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Akinola LS, Bagdas D, Alkhlaif Y, Jackson A, Gurdap CO, Rahimpour E, Carroll FI, Papke RL, Damaj MI. Pharmacological characterization of 5-iodo-A-85380, a β2-selective nicotinic receptor agonist, in mice. J Psychopharmacol 2022; 36:1280-1293. [PMID: 36321267 PMCID: PMC9817006 DOI: 10.1177/02698811221132214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Because of their implications in several pathological conditions, α4β2* nicotinic acetylcholine receptors (nAChRs) are potential targets for the treatment of nicotine dependence, pain, and many psychiatric and neurodegenerative diseases. However, they exist in various subtypes, and finding selective tools to investigate them has proved challenging. The nicotinic receptor agonist, 5-iodo-A-85380 (5IA), has helped in delineating the function of β2-containing subtypes in vitro; however, much is still unknown about its behavioral effects. Furthermore, its effectiveness on α6-containing subtypes is limited. AIMS To investigate the effects of 5IA on nociception (formalin, hot-plate, and tail-flick tests), locomotion, hypothermia, and conditioned reward after acute and repeated administration, and to examine the potential role of β2 and α6 nAChR subunits in these effects. Lastly, its selectivity for expressed low sensitivity (LS) and high sensitivity (HS) α4β2 receptors is investigated. RESULTS 5IA dose-dependently induced hypothermia, locomotion suppression, conditioned place preference, and antinociception (only in the formalin test but not in the hot-plate or tail-flick tests). Furthermore, these effects were mediated by β2 but not α6 nicotinic subunits. Finally, we show that 5-iodo-A-85380 potently activates both stoichiometries of α4β2 nAChRs with differential efficacies, being a full agonist on HS α4(2)β2(3) nAChRs, and a partial agonist on LS α4(3)β2(2) nAChRs and α6-containing subtypes as well.
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Affiliation(s)
- Lois S Akinola
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
| | - Deniz Bagdas
- Department of Psychiatry, School of Medicine, Yale University, USA
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - Yasmin Alkhlaif
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
| | - Asti Jackson
- Department of Psychiatry, School of Medicine, Yale University, USA
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - Cenk O Gurdap
- Science for Life Laboratory, Department of Women’s and Children’s Health, Karolinska Institutet, Sweden
| | - Elnaz Rahimpour
- Yale Tobacco Center of Regulatory Science, Yale University, USA
| | - F Ivy Carroll
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, USA
| | - Roger L Papke
- Department of Pharmacology and Therapeutics, University of Florida, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, USA
- Translational Research Initiative for Pain and Neuropathy, Medical College of Virginia Campus, Virginia Commonwealth University, USA
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Nicotinic Acetylcholine Receptors and Microglia as Therapeutic and Imaging Targets in Alzheimer's Disease. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092780. [PMID: 35566132 PMCID: PMC9102429 DOI: 10.3390/molecules27092780] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 12/12/2022]
Abstract
Amyloid-β (Aβ) accumulation and tauopathy are considered the pathological hallmarks of Alzheimer’s disease (AD), but attenuation in choline signaling, including decreased nicotinic acetylcholine receptors (nAChRs), is evident in the early phase of AD. Currently, there are no drugs that can suppress the progression of AD due to a limited understanding of AD pathophysiology. For this, diagnostic methods that can assess disease progression non-invasively before the onset of AD symptoms are essential, and it would be valuable to incorporate the concept of neurotheranostics, which simultaneously enables diagnosis and treatment. The neuroprotective pathways activated by nAChRs are attractive targets as these receptors may regulate microglial-mediated neuroinflammation. Microglia exhibit both pro- and anti-inflammatory functions that could be modulated to mitigate AD pathogenesis. Currently, single-cell analysis is identifying microglial subpopulations that may have specific functions in different stages of AD pathologies. Thus, the ability to image nAChRs and microglia in AD according to the stage of the disease in the living brain may lead to the development of new diagnostic and therapeutic methods. In this review, we summarize and discuss the recent findings on the nAChRs and microglia, as well as their methods for live imaging in the context of diagnosis, prophylaxis, and therapy for AD.
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Beaurain M, Salabert AS, Ribeiro MJ, Arlicot N, Damier P, Le Jeune F, Demonet JF, Payoux P. Innovative Molecular Imaging for Clinical Research, Therapeutic Stratification, and Nosography in Neuroscience. Front Med (Lausanne) 2019; 6:268. [PMID: 31828073 PMCID: PMC6890558 DOI: 10.3389/fmed.2019.00268] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 11/01/2019] [Indexed: 01/06/2023] Open
Abstract
Over the past few decades, several radiotracers have been developed for neuroimaging applications, especially in PET. Because of their low steric hindrance, PET radionuclides can be used to label molecules that are small enough to cross the blood brain barrier, without modifying their biological properties. As the use of 11C is limited by its short physical half-life (20 min), there has been an increasing focus on developing tracers labeled with 18F for clinical use. The first such tracers allowed cerebral blood flow and glucose metabolism to be measured, and the development of molecular imaging has since enabled to focus more closely on specific targets such as receptors, neurotransmitter transporters, and other proteins. Hence, PET and SPECT biomarkers have become indispensable for innovative clinical research. Currently, the treatment options for a number of pathologies, notably neurodegenerative diseases, remain only supportive and symptomatic. Treatments that slow down or reverse disease progression are therefore the subject of numerous studies, in which molecular imaging is proving to be a powerful tool. PET and SPECT biomarkers already make it possible to diagnose several neurological diseases in vivo and at preclinical stages, yielding topographic, and quantitative data about the target. As a result, they can be used for assessing patients' eligibility for new treatments, or for treatment follow-up. The aim of the present review was to map major innovative radiotracers used in neuroscience, and explain their contribution to clinical research. We categorized them according to their target: dopaminergic, cholinergic or serotoninergic systems, β-amyloid plaques, tau protein, neuroinflammation, glutamate or GABA receptors, or α-synuclein. Most neurological disorders, and indeed mental disorders, involve the dysfunction of one or more of these targets. Combinations of molecular imaging biomarkers can afford us a better understanding of the mechanisms underlying disease development over time, and contribute to early detection/screening, diagnosis, therapy delivery/monitoring, and treatment follow-up in both research and clinical settings.
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Affiliation(s)
- Marie Beaurain
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Anne-Sophie Salabert
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Maria Joao Ribeiro
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Nicolas Arlicot
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Philippe Damier
- Inserm U913, Neurology Department, University Hospital, Nantes, France
| | | | - Jean-François Demonet
- Leenards Memory Centre, Department of Clinical Neuroscience, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Pierre Payoux
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
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Mori D, Kimura H, Kawashima H, Yagi Y, Arimitsu K, Ono M, Saji H. Development of 99mTc radiolabeled A85380 derivatives targeting cerebral nicotinic acetylcholine receptor: Novel radiopharmaceutical ligand 99mTc-A-YN-IDA-C4. Bioorg Med Chem 2019; 27:4200-4210. [PMID: 31401009 DOI: 10.1016/j.bmc.2019.07.053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/25/2019] [Accepted: 07/30/2019] [Indexed: 01/22/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that have been implicated in higher brain functions. To elucidate the functional mechanisms underlying nAChRs and contribute significantly to development of drugs targeting neurological and neuropsychiatric diseases, non-invasive nuclear medical imaging can be used for evaluation. In addition, technetium-99m (99mTc) is a versatile radionuclide used clinically as a tracer in single-photon emission computed tomography. Because A85380 is known as a potent α4β2-nAChR agonist, we prepared A85380 derivatives labeled with 99mTc using a bifunctional chelate system. A computational scientific approach was used to design the probe efficiently. We used non-radioactive rhenium (Re) for a 99mTc analog and found that one of the derivatives, Re-A-YN-IDA-C4, exhibited high binding affinity at α4β2-nAChR in both the docking simulation (-19.3 kcal/mol) and binding assay (Ki = 0.4 ± 0.04 nM). Further, 99mTc-A-YN-IDA-C4 was synthesized using microwaves, and its properties were examined. Consequently, we found that 99mTc-A-YN-IDA-C4, with a structure optimized by using computational chemistry techniques, maintained affinity and selectivity for nAChR in vitro and possessed efficient characteristics as a nuclear medicine molecular imaging probe, demonstrated usefulness of computational scientific approach for molecular improvement strategy.
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Affiliation(s)
- Daisuke Mori
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hiroyuki Kimura
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan.
| | - Hidekazu Kawashima
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Radioisotope Research Center, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Yusuke Yagi
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Kenji Arimitsu
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Masahiro Ono
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hideo Saji
- Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
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Synthesis and biological evaluation of Tc-99m-cyclopentadienyltricarbonyl-technetium-labeled A-85380: An imaging probe for single-photon emission computed tomography investigation of nicotinic acetylcholine receptors in the brain. Bioorg Med Chem 2019; 27:2245-2252. [PMID: 31047775 DOI: 10.1016/j.bmc.2019.04.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/23/2019] [Accepted: 04/25/2019] [Indexed: 10/27/2022]
Abstract
We have designed (S)-(5-(azetidin-2-ylmethoxy)pyridine-3-yl)methyl cyclopentadienyltricarbonyl technetium carboxylate ([99mTc]CPTT-A-E) with high affinity for nicotinic acetylcholine receptors (nAChRs) using (2(S)-azetidinylmethoxy)-pyridine (A-85380) as the lead compound to develop a Tc-99m-cyclopentadienyltricarbonyl-technetium (99mTc)-labeled nAChR imaging probe. Because technetium does not contain a stable isotope, cyclopentadienyltricarbonyl rhenium (CPTR) was synthesized by coordinating rhenium, which is a homologous element having the same coordination structure as technetium. Further, the binding affinity to nAChR was evaluated. CPTR-A-E exhibited a high binding affinity to nAChR (Ki = 0.55 nM). Through the radiosynthesis of [99mTc]CPTT-A-E, an objective compound could be obtained with a radiochemical yield of 33% and a radiochemical purity of greater than 97%. In vitro autoradiographic study of the brain exhibited that the local nAChR density strongly correlated with the amount of [99mTc]CPTT-A-E that was accumulated in each region of interest. Further, the in vivo evaluation of biodistribution revealed a higher accumulation of [99mTc]CPTT-A-E in the thalamus (characterized by the high nAChR density) when compared with that in the cerebellum (characterized by the low nAChR density). Although additional studies will be necessary to improve the uptake of [99mTc]CPTT-A-E to the brain, [99mTc]CPTT-A-E met the basic requirements for nAChR imaging.
