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Wang TT, Li ZY, Hu DD, Xu XY, Song NJ, Li GQ, Zhang L. Spinal histamine H4 receptor mediates chronic pruritus via p-ERK in acetone-ether-water (AEW)-induced dry skin mice. Exp Dermatol 2024; 33:e15128. [PMID: 38973249 DOI: 10.1111/exd.15128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 05/24/2024] [Accepted: 06/14/2024] [Indexed: 07/09/2024]
Abstract
Dry skin is common to many pruritic diseases and is difficult to improve with oral traditional antihistamines. Recently, increasing evidence indicated that histamine H4 receptor (H4R) plays an important role in the occurrence and development of pruritus. Extracellular signal-regulated kinase (ERK) phosphorylation activation in the spinal cord mediates histamine-induced acute and choric itch. However, whether the histamine H4 receptor regulates ERK activation in the dry skin itch remains unclear. In the study, we explore the role of the histamine H4 receptor and p-ERK in the spinal cord in a dry skin mouse model induced by acetone-ether-water (AEW). q-PCR, Western blot, pharmacology and immunofluorescence were applied in the study. We established a dry skin itch model by repeated application of AEW on the nape of neck in mice. The AEW mice showed typically dry skin histological change and persistent spontaneous scratching behaviour. Histamine H4 receptor, instead of histamine H1 receptor, mediated spontaneous scratching behaviour in AEW mice. Moreover, c-Fos and p-ERK expression in the spinal cord neurons were increased and co-labelled with GRPR-positive neurons in AEW mice. Furthermore, H4R agonist 4-methyhistamine dihydrochloride (4-MH)induced itch. Both 4-MH-induced itch and the spontaneous itch in AEW mice were blocked by p-ERK inhibitor U0126. Finally, intrathecal H4R receptor antagonist JNJ7777120 inhibited spinal p-ERK expression in AEW mice. Our results indicated that spinal H4R mediates itch via ERK activation in the AEW-induced dry skin mice.
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Affiliation(s)
- Ting-Ting Wang
- Department of Neurology and Neurological Rehabilitation, Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), Tongji University School of Medicine, Shanghai, China
- Laboratory of Sensory Neurobiology, Department of Human Anatomy, Histology and Embryology, Tongji University School of Medicine, Shanghai, China
| | - Zi-Yang Li
- Department of Neurology and Neurological Rehabilitation, Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), Tongji University School of Medicine, Shanghai, China
- Laboratory of Sensory Neurobiology, Department of Human Anatomy, Histology and Embryology, Tongji University School of Medicine, Shanghai, China
| | - Dan-Dan Hu
- Department of Neurology and Neurological Rehabilitation, Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), Tongji University School of Medicine, Shanghai, China
- Laboratory of Sensory Neurobiology, Department of Human Anatomy, Histology and Embryology, Tongji University School of Medicine, Shanghai, China
| | - Xian-Yun Xu
- Laboratory of Sensory Neurobiology, Department of Human Anatomy, Histology and Embryology, Tongji University School of Medicine, Shanghai, China
| | - Ning-Jing Song
- Department of Dermatology, Tongren Hospital Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Gang-Qiang Li
- Department of Pathology, Naval Medical Center, Naval Medical University, Shanghai, China
| | - Ling Zhang
- Department of Neurology and Neurological Rehabilitation, Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), Tongji University School of Medicine, Shanghai, China
- Laboratory of Sensory Neurobiology, Department of Human Anatomy, Histology and Embryology, Tongji University School of Medicine, Shanghai, China
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Pușcașu C, Negreș S, Zbârcea CE, Ungurianu A, Ștefănescu E, Blebea NM, Chiriță C. Evaluating the Antihyperalgesic Potential of Sildenafil-Metformin Combination and Its Impact on Biochemical Markers in Alloxan-Induced Diabetic Neuropathy in Rats. Pharmaceuticals (Basel) 2024; 17:783. [PMID: 38931450 PMCID: PMC11206800 DOI: 10.3390/ph17060783] [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: 05/10/2024] [Revised: 06/03/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
(1) Background: Globally, about 600 million people are afflicted with diabetes, and one of its most prevalent complications is neuropathy, a debilitating condition. At the present time, the exploration of novel therapies for alleviating diabetic-neuropathy-associated pain is genuinely captivating, considering that current therapeutic options are characterized by poor efficacy and significant risk of side effects. In the current research, we evaluated the antihyperalgesic effect the sildenafil (phosphodiesterase-5 inhibitor)-metformin (antihyperglycemic agent) combination and its impact on biochemical markers in alloxan-induced diabetic neuropathy in rats. (2) Methods: This study involved a cohort of 70 diabetic rats and 10 non-diabetic rats. Diabetic neuropathy was induced by a single dose of 130 mg/kg alloxan. The rats were submitted to thermal stimulus test using a hot-cold plate and to tactile stimulus test using von Frey filaments. Moreover, at the end of the experiment, the animals were sacrificed and their brains and livers were collected to investigate the impact of this combination on TNF-α, IL-6, nitrites and thiols levels. (3) Results: The results demonstrated that all sildenafil-metformin combinations decreased the pain sensitivity in the von Frey test, hot plate test and cold plate test. Furthermore, alterations in nitrites and thiols concentrations and pro-inflammatory cytokines (specifically TNF-α and IL-6) were noted following a 15-day regimen of various sildenafil-metformin combinations. (4) Conclusions: The combination of sildenafil and metformin has a synergistic effect on alleviating pain in alloxan-induced diabetic neuropathy rats. Additionally, the combination effectively decreased inflammation, inhibited the rise in NOS activity, and provided protection against glutathione depletion.
