1
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Comeo E, Goulding J, Lin CY, Groenen M, Woolard J, Kindon ND, Harwood CR, Platt S, Briddon SJ, Kilpatrick LE, Scammells PJ, Hill SJ, Kellam B. Ligand-Directed Labeling of the Adenosine A 1 Receptor in Living Cells. J Med Chem 2024. [PMID: 38994645 DOI: 10.1021/acs.jmedchem.4c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The study of protein function and dynamics in their native cellular environment is essential for progressing fundamental science. To overcome the requirement of genetic modification of the protein or the limitations of dissociable fluorescent ligands, ligand-directed (LD) chemistry has most recently emerged as a complementary, bioorthogonal approach for labeling native proteins. Here, we describe the rational design, development, and application of the first ligand-directed chemistry approach for labeling the A1AR in living cells. We pharmacologically demonstrate covalent labeling of A1AR expressed in living cells while the orthosteric binding site remains available. The probes were imaged using confocal microscopy and fluorescence correlation spectroscopy to study A1AR localization and dynamics in living cells. Additionally, the probes allowed visualization of the specific localization of A1ARs endogenously expressed in dorsal root ganglion (DRG) neurons. LD probes developed here hold promise for illuminating ligand-binding, receptor signaling, and trafficking of the A1AR in more physiologically relevant environments.
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Affiliation(s)
- Eleonora Comeo
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Joëlle Goulding
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Chia-Yang Lin
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Marleen Groenen
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Nicholas D Kindon
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Clare R Harwood
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Simon Platt
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Laura E Kilpatrick
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Barrie Kellam
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
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2
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Gao ZG, Haddad M, Jacobson KA. A 2B adenosine receptor signaling and regulation. Purinergic Signal 2024:10.1007/s11302-024-10025-y. [PMID: 38833181 DOI: 10.1007/s11302-024-10025-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 05/20/2024] [Indexed: 06/06/2024] Open
Abstract
The A2B adenosine receptor (A2BR) is one of the four adenosine-activated G protein-coupled receptors. In addition to adenosine, protein kinase C (PKC) was recently found to activate the A2BR. The A2BR is coupled to both Gs and Gi, as well as Gq proteins in some cell types. Many primary cells and cell lines, such as bladder and breast cancer, bronchial smooth muscle, skeletal muscle, and fat cells, express the A2BR endogenously at high levels, suggesting its potentially important role in asthma, cancer, diabetes, and other conditions. The A2BR has been characterized as both pro- and anti-inflammatory, inducing cell type-dependent secretion of IL-6, IL-8, and IL-10. Theophylline and enprofylline have long been used for asthma treatment, although it is still not entirely clear if their A2BR antagonism contributes to their therapeutic effects or side effects. The A2BR is required in ischemic cardiac preconditioning by adenosine. Both A2BR and protein kinase C (PKC) contribute to cardioprotection, and both modes of A2BR signaling can be blocked by A2BR antagonists. Inhibitors of PKC and A2BR are in clinical cancer trials. Sulforaphane and other isothiocyanates from cruciferous vegetables such as broccoli and cauliflower have been reported to inhibit A2BR signaling via reaction with an intracellular A2BR cysteine residue (C210). A full, A2BR-selective agonist, critical to elucidate many controversial roles of the A2BR, is still not available, although agonist-bound A2BR structures have recently been reported.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
| | - Mansour Haddad
- Faculty of Pharmacy, Yarmouk University, Irbid, 21163, Jordan
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
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3
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Haddad M, Cherchi F, Alsalem M, Al-saraireh YM, Madae’en S. Adenosine Receptors as Potential Therapeutic Analgesic Targets. Int J Mol Sci 2023; 24:13160. [PMID: 37685963 PMCID: PMC10487796 DOI: 10.3390/ijms241713160] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 08/18/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
Pain represents an international burden and a major socio-economic public health problem. New findings, detailed in this review, suggest that adenosine plays a significant role in neuropathic and inflammatory pain, by acting on its metabotropic adenosine receptors (A1AR, A2AAR, A2BAR, A3AR). Adenosine receptor ligands have a practical translational potential based on the favorable efficacy and safety profiles that emerged from clinical research on various agonists and antagonists for different pathologies. The present review collects the latest studies on selected adenosine receptor ligands in different pain models. Here, we also covered the many hypothesized pathways and the role of newly synthesized allosteric adenosine receptor modulators. This review aims to present a summary of recent research on adenosine receptors as prospective therapeutic targets for a range of pain-related disorders.
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Affiliation(s)
- Mansour Haddad
- Faculty of Pharmacy, Yarmouk University, Irbid 21163, Jordan
| | - Federica Cherchi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy;
| | - Mohammad Alsalem
- School of Medicine, The University of Jordan, Amman 11942, Jordan;
| | - Yousef M. Al-saraireh
- Department of Pharmacology, Faculty of Medicine, Mutah University, P.O. Box 7, Al-Karak 61710, Jordan;
| | - Saba Madae’en
- Department of Clinical Pharmacy and Pharmacy Practice, Faculty of Pharmaceutical Sciences, The Hashemite University, Zarqa 13133, Jordan;
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4
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Zhou M, Wu J, Chang H, Fang Y, Zhang D, Guo Y. Adenosine signaling mediate pain transmission in the central nervous system. Purinergic Signal 2023; 19:245-254. [PMID: 35000074 PMCID: PMC9984632 DOI: 10.1007/s11302-021-09826-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/29/2021] [Indexed: 12/14/2022] Open
Abstract
Pain is a common clinical symptom that seriously affects the quality of life in a variety of patient populations. In recent years, research on the role of adenosine signaling in pain modulation has made great progress. Adenosine is a purine nucleoside and a neuromodulator, and regulates multiple physiological and pathophysiological functions through the activation of four G protein-coupled receptors, which are classified as A1, A2A, A2B, and A3 adenosine receptors (ARs). Adenosine and its receptors that are widespread in the central nervous system (CNS) play an important role in the processing of nociceptive sensory signals in different pain models. A1Rs have the highest affinity to adenosine, and the role in analgesia has been well investigated. The roles of A2ARs and A2BRs in the modulation of pain are controversial because they have both analgesic and pronociceptive effects. The analgesic effects of A3Rs are primarily manifested in neuropathic pain. In this article, we have reviewed the recent studies on ARs in the modulation of neuropathic pain, inflammatory pain, postoperative pain, and visceral pain in the CNS. Furthermore, we have outlined the pathways through which ARs contribute to pain regulation, thereby shedding light on how this mechanism can be targeted to provide effective pain relief.
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Affiliation(s)
- Mengmeng Zhou
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Jinrong Wu
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Hongen Chang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China
| | - Yuxin Fang
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
| | - Di Zhang
- College of Pharmaceutical Engineering of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
| | - Yi Guo
- Research Center of Experimental Acupuncture Science, College of Acumox and Tuina, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China. .,College of Chinese Medical, Tianjin University of Traditional Chinese Medicine, Tianjin, 301617, People's Republic of China.
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5
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Hao JW, Qiao WL, Li Q, Wei S, Li XM, Liu TT, Qiu CY, Hu WP. A1 Adenosine Receptor Activation Inhibits P2X3 Receptor-Mediated ATP Currents in Rat Dorsal Root Ganglion Neurons. Mol Neurobiol 2022; 59:7025-7035. [PMID: 36074232 DOI: 10.1007/s12035-022-03019-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 08/26/2022] [Indexed: 10/14/2022]
Abstract
Purinergic signaling is involved in multiple pain processes. P2X3 receptor is a key target in pain therapeutics, while A1 adenosine receptor signaling plays a role in analgesia. However, it remains unclear whether there is a link between them in pain. The present results showed that the A1 adenosine receptor agonist N6-cyclopentyladenosine (CPA) concentration dependently suppressed P2X3 receptor-mediated and α,β-methylene-ATP (α,β-meATP)-evoked inward currents in rat dorsal root ganglion (DRG) neurons. CPA significantly decreased the maximal current response to α,β-meATP, as shown a downward shift of the concentration-response curve for α,β-meATP. CPA suppressed ATP currents in a voltage-independent manner. Inhibition of ATP currents by CPA was completely prevented by the A1 adenosine receptor antagonist KW-3902, and disappeared after the intracellular dialysis of either the Gi/o protein inhibitor pertussis toxin, the adenylate cyclase activator forskolin, or the cAMP analog 8-Br-cAMP. Moreover, CPA suppressed the membrane potential depolarization and action potential bursts, which were induced by α,β-meATP in DRG neurons. Finally, CPA relieved α,β-meATP-induced nociceptive behaviors in rats by activating peripheral A1 adenosine receptors. These results indicated that CPA inhibited the activity of P2X3 receptors in rat primary sensory neurons by activating A1 adenosine receptors and its downstream cAMP signaling pathway, revealing a novel peripheral mechanism underlying its analgesic effect.
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Affiliation(s)
- Jia-Wei Hao
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China.,School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Wen-Long Qiao
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China.,School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Qing Li
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China.,School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Shuang Wei
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China.,School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Xue-Mei Li
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Ting-Ting Liu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Chun-Yu Qiu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China
| | - Wang-Ping Hu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, People's Republic of China. .,Hubei College of Chinese Medicine, 87 Xueyuan Road, Jingzhou, 434020, Hubei, People's Republic of China.
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6
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Tozaki-Saitoh H, Takeda H, Inoue K. The Role of Microglial Purinergic Receptors in Pain Signaling. Molecules 2022; 27:molecules27061919. [PMID: 35335282 PMCID: PMC8949888 DOI: 10.3390/molecules27061919] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/10/2022] [Accepted: 03/14/2022] [Indexed: 12/25/2022] Open
Abstract
Pain is an essential modality of sensation in the body. Purinergic signaling plays an important role in nociceptive pain transmission, under both physiological and pathophysiological conditions, and is important for communication between both neuronal and non-neuronal cells. Microglia and astrocytes express a variety of purinergic effectors, and a variety of receptors play critical roles in the pathogenesis of neuropathic pain. In this review, we discuss our current knowledge of purinergic signaling and of the compounds that modulate purinergic transmission, with the aim of highlighting the importance of purinergic pathways as targets for the treatment of persistent pain.
