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Lee S, Wei ET, Selescu T, Babes A, Park J, Kim J, Chung B, Park C, Kim HO. Histamine- and pruritogen-induced itch is inhibited by a TRPM8 agonist: a randomized vehicle-controlled human trial. Br J Dermatol 2024; 190:885-894. [PMID: 38345103 DOI: 10.1093/bjd/ljae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 11/27/2023] [Accepted: 02/05/2024] [Indexed: 04/11/2024]
Abstract
BACKGROUND Allergies often present challenges in managing itch and the effects of histamine. Cooling agents that act via transient receptor potential melastatin 8 (TRPM8) agonism have shown potential in itch management. However, animal studies on itch have limitations, as animals cannot communicate subjective events and their fur-coated skin differs from that of humans. Human studies offer more direct and reliable information. OBJECTIVES To investigate the effects of a specific TRPM8 agonist gel (cryosim-1) on itch induced by various pruritogens in human skin. METHODS Calcium imaging experiments determined the binding of cryosim-1 and histamine to their respective receptors. Thirty healthy volunteers underwent skin prick tests with pruritogens and a control vehicle. Itch and pain intensity were measured using a numerical rating scale (NRS) across 10 min. Participants were randomly assigned to pretreatments with vehicle or TRPM8 agonist gel. Tests were repeated at a later date, and skin moisture, transepidermal water loss and mechanical sensitivity were measured. RESULTS The in vitro study confirmed that histamine is not a TRPM8 agonist and cryosim-1 does not act as an agonist or antagonist on the human histamine 1 receptor. The TRPM8 agonist gel significantly reduced the itch intensity for all pruritogens compared with the vehicle-only gel. It also reduced itch NRS and the integrated itch score. Mechanical sensitivity was also reduced. CONCLUSIONS The specific TRPM8 agonist gel effectively suppressed human skin itch induced by various pruritogens. These versatile actions suggest that cooling agents may be promising treatments for multiple forms of itch stimuli.
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Affiliation(s)
- Soyeon Lee
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Edward T Wei
- School of Public Health, University of California, Berkeley, CA, USA
| | - Tudor Selescu
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Alexandru Babes
- Department of Anatomy, Animal Physiology and Biophysics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | - Jinseo Park
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Jincheol Kim
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Boyoung Chung
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Chunwook Park
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Hye One Kim
- Department of Dermatology, Hallym University Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea
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Schwarzenauer M, Rukwied RM, Lampert A, Rolke R, Namer B. Electrical matrix stimulation suppresses acute itch independently of activation of sleeping nociceptors. Eur J Pain 2024; 28:285-296. [PMID: 37715607 DOI: 10.1002/ejp.2177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/24/2023] [Accepted: 08/19/2023] [Indexed: 09/17/2023]
Abstract
INTRODUCTION Itch can be reduced by pain. Activation of sleeping nociceptors (CMi) is a crucial mechanism for the peripheral component of intense and long-lasting pain. Thus, activation of CMi might be especially effective in itch reduction. Electrical stimulation using sinusoidal pulses activates CMi with tolerable pain intensity, whereas short rectangular pulses with low intensity do not. In humans, histaminergic itch is mediated by histamine-sensitive CMi, whereas other pruritogens activate polymodal nociceptors (CM). METHODS In a psychophysical approach in a balanced crossover repeated-measures design in healthy volunteers, we activated nociceptors by two different electrical stimulation paradigms via a matrix electrode: 4 Hz sinusoidal pulses that activate C-nociceptors including CMi or 4 Hz rectangular stimuli to activate nociceptors excluding CMi. After 5-min stimulation, itch was induced by either histamine iontophoresis or application of cowhage spicules. Itch ratings were assessed via a numerical rating scale (NRS). RESULTS Electrical 4 Hz sine wave stimulation (0.1 mA) with low pain ratings of 1.5 (NRS; 0-10) induced an axon reflex erythema (3 cm2 ), indicating activation of CMi, whereas rectangular 0.2 ms pulses (average 0.91 mA) with the same pain rating did not. Both electrical stimulation paradigms reduced itch magnitude over time evoked by either histamine or cowhage to a similar extent. Peak maximum itch evoked by histamine was reduced by both stimulation paradigms, but not cowhage maximum itch. DISCUSSION Since electrical stimulation with the rectangular pulse paradigm reduces itch to a similar extent as the sine wave stimulation paradigm, the input of CMi is not necessarily required for itch suppression. The input of A-fibres and polymodal nociceptors, similarly, as also achieved by scratching, seems to be sufficient for both forms of chemically evoked itch. SIGNIFICANCE Since activation of CMi does not provide additional benefit for itch suppression, spinal pain pathways transmitted via CM versus CMi have differential effects on itch-processing circuits. This is important knowledge for using electrical matrix stimulation as itch suppressor since activation of sleeping nociceptors either requires significantly painful stimulation paradigms or specialized stimulation paradigms as sinusoidal pulses. An alternative approach using half-sine wave pulses with low pain intensity activating specifically polymodal nociceptors to suppress itch via matrix electrode stimulation may be considered.
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Affiliation(s)
- M Schwarzenauer
- IZKF Research Group Neuroscience, Medical Faculty RWTH Aachen University, Aachen, Germany
- Department of Palliative Medicine, Medical Faculty RWTH Aachen University, Aachen, Germany
| | - R M Rukwied
- Department of Experimental Pain Research, Mannheim Center for Translation Neuroscience (MCTN), Medical Faculty Mannheim, University of Heidelberg, Heidelberg, Germany
| | - A Lampert
- Department for Neurophysiology, Medical Faculty RWTH Aachen University, Aachen, Germany
| | - R Rolke
- Department of Palliative Medicine, Medical Faculty RWTH Aachen University, Aachen, Germany
| | - B Namer
- IZKF Research Group Neuroscience, Medical Faculty RWTH Aachen University, Aachen, Germany
- Department for Neurophysiology, Medical Faculty RWTH Aachen University, Aachen, Germany
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3
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Hage A, Knoeri J, Leveziel L, Majoulet A, Buffault J, Labbé A, Baudouin C. [From ocular itching to eye rubbing: a review of the literature]. J Fr Ophtalmol 2023; 46:173-184. [PMID: 36635208 DOI: 10.1016/j.jfo.2022.09.009] [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: 05/02/2022] [Revised: 09/20/2022] [Accepted: 09/22/2022] [Indexed: 01/11/2023]
Abstract
Ocular itching and eye rubbing are frequent complaints in an ophthalmology practice. Numerous studies address the consequences of eye rubbing, such as keratoconus. However, there are few studies concerning the pathophysiology of itching, its transmission pathways, or its interactions with eye rubbing. Through this literature review, we will address the various clinical, physiological and therapeutic aspects of this pair of symptoms with a variety of ocular consequences. We will then describe the state of the art in itching and scratching in dermatology, in order to draw a parallel between these two vicious cycles. A better understanding of the pathophysiology of ocular itching and eye rubbing, as well as new studies based on dermatological data, might allow more appropriate clinical management of our patients and their symptoms.
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Affiliation(s)
- A Hage
- Department of Ophthalmology III, National Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, Service 3-Pr Christophe Baudouin, 28, rue de Charenton, 75012, Paris, France.
| | - J Knoeri
- Department of Ophthalmology V, NATIONAL Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012, Paris, France
| | - L Leveziel
- Department of Ophthalmology V, NATIONAL Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012, Paris, France
| | - A Majoulet
- Department of Ophthalmology III, National Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, Service 3-Pr Christophe Baudouin, 28, rue de Charenton, 75012, Paris, France
| | - J Buffault
- Department of Ophthalmology III, National Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, Service 3-Pr Christophe Baudouin, 28, rue de Charenton, 75012, Paris, France
| | - A Labbé
- Department of Ophthalmology III, National Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, Service 3-Pr Christophe Baudouin, 28, rue de Charenton, 75012, Paris, France; Department of Ophthalmology, Ambroise Paré Hospital, AP-HP, Université de Versailles Saint-Quentin en Yvellines, 9, avenue Charles de Gaulle, 92100, Boulogne-Billancourt, France; Sorbonne Université, inserm, CNRS, Institut de la Vision, 17, rue Moreau, 75012, Paris, France
| | - C Baudouin
- Department of Ophthalmology III, National Hospital Centre for Ophthalmology Quinze-Vingts, IHU FOReSIGHT, Service 3-Pr Christophe Baudouin, 28, rue de Charenton, 75012, Paris, France; Department of Ophthalmology, Ambroise Paré Hospital, AP-HP, Université de Versailles Saint-Quentin en Yvellines, 9, avenue Charles de Gaulle, 92100, Boulogne-Billancourt, France; Sorbonne Université, inserm, CNRS, Institut de la Vision, 17, rue Moreau, 75012, Paris, France
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4
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Chen QY, Zhuo M. Glutamate acts as a key neurotransmitter for itch in the mammalian spinal cord. Mol Pain 2023; 19:17448069231152101. [PMID: 36604775 PMCID: PMC9846298 DOI: 10.1177/17448069231152101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Itch sensation is one of the major sensory experiences of humans and animals. Recent studies using genetic deletion techniques have proposed that gastrin-releasing peptide (GRP) is a key neurotransmitter for itch in the spinal cord. However, these studies are mainly based on behavioral responses and lack direct electrophysiological evidence that GRP indeed mediates itch information between primary afferent fibers and spinal dorsal horn neurons. In this review, we reviewed recent studies using different experimental approaches and proposed that glutamate but not GRP acts as the key neurotransmitter in the primary afferents in the transmission of itch. GRP is more likely to serve as an itch-related neuromodulator. In the cerebral cortex, we propose that the anterior cingulate cortex (ACC) plays a significant role in both itch and pain sensations. Only behavioral measurement of itch (scratching) is not sufficient for itch measurement, since scratching the itching area also produces pleasure. Integrative experimental approaches as well as better behavioral scoring models are needed to help to understand the neuronal mechanism of itch and aid future treatment for patients with pruritic diseases.
