recent advances in the development of wearable optically pumped magnetometers (OPMs) which can be flexibly arranged to provide coverage of both the spinal cord and the brain in relatively unconstrained environments. This system for magnetospinoencephalography (MSEG) measures both spinal and cortical signals simultaneously by employing custom-made scanning casts. RESULTS We evidence the utility of such a system by recording spinal and cortical evoked responses to median nerve stimulation at the wrist. MSEG revealed early (10 - 15 ms) and late (>20 ms) responses at the spinal cord, in addition to typical cortical evoked responses (i.e., N20). COMPARISON WITH EXISTING METHODS Early spinal evoked responses detected were in line with conventional somatosensory evoked potential recordings. CONCLUSION This MSEG system demonstrates the novel ability for concurrent non-invasive millisecond imaging of brain and spinal cord.
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Affiliation(s)
- Lydia C Mardell
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK.
| | - Meaghan E Spedden
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - George C O'Neill
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Tim M Tierney
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Ryan C Timms
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Catharina Zich
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK
| | - Gareth R Barnes
- Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
| | - Sven Bestmann
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG, UK; Wellcome Centre for Human Neuroimaging, Department of Imaging Neuroscience, UCL Queen Square Institute of Neurology, University College London, WC1N 3AR, UK
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6
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Smith PA. BDNF in Neuropathic Pain; the Culprit that Cannot be Apprehended. Neuroscience 2024; 543:49-64. [PMID: 38417539 DOI: 10.1016/j.neuroscience.2024.02.020] [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: 12/16/2023] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
In males but not in females, brain derived neurotrophic factor (BDNF) plays an obligatory role in the onset and maintenance of neuropathic pain. Afferent terminals of injured peripheral nerves release colony stimulating factor (CSF-1) and other mediators into the dorsal horn. These transform the phenotype of dorsal horn microglia such that they express P2X4 purinoceptors. Activation of these receptors by neuron-derived ATP promotes BDNF release. This microglial-derived BDNF increases synaptic activation of excitatory dorsal horn neurons and decreases that of inhibitory neurons. It also alters the neuronal chloride gradient such the normal inhibitory effect of GABA is converted to excitation. By as yet undefined processes, this attenuated inhibition increases NMDA receptor function. BDNF also promotes the release of pro-inflammatory cytokines from astrocytes. All of these actions culminate in the increase dorsal horn excitability that underlies many forms of neuropathic pain. Peripheral nerve injury also alters excitability of structures in the thalamus, cortex and mesolimbic system that are responsible for pain perception and for the generation of co-morbidities such as anxiety and depression. The weight of evidence from male rodents suggests that this preferential modulation of excitably of supra-spinal pain processing structures also involves the action of microglial-derived BDNF. Possible mechanisms promoting the preferential release of BDNF in pain signaling structures are discussed. In females, invading T-lymphocytes increase dorsal horn excitability but it remains to be determined whether similar processes operate in supra-spinal structures. Despite its ubiquitous role in pain aetiology neither BDNF nor TrkB receptors represent potential therapeutic targets.
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Affiliation(s)
- Peter A Smith
- Neuroscience and Mental Health Institute and Department of Pharmacology, University of Alberta, Edmonton, Canada.
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7
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Lima Pessôa B, Hauwanga WN, Thomas A, Valentim G, McBenedict B. A Comprehensive Narrative Review of Neuropathic Pain: From Pathophysiology to Surgical Treatment. Cureus 2024; 16:e58025. [PMID: 38738050 PMCID: PMC11087935 DOI: 10.7759/cureus.58025] [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: 03/30/2024] [Accepted: 04/10/2024] [Indexed: 05/14/2024] Open
Abstract
Neuropathic pain is a challenging condition. Despite the immense progress made in the pathophysiology and treatment of such conditions, so much work still has to be done. New frontiers previously unexplored are now objects of study with exciting results, mainly regarding neuromodulation and optogenetics. This review explores the already known pathophysiology and the clinical and surgical treatment in the light of evidence-based medicine. Additionally, new concepts and insights are discussed, presenting the hope for the development of new paradigms in the treatment of neuropathic pain.
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Affiliation(s)
| | - Wilhelmina N Hauwanga
- Family Medicine, Faculty of Medicine, Federal University of the State of Rio de Janeiro, Rio de Janeiro, BRA
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8
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Abd-Elsayed A, Vardhan S, Aggarwal A, Vardhan M, Diwan SA. Mechanisms of Action of Dorsal Root Ganglion Stimulation. Int J Mol Sci 2024; 25:3591. [PMID: 38612402 PMCID: PMC11011701 DOI: 10.3390/ijms25073591] [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: 02/19/2024] [Revised: 03/12/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024] Open
Abstract
The dorsal root ganglion (DRG) serves as a pivotal site for managing chronic pain through dorsal root ganglion stimulation (DRG-S). In recent years, the DRG-S has emerged as an attractive modality in the armamentarium of neuromodulation therapy due to its accessibility and efficacy in alleviating chronic pain refractory to conventional treatments. Despite its therapeutic advantages, the precise mechanisms underlying DRG-S-induced analgesia remain elusive, attributed in part to the diverse sensory neuron population within the DRG and its modulation of both peripheral and central sensory processing pathways. Emerging evidence suggests that DRG-S may alleviate pain by several mechanisms, including the reduction of nociceptive signals at the T-junction of sensory neurons, modulation of pain gating pathways within the dorsal horn, and regulation of neuronal excitability within the DRG itself. However, elucidating the full extent of DRG-S mechanisms necessitates further exploration, particularly regarding its supraspinal effects and its interactions with cognitive and affective networks. Understanding these mechanisms is crucial for optimizing neurostimulation technologies and improving clinical outcomes of DRG-S for chronic pain management. This review provides a comprehensive overview of the DRG anatomy, mechanisms of action of the DRG-S, and its significance in neuromodulation therapy for chronic pain.
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Affiliation(s)
- Alaa Abd-Elsayed
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53792, USA
| | - Swarnima Vardhan
- Department of Internal Medicine, Yale New Haven Health, Bridgeport Hospital, Bridgeport, CT 06605, USA; (S.V.); (A.A.)
- Advanced Spine on Park Avenue, New York, NY 10461, USA;
| | - Abhinav Aggarwal
- Department of Internal Medicine, Yale New Haven Health, Bridgeport Hospital, Bridgeport, CT 06605, USA; (S.V.); (A.A.)
| | - Madhurima Vardhan
- Argonne Leadership Computing Facility, Argonne National Laboratory, Lemont, IL 60439, USA;
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Shan L, Xu K, Ji L, Zeng Q, Liu Y, Wu Y, Chen Y, Li Y, Hu Q, Wu J, Xu Y, Luo Y, Li C, Wu C, Jiang C, Wang Z. Injured sensory neurons-derived galectin-3 contributes to neuropathic pain via programming microglia in the spinal dorsal horn. Brain Behav Immun 2024; 117:80-99. [PMID: 38190982 DOI: 10.1016/j.bbi.2024.01.002] [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: 09/19/2023] [Revised: 12/11/2023] [Accepted: 01/03/2024] [Indexed: 01/10/2024] Open
Abstract
Emerging studies have demonstrated spinal microglia play a critical role in central sensitization and contribute to chronic pain. Although several mediators that contribute to microglia activation have been identified, the mechanism of microglia activation and its functionally diversified mechanisms in pathological pain are still unclear. Here we report that injured sensory neurons-derived Galectin-3 (Gal3) activates and reprograms microglia in the spinal dorsal horn (SDH) and contributes to neuropathic pain. Firstly, Gal3 is predominantly expressed in the isolectin B4 (IB4)-positive non-peptidergic sensory neurons and significantly up-regulated in dorsal root ganglion (DRG) neurons and primary afferent terminals in SDH in the partial sciatic nerve ligation (pSNL)-induced neuropathic pain model. Gal3 knockout (Gal3 KO) mice showed a significant decrease in mechanical allodynia and Gal3 inhibitor TD-139 produced a significant anti-allodynia effect in the pSNL model. Furthermore, pSNL-induced microgliosis was compromised in Gal3 KO mice. Additionally, intrathecal injection of Gal3 produces remarkable mechanical allodynia by direct activation of microglia, which have enhanced inflammatory responses with TNF-α and IL-1β up-regulation. Thirdly, using single-nuclear RNA sequencing (snRNA-seq), we identified that Gal3 targets microglia and induces reprogramming of microglia, which may contribute to neuropathic pain establishment. Finally, Gal3 enhances excitatory synaptic transmission in excitatory neurons in the SDH via microglia activation. Our findings reveal that injured sensory neurons-derived Gal3 programs microglia in the SDH and contribute to neuropathic pain.
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Affiliation(s)
- Leyan Shan
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Kangtai Xu
- Department of Anesthesiology, Shenzhen People's Hospital, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Luyao Ji
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Qian Zeng
- Department of Anesthesiology, Shenzhen People's Hospital, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, The 6th Affiliated Hospital of Shenzhen University Medical School, Shenzhen, Guangdong, China
| | - Yaqi Liu
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yifei Wu
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yiming Chen
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yitong Li
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Qiaodan Hu
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Jiawei Wu
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yuanfan Xu
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yuhui Luo
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, The 6th Affiliated Hospital of Shenzhen University Medical School, Shenzhen, Guangdong, China
| | - Changlin Li
- Guangdong Institute of Intelligence Science and Technology, Hengqin, Zhuhai, Guangdong, China
| | - Chaoran Wu
- Department of Anesthesiology, Shenzhen People's Hospital, The First Affiliated Hospital, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Changyu Jiang
- Department of Pain Medicine and Shenzhen Municipal Key Laboratory for Pain Medicine, The 6th Affiliated Hospital of Shenzhen University Medical School, Shenzhen, Guangdong, China.
| | - Zilong Wang
- Department of Medical Neuroscience, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Key University Laboratory of Metabolism and Health of Guangdong School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; SUSTech Center for Pain Medicine, School of Medicine, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
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10
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Rankin G, Chirila AM, Emanuel AJ, Zhang Z, Woolf CJ, Drugowitsch J, Ginty DD. Nerve injury disrupts temporal processing in the spinal cord dorsal horn through alterations in PV + interneurons. Cell Rep 2024; 43:113718. [PMID: 38294904 PMCID: PMC11101906 DOI: 10.1016/j.celrep.2024.113718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 11/13/2023] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
How mechanical allodynia following nerve injury is encoded in patterns of neural activity in the spinal cord dorsal horn (DH) remains incompletely understood. We address this in mice using the spared nerve injury model of neuropathic pain and in vivo electrophysiological recordings. Surprisingly, despite dramatic behavioral over-reactivity to mechanical stimuli following nerve injury, an overall increase in sensitivity or reactivity of DH neurons is not observed. We do, however, observe a marked decrease in correlated neural firing patterns, including the synchrony of mechanical stimulus-evoked firing, across the DH. Alterations in DH temporal firing patterns are recapitulated by silencing DH parvalbumin+ (PV+) interneurons, previously implicated in mechanical allodynia, as are allodynic pain-like behaviors. These findings reveal decorrelated DH network activity, driven by alterations in PV+ interneurons, as a prominent feature of neuropathic pain and suggest restoration of proper temporal activity as a potential therapeutic strategy to treat chronic neuropathic pain.
