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Zhou C, Tang L, Yin Q, Yang L, Gong D, Kang Y, Cao H, Fan J, Zhang Y, Qian D, Zhang Q, Ke B, Liu J, Zhang W, Yang J. Novel compound LL-a produces long and nociceptive-selective regional anesthesia via TRPV1 channels in rodents sciatic nerve block model. Reg Anesth Pain Med 2020; 45:412-418. [PMID: 32284350 DOI: 10.1136/rapm-2019-101057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/17/2020] [Accepted: 03/19/2020] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND OBJECTIVE Long-acting nociceptive-selective regional anesthesia has remained an elusive clinical goal. We aspired to identify a novel compound that would produce nociceptive-selective regional anesthesia through the transient receptor potential vanilloid 1 (TRPV1) channels. METHODS We designed and synthesized a novel compound (LL-a) that penetrates the cell membrane through TRPV1 channels and binds to voltage-gated sodium channels. The regional anesthetic effect of LL-a was evaluated in a rodent sciatic nerve block model. Electrophysiological recording was applied to test the inhibition of LL-a on voltage-gated sodium channel currents. RESULTS LL-a inhibited sodium channel currents on the dorsal root ganglion neurons of mice and this action was diminished by TRPV1 channel knockout. In a sciatic nerve block model of a rat, 0.2% and 0.4% (w/v) LL-a produced selective sensory block with median (IQR) durations of 42.0 (24.0, 48.0) and 72.0 (69.0, 78.0) hours, respectively. No motor block was found for 0.2% LL-a. 0.4% LL-a produced a motor block with a median (IQR) duration of 3.0 (0.0, 6.0) hours. This selective sensory block was not observed on TRPV1 knockout mice. As a positive control, 0.5% and 0.75% levobupivacaine produced a non-selective sciatic nerve block with median (IQR) durations of 2.8 (2.6, 2.8) and 3.8 (3.8, 4.8) hours, respectively. No systemic or local irritation was observed during injection of LL-a and sensory and motor function completely recovered for all the animals. CONCLUSIONS LL-a is a potential novel local anesthetic for long-lasting nociceptive-selective analgesia.
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Affiliation(s)
- Cheng Zhou
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Lei Tang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Qinqin Yin
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Linghui Yang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Deying Gong
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Yi Kang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Hangxue Cao
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Jing Fan
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Yujun Zhang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Duo Qian
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Qianqian Zhang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Bowen Ke
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Jin Liu
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China.,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Wensheng Zhang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China .,Department of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
| | - Jun Yang
- Laboratory of Anesthesia & Critical Care Medicine, Translational Neuroscience Center, National Clinical Research Center for Geriatrics, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
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2
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Abstract
Lidocaine, as the only local anesthetic approved for intravenous administration in the clinic, can relieve neuropathic pain, hyperalgesia, and complex regional pain syndrome. Intravenous injection of lidocaine during surgery is considered as an effective strategy to control postoperative pain, but the mechanism of its analgesic effect has not been fully elucidated. This paper intends to review recent studies on the mechanism of the analgesic effect of lidocaine. To the end, we conducted an electronic search of the PubMed database. The search period was from 5 years before June 2019. Lidocaine was used as the search term. A total of 659 documents were obtained, we included 17 articles. These articles combined with the 34 articles found by hand searching made up the 51 articles that were ultimately included. We reviewed the analgesic mechanism of lidocaine in the central nervous system.
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Affiliation(s)
- Xi Yang
- Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University
- Department of Anesthesiology, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital
| | - Xinchuan Wei
- Department of Anesthesiology, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital
| | - Yi Mu
- National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Qian Li
- Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University
| | - Jin Liu
- Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University
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3
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Hermanns H, Hollmann MW, Stevens MF, Lirk P, Brandenburger T, Piegeler T, Werdehausen R. Molecular mechanisms of action of systemic lidocaine in acute and chronic pain: a narrative review. Br J Anaesth 2019; 123:335-349. [DOI: 10.1016/j.bja.2019.06.014] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 02/07/2023] Open
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4
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Kodirov SA. Tale of tail current. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:78-97. [PMID: 31238048 DOI: 10.1016/j.pbiomolbio.2019.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023]
Abstract
The largest biomass of channel proteins is located in unicellular organisms and bacteria that have no organs. However, orchestrated bidirectional ionic currents across the cell membrane via the channels are important for the functioning of organs of organisms, and equally concern both fauna or flora. Several ion channels are activated in the course of action potentials. One of the hallmarks of voltage-dependent channels is a 'tail current' - deactivation as observed after prior and sufficient activation predominantly at more depolarized potentials e.g. for Kv while upon hyperpolarization for HCN α subunits. Tail current also reflects the timing of channel closure that is initiated upon termination of stimuli. Finally, deactivation of currents during repolarization could be a selective estimate for given channel as in case of HERG, if dedicated long and more depolarized 'tail pulse' is used. Since from a holding potential of e.g. -70 mV are often a family of outward K+ currents comprising IA and IK are simultaneously activated in native cells.
