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Ikoma Y, Takuwa H, Nishino A, Maeda J, Kawamura K, Obata T, Zhang MR, Higuchi M, Suhara T. Measurement of changes in endogenous serotonin level by positron emission tomography with [ 18F]altanserin. Ann Nucl Med 2021; 35:955-965. [PMID: 34101154 DOI: 10.1007/s12149-021-01633-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 05/18/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Positron emission tomography (PET) has been used to investigate changes in the concentration of endogenous neurotransmitters. Recently, this technique has been applied to the imaging of serotonin2A receptors using [18F]altanserin. In these measurements, a reduction in binding potential (BP) suggests an increase in endogenous serotonin levels caused by pharmacological or cognitive stimulations, and the sensitivity of BP reduction depends on the characteristics of [18F]altanserin. In this study, we evaluated an analytical method for estimating the changes in endogenous serotonin levels based on PET scans with [18F]altanserin at baseline and stimulated states and validated it using simulations and small animal PET studies. METHODS First, in the simulations, the time-activity curves at baseline and the stimulated states were generated using an extended compartment model including the competition for the receptors between the administered [18F]altanserin and endogenous serotonin. In the stimulated state, the magnitude and onset of the endogenous serotonin elevation were altered to varying degrees. In these time-activity curves, BP was estimated using the simplified reference tissue model (SRTM), and the reduction in BP was evaluated by comparison with that of the baseline state. Next, the proposed method was applied to mouse PET studies. Endogenous serotonin levels were elevated by treatment with selective serotonin reuptake inhibitors (SSRIs), and PET studies were performed twice, once with and once without treatment. In both scans, BP was estimated using the SRTM with the cerebellum as a reference region, and the reduction in BP after SSRI treatment was evaluated. RESULTS In the simulations, the BP estimate of the stimulated state was smaller than that of the baseline state, and their reduction was related to the amount of change in the serotonin concentration. BP reduction was also affected by the onset of serotonin elevation. In the mouse studies, the BP of the cerebral cortex decreased in the scans with SSRI treatment. CONCLUSIONS The reduction in BP estimated using the SRTM from [18F]altanserin-PET studies at baseline and in stimulated states can detect changes in the binding conditions of serotonin2A receptors. This may be useful for investigating the elevation of endogenous serotonin levels caused by stimulations.
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Affiliation(s)
- Yoko Ikoma
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
| | - Hiroyuki Takuwa
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Asuka Nishino
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
- Department of Biological Sciences, Faculty of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Jun Maeda
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Kazunori Kawamura
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Takayuki Obata
- Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Ming-Rong Zhang
- Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Makoto Higuchi
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Tetsuya Suhara
- Department of Functional Brain Imaging, Institute for Quantum Medical Science, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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Willmann M, Hegger J, Neumaier B, Ermert J. Radiosynthesis and Biological Evaluation of [ 18F]R91150, a Selective 5-HT 2A Receptor Antagonist for PET-Imaging. ACS Med Chem Lett 2021; 12:738-744. [PMID: 34055220 DOI: 10.1021/acsmedchemlett.0c00658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 03/30/2021] [Indexed: 12/21/2022] Open
Abstract
Serotonergic 5-HT2A receptors in cortical and forebrain regions are an important substrate for the neuromodulatory actions of serotonin in the brain. They have been implicated in the etiology of many neuropsychiatric disorders and serve as a target for antipsychotic, antidepressant, and anxiolytic drugs. Positron emission tomography imaging using suitable radioligands can be applied for in vivo quantification of receptor densities and receptor occupancy for therapy evaluation. Recently, the radiosynthesis of the selective 5-HT2AR antagonist [18F]R91150 was reported. However, the six-step radiosynthesis is cumbersome and time-consuming with low radiochemical yields (RCYs) of <5%. In this work, [18F]R91150 was prepared using late-stage Cu-mediated radiofluorination to simplify its synthesis. The detailed protocol enabled us to obtain RCYs of 14 ± 1%, and the total synthesis time was reduced to 60 min. In addition, autoradiographic studies with [18F]R91150 in rat brain slices revealed the typical uptake pattern of 5-HT2A receptor ligands.