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Affiliation(s)
- Genelle Rankin
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Anda M Chirila
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Alan J Emanuel
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Zihe Zhang
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Clifford J Woolf
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jan Drugowitsch
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
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11
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Chen X, Tang SJ. Neural Circuitry Polarization in the Spinal Dorsal Horn (SDH): A Novel Form of Dysregulated Circuitry Plasticity during Pain Pathogenesis. Cells 2024; 13:398. [PMID: 38474361 PMCID: PMC10930392 DOI: 10.3390/cells13050398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
Pathological pain emerges from nociceptive system dysfunction, resulting in heightened pain circuit activity. Various forms of circuitry plasticity, such as central sensitization, synaptic plasticity, homeostatic plasticity, and excitation/inhibition balance, contribute to the malfunction of neural circuits during pain pathogenesis. Recently, a new form of plasticity in the spinal dorsal horn (SDH), named neural circuit polarization (NCP), was discovered in pain models induced by HIV-1 gp120 and chronic morphine administration. NCP manifests as an increase in excitatory postsynaptic currents (EPSCs) in excitatory neurons and a decrease in EPSCs in inhibitory neurons, presumably facilitating hyperactivation of pain circuits. The expression of NCP is associated with astrogliosis. Ablation of reactive astrocytes or suppression of astrogliosis blocks NCP and, concomitantly, the development of gp120- or morphine-induced pain. In this review, we aim to compare and integrate NCP with other forms of plasticity in pain circuits to improve the understanding of the pathogenic contribution of NCP and its cooperation with other forms of circuitry plasticity during the development of pathological pain.
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Affiliation(s)
| | - Shao-Jun Tang
- Stony Brook University Pain and Anesthesia Research Center (SPARC), Department of Anesthesiology, Stony Brook University, Stony Brook, NY 11794, USA;
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12
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Wahezi SE, Caparo MA, Malhotra R, Sundaram L, Batti K, Ejindu P, Veeramachaneni R, Anitescu M, Hunter CW, Naeimi T, Farah F, Kohan L. Current Waveforms in Spinal Cord Stimulation and Their Impact on the Future of Neuromodulation: A Scoping Review. Neuromodulation 2024; 27:47-58. [PMID: 38184341 DOI: 10.1016/j.neurom.2023.11.002] [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: 09/10/2023] [Revised: 10/16/2023] [Accepted: 11/13/2023] [Indexed: 01/08/2024]
Abstract
BACKGROUND Neuromodulation is a standard and well-accepted treatment for chronic refractory neuropathic pain. There has been progressive innovation in the field over the last decade, particularly in areas of spinal cord stimulation (SCS) and dorsal root ganglion stimulation. Improved outcomes using proprietary waveforms have become customary in the field, leading to an unprecedented expansion of these products and a plethora of options for the management of pain. Although advances in waveform technology have improved our fundamental understanding of neuromodulation, a scoping review describing new energy platforms and their associated clinical effects and outcomes is needed. The authors submit that understanding electrophysiological neuromodulation may be important for clinical decision-making and programming selection for personalized patient care. OBJECTIVE This review aims to characterize ways differences in mechanism of action and clinical outcomes of current spinal neuromodulation products may affect contemporary clinical decision-making while outlining a possible path for the future SCS. STUDY DESIGN The study is a scoping review of the literature about newer generation SCS waveforms. MATERIALS AND METHODS A literature report was performed on PubMed and chapters to include articles on spine neuromodulation mechanism of action and efficacy. RESULTS A total of 8469 studies were identified, 75 of which were included for the scoping review after keywords defining recent waveform technology were added. CONCLUSIONS Clinical data suggest that neuromodulation remains a promising tool in the treatment of chronic pain. The evidence for SCS for treating chronic pain seems compelling; however, more long-term and comparative data are needed for a comparison of waveforms when it comes to the etiology of pain. In addition, an exploration into combination waveform therapy and waveform cycling may be paramount for future clinical studies and the development of new technologies.
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Affiliation(s)
- Sayed E Wahezi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA.
| | - Moorice A Caparo
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Ria Malhotra
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lakshman Sundaram
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Kevin Batti
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Prince Ejindu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | | | - Magdalena Anitescu
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Corey W Hunter
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Tahereh Naeimi
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Fadi Farah
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
| | - Lynn Kohan
- Multidisciplinary Pain Program, Montefiore Medical Center, Bronx, New York, USA
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13
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Charron A, Pepino L, Malapert P, Debrauwer V, Castets F, Salio C, Moqrich A. Sex-related exacerbation of injury-induced mechanical hypersensitivity in GAD67 haplodeficient mice. Pain 2024; 165:192-201. [PMID: 37578506 PMCID: PMC10723643 DOI: 10.1097/j.pain.0000000000003012] [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: 03/16/2023] [Revised: 05/13/2023] [Accepted: 06/05/2023] [Indexed: 08/15/2023]
Abstract
ABSTRACT Decreased GABA levels in injury-induced loss of spinal inhibition are still under intense interest and debate. Here, we show that GAD67 haplodeficient mice exhibited a prolonged injury-induced mechanical hypersensitivity in postoperative, inflammatory, and neuropathic pain models. In line with this, we found that loss of 1 copy of the GAD67-encoding gene Gad1 causes a significant decrease in GABA contents in spinal GABAergic neuronal profiles. Consequently, GAD67 haplodeficient males and females were unresponsive to the analgesic effect of diazepam. Remarkably, all these phenotypes were more pronounced in GAD67 haplodeficient females. These mice had significantly much lower amount of spinal GABA content, exhibited an exacerbated pain phenotype during the second phase of the formalin test, developed a longer lasting mechanical hypersensitivity in the chronic constriction injury of the sciatic nerve model, and were unresponsive to the pain relief effect of the GABA-transaminase inhibitor phenylethylidenehydrazine. Our study provides strong evidence for a role of GABA levels in the modulation of injury-induced mechanical pain and suggests a potential role of the GABAergic system in the prevalence of some painful diseases among females.
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Affiliation(s)
- Aude Charron
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Lucie Pepino
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Pascale Malapert
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Vincent Debrauwer
- Aix-Marseille-université, CNRS, Institut des Sciences Moléculaires de Marseille, UMR 7313, Campus Scientifique de St Jérôme, Marseille, France
| | - Francis Castets
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
| | - Chiara Salio
- Department of Veterinary Sciences, University of Turin, Grugliasco, Italy
| | - Aziz Moqrich
- Aix-Marseille-université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, Marseille, France
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14
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Fujiwara Y, Koga K, Nakamura NH, Maruo K, Tachibana T, Furue H. Optogenetic inhibition of spinal inhibitory neurons facilitates mechanical responses of spinal wide dynamic range neurons and causes mechanical hypersensitivity. Neuropharmacology 2024; 242:109763. [PMID: 37852319 DOI: 10.1016/j.neuropharm.2023.109763] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/06/2023] [Accepted: 10/14/2023] [Indexed: 10/20/2023]
Abstract
Inhibitory interneurons in the spinal dorsal horn (DH) play a major role in regulating innocuous and noxious information. Reduction in inhibitory synaptic transmission is thought to contribute to the development of touch-evoked pain (allodynia), a common symptom of neuropathic pain. However, it is not fully understood how inhibitory neurons in the DH regulate sensory responses in surrounding neurons and modulate sensory transmission. In this study, we established a novel experimental method to analyze temporal activity of DH neurons during the optogenetically induced disinhibition state by combining extracellular recording and optogenetics. We investigated how specific and temporally restricted dysfunction of DH inhibitory neurons affected spinal neuronal activities evoked by cutaneous mechanical stimulation. In behavioral experiments, the specific and temporally restricted spinal optogenetic suppression of DH inhibitory neurons induced mechanical hypersensitivity. Furthermore, this manipulation enhanced the mechanical responses of wide dynamic range (WDR) neurons, which are important for pain transmission, in response to brush and von Frey stimulation but not in response to nociceptive pinch stimulation. In addition, we examined whether a neuropathic pain medication, mirogabalin, suppressed these optogenetically induced abnormal pain responses. We found that mirogabalin treatment attenuated the abnormal firing responses of WDR neurons and mechanical hypersensitivity. These results suggest that temporally restricted and specific reduction of spinal inhibitory neuronal activity facilitates the mechanical responses of WDR neurons, resulting in neuropathic-like mechanical allodynia which can be suppressed by mirogabalin. Our optogenetic methods could be useful for developing novel therapeutics for neuropathic pain.
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Affiliation(s)
- Yuka Fujiwara
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan; Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
| | - Keisuke Koga
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan.
| | - Nozomu H Nakamura
- Department of Physiology, Hyogo Medical University, 1-1, Mukogawa, Nishinomiya, 663-8501, Japan
| | - Keishi Maruo
- Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
| | - Toshiya Tachibana
- Department of Orthopaedic Surgery, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan.
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo Medical University, 1-1 Mukogawa, Nishinomiya, 663-8501, Japan
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15
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Blažetić S, Krajina V, Labak I, Viljetić B, Pavić V, Ivić V, Balog M, Schnaar RL, Heffer M. Sialyltransferase Mutations Alter the Expression of Calcium-Binding Interneurons in Mice Neocortex, Hippocampus and Striatum. Int J Mol Sci 2023; 24:17218. [PMID: 38139047 PMCID: PMC10743413 DOI: 10.3390/ijms242417218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
Gangliosides are major glycans on vertebrate nerve cells, and their metabolic disruption results in congenital disorders with marked cognitive and motor deficits. The sialyltransferase gene St3gal2 is responsible for terminal sialylation of two prominent brain gangliosides in mammals, GD1a and GT1b. In this study, we analyzed the expression of calcium-binding interneurons in primary sensory (somatic, visual, and auditory) and motor areas of the neocortex, hippocampus, and striatum of St3gal2-null mice as well as St3gal3-null and St3gal2/3-double null. Immunohistochemistry with highly specific primary antibodies for GABA, parvalbumin, calretinin, and calbindin were used for interneuron detection. St3gal2-null mice had decreased expression of all three analyzed types of calcium-binding interneurons in all analyzed regions of the neocortex. These results implicate gangliosides GD1a and GT1b in the process of interneuron migration and maturation.
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Affiliation(s)
- Senka Blažetić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Vinko Krajina
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Irena Labak
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Barbara Viljetić
- Department of Chemistry, Biochemistry and Clinical Chemistry, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia;
| | - Valentina Pavić
- Department of Biology, Josip Juraj Strossmayer University of Osijek, Ulica cara Hadrijana 8A, 31000 Osijek, Croatia; (S.B.); (V.P.)
| | - Vedrana Ivić
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Marta Balog
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
| | - Ronald L. Schnaar
- Department of Pharmacology and Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA;
| | - Marija Heffer
- Department of Medical Biology, School of Medicine, Josip Juraj Strossmayer University of Osijek, 31000 Osijek, Croatia; (V.K.); (V.I.); (M.B.); (M.H.)
