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Montigné E, Balayssac D. Exploring Cholinergic Compounds for Peripheral Neuropathic Pain Management: A Comprehensive Scoping Review of Rodent Model Studies. Pharmaceuticals (Basel) 2023; 16:1363. [PMID: 37895835 PMCID: PMC10609809 DOI: 10.3390/ph16101363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/01/2023] [Accepted: 09/14/2023] [Indexed: 10/29/2023] Open
Abstract
Neuropathic pain affects about 7-8% of the population, and its management still poses challenges with unmet needs. Over the past decades, researchers have explored the cholinergic system (muscarinic and nicotinic acetylcholine receptors: mAChR and nAChR) and compounds targeting these receptors as potential analgesics for neuropathic pain management. This scoping review aims to provide an overview of studies on peripheral neuropathic pain (PNP) in rodent models, exploring compounds targeting cholinergic neurotransmission. The inclusion criteria were original articles on PNP in rodent models that explored the use of compounds directly targeting cholinergic neurotransmission and reported results of nociceptive behavioral assays. The literature search was performed in the PubMed and Web of Science databases (1 January 2000-22 April 2023). The selection process yielded 82 publications, encompassing 62 compounds. The most studied compounds were agonists of α4β2 nAChR and α7 nAChR, and antagonists of α9/α10 nAChR, along with those increasing acetylcholine and targeting mAChRs. Studies mainly reported antinociceptive effects in traumatic PNP models, and to a lesser extent, chemotherapy-induced neuropathy or diabetic models. These preclinical studies underscore the considerable potential of cholinergic compounds in the management of PNP, warranting the initiation of clinical trials.
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Affiliation(s)
- Edouard Montigné
- INSERM, U1107, NEURO-DOL, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France;
| | - David Balayssac
- INSERM, U1107, NEURO-DOL, Université Clermont Auvergne, Direction de la Recherche Clinique et de l’Innovation, CHU Clermont-Ferrand, F-63000 Clermont-Ferrand, France
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Akinola LS, Bagdas D, Alkhlaif Y, Jackson A, Gurdap CO, Rahimpour E, Carroll FI, Papke RL, Damaj MI. Pharmacological characterization of 5-iodo-A-85380, a β2-selective nicotinic receptor agonist, in mice. J Psychopharmacol 2022; 36:1280-1293. [PMID: 36321267 PMCID: PMC9817006 DOI: 10.1177/02698811221132214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Because of their implications in several pathological conditions, α4β2* nicotinic acetylcholine receptors (nAChRs) are potential targets for the treatment of nicotine dependence, pain, and many psychiatric and neurodegenerative diseases. However, they exist in various subtypes, and finding selective tools to investigate them has proved challenging. The nicotinic receptor agonist, 5-iodo-A-85380 (5IA), has helped in delineating the function of β2-containing subtypes in vitro; however, much is still unknown about its behavioral effects. Furthermore, its effectiveness on α6-containing subtypes is limited. AIMS To investigate the effects of 5IA on nociception (formalin, hot-plate, and tail-flick tests), locomotion, hypothermia, and conditioned reward after acute and repeated administration, and to examine the potential role of β2 and α6 nAChR subunits in these effects. Lastly, its selectivity for expressed low sensitivity (LS) and high sensitivity (HS) α4β2 receptors is investigated. RESULTS 5IA dose-dependently induced hypothermia, locomotion suppression, conditioned place preference, and antinociception (only in the formalin test but not in the hot-plate or tail-flick tests). Furthermore, these effects were mediated by β2 but not α6 nicotinic subunits. Finally, we show that 5-iodo-A-85380 potently activates both stoichiometries of α4β2 nAChRs with differential efficacies, being a full agonist on HS α4(2)β2(3) nAChRs, and a partial agonist on LS α4(3)β2(2) nAChRs and α6-containing subtypes as well.
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Affiliation(s)
- Lois S Akinola
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
| | - Deniz Bagdas
- Department of Psychiatry, School of Medicine, Yale University, USA
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - Yasmin Alkhlaif
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
| | - Asti Jackson
- Department of Psychiatry, School of Medicine, Yale University, USA
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - Cenk O Gurdap
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, Sweden
| | - Elnaz Rahimpour
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - F Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, USA
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
- Translational Research Initiative for Pain and Neuropathy, Medical College of Virginia Campus, Virginia Commonwealth University, USA
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3
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Pastori V, D'Aloia A, Blasa S, Lecchi M. Serum-deprived differentiated neuroblastoma F-11 cells express functional dorsal root ganglion neuron properties. PeerJ 2019; 7:e7951. [PMID: 31687277 PMCID: PMC6825413 DOI: 10.7717/peerj.7951] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022] Open
Abstract
The isolation and culture of dorsal root ganglion (DRG) neurons cause adaptive changes in the expression and regulation of ion channels, with consequences on neuronal excitability. Considering that not all neurons survive the isolation and that DRG neurons are heterogeneous, it is difficult to find the cellular subtype of interest. For this reason, researchers opt for DRG-derived immortal cell lines to investigate endogenous properties. The F-11 cell line is a hybridoma of embryonic rat DRG neurons fused with the mouse neuroblastoma line N18TG2. In the proliferative condition, F-11 cells do not display a gene expression profile correspondent with specific subclasses of sensory neurons, but the most significant differences when compared with DRGs are the reduction of voltage-gated sodium, potassium and calcium channels, and the small amounts of TRPV1 transcripts. To investigate if functional properties of mature F-11 cells showed more similarities with those of isolated DRG neurons, we differentiated them by serum deprivation. Potassium and sodium currents significantly increased with differentiation, and biophysical properties of tetrodotoxin (TTX)-sensitive currents were similar to those characterized in small DRG neurons. The analysis of the voltage-dependence of calcium currents demonstrated the lack of low threshold activated components. The exclusive expression of high threshold activated Ca2+ currents and of TTX-sensitive Na+ currents correlated with the generation of a regular tonic electrical activity, which was recorded in the majority of the cells (80%) and was closely related to the activity of afferent TTX-sensitive A fibers of the proximal urethra and the bladder. Responses to capsaicin and substance P were also recorded in ~20% and ~80% of cells, respectively. The percentage of cells responsive to acetylcholine was consistent with the percentage referred for rat DRG primary neurons and cell electrical activity was modified by activation of non-NMDA receptors as for embryonic DRG neurons. These properties and the algesic profile (responses to pH5 and sensitivity to both ATP and capsaicin), proposed in literature to define a sub-classification of acutely dissociated rat DRG neurons, suggest that differentiated F-11 cells express receptors and ion channels that are also present in sensory neurons.