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Affiliation(s)
- Hidetoshi Tozaki-Saitoh
- Department of Pharmacology, School of Pharmacy at Fukuoka, International University of Health and Welfare, 137-1 Enokizu, Okawa 831-8501, Japan;
- Correspondence: ; Tel.: +81-944-32-6137
| | - Hiroshi Takeda
- Department of Pharmacology, School of Pharmacy at Fukuoka, International University of Health and Welfare, 137-1 Enokizu, Okawa 831-8501, Japan;
| | - Kazuhide Inoue
- Institute for Advanced Study, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan;
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7
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Jung SM, Peyton L, Essa H, Choi DS. Adenosine receptors: Emerging non-opioids targets for pain medications. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2022; 11:100087. [PMID: 35372716 PMCID: PMC8971635 DOI: 10.1016/j.ynpai.2022.100087] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022]
Abstract
Physical and emotional pain deteriorates the quality of well-being. Also, numerous non-invasive and invasive treatments for diagnosed diseases such as cancer medications and surgical procedures cause various types of pain. Despite the multidisciplinary approaches available to manage pain, the unmet needs for medication with minimal side effects are substantial. Especially with the surge of opioid crisis during the last decades, non-opioid analgesics may reduce life-threatening overdosing and addictive liability. Although many clinical trials supported the potential potency of cannabis and cannabidiol (CBD) in pain management or treatment, the long-term benefits of cannabis or CBD are still not evident. At the same time, growing evidence shows the risk of overusing cannabis and CBD. Therefore, it is urgent to develop novel analgesic medications that minimize side effects. All four well-identified adenosine receptors, A1, A2A, A2B, and A3, are implicated in pain. Recently, a report demonstrated that an adenosine A1R-specific positive allosteric modulator (PAM) is a potent analgesic without noticeable side effects. Also, several A3R agonists are being considered as promising analgesic agent. However, the importance of adenosine in pain is relatively underestimated. To help readers understand, first, we will summarize the historical perspective of the adenosine system in preclinical and clinical studies. Then, we will discuss possible interactions of adenosine and opioids or the cannabis system focusing on pain. Overall, this review will provide the potential role of adenosine and adenosine receptors in pain treatment.
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Affiliation(s)
- Soo-Min Jung
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Lee Peyton
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Hesham Essa
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States.,Neuroscience Program, Mayo Clinic College of Medicine and Science, Rochester, MN, United States.,Department of Psychiatry and Psychology, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
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8
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Wei S, Hao JW, Qiao WL, Li Q, Liu TT, Qiu CY, Hu WP. Suppression of ASIC activity by the activation of A1 adenosine receptors in rat primary sensory neurons. Neuropharmacology 2021; 205:108924. [PMID: 34919904 DOI: 10.1016/j.neuropharm.2021.108924] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/21/2021] [Accepted: 12/10/2021] [Indexed: 11/25/2022]
Abstract
Peripheral A1 adenosine receptor signaling has been shown to have analgesic effects in a variety of pain conditions. However, it is not yet fully elucidated for the precise molecular mechanisms. Acid sensing ion channels (ASICs) are expressed predominantly in nociceptive sensory neurons responding to protons. Given that both A1 adenosine receptors and ASICs are present in dorsal root ganglia (DRG) neurons, we therefore investigated whether there was a cross-talk between the two types of receptors. Herein, electrophysiological recordings showed that the A1 adenosine receptor agonist N6-cyclopentyladenosine (CPA) suppressed acid-induced currents and action potentials, which were mediated by ASICs, in rat DRG neurons. CPA inhibited the maximum response to protons, as shown a downward shift of concentration-response curve for protons. The CPA-induced suppression of ASIC currents was blocked by the A1 adenosine receptor antagonist KW-3902 and also prevented by intracellular application of the Gi/o-protein inhibitor pertussis toxin, the adenylate cyclase activator forskolin, and the cAMP analog 8-Br-cAMP. Finally, intraplantar pretreatment of CPA dose-dependently relieved acid-induced nociceptive responses in rats through peripheral A1 adenosine receptors. These results suggested that CPA suppressed ASICs via A1 adenosine receptors and intracellular Gi/o-proteins and cAMP signaling cascades in rat DRG neurons, which was a novel potential mechanism underlying analgesia of peripheral A1 adenosine receptors.
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Affiliation(s)
- Shuang Wei
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Jia-Wei Hao
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Wen-Long Qiao
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Qing Li
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Ting-Ting Liu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Chun-Yu Qiu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China
| | - Wang-Ping Hu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, 88 Xianning Road, Xianning, 437100, Hubei, PR China; Hubei College of Chinese Medicine, 87 Xueyuan Road, Jingzhou, 434020, Hubei, PR China.
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9
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Positive allosteric mechanisms of adenosine A 1 receptor-mediated analgesia. Nature 2021; 597:571-576. [PMID: 34497422 PMCID: PMC8711093 DOI: 10.1038/s41586-021-03897-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 08/11/2021] [Indexed: 02/08/2023]
Abstract
The adenosine A1 receptor (A1R) is a promising therapeutic target for non-opioid analgesic agents to treat neuropathic pain1,2. However, development of analgesic orthosteric A1R agonists has failed because of a lack of sufficient on-target selectivity as well as off-tissue adverse effects3. Here we show that [2-amino-4-(3,5-bis(trifluoromethyl)phenyl)thiophen-3-yl)(4-chlorophenyl)methanone] (MIPS521), a positive allosteric modulator of the A1R, exhibits analgesic efficacy in rats in vivo through modulation of the increased levels of endogenous adenosine that occur in the spinal cord of rats with neuropathic pain. We also report the structure of the A1R co-bound to adenosine, MIPS521 and a Gi2 heterotrimer, revealing an extrahelical lipid-detergent-facing allosteric binding pocket that involves transmembrane helixes 1, 6 and 7. Molecular dynamics simulations and ligand kinetic binding experiments support a mechanism whereby MIPS521 stabilizes the adenosine-receptor-G protein complex. This study provides proof of concept for structure-based allosteric drug design of non-opioid analgesic agents that are specific to disease contexts.
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10
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Functional and Anatomical Characterization of Corticotropin-Releasing Factor Receptor Subtypes of the Rat Spinal Cord Involved in Somatic Pain Relief. Mol Neurobiol 2021; 58:5459-5472. [PMID: 34331656 PMCID: PMC8599353 DOI: 10.1007/s12035-021-02481-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2021] [Indexed: 12/17/2022]
Abstract
Corticotropin-releasing factor (CRF) orchestrates our body’s response to stressful stimuli. Pain is often stressful and counterbalanced by activation of CRF receptors along the nociceptive pathway, although the involvement of the CRF receptor subtypes 1 and/or 2 (CRF-R1 and CRF-R2, respectively) in CRF-induced analgesia remains controversial. Thus, the aim of the present study was to examine CRF-R1 and CRF-R2 expression within the spinal cord of rats with Freund’s complete adjuvant-induced unilateral inflammation of the hind paw using reverse transcriptase polymerase chain reaction, Western blot, radioligand binding, and immunofluorescence confocal analysis. Moreover, the antinociceptive effects of intrathecal (i.t.) CRF were measured by paw pressure algesiometer and their possible antagonism by selective antagonists for CRF-R1 and/or CRF-R2 as well as for opioid receptors. Our results demonstrated a preference for the expression of CRF-R2 over CRF-R1 mRNA, protein, binding sites and immunoreactivity in the dorsal horn of the rat spinal cord. Consistently, CRF as well as CRF-R2 agonists elicited potent dose-dependent antinociceptive effects which were antagonized by the i.t. CRF-R2 selective antagonist K41498, but not by the CRF-R1 selective antagonist NBI35965. In addition, i.t. applied opioid antagonist naloxone dose-dependently abolished the i.t. CRF- as well as CRF-R2 agonist-elicited inhibition of somatic pain. Importantly, double immunofluorescence confocal microscopy of the spinal dorsal horn showed CRF-R2 on enkephalin (ENK)-containing inhibitory interneurons in close opposition of incoming mu-opioid receptor-immunoreactive nociceptive neurons. CRF-R2 was, however, not seen on pre- or on postsynaptic sensory neurons of the spinal cord. Taken together, these findings suggest that i.t. CRF or CRF-R2 agonists inhibit somatic inflammatory pain predominantly through CRF-R2 receptors located on spinal enkephalinergic inhibitory interneurons which finally results in endogenous opioid-mediated pain inhibition.
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11
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Metzner K, Gross T, Balzulat A, Wack G, Lu R, Schmidtko A. Lack of efficacy of a partial adenosine A1 receptor agonist in neuropathic pain models in mice. Purinergic Signal 2021; 17:503-514. [PMID: 34313915 PMCID: PMC8410902 DOI: 10.1007/s11302-021-09806-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 06/28/2021] [Indexed: 12/25/2022] Open
Abstract
Previous studies suggest that adenosine A1 receptors (A1R) modulate the processing of pain. The aim of this study was to characterize the distribution of A1R in nociceptive tissues and to evaluate whether targeting A1R with the partial agonist capadenoson may reduce neuropathic pain in mice. The cellular distribution of A1R in dorsal root ganglia (DRG) and the spinal cord was analyzed using fluorescent in situ hybridization. In behavioral experiments, neuropathic pain was induced by spared nerve injury or intraperitoneal injection of paclitaxel, and tactile hypersensitivities were determined using a dynamic plantar aesthesiometer. Whole-cell patch-clamp recordings were performed to assess electrophysiological properties of dissociated DRG neurons. We found A1R to be expressed in populations of DRG neurons and dorsal horn neurons involved in the processing of pain. However, administration of capadenoson at established in vivo doses (0.03–1.0 mg/kg) did not alter mechanical hypersensitivity in the spared nerve injury and paclitaxel models of neuropathic pain, whereas the standard analgesic pregabalin significantly inhibited the pain behavior. Moreover, capadenoson failed to affect potassium currents in DRG neurons, in contrast to a full A1R agonist. Despite expression of A1R in nociceptive neurons, our data do not support the hypothesis that pharmacological intervention with partial A1R agonists might be a valuable approach for the treatment of neuropathic pain.
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Affiliation(s)
- Katharina Metzner
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Annika Balzulat
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Gesine Wack
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Ruirui Lu
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
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Needling Interventions for Sciatica: Choosing Methods Based on Neuropathic Pain Mechanisms-A Scoping Review. J Clin Med 2021; 10:jcm10102189. [PMID: 34069357 PMCID: PMC8158699 DOI: 10.3390/jcm10102189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 02/06/2023] Open
Abstract
Sciatica is a condition often accompanied by neuropathic pain (NP). Acupuncture and dry needling are common treatments for pain, and the current literature supports acupuncture as an effective treatment for sciatica. However, it is unknown if the mechanisms of NP are considered in the delivery of needling interventions for sciatica. Our objective was to assess the efficacy and the effectiveness of needling therapies, to identify common needling practices and to investigate if NP mechanisms are considered in the treatment of sciatica. A scoping review of the literature on needling interventions for sciatica and a review of the literature on mechanisms related to NP and needling interventions were performed. Electronic literature searches were conducted on PubMed, MEDLINE, CINAHL and Cochrane Database of Systematic Reviews from inception to August, 2020 to identify relevant papers. Reference lists of included papers were also manually screened and a related-articles search through PubMed was performed on all included articles. Mapping of the results included description of included studies, summary of results, and identification of gaps in the existing literature. Ten articles were included. All studies used acupuncture for the treatment of sciatica, no studies on dry needling were identified. Current evidence supports the efficacy and effectiveness of acupuncture for sciatica, however, no studies considered underlying NP mechanisms in the acupuncture approach for sciatica and the rationale for using acupuncture was inconsistent among trials. This review reveals that neuropathic pain mechanisms are not routinely considered in needling approaches for patients with sciatica. Studies showed acupuncture to be an effective treatment for sciatic pain, however, further research is warranted to explore if needling interventions for sciatica and NP would be more effective if NP mechanisms are considered.
