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Villalón Landeros E, Kho SC, Church TR, Brennan A, Türker F, Delannoy M, Caterina MJ, Margolis SS. The nociceptive activity of peripheral sensory neurons is modulated by the neuronal membrane proteasome. Cell Rep 2024; 43:114058. [PMID: 38614084 DOI: 10.1016/j.celrep.2024.114058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/05/2024] [Accepted: 03/20/2024] [Indexed: 04/15/2024] Open
Abstract
Proteasomes are critical for peripheral nervous system (PNS) function. Here, we investigate mammalian PNS proteasomes and reveal the presence of the neuronal membrane proteasome (NMP). We show that specific inhibition of the NMP on distal nerve fibers innervating the mouse hind paw leads to reduction in mechanical and pain sensitivity. Through investigating PNS NMPs, we demonstrate their presence on the somata and proximal and distal axons of a subset of dorsal root ganglion (DRG) neurons. Single-cell RNA sequencing experiments reveal that the NMP-expressing DRGs are primarily MrgprA3+ and Cysltr2+. NMP inhibition in DRG cultures leads to cell-autonomous and non-cell-autonomous changes in Ca2+ signaling induced by KCl depolarization, αβ-meATP, or the pruritogen histamine. Taken together, these data support a model whereby NMPs are expressed on a subset of somatosensory DRGs to modulate signaling between neurons of distinct sensory modalities and indicate the NMP as a potential target for controlling pain.
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Affiliation(s)
- Eric Villalón Landeros
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Samuel C Kho
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taylor R Church
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anna Brennan
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fulya Türker
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael Delannoy
- Microscopy Facility, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael J Caterina
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurosurgery and Neurosurgery Pain Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seth S Margolis
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Hall BE, Mazhar K, Macdonald E, Cassidy M, Doty M, Judkins C, Terse A, Shiers S, Tadros S, Yun S, Burton MD, Price TJ, Kulkarni A. Transcriptome Analysis of Rheumatoid Arthritis Uncovers Genes Linked to Inflammation-Induced Pain. Res Sq 2024:rs.3.rs-4218885. [PMID: 38712195 PMCID: PMC11071542 DOI: 10.21203/rs.3.rs-4218885/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Autoimmune diseases such as rheumatoid arthritis (RA) can promote states of chronic inflammation with accompanying tissue destruction and pain. RA can cause inflammatory synovitis in peripheral joints, particularly within the hands and feet, but can also sometimes trigger temporomandibular joint (TMJ) arthralgia. To better understand the effects of ongoing inflammation-induced pain signaling, dorsal root ganglia (DRGs) were acquired from individuals with RA for transcriptomic study. We conducted RNA sequencing from the L5 DRGs because it contains the soma of the sensory neurons that innervate the affected joints in the foot. DRGs from 5 RA patients were compared with 9 non-arthritic controls. RNA-seq of L5 DRGs identified 128 differentially expressed genes (DEGs) that were dysregulated in the RA subjects as compared to the non-arthritic controls. The DRG resides outside the blood brain barrier and, as such, our initial transcriptome analysis detected signs of an autoimmune disorder including the upregulated expression of immunoglobulins and other immunologically related genes within the DRGs of the RA donors. Additionally, we saw the upregulation in genes implicated in neurogenesis that could promote pain hypersensitivity. Overall, our DRG analysis suggests that there are upregulated inflammatory and pain signaling pathways that can contribute to chronic pain in RA.
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Singleton H, Mahato P, Arden-Close E, Thomas S, Ersser S, Holley D, Yang X, Roberts A. Virtual reality used to distract children and young people with long-term conditions from pain or pruritus: A scoping review using PAGER. J Clin Nurs 2024; 33:469-480. [PMID: 37962251 DOI: 10.1111/jocn.16928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 09/13/2023] [Accepted: 10/18/2023] [Indexed: 11/15/2023]
Abstract
AIMS AND OBJECTIVES To map out the primary research studies relating to how virtual reality (VR) has been used to distract children and young people with long-term conditions from pain or pruritus. BACKGROUND Pharmacologic treatment of chronic pain and pruritus may have side effects; hence, non-invasive non-pharmacological treatments are being sought. DESIGN The scoping review followed the methodology recommended by the Joanna Briggs Institute, PAGER framework and PRISMA-ScR checklist. The protocol was registered with the Open Science Registration on 14 February 2022 https//doi.org/10.17605/OSF.IO/K2R93. METHODS Five databases (Medline, CINAHL, PsycINFO, Web of Science and Scopus) were searched. Data were extracted from primary research studies published between 2000 and 2022 involving children and adolescent populations (<21 years) with a long-term condition that had an element of enduring pruritus and/or pain. RESULTS Of 464 abstracts screened, 35 full-text papers were assessed with 5 studies meeting the eligibility criteria. Three main themes emerged from the included studies: (1) Improvements in pain and daily functioning; (2) positive perceptions of VR and (3) accessibility and feasibility of VR. No papers were found on the effect of VR on alleviating pruritus. CONCLUSION VR is feasible, acceptable, and safe for children and adolescents with chronic pain in a range of long-term conditions and offers promise as an adjunctive treatment for improving chronic pain and quality of life. No studies were identified that targeted pruritis or measured pruritis outcomes; thus, the effects of VR for pruritis are unknown. There is a need for rigorously designed, randomised controlled trials to test the clinical and cost-effectiveness of VR interventions for chronic pain and pruritis in children and adolescents. The use of the PAGER (Patterns, Advances, Gaps, Evidence for Practice and Research Recommendations) framework for scoping reviews helped to structure analysis and findings and identify research gaps. RELEVANCE TO CLINICAL PRACTICE VR interventions offer promise in improving chronic pain related to long-term conditions.
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Affiliation(s)
| | | | | | | | | | | | | | - Amanda Roberts
- Nottingham Support for Carers of Children with Eczema, Nottingham, UK
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Dedek C, Azadgoleh MA, Prescott SA. Reproducible and fully automated testing of nocifensive behavior in mice. Cell Rep Methods 2023; 3:100650. [PMID: 37992707 PMCID: PMC10783627 DOI: 10.1016/j.crmeth.2023.100650] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 09/11/2023] [Accepted: 10/30/2023] [Indexed: 11/24/2023]
Abstract
Pain in rodents is often inferred from their withdrawal from noxious stimulation. Threshold stimulus intensity or response latency is used to quantify pain sensitivity. This usually involves applying stimuli by hand and measuring responses by eye, which limits reproducibility and throughput. We describe a device that standardizes and automates pain testing by providing computer-controlled aiming, stimulation, and response measurement. Optogenetic and thermal stimuli are applied using blue and infrared light, respectively. Precise mechanical stimulation is also demonstrated. Reflectance of red light is used to measure paw withdrawal with millisecond precision. We show that consistent stimulus delivery is crucial for resolving stimulus-dependent variations in withdrawal and for testing with sustained stimuli. Moreover, substage video reveals "spontaneous" behaviors for consideration alongside withdrawal metrics to better assess the pain experience. The entire process was automated using machine learning. RAMalgo (reproducible automated multimodal algometry) improves the standardization, comprehensiveness, and throughput of preclinical pain testing.
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Affiliation(s)
- Christopher Dedek
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada
| | - Mehdi A Azadgoleh
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Steven A Prescott
- Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G9, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
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Fiebig A, Leibl V, Oostendorf D, Lukaschek S, Frömbgen J, Masoudi M, Kremer AE, Strupf M, Reeh P, Düll M, Namer B. Peripheral signaling pathways contributing to non-histaminergic itch in humans. J Transl Med 2023; 21:908. [PMID: 38087354 PMCID: PMC10717026 DOI: 10.1186/s12967-023-04698-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 11/04/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND Chronic itch (chronic pruritus) is a major therapeutic challenge that remains poorly understood despite the extensive recent analysis of human pruriceptors. It is unclear how the peripheral nervous system differentiates the signaling of non-histaminergic itch and pain. METHODS Here we used psychophysical analysis and microneurography (single nerve fiber recordings) in healthy human volunteers to explore the distinct signaling mechanisms of itch, using the pruritogens β-alanine, BAM 8-22 and cowhage extract. RESULTS The mode of application (injection or focal application using inactivated cowhage spicules) influenced the itch/pain ratio in sensations induced by BAM 8-22 and cowhage but not β-alanine. We found that sensitizing pre-injections of prostaglandin E2 increased the pain component of BAM 8-22 but not the other pruritogens. A-fibers contributed only to itch induced by β-alanine. TRPV1 and TRPA1 were necessary for itch signaling induced by all three pruritogens. In single-fiber recordings, we found that BAM 8-22 and β-alanine injection activated nearly all CM-fibers (to different extents) but not CMi-fibers, whereas cowhage extract injection activated only 56% of CM-fibers but also 25% of CMi-fibers. A "slow bursting discharge pattern" was evoked in 25% of CM-fibers by β-alanine, in 35% by BAM 8-22, but in only 10% by cowhage extract. CONCLUSION Our results indicate that no labeled line exists for these pruritogens in humans. A combination of different mechanisms, specific for each pruritogen, leads to itching sensations rather than pain. Notably, non-receptor-based mechanisms such as spatial contrast or discharge pattern coding seem to be important processes. These findings will facilitate the discovery of therapeutic targets for chronic pruritus, which are unlikely to be treated effectively by single receptor blockade.
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Affiliation(s)
- Andrea Fiebig
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Institute of Neurophysiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Victoria Leibl
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - David Oostendorf
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Saskia Lukaschek
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Institute of Neurophysiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Jens Frömbgen
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research, Faculty of Medicine, RWTH Aachen University, Aachen, Germany
- Institute of Neurophysiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Maral Masoudi
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Andreas E Kremer
- Department of Gastroenterology and Hepatology, University Hospital Zürich, University of Zürich, Zurich, Switzerland
| | - Marion Strupf
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Peter Reeh
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
| | - Miriam Düll
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany
- Department of Medicine 1, University Hospital Erlangen and Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Namer
- Research Group Neuroscience, Interdisciplinary Centre for Clinical Research, Faculty of Medicine, RWTH Aachen University, Aachen, Germany.
- Institute of Neurophysiology, Uniklinik RWTH Aachen University, Aachen, Germany.
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany.
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Uniyal A, Tiwari V, Tsukamoto T, Dong X, Guan Y, Raja SN. Targeting sensory neuron GPCRs for peripheral neuropathic pain. Trends Pharmacol Sci 2023; 44:1009-1027. [PMID: 37977131 PMCID: PMC10657387 DOI: 10.1016/j.tips.2023.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/29/2023] [Accepted: 10/10/2023] [Indexed: 11/19/2023]
Abstract
Despite the high prevalence of peripheral neuropathic pain (NP) conditions and significant progress in understanding its underlying mechanisms, the management of peripheral NP remains inadequate. Existing pharmacotherapies for NP act primarily on the central nervous system (CNS) and are often associated with CNS-related adverse effects, limiting their clinical effectiveness. Mounting preclinical evidence indicates that reducing the heightened activity in primary sensory neurons by targeting G-protein-coupled receptors (GPCRs), without activating these receptors in the CNS, relieves pain without central adverse effects. In this review, we focus on recent advancements in GPCR-mediated peripheral pain relief and discuss strategies to advance the development of more effective and safer therapies for peripheral NP by shifting from traditional CNS modulatory approaches toward selective targeting of GPCRs on primary sensory neurons.