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Affiliation(s)
- Valentina Pastori
- Department of Biotechnology and Biosciences and Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
| | - Alessia D'Aloia
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Stefania Blasa
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | - Marzia Lecchi
- Department of Biotechnology and Biosciences and Milan Center for Neuroscience, University of Milano-Bicocca, Milan, Italy
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Freitas KC, Carroll FI, Negus SS. Effects of nicotinic acetylcholine receptor agonists in assays of acute pain-stimulated and pain-depressed behaviors in rats. J Pharmacol Exp Ther 2016; 355:341-50. [PMID: 26359313 DOI: 10.1124/jpet.115.226803] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Agonists at nicotinic acetylcholine receptors (nAChRs) constitute one drug class being evaluated as candidate analgesics. Previous preclinical studies have implicated α4β2 and α7 nAChRs as potential mediators of the antinociceptive effects of (–)-nicotine hydrogen tartrate (nicotine) and other nAChR agonists; however, these studies have relied exclusively on measures of pain-stimulated behavior, which can be defined as behaviors that increase in frequency, rate, or intensity after presentation of a noxious stimulus. Pain is also associated with depression of many behaviors, and drug effects can differ in assays of pain-stimulated versus pain-depressed behavior. Accordingly, this study compared the effects of nicotine, the selective α4/6β2 agonist 5-(123I)iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380), and the selective α7 agonist N-(3R)-1-azabicyclo(2.2.2)oct-3-yl-4-chlorobenzamide in assays of pain-stimulated and pain-depressed behavior in male Sprague-Dawley rats. Intraperitoneal injection of dilute lactic acid served as an acute noxious stimulus to either stimulate a stretching response or depress the operant responding, which is maintained by electrical brain stimulation in an intracranial self-stimulation (ICSS) procedure. Nicotine produced a dose-dependent, time-dependent, and mecamylamine-reversible blockade of both acid-stimulated stretching and acid-induced depression of ICSS. 5-I-A-85380 also blocked both acid-stimulated stretching and acid-induced depression of ICSS, whereas N-(3R)-1-azabicyclo(2.2.2)oct-3-yl-4-chlorobenzamide produced no effect in either procedure. Both nicotine and 5-I-A-85380 were ≥10-fold more potent in blocking the acid-induced depression of ICSS than in blocking the acid-induced stimulation of stretching. These results suggest that stimulation of α4β2 and/or α6β2 nAChRs may be especially effective to alleviate the signs of pain-related behavioral depression in rats; however, nonselective behavioral effects may contribute to apparent antinociception.
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Affiliation(s)
- Kelen C Freitas
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Xanthos DN, Beiersdorf JW, Thrun A, Ianosi B, Orr-Urtreger A, Huck S, Scholze P. Role of α5-containing nicotinic receptors in neuropathic pain and response to nicotine. Neuropharmacology 2015; 95:37-49. [PMID: 25725336 DOI: 10.1016/j.neuropharm.2015.02.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 02/03/2015] [Accepted: 02/10/2015] [Indexed: 11/26/2022]
Abstract
Nicotinic receptors in the central nervous system (nAChRs) are known to play important roles in pain processing and modulate behavioral responses to analgesic drugs, including nicotine. The presence of the α5-neuronal nicotinic accessory subunit in the nicotinic receptor complex is increasingly understood to modulate reward and aversive states, addiction, and possibly pathological pain. In the current study, using α5-knockout (KO) mice and subunit-specific antibodies, we assess the role of α5-containing neuronal nicotinic receptors in neuropathic pain and in the analgesic response to nicotine. After chronic constriction injury (CCI) or partial sciatic nerve ligation (PSNL), no differences in mechanical, heat, or cold hyperalgesia were found in wild-type (WT) versus α5-KO littermate mice. The number of α5-containing nAChRs was decreased (rather than increased) after CCI in the spinal cord and in the thalamus. Nevertheless, thermal analgesic response to nicotine was marginally reduced in CCI α5-KO mice at 4 days after CCI, but not at later timepoints or after PSNL. Interestingly, upon daily intermittent nicotine injections in unoperated mice, WT animals developed tolerance to nicotine-induced analgesia to a larger extent than α5-KO mice. Our results suggest that α5-containing nAChRs mediate analgesic tolerance to nicotine but do not play a major role in neuropathic pain.
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Affiliation(s)
- Dimitris N Xanthos
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria.
| | - Johannes W Beiersdorf
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria
| | - Ariane Thrun
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria
| | - Bogdan Ianosi
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria
| | - Avi Orr-Urtreger
- The Genetic Institute, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel; The Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Sigismund Huck
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Austria.
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Zhang XL, Albers KM, Gold MS. Inflammation-induced increase in nicotinic acetylcholine receptor current in cutaneous nociceptive DRG neurons from the adult rat. Neuroscience 2015; 284:483-499. [PMID: 25453771 PMCID: PMC4268410 DOI: 10.1016/j.neuroscience.2014.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/02/2014] [Accepted: 10/09/2014] [Indexed: 12/29/2022]
Abstract
The goals of the present study were to determine (1) the properties of the nicotinic acetylcholine receptor (nAChR) currents in rat cutaneous dorsal root ganglion (DRG) neurons; (2) the impact of nAChR activation on the excitability of cutaneous DRG neurons; and (3) the impact of inflammation on the density and distribution of nAChR currents among cutaneous DRG neurons. Whole-cell patch-clamp techniques were used to study retrogradely labeled DRG neurons from naïve and complete Freund's adjuvant inflamed rats. Nicotine-evoked currents were detectable in ∼70% of the cutaneous DRG neurons, where only one of two current types, fast or slow currents based on rates of activation and inactivation, was present in each neuron. The biophysical and pharmacological properties of the fast current were consistent with nAChRs containing an α7 subunit while those of the slow current were consistent with nAChRs containing α3/β4 subunits. The majority of small diameter neurons with fast current were IB4- while the majority of small diameter neurons with slow current were IB4+. Preincubation with nicotine (1 μM) produced a transient (1 min) depolarization and increase in the excitability of neurons with fast current and a decrease in the amplitude of capsaicin-evoked current in neurons with slow current. Inflammation increased the current density of both slow and fast currents in small diameter neurons and increased the percentage of neurons with the fast current. With the relatively selective distribution of nAChR currents in putative nociceptive cutaneous DRG neurons, our results suggest that the role of these receptors in inflammatory hyperalgesia is likely to be complex and dependent on the concentration and timing of acetylcholine release in the periphery.