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Affiliation(s)
- Qi-Yu Chen
- Qingdao International Academician
Park, International Institute for Brain
Research, Qingdao, China,CAS Key Laboratory of Brain
Connectome and Manipulation, Interdisciplinary Center for Brain Information, The
Brain Cognition and Brain Disease Institute, Shenzhen-Hong Kong Institute of
Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen Institute of
Advanced Technology, Chinese Academy of Sciences Shenzhen
Institute of Advanced Technology, Shenzhen, China
| | - Min Zhuo
- Qingdao International Academician
Park, International Institute for Brain
Research, Qingdao, China,Department of Physiology, Faculty
of Medicine, University of Toronto, Toronto, ON, Canada,Min Zhuo, Institute of Brain Research,
Qingdao International Academician Park, Qingdao 266199, China.
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5
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Kaneko T, Kuwaki T, Kashiwadani H. Hypothalamic orexinergic neurons modulate pain and itch in an opposite way: pain relief and itch exacerbation. J Physiol Sci 2022; 72:21. [PMID: 35996084 DOI: 10.1186/s12576-022-00846-0] [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: 03/09/2022] [Accepted: 08/07/2022] [Indexed: 11/10/2022]
Abstract
Pain and itch are recognized as antagonistic sensations; pain suppresses itch and inhibition of pain generates itch. There is still a lack of evidence about the neural mechanism of the interaction between pain and itch in the central nervous system. In this study, we focused on the orexin (ORX) neurons in the lateral hypothalamus (LH), which mediate various "defense responses" when animals confront stressors. We found that the scratching behaviors induced by the pruritogen were significantly suppressed in ORX-neuron-ablated (ORX-abl) mice. The exaggerated pain behavior and attenuated itch behavior observed in ORX-abl mice indicated that ORX neurons modulate pain and itch in an opposite way, i.e., pain relief and itch exacerbation. In addition, most of the ORX neurons responded to both pain and itch input. Our results suggest that ORX neurons inversely regulate pain- and itch-related behaviors, which could be understood as a defense response to cope with stress environment.
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Affiliation(s)
- Tatsuroh Kaneko
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Hideki Kashiwadani
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan.
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Kawano T, Atsukawa M, Tsubota A, Shimada N, Toyoda H, Takaguchi K, Tani J, Morishita A, Hiraoka A, Mikami S, Ishikawa T, Okubo H, Watanabe T, Okubo T, Arai T, Hayama K, Itokawa N, Kondo C, Iwakiri K. Shorter pruritus period and milder disease stage are associated with response to nalfurafine hydrochloride in patients with chronic liver disease. Sci Rep 2022; 12:7311. [PMID: 35508514 PMCID: PMC9068920 DOI: 10.1038/s41598-022-11431-1] [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: 02/02/2022] [Accepted: 04/21/2022] [Indexed: 11/09/2022] Open
Abstract
Nalfurafine hydrochloride, a selective κ-opioid receptor agonist has been approved for pruritus in patients with chronic liver disease. However, not all patients respond to nalfurafine hydrochloride. The aim of this study was to clarify the efficacy of nalfurafine hydrochloride. The subjects were patients with chronic liver disease complicated by pruritus who were treated with nalfurafine hydrochloride between May, 2015, and May, 2021. The degree of pruritus was evaluated based on the Visual Analog Scale (VAS) score and the Kawashima's pruritus score. Nalfurafine hydrochloride 2.5 μg was orally administered once a day for 12 weeks. A decrease in the VAS score of ≥ 25 mm or the Kawashima's pruritus score of ≥ 1 scores was designated as relevant response. The former of ≥ 50 mm or the latter of ≥ 2 scores as remarkable response. The 326 patients who were evaluated the efficacy at 12 weeks. The median time suffering from pruritus to administration of nalfurafine hydrochloride was 4 months. The median VAS score improved from 70.0 mm before administration to 40.0 and 30.0 mm at 4 and 12 weeks of treatment, respectively. On multivariate analysis, shorter itching period and lower FIB-4 index value were extracted as the independent factors related to remarkable responder. On multivariate analysis, shorter itching period was extracted as the only independent factor related to relevant responder. In conclusion, this study suggested nalfurafine hydrochloride treatment markedly improves pruritus in patients with chronic liver disease. A short pruritus period and less-advanced fibrosis were associated with response to nalfurafine hydrochloride.
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Affiliation(s)
- Tadamichi Kawano
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan
| | - Masanori Atsukawa
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan.
| | - Akihito Tsubota
- Core Research Facilities, The Jikei University School of Medicine, Tokyo, Japan
| | - Noritomo Shimada
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Otakanomori Hospital, Kashiwa, Japan
| | - Hidenori Toyoda
- Department of Gastroenterology, Ogaki Municipal Hospital, Ogaki, Japan
| | - Koichi Takaguchi
- Department of Hepatology, Kagawa Prefectural Central Hospital, Takamatsu, Japan
| | - Joji Tani
- Department of Gastroenterology, Kagawa University Graduate School of Medicine, Kagawa, Japan
| | - Asahiro Morishita
- Department of Gastroenterology, Kagawa University Graduate School of Medicine, Kagawa, Japan
| | - Atsushi Hiraoka
- Gastroenterology Center, Ehime Prefectural Central Hospital, Matsuyama, Japan
| | - Shigeru Mikami
- Department of Internal Medicine, Division of Gastroenterology, Kikkoman General Hospital, Noda, Japan
| | - Toru Ishikawa
- Department of Gastroenterology, Saiseikai Niigata Hospital, Niigata, Japan
| | - Hironao Okubo
- Department of Gastroenterology, Juntendo University Nerima Hospital, Tokyo, Japan
| | - Tsunamasa Watanabe
- Division of Gastroenterology and Hepatology, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Tomomi Okubo
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Japan
| | - Taeang Arai
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan
| | - Korenobu Hayama
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Japan
| | - Norio Itokawa
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan
| | - Chisa Kondo
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan
| | - Katsuhiko Iwakiri
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan
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7
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Hu L, Jiang GY, Wang YP, Hu ZB, Zhou BY, Zhang L, Song NN, Huang Y, Chai GD, Chen JY, Lang B, Xu L, Liu JL, Li Y, Wang QX, Ding YQ. The role of PTEN in primary sensory neurons in processing itch and thermal information in mice. Cell Rep 2022; 39:110724. [PMID: 35443189 DOI: 10.1016/j.celrep.2022.110724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 03/03/2022] [Accepted: 03/30/2022] [Indexed: 12/01/2022] Open
Abstract
PTEN is known as a tumor suppressor and plays essential roles in brain development. Here, we report that PTEN in primary sensory neurons is involved in processing itch and thermal information in adult mice. Deletion of PTEN in the dorsal root ganglia (DRG) is achieved in adult Drg11-CreER: PTENflox/flox (PTEN CKO) mice with oral administration of tamoxifen, and CKO mice develop pathological itch and elevated itch responses on exposure to various pruritogens. PTEN deletion leads to ectopic expression of TRPV1 and MrgprA3 in IB4+ non-peptidergic DRG neurons, and the TRPV1 is responsive to capsaicin. Importantly, the elevated itch responses are no longer present in Drg11-CreER: PTENflox/flox: TRPV1flox/flox (PTEN: TRPV1 dCKO) mice. In addition, thermal stimulation is enhanced in PTEN CKO mice but blunted in dCKO mice. PTEN-involved regulation of itch-related gene expression in DRG neurons provides insights for understanding molecular mechanism of itch and thermal sensation at the spinal level.
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Affiliation(s)
- Ling Hu
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Guan-Yu Jiang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ying-Ping Wang
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Zhi-Bin Hu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Bing-Yao Zhou
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Lei Zhang
- Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ning-Ning Song
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Ying Huang
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China
| | - Guo-Dong Chai
- Department of Anesthesiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Jia-Yin Chen
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China
| | - Bing Lang
- Department of Psychiatry, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Lin Xu
- Laboratory of Learning and Memory, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Jun-Ling Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Yong Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Qing-Xiu Wang
- Department of Anesthesiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China.
| | - Yu-Qiang Ding
- Department of Laboratory Animal Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; Key Laboratory of Arrhythmias, Ministry of Education, East Hospital, and Department of Anatomy and Neurobiology, Tongji University School of Medicine, Shanghai 200092, China.
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8
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Ádám D, Arany J, Tóth KF, Tóth BI, Szöllősi AG, Oláh A. Opioidergic Signaling-A Neglected, Yet Potentially Important Player in Atopic Dermatitis. Int J Mol Sci 2022; 23:4140. [PMID: 35456955 PMCID: PMC9027603 DOI: 10.3390/ijms23084140] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 02/04/2023] Open
Abstract
Atopic dermatitis (AD) is one of the most common skin diseases, the prevalence of which is especially high among children. Although our understanding about its pathogenesis has substantially grown in recent years, and hence, several novel therapeutic targets have been successfully exploited in the management of the disease, we still lack curative treatments for it. Thus, there is an unmet societal demand to identify further details of its pathogenesis to thereby pave the way for novel therapeutic approaches with favorable side effect profiles. It is commonly accepted that dysfunction of the complex cutaneous barrier plays a central role in the development of AD; therefore, the signaling pathways involved in the regulation of this quite complex process are likely to be involved in the pathogenesis of the disease and can provide novel, promising, yet unexplored therapeutic targets. Thus, in the current review, we aim to summarize the available potentially AD-relevant data regarding one such signaling pathway, namely cutaneous opioidergic signaling.
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Affiliation(s)
- Dorottya Ádám
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.Á.); (J.A.); (K.F.T.); (B.I.T.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - József Arany
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.Á.); (J.A.); (K.F.T.); (B.I.T.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Kinga Fanni Tóth
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.Á.); (J.A.); (K.F.T.); (B.I.T.)
- Doctoral School of Molecular Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Balázs István Tóth
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.Á.); (J.A.); (K.F.T.); (B.I.T.)
| | - Attila Gábor Szöllősi
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
| | - Attila Oláh
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (D.Á.); (J.A.); (K.F.T.); (B.I.T.)
