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Pitschmann V, Hon Z. Drugs as Chemical Weapons: Past and Perspectives. TOXICS 2023; 11:52. [PMID: 36668778 PMCID: PMC9866636 DOI: 10.3390/toxics11010052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/27/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
The emergence of modern chemical weapons and chemical warfare is traditionally associated with World War I, but the use of poisons in the military has its roots deep in the past. The sources of these poisons have always been natural agents that also served as medicines. This relationship between poison and medicine, and nowadays between chemical warfare and medicine, or between 'military chemistry' and pharmacy, appears to be very important for understanding not only the history but also the possible future of both phenomena. This article looks at some historical examples of the use of drugs as chemical weapons and, conversely, the use of chemical weapons as medicines. It seeks to find answers to some questions that are particularly relevant to the implementation of the Chemical Weapons Convention, which aims to achieve a world without chemical warfare.
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Affiliation(s)
- Vladimír Pitschmann
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Sítná sq. 3105, 272 01 Kladno, Czech Republic
- ORITEST spol. s r.o., Čerčanská 640/30, 140 00 Prague, Czech Republic
| | - Zdeněk Hon
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Sítná sq. 3105, 272 01 Kladno, Czech Republic
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2
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Javed H, Johnson AM, Challagandla AK, Emerald BS, Shehab S. Cutaneous Injection of Resiniferatoxin Completely Alleviates and Prevents Nerve-Injury-Induced Neuropathic Pain. Cells 2022; 11:cells11244049. [PMID: 36552812 PMCID: PMC9776507 DOI: 10.3390/cells11244049] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/29/2022] [Accepted: 12/09/2022] [Indexed: 12/16/2022] Open
Abstract
Fifth lumbar (L5) nerve injury in rodent produces neuropathic manifestations in the corresponding hind paw. The aim of this study was to investigate the effect of cutaneous injection of resiniferatoxin (RTX), a TRPV1 receptor agonist, in the rat's hind paw on the neuropathic pain induced by L5 nerve injury. The results showed that intraplantar injection of RTX (0.002%, 100 µL) (1) completely reversed the development of chronic thermal and mechanical hypersensitivity; (2) completely prevented the development of nerve-injury-induced thermal and mechanical hypersensitivity when applied one week earlier; (3) caused downregulation of nociceptive pain markers, including TRPV1, IB4 and CGRP, and upregulation of VIP in the ipsilateral dorsal horn of spinal cord and dorsal root ganglion (DRG) immunohistochemically and a significant reduction in the expression of TRPV1 mRNA and protein in the ipsilateral DRG using Western blot and qRT-PCR techniques; (4) caused downregulation of PGP 9.5- and CGRP-immunoreactivity in the injected skin; (5) produced significant suppression of c-fos expression, as a neuronal activity marker, in the spinal neurons in response to a second intraplantar RTX injection two weeks later. This work identifies the ability of cutaneous injection of RTX to completely alleviate and prevent the development of different types of neuropathic pain in animals and humans.
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3
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Imaging the influence of peripheral TRPV1-signaling on cerebral nociceptive processing applying fMRI-based graph theory in a resiniferatoxin rat model. PLoS One 2022; 17:e0266669. [PMID: 35482725 PMCID: PMC9049522 DOI: 10.1371/journal.pone.0266669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 03/24/2022] [Indexed: 11/19/2022] Open
Abstract
Resiniferatoxin (RTX), an extract from the spurge plant Euphorbia resinifera, is a potent agonist of the transient receptor potential cation channel subfamily V member 1 (TRPV1), mainly expressed on peripheral nociceptors—a prerequisite for nociceptive heat perception. Systemic overdosing of RTX can be used to desensitize specifically TRPV1-expressing neurons, and was therefore utilized here to selectively characterize the influence of TRPV1-signaling on central nervous system (CNS) temperature processing. Resting state and CNS temperature processing of male rats were assessed via functional magnetic resonance imaging before and after RTX injection. General linear model-based and graph-theoretical network analyses disentangled the underlying distinct CNS circuitries. At baseline, rats displayed an increase of nociception-related response amplitude and activated brain volume that correlated highly with increasing stimulation temperatures. In contrast, RTX-treated rats showed a clear disruption of thermal nociception, reflected in a missing increase of CNS responses to temperatures above 48°C. Graph-theoretical analyses revealed two distinct brain subnetworks affected by RTX: one subcortical (brainstem, lateral and medial thalamus, hippocampus, basal ganglia and amygdala), and one cortical (primary sensory, motor and association cortices). Resting state analysis revealed first, that peripheral desensitization of TRPV1-expressing neurons did not disrupt the basic resting-state-network of the brain. Second, only at baseline, but not after RTX, noxious stimulation modulated the RS-network in regions associated with memory formation (e.g. hippocampus). Altogether, the combination of whole-brain functional magnetic resonance imaging and RTX-mediated desensitization of TRPV1-signaling provided further detailed insight into cerebral processing of noxious temperatures.
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4
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Comes N, Gasull X, Callejo G. Proton Sensing on the Ocular Surface: Implications in Eye Pain. Front Pharmacol 2021; 12:773871. [PMID: 34899333 PMCID: PMC8652213 DOI: 10.3389/fphar.2021.773871] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/09/2021] [Indexed: 01/15/2023] Open
Abstract
Protons reaching the eyeball from exogenous acidic substances or released from damaged cells during inflammation, immune cells, after tissue injury or during chronic ophthalmic conditions, activate or modulate ion channels present in sensory nerve fibers that innervate the ocular anterior surface. Their identification as well as their role during disease is critical for the understanding of sensory ocular pathophysiology. They are likely to mediate some of the discomfort sensations accompanying several ophthalmic formulations and may represent novel targets for the development of new therapeutics for ocular pathologies. Among the ion channels expressed in trigeminal nociceptors innervating the anterior surface of the eye (cornea and conjunctiva) and annex ocular structures (eyelids), members of the TRP and ASIC families play a critical role in ocular acidic pain. Low pH (pH 6) activates TRPV1, a polymodal ion channel also activated by heat, capsaicin and hyperosmolar conditions. ASIC1, ASIC3 and heteromeric ASIC1/ASIC3 channels present in ocular nerve terminals are activated at pH 7.2–6.5, inducing pain by moderate acidifications of the ocular surface. These channels, together with TRPA1, are involved in acute ocular pain, as well as in painful sensations during allergic keratoconjunctivitis or other ophthalmic conditions, as blocking or reducing channel expression ameliorates ocular pain. TRPV1, TRPA1 and other ion channels are also present in corneal and conjunctival cells, promoting inflammation of the ocular surface after injury. In addition to the above-mentioned ion channels, members of the K2P and P2X ion channel families are also expressed in trigeminal neurons, however, their role in ocular pain remains unclear to date. In this report, these and other ion channels and receptors involved in acid sensing during ocular pathologies and pain are reviewed.
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Affiliation(s)
- Núria Comes
- Neurophysiology Laboratory, Department of Biomedicine, Medical School, Institute of Neurosciences, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Xavier Gasull
- Neurophysiology Laboratory, Department of Biomedicine, Medical School, Institute of Neurosciences, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Gerard Callejo
- Neurophysiology Laboratory, Department of Biomedicine, Medical School, Institute of Neurosciences, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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5
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Ishida H, Zhang Y, Gomez R, Shannonhouse J, Son H, Banik R, Kim YS. In Vivo Calcium Imaging Visualizes Incision-Induced Primary Afferent Sensitization and Its Amelioration by Capsaicin Pretreatment. J Neurosci 2021; 41:8494-8507. [PMID: 34452938 PMCID: PMC8513701 DOI: 10.1523/jneurosci.0457-21.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 02/06/2023] Open
Abstract
Previous studies have shown that infiltration of capsaicin into the surgical site can prevent incision-induced spontaneous pain like behaviors and heat hyperalgesia. In the present study, we aimed to monitor primary sensory neuron Ca2+ activity in the intact dorsal root ganglia (DRG) using Pirt-GCaMP3 male and female mice pretreated with capsaicin or vehicle before the plantar incision. Intraplantar injection of capsaicin (0.05%) significantly attenuated spontaneous pain, mechanical, and heat hypersensitivity after plantar incision. The Ca2+ response in in vivo DRG and in in situ spinal cord was significantly enhanced in the ipsilateral side compared with contralateral side or naive control. Primary sensory nerve fiber length was significantly decreased in the incision skin area in capsaicin-pretreated animals detected by immunohistochemistry and placental alkaline phosphatase (PLAP) staining. Thus, capsaicin pretreatment attenuates incisional pain by suppressing Ca2+ response because of degeneration of primary sensory nerve fibers in the skin.SIGNIFICANCE STATEMENT Postoperative surgery pain is a major health and economic problem worldwide with ∼235 million major surgical procedures annually. Approximately 50% of these patients report uncontrolled or poorly controlled postoperative pain. However, mechanistic studies of postoperative surgery pain in primary sensory neurons have been limited to in vitro models or small numbers of neurons. Using an innovative, distinctive, and interdisciplinary in vivo populational dorsal root ganglia (DRG) imaging (>1800 neurons/DRG) approach, we revealed increased DRG neuronal Ca2+ activity from postoperative pain mouse model. This indicates widespread DRG primary sensory neuron plasticity. Increased neuronal Ca2+ activity occurs among various sizes of neurons but mostly in small-diameter and medium-diameter nociceptors. Capsaicin pretreatment as a therapeutic option significantly attenuates Ca2+ activity and postoperative pain.
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Affiliation(s)
- Hirotake Ishida
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
| | - Yan Zhang
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
| | - Ruben Gomez
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
| | - John Shannonhouse
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
| | - Hyeonwi Son
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
| | - Ratan Banik
- Department of Anesthesiology, School of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455
| | - Yu Shin Kim
- Department of Oral and Maxillofacial Surgery, University of Texas Health and Science Center at San Antonio, Texas, 78229
- Programs in Integrated Biomedical Sciences, Translational Sciences, Biomedical Engineering, Radiological Sciences, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229
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Middleton SJ, Perez-Sanchez J, Dawes JM. The structure of sensory afferent compartments in health and disease. J Anat 2021; 241:1186-1210. [PMID: 34528255 PMCID: PMC9558153 DOI: 10.1111/joa.13544] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/12/2021] [Accepted: 08/30/2021] [Indexed: 12/20/2022] Open
Abstract
Primary sensory neurons are a heterogeneous population of cells able to respond to both innocuous and noxious stimuli. Like most neurons they are highly compartmentalised, allowing them to detect, convey and transfer sensory information. These compartments include specialised sensory endings in the skin, the nodes of Ranvier in myelinated axons, the cell soma and their central terminals in the spinal cord. In this review, we will highlight the importance of these compartments to primary afferent function, describe how these structures are compromised following nerve damage and how this relates to neuropathic pain.