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Affiliation(s)
- X-L Zhang
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - K M Albers
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, United States; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - M S Gold
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213, United States; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213, United States.
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7
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Umana IC, Daniele CA, McGehee DS. Neuronal nicotinic receptors as analgesic targets: it's a winding road. Biochem Pharmacol 2013; 86:1208-14. [PMID: 23948066 DOI: 10.1016/j.bcp.2013.08.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/01/2013] [Accepted: 08/01/2013] [Indexed: 12/12/2022]
Abstract
Along with their well known role in nicotine addiction and autonomic physiology, neuronal nicotinic receptors (nAChRs) also have profound analgesic effects in animal models and humans. This is not a new idea, even in the early 1500s, soon after tobacco was introduced to the new world, its proponents listed pain relief among the beneficial properties of smoking. In recent years, analgesics that target specific nAChR subtypes have shown highly efficacious antinociceptive properties in acute and chronic pain models. To date, the side effects of these drugs have precluded their advancement to the clinic. This review summarizes the recent efforts to identify novel analgesics that target nAChRs, and outlines some of the key neural substrates that contribute to these physiological effects. There remain many unanswered mechanistic questions in this field, and there are still compelling reasons to explore neuronal nAChRs as targets for the relief of pain.
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Affiliation(s)
- Iboro C Umana
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, IL, United States
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8
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Safieh-Garabedian B, Oz M, Bey RM, Shamaa F, Ashoor A, El-Agnaf OM, Saadé NE. Involvement of the α7-nicotinic acetylcholine receptors in the anti-inflammatory action of the thymulin-related peptide (PAT). Neuroscience 2013; 250:455-66. [PMID: 23880090 DOI: 10.1016/j.neuroscience.2013.07.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/11/2013] [Accepted: 07/14/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND PURPOSE Peptide analog of thymulin (PAT) has been shown to have anti-hyperalgesic and anti-inflammatory properties in animal models of inflammation. Recent reports suggest that the peripheral cholinergic system has an anti-inflammatory role mediated by α7-nicotinic acetylcholine receptor (α7-nAChR). Our aim is to investigate whether the action of PAT is mediated, via the cholinergic pathway. EXPERIMENTAL APPROACH The anti-hyperalgesic and anti-inflammatory action of PAT was assessed in rat models of inflammatory nociceptive hyperactivity (carrageenan and endotoxin) and in a mice air-pouch model for localized inflammation, respectively; the possible attenuation of PAT's effects by pretreatment with the α7-nAchR specific antagonist methyllycaconitine citrate (MLA) was also investigated. In another series of experiments, using two electrode recordings, the effect of PAT on the α7-nAChRs, expressed in Xenopus Oocytes, was also determined. KEY RESULTS Administration of PAT reversed inflammatory nociceptive hyperactivity and cold and tactile hyperactivity in rats. This effect was partially or totally prevented by MLA, as assessed by different behavioral pain tests. Treatment with PAT also reduced the alteration of cytokines and NGF levels by carrageenan injection in the mouse air pouch model; this effect was partially antagonized by MLA. Electrophysiological recording demonstrated that PAT significantly potentiated the α7-nAchR expressed in Xenopus Oocytes. These effects were not observed when a control peptide, with a reverse sequence (rPAT), was utilized. CONCLUSIONS AND IMPLICATIONS The behavioral and electrophysiological observations described in this report demonstrate that PAT mediates, at least partially, its anti-inflammatory action by potentiating the α7-nAChR. These results indicate that PAT has a potential for new therapeutic applications as anti-inflammatory and analgesic agent.
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Affiliation(s)
- B Safieh-Garabedian
- Department of Natural Sciences and Public Health, Zayed University, Abu Dhabi, United Arab Emirates.
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Nirogi R, Goura V, Abraham R, Jayarajan P. α4β2* neuronal nicotinic receptor ligands (agonist, partial agonist and positive allosteric modulators) as therapeutic prospects for pain. Eur J Pharmacol 2013; 712:22-9. [PMID: 23660369 DOI: 10.1016/j.ejphar.2013.04.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/15/2013] [Accepted: 04/18/2013] [Indexed: 01/31/2023]
Abstract
α4β2* neuronal nicotinic acetylcholine receptor are ligand-gated ion channels and widely expressed throughout the central and peripheral nervous system. α4β2* neuronal nicotinic acetylcholine receptor play crucial role in pain signaling via modulation of multiple neurotransmitters like acetylcholine, dopamine, γ-amino butyric acid (GABA) and norepinephrine. Both spinal and supraspinal pathways are involved in the mechanisms by which α4β2* neuronal nicotinic acetylcholine receptor ligands modulate the neuropathic and inflammatory pain. Selective α4β2* neuronal nicotinic acetylcholine receptor ligands are being developed for the treatment of neuropathic and inflammatory pain as they show considerable efficacy in a wide range of preclinical pain models. Agonists/partial agonists of α4β2* neuronal nicotinic acetylcholine receptor show efficacy in animal models of pain and their anti-nociceptive properties are blocked by nicotinic antagonists. Positive allosteric modulators are being developed with the aim to increase the potency or therapeutic window of agonists/partial agonists. Accumulating evidences suggest that anti-nociceptive effects of nicotinic acetylcholine receptor ligands may not be mediated solely by α4β2* neuronal nicotinic acetylcholine receptor. We have also reviewed the stage of clinical development of various α4β2* neuronal nicotinic acetylcholine receptor ligands.
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Affiliation(s)
- Ramakrishna Nirogi
- In-Vivo Pharmacology, Discovery Research, Suven Life Sciences Ltd., Serene Chambers, Road No. 5, Avenue-7, Banjara Hills, Hyderabad 500034, India.
