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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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Jackson IM, Lee SJ, Sowa AR, Rodnick ME, Bruton L, Clark M, Preshlock S, Rothley J, Rogers VE, Botti LE, Henderson BD, Hockley BG, Torres J, Raffel DM, Brooks AF, Frey KA, Kilbourn MR, Koeppe RA, Shao X, Scott PJH. Use of 55 PET radiotracers under approval of a Radioactive Drug Research Committee (RDRC). EJNMMI Radiopharm Chem 2020; 5:24. [PMID: 33175263 PMCID: PMC7658275 DOI: 10.1186/s41181-020-00110-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/19/2020] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND In the US, EU and elsewhere, basic clinical research studies with positron emission tomography (PET) radiotracers that are generally recognized as safe and effective (GRASE) can often be conducted under institutional approval. For example, in the United States, such research is conducted under the oversight of a Radioactive Drug Research Committee (RDRC) as long as certain requirements are met. Firstly, the research must be for basic science and cannot be intended for immediate therapeutic or diagnostic purposes, or to determine the safety and effectiveness of the PET radiotracer. Secondly, the PET radiotracer must be generally recognized as safe and effective. Specifically, the mass dose to be administered must not cause any clinically detectable pharmacological effect in humans, and the radiation dose to be administered must be the smallest dose practical to perform the study and not exceed regulatory dose limits within a 1-year period. In our experience, the main barrier to using a PET radiotracer under RDRC approval is accessing the required information about mass and radioactive dosing. RESULTS The University of Michigan (UM) has a long history of using PET radiotracers in clinical research studies. Herein we provide dosing information for 55 radiotracers that will enable other PET Centers to use them under the approval of their own RDRC committees. CONCLUSIONS The data provided herein will streamline future RDRC approval, and facilitate further basic science investigation of 55 PET radiotracers that target functionally relevant biomarkers in high impact disease states.
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Affiliation(s)
- Isaac M Jackson
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
- Present Address: Stanford University, Stanford, CA, USA
| | - So Jeong Lee
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
- Present Address: Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Alexandra R Sowa
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Melissa E Rodnick
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Laura Bruton
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Mara Clark
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Sean Preshlock
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Jill Rothley
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Virginia E Rogers
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Leslie E Botti
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Bradford D Henderson
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Brian G Hockley
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Jovany Torres
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - David M Raffel
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Allen F Brooks
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Kirk A Frey
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Michael R Kilbourn
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Robert A Koeppe
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Xia Shao
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan, 2276 Medical Science Bldg I, SPC 5610, Ann Arbor, MI, 48109, USA.
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Rutin restores neurobehavioral deficits via alterations in cadmium bioavailability in the brain of rats exposed to cadmium. Neurotoxicology 2020; 77:12-19. [DOI: 10.1016/j.neuro.2019.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 11/27/2019] [Accepted: 12/09/2019] [Indexed: 12/17/2022]
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Albin RL, Bohnen NI, Muller MLTM, Dauer WT, Sarter M, Frey KA, Koeppe RA. Regional vesicular acetylcholine transporter distribution in human brain: A [ 18 F]fluoroethoxybenzovesamicol positron emission tomography study. J Comp Neurol 2018; 526:2884-2897. [PMID: 30255936 DOI: 10.1002/cne.24541] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/07/2018] [Accepted: 09/10/2018] [Indexed: 12/21/2022]
Abstract
Prior efforts to image cholinergic projections in human brain in vivo had significant technical limitations. We used the vesicular acetylcholine transporter (VAChT) ligand [18 F]fluoroethoxybenzovesamicol ([18 F]FEOBV) and positron emission tomography to determine the regional distribution of VAChT binding sites in normal human brain. We studied 29 subjects (mean age 47 [range 20-81] years; 18 men; 11 women). [18 F]FEOBV binding was highest in striatum, intermediate in the amygdala, hippocampal formation, thalamus, rostral brainstem, some cerebellar regions, and lower in other regions. Neocortical [18 F]FEOBV binding was inhomogeneous with relatively high binding in insula, BA24, BA25, BA27, BA28, BA34, BA35, pericentral cortex, and lowest in BA17-19. Thalamic [18 F]FEOBV binding was inhomogeneous with greatest binding in the lateral geniculate nuclei and relatively high binding in medial and posterior thalamus. Cerebellar cortical [18 F]FEOBV binding was high in vermis and flocculus, and lower in the lateral cortices. Brainstem [18 F]FEOBV binding was most prominent at the mesopontine junction, likely associated with the pedunculopontine-laterodorsal tegmental complex. Significant [18 F]FEOBV binding was present throughout the brainstem. Some regions, including the striatum, primary sensorimotor cortex, and anterior cingulate cortex exhibited age-related decreases in [18 F]FEOBV binding. These results are consistent with prior studies of cholinergic projections in other species and prior postmortem human studies. There is a distinctive pattern of human neocortical VChAT expression. The patterns of thalamic and cerebellar cortical cholinergic terminal distribution are likely unique to humans. Normal aging is associated with regionally specific reductions in [18 F]FEOBV binding in some cortical regions and the striatum.