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9
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Piyush Shah D, Barik A. The Spino-Parabrachial Pathway for Itch. Front Neural Circuits 2022; 16:805831. [PMID: 35250493 PMCID: PMC8891797 DOI: 10.3389/fncir.2022.805831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/03/2022] [Indexed: 11/13/2022] Open
Abstract
Itch-induced scratching is an evolutionarily conserved behavioral response that protects organisms from potential parasites/irritants in their immediate vicinity. How the exposure to a pruritogen is translated to the perception of itch and how that perception drives scratching directed towards the site of exposure remains poorly understood. In this review, we focus on the recent findings that shed light on the neural pathways in the brain that underlie itch-induced scratching. We compare the molecularly defined itch pathways with the known pain circuits as they have anatomical and functional overlap. We review the roles played by the neurons in the spinoparabrachial pathway-comprising of the neurons in the spinal cord and the parabrachial nucleus (PBN), which acts as a hub for transmitting itch information across the brain. Lastly, we deliberate on scratching as a behavioral measure of the intensity of itch and its implication in unraveling the underlying supraspinal mechanisms. In summary, we provide a resource on the recent advances and discuss a path forward on our understanding of the neural circuits for itch.
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Affiliation(s)
| | - Arnab Barik
- Centre for Neuroscience, Indian Institute of Science, Bengaluru, India
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10
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Abstract
Itch is one of the most primal sensations, being both ubiquitous and important for the well-being of animals. For more than a century, a desire to understand how itch is encoded by the nervous system has prompted the advancement of many theories. Within the past 15 years, our understanding of the molecular and neural mechanisms of itch has undergone a major transformation, and this remarkable progress continues today without any sign of abating. Here I describe accumulating evidence that indicates that itch is distinguished from pain through the actions of itch-specific neuropeptides that relay itch information to the spinal cord. According to this model, classical neurotransmitters transmit, inhibit and modulate itch information in a context-, space- and time-dependent manner but do not encode itch specificity. Gastrin-releasing peptide (GRP) is proposed to be a key itch-specific neuropeptide, with spinal neurons expressing GRP receptor (GRPR) functioning as a key part of a convergent circuit for the conveyance of peripheral itch information to the brain.
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11
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Mu D, Sun YG. Circuit Mechanisms of Itch in the Brain. J Invest Dermatol 2021; 142:23-30. [PMID: 34662562 DOI: 10.1016/j.jid.2021.09.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/21/2021] [Accepted: 09/21/2021] [Indexed: 12/12/2022]
Abstract
Itch is an unpleasant somatic sensation with the desire to scratch, and it consists of sensory, affective, and motivational components. Acute itch serves as a critical protective mechanism because an itch-evoked scratching response will help to remove harmful substances invading the skin. Recently, exciting progress has been made in deciphering the mechanisms of itch at both the peripheral nervous system and the CNS levels. Key neuronal subtypes and circuits have been revealed for ascending transmission and the descending modulation of itch. In this review, we mainly summarize the current understanding of the central circuit mechanisms of itch in the brain.
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Affiliation(s)
- Di Mu
- Department of Anesthesiology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yan-Gang Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences, Shanghai, China; Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China.
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12
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Kim HS, Hashimoto T, Fischer K, Bernigaud C, Chosidow O, Yosipovitch G. Scabies itch: an update on neuroimmune interactions and novel targets. J Eur Acad Dermatol Venereol 2021; 35:1765-1776. [PMID: 33960033 DOI: 10.1111/jdv.17334] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/23/2021] [Indexed: 12/14/2022]
Abstract
Frequently described as 'the worst itch' one can ever experience scabies itch is the hallmark of Sarcoptes scabiei mite infestation. Notably, the itchiness often persists for weeks despite scabicides therapy. The mechanism of scabies itch is not yet fully understood, and effective treatment modalities are still missing which can severely affect the quality of life. The aim of this review is to provide an overview of the scope of itch in scabies and highlight candidate mechanisms underlying this itch. We herein discuss scabies itch, with a focus on the nature, candidate underlying mechanisms and treatment options. We also synthesize this information with current understanding of the mechanisms contributing to non-histaminergic itch in other conditions. Itch is a major problem in scabies and can lead to grave consequences. We provide the latest insights on host-mite interaction, secondary microbial infection and neural sensitization with special emphasis on keratinocytes and mast cells to better understand the mechanism of itch in scabies. Also, the most relevant current modalities remaining under investigation that possess promising perspectives for scabies itch (i.e. protease-activated receptor-2 (PAR-2) inhibitor, Mas-related G protein-coupled receptor X2 (MRGPRX2) antagonist) are discussed. Greater understanding of these diverse mechanisms may provide a rational basis for the development of improved and targeted approaches to control itch in individuals with scabies.
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Affiliation(s)
- H S Kim
- Dr Philip Frost Department of Dermatology and Cutaneous Surgery, Miami Itch Center, Miller School of Medicine, University of Miami, Miami, FL, USA.,Department of Dermatology, Incheon St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea
| | - T Hashimoto
- Department of Dermatology, National Defense Medical College, Saitama, Japan
| | - K Fischer
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - C Bernigaud
- Faculté de Santé de Créteil et Service de Dermatologie, APHP, Hôpital Henri-Mondor, Université Paris-Est, Créteil, France.,Research Group Dynamic, EA7380, Faculté de Santé de Créteil, Ecole Nationale Vétérinaire d'Alfort, USC ANSES, Université Paris-Est Créteil, Créteil, France
| | - O Chosidow
- Faculté de Santé de Créteil et Service de Dermatologie, APHP, Hôpital Henri-Mondor, Université Paris-Est, Créteil, France.,Research Group Dynamic, EA7380, Faculté de Santé de Créteil, Ecole Nationale Vétérinaire d'Alfort, USC ANSES, Université Paris-Est Créteil, Créteil, France
| | - G Yosipovitch
- Dr Philip Frost Department of Dermatology and Cutaneous Surgery, Miami Itch Center, Miller School of Medicine, University of Miami, Miami, FL, USA
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13
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Samineni VK, Grajales-Reyes JG, Grajales-Reyes GE, Tycksen E, Copits BA, Pedersen C, Ankudey ES, Sackey JN, Sewell SB, Bruchas MR, Gereau RW. Cellular, circuit and transcriptional framework for modulation of itch in the central amygdala. eLife 2021; 10:68130. [PMID: 34032210 PMCID: PMC8172243 DOI: 10.7554/elife.68130] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 05/24/2021] [Indexed: 01/06/2023] Open
Abstract
Itch is an unpleasant sensation that elicits robust scratching and aversive experience. However, the identity of the cells and neural circuits that organize this information remains elusive. Here, we show the necessity and sufficiency of chloroquine-activated neurons in the central amygdala (CeA) for both itch sensation and associated aversion. Further, we show that chloroquine-activated CeA neurons play important roles in itch-related comorbidities, including anxiety-like behaviors, but not in some aversive and appetitive behaviors previously ascribed to CeA neurons. RNA-sequencing of chloroquine-activated CeA neurons identified several differentially expressed genes as well as potential key signaling pathways in regulating pruritis. Finally, viral tracing experiments demonstrate that these neurons send projections to the ventral periaqueductal gray that are critical in modulation of itch. These findings reveal a cellular and circuit signature of CeA neurons orchestrating behavioral and affective responses to pruritus in mice.
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Affiliation(s)
- Vijay K Samineni
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Jose G Grajales-Reyes
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Medical Scientist Training Program, Washington University School of MedicineSt. LouisUnited States
- Neuroscience Program, Washington University School of MedicineSt. LouisUnited States
| | - Gary E Grajales-Reyes
- Department of Pathology & Immunology, Washington University School of MedicineSt. LouisUnited States
| | - Eric Tycksen
- Genome Technology Access Center, Washington University School of MedicineSeattleUnited States
| | - Bryan A Copits
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Christian Pedersen
- Department of Biomedical Engineering, University of WashingtonSeattleUnited States
| | - Edem S Ankudey
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Julian N Sackey
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Sienna B Sewell
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
| | - Michael R Bruchas
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Departments of Anesthesiology and Pharmacology, University of WashingtonSeattleUnited States
- Departmentsof Neuroscience and Biomedical Engineering, Washington University School of MedicineSt.LouisUnited States
| | - Robert W Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Department of Biomedical Engineering, University of WashingtonSeattleUnited States
- Departmentsof Neuroscience and Biomedical Engineering, Washington University School of MedicineSt.LouisUnited States
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14
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Wang S, Song P, Ma R, Wang Y, Yu B, Wang M, Wang M, Shen J, Dai Y, Wang Y, Xie W. Research on Characteristic of Chronic Spontaneous Urticaria Based on Multiscale Entropy. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2021; 2021:6691356. [PMID: 34122619 PMCID: PMC8172304 DOI: 10.1155/2021/6691356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 03/21/2021] [Accepted: 04/12/2021] [Indexed: 12/12/2022]
Abstract
Chronic spontaneous urticaria (CSU) is a common skin disease which symptom is local pruritus and pain. In medicine, researchers take a certain point that the brain is the control center of CSU, but in previous experiments, the researchers found that cerebellum also had a certain effect on CSU. In order to find out the influence of CSU in the brain and cerebellum, we collected the brain resting-state fMRI data from 40 healthy controls and 32 CSU patients and used DPABI to preprocess. We calculated the entropy values of five scales by using multiscale entropy (MSE) and the average entropy values of two groups' BOLD signals; 15 regions with significant differences were found which not only had a more detailed impact in the brain but also had an impact in the cerebellum, such as precentral gyrus, lenticular putamen, and vermis of cerebellum. In addition, we found that compared with the healthy controls, the entropy values of CSU patients showed two trends which need further study. The advantage of our experiment is that the multiscale entropy value is used to get more influence regions of CSU in the brain and cerebellum. The results of this paper may provide some help for the pathological study of CSU.
