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Zirbesegger K, Reyes L, Paolino A, Dapueto R, Arredondo F, Gambini JP, Savio E, Porcal W. Molecular Imaging of Monoamine Oxidase A Expression in Highly Aggressive Prostate Cancer: Synthesis and Preclinical Evaluation of Positron Emission Tomography Tracers. ACS Pharmacol Transl Sci 2023; 6:1734-1744. [PMID: 37982127 PMCID: PMC10653014 DOI: 10.1021/acsptsci.3c00175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 11/21/2023]
Abstract
The role of monoamine oxidase A (MAO-A) in the aggressiveness of prostate cancer (PCa) has been established in recent years. The molecular imaging of MAO-A expression could offer a noninvasive tool for the visualization and quantification of highly aggressive PCa. This study reports the synthesis and preclinical evaluation of 11C- and 18F-labeled MAO-A inhibitors as positron emission tomography (PET) tracers for proof-of-concept studies in animal models of PCa. Good manufacturing practice production and quality control of these radiotracers using an automated platform was achieved. PET imaging was performed in an LNCaP tumor model with high MAO-A expression. The tumor-to-muscle (T/M) uptake ratio of [11C]harmine (4.5 ± 0.5) was significantly higher than that for 2-[18F]fluoroethyl-harmol (2.3 ± 0.7) and [11C]clorgyline (2.0 ± 0.1). A comparable ex vivo biodistribution pattern in all radiotracers was observed. Furthermore, the tumor uptake of [11C]harmine showed a dramatic reduction (T/M = 1) in a PC3 tumor model with limited MAO-A expression, and radioactivity uptake in LNCaP tumors was blocked in the presence of nonradioactive harmine. Our findings suggest that [11C]harmine may serve as an attractive PET probe for the visualization of MAO-A expression in highly aggressive PCa. These radiotracers have the potential for clinical translation and may aid in the development of personalized therapeutic strategies for PCa patients.
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Affiliation(s)
- Kevin Zirbesegger
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
- Programa de Posgrado, Facultad de Química, Universidad de la República, Av. General Flores 2124, 11800 Montevideo, Uruguay
| | - Laura Reyes
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Andrea Paolino
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Rosina Dapueto
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Florencia Arredondo
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Juan P Gambini
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Eduardo Savio
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Williams Porcal
- Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Av. General Flores 2124, 11800 Montevideo, Uruguay
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2
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Handschuh PA, Murgaš M, Vraka C, Nics L, Hartmann AM, Winkler-Pjrek E, Baldinger-Melich P, Wadsak W, Winkler D, Hacker M, Rujescu D, Domschke K, Lanzenberger R, Spies M. Effect of MAOA DNA Methylation on Human in Vivo Protein Expression Measured by [11C]harmine Positron Emission Tomography. Int J Neuropsychopharmacol 2023; 26:116-124. [PMID: 36573644 PMCID: PMC9926052 DOI: 10.1093/ijnp/pyac085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 12/26/2022] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Epigenetic modifications like DNA methylation are understood as an intermediary between environmental factors and neurobiology. Cerebral monoamine oxidase A (MAO-A) levels are altered in depression, as are DNA methylation levels within the MAOA gene, particularly in the promoter/exon I/intron I region. An effect of MAOA methylation on peripheral protein expression was shown, but the extent to which methylation affects brain MAO-A levels is not fully understood. METHODS Here, the influence of MAOA promoter/exon I/intron I region DNA methylation on global MAO-A distribution volume (VT), an index of MAO-A density, was assessed via [11C]harmine positron emission tomography in 22 patients (14 females) suffering from seasonal affective disorder and 30 healthy controls (17 females). RESULTS No significant influence of MAOA DNA methylation on global MAO-A VT was found, despite correction for health status, sex, season, and MAOA variable number of tandem repeat genotype. However, season affected average methylation in women, with higher levels in spring and summer (Puncorr = .03). We thus did not find evidence for an effect of MAOA DNA methylation on brain MAO-A VT. CONCLUSIONS In contrast to a previous study demonstrating an effect of methylation of a MAOA promoter region located further 5' on brain MAO-A, MAOA methylation of the region assessed here appears to affect brain protein levels to a limited extent at most. The observed effect of season on methylation levels is in accordance with extensive evidence for seasonal effects within the serotonergic system. CLINICALTRIALS.GOV IDENTIFIER NCT02582398 (https://clinicaltrials.gov/ct2/show/NCT02582398).