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Sultzer DL, Melrose RJ, Riskin-Jones H, Narvaez TA, Veliz J, Ando TK, Juarez KO, Harwood DG, Brody AL, Mandelkern MA. Cholinergic Receptor Binding in Alzheimer Disease and Healthy Aging: Assessment In Vivo with Positron Emission Tomography Imaging. Am J Geriatr Psychiatry 2017; 25:342-353. [PMID: 28162919 DOI: 10.1016/j.jagp.2016.11.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To compare regional nicotinic cholinergic receptor binding in older adults with Alzheimer disease (AD) and healthy older adults in vivo and to assess relationships between receptor binding and clinical symptoms. METHODS Using cross-sectional positron emission tomography (PET) neuroimaging and structured clinical assessment, outpatients with mild to moderate AD (N = 24) and healthy older adults without cognitive complaints (C group; N = 22) were studied. PET imaging of α4β2* nicotinic cholinergic receptor binding using 2-[18F]fluoro-3-(2(S)azetidinylmethoxy)pyridine (2FA) and clinical measures of global cognition, attention/processing speed, verbal memory, visuospatial memory, and neuropsychiatric symptoms were used. RESULTS 2FA binding was lower in the AD group compared with the C group in the medial thalamus, medial temporal cortex, anterior cingulate, insula/opercula, inferior caudate, and brainstem (p < 0.05, corrected cluster), but binding was not associated with cognition. The C group had significant inverse correlations between 2FA binding in the thalamus (left: rs = -0.55, p = 0.008; right: rs = -0.50, p = 0.02; N = 22) and hippocampus (left: rs = -0.65, p = 0.001; right: rs = -0.55, p = 0.009; N = 22) and the Trails A score. The AD group had inverse correlation between 2FA binding in anterior cingulate (left: rs = -0.50, p = 0.01; right: rs = -0.50, p = 0.01; N = 24) and Neurobehavioral Rating Scale agitation/disinhibition factor score. CONCLUSION Cholinergic receptor binding is reduced in specific brain regions in mild to moderate AD and is related to neuropsychiatric symptoms. Among healthy older adults, lower receptor binding may be associated with slower processing speed. Cholinergic receptor binding in vivo may reveal links to other key brain changes associated with aging and AD and may provide a potential molecular treatment target.
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Affiliation(s)
- David L Sultzer
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA.
| | - Rebecca J Melrose
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Hannah Riskin-Jones
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Theresa A Narvaez
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Joseph Veliz
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Timothy K Ando
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Kevin O Juarez
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Dylan G Harwood
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Arthur L Brody
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Mark A Mandelkern
- Imaging Service, VA Greater Los Angeles Healthcare Center, Los Angeles, CA; Department of Physics, University of California-Irvine, Irvine, CA
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Nicotinic acetylcholine receptor availability in cigarette smokers: effect of heavy caffeine or marijuana use. Psychopharmacology (Berl) 2016; 233:3249-57. [PMID: 27370018 PMCID: PMC4982797 DOI: 10.1007/s00213-016-4367-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/16/2016] [Indexed: 12/26/2022]
Abstract
RATIONALE Upregulation of α4β2* nicotinic acetylcholine receptors (nAChRs) is one of the most well-established effects of chronic cigarette smoking on the brain. Prior research by our group gave a preliminary indication that cigarette smokers with concomitant use of caffeine or marijuana have altered nAChR availability. OBJECTIVE We sought to determine if smokers with heavy caffeine or marijuana use have different levels of α4β2* nAChRs than smokers without these drug usages. METHODS One hundred and one positron emission tomography (PET) scans, using the radiotracer 2-FA (a ligand for β2*-containing nAChRs), were obtained from four groups of males: non-smokers without heavy caffeine or marijuana use, smokers without heavy caffeine or marijuana use, smokers with heavy caffeine use (mean four coffee cups per day), and smokers with heavy marijuana use (mean 22 days of use per month). Total distribution volume (Vt/fp) was determined for the brainstem, prefrontal cortex, and thalamus, as a measure of nAChR availability. RESULTS A significant between-group effect was found, resulting from the heavy caffeine and marijuana groups having the highest Vt/fp values (especially for the brainstem and prefrontal cortex), followed by smokers without such use, followed by non-smokers. Direct between-group comparisons revealed significant differences for Vt/fp values between the smoker groups with and without heavy caffeine or marijuana use. CONCLUSIONS Smokers with heavy caffeine or marijuana use have higher α4β2* nAChR availability than smokers without these drug usages. These findings are likely due to increased nicotine exposure but could also be due to an interaction on a cellular/molecular level.
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Ogunjirin AE, Fortunak JM, Brown LL, Xiao Y, Dávila-García MI. Competition, Selectivity and Efficacy of Analogs of A-84543 for Nicotinic Acetylcholine Receptors with Repositioning of Pyridine Nitrogen. Neurochem Res 2015; 40:2131-42. [PMID: 26508288 PMCID: PMC4741274 DOI: 10.1007/s11064-015-1705-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/13/2015] [Accepted: 08/18/2015] [Indexed: 01/17/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) play a crucial role in a number of clinically relevant mental and neurological pathways, as well as autonomic and immune functions. The development of subtype-selective ligands for nAChRs therefore is potentially useful for targeted therapeutic management of conditions where nAChRs are involved. We tested if selectivity for a particular nAChR subtype can be achieved through small structural modifications of a lead compound containing the nicotinic pharmacophore by changing the distance between the electronegative elements. For this purpose, analogs of A-84543 were designed, synthesized and characterized as potentially new nAChR subtype-selective ligands. Compounds were tested for their binding properties in rat cerebral cortical tissue homogenates, and subtype-selectivity was determined using stably transfected HEK cells expressing different nAChR subtypes. All compounds synthesized were found to competitively displace [(3)H]-epibatidine ([(3)H]EB) from the nAChR binding site. Of all the analogues, H-11MNH showed highest affinity for nAChRs compared to a ~ fivefold to tenfold lower affinity of A-84543. All other compounds had affinities >10,000 nM. Both A-84543 and H-11MNH have highest affinity for α2β2 and α4β2 nAChRs and show moderate affinity for β4- and α7-containing receptors. H-11MNH was found to be a full agonist with high potency at α3β4, while A-84543 is a partial agonist with low potency. Based on their unique pharmacological binding properties we suggest that A-84543 and its desmethylpyrrolidine analog can be useful as pharmacological ligands for studying nAChRs if selective pharmacological and/or genetic tools are used to mask the function of other receptors subtypes.
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Affiliation(s)
- Adebowale E Ogunjirin
- Department of Pharmaceutical Sciences, Howard University, Washington, DC, 20059, USA
| | - Joseph M Fortunak
- Department of Pharmaceutical Sciences, Howard University, Washington, DC, 20059, USA
- Department of Chemistry, Howard University, Washington, DC, 20059, USA
| | - LaVerne L Brown
- Department of Pharmaceutical Sciences, Howard University, Washington, DC, 20059, USA
| | - Yingxian Xiao
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, 20057, USA
| | - Martha I Dávila-García
- Department of Pharmacology, Howard University College of Medicine, Washington, DC, 20059, USA.
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Jasinska AJ, Zorick T, Brody AL, Stein EA. Dual role of nicotine in addiction and cognition: a review of neuroimaging studies in humans. Neuropharmacology 2014; 84:111-22. [PMID: 23474015 PMCID: PMC3710300 DOI: 10.1016/j.neuropharm.2013.02.015] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 12/28/2012] [Accepted: 02/19/2013] [Indexed: 12/11/2022]
Abstract
Substantial evidence demonstrates both nicotine's addiction liability and its cognition-enhancing effects. However, the neurobiological mechanisms underlying nicotine's impact on brain function and behavior remain incompletely understood. Elucidation of these mechanisms is of high clinical importance and may lead to improved therapeutics for smoking cessation as well as for a number of cognitive disorders such as schizophrenia. Neuroimaging techniques such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI), which make it possible to study the actions of nicotine in the human brain in vivo, play an increasingly important role in identifying these dual mechanisms of action. In this review, we summarize the current state of knowledge and discuss outstanding questions and future directions in human neuroimaging research on nicotine and tobacco. This research spans from receptor-level PET and SPECT studies demonstrating nicotine occupancy at nicotinic acetylcholine receptors (nAChRs) and upregulation of nAChRs induced by chronic smoking; through nicotine's interactions with the mesocorticolimbic dopamine system believed to mediate nicotine's reinforcing effects leading to dependence; to functional activity and connectivity fMRI studies documenting nicotine's complex behavioral and cognitive effects manifest by its actions on large-scale brain networks engaged both during task performance and at rest. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.
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Affiliation(s)
- Agnes J Jasinska
- National Institute on Drug Abuse, Intramural Research Program, 251 Bayview Blvd, Baltimore, MD 21224, United States.
| | - Todd Zorick
- University of California at Los Angeles, Department of Psychiatry, 300 UCLA Medical Plaza, Los Angeles, CA 90095, United States; VA Greater Los Angeles Healthcare System, United States
| | - Arthur L Brody
- University of California at Los Angeles, Department of Psychiatry, 300 UCLA Medical Plaza, Los Angeles, CA 90095, United States; VA Greater Los Angeles Healthcare System, United States.
| | - Elliot A Stein
- National Institute on Drug Abuse, Intramural Research Program, 251 Bayview Blvd, Baltimore, MD 21224, United States.
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Gallezot JD, Esterlis I, Bois F, Zheng MQ, Lin SF, Kloczynski T, Krystal JH, Huang Y, Sabri O, Carson RE, Cosgrove KP. Evaluation of the sensitivity of the novel α4β2* nicotinic acetylcholine receptor PET radioligand 18F-(-)-NCFHEB to increases in synaptic acetylcholine levels in rhesus monkeys. Synapse 2014; 68:556-64. [PMID: 25043426 DOI: 10.1002/syn.21767] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 06/30/2014] [Accepted: 07/01/2014] [Indexed: 12/29/2022]
Abstract
OBJECTIVE 18F-(-)-NCFHEB (also known as 18F-(-)-Flubatine) is a new radioligand to image α4β2* nicotinic acetylcholine receptors in vivo with positron emission tomography (PET), with faster kinetics than previous radioligands such as 18F-2-F-A85380. The goal of this study was to assess the sensitivity of 18F-(-)-NCFHEB-PET to increases in synaptic acetylcholine concentration induced by acetylcholinesterase inhibitors. METHODS Two rhesus monkeys were scanned four times each on a Focus 220 scanner: first at baseline, then during two bolus plus infusions of physostigmine (0.06-0.28 mg/kg), and finally following a bolus injection of donepezil (0.25 mg/kg). The arterial input function and the plasma free fraction fP were measured. 18F-(-)-NCFHEB volume of distribution VT was estimated using the multilinear analysis MA1 and then normalized by plasma free fraction fP . RESULTS 18F-(-)-NCFHEB fP was 0.89±0.04. At baseline, 18F-(-)-NCFHEB VT /fP ranged from 7.9±1.3 mL plasma/cm3 tissue in the cerebellum to 34.3±8.4 mL plasma/cm3 tissue in the thalamus. Physostigmine induced a dose-dependent reduction of 18F-(-)-NCFHEB VT /fP of 34±9% in the putamen, 32±8% in the thalamus, 25±8% in the cortex, and 23±10% in the hippocampus. With donepezil, 18F-(-)-NCFHEB VT /fP was reduced by 24±2%, 14+3% and 14±5%, 10±6% in the same regions. CONCLUSION 18F-(-)-NCFHEB can be used to detect changes in synaptic acetylcholine concentration and is a promising tracer to study acetylcholine dynamics with shorter scan durations than previous radioligands.
