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Pei X, Li B, Xu X, Zhang H. Spinal Caspase-6 Contributes to Intrathecal Morphine-induced Acute Itch and Contact Dermatitis-induced Chronic Itch Through Regulating the Phosphorylation of Protein Kinase Mζ in Mice. Neuroscience 2024; 539:21-34. [PMID: 38176610 DOI: 10.1016/j.neuroscience.2023.12.015] [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: 06/30/2023] [Revised: 12/08/2023] [Accepted: 12/28/2023] [Indexed: 01/06/2024]
Abstract
Patients receiving neuraxial treatment with morphine for pain relief often experience a distressing pruritus. Neuroinflammation-mediated plasticity of sensory synapses in the spinal cord is critical for the development of pain and itch. Caspase-6, as an intracellular cysteine protease, is capable of inducing central nociceptive sensitization through regulating synaptic transmission and plasticity. Given the tight interaction between protein kinase Mζ (PKMζ) and excitatory synaptic plasticity, this pre-clinical study investigates whether caspase-6 contributes to morphine-induced itch and chronic itch via PKMζ. Intrathecal morphine and contact dermatitis were used to cause pruritus in mice. Morphine antinociception, itch-induced scratching behaviors, spinal activity of caspase-6, and phosphorylation of PKMζ and ERK were examined. Caspase-6 inhibitor Z-VEID-FMK, exogenous caspase-6 and PKMζ inhibitor ZIP were utilized to reveal the mechanisms and prevention of itch. Herein, we report that morphine induces significant scratching behaviors, which is accompanied by an increase in spinal caspase-6 cleavage and PKMζ phosphorylation (but not expression). Intrathecal injection of Z-VEID-FMK drastically reduces morphine-induced scratch bouts and spinal phosphorylation of PKMζ, without abolishing morphine analgesia. Moreover, intrathecal strategies of ZIP dose-dependently reduce morphine-induced itch-like behaviors. Spinal phosphorylation of ERK following neuraxial morphine is down-regulated by ZIP therapy. Recombinant caspase-6 directly exhibits scratching behaviors and spinal phosphorylation of ERK, which is compensated by PKMζ inhibition. Also, spinal inhibition of caspase-6 and PKMζ reduces the generation and maintenance of dermatitis-induced chronic itch. Together, these findings demonstrate that spinal caspase-6 modulation of PKMζ phosphorylation is important in the development of morphine-induced itch and dermatitis-induced itch in mice.
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Affiliation(s)
- Xuxing Pei
- Department of Anesthesiology and Perioperative Medicine, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou 450003, China
| | - Bing Li
- Department of Anesthesiology and Perioperative Medicine, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou 450003, China
| | - Xiaodong Xu
- Department of Anesthesiology and Perioperative Medicine, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou 450003, China
| | - Hui Zhang
- Department of Anesthesiology and Perioperative Medicine, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou 450003, China.
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2
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Gao X, Yang Y, Zhu J, Zhang Y, Wang C, Wang Z, Mi W, Du L. Xanthotoxol relieves itch in mice via suppressing spinal GRP/GRPR signaling. Eur J Pharmacol 2023; 960:176147. [PMID: 37871763 DOI: 10.1016/j.ejphar.2023.176147] [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: 06/20/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 10/25/2023]
Abstract
Although pruritus, commonly known as itch, is a common and debilitating symptom associated with various skin conditions, there is a lack of effective therapies available. Xanthotoxol (XAN), a biologically active linear furocoumarin, shows potential in the treatment of various neurological disorders. In this study, we discovered that administering XAN either through intraperitoneal or intrathecal injections effectively reduced scratching behavior induced by compound 48/80 or chloroquine. Importantly, XAN also substantially alleviates chronic itch in dry skin and allergic contact dermatitis mice. Substantial progress has highlighted the crucial role of gastrin-releasing peptide (GRP)-gastrin-releasing peptide receptor (GRPR) signaling in the dorsal spinal cord in transmitting various types of itch. Our behavior tests revealed that XAN significantly alleviated scratching behaviors induced by intrathecal administration of GRP or GRPR agonist bombesin. Furthermore, XAN reduced the activation of neurons in the spinal cord caused by intrathecal administration of GRP in mice. Moreover, XAN attenuates the activation of spinal GRPR-positive neurons in itchy mice. These findings suggest that XAN mitigates itch in mice by suppressing spinal GRP/GRPR signaling, thereby establishing XAN as a promising therapeutic option for treating pruritus.
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Affiliation(s)
- Xinyi Gao
- School of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Yayue Yang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Science, Institutes of Integrative Medicine, Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Jianyu Zhu
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Science, Institutes of Integrative Medicine, Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Yuxin Zhang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Science, Institutes of Integrative Medicine, Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Chenghao Wang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Science, Institutes of Integrative Medicine, Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China
| | - Zhifei Wang
- School of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Wenli Mi
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Science, Institutes of Integrative Medicine, Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, 200032, China.
| | - Lixia Du
- Department of Biochemistry, School of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
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3
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Saika F, Fukazawa Y, Kishioka S, Kiguchi N. Characterization of spinal microglial activation in a mouse model of imiquimod-induced psoriasis. J Pharmacol Sci 2023; 153:183-187. [PMID: 37973215 DOI: 10.1016/j.jphs.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 09/01/2023] [Accepted: 09/15/2023] [Indexed: 11/19/2023] Open
Abstract
Although microglia are associated with chronic pain, the role of spinal microglia in the regulation of itch remains unclear. In this study, we characterized spinal microglial activation in a mouse model of imiquimod (IMQ)-induced psoriasis. Hypertrophic (activated) microglia were observed throughout the spinal cord after the topical application of IMQ. Furthermore, the mRNA expression of microglial markers and inflammatory mediators was upregulated. Ablation of itch-related sensory neurons using resiniferatoxin decreased itch-related scratching behavior and the number of hypertrophic microglia in the spinal dorsal horn. Conclusively, sensory neuron input may partially contribute to spinal microglial activation after IMQ application.
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Affiliation(s)
- Fumihiro Saika
- Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama 640-8392, Japan; Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama 640-8156, Japan
| | - Yohji Fukazawa
- Department of Anatomy, Kansai University of Health Sciences, Osaka 590-0482, Japan
| | - Shiroh Kishioka
- Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama 640-8392, Japan
| | - Norikazu Kiguchi
- Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama 640-8156, Japan.
