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Saednia S, Emami S, Moslehi M, Hosseinimehr SJ. Insights into the development of 99mTc-radioligands for serotonergic receptors imaging: Synthesis, labeling, In vitro, and In vivo studies. Eur J Med Chem 2024; 270:116349. [PMID: 38555856 DOI: 10.1016/j.ejmech.2024.116349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/02/2024]
Abstract
Serotonergic (5-hydroxytryptamine; 5-HT) receptors play critical roles in neurological and psychological disorders such as schizophrenia, anxiety, depression, and Alzheimer's diseases. Therefore, it is particularly important to develop novel radioligands or modify the existing ones to identify the serotonergic receptors involved in psychiatric disorders. Among the 16 subtypes of serotonergic systems, only technetium-99m based radiopharmaceuticals have been evaluated for serotonin-1A (5-HT1A), serotonin-2A (5-HT2A), 5-HT1A/7 heterodimers and serotonin receptor neurotransmitter (SERT). This review focuses on recent efforts in the design, synthesis and evaluation of 99mTc-radioligands used for single photon emission computerized tomography (SPECT) imaging of serotonergic (5-HT) receptors. Additionally, the discussion will cover aspects such as chemical structure, in vitro/vivo stability, affinity toward serotonin receptors, blood-brain barrier permeation (BBB), and biodistribution study.
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Affiliation(s)
- Shahnaz Saednia
- Farabi Hospital, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Saeed Emami
- Department of Medicinal Chemistry and Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Masoud Moslehi
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Seyed Jalal Hosseinimehr
- Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.
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2
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Lecomte F, Aerts J, Plenevaux A, Defraiteur C, Chapuis-Hugon F, Rozet E, Chiap P, Luxen A, Pichon V, Hubert P, Hubert C. Performance evaluation of a MIP for the MISPE-LC determination of p-[ 18F]MPPF and a potential metabolite in human plasma. J Pharm Biomed Anal 2020; 180:113015. [PMID: 31865206 DOI: 10.1016/j.jpba.2019.113015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 10/11/2019] [Accepted: 11/26/2019] [Indexed: 10/25/2022]
Abstract
Within the family of serotonin (5-HT) receptors, the 5-HT1A subtype is particularly interesting as it may be involved in various physiological processes or psychological disorders. The p-[18F]MPPF, a highly selective 5-HT1A antagonist, is used for in vivo studies in human or animal by means of positron emission tomography (PET) [1]. In order to selectively extract p-[18F]MPPF and its main metabolites from plasma, molecularly imprinted polymer (MIP) was prepared against these compounds by using the p-MPPF as template. For the control of the selectivity, non-imprinted polymer (NIP) was also synthesized without template. The MIP sorbent, packed in disposable extraction cartridges (DECs), was then evaluated as molecularly imprinted solid-phase extraction (MISPE) prior to the LC determination. The conditions of extraction were evaluated in order to obtain the highest selective retention of the p-[18F]MPPF and its metabolites on this MIP. The MIP selectivity was exploited in the loading and washing steps by adjusting the pH of plasma samples at a suitable value and by selecting mixtures for the washing step to limit the contribution of non-specific interactions. Other important parameters involved in the conditioning and elution steps were also studied. Finally, a pre-validation was carried out with optimal extraction conditions to demonstrate the performance of this MISPE-LC method as a generic method in the context of evaluation of new MISPE for p-[18F]MPPF and its potential for metabolites extraction from human plasma.
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Affiliation(s)
- F Lecomte
- University of Liège (ULiege), CIRM, Laboratory of Pharmaceutical Analytical Chemistry, Liège, Belgium
| | - J Aerts
- University of Liège (ULiege), GIGA-CRC In VIVO Imaging, Liège, Belgium
| | - A Plenevaux
- University of Liège (ULiege), GIGA-CRC In VIVO Imaging, Liège, Belgium
| | - C Defraiteur
- University of Liège (ULiege), GIGA-CRC In VIVO Imaging, Liège, Belgium
| | - F Chapuis-Hugon
- Dept of Analytical, Bioanalytical Sciences and Miniaturization (LSABM), UMR CBI 8231 (CNRS-ESPCI Paris), ESPCI Paris, PSL University, Paris, France
| | - E Rozet
- Pharmalex, Mont-St-Guibert, Belgium
| | - P Chiap
- Academic Hospital of Liège, Department of Toxicology, GLP-AEPT Unit, CIRM, Liège, Belgium
| | - A Luxen
- University of Liège (ULiege), GIGA-CRC In VIVO Imaging, Liège, Belgium
| | - V Pichon
- Dept of Analytical, Bioanalytical Sciences and Miniaturization (LSABM), UMR CBI 8231 (CNRS-ESPCI Paris), ESPCI Paris, PSL University, Paris, France; Sorbonne Université, Paris, France
| | - Ph Hubert
- University of Liège (ULiege), CIRM, Laboratory of Pharmaceutical Analytical Chemistry, Liège, Belgium
| | - C Hubert
- University of Liège (ULiege), CIRM, Laboratory of Pharmaceutical Analytical Chemistry, Liège, Belgium.
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Pauwelyn G, Vlerick L, Dockx R, Verhoeven J, Dobbeleir A, Peremans K, Goethals I, Bosmans T, Vanhove C, De Vos F, Polis I. PET quantification of [18F]MPPF in the canine brain using blood input and reference tissue modelling. PLoS One 2019; 14:e0218237. [PMID: 31185062 PMCID: PMC6559658 DOI: 10.1371/journal.pone.0218237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 05/30/2019] [Indexed: 12/04/2022] Open
Abstract
Numerous studies have shown that the serotonin1A (5-HT1A) receptor is implicated in the pathophysiology and treatment of several psychiatric and neurological disorders. Furthermore, functional imaging studies in a variety of species have demonstrated that 4-(2´-Methoxyphenyl)-1-[2´-(N-2´´-pyridinyl)-p- [18F]fluorobenzamidoethylpiperazine ([18F]MPPF) is a valid and useful PET tracer to visualize the 5HT1A receptor. However, to our knowledge, [18F]MPPF has never been demonstrated in the canine brain. The ability to image the 5HT1A receptor with PET in dogs could improve diagnosis and therapy in both canine and human behavioural and neuropsychiatric disorders. To examine the potential use of [18F]MPPF in dogs, five healthy adult laboratory beagles underwent a 60-minutes dynamic PET scan with [18F]MPPF while arterial blood samples were taken. For each region of interest, total distribution volume (VT) and corresponding binding potential (BPND) were calculated using the 1-tissue compartment model (1-TC), 2-Tissue compartment model (2-TC) and Logan plot. The preferred model was chosen based on the goodness-of-fit, calculated with the Akaike information criterium (AIC). Subsequently, the BPND values of the preferred compartment model were compared with the estimated BPND values using three reference tissue models (RTMs): the 2-step simplified reference tissue model (SRTM2), the 2-parameter multilinear reference tissue model (MRTM2) and the Logan reference tissue model. According to the lower AIC values of the 2-TC model compared to the 1-TC in all ROIs, the 2-TC model showed a better fit. Calculating BPND using reference tissue modelling demonstrated high correlation with the BPND obtained by metabolite corrected plasma input 2-TC. This first-in-dog study indicates the results of a bolus injection with [18F]MPPF in dogs are consistent with the observations presented in the literature for other animal species and humans. Furthermore, for future experiments, compartmental modelling using invasive blood sampling could be replaced by RTMs, using the cerebellum as reference region.
