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Reid GA, Darvesh S. Interaction of exogenous acetylcholinesterase and butyrylcholinesterase with amyloid-β plaques in human brain tissue. Chem Biol Interact 2024; 395:111012. [PMID: 38648920 DOI: 10.1016/j.cbi.2024.111012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/10/2024] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are associated with amyloid-β (Aβ) plaques and exhibit altered biochemical properties in human Alzheimer's disease (AD), as well as in the transgenic 5XFAD mouse model of AD amyloidosis. In the brains of the 5XFAD mouse model devoid of BChE enzyme (5XFAD/BChE-KO), incubation of tissue sections with exogenous BChE purified from human plasma (pl-BChE) leads to its association with Aβ plaques and its biochemical properties are comparable to those reported for endogenous BChE associated with plaques in both human AD and in 5XFAD mouse brain tissue. We sought to determine whether these observations in 5XFAD/BChE-KO mice also apply to human brain tissues. To do so, endogenous ChE activity in human AD brain tissue sections was quenched with 50 % aqueous acetonitrile (MeCNaq) leaving the tissue suitable for further studies. Quenched sections were then incubated with recombinant AChE (r-AChE) or pl-BChE and stained for each enzymes' activity. Exogenous r-AChE or pl-BChE became associated with Aβ plaques, and when bound, had properties that were comparable to the endogenous ChE enzymes associated with plaques in AD brain tissues without acetonitrile treatment. These findings in human AD brain tissue extend previous observations in the 5XFAD/BChE-KO mouse model and demonstrate that exogenously applied r-AChE and pl-BChE have high affinity for Aβ plaques in human brain tissues. This association alters the biochemical properties of these enzymes, most likely due a conformational change. If incorporation of AChE and BChE in Aβ plaques facilitates AD pathogenesis, blocking this association could lead to disease-modifying approaches to AD. This work provides a method to study the mechanism of AChE and BChE interaction with Aβ plaque pathology in post-mortem human brain tissue.
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Affiliation(s)
- G A Reid
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - S Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada; Department of Medicine (Geriatric Medicine and Neurology), Dalhousie University, Halifax, NS, Canada.
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2
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Darvesh S, Banfield S, Dufour M, Forrestall KL, Maillet H, Reid GA, Sands D, Pottie IR. A method for the efficient evaluation of substrate-based cholinesterase imaging probes for Alzheimer's disease. J Enzyme Inhib Med Chem 2023; 38:2225797. [PMID: 38061987 PMCID: PMC10294744 DOI: 10.1080/14756366.2023.2225797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/11/2023] [Accepted: 06/10/2023] [Indexed: 08/16/2023] Open
Abstract
Cholinesterase (ChE) enzymes have been identified as diagnostic markers for Alzheimer disease (AD). Substrate-based probes have been synthesised to detect ChEs but they have not detected changes in ChE distribution associated with AD pathology. Probes are typically screened using spectrophotometric methods with pure enzyme for specificity and kinetics. However, the biochemical properties of ChEs associated with AD pathology are altered. The present work was undertaken to determine whether the Karnovsky-Roots (KR) histochemical method could be used to evaluate probes at the site of pathology. Thirty thioesters and esters were synthesised and evaluated using enzyme kinetic and KR methods. Spectrophotometric methods demonstrated all thioesters were ChE substrates, yet only a few provided staining in the brain with the KR method. Esters were ChE substrates with interactions with brain ChEs. These results suggest that the KR method may provide an efficient means to screen compounds as probes for imaging AD-associated ChEs.