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4
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Takanami K, Kuroiwa M, Ishikawa R, Imai Y, Oishi A, Hashino M, Shimoda Y, Sakamoto H, Koide T. Function of gastrin-releasing peptide receptors in ocular itch transmission in the mouse trigeminal sensory system. Front Mol Neurosci 2023; 16:1280024. [PMID: 38098939 PMCID: PMC10719851 DOI: 10.3389/fnmol.2023.1280024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 11/03/2023] [Indexed: 12/17/2023] Open
Abstract
The prevalence of allergic conjunctivitis in itchy eyes has increased constantly worldwide owing to environmental pollution. Currently, anti-allergic and antihistaminic eye drops are used; however, there are many unknown aspects about the neural circuits that transmit itchy eyes. We focused on the gastrin-releasing peptide (GRP) and GRP receptor (GRPR), which are reportedly involved in itch transmission in the spinal somatosensory system, to determine whether the GRP system is involved in itch neurotransmission of the eyes in the trigeminal sensory system. First, the instillation of itch mediators, such as histamine (His) and non-histaminergic itch mediator chloroquine (CQ), exhibited concentration-dependent high levels of eye scratching behavior, with a significant sex differences observed in the case of His. Histological analysis revealed that His and CQ significantly increased the neural activity of GRPR-expressing neurons in the caudal part of the spinal trigeminal nucleus of the medulla oblongata in GRPR transgenic mice. We administered a GRPR antagonist or bombesin-saporin to ablate GRPR-expressing neurons, followed by His or CQ instillation, and observed a decrease in CQ-induced eye-scratching behavior in the toxin experiments. Intracisternal administration of neuromedin C (NMC), a GRPR agonist, resulted in dose-dependent excessive facial scratching behavior, despite the absence of an itch stimulus on the face. To our knowledge, this is the first study to demonstrate that non-histaminergic itchy eyes were transmitted centrally via GRPR-expressing neurons in the trigeminal sensory system, and that NMC in the medulla oblongata evoked facial itching.
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Affiliation(s)
- Keiko Takanami
- Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima, Japan
- Genetics, Research Organization of Information and Systems, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
- Department of Environmental Health, Faculty of Human Life and Environmental Sciences, Nara Women’s University, Nara, Japan
| | - Masaya Kuroiwa
- Department of Materials Science and Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| | - Ren Ishikawa
- Department of Materials Science and Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| | - Yuji Imai
- Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima, Japan
- Technical Section, National Institute of Genetics, Mishima, Japan
| | - Akane Oishi
- Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima, Japan
- Technical Section, National Institute of Genetics, Mishima, Japan
| | - Midori Hashino
- Department of Environmental Health, Faculty of Human Life and Environmental Sciences, Nara Women’s University, Nara, Japan
| | - Yasushi Shimoda
- Department of Materials Science and Bioengineering, Nagaoka University of Technology, Nagaoka, Japan
| | - Hirotaka Sakamoto
- Faculty of Environmental, Life, Natural Science and Technology, Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan
- Department of Biology, Faculty of Environmental, Life, Natural Science, and Technology, Okayama University, Okayama, Japan
| | - Tsuyoshi Koide
- Mouse Genomics Resource Laboratory, National Institute of Genetics (NIG), Mishima, Japan
- Genetics, Research Organization of Information and Systems, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
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5
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Haruta-Tsukamoto A, Kanemaru-Kawazoe A, Kogoh Y, Miyahara Y, Funahashi H, Hirano Y, Nishimori T, Ishida Y. Role of kainate receptors in pruriceptive processing in the mouse spinal cord. Eur J Pharmacol 2023; 957:175998. [PMID: 37597648 DOI: 10.1016/j.ejphar.2023.175998] [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: 05/15/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 08/21/2023]
Abstract
Pruritus, including neuropathic and psychogenic pruritus, is an unpleasant feeling that causes a desire to scratch, which negatively impacts physical and psychological aspects of daily life. Nonetheless, little is known about the neural mechanisms involved in pruritus. Glutamate is a predominant excitatory neurotransmitter in the mammalian central nervous system and exerts its effects by binding to various glutamate receptors, including kainate (KA) receptors; however, the precise involvement of each glutamate receptor in pruriceptive processing remains unclear, particularly that of KA receptors. Therefore, the roles of KA receptors in histamine-dependent and -independent itch were investigated using CNQX, an AMPA/KA receptors antagonist, UBP310 and UBP302, antagonists of KA receptors, and small interfering (si)RNAs against KA receptor subunits in mice with acute and chronic pruritus. The effects of KA receptor antagonists on histamine-induced c-Fos expression in the spinal cord were also examined. The intrathecal administration of CNQX reduced the number of scratching events induced by histamine and chloroquine. On the other hand, UBP310 or UBP302 and the siRNAs of KA receptor subunits 1-3 significantly inhibited the induction of scratching events in mice treated with histamine, while no significant change was observed in the induction of spontaneous scratching events in mice with chronic pruritus. In addition, antagonists of KA receptors attenuated c-Fos expression in the superficial layers of the dorsal horn induced by histamine. These results indicate that KA receptors are involved in acute pruriceptive processing in the spinal cord induced by histamine, but not chloroquine or chronic itch.
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Affiliation(s)
- Ayaka Haruta-Tsukamoto
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan; Nozaki Hospital, 5567 Tsunehisa, Miyazaki City, Miyazaki, 880-0916, Japan.
| | - Anna Kanemaru-Kawazoe
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Yoichiro Kogoh
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Yu Miyahara
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Hideki Funahashi
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Yoji Hirano
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Toshikazu Nishimori
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
| | - Yasushi Ishida
- Department of Psychiatry, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki City, Miyazaki, 889-1692, Japan
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6
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Ueda Y, Uta D, Furue H, Ohtubo Y. An electrophysiological method for evaluation of topical antipruritic drugs on itch-related neuronal activities in the spinal cord in hairless mice. Eur J Pharmacol 2023; 952:175798. [PMID: 37207968 DOI: 10.1016/j.ejphar.2023.175798] [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: 12/28/2022] [Revised: 04/29/2023] [Accepted: 05/16/2023] [Indexed: 05/21/2023]
Abstract
To evaluate the effects of antipruritic drugs, it is important to determine whether the neural responses induced by physiological itch stimuli are suppressed. Although there are several behavioral assessments for topical antipruritic drugs applied to the skin, there are few established methods at neuronal levels using in vivo electrophysiological recordings for predicting local efficacy of antipruritic drugs for cutaneous application. To establish an assessment of topical antipruritic drugs applied to skin using in vivo extracellular recording from neurons in the superficial dorsal horn, we examined the relationships between itch-related biting behavior and spinal neuronal responses elicited by intradermal injection of pruritogen serotonin (5-HT) in hairless mice. The efficacy of topical occlusive application of local anesthetics was also evaluated by an in vivo electrophysiological method. 5-HT significantly increased the firing frequency in spinal neurons. The spinal firing frequency time course was similar to that of the biting behavior after the 5-HT injections. The 5-HT-induced spinal responses were significantly decreased by topical occlusive application of lidocaine or a Nav 1.7 channel blocker to the calf. The intradermal 5-HT injection-induced spinal neuronal responses appeared to be suppressed by topical occlusive application of lidocaine or a Nav1.7 channel blocker. The electrophysiological method for evaluating topical antipruritic drugs may be beneficial in assessing local effects on the skin.
