201
|
Pitake S, Debrecht J, Mishra SK. Brain natriuretic peptide (BNP) expressing sensory neurons are not involved in acute, inflammatory or neuropathic pain. Mol Pain 2018; 13:1744806917736993. [PMID: 28969473 PMCID: PMC5639968 DOI: 10.1177/1744806917736993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background We recently demonstrated that brain natriuretic peptide is expressed in the dorsal root ganglia, and that brain natriuretic peptide is required for normal detection of pruritogens. We further showed that the receptor for brain natriuretic peptide, natriuretic peptide receptor A, is present in the spinal cord, and elimination of these neurons profoundly attenuates scratching to itch-inducing compounds. However, the potential modulatory roles of brain natriuretic peptide in nociception, inflammation, and neuropathic mechanisms underlying the sensation of pain have not been investigated in detail. Findings To demonstrate the involvement of brain natriuretic peptide in pain, we compared the behavioral responses of brain natriuretic peptide knockout mice with their wild-type littermates. First, we showed that brain natriuretic peptide is not required in chemically induced pain responses evoked by the administration of capsaicin, allyl isothiocyanate, adenosine 5′-triphosphate, or inflammatory soup. We further measured pain behaviors and found no involvement of brain natriuretic peptide in hot, cold, or mechanical nociceptive responses in mice, nor did we find evidence for the involvement of brain natriuretic peptide in neuroinflammatory sensitization elicited by complete Freund’s adjuvant or in neuropathic pain. Conclusions These results demonstrate that brain natriuretic peptide is not essential for pain-related behaviors.
Collapse
Affiliation(s)
- Saumitra Pitake
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine (CVM), NC State University
| | - Jennifer Debrecht
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine (CVM), NC State University
| | | |
Collapse
|
202
|
Katayama Y, Sakamoto T, Takanami K, Takei Y. The Amphibious Mudskipper: A Unique Model Bridging the Gap of Central Actions of Osmoregulatory Hormones Between Terrestrial and Aquatic Vertebrates. Front Physiol 2018; 9:1112. [PMID: 30154735 PMCID: PMC6102947 DOI: 10.3389/fphys.2018.01112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/25/2018] [Indexed: 12/15/2022] Open
Abstract
Body fluid regulation, or osmoregulation, continues to be a major topic in comparative physiology, and teleost fishes have been the subject of intensive research. Great progress has been made in understanding the osmoregulatory mechanisms including drinking behavior in teleosts and mammals. Mudskipper gobies can bridge the gap from aquatic to terrestrial habitats by their amphibious behavior, but the studies are yet emerging. In this review, we introduce this unique teleost as a model to study osmoregulatory behaviors, particularly amphibious behaviors regulated by the central action of hormones. Regarding drinking behavior of mammals, a thirst sensation is aroused by angiotensin II (Ang II) through direct actions on the forebrain circumventricular structures, which predominantly motivates them to search for water and take it into the mouth for drinking. By contrast, aquatic teleosts can drink water that is constantly present in their mouth only by reflex swallowing, and Ang II induces swallowing by acting on the hindbrain circumventricular organ without inducing thirst. In mudskippers, however, through the loss of buccal water by swallowing, which appears to induce buccal drying on land, Ang II motivates these fishes to move to water for drinking. Thus, mudskippers revealed a unique thirst regulation by sensory detection in the buccal cavity. In addition, the neurohypophysial hormones, isotocin (IT) and vasotocin (VT), promote migration to water via IT receptors in mudskippers. VT is also dipsogenic and the neurons in the forebrain may mediate their thirst. VT regulates social behaviors as well as osmoregulation. The VT-induced migration appears to be a submissive response of subordinate mudskippers to escape from competitive and dehydrating land. Together with implications of VT in aggression, mudskippers may bridge the multiple functions of neurohypophysial hormones. Interestingly, cortisol, an important hormone for seawater adaptation and stress response in teleosts, also stimulates the migration toward water, mediated possibly via the mineralocorticoid receptor. The corticosteroid system that is responsive to external stressors can accelerate emergence of migration to alternative habitats. In this review, we suggest this unique teleost as an important model to deepen insights into the behavioral roles of these hormones in relation to osmoregulation.
Collapse
Affiliation(s)
- Yukitoshi Katayama
- Physiology Section, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute, Faculty of Science, Okayama University, Setouchi, Japan
| | - Keiko Takanami
- Ushimado Marine Institute, Faculty of Science, Okayama University, Setouchi, Japan.,Mouse Genomics Resource Laboratory, National Institute of Genetics, Mishima, Japan
| | - Yoshio Takei
- Physiology Section, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| |
Collapse
|
203
|
Sun XY, Sun LL, Qi H, Gao Q, Wang GX, Wei NN, Wang K. Antipruritic Effect of Natural Coumarin Osthole through Selective Inhibition of Thermosensitive TRPV3 Channel in the Skin. Mol Pharmacol 2018; 94:1164-1173. [PMID: 30108138 DOI: 10.1124/mol.118.112466] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/16/2018] [Indexed: 12/14/2022] Open
Abstract
Coumarin osthole is a dominant bioactive ingredient of the natural Cnidium monnieri plant commonly used for traditional Chinese herbal medicines for therapies and treatments including antipruritus and antidermatitis. However, the molecular mechanism underlying the action of osthole remains unclear. In this study, we report that osthole exerts an antipruritic effect through selective inhibition of Ca2+-permeable and thermosensitive transient receptor potential vanilloid 3 (TRPV3) cation channels that are primarily expressed in the keratinocytes of the skin. Coumarin osthole was identified as an inhibitor of TRPV3 channels transiently expressed in HEK293 cells in a calcium fluorescent assay. Inhibition of the TRPV3 current by osthole and its selectivity were further confirmed by whole-cell patch clamp recordings of TRPV3-expressing HEK293 cells and mouse primary cultured keratinocytes. Behavioral evaluation demonstrated that inhibition of TRPV3 by osthole or silencing by knockout of the TRPV3 gene significantly reduced the scratching induced by either acetone-ether-water or histamine in localized rostral neck skin in mice. Taken together, our findings provide a molecular basis for use of natural coumarin osthole from the C. monnieri plant in antipruritic or skin care therapy, thus establishing a significant role of the TRPV3 channel in chronic itch signaling or acute histamine-dependent itch sensation.
Collapse
Affiliation(s)
- Xiao-Ying Sun
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Li-Lan Sun
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Hang Qi
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Qin Gao
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Gong-Xin Wang
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Ning-Ning Wei
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - KeWei Wang
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| |
Collapse
|
204
|
Ralvenius WT, Neumann E, Pagani M, Acuña MA, Wildner H, Benke D, Fischer N, Rostaher A, Schwager S, Detmar M, Frauenknecht K, Aguzzi A, Hubbs JL, Rudolph U, Favrot C, Zeilhofer HU. Itch suppression in mice and dogs by modulation of spinal α2 and α3GABA A receptors. Nat Commun 2018; 9:3230. [PMID: 30104684 PMCID: PMC6089996 DOI: 10.1038/s41467-018-05709-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/20/2018] [Indexed: 11/10/2022] Open
Abstract
Chronic itch is a highly debilitating condition affecting about 10% of the general population. The relay of itch signals is under tight control by inhibitory circuits of the spinal dorsal horn, which may offer a hitherto unexploited therapeutic opportunity. Here, we found that specific pharmacological targeting of inhibitory α2 and α3GABAA receptors reduces acute histaminergic and non-histaminergic itch in mice. Systemic treatment with an α2/α3GABAA receptor selective modulator alleviates also chronic itch in a mouse model of atopic dermatitis and in dogs sensitized to house dust mites, without inducing sedation, motor dysfunction, or loss of antipruritic activity after prolonged treatment. Transsynaptic circuit tracing, immunofluorescence, and electrophysiological experiments identify spinal α2 and α3GABAA receptors as likely molecular targets underlying the antipruritic effect. Our results indicate that drugs targeting α2 and α3GABAA receptors are well-suited to alleviate itch, including non-histaminergic chronic itch for which currently no approved treatment exists.
Collapse
Affiliation(s)
- William T Ralvenius
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Elena Neumann
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Martina Pagani
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.,Drug Discovery Network Zürich (DDNZ), Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Nina Fischer
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Ana Rostaher
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Simon Schwager
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Michael Detmar
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Katrin Frauenknecht
- Institute of Neuropathology, University of Zürich and University Hospital Zürich, Schmelzbergstrasse 12, CH-8091, Zürich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zürich and University Hospital Zürich, Schmelzbergstrasse 12, CH-8091, Zürich, Switzerland
| | - Jed Lee Hubbs
- Laboratory of Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, 115 Mill Street, Belmont, MA, 02478, USA.,Department of Psychiatry, Harvard Medical School, 401 Park Drive, Boston, MA, 02215, USA
| | - Claude Favrot
- Dermatology Department, Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, Winterthurerstrasse 260, CH-8057, Zürich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Neuroscience Center Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Drug Discovery Network Zürich (DDNZ), Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, CH-8093, Zürich, Switzerland.
| |
Collapse
|
205
|
Han Q, Liu D, Convertino M, Wang Z, Jiang C, Kim YH, Luo X, Zhang X, Nackley A, Dokholyan NV, Ji RR. miRNA-711 Binds and Activates TRPA1 Extracellularly to Evoke Acute and Chronic Pruritus. Neuron 2018; 99:449-463.e6. [PMID: 30033153 DOI: 10.1016/j.neuron.2018.06.039] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 04/04/2018] [Accepted: 06/25/2018] [Indexed: 01/02/2023]
Abstract
Increasing evidence suggests that extracellular miRNAs may serve as biomarkers of diseases, but the physiological relevance of extracellular miRNA is unclear. We find that intradermal cheek injection of miR-711 induces TRPA1-depedent itch (scratching) without pain (wiping) in naive mice. Extracellular perfusion of miR-711 induces TRPA1 currents in both Trpa1-expressing heterologous cells and native sensory neurons through the core sequence GGGACCC. Computer simulations reveal that the core sequence binds several residues at the extracellular S5-S6 loop of TRPA1, which are critical for TRPA1 activation by miR-711 but not allyl isothiocyanate. Intradermal inoculation of human Myla cells induces lymphoma and chronic itch in immune-deficient mice, associated with increased serum levels of miR-711, secreted from cancer cells. Lymphoma-induced chronic itch is suppressed by miR-711 inhibitor and a blocking peptide that disrupts the miR-711/TRPA1 interaction. Our findings demonstrated an unconventional physiological role of extracellular naked miRNAs as itch mediators and ion channel modulators.