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Affiliation(s)
- Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Medicine (Geriatric Medicine & Neurology), Halifax, Nova Scotia, Canada
- Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada
| | - Scott Banfield
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Maeve Dufour
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Katrina L. Forrestall
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Hillary Maillet
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - G. Andrew Reid
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Dane Sands
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ian R. Pottie
- Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada
- Department of Chemistry, Saint Mary’s University, Halifax, Nova Scotia, Canada
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3
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Mineur YS, Picciotto MR. How can I measure brain acetylcholine levels in vivo? Advantages and caveats of commonly used approaches. J Neurochem 2023; 167:3-15. [PMID: 37621094 PMCID: PMC10616967 DOI: 10.1111/jnc.15943] [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: 06/21/2023] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 08/26/2023]
Abstract
The neurotransmitter acetylcholine (ACh) plays a central role in the regulation of multiple cognitive and behavioral processes, including attention, learning, memory, motivation, anxiety, mood, appetite, and reward. As a result, understanding ACh dynamics in the brain is essential for elucidating the neural mechanisms underlying these processes. In vivo measurements of ACh in the brain have been challenging because of the low concentrations and rapid turnover of this neurotransmitter. Here, we review a number of techniques that have been developed to measure ACh levels in the brain in vivo. We follow this with a deeper focus on use of genetically encoded fluorescent sensors coupled with fiber photometry, an accessible technique that can be used to monitor neurotransmitter release with high temporal resolution and specificity. We conclude with a discussion of methods for analyzing fiber photometry data and their respective advantages and disadvantages. The development of genetically encoded fluorescent ACh sensors is revolutionizing the field of cholinergic signaling, allowing temporally precise measurement of ACh release in awake, behaving animals. Use of these sensors has already begun to contribute to a mechanistic understanding of cholinergic modulation of complex behaviors.
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Affiliation(s)
- Yann S. Mineur
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3 Floor Research, New Haven, CT 06508, USA
| | - Marina R. Picciotto
- Department of Psychiatry, Yale University School of Medicine, 34 Park Street, 3 Floor Research, New Haven, CT 06508, USA
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4
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Sands D, Davis A, Banfield S, Pottie IR, Darvesh S. Solvents and detergents compatible with enzyme kinetic studies of cholinesterases. Chem Biol Interact 2023; 383:110667. [PMID: 37579937 DOI: 10.1016/j.cbi.2023.110667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/02/2023] [Accepted: 08/11/2023] [Indexed: 08/16/2023]
Abstract
Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes that serve a wide range of physiological functions including the hydrolysis of the neurotransmitter acetylcholine and several other xenobiotics. The development of inhibitors for these enzymes has been the focus for the treatment of several conditions, such as Alzheimer's disease. Novel chemical entities are evaluated as potential inhibitors of AChE and BChE using enzyme kinetics. A common issue encountered in these studies is low aqueous solubility of the possible inhibitor. Additives such as cosolvents or detergents can be included in these studies improve the aqueous solubility. Typical cosolvents include acetonitrile or dimethyl sulfoxide while typical detergents include Polysorbate 20 (Tween 20) or 3-((3-cholamidopropyl) dimethylammonio)-1-propanesulfonate (CHAPS). When solubility is not improved, these molecules are often not evaluated further. To address this issue eleven cosolvents and six detergents that could facilitate aqueous solubility were evaluated to understand how they would affect cholinesterase enzymes using Ellman's assay. These studies show that propylene glycol, acetonitrile, methanol, Tween 20, Polysorbate 80 (Tween 80), polyoxyethylene 23 lauryl ether (Brij 35) and polyoxyethylene 10 oleoyl ether (Brij 96v) have the least inhibitory effects towards cholinesterase activity. It is concluded that these cosolvents and detergents should be considered as solubilizing agents for evaluation of potential cholinesterase inhibitors with low aqueous solubility.
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Affiliation(s)
- Dane Sands
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrew Davis
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Scott Banfield
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ian R Pottie
- Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Chemistry and Physics, Mount St. Vincent University, Halifax, Nova Scotia, Canada; Department of Medicine (Geriatric Medicine & Neurology), Halifax, Nova Scotia, Canada.
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5
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Gil-Rivas A, de Pascual-Teresa B, Ortín I, Ramos A. New Advances in the Exploration of Esterases with PET and Fluorescent Probes. Molecules 2023; 28:6265. [PMID: 37687094 PMCID: PMC10488407 DOI: 10.3390/molecules28176265] [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: 07/28/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023] Open
Abstract
Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.
