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Nagori K, Pradhan M, Sharma M, Ajazuddin, Badwaik HR, Nakhate KT. Current Progress on Central Cholinergic Receptors as Therapeutic Targets for Alzheimer's Disease. Curr Alzheimer Res 2024; 21:50-68. [PMID: 38529600 DOI: 10.2174/0115672050306008240321034006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/22/2024] [Accepted: 02/26/2024] [Indexed: 03/27/2024]
Abstract
Acetylcholine (ACh) is ubiquitously present in the nervous system and has been involved in the regulation of various brain functions. By modulating synaptic transmission and promoting synaptic plasticity, particularly in the hippocampus and cortex, ACh plays a pivotal role in the regulation of learning and memory. These procognitive actions of ACh are mediated by the neuronal muscarinic and nicotinic cholinergic receptors. The impairment of cholinergic transmission leads to cognitive decline associated with aging and dementia. Therefore, the cholinergic system has been of prime focus when concerned with Alzheimer's disease (AD), the most common cause of dementia. In AD, the extensive destruction of cholinergic neurons occurs by amyloid-β plaques and tau protein-rich neurofibrillary tangles. Amyloid-β also blocks cholinergic receptors and obstructs neuronal signaling. This makes the central cholinergic system an important target for the development of drugs for AD. In fact, centrally acting cholinesterase inhibitors like donepezil and rivastigmine are approved for the treatment of AD, although the outcome is not satisfactory. Therefore, identification of specific subtypes of cholinergic receptors involved in the pathogenesis of AD is essential to develop future drugs. Also, the identification of endogenous rescue mechanisms to the cholinergic system can pave the way for new drug development. In this article, we discussed the neuroanatomy of the central cholinergic system. Further, various subtypes of muscarinic and nicotinic receptors involved in the cognition and pathophysiology of AD are described in detail. The article also reviewed primary neurotransmitters that regulate cognitive processes by modulating basal forebrain cholinergic projection neurons.
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Affiliation(s)
- Kushagra Nagori
- Department of Pharmaceutical Chemistry, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Madhulika Pradhan
- Department of Pharmaceutical Technology, Gracious College of Pharmacy, Abhanpur 493661, Chhattisgarh, India
| | - Mukesh Sharma
- Department of Pharmacognosy, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Ajazuddin
- Department of Pharmaceutics, Rungta College of Pharmaceutical Sciences and Research, Kurud Road, Kohka, Bhilai 490024, Chhattisgarh, India
| | - Hemant R Badwaik
- Department of Pharmaceutical Chemistry, Shri Shankaracharya Institute of Pharmaceutical Sciences and Research, Junwani, Bhilai 490020, Chhattisgarh, India
| | - Kartik T Nakhate
- Department of Pharmacology, Shri Vile Parle Kelavani Mandal's Institute of Pharmacy, Dhule 424001, Maharashtra, India
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Zhang JJ, Fu H, Lin R, Zhou J, Haider A, Fang W, Elghazawy NH, Rong J, Chen J, Li Y, Ran C, Collier TL, Chen Z, Liang SH. Imaging Cholinergic Receptors in the Brain by Positron Emission Tomography. J Med Chem 2023; 66:10889-10916. [PMID: 37583063 PMCID: PMC10461233 DOI: 10.1021/acs.jmedchem.3c00573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Indexed: 08/17/2023]
Abstract
Cholinergic receptors represent a promising class of diagnostic and therapeutic targets due to their significant involvement in cognitive decline associated with neurological disorders and neurodegenerative diseases as well as cardiovascular impairment. Positron emission tomography (PET) is a noninvasive molecular imaging tool that has helped to shed light on the roles these receptors play in disease development and their diverse functions throughout the central nervous system (CNS). In recent years, there has been a notable advancement in the development of PET probes targeting cholinergic receptors. The purpose of this review is to provide a comprehensive overview of the recent progress in the development of these PET probes for cholinergic receptors with a specific focus on ligand structure, radiochemistry, and pharmacology as well as in vivo performance and applications in neuroimaging. The review covers the structural design, pharmacological properties, radiosynthesis approaches, and preclinical and clinical evaluations of current state-of-the-art PET probes for cholinergic receptors.