Collapse
Affiliation(s)
- Qingjian Han
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Di Liu
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Marino Convertino
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Zilong Wang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Changyu Jiang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yong Ho Kim
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Xin Luo
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Xin Zhang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Andrea Nackley
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
| |
Collapse
|
206
|
Steinhoff M, Schmelz M, Szabó IL, Oaklander AL. Clinical presentation, management, and pathophysiology of neuropathic itch. Lancet Neurol 2018; 17:709-720. [PMID: 30033061 DOI: 10.1016/s1474-4422(18)30217-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 05/15/2018] [Accepted: 06/01/2018] [Indexed: 12/19/2022]
Abstract
Unlike conventional itch, neuropathic itch develops in normal skin from excess peripheral firing or dampened central inhibition of itch pathway neurons. Neuropathic itch is a symptom of the same central and peripheral nervous system disorders that cause neuropathic pain, such as sensory polyneuropathy, radiculopathy, herpes zoster, stroke, or multiple sclerosis, and lesion location affects symptoms more than aetiology. The causes of neuropathic itch are heterogeneous, and thus diagnosis is based primarily on recognising characteristic, disease-specific clinical presentations. However, the diagnosis of neuropathic itch is challenging, different subforms exist (eg, focal vs widespread, peripheral vs central), and the mechanisms of neuropathic itch are poorly understood, resulting in reduced treatment availability. Currently available strategies include treating or preventing causal diseases, such as diabetes or herpes zoster, and topical or systemic medications that calm excess neuronal firing. Discovery of itch mediators such as gastrin releasing peptide, receptors (eg, neurokinin-1), and pathways (eg, Janus kinases) might encourage much needed new research into targeted treatments of neuropathic itch.
Collapse
Affiliation(s)
- Martin Steinhoff
- Department of Dermatology and Venereology, Hamad Medical Corporation, Doha, Qatar; HMC Translational Research Institute, Hamad Medical Corporation, Doha, Qatar; Weill Cornell Medicine-Qatar, Doha, Qatar; College of Medicine, Qatar University, Medical School, Doha, Qatar.
| | - Martin Schmelz
- Department of Experimental Pain Research, CBTM Mannheim, Heidelberg University, Mannheim, Germany
| | - Imre Lőrinc Szabó
- Department of Dermatology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Anne Louise Oaklander
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Neuropathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
207
|
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.
Collapse
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
| |
Collapse
|
208
|
Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
Collapse
Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
| |
Collapse
|
209
|
Abstract
The mechanisms by which noxious stimuli produce the sensation of pain in animals are complex. Noxious stimuli are transduced at the periphery and transmitted to the CNS, where this information is subject to considerable modulation. Finally, the information is projected to the brain where it is perceived as pain. Additionally, plasticity can develop in the pain pathway and hyperalgesia and allodynia may develop through sensitisation both peripherally and centrally. A large number of different ion channels, receptors, and cell types are involved in pain perception, and it is hoped that through a better understanding of these, new and refined treatments for pain will result.
Collapse
Affiliation(s)
- A Bell
- School of Veterinary Medicine, University of Glasgow, Glasgow, G61 1QH, UK.
| |
Collapse
|
210
|
Deletion of Tsc2 in Nociceptors Reduces Target Innervation, Ion Channel Expression, and Sensitivity to Heat. eNeuro 2018; 5:eN-NWR-0436-17. [PMID: 29766046 PMCID: PMC5952427 DOI: 10.1523/eneuro.0436-17.2018] [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] [Received: 12/13/2017] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is known to regulate cellular growth pathways, and its genetic activation is sufficient to enhance regenerative axon growth following injury to the central or peripheral nervous systems. However, excess mTORC1 activation may promote innervation defects, and mTORC1 activity mediates injury-induced hypersensitivity, reducing enthusiasm for the pathway as a therapeutic target. While mTORC1 activity is required for full expression of some pain modalities, the effects of pathway activation on nociceptor phenotypes and sensory behaviors are currently unknown. To address this, we genetically activated mTORC1 in mouse peripheral sensory neurons by conditional deletion of its negative regulator Tuberous Sclerosis Complex 2 (Tsc2). Consistent with the well-known role of mTORC1 in regulating cell size, soma size and axon diameter of C-nociceptors were increased in Tsc2-deleted mice. Glabrous skin and spinal cord innervation by C-fiber neurons were also disrupted. Transcriptional profiling of nociceptors enriched by fluorescence-associated cell sorting (FACS) revealed downregulation of multiple classes of ion channels as well as reduced expression of markers for peptidergic nociceptors in Tsc2-deleted mice. In addition to these changes in innervation and gene expression, Tsc2-deleted mice exhibited reduced noxious heat sensitivity and decreased injury-induced cold hypersensitivity, but normal baseline sensitivity to cold and mechanical stimuli. Together, these data show that excess mTORC1 activity in sensory neurons produces changes in gene expression, neuron morphology and sensory behavior.
Collapse
|
211
|
Braz JM, Etlin A, Juarez-Salinas D, Llewellyn-Smith IJ, Basbaum AI. Rebuilding CNS inhibitory circuits to control chronic neuropathic pain and itch. PROGRESS IN BRAIN RESEARCH 2018; 231:87-105. [PMID: 28554402 DOI: 10.1016/bs.pbr.2016.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cell transplantation offers an attractive alternative to pharmacotherapy for the management of a host of clinical conditions. Most importantly, the transplanted cells provide a continuous, local delivery of therapeutic compounds, which avoids many of the adverse side effects associated with systemically administered drugs. Here, we describe the broad therapeutic utility of transplanting precursors of cortical inhibitory interneurons derived from the embryonic medial ganglionic eminence (MGE), in a variety of chronic pain and itch models in the mouse. Despite the cortical environment in which the MGE cells normally develop, these cells survive transplantation and will even integrate into the circuitry of an adult host spinal cord. When transplanted into the spinal cord, the cells significantly reduce the hyperexcitability that characterizes both chronic neuropathic pain and itch conditions. This MGE cell-based strategy differs considerably from traditional pharmacological treatments as the approach is potentially disease modifying (i.e., the therapy targets the underlying etiology of the pain and itch pathophysiology).
Collapse
Affiliation(s)
- Joao M Braz
- University of California-San Francisco, San Francisco, CA, United States
| | - Alex Etlin
- University of California-San Francisco, San Francisco, CA, United States
| | | | - Ida J Llewellyn-Smith
- Cardiovascular Medicine, Human Physiology and Centre for Neuroscience, Flinders University, Bedford Park, SA, Australia
| | - Allan I Basbaum
- University of California-San Francisco, San Francisco, CA, United States.
| |
Collapse
|
212
|
Huang J, Polgár E, Solinski HJ, Mishra SK, Tseng PY, Iwagaki N, Boyle KA, Dickie AC, Kriegbaum MC, Wildner H, Zeilhofer HU, Watanabe M, Riddell JS, Todd AJ, Hoon MA. Circuit dissection of the role of somatostatin in itch and pain. Nat Neurosci 2018; 21:707-716. [PMID: 29556030 PMCID: PMC5923877 DOI: 10.1038/s41593-018-0119-z] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 01/25/2018] [Indexed: 11/09/2022]
Abstract
Stimuli that elicit itch are detected by sensory neurons that innervate the skin. This information is processed by the spinal cord; however, the way in which this occurs is still poorly understood. Here we investigated the neuronal pathways for itch neurotransmission, particularly the contribution of the neuropeptide somatostatin. We find that in the periphery, somatostatin is exclusively expressed in Nppb+ neurons, and we demonstrate that Nppb+somatostatin+ cells function as pruriceptors. Employing chemogenetics, pharmacology and cell-specific ablation methods, we demonstrate that somatostatin potentiates itch by inhibiting inhibitory dynorphin neurons, which results in disinhibition of GRPR+ neurons. Furthermore, elimination of somatostatin from primary afferents and/or from spinal interneurons demonstrates differential involvement of the peptide released from these sources in itch and pain. Our results define the neural circuit underlying somatostatin-induced itch and characterize a contrasting antinociceptive role for the peptide.
Collapse
Affiliation(s)
- Jing Huang
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
- Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, PR China
| | - Erika Polgár
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Hans Jürgen Solinski
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
| | - Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University; and Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
| | - Pang-Yen Tseng
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
| | - Noboru Iwagaki
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Kieran A Boyle
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Allen C Dickie
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Mette C Kriegbaum
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich; and Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich; and Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Zürich, Switzerland
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - John S Riddell
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Andrew J Todd
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, MD, USA.
| |
Collapse
|
213
|
Chamessian A, Young M, Qadri Y, Berta T, Ji RR, Van de Ven T. Transcriptional Profiling of Somatostatin Interneurons in the Spinal Dorsal Horn. Sci Rep 2018; 8:6809. [PMID: 29717160 PMCID: PMC5931607 DOI: 10.1038/s41598-018-25110-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/13/2018] [Indexed: 01/08/2023] Open
Abstract
The spinal dorsal horn (SDH) is comprised of distinct neuronal populations that process different somatosensory modalities. Somatostatin (SST)-expressing interneurons in the SDH have been implicated specifically in mediating mechanical pain. Identifying the transcriptomic profile of SST neurons could elucidate the unique genetic features of this population and enable selective analgesic targeting. To that end, we combined the Isolation of Nuclei Tagged in Specific Cell Types (INTACT) method and Fluorescence Activated Nuclei Sorting (FANS) to capture tagged SST nuclei in the SDH of adult male mice. Using RNA-sequencing (RNA-seq), we uncovered more than 13,000 genes. Differential gene expression analysis revealed more than 900 genes with at least 2-fold enrichment. In addition to many known dorsal horn genes, we identified and validated several novel transcripts from pharmacologically tractable functional classes: Carbonic Anhydrase 12 (Car12), Phosphodiesterase 11 A (Pde11a), and Protease-Activated Receptor 3 (F2rl2). In situ hybridization of these novel genes showed differential expression patterns in the SDH, demonstrating the presence of transcriptionally distinct subpopulations within the SST population. Overall, our findings provide new insights into the gene repertoire of SST dorsal horn neurons and reveal several novel targets for pharmacological modulation of this pain-mediating population and treatment of pathological pain.
