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Szallasi A. Targeting TRPV1 for Cancer Pain Relief: Can It Work? Cancers (Basel) 2024; 16:648. [PMID: 38339399 PMCID: PMC11154559 DOI: 10.3390/cancers16030648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/23/2024] [Accepted: 01/31/2024] [Indexed: 02/12/2024] Open
Abstract
Chronic intractable pain affects a large proportion of cancer patients, especially those with metastatic bone disease. Blocking sensory afferents for cancer pain relief represents an attractive alternative to opioids and other drugs acting in the CNS in that sensory nerve blockers are not addictive and do not affect the mental state of the patient. A distinct subpopulation of sensory afferents expresses the capsaicin receptor TRPV1. Intrathecal resiniferatoxin, an ultrapotent capsaicin analog, ablates TRPV1-expressing nerve endings exposed to the cerebrospinal fluid, resulting in permanent analgesia in women with cervical cancer metastasis to the pelvic bone. High-dose capsaicin patches are effective pain killers in patients with chemotherapy-induced peripheral neuropathic pain. However, large gaps remain in our knowledge since the mechanisms by which cancer activates TRPV1 are essentially unknown. Most important, it is not clear whether or not sensory denervation mediated by TRPV1 agonists affects cancer progression. In a murine model of breast cancer, capsaicin desensitization was reported to accelerate progression. By contrast, desensitization mediated by resiniferatoxin was found to block melanoma growth. These observations imply that TRPV1 blockade for pain relief may be indicated for some cancers and contraindicated for others. In this review, we explore the current state of this field and compare the analgesic potential of TRPV1 antagonism and sensory afferent desensitization in cancer patients.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology and Experimental Cancer Research, Semmelweis University, 1085 Budapest, Hungary
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2
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Szallasi A. Resiniferatoxin: Nature's Precision Medicine to Silence TRPV1-Positive Afferents. Int J Mol Sci 2023; 24:15042. [PMID: 37894723 PMCID: PMC10606200 DOI: 10.3390/ijms242015042] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/27/2023] [Accepted: 10/07/2023] [Indexed: 10/29/2023] Open
Abstract
Resiniferatoxin (RTX) is an ultrapotent capsaicin analog with a unique spectrum of pharmacological actions. The therapeutic window of RTX is broad, allowing for the full desensitization of pain perception and neurogenic inflammation without causing unacceptable side effects. Intravesical RTX was shown to restore continence in a subset of patients with idiopathic and neurogenic detrusor overactivity. RTX can also ablate sensory neurons as a "molecular scalpel" to achieve permanent analgesia. This targeted (intrathecal or epidural) RTX therapy holds great promise in cancer pain management. Intra-articular RTX is undergoing clinical trials to treat moderate-to-severe knee pain in patients with osteoarthritis. Similar targeted approaches may be useful in the management of post-operative pain or pain associated with severe burn injuries. The current state of this field is reviewed, from preclinical studies through veterinary medicine to clinical trials.
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Affiliation(s)
- Arpad Szallasi
- Department of Pathology and Experimental Cancer Research, Semmelweis University, 1083 Budapest, Hungary
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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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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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5
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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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Isensee J, Hucho T. High-Content Imaging of Immunofluorescently Labeled TRPV1-Positive Sensory Neurons. Methods Mol Biol 2019; 1987:111-124. [PMID: 31028677 DOI: 10.1007/978-1-4939-9446-5_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Studying TRP channel expressing nociceptors requires the identification of the respective subpopulations as well as the quantification of dynamic cellular events. However, the heterogeneity of sensory neurons and associated nonneuronal cells demands the analysis of large numbers of cells to reflect the distribution of entire populations. Here we report a detailed workflow how to apply high-content screening (HCS) microscopy to signaling events in TRPV1-positive neurons as well as an approach to use the selective elimination of TRPV1 positive cells from dissociated rat sensory ganglia as base for transcriptomic analysis of TRPV1-positive cells and/or as control for TRPV1 antibody specificity.
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Affiliation(s)
- Jörg Isensee
- Experimental Anesthesiology and Pain Research, Department of Anesthesiology and Intensive Care Medicine, University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Tim Hucho
- Experimental Anesthesiology and Pain Research, Department of Anesthesiology and Intensive Care Medicine, University Hospital Cologne, University of Cologne, Cologne, Germany.
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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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O'Leary VB, O'Connell M, Antyborzec I, Ntziachristos V, Oliver Dolly J, Ovsepian SV. Alleviation of Trigeminal Nociception Using p75 Neurotrophin Receptor Targeted Lentiviral Interference Therapy. Neurotherapeutics 2018; 15:489-499. [PMID: 29427180 PMCID: PMC5935639 DOI: 10.1007/s13311-018-0608-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Acute and chronic trigeminal (TG) neuropathies are the cause of considerable distress, with limited treatments available at present. Nociceptive neurons enriched with the vanilloid type 1 receptor (VR1) partake in pain sensation and sensitization in the TG system. While VR1 blockers with anti-nociceptive potential are of substantial medical interest, their use remains limited due to poor selectivity and lack of cell-targeting capabilities. This study describes a methodology for the alleviation of nociception via targeted depletion of VR1 in TG sensory neurons in rats. In cultured TG ganglion neurons, VR1 expression was virtually abolished by lentiviral short hairpin RNA (LV-VR1). By decorating GFP encoding LV (LV-GFP) and LV-VR1 with IgG192 for targeting TG sensory neurons enriched with the p75 neurotrophin receptor (p75NTR), transduction of a reporter GFP and VR1 depletion was achieved after injection of targeted vectors into the whisker pad. In IgG192/LV-VR1-injected rats, the behavioral response to capsaicin exposure as well as Erk 1/2 phosphorylation and VR1 current activation by capsaicin were significantly reduced. This pioneering investigation, thus, provides a proof of principle for a means of attenuating TG nociception, revealing therapeutic potential.
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Affiliation(s)
- Valerie B O'Leary
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Marie O'Connell
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Inga Antyborzec
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Vasilis Ntziachristos
- Helmholtz Zentrum München - German Research Center for Environmental Health, Institute for Biological and Medical Imaging, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
- Faculty for Electrical Engineering and Information Technology, Chair of Biomedical Imaging, Technical University of Munich, Munich, Germany
| | - J Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Saak V Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland.
- Helmholtz Zentrum München - German Research Center for Environmental Health, Institute for Biological and Medical Imaging, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany.
- Faculty for Electrical Engineering and Information Technology, Chair of Biomedical Imaging, Technical University of Munich, Munich, Germany.
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Sapio MR, Neubert JK, LaPaglia DM, Maric D, Keller JM, Raithel SJ, Rohrs EL, Anderson EM, Butman JA, Caudle RM, Brown DC, Heiss JD, Mannes AJ, Iadarola MJ. Pain control through selective chemo-axotomy of centrally projecting TRPV1+ sensory neurons. J Clin Invest 2018; 128:1657-1670. [PMID: 29408808 DOI: 10.1172/jci94331] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 02/01/2018] [Indexed: 11/17/2022] Open
Abstract
Agonists of the vanilloid receptor transient vanilloid potential 1 (TRPV1) are emerging as highly efficacious nonopioid analgesics in preclinical studies. These drugs selectively lesion TRPV1+ primary sensory afferents, which are responsible for the transmission of many noxious stimulus modalities. Resiniferatoxin (RTX) is a very potent and selective TRPV1 agonist and is a promising candidate for treating many types of pain. Recent work establishing intrathecal application of RTX for the treatment of pain resulting from advanced cancer has demonstrated profound analgesia in client-owned dogs with osteosarcoma. The present study uses transcriptomics and histochemistry to examine the molecular mechanism of RTX action in rats, in clinical canine subjects, and in 1 human subject with advanced cancer treated for pain using intrathecal RTX. In all 3 species, we observe a strong analgesic action, yet this was accompanied by limited transcriptional alterations at the level of the dorsal root ganglion. Functional and neuroanatomical studies demonstrated that intrathecal RTX largely spares susceptible neuronal perikarya, which remain active peripherally but unable to transmit signals to the spinal cord. The results demonstrate that central chemo-axotomy of the TRPV1+ afferents underlies RTX analgesia and refine the neurobiology underlying effective clinical use of TRPV1 agonists for pain control.