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Affiliation(s)
- Ciprian Pușcașu
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
| | - Simona Negreș
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
| | - Cristina Elena Zbârcea
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
| | - Anca Ungurianu
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
| | - Emil Ștefănescu
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
| | - Nicoleta Mirela Blebea
- Faculty of Pharmacy, “Ovidius” University of Constanța, Căpitan Aviator Al. Şerbănescu 6, 900470 Constanța, Romania;
| | - Cornel Chiriță
- Faculty of Pharmacy, “Carol Davila” University of Medicine and Pharmacy, Traian Vuia 6, 020956 Bucharest, Romania; (C.P.); (S.N.); (A.U.); (E.Ș.); (C.C.)
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3
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Abstract
Itch arising from glabrous skin (palms and soles) has attracted limited attention within the field due to the lack of methodology. This is despite glabrous itch arising from many medical conditions such as plantar and palmar psoriasis, dyshidrosis, and cholestasis. Therefore, we developed a mouse glabrous skin behavioral assay to investigate the contribution of three previously identified pruriceptive neurons in glabrous skin itch. Our results show that MrgprA3+ and MrgprD+ neurons, although key mediators for hairy skin itch, do not play important roles in glabrous skin itch, demonstrating a mechanistic difference in itch sensation between hairy and glabrous skin. We found that MrgprC11+ neurons are the major mediators for glabrous skin itch. Activation of MrgprC11+ neurons induced glabrous skin itch, while ablation of MrgprC11+ neurons reduced both acute and chronic glabrous skin itch. Our study provides insights into the mechanisms of itch and opens up new avenues for future glabrous skin itch research.
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Li HP, Wang XY, Chen C, Li JJ, Yu C, Lin LX, Yu ZE, Jin ZY, Zhu H, Xiang HC, Hu XF, Cao J, Jing XH, Li M. 100 Hz Electroacupuncture Alleviated Chronic Itch and GRPR Expression Through Activation of Kappa Opioid Receptors in Spinal Dorsal Horn. Front Neurosci 2021; 15:625471. [PMID: 33664646 PMCID: PMC7921323 DOI: 10.3389/fnins.2021.625471] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 01/20/2021] [Indexed: 11/19/2022] Open
Abstract
Background Clinical studies have shown that electroacupuncture (EA) alleviates chronic itch. Gastrin-releasing peptide receptor (GRPR) and dynorphin (DYN) in the spinal dorsal horn positively or negatively regulate itch, respectively. However, which frequency of EA is effective on relieving chronic itch and reducing the expression of GRPR, whether DYN-A in the spinal cord is involved in the underlying mechanism of the antipruritus effect of EA remains unknown. Methods The mixture of acetone and diethyl ether (1:1) [designated as AEW (acetone/diethyl ether and water) treatment] was used to induce the dry skin model of chronic itch. EA was applied to Quchi (LI11) and Hegu (LI4). Western blot was used to detect the expression of GRPR and DYN-A. Immunofluorescence was used to detect the expression of DYN-A. Results The AEW administration induced remarkable spontaneous scratching, enhanced the expression of GRPR, and reduced the expression of DYN-A. Compared with the sham EA, 2 Hz EA, or 15 Hz EA group, 100 Hz EA was the most effective frequency for relieving chronic itch, reducing the expression of GRPR, and increasing the expression of DYN-A in the cervical dorsal horn. Furthermore, intraperitoneal injection of kappa opioid receptors (KORs) antagonist nor-Binaltorphimine dihydrochloride (nor-BNI) significantly reversed the effect of 100 Hz EA on the inhibition of both itching behavior and GRPR expression. Conclusion EA at 100 Hz is the most effective frequency that inhibits chronic itch and GRPR expression through activation of KORs in the spinal dorsal horn, which can effectively guide the clinical treatment and improve the antipruritic effect of acupuncture.
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Affiliation(s)
- Hong-Ping Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiao-Yu Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Chao Chen
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing-Jing Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chi Yu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Xue Lin
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zi-E Yu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhi-Yuan Jin
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - He Zhu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Chun Xiang
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xue-Fei Hu
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Cao
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiang-Hong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Man Li
- Department of Neurobiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Kopruszinski CM, dos Reis RC, Rae GA, Chichorro JG. Blockade of peripheral endothelin receptors abolishes heat hyperalgesia and spontaneous nociceptive behavior in a rat model of facial cancer. Arch Oral Biol 2019; 97:231-237. [DOI: 10.1016/j.archoralbio.2018.10.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 10/30/2018] [Accepted: 10/31/2018] [Indexed: 12/27/2022]
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Palkar R, Ongun S, Catich E, Li N, Borad N, Sarkisian A, McKemy DD. Cooling Relief of Acute and Chronic Itch Requires TRPM8 Channels and Neurons. J Invest Dermatol 2017; 138:1391-1399. [PMID: 29288650 DOI: 10.1016/j.jid.2017.12.025] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 12/08/2017] [Accepted: 12/20/2017] [Indexed: 12/15/2022]
Abstract
Cooling or the application of mentholated liniments to the skin has been used to treat itch for centuries, yet remarkably little is known about how counter-stimuli such as these induce itch relief. Indeed, there is no clear consensus in the scientific literature as to whether or not cooling does in fact block the transduction of itch signals or if it is simply a placebo effect. This gap in our understanding led us to hypothesize that cooling is antipruritic and, like cooling analgesia, requires function of the cold-gated ion channel TRPM8, a receptor for menthol expressed on peripheral afferent nerve endings. Using a combination of pharmacologic, genetic, and mouse behavioral assays, we find that cooling inhibits both histaminergic and non-histaminergic itch pathways, and that inhibition of itch by cooling requires TRPM8 channels or intact and functional TRPM8-expressing afferent neurons. The cold mimetic menthol is also effective in ameliorating itch in a TRPM8-dependent manner. Moreover, we find that chronic itch can be ameliorated by cooling, demonstrating that this counter-stimulus activates a specific neural circuit that leads to broad itch relief and a potential cellular mechanism for treatment of chronic itch.
