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Braunscheidel KM, Voren G, Fowler CD, Lu Q, Kuryatov A, Cameron MD, Ibañez-Tallon I, Lindstrom JM, Kamenecka TM, Kenny PJ. SR9883 is a novel small-molecule enhancer of α4β2* nicotinic acetylcholine receptor signaling that decreases intravenous nicotine self-administration in rats. Front Mol Neurosci 2024; 17:1459098. [PMID: 39346680 PMCID: PMC11428108 DOI: 10.3389/fnmol.2024.1459098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 08/16/2024] [Indexed: 10/01/2024] Open
Abstract
Background Most smokers attempting to quit will quickly relapse to tobacco use even when treated with the most efficacious smoking cessation agents currently available. This highlights the need to develop effective new smoking cessation medications. Evidence suggests that positive allosteric modulators (PAM) and other enhancers of nicotinic acetylcholine receptor (nAChR) signaling could have therapeutic utility as smoking cessation agents. Methods 3-[3-(3-pyridyl)-1,2,4-oxadiazol-5-yl]benzonitrile (NS9283) was used as a starting point for medical chemistry efforts to develop novel small molecule enhancers of α4β2* nAChR stoichiometries containing a low-affinity agonist binding site at the interface of α4/α4 and α4/α5 subunits. Results The NS9283 derivative SR9883 enhanced the effect of nicotine on α4β2* nAChR stoichiometries containing low-affinity agonist binding sites, with EC50 values from 0.2-0.4 μM. SR9883 had no effect on α3β2* or α3β4* nAChRs. SR9883 was bioavailable after intravenous (1 mg kg-1) and oral (10-20 mg kg-1) administration and penetrated into the brain. When administered alone, SR9883 (5-10 mg kg-1) had no effect on locomotor activity or intracranial self-stimulation (ICSS) thresholds in mice. When co-administered with nicotine, SR9883 enhanced locomotor suppression and elevations of ICSS thresholds induced by nicotine. SR9883 (5 and 10 mg kg-1) decreased responding for intravenous nicotine infusions (0.03 mg kg-1 per infusion) but had no effect on responding for food rewards in rats. Conclusions These data suggest that SR9883 is useful for investigating behavioral processes regulated by certain α4β2* nAChR stoichiometries. SR9883 and related compounds with favorable drug-like physiochemical and pharmacological properties hold promise as novel treatments of tobacco use disorder.
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Affiliation(s)
- Kevin M. Braunscheidel
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - George Voren
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Christie D. Fowler
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, United States
| | - Qun Lu
- The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States
| | - Alexander Kuryatov
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Michael D. Cameron
- The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States
| | - Ines Ibañez-Tallon
- The Laboratory of Molecular Biology, The Rockefeller University, New York, NY, United States
| | - Jon M. Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States
| | - Theodore M. Kamenecka
- The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL, United States
| | - Paul J. Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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Herman RJ, Hayes MR, Audrain-McGovern J, Ashare RL, Schmidt HD. Liraglutide attenuates nicotine self-administration as well as nicotine seeking and hyperphagia during withdrawal in male and female rats. Psychopharmacology (Berl) 2023; 240:1373-1386. [PMID: 37129617 PMCID: PMC11088902 DOI: 10.1007/s00213-023-06376-w] [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] [Received: 01/11/2023] [Accepted: 04/26/2023] [Indexed: 05/03/2023]
Abstract
RATIONALE Nicotine cessation is associated with increased consumption of highly palatable foods and body weight gain in most smokers. Concerns about body weight gain are a major barrier to maintaining long-term smoking abstinence, and current treatments for nicotine use disorder (NUD) delay, but do not prevent, body weight gain during abstinence. Glucagon-like peptide-1 receptor (GLP-1R) agonists reduce food intake and are FDA-approved for treating obesity. However, the effects of GLP-1R agonist monotherapy on nicotine seeking and withdrawal-induced hyperphagia are unknown. OBJECTIVES We screened the efficacy of the long-lasting GLP-1R agonist liraglutide to reduce nicotine-mediated behaviors including voluntary nicotine taking, as well as nicotine seeking and hyperphagia during withdrawal. METHODS Male and female rats self-administered intravenous nicotine (0.03 mg/kg/inf) for ~21 days. Daily liraglutide administration (25 μg/kg, i.p.) started on the last self-administration day and continued throughout the extinction and reinstatement phases of the experiment. Once nicotine taking was extinguished, the reinstatement of nicotine-seeking behavior was assessed after an acute priming injection of nicotine (0.2 mg/kg, s.c.) and re-exposure to conditioned light cues. Using a novel model of nicotine withdrawal-induced hyperphagia, intake of a high fat diet (HFD) was measured during home cage abstinence in male and female rats with a history of nicotine self-administration. RESULTS Liraglutide attenuated nicotine self-administration and reinstatement in male and female rats. Repeated liraglutide attenuated withdrawal-induced hyperphagia and body weight gain in male and female rats at a dose that was not associated with malaise-like effects. CONCLUSIONS These findings support further studies investigating the translational potential of GLP-1R agonists to treat NUD.