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Affiliation(s)
- Matthew R Sapio
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
| | - John K Neubert
- Department of Orthodontics, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Danielle M LaPaglia
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
| | - Dragan Maric
- Flow Cytometry Core Facility, NIH, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA
| | - Jason M Keller
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
| | - Stephen J Raithel
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
| | - Eric L Rohrs
- Department of Orthodontics, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Ethan M Anderson
- Department of Oral and Maxillofacial Surgery, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - John A Butman
- Clinical Center, Radiology and Imaging Services, NIH, Bethesda, Maryland, USA
| | - Robert M Caudle
- Department of Oral and Maxillofacial Surgery, University of Florida College of Dentistry, Gainesville, Florida, USA
| | - Dorothy C Brown
- Veterinary Clinical Investigations Center, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
| | - John D Heiss
- Surgical Neurology Branch, NIH, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, USA
| | - Andrew J Mannes
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
| | - Michael J Iadarola
- Clinical Center, Department of Perioperative Medicine, NIH, Bethesda, Maryland, USA
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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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Austah ON, Ruparel NB, Henry MA, Fajardo RJ, Schmitz JE, Diogenes A. Capsaicin-sensitive Innervation Modulates the Development of Apical Periodontitis. J Endod 2016; 42:1496-502. [PMID: 27523907 DOI: 10.1016/j.joen.2016.06.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 06/07/2016] [Accepted: 06/16/2016] [Indexed: 01/04/2023]
Abstract
INTRODUCTION Nociceptive neurons play a critical role in the detection of stimuli evoking actual or potential tissue injury. In addition, they are involved in neurogenic inflammation by the peripheral release of neuropeptides such as calcitonin gene-related peptide (CGRP). The dental pulp and periradicular tissues are innervated by capsaicin-sensitive neurons known to release CGRP. However, the role of these capsaicin-sensitive neurons in the development of apical periodontitis is largely unknown. The aim of this study was to evaluate the contribution of peptidergic neurons to the development of apical periodontitis. METHODS Neonatal Sprague-Dawley rats were injected with vehicle (control group) or a single subcutaneous capsaicin dose to cause the selective ablation of peptidergic neurons (neonatal capsaicin group). Ablation of capsaicin-sensitive neurons was verified with confocal microscopy, capsaicin-induced eye-wipe nocifensive behavior test, and by measurement of immunoreactive CGRP levels in the dental pulp. Five weeks after ablation, standardized pulp exposures were made in the mandibular left first molars. Mandibles were harvested at 7, 14, 21, and 28 days after pulp exposure and imaged with micro-computed tomography (μCT) to quantify apical lesion volume. Data were analyzed by using 2-way ANOVA analysis with Bonferroni post hoc test. RESULTS Rats in the control group displayed a robust capsaicin-induced nocifensive behavior, which was nearly abolished in the neonatal capsaicin group. In addition, the neonatal capsaicin group showed a significant depletion of susceptible neurons and CGRP in the dental pulp compared with control. Importantly, micro-computed tomography analysis showed larger periradicular lesions at 7 and 14 days after pulp exposure in the neonatal capsaicin group when compared with control. CONCLUSIONS Results identify a protective role for capsaicin-sensitive neurons in the initial phase of apical periodontitis. Thus, interventions or disorders that alter activity of capsaicin-sensitive fibers are likely to alter the development of apical periodontitis.
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Affiliation(s)
- Obadah N Austah
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas; Department of Endodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nikita B Ruparel
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Michael A Henry
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Roberto J Fajardo
- Department of Orthopedics, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - James E Schmitz
- Department of Orthopedics, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Anibal Diogenes
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
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12
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Brown DC. Resiniferatoxin: The Evolution of the "Molecular Scalpel" for Chronic Pain Relief. Pharmaceuticals (Basel) 2016; 9:ph9030047. [PMID: 27529257 PMCID: PMC5039500 DOI: 10.3390/ph9030047] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/04/2016] [Accepted: 08/09/2016] [Indexed: 11/16/2022] Open
Abstract
Control of chronic pain is frequently inadequate or can be associated with debilitating side effects. Ablation of certain nociceptive neurons, while retaining all other sensory modalities and motor function, represents a new therapeutic approach to controlling severe pain while avoiding off-target side effects. transient receptor potential cation channel subfamily V member 1 (TRPV1) is a calcium permeable nonselective cation channel expressed on the peripheral and central terminals of small-diameter sensory neurons. Highly selective chemoablation of TRPV1-containing peripheral nerve endings, or the entire TRPV1-expressing neuron itself, can be used to control chronic pain. Administration of the potent TRPV1 agonist resiniferatoxin (RTX) to neuronal perikarya or nerve terminals induces calcium cytotoxicity and selective lesioning of the TRPV1-expressing nociceptive primary afferent population. This selective neuroablation has been coined "molecular neurosurgery" and has the advantage of sparing motor, proprioceptive, and other somatosensory functions that are so important for coordinated movement, performing activities of daily living, and maintaining quality of life. This review examines the mechanisms and preclinical data underlying the therapeutic use of RTX and examples of such use for the management of chronic pain in clinical veterinary and human pain states.
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Affiliation(s)
- Dorothy Cimino Brown
- Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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13
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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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Isensee J, Wenzel C, Buschow R, Weissmann R, Kuss AW, Hucho T. Subgroup-elimination transcriptomics identifies signaling proteins that define subclasses of TRPV1-positive neurons and a novel paracrine circuit. PLoS One 2014; 9:e115731. [PMID: 25551770 PMCID: PMC4281118 DOI: 10.1371/journal.pone.0115731] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 11/29/2014] [Indexed: 12/24/2022] Open
Abstract
Normal and painful stimuli are detected by specialized subgroups of peripheral sensory neurons. The understanding of the functional differences of each neuronal subgroup would be strongly enhanced by knowledge of the respective subgroup transcriptome. The separation of the subgroup of interest, however, has proven challenging as they can hardly be enriched. Instead of enriching, we now rapidly eliminated the subgroup of neurons expressing the heat-gated cation channel TRPV1 from dissociated rat sensory ganglia. Elimination was accomplished by brief treatment with TRPV1 agonists followed by the removal of compromised TRPV1(+) neurons using density centrifugation. By differential microarray and sequencing (RNA-Seq) based expression profiling we compared the transcriptome of all cells within sensory ganglia versus the same cells lacking TRPV1 expressing neurons, which revealed 240 differentially expressed genes (adj. p<0.05, fold-change>1.5). Corroborating the specificity of the approach, many of these genes have been reported to be involved in noxious heat or pain sensitization. Beyond the expected enrichment of ion channels, we found the TRPV1 transcriptome to be enriched for GPCRs and other signaling proteins involved in adenosine, calcium, and phosphatidylinositol signaling. Quantitative population analysis using a recent High Content Screening (HCS) microscopy approach identified substantial heterogeneity of expressed target proteins even within TRPV1-positive neurons. Signaling components defined distinct further subgroups within the population of TRPV1-positive neurons. Analysis of one such signaling system showed that the pain sensitizing prostaglandin PGD2 activates DP1 receptors expressed predominantly on TRPV1(+) neurons. In contrast, we found the PGD2 producing prostaglandin D synthase to be expressed exclusively in myelinated large-diameter neurons lacking TRPV1, which suggests a novel paracrine neuron-neuron communication. Thus, subgroup analysis based on the elimination rather than enrichment of the subgroup of interest revealed proteins that define subclasses of TRPV1-positive neurons and suggests a novel paracrine circuit.
