1
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Akinola LS, Gonzales J, Buzzi B, Mathews HL, Papke RL, Stitzel JA, Damaj MI. Investigating the role of nicotinic acetylcholine receptors in menthol's effects in mice. Drug Alcohol Depend 2024; 257:111262. [PMID: 38492255 PMCID: PMC11031278 DOI: 10.1016/j.drugalcdep.2024.111262] [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: 09/08/2023] [Revised: 02/13/2024] [Accepted: 03/01/2024] [Indexed: 03/18/2024]
Abstract
The use of menthol in tobacco products has been linked to an increased likelihood of developing nicotine dependence. The widespread use of menthol can be attributed to its unique sensory characteristics; however, emerging evidence suggests that menthol also alters sensitivity to nicotine through modulation of nicotinic acetylcholine receptors (nAChRs). Nicotinic subunits, such as β2 and α5, are of interest due to their implications in nicotine reward, reinforcement, intake regulation, and aversion. This study, therefore, examined the in vivo relevance of β2 and α5 nicotinic subunits on the pharmacological and behavioral effects of menthol. Data suggests that the α5 nicotinic subunit modulates menthol intake in mice. Overall, deletion or a reduction in function of the α5 subunit lessened aversion to menthol. α5 KO mice and mice possessing the humanized α5 SNP, a variant that confers a nicotine dependence phenotype in humans, demonstrated increased menthol intake compared to their WT counterparts and in a sex-related fashion for α5 SNP mice. We further reported that the modulatory effects of the α5 subunit do not extend to other aversive tastants like quinine, suggesting that deficits in α5* nAChR signaling may not abolish general sensitivity to the aversive effects of other noxious chemicals. Further probing into the role of α5 in other pharmacological properties of menthol revealed that the α5 subunit does not modulate the antinociceptive properties of menthol in mice and suggests that the in vivo differences observed are likely not due to the direct effects of menthol on α5-containing nAChRs in vitro.
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Affiliation(s)
- Lois S Akinola
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA.
| | - Jada Gonzales
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
| | - Belle Buzzi
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
| | - Hunter L Mathews
- Department of Psychology and Neuroscience, The University of Colorado Boulder, Institute for Behavioral Genetics, Boulder, CO, USA
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Jerry A Stitzel
- Department of Psychology and Neuroscience, The University of Colorado Boulder, Institute for Behavioral Genetics, Boulder, CO, USA; Department of Integrative Physiology, The University of Colorado Boulder, Institute for Behavioral Genetics, Boulder, CO, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA
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2
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Dallanoce C, Richter K, Stokes C, Papotto C, Andleeb H, Thakur GA, Kerr A, Grau V, Papke RL. New Alpha9 nAChR Ligands Based on a 5-(Quinuclidin-3-ylmethyl)-1,2,4-oxadiazole Scaffold. ACS Chem Neurosci 2024; 15:827-843. [PMID: 38335726 PMCID: PMC11274740 DOI: 10.1021/acschemneuro.3c00720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024] Open
Abstract
Several lines of evidence have indicated that nicotinic acetylcholine receptors (nAChR) that contain α9 subunits, probably in combination with α10 subunits, may be valuable targets for the management of pain associated with inflammatory diseases through a cholinergic anti-inflammatory system (CAS), which has also been associated with α7 nAChR. Both α7- and α9-containing neuronal nAChR can be pharmacologically distinguished from the high-affinity nicotinic receptors of the brain by their sensitivity to α-bungarotoxin, but in other ways, they have quite distinct pharmacological profiles. The early association of α7 with CAS led to the development of numerous new ligands, variously characterized as α7 agonists, partial agonists, or silent agonists that desensitized α7 receptors without activation. Subsequent reinvestigation of one such family of α7 ligands based on an N,N-diethyl-N'-phenylpiperazine scaffold led to the identification of potent agonists and antagonists for α9. In this paper, we characterize the α9/α10 activity of a series of compounds based on a 5-(quinuclidin-3-ylmethyl)-1,2,4-oxadiazole (QMO) scaffold and identify two new potent ligands of α9, QMO-28, an agonist, and QMO-17, an antagonist. We separated the stereoisomers of these compounds to identify the most potent agonist and discovered that only the 3R isomer of QMO-17 was an α9 antagonist, permitting an in silico model of α9 antagonism to be developed. The α9 activity of these compounds was confirmed to be potentially useful for CAS management of inflammatory pain in cell-based assays of cytokine release.
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Affiliation(s)
- Clelia Dallanoce
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi″, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Katrin Richter
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research [DZL], Cardio-Pulmonary Institute [CPI], Giessen 35390, Germany
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, Florida 32610 United States
| | - Claudio Papotto
- Department of Pharmaceutical Sciences, Medicinal Chemistry Section "Pietro Pratesi″, University of Milan, Via L. Mangiagalli 25, 20133 Milan, Italy
| | - Hina Andleeb
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, United States
| | - Andrew Kerr
- United States Naval Research Laboratory, 6920 Washington, District of Columbia, United States
| | - Veronika Grau
- Department of General and Thoracic Surgery, Laboratory of Experimental Surgery, Justus-Liebig-University, German Center for Lung Research [DZL], Cardio-Pulmonary Institute [CPI], Giessen 35390, Germany
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, Florida 32610 United States
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3
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Shaykhutdinova ER, Severyukhina MS, Kholoshenko IV, Gondarenko EA, Shelukhina IV, Kryukova EV, Ismailova AM, Sadovnikova ES, Dyachenko IA, Murashev AN, Tsetlin VI, Utkin YN. Anti-smoking drugs cytisine and varenicline reduce cardiac reperfusion injury in rat model of myocardial ischemia. Biochimie 2024; 216:108-119. [PMID: 37871826 DOI: 10.1016/j.biochi.2023.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 10/13/2023] [Accepted: 10/16/2023] [Indexed: 10/25/2023]
Abstract
Evidence to date indicates that activation of nicotinic acetylcholine receptors (nAChRs) can reduce cardiac injury from ischemia and subsequent reperfusion. The use of nAChR agonists in various animal models leads to a reduction in reperfusion injury. Earlier this effect was shown for the agonists of α7 nAChR subtype. In this work, we demonstrated the expression of mRNA encoding α4, α6 and β2 nAChR subunits in the left ventricle of rat heart. In a rat model of myocardial ischemia, we studied the effect of α4β2 nAChR agonists cytisine and varenicline, medicines used for the treatment of nicotine addiction, and found them to significantly reduce myocardium ischemia-reperfusion injury, varenicline manifesting a higher protection. Dihydro-β-erythroidine, antagonist of α4β2 nAChR, as well as methyllycaconitine, antagonist of α7 and α6β2-containing nAChR, prevented protective effect of varenicline. This together with the presence of α4, α6 and β2 subunit mRNA in the left ventricule of rat heart raises the possibility that the varenicline effect is mediated by α4β2 as well as by α7 and/or α6β2-containing receptors. Our results point to a new way for the use of cytisine and varenicline as cardioprotective agents.