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Affiliation(s)
- Glenn Pauwelyn
- Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium
| | - Lise Vlerick
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Robrecht Dockx
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- Department of Psychiatry and Medical Psychology, Ghent University, Ghent, Belgium
| | | | - Andre Dobbeleir
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- Department of Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Kathelijne Peremans
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Ingeborg Goethals
- Department of Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Tim Bosmans
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Christian Vanhove
- Institute Biomedical Technology–Medisip–Infinity, Ghent University, Ghent, Belgium
| | - Filip De Vos
- Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium
| | - Ingeborgh Polis
- Small Animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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Erfani M, Malek H, Sadat Ebrahimi SE, Hassanzadeh L. New99mTc(CO)3-radiolabeled arylpiperazine pharmacophore as potent 5HT1Aserotonin receptor radiotracer: Docking studies, chemical synthesis, radiolabeling, and biological evaluation. J Labelled Comp Radiopharm 2019; 62:166-177. [DOI: 10.1002/jlcr.3709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 12/14/2018] [Accepted: 01/10/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Mostafa Erfani
- Radiation Application Research School; Nuclear Science and Technology Research Institute (NSTRI); Tehran Iran
| | - Hadi Malek
- Department of Nuclear Medicine and Molecular Imaging, Rajaie Cardiovascular, Medical, and Research Center; Iran University of Medical Sciences; Tehran Iran
| | | | - Leila Hassanzadeh
- Department of Nuclear Medicine, School of Medicine, Rajaie Cardiovascular, Medical & Research Center; Iran University of Medical Sciences; Tehran Iran
- Department of Medicinal Chemistry, School of Pharmacy-International Campus; Iran University of Medical Sciences; Tehran Iran
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Jha P, Chaturvedi S, Kaul A, Pant P, Anju A, Pal S, Jain N, Mishra AK. Design, physico-chemical and pre-clinical evaluation of a homo-bivalent 99mTc-(BTZ)2DTPA radioligand for targeting dimeric 5-HT1A/5-HT7 receptors. NEW J CHEM 2018. [DOI: 10.1039/c8nj00089a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A 99mTc-labelled bis-benzothiazolone-DTPA radio-complex as a SPECT neuroimaging agent.
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Affiliation(s)
- Preeti Jha
- Department of Chemistry
- Indian Institute of Technology Delhi (IITD)
- India
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
| | - Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Defence Research and Development Organization
- Delhi-110054
- India
| | - Ankur Kaul
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Defence Research and Development Organization
- Delhi-110054
- India
| | - Pradeep Pant
- Department of Chemistry
- Indian Institute of Technology Delhi (IITD)
- India
| | - Anju Anju
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Defence Research and Development Organization
- Delhi-110054
- India
| | - Sunil Pal
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Defence Research and Development Organization
- Delhi-110054
- India
| | - Nidhi Jain
- Department of Chemistry
- Indian Institute of Technology Delhi (IITD)
- India
| | - Anil K. Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences
- Institute of Nuclear Medicine and Allied Sciences
- Defence Research and Development Organization
- Delhi-110054
- India
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Yokoyama C, Mawatari A, Kawasaki A, Takeda C, Onoe K, Doi H, Newman-Tancredi A, Zimmer L, Onoe H. Marmoset Serotonin 5-HT1A Receptor Mapping with a Biased Agonist PET Probe 18F-F13714: Comparison with an Antagonist Tracer 18F-MPPF in Awake and Anesthetized States. Int J Neuropsychopharmacol 2016; 19:pyw079. [PMID: 27608810 PMCID: PMC5203761 DOI: 10.1093/ijnp/pyw079] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/05/2016] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND In vivo mapping by positron emission tomography of the serotonin 1A receptors has been hindered by the lack of suitable agonist positron emission tomography probes. 18F-labeled F13714 is a recently developed biased agonist positron emission tomography probe that preferentially targets subpopulations of serotonin 1A receptors in their "active state," but its brain labeling pattern in nonhuman primate has not been described. In addition, a potential confound in the translatability of PET data between nonhuman animal and human arise from the use of anesthetics that may modify the binding profiles of target receptors. METHODS Positron emission tomography scans were conducted in a cohort of common marmosets (n=4) using the serotonin 1A receptor biased agonist radiotracer, 18F-F13714, compared with a well-characterized 18F-labeled antagonist radiotracer, 18F-MPPF. Experiments on each animal were performed under both consciousness and isoflurane-anesthesia conditions. RESULTS 18F-F13714 binding distribution in marmosets by positron emission tomography differs markedly from that of the 18F-MPPF. Whereas 18F-MPPF showed highest binding in hippocampus and amygdala, 18F-F13714 showed highest labeling in other regions, including insular and cingulate cortex, thalamus, raphe, caudate nucleus, and putamen. The binding potential values of 18F-F13714 were about one-third of those observed with 18F-MPPF, with marked individual- and region-specific differences under isoflurane-anesthetized vs conscious conditions. CONCLUSIONS These findings highlight the importance of investigating the brain imaging of serotonin 1A receptors using agonist probes such as 18F-F13714, which may preferentially target subpopulations of serotonin 1A receptors in specific brain regions of nonhuman primate as a biased agonist.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hirotaka Onoe
- RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan (Dr Yokoyama, Ms Mawatari, Mr Kawasaki, Ms Takeda, Ms K. Onoe, Dr Doi, Dr H. Onoe); Neurolixis Inc, Dana Point, CA (Dr Newman-Tancredi); Université Claude Bernard Lyon 1, Hospices Civils de Lyon, INSERM, CNRS, Lyon Neuroscience Research Center, Lyon, France (Dr Zimmer).
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García G, Abet V, Alajarín R, Álvarez-Builla J, Delgado M, García-García L, Bascuñana-Almarcha P, Peña-Salcedo C, Kelly J, Pozo MA. N-(4-[(18)F]-fluoropyridin-2-yl)-N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}carboxamides as analogs of WAY100635. New PET tracers of serotonin 5-HT(1A) receptors. Eur J Med Chem 2014; 85:795-806. [PMID: 25171752 DOI: 10.1016/j.ejmech.2014.07.096] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 10/25/2022]
Abstract
N-(4-[(18)F]-Fluoropyridin-2-yl)-N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}-carboxamides were prepared by labeling their 4-nitropyridin-2-yl precursors through nitro substitution by the (18)F anion. In vitro and in vivo tests showed that the cyclohexanecarboxamide derivative is a reversible, selective and high affinity 5-HT1A receptor antagonist (IC50 = 0.29 nM, ki = 0.18 nM) with high brain uptake, slow brain clearance and stability to defluorination when compared with conventional standards. This PET radioligand is a promising candidate for an improved in vivo quantification of 5-HT1A receptors in neuropsychiatric disorders.