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Affiliation(s)
- R J Herman
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M R Hayes
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, TRL Room 2215, Philadelphia, PA, 19104, USA
| | - J Audrain-McGovern
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, TRL Room 2215, Philadelphia, PA, 19104, USA
| | - R L Ashare
- Department of Psychology, College of Arts and Sciences, University at Buffalo, SUNY, Buffalo, NY, USA
| | - H D Schmidt
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, TRL Room 2215, Philadelphia, PA, 19104, USA.
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, 125 South 31st Street, TRL Room 2215, Philadelphia, PA, 19104, USA.
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3
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Maurer JJ, Wimmer ME, Turner CA, Herman RJ, Zhang Y, Ragnini K, Ferrante J, Kimmey BA, Crist RC, Christopher Pierce R, Schmidt HD. Paternal nicotine taking elicits heritable sex-specific phenotypes that are mediated by hippocampal Satb2. Mol Psychiatry 2022; 27:3864-3874. [PMID: 35595980 PMCID: PMC9675874 DOI: 10.1038/s41380-022-01622-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/04/2022] [Accepted: 05/11/2022] [Indexed: 02/08/2023]
Abstract
Nicotine intake, whether through tobacco smoking or e-cigarettes, remains a global health concern. An emerging preclinical literature indicates that parental nicotine exposure produces behavioral, physiological, and molecular changes in subsequent generations. However, the heritable effects of voluntary parental nicotine taking are unknown. Here, we show increased acquisition of nicotine taking in male and female offspring of sires that self-administered nicotine. In contrast, self-administration of sucrose and cocaine were unaltered in male and female offspring suggesting that the intergenerational effects of paternal nicotine taking may be reinforcer specific. Further characterization revealed memory deficits and increased anxiety-like behaviors in drug-naive male, but not female, offspring of nicotine-experienced sires. Using an unbiased, genome-wide approach, we discovered that these phenotypes were associated with decreased expression of Satb2, a transcription factor known to play important roles in synaptic plasticity and memory formation, in the hippocampus of nicotine-sired male offspring. This effect was sex-specific as no changes in Satb2 expression were found in nicotine-sired female offspring. Finally, increasing Satb2 levels in the hippocampus prevented the escalation of nicotine intake and rescued the memory deficits associated with paternal nicotine taking in male offspring. Collectively, these findings indicate that paternal nicotine taking produces heritable sex-specific molecular changes that promote addiction-like phenotypes and memory impairments in male offspring.
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Affiliation(s)
- John J Maurer
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Mathieu E Wimmer
- Department of Psychology, College of Liberal Arts, Temple University, Philadelphia, PA, 19122, USA
| | - Christopher A Turner
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Rae J Herman
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Yafang Zhang
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Kael Ragnini
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Julia Ferrante
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Blake A Kimmey
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Richard C Crist
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - R Christopher Pierce
- Brain Health Institute and Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, 08854, USA
| | - Heath D Schmidt
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Appiani R, Pallavicini M, Hamouda AK, Bolchi C. Pyrrolidinyl benzofurans and benzodioxanes: Selective α4β2 nicotinic acetylcholine receptor ligands with different activity profiles at the two receptor stoichiometries. Bioorg Med Chem Lett 2022; 65:128701. [PMID: 35346843 DOI: 10.1016/j.bmcl.2022.128701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/17/2022] [Accepted: 03/23/2022] [Indexed: 11/28/2022]
Abstract
A series of racemic benzofurans bearing N-methyl-2-pyrrolidinyl residue at C(2) or C(3) has been synthesized and tested for affinity at the α4β2 and α3β4 nicotine acetylcholine receptors (nAChRs). As previously reported for the benzodioxane based analogues, hydroxylation at proper position of benzene ring results in high α4β2 nAChR affinity and α4β2 vs. α3β4 nAChR selectivity. 7-Hydroxy-N-methyl-2-pyrrolidinyl-1,4-benzodioxane (2) and its 7- and 5-amino benzodioxane analogues 3 and 4, which are all α4β2 nAChR partial agonists, and 2-(N-methyl-2-pyrrolidinyl)-6-hydroxybenzofuran (12) were selected for functional characterization at the two α4β2 stoichiometries, the high sensitivity (α4)2(β2)3 and the low sensitivity (α4)3(β2)2. The benzene pattern substitution, which had previously been found to control α4β2 partial agonist activity and α4β2 vs. α3β4 selectivity, proved to be also involved in stoichiometry-selectivity. The 7-hydroxybenzodioxane derivative 2 selectively activates (α4)2(β2)3 nAChR, which cannot be activated by its 5-amino analogue 4. A marginal structural modification, not altering the base pyrrolidinyl benzodioxane scaffold, resulted in opposite activity profiles at the two α4β2 nAChR isoforms providing an interesting novel case study.