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Affiliation(s)
- Sodikdjon A Kodirov
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA; Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341, Russia; Institute of Experimental Medicine, I. P. Pavlov Department of Physiology, Russian Academy of Medical Sciences, Saint Petersburg, Russia; Laboratory of Emotions' Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
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5
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Chen SJ, Xu Y, Liang YM, Cao Y, Lv JY, Pang JX, Zhou PZ. Identification and characterization of a series of novel HCN channel inhibitors. Acta Pharmacol Sin 2019; 40:746-754. [PMID: 30315249 DOI: 10.1038/s41401-018-0162-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 08/13/2018] [Indexed: 11/09/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play a critical role in controlling pacemaker activity in both heart and nervous system. Developing HCN channel inhibitors has been proposed to be an important strategy for the treatment of pain, heart failure, arrhythmias, and epilepsy. One HCN channel inhibitor, ivabradine, has been clinically approved for the treatment of angina pectoris and heart failure. In this study, we designed and synthesized eight alkanol amine derivatives, and assessed their effects on HCN channels expressed in COS7 cells using a whole-cell patch clamp method. Among them, compound 4e displayed the most potent inhibitory activity with an IC50 of 2.9 ± 1.2 µM at - 120 mV on HCN2 channel expressed in COS7 cells. Further analysis revealed that application of compound 4e (10 μM) caused a slowing of activation and a hyperpolarizing shift (ΔV1/2 = - 30.2 ± 2.9 mV, n = 5) in the voltage dependence of HCN2 channel activation. The inhibitory effect of compound 4e on HCN1 and HCN4 channel expressed in COS7 cells was less potent with IC50 of 17.2 ± 1.3 and 7.3 ± 1.2 μM, respectively. Besides, we showed that application of compound 4e (10 μM) inhibited Ih and action potential firing in acutely dissociated mouse small dorsal root ganglion neurons. Our study provides a new strategy for the design and development of potent HCN channel inhibitors.
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6
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Tanguay J, Callahan KM, D'Avanzo N. Characterization of drug binding within the HCN1 channel pore. Sci Rep 2019; 9:465. [PMID: 30679654 PMCID: PMC6345760 DOI: 10.1038/s41598-018-37116-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 11/29/2018] [Indexed: 11/09/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate rhythmic electrical activity of cardiac pacemaker cells, and in neurons play important roles in setting resting membrane potentials, dendritic integration, neuronal pacemaking, and establishing action potential threshold. Block of HCN channels slows the heart rate and is currently used to treat angina. However, HCN block also provides a promising approach to the treatment of neuronal disorders including epilepsy and neuropathic pain. While several molecules that block HCN channels have been identified, including clonidine and its derivative alinidine, lidocaine, mepivacaine, bupivacaine, ZD7288, ivabradine, zatebradine, and cilobradine, their low affinity and lack of specificity prevents wide-spread use. Different studies suggest that the binding sites of these inhibitors are located in the inner vestibule of HCN channels, but the molecular details of their binding remain unknown. We used computational docking experiments to assess the binding sites and mode of binding of these inhibitors against the recently solved atomic structure of human HCN1 channels, and a homology model of the open pore derived from a closely related CNG channel. We identify a possible hydrophobic groove in the pore cavity that plays an important role in conformationally restricting the location and orientation of drugs bound to the inner vestibule. Our results also help explain the molecular basis of the low-affinity binding of these inhibitors, paving the way for the development of higher affinity molecules.
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Affiliation(s)
- Jérémie Tanguay
- Department of Physics, Université de Montréal, Montréal, Canada
| | - Karen M Callahan
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Canada
| | - Nazzareno D'Avanzo
- Department of Pharmacology and Physiology, Université de Montréal, Montréal, Canada.
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7
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Sartiani L, Mannaioni G, Masi A, Novella Romanelli M, Cerbai E. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels. Pharmacol Rev 2017; 69:354-395. [PMID: 28878030 DOI: 10.1124/pr.117.014035] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.
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Affiliation(s)
- Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Alessio Masi
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
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8
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Putrenko I, Yip R, Schwarz SKW, Accili EA. Cation and voltage dependence of lidocaine inhibition of the hyperpolarization-activated cyclic nucleotide-gated HCN1 channel. Sci Rep 2017; 7:1281. [PMID: 28455536 PMCID: PMC5430837 DOI: 10.1038/s41598-017-01253-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 03/28/2017] [Indexed: 12/17/2022] Open
Abstract
Lidocaine is known to inhibit the hyperpolarization-activated mixed cation current (Ih) in cardiac myocytes and neurons, as well in cells transfected with cloned Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels. However, the molecular mechanism of Ih inhibition by this drug has been limitedly explored. Here, we show that inhibition of Ih by lidocaine, recorded from Chinese hamster ovary (CHO) cells expressing the HCN1 channel, reached a steady state within one minute and was reversible. Lidocaine inhibition of Ih was greater at less negative voltages and smaller current amplitudes whereas the voltage-dependence of Ih activation was unchanged. Lidocaine inhibition of Ih measured at −130 mV (a voltage at which Ih is fully activated) was reduced, and Ih amplitude was increased, when the concentration of extracellular potassium was raised to 60 mM from 5.4 mM. By contrast, neither Ih inhibition by the drug nor Ih amplitude at +30 mV (following a test voltage-pulse to −130 mV) were affected by this rise in extracellular potassium. Together, these data indicate that lidocaine inhibition of Ih involves a mechanism which is antagonized by hyperpolarizing voltages and current flow.
