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Luurtsema G, Pichler V, Bongarzone S, Seimbille Y, Elsinga P, Gee A, Vercouillie J. EANM guideline for harmonisation on molar activity or specific activity of radiopharmaceuticals: impact on safety and imaging quality. EJNMMI Radiopharm Chem 2021; 6:34. [PMID: 34628570 PMCID: PMC8502193 DOI: 10.1186/s41181-021-00149-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/20/2021] [Indexed: 02/04/2023] Open
Abstract
This guideline on molar activity (Am) and specific activity (As) focusses on small molecules, peptides and macromolecules radiolabelled for diagnostic and therapeutic applications. In this guideline we describe the definition of Am and As, and how these measurements must be standardised and harmonised. Selected examples highlighting the importance of Am and As in imaging studies of saturable binding sites will be given, and the necessity of using appropriate materials and equipment will be discussed. Furthermore, common Am pitfalls and remedies are described. Finally, some aspects of Am in relation the emergence of a new generation of highly sensitive PET scanners will be discussed.
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Affiliation(s)
- Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
| | - Verena Pichler
- Department of Pharmaceutical Sciences, Medical University of Vienna, Vienna, Austria
| | | | - Yann Seimbille
- Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Philip Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
| | - Antony Gee
- Department of Imaging Sciences, King's College London, London, UK
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Wong YC, Ilkova T, van Wijk RC, Hartman R, de Lange ECM. Development of a population pharmacokinetic model to predict brain distribution and dopamine D2 receptor occupancy of raclopride in non-anesthetized rat. Eur J Pharm Sci 2017; 111:514-525. [PMID: 29106979 DOI: 10.1016/j.ejps.2017.10.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 09/13/2017] [Accepted: 10/22/2017] [Indexed: 12/11/2022]
Abstract
BACKGROUND Raclopride is a selective antagonist of the dopamine D2 receptor. It is one of the most frequently used in vivo D2 tracers (at low doses) for assessing drug-induced receptor occupancy (RO) in animals and humans. It is also commonly used as a pharmacological blocker (at high doses) to occupy the available D2 receptors and antagonize the action of dopamine or drugs on D2 in preclinical studies. The aims of this study were to comprehensively evaluate its pharmacokinetic (PK) profiles in different brain compartments and to establish a PK-RO model that could predict the brain distribution and RO of raclopride in the freely moving rat using a LC-MS based approach. METHODS Rats (n=24) received a 10-min IV infusion of non-radiolabeled raclopride (1.61μmol/kg, i.e. 0.56mg/kg). Plasma and the brain tissues of striatum (with high density of D2 receptors) and cerebellum (with negligible amount of D2 receptors) were collected. Additional microdialysis experiments were performed in some rats (n=7) to measure the free drug concentration in the extracellular fluid of the striatum and cerebellum. Raclopride concentrations in all samples were analyzed by LC-MS. A population PK-RO model was constructed in NONMEM to describe the concentration-time profiles in the unbound plasma, brain extracellular fluid and brain tissue compartments and to estimate the RO based on raclopride-D2 receptor binding kinetics. RESULTS In plasma raclopride showed a rapid distribution phase followed by a slower elimination phase. The striatum tissue concentrations were consistently higher than that of cerebellum tissue throughout the whole experimental period (10-h) due to higher non-specific tissue binding and D2 receptor binding in the striatum. Model-based simulations accurately predicted the literature data on rat plasma PK, brain tissue PK and D2 RO at different time points after intravenous or subcutaneous administration of raclopride at tracer dose (RO <10%), sub-pharmacological dose (RO 10%-30%) and pharmacological dose (RO >30%). CONCLUSION For the first time a predictive model that could describe the quantitative in vivo relationship between dose, PK and D2 RO of raclopride in non-anesthetized rat was established. The PK-RO model could facilitate the selection of optimal dose and dosing time when raclopride is used as tracer or as pharmacological blocker in various rat studies. The LC-MS based approach, which doses and quantifies a non-radiolabeled tracer, could be useful in evaluating the systemic disposition and brain kinetics of tracers.
