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Mori A, Chen JF, Uchida S, Durlach C, King SM, Jenner P. The Pharmacological Potential of Adenosine A 2A Receptor Antagonists for Treating Parkinson's Disease. Molecules 2022; 27:2366. [PMID: 35408767 PMCID: PMC9000505 DOI: 10.3390/molecules27072366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 02/07/2023] Open
Abstract
The adenosine A2A receptor subtype is recognized as a non-dopaminergic pharmacological target for the treatment of neurodegenerative disorders, notably Parkinson's disease (PD). The selective A2A receptor antagonist istradefylline is approved in the US and Japan as an adjunctive treatment to levodopa/decarboxylase inhibitors in adults with PD experiencing OFF episodes or a wearing-off phenomenon; however, the full potential of this drug class remains to be explored. In this article, we review the pharmacology of adenosine A2A receptor antagonists from the perspective of the treatment of both motor and non-motor symptoms of PD and their potential for disease modification.
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Affiliation(s)
- Akihisa Mori
- Kyowa Kirin Co., Ltd., Tokyo 100-0004, Japan; (A.M.); (S.U.)
| | - Jiang-Fan Chen
- Molecular Neuropharmacology Laboratory, Wenzhou Medical University, Wenzhou 325015, China;
| | - Shinichi Uchida
- Kyowa Kirin Co., Ltd., Tokyo 100-0004, Japan; (A.M.); (S.U.)
| | | | | | - Peter Jenner
- Institute of Pharmaceutical Science, Kings College London, London SE1 9NH, UK
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2
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Lai TH, Schröder S, Toussaint M, Dukić-Stefanović S, Kranz M, Ludwig FA, Fischer S, Steinbach J, Deuther-Conrad W, Brust P, Moldovan RP. Development of 18F-Labeled Radiotracers for PET Imaging of the Adenosine A 2A Receptor: Synthesis, Radiolabeling and Preliminary Biological Evaluation. Int J Mol Sci 2021; 22:ijms22052285. [PMID: 33669003 PMCID: PMC7956753 DOI: 10.3390/ijms22052285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/21/2021] [Accepted: 02/22/2021] [Indexed: 12/19/2022] Open
Abstract
The adenosine A2A receptor (A2AR) represents a potential therapeutic target for neurodegenerative diseases. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor changes of receptor density and/or occupancy during the A2AR-tailored therapy, we designed a library of fluorinated analogs based on a recently published lead compound (PPY). Among those, the highly affine 4-fluorobenzyl derivate (PPY1; Ki(hA2AR) = 5.3 nM) and the 2-fluorobenzyl derivate (PPY2; Ki(hA2AR) = 2.1 nM) were chosen for 18F-labeling via an alcohol-enhanced copper-mediated procedure starting from the corresponding boronic acid pinacol ester precursors. Investigations of the metabolic stability of [18F]PPY1 and [18F]PPY2 in CD-1 mice by radio-HPLC analysis revealed parent fractions of more than 76% of total activity in the brain. Specific binding of [18F]PPY2 on mice brain slices was demonstrated by in vitro autoradiography. In vivo PET/magnetic resonance imaging (MRI) studies in CD-1 mice revealed a reasonable high initial brain uptake for both radiotracers, followed by a fast clearance.
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Affiliation(s)
- Thu Hang Lai
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
- Correspondence: (T.H.L.); (R.-P.M.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4634 (R.-P.M.)
| | - Susann Schröder
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Sladjana Dukić-Stefanović
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- PET Imaging Center, University Hospital of North Norway (UNN), 9009 Tromsø, Norway
- Nuclear Medicine and Radiation Biology Research Group, The Arctic University of Norway, 9009 Tromsø, Norway
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Correspondence: (T.H.L.); (R.-P.M.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4634 (R.-P.M.)
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Prasad K, de Vries EFJ, Elsinga PH, Dierckx RAJO, van Waarde A. Allosteric Interactions between Adenosine A 2A and Dopamine D 2 Receptors in Heteromeric Complexes: Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging. Int J Mol Sci 2021; 22:ijms22041719. [PMID: 33572077 PMCID: PMC7915359 DOI: 10.3390/ijms22041719] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A2A and dopamine D2 receptors (R). Stimulation of A2AR inhibits and blockade of A2AR enhances D2R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D2R via its interaction with A2AR. Reciprocal A2AR/D2R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A2AR and D2R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A2AR/D2R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A2AR/D2R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review.
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Affiliation(s)
- Kavya Prasad
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
| | - Erik F. J. de Vries
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Department of Diagnostic Sciences, Ghent University Faculty of Medicine and Health Sciences, C.Heymanslaan 10, 9000 Gent, Belgium
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
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Goud NS, Bhattacharya A, Joshi RK, Nagaraj C, Bharath RD, Kumar P. Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology. J Med Chem 2021; 64:1223-1259. [PMID: 33499603 DOI: 10.1021/acs.jmedchem.0c01053] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Ahana Bhattacharya
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Raman Kumar Joshi
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
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D'Elia A, Schiavi S, Soluri A, Massari R, Soluri A, Trezza V. Role of Nuclear Imaging to Understand the Neural Substrates of Brain Disorders in Laboratory Animals: Current Status and Future Prospects. Front Behav Neurosci 2020; 14:596509. [PMID: 33362486 PMCID: PMC7759612 DOI: 10.3389/fnbeh.2020.596509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular imaging, which allows the real-time visualization, characterization and measurement of biological processes, is becoming increasingly used in neuroscience research. Scintigraphy techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) provide qualitative and quantitative measurement of brain activity in both physiological and pathological states. Laboratory animals, and rodents in particular, are essential in neuroscience research, providing plenty of models of brain disorders. The development of innovative high-resolution small animal imaging systems together with their radiotracers pave the way to the study of brain functioning and neurotransmitter release during behavioral tasks in rodents. The assessment of local changes in the release of neurotransmitters associated with the performance of a given behavioral task is a turning point for the development of new potential drugs for psychiatric and neurological disorders. This review addresses the role of SPECT and PET small animal imaging systems for a better understanding of brain functioning in health and disease states. Brain imaging in rodent models faces a series of challenges since it acts within the boundaries of current imaging in terms of sensitivity and spatial resolution. Several topics are discussed, including technical considerations regarding the strengths and weaknesses of both technologies. Moreover, the application of some of the radioligands developed for small animal nuclear imaging studies is discussed. Then, we examine the changes in metabolic and neurotransmitter activity in various brain areas during task-induced neural activation with special regard to the imaging of opioid, dopaminergic and cannabinoid receptors. Finally, we discuss the current status providing future perspectives on the most innovative imaging techniques in small laboratory animals. The challenges and solutions discussed here might be useful to better understand brain functioning allowing the translation of preclinical results into clinical applications.