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Affiliation(s)
- Ankit Uniyal
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD, USA
| | - Vinod Tiwari
- Neuroscience and Pain Research Laboratory, Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology (B.H.U), Varanasi, India
| | - Takashi Tsukamoto
- Department of Neurology and Johns Hopkins Drug Discovery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinzhong Dong
- Department of Neuroscience, The Johns Hopkins University, Baltimore, MD, USA
| | - Yun Guan
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD, USA; Department of Neurological Surgery, The Johns Hopkins University, Baltimore, MD, USA
| | - Srinivasa N Raja
- Division of Pain Medicine, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD, USA; Department of Neurology and Johns Hopkins Drug Discovery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Guo C, Jiang H, Huang CC, Li F, Olson W, Yang W, Fleming M, Yu G, Hoekel G, Luo W, Liu Q. Pain and itch coding mechanisms of polymodal sensory neurons. Cell Rep 2023; 42:113316. [PMID: 37889748 PMCID: PMC10729537 DOI: 10.1016/j.celrep.2023.113316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 09/05/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
Pain and itch coding mechanisms in polymodal sensory neurons remain elusive. MrgprD+ neurons represent a major polymodal population and mediate both mechanical pain and nonhistaminergic itch. Here, we show that chemogenetic activation of MrgprD+ neurons elicited both pain- and itch-related behavior in a dose-dependent manner, revealing an unanticipated compatibility between pain and itch in polymodal neurons. While VGlut2-dependent glutamate release is required for both pain and itch transmission from MrgprD+ neurons, the neuropeptide neuromedin B (NMB) is selectively required for itch signaling. Electrophysiological recordings further demonstrated that glutamate synergizes with NMB to excite NMB-sensitive postsynaptic neurons. Ablation of these spinal neurons selectively abolished itch signals from MrgprD+ neurons, without affecting pain signals, suggesting a dedicated itch-processing central circuit. These findings reveal distinct neurotransmitters and neural circuit requirements for pain and itch signaling from MrgprD+ polymodal sensory neurons, providing new insights on coding and processing of pain and itch.
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Affiliation(s)
- Changxiong Guo
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Haowu Jiang
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Cheng-Chiu Huang
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Fengxian Li
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - William Olson
- Department of Neuroscience, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Weishan Yang
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Michael Fleming
- Department of Neuroscience, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Guang Yu
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - George Hoekel
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Wenqin Luo
- Department of Neuroscience, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Qin Liu
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.
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Li DJ, Zhong ZJ, Wang XL, Wei N, Zhao SJ, Shan TT, Liu YP, Yu YQ. Chemokine receptor CXCR2 in primary sensory neurons of trigeminal ganglion mediates orofacial itch. Front Mol Neurosci 2023; 16:1279237. [PMID: 37953876 PMCID: PMC10637378 DOI: 10.3389/fnmol.2023.1279237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/16/2023] [Indexed: 11/14/2023] Open
Abstract
The CXCR2 chemokine receptor is known to have a significant impact on the initiation and control of inflammatory processes. However, its specific involvement in the sensation of itch is not yet fully understood. In this study, we aimed to elucidate the function of CXCR2 in the trigeminal ganglion (TG) by utilizing orofacial itch models induced by incision, chloroquine (CQ), and histamine. Our results revealed a significant up-regulation of CXCR2 mRNA and protein expressions in the primary sensory neurons of TG in response to itch stimuli. The CXCR2 inhibitor SB225002 resulted in notable decrease in CXCR2 protein expression and reduction in scratch behaviors. Distal infraorbital nerve (DION) microinjection of a specific shRNA virus inhibited CXCR2 expression in TG neurons and reversed itch behaviors. Additionally, the administration of the PI3K inhibitor LY294002 resulted in a decrease in the expressions of p-Akt, Akt, and CXCR2 in TG neurons, thereby mitigating pruritic behaviors. Collectively, we report that CXCR2 in the primary sensory neurons of trigeminal ganglion contributes to orofacial itch through the PI3K/Akt signaling pathway. These observations highlight the potential of molecules involved in the regulation of CXCR2 as viable therapeutic targets for the treatment of itch.
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Affiliation(s)
- Dong-Jin Li
- College of Life Sciences, Northwest University, Xi’an, China
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Zhen-Juan Zhong
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Xiao-Liang Wang
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Na Wei
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Si-Jia Zhao
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Ting-Ting Shan
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Ya-Ping Liu
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Yao-Qing Yu
- College of Life Sciences, Northwest University, Xi’an, China
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
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Qin Z, Xiang L, Zheng S, Zhao Y, Qin Y, Zhang L, Zhou L. Vitexin inhibits pain and itch behavior via modulating TRPV4 activity in mice. Biomed Pharmacother 2023; 165:115101. [PMID: 37406508 DOI: 10.1016/j.biopha.2023.115101] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 07/07/2023] Open
Abstract
Itching and pain are distinct unpleasant sensations. The transient receptor potential cation channel subfamily V member 4 (TRPV4) pathway is regarded as a shared pathway that mediates pain and itching. Vitexin (Mujingsu, MJS), a C-glycosylflavonoid, is an effective analgesic. This study aimed to explore the antinociceptive and anti-pruritic effects of MJS and whether its effects are mediated via the TRPV4 pathway. Mice were treated with MJS (7.5 mg/kg) 0.5 h prior to the initiation of the pain or itch modeling process. The results showed that MJS suppressed pain-like behavior in hot plate, thermal infiltration, glacial acetic acid twisting, and formalin tests. Administration of MJS decreased the pruritus response induced by histamine, C48/80, chloroquine and BAM8-22 within 30 min. MJS reduced scratching bouts and lessened the wiping reaction of mice under TRPV4 activation by GSK101 (10 µg/5 μl). MJS inhibited scratching behavior in acetone-ether-water (AEW)-treated mice within 60 min. An H1 receptor antagonist-chlorpheniramine (CLP, 400 mg/kg)-and a TRPV4 antagonist-HC067047 (250 ng/kg), exhibited similar effects to those of MJS. Moreover, MJS ameliorated dry skin itch-associated cutaneous barrier disruption in mice. MJS did not inhibit the expression of TRPV4 in the dorsal root ganglion neurons at L2-L3 in AEW mice. These results indicate that the analgesic and anti-pruritic effects of MJS in acute and chronic pain and itching, as well as itching caused by TRPV4 activation, could be attributed to the TRPV4 pathway modulation.
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Affiliation(s)
- Zhiqiang Qin
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Lan Xiang
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Siyu Zheng
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Yuchen Zhao
- Department of Mathematics, University of California, Los Angeles, CA 90095, USA
| | - Yanyan Qin
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Lei Zhang
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Lanlan Zhou
- School of Medical Technology and Nursing, Shenzhen Polytechnic, Shenzhen 518055, China.
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10
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Affiliation(s)
- Jussi Kupari
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrik Ernfors
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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11
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Wang L, Su X, Yan J, Wu Q, Xu X, Wang X, Liu X, Song X, Zhang Z, Hu W, Liu X, Zhang Y. Involvement of Mrgprd-expressing nociceptors-recruited spinal mechanisms in nerve injury-induced mechanical allodynia. iScience 2023; 26:106764. [PMID: 37250305 PMCID: PMC10214713 DOI: 10.1016/j.isci.2023.106764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 03/17/2023] [Accepted: 04/24/2023] [Indexed: 05/31/2023] Open
Abstract
Mechanical allodynia and hyperalgesia are intractable symptoms lacking effective clinical treatments in patients with neuropathic pain. However, whether and how mechanically responsive non-peptidergic nociceptors are involved remains elusive. Here, we showed that von Frey-evoked static allodynia and aversion, along with mechanical hyperalgesia after spared nerve injury (SNI) were reduced by ablation of MrgprdCreERT2-marked neurons. Electrophysiological recordings revealed that SNI-opened Aβ-fiber inputs to laminae I-IIo and vIIi, as well as C-fiber inputs to vIIi, were all attenuated in Mrgprd-ablated mice. In addition, priming chemogenetic or optogenetic activation of Mrgprd+ neurons drove mechanical allodynia and aversion to low-threshold mechanical stimuli, along with mechanical hyperalgesia. Mechanistically, gated Aβ and C inputs to vIIi were opened, potentially via central sensitization by dampening potassium currents. Altogether, we uncovered the involvement of Mrgprd+ nociceptors in nerve injury-induced mechanical pain and dissected the underlying spinal mechanisms, thus providing insights into potential therapeutic targets for pain management.
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Affiliation(s)
- Liangbiao Wang
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Xiaojing Su
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Jinjin Yan
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Qiaofeng Wu
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Xiang Xu
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Xinyue Wang
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Xiaoqing Liu
- School of Basic Medical Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaoyuan Song
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zhi Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Hu
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Xinfeng Liu
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
| | - Yan Zhang
- Department of Neurology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, China
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12
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Pan Q, Guo SS, Chen M, Su XY, Gao ZL, Wang Q, Xu TL, Liu MG, Hu J. Representation and control of pain and itch by distinct prefrontal neural ensembles. Neuron 2023:S0896-6273(23)00342-2. [PMID: 37224813 DOI: 10.1016/j.neuron.2023.04.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 02/18/2023] [Accepted: 04/27/2023] [Indexed: 05/26/2023]
Abstract
Pain and itch are two closely related but essentially distinct sensations that elicit different behavioral responses. However, it remains mysterious how pain and itch information is encoded in the brain to produce differential perceptions. Here, we report that nociceptive and pruriceptive signals are separately represented and processed by distinct neural ensembles in the prelimbic (PL) subdivision of the medial prefrontal cortex (mPFC) in mice. Pain- and itch-responsive cortical neural ensembles were found to significantly differ in electrophysiological properties, input-output connectivity profiles, and activity patterns to nociceptive or pruriceptive stimuli. Moreover, these two groups of cortical neural ensembles oppositely modulate pain- or itch-related sensory and emotional behaviors through their preferential projections to specific downstream regions such as the mediodorsal thalamus (MD) and basolateral amygdala (BLA). These findings uncover separate representations of pain and itch by distinct prefrontal neural ensembles and provide a new framework for understanding somatosensory information processing in the brain.
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Affiliation(s)
- Qian Pan
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Su-Shan Guo
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ming Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xin-Yu Su
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zi-Long Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qi Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tian-Le Xu
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Songjiang Hospital and Songjiang Research Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 201600, China; Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai 201210, China.
| | - Ming-Gang Liu
- Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai 200030, China.
