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Song W, Jayaprakash N, Saleknezhad N, Puleo C, Al-Abed Y, Martin JH, Zanos S. Transspinal Focused Ultrasound Suppresses Spinal Reflexes in Healthy Rats. Neuromodulation 2024; 27:614-624. [PMID: 37530695 DOI: 10.1016/j.neurom.2023.04.476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 04/26/2023] [Accepted: 04/29/2023] [Indexed: 08/03/2023]
Abstract
OBJECTIVES Low-intensity, focused ultrasound (FUS) is an emerging noninvasive neuromodulation approach, with improved spatial and temporal resolution and penetration depth compared to other noninvasive electrical stimulation strategies. FUS has been used to modulate circuits in the brain and the peripheral nervous system, however, its potential to modulate spinal circuits is unclear. In this study, we assessed the effect of trans-spinal FUS (tsFUS) on spinal reflexes in healthy rats. MATERIALS AND METHODS tsFUS targeting different spinal segments was delivered for 1 minute, under anesthesia. Monosynaptic H-reflex of the sciatic nerve, polysynaptic flexor reflex of the sural nerve, and withdrawal reflex tested with a hot plate were measured before, during, and after tsFUS. RESULTS tsFUS reversibly suppresses the H-reflex in a spinal segment-, acoustic pressure- and pulse-repetition frequency (PRF)-dependent manner. tsFUS with high PRF augments the degree of homosynaptic depression of the H-reflex observed with paired stimuli. It suppresses the windup of components of the flexor reflex associated with slower, C-afferent, but not faster, A- afferent fibers. Finally, it increases the latency of the withdrawal reflex. tsFUS does not elicit neuronal loss in the spinal cord. CONCLUSIONS Our study provides evidence that tsFUS reversibly suppresses spinal reflexes and suggests that tsFUS could be a safe and effective strategy for spinal cord neuromodulation in disorders associated with hyperreflexia, including spasticity after spinal cord injury and painful syndromes.
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Affiliation(s)
- Weiguo Song
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Naveen Jayaprakash
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Nafiseh Saleknezhad
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Chris Puleo
- General Electric Research, Niskayuna, NY, USA
| | - Yousef Al-Abed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - John H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, USA
| | - Stavros Zanos
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA; Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY; Elmezzi Graduate School of Molecular Medicine, Manhasset, NY.
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2
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Zhang Z, Zheng H, Yu Q, Jing X. Understanding of Spinal Wide Dynamic Range Neurons and Their Modulation on Pathological Pain. J Pain Res 2024; 17:441-457. [PMID: 38318328 PMCID: PMC10840524 DOI: 10.2147/jpr.s446803] [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: 10/26/2023] [Accepted: 01/12/2024] [Indexed: 02/07/2024] Open
Abstract
The spinal dorsal horn (SDH) transmits sensory information from the periphery to the brain. Wide dynamic range (WDR) neurons within this relay site play a critical role in modulating and integrating peripheral sensory inputs, as well as the process of central sensitization during pathological pain. This group of spinal multi-receptive neurons has attracted considerable attention in pain research due to their capabilities for encoding the location and intensity of nociception. Meanwhile, transmission, processing, and modulation of incoming afferent information in WDR neurons also establish the underlying basis for investigating the integration of acupuncture and pain signals. This review aims to provide a comprehensive examination of the distinctive features of WDR neurons and their involvement in pain. Specifically, we will examine the regulation of diverse supraspinal nuclei on these neurons and analyze their potential in elucidating the mechanisms of acupuncture analgesia.
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Affiliation(s)
- Zhiyun Zhang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China
| | - Hao Zheng
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China
| | - Qingquan Yu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China
| | - Xianghong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China
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3
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Tran H, Feng Y, Chao D, Liu QS, Hogan QH, Pan B. Descending mechanism by which medial prefrontal cortex endocannabinoid signaling controls the development of neuropathic pain and neuronal activity of dorsal root ganglion. Pain 2024; 165:102-114. [PMID: 37463226 PMCID: PMC10787817 DOI: 10.1097/j.pain.0000000000002992] [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] [Received: 10/14/2022] [Accepted: 06/05/2023] [Indexed: 07/20/2023]
Abstract
ABSTRACT Although regulation of nociceptive processes in the dorsal horn by deep brain structures has long been established, the role of cortical networks in pain regulation is minimally explored. The medial prefrontal cortex (mPFC) is a key brain area in pain processing that receives ascending nociceptive input and exerts top-down control of pain sensation. We have shown critical changes in mPFC synaptic function during neuropathic pain, controlled by endocannabinoid (eCB) signaling. This study tests whether mPFC eCB signaling modulates neuropathic pain through descending control. Intra-mPFC injection of cannabinoid receptor type 1 (CB1R) agonist WIN-55,212-2 (WIN) in the chronic phase transiently alleviates the pain-like behaviors in spared nerve injury (SNI) rats. By contrast, intra-mPFC injection of CB1R antagonist AM4113 in the early phase of neuropathic pain reduces the development of pain-like behaviors in the chronic phase. Spared nerve injury reduced the mechanical threshold to induce action potential firing of dorsal horn wide-dynamic-range neurons, but this was reversed in rats by WIN in the chronic phase of SNI and by mPFC injection of AM4113 in the early phase of SNI. Elevated dorsal root ganglion neuronal activity after injury was also diminished in rats by mPFC injection of AM4113, potentially by reducing antidromic activity and subsequent neuronal inflammation. These findings suggest that depending on the phase of the pain condition, both blocking and activating CB1 receptors in the mPFC can regulate descending control of pain and affect both dorsal horn neurons and peripheral sensory neurons, contributing to changes in pain sensitivity.
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Affiliation(s)
- Hai Tran
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Yin Feng
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Dongman Chao
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Qing-song Liu
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Quinn H. Hogan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Bin Pan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
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4
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Petersen EA. Spinal cord stimulation in painful diabetic neuropathy: An overview. Diabetes Res Clin Pract 2023; 206 Suppl 1:110760. [PMID: 38245324 DOI: 10.1016/j.diabres.2023.110760] [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: 05/08/2023] [Accepted: 05/30/2023] [Indexed: 01/22/2024]
Abstract
Up to 25% of people with diabetes develop painful diabetic neuropathy (PDN). The standard of care pharmacotherapies for PDN have limited efficacy with a considerable side effect profile. Spinal cord stimulation (SCS) is a form of electrical neurostimulation that modulates neural function via electrodes implanted into the spinal epidural space. While low frequency SCS has been shown to be potentially effective for treating pain associated with neuropathies, it masks pain perception by inducing paresthesia. Compared to low frequency SCS, high frequency (10 kHz) SCS delivers paresthesia-free therapy. As was shown in a randomized controlled trial, SENZA-PDN (NCT03228420), 10 kHz SCS is safe and effective for the treatment of painful diabetic neuropathy. 10 kHz SCS offered a comprehensive treatment that improved pain levels, sleep, quality of life, and neurological function. These improvements correlated with a high degree of patient satisfaction. 10 kHz SCS provides a safe, durable and effective treatment for PDN with the unique potential to improve neurological function. In patients for whom durable, effective treatments have been limited thus far, the findings of the SENZA-PDN study are encouraging.
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Affiliation(s)
- Erika A Petersen
- University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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5
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Wilhelm M, Cleland J, Carroll A, Marinch M, Imhoff M, Severini N, Donaldson M. The combined effects of manual therapy and exercise on pain and related disability for individuals with nonspecific neck pain: A systematic review with meta-analysis. J Man Manip Ther 2023; 31:393-407. [PMID: 37092822 PMCID: PMC10642331 DOI: 10.1080/10669817.2023.2202895] [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: 10/13/2022] [Accepted: 04/07/2023] [Indexed: 04/25/2023] Open
Abstract
BACKGROUND Neck pain is among the most prevalent and costly musculoskeletal disorders. Manual therapy and exercise are two standard treatment approaches to manage neck pain. In addition, clinical practice guidelines recommend a multi-modal approach, including both manual therapy and exercise for the treatment of neck pain; however, the specific effects of these combined interventions have not recently been reported in the literature. OBJECTIVE To perform a systematic review and meta-analysis to determine the effect of manual therapy combined with exercise on pain, disability, and quality of life in individuals with nonspecific neck pain. DESIGN Systematic Review and Meta-Analysis. METHODS Electronic database searches were completed in PubMed, CINAHL, Cochrane, EMBASE, Ovid, and SportDiscus, with publication dates of January 2000 to December 2022. The risk of bias in the included articles was completed using the Revised Cochrane Risk of Bias Tool (RoB 2). Raw data were pooled using standardized mean differences and mean differences for pain, disability, and quality of life outcomes, and forest plots were computed in the meta-analysis. RESULTS Twenty-two studies were included in the final review. With moderate certainty of evidence, three studies demonstrated no significant difference between manual therapy plus exercise and manual therapy alone in pain (SMD of -0.25 (95% CI: -0.52, 0.02)) or disability (-0.37 (95% CI: -0.92, 0.18)). With a low certainty of evidence, 16 studies demonstrated that manual therapy plus exercise is significantly better than exercise alone for reducing pain (-0.95 (95%CI: -1.38, -0.51)). Similarly, with low certainty of evidence, 13 studies demonstrated that manual therapy plus exercise is significantly better than exercise alone for reducing disability (-0.59 (95% CI: -0.90, -0.28)). Four studies demonstrated that manual therapy plus exercise is significantly better than a control intervention for reducing pain (moderate certainty) (-2.15 (95%CI: -3.58, -0.73)) and disability (low certainty) (-2.39 (95% CI: -3.80, -0.98)). With a high certainty of evidence, four studies demonstrated no significant difference between manual therapy plus exercise and exercise alone in quality of life (SMD of -0.02 (95% CI: -0.21, 0.18)). CONCLUSION Based on this systematic review and meta-analysis, a multi-modal treatment approach including exercise and manual therapy appears to provide similar effects as manual therapy alone, but is more effective than exercise alone or other interventions (control, placebo, 'conventional physical therapy', etc.) for the treatment of nonspecific neck pain and related disability. Some caution needs to be taken when interpreting these results given the general low to moderate certainty of the quality of the evidence.
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Affiliation(s)
- Mark Wilhelm
- Physical Therapy Program, Tufts University, Boston, MA, USA
| | - Joshua Cleland
- Physical Therapy Program, Tufts University, Boston, MA, USA
| | | | - Mark Marinch
- Physical Therapy Program, Tufts University, Boston, MA, USA
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6
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Sago T, Costa YM, Ferreira DM, Svensson P, Exposto FG. Referred sensations in the orofacial region are associated with a decreased descending pain inhibition and modulated by remote noxious stimuli and local anesthesia. Pain 2023; 164:2228-2238. [PMID: 37289580 DOI: 10.1097/j.pain.0000000000002921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 01/03/2023] [Indexed: 06/10/2023]
Abstract
ABSTRACT Referred sensation (RS) as a specific clinical phenomenon has been known for a long time, although the underlying mechanisms remain unclear. The aims of this study were to assess if (1) healthy individuals who experienced RS had a less active endogenous pain system when compared with those who did not; (2) activation of descending pain inhibition mechanisms can modulate RS parameters; and finally, (3) a transient decrease in peripheral afferent input because of a local anesthetic (LA) block in the masseter muscle can modulate RS parameters. To assess these, 50 healthy participants were assessed in 3 different sessions. In the first session, conditioned pain modulation (CPM) as well as mechanical sensitivity and RS at the masseter muscle were assessed. In the same session, participants who experienced RS had their mechanical sensitivity and RS assessed again while undergoing a CPM protocol. In the second and third sessions, participants had their mechanical sensitivity and RS assessed before and after receiving an injection of 2 mL of LA and isotonic saline into the masseter muscle. The main findings of this study were (1) participants who experienced RS during standardized palpation exhibited increased mechanical sensitivity ( P < 0.05, Tukey post hoc test) and decreased CPM ( P < 0.05, Tukey post hoc test) when compared with those who did not; RS incidence ( P < 0.05, Cochran Q test), frequency ( P < 0.05; Friedman test), intensity ( P < 0.05, Tukey post hoc test), and area ( P < 0.05, Tukey post hoc test) were all significantly reduced when assessed (2) during a painful conditioning stimulus and (3) after LA block. These novel findings highlight that RS in the orofacial region are strongly modified by both peripheral and central nervous system factors.