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Affiliation(s)
- Gonzalo García
- Departamento de Química Orgánica, Universidad de Alcalá, Alcalá de Henares, Madrid 28871, Spain
| | - Valentina Abet
- Departamento de Química Orgánica, Universidad de Alcalá, Alcalá de Henares, Madrid 28871, Spain
| | - Ramón Alajarín
- Departamento de Química Orgánica, Universidad de Alcalá, Alcalá de Henares, Madrid 28871, Spain
| | - Julio Álvarez-Builla
- Departamento de Química Orgánica, Universidad de Alcalá, Alcalá de Henares, Madrid 28871, Spain.
| | - Mercedes Delgado
- CAI Cartografía Cerebral, Instituto Pluridisciplinar UCM, Paseo Juan XXIII, 1, Madrid 28040, Spain
| | - Luis García-García
- CAI Cartografía Cerebral, Instituto Pluridisciplinar UCM, Paseo Juan XXIII, 1, Madrid 28040, Spain
| | - Pablo Bascuñana-Almarcha
- CAI Cartografía Cerebral, Instituto Pluridisciplinar UCM, Paseo Juan XXIII, 1, Madrid 28040, Spain
| | - Carmen Peña-Salcedo
- Instituto Tecnológico PET, Calle Manuel Bartolomé Cossío 10, Madrid 28040, Spain
| | - James Kelly
- Instituto Tecnológico PET, Calle Manuel Bartolomé Cossío 10, Madrid 28040, Spain
| | - Miguel A Pozo
- CAI Cartografía Cerebral, Instituto Pluridisciplinar UCM, Paseo Juan XXIII, 1, Madrid 28040, Spain; Instituto Tecnológico PET, Calle Manuel Bartolomé Cossío 10, Madrid 28040, Spain.
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Hassanzadeh L, Erfani M, Najafi R, Shafiei M, Amini M, Shafiee A, Ebrahimi SES. Synthesis, radiolabeling and bioevaluation of a novel arylpiperazine derivative containing triazole as a 5-HT1A receptor imaging agents. Nucl Med Biol 2012; 40:227-32. [PMID: 23141548 DOI: 10.1016/j.nucmedbio.2012.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 09/20/2012] [Accepted: 10/03/2012] [Indexed: 11/29/2022]
Abstract
INTRODUCTION It has been recognized that serotonin plays a main role in various pathological conditions such as anxiety, depression, aggressiveness, schizophrenia, suicidal behavior, panic and autism. 1-(2-Methoxyphenyl) piperazine pharmacophore, a fragment of the true 5-HT(1A) antagonist WAY100635, is found in numerous selective 5-HT(1A) imaging agents. In this paper, we have reported the synthesis of a novel derivative of 1-(2-methoxyphenyl) piperazine that is labeled with (99m)Tc (CO)(3) via click chemistry. METHODS The bidentate alkyne, propargylglycine was reacted with phenyl piperazine triazole derivative in the presence of a catalytic amount of Cu (I) to form tridentate ligand. The ligand was radiolabeled with the precursor [(99m)Tc] [(H(2)O)(3) (CO)(3)](+) and characterized by HPLC. The bioevaluation of radio labeled ligand was carried out in rats. RESULTS Triazole complex was labeled by (99m)Tc-tricarbonyl and its radiochemical yield was more than >95% which was determined by HPLC. In vivo stability studies in human serum albumin show a 93% ratio of complex after a 24h period. The calculated partition coefficient (logP) was 0.34±0.02. Receptor binding assays indicated about 70% specific binding of radioligand to 5-HT(1A) receptors. Biodistribution studies have shown brain hippocampus uptake of 0.40±0.08 %ID/g at 30 min post injection. CONCLUSIONS Results indicate that this (99m)Tc-tricabonyl-arylpiperazine derivative has specific binding to 5-HT(1A) receptors and presented suitable characters for its use as a CNS imaging agent.
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Affiliation(s)
- Leila Hassanzadeh
- Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
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9
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Al Hussainy R, Verbeek J, der Born DV, Molthoff C, Booij J, Herscheid J(KD. Synthesis, biodistribution and PET studies in rats of 18F-Labeled bridgehead fluoromethyl analogues of WAY-100635. Nucl Med Biol 2012; 39:1068-76. [DOI: 10.1016/j.nucmedbio.2012.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 04/10/2012] [Accepted: 04/15/2012] [Indexed: 10/28/2022]
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Abstract
The brain is one of the most protected organs in the body. There are two key barriers that control the access of endogenous substances and xenobiotics (drugs or toxins) to the CNS. These physiological structures are the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier. The BBB represents the main determinant of the effective delivery of drugs to the CNS. Good access through the BBB is essential if the target site is located within the CNS or, in contrast, can be a disadvantage if adverse reactions occur at central level. The development of new drugs targeted to the CNS requires a better knowledge of the factors affecting BBB permeation as well as in vitro and in silico predictive tools to optimize screening, and to reduce the attrition rate at later stages of drug development. This review discusses the particular characteristics of the biology and physiology of the BBB with respect to the permeation and distribution of drugs into the brain. The factors affecting rate, extent and distribution into the brain are discussed and a brief description of the in silico, in vitro, in situ and in vivo methods used to measure BBB transport are presented. Finally, the lastest proposals and strategies to enhance transport across the BBB of new CNS drugs are summarized.
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Discrepancies in the P-glycoprotein-mediated transport of (18)F-MPPF: a pharmacokinetic study in mice and non-human primates. Pharm Res 2012; 29:2468-76. [PMID: 22644589 DOI: 10.1007/s11095-012-0776-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/09/2012] [Indexed: 01/15/2023]
Abstract
PURPOSE Several in vivo studies have found that the 5-HT(1A) PET radioligand (18)F-MPPF is a substrate of rodent P-glycoprotein (P-gp). However, in vitro assays suggest that MPPF is not a substrate of human P-gp. We have now tested the influence of inhibiting P-gp on the brain kinetics of (18)F-MPPF in mice and non-human primates. METHODS We measured the peripheral kinetics (arterial input function, metabolism, free fraction in plasma (f(P))) during (18)F-MPPF brain PET scanning in baboons with or without cyclosporine A (CsA) infusion. We measured (3)H-MPPF transport at the mouse BBB using in situ brain perfusion in P-gp/Bcrp deficient mice and after inhibiting P-gp with PSC833. RESULTS There was an unexpected 1.9-fold increase in brain area under the curve in CsA-treated baboons (n = 4), with no change in radiometabolite-corrected arterial input. However, total volume of distribution corrected for f(P) (V(T)/f(P)) remained unchanged. In situ brain perfusion showed that P-gp restricted the permeability of the mouse BBB to (3)H-MPPF while Bcrp did not. CONCLUSION These and previous in vitro results suggest that P-gp may not influence the permeability of human BBB to (18)F-MPPF. However, CsA treatment increased (18)F-MPPF free fraction, which is responsible for a misleading, P-gp unrelated enhanced brain uptake.
