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Khasanov TA, Mineev KS, Kalinovskii AP, Korolkova YV, Palikov VA, Palikova YA, Dyachenko IA, Kozlov SA, Andreev YA, Osmakov DI. Sea anemone Cys-ladder peptide Ms13-1 induces a pain response as a positive modulator of acid-sensing ion channel 1a. FEBS J 2025; 292:2671-2687. [PMID: 39964805 DOI: 10.1111/febs.70032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2024] [Revised: 12/17/2024] [Accepted: 02/10/2025] [Indexed: 02/20/2025]
Abstract
Acid-sensing ion channel 1a (ASIC1a) is involved in processes associated with fear, learning, and neurodegeneration within the central nervous system. However, ASIC1a is also abundant in the peripheral nervous system, where its role is still poorly understood, largely due to the lack of selective ligands. In this study, we present the discovery of the first selective positive allosteric modulator for ASIC1a, isolated from the sea anemone Metridium senile. The active compound, a peptide named Ms13-1, features a novel type of fold named 'Cys-ladder'. Ms13-1 exhibits high affinity and selectivity for ASIC1a, enhancing channel activation in response to a broad range of acidic stimuli (pH 6.9-5.5) without altering the proton affinity for the channel. Moreover, injection of Ms13-1 into the hind paw of mice provokes robust and long-lasting pain-related behavior, which is significantly attenuated by a selective ASIC1 antagonist. The discovery of this novel selective positive allosteric modulator opens up new perspectives to investigate the role of ASIC1a in various physiological processes.
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Affiliation(s)
- Timur A Khasanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Center for Advanced Studies, Russia
| | - Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Aleksandr P Kalinovskii
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Yuliya V Korolkova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Victor A Palikov
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Russia
| | - Yulia A Palikova
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Russia
| | - Igor A Dyachenko
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Russia
| | - Sergey A Kozlov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Yaroslav A Andreev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Dmitry I Osmakov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
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Li Y, Lock A, Fedele L, Zebochin I, Sabate A, Siddle M, Cainarca S, Röderer P, Montag K, Tarroni P, Brüstle O, Shaw T, Taams L, Denk F. Modelling inflammation-induced peripheral sensitization in a dish-more complex than expected? Pain 2025; 166:00006396-990000000-00838. [PMID: 40009350 PMCID: PMC12168811 DOI: 10.1097/j.pain.0000000000003512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Revised: 11/14/2024] [Accepted: 11/15/2024] [Indexed: 02/27/2025]
Abstract
ABSTRACT Peripheral sensitization of nociceptors is believed to be a key driver of chronic pain states. Here, we sought to study the effects of a modified version of inflammatory soup on the excitability of human stem cell-derived sensory neurons. For this, we used a preexisting and a novel stem cell line, modified to stably express the calcium sensor GCamP6f. Upon treatment with inflammatory soup, we observed no changes in neuronal transcription or functional responses upon calcium imaging and only a very minor increase in resting membrane potential (RMP) via whole cell patch clamping: control RMP (-71.31 ± 1.1 mV) vs inflammatory soup RMP (-67.74 ± 1.29 mV), uncorrected 2-tailed independent samples t test, P = 0.0383. Similarly, small changes were observed when treating mouse primary sensory neurons with inflammatory soup. A semi-systematic reexamination of past literature further indicated that observed effects of inflammatory mediators on dissociated sensory neuron cultures are generally small. We conclude that modelling inflammation-induced peripheral sensitization in vitro is nontrivial and will require careful selection of mediators and/or more complex, longitudinal multicellular setups. Especially in the latter, our novel GCamP6f-induced pluripotent stem cell line may be of value.
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Affiliation(s)
- Yuening Li
- Wolfson Sensory, Pain and Regeneration Centre (SPaRC), Guy's Campus, King's College London, London, United Kingdom
- Centre for Inflammation Biology & Cancer Immunology, Department of Inflammation Biology, School of Immunology & Microbial Sciences, King's College London, London, United Kingdom
| | - Amy Lock
- Wolfson Sensory, Pain and Regeneration Centre (SPaRC), Guy's Campus, King's College London, London, United Kingdom
- Centre for Inflammation Biology & Cancer Immunology, Department of Inflammation Biology, School of Immunology & Microbial Sciences, King's College London, London, United Kingdom
| | - Laura Fedele
- Wolfson Sensory, Pain and Regeneration Centre (SPaRC), Guy's Campus, King's College London, London, United Kingdom
| | - Irene Zebochin
- Wolfson Sensory, Pain and Regeneration Centre (SPaRC), Guy's Campus, King's College London, London, United Kingdom
| | - Alba Sabate
- ULB Neuroscience Institute (UNI), Université Libre de Bruxelles (ULB), Gosselies, Belgium
| | - Matthew Siddle
- Institute of Liver Studies, School of Immunology & Microbial Sciences, King's College London, London, United Kingdom
| | | | - Pascal Röderer
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty & University Hospital Bonn, Bonn, Germany
- LIFE&BRAIN GmbH, Cellomics Unit, Bonn, Germany
| | | | | | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty & University Hospital Bonn, Bonn, Germany
- LIFE&BRAIN GmbH, Cellomics Unit, Bonn, Germany
| | - Tanya Shaw
- Centre for Inflammation Biology & Cancer Immunology, Department of Inflammation Biology, School of Immunology & Microbial Sciences, King's College London, London, United Kingdom
| | - Leonie Taams
- Centre for Inflammation Biology & Cancer Immunology, Department of Inflammation Biology, School of Immunology & Microbial Sciences, King's College London, London, United Kingdom
| | - Franziska Denk
- Wolfson Sensory, Pain and Regeneration Centre (SPaRC), Guy's Campus, King's College London, London, United Kingdom
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Peripheral 5-HT3 Receptors Are Involved in the Antinociceptive Effect of Bunodosine 391. Toxins (Basel) 2017; 10:toxins10010012. [PMID: 29280949 PMCID: PMC5793099 DOI: 10.3390/toxins10010012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 12/06/2017] [Accepted: 12/20/2017] [Indexed: 12/27/2022] Open
Abstract
Bunodosine 391 (BDS 391), a low molecular weight compound isolated from the sea anemone Bunodosoma cangicum, increases the nociceptive threshold and inhibits inflammatory hyperalgesia. Serotonin receptors are involved in those effects. In this study, we have expanded the characterization of the antinociceptive effect of BDS 391 demonstrating that, in rats: (a) the compound inhibits (1.2–12 ng/paw) overt pain, in the formalin test, and mechanical hyperalgesia (0.6–6.0 ng/paw) detected in a model of neuropathic pain; (b) intraplantar administration of ondansetron, a selective 5-HT3 receptor antagonist, blocks the effect of BDS 391, whereas ketanserin, a 5-HT2 receptor antagonist, partially reversed this effect, indicating the involvement of peripheral 5-HT2 and 5-HT3 receptors in BDS 391 antinociception; and (c) in binding assay studies, BDS 391 was not able to displace the selective 5-HT receptor antagonists, suggesting that this compound does not directly bind to these receptors. The effect of biguanide, a selective 5-HT3 receptor agonist, was also evaluated. The agonist inhibited the formalin’s nociceptive response, supporting an antinociceptive role for 5-HT3 receptors. Our study is the first one to show that a non-peptidic low molecular weight compound obtained from a sea anemone is able to induce antinociception and that activation of peripheral 5-HT3 receptors contributes to this effect.
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Reilly JM, Dharmalingam B, Marsh SJ, Thompson V, Goebel A, Brown DA. Effects of serum immunoglobulins from patients with complex regional pain syndrome (CRPS) on depolarisation-induced calcium transients in isolated dorsal root ganglion (DRG) neurons. Exp Neurol 2015; 277:96-102. [PMID: 26708558 DOI: 10.1016/j.expneurol.2015.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 12/10/2015] [Accepted: 12/15/2015] [Indexed: 12/28/2022]
Abstract
Complex regional pain syndrome (CRPS) is thought to have an auto-immune component. One such target recently proposed from the effects of auto-immune IgGs on Ca(2+) transients in cardiac myocytes and cell lines is the α1-adrenoceptor. We have tested whether such IgGs exerted comparable effects on nociceptive sensory neurons isolated from rat dorsal root ganglia. Depolarisation-induced [Ca(2+)]i transients were generated by applying 30 mM KCl for 2 min and monitored by Fura-2 fluorescence imaging. No IgGs tested (including 3 from CRPS patients) had any significant effect on these [Ca(2+)]i transients. However, IgG from one CRPS patient consistently and significantly reduced the K(+)-induced response of cells that had been pre-incubated for 24h with a mixture of inflammatory mediators (1 μM histamine, 5-hydroxytryptamine, bradykinin and PGE2). Since this pre-incubation also appeared to induce a comparable inhibitory response to the α1-agonist phenylephrine, this is compatible with the α1-adrenoceptor as a target for CRPS auto-immunity. A mechanism whereby this might enhance pain is suggested.