Collapse
Affiliation(s)
- Alexander Chamessian
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, 27710, USA. .,Medical Scientist Training Program, Duke University School of Medicine, Durham, North Carolina, 27710, USA. .,Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, 27710, USA.
| | - Michael Young
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Yawar Qadri
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Temugin Berta
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267, USA
| | - Ru-Rong Ji
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, 27710, USA.,Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| | - Thomas Van de Ven
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
| |
Collapse
|
214
|
Pruritus: Progress toward Pathogenesis and Treatment. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9625936. [PMID: 29850592 PMCID: PMC5925168 DOI: 10.1155/2018/9625936] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 01/15/2018] [Accepted: 02/11/2018] [Indexed: 02/06/2023]
Abstract
Pruritus, the most common cutaneous symptom, is widely seen in many skin complaints. It is an uncomfortable feeling on the skin and sometimes impairs patients' quality of life. At present, the specific mechanism of pruritus still remains unclear. Antihistamines, which are usually used to relieve pruritus, ineffectively work in some patients with itching. Recent evidence has suggested that, apart from histamine, many mediators and signaling pathways are involved in the pathogenesis of pruritus. Various therapeutic options for itching correspondingly have been developed. In this review, we summarize the updated pathogenesis and therapeutic strategies for pruritus.
Collapse
|
215
|
Antidromic neurogenic activity and cutaneous bacterial flora. Semin Immunopathol 2018; 40:281-289. [DOI: 10.1007/s00281-018-0671-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 03/06/2018] [Indexed: 12/13/2022]
|
216
|
Abstract
Itch is an unpleasant sensation that initiates scratching behavior. The itch-scratch reaction is a complex phenomenon that implicates supraspinal structures required for regulation of sensory, emotional, cognitive, and motivational aspects. However, the central mechanisms underlying the processing of itch and the interplay of the supraspinal regions and spinal cord in regulating itch-scratch processes are poorly understood. Here, we have shown that the neural projections from anterior cingulate cortex (ACC) to dorsal medial striatum (DMS) constitute a critical circuit element for regulating itch-related behaviors in the brains of male C57BL/6J mice. Moreover, we demonstrate that ACC-DMS projections selectively modulate histaminergic, but not nonhistaminergic, itch-related behavior. Furthermore, photoactivation of ACC-DMS projections has also no significant effects on pain behavior induced by thermal, mechanical, and chemical stimuli except for a relief on inflammatory pain evoked by formalin and complete Freund's adjuvant. We further demonstrate that the dorsal spinal cord exerts an inhibitory effect on itch signal from ACC-DMS projections through B5-I neurons, which represent a population of spinal inhibitory interneurons that mediate the inhibition of itch. Therefore, this study presents the first evidence that the ACC-DMS projections modulate histaminergic itch-related behavior and reveals an interplay between the supraspinal and spinal levels in histaminergic itch regulation.SIGNIFICANCE STATEMENT This study reveals that the projections from anterior cingulate cortex (ACC) to dorsal medial striatum (DMS) constitute a supraspinal circuit for modulation of histaminergic, but not nonhistaminergic, itch. Manipulation of ACC-DMS projections has no effect on acute pain sensation. Furthermore, the dorsal spinal cord exerts an inhibitory effect on itch signal from ACC-DMS projections through B5-I neurons. Understanding the supraspinal itch circuits is of great significance in the development of new therapies for chronic itch-related intractable diseases.
Collapse
|
217
|
Cui TT, Wang GX, Wei NN, Wang K. A pivotal role for the activation of TRPV3 channel in itch sensations induced by the natural skin sensitizer carvacrol. Acta Pharmacol Sin 2018; 39:331-335. [PMID: 29094727 DOI: 10.1038/aps.2017.152] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/26/2017] [Indexed: 01/10/2023] Open
Abstract
Itching is an intricate, common symptom of dermatologic and systemic diseases, and both TRPV3 and TRPA1 channels have been suggested to function as downstream effector targets. But the relative contributions of TRPV3 and TRPA1 to itch sensation in vivo remain unclear. To dissect the role of TRPA1 or TRPV3 in the cutaneous sensation of itching, we took the advantage of a natural compound carvacrol from oregano, and examined its effect on the induction of scratching behavior in mice. We showed that the intradermal injection of carvacrol (0.01%, 0.1% and 1%, 50 μL) induced scratching in a concentration-dependent manner. But in TRPV3-knockout mice, the scratching induced by carvacrol (1%, 50 μL) was markedly decreased by approximately 64% (from 275 scratching bouts down to 90) within 60 min. Further analysis revealed that TRPV3-knockout caused a reduction of scratching bouts for approximately 40% in the first 20 min (the initial phase), whereas the scratching bouts were reduced by approximately 90% in the last 40 min (the sustained phase). These results were in consistence with those in our whole-cell recordings in HEK-293T cells expressing either TRPA1 or TRPV3: carvacrol exhibited similar potencies in activating either TRPA1 or TRPV3, but carvacrol-activated TRPA1 current showed a rapid desensitization, which was reduced by approximately 90% within 5 min before a complete washout, whereas carvacrol-induced TRPV3 current showed a slow desensitization that caused less than 30% of current reduction in 10 min and left a significant residual TRPV3 current after washout. Our results demonstrate that carvacrol from plant oregano is a skin sensitizer or allergen; TRPV3 is involved in the initial phase and the sustained phase of pruritus, whereas TRPA1 likely contributes to the initial phase.
Collapse
|
218
|
Sathyamurthy A, Johnson KR, Matson KJE, Dobrott CI, Li L, Ryba AR, Bergman TB, Kelly MC, Kelley MW, Levine AJ. Massively Parallel Single Nucleus Transcriptional Profiling Defines Spinal Cord Neurons and Their Activity during Behavior. Cell Rep 2018; 22:2216-2225. [PMID: 29466745 PMCID: PMC5849084 DOI: 10.1016/j.celrep.2018.02.003] [Citation(s) in RCA: 221] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/19/2017] [Accepted: 01/30/2018] [Indexed: 01/08/2023] Open
Abstract
To understand the cellular basis of behavior, it is necessary to know the cell types that exist in the nervous system and their contributions to function. Spinal networks are essential for sensory processing and motor behavior and provide a powerful system for identifying the cellular correlates of behavior. Here, we used massively parallel single nucleus RNA sequencing (snRNA-seq) to create an atlas of the adult mouse lumbar spinal cord. We identified and molecularly characterized 43 neuronal populations. Next, we leveraged the snRNA-seq approach to provide unbiased identification of neuronal populations that were active following a sensory and a motor behavior, using a transcriptional signature of neuronal activity. This approach can be used in the future to link single nucleus gene expression data with dynamic biological responses to behavior, injury, and disease.
Collapse
Affiliation(s)
- Anupama Sathyamurthy
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Kory R Johnson
- Bioinformatics Section, Information Technology Program, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Kaya J E Matson
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Courtney I Dobrott
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Li Li
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Anna R Ryba
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Tzipporah B Bergman
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
| | - Michael C Kelly
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Matthew W Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, Bethesda, MD 20892, USA
| | - Ariel J Levine
- Spinal Circuits and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.
| |
Collapse
|
219
|
Steinhoff M, Buddenkotte J, Lerner EA. Role of mast cells and basophils in pruritus. Immunol Rev 2018; 282:248-264. [DOI: 10.1111/imr.12635] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Martin Steinhoff
- Department of Dermatology and Venereology; Hamad Medical Corporation; Doha Qatar
- Translational Research Institute; Hamad Medical Corporation; Doha Qatar
- Weill Cornell Medicine-Qatar; Doha Qatar
- Medical School; Qatar University; Doha Qatar
- Department Of Dermatology and UCD Charles Institute for Translational Dermatology; University College Dublin; Dublin Ireland
| | - Jörg Buddenkotte
- Department of Dermatology and Venereology; Hamad Medical Corporation; Doha Qatar
- Translational Research Institute; Hamad Medical Corporation; Doha Qatar
| | - Ethan A. Lerner
- Cutaneous Biology Research Center; Department of Dermatology; Massachusetts General Hospital/Harvard Medical School; Charlestown MA USA
| |
Collapse
|
220
|
New mechanism underlying IL-31-induced atopic dermatitis. J Allergy Clin Immunol 2018; 141:1677-1689.e8. [PMID: 29427643 DOI: 10.1016/j.jaci.2017.12.1002] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/18/2017] [Accepted: 12/21/2017] [Indexed: 01/10/2023]
Abstract
BACKGROUND TH2 cell-released IL-31 is a critical mediator in patients with atopic dermatitis (AD), a prevalent and debilitating chronic skin disorder. Brain-derived natriuretic peptide (BNP) has been described as a central itch mediator. The importance of BNP in peripheral (skin-derived) itch and its functional link to IL-31 within the neuroimmune axis of the skin is unknown. OBJECTIVE We sought to investigate the function of BNP in the peripheral sensory system and skin in IL-31-induced itch and neuroepidermal communication in patients with AD. METHODS Ca2+ imaging, immunohistochemistry, quantitative real-time PCR, RNA sequencing, knockdown, cytokine/phosphokinase arrays, enzyme immune assay, and pharmacologic inhibition were performed to examine the cellular basis of the IL-31-stimulated, BNP-related itch signaling in dorsal root ganglionic neurons (DRGs) and skin cells, transgenic AD-like mouse models, and human skin of patients with AD and healthy subjects. RESULTS In human DRGs we confirmed expression and co-occurrence of oncostatin M receptor β subunit and IL-31 receptor A in a small subset of the neuronal population. Furthermore, IL-31 activated approximately 50% of endothelin-1-responsive neurons, and half of the latter also responded to histamine. In murine DRGs IL-31 upregulated Nppb and induced soluble N-ethylmaleimide-sensitive factor activating protein receptor-dependent BNP release. In Grhl3PAR2/+ mice house dust mite-induced severe AD-like dermatitis was associated with Nppb upregulation. Lesional IL-31 transgenic mice also exhibited increased Nppb transcripts in DRGs and the skin; accordingly, skin BNP receptor levels were increased. Importantly, expression of BNP and its receptor were increased in the skin of patients with AD. In human skin cells BNP stimulated a proinflammatory and itch-promoting phenotype. CONCLUSION For the first time, our findings show that BNP is implicated in AD and that IL-31 regulates BNP in both DRGs and the skin. IL-31 enhances BNP release and synthesis and orchestrates cytokine and chemokine release from skin cells, thereby coordinating the signaling pathways involved in itch. Inhibiting peripheral BNP function might be a novel therapeutic strategy for AD and pruritic conditions.