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Design, synthesis and in vitro evaluation of bridgehead fluoromethyl analogs of N-{2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl}-N-(pyridin-2-yl)cyclohexanecarboxamide (WAY-100635) for the 5-HT1A receptor. Eur J Med Chem 2011; 46:5728-35. [DOI: 10.1016/j.ejmech.2011.06.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/10/2011] [Accepted: 06/16/2011] [Indexed: 11/19/2022]
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13
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Xi W, Tian M, Zhang H. Molecular imaging in neuroscience research with small-animal PET in rodents. Neurosci Res 2011; 70:133-43. [PMID: 21241748 DOI: 10.1016/j.neures.2010.12.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 12/21/2010] [Accepted: 12/24/2010] [Indexed: 10/18/2022]
Abstract
Cognitive neuroscience, which studies the biological basis of mental processes, widely uses neuroimaging technologies like functional magnetic resonance imaging and positron emission tomography (PET) to study the human brain. Small laboratory animals, like rodents, are commonly used in brain research and provide abundant models of human brain diseases. The development of high-resolution small-animal PET and various radiotracers together with sophisticated methods for analyzing functional brain imaging data have accelerated research on brain function and neurotransmitter release during behavioral tasks in rodents. In this review, we first summarize advances in the methodology of cognitive research brought about by the development of sophisticated methods for whole-brain imaging analysis and improvements in neuroimaging protocols. Then, we discuss basic mechanisms related to metabolic changes and the expression of neurotransmitters in various brain areas during task-induced neural activity. In particular, we discuss glucose metabolism imaging and brain receptor imaging for various receptor systems. Finally, we discuss the current status and future perspectives. Mechanisms of neurotransmitter expression will probably become an increasingly important field of study in the future, leading to more collaboration between investigators in fields such as computational and theoretical neuroscience.
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Affiliation(s)
- Wang Xi
- Department of Nuclear Medicine, Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, China
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14
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Herth MM, Kramer V, Rösch F. Synthesis of novel WAY 100635 derivatives containing a norbornene group and radiofluorination of [18F]AH1.MZ as a serotonin 5-HT1Areceptor antagonist for molecular imaging. J Labelled Comp Radiopharm 2009. [DOI: 10.1002/jlcr.1589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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MicroPET imaging of 5-HT 1A receptors in rat brain: a test-retest [18F]MPPF study. Eur J Nucl Med Mol Imaging 2008; 36:53-62. [PMID: 18704404 DOI: 10.1007/s00259-008-0891-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE Earlier studies have shown that positron emission tomography (PET) imaging with the radioligand [(18)F]MPPF allows for measuring the binding potential of serotonin 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in different regions of animal and human brain, including that of 5-HT(1A) autoreceptors in the raphe nuclei. In the present study, we sought to determine if such data could be obtained in rat, with a microPET (R4, Concorde Microsystems). METHODS Scans from isoflurane-anaesthetised rats (n = 18, including six test-retest) were co-registered with magnetic resonance imaging data, and binding potential, blood to plasma ratio and radiotracer efflux were estimated according to a simplified reference tissue model. RESULTS Values of binding potential for hippocampus (1.2), entorhinal cortex (1.1), septum (1.1), medial prefrontal cortex (1.0), amygdala (0.8), raphe nuclei (0.6), paraventricular hypothalamic nucleus (0.5) and raphe obscurus (0.5) were comparable to those previously measured with PET in cats, non-human primates or humans. Test-retest variability was in the order of 10% in the larger brain regions (hippocampus, medial prefrontal and entorhinal cortex) and less than 20% in small nuclei such as the septum and the paraventricular hypothalamic, basolateral amygdaloid and raphe nuclei. CONCLUSIONS MicroPET brain imaging of 5-HT(1A) receptors with [(18)F]MPPF thus represents a promising avenue for investigating 5-HT(1A) receptor function in rat.
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Laćan G, Plenevaux A, Rubins DJ, Way BM, Defraiteur C, Lemaire C, Aerts J, Luxen A, Cherry SR, Melega WP. Cyclosporine, a P-glycoprotein modulator, increases [18F]MPPF uptake in rat brain and peripheral tissues: microPET and ex vivo studies. Eur J Nucl Med Mol Imaging 2008; 35:2256-66. [PMID: 18604533 DOI: 10.1007/s00259-008-0832-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Accepted: 05/02/2008] [Indexed: 12/20/2022]
Abstract
PURPOSE Pretreatment with cyclosporine, a P-glycoprotein (P-gp) modulator increases brain uptake of 4-(2'-methoxyphenyl)-1-[2'-(N-2"-pyridinyl)-p-[(18)F]fluorobenzamido]ethylpiperazine ([(18)F]MPPF) for binding to hydroxytryptamine(1A) (5-HT(1A)) receptors. Those increases were quantified in rat brain with in vivo microPET and ex vivo tissue studies. MATERIALS AND METHODS Each Sprague-Dawley rat (n = 4) received a baseline [(18)F]MPPF microPET scan followed by second scan 2-3 weeks later that included cyclosporine pretreatment (50 mg/kg, i.p.). Maximum a posteriori reconstructed images and volumetric ROIs were used to generate dynamic radioactivity concentration measurements for hippocampus, striatum, and cerebellum, with simplified reference tissue method (SRTM) analysis. Western blots were used to semiquantify P-gp regional distribution in brain. RESULTS MicroPET studies showed that hippocampus uptake of [(18)F]MPPF was increased after cyclosporine; ex vivo studies showed similar increases in hippocampus and frontal cortex at 30 min, and for heart and kidney at 2.5 and 5 min, without concomitant increases in [(18)F]MPPF plasma concentration. P-gp content in cerebellum was twofold higher than in hippocampus or frontal cortex. CONCLUSIONS These studies confirm and extend prior ex vivo results (J. Passchier, et al., Eur J Pharmacol, 2000) that showed [(18)F]MPPF as a substrate for P-gp. Our microPET results showed that P-gp modulation of [(18)F]MPPF binding to 5-HT(1A) receptors can be imaged in rat hippocampus. The heterogeneous brain distribution of P-gp appeared to invalidate the use of cerebellum as a nonspecific reference region for SRTM modeling. Regional quantitation of P-gp may be necessary for accurate PET assessment of 5-HT(1A) receptor density when based on tracer uptake sensitive to P-gp modulation.