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Affiliation(s)
- Teppei Sago
- Division of Dental Anesthesiology, Department of Science of Physical Functions, Kyushu Dental University, Fukuoka, Japan
| | - Yuri M Costa
- Department of Biosciences, Piracicaba Dental School, University of Campinas, Piracicaba, Brazil
| | - Dyna M Ferreira
- Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - Peter Svensson
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark
- Faculty of Odontology, Malmo University, Malmo, Sweden
| | - Fernando G Exposto
- Section for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Health, Aarhus University, Aarhus, Denmark
- Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus, Denmark
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7
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Buhidma Y, Hobbs C, Malcangio M, Duty S. Periaqueductal grey and spinal cord pathology contribute to pain in Parkinson's disease. NPJ Parkinsons Dis 2023; 9:69. [PMID: 37100804 PMCID: PMC10133233 DOI: 10.1038/s41531-023-00510-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/11/2023] [Indexed: 04/28/2023] Open
Abstract
Pain is a key non-motor feature of Parkinson's disease (PD) that significantly impacts on life quality. The mechanisms underlying chronic pain in PD are poorly understood, hence the lack of effective treatments. Using the 6-hydroxydopamine (6-OHDA) lesioned rat model of PD, we identified reductions in dopaminergic neurons in the periaqueductal grey (PAG) and Met-enkephalin in the dorsal horn of the spinal cord that were validated in human PD tissue samples. Pharmacological activation of D1-like receptors in the PAG, identified as the DRD5+ phenotype located on glutamatergic neurons, alleviated the mechanical hypersensitivity seen in the Parkinsonian model. Downstream activity in serotonergic neurons in the Raphé magnus (RMg) was also reduced in 6-OHDA lesioned rats, as detected by diminished c-FOS positivity. Furthermore, we identified increased pre-aggregate α-synuclein, coupled with elevated activated microglia in the dorsal horn of the spinal cord in those people that experienced PD-related pain in life. Our findings have outlined pathological pathways involved in the manifestation of pain in PD that may present targets for improved analgesia in people with PD.
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Affiliation(s)
- Yazead Buhidma
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, SE1 1UL, UK
| | - Carl Hobbs
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, SE1 1UL, UK
| | - Marzia Malcangio
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, SE1 1UL, UK
| | - Susan Duty
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Wolfson Centre for Age-Related Diseases, Guy's Campus, London, SE1 1UL, UK.
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Beauchene C, Zurn CA, Ehrens D, Duff I, Duan W, Caterina M, Guan Y, Sarma SV. Steering Toward Normative Wide-Dynamic-Range Neuron Activity in Nerve-Injured Rats With Closed-Loop Peripheral Nerve Stimulation. Neuromodulation 2023; 26:552-562. [PMID: 36402658 PMCID: PMC10081946 DOI: 10.1016/j.neurom.2022.09.011] [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: 07/02/2022] [Revised: 09/08/2022] [Accepted: 09/30/2022] [Indexed: 11/18/2022]
Abstract
OBJECTIVES Chronic pain is primarily treated with pharmaceuticals, but the effects remain unsatisfactory. A promising alternative therapy is peripheral nerve stimulation (PNS), but it has been associated with suboptimal efficacy because its modulation mechanisms are not clear and the current therapies are primarily open loop (ie, manually adjusting the stimulation parameters). In this study, we developed a proof-of-concept computational modeling as the first step toward implementing closed-loop PNS in future biological studies. When developing new pain therapies, a useful pain biomarker is the wide-dynamic-range (WDR) neuron activity in the dorsal horn. In healthy animals, the WDR neuron activity occurs in a stereotyped manner; however, this response profile can vary widely after nerve injury to create a chronic pain condition. We hypothesized that if injury-induced changes of neuronal response can be normalized to resemble those of a healthy condition, the pathological aspects of pain may be treated while maintaining protective physiological nociception. MATERIALS AND METHODS Using an in vivo electrophysiology data set of WDR neuron recordings obtained in nerve-injured rats and naïve rats, we constructed sets of linear phenomenologic models of WDR firing rate during windup stimulation for both conditions. Then, we applied robust control systems techniques to identify a closed-loop PNS controller, which can drive the dynamics of WDR neuron response in neuropathic pain model into ranges associated with normal physiological pain. RESULTS The sets of identified linear models can accurately predict, in silico, nonlinear neural responses to electrical stimulation of the peripheral nerve. In addition, we showed that continuous closed-loop control of PNS can be used to normalize WDR neuron firing responses in three injured cases. CONCLUSIONS In this proof-of-concept study, we show how tractable, linear mathematical models of pain-related neurotransmission can be used to inform the development of closed-loop PNS. This new application of robust control to neurotechnology may also be expanded and applied across other neuromodulation applications.
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Affiliation(s)
- Christine Beauchene
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Claire A Zurn
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Daniel Ehrens
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Irina Duff
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Wanru Duan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael Caterina
- Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurosurgery, Neurosurgery Pain Research Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sridevi V Sarma
- Department of Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
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Chen Z, Huang Q, Song X, Ford NC, Zhang C, Xu Q, Lay M, He SQ, Dong X, Hanani M, Guan Y. Purinergic signaling between neurons and satellite glial cells of mouse dorsal root ganglia modulates neuronal excitability in vivo. Pain 2022; 163:1636-1647. [PMID: 35027518 PMCID: PMC9771604 DOI: 10.1097/j.pain.0000000000002556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 11/24/2021] [Indexed: 10/19/2022]
Abstract
ABSTRACT Primary sensory neurons in dorsal root ganglia (DRG) are wrapped by satellite glial cells (SGCs), and neuron-SGC interaction may affect somatosensation, especially nociceptive transmission. P2-purinergic receptors (P2Rs) are key elements in the two-way interactions between DRG neurons and SGCs. However, because the cell types are in such close proximity, conventional approaches such as in vitro culture and electrophysiologic recordings are not adequate to investigate the physiologically relevant responses of these cells at a population level. Here, we performed in vivo calcium imaging to survey the activation of hundreds of DRG neurons in Pirt-GCaMP6s mice and to assess SGC activation in GFAP-GCaMP6s mice in situ. By combining pharmacologic and electrophysiologic techniques, we investigated how ganglionic purinergic signaling initiated by α,β-methyleneadenosine 5'-triphosphate (α,β-MeATP) modulates neuronal activity and excitability at a population level. We found that α,β-MeATP induced robust activation of small neurons-likely nociceptors-through activation of P2X3R. Large neurons, which are likely non-nociceptive, were also activated by α,β-MeATP, but with a delay. Blocking pannexin 1 channels attenuated the late phase response of DRG neurons, indicating that P2R stimulation may subsequently induce paracrine ATP release, which could further activate cells in the ganglion. Moreover, ganglionic α,β-MeATP treatment in vivo sensitized small neurons and enhanced responses of spinal wide-dynamic-range neurons to subsequent C-fiber inputs, suggesting that modulation via ganglionic P2R signaling could significantly affect nociceptive neuron excitability and pain transmission. Therefore, targeting functional P2Rs within ganglia may represent an important new strategy for pain modulation.
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Affiliation(s)
- Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Qian Huang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Xiaodan Song
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Neil C. Ford
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Chi Zhang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Qian Xu
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Mark Lay
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD, United States
| | - Menachem Hanani
- Laboratory of Experimental Surgery, Hadassah-Hebrew University Medical Center, Faculty of Medicine, Hebrew University of Jerusalem, Mount Scopus, Jerusalem, Israel
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, the 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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10
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BzATP Activates Satellite Glial Cells and Increases the Excitability of Dorsal Root Ganglia Neurons In Vivo. Cells 2022; 11:cells11152280. [PMID: 35892578 PMCID: PMC9330736 DOI: 10.3390/cells11152280] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/18/2022] [Accepted: 07/21/2022] [Indexed: 12/14/2022] Open
Abstract
The purinergic system plays an important role in pain transmission. Recent studies have suggested that activation of P2-purinergic receptors (P2Rs) may be involved in neuron-satellite glial cell (SGC) interactions in the dorsal root ganglia (DRG), but the details remain unclear. In DRG, P2X7R is selectively expressed in SGCs, which closely surround neurons, and is highly sensitive to 3’-O-(4-Benzoyl) benzoyl-ATP (BzATP). Using calcium imaging in intact mice to survey a large number of DRG neurons and SGCs, we examined how intra-ganglionic purinergic signaling initiated by BzATP affects neuronal activities in vivo. We developed GFAP-GCaMP6s and Pirt-GCaMP6s mice to express the genetically encoded calcium indicator GGCaM6s in SGCs and DRG neurons, respectively. The application of BzATP to the ganglion induced concentration-dependent activation of SGCs in GFAP-GCaMP6s mice. In Pirt-GCaMP6s mice, BzATP initially activated more large-size neurons than small-size ones. Both glial and neuronal responses to BzATP were blocked by A438079, a P2X7R-selective antagonist. Moreover, blockers to pannexin1 channels (probenecid) and P2X3R (A317491) also reduced the actions of BzATP, suggesting that P2X7R stimulation may induce the opening of pannexin1 channels, leading to paracrine ATP release, which could further excite neurons by acting on P2X3Rs. Importantly, BzATP increased the responses of small-size DRG neurons and wide-dynamic range spinal neurons to subsequent peripheral stimuli. Our findings suggest that intra-ganglionic purinergic signaling initiated by P2X7R activation could trigger SGC-neuron interaction in vivo and increase DRG neuron excitability.
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11
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Stress-induced analgesia: an evaluation of effects on temporal summation of pain and the role of endogenous opioid mechanisms. Pain Rep 2022; 7:e987. [PMID: 35155968 PMCID: PMC8826964 DOI: 10.1097/pr9.0000000000000987] [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] [Received: 06/04/2021] [Revised: 12/13/2021] [Accepted: 12/17/2021] [Indexed: 11/27/2022] Open
Abstract
Acute stress reduced the initial pain rating in a temporal summation protocol via nonopioid mechanisms but did not affect temporal summation slope, an indicator of central sensitization. Introduction: Objectives: Methods: Results: Conclusions:
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12
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Elshennawy M, Ouachikh O, Aissouni Y, Youssef S, Zaki SS, Durif F, Hafidi A. Behavioral, Cellular and Molecular Responses to Cold and Mechanical Stimuli in Rats with Bilateral Dopamine Depletion in the Mesencephalic Dopaminergic Neurons. Neuroscience 2021; 479:107-124. [PMID: 34748858 DOI: 10.1016/j.neuroscience.2021.10.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 10/21/2021] [Accepted: 10/26/2021] [Indexed: 01/10/2023]
Abstract
Pain is the major non-motor symptom in Parkinson's disease (PD). Preclinical studies have mostly investigated mechanical pain by considering the decrease in a nociceptive threshold. Only a few studies have focused on thermal pain in animal models of PD. Therefore, the goal of this study was to assess the thermal nociceptive behavior of rats subjected to 6-hydroxydopamine (6-OHDA) administration, which constitutes an animal model of PD. Thermal plate investigation demonstrated significant thermal sensitivity to cold temperatures of 10 °C and 15 °C, and not to higher temperatures, in 6-OHDA-lesioned rats when compared with sham. 6-OHDA-lesioned rats also showed cold allodynia as demonstrated by a significant difference in the number of flinches, latency and reaction time to acetone stimulus. Ropinirole administration, a dopamine receptor 2 (D2R) agonist, blocked the acetone-induced cold allodynia in 6-OHDA-lesioned rats. In addition, mechanical hypersensitivity and static allodynia, as demonstrated by a significant difference in the vocalization threshold and pain score respectively, were noticed in 6-OHDA-lesioned rats. Acetone stimulus induced a significant increase in extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) phosphorylation, a pain process molecular marker, in the spinal dorsal horn (SDH), the insular and cingulate cortices in 6-OHDA-lesioned rats when compared to sham. In 6-OHDA-lesioned rats, there was a significant augmentation in the expression of both protein kinase C gamma (PKCγ) and glutamate decarboxylase 67 (GAD67) in the SDH. This highlighted an increase in excitation and a decrease in inhibition in the SDH. Overall, the present study demonstrated a clear cold thermal hypersensitivity, in addition to a mechanical one, in 6-OHDA-lesioned rats.
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Affiliation(s)
- Mennatallah Elshennawy
- Anatomy and Embryology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt; Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Omar Ouachikh
- Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Youssef Aissouni
- Université Clermont Auvergne, INSERM, NeuroDol U1107, 63000 Clermont-Ferrand, France.
| | - Shahira Youssef
- Anatomy and Embryology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
| | - Shahira S Zaki
- Anatomy and Embryology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
| | - Franck Durif
- Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
| | - Aziz Hafidi
- Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, 63000 Clermont-Ferrand, France.