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Affiliation(s)
- Joanne M Reilly
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Backialakshmi Dharmalingam
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK; Pain Research Institute, Department of Translational Medicine, University of Liverpool, Liverpool, L9 7AL, UK
| | - Stephen J Marsh
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Victoria Thompson
- Pain Research Institute, Department of Translational Medicine, University of Liverpool, Liverpool, L9 7AL, UK
| | - Andreas Goebel
- Pain Research Institute, Department of Translational Medicine, University of Liverpool, Liverpool, L9 7AL, UK.
| | - David A Brown
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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Sun WH, Chen CC. Roles of Proton-Sensing Receptors in the Transition from Acute to Chronic Pain. J Dent Res 2015; 95:135-42. [PMID: 26597969 DOI: 10.1177/0022034515618382] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Chronic pain, when not effectively treated, is a leading health and socioeconomic problem and has a harmful effect on all aspects of health-related quality of life. Therefore, understanding the molecular mechanism of how pain transitions from the acute to chronic phase is essential for developing effective novel analgesics. Accumulated evidence has shown that the transition from acute to chronic pain is determined by a cellular signaling switch called hyperalgesic priming, which occurs in primary nociceptive afferents. The hyperalgesic priming is triggered by inflammatory mediators and is involved in a signal switch from protein kinase A (PKA) to protein kinase Cε (PKCε) located in both isolectin B4 (IB4)-positive (nonpeptidergic) and IB4-negative (peptidergic) nociceptors. Acidosis may be the decisive factor regulating the PKA-to-PKCε signal switch in a proton-sensing G-protein-coupled receptor-dependent manner. Protons can also induce the hyperalgesic priming in IB4-negative muscle nociceptors in a PKCε-independent manner. Acid-sensing ion channel 3 (ASIC3) and transient receptor potential/vanilloid receptor subtype 1 (TRPV1) are 2 major acid sensors involved in the proton-induced hyperalgesic priming. The proton-induced hyperalgesic priming in muscle afferents can be prevented by a substance P-mediated signaling pathway. In this review, we summarize the factors that modulate hyperalgesic priming in both IB4-positive and IB4-negative nociceptors and discuss the role of acid signaling in inflammatory and noninflammatory pain as well as orofacial muscle pain.
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Affiliation(s)
- W H Sun
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - C C Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan Taiwan Mouse Clinic-National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei, Taiwan
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Huang WY, Dai SP, Chang YC, Sun WH. Acidosis Mediates the Switching of Gs-PKA and Gi-PKCε Dependence in Prolonged Hyperalgesia Induced by Inflammation. PLoS One 2015; 10:e0125022. [PMID: 25933021 PMCID: PMC4416776 DOI: 10.1371/journal.pone.0125022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 03/19/2015] [Indexed: 12/27/2022] Open
Abstract
Chronic inflammatory pain, when not effectively treated, is a costly health problem and has a harmful effect on all aspects of health-related quality of life. Previous studies suggested that in male Sprague Dawley rats, prostaglandin E2 (PGE2)-induced short-term hyperalgesia depends on protein kinase A (PKA) activity, whereas long-lasting hyperalgesia induced by PGE2 with carrageenan pre-injection, requires protein kinase Cε (PKCε). However, the mechanism underlying the kinase switch with short- to long-term hyperalgesia remains unclear. In this study, we used the inflammatory agents carrageenan or complete Freund's adjuvant (CFA) to induce long-term hyperalgesia, and examined PKA and PKCε dependence and switching time. Hyperalgesia induced by both agents depended on PKA/PKCε and Gs/Gi-proteins, and the switching time from PKA to PKCε and from Gs to Gi was about 3 to 4 h after inflammation induction. Among the single inflammatory mediators tested, PGE2 and 5-HT induced transient hyperalgesia, which depended on PKA and PKCε, respectively. Only acidic solution-induced hyperalgesia required Gs-PKA and Gi-PKCε, and the switch time for kinase dependency matched inflammatory hyperalgesia, in approximately 2 to 4 h. Thus, acidosis in inflamed tissues may be a decisive factor to regulate switching of PKA and PKCε dependence via proton-sensing G-protein-coupled receptors.
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Affiliation(s)
- Wei-Yu Huang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Shih-Ping Dai
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Yan-Ching Chang
- Department of Life Sciences, National Central University, Jhongli, Taiwan
| | - Wei-Hsin Sun
- Department of Life Sciences, National Central University, Jhongli, Taiwan
- Institute of Systems Biology & Bioinformatics, National Central University, Jhongli, Taiwan
- * E-mail:
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Su YS, Sun WH, Chen CC. Molecular mechanism of inflammatory pain. World J Anesthesiol 2014; 3:71-81. [DOI: 10.5313/wja.v3.i1.71] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 09/20/2013] [Accepted: 11/03/2013] [Indexed: 02/07/2023] Open
Abstract
Chronic inflammatory pain resulting from arthritis, nerve injury and tumor growth is a serious public health issue. One of the major challenges in chronic inflammatory pain research is to develop new pharmacologic treatments with long-term efficacy and few side effects. The mediators released from inflamed sites induce complex changes in peripheral and central processing by directly acting on transducer receptors located on primary sensory neurons to transmit pain signals or indirectly modulating pain signals by activating receptors coupled with G-proteins and second messengers. High local proton concentration (acidosis) is thought to be a decisive factor in inflammatory pain and other mediators such as prostaglandin, bradykinin, and serotonin enhance proton-induced pain. Proton-sensing ion channels [transient receptor potential V1 (TRPV1) and the acid-sensing ion channel (ASIC) family] are major receptors for direct excitation of nociceptive sensory neurons in response to acidosis or inflammation. G-protein-coupled receptors activated by prostaglandin, bradykinin, serotonin, and proton modulate functions of TRPV1, ASICs or other ion channels, thus leading to inflammation- or acidosis-linked hyperalgesia. Although detailed mechanisms remain unsolved, clearly different types of pain or hyperalgesia could be due to complex interactions between a distinct subset of inflammatory mediator receptors expressed in a subset of nociceptors. This review describes new directions for the development of novel therapeutic treatments in pain.
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Serotonin facilitates peripheral pain sensitivity in a manner that depends on the nonproton ligand sensing domain of ASIC3 channel. J Neurosci 2013; 33:4265-79. [PMID: 23467344 DOI: 10.1523/jneurosci.3376-12.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tissue acidosis and inflammatory mediators play critical roles in inflammatory pain. Extracellular acidosis activates acid-sensing ion channels (ASICs), which have emerged as key sensors for extracellular protons in the central and peripheral nervous systems and play key roles in pain sensation and transmission. Additionally, inflammatory mediators, such as serotonin (5-HT), are known to enhance pain sensation. However, functional interactions among protons, inflammatory mediators, and ASICs in pain sensation are poorly understood. In the present study, we show that 5-HT, a classical pro-inflammatory mediator, specifically enhances the proton-evoked sustained, but not transient, currents mediated by homomeric ASIC3 channels and heteromeric ASIC3/1a and ASIC3/1b channels. Unexpectedly, the effect of 5-HT on ASIC3 channels does not involve activation of 5-HT receptors, but is mediated via a functional interaction between 5-HT and ASIC3 channels. We further show that the effect of 5-HT on ASIC3 channels depends on the newly identified nonproton ligand sensing domain. Finally, coapplication of 5-HT and acid significantly increased pain-related behaviors as assayed by the paw-licking test in mice, which was largely attenuated in ASIC3 knock-out mice, and inhibited by the nonselective ASIC inhibitor amiloride. Together, these data identify ASIC3 channels as an unexpected molecular target for acute actions of 5-HT in inflammatory pain sensation and reveal an important role of ASIC3 channels in regulating inflammatory pain via coincident detection of extracellular protons and inflammatory mediators.
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Jung KT, Yoon MH, Lee HY, Yu BY, Kim DK, Lim KJ. Effects of Palonosetron, a 5-HT3 Receptor Antagonist, on Mechanical Allodynia in a Rat Model of Postoperative Pain. Korean J Pain 2013; 26:125-9. [PMID: 23614072 PMCID: PMC3629337 DOI: 10.3344/kjp.2013.26.2.125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 11/07/2022] Open
Abstract
Background 5-hydroxytryptamine 3 (5-HT3) receptors have been known to be associated with the modulation of nociceptive transmission. However, it is uncertain whether 5-HT3 plays a role in the antinociceptive or pronociceptive pathway for incisional pain. In this study, we evaluated the effects of palonosetron, a 5-HT3 receptor antagonist, on incisional pain in rats when administered intrathecally or intraplantarly. Methods An intrathecal catheter was implanted through the cisterna magna and placed in the intrathecal space of rats. An incision in the plantaris muscle of the right hind paw was done under anesthesia with sevoflurane. Withdrawal thresholds were evaluated with the von Frey filament after 2 hours. Palonosetron (0.5 and 0.1 µg intrathecally; 0.5 µg intraplantarly) was administered and the thresholds were observed for 4 hours. Results Mechanical hypersensitivity developed after the incision. Intrathecal palonosetron (0.5 µg and 0.1 µg) did not alter the paw withdrawal threshold. Intraplantar palonosetron (0.5 µg) also did not change the paw withdrawal threshold. Conclusions Intrathecal and intraplantar palonosetron (0.5 µg) had no effect on modulating the mechanical hypersensitivity in the incisional pain model of rats.