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Affiliation(s)
- Igor Putrenko
- Department of Cellular and Physiological Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.,Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Raymond Yip
- Department of Cellular and Physiological Sciences, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephan K W Schwarz
- Department of Anesthesiology, Pharmacology & Therapeutics, The University of British Columbia, Vancouver, British Columbia, Canada.,Department of Anesthesia, St. Paul's Hospital/Providence Health Care, Vancouver, British Columbia, Canada
| | - Eric A Accili
- Department of Cellular and Physiological Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
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9
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Helås T, Sagafos D, Kleggetveit I, Quiding H, Jönsson B, Segerdahl M, Zhang Z, Salter H, Schmelz M, Jørum E. Pain thresholds,supra-threshold pain and lidocaine sensitivity in patients with erythromelalgia, including the I848Tmutation in NaV1.7. Eur J Pain 2017; 21:1316-1325. [DOI: 10.1002/ejp.1030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2017] [Indexed: 11/09/2022]
Affiliation(s)
- T. Helås
- Section of Clinical Neurophysiology, Department of Neurology; Oslo University Hospital - Rikshospitalet; Norway
| | - D. Sagafos
- Section of Clinical Neurophysiology, Department of Neurology; Oslo University Hospital - Rikshospitalet; Norway
| | - I.P. Kleggetveit
- Section of Clinical Neurophysiology, Department of Neurology; Oslo University Hospital - Rikshospitalet; Norway
| | | | | | | | - Z. Zhang
- Astra-Zeneca R&D; Södertälje Sweden
| | - H. Salter
- Astra-Zeneca R&D; Södertälje Sweden
- Department of Clinical Neuroscience; Karolinska Institutet; Solna Sweden
| | - M. Schmelz
- Department of Anesthesiology Mannheim; Heidelberg University; Germany
| | - E. Jørum
- Section of Clinical Neurophysiology, Department of Neurology; Oslo University Hospital - Rikshospitalet; Norway
- Faculty of Medicine, Institute of Clinical Medicine; University of Oslo; Norway
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10
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Kodirov SA. Addictive neurons. THERAPEUTIC TARGETS FOR NEUROLOGICAL DISEASES 2017; 4:e1498. [PMID: 28649663 PMCID: PMC5479441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Since the reward center is considered to be the area tegmentalis ventralis of the hypothalamus, logically its neurons could mainly be responsible for addiction. However, the literature asserts that almost any neurons of CNS can respond to one or another addictive compound. Obviously not only addictive nicotine, but also alcohol, amphetamine, cannabis, cocaine, heroin and morphine may influence dopaminergic cells alone in VTA. Moreover, paradoxically some of these drugs ameliorate symptoms, counterbalance syndromes, cure diseases and improve health, not only those related to the CNS and in adults, but also almost all other organs and in children, e.g. epilepsy.
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Affiliation(s)
- Sodikdjon A. Kodirov
- I. P. Pavlov Department of Physiology, State Research Institute of Experimental Medicine, Russian Academy of Medical Sciences, Saint Petersburg 197376, Russia
- University of Texas at Brownsville, Department of Biological Sciences, Texas 78520, USA
- Johannes Gutenberg University, 55099 Mainz, Germany
- Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg 197341, Russia
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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11
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Central Nervous System-Toxic Lidocaine Concentrations Unmask L-Type Ca²⁺ Current-Mediated Action Potentials in Rat Thalamocortical Neurons: An In Vitro Mechanism of Action Study. Anesth Analg 2016; 122:1360-9. [PMID: 26771269 DOI: 10.1213/ane.0000000000001158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND High systemic lidocaine concentrations exert well-known toxic effects on the central nervous system (CNS), including seizures, coma, and death. The underlying mechanisms are still largely obscure, and the actions of lidocaine on supraspinal neurons have received comparatively little study. We recently found that lidocaine at clinically neurotoxic concentrations increases excitability mediated by Na-independent, high-threshold (HT) action potential spikes in rat thalamocortical neurons. Our goal in this study was to characterize these spikes and test the hypothesis that they are generated by HT Ca currents, previously implicated in neurotoxicity. We also sought to identify and isolate the specific underlying subtype of Ca current. METHODS We investigated the actions of lidocaine in the CNS-toxic concentration range (100 μM-1 mM) on ventrobasal thalamocortical neurons in rat brain slices in vitro, using whole-cell patch-clamp recordings aided by differential interference contrast infrared videomicroscopy. Drugs were bath applied; action potentials were generated using current clamp protocols, and underlying currents were identified and isolated with ion channel blockers and electrolyte substitution. RESULTS Lidocaine (100 μM-1 mM) abolished Na-dependent tonic firing in all neurons tested (n = 46). However, in 39 of 46 (85%) neurons, lidocaine unmasked evoked HT action potentials with lower amplitudes and rates of de-/repolarization compared with control. These HT action potentials remained during the application of tetrodotoxin (600 nM), were blocked by Cd (50 μM), and disappeared after superfusion with an extracellular solution deprived of Ca. These features implied that the unmasked potentials were generated by high-voltage-activated Ca channels and not by Na channels. Application of the L-type Ca channel blocker, nifedipine (5 μM), completely blocked the HT potentials, whereas the N-type Ca channel blocker, ω-conotoxin GVIA (1 μM), had little effect. CONCLUSIONS At clinically CNS-toxic concentrations, lidocaine unmasked in thalamocortical neurons evoked HT action potentials mediated by the L-type Ca current while substantially suppressing Na-dependent excitability. On the basis of the known role of an increase in intracellular Ca in the pathogenesis of local anesthetic neurotoxicity, this novel action represents a plausible contributing candidate mechanism for lidocaine's CNS toxicity in vivo.