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13
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Liu AW, Gillis JE, Sumpter TL, Kaplan DH. Neuroimmune interactions in atopic and allergic contact dermatitis. J Allergy Clin Immunol 2023; 151:1169-1177. [PMID: 37149370 PMCID: PMC10167546 DOI: 10.1016/j.jaci.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 05/08/2023]
Abstract
The skin is a barrier organ populated by many types of skin-resident immune cells and sensory neurons. It has become increasingly appreciated that neuroimmune interactions are an important component of inflammatory diseases such as atopic dermatitis and allergic contact dermatitis. Neuropeptides secreted from nerve terminals play an important role in mediating cutaneous immune cell function, and soluble mediators derived from immune cells interact with neurons to induce itch. In this review article, we will explore emerging research describing neuronal effector functions on skin immune cells in mouse models of atopic and contact dermatitis. We will also discuss the contributions of both specific neuronal subsets and secreted immune factors to itch induction and the associated inflammatory processes. Finally, we will explore how treatment strategies have emerged around these findings and discuss the relationship between scratching and dermatitis.
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Affiliation(s)
- Andrew W Liu
- Department of Dermatology, University of Pittsburgh, Pittsburgh, Pa; Department of Immunology, University of Pittsburgh, Pittsburgh, Pa
| | - Jacob E Gillis
- Department of Dermatology, University of Pittsburgh, Pittsburgh, Pa; Department of Immunology, University of Pittsburgh, Pittsburgh, Pa
| | - Tina L Sumpter
- Department of Dermatology, University of Pittsburgh, Pittsburgh, Pa; Department of Immunology, University of Pittsburgh, Pittsburgh, Pa
| | - Daniel H Kaplan
- Department of Dermatology, University of Pittsburgh, Pittsburgh, Pa; Department of Immunology, University of Pittsburgh, Pittsburgh, Pa.
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14
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Lu P, Zhao Y, Xie Z, Zhou H, Dong X, Wu GF, Kim BS, Feng J, Hu H. MrgprA3-expressing pruriceptors drive pruritogen-induced alloknesis through mechanosensitive Piezo2 channel. Cell Rep 2023; 42:112283. [PMID: 36961815 PMCID: PMC10514240 DOI: 10.1016/j.celrep.2023.112283] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 01/29/2023] [Accepted: 03/03/2023] [Indexed: 03/25/2023] Open
Abstract
Although touch and itch are coded by distinct neuronal populations, light touch also provokes itch in the presence of exogenous pruritogens, resulting in a phenomenon called alloknesis. However, the cellular and molecular mechanisms underlying the initiation of pruritogen-induced mechanical itch sensitization are poorly understood. Here, we show that intradermal injections of histamine or chloroquine (CQ) provoke alloknesis through activation of TRPV1- and MrgprA3-expressing prurioceptors, and functional ablation of these neurons reverses pruritogen-induced alloknesis. Moreover, genetic ablation of mechanosensitive Piezo2 channel function from MrgprA3-expressing prurioceptors also dampens pruritogen-induced alloknesis. Mechanistically, histamine and CQ sensitize Piezo2 channel function, at least in part, through activation of the phospholipase C (PLC) and protein kinase C-δ (PKCδ) signaling. Collectively, our data find a TRPV1+/MrgprA3+ prurioceptor-Piezo2 signaling axis in the initiation of pruritogen-induced mechanical itch sensitization in the skin.
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Affiliation(s)
- Ping Lu
- Department of Anesthesiology, The Center for the Study of Itch & Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA; Dermatology Hospital, Southern Medical University, Guangzhou, China
| | - Yonghui Zhao
- Department of Anesthesiology, The Center for the Study of Itch & Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Zili Xie
- Department of Anesthesiology, The Center for the Study of Itch & Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Huan Zhou
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Gregory F Wu
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Brian S Kim
- Kimberly and Eric J. Waldman Department of Dermatology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jing Feng
- Department of Anesthesiology, The Center for the Study of Itch & Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA; Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Science, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Hongzhen Hu
- Department of Anesthesiology, The Center for the Study of Itch & Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA.
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15
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Liu Y, Cao C, Huang XP, Gumpper RH, Rachman MM, Shih SL, Krumm BE, Zhang S, Shoichet BK, Fay JF, Roth BL. Ligand recognition and allosteric modulation of the human MRGPRX1 receptor. Nat Chem Biol 2023; 19:416-422. [PMID: 36302898 DOI: 10.1038/s41589-022-01173-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/13/2022] [Indexed: 11/09/2022]
Abstract
The human MAS-related G protein-coupled receptor X1 (MRGPRX1) is preferentially expressed in the small-diameter primary sensory neurons and involved in the mediation of nociception and pruritus. Central activation of MRGPRX1 by the endogenous opioid peptide fragment BAM8-22 and its positive allosteric modulator ML382 has been shown to effectively inhibit persistent pain, making MRGPRX1 a promising target for non-opioid pain treatment. However, the activation mechanism of MRGPRX1 is still largely unknown. Here we report three high-resolution cryogenic electron microscopy structures of MRGPRX1-Gαq in complex with BAM8-22 alone, with BAM8-22 and ML382 simultaneously as well as with a synthetic agonist compound-16. These structures reveal the agonist binding mode for MRGPRX1 and illuminate the structural requirements for positive allosteric modulation. Collectively, our findings provide a molecular understanding of the activation and allosteric modulation of the MRGPRX1 receptor, which could facilitate the structure-based design of non-opioid pain-relieving drugs.
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Affiliation(s)
- Yongfeng Liu
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Can Cao
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Ryan H Gumpper
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Moira M Rachman
- Department of Pharmaceutical Sciences, University of California, San Francisco School of Medicine, San Francisco, CA, USA
| | - Sheng-Luen Shih
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Brian E Krumm
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Shicheng Zhang
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Brian K Shoichet
- Department of Pharmaceutical Sciences, University of California, San Francisco School of Medicine, San Francisco, CA, USA
| | - Jonathan F Fay
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
- National Institute of Mental Health Psychoactive Drug Screening Program, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
- Division of Chemical Biology and Medicinal Chemistry, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
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16
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Black CJ, Saab CY, Borton DA. Transient gamma events delineate somatosensory modality in S1. bioRxiv 2023:2023.03.30.534945. [PMID: 37034800 PMCID: PMC10081264 DOI: 10.1101/2023.03.30.534945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Gamma band activity localized to the primary somatosensory cortex (S1) in humans and animals is implicated in the higher order neural processing of painful and tactile stimuli. However, it is unclear if gamma band activity differs between these distinct somatosensory modalities. Here, we coupled a novel behavioral approach with chronic extracellular electrophysiology to investigate differences in S1 gamma band activity elicited by noxious and innocuous hind paw stimulation in transgenic mice. Like prior studies, we found that trial-averaged gamma power in S1 increased following both noxious and innocuous stimuli. However, on individual trials, we noticed that evoked gamma band activity was not a continuous oscillatory signal but a series of transient spectral events. Upon further analysis we found that there was a significantly higher incidence of these gamma band events following noxious stimulation than innocuous stimulation. These findings suggest that somatosensory stimuli may be represented by specific features of gamma band activity at the single trial level, which may provide insight to mechanisms underlying acute pain.
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17
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Smith KM, Nguyen E, Ross SE. The Delta-Opioid Receptor Bidirectionally Modulates Itch. J Pain 2023; 24:264-272. [PMID: 36464136 PMCID: PMC10866011 DOI: 10.1016/j.jpain.2022.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 12/05/2022]
Abstract
Opioid signaling has been shown to be critically important in the neuromodulation of sensory circuits in the superficial spinal cord. Agonists of the mu-opioid receptor (MOR) elicit itch, whereas agonists of the kappa-opioid receptor (KOR) have been shown to inhibit itch. Despite the clear roles of MOR and KOR for the modulation itch, whether the delta-opioid receptor (DOR) is involved in the regulation of itch remained unknown. Here, we show that intrathecal administration of DOR agonists suppresses chemical itch and that intrathecal application of DOR antagonists is sufficient to evoke itch. We identify that spinal enkephalin neurons co-express neuropeptide Y (NPY), a peptide previously implicated in the inhibition of itch. In the spinal cord, DOR overlapped with both the NPY receptor (NPY1R) and KOR, suggesting that DOR neurons represent a site for convergent itch information in the dorsal horn. Lastly, we found that neurons co-expressing DOR and KOR showed significant Fos induction following pruritogen-evoked itch. These results uncover a role for DOR in the modulation of itch in the superficial dorsal horn. PERSPECTIVE: This article reveals the role of the delta-opioid receptor in itch. Intrathecal administration of delta agonists suppresses itch whereas the administration of delta antagonists is sufficient to induce itch. These studies highlight the importance of delta-opioid signaling for the modulation of itch behaviors, which may represent new targets for the management of itch disorders.
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Affiliation(s)
- Kelly M Smith
- University of Pittsburgh School of Medicine, Department of Neurobiology,Pittsburgh, Pennsylvania; University of Pittsburgh, Pittsburgh Center for Pain Research, Pittsburgh, Pennsylvania
| | - Eileen Nguyen
- University of Pittsburgh School of Medicine, Department of Neurobiology,Pittsburgh, Pennsylvania; University of Pittsburgh, Pittsburgh Center for Pain Research, Pittsburgh, Pennsylvania; University of Pittsburgh School of Medicine, Medical Scientist Training Program, Pittsburgh, Pennsylvania
| | - Sarah E Ross
- University of Pittsburgh School of Medicine, Department of Neurobiology,Pittsburgh, Pennsylvania; University of Pittsburgh, Pittsburgh Center for Pain Research, Pittsburgh, Pennsylvania.
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18
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Yang N, Shao H, Deng J, Yang Y, Tang Z, Wu G, Liu Y. Dictamnine ameliorates chronic itch in DNFB-induced atopic dermatitis mice via inhibiting MrgprA3. Biochem Pharmacol 2023; 208:115368. [PMID: 36493846 DOI: 10.1016/j.bcp.2022.115368] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
Chronic itch is the most prominent feature of atopic dermatitis (AD), and antihistamine treatment is often less effective in reducing clinical pruritus severity in AD. Multiple studies have shown that histamine-independent itch pathway is thought to predominate in AD-induced chronic itch. Mas-related G-protein-coupled receptor (Mrgpr) A3+ sensory neurons have been identified as one of the major itch-sensing neuron populations, and transient receptor potential (TRP) channel A1 is the key downstream of MrgprA3-mediated histamine-independent itch. MrgprA3-TRPA1 signal pathway is necessary for the development of chronic itch and may be the potentially promising target of chronic itch in AD. Dictamnine is one of the main quinoline alkaloid components of Cortex Dictamni (a traditional Chinese medicine widely used in clinical treatment of skin diseases). However, the anti-inflammatory and anti-pruritic effect of dictamnine on AD have not been reported. In this study, we used the 2,4-dinitrofluorobenzene (DNFB)-induced AD mouse model to observe the scratching behavior, inflammatory manifestations, and to detect the expression of MrgprA3 and TRPA1 in skin and DRG. The data demonstrated that dictamnine effectively inhibited AD-induced chronic itch, inflammation symptoms, epidermal thickening, inflammatory cell infiltration, and downregulated the expression of MrgprA3 and TRPA1. Furthermore, dictamnine restrained the excitability of MrgprA3+ and TRPA1+ neurons. Molecular docking also indicated that dictamnine has better binding affinity with MrgprA3. These results suggest that dictamnine may inhibit chronic itch caused by AD through the MrgprA3-TRPA1 mediated histamine-independent itch pathway, and may have a potential utility in AD treatment.