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Affiliation(s)
- Ki Tae Jung
- Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, Gwangju, Korea
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Petho G, Reeh PW. Sensory and signaling mechanisms of bradykinin, eicosanoids, platelet-activating factor, and nitric oxide in peripheral nociceptors. Physiol Rev 2013; 92:1699-775. [PMID: 23073630 DOI: 10.1152/physrev.00048.2010] [Citation(s) in RCA: 202] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Peripheral mediators can contribute to the development and maintenance of inflammatory and neuropathic pain and its concomitants (hyperalgesia and allodynia) via two mechanisms. Activation or excitation by these substances of nociceptive nerve endings or fibers implicates generation of action potentials which then travel to the central nervous system and may induce pain sensation. Sensitization of nociceptors refers to their increased responsiveness to either thermal, mechanical, or chemical stimuli that may be translated to corresponding hyperalgesias. This review aims to give an account of the excitatory and sensitizing actions of inflammatory mediators including bradykinin, prostaglandins, thromboxanes, leukotrienes, platelet-activating factor, and nitric oxide on nociceptive primary afferent neurons. Manifestations, receptor molecules, and intracellular signaling mechanisms of the effects of these mediators are discussed in detail. With regard to signaling, most data reported have been obtained from transfected nonneuronal cells and somata of cultured sensory neurons as these structures are more accessible to direct study of sensory and signal transduction. The peripheral processes of sensory neurons, where painful stimuli actually affect the nociceptors in vivo, show marked differences with respect to biophysics, ultrastructure, and equipment with receptors and ion channels compared with cellular models. Therefore, an effort was made to highlight signaling mechanisms for which supporting data from molecular, cellular, and behavioral models are consistent with findings that reflect properties of peripheral nociceptive nerve endings. Identified molecular elements of these signaling pathways may serve as validated targets for development of novel types of analgesic drugs.
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Affiliation(s)
- Gábor Petho
- Pharmacodynamics Unit, Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Pécs, Pécs, Hungary
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Ghorbani ML, Nyborg NCB, Fjalland B, Sheykhzade M. Calcium activity of upper thoracic dorsal root ganglion neurons in zucker diabetic Fatty rats. Int J Endocrinol 2013; 2013:532850. [PMID: 23662103 PMCID: PMC3639628 DOI: 10.1155/2013/532850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 01/23/2023] Open
Abstract
The aim of the present study was to examine the calcium activity of C8-T5 dorsal root ganglion (DRG) neurons from Zucker diabetic fatty rats. In total, 8 diabetic ZDF fatty animals and 8 age-matched control ZDF lean rats were employed in the study. C8-T5 dorsal root ganglia were isolated bilaterally from 14 to 18 weeks old rats, and a primary culture was prepared. Calcium activity was measured ratiometrically using the fluorescent Ca(2+)-indicator Fura-2 acetoxymethyl ester. All neurons were stimulated twice with 20 mM K(+), followed by stimulation with either 0.3 or 0.5 μ M Capsaicin, alone or in combination with algogenic chemicals (bradykinin, serotonin, prostaglandin E2 (all 10(-5) M), and adenosine (10(-3) M)) at pH 7.4 and 6.0. Neurons from diabetic animals exhibited an overall increased response to stimulation with 20 mM K(+) compared to neurons from control. Stimulation with Capsaicin alone caused an augmented response in neurons from diabetic animals compared to control animals. When stimulated with a combination of Capsaicin and algogenic chemicals, no differences between the two groups of neurons were measured, neither at pH 7.4 nor 6.0. In conclusion, diabetes-induced alterations in calcium activity of the DRG neurons were found, potentially indicating altered neuronal responses during myocardial ischemia.
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Affiliation(s)
- Marie Louise Ghorbani
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- *Marie Louise Ghorbani:
| | | | - Bjarne Fjalland
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Majid Sheykhzade
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
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Leak K⁺ channel mRNAs in dorsal root ganglia: relation to inflammation and spontaneous pain behaviour. Mol Cell Neurosci 2012; 49:375-86. [PMID: 22273507 PMCID: PMC3334831 DOI: 10.1016/j.mcn.2012.01.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 01/02/2012] [Accepted: 01/04/2012] [Indexed: 02/05/2023] Open
Abstract
Two pore domain potassium (K2P) channels (KCNKx.x) cause K + leak currents and are major contributors to resting membrane potential. Their roles in dorsal root ganglion (DRG) neurons normally, and in pathological pain models, are poorly understood. Therefore, we examined mRNA levels for 10 K2P channels in L4 and L5 rat DRGs normally, and 1 day and 4 days after unilateral cutaneous inflammation, induced by intradermal complete Freund's adjuvant (CFA) injections. Spontaneous foot lifting (SFL) duration (spontaneous pain behaviour) was measured in 1 day and 4 day rats < 1 h before DRG harvest. mRNA levels for KCNK channels and Kv1.4 relative to GAPDH (n = 4–6 rats/group) were determined with real-time RT-PCR. This study is the first to demonstrate expression of THIK1, THIK2 and TWIK2 mRNA in DRGs. Abundance in normal DRGs was, in descending order:
Kv1.4 > TRESK(KCNK18) > TRAAK(KCNK4) > TREK2(KCNK10) = TWIK2(KCNK6) > TREK1 (KCNK2) = THIK2(KCNK12) > TASK1(KCNK3) > TASK2(KCNK5) > THIK1(KCNK13) = TASK3(KCNK9).
During inflammation, the main differences from normal in DRG mRNA levels were bilateral, suggesting systemic regulation, although some channels showed evidence of ipsilateral modulation. By 1 day, bilateral K2P mRNA levels had decreased (THIK1) or increased (TASK1, THIK2) but by 4 days they were consistently decreased (TASK2, TASK3) or tended to decrease (excluding TRAAK). The decreased TASK2 mRNA was mirrored by decreased protein (TASK2-immunoreactivity) at 4 days. Ipsilateral mRNA levels at 4 days compared with 1 day were lower (TRESK, TASK1, TASK3, TASK2 and THIK2) or higher (THIK1). Ipsilateral SFL duration during inflammation was positively correlated with ipsilateral TASK1 and TASK3 mRNAs, and contralateral TASK1, TRESK and TASK2 mRNAs. Thus changes in K2P mRNA levels occurred during inflammation and for 4 K2P channels were associated with spontaneous pain behaviour (SFL). K2P channels and their altered expression are therefore associated with inflammation-induced pain.
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Characterization of a calcitonin gene-related peptide release assay in rat isolated distal colon. Arch Pharm Res 2010; 32:1775-81. [DOI: 10.1007/s12272-009-2216-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 09/22/2009] [Accepted: 09/25/2009] [Indexed: 10/19/2022]
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15
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Abstract
BACKGROUND The authors have demonstrated a decrease in pH in the incisional wound environment, suggesting a possible contribution of low pH to postsurgical pain. In this study, the authors characterized the acid-responsiveness of nociceptors innervating the plantar aspect of the rat hind paw 1 day after plantar incision and compared this to plantar skin from unincised control rats. METHODS Using the rat glabrous in vitro skin-tibial nerve preparation, afferent nerve activities from single mechanosensitive nociceptors were recorded. Differences in mechanosensitivity, spontaneous activity, and chemosensitivity of units were evaluated. For chemosensitivity, acid-responsiveness of nociceptors to lactic acid (pH 5.5 to 6.5) was studied. RESULTS C-fibers showed dose-dependent, sustained responses to lactic acid. A greater proportion of C-fibers from 2 mm or less from the incision was activated by pH 6.0 lactic acid (52.9%) compared to control (14.3%). Total evoked potentials during acid exposure were greater in C-fibers innervating 2 mm or less from the incision compared to those in unincised skin. The prevalence of acid responses and total evoked potentials during acid exposure in C-fibers innervating more than 2 mm from the incision were not different from control. Few A-fibers responded to lactic acid, with a range of pH 5.5 to 6.5 in both incision and control groups. Increased spontaneous activity and mechanosensitivity were also evident. CONCLUSIONS C-fibers in the vicinity of the incision showed qualitatively and quantitatively greater chemosensitivity to pH 6.0 lactic acid compared to control. This change was localized to 2 mm or less from the incision, suggesting increased chemosensitivity of nociceptive C-fibers 1 day after plantar incision.
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Affiliation(s)
- Sinyoung Kang
- Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA.
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16
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Pethő G, Reeh PW. Effects of Bradykinin on Nociceptors. NEUROGENIC INFLAMMATION IN HEALTH AND DISEASE 2009. [DOI: 10.1016/s1567-7443(08)10407-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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17
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Abstract
Serotonin (5-hydroxtryptamine, 5-HT) is an important molecule in pain processing and modulation. Whether 5-HT has an analgesic or hyperalgesic action depends on the cell type and type of receptor it acts on. In the periphery, 5-HT sensitizes afferent nerve fibers, thus contributing to hyperalgesia in inflammation and nerve injury. In the trigeminal system, agonism at 5-HT1B/D receptors reduces neurotransmitter release, but actions through the 5-HT2A receptor may underlie chronic headache. Furthermore, genetic alterations in the 5-HT system may influence the susceptibility to migraine. In the central nervous system, 5-HT is involved in descending inhibition, but facilitatory serotonergic pathways may be functionally more important.