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Affiliation(s)
- Alba Gil-Rivas
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Beatriz de Pascual-Teresa
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Irene Ortín
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
| | - Ana Ramos
- Departamento de Química y Bioquímica, Facultad de Farmacia, Universidad San Pablo-CEU, CEU Universities, Urbanización Montepríncipe, 28668 Boadilla del Monte, Spain
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6
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Dávila G, Torres-Prioris MJ, López-Barroso D, Berthier ML. Turning the Spotlight to Cholinergic Pharmacotherapy of the Human Language System. CNS Drugs 2023; 37:599-637. [PMID: 37341896 PMCID: PMC10374790 DOI: 10.1007/s40263-023-01017-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 06/22/2023]
Abstract
Even though language is essential in human communication, research on pharmacological therapies for language deficits in highly prevalent neurodegenerative and vascular brain diseases has received little attention. Emerging scientific evidence suggests that disruption of the cholinergic system may play an essential role in language deficits associated with Alzheimer's disease and vascular cognitive impairment, including post-stroke aphasia. Therefore, current models of cognitive processing are beginning to appraise the implications of the brain modulator acetylcholine in human language functions. Future work should be directed further to analyze the interplay between the cholinergic system and language, focusing on identifying brain regions receiving cholinergic innervation susceptible to modulation with pharmacotherapy to improve affected language domains. The evaluation of language deficits in pharmacological cholinergic trials for Alzheimer's disease and vascular cognitive impairment has thus far been limited to coarse-grained methods. More precise, fine-grained language testing is needed to refine patient selection for pharmacotherapy to detect subtle deficits in the initial phases of cognitive decline. Additionally, noninvasive biomarkers can help identify cholinergic depletion. However, despite the investigation of cholinergic treatment for language deficits in Alzheimer's disease and vascular cognitive impairment, data on its effectiveness are insufficient and controversial. In the case of post-stroke aphasia, cholinergic agents are showing promise, particularly when combined with speech-language therapy to promote trained-dependent neural plasticity. Future research should explore the potential benefits of cholinergic pharmacotherapy in language deficits and investigate optimal strategies for combining these agents with other therapeutic approaches.
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Affiliation(s)
- Guadalupe Dávila
- Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias, University of Malaga, Marqués de Beccaria 3, 29010, Malaga, Spain
- Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain
- Department of Psychobiology and Methodology of Behavioral Sciences, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
- Language Neuroscience Research Laboratory, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
| | - María José Torres-Prioris
- Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias, University of Malaga, Marqués de Beccaria 3, 29010, Malaga, Spain
- Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain
- Department of Psychobiology and Methodology of Behavioral Sciences, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
- Language Neuroscience Research Laboratory, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
| | - Diana López-Barroso
- Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias, University of Malaga, Marqués de Beccaria 3, 29010, Malaga, Spain
- Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain
- Department of Psychobiology and Methodology of Behavioral Sciences, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
- Language Neuroscience Research Laboratory, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain
| | - Marcelo L Berthier
- Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias, University of Malaga, Marqués de Beccaria 3, 29010, Malaga, Spain.
- Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain.
- Language Neuroscience Research Laboratory, Faculty of Psychology and Speech Therapy, University of Malaga, Malaga, Spain.
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7
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Spatial topography of the basal forebrain cholinergic projections: Organization and vulnerability to degeneration. HANDBOOK OF CLINICAL NEUROLOGY 2021; 179:159-173. [PMID: 34225960 DOI: 10.1016/b978-0-12-819975-6.00008-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The basal forebrain (BF) cholinergic system constitutes a heterogeneous cluster of large projection neurons that innervate the entire cortical mantle and amygdala. Cholinergic neuromodulation plays a critical role in regulating cognition and behavior, as well as maintenance of cellular homeostasis. Decades of postmortem histology research have demonstrated that the BF cholinergic neurons are selectively vulnerable to aging and age-related neuropathology in degenerative diseases such as Alzheimer's and Parkinson's diseases. Emerging evidence from in vivo neuroimaging research, which permits longitudinal tracking of at-risk individuals, indicates that cholinergic neurodegeneration might play an earlier and more pivotal role in these diseases than was previously appreciated. Despite these advances, our understanding of the organization and functions of the BF cholinergic system mostly derives from nonhuman animal research. In this chapter, we begin with a review of the topographical organization of the BF cholinergic system in rodent and nonhuman primate models. We then discuss basic and clinical neuroscience research in humans, which has started to translate and extend the nonhuman animal research using novel noninvasive neuroimaging techniques. We focus on converging evidence indicating that the selective vulnerability of cholinergic neurons in Alzheimer's and Parkinson's diseases is expressed along a rostral-caudal topography in the BF. We close with a discussion of why this topography of vulnerability in the BF may occur and why it is relevant to the clinician.