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Affiliation(s)
- Elvira R Shaykhutdinova
- Biological Testing Laboratory, Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (BIBCh RAS), 6 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Maria S Severyukhina
- Pushchino Branch of the Federal State Budgetary Educational Institution of Higher Education "Russian Biotechnological University (BIOTECH University)", 3 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Inna V Kholoshenko
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia; Mendeleev University of Chemical Technology of Russia, 9 Miusskaya square, 125047, Moscow, Russia.
| | - Elena A Gondarenko
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia.
| | - Irina V Shelukhina
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia.
| | - Elena V Kryukova
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia.
| | - Alina M Ismailova
- Biological Testing Laboratory, Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (BIBCh RAS), 6 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Elena S Sadovnikova
- Biological Testing Laboratory, Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (BIBCh RAS), 6 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Igor A Dyachenko
- Biological Testing Laboratory, Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (BIBCh RAS), 6 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Arkady N Murashev
- Biological Testing Laboratory, Branch of Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (BIBCh RAS), 6 Prospekt Nauki, 142290, Pushchino, Russia.
| | - Victor I Tsetlin
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia.
| | - Yuri N Utkin
- Department of Molecular Neuroimmune Signaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences (IBCh RAS), 16/10 Miklukho-Maklay Str., 117997, Moscow, Russia.
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4
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Papke RL. The many enigmas of nicotine. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:327-354. [PMID: 38467485 DOI: 10.1016/bs.apha.2023.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
This review discusses the diverse effects of nicotine on the various nicotinic acetylcholine receptors of the central and peripheral nervous system and how those effects may promote the usage and addiction to tobacco products.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, United States.
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5
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Rivera-Perez LM, Kwapiszewski JT, Roberts MT. α 3β 4 ∗ Nicotinic Acetylcholine Receptors Strongly Modulate the Excitability of VIP Neurons in the Mouse Inferior Colliculus. Front Neural Circuits 2021; 15:709387. [PMID: 34434092 PMCID: PMC8381226 DOI: 10.3389/fncir.2021.709387] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/19/2021] [Indexed: 12/03/2022] Open
Abstract
The inferior colliculus (IC), the midbrain hub of the central auditory system, receives extensive cholinergic input from the pontomesencephalic tegmentum. Activation of nicotinic acetylcholine receptors (nAChRs) in the IC can alter acoustic processing and enhance auditory task performance. However, how nAChRs affect the excitability of specific classes of IC neurons remains unknown. Recently, we identified vasoactive intestinal peptide (VIP) neurons as a distinct class of glutamatergic principal neurons in the IC. Here, in experiments using male and female mice, we show that cholinergic terminals are routinely located adjacent to the somas and dendrites of VIP neurons. Using whole-cell electrophysiology in brain slices, we found that acetylcholine drives surprisingly strong and long-lasting excitation and inward currents in VIP neurons. This excitation was unaffected by the muscarinic receptor antagonist atropine. Application of nAChR antagonists revealed that acetylcholine excites VIP neurons mainly via activation of α3β4∗ nAChRs, a nAChR subtype that is rare in the brain. Furthermore, we show that acetylcholine excites VIP neurons directly and does not require intermediate activation of presynaptic inputs that might express nAChRs. Lastly, we found that low frequency trains of acetylcholine puffs elicited temporal summation in VIP neurons, suggesting that in vivo-like patterns of cholinergic input can reshape activity for prolonged periods. These results reveal the first cellular mechanisms of nAChR regulation in the IC, identify a functional role for α3β4∗ nAChRs in the auditory system, and suggest that cholinergic input can potently influence auditory processing by increasing excitability in VIP neurons and their postsynaptic targets.
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Affiliation(s)
- Luis M Rivera-Perez
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, United States
| | - Julia T Kwapiszewski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, United States
| | - Michael T Roberts
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, United States
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6
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Cytisine and cytisine derivatives. More than smoking cessation aids. Pharmacol Res 2021; 170:105700. [PMID: 34087351 DOI: 10.1016/j.phrs.2021.105700] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/29/2021] [Accepted: 05/29/2021] [Indexed: 12/12/2022]
Abstract
Cytisine, a natural bioactive compound that is mainly isolated from plants of the Leguminosae family (especially the seeds of Laburnum anagyroides), has been marketed in central and eastern Europe as an aid in the clinical management of smoking cessation for more than 50 years. Its main targets are neuronal nicotinic acetylcholine receptors (nAChRs), and pre-clinical studies have shown that its interactions with various nAChR subtypes located in different areas of the central and peripheral nervous systems are neuroprotective, have a wide range of biological effects on nicotine and alcohol addiction, regulate mood, food intake and motor activity, and influence the autonomic and cardiovascular systems. Its relatively rigid conformation makes it an attractive template for research of new derivatives. Recent studies of structurally modified cytisine have led to the development of new compounds and for some of them the biological activities are mediated by still unidentified targets other than nAChRs, whose mechanisms of action are still being investigated. The aim of this review is to describe and discuss: 1) the most recent pre-clinical results obtained with cytisine in the fields of neurological and non-neurological diseases; 2) the effects and possible mechanisms of action of the most recent cytisine derivatives; and 3) the main areas warranting further research.
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7
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Scholze P, Huck S. The α5 Nicotinic Acetylcholine Receptor Subunit Differentially Modulates α4β2 * and α3β4 * Receptors. Front Synaptic Neurosci 2020; 12:607959. [PMID: 33343327 PMCID: PMC7744819 DOI: 10.3389/fnsyn.2020.607959] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/11/2020] [Indexed: 11/30/2022] Open
Abstract
Nicotine, the principal reinforcing compound in tobacco, acts in the brain by activating neuronal nicotinic acetylcholine receptors (nAChRs). This review summarizes our current knowledge regarding how the α5 accessory nAChR subunit, encoded by the CHRNA5 gene, differentially modulates α4β2* and α3β4* receptors at the cellular level. Genome-wide association studies have linked a gene cluster in chromosomal region 15q25 to increased susceptibility to nicotine addiction, lung cancer, chronic obstructive pulmonary disease, and peripheral arterial disease. Interestingly, this gene cluster contains a non-synonymous single-nucleotide polymorphism (SNP) in the human CHRNA5 gene, causing an aspartic acid (D) to asparagine (N) substitution at amino acid position 398 in the α5 nAChR subunit. Although other SNPs have been associated with tobacco smoking behavior, efforts have focused predominantly on the D398 and N398 variants in the α5 subunit. In recent years, significant progress has been made toward understanding the role that the α5 nAChR subunit—and the role of the D398 and N398 variants—plays on nAChR function at the cellular level. These insights stem primarily from a wide range of experimental models, including receptors expressed heterologously in Xenopus oocytes, various cell lines, and neurons derived from human induced pluripotent stem cells (iPSCs), as well as endogenous receptors in genetically engineered mice and—more recently—rats. Despite providing a wealth of available data, however, these studies have yielded conflicting results, and our understanding of the modulatory role that the α5 subunit plays remains incomplete. Here, we review these reports and the various techniques used for expression and analysis in order to examine how the α5 subunit modulates key functions in α4β2* and α3β4* receptors, including receptor trafficking, sensitivity, efficacy, and desensitization. In addition, we highlight the strikingly different role that the α5 subunit plays in Ca2+ signaling between α4β2* and α3β4* receptors, and we discuss whether the N398 α5 subunit variant can partially replace the D398 variant.