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Affiliation(s)
- Patricia A Handschuh
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Matej Murgaš
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Chrysoula Vraka
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
| | - Lukas Nics
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
| | - Annette M Hartmann
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Edda Winkler-Pjrek
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Pia Baldinger-Melich
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Wolfgang Wadsak
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
- Center for Biomarker Research in Medicine (CBmed), Graz, Austria
| | - Dietmar Winkler
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Marcus Hacker
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Austria
| | - Dan Rujescu
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Katharina Domschke
- Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Centre for Basics in Neuromodulation, Faculty of Medicine, University of Freiburg, Germany
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
| | - Marie Spies
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria
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3
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Shegani A, Kealey S, Luzi F, Basagni F, Machado JDM, Ekici SD, Ferocino A, Gee AD, Bongarzone S. Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds. Chem Rev 2022; 123:105-229. [PMID: 36399832 PMCID: PMC9837829 DOI: 10.1021/acs.chemrev.2c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.
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Affiliation(s)
- Antonio Shegani
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Steven Kealey
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Federico Luzi
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Filippo Basagni
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−University of Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | - Joana do Mar Machado
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Sevban Doğan Ekici
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom
| | - Alessandra Ferocino
- Institute
of Organic Synthesis and Photoreactivity, Italian National Research Council, via Piero Gobetti 101, 40129 Bologna, Italy
| | - Antony D. Gee
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,A.G.: email,
| | - Salvatore Bongarzone
- School
of Biomedical Engineering & Imaging Sciences, King’s College London, King’s Health Partners, St Thomas’ Hospital, London SE1 7EH, United Kingdom,S.B.:
email,
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Thentu JB, Bhyrapuneni G, Padala NP, Chunduru P, Pantangi HR, Nirogi R. Evaluation of monoamine oxidase A and B type enzyme occupancy using non-radiolabelled tracers in rat brain. Neurochem Int 2021; 145:105006. [PMID: 33636211 DOI: 10.1016/j.neuint.2021.105006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Monoamine oxidase (MAO) enzymes, type A and B metabolise the amine neurotransmitters of the body. Selective inhibition of either enzyme is an approach for treating neurodegenerative and stress-induced disorders, and inhibition of an enzyme is proportional to the binding of the MAO inhibitor. Conventionally, the binding of test compounds to enzymes is assessed by radiolabelled ligands in ex vivo and in vivo occupancy assays. Regulatory restrictions and turnaround time are the limitations of the methods that use radiolabelled ligands. But the use of non-radiolabelled tracers and sensitive mass spectrometry (LC-MS/MS) based assays accelerated the determination of target occupancy in pre-clinical species. A report on use of non-radiolabelled ligand in in vivo MAO occupancy assay is not available. The objectives of the present study were to optimise non-radiolabelled harmine and deprenyl as selective tracers in MAO-A and MAO-B occupancy assays and evaluate MAO occupancy of test compounds in rat brain. Tracer optimisation resulted in a detectable, stable, and low ratio (<3.0) of tracer concentrations between any two brain tissues. In occupancy assay, tracer was intravenously administered (10 μg/kg, harmine or 60 μg/kg, L-deprenyl) after the treatment with test compound (clorgyline or tranylcypromine or pargyline or phenelzine or thioperamide). Specific brain tissues were isolated at a defined interval and tracer concentrations were quantified using LC-MS/MS method. Pre-treatment with MAO inhibitors resulted in a decrease (maximum, 80-85%) in harmine or an increase (maximum, 85-300%) in L-deprenyl concentrations. But we considered the change in tracer concentration, relative to the vehicle and positive control groups to calculate MAO occupancy. The observed selectivity and ratio of occupancies (ED50) of test compound towards MAO-A and MAO-B are comparable with the results from in vitro radiolabelled ligand-based inhibition assay. The results demonstrated the application of these non-radiolabelled tracers as suitable pre-clinical tools to determine MAO occupancy.