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Yu LF, Zhang HK, Caldarone BJ, Eaton JB, Lukas RJ, Kozikowski AP. Recent developments in novel antidepressants targeting α4β2-nicotinic acetylcholine receptors. J Med Chem 2014; 57:8204-23. [PMID: 24901260 PMCID: PMC4207546 DOI: 10.1021/jm401937a] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
![]()
Nicotinic acetylcholine receptors
(nAChRs) have been investigated
for developing drugs that can potentially treat various central nervous
system disorders. Considerable evidence supports the hypothesis that
modulation of the cholinergic system through activation and/or desensitization/inactivation
of nAChR holds promise for the development of new antidepressants.
The introductory portion of this Miniperspective discusses the basic
pharmacology that underpins the involvement of α4β2-nAChRs
in depression, along with the structural features that are essential
to ligand recognition by the α4β2-nAChRs. The remainder
of this Miniperspective analyzes reported nicotinic ligands in terms
of drug design considerations and their potency and selectivity, with
a particular focus on compounds exhibiting antidepressant-like effects
in preclinical or clinical studies. This Miniperspective aims to provide
an in-depth analysis of the potential for using nicotinic ligands
in the treatment of depression, which may hold some promise in addressing
an unmet clinical need by providing relief from depressive symptoms
in refractory patients.
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Affiliation(s)
- Li-Fang Yu
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago , 833 South Wood Street, Chicago, Illinois 60612, United States
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Simmons SJ, Gould TJ. Involvement of neuronal β2 subunit-containing nicotinic acetylcholine receptors in nicotine reward and withdrawal: implications for pharmacotherapies. J Clin Pharm Ther 2014; 39:457-67. [PMID: 24828779 DOI: 10.1111/jcpt.12171] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/14/2014] [Indexed: 11/28/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Tobacco smoking remains a major health problem. Nicotine binds to nicotinic acetylcholine receptors (nAChRs), which can cause addiction and withdrawal symptoms upon cessation of nicotine administration. Pharmacotherapies for nicotine addiction target brain alterations that underlie withdrawal symptoms. This review will delineate the involvement of the β2 subunit of neuronal nAChRs in nicotine reward and in generating withdrawal symptoms to better understand the efficacy of smoking cessation pharmacotherapies. COMMENT Chronic nicotine desensitizes and upregulates β2 subunit-containing nAChRs, and the prolonged upregulation of receptors may underlie symptoms of withdrawal. Experimental research has demonstrated that the β2 subunit of neuronal nAChRs is necessary for generating nicotine reward and withdrawal symptoms. WHAT IS NEW AND CONCLUSION Smoking cessation pharmacotherapies act on β2 subunit-containing nAChRs to reduce nicotine reward and withdrawal symptom severity.
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Affiliation(s)
- Steven J Simmons
- Department of Psychology, Neuroscience Program, Temple University, Philadelphia, PA, 19122, USA
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Cant AA, Champion S, Bhalla R, Pimlott SL, Sutherland A. Nickel-Mediated Radioiodination of Aryl and Heteroaryl Bromides: Rapid Synthesis of Tracers for SPECT Imaging. Angew Chem Int Ed Engl 2013; 52:7829-32. [DOI: 10.1002/anie.201302800] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 04/30/2013] [Indexed: 11/11/2022]
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14
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Cant AA, Champion S, Bhalla R, Pimlott SL, Sutherland A. Nickel-Mediated Radioiodination of Aryl and Heteroaryl Bromides: Rapid Synthesis of Tracers for SPECT Imaging. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302800] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Liu Y, Yu H, Zhao L, Zhang H. Design and synthesis of new agents for neuronal nicotinic acetylcholine receptor (nAChRs) imaging. Nucl Med Biol 2013; 40:126-34. [DOI: 10.1016/j.nucmedbio.2012.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 08/29/2012] [Accepted: 09/10/2012] [Indexed: 11/25/2022]
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Bagal SK, Brown AD, Cox PJ, Omoto K, Owen RM, Pryde DC, Sidders B, Skerratt SE, Stevens EB, Storer RI, Swain NA. Ion Channels as Therapeutic Targets: A Drug Discovery Perspective. J Med Chem 2012; 56:593-624. [DOI: 10.1021/jm3011433] [Citation(s) in RCA: 198] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sharan K. Bagal
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Alan D. Brown
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Peter J. Cox
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - Kiyoyuki Omoto
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Robert M. Owen
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - David C. Pryde
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Benjamin Sidders
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - Sarah E. Skerratt
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Edward B. Stevens
- Pfizer Neusentis, The
Portway Building, Granta Park, Great Abington, Cambridge, CB21
6GS, U.K
| | - R. Ian Storer
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
| | - Nigel A. Swain
- Worldwide Medicinal Chemistry, Pfizer Neusentis, The Portway Building, Granta Park,
Great Abington, Cambridge, CB21 6GS, U.K
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Pichika R, Kuruvilla SA, Patel N, Vu K, Sinha S, Easwaramoorthy B, Narayanan TK, Shi B, Christian B, Mukherjee J. Nicotinic α4β2 receptor imaging agents. Part IV. Synthesis and biological evaluation of 3-(2-(S)-3,4-dehydropyrrolinyl methoxy)-5-(3'-¹⁸F-fluoropropyl)pyridine (¹⁸F-Nifrolene) using PET. Nucl Med Biol 2012; 40:117-25. [PMID: 23141552 DOI: 10.1016/j.nucmedbio.2012.09.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 08/17/2012] [Accepted: 09/10/2012] [Indexed: 12/12/2022]
Abstract
Imaging agents for nicotinic α4β2 receptors in the brain have been under way for studying various CNS disorders. Previous studies from our laboratories have reported the successful development of agonist, ¹⁸F-nifene. In attempts to develop potential antagonists, ¹⁸F-nifrolidine and ¹⁸F-nifzetidine were previously reported. Further optimization of these fluoropropyl derivatives has now been carried out resulting in 3-(2-(S)-3,4-dehydropyrrolinylmethoxy)-5-(3'-Fluoropropyl)pyridine (nifrolene) as a new high affinity agent for nicotinic α4β2 receptors. Nifrolene in rat brain homogenate assays--labeled with ³H-cytisine--exhibited a binding affinity of 0.36 nM. The fluorine-18 analog, ¹⁸F-nifrolene, was synthesized in approximately 10%-20% yield and specific activity was estimated to be >2000 Ci/mmol. Rat brain slices indicated selective binding to anterior thalamic nuclei, thalamus, subiculum, striata, cortex and other regions consistent with α4β2 receptor distribution. This selective binding was displaced >90% by 300 μM nicotine. Thalamus to cerebellum ratio (>10) was the highest for ¹⁸F-nifrolene with several other regions showing selective binding. In vivo rat PET studies exhibited rapid uptake of ¹⁸F-nifrolene in the brain with specific retention in the thalamus and other brain regions while clearing out from the cerebellum. Thalamus to cerebellum ratio value in the rat was >4. Administration of nicotine caused a rapid decline in the thalamic ¹⁸F-nifrolene suggesting reversible binding to nicotinic receptors. PET imaging studies of ¹⁸F-nifrolene in anesthetized rhesus monkey revealed highest binding in the thalamus followed by regions of the lateral cingulated and temporal cortex. Cerebellum showed the least binding. Thalamus to cerebellum ratio in the monkey brain was >3 at 120 min. These ratios of ¹⁸F-nifrolene are higher than measured for ¹⁸F-nifrolidine and ¹⁸F-nifzetidine. ¹⁸F-Nifrolene thus shows promise as a new PET imaging agent for α4β2 nAChR.
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Affiliation(s)
- Rama Pichika
- Preclinical Imaging, Department of Radiological Sciences, University of California, Irvine, CA 92697, USA
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Halldin C, Dollé F, Hall H, Varnäs K, Sandell J, Demphel S, Crouzel C. Development of a central nicotinic acetylcholine receptor radioligand, 5-methyl-A-85380, and postmortem autoradiography in human brain. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.2580440188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Koren AO, Chefer SI, Mukhin AG, Pavlova OA, Horti AG, Vaupel DB, London ED, Kimes AS. 5-IODO-6-[18F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine, a novel pet radioligand for nicotinic acetylcholine receptors: Synthesis and initial evaluation. J Labelled Comp Radiopharm 2012. [DOI: 10.1002/jlcr.2580440190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Yu LF, Tückmantel W, Eaton JB, Caldarone B, Fedolak A, Hanania T, Brunner D, Lukas RJ, Kozikowski AP. Identification of novel α4β2-nicotinic acetylcholine receptor (nAChR) agonists based on an isoxazole ether scaffold that demonstrate antidepressant-like activity. J Med Chem 2012; 55:812-23. [PMID: 22148173 DOI: 10.1021/jm201301h] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
There is considerable evidence to support the hypothesis that the blockade of nAChR is responsible for the antidepressant action of nicotinic ligands. The nicotinic acetylcholine receptor (nAChR) antagonist, mecamylamine, has been shown to be an effective add-on in patients that do not respond to selective serotonin reuptake inhibitors. This suggests that nAChR ligands may address an unmet clinical need by providing relief from depressive symptoms in refractory patients. In this study, a new series of nAChR ligands based on an isoxazole-ether scaffold have been designed and synthesized for binding and functional assays. Preliminary structure-activity relationship (SAR) efforts identified a lead compound 43, which possesses potent antidepressant-like activity (1 mg/kg, IP; 5 mg/kg, PO) in the classical mouse forced swim test. Early stage absorption, distribution, metabolism, excretion, and toxicity (ADME-Tox) studies also suggested favorable drug-like properties, and broad screening toward other common neurotransmitter receptors indicated that compound 43 is highly selective for nAChRs over the other 45 neurotransmitter receptors and transporters tested.