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13
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Chao D, Mecca CM, Yu G, Segel I, Gold MS, Hogan QH, Pan B. Dorsal root ganglion stimulation of injured sensory neurons in rats rapidly eliminates their spontaneous activity and relieves spontaneous pain. Pain 2021; 162:2917-2932. [PMID: 33990112 PMCID: PMC8486885 DOI: 10.1097/j.pain.0000000000002284] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 03/23/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Dorsal root ganglion field stimulation (GFS) relieves evoked and spontaneous neuropathic pain by use-dependent blockade of impulse trains through the sensory neuron T-junction, which becomes complete within less than 1 minute for C-type units, also with partial blockade of Aδ units. We used this tool in the spinal nerve ligation (SNL) rat model to selectively block sensory neuron spontaneous activity (SA) of axotomized neurons at the fifth lumbar (L5) level vs blockade of units at the L4 level that remain uninjured but exposed to inflammation. In vivo dorsal root single-unit recordings after SNL showed increased SA in L5 units but not L4 units. Ganglion field stimulation blocked this SA. Ganglion field stimulation delivered at the L5 dorsal root ganglion blocked mechanical hyperalgesia behavior, mechanical allodynia, and ongoing spontaneous pain indicated by conditioned place preference, whereas GFS at L4 blocked evoked pain behavior but not spontaneous pain. In vivo single-unit recordings of spinal cord dorsal horn (DH) wide-dynamic-range neurons showed elevated SA after SNL, which was reduced by GFS at the L5 level but not by GFS at the L4 level. In addition, L5 GFS, but not L4 GFS, increased mechanical threshold of DH units during cutaneous mechanical stimulation, while L5 GFS exceeded L4 GFS in reducing evoked firing rates. Our results indicate that SA in injured neurons supports increased firing of DH wide-dynamic-range neurons, contributing to hyperalgesia, allodynia, and ongoing pain. Ganglion field stimulation analgesic effects after nerve injury are at least partly attributable to blocking propagation of this SA.
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Affiliation(s)
- Dongman Chao
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Christina M. Mecca
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Guoliang Yu
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Ian Segel
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Michael S. Gold
- Department of Neurobiology, University of Pittsburgh, 3500 Terrace Street Rm E1440 BST, Pittsburgh, PA 15213
| | - Quinn H. Hogan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
| | - Bin Pan
- Department of Anesthesiology, Medical College of Wisconsin, 8701 W Watertown Plank Rd, Milwaukee, WI 53226
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14
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Palsson TS, Doménech-García V, Boudreau SS, Graven-Nielsen T. Pain referral area is reduced by remote pain. Eur J Pain 2021; 25:1804-1814. [PMID: 33987881 DOI: 10.1002/ejp.1792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 05/02/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Endogenous pain inhibitory mechanisms are known to reduce pain intensity, but whether they influence the size and distribution of pain referral is unclear. This study aimed to determine if referred pain is reduced by applying a remote, conditioning painful stimulus. METHODS Twenty-four healthy men participated in this randomized, crossover study with a control and conditioning session. Referred pain was induced from the infraspinatus muscle (dominant side) by a painful pressure for 60 s. When applying pressure, the intensity was adjusted to a local pain intensity of 7/10 on a numerical rating scale. In the conditioning session, tonic painful pressure was simultaneously applied to the non-dominant leg during induction of referred pain. The area of referred pain was drawn onto a digital body chart and size extracted for data analysis. RESULTS For the total group and in a subgroup with distinct patterns of referred pain (n = 15/24), the pain area perceived in the back and front+back was smaller during the conditioning compared with the control (p < 0.05). No significant difference was found between sessions in a subgroup only demonstrating local pain (n = 9/24). CONCLUSIONS Engaging the descending noxious inhibitory control reduced the size of pain areas predominately when distinct pain referral was present. Assuming a conditioning effect of descending inhibitory control acting on dorsal horn neurons, these findings may indicate that mechanisms underlying pain referral can be modulated by endogenous control. The findings may indicate that referred pain may be a useful proxy to evaluate sensitivity of central pain mechanisms as previously suggested. SIGNIFICANCE The current results indicate a link between endogenous inhibition and pain referral. Descending inhibitory control effects on pain referral support a spinal mechanism involved in pain referral. Future studies should investigate whether the spatial characteristics of referred pain (e.g. size, frequency of affected body regions and distribution away from the primary nociceptive stimulus) can useful to evaluate the efficiency of endogenous pain modulation.
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Affiliation(s)
- Thorvaldur S Palsson
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Victor Doménech-García
- Department of Physiotherapy, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Zaragoza, Spain
| | - Shellie S Boudreau
- Center For Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Thomas Graven-Nielsen
- Center For Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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15
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Sculpting Dendritic Spines during Initiation and Maintenance of Neuropathic Pain. J Neurosci 2021; 40:7578-7589. [PMID: 32998955 DOI: 10.1523/jneurosci.1664-20.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/31/2020] [Accepted: 08/21/2020] [Indexed: 12/21/2022] Open
Abstract
Accumulating evidence has established a firm role for synaptic plasticity in the pathogenesis of neuropathic pain. Recent advances have highlighted the importance of dendritic spine remodeling in driving synaptic plasticity within the CNS. Identifying the molecular players underlying neuropathic pain induced structural and functional maladaptation is therefore critical to understanding its pathophysiology. This process of dynamic reorganization happens in unique phases that have diverse pathologic underpinnings in the initiation and maintenance of neuropathic pain. Recent evidence suggests that pharmacological targeting of specific proteins during distinct phases of neuropathic pain development produces enhanced antinociception. These findings outline a potential new paradigm for targeted treatment and the development of novel therapies for neuropathic pain. We present a concise review of the role of dendritic spines in neuropathic pain and outline the potential for modulation of spine dynamics by targeting two proteins, srGAP3 and Rac1, critically involved in the regulation of the actin cytoskeleton.
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16
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Duan W, Huang Q, Yang F, He SQ, Guan Y. Spinal Cord Stimulation Attenuates Below-Level Mechanical Hypersensitivity in Rats After Thoracic Spinal Cord Injury. Neuromodulation 2021; 24:33-42. [PMID: 32770848 PMCID: PMC7855640 DOI: 10.1111/ner.13248] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The burden of pain after spinal cord injury (SCI), which may occur above, at, or below injury level, is high worldwide. Spinal cord stimulation (SCS) is an important neuromodulation pain therapy, but its efficacy in SCI pain remains unclear. In SCI rats, we tested whether conventional SCS (50 Hz, 80% motor threshold [MoT]) and 1200 Hz, low-intensity SCS (40% MoT) inhibit hind paw mechanical hypersensitivity, and whether conventional SCS attenuates evoked responses of wide-dynamic range (WDR) neurons in lumbar spinal cord. MATERIALS AND METHODS Male rats underwent a moderate contusive injury at the T9 vertebral level. Six to eight weeks later, SCS or sham stimulation (120 min, n = 10) was delivered through epidural miniature electrodes placed at upper-lumbar spinal cord, with using a crossover design. Mechanical hypersensitivity was examined in awake rats by measuring paw withdrawal threshold (PWT) to stimulation with von Frey filaments. WDR neurons were recorded with in vivo electrophysiologic methods in a separate study of anesthetized rats. RESULTS Both conventional SCS and 1200 Hz SCS increased PWTs from prestimulation level in SCI rats, but the effects were modest and short-lived. Sham SCS was not effective. Conventional SCS (10 min) at an intensity that evokes the peak Aα/β waveform of sciatic compound action potential did not inhibit WDR neuronal responses (n = 19) to graded or repeated electrical stimulation that induces windup. CONCLUSIONS Conventional SCS and 1200 Hz, low-intensity SCS modestly attenuated below-level mechanical hypersensitivity after SCI. Inhibition of WDR neurons was not associated with pain inhibition from conventional SCS.
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Affiliation(s)
- Wanru Duan
- Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qian Huang
- Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine,
Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurological Surgery, Johns Hopkins
University, School of Medicine, Baltimore, Maryland, 21205, USA
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17
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Lassen J, Baron R. [Rheumatic diseases and neuropathic pain : Diagnosis and treatment]. Z Rheumatol 2020; 80:226-233. [PMID: 33355701 DOI: 10.1007/s00393-020-00950-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2020] [Indexed: 11/29/2022]
Abstract
Pain is a leading symptom in inflammatory rheumatic diseases. For a long time it has been assumed that this pain is of nociceptive origin; however, in about one fifth of all patients the pain remains despite successful anti-inflammatory treatment and is not typically described as nociceptive by those affected. Recent studies indicate that some patients with rheumatoid arthritis (RA) experience pain with a neuropathic pain component. The treatment of neuropathic pain with damage to the somatosensory system differs markedly from the treatment of nociceptive pain in which the pain processing system is intact. Thus, the recognition and, above all, the more precise differentiation of the pain symptoms of affected patients make a decisive contribution to a successful treatment. With the help of a few points in the history and a physical examination, the assumption of the diagnosis neuropathic pain can often be rejected or substantiated. Pain with a neuropathic component does not adequately respond to typical analgesics. Instead, the high efficacy of co-analgesics, such as anticonvulsants and antidepressants, has been repeatedly proven.
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Affiliation(s)
- J Lassen
- Sektion Neurologische Schmerzforschung und -therapie, Klinik für Neurologie, Christian-Albrechts-Universität zu Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Deutschland
| | - R Baron
- Sektion Neurologische Schmerzforschung und -therapie, Klinik für Neurologie, Christian-Albrechts-Universität zu Kiel, Arnold-Heller-Str. 3, Haus D, 24105, Kiel, Deutschland.
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18
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Arribas-Romano A, Fernández-Carnero J, Molina-Rueda F, Angulo-Diaz-Parreño S, Navarro-Santana MJ. Efficacy of Physical Therapy on Nociceptive Pain Processing Alterations in Patients with Chronic Musculoskeletal Pain: A Systematic Review and Meta-analysis. PAIN MEDICINE (MALDEN, MASS.) 2020; 21:2502-2517. [PMID: 32100027 DOI: 10.1093/pm/pnz366] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
INTRODUCTION Chronic musculoskeletal pain is a major health, social, and economic problem. Most of the subjects who suffer from chronic musculoskeletal pain present processes of central sensitization. Temporal summation and conditioned pain modulation are the two most commonly used clinical measures of this. The objective of this review is to evaluate the effects of physical therapy on temporal summation (TS) and conditioned pain modulation (CPM) in patients with chronic musculoskeletal pain. METHODS This is a systematic review and meta-analysis. We searched the MEDLINE, EMBASE, CINAHL, EBSCO, PubMed, PEDro, Cochrane Collaboration Trials Register, Cochrane Database of Systematic Reviews, and SCOPUS databases. Different mesh terms and key words were combined for the search strategy, with the aim of encompassing all studies that have used any type of physical therapy treatment in patients with chronic musculoskeletal pain and have measured both TS and CPM. RESULTS Eighteen studies remained for qualitative analysis and 16 for quantitative analysis. Statistically significant differences with a 95% confidence interval (CI) were obtained for TS (-0.21, 95% CI = -0.39 to -0.03, Z = 2.50, P = 0.02, N = 721) and CPM (0.34, 95% CI = 0.12 to 0.56, Z = 2.99, P = 0.003, N = 680) in favor of physical therapy as compared with control. Manual therapy produces a slight improvement in TS, and physical therapy modalities in general improve CPM. No significant differences between the subgroups of the meta-analysis were found. The methodological quality of the studies was high. CONCLUSIONS Physical therapy produces a slight improvement in central sensitization (CS)-related variables, with TS decreased and CPM increased when compared with a control group in patients with CMP. Only significant differences in TS were identified in the manual therapy subgroup.