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Affiliation(s)
- Rebecca Appiani
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy.
| | - Marco Pallavicini
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy.
| | - Ayman K Hamouda
- Department of Pharmaceutical Sciences and Health Outcomes, Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, TX, USA.
| | - Cristiano Bolchi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, via Mangiagalli 25, I-20133 Milano, Italy.
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Wills L, Ables JL, Braunscheidel KM, Caligiuri SPB, Elayouby KS, Fillinger C, Ishikawa M, Moen JK, Kenny PJ. Neurobiological Mechanisms of Nicotine Reward and Aversion. Pharmacol Rev 2022; 74:271-310. [PMID: 35017179 PMCID: PMC11060337 DOI: 10.1124/pharmrev.121.000299] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 08/24/2021] [Indexed: 12/27/2022] Open
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) regulate the rewarding actions of nicotine contained in tobacco that establish and maintain the smoking habit. nAChRs also regulate the aversive properties of nicotine, sensitivity to which decreases tobacco use and protects against tobacco use disorder. These opposing behavioral actions of nicotine reflect nAChR expression in brain reward and aversion circuits. nAChRs containing α4 and β2 subunits are responsible for the high-affinity nicotine binding sites in the brain and are densely expressed by reward-relevant neurons, most notably dopaminergic, GABAergic, and glutamatergic neurons in the ventral tegmental area. High-affinity nAChRs can incorporate additional subunits, including β3, α6, or α5 subunits, with the resulting nAChR subtypes playing discrete and dissociable roles in the stimulatory actions of nicotine on brain dopamine transmission. nAChRs in brain dopamine circuits also participate in aversive reactions to nicotine and the negative affective state experienced during nicotine withdrawal. nAChRs containing α3 and β4 subunits are responsible for the low-affinity nicotine binding sites in the brain and are enriched in brain sites involved in aversion, including the medial habenula, interpeduncular nucleus, and nucleus of the solitary tract, brain sites in which α5 nAChR subunits are also expressed. These aversion-related brain sites regulate nicotine avoidance behaviors, and genetic variation that modifies the function of nAChRs in these sites increases vulnerability to tobacco dependence and smoking-related diseases. Here, we review the molecular, cellular, and circuit-level mechanisms through which nicotine elicits reward and aversion and the adaptations in these processes that drive the development of nicotine dependence. SIGNIFICANCE STATEMENT: Tobacco use disorder in the form of habitual cigarette smoking or regular use of other tobacco-related products is a major cause of death and disease worldwide. This article reviews the actions of nicotine in the brain that contribute to tobacco use disorder.
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Affiliation(s)
- Lauren Wills
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Jessica L Ables
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Kevin M Braunscheidel
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Stephanie P B Caligiuri
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Karim S Elayouby
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Clementine Fillinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Masago Ishikawa
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Janna K Moen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
| | - Paul J Kenny
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York
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6
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Bavo F, Pallavicini M, Gotti C, Appiani R, Moretti M, Colombo SF, Pucci S, Viani P, Budriesi R, Renzi M, Fucile S, Bolchi C. Modifications at C(5) of 2-(2-Pyrrolidinyl)-Substituted 1,4-Benzodioxane Elicit Potent α4β2 Nicotinic Acetylcholine Receptor Partial Agonism with High Selectivity over the α3β4 Subtype. J Med Chem 2020; 63:15668-15692. [PMID: 33325696 DOI: 10.1021/acs.jmedchem.0c01150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of diastereomeric 2-(2-pyrrolidinyl)-1,4-benzodioxanes bearing a small, hydrogen-bonding substituent at the 7-, 6-, or 5-position of benzodioxane have been studied for α4β2 and α3β4 nicotinic acetylcholine receptor affinity and activity. Analogous to C(5)H replacement with N and to a much greater extent than decoration at C(7), substitution at benzodioxane C(5) confers very high α4β2/α3β4 selectivity to the α4β2 partial agonism. Docking into the two receptor structures recently determined by cryo-electron microscopy and site-directed mutagenesis at the minus β2 side converge in indicating that the limited accommodation capacity of the β2 pocket, compared to that of the β4 pocket, makes substitution at C(5) rather than at more projecting C(7) position determinant for this pursued subtype selectivity.