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16
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Pradier B, Segelcke D, Reichl S, Zahn PK, Pogatzki-Zahn EM. Spinal GABA transporter 1 contributes to evoked-pain related behavior but not resting pain after incision injury. Front Mol Neurosci 2023; 16:1282151. [PMID: 38130683 PMCID: PMC10734427 DOI: 10.3389/fnmol.2023.1282151] [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: 08/23/2023] [Accepted: 10/30/2023] [Indexed: 12/23/2023] Open
Abstract
The inhibitory function of GABA at the spinal level and its central modulation in the brain are essential for pain perception. However, in post-surgical pain, the exact mechanism and modes of action of GABAergic transmission have been poorly studied. This work aimed to investigate GABA synthesis and uptake in the incisional pain model in a time-dependent manner. Here, we combined assays for mechanical and heat stimuli-induced withdrawal reflexes with video-based assessments and assays for non-evoked (NEP, guarding of affected hind paw) and movement-evoked (MEP, gait pattern) pain-related behaviors in a plantar incision model in male rats to phenotype the effects of the inhibition of the GABA transporter (GAT-1), using a specific antagonist (NO711). Further, we determined the expression profile of spinal dorsal horn GAT-1 and glutamate decarboxylase 65/67 (GAD65/67) by protein expression analyses at four time points post-incision. Four hours after incision, we detected an evoked pain phenotype (mechanical, heat and movement), which transiently ameliorated dose-dependently following spinal inhibition of GAT-1. However, the NEP-phenotype was not affected. Four hours after incision, GAT-1 expression was significantly increased, whereas GAD67 expression was significantly reduced. Our data suggest that GAT-1 plays a role in balancing spinal GABAergic signaling in the spinal dorsal horn shortly after incision, resulting in the evoked pain phenotype. Increased GAT-1 expression leads to increased GABA uptake from the synaptic cleft and reduces tonic GABAergic inhibition at the post-synapse. Inhibition of GAT-1 transiently reversed this imbalance and ameliorated the evoked pain phenotype.
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Affiliation(s)
- Bruno Pradier
- Department of Anesthesiology, Operative Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany
| | - Daniel Segelcke
- Department of Anesthesiology, Operative Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany
| | - Sylvia Reichl
- Department of Anesthesiology, Operative Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany
| | - P. K. Zahn
- Department of Anesthesiology, Intensive Care and Pain Medicine, BG University Hospital Bergmannsheil, Ruhr-Universität Bochum, Bochum, Germany
| | - E. M. Pogatzki-Zahn
- Department of Anesthesiology, Operative Intensive Care and Pain Medicine, University Hospital Muenster, Muenster, Germany
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17
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Qi Y, Nelson TS, Prasoon P, Norris C, Taylor BK. Contribution of µ Opioid Receptor-expressing Dorsal Horn Interneurons to Neuropathic Pain-like Behavior in Mice. Anesthesiology 2023; 139:840-857. [PMID: 37566700 PMCID: PMC10840648 DOI: 10.1097/aln.0000000000004735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
BACKGROUND Intersectional genetics have yielded tremendous advances in our understanding of molecularly identified subpopulations and circuits within the dorsal horn in neuropathic pain. The authors tested the hypothesis that spinal µ opioid receptor-expressing neurons (Oprm1-expressing neurons) contribute to behavioral hypersensitivity and neuronal sensitization in the spared nerve injury model in mice. METHODS The authors coupled the use of Oprm1Cre transgenic reporter mice with whole cell patch clamp electrophysiology in lumbar spinal cord slices to evaluate the neuronal activity of Oprm1-expressing neurons in the spared nerve injury model of neuropathic pain. The authors used a chemogenetic approach to activate or inhibit Oprm1-expressing neurons, followed by the assessment of behavioral signs of neuropathic pain. RESULTS The authors reveal that spared nerve injury yielded a robust neuroplasticity of Oprm1-expressing neurons. Spared nerve injury reduced Oprm1 gene expression in the dorsal horn as well as the responsiveness of Oprm1-expressing neurons to the selective µ agonist (D-Ala2, N-MePhe4, Gly-ol)-enkephalin (DAMGO). Spared nerve injury sensitized Oprm1-expressing neurons, as reflected by an increase in their intrinsic excitability (rheobase, sham 38.62 ± 25.87 pA [n = 29]; spared nerve injury, 18.33 ± 10.29 pA [n = 29], P = 0.0026) and spontaneous synaptic activity (spontaneous excitatory postsynaptic current frequency in delayed firing neurons: sham, 0.81 ± 0.67 Hz [n = 14]; spared nerve injury, 1.74 ± 1.68 Hz [n = 10], P = 0.0466), and light brush-induced coexpression of the immediate early gene product, Fos in laminae I to II (%Fos/tdTomato+: sham, 0.42 ± 0.57% [n = 3]; spared nerve injury, 28.26 ± 1.92% [n = 3], P = 0.0001). Chemogenetic activation of Oprm1-expressing neurons produced mechanical hypersensitivity in uninjured mice (saline, 2.91 ± 1.08 g [n = 6]; clozapine N-oxide, 0.65 ± 0.34 g [n = 6], P = 0.0006), while chemogenetic inhibition reduced behavioral signs of mechanical hypersensitivity (saline, 0.38 ± 0.37 g [n = 6]; clozapine N-oxide, 1.05 ± 0.42 g [n = 6], P = 0.0052) and cold hypersensitivity (saline, 6.89 ± 0.88 s [n = 5] vs. clozapine N-oxide, 2.31 ± 0.52 s [n = 5], P = 0.0017). CONCLUSIONS The authors conclude that nerve injury sensitizes pronociceptive µ opioid receptor-expressing neurons in mouse dorsal horn. Nonopioid strategies to inhibit these interneurons might yield new treatments for neuropathic pain. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Yanmei Qi
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tyler S. Nelson
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Christopher Norris
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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18
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Ji H, Kim KR, Park JJ, Lee JY, Sim Y, Choi H, Kim S. Combination Gene Delivery Reduces Spinal Cord Pathology in Rats With Peripheral Neuropathic Pain. THE JOURNAL OF PAIN 2023; 24:2211-2227. [PMID: 37442406 DOI: 10.1016/j.jpain.2023.07.007] [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: 09/30/2022] [Revised: 06/25/2023] [Accepted: 07/06/2023] [Indexed: 07/15/2023]
Abstract
Although peripheral neuropathic pain is caused by peripheral nerve injury, it is not simply a peripheral nervous system disease. It causes abnormalities in both the central and peripheral nervous systems. Pathological phenomena, such as hyperactivation of sensory neurons and inflammation, are observed in both the dorsal root ganglion and spinal cord. Pain signals originating from the periphery are transmitted to the brain via the SC, and the signals are modulated by pathologically changing SC conditions. Therefore, the modulation of SC pathology is important for peripheral NP treatment. We investigated the effects of KLS-2031 (recombinant adeno-associated viruses expressing glutamate decarboxylase 65, glial cell-derived neurotrophic factor, and interleukin-10) delivered to the dorsal root ganglion on aberrant neuronal excitability and neuroinflammation in the SC of rats with peripheral NP. Results showed that KLS-2031 administration restored excessive excitatory transmission and inhibitory signals in substantia gelatinosa neurons. Moreover, KLS-2031 restored the in vivo hypersensitivity of wide dynamic range neurons and mitigated neuroinflammation in the SC by regulating microglia and astrocytes. Collectively, these findings demonstrated that KLS-2031 efficiently suppressed pathological pain signals and inflammation in the SC of peripheral NP model, and is a potential novel therapeutic approach for NP in clinical settings. PERSPECTIVE: Our study demonstrated that KLS-2031, a combination gene therapy delivered by transforaminal epidural injection, not only mitigates neuroinflammation but also improves SC neurophysiological function, including excitatory-inhibitory balance. These findings support the potential of KLS-2031 as a novel modality that targets multiple aspects of the complex pathophysiology of neuropathic pain.
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Affiliation(s)
- Hyelin Ji
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea
| | - Kyung-Ran Kim
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea
| | - Jang-Joon Park
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea
| | - Ju Youn Lee
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea
| | - Yeomoon Sim
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea; Business Development, Handok Inc., Seoul, Republic of Korea
| | - Heonsik Choi
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea; Healthcare Research Institute, Kolon Advanced Research Center, Kolon Industries, Seoul, Republic of Korea
| | - Sujeong Kim
- Institute of BioInnovation Research, Kolon Life Science, Seoul, Republic of Korea
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19
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Weiss T, Koehler H, Croy I. Pain and Reorganization after Amputation: Is Interoceptive Prediction a Key? Neuroscientist 2023; 29:665-675. [PMID: 35950521 PMCID: PMC10623598 DOI: 10.1177/10738584221112591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is an ongoing discussion on the relevance of brain reorganization following amputation for phantom limb pain. Recent attempts to provide explanations for seemingly controversial findings-specifically, maladaptive plasticity versus persistent functional representation as a complementary process-acknowledged that reorganization in the primary somatosensory cortex is not sufficient to explain phantom limb pain satisfactorily. Here we provide theoretical considerations that might help integrate the data reviewed and suppose a possible additional driver of the development of phantom limb pain-namely, an error in interoceptive predictions to somatosensory sensations and movements of the missing limb. Finally, we derive empirically testable consequences based on our considerations to guide future research.
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Affiliation(s)
- Thomas Weiss
- Department of Psychology, Clinical Psychology, Friedrich Schiller University Jena, Jena, Germany
| | - Hanna Koehler
- Department of Psychology, Clinical Psychology, Friedrich Schiller University Jena, Jena, Germany
- Biomagnetic Center, Jena University Hospital, Jena, Germany
| | - Ilona Croy
- Department of Psychology, Clinical Psychology, Friedrich Schiller University Jena, Jena, Germany
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20
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Jevtovic-Todorovic V, Todorovic SM. The Role of Neuroactive Steroids in Analgesia and Anesthesia: An Interesting Comeback? Biomolecules 2023; 13:1654. [PMID: 38002336 PMCID: PMC10669813 DOI: 10.3390/biom13111654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/26/2023] Open
Abstract
Published evidence over the past few decades suggests that general anesthetics could be neurotoxins especially when administered at the extremes of age. The reported pathology is not only at the morphological level when examined in very young and aged brains, given that, importantly, newly developing evidence suggests a variety of behavioral impairments. Since anesthesia is unavoidable in certain clinical settings, we should consider the development of new anesthetics. A promising and safe solution could be a new family of anesthetics referred to as neuroactive steroids. In this review, we summarize the currently available evidence regarding their anesthetic and analgesic properties.
