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Wu J, Jin M, Tran Q, Kim M, Kim SI, Shin J, Park H, Shin N, Kang H, Shin HJ, Lee SY, Cui SB, Lee CJ, Lee WH, Kim DW. Employing the sustained-release properties of poly(lactic-co-glycolic acid) nanoparticles to reveal a novel mechanism of sodium-hydrogen exchanger 1 in neuropathic pain. Transl Res 2024; 263:53-72. [PMID: 37678757 DOI: 10.1016/j.trsl.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 08/16/2023] [Accepted: 09/01/2023] [Indexed: 09/09/2023]
Abstract
Neuropathic pain is caused by injury or disease of the somatosensory system, and its course is usually chronic. Several studies have been dedicated to investigating neuropathic pain-related targets; however, little attention has been paid to the persistent alterations that these targets, some of which may be crucial to the pathophysiology of neuropathic pain. The present study aimed to identify potential targets that may play a crucial role in neuropathic pain and validate their long-term impact. Through bioinformatics analysis of RNA sequencing results, we identified Slc9a1 and validated the reduced expression of sodium-hydrogen exchanger 1 (NHE1), the protein that Slc9a1 encodes, in the spinal nerve ligation (SNL) model. Colocalization analysis revealed that NHE1 is primarily co-localized with vesicular glutamate transporter 2-positive neurons. In vitro experiments confirmed that poly(lactic-co-glycolic acid) nanoparticles loaded with siRNA successfully inhibited NHE1 in SH-SY5Y cells, lowered intracellular pH, and increased intracellular calcium concentrations. In vivo experiments showed that sustained suppression of spinal NHE1 expression by siRNA-loaded nanoparticles resulted in delayed hyperalgesia in naïve and SNL model rats, whereas amiloride-induced transient suppression of NHE1 expression yielded no significant changes in pain sensitivity. We identified Slc9a1, which encodes NHE1, as a key gene in neuropathic pain. Utilizing the sustained release properties of nanoparticles enabled us to elucidate the chronic role of decreased NHE1 expression, establishing its significance in the mechanisms of neuropathic pain.
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Affiliation(s)
- Junhua Wu
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Neurology, Yanji Hospital, Yanji, China
| | - Meiling Jin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Quangdon Tran
- Molecular Biology Laboratory, Department of Medical Laboratories, Hai Phong International Hospital, Hai Phong City, Vietnam
| | - Minwoo Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Song I Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Juhee Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Hyewon Park
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Nara Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Hyunji Kang
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Hyo Jung Shin
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Sun Yeul Lee
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anesthesia and Pain Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Song-Biao Cui
- Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, China
| | - C Justin Lee
- Center for Cognition and Sociality, Life Science Cluster, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Won Hyung Lee
- Department of Anesthesia and Pain Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea
| | - Dong Woon Kim
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon, Republic of Korea; Department of Anatomy and Cell Biology, Brain Research Institute, Chungnam National University School of Medicine, Daejeon, Republic of Korea.
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Yuan Z, Miao L, Zhang S, Li H, Li G, Zhang G. The role of acid-sensing ion channels in monosodium urate-induced gouty pain in mice. Pflugers Arch 2024; 476:101-110. [PMID: 37770586 DOI: 10.1007/s00424-023-02862-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 06/25/2023] [Accepted: 09/19/2023] [Indexed: 09/30/2023]
Abstract
Acid-sensing ion channels (ASICs) in dorsal root ganglion (DRG) neurons play an important role in inflammatory pain. The objective of this study is to observe the regulatory role of ASICs in monosodium urate (MSU) crystal-induced gout pain and explore the basis for ASICs in DRG neurons as a target for gout pain treatment. The gout arthritis model was induced by injecting MSU crystals into the ankle joint of mice. The circumference of the ankle joint was used to evaluate the degree of swelling; the von Frey filaments were used to determine the withdrawal threshold of the paw. ASIC currents and action potentials (APs) were recorded by patch clamp technique in DRG neurons. The results displayed that injecting MSU crystals caused ankle edema and mechanical hyperalgesia of the paw, which was relieved after amiloride treatment. The ASIC currents in DRG neurons were increased to a peak on the second day after injecting MSU crystals, which were decreased after amiloride treatment. MSU treatment increased the current density of ASICs in different diameter DRG cells. MSU treatment does not change the characteristics of AP. The results suggest that ASICs in DRG neurons participate in MSU crystal-induced gout pain.
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Affiliation(s)
- Ziqi Yuan
- Department of Clinical Pharmacy, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, China
| | - Lurong Miao
- Department of Clinical Pharmacy, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, China
| | - Shijia Zhang
- School of Pharmacy, Xuzhou Medical University, Xuzhou, 221100, China
| | - Hanhan Li
- Department of Clinical Pharmacy, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, China
| | - Guang Li
- Key Laboratory of Medical Electrophysiology, Ministry of Education, Institute of Cardiovascular Research of Southwest Medical University, Luzhou, 6463000, China
| | - Guangqin Zhang
- Department of Clinical Pharmacy, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing, 210009, China.
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Liu H, Lauzadis J, Gunaratna K, Sipple E, Kaczocha M, Puopolo M. Inhibition of T-Type Calcium Channels With TTA-P2 Reduces Chronic Neuropathic Pain Following Spinal Cord Injury in Rats. THE JOURNAL OF PAIN 2023; 24:1681-1695. [PMID: 37169156 DOI: 10.1016/j.jpain.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 04/03/2023] [Accepted: 05/02/2023] [Indexed: 05/13/2023]
Abstract
Spinal cord injury (SCI)-induced neuropathic pain (SCI-NP) develops in up to 60 to 70% of people affected by traumatic SCI, leading to a major decline in quality of life and increased risk for depression, anxiety, and addiction. Gabapentin and pregabalin, together with antidepressant drugs, are commonly prescribed to treat SCI-NP, but their efficacy is unsatisfactory. The limited efficacy of current pharmacological treatments for SCI-NP likely reflects our limited knowledge of the underlying mechanism(s) responsible for driving the maintenance of SCI-NP. The leading hypothesis in the field supports a major role for spontaneously active injured nociceptors in driving the maintenance of SCI-NP. Recent data from our laboratory provided additional support for this hypothesis and identified the T-type calcium channels as key players in driving the spontaneous activity of SCI-nociceptors, thus providing a rational pharmacological target to treat SCI-NP. To test whether T-type calcium channels contribute to the maintenance of SCI-NP, male and female SCI and sham rats were treated with TTA-P2 (a blocker of T-type calcium channels) to determine its effects on mechanical hypersensitivity (as measured with the von Frey filaments) and spontaneous ongoing pain (as measured with the conditioned place preference paradigm), and compared them to the effects of gabapentin, a blocker of high voltage-activated calcium channels. We found that both TTA-P2 and gabapentin reduced mechanical hypersensitivity in male and females SCI rats, but surprisingly only TTA-P2 reduced spontaneous ongoing pain in male SCI rats. PERSPECTIVES: SCI-induced neuropathic pain, and in particular the spontaneous ongoing pain component, is notoriously very difficult to treat. Our data provide evidence that inhibition of T-type calcium channels reduces spontaneous ongoing pain in SCI rats, supporting a clinically relevant role for T-type channels in the maintenance of SCI-induced neuropathic pain.
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Affiliation(s)
- Huilin Liu
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Justas Lauzadis
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Kavindu Gunaratna
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Erin Sipple
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Martin Kaczocha
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York
| | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook Pain and Analgesia Research Center (SPARC), Health Sciences Center L4-072, Stony Brook Renaissance School of Medicine, Stony Brook, New York.