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Affiliation(s)
- Yin Cheong Wong
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Trayana Ilkova
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Rob C van Wijk
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Robin Hartman
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands
| | - Elizabeth C M de Lange
- Division of Pharmacology, Cluster Systems Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.
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Glorie D, Servaes S, Verhaeghe J, Wyckhuys T, Wyffels L, Vanderveken O, Stroobants S, Staelens S. MicroPET Outperforms Beta-Microprobes in Determining Neuroreceptor Availability under Pharmacological Restriction for Cold Mass Occupancy. Front Neurosci 2017; 11:47. [PMID: 28239334 PMCID: PMC5301012 DOI: 10.3389/fnins.2017.00047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/23/2017] [Indexed: 11/13/2022] Open
Abstract
Both non-invasive micro-positron emission tomography (μPET) and in situ beta-microprobes have the ability to determine radiotracer kinetics and neuroreceptor availability in vivo. Beta-microprobes were proposed as a cost-effective alternative to μPET, but literature revealed conflicting results most likely due to methodological differences and inflicted tissue damage. The current study has three main objectives: (i) evaluate the theoretical advantages of beta-microprobes; (ii) perform μPET imaging to assess the impact of (beta-micro)probe implantation on relative tracer delivery (R1) and receptor occupancy (non-displaceable binding potential, BPND) in the rat brain; and (iii) investigate whether beta-microprobe recordings produce robust results when a pharmacological restriction for cold mass dose (tracer dose condition) is imposed. We performed acquisitions (n = 61) in naive animals, dummy probe implanted animals (outer diameter: 0.75 and 1.00 mm) and beta-microprobe implanted animals (outer diameter: 0.75 mm) using two different radiotracers with high affinity for the striatum: [11C]raclopride (n = 29) and [11C]ABP688 (n = 32). In addition, acquisitions were completed with or without an imposed restriction for cold mass occupancy. We estimated BPND and R1 values using the simplified reference tissue method (SRTM). [11C]raclopride dummy μPET BPND (0.75 mm: −13.01 ± 0.94%; 1.00 mm: −13.89 ± 1.20%) and R1 values (0.75 mm: −29.67 ± 4.94%; 1.00 mm: −39.07 ± 3.17%) significantly decreased at the implant side vs. the contralateral intact side. A similar comparison for [11C]ABP688 dummy μPET, demonstrated significantly (p < 0.05) decreased BPND (−19.09 ± 2.45%) and R1 values (−38.12 ± 6.58%) in the striatum with a 1.00 mm implant, but not with a 0.75 mm implant. Particularly in tracer dose conditions, despite lower impact of partial volume effects, beta-microprobes proved unfit to produce representative results due to tissue destruction associated with probe insertion. We advise to use tracer dose μPET to obtain accurate results concerning receptor availability and tracer delivery, keeping in mind associated partial volume effects for which it is possible to correct.