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Affiliation(s)
- Yuhki Ueda
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, Japan; Drug Development Laboratories, Kyoto R&D Center, Drug Development Research Laboratories, Maruho Co., Ltd., Kyoto, Japan.
| | - Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Japan.
| | - Yoshitaka Ohtubo
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Kitakyushu, Japan.
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7
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Structures of human gastrin-releasing peptide receptors bound to antagonist and agonist for cancer and itch therapy. Proc Natl Acad Sci U S A 2023; 120:e2216230120. [PMID: 36724251 PMCID: PMC9963752 DOI: 10.1073/pnas.2216230120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Gastrin releasing peptide receptor (GRPR), a member of the bombesin (BBN) G protein-coupled receptors, is aberrantly overexpressed in several malignant tumors, including those of the breast, prostate, pancreas, lung, and central nervous system. Additionally, it also mediates non-histaminergic itch and pathological itch conditions in mice. Thus, GRPR could be an attractive target for cancer and itch therapy. Here, we report the inactive state crystal structure of human GRPR in complex with the non-peptide antagonist PD176252, as well as two active state cryo-electron microscopy (cryo-EM) structures of GRPR bound to the endogenous peptide agonist gastrin-releasing peptide and the synthetic BBN analog [D-Phe6, β-Ala11, Phe13, Nle14] Bn (6-14), in complex with Gq heterotrimers. These structures revealed the molecular mechanisms for the ligand binding, receptor activation, and Gq proteins signaling of GRPR, which are expected to accelerate the structure-based design of GRPR antagonists and agonists for the treatments of cancer and pruritus.
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8
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Uta D, Kiyohara K, Nagaoka Y, Kino Y, Fujita T. Developing a Novel Method for the Analysis of Spinal Cord-Penile Neurotransmission Mechanisms. Int J Mol Sci 2023; 24:ijms24021434. [PMID: 36674942 PMCID: PMC9861114 DOI: 10.3390/ijms24021434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/08/2023] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
Sexual dysfunction can be caused by impaired neurotransmission from the peripheral to the central nervous system. Therefore, it is important to evaluate the input of sensory information from the peripheral genital area and investigate the control mechanisms in the spinal cord to clarify the pathological basis of sensory abnormalities in the genital area. However, an in vivo evaluation system for the spinal cord-penile neurotransmission mechanism has not yet been developed. Here, urethane-anesthetized rats were used to evaluate neuronal firing induced by innocuous or nociceptive stimulation of the penis using extracellular recording or patch-clamp techniques in the lumbosacral spinal dorsal horn and electrophysiological evaluation in the peripheral pelvic nerves. As a result, innocuous and nociceptive stimuli-evoked neuronal firing was successfully recorded in the deep and superficial spinal dorsal horns, respectively. The innocuous stimuli-evoked nerve firing was also recorded in the pelvic nerve. These firings were suppressed by lidocaine. To the best of our knowledge, this is the first report of a successful quantitative evaluation of penile stimuli-evoked neuronal firing. This method is not only useful for analyzing the pathological basis of spinal cord-penile neurotransmission in sexual dysfunction but also provides a useful evaluation system in the search for new treatments.
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Affiliation(s)
- Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
- Correspondence: ; Tel.: +81-76-434-7513
| | - Kazuhiro Kiyohara
- Research Unit/Neuroscience, Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, Yokohama 227-0033, Japan
| | - Yuuya Nagaoka
- Research Unit/Neuroscience, Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, Yokohama 227-0033, Japan
| | - Yurika Kino
- Digital Transformation Department, Mitsubishi Tanabe Pharma Corporation, Tokyo 100-8205, Japan
| | - Takuya Fujita
- Research Unit/Neuroscience, Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, Yokohama 227-0033, Japan
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9
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Critical Players and Therapeutic Targets in Chronic Itch. Int J Mol Sci 2022; 23:ijms23179935. [PMID: 36077340 PMCID: PMC9456029 DOI: 10.3390/ijms23179935] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/28/2022] [Accepted: 08/29/2022] [Indexed: 12/04/2022] Open
Abstract
Chronic itch is one of the most prominent clinical characteristics of diverse systematic diseases. It is a devastating sensation in pathological diseases. Despite its importance, there are no FDA-labelled drugs specifically geared toward chronic itch. The associated complex pathogenesis and diverse causes escalate chronic itch to being one of the top challenges in healthcare. Humanized antibodies against IL-13, IL-4, and IL-31 proved effective in treatment of itch-associated atopic dermatitis but remain to be validated in chronic itch. There are still no satisfactory anti-itch therapeutics available toward itch-related neuropeptides including GRP, BNP, SST, CGRP, and SP. The newly identified potential itch targets including OSM, NMB, glutamate, periostin, and Serpin E1 have opened new avenues for therapeutic development. Proof-of-principle studies have been successfully performed on antagonists against these proteins and their receptors in itch treatment in animal models. Their translational interventions in humans need to be evaluated. It is of great importance to summarize and compare the newly emerging knowledge on chronic itch and its pathways to promote the development of novel anti-itch therapeutics. The goal of this review is to analyze the different physiologies and pathophysiologies of itch mediators, whilst assessing their suitability as new targets and discussing future therapeutic development.