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The role of peripheral adenosine receptors in glutamate-induced pain nociceptive behavior. Purinergic Signal 2021; 17:303-312. [PMID: 33860899 DOI: 10.1007/s11302-021-09781-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 03/15/2021] [Indexed: 12/13/2022] Open
Abstract
The role of peripheral adenosine receptors in pain is a controversial issue and seems to be quite different from the roles of spinal and central adenosine receptors. The present study is aimed at clarifying the role of these receptors in peripheral nociception. To clarify this, studies were done on Swiss mice with adenosine receptor agonists and antagonists. Nociceptive behavior was induced by subcutaneous injection of glutamate (10 μmol) into the ventral surface of the hind paw of mice. Statistical analyses were performed by one-way ANOVA followed by the Student-Newman-Keuls post hoc test. Results showed that intraplantar (i.pl.) administration of N6-cyclohexyl-adenosine (CHA), an adenosine A1 receptor agonist, at 1 or 10 μg/paw significantly reduced glutamate-induced nociception (p<0.01 and p<0.001 vs. vehicle, respectively, n=8-10). In contrast, i.pl. injection of hydrochloride hydrate (CGS21680, an adenosine A2A receptor agonist) (1 μg/paw) induced a significant increase in glutamate-induced nociception compared to the vehicle (p<0.05, n=8), while 4-(-2-[7-amino-2-{2-furyl}{1,2,4}triazolo{2,3-a} {1,3,5}triazin-5-yl-amino]ethyl)phenol (ZM241385, an adenosine A2A receptor antagonist) (20 μg/paw) caused a significant reduction (p<0.05, n=7-8). There were no significant effects on i.pl. administration of four additional adenosine receptor drugs-8-cyclopentyl-1,3-dipropylxanthine (DPCPX, an A1 antagonist, 1-10 μg/paw), N(6)-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA, an A2B agonist, 1-100 μg/paw), alloxazine (an A2B antagonist, 0.1-3 μg/paw), and 2-hexyn-1-yl-N(6)-methyladenosine (HEMADO) (an A3 agonist, 1-100 μg/paw) (p>0.05 vs. vehicle for all tests). We also found that prior administration of DPCPX (3 μg/paw) significantly blocked the anti-nociceptive effect of CHA (1 μg/paw) (p<0.05, n=7-9). Similarly, ZM241385 (20 μg/paw) administered prior to CGS21680 (1 μg/paw) significantly blocked CGS21680-induced exacerbation of nociception (p<0.05, n=8). Finally, inosine (10 and 100 μg/paw), a novel endogenous adenosine A1 receptor agonist recently reported by our research group, was also able to reduce glutamate-induced nociception (p<0.001 vs. vehicle, n=7-8). Interestingly, as an A1 adenosine receptor agonist, the inosine effect was significantly blocked by the A1 antagonist DPCPX (3 μg/paw) (p<0.05, n=7-9) but not by the A2A antagonist ZM241385 (10 μg/paw, p>0.05). In summary, these results demonstrate for the first time that i.pl administration of inosine induces an anti-nociceptive effect, similar to that elicited by CHA and possibly mediated by peripheral adenosine A1 receptor activation. Moreover, our results suggest that peripheral adenosine A2A receptor activation presents a pro-nociceptive effect, exacerbating glutamate-induced nociception independent of inosine-induced anti-nociceptive effects.
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Selvi I, Argun G, Sonmez C, Bozkurt OF, Basar H. Raised Adenosine and Adenosine Deaminase in Bladder Cancer Require Less Postoperative Analgesia Compared with Benign Prostatic Hyperplasia After Transurethral Resection. Indian J Surg 2021. [DOI: 10.1007/s12262-020-02272-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Targeting Adenosine Receptors: A Potential Pharmacological Avenue for Acute and Chronic Pain. Int J Mol Sci 2020; 21:ijms21228710. [PMID: 33218074 PMCID: PMC7698931 DOI: 10.3390/ijms21228710] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/17/2020] [Indexed: 12/14/2022] Open
Abstract
Adenosine is a purine nucleoside, responsible for the regulation of multiple physiological and pathological cellular and tissue functions by activation of four G protein-coupled receptors (GPCR), namely A1, A2A, A2B, and A3 adenosine receptors (ARs). In recent years, extensive progress has been made to elucidate the role of adenosine in pain regulation. Most of the antinociceptive effects of adenosine are dependent upon A1AR activation located at peripheral, spinal, and supraspinal sites. The role of A2AAR and A2BAR is more controversial since their activation has both pro- and anti-nociceptive effects. A3AR agonists are emerging as promising candidates for neuropathic pain. Although their therapeutic potential has been demonstrated in diverse preclinical studies, no AR ligands have so far reached the market. To date, novel pharmacological approaches such as adenosine regulating agents and allosteric modulators have been proposed to improve efficacy and limit side effects enhancing the effect of endogenous adenosine. This review aims to provide an overview of the therapeutic potential of ligands interacting with ARs and the adenosinergic system for the treatment of acute and chronic pain.
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Choudhury H, Chellappan DK, Sengupta P, Pandey M, Gorain B. Adenosine Receptors in Modulation of Central Nervous System Disorders. Curr Pharm Des 2020; 25:2808-2827. [PMID: 31309883 DOI: 10.2174/1381612825666190712181955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022]
Abstract
The ubiquitous signaling nucleoside molecule, adenosine is found in different cells of the human body to provide its numerous pharmacological role. The associated actions of endogenous adenosine are largely dependent on conformational change of the widely expressed heterodimeric G-protein-coupled A1, A2A, A2B, and A3 adenosine receptors (ARs). These receptors are well conserved on the surface of specific cells, where potent neuromodulatory properties of this bioactive molecule reflected by its easy passage through the rigid blood-brainbarrier, to simultaneously act on the central nervous system (CNS). The minimal concentration of adenosine in body fluids (30-300 nM) is adequate to exert its neuromodulatory action in the CNS, whereas the modulatory effect of adenosine on ARs is the consequence of several neurodegenerative diseases. Modulatory action concerning the activation of such receptors in the CNS could be facilitated towards neuroprotective action against such CNS disorders. Our aim herein is to discuss briefly pathophysiological roles of adenosine on ARs in the modulation of different CNS disorders, which could be focused towards the identification of potential drug targets in recovering accompanying CNS disorders. Researches with active components with AR modulatory action have been extended and already reached to the bedside of the patients through clinical research in the improvement of CNS disorders. Therefore, this review consist of recent findings in literatures concerning the impact of ARs on diverse CNS disease pathways with the possible relevance to neurodegeneration.
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Affiliation(s)
- Hira Choudhury
- School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Dinesh K Chellappan
- School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Pallav Sengupta
- Department of Physiology, Faculty of Medicine, MA`HSA University, Kuala Lumpur, Malaysia
| | - Manisha Pandey
- School of Pharmacy, International Medical University, Bukit Jalil, Kuala Lumpur, Malaysia
| | - Bapi Gorain
- School of Pharmacy, Faculty of Health and Medical Science, Taylor's University, Subang Jaya, Selangor, Malaysia
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Kim K, Jeong W, Jun IG, Park JY. Antiallodynic and anti-inflammatory effects of intrathecal R-PIA in a rat model of vincristine-induced peripheral neuropathy. Korean J Anesthesiol 2020; 73:434-444. [PMID: 32046474 PMCID: PMC7533172 DOI: 10.4097/kja.19481] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 02/04/2020] [Indexed: 01/09/2023] Open
Abstract
Background Studies investigating the correlation between spinal adenosine A1 receptors and vincristine-induced peripheral neuropathy (VIPN) are limited. This study explored the role of intrathecal N6-(2-phenylisopropyl)-adenosine R-(-)isomer (R-PIA) in the rat model of VIPN. Methods Vincristine (100 μg/kg) was intraperitoneally administered for 10 days (two 5-day cycles with a 2-day pause) and VIPN was induced in rats. Pain was assessed by evaluating mechanical hyperalgesia, mechanical dynamic allodynia, thermal hyperalgesia, cold allodynia, and mechanical static allodynia. Biochemically, tumor necrosis factor-alpha (TNF-α) level and myeloperoxidase (MPO) activity were measured in the tissue from beneath the sciatic nerve. Results Vincristine administration resulted in the development of cold allodynia, mechanical hyperalgesia, thermal hyperalgesia, mechanical dynamic allodynia, and mechanical static allodynia. Intrathecally administered R-PIA (1.0 and 3.0 μg/10 μl) reversed vincristine-induced neuropathic pain (cold and mechanical static allodynia). The attenuating effect peaked 15 min after intrathecal administration of R-PIA after which it decreased until 180 min. However, pretreatment with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10 μg/10 μl) 15 min before intrathecal R-PIA administration significantly attenuated the antiallodynic effect of R-PIA. This antiallodynic effect of intrathecal R-PIA may be mediated through adenosine A1 receptors in the spinal cord. Intrathecally administered R-PIA also attenuated vincristine-induced increases in TNF-α level and MPO activity. However, pretreatment with intrathecal DPCPX significantly reversed this attenuation. Conclusions These results suggest that intrathecally administered R-PIA attenuates cold and mechanical static allodynia in a rat model of VIPN, partially due to its anti-inflammatory actions.