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Affiliation(s)
- Dorien Glorie
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of Antwerp Antwerp, Belgium
| | - Stijn Servaes
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of Antwerp Antwerp, Belgium
| | - Jeroen Verhaeghe
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of Antwerp Antwerp, Belgium
| | - Tine Wyckhuys
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of Antwerp Antwerp, Belgium
| | - Leonie Wyffels
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of AntwerpAntwerp, Belgium; Nuclear Medicine Department, Antwerp University HospitalAntwerp, Belgium
| | - Olivier Vanderveken
- Translational Neurosciences, Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp University Hospital Antwerp, Belgium
| | - Sigrid Stroobants
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of AntwerpAntwerp, Belgium; Nuclear Medicine Department, Antwerp University HospitalAntwerp, Belgium
| | - Steven Staelens
- Faculty of Medicine and Health Sciences, Molecular Imaging Center Antwerp, University of Antwerp Antwerp, Belgium
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A single-scan protocol for absolute D2/3 receptor quantification with [123I]IBZM SPECT. Neuroimage 2017; 147:461-472. [DOI: 10.1016/j.neuroimage.2016.12.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/24/2016] [Accepted: 12/18/2016] [Indexed: 11/19/2022] Open
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Pottier G, Marie S, Goutal S, Auvity S, Peyronneau MA, Stute S, Boisgard R, Dollé F, Buvat I, Caillé F, Tournier N. Imaging the Impact of the P-Glycoprotein (ABCB1) Function on the Brain Kinetics of Metoclopramide. J Nucl Med 2015; 57:309-14. [PMID: 26585058 DOI: 10.2967/jnumed.115.164350] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 11/02/2015] [Indexed: 12/25/2022] Open
Abstract
UNLABELLED The effects of metoclopramide on the central nervous system (CNS) in patients suggest substantial brain distribution. Previous data suggest that metoclopramide brain kinetics may nonetheless be controlled by ATP-binding cassette (ABC) transporters expressed at the blood-brain barrier. We used (11)C-metoclopramide PET imaging to elucidate the kinetic impact of transporter function on metoclopramide exposure to the brain. METHODS (11)C-metoclopramide transport by P-glycoprotein (P-gp; ABCB1) and the breast cancer resistance protein (BCRP; ABCG2) was tested using uptake assays in cells overexpressing P-gp and BCRP. (11)C-metoclopramide brain kinetics were compared using PET in rats (n = 4-5) in the absence and presence of a pharmacologic dose of metoclopramide (3 mg/kg), with or without P-gp inhibition using intravenous tariquidar (8 mg/kg). The (11)C-metoclopramide brain distribution (VT based on Logan plot analysis) and brain kinetics (2-tissue-compartment model) were characterized with either a measured or an imaged-derived input function. Plasma and brain radiometabolites were studied using radio-high-performance liquid chromatography analysis. RESULTS (11)C-metoclopramide transport was selective for P-gp over BCRP. Pharmacologic dose did not affect baseline (11)C-metoclopramide brain kinetics (VT = 2.28 ± 0.32 and 2.04 ± 0.19 mL⋅cm(-3) using microdose and pharmacologic dose, respectively). Tariquidar significantly enhanced microdose (11)C-metoclopramide VT (7.80 ± 1.43 mL⋅cm(-3)) with a 4.4-fold increase in K1 (influx rate constant) and a 2.3-fold increase in binding potential (k3/k4) in the 2-tissue-compartment model. In the pharmacologic situation, P-gp inhibition significantly increased metoclopramide brain distribution (VT = 6.28 ± 0.48 mL⋅cm(-3)) with a 2.0-fold increase in K1 and a 2.2-fold decrease in k2 (efflux rate), with no significant impact on binding potential. In this situation, only parent (11)C-metoclopramide could be detected in the brains of P-gp-inhibited rats. CONCLUSION (11)C-metoclopramide benefits from favorable pharmacokinetic properties that offer reliable quantification of P-gp function at the blood-brain barrier in a pharmacologic situation. Using metoclopramide as a model of CNS drug, we demonstrated that P-gp function not only reduces influx but also mediates the efflux from the brain back to the blood compartment, with additional impact on brain distribution. This PET-based strategy of P-gp function investigation may provide new insight on the contribution of P-gp to the variability of response to CNS drugs between patients.