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Affiliation(s)
- Claudia Sommer
- Department of Neurology, Neurologische Universitätsklinik, Josef-Schneider-Str. 11, D-97080 Würzburg, Germany.
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18
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Zhang Y, Xiang B, Li YM, Wang Y, Wang X, Wang YN, Wu LL, Yu GY. Expression and characteristics of vanilloid receptor 1 in the rabbit submandibular gland. Biochem Biophys Res Commun 2006; 345:467-73. [PMID: 16684507 DOI: 10.1016/j.bbrc.2006.04.106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 04/17/2006] [Indexed: 11/24/2022]
Abstract
Vanilloid receptor 1 (VR1) is a polymodal receptor originally found in sensory neurons of the central nervous system. Recent evidence indicates that VR1 is also expressed in non-neuronal tissues. We report here endogenous expression of VR1 in rabbit submandibular gland (SMG) and its possible role in regulating saliva secretion based on: (i) the expression of VR1 mRNA and protein detected in SMG; (ii) VR1 was mainly localized in the basolateral membrane of duct cells and the cytoplasm of acinar cells and also in cytoplasm of primary cultured neonatal rabbit SMG cells; (iii) stimulation of neonatal rabbit SMG cells with capsaicin induced a significant increase in intracellular calcium, and capsazepine, a VR1 antagonist, abolished this increase; (iv) infusion of capsaicin via the external carotid artery to isolated SMG increased saliva secretion of the gland. These findings indicated that VR1 was expressed in SMG and appeared to play an important role in regulating saliva secretion.
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Affiliation(s)
- Yan Zhang
- Department of Physiology and Pathophysiology, Key Laboratory of Molecular Cardiovascular Sciences, Peking University Health Science Center, Beijing, China
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19
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Alessandri-Haber N, Dina OA, Joseph EK, Reichling D, Levine JD. A transient receptor potential vanilloid 4-dependent mechanism of hyperalgesia is engaged by concerted action of inflammatory mediators. J Neurosci 2006; 26:3864-74. [PMID: 16597741 PMCID: PMC6674137 DOI: 10.1523/jneurosci.5385-05.2006] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The transient receptor potential vanilloid 4 (TRPV4) is a primary afferent transducer that plays a crucial role in neuropathic hyperalgesia for osmotic and mechanical stimuli, as well as in inflammatory mediator-induced hyperalgesia for osmotic stimuli. In view of the clinical importance of mechanical hyperalgesia in inflammatory states, the present study investigated the role of TRPV4 in mechanical hyperalgesia induced by inflammatory mediators and the second-messenger pathways involved. Intradermal injection of either the inflammogen carrageenan or a soup of inflammatory mediators enhanced the nocifensive paw-withdrawal reflex elicited by hypotonic or mechanical stimuli in rat. Spinal administration of TRPV4 antisense oligodeoxynucleotide blocked the enhancement without altering baseline nociceptive threshold. Similarly, in TRPV4(-/-) knock-out mice, inflammatory soup failed to induce any significant mechanical or osmotic hyperalgesia. In vitro investigation showed that inflammatory mediators engage the TRPV4-mediated mechanism of sensitization by direct action on dissociated primary afferent neurons. Additional behavioral observations suggested that multiple mediators are necessary to achieve sufficient activation of the cAMP pathway to engage the TRPV4-dependent mechanism of hyperalgesia. In addition, direct activation of protein kinase A or protein kinase C epsilon, two pathways that mediate inflammation-induced mechanical hyperalgesia, also induced hyperalgesia for both hypotonic and mechanical stimuli that was decreased by TRPV4 antisense and absent in TRPV4(-/-) mice. We conclude that TRPV4 plays a crucial role in the mechanical hyperalgesia that is generated by the concerted action of inflammatory mediators present in inflamed tissues.
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Affiliation(s)
- Nicole Alessandri-Haber
- Division of Neurosciences, Department of Oral and Maxillofacial Surgery, University of California, San Francisco, California 94143-0440, USA.
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20
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Ma C, Greenquist KW, Lamotte RH. Inflammatory Mediators Enhance the Excitability of Chronically Compressed Dorsal Root Ganglion Neurons. J Neurophysiol 2006; 95:2098-107. [PMID: 16381809 DOI: 10.1152/jn.00748.2005] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A laterally herniated disk, spinal stenosis, and various degenerative or traumatic diseases of the spine can sometimes lead to a chronic compression and inflammation of the dorsal root ganglion and chronic abnormal sensations including pain. After a chronic compression of the dorsal root ganglion (CCD) in rats, the somata in the dorsal root ganglion (DRG) become hyperexcitable, and some exhibit ectopic, spontaneous activity (SA). Inflammatory mediators have a potential role in modulating the excitability of DRG neurons and therefore may contribute to the neuronal hyperexcitability after CCD. In this study, an inflammatory soup (IS) consisting of bradykinin, serotonin, prostaglandin E2, and histamine (each 10−6M) was applied topically to the DRG. The responses of DRG neurons were electrophysiologically recorded extracellularly from teased dorsal root fibers or intracellularly from the somata in the intact DRG or from dissociated neurons within 30 h of culture. In all three preparations, IS remarkably increased the discharge rates of SA CCD neurons and evoked discharges in more silent-CCD than control neurons. IS slightly depolarized the resting membrane potential and decreased the current and voltage thresholds of action potential in both intact and dissociated neurons, although the magnitude of depolarization or decrease in action potential threshold was not significantly different between CCD and control. IS-evoked responses were found in a proportion of neurons in each size category including those with and without nociceptive properties. Inflammatory mediators, by increasing the excitability of DRG somata, may contribute to CCD-induced neuronal hyperexcitability and to hyperalgesia and tactile allodynia.
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Affiliation(s)
- C Ma
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510, USA
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21
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Elmes SJR, Millns PJ, Smart D, Kendall DA, Chapman V. Evidence for biological effects of exogenous LPA on rat primary afferent and spinal cord neurons. Brain Res 2006; 1022:205-13. [PMID: 15353230 DOI: 10.1016/j.brainres.2004.07.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2004] [Indexed: 10/26/2022]
Abstract
There is growing behavioural evidence that the phospholipid growth factor lysophosphatidic acid (LPA) modulates nociceptive responses in vivo. The present study investigated further the effects of LPA on peripheral nociceptive processing. Effects of intraplantar injection of LPA on ongoing and peripheral mechanically evoked responses of spinal neurons were studied in vivo. In addition, LPA-evoked responses of adult rat dorsal root ganglion (DRG) neurons were studied with calcium imaging. To determine whether LPA may also act at the level of the spinal cord, LPA receptor G-protein coupling in lumbar spinal cord sections was studied with in vitro autoradiography of guanylyl 5'-[g-[(35)S]thio]triphosphate ([(35)S]GTPgammaS) binding. Intraplantar injection of LPA (5 microg/5 microl) significantly increased the duration (P<0.001) and frequency of spinal neuronal firing (P<0.01), compared to vehicle. Intraplantar injection of LPA (1 microg/5 microl) did not significantly alter innocuous and noxious mechanically evoked responses of spinal neurons, but a higher dose of LPA (5 microg) significantly (P<0.05) attenuated mechanically evoked responses of spinal neurons. Calcium imaging studies demonstrated that LPA (0.001-3 microM) increases intracellular calcium concentration in adult DRG neurons, suggesting that LPA can produce direct effects on. Incubation of spinal cord sections with LPA (1 microM) significantly (P<0.001) increased [(35)S]GTPgammaS binding in the superficial laminae of the dorsal horn of the spinal cord, suggesting that LPA may also have biological effects at this level. These data provide further evidence that exogenous LPA can modulate nociceptive processing and suggest that this may be mediated by a direct effect on primary afferent nociceptors.
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Affiliation(s)
- Steven J R Elmes
- Institute of Neuroscience, School of Biomedical Sciences, E Floor, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
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22
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Willis WD. Chapter 3 The Nociceptive Membrane: Historical Overview. CURRENT TOPICS IN MEMBRANES 2006. [DOI: 10.1016/s1063-5823(06)57002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Takumida M, Kubo N, Ohtani M, Suzuka Y, Anniko M. Transient receptor potential channels in the inner ear: presence of transient receptor potential channel subfamily 1 and 4 in the guinea pig inner ear. Acta Otolaryngol 2005; 125:929-34. [PMID: 16193584 DOI: 10.1080/00016480510038572] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
CONCLUSION The results of this study indicate that transient receptor potential subfamily 1 (TRPV1) may play a functional role in sensory cell physiology and that TRPV4 may be important for fluid homeostasis in the inner ear. OBJECTIVE To analyze the expression of TRPV1 and -4 in the normal guinea pig inner ear. MATERIAL AND METHODS Albino guinea pigs were used. The location of TRPV1 and -4 in the inner ear, i.e. cochlea, vestibular end organs and endolymphatic sac, was investigated by means of immunohistochemistry. RESULTS Immunohistochemistry revealed the presence of TRPV1 in the hair cells and supporting cells of the organ of Corti, in spiral ganglion cells, sensory cells of the vestibular end organs and vestibular ganglion cells. TRPV4 was found in the hair cells and supporting cells of the organ of Corti, in marginal cells of the stria vascularis, spiral ganglion cells, sensory cells, transitional cells, dark cells in the vestibular end organs, vestibular ganglion cells and epithelial cells of the endolymphatic sac.
