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Cyril AC, Jan RK, Radhakrishnan R. Pain in chronic prostatitis and the role of ion channels: a brief overview. Br J Pain 2022; 16:50-59. [PMID: 35111314 PMCID: PMC8801692 DOI: 10.1177/20494637211015265] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Prostatitis is the third most common urologic condition affecting more than half the male population at some point in their lives. There are different categories of prostatitis, of which approximately 90% of cases can be classified under the National Institute of Health (NIH) type III category (chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)) with no causative agents identified. CP/CPPS is associated with several symptoms, of which the most prominent being chronic pain. Despite its high incidence, pain management in patients with CP/CPPS has been poor, possibly due to the lack of understanding of aetiological factors and mechanisms underlying pain development. METHODS An extensive literature search of published articles on the molecular mechanisms of pain in CP/CPPS was conducted using PubMed and Google Scholar search engines (https://pubmed.ncbi.nlm.nih.gov and https://scholar.google.com). The terms used for the search were: prostatitis, pain mechanism in CP/CPPS, prostatitis pain models, acid-sensing ion channels (ASICs), transient receptor potential vanilloid type 1 (TRPVs), purinergic channels (P2X) in prostatitis pain mechanism and inflammatory mediators in CP/CPPS. The papers were identified based on the title and abstract, and after excluding the articles that did not emphasize the pain mechanism in CP/CPPS. Ninety-five articles (36 review and 59 original research papers) met our criteria and were included in the review. RESULTS A number of inflammatory mediator molecules and pain channels, including ASICs, transient receptor potential vanilloid channels (TRPVs) and P2Xs have been investigated for their role in prostatitis pain pathology using various animal models. CONCLUSION This review summarizes the pain mechanisms in CP/CPPS focusing on the inflammatory mediators, neurotransmitters, pain-transducing ion channels and small animal models developed for studying prostatitis.
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Affiliation(s)
| | | | - Rajan Radhakrishnan
- Rajan Radhakrishnan, College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Building 14, Dubai Healthcare City, P.O Box 505055, Dubai, UAE.
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2
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Fabbretti E. P2X3 receptors are transducers of sensory signals. Brain Res Bull 2019; 151:119-124. [PMID: 30660716 DOI: 10.1016/j.brainresbull.2018.12.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 11/27/2018] [Accepted: 12/20/2018] [Indexed: 12/12/2022]
Abstract
Peripheral stimuli are transduced by specific receptors expressed by sensory neurons and are further processed in the dorsal horn of spinal cord before to be transmitted to the brain. While relative few receptor subtypes mediate the initial depolarisation of sensory neurons, an impressive number of molecules and ion channels integrate these inputs into coded signals. Soluble mediators and ambient conditions further shape these processes, potentially triggering peripheral and central sensitisation, or sensory downregulation. Extracellular ATP is a major signaling molecule that acts via purinergic receptors and is a powerful modulator of cell communication as well as a neurotransmitter at peripheral/central synapses. In particular, ATP-mediated signals are transduced by P2X3 receptors expressed mainly by peripheral sensory neurons. Recent evidence suggests that P2X3 receptor function not only induces neuron depolarisation and firing with consequent neurotransmitter release, but it also triggers intracellular molecular changes that amplify purinergic signaling with important consequences.
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Affiliation(s)
- Elsa Fabbretti
- Department of Life Science, University of Trieste, via Giorgieri 5, 34127, Trieste, Italy.
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Sasaguri T, Taguchi T, Murata Y, Kobayashi K, Iizasa S, Iizasa E, Tsuda M, Hirakawa N, Hara H, Yoshida H, Yasaka T. Interleukin-27 controls basal pain threshold in physiological and pathological conditions. Sci Rep 2018; 8:11022. [PMID: 30038376 PMCID: PMC6056516 DOI: 10.1038/s41598-018-29398-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 07/10/2018] [Indexed: 12/23/2022] Open
Abstract
Numerous studies have shown that pain sensation is affected by various immune molecules, such as cytokines, in tissues comprising the sensory pathway. Specifically, it has been shown that interleukin (IL)-17 promotes pain behaviour, but IL-10 suppresses it. IL-27 has been reported to have an anti-inflammatory effect through regulation of T cell differentiation, resulting in reduced IL-17 and induction of IL-10. Thus, we hypothesised that IL-27 would have some regulatory role in pain sensation. Here, we provide evidence that endogenous IL-27 constitutively controls thresholds for thermal and mechanical sensation in physiological and pathological conditions. Mice lacking IL-27 or its receptor WSX-1 spontaneously showed chronic pain-like hypersensitivity. Reconstitution of IL-27 in IL-27-deficient mice reversed thermal and mechanical hypersensitive behaviours. Thus, unlike many other cytokines induced by inflammatory events, IL-27 appears to be constitutively produced and to control pain sensation. Furthermore, mice lacking IL-27/WSX-1 signalling showed additional hypersensitivity when subjected to inflammatory or neuropathic pain models. Our results suggest that the mechanisms underlying hypersensitive behaviours caused by the ablation of IL-27/WSX-1 signalling are different from those underlying established chronic pain models. This novel pain control mechanism mediated by IL-27 might indicate a new mechanism for the chronic pain hypersensitivity.
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Affiliation(s)
- Tomoko Sasaguri
- Department of Anesthesiology & Critical Care Medicine, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Toru Taguchi
- Department of Physical Therapy, Niigata University of Health and Welfare, 1398 Shimami-cho, Kita-ku, Niigata, 950-3198, Japan.,Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Yuzo Murata
- Division of Histology and Neuroanatomy, Department of Anatomy & Physiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Kimiko Kobayashi
- Department of Anatomy and Neuroscience, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan
| | - Sayaka Iizasa
- Department of Biological Science and Technology, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-8580, Japan
| | - Ei'ichi Iizasa
- Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Naomi Hirakawa
- Department of Anesthesiology & Critical Care Medicine, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Hiromitsu Hara
- Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan
| | - Hiroki Yoshida
- Division of Molecular and Cellular Immunoscience, Department of Biomolecular Sciences, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
| | - Toshiharu Yasaka
- Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan.
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4
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Choi HS, Lee MJ, Choi SR, Smeester BA, Beitz AJ, Lee JH. Spinal Sigma-1 Receptor-mediated Dephosphorylation of Astrocytic Aromatase Plays a Key Role in Formalin-induced Inflammatory Nociception. Neuroscience 2018; 372:181-191. [PMID: 29289721 DOI: 10.1016/j.neuroscience.2017.12.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 01/08/2023]
Abstract
Aromatase is a key enzyme responsible for the biosynthesis of estrogen from testosterone. Although recent evidence indicates that spinal cord aromatase participates in nociceptive processing, the mechanisms underlying its regulation and its involvement in nociception remain unclear. The present study focuses on the potential role of astrocyte aromatase in formalin-induced acute pain and begins to uncover one mechanism by which spinal aromatase activation is controlled. Following intraplantar formalin injection, nociceptive responses were quantified and immunohistochemistry/co-immunoprecipitation assays were used to investigate the changes in spinal Fos expression and the phospho-serine levels of spinal aromatase. Intrathecal (i.t.) injection of letrozole (an aromatase inhibitor) mitigated both the late phase formalin-induced nociceptive responses and formalin-induced spinal Fos expression. Furthermore, formalin-injected mice showed significantly reduced phospho-serine levels of aromatase, which is associated with the rapid activation of this enzyme. However, sigma-1 receptor inhibition with i.t. BD1047 blocked the dephosphorylation of aromatase and potentiated the pharmacological effect of letrozole on formalin-induced nociceptive responses. In addition, i.t. administration of a sub-effective dose of BD1047 potentiated the pharmacological effect of cyclosporin A (a calcineurin inhibitor) on both the formalin-induced reduction in phospho-serine levels of aromatase and nociceptive behavior. These results suggest that dephosphorylation is an important regulatory mechanism involved in the rapid activation of aromatase and that spinal sigma-1 receptors mediate this dephosphorylation of aromatase through an intrinsic calcineurin pathway.
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Affiliation(s)
- Hoon-Seong Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Mi-Ji Lee
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Sheu-Ran Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea
| | - Branden A Smeester
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN, USA
| | - Alvin J Beitz
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN, USA
| | - Jang-Hern Lee
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.
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5
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Robarge JD, Duarte DB, Shariati B, Wang R, Flockhart DA, Vasko MR. Aromatase inhibitors augment nociceptive behaviors in rats and enhance the excitability of sensory neurons. Exp Neurol 2016; 281:53-65. [PMID: 27072527 DOI: 10.1016/j.expneurol.2016.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/28/2016] [Accepted: 04/05/2016] [Indexed: 12/22/2022]
Abstract
Although aromatase inhibitors (AIs) are commonly used therapies for breast cancer, their use is limited because they produce arthralgia in a large number of patients. To determine whether AIs produce hypersensitivity in animal models of pain, we examined the effects of the AI, letrozole, on mechanical, thermal, and chemical sensitivity in rats. In ovariectomized (OVX) rats, administering a single dose of 1 or 5mg/kg letrozole significantly reduced mechanical paw withdrawal thresholds, without altering thermal sensitivity. Repeated injection of 5mg/kg letrozole in male rats produced mechanical, but not thermal, hypersensitivity that extinguished when drug dosing was stopped. A single dose of 5mg/kg letrozole or daily dosing of letrozole or exemestane in male rats also augmented flinching behavior induced by intraplantar injection of 1000nmol of adenosine 5'-triphosphate (ATP). To determine whether sensitization of sensory neurons contributed to AI-induced hypersensitivity, we evaluated the excitability of neurons isolated from dorsal root ganglia of male rats chronically treated with letrozole. Both small and medium-diameter sensory neurons isolated from letrozole-treated rats were more excitable, as reflected by increased action potential firing in response to a ramp of depolarizing current, a lower resting membrane potential, and a lower rheobase. However, systemic letrozole treatment did not augment the stimulus-evoked release of the neuropeptide calcitonin gene-related peptide (CGRP) from spinal cord slices, suggesting that the enhanced nociceptive responses were not secondary to an increase in peptide release from sensory endings in the spinal cord. These results provide the first evidence that AIs modulate the excitability of sensory neurons, which may be a primary mechanism for the effect of these drugs to augment pain behaviors in rats.