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Affiliation(s)
- Annunziata D'Elia
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy.,Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Sara Schiavi
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Andrea Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Roberto Massari
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Alessandro Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Viviana Trezza
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
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Cybulska K, Perk L, Booij J, Laverman P, Rijpkema M. Huntington's Disease: A Review of the Known PET Imaging Biomarkers and Targeting Radiotracers. Molecules 2020; 25:molecules25030482. [PMID: 31979301 PMCID: PMC7038198 DOI: 10.3390/molecules25030482] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 12/19/2022] Open
Abstract
Huntington’s disease (HD) is a fatal neurodegenerative disease caused by a CAG expansion mutation in the huntingtin gene. As a result, intranuclear inclusions of mutant huntingtin protein are formed, which damage striatal medium spiny neurons (MSNs). A review of Positron Emission Tomography (PET) studies relating to HD was performed, including clinical and preclinical data. PET is a powerful tool for visualisation of the HD pathology by non-invasive imaging of specific radiopharmaceuticals, which provide a detailed molecular snapshot of complex mechanistic pathways within the brain. Nowadays, radiochemists are equipped with an impressive arsenal of radioligands to accurately recognise particular receptors of interest. These include key biomarkers of HD: adenosine, cannabinoid, dopaminergic and glutamateric receptors, microglial activation, phosphodiesterase 10 A and synaptic vesicle proteins. This review aims to provide a radiochemical picture of the recent developments in the field of HD PET, with significant attention devoted to radiosynthetic routes towards the tracers relevant to this disease.
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Affiliation(s)
- Klaudia Cybulska
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
- Radboud Translational Medicine B.V., Radboud University Medical Center, Geert Grooteplein 21 (route 142), 6525 EZ Nijmegen, The Netherlands;
- Correspondence:
| | - Lars Perk
- Radboud Translational Medicine B.V., Radboud University Medical Center, Geert Grooteplein 21 (route 142), 6525 EZ Nijmegen, The Netherlands;
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Peter Laverman
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
| | - Mark Rijpkema
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein-Zuid 10, 6525 EZ Nijmegen, The Netherlands; (J.B.); (P.L.); (M.R.)
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Tracers for non-invasive radionuclide imaging of immune checkpoint expression in cancer. EJNMMI Radiopharm Chem 2019; 4:29. [PMID: 31696402 PMCID: PMC6834817 DOI: 10.1186/s41181-019-0078-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/21/2019] [Indexed: 12/11/2022] Open
Abstract
Abstract Immunotherapy with checkpoint inhibitors demonstrates impressive improvements in the treatment of several types of cancer. Unfortunately, not all patients respond to therapy while severe immune-related adverse effects are prevalent. Currently, patient stratification is based on immunotherapy marker expression through immunohistochemical analysis on biopsied material. However, expression can be heterogeneous within and between tumor lesions, amplifying the sampling limitations of biopsies. Analysis of immunotherapy target expression by non-invasive quantitative molecular imaging with PET or SPECT may overcome this issue. In this review, an overview of tracers that have been developed for preclinical and clinical imaging of key immunotherapy targets, such as programmed cell death-1, programmed cell death ligand-1, IDO1 and cytotoxic T lymphocyte-associated antigen-4 is presented. We discuss important aspects to consider when developing such tracers and outline the future perspectives of molecular imaging of immunotherapy markers. Graphical abstract Current techniques in immune checkpoint imaging and its potential for future applications ![]()
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Blum D, Chern Y, Domenici MR, Buée L, Lin CY, Rea W, Ferré S, Popoli P. The Role of Adenosine Tone and Adenosine Receptors in Huntington's Disease. J Caffeine Adenosine Res 2018; 8:43-58. [PMID: 30023989 PMCID: PMC6049521 DOI: 10.1089/caff.2018.0006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by a mutation in the IT15 gene that encodes for the huntingtin protein. Mutated hungtingtin, although widely expressed in the brain, predominantly affects striato-pallidal neurons, particularly enriched with adenosine A2A receptors (A2AR), suggesting a possible involvement of adenosine and A2AR is the pathogenesis of HD. In fact, polymorphic variation in the ADORA2A gene influences the age at onset in HD, and A2AR dynamics is altered by mutated huntingtin. Basal levels of adenosine and adenosine receptors are involved in many processes critical for neuronal function and homeostasis, including modulation of synaptic activity and excitotoxicity, the control of neurotrophin levels and functions, and the regulation of protein degradation mechanisms. In the present review, we critically analyze the current literature involving the effect of altered adenosine tone and adenosine receptors in HD and discuss why therapeutics that modulate the adenosine system may represent a novel approach for the treatment of HD.
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Affiliation(s)
- David Blum
- University of Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, LabEx DISTALZ, Lille, France
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Maria Rosaria Domenici
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
| | - Luc Buée
- University of Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, LabEx DISTALZ, Lille, France
| | - Chien-Yu Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - William Rea
- Integrative Neurobiology Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland
| | - Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland
| | - Patrizia Popoli
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
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Oliveira-Giacomelli Á, Naaldijk Y, Sardá-Arroyo L, Gonçalves MCB, Corrêa-Velloso J, Pillat MM, de Souza HDN, Ulrich H. Purinergic Receptors in Neurological Diseases With Motor Symptoms: Targets for Therapy. Front Pharmacol 2018; 9:325. [PMID: 29692728 PMCID: PMC5902708 DOI: 10.3389/fphar.2018.00325] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 03/21/2018] [Indexed: 12/13/2022] Open
Abstract
Since proving adenosine triphosphate (ATP) functions as a neurotransmitter in neuron/glia interactions, the purinergic system has been more intensely studied within the scope of the central nervous system. In neurological disorders with associated motor symptoms, including Parkinson's disease (PD), motor neuron diseases (MND), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's Disease (HD), restless leg syndrome (RLS), and ataxias, alterations in purinergic receptor expression and activity have been noted, indicating a potential role for this system in disease etiology and progression. In neurodegenerative conditions, neural cell death provokes extensive ATP release and alters calcium signaling through purinergic receptor modulation. Consequently, neuroinflammatory responses, excitotoxicity and apoptosis are directly or indirectly induced. This review analyzes currently available data, which suggests involvement of the purinergic system in neuro-associated motor dysfunctions and underlying mechanisms. Possible targets for pharmacological interventions are also discussed.