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Segmental Upregulation of ASIC1 Channels in the Formalin Acute Pain Mouse Model. Pharmaceuticals (Basel) 2022; 15:ph15121539. [PMID: 36558990 PMCID: PMC9784454 DOI: 10.3390/ph15121539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/23/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Hindpaw injection of formalin in rodents is used to assess acute persistent pain. The response to formalin is biphasic. The initial response (first minutes) is thought to be linked to inflammatory, peripheral mechanisms, while the latter (around 30 min after the injection), is linked to central mechanisms. This model is useful to analyze the effect of drugs at one or both phases, and the involvement of ion channels in the response. Acid-sensing ion channels (ASICs) regulate synaptic activities and play important roles in pain conditions. Recently, psalmotoxin-1 (Pctx-1), a toxin that inhibits ASIC1a-constituted channels, and antisense ASIC1a-RNA, intrathecal administered in mice were shown to affect both phases of the test. METHODS The mouse formalin test was performed on C57/BL6 7- to 9-week-old mice. Behavioral tests were conducted and tissue was extracted to detect proteins (ASIC1 and pERK) and ASIC1-mRNA and mir485-5p levels. RESULTS The injection of formalin was accompanied by an increase in ASIC1 levels. This was detected at the contralateral anterior cingulate cortex (ACC) compared to the ipsilateral side, and both sides of the ACC of vehicle-injected animals. At the spinal cord and dorsal root ganglia, ASIC1 levels followed a gradient stronger at lumbar (L) 3 and decreased towards L5. Gender differences were detected at the ACC; with female mice showing higher ASIC1a levels at the ACC. No significant changes in ASIC1-mRNA levels were detected. Evidence suggests ASIC1 upregulation depends on regulatory microRNAs. CONCLUSION This work highlights the important role of ASIC1 in pain and the potential role of pharmacological therapies aimed at this channel.
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Harding EK, Zamponi GW. Central and peripheral contributions of T-type calcium channels in pain. Mol Brain 2022; 15:39. [PMID: 35501819 PMCID: PMC9063214 DOI: 10.1186/s13041-022-00923-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/13/2022] [Indexed: 02/06/2023] Open
Abstract
AbstractChronic pain is a severely debilitating condition that reflects a long-term sensitization of signal transduction in the afferent pain pathway. Among the key players in this pathway are T-type calcium channels, in particular the Cav3.2 isoform. Because of their biophysical characteristics, these channels are ideally suited towards regulating neuronal excitability. Recent evidence suggests that T-type channels contribute to excitability of neurons all along the ascending and descending pain pathways, within primary afferent neurons, spinal dorsal horn neurons, and within pain-processing neurons in the midbrain and cortex. Here we review the contribution of T-type channels to neuronal excitability and function in each of these neuronal populations and how they are dysregulated in chronic pain conditions. Finally, we discuss their molecular pharmacology and the potential role of these channels as therapeutic targets for chronic pain.
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Synthesis and Pharmacological Evaluation of Novel Selenoethers Glycerol Derivatives for the Treatment of Pain and Inflammation: Involvement of Nitrergic and Glutamatergic Systems. Appl Biochem Biotechnol 2018; 187:1398-1423. [DOI: 10.1007/s12010-018-2887-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 09/10/2018] [Indexed: 12/12/2022]
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Lee JYP, Saez NJ, Cristofori-Armstrong B, Anangi R, King GF, Smith MT, Rash LD. Inhibition of acid-sensing ion channels by diminazene and APETx2 evoke partial and highly variable antihyperalgesia in a rat model of inflammatory pain. Br J Pharmacol 2018; 175:2204-2218. [PMID: 29134638 DOI: 10.1111/bph.14089] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 10/22/2017] [Accepted: 10/31/2017] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Acid-sensing ion channels (ASICs) are primary acid sensors in mammals, with the ASIC1b and ASIC3 subtypes being involved in peripheral nociception. The antiprotozoal drug diminazene is a moderately potent ASIC inhibitor, but its analgesic activity has not been assessed. EXPERIMENTAL APPROACH We determined the ASIC subtype selectivity of diminazene and the mechanism by which it inhibits ASICs using voltage-clamp electrophysiology of Xenopus oocytes expressing ASICs 1-3. Its peripheral analgesic activity was then assessed relative to APETx2, an ASIC3 inhibitor, and morphine, in a Freund's complete adjuvant (FCA)-induced rat model of inflammatory pain. KEY RESULTS Diminazene inhibited homomeric rat ASICs with IC50 values of ~200-800 nM, via an open channel and subtype-dependent mechanism. In rats with FCA-induced inflammatory pain in one hindpaw, diminazene and APETx2 evoked more potent peripheral antihyperalgesia than morphine, but the effect was partial for APETx2. APETx2 potentiated rat ASIC1b at concentrations 30-fold to 100-fold higher than the concentration inhibiting ASIC3, which may have implications for its use in in vivo experiments. CONCLUSIONS AND IMPLICATIONS Diminazene and APETx2 are moderately potent ASIC inhibitors, both inducing peripheral antihyperalgesia in a rat model of chronic inflammatory pain. APETx2 has a more complex ASIC pharmacology, which must be considered when it is used as a supposedly selective ASIC3 inhibitor in vivo. Our use of outbred rats revealed responders and non-responders when ASIC inhibition was used to alleviate inflammatory pain, which is aligned with the concept of number-needed-to-treat in human clinical studies. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
- Jia Yu Peppermint Lee
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Natalie J Saez
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | | | - Raveendra Anangi
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Maree T Smith
- UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia.,School of Pharmacy, The University of Queensland, St Lucia, QLD, Australia
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia.,School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
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Schwarz MG, Namer B, Reeh PW, Fischer MJM. TRPA1 and TRPV1 Antagonists Do Not Inhibit Human Acidosis-Induced Pain. THE JOURNAL OF PAIN 2017; 18:526-534. [PMID: 28062311 DOI: 10.1016/j.jpain.2016.12.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/21/2016] [Accepted: 12/21/2016] [Indexed: 12/31/2022]
Abstract
Acidosis occurs in a variety of pathophysiological and painful conditions where it is thought to excite or contribute to excitation of nociceptive neurons. Despite potential clinical relevance the principal receptor for sensing acidosis is unclear, but several receptors have been proposed. We investigated the contribution of the acid-sensing ion channels, transient receptor potential vanilloid type 1 (TRPV1) and transient receptor potential ankyrin type 1 (TRPA1) to peripheral pain signaling. We first established a human pain model using intraepidermal injection of the TRPA1 agonist carvacrol. This resulted in concentration-dependent pain sensations, which were reduced by experimental TRPA1 antagonist A-967079. Capsaicin-induced pain was reduced by the TRPV1 inhibitor BCTC. Amiloride was used to block acid-sensing ion channels. Testing these antagonists in a double-blind and randomized experiment, we probed the contribution of the respective channels to experimental acidosis-induced pain in 15 healthy human subjects. A continuous intraepidermal injection of pH 4.3 was used to counter the buffering capacity of tissue and generate a prolonged painful stimulation. In this model, addition of A-967079, BCTC or amiloride did not reduce the reported pain. In conclusion, target-validated antagonists, applied locally in human skin, have excluded the main hypothesized targets and the mechanism of the human acidosis-induced pain remains unclear. PERSPECTIVE An acidic milieu is a trigger of pain in many clinical conditions. The aim of this study was to identify the contribution of the currently hypothesized sensors of acid-induced pain in humans. Surprisingly, inhibition of these receptors did not alter acidosis-induced pain.
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Affiliation(s)
- Matthias G Schwarz
- Institute of Physiology and Pathophysiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Namer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Peter W Reeh
- Institute of Physiology and Pathophysiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Michael J M Fischer
- Institute of Physiology and Pathophysiology, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany; Center of Physiology and Pharmacology Medical University of Vienna, Vienna, Austria.
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Abdelhamid RE, Sluka KA. ASICs Mediate Pain and Inflammation in Musculoskeletal Diseases. Physiology (Bethesda) 2016; 30:449-59. [PMID: 26525344 DOI: 10.1152/physiol.00030.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Chronic musculoskeletal pain is debilitating and affects ∼ 20% of adults. Tissue acidosis is present in painful musculoskeletal diseases like rheumatoid arthritis. ASICs are located on skeletal muscle and joint nociceptors as well as on nonneuronal cells in the muscles and joints, where they mediate nociception. This review discusses the properties of different types of ASICs, factors affecting their pH sensitivity, and their role in musculoskeletal hyperalgesia and inflammation.
