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Pavlenko D, Todurga-Seven ZG, Sanders K, Markan A, Verpile R, Ishida H, Costo D, Akiyama T. Activation of NPY2R-expressing amygdala neurons inhibits itch behavior in mice without lateralization. Sci Rep 2024; 14:22125. [PMID: 39333236 PMCID: PMC11437048 DOI: 10.1038/s41598-024-73483-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 09/17/2024] [Indexed: 09/29/2024] Open
Abstract
The central amygdala (CeA) is a crucial hub in the processing of affective itch, containing a diverse array of neuronal populations. Among these components, Neuropeptide Y (NPY) and its receptors, such as NPY2R, affect various physiological and psychological processes. Despite this broad impact, the precise role of NPY2R+ CeA neurons in itch modulation remains unknown, particularly concerning any potential lateralization effects. To address this, we employed optogenetics to selectively stimulate NPY2R+ CeA neurons in mice, investigating their impact on itch modulation. Optogenetic activation of NPY2R+ CeA neurons reduced scratching behavior elicited by pruritogens without exhibiting any lateralization effects. Electrophysiological recordings confirmed increased neuronal activity upon stimulation. However, this modulation did not affect thermal sensitivity, mechanical sensitivity, or formalin-induced hyperalgesia. Additionally, no alterations in anxiety-like behaviors or locomotion were observed upon stimulation. Projection tracing revealed connections of NPY2R+ CeA neurons to brain regions implicated in itch processing. Overall, this comprehensive study highlights the role of NPY2R+ CeA neurons in itch regulation without any lateralization effects.
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Affiliation(s)
- Darya Pavlenko
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Zeynep Gizem Todurga-Seven
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
- Department of Medical Pharmacology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Kristen Sanders
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Anika Markan
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Rebecca Verpile
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Hirotake Ishida
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Dylan Costo
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA
| | - Tasuku Akiyama
- Dr. Phillip Frost Department of Dermatology & Cutaneous Surgery and Miami Itch Center, University of Miami Miller School of Medicine, 1600 NW 10th Ave., RMSB 2063, Miami, FL, 33136, USA.
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Villalón Landeros E, Kho SC, Church TR, Brennan A, Türker F, Delannoy M, Caterina MJ, Margolis SS. The nociceptive activity of peripheral sensory neurons is modulated by the neuronal membrane proteasome. Cell Rep 2024; 43:114058. [PMID: 38614084 PMCID: PMC11157458 DOI: 10.1016/j.celrep.2024.114058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/05/2024] [Accepted: 03/20/2024] [Indexed: 04/15/2024] Open
Abstract
Proteasomes are critical for peripheral nervous system (PNS) function. Here, we investigate mammalian PNS proteasomes and reveal the presence of the neuronal membrane proteasome (NMP). We show that specific inhibition of the NMP on distal nerve fibers innervating the mouse hind paw leads to reduction in mechanical and pain sensitivity. Through investigating PNS NMPs, we demonstrate their presence on the somata and proximal and distal axons of a subset of dorsal root ganglion (DRG) neurons. Single-cell RNA sequencing experiments reveal that the NMP-expressing DRGs are primarily MrgprA3+ and Cysltr2+. NMP inhibition in DRG cultures leads to cell-autonomous and non-cell-autonomous changes in Ca2+ signaling induced by KCl depolarization, αβ-meATP, or the pruritogen histamine. Taken together, these data support a model whereby NMPs are expressed on a subset of somatosensory DRGs to modulate signaling between neurons of distinct sensory modalities and indicate the NMP as a potential target for controlling pain.
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Affiliation(s)
- Eric Villalón Landeros
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Samuel C Kho
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Taylor R Church
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anna Brennan
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Fulya Türker
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael Delannoy
- Microscopy Facility, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael J Caterina
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurosurgery and Neurosurgery Pain Research Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seth S Margolis
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Li DJ, Zhong ZJ, Wang XL, Wei N, Zhao SJ, Shan TT, Liu YP, Yu YQ. Chemokine receptor CXCR2 in primary sensory neurons of trigeminal ganglion mediates orofacial itch. Front Mol Neurosci 2023; 16:1279237. [PMID: 37953876 PMCID: PMC10637378 DOI: 10.3389/fnmol.2023.1279237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/16/2023] [Indexed: 11/14/2023] Open
Abstract
The CXCR2 chemokine receptor is known to have a significant impact on the initiation and control of inflammatory processes. However, its specific involvement in the sensation of itch is not yet fully understood. In this study, we aimed to elucidate the function of CXCR2 in the trigeminal ganglion (TG) by utilizing orofacial itch models induced by incision, chloroquine (CQ), and histamine. Our results revealed a significant up-regulation of CXCR2 mRNA and protein expressions in the primary sensory neurons of TG in response to itch stimuli. The CXCR2 inhibitor SB225002 resulted in notable decrease in CXCR2 protein expression and reduction in scratch behaviors. Distal infraorbital nerve (DION) microinjection of a specific shRNA virus inhibited CXCR2 expression in TG neurons and reversed itch behaviors. Additionally, the administration of the PI3K inhibitor LY294002 resulted in a decrease in the expressions of p-Akt, Akt, and CXCR2 in TG neurons, thereby mitigating pruritic behaviors. Collectively, we report that CXCR2 in the primary sensory neurons of trigeminal ganglion contributes to orofacial itch through the PI3K/Akt signaling pathway. These observations highlight the potential of molecules involved in the regulation of CXCR2 as viable therapeutic targets for the treatment of itch.
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Affiliation(s)
- Dong-Jin Li
- College of Life Sciences, Northwest University, Xi’an, China
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Zhen-Juan Zhong
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Xiao-Liang Wang
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Na Wei
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Si-Jia Zhao
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Ting-Ting Shan
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Ya-Ping Liu
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
| | - Yao-Qing Yu
- College of Life Sciences, Northwest University, Xi’an, China
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Air Force Medical University, Xi’an, China
- Key Laboratory of Brain Stress and Behavior, People’s Liberation Army, Xi’an, China
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He W, Liang L, Zhang Y. Pungency Perception and the Interaction with Basic Taste Sensations: An Overview. Foods 2023; 12:2317. [PMID: 37372528 DOI: 10.3390/foods12122317] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 05/17/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023] Open
Abstract
The perception of pungency can be attributed to the combination of pain and heat, and it has critical impacts on food flavor and food consumption preferences. Many studies have reported a variety of pungent ingredients with different Scoville heat units (SHU), and the mechanism of pungent perception was revealed in vivo and in vitro. The worldwide use of spices containing pungent ingredients has led to an increasing awareness of their effects on basic tastes. However, the interaction between basic tastes and pungency perception based on structure-activity relationship, taste perception mechanism and neurotransmission lacks review and summary, considering its brighter prospects in food flavor. Thus, in this review, common pungency substances and pungency evaluation methods, and the mechanism of pungency perception is presented, and the interaction between basic tastes and pungency perception and the possible factors of their interaction are reviewed in detail. Pungent stimuli are mainly transduced through transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential fixed hormone isoform (TRPA1) activated by stimulants. Using modern detection techniques combined with sensory standards, different substances produce different degrees of pungent stimulation, ranging from 104 to 107 SHU/g. Pungent stimuli can affect taste receptor or channel protein conformation and regulate taste bud cell sensitivity by producing neurotransmission products. The products of neurotransmission and taste receptor cell activation in turn act on taste perception. When there are simultaneous effects of taste perception, pungency stimulation may enhance the perception of salty at a certain concentration, with a mutual inhibition effect with sour, sweet, and bitter taste, while its interaction with umami taste is not obvious. However, due to the complexity of perception and the uncertainty of many perceptual receptors or channels, the current studies of interactions are still controversial. Based on the understanding of the mechanism and influencing factors, the availability of pungency substances is proposed in the perspective of food industry in order to achieve new development.
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Affiliation(s)
- Wei He
- Food Laboratory of Zhongyuan, Beijing Technology and Business University, Beijing 100048, China
- Key Laboratory of Flavor Science of China General Chamber of Commerce, Beijing Technology and Business University, Beijing 100048, China
| | - Li Liang
- Food Laboratory of Zhongyuan, Beijing Technology and Business University, Beijing 100048, China
- Key Laboratory of Flavor Science of China General Chamber of Commerce, Beijing Technology and Business University, Beijing 100048, China
| | - Yuyu Zhang
- Food Laboratory of Zhongyuan, Beijing Technology and Business University, Beijing 100048, China
- Key Laboratory of Flavor Science of China General Chamber of Commerce, Beijing Technology and Business University, Beijing 100048, China
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Wheeler JJ, Domenichiello AF, Jensen JR, Keyes GS, Maiden KM, Davis JM, Ramsden CE, Mishra SK. Endogenous Derivatives of Linoleic Acid and their Stable Analogs Are Potential Pain Mediators. JID INNOVATIONS 2023; 3:100177. [PMID: 36876220 PMCID: PMC9982331 DOI: 10.1016/j.xjidi.2022.100177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 10/11/2022] [Accepted: 10/19/2022] [Indexed: 12/27/2022] Open
Abstract
Psoriasis is characterized by intense pruritus, with a subset of individuals with psoriasis experiencing thermal hypersensitivity. However, the pathophysiology of thermal hypersensitivity in psoriasis and other skin conditions remains enigmatic. Linoleic acid is an omega-6 fatty acid that is concentrated in the skin, and oxidation of linoleic acid into metabolites with multiple hydroxyl and epoxide functional groups has been shown to play a role in skin barrier function. Previously, we identified several linoleic acid‒derived mediators that were more concentrated in psoriatic lesions, but the role of these lipids in psoriasis remains unknown. In this study, we report that two such compounds-9,10-epoxy-13-hydroxy-octadecenoate and 9,10,13-trihydroxy-octadecenoate-are present as free fatty acids and induce nociceptive behavior in mice but not in rats. By chemically stabilizing 9,10-epoxy-13-hydroxy-octadecenoate and 9,10,13-trihydroxy-octadecenoate through the addition of methyl groups, we observed pain and hypersensitization in mice. The nociceptive responses suggest an involvement of the TRPA1 channel, whereas hypersensitive responses induced by these mediators may require both TRPA1 and TRPV1 channels. Furthermore, we showed that 9,10,13-trihydroxy-octadecenoate‒induced calcium transients in sensory neurons are mediated through the Gβγ subunit of an unidentified G-protein coupled receptor (GPCR). Overall, mechanistic insights from this study will guide the development of potential therapeutic targets for the treatment of pain and hypersensitivity.