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Affiliation(s)
- Jing-Jing Zhang
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization of Forest
Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization
of Agro-Forest Biomass, Jiangsu Key Lab of Biomass-Based Green Fuels
and Chemicals, International Innovation Center for Forest Chemicals
and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Hualong Fu
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ruofan Lin
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization of Forest
Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization
of Agro-Forest Biomass, Jiangsu Key Lab of Biomass-Based Green Fuels
and Chemicals, International Innovation Center for Forest Chemicals
and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ahmed Haider
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Weiwei Fang
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization of Forest
Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization
of Agro-Forest Biomass, Jiangsu Key Lab of Biomass-Based Green Fuels
and Chemicals, International Innovation Center for Forest Chemicals
and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Nehal H. Elghazawy
- Department
of Pharmaceutical, Chemistry, Faculty of Pharmacy & Biotechnology, German University in Cairo, 11835 Cairo, Egypt
| | - Jian Rong
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Jiahui Chen
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Yinlong Li
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Chongzhao Ran
- Athinoula
A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02114, United States
| | - Thomas L. Collier
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Zhen Chen
- Jiangsu
Co-Innovation Center of Efficient Processing and Utilization of Forest
Resources, Jiangsu Provincial Key Lab for the Chemistry and Utilization
of Agro-Forest Biomass, Jiangsu Key Lab of Biomass-Based Green Fuels
and Chemicals, International Innovation Center for Forest Chemicals
and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
| | - Steven H. Liang
- Division
of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital
& Department of Radiology, Harvard Medical
School, Boston, Massachusetts 02114, United States
- Department
of Radiology and Imaging Sciences, Emory
University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
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3
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Zhang HJ, Zammit M, Kao CM, Govind AP, Mitchell S, Holderman N, Bhuiyan M, Freifelder R, Kucharski A, Zhuang X, Mukherjee J, Chen CT, Green WN. Trapping of Nicotinic Acetylcholine Receptor Ligands Assayed by In Vitro Cellular Studies and In Vivo PET Imaging. J Neurosci 2023; 43:2-13. [PMID: 36028313 PMCID: PMC9838697 DOI: 10.1523/jneurosci.2484-21.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 08/07/2022] [Accepted: 08/13/2022] [Indexed: 01/19/2023] Open
Abstract
A question relevant to nicotine addiction is how nicotine and other nicotinic receptor membrane-permeant ligands, such as the anti-smoking drug varenicline (Chantix), distribute in brain. Ligands, like varenicline, with high pKa and high affinity for α4β2-type nicotinic receptors (α4β2Rs) are trapped in intracellular acidic vesicles containing α4β2Rs in vitro Nicotine, with lower pKa and α4β2R affinity, is not trapped. Here, we extend our results by imaging nicotinic PET ligands in vivo in male and female mouse brain and identifying the trapping brain organelle in vitro as Golgi satellites (GSats). Two PET 18F-labeled imaging ligands were chosen: [18F]2-FA85380 (2-FA) with varenicline-like pKa and affinity and [18F]Nifene with nicotine-like pKa and affinity. [18F]2-FA PET-imaging kinetics were very slow consistent with 2-FA trapping in α4β2R-containing GSats. In contrast, [18F]Nifene kinetics were rapid, consistent with its binding to α4β2Rs but no trapping. Specific [18F]2-FA and [18F]Nifene signals were eliminated in β2 subunit knock-out (KO) mice or by acute nicotine (AN) injections demonstrating binding to sites on β2-containing receptors. Chloroquine (CQ), which dissipates GSat pH gradients, reduced [18F]2-FA distributions while having little effect on [18F]Nifene distributions in vivo consistent with only [18F]2-FA trapping in GSats. These results are further supported by in vitro findings where dissipation of GSat pH gradients blocks 2-FA trapping in GSats without affecting Nifene. By combining in vitro and in vivo imaging, we mapped both the brain-wide and subcellular distributions of weak-base nicotinic receptor ligands. We conclude that ligands, such as varenicline, are trapped in neurons in α4β2R-containing GSats, which results in very slow release long after nicotine is gone after smoking.SIGNIFICANCE STATEMENT Mechanisms of nicotine addiction remain poorly understood. An earlier study using in vitro methods found that the anti-smoking nicotinic ligand, varenicline (Chantix) was trapped in α4β2R-containing acidic vesicles. Using a fluorescent-labeled high-affinity nicotinic ligand, this study provided evidence that these intracellular acidic vesicles were α4β2R-containing Golgi satellites (GSats). In vivo PET imaging with F-18-labeled nicotinic ligands provided additional evidence that differences in PET ligand trapping in acidic vesicles were the cause of differences in PET ligand kinetics and subcellular distributions. These findings combining in vitro and in vivo imaging revealed new mechanistic insights into the kinetics of weak base PET imaging ligands and the subcellular mechanisms underlying nicotine addiction.
