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Allen D, Zhou Y, Wilhelm A, Blum P. Intracellular G-actin targeting of peripheral sensory neurons by the multifunctional engineered protein C2C confers relief from inflammatory pain. Sci Rep 2020; 10:12789. [PMID: 32732905 PMCID: PMC7393082 DOI: 10.1038/s41598-020-69612-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/15/2020] [Indexed: 11/09/2022] Open
Abstract
The engineered multifunctional protein C2C was tested for control of sensory neuron activity by targeted G-actin modification. C2C consists of the heptameric oligomer, C2II-CI, and the monomeric ribosylase, C2I. C2C treatment of sensory neurons and SH-SY5Y cells in vitro remodeled actin and reduced calcium influx in a reversible manner. C2C prepared using fluorescently labeled C2I showed selective in vitro C2I delivery to primary sensory neurons but not motor neurons. Delivery was dependent on presence of both C2C subunits and blocked by receptor competition. Immunohistochemistry of mice treated subcutaneously with C2C showed colocalization of subunit C2I with CGRP-positive sensory neurons and fibers but not with ChAT-positive motor neurons and fibers. The significance of sensory neuron targeting was pursued subsequently by testing C2C activity in the formalin inflammatory mouse pain model. Subcutaneous C2C administration reduced pain-like behaviors by 90% relative to untreated controls 6 h post treatment and similarly to the opioid buprenorphene. C2C effects were dose dependent, equally potent in female and male animals and did not change gross motor function. One dose was effective in 2 h and lasted 1 week. Administration of C2I without C2II-CI did not reduce pain-like behavior indicating its intracellular delivery was required for behavioral effect.
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Affiliation(s)
- Derek Allen
- School of Biological Sciences, University of Nebraska, E234 Beadle Center, Lincoln, NE, 68588, USA
| | - You Zhou
- Center for Biotechnology, University of Nebraska, E234 Beadle Center, Lincoln, NE, 68588, USA
| | - Audrey Wilhelm
- School of Biological Sciences, University of Nebraska, E234 Beadle Center, Lincoln, NE, 68588, USA
| | - Paul Blum
- School of Biological Sciences, University of Nebraska, E234 Beadle Center, Lincoln, NE, 68588, USA.
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2
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Vicario N, Turnaturi R, Spitale FM, Torrisi F, Zappalà A, Gulino R, Pasquinucci L, Chiechio S, Parenti C, Parenti R. Intercellular communication and ion channels in neuropathic pain chronicization. Inflamm Res 2020; 69:841-850. [PMID: 32533221 DOI: 10.1007/s00011-020-01363-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Neuropathic pain is caused by primary lesion or dysfunction of either peripheral or central nervous system. Due to its complex pathogenesis, often related to a number of comorbidities, such as cancer, neurodegenerative and neurovascular diseases, neuropathic pain still represents an unmet clinical need, lacking long-term effective treatment and complex case-by-case approach. AIM AND METHODS We analyzed the recent literature on the role of selective voltage-sensitive sodium, calcium and potassium permeable channels and non-selective gap junctions (GJs) and hemichannels (HCs) in establishing and maintaining chronic neuropathic conditions. We finally focussed our review on the role of extracellular microenvironment modifications induced by resident glial cells and on the recent advances in cell-to-cell and cell-to-extracellular environment communication in chronic neuropathies. CONCLUSION In this review, we provide an update on the current knowledge of neuropathy chronicization processes with a focus on both neuronal and glial ion channels, as well as on channel-mediated intercellular communication.
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Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rita Turnaturi
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Federica Maria Spitale
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Torrisi
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Lorella Pasquinucci
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Santina Chiechio
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy
- Oasi Research Institute IRCCS, Troina, Italy
| | - Carmela Parenti
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy.
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.
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3
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Bulleyaconitine A Inhibits Visceral Nociception and Spinal Synaptic Plasticity through Stimulation of Microglial Release of Dynorphin A. Neural Plast 2020; 2020:1484087. [PMID: 32565774 PMCID: PMC7262664 DOI: 10.1155/2020/1484087] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/14/2020] [Accepted: 03/11/2020] [Indexed: 12/20/2022] Open
Abstract
Background Visceral pain is one of the most common types of pain and particularly in the abdomen is associated with gastrointestinal diseases. Bulleyaconitine A (BAA), isolated from Aconitum bulleyanum, is prescribed in China to treat chronic pain. The present study is aimed at evaluating the mechanisms underlying BAA visceral antinociception. Methods The rat model of chronic visceral hypersensitivity was set up by colonic perfusion of 2,4,6-trinitrobenzene sulfonic acid (TNBS) on postnatal day 10 with coapplication of heterotypic intermittent chronic stress (HeICS). Results The rat model of chronic visceral hypersensitivity exhibited remarkable abdominal withdrawal responses and mechanical hyperalgesia in hind paws, which were dose-dependently attenuated by single subcutaneous of administration of BAA (30 and 90 μg/kg). Pretreatment with the microglial inhibitor minocycline, dynorphin A antiserum, and κ-opioid receptor antagonist totally blocked BAA-induced visceral antinociception and mechanical antihyperalgesia. Spontaneous excitatory postsynaptic currents (sEPSCs) in spinal dorsal horn lamina II neurons were recorded by using whole-cell patch clamp. Its frequency (but not amplitude) from TNBS-treated rats was remarkably higher than that from naïve rats. BAA (1 μM) significantly reduced the frequency of sEPSCs from TNBS-treated rats but not naïve rats. BAA-inhibited spinal synaptic plasticity was blocked by minocycline, the dynorphin A antiserum, and κ-opioid receptor antagonist. Dynorphin A also inhibited spinal synaptic plasticity in a κ-opioid receptor-dependent manner. Conclusions These results suggest that BAA produces visceral antinociception by stimulating spinal microglial release of dynorphin A, which activates presynaptic κ-opioid receptors in afferent neurons and inhibits spinal synaptic plasticity, highlighting a novel interaction mode between microglia and neurons.
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Huang SN, Yang B, Ma L, Huang LT, Ju PJ, Wei J, Ali U, Wang YX, Chen J. Bulleyaconitine A Exerts Antianxiety and Antivisceral Hypersensitivity Effects. Front Pharmacol 2020; 11:328. [PMID: 32265706 PMCID: PMC7098429 DOI: 10.3389/fphar.2020.00328] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Visceral pain is one of the leading causes for abdominal pain in gastroenterological diseases and is still hard to treat effectively. Bulleyaconitine A (BAA) is an aconitine analog and has been used for the treatment of pain. Our previous work suggested that BAA exerted analgesic effects on neuropathic pain through stimulating the expression of dynorphin A in spinal microglia. Here, we investigated the inhibitory effect of BAA on visceral pain and examined whether the expression of dynorphin A in spinal microglia was responsible for its effects. We found that BAA produced significant antivisceral pain effect induced by acetic acid through stimulating dynorphin A expression in spinal microglia. In addition, anxiety and chronic visceral pain are highly prevalent comorbid conditions in clinical research, which is still a problem to be solved. We also aimed to evaluate the effects of BAA on anxiety. A comorbidity model with characteristics of both chronic visceral pain and anxiety was developed by colorectal injection of 2,4,6-trinitrobenzene sulfonic acid and the induction of heterotypic intermittent chronic stress protocol. In comorbid animals, BAA exerted great antianxiety effects. Meanwhile, the antianxiety mechanism of BAA was different with the antivisceral pain mechanism of BAA. In conclusion, our study demonstrated, for the first time, that BAA exerted marked antivisceral pain and antianxiety effects, which expands the analgesic spectrum and clinical application of BAA. Furthermore, it also it provides a better guidance for the clinical use of BAA.