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Affiliation(s)
- Kyungmi Kim
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Wonyeong Jeong
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - In Gu Jun
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jong Yeon Park
- Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
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Souza A, Martins DF, Medeiros LF, Nucci-Martins C, Martins TC, Siteneski A, Caumo W, dos Santos ARS, Torres IL. Neurobiological mechanisms of antiallodynic effect of transcranial direct current stimulation (tDCS) in a mice model of neuropathic pain. Brain Res 2018; 1682:14-23. [DOI: 10.1016/j.brainres.2017.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 09/14/2017] [Accepted: 12/08/2017] [Indexed: 01/07/2023]
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Knezevic NN, Yekkirala A, Yaksh TL. Basic/Translational Development of Forthcoming Opioid- and Nonopioid-Targeted Pain Therapeutics. Anesth Analg 2017; 125:1714-1732. [PMID: 29049116 PMCID: PMC5679134 DOI: 10.1213/ane.0000000000002442] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Opioids represent an efficacious therapeutic modality for some, but not all pain states. Singular reliance on opioid therapy for pain management has limitations, and abuse potential has deleterious consequences for patient and society. Our understanding of pain biology has yielded insights and opportunities for alternatives to conventional opioid agonists. The aim is to have efficacious therapies, with acceptable side effect profiles and minimal abuse potential, which is to say an absence of reinforcing activity in the absence of a pain state. The present work provides a nonexclusive overview of current drug targets and potential future directions of research and development. We discuss channel activators and blockers, including sodium channel blockers, potassium channel activators, and calcium channel blockers; glutamate receptor-targeted agents, including N-methyl-D-aspartate, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid, and metabotropic receptors. Furthermore, we discuss therapeutics targeted at γ-aminobutyric acid, α2-adrenergic, and opioid receptors. We also considered antagonists of angiotensin 2 and Toll receptors and agonists/antagonists of adenosine, purine receptors, and cannabinoids. Novel targets considered are those focusing on lipid mediators and anti-inflammatory cytokines. Of interest is development of novel targeting strategies, which produce long-term alterations in pain signaling, including viral transfection and toxins. We consider issues in the development of druggable molecules, including preclinical screening. While there are examples of successful translation, mechanistically promising preclinical candidates may unexpectedly fail during clinical trials because the preclinical models may not recapitulate the particular human pain condition being addressed. Molecular target characterization can diminish the disconnect between preclinical and humans' targets, which should assist in developing nonaddictive analgesics.
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Affiliation(s)
- Nebojsa Nick Knezevic
- From the *Department of Anesthesiology, Advocate Illinois Masonic Medical Center Chicago, Illinois; Departments of †Anesthesiology and ‡Surgery, University of Illinois, Chicago, Illinois; §Department of Neurobiology, Harvard Medical School, and Boston Children's Hospital, Boston, Massachusetts; ‖Blue Therapeutics, Harvard Innovation Launch Lab, Allston, Massachusetts; and Departments of ¶Anesthesiology and #Pharmacology, University of California, San Diego, La Jolla, California
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Andoh T, Kobayashi N, Uta D, Kuraishi Y. Prophylactic topical paeoniflorin prevents mechanical allodynia caused by paclitaxel in mice through adenosine A 1 receptors. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2017; 25:1-7. [PMID: 28190463 DOI: 10.1016/j.phymed.2016.12.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 11/29/2016] [Accepted: 12/18/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND The chemotherapeutic agent paclitaxel (PTX) causes refractory peripheral neuropathy as a side effect. Prophylactic oral administration of the traditional herbal medicine Shakuyakukanzoto containing Paeoniae Radix and Glycyrrhizae Radix prevents the development of PTX-induced mechanical allodynia in mice via peripheral effects, mostly due to Paeoniae Radix. However, the bioactive component responsible for the prevention of PTX-induced neuropathic pain remains unknown. PURPOSE To determine whether a monoterpene glycoside paeoniflorin (PF), which is the principal bioactive constituent of Paeoniae Radix, has inhibitory effects on PTX-induced mechanical allodynia and investigate the underlying mechanisms. METHODS C57BL/6NCr mice received a single intraperitoneal injection of PTX and then were topically administered PF to the planar surface twice daily for 13 days. Mechanical allodynia was evaluated by the von Frey filament test, peripheral nerve activity was recorded using bipolar electrodes, and demyelination in peripheral nerves was analysed by electron microscopy. Schwann cell line LY-PPB6 pre-treated with PF and then treated with PTX was used to analyse the expression of the transcription factor CHOP, a marker of endoplasmic reticulum (ER) stress, by western blotting. RESULTS PTX caused mechanical allodynia and increased both spontaneous and mechanical stimuli-evoked peripheral nerve activities, whereas repetitive topical application of PF significantly attenuated PTX-induced allodynia, suppressed saphenous nerve firing, and inhibited demyelination in the plantar nerve. Moreover, in cultured Schwann cells, PF downregulated PTX-induced expression of CHOP, indicating the inhibition of ER stress. The attenuation of mechanical allodynia in mice and downregulation of CHOP levels in cell cultures was inhibited by adenosine A1 receptor (A1R) antagonist 8-cyclopentyl-1,3-diprooylxanrhine, suggesting the involvement of A1R in PF-associated analgesic effects. CONCLUSION These results suggest that prophylactic topical application of PF is effective in alleviating PTX-induced mechanical allodynia by protecting sensory nerves from demyelination via activation of the A1R.
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Affiliation(s)
- Tsugunobu Andoh
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan.
| | - Nao Kobayashi
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Daisuke Uta
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Yasushi Kuraishi
- Research Administration Division, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
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Yaksh TL, Fisher CJ, Hockman TM, Wiese AJ. Current and Future Issues in the Development of Spinal Agents for the Management of Pain. Curr Neuropharmacol 2017; 15:232-259. [PMID: 26861470 PMCID: PMC5412694 DOI: 10.2174/1570159x14666160307145542] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 12/02/2015] [Accepted: 02/05/2016] [Indexed: 11/22/2022] Open
Abstract
Targeting analgesic drugs for spinal delivery reflects the fact that while the conscious experience of pain is mediated supraspinally, input initiated by high intensity stimuli, tissue injury and/or nerve injury is encoded at the level of the spinal dorsal horn and this output informs the brain as to the peripheral environment. This encoding process is subject to strong upregulation resulting in hyperesthetic states and downregulation reducing the ongoing processing of nociceptive stimuli reversing the hyperesthesia and pain processing. The present review addresses the biology of spinal nociceptive processing as relevant to the effects of intrathecally-delivered drugs in altering pain processing following acute stimulation, tissue inflammation/injury and nerve injury. The review covers i) the major classes of spinal agents currently employed as intrathecal analgesics (opioid agonists, alpha 2 agonists; sodium channel blockers; calcium channel blockers; NMDA blockers; GABA A/B agonists; COX inhibitors; ii) ongoing developments in the pharmacology of spinal therapeutics focusing on less studied agents/targets (cholinesterase inhibition; Adenosine agonists; iii) novel intrathecal targeting methodologies including gene-based approaches (viral vectors, plasmids, interfering RNAs); antisense, and toxins (botulinum toxins; resniferatoxin, substance P Saporin); and iv) issues relevant to intrathecal drug delivery (neuraxial drug distribution), infusate delivery profile, drug dosing, formulation and principals involved in the preclinical evaluation of intrathecal drug safety.
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Affiliation(s)
- Tony L. Yaksh
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Casey J. Fisher
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Tyler M. Hockman
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
| | - Ashley J. Wiese
- University of California, San Diego, Anesthesia Research Lab 0818, 9500 Gilman Dr. LaJolla, CA 92093, USA
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Adenosine receptor targets for pain. Neuroscience 2016; 338:1-18. [DOI: 10.1016/j.neuroscience.2015.10.031] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/29/2015] [Accepted: 10/15/2015] [Indexed: 12/21/2022]
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Abstract
Chronic pain is one of the most debilitating and expensive diseases, yet current therapies are often insufficient in bringing about long-term relief. Further, many treatments for chronic pain also carry significant side effects. The molecule adenosine has long been identified as a potent inhibitor of nociceptive circuits in the spinal cord; however, the widespread expression of adenosine receptors in many organ systems has limited its use as an analgesic. Recently several 5' ectonucleotidases, including tissue non-specific alkaline phosphatase (TNAP), have been characterized for their ability to generate endogenous adenosine in nociceptive circuitry of the dorsal spinal cord. These ectonucleotidases have the ability to hydrolyze the endogenous pronociceptive nucleotides like adenosine triphosphate (ATP) into the antinociceptive nucleoside adenosine. This chapter discusses the role of TNAP and other ectonucleotidases in nociceptive circuits, and their potential as future targets of new therapeutics to treat chronic pain.
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Affiliation(s)
- Sarah E Street
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA,
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Central or peripheral delivery of an adenosine A1 receptor agonist improves mechanical allodynia in a mouse model of painful diabetic neuropathy. Neuroscience 2014; 285:312-23. [PMID: 25451280 DOI: 10.1016/j.neuroscience.2014.10.065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 10/28/2014] [Accepted: 10/31/2014] [Indexed: 02/07/2023]
Abstract
Diabetic peripheral neuropathy is a common complication of diabetes mellitus, and a significant proportion of individuals suffer debilitating pain that significantly affects their quality of life. Unfortunately, symptomatic treatment options have limited efficacy, and often carry significant risk of systemic adverse effects. Activation of the adenosine A1 receptor (A1R) by the analgesic small molecule adenosine has been shown to have antinociceptive benefits in models of inflammatory and neuropathic pain. The current study used a mouse model of painful diabetic neuropathy to determine the effect of diabetes on endogenous adenosine production, and if central or peripheral delivery of adenosine receptor agonists could alleviate signs of mechanical allodynia in diabetic mice. Diabetes was induced using streptozocin in male A/J mice. Mechanical withdrawal thresholds were measured weekly to characterize neuropathy phenotype. Hydrolysis of AMP into adenosine by ectonucleotidases was determined in the dorsal root ganglia (DRG) and spinal cord at 8 weeks post-induction of diabetes. AMP, adenosine and the specific A1R agonist, N(6)-cyclopentyladenosine (CPA), were administered both centrally (intrathecal) and peripherally (intraplantar) to determine the effect of activation of adenosine receptors on mechanical allodynia in diabetic mice. Eight weeks post-induction, diabetic mice displayed significantly decreased hydrolysis of extracellular AMP in the DRG; at this same time, diabetic mice displayed significantly decreased mechanical withdrawal thresholds compared to nondiabetic controls. Central delivery AMP, adenosine and CPA significantly improved mechanical withdrawal thresholds in diabetic mice. Surprisingly, peripheral delivery of CPA also improved mechanical allodynia in diabetic mice. This study provides new evidence that diabetes significantly affects endogenous AMP hydrolysis, suggesting that altered adenosine production could contribute to the development of painful diabetic neuropathy. Moreover, central and peripheral activation of A1R significantly improved mechanical sensitivity, warranting further investigation into this important antinociceptive pathway as a novel therapeutic option for the treatment of painful diabetic neuropathy.