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12
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Hu T, Liu N, Lv M, Ma L, Peng H, Peng S, Liu T. Lidocaine Inhibits HCN Currents in Rat Spinal Substantia Gelatinosa Neurons. Anesth Analg 2016; 122:1048-59. [PMID: 26756913 PMCID: PMC4791316 DOI: 10.1213/ane.0000000000001140] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Lidocaine, which blocks voltage-gated sodium channels, is widely used in surgical anesthesia and pain management. Recently, it has been proposed that the hyperpolarization-activated cyclic nucleotide (HCN) channel is one of the other novel targets of lidocaine. Substantia gelatinosa in the spinal dorsal horn, which plays key roles in modulating nociceptive information from primary afferents, comprises heterogeneous interneurons that can be electrophysiologically categorized by firing pattern. Our previous study demonstrated that a substantial proportion of substantia gelatinosa neurons reveal the presence of HCN current (Ih); however, the roles of lidocaine and HCN channel expression in different types of substantia gelatinosa neurons remain unclear. METHODS By using the whole-cell patch-clamp technique, we investigated the effect of lidocaine on Ih in rat substantia gelatinosa neurons of acute dissociated spinal cord slices. RESULTS We found that lidocaine rapidly decreased the peak Ih amplitude with an IC50 of 80 μM. The inhibition rate on Ih was not significantly different with a second application of lidocaine in the same neuron. Tetrodotoxin, a sodium channel blocker, did not affect lidocaine's effect on Ih. In addition, lidocaine shifted the half-activation potential of Ih from -109.7 to -114.9 mV and slowed activation. Moreover, the reversal potential of Ih was shifted by -7.5 mV by lidocaine. In the current clamp, lidocaine decreased the resting membrane potential, increased membrane resistance, delayed rebound depolarization latency, and reduced the rebound spike frequency. We further found that approximately 58% of substantia gelatinosa neurons examined expressed Ih, in which most of them were tonically firing. CONCLUSIONS Our studies demonstrate that lidocaine strongly inhibits Ih in a reversible and concentration-dependent manner in substantia gelatinosa neurons, independent of tetrodotoxin-sensitive sodium channels. Thus, our study provides new insight into the mechanism underlying the central analgesic effect of the systemic administration of lidocaine.
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Affiliation(s)
- Tao Hu
- From the Departments of *Pediatrics and †Anesthesiology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China; and ‡Center for Laboratory Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China
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13
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Nakahira K, Oshita K, Itoh M, Takano M, Sakaguchi Y, Ishihara K. Clinical Concentrations of Local Anesthetics Bupivacaine and Lidocaine Differentially Inhibit Human Kir2.x Inward Rectifier K+ Channels. Anesth Analg 2016; 122:1038-47. [PMID: 26756912 DOI: 10.1213/ane.0000000000001137] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Inward rectifier K channels of the Kir2.x subfamily are widely expressed in neuronal tissues, controlling neuronal excitability. Previous studies reported that local anesthetics (LAs) do not affect Kir2 channels. However, the effects have not been studied at large concentrations used in regional anesthesia. METHODS This study used the patch-clamp technique to examine the effects of bupivacaine and lidocaine on Kir2.1, Kir2.2, and Kir2.3 channels expressed in human embryonic kidney 293 cells. RESULTS When applied extracellularly in whole-cell recordings, both LAs inhibited Kir2.x currents in a voltage-independent manner. Inhibition with bupivacaine was slow and irreversible, whereas that with lidocaine was fast and reversible. Kir2.3 displayed a greater sensitivity to bupivacaine than Kir2.1 and Kir2.2 (50% inhibitory concentrations at approximately 5 minutes, 0.6 vs 8-10 mM), whereas their sensitivities to lidocaine were similar (50% inhibitory concentrations, 1.5-2.7 mM). Increases in the charged/neutral ratio of the LAs at an acidic extracellular pH attenuated their inhibitory effects, and a permanently charged lidocaine derivative QX-314 exhibited no effects when applied extracellularly. Inside-out experiments demonstrated that inhibition of Kir2.1 with cytoplasmic lidocaine and QX-314 was rapid and reversible, whereas that induced by bupivacaine was slow and irreversible. Furthermore, dose-inhibition relations for the charged form of bupivacaine and lidocaine obtained at different cytoplasmic pHs could be approximated by a single relation for each LA. CONCLUSIONS The results indicate that both LAs at clinical concentrations equilibrated rapidly with the intracellular milieu, differentially inhibiting Kir2.x channel function from the cytoplasmic side.
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Affiliation(s)
- Kei Nakahira
- From the *Department of Anesthesiology and Critical Care Medicine, Faculty of Medicine, Saga University, Saga, Japan; and †Department of Physiology, Kurume University School of Medicine, Kurume, Fukuoka, Japan
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14
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Novella Romanelli M, Sartiani L, Masi A, Mannaioni G, Manetti D, Mugelli A, Cerbai E. HCN Channels Modulators: The Need for Selectivity. Curr Top Med Chem 2016; 16:1764-91. [PMID: 26975509 PMCID: PMC5374843 DOI: 10.2174/1568026616999160315130832] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.