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Affiliation(s)
- Jagadeesh Babu Thentu
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Gopinadh Bhyrapuneni
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Nagasurya Prakash Padala
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Prathyusha Chunduru
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Hanumanth Rao Pantangi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Ramakrishna Nirogi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
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L'Estrade ET, Erlandsson M, Edgar FG, Ohlsson T, Knudsen GM, Herth MM. Towards selective CNS PET imaging of the 5-HT 7 receptor system: Past, present and future. Neuropharmacology 2019; 172:107830. [PMID: 31669129 DOI: 10.1016/j.neuropharm.2019.107830] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 09/24/2019] [Accepted: 10/23/2019] [Indexed: 11/25/2022]
Abstract
Since its discovery in 1993, the serotonin receptor subtype 7 (5-HT7) has attracted significant attention as a potential drug target; due to its elucidated roles in conditions such as insomnia, schizophrenia, and more. Therefore, it is unsurprising that there has been relatively early efforts undertaken to develop a positron emission tomography (PET) imaging agent for said receptor system. PET can be clinically used to probe receptor systems in vivo, permitting information such as a drug's occupancy against this system to be investigated. This review focuses on the efforts towards the development of a 5-HT7R selective PET CNS tracer over the last 20 years, critically reflecting on applied strategies and commonly employed chemical frameworks and suggests future considerations that are needed to successfully develop a PET tracer for this clinically relevant target. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.
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Affiliation(s)
- Elina T L'Estrade
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark; Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Maria Erlandsson
- Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Fraser G Edgar
- Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark
| | - Tomas Ohlsson
- Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Gitte M Knudsen
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Matthias M Herth
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine and PET, University Hospital Copenhagen, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.
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6
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Zanderigo F, D’Agostino AE, Joshi N, Schain M, Kumar D, Parsey RV, DeLorenzo C, Mann JJ. [11C]Harmine Binding to Brain Monoamine Oxidase A: Test-Retest Properties and Noninvasive Quantification. Mol Imaging Biol 2018; 20:667-681. [DOI: 10.1007/s11307-018-1165-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Chiuccariello L, Cooke RG, Miler L, Levitan RD, Baker GB, Kish SJ, Kolla NJ, Rusjan PM, Houle S, Wilson AA, Meyer JH. Monoamine Oxidase-A Occupancy by Moclobemide and Phenelzine: Implications for the Development of Monoamine Oxidase Inhibitors. Int J Neuropsychopharmacol 2015; 19:pyv078. [PMID: 26316187 PMCID: PMC4772270 DOI: 10.1093/ijnp/pyv078] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 07/05/2015] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Monoamine oxidase inhibitors (MAOIs) are being developed for major depressive disorder, Alzheimer's, and Parkinson's Disease. Newer MAOIs have minimal sensitivity to tyramine, but a key limitation for optimizing their development is that standards for in vivo monoamine oxidase-A (MAO-A) occupancy in humans are not well established. The objectives were to determine the dose-occupancy relationship of moclobemide and the occupancy of phenelzine at typical clinical dosing. METHODS Major depressive episode (MDE) subjects underwent [(11)C]harmine positron emission tomography scanning prior to and following 6 weeks of treatment with moclobemide or phenelzine. RESULTS Mean brain MAO-A occupancies were 74.23±8.32% for moclobemide at 300-600 mg daily (n = 11), 83.75±5.52% for moclobemide at 900-1200 mg daily (n = 9), and 86.82±6.89% for phenelzine at 45-60 mg daily (n = 4). The regional dose-occupancy relationship of moclobemide fit a hyperbolic function [F(x) = a(x/[b + x]); F(1,18) = 5.57 to 13.32, p = 0.002 to 0.03, mean 'a': 88.62±2.38%, mean 'b': 69.88±4.36 mg]. Multivariate analyses of variance showed significantly greater occupancy of phenelzine (45-60mg) and higher-dose moclobemide (900-1200 mg) compared to lower-dose moclobemide [300-600 mg; F(7,16) = 3.94, p = 0.01]. CONCLUSIONS These findings suggest that for first-line MDE treatment, daily moclobemide doses of 300-600mg correspond to a MAO-A occupancy of 74%, whereas for treatment-resistant MDE, either phenelzine or higher doses of moclobemide correspond to a MAO-A occupancy of at least 84%. Therefore, novel MAO inhibitor development should aim for similar thresholds. The findings provide a rationale in treatment algorithm design to raise moclobemide doses to inhibit more MAO-A sites, but suggest switching from high-dose moclobemide to phenelzine is best justified by binding to additional targets.
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Affiliation(s)
- Lina Chiuccariello
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Robert G Cooke
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Laura Miler
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Robert D Levitan
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Glen B Baker
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Stephen J Kish
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Nathan J Kolla
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Pablo M Rusjan
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Sylvain Houle
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Alan A Wilson
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker)
| | - Jeffrey H Meyer
- CAMH Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health and Departments of Psychiatry, Pharmacology and Toxicology, and Institute of Medical Sciences, University of Toronto, Canada (Drs Chiuccariello, Cooke, Levitan, Kish, Kolla, Rusjan, Houle, Wilson, and Meyer, and Ms Miler); Department of Psychiatry (NRU) and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada (Dr Baker).