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Affiliation(s)
- Vesna Jevtovic-Todorovic
- Department of Anesthesiology, Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA;
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21
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Gilbert JE, Zhang T, Esteller R, Grill WM. Network model of nociceptive processing in the superficial spinal dorsal horn reveals mechanisms of hyperalgesia, allodynia, and spinal cord stimulation. J Neurophysiol 2023; 130:1103-1117. [PMID: 37727912 DOI: 10.1152/jn.00186.2023] [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: 05/09/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/21/2023] Open
Abstract
The spinal dorsal horn (DH) processes sensory information and plays a key role in transmitting nociception to supraspinal centers. Loss of DH inhibition during neuropathic pain unmasks a pathway from nonnociceptive Aβ-afferent inputs to superficial dorsal horn (SDH) nociceptive-specific (NS) projection neurons, and this change may contribute to hyperalgesia and allodynia. We developed and validated a computational model of SDH neuronal circuitry that links nonnociceptive Aβ-afferent inputs in lamina II/III to a NS projection neuron in lamina I via a network of excitatory interneurons. The excitatory pathway and the NS projection neuron were in turn gated by inhibitory interneurons with connections based on prior patch-clamp recordings. Changing synaptic weights in the computational model to replicate neuropathic pain states unmasked a low-threshold excitatory pathway to NS neurons similar to experimental recordings. Spinal cord stimulation (SCS) is an effective therapy for neuropathic pain, and accumulating experimental evidence indicates that NS neurons in the SDH also respond to SCS. Accounting for these responses may inform therapeutic improvements, and we quantified responses to SCS in the SDH network model and examined the role of different modes of inhibitory control in modulating NS neuron responses to SCS. We combined the SDH network model with a previously published model of the deep dorsal horn (DDH) and identified optimal stimulation frequencies across different neuropathic pain conditions. Finally, we found that SCS-generated inhibition did not completely suppress model NS activity during simulated pinch inputs, providing an explanation of why SCS does not eliminate acute pain.NEW & NOTEWORTHY Chronic pain is a severe public health problem that reduces the quality of life for those affected and exacts an enormous socio-economic burden worldwide. Spinal cord stimulation (SCS) is an effective treatment for chronic pain, but SCS efficacy has not significantly improved over time, in part because the mechanisms of action remain unclear. Most preclinical studies investigating pain and SCS mechanisms have focused on the responses of deep dorsal horn (DDH) neurons, but neural networks in the superficial dorsal horn (SDH) are also important for processing nociceptive information. This work synthesizes heterogeneous experimental recordings from the SDH into a computational model that replicates experimental responses and that can be used to quantify neuronal responses to SCS under neuropathic pain conditions.
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Affiliation(s)
- John E Gilbert
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
| | - Tianhe Zhang
- Neuromodulation Research and Advanced Concepts, Boston Scientific Neuromodulation, Valencia, California, United States
| | - Rosana Esteller
- Neuromodulation Research and Advanced Concepts, Boston Scientific Neuromodulation, Valencia, California, United States
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
- Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, United States
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States
- Department of Neurosurgery, Duke University School of Medicine, Durham, North Carolina, United States
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22
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Ballon Romero SS, Fuh LJ, Hung SY, Lee YC, Huang YC, Chien SY, Chen YH. Electroacupuncture exerts prolonged analgesic and neuroprotective effects in a persistent dental pain model induced by multiple dental pulp injuries: GABAergic interneurons-astrocytes interaction. Front Immunol 2023; 14:1213710. [PMID: 37954604 PMCID: PMC10639134 DOI: 10.3389/fimmu.2023.1213710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 10/03/2023] [Indexed: 11/14/2023] Open
Abstract
Pain within the trigeminal system, particularly dental pain, is poorly understood. This study aimed to determine whether single or multiple dental pulp injuries induce persistent pain, its association with trigeminal central nociceptive pathways and whether electroacupuncture (EA) provides prolonged analgesic and neuroprotective effects in a persistent dental pain model. Models of single dental pulp injury (SDPI) and multiple dental pulp injuries (MDPI) were used to induce trigeminal neuropathic pain. The signs of dental pain-related behavior were assessed using the mechanical head withdrawal threshold (HWT). Immunofluorescence and western blot protocols were used to monitor astrocyte activation, changes in apoptosis-related proteins, and GABAergic interneuron plasticity. SDPI mice exhibited an initial marked decrease in HWT from days one to 14, followed by progressive recovery from days 21 to 42. From days 49 to 70, the HWT increased and returned to the control values. In contrast, MDPI mice showed a persistent decrease in HWT from days one to 70. MDPI increased glial fibrillary acidic protein (GFAP) and decreased glutamine synthetase (GS) and glutamate transporter-1 (GLT1) expression in the Vi/Vc transition zone of the brainstem on day 70, whereas no changes in astrocytic markers were observed on day 70 after SDPI. Increased expression of cleaved cysteine-aspartic protease-3 (cleaved caspase-3) and Bcl-2-associated X protein (Bax), along with decreased B-cell lymphoma/leukemia 2 (Bcl-2), were observed at day 70 after MDPI but not after SDPI. The downregulation of glutamic acid decarboxylase (GAD65) expression was observed on day 70 only after MDPI. The effects of MDPI-induced lower HWT from days one to 70 were attenuated by 12 sessions of EA treatment (days one to 21 after MDPI). Changes in astrocytic GFAP, GS, and GLT-1, along with cleaved caspase-3, Bax, Bcl-2, and GAD65 expression observed 70 days after MDPI, were reversed by EA treatment. The results suggest that persistent dental pain in mice was induced by MDPI but not by SDPI. This effect was associated with trigeminal GABAergic interneuron plasticity along with morphological and functional changes in astrocytes. EA exerts prolonged analgesic and neuroprotective effects that might be associated with the modulation of neuron-glia crosstalk mechanisms.
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Affiliation(s)
| | - Lih-Jyh Fuh
- School of Dentistry, College of Dentistry, China Medical University, Taichung, Taiwan
| | - Shih-Ya Hung
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
- Division of Surgery, Department of Medical Research, China Medical University Hospital, Taichung, Taiwan
| | - Yu-Chen Lee
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
- Department of Acupuncture, China Medical University Hospital, Taichung, Taiwan
| | - Yu-Chuen Huang
- Department of Medical Research, China Medical University Hospital, School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Szu-Yu Chien
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Yi-Hung Chen
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
- Chinese Medicine Research Center, China Medical University, Taichung, Taiwan
- Department of Photonics and Communication Engineering, Asia University, Taichung, Taiwan
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23
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Zheng G, Ren J, Shang L, Bao Y. Role of autophagy in the pathogenesis and regulation of pain. Eur J Pharmacol 2023; 955:175859. [PMID: 37429517 DOI: 10.1016/j.ejphar.2023.175859] [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: 01/02/2023] [Revised: 06/08/2023] [Accepted: 06/15/2023] [Indexed: 07/12/2023]
Abstract
Pain is a ubiquitous and highly concerned clinical symptom, usually caused by peripheral or central nervous injury, tissue damage, or other diseases. The long-term existence of pain can seriously affect daily physical function and quality of life and produce great torture on the physiological and psychological levels. However, the complex pathogenesis of pain involving molecular mechanisms and signaling pathways has not been fully elucidated, and managing pain remains highly challenging. As a result, finding new targets to pursue effective and long-term pain treatment strategies is required and urgent. Autophagy is an intracellular degradation and recycling process that maintains tissue homeostasis and energy supply, which can be cytoprotective and is vital in maintaining neural plasticity and proper nervous system function. Much evidence has shown that autophagy dysregulation is linked to the emergence of neuropathic pain, such as postherpetic neuralgia and cancer-related pain. Autophagy has also been connected to pain caused by osteoarthritis and lumbar disc degeneration. It is worth noting that in recent years, studies on traditional Chinese medicine have also proved that several traditional Chinese medicine monomers involve autophagy in the mechanism of pain relief. Therefore, autophagy can serve as a potential regulatory target to provide new ideas and inspiration for pain management.
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Affiliation(s)
- Guangda Zheng
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
| | - Juanxia Ren
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China.
| | - Lu Shang
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China.
| | - Yanju Bao
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
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24
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Absalom NL, Lin SXN, Liao VWY, Chua HC, Møller RS, Chebib M, Ahring PK. GABA A receptors in epilepsy: Elucidating phenotypic divergence through functional analysis of genetic variants. J Neurochem 2023. [PMID: 37621067 DOI: 10.1111/jnc.15932] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/26/2023]
Abstract
Normal brain function requires a tightly regulated balance between excitatory and inhibitory neurotransmissions. γ-Aminobutyric acid type A (GABAA ) receptors represent the major class of inhibitory ion channels in the mammalian brain. Dysregulation of these receptors and/or their associated pathways is strongly implicated in the pathophysiology of epilepsy. To date, hundreds of different GABAA receptor subunit variants have been associated with epilepsy, making them a prominent cause of genetically linked epilepsy. While identifying these genetic variants is crucial for accurate diagnosis and effective genetic counselling, it does not necessarily lead to improved personalised treatment options. This is because the identification of a variant does not reveal how the function of GABAA receptors is affected. Genetic variants in GABAA receptor subunits can cause complex changes to receptor properties resulting in various degrees of gain-of-function, loss-of-function or a combination of both. Understanding how variants affect the function of GABAA receptors therefore represents an important first step in the ongoing development of precision therapies. Furthermore, it is important to ensure that functional data are produced using methodologies that allow genetic variants to be classified using clinical guidelines such as those developed by the American College of Medical Genetics and Genomics. This article will review the current knowledge in the field and provide recommendations for future functional analysis of genetic GABAA receptor variants.
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Affiliation(s)
- Nathan L Absalom
- School of Science, University of Western Sydney, Sydney, New South Wales, Australia
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Susan X N Lin
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Vivian W Y Liao
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Han C Chua
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, The Danish Epilepsy Centre, Filadelfia, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Mary Chebib
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Philip K Ahring
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
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25
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Xu Y, Moulding D, Jin W, Beggs S. Microglial phagocytosis mediates long-term restructuring of spinal GABAergic circuits following early life injury. Brain Behav Immun 2023; 111:127-137. [PMID: 37037363 DOI: 10.1016/j.bbi.2023.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/21/2023] [Accepted: 04/05/2023] [Indexed: 04/12/2023] Open
Abstract
Peripheral injury during the early postnatal period alters the somatosensory system, leading to behavioural hyperalgesia upon re-injury in adulthood. Spinal microglia have been implicated as the cellular mediators of this phenomenon, but the mechanism is unclear. We hypothesised that neonatal injury (1) alters microglial phagocytosis of synapses in the dorsal horn leading to long-term structural changes in neurons, and/or (2) trains microglia, leading to a stronger microglial response after re-injury in adulthood. Using hindpaw surgical incision as a model we showed that microglial density and phagocytosis increased in the dorsal horn region innervated by the hindpaw. Dorsal horn microglia increased engulfment of synapses following injury, with a preference for those expressing the vesicular GABA transporter VGAT and primary afferent A-fibre terminals in neonates. This led to a long-term reduction of VGAT density in the dorsal horn and reduced microglial phagocytosis of VGLUT2 terminals. We also saw an increase in apoptosis following neonatal injury, which was not limited to the dorsal horn suggesting that larger circuit wide changes are happening. In adults, hindpaw incision increased microglial engulfment of predominantly VGAT synapses but did not alter the engulfment of A-fibres. This engulfment was not affected by prior neonatal injury, suggesting that microglial phagocytosis was not trained. These results highlight microglial phagocytosis in the dorsal horn as an important physiological response towards peripheral injury with potential long-term consequences and reveals differences in microglial responses between neonates and adults.
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Affiliation(s)
- Yajing Xu
- University College London, United Kingdom
| | - Dale Moulding
- University College London, United Kingdom; UCL GOS Institute of Child Health, United Kingdom
| | | | - Simon Beggs
- University College London, United Kingdom; UCL GOS Institute of Child Health, United Kingdom.