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Affiliation(s)
- Maria Novella Romanelli
- University of Florence, Department of Neurosciences, Psychology, Drug Research and Child's Health, Section of Pharmaceutical and Nutraceutical Sciences, via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
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15
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Hyperpolarization-activated cyclic nucleotide-gated channels may contribute to regional anesthetic effects of lidocaine. Anesthesiology 2015; 122:606-18. [PMID: 25485469 DOI: 10.1097/aln.0000000000000557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Local anesthetics (e.g., lidocaine) have been found to inhibit hyperpolarization-activated cyclic nucleotide-gated (HCN) channels besides sodium channels. However, the exact role of HCN channels in regional anesthesia in vivo is still elusive. METHODS Sciatic nerve block and intrathecal anesthesia were performed using lidocaine in wild-type and HCN1 channel knockout (HCN1) mice. EC50 of lidocaine and durations of 1% lidocaine were determined. In electrophysiologic recordings, effects of lidocaine on HCN channel currents, voltage-gated sodium channel currents, and neural membrane properties were recorded on dorsal root ganglia neurons. RESULTS In both sciatic nerve block and intrathecal anesthesia, EC50 of lidocaine for tactile sensory blockade (2 g von Frey fiber) was significantly increased in HCN1 mice, whereas EC50 of lidocaine for pinprick blockade was unaffected. Durations of 1% lidocaine were significantly shorter in HCN1 mice for both sciatic nerve block and intrathecal anesthesia (n = 10). ZD7288 (HCN blocker) could significantly prolong durations of 1% lidocaine including pinprick blockade in sciatic nerve block (n = 10). Forskolin (raising cyclic adenosine monophosphate to enhance HCN2) could significantly shorten duration of pinprick blockade of 1% lidocaine in sciatic nerve block (n = 10). In electrophysiologic recordings, lidocaine could nonselectively inhibit HCN channel and sodium channel currents both in large and in small dorsal root ganglia neurons (n = 5 to 6). Meanwhile, lidocaine caused neural membrane hyperpolarization and increased input resistance of dorsal root ganglia neurons but not in large dorsal root ganglia neurons from HCN1 mice (n = 5-7). CONCLUSIONS These data indicate that HCN channels may contribute to regional anesthetic effects of lidocaine. By inhibiting HCN channels, lidocaine could alter membrane properties of neurons.
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16
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Hofmann ME, Largent-Milnes TM, Fawley JA, Andresen MC. External QX-314 inhibits evoked cranial primary afferent synaptic transmission independent of TRPV1. J Neurophysiol 2014; 112:2697-706. [PMID: 25185814 DOI: 10.1152/jn.00316.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The cell-impermeant lidocaine derivative QX-314 blocks sodium channels via intracellular mechanisms. In somatosensory nociceptive neurons, open transient receptor potential vanilloid type 1 (TRPV1) receptors provide a transmembrane passageway for QX-314 to produce long-lasting analgesia. Many cranial primary afferents express TRPV1 at synapses on neurons in the nucleus of the solitary tract and caudal trigeminal nucleus (Vc). Here, we investigated whether QX-314 interrupts neurotransmission from primary afferents in rat brain-stem slices. Shocks to the solitary tract (ST) activated highly synchronous evoked excitatory postsynaptic currents (ST-EPSCs). Application of 300 μM QX-314 increased the ST-EPSC latency from TRPV1+ ST afferents, but, surprisingly, it had similar actions at TRPV1- ST afferents. Continued exposure to QX-314 blocked evoked ST-EPSCs at both afferent types. Neither the time to onset of latency changes nor the time to ST-EPSC failure differed between responses for TRPV1+ and TRPV1- inputs. Likewise, the TRPV1 antagonist capsazepine failed to prevent the actions of QX-314. Whereas QX-314 blocked ST-evoked release, the frequency and amplitude of spontaneous EPSCs remained unaltered. In neurons exposed to QX-314, intracellular current injection evoked action potentials suggesting a presynaptic site of action. QX-314 acted similarly at Vc neurons to increase latency and block EPSCs evoked from trigeminal tract afferents. Our results demonstrate that QX-314 blocked nerve conduction in cranial primary afferents without interrupting the glutamate release mechanism or generation of postsynaptic action potentials. The TRPV1 independence suggests that QX-314 either acted extracellularly or more likely entered these axons through an undetermined pathway common to all cranial primary afferents.
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Affiliation(s)
- Mackenzie E Hofmann
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon
| | - Tally M Largent-Milnes
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon
| | - Jessica A Fawley
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon
| | - Michael C Andresen
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon
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17
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Young GT, Emery EC, Mooney ER, Tsantoulas C, McNaughton PA. Inflammatory and neuropathic pain are rapidly suppressed by peripheral block of hyperpolarisation-activated cyclic nucleotide-gated ion channels. Pain 2014; 155:1708-1719. [PMID: 24861581 DOI: 10.1016/j.pain.2014.05.021] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 04/30/2014] [Accepted: 05/19/2014] [Indexed: 01/06/2023]
Abstract
Previous studies have shown that hyperpolarisation-activated cyclic nucleotide-gated (HCN)-2 ion channels regulate the firing frequency of nociceptive sensory neurons and thus play a central role in both inflammatory and neuropathic pain conditions. Here we use ivabradine, a clinically approved anti-anginal agent that blocks all HCN channel isoforms approximately equally, to investigate the effect on inflammatory and neuropathic pain of HCN ion channel block. We show that ivabradine does not have major off-target effects on a sample group of Na, Ca, and K ion channels, and that it is peripherally restricted because it is a substrate for the P-glycoprotein (PgP) multidrug transporter that is expressed in the blood-brain barrier. Its effects are therefore likely to be due to an action on HCN ion channels in peripheral sensory neurons. Using patch clamp electrophysiology, we found that ivabradine was a use-dependent blocker of native HCN channels expressed in small sensory neurons. Ivabradine suppressed the action potential firing that is induced in nociceptive neurons by elevation of intracellular cAMP. In the formalin model of inflammatory pain, ivabradine reduced pain behaviour only in the second (inflammatory) phase. In nerve injury and chemotherapy models of neuropathic pain, we observed rapid and effective analgesia as effective as that with gabapentin. We conclude that both inflammatory and neuropathic pain are rapidly inhibited by blocking HCN-dependent repetitive firing in peripheral nociceptive neurons.