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Affiliation(s)
- Jason D Robarge
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States; Department of Medicine, Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - Djane B Duarte
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States; Laboratório de Farmacologia Molecular, Faculdade de Ciências da Saúde, Universidade de Brasília, Brazil.
| | - Behzad Shariati
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - Ruizhong Wang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - David A Flockhart
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States; Department of Medicine, Division of Clinical Pharmacology, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - Michael R Vasko
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States.
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6
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Boadas-Vaello P, Castany S, Homs J, Álvarez-Pérez B, Deulofeu M, Verdú E. Neuroplasticity of ascending and descending pathways after somatosensory system injury: reviewing knowledge to identify neuropathic pain therapeutic targets. Spinal Cord 2016; 54:330-40. [DOI: 10.1038/sc.2015.225] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 11/25/2015] [Accepted: 11/28/2015] [Indexed: 12/16/2022]
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Abstract
In recent years, studies have substantiated the view that P2X3 receptors play a part in the generation and transmission of purinergic signals in inflammatory and chronic neuropathic pain. Data have also been presented to suggest that the process of P2X3 receptor antagonism inhibits inflammatory hyperalgesia, involving the spinal opioid system. The aim of this study was to investigate the effect of the selective P2X3 receptor antagonist A-317491 on the development of antinociceptive tolerance to chronic morphine administration in mice. Daily systemic injection of A-317491 attenuated the morphine-induced antinociceptive tolerance to von Frey and thermal stimuli. Repeated morphine injections alone led to a significant rightward shift in the morphine dose-response curve compared with that with A-317491. A single dose of A-317491 also showed a reversal effect in morphine-tolerant mice. In a withdrawal test, co-administration of A-317491 and morphine also reduced the naloxone-induced withdrawal symptoms compared with the morphine-alone group. Thus, we propose that the P2X3 receptor is involved in the process of morphine antinociceptive tolerance and may be a new therapeutic target in the prevention of tolerance to morphine-induced antinociception.
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8
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Bravo D, Maturana CJ, Pelissier T, Hernández A, Constandil L. Interactions of pannexin 1 with NMDA and P2X7 receptors in central nervous system pathologies: Possible role on chronic pain. Pharmacol Res 2015. [PMID: 26211949 DOI: 10.1016/j.phrs.2015.07.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Pannexin 1 (Panx1) is a glycoprotein that acts as a membrane channel in a wide variety of tissues in mammals. In the central nervous system (CNS) Panx1 is expressed in neurons, astrocytes and microglia, participating in the pathophysiology of some CNS diseases, such as epilepsy, anoxic depolarization after stroke and neuroinflammation. In these conditions Panx1 acts as an important modulator of the neuroinflammatory response, by secreting ATP, by interacting with the P2X7 receptor (P2X7R), and as an amplifier of NMDA receptor (NMDAR) currents, particularly in conditions of pathological neuronal hyperexcitability. Here, we briefly reviewed the current evidences that support the interaction of Panx1 with NMDAR and P2X7R in pathological contexts of the CNS, with special focus in recent data supporting that Panx1 is involved in chronic pain signaling by interacting with NMDAR in neurons and with P2X7R in glia. The participation of Panx1 in chronic pain constitutes a novel topic for research in the field of clinical neurosciences and a potential target for pharmacological interventions in chronic pain.
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Affiliation(s)
- D Bravo
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Chile; School of Kinesiology, Faculty of Sport, Health and Recreation, University Bernardo O'Higgins, Chile.
| | - C J Maturana
- Departamento de Fisiología, Pontificia Universidad Católica De Chile, Chile
| | - T Pelissier
- Program of Molecular and Clinical Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Chile
| | - A Hernández
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Chile
| | - L Constandil
- Laboratory of Neurobiology, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Chile
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Guo X, Chen J, Lu Y, Wu L, Weng Z, Yang L, Xin Y, Lin X, Liang Y, Fang J. Electroacupuncture at He-Mu points reduces P2X4 receptor expression in visceral hypersensitivity. Neural Regen Res 2014; 8:2069-77. [PMID: 25206515 PMCID: PMC4146068 DOI: 10.3969/j.issn.1673-5374.2013.22.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 07/08/2013] [Indexed: 01/30/2023] Open
Abstract
Electroacupuncture at Shangjuxu (ST37) and Tianshu (ST25) was reported to improve visceral hypersensitivity in rats. Colorectal distension was utilized to generate a rat model of chronic visceral hypersensitivity in irritable bowel syndrome. Results showed that abdominal withdrawal reflex scores noticeably increased after model establishment. Simultaneously, P2X4 receptor immureactivity significantly increased in the colon and spinal cord. Electroacupuncture and pinaverium bromide therapy both markedly decreased abdominal withdrawal reflex scores in rats with visceral hypersensitivity, and significantly decreased P2X4 receptor immunoreactivity in the colon and spinal cord. These data suggest that electroacupuncture treatment can improve visceral hypersensitivity in rats with irritable bowel syndrome by diminishing P2X4 receptor immunoreactivity in the colon and spinal cord.
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Affiliation(s)
- Xinxin Guo
- Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, Zhejiang Province, China
| | - Jifei Chen
- Department of Orthopedics, Zhongshan Hospital of Fudan University, Shanghai 200032, China
| | - Yuan Lu
- Shanghai Institute for Traditional Chinese Medicine, Shanghai 201203, China
| | - Luyi Wu
- Shanghai Institute for Traditional Chinese Medicine, Shanghai 201203, China
| | - Zhijun Weng
- Shanghai Institute for Traditional Chinese Medicine, Shanghai 201203, China
| | - Ling Yang
- Shanghai Institute for Traditional Chinese Medicine, Shanghai 201203, China
| | - Yuhu Xin
- Cancer Hospital, Fudan University, Shanghai 200032, China
| | - Xianming Lin
- Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, Zhejiang Province, China
| | - Yi Liang
- Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, Zhejiang Province, China
| | - Jianqiao Fang
- Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou 310005, Zhejiang Province, China
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Li L, Luo R, Fan P, Guo Y, Wang HS, Ma SJ, Zhao Y. Role of peripheral purinoceptors in the development of bee venom-induced nociception: a behavioural and electrophysiological study in rats. Clin Exp Pharmacol Physiol 2014; 41:902-10. [PMID: 25115823 DOI: 10.1111/1440-1681.12293] [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: 02/21/2014] [Revised: 06/18/2014] [Accepted: 07/29/2014] [Indexed: 11/29/2022]
Abstract
Colocalization of purinergic P2X and P2Y receptors in dorsal root ganglion sensory neurons implies that these receptors play an integrative role in the nociceptive transmission process under inflammatory conditions. In the present study, behavioural and in vivo electrophysiological methods were used to examine the peripheral role of P2 receptors in the persistent nociceptive responses induced by subcutaneous bee venom injection (2 mg/mL) in. Sprague-Dawley rats Local pretreatment with the wide-spectrum P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS; 1 mmol/L, 50 μL) 10 min prior to s.c. bee venom injection significantly suppressed the duration of spontaneous nociceptive lifting/licking behaviour, inhibited mechanical hyperalgesia and decreased the firing of spinal dorsal horn wide dynamic range neurons in response to bee venom, without affecting primary thermal and mirror-image hyperalgesia. The localized antinociceptive action of PPADS was not due to a systemic effect, because application of the same dose of PPADS to the contralateral side was not effective. The results suggest that activation of peripheral P2 receptors is involved in the induction of nociceptive responses, mechanical hyperalgesia and the excitation of sensory spinal neurons.
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Affiliation(s)
- Li Li
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University Health Science Center, Xi'an, China
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Hasebein P, Frehland B, Schepmann D, Wünsch B. Synthesis, σ Receptor Affinity, and Pharmacological Evaluation of 5-Phenylsulfanyl- and 5-Benzyl-Substituted Tetrahydro-2-benzazepines. ChemMedChem 2014; 9:1697-703. [DOI: 10.1002/cmdc.201402110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Indexed: 11/06/2022]
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Segawa T, Miyakoshi N, Kasukawa Y, Aonuma H, Tsuchie H, Shimada Y. Analgesic effects of minodronate on formalin-induced acute inflammatory pain in rats. Biomed Res 2014; 34:137-41. [PMID: 23782747 DOI: 10.2220/biomedres.34.137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Minodronate is expected to produce greater analgesic effects than other bisphosphonates. However, there are no studies comparing bisphosphonate analgesic effects on formalin-induced acute inflammatory pain in rats. The purpose of the present study was to evaluate the analgesic effects of minodronate, morphine, and placebo. Four-month-old female Wistar rats were administered minodronate (50 mg/kg), morphine (10 mg/kg), or vehicle (n = 10 each) injections. Thirty minutes later, all rats were injected with formalin (right hind paw) to induce acute inflammatory pain. Paw licking and lifting as indicators of nociceptive pain responses were monitored from 0 to 5 min (phase 1; chemical-stimulation state) and then from 10 to 30 min (phase 2; spinal-sensitized state) after injection. The percentage of limb usage of the formalin-injected and the non-injected sides were measured in phases 1 and 2 by counting foot stamps. Minodronate significantly decreased nociceptive responses and increased limb usage compared with vehicle in phase 2 only (P < 0.05). Morphine significantly decreased nociceptive responses and increased limb usage compared with minodronate and vehicle in both phase 1 and 2 (P < 0.05). In conclusion, minodronate showed significant analgesic effects for formalin-induced acute pain in the spinal-sensitized state.