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Traditional acupuncture triggers a local increase in adenosine in human subjects. THE JOURNAL OF PAIN 2013. [PMID: 23182227 DOI: 10.1016/j.jpain.2012.09.012] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
UNLABELLED Acupuncture is a form of Eastern medicine that has been practiced for centuries. Despite its long history and worldwide application, the biological mechanisms of acupuncture in relieving pain have been poorly defined. Recent studies in mice, however, demonstrate that acupuncture triggers increases in interstitial adenosine, which reduces the severity of chronic pain through adenosine A1 receptors, suggesting that adenosine-mediated antinociception contributes to the clinical benefits of acupuncture. We asked here whether acupuncture in human subjects is also linked to a local increase in interstitial adenosine concentration. We collected microdialysis samples of interstitial fluid before, during, and after delivering 30 minutes of conventional acupuncture in the Zusanli point in human subjects. The interstitial adenosine concentration increased significantly during acupuncture and remained elevated for 30 minutes after the acupuncture. Acupuncture-mediated adenosine release was not observed if acupuncture was not delivered in the Zusanli point or if the acupuncture needle was inserted, but not rotated. This study strengthens the role of adenosine in acupuncture-mediated antinociception by directly providing such evidence in humans. PERSPECTIVE This article presents further evidence of the role of adenosine in acupuncture-mediated antinociception by demonstrating that local adenosine concentrations increase in the acupoint in human subjects receiving traditional acupuncture.
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Yamaoka G, Horiuchi H, Morino T, Miura H, Ogata T. Different analgesic effects of adenosine between postoperative and neuropathic pain. J Orthop Sci 2013; 18:130-6. [PMID: 22996813 PMCID: PMC3553403 DOI: 10.1007/s00776-012-0302-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 08/16/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Adenosine is an endogenous neuromodulator in both the peripheral and central nervous systems. Adenosine inhibits pain signals by hyperpolarizing neuronal membrane. METHODS To clarify the effects of adenosine on pain signals, we tested intrathecal adenosine injection in two neuropathic pains (spinal cord compression and chronic constriction of sciatic nerve) and postoperative pain (plantar incision). RESULTS In all three kinds of pain models, significant shortening of withdrawal latencies to thermal stimulation were detected from 24 h to 1 week after the surgery. Significant improvements of pain sensation were observed in all three models after intrathecal injection of Cl-adenosine 24 h after surgery. At 72 h after surgery, intrathecal Cl-adenosine injection inhibited hyperalgesia in the two neuropathic pain models but not in the postoperative pain model. Adenosine A1R messenger RNA (mRNA) expression significantly decreased in the plantar incision model. Adenosine A1R protein levels also decreased compared with the other two models and normal control. CONCLUSIONS These results suggest that adenosine effectively inhibits pain signals in neuropathic pain but is less effective in postoperative pain because of the decrease in adenosine A1 receptors.
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Affiliation(s)
- Gotaro Yamaoka
- Spine Center, Ehime University Hospital, Tohon, Ehime 791-0295 Japan
| | - Hideki Horiuchi
- Spine Center, Ehime University Hospital, Tohon, Ehime 791-0295 Japan
| | - Tadao Morino
- Spine Center, Ehime University Hospital, Tohon, Ehime 791-0295 Japan
| | - Hiromasa Miura
- Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Tohon, Ehime 791-0295 Japan
| | - Tadanori Ogata
- Spine Center, Ehime University Hospital, Tohon, Ehime 791-0295 Japan
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Stepanović-Petrović RM, Micov AM, Tomić MA, Ugrešić ND. The Local Peripheral Antihyperalgesic Effect of Levetiracetam and Its Mechanism of Action in an Inflammatory Pain Model. Anesth Analg 2012; 115:1457-66. [DOI: 10.1213/ane.0b013e31826c7fc2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Liu J, Reid AR, Sawynok J. Spinal serotonin 5-HT7 and adenosine A1 receptors, as well as peripheral adenosine A1 receptors, are involved in antinociception by systemically administered amitriptyline. Eur J Pharmacol 2012; 698:213-9. [PMID: 23142373 DOI: 10.1016/j.ejphar.2012.10.042] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/26/2012] [Accepted: 10/31/2012] [Indexed: 01/05/2023]
Abstract
The present study explored a link between spinal 5-HT(7) and adenosine A(1) receptors in antinociception by systemic amitriptyline in normal and adenosine A(1) receptor knock-out mice using the 2% formalin test. In normal mice, antinociception by systemic amitriptyline 3mg/kg was blocked by intrathecal administration of the selective adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) 10 nmol. Blockade was also seen in adenosine A(1) receptor +/+ mice, but not in -/- mice lacking these receptors. In both normal and adenosine A(1) receptor +/+ mice, the selective 5-HT(7) receptor antagonist (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]pyrrolidine hydrochloride (SB269970) 3 μg blocked antinociception by systemic amitriptyline, but it did not prevent antinociception in adenosine A(1) receptor -/- mice. In normal mice, flinching was unaltered when the selective 5-HT(7) receptor agonist (2S)-(+)-5-(1,3,5-trimethylpyrazol-4-yl)-2-(dimethylamino)tetralin (AS-19) 20 μg was administered alone, but increased when co-administered intrathecally with DPCPX 10 nmol or SB269970 3 μg. Intrathecal AS-19 decreased flinching in adenosine A(1) receptor +/+ mice compared to -/- mice. Systemic amitriptyline appears to reduce nociception by activating spinal adenosine A(1) receptors secondarily to 5-HT(7) receptors. Spinal actions constitute only one aspect of antinociception by amitriptyline, as intraplantar DPCPX 10 nmol blocked antinociception by systemic amitriptyline in normal and adenosine A(1) receptor +/+, but not -/- mice. Adenosine A(1) receptor interactions are worthy of attention, as chronic oral caffeine (0.1, 0.3g/L, doses considered relevant to human intake levels) blocked antinociception by systemic amitriptyline in normal mice. In conclusion, adenosine A(1) receptors contribute to antinociception by systemic amitriptyline in both spinal and peripheral compartments.
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Affiliation(s)
- Jean Liu
- Department of Pharmacology, Dalhousie University, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada B3H 4R2
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Korboukh I, Hull-Ryde EA, Rittiner JE, Randhawa AS, Coleman J, Fitzpatrick BJ, Setola V, Janzen WP, Frye SV, Zylka MJ, Jin J. Orally active adenosine A(1) receptor agonists with antinociceptive effects in mice. J Med Chem 2012; 55:6467-77. [PMID: 22738238 DOI: 10.1021/jm3004834] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Adenosine A(1) receptor (A(1)AR) agonists have antinociceptive effects in multiple preclinical models of acute and chronic pain. Although numerous A(1)AR agonists have been developed, clinical applications of these agents have been hampered by their cardiovascular side effects. Herein we report a series of novel A(1)AR agonists, some of which are structurally related to adenosine 5'-monophosphate (5'-AMP), a naturally occurring nucleotide that itself activates A(1)AR. These novel compounds potently activate A(1)AR in several orthogonal in vitro assays and are subtype selective for A(1)AR over A(2A)AR, A(2B)AR, and A(3)AR. Among them, UNC32A (3a) is orally active and has dose-dependent antinociceptive effects in wild-type mice. The antinociceptive effects of 3a were completely abolished in A(1)AR knockout mice, revealing a strict dependence on A(1)AR for activity. The apparent lack of cardiovascular side effects when administered orally and high affinity (K(i) of 36 nM for the human A(1)AR) make this compound potentially suitable as a therapeutic.
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Affiliation(s)
- Ilia Korboukh
- Center for Integrative Chemical Biology and Drug Discovery, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Zeilhofer HU, Wildner H, Yévenes GE. Fast synaptic inhibition in spinal sensory processing and pain control. Physiol Rev 2012; 92:193-235. [PMID: 22298656 DOI: 10.1152/physrev.00043.2010] [Citation(s) in RCA: 260] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The two amino acids GABA and glycine mediate fast inhibitory neurotransmission in different CNS areas and serve pivotal roles in the spinal sensory processing. Under healthy conditions, they limit the excitability of spinal terminals of primary sensory nerve fibers and of intrinsic dorsal horn neurons through pre- and postsynaptic mechanisms, and thereby facilitate the spatial and temporal discrimination of sensory stimuli. Removal of fast inhibition not only reduces the fidelity of normal sensory processing but also provokes symptoms very much reminiscent of pathological and chronic pain syndromes. This review summarizes our knowledge of the molecular bases of spinal inhibitory neurotransmission and its organization in dorsal horn sensory circuits. Particular emphasis is placed on the role and mechanisms of spinal inhibitory malfunction in inflammatory and neuropathic chronic pain syndromes.
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Zylka MJ. Pain-relieving prospects for adenosine receptors and ectonucleotidases. Trends Mol Med 2011; 17:188-96. [PMID: 21236731 DOI: 10.1016/j.molmed.2010.12.006] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 12/12/2010] [Accepted: 12/15/2010] [Indexed: 01/09/2023]
Abstract
Adenosine receptor agonists have potent antinociceptive effects in diverse preclinical models of chronic pain. By contrast, the efficacy of adenosine and adenosine receptor agonists in treating pain in humans is unclear. Two ectonucleotidases that generate adenosine in nociceptive neurons were recently identified. When injected spinally, these enzymes have long-lasting adenosine A(1) receptor-dependent antinociceptive effects in inflammatory and neuropathic pain models. Furthermore, recent findings indicate that spinal adenosine A(2A) receptor activation can enduringly inhibit neuropathic pain symptoms. Collectively, these studies suggest the possibility of treating chronic pain in humans by targeting specific adenosine receptor subtypes in anatomically defined regions with agonists or with ectonucleotidases that generate adenosine.
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Affiliation(s)
- Mark J Zylka
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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Thorpe AJ, Clair A, Hochman S, Clemens S. Possible Sites of Therapeutic Action in Restless Legs Syndrome: Focus on Dopamine and α 2δ Ligands. Eur Neurol 2011; 66:18-29. [DOI: 10.1159/000328431] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 04/11/2011] [Indexed: 01/01/2023]
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Lima FO, Souza GR, Verri WA, Parada CA, Ferreira SH, Cunha FQ, Cunha TM. Direct blockade of inflammatory hypernociception by peripheral A1 adenosine receptors: involvement of the NO/cGMP/PKG/KATP signaling pathway. Pain 2010; 151:506-515. [PMID: 20813459 DOI: 10.1016/j.pain.2010.08.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 07/29/2010] [Accepted: 08/10/2010] [Indexed: 10/19/2022]
Abstract
Through activation of the A1 adenosine receptors (A1Rs) at both the central and peripheral level, adenosine produces antinociception in a wide range of tests. However, the mechanisms involved in the peripheral effect are still not fully understood. Therefore, the mechanisms by which peripheral activation of A1Rs reduces inflammatory hypernociception (a decrease in the nociceptive threshold) were addressed in the present study. Immunofluorescence of rat dorsal root ganglion revealed significant expression of A1Rs in primary sensory neurons associated with nociceptive pathways. Functionally, peripheral activation of A1Rs reduced inflammatory hypernociception because intraplantar (i.pl.) administration of an A1R antagonist (DPCPX) enhanced carrageenan-induced hypernociception. On the other hand, local (paw) administration of CPA (a selective A1R agonist) reversed mechanical hypernociception induced by carrageenan or by the directly acting hypernociceptive mediator prostaglandin E(2) (PGE(2)). Down-regulation of A1Rs expression in primary nociceptive neurons by intrathecal treatment with antisense oligodeoxinucleotides significantly reduced peripheral antinociceptive action of CPA. Direct blockade of PGE(2) inflammatory hypernociception by the activation of A1Rs depends on the nitric oxide/cGMP/Protein Kinase G/KATP signaling pathway because the peripheral antinociceptive effect of CPA was prevented by pretreatment with inhibitors of neuronal nitric oxide synthase (N-propyl-l-arginine), guanylyl cyclase (ODQ), and Protein Kinase G (KT5823) as well as with a KATP blocker (glibenclamide). However, this effect of CPA was not reduced by naloxone, excluding the participation of endogenous opioids. These results suggest that the peripheral activation of A1R plays a role in the regulation of inflammatory hypernociception by a mechanism that involves the NO/cGMP/PKG/KATP intracellular signaling pathway.