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Affiliation(s)
- Gareth T Young
- Department of Pharmacology, University of Cambridge, Cambridge, UK Wolfson Centre for Age-Related Research, King's College London, Guy's Campus, London Bridge, London, UK
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18
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Intrathecal gabapentin does not act as a hyperpolarization-activated cyclic nucleotide-gated channel activator in the rat formalin test. Eur J Anaesthesiol 2009; 26:821-4. [DOI: 10.1097/eja.0b013e32832a991a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Olschewski A, Schnoebel-Ehehalt R, Li Y, Tang B, Bräu ME, Wolff M. Mexiletine and Lidocaine Suppress the Excitability of Dorsal Horn Neurons. Anesth Analg 2009; 109:258-64. [DOI: 10.1213/ane.0b013e3181a3d5d8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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20
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Devaud JM, Blunk A, Podufall J, Giurfa M, Grünewald B. Using local anaesthetics to block neuronal activity and map specific learning tasks to the mushroom bodies of an insect brain. Eur J Neurosci 2008; 26:3193-206. [PMID: 18028113 DOI: 10.1111/j.1460-9568.2007.05904.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The formation of a stable olfactory memory requires activity within several brain regions. The honeybee provides a valuable model to map complex olfactory learning tasks onto certain brain areas. To this end, we used injections of the local anaesthetic procaine to reversibly block spike activity in a specific brain region, the mushroom body (MB). We first investigated the physiological effects of procaine on cultured MB neurons from adult honeybee brains. Using the whole-cell configuration of the patch-clamp technique, we show that procaine blocks voltage-gated Na+ and K+ currents in a dose-dependent manner between 0.1 and 10 mm. The effects are reversible within a few minutes of wash. Lidocaine acts similarly, but is less effective at the tested concentrations. We then studied the role of the MBs during reversal learning by blocking the neural activity within these structures by injecting procaine. During reversal learning bees learn to revert their responses to two odorants, one rewarded (A+) and one unrewarded (B-), if their contingencies are changed (A- vs B+). Injecting procaine into the MBs impaired reversal learning. Procaine treatment during acquisition left the later retention of the initial learning (A+ vs B-) intact. Similarly, a differential conditioning task involving novel odorants (C+ vs D-) was intact under procaine treatment. Our experiments show that local injections of procaine can be used to map learning tasks onto specific regions of the insect brain. We conclude that intact MB activity is required for the acquisition of reversal learning, but not for simple differential learning tasks.
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21
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Abstract
Hyperpolarization-activated cation nonselective cyclic nucleotide-gated (HCN) channels mediate pacemaker currents that control basic rhythmic processes including heartbeat. Alterations in HCN channel expression or function have been described in both epilepsy and cardiac arrhythmias. Recent evidence suggests that pacemaker currents may also play an important role in ectopic neuronal activity that manifests as neuropathic pain. Pacemaker currents are subject to endogenous regulation by cyclic nucleotides, pH and perhaps phosphorylation. In addition, a number of neuromodulators with known roles in pain affect current density and kinetics. The pharmacology of a number of drugs that are commonly used to treat neuropathic pain includes effects on pacemaker currents. Altered pacemaker currents in injured tissues may be an important mechanism underlying neuropathic pain, and drugs that modulate these currents may offer new therapeutic options.
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Affiliation(s)
- Sean M Brown
- Johnson & Johnson Pharmaceutical Research & Development, L.L.C., San Diego, California, USA. schaplan@
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22
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Heurich M, Mousa SA, Lenzner M, Morciniec P, Kopf A, Welte M, Stein C. Influence of pain treatment by epidural fentanyl and bupivacaine on homing of opioid-containing leukocytes to surgical wounds. Brain Behav Immun 2007; 21:544-52. [PMID: 17174527 DOI: 10.1016/j.bbi.2006.10.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 10/17/2006] [Accepted: 10/19/2006] [Indexed: 11/22/2022] Open
Abstract
Endogenous opioids released from leukocytes extravasating into injured tissue can interact with peripheral opioid receptors to inhibit nociception. Animal studies have shown that the homing of opioid-producing leukocytes to the injured site is modulated by spinal blockade of noxious input. This study investigated whether epidural analgesia (EDA) influences the migration of beta-endorphin (END) and/or met-enkephalin (ENK)-containing leukocytes into the subcutaneous wound tissue of patients undergoing abdominal surgery. In part I patients received general anesthesia combined either with intra- and postoperative EDA (with bupivacaine and fentanyl) or with postoperative patient controlled intravenous analgesia (PCIA; with the opioid piritramide). In part II patients received general anesthesia combined with either epidural fentanyl or bupivacaine which was continued postoperatively. Samples of cutanous and subcutanous tissue were taken from the wound site at the beginning, at the end and at various times after surgery, and were examined by immunohistochemistry for the presence of END and ENK. We found that (i) epidural bupivacaine, fentanyl and PCIA provided similar and clinically acceptable postoperative pain relief; (ii) compared to PCIA, epidural bupivacaine or fentanyl did not change the gross inflammatory reaction within the surgical wound; (iii) opioid-containing leukocytes were almost absent in normal subcutaneous tissue but migrated to the inflamed wound tissue in ascending numbers within a few hours, reaching a peak at about 24 h after surgery; (iv) compared to PCIA, EDA resulted in significantly decreased homing of END-containing leukocytes to the injured site at 24 h after surgery; and (v) the magnitude of this decrease was similar regardless of the epidural medication. These findings suggest that nociceptive but not sympathetic neurons are primarily involved in the attraction of opioid-containing leukocytes during early stages of inflammation.