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Affiliation(s)
| | - Yahaira Naaldijk
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Laura Sardá-Arroyo
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Maria C. B. Gonçalves
- Department of Neurology and Neuroscience, Medical School, Federal University of São Paulo, São Paulo, Brazil
| | - Juliana Corrêa-Velloso
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Micheli M. Pillat
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Héllio D. N. de Souza
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
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10
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Mishina M, Kimura Y, Sakata M, Ishii K, Oda K, Toyohara J, Kimura K, Ishiwata K. Age-Related Decrease in Male Extra-Striatal Adenosine A 1 Receptors Measured Using11C-MPDX PET. Front Pharmacol 2017; 8:903. [PMID: 29326588 PMCID: PMC5741655 DOI: 10.3389/fphar.2017.00903] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/28/2017] [Indexed: 11/15/2022] Open
Abstract
Adenosine A1 receptors (A1Rs) are widely distributed throughout the entire human brain, while adenosine A2A receptors (A2ARs) are present in dopamine-rich areas of the brain, such as the basal ganglia. A past study using autoradiography reported a reduced binding ability of A1R in the striatum of old rats. We developed positron emission tomography (PET) ligands for mapping the adenosine receptors and we successfully visualized the A1Rs using 8-dicyclopropylmethyl-1-11C-methyl-3-propylxanthine (11C-MPDX). We previously reported that the density of A1Rs decreased with age in the human striatum, although we could not observe an age-related change in A2ARs. The aim of this study was to investigate the age-related change of the density of A1Rs in the thalamus and cerebral cortices of healthy participants using 11C-MPDX PET. We recruited eight young (22.0 ± 1.7 years) and nine elderly healthy male volunteers (65.7 ± 8.0 years). A dynamic series of decay-corrected PET scans was performed for 60 min starting with the injection of 11C-MPDX. We placed the circular regions of interest of 10 mm in diameter in 11C-MPDX PET images. The values for the binding potential (BPND) of 11C-MPDX in the thalamus, and frontal, temporal, occipital, and parietal cortices were calculated using a graphical analysis, wherein the reference region was the cerebellum. BPND of 11C-MPDX was significantly lower in elderly participants than young participants in the thalamus, and frontal, temporal, occipital, and parietal cortices. In the human brain, we could observe the age-related decrease in the distribution of A1Rs.
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Affiliation(s)
- Masahiro Mishina
- Department of Neuro-pathophysiological Imaging, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan.,Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Department of Neurological Science, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Yuichi Kimura
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Department of Computational Systems Biology, Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Japan
| | - Muneyuki Sakata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Kenji Ishii
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Keiichi Oda
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Department of Radiological Technology, Faculty of Health Sciences, Hokkaido University of Science, Sapporo, Japan
| | - Jun Toyohara
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Kazumi Kimura
- Department of Neurological Science, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Kiichi Ishiwata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Institute of Cyclotron and Drug Discovery Research, Southern TOHOKU Research Institute for Neuroscience, Koriyama, Japan.,Department of Biofunctional Imaging, Fukushima Medical University, Fukushima, Japan
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11
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In Vivo PET Imaging of Adenosine 2A Receptors in Neuroinflammatory and Neurodegenerative Disease. CONTRAST MEDIA & MOLECULAR IMAGING 2017; 2017:6975841. [PMID: 29348737 PMCID: PMC5733838 DOI: 10.1155/2017/6975841] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/18/2017] [Indexed: 01/01/2023]
Abstract
Adenosine receptors are G-protein coupled P1 purinergic receptors that are broadly expressed in the peripheral immune system, vasculature, and the central nervous system (CNS). Within the immune system, adenosine 2A (A2A) receptor-mediated signaling exerts a suppressive effect on ongoing inflammation. In healthy CNS, A2A receptors are expressed mainly within the neurons of the basal ganglia. Alterations in A2A receptor function and expression have been noted in movement disorders, and in Parkinson's disease pharmacological A2A receptor antagonism leads to diminished motor symptoms. Although A2A receptors are expressed only at a low level in the healthy CNS outside striatum, pathological challenge or inflammation has been shown to lead to upregulation of A2A receptors in extrastriatal CNS tissue, and this has been successfully quantitated using in vivo positron emission tomography (PET) imaging and A2A receptor-binding radioligands. Several radioligands for PET imaging of A2A receptors have been developed in recent years, and A2A receptor-targeting PET imaging may thus provide a potential additional tool to evaluate various aspects of neuroinflammation in vivo. This review article provides a brief overview of A2A receptors in healthy brain and in a selection of most important neurological diseases and describes the recent advances in A2A receptor-targeting PET imaging studies.
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12
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Tartaglione AM, Popoli P, Calamandrei G. Regenerative medicine in Huntington's disease: Strengths and weaknesses of preclinical studies. Neurosci Biobehav Rev 2017; 77:32-47. [PMID: 28223129 DOI: 10.1016/j.neubiorev.2017.02.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/26/2017] [Accepted: 02/17/2017] [Indexed: 01/22/2023]
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder, characterized by impairment in motor, cognitive and psychiatric domains. Currently, there is no specific therapy to act on the onset or progression of HD. The marked neuronal death observed in HD is a main argument in favour of stem cells (SCs) transplantation as a promising therapeutic perspective to replace the population of lost neurons and restore the functionality of the damaged circuitry. The availability of rodent models of HD encourages the investigation of the restorative potential of SCs transplantation longitudinally. However, the results of preclinical studies on SCs therapy in HD are so far largely inconsistent; this hampers the individuation of the more appropriate model and precludes the comparative analysis of transplant efficacy on behavioural end points. Thus, this review will describe the state of the art of in vivo research on SCs therapy in HD, analysing in a translational perspective the strengths and weaknesses of animal studies investigating the therapeutic potential of cell transplantation on HD progression.
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Affiliation(s)
- A M Tartaglione
- Centre for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - P Popoli
- National Centre for Medicines Research and Preclinical/Clinical Evaluation, Rome, Italy
| | - G Calamandrei
- Centre for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy.
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13
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Zhou X, Khanapur S, de Jong JR, Willemsen AT, Dierckx RA, Elsinga PH, de Vries EF. In vivo evaluation of [ 11C]preladenant positron emission tomography for quantification of adenosine A 2A receptors in the rat brain. J Cereb Blood Flow Metab 2017; 37:577-589. [PMID: 26917190 PMCID: PMC5381452 DOI: 10.1177/0271678x16634714] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
[11C]Preladenant was developed as a novel adenosine A2A receptor positron emission tomography radioligand. The present study aims to evaluate the suitability of [11C]preladenant positron emission tomography for the quantification of striatal A2A receptor density and the assessment of striatal A2A receptor occupancy by KW-6002. Sixty- or ninety-minute dynamic positron emission tomography imaging was performed on rats. Tracer kinetics was quantified by the two-tissue compartment model, Logan graphical analysis and several reference tissue-based models. Test-retest reproducibility was assessed by repeated imaging on two consecutive days. Two-tissue compartment model and Logan plot estimated comparable distribution volume ( VT) values of ∼10 in the A2A receptor-rich striatum and substantially lower values in all extra-striatal regions (∼1.5-2.5). The simplified reference tissue model with midbrain or occipital cortex as the reference region proved to be the best non-invasive model for quantification of A2A receptor, showing a striatal binding potential ( BPND) value of ∼5.5, and a test-retest variability of ∼5.5%. The brain metabolite analysis showed that at 60-min post injection, 17% of the radioactivity in the brain was due to radioactive metabolites. The ED50 of KW-6002 in rat striatum for i.p. injection was 0.044-0.062 mg/kg. The study demonstrates that [11C]preladenant is a suitable tracer to quantify striatal A2A receptor density and assess A2A receptor occupancy by A2A receptor-targeting molecules.