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Affiliation(s)
- Flávia Oliveira Lima
- Department of Pharmacology, Faculty of Medicine of Ribeirão Preto University of São Paulo, Avenida Bandeirantes, 3900, 14049-900 Ribeirão Preto, SP, Brazil Departamento de Patologia, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Rod. Celso Garcia Cid KM380 PR445, 86051-990 Londrina, PR, Brazil Biology Institute, State University of Campinas, UNICAMP, Campinas, São Paulo, Brazil
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Prostatic acid phosphatase reduces thermal sensitivity and chronic pain sensitization by depleting phosphatidylinositol 4,5-bisphosphate. J Neurosci 2010; 30:10282-93. [PMID: 20685973 DOI: 10.1523/jneurosci.2162-10.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Prostatic acid phosphatase (PAP) is expressed in nociceptive dorsal root ganglion (DRG) neurons, functions as an ectonucleotidase, and generates adenosine extracellularly. Here, we found that PAP inhibits noxious thermal sensitivity and sensitization that is associated with chronic pain through sustained activation of the adenosine A(1) receptor (A(1)R) and phospholipase C-mediated depletion of phosphatidylinositol 4,5-bisphosphate (PIP(2)). In mice, intrathecal injection of PAP reduced PIP(2) levels in DRGs, inhibited thermosensation through TRPV1, and enduringly reduced thermal hyperalgesia and mechanical allodynia caused by inflammation, nerve injury, and pronociceptive receptor activation. This included inhibitory effects on lysophosphatidic acid, purinergic (ATP), bradykinin, and protease-activated (thrombin) receptors. Conversely, PIP(2) levels were significantly elevated in DRGs from Pap(-/-) mice, and this correlated with enhanced thermal hyperalgesia and mechanical allodynia in Pap(-/-) mice. To directly test the importance of PIP(2) in nociception, we intrathecally injected PIP(2) into mice. This transiently (2 h) elevated PIP(2) levels in lumbar DRGs and transiently (2 h) enhanced thermosensation. Additionally, thermal hyperalgesia and mechanical allodynia were enduringly enhanced when PIP(2) levels were elevated coincident with injury/pronociceptive receptor stimulation. Nociceptive sensitization was not affected if PIP(2) levels were elevated in the absence of ongoing pronociceptive receptor stimulation. Together, our data suggest that PIP(2) levels in DRGs directly influence thermosensation and the magnitude of nociceptive sensitization. Moreover, our data suggest there is an underlying "phosphoinositide tone" that can be manipulated by an adenosine-generating ectonucleotidase. This tone regulates how effectively acute nociceptive insults promote the transition to chronic pain.
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35
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Li L, Hao JX, Fredholm BB, Schulte G, Wiesenfeld-Hallin Z, Xu XJ. Peripheral adenosine A2A receptors are involved in carrageenan-induced mechanical hyperalgesia in mice. Neuroscience 2010; 170:923-8. [PMID: 20678550 DOI: 10.1016/j.neuroscience.2010.07.045] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/19/2010] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
Here we studied the role of peripheral adenosine A(2A) receptors in mechanical hyperalgesia during inflammation using mice lacking the A(2A) receptors. Unilateral s.c. administration of the local inflammatory agent λ-carrageenan induced profound mechanical hyperalgesia 24 h after administration in the ipsilateral hind paw in wild-type mice. In homozygous mice lacking the A(2A) receptors, carrageenan-induced hyperalgesia was significantly reduced compared to wild type controls. The reduction in inflammatory hyperalgesia seen in A(2A) receptor knock-out mice was not associated with changes in paw edema. CGS 21680, a selective A(2A) receptor agonist, produced significantly more mechanical hyperalgesia in wild type females than in wild type males upon direct s.c. injection into the hindpaw whereas it had no effect upon systemic administration. The hyperalgesic effect of CGS 21680 was markedly reduced in the A(2A) knock-out mice of both sexes. Subcutaneous ZM-241,385, a selective A(2A) receptor antagonist, injected into the hindpaw reduced the mechanical hyperalgesia following carrageenan in female mice, but not in males. The results indicate that activation of peripheral adenosine A(2A) receptors during inflammation is associated with mechanical hyperalgesia, and that this effect is more prominent in females than in males.
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Affiliation(s)
- L Li
- Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz Väg 2, S-171 77 Stockholm, Sweden.
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36
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Sowa NA, Voss MK, Zylka MJ. Recombinant ecto-5'-nucleotidase (CD73) has long lasting antinociceptive effects that are dependent on adenosine A1 receptor activation. Mol Pain 2010; 6:20. [PMID: 20398264 PMCID: PMC2874211 DOI: 10.1186/1744-8069-6-20] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Accepted: 04/14/2010] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Ecto-5'-nucleotidase (NT5E, also known as CD73) hydrolyzes extracellular adenosine 5'-monophosphate (AMP) to adenosine in nociceptive circuits. Since adenosine has antinociceptive effects in rodents and humans, we hypothesized that NT5E, an enzyme that generates adenosine, might also have antinociceptive effects in vivo. RESULTS To test this hypothesis, we purified a soluble version of mouse NT5E (mNT5E) using the baculovirus expression system. Recombinant mNT5E hydrolyzed AMP in biochemical assays and was inhibited by alpha,beta-methylene-adenosine 5'-diphosphate (alpha,beta-me-ADP; IC50 = 0.43 microM), a selective inhibitor of NT5E. mNT5E exhibited a dose-dependent thermal antinociceptive effect that lasted for two days when injected intrathecally in wild-type mice. In addition, mNT5E had thermal antihyperalgesic and mechanical antiallodynic effects that lasted for two days in the complete Freund's adjuvant (CFA) model of inflammatory pain and the spared nerve injury (SNI) model of neuropathic pain. In contrast, mNT5E had no antinociceptive effects when injected intrathecally into adenosine A1 receptor (A1R, Adora1) knockout mice. CONCLUSION Our data indicate that the long lasting antinociceptive effects of mNT5E are due to hydrolysis of AMP followed by activation of A1R. Moreover, our data suggest recombinant NT5E could be used to treat chronic pain and to study many other physiological processes that are regulated by NT5E.
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Affiliation(s)
- Nathaniel A Sowa
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina, CB #7545, Chapel Hill, North Carolina 27599, USA
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Schmidt AP, Böhmer AE, Schallenberger C, Antunes C, Tavares RG, Wofchuk ST, Elisabetsky E, Souza DO. Mechanisms involved in the antinociception induced by systemic administration of guanosine in mice. Br J Pharmacol 2010; 159:1247-63. [PMID: 20132210 DOI: 10.1111/j.1476-5381.2009.00597.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE It is well known that adenine-based purines exert multiple effects on pain transmission. However, less attention has been given to the potential effects of guanine-based purines on pain transmission. The aim of this study was to investigate the effects of intraperitoneal (i.p.) and oral (p.o.) administration of guanosine on mice pain models. Additionally, investigation into the mechanisms of action of guanosine, its potential toxicity and cerebrospinal fluid (CSF) purine levels were also assessed. EXPERIMENTAL APPROACH Mice received an i.p. or p.o. administration of vehicle (0.1 mM NaOH) or guanosine (up to 240 mg x kg(-1)) and were evaluated in several pain models. KEY RESULTS Guanosine produced dose-dependent antinociceptive effects in the hot-plate, glutamate, capsaicin, formalin and acetic acid models, but it was ineffective in the tail-flick test. Additionally, guanosine produced a significant inhibition of biting behaviour induced by i.t. injection of glutamate, AMPA, kainate and trans-ACPD, but not against NMDA, substance P or capsaicin. The antinociceptive effects of guanosine were prevented by selective and non-selective adenosine receptor antagonists. Systemic administration of guanosine (120 mg x kg(-1)) induced an approximately sevenfold increase on CSF guanosine levels. Guanosine prevented the increase on spinal cord glutamate uptake induced by intraplantar capsaicin. CONCLUSIONS AND IMPLICATIONS This study provides new evidence on the mechanism of action of the antinociceptive effects after systemic administration of guanosine. These effects seem to be related to the modulation of adenosine A(1) and A(2A) receptors and non-NMDA glutamate receptors.
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Affiliation(s)
- A P Schmidt
- Department of Biochemistry, ICBS, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
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Zylka MJ, Sowa NA, Taylor-Blake B, Twomey MA, Herrala A, Voikar V, Vihko P. Prostatic acid phosphatase is an ectonucleotidase and suppresses pain by generating adenosine. Neuron 2008; 60:111-22. [PMID: 18940592 DOI: 10.1016/j.neuron.2008.08.024] [Citation(s) in RCA: 139] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 07/28/2008] [Accepted: 08/22/2008] [Indexed: 01/06/2023]
Abstract
Thiamine monophosphatase (TMPase, also known as fluoride-resistant acid phosphatase) is a classic histochemical marker of small-diameter dorsal root ganglia neurons. The molecular identity of TMPase is currently unknown. We found that TMPase is identical to the transmembrane isoform of prostatic acid phosphatase (PAP), an enzyme with unknown molecular and physiological functions. We then found that PAP knockout mice have normal acute pain sensitivity but enhanced sensitivity in chronic inflammatory and neuropathic pain models. In gain-of-function studies, intraspinal injection of PAP protein has potent antinociceptive, antihyperalgesic, and antiallodynic effects that last longer than the opioid analgesic morphine. PAP suppresses pain by functioning as an ecto-5'-nucleotidase. Specifically, PAP dephosphorylates extracellular adenosine monophosphate (AMP) to adenosine and activates A1-adenosine receptors in dorsal spinal cord. Our studies reveal molecular and physiological functions for PAP in purine nucleotide metabolism and nociception and suggest a novel use for PAP in the treatment of chronic pain.