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Affiliation(s)
- Hannah J Zhang
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Matthew Zammit
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Chien-Min Kao
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Anitha P Govind
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - Samuel Mitchell
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | | | - Mohammed Bhuiyan
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | | | - Anna Kucharski
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - Xiaoxi Zhuang
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
| | - Jogeshwar Mukherjee
- Departments of Preclinical Imaging and Radiological Sciences, University of California, Irvine, California 92697
| | - Chin-Tu Chen
- Department of Radiology, University of Chicago, Chicago, Illinois 60637
| | - William N Green
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543
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5
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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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6
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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7
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Garibotto V, Corpataux T, Dupuis-Lozeron E, Haller S, Fontolliet T, Picard F. Higher nicotinic receptor availability in the cingulo-insular network is associated with lower cardiac parasympathetic tone. J Comp Neurol 2019; 527:3014-3022. [PMID: 31168797 DOI: 10.1002/cne.24726] [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: 12/23/2018] [Revised: 05/07/2019] [Accepted: 05/23/2019] [Indexed: 12/18/2022]
Abstract
The dorsal anterior cingulate cortex (dACC) and the anterior insula (AI) constitute the salience network and form as well the major cortical components of the central autonomic nervous system. These two cortical regions have the highest density in α4β2 nicotinic acetylcholine receptors (nAChRs) within the whole cortex.The aim of the study was to test the association between nAChRs density/availability in the salience network and the heart rate variability in humans. We selected subjects from a previous positron emission tomography (PET) imaging study in epilepsy with 18F-FA-85380, a specific marker for α4β2 nAChRs, including 10 healthy controls, 10 patients with nonlesional focal epilepsy and 8 patients with idiopathic generalized epilepsy. Participants underwent a 10 min-resting electrocardiogram as they were lying still in a semi-supine position while watching an emotionally neutral video. We tested the association between parasympathetic tone and the regional brain nAChR availability, as measured by 18F-F-A-85380 binding potential (BP), using linear regression. We observed an association between higher nAChRs availability in the bilateral dACC and the right dorsal AI/frontal operculum and a lower parasympathetic tone, without significant effect of the clinical group on this relation. Our study is the first one to show a neurochemical correlate to the parasympathetic role of the anterior cingulate cortex and the AI. The nicotinic system, which plays a major role in the peripheral autonomic nervous system intervening both in the parasympathetic and sympathetic chains, seems also to play a role in the central autonomic nervous system.
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Affiliation(s)
- Valentina Garibotto
- Faculty of Medicine, Geneva University, Geneva, Switzerland.,Nuclear Medicine and Molecular Imaging Division, Department of Medical Imaging, University Hospitals of Geneva, Geneva, Switzerland
| | | | - Elise Dupuis-Lozeron
- Division of Clinical Epidemiology, Geneva University Hospitals, Geneva, Switzerland
| | - Sven Haller
- Faculty of Medicine, Geneva University, Geneva, Switzerland.,Centre d'Imagerie Rive Droite, Geneva, Switzerland.,Department of Surgical Sciences, Radiology, Uppsala University, Uppsala, Sweden
| | - Timothée Fontolliet
- Departement of Anesthesiology, Pharmacology and Intensive Care, Department of Basic Neurosciences, Geneva University, Geneva, Switzerland
| | - Fabienne Picard
- Faculty of Medicine, Geneva University, Geneva, Switzerland.,EEG and Epilepsy Unit, Department of Neurology, University Hospitals of Geneva, Geneva, Switzerland