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Affiliation(s)
- Alberto Arribas-Romano
- Escuela Internacional de Doctorado, Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Universidad Rey Juan Carlos, Alcorcón, Spain
- Physiotherapy and Pain Research Center. General Foundation of the University of Alcalá, Madrid, Spain
| | - Josué Fernández-Carnero
- Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Rey Juan Carlos University, Madrid, Spain
- La Paz Hospital Institute for Health Research, IdiPAZ, Madrid, Spain
- Grupo Multidisciplinar de Investigación & Tratamiento del Dolor, Grupo de Excelencia Investigadora URJC-Banco de Santander, Madrid, Spain
- Motion in Brains Research Group, Institute of Neuroscience and Movement Sciences (INCIMOV), Centro Superior de Estudios Universitarios La Salle, Universidad Autonoma de Madrid, Madrid, Spain
| | - Francisco Molina-Rueda
- Department of Physical Therapy, Occupational Therapy, Rehabilitation and Physical Medicine, Rey Juan Carlos University, Madrid, Spain
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19
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Chapman KB, Groenen PS, Vissers KC, van Helmond N, Stanton-Hicks MD. The Pathways and Processes Underlying Spinal Transmission of Low Back Pain: Observations From Dorsal Root Ganglion Stimulation Treatment. Neuromodulation 2020; 24:610-621. [PMID: 32329155 DOI: 10.1111/ner.13150] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/02/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Dorsal root ganglion stimulation (DRG-S) is a novel approach to treat chronic pain. Lead placement at L2 has been reported to be an effective treatment for axial low back pain (LBP) primarily of discogenic etiology. We have recently shown, in a diverse cohort including cases of multilevel instrumentation following extensive prior back surgeries, that DRG-S lead placement at T12 is another promising target. Local effects at the T12 DRG, alone, are insufficient to explain these results. MATERIALS AND METHODS We performed a literature review to explore the mechanisms of LBP relief with T12 DRG-S. FINDINGS Branches of individual spinal nerve roots innervate facet joints and posterior spinal structures, while the discs and anterior vertebrae are carried via L2, and converge in the dorsal horn (DH) of the spinal cord at T8-T9. The T12 nerve root contains cutaneous afferents from the low back and enters the DH of the spinal cord at T10. Low back Aδ and C-fibers then ascend via Lissauer's tract (LT) to T8-T9, converging with other low back afferents. DRG-S at T12, then, results in inhibition of the converged low back fibers via endorphin-mediated and GABAergic frequency-dependent mechanisms. Therefore, T12 lead placement may be the optimal location for DRG-S to treat LBP.
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Affiliation(s)
- Kenneth B Chapman
- The Spine & Pain Institute of New York, New York City, NY, USA.,Department of Anesthesiology, New York University Langone Medical Center, New York City, NY, USA.,Northwell Health Systems, New York City, NY, USA
| | - Pauline S Groenen
- The Spine & Pain Institute of New York, New York City, NY, USA.,College of Medicine, Radboud University, Nijmegen, the Netherlands
| | - Kris C Vissers
- Department of Anesthesiology, Pain, and Palliative Medicine, Radboud University, Nijmegen, the Netherlands
| | - Noud van Helmond
- The Spine & Pain Institute of New York, New York City, NY, USA.,Department of Anesthesiology, Cooper Medical School of Rowan University, Cooper University Hospital, Camden, NJ, USA
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20
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Tiwari V, He SQ, Huang Q, Liang L, Yang F, Chen Z, Tiwari V, Fujita W, Devi LA, Dong X, Guan Y, Raja SN. Activation of µ-δ opioid receptor heteromers inhibits neuropathic pain behavior in rodents. Pain 2020; 161:842-855. [PMID: 31815916 PMCID: PMC7085422 DOI: 10.1097/j.pain.0000000000001768] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Several reports support the idea that µ- and δ-opioid receptors (ORs) may exist as heterodimers in brain regions involved in pain signaling. The unique pharmacology of these heteromers may present a novel analgesic target. However, the role of µ-δ heteromers in sensory neurons involved in pain and opioid analgesia remains unclear, particularly during neuropathic pain. We examined the effects of spinal nerve injury on µ-δ heteromer expression in dorsal root ganglion (DRG) neurons and the effects of a µ-δ heteromer-targeting agonist, CYM51010, on neuropathic pain behavior in rats and mice. An L5 spinal nerve ligation (SNL) in rats significantly decreased µ-δ heteromer expression in L5 DRG but increased heteromer levels in uninjured L4 DRG. Importantly, in SNL rats, subcutaneous injection of CYM51010 inhibited mechanical hypersensitivity in a dose-related manner (EC50: 1.09 mg/kg) and also reversed heat hyperalgesia and attenuated ongoing pain (2 mg/kg, subcutaneously). HEK-293T cell surface-labeled with µ- and δ-ORs internalized both receptors after exposure to CYM51010. By contrast, in cells transfected with µ-OR alone, CYM51010 was significantly less effective at inducing receptor internalization. Electrophysiologic studies showed that CYM51010 inhibited the C-component and windup phenomenon in spinal wide dynamic range neurons of SNL rats. The pain inhibitory effects of CYM51010 persisted in morphine-tolerant rats but was markedly attenuated in µ-OR knockout mice. Our studies show that spinal nerve injury may increase µ-δ heterodimerization in uninjured DRG neurons, and that µ-δ heteromers may be a potential therapeutic target for relieving neuropathic pain, even under conditions of morphine tolerance.
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Affiliation(s)
- Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qian Huang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Lingli Liang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Vineeta Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Wakako Fujita
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Lakshmi A. Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Howard Hughes Medical Institute, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurological Surgery, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
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21
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Defrin R, Cohen Sagy N, Biran I, Goor-Aryeh I, Shai R, Ginzburg K. Enhanced pain modulation capacity among individuals with borderline personality disorder: A possible mechanism underlying their hypoalgesia. Eur J Pain 2019; 24:544-554. [PMID: 31702076 DOI: 10.1002/ejp.1504] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/30/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Ample evidence suggests that individuals with borderline personality disorder (BPD) exhibit hyposensitivity to pain. Since the underlying mechanism of the pain hyposensitivity is unknown, we tested here for the first time whether this hyposensitivity is pain specific or exists also for innocuous sensation, and whether it is associated with enhanced descending pain modulation capabilities. METHODS Participants were 55 women; 22 patients with BPD and 33 matched healthy controls. Testing included the measurement of warmth sensation threshold (WST), heat-pain threshold (HPT), pain adaptation, conditioned pain modulation (CPM) and temporal summation of heat-pain (TSP). The level of dissociation was also evaluated. RESULTS Women with BPD had higher WST and HPT compared with healthy controls. Moreover, women with BPD had greater magnitude of pain adaptation and CPM as well as higher dissociation level compared to controls. In neither the BPD nor the control group did WST and HPT correlate with pain adaptation, CPM or dissociation. In the BPD group only, HPT inversely correlated with the magnitude of TSP. CONCLUSIONS Women with BPD present generalized hyposensitivity to both innocuous and noxious stimuli. Furthermore, women with BPD exhibit more efficient pain inhibition capabilities than healthy controls. While efficient pain modulation may underlie pain hyposensitivity in BPD, both traits may exist independently from each other, or may be moderated by another factor such as dissociation. SIGNIFICANCE On the basis of testing pronociceptive and antinociceptive components among individuals with BPD and healthy controls, this study reveals enhanced ability to inhibit pain among woman with borderline personality disorder (BPD) which may underlie hyposensitivity to both noxious and innocuous stimuli and perhaps also self-injurious behaviour among these individuals. The study contributes novel information on possible mechanisms involved in BPD manifestations.
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Affiliation(s)
- Ruth Defrin
- Department of Physical Therapy, School of Allied Health Professions, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neurosciences, Tel Aviv University, Tel Aviv, Israel
| | - Nitzan Cohen Sagy
- School of Psychological Sciences, Gershon H. Gordon Faculty of Social Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Iftah Biran
- Division of Psychiatry, Sheba Medical Center, Ramat-Gan, and The Department of Neurology, Neurological Institute, Tel Aviv Medical Center, Tel Aviv, Israel
| | - Itay Goor-Aryeh
- Pain Management Center, Department of Anesthesiology and Intensive Care, Sheba Medical Center, Tel Hashomer, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Roni Shai
- The Bob Shapell School of Social Work, Tel Aviv University, Tel Aviv, Israel
| | - Karni Ginzburg
- The Bob Shapell School of Social Work, Tel Aviv University, Tel Aviv, Israel
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22
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Caylor J, Reddy R, Yin S, Cui C, Huang M, Huang C, Rao R, Baker DG, Simmons A, Souza D, Narouze S, Vallejo R, Lerman I. Spinal cord stimulation in chronic pain: evidence and theory for mechanisms of action. Bioelectron Med 2019; 5:12. [PMID: 31435499 PMCID: PMC6703564 DOI: 10.1186/s42234-019-0023-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 05/30/2019] [Indexed: 12/30/2022] Open
Abstract
Well-established in the field of bioelectronic medicine, Spinal Cord Stimulation (SCS) offers an implantable, non-pharmacologic treatment for patients with intractable chronic pain conditions. Chronic pain is a widely heterogenous syndrome with regard to both pathophysiology and the resultant phenotype. Despite advances in our understanding of SCS-mediated antinociception, there still exists limited evidence clarifying the pathways recruited when patterned electric pulses are applied to the epidural space. The rapid clinical implementation of novel SCS methods including burst, high frequency and dorsal root ganglion SCS has provided the clinician with multiple options to treat refractory chronic pain. While compelling evidence for safety and efficacy exists in support of these novel paradigms, our understanding of their mechanisms of action (MOA) dramatically lags behind clinical data. In this review, we reconstruct the available basic science and clinical literature that offers support for mechanisms of both paresthesia spinal cord stimulation (P-SCS) and paresthesia-free spinal cord stimulation (PF-SCS). While P-SCS has been heavily examined since its inception, PF-SCS paradigms have recently been clinically approved with the support of limited preclinical research. Thus, wide knowledge gaps exist between their clinical efficacy and MOA. To close this gap, many rich investigative avenues for both P-SCS and PF-SCS are underway, which will further open the door for paradigm optimization, adjunctive therapies and new indications for SCS. As our understanding of these mechanisms evolves, clinicians will be empowered with the possibility of improving patient care using SCS to selectively target specific pathophysiological processes in chronic pain.
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Affiliation(s)
- Jacob Caylor
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Rajiv Reddy
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Sopyda Yin
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Christina Cui
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Mingxiong Huang
- Department of Radiology, University of California San Diego School of Medicine, La Jolla, CA USA
- Department of Radiology, VA San Diego Healthcare System, La Jolla, CA USA
| | - Charles Huang
- Department of Radiology, VA San Diego Healthcare System, La Jolla, CA USA
- Department of Bioengineering, Stanford University, Palo Alto, CA USA
| | - Ramesh Rao
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA USA
| | - Dewleen G. Baker
- VA Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA USA
- Department of Psychiatry, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Alan Simmons
- VA Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA USA
- Department of Psychiatry, University of California San Diego School of Medicine, La Jolla, CA USA
| | - Dmitri Souza
- Center for Pain Medicine, Western Reserve Hospital. Department of Surgery, Northeast Ohio Medical School (NEOMED), Athens, OH USA
| | - Samer Narouze
- Center for Pain Medicine, Western Reserve Hospital. Department of Surgery, Northeast Ohio Medical School (NEOMED), Athens, OH USA
| | - Ricardo Vallejo
- Basic Science Research, Millennium Pain Center, Bloomington, IL USA
- School of Biological Sciences, Illinois State University, Normal, IL USA
- Department of Psychology, Illinois Wesleyan University, Bloomington, IL USA
| | - Imanuel Lerman
- Department of Anesthesiology, Center for Pain Medicine, University of California San Diego School of Medicine, La Jolla, CA USA
- VA Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System, La Jolla, CA USA
- Department of Radiology, VA San Diego Healthcare System, La Jolla, CA USA
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA USA
- Present Address: VA San Diego, 3350 La Jolla Village Dr, (MC116A), San Diego, CA 92161 USA
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Comparison of masseter muscle referred sensations after mechanical and glutamate stimulation: a randomized, double-blind, controlled, cross-over study. Pain 2019; 159:2649-2657. [PMID: 30180087 DOI: 10.1097/j.pain.0000000000001379] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Referred sensations (RS) are commonly found in various musculoskeletal pain conditions. Experimental studies have shown that RS can be elicited through glutamate injection and mechanical stimulation. Despite this, differences and similarities between these modalities in RS outcomes remain unclear. The aim of this study was to assess differences between mechanical-induced and glutamate injection-induced RS in the trigeminal region. The present randomized, double-blind, controlled, cross-over study recruited 60 healthy participants who were assessed in 2 different sessions. In both sessions, pressure was applied to the masseter muscle with 4 different forces (0.5, 1, 2, and 4 kg), and glutamate (1 mol/L or 0.25 mol/L) was injected into the same area. Participants rated their perceived masseter sensations and rated and drew any RS they experienced. No difference was found in number of participants reporting RS after glutamate injection compared with mechanical stimulation. More participants reported RS when the stimulus was painful compared with a nonpainful stimulus. Furthermore, it was shown that the more intense the stimulus, the higher the frequency of RS. Finally, RS centre-of-gravity location was similar between the 2 sessions. In summary, RS was elicited in healthy individuals through both modalities, and no differences in frequency of RS were observed in the orofacial region. Hence, RS does not seem to be modality-dependent, and only the painfulness of the stimulus caused an increase in frequency of RS. Finally, RS location for each participant was similar in both sessions possibly indicating a preferred location of referral. These findings may have implications for our understanding of RS in craniofacial pain conditions.