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8
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Meena VK, Chaturvedi S, Sharma RK, Mishra AK, Hazari PP. Potent Acetylcholinesterase Selective and Reversible Homodimeric Agent Based on Tacrine for Theranostics. Mol Pharm 2019; 16:2296-2308. [DOI: 10.1021/acs.molpharmaceut.8b01058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Virendra Kumar Meena
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig S.K. Mazumdar Road, Delhi 110054, India
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig S.K. Mazumdar Road, Delhi 110054, India
| | | | - Anil Kumar Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Puja Panwar Hazari
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Brig S.K. Mazumdar Road, Delhi 110054, India
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9
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Okada M. [12. Metabolite Analysis for Development and Quantification of Molecular Imaging Probes]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 75:71-79. [PMID: 30662035 DOI: 10.6009/jjrt.2019_jsrt_75.1.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
- Maki Okada
- National Institute of Radiological Sciences National Institutes for Quantum and Radiological Science and Technology
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10
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Abstract
Hydrolytic enzymes are a large class of biological catalysts that play a vital role in a plethora of critical biochemical processes required to maintain human health. However, the expression and/or activity of these important enzymes can change in many different diseases and therefore represent exciting targets for the development of positron emission tomography (PET) and single-photon emission computed tomography (SPECT) radiotracers. This review focuses on recently reported radiolabeled substrates, reversible inhibitors, and irreversible inhibitors investigated as PET and SPECT tracers for imaging hydrolytic enzymes. By learning from the most successful examples of tracer development for hydrolytic enzymes, it appears that an early focus on careful enzyme kinetics and cell-based studies are key factors for identifying potentially useful new molecular imaging agents.
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Affiliation(s)
- Brian P Rempel
- 1 Department of Science, Augustana Faculty, University of Alberta, Edmonton, Alberta, Canada
| | - Eric W Price
- 2 Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Christopher P Phenix
- 2 Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.,3 Biomarker Discovery, Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
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11
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3-(Benzyloxy)-1-(5-[18F]fluoropentyl)-5-nitro-1H-indazole: a PET radiotracer to measure acetylcholinesterase in brain. Future Med Chem 2017. [DOI: 10.4155/fmc-2017-0023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Aim: Noninvasive studies of the acetylcholinesterase (AChE) level in Alzheimer's disease (AD) patients can contribute to a better understanding of the disease and its therapeutic. We propose 3-(benzyloxy)-1-(5-[18F]fluoropentyl)-5-nitro-1H-indazole, [18F]-IND1, structurally related to the AChE-inhibitor CP126,998, as a new positron emission tomography-radiotracer. Experimental: Radiosynthesis, with 18F, stability, lipophilicity and protein binding of [18F]-IND1 were studied. In vivo behavior, in normal mice and on AD mice models, were also analyzed. Results: [18F]-IND1 was obtained in good radiochemical yield, was stable for at least 2 h in different conditions, and had adequate lipophilicity for blood–brain barrier penetration. Biodistribution studies, in normal mice, showed that [18F]-IND1 was retained in the brain after 1 h. In vivo tacrine-blocking experiments indicated this uptake could be specifically due to AChE interaction. Studies in transgenic AD mice showed differential, compared with normal mice, binding in many brain regions. Conclusion: [18F]-IND1 can be used to detect AChE changes in AD patients.
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12
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Amyloid imaging: Past, present and future perspectives. Ageing Res Rev 2016; 30:95-106. [PMID: 26827784 DOI: 10.1016/j.arr.2016.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 11/23/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, and tau neurofibrillary tangles, along dendritic and synaptic loss and reactive gliosis. Functional and molecular neuroimaging techniques such as positron emission tomography (PET) using functional and molecular tracers, in conjuction with other Aβ and tau biomarkers in CSF, are proving valuable in the differential diagnosis of AD, as well as in establishing disease prognosis. With the advent of new therapeutic strategies, there has been an increasing application of these techniques for the determination of Aβ burden in vivo in the patient selection, evaluation of target engagement and assessment of the efficacy of therapeutic approaches aimed at reducing Aβ in the brain.