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Capim SL, Carneiro PH, Castro PC, Barros MR, Marinho BG, Vasconcellos ML. Design, Prins-cyclization reaction promoting diastereoselective synthesis of 10 new tetrahydropyran derivatives and in vivo antinociceptive evaluations. Eur J Med Chem 2012; 58:1-11. [DOI: 10.1016/j.ejmech.2012.09.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 09/24/2012] [Accepted: 09/27/2012] [Indexed: 11/28/2022]
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Hama A. The challenge of understanding peripherally mediated antinociception: commentary on a paper by Chung et al. (2012, this issue). Eur J Pain 2012; 16:949-50. [PMID: 22528949 DOI: 10.1002/j.1532-2149.2012.00160.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- A Hama
- University of Miami Miller School of Medicine, FL 33136, USA.
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Nirogi R, Jabaris SL, Jayarajan P, Abraham R, Shanmuganathan D, Rasheed MA, Royapalley PK, Goura V. Antinociceptive activity of α4β2* neuronal nicotinic receptor agonist A-366833 in experimental models of neuropathic and inflammatory pain. Eur J Pharmacol 2011; 668:155-62. [PMID: 21756895 DOI: 10.1016/j.ejphar.2011.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/02/2011] [Accepted: 06/15/2011] [Indexed: 01/12/2023]
Abstract
Nerve injury, diabetes and cancer therapies are often associated with painful neuropathy. The mechanism underlying neuropathic pain remains poorly understood. The current therapies have limited efficacy and are associated with dose-limiting side effects. Compounds which act at nicotinic acetylcholine receptors have also been reported to show antinociceptive activity. Among those, tebanicline (ABT-594) a potent nicotinic acetylcholine receptor agonist demonstrated analgesic effects across a broad range of preclinical models of nociceptive and neuropathic pain. Another nicotinic acetylcholine receptor agonist, 5-[(1R,5S)-3,6-Diazabicyclo[3.2.0]heptan-6-yl]nicotinonitrile (A-366833) from the same group produced significant antinociceptive effects in writhing pain (abdominal constriction), acute thermal pain (hot box), persistent chemical pain (formalin induced) and neuropathic pain. In the present study, we have demonstrated the efficacy of A-366833 in rat models of chronic constriction injury, partial sciatic nerve ligation, spinal nerve ligation, diabetes, chemotherapy induced neuropathic pain and complete Freund's adjuvant induced inflammatory pain. A-366833 (1, 3 and 6 mg/kg) produced significant antihyperalgesic effects in partial sciatic nerve ligation, chronic constriction injury and spinal nerve ligation models. In the diabetic and chemotherapy induced neuropathic models compound exerted antinociceptive activity and reduction in the mechanical hyperalgesia was observed. A-366833 dose dependently attenuated mechanical hyperalgesia in complete Freund's adjuvant induced inflammatory pain model. These results demonstrated broad-spectrum antinociceptive properties of A-366833 in both neuropathic and inflammatory pain models.
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Affiliation(s)
- Ramakrishna Nirogi
- Department of Pharmacology, Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road No 5, Avenue-7, Banjara Hills, Hyderabad, 500034, India.
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Hsieh GC, Pai M, Chandran P, Hooker BA, Zhu CZ, Salyers AK, Wensink EJ, Zhan C, Carroll WA, Dart MJ, Yao BB, Honore P, Meyer MD. Central and peripheral sites of action for CB₂ receptor mediated analgesic activity in chronic inflammatory and neuropathic pain models in rats. Br J Pharmacol 2011; 162:428-40. [PMID: 20880025 DOI: 10.1111/j.1476-5381.2010.01046.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Cannabinoid CB₂ receptor activation by selective agonists has been shown to produce analgesic effects in preclinical models of inflammatory and neuropathic pain. However, mechanisms underlying CB₂-mediated analgesic effects remain largely unknown. The present study was conducted to elucidate the CB₂ receptor expression in 'pain relevant' tissues and the potential sites of action of CB₂ agonism in rats. EXPERIMENTAL APPROACH Expression of cannabinoid receptor mRNA was evaluated by quantitative RT-PCR in dorsal root ganglia (DRGs), spinal cords, paws and several brain regions of sham, chronic inflammatory pain (CFA) and neuropathic pain (spinal nerve ligation, SNL) rats. The sites of CB₂ mediated antinociception were evaluated in vivo following intra-DRG, intrathecal (i.t.) or intraplantar (i.paw) administration of potent CB₂-selective agonists A-836339 and AM1241. KEY RESULTS CB₂ receptor gene expression was significantly up-regulated in DRGs (SNL and CFA), spinal cords (SNL) or paws (CFA) ipsilateral to injury under inflammatory and neuropathic pain conditions. Systemic A-836339 and AM1241 produced dose-dependent efficacy in both inflammatory and neuropathic pain models. Local administration of CB₂ agonists also produced significant analgesic effects in SNL (intra-DRG and i.t.) and CFA (intra-DRG) pain models. In contrast to A-836339, i.paw administration of AM-1241 dose-relatedly reversed the CFA-induced thermal hyperalgesia, suggesting that different mechanisms may be contributing to its in vivo properties. CONCLUSIONS AND IMPLICATIONS These results demonstrate that both DRG and spinal cord are important sites contributing to CB₂ receptor-mediated analgesia and that the changes in CB₂ receptor expression play a crucial role for the sites of action in regulating pain perception.
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Affiliation(s)
- Gin C Hsieh
- Global Pharmaceutical Research & Development, Abbott Laboratories, Abbott Park, IL 60064, USA.
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Maloku E, Kadriu B, Zhubi A, Dong E, Pibiri F, Satta R, Guidotti A. Selective α4β2 nicotinic acetylcholine receptor agonists target epigenetic mechanisms in cortical GABAergic neurons. Neuropsychopharmacology 2011; 36:1366-74. [PMID: 21368748 PMCID: PMC3096806 DOI: 10.1038/npp.2011.21] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 01/26/2011] [Accepted: 01/28/2011] [Indexed: 12/12/2022]
Abstract
Nicotine improves cognitive performance and attention in both experimental animals and in human subjects, including patients affected by neuropsychiatric disorders. However, the specific molecular mechanisms underlying nicotine-induced behavioral changes remain unclear. We have recently shown in mice that repeated injections of nicotine, which achieve plasma concentrations comparable to those reported in high cigarette smokers, result in an epigenetically induced increase of glutamic acid decarboxylase 67 (GAD(67)) expression. Here we explored the impact of synthetic α(4)β(2) and α(7) nAChR agonists on GABAergic epigenetic parameters. Varenicline (VAR), a high-affinity partial agonist at α(4)β(2) and a lower affinity full agonist at α(7) neuronal nAChR, injected in doses of 1-5 mg/kg/s.c. twice daily for 5 days, elicited a 30-40% decrease of cortical DNA methyltransferase (DNMT)1 mRNA and an increased expression of GAD(67) mRNA and protein. This upregulation of GAD(67) was abolished by the nAChR antagonist mecamylamine. Furthermore, the level of MeCP(2) binding to GAD(67) promoters was significantly reduced following VAR administration. This effect was abolished when VAR was administered with mecamylamine. Similar effects on cortical DNMT1 and GAD(67) expression were obtained after administration of A-85380, an agonist that binds to α(4)β(2) but has negligible affinity for α(3)β(4) or α(7) subtypes containing nAChR. In contrast, PNU-282987, an agonist of the homomeric α(7) nAChR, failed to decrease cortical DNMT1 mRNA or to induce GAD(67) expression. The present study suggests that the α(4)β(2) nAChR agonists may be better suited to control the epigenetic alterations of GABAergic neurons in schizophrenia than the α(7) nAChR agonists.