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Affiliation(s)
- Radhika Palkar
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California; Neuroscience Graduate Program, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - Serra Ongun
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California; Molecular and Computational Biology Graduate Program, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - Edward Catich
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California; Neuroscience Graduate Program, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - Natalie Li
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - Neil Borad
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - Angela Sarkisian
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California
| | - David D McKemy
- Neurobiology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California; Molecular and Computational Biology Graduate Program, Department of Biological Sciences, University of Southern California, Los Angeles, California; Neuroscience Graduate Program, Department of Biological Sciences, University of Southern California, Los Angeles, California.
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7
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Kittaka H, Uchida K, Fukuta N, Tominaga M. Lysophosphatidic acid-induced itch is mediated by signalling of LPA 5 receptor, phospholipase D and TRPA1/TRPV1. J Physiol 2017; 595:2681-2698. [PMID: 28176353 DOI: 10.1113/jp273961] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 01/31/2017] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Lysophosphatidic acid (LPA) is an itch mediator, but not a pain mediator by a cheek injection model. Dorsal root ganglion neurons directly respond to LPA depending on transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1). LPA-induced itch-related behaviours are decreased in TRPA1-knockout (KO), TRPV1KO or TRPA1TRPV1 double KO mice. TRPA1 and TRPV1 channels are activated by intracellular LPA, but not by extracellular LPA following LPA5 receptor activation with an activity of Ca2+ -independent phospholipase A2 and phospholipase D. Intracellular LPA interaction sites of TRPA1 are KK672-673 and KR977-978 (K: lysine, R: arginine). ABSTRACT Intractable and continuous itch sensations often accompany diseases such as atopic dermatitis, neurogenic lesions, uremia and cholestasis. Lysophosphatidic acid (LPA) is an itch mediator found in cholestatic itch patients and it induces acute itch and pain in experimental rodent models. However, the molecular mechanism by which LPA activates peripheral sensory neurons remains unknown. In this study, we used a cheek injection method in mice to reveal that LPA induced itch-related behaviours but not pain-related behaviours. The LPA-induced itch behaviour and cellular effects were dependent on transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1), which are important for itch signal transduction. We also found that, among the six LPA receptors, the LPA5 receptor had the greatest involvement in itching. Furthermore, we demonstrated that phospholipase D (PLD) plays a critical role downstream of LPA5 and that LPA directly and intracellularly activates TRPA1 and TRPV1. These results suggest a unique mechanism by which cytoplasmic LPA produced de novo could activate TRPA1 and TRPV1. We conclude that LPA-induced itch is mediated by LPA5 , PLD, TRPA1 and TRPV1 signalling, and thus targeting TRPA1, TRPV1 or PLD could be effective for cholestatic itch interventions.
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Affiliation(s)
- Hiroki Kittaka
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
| | - Kunitoshi Uchida
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan.,Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, 814-0193, Japan
| | - Naomi Fukuta
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
| | - Makoto Tominaga
- Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki, 444-8787, Japan.,Department of Physiological Sciences, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, 444-8787, Japan.,Institute for Environmental and Gender-Specific Medicine, Juntendo University, Urayasu, 279-0021, Japan
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Hoeck EA, Marker JB, Gazerani P, H. Andersen H, Arendt-Nielsen L. Preclinical and human surrogate models of itch. Exp Dermatol 2016; 25:750-7. [DOI: 10.1111/exd.13078] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Emil A. Hoeck
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Jens B. Marker
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Parisa Gazerani
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Hjalte H. Andersen
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
| | - Lars Arendt-Nielsen
- SMI; Department of Health Science and Technology; Faculty of Medicine; Aalborg University; Aalborg E Denmark
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9
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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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10
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Abstract
Itch is a unique sensation associated with the scratch reflex. Although the scratch reflex plays a protective role in daily life by removing irritants, chronic itch remains a clinical challenge. Despite urgent clinical need, itch has received relatively little research attention and its mechanisms have remained poorly understood until recently. The goal of the present review is to summarize our current understanding of the mechanisms of acute as well as chronic itch and classifications of the primary itch populations in relationship to transient receptor potential (Trp) channels, which play pivotal roles in multiple somatosensations. The convergent involvement of Trp channels in diverse itch signaling pathways suggests that Trp channels may serve as promising targets for chronic itch treatments.