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Affiliation(s)
- Masaya Takumida
- Department of Otolaryngology, Hiroshima University Faculty of Medicine, Hiroshima, Japan.
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24
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Sommer C. Serotonin in pain and analgesia: actions in the periphery. Mol Neurobiol 2005; 30:117-25. [PMID: 15475622 DOI: 10.1385/mn:30:2:117] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2003] [Accepted: 02/04/2004] [Indexed: 11/11/2022]
Abstract
The purpose of this article is to summarize recent findings on the role of serotonin in pain processing in the peripheral nervous system. Serotonin (5-hydroxtryptamine [5-HT]) is present in central and peripheral serotonergic neurons, it is released from platelets and mast cells after tissue injury, and it exerts algesic and analgesic effects depending on the site of action and the receptor subtype. After nerve injury, the 5-HT content in the lesioned nerve increases. 5-HT receptors of the 5-HT3 and 5-HT2A subtype are present on C-fibers. 5-HT, acting in combination with other inflammatory mediators, may ectopically excite and sensitize afferent nerve fibers, thus contributing to peripheral sensitization and hyperalgesia in inflammation and nerve injury.
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Affiliation(s)
- Claudia Sommer
- Department of Neurology, University of Würzburg, Germany.
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25
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van den Worm E, Nijkamp FP, Engels F. Nerve growth factor and the vanilloid receptor: partners in crime? Clin Exp Allergy 2004; 34:996-1000. [PMID: 15248840 DOI: 10.1111/j.1365-2222.2004.02012.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Linhart O, Obreja O, Kress M. The inflammatory mediators serotonin, prostaglandin E2 and bradykinin evoke calcium influx in rat sensory neurons. Neuroscience 2003; 118:69-74. [PMID: 12676138 DOI: 10.1016/s0306-4522(02)00960-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The inflammatory mediators bradykinin, prostaglandin E(2) and serotonin interact to excite and sensitize nociceptive neurons. All three mediators are coupled to signaling pathways that potentially induce rises in intracellular calcium concentration in other models. The aim of this study was therefore to investigate if the three mediators cause calcium rises in isolated rat sensory neurons that may explain their sensitizing action. Neurons exposed to serotonin, bradykinin, and prostaglandin E(2) exhibited reversible increases in intracellular calcium concentration, which were absent in calcium-free solution. The calcium increase induced by serotonin was preserved in the presence of extracellular cadmium suggesting calcium influx potentially through the serotonin receptor ion channel 5-HT(3). The bradykinin-induced calcium response was slower, showed pronounced tachyphylaxis and was absent in the presence of extracellular cadmium ions. Similar results were obtained for prostaglandin E(2) although the calcium rises were fast and not prone to tachyphylaxis. This suggests that prostaglandin E(2) as well as bradykinin via activation of G protein-coupled receptors seem to couple to calcium-permeant ion channels possibly the heat-transducing vanilloid receptor type 1 or related ion channels. The three mediators, however, did not cooperate to induce supra-additive calcium responses when applied simultaneously. In summary, our results suggest that the inflammatory mediators serotonin, prostaglandin E(2) and bradykinin induce calcium influx in sensory neurons. However, they do not utilize a calcium-dependent cooperative mechanism to facilitate proton-induced currents.
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MESH Headings
- Animals
- Bradykinin/metabolism
- Bradykinin/pharmacology
- Cadmium/metabolism
- Calcium/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cell Culture Techniques
- Dinoprostone/metabolism
- Dinoprostone/pharmacology
- Female
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Hyperalgesia/metabolism
- Hyperalgesia/physiopathology
- Inflammation Mediators/metabolism
- Inflammation Mediators/pharmacology
- Ion Channels/drug effects
- Ion Channels/metabolism
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Nociceptors/drug effects
- Nociceptors/metabolism
- Pain/metabolism
- Pain/physiopathology
- Rats
- Rats, Wistar
- Receptors, Drug/drug effects
- Receptors, Drug/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
- Receptors, Serotonin, 5-HT3
- Serotonin/metabolism
- Serotonin/pharmacology
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Affiliation(s)
- O Linhart
- Institut fur Physiologie und Experimentelle Pathophysiologie, Universitaetsstrasse 17, D-91054, Erlangen, Germany
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27
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Song XJ, Zhang JM, Hu SJ, LaMotte RH. Somata of nerve-injured sensory neurons exhibit enhanced responses to inflammatory mediators. Pain 2003; 104:701-709. [PMID: 12927643 DOI: 10.1016/s0304-3959(03)00167-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The effects of inflammatory mediators in modulating the activity of nerve-injured dorsal root ganglion (DRG) neurons were studied in rats in an in vitro nerve-DRG preparation 2-4 weeks after a loose ligation of the sciatic nerve (chronic constriction injury, CCI). An inflammatory soup (IS) of bradykinin, serotonin, prostaglandin E2 and histamine (each 10(-5) M, pH=7.4) was applied topically to the DRG. Evoked responses were recorded extracellularly from teased dorsal root fibers or intracellularly with sharp electrodes from somata of DRG neurons with myelinated (Abeta and Adelta) or unmyelinated (C) axons. IS increased the rate of ongoing spontaneous activity recorded from dorsal root fibers of CCI neurons and evoked activity in a subpopulation of previously 'silent' fibers in CCI rats but not those of unoperated controls. In comparison with DRG somata of control rats, those of CCI become more excitable as evidenced by a lower threshold to depolarizing current and a greater depolarization in response to IS. Inflammatory mediators, by increasing the excitability of DRG neurons, may contribute to paresthesiae, pain and hyperalgesia after peripheral nerve injury.
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Affiliation(s)
- Xue-Jun Song
- Parker College Research Institute, Dallas, TX, USA Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock, AR, USA The Fourth Military Medical University, Xi'an, People's Republic of China Department of Anesthesiology, Yale University School of Medicine, P.O. Box 208051, 333 Cedar Street, New Haven, CT 06520, USA
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28
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Zheng J, Dai C, Steyger PS, Kim Y, Vass Z, Ren T, Nuttall AL. Vanilloid receptors in hearing: altered cochlear sensitivity by vanilloids and expression of TRPV1 in the organ of corti. J Neurophysiol 2003; 90:444-55. [PMID: 12660354 PMCID: PMC3678390 DOI: 10.1152/jn.00919.2002] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Capsaicin, the vanilloid that selectively activates vanilloid receptors (VRs) on sensory neurons for noxious perception, has been reported to increase cochlear blood flow (CBF). VR-related receptors have also been found in the inner ear. This study aims to address the question as to whether VRs exist in the organ of Corti and play a role in cochlear physiology. Capsaicin or the more potent VR agonist, resiniferatoxin (RTX), was infused into the scala tympani of guinea pig cochlea, and their effects on cochlear sensitivity were investigated. Capsaicin (20 microM) elevated the threshold of auditory nerve compound action potential and reduced the magnitude of cochlear microphonic and electrically evoked otoacoustic emissions. These effects were reversible and could be blocked by a competitive antagonist, capsazepine. Application of 2 microM RTX resulted in cochlear sensitivity alterations similar to that by capsaicin, which could also be blocked by capsazepine. A desensitization phenomenon was observed in the case of prolonged perfusion with either capsaicin or RTX. Brief increase of CBF by capsaicin was confirmed, and the endocochlear potential was not decreased. Basilar membrane velocity (BM) growth functions near the best frequency and BM tuning were altered by capsaicin. Immunohistochemistry study revealed the presence of vanilloid receptor type 1 of the transient receptor potential channel family in the hair cells and supporting cells of the organ of Corti and the spiral ganglion cells of the cochlea. The results indicate that the main action of capsaicin is on outer hair cells and suggest that VRs in the cochlea play a role in cochlear homeostasis.