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Affiliation(s)
- Ramy E Abdelhamid
- Department of Physical Therapy and Rehabilitation Science, Neuroscience Graduate Program, Pain Research Program, University of Iowa, Iowa City, Iowa
| | - Kathleen A Sluka
- Department of Physical Therapy and Rehabilitation Science, Neuroscience Graduate Program, Pain Research Program, University of Iowa, Iowa City, Iowa
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Munkholm TK, Arendt-Nielsen L. The interaction between NGF-induced hyperalgesia and acid-provoked pain in the infrapatellar fat pad and tibialis anterior muscle of healthy volunteers. Eur J Pain 2016; 21:474-485. [PMID: 27634419 DOI: 10.1002/ejp.941] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2016] [Indexed: 11/08/2022]
Abstract
BACKGROUND Tissue pH is lowered in inflamed tissues, and the increased proton concentration activates acid-sensing ion channels (ASICs), contributing to pain and hyperalgesia. ASICs can be upregulated by nerve growth factor (NGF). The aim of this study was to investigate two new human experimental pain models combining NGF- and acid-induced pain in a randomized, controlled, double-blind study. METHODS In experiment 1, volunteers (N = 16) received an injection of either NGF or isotonic saline in each infrapatellar fat pad (IFP). One day after 5 mL of phosphate-buffered acidic saline was infused into each IFP at a rate of 20 mL/h. In experiment 2, the tibialis anterior (TA) muscle of additional volunteers (N = 16) was examined, following the same procedure except that the volume and infusion rate of acid were different (10 mL, 30 mL/h). Continuous pain ratings were recorded during and after acid infusions. In addition, soreness scores on a Likert scale and pressure pain thresholds (PPTs) were assessed. RESULTS The PPT of the IFP was significantly decreased at the NGF injection site on day 1, but acid-provoked pain ratings and the change in PPT from pre- to postinfusion between the knees were similar. In the muscle pain model, local mechanical hyperalgesia developed 3 h after the NGF injection and a significant additional decrease in PPT was found after acid infusion compared to preinfusion. CONCLUSIONS NGF sensitization in the IFP was not facilitated by acid, whereas an acid-provoked enhancement of muscle hyperalgesia was found. NGF sensitization of adipose tissue responds differently to acid provocation compared to muscle tissue. SIGNIFICANCE Quantification of two novel pain models combining NGF and acid. Hyperalgesia developed after NGF injection in the infrapatellar fat pad, but it was not facilitated by acid provocation. Contrary, NGF-induced hyperalgesia in muscle tissue was enhanced by acid.
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Affiliation(s)
- T K Munkholm
- Center for Sensory-Motor Interaction (SMI), Aalborg University, Denmark
| | - L Arendt-Nielsen
- Center for Sensory-Motor Interaction (SMI), Aalborg University, Denmark
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Spinal antinociceptive action of amiloride and its interaction with tizanidine in the rat formalin test. Pain Res Manag 2015; 20:321-6. [PMID: 26357686 PMCID: PMC4676503 DOI: 10.1155/2015/902914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Amiloride has been reported to produce a wide variety of actions, thereby affecting several ionic channels and a multitude of receptors and enzymes. Intrathecal α2-adrenergic receptor agonists produce pronounced analgesia, and amiloride modulates α2-adrenergic receptor agonist binding and function, acting via the allosteric site on the α2A-adrenergic receptor. OBJECTIVES To investigate the antinociceptive interaction of intrathecal amiloride and the α2-adrenoceptor agonist tizanidine using a rat formalin test. METHODS Sprague-Dawley rats were chronically implanted with lumbar intrathecal catheters and were tested for paw flinching using formalin injection. Biphasic painful behaviour was recorded. Amiloride, tizanidine or an amiloride-tizanidine mixture was administered 10 min before formalin injection. To characterize any interactions, isobolographic analysis was performed. The effects of a pretreatment using intrathecally administered yohimbine was also tested. RESULTS Intrathecally administered amiloride (12.5 μg to 100 μg) and tizanidine (0.5 μg to 5 μg), given separately, produced a significant dose-related suppression of the biphasic responses in the formalin test. Isobolographic analysis revealed that the combination of intrathecal amiloride and tizanidine synergistically reduced phase I and II activities. Intrathecally administered yohimbine antagonized or attenuated the antinociceptive effect of amiloride, tizanidine and the amiloride-tizanidine mixture. Intrathecally administered amiloride synergistically interacts with tizanidine to reduce the nociceptive response in the formalin test, most likely by activating α2-adrenoceptors in the spinal cord. CONCLUSIONS Although intrathecal tizanidine produced pronounced analgesia, antinociceptive doses of intrathecal tizanidine also produced several side effects, including bradycardia and sedation. Amiloride produced antinociceptive action against the thermal nociceptive test without side effects in rats.
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Martínez-Rojas VA, Barragán-Iglesias P, Rocha-González HI, Murbartián J, Granados-Soto V. Role of TRPV1 and ASIC3 in formalin-induced secondary allodynia and hyperalgesia. Pharmacol Rep 2014; 66:964-71. [PMID: 25443722 DOI: 10.1016/j.pharep.2014.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 04/02/2014] [Accepted: 06/05/2014] [Indexed: 01/18/2023]
Abstract
BACKGROUND In the present study we determined the role of transient receptor potential V1 channel (TRPV1) and acid-sensing ion channel 3 (ASIC3) in chronic nociception. METHODS 1% formalin was used to produce long-lasting secondary allodynia and hyperalgesia in rats. Western blot was used to determine TRPV1 and ASIC3 expression in dorsal root ganglia. RESULTS Peripheral ipsilateral, but not contralateral, pre-treatment (-10min) with the TRPV1 receptor antagonists capsazepine (0.03-0.3μM/paw) and A-784168 (0.01-1μM/paw) prevented 1% formalin-induced secondary mechanical allodynia and hyperalgesia in the ipsilateral and contralateral paws. Likewise, peripheral ipsilateral, but not contralateral, pre-treatment with the non-selective and selective ASIC3 blocker benzamil (0.1-10μM/paw) and APETx2 (0.02-2μM/paw), respectively, prevented 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. Peripheral ipsilateral post-treatment (day 6 after formalin injection) with capsazepine (0.03-0.3μM/paw) and A-784168 (0.01-1μM/paw) reversed 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. In addition, peripheral ipsilateral post-treatment with benzamil (0.1-10μM/paw) and APETx2 (0.02-2μM/paw), respectively, reversed 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. TRPV1 and ASIC3 proteins were expressed in dorsal root ganglion in normal conditions, and 1% formalin injection increased expression of both proteins in this location at 1 and 6 days compared to naive rats. CONCLUSIONS Data suggest that TRPV1 and ASIC3 participate in the development and maintenance of long-lasting secondary allodynia and hyperalgesia induced by formalin in rats. The use of TRPV1 and ASIC3 antagonists by peripheral administration could prove useful to treat chronic pain.
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Affiliation(s)
- Vladimir A Martínez-Rojas
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur., México, D.F., Mexico
| | - Paulino Barragán-Iglesias
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur., México, D.F., Mexico
| | - Héctor I Rocha-González
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México, D.F., Mexico
| | - Janet Murbartián
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur., México, D.F., Mexico
| | - Vinicio Granados-Soto
- Neurobiology of Pain Laboratory, Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados (Cinvestav), Sede Sur., México, D.F., Mexico.
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Role of NHE1 in Nociception. PAIN RESEARCH AND TREATMENT 2013; 2013:217864. [PMID: 23431433 PMCID: PMC3572692 DOI: 10.1155/2013/217864] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 01/02/2013] [Indexed: 12/14/2022]
Abstract
Intracellular pH is a fundamental parameter to cell function that requires tight homeostasis. In the absence of any regulation, excessive acidification of the cytosol would have the tendency to produce cellular damage. Mammalian Na(+)/H(+) exchangers (NHEs) are electroneutral Na(+)-dependent proteins that exchange extracellular Na(+) for intracellular H(+). To date, there are 9 identified NHE isoforms where NHE1 is the most ubiquitous member, known as the housekeeping exchanger. NHE1 seems to have a protective role in the ischemia-reperfusion injury and other inflammatory diseases. In nociception, NHE1 is found in neurons along nociceptive pathways, and its pharmacological inhibition increases nociceptive behavior in acute pain models at peripheral and central levels. Electrophysiological studies also show that NHE modulates electrical activity of primary nociceptive terminals. However, its role in neuropathic pain still remains controversial. In humans, NHE1 may be responsible for inflammatory bowel diseases since its expression is reduced in Crohn's disease and ulcerative colitis. The purpose of this work is to provide a review of the evidence about participation of NHE1 in the nociceptive processing.