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Selective binding to monoamine oxidase A: In vitro and in vivo evaluation of 18F-labeled β-carboline derivatives. Bioorg Med Chem 2015; 23:612-23. [DOI: 10.1016/j.bmc.2014.11.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 11/04/2014] [Accepted: 11/27/2014] [Indexed: 01/09/2023]
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9
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Philippe C, Zeilinger M, Mitterhauser M, Dumanic M, Lanzenberger R, Hacker M, Wadsak W. Parameter evaluation and fully-automated radiosynthesis of [(11)C]harmine for imaging of MAO-A for clinical trials. Appl Radiat Isot 2015; 97:182-187. [PMID: 25594603 PMCID: PMC4337850 DOI: 10.1016/j.apradiso.2015.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 12/04/2014] [Accepted: 01/04/2015] [Indexed: 11/18/2022]
Abstract
The aim of the present study was the evaluation and automation of the radiosynthesis of [11C]harmine for clinical trials. The following parameters have been investigated: amount of base, precursor concentration, solvent, reaction temperature and time. The optimum reaction conditions were determined to be 2–3 mg/mL precursor activated with 1 eq. 5 M NaOH in DMSO, 80 °C reaction temperature and 2 min reaction time. Under these conditions 6.1±1 GBq (51.0±11% based on [11C]CH3I, corrected for decay) of [11C]harmine (n=72) were obtained. The specific activity was 101.32±28.2 GBq/µmol (at EOS). All quality control parameters were in accordance with the standards for parenteral human application. Due to its reliability and high yields, this fully-automated synthesis method can be used as routine set-up. Preparation of [11C]harmine on a commercially available synthesizer for the routine application. High reliability: only 4 out of 72 failed syntheses; 5% due to technical problems. High yields: 6.1±1 GBq overall yield (EOS). High specific activities: 101.32±28.2 GBq/µmol.
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Affiliation(s)
- C Philippe
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | - M Zeilinger
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | - M Mitterhauser
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | - M Dumanic
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | - R Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, 1090 Vienna, Austria
| | - M Hacker
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
| | - W Wadsak
- Department of Biomedical Imaging and Image-guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
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Wilson AA, Garcia A, Parkes J, Houle S, Tong J, Vasdev N. [11C]CURB: Evaluation of a novel radiotracer for imaging fatty acid amide hydrolase by positron emission tomography. Nucl Med Biol 2011; 38:247-53. [PMID: 21315280 DOI: 10.1016/j.nucmedbio.2010.08.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 08/05/2010] [Accepted: 08/08/2010] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Fatty acid amide hydrolase (FAAH) is the enzyme responsible for metabolising the endogenous cannabinoid, anandamide, and thus represents an important target for molecular imaging. To date, no radiotracer has been shown to be useful for imaging of FAAH using either positron emission tomography (PET) or single photon emission computed tomography (SPECT). We here determine the suitability of a novel carbon-11-labeled inhibitor of FAAH via ex vivo biodistribution studies in rat brain in conjunction with pharmacological challenges. METHODS A potent irreversible inhibitor of FAAH, URB694, radiolabeled with carbon-11 in the carbonyl position ([(11)C]CURB), was administered to male rats via tail-vein injection. Rats were sacrificed at various time points postinjection, and tissue samples were dissected, counted and weighed. Specific binding to FAAH was investigated by pretreatment of animals with URB694 or URB597. For metabolism and mechanism of binding studies, whole brains were excised post-radiotracer injection, homogenised and extracted exhaustively with 80% aq. acetonitrile to determine the time course and fraction of radioactivity that was irreversibly bound to brain parenchyma. RESULTS Upon intravenous injection into rats, [(11)C]CURB showed high brain uptake [standard uptake value (SUV) of 1.6-2.4 at 5 min] with little washout over time, which is characteristic of irreversible binding. Highest uptake of radioactivity was seen in the cortex, intermediate in the cerebellum and lowest in the hypothalamus, reflecting the reported distribution of FAAH. Brain uptake of radioactivity was decreased in a dose-dependent manner by pretreatment with increasing amounts of URB694, demonstrating that binding was saturable. Pretreatment with the well-characterised FAAH inhibitor, URB597, reduced binding in all brain regions by 70-80%. Homogenised brain extraction experiments demonstrated unequivocally that [(11)C]CURB was irreversibly bound to FAAH. CONCLUSIONS The title radiotracer demonstrates favourable properties such as good brain uptake, regional heterogeneity and specificity of binding based on ex vivo biodistribution studies in conscious rat brain. [(11)C]CURB represents a highly promising radiotracer for the imaging of FAAH using PET.