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Key Words
- 9,10,13-THL, 9,10,13-trihydroxy-octadecenoate
- 9,13-EHL, 13-hydroxy-9,10-epoxy octadecenoate
- CFA, complete Freund’s adjuvant
- DRG, dorsal root ganglia
- GPCR, G-protein coupled receptor
- HODE, hydroxyoctadecenoate
- KO, knockout
- LA, linoleic acid
- LC-MS/MS, liquid chromatography‒tandem mass spectrometry
- PGE2, prostaglandin E2
- TRP, transient receptor potential
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Affiliation(s)
- Joshua J. Wheeler
- Department of Biomedical Sciences, College of Veterinary Medicine, NC State University, Raleigh, North Carolina, USA
- Comparative Medicine Institute, NC State University, Raleigh, North Carolina, USA
| | - Anthony F. Domenichiello
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore, Maryland, USA
| | - Jennifer R. Jensen
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore, Maryland, USA
- Neurosciences Graduate Program, University of California San Diego, La Jolla, California, USA
| | - Gregory S. Keyes
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore, Maryland, USA
| | - Kristen M. Maiden
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore, Maryland, USA
- Obstetrics-Gynecology Program, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - John M. Davis
- Department of Psychiatry, Psychiatry College of Medicine, University of Illinois at Chicago, Chicago, Ilinois, USA
| | - Christopher E. Ramsden
- Lipid Peroxidation Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
- Intramural Program of the National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Baltimore, Maryland, USA
| | - Santosh K. Mishra
- Department of Biomedical Sciences, College of Veterinary Medicine, NC State University, Raleigh, North Carolina, USA
- Comparative Medicine Institute, NC State University, Raleigh, North Carolina, USA
- Correspondence: Santosh K. Mishra, Department of Biomedical Sciences, College of Veterinary Medicine, NC State University, 1060 William Moore Drive, RB 242, Raleigh 27607, North Carolina, USA.
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Mießner H, Seidel J, Smith ESJ. In vitro models for investigating itch. Front Mol Neurosci 2022; 15:984126. [PMID: 36385768 PMCID: PMC9644192 DOI: 10.3389/fnmol.2022.984126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 10/10/2022] [Indexed: 12/04/2022] Open
Abstract
Itch (pruritus) is a sensation that drives a desire to scratch, a behavior observed in many animals. Although generally short-lasting and not causing harm, there are several pathological conditions where chronic itch is a hallmark symptom and in which prolonged scratching can induce damage. Finding medications to counteract the sensation of chronic itch has proven difficult due to the molecular complexity that involves a multitude of triggers, receptors and signaling pathways between skin, immune and nerve cells. While much has been learned about pruritus from in vivo animal models, they have limitations that corroborate the necessity for a transition to more human disease-like models. Also, reducing animal use should be encouraged in research. However, conducting human in vivo experiments can also be ethically challenging. Thus, there is a clear need for surrogate models to be used in pre-clinical investigation of the mechanisms of itch. Most in vitro models used for itch research focus on the use of known pruritogens. For this, sensory neurons and different types of skin and/or immune cells are stimulated in 2D or 3D co-culture, and factors such as neurotransmitter or cytokine release can be measured. There are however limitations of such simplistic in vitro models. For example, not all naturally occurring cell types are present and there is also no connection to the itch-sensing organ, the central nervous system (CNS). Nevertheless, in vitro models offer a chance to investigate otherwise inaccessible specific cell–cell interactions and molecular pathways. In recent years, stem cell-based approaches and human primary cells have emerged as viable alternatives to standard cell lines or animal tissue. As in vitro models have increased in their complexity, further opportunities for more elaborated means of investigating itch have been developed. In this review, we introduce the latest concepts of itch and discuss the advantages and limitations of current in vitro models, which provide valuable contributions to pruritus research and might help to meet the unmet clinical need for more refined anti-pruritic substances.
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Affiliation(s)
- Hendrik Mießner
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- Dermatological Skin Care, Beiersdorf AG, Hamburg, Germany
| | - Judith Seidel
- Dermatological Skin Care, Beiersdorf AG, Hamburg, Germany
| | - Ewan St. John Smith
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Ewan St. John Smith,
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Katayama Y, Miura A, Sakamoto T, Takanami K, Sakamoto H. Footedness for scratching itchy eyes in rodents. Proc Biol Sci 2022; 289:20221126. [PMID: 36259204 PMCID: PMC9579771 DOI: 10.1098/rspb.2022.1126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 09/21/2022] [Indexed: 11/12/2022] Open
Abstract
The neural bases of itchy eye transmission remain unclear compared with those involved in body itch. Here, we show in rodents that the gastrin-releasing peptide receptor (GRPR) of the trigeminal sensory system is involved in the transmission of itchy eyes. Interestingly, we further demonstrate a difference in scratching behaviour between the left and right hindfeet in rodents; histamine instillation into the conjunctival sac of both eyes revealed right-foot biased laterality in the scratching movements. Unilateral histamine instillation specifically induced neural activation in the ipsilateral sensory pathway, with no significant difference between the activations following left- and right-eye instillations. Thus, the behavioural laterality is presumably due to right-foot preference in rodents. Genetically modified rats with specific depletion of Grpr-expressing neurons in the trigeminal sensory nucleus caudalis of the medulla oblongata exhibited fewer and shorter histamine-induced scratching movements than controls and eliminated the footedness. These results taken together indicate that the Grpr-expressing neurons are required for the transmission of itch sensation from the eyes, but that foot preference is generated centrally. These findings could open up a new field of research on the mechanisms of the laterality in vertebrates and also offer new potential therapeutic approaches to refractory pruritic eye disorders.
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Affiliation(s)
- Yukitoshi Katayama
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
| | - Ayane Miura
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
- Department of Biology, Faculty of Science, Okayama University, 3-1-1 Kita-ku, Tsushimanaka, Okayama 700-8530, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
| | - Keiko Takanami
- Mouse Genomics Resources Laboratory, National Institute of Genetics, Yata, Mishima, Shizuoka 411-8540, Japan
- Department of Environmental Health, Faculty of Human Life and Environmental Sciences, Nara Women's University, Kitauoya Nishimachi, Nara 630-8506, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
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Zhang Y, Richter N, König C, Kremer AE, Zimmermann K. Generalized resistance to pruritogen-induced scratching in the C3H/HeJ strain. Front Mol Neurosci 2022; 15:934564. [PMID: 36277491 PMCID: PMC9581333 DOI: 10.3389/fnmol.2022.934564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/22/2022] [Indexed: 11/18/2022] Open
Abstract
Previously the effect of the pruritogens, such as histamine and chloroquine, was tested in 11 inbred mouse strains, and this study aimed to identify resistant and sensitive strains, consistent with the observation that underlies the large variability in human populations. In the present study, we used the low responder C3H/HeJ (C3H) and the more sensitive C57BL/6J (C57) strain to find out if resistance and sensitivity to develop pruritus is restricted to only histamine and chloroquine or extends to other known pruritogens as well. We tested five additional commonly known pruritogens. We established dose-response relationships by injecting four concentrations of the pruritogens in the range of 0.3, 1, 3, and ten-fold in the nuchal fold. Then we assessed the scratching behavior for 30 min after injection with an automated custom-designed device based on the bilateral implantation of mini-magnets in the hind paws and on single cages placed within a magnetic coil. We found that the resistance to pruritogens is a general phenotype of the C3H strain and extends to all pruritogens tested, including not only histamine and chloroquine, but also endothelin, trypsin, 5-HT (serotonin), the short peptide SLIGRL, and Lysophosphatidic acid (LPA). C57 was more sensitive to all pruritogens and, in contrast to C3H, dose-response relationships were evident for some of the pruritogens. In general, comparable peak scratch responses were observed for the 0.3-fold concentrations of the pruritogens in C57 whereas C3H required at least the ten-fold concentration and still displayed only between 5 and 33% of the scratch responses observed in C57 for the respective pruritogen. The general resistance to pruritogens and the low level of scratching behavior found in the C3H strain is an interesting trait and represents a model for the study of the heritability of itch. It is accompanied in C3H with a higher sensitivity in assays of nociception.
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Affiliation(s)
- Yanbin Zhang
- Department of Anesthesiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Nicole Richter
- Department of Anesthesiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Christine König
- Department of Anesthesiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas E. Kremer
- Department of Gastroenterology and Hepatology, University Hospital Zürich, Zurich, Switzerland
- Department of Medicine 1, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Katharina Zimmermann
- Department of Anesthesiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
- *Correspondence: Katharina Zimmermann
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Zhang Q, Li T, Niu J, Xiao J, Zhang M, Zhang R, Chen D, Shi Y, Zhang X, Hu X, Yu B, Feng J, Fang Q. Inhibitory effects of antibiotic-induced gut microbiota depletion on acute itch behavior in mice. Brain Res Bull 2022; 190:50-61. [PMID: 36126873 DOI: 10.1016/j.brainresbull.2022.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 09/07/2022] [Accepted: 09/16/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND The gut microbiota is known to be associated with the regulation of many neurological diseases and behaviors, including chronic pain. However, it is unclear whether the gut microbiota is critical to the itch sensation. In this study, we investigated the effects of gut microbiota depletion on acute itch. METHODS First, an antibiotic cocktail was orally administered to deplete the gut microbiota in male C57BL/6 mice. Then, pruritogens were intradermally injected to induce acute itch behavior. In addition, antibiotic-treated mice received transplantation of fecal microbiota from untreated mice, followed by tests for acute itch. The changes in c-Fos expression in trigeminal ganglia (TG) neurons were also investigated by immunofluorescence staining. RESULTS Our results indicated that chronic antibiotic treatment significantly reduced the diversity and richness of the gut microbiota of mice. Compared to vehicle-treated mice, antibiotic-treated mice showed reductions in acute itch behavior induced by compound 48/80, chloroquine (CQ), and serotonin (5-HT), respectively. Moreover, repositioning of microbiota reversed the reductions in acute itch behavior in antibiotic-treated mice. In addition, immunofluorescence staining revealed that antibiotic-treated mice displayed decreased c-Fos expression in ipsilateral TG compared to controls. CONCLUSIONS Our study, for the first time, discovered that antibiotic-induced gut microbiota depletion could reduce acute itch behavior, which may be connected with decreased TG neuronal activity.
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Affiliation(s)
- Qinqin Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Tingting Li
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Jiandong Niu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Jian Xiao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Mengna Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Run Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Dan Chen
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Yonghang Shi
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Xiaodi Zhang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Xuanran Hu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Bowen Yu
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
| | - Jie Feng
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China.
| | - Quan Fang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, School of Basic Medical Sciences, and State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China.