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Affiliation(s)
- Toyohito Segawa
- Department of Orthopedic Surgery, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan.
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Neurogenic neuroinflammation: inflammatory CNS reactions in response to neuronal activity. Nat Rev Neurosci 2013; 15:43-53. [PMID: 24281245 DOI: 10.1038/nrn3617] [Citation(s) in RCA: 378] [Impact Index Per Article: 34.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The CNS is endowed with an elaborated response repertoire termed 'neuroinflammation', which enables it to cope with pathogens, toxins, traumata and degeneration. On the basis of recent publications, we deduce that orchestrated actions of immune cells, vascular cells and neurons that constitute neuroinflammation are not only provoked by pathological conditions but can also be induced by increased neuronal activity. We suggest that the technical term 'neurogenic neuroinflammation' should be used for inflammatory reactions in the CNS in response to neuronal activity. We believe that neurogenic neuro-inflammation maintains homeostasis to enable the CNS to cope with enhanced metabolic demands and increases the computational power and plasticity of CNS neuronal networks. However, neurogenic neuroinflammation may also become maladaptive and aggravate the outcomes of pain, stress and epilepsy.
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New approaches to thyroid hormones and purinergic signaling. J Thyroid Res 2013; 2013:434727. [PMID: 23956925 PMCID: PMC3730180 DOI: 10.1155/2013/434727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/20/2013] [Indexed: 12/22/2022] Open
Abstract
It is known that thyroid hormones influence a wide variety of events at the molecular, cellular, and functional levels. Thyroid hormones (TH) play pivotal roles in growth, cell proliferation, differentiation, apoptosis, development, and metabolic homeostasis via thyroid hormone receptors (TRs) by controlling the expression of TR target genes. Most of these effects result in pathological and physiological events and are already well described in the literature. Even so, many recent studies have been devoted to bringing new information on problems in controlling the synthesis and release of these hormones and to elucidating mechanisms of the action of these hormones unconventionally. The purinergic system was recently linked to thyroid diseases, including enzymes, receptors, and enzyme products related to neurotransmitter release, nociception, behavior, and other vascular systems. Thus, throughout this text we intend to relate the relationship between the TH in physiological and pathological situations with the purinergic signaling.
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Kumar N, Cherkas PS, Chiang CY, Dostrovsky JO, Sessle BJ, Coderre TJ. Involvement of ATP in noxious stimulus-evoked release of glutamate in rat medullary dorsal horn: a microdialysis study. Neurochem Int 2012; 61:1276-9. [PMID: 23079194 DOI: 10.1016/j.neuint.2012.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 10/05/2012] [Accepted: 10/07/2012] [Indexed: 10/27/2022]
Abstract
Our electrophysiological studies have shown that both purinergic and glutamatergic receptors are involved in central sensitization of nociceptive neurons in the medullary dorsal horn (MDH). Here we assessed the effects of intrathecal administration of apyrase (a nucleotide degrading enzyme of endogenous adenosine 5-triphosphate [ATP]), a combination of apyrase and 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, an adenosine A1 receptor antagonist), or 2,3-O-2,4,6-trinitrophenyl-adenosine triphosphate (TNP-ATP, a P2X1, P2X3, P2X2/3 receptor antagonist) on the release of glutamate in the rat MDH evoked by application of mustard oil (MO) to the molar tooth pulp. In vivo microdialysis was used to dialyse the MDH every 5 min, and included 3 basal samples, 6 samples after drug treatment and 12 samples following application of MO. Tooth pulp application of MO induced a significant increase in glutamate release in the MDH. Superfusion of apyrase or TNP-ATP alone significantly reduced the MO-induced glutamate release in the MDH, as compared to vehicle. Furthermore, the suppressive effects of apyrase on glutamate release were reduced by combining it with DPCPX. This study demonstrates that application of an inflammatory irritant to the tooth pulp induces glutamate release in the rat MDH in vivo that may be reduced by processes involving endogenous ATP and adenosine.
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Affiliation(s)
- Naresh Kumar
- Alan Edwards Centre for Research on Pain, Dept. of Anesthesia, McGill University, Montreal, QC H3G 1Y6, Canada
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Ford AP. P2X3 antagonists: novel therapeutics for afferent sensitization and chronic pain. Pain Manag 2012; 2:267-77. [DOI: 10.2217/pmt.12.16] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
SUMMARY Despite decades of innovation and effort, the pharmaceutical needs of countless patients with chronic pain remain underserved. Effective and safe treatments must clearly come from novel approaches, yet targets and molecules selected hitherto have returned little benefit. Antagonism of P2X3 purinoceptors on pain-conveying nerves is a highly novel approach, and compounds from this class are advancing into patient studies. P2X3 channels are found in C- and Aδ-primary afferent neurons in most tissues, and are strikingly specific to pain detection. P2X3 antagonists block peripheral activation of these fibers via ATP, released from most cells by inflammation, injury, stress and distension, and clearly provide an alternative pharmacological mechanism to attenuate pain signals. P2X3 is also expressed presynaptically at central spinal terminals of afferent neurons, where ATP further sensitizes painful signals en route to the brain. The selectivity of P2X3 expression allows hope of a lower potential for adverse effects in brain, gut and cardiovascular tissues – limiting factors for most analgesics. P2X3 receptor-mediated sensitization has been implicated in rodent models in inflammatory, visceral, neuropathic and cancer pain states, as well as in airways hyper-reactivity, migraine and visceral organ irritability. Although we are often reminded that the effects of new medicines can translate poorly into clinical effectiveness, the broad efficacy seen following P2X3 inhibition in rodent models strengthens the prospect that an unprecedented mechanism to counter sensitization of afferent pathways may offer some merciful relief to millions of patients struggling daily with persistent discomfort and pain.
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Affiliation(s)
- Anthony P Ford
- Afferent Pharmaceuticals, 2755 Campus Drive, Suite 100, San Mateo, CA 94403, USA
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17
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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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SATO KAORUTAKAHASHI, SATOH KOICHIRO, SEKIGUCHI MIHO, KIKUCHI SHINICHI, KONNO SHINICHI, MURAKAWA MASAHIRO, RYDEVIK BJ, OLMARKER KJELL. LOCAL APPLICATION OF NUCLEUS PULPOSUS INDUCES EXPRESSION OF P2X3 IN RAT DORSAL ROOT GANGLION CELLS. Fukushima J Med Sci 2012; 58:17-21. [DOI: 10.5387/fms.58.17] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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19
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In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization. Purinergic Signal 2011; 8:3-26. [PMID: 22095157 PMCID: PMC3265711 DOI: 10.1007/s11302-011-9271-6] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/19/2011] [Indexed: 12/20/2022] Open
Abstract
Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention.
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Ballini E, Virginio C, Medhurst SJ, Summerfield SG, Aldegheri L, Buson A, Carignani C, Chen YH, Giacometti A, Lago I, Powell AJ, Jarolimek W. Characterization of three diaminopyrimidines as potent and selective antagonists of P2X3 and P2X2/3 receptors with in vivo efficacy in a pain model. Br J Pharmacol 2011; 163:1315-25. [PMID: 21410458 DOI: 10.1111/j.1476-5381.2011.01322.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE P2X3 and P2X2/3 receptors are highly localized on the peripheral and central pathways of nociceptive signal transmission. The discovery of A-317491 allowed their validation as chronic inflammatory and neuropathic pain targets, but this molecule has a very limited oral bioavailability and CNS penetration. Recently, potent P2X3 and P2X2/3 blockers with a diaminopyrimidine core group and better bioavailability were synthesized and represent a new opportunity for the validation of P2X3-containing receptors as targets for pain. Here we present a characterization of three representative diaminopyrimidines. EXPERIMENTAL APPROACH The activity of compounds was evaluated in intracellular calcium flux and electrophysiological recordings from P2X receptors expressed in mammalian cells and in a in vivo model of inflammatory pain (complete Freund's adjuvant (CFA) in rat paws). KEY RESULTS Compound A potently blocked P2X3 (pIC(50)= 7.39) and P2X2/3 (pIC(50)=6.68) and showed no detectable activity at P2X1, P2X2, P2X4 and P2X7 receptors (pIC(50)< 4.7). Whole-cell voltage clamp electrophysiology confirmed these results. Compounds showed good selectivities when tested against a panel of different classes of target. In the CFA model, compound B showed significant anti-nociceptive effects (57% reversal at 3mg·kg(-1) ). CONCLUSIONS AND IMPLICATIONS The diaminopyrimidines were potent and selective P2X3 and P2X2/3 receptor antagonists, showing efficacy in vivo and represent useful tools to validate these receptors as targets for inflammatory and neuropathic pain and provide promising progress in the identification of therapeutic tools for the treatment of pain-related disorders.