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Affiliation(s)
- Roger L Albin
- Neurology Service & GRECC, VAAAHS, Ann Arbor, Michigan.,Department of Neurology, University of Michigan, Ann Arbor, Michigan.,University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Michigan Alzheimer Disease Center, Ann Arbor, Michigan
| | - Nicolaas I Bohnen
- Neurology Service & GRECC, VAAAHS, Ann Arbor, Michigan.,Department of Neurology, University of Michigan, Ann Arbor, Michigan.,University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Martijn L T M Muller
- University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - William T Dauer
- Neurology Service & GRECC, VAAAHS, Ann Arbor, Michigan.,Department of Neurology, University of Michigan, Ann Arbor, Michigan.,University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan
| | - Martin Sarter
- University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Department of Psychology, University of Michigan, Ann Arbor, Michigan
| | - Kirk A Frey
- Department of Neurology, University of Michigan, Ann Arbor, Michigan.,Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Robert A Koeppe
- University of Michigan Morris K. Udall Center of Excellence for Research in Parkinson's Disease, Ann Arbor, Michigan.,Department of Radiology, University of Michigan, Ann Arbor, Michigan
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Macdonald IR, Maxwell SP, Reid GA, Cash MK, DeBay DR, Darvesh S. Quantification of Butyrylcholinesterase Activity as a Sensitive and Specific Biomarker of Alzheimer's Disease. J Alzheimers Dis 2018; 58:491-505. [PMID: 28453492 PMCID: PMC5438481 DOI: 10.3233/jad-170164] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Amyloid-β (Aβ) plaques are a neuropathological hallmark of Alzheimer’s disease (AD); however, a significant number of cognitively normal older adults can also have Aβ plaques. Thus, distinguishing AD from cognitively normal individuals with Aβ plaques (NwAβ) based on Aβ plaque detection is challenging. It has been observed that butyrylcholinesterase (BChE) accumulates in plaques preferentially in AD. Thus, detecting BChE-associated plaques has the potential as an improved AD biomarker. We present Aβ, thioflavin-S, and BChE quantification of 26 postmortem brain tissues; AD (n = 8), NwAβ (n = 6), cognitively normal without plaques (n = 8), and other common dementias including corticobasal degeneration, frontotemporal dementia with tau, dementia with Lewy bodies, and vascular dementia. Pathology burden in the orbitofrontal cortex, entorhinal cortex, amygdala, and hippocampal formation was determined and compared. The predictive value of Aβ and BChE quantification was determined, via receiver-operating characteristic plots, to evaluate their AD diagnostic performance using sensitivity, specificity, and area under curve (AUC) metrics. In general, Aβ and BChE-associated pathology were greater in AD, particularly in the orbitofrontal cortex. In this region, the largest increase (9.3-fold) was in BChE-associated pathology, observed between NwAβ and AD, due to the virtual absence of BChE-associated plaques in NwAβ brains. Furthermore, BChE did not associate with pathology of the other dementias. In this sample, BChE-associated pathology provided better diagnostic performance (AUC = 1.0, sensitivity/specificity = 100% /100%) when compared to Aβ (AUC = 0.98, 100% /85.7%). These findings highlight the predictive value of BChE as a biomarker for AD that could facilitate timely disease diagnosis and management.
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Affiliation(s)
- Ian R Macdonald
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Selena P Maxwell
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - George A Reid
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Meghan K Cash
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Drew R DeBay
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, NS, Canada.,Department of Medicine (Neurology and Geriatric Medicine), Dalhousie University, Halifax, NS, Canada.,Department of Chemistry and Physics, Mount Saint Vincent University, Halifax, NS, Canada
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Targeting butyrylcholinesterase for preclinical single photon emission computed tomography (SPECT) imaging of Alzheimer's disease. ALZHEIMERS & DEMENTIA-TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2017; 3:166-176. [PMID: 29067326 PMCID: PMC5651425 DOI: 10.1016/j.trci.2017.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
INTRODUCTION Diagnosis of Alzheimer's disease (AD) in vivo, by molecular imaging of amyloid or tau, is constrained because similar changes can be found in brains of cognitively normal individuals. Butyrylcholinesterase (BChE), which becomes associated with these structures in AD, could elevate the accuracy of AD diagnosis by focusing on BChE pathology in the cerebral cortex, a region of scant BChE activity in healthy brain. METHODS N-methylpiperidin-4-yl 4-[123I]iodobenzoate, a BChE radiotracer, was injected intravenously into B6SJL-Tg(APPSwFlLon, PSEN1∗M146 L∗L286 V) 6799Vas/Mmjax (5XFAD) mice and their wild-type (WT) counterparts for comparative single photon emission computed tomography (SPECT) studies. SPECT, computed tomography (CT), and magnetic resonance imaging (MRI) enabled comparison of whole brain and regional retention of the BChE radiotracer in both mouse strains. RESULTS Retention of the BChE radiotracer was consistently higher in the 5XFAD mouse than in WT, and differences were particularly evident in the cerebral cortex. DISCUSSION Cerebral cortical BChE imaging with SPECT can distinguish 5XFAD mouse model from the WT counterpart.