Collapse
|
221
|
Epigallocatechin-3-gallate attenuates acute and chronic psoriatic itch in mice: Involvement of antioxidant, anti-inflammatory effects and suppression of ERK and Akt signaling pathways. Biochem Biophys Res Commun 2018; 496:1062-1068. [PMID: 29402411 DOI: 10.1016/j.bbrc.2018.01.122] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 01/19/2018] [Indexed: 01/12/2023]
Abstract
Chronic itch is a distressing symptom of many skin diseases and negatively impacts quality of life. However, there is no medication for most forms of chronic itch, although antihistamines are often used for anti-itch treatment. Epigallocatechin-3-gallate (EGCG), a major green tea polyphenol, exhibits anti-oxidative and anti-inflammatory properties. Our previous studies highlighted a key role of oxidative stress and proinflammatory cytokines in acute and chronic itch. Here, we evaluated the effects of green tea polyphenon 60 and EGCG on acute and chronic itch in mouse models and explored its potential mechanisms. The effects of EGCG were determined by behavioral tests in mouse models of acute and chronic itch, which were induced by compound 48/80, chloroquine (CQ), and 5% imiquimod cream treatment, respectively. We found that systemic or local administration of green tea polyphenon 60 or EGCG significantly alleviated compound 48/80- and chloroquine-induced acute itch in a dose-dependent manner in mice. Incubation of EGCG significantly decreased the accumulation of intracellular reactive oxygen species (ROS) directly induced by compound 48/80 and CQ in cultured ND7-23 cells, a dorsal root ganglia derived cell line. EGCG also attenuated imiquimod-induced chronic psoriatic itch behaviors and skin epidermal hyperplasia in mice. In addition, EGCG inhibited the expression of IL-23 mRNA in skin and TRPV1 mRNA in dorsal root ganglia (DRG). Finally, EGCG remarkably inhibited compound 48/80-induced phosphorylation of extracellular signal-regulated kinase (ERK) and imiquimod-induced p-AKT in the spinal cord of mice, respectively. Collectively, these results indicated EGCG could be a promising strategy for anti-itch therapy.
Collapse
|
222
|
Qu X, Wang H, Liu R. Recent insights into biological functions of mammalian bombesin-like peptides and their receptors. Curr Opin Endocrinol Diabetes Obes 2018; 25:36-41. [PMID: 29120926 DOI: 10.1097/med.0000000000000375] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW The current review highlights recent advances in physiological and pharmacological researches in biology of mammalian bombesin-like peptides (BLPs). RECENT FINDINGS BLPs and their receptors were found to have regulatory roles in many biological processes in central nervous system. Two BLPs, neuromedin B and gastrin-releasing peptide (GRP), and their receptors are required for regulation of basal and induced sighing activity in rodents. This is the first study demonstrating central pathways involved in regulation of sighing activity. GRP receptor (GRPR) expressing neurons are excitatory glutamatergic interneurons located in the dorsal lamina without projections outside the spinal cord and mediate itch signals via vesicular glutamate transporter 2. Those neurons receive itch signals and make synapses with the parabrachial nucleus projecting spinal neurons to transmit itch signals to parabrachial nucleus. GRP expressing interneurons function in a proposed 'leaky gate model' to interpret the mechanism of both pain and itch transmission. In addition to recent advances of biology in nervous system, BLPs and their receptors were found to play potential regulatory roles in innate and adaptive immune responses and tissue development. SUMMARY Several important biological roles of BLPs and their receptors in nervous system were identified. Together with researches regarding central roles of BLPs, studies revealing the regulatory roles of BLPs and their receptors in immunology and tissue development provide us with novel insights into understanding of the biology of BLPs and their receptors.
Collapse
Affiliation(s)
- Xiangping Qu
- Department of Physiology, Xiangya School of Medicine, Central South University, Changsha, Hunan, PR China
| | | | | |
Collapse
|
223
|
Preprotachykinin A is expressed by a distinct population of excitatory neurons in the mouse superficial spinal dorsal horn including cells that respond to noxious and pruritic stimuli. Pain 2017; 158:440-456. [PMID: 27902570 PMCID: PMC5302415 DOI: 10.1097/j.pain.0000000000000778] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Expression of the substance P precursor preprotachykinin A defines a distinct population of superficial dorsal horn excitatory neurons, many of which respond to noxious or pruritic stimuli. The superficial dorsal horn, which is the main target for nociceptive and pruritoceptive primary afferents, contains a high density of excitatory interneurons. Our understanding of their roles in somatosensory processing has been restricted by the difficulty of distinguishing functional populations among these cells. We recently defined 3 nonoverlapping populations among the excitatory neurons, based on the expression of neurotensin, neurokinin B, and gastrin-releasing peptide. Here we identify and characterise another population: neurons that express the tachykinin peptide substance P. We show with immunocytochemistry that its precursor protein (preprotachykinin A, PPTA) can be detected in ∼14% of lamina I-II neurons, and these are concentrated in the outer part of lamina II. Over 80% of the PPTA-positive cells lack the transcription factor Pax2 (which determines an inhibitory phenotype), and these account for ∼15% of the excitatory neurons in this region. They are different from the neurotensin, neurokinin B, or gastrin-releasing peptide neurons, although many of them contain somatostatin, which is widely expressed among superficial dorsal horn excitatory interneurons. We show that many of these cells respond to noxious thermal and mechanical stimuli and to intradermal injection of pruritogens. Finally, we demonstrate that these cells can also be identified in a knock-in Cre mouse line (Tac1Cre), although our findings suggest that there is an additional population of neurons that transiently express PPTA. This population of substance P–expressing excitatory neurons is likely to play an important role in the transmission of signals that are perceived as pain and itch.
Collapse
|
224
|
Wan L, Jin H, Liu XY, Jeffry J, Barry DM, Shen KF, Peng JH, Liu XT, Jin JH, Sun Y, Kim R, Meng QT, Mo P, Yin J, Tao A, Bardoni R, Chen ZF. Distinct roles of NMB and GRP in itch transmission. Sci Rep 2017; 7:15466. [PMID: 29133874 PMCID: PMC5684337 DOI: 10.1038/s41598-017-15756-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 11/01/2017] [Indexed: 01/12/2023] Open
Abstract
A key question in our understanding of itch coding mechanisms is whether itch is relayed by dedicated molecular and neuronal pathways. Previous studies suggested that gastrin-releasing peptide (GRP) is an itch-specific neurotransmitter. Neuromedin B (NMB) is a mammalian member of the bombesin family of peptides closely related to GRP, but its role in itch is unclear. Here, we show that itch deficits in mice lacking NMB or GRP are non-redundant and Nmb/Grp double KO (DKO) mice displayed additive deficits. Furthermore, both Nmb/Grp and Nmbr/Grpr DKO mice responded normally to a wide array of noxious stimuli. Ablation of NMBR neurons partially attenuated peripherally induced itch without compromising nociceptive processing. Importantly, electrophysiological studies suggested that GRPR neurons receive glutamatergic input from NMBR neurons. Thus, we propose that NMB and GRP may transmit discrete itch information and NMBR neurons are an integral part of neural circuits for itch in the spinal cord.
Collapse
Affiliation(s)
- Li Wan
- 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 Pain Medicine, The State Key Clinical Specialty in Pain Medicine, The Second Affiliated Hospital, Guangzhou Medical University, Guangdong, 510260, P.R. China
| | - Hua Jin
- 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 Anesthesiology, The First Hospital of Yunnan Province, Kunming, Yunnan, 650031, P.R. China
| | - 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
| | - 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
| | - 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
| | - Kai-Feng Shen
- 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 Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing, 400037, P.R. China
| | - 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
| | - Xue-Ting 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
- Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, The State Key Laboratory of Respiratory Disease, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, 510260, P.R. China
| | - Jin-Hua Jin
- 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 Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100144, P.R. China
| | - Yu Sun
- 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 Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, P.R. China
| | - Ray Kim
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - 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
- Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060, P.R. China
| | - Ping Mo
- 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 Anesthesiology, the Affiliated Nanhai Hospital of Southern Medical University, Foshan, Guangdong, 528000, P.R. China
| | - 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
| | - Ailin Tao
- Guangdong Provincial Key Laboratory of Allergy & Clinical Immunology, The State Key Laboratory of Respiratory Disease, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong, 510260, P.R. China
| | - Rita Bardoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, 41125, Italy
| | - 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.
| |
Collapse
|
225
|
Nguyen MQ, Wu Y, Bonilla LS, von Buchholtz LJ, Ryba NJP. Diversity amongst trigeminal neurons revealed by high throughput single cell sequencing. PLoS One 2017; 12:e0185543. [PMID: 28957441 PMCID: PMC5619795 DOI: 10.1371/journal.pone.0185543] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/14/2017] [Indexed: 12/17/2022] Open
Abstract
The trigeminal ganglion contains somatosensory neurons that detect a range of thermal, mechanical and chemical cues and innervate unique sensory compartments in the head and neck including the eyes, nose, mouth, meninges and vibrissae. We used single-cell sequencing and in situ hybridization to examine the cellular diversity of the trigeminal ganglion in mice, defining thirteen clusters of neurons. We show that clusters are well conserved in dorsal root ganglia suggesting they represent distinct functional classes of somatosensory neurons and not specialization associated with their sensory targets. Notably, functionally important genes (e.g. the mechanosensory channel Piezo2 and the capsaicin gated ion channel Trpv1) segregate into multiple clusters and often are expressed in subsets of cells within a cluster. Therefore, the 13 genetically-defined classes are likely to be physiologically heterogeneous rather than highly parallel (i.e., redundant) lines of sensory input. Our analysis harnesses the power of single-cell sequencing to provide a unique platform for in silico expression profiling that complements other approaches linking gene-expression with function and exposes unexpected diversity in the somatosensory system.