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Affiliation(s)
- Li-Fang Yu
- Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, United States
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Lotfipour S, Mandelkern M, Brody AL. Quantitative Molecular Imaging of Neuronal Nicotinic Acetylcholine Receptors in the Human Brain with A-85380 Radiotracers. Curr Med Imaging 2011; 7:107-112. [PMID: 22773924 DOI: 10.2174/157340511795445676] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChRs) have been implicated in a spectrum of cognitive functions as well as psychiatric and neurodegenerative disorders, including tobacco addiction and Alzheimer's Disease. The examination of neuronal nAChRs in living humans is a relatively new field. Researchers have developed brain-imaging radiotracers for nAChRs, with radiolabeled A-85380 compounds having the most widespread use. We provide a brief background on nAChRs, followed by a discussion of the development and application of A-85380 radiotracers in human imaging studies. We describe potential future studies using nicotinic receptor radioligands for the study of tobacco addiction, including the mechanism of action of the smoking-cessation therapy varenicline. Throughout this review, we focus on the significant potential that resides in the identification and quantification of nAChRs in the living human brain.
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Affiliation(s)
- Shahrdad Lotfipour
- Department of Psychiatry, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Chin CL, Carr RA, Llano DA, Barret O, Xu H, Batis J, Koren AO, Seibyl JP, Marsh KC, Tamagnan G, Decker MW, Day M, Fox GB. Pharmacokinetic Modeling and [123I]5-IA-85380 Single Photon Emission Computed Tomography Imaging in Baboons: Optimization of Dosing Regimen for ABT-089. J Pharmacol Exp Ther 2010; 336:716-23. [DOI: 10.1124/jpet.110.173609] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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Pimlott SL, Sutherland A. Molecular tracers for the PET and SPECT imaging of disease. Chem Soc Rev 2010; 40:149-62. [PMID: 20818455 DOI: 10.1039/b922628c] [Citation(s) in RCA: 227] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging continues to grow due to the ability of these techniques to allow the non-invasive in vivo visualisation of biological processes at the molecular and cellular levels. As well as finding application for the diagnosis of disease, these techniques have also been used in the drug discovery process. Crucial to the growth of these techniques is the continued development of molecular probes that can bind to the target biological receptor with high selectivity. This tutorial review describes the use of PET and SPECT for molecular imaging and highlights key strategies for the development of molecular probes for the imaging of both cancer and neurological diseases.
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Affiliation(s)
- Sally L Pimlott
- West of Scotland Radionuclide Dispensary, NHS Greater Glasgow and Clyde, Glasgow G11 6NT, UK
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24
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Esterlis I, Cosgrove KP, Batis JC, Bois F, Stiklus SM, Perkins E, Seibyl JP, Carson RE, Staley JK. Quantification of smoking-induced occupancy of beta2-nicotinic acetylcholine receptors: estimation of nondisplaceable binding. J Nucl Med 2010; 51:1226-33. [PMID: 20660383 DOI: 10.2967/jnumed.109.072447] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED 5-(123)I-iodo-85380 ((123)I-5-IA) is used to quantitate high-affinity nicotinic acetylcholine receptors (beta(2)-nAChRs) on human SPECT scans. The primary outcome measure is V(T)/f(P), the ratio at equilibrium between total tissue concentration (free, nonspecifically bound, and specifically bound) and the free plasma concentration. Nondisplaceable uptake (free plus nonspecific) of (123)I-5-IA has not been measured in human subjects. Nicotine has high affinity for beta(2)*-nAChRs (nAChRs containing the beta(2)* subunit, for which * represents other subunits that may also be part of the receptor) and displaces specifically bound (123)I-5-IA. In this study, we measured nicotine occupancy and nondisplaceable binding in healthy smokers after they had smoked to satiety. METHODS Eleven nicotine-dependent smokers (mean age +/- SD, 35.6 +/- 14.4 y) completed the study. One subject was excluded from subsequent analyses because of abnormal blood nicotine levels. Subjects abstained from tobacco smoke for 5.3 +/- 0.9 d and participated in a 15- to 17-h SPECT scanning day. (123)I-5-IA was administered by bolus plus constant infusion, with a total injected dose of 361 +/- 20 MBq. At approximately 6 h after the start of the infusion, three 30-min SPECT scans and a 15-min transmission-emission scan were acquired to obtain baseline beta(2)*-nAChR availability. Subjects then smoked to satiety (2.4 +/- 0.7 cigarettes), and arterial (first 40 min) and venous (until study completion) plasma nicotine and cotinine levels were collected. About 1 h after subjects had smoked to satiety, up to six 30-min SPECT scans were acquired. V(T)/f(P) data, computed from the tissue and plasma radioactivity measurements from the presmoking baseline and postsmoking scans, were analyzed using the Lassen plot method. RESULTS Receptor occupancy after subjects had smoked to satiety was 67% +/- 9% (range, 55%-80%). Nondisplaceable uptake was estimated as 19.4 +/- 5.8 mL x cm(-3) (range, 15-28 mL x cm(-3)). Thus, in the thalamus, where mean V(T)/f(P) is 93 mL x cm(-3), nondisplaceable binding represents approximately 20% of the total binding. CONCLUSION These results are in agreement with previous findings and suggest that when satiating doses of nicotine are administered to smokers, imaging of receptor availability can yield valuable data, such as quantifiable measures of nondisplaceable binding.
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Affiliation(s)
- Irina Esterlis
- Department of Psychiatry, Yale University School of Medicine and the Veteran's Affairs Connecticut Healthcare System, West Haven, Connecticut 06516, USA.
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Kawasaki Y, Chufan EE, Lafont V, Hidaka K, Kiso Y, Amzel LM, Freire E. How much binding affinity can be gained by filling a cavity? Chem Biol Drug Des 2010; 75:143-51. [PMID: 20028396 PMCID: PMC3209665 DOI: 10.1111/j.1747-0285.2009.00921.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Binding affinity optimization is critical during drug development. Here, we evaluate the thermodynamic consequences of filling a binding cavity with functionalities of increasing van der Waals radii (-H, -F, -Cl, and CH(3)) that improve the geometric fit without participating in hydrogen bonding or other specific interactions. We observe a binding affinity increase of two orders of magnitude. There appears to be three phases in the process. The first phase is associated with the formation of stable van der Waals interactions. This phase is characterized by a gain in binding enthalpy and a loss in binding entropy, attributed to a loss of conformational degrees of freedom. For the specific case presented in this article, the enthalpy gain amounts to -1.5 kcal/mol while the entropic losses amount to +0.9 kcal/mol resulting in a net 3.5-fold affinity gain. The second phase is characterized by simultaneous enthalpic and entropic gains. This phase improves the binding affinity 25-fold. The third phase represents the collapse of the trend and is triggered by the introduction of chemical functionalities larger than the binding cavity itself [CH(CH(3))(2)]. It is characterized by large enthalpy and affinity losses. The thermodynamic signatures associated with each phase provide guidelines for lead optimization.
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Affiliation(s)
- Yuko Kawasaki
- Department of Biology, Johns Hopkins University, Baltimore MD 21218
| | - Eduardo E. Chufan
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Virginie Lafont
- Department of Biology, Johns Hopkins University, Baltimore MD 21218
| | - Koushi Hidaka
- Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan
| | - Yoshiaki Kiso
- Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8412, Japan
| | - L. Mario Amzel
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ernesto Freire
- Department of Biology, Johns Hopkins University, Baltimore MD 21218
,Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
,Corresponding author: Department of Biology, The Johns Hopkins University, 3400 North Charles, Baltimore, MD 21218; Phone: (410) 516-7743, Fax: (410) 516-6469;
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Kas A, Bottlaender M, Gallezot JD, Vidailhet M, Villafane G, Grégoire MC, Coulon C, Valette H, Dollé F, Ribeiro MJ, Hantraye P, Remy P. Decrease of nicotinic receptors in the nigrostriatal system in Parkinson's disease. J Cereb Blood Flow Metab 2009; 29:1601-8. [PMID: 19491921 DOI: 10.1038/jcbfm.2009.74] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Smoking is associated with a lower incidence of Parkinson's disease (PD), which might be related to a neuroprotective action of nicotine. Postmortem studies have shown a decrease of cerebral nicotinic acetylcholine receptors (nAChRs) in PD. In this study, we evaluated the decrease of nAChRs in PD in vivo using positron emission tomography (PET), and we explored the relationship between nAChRs density and PD severity using both clinical scores and the measurement of striatal dopaminergic function. Thirteen nondemented patients with PD underwent two PET scans, one with 6-[(18)F]fluoro-3,4-dihydroxy-L-phenylalanine (6-[(18)F]fluoro-L-DOPA) to measure the dopaminergic function and another with 2-[(18)F]fluoro-3-[2(S)-2-azetidinylmethoxy]pyridine (2-[(18)F]fluoro-A-85380), a radiotracer with high affinity for the nAChRs. Distribution volumes (DVs) of 2-[(18)F]fluoro-A-85380 measured in the PD group were compared with those obtained from six nonsmoking healthy controls, with regions-of-interest and voxel-based approaches. Both analyses showed a significant (P <0.05) decrease of 2-[(18)F]fluoro-A-85380 DV in the striatum (-10%) and substantia nigra (-14.9%) in PD patients. Despite the wide range of PD stages, no correlation was found between DV and the clinical and PET markers of PD severity.
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Affiliation(s)
- Aurélie Kas
- URA CNRS-CEA 2210, MIRCen, I2BM/DSV, Orsay, France.
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Brain nicotinic acetylcholine receptor occupancy: effect of smoking a denicotinized cigarette. Int J Neuropsychopharmacol 2009; 12:305-16. [PMID: 18706128 PMCID: PMC2773668 DOI: 10.1017/s146114570800922x] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Our group recently reported that smoking a regular cigarette (1.2-1.4 mg nicotine) resulted in 88% occupancy of brain alpha4beta2* nicotinic acetylcholine receptors (nAChRs). However, this study did not determine whether nicotine inhalation or the many other pharmacological and behavioural factors that occur during smoking resulted in this receptor occupancy. If nicotine is solely responsible for alpha4beta2* nAChR occupancy from smoking, then (as estimated from our previous data) smoking a denicotinized (0.05 mg nicotine) or a low-nicotine (0.6 mg nicotine) cigarette (commonly used for research and clinical purposes) would result in substantial 23% and 78% alpha4beta2* nAChR occupancies, respectively, and a plasma nicotine concentration of 0.87 ng/ml would result in 50% alpha4beta2* nAChR occupancy (EC50). Twenty-four positron emission tomography sessions were performed on tobacco-dependent smokers, using 2-[F-18]fluoro-A-85380 (2-FA), a radiotracer that binds to alpha4beta2* nAChRs. 2-FA displacement was determined from before to 3.1 hours after either: no smoking, smoking a denicotinized cigarette, or smoking a low-nicotine cigarette. Analysis of this PET data revealed that smoking a denicotinized and a low-nicotine cigarette resulted in 26% and 79% alpha4beta2* nAChR occupancies, respectively, across three regions of interest. The EC50 determined from this dataset was 0.75 ng/ml. Given the consistency of findings between our previous study with regular cigarettes and the present study, nicotine inhalation during smoking appears to be solely responsible for alpha4beta2* nAChR occupancy, with other factors (if present at all) having either short-lived or very minor effects. Furthermore, smoking a denicotinized cigarette resulted in substantial nAChR occupancy.