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Affiliation(s)
- Ekrem Maloku
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Bashkim Kadriu
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Adrian Zhubi
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Erbo Dong
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Fabio Pibiri
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Rosalba Satta
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
| | - Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA
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Fischer G, Kostic S, Nakai H, Park F, Sapunar D, Yu H, Hogan Q. Direct injection into the dorsal root ganglion: technical, behavioral, and histological observations. J Neurosci Methods 2011; 199:43-55. [PMID: 21540055 DOI: 10.1016/j.jneumeth.2011.04.021] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 04/12/2011] [Accepted: 04/14/2011] [Indexed: 10/18/2022]
Abstract
Direct injection of agents into the dorsal root ganglia (DRGs) offers the opportunity to manipulate sensory neuron function at a segmental level to explore pathophysiology of painful conditions. However, there is no described method that has been validated in detail for such injections in adult rats. We have found that 2 μl of dye injected through a pulled glass pipette directly into the distal DRG, exposed by a minimal foraminotomy, produces complete filling of the DRG with limited extension into the spinal roots. Injection into the spinal nerve required 3 μl to achieve comparable DRG filling, produced preferential spread into the ventral root, and was accompanied by substantial leakage of injected solution from the injection site. Injections into the sciatic nerve of volumes up to 10 μl did not reach the DRG. Transient hypersensitivity to mechanical stimulation at threshold (von Frey) and noxious levels (pin) developed after 2 μl saline injection directly into the DRG that was in part attributable to the surgical exposure procedure alone. Only minimal astrocyte activation in the spinal dorsal horn was evident after DRG saline injections. Injection of adeno-associated virus (AAV) vector conveying green fluorescent protein (GFP) transgene resulted in expression as soon as 1 day after injection into the DRG, including fibers in the spinal dorsal horn and columns. AAV injection into the DRG produced additional thermal hypersensitivity and withdrawal from the stroke of a brush and compromised motor performance. These findings demonstrate a method for selective injection of agents into single DRGs for anatomically restricted actions.
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Affiliation(s)
- Gregory Fischer
- Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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16
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Zhao X, Ye J, Sun Q, Xiong Y, Li R, Jiang Y. Antinociceptive effect of spirocyclopiperazinium salt compound LXM-15 via activating peripheral α7 nAChR and M4 mAChR in mice. Neuropharmacology 2011; 60:446-52. [DOI: 10.1016/j.neuropharm.2010.10.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 10/19/2010] [Accepted: 10/20/2010] [Indexed: 10/18/2022]
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17
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Munro G, Dyhr H, Grunnet M. Selective potentiation of gabapentin-mediated antinociception in the rat formalin test by the nicotinic acetylcholine receptor agonist ABT-594. Neuropharmacology 2010; 59:208-17. [DOI: 10.1016/j.neuropharm.2010.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 05/24/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022]
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18
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Ueda M, Iida Y, Yoneyama T, Kawai T, Ogawa M, Magata Y, Saji H. In vivo relationship between thalamic nicotinic acetylcholine receptor occupancy rates and antiallodynic effects in a rat model of neuropathic pain: Persistent agonist binding inhibits the expression of antiallodynic effects. Synapse 2010; 65:77-83. [DOI: 10.1002/syn.20819] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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19
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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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Gao B, Hierl M, Clarkin K, Juan T, Nguyen H, van der Valk M, Deng H, Guo W, Lehto SG, Matson D, McDermott JS, Knop J, Gaida K, Cao L, Waldon D, Albrecht BK, Boezio AA, Copeland KW, Harmange JC, Springer SK, Malmberg AB, McDonough SI. Pharmacological effects of nonselective and subtype-selective nicotinic acetylcholine receptor agonists in animal models of persistent pain. Pain 2010; 149:33-49. [DOI: 10.1016/j.pain.2010.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 12/16/2009] [Accepted: 01/11/2010] [Indexed: 12/20/2022]
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21
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Decker MW, Gopalakrishnan M, Meyer MD. The potential of neuronal nicotinic acetylcholine receptor agonists for treating CNS conditions. Expert Opin Drug Discov 2008; 3:1027-40. [DOI: 10.1517/17460441.3.9.1027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Chin CL, Pauly JR, Surber BW, Skoubis PD, McGaraughty S, Hradil VP, Luo Y, Cox BF, Fox GB. Pharmacological MRI in awake rats predicts selective binding of α4β2 nicotinic receptors. Synapse 2008; 62:159-68. [DOI: 10.1002/syn.20474] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Ji J, Bunnelle WH, Anderson DJ, Faltynek C, Dyhring T, Ahring PK, Rueter LE, Curzon P, Buckley MJ, Marsh KC, Kempf-Grote A, Meyer MD. A-366833: a novel nicotinonitrile-substituted 3,6-diazabicyclo[3.2.0]-heptane alpha4beta2 nicotinic acetylcholine receptor selective agonist: Synthesis, analgesic efficacy and tolerability profile in animal models. Biochem Pharmacol 2007; 74:1253-62. [PMID: 17854775 DOI: 10.1016/j.bcp.2007.08.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 08/07/2007] [Accepted: 08/08/2007] [Indexed: 11/17/2022]
Abstract
5-[(1R,5S)-3,6-Diazabicyclo[3.2.0]heptan-6-yl]nicotinonitrile (A-366833) is a novel nicotinic acetylcholine receptor (nAChR) ligand that binds to the agonist-binding site ([3H]-cytisine) with Ki value of 3.1 nM and exhibits agonist selectivity at alpha4beta2 nAChR relative to the alpha3beta4 nAChR subtype. The analgesic effects of A-366833 were examined across a variety of animal models including the mouse model of writhing pain (abdominal constriction), the rat models of acute thermal (hot box), persistent chemical (formalin) and neuropathic (spinal nerve ligation, SNL) pain. In the abdominal constriction model, A-366833 was effective at doses ranging from 0.062 to 0.62 micromol/kg (i.p.). In addition, A-366833 demonstrated significant effects in acute thermal pain (6.2-19.0 micromol/kg, i.p.), formalin (1.9-19 micromol/kg i.p.) and SNL (1.9-19 micromol/kg i.p.) models. The systemic effects of A-366833 were attenuated by pretreatment with mecamylamine (5 micromol/kg i.p.) in both the formalin and SNL models, suggesting that the analgesic effects of A-366833 in models of persistent nociceptive and neuropathic pain are mediated by activation of nAChRs. Pharmacokinetic investigations of A-366833 in rat revealed moderate brain:plasma distribution, half-life of 1.5h and excellent oral bioavailability of 73%. Comparison of peak plasma levels at the minimal effective doses across rat models of acute thermal pain, formalin and SNL with the maximal exposure that does not evoke emesis in ferret revealed therapeutic margins ranging from 6- to 22-fold. These studies indicate that compounds like A-366833 with improved agonist selectivity at alpha4beta2 vs. alpha3beta4 nAChR can elicit a broad spectrum of analgesic efficacy without concurrent adverse effects.