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Affiliation(s)
- Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Sigismund Huck
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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8
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Calarco CA, Picciotto MR. Nicotinic Acetylcholine Receptor Signaling in the Hypothalamus: Mechanisms Related to Nicotine's Effects on Food Intake. Nicotine Tob Res 2020; 22:152-163. [PMID: 30690485 DOI: 10.1093/ntr/ntz010] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Accepted: 01/17/2019] [Indexed: 12/12/2022]
Abstract
Despite health risks associated with smoking, up to 20% of the US population persist in this behavior; many smoke to control body weight or appetite, and fear of post-cessation weight gain can motivate continued smoking. Nicotine and tobacco use is associated with lower body weight, and cessation yields an average weight gain of about 4 kg, which is thought to reflect a return to the body weight of a typical nonsmoker. Nicotine replacement therapies can delay this weight gain but do not prevent it altogether, and the underlying mechanism for how nicotine is able to reduce weight is not fully understood. In rodent models, nicotine reduces weight gain, reduces food consumption, and alters energy expenditure, but these effects vary with duration and route of nicotine administration. Nicotine, acting through nicotinic acetylcholine receptors (nAChRs), increases the firing rate of both orexigenic agouti-related peptide and anorexigenic proopiomelanocortin neurons in the arcuate nucleus of the hypothalamus (ARC). Manipulation of nAChR subunit expression within the ARC can block the ability of nicotine and the nicotinic agonist cytisine from decreasing food intake; however, it is unknown exactly how this reduces food intake. This review summarizes the clinical and preclinical work on nicotine, food intake, and weight gain, then explores the feeding circuitry of the ARC and how it is regulated by nicotine. Finally, we propose a novel hypothesis for how nicotine acts on this hypothalamic circuit to reduce food intake. Implications: This review provides a comprehensive and updated summary of the clinical and preclinical work examining nicotine and food intake, as well as a summary of recent work examining feeding circuits of the hypothalamus. Synthesis of these two topics has led to new understanding of how nAChR signaling regulates food intake circuits in the hypothalamus.
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Affiliation(s)
- Cali A Calarco
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT.,Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT
| | - Marina R Picciotto
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT.,Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT
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9
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Corrie LW, Stokes C, Wilkerson JL, Carroll FI, McMahon LR, Papke RL. Nicotinic Acetylcholine Receptor Accessory Subunits Determine the Activity Profile of Epibatidine Derivatives. Mol Pharmacol 2020; 98:328-342. [PMID: 32690626 DOI: 10.1124/molpharm.120.000037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 07/02/2020] [Indexed: 12/25/2022] Open
Abstract
Epibatidine is a potent analgetic agent with very high affinity for brain nicotinic acetylcholine receptors (nAChR). We determined the activity profiles of three epibatidine derivatives, RTI-36, RTI-76, and RTI-102, which have affinity for brain nAChR equivalent to that of epibatidine but reduced analgetic activity. RNAs coding for nAChR monomeric subunits and/or concatamers were injected into Xenopus oocytes to obtain receptors of defined subunit composition and stoichiometry. The epibatidine analogs produced protracted activation of high sensitivity (HS) α4- and α2-containing receptors with the stoichiometry of 2alpha:3beta subunits but not low sensitivity (LS) receptors with the reverse ratio of alpha and beta subunits. Although not strongly activated by the epibatidine analogs, LS α4- and α2-containing receptors were potently desensitized by the epibatidine analogs. In general, the responses of α4(2)β2(2)α5 and β3α4β2α6β2 receptors were similar to those of the HS α4β2 receptors. RTI-36, the analog closest in structure to epibatidine, was the most efficacious of the three compounds, also effectively activating α7 and α3β4 receptors, albeit with lower potency and less desensitizing effect. Although not the most efficacious agonist, RTI-76 was the most potent desensitizer of α4- and α2-containing receptors. RTI-102, a strong partial agonist for HS α4β2 receptors, was effectively an antagonist for LS α4β2 receptors. Our results highlight the importance of subunit stoichiometry and the presence or absence of specific accessory subunits for determining the activity of these drugs on brain nAChR, affecting the interpretation of in vivo studies since in most cases these structural details are not known. SIGNIFICANCE STATEMENT: Epibatidine and related compounds are potent ligands for the high-affinity nicotine receptors of the brain, which are therapeutic targets and mediators of nicotine addiction. Far from being a homogeneous population, these receptors are diverse in subunit composition and vary in subunit stoichiometry. We show the importance of these structural details for drug activity profiles, which present a challenge for the interpretation of in vivo experiments since conventional methods, such as in situ hybridization and immunohistochemistry, cannot illuminate these details.
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Affiliation(s)
- Lu Wenchi Corrie
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
| | - Clare Stokes
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
| | - Jenny L Wilkerson
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
| | - F Ivy Carroll
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
| | - Lance R McMahon
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, College of Medicine (L.W.C., C.S., R.L.P.) and Department of Pharmacodynamics, College of Pharmacy, (J.L.W., L.R.M.), University of Florida, Gainesville, Florida; and Center for Drug Discovery, Research Triangle Institute, Durham, North Carolina (F.I.C.)
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10
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Hone AJ, Rueda-Ruzafa L, Gordon TJ, Gajewiak J, Christensen S, Dyhring T, Albillos A, McIntosh JM. Expression of α3β2β4 nicotinic acetylcholine receptors by rat adrenal chromaffin cells determined using novel conopeptide antagonists. J Neurochem 2020; 154:158-176. [PMID: 31967330 DOI: 10.1111/jnc.14966] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/17/2019] [Accepted: 01/13/2020] [Indexed: 01/07/2023]
Abstract
Adrenal chromaffin cells release neurotransmitters in response to stress and may be involved in conditions such as post-traumatic stress and anxiety disorders. Neurotransmitter release is triggered, in part, by activation of nicotinic acetylcholine receptors (nAChRs). However, despite decades of use as a model system for studying exocytosis, the nAChR subtypes involved have not been pharmacologically identified. Quantitative real-time PCR of rat adrenal medulla revealed an abundance of mRNAs for α3, α7, β2, and β4 subunits. Whole-cell patch-clamp electrophysiology of chromaffin cells and subtype-selective ligands were used to probe for nAChRs derived from the mRNAs found in adrenal medulla. A novel conopeptide antagonist, PeIA-5469, was created that is highly selective for α3β2 over other nAChR subtypes heterologously expressed in Xenopus laevis oocytes. Experiments using PeIA-5469 and the α3β4-selective α-conotoxin TxID revealed that rat adrenal medulla contain two populations of chromaffin cells that express either α3β4 nAChRs alone or α3β4 together with the α3β2β4 subtype. Conclusions were derived from observations that acetylcholine-gated currents in some cells were sensitive to inhibition by PeIA-5469 and TxID, while in other cells, currents were sensitive only to TxID. Expression of functional α7 nAChRs was determined using three α7-selective ligands: the agonist PNU282987, the positive allosteric modulator PNU120596, and the antagonist α-conotoxin [V11L,V16D]ArIB. The results of these studies identify for the first time the expression of α3β2β4 nAChRs as well as functional α7 nAChRs by rat adrenal chromaffin cells.