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Affiliation(s)
- Shuohao Sun
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, 21205, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, 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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11
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Increased ZAP70 Is Involved in Dry Skin Pruritus in Aged Mice. BIOMED RESEARCH INTERNATIONAL 2016; 2016:6029538. [PMID: 27195291 PMCID: PMC4852331 DOI: 10.1155/2016/6029538] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/26/2016] [Accepted: 04/03/2016] [Indexed: 11/26/2022]
Abstract
Dry skin pruritus is common in the elderly. Recent reports show that T-cell signal path is involved in dry skin pruritus. Zeta-chain-associated protein kinase 70 (ZAP70), as a T-cell receptor, may induce interleukin 2 (IL-2) secretion and promote nerve growth factor (NGF) secretion in skin. This study aimed to detect the alteration of ZAP70 in a mice model with dry skin pruritus. The C57BL mice with 5 months and 22 months were used as experimental animal. Following a 5-day period of treatment of back with a mixture of acetone-diethyl-ether-water (AEW), mice exhibited a significant increase in spontaneous scratching behavior directed to the treated back compared to control animals in which back was similarly treated with water only (W). After AEW process, spontaneous scratching in 22-month AEW mice was increased compared to 5-month AEW mice. Western blot and real-time quantitative PCR data analysis showed that ZAP70 expression was significantly increased in 22-month AEW mice compared with 5-month AEW mice. ELISA data showed that secretions of IL-2 and NGF in 22-month AEW mice were higher than 5-month AEW mice. Our results indicate that increased ZAP70 is involved in dry skin in elderly pruritus. Increased secretion of IL-2 and NGF may induce dry skin itch.
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12
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GABAA Receptors in the Central Nucleus of the Amygdala Are Involved in Pain- and Itch-Related Responses. THE JOURNAL OF PAIN 2016; 17:181-9. [DOI: 10.1016/j.jpain.2015.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/09/2015] [Accepted: 10/17/2015] [Indexed: 11/20/2022]
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13
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Schüttenhelm BN, Duraku LS, Dijkstra JF, Walbeehm ET, Holstege JC. Differential Changes in the Peptidergic and the Non-Peptidergic Skin Innervation in Rat Models for Inflammation, Dry Skin Itch, and Dermatitis. J Invest Dermatol 2015; 135:2049-2057. [PMID: 25848979 DOI: 10.1038/jid.2015.137] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 11/25/2014] [Accepted: 12/11/2014] [Indexed: 01/07/2023]
Abstract
Skin innervation is a dynamic process that may lead to changes in nerve fiber density during pathological conditions. We have investigated changes in epidermal nerve fiber density in three different rat models that selectively produce chronic itch (the dry skin model), or itch and inflammation (the dermatitis model), or chronic inflammation without itch (the CFA model). In the epidermis, we identified peptidergic fibers-that is, immunoreactive (IR) for calcitonin gene-related peptide or substance P—and non-peptidergic fibers—that is, IR for P2X3. The overall density of nerve fibers was determined using IR for the protein gene product 9.5. In all three models, the density of epidermal peptidergic nerve fibers increased up to five times when compared with a sham-treated control group. In contrast, the density of epidermal non-peptidergic fibers was not increased, except for a small but significant increase in the dry skin model. Chronic inflammation showed an increased density of peptidergic fibers without itch, indicating that increased nerve fiber density is not invariably associated with itch. The finding that different types of skin pathology induced differential changes in nerve fiber density may be used as a diagnostic tool in humans, through skin biopsies, to identify different types of pathology and to monitor the effect of therapies.
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Affiliation(s)
- Barthold N Schüttenhelm
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands; Department of Plastic, Reconstructive and Hand Surgery, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Liron S Duraku
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands; Department of Plastic, Reconstructive and Hand Surgery, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Jouke F Dijkstra
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Erik T Walbeehm
- Department of Plastic Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Jan C Holstege
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands.
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Valtcheva MV, Samineni VK, Golden JP, Gereau RW, Davidson S. Enhanced nonpeptidergic intraepidermal fiber density and an expanded subset of chloroquine-responsive trigeminal neurons in a mouse model of dry skin itch. THE JOURNAL OF PAIN 2015; 16:346-56. [PMID: 25640289 DOI: 10.1016/j.jpain.2015.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 01/08/2015] [Accepted: 01/16/2015] [Indexed: 12/13/2022]
Abstract
UNLABELLED Chronic pruritic conditions are often associated with dry skin and loss of epidermal barrier integrity. In this study, repeated application of acetone and ether followed by water (AEW) to the cheek skin of mice produced persistent scratching behavior with no increase in pain-related forelimb wiping, indicating the generation of itch without pain. Cheek skin immunohistochemistry showed a 64.5% increase in total epidermal innervation in AEW-treated mice compared to water-treated controls. This increase was independent of scratching, because mice prevented from scratching by Elizabethan collars showed similar hyperinnervation. To determine the effects of dry skin treatment on specific subsets of peripheral fibers, we examined Ret-positive, calcitonin gene-related peptide (CGRP)-positive, and glial cell line-derived neurotrophic factor family receptor α3 (GFRα3)-positive intraepidermal fiber density. AEW treatment increased Ret-positive fibers but not CGRP-positive or GFRα3-positive fibers, suggesting that a specific subset of nonpeptidergic fibers could contribute to dry skin itch. To test whether trigeminal ganglion neurons innervating the cheek exhibited altered excitability after AEW treatment, primary cultures of retrogradely labeled neurons were examined using whole-cell patch clamp electrophysiology. AEW treatment produced no differences in measures of excitability compared to water-treated controls. In contrast, a significantly higher proportion of trigeminal ganglion neurons was responsive to the nonhistaminergic pruritogen chloroquine after AEW treatment. We conclude that nonpeptidergic, Ret-positive fibers and chloroquine-sensitive neurons may contribute to dry skin pruritus. PERSPECTIVE This study examines the underlying neurobiological mechanisms of persistent dry skin itch. Our results indicate that nonpeptidergic epidermal hyperinnervation and nonhistaminergic pruritic receptors are potential targets for chronic pruritus.