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Affiliation(s)
- Alan A Wilson
- PET Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
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11
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In vivo quantification of monoamine oxidase A in baboon brain: a PET study using [(11)C]befloxatone and the multi-injection approach. J Cereb Blood Flow Metab 2010; 30:792-800. [PMID: 19920845 PMCID: PMC2949159 DOI: 10.1038/jcbfm.2009.242] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
[(11)C]befloxatone is a high-affinity, reversible, and selective radioligand for the in vivo visualization of the monoamine oxidase A (MAO-A) binding sites using positron emission tomography (PET). The multi-injection approach was used to study in baboons the interactions between the MAO-A binding sites and [(11)C]befloxatone. The model included four compartments and seven parameters. The arterial plasma concentration, corrected for metabolites, was used as input function. The experimental protocol-three injections of labeled and/or unlabeled befloxatone-allowed the evaluation of all the model parameters from a single PET experiment. In particular, the brain regional concentrations of the MAO-A binding sites (B'(max)) and the apparent in vivo befloxatone affinity (K(d)) were estimated in vivo for the first time. A high binding site density was found in almost all the brain structures (170+/-39 and 194+/-26 pmol/mL in the frontal cortex and striata, respectively, n=5). The cerebellum presented the lowest binding site density (66+/-13 pmol/mL). Apparent affinity was found to be similar in all structures (K(d)V(R)=6.4+/-1.5 nmol/L). This study is the first PET-based estimation of the B(max) of an enzyme.
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Bramoullé Y, Puech F, Saba W, Valette H, Bottlaender M, George P, Dollé F. Radiosynthesis of (S)-5-methoxymethyl-3-[6-(4,4,4-trifluorobutoxy)benzo[d]isoxazol-3-yl] oxazolidin-2-[11C]one ([11C]SL25.1188), a novel radioligand for imaging monoamine oxidase-B with PET. J Labelled Comp Radiopharm 2008. [DOI: 10.1002/jlcr.1492] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Blom E, Karimi F, Eriksson O, Hall H, Långström B. Synthesis andin vitro evaluation of18F-β-carboline alkaloids as PET ligands. J Labelled Comp Radiopharm 2008. [DOI: 10.1002/jlcr.1519] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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14
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Antoni G, Långström B. Radiopharmaceuticals: molecular imaging using positron emission tomography. Handb Exp Pharmacol 2008:177-201. [PMID: 18626804 DOI: 10.1007/978-3-540-72718-7_9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We describe the use of molecules labeled with short-lived emitting radionuclides for molecular imaging in combination with the positron emission tomography technique. How to use molecular probes to visualize and quantitatively determine rates of specific biochemical events such as synaptic transmission, enzymatic processes and binding to specific receptor proteins is highlighted. The sensitivity of the PET technique and the ability to measure and validate relationships between molecular events and biological functions is a key factor for the successful application of PET in biomedical research. In specific applications, the opportunity of using molecules labeled in specific positions may be critical. Molecular imaging using PET is also gaining increasing interest as a tool in drug development, especially when applied to early proof of concept studies in man. In this chapter, the concept of molecular imaging is exemplified and the use of position-specific labeling of tracer molecules as a tool to gain understanding of complex biological processes will be discussed.
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Affiliation(s)
- Gunnar Antoni
- GE Healthcare Uppsala Imanet AB, P.O. Box 967, 751 09, Uppsala, Sweden.
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15
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Zipursky RB, Meyer JH, Verhoeff NP. PET and SPECT imaging in psychiatric disorders. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2007; 52:146-57. [PMID: 17479522 DOI: 10.1177/070674370705200303] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVES To review recent findings from positron emission tomography (PET) and single photon emission computed tomography (SPECT) studies that investigate the pathophysiology and treatment of schizophrenia, depression, and dementia. METHODS We carried out a review of the literature. RESULTS PET and SPECT studies have provided evidence of dopamine system dysregulation in patients with schizophrenia and variable loss of monoamines in patients with depression. Antipsychotic response has been demonstrated to be associated with blockade of dopamine D2 receptors, and antidepressant response has now been linked to blockade of serotonin transporter receptors. PET and SPECT have been extensively evaluated as diagnostic procedures for dementia. Substantial progress has been made in developing radioligands that bind to amyloid deposits in the brain, which should provide new opportunities for early diagnosis and treatment monitoring in Alzheimer's disease. CONCLUSION Advances in PET and SPECT imaging have provided new insights into the biology of major psychiatric disorders and their treatment. In the future, we can expect that these imaging techniques will become more central to the management of psychiatric disorders.