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Affiliation(s)
- Francesco Bavo
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, I-20133 Milano, Italy
| | - Marco Pallavicini
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, I-20133 Milano, Italy
| | - Cecilia Gotti
- Institute of Neuroscience, CNR, Via Vanvitelli 32, I-20129 Milano, Italy
| | - Rebecca Appiani
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, I-20133 Milano, Italy
| | - Milena Moretti
- Institute of Neuroscience, CNR, Via Vanvitelli 32, I-20129 Milano, Italy.,Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Via Vanvitelli 32, I-20129 Milano, Italy
| | | | - Susanna Pucci
- Institute of Neuroscience, CNR, Via Vanvitelli 32, I-20129 Milano, Italy.,Hunimed University, Via Rita Levi-Montalcini 4, Pieve Emanuele, I-20090 Milan, Italy
| | - Paola Viani
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Via Vanvitelli 32, I-20129 Milano, Italy
| | - Roberta Budriesi
- Dipartimento di Farmacia e Biotecnologie, Università degli Studi di Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
| | - Massimiliano Renzi
- Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma, Piazzale Moro 5, 00185 Roma, Italy
| | - Sergio Fucile
- Dipartimento di Fisiologia e Farmacologia, Sapienza Università di Roma, Piazzale Moro 5, 00185 Roma, Italy.,I.R.C.C.S. Neuromed, Via Atinese 18, 86077 Pozzilli, Italy
| | - Cristiano Bolchi
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Milano, Via Mangiagalli 25, I-20133 Milano, Italy
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7
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Moerke MJ, McMahon LR, Wilkerson JL. More than Smoke and Patches: The Quest for Pharmacotherapies to Treat Tobacco Use Disorder. Pharmacol Rev 2020; 72:527-557. [PMID: 32205338 DOI: 10.1124/pr.119.018028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Tobacco use is a persistent public health issue. It kills up to half its users and is the cause of nearly 90% of all lung cancers. The main psychoactive component of tobacco is nicotine, primarily responsible for its abuse-related effects. Accordingly, most pharmacotherapies for smoking cessation target nicotinic acetylcholine receptors (nAChRs), nicotine's major site of action in the brain. The goal of the current review is twofold: first, to provide a brief overview of the most commonly used behavioral procedures for evaluating smoking cessation pharmacotherapies and an introduction to pharmacokinetic and pharmacodynamic properties of nicotine important for consideration in the development of new pharmacotherapies; and second, to discuss current and potential future pharmacological interventions aimed at decreasing tobacco use. Attention will focus on the potential for allosteric modulators of nAChRs to offer an improvement over currently approved pharmacotherapies. Additionally, given increasing public concern for the potential health consequences of using electronic nicotine delivery systems, which allow users to inhale aerosolized solutions as an alternative to smoking tobacco, an effort will be made throughout this review to address the implications of this relatively new form of nicotine delivery, specifically as it relates to smoking cessation. SIGNIFICANCE STATEMENT: Despite decades of research that have vastly improved our understanding of nicotine and its effects on the body, only a handful of pharmacotherapies have been successfully developed for use in smoking cessation. Thus, investigation of alternative pharmacological strategies for treating tobacco use disorder remains active; allosteric modulators of nicotinic acetylcholine receptors represent one class of compounds currently under development for this purpose.
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Affiliation(s)
- M J Moerke
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
| | - L R McMahon
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
| | - J L Wilkerson
- Division of Preclinical Pharmacology, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (M.J.M.) and Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, Florida (L.R.M., J.L.W.)
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8
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Houchat JN, Cartereau A, Le Mauff A, Taillebois E, Thany SH. An Overview on the Effect of Neonicotinoid Insecticides on Mammalian Cholinergic Functions through the Activation of Neuronal Nicotinic Acetylcholine Receptors. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17093222. [PMID: 32384754 PMCID: PMC7246883 DOI: 10.3390/ijerph17093222] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/27/2020] [Accepted: 04/30/2020] [Indexed: 01/04/2023]
Abstract
Neonicotinoid insecticides are used worldwide and have been demonstrated as toxic to beneficial insects such as honeybees. Their effectiveness is predominantly attributed to their high affinity for insect neuronal nicotinic acetylcholine receptors (nAChRs). Mammalian neuronal nAChRs are of major importance because cholinergic synaptic transmission plays a key role in rapid neurotransmission, learning and memory processes, and neurodegenerative diseases. Because of the low agonist effects of neonicotinoid insecticides on mammalian neuronal nAChRs, it has been suggested that they are relatively safe for mammals, including humans. However, several lines of evidence have demonstrated that neonicotinoid insecticides can modulate cholinergic functions through neuronal nAChRs. Major studies on the influence of neonicotinoid insecticides on cholinergic functions have been conducted using nicotine low-affinity homomeric α7 and high-affinity heteromeric α4β2 receptors, as they are the most abundant in the nervous system. It has been found that the neonicotinoids thiamethoxam and clothianidin can activate the release of dopamine in rat striatum. In some contexts, such as neurodegenerative diseases, they can disturb the neuronal distribution or induce oxidative stress, leading to neurotoxicity. This review highlights recent studies on the mode of action of neonicotinoid insecticides on mammalian neuronal nAChRs and cholinergic functions.