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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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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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Hockley BG, Stewart MN, Sherman P, Quesada C, Kilbourn MR, Albin RL, Scott PJH. (-)-[(18) F]Flubatine: evaluation in rhesus monkeys and a report of the first fully automated radiosynthesis validated for clinical use. J Labelled Comp Radiopharm 2013; 56:595-9. [PMID: 24285235 DOI: 10.1002/jlcr.3069] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Revised: 05/09/2013] [Accepted: 05/12/2013] [Indexed: 11/10/2022]
Abstract
(-)-[(18) F]Flubatine was selected for clinical imaging of α4 β2 nicotinic acetylcholine receptors because of its high affinity and appropriate kinetic profile. A fully automated synthesis of (-)-[(18) F]flubatine as a sterile isotonic solution suitable for clinical use is reported, as well as the first evaluation in nonhuman primates (rhesus macaques). (-)-[(18) F]Flubatine was prepared by fluorination of the Boc-protected trimethylammonium iodide precursor with [(18) F]fluoride in an automated synthesis module. Subsequent deprotection of the Boc group with 1-M HCl yielded (-)-[(18) F]flubatine, which was purified by semi-preparative HPLC. (-)-[(18) F]Flubatine was prepared in 25% radiochemical yield (formulated for clinical use at end of synthesis, n = 3), >95% radiochemical purity, and specific activity = 4647 Ci/mmol (171.9 GBq/µmol). Doses met all quality control criteria confirming their suitability for clinical use. Evaluation of (-)-[(18) F]flubatine in rhesus macaques was performed with a Concorde MicroPET P4 scanner (Concorde MicroSystems, Knoxville, TN). The brain was imaged for 90 min, and data were reconstructed using the 3-D maximum a posteriori algorithm. Image analysis revealed higher uptake and slower washout in the thalamus than those in other areas of the brain and peak uptake at 45 min. Injection of 2.5 µg/kg of nifene at 60 min initiated a slow washout of [(18) F]flubatine, with about 25% clearance from the thalamus by the end of imaging at 90 min.
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Affiliation(s)
- Brian G Hockley
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI, USA
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Chaiyana W, Schripsema J, Ingkaninan K, Okonogi S. 3'-R/S-hydroxyvoacamine, a potent acetylcholinesterase inhibitor from Tabernaemontana divaricata. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2013; 20:543-548. [PMID: 23375813 DOI: 10.1016/j.phymed.2012.12.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/17/2012] [Accepted: 12/25/2012] [Indexed: 06/01/2023]
Abstract
Guided by the acetylcholinesterase inhibiting activity, the bisindole alkaloid 3'-R/S-hydroxyvoacamine was isolated from a stem extract of Tabernaemontana divaricata, a plant used in Thailand in traditional rejuvenation remedies for improving the memory. The structure of the alkaloid was elucidated by extensive use of NMR spectroscopy and the complete assignment of the (1)H and (13)C NMR spectra is reported. The alkaloid acted as a non-competitive inhibitor against AChE with an IC50 value of 7.00±1.99 μM. An HPLC method was developed for the quantitative analysis of the AChE inhibitor. It suggested that there was 12.4% (w/w) of 3'-R/S-hydroxyvoacamine in the alkaloid enriched fraction of T. divaricata stem.
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Affiliation(s)
- Wantida Chaiyana
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
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Preliminary studies of acetylcholinesterase activity in the rat brain using N-phenylferrocenecarboxamide labelled by the technetium-99m. Nucl Med Biol 2013; 40:561-6. [PMID: 23465564 DOI: 10.1016/j.nucmedbio.2013.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 12/15/2012] [Accepted: 01/26/2013] [Indexed: 11/20/2022]
Abstract
There is currently great interest in developing radiolabeled substrates for acetylcholinesterase that would be useful in the in vivo imaging of patients with Alzheimer's disease. The reduction of acetylcholinesterase (AChE) activity in the brain has been measured in dementia disorders such as Alzheimer's disease and dementia with Lewy bodies using (11)C and (18)F-labeled acetylcholine analogues. Our aim was to develop a new 99mTc-labeled acetylcholine analogue: N-phenylferrocenecarboxamide labelled with technetium-99m (99mTc-TPCC) to study acetylcholinesterase activity. In vivo and in vitro studies demonstrated that the labelled compound was a substrate for acetylcholinesterase. The hydrolytic rate of this substrate was measured and the specificity was evaluated using the inhibitor BW 284 C51. In rat experiments, the 99mTc-TPCC showed desirable properties for studying the acetylcholinesterase in the rat brain: high hydrolytic rate and a moderate specificity of the substrate for acetylcholinesterase.