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Affiliation(s)
- Robert B Zipursky
- Department of Psychiatry and Behavioural Neurosciences, Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario.
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16
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Lundquist P, Blomquist G, Hartvig P, Hagberg GE, Torstenson R, Hammarlund-Udenaes M, Långström B. Validation studies on the 5-hydroxy-L-[beta-11C]-tryptophan/PET method for probing the decarboxylase step in serotonin synthesis. Synapse 2006; 59:521-31. [PMID: 16565973 DOI: 10.1002/syn.20268] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The two-tissue compartment model, including irreversible trapping in the second compartment (2TCM) is used to describe the kinetics of 5-Hydroxy-L-[beta-(11)C]-tryptophan ([(11)C]HTP), a radioligand used in positron emission tomography (PET) for probing the second enzymatic step in the biosynthesis of serotonin. In this study, we examined the capacity of the model to track pharmacological changes in this biological process. We also investigated the potential loss of [(11)C]HTP-derived radioactivity during a PET study, since loss should be negligible not to alter quantification. Six rhesus monkeys were investigated using bolus [(11)C]HTP/PET methodology before and after pharmacological intervention. The second enzymatic step in serotonin synthesis was inhibited using the aromatic L-amino acid decarboxylase inhibitor NSD1015 (10 mg/kg). The extent of [(11)C]-derived radioactivity loss from the brain was studied by inhibition of the enzyme responsible for formation of the tissue metabolite, monoamine oxidase A, using clorgyline (2 mg/kg). After NSD1015, the uptake of [(11)C]HTP-derived radioactivity was increased in all the investigated brain regions, while the parameter used to reflect decarboxylase activity, the net accumulation rate constant (K(acc)), was decreased by 37% in the striatum, compared with baseline. Pretreatment with clorgyline did not change the brain uptake of [(11)C]HTP-derived radioactivity or K(acc). This study demonstrates that the 2TCM for [(11)C]HTP/PET is able to detect changes occurring during alteration of the biological process (i.e., the conversion of HTP to serotonin). Elimination of the radiotracer metabolite [(11)C]HIAA from the brain may be considered negligible if the PET study is limited to 60 min.
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Affiliation(s)
- Pinelopi Lundquist
- Division of Pharmacokinetics and Drug Therapy, Department of Pharmaceutical Biosciences,Uppsala University, Box 591, SE-751 24 Uppsala, Sweden
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Ginovart N, Meyer JH, Boovariwala A, Hussey D, Rabiner EA, Houle S, Wilson AA. Positron emission tomography quantification of [11C]-harmine binding to monoamine oxidase-A in the human brain. J Cereb Blood Flow Metab 2006; 26:330-44. [PMID: 16079787 DOI: 10.1038/sj.jcbfm.9600197] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This article describes the kinetic modeling of [(11)C]-harmine binding to monoamine oxidase A (MAO-A) binding sites in the human brain using positron emission tomography (PET). Positron emission tomography studies were performed in healthy volunteers at placebo conditions and after treatment with clinical doses of moclobemide. In either condition, a two-tissue compartment model (2CM) provided better fits to the data than a one-tissue model. Estimates of k(3)/k(4) values from an unconstrained 2CM were highly variable. In contrast, estimates of the specifically bound radioligand distribution volume (DV(B)) from an unconstrained 2CM were exceptionally stable, correlated well with the known distribution of MAO-A in the brain (cerebellum <frontal cortex approximately putamen <temporal cortex approximately cingulate <thalamus) and thus provided reliable indices of MAO-A density. Total distribution volume (DV) values were also highly stable and not different from those estimated with the Logan approach. Fixing the DV of free and nonspecifically bound radiotracer (DV(F + NS)) or coupling DV(F + NS) between brain regions enabled more stable estimates of k(3)/k(4) as compared with an unconstrained 2CM. Moclobemide treatment leads to a 64% to 79% MAO-A blockade across brain regions, a result that supports the specificity of [(11)C]-harmine binding to MAO-A. The stability and reliability of DV(B) values obtained from an unconstrained 2CM, together with the computational simplicity associated with this method, support the use of DV(B) as an appropriate outcome measure for [(11)C]-harmine. These results indicate the suitability of using [(11)C]-harmine for quantitative evaluation of MAO-A densities using PET and should enable further studies of potential MAO-A dysregulation in several psychiatric and neurologic illnesses.