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9
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Wilkerson JL, Deba F, Crowley ML, Hamouda AK, McMahon LR. Advances in the In vitro and In vivo pharmacology of Alpha4beta2 nicotinic receptor positive allosteric modulators. Neuropharmacology 2020; 168:108008. [PMID: 32113032 DOI: 10.1016/j.neuropharm.2020.108008] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 02/08/2020] [Accepted: 02/11/2020] [Indexed: 11/29/2022]
Abstract
Receptors containing α4 and β2 subunits are a major neuronal nicotinic acetylcholine receptor (nAChR) subtype in the brain. This receptor plays a critical role in nicotine addiction, with potential smoking cessation therapeutics producing modulation of α4β2 nAChR. In addition, compounds that act as agonists at α4β2 nAChR may be useful for the treatment of pathological pain. Further, as the α4β2 nAChR has been implicated in cognition, therapeutics that act as α4β2 nAChR agonists are also being examined as treatments for cognitive disorders and neurological diseases that impact cognitive function, such as Alzheimer's disease and schizophrenia. This review will cover the molecular in vitro evidence that allosteric modulators of the α4β2 neuronal nAChR provide several advantages over traditional α4β2 nAChR orthosteric ligands. Specifically, we explore the concept that nAChR allosteric modulators allow for greater pharmacological selectivity, while minimizing potential deleterious off-target effects. Further, here we discuss the development and preclinical in vivo behavioral assessment of allosteric modulators at the α4β2 neuronal nAChR as therapeutics for smoking cessation, pathological pain, as well as cognitive disorders and neurological diseases that impact cognitive function. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
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Affiliation(s)
- Jenny L Wilkerson
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, 32610, United States.
| | - Farah Deba
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Texas at Tyler, Tyler, TX, 75799, United States
| | - Morgan L Crowley
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL, 32610, United States
| | - Ayman K Hamouda
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Texas at Tyler, Tyler, TX, 75799, United States.
| | - Lance R McMahon
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, 32610, United States.
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10
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Laikowski MM, Reisdorfer F, Moura S. NAChR α4β2 Subtype and their Relation with Nicotine Addiction, Cognition, Depression and Hyperactivity Disorder. Curr Med Chem 2019; 26:3792-3811. [PMID: 29637850 DOI: 10.2174/0929867325666180410105135] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/27/2017] [Accepted: 04/05/2018] [Indexed: 01/07/2023]
Abstract
BACKGROUND Neuronal α4β2 nAChRs are receptors involved in the role of neurotransmitters regulation and release, and this ionic channel participates in biological process of memory, learning and attention. This work aims to review the structure and functioning of the α4β2 nAChR emphasizing its role in the treatment of associated diseases like nicotine addiction and underlying pathologies such as cognition, depression and attention-deficit hyperactivity disorder. METHODS The authors realized extensive bibliographic research using the descriptors "Nicotine Receptor α4β2" and "cognition", "depression", "attention-deficit hyperactivity disorder", besides cross-references of the selected articles and after analysis of references in the specific literature. RESULTS As results, it was that found 179 relevant articles presenting the main molecules with affinity to nAChR α4β2 related to the cited diseases. The α4β2 nAChR subtype is a remarkable therapeutic target since this is the most abundant receptor in the central nervous system. CONCLUSION In summary, this review presents perspectives on the pharmacology and therapeutic targeting of α4β2 nAChRs for the treatment of cognition and diseases like nicotine dependence, depression and attention-deficit hyperactivity disorder.