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Affiliation(s)
- Géraldine Pottier
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Solène Marie
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Sébastien Goutal
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Sylvain Auvity
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Marie-Anne Peyronneau
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Simon Stute
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Raphaël Boisgard
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Frédéric Dollé
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Irène Buvat
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Fabien Caillé
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Nicolas Tournier
- Inserm/CEA/Université Paris Sud, UMR 1023 - ERL 9218 CNRS, IMIV, Orsay, France; and CEA, DSV, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
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Wimberley CJ, Fischer K, Reilhac A, Pichler BJ, Gregoire MC. A data driven method for estimation of B(avail) and appK(D) using a single injection protocol with [¹¹C]raclopride in the mouse. Neuroimage 2014; 99:365-76. [PMID: 24862069 DOI: 10.1016/j.neuroimage.2014.05.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 04/09/2014] [Accepted: 05/18/2014] [Indexed: 11/19/2022] Open
Abstract
PURPOSE The partial saturation approach (PSA) is a simple, single injection experimental protocol that will estimate both B(avail) and appK(D) without the use of blood sampling. This makes it ideal for use in longitudinal studies of neurodegenerative diseases in the rodent. The aim of this study was to increase the range and applicability of the PSA by developing a data driven strategy for determining reliable regional estimates of receptor density (B(avail)) and in vivo affinity (1/appK(D)), and validate the strategy using a simulation model. METHODS The data driven method uses a time window guided by the dynamic equilibrium state of the system as opposed to using a static time window. To test the method, simulations of partial saturation experiments were generated and validated against experimental data. The experimental conditions simulated included a range of receptor occupancy levels and three different B(avail) and appK(D) values to mimic diseases states. Also the effect of using a reference region and typical PET noise on the stability and accuracy of the estimates was investigated. RESULTS The investigations showed that the parameter estimates in a simulated healthy mouse, using the data driven method were within 10±30% of the simulated input for the range of occupancy levels simulated. Throughout all experimental conditions simulated, the accuracy and robustness of the estimates using the data driven method were much improved upon the typical method of using a static time window, especially at low receptor occupancy levels. Introducing a reference region caused a bias of approximately 10% over the range of occupancy levels. CONCLUSIONS Based on extensive simulated experimental conditions, it was shown the data driven method provides accurate and precise estimates of B(avail) and appK(D) for a broader range of conditions compared to the original method.
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Affiliation(s)
- Catriona J Wimberley
- Brain and Mind Research Institute, University of Sydney, L2, Building F, 94, Australia; ANSTO Life Sciences, Australia.
| | - Kristina Fischer
- Eberhard Karls University of Tuebingen, Department of Preclinical Imaging and Radiopharmacy, Germany
| | | | - Bernd J Pichler
- Eberhard Karls University of Tuebingen, Department of Preclinical Imaging and Radiopharmacy, Germany
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Kuntner C. Kinetic modeling in pre-clinical positron emission tomography. Z Med Phys 2014; 24:274-85. [PMID: 24629308 DOI: 10.1016/j.zemedi.2014.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/11/2014] [Accepted: 02/11/2014] [Indexed: 12/11/2022]
Abstract
Pre-clinical positron emission tomography (PET) has evolved in the last few years from pure visualization of radiotracer uptake and distribution towards quantification of the physiological parameters. For reliable and reproducible quantification the kinetic modeling methods used to obtain relevant parameters of radiotracer tissue interaction are important. Here we present different kinetic modeling techniques with a focus on compartmental models including plasma input models and reference tissue input models. The experimental challenges off deriving the plasma input function in rodents and the effect of anesthesia are discussed. Finally, in vivo application of kinetic modeling in various areas of pre-clinical research is presented and compared to human data.
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Affiliation(s)
- Claudia Kuntner
- Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria.