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Affiliation(s)
- Sheng-Nan Huang
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China.,Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - BeiBei Yang
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China
| | - Le Ma
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China.,Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Lan-Ting Huang
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China
| | - Pei-Jun Ju
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China
| | - Jinbao Wei
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China.,Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Usman Ali
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China.,Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Yong-Xiang Wang
- Shanghai Jiao Tong University School of Pharmacy, Shanghai, China
| | - Jinghong Chen
- Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai, China
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5
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Ma RSY, Kayani K, Whyte-Oshodi D, Whyte-Oshodi A, Nachiappan N, Gnanarajah S, Mohammed R. Voltage gated sodium channels as therapeutic targets for chronic pain. J Pain Res 2019; 12:2709-2722. [PMID: 31564962 PMCID: PMC6743634 DOI: 10.2147/jpr.s207610] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 08/02/2019] [Indexed: 01/23/2023] Open
Abstract
Being maladaptive and frequently unresponsive to pharmacotherapy, chronic pain presents a major unmet clinical need. While an intact central nervous system is required for conscious pain perception, nociceptor hyperexcitability induced by nerve injury in the peripheral nervous system (PNS) is sufficient and necessary to initiate and maintain neuropathic pain. The genesis and propagation of action potentials is dependent on voltage-gated sodium channels, in particular, Nav1.7, Nav1.8 and Nav1.9. However, nerve injury triggers changes in their distribution, expression and/or biophysical properties, leading to aberrant excitability. Most existing treatment for pain relief acts through non-selective, state-dependent sodium channel blockage and have narrow therapeutic windows. Natural toxins and developing subtype-specific and molecular-specific sodium channel blockers show promise for treatment of neuropathic pain with minimal side effects. New approaches to analgesia include combination therapy and gene therapy. Here, we review how individual sodium channel subtypes contribute to pain, and the attempts made to develop more effective analgesics for the treatment of chronic pain.
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Affiliation(s)
- Renee Siu Yu Ma
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Kayani Kayani
- Department of Medicine, University of Cambridge, Cambridge, UK
| | | | | | | | | | - Raihan Mohammed
- Department of Medicine, University of Cambridge, Cambridge, UK
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6
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Aljonaieh KI. Effect of intravenous lidocaine on the incidence of postextubation laryngospasm: A double-blind, placebo-controlled randomized trial. Saudi J Anaesth 2018; 12:3-9. [PMID: 29416449 PMCID: PMC5789503 DOI: 10.4103/sja.sja_440_17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Objectives The study aimed to test the effect of intraoperative intravenous (IV) lidocaine on the incidence of postextubation laryngospasm in adult patients. Methods The prospective randomized clinical trial was conducted at tertiary care hospital in Riyadh, between January and December 2012. Seventy-two patients undergoing laparoscopic cholecystectomy were randomly assigned to receive either placebo (n = 36) or IV lidocaine (n = 36), 1 mg/kg bolus after desflurane was discontinued. Laryngospasm was graded from 0 to 3 based on the absence or presence of signs and the severity of postextubation laryngospasm. Results The study was terminated early by the data monitoring committee because of safety concerns due to an increased incidence of postextubation laryngospasm. Patient demographics were similar for both groups. The incidence of postextubation laryngospasm was 19.5% in the placebo group and 0% in the treatment (lidocaine) group; this difference was statistically significant (P = 0.017; 95% confidence interval, 4.6% to 36.0%). Conclusions The cause of laryngospasm in our study was most likely the rapid increase in the concentration of inspired desflurane, which might have caused airway irritation. Therefore, we believe that pretreating patients at risk of developing laryngospasm with IV lidocaine could be effective.
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Affiliation(s)
- Khalid Ibrahim Aljonaieh
- Department of Anesthesia, College of Medicine, King Khalid University Hospital, King Saud University, Riyadh, Kingdom of Saudi Arabia
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7
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Mule NK, Singh JN, Shah KU, Gulati A, Sharma SS. Endothelin-1 Decreases Excitability of the Dorsal Root Ganglion Neurons via ET B Receptor. Mol Neurobiol 2017. [PMID: 28623618 DOI: 10.1007/s12035-017-0640-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Endothelin-1 (ET-1) has been demonstrated to be a pro-nociceptive as well as an anti-nociceptive agent. However, underlying molecular mechanisms for these pain modulatory actions remain unclear. In the present study, we evaluated the ability of ET-1 to alter the nociceptor excitability using a patch clamp technique in acutely dissociated rat dorsal root ganglion (DRG) neurons. ET-1 produced an increase in threshold current to evoke an action potential (I threshold) and hyperpolarization of resting membrane potential (RMP) indicating decreased excitability of DRG neurons. I threshold increased from 0.25 ± 0.08 to 0.33 ± 0.07 nA and hyperpolarized RMP from -57.51 ± 1.70 to -67.41 ± 2.92 mV by ET-1 (100 nM). The hyperpolarizing effect of ET-1 appears to be orchestrated via modulation of membrane conductances, namely voltage-gated sodium current (I Na) and outward transient potassium current (I KT). ET-1, 30 and 100 nM, decreased the peak I Na by 41.3 ± 6.8 and 74 ± 15.2%, respectively. Additionally, ET-1 (100 nM) significantly potentiated the transient component (I KT) of the potassium currents. ET-1-induced effects were largely attenuated by BQ-788, a selective ETBR blocker. However, a selective ETAR blocker BQ-123 did not alter the effects of ET-1. A selective ETBR agonist, IRL-1620, mimicked the effect of ET-1 on I Na in a concentration-dependent manner (IC50 159.5 ± 92.6 μM). In conclusion, our results demonstrate that ET-1 hyperpolarizes nociceptors by blocking I Na and potentiating I KT through selective activation of ETBR, which may represent one of the underlying mechanisms for reported anti-nociceptive effects of ET-1.
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Affiliation(s)
- Nandkishor K Mule
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India
| | - Jitendra N Singh
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India.
| | - Kunal U Shah
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India
| | - Anil Gulati
- Department of Pharmaceutical Sciences, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, 60515, USA
| | - Shyam S Sharma
- Electrophysiology Laboratory, Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab, 160062, India.