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Coelho M, Ela N, Garvin A, Cox C, Sloan W, Palaima M, Cleland JA. The effectiveness of manipulation and mobilization on pain and disability in individuals with cervicogenic and tension-type headaches: a systematic review and meta-analysis. PHYSICAL THERAPY REVIEWS 2019. [DOI: 10.1080/10833196.2019.1572963] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Matthew Coelho
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Naomi Ela
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Allison Garvin
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Charles Cox
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Wendy Sloan
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Mary Palaima
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
| | - Joshua A. Cleland
- Physical Therapy Department, Franklin Pierce University, Manchester, NH, USA
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Kuhlmann L, Olesen SS, Olesen AE, Arendt-Nielsen L, Drewes AM. Mechanism-based pain management in chronic pancreatitis - is it time for a paradigm shift? Expert Rev Clin Pharmacol 2019; 12:249-258. [PMID: 30664364 DOI: 10.1080/17512433.2019.1571409] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Pain is the most common symptom in chronic pancreatitis and treatment remains a challenge. Management of visceral pain, in general, is only sparsely documented, and treatment in the clinic is typically based on empirical knowledge from somatic pain conditions. This may be problematic, as many aspects of the neurobiology differ significantly from somatic pain, and organs such as the gut and liver play a major role in tolerability to analgesics. On the other hand, clinical awareness and new methods for quantitative assessment of pain mechanisms, will likely increase our understanding of the visceral pain system and guide more individualized pain management. Areas covered: This review includes an overview of known pain mechanisms in chronic pancreatitis and how to characterize them using quantitative sensory testing. The aim is to provide a mechanism-oriented approach to analgesic treatment, including treatment of psychological factors affecting pain perception and consideration of side effects in the management plan. Expert opinion: A mechanism-based examination and profiling of pain in chronic pancreatitis will enable investigators to provide a well-substantiated approach to effective management. This mechanism-based, individualized regime will pave the road to better pain relief and spare the patient from unnecessary trial-and-error approaches and unwanted side effects.
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Affiliation(s)
- Louise Kuhlmann
- a Centre for Pancreatic Diseases and Mech-Sense, Department of Gastroenterology and Hepatology , Aalborg University Hospital , Aalborg , Denmark.,b Department of Internal Medicine , North Denmark Regional Hospital , Hjørring , Denmark.,c Department of Clinical Medicine , Aalborg University , Aalborg , Denmark
| | - Søren S Olesen
- a Centre for Pancreatic Diseases and Mech-Sense, Department of Gastroenterology and Hepatology , Aalborg University Hospital , Aalborg , Denmark.,c Department of Clinical Medicine , Aalborg University , Aalborg , Denmark
| | - Anne E Olesen
- a Centre for Pancreatic Diseases and Mech-Sense, Department of Gastroenterology and Hepatology , Aalborg University Hospital , Aalborg , Denmark.,c Department of Clinical Medicine , Aalborg University , Aalborg , Denmark
| | - Lars Arendt-Nielsen
- d Center for Sensory-Motor Interaction, School of Medicine , Aalborg University , Aalborg , Denmark
| | - Asbjørn M Drewes
- a Centre for Pancreatic Diseases and Mech-Sense, Department of Gastroenterology and Hepatology , Aalborg University Hospital , Aalborg , Denmark.,c Department of Clinical Medicine , Aalborg University , Aalborg , Denmark
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Hashimoto-Torii K, Sasaki M, Chang YW, Hwang H, Waxman SG, Kocsis JD, Rakic P, Torii M. Detection of local and remote cellular damage caused by spinal cord and peripheral nerve injury using a heat shock signaling reporter system. IBRO Rep 2018; 5:91-98. [PMID: 30480161 PMCID: PMC6240805 DOI: 10.1016/j.ibror.2018.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 11/05/2018] [Indexed: 12/14/2022] Open
Abstract
Spinal cord and peripheral nerve injury results in extensive damage to the locally injured cells as well as distant cells that are functionally connected to them. Both primary and secondary damage can cause a broad range of clinical abnormalities, including neuropathic pain and cognitive and memory dysfunction. However, the mechanisms underlying these abnormalities remain unclear, awaiting new methods to identify affected cells to enable examination of their molecular, cellular and physiological characteristics. Here, we report that both primary and secondary damage to cells in mouse models of spinal cord and peripheral nerve injury can be detected in vivo using a novel fluorescent reporter system based on the immediate stress response via activation of Heat Shock Factor 1. We also provide evidence for altered electrophysiological properties of reporter-positive secondarily-injured neurons. The comprehensive identification of injured, but surviving cells located both close and at distant locations from the injury site in vivo will provide a way to study their pathophysiology and possibly prevention of their further deterioration.
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Key Words
- Cellular damage
- DRG, dorsal root ganglion
- FG, Fluoro-Gold
- HRP, horseradish peroxidase
- HSE, heat shock-response element
- HSF1, heat shock factor 1
- HSP, heat shock protein
- Heat shock signaling
- IL-6, interleukin 6
- M1, primary motor cortex
- M2, secondary motor cortex
- MPtA, medial parietal association cortex
- PBS, phosphate buffered saline
- PCR, polymerase chain reaction
- RFP, red fluorescent protein
- Reporter mouse
- SCI, spinal cord injury
- SNI, sciatic nerve injury
- Sciatic nerve injury
- Spinal cord injury
- WDR, wide-dynamic range
- WGA, wheat germ agglutinin
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Affiliation(s)
- Kazue Hashimoto-Torii
- Center for Neuroscience Research, Children’s Research Institute, Children’s National Medical Center, Washington, DC 20010, USA
- Department of Pediatrics, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20052, USA
- Department of Neurobiology and Kavli Institute for Neuroscience, School of Medicine, Yale University, New Haven, CT 06510, USA
| | - Masanori Sasaki
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, 06510, USA
- Center for Neuroscience and Regeneration Research, VA Connecticut Healthcare System, West Haven, Connecticut, 06516, USA
- Department of Neural Regenerative Medicine, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, 060-8556, Japan
| | - Yu-Wen Chang
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, 06510, USA
- Center for Neuroscience and Regeneration Research, VA Connecticut Healthcare System, West Haven, Connecticut, 06516, USA
| | - Hye Hwang
- Center for Neuroscience Research, Children’s Research Institute, Children’s National Medical Center, Washington, DC 20010, USA
- Institute of Biomedical Sciences, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20052, USA
| | - Stephen G. Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, 06510, USA
- Center for Neuroscience and Regeneration Research, VA Connecticut Healthcare System, West Haven, Connecticut, 06516, USA
| | - Jeffery D. Kocsis
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, 06510, USA
- Center for Neuroscience and Regeneration Research, VA Connecticut Healthcare System, West Haven, Connecticut, 06516, USA
| | - Pasko Rakic
- Department of Neurobiology and Kavli Institute for Neuroscience, School of Medicine, Yale University, New Haven, CT 06510, USA
| | - Masaaki Torii
- Center for Neuroscience Research, Children’s Research Institute, Children’s National Medical Center, Washington, DC 20010, USA
- Department of Pediatrics, School of Medicine and Health Sciences, The George Washington University, Washington, DC 20052, USA
- Department of Neurobiology and Kavli Institute for Neuroscience, School of Medicine, Yale University, New Haven, CT 06510, USA
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Brain Dynamics and Temporal Summation of Pain Predicts Neuropathic Pain Relief from Ketamine Infusion. Anesthesiology 2018; 129:1015-1024. [DOI: 10.1097/aln.0000000000002417] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Editor’s Perspective
What We Already Know about This Topic
What This Article Tells Us That Is New
Background
Ketamine is an N-methyl-d-aspartate receptor antagonist that reduces temporal summation of pain and modulates antinociception. Ketamine infusions can produce significant relief of neuropathic pain, but the treatment is resource intensive and can be associated with adverse effects. Thus, it is crucial to select patients who might benefit from this treatment. The authors tested the hypothesis that patients with enhanced temporal summation of pain and the capacity to modulate pain via the descending antinociceptive brain pathway are predisposed to obtain pain relief from ketamine.
Methods
Patients with refractory neuropathic pain (n = 30) and healthy controls underwent quantitative sensory testing and resting-state functional magnetic resonance imaging and then completed validated questionnaires. Patients then received outpatient intravenous ketamine (0.5 to 2 mg · kg−1 · h−1; mean dose 1.1 mg · kg−1 · h−1) for 6 h/day for 5 consecutive days. Pain was assessed 1 month later. Treatment response was defined as greater than or equal to 30% pain relief (i.e., reduction in pain scores). We determined the relationship between our primary outcome measure of pain relief with pretreatment temporal summation of pain and with brain imaging measures of dynamic functional connectivity between the default mode network and the descending antinociceptive brain pathway.
Results
Approximately 50% of patients achieved pain relief (mean ± SD; Responders, 61 ± 35%; Nonresponders, 7 ± 14%). Pretreatment temporal summation was associated with the effect of ketamine (ρ = −0.52, P = 0.003) and was significantly higher in Responders (median [25th, 75th] = 200 [100, 345]) compared with Nonresponders (44 [9, 92]; P = 0.001). Pretreatment dynamic connectivity was also associated with the clinical effect of ketamine (ρ = 0.51, P = 0.004) and was significantly higher in Responders (mean ± SD, 0.55 ± 0.05) compared with Nonresponders (0.51 ± 0.03; P = 0.006). Finally, the dynamic engagement of the descending antinociceptive system significantly mediated the relationship between pretreatment pain facilitation and pain relief (95% CI, 0.005 to 0.065).
Conclusions
These findings suggest that brain and behavioral measures have the potential to prognosticate and develop ketamine-based personalized pain therapy.
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He SQ, Xu Q, Tiwari V, Yang F, Anderson M, Chen Z, Grenald SA, Raja SN, Dong X, Guan Y. Oligomerization of MrgC11 and μ-opioid receptors in sensory neurons enhances morphine analgesia. Sci Signal 2018; 11:eaao3134. [PMID: 29921657 PMCID: PMC6328051 DOI: 10.1126/scisignal.aao3134] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The μ-opioid receptor (MOR) agonist morphine is commonly used for pain management, but it has severe adverse effects and produces analgesic tolerance. Thus, alternative ways of stimulating MOR activity are needed. We found that MrgC11, a sensory neuron-specific G protein-coupled receptor, may form heteromeric complexes with MOR. Peptide-mediated activation of MrgC11 enhanced MOR recycling by inducing coendocytosis and sorting of MOR for membrane reinsertion. MrgC11 activation also inhibited the coupling of MOR to β-arrestin-2 and enhanced the morphine-dependent inhibition of cAMP production. Intrathecal coadministration of a low dose of an MrgC agonist potentiated acute morphine analgesia and reduced chronic morphine tolerance in wild-type mice but not in Mrg-cluster knockout (Mrg KO) mice. BAM22, a bivalent agonist of MrgC and opioid receptors, enhanced the interaction between MrgC11 and MOR and produced stronger analgesia than did the individual monovalent agonists. Morphine-induced neuronal and pain inhibition was reduced in Mrg KO mice compared to that in wild-type mice. Our results uncover MrgC11-MOR interactions that lead to positive functional modulation of MOR. MrgC shares genetic homogeneity and functional similarity with human MrgX1. Thus, harnessing this positive modulation of MOR function by Mrg signaling may enhance morphine analgesia in a sensory neuron-specific fashion to limit central side effects.