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10
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Critical Players and Therapeutic Targets in Chronic Itch. Int J Mol Sci 2022; 23:ijms23179935. [PMID: 36077340 PMCID: PMC9456029 DOI: 10.3390/ijms23179935] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 12/04/2022] Open
Abstract
Chronic itch is one of the most prominent clinical characteristics of diverse systematic diseases. It is a devastating sensation in pathological diseases. Despite its importance, there are no FDA-labelled drugs specifically geared toward chronic itch. The associated complex pathogenesis and diverse causes escalate chronic itch to being one of the top challenges in healthcare. Humanized antibodies against IL-13, IL-4, and IL-31 proved effective in treatment of itch-associated atopic dermatitis but remain to be validated in chronic itch. There are still no satisfactory anti-itch therapeutics available toward itch-related neuropeptides including GRP, BNP, SST, CGRP, and SP. The newly identified potential itch targets including OSM, NMB, glutamate, periostin, and Serpin E1 have opened new avenues for therapeutic development. Proof-of-principle studies have been successfully performed on antagonists against these proteins and their receptors in itch treatment in animal models. Their translational interventions in humans need to be evaluated. It is of great importance to summarize and compare the newly emerging knowledge on chronic itch and its pathways to promote the development of novel anti-itch therapeutics. The goal of this review is to analyze the different physiologies and pathophysiologies of itch mediators, whilst assessing their suitability as new targets and discussing future therapeutic development.
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11
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Jiang S, Wang YS, Zheng XX, Zhao SL, Wang Y, Sun L, Chen PH, Zhou Y, Tin C, Li HL, Sui JF, Wu GY. Itch-specific neurons in the ventrolateral orbital cortex selectively modulate the itch processing. SCIENCE ADVANCES 2022; 8:eabn4408. [PMID: 35905177 PMCID: PMC9337765 DOI: 10.1126/sciadv.abn4408] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 06/16/2022] [Indexed: 05/31/2023]
Abstract
Itch is a cutaneous sensation that is critical in driving scratching behavior. The long-standing question of whether there are specific neurons for itch modulation inside the brain remains unanswered. Here, we report a subpopulation of itch-specific neurons in the ventrolateral orbital cortex (VLO) that is distinct from the pain-related neurons. Using a Tet-Off cellular labeling system, we showed that local inhibition or activation of these itch-specific neurons in the VLO significantly suppressed or enhanced itch-induced scratching, respectively, whereas the intervention did not significantly affect pain. Conversely, suppression or activation of pain-specific neurons in the VLO significantly affected pain but not itch. Moreover, fiber photometry and immunofluorescence verified that these itch- and pain-specific neurons are distinct in their functional activity and histological location. In addition, the downstream targets of itch- and pain-specific neurons were different. Together, the present study uncovers an important subpopulation of neurons in the VLO that specifically modulates itch processing.
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Affiliation(s)
- Shan Jiang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Yi-Song Wang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Xiao-Xia Zheng
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Shan-Lan Zhao
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Yi Wang
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Lin Sun
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Peng-Hui Chen
- Department of Neurobiology, Army Medical University, Chongqing 400038, China
| | - Yi Zhou
- Department of Neurobiology, Army Medical University, Chongqing 400038, China
| | - Chung Tin
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong, SAR, People’s Republic of China
| | - Hong-Li Li
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
| | - Jian-Feng Sui
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
| | - Guang-Yan Wu
- Experimental Center of Basic Medicine, Army Medical University, Chongqing 400038, China
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing 400038, China
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12
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Weng HJ, Pham QTT, Chang CW, Tsai TF. Druggable Targets and Compounds with Both Antinociceptive and Antipruritic Effects. Pharmaceuticals (Basel) 2022; 15:892. [PMID: 35890193 PMCID: PMC9318852 DOI: 10.3390/ph15070892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/07/2022] [Accepted: 07/15/2022] [Indexed: 12/10/2022] Open
Abstract
Pain and itch are both important manifestations of various disorders, such as herpes zoster, atopic dermatitis, and psoriasis. Growing evidence suggests that both sensations have shared mediators, overlapping neural circuitry, and similarities in sensitization processes. In fact, pain and itch coexist in some disorders. Determining pharmaceutical agents and targets for treating pain and itch concurrently is of scientific and clinical relevance. Here we review the neurobiology of pain and itch and discuss the pharmaceutical targets as well as novel compounds effective for the concurrent treatment of these sensations.
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Affiliation(s)
- Hao-Jui Weng
- Department of Dermatology, Taipei Medical University-Shuang Ho Hospital, New Taipei City 23561, Taiwan;
- Department of Dermatology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- International Ph.D. Program for Cell Therapy and Regeneration Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
| | - Quoc Thao Trang Pham
- International Ph.D. Program for Cell Therapy and Regeneration Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
- Department of Dermatology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City 70000, Vietnam
| | - Chia-Wei Chang
- Department of Dermatology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan;
| | - Tsen-Fang Tsai
- Department of Dermatology, National Taiwan University Hospital, Taipei 100225, Taiwan
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13
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Chen M, He T, Yi XH, Tang MC, Long JH, Wang PJ, Liu J, Yao J, Li HL, Sui JF, Wu GY. Infralimbic cortex–medial striatum projections modulate the itch processing. Exp Neurol 2022; 354:114101. [DOI: 10.1016/j.expneurol.2022.114101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 03/11/2022] [Accepted: 04/26/2022] [Indexed: 11/04/2022]
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14
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Toy PH, Loo YH, Leakasindhu S, Kan CM. Synthesis of Bungeanool, Isobungeanool, Dihydrobungeanool, Tetrahydrobungeanool, Hazaleamide, Lanyuamide III, and Analogues. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/a-1653-4050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractThe bungeanools are a family of alkamide natural products isolated from the pericarps of Zanthoxylum bungeanum (Sichuan pepper), and they are structurally related to the sanshools. While the sanshools, especially hydroxy-α-sanshool, have been studied in a variety of contexts, research regarding the bungeanools has been much more limited. To facilitate their study, we have developed stereoselective syntheses of all four members of this family of compounds by using flexible routes that are also amenable to the synthesis of analogues. The key transformation in the syntheses was the stereoselective triphenylphosphine/phenol-catalyzed isomerization of an alkynoate to the corresponding conjugated E,E-dienoate.
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15
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Toyama S, Tominaga M, Takamori K. Connections between Immune-Derived Mediators and Sensory Nerves for Itch Sensation. Int J Mol Sci 2021; 22:12365. [PMID: 34830245 PMCID: PMC8624544 DOI: 10.3390/ijms222212365] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/09/2021] [Accepted: 11/15/2021] [Indexed: 12/28/2022] Open
Abstract
Although histamine is a well-known itch mediator, histamine H1-receptor blockers often lack efficacy in chronic itch. Recent molecular and cellular based studies have shown that non-histaminergic mediators, such as proteases, neuropeptides and cytokines, along with their cognate receptors, are involved in evocation and modulation of itch sensation. Many of these molecules are produced and secreted by immune cells, which act on sensory nerve fibers distributed in the skin to cause itching and sensitization. This understanding of the connections between immune cell-derived mediators and sensory nerve fibers has led to the development of new treatments for itch. This review summarizes current knowledge of immune cell-derived itch mediators and neuronal response mechanisms, and discusses therapeutic agents that target these systems.
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Affiliation(s)
- Sumika Toyama
- Juntendo Itch Research Center (JIRC), Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Chiba 279-0021, Japan; (S.T.); (M.T.)
| | - Mitsutoshi Tominaga
- Juntendo Itch Research Center (JIRC), Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Chiba 279-0021, Japan; (S.T.); (M.T.)
- Anti-Aging Skin Research Laboratory, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Chiba 279-0021, Japan
| | - Kenji Takamori
- Juntendo Itch Research Center (JIRC), Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Chiba 279-0021, Japan; (S.T.); (M.T.)
- Anti-Aging Skin Research Laboratory, Juntendo University Graduate School of Medicine, 2-1-1 Tomioka, Chiba 279-0021, Japan
- Department of Dermatology, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Chiba 279-0021, Japan
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16
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Estrogens influence female itch sensitivity via the spinal gastrin-releasing peptide receptor neurons. Proc Natl Acad Sci U S A 2021; 118:2103536118. [PMID: 34312228 PMCID: PMC8346901 DOI: 10.1073/pnas.2103536118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many women exhibit a dramatic increase in itch during pregnancy, but the underlying mechanism is unknown. Here, we demonstrate that the female sex steroid hormone estradiol, but not progesterone, enhances itch-related scratching behavior in female rats elicited by histamine, the prototypical itch mediator in humans. This is associated with an enhancement in histamine-evoked activity of a subset of spinal dorsal horn neurons that express a neuropeptide receptor, gastrin-releasing peptide receptor (GRPR), that was previously shown to be involved in spinal cord processing of itch. These findings may account for why itch sensation varies with estrogen levels and provide a basis for treating histamine-related itch diseases in females by targeting GRPR. There are sex differences in somatosensory sensitivity. Circulating estrogens appear to have a pronociceptive effect that explains why females are reported to be more sensitive to pain than males. Although itch symptoms develop during pregnancy in many women, the underlying mechanism of female-specific pruritus is unknown. Here, we demonstrate that estradiol, but not progesterone, enhances histamine-evoked scratching behavior indicative of itch in female rats. Estradiol increased the expression of the spinal itch mediator, gastrin-releasing peptide (GRP), and increased the histamine-evoked activity of itch-processing neurons that express the GRP receptor (GRPR) in the spinal dorsal horn. The enhancement of itch behavior by estradiol was suppressed by intrathecal administration of a GRPR blocker. In vivo electrophysiological analysis showed that estradiol increased the histamine-evoked firing frequency and prolonged the response of spinal GRP-sensitive neurons in female rats. On the other hand, estradiol did not affect the threshold of noxious thermal pain and decreased touch sensitivity, indicating that estradiol separately affects itch, pain, and touch modalities. Thus, estrogens selectively enhance histamine-evoked itch in females via the spinal GRP/GRPR system. This may explain why itch sensation varies with estrogen levels and provides a basis for treating itch in females by targeting GRPR.
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17
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Li X, Yao J, Hu KH, Wu B, Sui JF, Gao J, Wu GY, Liu SL. Differential roles of prelimbic and anterior cingulate cortical region in the modulation of histaminergic and non-histaminergic itch. Behav Brain Res 2021; 411:113388. [PMID: 34052263 DOI: 10.1016/j.bbr.2021.113388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 05/12/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022]
Abstract
Itch is an unpleasant sensation that evokes a desire to scratch. Itch processing in the peripheral and spinal cord has been studied extensively, but the mechanism of itch in the central nervous system is still unclear. Anterior cingulate cortex (ACC) and prelimbic cortex (Prl), two subregions of the prefrontal cortex closely related to emotion and motivation, have been reported to be activated during itching in a series of functional imaging studies. However, the exact role of Prl and the differences between ACC and Prl in itch modulation remains unknown. To directly test the differential roles of ACC and Prl in itch processing, we chemogeneticlly inhibited the caudal ACC and Prl, respectively. We found that inhibition of caudal ACC reduced histaminergic but not non-histaminergic itch-induced scratching behaviors. In contrast, inhibition of Prl reduced both histaminergic and non-histaminergic itch-induced scratching behaviors. Our study provided direct evidence of Prl involvement in itch modulation and revealed the differential roles of caudal ACC and Prl in regulating histaminergic and non-histaminergic itch.