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Affiliation(s)
- Jörg Isensee
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Cologne, Germany
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
- * E-mail:
| | - Carsten Wenzel
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Rene Buschow
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Robert Weissmann
- Department of Human Genetics, University Medicine Greifswald and Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Andreas W. Kuss
- Department of Human Genetics, University Medicine Greifswald and Interfaculty Institute of Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Tim Hucho
- Department of Anesthesiology and Intensive Care Medicine, Experimental Anesthesiology and Pain Research, University Hospital of Cologne, Cologne, Germany
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
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16
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Abstract
Objectives:Resiniferatoxin, the most potent agonist of inflammatory pain/vanilloid receptor/cation channel (TRPV1) can be used for neuron subtype specific ablation of pain generating cells at the level of the peripheral nervous system by Ca2+-excytotoxicity. Molecular neurosurgery is an emerging technology either to alleviate severe pain in cancer or treat/prevent different local neuropathies. Our aim was determining sensory modalities that may be lost after resiniferatoxin treatment.Methods:Newborn or adult mice were treated with resiniferatoxin, then changes in chemical and heat sensitivity were correlated with alterations of the cell composition of sensory ganglions.Results:Only mice treated at adult age became less sensitive to heat stimuli, while both treatment groups lost sensitivity to specific vanilloid agonists of TRPV1 and, interestingly, to allyl-isothiocyanate, a selective agonist of TRPA1. Our in vivo and post mortem analytical results confirmed that TRPV1 and TRPA1 function together and resiniferatoxin-mediated neurosurgery removes both sensor moleculesDiscussion:In adult mice resiniferatoxin causes: i) desensitization to heat and ii) sensitization to cold. Cold hyperalgesia, an imbalance in thermosensation, might be conferred by a prominent cold receptor that is expressed in surviving resiniferatoxin-resistant sensory neurons and compensates for pain signals lost with TRPA1 and TRPV1 double positive cells in the peripheral nervous system.
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Tender GC, Li YY, Cui JG. The role of nerve growth factor in neuropathic pain inhibition produced by resiniferatoxin treatment in the dorsal root ganglia. Neurosurgery 2014; 73:158-65; discussion 165-6. [PMID: 23615109 DOI: 10.1227/01.neu.0000429850.37449.c8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Resiniferatoxin (RTX), an excitotoxic agonist for vanilloid receptor 1, is a promising candidate for intractable pain treatment. OBJECTIVE We evaluated the effects of RTX, applied to dorsal root ganglia (DRG) at high doses (1200 ng), in sensory-motor function and nerve growth factor (NGF) alterations in a photochemical sciatic nerve injury rat model. METHODS Following RTX injection into the L3-6 DRG at high doses and behavioral evaluation, the rats were sacrificed and the DRG were tested by immunohistochemistry and mRNA analysis for NGF and its' receptors, tyrosine kinase A (TrkA) and p75. The correlation between neuropathic pain and NGF, TrkA, and p75 expression was analyzed. RESULTS The treated rats had preserved touch, cold, pain, and high-heat sensations, and exhibited hypoalgesia to low-heat stimulation. After RTX treatment, TrkA and p75 altered their expressions from one neuronal type to another in the DRG. NGF and p75 expression changed from the small-size neurons in neuropathic rat DRG to the large- and medium-size neurons in non-neuropathic and RTX-treated animals, concomitantly with neuropathic pain suppression. TrkA was expressed in the small-size neurons in neuropathic rat DRG, and was drastically reduced in all size neurons after RTX treatment. NGF, TrkA, and p75 mRNA expression supported these phenotypic changes in the DRG. CONCLUSION The pathway of NGF-TrkA expressed in the small-size neurons, associated with neuropathic pain, was shifted to the NGF-p75 pathway expressed in the large-size neurons after RTX treatment, in association with neuropathic pain inhibition. These findings may play an important role in clinical trial designs.
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Affiliation(s)
- Gabriel C Tender
- Department of Neurosurgery, Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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Kim MJ, Lee SY, Yang KY, Nam SH, Kim HJ, Kim YJ, Bae YC, Ahn DK. Differential regulation of peripheral IL-1β-induced mechanical allodynia and thermal hyperalgesia in rats. Pain 2014; 155:723-732. [PMID: 24406203 DOI: 10.1016/j.pain.2013.12.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/18/2013] [Accepted: 12/30/2013] [Indexed: 11/29/2022]
Abstract
This study examined the differential mechanisms of mechanical allodynia and thermal hyperalgesia after injection of interleukin (IL) 1β into the orofacial area of male Sprague-Dawley rats. The subcutaneous administration of IL-1β produced both mechanical allodynia and thermal hyperalgesia. Although a pretreatment with iodoresiniferatoxin (IRTX), a transient receptor potential vanilloid 1 (TRPV1) antagonist, did not affect IL-1β-induced mechanical allodynia, it significantly abolished IL-1β-induced thermal hyperalgesia. On the other hand, a pretreatment with D-AP5, an N-methyl-d-aspartate (NMDA) receptor antagonist, and NBQX, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, blocked IL-1β-induced mechanical allodynia. Pretreatment with H89, a protein kinase A (PKA) inhibitor, blocked IL-1β-induced mechanical allodynia but not thermal hyperalgesia. In contrast, pretreatment with chelerythrine, a protein kinase C (PKC) inhibitor, inhibited IL-1β-induced thermal hyperalgesia. Subcutaneous injections of 2% lidocaine, a local anesthetic agent, blocked IL-1β-induced thermal hyperalgesia but not IL-1β-induced mechanical allodynia. In the resiniferatoxin (RTX)-pretreated rats, a subcutaneous injection of IL-1β did not produce thermal hyperalgesia due to the depletion of TRPV1 in the primary afferent fibers. Double immunofluorescence revealed the colocalization of PKA with neurofilament 200 (NF200) and of PKC with the calcitonin gene-related peptide (CGRP) in the trigeminal ganglion. Furthermore, NMDA receptor 1 (NR1) and TRPV1 predominantly colocalize with PKA and PKC, respectively, in the trigeminal ganglion. These results suggest that IL-1β-induced mechanical allodynia is mediated by sensitized peripheral NMDA/AMPA receptors through PKA-mediated signaling in the large-diameter primary afferent nerve fibers, whereas IL-1β-induced thermal hyperalgesia is mediated by sensitized peripheral TRPV1 receptors through PKC-mediated signaling in the small-diameter primary afferent nerve fibers.
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Affiliation(s)
- Min J Kim
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea Department of Pediatric Dentistry, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea Department of Oral Anatomy, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea
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Nagy I, Friston D, Valente JS, Torres Perez JV, Andreou AP. Pharmacology of the capsaicin receptor, transient receptor potential vanilloid type-1 ion channel. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2014; 68:39-76. [PMID: 24941664 DOI: 10.1007/978-3-0348-0828-6_2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The capsaicin receptor, transient receptor potential vanilloid type 1 ion channel (TRPV1), has been identified as a polymodal transducer molecule on a sub-set of primary sensory neurons which responds to various stimuli including noxious heat (> -42 degrees C), protons and vanilloids such as capsaicin, the hot ingredient of chilli peppers. Subsequently, TRPV1 has been found indispensable for the development of burning pain and reflex hyperactivity associated with inflammation of peripheral tissues and viscera, respectively. Therefore, TRPV1 is regarded as a major target for the development of novel agents for the control of pain and visceral hyperreflexia in inflammatory conditions. Initial efforts to introduce agents acting on TRPV1 into clinics have been hampered by unexpected side-effects due to wider than expected expression in various tissues, as well as by the complex pharmacology, of TRPV1. However, it is believed that better understanding of the pharmacological properties of TRPV1 and specific targeting of tissues may eventually lead to the development of clinically useful agents. In order to assist better understanding of TRPV1 pharmacology, here we are giving a comprehensive account on the activation and inactivation mechanisms and the structure-function relationship of TRPV1.