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Affiliation(s)
- Steven J Middleton
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - John M Dawes
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Iadarola MJ, Brown DC, Nahama A, Sapio MR, Mannes AJ. Pain Treatment in the Companion Canine Model to Validate Rodent Results and Incentivize the Transition to Human Clinical Trials. Front Pharmacol 2021; 12:705743. [PMID: 34421597 PMCID: PMC8375595 DOI: 10.3389/fphar.2021.705743] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/14/2021] [Indexed: 12/14/2022] Open
Abstract
One of the biggest challenges for analgesic drug development is how to decide if a potential analgesic candidate will work in humans. What preclinical data are the most convincing, incentivizing and most predictive of success? Such a predicament is not unique to analgesics, and the pain field has certain advantages over drug development efforts in areas like neuropsychiatry where the etiological origins are either unknown or difficult to ascertain. For pain, the origin of the problem frequently is known, and the causative peripheral tissue insult might be observable. The main conundrum centers around evaluation of translational cell- and rodent-based results. While cell and rodent models are undeniably important first steps for screening, probing mechanism of action, and understanding factors of adsorption, distribution metabolism and excretion, two questions arise from such studies. First, are they reliable indicators of analgesic performance of a candidate drug in human acute and chronic pain? Second, what additional model systems might be capable of increasing translational confidence? We address this second question by assessing, primarily, the companion canine model, which can provide particularly strong predictive information for candidate analgesic agents in humans. This statement is mainly derived from our studies with resiniferatoxin (RTX) a potent TRPV1 agonist but also from protein therapeutics using a conjugate of Substance P and saporin. Our experience, to date, is that rodent models might be very well suited for acute pain translation, but companion canine models, and other large animal studies, can augment initial discovery research using rodent models for neuropathic or chronic pain. The larger animal models also provide strong translational predictive capacity for analgesic performance in humans, better predict dosing parameters for human trials and provide insight into behavior changes (bladder, bowel, mood, etc.) that are not readily assessed in laboratory animals. They are, however, not without problems that can be encountered with any experimental drug treatment or clinical trial. It also is important to recognize that pain treatment is a major veterinary concern and is an intrinsically worthwhile endeavor for animals as well as humans.
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Affiliation(s)
- Michael J Iadarola
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD, United States
| | | | | | - Matthew R Sapio
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD, United States
| | - Andrew J Mannes
- Department of Perioperative Medicine, Clinical Center, NIH, Bethesda, MD, United States
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Rinwa P, Calvo-Enrique L, Zhang MD, Nyengaard JR, Karlsson P, Ernfors P. Demise of nociceptive Schwann cells causes nerve retraction and pain hyperalgesia. Pain 2021; 162:1816-1827. [PMID: 33979318 PMCID: PMC8120683 DOI: 10.1097/j.pain.0000000000002169] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/11/2020] [Accepted: 11/18/2020] [Indexed: 12/14/2022]
Abstract
ABSTRACT Recent findings indicate that nociceptive nerves are not "free", but similar to touch and pressure sensitive nerves, terminate in an end-organ in mice. This sensory structure consists of the nociceptive nerves and specialized nociceptive Schwann cells forming a mesh-like organ in subepidermis with pain transduction initiated at both these cellular constituents. The intimate relation of nociceptive nerves with nociceptive Schwann cells in mice raises the question whether defects in nociceptive Schwann cells can by itself contribute to pain hyperalgesia, nerve retraction, and peripheral neuropathy. We therefore examined the existence of nociceptive Schwann cells in human skin and their possible contribution to neuropathy and pain hyperalgesia in mouse models. Similar to mouse, human skin contains SOX10+/S100B+/AQP1+ Schwann cells in the subepidermal border that have extensive processes, which are intimately associated with nociceptive nerves projecting into epidermis. The ablation of nociceptive Schwann cells in mice resulted in nerve retraction and mechanical, cold, and heat hyperalgesia. Conversely, ablating the nociceptive nerves led to a retraction of epidermal Schwann cell processes, changes in nociceptive Schwann cell soma morphology, heat analgesia, and mechanical hyperalgesia. Our results provide evidence for a nociceptive sensory end-organ in the human skin and using animal models highlight the interdependence of the nerve and the nociceptive Schwann cell. Finally, we show that demise of nociceptive Schwann cells is sufficient to cause neuropathic-like pain in the mouse.
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Affiliation(s)
- Puneet Rinwa
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - Laura Calvo-Enrique
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - Ming-Dong Zhang
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - Jens Randel Nyengaard
- Department of Clinical Medicine—Core Centre for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
- Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University Hospital, Aarhus, Denmark
| | - Páll Karlsson
- Department of Clinical Medicine—Core Centre for Molecular Morphology, Section for Stereology and Microscopy, Aarhus University, Aarhus, Denmark
- Danish Pain Research Center, Aarhus University, Aarhus, Denmark
| | - Patrik Ernfors
- Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden
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Small A, Fisher AD, Lee C, Colditz I. Analgesia for Sheep in Commercial Production: Where to Next? Animals (Basel) 2021; 11:ani11041127. [PMID: 33920025 PMCID: PMC8070992 DOI: 10.3390/ani11041127] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/08/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on industry to alleviate pain associated with husbandry practices, injury and illness. Although a number of analgesic solutions are now available for sheep, providing some amelioration of the acute pain responses, this review has highlighted a number of potential areas for further research. Abstract Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.
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Affiliation(s)
- Alison Small
- CSIRO Agriculture & Food, Locked Bag 1, Armidale, NSW 2350, Australia; (C.L.); (I.C.)
- Correspondence: ; Tel.: +61-2-6776-1435
| | - Andrew David Fisher
- Animal Welfare Science Centre, University of Melbourne, Parkville, VIC 3052, Australia;
| | - Caroline Lee
- CSIRO Agriculture & Food, Locked Bag 1, Armidale, NSW 2350, Australia; (C.L.); (I.C.)
| | - Ian Colditz
- CSIRO Agriculture & Food, Locked Bag 1, Armidale, NSW 2350, Australia; (C.L.); (I.C.)
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Fight fire with fire: Neurobiology of capsaicin-induced analgesia for chronic pain. Pharmacol Ther 2020; 220:107743. [PMID: 33181192 DOI: 10.1016/j.pharmthera.2020.107743] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/04/2020] [Indexed: 12/12/2022]
Abstract
Capsaicin, the pungent ingredient in chili peppers, produces intense burning pain in humans. Capsaicin selectively activates the transient receptor potential vanilloid 1 (TRPV1), which is enriched in nociceptive primary afferents, and underpins the mechanism for capsaicin-induced burning pain. Paradoxically, capsaicin has long been used as an analgesic. The development of topical patches and injectable formulations containing capsaicin has led to application in clinical settings to treat chronic pain conditions, such as neuropathic pain and the potential to treat osteoarthritis. More detailed determination of the neurobiological mechanisms of capsaicin-induced analgesia should provide the logical rationale for capsaicin therapy and help to overcome the treatment's limitations, which include individual differences in treatment outcome and procedural discomfort. Low concentrations of capsaicin induce short-term defunctionalization of nociceptor terminals. This phenomenon is reversible within hours and, hence, likely does not account for the clinical benefit. By contrast, high concentrations of capsaicin lead to long-term defunctionalization mediated by the ablation of TRPV1-expressing afferent terminals, resulting in long-lasting analgesia persisting for several months. Recent studies have shown that capsaicin-induced Ca2+/calpain-mediated ablation of axonal terminals is necessary to produce long-lasting analgesia in a mouse model of neuropathic pain. In combination with calpain, axonal mitochondrial dysfunction and microtubule disorganization may also contribute to the longer-term effects of capsaicin. The analgesic effects subside over time in association with the regeneration of the ablated afferent terminals. Further determination of the neurobiological mechanisms of capsaicin-induced analgesia should lead to more efficacious non-opioidergic analgesic options with fewer adverse side effects.
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11
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Abstract
The transient receptor potential vanilloid-1 (TRPV1) is a non-specific cation channel known for its sensitivity to pungent vanilloid compound (i.e. capsaicin) and noxious stimuli, including heat, low pH or inflammatory mediators. TRPV1 is found in the somatosensory system, particularly primary afferent neurons that respond to damaging or potentially damaging stimuli (nociceptors). Stimulation of TRPV1 evokes a burning sensation, reflecting a central role of the channel in pain. Pharmacological and genetic studies have validated TRPV1 as a therapeutic target in several preclinical models of chronic pain, including cancer, neuropathic, postoperative and musculoskeletal pain. While antagonists of TRPV1 were found to be a valuable addition to the pain therapeutic toolbox, their clinical use has been limited by detrimental side effects, such as hyperthermia. In contrast, capsaicin induces a prolonged defunctionalisation of nociceptors and thus opened the door to the development of a new class of therapeutics with long-lasting pain-relieving effects. Here we review the list of TRPV1 agonists undergoing clinical trials for chronic pain management, and discuss new indications, formulations or combination therapies being explored for capsaicin. While the analgesic pharmacopeia for chronic pain patients is ancient and poorly effective, modern TRPV1-targeted drugs could rapidly become available as the next generation of analgesics for a broad spectrum of pain conditions.
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Affiliation(s)
- Mircea Iftinca
- Department of Physiology and Pharmacology, Inflammation Research Network-Snyder Institute for Chronic Diseases and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta, T2N 4N1, Canada
| | - Manon Defaye
- Department of Physiology and Pharmacology, Inflammation Research Network-Snyder Institute for Chronic Diseases and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta, T2N 4N1, Canada
| | - Christophe Altier
- Department of Physiology and Pharmacology, Inflammation Research Network-Snyder Institute for Chronic Diseases and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta, T2N 4N1, Canada.
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12
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Zhang B, Ma S, Rachmin I, He M, Baral P, Choi S, Gonçalves WA, Shwartz Y, Fast EM, Su Y, Zon LI, Regev A, Buenrostro JD, Cunha TM, Chiu IM, Fisher DE, Hsu YC. Hyperactivation of sympathetic nerves drives depletion of melanocyte stem cells. Nature 2020; 577:676-681. [PMID: 31969699 PMCID: PMC7184936 DOI: 10.1038/s41586-020-1935-3] [Citation(s) in RCA: 149] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 12/13/2019] [Indexed: 01/24/2023]
Abstract
Empirical and anecdotal evidence have associated stress with accelerated hair greying (formation of unpigmented hairs)1,2, but the scientific evidence linking the two is scant. Here, we report that acute stress leads to hair greying through fast depletion of melanocyte stem cells (MeSCs). Combining adrenalectomy, denervation, chemogenetics3,4, cell ablation, and MeSC-specific adrenergic receptor knockout, we found that stress-induced MeSC loss is independent of immune attack or adrenal stress hormones. Rather, hair greying results from activation of the sympathetic nerves that innervate the MeSC niche. Upon stress, sympathetic nerve activation leads to burst release of the neurotransmitter norepinephrine, which drives quiescent MeSCs into rapid proliferation, followed by differentiation, migration, and permanent depletion from the niche. Transient suppression of MeSC proliferation prevents stress-induced hair greying. Our studies demonstrate that acute stress-induced neuronal activity can drive rapid and permanent loss of somatic stem cells, and illustrate an example in which somatic stem cell maintenance is directly influenced by the overall physiological state of the organism.