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Affiliation(s)
- Manuela M Laikowski
- Laboratory of Natural and Synthetics Products, University of Caxias do Sul, Caxias do Sul, Brazil
| | - Fávero Reisdorfer
- Laboratory of Drug Development and Quality Control, University Federal of Pampa, Brazil
| | - Sidnei Moura
- Laboratory of Natural and Synthetics Products, University of Caxias do Sul, Caxias do Sul, Brazil
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11
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Mazzaferro S, Bermudez I, Sine SM. Potentiation of a neuronal nicotinic receptor via pseudo-agonist site. Cell Mol Life Sci 2019; 76:1151-1167. [PMID: 30600358 PMCID: PMC8022356 DOI: 10.1007/s00018-018-2993-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 11/28/2018] [Accepted: 12/10/2018] [Indexed: 11/26/2022]
Abstract
Neuronal nicotinic receptors containing α4 and β2 subunits assemble in two pentameric stoichiometries, (α4)3(β2)2 and (α4)2(β2)3, each with distinct pharmacological signatures; (α4)3(β2)2 receptors are strongly potentiated by the drug NS9283, whereas (α4)2(β2)3 receptors are unaffected. Despite this stoichiometry-selective pharmacology, the molecular identity of the target for NS9283 remains elusive. Here, studying (α4)3(β2)2 receptors, we show that mutations at either the principal face of the β2 subunit or the complementary face of the α4 subunit prevent NS9283 potentiation of ACh-elicited single-channel currents, suggesting the drug targets the β2-α4 pseudo-agonist sites, the α4-α4 agonist site, or both sites. To distinguish among these possibilities, we generated concatemeric receptors with mutations at specified subunit interfaces, and monitored the ability of NS9283 to potentiate ACh-elicited single-channel currents. We find that a mutation at the principal face of the β2 subunit at either β2-α4 pseudo-agonist site suppresses potentiation, whereas mutation at the complementary face of the α4 subunit at the α4-α4 agonist site allows a significant potentiation. Thus, monitoring potentiation of single concatemeric receptor channels reveals that the β2-α4 pseudo-agonist sites are required for stoichiometry-selective drug action. Together with the recently determined structure of the (α4)3(β2)2 receptor, the findings have implications for structure-guided drug design.
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Affiliation(s)
- Simone Mazzaferro
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA
| | - Isabel Bermudez
- School of Life Sciences, Oxford Brookes University, Oxford, OX3 OBP, UK
| | - Steven M Sine
- Receptor Biology Laboratory, Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA.
- Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA.
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN, 55905, USA.
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12
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Schmidt HD, Rupprecht LE, Addy NA. Neurobiological and Neurophysiological Mechanisms Underlying Nicotine Seeking and Smoking Relapse. MOLECULAR NEUROPSYCHIATRY 2019; 4:169-189. [PMID: 30815453 PMCID: PMC6388439 DOI: 10.1159/000494799] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/23/2018] [Indexed: 12/19/2022]
Abstract
Tobacco-related morbidity and mortality continue to be a significant public health concern. Unfortunately, current FDA-approved smoking cessation pharmacotherapies have limited efficacy and are associated with high rates of relapse. Therefore, a better understanding of the neurobiological and neurophysiological mechanisms that promote smoking relapse is needed to develop novel smoking cessation medications. Here, we review preclinical studies focused on identifying the neurotransmitter and neuromodulator systems that mediate nicotine relapse, often modeled in laboratory animals using the reinstatement paradigm, as well as the plasticity-dependent neurophysiological mechanisms that facilitate nicotine reinstatement. Particular emphasis is placed on how these neuroadaptations relate to smoking relapse in humans. We also highlight a number of important gaps in our understanding of the neural mechanisms underlying nicotine reinstatement and critical future directions, which may lead toward the development of novel, target pharmacotherapies for smoking cessation.
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Affiliation(s)
- Heath D. Schmidt
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Laura E. Rupprecht
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut, USA
| | - Nii A. Addy
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut, USA
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
- Interdepartmental Neuroscience Program, Yale Graduate School of Arts and Sciences, New Haven, Connecticut, USA
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13
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MacLean RR, Waters AJ, Brede E, Sofuoglu M. Effects of galantamine on smoking behavior and cognitive performance in treatment-seeking smokers prior to a quit attempt. Hum Psychopharmacol 2018; 33:e2665. [PMID: 29926988 PMCID: PMC6168949 DOI: 10.1002/hup.2665] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/27/2018] [Accepted: 05/18/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Drugs that enhance cholinergic transmission have demonstrated promise treating addictive disorders. Galantamine, an acetylcholinesterase inhibitor, may reduce cigarette smoking in otherwise healthy treatment-seeking smokers. METHODS The current study is a double-blind, placebo-controlled, study that randomized daily smokers (n = 60) to receive one of two doses of galantamine extended release (8 or 16 mg/day), or a placebo treatment. Participants completed a smoking choice task as well as study measures and cognitive tasks in the laboratory and daily life using ecological momentary assessment. Analysis focused on smoking behavior and satisfaction, cognitive performance, and decision to smoke prior to a quit attempt. RESULTS Linear mixed models demonstrated that, compared with placebo, both doses of galantamine reduced smoking in a laboratory choice task (p = 0.006) and decreased urine cotinine levels, but not self-reported cigarettes, during the pre-quit period (p = 0.007). Treatment had minimal effect on smoking satisfaction or cognitive performance. CONCLUSIONS The results suggest that galantamine reduces nicotine intake but it is unlikely that galantamine improves cognitive performance in otherwise healthy, treatment-seeking smokers. Larger randomized clinical trials can determine if galantamine adjunctive to addiction treatment can improve smoking treatment outcomes.