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Affiliation(s)
- E Ballini
- GlaxoSmithKline, Molecular Discovery Research, Verona, Italy.
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21
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Borsani E, Albertini R, Labanca M, Lonati C, Rezzani R, Rodella LF. Peripheral purinergic receptor modulation influences the trigeminal ganglia nitroxidergic system in an experimental murine model of inflammatory orofacial pain. J Neurosci Res 2011; 88:2715-26. [PMID: 20648657 DOI: 10.1002/jnr.22420] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
ATP plays an important role as an endogenous pain mediator generating and/or modulating pain signaling from the periphery to the central nervous system. The aim of this study was to analyze the role of peripheral purinergic receptors in modulation of the nitroxidergic system at a trigeminal ganglia level by monitoring changes in nitric oxide synthase isoforms. We also evaluated Fos-positive neurons in brainstem (spinal trigeminal nucleus) and pain-related behavior. We found that local administration of the P2 purinergic receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) decreased face-rubbing activity, nitric oxide synthase isoform expression in trigeminal ganglia, and Fos expression in spinal trigeminal nucleus after subcutaneous injection of formalin. These results suggest a role for peripheral P2 purinergic receptors in orofacial pain transmission through modulation of the nitroxidergic system. .
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Affiliation(s)
- Elisa Borsani
- Division of Human Anatomy, Department of Biomedical Sciences and Biotechnologies, Brescia University, 25123 Brescia, Italy
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Zhang H, Liu L, Lu G, Chen Z, Fang Q, Yang Z, Li L, Li W, Song B, Zhou Z. Chemical irritation of the prostate sensitizes P(2)X(3) receptor-mediated responses in rat dorsal root ganglion neurons. Neurourol Urodyn 2011; 30:612-8. [PMID: 21254200 DOI: 10.1002/nau.21060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 12/13/2010] [Indexed: 11/07/2022]
Abstract
AIMS P(2)X(3) (ATP-gated receptors) in nociceptive neurons of dorsal root ganglion (DRG) participate in transmission of pain signals from the periphery to the spinal cord. However, the role of P(2)X(3) receptors in chronic prostate pain and continued intractable pain remains unclear. MATERIALS AND METHODS We examined ATP-evoked responses and P(2)X(3) expression in DRG neurons isolated from rats with prostatic inflammation induced by injection of complete Freund's adjuvant (CFA) into the prostate. Neurons were dissociated from the L(6)-S(1) DRG. The effect of ATP on the excitability of DRG neurons was determined using whole-cell patch clamp. P(2)X(3) receptor expression was determined with Western blot on the 3rd and 10th days after irritation of the prostate. RESULTS Although application of ATP induced both fast- and slow-inactivating currents and caused depolarization in control and inflamed neurons, compared to the control group, the increase in ATP responses gave rise to large depolarization that exceeded the threshold of action potentials in inflamed DRG neurons. The affinity of P(2)X(3) receptor for ATP increased significantly and inflammation enhanced the expression of P(2)X(3) receptor in inflamed neurons. CONCLUSIONS P(2)X(3) receptor upregulation could account for neuronal hypersensitivity and contribute to abnormal pain responses associated with chronic prostatitis. These results suggest that P(2)X(3) receptors are useful targets for the treatment of pain in chronic prostatitis.
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Affiliation(s)
- Heng Zhang
- Department of Urology, Southwest Hospital, Third Military Medical University, Chongqing, China
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23
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Abstract
The pharmacological concept of specifically targeting purinoceptors (receptors for ATP and related nucleotides) has emerged over the last two decades in the quest for novel, differentiated therapeutics. Investigations from many laboratories have established a prominent role for ATP in the functional regulation of most tissue and organ systems, including the urinary tract, under normal and pathophysiological conditions. In the particular case of the urinary tract, ATP signaling via P2X1 receptors participates in the efferent control of detrusor smooth muscle excitability, and this function may be heightened in disease and aging. Perhaps of greater interest, ATP also appears to be involved in bladder sensation, operating via activation of P2X3-containing receptors on sensory afferent neurones, both on peripheral terminals within the urinary tract tissues (e.g., ureters, bladder) and on central synapses in the dorsal horn of the spinal cord. Such findings are based on results from classical pharmacological and localization studies in nonhuman and human tissues, gene knockout mice, and studies using recently identified pharmacological antagonists - some of which have progressed as candidate drug molecules. Based on recent advances in this field, it is apparent that the development of selective antagonists for these receptors will occur that could lead to therapies offering better relief of storage, voiding, and sensory symptoms for patients, while minimizing the systemic side effects that curb the clinical effectiveness of current urologic medicines.
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Hatanaka J, Shinme Y, Kuriyama K, Uchida A, Kou K, Uchida S, Yamada S, Onoue S. In vitro and in vivo Characterization of New Formulations of St. John's Wort Extract with Improved Pharmacokinetics and Anti-nociceptive Effect. Drug Metab Pharmacokinet 2011; 26:551-8. [DOI: 10.2133/dmpk.dmpk-11-rg-041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Endogenous purinergic control of bladder activity via presynaptic P2X3 and P2X2/3 receptors in the spinal cord. J Neurosci 2010; 30:4503-7. [PMID: 20335487 DOI: 10.1523/jneurosci.6132-09.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
P2X(3) and P2X(2/3) receptors are localized on sensory afferents both peripherally and centrally and have been implicated in various sensory functions. However, the physiological role of these receptors expressed presynaptically in the spinal cord in regulating sensory transmission remains to be elucidated. Here, a novel selective P2X(3) and P2X(2/3) antagonist, AF-792 [5-(5-ethynyl-2-isopropyl-4-methoxy-phenoxy)-pyrimidine-2,4-diamine, previously known as RO-5], in addition to less selective purinoceptor ligands, was applied intrathecally in vivo. Cystometry recordings were made to assess changes in the micturition reflex contractions after drug treatments. We found that AF-792 inhibited micturition reflex activity significantly (300 nmol; from baseline contraction intervals of 1.18 +/- 0.07 to 9.33 +/- 2.50 min). Furthermore, inhibition of P2X(3) and P2X(2/3) receptors in the spinal cord significantly attenuated spinal activation of extracellular-signal regulated kinases induced by acute peripheral stimulation of the bladder with 1% acetic acid by 46.4 +/- 12.0% on average. Hence, the data suggest that afferent signals originating from the bladder are regulated by spinal P2X(3) and P2X(2/3) receptors and establish directly an endogenous central presynaptic purinergic mechanism to regulate visceral sensory transmission. Identification of this spinal purinergic control in visceral activities may help the development of P2X(3) and P2X(2/3) antagonist to treat urological dysfunction, such as overactive bladder, and possibly other debilitating sensory disorders, including chronic pain states.
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Ohnishi T, Matsumura S, Ito S. Translocation of neuronal nitric oxide synthase to the plasma membrane by ATP is mediated by P2X and P2Y receptors. Mol Pain 2009; 5:40. [PMID: 19619286 PMCID: PMC3224951 DOI: 10.1186/1744-8069-5-40] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 07/20/2009] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND The translocation of neuronal nitric oxide synthase (nNOS) from the cytosol to the membrane is functionally coupled to the activation of N-methyl-D-aspartate (NMDA) receptors at synapses. Whereas there is abundant evidence indicating that ATP and nitric oxide are involved in nociceptive transmission, whether nNOS is activated by ATP remains unknown. We recently established a fluorescence imaging system for examining nNOS translocation in PC12 cells expressing a yellow fluorescence protein-tagged nNOS N-terminal mutant, nNOSNT-YFP, and examined the effect of ATP on nNOS translocation using the system. RESULTS The translocation of nNOS was induced by ATP in the presence of NMDA and forskolin, an adenylate cyclase activator. The purinergic P2X receptor agonist 2-MeSATP and the P2Y agonist UTP significantly enhanced nNOS translocation; and simultaneous stimulation with 2-MeSATP and UTP exhibited the same concentration-response curve for the translocation as obtained with ATP. ATP, 2-MeSATP, and UTP increased the intracellular Ca2+ concentration ([Ca2+]i) in PC12 cells. Conversely, whereas the P2X receptor antagonist PPADS and the P2Y antagonist reactive blue-2 partially inhibited increases in the translocation of nNOS and [Ca2+]i by ATP, the non-selective P2 receptor antagonist suramin completely blocked them. In addition, the increase in the nNOS translocation by ATP was blocked by NMDA receptor antagonists and inhibitors of protein kinase A, protein kinase C, and Src kinase. Consistent with the expression of P2X and P2Y receptors in the spinal cord, ATP and UTP increased the [Ca2+]i in primary cultured spinal neurons. ATP potentiated and prolonged the [Ca2+]i increase produced by NMDA in the dorsal horn of the spinal cord. Furthermore, the selective P2X3/P2X2/3 antagonist A-317491 inhibited nNOS activation assessed by NO formation in spinal slices prepared from neuropathic pain model mice. CONCLUSION ATP is involved in nNOS translocation mediated by protein kinase C via activation of P2X and P2Y receptors and nNOS translocation may be an action mechanism of ATP in nocieptive processing in the spinal cord.