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Coughlin JM, Slania S, Du Y, Rosenthal HB, Lesniak WG, Minn I, Smith GS, Dannals RF, Kuwabara H, Wong DF, Wang Y, Horti AG, Pomper MG. 18F-XTRA PET for Enhanced Imaging of the Extrathalamic α4β2 Nicotinic Acetylcholine Receptor. J Nucl Med 2018; 59:1603-1608. [PMID: 29496987 DOI: 10.2967/jnumed.117.205492] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 02/03/2018] [Indexed: 11/16/2022] Open
Abstract
Reduced density of the α4β2 nicotinic acetylcholine receptor (α4β2-nAChR) in the cortex and hippocampus of the human brain has been reported in aging and patients with neurodegenerative disease. This study assessed the pharmacokinetic behavior of 18F-(-)-JHU86428 (18F-XTRA), a new radiotracer for in vivo PET imaging of the α4β2-nAChR, particularly in extrathalamic regions of interest in which the α4β2-nAChR is less densely expressed than in thalamus. 18F-XTRA was also used to evaluate the α4β2-nAChR in the hippocampus in human aging. Methods: Seventeen healthy nonsmoker adults (11 men, 6 women; age, 30-82 y) underwent PET neuroimaging over 90 or 180 min in a high-resolution research tomograph after bolus injection of 18F-XTRA. Methods to quantify binding of 18F-XTRA to the α4β2-nAChR in the human brain were compared, and the relationship between age and binding in the hippocampus was tested. Results: 18F-XTRA rapidly entered the brain, and time-activity curves peaked within 10 min after injection for extrathalamic regions and at approximately 70 min in the thalamus. The 2-tissue-compartment model (2TCM) predicted the regional time-activity curves better than the 1-tissue-compartment model, and total distribution volume (VT) was well identified by the 2TCM in all ROIs. VT values estimated using Logan analysis with metabolite-corrected arterial input were highly correlated with those from the 2TCM in all regions, and values from 90-min scan duration were on average within 5% of those values from 180 min of data. Parametric images of VT were consistent with the known distribution of the α4β2-nAChR across the brain. Finally, an inverse correlation between VT in the hippocampus and age was observed. Conclusion: Our results extend support for use of 18F-XTRA with 90 min of emission scanning in quantitative human neuroimaging of the extrathalamic α4β2-nAChR, including in studies of aging.
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Affiliation(s)
- Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Stephanie Slania
- Department of Biomedical Engineering, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Hailey B Rosenthal
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Wojciech G Lesniak
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Il Minn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Gwenn S Smith
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Hiroto Kuwabara
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Dean F Wong
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Department of Neuroscience, Johns Hopkins Medical Institutions, Baltimore, Maryland; and.,Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Andrew G Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland .,Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland.,Department of Biomedical Engineering, Johns Hopkins Medical Institutions, Baltimore, Maryland
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9
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Kassenbrock A, Vasdev N, Liang SH. Selected PET Radioligands for Ion Channel Linked Neuroreceptor Imaging: Focus on GABA, NMDA and nACh Receptors. Curr Top Med Chem 2017; 16:1830-42. [PMID: 26975506 DOI: 10.2174/1568026616666160315142457] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 08/01/2015] [Accepted: 08/03/2015] [Indexed: 12/11/2022]
Abstract
Positron emission tomography (PET) neuroimaging of ion channel linked receptors is a developing area of preclinical and clinical research. The present review focuses on recent advances with radiochemistry, preclinical and clinical PET imaging studies of three receptors that are actively pursued in neuropsychiatric drug discovery: namely the γ-aminobutyric acid-benzodiazapine (GABA) receptor, nicotinic acetylcholine receptor (nAChR), and N-methyl-D-aspartate (NMDA) receptor. Recent efforts to develop new PET radioligands for these targets with improved brain uptake, selectivity, stability and pharmacokinetics are highlighted.