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MESH Headings
- Adjuvants, Anesthesia/immunology
- Adjuvants, Anesthesia/pharmacology
- Aged
- Analgesia, Patient-Controlled
- Analgesics, Opioid/immunology
- Analgesics, Opioid/therapeutic use
- Anesthesia, Epidural
- Anesthetics, Local/immunology
- Anesthetics, Local/therapeutic use
- Bupivacaine/immunology
- Bupivacaine/therapeutic use
- Cell Movement/drug effects
- Cell Movement/immunology
- Enkephalin, Methionine/drug effects
- Enkephalin, Methionine/immunology
- Enkephalin, Methionine/metabolism
- Female
- Fentanyl/immunology
- Fentanyl/therapeutic use
- Humans
- Leukocytes/drug effects
- Leukocytes/immunology
- Leukocytes/metabolism
- Longitudinal Studies
- Male
- Middle Aged
- Nociceptors/drug effects
- Nociceptors/immunology
- Pain, Postoperative/immunology
- Pain, Postoperative/prevention & control
- Pirinitramide/therapeutic use
- Subcutaneous Tissue/immunology
- Sympathetic Fibers, Postganglionic/drug effects
- Sympathetic Fibers, Postganglionic/immunology
- Wound Healing/drug effects
- Wound Healing/immunology
- beta-Endorphin/drug effects
- beta-Endorphin/immunology
- beta-Endorphin/metabolism
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Affiliation(s)
- Martin Heurich
- Klinik für Anaesthesiologie und operative Intensivmedizin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, D-12200 Berlin, Germany.
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23
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Abstract
Local anesthetics are used broadly to prevent or reverse acute pain and treat symptoms of chronic pain. This chapter, on the analgesic aspects of local anesthetics, reviews their broad actions that affect many different molecular targets and disrupt their functions in pain processing. Application of local anesthetics to peripheral nerve primarily results in the blockade of propagating action potentials, through their inhibition of voltage-gated sodium channels. Such inhibition results from drug binding at a site in the channel's inner pore, accessible from the cytoplasmic opening. Binding of drug molecules to these channels depends on their conformation, with the drugs generally having a higher affinity for the open and inactivated channel states that are induced by membrane depolarization. As a result, the effective potency of these drugs for blocking impulses increases during high-frequency repetitive firing and also under slow depolarization, such as occurs at a region of nerve injury, which is often the locus for generation of abnormal, pain-related ectopic impulses. At distal and central terminals the inhibition of voltage-gated calcium channels by local anesthetics will suppress neurogenic inflammation and the release of neurotransmitters. Actions on receptors that contribute to nociceptive transduction, such as TRPV1 and the bradykinin B2 receptor, provide an independent mode of analgesia. In the spinal cord, where local anesthetics are present during epidural or intrathecal anesthesia, inhibition of inotropic receptors, such as those for glutamate, by local anesthetics further interferes with neuronal transmission. Activation of spinal cord mitogen-activated protein (MAP) kinases, which are essential for the hyperalgesia following injury or incision and occur in both neurons and glia, is inhibited by spinal local anesthetics. Many G protein-coupled receptors are susceptible to local anesthetics, with particular sensitivity of those coupled via the Gq alpha-subunit. Local anesthetics are also infused intravenously to yield plasma concentrations far below those that block normal action potentials, yet that are frequently effective at reversing neuropathic pain. Thus, local anesthetics modify a variety of neuronal membrane channels and receptors, leading to what is probably a synergistic mixture of analgesic mechanisms to achieve effective clinical analgesia.
