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Zhang L, Nagel M, Olson WP, Chesler AT, O'Connor DH. Trigeminal innervation and tactile responses in mouse tongue. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.17.553449. [PMID: 37645855 PMCID: PMC10462066 DOI: 10.1101/2023.08.17.553449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The mammalian tongue is richly innervated with somatosensory, gustatory and motor fibers. These form the basis of many ethologically important functions such as eating, speaking and social grooming. Despite its high tactile acuity and sensitivity, the neural basis of tongue mechanosensation remains largely mysterious. Here we explored the organization of mechanosensory afferents in the tongue and found that each lingual papilla is innervated by Piezo2 + trigeminal neurons. Notably, each fungiform papilla contained highly specialized ring-like sensory neuron terminations that asymmetrically circumscribe the taste buds. Myelinated lingual afferents in the mouse lingual papillae did not form corpuscular sensory end organs but rather had only free nerve endings. In vivo single-unit recordings from the trigeminal ganglion revealed lingual low-threshold mechanoreceptors (LTMRs) with conduction velocities in the Aδ range or above and distinct adaptation properties ranging from intermediately adapting (IA) to rapidly adapting (RA). IA units were sensitive to both static indentation and stroking, while RA units had a preference for tangential forces applied by stroking. Lingual LTMRs were not directly responsive to rapid cooling or chemicals that can induce astringent or numbing sensations. Sparse labeling of lingual afferents in the tongue revealed distinct terminal morphologies and innervation patterns in fungiform and filiform papillae. Together, our results indicate that fungiform papillae are mechanosensory structures, while suggesting a simple model that links the functional and anatomical properties of tactile sensory neurons in the tongue.
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Zhang Y, Wu C, Jiang W, Cao Y, Chen D. VGLUT2 and APP family: unraveling the neurobiochemical mechanisms of neurostimulation therapy to STZ-induced diabetes and neuropathy. Front Endocrinol (Lausanne) 2024; 15:1336854. [PMID: 38370359 PMCID: PMC10869491 DOI: 10.3389/fendo.2024.1336854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 01/17/2024] [Indexed: 02/20/2024] Open
Abstract
Diabetic Peripheral Neuropathy (DPN) poses an escalating threat to public health, profoundly impacting well-being and quality of life. Despite its rising prevalence, the pathogenesis of DPN remains enigmatic, and existing clinical interventions fall short of achieving meaningful reversals of the condition. Notably, neurostimulation techniques have shown promising efficacy in alleviating DPN symptoms, underscoring the imperative to elucidate the neurobiochemical mechanisms underlying DPN. This study employs an integrated multi-omics approach to explore DPN and its response to neurostimulation therapy. Our investigation unveiled a distinctive pattern of vesicular glutamate transporter 2 (VGLUT2) expression in DPN, rigorously confirmed through qPCR and Western blot analyses in DPN C57 mouse model induced by intraperitoneal Streptozotocin (STZ) injection. Additionally, combining microarray and qPCR methodologies, we revealed and substantiated variations in the expression of the Amyloid Precursor Protein (APP) family in STZ-induced DPN mice. Analyzing the transcriptomic dataset generated from neurostimulation therapy for DPN, we intricately explored the differential expression patterns of VGLUT2 and APPs. Through correlation analysis, protein-protein interaction predictions, and functional enrichment analyses, we predicted the key biological processes involving VGLUT2 and the APP family in the pathogenesis of DPN and during neurostimulation therapy. This comprehensive study not only advances our understanding of the pathogenesis of DPN but also provides a theoretical foundation for innovative strategies in neurostimulation therapy for DPN. The integration of multi-omics data facilitates a holistic view of the molecular intricacies of DPN, paving the way for more targeted and effective therapeutic interventions.
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Affiliation(s)
- Yitong Zhang
- School of Medical Technology, Beijing Institute of Technology, Beijing, China
| | - Chenxuan Wu
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Wenqi Jiang
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yan Cao
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Dongtai Chen
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, China
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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] [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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MacDonald DI, Jayabalan M, Seaman J, Nickolls A, Chesler A. Pain persists in mice lacking both Substance P and CGRPα signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.15.567208. [PMID: 38076807 PMCID: PMC10705526 DOI: 10.1101/2023.11.15.567208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
The neuropeptides Substance P and CGRPα have long been thought important for pain sensation. Both peptides and their receptors are expressed at high levels in pain-responsive neurons from the periphery to the brain making them attractive therapeutic targets. However, drugs targeting these pathways individually did not relieve pain in clinical trials. Since Substance P and CGRPα are extensively co-expressed we hypothesized that their simultaneous inhibition would be required for effective analgesia. We therefore generated Tac1 and Calca double knockout (DKO) mice and assessed their behavior using a wide range of pain-relevant assays. As expected, Substance P and CGRPα peptides were undetectable throughout the nervous system of DKO mice. To our surprise, these animals displayed largely intact responses to mechanical, thermal, chemical, and visceral pain stimuli, as well as itch. Moreover, chronic inflammatory pain and neurogenic inflammation were unaffected by loss of the two peptides. Finally, neuropathic pain evoked by nerve injury or chemotherapy treatment was also preserved in peptide-deficient mice. Thus, our results demonstrate that even in combination, Substance P and CGRPα are not required for the transmission of acute and chronic pain.
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Affiliation(s)
- Donald Iain MacDonald
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, United States
| | - Monessha Jayabalan
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, United States
| | - Jonathan Seaman
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, United States
| | - Alec Nickolls
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, United States
| | - Alexander Chesler
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, United States
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
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Liu AR, Lin ZJ, Wei M, Tang Y, Zhang H, Peng XG, Li Y, Zheng YF, Tan Z, Zhou LJ, Feng X. The potent analgesia of intrathecal 2R, 6R-HNK via TRPA1 inhibition in LF-PENS-induced chronic primary pain model. J Headache Pain 2023; 24:141. [PMID: 37858040 PMCID: PMC10585932 DOI: 10.1186/s10194-023-01667-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023] Open
Abstract
BACKGROUND Chronic primary pain (CPP) is an intractable pain of unknown cause with significant emotional distress and/or dysfunction that is a leading factor of disability globally. The lack of a suitable animal model that mimic CPP in humans has frustrated efforts to curb disease progression. 2R, 6R-hydroxynorketamine (2R, 6R-HNK) is the major antidepressant metabolite of ketamine and also exerts antinociceptive action. However, the analgesic mechanism and whether it is effective for CPP are still unknown. METHODS Based on nociplastic pain is evoked by long-term potentiation (LTP)-inducible high- or low-frequency electrical stimulation (HFS/LFS), we wanted to develop a novel CPP mouse model with mood and cognitive comorbidities by noninvasive low-frequency percutaneous electrical nerve stimulation (LF-PENS). Single/repeated 2R, 6R-HNK or other drug was intraperitoneally (i.p.) or intrathecally (i.t.) injected into naïve or CPP mice to investigate their analgesic effect in CPP model. A variety of behavioral tests were used to detect the changes in pain, mood and memory. Immunofluorescent staining, western blot, reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) and calcium imaging of in cultured dorsal root ganglia (DRG) neurons by Fluo-8-AM were used to elucidate the role and mechanisms of 2R, 6R-HNK in vivo or in vitro. RESULTS Intrathecal 2R, 6R-HNK, rather than intraperitoneal 2R, 6R-HNK or intrathecal S-Ketamine, successfully mitigated HFS-induced pain. Importantly, intrathecal 2R, 6R-HNK displayed effective relief of bilateral pain hypersensitivity and depressive and cognitive comorbidities in a dose-dependent manner in LF-PENS-induced CPP model. Mechanically, 2R, 6R-HNK markedly attenuated neuronal hyperexcitability and the upregulation of calcitonin gene-related peptide (CGRP), transient receptor potential ankyrin 1 (TRPA1) or vanilloid-1 (TRPV1), and vesicular glutamate transporter-2 (VGLUT2) in peripheral nociceptive pathway. In addition, 2R, 6R-HNK suppressed calcium responses and CGRP overexpression in cultured DRG neurons elicited by the agonists of TRPA1 or/and TRPV1. Strikingly, the inhibitory effects of 2R, 6R-HNK on these pain-related molecules and mechanical allodynia were substantially occluded by TRPA1 antagonist menthol. CONCLUSIONS In the newly designed CPP model, our findings highlighted the potential utility of intrathecal 2R, 6R-HNK for preventing and therapeutic modality of CPP. TRPA1-mediated uprgulation of CGRP and neuronal hyperexcitability in nociceptive pathways may undertake both unique characteristics and solving process of CPP.
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Affiliation(s)
- An-Ran Liu
- Department of Anesthesiology and Pain Clinic, First Affiliated Hospital of Sun Yat-Sen University, No.58, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Zhen-Jia Lin
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Ming Wei
- Department of Anesthesiology and Pain Clinic, First Affiliated Hospital of Sun Yat-Sen University, No.58, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Yuan Tang
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Hui Zhang
- Department of Anesthesiology, Guangdong Second Provincial General Hospital, No.466, Mid Xingang Road, Haizhu District, Guangzhou, 510317, China
| | - Xiang-Ge Peng
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Ying Li
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Yu-Fan Zheng
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China
| | - Zhi Tan
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China.
| | - Li-Jun Zhou
- Department of Physiology and Pain Research Center, Zhongshan School of Medicine, Guangdong Province Key Laboratory of Brain Function and Disease, Sun Yat-Sen University, No.74, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China.
| | - Xia Feng
- Department of Anesthesiology and Pain Clinic, First Affiliated Hospital of Sun Yat-Sen University, No.58, 2Nd Zhongshan Road, Yuexiu District, Guangzhou, 510080, China.