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26
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Uta D, Takeuchi K, Fukano K, Kawamura H, Ito A. Effect of a Single Dose of Oxaliplatin on the Induction of Peripheral Neuropathy in a Rat Model: An in vivo Electrophysiological Study. Biol Pharm Bull 2023:b23-00263. [PMID: 37331804 DOI: 10.1248/bpb.b23-00263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
The anticancer drug oxaliplatin is associated with peripheral neuropathy as a side effect accompanied by mechanical and cold allodynia. Although the superficial layer of the spinal cord dorsal horn is known to receive information primarily from peripheral pain nerves, to our knowledge, no in vivo electrophysiological analyses have been conducted to determine whether oxaliplatin administration increases the excitability of superficial layer neurons. Therefore, in vivo extracellular recordings were performed to measure action potentials in the deep and superficial layers of the spinal cord dorsal horn in rats treated with a single dose (6 mg/kg) of oxaliplatin. Action potentials were produced by mechanical stimulation with von Frey filaments to the hindlimb receptive fields. The results revealed that the firing frequency of action potentials increased relative to the intensity of mechanical stimulation, and that both deep and superficial layer neurons in the spinal cord dorsal horn increased significantly in oxaliplatin-treated compared with vehicle-treated rats, especially in the superficial layer. Several superficial layer neurons showed spontaneous firing that was not seen in vehicle-treated rats. In addition, a clear increase was seen in the firing frequency of neurons in the superficial layer of oxaliplatin-treated rats in response to a cold stimulus (here, the addition of acetone to the hindlimb receptive field). This study suggests that the superficial spinal cord dorsal horn strongly reflects the pain pathophysiology in peripheral neuropathy induced by oxaliplatin administration, and that the superficial layer neurons are useful for in vivo electrophysiological analysis using this pathological model.
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Affiliation(s)
- Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama
| | - Keita Takeuchi
- Laboratory for Pharmacology, Pharmaceutical Research Center, Asahi Kasei Pharma Corp
| | - Keigo Fukano
- Laboratory for Pharmacology, Pharmaceutical Research Center, Asahi Kasei Pharma Corp
| | - Hinata Kawamura
- Laboratory for Pharmacology, Pharmaceutical Research Center, Asahi Kasei Pharma Corp
| | - Akitoshi Ito
- Laboratory for Pharmacology, Pharmaceutical Research Center, Asahi Kasei Pharma Corp
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27
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Rodríguez-Palma EJ, De la Luz-Cuellar YE, Islas-Espinoza AM, Félix-Leyva AE, Shiers SI, García G, Torres-Lopez JE, Delgado-Lezama R, Murbartián J, Price TJ, Granados-Soto V. Activation of α 6 -containing GABA A receptors induces antinociception under physiological and pathological conditions. Pain 2023; 164:948-966. [PMID: 36001074 PMCID: PMC9950299 DOI: 10.1097/j.pain.0000000000002763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 08/15/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The loss of GABAergic inhibition is a mechanism that underlies neuropathic pain. Therefore, rescuing the GABAergic inhibitory tone through the activation of GABA A receptors is a strategy to reduce neuropathic pain. This study was designed to elucidate the function of the spinal α 6 -containing GABA A receptor in physiological conditions and neuropathic pain in female and male rats. Results show that α 6 -containing GABA A receptor blockade or transient α 6 -containing GABA A receptor knockdown induces evoked hypersensitivity and spontaneous pain in naive female rats. The α 6 subunit is expressed in IB4 + and CGRP + primary afferent neurons in the rat spinal dorsal horn and dorsal root ganglia but not astrocytes. Nerve injury reduces α 6 subunit protein expression in the central terminals of the primary afferent neurons and dorsal root ganglia, whereas intrathecal administration of positive allosteric modulators of the α 6 -containing GABA A receptor reduces tactile allodynia and spontaneous nociceptive behaviors in female, but not male, neuropathic rats and mice. Overexpression of the spinal α 6 subunit reduces tactile allodynia and restores α 6 subunit expression in neuropathic rats. Positive allosteric modulators of the α 6 -containing GABA A receptor induces a greater antiallodynic effect in female rats and mice compared with male rats and mice. Finally, α 6 subunit is expressed in humans. This receptor is found in CGRP + and P2X3 + primary afferent fibers but not astrocytes in the human spinal dorsal horn. Our results suggest that the spinal α 6 -containing GABA A receptor has a sex-specific antinociceptive role in neuropathic pain, suggesting that this receptor may represent an interesting target to develop a novel treatment for neuropathic pain.
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Affiliation(s)
- Erick J. Rodríguez-Palma
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Yarim E. De la Luz-Cuellar
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Ana M. Islas-Espinoza
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Adalberto E. Félix-Leyva
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
- Facultad de Biología, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa, Mexico
| | - Stephanie I. Shiers
- School of Behavioral and Brain Sciences, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Guadalupe García
- Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Jorge E. Torres-Lopez
- Laboratorio de Mecanismos de Dolor, División Académica de Ciencias de la Salud, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico
| | - Rodolfo Delgado-Lezama
- Departamento de Fisiología, Biofísica y Neurociencias, Cinvestav, Zacatenco, Mexico City, Mexico
| | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
| | - Theodore J. Price
- School of Behavioral and Brain Sciences, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Cinvestav, South Campus, Mexico City, Mexico
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28
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Kuo SW, Zhang T, Esteller R, Grill WM. In Vivo Measurements reveal that both low- and high-frequency spinal cord stimulation heterogeneously modulate superficial dorsal horn neurons. Neuroscience 2023; 520:119-131. [PMID: 37085007 DOI: 10.1016/j.neuroscience.2023.04.010] [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: 07/20/2022] [Revised: 03/01/2023] [Accepted: 04/08/2023] [Indexed: 04/23/2023]
Abstract
Current sub-perception spinal cord stimulation (SCS) is characterized by the use of high-frequency pulses to achieve paresthesia-free analgesic effects. High-frequency SCS demonstrates distinctive properties from paresthesia-based SCS, such as a longer time course to response, implying the existence of alternative mechanism(s) of action beyond gate control theory. We quantified the responses to SCS of single neurons within the superficial dorsal horn (SDH), a structure in close proximity to SCS electrodes, to investigate the mechanisms underlying high-frequency SCS in 62 urethane-anesthetized male rats. Sciatic nerve stimulation was delivered to isolate lumbar SDH neurons with evoked C-fiber activity. The evoked C-fiber activity before and after the application of SCS was compared to quantify the effects of SCS across stimulation intensity and stimulation duration at three different stimulation frequencies. We observed heterogeneous responses of SDH neurons which depended primarily on the type of unit. Low-threshold units with spontaneous activity, putatively inhibitory interneurons, tended to be facilitated by SCS while the other unit types were suppressed. The effects of SCS were more prominent with increased stimulation duration from 30 s to 30 m across frequencies. Our results highlight the importance of inhibitory interneurons in modulating local circuits of the SDH and the importance of local circuit contributions to the analgesic mechanisms of SCS.
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Affiliation(s)
- Su-Wei Kuo
- Department of Biomedical Engineering, Duke University, Durham, NC
| | - Tianhe Zhang
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Rosana Esteller
- Division of Neuromodulation, Boston Scientific Corporation, CA
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC; Departments of Electrical and Computer Engineering, Neurobiology, and Neurosurgery, Duke University, Durham, NC.
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29
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Breitinger U, Breitinger HG. Excitatory and inhibitory neuronal signaling in inflammatory and diabetic neuropathic pain. Mol Med 2023; 29:53. [PMID: 37069517 PMCID: PMC10111846 DOI: 10.1186/s10020-023-00647-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 03/27/2023] [Indexed: 04/19/2023] Open
Abstract
Pain, although unpleasant, is an essential warning mechanism against injury and damage of the organism. An intricate network of specialised sensors and transmission systems contributes to reception, transmission and central sensitization of pain. Here, we briefly introduce some of the main aspects of pain signal transmission, including nociceptors and nociceptive signals, mechanisms of inflammatory and neuropathic pain, and the situation of diabetes-associated neuropathic pain. The role of glia-astrocytes, microglia, satellite glia cells-and their specific channels, transporters and signaling pathways is described. A focus is on the contribution of inhibitory synaptic signaling to nociception and a possible role of glycine receptors in glucose-mediated analgesia and treatment-induced diabetic neuropathy. Inhibitory receptors such as GABAA- and glycine receptors are important contributors to nociceptive signaling; their contribution to altered pain sensation in diabetes may be of clinical relevance, and they could be promising therapeutic targets towards the development of novel analgesics.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, New Cairo, 11835, Egypt
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30
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Rankin G, Chirila AM, Emanuel AJ, Zhang Z, Woolf CJ, Drugowitsch J, Ginty DD. Nerve injury disrupts temporal processing in the spinal cord dorsal horn through alterations in PV + interneurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.20.533541. [PMID: 36993199 PMCID: PMC10055222 DOI: 10.1101/2023.03.20.533541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
How mechanical allodynia following nerve injury is encoded in patterns of neural activity in the spinal cord dorsal horn (DH) is not known. We addressed this using the spared nerve injury model of neuropathic pain and in vivo electrophysiological recordings. Surprisingly, despite dramatic behavioral over-reactivity to mechanical stimuli following nerve injury, an overall increase in sensitivity or reactivity of DH neurons was not observed. We did, however, observe a marked decrease in correlated neural firing patterns, including the synchrony of mechanical stimulus-evoked firing, across the DH. Alterations in DH temporal firing patterns were recapitulated by silencing DH parvalbumin + (PV + ) inhibitory interneurons, previously implicated in mechanical allodynia, as were allodynic pain-like behaviors in mice. These findings reveal decorrelated DH network activity, driven by alterations in PV + interneurons, as a prominent feature of neuropathic pain, and suggest that restoration of proper temporal activity is a potential treatment for chronic neuropathic pain.
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31
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Zheng G, Ren J, Shang L, Bao Y. Sonic Hedgehog Signaling Pathway: A Role in Pain Processing. Neurochem Res 2023; 48:1611-1630. [PMID: 36738366 DOI: 10.1007/s11064-023-03864-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 02/05/2023]
Abstract
Pain, as one of the most prevalent clinical symptoms, is a complex physiological and psychological activity. Long-term severe pain can become unbearable to the body. However, existing treatments do not provide satisfactory results. Therefore, new mechanisms and therapeutic targets need to be urgently explored for pain management. The Sonic hedgehog (Shh) signaling pathway is crucial in embryonic development, cell differentiation and proliferation, and nervous system regulation. Here, we review the recent studies on the Shh signaling pathway and its action in multiple pain-related diseases. The Shh signaling pathway is dysregulated under various pain conditions, such as pancreatic cancer pain, bone cancer pain, chronic post-thoracotomy pain, pain caused by degenerative lumbar disc disease, and toothache. Further studies on the Shh signaling pathway may provide new therapeutic options for pain patients.
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Affiliation(s)
- Guangda Zheng
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beixiange 5, Xicheng District, Beijing, 100053, China
| | - Juanxia Ren
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China
| | - Lu Shang
- Liaoning University of Traditional Chinese Medicine, Shenyang, 110847, Liaoning Province, China
| | - Yanju Bao
- Department of Oncology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beixiange 5, Xicheng District, Beijing, 100053, China.