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10
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Takanami K, Oti T, Kobayashi Y, Hasegawa K, Ito T, Tsutsui N, Ueda Y, Carstens E, Sakamoto T, Sakamoto H. Characterization of the expression of gastrin-releasing peptide and its receptor in the trigeminal and spinal somatosensory systems of Japanese macaque monkeys: Insight into humans. J Comp Neurol 2022; 530:2804-2819. [PMID: 35686563 DOI: 10.1002/cne.25376] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 11/06/2022]
Abstract
Gastrin-releasing peptide (GRP) and its receptor (GRPR) have been identified as itch mediators in the spinal and trigeminal somatosensory systems in rodents. In primates, there are few reports of GRP/GRPR expression or function in the spinal sensory system and virtually nothing is known in the trigeminal system. The aim of the present study was to characterize GRP and GRPR in the trigeminal and spinal somatosensory system of Japanese macaque monkeys (Macaca fuscata). cDNA encoding GRP was isolated from the macaque dorsal root ganglion (DRG) and exhibited an amino acid sequence that was highly conserved among mammals and especially in primates. Immunohistochemical analysis demonstrated that GRP was expressed mainly in the small-sized trigeminal ganglion and DRG in adult macaque monkeys. Densely stained GRP-immunoreactive (ir) fibers were observed in superficial layers of the spinal trigeminal nucleus caudalis (Sp5C) and the spinal cord. In contrast, GRP-ir fibers were rarely observed in the principal sensory trigeminal nucleus and oral and interpolar divisions of the spinal trigeminal nucleus. cDNA cloning, in situ hybridization, and Western blot revealed substantial expression of GRPR mRNA and GRPR protein in the macaque spinal dorsal horn and Sp5C. Our Western ligand blot and ligand derivative stain for GRPR revealed that GRP directly bound in the macaque Sp5C and spinal dorsal horn as reported in rodents. Finally, GRP-ir fibers were also detected in the human spinal dorsal horn. The spinal and trigeminal itch neural circuits labeled with GRP and GRPR appear to function also in primates.
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Affiliation(s)
- Keiko Takanami
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Genetics, Mouse Genomics Resources Laboratory, National Institute of Genetics, Sokendai (The Graduate University for Advanced Studies), Shizuoka, Japan.,Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, USA
| | - Takumi Oti
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Biological Sciences, Faculty of Science, Kanagawa University, Kanagawa, Japan
| | - Yasuhisa Kobayashi
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Aquatic Biology, Fisheries, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Koki Hasegawa
- Center for Instrumental Analysis, Kyoto Pharmaceutical University, Kyoto, Japan.,Theranostic Pharmaceuticals Laboratory, Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan
| | - Takashi Ito
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan
| | - Naoaki Tsutsui
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Marine Bioresources, Mie University, Mie, Japan
| | - Yasumasa Ueda
- Department of Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Physiology, Kansai Medical University, Osaka, Japan
| | - Earl Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, USA
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan
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11
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Kanehisa K, Koga K, Maejima S, Shiraishi Y, Asai K, Shiratori-Hayashi M, Xiao MF, Sakamoto H, Worley PF, Tsuda M. Neuronal pentraxin 2 is required for facilitating excitatory synaptic inputs onto spinal neurons involved in pruriceptive transmission in a model of chronic itch. Nat Commun 2022; 13:2367. [PMID: 35501343 PMCID: PMC9061767 DOI: 10.1038/s41467-022-30089-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 04/14/2022] [Indexed: 11/08/2022] Open
Abstract
An excitatory neuron subset in the spinal dorsal horn (SDH) that expresses gastrin-releasing peptide receptors (GRPR) is critical for pruriceptive transmission. Here, we show that glutamatergic excitatory inputs onto GRPR+ neurons are facilitated in mouse models of chronic itch. In these models, neuronal pentraxin 2 (NPTX2), an activity-dependent immediate early gene product, is upregulated in the dorsal root ganglion (DRG) neurons. Electron microscopy reveals that NPTX2 is present at presynaptic terminals connected onto postsynaptic GRPR+ neurons. NPTX2-knockout prevents the facilitation of synaptic inputs to GRPR+ neurons, and repetitive scratching behavior. DRG-specific NPTX2 expression rescues the impaired behavioral phenotype in NPTX2-knockout mice. Moreover, ectopic expression of a dominant-negative form of NPTX2 in DRG neurons reduces chronic itch-like behavior in mice. Our findings indicate that the upregulation of NPTX2 expression in DRG neurons contributes to the facilitation of glutamatergic inputs onto GRPR+ neurons under chronic itch-like conditions, providing a potential therapeutic target.
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Affiliation(s)
- Kensho Kanehisa
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Keisuke Koga
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Hyogo, 663-8501, Japan
| | - Sho Maejima
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, 701-4303, Japan
| | - Yuto Shiraishi
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Konatsu Asai
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Miho Shiratori-Hayashi
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Mei-Fang Xiao
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, United States
| | - Hirotaka Sakamoto
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, 701-4303, Japan
| | - Paul F Worley
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, United States
| | - Makoto Tsuda
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
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12
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Kiguchi N, Ding H, Park SH, Mabry KM, Kishioka S, Shiozawa Y, Alfonso Romero-Sandoval E, Peters CM, Ko MC. Functional roles of neuromedin B and gastrin-releasing peptide in regulating itch and pain in the spinal cord of non-human primates. Biochem Pharmacol 2022; 198:114972. [PMID: 35189108 PMCID: PMC10980179 DOI: 10.1016/j.bcp.2022.114972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/15/2022] [Accepted: 02/15/2022] [Indexed: 11/15/2022]
Abstract
Despite accumulating evidence in rodents, the functional role of neuromedin B (NMB) in regulating somatosensory systems in primate spinal cord is unknown. We aimed to compare the expression patterns of NMB and its receptor (NMBR) and the behavioral effects of intrathecal (i.t.) NMB with gastrin-releasing peptide (GRP) on itch or pain in non-human primates (NHPs). We used six adult rhesus monkeys. The mRNA or protein expressions of NMB, GRP, and their receptors were evaluated by quantitative reverse transcription polymerase chain reaction, immunohistochemistry, or in situ hybridization. We determined the behavioral effects of NMB or GRP via acute thermal nociception, capsaicin-induced thermal allodynia, and itch scratching response assays. NMB expression levels were greater than those of GRP in the dorsal root ganglia and spinal dorsal horn. Conversely, NMBR expression was significantly lower than GRP receptor (GRPR). I.t. NMB elicited only mild scratching responses, whereas GRP caused robust scratching responses. GRP- and NMB-elicited scratching responses were attenuated by GRPR (RC-3095) and NMBR (PD168368) antagonists, respectively. Moreover, i.t. NMB and GRP did not induce thermal hypersensitivity and GRPR and NMBR antagonists did not affect peripherally elicited thermal allodynia. Consistently, NMBR expression was low in both itch- and pain-responsive neurons in the spinal dorsal horn. Spinal NMB-NMBR system plays a minimal functional role in the neurotransmission of itch and pain in primates. Unlike the functional significance of the GRP-GRPR system in itch, drugs targeting the spinal NMB-NMBR system may not effectively alleviate non-NMBR-mediated itch.