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Affiliation(s)
- Mark J Zylka
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina, CB #7545, Chapel Hill, NC 27599, USA.
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Tuboly G, Kekesi G, Nagy E, Benedek G, Horvath G. The antinociceptive interaction of anandamide and adenosine at the spinal level. Pharmacol Biochem Behav 2008; 91:374-9. [PMID: 18760296 DOI: 10.1016/j.pbb.2008.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 06/30/2008] [Accepted: 08/05/2008] [Indexed: 01/16/2023]
Abstract
Both anandamide and adenosine have significant roles in pain mechanisms, but no data are available concerning their interaction at the spinal level. The goal of this study was to determine how adenosine and the adenosine receptor antagonist caffeine affect the antinociceptive effect of anandamide. The pain sensitivity was assessed by the acute tail-flick test and by paw withdrawal test after carrageenan-induced inflammation. The substances were administered intrathecally to male Wistar rats. Anandamide alone (1, 30 and 100 microg) dose-dependently decreased the hyperalgesia, however it had low potency in the tail-flick test. Neither adenosine (100 microg) nor caffeine (400 microg) alone changed the pain sensitivity markedly. Their combination caused a short-lasting antihyperalgesia, but it did not influence the tail-flick latency. Both adenosine and caffeine decreased the antihyperalgesic potential of 100 microg anandamide, while adenosine-caffeine pretreatment temporarily enhanced its effect. As regards acute heat pain sensitivity, no combination with anandamide influenced the effect of anandamide. These findings provide new data concerning the interaction between two endogenous ligands and caffeine. Since these substances may exert effects on several receptors and/or systems, their interaction in vivo must be very complex and the net outcome after their coadministration could not been predicted from the in vitro results.
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Affiliation(s)
- Gabor Tuboly
- Department of Physiology, Faculty of Medicine, University of Szeged, P.O. Box 427, H-6701 Szeged, Hungary
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Hughes AS, Averill S, King VR, Molander C, Shortland PJ. Neurochemical characterization of neuronal populations expressing protein kinase C gamma isoform in the spinal cord and gracile nucleus of the rat. Neuroscience 2008; 153:507-17. [PMID: 18387748 DOI: 10.1016/j.neuroscience.2008.01.082] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 01/23/2008] [Accepted: 01/23/2008] [Indexed: 10/22/2022]
Abstract
Protein kinase C gamma (PKCgamma) is widely distributed throughout the CNS and is thought to play a role in long term hyper-excitability in nociceptive neurones. Here, we provide the first report of PKCgamma cells in the dorsal column nuclei of the adult rat. Retrograde labeling of PKCgamma cells from the thalamus with choleragenoid revealed that 25% of the PKCgamma positive gracile cells projected to the thalamus. Further, we have characterized the distribution of PKCgamma within gracile nucleus in terms of colocalization with various neurotransmitter receptors or enzymes and calcium binding proteins, and compared this with PKCgamma colocalization in cells of laminae I-III of the spinal cord. We show that approximately 90% of the PKCgamma cells in the gracile nucleus and 60% in the dorsal horn were immuno-positive for the AMPA receptor subunit glutamate 2/3 (GluR2/3). Little coexpression was seen with neurokinin 1 receptor, nitric oxide synthase (NOS) and the AMPA receptor subunit GluR1, markers of distinct neuronal subpopulations. In the spinal cord, a quarter of PKCgamma cells expressed calbindin, but very few cells did so in the gracile nucleus. Electrical stimulation at c-fiber strength of the normal or injured sciatic nerve was used to induce c-fos as a marker of postsynaptic activation in the spinal cord and gracile nucleus. Quantitative analysis of the number of PKCgamma positive gracile cells that expressed also c-fos increased from none to 24% after injury, indicating an alteration in the sensory activation pattern in these neurones after injury. C-fos was not induced in inner lamina II following c-fiber electrical stimulation of the intact or axotomized sciatic nerve, indicating no such plasticity at the spinal cord level. As dorsal column nuclei cells may contribute to allodynia after peripheral nerve injury, pharmacological modulation of PKCgamma activity may therefore be a possible way to ameliorate neuropathic pain after peripheral nerve injury.
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Affiliation(s)
- A S Hughes
- Department of Neuroscience, Institute of Molecular and Cellular Science, Bart's and The London School of Medicine and Dentistry, 4 Newark Street, London, UK
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Mousa SA, Bopaiah CP, Richter JF, Yamdeu RS, Schäfer M. Inhibition of inflammatory pain by CRF at peripheral, spinal and supraspinal sites: involvement of areas coexpressing CRF receptors and opioid peptides. Neuropsychopharmacology 2007; 32:2530-42. [PMID: 17375137 DOI: 10.1038/sj.npp.1301393] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is conflicting evidence on the antinociceptive effects of corticotropin-releasing factor (CRF) along the neuraxis of pain transmission and the responsible anatomical sites of CRF's action at the level of the brain, spinal cord and periphery. In an animal model of tonic pain, that is, Freunds complete adjuvant (FCA) hindpaw inflammation, we systematically investigated CRF's ability to modulate inflammatory pain at those three levels of pain transmission by algesiometry following the intracerebroventricular, intrathecal, and intraplantar application of low, systemically inactive doses of CRF. At each level, CRF elicits potent antinociceptive effects, which are dose dependent and antagonized by local, but not systemic CRF receptor antagonist alpha-helical CRF indicating CRF receptor specificity. Consistently, we have identified by immunohistochemistry multiple brain areas, inhibitory interneurons within the dorsal horn of the spinal cord as well as immune cells within subcutaneous tissue--but not peripheral sensory neurons--that coexpress both CRF receptors and opioid peptides. In line with these anatomical findings, local administration of CRF together with the opioid receptor antagonist naloxone dose-dependently reversed CRF's antinociceptive effects at each of these three levels of pain transmission. Therefore, local application of low, systemically inactive doses of CRF at the level of the brain, spinal cord and periphery inhibits tonic inflammatory pain most likely through an activation of CRF receptors on cells that coexpress opioid peptides which results in opioid-mediated pain inhibition. Future studies have to delineate whether endogenous CRF at these three levels contributes to the body's response to cope with the stressful stimulus pain in an opioid-mediated manner.
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Affiliation(s)
- Shaaban A Mousa
- Klinik für Anaesthesiologie und operative Intensivmedizin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
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Martin TJ, Eisenach JC, Misler J, Childers SR. Chronic activation of spinal adenosine A1 receptors results in hypersensitivity. Neuroreport 2007; 17:1619-22. [PMID: 17001280 DOI: 10.1097/01.wnr.0000239949.37825.e9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Spinally administered adenosine reduces hypersensitivity in animals and humans with nerve injury, but also causes transient pain in humans and reduces tonic inhibition in spinal neurons. Nerve injury results in increased tonic spinal cord adenosine A1 receptor activation, consistent with a role for adenosine to generate hypersensitivity. Here, we demonstrate that chronic intrathecal adenosine induces hypersensitivity in normal animals and that chronic blockade of spinal adenosine A1 receptors by the A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine partially prevents nerve injury-induced hypersensitivity. In contrast, chronic blockade of spinal adenosine A1 receptors failed to reduce increased tonic G-protein signaling in the spinal cord after nerve injury. These data support a role for chronic adenosine A1 receptor stimulation after nerve injury to result in hypersensitivity.
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Affiliation(s)
- Thomas J Martin
- Department of Anesthesiology and Physiology/Pharmacology and the Center for the Study of Pharmacologic Plasticity in the Presence of Pain, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA
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Aubel B, Kayser V, Farré A, Hamon M, Bourgoin S. Evidence for adenosine- and serotonin-mediated antihyperalgesic effects of cizolirtine in rats suffering from diabetic neuropathy. Neuropharmacology 2007; 52:487-96. [PMID: 17027046 DOI: 10.1016/j.neuropharm.2006.08.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2005] [Revised: 07/31/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
Cizolirtine is a novel non-opioid drug which demonstrated antinociceptive activity in numerous pain models in rodents. Yet, its mechanism of action remains unknown. Several lines of evidence support the idea that adenosine (ADO) and serotonin (5-HT) modulate nociceptive signaling. Our study aimed at investigating whether these neuroactive molecules could be implicated in the mechanism of action of cizolirtine. Cizolirtine-induced antihyperalgesia was compared before and after pretreatment with ADO A(1)-A(2A) and 5-HT(1B/1D) receptor ligands in rats rendered diabetic by streptozotocin pretreatment and suffering from neuropathic pain. Cizolirtine alone (30-80 mg/kg, i.p.) significantly increased mechanical nociceptive thresholds. Acute pretreatment with the A(1)-A(2A) receptor antagonist caffeine (5 mg/kg, i.p.) or the 5-HT(1B/1D) receptor antagonist GR-127,935 (3 mg/kg, i.p.) significantly reduced the antihyperalgesic effects of cizolirtine. Conversely, cizolirtine-induced antihyperalgesia was promoted by pretreatment with either the selective A(1) receptor agonist CPA (0.3 mg/kg, i.p.) or the selective 5-HT(1B) receptor agonist CP-94,253 (3mg/kg, i.p.), and this potentiation was totally prevented by acute pretreatment with respective antagonists. Interestingly, A(1) receptor blockade by DPCPX inhibited the promoting effect of CP-94,253 on cizolirtine-induced antihyperalgesia, suggesting that the adenosine A(1)-mediated step takes place downstream the serotonin 5-HT(1B)-mediated step in the neurobiological mechanisms underlying cizolirtine action.
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Affiliation(s)
- Bertrand Aubel
- INSERM, U677, and Université Pierre et Marie Curie-Paris6, Faculté de Médecine Pierre et Marie Curie, Site Pitié-Salpétrière, UMR S677, 91 Boulevard de l'Hôpital, Paris F-75013, France
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44
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Abstract
Adenosine and ATP, via P1 and P2 receptors respectively, can modulate pain transmission under physiological, inflammatory, and neuropathic pain conditions. Such influences reflect peripheral and central actions and effects on neurons as well as other cell types. In general, adenosine A1 receptors produce inhibitory effects on pain in a number of preclinical models and are a focus of attention. In humans, i.v. infusions of adenosine reduce some aspects of neuropathic pain and can reduce postoperative pain. For P2X receptors, there is a significant body of information indicating that inhibition of P2X3 receptors may be useful for relieving inflammatory and neuropathic pain. More recently, data have begun to emerge implicating P2X4, P2X7 and P2Y receptors in aspects of pain transmission. Both P1 and P2 receptors may represent novel targets for pain relief.
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Affiliation(s)
- J Sawynok
- Department of Pharmacology, Dalhousie University, Halifax NS, B3H 1X5, Canada.