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20
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Min JW, Liu WH, He XH, Peng BW. Different types of toxins targeting TRPV1 in pain. Toxicon 2013; 71:66-75. [PMID: 23732125 DOI: 10.1016/j.toxicon.2013.05.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 05/14/2013] [Accepted: 05/22/2013] [Indexed: 02/06/2023]
Abstract
The transient receptor potential vanilloid 1(TRPV1) channels are members of the transient receptor potential (TRP) superfamily. Members of this family are expressed in primary sensory neurons and are best known for their role in nociception and sensory transmission. Multiple painful stimuli can activate these channels. In this review, we discussed the mechanisms of different types of venoms that target TRPV1, such as scorpion venom, botulinum neurotoxin, spider toxin, ciguatera fish poisoning (CFP) and neurotoxic shellfish poisoning (NSP). Some of these toxins activate TRPV1; however, some do not. Regardless of TRPV1 inhibition or activation, they occur through different pathways. For example, BoNT/A decreases TRPV1 expression levels by blocking TRPV1 trafficking to the plasma membrane, although the exact mechanism is still under debate. Vanillotoxins from tarantula (Psalmopoeus cambridgei) are proposed to activate TRPV1 via interaction with a region of TRPV1 that is homologous to voltage-dependent ion channels. Here, we offer a description of the present state of knowledge for this complex subject.
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Affiliation(s)
- Jia-Wei Min
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, 185 Donghu Road, Wuhan, Hubei 430071, PR China
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21
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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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22
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Pecze L, Winter Z, Jósvay K, Ötvös F, Kolozsi C, Vizler C, Budai D, Letoha T, Dombi G, Szakonyi G, Oláh Z. Divalent heavy metal cations block the TRPV1 Ca(2+) channel. Biol Trace Elem Res 2013; 151:451-61. [PMID: 23264033 PMCID: PMC3566393 DOI: 10.1007/s12011-012-9570-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 12/03/2012] [Indexed: 01/17/2023]
Abstract
Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel involved in pain sensation and in a wide range of non-pain-related physiological and pathological conditions. The aim of the present study was to explore the effects of selected heavy metal cations on the function of TRPV1. The cations ranked in the following sequence of pore-blocking activity: Co(2+) [half-maximal inhibitory concentration (IC(50)) = 13 μM] > Cd(2+) (I (50) = 38 μM) > Ni(2+) (IC(50) = 62 μM) > Cu(2+) (IC(50) = 200 μM). Zn(2+) proved to be a weak (IC(50) = 27 μM) and only partial inhibitor of the channel function, whereas Mg(2+), Mn(2+) and La(3+) did not exhibit any substantial effect. Co(2+), the most potent channel blocker, was able not only to compete with Ca(2+) but also to pass with it through the open channel of TRPV1. In response to heat activation or vanilloid treatment, Co(2+) accumulation was verified in TRPV1-transfected cell lines and in the TRPV1+ dorsal root ganglion neurons. The inhibitory effect was also demonstrated in vivo. Co(2+) applied together with vanilloid agonists attenuated the nocifensive eye wipe response in mice. Different rat TRPV1 pore point mutants (Y627W, N628W, D646N and E651W) were created that can validate the binding site of previously used channel blockers in agonist-evoked (45)Ca(2+) influx assays in cells expressing TRPV1. The IC(50) of Co(2+) on these point mutants were determined to be reasonably comparable to those on the wild type, which suggests that divalent cations passing through the TRPV1 channel use the same negatively charged amino acids as Ca(2+).
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Affiliation(s)
- László Pecze
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltán Winter
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
| | - Katalin Jósvay
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Ferenc Ötvös
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- Greenformatix Nonprofit Ltd., Szeged, Hungary
| | - Csongor Kolozsi
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Csaba Vizler
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | | | - Tamás Letoha
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
- Pharmacoidea Ltd., Szeged, Hungary
| | - György Dombi
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
| | - Gerda Szakonyi
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
| | - Zoltán Oláh
- Institute of Pharmaceutical Analysis, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
- Acheuron Hungary Ltd., Szeged, Hungary
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23
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Haanpää M, Treede RD. Capsaicin for neuropathic pain: linking traditional medicine and molecular biology. Eur Neurol 2012; 68:264-75. [PMID: 23037991 DOI: 10.1159/000339944] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 05/29/2012] [Indexed: 12/13/2022]
Abstract
Capsaicin has long been used as a traditional medicine to treat pain and, recently, its mechanism of analgesic action has been discovered. This review article documents the clinical development of capsaicin to demonstrate that pharmacognosy still has a profound influence on modern-day drug development programs. Capsaicin is a highly selective agonist for the transient receptor potential channel vanilloid-receptor type 1 (TRPV1), which is expressed on central and peripheral terminals of nociceptive primary sensory neurons. Knockout studies have revealed the importance of TRPV1 as a molecular pain integrator and target for novel analgesic agents. Topical application of capsaicin at the peripheral terminal of TRPV1-expressing neurons superficially denervates the epidermis in humans in a highly selective manner and results in hypoalgesia. In three recent randomized controlled trials, a patch containing high-concentration capsaicin demonstrated meaningful efficacy and tolerability relative to a low-concentration capsaicin control patch in patients with peripheral neuropathic pain. Data from clinical practice will determine if the high-concentration capsaicin patch is effective in real-world settings.
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Affiliation(s)
- Maija Haanpää
- Department of Neurosurgery, Helsinki University Central Hospital, Töölö Hospital, Helsinki, Finland
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24
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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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25
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Change in prostaglandin expression levels and synthesizing activities in dry eye disease. Ophthalmology 2012; 119:2211-9. [PMID: 22858125 DOI: 10.1016/j.ophtha.2012.05.038] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 05/23/2012] [Accepted: 05/23/2012] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE To investigate the expression level of prostaglandins (PGs) and their de novo synthesis in dry eye (DE) disease. DESIGN Cross-sectional case-control study and in vivo mouse experimental study. PARTICIPANTS Forty-six eyes from 23 DE patients and 33 eyes from 17 age- and sex-matched controls were studied. Also, DE-induced murine eyes were compared with control eyes. METHODS Patients completed a symptom questionnaire using a 100-mm visual analog scale (VAS). Nano-liquid chromatography tandem mass spectrometry was used for the quantification of PGE2 and PGD2. A DE disease environmental chamber was used to induce DE in mice. One week after induction, enzyme expressions of cyclooxygenase-1, cyclooxygenase-2 (COX-2), PG E synthase (PGES), and PG D synthase (PGDS) in the lacrimal glands, meibomian glands, and corneas were examined using immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). MAIN OUTCOME MEASURES The mean PGE2 and PGD2 levels in the tears of DE patients were measured and compared with symptom severity scores. Immunohistochemistry staining patterns and qRT-PCR data of DE mice were quantified. RESULTS The mean PGE2 level in the tears of DE patients (2.72 ±3 .42 ng/ml) was significantly higher than that in the control group (0.88 ± 0.83 ng/ml; P = 0.003). However, the mean PGD2 level in the tears of DE patients (0.11 ± 0.22 ng/ml) was significantly lower (0.91 ± 3.28 ng/ml; P = 0.028). The mean PGE2-to-PGD2 ratio correlated strongly with VAS scoring (P = 0.008). In DE mice, COX-2 mRNA was significantly higher in ocular surface tissue and lacrimal glands. Furthermore, PGES mRNA was significantly higher in ocular surface tissue, whereas PGDS mRNA was decreased. Immunohistochemistry staining showed elevated COX-2 expression in the lacrimal glands, meibomian glands, corneas, and conjunctivas. Furthermore, PGES expression was found in periductal infiltrated cells of the lacrimal glands and conjunctival epithelium. Also, PGDS expression was decreased in meibomian glands and increased focally in the conjunctival epithelium. CONCLUSIONS A reciprocal change in PGE2 and PGD2 levels was found in the tears of DE patients, which correlated with patients' symptom scores. These clinical results were supported by increased COX-2 and PGES expression levels found in tear-producing tissues of DE mice.