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Affiliation(s)
- Shujuan Wang
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Ping Song
- Department of Dermatology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Rong Ma
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Yanzhong Wang
- School of Population Health & Environmental Sciences, Faculty of Life Science and Medicine, King's College London, London, UK
- Suzhou Fanhan Information Technology Co., Ltd, China
| | - Bin Yu
- Department of Dermatology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Min Wang
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Meiqi Wang
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Jihong Shen
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Yuntao Dai
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
| | - Yuming Wang
- Department of Dermatology, Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
| | - Wanqing Xie
- College of Mathematical Sciences, Harbin Engineering University, Harbin 150001, China
- Suzhou Fanhan Information Technology Co., Ltd, China
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15
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Wang Z, Jiang C, Yao H, Chen O, Rahman S, Gu Y, Zhao J, Huh Y, Ji RR. Central opioid receptors mediate morphine-induced itch and chronic itch via disinhibition. Brain 2021; 144:665-681. [PMID: 33367648 DOI: 10.1093/brain/awaa430] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 09/29/2020] [Accepted: 10/22/2020] [Indexed: 02/27/2024] Open
Abstract
Opioids such as morphine are mainstay treatments for clinical pain conditions. Itch is a common side effect of opioids, particularly as a result of epidural or intrathecal administration. Recent progress has advanced our understanding of itch circuits in the spinal cord. However, the mechanisms underlying opioid-induced itch are not fully understood, although an interaction between µ-opioid receptor (MOR) and gastrin-releasing peptide receptor (GRPR) in spinal GRPR-expressing neurons has been implicated. In this study we investigated the cellular mechanisms of intrathecal opioid-induced itch by conditional deletion of MOR-encoding Oprm1 in distinct populations of interneurons and sensory neurons. We found that intrathecal injection of the MOR agonists morphine or DAMGO elicited dose-dependent scratching as well as licking and biting, but this pruritus was totally abolished in mice with a specific Oprm1 deletion in Vgat+ neurons [Oprm1-Vgat (Slc32a1)]. Loss of MOR in somatostatin+ interneurons and TRPV1+ sensory neurons did not affect morphine-induced itch but impaired morphine-induced antinociception. In situ hybridization revealed Oprm1 expression in 30% of inhibitory and 20% of excitatory interneurons in the spinal dorsal horn. Whole-cell recordings from spinal cord slices showed that DAMGO induced outward currents in 9 of 19 Vgat+ interneurons examined. Morphine also inhibited action potentials in Vgat+ interneurons. Furthermore, morphine suppressed evoked inhibitory postsynaptic currents in postsynaptic Vgat- excitatory neurons, suggesting a mechanism of disinhibition by MOR agonists. Notably, morphine-elicited itch was suppressed by intrathecal administration of NPY and abolished by spinal ablation of GRPR+ neurons with intrathecal injection of bombesin-saporin, whereas intrathecal GRP-induced itch response remained intact in mice lacking Oprm1-Vgat. Intrathecal bombesin-saporin treatment reduced the number of GRPR+ neurons by 97% in the lumber spinal cord and 91% in the cervical spinal cord, without changing the number of Oprm1+ neurons. Additionally, chronic itch from DNFB-induced allergic contact dermatitis was decreased by Oprm1-Vgat deletion. Finally, naloxone, but not peripherally restricted naloxone methiodide, inhibited chronic itch in the DNFB model and the CTCL model, indicating a contribution of central MOR signalling to chronic itch. Our findings demonstrate that intrathecal morphine elicits itch via acting on MOR on spinal inhibitory interneurons, leading to disinhibition of the spinal itch circuit. Our data also provide mechanistic insights into the current treatment of chronic itch with opioid receptor antagonist such as naloxone.
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Affiliation(s)
- Zilong Wang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Changyu Jiang
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Hongyu Yao
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ouyang Chen
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Sreya Rahman
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yun Gu
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Junli Zhao
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yul Huh
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ru-Rong Ji
- Center for Translational Pain Medicine, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
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16
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Boulanger N, Wikel S. Induced Transient Immune Tolerance in Ticks and Vertebrate Host: A Keystone of Tick-Borne Diseases? Front Immunol 2021; 12:625993. [PMID: 33643313 PMCID: PMC7907174 DOI: 10.3389/fimmu.2021.625993] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/22/2021] [Indexed: 12/23/2022] Open
Abstract
Ticks and tick transmitted infectious agents are increasing global public health threats due to increasing abundance, expanding geographic ranges of vectors and pathogens, and emerging tick-borne infectious agents. Greater understanding of tick, host, and pathogen interactions will contribute to development of novel tick control and disease prevention strategies. Tick-borne pathogens adapt in multiple ways to very different tick and vertebrate host environments and defenses. Ticks effectively pharmacomodulate by its saliva host innate and adaptive immune defenses. In this review, we examine the idea that successful synergy between tick and tick-borne pathogen results in host immune tolerance that facilitates successful tick infection and feeding, creates a favorable site for pathogen introduction, modulates cutaneous and systemic immune defenses to establish infection, and contributes to successful long-term infection. Tick, host, and pathogen elements examined here include interaction of tick innate immunity and microbiome with tick-borne pathogens; tick modulation of host cutaneous defenses prior to pathogen transmission; how tick and pathogen target vertebrate host defenses that lead to different modes of interaction and host infection status (reservoir, incompetent, resistant, clinically ill); tick saliva bioactive molecules as important factors in determining those pathogens for which the tick is a competent vector; and, the need for translational studies to advance this field of study. Gaps in our understanding of these relationships are identified, that if successfully addressed, can advance the development of strategies to successfully disrupt both tick feeding and pathogen transmission.
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Affiliation(s)
- Nathalie Boulanger
- Fédération de Médecine Translationnelle - UR7290, Early Bacterial Virulence, Group Borrelia, Université de Strasbourg, Strasbourg, France.,Centre National de Référence Borrelia, Centre Hospitalier Universitaire, Strasbourg, France
| | - Stephen Wikel
- Department of Medical Sciences, Frank H. Netter, M.D., School of Medicine, Quinnipiac University, Hamden, CT, United States
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17
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Najafi P, Dufor O, Ben Salem D, Misery L, Carré JL. Itch processing in the brain. J Eur Acad Dermatol Venereol 2020; 35:1058-1066. [PMID: 33145804 DOI: 10.1111/jdv.17029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 09/17/2020] [Accepted: 10/02/2020] [Indexed: 01/04/2023]
Abstract
Itch is a sensation defined as the urge to scratch. The central mechanisms of itch are being increasingly studied. These studies are usually based on experimental itch induction methods, which can be classified into the following categories: histamine-induced, induction by other non-histamine chemicals (e.g. cowhage), physically induced (e.g. electrical) and mentally induced (e.g. audio-visual). Because pain has been more extensively studied, some extrapolations to itch can be proposed and verified by experiments. Recent studies suggest that the itch-processing network in the brain could be disrupted in certain diseases. This disruption could be related to the implication of new regions or the exclusion of already engaged brain regions from itch-processing network in the brain.
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Affiliation(s)
| | - O Dufor
- LIEN, Univ Brest, Brest, France.,LabISEN Yncréa Ouest ISEN, Brest, France
| | - D Ben Salem
- Univ Brest, LaTIM, INSERM, UMR 1101, Brest, France.,University Hospital of Brest, Brest, France
| | - L Misery
- LIEN, Univ Brest, Brest, France.,University Hospital of Brest, Brest, France
| | - J-L Carré
- LIEN, Univ Brest, Brest, France.,University Hospital of Brest, Brest, France
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18
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Itch: A Paradigm of Neuroimmune Crosstalk. Immunity 2020; 52:753-766. [PMID: 32433948 DOI: 10.1016/j.immuni.2020.04.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/07/2020] [Accepted: 04/17/2020] [Indexed: 02/07/2023]
Abstract
Although the medical definition of itch has been in existence for 360 years, only in the last 20 years have we begun to understand the basic mechanisms that underlie this unique sensation. Therapeutics that specifically target chronic itch as a pathologic entity are currently still not available. Recent seminal advances in itch circuitry within the nervous system have intersected with discoveries in immunology in unexpected ways to rapidly inform emerging treatment strategies. The current review aims to introduce these basic concepts in itch biology and highlight how distinct immunologic pathways integrate with recently identified itch-sensory circuits in the nervous system to inform a major new paradigm of neuroimmunology and therapeutic development for chronic itch.
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19
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Low-Threshold Mechanosensitive VGLUT3-Lineage Sensory Neurons Mediate Spinal Inhibition of Itch by Touch. J Neurosci 2020; 40:7688-7701. [PMID: 32895292 DOI: 10.1523/jneurosci.0091-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 07/07/2020] [Accepted: 07/20/2020] [Indexed: 11/21/2022] Open
Abstract
Innocuous mechanical stimuli, such as rubbing or stroking the skin, relieve itch through the activation of low-threshold mechanoreceptors. However, the mechanisms behind this inhibition remain unknown. We presently investigated whether stroking the skin reduces the responses of superficial dorsal horn neurons to pruritogens in male C57BL/6J mice. Single-unit recordings revealed that neuronal responses to chloroquine were enhanced during skin stroking, and this was followed by suppression of firing below baseline levels after the termination of stroking. Most of these neurons additionally responded to capsaicin. Stroking did not suppress neuronal responses to capsaicin, indicating state-dependent inhibition. Vesicular glutamate transporter 3 (VGLUT3)-lineage sensory nerves compose a subset of low-threshold mechanoreceptors. Stroking-related inhibition of neuronal responses to chloroquine was diminished by optogenetic inhibition of VGLUT3-lineage sensory nerves in male and female Vglut3-cre/NpHR-EYFP mice. Conversely, in male and female Vglut3-cre/ChR2-EYFP mice, optogenetic stimulation of VGLUT3-lineage sensory nerves inhibited firing responses of spinal neurons to pruritogens after the termination of stimulation. This inhibition was nearly abolished by spinal delivery of the κ-opioid receptor antagonist nor-binaltorphimine dihydrochloride, but not the neuropeptide Y receptor Y1 antagonist BMS193885. Optogenetic stimulation of VGLUT3-lineage sensory nerves inhibited pruritogen-evoked scratching without affecting mechanical and thermal pain behaviors. Therefore, VGLUT3-lineage sensory nerves appear to mediate inhibition of itch by tactile stimuli.SIGNIFICANCE STATEMENT Rubbing or stroking the skin is known to relieve itch. We investigated the mechanisms behind touch-evoked inhibition of itch in mice. Stroking the skin reduced the activity of itch-responsive spinal neurons. Optogenetic inhibition of VGLUT3-lineage sensory nerves diminished stroking-evoked inhibition, and optogenetic stimulation of VGLUT3-lineage nerves inhibited pruritogen-evoked firing. Together, our results provide a mechanistic understanding of touch-evoked inhibition of itch.