Collapse
Affiliation(s)
- Minh Q. Nguyen
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Youmei Wu
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lauren S. Bonilla
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lars J. von Buchholtz
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicholas J. P. Ryba
- Taste and Smell Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America
| |
Collapse
|
226
|
Abstract
The exteroceptive somatosensory system is important for reflexive and adaptive behaviors and for the dynamic control of movement in response to external stimuli. This review outlines recent efforts using genetic approaches in the mouse to map the spinal cord circuits that transmit and gate the cutaneous somatosensory modalities of touch, pain, and itch. Recent studies have revealed an underlying modular architecture in which nociceptive, pruritic, and innocuous stimuli are processed by distinct molecularly defined interneuron cell types. These include excitatory populations that transmit information about both innocuous and painful touch and inhibitory populations that serve as a gate to prevent innocuous stimuli from activating the nociceptive and pruritic transmission pathways. By dissecting the cellular composition of dorsal-horn networks, studies are beginning to elucidate the intricate computational logic of somatosensory transformation in health and disease.
Collapse
Affiliation(s)
- Stephanie C Koch
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| | - David Acton
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| | - Martyn Goulding
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
| |
Collapse
|
227
|
Itch induces conditioned place aversion in mice. Neurosci Lett 2017; 658:91-96. [DOI: 10.1016/j.neulet.2017.08.046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/16/2017] [Accepted: 08/17/2017] [Indexed: 11/23/2022]
|
228
|
Astrocytes in the spinal dorsal horn and chronic itch. Neurosci Res 2017; 126:9-14. [PMID: 28870604 DOI: 10.1016/j.neures.2017.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 08/16/2017] [Accepted: 08/17/2017] [Indexed: 11/22/2022]
Abstract
Chronic itch is a hallmark symptom of inflammatory skin conditions, such as atopic dermatitis. Existing treatment for chronic itch is largely ineffective. Despite recent progress in our understanding of the neuronal basis for itch sensation in the peripheral and central nervous systems, the mechanisms underlying how itch turns into a pathological chronic state remain poorly understood. Recent studies have uncovered the causal role of astrocytes in the spinal dorsal horn using mouse models of chronic itch, including atopic dermatitis. Understanding the key roles of astrocytes may provide us with exciting insights into the mechanisms for the chronicity of itch sensation and clues to develop novel therapeutic agents for treating chronic itch.
Collapse
|
229
|
Sun S, Xu Q, Guo C, Guan Y, Liu Q, Dong X. Leaky Gate Model: Intensity-Dependent Coding of Pain and Itch in the Spinal Cord. Neuron 2017; 93:840-853.e5. [PMID: 28231466 DOI: 10.1016/j.neuron.2017.01.012] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 12/06/2016] [Accepted: 01/13/2017] [Indexed: 01/01/2023]
Abstract
Coding of itch versus pain has been heatedly debated for decades. However, the current coding theories (labeled line, intensity, and selectivity theory) cannot accommodate all experimental observations. Here we identified a subset of spinal interneurons, labeled by gastrin-releasing peptide (Grp), that receive direct synaptic input from both pain and itch primary sensory neurons. When activated, these Grp+ neurons generated rarely seen, simultaneous robust pain and itch responses that were intensity dependent. Accordingly, we propose a "leaky gate" model in which Grp+ neurons transmit both itch and weak pain signals; however, upon strong painful stimuli, the recruitment of endogenous opioids works to close this gate, reducing overwhelming pain generated by parallel pathways. Consistent with our model, loss of these Grp+ neurons increased pain responses while itch was decreased. Our new model serves as an example of non-monotonic coding in the spinal cord and better explains observations in human psychophysical studies.
Collapse
Affiliation(s)
- Shuohao Sun
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qian Xu
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Changxiong Guo
- Department of Anesthesiology and the Center for the Study of Itch, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qin Liu
- Department of Anesthesiology and the Center for the Study of Itch, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| |
Collapse
|
230
|
Ramsden CE, Domenichiello AF, Yuan ZX, Sapio MR, Keyes GS, Mishra SK, Gross JR, Majchrzak-Hong S, Zamora D, Horowitz MS, Davis JM, Sorokin AV, Dey A, LaPaglia DM, Wheeler JJ, Vasko MR, Mehta NN, Mannes AJ, Iadarola MJ. A systems approach for discovering linoleic acid derivatives that potentially mediate pain and itch. Sci Signal 2017; 10:eaal5241. [PMID: 28831021 PMCID: PMC5805383 DOI: 10.1126/scisignal.aal5241] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chronic pain and itch are common hypersensitivity syndromes that are affected by endogenous mediators. We applied a systems-based, translational approach to predict, discover, and characterize mediators of pain and itch that are regulated by diet and inflammation. Profiling of tissue-specific precursor abundance and biosynthetic gene expression predicted that inflamed skin would be abundant in four previously unknown 11-hydroxy-epoxy- or 11-keto-epoxy-octadecenoate linoleic acid derivatives and four previously identified 9- or 13-hydroxy-epoxy- or 9- or 13-keto-epoxy-octadecenoate linoleic acid derivatives. All of these mediators were confirmed to be abundant in rat and human skin by mass spectrometry. However, only the two 11-hydroxy-epoxy-octadecenoates sensitized rat dorsal root ganglion neurons to release more calcitonin gene-related peptide (CGRP), which is involved in pain transmission, in response to low pH (which mimics an inflammatory state) or capsaicin (which activates ion channels involved in nociception). The two 11-hydroxy-epoxy-octadecenoates share a 3-hydroxy-Z-pentenyl-E-epoxide moiety, thus suggesting that this substructure could mediate nociceptor sensitization. In rats, intradermal hind paw injection of 11-hydroxy-12,13-trans-epoxy-(9Z)-octadecenoate elicited C-fiber-mediated sensitivity to thermal pain. In a randomized trial testing adjunctive strategies to manage refractory chronic headaches, reducing the dietary intake of linoleic acid was associated with decreases in plasma 11-hydroxy-12,13-trans-epoxy-(9Z)-octadecenoate, which correlated with clinical pain reduction. Human psoriatic skin had 30-fold higher 9-keto-12,13-trans-epoxy-(10E)-octadecenoate compared to control skin, and intradermal injection of this compound induced itch-related scratching behavior in mice. Collectively, these findings define a family of endogenous mediators with potential roles in pain and itch.
Collapse
Affiliation(s)
- Christopher E Ramsden
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA.
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20814, USA
- Department of Physical Medicine and Rehabilitation, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Anthony F Domenichiello
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Zhi-Xin Yuan
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
| | - Matthew R Sapio
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD 20814, USA
| | - Gregory S Keyes
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
| | - Santosh K Mishra
- Department of Molecular Biomedical Sciences, NC State College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Jacklyn R Gross
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD 20814, USA
| | - Sharon Majchrzak-Hong
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20814, USA
| | - Daisy Zamora
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516, USA
| | - Mark S Horowitz
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
| | - John M Davis
- Lipid Mediators, Inflammation, and Pain Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health (NIH), Bethesda, MD 21224, USA
- Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Alexander V Sorokin
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20814, USA
| | - Amit Dey
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20814, USA
| | - Danielle M LaPaglia
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD 20814, USA
| | - Joshua J Wheeler
- Department of Molecular Biomedical Sciences, NC State College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Michael R Vasko
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Nehal N Mehta
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20814, USA
| | - Andrew J Mannes
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD 20814, USA
| | - Michael J Iadarola
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD 20814, USA
| |
Collapse
|
231
|
Mu D, Deng J, Liu KF, Wu ZY, Shi YF, Guo WM, Mao QQ, Liu XJ, Li H, Sun YG. A central neural circuit for itch sensation. Science 2017; 357:695-699. [DOI: 10.1126/science.aaf4918] [Citation(s) in RCA: 131] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 07/07/2017] [Indexed: 12/17/2022]
|
232
|
Wong LS, Wu T, Lee CH. Inflammatory and Noninflammatory Itch: Implications in Pathophysiology-Directed Treatments. Int J Mol Sci 2017; 18:E1485. [PMID: 28698528 PMCID: PMC5535975 DOI: 10.3390/ijms18071485] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/01/2017] [Accepted: 07/05/2017] [Indexed: 12/13/2022] Open
Abstract
Itch is the main chief complaint in patients visiting dermatologic clinics and has the ability to deeply impair life quality. Itch results from activation of cutaneous nerve endings by noxious stimuli such as inflammatory mediators, neurotransmitters and neuropeptides, causing itch signal transduction from peripheral skin, through the spinal cord and thalamus, to the brain cortex. Primarily noninflammatory diseases, such as uremic pruritus, cause itch through certain pruritogens in the skin. In inflammatory skin diseases, atopic dermatitis (AD) is the prototypic disease causing intensive itch by aberrant skin inflammation and epidermal barrier disruption. Recent understanding of disease susceptibility, severity markers, and mechanisms have helped to develop targeted therapy for itch in AD, including monoclonal antibodies against IL-4, IL-13, thymic stromal lymphopoietin (TSLP), IgE and IL-31. Promising effects have been observed in some of them. In this review, we summarized targeted therapies for inflammatory itch in AD and for managing abnormal itch transductions in other common itching skin diseases.