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Affiliation(s)
- Arik J Hone
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA.,Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Lola Rueda-Ruzafa
- Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain.,Biomedical Research Center (CINBIO), University of Vigo, Vigo, Spain
| | - Thomas J Gordon
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | - Joanna Gajewiak
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | - Sean Christensen
- School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA
| | | | - Almudena Albillos
- Departament of Pharmacology and Therapeutics, Universidad Autónoma de Madrid, Madrid, Spain
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA.,School of Biological Sciences and University of Utah, Salt Lake City, Utah, USA.,Department of Psychiatry, University of Utah, Salt Lake City, Utah, USA
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11
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Calarco CA, Li Z, Taylor SR, Lee S, Zhou W, Friedman JM, Mineur YS, Gotti C, Picciotto MR. Molecular and cellular characterization of nicotinic acetylcholine receptor subtypes in the arcuate nucleus of the mouse hypothalamus. Eur J Neurosci 2018; 48:10.1111/ejn.13966. [PMID: 29791746 PMCID: PMC6251769 DOI: 10.1111/ejn.13966] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/26/2018] [Accepted: 05/09/2018] [Indexed: 12/22/2022]
Abstract
Nicotine, acting through nicotinic acetylcholine receptors (nAChRs), increases the firing rate of both orexigenic agouti-related peptide (AgRP) and anorexigenic pro-opiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARC), yet nicotine and other nAChR agonists decrease food intake in mice. Viral-mediated knockdown of the β4 nAChR subunit in all neuronal cell types in the ARC prevents the nicotinic agonist cytisine from decreasing food intake, but it is not known whether the β4 subunit is selectively expressed in anorexigenic neurons or how other nAChR subtypes are distributed in this nucleus. Using translating ribosome affinity purification (TRAP) on ARC tissue from mice with ribosomes tagged in either AgRP or POMC cells, we examined nAChR subunit mRNA levels using real-time PCR. Both AgRP and POMC cells express a comparable panel of nAChR subunits with differences in α7 mRNA levels and a trend for difference in α4 levels, but no differences in β4 expression. Immunoprecipitation of assembled nAChRs revealed that the β4 subunit forms assembled channels with α3, β2 and α4, but not other subunits found in the ARC. Finally, using cell type-selective, virally delivered small hairpin RNAs targeting either the β4 or α7 subunit, we examined the contribution of each subunit in either AgRP or POMC cells to the behavioural response to nicotine, refining the understanding of nicotinic regulation of this feeding circuit. These experiments identify a more complex set of nAChRs expressed in ARC than in other hypothalamic regions. Thus, the ARC appears to be a particular target of nicotinic modulation.
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Affiliation(s)
- Cali A. Calarco
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
| | | | - Seth R. Taylor
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
| | - Somin Lee
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
| | - Wenliang Zhou
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
| | | | - Yann S. Mineur
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
| | | | - Marina R. Picciotto
- Department of Psychiatry and Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06508, USA
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12
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Bagdas D, Alkhlaif Y, Jackson A, Carroll FI, Ditre JW, Damaj MI. New insights on the effects of varenicline on nicotine reward, withdrawal and hyperalgesia in mice. Neuropharmacology 2018; 138:72-79. [PMID: 29860196 DOI: 10.1016/j.neuropharm.2018.05.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 05/16/2018] [Accepted: 05/19/2018] [Indexed: 12/16/2022]
Abstract
Varenicline, a partial agonist for α4β2* nicotinic acetylcholine receptors (nAChRs) and a full agonist for α3β4 and α7 nAChRs, is approved for smoking cessation treatment. Although, partial agonism at α4β2* nAChRs is believed to be the mechanism underlying the effects of varenicline on nicotine reward, the contribution of other nicotinic subtypes to varenicline's effects on nicotine reward is currently unknown. Therefore, we examined the role of α5 and α7 nAChR subunits in the effects of varenicline on nicotine reward using the conditioned place preference (CPP) test in mice. Moreover, the effects of varenicline on nicotine withdrawal-induced hyperalgesia and aversion are unknown. We also examined the reversal of nicotine withdrawal in mouse models of dependence by varenicline. Varenicline dose-dependently blocked the development and expression of nicotine reward in the CPP test. The blockade of nicotine reward by varenicline (0.1 mg/kg) was preserved in α7 knockout mice but reduced in α5 knockout mice. Administration of varenicline at high dose of 2.5 mg/kg resulted in a place aversion that was dependent on α5 nAChRs but not β2 nAChRs. Furthermore, varenicline (0.1 and 0.5 mg/kg) reversed nicotine withdrawal signs such as hyperalgesia and somatic signs and withdrawal-induced aversion in a dose-related manner. Our results indicate that the α5 nAChR subunit plays a role in the effects of varenicline on nicotine reward in mice. Moreover, the mediation of α5 nAChRs, but not β2 nAChRs are probably needed for aversive properties of varenicline at high dose. Varenicline was also shown to reduce several nicotine withdrawal signs.
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Affiliation(s)
- Deniz Bagdas
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, United States.
| | - Yasmin Alkhlaif
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States
| | - Asti Jackson
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States
| | - F Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC, United States
| | - Joseph W Ditre
- Department of Psychology, Syracuse University, Syracuse, NY, United States
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States; The Center for the Study for Tobacco Products, Virginia Commonwealth University, Richmond, VA, United States
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13
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Crespi A, Plutino S, Sciaccaluga M, Righi M, Borgese N, Fucile S, Gotti C, Colombo SF. The fifth subunit in α3β4 nicotinic receptor is more than an accessory subunit. FASEB J 2018; 32:4190-4202. [PMID: 29505300 DOI: 10.1096/fj.201701377r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The α3β4 subtype is the predominant neuronal nicotinic acetylcholine receptor present in the sensory and autonomic ganglia and in a subpopulation of brain neurons. This subtype can form pentameric receptors with either 2 or 3 β4 subunits that have different pharmacologic and functional properties. To further investigate the role of the fifth subunit, we coexpressed a dimeric construct coding for a single polypeptide containing the β4 and α3 subunit sequences, with different monomeric subunits. With this strategy, which allowed the formation of single populations of receptors with unique stoichiometry, we demonstrated with immunofluorescence and biochemical and functional assays that only the receptors with 3 β4 subunits are efficiently expressed at the plasma membrane. Moreover, the LFM export motif of β4 subunit in the fifth position exerts a unique function in the regulation of the intracellular trafficking of the receptors, their exposure at the cell surface, and consequently, their function, whereas the same export motif present in the β4 subunits forming the acetylcholine binding site is dispensable.-Crespi, A., Plutino, S., Sciaccaluga, M., Righi, M., Borgese, N., Fucile, S., Gotti, C., Colombo, S. F. The fifth subunit in α3β4 nicotinic receptor is more than an accessory subunit.
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Affiliation(s)
- Arianna Crespi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Consiglio Nazionale delle Ricerche (CNR) Institute of Neuroscience, Milan, Italy
| | - Simona Plutino
- Dipartimento di Fisiologia e Farmacologia, Università di Roma La Sapienza, Rome, Italy; and
| | - Miriam Sciaccaluga
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, Istituto Neurologico Mediterraneo, Pozzilli, Italy
| | - Marco Righi
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Consiglio Nazionale delle Ricerche (CNR) Institute of Neuroscience, Milan, Italy
| | - Nica Borgese
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Consiglio Nazionale delle Ricerche (CNR) Institute of Neuroscience, Milan, Italy
| | - Sergio Fucile
- Dipartimento di Fisiologia e Farmacologia, Università di Roma La Sapienza, Rome, Italy; and.,Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, Istituto Neurologico Mediterraneo, Pozzilli, Italy
| | - Cecilia Gotti
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Consiglio Nazionale delle Ricerche (CNR) Institute of Neuroscience, Milan, Italy
| | - Sara Francesca Colombo
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.,Consiglio Nazionale delle Ricerche (CNR) Institute of Neuroscience, Milan, Italy
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14
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Hone AJ, McIntosh JM. Nicotinic acetylcholine receptors in neuropathic and inflammatory pain. FEBS Lett 2017; 592:1045-1062. [PMID: 29030971 DOI: 10.1002/1873-3468.12884] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/22/2017] [Accepted: 10/05/2017] [Indexed: 01/11/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are actively being investigated as therapeutic targets for the treatment of pain and inflammation, but despite more than 30 years of research, there are currently no FDA-approved analgesics that are specific for these receptors. Much of the initial research effort focused on the α4β2 nAChR subtype, but more recently, additional subtypes have been identified as promising new leads and include α6β4, α7, and α9-containing nAChRs. This Review will focus on the distribution of these nAChRs in the cell types involved in neuropathic pain and inflammation and the activity of currently available nicotinic ligands.