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Affiliation(s)
- Norikazu Kiguchi
- Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama City, Wakayama 640-8156, Japan.
| | - Huiping Ding
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Sun H Park
- Department of Cancer Biology and Wake Forest Baptist Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Kelsey M Mabry
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Shiroh Kishioka
- Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama City, Wakayama 640-8392, Japan
| | - Yusuke Shiozawa
- Department of Cancer Biology and Wake Forest Baptist Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | | | - Christopher M Peters
- Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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13
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Glutamate in primary afferents is required for itch transmission. Neuron 2022; 110:809-823.e5. [PMID: 34986325 PMCID: PMC8898340 DOI: 10.1016/j.neuron.2021.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/21/2021] [Accepted: 12/06/2021] [Indexed: 12/13/2022]
Abstract
Whether glutamate or itch-selective neurotransmitters are used to confer itch specificity is still under debate. We focused on an itch-selective population of primary afferents expressing MRGPRA3, which highly expresses Vglut2 and the neuropeptide neuromedin B (Nmb), to investigate this question. Optogenetic stimulation of MRGPRA3+ afferents triggers scratching and other itch-related avoidance behaviors. Using a combination of optogenetics, spinal cord slice recordings, Vglut2 conditional knockout mice, and behavior assays, we showed that glutamate is essential for MRGPRA3+ afferents to transmit itch. We further demonstrated that MRGPRA3+ afferents form monosynaptic connections with both NMBR+ and NMBR- neurons and that NMB and glutamate together can enhance the activity of NMBR+ spinal DH neurons. Moreover, Nmb in MRGPRA3+ afferents and NMBR+ DH neurons are required for chloroquine-induced scratching. Together, our results establish a new model in which glutamate is an essential neurotransmitter in primary afferents for itch transmission, whereas NMB signaling enhances its activities.
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14
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Ohashi N, Uta D, Ohashi M, Baba H. Norepinephrine restores inhibitory tone of spinal lamina X circuitry, thus contributing to analgesia against inflammatory pain. Neuroscience 2022; 490:224-235. [DOI: 10.1016/j.neuroscience.2022.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 03/12/2022] [Accepted: 03/16/2022] [Indexed: 10/18/2022]
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15
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Mishra SK. The Role of CNTNAP2 in Itch Sensation. J Invest Dermatol 2022; 142:251-253. [PMID: 34310948 PMCID: PMC8688288 DOI: 10.1016/j.jid.2021.07.152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/27/2021] [Accepted: 07/05/2021] [Indexed: 01/03/2023]
Affiliation(s)
- Santosh K. Mishra
- CORRESPONDING AUTHOR: Dr. Santosh K. Mishra, 1060 William Moore Drive, Raleigh, NC 27607,
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Estrogens influence female itch sensitivity via the spinal gastrin-releasing peptide receptor neurons. Proc Natl Acad Sci U S A 2021; 118:2103536118. [PMID: 34312228 PMCID: PMC8346901 DOI: 10.1073/pnas.2103536118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Many women exhibit a dramatic increase in itch during pregnancy, but the underlying mechanism is unknown. Here, we demonstrate that the female sex steroid hormone estradiol, but not progesterone, enhances itch-related scratching behavior in female rats elicited by histamine, the prototypical itch mediator in humans. This is associated with an enhancement in histamine-evoked activity of a subset of spinal dorsal horn neurons that express a neuropeptide receptor, gastrin-releasing peptide receptor (GRPR), that was previously shown to be involved in spinal cord processing of itch. These findings may account for why itch sensation varies with estrogen levels and provide a basis for treating histamine-related itch diseases in females by targeting GRPR. There are sex differences in somatosensory sensitivity. Circulating estrogens appear to have a pronociceptive effect that explains why females are reported to be more sensitive to pain than males. Although itch symptoms develop during pregnancy in many women, the underlying mechanism of female-specific pruritus is unknown. Here, we demonstrate that estradiol, but not progesterone, enhances histamine-evoked scratching behavior indicative of itch in female rats. Estradiol increased the expression of the spinal itch mediator, gastrin-releasing peptide (GRP), and increased the histamine-evoked activity of itch-processing neurons that express the GRP receptor (GRPR) in the spinal dorsal horn. The enhancement of itch behavior by estradiol was suppressed by intrathecal administration of a GRPR blocker. In vivo electrophysiological analysis showed that estradiol increased the histamine-evoked firing frequency and prolonged the response of spinal GRP-sensitive neurons in female rats. On the other hand, estradiol did not affect the threshold of noxious thermal pain and decreased touch sensitivity, indicating that estradiol separately affects itch, pain, and touch modalities. Thus, estrogens selectively enhance histamine-evoked itch in females via the spinal GRP/GRPR system. This may explain why itch sensation varies with estrogen levels and provides a basis for treating itch in females by targeting GRPR.
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Zhang Y, Zhang H, Jiang B, Tong X, Yan S, Lu J. Current views on neuropeptides in atopic dermatitis. Exp Dermatol 2021; 30:1588-1597. [PMID: 33963624 DOI: 10.1111/exd.14382] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 12/19/2022]
Abstract
Atopic dermatitis (AD) is a chronic inflammatory skin disease involving skin barrier dysfunction and immune imbalance. However, the mechanism of AD is not clear completely and may be related to heredity and environment. Neuropeptides are a class of peptides secreted by nerve endings, they may play roles in promoting vasodilation, plasma extravasation, chemotaxis of inflammatory cells and mediating pruritus. Since itching and immune cell infiltration are the main manifestations of atopic dermatitis, to further investigate the impact of neuropeptides on AD, our review summarized the mechanisms of several common neuropeptides in AD and hypothesized that neuropeptides may be the novel potential targets in AD treatment.