Collapse
Affiliation(s)
- Lai-San Wong
- Department of Dermatology, College of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Kaohsiung 833, Taiwan.
| | - Tiffany Wu
- Zanvyl Kreiger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD 21287, USA.
| | - Chih-Hung Lee
- Department of Dermatology, College of Medicine, Chang Gung Memorial Hospital and Chang Gung University, Kaohsiung 833, Taiwan.
| |
Collapse
|
233
|
Huang C, Lu F, Li P, Cao C, Liu Z. Tlx3 Function in the Dorsal Root Ganglion is Pivotal to Itch and Pain Sensations. Front Mol Neurosci 2017; 10:205. [PMID: 28701920 PMCID: PMC5487456 DOI: 10.3389/fnmol.2017.00205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/12/2017] [Indexed: 12/12/2022] Open
Abstract
Itch, a sensation eliciting a desire to scratch, is distinct from but not completely independent of pain. Inspiring achievements have been made in the characterization of itch-related receptors and neurotransmitters, but the molecular mechanisms controlling the development of pruriceptors remain poorly understood. Here, our RNAseq and in situ hybridization data show that the transcription factor Tlx3 is required for the expression of a majority of itch-related molecules in the dorsal root ganglion (DRG). As a result, Tlx3F/F;Nav1.8-cre mice exhibit significantly attenuated acute and dry skin-induced chronic itch. Furthermore, our study indicates that TRPV1 plays a pivotal role in the chronic itch evoked by dry skin and allergic contact dermatitis (ACD). The mutants also display impaired response to cold and inflammatory pain and elevated response to capsaicin, whereas the responses to acute mechanical, thermal stimuli and neuropathic pain remain normal. In Tlx3F/F;Nav1.8-cre mice, TRPV1 is derepressed and expands predominantly into IB4+ non-peptidergic (NP) neurons. Collectively, our data reveal a molecular mechanism in regulating the development of pruriceptors and controlling itch and pain sensations.
Collapse
Affiliation(s)
| | - Fumin Lu
- School of Life Sciences, Anhui Agricultural UniversityHefei, China
| | - Ping Li
- Beijing Institute of BiotechnologyBeijing, China
| | - Cheng Cao
- Beijing Institute of BiotechnologyBeijing, China
| | - Zijing Liu
- Beijing Institute of BiotechnologyBeijing, China
| |
Collapse
|
234
|
Li C, Wang S, Chen Y, Zhang X. Somatosensory Neuron Typing with High-Coverage Single-Cell RNA Sequencing and Functional Analysis. Neurosci Bull 2017; 34:200-207. [PMID: 28612318 PMCID: PMC5799126 DOI: 10.1007/s12264-017-0147-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/04/2017] [Indexed: 12/27/2022] Open
Abstract
Different physical and chemical stimuli are detected by the peripheral sensory receptors of dorsal root ganglion (DRG) neurons, and the generated inputs are transmitted via afferent fibers into the central nervous system. The gene expression profiles of DRG neurons contribute to the generation, transmission, and regulation of various somatosensory signals. Recently, the single-cell transcriptomes, cell types, and functional annotations of somatosensory neurons have been studied. In this review, we introduce our classification of DRG neurons based on single-cell RNA-sequencing and functional analyses, and discuss the technical approaches. Moreover, studies on the molecular and cellular mechanisms underlying somatic sensations are discussed.
Collapse
Affiliation(s)
- Changlin Li
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Center for Excellence in Brain Science, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Sashuang Wang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Center for Excellence in Brain Science, Chinese Academy of Sciences, Shanghai, 200031, China.,School of Life Science and Technology, ShanghaiTec University, Shanghai, 200031, China
| | - Yan Chen
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Center for Excellence in Brain Science, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xu Zhang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Center for Excellence in Brain Science, Chinese Academy of Sciences, Shanghai, 200031, China. .,School of Life Science and Technology, ShanghaiTec University, Shanghai, 200031, China.
| |
Collapse
|
235
|
Green D, Dong X. The cell biology of acute itch. J Cell Biol 2017; 213:155-61. [PMID: 27114499 PMCID: PMC4862869 DOI: 10.1083/jcb.201603042] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 04/05/2016] [Indexed: 01/22/2023] Open
Abstract
Itch, the irritation we feel and the relief that comes from scratching, is an evolutionary warning system and defense against harmful environmental agents. Although once considered a subtype of pain, itch is now recognized as a unique sense, with its own distinct physiology and cell receptors. Here, we discuss recent advances in our understanding of itch and the molecular players that mediate this sensory modality.
Collapse
Affiliation(s)
- Dustin Green
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205 Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| |
Collapse
|
236
|
Duan B, Cheng L, Ma Q. Spinal Circuits Transmitting Mechanical Pain and Itch. Neurosci Bull 2017; 34:186-193. [PMID: 28484964 PMCID: PMC5799122 DOI: 10.1007/s12264-017-0136-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/01/2017] [Indexed: 12/11/2022] Open
Abstract
In 1905, Henry Head first suggested that transmission of pain-related protopathic information can be negatively modulated by inputs from afferents sensing innocuous touch and temperature. In 1965, Melzak and Wall proposed a more concrete gate control theory of pain that highlights the interaction between unmyelinated C fibers and myelinated A fibers in pain transmission. Here we review the current understanding of the spinal microcircuits transmitting and gating mechanical pain or itch. We also discuss how disruption of the gate control could cause pain or itch evoked by innocuous mechanical stimuli, a hallmark symptom for many chronic pain or itch patients.
Collapse
Affiliation(s)
- Bo Duan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Ave, Ann Arbor, MI, 48109, USA.
| | - Longzhen Cheng
- Institute of Brain Science, the State Key Laboratory of Medical Neurobiology and the Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China.
| | - Qiufu Ma
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, 1 Jimmy Fund Way, Boston, MA, 02115, USA.
| |
Collapse
|
237
|
Hierarchical Specification of Pruriceptors by Runt-Domain Transcription Factor Runx1. J Neurosci 2017; 37:5549-5561. [PMID: 28476948 DOI: 10.1523/jneurosci.0094-17.2017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/11/2017] [Accepted: 04/26/2017] [Indexed: 02/04/2023] Open
Abstract
The somatic sensory neurons in dorsal root ganglia (DRG) detect and transmit a diverse array of sensory modalities, such as pain, itch, cold, warm, touch, and others. Recent genetic and single-cell RNA sequencing studies have revealed a group of DRG neurons that could be particularly relevant for acute and chronic itch information transmission. They express the natriuretic peptide type B (NPPB), as well as a cohort of receptors and neuropeptides that have been implicated in chronic itch manifestation, including the interleukin-31 receptor A (IL-31ra) and its coreceptor oncostatin M receptor (Osmr), the cysteinyl leukotriene receptor 2 (Cysltr2), somatostatin, and neurotensin. However, how these neurons are generated during development remains unclear. Here we report that Runx1 is required to establish all these molecular features of NPPB+ neurons. We further show that while early embryonic Runx1 activity is required for the formation of NPPB+ cells, at later stages Runx1 switches to a genetic repressor and thus its downregulation becomes a prerequisite for the proper development of these pruriceptors. This mode by Runx1 is analogous to that in controlling another group of pruriceptors that specifically express the chloroquine receptor MrgprA3. Finally, behavioral studies using both sexes of mice revealed marked deficits in processing acute and chronic itch in Runx1 conditional knock-out mice, possibly attributable to impaired development of various pruriceptors.SIGNIFICANCE STATEMENT Our studies reveal a generalized control mode by Runx1 for pruriceptor development and consolidate a hierarchical control mechanism for the formation of sensory neurons transmitting distinct modalities. Among dorsal root ganglion neurons that initially express the neurotrophin receptor TrkA, Runx1 is necessary for the proper development of those neurons that innervate tissues derived from the ectoderm such as skin epidermis and hair follicles. These Runx1-dependent cutaneous sensory neurons are then divided into two groups based on persistent or transient Runx1 expression. The Runx1-persistent group is involved in transmitting mechanical and thermal information, whereas the Runx1-transient group transmits pruriceptive information. Such hierarchical control mechanisms may provide a developmental solution for the formation of sensory circuits that transmit distinct modalities.
Collapse
|
238
|
Spinal cord interneurons expressing the gastrin-releasing peptide receptor convey itch through VGLUT2-mediated signaling. Pain 2017; 158:945-961. [PMID: 28157737 PMCID: PMC5402714 DOI: 10.1097/j.pain.0000000000000861] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Supplemental Digital Content is Available in the Text. Gastrin-releasing peptide receptor–expressing cells are interneurons that use glutamate to transmit the perception of chemical itch to the next step in the labeled line of itch in the spinal cord. Itch is a sensation that promotes the desire to scratch, which can be evoked by mechanical and chemical stimuli. In the spinal cord, neurons expressing the gastrin-releasing peptide receptor (GRPR) have been identified as specific mediators of itch. However, our understanding of the GRPR population in the spinal cord, and thus how these neurons exercise their functions, is limited. For this purpose, we constructed a Cre line designed to target the GRPR population of neurons (Grpr-Cre). Our analysis revealed that Grpr-Cre cells in the spinal cord are predominantly excitatory interneurons that are found in the dorsal lamina, especially in laminae II-IV. Application of the specific agonist gastrin-releasing peptide induced spike responses in 43.3% of the patched Grpr-Cre neurons, where the majority of the cells displayed a tonic firing property. Additionally, our analysis showed that the Grpr-Cre population expresses Vglut2 mRNA, and mice ablated of Vglut2 in Grpr-Cre cells (Vglut2-lox;Grpr-Cre mice) displayed less spontaneous itch and attenuated responses to both histaminergic and nonhistaminergic agents. We could also show that application of the itch-inducing peptide, natriuretic polypeptide B, induces calcium influx in a subpopulation of Grpr-Cre neurons. To summarize, our data indicate that the Grpr-Cre spinal cord neural population is composed of interneurons that use VGLUT2-mediated signaling for transmitting chemical and spontaneous itch stimuli to the next, currently unknown, neurons in the labeled line of itch.