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Affiliation(s)
| | | | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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10
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Imaging α4β2 Nicotinic Acetylcholine Receptors (nAChRs) in Baboons with [18F]XTRA, a Radioligand with Improved Specific Binding in Extra-Thalamic Regions. Mol Imaging Biol 2016; 19:280-288. [DOI: 10.1007/s11307-016-0999-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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11
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Horti AG, Wang Y, Minn I, Lan X, Wang J, Koehler RC, Alkayed NJ, Dannals RF, Pomper MG. 18F-FNDP for PET Imaging of Soluble Epoxide Hydrolase. J Nucl Med 2016; 57:1817-1822. [PMID: 27417650 DOI: 10.2967/jnumed.116.173245] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/16/2016] [Indexed: 12/29/2022] Open
Abstract
Soluble epoxide hydrolase (sEH) is a bifunctional enzyme located within cytosol and peroxisomes that converts epoxides to the corresponding diols and hydrolyzes phosphate monoesters. It serves to inactivate epoxyeicosatrienoic acids (EETs), which are generated in the brain to couple neuronal activity and cerebral blood flow in normal and pathologic states. Altered regulation of sEH was observed previously in various neuropathologic disorders including vascular dementia and stroke. Inhibitors of sEH are pursued as agents to mitigate neuronal damage after stroke. We developed N-(3,3-diphenylpropyl)-6-18F-fluoronicotinamide (18F-FNDP), which proved highly specific for imaging of sEH in the mouse and nonhuman primate brain with PET. METHODS 18F-FNDP was synthesized from the corresponding bromo precursor. sEH inhibitory activity of 18F-FNDP was measured using an sEH inhibitor screening assay kit. Biodistribution was undertaken in CD-1 mice. Binding specificity was assayed in CD-1 and sEH knock-out mice and Papio anubis (baboon) through pretreatment with an sEH inhibitor to block sEH binding. Dynamic PET imaging with arterial blood sampling was performed in 3 baboons, with regional tracer binding quantified using distribution volume. The metabolism of 18F-FNDP in baboons was assessed using high-performance liquid chromatography. RESULTS 18F-FNDP (inhibition binding affinity constant, 1.73 nM) was prepared in 1 step in a radiochemical yield of 14% ± 7%, specific radioactivity in the range of 888-3,774 GBq/μmol, and a radiochemical purity greater than 99% using an automatic radiosynthesis module. The time of preparation was about 75 min. In CD-1 mice, regional uptake followed the pattern of striatum > cortex > hippocampus > cerebellum, consistent with the known brain distribution of sEH, with 5.2% injected dose per gram of tissue at peak uptake. Blockade of 80%-90% was demonstrated in all brain regions. Minimal radiotracer uptake was present in sEH knock-out mice. PET baboon brain distribution paralleled that seen in mouse, with a marked blockade (95%) noted in all regions indicating sEH-mediated uptake of 18F-FNDP. Two hydrophilic metabolites were identified, with 20% parent compound present at 90 min after injection in baboon plasma. CONCLUSION 18F-FNDP can be synthesized in suitable radiochemical yield and high specific radioactivity and purity. In vivo imaging experiments demonstrated that 18F-FNDP targeted sEH in murine and nonhuman primate brain specifically. 18F-FNDP is a promising PET radiotracer likely to be useful for understanding the role of sEH in a variety of conditions affecting the central nervous system.
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Affiliation(s)
- Andrew G Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Il Minn
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Xi Lan
- Department of Neurology, Anesthesiology & Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland; and
| | - Jian Wang
- Department of Neurology, Anesthesiology & Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland; and
| | - Raymond C Koehler
- Department of Neurology, Anesthesiology & Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland; and
| | - Nabil J Alkayed
- Department of Anesthesiology & Perioperative Medicine, Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon
| | - Robert F Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Martin G Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
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12
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Abstract
During the past years, non-neuronal vascular nicotinic acetylcholine receptors (nAChRs) increasingly have gained interest in cardiovascular research, as they are known to mediate the deleterious effects of nicotine and nitrosamines, components of tobacco smoke, on the vasculature. Because smoking is a major risk factor for the development of atherosclerosis, it is obvious that understanding the pathophysiologic role of nAChRs in the atherosclerotic disease process, as well as in the development of new diagnostic and therapeutic nAChR-related options, has become more important. Accordingly, we briefly summarize the pathophysiologic role of vascular nAChRs in the atherosclerotic disease process. We also provide an overview of currently available nAChR positron emission tomography (PET) tracers and their performance in the noninvasive imaging of vascular nAChRs, as well as potential nAChR PET tracers that might be an option for vascular nAChR PET imaging in the future.