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Affiliation(s)
- Yue Zhang
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Hanyi Zhang
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Boyue Jiang
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China.,Xiangya School of Medicine, Central South University, Changsha, China
| | - Xiaoliang Tong
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Siyu Yan
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China
| | - Jianyun Lu
- Department of Dermatology, The Third Xiangya Hospital, Central South University, Changsha, China
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18
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Kiguchi N, Fukazawa Y, Saika A, Uta D, Saika F, Nakamura TY, Ko M, Kishioka S. Chemogenetic activation of central gastrin-releasing peptide-expressing neurons elicits itch-related scratching behavior in male and female mice. Pharmacol Res Perspect 2021; 9:e00790. [PMID: 34000759 PMCID: PMC8128314 DOI: 10.1002/prp2.790] [Citation(s) in RCA: 6] [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: 04/07/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
Several lines of evidence have clarified that the key transmission pathways of itching sensation travel from the periphery to the central nervous system (CNS). Despite the functional significance of gastrin-releasing peptide (GRP) and its cognate receptor in the itch processing mechanism in the spinal dorsal horn (SDH), the roles of GRP-expressing (GRP+ ) neurons in different regions remain unclear. This study aimed to determine whether GRP+ neurons in the CNS directly modulated itch processing. To specifically activate spinal and supraspinal GRP neurons by the designer receptors exclusively activated by designer drugs (DREADDs) system, CAG-LSL-Gq-DREADD mice were crossed with GRP-Cre mice, resulting in the development of GRP-hM3Dq mice. Immunohistochemistry showed that hM3Dq was highly expressed in the SDH and brainstem closely related to sensory processing. The intraperitoneal, intrathecal, or intracerebroventricular administration of clozapine-N-oxide, an agonist of hM3Dq, strongly elicited dermatome-dependent itch-related scratching behavior, but did not change pain sensitivity. Importantly, GRP-Gq-DREADD-mediated scratching behavior in GRP-hM3Dq mice was not affected by the ablation of transient receptor potential vanilloid 1+ sensory C-fibers, and it was also observed to a similar degree under chronic itch conditions. Furthermore, there were no significant sex differences in the scratching behavior elicited by GRP-Gq-DREADD, suggesting that itch-dominant roles of central GRP+ neurons might be common in both sexes, at least under normal physiological conditions. These novel findings not only contribute to understanding the functional roles of central GRP+ neurons further, but also propose the development of future effective therapeutics for intractable itching.
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Affiliation(s)
- Norikazu Kiguchi
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
- Department of Physiological SciencesSchool of Pharmaceutical SciencesWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Yohji Fukazawa
- Department of AnatomyKansai University of Health SciencesSennan‐gunOsakaJapan
| | - Ayano Saika
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Daisuke Uta
- Department of Applied PharmacologyFaculty of Pharmaceutical SciencesUniversity of ToyamaToyama CityToyamaJapan
| | - Fumihiro Saika
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Tomoe Y. Nakamura
- Department of PharmacologyWakayama Medical UniversityWakayama CityWakayamaJapan
| | - Mei‐Chuan Ko
- Department of Physiology and PharmacologyWake Forest University School of MedicineWinston‐SalemNCUSA
| | - Shiroh Kishioka
- Faculty of Wakayama Health Care SciencesTakarazuka University of Medical and Health CareWakayama CityWakayamaJapan
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Chemogenetic Activation of CX3CR1-Expressing Spinal Microglia Using Gq-DREADD Elicits Mechanical Allodynia in Male Mice. Cells 2021; 10:cells10040874. [PMID: 33921365 PMCID: PMC8069983 DOI: 10.3390/cells10040874] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 12/11/2022] Open
Abstract
It is important to investigate the sex-dependent roles of microglia in pain hypersensitivity as reactive microglia within the spinal dorsal horn (DH) have been reported to be pivotal in neuropathic pain induction in male rodents upon nerve injury. Here, we aimed at determining the role of sex differences in the behavioral and functional outcomes of the chemogenetic activation of spinal microglia using Gq-designer receptors exclusively activated by designer drugs (Gq-DREADD) driven by the microglia-specific Cx3cr1 promoter. CAG-LSL-human Gq-coupled M3 muscarinic receptors (hM3Dq)-DREADD mice were crossed with CX3C chemokine receptor 1 (CX3CR1)-Cre mice, and immunohistochemistry images revealed that hM3Dq was selectively expressed on Iba1+ microglia, but not on astrocytes and neurons. Intrathecal (i.t.) administration of clozapine-N-oxide (CNO) elicited mechanical allodynia exclusively in male mice. Furthermore, the reactive microglia-dominant molecules that contributed to pain hypersensitivity in CX3CR1-hM3Dq were upregulated in mice of both sexes. The degree of upregulation was greater in male than in female mice. Depletion of spinal microglia using pexidartinib (PLX3397), a colony stimulating factor-1 receptor inhibitor, alleviated the male CX3CR1-hM3Dq mice from pain hypersensitivity and compromised the expression of inflammatory molecules. Thus, the chemogenetic activation of spinal microglia resulted in pain hypersensitivity in male mice, suggesting the sex-dependent molecular aspects of spinal microglia in the regulation of pain.
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Abstract
PURPOSE OF REVIEW The current review aims to update the important findings about molecular and cellular biology of mammalian bombesin-like peptides (BLPs) and their receptors. RECENT FINDINGS Recent identification of synaptic communication between gastrin-releasing peptide (GRP) neurons and GRP receptor (GRPR) neurons in spinal itch relay provides us novel insights into physiology of itch sensation. Neuromedin B (NMB) neurons were found to form connections with subcortical areas associated with arousal, hippocampal theta oscillation, and premotor processing and project to multiple downstream stations to regulate locomotion and hippocampal theta power. In addition to researches regarding the roles of BLPs and their receptors in central nervous system, recent findings reveal that NMB receptor is expressed on helminth-induced type 2 innate lymphoid cells and is regulated by basophils, suggesting an important function of NMB in helminth-induced immune responses. Bombesin transactivates epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and HER3 receptors on human nonsmall-cell lung cancer (NSCLC) cells and elicits downstream signaling cascades and induces formation of both human epidermal growthfactor receptor 3 (HER3)/EGFR and HER3/HER2 heterodimers. Several high-affinity ligands for bombesin receptors were characterized, providing useful tools in investigation of biological roles of those peptides and their receptors. SUMMARY The most exciting findings of BLPs and their receptors in the past year come from studies in central nervous system. In addition, more researches are still underway to probe the molecular mechanisms of those peptides in peripheral tissues and characterize novel synthetic ligands with high affinity for mammalian bombesin receptors.