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Affiliation(s)
- Xiaoyun Zhou
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Shivashankar Khanapur
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Johan R de Jong
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Antoon Tm Willemsen
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Rudi Ajo Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Erik Fj de Vries
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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14
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van Waarde A, Dierckx RAJO, Zhou X, Khanapur S, Tsukada H, Ishiwata K, Luurtsema G, de Vries EFJ, Elsinga PH. Potential Therapeutic Applications of Adenosine A 2A Receptor Ligands and Opportunities for A 2A Receptor Imaging. Med Res Rev 2017; 38:5-56. [PMID: 28128443 DOI: 10.1002/med.21432] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/31/2016] [Accepted: 11/14/2016] [Indexed: 12/13/2022]
Abstract
Adenosine A2A receptors (A2A Rs) are highly expressed in the human striatum, and at lower densities in the cerebral cortex, the hippocampus, and cells of the immune system. Antagonists of these receptors are potentially useful for the treatment of motor fluctuations, epilepsy, postischemic brain damage, or cognitive impairment, and for the control of an immune checkpoint during immunotherapy of cancer. A2A R agonists may suppress transplant rejection and graft-versus-host disease; be used to treat inflammatory disorders such as asthma, inflammatory bowel disease, and rheumatoid arthritis; be locally applied to promote wound healing and be employed in a strategy for transient opening of the blood-brain barrier (BBB) so that therapeutic drugs and monoclonal antibodies can enter the brain. Increasing A2A R signaling in adipose tissue is also a potential strategy to combat obesity. Several radioligands for positron emission tomography (PET) imaging of A2A Rs have been developed in recent years. This review article presents a critical overview of the potential therapeutic applications of A2A R ligands, the use of A2A R imaging in drug development, and opportunities and limitations of PET imaging in future research.
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Affiliation(s)
- Aren van Waarde
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
| | - Rudi A J O Dierckx
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands.,Department of Nuclear Medicine, University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium
| | - Xiaoyun Zhou
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
| | - Shivashankar Khanapur
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
| | - Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
| | - Kiichi Ishiwata
- Research Institute of Cyclotron and Drug Discovery Research, Southern TOHOKU Research Institute for Neuroscience, 7-115 Yatsuyamada, Koriyama, 963-8052, Japan.,Department of Biofunctional Imaging, Fukushima Medical University, 1 Hikarigaoka, Fukushima, 960-1295, Japan.,Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Gert Luurtsema
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
| | - Erik F J de Vries
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
| | - Philip H Elsinga
- University of Groningen, University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, 1, 9713 GZ, Groningen, The Netherlands
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15
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Lee CF, Chern Y. Adenosine receptors and Huntington's disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 119:195-232. [PMID: 25175968 DOI: 10.1016/b978-0-12-801022-8.00010-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Adenosine regulates important pathophysiological functions via four distinct adenosine receptor subtypes (A1, A2A, A2B, and A3). The A1 and A2A adenosine receptors (A1R and A2AR) are major targets of caffeine and have been extensively investigated. Huntington's disease (HD) is a dominant neurodegenerative disease caused by an abnormal CAG expansion in the Huntingtin gene. Since the first genetic HD model was created almost two decades ago, tremendous progress regarding the function of the adenosine receptors in HD has been made. Chronic intake of caffeine was recently shown to be positively associated with the disease onset of HD. Moreover, genetic polymorphism of A2AR is believed to impact the age of onset. Given the importance of adenosine receptors as drug targets for human diseases, this review highlights the recent findings that delineate the roles of adenosine receptors in HD and discusses their potential for serving as drug targets and/or biomarkers for HD. Adenosine is a purine nucleoside that regulates important physiological functions via four different adenosine receptors (A1, A2A, A2B, and A3). These adenosine receptors have seven transmembrane domains and belong to the G protein-coupled receptor family. The functions of the A1 adenosine receptor (A1R) and A2A adenosine receptor (A2AR) have been investigated relative to HD. In this review, we summarize the recent findings regarding the role of adenosine receptors in HD and discuss the potential application of adenosine receptors as drug targets and biomarkers for HD.
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Affiliation(s)
- Chien-fei Lee
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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16
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Villar-Menéndez I, Blanch M, Tyebji S, Pereira-Veiga T, Albasanz JL, Martín M, Ferrer I, Pérez-Navarro E, Barrachina M. Increased 5-Methylcytosine and Decreased 5-Hydroxymethylcytosine Levels are Associated with Reduced Striatal A2AR Levels in Huntington’s Disease. Neuromolecular Med 2013; 15:295-309. [DOI: 10.1007/s12017-013-8219-0] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 01/24/2013] [Indexed: 12/22/2022]
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17
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Mishina M, Kimura Y, Naganawa M, Ishii K, Oda K, Sakata M, Toyohara J, Kobayashi S, Katayama Y, Ishiwata K. Differential effects of age on human striatal adenosine A₁ and A(2A) receptors. Synapse 2012; 66:832-9. [PMID: 22623181 DOI: 10.1002/syn.21573] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/01/2012] [Accepted: 05/14/2012] [Indexed: 01/19/2023]
Abstract
The aim of this study was to investigate the effect of age on the distribution of adenosine A₁ receptors (A₁Rs) and adenosine A(2A) receptors (A(2A)Rs) in the striatum of healthy subjects using PET imaging with 8-dicyclopropylmethyl-1-[¹¹C]methyl-3-propylxanthine ([¹¹C]MPDX) and [7-methyl-¹¹C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([¹¹C]TMSX), respectively. We recruited 8 young (22.0 ± 1.7 years) and 10 elderly (65.4 ± 7.6 years) volunteers to undergo [¹¹C]MPDX PET scanning, and 11 young (22.7 ± 2.7 years) and six elderly (60.7 ± 8.5 years) volunteers to undergo [¹¹C]TMSX PET scanning. A dynamic series of decay-corrected PET scans was performed for 60 min following injection of [¹¹C]MPDX or [¹¹C]TMSX. We calculated the binding potential (BP(ND) ) of [¹¹C]MPDX and distribution volume ratio (DVR) of [¹¹C]TMSX in the striatum. The BP(ND) of [¹¹C]MPDX was significantly lower in elderly than in young subjects, both in the putamen and head of the caudate nucleus. The BP(ND) was negatively correlated with age in both the putamen and the head of the caudate nucleus. However, no difference was found between the DVR of [¹¹C]TMSX in the striata of young and elderly subjects, nor was there a correlation between age and the DVR of [¹¹C]TMSX. The effect of age on the distribution of A₁Rs in the human striatum described herein is similar to previous reports of age-related decreases in dopamine D₁ and D₂ receptors. Unlike A₁Rs, however, this study suggests that the distribution of A(2A) Rs does not change with age.