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8
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Kornecook TJ, Yin R, Altmann S, Be X, Berry V, Ilch CP, Jarosh M, Johnson D, Lee JH, Lehto SG, Ligutti J, Liu D, Luther J, Matson D, Ortuno D, Roberts J, Taborn K, Wang J, Weiss MM, Yu V, Zhu DXD, Fremeau RT, Moyer BD. Pharmacologic Characterization of AMG8379, a Potent and Selective Small Molecule Sulfonamide Antagonist of the Voltage-Gated Sodium Channel NaV1.7. J Pharmacol Exp Ther 2017; 362:146-160. [DOI: 10.1124/jpet.116.239590] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/03/2017] [Indexed: 02/05/2023] Open
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9
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Zeng L, Alongkronrusmee D, van Rijn RM. An integrated perspective on diabetic, alcoholic, and drug-induced neuropathy, etiology, and treatment in the US. J Pain Res 2017; 10:219-228. [PMID: 28176937 PMCID: PMC5268333 DOI: 10.2147/jpr.s125987] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neuropathic pain (NeuP) is a syndrome that results from damaged nerves and/or aberrant regeneration. Common etiologies of neuropathy include chronic illnesses and medication use. Chronic disorders, such as diabetes and alcoholism, can cause neuronal injury and consequently NeuP. Certain medications with antineoplastic effects also carry an exquisitely high risk for neuropathy. These culprits are a few of many that are fueling the NeuP epidemic, which currently affects 7%-10% of the population. It has been estimated that approximately 10% and 7% of US adults carry a diagnosis of diabetes and alcohol disorder, respectively. Despite its pervasiveness, many physicians are unfamiliar with adequate treatment of NeuP, partly due to the few reviews that are available that have integrated basic science and clinical practice. In light of the recent Centers for Disease Control and Prevention guidelines that advise against the routine use of μ-opioid receptor-selective opioids for chronic pain management, such a review is timely. Here, we provide a succinct overview of the etiology and treatment options of diabetic and alcohol- and drug-induced neuropathy, three different and prevalent neuropathies fusing the combined clinical and preclinical pharmacological expertise in NeuP of the authors. We discuss the anatomy of pain and pain transmission, with special attention to key ion channels, receptors, and neurotransmitters. An understanding of pain neurophysiology will lead to a better understanding of the rationale for the effectiveness of current treatment options, and may lead to better diagnostic tools to help distinguish types of neuropathy. We close with a discussion of ongoing research efforts to develop additional treatments for NeuP.
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Affiliation(s)
- Lily Zeng
- Department of Internal Medicine, Vanderbilt University Medical Center, Nashville, TN
| | - Doungkamol Alongkronrusmee
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
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10
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Li TF, Fan H, Wang YX. Aconitum-Derived Bulleyaconitine A Exhibits Antihypersensitivity Through Direct Stimulating Dynorphin A Expression in Spinal Microglia. THE JOURNAL OF PAIN 2016; 17:530-48. [DOI: 10.1016/j.jpain.2015.12.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 12/10/2015] [Accepted: 12/22/2015] [Indexed: 12/14/2022]
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11
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Gupta B, Chakraborty S, Saha S, Chandel SG, Baranwal AK, Banerjee M, Chatterjee M, Chaudhury A. Antinociceptive properties of shikonin: in vitro and in vivo studies. Can J Physiol Pharmacol 2016; 94:788-96. [PMID: 27223482 DOI: 10.1139/cjpp-2015-0465] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Shikonin possess a diverse spectrum of pharmacological properties in multiple therapeutic areas. However, the nociceptive effect of shikonin is not largely known. To investigate the antinociceptive potential of shikonin, panel of GPCRs, ion channels, and enzymes involved in pain pathogenesis were studied. To evaluate the translation of shikonin efficacy in vivo, it was tested in 3 established rat pain models. Our study reveals that shikonin has significant inhibitory effect on pan sodium channel/N1E115 and NaV1.7 channel with half maximal inhibitory concentration (IC50) value of 7.6 μmol/L and 6.4 μmol/L, respectively, in a cell-based assay. Shikonin exerted significant dose dependent antinociceptive activity at doses of 0.08%, 0.05%, and 0.02% w/v in pinch pain model. In mechanical hyperalgesia model, dose of 10 and 3 mg/kg (intraperitoneal) produced dose-dependent analgesia and showed 67% and 35% reversal of hyperalgesia respectively at 0.5 h. Following oral administration, it showed 39% reversal at 30 mg/kg dose. When tested in first phase of formalin induced pain, shikonin at 10 mg/kg dose inhibited paw flinching by ∼71%. In all studied preclinical models, analgesic effect was similar or better than standard analgesic drugs. The present study unveils the mechanistic role of shikonin on pain modulation, predominantly via sodium channel modulation, suggesting that shikonin could be developed as a potential pain blocker.
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Affiliation(s)
- Bhawana Gupta
- a Department of Bio and Nano Technology, Bio and Nano Technology Centre, Guru Jambheshwar University of Science and Technology, Hisar 125 001 (Haryana), India.,b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Sabyasachi Chakraborty
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Soumya Saha
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Sunita Gulabsingh Chandel
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Atul Kumar Baranwal
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Manish Banerjee
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Mousumi Chatterjee
- b TCG Life Sciences Private Ltd., R&D Centre Biology, Bengal Intelligent Park Ltd., Block EP and GP, Sector V, Salt Lake, Kolkata 700091 (West Bengal), India
| | - Ashok Chaudhury
- a Department of Bio and Nano Technology, Bio and Nano Technology Centre, Guru Jambheshwar University of Science and Technology, Hisar 125 001 (Haryana), India
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Gualdani R, Tadini-Buoninsegni F, Roselli M, Defrenza I, Contino M, Colabufo NA, Lentini G. Inhibition of hERG potassium channel by the antiarrhythmic agent mexiletine and its metabolite m-hydroxymexiletine. Pharmacol Res Perspect 2015; 3:e00160. [PMID: 26516576 PMCID: PMC4618635 DOI: 10.1002/prp2.160] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 06/04/2015] [Indexed: 02/05/2023] Open
Abstract
Mexiletine is a sodium channel blocker, primarily used in the treatment of ventricular arrhythmias. Moreover, recent studies have demonstrated its therapeutic value to treat myotonic syndromes and to relieve neuropathic pain. The present study aims at investigating the direct blockade of hERG potassium channel by mexiletine and its metabolite m-hydroxymexiletine (MHM). Our data show that mexiletine inhibits hERG in a time- and voltage-dependent manner, with an IC50 of 3.7 ± 0.7 μmol/L. Analysis of the initial onset of current inhibition during a depolarizing test pulse indicates mexiletine binds preferentially to the open state of the hERG channel. Looking for a possible mexiletine alternative, we show that m-hydroxymexiletine (MHM), a minor mexiletine metabolite recently reported to be as active as the parent compound in an arrhythmia animal model, is a weaker hERG channel blocker, compared to mexiletine (IC50 = 22.4 ± 1.2 μmol/L). The hERG aromatic residues located in the S6 helix (Tyr652 and Phe656) are crucial in the binding of mexiletine and the different affinities of mexiletine and MHM with hERG channel are interpreted by modeling their corresponding binding interactions through ab initio calculations. The simulations demonstrate that the introduction of a hydroxyl group on the meta-position of the aromatic portion of mexiletine weakens the interaction of the drug xylyloxy moiety with Tyr652. These results provide further insights into the molecular basis of drug/hERG interactions and, in agreement with previously reported results on clofilium and ibutilide analogs, support the possibility of reducing hERG potency and related toxicity by modifying the aromatic pattern of substitution of clinically relevant compounds.