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Back SA, Craig A, Luo NL, Ren J, Akundi RS, Ribeiro I, Rivkees SA. Protective effects of caffeine on chronic hypoxia-induced perinatal white matter injury. Ann Neurol 2006; 60:696-705. [PMID: 17044013 DOI: 10.1002/ana.21008] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Periventricular white matter injury (PWMI) is the major cause of cerebral palsy and cognitive impairment in prematurely born infants. PWMI is characterized by reductions in cerebral myelination and cerebrocortical volumes and is associated with secondary ventriculomegaly. In neonatal rodents, these features of PWMI can be induced by rearing in chronic hypoxia or by activation of A1 adenosine receptors. We determined: (1) whether altered maturation or development of one or more oligodendrocyte (OL) lineage stages plays a role in the pathogenesis of the myelination disturbances associated with exposure to chronic hypoxia, and (2) whether blockade of A1 adenosine receptor action with the adenosine antagonist caffeine can prevent hypoxia-induced white matter injury. METHODS Ventriculomegaly and reduced cerebral myelination were generated in mice reared in hypoxia (10% oxygen) from postnatal days 3 (P3) through 12. RESULTS Hypomyelination was related to abnormal OL lineage progression and a reduction in the OL progenitor pool. Myelination was enhanced and ventriculomegaly reduced in hypoxia-exposed neonatal pups treated with caffeine from P3 to P12. INTERPRETATION These observations support that hypoxia inhibits OL maturation and that caffeine administration during early postnatal development may have utility in the prevention of PWMI.
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MESH Headings
- Adenosine/antagonists & inhibitors
- Adenosine/metabolism
- Adenosine A1 Receptor Antagonists
- Animals
- Animals, Newborn
- Asphyxia Neonatorum/drug therapy
- Asphyxia Neonatorum/pathology
- Asphyxia Neonatorum/physiopathology
- Brain/drug effects
- Brain/pathology
- Brain/physiopathology
- Caffeine/pharmacology
- Caffeine/therapeutic use
- Cell Differentiation/drug effects
- Cell Differentiation/physiology
- Cell Lineage/drug effects
- Cell Lineage/physiology
- Chronic Disease
- Disease Models, Animal
- Female
- Humans
- Hypoxia, Brain/drug therapy
- Hypoxia, Brain/pathology
- Hypoxia, Brain/physiopathology
- Infant, Newborn
- Leukomalacia, Periventricular/drug therapy
- Leukomalacia, Periventricular/pathology
- Leukomalacia, Periventricular/physiopathology
- Mice
- Mice, Inbred C57BL
- Nerve Fibers, Myelinated/drug effects
- Nerve Fibers, Myelinated/pathology
- Neuroprotective Agents/pharmacology
- Neuroprotective Agents/therapeutic use
- Oligodendroglia/drug effects
- Oligodendroglia/metabolism
- Oligodendroglia/pathology
- Pregnancy
- Receptor, Adenosine A1/metabolism
- Stem Cells/drug effects
- Stem Cells/metabolism
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Affiliation(s)
- Stephen A Back
- Department of Pediatrics, Oregon Health & Science University, Portland, OR, USA
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King AE, Ackley MA, Cass CE, Young JD, Baldwin SA. Nucleoside transporters: from scavengers to novel therapeutic targets. Trends Pharmacol Sci 2006; 27:416-25. [PMID: 16820221 DOI: 10.1016/j.tips.2006.06.004] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 04/18/2006] [Accepted: 06/19/2006] [Indexed: 11/26/2022]
Abstract
Hydrophilic purine and pyrimidine nucleosides rely on specialized carrier proteins for their membrane translocation. The recent identification of two gene families encoding equilibrative and concentrative nucleoside transporters in mammals and other organisms has provided the essential breakthrough to a more complete understanding of the biological significance of nucleoside transport. Although nucleoside salvage is a primary function of these proteins, recent data indicate functions beyond metabolic recycling. In brain and spinal cord, for example, nucleoside transporters have the potential to regulate synaptic levels of neuroactive purines such as adenosine and, thereby, indirectly modulate physiological processes through G-protein-coupled purine P1 receptors. As described in this review, recent research indicates novel putative functions for CNS nucleoside transporters in sleep, arousal, drug and alcohol addiction, nociception and analgesia. The therapeutic use of nucleoside analogue drugs and nucleoside transporter inhibitors in viral, neoplastic, cardiovascular and infectious disease is also described.
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Affiliation(s)
- Anne E King
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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Huang HY, Cheng JK, Shih YH, Chen PH, Wang CL, Tsaur ML. Expression of A-type K channel alpha subunits Kv 4.2 and Kv 4.3 in rat spinal lamina II excitatory interneurons and colocalization with pain-modulating molecules. Eur J Neurosci 2006; 22:1149-57. [PMID: 16176357 DOI: 10.1111/j.1460-9568.2005.04283.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Voltage-gated K(+) channel alpha subunits Kv 4.2 and Kv 4.3 are the major contributors of somatodendritic A-type K(+) currents in many CNS neurons. A recent hypothesis suggests that Kv 4 subunits may be involved in pain modulation in dorsal horn neurons. However, whether Kv 4 subunits are expressed in dorsal horn neurons remains unknown. Using immunohistochemistry, we found that Kv 4.2 and Kv 4.3 immunoreactivity was concentrated in the superficial dorsal horn, mainly in lamina II. Both Kv 4.2 and Kv 4.3 appeared on many rostrocaudally orientated dendrites, whereas Kv 4.3 could be also detected from certain neuronal somata. Kv 4.3(+) neurons were a subset of excitatory inerneurons with calretinin(+)/calbindin(-)/PKCgamma(-) markers, and a fraction of them expressed micro-opioid receptors. Kv 4.3(+) neurons also expressed ERK 2 and mGluR 5, which are molecules related to the induction of central sensitization, a mechanism mediating nociceptive plasticity. Together with the expression of Kv 4.3 in VR 1(+) DRG neurons, our data suggest that Kv C4 subunits could be involved in pain modulation.
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Affiliation(s)
- Hsin-Yi Huang
- Institute of Neuroscience, National Yang-Ming University, Brain Research Centre, University System of Taiwan, Taipei, Taiwan 112, Republic of China
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Governo RJM, Deuchars J, Baldwin SA, King AE. Localization of the NBMPR-sensitive equilibrative nucleoside transporter, ENT1, in the rat dorsal root ganglion and lumbar spinal cord. Brain Res 2005; 1059:129-38. [PMID: 16226730 DOI: 10.1016/j.brainres.2005.08.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 08/05/2005] [Accepted: 08/08/2005] [Indexed: 10/25/2022]
Abstract
ENT1 is an equilibrative nucleoside transporter that enables trans-membrane bi-directional diffusion of biologically active purines such as adenosine. In spinal cord dorsal horn and in sensory afferent neurons, adenosine acts as a neuromodulator with complex pro- and anti-nociceptive actions. Although uptake and release mechanisms for adenosine are believed to exist in both the dorsal horn and sensory afferent neurons, the expression profile of specific nucleoside transporter subtypes such as ENT1 is not established. In this study, immunoblot analysis with specific ENT1 antibodies (anti-rENT1(227-290) or anti-hENT1(227-290)) was used to reveal the expression of ENT1 protein in tissue homogenates of either adult rat dorsal horn or dorsal root ganglia (DRG). Immunoperoxidase labeling with ENT1 antibodies produced specific staining in dorsal horn which was concentrated over superficial laminae, especially the substantia gelatinosa (lamina II). Immunofluorescence double-labeling revealed a punctate pattern for ENT1 closely associated, in some instances, with cell bodies of either neurons (confirmed with NeuN) or glia (confirmed with CNPase). Electron microscopy analysis of ENT1 expression in lamina II indicated its presence within pre- and post-synaptic elements, although a number of other structures, including myelinated and unmyelinated, axons were also labeled. In sensory ganglia, ENT1 was localized to a high proportion of cell bodies of all sizes that co-expressed substance P, IB4 or NF, although ENT1 was most highly expressed in the peptidergic population. These data provide the first detailed account of the expression and cellular distribution of ENT1 in rat dorsal horn and sensory ganglia. The functional significance of ENT1 expression with regard to the homeostatic regulation of adenosine at synapses remains to be established.
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49
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Wu WP, Hao JX, Halldner L, Lövdahl C, DeLander GE, Wiesenfeld-Hallin Z, Fredholm BB, Xu XJ. Increased nociceptive response in mice lacking the adenosine A1 receptor. Pain 2005; 113:395-404. [PMID: 15661449 DOI: 10.1016/j.pain.2004.11.020] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 11/05/2004] [Accepted: 11/22/2004] [Indexed: 11/28/2022]
Abstract
The role of the adenosine A1 receptor in nociception was assessed using mice lacking the A1 receptor (A1R-/-) and in rats. Under normal conditions, the A1R-/- mice exhibited moderate heat hyperalgesia in comparison to the wild-type mice (A1R+/+). The mechanical and cold sensitivity were unchanged. The antinociceptive effect of morphine given intrathecally (i.t.), but not systemically, was reduced in A1R-/- mice and this reduction in the spinal effect of morphine was not associated with a decrease in binding of the mu-opioid ligand DAMGO in the spinal cord. A1R-/- mice also exhibited hypersensitivity to heat, but not mechanical stimuli, after localized inflammation induced by carrageenan. In mice with photochemically induced partial sciatic nerve injury, the neuropathic pain-like behavioral response to heat or cold stimulation were significantly increased in the A1R-/-mice. Peripheral nerve injury did not change the level of adenosine A1 receptor in the dorsal spinal cord in rats and i.t. administration of R-PIA effectively alleviated pain-like behaviors after partial nerve injury in rats and in C57/BL/6 mice. Taken together, these data suggest that the adenosine A1 receptor plays a physiological role in inhibiting nociceptive input at the spinal level in mice. The C-fiber input mediating noxious heat is inhibited more than other inputs. A1 receptors also contribute to the antinociceptive effect of spinal morphine. Selective A1 receptor agonists may be tested clinically as analgesics, particularly under conditions of neuropathic pain.
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Affiliation(s)
- Wei-Ping Wu
- Department of Neurotec, Division of Clinical Neurophysiology, Karolinska Institutet, Karolinska University Hospital-Huddinge, S-141 86 Stockholm, Sweden Department of Physiology and Pharmacology, Section of Molecular Neuropharmacology, Karolinska Institutet, S-141 86 Stockholm, Sweden Department of Pharmacology, College of Pharmacy, Oregon State University, Corvallis, OR 97311-3507, USA
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50
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Fredholm BB, Chen JF, Cunha RA, Svenningsson P, Vaugeois JM. Adenosine and Brain Function. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 63:191-270. [PMID: 15797469 DOI: 10.1016/s0074-7742(05)63007-3] [Citation(s) in RCA: 494] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet Stockholm, Sweden
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