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Broadhead MJ, Ayvazian-Hancock A, Doucet K, Kantelberg O, Motherwell L, Zhu F, Grant SGN, Horrocks MH, Miles GB. Synaptic expression of TAR-DNA-binding protein 43 in the mouse spinal cord determined using super-resolution microscopy. Front Mol Neurosci 2023; 16:1027898. [PMID: 37671010 PMCID: PMC10475998 DOI: 10.3389/fnmol.2023.1027898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 06/22/2023] [Indexed: 09/07/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is characterised by a loss of motor neurons in the brain and spinal cord that is preceded by early-stage changes in synapses that may be associated with TAR-DNA-Binding Protein 43 (TDP-43) pathology. Cellular inclusions of hyperphosphorylated TDP-43 (pTDP-43) are a key hallmark of neurodegenerative diseases such ALS. However, there has been little characterisation of the synaptic expression of TDP-43 inside subpopulations of spinal cord synapses. This study utilises a range of high-resolution and super-resolution microscopy techniques with immunolabelling, as well as an aptamer-based TDP-43 labelling strategy visualised with single-molecule localisation microscopy, to characterise and quantify the presence of pTDP-43 in populations of excitatory synapses near where motor neurons reside in the lateral ventral horn of the mouse lumbar spinal cord. We observe that TDP-43 is expressed in approximately half of spinal cord synapses as nanoscale clusters. Synaptic TDP-43 clusters are found most abundantly at synapses associated with VGLUT1-positive presynaptic terminals, compared to VGLUT2-associated synapses. Our nanoscopy techniques showed no difference in the subsynaptic expression of pTDP-43 in the ALS mouse model, SOD1G93a, compared to healthy controls, despite prominent structural deficits in VGLUT1-associated synapses in SOD1G93a mice. This research characterises the basic synaptic expression of TDP-43 with nanoscale precision and provides a framework with which to investigate the potential relationship between TDP-43 pathology and synaptic pathology in neurodegenerative diseases.
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Affiliation(s)
- Matthew J. Broadhead
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
- Centre of Biophotonics, University of St. Andrews, St. Andrews, United Kingdom
- Edinburgh Super-Resolution Imaging Consortium, Heriot-Watt University, Edinburgh, United Kingdom
| | - Ani Ayvazian-Hancock
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
- Centre of Biophotonics, University of St. Andrews, St. Andrews, United Kingdom
| | - Katherine Doucet
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
- Centre of Biophotonics, University of St. Andrews, St. Andrews, United Kingdom
| | - Owen Kantelberg
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, United Kingdom
| | - Lesley Motherwell
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
- Centre of Biophotonics, University of St. Andrews, St. Andrews, United Kingdom
| | - Fei Zhu
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Seth G. N. Grant
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Mathew H. Horrocks
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, United Kingdom
- IRR Chemistry Hub, Institute for Regeneration and Repair, University of Edinburgh, Edinburgh, United Kingdom
| | - Gareth B. Miles
- School of Psychology and Neuroscience, University of St. Andrews, St. Andrews, United Kingdom
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Bai X, Zhang K, Ou C, Nie B, Zhang J, Huang Y, Zhang Y, Huang J, Ouyang H, Cao M, Huang W. Selective activation of AKAP150/TRPV1 in ventrolateral periaqueductal gray GABAergic neurons facilitates conditioned place aversion in male mice. Commun Biol 2023; 6:742. [PMID: 37460788 PMCID: PMC10352381 DOI: 10.1038/s42003-023-05106-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 07/06/2023] [Indexed: 07/20/2023] Open
Abstract
Aversion refers to feelings of strong dislike or avoidance toward particular stimuli or situations. Aversion can be caused by pain stimuli and has a long-term negative impact on physical and mental health. Aversion can also be caused by drug abuse withdrawal, resulting in people with substance use disorder to relapse. However, the mechanisms underlying aversion remain unclear. The ventrolateral periaqueductal gray (vlPAG) is considered to play a key role in aversive behavior. Our study showed that inhibition of vlPAG GABAergic neurons significantly attenuated the conditioned place aversion (CPA) induced by hindpaw pain pinch or naloxone-precipitated morphine withdrawal. However, activating or inhibiting glutamatergic neurons, or activating GABAergic neurons cannot affect or alter CPA response. AKAP150 protein expression and phosphorylated TRPV1 (p-TRPV1) were significantly upregulated in these two CPA models. In AKAP150flox/flox mice and C57/B6J wild-type mice, cell-type-selective inhibition of AKAP150 in GABAergic neurons in the vlPAG attenuated aversion. However, downregulating AKAP150 in glutamatergic neurons did not attenuate aversion. Knockdown of AKAP150 in GABAergic neurons effectively reversed the p-TRPV1 upregulation in these two CPA models utilized in our study. Collectively, inhibition of the AKAP150/p-TRPV1 pathway in GABAergic neurons in the vlPAG may be considered a potential therapeutic target for the CPA response.
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Affiliation(s)
- Xiaohui Bai
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
- Department of Anesthesiology, Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation. Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Kun Zhang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Chaopeng Ou
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Bilin Nie
- Department of Anesthesiology, Guangdong Women and Children Hospital, Guangzhou, China
| | - Jianxing Zhang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Yongtian Huang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Yingjun Zhang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Jingxiu Huang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Handong Ouyang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
| | - Minghui Cao
- Department of Anesthesiology, Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation. Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Wan Huang
- Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
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Misery L, Pierre O, Le Gall-Ianotto C, Lebonvallet N, Chernyshov PV, Le Garrec R, Talagas M. Basic mechanisms of itch. J Allergy Clin Immunol 2023; 152:11-23. [PMID: 37201903 DOI: 10.1016/j.jaci.2023.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 05/20/2023]
Abstract
Pruritus (or itch) is an unpleasant sensation leading to a desire to scratch. In the epidermis, there are selective C or Aδ epidermal nerve endings that are pruriceptors. At their other ends, peripheral neurons form synapses with spinal neurons and interneurons. Many areas in the central nervous system are involved in itch processing. Although itch does not occur solely because of parasitic, allergic, or immunologic diseases, it is usually the consequence of neuroimmune interactions. Histamine is involved in a minority of itchy conditions, and many other mediators play a role: cytokines (eg, IL-4, IL-13, IL-31, IL-33, and thymic stromal lymphopoietin), neurotransmitters (eg, substance P, calcitonin gene-related peptide, vasoactive intestinal peptide, neuropeptide Y, NBNP, endothelin 1, and gastrin-releasing peptide), and neurotrophins (eg, nerve growth factor and brain-derived neurotrophic factor). Moreover, ion channels such as voltage-gated sodium channels, transient receptor potential vanilloid 1, transient receptor ankyrin, and transient receptor potential cation channel subfamily M (melastatin) member 8 play a crucial role. The main markers of nonhistaminergic pruriceptors are PAR-2 and MrgprX2. A notable phenomenon is the sensitization to pruritus, in which regardless of the initial cause of pruritus, there is an increased responsiveness of peripheral and central pruriceptive neurons to their normal or subthreshold afferent input in the context of chronic itch.
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Affiliation(s)
- Laurent Misery
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France.
| | - Ophélie Pierre
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Christelle Le Gall-Ianotto
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France
| | - Nicolas Lebonvallet
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Pavel V Chernyshov
- Department of Dermatology and Venereology, National Medical University, Kiev, Ukraine
| | - Raphaële Le Garrec
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France
| | - Matthieu Talagas
- Laboratoire Interactions Neurones-Keratinocytes (LINK), University of Brest, Brest, France; Department of Dermatology and Venereology, University Hospital of Brest, Brest, France
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Espinosa-Juárez JV, Chiquete E, Estañol B, Aceves JDJ. Optogenetic and Chemogenic Control of Pain Signaling: Molecular Markers. Int J Mol Sci 2023; 24:10220. [PMID: 37373365 DOI: 10.3390/ijms241210220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 06/05/2023] [Accepted: 06/10/2023] [Indexed: 06/29/2023] Open
Abstract
Pain is a complex experience that involves physical, emotional, and cognitive aspects. This review focuses specifically on the physiological processes underlying pain perception, with a particular emphasis on the various types of sensory neurons involved in transmitting pain signals to the central nervous system. Recent advances in techniques like optogenetics and chemogenetics have allowed researchers to selectively activate or inactivate specific neuronal circuits, offering a promising avenue for developing more effective pain management strategies. The article delves into the molecular targets of different types of sensory fibers such as channels, for example, TRPV1 in C-peptidergic fiber, TRPA1 in C-non-peptidergic receptors expressed differentially as MOR and DOR, and transcription factors, and their colocalization with the vesicular transporter of glutamate, which enable researchers to identify specific subtypes of neurons within the pain pathway and allows for selective transfection and expression of opsins to modulate their activity.
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Affiliation(s)
- Josue Vidal Espinosa-Juárez
- Escuela de Ciencias Químicas Sede Ocozocoautla, Universidad Autónoma de Chiapas, Ocozocoautla de Espinosa 29140, Mexico
| | - Erwin Chiquete
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
| | - Bruno Estañol
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
| | - José de Jesús Aceves
- Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City 14080, Mexico
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10
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Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy. Proc Natl Acad Sci U S A 2023; 120:e2216230120. [PMID: 36724251 PMCID: PMC9963752 DOI: 10.1073/pnas.2216230120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe6, β-Ala11, Phe13, Nle14] Bn (6-14), in complex with Gq heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and Gq proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.
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11
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Chen QY, Zhuo M. Glutamate acts as a key neurotransmitter for itch in the mammalian spinal cord. Mol Pain 2023; 19:17448069231152101. [PMID: 36604775 PMCID: PMC9846298 DOI: 10.1177/17448069231152101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Itch sensation is one of the major sensory experiences of humans and animals. Recent studies using genetic deletion techniques have proposed that gastrin-releasing peptide (GRP) is a key neurotransmitter for itch in the spinal cord. However, these studies are mainly based on behavioral responses and lack direct electrophysiological evidence that GRP indeed mediates itch information between primary afferent fibers and spinal dorsal horn neurons. In this review, we reviewed recent studies using different experimental approaches and proposed that glutamate but not GRP acts as the key neurotransmitter in the primary afferents in the transmission of itch. GRP is more likely to serve as an itch-related neuromodulator. In the cerebral cortex, we propose that the anterior cingulate cortex (ACC) plays a significant role in both itch and pain sensations. Only behavioral measurement of itch (scratching) is not sufficient for itch measurement, since scratching the itching area also produces pleasure. Integrative experimental approaches as well as better behavioral scoring models are needed to help to understand the neuronal mechanism of itch and aid future treatment for patients with pruritic diseases.
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Affiliation(s)
- Qi-Yu Chen
- Qingdao International Academician
Park, International Institute for Brain
Research, Qingdao, China,CAS Key Laboratory of Brain
Connectome and Manipulation, Interdisciplinary Center for Brain Information, The
Brain Cognition and Brain Disease Institute, Shenzhen-Hong Kong Institute of
Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen Institute of
Advanced Technology, Chinese Academy of Sciences Shenzhen
Institute of Advanced Technology, Shenzhen, China
| | - Min Zhuo
- Qingdao International Academician
Park, International Institute for Brain
Research, Qingdao, China,Department of Physiology, Faculty
of Medicine, University of Toronto, Toronto, ON, Canada,Min Zhuo, Institute of Brain Research,
Qingdao International Academician Park, Qingdao 266199, China.