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Affiliation(s)
- Xuan Li
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Juan Yao
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Ke-Hui Hu
- Department of Rehabilitation Medicine, Suining Central Hospital, Suining, 629000, China
| | - Bing Wu
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Jian-Feng Sui
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Jie Gao
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Surgery Research, Daping Hospital, Army Medical University, Chongqing, 400042, China.
| | - Guang-Yan Wu
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China.
| | - Shu-Lei Liu
- Experimental Center of Basic Medicine, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China.
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18
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Fan J, Mishra SK. The emerging role of neuroimmune interactions in atopic dermatitis and itch. FEBS J 2021; 289:2723-2735. [PMID: 33811449 DOI: 10.1111/febs.15860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/13/2021] [Accepted: 04/01/2021] [Indexed: 12/20/2022]
Abstract
Millions of people globally suffer from allergic diseases, and the cases have been rising in the past decades. One of the major manifestations of allergic diseases is itch, which is an unpleasant symptom that triggers the urge to scratch and greatly affects the quality of life. Thus, research on how sensation of itch is detected/transmitted from the contact of the allergen to the nervous system is crucial in mitigating itch. Recent studies have attempted to elucidate the mechanisms of itch in allergic diseases. Here, we aim to review the endogenous mediators released from immune/nonimmune skin cells (that are indirectly involved in the propagation of itch) and the sensory neurons that express receptors for these itch mediators that are associated with direct transmission of itch in cutaneous allergic diseases. As the mechanisms for allergic itch become clearer, new therapeutic approaches to relieve itch are likely to be developed. Recent clinical trials are testing numerous compounds that target the endogenous mediators and their receptors. These studies provide the possibility of more effective itch treatment for allergic diseases.
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Affiliation(s)
- Jennifer Fan
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA
| | - Santosh K Mishra
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.,Comparative Medicine Institute, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.,Program in Genetics, North Carolina State University, Raleigh, NC, USA
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19
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Langedijk JAGM, Beuers UH, Oude Elferink RPJ. Cholestasis-Associated Pruritus and Its Pruritogens. Front Med (Lausanne) 2021; 8:639674. [PMID: 33791327 PMCID: PMC8006388 DOI: 10.3389/fmed.2021.639674] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/12/2021] [Indexed: 12/17/2022] Open
Abstract
Pruritus is a debilitating symptom of various cholestatic disorders, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and inherited progressive familial intrahepatic cholestasis (PFIC). The molecular mechanisms leading to cholestasis-associated pruritus are still unresolved and the involved pruritogens are indecisive. As a consequence of pruritus, patients suffer from sleep deprivation, loss of daytime concentration, auto-mutilation and sometimes even suicidal ideations. Current guideline-approved therapy of cholestasis-associated pruritus includes stepwise administration of several medications, which may alleviate complaints in some, but not all affected patients. Therefore, also experimental therapeutic approaches are required to improve patients' quality of life. This article reviews the current state of research on pruritogens and their receptors, and shortly discusses the most recent experimental therapies.
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Affiliation(s)
| | | | - Ronald P. J. Oude Elferink
- Amsterdam University Medical Centers, Tytgat Institute for Liver and Intestinal Research, Research Institute Amsterdam Gastroenterology, Endocrinology and Metabolism (AGEM), University of Amsterdam, Amsterdam, Netherlands
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20
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Tsagareli MG, Nozadze I, Tsiklauri N, Carstens MI, Gurtskaia G, Carstens E. Thermal Hyperalgesia and Mechanical Allodynia Elicited by Histamine and Non-histaminergic Itch Mediators: Respective Involvement of TRPV1 and TRPA1. Neuroscience 2020; 449:35-45. [PMID: 33010342 PMCID: PMC8219216 DOI: 10.1016/j.neuroscience.2020.09.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/12/2020] [Accepted: 09/22/2020] [Indexed: 02/06/2023]
Abstract
Acute itch is elicited by histamine, as well as non-histaminergic itch mediators including chloroquine, BAM8-22 and Ser-Leu-Ile-Gly-Arg-Leu (SLIGRL). When injected intradermally, histamine binds to histamine H1 and H4 receptors that activate transient receptor potential vanilloid 1 (TRPV1) to depolarize pruriceptors. Chloroquine, BAM8-22, and SLIGRL, respectively, bind to Mas-related G-protein-coupled receptors MrgprA3, MrgprC11, and MrgprC11/PAR2 that in turn activate transient receptor potential ankyrin 1 (TRPA1). In this study we tested if histamine, chloroquine, BAM8-22 and SLIGRL elicit thermal hyperalgesia and mechanical allodynia in adult male mice. We measured the latency of hindpaw withdrawal from a noxious heat stimulus, and the threshold for hindpaw withdrawal from a von Frey mechanical stimulus. Intraplantar injection of histamine resulted in significant thermal hyperalgesia (p < 0.001) and mechanical allodynia (p < 0.001) ipsilaterally that persisted for 1 h. Pretreatment with the TRPV1 antagonist AMG-517 (10 or 20 μg), but not the TRPA1 antagonist HC-030031 (50 or 100 μg), significantly attenuated the magnitude and time course of thermal hyperalgesia and mechanical allodynia elicited by histamine (p < 0.001 for both), indicating that these effects are mediated by TRPV1. In contrast, pretreatment with the TRPA1 antagonist significantly reduced thermal hyperalgesia and mechanical allodynia elicited by chloroquine (p < 0.001 for both ), BAM-822 (p < 0.01, p < 0.001, respectively) and SLGRL (p < 0.05, p < 0.001, respectively), indicating that effects elicited by these non-histaminergic itch mediators require TRPA1. TRPV1 and TRPA1 channel inhibitors thus may have potential use in reducing hyperalgesia and allodynia associated with histaminergic and non-histaminergic itch, respectively.
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Affiliation(s)
| | - Ivliane Nozadze
- Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
| | - Nana Tsiklauri
- Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
| | | | - Gulnaz Gurtskaia
- Beritashvili Center for Experimental Biomedicine, Tbilisi, Georgia
| | - E Carstens
- University of California, Davis, CA, USA.
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21
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Domocos D, Selescu T, Ceafalan LC, Iodi Carstens M, Carstens E, Babes A. Role of 5-HT1A and 5-HT3 receptors in serotonergic activation of sensory neurons in relation to itch and pain behavior in the rat. J Neurosci Res 2020; 98:1999-2017. [PMID: 32537854 DOI: 10.1002/jnr.24633] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/29/2020] [Accepted: 04/10/2020] [Indexed: 12/21/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) released by platelets, mast cells, and immunocytes is a potent inflammatory mediator which modulates pain and itch sensing in the peripheral nervous system. The serotonergic receptors expressed by primary afferent neurons involved in these sensory functions are not fully identified and appear to be to a large extent species dependent. Moreover, the mechanisms through which 5-HT receptor activation is coupled to changes in neuronal excitability have not been completely revealed. Using a combination of in vitro (calcium and voltage imaging and patch-clamp) and in vivo behavioral methods, we used both male and female Wistar rats to provide evidence for the involvement of two 5-HT receptor subtypes, 5-HT1A and 5-HT3, in mediating the sustained and transient effects, respectively, of 5-HT on rat primary afferent neurons involved in pain and itch processing. In addition, our results are consistent with a model in which sustained serotonergic responses triggered via the 5-HT1A receptor are due to closure of background potassium channels, followed by membrane depolarization and action potentials, during which the activation of voltage-gated calcium channels leads to calcium entry. Our results may provide a better understanding of mammalian serotonergic itch signaling.
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Affiliation(s)
- Dan Domocos
- Department of Anatomy, Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Tudor Selescu
- Department of Anatomy, Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Laura Cristina Ceafalan
- Cell Biology, Neuroscience and Experimental Myology Laboratory, 'Victor Babeș' National Institute of Pathology, Bucharest, Romania.,Department of Cellular & Molecular Biology and Histology, School of Medicine, 'Carol Davila' University of Medicine and Pharmacy, Bucharest, Romania
| | - Mirela Iodi Carstens
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, USA
| | - Earl Carstens
- Department of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, USA
| | - Alexandru Babes
- Department of Anatomy, Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
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22
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Khasabov SG, Truong H, Rogness VM, Alloway KD, Simone DA, Giesler GJ. Responses of neurons in the primary somatosensory cortex to itch- and pain-producing stimuli in rats. J Neurophysiol 2020; 123:1944-1954. [PMID: 32292106 DOI: 10.1152/jn.00038.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Understanding of cortical encoding of itch is limited. Injection of pruritogens and algogens into the skin of the cheek produces distinct behaviors, making the rodent cheek a useful model for understanding mechanisms of itch and pain. We examined responses of neurons in the primary somatosensory cortex by application of mechanical stimuli (brush, pressure, and pinch) and stimulations with intradermal injections of pruritic and algesic chemical of receptive fields located on the skin of the cheek in urethane-anesthetized rats. Stimuli included chloroquine, serotonin, β-alanine, histamine, capsaicin, and mustard oil. All 33 neurons studied were excited by noxious mechanical stimuli applied to the cheek. Based on mechanical stimulation most neurons were functionally classified as high threshold. Of 31 neurons tested for response to chemical stimuli, 84% were activated by one or more pruritogens/partial pruritogens. No cells were activated by all five substances. Histamine activated the greatest percentage of neurons and evoked the greatest mean discharge. Importantly, no cells were excited exclusively by pruritogens or partial pruritogens. The recording sites of all neurons that responded to chemical stimuli applied to the cheek were located in the dysgranular zone (DZ) and in deep laminae of the medial border of the vibrissal barrel fields (VBF). Therefore, neurons in the DZ/VBF of rats encode mechanical and chemical pruritogens and algogens. This cortical region appears to contain primarily nociceptive neurons as defined by responses to noxious pinching of the skin. Its role in encoding itch and pain from the cheek of the face needs further study.NEW & NOTEWORTHY Processing of information related to itch sensation at the level of cerebral cortex is not well understood. In this first single-unit electrophysiological study of pruriceptive cortical neurons, we show that neurons responsive to noxious and pruritic stimulation of the cheek of the face are concentrated in a small area of the dysgranular cortex, indicating that these neurons encode information related to itch and pain.