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Affiliation(s)
- Jianguo Ji
- Neuroscience Research, Department-R47W, Bldg-AP9A, Global Pharmaceutical Research and Development, Abbott, Abbott Park, IL 60064, USA.
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24
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Rueter LE, Donnelly-Roberts DL, Curzon P, Briggs CA, Anderson DJ, Bitner RS. A-85380: a pharmacological probe for the preclinical and clinical investigation of the alphabeta neuronal nicotinic acetylcholine receptor. CNS DRUG REVIEWS 2006; 12:100-12. [PMID: 16958984 PMCID: PMC6494138 DOI: 10.1111/j.1527-3458.2006.00100.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A-85380 [3-(2(s)-azetidinylmethoxy) pyridine] is a neuronal nicotinic acetylcholine receptor (nAChR) agonist that has been a useful tool in the investigation of the function of nAChRs in both preclinical and clinical studies. Amongst nAChR subtypes, A-85380 shows selectivity for the alpha(4)beta(2) vs. the alpha(7) or alpha(1)beta(1)deltagamma nAChRs. In functional in vitro cation flux assays, A-85380 is a potent and full agonist. A-85380 has a broad-spectrum analgesic profile with efficacy in acute, persistent, and neuropathic pain models. As demonstrated using selective nAChR antagonists or alpha(4) antisense, the alpha(4)beta(2) nAChR mediates the analgesic effects of A-85380. Interestingly, the site of action depends upon the type of pain as antinociception is mediated by descending inhibition into the spinal cord whereas anti-allodynia in neuropathic pain is mediated at both central and peripheral sites. Radiolabelled forms of A-85380 have been developed and shown to be safe for use in vivo in humans. In clinical studies using positron and photon emission tomography, marked decreases in alpha(4)beta(2) nAChRs have been seen in patients with Parkinson's and Alzheimer's disease. Although not developed as a therapeutic agent, A-85380 has proven to be an important component in the development of novel nAChR ligands for the treatment of pain and other disorders.
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Affiliation(s)
- Lynne E Rueter
- Abbott Laboratories, Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Park, IL, USA.
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25
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Meyer MD. Neuronal nicotinic acetylcholine receptors as a target for the treatment of neuropathic pain. Drug Dev Res 2006. [DOI: 10.1002/ddr.20099] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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26
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Skoubis PD, Hradil V, Chin CL, Luo Y, Fox GB, McGaraughty S. Mapping brain activity following administration of a nicotinic acetylcholine receptor agonist, ABT-594, using functional magnetic resonance imaging in awake rats. Neuroscience 2006; 137:583-91. [PMID: 16289887 DOI: 10.1016/j.neuroscience.2005.08.072] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 08/18/2005] [Accepted: 08/30/2005] [Indexed: 11/18/2022]
Abstract
Administration of ABT-594, a potent agonist for nicotinic acetylcholine receptors with selectivity for the alpha4beta2 receptor subtype, is known to modulate a diverse array of behaviors including those associated with nociception, anxiety and motor function. In this study, we sought to gain insight into the neural actions of ABT-594, in vivo, by conducting functional magnetic resonance imaging in awake and anesthetized rats. Using T(2)*-weighted gradient echo imaging and an ultrasmall superparamagnetic iron oxide contrast agent, functional imaging was conducted on a 4.7 T magnet to measure changes in relative cerebral blood volume. In awake, restrained, male Sprague-Dawley rats that were acclimated to the imaging environment, injection of ABT-594 (0.03-0.3 micromol/kg, i.v.) evoked changes to relative cerebral blood volume in several neural regions including the cingulate, somatosensory, motor, auditory, and pre-frontal cortices as well as the thalamus and the periaqueductal gray/dorsal raphe. These effects were typically bimodal with significant decreases in relative cerebral blood volume at the 0.03 micromol/kg dose and increases at the higher doses (0.1 and 0.3 micromol/kg). The decreases and increases in relative cerebral blood volume were often observed within the same region, but triggered by different doses. Both increases and decreases in relative cerebral blood volume were blocked by pretreatment with the noncompetitive nicotinic acetylcholine receptor antagonist, mecamylamine (5 micromol/kg, i.p.) in awake rats. Administration of ABT-594 (0.1 micromol/kg, i.v.) to alpha-chloralose-anesthetized rats did not significantly alter relative cerebral blood volume in any brain region suggesting an anesthetic-related interference with the effects of ABT-594. The neural regions affected by administration of ABT-594 corresponded well to the known pre-clinical behavioral profile for this compound, and demonstrate the utility of using functional magnetic resonance imaging in awake animals to study pharmacological action.