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12
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Kanehisa K, Koga K, Maejima S, Shiraishi Y, Asai K, Shiratori-Hayashi M, Xiao MF, Sakamoto H, Worley PF, Tsuda M. Neuronal pentraxin 2 is required for facilitating excitatory synaptic inputs onto spinal neurons involved in pruriceptive transmission in a model of chronic itch. Nat Commun 2022; 13:2367. [PMID: 35501343 PMCID: PMC9061767 DOI: 10.1038/s41467-022-30089-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 04/14/2022] [Indexed: 11/08/2022] Open
Abstract
An excitatory neuron subset in the spinal dorsal horn (SDH) that expresses gastrin-releasing peptide receptors (GRPR) is critical for pruriceptive transmission. Here, we show that glutamatergic excitatory inputs onto GRPR+ neurons are facilitated in mouse models of chronic itch. In these models, neuronal pentraxin 2 (NPTX2), an activity-dependent immediate early gene product, is upregulated in the dorsal root ganglion (DRG) neurons. Electron microscopy reveals that NPTX2 is present at presynaptic terminals connected onto postsynaptic GRPR+ neurons. NPTX2-knockout prevents the facilitation of synaptic inputs to GRPR+ neurons, and repetitive scratching behavior. DRG-specific NPTX2 expression rescues the impaired behavioral phenotype in NPTX2-knockout mice. Moreover, ectopic expression of a dominant-negative form of NPTX2 in DRG neurons reduces chronic itch-like behavior in mice. Our findings indicate that the upregulation of NPTX2 expression in DRG neurons contributes to the facilitation of glutamatergic inputs onto GRPR+ neurons under chronic itch-like conditions, providing a potential therapeutic target.
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Affiliation(s)
- Kensho Kanehisa
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Keisuke Koga
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Hyogo, 663-8501, Japan
| | - Sho Maejima
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, 701-4303, Japan
| | - Yuto Shiraishi
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Konatsu Asai
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Miho Shiratori-Hayashi
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Mei-Fang Xiao
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, United States
| | - Hirotaka Sakamoto
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, 701-4303, Japan
| | - Paul F Worley
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, United States
| | - Makoto Tsuda
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
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13
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Hu L, Jiang GY, Wang YP, Hu ZB, Zhou BY, Zhang L, Song NN, Huang Y, Chai GD, Chen JY, Lang B, Xu L, Liu JL, Li Y, Wang QX, Ding YQ. The role of PTEN in primary sensory neurons in processing itch and thermal information in mice. Cell Rep 2022; 39:110724. [PMID: 35443189 DOI: 10.1016/j.celrep.2022.110724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 03/03/2022] [Accepted: 03/30/2022] [Indexed: 12/01/2022] Open
Abstract
PTEN is known as a tumor suppressor and plays essential roles in brain development. Here, we report that PTEN in primary sensory neurons is involved in processing itch and thermal information in adult mice. Deletion of PTEN in the dorsal root ganglia (DRG) is achieved in adult Drg11-CreER: PTENflox/flox (PTEN CKO) mice with oral administration of tamoxifen, and CKO mice develop pathological itch and elevated itch responses on exposure to various pruritogens. PTEN deletion leads to ectopic expression of TRPV1 and MrgprA3 in IB4+ non-peptidergic DRG neurons, and the TRPV1 is responsive to capsaicin. Importantly, the elevated itch responses are no longer present in Drg11-CreER: PTENflox/flox: TRPV1flox/flox (PTEN: TRPV1 dCKO) mice. In addition, thermal stimulation is enhanced in PTEN CKO mice but blunted in dCKO mice. PTEN-involved regulation of itch-related gene expression in DRG neurons provides insights for understanding molecular mechanism of itch and thermal sensation at the spinal level.
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Affiliation(s)
- Ling Hu
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Guan-Yu Jiang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ying-Ping Wang
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Zhi-Bin Hu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Bing-Yao Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Lei Zhang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ning-Ning Song
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Ying Huang
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China
| | - Guo-Dong Chai
- Department of Anesthesiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Jia-Yin Chen
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Bing Lang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Lin Xu
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Jun-Ling Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Yong Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Qing-Xiu Wang
- Department of Anesthesiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
| | - Yu-Qiang Ding
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China.
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14
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Glutamate in primary afferents is required for itch transmission. Neuron 2022; 110:809-823.e5. [PMID: 34986325 PMCID: PMC8898340 DOI: 10.1016/j.neuron.2021.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [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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15
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Larsson M, Nagi SS. Role of C-tactile fibers in pain modulation: animal and human perspectives. Curr Opin Behav Sci 2022. [DOI: 10.1016/j.cobeha.2021.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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16
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Laliberte AM, Farah C, Steiner KR, Tariq O, Bui TV. Changes in Sensorimotor Connectivity to dI3 Interneurons in Relation to the Postnatal Maturation of Grasping. Front Neural Circuits 2022; 15:768235. [PMID: 35153680 PMCID: PMC8828486 DOI: 10.3389/fncir.2021.768235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/31/2021] [Indexed: 11/23/2022] Open
Abstract
Primitive reflexes are evident shortly after birth. Many of these reflexes disappear during postnatal development as part of the maturation of motor control. This study investigates the changes of connectivity related to sensory integration by spinal dI3 interneurons during the time in which the palmar grasp reflex gradually disappears in postnatal mice pups. Our results reveal an increase in GAD65/67-labeled terminals to perisomatic Vglut1-labeled sensory inputs contacting cervical and lumbar dI3 interneurons between postnatal day 3 and day 25. In contrast, there were no changes in the number of perisomatic Vglut1-labeled sensory inputs to lumbar and cervical dI3 interneurons other than a decrease between postnatal day 15 and day 25. Changes in postsynaptic GAD65/67-labeled inputs to dI3 interneurons were inconsistent with a role in the sustained loss of the grasp reflex. These results suggest a possible link between the maturation of hand grasp during postnatal development and increased presynaptic inhibition of sensory inputs to dI3 interneurons.
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Affiliation(s)
- Alex M. Laliberte
- Brain and Mind Research Institute, Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Carl Farah
- Brain and Mind Research Institute, Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Kyra R. Steiner
- Brain and Mind Research Institute, Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Omar Tariq
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Tuan V. Bui
- Brain and Mind Research Institute, Department of Biology, University of Ottawa, Ottawa, ON, Canada
- *Correspondence: Tuan V. Bui
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17
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Serra GP, Guillaumin A, Dumas S, Vlcek B, Wallén-Mackenzie Å. Midbrain Dopamine Neurons Defined by TrpV1 Modulate Psychomotor Behavior. Front Neural Circuits 2021; 15:726893. [PMID: 34858142 PMCID: PMC8632262 DOI: 10.3389/fncir.2021.726893] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Dopamine (DA) neurons of the ventral tegmental area (VTA) continue to gain attention as far more heterogeneous than previously realized. Within the medial aspect of the VTA, the unexpected presence of TrpV1 mRNA has been identified. TrpV1 encodes the Transient Receptor Potential cation channel subfamily V member 1, TRPV1, also known as the capsaicin receptor, well recognized for its role in heat and pain processing by peripheral neurons. In contrast, the brain distribution of TrpV1 has been debated. Here, we hypothesized that the TrpV1+ identity defines a distinct subpopulation of VTA DA neurons. To explore these brain TrpV1+ neurons, histological analyses and Cre-driven mouse genetics were employed. TrpV1 mRNA was most strongly detected at the perinatal stage forming a band of scattered neurons throughout the medial VTA, reaching into the posterior hypothalamus. Within the VTA, the majority of TrpV1 co-localized with both Tyrosine hydroxylase (Th) and Vesicular monoamine transporter 2 (Vmat2), confirming a DA phenotype. However, TrpV1 also co-localized substantially with Vesicular glutamate transporter 2 (Vglut2), representing the capacity for glutamate (GLU) release. These TrpV1+/Th+/Vglut2+/Vmat2+ neurons thus constitute a molecularly and anatomically distinct subpopulation of DA-GLU co-releasing neurons. To assess behavioral impact, a TrpV1Cre -driven strategy targeting the Vmat2 gene in mice was implemented. This manipulation was sufficient to alter psychomotor behavior induced by amphetamine. The acute effect of the drug was accentuated above control levels, suggesting super-sensitivity in the drug-na ve state resembling a "pre-sensitized" phenotype. However, no progressive increase with repeated injections was observed. This study identifies a distinct TrpV1+ VTA subpopulation as a critical modulatory component in responsiveness to amphetamine. Moreover, expression of the gene encoding TRPV1 in selected VTA neurons opens up for new possibilities in pharmacological intervention of this heterogeneous, but clinically important, brain area.
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Affiliation(s)
- Gian Pietro Serra
- Unit of Comparative Physiology, Department of Organism Biology, Uppsala University, Uppsala, Sweden
| | - Adriane Guillaumin
- Unit of Comparative Physiology, Department of Organism Biology, Uppsala University, Uppsala, Sweden
| | | | - Bianca Vlcek
- Unit of Comparative Physiology, Department of Organism Biology, Uppsala University, Uppsala, Sweden
| | - Åsa Wallén-Mackenzie
- Unit of Comparative Physiology, Department of Organism Biology, Uppsala University, Uppsala, Sweden
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18
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The link between neurology and behavior in veterinary medicine: A review. J Vet Behav 2021. [DOI: 10.1016/j.jveb.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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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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20
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TRPC3 Antagonizes Pruritus in a Mouse Contact Dermatitis Model. J Invest Dermatol 2021; 142:1136-1144. [PMID: 34570999 DOI: 10.1016/j.jid.2021.08.433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/27/2021] [Accepted: 08/16/2021] [Indexed: 11/22/2022]
Abstract
Contact dermatitis (CD), including allergic and irritant CD, are common dermatological diseases and are characterized by an erythematous rash and severe itch. In this study, we investigated the function of TRPC3, a canonical transient receptor potential channel highly expressed in type 1 nonpeptidergic (NP1) nociceptive primary afferents and other cell types, in a mouse CD model. Although TrpC3 null mice had little deficits in acute somatosensation, they showed significantly increased scratching with CD. In addition, TrpC3 null mice displayed no differences in mechanical and thermal hypersensitivity in an inflammatory pain model, suggesting that this channel preferentially functions to antagonize CD-induced itch. Using dorsal root ganglia and panimmune-specific TrpC3 conditional knockout mice, we determined that TrpC3 in dorsal root ganglia neurons but not in immune cells is required for this phenotype. Furthermore, the number of MRGPRD+ NP1 afferents in CD-affected dorsal root ganglia is significantly reduced in TrpC3-mutant mice. Taken together, our results suggest that TrpC3 plays a critical role in NP1 afferents to cope with CD-induced excitotoxicity and that the degeneration of NP1 fibers may lead to an increased itch of CD. Our study identified a role of TrpC3 and NP1 afferents in CD pathology.