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Chaiyana W, Okonogi S. Inhibition of cholinesterase by essential oil from food plant. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2012; 19:836-839. [PMID: 22510493 DOI: 10.1016/j.phymed.2012.03.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 02/10/2012] [Accepted: 03/09/2012] [Indexed: 05/31/2023]
Abstract
Inhibition of cholinesterase has attracted much attention recently because of its potential for the treatment of Alzheimer's disease. In this work, the anticholinesterase activities of plant oils were investigated using Ellman's colorimetric method. The results indicate that essential oils obtained from Melissa officinalis leaf and Citrus aurantifolia leaf showed high acetylcholinesterase and butyrylcholinesterase co-inhibitory activities. C. aurantifolia leaf oil revealed in this study has an IC(50) value on acetylcholinesterase and butyrylcholinesterase of 139 ± 35 and 42 ± 5 μg/ml, respectively. GC/MS analysis revealed that the major constituents of C. aurantifolia leaf oil are monoterpenoids including limonene, l-camphor, citronellol, o-cymene and 1,8-cineole.
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Affiliation(s)
- Wantida Chaiyana
- Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
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Synthesis and preliminary evaluation of piperidinyl and pyrrolidinyl iodobenzoates as imaging agents for butyrylcholinesterase. Mol Imaging Biol 2012; 13:1250-61. [PMID: 20976626 DOI: 10.1007/s11307-010-0448-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE The purpose of this study is to synthesize and evaluate specific agents for molecular imaging of butyrylcholinesterase (BuChE), known to be associated with neuritic plaques and neurofibrillary tangles in Alzheimer's disease (AD). In this study, these agents were tested in a normal rat model. The distribution of radiolabel was compared with known BuChE histochemical distribution in the rat brain. PROCEDURES Iodobenzoate esters were synthesized and tested, through spectrophotometric analysis, as specific substrates for BuChE. These compounds were converted to the corresponding (123)I esters from tributyltin intermediates and purified for studies in the rat model. Whole body dynamic scintigraphic images were obtained for biodistribution studies. Autoradiograms of brain sections were obtained and compared to histochemical distribution of the enzyme in this model system. RESULTS The three iodobenzoate esters studied were specific substrates for BuChE. Whole body biodistribution studies with (123)I-labeled compounds showed rapid disappearance from the body while radioactivity was retained in the head region. Brain section autoradiography of animals injected with these labeled compounds indicated that most areas known to contain BuChE corresponded to areas of radioactivity accumulation. CONCLUSION BuChE-specific radiolabeled iodobenzoates enter the brain and, in general, label areas known to exhibit BuChE activity in histochemical studies. Such molecules may represent a new direction for the development of agents for the molecular imaging of BuChE in the living brain, especially in regions where BuChE-containing neuropathological structures appear in AD.
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Macdonald IR, Jollymore CT, Reid GA, Pottie IR, Martin E, Darvesh S. Thioesters for the in vitro evaluation of agents to image brain cholinesterases. J Enzyme Inhib Med Chem 2012; 28:447-55. [DOI: 10.3109/14756366.2011.647008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ian R. Macdonald
- Department of Anatomy & Neurobiology and the Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Courtney T. Jollymore
- Department of Chemistry and Physics, Mount Saint Vincent University,
Halifax, Nova Scotia, Canada, B3M 2J6
| | - G. Andrew Reid
- Department of Anatomy & Neurobiology and the Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Ian R. Pottie
- Department of Chemistry and Physics, Mount Saint Vincent University,
Halifax, Nova Scotia, Canada, B3M 2J6
- Department of Chemistry, Saint Mary’s University,
Halifax, Nova Scotia, B3H 3C3
| | - Earl Martin
- Department of Chemistry and Physics, Mount Saint Vincent University,
Halifax, Nova Scotia, Canada, B3M 2J6
| | - Sultan Darvesh
- Department of Anatomy & Neurobiology and the Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
- Department of Chemistry and Physics, Mount Saint Vincent University,
Halifax, Nova Scotia, Canada, B3M 2J6
- Department of Medicine (Neurology and Geriatric Medicine), Dalhousie University,
Halifax, Nova Scotia, Canada, B3H 4R2
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Chaiyana W, Saeio K, Hennink WE, Okonogi S. Corrigendum to “Characterization of potent anticholinesterase plant oil based microemulsion” [Int. J. Pharm. 401 (2010) 32–40]. Int J Pharm 2011. [DOI: 10.1016/j.ijpharm.2011.