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20
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Abstract
Itch is a unique sensation that helps organisms scratch away external threats; scratching itself induces an immune response that can contribute to more itchiness. Itch is induced chemically in the peripheral nervous system via a wide array of receptors. Given the superficial localization of itch neuron terminals, cells that dwell close to the skin contribute significantly to itch. Certain mechanical stimuli mediated by recently discovered circuits also contribute to the itch sensation. Ultimately, in the spinal cord, and likely in the brain, circuits that mediate touch, pain, and itch engage in cross modulation. Much of itch perception is still a mystery, but we present in this review the known ligands and receptors associated with itch. We also describe experiments and findings from investigations into the spinal and supraspinal circuitry responsible for the sensation of itch.
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Affiliation(s)
- Mark Lay
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA;,
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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21
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Abstract
Itch, in particular chronic forms, has been widely recognized as an important clinical problem, but much less is known about the mechanisms of itch in comparison with other sensory modalities such as pain. Recently, considerable progress has been made in dissecting the circuit mechanisms of itch at both the spinal and supraspinal levels. Major components of the spinal neural circuit underlying both chemical and mechanical itch have now been identified, along with the circuits relaying ascending transmission and the descending modulation of itch. In this review, we summarize the progress in elucidating the neural circuit mechanism of itch at spinal and supraspinal levels.
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Affiliation(s)
- Xiao-Jun Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science & Intelligence Technology, Chinese Academy of Sciences, 320 Yue-Yang Road, 200031, Shanghai, China
- University of Chinese Academy of Sciences, 19A Yu-quan Road, 100049, Beijing, China
| | - Yan-Gang Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science & Intelligence Technology, Chinese Academy of Sciences, 320 Yue-Yang Road, 200031, Shanghai, China.
- Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, 201210, Shanghai, China.
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22
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Sung Kim H, Yosipovitch G. THE SKIN MICROBIOTA AND ITCH: Is There a Link? THE JOURNAL OF CLINICAL AND AESTHETIC DERMATOLOGY 2020; 13:S39-S46. [PMID: 33282109 PMCID: PMC7710288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Itch is an unpleasant sensation that emanates primarily from the skin. The chemical mediators that drive neuronal activity originate from a complex interaction between keratinocytes, inflammatory cells, nerve endings, and the skin microbiota, relaying itch signals to the brain. Stress also exacerbates itch via the skin-brain axis. Recently, the microbiota has surfaced as a major player to regulate this axis, notably during stress settings aroused by actual or perceived homeostatic challenge. The routes of communication between the microbiota and brain are slowly being unraveled and involve neurochemicals (i.e., acetylcholine, histamine, catecholamines, and corticotropin) that originate from the microbiota itself. By focusing on itch biology and by referring to the more established field of pain research, this review examines the possible means by which the skin microbiota contributes to itch.
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Affiliation(s)
- Hei Sung Kim
- Dr. Kim is with the Department of Dermatology and Cutaneous Surgery at Miami Itch Center, Miller School of Medicine at University of Miami in Miami, Florida, the Department of Dermatology at Incheon St. Mary's Hospital, The Catholic University of Korea in Seoul, Korea, and the Department of Biomedicine and Health Sciences, at The Catholic University of Korea in Seoul, Korea
- Dr. Yosipovitch is with the Department of Dermatology and Cutaneous Surgery at Miami Itch Center, Miller School of Medicine at the University of Miami in Miami, Florida
| | - Gil Yosipovitch
- Dr. Kim is with the Department of Dermatology and Cutaneous Surgery at Miami Itch Center, Miller School of Medicine at University of Miami in Miami, Florida, the Department of Dermatology at Incheon St. Mary's Hospital, The Catholic University of Korea in Seoul, Korea, and the Department of Biomedicine and Health Sciences, at The Catholic University of Korea in Seoul, Korea
- Dr. Yosipovitch is with the Department of Dermatology and Cutaneous Surgery at Miami Itch Center, Miller School of Medicine at the University of Miami in Miami, Florida
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23
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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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Deng YZ, Lu YC, Wu WW, Cheng L, Zan GY, Chai JR, Wang YJ, Chen Z, Liu JG. Anteromedial thalamic nucleus to anterior cingulate cortex inputs modulate histaminergic itch sensation. Neuropharmacology 2020; 168:108028. [DOI: 10.1016/j.neuropharm.2020.108028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/25/2020] [Accepted: 03/02/2020] [Indexed: 01/13/2023]
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The Skin Microbiota and Itch: Is There a Link? J Clin Med 2020; 9:jcm9041190. [PMID: 32331207 PMCID: PMC7230651 DOI: 10.3390/jcm9041190] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/18/2020] [Accepted: 04/20/2020] [Indexed: 02/07/2023] Open
Abstract
Itch is an unpleasant sensation that emanates primarily from the skin. The chemical mediators that drive neuronal activity originate from a complex interaction between keratinocytes, inflammatory cells, nerve endings and the skin microbiota, relaying itch signals to the brain. Stress also exacerbates itch via the skin–brain axis. Recently, the microbiota has surfaced as a major player to regulate this axis, notably during stress settings aroused by actual or perceived homeostatic challenge. The routes of communication between the microbiota and brain are slowly being unraveled and involve neurochemicals (i.e., acetylcholine, histamine, catecholamines, corticotropin) that originate from the microbiota itself. By focusing on itch biology and by referring to the more established field of pain research, this review examines the possible means by which the skin microbiota contributes to itch.
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The Neuropathic Itch Caused by Pseudorabies Virus. Pathogens 2020; 9:pathogens9040254. [PMID: 32244386 PMCID: PMC7238046 DOI: 10.3390/pathogens9040254] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
Pseudorabies virus (PRV) is an alphaherpesvirus related to varicella-zoster virus (VZV) and herpes simplex virus type 1 (HSV1). PRV is the causative agent of Aujeskzy’s disease in swine. PRV infects mucosal epithelium and the peripheral nervous system (PNS) of its host where it can establish a quiescent, latent infection. While the natural host of PRV is the swine, a broad spectrum of mammals, including rodents, cats, dogs, and cattle can be infected. Since the nineteenth century, PRV infection is known to cause a severe acute neuropathy, the so called “mad itch” in non-natural hosts, but surprisingly not in swine. In the past, most scientific efforts have been directed to eradicating PRV from pig farms by the use of effective marker vaccines, but little attention has been given to the processes leading to the mad itch. The main objective of this review is to provide state-of-the-art information on the mechanisms governing PRV-induced neuropathic itch in non-natural hosts. We highlight similarities and key differences in the pathogenesis of PRV infections between non-natural hosts and pigs that might explain their distinctive clinical outcomes. Current knowledge on the neurobiology and possible explanations for the unstoppable itch experienced by PRV-infected animals is also reviewed. We summarize recent findings concerning PRV-induced neuroinflammatory responses in mice and address the relevance of this animal model to study other alphaherpesvirus-induced neuropathies, such as those observed for VZV infection.
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Li NQ, Tang Y, Huang ST, Liu XT, Zeng LP, Li H, Wan L. Modulation of NR1 receptor by CaMKIIα plays an important role in chronic itch development in mice. Brain Res Bull 2020; 158:66-76. [PMID: 32112850 DOI: 10.1016/j.brainresbull.2020.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/22/2020] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
Intractable scratching is the characteristic of chronic itch, which represents a great challenge in clinical practice. However, the mechanism underlying chronic itch development is largely unknown. In the present study, we investigated the role of NMDA receptor in acute itch and in development of chronic itch. A mouse model was developed by painting DNFB to induce allergic contact dermatitis (ACD). We found that the expression of pNR1, which is a subunit of NMDA receptor, was significantly increased in the dorsal root ganglion in the DNFB model. The DNFB-evoked spontaneous scratching was blocked by the NMDA antagonist D-AP-5, the calcium-calmodulin-dependent protein kinase (CaMK) inhibitor KN-93, a CaMKIIα siRNA and the PKC inhibitor LY317615. Moreover, activation of PKC did not reverse the CaMKIIα knockdown-induced decrease in scratching, suggesting that PKC functions upstream of CaMKIIα. Thus, our study indicates that modulation of NR1 receptor by CaMKIIα plays an important role in the development of chronic itch.
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Affiliation(s)
- Nan-Qi Li
- Department of Pain Management, The State Key Clinical Specialty in Pain Medicine, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China
| | - Yang Tang
- Department of Pain Management, The State Key Clinical Specialty in Pain Medicine, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China
| | - Si-Ting Huang
- Department of Pain Management, The State Key Clinical Specialty in Pain Medicine, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China
| | - Xue-Ting Liu
- Guangdong Provincial Key Laboratory of Allergy & Clinic Immunology, Sino-French Hoffmann Institute, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China
| | - Li-Ping Zeng
- Guangdong Provincial Key Laboratory of Allergy & Clinic Immunology, Sino-French Hoffmann Institute, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China
| | - Hui Li
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China
| | - Li Wan
- Department of Pain Management, The State Key Clinical Specialty in Pain Medicine, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, 510260, P.R. China.
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Samineni VK, Grajales-Reyes JG, Sundaram SS, Yoo JJ, Gereau RW. Cell type-specific modulation of sensory and affective components of itch in the periaqueductal gray. Nat Commun 2019; 10:4356. [PMID: 31554789 PMCID: PMC6761157 DOI: 10.1038/s41467-019-12316-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 08/28/2019] [Indexed: 01/07/2023] Open
Abstract
Itch is a distinct aversive sensation that elicits a strong urge to scratch. Despite recent advances in our understanding of the peripheral basis of itch, we know very little regarding how central neural circuits modulate acute and chronic itch processing. Here we establish the causal contributions of defined periaqueductal gray (PAG) neuronal populations in itch modulation in mice. Chemogenetic manipulations demonstrate bidirectional modulation of scratching by neurons in the PAG. Fiber photometry studies show that activity of GABAergic and glutamatergic neurons in the PAG is modulated in an opposing manner during chloroquine-evoked scratching. Furthermore, activation of PAG GABAergic neurons or inhibition of glutamatergic neurons resulted in attenuation of scratching in both acute and chronic pruritis. Surprisingly, PAG GABAergic neurons, but not glutamatergic neurons, may encode the aversive component of itch. Thus, the PAG represents a neuromodulatory hub that regulates both the sensory and affective aspects of acute and chronic itch.