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Affiliation(s)
- P D Skoubis
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, R4CL, AP9-1, 100 Abbott Park Road, Abbott Park, IL 60064-6118, USA
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27
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Fucile S, Sucapane A, Eusebi F. Ca2+ permeability of nicotinic acetylcholine receptors from rat dorsal root ganglion neurones. J Physiol 2005; 565:219-28. [PMID: 15760934 PMCID: PMC1464485 DOI: 10.1113/jphysiol.2005.084871] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ca2+ entry through neuronal nicotinic ACh receptors (nAChRs) modulates many biological processes in nervous tissue. In order to study the functional role of nAChRs in peripheral sensory signalling, we measured their Ca2+ permeability in rat dorsal root ganglion (DRG) neurones, and analysed the effects of nAChR-mediated Ca2+ influx on the function of the vanilloid receptor TRPV1. The fractional Ca2+ current (P(f), i.e. the percentage of current carried by Ca2+ ions) flowing through nAChR channels was measured by Ca2+ imaging fluorescence microscopy in combination with the patch-clamp technique. Functional nAChRs were expressed in a subset of adult DRG neurones (about 24% of the cells), typically with small to medium size as measured by their capacitance (40 +/- 3 pF). In most cells, ACh evoked slowly desensitizing currents, insensitive to methyllycaconitine (MLA, 10 nm), a potent antagonist of homomeric nAChRs. Fast decaying currents, probably mediated by alpha7*-nAChRs (i.e. native alpha7-containing nAChRs), were observed in 15% of ACh-responsive cells, in which slowly decaying currents, mediated by heteromeric nAChRs, were simultaneously present. The nAChRs of adult DRG neurones exhibited a P(f) value of 2.2 +/- 0.6% in the presence of MLA and 1.9 +/- 0.6% (P > 0.1) in the absence of MLA, indicating that homomeric MLA-sensitive nAChRs do not contribute to Ca2+ entry into adult DRG neurones. Conversely, 10% of neonatal DRG neurones showed ACh-evoked currents completely blocked by MLA. In these neurones, nAChRs showed a larger P(f) value (9.5 +/- 1.5%), indicating the expression of bona fide alpha7*-nAChRs. Finally, we report that Ca2+ influx through nAChRs in adult DRG neurones negatively modulated the TRPV1-mediated responses, representing a possible mechanism underlying the analgesic properties of nicotinic agonists on sensory neurones.
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Affiliation(s)
- Sergio Fucile
- Istituto Pasteur Fondazione Cenci-Bolognetti and Dipartimento di Fisiologia Umana e Farmacologia, Centro di Eccellenza Biologia e Medicina Molecolare, Università di Roma La Sapienza, Roma, Italy.
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28
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Bunnelle WH, Decker MW. Neuronal nicotinic acetylcholine receptor ligands as potential analgesics. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.13.7.1003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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29
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Lynch JJ, Wade CL, Mikusa JP, Decker MW, Honore P. ABT-594 (a nicotinic acetylcholine agonist): anti-allodynia in a rat chemotherapy-induced pain model. Eur J Pharmacol 2005; 509:43-8. [PMID: 15713428 DOI: 10.1016/j.ejphar.2004.12.034] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Accepted: 12/24/2004] [Indexed: 11/17/2022]
Abstract
ABT-594 ((R)-5-(2-azetidinylmethoxy)-2-chloropyridine) represents a novel class of broad-spectrum analgesics whose primary mechanism of action is activation of the neuronal nicotinic acetylcholine receptors. The present study characterized the effects of ABT-594 in a rat chemotherapy-induced neuropathic pain model, where it attenuated mechanical allodynia with an ED50 = 40 nmol/kg (i.p.). This anti-allodynic effect was not blocked by systemic (i.p.) pretreatment with naloxone but was blocked completely with mecamylamine. Pretreatment with chlorisondamine (0.2-5 micromol/kg, i.p.) only partially blocked the effects of ABT-594 at the higher doses tested. In contrast, central (i.c.v.) pretreatment with chlorisondamine completely blocked ABT-594's anti-allodynic effect. Taken together, the data demonstrate that ABT-594 has a potent anti-allodynic effect in the rat vincristine model and that, in addition to its strong central site of action, ABT-594's effects are partially mediated by peripheral nicotinic acetylcholine receptors in this animal model of chemotherapy-induced neuropathic pain.
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Affiliation(s)
- James J Lynch
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Department R4N5, Bldg. AP9A-LL, 100 Abbott Park Road, Abbott Park, IL 60064-6115, USA.
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30
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Dubé GR, Kohlhaas KL, Rueter LE, Surowy CS, Meyer MD, Briggs CA. Loss of functional neuronal nicotinic receptors in dorsal root ganglion neurons in a rat model of neuropathic pain. Neurosci Lett 2004; 376:29-34. [PMID: 15694269 DOI: 10.1016/j.neulet.2004.11.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 10/22/2004] [Accepted: 11/11/2004] [Indexed: 11/17/2022]
Abstract
Recent evidence has suggested that the anti-allodynic effect of neuronal acetylcholine receptor (nAChR) agonists may have a peripheral component [L.E. Rueter, K.L. Kohlhaas, P. Curzon, C.S. Surowy, M.D. Meyer, Peripheral and central sites of action for A-85380 in the spinal nerve ligation model of neuropathic pain, Pain 103 (2003) 269-276]. In further studies of the peripheral anti-allodynic mechanisms of nAChR agonists, we investigated the function of nAChRs in acutely isolated dorsal root ganglion (DRG) neurons from allodynic [L5-L6 spinal nerve ligation (SNL)] and naive adult rats. Following determination of cell diameter and membrane capacitance, responses to rapid applications of nAChR agonists were recorded under whole cell patch clamp. nAChR inward currents were observed in approximately 60% of naive neurons, across small, medium, and large diameter cells. Evoked nAChR currents could be clustered into three broad classes: fast transient, biphasic, and slow desensitizing currents, consistent with multiple subtypes of nAChR expressed in DRG [J.R. Genzen, W. Van Cleve, D.S. McGehee, Dorsal root ganglion neurons express multiple nicotinic acetylcholine receptor subtypes, J. Neurophysiol. 86 (2001) 1773-1782]. In contrast, in neurons from allodynic animals, the occurrence and amplitude of responses to nAChR agonists were significantly reduced. Reduced responsiveness to nAChR agonists covered the range of DRG neuron sizes. The decrease in the responsiveness to nAChR agonists was not seen in neighboring uninjured L4 neurons. The significant decrease in the number of cells with nAChR agonist responses, compounded with the significant decrease in response amplitude, indicates that there is a marked down regulation of functional nAChRs in DRG somata associated with SNL.