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Affiliation(s)
- Goran Laćan
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA 90095-1735, USA
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17
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In vivo quantification of 5-HT1A–[18F]MPPF interactions in rats using the YAP-(S)PET scanner and a β-microprobe. Neuroimage 2008; 41:823-34. [DOI: 10.1016/j.neuroimage.2008.02.062] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 01/28/2008] [Accepted: 02/28/2008] [Indexed: 11/20/2022] Open
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Desbrée A, Verdurand M, Godart J, Dubois A, Mastrippolito R, Pain F, Pinot L, Delzescaux T, Gurden H, Zimmer L, Lanièce P. The Potential of a Radiosensitive Intracerebral Probe to Monitor 18F-MPPF Binding in Mouse Hippocampus In Vivo. J Nucl Med 2008; 49:1155-61. [DOI: 10.2967/jnumed.107.050047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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19
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Desbrée A, Rbah L, Langlois JB, Grenier D, Mastrippolito R, Pain F, Pinot L, Lanièce P, Zimmer L, Gurden H. Simultaneous in vivo magnetic resonance imaging and radioactive measurements with the beta-MicroProbe. Eur J Nucl Med Mol Imaging 2007; 34:1868-72. [PMID: 17594091 DOI: 10.1007/s00259-007-0475-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 04/12/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE Multimodal instrumentation is a new technical approach allowing simultaneous and complementary in vivo recordings of complementary biological parameters. To elucidate further the physiopathological mechanisms in intact small animal models, especially for brain studies, a challenging issue is the actual coupling of magnetic resonance imaging (MRI) techniques with positron emission tomography (PET): it has been shown that running the technology for radioactive imaging in a magnet alters the spatiotemporal performance of both modalities. Thus, we propose an alternative coupling of techniques that uses the beta-MicroProbe instead of PET for local measurements of radioactivity coupled with MRI. METHODS We simultaneously recorded local radioactivity due to [(18)F]MPPF (a 5-HT(1A) receptor PET radiotracer) binding in the hippocampus with the beta-MicroProbe and carried out anatomical MRI in the same anaesthetised rat. RESULTS The comparison of [(18)F]MPPF kinetics obtained from animals in a magnet with kinetics from a control group outside the magnet allowed us to determine the stability of tracer biokinetic measurements over time in the magnet. We were thus able to show that the beta-MicroProbe reliably measures radioactivity in rat brains under an intense magnetic field of 7 Tesla. CONCLUSION The biological validation of a beta-MicroProbe/MRI dual system reported here opens up a wide range of future multimodal approaches for functional and pharmacological measurements by the probe combined with various magnetic resonance technologies, including anatomical MRI, functional MRI and MR spectroscopy.
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Affiliation(s)
- A Desbrée
- IRSN, BP 17, 92262, Fontenay aux roses, France.
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20
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Aznavour N, Zimmer L. [18F]MPPF as a tool for the in vivo imaging of 5-HT1A receptors in animal and human brain. Neuropharmacology 2006; 52:695-707. [PMID: 17101155 DOI: 10.1016/j.neuropharm.2006.09.023] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Revised: 09/21/2006] [Accepted: 09/29/2006] [Indexed: 11/18/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and its various receptors are involved in numerous CNS functions and psychiatric disorders. 5-HT(1A), the best-characterized subtype of currently known 5-HT receptors, is tightly implicated in the pathogenesis of depression, anxiety, epilepsy and eating disorders. It thus represents an important target for drug therapy. Specific radioligands and positron emission tomography (PET) allow for a quantitative imaging of brain 5-HT(1A) receptor distribution in living animals and humans. Recently, the selective 5-HT(1A) receptor antagonist, MPPF, has been successfully labeled with [(18)F]fluorine ([(18)F]MPPF), and an increasing number of academic and industry centres have used this radiotracer in preclinical and clinical studies. After a brief account of some of the structural, distributional and electrophysiological characteristics of brain 5-HT(1A) receptors, this review focuses on studies conducted with [(18)F]MPPF, with emphasis on preclinical results illustrating the actual and potential value of this PET radioligand for clinical research and drug development.
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Affiliation(s)
- Nicolas Aznavour
- Laboratoire de Neuropharmacologie, Université Lyon 1, Lyon, France
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21
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Nicolazzo JA, Charman SA, Charman WN. Methods to assess drug permeability across the blood-brain barrier. J Pharm Pharmacol 2006; 58:281-93. [PMID: 16536894 DOI: 10.1211/jpp.58.3.0001] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Much research has focussed on the development of novel therapeutic agents to target various central nervous system disorders, however less attention has been given to determining the potential of such agents to permeate the blood-brain barrier (BBB), a factor that will ultimately govern the effectiveness of these agents in man. In order to assess the potential for novel compounds to permeate the BBB, various in-vitro, in-vivo and in-silico methods may be employed. Although in-vitro models (such as primary cell culture and immortalized cell lines) are useful as a screening method and can appropriately rank compounds in order of BBB permeability, they often correlate poorly to in-vivo brain uptake due to down-regulation of some BBB-specific transporters. In-vivo models (such as the internal carotid artery single injection or perfusion, intravenous bolus injection, brain efflux index and intracerebral microdialysis) provide more accurate information regarding brain uptake, and these can be complemented with novel imaging techniques (such as magnetic resonance imaging and positron emission tomography), although such methods are not suited to high-throughput permeability assessment. This paper reviews current methods used for assessing BBB permeability and highlights the particular advantages and disadvantages associated with each method, with a particular focus on methods suitable for moderate- to high-throughput screening.
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Affiliation(s)
- Joseph A Nicolazzo
- Centre for Drug Candidate Optimisation, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
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Defraiteur C, Lemaire C, Luxen A, Plenevaux A. Radiochemical synthesis and tissue distribution of p-[18F]DMPPF, a new 5-HT1A ligand for PET, in rats. Nucl Med Biol 2006; 33:667-75. [PMID: 16843842 DOI: 10.1016/j.nucmedbio.2006.03.010] [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] [Received: 03/03/2006] [Revised: 03/16/2006] [Accepted: 03/31/2006] [Indexed: 10/24/2022]
Abstract
Several studies have demonstrated the potential of p-[(18)F]MPPF as a radiopharmaceutical to study the 5-HT(1A) receptor family in animals and humans. A structural modification leading to a higher radioactive signal at an equipotent dose would greatly enhance this potential. With this goal, the desmethylated 4-(2'-methoxyphenyl)-1-[2'-[N-(2''-pyridinyl)-p-fluorobenzamido]ethyl]-piperazine (p-MPPF), identified as p-DMPPF, was synthesized, labeled with fluorine-18 and evaluated through ex vivo tissue distribution in rats. The new compounds p-DMPPF, p-DMPPNO(2), MEM-p-MPPF and MEM-p-MPPNO(2) were isolated and fully identified ((1)H and (13)C NMR, LC-MS). The final compound, p-[(18)F]DMPPF, was obtained ready for injection, with an overall radiochemical yield of 10% (EOB corrected) within 90 min and a specific activity of 62 GBq/mumol. Tissue distributions showed that the carbon-fluorine bond was stable in vivo and that this compound could cross the blood-brain barrier. For kidney, lung, heart, spleen, bone, testicle, liver and muscle, the percentage of injected dose per gram of tissue obtained with p-[(18)F]DMPPF was of the same order of magnitude as that of p-[(18)F]MPPF. The amount of radioactivity reaching the brain was much higher (approximately fivefold at 60 min) for p-[(18)F]DMPPF compared with p-[(18)F]MPPF, which was taken as reference. The distribution and specificity were in total agreement with the known localization of 5-HT(1A) receptors in rats. The radioactivity increase was more important for specific tissues (hippocampus and frontal cortex) than for cerebellum or striatum, leading to better contrast (hippocampus/cerebellum=5.8 at 60 min). The levels of metabolites found in plasma showed that p-[(18)F]DMPPF appears to be less metabolized than p-[(18)F]MPPF. p-[(18)F]DMPPF deserves further evaluation as a radiopharmaceutical candidate.