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Brasić JR, Zhou Y, Musachio JL, Hilton J, Fan H, Crabb A, Endres CJ, Reinhardt MJ, Dogan AS, Alexander M, Rousset O, Maris MA, Galecki J, Nandi A, Wong DF. Single photon emission computed tomography experience with (S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine in the living human brain of smokers and nonsmokers. Synapse 2009; 63:339-58. [PMID: 19140167 PMCID: PMC2766259 DOI: 10.1002/syn.20611] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
(S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine (5-[(123)I]IA), a novel potent radioligand for high-affinity alpha4beta2* neuronal nicotinic acetylcholine receptors (nAChRs), provides a means to evaluate the density and the distribution of nAChRs in the living human brain. We sought in healthy adult smokers and nonsmokers to (1) evaluate the safety, tolerability, and efficacy of 5-[(123)I]IA in an open nonblind trial and (2) to estimate the density and the distribution of alpha(4)beta(2)* nAChRs in the brain. Single photon emission computed tomography (SPECT) was performed for 5 h after the i.v. administration of approximately 0.001 microg/kg ( approximately 10 mCi) 5-[(123)I]IA. Blood pressure, heart rate, and neurobehavioral status were monitored before, during, and after the administration of 5-[(123)I]IA to 12 healthy adults (8 men and 4 women) (6 smokers and 6 nonsmokers) ranging in age from 19 to 46 years (mean = 28.25, standard deviation = 8.20). High plasma-nicotine level was significantly associated with low 5-[(123)I]IA binding in: (1) the caudate head, the cerebellum, the cortex, and the putamen, utilizing both the Sign and Mann-Whitney U-tests; (2) the fusiform gyrus, the hippocampus, the parahippocampus, and the pons utilizing the Mann-Whitney U-test; and (3) the thalamus utilizing the Sign test. We conclude that 5-[(123)I]IA is a safe, well-tolerated, and effective pharmacologic agent for human subjects to estimate high-affinity alpha4/beta2 nAChRs in the living human brain.
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Affiliation(s)
- James Robert Brasić
- Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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Abstract
While most cigarette smokers endorse a desire to quit smoking, only 14-49% will achieve abstinence after 6 months or more of treatment. A greater understanding of the effects of smoking on brain function may result in improved pharmacological and behavioral interventions for this condition. Research groups have examined the effects of acute and chronic nicotine/cigarette exposure on brain activity using functional imaging; the purpose of this chapter is to synthesize findings from such studies and present a coherent model of brain function in smokers. Responses to acute administration of nicotine/smoking include reduced global brain activity; activation of the prefrontal cortex, thalamus, and visual system; activation of the thalamus and visual cortex during visual cognitive tasks; and increased dopamine (DA) concentration in the ventral striatum/nucleus accumbens. Responses to chronic nicotine/cigarette exposure include decreased monoamine oxidase (MAO) A and B activity in the basal ganglia and a reduction in alpha4beta2 nicotinic acetylcholine receptor (nAChR) availability in the thalamus and putamen (accompanied by an overall upregulation of these receptors). These findings indicate that smoking enhances neurotransmission through cortico-basal ganglia-thalamic circuits by direct stimulation of nAChRs, indirect stimulation via DA release or MAO inhibition, or a combination of these and possibly other factors. Activation of this circuitry may be responsible for the effects of smoking seen in tobacco-dependent smokers, such as improvements in attentional performance, mood, anxiety, and irritability.
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Affiliation(s)
- Anil Sharma
- Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine, Greater Los Angeles VA Healthcare System, 11301 Wilshire Blvd. Bldg 256 Suite 221, Los Angeles, CA 90073, USA.
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Wildeboer KM, Stevens KE. Stimulation of the alpha4beta2 nicotinic receptor by 5-I A-85380 improves auditory gating in DBA/2 mice. Brain Res 2008; 1224:29-36. [PMID: 18582447 DOI: 10.1016/j.brainres.2008.06.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 11/17/2022]
Abstract
Abnormal auditory gating is a symptom of schizophrenia which has been proposed to be mediated through the alpha7 nicotinic acetylcholine receptor (nAChR). It has been shown that the non-selective nicotinic agonist nicotine has an influence on auditory gating in part by acting on the alpha4beta2 nAChR. The goal of this study was to determine the effect of 5-I A-85380, an agonist for the alpha4beta2 nAChR, in an inbred mouse model with a deficiency for auditory gating. Anesthetized DBA/2 mice were administered 5-I A-85380 alone and in combination with the alpha4beta2 nAChR antagonist, dihydro-beta-erythroidine, or the alpha7 nAChR antagonist, alpha-bungarotoxin. A recording electrode in the CA3 region of the hippocampus recorded P20-N40 waveforms in response to two auditory stimuli. The amplitudes of the response to the first and second clicks were used to determine TC ratios, the measure of auditory gating. 5-I A-85380 significantly decreased the TC ratios by selectively increasing the response amplitudes to the first click with no significant influence on the response amplitudes to the second click. The effect was blocked by dihydro-beta-erythroidine whereas alpha-bungarotoxin had no effect on response amplitude to either click. Although the alpha7 nAChR may mediate the hippocampal response of DBA/2 mice to the second click, the alpha4beta2 nAChR appears to modulate the response to the first click. Thus, the present study implicates the involvement of more than one subtype of nAChR in the auditory gating of DBA/2 mice, specifically the alpha4beta2 nAChR, and its role in the response amplitude to the first stimulus.
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Affiliation(s)
- Kristin M Wildeboer
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
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Affiliation(s)
- Simon M Ametamey
- Center for Radiopharmaceutical Science of ETH, PSI and USZ, Department of Chemistry and Applied Biosciences of ETH, CH-8093 Zurich, Switzerland.
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Gallezot JD, Bottlaender MA, Delforge J, Valette H, Saba W, Dollé F, Coulon CM, Ottaviani MP, Hinnen F, Syrota A, Grégoire MC. Quantification of cerebral nicotinic acetylcholine receptors by PET using 2-[18F]fluoro-A-85380 and the multiinjection approach. J Cereb Blood Flow Metab 2008; 28:172-89. [PMID: 17519978 DOI: 10.1038/sj.jcbfm.9600505] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The multiinjection approach was used to study in vivo interactions between alpha4beta2(*) nicotinic acetylcholine receptors and 2-[(18)F]fluoro-A-85380 in baboons. The ligand kinetics was modeled by the usual nonlinear compartment model composed of three compartments (arterial plasma, free and specifically bound ligand in tissue). Arterial blood samples were collected to generate a metabolite-corrected plasma input function. The experimental protocol, which consisted of three injections of labeled or unlabeled ligand, was aiming at identifying all parameters in one experiment. Various parameters, including B'(max) (the binding sites density) and K(d)V(R) (the apparent in vivo affinity of 2-[(18)F]fluoro-A-85380) could then be estimated in thalamus and in several receptor-poor regions. B'(max) estimate was 3.0+/-0.3 pmol/mL in thalamus, and ranged from 0.25 to 1.58 pmol/mL in extrathalamic regions. Although K(d)V(R) could be precisely estimated, the association and dissociation rate constants k(on)/V(R) and k(off) could not be identified separately. A second protocol was then used to estimate k(off) more precisely in the thalamus. Having estimated all model parameters, we performed simulations of 2-[(18)F]fluoro-A-85380 kinetics to test equilibrium hypotheses underlying simplified approaches. These showed that a pseudo-equilibrium is quickly reached between the free and bound compartments, a favorable situation to apply Logan graphical analysis. In contrast, the pseudo-equilibrium between the plasma and free compartments is only reached after several hours. The ratio of radioligand concentration in these two compartments then overestimates the true equilibrium value, an unfavorable situation to estimate distribution volumes from late images after a bolus injection.
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Valette H, Dollé F, Saba W, Roger G, Hinnen F, Coulon C, Ottaviani M, Syrota A, Bottlaender M. [18F]FPhEP and [18F]F2PhEP, two new epibatidine-based radioligands: evaluation for imaging nicotinic acetylcholine receptors in baboon brain. Synapse 2007; 61:764-70. [PMID: 17568410 DOI: 10.1002/syn.20426] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The radioligand 2-[(18)F]fluoro-A-85380 has been developed for imaging alpha(4)beta(2) nAChRs with PET. However, it has slow kinetics and a large fraction of bound activity is nondisplaceable. In an attempt to address these problems, two epibatidine-based alpha(4)beta(2) nicotinic antagonists, coded FPhEP and F(2)PhEP, were evaluated in vivo in baboons. They were radiolabeled with fluorine-18 from the corresponding N-Boc-protected bromo-derivatives and the no-carrier-added K[(18)F]F-Kryptofix(222) complex. Radiochemically pure [(18)F]FPhEP or [(18)F]F(2)PhEP was obtained in 80 min in amounts of 1.11-2.22 GBq (111-185 GBq/micromol). After injection of 215 MBq of [(18)F]FPhEP or [(18)F]F(2)PhEP, dynamic PET data were acquired. Thalamic radioactivity peaked at 20 min (4.9% +/- 0.2% ID/100 mL tissue) for [(18)F]FPhEP. For [(18)F]F(2)PhEP, the peak was at 45 min (3.3% +/- 0.1% ID/100 mL tissue). Regional distribution of both radiotracers was in accordance with the known distribution of nAChRs. In presaturation experiments, nicotine, cytosine, or FPhEP reduced brain radioactivity of [(18)F]FPhEP. In a displacement experiment with nicotine only a small amount of [(18)F]F(2)PhEP was dislodged. In spite of a moderate to high in vitro affinity, both ligands do not fulfill the widely adopted criteria for a PET radioligand.
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Affiliation(s)
- Héric Valette
- CEA, Institut d'Imagerie Biomédicale, Service Hospitalier Frédéric Joliot, 4 Place du Général Leclerc, F-91406 Orsay, France.