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Affiliation(s)
- Matthias Bauwens
- Department of Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
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13
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Horti AG, Wong DF. Clinical Perspective and Recent Development of PET Radioligands for Imaging Cerebral Nicotinic Acetylcholine Receptors. PET Clin 2016; 4:89-100. [PMID: 20046884 DOI: 10.1016/j.cpet.2009.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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14
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Preshlock S, Tredwell M, Gouverneur V. (18)F-Labeling of Arenes and Heteroarenes for Applications in Positron Emission Tomography. Chem Rev 2016; 116:719-66. [PMID: 26751274 DOI: 10.1021/acs.chemrev.5b00493] [Citation(s) in RCA: 477] [Impact Index Per Article: 59.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Diverse radiochemistry is an essential component of nuclear medicine; this includes imaging techniques such as positron emission tomography (PET). As such, PET can track diseases at an early stage of development, help patient care planning through personalized medicine and support drug discovery programs. Fluorine-18 is the most frequently used radioisotope in PET radiopharmaceuticals for both clinical and preclinical research. Its physical and nuclear characteristics (97% β(+) decay, 109.8 min half-life, 635 keV positron energy) and high specific activity make it an attractive nuclide for labeling and molecular imaging. Arenes and heteroarenes are privileged candidates for (18)F-incorporation as they are metabolically robust and therefore widely used by medicinal chemists and radiochemists alike. For many years, the range of (hetero)arenes amenable to (18)F-fluorination was limited by the lack of chemically diverse precursors, and of radiochemical methods allowing (18)F-incorporation in high selectivity and efficiency (radiochemical yield and purity, specific activity, and radio-scalability). The appearance of late-stage fluorination reactions catalyzed by transition metal or small organic molecules (organocatalysis) has encouraged much research on the use of these activation manifolds for (18)F-fluorination. In this piece, we review all of the reactions known to date to install the (18)F substituent and other key (18)F-motifs (e.g., CF3, CHF2, OCF3, SCF3, OCHF2) of medicinal relevance onto (hetero)arenes. The field has changed significantly in the past five years, and the current trend suggests that the radiochemical space available for PET applications will expand rapidly in the near future.
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Affiliation(s)
- Sean Preshlock
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Matthew Tredwell
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
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15
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[(125)I]Iodo-ASEM, a specific in vivo radioligand for α7-nAChR. Nucl Med Biol 2015; 42:488-493. [PMID: 25687449 DOI: 10.1016/j.nucmedbio.2014.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/25/2014] [Accepted: 12/10/2014] [Indexed: 11/22/2022]
Abstract
[(125)I]Iodo-ASEM, a new radioligand with high affinity and selectivity for α7-nAChRs (K(i) = 0.5 nM; α7/α4β2 = 3414), has been synthesized in radiochemical yield of 33 ± 6% from the corresponding di-butyltriazene derivative and at high specific radioactivity (1600Ci/mmol; 59.2 MBq/μmol). [(125)I]Iodo-ASEM readily entered the brains of normal CD-1 mice and specifically and selectively labeled cerebral α7-nAChRs. [(125)I]iodo-ASEM is a new useful tool for studying α7-nAChR.
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16
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Wong DF, Kuwabara H, Kim J, Brasic JR, Chamroonrat W, Gao Y, Valentine H, Willis W, Mathur A, McCaul ME, Wand G, Gean EG, Dannals RF, Horti AG. PET imaging of high-affinity α4β2 nicotinic acetylcholine receptors in humans with 18F-AZAN, a radioligand with optimal brain kinetics. J Nucl Med 2013; 54:1308-14. [PMID: 23801676 DOI: 10.2967/jnumed.112.108001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED We evaluated (-)-2-(6-[(18)F]fluoro-2,3'-bipyridin-5'-yl)-7-methyl-7-aza-bicyclo[2.2.1]heptane ((18)F-AZAN), a novel radiotracer that binds to α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) and shows high specific binding and rapid and reversible kinetics in the baboon and human brain. METHODS We tested safety tolerability and test-retest reliability (n = 5) and proposed initial quantification of (18)F-AZAN receptors in 3 healthy human subjects who had nicotine exposure and 9 who did not. We also present a receptor blocking study in a nicotine subject dosed with the α4β2-nAChR-selective partial agonist varenicline. RESULTS Radiation dosimetry PET/CT experiments indicated that most human organs received doses between 0.008 and 0.015 mSv/MBq, with an effective dose of approximately 0.014 mSv/MBq. The tracer rapidly entered the brain, and the peak was reached before 20 min, even for thalamus. Ninety-minute scans were sufficient for (18)F-AZAN to obtain the ratio at equilibrium of specifically bound radioligand to nondisplaceable radioligand in tissue (BPND) using plasma reference graphical analysis, which showed excellent reproducibility of BPND (test-retest variability < 10%) in the nAChR-rich brain regions. Regional plasma reference graphical analysis BP(ND) values exceeded 2 in the midbrain tegmental nuclei, lateral geniculate body, and thalamus for nonsmokers (n = 9) but were less than 1 in the nAChR-poor brain regions. There was a dramatic reduction of (18)F-AZAN brain uptake in smokers and varenicline-treated subjects. CONCLUSION (18)F-AZAN is a highly specific, safe, and effective PET radioligand for human subjects that requires only 90 min of PET scanning to estimate high-affinity α4β2-nAChR in the living human brain.