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Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
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Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
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Wooten DW, Hillmer AT, Moirano JM, Ahlers EO, Slesarev M, Barnhart TE, Mukherjee J, Schneider ML, Christian BT. Measurement of 5-HT(1A) receptor density and in-vivo binding parameters of [(18)F]mefway in the nonhuman primate. J Cereb Blood Flow Metab 2012; 32:1546-58. [PMID: 22472611 PMCID: PMC3421091 DOI: 10.1038/jcbfm.2012.43] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The goal of this work was to characterize the in-vivo behavior of [(18)F]mefway as a suitable positron emission tomography (PET) radiotracer for the assay of 5-hydroxytryptamine(1A) (5-HT(1A)) receptor density (B(max)). Six rhesus monkeys were studied using a multiple-injection (M-I) protocol consisting of three sequential bolus injections of [(18)F]mefway. Injection times and amounts of unlabeled mefway were optimized for the precise measurement of B(max) and specific binding parameters k(off) and k(on) for estimation of apparent K(D). The PET time series were acquired for 180 minutes with arterial sampling performed throughout. Compartmental analysis using the arterial input function was performed to obtain estimates for K(1), k(2), k(off), B(max), and K(Dapp) in the cerebral cortex and raphe nuclei (RN) using a model that accounted for nontracer doses of mefway. Averaged over subjects, highest binding was seen in the mesial temporal and dorsal anterior cingulate cortices with B(max) values of 42±8 and 36±8 pmol/mL, respectively, and lower values in the superior temporal cortex, RN, and parietal cortex of 24±4, 19±4, and 13±2 pmol/mL, respectively. The K(Dapp) of mefway for the 5-HT(1A) receptor sites was 4.3±1.3 nmol/L. In conclusion, these results show that M-I [(18)F]mefway PET experiments can be used for the in-vivo measurement of 5-HT(1A) receptor density.
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Affiliation(s)
- Dustin W Wooten
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.
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Fischer K, Sossi V, Schmid A, Thunemann M, Maier FC, Judenhofer MS, Mannheim JG, Reischl G, Pichler BJ. Noninvasive Nuclear Imaging Enables the In Vivo Quantification of Striatal Dopamine Receptor Expression and Raclopride Affinity in Mice. J Nucl Med 2011; 52:1133-41. [DOI: 10.2967/jnumed.110.086942] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Positron emission tomography imaging demonstrates correlation between behavioral recovery and correction of dopamine neurotransmission after gene therapy. J Neurosci 2009; 29:1544-53. [PMID: 19193901 DOI: 10.1523/jneurosci.4491-08.2009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In vivo gene transfer using viral vectors is an emerging therapy for neurodegenerative diseases with a clinical impact recently demonstrated in Parkinson's disease patients. Recombinant adeno-associated viral (rAAV) vectors, in particular, provide an excellent tool for long-term expression of therapeutic genes in the brain. Here we used the [(11)C]raclopride [(S)-(-)-3,5-dichloro-N-((1-ethyl-2-pyrrolidinyl)methyl)-2-hydroxy-6-methoxybenzamide] micro-positron emission tomography (PET) technique to demonstrate that delivery of the tyrosine hydroxylase (TH) and GTP cyclohydrolase 1 (GCH1) enzymes using an rAAV5 vector normalizes the increased [(11)C]raclopride binding in hemiparkinsonian rats. Importantly, we show in vivo by microPET imaging and postmortem by classical binding assays performed in the very same animals that the changes in [(11)C]raclopride after viral vector-based enzyme replacement therapy is attributable to a decrease in the affinity of the tracer binding to the D(2) receptors, providing evidence for reconstitution of a functional pool of endogenous dopamine in the striatum. Moreover, the extent of the normalization in this non-invasive imaging measure was highly correlated with the functional recovery in motor behavior. The PET imaging protocol used in this study is fully adaptable to humans and thus can serve as an in vivo imaging technique to follow TH + GCH1 gene therapy in PD patients and provide an additional objective measure to a potential clinical trial using rAAV vectors to deliver l-3,4-dihydroxyphenylanaline in the brain.