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Affiliation(s)
- Sergey G Khasabov
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Hai Truong
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Victoria M Rogness
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Kevin D Alloway
- Center for Neural Engineering, Penn State University, University Park, Pennsylvania.,Department of Neural and Behavioral Sciences, Penn State University, University Park, Pennsylvania
| | - Donald A Simone
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, Minnesota
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Sharif B, Ase AR, Ribeiro-da-Silva A, Séguéla P. Differential Coding of Itch and Pain by a Subpopulation of Primary Afferent Neurons. Neuron 2020; 106:940-951.e4. [PMID: 32298640 DOI: 10.1016/j.neuron.2020.03.021] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/21/2019] [Accepted: 03/20/2020] [Indexed: 12/21/2022]
Abstract
Itch and pain are distinct unpleasant sensations that can be triggered from the same receptive fields in the skin, raising the question of how pruriception and nociception are coded and discriminated. Here, we tested the multimodal capacity of peripheral first-order neurons, focusing on the genetically defined subpopulation of mouse C-fibers that express the chloroquine receptor MrgprA3. Using optogenetics, chemogenetics, and pharmacology, we assessed the behavioral effects of their selective stimulation in a wide variety of conditions. We show that metabotropic Gq-linked stimulation of these C-afferents, through activation of native MrgprA3 receptors or DREADDs, evokes stereotypical pruriceptive rather than nocifensive behaviors. In contrast, fast ionotropic stimulation of these same neurons through light-gated cation channels or native ATP-gated P2X3 channels predominantly evokes nocifensive rather than pruriceptive responses. We conclude that C-afferents display intrinsic multimodality, and we provide evidence that optogenetic and chemogenetic interventions on the same neuronal populations can drive distinct behavioral outputs.
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Affiliation(s)
- Behrang Sharif
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada; Alan Edwards Centre for Research on Pain, Montreal, QC H3A 0G1, Canada; Department of Physiology, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Ariel R Ase
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada; Alan Edwards Centre for Research on Pain, Montreal, QC H3A 0G1, Canada
| | - Alfredo Ribeiro-da-Silva
- Alan Edwards Centre for Research on Pain, Montreal, QC H3A 0G1, Canada; Department of Pharmacology & Therapeutics, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Philippe Séguéla
- Montreal Neurological Institute, Department of Neurology & Neurosurgery, McGill University, Montreal, QC H3A 2B4, Canada; Alan Edwards Centre for Research on Pain, Montreal, QC H3A 0G1, Canada.
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24
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Abstract
Basic mechanisms and pathways of itch signaling are reviewed, with an emphasis on the progress to date as well as remaining challenges in translating current knowledge to the clinical treatment of chronic itch. Recent studies reveal 3 subsets of pruriceptive sensory neurons highly expressing itch-related genes. Their fibers project into the spinal cord to activate neurons expressing gastrin releasing peptide (GRP) and its receptor (GRPR), which connect to neurons that express the substance P (NK-1) receptor and project to the parabrachial nucleus and thalamus. Spinal inhibitory interneurons release GABA, glycine and dynorphin to modulate segmental itch transmission. However, nearly all pruriceptive neurons also respond to algogens such as capsaicin. Alternative theories of itch-pain discrimination, such as intensity or spatial contrast, are based on the observation that focal stimulation of nociceptive nerve endings elicits itch while more widespread stimulation elicits pain. These findings cloud the issue of a labeled line for itch- a long-debated but currently unresolved challenge. In higher primates there is a dichotomy of histaminergic and non-histaminergic itch-signaling pathways which is less demarcated in rodents, suggesting species differences. A cardinal symptom of chronic itch is alloknesis, i.e., mechanical or touch-evoked itch. Recent evidence indicates that low-threshold mechanosensory afferents can access the spinal itch pathway, but are normally kept in check by inhibitory interneurons expressing neuropeptide Y (NPY). In chronic itch, NPY-mediated inhibition is reduced, allowing touch to excite itch-signaling pathways. These recent advances provide novel targets for development of therapeutic strategies to relieve chronic itch.
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25
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Meng ID, Barton ST, Goodney I, Russell R, Mecum NE. Progesterone Application to the Rat Forehead Produces Corneal Antinociception. Invest Ophthalmol Vis Sci 2019; 60:1706-1713. [PMID: 31013343 PMCID: PMC6736375 DOI: 10.1167/iovs.18-26049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Ocular pain and discomfort are the most defining symptoms of dry eye disease. We determined the ability of topical progesterone to affect corneal sensitivity and brainstem processing of nociceptive inputs. Methods Progesterone or vehicle gel was applied to the shaved forehead in male Sprague Dawley rats. As a site control, gel also was applied to the cheek on the side contralateral to corneal stimulation. Corneal mechanical thresholds were determined using the Cochet-Bonnet esthesiometer in intact and lacrimal gland excision–induced dry eye animals. Eye wipe behaviors in response to hypertonic saline and capsaicin were examined, and corneal mustard oil-induced c-Fos immunohistochemistry was quantified in the brainstem spinal trigeminal nucleus. Results Progesterone gel application to the forehead, but not the contralateral cheek, increased corneal mechanical thresholds in intact and lacrimal gland excision animals beginning <30 minutes after treatment. Subcutaneous injection of the local anesthetic bupivacaine into the forehead region before application of progesterone prevented the increase in corneal mechanical thresholds. Furthermore, progesterone decreased capsaicin-evoked eye wipe behavior in intact animals and hypertonic saline evoked eye wipe behavior in dry eye animals. The number of Fos-positive neurons located in the caudal region of the spinal trigeminal nucleus after corneal mustard oil application was reduced in progesterone-treated animals. Conclusions Results from this study indicate that progesterone, when applied to the forehead, produces analgesia as indicated by increased corneal mechanical thresholds and decreased nociceptive responses to hypertonic saline and capsaicin.
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Affiliation(s)
- Ian D Meng
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, Maine, United States
| | - Stephen T Barton
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States
| | - Ian Goodney
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States
| | - Rachel Russell
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States
| | - Neal E Mecum
- Center for Excellence in the Neurosciences, University of New England, Biddeford, Maine, United States.,Molecular and Biomedical Sciences, University of Maine, Orono, Maine, United States
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26
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Itch sensitization? A systematic review of studies using quantitative sensory testing in patients with chronic itch. Pain 2019; 160:2661-2678. [DOI: 10.1097/j.pain.0000000000001678] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Tsagareli MG, Nozadze I, Tsiklauri N, Gurtskaia G. TRPA1 Channel is Involved in SLIGRL-Evoked Thermal and Mechanical Hyperalgesia in Mice. Med Sci (Basel) 2019; 7:E62. [PMID: 31003539 PMCID: PMC6524052 DOI: 10.3390/medsci7040062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 12/16/2022] Open
Abstract
Persistent itch (pruritus) accompanying dermatologic and systemic diseases can significantly impair the quality of life. It is well known that itch is broadly categorized as histaminergic (sensitive to antihistamine medications) or non-histaminergic. Sensory neurons expressing Mas-related G-protein-coupled receptors (Mrgprs) mediate histamine-independent itch. These receptors have been shown to bind selective pruritogens in the periphery and mediate non-histaminergic itch. For example, mouse MrgprA3 responds to chloroquine (an anti-malarial drug), and are responsible for relaying chloroquine-induced scratching in mice. Mouse MrgprC11 responds to a different subset of pruritogens including bovine adrenal medulla peptide (BAM8-22) and the peptide Ser-Leu-Ile-Gly-Arg-Leu (SLIGRL). On the other hand, the possibility that itch mediators also influence pain is supported by recent findings that most non-histaminergic itch mediators require the transient receptor potential ankyrin 1 (TRPA1) channel. We have recently found a significant increase of thermal and mechanical hyperalgesia induced by non-histaminergic pruritogens chloroquine and BAM8-22, injected into mice hindpaw, for the first 30-45 min. Pretreatment with TRPA1 channel antagonist HC-030031 did significantly reduce the magnitude of this hyperalgesia, as well as significantly shortened the time-course of hyperalgesia induced by chloroquine and BAM8-22. Here, we report that MrgprC11-mediated itch by their agonist SLIGRL is accompanied by heat and mechanical hyperalgesia via the TRPA1 channel. We measured nociceptive thermal paw withdrawal latencies and mechanical thresholds bilaterally in mice at various time points following intra-plantar injection of SLIGRL producing hyperalgesia. When pretreated with the TRPA1 antagonist HC-030031, we found a significant reduction of thermal and mechanical hyperalgesia.
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Affiliation(s)
- Merab G Tsagareli
- Laboratory of Pain and Analgesia, Beritashvili Center for Experimental Biomedicine, Tbilisi 0160, Georgia.
| | - Ivliane Nozadze
- Laboratory of Pain and Analgesia, Beritashvili Center for Experimental Biomedicine, Tbilisi 0160, Georgia.
| | - Nana Tsiklauri
- Laboratory of Pain and Analgesia, Beritashvili Center for Experimental Biomedicine, Tbilisi 0160, Georgia.
| | - Gulnaz Gurtskaia
- Laboratory of Pain and Analgesia, Beritashvili Center for Experimental Biomedicine, Tbilisi 0160, Georgia.
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28
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Lipshetz B, Khasabov SG, Truong H, Netoff TI, Simone DA, Giesler GJ. Responses of thalamic neurons to itch- and pain-producing stimuli in rats. J Neurophysiol 2018; 120:1119-1134. [PMID: 29873617 DOI: 10.1152/jn.00264.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Understanding of processing and transmission of information related to itch and pain in the thalamus is incomplete. In fact, no single unit studies of pruriceptive transmission in the thalamus have yet appeared. In urethane-anesthetized rats, we examined responses of 66 thalamic neurons to itch- and pain- inducing stimuli including chloroquine, serotonin, β-alanine, histamine, and capsaicin. Eighty percent of all cells were activated by intradermal injections of one or more pruritogens. Forty percent of tested neurons responded to injection of three, four, or even five agents. Almost half of the examined neurons had mechanically defined receptive fields that extended onto distant areas of the body. Pruriceptive neurons were located within what appeared to be a continuous cell column extending from the posterior triangular nucleus (PoT) caudally to the ventral posterior medial nucleus (VPM) rostrally. All neurons tested within PoT were found to be pruriceptive. In addition, neurons in this nucleus responded at higher frequencies than did those in VPM, an indication that PoT might prove to be a particularly interesting region for additional studies of itch transmission. NEW & NOTEWORTHY Processing of information related to itch within in the thalamus is not well understood, We show in this, the first single-unit electrophysiological study of responses of thalamic neurons to pruritogens, that itch-responsive neurons are concentrated in two nuclei within the rat thalamus, the posterior triangular, and the ventral posterior medial nuclei.
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Affiliation(s)
- Brett Lipshetz
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
| | - Sergey G Khasabov
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry , Minneapolis, Minnesota
| | - Hai Truong
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
| | - Theoden I Netoff
- Department of Biomedical Engineering, University of Minnesota , Minneapolis, Minnesota
| | - Donald A Simone
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry , Minneapolis, Minnesota
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota , Minneapolis, Minnesota
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29
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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.