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Affiliation(s)
- Bing Zhang
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA
| | - Sai Ma
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA.,Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Department of Biology and Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Inbal Rachmin
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Megan He
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA.,Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Pankaj Baral
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Sekyu Choi
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA
| | - William A Gonçalves
- Institute of Biological Science, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Yulia Shwartz
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA
| | - Eva M Fast
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA.,Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Yiqun Su
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Leonard I Zon
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA.,Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital and Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Aviv Regev
- Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Department of Biology and Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Jason D Buenrostro
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA
| | - Thiago M Cunha
- Department of Immunology, Harvard Medical School, Boston, MA, USA.,Center for Research in Inflammatory Diseases (CRID), Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Isaac M Chiu
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - David E Fisher
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Ya-Chieh Hsu
- Department of Stem Cell and Regenerative Biology, Harvard University and Harvard Stem Cell Institute, Cambridge, MA, USA.
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Shomorony A, Santamaria CM, Zhao C, Rwei AY, Mehta M, Zurakowski D, Kohane DS. Prolonged Duration Local Anesthesia by Combined Delivery of Capsaicin- and Tetrodotoxin-Loaded Liposomes. Anesth Analg 2019; 129:709-717. [PMID: 31425210 DOI: 10.1213/ane.0000000000004108] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Capsaicin, the active component of chili peppers, can produce sensory-selective peripheral nerve blockade. Coadministration of capsaicin and tetrodotoxin, a site-1 sodium channel blocker, can achieve a synergistic effect on duration of nerve blocks. However, capsaicin can be neurotoxic, and tetrodotoxin can cause systemic toxicity. We evaluated whether codelivery of capsaicin and tetrodotoxin liposomes can achieve prolonged local anesthesia without local or systemic toxicity. METHODS Capsaicin- and tetrodotoxin-loaded liposomes were developed. Male Sprague-Dawley rats were injected at the sciatic nerve with free capsaicin, capsaicin liposomes, free tetrodotoxin, tetrodotoxin liposomes, and blank liposomes, singly or in combination. Sensory and motor nerve blocks were assessed by a modified hotplate test and a weight-bearing test, respectively. Local toxicity was assessed by histologic scoring of tissues at the injection sites and transmission electron microscopic examination of the sciatic nerves. Systemic toxicity was assessed by rates of contralateral nerve deficits and/or mortality. RESULTS The combination of capsaicin liposomes and tetrodotoxin liposomes achieved a mean duration of sensory block of 18.2 hours (3.8 hours) [mean (SD)], far longer than that from capsaicin liposomes [0.4 hours (0.5 hours)] (P < .001) or tetrodotoxin liposomes [0.4 hours (0.7 hours)] (P < .001) given separately with or without the second drug in free solution. This combination caused minimal myotoxicity and muscle inflammation, and there were no changes in the percentage or diameter of unmyelinated axons. There was no systemic toxicity. CONCLUSIONS The combination of encapsulated tetrodotoxin and capsaicin achieved marked prolongation of nerve block. This combination did not cause detectable local or systemic toxicity. Capsaicin may be useful for its synergistic effects on other formulations even when used in very small, safe quantities.
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Affiliation(s)
- Andre Shomorony
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Claudia M Santamaria
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Chao Zhao
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Alina Y Rwei
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Manisha Mehta
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - David Zurakowski
- Department of Anesthesiology, Perioperative, and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Daniel S Kohane
- From the Laboratory for Biomaterials and Drug Delivery, Division of Critical Care Medicine, Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
- Department of Anesthesiology, Perioperative, and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
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Gouveia DN, Guimarães AG, Santos WBDR, Quintans-Júnior LJ. Natural products as a perspective for cancer pain management: A systematic review. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2019; 58:152766. [PMID: 31005719 DOI: 10.1016/j.phymed.2018.11.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/14/2018] [Accepted: 11/17/2018] [Indexed: 06/09/2023]
Abstract
BACKGROUND Cancer is the leading cause of death in the world and one of the main symptoms affecting these individuals is chronic pain, which must be evaluated and treated in its various components. Several drugs are currently used, but beyond the high cost, they have harmful side effects to patients or are transitorily effective. Ergo, there is a need to look for new options for cancer pain relief. Natural products (NPs) present themselves as strong candidates for the development of new drugs for the treatment of chronic pain, such as cancer pain. PURPOSE This systematic review aimed to summarize current knowledge about the analgesic profile of NPs in cancer pain. METHODS The search included PubMed, Scopus and Web of Science (from inception to June 2018) sought to summarize the articles studying new proposals with NPs for the management of oncological pain. Two independent reviewers extracted data on study characteristics, methods and outcomes. RESULTS After an extensive survey, 21 articles were selected, which described the analgesic potential of 15 natural compounds to relieve cancer pain. After analyzing the data, it can be suggested that these NPs, which have targets in central and peripheral mechanisms, are interesting candidates for the treatment of cancer pain for addressing different pharmacological mechanisms (even innovative), but ensuring the safety of these compounds is still a challenge. Likewise, the cannabinoids compounds leave the front as the most promising compounds for direct applicability due to the clinical studies that have already been developed and the background already established about these effects on chronic pain. CONCLUSION Regarding these findings, it can be concluded that the variability of possible biological sites of action is strategic for new perspectives in the development of therapeutic proposals different from those available in the current market.
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Affiliation(s)
- Daniele Nascimento Gouveia
- Departamento de Fisiologia, Laboratório de Neurociências e Ensaios Farmacológicos (LANEF). Universidade Federal de Sergipe, São Cristovão, Sergipe, Brazil
| | - Adriana Gibara Guimarães
- Departamento de Educação em Saúde, Universidade Federal de Sergipe, Av. Governador Marcelo Déda, 13, Lagarto, Sergipe, Brazil.
| | - Wagner Barbosa da Rocha Santos
- Departamento de Fisiologia, Laboratório de Neurociências e Ensaios Farmacológicos (LANEF). Universidade Federal de Sergipe, São Cristovão, Sergipe, Brazil
| | - Lucindo José Quintans-Júnior
- Departamento de Fisiologia, Laboratório de Neurociências e Ensaios Farmacológicos (LANEF). Universidade Federal de Sergipe, São Cristovão, Sergipe, Brazil
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15
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Long-term pain relief in canine osteoarthritis by a single intra-articular injection of resiniferatoxin, a potent TRPV1 agonist. Pain 2019; 159:2105-2114. [PMID: 30015705 DOI: 10.1097/j.pain.0000000000001314] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The translational potential of analgesic approaches emerging from basic research can be augmented by client-owned dog trials. We report on a peripheral interventional approach that uses intra-articular injection of the ultrapotent TRPV1 agonist resiniferatoxin (RTX) to produce a selective long-term chemoinactivation of nociceptive primary afferent nerve endings for pain control in naturally occurring canine osteoarthritis. A single injection of 10 µg of RTX, produced suppression of pain, improvement in gait, weight bearing, and improvement in the dog's activities of daily living lasting 4 months or longer. Two to 3 years after the injection, there are no alterations to suggest that removal of inflammatory pain caused accelerated joint degeneration (Charcot joint) in any of the dogs. To amplify the effective use of canine subjects in translational analgesia research, we report a high-quality canine dorsal root ganglion transcriptome. Some targets for analgesia are highly conserved both in protein sequence and level of expression within a target tissue while others diverge substantially from the human. This knowledge is especially important for development of analgesics aimed at peripheral molecular targets and provides a template for informed translational research. The peripheral site of action, long duration of analgesia, apparent safety, and retention of coordination, all resulting from a single dose suggest that intra-articular RTX may be an effective intervention for osteoarthritis pain with few or no side effects and lead to an improved quality of life.
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16
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Liu X, Yan D, Guo SW. Sensory nerve-derived neuropeptides accelerate the development and fibrogenesis of endometriosis. Hum Reprod 2019; 34:452-468. [PMID: 30689856 DOI: 10.1093/humrep/dey392] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/04/2018] [Accepted: 12/14/2018] [Indexed: 12/16/2022] Open
Affiliation(s)
- Xishi Liu
- Shanghai OB/GYN Hospital, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Female Reproductive Endocrine-Related Diseases, Fudan University, Shanghai, China
| | - Dingmin Yan
- Shanghai OB/GYN Hospital, Fudan University, Shanghai, China
| | - Sun-Wei Guo
- Shanghai OB/GYN Hospital, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Female Reproductive Endocrine-Related Diseases, Fudan University, Shanghai, China
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17
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Salas MM, Clifford JL, Hayden JR, Iadarola MJ, Averitt DL. Local Resiniferatoxin Induces Long-Lasting Analgesia in a Rat Model of Full Thickness Thermal Injury. PAIN MEDICINE 2018; 18:2453-2465. [PMID: 27794548 DOI: 10.1093/pm/pnw260] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective Opioid-based analgesics are a major component of the lengthy pain management of burn patients, including military service members, but are problematic due to central nervous system-mediated side effects. Peripheral analgesia via targeted ablation of nociceptive nerve endings that express the transient receptor potential vanilloid channel 1 (TRPV1) may provide an improved approach. We hypothesized that local injection of the TRPV1 agonist resiniferatoxin (RTX) would produce long-lasting analgesia in a rat model of pain associated with burn injury. Methods Baseline sensitivities to thermal and mechanical stimuli were measured in male and female Sprague-Dawley rats. Under anesthesia, a 100 °C metal probe was placed on the right hind paw for 30 seconds, and sensitivity was reassessed 72 hours following injury. Rats received RTX (0.25 μg/100 μL; ipl) into the injured hind paw, and sensitivity was reassessed across three weeks. Tissues were collected from a separate group of rats at 24 hours and/or one week post-RTX for pathological analyses of the injured hind paw, dorsal spinal cord c-Fos, and primary afferent neuropeptide immunoreactivity. Results Local RTX reversed burn pain behaviors within 24 hours, which lasted through recovery at three weeks. At one week following RTX, decreased c-Fos and primary afferent neuropeptide immunoreactivities were observed in the dorsal horn, while plantar burn pathology was unaltered. Conclusions These results indicate that local RTX induces long-lasting analgesia in a rat model of pain associated with burn. While opioids are undesirable in trauma patients due to side effects, RTX may provide valuable long-term, nonopioid analgesia for burn patients.