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Affiliation(s)
- Dean F Wong
- Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
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17
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Picard F, Sadaghiani S, Leroy C, Courvoisier DS, Maroy R, Bottlaender M. High density of nicotinic receptors in the cingulo-insular network. Neuroimage 2013; 79:42-51. [PMID: 23631995 DOI: 10.1016/j.neuroimage.2013.04.074] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/04/2013] [Accepted: 04/18/2013] [Indexed: 01/10/2023] Open
Abstract
The nicotinic system plays an important role in ordinary cognition, particularly in attention. The main nicotinic receptor in the human brain is the heteromeric α4β2 neuronal nicotinic acetylcholine receptor (nAChR), which is distributed throughout the brain, with an especially high density in the thalamus and brainstem. Despite the important role of α4β2 nAChRs in various physiological functions and pathological conditions, their distribution in the human cortex remains poorly characterized. We assessed the in vivo distribution of α4β2 nAChRs in the human cortex in a group of seven non-smoking healthy subjects, using 2-[(18)F]F-A-85380 PET and a volume-of-interest-based analysis. We showed that cortical nAChR density was highest in the insular and anterior cingulate cortices. In functional magnetic resonance imaging studies, these two cortical regions and the thalamus have been shown to be highly correlated during the resting state and various tasks. Here, we also directly assessed nAChR density in this cingulo-insular network as defined in an independent dataset using resting-state functional connectivity, and compared it to other control-related networks, to the default mode network as well as to sensory and motor networks. Receptor density was significantly higher in the cingulo-insular network. This network has been suggested to maintain a variety of foundational capacities fundamental to cognitive function. The demonstration of a high nAChR density in the insular and anterior cingulate cortices reflects a particular neurochemical organization of the cingulo-insular network, and suggests an important role of the nicotinic receptors in its functions.
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Affiliation(s)
- Fabienne Picard
- Department of Neurology, University Hospital and Medical School of Geneva, Switzerland.
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18
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Horti AG, Kuwabara H, Holt DP, Dannals RF, Wong DF. Recent PET radioligands with optimal brain kinetics for imaging nicotinic acetylcholine receptors. J Labelled Comp Radiopharm 2013; 56:159-66. [DOI: 10.1002/jlcr.3020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 11/27/2012] [Accepted: 12/07/2012] [Indexed: 01/28/2023]
Affiliation(s)
- Andrew G. Horti
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Hiroto Kuwabara
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Daniel P. Holt
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Robert F. Dannals
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
| | - Dean F. Wong
- Division of Nuclear Medicine, Department of Radiology; Johns Hopkins University; Baltimore; MD; USA
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19
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Fischer S, Hiller A, Smits R, Hoepping A, Funke U, Wenzel B, Cumming P, Sabri O, Steinbach J, Brust P. Radiosynthesis of racemic and enantiomerically pure (-)-[18F]flubatine--a promising PET radiotracer for neuroimaging of α4β2 nicotinic acetylcholine receptors. Appl Radiat Isot 2013; 74:128-36. [PMID: 23416407 DOI: 10.1016/j.apradiso.2013.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 12/07/2012] [Accepted: 01/01/2013] [Indexed: 10/27/2022]
Abstract
(-)-[(18)F]flubatine is a promising agent for visualization by PET of cerebral α4β2 nicotinic acetylcholine receptors (nAChRs), which are implicated in psychiatric and neurodegenerative disorders. Here, we describe a substantially improved two-step radiosynthesis strategy for (-)-[(18)F]flubatine, based on the nucleophilic radiofluorination of an enantiomerically pure precursor followed by deprotection of the intermediate. An extensive leaving group/protecting group library of precursors was tested. Application of a trimethylammonium-iodide precursor with a Boc-protecting group provided the best results: labeling efficiencies of 80-95%, RCY of 60±5%, radiochemical purity of >98%, and a specific activity of >350GBq/μmol. The radiosynthesis is easily transferable to an automated synthesis module.