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Affiliation(s)
- Nathalie Ginovart
- PET Centre, Centre for Addiction and Mental Health, Toronto, Canada.
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18
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Bergström M, Långström B. Pharmacokinetic studies with PET. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2006; 62:279-317. [PMID: 16329260 DOI: 10.1007/3-7643-7426-8_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Mats Bergström
- Uppsala Imanet, GE Health Care, Box 967, SE-751 09 Uppsala, Sweden.
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19
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Jensen SB, Olsen AK, Pedersen K, Cumming P. Effect of monoamine oxidase inhibition on amphetamine-evoked changes in dopamine receptor availability in the living pig: A dual tracer PET study with [11C]harmine and [11C]raclopride. Synapse 2006; 59:427-34. [PMID: 16485265 DOI: 10.1002/syn.20258] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The activity of both isozymes of monoamine oxidase (MAO) is reduced by 50% in the brain of human smokers. We hypothesized that this is not an epiphenomenon, but should bring about potentiation of the action of psychostimulant drugs. To test this hypothesis, we carried out serial positron emission tomography (PET) studies in Göttingen miniature pigs to measure the binding of the MAO-A ligand [11C]harmine and to measure the changes in [11C]raclopride binding evoked by a low dose of amphetamine (0.7 mg/kg as free base, i.v.), first in a baseline condition, and, one month later, after acute treatment with pargyline (2 x 3 mg/kg as free base, i.m.). In the baseline, the distribution volume of [11C]harmine relative to the arterial input (V(d), ml g(-1)) ranged from 74 ml g(-1) in cerebellum to 139 ml g(-1) in the medial hypothalamus. Pargyline treatment reduced the magnitude of V(d) globally to 34-54 ml g(-1). Nearly complete displacement of [11C]harmine binding was detected in neocortex and striatum, but there was evidence for pargyline-resistant binding in the pituitary gland and diencephalon. In the baseline condition, the low dose of amphetamine evoked a 14% decline in the binding potential (BP) (pB) of [11C]raclopride in striatum (P = 0.026). After pargyline treatment, the amphetamine effect was of similar magnitude (-11%), although not statistically significant (P = 0.054). However, the second amphetamine challenge evoked a 24% reduction in [11C]raclopride pB relative to the original baseline condition (P = 0.018). Present results do not strongly support our hypothesis that MAO inhibition should potentiate the amphetamine-evoked dopamine release as measured in the [11C]raclopride competition paradigm.
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Affiliation(s)
- Svend Borup Jensen
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, Aarhus C, Denmark 8000
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20
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Gatley SJ, Volkow ND, Fowler JS, Ding YS, Logan J, Wang GJ, Gifford AN. Positron emission tomography and its use to image the occupancy of drug binding sites. Drug Dev Res 2003. [DOI: 10.1002/ddr.10219] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bottlaender M, Dolle F, Guenther I, Roumenov D, Fuseau C, Bramoulle Y, Curet O, Jegham J, Pinquier JL, George P, Valette H. Mapping the cerebral monoamine oxidase type A: positron emission tomography characterization of the reversible selective inhibitor [11C]befloxatone. J Pharmacol Exp Ther 2003; 305:467-73. [PMID: 12606609 DOI: 10.1124/jpet.102.046953] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Befloxatone is a competitive and reversible inhibitor of monoamine oxidase-A (MAOI-A). The aim of the study was to characterize the in vivo properties of [(11)C]befloxatone and to validate its use as a ligand for the study of MAO-A by positron emission tomography (PET). PET studies were performed in baboons after i.v. injection of [(11)C]befloxatone (551 +/- 70 MBq, i.e.14.9 +/- 1.9 mCi). [(11)C]Befloxatone enters rapidly in the brain with a maximum uptake at 30 min. Brain concentration of the tracer is high in thalamus, striatum, pons and cortical structures (1.5-1.8% of injected dose per 100 ml of tissue), and lower in cerebellum (1.07% injected dose/100 ml). Nonsaturable uptake, obtained after a pretreatment with a high dose of nonlabeled befloxatone (0.4 mg/kg), is very low and represents only 3% of the total uptake. Brain uptake of [(11)C]befloxatone is not altered by a pretreatment of a high dose with lazabemide (0.5 mg/kg i.v.), a selective MAOI-B but is completely blocked by a pretreatment with moclobemide (MAOI-A; 10 mg/kg). This confirms, in vivo, the selectivity of befloxatone for type A MAO. [(11)C]Befloxatone brain radioactivity was displaced by administration of unlabeled befloxatone (30 min after the tracer injection). The displacement of the tracer from its binding sites is dose-dependent, with an ID(50) of 0.02 mg/kg for all studied structures. These results indicate that [(11)C]befloxatone will be an excellent probe for the study of MAO-A in humans using PET.