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32
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Encoding of inflammatory hyperalgesia in mouse spinal cord. Pain 2023; 164:443-460. [PMID: 36149026 DOI: 10.1097/j.pain.0000000000002727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/21/2022] [Indexed: 02/06/2023]
Abstract
ABSTRACT Inflammation modifies the input-output properties of peripheral nociceptive neurons such that the same stimulus produces enhanced nociceptive firing. This increased nociceptive output enters the superficial dorsal spinal cord (SDH), an intricate neuronal network composed largely of excitatory and inhibitory interneurons and a small percentage of projection neurons. The SDH network comprises the first central nervous system network integrating noxious information. Using in vivo calcium imaging and a computational approach, we characterized the responsiveness of the SDH network in mice to noxious stimuli in normal conditions and investigated the changes in SDH response patterns after acute burn injury-induced inflammation. We show that the application of noxious heat stimuli to the hind paw of naïve mice results in an overall increase in SDH network activity. Single-cell response analysis reveals that 70% of recorded neurons increase or suppress their activity, while ∼30% of neurons remain nonresponsive. After acute burn injury and the development of inflammatory hyperalgesia, application of the same noxious heat stimuli leads to the activation of previously nonresponding neurons and desuppression of suppressed neurons. We further demonstrate that an increase in afferent activity mimics the response of the SDH network to noxious heat stimuli under inflammatory conditions. Using a computational model of the SDH network, we predict that the changes in SDH network activity result in overall increased activity of excitatory neurons, amplifying the output from SDH to higher brain centers. We suggest that during acute local peripheral inflammation, the SDH network undergoes dynamic changes promoting hyperalgesia.
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Time-dependent and selective microglia-mediated removal of spinal synapses in neuropathic pain. Cell Rep 2023; 42:112010. [PMID: 36656715 DOI: 10.1016/j.celrep.2023.112010] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 09/20/2022] [Accepted: 01/03/2023] [Indexed: 01/20/2023] Open
Abstract
Neuropathic pain is a debilitating condition resulting from damage to the nervous system. Imbalance of spinal excitation and inhibition has been proposed to contribute to neuropathic pain. However, the structural basis of this imbalance remains unknown. Using a preclinical model of neuropathic pain, we show that microglia selectively engulf spinal synapses that are formed by central neurons and spare those of peripheral sensory neurons. Furthermore, we reveal that removal of inhibitory and excitatory synapses exhibits distinct temporal patterns, in which microglia-mediated inhibitory synapse removal precedes excitatory synapse removal. We also find selective and gradual increase in complement depositions on dorsal horn synapses that corresponds to the temporal pattern of microglial synapse pruning activity and type-specific synapse loss. Together, these results define a specific role for microglia in the progression of neuropathic pain pathogenesis and implicate these immune cells in structural remodeling of dorsal horn circuitry.
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Ca 2+-Permeable AMPA Receptors Contribute to Changed Dorsal Horn Neuronal Firing and Inflammatory Pain. Int J Mol Sci 2023; 24:ijms24032341. [PMID: 36768663 PMCID: PMC9916706 DOI: 10.3390/ijms24032341] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 01/26/2023] Open
Abstract
The dorsal horn (DH) neurons of the spinal cord play a critical role in nociceptive input integration and processing in the central nervous system. Engaged neuronal classes and cell-specific excitability shape nociceptive computation within the DH. The DH hyperexcitability (central sensitisation) has been considered a fundamental mechanism in mediating nociceptive hypersensitivity, with the proven role of Ca2+-permeable AMPA receptors (AMPARs). However, whether and how the DH hyperexcitability relates to changes in action potential (AP) parameters in DH neurons and if Ca2+-permeable AMPARs contribute to these changes remain unknown. We examined the cell-class heterogeneity of APs generated by DH neurons in inflammatory pain conditions to address these. Inflammatory-induced peripheral hypersensitivity increased DH neuronal excitability. We found changes in the AP threshold and amplitude but not kinetics (spike waveform) in DH neurons generating sustained or initial bursts of firing patterns. In contrast, there were no changes in AP parameters in the DH neurons displaying a single spike firing pattern. Genetic knockdown of the molecular mechanism responsible for the upregulation of Ca2+-permeable AMPARs allowed the recovery of cell-specific AP changes in peripheral inflammation. Selective inhibition of Ca2+-permeable AMPARs in the spinal cord alleviated nociceptive hypersensitivity, both thermal and mechanical modalities, in animals with peripheral inflammation. Thus, Ca2+-permeable AMPARs contribute to shaping APs in DH neurons and nociceptive hypersensitivity. This may represent a neuropathological mechanism in the DH circuits, leading to aberrant signal transfer to other nociceptive pathways.
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Jiang W, Zhang LX, Tan XY, Yu P, Dong M. Inflammation and histone modification in chronic pain. Front Immunol 2023; 13:1087648. [PMID: 36713369 PMCID: PMC9880030 DOI: 10.3389/fimmu.2022.1087648] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/29/2022] [Indexed: 01/15/2023] Open
Abstract
Increasing evidence suggests that epigenetic mechanisms have great potential in the field of pain. The changes and roles of epigenetics of the spinal cord and dorsal root ganglia in the chronic pain process may provide broad insights for future pain management. Pro-inflammatory cytokines and chemokines released by microglia and astrocytes, as well as blood-derived macrophages, play critical roles in inducing and maintaining chronic pain, while histone modifications may play an important role in inflammatory metabolism. This review provides an overview of neuroinflammation and chronic pain, and we systematically discuss the regulation of neuroinflammation and histone modifications in the context of chronic pain. Specifically, we analyzed the role of epigenetics in alleviating or exacerbating chronic pain by modulating microglia, astrocytes, and the proinflammatory mediators they release. This review aimed to contribute to the discovery of new therapeutic targets for chronic pain.
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Affiliation(s)
- Wei Jiang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Li-Xi Zhang
- Department of Thyroid Surgery, The First Hospital of Jilin University, Changchun, China
| | - Xuan-Yu Tan
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Peng Yu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, China,*Correspondence: Peng Yu, ; Ming Dong,
| | - Ming Dong
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China,*Correspondence: Peng Yu, ; Ming Dong,
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Jergova S, Dugan EA, Sagen J. Attenuation of SCI-Induced Hypersensitivity by Intensive Locomotor Training and Recombinant GABAergic Cells. BIOENGINEERING (BASEL, SWITZERLAND) 2023; 10:bioengineering10010084. [PMID: 36671656 PMCID: PMC9854592 DOI: 10.3390/bioengineering10010084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/30/2022] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
The underlying mechanisms of spinal cord injury (SCI)-induced chronic pain involve dysfunctional GABAergic signaling and enhanced NMDA signaling. Our previous studies showed that SCI hypersensitivity in rats can be attenuated by recombinant rat GABAergic cells releasing NMDA blocker serine-histogranin (SHG) and by intensive locomotor training (ILT). The current study combines these approaches and evaluates their analgesic effects on a model of SCI pain in rats. Cells were grafted into the spinal cord at 4 weeks post-SCI to target the chronic pain, and ILT was initiated 5 weeks post-SCI. The hypersensitivity was evaluated weekly, which was followed by histological and biochemical assays. Prolonged effects of the treatment were evaluated in subgroups of animals after we discontinued ILT. The results show attenuation of tactile, heat and cold hypersensitivity in all of the treated animals and reduced levels of proinflammatory cytokines IL1β and TNFα in the spinal tissue and CSF. Animals with recombinant grafts and ILT showed the preservation of analgesic effects even during sedentary periods when the ILT was discontinued. Retraining helped to re-establish the effect of long-term training in all of the groups, with the greatest impact being in animals with recombinant grafts. These findings suggest that intermittent training in combination with cell therapy might be an efficient approach to manage chronic pain in SCI patients.
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Albisetti GW, Ganley RP, Pietrafesa F, Werynska K, Magalhaes de Sousa M, Sipione R, Scheurer L, Bösl MR, Pelczar P, Wildner H, Zeilhofer HU. Inhibitory Kcnip2 neurons of the spinal dorsal horn control behavioral sensitivity to environmental cold. Neuron 2023; 111:92-105.e5. [PMID: 36323322 PMCID: PMC9831669 DOI: 10.1016/j.neuron.2022.10.008] [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: 10/08/2021] [Revised: 08/16/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2022]
Abstract
Proper sensing of ambient temperature is of utmost importance for the survival of euthermic animals, including humans. While considerable progress has been made in our understanding of temperature sensors and transduction mechanisms, the higher-order neural circuits processing such information are still only incompletely understood. Using intersectional genetics in combination with circuit tracing and functional neuron manipulation, we identified Kcnip2-expressing inhibitory (Kcnip2GlyT2) interneurons of the mouse spinal dorsal horn as critical elements of a neural circuit that tunes sensitivity to cold. Diphtheria toxin-mediated ablation of these neurons increased cold sensitivity without affecting responses to other somatosensory modalities, while their chemogenetic activation reduced cold and also heat sensitivity. We also show that Kcnip2GlyT2 neurons become activated preferentially upon exposure to cold temperatures and subsequently inhibit spinal nociceptive output neurons that project to the lateral parabrachial nucleus. Our results thus identify a hitherto unknown spinal circuit that tunes cold sensitivity.
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Affiliation(s)
- Gioele W. Albisetti
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Robert P. Ganley
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Francesca Pietrafesa
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Karolina Werynska
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | | | - Rebecca Sipione
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Louis Scheurer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland
| | - Michael R. Bösl
- Institute of Experimental Biomedicine I, University Hospital Würzburg, and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, 4001 Basel, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Corresponding author
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zürich, Switzerland,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland,Center for Neuroscience Zurich (ZNZ), 8057 Zürich, Switzerland,Drug Discovery Network Zurich (DDNZ), 8057 Zürich, Switzerland,Corresponding author
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Koga K, Kobayashi K, Tsuda M, Kubota K, Kitano Y, Furue H. Voltage-gated calcium channel subunit α 2δ-1 in spinal dorsal horn neurons contributes to aberrant excitatory synaptic transmission and mechanical hypersensitivity after peripheral nerve injury. Front Mol Neurosci 2023; 16:1099925. [PMID: 37033377 PMCID: PMC10076860 DOI: 10.3389/fnmol.2023.1099925] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/02/2023] [Indexed: 04/11/2023] Open
Abstract
Neuropathic pain, an intractable pain symptom that occurs after nerve damage, is caused by the aberrant excitability of spinal dorsal horn (SDH) neurons. Gabapentinoids, the most commonly used drugs for neuropathic pain, inhibit spinal calcium-mediated neurotransmitter release by binding to α2δ-1, a subunit of voltage-gated calcium channels, and alleviate neuropathic pain. However, the exact contribution of α2δ-1 expressed in SDH neurons to the altered synaptic transmission and mechanical hypersensitivity following nerve injury is not fully understood. In this study, we investigated which types of SDH neurons express α2δ-1 and how α2δ-1 in SDH neurons contributes to the mechanical hypersensitivity and altered spinal synaptic transmission after nerve injury. Using in situ hybridization technique, we found that Cacna2d1, mRNA coding α2δ-1, was mainly colocalized with Slc17a6, an excitatory neuronal marker, but not with Slc32a1, an inhibitory neuronal marker in the SDH. To investigate the role of α2δ-1 in SDH neurons, we used clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 system and showed that SDH neuron-specific ablation of Cacna2d1 alleviated mechanical hypersensitivity following nerve injury. We further found that excitatory post-synaptic responses evoked by electrical stimulation applied to the SDH were significantly enhanced after nerve injury, and that these enhanced responses were significantly decreased by application of mirogabalin, a potent α2δ-1 inhibitor, and by SDH neuron-specific ablation of Cacna2d1. These results suggest that α2δ-1 expressed in SDH excitatory neurons facilitates spinal nociceptive synaptic transmission and contributes to the development of mechanical hypersensitivity after nerve injury.