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Affiliation(s)
- Jiefu Zheng
- Oregon Hearing Research Center, Department of Otolaryngology/Head and Neck Surgery, Oregon Health & Science University Portland, Oregon 97239, USA
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Savidge J, Davis C, Shah K, Colley S, Phillips E, Ranasinghe S, Winter J, Kotsonis P, Rang H, McIntyre P. Cloning and functional characterization of the guinea pig vanilloid receptor 1. Neuropharmacology 2002; 43:450-6. [PMID: 12243775 DOI: 10.1016/s0028-3908(02)00122-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We have cloned a guinea pig Vanilloid receptor 1 (VR1) from a dorsal root ganglion cDNA library and expressed it in CHO cells. The receptor has been functionally characterized by measuring changes in intracellular calcium produced by capsaicin, low pH and noxious heat. Capsaicin produced a concentration-dependent increase in intracellular calcium in guinea pig VR1-CHO cells with an estimated EC(50) of 0.17 +/- 0.0065 micro M, similar to that previously reported for rat and human VR1. Olvanil and resiniferatoxin were also effective agonists (EC(50) values of 0.0087 +/- 0.0035 micro M and 0.067 +/- 0.014 micro M, respectively), but 12-phenylacetate 13-acetate 20-homovanillate (PPAHV) and anandamide showed little agonist activity up to 10 micro M. As with human and rat VR1, guinea pig VR1 was also activated by pH below 6.0 and by noxious heat (>42 degrees C). Capsazepine acted as an antagonist of capsaicin responses in guinea pig VR1-CHO cells (IC(50) of 0.324 +/- 0.041 micro M ), as seen at rat VR1. However, in contrast to its lack of activity against pH and heat responses at rat VR1, capsazepine was an effective antagonist of these responses at guinea pig VR1. Capsazepine displayed an IC(50) of 0.355 +/- 25 micro M against pH 5.5, and provided complete blockade of heat responses at 1 micro M. Thus, capsazepine can significantly inhibit calcium influx due to heat and pH 5.5 at guinea pig VR1 and human VR1 but is inactive against these activators at rat VR1.
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Affiliation(s)
- Jonathan Savidge
- Novartis Institute for Medical Sciences, 5 Gower Place, WC1E 6BN, London, UK
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30
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Gu Q, Lee LY. Alveolar hypercapnia augments pulmonary C-fiber responses to chemical stimulants: role of hydrogen ion. J Appl Physiol (1985) 2002; 93:181-8. [PMID: 12070203 DOI: 10.1152/japplphysiol.00062.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine whether the excitabilities of pulmonary C fibers to chemical and mechanical stimuli are altered by CO(2)-induced acidosis, single-unit pulmonary C-fiber activity was recorded in anesthetized, open-chest rats. Transient alveolar hypercapnia (HPC) was induced by administering CO(2)-enriched gas mixture (15% CO(2), balance air) via the respirator inlet for 30 s, which rapidly lowered the arterial blood pH from a baseline of 7.40 +/- 0.01 to 7.17 +/- 0.02. Alveolar HPC markedly increased the responses of these C-fiber afferents to several chemical stimulants. For example, the C-fiber response to right atrial injection of the same dose of capsaicin (0.25-1.0 microg/kg) was significantly increased from 3.07 +/- 0.70 impulses/s at control to 8.48 +/- 1.52 impulses/s during HPC (n = 27; P < 0.05), and this enhanced response returned to control within approximately 10 min after termination of HPC. Similarly, alveolar HPC also induced significant increases in the C-fiber responses to right atrial injections of phenylbiguanide (4-8 microg/kg) and adenosine (0.2 mg/kg). In contrast, HPC did not change the response of pulmonary C fibers to lung inflation. Furthermore, the peak response of these C fibers to capsaicin during HPC was greatly attenuated when the HPC-induced acidosis was buffered by infusion of bicarbonate (1.36-1.82 mmol. kg(-1). min(-1) for 35 s). In conclusion, alveolar HPC augments the responses of these afferents to various chemical stimulants, and this potentiating effect of CO(2) is mediated through the action of hydrogen ions on the C-fiber sensory terminals.
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Affiliation(s)
- Qihai Gu
- Department of Physiology, University of Kentucky Medical Center, Lexington 40536, USA
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31
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Abstract
Exposure to a class of airborne pollutants known as particulate matter (PM) is an environmental health risk of global proportions. PM is thought to initiate and/or exacerbate respiratory disorders, such as asthma and airway hyper-responsiveness and is epidemiologically associated with causing death in the elderly and those with pre-existing respiratory, or cardiopulmonary disease. Plausible mechanisms of action to explain PM inflammation and its susceptible sub-population component are lacking. This review describes a series of published studies which indicate that PM initiates airway inflammation through sensory neural pathways, specifically by activation of capsaicin-sensitive vanilloid (e.g. VRI) irritant receptors. These acid-sensitive receptors are located on the sensory C nerve fibers that innervate the airways as well as on various immune and non-immune airway target cells. The activation of these receptors results in the release of neuropeptides from the sensory terminals that innervate the airways. Their interactions with airway target cells, result in signs of inflammation (e.g. bronchoconstriction, vasodilation, histamine release, mucous secretion etc.). Our data have linked the activation of the VR1 receptors to the surface charge carried on the colloidal particulates which constitute PM pollution. Related studies have examined how genetic and non-genetic factors modify the sensitivity of these irritant receptors and enhance the inflammatory responsiveness to PM. In summary, this review proposes a mechanism by which neurogenic elements initiate and sustain PM-mediated airway inflammation. Although neurogenic influences have been appreciated in normal airway homeostasis, they have not, until now, been associated with PM toxicity. The sensitivity of the sensory nervous system to irritants and its interactions with pulmonary target tissues, should encourage neuroscientists to explore the relevance of neurogenic influences to toxic disorders involving other peripheral target systems.
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Affiliation(s)
- B Verones
- Neurotoxicology Division, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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32
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Heblich F, England S, Docherty RJ. Indirect actions of bradykinin on neonatal rat dorsal root ganglion neurones: a role for non-neuronal cells as nociceptors. J Physiol 2001; 536:111-21. [PMID: 11579161 PMCID: PMC2278851 DOI: 10.1111/j.1469-7793.2001.00111.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. In this study we have investigated the action of bradykinin (Bk) on cultured neonatal rat dorsal root ganglion (DRG) cells, with the aim of elucidating whether the neuronal response to Bk is influenced by association with non-neuronal satellite cells. 2. Bradykinin (100 nM) evoked an inward current (I(Bk)) in 51 of 58 voltage clamped DRG neurones (holding potential (V(h)) = -80 mV) that were in contact with non-neuronal satellite cells. 3. Bradykinin failed to evoke an inward current in isolated DRG neurones (V(h) = -80 mV) that were not in contact with non-neuronal satellite cells (n = 41). 4. The lack of neuronal response to Bk was not influenced by time in culture. Bradykinin failed to evoke a response in isolated neurones through 1-5 days in culture. By contrast neurones in contact with satellite cells responded to Bk throughout the same time period. 5. Failure of isolated neurones to respond to Bk was not due to the replating procedure or to selective subcellular distribution of receptors/ion channels to the processes rather than the somata of neurones. 6. Using Indo-1 AM microfluorimetry Bk (100 nM) was demonstrated to evoke an intracellular Ca(2+) increase (Ca(Bk)) in DRG neurones in contact with non-neuronal satellite cells and in isolated neurones. 7. These data suggest that the inward current response to Bk requires contact between DRG neurones and non-neuronal satellite cells. This implies an indirect mechanism of action for Bk via the non-neuronal cells, which may perform a nociceptive role. However, Bk can also act directly on the neurones, since it evokes Ca(Bk) in isolated neurones. The relationship between Ca(Bk) and the Bk-induced inward current is unknown at present.
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Affiliation(s)
- F Heblich
- Centre for Neuroscience, Sensory Function, Hodgkin Building, King's College London, Guy's Campus, London SE1 1UL, UK
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McIntyre P, McLatchie LM, Chambers A, Phillips E, Clarke M, Savidge J, Toms C, Peacock M, Shah K, Winter J, Weerasakera N, Webb M, Rang HP, Bevan S, James IF. Pharmacological differences between the human and rat vanilloid receptor 1 (VR1). Br J Pharmacol 2001; 132:1084-94. [PMID: 11226139 PMCID: PMC1572656 DOI: 10.1038/sj.bjp.0703918] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Vanilloid receptors (VR1) were cloned from human and rat dorsal root ganglion libraries and expressed in Xenopus oocytes or Chinese Hamster Ovary (CHO) cells. Both rat and human VR1 formed ligand gated channels that were activated by capsaicin with similar EC(50) values. Capsaicin had a lower potency on both channels, when measured electrophysiologically in oocytes compared to CHO cells (oocytes: rat=1.90+/-0.20 microM; human=1.90+/-0.30 microM: CHO cells: rat=0.20+/-0.06 microM; human=0.19+/-0.08 microM). In CHO cell lines co-expressing either rat or human VR1 and the calcium sensitive, luminescent protein, aequorin, the EC(50) values for capsaicin-induced responses were similar in both cell lines (rat=0.35+/-0.06 microM, human=0.53+/-0.03 microM). The threshold for activation by acidic solutions was lower for human VR1 channels than that for rat VR1 (EC(50) pH 5.49+/-0.04 and pH 5.78+/-0.09, respectively). The threshold for heat activation was identical (42 degrees C) for rat and human VR1. PPAHV was an agonist at rat VR1 (EC(50) between 3 and 10 microM) but was virtually inactive at the human VR1 (EC(50)>10 microM). Capsazepine and ruthenium red were both more potent at blocking the capsaicin response of human VR1 than rat VR1. Capsazepine blocked the human but not the rat VR1 response to low pH. Capsazepine was also more effective at inhibiting the noxious heat response of human than of rat VR1.