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Affiliation(s)
- Margaux M Salas
- Pain Management Research Area, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - John L Clifford
- Pain Management Research Area, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Jessica R Hayden
- Pain Management Research Area, United States Army Institute of Surgical Research, JBSA Fort Sam Houston, Texas
| | - Michael J Iadarola
- Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Dayna L Averitt
- Department of Biology, Texas Woman's University, Denton, Texas, USA
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18
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Raithel SJ, Sapio MR, LaPaglia DM, Iadarola MJ, Mannes AJ. Transcriptional Changes in Dorsal Spinal Cord Persist after Surgical Incision Despite Preemptive Analgesia with Peripheral Resiniferatoxin. Anesthesiology 2018; 128:620-635. [PMID: 29271803 PMCID: PMC11175836 DOI: 10.1097/aln.0000000000002006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Peripheral nociceptors expressing the ion channel transient receptor potential cation channel, subfamily V, member 1, play an important role in mediating postoperative pain. Signaling from these nociceptors in the peri- and postoperative period can lead to plastic changes in the spinal cord and, when controlled, can yield analgesia. The transcriptomic changes in the dorsal spinal cord after surgery, and potential coupling to transient receptor potential cation channel, subfamily V, member 1-positive nociceptor signaling, remain poorly studied. METHODS Resiniferatoxin was injected subcutaneously into rat hind paw several minutes before surgical incision to inactivate transient receptor potential cation channel, subfamily V, member 1-positive nerve terminals. The effects of resiniferatoxin on postincisional measures of pain were assessed through postoperative day 10 (n = 51). Transcriptomic changes in the dorsal spinal cord, with and without peripheral transient receptor potential cation channel, subfamily V, member 1-positive nerve terminal inactivation, were assessed by RNA sequencing (n = 22). RESULTS Peripherally administered resiniferatoxin increased thermal withdrawal latency by at least twofold through postoperative day 4, increased mechanical withdrawal threshold by at least sevenfold through postoperative day 2, and decreased guarding score by 90% relative to vehicle control (P < 0.05). Surgical incision induced 70 genes in the dorsal horn, and these changes were specific to the ipsilateral dorsal horn. Gene induction with surgical incision persisted despite robust analgesia from resiniferatoxin pretreatment. Many of the genes induced were related to microglial activation, such as Cd11b and Iba1. CONCLUSIONS A single subcutaneous injection of resiniferatoxin before incision attenuated both evoked and nonevoked measures of postoperative pain. Surgical incision induced transcriptomic changes in the dorsal horn that persisted despite analgesia with resiniferatoxin, suggesting that postsurgical pain signals can be blocked without preventing transcription changes in the dorsal horn.
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Affiliation(s)
- Stephen J Raithel
- From the Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland (S.J.R., M.R.S., D.M.L., M.J.I., A.J.M.); and the Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio (S.J.R.)
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Lee YC, Lu SC, Hsieh YL. Establishing a Mouse Model of a Pure Small Fiber Neuropathy with the Ultrapotent Agonist of Transient Receptor Potential Vanilloid Type 1. J Vis Exp 2018. [PMID: 29553496 DOI: 10.3791/56651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Patients with diabetes mellitus (DM) or those experiencing the neurotoxic effects of chemotherapeutic agents may develop sensation disorders due to degeneration and injury of small-diameter sensory neurons, referred to as small fiber neuropathy. Present animal models of small fiber neuropathy affect both large- and small-diameter sensory fibers and thus create a neuropathology too complex to properly assess the effects of injured small-diameter sensory fibers. Therefore, it is necessary to develop an experimental model of pure small fiber neuropathy to adequately examine these issues. This protocol describes an experimental model of small fiber neuropathy specifically affecting small-diameter sensory nerves with resiniferatoxin (RTX), an ultrapotent agonist of transient receptor potential vanilloid type 1 (TRPV1), through a single dose of intraperitoneal injection, referred to as RTX neuropathy. This RTX neuropathy showed pathological manifestations and behavioral abnormalities that mimic the clinical characteristics of patients with small fiber neuropathy, including intraepidermal nerve fiber (IENF) degeneration, specifically injury in small-diameter neurons, and induction of thermal hypoalgesia and mechanical allodynia. This protocol tested three doses of RTX (200, 50, and 10 µg/kg, respectively) and concluded that a critical dose of RTX (50 µg/kg) is required for the development of typical small fiber neuropathy manifestations, and prepared a modified immunostaining procedure to investigate IENF degeneration and neuronal soma injury. The modified procedure is fast, systematic, and economic. Behavioral evaluation of neuropathic pain is critical to reveal the function of small-diameter sensory nerves. The evaluation of mechanical thresholds in experimental rodents is particularly challenging and this protocol describes a customized metal mesh that is suitable for this type of assessment in rodents. In summary, RTX neuropathy is a new and easily established experimental model to evaluate the molecular significance and intervention underlying neuropathic pain for the development of therapeutic agents.
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Affiliation(s)
- Yi-Chen Lee
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University; Department of Medical Research, Kaohsiung Medical University Hospital
| | - Shui-Chin Lu
- Department of Medical Research, Ultrastructural Laboratory, Kaohsiung Medical University Hospital
| | - Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University; Department of Medical Research, Kaohsiung Medical University Hospital;
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20
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Souza RFD, Oliveira LLD, Nones CFM, dos Reis RC, Araya EI, Kopruszinski CM, Rae GA, Chichorro JG. Mechanisms involved in facial heat hyperalgesia induced by endothelin-1 in female rats. Arch Oral Biol 2017; 83:297-303. [DOI: 10.1016/j.archoralbio.2017.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 08/17/2017] [Accepted: 08/27/2017] [Indexed: 01/29/2023]
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21
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Minimally invasive probes for programmed microfluidic delivery of molecules in vivo. Curr Opin Pharmacol 2017; 36:78-85. [PMID: 28892801 DOI: 10.1016/j.coph.2017.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 08/19/2017] [Accepted: 08/21/2017] [Indexed: 01/06/2023]
Abstract
Site-specific drug delivery carries many advantages of systemic administration, but is rarely used in the clinic. One limiting factor is the relative invasiveness of the technology to locally deliver compounds. Recent advances in materials science and electrical engineering allow for the development of ultraminiaturized microfluidic channels based on soft materials to create flexible probes capable of deep tissue targeting. A diverse set of mechanics, including micro-pumps and functional materials, used to deliver the drugs can be paired with wireless electronics for self-contained and programmable operation. These first iterations of minimally invasive fluid delivery devices foreshadow important advances needed for clinical translation.
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22
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Pecze L, Viskolcz B, Oláh Z. Molecular Surgery Concept from Bench to Bedside: A Focus on TRPV1+ Pain-Sensing Neurons. Front Physiol 2017. [PMID: 28626428 PMCID: PMC5455100 DOI: 10.3389/fphys.2017.00378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
"Molecular neurosurgery" is emerging as a new medical concept, and is the combination of two partners: (i) a molecular neurosurgery agent, and (ii) the cognate receptor whose activation results in the selective elimination of a specific subset of neurons in which this receptor is endogenously expressed. In general, a molecular surgery agent is a selective and potent ligand, and the target is a specific cell type whose elimination is desired through the molecular surgery procedure. These target cells have the highest innate sensitivity to the molecular surgery agent usually due to the highest receptor density being in their plasma membrane. The interaction between the ligand and its receptor evokes an overactivity of the receptor. If the receptor is a ligand-activated non-selective cation channel, the overactivity of receptor leads to excess Ca2+ and Na+ influx into the cell and finally cell death. One of the best known examples of such an interaction is the effect of ultrapotent vanilloids on TRPV1-expressing pain-sensing neurons. One intrathecal resiniferatoxin (RTX) dose allows for the receptor-mediated removal of TRPV1+ neurons from the peripheral nervous system. The TRPV1 receptor-mediated ion influx induces necrotic processes, but only in pain-sensing neurons, and usually within an hour. Besides that, target-specific apoptotic processes are also induced. Thus, as a nano-surgery scalpel, RTX removes the neurons responsible for generating pain and inflammation from the peripheral nervous system providing an option in clinical management for the treatment of morphine-insensitive pain conditions. In the future, the molecular surgery concept can also be exploited in cancer research for selectively targeting the specific tumor cell.
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Affiliation(s)
- László Pecze
- Unit of Anatomy, Department of Medicine, University of FribourgFribourg, Switzerland
| | - Béla Viskolcz
- Institute of Chemistry, Faculty of Materials Science and Engineering, University of MiskolcMiskolc, Hungary
| | - Zoltán Oláh
- Institute of Chemistry, Faculty of Materials Science and Engineering, University of MiskolcMiskolc, Hungary.,Acheuron Ltd.Szeged, Hungary
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Wang S, Wang S, Asgar J, Joseph J, Ro JY, Wei F, Campbell JN, Chung MK. Ca 2+ and calpain mediate capsaicin-induced ablation of axonal terminals expressing transient receptor potential vanilloid 1. J Biol Chem 2017; 292:8291-8303. [PMID: 28360106 DOI: 10.1074/jbc.m117.778290] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/28/2017] [Indexed: 01/01/2023] Open
Abstract
Capsaicin is an ingredient in spicy peppers that produces burning pain by activating transient receptor potential vanilloid 1 (TRPV1), a Ca2+-permeable ion channel in nociceptors. Capsaicin has also been used as an analgesic, and its topical administration is approved for the treatment of certain pain conditions. The mechanisms underlying capsaicin-induced analgesia likely involve reversible ablation of nociceptor terminals. However, the mechanisms underlying these effects are not well understood. To visualize TRPV1-lineage axons, a genetically engineered mouse model was used in which a fluorophore is expressed under the TRPV1 promoter. Using a combination of these TRPV1-lineage reporter mice and primary afferent cultures, we monitored capsaicin-induced effects on afferent terminals in real time. We found that Ca2+ influx through TRPV1 is necessary for capsaicin-induced ablation of nociceptive terminals. Although capsaicin-induced mitochondrial Ca2+ uptake was TRPV1-dependent, dissipation of the mitochondrial membrane potential, inhibition of the mitochondrial transition permeability pore, and scavengers of reactive oxygen species did not attenuate capsaicin-induced ablation. In contrast, MDL28170, an inhibitor of the Ca2+-dependent protease calpain, diminished ablation. Furthermore, overexpression of calpastatin, an endogenous inhibitor of calpain, or knockdown of calpain 2 also decreased ablation. Quantitative assessment of TRPV1-lineage afferents in the epidermis of the hind paws of the reporter mice showed that EGTA and MDL28170 diminished capsaicin-induced ablation. Moreover, MDL28170 prevented capsaicin-induced thermal hypoalgesia. These results suggest that TRPV1/Ca2+/calpain-dependent signaling plays a dominant role in capsaicin-induced ablation of nociceptive terminals and further our understanding of the molecular mechanisms underlying the effects of capsaicin on nociceptors.
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Affiliation(s)
- Sheng Wang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | - Sen Wang
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | - Jamila Asgar
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | - John Joseph
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | - Jin Y Ro
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | - Feng Wei
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201
| | | | - Man-Kyo Chung
- Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland 21201.
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Parisi JR, de Andrade ALM, Torres Silva JR, Silva ML. Antiallodynic effect of intrathecal resiniferatoxin on neuropathic pain model of chronic constriction injury. Acta Neurobiol Exp (Wars) 2017. [DOI: 10.21307/ane-2017-064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Chung MK, Campbell JN. Use of Capsaicin to Treat Pain: Mechanistic and Therapeutic Considerations. Pharmaceuticals (Basel) 2016; 9:ph9040066. [PMID: 27809268 PMCID: PMC5198041 DOI: 10.3390/ph9040066] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 12/31/2022] Open
Abstract
Capsaicin is the pungent ingredient of chili peppers and is approved as a topical treatment of neuropathic pain. The analgesia lasts for several months after a single treatment. Capsaicin selectively activates TRPV1, a Ca2+-permeable cationic ion channel that is enriched in the terminals of certain nociceptors. Activation is followed by a prolonged decreased response to noxious stimuli. Interest also exists in the use of injectable capsaicin as a treatment for focal pain conditions, such as arthritis and other musculoskeletal conditions. Recently injection of capsaicin showed therapeutic efficacy in patients with Morton’s neuroma, a painful foot condition associated with compression of one of the digital nerves. The relief of pain was associated with no change in tactile sensibility. Though injection evokes short term pain, the brief systemic exposure and potential to establish long term analgesia without other sensory changes creates an attractive clinical profile. Short-term and long-term effects arise from both functional and structural changes in nociceptive terminals. In this review, we discuss how local administration of capsaicin may induce ablation of nociceptive terminals and the clinical implications.