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30
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Lazenka ML, Moerke MJ, Townsend EA, Freeman KB, Carroll FI, Negus SS. Dissociable effects of the kappa opioid receptor agonist nalfurafine on pain/itch-stimulated and pain/itch-depressed behaviors in male rats. Psychopharmacology (Berl) 2018; 235:203-213. [PMID: 29063139 PMCID: PMC5750069 DOI: 10.1007/s00213-017-4758-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 10/03/2017] [Indexed: 12/18/2022]
Abstract
RATIONALE Nalfurafine is a G protein signaling-biased kappa opioid receptor (KOR) agonist approved in Japan for second-line treatment of uremic pruritus. Neither nalfurafine nor any other KOR agonist is currently approved anywhere for treatment of pain, but recent evidence suggests that G protein signaling-biased KOR agonists may have promise as candidate analgesics/antipruritics with reduced side effects compared to nonbiased or ß-arrestin-signaling-biased KOR agonists. OBJECTIVES This study compared nalfurafine effects in rats using assays of pain-stimulated and pain-depressed behavior used previously to evaluate other candidate analgesics. Nalfurafine effects were also examined in complementary assays of itch-stimulated and itch-depressed behavior. METHODS Intraperitoneal lactic acid (IP acid) and intradermal serotonin (ID 5HT) served as noxious and pruritic stimuli, respectively, in male Sprague Dawley rats to stimulate stretching (IP acid) or scratching (ID 5HT) or to depress positively reinforced operant responding in an assay of intracranial self-stimulation (ICSS; both stimuli). RESULTS Nalfurafine was equipotent to decrease IP acid-stimulated stretching and ID 5HT-stimulated scratching; however, doses of nalfurafine that decreased these pain/itch-stimulated behaviors also decreased control ICSS performance. Moreover, nalfurafine failed to alleviate either IP acid- or ID 5HT-induced depression of ICSS. CONCLUSIONS These results suggest that nalfurafine-induced decreases in pain/itch-stimulated behaviors may reflect nonselective decreases in motivated behavior rather than analgesia or antipruritus against the noxious and pruritic stimuli used here. This conclusion agrees with the absence of clinical data for nalfurafine analgesia and the weak clinical data for nalfurafine antipruritus. Nalfurafine bias for G protein signaling may not be sufficient for clinically safe and reliable analgesia or antipruritus.
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Affiliation(s)
- Matthew L Lazenka
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Megan J Moerke
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - E Andrew Townsend
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA
| | - Kevin B Freeman
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA
| | - F Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC, USA
| | - S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, 23298, USA.
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31
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Topography of itch: evidence of distinct coding for pruriception in the trigeminal nerve. ACTA ACUST UNITED AC 2017; 2:e2. [PMID: 29862321 PMCID: PMC5965300 DOI: 10.1097/itx.0000000000000002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/22/2016] [Indexed: 12/23/2022]
Abstract
Introduction Little is known about the topographical distribution of pruriception (in particular for nonhistaminergic itch), although conditions with chronic itch frequently occur in distinct anatomic and often bilateral patterns. This study aimed to investigate regional differences in the sensitivity to itch stimuli by assessing the intensity of itch, pain, and cutaneous neurogenic flare evoked by histamine and cowhage in different anatomic regions in 20 healthy volunteers. Methods Itch was induced by 1% histamine applied with a prick lancet or by insertion of 25±5 cowhage spicules in 4 regions: volar/dorsal forearm, lower back, and chin. The duration and intensity of itch and pain following each pruritic stimulus were measured by a continuous visual analogue scale (VAS0-100). Sensitivity to touch-evoked itch was assessed by von Frey filaments and cutaneous flare was quantified by full-field laser perfusion imaging. Results Peak itch intensity was lower at the chin (19.4±3.6) compared with other areas (mean of 3 locations; 41.3±4.4), independently of whether histamine or cowhage was applied (P<0.01). Baseline sensitivity to touch-evoked itch was higher on the chin (P<0.01), but here hyperknesis did not develop in contrast to other areas (P<0.05). Cutaneous flare was more intense but had a smaller dispersion at the chin, compared with other areas (P<0.01). Discussion In conclusion, sensitivity to histaminergic and non-histaminergic itch diverges considerably between body regions. Lower density of pruriceptive CMH and CMI-neurons or distinct neuronal substrates for itch in the mandibular part of the trigeminal area may explain the observed reduced itch and vasomotor responses.
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32
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Hegarty DM, Hermes SM, Yang K, Aicher SA. Select noxious stimuli induce changes on corneal nerve morphology. J Comp Neurol 2017; 525:2019-2031. [PMID: 28213947 DOI: 10.1002/cne.24191] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 02/09/2017] [Accepted: 02/10/2017] [Indexed: 11/10/2022]
Abstract
The surface of the cornea contains the highest density of nociceptive nerves of any tissue in the body. These nerves are responsive to a variety of modalities of noxious stimuli and can signal pain even when activated by low threshold stimulation. Injury of corneal nerves can lead to altered nerve morphology, including neuropathic changes which can be associated with chronic pain. Emerging technologies that allow imaging of corneal nerves in vivo are spawning questions regarding the relationship between corneal nerve density, morphology, and function. We tested whether noxious stimulation of the corneal surface can alter nerve morphology and neurochemistry. We used concentrations of menthol, capsaicin, and hypertonic saline that evoked comparable levels of nocifensive eye wipe behaviors when applied to the ocular surface of an awake rat. Animals were sacrificed and corneal nerves were examined using immunocytochemistry and three-dimensional volumetric analyses. We found that menthol and capsaicin both caused a significant reduction in corneal nerve density as detected with β-tubulin immunoreactivity 2 hr after stimulation. Hypertonic saline did not reduce nerve density, but did cause qualitative changes in nerves including enlarged varicosities that were also seen following capsaicin and menthol stimulation. All three types of noxious stimuli caused a depletion of CGRP from corneal nerves, indicating that all modalities of noxious stimuli evoked peptide release. Our findings suggest that studies aimed at understanding the relationship between corneal nerve morphology and chronic disease may also need to consider the effects of acute stimulation on corneal nerve morphology.
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Affiliation(s)
- Deborah M Hegarty
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Sam M Hermes
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Katherine Yang
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Sue A Aicher
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
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Distribution of hemokinin-1 in the rat trigeminal ganglion and trigeminal sensory nuclear complex. Arch Oral Biol 2017; 79:62-69. [PMID: 28301818 DOI: 10.1016/j.archoralbio.2017.03.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/18/2017] [Accepted: 03/05/2017] [Indexed: 11/24/2022]
Abstract
OBJECTIVE A new mammalian tachykinin peptide encoded in a TAC4 gene was identified and designated as hemokinin-1 (HK-1). A representative of the tachykinin peptide family is substance P (SP), and the function of SP has been well characterized as a pain transmitter or modulator, while it is possible that HK-1 is involved in pruriceptive processing, but, as yet, the distribution of HK-1 peptide in the trigeminal sensory system is still unknown. Thus, the aim of the present study was to elucidate the distribution of HK-1, while comparing the expression of SP, in the trigeminal ganglion and trigeminal sensory nuclear complex. DESIGN The trigeminal ganglion and the brain stem of male SD rats were used in the immunohistochemical study. Since the amino acid sequence in the carboxyl-terminal regions of HK-1 and SP is common, polyclonal antibodies of HK-1 and SP derived from 6 amino acids consisting of amino-terminal regions of these peptides were produced in guinea pig and rabbit, respectively. The immunohistochemical staining of HK-1 and SP was conducted using frozen sections of the trigeminal ganglion and brain stem in rats. RESULTS Immunohistochemical studies revealed the expression of HK-1 in small- and medium-sized trigeminal ganglion neurons, in the paratrigeminal nucleus, and in lamina I of the trigeminal nucleus caudalis, while there was no immunoreactivity of HK-1 in the trigeminal nucleus principalis, trigeminal nucleus oralis, and trigeminal nucleus interpolaris. CONCLUSION These findings indicate that HK-1 is a target molecule for treatment of itch in the orofaicial regions.
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Deseure K, Hans GH. Differential drug effects on spontaneous and evoked pain behavior in a model of trigeminal neuropathic pain. J Pain Res 2017; 10:279-286. [PMID: 28184169 PMCID: PMC5291328 DOI: 10.2147/jpr.s124526] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Baclofen and morphine have shown efficacy against mechanical allodynia after infraorbital nerve chronic constriction injury (IoN-CCI). No drug effects have yet been reported on spontaneous trigeminal neuropathic pain. It has been proposed that the directed face grooming behavior that also develops following IoN-CCI offers a measure of spontaneous trigeminal neuropathic pain. SUBJECTS AND METHODS We examined the effects of a continuous 1-week infusion of 30 mg/day carbamazepine (the first-line drug treatment for trigeminal neuralgia), 1.06 mg/day baclofen, 4.18 mg/day clomipramine, and 5 mg/day morphine on spontaneous and mechanically evoked pain behavior (ie, directed face grooming and von Frey testing) in IoN-CCI rats. RESULTS Isolated face grooming was significantly reduced in rats receiving carbamazepine and baclofen but not in clomipramine- or morphine-treated rats. All drugs showed significant antiallodynic effects; carbamazepine showed the strongest effects, whereas clomipramine had only minor efficacy. CONCLUSION The tested drugs have differential effects in the IoN-CCI model, and different neuropathological mechanisms may underlie the different somatosensory symptoms in this model. A mechanism-based approach may be needed to treat (trigeminal) neuropathic pain. The present data support IoN-CCI as a model of trigeminal neuralgia in which isolated face grooming is used as a measure of spontaneous neuropathic pain.
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Affiliation(s)
- K Deseure
- Department of Medicine, Laboratory for Pain Research, University of Antwerp, Wilrijk
| | - G H Hans
- Multidisciplinary Pain Center, Antwerp University Hospital, Edegem, Belgium
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35
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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]
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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
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36
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Hoeck EA, Marker JB, Gazerani P, H. Andersen H, Arendt-Nielsen L. Preclinical and human surrogate models of itch. Exp Dermatol 2016; 25:750-7. [DOI: 10.1111/exd.13078] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Emil A. Hoeck
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Jens B. Marker
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Parisa Gazerani
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Hjalte H. Andersen
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Lars Arendt-Nielsen
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
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37
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Adrenergic β2-receptor mediates itch hypersensitivity following heterotypic chronic stress in rats. Neuroreport 2016; 26:1003-10. [PMID: 26426856 DOI: 10.1097/wnr.0000000000000458] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Chronic stress is widely considered to trigger or enhance itch, especially for pruritic dermatitis. However, the molecular mechanisms linking chronic stress and itch are still unknown. The present study aimed to elucidate the role of adrenergic signaling in itch hypersensitivity following heterotypic chronic intermittent stress (HIS) in rats. HIS significantly increased hindlimb scratching, but not forepaw swiping, induced by intradermal injection of 5-hydroxytryptamine (5-HT) in the rat cheek. Coadministration of stress mediators such as norepinephrine or epinephrine dose-dependently increased both 5-HT-induced hindlimb scratching and 5-HT-induced forepaw swiping. HIS-induced itch hypersensitivity was attenuated by blockade of sympathetic signaling through guanethidine treatment, and systemic administration of the β-adrenoceptor antagonist propranolol and the β2-adrenoceptor antagonist butoxamine, but not on treatment with an α-adrenoceptor antagonist phentolamine and a β1-adrenoceptor antagonist atenolol. Moreover, HIS selectively increased the expression of β2-adrenoceptors and proinflammatory factors [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nerve growth factor (NGF)] in rat skin. The β-blockers propranolol and butoxamine abolished the upregulation of proinflammatory factors. The β2-adrenoceptor agonist terbutaline was sufficient to enhance the skin expression of TNF-α and IL-1β and to increase 5-HT-induced scratching in naive rats. Pretreatment with TNF-α could increase 5-HT-induced scratching. Together, these results demonstrate that β2-adrenoceptors mediate itch hypersensitivity following chronic stress by inducing proinflammatory factors, such as TNF-α, in the skin.