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Affiliation(s)
- Keisuke Koga
- Department of Neurophysiology, Hyogo Medical University, Nishinomiya, Japan
- Keisuke Koga,
| | - Kenta Kobayashi
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, Japan
| | - Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kazufumi Kubota
- Specialty Medicine Research Laboratories I, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | - Yutaka Kitano
- Specialty Medicine Research Laboratories I, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo Medical University, Nishinomiya, Japan
- *Correspondence: Hidemasa Furue,
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Hao H, Ramli R, Wang C, Liu C, Shah S, Mullen P, Lall V, Jones F, Shao J, Zhang H, Jaffe DB, Gamper N, Du X. Dorsal root ganglia control nociceptive input to the central nervous system. PLoS Biol 2023; 21:e3001958. [PMID: 36603052 PMCID: PMC9847955 DOI: 10.1371/journal.pbio.3001958] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 01/18/2023] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Accumulating observations suggest that peripheral somatosensory ganglia may regulate nociceptive transmission, yet direct evidence is sparse. Here, in experiments on rats and mice, we show that the peripheral afferent nociceptive information undergoes dynamic filtering within the dorsal root ganglion (DRG) and suggest that this filtering occurs at the axonal bifurcations (t-junctions). Using synchronous in vivo electrophysiological recordings from the peripheral and central processes of sensory neurons (in the spinal nerve and dorsal root), ganglionic transplantation of GABAergic progenitor cells, and optogenetics, we demonstrate existence of tonic and dynamic filtering of action potentials traveling through the DRG. Filtering induced by focal application of GABA or optogenetic GABA release from the DRG-transplanted GABAergic progenitor cells was specific to nociceptive fibers. Light-sheet imaging and computer modeling demonstrated that, compared to other somatosensory fiber types, nociceptors have shorter stem axons, making somatic control over t-junctional filtering more efficient. Optogenetically induced GABA release within DRG from the transplanted GABAergic cells enhanced filtering and alleviated hypersensitivity to noxious stimulation produced by chronic inflammation and neuropathic injury in vivo. These findings support "gating" of pain information by DRGs and suggest new therapeutic approaches for pain relief.
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Affiliation(s)
- Han Hao
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Rosmaliza Ramli
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
- School of Dental Sciences, Universiti Sains Malaysia, Kelantan, Malaysia
| | - Caixue Wang
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Chao Liu
- Department of Animal Care, Hebei Medical University; The Key Laboratory of Experimental Animal, Hebei Province; Shijiazhuang, China
| | - Shihab Shah
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Pierce Mullen
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Varinder Lall
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Frederick Jones
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Jicheng Shao
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
| | - David B. Jaffe
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, Texas, United States of America
| | - Nikita Gamper
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Shijiazhuang, China
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40
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Mechanisms behind the Development of Chronic Low Back Pain and Its Neurodegenerative Features. LIFE (BASEL, SWITZERLAND) 2022; 13:life13010084. [PMID: 36676033 PMCID: PMC9862392 DOI: 10.3390/life13010084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 12/11/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
Chronic back pain is complex and there is no guarantee that treating its potential causes will cause the pain to go away. Therefore, rather than attempting to "cure" chronic pain, many clinicians, caregivers and researchers aim to help educate patients about their pain and try to help them live a better quality of life despite their condition. A systematic review has demonstrated that patient education has a large effect on pain and pain related disability when done in conjunction with treatments. Therefore, understanding and updating our current state of knowledge of the pathophysiology of back pain is important in educating patients as well as guiding the development of novel therapeutics. Growing evidence suggests that back pain causes morphological changes in the central nervous system and that these changes have significant overlap with those seen in common neurodegenerative disorders. These similarities in mechanisms may explain the associations between chronic low back pain and cognitive decline and brain fog. The neurodegenerative underpinnings of chronic low back pain demonstrate a new layer of understanding for this condition, which may help inspire new strategies in pain education and management, as well as potentially improve current treatment.
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Kong Y, Kuss M, Shi Y, Fang F, Xue W, Shi W, Liu Y, Zhang C, Zhong P, Duan B. Exercise facilitates regeneration after severe nerve transection and further modulates neural plasticity. Brain Behav Immun Health 2022; 26:100556. [PMID: 36405423 PMCID: PMC9673108 DOI: 10.1016/j.bbih.2022.100556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/03/2022] [Accepted: 11/11/2022] [Indexed: 11/13/2022] Open
Abstract
Patients with severe traumatic peripheral nerve injury (PNI) always suffer from incomplete recovery and poor functional outcome. Physical exercise-based rehabilitation, as a non-invasive interventional strategy, has been widely acknowledged to improve PNI recovery by promoting nerve regeneration and relieving pain. However, effects of exercise on chronic plastic changes following severe traumatic PNIs have been limitedly discussed. In this study, we created a long-gap sciatic nerve transection followed by autograft bridging in rats and tested the therapeutic functions of treadmill running with low intensity and late initiation. We demonstrated that treadmill running effectively facilitated nerve regeneration and prevented muscle atrophy and thus improved sensorimotor functions and walking performance. Furthermore, exercise could reduce inflammation at the injured nerve as well as prevent the overexpression of TRPV1, a pain sensor, in primary afferent sensory neurons. In the central nervous system, we found that PNI induced transcriptive changes at the ipsilateral lumber spinal dorsal horn, and exercise could reverse the differential expression for genes involved in the Notch signaling pathway. In addition, through neural imaging techniques, we found volumetric, microstructural, metabolite, and neuronal activity changes in supraspinal regions of interest (i.e., somatosensory cortex, motor cortex, hippocampus, etc.) after the PNI, some of which could be reversed through treadmill running. In summary, treadmill running with late initiation could promote recovery from long-gap nerve transection, and while it could reverse maladaptive plasticity after the PNI, exercise may also ameliorate comorbidities, such as chronic pain, mental depression, and anxiety in the long term.
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Affiliation(s)
- Yunfan Kong
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Mitchell Kuss
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yu Shi
- School of Biological Sciences, University of Nebraska Lincoln, Lincoln, NE, 68588, USA
| | - Fang Fang
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wen Xue
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wen Shi
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yutong Liu
- Department of Radiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Chi Zhang
- School of Biological Sciences, University of Nebraska Lincoln, Lincoln, NE, 68588, USA
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Peng Zhong
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Bin Duan
- Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Department of Surgery, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
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Surround Inhibition Mediates Pain Relief by Low Amplitude Spinal Cord Stimulation: Modeling and Measurement. eNeuro 2022; 9:ENEURO.0058-22.2022. [PMID: 36150892 PMCID: PMC9536854 DOI: 10.1523/eneuro.0058-22.2022] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 08/31/2022] [Accepted: 09/17/2022] [Indexed: 12/15/2022] Open
Abstract
Low-frequency (<200 Hz), subperception spinal cord stimulation (SCS) is a novel modality demonstrating therapeutic efficacy for treating chronic neuropathic pain. When stimulation parameters were carefully titrated, patients experienced rapid onset (seconds-minutes) pain relief without paresthesia, but the mechanisms of action are unknown. Using an integrated computational model and in vivo measurements in urethane-anesthetized rats, we quantified how stimulation parameters (placement, pulse width, frequency, and amplitude) influenced dorsal column (DC) axon activation and neural responses in the dorsal horn (DH). Both modeled and recorded DC axons responded with irregular spiking patterns in response to low-amplitude SCS. Maximum inhibition of DH neurons occurred at ∼80% of the predicted sensory threshold in both modeled and recorded neurons, and responses were strongly dependent on spatially targeting of stimulation, i.e., the complement of DC axons activated, and on stimulation parameters. Intrathecal administration of bicuculline shifted neural responses to low-amplitude stimulation in both the model and experiment, suggesting that analgesia is dependent on segmental GABAergic mechanisms. Our results support the hypothesis that low-frequency subperception SCS generates rapid analgesia by activating a small number of DC axons which inhibit DH neuron activity via surround inhibition.
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Puja G, Losi G, Rovati L, Lanza M, Caselli G, Bardoni R. Modulation of NMDA receptor activity by CR4056, an imidazoline-2 receptor ligand with analgesic properties. FRONTIERS IN PAIN RESEARCH 2022; 3:1003068. [DOI: 10.3389/fpain.2022.1003068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
CR4056 is an imidazoline-2 receptor ligand having potent analgesic activity and synergistic effect with opioids. Very recently it has been found that CR4056 can revert the cognitive impairment in animal models of Alzheimer's disease (AD). Since several lines of evidence highlight the importance of NMDAR modulators in nociceptive signaling and in AD progression, we considered as important to investigate the effects of CR4056 on NMDAR activity. In primary culture of cortical neurons, application of NMDA and glycine elicits a current that is decreased in a dose-dependent fashion by CR4056 (IC50 5.3 ± 0.1 µM). CR4056 antagonism is reversible, not competitive and voltage-independent and it is not blocked by pertussis toxin. CR4056 interacts with the co-agonist glycine site in a competitive way, indeed high glycine concentrations diminish its effect. Fibroblasts expressing different recombinant NMDA receptors are differently modulated by CR4056: the potency and the efficacy of the compound are higher in GluN1- GluN2B than in GluN1-GluN2A containing receptors. In lamina II neurons of spinal cord slices, single stimulation of afferent fibers evokes an NMDA-mediated current that is inhibited by 10 µM CR4056. Repetitive stimulation of the dorsal root at high frequency and high intensity produces a firing activity that is significatively depressed by CR4056. Taken together, our results broad the understanding of the molecular mechanisms of CR4056 analgesic activity, involving the modulation of NMDAR activity. Therefore, we propose that the analgesic action of CR4056 and the neuroprotective effects in AD models may be mediated also by NMDAR inhibition.
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Jergova S, Hernandez M, Sagen J. Analgesic effect of recombinant GABAergic precursors releasing MVIIA in a model of peripheral nerve injury in rats. Mol Pain 2022; 18:17448069221129829. [PMID: 36113096 PMCID: PMC9513588 DOI: 10.1177/17448069221129829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Development of chronic pain has been attributed to dysfunctional GABA signaling in the
spinal cord. Direct pharmacological interventions on GABA signaling are usually not very
efficient and often accompanied by side effects due to the widespread distribution of GABA
receptors in CNS. Transplantation of GABAergic neuronal cells may restore the inhibitory
potential in the spinal cord. Grafted cells may also release additional analgesic peptides
by means of genetic engineering to further enhance the benefits of this approach.