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Chefer SI, Pavlova OA, Zhang Y, Vaupel DB, Kimes AS, Horti AG, Stein E, Mukhin AG. NIDA522131, a new radioligand for imaging extrathalamic nicotinic acetylcholine receptors: in vitro and in vivo evaluation. J Neurochem 2007; 104:306-15. [PMID: 17986233 DOI: 10.1111/j.1471-4159.2007.05009.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel radioligand, 6-chloro-3-((2-(S)-azetidinyl)methoxy)-5-(2-fluoropyridin-4-yl)pyridine (NIDA522131), for imaging extrathalamic nicotinic acetylcholine receptors (nAChRs) was characterized in vitro and in vivo using positron emission tomography. The K(d) and T(1/2) of dissociation of NIDA522131 binding measured at 37 degrees C in vitro were 4.9 +/- 0.4 pmol/L and 81 +/- 5 min, respectively. The patterns of radioactivity distribution in monkey brain in vivo was similar to that of 2-[(18)F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2FA), a radioligand that has been successfully used in humans, and matched the alpha(4)beta(2)* nAChRs distribution. Comparison between [(18)F]NIDA522131 and 2FA demonstrated better in vivo binding properties of the new radioligand and substantially greater radioactivity accumulation in brain. Consistent with [(18)F]NIDA522131 elevated affinity for nAChRs and its increased lipophilicity, both, the total and non-displaceable distribution volumes were substantially higher than those of 2FA. Estimated binding potential values in different brain regions, characterizing the specificity of receptor binding, were 3-4 fold higher for [(18)F]NIDA522131 than those of 2FA. Pharmacological evaluation in mice demonstrated a toxicity that was comparable to 2FA and is in agreement with a 2300 fold higher affinity at alpha(4)beta(2)* versus alpha(3)beta(4)* nAChRs. These results suggest that [(18)F]NIDA522131 is a promising positron emission tomography radioligand for studying extrathalamic nAChR in humans.
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Affiliation(s)
- Svetlana I Chefer
- Neuroimaging Research Branch, Intramural Research Program, National Institute on Drug Abuse, National Institute of Health, Department of Health and Human Services, Baltimore, Maryland, USA
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Zaniewska M, McCreary AC, Przegaliński E, Filip M. Effects of the serotonin 5-HT2A and 5-HT2C receptor ligands on the discriminative stimulus effects of nicotine in rats. Eur J Pharmacol 2007; 571:156-65. [PMID: 17617403 DOI: 10.1016/j.ejphar.2007.05.067] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 05/25/2007] [Accepted: 05/30/2007] [Indexed: 11/29/2022]
Abstract
The present study tested the hypothesis that serotonergic (5-HT) 5-HT2A or 5-HT2C receptors or their pharmacological stimulation modulated the discriminative stimulus effects of nicotine in male Wistar rats. To this end the selective 5-HT2A receptor antagonist R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol (M100,907; 0.5-1 mg/kg, i.p.), the functional 5-HT2A receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI; 0.1-1 mg/kg, s.c.), the selective 5-HT2C receptor antagonist 6-chloro-5-methyl-1-{[2-(2-methylpyrid-3-yloxy)pyrid-5-yl]carbamoyl}indoline (SB 242,084; 0.25-1 mg/kg, i.p.) and the 5-HT2C receptor agonists (S)-2-chloro-5-fluoro-indol-1-yl)-1-methylethylamine fumarate (Ro 60-0175; 0.3-1 mg/kg, s.c.) and (7bR, 10aR)-1,2,3,4,8,9,10,10a-octahydro-7bH-cyclopenta-[b][1,4]diazepino[6,7,1hi]indole (WAY 163,909; 0.75-1.5 mg/kg, i.p.) were used. Additionally, the effects of the selective alpha4beta2 nicotinic acetylcholine receptor subtype agonist 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5-IA; 0.01 mg/kg, s.c.) were investigated. In rats trained to discriminate (-)-nicotine (0.4 mg/kg, s.c.) from saline in a two-lever, water-reinforced fixed ratio 10 task, substitutions were not observed with 5-HT2 receptor ligands (<32% nicotine-lever responding), conversely 5-IA induced a full substitution (100% nicotine-lever responding). In combination studies, fixed doses of M100,907 (0.5-1 mg/kg) or SB 242,084 (0.25-1 mg/kg) did not alter the dose-response curve of nicotine, while DOI (0.3 mg/kg), Ro 60-0175 (1 mg/kg) and WAY 163,909 (1 and 1.5 mg/kg) attenuated the discriminative stimulus effects of nicotine. The decrease in the expression of the discriminative stimulus effects of nicotine produced by DOI was blocked by M100,907 (1 mg/kg), but not by SB 242,084 (1 mg/kg), while that evoked by Ro 60-0175 or WAY 163,909 was blocked by SB 242,084 (1 mg/kg), but not by M100,907 (1 mg/kg). Further studies showed that DOI (0.3 mg/kg) and Ro 60-0175 (1 mg/kg), but not WAY 163,909 (1.5 mg/kg) blocked full substitution of 5-IA (0.01 mg/kg) for nicotine. Our pharmacological analyses indicate that tonic activation of 5-HT2A or 5-HT2C receptors is not required for subjective effects of nicotine, however these receptors appear to have inhibitory influence on nicotine cue, since pharmacological stimulation of either receptor attenuates the discriminative stimulus effects of nicotine.
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MESH Headings
- Aminopyridines/pharmacology
- Amphetamines/pharmacology
- Animals
- Azepines/pharmacology
- Azetidines/pharmacology
- Behavior, Animal/drug effects
- Brain/drug effects
- Brain/metabolism
- Discrimination, Psychological/drug effects
- Dose-Response Relationship, Drug
- Ethylamines/pharmacology
- Fluorobenzenes/pharmacology
- Indoles/pharmacology
- Ligands
- Male
- Nicotine/pharmacology
- Nicotinic Agonists/pharmacology
- Piperidines/pharmacology
- Pyridines/pharmacology
- Rats
- Rats, Wistar
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Nicotinic/drug effects
- Receptors, Nicotinic/metabolism
- Serotonin 5-HT2 Receptor Agonists
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
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Affiliation(s)
- Magdalena Zaniewska
- Laboratory of Drug Addiction Pharmacology, Department of Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, 31-343 Kraków, 12 Smetna, Poland
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Pogocki D, Ruman T, Danilczuk M, Danilczuk M, Celuch M, Wałajtys-Rode E. Application of nicotine enantiomers, derivatives and analogues in therapy of neurodegenerative disorders. Eur J Pharmacol 2007; 563:18-39. [PMID: 17376429 DOI: 10.1016/j.ejphar.2007.02.038] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 02/04/2007] [Accepted: 02/15/2007] [Indexed: 12/21/2022]
Abstract
This review gives a brief overview over the major aspects of application of the nicotine alkaloid and its close derivatives in the therapy of some neurodegenerative disorders and diseases (e.g. Alzheimer's disease, Parkinson's disease, Tourette's syndrome, schizophrenia etc.). The issues concerning methods of nicotine analysis and isolation, and some molecular aspects of nicotine pharmacology are included. The natural and synthetic analogues of nicotine that are considered for medical practice are also mentioned. The molecular properties of two naturally occurring nicotine enantiomers are compared--the less-common but less-toxic (R)-nicotine is suggested as a natural compound that may find its place in pharmaceutical practice.
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Affiliation(s)
- Dariusz Pogocki
- Rzeszów University of Technology, Faculty of Chemistry, Department of Biochemistry and Biotechnology, 6 Powstańców Warszawy Ave. 35-959 Rzeszów, Poland
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37
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Chan WK, Wong PTH, Sheu FS. Frontal cortical α7 and α4β2 nicotinic acetylcholine receptors in working and reference memory. Neuropharmacology 2007; 52:1641-9. [PMID: 17482650 DOI: 10.1016/j.neuropharm.2007.03.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 02/19/2007] [Accepted: 03/18/2007] [Indexed: 10/23/2022]
Abstract
The alpha7 and alpha4beta2 nicotinic acetylcholine receptor (nAchR) subtypes have been shown to be involved in memory. It is also known that losses of frontal cortical nAchRs are correlated to declining memory function in Alzheimer's disease, but the subtype-specific role of frontal cortical nAchRs in memory has not been well characterized. Hence, we sought to understand the role of frontal cortical alpha7 and alpha4beta2 nAchR subtypes in both working and reference memory by observing the effects of subtype specific agonists and antagonists on radial arm maze performance. It was found that alpha7 nAchRs in the frontal cortex are involved in working and reference memory, while alpha4beta2 nAchRs are only involved in working memory. Throughout the study, drug treatments did not affect motor functionality in the animals. Our data thus sheds further light on the frontal cortex as an important anatomical locus for nAchR-mediated memory function in the brain, and highlights the differing role of alpha7 and alpha4beta2 nAchRs in long and short term memory.
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Affiliation(s)
- Wai Kit Chan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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Carreras J, Avenoza A, Busto JH, Peregrina JM. Synthesis of Azabicyclo[2.2.n]alkane Systems as Analogues of 3-[1-Methyl-2-(S)-pyrrolidinyl- methoxy]pyridine (A-84543). J Org Chem 2007; 72:3112-5. [PMID: 17371077 DOI: 10.1021/jo0700732] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work is connected with the epibatidine field and describes the synthesis of several analogues of compounds that present affinity for nicotinic acetylcholine receptors, such as 3-[1-methyl-2-(S)-pyrrolidinylmethoxy]pyridine (A-84543). These analogues bear a 3-pyridyl ether substituent at the bridgehead carbon of the azabicyclo[2.2.n]alkane system. Particularly, in the case of the 1-substituted 2-azabicyclo[2.2.2]octane system, a new synthetic route has been developed, which involves the synthesis of a novel rigid sulfamidate that allows the straightforward introduction of nucleophiles.
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Affiliation(s)
- J Carreras
- Departamento de Química, Universidad de La Rioja, Grupo de Síntesis Química de La Rioja, UA-CSIC, 26006 Logroño, Spain
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Vaupel DB, Stein EA, Mukhin AG. Quantification of alpha4beta2* nicotinic receptors in the rat brain with microPET and 2-[18F]F-A-85380. Neuroimage 2007; 34:1352-62. [PMID: 17187994 PMCID: PMC2023973 DOI: 10.1016/j.neuroimage.2006.10.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 09/27/2006] [Accepted: 10/13/2006] [Indexed: 11/17/2022] Open
Abstract
The radioligand 2-[(18)F]F-A-85380 has been used for PET studies of the alpha4beta2* subtype of nicotinic acetylcholine receptors (nAChRs) in the living brain of humans and nonhuman primates. In order to extend the capacity of microPET to quantify neuroreceptors in rat brain, we carried out studies of 2-[(18)F]F-A-85380 to measure the apparent binding potential BP* in individual rats, which were studied repeatedly over several months. Using a bolus-plus-infusion paradigm, 2-[(18)F]F-A-85380 (specific activity 20-1300 GBq/micromol) was administered intravenously over 8 to 9 h with K(bol) values of 350 to 440 min and a mean infusion rate of 0.03+/-0.01 nmol/kg/h. Studies included a 2-h nicotine infusion initiated 2 h before the end of scanning to displace specifically bound radioactivity. Steady state binding in brain was obtained within 5 h as defined by the occurrence of constant radioactivity concentrations in brain regions and constant, free arterial plasma levels of nonmetabolized radioligand. BP* averages (+/-SEM) for thalamus, forebrain, and cerebellum were 5.9+/-0.7, 2.6+/-0.4, and 1.0+/-0.1, respectively, which are consistent with the alpha4beta2* nAChR distribution in rat brain measured in vitro. Studies of receptor occupancy determined the ED(50) to be 0.29 nmol/kg/h. The demonstration that alpha4beta2* nAChRs are quantifiable in the rat brain using PET measurements, coupled with the ability to conduct longitudinal studies over several months in the same rats, suggests potential applications to studies of chronic nicotine use, its treatment, and abnormal functioning of alpha4beta2* receptors in a rat model.