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Guo DS, Uzunova VD, Su X, Liu Y, Nau WM. Operational calixarene-based fluorescent sensing systems for choline and acetylcholine and their application to enzymatic reactions. Chem Sci 2011. [DOI: 10.1039/c1sc00231g] [Citation(s) in RCA: 196] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Kikuchi T, Okamura T, Fukushi K, Irie T. Piperidine-4-methanthiol ester derivatives for a selective acetylcholinesterase assay. Biol Pharm Bull 2010; 33:702-6. [PMID: 20410609 DOI: 10.1248/bpb.33.702] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activity of acetylcholinesterase (AChE) is measured to obtain pathological information about the cholinergic system in various disease states and to assess the effect of AChE inhibitors. Using Ellman's method that is commonly used in such examinations, butyrylcholinesterase inhibitors must be added to measure AChE-specific activity because of low selectivity of AChE toward traditional substrates; however, such inhibitors also inhibit AChE. Therefore, it is desirable to obtain an AChE selective substrate that can be used with the Ellman's method. Here, we synthesized novel AChE substrates, 1-methyl-4-acetylthiomethylpiperidine and 1,1-dimethyl-4-acetylthiomethylpiperidine, and evaluated the hydrolysis rate and AChE selectivity by comparison with the results obtained when traditional substrates were used. The hydrolysis rate of the novel compounds by human AChE was one order of magnitude lower than that of the traditional substrates, acetylthiocholine and acetyl-beta-methylthiocholine, whereas the hydrolysis rate using human butyrylcholinesterase was two orders of magnitude lower than that of the traditional substrates. This indicated that AChE showed selectivity towards the novel substrates which was one order of magnitude higher than that of the traditional substrates. The hydrolysis of the novel compounds in a rat cerebral cortical homogenate and a monkey whole blood was completely inhibited by 1 muM of the specific AChE inhibitor, 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one, indicating the high specificity of AChE towards the novel substrates in a crude tissue sample. From these results, we conclude that the novel compounds developed would be suitable AChE-selective substrates for Ellman's method.
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Affiliation(s)
- Tatsuya Kikuchi
- Molecular Probe Group, Molecular Imaging Center, National Institute of Radiological Sciences, Japan.
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Chaiyana W, Saeio K, Hennink WE, Okonogi S. Characterization of potent anticholinesterase plant oil based microemulsion. Int J Pharm 2010; 401:32-40. [PMID: 20837121 DOI: 10.1016/j.ijpharm.2010.09.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/28/2010] [Accepted: 09/05/2010] [Indexed: 12/16/2022]
Abstract
In the present study, essential oils of three edible Thai plants, Cymbopogon citratus (Gramineae), Citrus hystrix (Rutaceae) and Zingiber cassumunar (Zingiberaceae) were comparatively tested for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities using Ellman's colorimetric method. C. citratus oil exhibited the highest activity with IC(50) values of 0.34±0.07μl/ml and 2.14±0.18μl/ml against BChE and AChE activity, respectively. It was further investigated whether microemulsions of this oil could be obtained. The effects of type of surfactant and co-surfactant as well as pH and ionic strength on the phase behavior of the oil/water system were investigated. Brij 97, Triton X-114, Tween 20 and Tween 85 were employed as surfactant whereas ethanol and hexanol were used as cosurfactants. The size analysis, electrical conductivity measurements and cholinesterase inhibition assays were done in selected microemulsion. The results revealed that the type and concentration of surfactant and co-surfactant exhibited a distinct influence on the C. citratus oil microemulsions. Moreover, the inhibitory activities of the microemulsion formulation were remarkable.
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Affiliation(s)
- Wantida Chaiyana
- Department of Pharmaceutical Science, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand
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Use of a novel radiometric method to assess the inhibitory effect of donepezil on acetylcholinesterase activity in minimally diluted tissue samples. Br J Pharmacol 2010; 159:1732-42. [PMID: 20401964 DOI: 10.1111/j.1476-5381.2010.00674.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Cholinesterase inhibitors have been widely used for the treatment of patients with dementia. Monitoring of the cholinesterase activity in the blood is used as an indicator of the effect of the cholinesterase inhibitors in the brain. The selective measurement of cholinesterase with low tissue dilution is preferred for accurate monitoring; however, the methods have not been established. Here, we investigated the effect of tissue dilution on the action of cholinesterase inhibitors using a novel radiometric method with selective substrates, N-[(14)C]methylpiperidin-4-yl acetate ([(14)C]MP4A) and (R)-N- [(14)C]methylpiperidin-3-yl butyrate ([(14)C]MP3B_R), for AChE and butyrylcholinesterase (BChE) respectively. EXPERIMENTAL APPROACH We investigated the kinetics of hydrolysis of [(14)C]-MP4A and [(14)C]-MP3B_R by cholinesterases, and evaluated the selectivity of [(14)C]MP4A and [(14)C]MP3B_R for human AChE and BChE, respectively, compared with traditional substrates. Then, IC(50) values of cholinesterase inhibitors in minimally diluted and highly diluted tissues were measured with [(14)C]MP4A and [(14)C]MP3B_R. KEY RESULTS AChE and BChE activities were selectively measured as the first-order hydrolysis rates of [(14)C]-MP4A and [(14)C]MP3B_R respectively. The AChE selectivity of [(14)C]MP4A was an order of magnitude higher than traditional substrates used for the AChE assay. The IC(50) values of specific AChE and BChE inhibitors, donepezil and ethopropazine, in 1.2-fold diluted human whole blood were much higher than those in 120-fold diluted blood. In addition, the IC(50) values of donepezil in monkey brain were dramatically decreased as the tissue was diluted. CONCLUSIONS AND IMPLICATIONS This method would effectively monitor the activity of cholinesterase inhibitors used for therapeutics, pesticides and chemical warfare agents.