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Affiliation(s)
- Manouela V Valtcheva
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri; Medical Scientist Training Program, Washington University in St. Louis, St. Louis, Missouri
| | - Vijay K Samineni
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Judith P Golden
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Robert W Gereau
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri
| | - Steve Davidson
- Washington University Pain Center and Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri.
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15
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Kardon AP, Polgár E, Hachisuka J, Snyder LM, Cameron D, Savage S, Cai X, Karnup S, Fan CR, Hemenway GM, Bernard CS, Schwartz ES, Nagase H, Schwarzer C, Watanabe M, Furuta T, Kaneko T, Koerber HR, Todd AJ, Ross SE. Dynorphin acts as a neuromodulator to inhibit itch in the dorsal horn of the spinal cord. Neuron 2014; 82:573-86. [PMID: 24726382 PMCID: PMC4022838 DOI: 10.1016/j.neuron.2014.02.046] [Citation(s) in RCA: 244] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2014] [Indexed: 12/15/2022]
Abstract
Menthol and other counterstimuli relieve itch, resulting in an antipruritic state that persists for minutes to hours. However, the neural basis for this effect is unclear, and the underlying neuromodulatory mechanisms are unknown. Previous studies revealed that Bhlhb5−/− mice, which lack a specific population of spinal inhibitory interneurons (B5-I neurons), develop pathological itch. Here we characterize B5-I neurons and show that they belong to a neurochemically distinct subset. We provide cause-and-effect evidence that B5-I neurons inhibit itch and show that dynorphin, which is released from B5-I neurons, is a key neuromodulator of pruritus. Finally, we show that B5-I neurons are innervated by menthol-, capsaicin-, and mustard oil-responsive sensory neurons and are required for the inhibition of itch by menthol. These findings provide a cellular basis for the inhibition of itch by chemical counterstimuli and suggest that kappa opioids may be a broadly effective therapy for pathological itch. Spinal B5-I interneurons function to inhibit itch B5-I neurons release the kappa opioid dynorphin Kappa opioid signaling bidirectionally modulates itch within the spinal cord Spinal B5-I interneurons mediate the inhibition of itch by menthol
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Affiliation(s)
- Adam P Kardon
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Erika Polgár
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Junichi Hachisuka
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Lindsey M Snyder
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Darren Cameron
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Sinead Savage
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Xiaoyun Cai
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Sergei Karnup
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Christopher R Fan
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Gregory M Hemenway
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Carcha S Bernard
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Erica S Schwartz
- University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; Department of Anesthesiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA
| | - Hiroshi Nagase
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Life Science Center of Tsukuba Advanced Research Alliance C-1F, 1-1-1 Tenoudai Tsukuba Ibaraki, Tsukuba 305-8577, Japan
| | - Christoph Schwarzer
- Department of Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Takahiro Furuta
- Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takeshi Kaneko
- Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - H Richard Koerber
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA
| | - Andrew J Todd
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
| | - Sarah E Ross
- Department of Neurobiology, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; University of Pittsburgh Pain Center, University of Pittsburgh, 200 Lothrop St. Pittsburgh, PA 15213, USA; Department of Anesthesiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA.
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16
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Akiyama T, Nagamine M, Carstens MI, Carstens E. Behavioral model of itch, alloknesis, pain and allodynia in the lower hindlimb and correlative responses of lumbar dorsal horn neurons in the mouse. Neuroscience 2014; 266:38-46. [PMID: 24530451 DOI: 10.1016/j.neuroscience.2014.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 02/02/2014] [Accepted: 02/04/2014] [Indexed: 12/01/2022]
Abstract
We have further developed a behavioral model of itch and pain in the lower hindlimb (calf) originally reported by LaMotte et al. (2011) that allows comparisons with responses of lumbar dorsal horn neurons to pruritic and noxious stimuli. Intradermal (id) microinjection of the pruritogens histamine, SLIGRL-NH2 (agonist of PAR-2 and MrgprC11) and chloroquine (agonist of MrgprA3) into the calf of the lower limb elicited significant biting and a small amount of licking directed to the injection site, over a 30-min time course. Following id injection of histamine, low-threshold mechanical stimuli reliably elicited discrete episodes of biting (alloknesis) over a longer time course; significantly less alloknesis was observed following id injection of SLIGRL-NH2. Capsaicin injections elicited licking but little biting. Following id injection of capsaicin, low-threshold mechanical stimuli elicited discrete hindlimb flinches (allodynia) over a prolonged (>2h) time course. In single-unit recordings from superficial lumbar dorsal horn neurons, low-threshold mechanically evoked responses were significantly enhanced, accompanied by receptive field expansion, following id injection of histamine in histamine-responsive neurons. This was not observed in histamine-insensitive neurons, or following id injection of saline or SLIGRL-NH2, regardless of whether the latter activated the neuron or not. These results suggest that itch-responsive neurons are selectively sensitized by histamine but not SLIGRL-NH2 to account for alloknesis. The presently described "calf" model appears to distinguish between itch- and pain-related behavioral responses, and provides a basis to investigate lumbar spinal neural mechanisms underlying itch, alloknesis, pain and allodynia.