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Affiliation(s)
- Man-Kyo Chung
- Department of Neural and Pain Sciences, University of Maryland, School of Dentistry, Program in Neuroscience, Center to Advance Chronic Pain Research, Baltimore, MD 21201, USA.
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Campbell BK, Fillingim RB, Lee S, Brao R, Price DD, Neubert JK. Effects of High-Dose Capsaicin on TMD Subjects: A Randomized Clinical Study. JDR Clin Trans Res 2016; 2:58-65. [PMID: 28879245 DOI: 10.1177/2380084416675837] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Temporomandibular joint disorder (TMD) is a complex musculoskeletal disorder that presents with pain, limited jaw opening, and abnormal noises in the temporomandibular joint. Despite the significant impact that TMD has in terms of suffering and financial burden, relatively few new treatments have emerged; therefore, development of novel treatments to treat TMD pain remains a high priority. The rationale of this study was to use a double-blind, vehicle-controlled clinical trial to evaluate the effects of a high-concentration (8%) capsaicin cream on TMD. This is based on the hypothesis that targeting TRP vanilloid subfamily member 1 (TRPV1) for pain control may provide a novel method for pain relief in TMD patients. TRPV1 is primarily expressed on a population of nociceptive-specific neurons and provides a candidate target for the development of pain treatments. Capsaicin is the primary agonist for TRPV1 and has been used previously in relatively low doses (0.025% to 0.075%) as a therapeutic for a variety of pain disorders, including postherpetic neuralgia and osteoarthritis; however, analgesic efficacy remains equivocal. TMD and healthy control subjects were assigned to either an active capsaicin or vehicle control group. The treatments were applied for 2 h and then removed. Quantitative sensory testing (QST) was completed prior to drug application (baseline), 2 h after drug application, and 1 wk later. Perceived pain intensity was measured using a visual analog scale (VAS) following capsaicin or vehicle cream application. Significantly lower pain was reported in the week after application in the capsaicin-treated TMD subjects. For QST measures, there was a decreased thermal pain threshold 2 h after capsaicin application for both the control and TMD groups, but this resolved within a week. Capsaicin had no effect on pressure pain threshold or mechanical sensitivity in both TMD and healthy individuals. This study demonstrates that 8% topical capsaicin therapy is a relatively safe, simple, and effective treatment for patients with TMD. Knowledge Transfer Statement: This study evaluated a novel topical capsaicin therapy for reducing orofacial pain. The results of this study can be used to provide another treatment option for patients with TMD.
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Affiliation(s)
| | - R B Fillingim
- Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - S Lee
- Department of Orthodontics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea
| | - R Brao
- Department of Orthodontics, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - D D Price
- Department of Oral Surgery and Diagnostic Sciences, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - J K Neubert
- Department of Orthodontics, College of Dentistry, University of Florida, Gainesville, FL, USA
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Brown JD, Saeed M, Do L, Braz J, Basbaum AI, Iadarola MJ, Wilson DM, Dillon WP. CT-guided injection of a TRPV1 agonist around dorsal root ganglia decreases pain transmission in swine. Sci Transl Med 2016; 7:305ra145. [PMID: 26378245 DOI: 10.1126/scitranslmed.aac6589] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
One approach to analgesia is to block pain at the site of origin or along the peripheral pathway by selectively ablating pain-transmitting neurons or nerve terminals directly. The heat/capsaicin receptor (TRPV1) expressed by nociceptive neurons is a compelling target for selective interventional analgesia because it leaves somatosensory and proprioceptive neurons intact. Resiniferatoxin (RTX), like capsaicin, is a TRPV1 agonist but has greater potency. We combine RTX-mediated inactivation with the precision of computed tomography (CT)-guided delivery to ablate peripheral pain fibers in swine. Under CT guidance, RTX was delivered unilaterally around the lumbar dorsal root ganglia (DRG), and vehicle only was administered to the contralateral side. During a 4-week observation period, animals demonstrated delayed or absent withdrawal responses to infrared laser heat stimuli delivered to sensory dermatomes corresponding to DRG receiving RTX treatment. Motor function was unimpaired as assessed by disability scoring and gait analysis. In treated DRG, TRPV1 mRNA expression was reduced, as were nociceptive neuronal perikarya in ganglia and their nerve terminals in the ipsilateral dorsal horn. CT guidance to precisely deliver RTX to sites of peripheral pain transmission in swine may be an approach that could be tailored to block an array of clinical pain conditions in patients.
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Affiliation(s)
- Jacob D Brown
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94117, USA
| | - Maythem Saeed
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94117, USA
| | - Loi Do
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94117, USA
| | - Joao Braz
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94117, USA
| | - Allan I Basbaum
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94117, USA
| | - Michael J Iadarola
- Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - David M Wilson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94117, USA
| | - William P Dillon
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA 94117, USA.
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Pecze L, Jósvay K, Blum W, Petrovics G, Vizler C, Oláh Z, Schwaller B. Activation of endogenous TRPV1 fails to induce overstimulation-based cytotoxicity in breast and prostate cancer cells but not in pain-sensing neurons. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2054-64. [PMID: 27180305 DOI: 10.1016/j.bbamcr.2016.05.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/30/2016] [Accepted: 05/09/2016] [Indexed: 01/21/2023]
Abstract
Vanilloids including capsaicin and resiniferatoxin are potent transient receptor potential vanilloid type 1 (TRPV1) agonists. TRPV1 overstimulation selectively ablates capsaicin-sensitive sensory neurons in animal models in vivo. The cytotoxic mechanisms are based on strong Na(+) and Ca(2+) influx via TRPV1 channels, which leads to mitochondrial Ca(2+) accumulation and necrotic cell swelling. Increased TRPV1 expression levels are also observed in breast and prostate cancer and derived cell lines. Here, we examined whether potent agonist-induced overstimulation mediated by TRPV1 might represent a means for the eradication of prostate carcinoma (PC-3, Du 145, LNCaP) and breast cancer (MCF7, MDA-MB-231, BT-474) cells in vitro. While rat sensory neurons were highly vanilloid-sensitive, normal rat prostate epithelial cells were resistant in vivo. We found TRPV1 to be expressed in all cancer cell lines at mRNA and protein levels, yet protein expression levels were significantly lower compared to sensory neurons. Treatment of all human carcinoma cell lines with capsaicin didn't lead to overstimulation cytotoxicity in vitro. We assume that the low vanilloid-sensitivity of prostate and breast cancer cells is associated with low expression levels of TRPV1, since ectopic TRPV1 expression rendered them susceptible to the cytotoxic effect of vanilloids evidenced by plateau-type Ca(2+) signals, mitochondrial Ca(2+) accumulation and Na(+)- and Ca(2+)-dependent membrane disorganization. Moreover, long-term monitoring revealed that merely the ectopic expression of TRPV1 stopped cell proliferation and often induced apoptotic processes via strong activation of caspase-3 activity. Our results indicate that specific targeting of TRPV1 function remains a putative strategy for cancer treatment.
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Affiliation(s)
- László Pecze
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, Fribourg CH-1700, Switzerland.
| | - Katalin Jósvay
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6701, Hungary
| | - Walter Blum
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, Fribourg CH-1700, Switzerland
| | - György Petrovics
- Department of Surgery, Center for Prostate Disease Research, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Csaba Vizler
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged H-6701, Hungary
| | - Zoltán Oláh
- Acheuron Hungary Ltd., Szeged H-6726, Hungary (e) Institute of Chemistry, Faculty of Material Science and Engineering, University of Miskolc, H-3515, Hungary; Institute of Chemistry, Faculty of Material Science and Engineering, University of Miskolc, H-3515, Hungary
| | - Beat Schwaller
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, Fribourg CH-1700, Switzerland
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Intraganglionar resiniferatoxin prevents orofacial inflammatory and neuropathic hyperalgesia. Behav Pharmacol 2014; 25:112-8. [PMID: 24557321 DOI: 10.1097/fbp.0000000000000024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Trigeminal ganglion C-fiber neurons bearing transient receptor potential vanilloid-1 (TRPV1) channels are selectively destroyed by resiniferatoxin (RTX), a potent capsaicin analogue. The current study assessed the effect of an RTX injection (200 ng/4 μl) into the trigeminal ganglion in inflammatory and neuropathic rat models of orofacial thermal hyperalgesia. Intraganglionar RTX injection resulted in trigeminal ganglion C-fiber deletion, which was confirmed by the capsaicin eye wipes test, performed 6 days after the injection. The nociceptive responses induced by 2.5% formalin injected into the orofacial region were unchanged by a previous intraganglionar RTX injection. However, orofacial heat and cold hyperalgesia, induced by carrageenan injected into the upper lip (50 µg/50 μl), was abolished by previous intraganglionar RTX treatment. In addition, the development of orofacial heat and cold hyperalgesia after constriction of the infraorbital nerve was prevented by previous RTX treatment. Thus, trigeminal ganglion neurons expressing TRPV1 are crucial for the development of orofacial inflammatory and neuropathic thermal hyperalgesia.
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Goswami SC, Mishra SK, Maric D, Kaszas K, Gonnella GL, Clokie SJ, Kominsky HD, Gross JR, Keller JM, Mannes AJ, Hoon MA, Iadarola MJ. Molecular signatures of mouse TRPV1-lineage neurons revealed by RNA-Seq transcriptome analysis. THE JOURNAL OF PAIN 2014; 15:1338-1359. [PMID: 25281809 DOI: 10.1016/j.jpain.2014.09.010] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 09/10/2014] [Accepted: 09/19/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED Disorders of pain neural systems are frequently chronic and, when recalcitrant to treatment, can severely degrade the quality of life. The pain pathway begins with sensory neurons in dorsal root or trigeminal ganglia, and the neuronal subpopulations that express the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) ion channel transduce sensations of painful heat and inflammation and play a fundamental role in clinical pain arising from cancer and arthritis. In the present study, we elucidate the complete transcriptomes of neurons from the TRPV1 lineage and a non-TRPV1 neuroglial population in sensory ganglia through the combined application of next-gen deep RNA-Seq, genetic neuronal labeling with fluorescence-activated cell sorting, or neuron-selective chemoablation. RNA-Seq accurately quantitates gene expression, a difficult parameter to determine with most other methods, especially for very low and very high expressed genes. Differentially expressed genes are present at every level of cellular function from the nucleus to the plasma membrane. We identified many ligand receptor pairs in the TRPV1 population, suggesting that autonomous presynaptic regulation may be a major regulatory mechanism in nociceptive neurons. The data define, in a quantitative, cell population-specific fashion, the molecular signature of a distinct and clinically important group of pain-sensing neurons and provide an overall framework for understanding the transcriptome of TRPV1 nociceptive neurons. PERSPECTIVE Next-gen RNA-Seq, combined with molecular genetics, provides a comprehensive and quantitative measurement of transcripts in TRPV1 lineage neurons and a contrasting transcriptome from non-TRPV1 neurons and cells. The transcriptome highlights previously unrecognized protein families, identifies multiple molecular circuits for excitatory or inhibitory autocrine and paracrine signaling, and suggests new combinatorial approaches to pain control.