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Affiliation(s)
- Arik J Hone
- Department of Biology, University of Utah, Salt Lake City, UT, USA
| | - J Michael McIntosh
- Department of Biology, University of Utah, Salt Lake City, UT, USA.,Department of Psychiatry, University of Utah, Salt Lake City, UT, USA.,George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, USA
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15
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Albillos A, McIntosh JM. Human nicotinic receptors in chromaffin cells: characterization and pharmacology. Pflugers Arch 2017; 470:21-27. [PMID: 29058146 DOI: 10.1007/s00424-017-2073-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 02/03/2023]
Abstract
During the last 10 years, we have been working on human chromaffin cells obtained from the adrenal gland of organ donors that suffered encephalic or cardiac death. We first electrophysiologically characterized the nicotinic acetylcholine receptors (nAChRs) activated by acetylcholine, and their contribution to the exocytosis of chromaffin vesicles and release of catecholamines. We have shown that these cells possess an adrenergic phenotype. This phenotype may contribute to an increased expression of α7 nAChRs in these cells, allowing for recording of α7 nAChR currents, something that had previously not been achieved in non-human species. The use of α-conotoxins allowed us to characterize non-α7 nAChR subtypes and, together with molecular biology experiments, conclude that the predominant nAChR subtype in human chromaffin cells is α3β4* (asterisk indicates the posible presence of additional subunits). In addition, there is a minor population of αxβ2 nAChRs. Both α7 and non-α7 nAChR subtypes contribute to the exocytotic process. Exocytosis mediated by nAChRs could be as large in magnitude as that elicited by calcium entry through voltage-dependent calcium channels. Finally, we have also investigated the effect of nAChR-targeted tobacco cessation drugs on catecholamine release in chromaffin cells. We have concluded that at therapeutic concentrations, varenicline alone does not increase the frequency of action potentials evoked by ACh. However, varenicline in the presence of nicotine does increase this frequency, and thus, in the presence of both drugs, the probability of increased catecholamine release in human chromaffin cells is high.
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Affiliation(s)
- Almudena Albillos
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Calle Arzobispo Morcillo 4, 28029, Madrid, Spain.
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Biology, University of Utah, Salt Lake City, UT, USA.,Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
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16
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Hone AJ, Michael McIntosh J, Rueda-Ruzafa L, Passas J, de Castro-Guerín C, Blázquez J, González-Enguita C, Albillos A. Therapeutic concentrations of varenicline in the presence of nicotine increase action potential firing in human adrenal chromaffin cells. J Neurochem 2016; 140:37-52. [PMID: 27805736 DOI: 10.1111/jnc.13883] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 10/20/2016] [Accepted: 10/27/2016] [Indexed: 01/13/2023]
Abstract
Varenicline is a nicotinic acetylcholine receptor (nAChR) agonist used to treat nicotine addiction, but a live debate persists concerning its mechanism of action in reducing nicotine consumption. Although initially reported as α4β2 selective, varenicline was subsequently shown to activate other nAChR subtypes implicated in nicotine addiction including α3β4. However, it remains unclear whether activation of α3β4 nAChRs by therapeutically relevant concentrations of varenicline is sufficient to affect the behavior of cells that express this subtype. We used patch-clamp electrophysiology to assess the effects of varenicline on native α3β4* nAChRs (asterisk denotes the possible presence of other subunits) expressed in human adrenal chromaffin cells and compared its effects to those of nicotine. Varenicline and nicotine activated α3β4* nAChRs with EC50 values of 1.8 (1.2-2.7) μM and 19.4 (11.1-33.9) μM, respectively. Stimulation of adrenal chromaffin cells with 10 ms pulses of 300 μM acetylcholine (ACh) in current-clamp mode evoked sodium channel-dependent action potentials (APs). Under these conditions, perfusion of 50 or 100 nM varenicline showed very little effect on AP firing compared to control conditions (ACh stimulation alone), but at higher concentrations (250 nM) varenicline increased the number of APs fired up to 436 ± 150%. These results demonstrate that therapeutic concentrations of varenicline are unlikely to alter AP firing in chromaffin cells. In contrast, nicotine showed no effect on AP firing at any of the concentrations tested (50, 100, 250, and 500 nM). However, perfusion of 50 nM nicotine simultaneously with 100 nM varenicline increased AP firing by 290 ± 104% indicating that exposure to varenicline and nicotine concurrently may alter cellular behavior such as excitability and neurotransmitter release.
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Affiliation(s)
- Arik J Hone
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.,Departments of Biology, University of Utah, Salt Lake City, Utah, USA
| | - J Michael McIntosh
- Departments of Biology, University of Utah, Salt Lake City, Utah, USA.,Psychiatry, University of Utah, Salt Lake City, Utah, USA.,The George E. Whalen Veterans Affairs Medical Center, Salt Lake City, Utah, USA
| | - Lola Rueda-Ruzafa
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | | | | | | | | | - Almudena Albillos
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
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17
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Onajole OK, Vallerini GP, Eaton JB, Lukas RJ, Brunner D, Caldarone BJ, Kozikowski AP. Synthesis and Behavioral Studies of Chiral Cyclopropanes as Selective α4β2-Nicotinic Acetylcholine Receptor Partial Agonists Exhibiting an Antidepressant Profile. Part III. ACS Chem Neurosci 2016; 7:811-22. [PMID: 27035276 DOI: 10.1021/acschemneuro.6b00050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We report the synthesis and biological characterization of novel derivatives of 3-[(1-methyl-2(S)-pyrrolidinyl)methoxy]-5-cyclopropylpyridine (4a-f and 5) as potent and highly selective α4β2-nicotinic acetylcholine receptor (nAChR) full or partial agonists. A systematic structure-activity study was carried out on the previously described compound 3b, particularly concerning its (2-methoxyethyl)cyclopropyl side-chain, in an effort to improve its metabolic stability while maintaining receptor selectivity. Compound 4d exhibited very similar subnanomolar binding affinity for α4β2- and α4β2*-nAChRs compared to 3b, and it showed excellent potency in activating high-sensitivity (HS) α4β2-nAChRs with an EC50 value of 8.2 nM. Testing of 4d in the SmartCube assay revealed that the compound has a combined antidepressant plus antipsychotic signature. In the forced swim test at a dose of 30 mg/kg given intraperitoneally, 4d was found to be as efficacious as sertraline, thus providing evidence of the potential use of the compound as an antidepressant. Additional promise for use of 4d in humans comes from pharmacokinetic studies in mice indicating brain penetration, and additional assays show compound stability in the presence of human microsomes and hepatocytes. Thus, 4d has a very favorable preclinical drug profile.