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Affiliation(s)
- Roberta Gualdani
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze via della Lastruccia 3, Sesto Fiorentino, FI, 50019, Italy
| | - Francesco Tadini-Buoninsegni
- Dipartimento di Chimica "Ugo Schiff", Università di Firenze via della Lastruccia 3, Sesto Fiorentino, FI, 50019, Italy
| | - Mariagrazia Roselli
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Ivana Defrenza
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Marialessandra Contino
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Nicola Antonio Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
| | - Giovanni Lentini
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari "A. Moro" via Orabona 4, Bari, 70125, Italy
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An Introduction to Pain Pathways and Pain “Targets”. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 131:1-30. [DOI: 10.1016/bs.pmbts.2015.01.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Cummins TR, Rush AM. Voltage-gated sodium channel blockers for the treatment of neuropathic pain. Expert Rev Neurother 2014; 7:1597-612. [DOI: 10.1586/14737175.7.11.1597] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Eijkelkamp N, Linley JE, Baker MD, Minett MS, Cregg R, Werdehausen R, Rugiero F, Wood JN. Neurological perspectives on voltage-gated sodium channels. Brain 2012; 135:2585-612. [PMID: 22961543 PMCID: PMC3437034 DOI: 10.1093/brain/aws225] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The activity of voltage-gated sodium channels has long been linked to disorders of neuronal excitability such as epilepsy and chronic pain. Recent genetic studies have now expanded the role of sodium channels in health and disease, to include autism, migraine, multiple sclerosis, cancer as well as muscle and immune system disorders. Transgenic mouse models have proved useful in understanding the physiological role of individual sodium channels, and there has been significant progress in the development of subtype selective inhibitors of sodium channels. This review will outline the functions and roles of specific sodium channels in electrical signalling and disease, focusing on neurological aspects. We also discuss recent advances in the development of selective sodium channel inhibitors.
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Affiliation(s)
- Niels Eijkelkamp
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
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16
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Nardi A, Damann N, Hertrampf T, Kless A. Advances in targeting voltage-gated sodium channels with small molecules. ChemMedChem 2012; 7:1712-40. [PMID: 22945552 DOI: 10.1002/cmdc.201200298] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 07/30/2012] [Indexed: 12/19/2022]
Abstract
Blockade of voltage-gated sodium channels (VGSCs) has been used successfully in the clinic to enable control of pathological firing patterns that occur in conditions as diverse as chronic pain, epilepsy, and arrhythmias. Herein we review the state of the art in marketed sodium channel inhibitors, including a brief compendium of their binding sites and of the cellular and molecular biology of sodium channels. Despite the preferential action of this drug class toward over-excited cells, which significantly limits potential undesired side effects on other cells, the need to develop a second generation of sodium channel inhibitors to overcome their critical clinical shortcomings is apparent. Current approaches in drug discovery to deliver novel and truly innovative sodium channel inhibitors is next presented by surveying the most recent medicinal chemistry breakthroughs in the field of small molecules and developments in automated patch-clamp platforms. Various strategies aimed at identifying small molecules that target either particular isoforms of sodium channels involved in specific diseases or anomalous sodium channel currents, irrespective of the isoform by which they have been generated, are critically discussed and revised.
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Affiliation(s)
- Antonio Nardi
- Global Drug Discovery, Department of Medicinal Chemistry, Grünenthal, Zieglerstrasse 6, 52078 Aachen, Germany.
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17
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Silva AO, Peigneur S, Diniz MRV, Tytgat J, Beirão PSL. Inhibitory effect of the recombinant Phoneutria nigriventer Tx1 toxin on voltage-gated sodium channels. Biochimie 2012; 94:2756-63. [PMID: 22968173 DOI: 10.1016/j.biochi.2012.08.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2012] [Accepted: 08/20/2012] [Indexed: 11/19/2022]
Abstract
Phoneutria nigriventer toxin Tx1 (PnTx1, also referred to in the literature as Tx1) exerts inhibitory effect on neuronal (Na(V)1.2) sodium channels in a way dependent on the holding potential, and competes with μ-conotoxins but not with tetrodotoxin for their binding sites. In the present study we investigated the electrophysiological properties of the recombinant toxin (rPnTx1), which has the complete amino acid sequence of the natural toxin with 3 additional residues: AM on the N-terminal and G on the C-terminal. At the concentration of 1.5 μM, the recombinant toxin inhibits Na(+) currents of dorsal root ganglia neurons (38.4 ± 6.1% inhibition at -80 mV holding potential) and tetrodotoxin-resistant Na(+) currents (26.2 ± 4.9% at the same holding potential). At -50 mV holding potential the inhibition of the total current reached 71.3 ± 2.3% with 1.5 μM rPnTx1. The selectivity of rPnTx1 was investigated on ten different isoforms of voltage-gated sodium channels expressed in Xenopus oocytes. The order of potency for rPnTx1 was: rNa(V)1.2 > rNa(V)1.7 ≈ rNa(V)1.4 ≥ rNa(V)1.3 > mNa(V)1.6 ≥ hNa(V)1.8. No effect was seen on hNa(V)1.5 and on the arthropods isoforms (DmNa(V)1, BGNa(V)1.1a and VdNa(V)1). The IC(50) for Na(V)1.2 was 33.7 ± 2.9 nM with a maximum inhibition of 83.3 ± 1.9%. The toxin did not alter the voltage-dependence of channel gating and was effective on Na(V)1.2 channels devoid of inactivation. It was ineffective on neuronal calcium channels. We conclude that rPnTx1 has a promising selectivity, and that it may be a valuable model to achieve pharmacological activities of interest for the treatment of channelopathies and neuropathic pain.
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Affiliation(s)
- Anita O Silva
- Dept. of Biochemistry and Immunology, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais - UFMG, Av. Antonio Carlos 6627, 31270-901 Belo Horizonte, MG, Brazil
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18
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Nickel FT, Seifert F, Lanz S, Maihöfner C. Mechanisms of neuropathic pain. Eur Neuropsychopharmacol 2012; 22:81-91. [PMID: 21672666 DOI: 10.1016/j.euroneuro.2011.05.005] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 04/12/2011] [Accepted: 05/14/2011] [Indexed: 12/14/2022]
Abstract
Neuropathic pain is a disease of global burden. Its symptoms include spontaneous and stimulus-evoked painful sensations. Several maladaptive mechanisms underlying these symptoms have been elucidated in recent years: peripheral sensitization of nociception, abnormal excitability of afferent neurons, central sensitization comprising pronociceptive facilitation, disinhibition of nociception and central reorganization processes, and sympathetically maintained pain. This review aims to illustrate these pathophysiological principles, focussing on molecular and neurophysiological findings. Finally therapeutic options based on these findings are discussed.
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Affiliation(s)
- Florian T Nickel
- Department of Neurology, University of Erlangen-Nuremberg, Germany
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19
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Schuelert N, McDougall JJ. Involvement of Nav 1.8 sodium ion channels in the transduction of mechanical pain in a rodent model of osteoarthritis. Arthritis Res Ther 2012; 14:R5. [PMID: 22225591 PMCID: PMC3392791 DOI: 10.1186/ar3553] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 12/16/2011] [Accepted: 01/07/2012] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION A subgroup of voltage gated sodium channels including Nav1.8 are exclusively expressed on small diameter primary afferent neurons and are therefore believed to be integral to the neurotransmission of nociceptive pain. The present study examined whether local application of A-803467, a selective blocker of the Nav 1.8 sodium channel, can reduce nociceptive transmission from the joint in a rodent model of osteoarthritis (OA). METHODS OA-like changes were induced in male Wistar rats by an intra-articular injection of 3 mg sodium monoiodoacetate (MIA). Joint nociception was measured at day 14 by recording electrophysiologically from knee joint primary afferents in response to non-noxious and noxious rotation of the joint both before and following close intra-arterial injection of A-803467. The effect of Nav1.8 blockade on joint pain perception and secondary allodynia were determined in MIA treated animals by hindlimb incapacitance and von Frey hair algesiometry respectively. RESULTS A-803467 significantly reduced the firing rate of joint afferents during noxious rotation of the joint but had no effect during non-noxious rotation. In the pain studies, peripheral injection of A-803467 into OA knees attenuated hindlimb incapacitance and secondary allodynia. CONCLUSIONS These studies show for the first time that the Nav1.8 sodium channel is part of the molecular machinery involved in mechanotransduction of joint pain. Targeting the Nav1.8 sodium channel on joint nociceptors could therefore be useful for the treatment of OA pain, avoiding the unwanted side effects of non-selective nerve blocks.