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He QL, Chen Y, Qin J, Mo SL, Wei M, Zhang JJ, Li MN, Zou XN, Zhou SF, Chen XW, Sun LB. Osthole, a herbal compound, alleviates nucleus pulposus-evoked nociceptive responses through the suppression of overexpression of acid-sensing ion channel 3 (ASIC3) in rat dorsal root ganglion. Med Sci Monit 2012; 18:BR229-36. [PMID: 22648244 PMCID: PMC3560735 DOI: 10.12659/msm.882899] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Osthole (Ost), a natural coumarin derivative, has been shown to inhibit many pro-inflammatory mediators and block voltage-gated Na+ channels. During inflammation, acidosis is an important pain inducer which activates nociceptors by gating depolarizing cationic channels, such as acid-sensing ion channel 3 (ASIC3). The aim of this study was to examine the effects of Ost on nucleus pulposus-evoked nociceptive responses and ASIC3 over-expression in the rat dorsal root ganglion, and to investigate the possible mechanism. MATERIAL/METHODS Radicular pain was generated with application of nucleus pulposus (NP) to nerve root. Mechanical allodynia was evaluated using von Frey filaments with logarithmically incremental rigidity to calculate the 50% probability thresholds for mechanical paw withdrawal. ASIC3 protein expression in dorsal root ganglions (DRGs) was assessed with Western blot and immunohistochemistry. Membrane potential (MP) shift of DRG neurons induced by ASIC3-sensitive acid (pH6.5) was determined by DiBAC(4) (3) fluorescence intensity (F.I.). RESULTS The NP-evoked mechanical hyperalgesia model showed allodynia for 3 weeks, and ASIC3 expression was up-regulated in DRG neurons, reaching peak on Day 7. Epidural administration of Ost induced a remarkable and prolonged antinociceptive effect, accompanied by an inhibition of over-expressed ASIC3 protein and of abnormal shift of MP. Amiloride (Ami), an antagonist of ASIC3, strengthened the antinociceptive effect of Ost. CONCLUSIONS Up-regulation of ASIC3 expression may be associated with NP-evoked mechanical hyperalgesia. A single epidural injection of Ost decreased ASIC3 expression in DGR neurons and the pain in the NP-evoked mechanical hyperalgesia model. Osthole may be of great benefit for preventing chronic pain status often seen in lumbar disc herniation (LDH).
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Affiliation(s)
- Qiu-Lan He
- Department of Anesthesiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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Blockade of peripheral and spinal Na+/H+ exchanger increases formalin-induced long-lasting mechanical allodynia and hyperalgesia in rats. Brain Res 2012; 1475:19-30. [DOI: 10.1016/j.brainres.2012.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/31/2012] [Accepted: 08/01/2012] [Indexed: 12/14/2022]
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Abstract
The epithelial Na(+) channel (ENaC) and acid-sensitive ion channel (ASIC) branches of the ENaC/degenerin superfamily of cation channels have drawn increasing attention as potential therapeutic targets in a variety of diseases and conditions. Originally thought to be solely expressed in fluid absorptive epithelia and in neurons, it has become apparent that members of this family exhibit nearly ubiquitous expression. Therapeutic opportunities range from hypertension, due to the role of ENaC in maintaining whole body salt and water homeostasis, to anxiety disorders and pain associated with ASIC activity. As a physiologist intrigued by the fundamental mechanics of salt and water transport, it was natural that Dale Benos, to whom this series of reviews is dedicated, should have been at the forefront of research into the amiloride-sensitive sodium channel. The cloning of ENaC and subsequently the ASIC channels has revealed a far wider role for this channel family than was previously imagined. In this review, we will discuss the known and potential roles of ENaC and ASIC subunits in the wide variety of pathologies in which these channels have been implicated. Some of these, such as the role of ENaC in Liddle's syndrome are well established, others less so; however, all are related in that the fundamental defect is due to inappropriate channel activity.
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Affiliation(s)
- Yawar J Qadri
- Department of Physiology and Biophysics, University of Alabama at Birmingham, AL 35294, USA
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Ouyang H, Bai X, Huang W, Chen D, Dohi S, Zeng W. The antinociceptive activity of intrathecally administered amiloride and its interactions with morphine and clonidine in rats. THE JOURNAL OF PAIN 2011; 13:41-8. [PMID: 22154330 DOI: 10.1016/j.jpain.2011.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/23/2011] [Accepted: 09/27/2011] [Indexed: 10/14/2022]
Abstract
UNLABELLED In this study, we aimed to evaluate the antinociceptive interaction between intrathecally administered amiloride and morphine or clonidine. Using rats chronically implanted with lumbar intrathecal catheters, we examined the ability of intrathecal amiloride, morphine, clonidine, and mixtures of amiloride-morphine and amiloride-clonidine to alter tail-flick latency. To characterize any interactions, isobolographic analysis was performed. The effects of pretreatment with intrathecally administered naloxone or yohimbine were tested. Intrathecal administration of amiloride (25-150 μg), morphine (.25-10 μg), or clonidine (.5-10 μg) alone produced significant dose-dependent antinociception in the tail-flick test. The median effective dose (ED(50)) values for intrathecally administered amiloride, morphine, and clonidine were 120.5 μg, 5.0 μg, and 4.4 μg, respectively. Isobolographic analysis exhibited a synergistic interaction after coadministration of amiloride-morphine and amiloride-clonidine. Intrathecal pretreatment with naloxone (10 μg) completely blocked the antinociceptive effects of morphine and the amiloride-morphine mixture. Intrathecal pretreatment with yohimbine (20 μg) completely blocked the antinociceptive effect of clonidine and antagonized the effect of the amiloride-clonidine mixture. There was no motor dysfunction or significant change in blood pressure or heart rate after the intrathecal administration of amiloride, amiloride-morphine, and amiloride-clonidine. The synergistic effect observed after the coadministration of amiloride and morphine or clonidine suggests a functional interaction among calcium channels, μ-receptors and α(2)-receptors at the spinal cord level of the nociceptive processing system. PERSPECTIVE Although intrathecal morphine and clonidine produces pronounced analgesia, antinociceptive doses of intrathecal morphine and clonidine produce several side effects, including hypotension, bradycardia, sedation, and tolerance. This article presents antinociceptive synergistic interaction between amiloride and morphine, amiloride, and clonidine on thermal nociceptive tests in the rat.
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Affiliation(s)
- Handong Ouyang
- Department of Anesthesiology, State Key Laboratory of Oncology on Southern China, Cancer Center, Sun Yat-Sen University, Guangzhou, China
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Longhi-Balbinot DT, Martins DF, Lanznaster D, Silva MD, Facundo VA, Santos AR. Further analyses of mechanisms underlying the antinociceptive effect of the triterpene 3β, 6β, 16β-trihydroxylup-20(29)-ene in mice. Eur J Pharmacol 2011; 653:32-40. [DOI: 10.1016/j.ejphar.2010.11.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 10/07/2010] [Accepted: 11/26/2010] [Indexed: 10/18/2022]
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Garateix A, Salceda E, Menéndez R, Regalado EL, López O, García T, Morales RA, Laguna A, Thomas OP, Soto E. Antinociception produced by Thalassia testudinum extract BM-21 is mediated by the inhibition of acid sensing ionic channels by the phenolic compound thalassiolin B. Mol Pain 2011; 7:10. [PMID: 21261973 PMCID: PMC3037906 DOI: 10.1186/1744-8069-7-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 01/24/2011] [Indexed: 02/03/2023] Open
Abstract
Background Acid-sensing ion channels (ASICs) have a significant role in the sensation of pain and constitute an important target for the search of new antinociceptive drugs. In this work we studied the antinociceptive properties of the BM-21 extract, obtained from the sea grass Thalassia testudinum, in chemical and thermal models of nociception in mice. The action of the BM-21 extract and the major phenolic component isolated from this extract, a sulphated flavone glycoside named thalassiolin B, was studied in the chemical nociception test and in the ASIC currents of the dorsal root ganglion (DRG) neurons obtained from Wistar rats. Results Behavioral antinociceptive experiments were made on male OF-1 mice. Single oral administration of BM-21 produced a significant inhibition of chemical nociception caused by acetic acid and formalin (specifically during its second phase), and increased the reaction time in the hot plate test. Thalassiolin B reduced the licking behavior during both the phasic and tonic phases in the formalin test. It was also found that BM-21 and thalassiolin B selectively inhibited the fast desensitizing (τ < 400 ms) ASIC currents in DRG neurons obtained from Wistar rats, with a nonsignificant action on ASIC currents with a slow desensitizing time-course. The action of thalassiolin B shows no pH or voltage dependence nor is it modified by steady-state ASIC desensitization or voltage. The high concentration of thalassiolin B in the extract may account for the antinociceptive action of BM-21. Conclusions To our knowledge, this is the first report of an ASIC-current inhibitor derived of a marine-plant extract, and in a phenolic compound. The antinociceptive effects of BM-21 and thalassiolin B may be partially because of this action on the ASICs. That the active components of the extract are able to cross the blood-brain barrier gives them an additional advantage for future uses as tools to study pain mechanisms with a potential therapeutic application.