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21
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Misery L, Brenaut E, Pierre O, Le Garrec R, Gouin O, Lebonvallet N, Abasq-Thomas C, Talagas M, Le Gall-Ianotto C, Besner-Morin C, Fluhr JW, Leven C. Chronic itch: emerging treatments following new research concepts. Br J Pharmacol 2021; 178:4775-4791. [PMID: 34463358 DOI: 10.1111/bph.15672] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 11/29/2022] Open
Abstract
Until recently, itch pathophysiology was poorly understood and treatments were poorly effective in relieving itch. Current progress in our knowledge of the itch processing, the numerous mediators and receptors involved has led to a large variety of possible therapeutic pathways. Currently, inhibitors of IL-31, IL-4/13, NK1 receptors, opioids and cannabinoids, JAK, PDE4 or TRP are the main compounds involved in clinical trials. However, many new targets, such as Mas-related GPCRs and unexpected new pathways need to be also explored.
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Affiliation(s)
- Laurent Misery
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | - Emilie Brenaut
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | | | | | - Olivier Gouin
- LIEN, Univ Brest, Brest, France.,INSERM UMR 1163, Laboratory of Genetic Skin Diseases, Imagine Institute, Paris, France.,University of Paris, Paris, France
| | | | - Claire Abasq-Thomas
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | - Matthieu Talagas
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France
| | | | - Catherine Besner-Morin
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France.,Division of Dermatology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Joachim W Fluhr
- LIEN, Univ Brest, Brest, France.,Department of Dermatology, University Hospital of Brest, Brest, France.,Department of Dermatology, Charité Universitätsmedizin, Berlin, Germany
| | - Cyril Leven
- LIEN, Univ Brest, Brest, France.,EA3878, FCRIN INNOVTE, groupe d'étude thrombose Bretagne Occidentale, Brest, France.,Department of Biochemistry and Pharmaco-Toxicology, University Hospital of Brest, Brest, France
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22
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Common and discrete mechanisms underlying chronic pain and itch: peripheral and central sensitization. Pflugers Arch 2021; 473:1603-1615. [PMID: 34245379 DOI: 10.1007/s00424-021-02599-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 05/26/2021] [Accepted: 06/22/2021] [Indexed: 12/30/2022]
Abstract
Normally, an obvious antagonism exists between pain and itch. In normal conditions, painful stimuli suppress itch sensation, whereas pain killers often generate itch. Although pain and itch are mediated by separate pathways under normal conditions, most chemicals are not highly specific to one sensation in chronic pathologic conditions. Notably, in patients with neuropathic pain, histamine primarily induces pain rather than itch, while in patients with atopic dermatitis, bradykinin triggers itch rather than pain. Accordingly, repetitive scratching even enhances itch sensation in chronic itch conditions. Physicians often prescribe pain relievers to patients with chronic itch, suggesting common mechanisms underlying chronic pain and itch, especially peripheral and central sensitization. Rather than separating itch and pain, studies should investigate chronic itch and pain including neuropathic and inflammatory conditions. Here, we reviewed chronic sensitization leading to chronic pain and itch at both peripheral and central levels. Studies investigating the connection between pain and itch facilitate the development of new therapeutics against both chronic dysesthesias based on the underlying pathophysiology.
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23
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Mishra SK, Wheeler JJ, Pitake S, Ding H, Jiang C, Fukuyama T, Paps JS, Ralph P, Coyne J, Parkington M, DeBrecht J, Ehrhardt-Humbert LC, Cruse GP, Bäumer W, Ji RR, Ko MC, Olivry T. Periostin Activation of Integrin Receptors on Sensory Neurons Induces Allergic Itch. Cell Rep 2021; 31:107472. [PMID: 32268102 PMCID: PMC9210348 DOI: 10.1016/j.celrep.2020.03.036] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 02/04/2020] [Accepted: 03/11/2020] [Indexed: 12/15/2022] Open
Abstract
Chronic allergic itch is a common symptom affecting millions of people and animals, but its pathogenesis is not fully explained. Herein, we show that periostin, abundantly expressed in the skin of patients with atopic dermatitis (AD), induces itch in mice, dogs, and monkeys. We identify the integrin αVβ3 expressed on a subset of sensory neurons as the periostin receptor. Using pharmacological and genetic approaches, we inhibited the function of neuronal integrin αVβ3, which significantly reduces periostin-induced itch in mice. Furthermore, we show that the cytokine TSLP, the application of AD-causing MC903 (calcipotriol), and house dust mites all induce periostin secretion. Finally, we establish that the JAK/STAT pathway is a key regulator of periostin secretion in keratinocytes. Altogether, our results identify a TSLP-periostin reciprocal activation loop that links the skin to the spinal cord via peripheral sensory neurons, and we characterize the non-canonical functional role of an integrin in itch. Mishra et al. demonstrate periostin-induced itch in mice, dogs, and monkeys and identify the integrin αVβ3 as the periostin neuronal receptor. They find that keratinocytes release periostin in response to TSLP, thus identifying a possible reciprocal vicious circle implicating the cytokine TSLP and periostin in chronic allergic itch.
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Affiliation(s)
- Santosh K Mishra
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA; The WM Keck Behavioral Center, North Carolina State University, Raleigh, NC, USA; Program in Genetics, North Carolina State University, Raleigh, NC, USA.
| | - Joshua J Wheeler
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
| | - Saumitra Pitake
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Huiping Ding
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | - Tomoki Fukuyama
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Judy S Paps
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Patrick Ralph
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Jacob Coyne
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Michelle Parkington
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Jennifer DeBrecht
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Lauren C Ehrhardt-Humbert
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Glenn P Cruse
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
| | - Wolfgang Bäumer
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | | | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Thierry Olivry
- Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA; Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
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24
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Langedijk JAGM, Beuers UH, Oude Elferink RPJ. Cholestasis-Associated Pruritus and Its Pruritogens. Front Med (Lausanne) 2021; 8:639674. [PMID: 33791327 PMCID: PMC8006388 DOI: 10.3389/fmed.2021.639674] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/12/2021] [Indexed: 12/17/2022] Open
Abstract
Pruritus is a debilitating symptom of various cholestatic disorders, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and inherited progressive familial intrahepatic cholestasis (PFIC). The molecular mechanisms leading to cholestasis-associated pruritus are still unresolved and the involved pruritogens are indecisive. As a consequence of pruritus, patients suffer from sleep deprivation, loss of daytime concentration, auto-mutilation and sometimes even suicidal ideations. Current guideline-approved therapy of cholestasis-associated pruritus includes stepwise administration of several medications, which may alleviate complaints in some, but not all affected patients. Therefore, also experimental therapeutic approaches are required to improve patients' quality of life. This article reviews the current state of research on pruritogens and their receptors, and shortly discusses the most recent experimental therapies.
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Affiliation(s)
- Jacqueline A G M Langedijk
- Amsterdam University Medical Centers, Tytgat Institute for Liver and Intestinal Research, Research Institute Amsterdam Gastroenterology, Endocrinology and Metabolism (AGEM), University of Amsterdam, Amsterdam, Netherlands
| | - Ulrich H Beuers
- Amsterdam University Medical Centers, Tytgat Institute for Liver and Intestinal Research, Research Institute Amsterdam Gastroenterology, Endocrinology and Metabolism (AGEM), University of Amsterdam, Amsterdam, Netherlands
| | - Ronald P J Oude Elferink
- Amsterdam University Medical Centers, Tytgat Institute for Liver and Intestinal Research, Research Institute Amsterdam Gastroenterology, Endocrinology and Metabolism (AGEM), University of Amsterdam, Amsterdam, Netherlands
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25
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Li HP, Wang XY, Chen C, Li JJ, Yu C, Lin LX, Yu ZE, Jin ZY, Zhu H, Xiang HC, Hu XF, Cao J, Jing XH, Li M. 100 Hz Electroacupuncture Alleviated Chronic Itch and GRPR Expression Through Activation of Kappa Opioid Receptors in Spinal Dorsal Horn. Front Neurosci 2021; 15:625471. [PMID: 33664646 PMCID: PMC7921323 DOI: 10.3389/fnins.2021.625471] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/20/2021] [Indexed: 11/19/2022] Open
Abstract
Background Clinical studies have shown that electroacupuncture (EA) alleviates chronic itch. Gastrin-releasing peptide receptor (GRPR) and dynorphin (DYN) in the spinal dorsal horn positively or negatively regulate itch, respectively. However, which frequency of EA is effective on relieving chronic itch and reducing the expression of GRPR, whether DYN-A in the spinal cord is involved in the underlying mechanism of the antipruritus effect of EA remains unknown. Methods The mixture of acetone and diethyl ether (1:1) [designated as AEW (acetone/diethyl ether and water) treatment] was used to induce the dry skin model of chronic itch. EA was applied to Quchi (LI11) and Hegu (LI4). Western blot was used to detect the expression of GRPR and DYN-A. Immunofluorescence was used to detect the expression of DYN-A. Results The AEW administration induced remarkable spontaneous scratching, enhanced the expression of GRPR, and reduced the expression of DYN-A. Compared with the sham EA, 2 Hz EA, or 15 Hz EA group, 100 Hz EA was the most effective frequency for relieving chronic itch, reducing the expression of GRPR, and increasing the expression of DYN-A in the cervical dorsal horn. Furthermore, intraperitoneal injection of kappa opioid receptors (KORs) antagonist nor-Binaltorphimine dihydrochloride (nor-BNI) significantly reversed the effect of 100 Hz EA on the inhibition of both itching behavior and GRPR expression. Conclusion EA at 100 Hz is the most effective frequency that inhibits chronic itch and GRPR expression through activation of KORs in the spinal dorsal horn, which can effectively guide the clinical treatment and improve the antipruritic effect of acupuncture.