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Affiliation(s)
- Niuniu Yang
- Department of Traditional Chinese and Western Medicine, Medical College, Yangzhou University, Yangzhou 225009, China; The Key Laboratory of Syndrome Differentiation and Treatment of Gastric Cancer of the State Administration of Traditional Chinese Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225002, China.
| | - Haifeng Shao
- Department of Traditional Chinese and Western Medicine, Medical College, Yangzhou University, Yangzhou 225009, China; The Key Laboratory of Syndrome Differentiation and Treatment of Gastric Cancer of the State Administration of Traditional Chinese Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225002, China
| | - Jialin Deng
- Department of Traditional Chinese and Western Medicine, Medical College, Yangzhou University, Yangzhou 225009, China; The Key Laboratory of Syndrome Differentiation and Treatment of Gastric Cancer of the State Administration of Traditional Chinese Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225002, China
| | - Yan Yang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China; Key Laboratory for Chinese Medicine of Prevention and Treatment in Neurological Diseases, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Zongxiang Tang
- School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China; Key Laboratory for Chinese Medicine of Prevention and Treatment in Neurological Diseases, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Guanyi Wu
- College of Basic Medicine, Guangxi University of Chinese Medicine, Nanning 530299, China
| | - Yanqing Liu
- Department of Traditional Chinese and Western Medicine, Medical College, Yangzhou University, Yangzhou 225009, China; The Key Laboratory of Syndrome Differentiation and Treatment of Gastric Cancer of the State Administration of Traditional Chinese Medicine, Yangzhou University, Yangzhou 225009, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225002, China
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19
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Liu Y, Liu Y, Limjunyawong N, Narang C, Jamaldeen H, Yu S, Patiram S, Nie H, Caterina MJ, Dong X, Qu L. Sensory neuron-expressed TRPC3 mediates acute and chronic itch. Pain 2023; 164:98-110. [PMID: 35507377 DOI: 10.1097/j.pain.0000000000002668] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/20/2022] [Indexed: 01/09/2023]
Abstract
ABSTRACT Chronic pruritus is a prominent symptom of allergic contact dermatitis (ACD) and represents a huge unmet health problem. However, its underlying cellular and molecular mechanisms remain largely unexplored. TRPC3 is highly expressed in primary sensory neurons and has been implicated in peripheral sensitization induced by proinflammatory mediators. Yet, the role of TRPC3 in acute and chronic itch is still not well defined. Here, we show that, among mouse trigeminal ganglion (TG) neurons, Trpc3 mRNA is predominantly expressed in nonpeptidergic small diameter TG neurons of mice. Moreover, Trpc3 mRNA signal was present in most presumptively itch sensing neurons. TRPC3 agonism induced TG neuronal activation and acute nonhistaminergic itch-like and pain-like behaviors in naive mice. In addition, genetic deletion of Trpc3 attenuated acute itch evoked by certain common nonhistaminergic pruritogens, including endothelin-1 and SLIGRL-NH2. In a murine model of contact hypersensitivity (CHS), the Trpc3 mRNA expression level and function were upregulated in the TG after CHS. Pharmacological inhibition and global knockout of Trpc3 significantly alleviated spontaneous scratching behaviors without affecting concurrent cutaneous inflammation in the CHS model. Furthermore, conditional deletion of Trpc3 in primary sensory neurons but not in keratinocytes produced similar antipruritic effects in this model. These findings suggest that TRPC3 expressed in primary sensory neurons may contribute to acute and chronic itch through a histamine independent mechanism and that targeting neuronal TRPC3 might benefit the treatment of chronic itch associated with ACD and other inflammatory skin disorders.
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20
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Ganley RP, de Sousa MM, Werder K, Öztürk T, Mendes R, Ranucci M, Wildner H, Zeilhofer HU. Targeted anatomical and functional identification of antinociceptive and pronociceptive serotonergic neurons that project to the spinal dorsal horn. eLife 2023; 12:78689. [PMID: 36752606 PMCID: PMC9943064 DOI: 10.7554/elife.78689] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 02/06/2023] [Indexed: 02/09/2023] Open
Abstract
Spinally projecting serotonergic neurons play a key role in controlling pain sensitivity and can either increase or decrease nociception depending on physiological context. It is currently unknown how serotonergic neurons mediate these opposing effects. Utilizing virus-based strategies and Tph2-Cre transgenic mice, we identified two anatomically separated populations of serotonergic hindbrain neurons located in the lateral paragigantocellularis (LPGi) and the medial hindbrain, which respectively innervate the superficial and deep spinal dorsal horn and have contrasting effects on sensory perception. Our tracing experiments revealed that serotonergic neurons of the LPGi were much more susceptible to transduction with spinally injected AAV2retro vectors than medial hindbrain serotonergic neurons. Taking advantage of this difference, we employed intersectional chemogenetic approaches to demonstrate that activation of the LPGi serotonergic projections decreases thermal sensitivity, whereas activation of medial serotonergic neurons increases sensitivity to mechanical von Frey stimulation. Together these results suggest that there are functionally distinct classes of serotonergic hindbrain neurons that differ in their anatomical location in the hindbrain, their postsynaptic targets in the spinal cord, and their impact on nociceptive sensitivity. The LPGi neurons that give rise to rather global and bilateral projections throughout the rostrocaudal extent of the spinal cord appear to be ideally poised to contribute to widespread systemic pain control.
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Affiliation(s)
- Robert Philip Ganley
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | | | - Kira Werder
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | - Tugce Öztürk
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | - Raquel Mendes
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | - Matteo Ranucci
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | - Hendrik Wildner
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland
| | - Hanns Ulrich Zeilhofer
- Institute for Pharmacology and Toxicology, University of ZurichZurichSwitzerland,Institute of Pharmaceutical Sciences, Swiss Federal Institute of TechnologyZurichSwitzerland
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21
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Mießner H, Seidel J, Smith ESJ. In vitro models for investigating itch. Front Mol Neurosci 2022; 15:984126. [PMID: 36385768 PMCID: PMC9644192 DOI: 10.3389/fnmol.2022.984126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/10/2022] [Indexed: 12/04/2022] Open
Abstract
Itch (pruritus) is a sensation that drives a desire to scratch, a behavior observed in many animals. Although generally short-lasting and not causing harm, there are several pathological conditions where chronic itch is a hallmark symptom and in which prolonged scratching can induce damage. Finding medications to counteract the sensation of chronic itch has proven difficult due to the molecular complexity that involves a multitude of triggers, receptors and signaling pathways between skin, immune and nerve cells. While much has been learned about pruritus from in vivo animal models, they have limitations that corroborate the necessity for a transition to more human disease-like models. Also, reducing animal use should be encouraged in research. However, conducting human in vivo experiments can also be ethically challenging. Thus, there is a clear need for surrogate models to be used in pre-clinical investigation of the mechanisms of itch. Most in vitro models used for itch research focus on the use of known pruritogens. For this, sensory neurons and different types of skin and/or immune cells are stimulated in 2D or 3D co-culture, and factors such as neurotransmitter or cytokine release can be measured. There are however limitations of such simplistic in vitro models. For example, not all naturally occurring cell types are present and there is also no connection to the itch-sensing organ, the central nervous system (CNS). Nevertheless, in vitro models offer a chance to investigate otherwise inaccessible specific cell–cell interactions and molecular pathways. In recent years, stem cell-based approaches and human primary cells have emerged as viable alternatives to standard cell lines or animal tissue. As in vitro models have increased in their complexity, further opportunities for more elaborated means of investigating itch have been developed. In this review, we introduce the latest concepts of itch and discuss the advantages and limitations of current in vitro models, which provide valuable contributions to pruritus research and might help to meet the unmet clinical need for more refined anti-pruritic substances.
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Affiliation(s)
- Hendrik Mießner
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- Dermatological Skin Care, Beiersdorf AG, Hamburg, Germany
| | - Judith Seidel
- Dermatological Skin Care, Beiersdorf AG, Hamburg, Germany
| | - Ewan St. John Smith
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Ewan St. John Smith,
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22
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Gazerani P. How Does Botulinum Toxin Inhibit Itch? Toxins (Basel) 2022; 14:toxins14100701. [PMID: 36287970 PMCID: PMC9610088 DOI: 10.3390/toxins14100701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 12/04/2022] Open
Abstract
Two decades after reports of the anti-pruritic effects of botulinum neurotoxins (BoNTs), there is still no approved product for the anti-itch indication of BoNTs, and most clinical case reports still focus on the off-label use of BoNTs for various itchy conditions. Few randomized clinical trials have been conducted with controversial results, and the beneficial effects of BoNTs against itch are mainly based on case studies and case series. These studies are valuable in presenting the potential application of BoNTs in chronic pruritic conditions, but due to the nature of these studies, they are categorized as providing lower levels of evidence or lower grades of recommendation. To obtain approval for the anti-pruritic indication of BoNTs, higher levels of evidence are required, which can be achieved through conducting large-scale and well-designed studies with proper control groups and established careful and reliable primary and secondary outcomes. In addition to clinical evidence, presenting the mechanism-based antipruritic action of BoNTs can potentially strengthen, accelerate, and facilitate the current efforts towards further investments in accelerating the field towards the potential approval of BoNTs for itchy conditions. This review, therefore, aimed to provide the state-of-the-art mechanisms underlying the anti-itch effect of BoNTs from basic studies that resemble various clinical conditions with itch as a hallmark. Evidence of the neuronal, glial, and immune modulatory actions of BoNTs in reducing the transmission of itch are presented, and future potential directions are outlined.