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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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Tender GC, Kaye AD, Li YY, Cui JG. Neurotrophin-3 and tyrosine kinase C have modulatory effects on neuropathic pain in the rat dorsal root ganglia. Neurosurgery 2012; 68:1048-55; discussion 1055. [PMID: 21221027 DOI: 10.1227/neu.0b013e318208f9c4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Neurotrophin-3 (NT3) and its cognate receptor, tyrosine kinase C (TrkC), have recently been shown to modulate neuropathic pain. Another receptor, the transient receptor potential vanilloid 1, is considered a molecular integrator for nociception. Transient receptor potential vanilloid 1-positive cells can be selectively ablated by Resiniferatoxin (RTX). NT3 changes in the dorsal root ganglia (DRG) after RTX treatment may further define their role in pain modulation. OBJECTIVE To demonstrate the role of NT3 and TrkC in intraganglial RTX-induced pain suppression and in neuropathic pain development. METHODS Fifty-three rats underwent a photochemical left sciatic nerve injury. Neuropathic animals were treated by RTX injection in the ipsilateral L3-6 DRG. NT3 and TrkC presence in the DRG was evaluated before and after the nerve injury, as well as after RTX treatment. RESULTS The RTX injection resulted in pain inhibition. NT3 normally expressed mainly in large- and medium-size neurons. NT3 presence was increased mainly in the small DRG cells of neuropathic animals, and the medium- and large-size neurons of nonallodynic rats. RTX treatment of allodynic rats changed the NT3 distribution to a nonallodynic pattern. TrkC expressed mainly in large/medium-size neurons. After nerve injury, TrkC expression was also increased in the small DRG cells of allodynic animals (although less than NT3), and the medium- and large-size cells of nonallodynic ones. After RTX, TrkC expression gradually decreased, but with persistence in the large DRG cells. CONCLUSION NT3 may have antinociceptive effects in the DRG. These effects may be mediated, at least in part, by TrkC in the medium- and large-size DRG neurons.
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Affiliation(s)
- Gabriel C Tender
- Department of Neurosurgery, Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Bachy I, Franck MCM, Li L, Abdo H, Pattyn A, Ernfors P. The transcription factor Cux2 marks development of an A-delta sublineage of TrkA sensory neurons. Dev Biol 2011; 360:77-86. [PMID: 21945863 DOI: 10.1016/j.ydbio.2011.09.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 08/25/2011] [Accepted: 09/07/2011] [Indexed: 11/29/2022]
Abstract
The developmental process and unique molecular identity between the many different types of dorsal root ganglion (DRG) sensory neurons generated during embryogenesis provide the cellular basis for the distinct perceptual modalities of somatosensation. The mechanisms leading to the generation of different types of nociceptive sensory neurons remain only partly understood. Here, we show that the transcription factor Cux2 is a novel marker of sensory neuron subpopulations of three main sublineages as defined by the expression of neurotrophic factor receptors TrkA, TrkB and TrkC. In particular, it is expressed in a subpopulation of early TrkA(+) neurons that arise during the early, Ngn1-independent initiated neurogenesis in the DRG. Postnatally, Cux2 marks a specific subtype of A-delta nociceptors as seen by expression of TrkA and NF200 but absence of TrpV1. Analysis of Cux2 mutant mice shows that Cux2 is not required for specification of Trk(+) neuronal subpopulations. However, Cux2 mutant mice are hypersensitive to mechanical, but not to heat or cold stimuli, consistent with a requirement in the process of specification of the mechanoreceptive neuron circuit. Hence, our results show that Cux2 is expressed and may participate in development of a specific subtype of myelinated TrkA(+) nociceptors.
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Affiliation(s)
- Isabelle Bachy
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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Disruption of the transient receptor potential vanilloid 1 can affect survival, bacterial clearance, and cytokine gene expression during murine sepsis. Anesthesiology 2011; 114:1190-9. [PMID: 21383614 DOI: 10.1097/aln.0b013e318212515b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Previous studies suggest that the transient receptor potential vanilloid 1 (TRPV1) channel has a role in sepsis, but it is unclear whether its effect on survival and immune response is beneficial or harmful. METHODS We studied the effects of genetic (Trpv1-knockout vs. wild-type [WT] mice) and pharmacologic disruption of TRPV1 with resiniferatoxin (an agonist) or capsazepine (an antagonist) on mortality, bacterial clearance, and cytokine expression during lipopolysaccharide or cecal ligation and puncture-induced sepsis. RESULTS After cecal ligation and puncture, genetic disruption of TRPV1 in Trpv1-knockout versus WT mice was associated with increased mortality risk (hazard ratio, 2.17; 95% CI, 1.23-3.81; P = 0.01). Furthermore, pharmacologic disruption of TRPV1 with intrathecal resiniferatoxin, compared with vehicle, increased mortality risk (hazard ratio, 1.80; 95% CI, 1.05-3.2; P = 0.03) in WT, but not in Trpv1-knockout, mice. After lipopolysaccharide, neither genetic (Trpv1 knockout) nor pharmacologic disruption of TRPV1 with resiniferatoxin had significant effect on survival compared with respective controls. In contrast, after lipopolysaccharide, pharmacologic disruption of TRPV1 with capsazepine, compared with vehicle, increased mortality risk (hazard ratio, 1.92; 95% CI, 1.02-3.61; P = 0.04) in WT animals. Furthermore, after cecal ligation and puncture, increased mortality in resiniferatoxin-treated WT animals was associated with higher blood bacterial count (P = 0.0004) and higher nitrate/nitrite concentrations and down-regulation of tumor necrosis factor α expression (P = 0.004) compared with controls. CONCLUSIONS Genetic or pharmacologic disruption of TRPV1 can affect mortality, blood bacteria clearance, and cytokine response in sepsis in patterns that may vary according to the sepsis-inducing event and the method of TRPV1 disruption.
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Bishnoi M, Bosgraaf CA, Premkumar LS. Preservation of acute pain and efferent functions following intrathecal resiniferatoxin-induced analgesia in rats. THE JOURNAL OF PAIN 2011; 12:991-1003. [PMID: 21680254 DOI: 10.1016/j.jpain.2011.03.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 01/25/2011] [Accepted: 03/16/2011] [Indexed: 01/29/2023]
Abstract
UNLABELLED Resiniferatoxin (RTX) is a potent agonist of TRPV1, which possesses unique properties that can be utilized to treat certain modalities of pain. In the present study, systemic intraperitoneal (i.p.) administration of RTX resulted in a significant decrease in acute thermal pain sensitivity, whereas localized intrathecal (i.t.) administration had no effect on acute thermal pain sensitivity. Both i.p. and i.t. administration of RTX prevented TRPV1-induced nocifensive behavior and inflammatory thermal hypersensitivity. There were no alterations in mechanical sensitivity either by i.p. or i.t. administration of RTX. In spinal dorsal horn (L4-L6), TRPV1 and substance P immunoreactivity were abolished following i.p. and i.t. administration of RTX. In dorsal root ganglia (DRG), TRPV1 immunoreactivity was diminished following i.p. administration, but was unaffected following i.t. administration of RTX. Following i.p. administration, basal and evoked calcitonin gene-related peptide release were reduced both in the spinal cord and peripheral tissues. However, following i.t. administration, basal and evoked calcitonin gene-related peptide release were reduced in spinal cord (L4-L6), but were unaffected in peripheral tissues. Both i.p. and i.t. RTX administration lowered the body temperature acutely, but this effect reversed with time. Targeting TRPV1-expressing nerve terminals at the spinal cord can selectively abolish inflammatory thermal hypersensitivity without affecting acute thermal sensitivity and can preserve the efferent functions of DRG neurons at the peripheral nerve terminals. I.t. administration of RTX can be considered as a strategy for treating certain chronic and debilitating pain conditions. PERSPECTIVE Localized administration of RTX in spinal cord could be a useful strategy to treat chronic debilitating pain arising from certain conditions such as cancer and at the same time could maintain normal physiological peripheral efferent functions mediated by TRPV1.