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Affiliation(s)
- Samridhi C Goswami
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Santosh K Mishra
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Dragan Maric
- Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Krisztian Kaszas
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Gian Luigi Gonnella
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Samuel J Clokie
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Hal D Kominsky
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jacklyn R Gross
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jason M Keller
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andrew J Mannes
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mark A Hoon
- Molecular Genetics Unit, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Michael J Iadarola
- Anesthesia Section, Department of Perioperative Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland.
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Danigo A, Magy L, Richard L, Sturtz F, Funalot B, Demiot C. A reversible functional sensory neuropathy model. Neurosci Lett 2014; 571:39-44. [PMID: 24792390 DOI: 10.1016/j.neulet.2014.04.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 04/07/2014] [Accepted: 04/19/2014] [Indexed: 11/26/2022]
Abstract
Small-fiber neuropathy was induced in young adult mice by intraperitoneal injection of resiniferatoxin (RTX), a TRPV1 agonist. At day 7, RTX induced significant thermal and mechanical hypoalgesia. At day 28, mechanical and thermal nociception were restored. No nerve degeneration in skin was observed and unmyelinated nerve fiber morphology and density in sciatic nerve were unchanged. At day 7, substance P (SP) was largely depleted in dorsal root ganglia (DRG) neurons, although calcitonin gene-related peptide (CGRP) was only moderately depleted. Three weeks after, SP and CGRP expression was restored in DRG neurons. At the same time, CGRP expression remained low in intraepidermal nerve fibers (IENFs) whereas SP expression had improved. In summary, RTX induced in our model a transient neuropeptide depletion in sensory neurons without nerve degeneration. We think this model is valuable as it brings the opportunity to study functional nerve changes in the very early phase of small fiber neuropathy. Moreover, it may represent a useful tool to study the mechanisms of action of therapeutic strategies to prevent sensory neuropathy of various origins.
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Affiliation(s)
- Aurore Danigo
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France
| | - Laurent Magy
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France; Service de Neurologie, Centre de référence national "neuropathies périphériques rares" - CHU Limoges, 87042 Limoges Cedex, France
| | - Laurence Richard
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France; Service de Neurologie, Centre de référence national "neuropathies périphériques rares" - CHU Limoges, 87042 Limoges Cedex, France
| | - Franck Sturtz
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France
| | - Benoît Funalot
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France; Service de Neurologie, Centre de référence national "neuropathies périphériques rares" - CHU Limoges, 87042 Limoges Cedex, France
| | - Claire Demiot
- EA 6309 - Schools of Medicine and Pharmacy - University of Limoges, France.
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Hsiao TH, Fu YS, Ho WY, Chen TH, Hsieh YL. Promotion of thermal analgesia and neuropeptidergic skin reinnervation by 4-methylcatechol in resiniferatoxin-induced neuropathy. Kaohsiung J Med Sci 2013; 29:405-11. [DOI: 10.1016/j.kjms.2012.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 09/17/2012] [Indexed: 02/04/2023] Open
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Iadarola MJ, Gonnella GL. Resiniferatoxin for Pain Treatment: An Interventional Approach to Personalized Pain Medicine. ACTA ACUST UNITED AC 2013; 6:95-107. [PMID: 26779292 PMCID: PMC4711370 DOI: 10.2174/1876386301306010095] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This review examines existing preclinical and clinical studies related to resiniferatoxin (RTX) and its potential uses in pain treatment. Like capsaicin, RTX is a vanilloid receptor (TRPV1) agonist, only more potent. This increased potency confers both quantitative and qualitative advantages in terms of drug action on the TRPV1 containing nerve terminal, which result in an increased efficacy and a long duration of action. RTX can be delivered by a central route of administration through injection into the subarachnoid space around the lumbosacral spinal cord. It can also be administered peripherally into a region of skin or deep tissue where primary afferents nerves terminate, or directly into a nerve trunk or a dorsal root ganglion. The central route is currently being evaluated as a treatment for intractable pain in patients with advanced cancer. Peripheral administration offers the possibility to treat a wide diversity of pain problems because of the ability to bring the treatment to the site of the pain (the peripheral generator). While not all pain disorders are appropriate for RTX, tailoring treatment to an individual patient's needs via a selective and local intervention that chemically targets a specific population of nerve terminals provides a new capability for pain therapy and a simplified and effective approach to personalized pain medicine.
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Affiliation(s)
- Michael J Iadarola
- Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, NIH; Building 49 Room 1C20, 49 Convent Drive MSC 4410, Bethesda MD 20892-4410, USA
| | - Gian Luigi Gonnella
- Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, NIH; Department of Anesthesiology and Intensive Care Medicine, Catholic University School of Medicine, Rome, Italy
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Li C, Zhu Y, Shenoy M, Pai R, Liu L, Pasricha PJ. Anatomical and functional characterization of a duodeno-pancreatic neural reflex that can induce acute pancreatitis. Am J Physiol Gastrointest Liver Physiol 2013; 304:G490-500. [PMID: 23306082 PMCID: PMC3602681 DOI: 10.1152/ajpgi.00012.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neural cross talk between visceral organs may play a role in mediating inflammation and pain remote from the site of the insult. We hypothesized such a cross talk exists between the duodenum and pancreas, and further it induces pancreatitis in response to intraduodenal toxins. A dichotomous spinal innervation serving both the duodenum and pancreas was examined, and splanchnic nerve responses to mechanical stimulation of these organs were detected. This pathway was then excited on the duodenal side by exposure to ethanol followed by luminal mustard oil to activate transient receptor potential subfamily A, member 1 (TRPA1). Ninety minutes later, pancreatic inflammation was examined. Ablation of duodenal afferents by resiniferatoxin (RTX) or blocking TRPA1 by Chembridge (CHEM)-5861528 was used to further investigate the duodeno-pancreatic neural reflex via TRPA1. ~40% of dorsal root ganglia (DRG) from the spinal cord originated from both duodenum and pancreas via dichotomous peripheral branches; ~50% splanchnic nerve single units responded to mechanical stimulation of both organs. Ethanol sensitized TRPA1 currents in cultured DRG neurons. Pancreatic edema and myeloperoxidase activity significantly increased after intraduodenal ethanol followed by mustard oil (but not capsaicin) but significantly decreased after ablation of duodenal afferents by using RTX or blocking TRPA1 by CHEM-5861528. We found the existence of a neural cross talk between the duodenum and pancreas that can promote acute pancreatitis in response to intraduodenal chemicals. It also proves a previously unexamined mechanism by which alcohol can induce pancreatitis, which is novel both in terms of the site (duodenum), process (neurogenic), and receptor (TRPA1).
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Affiliation(s)
- Cuiping Li
- 1Division of Gastroenterology and Hepatology, Stanford University, Stanford, California; and
| | - Yaohui Zhu
- 1Division of Gastroenterology and Hepatology, Stanford University, Stanford, California; and
| | - Mohan Shenoy
- 1Division of Gastroenterology and Hepatology, Stanford University, Stanford, California; and
| | - Reetesh Pai
- 2Department of Pathology, Stanford University, Stanford, California
| | - Liansheng Liu
- 1Division of Gastroenterology and Hepatology, Stanford University, Stanford, California; and
| | - Pankaj Jay Pasricha
- 1Division of Gastroenterology and Hepatology, Stanford University, Stanford, California; and
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Hsieh YL, Lin CL, Chiang H, Fu YS, Lue JH, Hsieh ST. Role of peptidergic nerve terminals in the skin: reversal of thermal sensation by calcitonin gene-related peptide in TRPV1-depleted neuropathy. PLoS One 2012; 7:e50805. [PMID: 23209829 PMCID: PMC3507736 DOI: 10.1371/journal.pone.0050805] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Accepted: 10/23/2012] [Indexed: 11/18/2022] Open
Abstract
To investigate the contribution of peptidergic intraepidermal nerve fibers (IENFs) to nociceptive responses after depletion of the thermal-sensitive receptor, transient receptor potential vanilloid subtype 1 (TRPV1), we took advantage of a resiniferatoxin (RTX)-induced neuropathy which specifically affected small-diameter dorsal root ganglion (DRG) neurons and their corresponding nerve terminals in the skin. Thermal hypoalgesia (p<0.001) developed from RTX-treatment day 7 (RTXd7) and became normalized from RTXd56 to RTXd84. Substance P (SP)(+) and TRPV1(+) neurons were completely depleted (p = 0.0001 and p<0.0001, respectively), but RTX had a relatively minor effect on calcitonin gene-related peptide (CGRP)(+) neurons (p = 0.029). Accordingly, SP(+) (p<0.0001) and TRPV1(+) (p = 0.0008) IENFs were permanently depleted, but CGRP(+) IENFs (p = 0.012) were only transiently reduced and had recovered by RTXd84 (p = 0.83). The different effects of RTX on peptidergic neurons were attributed to the higher co-localization ratio of TRPV1/SP than of TRPV1/CGRP (p = 0.029). Thermal hypoalgesia (p = 0.0018) reappeared with an intraplantar injection of botulinum toxin type A (botox), and the temporal course of withdrawal latencies in the hot-plate test paralleled the innervation of CGRP(+) IENFs (p = 0.0003) and CGRP contents in skin (p = 0.01). In summary, this study demonstrated the preferential effects of RTX on depletion of SP(+) IENFs which caused thermal hypoalgesia. In contrast, the skin was reinnervated by CGRP(+) IENFs, which resulted in a normalization of nociceptive functions.
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Affiliation(s)
- Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Lung Lin
- Department of Neurosurgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- Faculty of Medicine, Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Hao Chiang
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yaw-Syan Fu
- Department of Biomedical Science and Environmental Biology, College of Science, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - June-Horng Lue
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Sung-Tsang Hsieh
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan
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Lebovitz EE, Keller JM, Kominsky H, Kaszas K, Maric D, Iadarola MJ. Positive allosteric modulation of TRPV1 as a novel analgesic mechanism. Mol Pain 2012; 8:70. [PMID: 22998799 PMCID: PMC3556054 DOI: 10.1186/1744-8069-8-70] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/11/2012] [Indexed: 12/21/2022] Open
Abstract
Background The prevalence of long-term opiate use in treating chronic non-cancer pain is increasing, and prescription opioid abuse and dependence are a major public health concern. To explore alternatives to opioid-based analgesia, the present study investigates a novel allosteric pharmacological approach operating through the cation channel TRPV1. This channel is highly expressed in subpopulations of primary afferent unmyelinated C- and lightly-myelinated Aδ-fibers that detect low and high rates of noxious heating, respectively, and it is also activated by vanilloid agonists and low pH. Sufficient doses of exogenous vanilloid agonists, such as capsaicin or resiniferatoxin, can inactivate/deactivate primary afferent endings due to calcium overload, and we hypothesized that positive allosteric modulation of agonist-activated TRPV1 could produce a selective, temporary inactivation of nociceptive nerve terminals in vivo. We previously identified MRS1477, a 1,4-dihydropyridine that potentiates vanilloid and pH activation of TRPV1 in vitro, but displays no detectable intrinsic agonist activity of its own. To study the in vivo effects of MRS1477, we injected the hind paws of rats with a non-deactivating dose of capsaicin, MRS1477, or the combination. An infrared diode laser was used to stimulate TRPV1-expressing nerve terminals and the latency and intensity of paw withdrawal responses were recorded. qRT-PCR and immunohistochemistry were performed on dorsal root ganglia to examine changes in gene expression and the cellular specificity of such changes following treatment. Results Withdrawal responses of the capsaicin-only or MRS1477-only treated paws were not significantly different from the untreated, contralateral paws. However, rats treated with the combination of capsaicin and MRS1477 exhibited increased withdrawal latency and decreased response intensity consistent with agonist potentiation and inactivation or lesion of TRPV1-containing nerve terminals. The loss of nerve endings was manifested by an increase in levels of axotomy markers assessed by qRT-PCR and colocalization of ATF3 in TRPV1+ cells visualized via immunohistochemistry. Conclusions The present observations suggest a novel, non-narcotic, selective, long-lasting TRPV1-based approach for analgesia that may be effective in acute, persistent, or chronic pain disorders.