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Affiliation(s)
- Hong-Ping Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Yu Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Chao Chen
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing-Jing Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chi Yu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Xue Lin
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zi-E Yu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi-Yuan Jin
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - He Zhu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Chun Xiang
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xue-Fei Hu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Cao
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiang-Hong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Man Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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26
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Kelemen B, Pinto S, Kim N, Lisztes E, Hanyicska M, Vládar A, Oláh A, Pénzes Z, Shu B, Vriens J, Bíró T, Rohács T, Voets T, Tóth BI. The TRPM3 ion channel mediates nociception but not itch evoked by endogenous pruritogenic mediators. Biochem Pharmacol 2021; 183:114310. [PMID: 33130130 PMCID: PMC8086171 DOI: 10.1016/j.bcp.2020.114310] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/22/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023]
Abstract
During the molecular transduction of itch, the stimulation of pruriceptors on sensory fibers leads to the activation or sensitization of ion channels, which results in a consequent depolarization of the neurons. These ion channels mostly belong to the transient receptor potential (TRP) channels, which are involved in nociception and thermosensation. In particular, TRPV1 and TRPA1 were described in the transduction of both thermal nociception as well as histaminergic and non-histaminergic itch. The thermosensitive TRPM3 plays an indispensable role in heat nociception together with TRPV1 and TRPA1. However, the role of TRPM3 in the development of pruritus has not been studied yet. Therefore, in this study we aimed at investigating the potential role of TRPM3 in the transduction of pruritus and pain by investigating itch- and nociception-related behavior of Trpm3+/+ and Trpm3-/- mice, and by studying the activation of somatosensory neurons isolated from trigeminal ganglia upon application of algogenic and pruritogenic substances. Activators of TRPM3 evoked only nocifensive responses, but not itch in Trpm3+/+ animals, and these nocifensive responses were abolished in the Trpm3-/- strain. Histamine and endogenous non-histaminergic pruritogens induced itch in both Trpm3+/+ and Trpm3-/- mice to a similar extent. Genetic deletion or pharmacological blockade diminished TRPM3 mediated Ca2+ responses of sensory neurons, but did not affect responses evoked by pruritogenic substances. Our results demonstrate that, in contrast to other thermosensitive TRP channels, TRPM3 selectively mediates nociception, but not itch sensation, and suggest that TRPM3 is a promising candidate to selectively target pain sensation.
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Affiliation(s)
- Balázs Kelemen
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Laboratory of Ion Channel Research (VIB-KU Leuven Center for Brain & Disease Research) Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Silvia Pinto
- Laboratory of Ion Channel Research (VIB-KU Leuven Center for Brain & Disease Research) Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Nawoo Kim
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Erika Lisztes
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Martin Hanyicska
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Anita Vládar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Oláh
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zsófia Pénzes
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary
| | - Brian Shu
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Joris Vriens
- Laboratory of Endometrium, Endometriosis and Reproductive Medicine, Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Tamás Bíró
- Department of Immunology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tibor Rohács
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Thomas Voets
- Laboratory of Ion Channel Research (VIB-KU Leuven Center for Brain & Disease Research) Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Balázs István Tóth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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27
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Itch: A Paradigm of Neuroimmune Crosstalk. Immunity 2020; 52:753-766. [PMID: 32433948 DOI: 10.1016/j.immuni.2020.04.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/07/2020] [Accepted: 04/17/2020] [Indexed: 02/07/2023]
Abstract
Although the medical definition of itch has been in existence for 360 years, only in the last 20 years have we begun to understand the basic mechanisms that underlie this unique sensation. Therapeutics that specifically target chronic itch as a pathologic entity are currently still not available. Recent seminal advances in itch circuitry within the nervous system have intersected with discoveries in immunology in unexpected ways to rapidly inform emerging treatment strategies. The current review aims to introduce these basic concepts in itch biology and highlight how distinct immunologic pathways integrate with recently identified itch-sensory circuits in the nervous system to inform a major new paradigm of neuroimmunology and therapeutic development for chronic itch.
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28
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Meixiong J, Dong X, Weng HJ. Neuropathic Itch. Cells 2020; 9:cells9102263. [PMID: 33050211 PMCID: PMC7601786 DOI: 10.3390/cells9102263] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 12/12/2022] Open
Abstract
Neurologic insults as varied as inflammation, stroke, and fibromyalgia elicit neuropathic pain and itch. Noxious sensation results when aberrantly increased afferent signaling reaches percept-forming cortical neurons and can occur due to increased sensory signaling, decreased inhibitory signaling, or a combination of both processes. To treat these symptoms, detailed knowledge of sensory transmission, from innervated end organ to cortex, is required. Molecular, genetic, and behavioral dissection of itch in animals and patients has improved understanding of the receptors, cells, and circuits involved. In this review, we will discuss neuropathic itch with a focus on the itch-specific circuit.
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Affiliation(s)
- James Meixiong
- Solomon H. Snyder Department of Neuroscience and Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
| | - Xinzhong Dong
- Solomon H. Snyder Department of Neuroscience, Department of Dermatology, and Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hao-Jui Weng
- Department of Dermatology, Taipei Medical University-Shuang Ho Hospital, New Taipei City 23561, Taiwan
- Department of Dermatology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
- Correspondence:
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29
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Islam MN, Maeda N, Miyasato E, Jahan MR, Tarif AMM, Ishino T, Nozaki K, Masumoto KH, Yanai A, Shinoda K. Expression of huntingtin-associated protein 1 in adult mouse dorsal root ganglia and its neurochemical characterization in reference to sensory neuron subpopulations. IBRO Rep 2020; 9:258-269. [PMID: 33089002 PMCID: PMC7560692 DOI: 10.1016/j.ibror.2020.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 10/02/2020] [Indexed: 12/13/2022] Open
Abstract
This study is the first to examine HAP1-expression in dorsal root ganglia (DRG). HAP1 is highly co-expressed with the markers of nociceptive/proprioceptive neurons. HAP1 is completely lacking in the touch-sensitive DRG neurons. HAP1 may play an important role in modulating nociceptive/proprioceptive functions. It will be of great interest to clarify the pathophysiological role of HAP1 in DRG.
Huntingtin-associated protein 1 (HAP1) is a polyglutamine (polyQ) length-dependent interactor with causal agents in several neurodegenerative diseases and has been regarded as a protective factor against neurodegeneration. In normal rodent brain and spinal cord, HAP1 is abundantly expressed in the areas that are spared from neurodegeneration while those areas with little HAP1 are frequent targets of neurodegeneration. We have recently showed that HAP1 is highly expressed in the spinal dorsal horn and may participate in modification/protection of certain sensory functions. Neurons in the dorsal root ganglia (DRG) transmits sensory stimuli from periphery to spinal cord/brain stem. Nevertheless, to date HAP1 expression in DRG remains unreported. In this study, the expression of HAP1 in cervical, thoracic, lumbar and sacral DRG in adult male mice and its relationships with different chemical markers for sensory neurons were examined using Western blot and immunohistochemistry. HAP1-immunoreactivity was detected in the cytoplasm of DRG neurons, and the percentage of HAP1-immunoreactive (ir) DRG neurons was ranged between 28–31 %. HAP1-immunoreactivity was comparatively more in the small cells (47–58 %) and medium cells (40–44 %) than that in the large cells (9–11 %). Double-immunostaining for HAP1 and markers for nociceptive or mechanoreceptive neurons showed that about 70–80 % of CGRP-, SP-, CB-, NOS-, TRPV1-, CR- and PV-ir neurons expressed HAP1. In contrast, HAP1 was completely lacking in TH-ir neurons. Our current study is the first to clarify that HAP1 is highly expressed in nociceptive/proprioceptive neurons but absent in light-touch-sensitive TH neurons, suggesting the potential importance of HAP1 in pain transduction and proprioception.
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Key Words
- CB, calbindin
- CGRP, calcitonin gene-related peptide
- CR, calretinin
- DAB, diaminobenzidine
- DRG, dorsal root ganglia
- HAP1, Huntingtin-associated protein 1
- Huntingtin-associated protein 1
- Iba1, ionized calcium-binding adapter molecule 1
- Immunohistochemistry
- LTMRs, low-threshold mechanoreceptors
- MRGPR, Mas-related G-protein-coupled receptor
- NDS, normal donkey serum
- NOS, nitric oxide synthetase
- NeuN, neuronal nuclei
- Neurodegeneration
- Neuroprotection
- PB, phosphate buffer
- PV, parvalbumin
- Peripheral nervous system
- SBMA, spinal and bulbar muscular atrophy
- SP, substance P
- STB, stigmoid body
- Sensory neurons
- TBST, Tris-buffered saline with 0.1 % Tween
- TH, tyrosine hydroxylase
- TRPV1, transient receptor potential vanilloid 1
- VGLUT, vesicular glutamate transporter
- htt, huntingtin
- polyQ, polyglutamine
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Affiliation(s)
- Md Nabiul Islam
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Naoki Maeda
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Emi Miyasato
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Mir Rubayet Jahan
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan.,Department of Anatomy and Histology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh
| | - Abu Md Mamun Tarif
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Taiga Ishino
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Kanako Nozaki
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Koh-Hei Masumoto
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Akie Yanai
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan.,Department of Basic Laboratory Sciences, Faculty of Medicine and Health Sciences, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
| | - Koh Shinoda
- Division of Neuroanatomy, Department of Neuroscience, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, 755-8505, Japan
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30
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Abstract
Itch is a unique sensation that helps organisms scratch away external threats; scratching itself induces an immune response that can contribute to more itchiness. Itch is induced chemically in the peripheral nervous system via a wide array of receptors. Given the superficial localization of itch neuron terminals, cells that dwell close to the skin contribute significantly to itch. Certain mechanical stimuli mediated by recently discovered circuits also contribute to the itch sensation. Ultimately, in the spinal cord, and likely in the brain, circuits that mediate touch, pain, and itch engage in cross modulation. Much of itch perception is still a mystery, but we present in this review the known ligands and receptors associated with itch. We also describe experiments and findings from investigations into the spinal and supraspinal circuitry responsible for the sensation of itch.