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Affiliation(s)
- D Bruce Vaupel
- Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA.
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Dollé F. [18F]fluoropyridines: From conventional radiotracers to the labeling of macromolecules such as proteins and oligonucleotides. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2007:113-57. [PMID: 17172154 DOI: 10.1007/978-3-540-49527-7_5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
Abstract
Molecular in vivo imaging with the high-resolution and sensitive positron emission tomography (PET) technique requires the preparation of a positron-emitting radiolabeled probe or radiotracer. For this purpose, fluorine-18 is becoming increasingly the radionuclide of choice due to its adequate physical and nuclear characteristics, and also because of the successful use in clinical oncology of 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), which is currently the most widely used PET-radiopharmaceutical and probably the driving force behind the growing availability and interest for this positron-emitter in radiopharmaceutical chemistry. With a few exceptions, radiofluorinations involving fluorine-18 of high specific radioactivity (e.g. > 185 GBq/micromole) had, until recently, been limited to nucleophilic substitutions in homoaromatic and aliphatic series with [18F]fluoride. Considering chemical structures showing a fluoropyridinyl moiety, nucleophilic heteroaromatic substitution at the ortho-position with no-carrier-added [l8F]fluoride, as its K[18F]F-K222 complex, appears today as a highly efficient method for the radiosynthesis of radiotracers and radiopharmaceuticals. This chapter summarizes the recent applications of this methodology and highlights its potential in the design and preparation of, often drug-based, fluorine-18-labeled probes of high specific radioactivity for PET imaging, including macromolecules of biological interest such as peptides, proteins and oligonucleotides.
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Affiliation(s)
- F Dollé
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale - CEA, Orsay, France.
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41
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Sorger D, Becker GA, Hauber K, Schildan A, Patt M, Birkenmeier G, Otto A, Meyer P, Kluge M, Schliebs R, Sabri O. Binding properties of the cerebral alpha4beta2 nicotinic acetylcholine receptor ligand 2-[18F]fluoro-A-85380 to plasma proteins. Nucl Med Biol 2007; 33:899-906. [PMID: 17045170 DOI: 10.1016/j.nucmedbio.2006.07.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 07/26/2006] [Accepted: 07/29/2006] [Indexed: 10/24/2022]
Abstract
INTRODUCTION To determine the availability of nicotinic acetylcholine receptors in different human brain regions using the positron emission tomography (PET) radioligand 2-[18F]fluoro-A-85380 (2-[18F]FA) and invasive approaches for quantification, it is important to correct the arterial input function as well for plasma protein binding (PPB) of the radioligand as for radiolabeled metabolites accumulating in blood. This study deals with some aspects of PPB of 2-[18F]FA. METHODS Patients with different neurological disorders (n=72), such as Parkinson's disease, Alzheimer's disease and multiple sclerosis, and a group of healthy volunteers (n=15) subjected for PET imaging were analyzed for their PPB level of 2-[18F]FA using ultrafiltration. Protein gel electrophoresis of plasma samples was performed to identify the binding protein of 2-[18F]FA. The dependency of PPB on time and on free ligand concentration was analyzed to obtain the binding parameters Bmax and Kd. RESULTS Albumin was identified to be the binding protein of 2-[18F]FA. PPB of 2-[18F]FA was low at 17+/-4% and did not show significant differences between the groups of patients. Corresponding to this, a narrow range of plasma albumin of 0.62+/-0.05 mM was observed. Bmax was determined as twice the albumin concentration, which indicates two binding sites for 2-[18F]FA on the protein. No time dependence of the PPB could be observed. By relating PPB to Bmax, an average Kd value of 6.0+/-1.5 mM was obtained. CONCLUSION This study shows the dependency of PPB of 2-[18F]FA on human albumin plasma concentration. An equation utilizing Bmax and Kd to easily estimate PPB is presented.
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Affiliation(s)
- Dietlind Sorger
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany.
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Pimlott SL, Piggott M, Patterson J, Cavanagh J, Wyper DJ. SPECT imaging of the α4β2 nicotinic receptor using [5-123I]A85380. J Labelled Comp Radiopharm 2007. [DOI: 10.1002/jlcr.1192] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Brody AL, Mandelkern MA, London ED, Olmstead RE, Farahi J, Scheibal D, Jou J, Allen V, Tiongson E, Chefer SI, Koren AO, Mukhin AG. Cigarette smoking saturates brain alpha 4 beta 2 nicotinic acetylcholine receptors. ACTA ACUST UNITED AC 2006; 63:907-15. [PMID: 16894067 PMCID: PMC2773659 DOI: 10.1001/archpsyc.63.8.907] [Citation(s) in RCA: 265] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT 2-[18F]fluoro-3-(2(S)-azetidinylmethoxy) pyridine (2-F-A-85380, abbreviated as 2-FA) is a recently developed radioligand that allows for visualization of brain alpha 4 beta 2* nicotinic acetylcholine receptors (nAChRs) with positron emission tomography (PET) scanning in humans. OBJECTIVE To determine the effect of cigarette smoking on alpha 4 beta 2* nAChR occupancy in tobacco-dependent smokers. DESIGN Fourteen 2-FA PET scanning sessions were performed. During the PET scanning sessions, subjects smoked 1 of 5 amounts (none, 1 puff, 3 puffs, 1 full cigarette, or to satiety [2(1/2) to 3 cigarettes]). SETTING Academic brain imaging center. PARTICIPANTS Eleven tobacco-dependent smokers (paid volunteers). Main Outcome Measure Dose-dependent effect of smoking on occupancy of alpha 4 beta 2* nAChRs, as measured with 2-FA and PET in nAChR-rich brain regions. RESULTS Smoking 0.13 (1 to 2 puffs) of a cigarette resulted in 50% occupancy of alpha 4 beta 2* nAChRs for 3.1 hours after smoking. Smoking a full cigarette (or more) resulted in more than 88% receptor occupancy and was accompanied by a reduction in cigarette craving. A venous plasma nicotine concentration of 0.87 ng/mL (roughly 1/25th of the level achieved in typical daily smokers) was associated with 50% occupancy of alpha 4 beta 2* nAChRs. CONCLUSIONS Cigarette smoking in amounts used by typical daily smokers leads to nearly complete occupancy of alpha 4 beta 2* nAChRs, indicating that tobacco-dependent smokers maintain alpha 4 beta 2* nAChR saturation throughout the day. Because prolonged binding of nicotine to alpha 4 beta 2* nAChRs is associated with desensitization of these receptors, the extent of receptor occupancy found herein suggests that smoking may lead to withdrawal alleviation by maintaining nAChRs in the desensitized state.
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Affiliation(s)
- Arthur L Brody
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA 90095, USA.
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Brody AL. Functional brain imaging of tobacco use and dependence. J Psychiatr Res 2006; 40:404-18. [PMID: 15979645 PMCID: PMC2876087 DOI: 10.1016/j.jpsychires.2005.04.012] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 04/22/2005] [Accepted: 04/26/2005] [Indexed: 11/25/2022]
Abstract
While most cigarette smokers endorse a desire to quit smoking, only about 14% to 49% will achieve abstinence after 6 months or more of treatment. A greater understanding of the effects of smoking on brain function may (in conjunction with other lines of research) result in improved pharmacological (and behavioral) interventions. Many research groups have examined the effects of acute and chronic nicotine/cigarette exposure on brain activity using functional imaging; the purpose of this paper is to synthesize findings from such studies and present a coherent model of brain function in smokers. Responses to acute administration of nicotine/smoking include: a reduction in global brain activity; activation of the prefrontal cortex, thalamus, and visual system; activation of the thalamus and visual cortex during visual cognitive tasks; and increased dopamine (DA) concentration in the ventral striatum/nucleus accumbens. Responses to chronic nicotine/cigarette exposure include decreased monoamine oxidase (MAO) A and B activity in the basal ganglia and a reduction in alpha4beta2 nicotinic acetylcholine receptor (nAChR) availability in the thalamus and putamen. Taken together, these findings indicate that smoking enhances neurotransmission through cortico-basal ganglia-thalamic circuits either by direct stimulation of nAChRs, indirect stimulation via DA release or MAO inhibition, or a combination of these factors. Activation of this circuitry may be responsible for the effects of smoking seen in tobacco dependent subjects, such as improvements in attentional performance, mood, anxiety, and irritability.
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Affiliation(s)
- Arthur L Brody
- Department of Psychiatry and Biobehavioral Sciences, UCLA School of Medicine, 300 UCLA Medical Plaza, Suite 2200, Los Angeles, CA 90095, United States.
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Roger G, Saba W, Valette H, Hinnen F, Coulon C, Ottaviani M, Bottlaender M, Dollé F. Synthesis and radiosynthesis of [18F]FPhEP, a novel α4β2-selective, epibatidine-based antagonist for PET imaging of nicotinic acetylcholine receptors. Bioorg Med Chem 2006; 14:3848-58. [PMID: 16455259 DOI: 10.1016/j.bmc.2006.01.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 01/12/2006] [Accepted: 01/17/2006] [Indexed: 11/22/2022]
Abstract
FPhEP (1, (+/-)-2-exo-(2'-fluoro-3'-phenyl-pyridin-5'-yl)-7-azabicyclo[2.2.1]heptane) belongs to a recently described novel series of 3'-phenyl analogues of epibatidine, which not only possess subnanomolar affinity and high selectivity for brain alpha4beta2 neuronal nicotinic acetylcholine receptors (nAChRs), but also were reported as functional antagonists of low toxicity (up to 15 mg/kg in mice). FPhEP (1, K(i) of 0.24 nM against [(3)H]epibatidine) as reference as well as the corresponding N-Boc-protected chloro- and bromo derivatives (3a,b) as precursors for labelling with fluorine-18 were synthesized in eight and nine steps, respectively, from commercially available N-Boc-pyrrole (overall yields=17% for 1, 9% for 3a and 8% for 3b). FPhEP (1) was labelled with fluorine-18 using the following two-step radiochemical process: (1) no-carrier-added nucleophilic heteroaromatic ortho-radiofluorination from the corresponding N-Boc-protected chloro- or bromo derivatives (3 a,b-1mg) and the activated K[(18)F]F-Kryptofix(222) complex in DMSO using microwave activation at 250 W for 1.5 min, followed by (2) quantitative TFA-induced removal of the N-Boc-protective group. Radiochemically pure (>99%) [(18)F]FPhEP ([(18)F]-1, 2.22-3.33 GBq, 66-137 GBq/micromol) was obtained after semi-preparative HPLC (Symmetry C18, eluent aq 0.05 M NaH(2)PO(4)/CH(3)CN, 80:20 (v:v)) in 75-80 min starting from a 18.5 GBq aliquot of a cyclotron-produced [(18)F]fluoride production batch (10-20% nondecay-corrected overall yield). In vitro binding studies on rat whole-brain membranes demonstrated a subnanomolar affinity (K(D) 660 pM) of [(18)F]FPhEP ([(18)F]-1) for nAChRs. In vitro autoradiographic studies also showed a good contrast between nAChR-rich and -poor regions with a low non-specific binding. Comparison of in vivo Positron Emission Tomography (PET) kinetics of [(18)F]FPhEP ([(18)F]-1) and [(18)F]F-A-85380 in baboons demonstrated faster brain kinetics of the former compound (with a peak uptake at 20 min post injection only). Taken together, the preliminary data obtained confirm that [(18)F]FPhEP ([(18)F]-1) has potential for in vivo imaging nAChRs in the brain with PET.