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Affiliation(s)
- Xiaoqun Qin
- Department of Physiology, Xiangya School of Medicine, Central South University, Changsha, Hunan, PR China
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21
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In Vivo Electrophysiology of Peptidergic Neurons in Deep Layers of the Lumbar Spinal Cord after Optogenetic Stimulation of Hypothalamic Paraventricular Oxytocin Neurons in Rats. Int J Mol Sci 2021; 22:ijms22073400. [PMID: 33810239 PMCID: PMC8036474 DOI: 10.3390/ijms22073400] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/28/2023] Open
Abstract
The spinal ejaculation generator (SEG) is located in the central gray (lamina X) of the rat lumbar spinal cord and plays a pivotal role in the ejaculatory reflex. We recently reported that SEG neurons express the oxytocin receptor and are activated by oxytocin projections from the paraventricular nucleus of hypothalamus (PVH). However, it is unknown whether the SEG responds to oxytocin in vivo. In this study, we analyzed the characteristics of the brain–spinal cord neural circuit that controls male sexual function using a newly developed in vivo electrophysiological technique. Optogenetic stimulation of the PVH of rats expressing channel rhodopsin under the oxytocin receptor promoter increased the spontaneous firing of most lamina X SEG neurons. This is the first demonstration of the in vivo electrical response from the deeper (lamina X) neurons in the spinal cord. Furthermore, we succeeded in the in vivo whole-cell recordings of lamina X neurons. In vivo whole-cell recordings may reveal the features of lamina X SEG neurons, including differences in neurotransmitters and response to stimulation. Taken together, these results suggest that in vivo electrophysiological stimulation can elucidate the neurophysiological response of a variety of spinal neurons during male sexual behavior.
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Li Y, Zhang W, Sun T, Liu B, Manyande A, Xu W, Xiang HB. The Role of Gut Microbiota in Chronic Itch-Evoked Novel Object Recognition-Related Cognitive Dysfunction in Mice. Front Med (Lausanne) 2021; 8:616489. [PMID: 33614682 PMCID: PMC7892771 DOI: 10.3389/fmed.2021.616489] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/06/2021] [Indexed: 01/01/2023] Open
Abstract
The high incidence of patients with chronic itch highlights the importance of fundamental research. Recent advances in the interface of gut microbiota have shed new light into exploring this phenomenon. However, it is unknown whether gut microbiota plays a role in chronic itch in rodents with or without cognitive dysfunction. In this study, the role of gut microbiota in diphenylcyclopropenone (DCP)-evoked chronic itch was investigated in mice and hierarchical cluster analysis of novel object recognition test (ORT) results were used to classify DCP-evoked itch model in mice with or without cognitive dysfunction (CD)-like phenotype and 16S ribosomal RNA (rRNA) gene sequencing was used to compare gut bacterial composition between CD (Susceptible) and Non-CD phenotypes (Unsusceptible) in chronic itch mice. Results showed that the microbiota composition was significantly altered by DCP-evoked chronic itch and chronic itch induced novel object recognition-related CD. However, abnormal gut microbiota composition induced by chronic itch may not be correlated with novel object recognition-related CD.
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Affiliation(s)
- Yujuan Li
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wencui Zhang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Tainning Sun
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Baowen Liu
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Anne Manyande
- School of Human and Social Sciences, University of West London, London, United Kingdom
| | - Weiguo Xu
- Department of Orthopedics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hong-Bing Xiang
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Lin Z, Wang Y, Lin S, Liu D, Mo G, Zhang H, Dou Y. Identification of potential biomarkers for abdominal pain in IBS patients by bioinformatics approach. BMC Gastroenterol 2021; 21:48. [PMID: 33530940 PMCID: PMC7852366 DOI: 10.1186/s12876-021-01626-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 01/25/2021] [Indexed: 12/30/2022] Open
Abstract
Background Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disease characterized by chronic abdominal discomfort and pain. The mechanisms of abdominal pain, as a relevant symptom, in IBS are still unclear. We aimed to explore the key genes and neurobiological changes specially involved in abdominal pain in IBS. Methods Gene expression data (GSE36701) was downloaded from Gene Expression Omnibus database. Fifty-three rectal mucosa samples from 27 irritable bowel syndrome with diarrhea (IBS-D) patients and 40 samples from 21 healthy volunteers as controls were included. Differentially expressed genes (DEGs) between two groups were identified using the GEO2R online tool. Functional enrichment analysis of DEGs was performed on the DAVID database. Then a protein–protein interaction network was constructed and visualized using STRING database and Cytoscape. Results The microarray analysis demonstrated a subset of genes (CCKBR, CCL13, ACPP, BDKRB2, GRPR, SLC1A2, NPFF, P2RX4, TRPA1, CCKBR, TLX2, MRGPRX3, PAX2, CXCR1) specially involved in pain transmission. Among these genes, we identified GRPR, NPFF and TRPA1 genes as potential biomarkers for irritating abdominal pain of IBS patients. Conclusions Overexpression of certain pain-related genes (GRPR, NPFF and TRPA1) may contribute to chronic visceral hypersensitivity, therefore be partly responsible for recurrent abdominal pain or discomfort in IBS patients. Several synapses modification and biological process of psychological distress may be risk factors of IBS.
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Affiliation(s)
- Zhongyuan Lin
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510000, Guangdong, China
| | - Yimin Wang
- Department of Anesthesiology, Guangdong Second Provincial General Hospital, Guangzhou, 510000, Guangdong, China
| | - Shiqing Lin
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510000, Guangdong, China
| | - Decheng Liu
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510000, Guangdong, China
| | - Guohui Mo
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510000, Guangdong, China
| | - Hui Zhang
- Department of Anesthesiology, Guangdong Second Provincial General Hospital, Guangzhou, 510000, Guangdong, China.
| | - Yunling Dou
- Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510000, Guangdong, China.