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13
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Jollymore-Hughes CT, Pottie IR, Martin E, Rosenberry TL, Darvesh S. Development of acetophenone ligands as potential neuroimaging agents for cholinesterases. Bioorg Med Chem 2016; 24:5270-5279. [PMID: 27637382 DOI: 10.1016/j.bmc.2016.08.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/22/2016] [Accepted: 08/26/2016] [Indexed: 10/21/2022]
Abstract
Association of cholinesterase with β-amyloid plaques and tau neurofibrillary tangles in Alzheimer's disease offers an opportunity to detect disease pathology during life. Achieving this requires development of radiolabelled cholinesterase ligands with high enzyme affinity. Various fluorinated acetophenone derivatives bind to acetylcholinesterase with high affinity, including 2,2,2-trifluoro-1-(3-dimethylaminophenyl)ethanone (1) and 1-(3-tert-butylphenyl)-2,2,2-trifluoroethanone (2). Such compounds also offer potential for incorporation of radioactive fluorine (18F) for Positron Emission Tomography (PET) imaging of cholinesterases in association with Alzheimer's disease pathology in the living brain. Here we describe the synthesis of two meta-substituted chlorodifluoroacetophenones using a Weinreb amide strategy and their rapid conversion to the corresponding trifluoro derivatives through nucleophilic substitution by fluoride ion, in a reaction amenable to incorporating 18F for PET imaging. In vitro kinetic analysis indicates tight binding of the trifluoro derivatives to cholinesterases. Compound 1 has a Ki value of 7nM for acetylcholinesterase and 1300nM for butyrylcholinesterase while for compound 2 these values are 0.4nM and 26nM, respectively. Tight binding of these compounds to cholinesterase encourages their development for PET imaging detection of cholinesterase associated with Alzheimer's disease pathology.
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Affiliation(s)
| | - Ian R Pottie
- Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Earl Martin
- Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada
| | | | - Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada; Department of Medicine (Neurology and Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada.
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14
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Sawatzky E, Al-Momani E, Kobayashi R, Higuchi T, Samnick S, Decker M. A Novel Way To Radiolabel Human Butyrylcholinesterase for Positron Emission Tomography through Irreversible Transfer of the Radiolabeled Moiety. ChemMedChem 2016; 11:1540-50. [DOI: 10.1002/cmdc.201600223] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 05/30/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Edgar Sawatzky
- Pharmaceutical and Medicinal Chemistry; Institute of Pharmacy and Food Chemistry; Julius Maximilian University Würzburg; Am Hubland 97074 Würzburg Germany
| | - Ehab Al-Momani
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Ryohei Kobayashi
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Takahiro Higuchi
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Samuel Samnick
- Experimental Nuclear Medicine; Center of Inner Medicine; University Hospital Würzburg; OberdürrbacherStrasse 6 97080 Würzburg Germany
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry; Institute of Pharmacy and Food Chemistry; Julius Maximilian University Würzburg; Am Hubland 97074 Würzburg Germany
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15
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Brooks AF, Shao X, Quesada CA, Sherman P, Scott PJH, Kilbourn MR. In Vivo Metabolic Trapping Radiotracers for Imaging Monoamine Oxidase-A and -B Enzymatic Activity. ACS Chem Neurosci 2015; 6:1965-71. [PMID: 26393369 DOI: 10.1021/acschemneuro.5b00223] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The isozymes of monoamine oxidase (MAO-A and MAO-B) are important enzymes involved in the metabolism of numerous biogenic amines, including the neurotransmitters serotonin, dopamine, and norepinephrine. Recently, changes in concentrations of MAO-B have been proposed to be an in vivo marker of neuroinflammation associated with Alzheimer's disease. Previous developments of in vivo radiotracers for imaging changes in MAO enzyme expression or activity have utilized the irreversible propargylamine-based suicide inhibitors or high-affinity reversibly binding inhibitors. As an alternative approach, we have investigated 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines as metabolic trapping agents for the monoamine oxidases. MAO-mediated oxidation and spontaneous hydrolysis yield 1-[(11)C]methyl-2,3-dihydro-4-pyridinone as a hydrophilic metabolite that is trapped within brain tissues. Radiotracers with phenyl, biphenyl, and 7-coumarinyl ethers were evaluated using microPET imaging in rat and primate brains. No isozyme selectivity for radiotracer trapping was observed in the rat brain for any compound, but in the monkey brain, the phenyl ether demonstrated MAO-A selectivity and the coumarinyl ether showed MAO-B selectivity. These are lead compounds for further development of 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines with optimized brain pharmacokinetics and isozyme selectivity.