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Tang M, Wu G, Wang Z, Yang N, Shi H, He Q, Zhu C, Yang Y, Yu G, Wang C, Yuan X, Liu Q, Guan Y, Dong X, Tang Z. Voltage-gated potassium channels involved in regulation of physiological function in MrgprA3-specific itch neurons. Brain Res 2016; 1636:161-171. [PMID: 26874069 DOI: 10.1016/j.brainres.2016.02.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 01/20/2016] [Accepted: 02/04/2016] [Indexed: 12/19/2022]
Abstract
Itch is described as an unpleasant or irritating skin sensation that elicits the desire or reflex to scratch. MrgprA3, one of members of the Mrgprs family, is specifically expressed in a subpopulation of dorsal root ganglion (DRG) in the peripheral nervous system (PNS). These MrgprA3-expressing DRG neurons have been identified as itch-specific neurons. They can be activated by the compound, chloroquine, which is used as a drug to treat malaria. In the present study, we labeled these itch-specific neurons using the method of molecular genetic markers, and then studied their electrophysiological properties. We also recorded the cutaneous MrgprA3(-) neurons retrogradely labeled by Dil dye (MrgprA3(-)-Dil). We first found that MrgprA3(+) neurons have a lower excitability than MrgprA3(-) neurons (MrgprA3(-)-non-Dil and MrgprA3(-)-Dil). The number of action potential (AP) was reduced more obviously in MrgprA3(+) neurons than that of in MrgprA3(-) neurons. In most cases, MrgprA3(+) neurons only generated single AP; however, in MrgprA3(-) neurons, the same stimulation could induce multiple AP firing due to the greater voltage-gated potassium (Kv) current existence in MrgprA3(+) than in MrgprA3(-) neurons. Thus, Kv current plays an important role in the regulation of excitability in itch-specific neurons.
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Affiliation(s)
- Min Tang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China; College of Biology and Environmental Sciences, Jishou University, Jishou, China
| | - Guanyi Wu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China; College of Basic Medicine, Guangxi University of Chinese Medicine, Nanning, China
| | - Zhongli Wang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Niuniu Yang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Hao Shi
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Qian He
- College of Biology and Environmental Sciences, Jishou University, Jishou, China
| | - Chan Zhu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yan Yang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Guang Yu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Changming Wang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Xiaolin Yuan
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Qin Liu
- Department of Anesthesiology, Washington University in St. Louis, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University Schools of Medicine, Baltimore, MD, USA
| | - Xinzhong Dong
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zongxiang Tang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, China.
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Aicher SA, Hermes SM, Hegarty DM. Denervation of the Lacrimal Gland Leads to Corneal Hypoalgesia in a Novel Rat Model of Aqueous Dry Eye Disease. Invest Ophthalmol Vis Sci 2016; 56:6981-9. [PMID: 26513503 DOI: 10.1167/iovs.15-17497] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Some dry eye disease (DED) patients have sensitized responses to corneal stimulation, while others experience hypoalgesia. Many patients have normal tear production, suggesting that reduced tears are not always the cause of DED sensory dysfunction. In this study, we show that disruption of lacrimal innervation can produce hypoalgesia without changing basal tear production. METHODS Injection of a saporin toxin conjugate into the extraorbital lacrimal gland of male Sprague-Dawley rats was used to disrupt cholinergic innervation to the gland. Tear production was assessed by phenol thread test. Corneal sensory responses to noxious stimuli were assessed using eye wipe behavior. Saporin DED animals were compared to animals treated with atropine to produce aqueous DED. RESULTS Cholinergic innervation and acetylcholine content of the lacrimal gland were significantly reduced in saporin DED animals, yet basal tear production was normal. Saporin DED animals demonstrated normal eye wipe responses to corneal application of capsaicin, but showed hypoalgesia to corneal menthol. Corneal nerve fiber density was normal in saporin DED animals. Atropine-treated animals had reduced tear production but normal responses to ocular stimuli. CONCLUSIONS Because only menthol responses were impaired, cold-sensitive corneal afferents appear to be selectively altered in our saporin DED model. Hypoalgesia is not due to reduced tear production, since we did not observe hypoalgesia in an atropine DED model. Corneal fiber density is unaltered in saporin DED animals, suggesting that molecular mechanisms of nociceptive signaling may be impaired. The saporin DED model will be useful for exploring the mechanism underlying corneal hypoalgesia.
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GABAA Receptors in the Central Nucleus of the Amygdala Are Involved in Pain- and Itch-Related Responses. THE JOURNAL OF PAIN 2016; 17:181-9. [DOI: 10.1016/j.jpain.2015.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/09/2015] [Accepted: 10/17/2015] [Indexed: 11/20/2022]
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Assessment of Itch and Pain in Animal Models and Human Subjects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 904:1-22. [PMID: 26900059 DOI: 10.1007/978-94-017-7537-3_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
For the past century, scientists have developed a variety of methods to evaluate itch and pain in both animal models and human subjects to throw light on some of the most important pathways mediating these unpleasant sensations. Discoveries in the mechanisms underlying itch and pain in both physiological and pathological conditions relied greatly upon these studies and may eventually lead to the discovery of new therapeutics. However, it was a much more complicated job to access itch and pain in animal models than in human subjects due to the subjective nature of these sensations. The results could be contradictory or even misleading when applying different methodologies in animal models, especially under pathological conditions with a mixed sensation of itch and pain. This chapter introduces and evaluates some of the classical and newly designed methodologies to access the sensation of itch and pain in animal models as well as human subjects.
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Lipshetz B, Giesler GJ. Effects of scratching and other counterstimuli on responses of trigeminothalamic tract neurons to itch-inducing stimuli in rats. J Neurophysiol 2015; 115:520-9. [PMID: 26538603 DOI: 10.1152/jn.00326.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 11/02/2015] [Indexed: 02/07/2023] Open
Abstract
Counterstimuli such as scratching, pinching, noxious heat and cold, and innocuous cooling and warming have been shown to inhibit itch in humans. In the present study, the effects of each of these counterstimuli were determined on baseline firing rates and on sustained pruriceptive responses of rat trigeminothalamic tract neurons. We found that scratching had little, if any, effect on baseline firing levels but greatly reduced mean pruriceptive firing following scratching for nearly 1 min. None of the other noxious or innocuous counterstimuli significantly inhibited pruriceptive responses. Our results indicate that scratching, but not other counterstimuli, significantly reduces itch-induced responses of trigeminothalamic tract neurons.
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Affiliation(s)
- Brett Lipshetz
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Luo J, Feng J, Liu S, Walters ET, Hu H. Molecular and cellular mechanisms that initiate pain and itch. Cell Mol Life Sci 2015; 72:3201-23. [PMID: 25894692 PMCID: PMC4534341 DOI: 10.1007/s00018-015-1904-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/20/2015] [Accepted: 04/07/2015] [Indexed: 12/17/2022]
Abstract
Somatosensory neurons mediate our sense of touch. They are critically involved in transducing pain and itch sensations under physiological and pathological conditions, along with other skin-resident cells. Tissue damage and inflammation can produce a localized or systemic sensitization of our senses of pain and itch, which can facilitate our detection of threats in the environment. Although acute pain and itch protect us from further damage, persistent pain and itch are debilitating. Recent exciting discoveries have significantly advanced our knowledge of the roles of membrane-bound G protein-coupled receptors and ion channels in the encoding of information leading to pain and itch sensations. This review focuses on molecular and cellular events that are important in early stages of the biological processing that culminates in our senses of pain and itch.
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Affiliation(s)
- Jialie Luo
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA
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Akiyama T, Curtis E, Nguyen T, Carstens MI, Carstens E. Anatomical evidence of pruriceptive trigeminothalamic and trigeminoparabrachial projection neurons in mice. J Comp Neurol 2015; 524:244-56. [PMID: 26099199 DOI: 10.1002/cne.23839] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 06/05/2015] [Accepted: 06/08/2015] [Indexed: 11/06/2022]
Abstract
Itch is relayed to higher centers by projection neurons in the spinal and medullary dorsal horn. We employed a double-label method to map the ascending projections of pruriceptive and nociceptive trigeminal and spinal neurons. The retrograde tracer fluorogold (FG) was stereotaxically injected into the right thalamus or lateral parabrachial area (LPb) in mice. Seven days later, mice received intradermal (id) microinjection of histamine, chloroquine, capsaicin, or vehicle into the left cheek. Histamine, chloroquine, and capsaicin intradermally elicited similar distributions of Fos-positive neurons in the medial aspect of the superficial medullary and spinal dorsal horn from the trigeminal subnucleus caudalis to C2. Among neurons retrogradely labeled from the thalamus, 43%, 8%, and 22% were Fos-positive following id histamine, chloroquine, or capsaicin. Among the Fos-positive neurons following pruritic or capsaicin stimuli, ∼1-2% were retrogradely labeled with FG. Trigeminoparabrachial projection neurons exhibited a higher incidence of double labeling in the superficial dorsal horn. Among the neurons retrogradely labeled from LPb, 36%, 29%, and 33% were Fos positive following id injection of histamine, chloroquine, and capsaicin, respectively. Among Fos-positive neurons elicited by id histamine, chloroquine, and capsaicin, respectively, 3.7%, 4.3%, and 4.1% were retrogradely labeled from LPb. The present results indicate that, overall, relatively small subpopulations of pruriceptive and/or nociceptive neurons innervating the cheek project to thalamus or LPb. These results imply that the vast majority of pruritogen- and algogen-responsive spinal neurons are likely to function as interneurons relaying information to projection neurons and/or participating in segmental nocifensive circuits.