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Affiliation(s)
- Mahendra Bishnoi
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62702, 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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Nagy B, Fedonidis C, Photiou A, Wahba J, Paule C, Ma D, Buluwela L, Nagy I. Capsaicin-sensitive primary sensory neurons in the mouse express N-Acyl phosphatidylethanolamine phospholipase D. Neuroscience 2009; 161:572-7. [PMID: 19327387 PMCID: PMC2724038 DOI: 10.1016/j.neuroscience.2009.03.047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 03/17/2009] [Accepted: 03/17/2009] [Indexed: 01/30/2023]
Abstract
Our previous finding, that the capsaicin- and KCl-induced Ca(2+)-dependent production of the intra- and intercellular signaling molecule N-arachidonoyl ethanolamine (anandamide) in cultured primary sensory neurons could be abolished and reduced by approximately 2/3 by capsaicin-induced degeneration of capsaicin-sensitive neurons, respectively suggests that a major sub-population of capsaicin-sensitive cells together with a group of non-capsaicin-sensitive cells should express enzymes involved in Ca(2+)-dependent anandamide synthesis. N-acyl phosphotidylethanolamine phospholipase D (NAPE-PLD) is known to be involved in Ca(2+)-dependent anandamide production. Hence, here, we used reverse transcriptase and quantitative real time polymerase chain reaction to study NAPE-PLD expression in dorsal root ganglia and to clarify the sub-population of cells expressing this enzyme. Cultures prepared from mouse dorsal root ganglia were grown either in the absence or presence of the neurotoxin, capsaicin (10 muM) overnight. We report, that NAPE-PLD is expressed both in dorsal root ganglia and cultures prepared from dorsal root ganglia and grown in the absence of capsaicin. Furthermore, we also report that capsaicin application downregulates the expression of NAPE-PLD as well as the capsaicin receptor, transient receptor potential vanilloid type 1 ion channel, by about 70% in the cultures prepared from dorsal root ganglia. These findings indicate that a major sub-population of capsaicin-sensitive primary sensory neurons expresses NAPE-PLD, and suggest that NAPE-PLD is expressed predominantly by capsaicin-sensitive neurons in dorsal root ganglia. These data also suggest that NAPE-PLD might be a target to control the activity and excitability of a major sub-population of nociceptive primary sensory neurons.
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Key Words
- anandamide
- dorsal root ganglion
- transient receptor vanilloid type 1
- trpv1
- nociceptive
- pain
- anandamide, n-arachidonoyl ethanolamine
- cb1, cannabinoid 1
- cb2, cannabinoid 2
- drg, dorsal root ganglia
- faah, fatty acid amide hydrolase
- gapdh, glyceraldehyde-3-phosphate dehydrogenase
- nape-pld, n-acyl phosphotidylethanolamine phospholipase d
- pcr, polymerase chain reaction
- rt, reverse transcriptase
- trpv1, transient receptor potential vanilloid type 1
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Affiliation(s)
- B. Nagy
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
| | - C. Fedonidis
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
| | - A. Photiou
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
- Department of Oncology, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - J. Wahba
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
| | - C.C. Paule
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
| | - D. Ma
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
| | - L. Buluwela
- Department of Oncology, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - I. Nagy
- Department of Anaesthetics, Pain Medicine and Intensive Care, Imperial College London, Faculty of Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
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Marotta DM, Costa R, Motta EM, Fernandes ES, Medeiros R, Quintão NL, Campos MM, Calixto JB. Mechanisms underlying the nociceptive responses induced by platelet-activating factor (PAF) in the rat paw. Biochem Pharmacol 2009; 77:1223-35. [DOI: 10.1016/j.bcp.2008.12.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
BACKGROUND Use of capsaicin or resiniferatoxin (RTX) as analgesics is an attractive therapeutic option. RTX opens the cation channel inflammatory pain/vanilloid receptor type 1 (TRPV1) permanently and selectively removes nociceptive neurons by Ca(2+)-cytotoxicity. Paradoxically, not only nociceptors, but non-neuronal cells, including keratinocytes express full length TRPV1 mRNA, while patient dogs and experimental animals that underwent topical treatment or anatomically targeted molecular surgery have shown neither obvious behavioral, nor pathological side effects. METHODS To address this paradox, we assessed the vanilloid sensitivity of the HaCaT human keratinocyte cell line and primary keratinocytes from skin biopsies. RESULTS Although both cell types express TRPV1 mRNA, neither responded to vanilloids with Ca(2+)-cytotoxicity. Only ectopic overproduction of TRPV1 rendered HaCaT cells sensitive to low doses (1-50 nM) of vanilloids. The TRPV1-mediated and non-receptor specific Ca(2+)-cytotoxicity ([RTX]>15 microM) could clearly be distinguished, thus keratinocytes were indeed resistant to vanilloid-induced, TRPV1-mediated Ca(2+)-entry. Having a wider therapeutic window than capsaicin, RTX was effective in subnanomolar range, but even micromolar concentrations could not kill human keratinocytes. Keratinocytes showed orders of magnitudes lower TRPV1 mRNA level than sensory ganglions, the bona fide therapeutic targets in human pain management. In addition to TRPV1, TRPV1b, a dominant negative splice variant was also noted in keratinocytes. CONCLUSION TRPV1B expression, together with low TRPV1 expression, may explain the vanilloid paradox: even genuinely TRPV1 mRNA positive cells can be spared with therapeutic (up to micromolar) doses of RTX. This additional safety information might be useful for planning future human clinical trials.
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Roh EJ, Keller JM, Olah Z, Iadarola MJ, Jacobson KA. Structure-activity relationships of 1,4-dihydropyridines that act as enhancers of the vanilloid receptor 1 (TRPV1). Bioorg Med Chem 2008; 16:9349-58. [PMID: 18809334 DOI: 10.1016/j.bmc.2008.08.048] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 08/15/2008] [Accepted: 08/22/2008] [Indexed: 10/21/2022]
Abstract
Vanilloid agonists such as capsaicin activate ion flux through the TRPV1 channel, a heat- and ligand-gated cation channel that transduces painful chemical or thermal stimuli applied to peripheral nerve endings in skin or deep tissues. We have probed the SAR of a variety of 1,4-dihydropyridine (DHP) derivatives as novel 'enhancers' of TRPV1 activity by examining changes in capsaicin-induced elevations in (45)Ca(2+)-uptake in either cells ectopically expressing TRPV1 or in cultured dorsal root ganglion (DRG) neurons. The enhancers increased the maximal capsaicin effect on (45)Ca(2+)-uptake by typically 2- to 3-fold without producing an action when used alone. The DHP enhancers contained 6-aryl substitution and small alkyl groups at the 1 and 4 positions, and a 3-phenylalkylthioester was tolerated. Levels of free intracellular Ca(2+), as measured by calcium imaging, were also increased in DRG neurons when exposed to the combination of capsaicin and the most efficacious enhancer 23 compared to capsaicin alone. Thus, DHPs can modulate TRPV1 channels in a positive fashion.
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Affiliation(s)
- Eun Joo Roh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Building 8A, Room B1A-19 LBC, Bethesda, MD 20892-0810, USA
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Bai ZT, Liu T, Pang XY, Jiang F, Cheng M, Ji YH. Functional depletion of capsaicin-sensitive primary afferent fibers attenuates rat pain-related behaviors and paw edema induced by the venom of scorpion Buthus martensi Karch. Neurosci Res 2008; 62:78-85. [PMID: 18619501 DOI: 10.1016/j.neures.2008.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 06/09/2008] [Accepted: 06/10/2008] [Indexed: 11/25/2022]
Abstract
The role of capsaicin-sensitive primary afferent fibers in rat pain-related behaviors and paw edema induced by scorpion Buthus martensi Karch (BmK) venom was investigated in this study. It was found that functional depletion of capsaicin-sensitive primary afferent fibers with a single systemic injection of resiniferatoxin (RTX) dramatically decreased spontaneous nociceptive behaviors, prevented the development of primary mechanical and thermal hyperalgesia as well as mirror-image mechanical hyperalgesia. RTX treatment significantly attenuated BmK venom-induced c-Fos expression in all laminaes of bilateral L4-L5 lumbar spinal cord, especially in superficial laminaes. Moreover, RTX treatment markedly reduced the early paw edema induced by BmK venom. Thus, the results indicate that capsaicin-sensitive primary afferent fibers play a critical role in various pain-related behaviors and paw edema induced by BmK venom in rats.