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Affiliation(s)
- Niklas Schuelert
- Department of Physiology & Pharmacology, University of Calgary, 3330, Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
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20
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Tyagarajan S, Chakravarty PK, Zhou B, Taylor B, Eid R, Fisher MH, Parsons WH, Wyvratt MJ, Lyons KA, Klatt T, Li X, Kumar S, Williams B, Felix J, Priest BT, Brochu RM, Warren V, Smith M, Garcia M, Kaczorowski GJ, Martin WJ, Abbadie C, McGowan E, Jochnowitz N, Weber A, Duffy JL. Discovery of a novel class of biphenyl pyrazole sodium channel blockers for treatment of neuropathic pain. Bioorg Med Chem Lett 2010; 20:7479-82. [PMID: 21106456 DOI: 10.1016/j.bmcl.2010.10.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 01/16/2023]
Abstract
A series of novel biphenyl pyrazole dicarboxamides were identified as potential sodium channel blockers for treatment of neuropathic pain. Compound 20 had outstanding efficacy in the Chung rat spinal nerve ligation (SNL) model of neuropathic pain.
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Affiliation(s)
- Sriram Tyagarajan
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065, USA.
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21
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A-887826 is a structurally novel, potent and voltage-dependent Nav1.8 sodium channel blocker that attenuates neuropathic tactile allodynia in rats. Neuropharmacology 2010; 59:201-7. [DOI: 10.1016/j.neuropharm.2010.05.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 05/19/2010] [Accepted: 05/23/2010] [Indexed: 12/19/2022]
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22
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Lenkey N, Karoly R, Epresi N, Vizi E, Mike A. Binding of sodium channel inhibitors to hyperpolarized and depolarized conformations of the channel. Neuropharmacology 2010; 60:191-200. [PMID: 20713065 DOI: 10.1016/j.neuropharm.2010.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/23/2010] [Accepted: 08/07/2010] [Indexed: 12/13/2022]
Abstract
Sodium channels are inhibited by a chemically diverse group of compounds. In the last decade entirely new structural classes with superior properties have been discovered, and novel therapeutic uses of sodium channel inhibitors (SCIs) have been suggested. Many promising novel drug candidates have been described and characterized. Published structure-activity relationship studies, pharmacophore models, and mutagenesis studies seem to lag behind, dealing with only a limited group of inhibitor compounds. The abundance of novel compounds requires an organized comparison of drug potencies. The affinity of sodium channel inhibitors can vary typically ten- to thousand-fold depending on the voltage protocol; therefore comparison of electrophysiology data is difficult. In this study we describe a method for standardization of these data with the help of a simple model of state-dependence. We derived hyperpolarized (resting) and depolarized (generally termed "inactivated") state affinities for the studied drugs, which made the measurements comparable. We show a rank order of SCIs based on resting and inactivated affinity values. In an attempt to define basic chemical requirements for sodium channel inhibitor activity we investigated the dependence of both resting and inactivated state affinities on individual chemical descriptors. Lipophilicity (most often expressed by the logP value) is the single most important determinant of SCI potency. We investigated the independent impact of several other calculated chemical properties by standardizing drug potencies for logP values. By combining these two approaches: standardization of affinity values, and standardization of potencies, we concluded that while resting affinity is mostly determined by lipophilicity, inactivated state affinity is determined by a more complex interaction of chemical properties, including hydrogen bond acceptors, aromatic rings, and molecular weight.
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Affiliation(s)
- N Lenkey
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O.B. 67, H-1450 Budapest, Hungary
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23
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Abstract
Neuropathic pain, a severe chronic pain condition characterized by a complex pathophysiology, is a largely unmet medical need. Ion channels, which underlie cell excitability, are heavily implicated in the biological mechanisms that generate and sustain neuropathic pain. This review highlights the biological evidence supporting the involvement of voltage-, proton- and ligand-gated ion channels in the neuropathic pain setting. Ion channel modulators at different research or development stages are reviewed and referenced. Ion channel modulation is one of the main avenues to achieve novel, improved neuropathic pain treatments. Voltage-gated sodium and calcium channel and glutamate receptor modulators are likely to produce new, improved agents in the future. Rationally targeting subtypes of known ion channels, tackling recently discovered ion channel targets or combining drugs with different mechanism of action will be primary sources of new drugs in the longer term.
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Abstract
Drugs inhibiting voltage-gated sodium channels have long been used as analgesics, beginning with the use of local anaesthetics for sensory blockade and then with the discovery that Nav-blocking anticonvulsants also have benefit for pain therapy. These drugs were discovered without knowledge of their molecular target, using traditional pharmacological methods, and their clinical utility is limited by relatively narrow therapeutic windows. Until recently, attempts to develop improved inhibitors using modern molecular-targeted screening approaches have met with limited success. However, in the last few years there has been renewed activity following the discovery of human Nav1.7 mutations that cause striking insensitivity to pain. Together with recent advances in the technologies required to prosecute ion channels as drug targets, this has led to significant progress being made. This article reviews these developments and summarises current findings with these emerging new Nav inhibitors, highlighting some of the unanswered questions and the challenges that remain before they can be developed for clinical use.
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Affiliation(s)
- Jeffrey J Clare
- Cell-Based Assays Group, Millipore Corporation, St Charles, Missouri 63304, USA.
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25
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Kemp MI. Structural trends among second-generation voltage-gated sodium channel blockers. PROGRESS IN MEDICINAL CHEMISTRY 2010; 49:81-111. [PMID: 20855039 DOI: 10.1016/s0079-6468(10)49003-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Mark I Kemp
- Pfizer Global Research & Development, Sandwich, Kent, UK
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26
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Discovery of a novel class of isoxazoline voltage gated sodium channel blockers. Bioorg Med Chem Lett 2009; 19:5329-33. [DOI: 10.1016/j.bmcl.2009.07.125] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 11/21/2022]
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27
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McGowan E, Hoyt SB, Li X, Lyons KA, Abbadie C. A Peripherally Acting Nav1.7 Sodium Channel Blocker Reverses Hyperalgesia and Allodynia on Rat Models of Inflammatory and Neuropathic Pain. Anesth Analg 2009; 109:951-8. [DOI: 10.1213/ane.0b013e3181b01b02] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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28
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Discovery of isoxazole voltage gated sodium channel blockers for treatment of chronic pain. Bioorg Med Chem Lett 2009; 19:5334-8. [DOI: 10.1016/j.bmcl.2009.07.135] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2009] [Revised: 07/27/2009] [Accepted: 07/29/2009] [Indexed: 11/21/2022]
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29
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Dib-Hajj SD, Binshtok AM, Cummins TR, Jarvis MF, Samad T, Zimmermann K. Voltage-gated sodium channels in pain states: Role in pathophysiology and targets for treatment. ACTA ACUST UNITED AC 2009; 60:65-83. [DOI: 10.1016/j.brainresrev.2008.12.005] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2008] [Indexed: 12/19/2022]
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30
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Mathews KA. Neuropathic pain in dogs and cats: if only they could tell us if they hurt. Vet Clin North Am Small Anim Pract 2009; 38:1365-414, vii-viii. [PMID: 18954689 DOI: 10.1016/j.cvsm.2008.09.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Neuropathic pain is difficult to diagnose in veterinary patients because they are unable to verbalize their pain. By assuming that neuropathic pain may exist based on the history of events that each patient has experienced, a focused client history and neurologic examination may identify a lesion resulting in persistent or spontaneous pain. Once neuropathic pain is diagnosed, a trial analgesic or acupuncture session(s) should be prescribed with instructions for owners to observe behavior. Dosing of the analgesic can be titrated to the patient's needs while avoiding adverse effects. When a particular analgesic may be ineffectual, an alternate class should be tried. As research into the neurobiologic mechanisms of neuropathic pain continues, specific therapies for its management should eventually appear in the human clinical setting and subsequently be investigated for veterinary clinical use.