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Affiliation(s)
- Anoland Garateix
- Centro de Bioproductos Marinos, Agencia de Medio Ambiente, Ministerio de Ciencia, Tecnología y Medio Ambiente, Loma y 37, Alturas del Vedado, CP 10600 La Habana, Cuba
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Tzabazis AZ, Niv SH, Manering NA, Klyukinov M, Cuellar JM, Bhatnagar A, Yeomans DC. Trigeminal antihyperalgesic effect of intranasal carbon dioxide. Life Sci 2010; 87:36-41. [PMID: 20561904 DOI: 10.1016/j.lfs.2010.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2010] [Revised: 04/28/2010] [Accepted: 05/13/2010] [Indexed: 10/19/2022]
Abstract
AIMS Clinical studies demonstrate attenuation of trigeminal-related pain states such as migraine by intranasal CO(2) application. This study investigated the underlying mechanisms of this observation and its potential use to reverse trigeminal pain and hypersensitivity. MAIN METHODS We used a behavioral rat model of capsaicin-induced trigeminal thermal hyperalgesia, intranasal CO2 application and several pharmacologic agents such as carbonic anhydrase, acid-sensing ion channels (ASICs), and TRPV1 blocker as well as acidic buffer solutions to investigate and mimic the underlying mechanism. KEY FINDINGS Intranasal CO(2) application produced a robust dose-dependent antihyperalgesic effect in rats that lasted at least one hour. Blockade of nasal carbonic anhydrase with a dorzolamide solution (Trusopt ophthalmic solution) showed only a non-significant decrease of the antihyperalgesic effect of intranasal CO(2) application. Pharmacologic blockade of ASICs or TRPV(1) receptor significantly attenuated the antihyperalgesic effect of CO(2) application. The effect of intranasal CO(2) application could be mimicked by application of pH 4, but not pH 5, buffer solution to the nasal mucosa. As with CO(2) application, the antihyperalgesic effect of intranasal pH 4 buffer was blocked by nasal application of antagonists to ASICs and TRPV(1) receptors. SIGNIFICANCE Our results indicate that intranasal CO(2) application results in a subsequent attenuation of trigeminal nociception, mediated by protonic activation of TRPV(1) and ASIC channels. A potential central mechanism for this attenuation is discussed. The antihyperalgesic effects of intranasal CO(2) application might be useful for the treatment of trigeminal pain states.
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Affiliation(s)
- Alexander Z Tzabazis
- Department of Anesthesia, Stanford University, 300 Pasteur Drive, Stanford, CA 94305-5117, USA.
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Hori K, Ozaki N, Suzuki S, Sugiura Y. Upregulations of P2X3 and ASIC3 involve in hyperalgesia induced by cisplatin administration in rats. Pain 2010; 149:393-405. [DOI: 10.1016/j.pain.2010.03.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 02/03/2010] [Accepted: 03/05/2010] [Indexed: 11/25/2022]
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Abstract
Neuropathic pain, a severe chronic pain condition characterized by a complex pathophysiology, is a largely unmet medical need. Ion channels, which underlie cell excitability, are heavily implicated in the biological mechanisms that generate and sustain neuropathic pain. This review highlights the biological evidence supporting the involvement of voltage-, proton- and ligand-gated ion channels in the neuropathic pain setting. Ion channel modulators at different research or development stages are reviewed and referenced. Ion channel modulation is one of the main avenues to achieve novel, improved neuropathic pain treatments. Voltage-gated sodium and calcium channel and glutamate receptor modulators are likely to produce new, improved agents in the future. Rationally targeting subtypes of known ion channels, tackling recently discovered ion channel targets or combining drugs with different mechanism of action will be primary sources of new drugs in the longer term.
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Meotti FC, Coelho IDS, Santos ARS. The nociception induced by glutamate in mice is potentiated by protons released into the solution. THE JOURNAL OF PAIN 2010; 11:570-8. [PMID: 20338819 DOI: 10.1016/j.jpain.2009.09.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/19/2009] [Accepted: 09/23/2009] [Indexed: 12/13/2022]
Abstract
UNLABELLED In this study we compare the effect of a glutamate solution with pH adjusted to 7 (3-30 micromol/paw), a non-pH-adjusted glutamate solution (.3-30 micromol/paw, pH range 2.24-1.14), and an acid solution (2% acetic acid, pH 1.4-7) in terms of causing licking behavior in mice. The sum of licking seconds was recorded in the first 15 minutes following the intraplantar (i.pl.) injection of the solutions. Protons potentiated the nociception induced by glutamate. The ED(50) values were 2.5 (1.5-4.2) and 15.1 (11.5-19.9) micromol/paw for the non-pH-adjusted and pH-adjusted glutamate solutions, respectively. The acid solutions at pH 1.4, 2 and 4 induced a similar nociception. The blocking of the acid-sensitive ion channels (ASICs) by amiloride and the antagonism of the transient receptor potential vanilloid subtype-1 (TRPV1) by capsazepine, injected via i.pl., significantly decreased the nociception mediated by acid and by non-pH-adjusted glutamate solutions, but did not affect the nociception caused by the pH-adjusted glutamate solution. The pretreatment with the NMDA-receptor antagonist (MK-801, i.pl.), with the cyclooxygenase inhibitor (indomethacin, i.pl.) or the disruption of the sensorial C fibers by capsaicin, decreased the nociceptive effect of the 3 algogen tested. In summary, the protons present in aqueous solution of glutamate can cause nociception per se or can potentiate the nociception caused by glutamate. These effects are related to the activation of ASICs, TRPV1 and NMDA receptors, inhibition of the synthesis of prostanoids, and disruption of the C fibers. PERSPECTIVE The nociception induced by glutamate is a useful method for investigation of the mechanisms of nociception and the effects of new analgesic drugs. Our findings showed that the protons released from glutamic acid have to be removed from the solution to avoid misinterpretation of results in the search for new analgesic drugs.
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Affiliation(s)
- Flavia Carla Meotti
- Departamento de Ciências Fisiológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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Kuduk SD, Di Marco CN, Bodmer-Narkevitch V, Cook SP, Cato MJ, Jovanovska A, Urban MO, Leitl M, Sain N, Liang A, Spencer RH, Kane SA, Hartman GD, Bilodeau MT. Synthesis, structure-activity relationship, and pharmacological profile of analogs of the ASIC-3 inhibitor A-317567. ACS Chem Neurosci 2010; 1:19-24. [PMID: 22778804 DOI: 10.1021/cn9000186] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 09/29/2009] [Indexed: 11/29/2022] Open
Abstract
The synthesis, structure-activity relationship (SAR), and pharmacological evaluation of analogs of the acid-sensing ion channel (ASIC) inhibitor A-317567 are reported. It was found that the compound with an acetylenic linkage was the most potent ASIC-3 channel blocker. This compound reversed mechanical hypersensitivity in the rat iodoacetate model of osteoarthritis pain, although sedation was noted. Sedation was also observed in ASIC-3 knockout mice, questioning whether sedation and antinociception are mediated via a non-ASIC-3 specific mechanism.