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Affiliation(s)
- Parisa Gazerani
- Department of Life Sciences and Health, Faculty of Health Sciences, Oslo Metropolitan University, 0130 Oslo, Norway; or
- Department of Health Science and Technology, Faculty of Medicine, Aalborg University, 9220 Aalborg East, Denmark
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23
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Ma X, Chen W, Yang NN, Wang L, Hao XW, Tan CX, Li HP, Liu CZ. Potential mechanisms of acupuncture for neuropathic pain based on somatosensory system. Front Neurosci 2022; 16:940343. [PMID: 36203799 PMCID: PMC9530146 DOI: 10.3389/fnins.2022.940343] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 08/29/2022] [Indexed: 12/04/2022] Open
Abstract
Neuropathic pain, caused by a lesion or disease of the somatosensory system, is common and distressing. In view of the high human and economic burden, more effective treatment strategies were urgently needed. Acupuncture has been increasingly used as an adjuvant or complementary therapy for neuropathic pain. Although the therapeutic effects of acupuncture have been demonstrated in various high-quality randomized controlled trials, there is significant heterogeneity in the underlying mechanisms. This review aimed to summarize the potential mechanisms of acupuncture on neuropathic pain based on the somatosensory system, and guided for future both foundational and clinical studies. Here, we argued that acupuncture may have the potential to inhibit neuronal activity caused by neuropathic pain, through reducing the activation of pain-related ion channels and suppressing glial cells (including microglia and astrocytes) to release inflammatory cytokines, chemokines, amongst others. Meanwhile, acupuncture as a non-pharmacologic treatment, may have potential to activate descending pain control system via increasing the level of spinal or brain 5-hydroxytryptamine (5-HT), norepinephrine (NE), and opioid peptides. And the types of endogenously opioid peptides was influenced by electroacupuncture-frequency. The cumulative evidence demonstrated that acupuncture provided an alternative or adjunctive therapy for neuropathic pain.
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Affiliation(s)
- Xin Ma
- School of Acupuncture-Moxibustion and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Wen Chen
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Na-Na Yang
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Lu Wang
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Xiao-Wan Hao
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Chun-Xia Tan
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
| | - Hong-Ping Li
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
- Hong-Ping Li,
| | - Cun-Zhi Liu
- School of Acupuncture-Moxibustion and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
- School of Acupuncture-Moxibustion and Tuina, International Acupuncture and Moxibustion Innovation Institute, Beijing University of Chinese Medicine, Beijing, China
- *Correspondence: Cun-Zhi Liu,
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24
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Kim SH, Woo J, Choi K, Choi M, Han K. Neural Information Processing and Computations of Two-Input Synapses. Neural Comput 2022; 34:2102-2131. [PMID: 36027799 DOI: 10.1162/neco_a_01534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 06/02/2022] [Indexed: 11/04/2022]
Abstract
Information processing in artificial neural networks is largely dependent on the nature of neuron models. While commonly used models are designed for linear integration of synaptic inputs, accumulating experimental evidence suggests that biological neurons are capable of nonlinear computations for many converging synaptic inputs via homo- and heterosynaptic mechanisms. This nonlinear neuronal computation may play an important role in complex information processing at the neural circuit level. Here we characterize the dynamics and coding properties of neuron models on synaptic transmissions delivered from two hidden states. The neuronal information processing is influenced by the cooperative and competitive interactions among synapses and the coherence of the hidden states. Furthermore, we demonstrate that neuronal information processing under two-input synaptic transmission can be mapped to linearly nonseparable XOR as well as basic AND/OR operations. In particular, the mixtures of linear and nonlinear neuron models outperform the fashion-MNIST test compared to the neural networks consisting of only one type. This study provides a computational framework for assessing information processing of neuron and synapse models that may be beneficial for the design of brain-inspired artificial intelligence algorithms and neuromorphic systems.
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Affiliation(s)
- Soon Ho Kim
- Laboratory of Computational Neurophysics, Convergence Research Center for Brain Science, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Junhyuk Woo
- Laboratory of Computational Neurophysics, Convergence Research Center for Brain Science, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
| | - Kiri Choi
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, South Korea
| | - MooYoung Choi
- Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 08826, South Korea
| | - Kyungreem Han
- Laboratory of Computational Neurophysics, Convergence Research Center for Brain Science, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, South Korea
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25
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Jiang S, Wang YS, Zheng XX, Zhao SL, Wang Y, Sun L, Chen PH, Zhou Y, Tin C, Li HL, Sui JF, Wu GY. Itch-specific neurons in the ventrolateral orbital cortex selectively modulate the itch processing. Sci Adv 2022; 8:eabn4408. [PMID: 35905177 PMCID: PMC9337765 DOI: 10.1126/sciadv.abn4408] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 06/16/2022] [Indexed: 05/31/2023]
Abstract
Itch is a cutaneous sensation that is critical in driving scratching behavior. The long-standing question of whether there are specific neurons for itch modulation inside the brain remains unanswered. Here, we report a subpopulation of itch-specific neurons in the ventrolateral orbital cortex (VLO) that is distinct from the pain-related neurons. Using a Tet-Off cellular labeling system, we showed that local inhibition or activation of these itch-specific neurons in the VLO significantly suppressed or enhanced itch-induced scratching, respectively, whereas the intervention did not significantly affect pain. Conversely, suppression or activation of pain-specific neurons in the VLO significantly affected pain but not itch. Moreover, fiber photometry and immunofluorescence verified that these itch- and pain-specific neurons are distinct in their functional activity and histological location. In addition, the downstream targets of itch- and pain-specific neurons were different. Together, the present study uncovers an important subpopulation of neurons in the VLO that specifically modulates itch processing.
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Affiliation(s)
- Shan Jiang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Yi-Song Wang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Xiao-Xia Zheng
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Shan-Lan Zhao
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Yi Wang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Lin Sun
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Peng-Hui Chen
- Department of Neurobiology, Army Medical University, Chongqing 400038, China
| | - Yi Zhou
- Department of Neurobiology, Army Medical University, Chongqing 400038, China
| | - Chung Tin
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong, SAR, People’s Republic of China
| | - Hong-Li Li
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Jian-Feng Sui
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Guang-Yan Wu
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
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26
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Abstract
Itch triggers scratching, a behavioural defence mechanism that aids in the removal of harmful irritants and parasites1. Chemical itch is triggered by many endogenous and exogenous cues, such as pro-inflammatory histamine, which is released during an allergic reaction1. Mechanical itch can be triggered by light sensations such as wool fibres or a crawling insect2. In contrast to chemical itch pathways, which have been extensively studied, the mechanisms that underlie the transduction of mechanical itch are largely unknown. Here we show that the mechanically activated ion channel PIEZO1 (ref. 3) is selectively expressed by itch-specific sensory neurons and is required for their mechanically activated currents. Loss of PIEZO1 function in peripheral neurons greatly reduces mechanically evoked scratching behaviours and both acute and chronic itch-evoked sensitization. Finally, mice expressing a gain-of-function Piezo1 allele4 exhibit enhanced mechanical itch behaviours. Our studies reveal the polymodal nature of itch sensory neurons and identify a role for PIEZO1 in the sensation of itch. Experiments in mice show that the mechanically activated ion channel PIEZO1 is expressed in itch-specific sensory neurons and has a role in transducing mechanical itch.
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27
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Liu Q, Mai L, Yang S, Jia S, Chu Y, He H, Fan W, Huang F. Transcriptional Alterations of Mouse Trigeminal Ganglion Neurons Following Orofacial Inflammation Revealed by Single-Cell Analysis. Front Cell Neurosci 2022; 16:885569. [PMID: 35722619 PMCID: PMC9200971 DOI: 10.3389/fncel.2022.885569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022] Open
Abstract
Orofacial inflammation leads to transcriptional alterations in trigeminal ganglion (TG) neurons. However, diverse alterations and regulatory mechanisms following orofacial inflammatory pain in different types of TG neurons remain unclear. Here, orofacial inflammation was induced by injection of complete Freund’s adjuvant (CFA) in mice. After 7 days, we performed single-cell RNA-sequencing on TG cells of mice from control and treatment groups. We identified primary sensory neurons, Schwann cells, satellite glial cells, oligodendrocyte-like cells, immune cells, fibroblasts, and endothelial cells in TG tissue. After principal component analysis and hierarchical clustering, we identified six TG neuronal subpopulations: peptidergic nociceptors (PEP1 and PEP2), non-peptidergic nociceptors (NP1 and NP2), C-fiber low-threshold mechanoreceptors (cLTMR) and myelinated neurons (Nefh-positive neurons, NF) based on annotated marker gene expression. We also performed differential gene expression analysis among TG neuronal subtypes, identifying several differential genes involved in the inflammatory response, neuronal excitability, neuroprotection, and metabolic processes. Notably, we identified several potential novel targets associated with pain modulation, including Arl6ip1, Gsk3b, Scn7a, and Zbtb20 in PEP1, Rgs7bp in PEP2, and Bhlha9 in cLTMR. The established protein–protein interaction network identified some hub genes, implying their critical involvement in regulating orofacial inflammatory pain. Our study revealed the heterogeneity of TG neurons and their diverse neuronal transcriptomic responses to orofacial inflammation, providing a basis for the development of therapeutic strategies for orofacial inflammatory pain.
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Affiliation(s)
- Qing Liu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Lijia Mai
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Shengyan Yang
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Shilin Jia
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Yanhao Chu
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Hongwen He
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
| | - Wenguo Fan
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- *Correspondence: Wenguo Fan,
| | - Fang Huang
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, China
- Fang Huang,
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28
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Dong CR, Zhang WJ, Luo HL. Association between P2X3 receptors and neuropathic pain: As a potential therapeutic target for therapy. Biomed Pharmacother 2022; 150:113029. [PMID: 35489283 DOI: 10.1016/j.biopha.2022.113029] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 11/02/2022] Open
Abstract
Neuropathic pain is a common clinical symptom of various diseases, and it seriously affects the physical and mental health of patients. Owing to the complex pathological mechanism of neuropathic pain, clinical treatment of pain is challenging. Therefore, there is growing interest among researchers to explore potential therapeutic strategies for neuropathic pain. A large number of studies have shown that development of neuropathic pain is related to nerve conduction and related signaling molecules. P2X3 receptors (P2X3R) are ATP-dependent ion channels that participate in the transmission of neural information and related signaling pathways, sensitize the central nervous system, and play a key role in the development of neuropathic pain. In this paper, we summarized the structure and biological characteristics of the P2X3R gene and discussed the role of P2X3R in the nervous system. Moreover, we outlined the related pathological mechanisms of pain and described the relationship between P2X3R and chronic pain to provide valuable information for development of novel treatment strategies for pain.