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Affiliation(s)
- T Akiyama
- University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, USA
| | - M Nagamine
- University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, USA
| | - M I Carstens
- University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, USA
| | - E Carstens
- University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, USA.
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17
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Bautista DM, Wilson SR, Hoon MA. Why we scratch an itch: the molecules, cells and circuits of itch. Nat Neurosci 2014; 17:175-82. [PMID: 24473265 PMCID: PMC4364402 DOI: 10.1038/nn.3619] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/03/2013] [Indexed: 12/17/2022]
Abstract
Itch is described as an irritating sensation that triggers a desire to scratch. However, this definition hardly seems fitting for the millions of people who suffer from intractable itch. Indeed, the Buddhist philosopher Nāgārjuna more aptly stated, "There is pleasure when an itch is scratched. But to be without an itch is more pleasurable still." Chronic itch is widespread and very difficult to treat. In this review we focus on the molecules, cells and circuits in the peripheral and central nervous systems that drive acute and chronic itch transmission. Understanding the itch circuitry is critical to developing new therapies for this intractable disease.
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Affiliation(s)
- Diana M Bautista
- 1] Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA. [2] Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
| | - Sarah R Wilson
- 1] Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA. [2] Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research/NIH, Bethesda, Maryland, USA
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18
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Abstract
The itch-scratch reflex serves as a protective mechanism in everyday life. However, chronic persistent itching can be devastating. Despite the clinical importance of the itch sensation, its mechanism remains elusive. In the past decade, substantial progress has been made to uncover the mystery of itching. Here, we review the molecules, cells, and circuits known to mediate the itch sensation, which, coupled with advances in understanding the pathophysiology of chronic itching conditions, will hopefully contribute to the development of new anti-itch therapies.
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Affiliation(s)
- Liang Han
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205;
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19
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The kinin B1 receptor mediates alloknesis in a murine model of inflammation. Neurosci Lett 2013; 560:31-5. [PMID: 24355361 DOI: 10.1016/j.neulet.2013.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 12/04/2013] [Accepted: 12/09/2013] [Indexed: 01/02/2023]
Abstract
Noxious stimuli and non-noxious mechanical stimuli elicit itch (alloknesis) instead of pain on skin lesions of patients with atopic dermatitis. We previously found that bradykinin evokes an itch-related scratching response through activation of kinin B1 receptor in skin inflamed using complete Freund's adjuvant. In this study we investigated whether alloknesis is evoked in CFA-inflamed skin and the involvement of kinin receptors. In our results, alloknesis was elicited four days after CFA-inflammation. Furthermore, pretreatment with a B1 receptor antagonist or μ-opioid receptor antagonist significantly reduced alloknesis. In contrast, treatment with a B2 receptor antagonist significantly increased alloknesis. These results suggest that the alloknesis response is mediated by the activation of kinin B1 receptor but antagonized by the B2 receptor in CFA-inflamed mice.
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20
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Abstract
While considerable effort has been made to investigate the neural mechanisms of pain, much less effort has been devoted to itch, at least until recently. However, itch is now gaining increasing recognition as a widespread and costly medical and socioeconomic issue. This is accompanied by increasing interest in the underlying neural mechanisms of itch, which has become a vibrant and rapidly-advancing field of research. The goal of the present forefront review is to describe the recent progress that has been made in our understanding of itch mechanisms.
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Affiliation(s)
- Tasuku Akiyama
- University of California, Davis, Department of Neurobiology, Physiology & Behavior, 1 Shields Avenue, Davis, CA 95616, United States
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21
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Nishida K, Takechi K, Akiyama T, Carstens MI, Carstens E. Scratching inhibits serotonin-evoked responses of rat dorsal horn neurons in a site- and state-dependent manner. Neuroscience 2013; 250:275-81. [PMID: 23867770 DOI: 10.1016/j.neuroscience.2013.07.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 06/30/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
Scratching inhibits pruritogen-evoked responses of neurons in the superficial dorsal horn, implicating a spinal site for scratch inhibition of itch. We investigated if scratching differentially affects neurons depending on whether they are activated by itchy vs. painful stimuli, and if the degree of inhibition depends on the relative location of scratching. We recorded from rat lumbar dorsal horn neurons responsive to intradermal (id) microinjection of serotonin (5-hydroxytryptamine, 5-HT). During the response to 5-HT, scratch stimuli (3mm, 300 mN, 2 Hz, 20s) were delivered at the injection site within the mechanosensitive receptive field (on-site), or 4-30 mm away, outside of the receptive field (off-site). During off-site scratching, 5-HT-evoked firing was significantly attenuated followed by recovery. On-site scratching excited neurons, followed by a significant post-scratch decrease in 5-HT-evoked firing. Most neurons additionally responded to mustard oil (allyl isothiocyanate). Off-site scratching had no effect, while on-site scratching excited the neurons. These results indicate that scratching exerts a state-dependent inhibitory effect on responses of spinal neurons to pruritic but not algesic stimuli. Moreover, on-site scratching first excited neurons followed by inhibition, while off-site scratching immediately evoked the inhibition of pruritogen-evoked activity. This accounts for the suppression of itch by scratching at a distance from the site of the itchy stimulus.