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Affiliation(s)
- Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qian Xu
- Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael Anderson
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shaness A Grenald
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xinzhong Dong
- Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Tiwari V, Anderson M, Yang F, Tiwari V, Pharm M, Zheng Q, He SQ, Zhang T, Shu B, Chen X, Grenald SA, Stephens KE, Chen Z, Dong X, Raja SN, Guan Y. Peripherally Acting μ-Opioid Receptor Agonists Attenuate Ongoing Pain-associated Behavior and Spontaneous Neuronal Activity after Nerve Injury in Rats. Anesthesiology 2018; 128:1220-1236. [PMID: 29601322 PMCID: PMC5953805 DOI: 10.1097/aln.0000000000002191] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Ongoing neuropathic pain is difficult to treat. The authors examined whether dermorphin [D-Arg2, Lys4] (1-4) amide, a peripherally acting µ-opioid receptor agonist, attenuates ongoing pain-associated manifestations after nerve injury in rats and mice. METHODS Using conditioned place preference assay, the authors tested whether animals show a preference to the environment associated with drug treatment. Wide-dynamic range and dorsal root ganglion neuronal activities were measured by electrophysiology recording and calcium imaging. RESULTS Nerve-injured animals stayed longer in dermorphin [D-Arg2, Lys4] (1-4) amide-paired chamber after conditioning than during preconditioning (rats: 402.4 ± 61.3 vs. 322.1 ± 45.0 s, 10 mg/kg, n = 9, P = 0.009; mice: 437.8 ± 59.4 vs. 351.3 ± 95.9 s, 2 mg/kg, n = 8, P = 0.047). Topical ganglionic application of dermorphin [D-Arg2, Lys4] (1-4) amide (5 μM, 1 μl, n = 5) reduced the numbers of small-diameter dorsal root ganglion neurons that showed spontaneous activity (1.1 ± 0.4 vs. 1.5 ± 0.3, P = 0.044) and that were activated by test stimulation (15.5 ± 5.5 vs. 28.2 ± 8.2, P = 0.009) after injury. In neuropathic rats, dermorphin [D-Arg2, Lys4] (1-4) amide (10 mg/kg, n = 8) decreased spontaneous firing rates in wide-dynamic range neurons to 53.2 ± 46.6% of predrug level, and methylnaltrexone (5 mg/kg, n = 9) blocked dermorphin [D-Arg2, Lys4] (1-4) amide-induced place preference and inhibition of wide-dynamic range neurons. Dermorphin [D-Arg2, Lys4] (1-4) amide increased paw withdrawal threshold (17.5 ± 2.2 g) from baseline (3.5 ± 0.7 g, 10 mg/kg, n = 8, P = 0.002) in nerve-injured rats, but the effect diminished after repeated administrations. CONCLUSIONS Peripherally acting μ-opioids may attenuate ongoing pain-related behavior and its neurophysiologic correlates. Yet, repeated administrations cause antiallodynic tolerance.
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Affiliation(s)
- Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER)-Ahmedabad, Gandhinagar, 382355, Gujarat, India
| | - Michael Anderson
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | | | - M. Pharm
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qin Zheng
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Tong Zhang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurology, Tiantan Hospital, Capital Medical University, Beijing, 100050, China
| | - Bin Shu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Wuhan, 430030, China
| | - Xueming Chen
- Department of Orthopedics, Luhe Hospital, Capital Medical University, Beijing, 100020, China
| | - Shaness A. Grenald
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Kimberly E. Stephens
- Department of Pharmacology and Molecular Sciences, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Center for Epigenetics, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
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Yang F, Anderson M, He S, Stephens K, Zheng Y, Chen Z, Raja SN, Aplin F, Guan Y, Fridman G. Differential expression of voltage-gated sodium channels in afferent neurons renders selective neural block by ionic direct current. SCIENCE ADVANCES 2018; 4:eaaq1438. [PMID: 29651458 PMCID: PMC5895440 DOI: 10.1126/sciadv.aaq1438] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 02/21/2018] [Indexed: 06/01/2023]
Abstract
The assertion that large-diameter nerve fibers have low thresholds and small-diameter fibers have high thresholds in response to electrical stimulation has been held in a nearly axiomatic regard in the field of neuromodulation and neuroprosthetics. In contrast to the short pulses used to evoke action potentials, long-duration ionic direct current has been shown to block neural activity. We propose that the main determinant of the neural sensitivity to direct current block is not the size of the axon but the types of voltage-gated sodium channels prevalent in its neural membrane. On the basis of the variants of voltage-gated sodium channels expressed in different types of neurons in the peripheral nerves, we hypothesized that the small-diameter nociceptive fibers could be preferentially blocked. We show the results of a computational model and in vivo neurophysiology experiments that offer experimental validation of this novel phenomenon.
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Affiliation(s)
- Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Neurobiology, Capital Medical University, Beijing 100069, PR China
| | - Michael Anderson
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Shaoqiu He
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kimberly Stephens
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Yu Zheng
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Felix Aplin
- Department of Neurological Surgery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Neurological Surgery, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Gene Fridman
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
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Abstract
Synopsis Manual therapy interventions are popular among individual health care providers and their patients; however, systematic reviews do not strongly support their effectiveness. Small treatment effect sizes of manual therapy interventions may result from a "one-size-fits-all" approach to treatment. Mechanistic-based treatment approaches to manual therapy offer an intriguing alternative for identifying patients likely to respond to manual therapy. However, the current lack of knowledge of the mechanisms through which manual therapy interventions inhibit pain limits such an approach. The nature of manual therapy interventions further confounds such an approach, as the related mechanisms are likely a complex interaction of factors related to the patient, the provider, and the environment in which the intervention occurs. Therefore, a model to guide both study design and the interpretation of findings is necessary. We have previously proposed a model suggesting that the mechanical force from a manual therapy intervention results in systemic neurophysiological responses leading to pain inhibition. In this clinical commentary, we provide a narrative appraisal of the model and recommendations to advance the study of manual therapy mechanisms. J Orthop Sports Phys Ther 2018;48(1):8-18. doi:10.2519/jospt.2018.7476.
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Dopamine D1-like Receptors Regulate Constitutive, μ-Opioid Receptor-Mediated Repression of Use-Dependent Synaptic Plasticity in Dorsal Horn Neurons: More Harm than Good? J Neurosci 2017; 36:5661-73. [PMID: 27194343 DOI: 10.1523/jneurosci.2469-15.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 04/11/2016] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED The current study reports on a synaptic mechanism through which D1-like receptors (D1LRs) modulate spinal nociception and plasticity by regulating activation of the μ-opioid receptor (MOR).D1LR stimulation with agonist SKF 38393 concentration-dependently depressed C-fiber-evoked potentials in rats receiving spinal nerve ligation (SNL), but not in uninjured rats. Depression was prevented by MOR- but not GABA-receptor blockade. Neurons expressing the D1 subtype were immunopositive for met-enkephalin and vesicular glutamate transporter VGLUT2, but not for GABAergic marker vGAT.Nerve ligation was followed by increased immunoreactivity for D1 in synaptic compartment (P3) in dorsal horn homogenates and presynaptic met-enkephalin-containing boutons. SNL led to increased immunoreactivity for met-enkephalin in dorsal horn homogenates, which was dose-dependently attenuated by selective D1LR antagonist SCH 23390. During blockade of either D1R or MOR, low-frequency (0.2 or 3 Hz) stimulation (LFS) to the sciatic nerve induced long-term potentiation (LTP) of C-fiber-evoked potentials, revealing a constituent role of both receptors in repressing afferent-induced synaptic plasticity. LFS consistently induced NMDA receptor-dependent LTP in nerve-injured rats. The ability of MOR both to prevent LTP and to modulate mechanical and thermal pain thresholds in behavioral tests was preserved in nerve-ligated rats that were postoperatively treated with SCH 23390. D1LR priming for 30 min sufficed to disrupt MOR function in otherwise naive rats via a mechanism involving receptor overuse.The current data support that, whereas D1LR-modulated MOR activation is instrumental in antinociception and endogenous repression of synaptic plasticity, this mechanism deteriorates rapidly by sustained use, generating increased vulnerability to afferent input. SIGNIFICANCE STATEMENT The current study shows that dopamine D1-like receptors (D1LRs) and μ-opioid receptors (MOR) in the spinal dorsal horn constitutively repress the expression of synaptic long-term potentiation (LTP) of C-fiber-evoked potentials. Anatomical data are provided supporting that the D1 subtype regulates MOR function by modulating met-enkephalin release. Sustained neuropathic pain induced by spinal nerve ligation is accompanied by D1R and met-enkephalin upregulation, acquired D1LR-mediated antinociception, and a loss of endogenous repression of further synaptic plasticity. We show that the ability of MOR to oppose LTP is rapidly impaired by sustained D1LR activation via a mechanism involving sustained MOR activation.
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Individual Differences in Temporal Summation of Pain Reflect Pronociceptive and Antinociceptive Brain Structure and Function. J Neurosci 2015; 35:9689-700. [PMID: 26134651 DOI: 10.1523/jneurosci.5039-14.2015] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Temporal summation of pain (TSP), the perception of increasingly greater pain evoked by repetitive noxious stimuli, is highly variable between individuals. Individuals with facilitated pain processing and/or reduced pain-modulatory capabilities are regarded as pronociceptive, whereas individuals with reduced pain processing capacity are characterized as antinociceptive. Brodmann area (BA) 3a of the primary somatosensory cortex is part of an ascending pathway from the sensory thalamus that mediates TSP. Descending pain modulation involves projections from the subgenual anterior cingulate cortex (sgACC) to the periaqueductal gray to the rostral ventromedial medulla (RVM). Here, we tested the hypothesis that pronociceptive individuals have an enhanced TSP response compared with antinociceptive individuals, marked by facilitated ascending nociceptive processing and/or reduced capacity for descending pain modulation. Eighty healthy humans were tested with a TSP protocol and underwent structural and resting-state functional magnetic resonance imaging. We found large interindividual differences in TSP responses, which were positively correlated with functional connectivity (FC) between individuals' right sensory thalamus with their BA 3a (thal-BA 3a), and with cortical thickness in their insula and medial prefrontal cortex. In contrast, TSP was negatively correlated with FC between individuals' RVM with their sgACC (RVM-sgACC). When subjects were grouped as pronociceptive or antinociceptive based on whether they had greater thal-BA 3a or RVM-sgACC FC respectively, pronociceptive subjects showed greater TSP responses. Furthermore, TSP was positively correlated with the extent of imbalance toward ascending nociceptive processing. Our study indicates that individuals with enhanced TSP have facilitated ascending nociceptive processing and reduced pain-modulatory capacities. SIGNIFICANCE STATEMENT This study provides novel evidence that an individual's propensity to experience amplified pain with repeated stimuli [i.e., temporal summation of pain (TSP)] reflects attributes of their "pain connectome," namely stronger ascending nociceptive and weaker descending pain-modulatory components. Understanding the individual neural mechanisms underlying TSP within individuals has implications for developing personalized pain-management strategies for chronic pain.
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Yang F, Zhang T, Tiwari V, Shu B, Zhang C, Wang Y, Vera-Portocarrero LP, Raja SN, Guan Y. Effects of Combined Electrical Stimulation of the Dorsal Column and Dorsal Roots on Wide-Dynamic-Range Neuronal Activity in Nerve-Injured Rats. Neuromodulation 2015; 18:592-7; discussion 598. [PMID: 26307526 DOI: 10.1111/ner.12341] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/04/2015] [Accepted: 07/08/2015] [Indexed: 01/10/2023]
Abstract
OBJECTIVES Electrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits. MATERIALS AND METHODS By conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 min) or alternate (5 min) pattern inhibits WDR neuronal activity better than CS at DC alone (5 min). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison. RESULTS At a moderate intensity of 50% (Ab0 + Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 msec) and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons. CONCLUSIONS These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons.
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Affiliation(s)
- Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tong Zhang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bin Shu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Chen Zhang
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Yun Wang
- Department of Anesthesiology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | | | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Strong Manual Acupuncture Manipulation Could Better Inhibit Spike Frequency of the Dorsal Horn Neurons in Rats with Acute Visceral Nociception. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:675437. [PMID: 26257816 PMCID: PMC4518182 DOI: 10.1155/2015/675437] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 12/12/2022]
Abstract
Afferent impulses from visceral nociception can be regulated by acupuncture at spinal cord level; however, the effects of different manual acupuncture (MA) manipulations on the afferent impulses are still unknown. Here, we analyzed the spike frequency of excitatory gastric-related wide dynamic range (WDR) neurons in spinal dorsal horn (SDH) following acute gastric distension (GD) in rats and compared their responses to MA manipulations with four different frequencies (0.5, 1, 2, and 3 Hz) at Zusanli (ST36). Results indicated that the spike frequency was increased by acute GD stimulation. Under acute GD circumstances, the spike frequency was further activated by weak MA stimulation (0.5 and 1 Hz), while being significantly inhibited by strong MA stimulation (2 and 3 Hz). After 10 minutes of the strong MA stimulation, same intensity of acute GD caused less spike frequency. Our previous researches had demonstrated that different MA manipulations could increase spike frequency in an intensity-dependent manner in normal rats; these findings suggest that acupuncture may have different modulatory effects depending on the state of the stomach. Since neuronal spike frequency was related to the level of nociception, the results suggest that strong MA manipulation may have better effect on acute visceral nociception.