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Affiliation(s)
- Cai-Rong Dong
- The Second Affiliated Hospital, Nanchang University, Nanchang, Jiangxi 343000, China
| | - Wen-Jun Zhang
- The Second Affiliated Hospital, Nanchang University, Nanchang, Jiangxi 343000, China.
| | - Hong-Liang Luo
- The Second Affiliated Hospital, Nanchang University, Nanchang, Jiangxi 343000, China
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29
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Wang H, Chen W, Dong Z, Xing G, Cui W, Yao L, Zou WJ, Robinson HL, Bian Y, Liu Z, Zhao K, Luo B, Gao N, Zhang H, Ren X, Yu Z, Meixiong J, Xiong WC, Mei L. A novel spinal neuron connection for heat sensation. Neuron 2022; 110:2315-2333.e6. [PMID: 35561677 DOI: 10.1016/j.neuron.2022.04.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 03/14/2022] [Accepted: 04/19/2022] [Indexed: 12/30/2022]
Abstract
Heat perception enables acute avoidance responses to prevent tissue damage and maintain body thermal homeostasis. Unlike other modalities, how heat signals are processed in the spinal cord remains unclear. By single-cell gene profiling, we identified ErbB4, a transmembrane tyrosine kinase, as a novel marker of heat-sensitive spinal neurons in mice. Ablating spinal ErbB4+ neurons attenuates heat sensation. These neurons receive monosynaptic inputs from TRPV1+ nociceptors and form excitatory synapses onto target neurons. Activation of ErbB4+ neurons enhances the heat response, while inhibition reduces the heat response. We showed that heat sensation is regulated by NRG1, an activator of ErbB4, and it involves dynamic activity of the tyrosine kinase that promotes glutamatergic transmission. Evidence indicates that the NRG1-ErbB4 signaling is also engaged in hypersensitivity of pathological pain. Together, these results identify a spinal neuron connection consisting of ErbB4+ neurons for heat sensation and reveal a regulatory mechanism by the NRG1-ErbB4 signaling.
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Affiliation(s)
- Hongsheng Wang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wenbing Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zhaoqi Dong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Guanglin Xing
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wanpeng Cui
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Lingling Yao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Wen-Jun Zou
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Heath L Robinson
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Yaoyao Bian
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zhipeng Liu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Kai Zhao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Bin Luo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Nannan Gao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Hongsheng Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Xiao Ren
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Zheng Yu
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - James Meixiong
- Solomon H. Snyder Department of Neuroscience and Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH 44106, USA.
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30
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Abstract
Itch and pain are both unpleasant, but they are discrete sensations. Both of these
sensations are transmitted by C-fibers and processed in laminae I-II of the dorsal horn.
To examine whether pruriception modulates pain, we first confirmed the activation of cells
in the itch-related circuits that were positive for gastrin-releasing peptide (GRP) and
GRP receptor (GRPR) using a paw formalin injection model. This pain model with typical
biphasic pain behavior increased c-Fos but did not affect the expressions of
GRP and GRPR mRNAs in the dorsal horn. Using c-Fos
expression as a marker for activated cells, we confirmed that formalin injection increased
the number of cells double-labeled for c-Fos and GRP or GRPR in the dorsal horn. The
emergence of these neurons indicates the activation of itch-related circuits by acute pain
signals. The effect of an antagonist for a GRPR was examined in the paw formalin injection
model. Intrathecal chronic antagonization of spinal GRPR enhanced the onset of phase II of
paw formalin injection-induced pain behavior. Exogenous intrathecal GRP infusion to the
paw-formalin injection model not only showed significant reduction of pain behavior but
also increased c-Fos in the inhibitory neurons in the dorsal horn. The anti-nociceptive
effect of spinal GRP infusion was observed in the peripheral inflammation model (complete
Freund’s adjuvant injection model). In this study we suggest that painful stimuli
activated itch-related neuronal circuits and uncovered the spinal activation of the
itch-induced analgesic effect on acute and established inflammatory pain.
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Affiliation(s)
- Ayano Saeki
- Department of Anatomy and Neuroscience, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan.,Department of Anesthesiology and Pain Medicine, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan
| | - Hiroki Yamanaka
- Department of Anatomy and Neuroscience, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan
| | - Kimiko Kobayashi
- Department of Anatomy and Neuroscience, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan
| | - Masamichi Okubo
- Department of Anatomy and Neuroscience, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience, Faculty of Medicine, 12818Hyogo Medical University, Nishinomiya, Hyogo, Japan
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31
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Cohen M, Feldman-goriachnik R, Hanani M. Satellite Glial Cells and Neurons in Trigeminal Ganglia Are Altered in an Itch Model in Mice. Cells 2022; 11:886. [PMID: 35269508 PMCID: PMC8909456 DOI: 10.3390/cells11050886] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 02/04/2023] Open
Abstract
Itch (pruritus) is a common chronic condition with a lifetime prevalence of over 20%. The mechanisms underlying itch are poorly understood, and its therapy is difficult. There is recent evidence that following nerve injury or inflammation, intercellular communications in sensory ganglia are augmented, which may lead to abnormal neuronal activity, and hence to pain, but there is no information whether such changes take place in an itch model. We studied changes in neurons and satellite glial cells (SGCs) in trigeminal ganglia in an itch model in mice using repeated applications of 2,4,6-trinitro-1-chlorobenzene (TNCB) to the external ear over a period of 11 days. Treated mice showed augmented scratching behavior as compared with controls during the application period and for several days afterwards. Immunostaining for the activation marker glial fibrillary acidic protein in SGCs was greater by about 35% after TNCB application, and gap junction-mediated coupling between neurons increased from about 2% to 13%. The injection of gap junction blockers reduced scratching behavior, suggesting that gap junctions contribute to itch. Calcium imaging studies showed increased responses of SGCs to the pain (and presumed itch) mediator ATP. We conclude that changes in both neurons and SGCs in sensory ganglia may play a role in itch.
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32
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Cui L, Guo J, Cranfill SL, Gautam M, Bhattarai J, Olson W, Beattie K, Challis RC, Wu Q, Song X, Raabe T, Gradinaru V, Ma M, Liu Q, Luo W. Glutamate in primary afferents is required for itch transmission. Neuron 2022; 110:809-823.e5. [PMID: 34986325 DOI: 10.1016/j.neuron.2021.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/21/2021] [Accepted: 12/06/2021] [Indexed: 12/13/2022]
Abstract
Whether glutamate or itch-selective neurotransmitters are used to confer itch specificity is still under debate. We focused on an itch-selective population of primary afferents expressing MRGPRA3, which highly expresses Vglut2 and the neuropeptide neuromedin B (Nmb), to investigate this question. Optogenetic stimulation of MRGPRA3+ afferents triggers scratching and other itch-related avoidance behaviors. Using a combination of optogenetics, spinal cord slice recordings, Vglut2 conditional knockout mice, and behavior assays, we showed that glutamate is essential for MRGPRA3+ afferents to transmit itch. We further demonstrated that MRGPRA3+ afferents form monosynaptic connections with both NMBR+ and NMBR- neurons and that NMB and glutamate together can enhance the activity of NMBR+ spinal DH neurons. Moreover, Nmb in MRGPRA3+ afferents and NMBR+ DH neurons are required for chloroquine-induced scratching. Together, our results establish a new model in which glutamate is an essential neurotransmitter in primary afferents for itch transmission, whereas NMB signaling enhances its activities.
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33
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Ma Q. A functional subdivision within the somatosensory system and its implications for pain research. Neuron 2022; 110:749-769. [PMID: 35016037 PMCID: PMC8897275 DOI: 10.1016/j.neuron.2021.12.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/07/2021] [Accepted: 12/09/2021] [Indexed: 12/12/2022]
Abstract
Somatosensory afferents are traditionally classified by soma size, myelination, and their response specificity to external and internal stimuli. Here, we propose the functional subdivision of the nociceptive somatosensory system into two branches. The exteroceptive branch detects external threats and drives reflexive-defensive reactions to prevent or limit injury. The interoceptive branch senses the disruption of body integrity, produces tonic pain with strong aversive emotional components, and drives self-caring responses toward to the injured region to reduce suffering. The central thesis behind this functional subdivision comes from a reflection on the dilemma faced by the pain research field, namely, the use of reflexive-defensive behaviors as surrogate assays for interoceptive tonic pain. The interpretation of these assays is now being challenged by the discovery of distinct but interwoven circuits that drive exteroceptive versus interoceptive types of behaviors, with the conflation of these two components contributing partially to the poor translation of therapies from preclinical studies.
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Affiliation(s)
- Qiufu Ma
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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Graham RD, Sankarasubramanian V, Lempka SF. Dorsal Root Ganglion Stimulation for Chronic Pain: Hypothesized Mechanisms of Action. J Pain 2022; 23:196-211. [PMID: 34425252 PMCID: PMC8943693 DOI: 10.1016/j.jpain.2021.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/28/2021] [Accepted: 07/20/2021] [Indexed: 02/03/2023]
Abstract
Dorsal root ganglion stimulation (DRGS) is a neuromodulation therapy for chronic pain that is refractory to conventional medical management. Currently, the mechanisms of action of DRGS-induced pain relief are unknown, precluding both our understanding of why DRGS fails to provide pain relief to some patients and the design of neurostimulation technologies that directly target these mechanisms to maximize pain relief in all patients. Due to the heterogeneity of sensory neurons in the dorsal root ganglion (DRG), the analgesic mechanisms could be attributed to the modulation of one or many cell types within the DRG and the numerous brain regions that process sensory information. Here, we summarize the leading hypotheses of the mechanisms of DRGS-induced analgesia, and propose areas of future study that will be vital to improving the clinical implementation of DRGS. PERSPECTIVE: This article synthesizes the evidence supporting the current hypotheses of the mechanisms of action of DRGS for chronic pain and suggests avenues for future interdisciplinary research which will be critical to fully elucidate the analgesic mechanisms of the therapy.
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Affiliation(s)
- Robert D. Graham
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States,Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, United States
| | - Vishwanath Sankarasubramanian
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States,Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, United States
| | - Scott F. Lempka
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, United States,Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, United States,Department of Anesthesiology, University of Michigan, Ann Arbor, MI 48109, United States,Corresponding author: Scott F. Lempka, PhD, Department of Biomedical Engineering, University of Michigan, 2800 Plymouth Road, NCRC 14-184, Ann Arbor, MI 48109-2800,
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Van Remoortel S, Timmermans JP. Mas-Related G Protein-Coupled Receptors (Mrgprs) as Mediators of Gut Neuro-Immune Signaling. Adv Exp Med Biol 2022; 1383:259-69. [PMID: 36587165 DOI: 10.1007/978-3-031-05843-1_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Over the past 15 years, the research field on Mas-related G protein-coupled receptors (Mrgprs), a relatively new family of rhodopsin A-like G protein-coupled receptors, has expanded enormously, and a plethora of recent studies have provided evidence that several of these Mrgpr family members play an important role in the underlying mechanisms of itch and pain, as well as in the initiation and modulation of inflammatory/allergic responses. Initial studies mainly focused on the skin, but more recently also visceral organs such as the respiratory and gastrointestinal (GI) tracts emerged as sites for Mrgpr involvement. It has become clear that the gastrointestinal tract and its innervation in close association with the immune system represent a novel expression site for Mrgprs where they contribute to the interoceptive mechanisms maintaining homeostasis and might constitute promising targets in chronic abdominal pain disorders. In this short review, we provide an update of our current knowledge on the expression, distribution, and function of members of this Mrgpr family in intrinsic and extrinsic neuro-immune pathways related to the gastrointestinal tract, their mediatory role(s) in gut neuro-immune signaling, and their involvement in visceral afferent (nociceptive) pathways.