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Affiliation(s)
- Caroline Defraiteur
- Cyclotron Research Center, Liege University, Sart Tilman B.30, B-4000 Liege, Belgium
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Udo de Haes JI, Harada N, Elsinga PH, Maguire RP, Tsukada H. Effect of fenfluramine-induced increases in serotonin release on [18F]MPPF binding: a continuous infusion PET study in conscious monkeys. Synapse 2006; 59:18-26. [PMID: 16237679 DOI: 10.1002/syn.20209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
[(18)F]MPPF is a selective and reversible antagonist to the serotonin-1A (5-HT(1A)) receptor. The aim of the present study was to investigate whether the binding of [(18)F]MPPF is sensitive to increases in 5-HT levels. We used the 5-HT releasing agent and reuptake inhibitor fenfluramine (FEN) to increase the concentration of 5-HT. [(18)F]MPPF binding was assessed using positron emission tomography (PET) in conscious monkeys. Possible effects of blood flow on ligand binding were excluded by using a bolus-infusion paradigm. Control scans were obtained to assess the state of ligand equilibrium. FEN (5 or 10 mg/kg, i.v.) was administered between 90 and 130 min after the start of the [(18)F]MPPF infusion. The binding potential (BP) was calculated for an early interval (30 min preceding FEN administration) and late interval (20-50 min after administration of FEN). Microdialyses results showed a 20- and 35-fold increase in extracellular 5-HT levels in the prefrontal cortex after injection of FEN at a dose of 5 mg/kg and 10 mg/kg respectively. However, despite these large increases in 5-HT levels, no differences in BP were found between the control and FEN scans. These results may imply that the majority of 5-HT(1A) receptors is in the low affinity state in the living brain.
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Affiliation(s)
- Joanna I Udo de Haes
- Department of Biological Psychiatry, University Medical Center Groningen, The Netherlands.
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Aznavour N, Rbah L, Léger L, Buda C, Sastre JP, Imhof A, Charnay Y, Zimmer L. A comparison of in vivo and in vitro neuroimaging of 5-HT1A receptor binding sites in the cat brain. J Chem Neuroanat 2006; 31:226-32. [PMID: 16517120 DOI: 10.1016/j.jchemneu.2006.01.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 01/30/2006] [Accepted: 01/30/2006] [Indexed: 10/24/2022]
Abstract
To validate the cat as a suitable model for positron emission tomography imaging (PET) and to gain further knowledge on the anatomical distribution of the serotonin-1A receptor (5-HT 1A) in the feline brain, we used PET with [18F]MPPF and in vitro autoradiography with [3H]MPPF, [3H]8-OH-DPAT and [3H]paroxetine. PET radioactivity curves with [18F]MPPF were very reproducible in anaesthetized cats, with the highest radioactivity uptakes recorded in the hippocampus, cingulate cortex, septum, infralimbic cortex and raphe nucleus, whereas the lowest were found in the cerebellum. [3H]8-OH-DPAT binding displayed a comparable, albeit lower, regional distribution than with [3H]MPPF. Autoradiography also revealed the presence of 5-HT 1A receptor binding sites in the cortex and in the interpeduncular nucleus, due to its greater sensitivity and spatial resolution compared with PET imaging. The cat constitutes an interesting experimental model for PET imaging, as many physiological concepts have been well established with this animal. Our study also shows the advantages of combining complementary neuroimaging techniques such as in vivo PET imaging and in vitro autoradiography to visualize the distribution of the 5-HT 1A receptors.
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25
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Udo de Haes JI, Cremers TIFH, Bosker FJ, Postema F, Tiemersma-Wegman TD, den Boer JA. Effect of increased serotonin levels on [18F]MPPF binding in rat brain: fenfluramine vs the combination of citalopram and ketanserin. Neuropsychopharmacology 2005; 30:1624-31. [PMID: 15827572 DOI: 10.1038/sj.npp.1300721] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
[18F]MPPF is a selective serotonin-1A (5-HT1A) receptor antagonist and may be used to measure changes in the functional levels of serotonin (5-HT). The technique is based on the assumption that the injected radiolabeled ligand competes for the same receptor as the endogenous transmitter. Results from studies using serotonergic ligands are not always consistent. The aim of the present study was to investigate if [18F]MPPF binding is decreased after an increase in 5-HT levels. [18F]MPPF binding was assessed in conscious rats using ex vivo autoradiography. We studied the effect of the 5-HT-releasing agent and reuptake inhibitor fenfluramine (10 mg/kg i.p.) and of a combination of the selective serotonin reuptake inhibitor (SSRI) citalopram (10 micromol/kg, s.c.) with the 5-HT2C antagonist ketanserin (100 nmol/kg, s.c). The effect of both treatments on extracellular 5-HT levels was determined using microdialysis. Fenfluramine treatment resulted in a 30-fold increase in extracellular 5-HT levels in the ventral hippocampus and induced a significant reduction of [18F]MPPF binding in the frontal cortex, hypothalamus, amygdala, and hippocampus. The microdialysis results showed a 10-fold 5-HT increase in the ventral hippocampus after combined administration of ketanserin and citalopram. The combination, however, did not affect [18F]MPPF binding. Our data show that [18F]MPPF binding in conscious rats is only reduced after substantial and therefore nonphysiological increases in 5-HT levels. These results may imply that the majority of 5-HT1A receptors is in the low-affinity state, in vivo.
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Affiliation(s)
- Joanna I Udo de Haes
- Department of Biological Psychiatry, University Medical Center Groningen, Groningen, The Netherlands.
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26
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Simmons MK, Manjeshwar R, Agdeppa ED, Mattheyses RM, Kiehl TR, Montalto MC. A Computational Positron Emission Tomography Simulation Model for Imaging ?-Amyloid in Mice. Mol Imaging Biol 2005; 7:69-77. [PMID: 15912278 DOI: 10.1007/s11307-005-0952-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE We aimed to develop a computational simulation model for beta-amyloid (Abeta) positron emission tomography (PET) imaging. PROCEDURES Model parameters were set to reproduce levels of Abeta within the PDAPP mouse. Pharmacokinetic curves of virtual tracers were computed and a PET detector simulator was configured for a commercially available preclinical PET-imaging system. RESULTS We modeled the effects of Abeta therapy and tracer affinity on the ability to differentiate Abeta levels by PET. Varying affinity had a significant effect on the ability to quantitate Abeta. Further, PET tracers for Abeta monomers were more sensitive to the therapeutic reduction in Abeta levels than total brain amyloid. Following therapy, the decrease in total brain Abeta corresponded to the slow rate of change in total amyloid load as expected. CONCLUSIONS We have developed a first proof-of-concept Abeta-PET simulation model that will be a useful tool in the interpretation of preclinical Abeta imaging data and tracer development.