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Affiliation(s)
- Evan E Lebovitz
- Neurobiology and Pain Therapeutics Section, Laboratory Of Sensory Biology, NIDCR, NIH, Bldg 49 Rm 1C2049 Convent Dr, Bethesda, MD 20892, USA
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Szallasi A, Sheta M. Targeting TRPV1 for pain relief: limits, losers and laurels. Expert Opin Investig Drugs 2012; 21:1351-69. [DOI: 10.1517/13543784.2012.704021] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Arpad Szallasi
- Monmouth Medical Center, Pathology, 300 Second Ave, Long Branch, 07740, USA
| | - Mohamed Sheta
- Monmouth Medical Center, Medicine, Long Branch, 07740, USA
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Iadarola MJ, Mannes AJ. The vanilloid agonist resiniferatoxin for interventional-based pain control. Curr Top Med Chem 2012; 11:2171-9. [PMID: 21671877 DOI: 10.2174/156802611796904942] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 11/26/2010] [Indexed: 11/22/2022]
Abstract
The idea of selectively targeting nociceptive transmission at the level of the peripheral nervous system is attractive from multiple perspectives, particularly the potential lack of non-specific (non-targeted) CNS side effects. Out of the multiple TRP channels involved in nociception, TRPV1 is a strong candidate based on its biophysical conductance properties and its expression in inflammation-sensitive dorsal root ganglion neurons and their axons and central and peripheral nerve terminals. While TRPV1 antagonists have undergone extensive medicinal chemical and pharmacological investigation, for TRPV1 agonists nature has provided an optimized compound in RTX. RTX is not suitable for systemic administration, but it is highly adaptable to a variety of pain problems when used by local administration. This can include routes as diverse as subcutaneous, intraganglionic or intrathecal (CSF space around the spinal cord). The present review focuses on the molecular and preclinical animal experiments that form the underpinnings of our clinical trial of intrathecal RTX for pain in advanced cancer. As such this represents a new approach to pain control that emerges from a long line of research on capsaicin and other vanilloids, their physiological actions, and the molecular biology of the capsaicin receptor TRPV1.
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Affiliation(s)
- Michael J Iadarola
- Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20892, USA.
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Hsieh YL, Chiang H, Lue JH, Hsieh ST. P2X3-mediated peripheral sensitization of neuropathic pain in resiniferatoxin-induced neuropathy. Exp Neurol 2012; 235:316-25. [PMID: 22391132 DOI: 10.1016/j.expneurol.2012.02.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 02/10/2012] [Accepted: 02/20/2012] [Indexed: 11/29/2022]
Abstract
Patients suffering from sensory neuropathy due to skin denervation frequently have paradoxical manifestations of reduced nociception and neuropathic pain. However, there is a lack of satisfactory animal models to investigate these phenomena and underlying mechanisms. We developed a mouse system of neuropathy induced by resiniferatoxin (RTX), a capsaicin analog, and examined the functional significance of P2X3 receptor in neuropathic pain. From day 7 of RTX neuropathy, mice displayed mechanical allodynia (p<0.0001) and thermal hypoalgesia (p<0.0001). After RTX treatment, dorsal root ganglion (DRG) neurons of the peripherin type were depleted (p=0.012), while neurofilament (+) DRG neurons were not affected (p=0.62). In addition, RTX caused a shift in neuronal profiles of DRG: (1) increased in P2X3 receptor (p=0.0002) and ATF3 (p=0.0006) but (2) reduced TRPV1 (p=0.036) and CGRP (p=0.015). The number of P2X3(+)/ATF3(+) neurons was linearly correlated with mechanical thresholds (p=0.0017). The peripheral expression of P2X3 receptor in dermal nerves was accordingly increased (p=0.016), and an intraplantar injection of the P2X3 antagonists, A-317491 and TNP-ATP, relieved mechanical allodynia in a dose-dependent manner. In conclusion, RTX-induced sensory neuropathy with upregulation of P2X3 receptor for peripheral sensitization of mechanical allodynia, which provides a new therapeutic target for neuropathic pain after skin denervation.
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Affiliation(s)
- Yu-Lin Hsieh
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei 10051, Taiwan
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Antinociceptive desensitizing actions of TRPV1 receptor agonists capsaicin, resiniferatoxin and N
-oleoyldopamine as measured by determination of the noxious heat and cold thresholds in the rat. Eur J Pain 2012; 14:480-6. [DOI: 10.1016/j.ejpain.2009.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 01/08/2023]
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Kaszas K, Keller JM, Coddou C, Mishra SK, Hoon MA, Stojilkovic S, Jacobson KA, Iadarola MJ. Small molecule positive allosteric modulation of TRPV1 activation by vanilloids and acidic pH. J Pharmacol Exp Ther 2011; 340:152-60. [PMID: 22005042 DOI: 10.1124/jpet.111.183053] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Transient receptor potential cation channel subfamily V member 1 (TRPV1) is a high-conductance, nonselective cation channel strongly expressed in nociceptive primary afferent neurons of the peripheral nervous system and functions as a multimodal nociceptor gated by temperatures greater than 43°C, protons, and small-molecule vanilloid ligands such as capsaicin. The ability to respond to heat, low pH, vanilloids, and endovanilloids and altered sensitivity and expression in experimental inflammatory and neuropathic pain models made TRPV1 a major target for the development of novel, nonopioid analgesics and resulted in the discovery of potent antagonists. In human clinical trials, observations of hyperthermia and the potential for thermal damage by suppressing the ability to sense noxious heat suggested that full-scale blockade of TRPV1 function can be counterproductive and subtler pharmacological approaches are necessary. Here we show that the dihydropyridine derivative 4,5-diethyl-3-(2-methoxyethylthio)-2-methyl-6-phenyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS1477) behaves as a positive allosteric modulator of both proton and vanilloid activation of TRPV1. Under inflammatory-mimetic conditions of low pH (6.0) and protein kinase C phosphorylation, addition of MRS1477 further increased sensitivity of already sensitized TPRV1 toward capsaicin. MRS1477 does not affect inhibition by capsazepine or ruthenium red and remains effective in potentiating activation by pH in the presence of an orthosteric vanilloid antagonist. These results indicate a distinct site on TRPV1 for positive allosteric modulation that may bind endogenous compounds or novel pharmacological agents. Positive modulation of TRPV1 sensitivity suggests that it may be possible to produce a selective analgesia through calcium overload restricted to highly active nociceptive nerve endings at sites of tissue damage and inflammation.
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Affiliation(s)
- Krisztian Kaszas
- Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
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TRP vanilloid 2 knock-out mice are susceptible to perinatal lethality but display normal thermal and mechanical nociception. J Neurosci 2011; 31:11425-36. [PMID: 21832173 DOI: 10.1523/jneurosci.1384-09.2011] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
TRP vanilloid 2 (TRPV2) is a nonselective cation channel expressed prominently in medium- to large-diameter sensory neurons that can be activated by extreme heat (>52°C). These features suggest that TRPV2 might be a transducer of noxious heat in vivo. TRPV2 can also be activated by hypoosmolarity or cell stretch, suggesting potential roles in mechanotransduction. To address the physiological functions of TRPV2 in somatosensation, we generated TRPV2 knock-out mice and examined their behavioral and electrophysiological responses to heat and mechanical stimuli. TRPV2 knock-out mice showed reduced embryonic weight and perinatal viability. As adults, surviving knock-out mice also exhibited a slightly reduced body weight. TRPV2 knock-out mice showed normal behavioral responses to noxious heat over a broad range of temperatures and normal responses to punctate mechanical stimuli, both in the basal state and under hyperalgesic conditions such as peripheral inflammation and L5 spinal nerve ligation. Moreover, behavioral assays of TRPV1/TRPV2 double knock-out mice or of TRPV2 knock-out mice treated with resiniferatoxin to desensitize TRPV1-expressing afferents revealed no thermosensory consequences of TRPV2 absence. In line with behavioral findings, electrophysiological recordings from skin afferents showed that C-fiber responses to heat and C- and Aδ-fiber responses to noxious mechanical stimuli were unimpaired in the absence of TRPV2. The prevalence of thermosensitive Aδ-fibers was too low to permit comparison between genotypes. Thus, TRPV2 is important for perinatal viability but is not essential for heat or mechanical nociception or hypersensitivity in the adult mouse.
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Bishnoi M, Bosgraaf CA, Abooj M, Zhong L, Premkumar LS. Streptozotocin-induced early thermal hyperalgesia is independent of glycemic state of rats: role of transient receptor potential vanilloid 1(TRPV1) and inflammatory mediators. Mol Pain 2011; 7:52. [PMID: 21794120 PMCID: PMC3157448 DOI: 10.1186/1744-8069-7-52] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 07/27/2011] [Indexed: 12/23/2022] Open
Abstract
Background Streptozotocin (STZ) is used as a common tool to induce diabetes and to study diabetes-induced complications including diabetic peripheral neuropathy (DPN). Previously, we have reported that STZ induces a direct effect on neurons through expression and function of the Transient receptor potential vanilloid 1 (TRPV1) channel in sensory neurons resulting in thermal hyperalgesia, even in non-diabetic STZ-treated mice. In the present study, we investigated the role of expression and function of TRPV1 in the central sensory nerve terminals in the spinal cord in STZ-induced hyperalgesia in rats. Results We found that a proportion of STZ-treated rats were normoglycemic but still exhibited thermal hyperalgesia and mechanical allodynia. Immunohistochemical data show that STZ treatment, irrespective of glycemic state of the animal, caused microglial activation and increased expression of TRPV1 in spinal dorsal horn. Further, there was a significant increase in the levels of pro-inflammatory mediators (IL-1β, IL-6 and TNF-α) in spinal cord tissue, irrespective of the glycemic state. Capsaicin-stimulated release of calcitonin gene related peptide (CGRP) was significantly higher in the spinal cord of STZ-treated animals. Intrathecal administration of resiniferatoxin (RTX), a potent TRPV1 agonist, significantly attenuated STZ-induced thermal hyperalgesia, but not mechanical allodynia. RTX treatment also prevented the increase in TRPV1-mediated neuropeptide release in the spinal cord tissue. Conclusions From these results, it is concluded that TRPV1 is an integral component of initiating and maintaining inflammatory thermal hyperalgesia, which can be alleviated by intrathecal administration of RTX. Further, the results suggest that enhanced expression and inflammation-induced sensitization of TRPV1 at the spinal cord may play a role in central sensitization in STZ-induced neuropathy.