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Affiliation(s)
- K Nishida
- Department of Anesthesiology and Resuscitology, Ehime University School of Medicine, Matsuyama, Japan
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22
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Liu T, Ji RR. New insights into the mechanisms of itch: are pain and itch controlled by distinct mechanisms? Pflugers Arch 2013; 465:1671-85. [PMID: 23636773 DOI: 10.1007/s00424-013-1284-2] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 04/13/2013] [Accepted: 04/14/2013] [Indexed: 12/30/2022]
Abstract
Itch and pain are closely related but distinct sensations. They share largely overlapping mediators and receptors, and itch-responding neurons are also sensitive to pain stimuli. Itch-mediating primary sensory neurons are equipped with distinct receptors and ion channels for itch transduction, including Mas-related G protein-coupled receptors (Mrgprs), protease-activated receptors, histamine receptors, bile acid receptor, toll-like receptors, and transient receptor potential subfamily V1/A1 (TRPV1/A1). Recent progress has indicated the existence of an itch-specific neuronal circuitry. The MrgprA3-expressing primary sensory neurons exclusively innervate the epidermis of skin, and their central axons connect with gastrin-releasing peptide receptor (GRPR)-expressing neurons in the superficial spinal cord. Notably, ablation of MrgprA3-expressing primary sensory neurons or GRPR-expressing spinal cord neurons results in selective reduction in itch but not pain. Chronic itch results from dysfunction of the immune and nervous system and can manifest as neural plasticity despite the fact that chronic itch is often treated by dermatologists. While differences between acute pain and acute itch are striking, chronic itch and chronic pain share many similar mechanisms, including peripheral sensitization (increased responses of primary sensory neurons to itch and pain mediators), central sensitization (hyperactivity of spinal projection neurons and excitatory interneurons), loss of inhibitory control in the spinal cord, and neuro-immune and neuro-glial interactions. Notably, painful stimuli can elicit itch in some chronic conditions (e.g., atopic dermatitis), and some drugs for treating chronic pain are also effective in chronic itch. Thus, itch and pain have more similarities in pathological and chronic conditions.
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Affiliation(s)
- Tong Liu
- Pain Signaling and Plasticity Laboratory, Department of Anesthesiology and Neurobiology, Duke University Medical Center, 595 LaSalle Street, GSRB-I, Room 1027A, DUMC 3094, Durham, NC, 27710, USA,
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23
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Mazzardo-Martins L, Martins DF, Stramosk J, Cidral-Filho FJ, Santos ARS. Glycogen synthase kinase 3-specific inhibitor AR-A014418 decreases neuropathic pain in mice: evidence for the mechanisms of action. Neuroscience 2012; 226:411-20. [PMID: 23000630 DOI: 10.1016/j.neuroscience.2012.09.020] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 08/31/2012] [Accepted: 09/08/2012] [Indexed: 11/19/2022]
Abstract
The present study examined the antihyperalgesic effect of a specific inhibitor of Glycogen Synthase Kinase 3 (GSK3), AR-A014418, on the partial ligation of the sciatic nerve (PSNL), a neuropathic pain model in mice and investigated some mechanisms of action. AR-A014418 (0.01-1 mg/kg) administered by intraperitoneal route (i.p.) inhibited mechanical hyperalgesia. This action started 30 min after i.p. administration and remained significant up to 2 h. When administered daily for 5 days, AR-A014418 (0.3 mg/kg, i.p.) significantly reduced the mechanical hyperalgesia caused by PSNL. Intraperitoneal (i.p.) treatment with AR-A014418 (0.3 mg/kg) also significantly inhibited cold hyperalgesia induced by PSNL. Pre-administration of PCPA (100 mg/kg, i.p., inhibitor of serotonin synthesis) and AMPT (100 mg/kg, i.p., inhibitor of tyrosine hydroxylase), but not l-arginine (600 mg/kg, i.p., a nitric oxide precursor), significantly reduced the mechanical hyperalgesia elicited by AR-A014418. Furthermore, the administration of AR-A014418 significantly prevented the increase of TNF-α (inhibition of 76±8%) and IL-1β (inhibition of 62±10%), but did not alter lumbar spinal cord IL1-ra and IL-10 levels. Finally, intraperitoneal administration of AR-A014418 did not affect locomotor activity in the open-field test. Taken together, these results provide experimental evidence indicating that AR-A014418 produces marked antihyperalgesic effects in neuropathic pain in mice, possibly due to mechanisms that reduce proinflammatory cytokines, as well as increases in serotonergic and catecholaminergic pathways. The present study suggests that GSK3 may be a novel pharmacological target for the treatment of neuropathic pain and AR-A014418 might be a potential molecule of interest for chronic pain relief.