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Affiliation(s)
- Oluseye K. Onajole
- Drug
Discovery Program, Department of Medicinal Chemistry and Pharmacognosy,
College of Pharmacy, University of Illinois at Chicago, 833 South
Wood Street, Chicago, Illinois 60612, United States
- Department
of Biological, Chemical and Physical Sciences, Roosevelt University, 425 S. Wabash Avenue, Chicago, Illinois 60605, United States
| | - Gian Paolo Vallerini
- Drug
Discovery Program, Department of Medicinal Chemistry and Pharmacognosy,
College of Pharmacy, University of Illinois at Chicago, 833 South
Wood Street, Chicago, Illinois 60612, United States
| | - J. Brek Eaton
- Division
of Neurobiology, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013, United States
| | - Ronald J. Lukas
- Division
of Neurobiology, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013, United States
| | - Dani Brunner
- PsychoGenics, Inc., 765 Old Saw Mill
River Road, Tarrytown, New
York 10591, United States
| | - Barbara J. Caldarone
- Harvard
NeuroDiscovery Center and Department of Neurology, Brigham and Women’s Hospital, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Alan P. Kozikowski
- Drug
Discovery Program, Department of Medicinal Chemistry and Pharmacognosy,
College of Pharmacy, University of Illinois at Chicago, 833 South
Wood Street, Chicago, Illinois 60612, United States
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18
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Radchenko EV, Dravolina OA, Bespalov AY. Agonist and antagonist effects of cytisine in vivo. Neuropharmacology 2015; 95:206-14. [DOI: 10.1016/j.neuropharm.2015.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 02/22/2015] [Accepted: 03/14/2015] [Indexed: 12/15/2022]
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19
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Tuan EW, Horti AG, Olson TT, Gao Y, Stockmeier CA, Al-Muhtasib N, Bowman Dalley C, Lewin AE, Wolfe BB, Sahibzada N, Xiao Y, Kellar KJ. AT-1001 Is a Partial Agonist with High Affinity and Selectivity at Human and Rat α3β4 Nicotinic Cholinergic Receptors. Mol Pharmacol 2015; 88:640-9. [PMID: 26162864 DOI: 10.1124/mol.115.099978] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/08/2015] [Indexed: 11/22/2022] Open
Abstract
AT-1001 [N-(2-bromophenyl)-9-methyl-9-azabicyclo[3.3.1] nonan-3-amine] is a high-affinity and highly selective ligand at α3β4 nicotinic cholinergic receptors (nAChRs) that was reported to decrease nicotine self-administration in rats. It was initially reported to be an antagonist at rat α3β4 nAChRs heterologously expressed in HEK293 cells. Here we compared AT-1001 actions at rat and human α3β4 and α4β2 nAChRs similarly expressed in HEK 293 cells. We found that, as originally reported, AT-1001 is highly selective for α3β4 receptors over α4β2 receptors, but its binding selectivity is much greater at human than at rat receptors, because of a higher affinity at human than at rat α3β4 nAChRs. Binding studies in human and rat brain and pineal gland confirmed the selectivity of AT-1001 for α3β4 nAChRs and its higher affinity for human compared with rat receptors. In patch-clamp electrophysiology studies, AT-1001 was a potent partial agonist with 65-70% efficacy at both human and rat α3β4 nAChRs. It was also a less potent and weaker (18%) partial agonist at α4β2 nAChRs. Both α3β4 and α4β2 nAChRs are upregulated by exposure of cells to AT-1001 for 3 days. Similarly, AT-1001 desensitized both receptor subtypes in a concentration-dependent manner, but it was 10 and 30 times more potent to desensitize human α3β4 receptors than rat α3β4 and human α4β2 receptors, respectively. After exposure to AT-1001, the time to recovery from desensitization was longest for the human α3β4 nAChR and shortest for the human α4β2 receptor, suggesting that recovery from desensitization is primarily related to the dissociation of the ligand from the receptor.
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Affiliation(s)
- Edward W Tuan
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Andrew G Horti
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Thao T Olson
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Yongiun Gao
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Craig A Stockmeier
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Nour Al-Muhtasib
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Carrie Bowman Dalley
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Amanda E Lewin
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Barry B Wolfe
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Niaz Sahibzada
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Yingxian Xiao
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
| | - Kenneth J Kellar
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, Washington, DC (E.W.T., T.T.O., N.A.-M., C.B.D., A.E.L., B.B.W., N.S., Y.X., K.J.K.); Department of Radiology Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland (A.G.H., Y.G.); and Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, Mississippi (C.A.S.)
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Shorey-Kendrick LE, Ford MM, Allen DC, Kuryatov A, Lindstrom J, Wilhelm L, Grant KA, Spindel ER. Nicotinic receptors in non-human primates: Analysis of genetic and functional conservation with humans. Neuropharmacology 2015; 96:263-73. [PMID: 25661700 PMCID: PMC4486519 DOI: 10.1016/j.neuropharm.2015.01.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 01/20/2015] [Accepted: 01/22/2015] [Indexed: 01/18/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are highly conserved between humans and non-human primates. Conservation exists at the level of genomic structure, protein structure and epigenetics. Overall homology of nAChRs at the protein level is 98% in macaques versus 89% in mice, which is highly relevant for evaluating subtype-specific ligands that have different affinities in humans versus rodents. In addition to conservation at the protein level, there is high conservation of genomic structure in terms of intron and exon size and placement of CpG sites that play a key role in epigenetic regulation. Analysis of single nucleotide polymorphisms (SNPs) shows that while the majority of SNPs are not conserved between humans and macaques, some functional polymorphisms are. Most significantly, cynomolgus monkeys express a similar α5 nAChR Asp398Asn polymorphism to the human α5 Asp398Asn polymorphism that has been linked to greater nicotine addiction and smoking related disease. Monkeys can be trained to readily self-administer nicotine, and in an initial study we have demonstrated that cynomolgus monkeys bearing the α5 D398N polymorphism show a reduced behavioral sensitivity to oral nicotine and tend to consume it in a different pattern when compared to wild-type monkeys. Thus the combination of highly homologous nAChR, higher cortical functions and capacity for complex training makes non-human primates a unique model to study in vivo functions of nicotinic receptors. In particular, primate studies on nicotine addiction and evaluation of therapies to prevent or overcome nicotine addiction are likely to be highly predictive of treatment outcomes in humans.
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Affiliation(s)
- Lyndsey E Shorey-Kendrick
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
| | - Matthew M Ford
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
| | - Daicia C Allen
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
| | - Alexander Kuryatov
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Jon Lindstrom
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Larry Wilhelm
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
| | - Kathleen A Grant
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
| | - Eliot R Spindel
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health &, Science University, Beaverton, OR 97006, USA.
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21
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Onajole OK, Eaton JB, Lukas RJ, Brunner D, Thiede L, Caldarone BJ, Kozikowski AP. Enantiopure Cyclopropane-Bearing Pyridyldiazabicyclo[3.3.0]octanes as Selective α4β2-nAChR Ligands. ACS Med Chem Lett 2014; 5:1196-201. [PMID: 25408831 DOI: 10.1021/ml500129k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 09/29/2014] [Indexed: 01/24/2023] Open
Abstract
We report the synthesis and characterization of a series of enantiopure 5-cyclopropane-bearing pyridyldiazabicyclo[3.3.0]octanes that display low nanomolar binding affinities and act as functional agonists at α4β2-nicotinic acetylcholine receptor (nAChR) subtype. Structure-activity relationship studies revealed that incorporation of a cyclopropane-containing side chain at the 5-position of the pyridine ring provides ligands with improved subtype selectivity for nAChR β2 subunit-containing nAChR subtypes (β2*-nAChRs) over β4*-nAChRs compared to the parent compound 4. Compound 15 exhibited subnanomolar binding affinity for α4β2- and α4β2*-nAChRs with negligible interaction. Functional assays confirm selectivity for α4β2-nAChRs. Furthermore, using the SmartCube assay system, this ligand showed antidepressant, anxiolytic, and antipsychotic features, while mouse forced-swim assay further confirm the antidepressant-like property of 15.