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Affiliation(s)
- Mark Lay
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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31
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Nanostructural Diversity of Synapses in the Mammalian Spinal Cord. Sci Rep 2020; 10:8189. [PMID: 32424125 PMCID: PMC7235094 DOI: 10.1038/s41598-020-64874-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/21/2020] [Indexed: 11/25/2022] Open
Abstract
Functionally distinct synapses exhibit diverse and complex organisation at molecular and nanoscale levels. Synaptic diversity may be dependent on developmental stage, anatomical locus and the neural circuit within which synapses reside. Furthermore, astrocytes, which align with pre and post-synaptic structures to form ‘tripartite synapses’, can modulate neural circuits and impact on synaptic organisation. In this study, we aimed to determine which factors impact the diversity of excitatory synapses throughout the lumbar spinal cord. We used PSD95-eGFP mice, to visualise excitatory postsynaptic densities (PSDs) using high-resolution and super-resolution microscopy. We reveal a detailed and quantitative map of the features of excitatory synapses in the lumbar spinal cord, detailing synaptic diversity that is dependent on developmental stage, anatomical region and whether associated with VGLUT1 or VGLUT2 terminals. We report that PSDs are nanostructurally distinct between spinal laminae and across age groups. PSDs receiving VGLUT1 inputs also show enhanced nanostructural complexity compared with those receiving VGLUT2 inputs, suggesting pathway-specific diversity. Finally, we show that PSDs exhibit greater nanostructural complexity when part of tripartite synapses, and we provide evidence that astrocytic activation enhances PSD95 expression. Taken together, these results provide novel insights into the regulation and diversification of synapses across functionally distinct spinal regions and advance our general understanding of the ‘rules’ governing synaptic nanostructural organisation.
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32
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González-Cano R, Montilla-García Á, Ruiz-Cantero MC, Bravo-Caparrós I, Tejada MÁ, Nieto FR, Cobos EJ. The search for translational pain outcomes to refine analgesic development: Where did we come from and where are we going? Neurosci Biobehav Rev 2020; 113:238-261. [PMID: 32147529 DOI: 10.1016/j.neubiorev.2020.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/06/2020] [Accepted: 03/04/2020] [Indexed: 12/11/2022]
Abstract
Pain measures traditionally used in rodents record mere reflexes evoked by sensory stimuli; the results thus may not fully reflect the human pain phenotype. Alterations in physical and emotional functioning, pain-depressed behaviors and facial pain expressions were recently proposed as additional pain outcomes to provide a more accurate measure of clinical pain in rodents, and hence to potentially enhance analgesic drug development. We aimed to review how preclinical pain assessment has evolved since the development of the tail flick test in 1941, with a particular focus on a critical analysis of some nonstandard pain outcomes, and a consideration of how sex differences may affect the performance of these pain surrogates. We tracked original research articles in Medline for the following periods: 1973-1977, 1983-1987, 1993-1997, 2003-2007, and 2014-2018. We identified 606 research articles about alternative surrogate pain measures, 473 of which were published between 2014 and 2018. This indicates that preclinical pain assessment is moving toward the use of these measures, which may soon become standard procedures in preclinical pain laboratories.
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Affiliation(s)
- Rafael González-Cano
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain.
| | - Ángeles Montilla-García
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain.
| | - M Carmen Ruiz-Cantero
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain.
| | - Inmaculada Bravo-Caparrós
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain.
| | - Miguel Á Tejada
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain; IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria.
| | - Francisco R Nieto
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain.
| | - Enrique J Cobos
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Armilla, Granada, Spain; Instituto de Investigación Biosanitaria ibs.GRANADA, Granada, Spain; Teófilo Hernando Institute for Drug Discovery, Madrid, Spain.
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33
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Kiguchi N, Uta D, Ding H, Uchida H, Saika F, Matsuzaki S, Fukazawa Y, Abe M, Sakimura K, Ko MC, Kishioka S. GRP receptor and AMPA receptor cooperatively regulate itch-responsive neurons in the spinal dorsal horn. Neuropharmacology 2020; 170:108025. [PMID: 32142790 DOI: 10.1016/j.neuropharm.2020.108025] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/10/2020] [Accepted: 02/27/2020] [Indexed: 01/19/2023]
Abstract
Gastrin-releasing peptide (GRP) receptor-expressing (GRPR)+ neurons have a central role in the spinal transmission of itch. Because their fundamental regulatory mechanisms are not yet understood, it is important to determine how such neurons are excited and integrate itch sensation. In this study, we investigated the mechanisms for the activation of itch-responsive GRPR+ neurons in the spinal dorsal horn (SDH). GRPR+ neurons expressed the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) containing the GluR2 subunit. In mice, peripherally elicited histaminergic and non-histaminergic itch was prevented by intrathecal (i.t.) administration of the AMPAR antagonist NBQX, which was consistent with the fact that firing of GRPR+ neurons in SDH under histaminergic and non-histaminergic itch was completely blocked by NBQX, but not by the GRPR antagonist RC-3095. Because GRP+ neurons in SDH contain glutamate, we investigated the role of GRP+ (GRP+/Glu+) neurons in regulating itch. Chemogenetic inhibition of GRP+ neurons suppressed both histaminergic and non-histaminergic itch without affecting the mechanical pain threshold. In nonhuman primates, i.t. administration of NBQX also attenuated peripherally elicited itch without affecting the thermal pain threshold. In a mouse model of diphenylcyclopropenone (DCP)-induced contact dermatitis, GRP, GRPR, and AMPAR subunits were upregulated in SDH. DCP-induced itch was prevented by either silencing GRP+ neurons or ablation of GRPR+ neurons. Altogether, these findings demonstrate that GRP and glutamate cooperatively regulate GRPR+ AMPAR+ neurons in SDH, mediating itch sensation. GRP-GRPR and the glutamate-AMPAR system may play pivotal roles in the spinal transmission of itch in rodents and nonhuman primates.
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Affiliation(s)
- Norikazu Kiguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama City, Wakayama, 641-0012, Japan.
| | - Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama City, Toyama, 930-0194, Japan
| | - Huiping Ding
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, 27157, USA
| | - Hitoshi Uchida
- Department of Cellular Neuropathology, Brain Research Institute Niigata University, Niigata City, Niigata, 951-8585, Japan
| | - Fumihiro Saika
- Department of Pharmacology, Wakayama Medical University, Wakayama City, Wakayama, 641-0012, Japan
| | - Shinsuke Matsuzaki
- Department of Pharmacology, Wakayama Medical University, Wakayama City, Wakayama, 641-0012, Japan
| | - Yohji Fukazawa
- Department of Anatomy, Kansai University of Health Sciences, Sennan-gun, Osaka, 590-0482, Japan
| | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata City, Niigata, 951-8585, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata City, Niigata, 951-8585, Japan
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, 27157, USA; W.G. Hefner Veterans Affairs Medical Center, Salisbury, NC, 28144, USA
| | - Shiroh Kishioka
- Department of Pharmacology, Wakayama Medical University, Wakayama City, Wakayama, 641-0012, Japan
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VGLUT2/Cdk5/p25 Signaling Pathway Contributed to Inflammatory Pain by Complete Freund's Adjuvant. Pain Res Manag 2020; 2020:4807674. [PMID: 32190166 PMCID: PMC7066405 DOI: 10.1155/2020/4807674] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/09/2020] [Accepted: 01/16/2020] [Indexed: 01/28/2023]
Abstract
Vesicular glutamate transporter type 2 (VGLUT2) is known to play an important role in mediating heat hyperalgesia induced by inflammation. However, the underlying mechanism for this activity is poorly understood. Cyclin-dependent kinase 5 (Cdk5), serving as a key regulator in modulating release of glutamate, acted a key player in the formation of heat hyperalgesia of inflammatory pain. However, it remains unknown whether there is a bridge between Cdk5 and VGLUT2 for mediating inflammatory pain. Therefore, we designed the experiment to determine whether VGLUT2 signaling pathway is involved in inflammatory pain mediated by Cdk5 in the inflammatory pain model induced by complete Freund's adjuvant (CFA). Our results showed that the coexpression of Cdk5/VGLUT2 in small- and medium-sized neuronal cells of the dorsal root ganglion (DRG) and spinal cord between days 1 and 3 following subcutaneous injection of CFA was significantly increased. Moreover, our study revealed that the expression of VGLUT2 protein in the DRG and spinal cord was remarkably increased between days 1 and 3 following CFA injection and was significantly reduced by roscovitine, a selective antagonist of Cdk5. Additionally, p25 but not p35, an activator of Cdk5, protein was significantly increased by CFA and reduced by roscovitine. Our findings suggested that VGLUT2/Cdk5 signaling pathway contributes to inflammatory pain mediated by Cdk5/p25.
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35
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Pain Inhibits GRPR Neurons via GABAergic Signaling in the Spinal Cord. Sci Rep 2019; 9:15804. [PMID: 31676846 PMCID: PMC6825123 DOI: 10.1038/s41598-019-52316-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 10/11/2019] [Indexed: 11/30/2022] Open
Abstract
It has been known that algogens and cooling could inhibit itch sensation; however, the underlying molecular and neural mechanisms remain poorly understood. Here, we show that the spinal neurons expressing gastrin releasing peptide receptor (GRPR) primarily comprise excitatory interneurons that receive direct and indirect inputs from C and Aδ fibers and form contacts with projection neurons expressing the neurokinin 1 receptor (NK1R). Importantly, we show that noxious or cooling agents inhibit the activity of GRPR neurons via GABAergic signaling. By contrast, capsaicin, which evokes a mix of itch and pain sensations, enhances both excitatory and inhibitory spontaneous synaptic transmission onto GRPR neurons. These data strengthen the role of GRPR neurons as a key circuit for itch transmission and illustrate a spinal mechanism whereby pain inhibits itch by suppressing the function of GRPR neurons.
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Abstract
Recent studies have made significant progress in identifying distinct populations of peripheral neurons involved in itch transmission, whereas the cellular identity of spinal interneurons that contribute to itch processing is still a debate. Combining genetic and pharmacological ablation of spinal excitatory neuronal subtypes and behavioral assays, we demonstrate that spinal somatostatin-positive (SOM) excitatory interneurons transmit pruritic sensation. We found that the ablation of spinal SOM/Lbx1 (SOM) neurons caused significant attenuation of scratching responses evoked by various chemical pruritogens (chemical itch). In an attempt to identify substrates of spinal itch neural circuit, we observed that spinal SOM neurons partially overlapped with neurons expressing natriuretic peptide receptor A (Npra), the receptor of peripheral itch transmitter B-type natriuretic peptide. Spinal SOM neurons, however, did not show any overlap with itch transmission neurons expressing gastrin-releasing peptide receptor in the dorsal spinal cord, and the gastrin-releasing peptide-triggered scratching responses were intact after ablating spinal SOM neurons. Dual ablation of SOM and Npra neurons in the spinal cord reduced chemical itch responses to a greater extent than ablation of SOM or Npra neurons alone, suggesting the existence of parallel spinal pathways transmitting chemical itch. Furthermore, we showed that SOM peptide modulated itch processing through disinhibition of somatostatin receptor 2A-positive inhibitory interneuron. Together, our findings reveal a novel spinal mechanism for sensory encoding of itch perception.