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Affiliation(s)
- Allen F. Brooks
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Xia Shao
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
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16
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Macdonald IR, Reid GA, Pottie IR, Martin E, Darvesh S. Synthesis and Preliminary Evaluation of Phenyl 4-123I-Iodophenylcarbamate for Visualization of Cholinesterases Associated with Alzheimer Disease Pathology. J Nucl Med 2015; 57:297-302. [PMID: 26541777 DOI: 10.2967/jnumed.115.162032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 10/21/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Acetylcholinesterase and butyrylcholinesterase accumulate with brain β-amyloid (Aβ) plaques in Alzheimer disease (AD). The overall activity of acetylcholinesterase is found to decline in AD, whereas butyrylcholinesterase has been found to either increase or remain the same. Although some cognitively normal older adults also have Aβ plaques within the brain, cholinesterase-associated plaques are generally less abundant in such individuals. Thus, brain imaging of cholinesterase activity associated with Aβ plaques has the potential to distinguish AD from cognitively normal older adults, with or without Aβ accumulation, during life. Current Aβ imaging agents are not able to provide this distinction. To address this unmet need, synthesis and evaluation of a cholinesterase-binding ligand, phenyl 4-(123)I-iodophenylcarbamate ((123)I-PIP), is described. METHODS Phenyl 4-iodophenylcarbamate was synthesized and evaluated for binding potency toward acetylcholinesterase and butyrylcholinesterase using enzyme kinetic analysis. This compound was subsequently rapidly radiolabeled with (123)I and purified by high-performance liquid chromatography. Autoradiographic analyses were performed with (123)I-PIP using postmortem orbitofrontal cortex from cognitively normal and AD human brains. Comparisons were made with an Aβ imaging agent, 2-(4'-dimethylaminophenyl)-6-(123)I-iodo-imidazo[1,2-a]pyridine ((123)I-IMPY), in adjacent brain sections. Tissues were also stained for Aβ and cholinesterase activity to visualize Aβ plaque load for comparison with radioligand uptake. RESULTS Synthesized and purified PIP exhibited binding to cholinesterases. (123)I was successfully incorporated into this ligand. (123)I-PIP autoradiography with human tissue revealed accumulation of radioactivity only in AD brain tissues in which Aβ plaques had cholinesterase activity. (123)I-IMPY accumulated in brain tissues with Aβ plaques from both AD and cognitively normal individuals. CONCLUSION Radiolabeled ligands specific for cholinesterases have potential for use in neuroimaging AD plaques during life. The compound herein described, (123)I-PIP, can detect cholinesterases associated with Aβ plaques and can distinguish AD brain tissues from those of cognitively normal older adults with Aβ plaques. Imaging cholinesterase activity associated with Aβ plaques in the living brain may contribute to the definitive diagnosis of AD during life.