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Affiliation(s)
- Karol A Mathews
- Emergency and Critical Care Medicine, Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
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31
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Lanz S, Maihöfner C. Symptome und pathophysiologische Mechanismen neuropathischer Schmerzsyndrome. DER NERVENARZT 2009; 80:430-44. [DOI: 10.1007/s00115-008-2630-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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Tsuchihara T, Ogata S, Nemoto K, Okabayashi T, Nakanishi K, Kato N, Morishita R, Kaneda Y, Uenoyama M, Suzuki S, Amako M, Kawai T, Arino H. Nonviral retrograde gene transfer of human hepatocyte growth factor improves neuropathic pain-related phenomena in rats. Mol Ther 2009; 17:42-50. [PMID: 18941443 PMCID: PMC2834986 DOI: 10.1038/mt.2008.214] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 09/04/2008] [Indexed: 12/11/2022] Open
Abstract
Peripheral nerve injury occasionally causes chronic neuropathic pain with hyperalgesia and allodynia. However, its treatment is difficult. Here, we used a chronic constriction injury (CCI) model in rats to investigate the effects on experimental neuropathic pain of the human hepatocyte growth factor (HGF) gene delivered into the nervous system by retrograde axonal transport following its repeated intramuscular transfer, using liposomes containing the hemagglutinating virus of Japan (HVJ). CCI (control) rats exhibited marked mechanical allodynia and thermal hyperalgesia, and decreased blood flow in sciatic nerve and hind paw. All these changes were significantly reversed by HGF gene transfer. In the sciatic nerve in HGF-treated rats, the size-frequency distributions for myelinated and unmyelinated axons each showed a rightward shift, the number of myelinated axons >5 microm in diameter was significantly increased, and the mean diameter of unmyelinated axons was significantly increased (versus CCI rats). Levels of P2X3, P2X4, and P2Y1 receptor mRNAs, and of interleukin-6 (IL-6) and activating transcription factor 3 (ATF3) mRNAs, were elevated in the ipsilateral dorsal root ganglia and/or sciatic nerve by CCI, and these levels were decreased by HGF gene transfer. These results may point toward a potential new treatment strategy for chronic neuropathic pain in this model.
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Affiliation(s)
- Toyokazu Tsuchihara
- Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Japan
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33
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Docherty RJ, Farmer CE. The pharmacology of voltage-gated sodium channels in sensory neurones. Handb Exp Pharmacol 2009:519-61. [PMID: 19655117 DOI: 10.1007/978-3-540-79090-7_15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels (VGSCs) are vital for the normal functioning of most excitable cells. At least nine distinct functional subtypes of VGSCs are recognized, corresponding to nine genes for their pore-forming alpha-subunits. These have different developmental expression patterns, different tissue distributions in the adult and are differentially regulated at the cellular level by receptor-coupled cell signalling systems. Unsurprisingly, VGSC blockers are found to be useful as drugs in diverse clinical applications where excessive excitability of tissue leads to pathological dysfunction, e.g. epilepsy or cardiac tachyarrhythmias. The effects of most clinically useful VGSC blockers are use-dependent, i.e. their efficacy depends on channel activity. In addition, many natural toxins have been discovered that interact with VGSCs in complex ways and they have been used as experimental probes to study the structure and function of the channels and to better understand how drugs interact with the channels. Here we have attempted to summarize the properties of VGSCs in sensory neurones, discuss how they are regulated by cell signalling systems and we have considered briefly current concepts of their physiological function. We discuss in detail how drugs and toxins interact with archetypal VGSCs and where possible consider how they act on VGSCs in peripheral sensory neurones. Increasingly, drugs that block VGSCs are being used as systemic analgesic agents in chronic pain syndromes, but the full potential for VGSC blockers in this indication is yet to be realized and other applications in sensory dysfunction are also possible. Drugs targeting VGSC subtypes in sensory neurones are likely to provide novel systemic analgesics that are tissue-specific and perhaps even disease-specific, providing much-needed novel therapeutic approaches for the relief of chronic pain.
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Affiliation(s)
- Reginald J Docherty
- Neurorestoration Group, Wolfson CARD, King's College London, London SE1 9RT, UK.
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34
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Frank B, Cousins MJ. Pregabalin in the treatment of neuropathic pain associated with diabetic peripheral neuropathy. FUTURE NEUROLOGY 2008. [DOI: 10.2217/14796708.3.6.631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neuropathic pain associated with diabetic peripheral neuropathy (DPN) is a common debilitating complication of diabetes mellitus with unmet therapeutic needs. Pregabalin is a recently introduced α2-δ subunit ligand at the voltage- sensitive calcium channel that has shown good efficacy with a tolerable side-effect profile in the treatment of PDN. According to the Australian datasheet, 1438 patients have been studied receiving either placebo (460) or pregabalin (978). The dose ranged from 75 to 600 mg daily. The number needed to treat averaged from the published data is 3.8 patients for the two higher doses. Pregabalin has a linearly increased plasma concentration with dose escalation and achieves analgesia as early as 1 day after initiating therapy. As its mechanism of action is different from other anticonvulsants and antidepressants, and interactions with other drugs are unlikely from the pharmacokinetic profile, combining pregabalin with other agents that are effective in DPN is a clinically safe option and should result in improved pain control.
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Affiliation(s)
- B Frank
- Pain Medicine & Research Institute, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
| | - MJ Cousins
- Pain Medicine & Research Institute, Royal North Shore Hospital, St Leonards, Sydney, NSW, 2065, Australia
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35
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Governing role of primary afferent drive in increased excitation of spinal nociceptive neurons in a model of sciatic neuropathy. Exp Neurol 2008; 214:219-28. [PMID: 18773893 DOI: 10.1016/j.expneurol.2008.08.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 07/31/2008] [Accepted: 08/10/2008] [Indexed: 01/07/2023]
Abstract
Previously we reported that the cuff model of peripheral neuropathy, in which a 2 mm polyethylene tube is implanted around the sciatic nerve, exhibits aspects of neuropathic pain behavior in rats similar to those in humans and causes robust hyperexcitation of spinal nociceptive dorsal horn neurons. The mechanisms mediating this increased excitation are not known and remain a key unresolved question in models of peripheral neuropathy. In anesthetized adult male Sprague-Dawley rats 2-6 weeks after cuff implantation we found that elevated discharge rate of single lumbar (L(3-4)) wide dynamic range (WDR) neurons persists despite acute spinal transection (T9) but is reversed by local conduction block of the cuff-implanted sciatic nerve; lidocaine applied distal to the cuff (i.e. between the cuff and the cutaneous receptive field) decreased spontaneous baseline discharge of WDR dorsal horn neurons approximately 40% (n=18) and when applied subsequently proximal to the cuff, i.e. between the cuff and the spinal cord, it further reduced spontaneous discharge by approximately 60% (n=19; P<0.05 proximal vs. distal) to a level that was not significantly different from that of naive rats. Furthermore, in cuff-implanted rats WDR neurons (n=5) responded to mechanical cutaneous stimulation with an exaggerated afterdischarge which was reversed entirely by proximal nerve conduction block. These results demonstrate that the hyperexcited state of spinal dorsal horn neurons observed in this model of peripheral neuropathy is not maintained by tonic descending facilitatory mechanisms. Rather, on-going afferent discharges originating from the sciatic nerve distal to, at, and proximal to the cuff maintain the synaptically-mediated gain in discharge of spinal dorsal horn WDR neurons and hyperresponsiveness of these neurons to cutaneous stimulation. Our findings reveal that ectopic afferent activity from multiple regions along peripheral nerves may drive CNS changes and the symptoms of pain associated with peripheral neuropathy.