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Affiliation(s)
- P McIntyre
- Novartis Institute for Medical Sciences, 5 Gower Place, London WC1E 6BN, UK.
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Averbeck B, Reeh PW. Interactions of inflammatory mediators stimulating release of calcitonin gene-related peptide, substance P and prostaglandin E(2) from isolated rat skin. Neuropharmacology 2001; 40:416-23. [PMID: 11166334 DOI: 10.1016/s0028-3908(00)00171-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Inflammatory mediators acting directly on nociceptive primary afferents induce neuropeptide release. In this study we investigated interactions between bradykinin, serotonin, histamine, prostaglandin and acid pH in stimulating the release of substance P (SP), calcitonin gene-related peptide (CGRP) and prostaglandin E(2) (PGE(2)) from isolated flaps of rat back skin using enzyme immunoassays. Stimulation with bradykinin (10(-5) M) augmented the release of SP, CGRP and PGE(2) significantly. Serotonin, histamine and PGE(2) individually tested (10(-5) M) had no effect on neuropeptide release but they facilitated the bradykinin-evoked neuropeptide release. When bradykinin was combined with both serotonin and histamine, neither additional PGE(2) nor acid pH showed any further effect, suggesting that the facilitation had reached a maximum. Exposure of the skin to acid pH (6.1 or 5.2) significantly increased CGRP release. SP release was only slightly enhanced and PGE(2) release, in contrast, was suppressed by low pH stimulation, probably due to pH-dependent inhibition of phospholipase A(2). Treatment of the rats with flurbiprofen (25 mg/kg i.p.) one hour before dissection reduced PGE(2) to detection level and inhibited the CGRP secretion evoked by the combination of bradykinin, serotonin and histamine (all 10(-6) M). As this suppression could not be overcome by substitution of PGE(2) (10(-6) M), it is likely that exogenously applied PGE(2) differs in effect from endogenous, intracellularly synthesized prostaglandins that are accompanied by active intermediates and byproducts.
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Affiliation(s)
- B Averbeck
- Institute of Physiology and Experimental Pathophysiology, University of Erlangen-Nürnberg, 91054, Erlangen, Germany.
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de Plater GM, Milburn PJ, Martin RL. Venom from the platypus, Ornithorhynchus anatinus, induces a calcium-dependent current in cultured dorsal root ganglion cells. J Neurophysiol 2001; 85:1340-5. [PMID: 11248005 DOI: 10.1152/jn.2001.85.3.1340] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The platypus (Ornithorhynchus anatinus), a uniquely Australian species, is one of the few living venomous mammals. Although envenomation of humans by many vertebrate and invertebrate species results in pain, this is often not the principal symptom of envenomation. However, platypus envenomation results in an immediate excruciating pain that develops into a very long-lasting hyperalgesia. We have previously shown that the venom contains a C-type natriuretic peptide that causes mast cell degranulation, and this probably contributes to the development of the painful response. Now we demonstrate that platypus venom has a potent action on putative nociceptors. Application of the venom to small to medium diameter dorsal root ganglion cells for 10 s resulted in an inward current lasting several minutes when the venom was diluted in buffer at pH 6.1 but not at pH 7.4. The venom itself has a pH of 6.3. The venom activated a current with a linear current-voltage relationship between -100 and -25 mV and with a reversal potential of -11 mV. Ion substitution experiments indicate that the current is a nonspecific cationic current. The response to the venom was blocked by the membrane-permeant Ca(2+)-ATPase inhibitor, thapsigargin, and by the tyrosine- and serine-kinase inhibitor, k252a. Thus the response appears to be dependent on calcium release from intracellular stores. The identity of the venom component(s) that is responsible for the responses we have described is yet to be determined but is probably not the C-type natriuretic peptide or the defensin-like peptides that are present in the venom.
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Affiliation(s)
- G M de Plater
- Division of Neuroscience, Australian National University, Canberra, ACT 0200, Australia
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Reeh PW, Pethö G. Nociceptor excitation by thermal sensitization--a hypothesis. PROGRESS IN BRAIN RESEARCH 2001; 129:39-50. [PMID: 11098680 DOI: 10.1016/s0079-6123(00)29004-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- P W Reeh
- Institute of Physiology and Experimental Pathophysiology, Erlangen, Germany.
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Veronesi B, Oortgiesen M, Roy J, Carter JD, Simon SA, Gavett SH. Vanilloid (capsaicin) receptors influence inflammatory sensitivity in response to particulate matter. Toxicol Appl Pharmacol 2000; 169:66-76. [PMID: 11076698 DOI: 10.1006/taap.2000.9040] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The signs of airway inflammation and hyperresponsiveness that occur in animals exposed to air pollutants are often strain- and species-specific. To investigate the underlying causes of this phenomenon, BALB/c and C57bl/6 mice were exposed intratracheally to residual oil fly ash (ROFA, 3 mg/kg) and examined after 24 h for signs of airway inflammation. BALB/c showed significantly higher numbers of neutrophils and increased airway hyperresponsiveness in response to methacholine challenge, whereas B6 mice showed no significant change in either inflammatory endpoint. To determine the underlying cause of this strain specificity, cultures of dorsal root ganglion (DRG) sensory neurons, which innervate the upper airways in situ, were explanted from both BALB/c and B6 fetal mice. After 5-7 days in culture, they were exposed to ROFA, other urban and industrial particulate matter (PM; e.g., oil fly ash, woodstove, Mt. St. Helen, St. Louis, Ottawa, coal fly ash) or to prototype irritants (e.g., capsaicin 3-10 microM, pH 5.0 and 6.5). In all instances (except for woodstove), DRG neurons from BALB/c mice released significantly higher levels of the pro-inflammatory cytokine IL-6 into their nutrient media relative to neurons from B6 mice. This cytokine release could be significantly reduced for all PM treated cultures (except woodstove) by pretreatment of cultures with capsazepine (CPZ), a competitive antagonist of vanilloid receptors. DRG neurons, cultured from BALB/c and B6 neonates, were loaded with Fluo-3 AM and exposed to the prototype irritants, acid pH (5.0, 6.5), or capsaicin (3, 10 microM). Analysis of their increases in intracellular calcium showed that significantly higher numbers of BALB/c neurons responded to these prototype irritants, relative to B6 neurons. Morphometric analysis of BALB/c neurons, histochemically stained with cobalt to label neurons bearing capsaicin-sensitive receptors, showed a significantly higher level of stained neurons relative to B6 neurons. Finally, semiquantitative RT-PCR showed a higher expression of VR1 receptor mRNA in DRG and spinal cord taken from neonatal BALB/c mice relative to B6 mice. Taken together, these data suggest that capsaicin and acid-sensitive irritant receptors, located on somatosensory cell bodies and their nerve fiber terminals, subserve PM-induced airway inflammation and are quantitatively different in responsive and nonresponsive mouse strains.
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MESH Headings
- Air Pollutants/toxicity
- Animals
- Animals, Newborn
- Bronchial Hyperreactivity/chemically induced
- Bronchial Hyperreactivity/physiopathology
- Capsaicin/metabolism
- Carbon/administration & dosage
- Carbon/toxicity
- Cell Survival/drug effects
- Cells, Cultured
- Coal Ash
- Dose-Response Relationship, Drug
- Female
- Fetus/cytology
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/embryology
- Ganglia, Spinal/metabolism
- Interleukin-6/metabolism
- Intubation, Intratracheal
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Particulate Matter
- Pregnancy
- RNA/metabolism
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Species Specificity
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Affiliation(s)
- B Veronesi
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
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Averbeck B, Izydorczyk I, Kress M. Inflammatory mediators release calcitonin gene-related peptide from dorsal root ganglion neurons of the rat. Neuroscience 2000; 98:135-40. [PMID: 10858619 DOI: 10.1016/s0306-4522(00)00095-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interactions between the inflammatory mediators bradykinin, serotonin, prostaglandin E(2) and acid pH were studied in rat dorsal root ganglion neurons in culture. For this purpose, the cultures were stimulated by inflammatory mediators (bradykinin, serotonin, prostaglandin E(2), 10(-5)M each) or acid solution (pH 6.1) for 5 min and the content of calcitonin gene-related peptide was determined in the supernatant before, during and after stimulation, using an enzyme immunoassay. Acid solution resulted in a threefold increase of the basal calcitonin gene-related peptide release which was entirely dependent on the presence of extracellular calcium. The release could not be blocked by the addition of the capsaicin antagonist capsazepine (10(-5)M). Bradykinin (10(-5)M) caused a 50% increase of the basal calcitonin gene-related peptide release which was again dependent on the presence of extracellular calcium, whereas serotonin and prostaglandin E(2) were each ineffective at 10(-5)M concentration. The combination of bradykinin, serotonin and prostaglandin E(2) led to a fivefold increase of the calcitonin gene-related peptide release which could not be further enhanced by acidification. The competitive capsaicin receptor antagonist capsazepine (10(-5)M) significantly reduced the release induced by the combination of bradykinin, serotonin and prostaglandin E(2). It is suggested that the inflammatory mediators co-operate and together may act as endogenous agonists at the capsaicin receptor to cause calcium influx and consecutive neuropeptide release.