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Affiliation(s)
- Tasuku Akiyama
- Temple Itch Center, Department of Dermatology, Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Eric Curtis
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California, 95616
| | - Tony Nguyen
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California, 95616
| | - Mirela Iodi Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California, 95616
| | - E Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, California, 95616
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Incoherent feed-forward regulatory loops control segregation of C-mechanoreceptors, nociceptors, and pruriceptors. J Neurosci 2015; 35:5317-29. [PMID: 25834056 DOI: 10.1523/jneurosci.0122-15.2015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian skin is innervated by diverse, unmyelinated C fibers that are associated with senses of pain, itch, temperature, or touch. A key developmental question is how this neuronal cell diversity is generated during development. We reported previously that the runt domain transcription factor Runx1 is required to coordinate the development of these unmyelinated cutaneous sensory neurons, including VGLUT3(+) low-threshold c-mechanoreceptors (CLTMs), MrgprD(+) polymodal nociceptors, MrgprA3(+) pruriceptors, MrgprB4(+) c-mechanoreceptors, and others. However, how these Runx1-dependent cutaneous sensory neurons are further segregated is poorly illustrated. Here, we find that the Runx1-dependent transcription factor gene Zfp521 is expressed in, and required for establishing molecular features that define, VGLUT3(+) CLTMs. Furthermore, Runx1 and Zfp521 form a classic incoherent feedforward loop (I-FFL) in controlling molecular identities that normally belong to MrgprD(+) neurons, with Runx1 and Zfp51 playing activator and repressor roles, respectively (in genetic terms). A knock-out of Zfp521 allows prospective VGLUT3 lineage neurons to acquire MrgprD(+) neuron identities. Furthermore, Runx1 might form other I-FFLs to regulate the expression of MrgprA3 and MrgprB4, a mechanism preventing these genes from being expressed in Runx1-persistent VGLUT3(+) and MrgprD(+) neurons. The evolvement of these I-FFLs provides an explanation for how modality-selective sensory subtypes are formed during development and may also have intriguing implications for sensory neuron evolution and sensory coding.
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Valtcheva MV, Samineni VK, Golden JP, Gereau RW, Davidson S. Enhanced nonpeptidergic intraepidermal fiber density and an expanded subset of chloroquine-responsive trigeminal neurons in a mouse model of dry skin itch. THE JOURNAL OF PAIN 2015; 16:346-56. [PMID: 25640289 DOI: 10.1016/j.jpain.2015.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 01/08/2015] [Accepted: 01/16/2015] [Indexed: 12/13/2022]
Abstract
UNLABELLED Chronic pruritic conditions are often associated with dry skin and loss of epidermal barrier integrity. In this study, repeated application of acetone and ether followed by water (AEW) to the cheek skin of mice produced persistent scratching behavior with no increase in pain-related forelimb wiping, indicating the generation of itch without pain. Cheek skin immunohistochemistry showed a 64.5% increase in total epidermal innervation in AEW-treated mice compared to water-treated controls. This increase was independent of scratching, because mice prevented from scratching by Elizabethan collars showed similar hyperinnervation. To determine the effects of dry skin treatment on specific subsets of peripheral fibers, we examined Ret-positive, calcitonin gene-related peptide (CGRP)-positive, and glial cell line-derived neurotrophic factor family receptor α3 (GFRα3)-positive intraepidermal fiber density. AEW treatment increased Ret-positive fibers but not CGRP-positive or GFRα3-positive fibers, suggesting that a specific subset of nonpeptidergic fibers could contribute to dry skin itch. To test whether trigeminal ganglion neurons innervating the cheek exhibited altered excitability after AEW treatment, primary cultures of retrogradely labeled neurons were examined using whole-cell patch clamp electrophysiology. AEW treatment produced no differences in measures of excitability compared to water-treated controls. In contrast, a significantly higher proportion of trigeminal ganglion neurons was responsive to the nonhistaminergic pruritogen chloroquine after AEW treatment. We conclude that nonpeptidergic, Ret-positive fibers and chloroquine-sensitive neurons may contribute to dry skin pruritus. PERSPECTIVE This study examines the underlying neurobiological mechanisms of persistent dry skin itch. Our results indicate that nonpeptidergic epidermal hyperinnervation and nonhistaminergic pruritic receptors are potential targets for chronic pruritus.
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Affiliation(s)
- Manouela V Valtcheva
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri; Medical Scientist Training Program, Washington University in St. Louis, St. Louis, Missouri
| | - Vijay K Samineni
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Judith P Golden
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Robert W Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Steve Davidson
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri.
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Abstract
Protease-activated receptors (PARs) have been implicated in a variety of physiological functions, as well as somatosensation and particularly itch and pain. Considerable attention has focused on PARs following the finding they are upregulated in the skin of atopic dermatitis patients. The present review focuses on recent studies showing that PARs are critically involved in itch and sensitization of itch. PARs are expressed by diverse cell types including primary sensory neurons, keratinocytes, and immune cells and are activated by proteases that expose a tethered ligand. Endogenous proteases are also released from diverse cell types including keratinocytes and immune cells. Exogenous proteases released from certain plants and insects contacting the skin can also induce itch. Increased levels of proteases in the skin contribute to inflammation that is often accompanied by chronic itch which is not predominantly mediated by histamine. The neural pathway signaling itch induced by activation of PARs is distinct from that mediating histamine-induced itch. In addition, there is evidence that PARs play an important role in sensitization of itch signaling under conditions of chronic itch. These recent findings suggest that PARs and other molecules involved in the itch-signaling pathway are good targets to develop novel treatments for most types of chronic itch that are poorly treated with antihistamines.
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Affiliation(s)
- Tasuku Akiyama
- Department of Dermatology, Anatomy and Cell Biology/Temple Itch Center, Temple University School of Medicine, Philadelphia, PA, 19140, USA
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Jansen NA, Giesler GJ. Response characteristics of pruriceptive and nociceptive trigeminoparabrachial tract neurons in the rat. J Neurophysiol 2015; 113:58-70. [PMID: 25298386 PMCID: PMC4294571 DOI: 10.1152/jn.00596.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 10/06/2014] [Indexed: 12/11/2022] Open
Abstract
We tested the possibility that the trigeminoparabrachial tract (VcPbT), a projection thought to be importantly involved in nociception, might also contribute to sensation of itch. In anesthetized rats, 47 antidromically identified VcPbT neurons with receptive fields involving the cheek were characterized for their responses to graded mechanical and thermal stimuli and intradermal injections of pruritogens (serotonin, chloroquine, and β-alanine), partial pruritogens (histamine and capsaicin), and an algogen (mustard oil). All pruriceptive VcPbT neurons were responsive to mechanical stimuli, and more than half were additionally responsive to thermal stimuli. The majority of VcPbT neurons were activated by injections of serotonin, histamine, capsaicin, and/or mustard oil. A subset of neurons were inhibited by injection of chloroquine. The large majority of VcPbT neurons projected to the ipsilateral and/or contralateral external lateral parabrachial and Kölliker-Fuse nuclei, as evidenced by antidromic mapping techniques. Analyses of mean responses and spike-timing dynamics of VcPbT neurons suggested clear differences in firing rates between responses to noxious and pruritic stimuli. Comparisons between the present data and those previously obtained from trigeminothalamic tract (VcTT) neurons demonstrated several differences in responses to some pruritogens. For example, responses of VcPbT neurons to injection of serotonin often endured for nearly an hour and showed a delayed peak in discharge rate. In contrast, responses of VcTT neurons endured for roughly 20 min and no delayed peak of firing was noted. Thus the longer duration responses to 5-HT and the delay in peak firing of VcPbT neurons better matched behavioral responses to stimulation in awake rats than did those of VcTT neurons. The results indicate that VcPbT neurons may have important roles in the signaling of itch as well as pain.
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Affiliation(s)
- Nico A Jansen
- Department of Neuroscience, Erasmus University Medical Center, Rotterdam, The Netherlands; and
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
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Takanami K, Sakamoto H, Matsuda KI, Satoh K, Tanida T, Yamada S, Inoue K, Oti T, Sakamoto T, Kawata M. Distribution of gastrin-releasing peptide in the rat trigeminal and spinal somatosensory systems. J Comp Neurol 2014; 522:1858-73. [PMID: 24254931 DOI: 10.1002/cne.23506] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/30/2013] [Accepted: 11/15/2013] [Indexed: 12/12/2022]
Abstract
Gastrin-releasing peptide (GRP) has recently been identified as an itch-specific neuropeptide in the spinal sensory system in mice, but there are no reports of the expression and distribution of GRP in the trigeminal sensory system in mammals. We characterized and compared GRP-immunoreactive (ir) neurons in the trigeminal ganglion (TG) with those in the rat spinal dorsal root ganglion (DRG). GRP immunoreactivity was expressed in 12% of TG and 6% of DRG neurons and was restricted to the small- and medium-sized type cells. In both the TG and DRG, many GRP-ir neurons also expressed substance P and calcitonin gene-related peptide, but not isolectin B4 . The different proportions of GRP and transient receptor potential vanilloid 1 double-positive neurons in the TG and DRG imply that itch sensations via the TG and DRG pathways are transmitted through distinct mechanisms. The distribution of the axon terminals of GRP-ir primary afferents and their synaptic connectivity with the rat trigeminal sensory nuclei and spinal dorsal horn were investigated by using light and electron microscopic histochemistry. Although GRP-ir fibers were rarely observed in the trigeminal sensory nucleus principalis, oralis, and interpolaris, they were predominant in the superficial layers of the trigeminal sensory nucleus caudalis (Vc), similar to the spinal dorsal horn. Ultrastructural analysis revealed that GRP-ir terminals contained clear microvesicles and large dense-cored vesicles, and formed asymmetric synaptic contacts with a few dendrites in the Vc and spinal dorsal horn. These results suggest that GRP-dependent orofacial and spinal pruriceptive inputs are processed mainly in the superficial laminae of the Vc and spinal dorsal horn.
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Affiliation(s)
- Keiko Takanami
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-8566, Japan
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Takanami K, Sakamoto H. The Gastrin-Releasing Peptide Receptor (GRPR) in the Spinal Cord as a Novel Pharmacological Target. Curr Neuropharmacol 2014; 12:434-43. [PMID: 25426011 PMCID: PMC4243033 DOI: 10.2174/1570159x12666140923201432] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/28/2014] [Accepted: 09/10/2014] [Indexed: 12/02/2022] Open
Abstract
Gastrin-releasing peptide (GRP) is a mammalian neuropeptide that acts through the G protein-coupled receptor, GRP receptor (GRPR). Increasing evidence indicates that GRPR-mediated signaling in the central nervous system plays an important role in many physiological processes in mammals. Additionally, we have recently reported that the GRP system within the lumbosacral spinal cord not only controls erection but also triggers ejaculation in male rats. This system of GRP neurons is sexually dimorphic, being prominent in male rats but vestigial or absent in females. It is suggested that the sexually dimorphic GRP/GRPR system in the lumbosacral spinal cord plays a critical role in the regulation of male sexual function. In parallel, it has been reported that the somatosensory GRP/GRPR system in the spinal cord contributes to the regulation of itch specific transmission independently of the pain transmission. Interestingly, these two distinct functions in the same spinal region are both regulated by the neuropeptide, GRP. In this report, we review findings on recently identified GRP/GRPR systems in the spinal cord. These GRP/GRPR systems in the spinal cord provide new insights into pharmacological treatments for psychogenic erectile dysfunction as well as for chronic pruritus.
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Affiliation(s)
- Keiko Takanami
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
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