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Affiliation(s)
- Robert Ross MacLean
- VA Connecticut Healthcare System, West Haven, Connecticut,Yale University School of Medicine, New Haven, Connecticut
| | - Andrew J. Waters
- Uniformed Services University of Health Sciences, Bethesda, Maryland
| | - Emily Brede
- National Institute of Health, Bethesda, Maryland
| | - Mehmet Sofuoglu
- VA Connecticut Healthcare System, West Haven, Connecticut,Yale University School of Medicine, New Haven, Connecticut
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14
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Designing selective modulators for the nicotinic receptor subtypes: challenges and opportunities. Future Med Chem 2018; 10:433-459. [PMID: 29451400 DOI: 10.4155/fmc-2017-0169] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nicotinic receptors are membrane proteins involved in several physiological processes. They are considered suitable drug targets for various CNS disorders or conditions, as shown by the large number of compounds which have entered clinical trials. In recent years, nonconventional agonists have been discovered: positive allosteric modulators, allosteric agonists, site-specific agonists and silent desensitizers are compounds able to modulate the receptor interacting at sites different from the orthodox one, or to desensitize the receptor without prior opening. While these new findings can further complicate the pharmacology of these proteins and the design and optimization of ligands, they undoubtedly offer new opportunities to find drugs for the many therapeutic indications involving nicotinic receptors.
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15
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Bagdas D, Ergun D, Jackson A, Toma W, Schulte M, Damaj M. Allosteric modulation of α4β2* nicotinic acetylcholine receptors: Desformylflustrabromine potentiates antiallodynic response of nicotine in a mouse model of neuropathic pain. Eur J Pain 2018; 22:84-93. [PMID: 28809075 PMCID: PMC9829446 DOI: 10.1002/ejp.1092] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2017] [Indexed: 01/12/2023]
Abstract
BACKGROUND Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels. The α4β2 subtype of nAChRs plays an important role in the mediation of pain and several nicotine-evoked responses. Agonists and partial agonists of α4β2 nAChRs show efficacy in animal pain models. In addition, the antinociceptive properties of nicotine, a non-selective nAChR agonist with a high affinity for α4β2 nAChRs, is well-known. There is a growing body of evidence pointing to allosteric modulation of nAChRs as an alternative treatment strategy in experimental pain. Desformylflustrabromine (dFBr) is a positive allosteric modulator (PAM) at α4β2 nAChRs that enhances agonist responses without activating receptors. We hypothesized that dFBr may enhance nicotine-induced antinociception. METHODS The present study investigated whether dFBr could attenuate mouse chronic constriction injury (CCI)-induced neuropathic pain by increasing endogenous cholinergic tone or potentiating the nicotine-evoked antiallodynic response. RESULTS We found that subcutaneous administration of dFBr failed to reduce pain behaviour on its own. However, the combination of dFBr with nicotine significantly reversed neuropathic pain behaviour dose- and time-dependently without motor impairment. Our data revealed that this effect was mediated by the α4β2 nAChRs by using competitive α4β2 antagonist dihydro-β-erythroidine. In addition, dFBr failed to potentiate the antiallodynic effect of morphine, which shows the effect of dFBr is unique to α4β2 nAChRs. CONCLUSIONS The present results suggest that allosteric modulation of α4β2 nAChR may provide new strategies in chronic neuropathic pain. SIGNIFICANCE α4β2 nAChRs are involved in pain modulation. dFBr, a PAM at α4β2 nAChRs, potentiates the nicotine response dose-dependently in neuropathic pain. Thus, the present results suggest that allosteric modulation of α4β2* nAChR may provide new strategies in chronic neuropathic pain.