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Affiliation(s)
- Masahiro Mishina
- The Second Department of Internal Medicine, Nippon Medical School, Bunkyo-Ku, Tokyo, Japan; Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Itabashi-Ku, Tokyo, Japan.
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18
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Virdee K, Cumming P, Caprioli D, Jupp B, Rominger A, Aigbirhio FI, Fryer TD, Riss PJ, Dalley JW. Applications of positron emission tomography in animal models of neurological and neuropsychiatric disorders. Neurosci Biobehav Rev 2012; 36:1188-216. [PMID: 22342372 DOI: 10.1016/j.neubiorev.2012.01.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/26/2012] [Accepted: 01/31/2012] [Indexed: 01/08/2023]
Abstract
Positron emission tomography (PET) provides dynamic images of the biodistribution of radioactive tracers in the brain. Through application of the principles of compartmental analysis, tracer uptake can be quantified in terms of specific physiological processes such as cerebral blood flow, cerebral metabolic rate, and the availability of receptors in brain. Whereas early PET studies in animal models of brain diseases were hampered by the limited spatial resolution of PET instruments, dedicated small-animal instruments now provide molecular images of rodent brain with resolution approaching 1mm, the theoretic limit of the method. Major applications of PET for brain research have consisted of studies of animal models of neurological disorders, notably Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington's disease (HD), stroke, epilepsy and traumatic brain injury; these studies have particularly benefited from selective neurochemical lesion models (PD), and also transgenic rodent models (AD, HD). Due to their complex and uncertain pathophysiologies, corresponding models of neuropsychiatric disorders have proven more difficult to establish. Historically, there has been an emphasis on PET studies of dopamine transmission, as assessed with a range of tracers targeting dopamine synthesis, plasma membrane transporters, and receptor binding sites. However, notable recent breakthroughs in molecular imaging include the development of greatly improved tracers for subtypes of serotonin, cannabinoid, and metabotropic glutamate receptors, as well as noradrenaline transporters, amyloid-β and neuroinflammatory changes. This article reviews the considerable recent progress in preclinical PET and discusses applications relevant to a number of neurological and neuropsychiatric disorders in humans.
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Affiliation(s)
- Kanwar Virdee
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
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19
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Blockx I, Van Camp N, Verhoye M, Boisgard R, Dubois A, Jego B, Jonckers E, Raber K, Siquier K, Kuhnast B, Dollé F, Nguyen HP, Von Hörsten S, Tavitian B, Van der Linden A. Genotype specific age related changes in a transgenic rat model of Huntington's disease. Neuroimage 2011; 58:1006-16. [PMID: 21767653 DOI: 10.1016/j.neuroimage.2011.07.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 06/29/2011] [Accepted: 07/04/2011] [Indexed: 12/15/2022] Open
Abstract
We aimed to characterize the transgenic Huntington rat model with in vivo imaging and identify sensitive and reliable biomarkers associated with early and progressive disease status. In order to do so, we performed a multimodality (DTI and PET) longitudinal imaging study, during which the same TgHD and wildtype (Wt) rats were repetitively scanned. Surprisingly, the relative ventricle volume was smaller but increased faster in TgHD compared to Wt animals. DTI (mean, axial, radial diffusivity) revealed subtle genotype-specific aging effects in the striatum and its surrounding white matter, already in the presymptomatic stage. Using ¹⁸F-FDG and ¹⁸F-Fallypride PET imaging, we were not able to demonstrate genotype-specific aging effects within the striatum. The outcome of this longitudinal study was somewhat surprising as it demonstrated a significant differential aging pattern in TgHD versus Wt animals. Although it seems that the TgHD rat model does not have a sufficient expression of disease yet at the age of 12 months, further validation of this model is highly beneficial since there is still an incomplete understanding of the early disease mechanisms of Huntington's disease.
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Affiliation(s)
- Ines Blockx
- Bio-Imaging Lab, University of Antwerp, Belgium
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20
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Abstract
The natural plant alkaloids caffeine and theophylline were the first adenosine receptor (AR) antagonists described in the literature. They exhibit micromolar affinities and are non-selective. A large number of derivatives and analogues were subsequently synthesized and evaluated as AR antagonists. Very potent antagonists have thus been developed with selectivity for each of the four AR subtypes.
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Affiliation(s)
- Christa Müller
- PharmaCenter Bonn, Pharmaceutical Sciences Bonn (PSB), University of Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, An der Immenburg 4, D-53121 Bonn, Germany, Phone +49-228-73-2301, Fax +49-228-73-2567
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bldg. 8A, Rm. B1A-19, NIH, NIDDK, LBC, Bethesda, MD 20892, United States of America, Phone +1-301-496-9024, Fax +1-301-480-8422
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21
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Ishiwata K, Kimura Y, Oda K, Ishii K, Sakata M, Kawasaki K, Nariai T, Suzuki Y, Ishibashi K, Mishina M, Hashimoto M, Ishikawa M, Toyohara J. Development of PET radiopharmaceuticals and their clinical applications at the Positron Medical Center. Geriatr Gerontol Int 2010; 10 Suppl 1:S180-96. [PMID: 20590833 DOI: 10.1111/j.1447-0594.2010.00594.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Positron Medical Center has developed a large number of radiopharmaceuticals and 36 radiopharmaceuticals have been approved for clinical use for studying aging and geriatric diseases, especially brain functions. Positron emission tomography (PET) has been used to provide a highly advanced PET-based diagnosis. The current status of the development of radiopharmaceuticals, and representative clinical and methodological results are reviewed.