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Affiliation(s)
- Gaëlle Roger
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, CEA/DSV, 4 Place du Général Leclerc, F-91401 Orsay, France
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Zaniewska M, McCreary AC, Przegaliński E, Filip M. Evaluation of the role of nicotinic acetylcholine receptor subtypes and cannabinoid system in the discriminative stimulus effects of nicotine in rats. Eur J Pharmacol 2006; 540:96-106. [PMID: 16730696 DOI: 10.1016/j.ejphar.2006.04.034] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 04/12/2006] [Accepted: 04/18/2006] [Indexed: 10/24/2022]
Abstract
Male Wistar rats were trained to discriminate (-)-nicotine (0.4 mg/kg) from saline under a two-lever, fixed-ratio 10 schedule of water reinforcement. During test sessions the following drugs were coadministered with saline (substitution studies) or nicotine (0.025-0.4 mg/kg; combination studies): the alpha4beta2 nicotinic acetylcholine receptor subtype antagonist dihydro-beta-erythroidine (DHbetaE), the non-selective nicotinic acetylcholine receptor subtype antagonist mecamylamine, the alpha7 nicotinic acetylcholine receptor subtype antagonist methyllycaconitine (MLA), the alpha4beta2 nicotinic acetylcholine receptor subtype agonist 5-iodo-3-(2(S)-azetidinylmethoxy)pyridine (5-IA), the cannabinoid CB1 receptor antagonist/partial agonist rimonabant, the cannabinoid CB2 receptor antagonist N-[(1S)-endo-1,3,3-trimethylbicyclo-[2.2.1]heptan-2-yl]5-(4-chloro-3-methyl-phenyl)-1-(4-methybenzyl)pyrazole-3-carboxamide (SR 144528), the cannabinoid CB1/2 receptor agonists (-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)-phenyl]-trans-4-(3-hydroxy-propyl)cyclohexanol (CP 55,940) or R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]-pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-(1-naphthalenyl)-methanone mesylate (WIN 55,212-2), the endogenous cannabinoid agonist and non-competitive alpha7 nicotinic acetylcholine receptor subtype antagonist anandamide, the anandamide uptake and fatty acid amide hydrolase inhibitor N-(4-hydroxyphenyl)-5Z,8Z,11Z,14Z-eicosatetraenamide (AM-404), the fatty acid amide hydrolase inhibitor cyclohexylcarbamic acid 3'-carbamoyl-biphenyl-3-yl ester (URB 597), AM-404+anandamide or URB 597+anandamide. 5-IA (0.01 mg/kg) fully substituted for nicotine, while other drugs were inactive. In combination studies, DHbetaE and mecamylamine dose-dependently attenuated the discriminative stimulus effects of nicotine and the full substitution of 5-IA, while MLA, rimonabant, SR 144528, CP 55,940, WIN 55,212-2, and URB 597 did not alter the nicotine cue. Pretreatment with AM-404+anandamide or URB 597+anandamide weakly enhanced nicotine-lever responding. Our pharmacological analyses demonstrates that the expression of nicotine discrimination is under the control of nicotinic acetylcholine receptor subtypes composed of alpha4beta2 (but not of alpha7) subunits. Furthermore, we excluded the involvement of either cannabinoid CB1 and CB2 receptors or increases in the endocannabinoid tone in the nicotine discrimination.
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MESH Headings
- Aconitine/analogs & derivatives
- Aconitine/pharmacology
- Animals
- Arachidonic Acids/pharmacology
- Azetidines/pharmacology
- Benzamides/pharmacology
- Benzoxazines
- Camphanes/pharmacology
- Cannabinoid Receptor Antagonists
- Carbamates/pharmacology
- Cyclohexanols/pharmacology
- Dihydro-beta-Erythroidine/pharmacology
- Discrimination Learning/drug effects
- Discrimination Learning/physiology
- Dose-Response Relationship, Drug
- Drug Synergism
- Endocannabinoids
- Male
- Mecamylamine/pharmacology
- Morpholines/pharmacology
- Naphthalenes/pharmacology
- Nicotine/pharmacology
- Nicotinic Agonists/pharmacology
- Nicotinic Antagonists/pharmacology
- Polyunsaturated Alkamides/pharmacology
- Pyrazoles/pharmacology
- Pyridines/pharmacology
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/physiology
- Receptors, Cannabinoid/physiology
- Receptors, Nicotinic/physiology
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Affiliation(s)
- Magdalena Zaniewska
- Institute of Pharmacology, Polish Academy of Sciences, 31-343, Kraków, 12 Smetna, Poland
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Baldwin RM, Zoghbi SS, Staley JK, Brenner E, Al-Tikriti MS, Amici L, Fujita M, Innis RB, Tamagnan G. Chemical fate of the nicotinic acetylcholinergic radiotracer [123I]5-IA-85380 in baboon brain and plasma. Nucl Med Biol 2006; 33:549-54. [PMID: 16720248 DOI: 10.1016/j.nucmedbio.2006.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Revised: 02/21/2006] [Accepted: 03/06/2006] [Indexed: 11/26/2022]
Abstract
The fate of the nicotinic acetylcholinergic receptor radiotracer [123I]5-IA-85380 ([123I]5-IA) was studied in baboon by analyzing the chemical composition of brain tissue and plasma after intravenous administration of the tracer. Acetonitrile denaturation and high-performance liquid chromatography (HPLC) analysis showed predominantly unchanged (91-98%) parent tracer in all brain tissues examined, compared to significant metabolism (23% parent) in the plasma at 90 min postinjection, and control tissue recovery of 95-98%. [123I]5-IA was distributed to the thalamus with a standardized uptake value of 9.2 (0.04% dose/g) or a concentration 5.8 times higher than that of the cerebellum. The HPLC behavior of a synthesized sample of one hypothesized metabolite, 5-iodo-3-pyridinol (5-IP), was consistent with plasma radiometabolite fraction. Since only parent radiotracer compound was found in brain tissue, these results add confidence that information derived from single photon emission computed tomography images of 123I activity in the brain after [123I]5-IA administration can be interpreted as distribution of an intact radiotracer.
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Affiliation(s)
- Ronald M Baldwin
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA.
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Schmaljohann J, Gündisch D, Minnerop M, Bucerius J, Joe A, Reinhardt M, Guhlke S, Biersack HJ, Wüllner U. In vitro evaluation of nicotinic acetylcholine receptors with 2-[18F]F-A85380 in Parkinson's disease. Nucl Med Biol 2006; 33:305-9. [PMID: 16631078 DOI: 10.1016/j.nucmedbio.2005.12.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 12/05/2005] [Accepted: 12/06/2005] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine receptors (nAChR) are involved in many physiological functions and appear to be affected in neurodegenerative diseases like Alzheimer's disease and Parkinson's disease (PD). Here, we describe the in vitro evaluation of nAChRs in PD with 2-[18F]F-A85380, a ligand with high affinity to the beta2 nAChR subunit. Autoradiography with 2-[18F]F-A85380 in untreated rat brain corresponded to the known distribution of alpha4beta2 nAChRs with high uptake in the thalamus, moderate uptake in the striatum and cortex and low uptake in the cerebellum (47%, 43% and 19% of the thalamus, respectively). The localization of alpha4beta2 nAChRs in the striatum was investigated in rodents with unilateral lesion of the substantia nigra. 2-[18F]F-A85380 binding was significantly reduced in the striatum ipsilateral to the lesion side (to 64% of the contralateral side), indicating that a fraction of alpha4beta2 nAChRs is located on dopaminergic terminals, whereas another fraction resides on striatal interneurons or cortical afferents. Similarly, in human brain sections of PD patients, 2-[18F]F-A85380 uptake was significantly reduced not only in the caudate and putamen but also in the thalamus (approximately 30% of the binding of control brain in all three regions); within the striatum, nAChRs in the putamen were significantly more severely affected as in the caudate. The observed pattern of alpha4beta2* nAChR loss demonstrates the potential of 2-[18F]F-A85380 for further investigations of this positron emission tomography ligand for in vivo studies of alpha4beta2* nAChRs in PD.
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Zhang CX, Ge ZM, Cheng TM, Li RT. Synthesis and analgesic activity of secondary amine analogues of pyridylmethylamine and positional isomeric analogues of ABT-594. Bioorg Med Chem Lett 2006; 16:2013-6. [PMID: 16412637 DOI: 10.1016/j.bmcl.2005.12.073] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 11/30/2005] [Accepted: 12/19/2005] [Indexed: 11/20/2022]
Abstract
A series of highly sterically hindered secondary amine analogues of pyridylmethylamine (7a-f, 8a-c) and positional isomeric analogues of ABT-594 (9a-c) were synthesized and evaluated for their in vivo analgesic activity. The compounds 7a and 7d show potent analgesic activity and lower toxicity. Some interesting structure-activity relationships have been revealed.
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Affiliation(s)
- Chuan-Xin Zhang
- School of Pharmaceutical Sciences, Peking University, Beijing 100083, PR China
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50
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Roger G, Hinnen F, Valette H, Saba W, Bottlaender M, Dollé F. Radiosynthesis of 2-exo-(2′-[18F]Fluoro-3′-(4-fluorophenyl)-pyridin-5′-yl)-7-azabicyclo[2.2.1]heptane ([18F]F2PhEP), a potent epibatidine-based radioligand for nicotinic acetylcholine receptor PET imaging. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.1063] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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