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Affiliation(s)
- Vijay K Samineni
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Washington University Pain Center, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
| | - Jose G Grajales-Reyes
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Washington University Pain Center, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Medical Scientist Training Program, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Neuroscience Program, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
| | - Saranya S Sundaram
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Washington University Pain Center, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
| | - Judy J Yoo
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
- Washington University Pain Center, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA
| | - Robert W Gereau
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA.
- Washington University Pain Center, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA.
- Department of Neuroscience, Department of Biomedical Engineering, Washington University School of Medicine, 660 S. Euclid Ave, Box 8054, St. Louis, MO, 63110, USA.
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Dong X, Dong X. Peripheral and Central Mechanisms of Itch. Neuron 2019; 98:482-494. [PMID: 29723501 DOI: 10.1016/j.neuron.2018.03.023] [Citation(s) in RCA: 222] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 03/12/2018] [Accepted: 03/15/2018] [Indexed: 12/15/2022]
Abstract
Itch is a unique sensory experience that is encoded by genetically distinguishable neurons both in the peripheral nervous system (PNS) and central nervous system (CNS) to elicit a characteristic behavioral response (scratching). Itch interacts with the other sensory modalities at multiple locations, from its initiation in a particular dermatome to its transmission to the brain where it is finally perceived. In this review, we summarize the current understanding of the molecular and neural mechanisms of itch by starting in the periphery, where itch is initiated, and discussing the circuits involved in itch processing in the CNS.
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Affiliation(s)
- Xintong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Sanders KM, Fast K, Yosipovitch G. Why we scratch: Function and dysfunction. Exp Dermatol 2019; 28:1482-1484. [DOI: 10.1111/exd.13977] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/17/2019] [Accepted: 05/21/2019] [Indexed: 01/20/2023]
Affiliation(s)
- Kristen M. Sanders
- Dr Phillip Frost Department of Dermatology and Cutaneous Surgery and Miami Itch Center, Miller School of Medicine University of Miami Miami Florida
| | - Katharine Fast
- Department of Allergy and Immunology California Pacific Medical Center San Francisco California
| | - Gil Yosipovitch
- Dr Phillip Frost Department of Dermatology and Cutaneous Surgery and Miami Itch Center, Miller School of Medicine University of Miami Miami Florida
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Su XY, Chen M, Yuan Y, Li Y, Guo SS, Luo HQ, Huang C, Sun W, Li Y, Zhu MX, Liu MG, Hu J, Xu TL. Central Processing of Itch in the Midbrain Reward Center. Neuron 2019; 102:858-872.e5. [PMID: 31000426 DOI: 10.1016/j.neuron.2019.03.030] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 12/28/2018] [Accepted: 03/19/2019] [Indexed: 10/27/2022]
Abstract
Itch is an aversive sensation that evokes a desire to scratch. Paradoxically, scratching the itch also produces a hedonic experience. The specific brain circuits processing these different aspects of itch, however, remain elusive. Here, we report that GABAergic (GABA) and dopaminergic (DA) neurons in the ventral tegmental area (VTA) are activated with different temporal patterns during acute and chronic itch. DA neuron activation lags behind GABA neurons and is dependent on scratching of the itchy site. Optogenetic manipulations of VTA GABA neurons rapidly modulated scratching behaviors through encoding itch-associated aversion. In contrast, optogenetic manipulations of VTA DA neurons revealed their roles in sustaining recurrent scratching episodes through signaling scratching-induced reward. A similar dichotomy exists for the role of VTA in chronic itch. These findings advance understanding of circuit mechanisms of the unstoppable itch-scratch cycles and shed important insights into chronic itch therapy.
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Affiliation(s)
- Xin-Yu Su
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ming Chen
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China
| | - Yuan Yuan
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ying Li
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Su-Shan Guo
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Huo-Qing Luo
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chen Huang
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wenzhi Sun
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Chinese Institute for Brain Research, Beijing 102206, China
| | - Yong Li
- Collaborative Innovation Center for Brain Science, Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai 201210, China
| | - Michael X Zhu
- Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Ming-Gang Liu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai 201210, China.
| | - Tian-Le Xu
- Collaborative Innovation Center for Brain Science, Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Shanghai Research Center for Brain Science and Brain-Inspired Intelligence, Shanghai 201210, China.
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Follansbee T, Akiyama T, Fujii M, Davoodi A, Nagamine M, Iodi Carstens M, Carstens E. Effects of pruritogens and algogens on rostral ventromedial medullary ON and OFF cells. J Neurophysiol 2018; 120:2156-2163. [PMID: 29947594 PMCID: PMC6295534 DOI: 10.1152/jn.00208.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/03/2018] [Accepted: 06/03/2018] [Indexed: 11/22/2022] Open
Abstract
Rostroventromedial medulla (RVM) ON and OFF cells are thought to facilitate and inhibit spinal nociceptive transmission, respectively. However, it is unknown how ON and OFF cells respond to pruritic stimuli or how they contribute to descending modulation of spinal itch signaling. In pentobarbital sodium-anesthetized mice, single-unit recordings were made in RVM from ON and OFF cells identified by their respective increase or decrease in firing that occurred just before nocifensive hindlimb withdrawal elicited by paw pinch. Of RVM ON cells, 75% (21/28) were excited by intradermal histamine, 50% (10/20) by intradermal chloroquine, and 75% (27/36) by intradermal capsaicin. Most chemically responsive units also responded to a scratch stimulus applied to the injected hindpaw. Few ON cells responded to intradermal injection of vehicle (saline: 5/32; Tween 2/17) but still responded to scratching. For OFF cells, intradermal histamine and scratching inhibited 32% (6/19) with no effect of histamine in the remainder. Intradermal chloroquine inhibited 44% (4/9) and intradermal capsaicin inhibited 61% (11/18) of OFF cells. Few OFF cells were affected by vehicles (Tween: 1 inhibited, 7 unaffected; saline: 3 excited, 1 inhibited, 8 unaffected). Both ON and OFF cells that responded to one chemical usually also responded to others, whereas units unresponsive to the first-tested chemical tended not to respond to others. These results indicate that ascending pruriceptive signals activate RVM ON cells and inhibit RVM OFF cells. These effects are considered to facilitate and disinhibit spinal pain transmission, respectively. It is currently not clear if spinal itch transmission is similarly modulated. NEW & NOTEWORTHY The rostroventromedial medulla (RVM) contains ON and OFF cells that are, respectively, excited and inhibited by noxious stimuli and have descending projections that facilitate and inhibit spinal nociceptive transmission. Most RVM ON cells were excited, and OFF cells inhibited, by intradermal injection of the pruritogens histamine and chloroquine, as well as the algogen capsaicin. These results indicate that itchy stimuli activate RVM neurons that presumably give rise to descending modulation of spinal itch transmission.
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Affiliation(s)
- T. Follansbee
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
- Center for Neuroscience, University of California, Davis, California
| | - T. Akiyama
- Department of Dermatology and Cutaneous Surgery, University of Miami School of Medicine, Miami, Florida
| | - M. Fujii
- Department of Pharmacology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - A. Davoodi
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - M. Nagamine
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - M. Iodi Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
| | - E. Carstens
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, California
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Ehling S, Butler A, Thi S, Ghashghaei HT, Bäumer W. To scratch an itch: Establishing a mouse model to determine active brain areas involved in acute histaminergic itch. IBRO Rep 2018; 5:67-73. [PMID: 30364768 PMCID: PMC6197726 DOI: 10.1016/j.ibror.2018.10.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/13/2018] [Indexed: 12/30/2022] Open
Abstract
The specific histamine H4 receptor agonist ST-1006 induces acute itch in mice. Histaminergic itch increases neuronal activity in the medial habenula. Selective H4R activation in the skin increases neuronal activity in the medial habenula.
Background Strategies to efficiently control itch require a deep understanding of the underlying mechanisms. Several areas in the brain involved in itch and scratching responses have been postulated, but the central mechanisms that drive pruritic responses are still unknown. Histamine is recognized as a major mediator of itch in humans, and has been the most frequently used stimulus as an experimental pruritogen for brain imaging of itch. Objective Histaminergic itch via histamine and the selective histamine H4 receptor (H4R) agonist, ST-1006, recruit brain nuclei through c-fos activation and activate specific areas in the brain. Methods An acute itch model was established in c-fos-EGFP transgenic mice using ST-1006 and histamine. Coronal brain sections were stained for c-fos immunoreactivity and the forebrain was mapped for density of c-fos + nuclei. Results Histamine and ST-1006 significantly increased scratching response in c-fos-EGFP mice compared to vehicle controls. Mapping c-fos immunostained brain sections revealed neuronal activity in the cortex, striatum, hypothalamus, thalamus, amygdala, and the midbrain. Conclusions Histaminergic itch and selective H4R activation significantly increased the density of c-fos + nuclei in the medial habenula (MHb). Thus, the MHb may be a new target to investigate and subsequently develop novel mechanism-based strategies to treat itch and possibly provide a locus for pharmacological control of pruritus.