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Affiliation(s)
- Oluseye K. Onajole
- Department
of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, United States
| | - J. Brek Eaton
- Division
of Neurobiology, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013, United States
| | - Ronald J. Lukas
- Division
of Neurobiology, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, Arizona 85013, United States
| | - Dani Brunner
- PsychoGenics, Inc., 765 Old Saw Mill
River Road, Tarrytown, New
York 10591, United States
| | - Lucinda Thiede
- PsychoGenics, Inc., 765 Old Saw Mill
River Road, Tarrytown, New
York 10591, United States
| | - Barbara J. Caldarone
- NeuroBehavior
Laboratory, Harvard NeuroDiscovery Center and Department of Neurology, Brigham and Women’s Hospital, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
| | - Alan P. Kozikowski
- Department
of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, United States
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22
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Moretti M, Zoli M, George AA, Lukas RJ, Pistillo F, Maskos U, Whiteaker P, Gotti C. The novel α7β2-nicotinic acetylcholine receptor subtype is expressed in mouse and human basal forebrain: biochemical and pharmacological characterization. Mol Pharmacol 2014; 86:306-17. [PMID: 25002271 DOI: 10.1124/mol.114.093377] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined α7β2-nicotinic acetylcholine receptor (α7β2-nAChR) expression in mammalian brain and compared pharmacological profiles of homomeric α7-nAChRs and α7β2-nAChRs. α-Bungarotoxin affinity purification or immunoprecipitation with anti-α7 subunit antibodies (Abs) was used to isolate nAChRs containing α7 subunits from mouse or human brain samples. α7β2-nAChRs were detected in forebrain, but not other tested regions, from both species, based on Western blot analysis of isolates using β2 subunit-specific Abs. Ab specificity was confirmed in control studies using subunit-null mutant mice or cell lines heterologously expressing specific human nAChR subtypes and subunits. Functional expression in Xenopus oocytes of concatenated pentameric (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs was confirmed using two-electrode voltage clamp recording of responses to nicotinic ligands. Importantly, pharmacological profiles were indistinguishable for concatenated (α7)5-nAChRs or for homomeric α7-nAChRs constituted from unlinked α7 subunits. Pharmacological profiles were similar for (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs except for diminished efficacy of nicotine (normalized to acetylcholine efficacy) at α7β2- versus α7-nAChRs. This study represents the first direct confirmation of α7β2-nAChR expression in human and mouse forebrain, supporting previous mouse studies that suggested relevance of α7β2-nAChRs in Alzheimer disease etiopathogenesis. These data also indicate that α7β2-nAChR subunit isoforms with different α7/β2 subunit ratios have similar pharmacological profiles to each other and to α7 homopentameric nAChRs. This supports the hypothesis that α7β2-nAChR agonist activation predominantly or entirely reflects binding to α7/α7 subunit interface sites.
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Affiliation(s)
- Milena Moretti
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Michele Zoli
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Andrew A George
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Ronald J Lukas
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Francesco Pistillo
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Uwe Maskos
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Paul Whiteaker
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Cecilia Gotti
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
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23
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Papke RL, Chojnacka K, Horenstein NA. The minimal pharmacophore for silent agonism of the α7 nicotinic acetylcholine receptor. J Pharmacol Exp Ther 2014; 350:665-80. [PMID: 24990939 DOI: 10.1124/jpet.114.215236] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The minimum pharmacophore for activation of the human α7 nicotinic acetylcholine receptor (nAChR) is the tetramethylammonium cation. Previous work demonstrated that larger quaternary ammonium compounds, such as diethyldimethylammonium or 1-methyl quinuclidine, were α7-selective partial agonists, but additional increase in the size of the ammonium cation or the quinuclidine N-alkyl group by a single carbon to an N-ethyl group led to a loss of efficacy for ion channel activation. We report that although such compounds are ineffective at inducing the normal channel open state, they nonetheless regulate the induction of specific conformational states normally considered downstream of channel activation. We synthesized several panels of quaternary ammonium nAChR ligands that systematically varied the size of the substituents bonded to the central positively charged nitrogen atom. In these molecular series, we found a correlation between the molecular volume of the ligand and/or charge density, and the receptor's preferred distribution among conformational states including the closed state, the active state, a nonconducting state that could be converted to an activated state by a positive allosteric modulator (PAM), and a PAM-insensitive nonconducting state. We hypothesize that the changes of molecular volume of an agonist's cationic core subtly impact interactions at the subunit interface constituting the orthosteric binding site in such a way as to regulate the probability of conversions among the conformational states. We define a new minimal pharmacophore for the class of compounds we have termed "silent agonists," which are able to induce allosteric modulator-dependent activation but not the normal activated state.
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Affiliation(s)
- Roger L Papke
- Departments of Pharmacology and Therapeutics (R.L.P.) and Chemistry (K.C., N.A.H.), University of Florida, Gainesville, Florida
| | - Kinga Chojnacka
- Departments of Pharmacology and Therapeutics (R.L.P.) and Chemistry (K.C., N.A.H.), University of Florida, Gainesville, Florida
| | - Nicole A Horenstein
- Departments of Pharmacology and Therapeutics (R.L.P.) and Chemistry (K.C., N.A.H.), University of Florida, Gainesville, Florida
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Rollema H, Russ C, Lee TC, Hurst RS, Bertrand D. Functional interactions of varenicline and nicotine with nAChR subtypes implicated in cardiovascular control. Nicotine Tob Res 2014; 16:733-42. [PMID: 24406270 DOI: 10.1093/ntr/ntt208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION It has been suggested that varenicline-induced activation of nicotinic acetylcholine receptors (nAChRs) could play a role in the cardiovascular (CV) safety of varenicline. However, since preclinical studies showed that therapeutic varenicline concentrations have no effect in models of CV function, this study examined in vitro profiles of varenicline and nicotine at nAChR subtypes possibly involved in CV control. METHODS Concentration-dependent functional effects of varenicline and nicotine at human α3β4, α3α5β4, α7, and α4β2 nAChRs expressed in oocytes were determined by electrophysiology. The proportion of nAChRs predicted to be activated and inhibited by concentrations of varenicline (1mg b.i.d.) and of nicotine in smokers was derived from activation-inhibition curves for each nAChR subtype. RESULTS Human varenicline and nicotine concentrations can desensitize and inhibit nAChRs but cause only low-level activation of α3β4, α4β2 (<2%), α7 (<0.05%), and α3α5β4 (<0.01%) nAChRs, which is consistent with literature data. Nicotine concentrations in smokers are predicted to inhibit larger fractions of α3β4 (48%) and α3α5β4 (10%) nAChRs than therapeutic varenicline concentrations (11% and 0.6%, respectively) and to inhibit comparable fractions of α4β2 nAChRs (42%-56%) and α7 nAChRs (16%) as varenicline. CONCLUSIONS Nicotine and varenicline concentrations in patients and smokers are predicted to cause minimal activation of ganglionic α3β4* nAChRs, while their functional profiles at α3β4, α3α5β4, α7, and α4β2 nAChRs cannot explain that substituting nicotine from tobacco with varenicline would cause CV adverse events in smokers who try to quit. Other pharmacological properties that could mediate varenicline-induced CV effects have not been identified.