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Walder RY, Rasmussen LA, Rainier JD, Light AR, Wemmie JA, Sluka KA. ASIC1 and ASIC3 play different roles in the development of Hyperalgesia after inflammatory muscle injury. THE JOURNAL OF PAIN 2009; 11:210-8. [PMID: 20015700 DOI: 10.1016/j.jpain.2009.07.004] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 07/01/2009] [Accepted: 07/13/2009] [Indexed: 01/23/2023]
Abstract
UNLABELLED Acid-sensing ion channels (ASICs) respond to acidosis that normally occurs after inflammation. We examined the expression of ASIC1, ASIC2, and ASIC3 mRNAs in lumbar dorsal root ganglion neurons before and 24 hours after carrageenan-induced muscle inflammation. Muscle inflammation causes bilateral increases of ASIC2 and ASIC3 but not ASIC1 (neither ASIC1a nor ASIC1b) mRNA, suggesting differential regulation of ASIC1 versus ASIC2 and ASIC3 mRNA. Similar mRNA increases were observed after inflammation in knockout mice: ASIC2 mRNA increases in ASIC3-/- mice; ASIC2 and ASIC3 mRNAs increase in ASIC1-/- mice. Prior behavioral studies in ASIC3-/- mice showed deficits in secondary hyperalgesia (increased response to noxious stimuli outside the site of injury) but not primary hyperalgesia (increased response to noxious stimuli at the site of injury). In this study, we show that ASIC1-/- mice do not develop primary muscle hyperalgesia but develop secondary paw hyperalgesia. In contrast, and as expected, ASIC3-/- mice develop primary muscle hyperalgesia but do not develop secondary paw hyperalgesia. The pharmacological utility of the nonselective ASIC inhibitor A-317567, given locally, was tested. A-317567 reverses both the primary and the secondary hyperalgesia induced by carrageenan muscle inflammation. Thus, peripherally located ASIC1 and ASIC3 play different roles in the development of hyperalgesia after muscle inflammation. PERSPECTIVE This study shows changes in ASIC mRNA expression and behavioral hyperalgesia of C57Bl/6 (wild type), ASIC1-/-, and ASIC3-/- mice before and after the induction of muscle inflammation. A-317567 was effective in reversing hyperalgesia in these animals, suggesting the potential of ASICs as therapeutic targets for muscle inflammatory pain.
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Affiliation(s)
- Roxanne Y Walder
- Physical Therapy and Rehabilitation Science, Pain Research Program, University of Iowa, Iowa City, Iowa, USA
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ASIC1 and ASIC3 play different roles in the development of Hyperalgesia after inflammatory muscle injury. THE JOURNAL OF PAIN 2009; 146:5-6. [PMID: 20015700 DOI: 10.1016/j.pain.2009.07.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 07/02/2009] [Indexed: 12/11/2022]
Abstract
UNLABELLED Acid-sensing ion channels (ASICs) respond to acidosis that normally occurs after inflammation. We examined the expression of ASIC1, ASIC2, and ASIC3 mRNAs in lumbar dorsal root ganglion neurons before and 24 hours after carrageenan-induced muscle inflammation. Muscle inflammation causes bilateral increases of ASIC2 and ASIC3 but not ASIC1 (neither ASIC1a nor ASIC1b) mRNA, suggesting differential regulation of ASIC1 versus ASIC2 and ASIC3 mRNA. Similar mRNA increases were observed after inflammation in knockout mice: ASIC2 mRNA increases in ASIC3-/- mice; ASIC2 and ASIC3 mRNAs increase in ASIC1-/- mice. Prior behavioral studies in ASIC3-/- mice showed deficits in secondary hyperalgesia (increased response to noxious stimuli outside the site of injury) but not primary hyperalgesia (increased response to noxious stimuli at the site of injury). In this study, we show that ASIC1-/- mice do not develop primary muscle hyperalgesia but develop secondary paw hyperalgesia. In contrast, and as expected, ASIC3-/- mice develop primary muscle hyperalgesia but do not develop secondary paw hyperalgesia. The pharmacological utility of the nonselective ASIC inhibitor A-317567, given locally, was tested. A-317567 reverses both the primary and the secondary hyperalgesia induced by carrageenan muscle inflammation. Thus, peripherally located ASIC1 and ASIC3 play different roles in the development of hyperalgesia after muscle inflammation. PERSPECTIVE This study shows changes in ASIC mRNA expression and behavioral hyperalgesia of C57Bl/6 (wild type), ASIC1-/-, and ASIC3-/- mice before and after the induction of muscle inflammation. A-317567 was effective in reversing hyperalgesia in these animals, suggesting the potential of ASICs as therapeutic targets for muscle inflammatory pain.
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Amidine derived inhibitors of acid-sensing ion channel-3 (ASIC3). Bioorg Med Chem Lett 2009; 19:4059-63. [DOI: 10.1016/j.bmcl.2009.06.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 06/01/2009] [Accepted: 06/03/2009] [Indexed: 02/04/2023]
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Kobayashi H, Yoshiyama M, Zakoji H, Takeda M, Araki I. Sex differences in the expression profile of acid-sensing ion channels in the mouse urinary bladder: a possible involvement in irritative bladder symptoms. BJU Int 2009; 104:1746-51. [PMID: 19493263 DOI: 10.1111/j.1464-410x.2009.08658.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To investigate the expressions and sex differences of acid-sensitive ion channels (i.e. ASIC and transient receptor potential channel V1, TRPV1; both key receptors for extracellular protons that might underlie the acid-evoked pain perception) and other nociceptive ion channels in the mouse bladder. MATERIALS AND METHODS Mucosa and muscle layers of the urinary bladder were separately taken from male and female mice. The gene expressions of ASIC subunits, TRPV1, TRPA1 and TRPM8 were quantified using real-time reverse transcriptase-polymerase chain reaction. The localization of ASIC protein was explored using immunohistochemistry. Continuous-filling cystometry was used to examine the effects of capsazepine, a TRPV1 blocker, on the bladder response to acetic acid. RESULTS ASIC1 was the dominant ASIC subunit expressed in bladder epithelium, whereas both ASIC1 and ASIC2 were expressed in bladder smooth muscle. ASIC3 expression was much less abundant, but localized in the subepithelial region. In the mucosa, the ASIC1 gene was more highly expressed in male than in female mice, whereas the expression level of ASIC2 in the bladder muscle was higher in female than in male mice. The expression of TRPV1 in the bladder showed a sex difference (male < female), but it was much lower than ASIC genes. Furthermore, the intravesical administration of 100 microm capsazepine showed no effect on bladder irritation by acetic acid. TRPA1 and TRPM8 did not show sex differences in their expression. CONCLUSION The expression of ASIC subunit in the bladder was abundant and showed significant sex differences. Thus, ASICs might be involved in the sex difference in the bladder response to acidic irritation.
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Affiliation(s)
- Hideki Kobayashi
- Department of Urology, University of Yamanashi Interdisciplinary Graduate School of Medicine and Engineering, Chuo, Japan
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Identification of the Na+/H+ exchanger 1 in dorsal root ganglion and spinal cord: Its possible role in inflammatory nociception. Neuroscience 2009; 160:156-64. [DOI: 10.1016/j.neuroscience.2009.02.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 02/17/2009] [Accepted: 02/18/2009] [Indexed: 11/24/2022]
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30
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Kuduk SD, Di Marco CN, Chang RK, Dipardo RM, Cook SP, Cato MJ, Jovanovska A, Urban MO, Leitl M, Spencer RH, Kane SA, Bilodeau MT, Hartman GD, Bock MG. Amiloride derived inhibitors of acid-sensing ion channel-3 (ASIC3). Bioorg Med Chem Lett 2009; 19:2514-8. [PMID: 19339181 DOI: 10.1016/j.bmcl.2009.03.029] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 03/10/2009] [Accepted: 03/10/2009] [Indexed: 01/29/2023]
Abstract
A series of amiloride derivatives modified at the 5-position of the pyrazine ring were evaluated as inhibitors of acid-sensing ion channel-3 (ASIC3), a novel target for the treatment of chronic pain.