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Affiliation(s)
- Takayuki Ohnishi
- Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono, Moriguchi 570-8506, Japan
- Current address : Division of Pharmacology, Molecular and Cellular Medicine, Niigata University, Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan
| | - Shinji Matsumura
- Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono, Moriguchi 570-8506, Japan
| | - Seiji Ito
- Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono, Moriguchi 570-8506, Japan
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Behavioral phenotypes of mice lacking purinergic P2X4 receptors in acute and chronic pain assays. Mol Pain 2009; 5:28. [PMID: 19515262 PMCID: PMC2704200 DOI: 10.1186/1744-8069-5-28] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 06/11/2009] [Indexed: 12/14/2022] Open
Abstract
A growing body of evidence indicates that P2X receptors (P2XRs), a family of ligand-gated cation channels activated by extracellular ATP, play an important role in pain signaling. In contrast to the role of the P2X3R subtype that has been extensively studied, the precise roles of others among the seven P2XR subtypes (P2X1R-P2X7R) remain to be determined because of a lack of sufficiently powerful tools to specifically block P2XR signaling in vivo. In the present study, we investigated the behavioral phenotypes of a line of mice in which the p2rx4 gene was disrupted in a series of acute and chronic pain assays. While p2rx4-/- mice showed no major defects in pain responses evoked by acute noxious stimuli and local tissue damage or in motor function as compared with wild-type mice, these mice displayed reduced pain responses in two models of chronic pain (inflammatory and neuropathic pain). In a model of chronic inflammatory pain developed by intraplantar injection of complete Freund's adjuvant (CFA), p2rx4-/- mice exhibited attenuations of pain hypersensitivity to innocuous mechanical stimuli (tactile allodynia) and also of the CFA-induced swelling of the hindpaw. A most striking phenotype was observed in a test of neuropathic pain: tactile allodynia caused by an injury to spinal nerve was markedly blunted in p2rx4-/- mice. By contrast, pain hypersensitivity to a cold stimulus (cold allodynia) after the injury was comparable in wild-type and p2rx4-/- mice. Together, these findings reveal a predominant contribution of P2X4R to nerve injury-induced tactile allodynia and, to the lesser extent, peripheral inflammation. Loss of P2X4R produced no defects in acute physiological pain or tissue damaged-induced pain, highlighting the possibility of a therapeutic benefit of blocking P2X4R in the treatment of chronic pain, especially tactile allodynia after nerve injury.
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Abstract
Hyperalgesia and allodynia are frequent symptoms of disease and may be useful adaptations to protect vulnerable tissues. Both may, however, also emerge as diseases in their own right. Considerable progress has been made in developing clinically relevant animal models for identifying the most significant underlying mechanisms. This review deals with experimental models that are currently used to measure (sect. II) or to induce (sect. III) hyperalgesia and allodynia in animals. Induction and expression of hyperalgesia and allodynia are context sensitive. This is discussed in section IV. Neuronal and nonneuronal cell populations have been identified that are indispensable for the induction and/or the expression of hyperalgesia and allodynia as summarized in section V. This review focuses on highly topical spinal mechanisms of hyperalgesia and allodynia including intrinsic and synaptic plasticity, the modulation of inhibitory control (sect. VI), and neuroimmune interactions (sect. VII). The scientific use of language improves also in the field of pain research. Refined definitions of some technical terms including the new definitions of hyperalgesia and allodynia by the International Association for the Study of Pain are illustrated and annotated in section I.
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Affiliation(s)
- Jürgen Sandkühler
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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Reitz M, Makowska A, Ellrich J. Excitatory and inhibitory purinergic control of neck muscle nociception in anaesthetized mice. Cephalalgia 2009; 29:58-67. [PMID: 19126119 DOI: 10.1111/j.1468-2982.2008.01700.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tension-type headache is associated with noxious input from neck muscles. Due to the importance of purinergic mechanisms in muscle nociception, experimental studies typically inject alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-meATP). In contrast to native adenosine 5'-triphosphate (ATP), alpha,beta-meATP has a narrow receptor profile and remains stable in tissue. The present study administered alpha,beta-meATP or ATP in semi-spinal neck muscles in anaesthetized mice (n = 65) in order to address different effects in neck muscle nociception. The jaw-opening reflex monitored the impact of neck muscle noxious input on brainstem processing. Injection of alpha,beta-meATP induced reflex facilitation in a dose-dependent manner. In contrast, only the lowest ATP dosage evoked facilitation. Preceding P2Y(1) receptor blockade revealed facilitation even under high-dosage ATP. Ongoing facilitation after alpha,beta-meATP injection neutralized under subsequent activation of P2Y(1) receptors. Results demonstrate opposing excitatory P2X and inhibitory P2Y effects of ATP in neck muscle nociception. These mechanisms may be involved in the pathophysiology of neck muscle pain in man.
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Affiliation(s)
- M Reitz
- Experimental Neurosurgery Section, Department of Neurosurgery, Medical Faculty, RWTH Aachen University, Aachen, Germany
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30
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Tsai TL, Chang SY, Ho CY, Kou YR. Role of ATP in the ROS-mediated laryngeal airway hyperreactivity induced by laryngeal acid-pepsin insult in anesthetized rats. J Appl Physiol (1985) 2009; 106:1584-92. [PMID: 19246655 DOI: 10.1152/japplphysiol.91517.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pathogenetic mechanisms of laryngeal airway hyperreactivity (LAH) in patients with extraesophageal reflux are unclear. We recently reported that a laryngeal acid-pepsin insult produces LAH that is mediated through sensitization of the capsaicin-sensitive laryngeal afferent fibers by reactive oxygen species (ROS) in rats. Since ROS may promote the release of ATP from cells, we hypothesized that activation of P2X purinoceptors by ATP subsequent to an increase in ROS induces LAH in an inflamed larynx that has been insulted by acid-pepsin or H(2)O(2) (a major type of ROS). The larynxes of 208 anesthetized rats were functionally isolated while the animals breathed spontaneously. Ammonia vapor was delivered into the larynx to measure laryngeal reflex reactivity. Laryngeal insult with acid-pepsin or H(2)O(2) produced LAH with similar characteristics. The H(2)O(2)-induced LAH was prevented by laryngeal pretreatment with dimethylthiourea (a hydroxyl radical scavenger), suggesting a critical role for ROS. The LAH induced by both insults were completely prevented by ATP scavengers (a combination of apyrase and adenosine deaminase) or a P2X receptor antagonist (iso-pyridoxalphosphate-6-azophenyl-2',5'-disulfonate). Laryngeal application of a P2X receptor agonist (alpha,beta-methylene-ATP) also produced LAH. An insult with either acid-pepsin or H(2)O(2) similarly promoted an increase in the levels of ATP, lipid peroxidation, and inflammation in the larynx. Our findings suggest that laryngeal insult with acid-pepsin or H(2)O(2) induces inflammation and produces excess ROS in the rat's larynx. The latter may in turn promote the release of ATP to activate P2X receptors, resulting in sensitization of capsaicin-sensitive laryngeal afferent fibers and LAH.
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Affiliation(s)
- Tung-Lung Tsai
- Institute of Physiology, School of Medicine, National Yang-Ming Univ., Taipei 11221, Taiwan
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31
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Jarvis MF, Khakh BS. ATP-gated P2X cation-channels. Neuropharmacology 2008; 56:208-15. [PMID: 18657557 DOI: 10.1016/j.neuropharm.2008.06.067] [Citation(s) in RCA: 259] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 06/24/2008] [Accepted: 06/30/2008] [Indexed: 12/20/2022]
Abstract
P2X receptors are ATP-gated cation channels with important roles in diverse pathophysiological processes. Substantial progress has been made in the last few years with the discovery of both subunit selective antagonists and modulators. The purpose of this brief review is to summarize the advances in the pharmacology of P2X receptors, with key properties presented in an easy to access format. Ligand-gated ion channels consist of three families in mammals; the ionotropic glutamate receptors, the Cys-loop receptors (for GABA, ACh, glycine and serotonin) and the P2X receptors for ATP. The first two of these are considered in articles accompanying this Special Issue. Here we consider the pharmacological properties of P2X receptors. We do not present a detailed discussion of P2X receptor physiological roles or structure-function studies. Moreover, the pharmacological basis for discriminating between the main subtypes of P2X receptor and their nomenclature has been published by the Nomenclature Committee of the International Union of Pharmacology (NC-IUPHAR) P2X Receptor Subcommittee, and so these aspects are not revisited here. Instead in this brief article we seek to present a summary of the pharmacology of recombinant homomeric and heteromeric P2X receptors, with particular emphasis on new antagonists. In this article we have tried to present as much information as possible in two tables in the hope this will be useful as a day-to-day resource, and also because an excellent and detailed review has recently been published.
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Affiliation(s)
- Michael F Jarvis
- Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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Minodronic acid, a third-generation bisphosphonate, antagonizes purinergic P2X(2/3) receptor function and exerts an analgesic effect in pain models. Eur J Pharmacol 2008; 589:98-101. [PMID: 18565509 DOI: 10.1016/j.ejphar.2008.05.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 04/15/2008] [Accepted: 05/13/2008] [Indexed: 01/01/2023]
Abstract
The P2X(2/3) receptor has an important role in the nociceptive transmission. Minodronic acid is a third third-generation bisphosphonate and a potent inhibitor of bone resorption. We found that minodronic acid inhibited alpha,beta-methylene ATP-induced cation uptake with the potency higher than that of suramin in the P2X(2/3) receptor receptor-expressing cells. Other bisphosphonates did not show such activity. Subcutaneously administered (10-50 mg/kg) minodronic acid significantly inhibited the alpha,beta-methylene ATP-, acetic acid- and formalin-induced nociceptive behaviors in mice. These unique effects of minodronic acid would be beneficial for the treatment of accelerated bone turnover diseases accompanied by bone pain, including bone metastases.