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Liu J, Du J, Wang Y. CDK5 inhibits the clathrin-dependent internalization of TRPV1 by phosphorylating the clathrin adaptor protein AP2μ2. Sci Signal 2019; 12:12/585/eaaw2040. [PMID: 31186372 DOI: 10.1126/scisignal.aaw2040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1), a nonselective, ligand-gated cation channel, responds to multiple noxious stimuli and is targeted by many kinases that influence its trafficking and activity. Studies on the internalization of TRPV1 have mainly focused on that induced by capsaicin or other agonists. Here, we report that constitutive internalization of TRPV1 occurred in a manner dependent on clathrin, dynamin, and adaptor protein complex 2 (AP2). The μ2 subunit of AP2 (AP2μ2) interacted directly with TRPV1 and was required for its constitutive internalization. Cyclin-dependent kinase 5 (CDK5) phosphorylated AP2μ2 at Ser45, which reduced the interaction between TRPV1 and AP2μ2, leading to decreased TRPV1 internalization. Intrathecal delivery of a cell-penetrating fusion peptide corresponding to the Cdk5 phosphorylation site in AP2μ2, which competed with AP2μ2 for phosphorylation by Cdk5, increased the abundance of TRPV1 on the surface of dorsal root ganglion neurons and reduced complete Freund's adjuvant (CFA)-induced inflammatory thermal hyperalgesia in rats. In addition to describing a mechanism of TRPV1 constitutive internalization and its inhibition by CDK5, these findings demonstrate that CDK5 promotes inflammatory thermal hyperalgesia by reducing TRPV1 internalization, providing previously unidentified insights into the search for drug targets to treat pain.
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Affiliation(s)
- Jiao Liu
- Center of Medical and Health Analysis, Peking University Health Science Center, Beijing 100191, China.,Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, the Key Laboratory for Neuroscience of the Ministry of Education/National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China
| | - Junxia Du
- College of Biological Science and Engineering, Xingtai University, Xingtai 054001, Hebei Province, China
| | - Yun Wang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, the Key Laboratory for Neuroscience of the Ministry of Education/National Health Commission and State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China. .,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
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Abstract
Neuropathic itch is a pathological condition that is due to damage within the nervous system. This type of itch can be severe and unrelenting, which has a very negative impact on quality of life. Neuropathic itch is more common than generally appreciated because most types of neuropathic pain have a neuropathic itch counterpart. Unfortunately, much like neuropathic pain, there is a lack of effective treatments for neuropathic itch. Here, we consider the neural basis of itch and then describe how injuries within these neural circuits can lead to neuropathic itch in both animal models and human disease states.
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TRP Channels as Drug Targets to Relieve Itch. Pharmaceuticals (Basel) 2018; 11:ph11040100. [PMID: 30301231 PMCID: PMC6316386 DOI: 10.3390/ph11040100] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 09/26/2018] [Accepted: 10/03/2018] [Indexed: 12/14/2022] Open
Abstract
Although acute itch has a protective role by removing irritants to avoid further damage, chronic itch is debilitating, significantly impacting quality of life. Over the past two decades, a considerable amount of stimulating research has been carried out to delineate mechanisms of itch at the molecular, cellular, and circuit levels. There is growing evidence that transient receptor potential (TRP) channels play important roles in itch signaling. The purpose of this review is to summarize our current knowledge about the role of TRP channels in the generation of itch under both physiological and pathological conditions, thereby identifying them as potential drug targets for effective anti-itch therapies.
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40
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Zhang FX, Ge SN, Dong YL, Shi J, Feng YP, Li Y, Li YQ, Li JL. Vesicular glutamate transporter isoforms: The essential players in the somatosensory systems. Prog Neurobiol 2018; 171:72-89. [PMID: 30273635 DOI: 10.1016/j.pneurobio.2018.09.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/28/2018] [Accepted: 09/23/2018] [Indexed: 02/08/2023]
Abstract
In nervous system, glutamate transmission is crucial for centripetal conveyance and cortical perception of sensory signals of different modalities, which necessitates vesicular glutamate transporters 1-3 (VGLUT 1-3), the three homologous membrane-bound protein isoforms, to load glutamate into the presysnaptic vesicles. These VGLUTs, especially VGLUT1 and VGLUT2, selectively label and define functionally distinct neuronal subpopulations at each relay level of the neural hierarchies comprising spinal and trigeminal sensory systems. In this review, by scrutinizing each structure of the organism's fundamental hierarchies including dorsal root/trigeminal ganglia, spinal dorsal horn/trigeminal sensory nuclear complex, somatosensory thalamic nuclei and primary somatosensory cortex, we summarize and characterize in detail within each relay the neuronal clusters expressing distinct VGLUT protein/transcript isoforms, with respect to their regional distribution features (complementary distribution in some structures), axonal terminations/peripheral innervations and physiological functions. Equally important, the distribution pattern and characteristics of VGLUT1/VGLUT2 axon terminals within these structures are also epitomized. Finally, the correlation of a particular VGLUT isoform and its physiological role, disclosed thus far largely via studying the peripheral receptors, is generalized by referring to reports on global and conditioned VGLUT-knockout mice. Also, researches on VGLUTs relating to future direction are tentatively proposed, such as unveiling the elusive differences between distinct VGLUTs in mechanism and/or pharmacokinetics at ionic/molecular level, and developing VGLUT-based pain killers.
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Affiliation(s)
- Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Shun-Nan Ge
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yu-Lin Dong
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Juan Shi
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yu-Peng Feng
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yang Li
- Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PR China.
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China.
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Peripheral gabapentin regulates mosquito allergy-induced itch in mice. Eur J Pharmacol 2018; 833:44-49. [PMID: 29842875 DOI: 10.1016/j.ejphar.2018.05.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 11/24/2022]
Abstract
The antipruritic activity of gabapentin, an anticonvulsant, was studied in a mouse model of allergic itch. In mice sensitized by an extract of the salivary glands of the mosquito (ESGM), an intradermal injection of ESGM elicited scratching and increased peripheral nerve firing. Oral or intradermal administration of gabapentin at the ESGM injection site inhibited ESGM-induced scratching and peripheral nerve firing. However, gabapentin did not affect histamine-induced scratching. The distributions of immunoreactivity to the voltage-dependent calcium channel α2δ-1 subunit, a site of gabapentin action, and the histamine H1 receptor differed in the mouse dorsal root ganglia. The α2δ-1 subunit was mainly found in neurons that were 15-20 µm in diameter, whereas the H1 receptor was mainly in 20-30 µm neurons. In addition, α2δ-1 subunit immunoreactivity co-localized with that of transient receptor potential vanilloid 1 (TRPV1). These results suggest that gabapentin regulates allergic itch by acting on the calcium channel α2δ-1 subunit in peripheral TRPV1-positive neurons.
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42
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Nagy JI, Lynn BD, Senecal JMM, Stecina K. Connexin36 Expression in Primary Afferent Neurons in Relation to the Axon Reflex and Modality Coding of Somatic Sensation. Neuroscience 2018; 383:216-234. [PMID: 29746988 DOI: 10.1016/j.neuroscience.2018.04.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/02/2018] [Accepted: 04/26/2018] [Indexed: 01/25/2023]
Abstract
Electrical coupling mediated by connexin36-containing gap junctions that form electrical synapses is known to be prevalent in the central nervous system, but such coupling was long ago reported also to occur between cutaneous sensory fibers. Here, we provide evidence supporting the capability of primary afferent fibers to engage in electrical coupling. In transgenic mice with enhanced green fluorescent protein (eGFP) serving as a reporter for connexin36 expression, immunofluorescence labeling of eGFP was found in subpopulations of neurons in lumbar dorsal root and trigeminal sensory ganglia, and in fibers within peripheral nerves and tissues. Immunolabeling of connexin36 was robust in the sciatic nerve, weaker in sensory ganglia than in peripheral nerve, and absent in these tissues from Cx36 null mice. Connexin36 mRNA was detected in ganglia from wild-type mice, but not in those from Cx36 null mice. Labeling of eGFP was localized within a subpopulation of ganglion cells containing substance P and calcitonin gene-releasing peptide, and in peripheral fibers containing these peptides. Expression of eGFP was also found in various proportions of sensory ganglion neurons containing transient receptor potential (TRP) channels, including TRPV1 and TRPM8. Ganglion cells labeled for isolectin B4 and tyrosine hydroxylase displayed very little co-localization with eGFP. Our results suggest that previously observed electrical coupling between peripheral sensory fibers occurs via electrical synapses formed by Cx36-containing gap junctions, and that some degree of selectivity in the extent of electrical coupling may occur between fibers belonging to subpopulations of sensory neurons identified according to their sensory modality responsiveness.
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Affiliation(s)
- J I Nagy
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada.
| | - B D Lynn
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
| | - J M M Senecal
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
| | - K Stecina
- Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
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Abstract
Chronic, persistent itch is a devastating symptom that causes much suffering. In recent years, there has been great progress made in understanding the molecules, cells, and circuits underlying itch sensation. Once thought to be carried by pain-sensing neurons, itch is now believed to be capable of being transmitted by dedicated sensory labeled lines. Members of the Mas-related G protein-coupled receptor (Mrgpr) family demarcate an itch-specific labeled line in the peripheral nervous system. In the spinal cord, the expression of other proteins identifies additional populations of itch-dedicated sensory neurons. However, as evidence for labeled-line coding has mounted, studies promoting alternative itch-coding strategies have emerged, complicating our understanding of the neural basis of itch. In this review, we cover the molecules, cells, and circuits related to understanding the neural basis of itch, with a focus on the role of Mrgprs in mediating itch sensation.