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Affiliation(s)
- Ian R Macdonald
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - G Andrew Reid
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ian R Pottie
- Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada; and
| | - Earl Martin
- Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada
| | - Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, Nova Scotia, Canada Department of Medicine (Neurology and Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada
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17
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Liu H, Jin H, Li J, Zhang X, Kaneshige K, Parsons SM, Perlmutter JS, Tu Z. In vitro and ex vivo characterization of (-)-TZ659 as a ligand for imaging the vesicular acetylcholine transporter. Eur J Pharmacol 2015; 752:18-25. [PMID: 25678250 PMCID: PMC4369186 DOI: 10.1016/j.ejphar.2015.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/30/2015] [Accepted: 02/03/2015] [Indexed: 12/30/2022]
Abstract
The loss of cholinergic neurons and synapses relates to the severity of dementia in several neurodegenerative pathologies; and the vesicular acetylcholine transporter (VAChT) provides a reliable biomarker of cholinergic function. We recently characterized and (11)C-labeled a new VAChT inhibitor, (-)-TZ659. Here we report the in vitro and ex vivo characterization of (-)-TZ659. A stably transfected PC12(A123.7) cell line which expresses human VAChT (hVAChT) was used for the in vitro binding characterization of (-)-[(3)H]TZ659. A saturated binding curve was obtained with Kd=1.97±0.30nM and Bmax=3240±145.9fmol/mg protein. In comparison, a PC12(A123.7) cell line that expresses mutant hVAChT showed decreased binding affinity (Kd=15.94±0.28nM). Competitive binding assays using a panel of other CNS ligands showed no inhibition of (-)-[(3)H]TZ659 binding. On the other hand, binding inhibitions were observed only using VAChT inhibitors (Ki=0.20-31.35nM). An in vitro assay using rat brain homogenates showed that (-)-[(3)H]TZ659 had higher binding in striatum than in cerebellum, with a target: non-target ratio>3.46. Even higher ex vivo striatum-to-cerebellum ratios (9.56±1.11) were observed using filtered homogenates of brain tissue after rats were injected intravenously with (-)-[(11)C]TZ659. Ex vivo autoradiography of (-)-[(11)C]TZ659 confirmed high striatal uptake, with a consistently high striatum-to-cerebellum ratio (2.99±0.44). In conclusion, (-)-TZ659 demonstrated high potency and good specificity for VAChT in vitro and in vivo. These data suggest that (-)-[(11)C]TZ659 may be a promising PET tracer to image VAChT in the brain.
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Affiliation(s)
- Hui Liu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hongjun Jin
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Junfeng Li
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xiang Zhang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kota Kaneshige
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Stanley M Parsons
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, USA
| | - Joel S Perlmutter
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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18
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Macdonald IR, DeBay DR, Reid GA, O'Leary TP, Jollymore CT, Mawko G, Burrell S, Martin E, Bowen CV, Brown RE, Darvesh S. Early detection of cerebral glucose uptake changes in the 5XFAD mouse. Curr Alzheimer Res 2015; 11:450-60. [PMID: 24801216 PMCID: PMC4082185 DOI: 10.2174/1567205011666140505111354] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 04/13/2014] [Accepted: 04/15/2014] [Indexed: 01/06/2023]
Abstract
Brain glucose hypometabolism has been observed in Alzheimer’s disease (AD) patients, and is detected with 18F radiolabelled glucose, using positron emission tomography. A pathological hallmark of AD is deposition of brain β-amyloid plaques that may influence cerebral glucose metabolism. The five times familial AD (5XFAD) mouse is a model of brain amyloidosis exhibiting AD-like phenotypes. This study examines brain β-amyloid plaque deposition and 18FDG uptake, to search for an early biomarker distinguishing 5XFAD from wild-type mice. Thus, brain 18FDG uptake and plaque deposition was studied in these mice at age 2, 5 and 13 months. The 5XFAD mice demonstrated significantly reduced brain 18FDG uptake at 13 months relative to wild-type controls but not in younger mice, despite substantial β-amyloid plaque deposition. However, by comparing the ratio of uptake values for glucose in different regions in the same brain, 5XFAD mice could be distinguished from controls at age 2 months. This method of measuring altered glucose metabolism may represent an early biomarker for the progression of amyloid deposition in the brain. We conclude that brain 18FDG uptake can be a sensitive biomarker for early detection of abnormal metabolism in the 5XFAD mouse when alternative relative uptake values are utilized.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - S Darvesh
- Room 1308, Camp Hill Veterans' Memorial, 5955 Veterans' Memorial Lane, Halifax, Nova Scotia, B3H 2E1. Canada.