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Affiliation(s)
- L Mazzardo-Martins
- Laboratório de Neurobiologia da Dor e Inflamação, Departamento de Ciências Fisiológicas, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário-Trindade, Florianópolis, SC, Brazil
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24
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Abstract
Lightly touching normal skin near a site of itch can elicit itch sensation, a phenomenon known as alloknesis. To investigate the neural mechanisms of alloknesis, we have developed an animal model. Low-threshold mechanical stimulation of the skin normally does not elicit any response in naïve C57/BL6 mice. Following acute intradermal (id) injection of histamine in the rostral back, mechanical stimulation 7 mm from the injection site elicited discrete hindlimb scratch bouts directed toward the stimulus. This began at 10 min and peaked 20–40 min post-histamine, declining over the next hour. Histamine itself elicited bouts of scratching not associated with the mechanical stimulus, that ceased after 30 min. Histamine- and touch-evoked scratching was inhibited by the μ-opiate antagonist naltrexone. Touch-evoked scratching was observed following id 5-HT, a PAR-4 agonist and a MrgprC11 agonist BAM8-22, but not chloroquine or a PAR-2 agonist. The histamine H1 receptor antagonist terfenadine prevented scratching and alloknesis evoked by histamine, but not 5-HT, a PAR-4 agonist or a MrgprC11 agonist. In mice with experimental dry skin, there was a time-dependent increase in spontaneous and touch-evoked scratching. This animal model, which to our knowledge is previously unreported, appears to be useful to investigate neural mechanisms of itch and alloknesis.
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25
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Abstract
In psychophysical experiments, humans use different verbal responses to pruritic and algesic chemical stimuli to indicate the different qualities of sensation they feel. A major challenge for behavioural models in the mouse of chemical itch and pain in humans is to devise experimental protocols that provide the opportunity for the animal to exhibit a multiplicity of responses as well. One basic criterion is that chemicals that evoke primarily itch or pain in humans should elicit different types of responses when applied in the same way to the mouse. Meeting this criterion is complicated by the fact that the type of behavioural responses exhibited by the mouse depends in part on the site of chemical application such as the nape of the neck that evokes only scratching with the hind paw versus the hind limb that elicits licking and biting. Here, we review to what extent mice behaviourally differentiate chemicals that elicit itch versus pain in humans.
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Affiliation(s)
- Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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26
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Abstract
This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, USA.
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27
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Transmitters and pathways mediating inhibition of spinal itch-signaling neurons by scratching and other counterstimuli. PLoS One 2011; 6:e22665. [PMID: 21818363 PMCID: PMC3144926 DOI: 10.1371/journal.pone.0022665] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 06/28/2011] [Indexed: 12/12/2022] Open
Abstract
Scratching relieves itch, but the underlying neural mechanisms are poorly understood. We presently investigated a role for the inhibitory neurotransmitters GABA and glycine in scratch-evoked inhibition of spinal itch-signaling neurons in a mouse model of chronic dry skin itch. Superficial dorsal horn neurons ipsilateral to hindpaw dry skin treatment exhibited a high level of spontaneous firing that was significantly attenuated by cutaneous scratching, pinch and noxious heat. Scratch-evoked inhibition was nearly abolished by spinal delivery of the glycine antagonist, strychnine, and was markedly attenuated by respective GABAA and GABAB antagonists bicuculline and saclofen. Scratch-evoked inhibition was also significantly attenuated (but not abolished) by interruption of the upper cervical spinal cord, indicating the involvement of both segmental and suprasegmental circuits that engage glycine- and GABA-mediated inhibition of spinal itch-signaling neurons by noxious counterstimuli.
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28
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Akiyama T, Carstens MI, Carstens E. Enhanced responses of lumbar superficial dorsal horn neurons to intradermal PAR-2 agonist but not histamine in a mouse hindpaw dry skin itch model. J Neurophysiol 2011; 105:2811-7. [PMID: 21430273 DOI: 10.1152/jn.01124.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic itch is symptomatic of many skin conditions and systemic diseases. Little is known about pathophysiological alterations in itch-signaling neural pathways associated with chronic itch. We used a mouse model of hindpaw chronic dry skin itch to investigate properties of presumptive itch-signaling neurons. Neurons in the lumbar superficial dorsal horn ipsilateral to hindpaw dry skin treatment exhibited a high level of spontaneous activity that was inhibited by scratching the plantar surface. Most spontaneously active units exhibited further increases in firing rate following intradermal injection of an agonist of the protease-activated receptor PAR-2, or histamine. The large majority of pruritogen-responsive units also responded to capsaicin and allyl isothiocyanate. For neurons ipsilateral to dry skin treatment, responses elicited by the PAR-2 agonist, but not histamine or mechanical stimuli, were significantly larger compared with neurons ipsilateral to vehicle (water) treatment or neurons recorded in naïve (untreated) mice. The spontaneous activity may signal ongoing itch, while enhanced PAR-2 agonist-evoked responses may underlie hyperknesis (enhanced itch), both of which are symptomatic of many chronic itch conditions. The enhancement of neuronal responses evoked by the PAR-2 agonist, but not by histamine or mechanical stimuli, implies that the dry skin condition selectively sensitized PAR-2 agonist-sensitive primary afferent pruriceptors.
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Affiliation(s)
- Tasuku Akiyama
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616, USA
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