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25
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Varenicline and cytisine diminish the dysphoric-like state associated with spontaneous nicotine withdrawal in rats. Neuropsychopharmacology 2014; 39:455-65. [PMID: 23966067 PMCID: PMC3870769 DOI: 10.1038/npp.2013.216] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/07/2013] [Accepted: 08/11/2013] [Indexed: 02/04/2023]
Abstract
Tobacco addiction is characterized by a negative mood state upon smoking cessation and relapse after periods of abstinence. Clinical studies indicate that negative mood states lead to craving and relapse. The partial α4/α6/β2* nicotinic acetylcholine receptor (nAChR) agonists varenicline and cytisine are widely used as smoking cessation treatments. Varenicline has been approved in the United States for smoking cessation and cytisine is used in Eastern European countries. Despite the widespread use of these compounds, very little is known about their effects on mood states. These studies investigated the effects of varenicline, cytisine, and the cytisine-derivative 3-(pyridin-3'-yl)-cytisine (3-pyr-Cyt) on brain reward function in nicotine-naive and nicotine-withdrawing rats. The cytisine-derivative 3-pyr-Cyt is a very weak α4β2* nAChR partial agonist and like cytisine and varenicline has antidepressant-like effects in animal models. The intracranial self-stimulation (ICSS) procedure was used to investigate the effects of these compounds on brain reward function. Elevations in ICSS thresholds reflect a dysphoric state and a lowering of thresholds is indicative of a potentiation of brain reward function. It was shown that acute administration of nicotine and varenicline lowered ICSS thresholds. Acute administration of cytisine or 3-pyr-Cyt did not affect ICSS thresholds. Discontinuation of chronic, 14 days, nicotine administration led to elevations in ICSS thresholds that lasted for about 2 days. Varenicline and cytisine, but not 3-pyr-Cyt, diminished the nicotine withdrawal-induced elevations in ICSS thresholds. In conclusion, these studies indicate that varenicline and cytisine diminish the dysphoric-like state associated with nicotine withdrawal and may thereby prevent relapse to smoking in humans.
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Papke RL, Stokes C, Muldoon P, Imad Damaj M. Similar activity of mecamylamine stereoisomers in vitro and in vivo. Eur J Pharmacol 2013; 720:264-75. [PMID: 24161916 DOI: 10.1016/j.ejphar.2013.10.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
A previous characterization of mecamylamine stereoisomers using nicotinic acetylcholine receptors expressed in Xenopus oocytes revealed only small differences between the activity of the R and S forms of mecamylamine. However, that work was limited in the breadth of receptor subtypes tested, especially in regard to the discrimination of high and low sensitivity receptors, which differ in the ratios of alpha and beta subunits. We report new data using subunit concatamers, which produce uniform populations of high-sensitivity or low-sensitivity receptors, as well as alpha2, alpha5, and alpha6-containing receptors, which were not studied previously. Consistent with previous studies, we found that beta4-containing receptors were most sensitive to mecamylamine and that the IC50 values for the inhibition of net charge were lower than for inhibition of peak currents. No large differences were seen between the activities of the mecamylamine isomers. Additionally, a previously reported potentiation of high-sensitivity α4β2 receptors by S-mecamylamine could not be reproduced in the oocyte system, even with mutants that had greatly reduced sensitivity to mecamylamine inhibition or when the selective agonist TC-2559 was used. In vivo studies suggested that the R-isomer might be somewhat more potent than the S isomer at blocking CNS effects of nicotine. Although the potency difference was no more than a factor of two, it is consistent with lower LD50 estimates previously reported for the R isomer. Our results significantly extend knowledge of the nicotinic acetylcholine receptor activity profile of mecamylamine and support the hypothesis that these effects are not strongly stereoisomer selective.
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Affiliation(s)
- Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, Florida, USA.
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27
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Peng C, Stokes C, Mineur YS, Picciotto MR, Tian C, Eibl C, Tomassoli I, Guendisch D, Papke RL. Differential modulation of brain nicotinic acetylcholine receptor function by cytisine, varenicline, and two novel bispidine compounds: emergent properties of a hybrid molecule. J Pharmacol Exp Ther 2013; 347:424-37. [PMID: 23959137 DOI: 10.1124/jpet.113.206904] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Partial agonist therapies for the treatment of nicotine addiction and dependence depend on both agonistic and antagonistic effects of the ligands, and side effects associated with other nAChRs greatly limit the efficacy of nicotinic partial agonists. We evaluated the in vitro pharmacological properties of four partial agonists, two current smoking cessation drugs, varenicline and cytisine, and two novel bispidine compounds, BPC and BMSP, by using defined nAChR subtypes expressed in Xenopus laevis oocytes and human embryonic kidney 293 cells. Similar to varenicline and cytisine, BPC and BMSP are partial agonists of α4β2 nAChRs, although BMSP produced very little activation of these receptors. Unlike varenicline and cytisine, BPC and BMSP showed desired low activity. BPC produced mecamylamine-sensitive steady-state activation of α4* receptors that was not evident with BMSP. We evaluated the modulation of α4*- and α7-mediated responses in rat lateral geniculate nucleus (LGN) neurons and hippocampal stratum radiatum (SR) interneurons, respectively. The LGN neurons were sensitive to a very low concentration of varenicline, and the SR interneuron responses were also sensitive to varenicline at a submicromolar concentration. Although 300 nM BPC strongly inhibited the ACh-evoked responses of LGN neurons, it did not inhibit the α7 currents of SR interneurons. Similar results were observed with 300 nM BMSP. Additionally, the bispidine compounds were efficacious in the mouse tail suspension test, demonstrating that they affect receptors in the brain when delivered systemically. Our data indicate that BPC and BMSP are promising α4β2* partial agonists for pharmacotherapeutics.
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Affiliation(s)
- Can Peng
- Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, Florida (C.P., C.S., C.T., R.L.P.); Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut (Y.S.M., M.R.P.); and Department of Pharmaceutical Sciences, College of Pharmacy, University of Hawaii, Hilo, Hawaii (C.E., I.T., D.G.)
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28
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The effects of noncontingent and self-administered cytisine on body weight and meal patterns in male Sprague-Dawley rats. Pharmacol Biochem Behav 2013; 110:192-200. [PMID: 23876236 DOI: 10.1016/j.pbb.2013.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 07/02/2013] [Accepted: 07/13/2013] [Indexed: 01/30/2023]
Abstract
RATIONALE Increased appetite and weight gain after cessation are deterrents for quitting smoking. Pharmacotherapies that can reduce this weight gain in ex-smokers would be invaluable, and yet are not well studied in this context. OBJECTIVE To examine the effects of extended daily exposure to intravenous cytisine, an alpha4beta2 nAChR partial agonist used for smoking cessation in some European countries, on body weight and patterns of food intake in rats. METHODS In the first experiment, programmed infusions of cytisine were administered over 15 h per day. Food intake, meal patterns, and weight change were examined relative to a vehicle-infused group during treatment, and in a post-cytisine phase. The second experiment examined the effects of cytisine on food intake, meal patterns, and weight change when substituted for nicotine in a self-administration protocol. Rats self-administered nicotine and cytisine during alternating four day periods, and changes in body weight, drug infusions, and meal patterns were compared between drugs and during an extinction phase. RESULTS In the first experiment, cytisine-treated rats ate less and gained less weight than those that received the vehicle. This occurred primarily by a reduced frequency of meals. In the 12 day post-cytisine phase, animals maintained a lower body weight relative to controls throughout. In the second experiment, total pellet intake increased during cytisine substitution relative to nicotine and animals self-administered cytisine significantly less than nicotine. However, cytisine substitution maintained decreases in food intake and weight gain compared to baseline via decreases in total pellet intake and meal size. CONCLUSION Cytisine administration results in decreased weight gain and changes in meal patterns dependent upon mode and pattern of administration and a previous history of nicotine administration.
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