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Affiliation(s)
- Scott D Kuduk
- Department of Medicinal Chemistry, Merck Research Laboratories, Sumneytown Pike, PO Box 4, West Point, PA 19486, USA
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31
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Rocha-González HI, Herrejon-Abreu EB, López-Santillán FJ, García-López BE, Murbartián J, Granados-Soto V. Acid increases inflammatory pain in rats: effect of local peripheral ASICs inhibitors. Eur J Pharmacol 2008; 603:56-61. [PMID: 19109946 DOI: 10.1016/j.ejphar.2008.12.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Revised: 11/25/2008] [Accepted: 12/09/2008] [Indexed: 02/06/2023]
Abstract
The purpose of this study was to assess the possible antinociceptive effect of the acid sensing ion channels (ASICs) inhibitors amiloride and benzamil after local peripheral administration in three models of inflammatory pain in rats. Reduction of pH, from 7.4 to 5.8 units, significantly increased the flinching/licking behavior induced by either 0.1% serotonin, 0.1% capsaicin or 0.5% formalin. Local peripheral ipsilateral, but not contralateral, injection of amiloride or benzamil significantly reduced nociceptive behaviors (flinching and licking/lifting) induced by serotonin, capsaicin or formalin in acidic conditions (pH 6.2). Interestingly, benzamil produced antinociception at low doses (0.001-0.1 microM/paw) while higher doses (1 microM/paw) did not affect capsaicin- or formalin-induced licking/lifting. Our data suggest that local peripheral inhibition of ASICs play an important role in inflammatory pain.
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Affiliation(s)
- Héctor I Rocha-González
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados, Sede Sur, México, DF, Mexico
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32
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Fujii Y, Ozaki N, Taguchi T, Mizumura K, Furukawa K, Sugiura Y. TRP channels and ASICs mediate mechanical hyperalgesia in models of inflammatory muscle pain and delayed onset muscle soreness. Pain 2008; 140:292-304. [PMID: 18834667 DOI: 10.1016/j.pain.2008.08.013] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 08/19/2008] [Accepted: 08/19/2008] [Indexed: 12/17/2022]
Abstract
The roles of ion channels in sensory neurons were examined in experimental models of muscle pain in the rat. Rats were injected with 50 microl of 4% carrageenan or subjected to an eccentric exercise (ECC) of the gastrocnemius muscle (GM). The Randall-Selitto and von Frey tests were performed on the calves to evaluate mechanical hyperalgesia of the muscle. The changes in expression of four genes and proteins of ion channels in dorsal root ganglia were examined using quantitative PCR and immunohistochemistry, respectively. Effects of antagonists to transient receptor potential (TRP) channels and acid sensing ion channels (ASICs) on the mechanical hyperalgesia induced by carrageenan injection or ECC were evaluated. The mechanical hyperalgesia was observed 6-24h after carrageenan injection and 1-3 days after ECC in the Randall-Selitto test. Infiltrations of the inflammatory cells in the GM were seen in carrageenan-injected animals but not in those subjected to ECC. Expressions of genes and proteins in sensory neurons showed no changes. Intramuscular injection of antagonists to TRPV1 showed an almost complete suppressive effect on ECC-induced muscle hyperalgesia but not a carrageenan-induced one. Antagonists to TRP channels and ASICs showed suppressive effects for both carrageenan- and ECC-induced muscle hyperalgesia. The carrageenan injection and ECC models are useful models of acute inflammatory pain and delayed onset muscle soreness (DOMS), respectively, and the time course and underlying etiology might be different. TRP channels and ASICs are closely related to the development of muscle mechanical hyperalgesia, and TRPV1 is involved in ECC-induced DOMS.
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Affiliation(s)
- Yuko Fujii
- Department of Functional Anatomy and Neuroscience, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan Department of Biochemistry II, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-0065, Japan
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33
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Chanda ML, Mogil JS. Sex differences in the effects of amiloride on formalin test nociception in mice. Am J Physiol Regul Integr Comp Physiol 2006; 291:R335-42. [PMID: 16601256 DOI: 10.1152/ajpregu.00902.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amiloride is a nonspecific blocker of acid-sensing ion channels (ASICs) that have been recently implicated in the mediation of mechanical and chemical/inflammatory nociception. Preliminary data using a transgenic model are suggestive of sex differences in the role of ASICs. We report here that systemic administration of amiloride (10-70 mg/kg ip) produces a robust, dose-dependent blockade of late/tonic phase nociceptive behavior on the mouse formalin test (5%; 20 microl) in female but not male mice, completely abolishing the known sex difference in formalin test response. Adult gonadectomy produced a "switching" of sex differences in amiloride efficacy, with castrated males displaying an amiloride blockade and ovariectomized females rendered less sensitive to amiloride. Gonadectomized mice could be switched back to their intact status using chronic estrogen benzoate or testosterone propionate replacement via osmotic minipump (6 microg/day or 250 microg/day, respectively). It is unclear whether this striking sex difference is due to sex-specific involvement of ASICs in pain processing, but the present data represent one of the first demonstrations of pain-related sex differences with no obvious opioid involvement.
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Affiliation(s)
- Mona Lisa Chanda
- Department of Psychology nd Centre for Research on Pain, McGill University 1205 Dr. Penfield Ave., Montreal, QC H3A 1B1, Canada
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34
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Dubé GR, Lehto SG, Breese NM, Baker SJ, Wang X, Matulenko MA, Honoré P, Stewart AO, Moreland RB, Brioni JD. Electrophysiological and in vivo characterization of A-317567, a novel blocker of acid sensing ion channels. Pain 2006; 117:88-96. [PMID: 16061325 DOI: 10.1016/j.pain.2005.05.021] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 05/05/2005] [Accepted: 05/23/2005] [Indexed: 01/14/2023]
Abstract
Acid Sensing Ion Channels (ASICs) are a group of sodium-selective ion channels that are activated by low extracellular pH. The role of ASIC in disease states remains unclear partly due to the lack of selective pharmacological agents. In this report, we describe the effects of A-317567, a novel non-amiloride blocker, on three distinct types of native ASIC currents evoked in acutely dissociated adult rat dorsal root ganglion (DRG) neurons. A-317567 produced concentration-dependent inhibition of all pH 4.5-evoked ASIC currents with an IC50 ranging between 2 and 30muM, depending upon the type of ASIC current activated. Unlike amiloride, A-317567 equipotently blocked the sustained phase of ASIC3-like current, a biphasic current akin to cloned ASIC3, which is predominant in DRG. When evaluated in the rat Complete Freud's Adjuvant (CFA)-induced inflammatory thermal hyperalgesia model, A-317567 was fully efficacious at a dose 10-fold lower than amiloride. A-317567 was also potent and fully efficacious when tested in the skin incision model of post-operative pain. A-317567 was entirely devoid of any diuresis or natriuresis activity and showed minimal brain penetration. In summary, A-317567 is the first reported small molecule non-amiloride blocker of ASIC that is peripherally active and is more potent than amiloride in vitro and in vivo pain models. The discovery of A-317567 will greatly help to enhance our understanding of the physiological and pathophysiological role of ASICs.
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Affiliation(s)
- G R Dubé
- Abbott Laboratories, Neuroscience Research, Building AP9A-Dept. R4ND,Abbott Park, IL 60064-6118, USA.