Collapse
|
239
|
Abstract
Itch is a protective sensation producing a desire to scratch. Pathologic itch can be a chronic symptom of illnesses such as uremia, cholestatic liver disease, neuropathies and dermatitis, however current therapeutic options are limited. Many types of cell surface receptors, including those present on cells in the skin, on sensory neurons and on neurons in the spinal cord, have been implicated in itch signaling. The role of G protein signaling in the regulation of pruriception is poorly understood. We identify here 2 G protein signaling components whose mutation impairs itch sensation. R7bp (a.k.a. Rgs7bp) is a palmitoylated membrane anchoring protein expressed in neurons that facilitates Gαi/o -directed GTPase activating protein activity mediated by the Gβ5/R7-RGS complex. Knockout of R7bp diminishes scratching responses to multiple cutaneously applied and intrathecally-administered pruritogens in mice. Knock-in to mice of a GTPase activating protein-insensitive mutant of Gαo (Gnao1 G184S/+) produces a similar pruriceptive phenotype. The pruriceptive defect in R7bp knockout mice was rescued in double knockout mice also lacking Oprk1, encoding the G protein-coupled kappa-opioid receptor whose activation is known to inhibit itch sensation. In a model of atopic dermatitis (eczema), R7bp knockout mice showed diminished scratching behavior and enhanced sensitivity to kappa opioid agonists. Taken together, our results indicate that R7bp is a key regulator of itch sensation and suggest the potential targeting of R7bp-dependent GTPase activating protein activity as a novel therapeutic strategy for pathological itch.
Collapse
|
240
|
Miao X, Huang Y, Liu TT, Guo R, Wang B, Wang XL, Chen LH, Zhou Y, Ji RR, Liu T. TNF-α/TNFR1 Signaling is Required for the Full Expression of Acute and Chronic Itch in Mice via Peripheral and Central Mechanisms. Neurosci Bull 2017; 34:42-53. [PMID: 28365861 DOI: 10.1007/s12264-017-0124-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 02/09/2017] [Indexed: 12/30/2022] Open
Abstract
Increasing evidence suggests that cytokines and chemokines play crucial roles in chronic itch. In the present study, we evaluated the roles of tumor necrosis factor-alpha (TNF-α) and its receptors TNF receptor subtype-1 (TNFR1) and TNFR2 in acute and chronic itch in mice. Compared to wild-type (WT) mice, TNFR1-knockout (TNFR1-KO) and TNFR1/R2 double-KO (DKO), but not TNFR2-KO mice, exhibited reduced acute itch induced by compound 48/80 and chloroquine (CQ). Application of the TNF-synthesis inhibitor thalidomide and the TNF-α antagonist etanercept dose-dependently suppressed acute itch. Intradermal injection of TNF-α was not sufficient to evoke scratching, but potentiated itch induced by compound 48/80, but not CQ. In addition, compound 48/80 induced TNF-α mRNA expression in the skin, while CQ induced its expression in the dorsal root ganglia (DRG) and spinal cord. Furthermore, chronic itch induced by dry skin was reduced by administration of thalidomide and etanercept and in TNFR1/R2 DKO mice. Dry skin induced TNF-α expression in the skin, DRG, and spinal cord and TNFR1 expression only in the spinal cord. Thus, our findings suggest that TNF-α/TNFR1 signaling is required for the full expression of acute and chronic itch via peripheral and central mechanisms, and targeting TNFR1 may be beneficial for chronic itch treatment.
Collapse
MESH Headings
- Animals
- Chloroquine/toxicity
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Etanercept/therapeutic use
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Pruritus/chemically induced
- Pruritus/drug therapy
- Pruritus/metabolism
- Pruritus/pathology
- RNA, Messenger/metabolism
- Receptors, Tumor Necrosis Factor, Type I/deficiency
- Receptors, Tumor Necrosis Factor, Type I/genetics
- Receptors, Tumor Necrosis Factor, Type II/deficiency
- Receptors, Tumor Necrosis Factor, Type II/genetics
- Signal Transduction/drug effects
- Skin/drug effects
- Skin/metabolism
- Spinal Cord/drug effects
- Spinal Cord/metabolism
- Thalidomide/therapeutic use
- Time Factors
- Tumor Necrosis Factor-alpha/adverse effects
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
- p-Methoxy-N-methylphenethylamine/toxicity
Collapse
Affiliation(s)
- Xiuhua Miao
- The Affiliated Zhangjiagang Hospital of Soochow University, Zhangjiagang, 215600, China
| | - Ya Huang
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China
| | - Teng-Teng Liu
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China
| | - Ran Guo
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China
| | - Bing Wang
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China
| | - Xue-Long Wang
- Capital Medical University Electric Power Teaching Hospital, Beijing, 100073, China
| | - Li-Hua Chen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, 215123, China
| | - Yan Zhou
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China
| | - Ru-Rong Ji
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, 27710, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Tong Liu
- The Affiliated Zhangjiagang Hospital of Soochow University, Zhangjiagang, 215600, China.
- Institute of Neuroscience, Soochow University, Suzhou, 215021, China.
| |
Collapse
|
241
|
Abstract
Peripheral itch stimuli are transmitted by sensory neurons to the spinal cord dorsal horn, which then transmits the information to the brain. The molecular and cellular mechanisms within the dorsal horn for itch transmission have only been investigated and identified during the past ten years. This review covers the progress that has been made in identifying the peptide families in sensory neurons and the receptor families in dorsal horn neurons as putative itch transmitters, with a focus on gastrin-releasing peptide (GRP)-GRP receptor signaling. Also discussed are the signaling mechanisms, including opioids, by which various types of itch are transmitted and modulated, as well as the many conflicting results arising from recent studies.
Collapse
|
242
|
Liu T, He Z, Tian X, Kamal GM, Li Z, Liu Z, Liu H, Xu F, Wang J, Xiang H. Specific patterns of spinal metabolites underlying α-Me-5-HT-evoked pruritus compared with histamine and capsaicin assessed by proton nuclear magnetic resonance spectroscopy. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1222-1230. [PMID: 28344131 DOI: 10.1016/j.bbadis.2017.03.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 03/22/2017] [Accepted: 03/22/2017] [Indexed: 12/29/2022]
Abstract
The mechanism behind itching is not well understood. Proton nuclear magnetic resonance (1H-NMR) spectroscopic analysis of spinal cord extracts provides a quick modality for evaluating the specific metabolic activity of α-Me-5-HT-evoked pruritus mice. In the current study, four groups of young adult male C57Bl/6 mice were investigated; one group treated with saline, while the other groups intradermally injected with α-Me-5-HT (histamine independent pruritogen), histamine (histamine dependent pruritogen) and capsaicin (algogenic substance), respectively. The intradermal microinjection of α-Me-5-HT and histamine resulted in a dramatic increase in the itch behavior. Furthermore, the results of NMR studies of the spinal cord extracts revealed that the metabolites show very different patterns for these different drugs, especially when comparing α-Me-5-HT and capsaicin. All the animals in the groups of α-Me-5-HT and capsaicin were completely separated using the metabolite parameters and principal component analysis. For α-Me-5-HT, the concentrations of glutamate, GABA, glycine and aspartate increased significantly, especially for GABA (increased 17.2%, p=0.008). Furthermore, the concentration of NAA increased, but there was no significant difference (increased 11.3%, p=0.191) compared to capsaicin (decreased 29.1%, p=0.002). Thus the application of magnetic resonance spectroscopy technique, coupled with statistical analysis, could further explain the mechanism behind itching evoked by α-Me-5-HT or other drugs. It can thus improve our understanding of itch pathophysiology and pharmacological therapies which may contribute to itch relief.
Collapse
Affiliation(s)
- Taotao Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China; Department of Anesthesiology, Peking University Third Hospital, Beijing 100191, China
| | - Zhigang He
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Xuebi Tian
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Ghulam Mustafa Kamal
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Zhixiao Li
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China
| | - Zeyuan Liu
- College of Life Science, Wuhan University, Wuhan, Hubei 430076, PR China
| | - Huili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China
| | - Fuqiang Xu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Jie Wang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
| | - Hongbing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, PR China.
| |
Collapse
|
243
|
Synergistic antipruritic effects of gamma aminobutyric acid A and B agonists in a mouse model of atopic dermatitis. J Allergy Clin Immunol 2017; 140:454-464.e2. [PMID: 28232084 DOI: 10.1016/j.jaci.2017.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 01/25/2017] [Accepted: 02/01/2017] [Indexed: 11/21/2022]
Abstract
BACKGROUND Despite recent insights into the pathophysiology of acute and chronic itch, chronic itch remains an often intractable condition. Among major contributors to chronic itch is dysfunction of spinal cord gamma aminobutyric acidergic (GABAergic) inhibitory controls. OBJECTIVES We sought to test the hypothesis that selective GABA agonists as well as cell transplant-derived GABA are antipruritic against acute itch and in a transgenic mouse model of atopic dermatitis produced by overexpression of the TH2 cell-associated cytokine, IL-31 (IL-31Tg mice). METHODS We injected wild-type and IL-31Tg mice with combinations of GABA-A (muscimol) or GABA-B (baclofen) receptor agonists 15 to 20 minutes prior to injection of various pruritogens (histamine, chloroquine, or endothelin-1) and recorded spontaneous scratching before and after drug administration. We also tested the antipruritic properties of intraspinal transplantation of precursors of GABAergic interneurons in the IL-31Tg mice. RESULTS Systemic muscimol or baclofen are antipruritic against both histamine-dependent and -independent pruritogens, but the therapeutic window using either ligand alone was very small. In contrast, combined subthreshold doses of baclofen and muscimol produced a significant synergistic antipruritic effect, with no sedation. Finally, transplant-mediated long-term enhancement of GABAergic signaling not only reduced spontaneous scratching in the IL-31Tg mice but also dramatically resolved the associated skin lesions. CONCLUSIONS Although additional research is clearly needed, existing approved GABA agonists should be considered in the management of chronic itch, notably atopic dermatitis.