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Herholz K. Acetylcholine esterase activity in mild cognitive impairment and Alzheimer's disease. Eur J Nucl Med Mol Imaging 2008; 35 Suppl 1:S25-9. [PMID: 18196237 DOI: 10.1007/s00259-007-0699-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
PURPOSE Impairment of cholinergic neurotransmission is a well-established fact in Alzheimer's disease (AD), but there is controversy about its relevance at the early stages of the disease and in mild cognitive impairment (MCI). METHODS In vivo positron emission tomography imaging of cortical acetylcholine esterase (AChE) activity as a marker of cholinergic innervation that is expressed by cholinergic axons and cholinoceptive neurons has demonstrated a reduction of this enzyme activity in manifest AD. The technique is also useful to measure the inhibition of cerebral AChE induced by cholinesterase inhibitors for treatment of dementia symptoms. RESULTS A reduction of cortical AchE activity was found consistently in all studies of AD and in few cases of MCI who later concerted to AD. CONCLUSION The in vivo findings in MCI and very mild AD are still preliminary, and studies seem to suggest that cholinergic innervation and AChE as the main degrading enzyme are both reduced, which might result in partial compensation of their effect.
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Affiliation(s)
- Karl Herholz
- Wolfson Molecular Imaging Centre, Clinical Neuroscience, University of Manchester, 27 Palatine Road, Manchester, UK.
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Virta JR, Tolvanen T, Någren K, Brück A, Roivainen A, Rinne JO. 1-11C-Methyl-4-Piperidinyl-N-Butyrate Radiation Dosimetry in Humans by Dynamic Organ-Specific Evaluation. J Nucl Med 2008; 49:347-53. [DOI: 10.2967/jnumed.107.047233] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Herholz K, Weisenbach S, Kalbe E. Deficits of the cholinergic system in early AD. Neuropsychologia 2007; 46:1642-7. [PMID: 18201734 DOI: 10.1016/j.neuropsychologia.2007.11.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Revised: 11/07/2007] [Accepted: 11/28/2007] [Indexed: 10/22/2022]
Abstract
Impairment of cholinergic neurotransmission is a well-established fact in Alzheimer's disease (AD) but there is controversy about its relevance at the early stages of the disease. In the recent years new techniques for in vivo imaging of key components of the cholinergic system in humans have developed. They are beginning to be applied to the very early stages of AD. Preliminary results suggest that there is early impairment of presynaptic receptors and acetylcholine esterase, the main degrading enzyme for acetylcholine, in cerebral cortex. The relation of these findings to neuronal function and post-mortem findings is being discussed.
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Bohnen NI, Frey KA. Imaging of cholinergic and monoaminergic neurochemical changes in neurodegenerative disorders. Mol Imaging Biol 2007; 9:243-57. [PMID: 17318670 DOI: 10.1007/s11307-007-0083-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Positron emission tomography (PET) or single photon emission computer tomography (SPECT) imaging provides the means to study neurochemical processes in vivo. These methods have been applied to examine monoaminergic and cholinergic changes in neurodegenerative disorders. These investigations have provided important insights into disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). The most intensely studied monoaminergic transmitter is dopamine. The extent of presynaptic nigrostriatal dopaminergic denervation can be quantified in PD and may serve as a diagnostic biomarker. Dopaminergic receptor imaging may help to distinguish idiopathic PD from atypical parkinsonian disorders. Cholinergic denervation has been identified not only in AD but also in PD and more severely in parkinsonian dementia. PET or SPECT can also provide biomarkers to follow progression of disease or evaluate the effects of therapeutic interventions. Cholinergic receptor imaging is expected to play a major role in new drug development for dementing disorders.