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36
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Pharmacological characterization and gene expression profiling of an L5/L6 spinal nerve ligation model for neuropathic pain in mice. Neuroscience 2008; 153:492-500. [DOI: 10.1016/j.neuroscience.2008.02.031] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 02/15/2008] [Accepted: 02/19/2008] [Indexed: 11/22/2022]
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37
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Kaczorowski GJ, McManus OB, Priest BT, Garcia ML. Ion channels as drug targets: the next GPCRs. ACTA ACUST UNITED AC 2008; 131:399-405. [PMID: 18411331 PMCID: PMC2346569 DOI: 10.1085/jgp.200709946] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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38
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McGaraughty S, Chu KL, Scanio MJC, Kort ME, Faltynek CR, Jarvis MF. A selective Nav1.8 sodium channel blocker, A-803467 [5-(4-chlorophenyl-N-(3,5-dimethoxyphenyl)furan-2-carboxamide], attenuates spinal neuronal activity in neuropathic rats. J Pharmacol Exp Ther 2007; 324:1204-11. [PMID: 18089840 DOI: 10.1124/jpet.107.134148] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We have recently reported that systemic delivery of A-803467 [5-(4-chlorophenyl-N-(3,5-dimethoxyphenyl)furan-2-carboxamide], a selective Na(v)1.8 sodium channel blocker, reduces behavioral measures of chronic pain. In the current study, the effects of A-803467 on evoked and spontaneous firing of wide dynamic range (WDR) neurons were measured in uninjured and rats with spinal nerve ligations (SNLs). Administration of A-803467 (10-30 mg/kg i.v.) reduced mechanically evoked (10-g von Frey hair) and spontaneous WDR neuronal activity in SNL rats. In uninjured rats, A-803467 (20 mg/kg i.v.) transiently reduced evoked but not spontaneous firing of WDR neurons. The systemic effects of A-803467 in SNL rats were not altered by spinal transection or by systemic pretreatment with the transient receptor potential vanilloid type 1 (TRPV1) receptor agonist, resiniferatoxin, at doses that impair the function of TRPV1-expressing fibers. To determine sites of action, A-803467 was administered into spinal tissue, into the uninjured L4 dorsal root ganglion (DRG), or into the neuronal receptive field. Injections of A-803467 into the L4 DRG (30-100 nmol/1 mul) or into the hindpaw receptive field (300 nmol/50 mul) reduced evoked but not spontaneous WDR firing. In contrast, intraspinal (50-150 nmol/0.5 mul) injection of A-803467 decreased both evoked and spontaneous discharges of WDR neurons. Thus, Na(v)1.8 sodium channels on the cell bodies/axons within the L4 DRG as well as on peripheral and central terminals of primary afferent neurons regulate the inflow of low-intensity mechanical signals to spinal WDR neurons. However, Na(v)1.8 sodium channels on central terminals seem to be key to the modulation of spontaneous firing in SNL rats.
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Affiliation(s)
- Steve McGaraughty
- Neuroscience Research, Abbott Laboratories, R4PM, AP9-1, 100 Abbott Park Rd., Abbott Park, IL 60064-6118, USA.
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Yogeeswari P, Ragavendran JV, Sriram D, Kavya R, Vanitha K, Neelakantan H. Newer N-Phthaloyl GABA Derivatives with Antiallodynic and Antihyperalgesic Activities in Both Sciatic Nerve and Spinal Nerve Ligation Models of Neuropathic Pain. Pharmacology 2007; 81:21-31. [PMID: 17785996 DOI: 10.1159/000107711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Accepted: 04/17/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND There is considerable research evidence supporting a palliative role for gamma-aminobutyric acid (GABA)-ergic neurotransmission and voltage-gated sodium channel blockade in neuropathic pain conditions. Hence, the present study was undertaken to assess the peripheral analgesic, antiallodynic and antihyperalgesic activities of the synthesized structural analogues of GABA. METHODS The screening study included acute tissue injury, chronic constriction injury (CCI), and spinal nerve ligation (SNL) models of neuropathic pain. RESULTS All of the tested compounds sup-pressed the acetic acid-induced writhing response significantly in comparison to the control. In particular, compound JVP-8 was observed to be the most active compound with percent inhibition greater than that of the standard drug aspirin (97.8% inhibition of writhing response as against 97.0% shown by aspirin). In neuropathic pain studies, compound JVP-5 (100 mg/kg i.p.) emerged as the most active compound affording maximum protection against dynamic allodynia and mechanical hyperalgesia in the CCI model, and against spontaneous pain and mechanical hyperalgesia in SNL rats. CONCLUSION In this study, we have demonstrated that combining phthalimide pharmacophore with GABA has evolved compounds effective for the treatment of neuropathic pain.
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Affiliation(s)
- Perumal Yogeeswari
- Pharmacy Group, Birla Institute of Technology and Science, Pilani, Rajasthan, India.
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Affiliation(s)
- Donald J Kyle
- Discovery Research, Purdue Pharma L.P., 6 Cedar Brook Drive, Cranbury, New Jersey 08512, USA.
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Jarvis MF, Honore P, Shieh CC, Chapman M, Joshi S, Zhang XF, Kort M, Carroll W, Marron B, Atkinson R, Thomas J, Liu D, Krambis M, Liu Y, McGaraughty S, Chu K, Roeloffs R, Zhong C, Mikusa JP, Hernandez G, Gauvin D, Wade C, Zhu C, Pai M, Scanio M, Shi L, Drizin I, Gregg R, Matulenko M, Hakeem A, Gross M, Johnson M, Marsh K, Wagoner PK, Sullivan JP, Faltynek CR, Krafte DS. A-803467, a potent and selective Nav1.8 sodium channel blocker, attenuates neuropathic and inflammatory pain in the rat. Proc Natl Acad Sci U S A 2007; 104:8520-5. [PMID: 17483457 PMCID: PMC1895982 DOI: 10.1073/pnas.0611364104] [Citation(s) in RCA: 389] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Activation of tetrodotoxin-resistant sodium channels contributes to action potential electrogenesis in neurons. Antisense oligonucleotide studies directed against Na(v)1.8 have shown that this channel contributes to experimental inflammatory and neuropathic pain. We report here the discovery of A-803467, a sodium channel blocker that potently blocks tetrodotoxin-resistant currents (IC(50) = 140 nM) and the generation of spontaneous and electrically evoked action potentials in vitro in rat dorsal root ganglion neurons. In recombinant cell lines, A-803467 potently blocked human Na(v)1.8 (IC(50) = 8 nM) and was >100-fold selective vs. human Na(v)1.2, Na(v)1.3, Na(v)1.5, and Na(v)1.7 (IC(50) values >or=1 microM). A-803467 (20 mg/kg, i.v.) blocked mechanically evoked firing of wide dynamic range neurons in the rat spinal dorsal horn. A-803467 also dose-dependently reduced mechanical allodynia in a variety of rat pain models including: spinal nerve ligation (ED(50) = 47 mg/kg, i.p.), sciatic nerve injury (ED(50) = 85 mg/kg, i.p.), capsaicin-induced secondary mechanical allodynia (ED(50) approximately 100 mg/kg, i.p.), and thermal hyperalgesia after intraplantar complete Freund's adjuvant injection (ED(50) = 41 mg/kg, i.p.). A-803467 was inactive against formalin-induced nociception and acute thermal and postoperative pain. These data demonstrate that acute and selective pharmacological blockade of Na(v)1.8 sodium channels in vivo produces significant antinociception in animal models of neuropathic and inflammatory pain.