Collapse
|
244
|
|
245
|
Lee JS, Han JS, Lee K, Bang J, Lee H. The peripheral and central mechanisms underlying itch. BMB Rep 2017; 49:474-87. [PMID: 27418284 PMCID: PMC5227140 DOI: 10.5483/bmbrep.2016.49.9.108] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Indexed: 12/20/2022] Open
Abstract
Itch is one of the most distressing sensations that substantially impair quality of life. It is a cardinal symptom of many skin diseases and is also caused by a variety of systemic disorders. Unfortunately, currently available itch medications are ineffective in many chronic itch conditions, and they often cause undesirable side effects. To develop novel therapeutic strategies, it is essential to identify primary afferent neurons that selectively respond to itch mediators as well as the central nervous system components that process the sensation of itch and initiate behavioral responses. This review summarizes recent progress in the study of itch, focusing on itch-selective receptors, signaling molecules, neuronal pathways from the primary sensory neurons to the brain, and potential decoding mechanisms based on which itch is distinguished from pain. [BMB Reports 2016; 49(9): 474-487]
Collapse
Affiliation(s)
- Jae Seung Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| | | | - Kyeongho Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| | - Juwon Bang
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| | - Hyosang Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| |
Collapse
|
246
|
Toll-like receptor 4 contributes to chronic itch, alloknesis, and spinal astrocyte activation in male mice. Pain 2017; 157:806-817. [PMID: 26645545 DOI: 10.1097/j.pain.0000000000000439] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Increasing evidence suggests that Toll-like receptor 4 (TLR4) contributes importantly to spinal cord glial activation and chronic pain sensitization; however, its unique role in acute and chronic itch is unclear. In this study, we investigated the involvement of TLR4 in acute and chronic itch models in male mice using both transgenic and pharmacological approaches. Tlr4 mice exhibited normal acute itch induced by compound 48/80 and chloroquine, but these mice showed substantial reductions in scratching in chronic itch models of dry skin, induced by acetone and diethylether followed by water (AEW), contact dermatitis, and allergic contact dermatitis on the neck. Intrathecal (spinal) inhibition of TLR4 with lipopolysaccharide Rhodobacter sphaeroides did not affect acute itch but suppressed AEW-induced chronic itch. Compound 48/80 and AEW also produced robust alloknesis, a touch-elicited itch in wild-type mice, which was suppressed by intrathecal lipopolysaccharide R sphaeroides and Tlr4 deletion. Acetone and diethylether followed by water induced persistent upregulation of Tlr4 mRNA and increased TLR4 expression in GFAP-expressing astrocytes in spinal cord dorsal horn. Acetone and diethylether followed by water also induced TLR4-dependent astrogliosis (GFAP upregulation) in spinal cord. Intrathecal injection of astroglial inhibitor L-α-aminoadipate reduced AEW-induced chronic itch and alloknesis without affecting acute itch. Spinal TLR4 was also necessary for AEW-induced chronic itch in the cheek model. Interestingly, scratching plays an essential role in spinal astrogliosis because AEW-induced astrogliosis was abrogated by putting Elizabethan collars on the neck to prevent scratching the itchy skin. Our findings suggest that spinal TLR4 signaling is important for spinal astrocyte activation and astrogliosis that may underlie alloknesis and chronic itch.
Collapse
|
247
|
The molecular and cellular mechanisms of itch and the involvement of TRP channels in the peripheral sensory nervous system and skin. Allergol Int 2017; 66:22-30. [PMID: 28012781 DOI: 10.1016/j.alit.2016.10.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 12/24/2022] Open
Abstract
Itch is an unpleasant cutaneous sensation that can arise following insect bites, exposure to plant ingredients, and some diseases. Itch can also have idiopathic causes. Itch sensations are thought to protect against external insults and toxic substances. Although itch is not directly lethal, chronic and long lasting itch in certain diseases can worsen quality of life. Therefore, the mechanisms responsible for chronic itch require careful investigation. There is a significant amount of basic research concerning itch, and the effect of various itch mediators on primary sensory neurons have been studied. Interestingly, many mediators of itch involve signaling related to transient receptor potential (TRP) channels. TRP channels, especially thermosensitive TRP channels, are expressed by primary sensory neurons and skin keratinocytes, which receive multimodal stimuli, including those that cause itch sensations. Here we review the molecular and cellular mechanisms of itch and the involvement of TRP channels in mediating itch sensations.
Collapse
|
248
|
Akiyama T, Nagamine M, Davoodi A, Ivanov M, Carstens MI, Carstens E. Innocuous warming enhances peripheral serotonergic itch signaling and evokes enhanced responses in serotonin-responsive dorsal horn neurons in the mouse. J Neurophysiol 2017; 117:251-259. [PMID: 27784810 PMCID: PMC5220113 DOI: 10.1152/jn.00703.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/19/2016] [Indexed: 11/22/2022] Open
Abstract
Itch is often triggered by warming the skin in patients with itchy dermatitis, but the underlying mechanism is largely unknown. We presently investigated if warming the skin enhances histamine- or serotonin (5-HT)-evoked itch behavior or responses of sensory dorsal root ganglion (DRG) cells, and if responses of superficial dorsal horn neurons to innocuous warming are enhanced by these pruritogens. In a temperature-controlled environmental chamber, mice exhibited greater scratching following intradermal injection of 5-HT, but not histamine, SLIGRL, or BAM8-22, when the skin surface temperature was above 36°C. Calcium imaging of DRG cells in a temperature-controlled bath revealed that responses to 5-HT, but not histamine, were significantly greater at a bath temperature of 35°C vs. lower temperatures. Single-unit recordings revealed a subpopulation of superficial dorsal horn neurons responsive to intradermal injection of 5-HT. Of these, 58% responded to innocuous skin warming (37°C) prior to intradermal injection of 5-HT, while 100% responded to warming following intradermal injection of 5-HT. Warming-evoked responses were superimposed on the 5-HT-evoked elevation in firing and were significantly larger compared with responses pre-5-HT, as long as 30 min after the intradermal injection of 5-HT. Five-HT-insensitive units, and units that either did or did not respond to intradermal histamine, did not exhibit any increase in the incidence of warmth sensitivity or in the mean response to warming following intradermal injection of the pruritogen. The results suggest that 5-HT-evoked responses of pruriceptors are enhanced during skin warming, leading to increased firing of 5-HT-sensitive dorsal horn neurons that signal nonhistaminergic itch. NEW & NOTEWORTHY Skin warming often exacerbates itch in patients with itchy dermatitis. We demonstrate that warming the skin enhanced serotonin-evoked, but not histamine-evoked, itch behavior and responses of sensory dorsal root ganglion cells. Moreover, serotonin, but not histamine, enhanced responses of superficial dorsal horn neurons to innocuous warming. The results suggest that skin warming selectively enhances the responses of serotonin-sensitive pruriceptors, leading to increased firing of serotonin-sensitive dorsal horn neurons that signal nonhistaminergic itch.
Collapse
Affiliation(s)
- T Akiyama
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
- Departments of Dermatology, Anatomy, and Cell Biology, Temple Itch Center, Temple University, Philadelphia, Pennsylvania
| | - M Nagamine
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
| | - A Davoodi
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
| | - M Ivanov
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
| | - M Iodi Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
| | - E Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California; and
| |
Collapse
|
249
|
Furue M, Kadono T. New therapies for controlling atopic itch. J Dermatol 2016; 42:847-50. [PMID: 26332459 DOI: 10.1111/1346-8138.13060] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 12/17/2022]
Abstract
Chronic itch in atopic dermatitis markedly diminishes the quality of life of affected individuals. Sleep disturbance and impaired productivity in work due to chronic itch impose a socioeconomic burden. Conventional therapies for atopic dermatitis are capable of reducing atopic itch. However, the majority of patients are not satisfied with the antipruritic capacity of conventional treatments. In this review, we summarize recent progress in itch signaling in the skin, dorsal root ganglion and spinal cord. New therapies for controlling atopic itch are also discussed.
Collapse
Affiliation(s)
- Masutaka Furue
- Department of Dermatology, Kyushu University, Fukuoka, Japan
| | - Takafumi Kadono
- Department of Dermatology, St Marianna University School of Medicine, Kawasaki, Japan
| |
Collapse
|
250
|
Tian B, Wang XL, Huang Y, Chen LH, Cheng RX, Zhou FM, Guo R, Li JC, Liu T. Peripheral and spinal 5-HT receptors participate in cholestatic itch and antinociception induced by bile duct ligation in rats. Sci Rep 2016; 6:36286. [PMID: 27824106 PMCID: PMC5099756 DOI: 10.1038/srep36286] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022] Open
Abstract
Although 5-HT has been implicated in cholestatic itch and antinociception, two common phenomena in patients with cholestatic disease, the roles of 5-HT receptor subtypes are unclear. Herein, we investigated the roles of 5-HT receptors in itch and antinociception associated with cholestasis, which was induced by common bile duct ligation (BDL) in rats. 5-HT-induced enhanced scratching and antinociception to mechanical and heat stimuli were demonstrated in BDL rats. 5-HT level in the skin and spinal cord was significantly increased in BDL rats. Quantitative RT-PCR analysis showed 5-HT1B, 5-HT1D, 5-HT2A, 5-HT3A, 5-HT5B, 5-HT6, and 5-HT7 were up-regulated in peripheral nervous system and 5-HT1A, 5-HT1F, 5-HT2B, and 5-HT3A were down-regulated in the spinal cord of BDL rats. Intradermal 5-HT2, 5-HT3, and 5-HT7 receptor agonists induced scratching in BDL rats, whereas 5-HT3 agonist did not induce scratching in sham rats. 5-HT1A, 5-HT2, 5-HT3, and 5-HT7 agonists or antagonists suppressed itch in BDL rats. 5-HT1A agonist attenuated, but 5-HT1A antagonist enhanced antinociception in BDL rats. 5-HT2 and 5-HT3 agonists or antagonists attenuated antinociception in BDL rats. Our data suggested peripheral and central 5-HT system dynamically participated in itch and antinociception under cholestasis condition and targeting 5-HT receptors may be an effective treatment for cholestatic itch.
Collapse
Affiliation(s)
- Bin Tian
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Xue-Long Wang
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Ya Huang
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Li-Hua Chen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, School of Public Health, Soochow University, Suzhou, 215123, China
| | - Ruo-Xiao Cheng
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Feng-Ming Zhou
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Ran Guo
- Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Jun-Cheng Li
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Tong Liu
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| |
Collapse
|