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Affiliation(s)
- Sarah Ehling
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA.,Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Ashley Butler
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - Stephanie Thi
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - H Troy Ghashghaei
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA
| | - Wolfgang Bäumer
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, NC, USA.,Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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Dynamics and Functional Role of Dopaminergic Neurons in the Ventral Tegmental Area during Itch Processing. J Neurosci 2018; 38:9856-9869. [PMID: 30266741 DOI: 10.1523/jneurosci.1483-18.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/10/2018] [Accepted: 09/14/2018] [Indexed: 11/21/2022] Open
Abstract
Itchiness triggers a strong urge to engage in scratching behavior, which could lead to severe skin or tissue damage in patients with chronic itch. This process is dynamically modulated. However, the neural mechanisms underlying itch modulation remain largely unknown. Here, we report that dopaminergic (DA) neurons in the ventral tegmental area (VTA) play a critical role in modulating itch-induced scratching behavior. We found that the activity of VTA DA neurons was increased during pruritogen-induced scratching behavior in freely moving male mice. Consistently, individual VTA DA neurons mainly exhibited elevated neural activity during itch-induced scratching behavior as demonstrated by in vivo extracellular recording. In behavioral experiments, the transient suppression of VTA DA neurons with the optogenetic approach shortened the pruritogen-induced scratching train. Furthermore, the DA projection from the VTA to the lateral shell of the nucleus accumbens exhibited strong activation as measured with fiber photometry during itch-elicited scratching behavior. These results revealed the dynamic activity of VTA DA neurons during itch processing and demonstrated the modulatory role of the DA system in itch-induced scratching behavior.SIGNIFICANCE STATEMENT Itchiness is an unpleasant sensation that evokes a scratching response for relief. However, the neural mechanism underlying the modulation of itch-evoked scratching in the brain remains elusive. Here, by combining fiber photometry, extracellular recording, and optogenetic manipulation, we show that the dopaminergic neurons in the ventral tegmental area play a modulatory role in itch-evoked scratching behavior. These results reveal a potential target for suppressing excessive scratching responses in patients with chronic itch.
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Abstract
Chronic, persistent itch is a devastating symptom that causes much suffering. In recent years, there has been great progress made in understanding the molecules, cells, and circuits underlying itch sensation. Once thought to be carried by pain-sensing neurons, itch is now believed to be capable of being transmitted by dedicated sensory labeled lines. Members of the Mas-related G protein-coupled receptor (Mrgpr) family demarcate an itch-specific labeled line in the peripheral nervous system. In the spinal cord, the expression of other proteins identifies additional populations of itch-dedicated sensory neurons. However, as evidence for labeled-line coding has mounted, studies promoting alternative itch-coding strategies have emerged, complicating our understanding of the neural basis of itch. In this review, we cover the molecules, cells, and circuits related to understanding the neural basis of itch, with a focus on the role of Mrgprs in mediating itch sensation.
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Affiliation(s)
- James Meixiong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA; ,
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and the Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA; , .,Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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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: 12] [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 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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Abstract
Atopic dermatitis (AD) is the most common itchy dermatosis that affects millions of children and adults worldwide. Chronic itch in this condition has significant impact on measures of quality of life, such as sleep. Treating itch in AD has been challenging for decades, but new drugs have emerged in the last year with significant anti-pruritic effect. The optimal treatment regimen for atopic itch addresses barrier dysfunction, inflammation, neural hypersensitivity, and the itch-scratch cycle. Topical moisturizers remain the foundation of treatment and should be used by all patients with AD-associated pruritus. Step-wise therapy, from topical anti-inflammatory creams to systemic monoclonal antibodies and immunosuppressants, is recommended. There are multiple adjuvant therapies that can be used, especially to target itch in the setting of minimal skin inflammation. Finally, patient education, sleep management, and stress relief are important components to optimize outcomes. This review assesses the latest advances and treatment recommendations for pruritus in AD. Finally, suggested therapeutic ladders and emerging treatments are discussed.
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Andersen HH, Akiyama T, Nattkemper LA, van Laarhoven A, Elberling J, Yosipovitch G, Arendt-Nielsen L. Alloknesis and hyperknesis—mechanisms, assessment methodology, and clinical implications of itch sensitization. Pain 2018; 159:1185-1197. [DOI: 10.1097/j.pain.0000000000001220] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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40
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Cockburn A, Smith M, Rusbridge C, Fowler C, Paul ES, Murrell JC, Blackwell EJ, Casey RA, Whay HR, Mendl M. Evidence of negative affective state in Cavalier King Charles Spaniels with syringomyelia. Appl Anim Behav Sci 2018. [DOI: 10.1016/j.applanim.2017.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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41
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Nocebo-induced modulation of cerebral itch processing - An fMRI study. Neuroimage 2017; 166:209-218. [PMID: 29107770 DOI: 10.1016/j.neuroimage.2017.10.056] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/12/2017] [Accepted: 10/25/2017] [Indexed: 12/29/2022] Open
Abstract
It has been shown repeatedly that perceiving itch-related pictures or listening to a lecture on itch can enhance itch sensation and scratching behaviour (Niemeier and Gieler, 2000; Holle et al., 2012; Lloyd et al., 2013), indicating that itch is strongly influenced by expectations. Using fMRI, we investigated the neural correlates of the itch-related nocebo effect in healthy male and female human subjects. Itch sensation on the left forearm was induced by cutaneous histamine application and thermally modulated, with cooling leading to higher itch. Nocebo-induced aggravation of histaminergic itch was achieved by ostensibly treating volunteers with "transcutaneous electrical nerve stimulation (TENS)" about which subjects were instructed that it would increase itch. During a conditioning phase subjects indeed experienced stronger itch due to slightly altered cooling and histamine concentrations, but attributed it to the alleged "TENS stimulation". Importantly, in the subsequent test phase where no "TENS" or electrical stimulation was applied, volunteers significantly reported stronger itch during the nocebo as compared to the control condition. Comparing BOLD responses during nocebo in contrast to control, we observed increased activity in contralateral (right) rolandic operculum. Opercular involvement was repeatedly reported in studies related to the expectation of stimulus intensification and might thus represent an early area integrating expectation information with somatosensory information. Finally, functional coupling between the insula and the periaqueductal gray (PAG) was enhanced specifically in the nocebo condition. This cortex-PAG interaction indicates that context-dependent top-down modulation during itch might represent a shared mechanism with other modalities such as pain.
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42
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Sun S, Xu Q, Guo C, Guan Y, Liu Q, Dong X. Leaky Gate Model: Intensity-Dependent Coding of Pain and Itch in the Spinal Cord. Neuron 2017; 93:840-853.e5. [PMID: 28231466 DOI: 10.1016/j.neuron.2017.01.012] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 12/06/2016] [Accepted: 01/13/2017] [Indexed: 01/01/2023]
Abstract
Coding of itch versus pain has been heatedly debated for decades. However, the current coding theories (labeled line, intensity, and selectivity theory) cannot accommodate all experimental observations. Here we identified a subset of spinal interneurons, labeled by gastrin-releasing peptide (Grp), that receive direct synaptic input from both pain and itch primary sensory neurons. When activated, these Grp+ neurons generated rarely seen, simultaneous robust pain and itch responses that were intensity dependent. Accordingly, we propose a "leaky gate" model in which Grp+ neurons transmit both itch and weak pain signals; however, upon strong painful stimuli, the recruitment of endogenous opioids works to close this gate, reducing overwhelming pain generated by parallel pathways. Consistent with our model, loss of these Grp+ neurons increased pain responses while itch was decreased. Our new model serves as an example of non-monotonic coding in the spinal cord and better explains observations in human psychophysical studies.
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Affiliation(s)
- Shuohao Sun
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qian Xu
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Changxiong Guo
- Department of Anesthesiology and the Center for the Study of Itch, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Qin Liu
- Department of Anesthesiology and the Center for the Study of Itch, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, 63110, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience and Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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43
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Liu BW, Li ZX, He ZG, Liu C, Xiong J, Xiang HB. Altered expression of target genes of spinal cord in different itch models compared with capsaicin assessed by RT-qPCR validation. Oncotarget 2017; 8:74423-74433. [PMID: 29088797 PMCID: PMC5650352 DOI: 10.18632/oncotarget.20148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 05/23/2017] [Indexed: 11/25/2022] Open
Abstract
Spinal cord plays a central role in the development and progression of pathogenesis of obstinate pruritus. In the current study, four groups of adult male C57Bl/6 mice were investigated; one group treated with saline, while the other groups intradermally injected with compound 48/80, histamine, α-Me-5-HT and capsaicin (algogenic substance), respectively. The intradermal microinjection of pruritic and algogenic compound resulted in a dramatic increase in the itch/algogenic behavior. Analysis of the microarray data showed that 15 genes in spinal cord (C5-C8) were differentially expressed between control group and 48/80 group, in which 9 genes were up-regulated and 6 genes were down-regulated. Furthermore, the results of RT-qPCR validation studies in C5-C8 spinal cord revealed that the 9 mRNA (Sgk1, Bag4, Fos, Ehd2, Edn3, Wdfy, Corin, 4921511E18Rik and 4930423020Rik) showed very different patterns for these different drugs, especially when comparing α-Me-5-HT and capsaicin. In three itch models, Fos and Ehd2 were up-regulated whereas Corin, 4921511E18Rik and 4930423020Rik were down-regulated. Furthermore, Corin and 4930423020Rik were down-regulated in itch model group compared to capsaicin group. Thus the application of microarray technique, coupled with RT-qPCR validation, further explain the mechanism behind itching evoked by pruritic compounds. It can contribute to our understanding of pharmacological methods for prevention or treatment of obstinate pruritus.
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Affiliation(s)
- Bao-Wen Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi-Xiao Li
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi-Gang He
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Cheng Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jun Xiong
- Hepatobiliary Surgery Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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44
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Green D, Dong X. The cell biology of acute itch. J Cell Biol 2017; 213:155-61. [PMID: 27114499 PMCID: PMC4862869 DOI: 10.1083/jcb.201603042] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 04/05/2016] [Indexed: 01/22/2023] Open
Abstract
Itch, the irritation we feel and the relief that comes from scratching, is an evolutionary warning system and defense against harmful environmental agents. Although once considered a subtype of pain, itch is now recognized as a unique sense, with its own distinct physiology and cell receptors. Here, we discuss recent advances in our understanding of itch and the molecular players that mediate this sensory modality.