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Affiliation(s)
- B Averbeck
- Institute of Pharmacology and Toxicology, Dresden University of Technology, Karl-Marx-Strasse 3, D-01109, Dresden, Germany
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Habelt C, Kessler F, Distler C, Kress M, Reeh PW. Interactions of inflammatory mediators and low pH not influenced by capsazepine in rat cutaneous nociceptors. Neuroreport 2000; 11:973-6. [PMID: 10790866 DOI: 10.1097/00001756-200004070-00015] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The rat skin-saphenous nerve preparation was used to record from mechano-heat sensitive C-fibers whose receptive fields were superfused with various solutions of low pH and of bradykinin, serotonin and prostaglandin E2. Only synchronous application of protons and mediators resulted in a significant nearly three-fold augmentation of the nociceptive pH response, and capsazepine (10(-5) M) did not block this short-lived enhancement. Thus, it does not seem to involve the capsaicin receptor (VRI) which is in contrast to a previous finding from cultured sensory neurons.
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Affiliation(s)
- C Habelt
- Institute of Physiology and Experimental Pathophysiology, Erlangen, Germany
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40
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Segond von Banchet G, Petrow PK, Bräuer R, Schaible HG. Monoarticular antigen-induced arthritis leads to pronounced bilateral upregulation of the expression of neurokinin 1 and bradykinin 2 receptors in dorsal root ganglion neurons of rats. ARTHRITIS RESEARCH 2000; 2:424-7. [PMID: 11056677 PMCID: PMC17819 DOI: 10.1186/ar121] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2000] [Revised: 07/03/2000] [Accepted: 07/07/2000] [Indexed: 11/10/2022]
Abstract
STATEMENT OF FINDINGS: This study describes the upregulation of neurokinin 1 and bradykinin 2 receptors in dorsal root ganglion (DRG) neurons in the course of antigen-induced arthritis (AIA) in the rat knee. In the acute phase of AIA, which was characterized by pronounced hyperalgesia, there was a substantial bilateral increase in the proportion of lumbar DRG neurons that express neurokinin 1 receptors (activated by substance P) and bradykinin 2 receptors. In the chronic phase the upregulation of bradykinin 2 receptors persisted on the side of inflammation. The increase in the receptor expression is relevant for the generation of acute and chronic inflammatory pain.
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Abstract
The highly disagreeable sensation of pain results from an extraordinarily complex and interactive series of mechanisms integrated at all levels of the neuroaxis, from the periphery, via the dorsal horn to higher cerebral structures. Pain is usually elicited by the activation of specific nociceptors ('nociceptive pain'). However, it may also result from injury to sensory fibres, or from damage to the CNS itself ('neuropathic pain'). Although acute and subchronic, nociceptive pain fulfils a warning role, chronic and/or severe nociceptive and neuropathic pain is maladaptive. Recent years have seen a progressive unravelling of the neuroanatomical circuits and cellular mechanisms underlying the induction of pain. In addition to familiar inflammatory mediators, such as prostaglandins and bradykinin, potentially-important, pronociceptive roles have been proposed for a variety of 'exotic' species, including protons, ATP, cytokines, neurotrophins (growth factors) and nitric oxide. Further, both in the periphery and in the CNS, non-neuronal glial and immunecompetent cells have been shown to play a modulatory role in the response to inflammation and injury, and in processes modifying nociception. In the dorsal horn of the spinal cord, wherein the primary processing of nociceptive information occurs, N-methyl-D-aspartate receptors are activated by glutamate released from nocisponsive afferent fibres. Their activation plays a key role in the induction of neuronal sensitization, a process underlying prolonged painful states. In addition, upon peripheral nerve injury, a reduction of inhibitory interneurone tone in the dorsal horn exacerbates sensitized states and further enhance nociception. As concerns the transfer of nociceptive information to the brain, several pathways other than the classical spinothalamic tract are of importance: for example, the postsynaptic dorsal column pathway. In discussing the roles of supraspinal structures in pain sensation, differences between its 'discriminative-sensory' and 'affective-cognitive' dimensions should be emphasized. The purpose of the present article is to provide a global account of mechanisms involved in the induction of pain. Particular attention is focused on cellular aspects and on the consequences of peripheral nerve injury. In the first part of the review, neuronal pathways for the transmission of nociceptive information from peripheral nerve terminals to the dorsal horn, and therefrom to higher centres, are outlined. This neuronal framework is then exploited for a consideration of peripheral, spinal and supraspinal mechanisms involved in the induction of pain by stimulation of peripheral nociceptors, by peripheral nerve injury and by damage to the CNS itself. Finally, a hypothesis is forwarded that neurotrophins may play an important role in central, adaptive mechanisms modulating nociception. An improved understanding of the origins of pain should facilitate the development of novel strategies for its more effective treatment.
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Affiliation(s)
- M J Millan
- Institut de Recherches Servier, Psychopharmacology Department, Paris, France
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Stucky CL, Abrahams LG, Seybold VS. Bradykinin increases the proportion of neonatal rat dorsal root ganglion neurons that respond to capsaicin and protons. Neuroscience 1998; 84:1257-65. [PMID: 9578411 DOI: 10.1016/s0306-4522(97)00572-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A number of studies have examined bradykinin-induced sensitization of primary afferent neurons to mechanical or thermal stimuli. However, bradykinin-induced sensitization to other chemical stimuli has not been systematically addressed. We used primary cultures of dorsal root ganglion neurons from neonatal rats to determine whether bradykinin alters the responsiveness of individual neurons to capsaicin and protons. An increase in the concentration of free intracellular Ca2+ was used as a measure of a response to capsaicin or low pH. Pretreatment with bradykinin (30 nM) increased the proportion of "intermediate-size" (240-320 microm2) dorsal root ganglion neurons that responded to capsaicin (100 nM) or low pH (6.1). However, among "small-size" (160-239 microm2) neurons, bradykinin increased the proportion of neurons that responded to low pH (6.1) but not to capsaicin (10 or 100 nM). Because treatment with arachidonic acid (10 microM) did not mimic the effect of bradykinin and inhibition of cyclo-oxygenase and lipoxygenase with 5,8,11,14-eicosatetraynoic acid (10 microM) did not inhibit the effect of bradykinin on the response to capsaicin, it is not likely that the bradykinin-induced enhancement of neuronal responsiveness is mediated by arachidonic acid or its metabolites in this model. These results support the hypothesis that bradykinin sensitizes primary afferent neurons to other chemicals such as protons that are present in inflamed tissue, particularly by recruiting additional sensory neurons to respond to a given chemical stimulus. An increase in the number of responsive nociceptors that innervate inflamed tissue would contribute to hyperalgesia via spatial summation on spinal neurons in the pathway for pain. Furthermore, since bradykinin enhanced the responsiveness of small-size neurons that responded to protons but not to capsaicin, these data suggest that bradykinin-induced sensitization to protons and capsaicin occur by different mechanisms.
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Affiliation(s)
- C L Stucky
- Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455, USA
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Vyklický L, Knotková-Urbancová H, Vitásková Z, Vlachová V, Kress M, Reeh PW. Inflammatory mediators at acidic pH activate capsaicin receptors in cultured sensory neurons from newborn rats. J Neurophysiol 1998; 79:670-6. [PMID: 9463430 DOI: 10.1152/jn.1998.79.2.670] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Whole cell membrane currents induced by the inflammatory mediators, bradykinin, 5-hydroxytryptamine (5-HT) and prostaglandin E2, were investigated in capsaicin-sensitive dorsal root ganglion (DRG) neurons from newborn rats grown on a monolayer of hippocampal glia without nerve growth factor (NGF). When firmly attached to an underlying cell, the neurons survived >14 days without growing extensive processes. A majority of the small diameter neurons ( approximately 80%) exhibited sensitivity to capsaicin (3-6 muM) and this was enhanced in solution of low pH. In acidic extracellular solution (pH 6.1), the combination of bradykinin (10 microM), 5-HT (10 microM) and prostaglandin E2 (1 microM) induced an inward membrane current in all capsaicin-sensitive DRG neurons (n = 43). The current exceeded the sustained, low pH-induced membrane current by 205 +/- 53 (SE) pA. The combination of acidic inflammatory mediators was ineffective in cells that were insensitive to capsaicin. In capsaicin-sensitive neurons, the inflammatory mediators when applied singly or in any combination of two, induced no membrane currents or small current at pH 7.3 and 6.1. Capsazepine (10 microM), the capsaicin antagonist, completely inhibited the facilitatory action of inflammatory mediator combination but not the sustained inward current induced by acidic extracellular solution (pH 6.1 or 5.5). It is suggested that the inflammatory mediators, bradykinin,5-HT, and prostaglandin E2 together act as endogenous mediators at capsaicin receptors to generate an inward current when the ion channel is protonized.
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Affiliation(s)
- L Vyklický
- Institute of Physiology, AS CR, 14220 Prague 4, Czech Republic
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