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Affiliation(s)
- Nicolaas I Bohnen
- Departments of Radiology & Neurology, The University of Michigan Medical School, Ann Arbor, MI, USA
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Kuhl DE, Koeppe RA, Snyder SE, Minoshima S, Frey KA, Kilbourn MR. Imaging butyrylcholinesterase activity in Alzheimer's disease. Ann Neurol 2006; 60:746. [PMID: 17192935 DOI: 10.1002/ana.21023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kuhl DE, Koeppe RA, Snyder SE, Minoshima S, Frey KA, Kilbourn MR. In vivo butyrylcholinesterase activity is not increased in Alzheimer's disease synapses. Ann Neurol 2006; 59:13-20. [PMID: 16278840 DOI: 10.1002/ana.20672] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE We tested the premise that cholinesterase inhibitor therapy should target butyrylcholinesterase (BuChE) in Alzheimer's disease (AD), not acetylcholinesterase (AChE) alone, because both enzymes hydrolyze acetylcholine, and BuChE is increased in AD cerebral cortex. METHODS To examine this issue in vivo, we quantified human cerebral cortical BuChE activity using tracer kinetic estimates (k(3)) of 1-[(11)C]methyl-4-piperidinyl n-butyrate ([(11)C]BMP) hydrolysis determined by positron emission tomography. Validation of the putative positron emission tomography method included regional distribution, positive correlation with age, and attenuation by the nonselective cholinesterase inhibitor physostigmine, but no attenuation by the AChE-selective inhibitor donepezil. Positron emission tomography scans in AD patients (n = 15) and control subjects (n = 12) measured both BuChE (using [(11)C]BMP) and AChE activity (using N-[(11)C] methylpiperidin-4-yl propionate, an established method). RESULTS As expected, AChE activity in AD cerebral cortex was decreased to 75 +/- 13% of normal (p = 0.00001). Contrary to prediction, accompanying BuChE activity also was decreased to 82 +/- 14% of normal (p = 0.001). INTERPRETATION Failure to observe increased [(11)C]BMP hydrolysis in vivo makes it less likely that incremental BuChE contributes importantly to acetylcholine hydrolysis in AD. The findings do not support the premise that inhibitor therapy should target BuChE so as to prevent increased levels of BuChE from hydrolyzing acetylcholine in AD cerebral cortex.
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Affiliation(s)
- David E Kuhl
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical Center, 1500 East Medical Center Drive, Ann Arbor, MI 48109, USA.
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Shao X, Koeppe RA, Butch ER, Kilbourn MR, Snyder SE. Evaluation of 18F-labeled acetylcholinesterase substrates as PET radiotracers. Bioorg Med Chem 2005; 13:869-75. [PMID: 15653352 DOI: 10.1016/j.bmc.2004.10.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2004] [Revised: 10/14/2004] [Accepted: 10/14/2004] [Indexed: 11/24/2022]
Abstract
Four 18F-labeled acetylcholinesterase (AChE) substrates, (S)-N-[18F]fluoroethyl-2-piperidinemethyl acetate (1), (R)-N-[18F]fluoroethyl-3-pyrrolidinyl acetate (2), N-[18F]fluoroethyl-4-piperidinyl acetate (3), and (R)-N-[18F]fluoroethyl-3-piperidinyl acetate (4), were evaluated for in vivo blood and brain metabolism in mice, brain pharmacokinetics in rats monkeys (M. nemistrina) using PET imaging. All 18F-labeled compounds were compared to N-[11C]methyl-4-piperidinyl propionate (PMP). Compound 1 was completely metabolized within 1 min in mouse blood and brain. This compound had relatively fast regional brain pharmacokinetics and poor discrimination between brain regions with different AChE concentration. Compound 4 showed relatively slower blood metabolism and slower pharmacokinetics than compound 1 but again poor discrimination between brain regions. Both compounds 1 and 4 showed different kinetic profiles than PMP in PET studies. Compound 3 had the slowest blood metabolism and slower pharmacokinetics than PMP. Compound 2 showed highly encouraging characteristics with an in vivo metabolism rate, primate brain uptake, and regional brain pharmacokinetics similar to [11C]PMP. The apparent hydrolysis rate constant k3 in primate cortex was very close to that of [11C]PMP. This compound has potential to be a good PET radiotracer for measuring brain AChE activity. The longer lifetime of 18F would permit longer imaging times and allows preparation of radiotracer batches for multiple patients and delivery of the tracer to other facilities, making the technique more widely available to clinical investigators.
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Affiliation(s)
- Xia Shao
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
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Kikuchi T, Zhang MR, Ikota N, Fukushi K, Okamura T, Suzuki K, Arano Y, Irie T. N-[18F]fluoroethylpiperidin-4-ylmethyl butyrate: a novel radiotracer for quantifying brain butyrylcholinesterase activity by positron emission tomography. Bioorg Med Chem Lett 2004; 14:1927-30. [PMID: 15050629 DOI: 10.1016/j.bmcl.2004.01.080] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 01/26/2004] [Accepted: 01/27/2004] [Indexed: 11/19/2022]
Abstract
In Alzheimer's disease, cerebral cortical butyrylcholinesterase (BChE) activity is reported to be elevated. Our aim was to develop a novel (18)F-labeled tracer for quantifying cerebral BChE activity by positron emission tomography. With in vitro screening of N-[(14)C]ethylpiperidin-3- and 4-ylmethyl esters, N-[(14)C]ethylpiperidin-4-ylmethyl butyrate was selected as a lead for (18)F-labeling, affording N-[(18)F]fluoroethylpiperidin-4-ylmethyl butyrate. The (18)F-labeled butyrate showed the required properties for in vivo BChE measurement, that is, the lipophilic nature of the authentic ester, high specificity to BChE, a moderate hydrolysis rate, and the hydrophilic nature of the metabolite.