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Affiliation(s)
- Melvin K Simmons
- Bioinformatics Laboratory, Molecular Medicine and Biotechnology Program, GE Global Research Center, Niskayuna, NY 12309, USA
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27
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Praschak-Rieder N, Hussey D, Wilson AA, Carella A, Lee M, Dunn E, Willeit M, Bagby RM, Houle S, Meyer JH. Tryptophan depletion and serotonin loss in selective serotonin reuptake inhibitor-treated depression: an [(18)F] MPPF positron emission tomography study. Biol Psychiatry 2004; 56:587-91. [PMID: 15476688 DOI: 10.1016/j.biopsych.2004.07.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Revised: 07/09/2004] [Accepted: 07/19/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND Recurrence of depressive symptoms after tryptophan depletion (TD) in selective serotonin reuptake inhibitor (SSRI)-treated depression is an important, unexplained phenomenon. With [(18)F] MPPF positron emission tomography (PET), serotonin (5-hydroxytryptamine, 5-HT) 1A receptor binding potential (5-HT(1A)BP) was measured after TD in various brain regions in citalopram-treated depression. This 5-HT(1A)BP measurement is sensitive to changes in extracellular 5-HT in animal models. METHODS Eight remitted patients with major depressive disorder received [(18)F] MPPF PET scans twice: once after TD and once after sham depletion. Behavioral measures were evaluated with the Hamilton Depression Rating Scale and visual analog scales. RESULTS No effect on regional 5-HT(1A)BP was observed after TD, despite an 86% decrease in total plasma tryptophan and transient depressive relapse in six of eight patients. CONCLUSIONS Large-magnitude changes in extracellular 5-HT are not crucial for the mood effects observed in SSRI-treated subjects after TD. Therefore, greater consideration must be given to other mechanisms that involve vulnerability to small perturbations in extracellular 5-HT, such as impairment of signal transduction.
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Affiliation(s)
- Nicole Praschak-Rieder
- Vivian M. Rakoff PET Imaging Centre and the Mood and Anxiety Disorders Division, Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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28
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Winnard P, Raman V. Real time non-invasive imaging of receptor-ligand interactions in vivo. J Cell Biochem 2004; 90:454-63. [PMID: 14523979 DOI: 10.1002/jcb.10616] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Non-invasive longitudinal detection and evaluation of gene expression in living animals can provide investigators with an understanding of the ontogeny of a gene's biological function(s). Currently, mouse model systems are used to optimize magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and optical imaging modalities to detect gene expression and protein function. These molecular imaging strategies are being developed to assess tumor growth and the tumor microenvironment. In addition, pre-labeling of progenitor cells can provide invaluable information about the developmental lineage of stem cells both in organogenesis and tumorigenesis. The feasibility of this approach has been extensively tested by targeting of endogenous tumor cell receptors with labeled ligand (or ligand analog) reporters and targeting enzymes with labeled substrate (or substrate analog). We will primarily discuss MRI, PET, and SPECT imaging of cell surface receptors and the feasibility of non-invasive imaging of gene expression using the tumor microenvironment (e.g., hypoxia) as a conditional regulator of gene expression.
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MESH Headings
- Animals
- Antibodies, Anti-Idiotypic/immunology
- Carrier Proteins/metabolism
- Folate Receptors, GPI-Anchored
- Gene Expression Regulation
- Humans
- Ligands
- Magnetic Resonance Imaging
- Mice
- Models, Molecular
- Promoter Regions, Genetic/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Somatostatin/metabolism
- Receptors, Transferrin/metabolism
- Tomography, Emission-Computed
- Tomography, Emission-Computed, Single-Photon
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Affiliation(s)
- Paul Winnard
- Department of Radiology, MRI Division, Johns Hopkins University, Traylor 340, 720 Rutland Avenue, Baltimore, Maryland 21205-2196, USA
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Zimmer L, Riad M, Rbah L, Belkacem-Kahlouli A, Le Bars D, Renaud B, Descarries L. Toward brain imaging of serotonin 5-HT1A autoreceptor internalization. Neuroimage 2004; 22:1421-6. [PMID: 15219613 DOI: 10.1016/j.neuroimage.2004.03.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 03/09/2004] [Accepted: 03/11/2004] [Indexed: 11/29/2022] Open
Abstract
Enhancing cerebral serotonin (5-hydroxytryptamine, 5-HT) neurotransmission is a common property of antidepressant treatments and the basis for their efficacy. 5-HT1A receptors located on the cell body and dendrites of 5-HT neurons (autoreceptors) play a key role in this regard. Because they normally mediate an inhibition of neuronal firing, their desensitization is a prerequisite to the delayed enhancement of 5-HT neurotransmission upon treatment with monoamine oxidase (MAOI) inhibitors or specific serotonin reuptake inhibitors (SSRI). Using beta-sensitive microprobes in vivo, we measured a significant decrease (-30%) in binding sites for the 5-HT1A PET radioligand [18F]MPPF associated with an equivalent reduction (-34%) in the cell surface density of 5-HT1A receptor immunoreactivity (internalization), in the nucleus raphe dorsalis (autoreceptors), but not hippocampus (heteroreceptors), of rats given a single dose of the specific 5-HT1A receptor agonist, 8-OH-DPAT (0.5 mg/kg, iv). This effect was completely blocked by pretreatment with the selective 5-HT1A antagonist WAY 100635. Having ruled out that this decreased density of [18F]MPPF binding in the nucleus raphe dorsalis of 8-OH-DPAT-treated rats resulted from a local blood flow effect, we obtained autoradiographic evidence indicating that the total amount of specific binding of [18F]MPPF in tissue sections was unaffected by the 8-OH-DPAT treatment in either NRD or hippocampus. It was therefore concluded that the internalization of 5-HT1A autoreceptors accounted for the decreased binding in vivo of [18F]MPPF in the nucleus raphe dorsalis of rats treated with 8-OH-DPAT. Thus, PET imaging might provide a mean to measure 5-HT1A receptor internalization in human brain and thus assess responsiveness to antidepressant treatment.
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Affiliation(s)
- L Zimmer
- Laboratoire de Neuropharmacologie et Neurochimie, INSERM U512, Université Claude Bernard, Lyon, France.