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Affiliation(s)
- Zhan-Tao Bai
- College of Life Sciences, Yanan University, Yanan 716000, PR China
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Pharmacologic disruption of TRPV1-expressing primary sensory neurons but not genetic deletion of TRPV1 protects mice against pancreatitis. Pancreas 2008; 36:394-401. [PMID: 18437086 DOI: 10.1097/mpa.0b013e318160222a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Transient receptor potential subtype vanilloid 1 (TRPV1) is an ion channel that is primarily expressed by primary sensory neurons where it mediates pain and heat sensation and participates in neurogenic inflammation. In this study, we examined the role of TRPV1 during neurogenic activation of pancreatic inflammation using a secretagogue-induced model in mice. METHODS A supramaximal dose of caerulein (50 microg/kg) was injected hourly for 12 hours. Mice lacking TRPV1 were compared to wild-type animals. RESULTS All the parameters: serum amylase, pancreatic myeloperoxidase activity, histological scoring, pancreatic wet weight/body weight ratio, and quantification of neurokinin-1 receptor internalization indicated that null mice were not protected from acute pancreatitis. However, when primary sensory neurons were ablated by injection of the neurotoxin and TRPV1 agonist, resiniferatoxin, pancreatitis was ameliorated in wild-type mice but not in null mice, indicating that nerves bearing TRPV1 are part of the inflammatory pathway in acute pancreatitis because disappearance significantly reduced the inflammatory response. CONCLUSIONS Nerves expressing TRPV1 participate in the neurogenic inflammation during acute pancreatitis. The lack of protection in TRPV1 null mice suggests that an alternate pathway to TRPV1 coexists in the same neurons.
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Tender GC, Li YY, Cui JG. Vanilloid receptor 1-positive neurons mediate thermal hyperalgesia and tactile allodynia. Spine J 2008; 8:351-8. [PMID: 18029293 DOI: 10.1016/j.spinee.2007.08.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 04/11/2007] [Accepted: 08/27/2007] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The vanilloid receptor 1 (VR1) is expressed by the type II A-delta and C-fiber neurons, functioning as a molecular integrator for nociception. VR1 can be selectively ablated by resiniferatoxin (RTX), an ultra-potent excitotoxic agonist, when injected into sensory ganglia. PURPOSE To evaluate the role of the VR1-positive neurons in neuropathic pain. STUDY DESIGN Photochemical injury to rat sciatic nerve (Gazelius model). METHODS Two groups of rats underwent the photochemical injury and RTX treatment. RTX was injected in the dorsal root ganglia (DRGs) of the L3, L4, L5, and L6 nerve roots, either after or before the nerve injury. The animals were tested for thermal hyperalgesia (noxious heat stimuli) and mechanical allodynia (von Frey filaments). Immunohistochemical analysis of the DRGs was performed after euthanasia. RESULTS In the tactile allodynic rats, RTX injection in the DRGs improved the average withdrawal threshold from 1.62 g to 5.68 g. Immunohistochemical labeling showed that almost all VR1-positive neurons were eliminated. When RTX was administrated into the ipsilateral DRGs before the nerve injury, this treatment prevented the development of tactile allodynia in 12 out of 14 rats. Immunohistochemical staining revealed that the VR1-positive neurons were eliminated in the rats that did not develop tactile allodynia, whereas they were still present in the allodynic rats. CONCLUSIONS VR1-positive neurons are essential for the development of mechanical allodynia. In rats already exhibiting neuropathic pain, the VR1-positive neurons mediate the most sensitive part of mechanical allodynia. RTX injection in sensory ganglia may represent a novel treatment for neuropathic pain.
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Affiliation(s)
- Gabriel C Tender
- Department of Neurosurgery, Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Gharat LA, Szallasi A. Advances in the design and therapeutic use of capsaicin receptor TRPV1 agonists and antagonists. Expert Opin Ther Pat 2008. [DOI: 10.1517/13543776.18.2.159] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Depletion of capsaicin-sensitive afferents prevents lamina-dependent increases in spinal N-methyl-D-aspartate receptor subunit 1 expression and phosphorylation associated with thermal hyperalgesia in neuropathic rats. Eur J Pain 2007; 12:552-63. [PMID: 17933570 DOI: 10.1016/j.ejpain.2007.09.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 08/17/2007] [Accepted: 09/03/2007] [Indexed: 11/22/2022]
Abstract
Phosphorylation of the N-methyl-D-aspartate (NMDA) receptor NR1 subunit (pNR1) in the spinal cord is associated with increased neuronal responsiveness, which underlies the process of central sensitization. Because of the importance of NR1 in central sensitization, the first goal of this study was to examine both time- and lamina-dependent changes in spinal NR1 and pNR1 expression in a chronic constriction injury (CCI) model of neuropathic pain. Increased excitability of capsaicin sensitive primary afferents (CSPAs), which express TRPV1 receptors, also contributes to central sensitization. Thus, we next examined whether the depletion of CSPAs with resiniferatoxin (RTX) modified the change of spinal NR1 and pNR1 expression induced by CCI. Experimental rats were euthanized at 1, 3, 7, 14, and 28 days post-CCI surgery and spinal cords processed for NR1 or pNR1 immunostaining. The number of NR1 or pNR1-immunoreactive neurons was significantly increased in all lamina (I-VI) of the ipsilateral L4/L5 dorsal horn from 1 or 7 days post-CCI, respectively. Pretreatment with RTX (0.3mg/kg, s.c. in the scruff of the neck or intraplantar) 2 days prior to CCI completely prevented induction of thermal hyperalgesia, but not mechanical allodynia in neuropathic rats. Interestingly, RTX treatment significantly attenuated the CCI-induced upregulation of NR1 and pNR1 in spinal laminae I-II and V-VI, but not laminae III-IV as compared with that of vehicle-treated CCI rats. These findings demonstrate that the increased expression of NR1 and pNR1 in spinal laminae I-II and V-VI is dependent on activation of CSPAs, which ultimately contribute to the development of thermal hyperalgesia in neuropathic rats.
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Intrathecal administration of resiniferatoxin produces analgesia against prostatodynia in rats. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200709020-00013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Oláh Z, Jósvay K, Pecze L, Letoha T, Babai N, Budai D, Otvös F, Szalma S, Vizler C. Anti-calmodulins and tricyclic adjuvants in pain therapy block the TRPV1 channel. PLoS One 2007; 2:e545. [PMID: 17579717 PMCID: PMC1890308 DOI: 10.1371/journal.pone.0000545] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 05/24/2007] [Indexed: 11/18/2022] Open
Abstract
Ca(2+)-loaded calmodulin normally inhibits multiple Ca(2+)-channels upon dangerous elevation of intracellular Ca(2+) and protects cells from Ca(2+)-cytotoxicity, so blocking of calmodulin should theoretically lead to uncontrolled elevation of intracellular Ca(2+). Paradoxically, classical anti-psychotic, anti-calmodulin drugs were noted here to inhibit Ca(2+)-uptake via the vanilloid inducible Ca(2+)-channel/inflamatory pain receptor 1 (TRPV1), which suggests that calmodulin inhibitors may block pore formation and Ca(2+) entry. Functional assays on TRPV1 expressing cells support direct, dose-dependent inhibition of vanilloid-induced (45)Ca(2+)-uptake at microM concentrations: calmidazolium (broad range) > or = trifluoperazine (narrow range) chlorpromazine/amitriptyline>fluphenazine>>W-7 and W-13 (only partially). Most likely a short acidic domain at the pore loop of the channel orifice functions as binding site either for Ca(2+) or anti-calmodulin drugs. Camstatin, a selective peptide blocker of calmodulin, inhibits vanilloid-induced Ca(2+)-uptake in intact TRPV1(+) cells, and suggests an extracellular site of inhibition. TRPV1(+), inflammatory pain-conferring nociceptive neurons from sensory ganglia, were blocked by various anti-psychotic and anti-calmodulin drugs. Among them, calmidazolium, the most effective calmodulin agonist, blocked Ca(2+)-entry by a non-competitive kinetics, affecting the TRPV1 at a different site than the vanilloid binding pocket. Data suggest that various calmodulin antagonists dock to an extracellular site, not found in other Ca(2+)-channels. Calmodulin antagonist-evoked inhibition of TRPV1 and NMDA receptors/Ca(2+)-channels was validated by microiontophoresis of calmidazolium to laminectomised rat monitored with extracellular single unit recordings in vivo. These unexpected findings may explain empirically noted efficacy of clinical pain adjuvant therapy that justify efforts to develop hits into painkillers, selective to sensory Ca(2+)-channels but not affecting motoneurons.