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Uchida S, Hirai K, Hatanaka J, Hanato J, Umegaki K, Yamada S. Antinociceptive effects of St. John's wort, Harpagophytum procumbens extract and Grape seed proanthocyanidins extract in mice. Biol Pharm Bull 2008; 31:240-5. [PMID: 18239280 DOI: 10.1248/bpb.31.240] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypericum perforatum extract (St. John's wort, SJW), Harpagophytum procumbens extract (HPE) and Grape seed proanthocyanidin extract (GSPE) have a broad spectrum of biological activities including antidepressant, anti-inflammatory or anti-oxidant effects. The aim of this study was to clarify antinociceptive properties of SJW, HPE and GSPE in mice with mechanisms that might potentially underlie these activities. Also, the effects of these herbal extracts on the antinociception and plasma and brain concentrations of morphine were examined. Oral pretreatment with SJW (100-1000 mg/kg) and HPE (30-300 mg/kg) attenuated significantly times of licking/biting both first and second phases of formalin injection in mice in the dose-dependent manner, and GSPE (10-300 mg/kg) suppressed second phase. Naloxone (5 mg/kg, s.c.) significantly attenuated antinociceptive effect of HPE but not SJW and GSPE. Formalin injection resulted in significant increase in the content of nitrites/nitrates (NO(x)) in mouse spinal cord. The rise of spinal NO(x) content by formalin was significantly attenuated by HPE and SJW. The pretreatment with SJW significantly potentiated an antinociceptive effect of morphine (0.3 mg/kg, s.c.), although concentrations of morphine in plasma and brain were not significantly changed by these herbal extracts. In conclusion, the present study has shown that SJW, HPE and GSPE exert significant antinociceptive effects in the formalin test of mice. In addition, opioidergic system seems to be involved in the antinociceptive effect of HPE but not SJW and GSPE. Furthermore, SJW potentiates morphine-induced antinociception possibly by pharmacodynamic interaction.
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Affiliation(s)
- Shinya Uchida
- Department of Pharmacokinetics and Pharmacodynamics and Global COE Program, School of Pharmaceutical Sciences, University of Shizuoka, Suruga-ku, Shizuoka, Japan
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Borsani E, Albertini R, Colleoni M, Sacerdote P, Trovato A, Lonati C, Labanca M, Panerai A, Rezzani R, Rodella L. PPADS, a purinergic antagonist reduces Fos expression at spinal cord level in a mouse model of mononeuropathy. Brain Res 2008; 1199:74-81. [DOI: 10.1016/j.brainres.2007.12.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 12/18/2007] [Accepted: 12/19/2007] [Indexed: 01/12/2023]
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Nishii H, Nomura M, Fujimoto N, Matsumoto T. Thalamic neural activation in the cyclophosphamide-induced visceral pain model in mice. Neurosci Res 2008; 60:219-27. [DOI: 10.1016/j.neures.2007.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 10/15/2007] [Accepted: 11/05/2007] [Indexed: 11/26/2022]
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Tsuda M, Ishii S, Masuda T, Hasegawa S, Nakamura K, Nagata K, Yamashita T, Furue H, Tozaki-Saitoh H, Yoshimura M, Koizumi S, Shimizu T, Inoue K. Reduced pain behaviors and extracellular signal-related protein kinase activation in primary sensory neurons by peripheral tissue injury in mice lacking platelet-activating factor receptor. J Neurochem 2007; 102:1658-1668. [PMID: 17662046 DOI: 10.1111/j.1471-4159.2007.04796.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Peripheral tissue injury causes the release of various mediators from damaged and inflammatory cells, which in turn activates and sensitizes primary sensory neurons and thereby produces persistent pain. The present study investigated the role of platelet-activating factor (PAF), a phospholipid mediator, in pain signaling using mice lacking PAF receptor (pafr-/- mice). Here we show that pafr-/- mice displayed almost normal responses to thermal and mechanical stimuli but exhibit attenuated persistent pain behaviors resulting from tissue injury by locally injecting formalin at the periphery as well as capsaicin pain and visceral inflammatory pain without any alteration in cytoarchitectural or neurochemical properties in dorsal root ganglion (DRG) neurons and a defect in motor function. However, pafr-/- mice showed no alterations in spinal pain behaviors caused by intrathecally administering agonists for N-methyl-d-aspartate (NMDA) and neurokinin(1) receptors. A PAFR agonist evoked an intracellular Ca(2+) response predominantly in capsaicin-sensitive DRG neurons, an effect was not observed in pafr-/- mice. By contrast, the PAFR agonist did not affect C- or Adelta-evoked excitatory post-synaptic currents in substantia gelatinosa neurons in the dorsal horn. Interestingly, mice lacking PAFR showed reduced phosphorylation of extracellular signal-related protein kinase (ERK), an important kinase for the sensitization of primary sensory neurons, in their DRG neurons after formalin injection. Furthermore, U0126, a specific inhibitor of the ERK pathway suppressed the persistent pain by formalin. Thus, PAFR may play an important role in both persistent pain and the sensitization of primary sensory neurons after tissue injury.
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Affiliation(s)
- Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Satoshi Ishii
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Takahiro Masuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Shigeo Hasegawa
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Koji Nakamura
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Kenichiro Nagata
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Tomohiro Yamashita
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Hidemasa Furue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Hidetoshi Tozaki-Saitoh
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Megumu Yoshimura
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Schuichi Koizumi
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Takao Shimizu
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
| | - Kazuhide Inoue
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, JapanPrecursory Research for Embryonic Science and Technology (PRESTO) of Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo, JapanDepartment of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka, JapanDepartment of Pharmacology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo, Yamanashi, Japan
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Wirkner K, Sperlagh B, Illes P. P2X3 receptor involvement in pain states. Mol Neurobiol 2007; 36:165-83. [PMID: 17952660 DOI: 10.1007/s12035-007-0033-y] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Accepted: 03/19/2007] [Indexed: 12/20/2022]
Abstract
The understanding of how pain is processed at each stage in the peripheral and central nervous system is the precondition to develop new therapies for the selective treatment of pain. In the periphery, ATP can be released from various cells as a consequence of tissue injury or visceral distension and may stimulate the local nociceptors. The highly selective distribution of P2X(3) and P2X(2/3) receptors within the nociceptive system has inspired a variety of approaches to elucidate the potential role of ATP as a pain mediator. Depolarization by ATP of neurons in pain-relevant neuronal structures such as trigeminal ganglion, dorsal root ganglion, and spinal cord dorsal horn neurons are well investigated. P2X receptor-mediated afferent activation appears to have been implicated in visceral and neuropathic pain and even in migraine and cancer pain. This article reviews recently published research describing the role that ATP and P2X receptors may play in pain perception, highlighting the importance of the P2X(3) receptor in different states of pain.
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Affiliation(s)
- Kerstin Wirkner
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Haertelstrasse 16-18, 04107, Leipzig, Germany.
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Ikeda H, Tsuda M, Inoue K, Murase K. Long-term potentiation of neuronal excitation by neuron-glia interactions in the rat spinal dorsal horn. Eur J Neurosci 2007; 25:1297-306. [PMID: 17425556 DOI: 10.1111/j.1460-9568.2007.05386.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
By imaging neuronal excitation in rat spinal cord slices with a voltage-sensitive dye, we examined the role of glial cells in the P2X receptor agonist alphabeta-methylene ATP (alphabetameATP)-triggered long-term potentiation (LTP) in the dorsal horn. Bath application of alphabetameATP potentiated neuronal excitation in the superficial dorsal horn. The potentiation was inhibited in the presence of the P2X receptor antagonists TNP-ATP, PPADS and A-317491, and was not induced in slices taken from rats neonatally treated with capsaicin. These results suggest that alphabetameATP acts on P2X receptors, possibly P2X(3) and/or P2X(2/3), in capsaicin-sensitive primary afferent terminals. Furthermore, the potentiation was inhibited by treatment with the glial metabolism inhibitor monofluoroacetic acid. Results obtained with the p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580, tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6, and antibodies to TNF-alpha and IL-6, as well as by double immunolabelling of activated p38 MAPK with markers of astrocytes and microglia, demonstrated that alphabetameATP activated p38 MAPK in astrocytes, and that the presence of proinflammatory cytokines and p38 MAPK activation were necessary for the induction of alphabetameATP-triggered LTP. These findings indicate that glial cells contribute to the alphabetameATP-induced LTP, which might be part of a cellular mechanism for the induction of persistent pain.
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Affiliation(s)
- Hiroshi Ikeda
- Department of Human and Artificial Intelligence Systems, Graduate School of Engineering, and Research and Education Program for Life Science, University of Fukui, 3-9-1 Bunkyo, Fukui 910-8507, Japan.
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Abstract
Many decades have passed since the pain-producing properties of ATP were demonstrated in both animals and humans. However, the more recent discovery of a family of ion channels for which ATP is a ligand and which are expressed by nociceptive neurons, has led to a resurgence of interest into the physiological and pathophysiological actions of ATP. This article considers the extent to which available evidence supports the notion that ATP receptors might be important novel analgesic targets. The hypothesis that ATP is a pain mediator is considered in terms of: the distribution of ATP receptors (specifically the P2X ion channel family); whether ATP release occurs under appropriate conditions; the evidence that ATP is capable of initiating pain in humans and pain-related behaviour in animals; and, lastly, the analgesic effects of pharmacological or molecular block of ATP receptors.