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Affiliation(s)
- Mahendra Bishnoi
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, 62702, USA
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Rowbotham MC, Nothaft W, Duan RW, Wang Y, Faltynek C, McGaraughty S, Chu KL, Svensson P. Oral and cutaneous thermosensory profile of selective TRPV1 inhibition by ABT-102 in a randomized healthy volunteer trial. Pain 2011; 152:1192-1200. [PMID: 21377273 DOI: 10.1016/j.pain.2011.01.051] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 10/18/2022]
Abstract
The capsaicin receptor (TRPV1) antagonist ABT-102 demonstrates efficacy in multiple preclinical pain models. However, evolving clinical data for this compound class suggest potentially profound drug-induced thermosensory impairment. Safety and tolerability of ABT-102 were assessed in a multiple-dose, double-blind, placebo-controlled, randomized healthy volunteer trial. Thirty-six participants were randomized in a 2:1 ratio to ABT-102:placebo in 3 dose groups (1 mg, 2 mg, and 4 mg twice a day) and confined to an inpatient research unit for a 7-day treatment period and 3 follow-up days. Outcome measures included: oral and cutaneous cold detection, warm detection (WDT), and heat pain thresholds (HPT); oral perceived heat intensity (oral liquid test); time to hand withdrawal (water bath test); and cutaneous pain intensity (long thermal stimulus). Significant dose-dependent (placebo- and baseline-adjusted) increases in HPT and reduced painfulness of suprathreshold heat were present from days 1-7. For ABT-102 4 mg twice a day, model-based mean differences from placebo (95% confidence interval) were as follows: oral HPT, day 1=2.5°C (0.6-4.4), day 5=4.4°C (2.5-6.3); cutaneous HPT, day 2=3.3°C (1.4-5.3), day 5=5.3°C (3.3-7.2); oral WDT, day 1=2.6°C (0.5-4.7), day 5=2.7°C (0.6-4.9); cutaneous WDT, day 2=1.3 (0.0-2.6), day 5=1.6 (0.3-2.8) (all P<0.05). Oral liquid test and water bath test results followed a similar pattern. There was no effect on cutaneous cold detection. All effects were fully reversed by day 10. There were no other relevant safety findings. Core body temperature remained below 39°C in all participants. In conclusion, ABT-102 potently and reversibly increased HPT and reduced painfulness of suprathreshold oral/cutaneous heat.
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Affiliation(s)
- Michael C Rowbotham
- California Pacific Medical Center Research Institute, San Francisco, CA, USA Abbott Pain Care, Abbott Park, IL, USA Abbott Neuroscience and Pain Discovery, Abbott Park, IL, USA MINDLab, Center of Functionally Integrative Neuroscience, Aarhus University Hospital & Department of Clinical Oral Physiology, School of Dentistry, Aarhus University, Aarhus C, Denmark
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Laminitic pain: parallels with pain states in humans and other species. Vet Clin North Am Equine Pract 2011; 26:643-71. [PMID: 21056304 DOI: 10.1016/j.cveq.2010.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Laminitis poses a threat to all horses, and is widely considered as being one of the most important diseases of horses and a global equine welfare problem. The effects of laminitis lead to debilitation, development of pronounced digital pain, and great suffering in the afflicted animal. The precise pathophysiological processes that result in laminitic pain are poorly defined, and hence the delivery of effective palliative care is clinically challenging. Knowledge and understanding of pain states in other animal species may further aid the elucidation of equine laminitic pain mechanisms, guide the search for treatable causes of this multifactorial problem, and thereby help achieve enhanced therapeutic and palliative care. However, parallels drawn from pain states in other animals must consider species differences in both anatomy and physiology, and the specific nature of the laminitic disease process.
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Kumar PG, Shoeb M. The Role of TRP Ion Channels in Testicular Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 704:881-908. [DOI: 10.1007/978-94-007-0265-3_46] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Mitchell K, Bates BD, Keller JM, Lopez M, Scholl L, Navarro J, Madian N, Haspel G, Nemenov MI, Iadarola MJ. Ablation of rat TRPV1-expressing Adelta/C-fibers with resiniferatoxin: analysis of withdrawal behaviors, recovery of function and molecular correlates. Mol Pain 2010; 6:94. [PMID: 21167052 PMCID: PMC3019206 DOI: 10.1186/1744-8069-6-94] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 12/17/2010] [Indexed: 11/10/2022] Open
Abstract
Background Ablation of TRPV1-expressing nociceptive fibers with the potent capsaicin analog resiniferatoxin (RTX) results in long lasting pain relief. RTX is particularly adaptable to focal application, and the induced chemical axonopathy leads to analgesia with a duration that is influenced by dose, route of administration, and the rate of fiber regeneration. TRPV1 is expressed in a subpopulation of unmyelinated C- and lightly myelinated Adelta fibers that detect changes in skin temperature at low and high rates of noxious heating, respectively. Here we investigate fiber-type specific behaviors, their time course of recovery and molecular correlates of axon damage and nociception using infrared laser stimuli following an RTX-induced peripheral axonopathy. Results RTX was injected into rat hind paws (mid-plantar) to produce thermal hypoalgesia. An infrared diode laser was used to stimulate Adelta fibers in the paw with a small-diameter (1.6 mm), high-energy, 100 msec pulse, or C-fibers with a wide-diameter (5 mm), long-duration, low-energy pulse. We monitored behavioral responses to indicate loss and regeneration of fibers. At the site of injection, responses to C-fiber stimuli were significantly attenuated for two weeks after 5 or 50 ng RTX. Responses to Adelta stimuli were significantly attenuated for two weeks at the highest intensity stimulus, and for 5 weeks to a less intense Adelta stimulus. Stimulation on the toe, a site distal to the injection, showed significant attenuation of Adelta responses for 7- 8 weeks after 5 ng, or 9-10 weeks after 50 ng RTX. In contrast, responses to C-fiber stimuli exhibited basically normal responses at 5 weeks after RTX. During the period of fiber loss and recovery, molecular markers for nerve regeneration (ATF3 and galanin) are upregulated in the dorsal root ganglia (DRG) when behavior is maximally attenuated, but markers of nociceptive activity (c-Fos in spinal cord and MCP-1 in DRG), although induced immediately after RTX treatment, returned to normal. Conclusion Behavioral recovery following peripheral RTX treatment is linked to regeneration of TRPV1-expressing Adelta and C-fibers and sustained expression of molecular markers. Infrared laser stimulation is a potentially valuable tool for evaluating the behavioral role of Adelta fibers in pain and pain control.
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Affiliation(s)
- Kendall Mitchell
- Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, USA
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Bates B, Mitchell K, Keller JM, Chan CC, Swaim WD, Yaskovich R, Mannes AJ, Iadarola MJ. Prolonged analgesic response of cornea to topical resiniferatoxin, a potent TRPV1 agonist. Pain 2010; 149:522-528. [PMID: 20403666 PMCID: PMC2913152 DOI: 10.1016/j.pain.2010.03.024] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 02/22/2010] [Accepted: 03/18/2010] [Indexed: 11/22/2022]
Abstract
Analgesics currently available for the treatment of pain following ophthalmic surgery or injury are limited by transient effectiveness and undesirable or adverse side effects. The cornea is primarily innervated by small-diameter C-fiber sensory neurons expressing TRPV1 (transient receptor potential channel, subfamily V, member 1), a sodium/calcium cation channel expressed abundantly by nociceptive neurons and consequently a target for pain control. Resiniferatoxin (RTX), a potent TRPV1 agonist, produces transient analgesia when injected peripherally by inactivating TRPV1-expressing nerve terminals through excessive calcium influx. The aim of the present study was to evaluate topical RTX as a corneal analgesic. In rat cornea, a single application of RTX dose dependently eliminated or reduced the capsaicin eye wipe response for 3-5 days, with normal nociceptive responses returning by 5-7 days. RTX alone produced a brief but intense noxious response, similar to capsaicin, necessitating pretreatment of the cornea with a local anesthetic. Topical lidocaine, applied prior to RTX, blocks acute nociceptive responses to RTX without impairing the subsequent analgesic effect. Importantly, RTX analgesia (a) did not impair epithelial wound healing, (b) left the blink reflex intact and (c) occurred without detectable histological damage to the cornea. Immunohistochemistry showed that loss of CGRP immunoreactivity, a surrogate marker for TRPV1-expressing fibers, extended at least to the corneal-scleral boundary and displayed a progressive return, coincident with the return of capsaicin sensitivity. These data suggest that RTX may be a safe and effective treatment for post-operative or post-injury ophthalmic pain.
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Affiliation(s)
- Brian Bates
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
| | - Kendall Mitchell
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
| | - Jason M. Keller
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
| | - Chi-Chao Chan
- Immunopathology Section, National Eye Institute, National Institutes of Health, Bethesda MD 20982
| | - William D. Swaim
- Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
| | - Ruth Yaskovich
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
| | - Andrew J. Mannes
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
- Division of Anesthesia and Surgical Services, Clinical Center, National Institutes of Health, Bethesda MD 20982
| | - Michael J. Iadarola
- Neurobiology and Pain Therapeutics Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda MD 20982
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Schumacher MA. Transient receptor potential channels in pain and inflammation: therapeutic opportunities. Pain Pract 2010; 10:185-200. [PMID: 20230457 DOI: 10.1111/j.1533-2500.2010.00358.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In ancient times, physicians had a limited number of therapies to provide pain relief. Not surprisingly, plant extracts applied topically often served as the primary analgesic plan. With the discovery of the capsaicin receptor (transient receptor potential cation channel, subfamily V, member 1 [TRPV1]), the search for "new" analgesics has returned to compounds used by physicians thousands of years ago. One such compound, capsaicin, couples the paradoxical action of nociceptor activation (burning pain) with subsequent analgesia following repeat or high-dose application. Investigating this "paradoxical" action of capsaicin has revealed several overlapping and complementary mechanisms to achieve analgesia including receptor desensitization, nociceptor dysfunction, neuropeptide depletion, and nerve terminal destruction. Moreover, the realization that TRPV1 is both sensitized and activated by endogenous products of inflammation, including bradykinin, H+, adenosine triphosphate, fatty acid derivatives, nerve growth factor, and trypsins, has renewed interest in TRPV1 as an important site of analgesia. Building on this foundation, a new series of preclinical and clinical studies targeting TRPV1 has been reported. These include trials using brief exposure to high-dose topical capsaicin in conjunction with prior application of a local anesthetic. Clinical use of resiniferatoxin, another ancient but potent TRPV1 agonist, is also being explored as a therapy for refractory pain. The development of orally administered high-affinity TRPV1 antagonists holds promise for pioneering a new generation of analgesics capable of blocking painful sensations at the site of inflammation and tissue injury. With the isolation of other members of the TRP channel family such as TRP cation channel, subfamily A, member 1, additional opportunities are emerging in the development of safe and effective analgesics.
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Affiliation(s)
- Mark A Schumacher
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, California 94143-0427, USA.
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