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Affiliation(s)
- Zoltán Oláh
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary; Acheuron Hungary Ltd., Szeged, Hungary; Acheuron Pharmaceuticals Inc., San Diego, California, United States of America.
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Jiang N, Cooper BY, Nemenov MI. Non-invasive diode laser activation of transient receptor potential proteins in nociceptors. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2007; 6428:642809. [PMID: 21709727 PMCID: PMC3122473 DOI: 10.1117/12.699204] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We investigated diode laser (980 nm) evoked activation of transient receptor potential proteins (TRPV1 and TRPV2). C and A-delta (Aδ) nociceptor families are primarily responsible for pain mediation in the peripheral nervous system. TRPV1 proteins have been associated with heat evoked pain in C fibers while Aδ fibers have been associated with TRPV2. Diode laser stimulation allows a margin of safety between non-invasive activation and damage (19, 22, 34). Laser pulses (20-50 ms, 0.1-10 W, 980 nm) were used to stimulate: A) in vitro: excised patches from HEK293 cells expressing TRPV1; B) in vitro: rat DRG nociceptors expressing either TRPV1 or TRPV2; and C) in vivo: C-fibers of the rat saphenous nerve (SN) trunk. Cell currents were recorded using standard patch clamp methods. The SN was also stimulated electrically with bipolar electrodes. Stimulation (20-50 ms) of HEK and DRG cells expressing TRPV1 was highly reproducible. Activation and peak currents were achieved at estimated peak temperatures of 55°C and 70°C. Threshold activation was also observed in DRG neurons expressing TRPV2. The conduction velocity for laser-activated saphenous nerve afferents was in the C fiber range (0.5-1 m/s). Electrically stimulated nerve contained stimulation artifacts and complex neural components with conduction velocities ranging from 0.3-30 m/s. Diode laser activation of TRPV1 protein is a reproducible and effective means to probe TRP activity in both in vivo and in vitro preparations.
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Affiliation(s)
- Nan Jiang
- Dept. of Oral Surgery, University of Florida, Gainesville, FL, USA
| | - Brian Y. Cooper
- Dept. of Oral Surgery, University of Florida, Gainesville, FL, USA
| | - Michael I. Nemenov
- Dept. of Anesthesia, Stanford University, 300 Pasteur Drive, Stanford, CA 94305-5117
- LasMed LLC, Mountain View, CA, USA 94043
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Roh DH, Kim HW, Yoon SY, Kang SY, Kwon YB, Cho KH, Han HJ, Ryu YH, Choi SM, Lee HJ, Beitz AJ, Lee JH. Bee venom injection significantly reduces nociceptive behavior in the mouse formalin test via capsaicin-insensitive afferents. THE JOURNAL OF PAIN 2006; 7:500-12. [PMID: 16814689 DOI: 10.1016/j.jpain.2006.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 02/03/2006] [Accepted: 02/04/2006] [Indexed: 11/29/2022]
Abstract
UNLABELLED Peripheral bee venom (BV) administration produces 2 contrasting effects, nociception and antinociception. This study was designed to evaluate whether the initial nociceptive effect induced by BV injection into the Zusanli acupoint is involved in producing the more prolonged antinociceptive effect observed in the mouse formalin test, and whether capsaicin-sensitive primary afferents are involved in these effects. BV injection into the Zusanli point increased spinal Fos expression but not spontaneous nociceptive behavior. BV pretreatment 10 minutes before intraplantar formalin injection dose-dependently attenuated nociceptive behavior associated with the second phase of the formalin test. The destruction of capsaicin-sensitive primary afferents by resiniferatoxin (RTX) pretreatment selectively decreased BV-induced spinal Fos expression but did not affect BV-induced antinociception. Furthermore, BV injection increased Fos expression in tyrosine hydroxylase immunoreactive neurons in the locus caeruleus, and this expression was unaltered by RTX pretreatment. Finally, BV's antinociception was blocked by intrathecal injection of 10 microg idazoxan, and this effect was not modified by RTX pretreatment. These findings suggest that subcutaneous BV stimulation of the Zusanli point activates central catecholaminergic neurons via capsaicin-insensitive afferent fibers without induction of nociceptive behavior. This in turn leads to the activation of spinal alpha2-adrenoceptors, which ultimately reduces formalin-evoked nociceptive behaviors. PERSPECTIVE This study demonstrates that BV acupuncture produces a significant antinociception without nociceptive behavior in rodents, which is mediated by capsaicin-insensitive afferents and involves activation of central adrenergic circuits. These results further suggest that BV stimulation into this acupuncture point might be a valuable alternative to traditional electrical or mechanical acupoint stimulation.
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Affiliation(s)
- Dae-Hyun Roh
- Department of Veterinary Physiology, College of Veterinary Medicine and School of Agricultural Biotechnology, Seoul National University, Seoul, South Korea
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Diogenes A, Patwardhan AM, Jeske NA, Ruparel NB, Goffin V, Akopian AN, Hargreaves KM. Prolactin modulates TRPV1 in female rat trigeminal sensory neurons. J Neurosci 2006; 26:8126-36. [PMID: 16885226 PMCID: PMC6673790 DOI: 10.1523/jneurosci.0793-06.2006] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sex dependency in pain perception is well documented and is thought to be attributable to the effect of reproductive hormones on nociceptive processing. In the present study, we evaluated whether estradiol alters gene transcription in the trigeminal ganglia (TG) of ovariectomized rats (OVX). These experiments demonstrated a dramatic (40-fold) upregulation of prolactin (PRL) expression in TG by 17-beta-estradiol (E2). PRL expression was restricted to TG neurons and was highly overlapped with transient potential receptor vanilloid type 1 (TRPV1) (approximately 90%) in TG. Additionally, PRL is released from neurons during stimulation. Both forms of PRL receptors (PRLRs), short and long, were also present in TG neurons. Moreover, expression of the long PRLRs was under control of estradiol. We next evaluated the novel hypothesis that PRL acts as a neuromodulator of sensory neurons. PRL pretreatment significantly enhanced capsaicin-evoked inward currents, calcium influx, and immunoreactive calcitonin gene-related peptide release from cultured TG neurons. This PRL modulation of capsaicin responses was abolished by withdrawal of E2 from TG cultures. Biochemical analysis demonstrated that PRL increased (>50%) phosphorylation levels of TRPV1 in TG. In a behavioral test, PRL pretreatment significantly potentiated capsaicin-evoked nocifensive behavior in female rats at proestrous and in OVX rats after E2 treatment. The in vivo potentiating effect of PRL on capsaicin responses was also dependent on E2. Collectively, these data demonstrate that PRL is a novel modulator of sensory neurons tightly regulated by E2. These findings are consistent with the hypothesis that PRL could contribute to the development of certain pain disorders, possibly including those modulated by estrogen.
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Appendino G, Szallasi A. 4 Clinically Useful Vanilloid Receptor TRPV1 Antagonists: Just around the Corner (or too Early to Tell)? PROGRESS IN MEDICINAL CHEMISTRY 2006; 44:145-80. [PMID: 16697897 DOI: 10.1016/s0079-6468(05)44404-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Giovanni Appendino
- Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche e Farmacologiche, Università del Piemonte Orientale, Novara, Italy
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