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Affiliation(s)
- Sara G Hamilton
- Neuroscience Research Centre, Guy's King's and Thomas' School of Biomedical Sciences, London, SE1 1UL, United Kingdom.
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Nakagawa T, Wakamatsu K, Zhang N, Maeda S, Minami M, Satoh M, Kaneko S. Intrathecal administration of ATP produces long-lasting allodynia in rats: differential mechanisms in the phase of the induction and maintenance. Neuroscience 2007; 147:445-55. [PMID: 17543465 DOI: 10.1016/j.neuroscience.2007.03.045] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 03/22/2007] [Accepted: 03/23/2007] [Indexed: 01/18/2023]
Abstract
Several lines of evidence suggest that extracellular ATP plays a role in pain signaling through the activation of ionotropic P2X-receptors, especially homomeric P2X3- and heteromeric P2X2/3-receptors on capsaicin-sensitive and -insensitive primary afferent neurons, respectively, at peripheral and spinal sites. We investigated the mechanisms of the induction and maintenance of mechanical allodynia produced by a single intrathecal (i.t.) administration of ATP in rats. We found that i.t. administration of ATP and the P2X-receptor agonist alpha,beta-methylene-ATP produced tactile allodynia which lasted more than 1 week. The i.t. ATP- and alpha,beta-methylene-ATP-produced long-lasting allodynia remained in neonatal capsaicin-treated adult rats. I.t. administration of a P2X3/P2X2/3-receptor selective antagonist completely prevented the induction (co-administration on day 0) and partially attenuated the early phase (day 1 post-ATP administration), but not the late phase (day 7 post-ATP administration) of maintenance of allodynia. The N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 completely prevented the induction phase, but not the early and late phases of maintenance of allodynia. Immunohistochemical and immunoblotting studies for microglial and astrocytic markers revealed that i.t. ATP administration caused spinal microglial activation within 1 day, and astrocytic activation which peaked at 1-3 days after ATP administration. Furthermore, minocycline, a microglial inhibitor, attenuated the induction but not the early and late phases of maintenance, while fluorocitrate, a glial metabolic inhibitor, attenuated the induction and the early phase but not the late phase of maintenance. Taken together, these results suggest that the activation of P2X-receptors, most likely spinal P2X2/3-receptors on capsaicin-insensitive primary afferent neurons, triggers the induction of long-lasting allodynia through NMDA receptors, and the induction and early maintenance phase, but not the late phase, is mediated through the functions of spinal glial cells.
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Affiliation(s)
- T Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
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Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
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Delwing D, Delwing D, Sarkis JJF, Wyse ATS. Proline induces alterations on nucleotide hydrolysis in synaptosomes from cerebral cortex of rats. Brain Res 2007; 1149:210-5. [PMID: 17407768 DOI: 10.1016/j.brainres.2007.02.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 02/19/2007] [Accepted: 02/21/2007] [Indexed: 10/23/2022]
Abstract
In the present study we investigated the in vivo (acute and chronic) and in vitro effects of proline on NTPDase and 5'-nucleotidase activities in synaptosomes obtained from cerebral cortex of rats. For acute administration, 29-day-old rats received one subcutaneous injection of proline (18.2 micromol/g body weight) or an equivalent volume of 0.9% saline solution (control) and were killed 1 h later. For chronic treatment, buffered proline was injected subcutaneously into rats twice a day at 10 h intervals from the 6th to the 28th day of age. Rats were killed 12 h after the last injection. Results showed that acute and chronic proline administration provoked a reduction (25%) of ATP hydrolysis, but did not alter ADP and AMP hydrolysis. We also verified the in vitro effect of proline (3.0 microM-1.0 mM) on nucleotide hydrolysis in synaptosomes from cerebral cortex of rats. In contrast to the in vivo studies, it was not observed any statistically significant alteration on ATP, ADP and AMP hydrolysis. In conclusion, according to our results, it seems reasonable to postulate that proline administration alters the hydrolysis of ATP and probably affects the responses mediated by adenine nucleotides in the central nervous system of proline treated rats.
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Affiliation(s)
- Daniela Delwing
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, Porto Alegre, RS, Brazil
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Ford APDW, Gever JR, Nunn PA, Zhong Y, Cefalu JS, Dillon MP, Cockayne DA. Purinoceptors as therapeutic targets for lower urinary tract dysfunction. Br J Pharmacol 2006; 147 Suppl 2:S132-43. [PMID: 16465177 PMCID: PMC1751490 DOI: 10.1038/sj.bjp.0706637] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Lower urinary tract symptoms (LUTS) are present in many common urological syndromes. However, their current suboptimal management by muscarinic and alpha(1)-adrenoceptor antagonists leaves a significant opportunity for the discovery and development of superior medicines. As potential targets for such therapeutics, purinoceptors have emerged over the last two decades from investigations that have established a prominent role for ATP in the regulation of urinary bladder function under normal and pathophysiological conditions. In particular, evidence suggests that ATP signaling via P2X(1) receptors participates in the efferent control of detrusor smooth muscle excitability, and that this function may be heightened in disease and aging. ATP also appears to be involved in bladder sensation, via activation of P2X(3) and P2X(2/3) receptors on sensory afferent neurons, both within the bladder itself and possibly at central synapses. Such findings are based on results from classical pharmacological and localization studies in non-human and human tissues, knockout mice, and studies using recently identified pharmacological antagonists--some of which possess attributes that offer the potential for optimization into candidate drug molecules. Based on recent advances in this field, it is clearly possible that the development of selective antagonists for these receptors will occur that could lead to therapies offering better relief of sensory and motor symptoms for patients, while minimizing the systemic side effects that limit current medicines.
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Affiliation(s)
- Anthony P D W Ford
- Department of Biochemical Pharmacology, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
- Department of Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Joel R Gever
- Department of Biochemical Pharmacology, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Philip A Nunn
- Department of Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Yu Zhong
- Department of Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Joseph S Cefalu
- Department of Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Michael P Dillon
- Department of Medicinal Chemistry, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
| | - Debra A Cockayne
- Department of Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A
- Neuroscience, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, U.S.A. E-mail:
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Ren Y, Zou X, Fang L, Lin Q. Involvement of peripheral purinoceptors in sympathetic modulation of capsaicin-induced sensitization of primary afferent fibers. J Neurophysiol 2006; 96:2207-16. [PMID: 16885522 DOI: 10.1152/jn.00502.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Purinoceptors are distributed in primary afferent terminals, where transmission of nociceptive information is modulated by these receptors. In the present study, we evaluated whether the activation or blockade of purinoceptors of subtypes P2X and P2Y in the periphery affected the sensitization of primary afferents induced by intradermal injection of capsaicin (CAP) and examined their role in sympathetic modulation of sensitization of primary nociceptive afferents. Afferent activity was recorded from single Adelta- and C-primary afferent fibers in the tibial nerve in anesthetized rats. Peripheral pretreatment with alpha,beta-methylene adenosine 5'-triphosphate (alpha,beta-meATP), a P2X-selective receptor agonist, could potentiate the CAP-induced enhancement of responses of Adelta- and C-primary afferent nociceptive fibers to mechanical stimuli in sympathetically intact rats. After sympathetic denervation, the enhanced responses of both Adelta- and C-fibers after CAP injection were dramatically reduced. However, this reduction could be restored when P2X receptors were activated by alpha,beta-meATP. A blockade of P2X receptors by pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid could significantly reduce the CAP-induced sensitization of Adelta- and C-fibers. Pretreatment with uridine 5'-triphosphate, a P2Y-selective receptor agonist, did not significantly affect or restore the CAP-induced sensitization of Adelta- and C-fibers under sympathetically intact or sympathectomized conditions. Our study supports the view that ATP plays a role in modulation of primary afferent nociceptor sensitivity mainly by P2X receptors. Combined with our previous study, our data also provide further evidence that the sensitization of primary afferent nociceptors is subject to sympathetic modulation by activation of P2X as well as alpha(1)-adrenergic receptors.
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Affiliation(s)
- Yong Ren
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-1069, USA
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Makowska A, Panfil C, Ellrich J. ATP induces sustained facilitation of craniofacial nociception through P2X receptors on neck muscle nociceptors in mice. Cephalalgia 2006; 26:697-706. [PMID: 16686909 DOI: 10.1111/j.1468-2982.2006.01095.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Noxious input from neck muscles probably plays a key role in tension-type headache pathophysiology. ATP selectively excites group III and IV muscle afferents in vitro. Accordingly, ATP infusion into trapezius muscle induces strong pain and local tenderness in healthy man. The present study addresses the impact of ATP on neck muscle nociception in anaesthetized mice. Craniofacial nociceptive processing was tested by the jaw-opening reflex via noxious electrical tongue stimulation. Within 2 h after injection of 100 nmol/l or 1 micromol/l ATP into semispinal neck muscles, reflex integrals significantly increased by 114% or 328%, respectively. Preceding intramuscular administration of the P2X receptor antagonist PPADS (3-100 nmol/l) suppressed the ATP effect. Subsequent application of PPADS (100 nmol/l) caused a total recovery of facilitated reflex to baseline values. ATP induces sustained facilitation of craniofacial nociception by prolonged excitation of P2X receptors in neck muscles.