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Critical role of GRP receptor-expressing neurons in the spinal transmission of imiquimod-induced psoriatic itch. Neuropsychopharmacol Rep 2020. [PMID: 32584520 DOI: 10.3760/cma.j.cn131073.20200218.00307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
AIM Ample evidence indicates that gastrin-releasing peptide receptor (GRPR)-expressing neurons play a critical role in the transmission of acute itch. However, the pathophysiology of spinal mechanisms underlying intractable itch such as psoriasis remains unclear. In this study, we aimed to determine whether itch-responsive GRPR+ neurons contribute to the spinal transmission of imiquimod (IMQ)-induced psoriatic itch. METHODS To generate a psoriasis model, C57BL/6J mice received a daily topical application of 5% IMQ cream on their shaved back skin for 7-10 consecutive days. GRP+ neurons were inhibited using Cre-dependent expression of Gi-designer receptors exclusively activated by designer drugs (DREADDs), while GRPR+ neurons were ablated by intrathecal administration of bombesin-saporin. RESULTS Repeated topical application of IMQ elicited psoriasis-like dermatitis and scratching behaviors. The mRNA expression levels of GRP and GRPR were upregulated in the cervical spinal dorsal horn (SDH) on days 7 and 10 after IMQ application. Either chemogenetic silencing of GRP+ neurons by Gi-DREADD or ablation of GRPR+ neurons significantly attenuated IMQ-induced scratching behaviors. CONCLUSION The GRP-GRPR system might be enhanced in the SDH, and itch-responsive GRPR+ neurons largely contribute to intractable itch in a mouse model of psoriasis.
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Kiguchi N, Saika F, Fukazawa Y, Matsuzaki S, Kishioka S. Critical role of GRP receptor-expressing neurons in the spinal transmission of imiquimod-induced psoriatic itch. Neuropsychopharmacol Rep 2020; 40:287-290. [PMID: 32584520 PMCID: PMC7722649 DOI: 10.1002/npr2.12120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/11/2020] [Accepted: 05/22/2020] [Indexed: 11/08/2022] Open
Abstract
AIM Ample evidence indicates that gastrin-releasing peptide receptor (GRPR)-expressing neurons play a critical role in the transmission of acute itch. However, the pathophysiology of spinal mechanisms underlying intractable itch such as psoriasis remains unclear. In this study, we aimed to determine whether itch-responsive GRPR+ neurons contribute to the spinal transmission of imiquimod (IMQ)-induced psoriatic itch. METHODS To generate a psoriasis model, C57BL/6J mice received a daily topical application of 5% IMQ cream on their shaved back skin for 7-10 consecutive days. GRP+ neurons were inhibited using Cre-dependent expression of Gi-designer receptors exclusively activated by designer drugs (DREADDs), while GRPR+ neurons were ablated by intrathecal administration of bombesin-saporin. RESULTS Repeated topical application of IMQ elicited psoriasis-like dermatitis and scratching behaviors. The mRNA expression levels of GRP and GRPR were upregulated in the cervical spinal dorsal horn (SDH) on days 7 and 10 after IMQ application. Either chemogenetic silencing of GRP+ neurons by Gi-DREADD or ablation of GRPR+ neurons significantly attenuated IMQ-induced scratching behaviors. CONCLUSION The GRP-GRPR system might be enhanced in the SDH, and itch-responsive GRPR+ neurons largely contribute to intractable itch in a mouse model of psoriasis.
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Affiliation(s)
- Norikazu Kiguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Fumihiro Saika
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Yohji Fukazawa
- Department of Anatomy, Kansai University of Health Sciences, Osaka, Japan
| | - Shinsuke Matsuzaki
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Shiroh Kishioka
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan.,Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama, Japan
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Saika F, Matsuzaki S, Kobayashi D, Ideguchi Y, Nakamura TY, Kishioka S, Kiguchi N. Chemogenetic Regulation of CX3CR1-Expressing Microglia Using Gi-DREADD Exerts Sex-Dependent Anti-Allodynic Effects in Mouse Models of Neuropathic Pain. Front Pharmacol 2020; 11:925. [PMID: 32636748 PMCID: PMC7318895 DOI: 10.3389/fphar.2020.00925] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/08/2020] [Indexed: 12/25/2022] Open
Abstract
Despite growing evidence suggesting that spinal microglia play an important role in the molecular mechanism underlying experimental neuropathic pain (NP) in male rodents, evidence regarding the sex-dependent role of these microglia in NP is insufficient. In this study, we evaluated the effects of microglial regulation on NP using Gi-designer receptors exclusively activated by designer drugs (Gi-DREADD) driven by the microglia-specific Cx3cr1 promoter. For the Cre-dependent expression of human Gi-coupled M4 muscarinic receptors (hM4Di) in CX3C chemokine receptor 1-expressing (CX3CR1+) cells, R26-LSL-hM4Di-DREADD mice were crossed with CX3CR1-Cre mice. Mouse models of NP were generated by partial sciatic nerve ligation (PSL) and treatment with anti-cancer agent paclitaxel (PTX) or oxaliplatin (OXA), and mechanical allodynia was evaluated using the von Frey test. Immunohistochemistry revealed that hM4Di was specifically expressed on Iba1+ microglia, but not on astrocytes or neurons in the spinal dorsal horn of CX3CR1-hM4Di mice. PSL-induced mechanical allodynia was significantly attenuated by systemic (intraperitoneal, i.p.) administration of 10 mg/kg of clozapine N-oxide (CNO), a hM4Di-selective ligand, in male CX3CR1-hM4Di mice. The mechanical threshold in naive CX3CR1-hM4Di mice was not altered by i.p. administration of CNO. Consistently, local (intrathecal, i.t.) administration of CNO (20 nmol) significantly relieved PSL-induced mechanical allodynia in male CX3CR1-hM4Di mice. However, neither i.p. nor i.t. administration of CNO affected PSL-induced mechanical allodynia in female CX3CR1-hM4Di mice. Both i.p. and i.t. administration of CNO relieved PTX-induced mechanical allodynia in male CX3CR1-hM4Di mice, and a limited effect of i.p. CNO was observed in female CX3CR1-hM4Di mice. Unlike PTX-induced allodynia, OXA-induced mechanical allodynia was slightly improved, but not significantly relieved, by i.p. administration of CNO in both male and female CX3CR1-hM4Di mice. These results suggest that spinal microglia can be regulated by Gi-DREADD and support the notion that CX3CR1+ spinal microglia play sex-dependent roles in nerve injury-induced NP; however, their roles may vary among different models of NP.
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Affiliation(s)
- Fumihiro Saika
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Shinsuke Matsuzaki
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Daichi Kobayashi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan.,Department of Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yuya Ideguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Tomoe Y Nakamura
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Shiroh Kishioka
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan.,Faculty of Wakayama Health Care Sciences, Takarazuka University of Medical and Health Care, Wakayama, Japan
| | - Norikazu Kiguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
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