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19
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Gjerløff T, Jakobsen S, Nahimi A, Munk OL, Bender D, Alstrup AKO, Vase KH, Hansen SB, Brooks DJ, Borghammer P. In vivo imaging of human acetylcholinesterase density in peripheral organs using 11C-donepezil: dosimetry, biodistribution, and kinetic analyses. J Nucl Med 2014; 55:1818-24. [PMID: 25324520 DOI: 10.2967/jnumed.114.143859] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Brain cholinergic function has been previously studied with PET but little effort has been devoted to imaging peripheral organs. Many disorders, including diabetes and Parkinson disease, are associated with autonomic dysfunction including parasympathetic denervation. Nonneuronal cholinergic signaling is also involved in immune responses to infections and in cancer pathogenesis. 5-(11)C-methoxy-donepezil, a noncompetitive acetylcholinesterase ligand, was previously validated for imaging cerebral levels of acetylcholinesterase. In the present study, we explored the utility of (11)C-donepezil for imaging acetylcholinesterase densities in peripheral organs, including the salivary glands, heart, stomach, intestine, pancreas, liver, and spleen. METHODS With autoradiography, we determined binding affinities and levels of nonspecific (11)C-donepezil binding to porcine tissues. Radiation dosimetry was estimated by whole-body PET of a single human volunteer. Biodistribution and kinetic analyses of (11)C-donepezil time-activity curves were assessed with dynamic PET scans of 6 healthy human volunteers. A single pig with bacterial abscesses was PET-scanned to explore (11)C-donepezil uptake in infections. RESULTS Autoradiography showed high (11)C-donepezil binding (dissociation constant, 6-39 nM) in pig peripheral organs with low nonspecific signal. Radiation dosimetry was favorable (effective dose, 5.2 μSv/MBq). Peripheral metabolization of (11)C-donepezil was low (>90% unchanged ligand at 60 min). Slow washout kinetics were seen in the salivary glands, heart, intestines, pancreas, and prostate. A linear correlation was seen between (11)C-donepezil volumes of distribution and standardized uptake values, suggesting that arterial blood sampling may not be necessary for modeling uptake kinetics in future (11)C-donepezil PET studies. High standardized uptake values and slow washout kinetics were seen in bacterial abscesses. CONCLUSION (11)C-donepezil PET is suitable for imaging acetylcholinesterase densities in peripheral organs. Its uptake may potentially be quantitated with static whole-body PET scans not requiring arterial blood sampling. We also demonstrated high (11)C-donepezil binding in bacterial abscesses. We propose that (11)C-donepezil PET imaging may be able to quantify the parasympathetic innervation of organs but also detect nonneuronal cholinergic activity in infections.
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Affiliation(s)
- Trine Gjerløff
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Steen Jakobsen
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Adjmal Nahimi
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Ole L Munk
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Dirk Bender
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Aage K O Alstrup
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Karina H Vase
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - Søren B Hansen
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
| | - David J Brooks
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and Department of Medicine, Imperial College London, London, United Kingdom
| | - Per Borghammer
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark; and
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20
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Holland JP, Liang SH, Rotstein BH, Collier TL, Stephenson NA, Greguric I, Vasdev N. Alternative approaches for PET radiotracer development in Alzheimer's disease: imaging beyond plaque. J Labelled Comp Radiopharm 2013; 57:323-31. [PMID: 24327420 DOI: 10.1002/jlcr.3158] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/29/2013] [Indexed: 12/18/2022]
Abstract
Alzheimer's disease (AD) and related dementias show increasing clinical prevalence, yet our understanding of the etiology and pathobiology of disease-related neurodegeneration remains limited. In this regard, noninvasive imaging with radiotracers for positron emission tomography (PET) presents a unique tool for quantifying spatial and temporal changes in characteristic biological markers of brain disease and for assessing potential drug efficacy. PET radiotracers targeting different protein markers are being developed to address questions pertaining to the molecular and/or genetic heterogeneity of AD and related dementias. For example, radiotracers including [(11) C]-PiB and [(18) F]-AV-45 (Florbetapir) are being used to measure the density of Aβ-plaques in AD patients and to interrogate the biological mechanisms of disease initiation and progression. Our focus is on the development of novel PET imaging agents, targeting proteins beyond Aβ-plaques, which can be used to investigate the broader mechanism of AD pathogenesis. Here, we present the chemical basis of various radiotracers which show promise in preclinical or clinical studies for use in evaluating the phenotypic or biochemical characteristics of AD. Radiotracers for PET imaging neuroinflammation, metal ion association with Aβ-plaques, tau protein, cholinergic and cannabinoid receptors, and enzymes including glycogen-synthase kinase-3β and monoamine oxidase B amongst others, and their connection to AD are highlighted.
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Affiliation(s)
- Jason P Holland
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Department of Radiology, Harvard Medical School, 55 Fruit St., White 427, Boston, Massachusetts, 02114, USA; Life Sciences, Australian Nuclear Science and Technology Organisation, Kirrawee, New South Wales, 2232, Australia
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