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Affiliation(s)
- A Makowska
- Department of Neurosurgery, Experimental Neurosurgery Section, Medical Faculty, RWTH Aachen University, Aachen, Germany
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Fukui M, Nakagawa T, Minami M, Satoh M, Kaneko S. Inhibitory role of supraspinal P2X3/P2X2/3 subtypes on nociception in rats. Mol Pain 2006; 2:19. [PMID: 16753051 PMCID: PMC1557483 DOI: 10.1186/1744-8069-2-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Accepted: 06/05/2006] [Indexed: 11/20/2022] Open
Abstract
Extracellular ATP is known to mediate synaptic transmission as a neurotransmitter or a neuromodulator via ionotropic P2X and metabotropic P2Y receptors. Several lines of evidence have suggested that ATP facilitates pain transmission at peripheral and spinal sites via the P2X receptors, in which the P2X3 subtype is considered as an important candidate for the effect. Conversely, we previously found that the activation of supraspinal P2X receptors evoked antinociception. However, the subtypes responsible for the antinociception via supraspinal P2X receptors remain unclear. In the present study, we showed that intracerebroventricular (i.c.v.) pretreatment with A-317491 (1 nmol), the novel non-nucleotide antagonist selective for P2X3 and P2X2/3 receptors, attenuated the antinociceptive effect produced by i.c.v. administered α,β-methylene-ATP (10 nmol), the P2X receptor agonist, in rats. Similarly, the abolishment of the P2X3 receptor mRNA in the brainstem by repeated i.c.v. pretreatments with antisense oligodeoxynucleotide for P2X3 gene once a day for 5 consecutive days diminished the antinociceptive effect of α,β-methylene-ATP. Furthermore, i.c.v. administration of A-317491 (1 and 10 nmol) significantly enhanced the inflammatory nociceptive behaviors induced by the intraplantar injection of formalin and intraperitoneal injection of acetic acid. Taken together, these results suggest that supraspinal P2X3/P2X2/3 receptors play an inhibitory role in pain transmission.
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Affiliation(s)
- Masato Fukui
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Takayuki Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Masabumi Minami
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | | | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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Gever JR, Cockayne DA, Dillon MP, Burnstock G, Ford APDW. Pharmacology of P2X channels. Pflugers Arch 2006; 452:513-37. [PMID: 16649055 DOI: 10.1007/s00424-006-0070-9] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 03/08/2006] [Indexed: 02/07/2023]
Abstract
Significant progress in understanding the pharmacological characteristics and physiological importance of homomeric and heteromeric P2X channels has been achieved in recent years. P2X channels, gated by ATP and most likely trimerically assembled from seven known P2X subunits, are present in a broad distribution of tissues and are thought to play an important role in a variety of physiological functions, including peripheral and central neuronal transmission, smooth muscle contraction, and inflammation. The known homomeric and heteromeric P2X channels can be distinguished from each other on the basis of pharmacological differences when expressed recombinantly in cell lines, but whether this pharmacological classification holds true in native cells and in vivo is less well-established. Nevertheless, several potent and selective P2X antagonists have been discovered in recent years and shown to be efficacious in various animal models including those for visceral organ function, chronic inflammatory and neuropathic pain, and inflammation. The recent advancement of drug candidates targeting P2X channels into human trials, confirms the medicinal exploitability of this novel target family and provides hope that safe and effective medicines for the treatment of disorders involving P2X channels may be identified in the near future.
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Affiliation(s)
- Joel R Gever
- Department of Biochemical Pharmacology, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, USA.
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Lindfors PH, Võikar V, Rossi J, Airaksinen MS. Deficient nonpeptidergic epidermis innervation and reduced inflammatory pain in glial cell line-derived neurotrophic factor family receptor alpha2 knock-out mice. J Neurosci 2006; 26:1953-60. [PMID: 16481427 PMCID: PMC6674922 DOI: 10.1523/jneurosci.4065-05.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Most unmyelinated nociceptive neurons that mediate pain and temperature sensation from the skin bind isolectin B4 (IB4)-lectin and express Ret, the common signaling component of glial cell line-derived neurotrophic factor (GDNF) family. One of these factors, neurturin, is expressed in the epidermis, whereas its GDNF family receptor alpha2 (GFRalpha2) is expressed in the majority of unmyelinated Ret-positive sensory neurons. However, the physiological roles of endogenous neurturin signaling in primary sensory neurons are poorly understood. Here, we show that the vast majority (approximately 85%) of IB4 binding and P2X3 purinoreceptor-positive neurons, but virtually none of the calcitonin gene-related peptide (CGRP) or vanilloid receptor transient receptor potential vanilloid 1-positive neurons in mouse dorsal root ganglion (DRG) express GFRalpha2. In GFRalpha2 knock-out (KO) mice, the IB4-binding and P2X3-positive DRG neurons were present but reduced in size, consistent with normal number but reduced caliber of unmyelinated axons in a cutaneous nerve. Strikingly, nonpeptidergic (CGRP-negative) free nerve endings in footpad epidermis were >70% fewer in GFRalpha2-KO mice than in their wild-type littermates. In contrast, the density of CGRP-positive epidermal innervation remained unaffected. In the formalin test, the KO mice showed a normal acute response but a markedly attenuated persistent phase, indicating a deficit in inflammatory pain response. Behavioral responses of GFRalpha2-KO mice to innocuous warm and noxious heat were not blunted; the mice were actually markedly hypersensitive to noxious cold in tail immersion test. Overall, our results indicate a critical role for endogenous GFRalpha2 signaling in maintaining the size and terminal innervation of the nonpeptidergic class of cutaneous nociceptors in vivo.
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Nakatsuka T, Gu JG. P2X purinoceptors and sensory transmission. Pflugers Arch 2006; 452:598-607. [PMID: 16547751 DOI: 10.1007/s00424-006-0057-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Accepted: 02/13/2006] [Indexed: 01/26/2023]
Abstract
The involvement of P2X purinoreceptors (P2X receptors) in somatosensory transmission is herein reviewed with a focus on those receptors that are expressed on sensory neurons to elucidate their roles in the initiation of sensory excitation from primary afferent neurons, in modulating synaptic transmission at the first sensory synapses formed between primary afferent central terminals and dorsal horn neurons, in directly mediating sensory synaptic transmission to the spinal cord dorsal horn, and in modulating synaptic transmission among spinal cord dorsal horn neurons. Research on P2X receptors has indicated that these receptors play a significant role in both physiological and pathological pain states. As a result, P2X receptors may serve as therapeutic targets for the treatment of pathological pain conditions associated with nerve injury, tissue inflammation, cancer, and other diseases.
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Affiliation(s)
- Terumasa Nakatsuka
- Department of Physiology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
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Parvizpur A, Ahmadiani A, Kamalinejad M. Probable role of spinal purinoceptors in the analgesic effect of Trigonella foenum (TFG) leaves extract. JOURNAL OF ETHNOPHARMACOLOGY 2006; 104:108-12. [PMID: 16298092 DOI: 10.1016/j.jep.2005.08.057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Revised: 08/05/2005] [Accepted: 08/26/2005] [Indexed: 05/05/2023]
Abstract
In our previous work, we demonstrated that Trigonella foenum (TFG) leaves extract can exert analgesic effects in both formalin (F.T.) and tail flick (T.F.) tests. Spinal serotonergic system, but not endogenous opioid system, was involved in TFG induced analgesia (in the second phase of formalin test). Some reports concern the similarity between NSAIDs and TFG extract in many pharmacological effects or the interaction between NSAIDs and purinergic system; so the present study was designed to investigate the relationship between TFG extract and purinergic system or the inhibition of cyclo-oxygenase (COX). We examined the effect of TFG extract on: (1) the response of rabbit platelets to ADP induced aggregation, (2) the contraction of mouse vas deferens induced by alpha,beta-Me-ATP (a P(2) receptor agonist; this receptor mediates the rapid phase of ADP- and ATP-evoked influx of Ca(2+) through a non-specific cation channel in platelets), (3) alpha,beta-Me-ATP induced hyperalgesia in tail flick test in male rats and (4) the specific inhibition of COX-1 and COX-2. Our results showed that TFG extract (0.5, 1, 1.5, 3 mg/ml) inhibited ADP (10(-5) mol) induced platelet aggregation (IC(50)=1.28 mg/ml). alpha,beta-Me-ATP (30 microM) induced isometric contraction in vas deferens while suramin (a P(2) receptor antagonist, 50, 150, 300 microM) or TFG extract (0.5, 1, 2, 3 mg/ml) inhibited this effect significantly (IC(50) were 91.07 microM and 1.57 mg/ml, respectively). Moreover, alpha,beta-Me-ATP (3 microg/rat, i.t.) induced hyperalgesia in tail flick test, but it was prevented by co-injection of alpha,beta-Me-ATP with suramin (120 microg/rat, i.t.) or TFG extract (1mg/rat, i.t.). Effective concentrations of TFG extract in the above mentioned experiments did not inhibit COX enzymes in EIA tests. In conclusion, these results indicate that the blocking of spinal purinoceptors may contribute in the analgesic effect of TFG leaves extract.
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Affiliation(s)
- Aliresa Parvizpur
- Neuroscience Research Center, Department of Pharmacology, School of Medicine, Shaheed Beheshti University of Medical Sciences, P.O. Box 19835-355, Tehran, Iran
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