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Affiliation(s)
- Kiichi Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
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22
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Casteels C, Martinez E, Bormans G, Camon L, de Vera N, Baekelandt V, Planas AM, Van Laere K. Type 1 cannabinoid receptor mapping with [18F]MK-9470 PET in the rat brain after quinolinic acid lesion: a comparison to dopamine receptors and glucose metabolism. Eur J Nucl Med Mol Imaging 2010; 37:2354-63. [PMID: 20680268 DOI: 10.1007/s00259-010-1574-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 07/15/2010] [Indexed: 12/11/2022]
Abstract
PURPOSE Several lines of evidence imply early alterations in metabolic, dopaminergic and endocannabinoid neurotransmission in Huntington's disease (HD). Using [18F]MK-9470 and small animal PET, we investigated cerebral changes in type 1 cannabinoid (CB1) receptor binding in the quinolinic acid (QA) rat model of HD in relation to glucose metabolism, dopamine D2 receptor availability and amphetamine-induced turning behaviour. METHODS Twenty-one Wistar rats (11 QA and 10 shams) were investigated. Small animal PET acquisitions were conducted on a Focus 220 with approximately 18 MBq of [18F]MK-9470, [18F]FDG and [11C]raclopride. Relative glucose metabolism and parametric CB1 receptor and D2 binding images were anatomically standardized to Paxinos space and analysed voxel-wise using Statistical Parametric Mapping (SPM2). RESULTS In the QA model, [18F]MK-9470 uptake, glucose metabolism and D2 receptor binding were reduced in the ipsilateral caudate-putamen by 7, 35 and 77%, respectively (all p<2.10(-5)), while an increase for these markers was observed on the contralateral side (>5%, all p<7.10(-4)). [18F]MK-9470 binding was also increased in the cerebellum (p=2.10(-5)), where it was inversely correlated to the number of ipsiversive turnings (p=7.10(-6)), suggesting that CB1 receptor upregulation in the cerebellum is related to a better functional outcome. Additionally, glucose metabolism was relatively increased in the contralateral hippocampus, thalamus and sensorimotor cortex (p=1.10(-6)). CONCLUSION These data point to in vivo changes in endocannabinoid transmission, specifically for CB1 receptors in the QA model, with involvement of the caudate-putamen, but also distant regions of the motor circuitry, including the cerebellum. These data also indicate the occurrence of functional plasticity on metabolism, D2 and CB1 neurotransmission in the contralateral hemisphere.
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Affiliation(s)
- Cindy Casteels
- Division of Nuclear Medicine, KU Leuven and University Hospital Leuven, Leuven, Belgium.
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23
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Abstract
Advances in radiotracer chemistry have resulted in the development of novel molecular imaging probes for adenosine receptors (ARs). With the availability of these molecules, the function of ARs in human pathophysiology as well as the safety and efficacy of approaches to the different AR targets can now be determined. Molecular imaging is a rapidly growing field of research that allows the identification of molecular targets and functional processes in vivo. It is therefore gaining increasing interest as a tool in drug development because it permits the process of evaluating promising therapeutic targets to be stratified. Further, molecular imaging has the potential to evolve into a useful diagnostic tool, particularly for neurological and psychiatric disorders. This chapter focuses on currently available AR ligands that are suitable for molecular neuroimaging and describes first applications in healthy subjects and patients using positron emission tomography (PET).
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Affiliation(s)
- Andreas Bauer
- Institute of Neuroscience and Biophysics (INB-3), Research Center Jülich, 52425 Jülich, Germany.
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24
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Abstract
The development of potent and selective agonists and antagonists of adenosine receptors (ARs) has been a target of medicinal chemistry research for several decades, and recently the US Food and Drug Administration has approved Lexiscan, an adenosine derivative substituted at the 2 position, for use as a pharmacologic stress agent in radionuclide myocardial perfusion imaging. Currently, some other adenosine A(2A) receptor (A(2A)AR) agonists and antagonists are undergoing preclinical testing and clinical trials. While agonists are potent antiinflammatory agents also showing hypotensive effects, antagonists are being developed for the treatment of Parkinson's disease.However, since there are still major problems in this field, including side effects, low brain penetration (for the targeting of CNS diseases), short half-life, or lack of in vivo effects, the design and development of new AR ligands is a hot research topic.This review presents an update on the medicinal chemistry of A(2A)AR agonists and antagonists, and stresses the strong need for more selective ligands at the human A(2A)AR subtype, in particular in the case of agonists.
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Affiliation(s)
- Gloria Cristalli
- Dipartimento di Scienze Chimiche, Università di Camerino, 62032 Camerino (MC), Italy.
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25
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Affiliation(s)
- Masahiro Mishina
- Department of Neurological, Nephrological and Rheumatological Science, Graduate School of Medicine, Nippon Medical School
- Neurological Institute, Nippon Medical School Chiba Hokusoh Hospital
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26
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Mishina M, Ishiwata K, Kimura Y, Naganawa M, Oda K, Kobayashi S, Katayama Y, Ishii K. Evaluation of distribution of adenosine A2A receptors in normal human brain measured with [11C]TMSX PET. Synapse 2007; 61:778-84. [PMID: 17568431 DOI: 10.1002/syn.20423] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Adenosine A(2A) receptor (A2AR) is thought to interact with dopamine D(2) receptor. Selective A2AR antagonists have attracted attention as the treatment of Parkinson's disease. In this study, we investigated the distribution of the A2ARs in the living human brain using positron emission tomography (PET) and [7-methyl-(11)C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([(11)C]TMSX). We recruited five normal male subjects. A dynamic series of PET scans was performed for 60 min, and the arterial blood was sampled during the scan to measure radioactivity of the parent compound and labeled metabolites. Circular regions of interest of 10-mm diameter were placed in the PET images over the cerebellum, brainstem, thalamus, head of caudate nucleus, anterior and posterior putamen, frontal lobe, temporal lobe, parietal lobe, occipital lobe, and posterior cingulate gyrus for each subject. A two-tissue, three-compartment model was used to estimate K(1), k(2), k(3), and k(4) between metabolite-corrected plasma and tissue time activity of [(11)C]TMSX. The binding potential (BP) was the largest in the anterior (1.25) and posterior putamen (1.20), was next largest in the head of caudate nucleus (1.05) and thalamus (1.03), and was small in the cerebral cortex, especially frontal lobe (0.46). [(11)C]TMSX PET showed the largest BP in the striatum in which A2ARs were enriched as in postmortem and nonhuman studies reported, but that the binding of [(11)C]TMSX was relatively larger in the thalamus to compare with other mammals. To date, [(11)C]TMSX is the only promising PET ligand, which is available to clinical use for mapping the A2ARs in the living human brain.
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Affiliation(s)
- Masahiro Mishina
- Neurological Institute, Nippon Medical School Chiba-Hokusoh Hospital, Imba-gun, Chiba-ken 270-1694, Japan
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Schiffmann SN, Fisone G, Moresco R, Cunha RA, Ferré S. Adenosine A2A receptors and basal ganglia physiology. Prog Neurobiol 2007; 83:277-92. [PMID: 17646043 PMCID: PMC2148496 DOI: 10.1016/j.pneurobio.2007.05.001] [Citation(s) in RCA: 275] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2006] [Revised: 03/30/2007] [Accepted: 05/29/2007] [Indexed: 12/20/2022]
Abstract
Adenosine A2A receptors are highly enriched in the basal ganglia system. They are predominantly expressed in enkephalin-expressing GABAergic striatopallidal neurons and therefore are highly relevant to the function of the indirect efferent pathway of the basal ganglia system. In these GABAergic enkephalinergic neurons, the A2A receptor tightly interacts structurally and functionally with the dopamine D2 receptor. Both by forming receptor heteromers and by targeting common intracellular signaling cascades, A2A and D2 receptors exhibit reciprocal antagonistic interactions that are central to the function of the indirect pathway and hence to basal ganglia control of movement, motor learning, motivation and reward. Consequently, this A2A/D2 receptors antagonistic interaction is also central to basal ganglia dysfunction in Parkinson's disease. However, recent evidence demonstrates that, in addition to this post-synaptic site of action, striatal A2A receptors are also expressed and have physiological relevance on pre-synaptic glutamatergic terminals of the cortico-limbic-striatal and thalamo-striatal pathways, where they form heteromeric receptor complexes with adenosine A1 receptors. Therefore, A2A receptors play an important fine-tuning role, boosting the efficiency of glutamatergic information flow in the indirect pathway by exerting control, either pre- and/or post-synaptically, over other key modulators of glutamatergic synapses, including D2 receptors, group I metabotropic mGlu5 glutamate receptors and cannabinoid CB1 receptors, and by triggering the cAMP-protein kinase A signaling cascade.