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Chen XJ, Liu YH, Xu NL, Sun YG. Itch perception is reflected by neuronal ignition in the primary somatosensory cortex. Natl Sci Rev 2021; 9:nwab218. [PMID: 35769233 PMCID: PMC9232292 DOI: 10.1093/nsr/nwab218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 11/26/2021] [Accepted: 11/26/2021] [Indexed: 11/19/2022] Open
Abstract
Multiple cortical areas including the primary somatosensory cortex (S1) are activated during itch signal processing, yet cortical representation of itch perception remains unknown. Using novel miniature two-photon microscopic imaging in free-moving mice, we investigated the coding of itch perception in S1. We found that pharmacological inactivation of S1 abolished itch-induced scratching behavior, and the itch-induced scratching behavior could be well predicted by the activity of a fraction of layer 2/3 pyramidal neurons, suggesting that a subpopulation of S1 pyramidal neurons encoded itch perception, as indicated by immediate subsequent scratching behaviors. With a newly established optogenetics-based paradigm that allows precisely controlled pruritic stimulation, we found that a small fraction of S1 neurons exhibited an ignition-like pattern at the detection threshold of itch perception. Our study revealed the neural mechanism underlying itch perceptual coding in S1, thus paving the way for the study of cortical representation of itch perception at the single-neuron level in freely moving animals.
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Affiliation(s)
- Xiao-Jun Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan-He Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ning-Long Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
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Singleton H, Hodder A, Boyers D, Doney L, Almilaji O, Heaslip V, Thompson AR, Boyle RJ, Axon E, Van Onselen J, O'Meara S, Roberts A, Ersser SJ. Psychological and educational interventions for managing eczema. Hippokratia 2021. [DOI: 10.1002/14651858.cd014932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Heidi Singleton
- Department of Nursing Science; Bournemouth University; Bournemouth UK
| | - Andrew Hodder
- Department of Dermatology; Royal Cornwall Hospitals NHS Trust; Truro UK
- Department of Dermatology; University Hospitals Dorset; Christchurch UK
| | - Dwayne Boyers
- Health Economics Research Unit; University of Aberdeen; Aberdeen UK
| | - Liz Doney
- Cochrane Skin, Centre of Evidence Based Dermatology; University of Nottingham; Nottingham UK
| | - Orouba Almilaji
- Department of Medical Science and Public Health; Bournemouth University; Bournemouth UK
| | - Vanessa Heaslip
- Department of Nursing Science; Bournemouth University; Bournemouth UK
| | - Andrew R Thompson
- South Wales Clinical Psychology Training Programme; Cardiff and Vale University Health Board & Cardiff University; Cardiff UK
| | - Robert J Boyle
- Cochrane Skin, Centre of Evidence Based Dermatology; University of Nottingham; Nottingham UK
- National Heart & Lung Institute, Section of Inflammation and Repair; Imperial College London; London UK
| | - Emma Axon
- Cochrane Skin, Centre of Evidence Based Dermatology; University of Nottingham; Nottingham UK
| | | | | | - Amanda Roberts
- Nottingham Support Group for Carers of Children with Eczema; Nottingham UK
| | - Steven J Ersser
- Department of Nursing Science; Bournemouth University; Bournemouth UK
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Yang T, Yuan Z, Liu C, Liu T, Zhang W. A neural circuit integrates pharyngeal sensation to control feeding. Cell Rep 2021; 37:109983. [PMID: 34758309 DOI: 10.1016/j.celrep.2021.109983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 08/20/2021] [Accepted: 10/20/2021] [Indexed: 11/18/2022] Open
Abstract
Swallowing is an essential step of eating and drinking. However, how the quality of a food bolus is sensed by pharyngeal neurons is largely unknown. Here we find that mechanical receptors along the Drosophila pharynx are required for control of meal size, especially for food of high viscosity. The mechanical force exerted by the bolus passing across the pharynx is detected by neurons expressing the mechanotransduction channel NOMPC (no mechanoreceptor potential C) and is relayed, together with gustatory information, to IN1 neurons in the subesophageal zone (SEZ) of the brain. IN1 (ingestion neurons) neurons act directly upstream of a group of peptidergic neurons that encode satiety. Prolonged activation of IN1 neurons suppresses feeding. IN1 neurons receive inhibition from DSOG1 (descending subesophageal neurons) neurons, a group of GABAergic neurons that non-selectively suppress feeding. Our results reveal the function of pharyngeal mechanoreceptors and their downstream neural circuits in the control of food ingestion.
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Affiliation(s)
- Tingting Yang
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Zixuan Yuan
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Chenxi Liu
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Ting Liu
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Wei Zhang
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Beijing 100084, China.
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Mecum NE, Russell R, Lee J, Sullivan C, Meng ID. Optogenetic Inhibition of Nav1.8 Expressing Corneal Afferents Reduces Persistent Dry Eye Pain. Invest Ophthalmol Vis Sci 2021; 62:15. [PMID: 34787642 PMCID: PMC8606841 DOI: 10.1167/iovs.62.14.15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The aim of the present study was to investigate the contribution of Nav1.8 expressing corneal afferent neurons to the presence of ongoing pain in lacrimal gland excision (LGE)-induced dry eye. Methods The proton pump archaerhodopsin-3/eGFP (ArchT/eGFP) was conditionally expressed in corneal afferents using Nav1.8-cre mice. Dry eye was produced by unilateral LGE. Real time place preference was assessed using a three-chamber apparatus. A neutral, unlit center chamber was flanked by one illuminated with a control light and one illuminated with an ArchT activating light. For real-time preference, animals were placed in the neutral chamber and tracked over five 10-minute sessions, with the lights turned on during the second and fourth sessions. In other studies, movement was tracked over three 10-minute sessions (the lights turned on only during the second session), with animals tested once per day over the course of 4 days. A local anesthetic was used to examine the role of ongoing corneal afferent activity in producing place preference. Results The corneal afferent nerves and trigeminal ganglion cell bodies showed a robust eGFP signal in Nav1.8-cre;ArchT/eGFP mice. After LGE, Nav1.8-cre;ArchT/eGFP mice demonstrated a preference for the ArchT activating light paired chamber. Preference was prevented with pre-application to the cornea of a local anesthetic. Nav1.8-cre;ArchT/eGFP mice with sham surgery and LGE wild-type control mice did not develop preference. Conclusions Results indicate LGE-induced persistent, ongoing pain, driven by Nav1.8 expressing corneal afferents. Inhibition of these neurons represents a potential strategy for treating ongoing dry eye-induced pain.
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Affiliation(s)
- Neal E Mecum
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Molecular and Biomedical Sciences, University of Maine, Orono, Maine, United States
| | - Rachel Russell
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States
| | - Jun Lee
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Department of Complete Denture Prosthodontics, School of Dentistry, Nihon University, Tokyo, Japan
| | - Cara Sullivan
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine, Orono, Maine, United States
| | - Ian D Meng
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Graduate Studies in Biomedical Sciences and Engineering, University of Maine, Orono, Maine, United States.,Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine, United States
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Abstract
Itch is one of the most primal sensations, being both ubiquitous and important for the well-being of animals. For more than a century, a desire to understand how itch is encoded by the nervous system has prompted the advancement of many theories. Within the past 15 years, our understanding of the molecular and neural mechanisms of itch has undergone a major transformation, and this remarkable progress continues today without any sign of abating. Here I describe accumulating evidence that indicates that itch is distinguished from pain through the actions of itch-specific neuropeptides that relay itch information to the spinal cord. According to this model, classical neurotransmitters transmit, inhibit and modulate itch information in a context-, space- and time-dependent manner but do not encode itch specificity. Gastrin-releasing peptide (GRP) is proposed to be a key itch-specific neuropeptide, with spinal neurons expressing GRP receptor (GRPR) functioning as a key part of a convergent circuit for the conveyance of peripheral itch information to the brain.
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Warwick C, Cassidy C, Hachisuka J, Wright MC, Baumbauer KM, Adelman PC, Lee KH, Smith KM, Sheahan TD, Ross SE, Koerber HR. MrgprdCre lineage neurons mediate optogenetic allodynia through an emergent polysynaptic circuit. Pain 2021; 162:2120-2131. [PMID: 34130311 PMCID: PMC8206522 DOI: 10.1097/j.pain.0000000000002227] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 12/14/2022]
Abstract
ABSTRACT Most cutaneous C fibers, including both peptidergic and nonpeptidergic subtypes, are presumed to be nociceptors and respond to noxious input in a graded manner. However, mechanically sensitive, nonpeptidergic C fibers also respond to mechanical input in the innocuous range, so the degree to which they contribute to nociception remains unclear. To address this gap, we investigated the function of nonpeptidergic afferents using the MrgprdCre allele. In real-time place aversion studies, we found that low-frequency optogenetic activation of MrgrpdCre lineage neurons was not aversive in naive mice but became aversive after spared nerve injury (SNI). To address the underlying mechanisms of this allodynia, we recorded responses from lamina I spinoparabrachial (SPB) neurons using the semi-intact ex vivo preparation. After SNI, innocuous brushing of the skin gave rise to abnormal activity in lamina I SPB neurons, consisting of an increase in the proportion of recorded neurons that responded with excitatory postsynaptic potentials or action potentials. This increase was likely due, at least in part, to an increase in the proportion of lamina I SPB neurons that received input on optogenetic activation of MrgprdCre lineage neurons. Intriguingly, in SPB neurons, there was a significant increase in the excitatory postsynaptic current latency from MrgprdCre lineage input after SNI, consistent with the possibility that the greater activation post-SNI could be due to the recruitment of a new polysynaptic circuit. Together, our findings suggest that MrgprdCre lineage neurons can provide mechanical input to the dorsal horn that is nonnoxious before injury but becomes noxious afterwards because of the engagement of a previously silent polysynaptic circuit in the dorsal horn.