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Injury-specific promoters enhance herpes simplex virus-mediated gene therapy for treating neuropathic pain in rodents. THE JOURNAL OF PAIN 2015; 16:283-90. [PMID: 25576797 DOI: 10.1016/j.jpain.2014.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 12/13/2014] [Accepted: 12/13/2014] [Indexed: 12/11/2022]
Abstract
UNLABELLED Chronic neuropathic pain is often difficult to treat with current pain medications. Gene therapy is presently being explored as a therapeutic approach for the treatment of neuropathic and cancer pain. In this study, we sought to use an injury-specific promoter to deliver the mu-opioid receptor (MOR) transgene such that expression would occur during the injured state only in response to release of injury-specific galanin. To determine whether an injury-specific promoter can produce neuron-specific MOR expression and enhanced antinociception, we compared animals infected with a galanin promoter virus (galMOR) or a human cytomegalovirus promoter virus (cmvMOR). In behavioral assays, we found an earlier onset and a larger magnitude of antinociception in animals infected with galMOR compared with cmvMOR. Immunohistochemical analysis of dorsal root ganglion neurons revealed a significant increase in MOR-positive staining in cmvMOR- and galMOR-treated mice. Spinal cord sections from galMOR-treated mice showed a greater increase in density but not area of MOR-positive staining. These results suggest that using injury-specific promoters to drive gene expression in primary afferent neurons can influence the onset and magnitude of antinociception in a rodent model of neuropathic pain and can be used to upregulate MOR expression in populations of neurons that are potentially injury specific. PERSPECTIVE An injury-specific promoter (galMOR) was used to drive MOR expression in a population- and injury-specific manner. GalMOR increased antinociception and density of MOR staining in the spinal cord. This article presents evidence that promoter selection is an important component in successful gene expression in an injury- and population-specific manner.
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Yang F, Zhang C, Xu Q, Tiwari V, He SQ, Wang Y, Dong X, Vera-Portocarrero LP, Wacnik PW, Raja SN, Guan Y. Electrical stimulation of dorsal root entry zone attenuates wide-dynamic-range neuronal activity in rats. Neuromodulation 2014; 18:33-40; discussion 40. [PMID: 25308522 DOI: 10.1111/ner.12249] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/09/2014] [Accepted: 07/22/2014] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Recent clinical studies suggest that neurostimulation at the dorsal root entry zone (DREZ) may alleviate neuropathic pain. However, the mechanisms of action for this therapeutic effect are unclear. Here, we examined whether DREZ stimulation inhibits spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. MATERIALS AND METHODS We conducted in vivo extracellular single-unit recordings of WDR neurons in rats after an L5 spinal nerve ligation (SNL) or sham surgery. We set bipolar electrical stimulation (50 Hz, 0.2 msec, 5 min) of the DREZ at the intensity that activated only Aα/β-fibers by measuring the lowest current at which DREZ stimulation evoked a peak antidromic sciatic Aα/β-compound action potential without inducing an Aδ/C-compound action potential (i.e., Ab1). RESULTS The elevated spontaneous activity rate of WDR neurons in SNL rats (n = 25; data combined from post-SNL groups at days 14-16 [n = 15] and days 45-75 [n = 10]) was significantly decreased from the prestimulation level (p < 0.01) at 0-15 min and 30-45 min post-stimulation. In both sham-operated (n = 8) and nerve-injured rats, DREZ stimulation attenuated the C-component, but not the A-component, of the WDR neuronal response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 msec) applied to the skin receptive field. Further, DREZ stimulation blocked windup (a form of brief neuronal sensitization) to repetitive noxious stimuli (0.5 Hz) at 0-15 min in all groups (p < 0.05). CONCLUSIONS Attenuation of WDR neuronal activity may contribute to DREZ stimulation-induced analgesia. This finding supports the notion that DREZ may be a useful target for neuromodulatory control of pain.
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Affiliation(s)
- Fei Yang
- Department of Anesthesiology and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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Caggiano V, Sur M, Bizzi E. Rostro-caudal inhibition of hindlimb movements in the spinal cord of mice. PLoS One 2014; 9:e100865. [PMID: 24963653 PMCID: PMC4071039 DOI: 10.1371/journal.pone.0100865] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/31/2014] [Indexed: 11/18/2022] Open
Abstract
Inhibitory neurons in the adult mammalian spinal cord are known to locally modulate afferent feedback - from muscle proprioceptors and from skin receptors - to pattern motor activity for locomotion and postural control. Here, using optogenetic tools, we explored how the same population of inhibitory interneurons globally affects hindlimb movements in the spinal cord of both anesthetized and freely moving mice. Activation of inhibitory interneurons up to the middle/lower spinal cord i.e. T8–T9, were able to completely and globally suppress all ipsilateral hindlimb movements. Furthermore, the same population of interneurons - which inhibited movements - did not significantly change the sensory and proprioceptive information from the affected limbs to the cortex. These results suggest a rostro-caudal organization of inhibition in the spinal cord motor output without modulation of ascending sensory pathways.
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Affiliation(s)
- Vittorio Caggiano
- McGovern Institute for Brain Research, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States of America
- * E-mail: (VC); (EB)
| | - Mirganka Sur
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States of America
| | - Emilio Bizzi
- McGovern Institute for Brain Research, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States of America
- * E-mail: (VC); (EB)
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Xu Q, Cheong YK, Yang F, Tiwari V, Li J, Liu J, Raja SN, Li W, Guan Y. Intrathecal carbenoxolone inhibits neuropathic pain and spinal wide-dynamic range neuronal activity in rats after an L5 spinal nerve injury. Neurosci Lett 2014; 563:45-50. [PMID: 24486838 DOI: 10.1016/j.neulet.2014.01.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 01/10/2014] [Accepted: 01/21/2014] [Indexed: 12/30/2022]
Abstract
Spinal glial gap junctions may play an important role in dorsal horn neuronal sensitization and neuropathic pain. In rats after an L5 spinal nerve ligation (SNL), we examined the effects of intrathecal injection of carbenoxolone (CBX), a gap junction decoupler, on neuropathic pain manifestations and on wide-dynamic range (WDR) neuronal activity in vivo. Intrathecal injection of CBX dose-dependently (0.1-50 μg, 10 μl) inhibited mechanical hypersensitivity in rats at 2-3 weeks post-SNL. However, the same doses of glycyrrhizic acid (an analogue of CBX that does not affect gap junctions) and mefloquine hydrochloride (a selective neuronal gap junction decoupler) were ineffective. Intrathecal CBX (5μg) also attenuated heat hypersensitivity in SNL rats. Further, rats did not develop tachyphylaxis to CBX-induced inhibition of mechanical hypersensitivity after repetitive drug treatments (25 μg/day) during days 14-16 post-SNL. Electrophysiological study in SNL rats showed that spinal topical application of CBX (100 μg, 50 μl), which mimics intrathecal drug administration, attenuated WDR neuronal responses to mechanical stimuli and to repetitive intracutaneous electrical stimuli (0.5 Hz) that induce windup, a short-form of activity-dependent neuronal sensitization. The current findings suggest that the inhibition of neuropathic pain manifestations by intrathecal injection of CBX in SNL rats may involve an inhibition of glial gap junctions and an attenuation of WDR neuronal activity in the dorsal horn.
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Affiliation(s)
- Qian Xu
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China; Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Yong-Kwan Cheong
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA; Department of Anesthesiology and Pain Medicine, School of Medicine, Wonkwang University, Iksan, Republic of Korea
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Jinheng Li
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Jian Liu
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Srinivasa N Raja
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Weiyan Li
- Department of Anesthesiology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu, China
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
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Yang F, Xu Q, Cheong YK, Shechter R, Sdrulla A, He SQ, Tiwari V, Dong X, Wacnik PW, Meyer R, Raja SN, Guan Y. Comparison of intensity-dependent inhibition of spinal wide-dynamic range neurons by dorsal column and peripheral nerve stimulation in a rat model of neuropathic pain. Eur J Pain 2014; 18:978-88. [PMID: 24390782 DOI: 10.1002/j.1532-2149.2013.00443.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND Spinal cord stimulation (SCS) and peripheral nerve stimulation (PNS) are thought to reduce pain by activating a sufficient number of large myelinated (Aβ) fibres, which in turn initiate spinal segmental mechanisms of analgesia. However, the volume of neuronal activity and how this activity is associated with different treatment targets is unclear under neuropathic pain conditions. METHODS We sought to delineate the intensity-dependent mechanisms of SCS and PNS analgesia by in vivo extracellular recordings from spinal wide-dynamic range neurons in nerve-injured rats. To mimic therapeutic SCS and PNS, we used bipolar needle electrodes and platinum hook electrodes to stimulate the dorsal column and the tibial nerve, respectively. Compound action potentials were recorded to calibrate the amplitude of conditioning stimulation required to activate A-fibres and thus titrate the volume of activation. RESULTS Dorsal column stimulation (50 Hz, five intensities) inhibited the windup (a short form of neuronal sensitization) and the C-component response of wide-dynamic range neurons to graded intracutaneous electrical stimuli in an intensity-dependent manner. Tibial nerve stimulation (50 Hz, three intensities) also suppressed the windup in an intensity-dependent fashion but did not affect the acute C-component response. CONCLUSIONS SCS and PNS may offer similar inhibition of short-term neuronal sensitization. However, only SCS attenuates spinal transmission of acute noxious inputs under neuropathic pain conditions. Our findings begin to differentiate peripheral from spinal-targeted neuromodulation therapies and may help to select the best stimulation target and optimum therapeutic intensity for pain treatment.
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Affiliation(s)
- F Yang
- Department of Anesthesiology and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, USA
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Bialosky JE, George SZ, Horn ME, Price DD, Staud R, Robinson ME. Spinal manipulative therapy-specific changes in pain sensitivity in individuals with low back pain (NCT01168999). THE JOURNAL OF PAIN 2013; 15:136-48. [PMID: 24361109 DOI: 10.1016/j.jpain.2013.10.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 10/08/2013] [Accepted: 10/17/2013] [Indexed: 12/30/2022]
Abstract
UNLABELLED Spinal manipulative therapy (SMT) is effective for some individuals experiencing low back pain; however, the mechanisms are not established regarding the role of placebo. SMT is associated with changes in pain sensitivity, suggesting related altered central nervous system response or processing of afferent nociceptive input. Placebo is also associated with changes in pain sensitivity, and the efficacy of SMT for changes in pain sensitivity beyond placebo has not been adequately considered. We randomly assigned 110 participants with low back pain to receive SMT, placebo SMT, placebo SMT with the instructional set "The manual therapy technique you will receive has been shown to significantly reduce low back pain in some people," or no intervention. Participants receiving the SMT and placebo SMT received their assigned intervention 6 times over 2 weeks. Pain sensitivity was assessed prior to and immediately following the assigned intervention during the first session. Clinical outcomes were assessed at baseline and following 2 weeks of participation in the study. Immediate attenuation of suprathreshold heat response was greatest following SMT (P = .05, partial η(2) = .07). Group-dependent differences were not observed for changes in pain intensity and disability at 2 weeks. Participant satisfaction was greatest following the enhanced placebo SMT. This study was registered at www.clinicaltrials.gov under the identifier NCT01168999. PERSPECTIVE The results of this study indicate attenuation of pain sensitivity is greater in response to SMT than the expectation of receiving an SMT. These findings suggest a potential mechanism of SMT related to lessening of central sensitization and may indicate a preclinical effect beyond the expectations of receiving SMT.