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Affiliation(s)
- S N Schiffmann
- Laboratory of Neurophysiology, Université Libre de Bruxelles, Campus Erasme, 808 route de Lennik, CP601, 1070 Brussels, Belgium.
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Strome EM, Doudet DJ. Animal Models of Neurodegenerative Disease: Insights from In vivo Imaging Studies. Mol Imaging Biol 2007; 9:186-95. [PMID: 17357857 DOI: 10.1007/s11307-007-0093-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Animal models have been used extensively to understand the etiology and pathophysiology of human neurodegenerative diseases, and are an essential component in the development of therapeutic interventions for these disorders. In recent years, technical advances in imaging modalities such as positron emission tomography (PET) and magnetic resonance imaging (MRI) have allowed the use of these techniques for the evaluation of functional, neurochemical, and anatomical changes in the brains of animals. Combining animal models of neurodegenerative disorders with neuroimaging provides a powerful tool to follow the disease process, to examine compensatory mechanisms, and to investigate the effects of potential treatments preclinically to derive knowledge that will ultimately inform our clinical decisions. This article reviews the literature on the use of PET and MRI in animal models of Parkinson's disease, Huntington's disease, and Alzheimer's disease, and evaluates the strengths and limitations of brain imaging in animal models of neurodegenerative diseases.
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Affiliation(s)
- Elissa M Strome
- Pacific Parkinson's Research Centre, University of British Columbia, Vancouver, Canada.
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Nikolaus S, Larisch R, Beu M, Antke C, Kley K, Forutan F, Wirrwar A, Müller HW. Investigating the Dopaminergic Synapse In Vivo. II. Molecular Imaging Studies in Small Laboratory Animals. Rev Neurosci 2007; 18:473-504. [DOI: 10.1515/revneuro.2007.18.6.473] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bauer A, Zilles K, Matusch A, Holzmann C, Riess O, von Hörsten S. Regional and subtype selective changes of neurotransmitter receptor density in a rat transgenic for the Huntington's disease mutation. J Neurochem 2005; 94:639-50. [PMID: 16033418 DOI: 10.1111/j.1471-4159.2005.03169.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Huntington's disease (HD) is an autosomal dominantly inherited progressive neurodegenerative disorder caused by a CAG/polyglutamine repeat expansion in the gene encoding the huntingtin protein. We have recently generated a rat model transgenic for HD, which displays a slowly progressive phenotype resembling the human adult-onset type of disease. In this study we systematically assessed the distribution and density of 17 transmitter receptors in the brains of 2-year-old rats using quantitative multi-tracer autoradiography and high-resolution positron emission tomography. Heterozygous animals expressed increased densities of M(2) acetylcholine (increase of 148 +/- 16% of controls; p > 0.001; n = 7), nicotine (increase of 149 +/- 16% of controls; p > 0.01; n = 6), and alpha(2) noradrenergic receptors (increase of 141 +/- 15% of controls; p > 0.001; n = 6), respectively. Densities of these receptors were decreased in homozygous animals. Decreases of receptor density in both hetero- and homozygous animals were found for M1 acetylcholine, 5-HT 2A serotonin, A 2A adenosine, D1 and D2 dopamine, and GABA(A) receptors, respectively. Other investigated receptor systems showed small changes or were not affected. The present data suggest that the moderate increase of CAG/polyglutamine repeat expansions in the present rat model of Huntington's disease is characterized by subtype-selective and region-specific changes of neuroreceptor densities. In particular, there is evidence for a contribution of predominantly presynaptically localized cholinergic and noradrenergic receptors in the response to Huntington's disease pathology.
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Affiliation(s)
- Andreas Bauer
- Institute of Medicine, Research Center Jülich, Jülich, Germany.
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Cunha RA. Neuroprotection by adenosine in the brain: From A(1) receptor activation to A (2A) receptor blockade. Purinergic Signal 2005; 1:111-34. [PMID: 18404497 PMCID: PMC2096528 DOI: 10.1007/s11302-005-0649-1] [Citation(s) in RCA: 404] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Accepted: 11/10/2004] [Indexed: 12/11/2022] Open
Abstract
Adenosine is a neuromodulator that operates via the most abundant inhibitory adenosine A(1) receptors (A(1)Rs) and the less abundant, but widespread, facilitatory A(2A)Rs. It is commonly assumed that A(1)Rs play a key role in neuroprotection since they decrease glutamate release and hyperpolarize neurons. In fact, A(1)R activation at the onset of neuronal injury attenuates brain damage, whereas its blockade exacerbates damage in adult animals. However, there is a down-regulation of central A(1)Rs in chronic noxious situations. In contrast, A(2A)Rs are up-regulated in noxious brain conditions and their blockade confers robust brain neuroprotection in adult animals. The brain neuroprotective effect of A(2A)R antagonists is maintained in chronic noxious brain conditions without observable peripheral effects, thus justifying the interest of A(2A)R antagonists as novel protective agents in neurodegenerative diseases such as Parkinson's and Alzheimer's disease, ischemic brain damage and epilepsy. The greater interest of A(2A)R blockade compared to A(1)R activation does not mean that A(1)R activation is irrelevant for a neuroprotective strategy. In fact, it is proposed that coupling A(2A)R antagonists with strategies aimed at bursting the levels of extracellular adenosine (by inhibiting adenosine kinase) to activate A(1)Rs might constitute the more robust brain neuroprotective strategy based on the adenosine neuromodulatory system. This strategy should be useful in adult animals and especially in the elderly (where brain pathologies are prevalent) but is not valid for fetus or newborns where the impact of adenosine receptors on brain damage is different.