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35
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Yudin YK, Tamarova ZA, Ostrovskaya OI, Moroz LL, Krishtal OA. RFa-related peptides are algogenic: evidence in vitro and in vivo. Eur J Neurosci 2004; 20:1419-23. [PMID: 15341614 DOI: 10.1111/j.1460-9568.2004.03607.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RFamide (RFa)-related peptides modulate pain processing in the mammalian CNS. The effects of these peptides are generally considered as 'anti-opioid'. They also decrease the rate of desensitization of acid-sensing ionic channels (ASICs), putative nociceptors in dorsal root ganglia neurons [C. Askwith et al. (2000) Neuron, 26, 133-141]. We have tested the role of mollusc-derived peptide, FMRFa (Phe-Met-Arg-Phe-amide) and its synthetic analogues in peripheral nociception. Here we demonstrate that RFa-related peptides powerfully excite the majority of C-fibres in the skin-nerve preparation of rat: 76% of 55 tested fibres with the conduction velocity below 2 m/s responded with long-lasting discharges to the application of peptides (20 microm). When injected subcutaneously in vivo (mice), they initiate nociceptive behaviour. We confirm the data on humans [S. Ugawa et al. (2002) J. Clin. Invest., 110, 1185-1190]: the activation of C-fibres by acid is inhibited by channel blocker of ASICs, amiloride. However, there is no correlation in the sensitivity of C-fibres to RFa peptides, protons and amiloride: 74% of tested RFa-sensitive C-fibres were insensitive to protons and in 67% of cases the response to peptides was insensitive to amiloride. Thus, powerful excitatory/algogenic action of RFa-related peptides cannot be interpreted solely in terms of their interaction with ASICs. The peptides do not activate any conductance in the somatic membrane of dorsal root ganglion neurons of rats and probably affect still unidentified molecular target(s) responsible for nociceptive signalling.
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Affiliation(s)
- Yevgen K Yudin
- Bogomoletz Institute of Physiology, 01024, Kiev, Ukraine
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36
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Ferreira J, da Silva GL, Calixto JB. Contribution of vanilloid receptors to the overt nociception induced by B2 kinin receptor activation in mice. Br J Pharmacol 2004; 141:787-94. [PMID: 14967737 PMCID: PMC1574249 DOI: 10.1038/sj.bjp.0705546] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The vanilloid receptor (TRPV1) is viewed as a molecular integrator of several nociceptive stimuli. In the present study, we have investigated the role played by TRPV1 in the nociceptive response induced by the peripheral activation of kinin B(2) receptor in mice. 2. The intraplantar (i.pl.) administration of bradykinin (BK) and the selective B(2) agonist Tyr(8)-BK, or the vanilloid agonists resiniferatoxin and capsaicin, into the mouse paw induced a dose-related overt nociception of short duration. The B(2) receptor antagonist Hoe 140 inhibited BK-induced, but not capsaicin-induced, nociceptive response. On the other hand, the TRPV1 antagonist capsazepine inhibited both capsaicin- and BK-mediated nociception. 3. Repeated injections of BK or capsaicin produced desensitization to their nociceptive response. Capsaicin desensitization greatly reduced BK-induced nociception, but in contrast, the desensitization to BK increased the capsaicin response. 4. Administration of low doses of capsaicin or acidified saline did not produce nociception when administered alone, but caused a pronounced effect when administered in association with a subthreshold dose of BK. Moreover, the degeneration of the subset of primary afferent fibers, sensitive to capsaicin, abolished both capsaicin- and BK-induced nociception. 5. The inhibition of phospholipase C (PLC), protein kinase C or phospholipase A(2) markedly decreased the nociception caused by BK, but not that of capsaicin. BK administration increased leukotriene B(4) levels in the injected paw. Likewise, BK-induced overt nociception was decreased by lipoxygenase (LOX) inhibition. 6. These results demonstrate that BK produces overt nociception mediated by TRPV1 receptor stimulation, via PLC pathway activation and LOX product formation.
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Affiliation(s)
- Juliano Ferreira
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina, 88015-420 Florianópolis, SC, Brazil
| | - Gisele L da Silva
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina, 88015-420 Florianópolis, SC, Brazil
| | - João B Calixto
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina, 88015-420 Florianópolis, SC, Brazil
- Author for correspondence:
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Ugawa S, Ueda T, Ishida Y, Nishigaki M, Shibata Y, Shimada S. Amiloride-blockable acid-sensing ion channels are leading acid sensors expressed in human nociceptors. J Clin Invest 2002; 110:1185-90. [PMID: 12393854 PMCID: PMC150796 DOI: 10.1172/jci15709] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Many painful inflammatory and ischemic conditions such as rheumatoid arthritis, cardiac ischemia, and exhausted skeletal muscles are accompanied by local tissue acidosis. In such acidotic states, extracellular protons provoke the pain by opening cation channels in nociceptors. It is generally believed that a vanilloid receptor subtype-1 (VR1) and an acid-sensing ion channel (ASIC) mediate the greater part of acid-induced nociception in mammals. Here we provide evidence for the involvement of both channels in acid-evoked pain in humans and show their relative contributions to the nociception. In our psychophysical experiments, direct infusion of acidic solutions (pH > or = 6.0) into human skin caused localized pain, which was blocked by amiloride, an inhibitor of ASICs, but not by capsazepine, an inhibitor of VR1. Under more severe acidification (pH 5.0) amiloride was less effective in reducing acid-evoked pain. In addition, capsazepine had a partial blocking effect under these conditions. Amiloride itself neither blocked capsaicin-evoked localized pain in human skin nor inhibited proton-induced currents in VR1-expressing Xenopus oocytes. Our results suggest that ASICs are leading acid sensors in human nociceptors and that VR1 participates in the nociception mainly under extremely acidic conditions.
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Affiliation(s)
- Shinya Ugawa
- Department of Anatomy II, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
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38
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Ugawa S, Ueda T, Ishida Y, Nishigaki M, Shibata Y, Shimada S. Amiloride-blockable acid-sensing ion channels are leading acid sensors expressed in human nociceptors. J Clin Invest 2002. [DOI: 10.1172/jci0215709] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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39
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Kellenberger S, Schild L. Epithelial sodium channel/degenerin family of ion channels: a variety of functions for a shared structure. Physiol Rev 2002; 82:735-67. [PMID: 12087134 DOI: 10.1152/physrev.00007.2002] [Citation(s) in RCA: 786] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The recently discovered epithelial sodium channel (ENaC)/degenerin (DEG) gene family encodes sodium channels involved in various cell functions in metazoans. Subfamilies found in invertebrates or mammals are functionally distinct. The degenerins in Caenorhabditis elegans participate in mechanotransduction in neuronal cells, FaNaC in snails is a ligand-gated channel activated by neuropeptides, and the Drosophila subfamily is expressed in gonads and neurons. In mammals, ENaC mediates Na+ transport in epithelia and is essential for sodium homeostasis. The ASIC genes encode proton-gated cation channels in both the central and peripheral nervous system that could be involved in pain transduction. This review summarizes the physiological roles of the different channels belonging to this family, their biophysical and pharmacological characteristics, and the emerging knowledge of their molecular structure. Although functionally different, the ENaC/DEG family members share functional domains that are involved in the control of channel activity and in the formation of the pore. The functional heterogeneity among the members of the ENaC/DEG channel family provides a unique opportunity to address the molecular basis of basic channel functions such as activation by ligands, mechanotransduction, ionic selectivity, or block by pharmacological ligands.
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Affiliation(s)
- Stephan Kellenberger
- Institut de Pharmacologie et de Toxicologie, Université de Lausanne, Lausanne, Switzerland
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40
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Wood JN. Pathobiology of visceral pain: molecular mechanisms and therapeutic implications. II. Genetic approaches to pain therapy. Am J Physiol Gastrointest Liver Physiol 2000; 278:G507-12. [PMID: 10762603 DOI: 10.1152/ajpgi.2000.278.4.g507] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
New analgesic drugs are necessary because a number of pain states are untreatable. Genetic approaches to the identification of analgesic drug targets include mapping genes involved in human pain perception (e.g., trkA involved in hereditary neuropathies), identifying regulators of sensory neuron function in simple multicellular organisms and then investigating the activity of their mammalian homologs (e.g., POU domain transcription factors that specify sensory cell fate), as well as difference, expression, and homology cloning of receptors, ion channels, and transcription factors present in sensory neurons. After target validation through the construction of null mutant mice, high-throughput cell-based screens can be used to identify potential drug candidates. As a result of these approaches, a number of receptors and ion channels present in sensory neurons such as voltage-gated sodium channels [sensory neuron specific (SNS) and Na channel novel] and ATP-gated (P2X3), capsaicin-gated [vanilloid receptor 1(VR1)], and proton-gated [acid-sensing ion channel (ASIC)] channels are now under investigation as potential new analgesic drug targets.
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Affiliation(s)
- J N Wood
- Department of Biology, University College, London WC1E 6BT, United Kingdom.
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