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Affiliation(s)
- Michael F. Jarvis
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
- To whom correspondence may be addressed at:
Abbott Laboratories, R-4PM, AP9A/3,100 Abbott Park Road, Abbott Park, IL 60064. E-mail:
| | - Prisca Honore
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Char-Chang Shieh
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | - Shailen Joshi
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Xu-Feng Zhang
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Michael Kort
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - William Carroll
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | | | | | | | | | - Yi Liu
- Icagen, Inc., Durham, NC 27703
| | - Steve McGaraughty
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Katharine Chu
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | - Chengmin Zhong
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Joseph P. Mikusa
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | - Donna Gauvin
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Carrie Wade
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Chang Zhu
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Madhavi Pai
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Marc Scanio
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Lei Shi
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Irene Drizin
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Robert Gregg
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Mark Matulenko
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | - Ahmed Hakeem
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | | | - Kennan Marsh
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | - James P. Sullivan
- *Neuroscience Research, Abbott Laboratories, Abbott Park, IL 60064; and
| | | | - Douglas S. Krafte
- Icagen, Inc., Durham, NC 27703
- To whom correspondence may be addressed at:
Icagen, Inc., P.O. Box 14487, Research Triangle Park, NC 27709. E-mail:
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Abstract
In this article, we review the key basic mechanisms associated with this phenomena and more recently identified mechanisms that are current areas of interest. Although many of these pain mechanisms apply throughout the body, we attempt to describe these mechanisms in the context of trigeminal pain.
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Affiliation(s)
- Michael A Henry
- Department of Endodontics, University of Texas Health Science Center at San Antonio School of Dentistry, Mail Code 7892, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Yogeeswari P, Ragavendran JV, Sriram D. Neuropathic pain: strategies in drug discovery and treatment. Expert Opin Drug Discov 2007; 2:169-84. [DOI: 10.1517/17460441.2.2.169] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Neuropathic pain remains a large unmet medical need. A number of therapeutic options exist, but efficacy and tolerability are less than satisfactory. Based on animal models and limited data from human patients, the pain and hypersensitivity that characterize neuropathic pain are associated with spontaneous discharges of normally quiescent nociceptors. Sodium channel blockers inhibit this spontaneous activity, reverse nerve injury-induced pain behavior in animals and alleviate neuropathic pain in humans. Several sodium channel subtypes are expressed primarily in sensory neurons and may contribute to the efficacy of sodium channel blockers. In this report, the authors review the current understanding of the role of sodium channels and of specific sodium channel subtypes in neuropathic pain signaling.
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Affiliation(s)
- Birgit T Priest
- Merck Research Laboratories, Department of Ion Channels, Rahway, NJ 07065, USA.
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Abstract
PURPOSE OF REVIEW In this review, we summarize the new drugs in development in the anaesthesia field. RECENT FINDINGS There are some interesting approaches, including pro-drugs of propofol such as Aquavan (MGI Pharma, Bloomington, Minnesota, USA) and novel 'soft-drug' sedatives and hypnotics (e.g. CNS-7259X and TD-4756) as well as a novel approach to terminate the action of steroidal neuromuscular blockers (sugammadex). There is also significant activity in the field of novel analgesics. Particularly addressing the fields of sedatives, hypnotics and neuromuscular blockers, however, there is relatively little drug discovery activity currently. Part of the reason for this may be that the mechanisms of action of anaesthetics are not fully understood. This cannot be the whole story, however, since attractive new targets have recently been identified. For example, an agent with selective actions at the beta3-containing subunit of the gamma-amino butyric acid-A receptor is likely to have the hypnotic effects of propofol without the cardiac depressant side-effects. SUMMARY We consider the main reason for low activity is the perception in industry that there is little need for new drugs in anaesthesia because the needs are well addressed by existing agents. If this is not the case then anaesthesiologists need to be more effective in communicating their requirements.
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Ilyin VI, Pomonis JD, Whiteside GT, Harrison JE, Pearson MS, Mark L, Turchin PI, Gottshall S, Carter RB, Nguyen P, Hogenkamp DJ, Olanrewaju S, Benjamin E, Woodward RM. Pharmacology of 2-[4-(4-Chloro-2-fluorophenoxy)phenyl]-pyrimidine-4-carboxamide: A Potent, Broad-Spectrum State-Dependent Sodium Channel Blocker for Treating Pain States. J Pharmacol Exp Ther 2006; 318:1083-93. [PMID: 16728593 DOI: 10.1124/jpet.106.104737] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Voltage-gated Na(+) channels may play important roles in establishing pathological neuronal hyperexcitability associated with chronic pain in humans. Na(+) channel blockers, such as carbamazepine (CBZ) and lamotrigine (LTG), are efficacious in treating neuropathic pain; however, their therapeutic utility is compromised by central nervous system side effects. We reasoned that it may be possible to gain superior control over pain states and, in particular, a better therapeutic index, by designing broad-spectrum Na(+) channel blockers with higher potency, faster onset kinetics, and greater levels of state dependence than existing drugs. 2-[4-(4-Chloro-2-fluorophenoxy)phenyl]-pyrimidine-4-carboxamide (PPPA) is a novel structural analog of the state-dependent Na(+) channel blocker V102862 [4-(4-fluorophenoxy)benzaldehyde semicarbazone]. Tested on recombinant rat Na(v)1.2 channels and native Na(+) currents in cultured rat dorsal root ganglion neurons, PPPA was approximately 1000 times more potent, had 2000-fold faster binding kinetics, and > or =10-fold higher levels of state dependence than CBZ and LTG. Tested in rat pain models against mechanical endpoints, PPPA had minimal effective doses of 1 to 3 mg/kg p.o. in partial sciatic nerve ligation, Freund's complete adjuvant, and postincisional pain. In all cases, efficacy was similar to clinically relevant comparators. Importantly, PPPA did not produce motor deficits in the accelerating Rotarod assay of ataxia at doses up to 30 mg/kg p.o., indicating a therapeutic index >10, which was superior to CBZ and LTG. Our experiments suggest that high-potency, broad-spectrum, state-dependent Na(+) channel blockers will have clinical utility for treating neuropathic, inflammatory, and postsurgical pain. Optimizing the biophysical parameters of broad-spectrum voltage-gated Na(+) channel blockers may lead to improved pain therapeutics.
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Affiliation(s)
- Victor I Ilyin
- Discovery Research, Purdue Pharma LP, Cranbury, NJ 08512, USA.
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Novel Sodium Channel Blockers for the Treatment of Neuropathic Pain. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2006. [DOI: 10.1016/s0065-7743(06)41004-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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