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Affiliation(s)
- F Yanagidate
- Pain Research Center, BWH/MRB611, 75 Francis Street, Boston, MA 02115-6110, USA
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24
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Deng PY, Lei S. Long-term depression in identified stellate neurons of juvenile rat entorhinal cortex. J Neurophysiol 2006; 97:727-37. [PMID: 17135466 DOI: 10.1152/jn.01089.2006] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The entorhinal cortex (EC) serves as a gateway to the hippocampus and plays a pivotal role in memory processing in the brain. Superficial layers of the EC convey the cortical input projections to the hippocampus, whereas deep layers of the EC relay hippocampal output projections back to the superficial layers of the EC or to other cortical regions. Whereas the EC expresses long-term potentiation (LTP) and depression (LTD), the underlying cellular and molecular mechanisms have not been determined. Because the axons of the stellate neurons in layer II of the EC form the perforant path that innervates the dentate gyrus granule cells of the hippocampus, we studied the mechanisms underlying the long-term plasticity in identified stellate neurons. Application of high-frequency stimulation (100 Hz for 1 s, repeated 3 times at an interval of 10 s) or forskolin (50 microM) failed to induce significant changes in synaptic strength, whereas application of pairing (presynaptic stimulation at 0.33 Hz paired with postsynaptic depolarization from -60 to -10 mV for 5 min) or low-frequency stimulation (LFS, 1 Hz for 15 min) paradigm-induced LTD. Pairing- or LFS-induced LTDs were N-methyl-D-aspartate receptor-dependent and occluded each other suggesting that they have the similar cellular mechanism. Pairing-induced LTD required the activity of calcineurin and involved AMPA receptor endocytosis that required the function of ubiquitin-proteasome system. Our study provides a cellular mechanism that might in part explain the role of the EC in memory.
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Affiliation(s)
- Pan-Yue Deng
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
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Amir R, Argoff CE, Bennett GJ, Cummins TR, Durieux ME, Gerner P, Gold MS, Porreca F, Strichartz GR. The Role of Sodium Channels in Chronic Inflammatory and Neuropathic Pain. THE JOURNAL OF PAIN 2006; 7:S1-29. [PMID: 16632328 DOI: 10.1016/j.jpain.2006.01.444] [Citation(s) in RCA: 243] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2005] [Revised: 01/13/2006] [Accepted: 01/20/2006] [Indexed: 11/25/2022]
Abstract
UNLABELLED Clinical and experimental data indicate that changes in the expression of voltage-gated sodium channels play a key role in the pathogenesis of neuropathic pain and that drugs that block these channels are potentially therapeutic. Clinical and experimental data also suggest that changes in voltage-gated sodium channels may play a role in inflammatory pain, and here too sodium-channel blockers may have therapeutic potential. The sodium-channel blockers of interest include local anesthetics, used at doses far below those that block nerve impulse propagation, and tricyclic antidepressants, whose analgesic effects may at least partly be due to blockade of sodium channels. Recent data show that local anesthetics may have pain-relieving actions via targets other than sodium channels, including neuronal G protein-coupled receptors and binding sites on immune cells. Some of these actions occur with nanomolar drug concentrations, and some are detected only with relatively long-term drug exposure. There are 9 isoforms of the voltage-gated sodium channel alpha-subunit, and several of the isoforms that are implicated in neuropathic and inflammatory pain states are expressed by somatosensory primary afferent neurons but not by skeletal or cardiovascular muscle. This restricted expression raises the possibility that isoform-specific drugs might be analgesic and lacking the cardiotoxicity and neurotoxicity that limit the use of current sodium-channel blockers. PERSPECTIVE Changes in the expression of neuronal voltage-gated sodium channels may play a key role in the pathogenesis of both chronic neuropathic and chronic inflammatory pain conditions. Drugs that block these channels may have therapeutic efficacy with doses that are far below those that impair nerve impulse propagation or cardiovascular function.
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Affiliation(s)
- Ron Amir
- Department of Cell and Animal Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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Arias RL, Bowlby MR. Pharmacological characterization of antiepileptic drugs and experimental analgesics on low magnesium-induced hyperexcitability in rat hippocampal slices. Brain Res 2005; 1047:233-44. [PMID: 15907811 DOI: 10.1016/j.brainres.2005.04.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 04/18/2005] [Accepted: 04/19/2005] [Indexed: 11/25/2022]
Abstract
Perfusion of acute hippocampal slices with stimulatory buffers has long been known to induce rhythmic, large amplitude, synchronized spontaneous neuronal bursting in areas CA1 and CA3. The characteristics of this model of neuronal hyperexcitability were investigated in this study, particularly with respect to the activity of antiepileptic drugs and compounds representing novel mechanisms of analgesic action. Toward that end, low Mg(2+)/high K(+)-induced spontaneous activity was quantified by a virtual instrument designed for the digitization and analysis of bursting activity. Uninterrupted streams of extracellular field potentials were digitized and analyzed in 10-s sweeps, yielding four quantified parameters of neuronal hyperexcitability. Following characterization of the temporal stability of low Mg(2+)/high K(+)-induced hyperexcitability, compounds representing a diversity of functional mechanisms were tested for their effectiveness in reversing this activity. Of the four antiepileptic drugs tested in this model, only phenytoin proved ineffective, while valproate, gabapentin and carbamazepine varied in their potencies, with only the latter drug proving to be completely efficacious. In addition, three investigational compounds having analgesic potential were examined: ZD-7288, a blocker of HCN channels; EAA-090, an NMDA antagonist; and WAY-132983, a muscarinic agonist. Each of these compounds showed strong efficacy by completely blocking spontaneous bursting activity, along with potency greater than that of the antiepileptic drugs. These data indicate that pharmacological agents with varying mechanisms of action are able to block low Mg(2+)/high K(+)-induced hyperexcitability, and thus this model may represent a useful tool for identifying novel agents and mechanisms involved in epilepsy and neuropathic pain.
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Affiliation(s)
- Robert L Arias
- Discovery Neuroscience, Wyeth Research, CN8000 Room 1513, Princeton, NJ 08543-8000, USA.
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