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Affiliation(s)
- D. Bagdas
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 USA,Experimental Animals Breeding and Research Center, Faculty of Medicine, Uludag University, Bursa 16059, Turkey
| | - D. Ergun
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 USA
| | - A. Jackson
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 USA
| | - W. Toma
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 USA
| | - M.K. Schulte
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences, Philadelphia, PA, USA
| | - M.I. Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298-0613 USA
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16
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Wu J, Cippitelli A, Zhang Y, Debevec G, Schoch J, Ozawa A, Yu Y, Liu H, Chen W, Houghten RA, Welmaker GS, Giulianotti MA, Toll L. Highly Selective and Potent α4β2 nAChR Antagonist Inhibits Nicotine Self-Administration and Reinstatement in Rats. J Med Chem 2017; 60:10092-10104. [PMID: 29178785 DOI: 10.1021/acs.jmedchem.7b01250] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The α4β2 nAChR is the most predominant subtype in the brain and is a well-known culprit for nicotine addiction. Previously we presented a series of α4β2 nAChR selective compounds that were discovered from a mixture-based positional-scanning combinatorial library. Here we report further optimization identified highly potent and selective α4β2 nAChR antagonists 5 (AP-202) and 13 (AP-211). Both compounds are devoid of in vitro agonist activity and are potent inhibitors of epibatidine-induced changes in membrane potential in cells containing α4β2 nAChR, with IC50 values of approximately 10 nM, but are weak agonists in cells containing α3β4 nAChR. In vivo studies show that 5 can significantly reduce operant nicotine self-administration and nicotine relapse-like behavior in rats at doses of 0.3 and 1 mg/kg. The pharmacokinetic data also indicate that 5, via sc administration, is rapidly absorbed into the blood, reaching maximal concentration within 10 min with a half-life of less than 1 h.
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Affiliation(s)
- Jinhua Wu
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Assuage Pharmaceuticals, Inc , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Andrea Cippitelli
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Yaohong Zhang
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, P. R. China.,School of Chemistry and Chemical Engineering, Zhejiang Key Laboratory of Alternative Technologies for Fine Chemicals Process, Shaoxing University , Shaoxing 312000, Zhejiang, P. R. China
| | - Ginamarie Debevec
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Jennifer Schoch
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Akihiko Ozawa
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Yongping Yu
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, P. R. China
| | - Huan Liu
- Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, P. R. China
| | - Wenteng Chen
- Institute of Materia Medica, College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, P. R. China
| | - Richard A Houghten
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Assuage Pharmaceuticals, Inc , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Gregory S Welmaker
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Assuage Pharmaceuticals, Inc , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Marc A Giulianotti
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Assuage Pharmaceuticals, Inc , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Lawrence Toll
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States.,Assuage Pharmaceuticals, Inc , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
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17
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Wang J, Lindstrom J. Orthosteric and allosteric potentiation of heteromeric neuronal nicotinic acetylcholine receptors. Br J Pharmacol 2017; 175:1805-1821. [PMID: 28199738 DOI: 10.1111/bph.13745] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/30/2017] [Accepted: 02/06/2017] [Indexed: 12/16/2022] Open
Abstract
Heteromeric nicotinic ACh receptors (nAChRs) were thought to have two orthodox agonist-binding sites at two α/β subunit interfaces. Highly selective ligands are hard to develop by targeting orthodox agonist sites because of high sequence similarity of this binding pocket among different subunits. Recently, unorthodox ACh-binding sites have been discovered at some α/α and β/α subunit interfaces, such as α4/α4, α5/α4 and β3/α4. Targeting unorthodox sites may yield subtype-selective ligands, such as those for (α4β2)2 α5, (α4β2)2 β3 and (α6β2)2 β3 nAChRs. The unorthodox sites have unique pharmacology. Agonist binding at one unorthodox site is not sufficient to activate nAChRs, but it increases activation from the orthodox sites. NS9283, a selective agonist for the unorthodox α4/α4 site, was initially thought to be a positive allosteric modulator (PAM). NS9283 activates nAChRs with three engineered α4/α4 sites. PAMs, on the other hand, act at allosteric sites where ACh cannot bind. Known PAM sites include the ACh-homologous non-canonical site (e.g. morantel at β/α), the C-terminus (e.g. Br-PBTC and 17β-estradiol), a transmembrane domain (e.g. LY2087101) or extracellular and transmembrane domain interfaces (e.g. NS206). Some of these PAMs, such as Br-PBTC and 17β-estradiol, require only one subunit to potentiate activation of nAChRs. In this review, we will discuss differences between activation from orthosteric and allosteric sites, their selective ligands and clinical implications. These studies have advanced understanding of the structure, assembly and pharmacology of heteromeric neuronal nAChRs. LINKED ARTICLES This article is part of a themed section on Nicotinic Acetylcholine Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.11/issuetoc.
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Affiliation(s)
- Jingyi Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Jon Lindstrom
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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