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Affiliation(s)
- Joel E Bialosky
- Department of Physical Therapy, Center for Pain Research and Behavioral Health, University of Florida, Gainesville, Florida.
| | - Steven Z George
- Department of Physical Therapy, Center for Pain Research and Behavioral Health, University of Florida, Gainesville, Florida
| | - Maggie E Horn
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Donald D Price
- Oral and Maxillofacial Surgery, Division of Neuroscience, University of Florida, Gainesville, Florida
| | - Roland Staud
- Department of Medicine, University of Florida, Gainesville, Florida
| | - Michael E Robinson
- Department of Clinical and Health Psychology, Center for Pain Research and Behavioral Health, University of Florida, Gainesville, Florida
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Shechter R, Yang F, Xu Q, Cheong YK, He SQ, Sdrulla A, Carteret AF, Wacnik PW, Dong X, Meyer RA, Raja SN, Guan Y. Conventional and kilohertz-frequency spinal cord stimulation produces intensity- and frequency-dependent inhibition of mechanical hypersensitivity in a rat model of neuropathic pain. Anesthesiology 2013; 119:422-32. [PMID: 23880991 DOI: 10.1097/aln.0b013e31829bd9e2] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Spinal cord stimulation (SCS) is a useful neuromodulatory technique for treatment of certain neuropathic pain conditions. However, the optimal stimulation parameters remain unclear. METHODS In rats after L5 spinal nerve ligation, the authors compared the inhibitory effects on mechanical hypersensitivity from bipolar SCS of different intensities (20, 40, and 80% motor threshold) and frequencies (50, 1 kHz, and 10 kHz). The authors then compared the effects of 1 and 50 Hz dorsal column stimulation at high- and low-stimulus intensities on conduction properties of afferent Aα/β-fibers and spinal wide-dynamic-range neuronal excitability. RESULTS Three consecutive daily SCS at different frequencies progressively inhibited mechanical hypersensitivity in an intensity-dependent manner. At 80% motor threshold, the ipsilateral paw withdrawal threshold (% preinjury) increased significantly from pre-SCS measures, beginning with the first day of SCS at the frequencies of 1 kHz (50.2 ± 5.7% from 23.9 ± 2.6%, n = 19, mean ± SEM) and 10 kHz (50.8 ± 4.4% from 27.9 ± 2.3%, n = 17), whereas it was significantly increased beginning on the second day in the 50 Hz group (38.9 ± 4.6% from 23.8 ± 2.1%, n = 17). At high intensity, both 1 and 50 Hz dorsal column stimulation reduced Aα/β-compound action potential size recorded at the sciatic nerve, but only 1 kHz stimulation was partially effective at the lower intensity. The number of actions potentials in C-fiber component of wide-dynamic-range neuronal response to windup-inducing stimulation was significantly decreased after 50 Hz (147.4 ± 23.6 from 228.1 ± 39.0, n = 13), but not 1 kHz (n = 15), dorsal column stimulation. CONCLUSIONS Kilohertz SCS attenuated mechanical hypersensitivity in a time course and amplitude that differed from conventional 50 Hz SCS, and may involve different peripheral and spinal segmental mechanisms.
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Affiliation(s)
- Ronen Shechter
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
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Xu Q, Li WY, Guan Y. Mu-opioidergic modulation differs in deep and superficial wide-dynamic range dorsal horn neurons in mice. Neurosci Lett 2013; 549:157-62. [PMID: 23748039 DOI: 10.1016/j.neulet.2013.05.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/16/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
Abstract
The spinal cord dorsal horn is an important action site for morphine analgesia. Wide-dynamic range (WDR) neurons in the dorsal horn are essential to spinal pain transmission and show increased excitability after repetitive noxious drive (windup). In light of differences in mu-opioid receptor distribution and neurophysiological properties of WDR neurons between deep and superficial dorsal horn, we recorded extracellular single-unit activity of WDR neurons from deep (350-700 μm) and superficial (<350 μm) dorsal horn in C57BL/6 mice and compared their responses to spinal superfusion of morphine (0.5mM, 30 μl) and naloxone (1mM, 30 μl). The windup level to repetitive electrical stimulation of 1.0 Hz (16 pulses, suprathreshold for C-fiber activation, 2.0 ms) was significantly decreased by morphine in deep (n=8), but not superficial (n=11), WDR neurons. However, the steady C-component response to graded intra-cutaneous electrical stimuli (0.01-5.0 mA, 2 ms) was significantly depressed by morphine only in superficial neurons. In separate experiments, spinal administration of naloxone facilitated the development of windup to 0.2 Hz stimulation in deep (n=10), but not superficial (n=8), WDR neurons. Accordingly, morphine and naloxone modulation of neuronal activity may be related to a specific effect on neuronal sensitization/plasticity in deep WDR neurons, whereas morphine inhibition may depress acute noxious inputs to superficial WDR neurons. Our study suggests that mu-opioidergic modulation may be different in deep and superficial WDR neurons.
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Affiliation(s)
- Qian Xu
- Department of Clinical Pharmacology, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu 210002, China
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Spinal cord stimulation: neurophysiological and neurochemical mechanisms of action. Curr Pain Headache Rep 2012; 16:217-25. [PMID: 22399391 DOI: 10.1007/s11916-012-0260-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chronic neuropathic pain can significantly reduce quality of life and place an economic burden on individuals and society. Spinal cord stimulation (SCS) is an alternative approach to the treatment of neuropathic pain when standard pharmacological agents have failed. However, an improved understanding of the mechanisms by which SCS inhibits pain is needed to enhance its clinical utility. This review summarizes important findings from recent studies of SCS in animal models of neuropathic pain, highlights current understanding of the spinal neurophysiological and neurochemical mechanisms by which SCS produces an analgesic effect, and discusses the potential clinical applicability of these findings and future directions for research.
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Schröder W, Vry J, Tzschentke TM, Jahnel U, Christoph T. Differential contribution of opioid and noradrenergic mechanisms of tapentadol in rat models of nociceptive and neuropathic pain. Eur J Pain 2012; 14:814-21. [DOI: 10.1016/j.ejpain.2010.05.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 04/28/2010] [Accepted: 05/10/2010] [Indexed: 11/15/2022]
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A peripheral adrenoceptor-mediated sympathetic mechanism can transform stress-induced analgesia into hyperalgesia. Anesthesiology 2011; 114:1403-16. [PMID: 21540738 DOI: 10.1097/aln.0b013e31821c3878] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Stress has paradoxical effects on pain, causing stress-induced analgesia but also exacerbating pain via poorly understood mechanisms. Adrenergic neurotransmission is integral in pathways that regulate the response to both pain and stress. Hyperalgesia is often associated with enhanced adrenergic sensitivity of primary afferents, but sympathetic nervous system outflow has not been demonstrated to exacerbate pain perception after stress. METHODS Rats or C57/BL6 wild-type mice treated with α-2 receptor antagonists or α-2A receptor knockout mice were exposed to ultrasonic noise stress or footshock stress and subsequently tested for hotplate paw withdrawal latencies. The sensory sensitivity of α-2A knockout mice to electrical and chemical stimuli was tested neurophysiologically and behaviorally. The effects of sympatholytic treatments were investigated. RESULTS Noise and footshock stressors induced thermal hyperalgesia in rats pretreated systemically with α-2 antagonists. Wild-type mice pretreated with α-2 antagonists and α-2A knockout mice also exhibited thermal hyperalgesia induced by noise stress. Local spinal or intraplantar injection of an α-2 antagonist counteracted stress-induced analgesia without causing hyperalgesia. The α-2A knockout mice had decreased thresholds for peripheral sensitization with sulprostone and for windup of the dorsal horn neuronal response to repetitive electrical stimuli. Stress-induced hyperalgesia was abolished and the sensitization was attenuated by sympathectomy or systemic administration of an α-1-adrenergic antagonist. CONCLUSIONS Sympathetic postganglionic nerves can enhance pain sensation via a peripheral α-1-adrenoceptor mechanism when sympathetic outflow is disinhibited. The net effect of stress on pain sensation reflects a balance between descending spinal inhibition and sympathetic outflow that can shift toward pain facilitation when central and peripheral α-2-adrenoceptor inhibitory mechanisms are attenuated.
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Guan Y, Raja SN. Wide-dynamic-range neurons are heterogeneous in windup responsiveness to changes in stimulus intensity and isoflurane anesthesia level in mice. J Neurosci Res 2010; 88:2272-83. [PMID: 20209628 DOI: 10.1002/jnr.22383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The windup phenomenon in wide-dynamic-range (WDR) neurons represents a short-term neuronal sensitization to repetitive noxious inputs that may share similar mechanisms with those that trigger the development of persistent pain and hyperalgesia. Some WDR cells are readily sensitized and express prominent windup (windup(+)), whereas others do not (windup(-)). We recorded extracellular single-unit activity of deep laminae WDR neurons (350-700 microm) in C57BL/6 mice to determine how changes in stimulus intensity (1x and >2x C-component threshold, n = 53) and concentrations of isoflurane anesthesia (2.0% and 1.0%, n = 30) might differently modulate windup responsiveness in windup(+) and windup(-) cells. Two principally different analysis methods [absolute windup (the number of action potentials) and relative windup (the percentage of action potentials evoked by the first stimulus of the train)] were used to interpret windup data. We observed that increasing the stimulus intensity and decreasing the isoflurane concentration: 1) facilitated windup generation at 0.2-Hz stimulation and significantly enhanced absolute windup at both 0.2-Hz and 0.5-Hz stimulation predominantly in windup(+) cells but did not confer windup capability on windup(-) cells and 2) significantly increased relative windup at 0.2-Hz, but not 0.5-Hz, stimulation in windup(+) cells. Our findings advance our understanding of the neurobiology of deep WDR neurons in mice and demonstrate that two populations of cells differ in their windup responsiveness to changes in experimental conditions. We also elucidate the usefulness and potential limitations of two widely used methods for calculating and presenting windup data.
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Affiliation(s)
- Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Mas-related G-protein-coupled receptors inhibit pathological pain in mice. Proc Natl Acad Sci U S A 2010; 107:15933-8. [PMID: 20724664 DOI: 10.1073/pnas.1011221107] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
An important objective of pain research is to identify novel drug targets for the treatment of pathological persistent pain states, such as inflammatory and neuropathic pain. Mas-related G-protein-coupled receptors (Mrgprs) represent a large family of orphan receptors specifically expressed in small-diameter nociceptive primary sensory neurons. To determine the roles of Mrgprs in persistent pathological pain states, we exploited a mouse line in which a chromosomal locus spanning 12 Mrgpr genes was deleted (KO). Initial studies indicated that these KO mice show prolonged mechanical- and thermal-pain hypersensitivity after hind-paw inflammation compared with wild-type littermates. Here, we show that this mutation also enhances the windup response of dorsal-horn wide dynamic-range neurons, an electrophysiological model for the triggering of central pain sensitization. Deletion of the Mrgpr cluster also blocked the analgesic effect of intrathecally applied bovine adrenal medulla peptide 8-22 (BAM 8-22), an MrgprC11 agonist, on both inflammatory heat hyperalgesia and neuropathic mechanical allodynia. Spinal application of bovine adrenal medulla peptide 8-22 also significantly attenuated windup in wild-type mice, an effect eliminated in KO mice. These data suggest that members of the Mrgpr family, in particular MrgprC11, may constitute an endogenous inhibitory mechanism for regulating persistent pain in mice. Agonists for these receptors may, therefore, represent a class of antihyperalgesics for treating persistent pain with minimal side effects because of the highly specific expression of their targets.
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Aguiar P, Sousa M, Lima D. NMDA Channels Together With L-Type Calcium Currents and Calcium-Activated Nonspecific Cationic Currents Are Sufficient to Generate Windup in WDR Neurons. J Neurophysiol 2010; 104:1155-66. [DOI: 10.1152/jn.00834.2009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Windup is characterized as a frequency-dependent increase in the number of evoked action potentials in dorsal horn neurons in response to electrical stimulation of afferent C-fibers. This phenomenon was first described in the mid-60s, but the core mechanisms behind it still remain elusive. Several factors affecting its dynamics have been identified, but the distinction between modulating mechanisms from generating mechanisms is not always clear. Several mechanisms contribute to the excitation of dorsal horn neurons exhibiting windup, and one of our main aims was to help making this distinction. The approach presented here relies on mathematical and computational analysis to study the mechanism(s) underlying windup. From experimentally obtained windup profiles, we extract the time scale of the facilitation mechanisms that may support the characteristics of windup. Guided by these values and using simulations of a biologically realistic compartmental model of a wide dynamic range (WDR) neuron, we are able to assess the contribution of each mechanism for the generation of action potentials windup. We show that the key mechanisms giving rise to windup is the temporal summation of N-methyl-d-aspartate (NMDA) long-lasting postsynaptic responses taking place on top of a membrane potential cumulative depolarization. Calcium-activated nonspecific cationic currents driven by calcium influx from L-type calcium channels and synaptic currents support this cumulative depolarization and plateau formation in WDR neuron membrane potential. The effects of different nonhomogeneous stimulation protocols are explored, and their important role in clarifying many aspects of the windup generation is shown. The models are used to produce several predictions that can be tested experimentally.
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Affiliation(s)
- P. Aguiar
- Centro de Matemática da Universidade do Porto
- Instituto de Biologia Molecular e Celular, Universidade do Porto; and
| | - M. Sousa
- Instituto de Biologia Molecular e Celular, Universidade do Porto; and
| | - D. Lima
- Instituto de Biologia Molecular e Celular, Universidade do Porto; and
- Laboratório de Biologia Celular e Molecular, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
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