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Pain F, Dhenain M, Gurden H, Routier AL, Lefebvre F, Mastrippolito R, Lanièce P. A method based on Monte Carlo simulations and voxelized anatomical atlases to evaluate and correct uncertainties on radiotracer accumulation quantitation in beta microprobe studies in the rat brain. Phys Med Biol 2008; 53:5385-404. [DOI: 10.1088/0031-9155/53/19/008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Metabotropic glutamate receptor modulation, translational methods, and biomarkers: relationships with anxiety. Psychopharmacology (Berl) 2008; 199:389-402. [PMID: 18322676 DOI: 10.1007/s00213-008-1096-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 01/28/2008] [Indexed: 01/31/2023]
Abstract
RATIONALE The increasing awareness of the need to align clinical and preclinical research to facilitate rapid development of new drug therapies is reflected in the recent introduction of the term "translational medicine". This review examines the implications of translational medicine for psychiatric disorders, focusing on metabotropic glutamate (mGlu) receptor biology in anxiety disorders and on anxiety-related biomarkers. OBJECTIVES This review aims to (1) examine recent progress in translational medicine, emphasizing the role that translational research has played in understanding of the potential of mGlu receptor agonists and antagonists as anxiolytics, (2) identify lacunas where animal and human research have yet to be connected, and (3) suggest areas where translational research can be further developed. RESULTS Current data show that animal and human mGlu(5) binding can be directly compared in experiments using the PET ligand (11)C-ABP688. Testing of the mGlu(2/3) receptor agonist LY354740 in the fear-potentiated startle paradigm allows direct functional comparisons between animals and humans. LY354740 has been tested in panic models, but in different models in rats and humans, hindering efforts at translation. Other potentially translatable methods, such as stress-induced hyperthermia and HPA-axis measures, either have been underexploited or are associated with technical difficulties. New techniques such as quantitative trait loci (QTL) analysis may be useful for generating novel biomarkers of anxiety. CONCLUSIONS Translational medicine approaches can be valuable to the development of anxiolytics, but the amount of cross-fertilization between clinical and pre-clinical departments will need to be expanded to realize the full potential of these approaches.
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Galineau L, Wilson AA, Garcia A, Houle S, Kapur S, Ginovart N. In vivo characterization of the pharmacokinetics and pharmacological properties of [11C]-(+)-PHNO in rats using an intracerebral beta-sensitive system. Synapse 2006; 60:172-83. [PMID: 16715499 DOI: 10.1002/syn.20290] [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] [Indexed: 11/11/2022]
Abstract
This study reports on the binding kinetics and pharmacological characterization of [11C]-(+)-PHNO ((+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol), a promising agonist radiotracer for in vivo evaluation of the D2-receptor. Its in vivo kinetics were monitored in rat striatum and cerebellum using a beta-sensitive Microprobe system. Control studies showed that [11C]-(+)-PHNO binding was reversible and reached a peak time equilibrium of specific binding in striatum 30 min after radiotracer injection. The binding potential (BP) calculated by the simplified reference tissue model was 3-fold higher than that measured with [11C]-(-)-NPA (2.14 +/- 0.50 vs. 0.66 +/- 0.01, respectively). In contrast, the methyl analog of (+)-PHNO, [11C]-(+)-MHNO, which displayed promising D2-agonist properties in vitro, showed no specific binding in the striatum in vivo. [11C]-(+)-PHNO binding was totally blocked by raclopride (1 mg/kg; i.v.) and 97% displaced by NPA (2 mg/kg; i.v.) suggesting that [11C]-(+)-PHNO was specific for the high affinity states of D2/D3-receptors. However, (+)-PHNO (1 mg/kg; i.v.) totally blocked and displaced [11C]-raclopride binding in striatum. Thus, (+)-PHNO at high concentrations might be able to bind to the low affinity states of D2/D3-receptors. After an amphetamine pretreatment (2 mg/kg; i.v.), a 69% decrease in BP value (P < 0.05) was observed for [11C]-(+)-PHNO indicating that its binding was highly sensitive to variations of endogenous DA. These results substantiate the use of [11C]-(+)-PHNO as an agonist radiotracer for D2-imaging. The sensitivity of its binding to competition with endogenous DA suggests an association with the subset of high affinity state D2-receptors.
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Affiliation(s)
- Laurent Galineau
- The Vivian Rakoff Positron Emission Tomography Unit, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
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