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Affiliation(s)
- Charles Warwick
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Colleen Cassidy
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Junichi Hachisuka
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
- Spinal Cord Group, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Margaret C. Wright
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kyle M. Baumbauer
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, MO, United States
| | - Peter C. Adelman
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kuan H. Lee
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kelly M. Smith
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Tayler D. Sheahan
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Sarah E. Ross
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - H. Richard Koerber
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, United States
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Düll MM, Stengel M, Ries V, Strupf M, Reeh PW, Kremer AE, Namer B. Lysophosphatidic acid activates nociceptors and causes pain or itch depending on the application mode in human skin. Pain 2021. [PMID: 34166323 DOI: 10.1097/j.pain.0000000000002363] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 04/13/2021] [Indexed: 11/26/2022]
Abstract
ABSTRACT Lysophosphatidic acid (LPA) is involved in the pathophysiology of cholestatic pruritus and neuropathic pain. Slowly conducting peripheral afferent C-nerve fibers are crucial in the sensations of itch and pain. In animal studies, specialized neurons ("pruriceptors") have been described, expressing specific receptors e.g. from the Mrgpr family. Human nerve fibers involved in pain signaling ("nociceptors") can elicit itch if activated by focalized stimuli such as cowhage spicules.In this study, we scrutinized the effects of LPA in humans by two different application modes on the level of psychophysics and single nerve fiber recordings (microneurography). In healthy human subjects, intracutaneous LPA microinjections elicited burning pain, whereas LPA application via inactivated cowhage spicules evoked a moderate itch sensation. LPA microinjections induced heat hyperalgesia and hypersensitivity to higher electrical stimulus frequencies. Pharmacological blockade of TRPA1 or TRPV1 reduced heat hyperalgesia but not acute chemical pain. Microneurography revealed an application mode-dependent differential activation of mechano-sensitive (CM) and mechano-insensitive (CMi) C-fibers. LPA microinjections activated a greater proportion of CMi and more strongly than CM fibers; spicule-application of LPA activated CM and CMi fibers to a similar extent but excited CM more and CMi fibers less intensely than microinjections.In conclusion, we show for the first time in humans that LPA can cause pain as well as itch dependent on the mode of application and activates afferent human C-fibers. Itch may arise from focal activation of few nerve fibers with distinct spatial contrast to unexcited surrounding afferents, and a specific combination of activated fiber subclasses might contribute.
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Dieckmann G, Borsook D, Moulton E. Neuropathic corneal pain and dry eye: a continuum of nociception. Br J Ophthalmol 2021; 106:1039-1043. [PMID: 33931393 DOI: 10.1136/bjophthalmol-2020-318469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/24/2022]
Abstract
Throughout the body, damage to peripheral nerves normally involved in nociception may produce a constellation of symptoms-including irritation, itchiness and pain. The neurobiological processes involved in corneal symptoms of dry eye (DE) and neuropathic corneal pain (NCP) have not been clearly considered in terms of nociceptive processing. The conventional underlying presumption is that a labelled line principle is responsible; that these distinct perceptions are hard coded by primary afferent inputs to the central nervous system. This presumption oversimplifies the neurobiological mechanisms underlying somatosensory perception. The labelled line perspective that DE represents a chronic pain condition does not make intuitive sense: how can an eye condition that is not painful in most cases be considered a pain condition? Does not chronic pain by definition require pain to be present? On the other hand, NCP, a term that clearly denotes a painful condition, has historically seemed to resonate with clinical significance. Both DE and NCP can share similar features, yet their differentiation is not always clear. As is often the case, clinical terms arise from different disciplines, with DE evolving from ophthalmological findings and NCP inspired by pain neurophysiology. This review evaluates the current definition of these terms, the rationale for their overlap and how the neurophysiology of itch impacts our understanding of these conditions as a continuum of the same disease. Despite the complexity of nociceptive physiology, an understanding of these mechanisms will allow us a more precise therapeutic approach.
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Affiliation(s)
- Gabriela Dieckmann
- Brain and Eye Pain Imaging Lab, Pain and Affective Neuroscience Center, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital/Harvard Medical School, Boston, Massachusetts, USA
| | - David Borsook
- Brain and Eye Pain Imaging Lab, Pain and Affective Neuroscience Center, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital/Harvard Medical School, Boston, Massachusetts, USA
| | - Eric Moulton
- Brain and Eye Pain Imaging Lab, Pain and Affective Neuroscience Center, Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children's Hospital/Harvard Medical School, Boston, Massachusetts, USA
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Steele HR, Xing Y, Zhu Y, Hilley HB, Lawson K, Nho Y, Niehoff T, Han L. MrgprC11 + sensory neurons mediate glabrous skin itch. Proc Natl Acad Sci U S A 2021; 118:e2022874118. [PMID: 33876765 DOI: 10.1073/pnas.2022874118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Itch arising from glabrous skin (palms and soles) has attracted limited attention within the field due to the lack of methodology. This is despite glabrous itch arising from many medical conditions such as plantar and palmar psoriasis, dyshidrosis, and cholestasis. Therefore, we developed a mouse glabrous skin behavioral assay to investigate the contribution of three previously identified pruriceptive neurons in glabrous skin itch. Our results show that MrgprA3+ and MrgprD+ neurons, although key mediators for hairy skin itch, do not play important roles in glabrous skin itch, demonstrating a mechanistic difference in itch sensation between hairy and glabrous skin. We found that MrgprC11+ neurons are the major mediators for glabrous skin itch. Activation of MrgprC11+ neurons induced glabrous skin itch, while ablation of MrgprC11+ neurons reduced both acute and chronic glabrous skin itch. Our study provides insights into the mechanisms of itch and opens up new avenues for future glabrous skin itch research.
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Abstract
Mechanistic theories of itch are based on neuronal specificity, stimulus intensity, and temporal or spatial discharge patterns. Traditionally, these theories are conceptualized as mutually exclusive, assuming that finding evidence for one theory would exclude the others and could sufficiently explain itch. Current experimental data primarily support the specificity or pattern theory of itch. However, in contrast to an assumed inherent exclusivity, recent results have shown that even within itch-specific pathways in the spinal cord, temporal discharge patterns are important as sustained pruriceptor is required to allow successful transsynaptic signal progression. Also, optogenetic activation of pruriceptors suggest that the combination of neuronal specificity and temporal pattern determines the sensory effect: tonic activation of pruriceptors is required to induce scratching behavior whereas short-lasting stimulation rather causes withdrawal. In addition to the mere duration of discharge, also the temporal pattern or spatial aspects could critically contribute to elicit pruritus instead of pain. Basic neurophysiological studies trying to validate neuronal theories for pruritus in their pure form provide unitary concepts leading from neuronal discharge to the itch sensation. However, the crucial clinical questions have the opposite perspective: which mechanisms explain the chronic itch in a given patient or a given disease? In trying to solve these clinical problems we should not feel bound to the mutual exclusive nature of itch theories, but rather appreciate blending several theories and also accept combinations of itch and pain. Thus, blended versions of itch theories might better suffice for an explanation of chronic itch in patients and will improve the basis for mechanistic treatment options.
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Affiliation(s)
- Martin Schmelz
- Department of Experimental Pain Research, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Kupari J, Usoskin D, Parisien M, Lou D, Hu Y, Fatt M, Lönnerberg P, Spångberg M, Eriksson B, Barkas N, Kharchenko PV, Loré K, Khoury S, Diatchenko L, Ernfors P. Single cell transcriptomics of primate sensory neurons identifies cell types associated with chronic pain. Nat Commun 2021; 12:1510. [PMID: 33686078 DOI: 10.1038/s41467-021-21725-z] [Citation(s) in RCA: 94] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 02/08/2021] [Indexed: 01/24/2023] Open
Abstract
Distinct types of dorsal root ganglion sensory neurons may have unique contributions to chronic pain. Identification of primate sensory neuron types is critical for understanding the cellular origin and heritability of chronic pain. However, molecular insights into the primate sensory neurons are missing. Here we classify non-human primate dorsal root ganglion sensory neurons based on their transcriptome and map human pain heritability to neuronal types. First, we identified cell correlates between two major datasets for mouse sensory neuron types. Machine learning exposes an overall cross-species conservation of somatosensory neurons between primate and mouse, although with differences at individual gene level, highlighting the importance of primate data for clinical translation. We map genomic loci associated with chronic pain in human onto primate sensory neuron types to identify the cellular origin of chronic pain. Genome-wide associations for chronic pain converge on two different neuronal types distributed between pain disorders that display different genetic susceptibilities, suggesting both unique and shared mechanisms between different pain conditions. The contribution of distinct types of dorsal root ganglion neurons to chronic pain is unclear. Here, the authors molecularly profile non-human primate sensory neurons and show that genome-wide associations converge on two neuronal types with different genetic susceptibilities for chronic pain.
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Hu Y, Shan WQ, Wu B, Liu T. New Insight into the Origins of Itch and Pain: How are Itch and Pain Signals Coded and Discriminated by Primary Sensory Neurons? Neurosci Bull 2021; 37:575-578. [PMID: 33683647 DOI: 10.1007/s12264-021-00643-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 09/28/2020] [Indexed: 10/22/2022] Open
Affiliation(s)
- Yue Hu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Wen-Qi Shan
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Bin Wu
- Institute of Pain Medicine and Special Environmental Medicine, Nantong University, Nantong, 226019, China
| | - Tong Liu
- Institute of Pain Medicine and Special Environmental Medicine, Nantong University, Nantong, 226019, China. .,College of Life Sciences, Yanan University, Yanan, 716000, China.
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Inclan-Rico JM, Kim BS, Abdus-Saboor I. Beyond somatosensation: Mrgprs in mucosal tissues. Neurosci Lett 2021; 748:135689. [PMID: 33582191 DOI: 10.1016/j.neulet.2021.135689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/11/2021] [Accepted: 01/19/2021] [Indexed: 11/29/2022]
Abstract
Mas-related G coupled receptors (Mrgprs) are a superfamily of receptors expressed in sensory neurons that are known to transmit somatic sensations from the skin to the central nervous system. Interestingly, Mrgprs have recently been implicated in sensory and motor functions of mucosal-associated neuronal circuits. The gastrointestinal and pulmonary tracts are constantly exposed to noxious stimuli. Therefore, it is likely that neuronal Mrgpr signaling pathways in mucosal tissues, akin to their family members expressed in the skin, might relay messages that alert the host when mucosal tissues are affected by damaging signals. Further, Mrgprs have been proposed to mediate the cross-talk between sensory neurons and immune cells that promotes host-protective functions at barrier sites. Although the mechanisms by which Mrgprs are activated in mucosal tissues are not completely understood, these exciting studies implicate Mrgprs as potential therapeutic targets for conditions affecting the intestinal and airway mucosa. This review will highlight the central role of Mrgpr signaling pathways in the regulation of homeostasis at mucosal tissues.
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Affiliation(s)
- Juan M Inclan-Rico
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA; Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian S Kim
- Division of Dermatology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA; Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO, USA.
| | - Ishmail Abdus-Saboor
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA.
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Abstract
Owing to their functional diversity, the Mas-related G-protein-coupled receptor (Mrgpr) family has a role in both itch and pain modulation. While primarily linked to pruritis, Mrgprs were originally characterized in small-diameter nociceptive neurons of dorsal root ganglia (DRG) and trigeminal ganglia. This review will focus on the role Mrgpr's have in pain physiology, discussing recent discoveries as well as how Mrgpr's may provide a new target for the treatment of pathological pain.
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Affiliation(s)
- Dustin P Green
- Department of Neuroscience, Cell Biology, & Anatomy, University of Texas Medical Branch, Galveston, TX, USA
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