Conopeptides are ideal candidates for recombinant expression using cell-based strategies.
The omega-conopeptide MVIIA is in clinical use for severe pain marketed as FDA approved
Prialt in the form of intrathecal injections. The goal of this study was to develop
transplantable recombinant GABAergic cells releasing conopeptide MVIIA and to evaluate the
analgesic effect of the grafts in a model of peripheral nerve injury-induced pain. We have
engineered and characterized the GABAergic progenitors expressing MVIIA. Recombinant and
nonrecombinant cells were intraspinally injected into animals after the nerve injury.
Animals were tested weekly up to 12 weeks for the presence of hypersensitivity, followed
by histochemical and biochemical analysis of the tissue. We observed beneficial effects of
the grafted cells in reducing hypersensitivity in all grafted animals, especially potent
in the recombinant group. The level of pain-related cytokines was reduced in the grafted
animals and correlation between these pain markers and actual behavior was indicated. This
study demonstrated the feasibility of recombinant cell transplantation in the management
of chronic pain.
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45
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Evaluating optimized temporal patterns of spinal cord stimulation (SCS). Brain Stimul 2022; 15:1051-1062. [DOI: 10.1016/j.brs.2022.07.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 06/30/2022] [Accepted: 07/19/2022] [Indexed: 11/18/2022] Open
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46
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Ohashi N, Uta D, Ohashi M, Baba H. Norepinephrine restores inhibitory tone of spinal lamina X circuitry, thus contributing to analgesia against inflammatory pain. Neuroscience 2022; 490:224-235. [DOI: 10.1016/j.neuroscience.2022.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/12/2022] [Accepted: 03/16/2022] [Indexed: 10/18/2022]
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Jemal B, Mohammed F, Tesema HG, Ahmed S, Mohammed A, Regasa T, Obsa MS. Analgesic Efficacy of Spinal Morphine in Comparison With Transversus Abdominis Plane Block for Postoperative Pain Management in Patients Undergoing Cesarean Section Under Spinal Anesthesia: A Randomized Controlled Trial. Front Med (Lausanne) 2022; 9:814538. [PMID: 35223910 PMCID: PMC8863940 DOI: 10.3389/fmed.2022.814538] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/04/2022] [Indexed: 11/27/2022] Open
Abstract
Background Cesarean section (CS) has been one of the most frequently performed major surgical interventions and causes severe postoperative pain. Spinal opioid and abdominal field block have been investigated as effective analgesia for postoperative pain and reduce the need for systemic medications and associated side effects. The aim of the current study is to compare spinal morphine (SM) and bilateral landmark oriented transversus abdominis plane (TAP) block for postoperative pain management. Method In this randomized controlled trial, 114 pregnant mothers scheduled for CS under spinal anesthesia were allocated randomly to receive either SM 0.1 mg (group SM; n = 56) or bilateral landmark-oriented TAP block with 20 ml of 0.25% of bupivacaine (group TAP; n = 52). A comparison of numerical variables between study groups was done using unpaired student t-test and Mann–Whitney test for symmetric and asymmetric data, respectively. Time to event variable was analyzed by using Kaplan–Meir's survival function. A p-value of < 0.05 was considered statistically significant. Result A total of 114 patients were recruited and randomly assigned and received interventions. Among them, 108 patients completed this study. Time to first analgesic request was significantly shorter in the TAP block compared to SM. Twenty-four-hour median morphine consumption was reduced in the SM group compared to the TAP block (p < 0.001). Median postoperative pain score during movement and rest shows statistically significant differences between groups (p < 0.001). Conclusion The addition of preservative-free 100 μg SM provides prolonged postoperative analgesia time, superior postoperative analgesia, and less postoperative opioid consumption compared to the TAP block.
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Affiliation(s)
- Bedru Jemal
- Department of Anesthesiology, College of Health Sciences and Medicine, Dilla University, Dilla, Ethiopia
| | - Fetiha Mohammed
- Department of Anesthesiology, College of Health Sciences and Medicine, Hawasa University, Dilla, Ethiopia
| | | | - Siraj Ahmed
- Department of Anesthesiology, College of Health Sciences and Medicine, Dilla University, Dilla, Ethiopia
| | - Ayub Mohammed
- Department of Anesthesia, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Teshome Regasa
- Department of Anesthesiology, College of Health Sciences and Medicine, Dilla University, Dilla, Ethiopia
| | - Mohammed Suleiman Obsa
- Department of Anesthesiology, College of Health Sciences and Medicine, Woliata Sodo University, Dilla, Ethiopia
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Oyama M, Watanabe S, Iwai T, Tanabe M. Distinct synaptic mechanisms underlying the analgesic effects of γ-aminobutyric acid transporter subtypes 1 and 3 inhibitors in the spinal dorsal horn. Pain 2022; 163:334-349. [PMID: 33990107 DOI: 10.1097/j.pain.0000000000002338] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/13/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Normalization of the excitatory and inhibitory balance by increasing the levels of endogenous inhibitory neurotransmitters by blocking their reuptake is a promising therapeutic strategy for relieving chronic pain. Pharmacological blockade of spinal γ-aminobutyric acid (GABA) transporter subtypes 1 and 3 (GAT1 and GAT3) has been reported to generate analgesic effects in animal models of neuropathic pain. Here, we explored the synaptic mechanisms underlying their analgesic effects in the spinal dorsal horn. Whole-cell recordings were made from dorsal horn neurons in spinal slices with attached dorsal roots from adult mice, and the effects of GAT inhibitors on miniature and evoked postsynaptic currents were examined. Behaviorally, GAT inhibitors were intrathecally applied to assess their effects on mechanical hypersensitivity in mice developing neuropathic pain after partial sciatic nerve ligation. The GAT1 inhibitor NNC-711 reduced the frequency of miniature excitatory postsynaptic currents (EPSCs) and the amplitude of C-fiber-mediated EPSCs, and the GAT3 inhibitor SNAP-5114 reduced the amplitude of A-fiber-mediated and C-fiber-mediated EPSCs. These effects were antagonized by the GABAB receptor antagonist CGP55845. Consistently, the analgesic effect of intrathecally injected NNC-711 and SNAP-5114 in mice developing mechanical hypersensitivity after partial sciatic nerve ligation was abolished by CGP55845. Thus, GAT1 and GAT3 inhibitors exert distinct GABAB receptor-mediated inhibitory effects on excitatory synaptic transmission in the spinal dorsal horn, which most likely contributes to their analgesic effects.
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Affiliation(s)
- Misa Oyama
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Shun Watanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Takashi Iwai
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
| | - Mitsuo Tanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, Tokyo, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, Minato-ku, Tokyo, Japan
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Fan W, Sullivan SJ, Sdrulla AD. Dorsal Column and Root Stimulation at Aβ-fiber Intensity Activate Superficial Dorsal Horn Glutamatergic and GABAergic Populations. Mol Pain 2022; 18:17448069221079559. [PMID: 35088625 PMCID: PMC8891844 DOI: 10.1177/17448069221079559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Neurostimulation therapies are frequently used in patients with chronic pain conditions. They emerged from Gate Control Theory (GCT), which posits that Aβ-fiber activation recruits superficial dorsal horn (SDH) inhibitory networks to “close the gate” on nociceptive transmission, resulting in pain relief. However, the efficacy of current therapies is limited, and the underlying circuits remain poorly understood. For example, it remains unknown whether ongoing stimulation of Aβ-fibers is sufficient to drive activity in SDH neurons. We used multiphoton microscopy in spinal cords extracted from mice expressing the genetically encoded calcium indicator GCaMP6s in glutamatergic and GABAergic populations; activity levels were inferred from deconvolved calcium signals using CaImAn software. Sustained Aβ-fiber stimulation at the dorsal columns or dorsal roots drove robust yet transient activation of both SDH populations. Following the initial increase, activity levels decreased below baseline in glutamatergic neurons and were depressed after stimulation ceased in both populations. Surprisingly, only about half of GABAergic neurons responded to Aβ-fiber stimulation. This subset showed elevated activity for the entire duration of stimulation, while non-responders decreased with time. Our findings suggest that Aβ-fiber stimulation initially recruits both excitatory and inhibitory populations but has divergent effects on their activity, providing a foundation for understanding the analgesic effects of neurostimulation devices. Perspective: This article used microscopy to characterize the responses of mouse spinal cord cells to stimulation of non-painful nerve fibers. These findings deepen our understanding of how the spinal cord processes information and provide a foundation for improving pain-relieving therapies.
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Affiliation(s)
- Wei Fan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Steve J Sullivan
- Anesthesiology and Pain Management6684Oregon Health & Science University
| | - Andrei D Sdrulla
- Anesthesiology and Pain Management6684Oregon Health & Science University
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Kearns A, Jayasi J, Liu X, Wang J, Shi Y, Chung JM, La JH, Tang SJ, Bae C. Neuron Type-Dependent Synaptic Activity in the Spinal Dorsal Horn of Opioid-Induced Hyperalgesia Mouse Model. Front Synaptic Neurosci 2021; 13:748929. [PMID: 34867259 PMCID: PMC8637419 DOI: 10.3389/fnsyn.2021.748929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/26/2021] [Indexed: 11/26/2022] Open
Abstract
Opioids are widely used for pain relief; however, chronic opioid use causes a paradoxical state of enhanced pain sensitivity, termed “Opioid-induced hyperalgesia (OIH).” Despite the clinical importance of OIH, the detailed mechanism by which it enhances pain sensitivity remains unclear. In this study, we tested whether repeated morphine induces a neuronal circuit polarization in the mouse spinal dorsal horn (SDH). Transgenic mice expressing GFP to neurokinin 1 receptor-expressing neurons (sNK1Rn) and GABAergic interneurons (sGABAn) that received morphine [20 mg/kg, once daily for four consecutive days (i.p.)] developed mechanical hypersensitivity. Repeated morphine altered synaptic strengths in the SDH as a specific cell-type but not in a gender-dependent manner. In sNK1Rn and non-tonic firing neurons, repeated morphine treatment significantly increased frequency of spontaneous excitatory postsynaptic current (sEPSC) and evoked EPSC (eEPSC). In addition, repeated morphine treatment significantly decreased evoked inhibitory postsynaptic current (eIPSC) in sNK1Rn. Conversely, in sGABAn and tonic firing neurons, repeated morphine treatment significantly decreased sEPSC frequency and eEPSC, but had no change of eIPSC in sGABAn. Interestingly, repeated morphine treatment significantly decreased neuronal rheobase of sNK1Rn but had no effect on sGABAn. These findings suggest that spinal neuronal circuit polarization maybe the mechanism of OIH and identify a potential therapeutic mechanism to prevent or treat opioid-induced pain.
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Affiliation(s)
- Austin Kearns
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States
| | - Jazmine Jayasi
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States
| | - Xin Liu
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jigong Wang
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Yuqiang Shi
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jin Mo Chung
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Jun-Ho La
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Shao-Jun Tang
- Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Chilman Bae
- School of Electrical, Computer, and Biomedical Engineering, Southern Illinois University, Carbondale, IL, United States.,Department of Neuroscience, Cell Biology, and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
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