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30
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Rbah L, Leviel V, Zimmer L. Displacement of the PET ligand 18F-MPPF by the electrically evoked serotonin release in the rat hippocampus. Synapse 2003; 49:239-45. [PMID: 12827643 DOI: 10.1002/syn.10235] [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: 11/10/2022]
Abstract
The effects of the electrically evoked serotonin release were evaluated on the binding of (18)F-MPPF in the hippocampus of anesthetized rats. The specific binding of (18)F-MPPF was measured by an implanted beta-microprobe and the serotonin (5-HT) extracellular concentration was measured by microdialysis under the same conditions. Our results showed that the 10-, 20-, or 30-min electrical stimulation of the raphe nucleus elicited a significant increase in extracellular 5-HT, only detectable in the presence of a 5-HT reuptake inhibitor in the perfusate (5 microM clomipramine). Interestingly, the raphe stimulations were associated with a 27-76% reversible decrease of the (18)F-MPPF specific binding in the hippocampus, but an unchanged extracellular (18)F-MPPF collected in dialysates. Considered together, these observations suggest that (18)F-MPPF binding is sensitive to 5-HT released at a neuronal level. This compartment, explored by the beta-microprobe, is probably distinct from the extracellular compartment, explored by microdialysis.
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Affiliation(s)
- Latifa Rbah
- CERMEP Biomedical Cyclotron, 59 boulevard Pinel, F-69003 Lyon, France
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31
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Karramkam M, Hinnen F, Berrehouma M, Hlavacek C, Vaufrey F, Halldin C, McCarron JA, Pike VW, Dollé F. Synthesis of a [6-pyridinyl-18F]-labelled fluoro derivative of WAY-100635 as a candidate radioligand for brain 5-HT1A receptor imaging with PET. Bioorg Med Chem 2003; 11:2769-82. [PMID: 12788351 DOI: 10.1016/s0968-0896(03)00225-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In recent years, considerable effort has been spent on the design, synthesis and pharmacological characterization of radiofluorinated derivatives of the 5-HT(1A) receptor antagonist, WAY-100635, for the in vivo study of these receptors in human brain with PET. (Pyridinyl-6)-fluoro- and (pyridinyl-5)-fluoro-analogues of WAY-100635 (6-fluoro and 5-fluoro-WAY-100635, 5a/6a) were synthesized as well as the corresponding chloro-, bromo- and nitro-derivatives as precursors for labelling (5b-d and 6b-d). Comparative radiolabelling of these precursors with fluorine-18 (positron-emitting isotope, 109.8 min half-life) clearly demonstrated that only ortho-fluorination in this pyridine series, and not meta-fluorination, is of interest for the preparation of a radioligand by nucleophilic heteroaromatic substitution. 6-[(18)F]Fluoro-WAY-100635 ([(18)F]5a) can be efficiently synthesized in one step, either from the corresponding 6-bromo precursor (using conventional heating at 145 degrees C for 10 min) or from the corresponding 6-nitro precursor (using microwave activation at 100 W for 1 min). Typically, 15-25 mCi (0.55-0.92 GBq) of 6-[(18)F]fluoro-WAY-100635 ([(18)F]5a, 1-2 Ci/micromol or 37-72 GBq/micromol) were obtained in 50-70 min starting from a 100 mCi (3.7 GBq) aliquot of a batch of cyclotron-produced [(18)F]fluoride. This (18)F-labelled radioligand is now being evaluated in PET studies.
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Affiliation(s)
- Mylène Karramkam
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale, CEA, 4 place du Général Leclerc, F-91401 Orsay, France
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32
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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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33
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Costes N, Merlet I, Zimmer L, Lavenne F, Cinotti L, Delforge J, Luxen A, Pujol JF, Le Bars D. Modeling [18 F]MPPF positron emission tomography kinetics for the determination of 5-hydroxytryptamine(1A) receptor concentration with multiinjection. J Cereb Blood Flow Metab 2002; 22:753-65. [PMID: 12045674 DOI: 10.1097/00004647-200206000-00014] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The selectivity of [18F]MPPF (fluorine-18-labeled 4-(2;-methoxyphenyl)-1-[2;-(N-2"-pirydynyl)-p-fluorobenzamido]ethylpiperazine) for serotonergic 5-hydroxytryptamine(1A) (5-HT1A) receptors has been established in animals and humans. The authors quantified the parameters of ligand-receptor exchanges using a double-injection protocol. After injection of a tracer and a coinjection dose of [18F]MPPF, dynamic positron emission tomography (PET) data were acquired during a 160-minute session in five healthy males. These PET and magnetic resonance imaging data were coregistered for anatomical identification. A three-compartment model was used to determine six parameters: Fv (vascular fraction), K1, k2 (plasma/free compartment exchange rate), koff, kon/Vr (association and dissociation rate), Bmax (receptor concentration), and to deduce Kd (apparent equilibrium dissociation rate). The model was fitted with regional PET kinetics and arterial input function corrected for metabolites. Analytical distribution volume and binding potential were compared with indices generated by Logan-Patlak graphical analysis. The 5HT1A specificity for MPPF was evidenced. A Bmax of 2.9 pmol/mL and a Kd of 2.8 nmol/L were found in hippocampal regions, Kd and distribution volume in the free compartment were regionally stable, and the Logan binding potential was linearly correlated to Bmax. This study confirms the value of MPPF in the investigation of normal and pathologic systems involving the limbic network and 5-HT1A receptors. Standard values can be used for the simulation of simplified protocols.
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Affiliation(s)
- Nicolas Costes
- Centre d'Exploration et de Recherche Médicales par Emission de Positons, Lyon, France.
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34
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Van Bogaert P, De Tiège X, Vanderwinden JM, Damhaut P, Schiffmann SN, Goldman S. Comparative study of hippocampal neuronal loss and in vivo binding of 5-HT1a receptors in the KA model of limbic epilepsy in the rat. Epilepsy Res 2001; 47:127-39. [PMID: 11673027 DOI: 10.1016/s0920-1211(01)00301-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A high density of 5-HT1a receptors is present in pyramidal hippocampal cells. Mapping of these receptors may be performed in vivo using the tracer no-carrier-added 4-(18)F-fluoro-N-2-(1-(2-methoxyphenyl)-1-piperazinyl)ethyl-N-2-pyridinyl-benzamide (MPPF). We tested the hypothesis of a relationship between MPPF binding and post-epileptic neuronal loss in the hippocampus. The model of limbic epilepsy induced by kainic acid (KA) in the rat was used. Rats were sacrificed at various times (1 h-240 days) after systemic injection of 10 mg/kg KA. Determination of MPPF binding in the brain was combined with a quantification of neuronal loss using DNA labeling with propidium iodide and confocal microscopy. Hippocampal MPPF binding varied according to time elapsed from KA injection. An initial decrease from day 1 to day 6 post injection was followed by a relative increase between day 6 and day 30. This effect was observed in rats which showed hippocampal neuronal loss but also in one rat which did not. In KA treated rats, statistically significant relationship between MPPF binding and neuronal count was found during the acute period (rats sacrificed 1 h-day 6 after KA injection) and the chronic phase (rats sacrificed beyond day 60 after KA injection). The late relative increase of MPPF binding suggests an epilepsy-induced increase of 5-HT1a receptors in the hippocampus. This effect needs to be further characterized before considering PET determination of hippocampal MPPF binding as a method of post-epileptic neuronal loss assessment.
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Affiliation(s)
- P Van Bogaert
- PET/Biomedical Cyclotron Unit, Hôpital Erasme, Brussels, Belgium.
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