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Affiliation(s)
- Tatsuya Kikuchi
- Department of Medical Imaging, National Institute of Radiological Sciences, Chiba 263-8555, Japan
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Nordberg A. Functional studies of cholinergic activity in normal and Alzheimer disease states by imaging technique. PROGRESS IN BRAIN RESEARCH 2003; 145:301-10. [PMID: 14650924 DOI: 10.1016/s0079-6123(03)45021-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Agneta Nordberg
- Karolinska Institute, Neurotec Department, Division of Molecular Neuropharmacology, Huddinge University Hospital, S-141 86 Stockholm, Sweden.
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Shao X, Butch ER, Kilbourn MR, Snyder SE. N-[(18)F]Fluoroethylpiperidinyl, N-[(18)F]fluoroethylpiperidinemethyl and N-[(18)F]fluoroethylpyrrolidinyl esters as radiotracers for acetylcholinesterase. Nucl Med Biol 2003; 30:491-500. [PMID: 12831986 DOI: 10.1016/s0969-8051(03)00031-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A series of N-fluoroethylpiperidinyl (1), N-fluoroethylpiperidinemethyl (2) and N-fluoroethylpyrrolidinyl (3) esters were synthesized and examined as new (18)F-labeled radiotracers for measuring brain cholinesterase activity. The fluoroethyl group, instead of methyl group, results in slower in vitro enzymatic cleavage rates and higher selectivity for AChE. Based on metabolism in mouse blood and PET time-activity curves in rats, two radiotracers were identified as potential candidates for further in vivo evaluation in higher species.
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Affiliation(s)
- Xia Shao
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
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Shao X, Lisi JM, Butch ER, Kilbourn MR, Snyder SE. N-methylpiperidinemethyl, N-methylpyrrolidyl and N-methylpyrrolidinemethyl esters as PET radiotracers for acetylcholinesterase activity. Nucl Med Biol 2003; 30:293-302. [PMID: 12745021 DOI: 10.1016/s0969-8051(02)00438-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The N-[(11)C]methylpiperidinyl esters are used as radiopharmaceuticals for measuring brain cholinesterase activity. We have synthesized a series of N-methylpiperidinemethyl (1), N-methylpyrrolidinyl (2) and N-methylpyrrolidinemethyl (3) esters and examined the effects of sterric constraint and stereochemistry on cholinesterase-mediated cleavage. Acetylcholinesterase exhibited a preference for primary esters 1 and for the R-isomers of both 1 and 2. Biological data for (S)-N-[(11)C]methyl-2-piperidinemethyl acetate (1a) were similar to [(11)C]AMP. These data better define the structure-activity relationships for cholinesterase radiotracers and provide lead compounds for (18)F- labeling.
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Affiliation(s)
- Xia Shao
- Division of Nuclear Medicine, Department of Radiology, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
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Musachio JL, Flesher JE, Scheffel UA, Rauseo P, Hilton J, Mathews WB, Ravert HT, Dannals RF, Frost JJ. Radiosynthesis and mouse brain distribution studies of [11C] CP-126,998: a PET ligand for in vivo study of acetylcholinesterase. Nucl Med Biol 2002; 29:547-52. [PMID: 12088724 DOI: 10.1016/s0969-8051(02)00299-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The selective, reversible acetylcholinesterase inhibitor 5,7-Dihydro-7-methyl-3- [2-[1-(phenylmethyl]-4-piperidinyl]ethyl]-6H-pyrrolo[3,2-f]-1,2-benzisoxazol3-6-one (CP-126,998) was labeled with C-11 iodomethane via base-promoted alkylation of the lactam nitrogen. [11C] CP-126,998 was synthesized in good radiochemical yield (13-29% non-decay corrected) and high specific radioactivity (177-418 GBq/micromol). In vivo mouse biodistribution studies reveal [11C] CP-126,998 to localize preferentially in striatal tissue, a region known to be rich in acetylcholinesterase. Competitive blocking studies using a variety of acetylcholinesterase inhibitors (diisopropylfluorophosphate, tacrine, CP-118,954) verified the specificity of the PET radiotracer for brain acetylcholinesterase.
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Affiliation(s)
- John L Musachio
- Johns Hopkins University School of Medicine, Department of Radiology, Division of Nuclear Medicine, Baltimore, MD 21287, USA.
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Snyder SE, Shao X, Lisi JM, Butch ER, Skaddan MB, Kilboum MR. Effect of stereochemistry on ester hydrolysis by cholinesterases: Implications for radiotracer design. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.2580440138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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