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Affiliation(s)
- Steffen Fischer
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmacy, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstrasse 15, Leipzig, Germany
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20
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Kuwabara H, Wong DF, Gao Y, Valentine H, Holt DP, Ravert HT, Dannals RF, Horti AG. PET Imaging of Nicotinic Acetylcholine Receptors in Baboons with 18F-AZAN, a Radioligand with Improved Brain Kinetics. J Nucl Med 2011; 53:121-9. [DOI: 10.2967/jnumed.111.092338] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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21
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Gao Y, Wang H, Mease RC, Pomper MG, Horti AG. Improved Syntheses of Precursors for PET Radioligands [F]XTRA and [F]AZAN. Tetrahedron Lett 2010; 51:5333-5335. [PMID: 20835363 PMCID: PMC2936105 DOI: 10.1016/j.tetlet.2010.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Improved syntheses of 7-methyl-2-exo-[3'-(2-bromopyridin-3-yl)-5'-pyridinyl]-7-azabicyclo[2.2.1]heptanes (3) and 7-methyl-2-exo-[3'-(6-bromopyridin-2-yl)-5'-pyridinyl]-7-azabicyclo[2.2.1]heptanes (4), precursors for PET radioligands [(18)F]XTRA (1) and [(18)F]AZAN (2), involving a key Stille coupling step followed by deprotection of Boc group and N-methylation are described. The new synthetic procedures provided the title compounds in more than 40% overall yields.
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Affiliation(s)
- Yongjun Gao
- Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, 600 North Wolfe Street, Baltimore, Maryland 21287-0816
| | - Haofan Wang
- Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, 600 North Wolfe Street, Baltimore, Maryland 21287-0816
| | - Ronnie C. Mease
- Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, 600 North Wolfe Street, Baltimore, Maryland 21287-0816
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, 600 North Wolfe Street, Baltimore, Maryland 21287-0816
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Sciences, School of Medicine, Johns Hopkins University, 600 North Wolfe Street, Baltimore, Maryland 21287-0816
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22
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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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23
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Valette H, Xiao Y, Peyronneau MA, Damont A, Kozikowski AP, Wei ZL, Kassiou M, Kellar KJ, Dollé F, Bottlaender M. 18F-ZW-104: A New Radioligand for Imaging Neuronal Nicotinic Acetylcholine Receptors—In Vitro Binding Properties and PET Studies in Baboons. J Nucl Med 2009; 50:1349-55. [DOI: 10.2967/jnumed.108.061374] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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24
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Development of radioligands with optimized imaging properties for quantification of nicotinic acetylcholine receptors by positron emission tomography. Life Sci 2009; 86:575-84. [PMID: 19303028 DOI: 10.1016/j.lfs.2009.02.029] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/05/2009] [Accepted: 02/12/2009] [Indexed: 11/20/2022]
Abstract
AIMS There is an urgent need for positron emission tomography (PET) imaging of the nicotinic acetylcholine receptors (nAChR) to study the role of the nicotinic system in Alzheimer's and Parkinson's diseases, schizophrenia, drug dependence and many other disorders. Greater understanding of the underlying mechanisms of the nicotinic system could direct the development of medications to treat these disorders. Central nAChRs also contribute to a variety of brain functions, including cognition, behavior and memory. MAIN METHODS Currently, only two radiotracers, (S)-3-(azetidin-2-ylmethoxy)-2-[(18)F]fluoropyridine (2-[(18)F]FA) and (S)-5-(azetidin-2-ylmethoxy)-2-[(18)F]fluoropyridine (6-[(18)F]FA), are available for studying nAChRs in human brain using PET. However, the "slow" brain kinetics of these radiotracers hamper mathematical modeling and reliable measurement of kinetic parameters since it takes 4-7 h of PET scanning for the tracers to reach steady state. The imaging drawbacks of the presently available nAChR radioligands have initiated the development of radioligands with faster brain kinetics by several research groups. KEY FINDINGS This minireview attempts to survey the important achievements of several research groups in the discovery of PET nicotinic radioligands reached recently. Specifically, this article reviews papers published from 2006 through 2008 describing the development of fifteen new nAChR (11)C-and (18)F-ligands that show improved imaging properties over 2-[(18)F]FA. SIGNIFICANCE The continuous efforts of radiomedicinal chemists led to the development of several interesting PET radioligands for imaging of nAChR including [(18)F]AZAN, a potentially superior alternative to 2-[(18)F]FA.
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