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Affiliation(s)
- Michel Bottlaender
- Commissariat à l'Energie Atomique, Service Hospitalier Frédéric Joliot, Département de Recherche Médicale/Direction des Sciences du Vivant, Orsay, France.
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22
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Abstract
Over the past 30 years, advances in radiotracer chemistry and positron emission tomography instrumentation have merged to make positron emission tomography a powerful scientific tool in the biomedical sciences. However, despite the increasing reliance of the biomedical sciences on imaging and the new needs for functional information created by the sequencing of the human genome, the development of new radiotracers with the specificity and kinetic characteristics for quantitative analysis in vivo remains a slow process. In this article, we focus on advances in the development of the radiotracers involved in neurotransmission, amino acid transport, protein synthesis, and DNA synthesis. We conclude with a brief section on newer radiotracers that image other molecular targets and conclude with a summary of some of the scientific and infrastructure needs that would expedite the development and introduction of new radiotracers into biomedical research and the practice of medicine.
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Affiliation(s)
- Joanna S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Fowler JS, Ding YS, Logan J, MacGregor RR, Shea C, Garza V, Gimi R, Volkow ND, Wang GJ, Schlyer D, Ferrieri R, Gatley SJ, Alexoff D, Carter P, King P, Pappas N, Arnett CD. Species differences in [11C]clorgyline binding in brain. Nucl Med Biol 2001; 28:779-85. [PMID: 11578898 DOI: 10.1016/s0969-8051(01)00245-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
[11C]Clorgyline selectively binds to MAO A in the human brain. This contrasts with a recent report that [11C]clorgyline (in contrast to other labeled MAO A inhibitors) is not retained in the rhesus monkey brain [4]. To explore this difference, we compared [11C]clorgyline in the baboon brain before and after clorgyline pretreatment and we also synthesized deuterium substituted [11C]clorgyline (and its nor-precursor) for comparison. [11C]Clorgyline was not retained in the baboon brain nor was it influenced by clorgyline pretreatment or by deuterium substitution, contrasting to results in humans. This suggests a species difference in the susceptibility of MAO A to inhibition by clorgyline and represents an unusual example of where the behavior of a radiotracer in the baboon brain does not predict its behavior in the human brain.
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Affiliation(s)
- J S Fowler
- Brookhaven National Laboratory, Upton, New York 11973, USA.
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McConathy J, Kilts CD, Goodman MM. Radioligands for PET and SPECT Imaging of the central noradrenergic system. CNS Spectr 2001; 6:704-9. [PMID: 15520617 DOI: 10.1017/s1092852900001401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In the central nervous system, the neurotransmitter norepinephrine is involved in normal physiology, neuropsychiatric disorders, and the effects of numerous drugs. Although alterations of the central noradrenergic system are involved in the pathophysiology and pharmacotherapy of mood disorders, the basis and nature of these changes remain unresolved. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging agents will be valuable for further elucidating the roles of norepinephrine in health and disease. This review discusses PET and SPECT radioligands that have been developed for the enzymes, receptors, and transporters involved in noradrenergic neurotransmission. Currently, imaging agents that exhibit specific in vivo uptake in the brain have been described for monoamine oxidase A and beta-adrenergic receptors, but have not undergone detailed evaluation or experimental application. Based on the successful development and utilization of in vivo imaging agents for elements of the central dopaminergic and serotoninergic systems, PET and SPECT radioligands are expected to serve as new tools for studying the physiology, pathophysiology, and pharmacology of the central noradrenergic system.
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Affiliation(s)
- J McConathy
- Neuroscience Program, Emory University, Atlanta, GA, USA.
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