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Affiliation(s)
- Gilles R Dubé
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, AP9/1125, 100 Abbott Park Rd., Abbott Park, IL 60064-6118, USA.
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Rau KK, Johnson RD, Cooper BY. Nicotinic AChR in subclassified capsaicin-sensitive and -insensitive nociceptors of the rat DRG. J Neurophysiol 2004; 93:1358-71. [PMID: 15483069 DOI: 10.1152/jn.00591.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Nociceptive cells of the dorsal root ganglion (DRG) were subclassified, in vitro, according to patterns of voltage-activated currents. The distribution and form of nicotinic ACh receptors (nAChRs) were determined. nAChRs were present on both capsaicin-sensitive and -insensitive nociceptors but were not universally present in unmyelinated nociceptors. In contrast, all A delta nociceptors (types 4, 6, and 9) expressed slowly decaying nAChR. Three major forms of nicotinic currents were identified. Specific agonists and antagonists were used to demonstrate the presence of alpha7 in two classes of capsaicin-sensitive, unmyelinated nociceptors (types 2 and 8). In type 2 cells, alpha7-mediated currents were found in isolation. Whereas alpha7 was co-expressed with other nAChR in type 8 cells. These were the only classes in which alpha7 was identified. Other nociceptive classes expressed slowly decaying currents with beta4 pharmacology. Based on concentration response curves formed by nicotinic agonists [ACh, nicotine, dimethyl phenyl piperazinium (DMPP), cytisine] evidence emerged of two distinct nAChR differentially expressed in type 4 (alpha3beta4) and types 5 and 8 (alpha3beta4 alpha5). Although identification could not be made with absolute certainty, patterns of potency (type 4: DMPP > cytisine > nicotine = ACh; type 5 and type 8: DMPP = cytisine > nicotine = ACh) and efficacy provided strong support for the presence of two distinct channels based on an alpha3beta4 platform. Studies conducted on one nonnociceptive class (type 3) failed to reveal any nAChR. After multiple injections of Di-I (1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) into the hairy skin of the hindlimb, we identified cell types 2, 4, 6, 8, and 9 as skin nociceptors that expressed nicotinic receptors. We conclude that at least three nicotinic AChR are diversely distributed into discrete subclasses of nociceptors that innervate hairy skin.
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Affiliation(s)
- K K Rau
- Deptartment of Neuroscience, College of Medicine and University of Florida McKnight Brain Institute, Gainesville, FL 32610, USA
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32
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33
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Haberberger RV, Bernardini N, Kress M, Hartmann P, Lips KS, Kummer W. Nicotinic acetylcholine receptor subtypes in nociceptive dorsal root ganglion neurons of the adult rat. Auton Neurosci 2004; 113:32-42. [PMID: 15296793 DOI: 10.1016/j.autneu.2004.05.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Revised: 05/03/2004] [Accepted: 05/13/2004] [Indexed: 10/26/2022]
Abstract
Stimulation of nicotinic acetylcholine receptors (nAChR) excites peripheral sensory nerve fibres, but also exert antinociceptive effects. The differences in these nAChR-mediated effects could be related to the expression of different nAChR subtypes located on nociceptive neurons. In the present study, we focused on the recently described alpha 10-nAChR subunit, and on alpha 4 and alpha 7 subunits, which are the most abundant subunits in the central nervous system. In nociceptive neurons from thoracic and lumbar dorsal root ganglia (DRG), nAChR subunits were found at transcriptional (RT-PCR), translational (immunohistochemistry) and functional levels. Cultured DRG neurons express mRNA for the subunits alpha 2-7 and alpha 10. The alpha-subunit proteins 4, 7 and 10 were colocalised in virtually all nociceptive neurons that were identified by immunoreactivity for the vanilloid receptor TRPV-1. These findings were corroborated by current recordings and calcium measurements, which revealed excitatory inward currents and calcium responses in capsaicin sensitive neurons.
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Affiliation(s)
- Rainer Viktor Haberberger
- Institute for Anatomy and Cell Biology Justus Liebig University, Aulweg 123, D-35385 Giessen, Germany.
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Lang PM, Burgstahler R, Sippel W, Irnich D, Schlotter-Weigel B, Grafe P. Characterization of neuronal nicotinic acetylcholine receptors in the membrane of unmyelinated human C-fiber axons by in vitro studies. J Neurophysiol 2003; 90:3295-303. [PMID: 12878715 DOI: 10.1152/jn.00512.2003] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Application of acetylcholine to peripheral nerve terminals in the skin is a widely used test in studies of human small-fiber functions. However, a detailed pharmacological profile and the subunit composition of nicotinic acetylcholine receptors in human C-fiber axons are not known. In the present study, we recorded acetylcholine-induced changes of the excitability and of the intracellular Ca2+ concentration in C-fiber axons of isolated human nerve segments. In addition, using immunohistochemistry, an antibody of a subtype of nicotinic acetylcholine receptor was tested. Acetylcholine and agonists reduced the current necessary for the generation of action potentials in C fibers by <or=30%. This increase in axonal excitability was accompanied by a rise in the free intracellular Ca2+ concentration. The following rank order of potency for agonists was found: epibatidine >> 5-Iodo-A-85380 > 1,1-dimethyl-4-phenylpiperazinium iodide > nicotine > cytisine > acetylcholine; choline had no effect. The epibatidine-induced increase in axonal excitability was blocked by mecamylamine and, less efficiently, by methyllycacontine and dihydro-beta-erythroidine. Many C-fiber axons were labeled by an antibody that recognizes the alpha5 subunit of nicotinic acetylcholine receptors. In summary, electrophysiological and immunohistochemical data indicate the functional expression of nicotinic acetylcholine receptors composed of alpha3, alpha5, and beta4 but not of alpha4/beta2 or of alpha7 subunits in the axonal membrane of unmyelinated human C fibers. In addition, the observations suggest that the axonal membrane of C fibers in isolated segments of human sural nerve can be used as a model for presumed cholinergic chemosensitivity of axonal terminals.
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Affiliation(s)
- P M Lang
- Departments of Physiology and Anesthesiology and Friedrich-Baur-Institute, Ludwig-Maximilians University, 80336 Munich, Germany
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