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Affiliation(s)
- Rodrigo A Cunha
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Coimbra, Portugal,
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Moresco RM, Todde S, Belloli S, Simonelli P, Panzacchi A, Rigamonti M, Galli-Kienle M, Fazio F. In vivo imaging of adenosine A2A receptors in rat and primate brain using [11C]SCH442416. Eur J Nucl Med Mol Imaging 2004; 32:405-13. [PMID: 15549298 DOI: 10.1007/s00259-004-1688-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Accepted: 08/20/2004] [Indexed: 11/27/2022]
Abstract
PURPOSE The aim of this study was to evaluate the suitability of [11C]SCH442416 for the in vivo imaging of adenosine A2A receptors. METHODS In rats and Macaca nemestrina, we evaluated the time course of the cerebral distribution of [11C]SCH442416. Furthermore, in rats we investigated the rate of metabolic degradation, the inhibitory effects of different drugs acting on adenosine or dopamine receptors and the modification induced by the intrastriatal administration of quinolinic acid (QA). RESULTS The rate of metabolic degradation of [11C]SCH442416 in rats was slow; 60 min after tracer injection, more than 40% of total plasma activity was due to unmetabolised [11C]SCH442416. At the time of maximum uptake, radioactive metabolites represented only 6% of total extractable activity in the cerebellum and less than 1% in the striatum. In the striatum, the region with the highest expression of A2A receptors, the in vivo uptake of [11C]SCH442416 was significantly reduced only by drugs acting on A2A receptors or by QA, a neurotoxin that selectively reduces the number of intrastriatal GABAergic neurons. Position emission tomography (PET) studies in monkeys indicated that the tracer rapidly accumulates in brain, reaching maximum uptake between 5 and 10 min. Twenty minutes after the injection, radioactivity concentration in the striatum was two times that in the cerebellum. CONCLUSION The specificity of binding, the rank order of regional distribution in the brain of rats and M. nemestrina, the good signal to noise ratios and the low amount of radioactive metabolites in brain and periphery indicate that [11C]SCH442416 is a promising tracer for the in vivo imaging of A2A adenosine receptors using PET.
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Affiliation(s)
- R M Moresco
- IBFM-CNR, University of Milan-Bicocca, Scientific Institute H San Raffaele, Milan, Italy.
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Ishiwata K, Kawamura K, Kimura Y, Oda K, Ishii K. Potential of an adenosine A2A receptor antagonist [11C]TMSX for myocardial imaging by positron emission tomography: a first human study. Ann Nucl Med 2004; 17:457-62. [PMID: 14575379 DOI: 10.1007/bf03006434] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In previous in vivo studies with mice, rats, cats and monkeys, we have demonstrated that [7-methyl-11C]-(E)-8-(3,4,5-trimethoxystyryl)- 1,3,7-trimethylxanthine ([11C]TMSX) is a potential radioligand for mapping adenosine A2A receptors of the brain by positron emission tomography (PET). In the present study, we studied the potential of [11C]TMSX for myocardial imaging. Uptake of radioactivity by the heart was high and gradually decreased after an intravenous injection of [11C]TMSX into mice. In metabolite analysis, 54% and 76% of the radioactivity in plasma and heart, respectively, were present as the unchanged form of [11C]TMSX 60 min postinjection. The myocardial uptake was reduced by carrier-loading and by co-injection of an adenosine A2A antagonist CSC, but not by co-injection of an adenosine A1 antagonist DPCPX. Pretreatment with a high dose of a non-selective antagonist theophylline also reduced the myocardial uptake of [11C]TMSX. These findings demonstrate the specific binding of [11C]TMSX to adenosine A2A receptors in the heart. Finally we successfully performed the myocardial imaging by PET with [11C]TMSX in a normal volunteer. A graphical analysis by Logan plot supported the receptor-mediated uptake of [11C]TMSX. Peripherally [11C]TMSX was very stable in human: >90% of the radioactivity in plasma was detected as the unchanged form in a 60-min study. We concluded that [11C]TMSX PET has the potential for myocardial imaging.
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Affiliation(s)
- Kiichi Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Japan.
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Ginovart N, Sun W, Wilson AA, Houle S, Kapur S. Quantitative validation of an intracerebral ?-sensitive microprobe system to determine in vivo drug-induced receptor occupancy using [11C]raclopride in rats. Synapse 2004; 52:89-99. [PMID: 15034915 DOI: 10.1002/syn.20010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this study, we evaluated the potential of using a new beta-sensitive microprobe system for in vivo quantification of [11C]raclopride binding and for in vivo determination of drug-induced receptor occupancy in the rat striatum. To validate this system, an ex vivo tissue dissection method was used to corroborate in vivo beta-microprobe measurements. Our data showed that the beta-microprobe-derived [11C]raclopride binding kinetics in striatum could be quantified using a tissue compartmental model with a cerebellar reference region. Haloperidol (0.001-0.1 mg/kg; i.v.) induced a dose-dependent decrease in [11C]raclopride binding in striatum as measured using the beta-microprobe with an ED50 value of 0.013 mg/kg. Highly significant relationships (P < 0.0001) were observed, within the same animals, between in vivo and ex vivo measures of haloperidol-induced D2-receptor occupancy (r = 0.98) as well as between in vivo and ex vivo measures of [11C]raclopride binding potentials (r = 0.99). Results from pretreatment and displacement studies with unlabeled raclopride and amphetamine conformed to the effect of these drugs as observed in humans using [11C]raclopride and PET and allowed estimation of the in vivo k(off) value of raclopride to 0.025 +/- 0.004 min(-1). However, allowing the system to stabilize before measurements and shielding the photomultiplier tubes were critical for obtaining these consistent results. This study demonstrates that the beta-microprobe provides reliable measurements of [11C]raclopride binding kinetics in rodents, allows for quantitative in vivo measurements of antipsychotic drug action in brain, and represents a valid and cost-effective alternative to positron emission tomography imaging in small animals.
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Affiliation(s)
- Nathalie Ginovart
- PET Centre, Centre for Addiction and Mental Health and University of Toronto, Toronto, Ontario M5T 1R8, Canada.
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Ishiwata K, Wang WF, Kimura Y, Kawamura K, Ishii K. Preclinical studies on [11C]TMSX for mapping adenosine A2A receptors by positron emission tomography. Ann Nucl Med 2003; 17:205-11. [PMID: 12846542 DOI: 10.1007/bf02990023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In previous in vivo studies with mice, rats and monkeys, we have demonstrated that [11C]TMSX ([7-methyl-11C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine) is a potential radioligand for mapping adenosine A2A receptors of the brain by positron emission tomography (PET). In the present study, we performed a preclinical study. A suitable preparation method for [11C]TMSX injection was established. The radiation absorbed-dose by [11C]TMSX in humans estimated from the tissue distribution in mice was low enough for clinical use, and the acute toxicity and mutagenicity of TMSX were not found. The striatal uptake of [11C]TMSX in mice was reduced by pretreatment with theophylline at the dose of 10 and 100 mg/kg, suggesting that the [11C]TMSX PET should be carefully performed in the patients received with theophylline. We have concluded that [11C]TMSX is suitable for mapping adenosine A2A receptors in the human brain by PET.
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Affiliation(s)
- Kiichi Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Japan.
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