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Affiliation(s)
- James Meixiong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA; ,
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA; , .,Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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44
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Kim YS, Kim SK, Lee JS, Ko SJ, Bae YC. Expression of vesicular glutamate transporters in transient receptor potential ankyrin 1 (TRPA1)-positive neurons in the rat trigeminal ganglion. Brain Res 2018; 1690:31-39. [DOI: 10.1016/j.brainres.2018.04.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 03/16/2018] [Accepted: 04/09/2018] [Indexed: 01/31/2023]
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45
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Zhang ZL, Yu G, Liang XN, Su RB, Gong ZH. Selective downregulation of vesicular glutamate transporter2 in ventral posterolateral nucleus of thalamus attenuates neuropathic mechanical allodynia in mice. Eur J Pharmacol 2018; 828:103-109. [PMID: 29605418 DOI: 10.1016/j.ejphar.2018.03.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 03/28/2018] [Accepted: 03/28/2018] [Indexed: 01/08/2023]
Abstract
Vesicular glutamate transporters (VGLUTs) transport glutamate into synaptic vesicles prior to exocytotic release. The expression pattern of VGLUT2 and studies of genetically modified mice have revealed that VGLUT2 contributes to neuropathic pain. We previously showed that VGLUT2 is upregulated in supraspinal regions including the thalamus in mice following spared nerve injury (SNI), and blocking VGLUTs using the VGLUT inhibitor CSB6B attenuated mechanical allodynia. To further evaluate the role of VGLUT2 in neuropathic pain, in this study, we developed a lentiviral vector expressing small hairpin RNAs (shRNAs) against mouse VGLUT2, which was injected into the ventral posterolateral (VPL) nucleus of the thalamus in the presence or absence of SNI. The administration of VGLUT2 shRNAs result in downregulation of VGLUT2 mRNA and protein expression, and decreased extracellular glutamate release in primary cultured neurons. We also showed that VGLUT2 shRNAs attenuated SNI-induced mechanical allodynia, in accordance with knockdown of VGLUT2 in the VPL nucleus in mice. Accordingly, our study supports the essential role of supraspinal VGLUT2 in neuropathic pain in adult mice and, thereby, validates VGLUT2 as a potential target for neuropathic pain therapy.
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Affiliation(s)
- Zhi-Ling Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China
| | - Gang Yu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China.
| | - Xiao-Nan Liang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China
| | - Rui-Bin Su
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China.
| | - Ze-Hui Gong
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27 Taiping Road, Beijing 100850, China
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46
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M N, J S, A M, R Y, Pal PK, P S. Reply to letter “Is Pruritus an indicator of Aquaporin-positive Neuromyelitis Optica?”. Mult Scler 2018; 24:1008-1009. [DOI: 10.1177/1352458517720530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Netravathi M
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Saini J
- Department of Neuroimaging and Interventional Neuroradiology (NIIR), National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Mahadevan A
- Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Yadav R
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - PK Pal
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
| | - Satishchandra P
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
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47
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Jiang YM, Huang C, Peng Z, Han SL, Li WG, Zhu MX, Xu TL. Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3. Mol Pain 2018; 13:1744806917721114. [PMID: 28745101 PMCID: PMC5533257 DOI: 10.1177/1744806917721114] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH2 (SL-NH2) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent application of SL-NH2 to the same site. Notably, co-application of acid and SL-NH2 following the initial injection of the pruritogen alone counteracted itch tachyphylaxis by augmenting the scratching behaviors in wild-type but not in acid-sensing ion channel 3-null, animals. Using an activity-dependent silencing strategy, we identified that acid-sensing ion channel 3-mediated itch enhancement mainly occurred via the Mas-related G-protein-coupled receptor C11-responsive sensory neurons. Together, our results indicate that acid-sensing ion channel 3, activated by concomitant acid and certain pruritogens, constitute a novel signaling pathway that counteracts itch tachyphylaxis to successive pruritogenic stimulation, which likely contributes to chronic itch associated with tissue acidosis.
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Affiliation(s)
- Yi-Ming Jiang
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Chen Huang
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhong Peng
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shao-Ling Han
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wei-Guang Li
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Michael Xi Zhu
- 2 Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, TX, USA
| | - Tian-Le Xu
- 1 Department of Anatomy and Physiology, Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Munanairi A, Liu XY, Barry DM, Yang Q, Yin JB, Jin H, Li H, Meng QT, Peng JH, Wu ZY, Yin J, Zhou XY, Wan L, Mo P, Kim S, Huo FQ, Jeffry J, Li YQ, Bardoni R, Bruchas MR, Chen ZF. Non-canonical Opioid Signaling Inhibits Itch Transmission in the Spinal Cord of Mice. Cell Rep 2018; 23:866-877. [PMID: 29669290 PMCID: PMC5937707 DOI: 10.1016/j.celrep.2018.03.087] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/28/2018] [Accepted: 03/20/2018] [Indexed: 01/20/2023] Open
Abstract
Chronic itch or pruritus is a debilitating disorder that is refractory to conventional anti-histamine treatment. Kappa opioid receptor (KOR) agonists have been used to treat chronic itch, but the underlying mechanism remains elusive. Here, we find that KOR and gastrin-releasing peptide receptor (GRPR) overlap in the spinal cord, and KOR activation attenuated GRPR-mediated histamine-independent acute and chronic itch in mice. Notably, canonical KOR-mediated Gαi signaling is not required for desensitizing GRPR function. In vivo and in vitro studies suggest that KOR activation results in the translocation of Ca2+-independent protein kinase C (PKC)δ from the cytosol to the plasma membrane, which in turn phosphorylates and inhibits GRPR activity. A blockade of phospholipase C (PLC) in HEK293 cells prevented KOR-agonist-induced PKCδ translocation and GRPR phosphorylation, suggesting a role of PLC signaling in KOR-mediated GRPR desensitization. These data suggest that a KOR-PLC-PKCδ-GRPR signaling pathway in the spinal cord may underlie KOR-agonists-induced anti-pruritus therapies.
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MESH Headings
- Animals
- Cell Membrane/metabolism
- Chloroquine/toxicity
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- HEK293 Cells
- Humans
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphorylation
- Protein Kinase C-delta/antagonists & inhibitors
- Protein Kinase C-delta/genetics
- Protein Kinase C-delta/metabolism
- Pruritus/chemically induced
- Pruritus/pathology
- RNA Interference
- RNA, Small Interfering/metabolism
- Receptors, Bombesin/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/deficiency
- Receptors, Opioid, kappa/genetics
- Signal Transduction
- Spinal Cord/metabolism
- Type C Phospholipases/antagonists & inhibitors
- Type C Phospholipases/metabolism
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Affiliation(s)
- Admire Munanairi
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xian-Yu Liu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Devin M Barry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qianyi Yang
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jun-Bin Yin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Hua Jin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hui Li
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Qing-Tao Meng
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jia-Hang Peng
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zhen-Yu Wu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Jun Yin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xuan-Yi Zhou
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Li Wan
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Ping Mo
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Seungil Kim
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Fu-Quan Huo
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Joseph Jeffry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yun-Qing Li
- Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PRC
| | - Rita Bardoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena 41125, Italy
| | - Michael R Bruchas
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zhou-Feng Chen
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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49
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Ji P, Chen L, Gong J, Yuan Y, Li M, Zhao Y, Zhang H. Co-expression of vasoactive intestinal peptide and protein gene product 9.5 surrounding the lumen of human Schlemm's canal. Exp Eye Res 2018; 170:1-7. [PMID: 29432726 DOI: 10.1016/j.exer.2018.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 02/08/2018] [Accepted: 02/08/2018] [Indexed: 01/20/2023]
Abstract
Previous studies of aqueous humor outflow have focused primarily on resistance at the trabecular meshwork (TM), and little is known about the function of Schlemm's canal (SC). Here, we aimed to investigate whether SC is innervated by the peripheral nervous system. Ten eye specimens from eight donors were processed for histological analysis. CD31 was used to identify SC, after which we used protein gene product (PGP) 9.5 as a marker to detect nerve fibers around SC. We then characterized the nerves by double staining for PGP9.5 and sympathetic nerve markers, such as tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DβH), or the parasympathetic marker vasoactive intestinal peptide (VIP), as well as sensory nerve marker calcitonin gene-related peptide (CGRP) and vesicular glutamate transporter 2 (VGLUT2). Immunohistochemistry and immunofluorescence were also performed to detect the expression of γ-epithelial Na+ channel (γ-ENaC) in SC. We found that different markers were expressed in the anterior chamber angle, with the luminal surface of SC were only positive stained for PGP9.5, VIP, and γ-ENaC. CGRP and VGLUT2 were expressed in TM and scleral spur (SS), whereas TH and DβH were absent in both TM and SC. Furthermore, PGP9.5 was co-expressed with VIP and γ-ENaC in the region surrounding the SC as well as in SS. Our findings indicate that the peripheral nerves anatomically spread in the tissues around the SC and the local nerve fibers may be parasympathetic or sensory rather than sympathetic.
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Affiliation(s)
- Pingting Ji
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China
| | - Liwen Chen
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China
| | - Jieling Gong
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China
| | - Yuxiang Yuan
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China
| | - Mu Li
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China
| | - Yin Zhao
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China.
| | - Hong Zhang
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, PR China.
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50
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Visceral pain - Novel approaches for optogenetic control of spinal afferents. Brain Res 2018; 1693:159-164. [PMID: 29425907 DOI: 10.1016/j.brainres.2018.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 01/22/2018] [Accepted: 02/01/2018] [Indexed: 11/21/2022]
Abstract
Painful stimuli arising within visceral organs are detected by peripheral nerve endings of spinal afferents, whose cell bodies are located in dorsal root ganglia (DRG). Recent technical advances have made it possible to reliably expose and inject single DRG with neuronal tracers or viruses in vivo. This has facilitated, for the first time, unequivocal identification of different types of spinal afferent endings in visceral organs. These technical advances paved the way for a very exciting series of in vivo experiments where individual DRG are injected to facilitate opsin expression (e.g. Archaerhodopsin). Organ-specific expression of opsins in sensory neurons may be achieved by retrograde viral transduction. This means activity of target-specific populations of sensory neurons, within single DRG, can be modulated by optogenetic photo-stimulation. Using this approach we implanted micro light-emitting diodes (micro-LEDs) adjacent to DRG of interest, thereby allowing focal DRG-specific control of visceral and/or somatic afferents in conscious mice. This is vastly different from broad photo-illumination of peripheral nerve endings, which are dispersed over much larger surface areas across an entire visceral organ; and embedded deep within multiple anatomical layers. Focal DRG photo-stimulation also avoids the potential that wide-field illumination of the periphery could inadvertently activate other closely apposed organs, or co-activate different classes of axons in the same organ (e.g. enteric and spinal afferent endings in the gut). It is now possible to selectively control nociceptive and/or non-nociceptive pathways to specific visceral organs in vivo, using wireless optogenetics and micro-LEDs implanted adjacent to DRG, for targeted photo-stimulation.
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