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Affiliation(s)
- Dustin Green
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD 21205 Howard Hughes Medical Institute, Johns Hopkins University, School of Medicine, Baltimore, MD 21205
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45
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Mueller SM, Hogg S, Mueller JM, McKie S, Itin P, Reinhardt J, Griffiths CE, Kleyn CE. Functional magnetic resonance imaging in dermatology: The skin, the brain and the invisible. Exp Dermatol 2017; 26:845-853. [DOI: 10.1111/exd.13305] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/17/2017] [Indexed: 01/05/2023]
Affiliation(s)
- Simon M. Mueller
- Department of Dermatology; University Hospital Basel; Basel Switzerland
- Dermatology Centre; The Manchester Academic Health Science Centre; The University of Manchester; Manchester UK
| | - Samuel Hogg
- Department of Dermatology; University Hospital Basel; Basel Switzerland
| | - Jannis M. Mueller
- Department of Neurology; Kantonsspital Muensterlingen; Muensterlingen Switzerland
| | - Shane McKie
- Neuroscience and Psychiatry Unit; The Manchester Academic Health Science Centre; The University of Manchester; Manchester UK
| | - Peter Itin
- Dermatology Centre; The Manchester Academic Health Science Centre; The University of Manchester; Manchester UK
| | - Julia Reinhardt
- Division of Diagnostic & Interventional Neuroradiology; University Hospital Basel; Basel Switzerland
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46
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Toll-like receptor 4 contributes to chronic itch, alloknesis, and spinal astrocyte activation in male mice. Pain 2017; 157:806-817. [PMID: 26645545 DOI: 10.1097/j.pain.0000000000000439] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Increasing evidence suggests that Toll-like receptor 4 (TLR4) contributes importantly to spinal cord glial activation and chronic pain sensitization; however, its unique role in acute and chronic itch is unclear. In this study, we investigated the involvement of TLR4 in acute and chronic itch models in male mice using both transgenic and pharmacological approaches. Tlr4 mice exhibited normal acute itch induced by compound 48/80 and chloroquine, but these mice showed substantial reductions in scratching in chronic itch models of dry skin, induced by acetone and diethylether followed by water (AEW), contact dermatitis, and allergic contact dermatitis on the neck. Intrathecal (spinal) inhibition of TLR4 with lipopolysaccharide Rhodobacter sphaeroides did not affect acute itch but suppressed AEW-induced chronic itch. Compound 48/80 and AEW also produced robust alloknesis, a touch-elicited itch in wild-type mice, which was suppressed by intrathecal lipopolysaccharide R sphaeroides and Tlr4 deletion. Acetone and diethylether followed by water induced persistent upregulation of Tlr4 mRNA and increased TLR4 expression in GFAP-expressing astrocytes in spinal cord dorsal horn. Acetone and diethylether followed by water also induced TLR4-dependent astrogliosis (GFAP upregulation) in spinal cord. Intrathecal injection of astroglial inhibitor L-α-aminoadipate reduced AEW-induced chronic itch and alloknesis without affecting acute itch. Spinal TLR4 was also necessary for AEW-induced chronic itch in the cheek model. Interestingly, scratching plays an essential role in spinal astrogliosis because AEW-induced astrogliosis was abrogated by putting Elizabethan collars on the neck to prevent scratching the itchy skin. Our findings suggest that spinal TLR4 signaling is important for spinal astrocyte activation and astrogliosis that may underlie alloknesis and chronic itch.
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47
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Tian B, Wang XL, Huang Y, Chen LH, Cheng RX, Zhou FM, Guo R, Li JC, Liu T. Peripheral and spinal 5-HT receptors participate in cholestatic itch and antinociception induced by bile duct ligation in rats. Sci Rep 2016; 6:36286. [PMID: 27824106 PMCID: PMC5099756 DOI: 10.1038/srep36286] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022] Open
Abstract
Although 5-HT has been implicated in cholestatic itch and antinociception, two common phenomena in patients with cholestatic disease, the roles of 5-HT receptor subtypes are unclear. Herein, we investigated the roles of 5-HT receptors in itch and antinociception associated with cholestasis, which was induced by common bile duct ligation (BDL) in rats. 5-HT-induced enhanced scratching and antinociception to mechanical and heat stimuli were demonstrated in BDL rats. 5-HT level in the skin and spinal cord was significantly increased in BDL rats. Quantitative RT-PCR analysis showed 5-HT1B, 5-HT1D, 5-HT2A, 5-HT3A, 5-HT5B, 5-HT6, and 5-HT7 were up-regulated in peripheral nervous system and 5-HT1A, 5-HT1F, 5-HT2B, and 5-HT3A were down-regulated in the spinal cord of BDL rats. Intradermal 5-HT2, 5-HT3, and 5-HT7 receptor agonists induced scratching in BDL rats, whereas 5-HT3 agonist did not induce scratching in sham rats. 5-HT1A, 5-HT2, 5-HT3, and 5-HT7 agonists or antagonists suppressed itch in BDL rats. 5-HT1A agonist attenuated, but 5-HT1A antagonist enhanced antinociception in BDL rats. 5-HT2 and 5-HT3 agonists or antagonists attenuated antinociception in BDL rats. Our data suggested peripheral and central 5-HT system dynamically participated in itch and antinociception under cholestasis condition and targeting 5-HT receptors may be an effective treatment for cholestatic itch.
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Affiliation(s)
- Bin Tian
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Xue-Long Wang
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Ya Huang
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Li-Hua Chen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, School of Public Health, Soochow University, Suzhou, 215123, China
| | - Ruo-Xiao Cheng
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Feng-Ming Zhou
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
| | - Ran Guo
- Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, 215006, China
| | - Jun-Cheng Li
- Department of General Surgery, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China
| | - Tong Liu
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou, Jiangsu, 215123, China
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48
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Zhou FM, Cheng RX, Wang S, Huang Y, Gao YJ, Zhou Y, Liu TT, Wang XL, Chen LH, Liu T. Antioxidants Attenuate Acute and Chronic Itch: Peripheral and Central Mechanisms of Oxidative Stress in Pruritus. Neurosci Bull 2016; 33:423-435. [PMID: 27783328 DOI: 10.1007/s12264-016-0076-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/27/2016] [Indexed: 12/12/2022] Open
Abstract
Itch (pruritus) is one of the most disabling syndromes in patients suffering from skin, liver, or kidney diseases. Our previous study highlighted a key role of oxidative stress in acute itch. Here, we evaluated the effects of antioxidants in mouse models of acute and chronic itch and explored the potential mechanisms. The effects of systemic administration of the antioxidants N-acetyl-L-cysteine (NAC) and N-tert-butyl-α-phenylnitrone (PBN) were determined by behavioral tests in mouse models of acute itch induced by compound 48/80 or chloroquine, and chronic itch by treatment with a mixture of acetone-diethyl-ether-water. We found that systemic administration of NAC or PBN significantly alleviated compound 48/80- and chloroquine-induced acute itch in a dose-dependent manner, attenuated dry skin-induced chronic itch, and suppressed oxidative stress in the affected skin. Antioxidants significantly decreased the accumulation of intracellular reactive oxygen species directly induced by compound 48/80 and chloroquine in the cultured dorsal root ganglia-derived cell line ND7-23. Finally, the antioxidants remarkably inhibited the compound 48/80-induced phosphorylation of extracellular signal-regulated kinase in the spinal cord. These results indicated that oxidative stress plays a critical role in acute and chronic itch in the periphery and spinal cord and antioxidant treatment may be a promising strategy for anti-itch therapy.
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Affiliation(s)
- Feng-Ming Zhou
- Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China.,Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Ruo-Xiao Cheng
- Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China.,Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Shuai Wang
- Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China.,Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, 215123, China
| | - Ya Huang
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Yong-Jing Gao
- Institute of Nautical Medicine, Nantong University, Nantong, 226001, China
| | - Yan Zhou
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Teng-Teng Liu
- Institute of Neuroscience, Soochow University, Suzhou, 215123, China
| | - Xue-Long Wang
- Beijing Electric Power Hospital, Beijing, 100073, China
| | - Li-Hua Chen
- Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, 215123, China.
| | - Tong Liu
- Department of Neurology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China. .,Institute of Neuroscience, Soochow University, Suzhou, 215123, China.
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Abstract
This chapter summarizes recent findings regarding the central transmission of acute and chronic itch. Itch is transduced by cutaneous pruriceptors that transmit signals to neurons in the superficial spinal cord. Spinal itch-signaling circuits utilize several neuropeptides whose receptors represent novel targets to block itch transmission. Itch is relieved by scratching, which activates spinal interneurons to inhibit itch-transmitting neurons. Spinal itch transmission is also thought to be modulated by descending pathways. Itch is transmitted rostrally via ascending pathways to activate a variety of brain regions involved in sensory discrimination of affective and motor responses to itch. The pathophysiological mechanisms of chronic itch are poorly understood but likely involve sensitization of itch-signaling pathways and/or dysfunction of itch-inhibitory circuits. Improved understanding of central itch mechanisms has identified a number of novel targets for the development of antipruritic treatment strategies.
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50
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Kuraishi Y. Methods for preclinical assessment of antipruritic agents and itch mechanisms independent of mast-cell histamine. Biol Pharm Bull 2016; 38:635-44. [PMID: 25947907 DOI: 10.1248/bpb.b15-00090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Itch is a sensation that provokes a desire to scratch. Mast-cell histamine was thought to be a key itch mediator. However, histamine and mast-cell degranulation were reported not to elicit scratching in animals. It was difficult to investigate the pathophysiology of itching and to evaluate the antipruritic efficacy of chemical agents in the early 1990 s. We showed that hind-paw scratching and biting were elicited by stimulation with pruritogenic agents in mice. Those results demonstrated for the first time that cutaneous itching could be evaluated behaviorally in animals. We established various animal models of pathological itch of the skin (dry skin, mosquito allergy, surfactant-induced pruritus, and herpes zoster) and mucus membranes (pollen allergy). Mast-cell histamine did not play a key role in itching in any animal model examined except for the pollen allergy model. Histamine is not an exclusive itch mediator of mast cells; tryptase and leukotriene B4 released from mast cells also act as itch mediators. Epidermal keratinocytes release several itch mediators, such as leukotriene B4, sphingosylphosphorylcholine, thromboxane A2, nociceptin, nitric oxide, and histamine, which may play important roles in pathological itching. Appropriate animal models of pathological itching are needed for pharmacological evaluation of the antipruritic efficacy of chemical agents.
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Affiliation(s)
- Yasushi Kuraishi
- Laboratory of Applied Pharmacology, Graduate School of Medicine and
Pharmaceutical Sciences, University of Toyama
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