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Affiliation(s)
- Michael Willmann
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
| | - Julian Hegger
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
- Uniklinik Köln, Institute of Radiochemistry and Experimental Molecular Imaging, 50937 Köln, Germany
| | - Johannes Ermert
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, INM-5, Nuclear Chemistry (INM-5), 52425 Jülich, Germany
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Abstract
Positron emission tomography (PET) is a non-invasive imaging technology employed to describe metabolic, physiological, and biochemical processes in vivo. These include receptor availability, metabolic changes, neurotransmitter release, and alterations of gene expression in the brain. Since the introduction of dedicated small-animal PET systems along with the development of many novel PET imaging probes, the number of PET studies using rats and mice in basic biomedical research tremendously increased over the last decade. This article reviews challenges and advances of quantitative rodent brain imaging to make the readers aware of its physical limitations, as well as to inspire them for its potential applications in preclinical research. In the first section, we briefly discuss the limitations of small-animal PET systems in terms of spatial resolution and sensitivity and point to possible improvements in detector development. In addition, different acquisition and post-processing methods used in rodent PET studies are summarized. We further discuss factors influencing the test-retest variability in small-animal PET studies, e.g., different receptor quantification methodologies which have been mainly translated from human to rodent receptor studies to determine the binding potential and changes of receptor availability and radioligand affinity. We further review different kinetic modeling approaches to obtain quantitative binding data in rodents and PET studies focusing on the quantification of endogenous neurotransmitter release using pharmacological interventions. While several studies have focused on the dopamine system due to the availability of several PET tracers which are sensitive to dopamine release, other neurotransmitter systems have become more and more into focus and are described in this review, as well. We further provide an overview of latest genome engineering technologies, including the CRISPR/Cas9 and DREADD systems that may advance our understanding of brain disorders and function and how imaging has been successfully applied to animal models of human brain disorders. Finally, we review the strengths and opportunities of simultaneous PET/magnetic resonance imaging systems to study drug-receptor interactions and challenges for the translation of PET results from bench to bedside.
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Pauwelyn G, Vlerick L, Dockx R, Verhoeven J, Dobbeleir A, Bosmans T, Peremans K, Vanhove C, Polis I, De Vos F. Kinetic analysis of [ 18F] altanserin bolus injection in the canine brain using PET imaging. BMC Vet Res 2019; 15:415. [PMID: 31752848 PMCID: PMC6873736 DOI: 10.1186/s12917-019-2165-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Currently, [18F] altanserin is the most frequently used PET-radioligand for serotonin2A (5-HT2A) receptor imaging in the human brain but has never been validated in dogs. In vivo imaging of this receptor in the canine brain could improve diagnosis and therapy of several behavioural disorders in dogs. Furthermore, since dogs are considered as a valuable animal model for human psychiatric disorders, the ability to image this receptor in dogs could help to increase our understanding of the pathophysiology of these diseases. Therefore, five healthy laboratory beagles underwent a 90-min dynamic PET scan with arterial blood sampling after [18F] altanserin bolus injection. Compartmental modelling using metabolite corrected arterial input functions was compared with reference tissue modelling with the cerebellum as reference region. RESULTS The distribution of [18F] altanserin in the canine brain corresponded well to the distribution of 5-HT2A receptors in human and rodent studies. The kinetics could be best described by a 2-Tissue compartment (2-TC) model. All reference tissue models were highly correlated with the 2-TC model, indicating compartmental modelling can be replaced by reference tissue models to avoid arterial blood sampling. CONCLUSIONS This study demonstrates that [18F] altanserin PET is a reliable tool to visualize and quantify the 5-HT2A receptor in the canine brain.
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Affiliation(s)
- Glenn Pauwelyn
- Laboratory of Radiopharmacy, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
| | - Lise Vlerick
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Robrecht Dockx
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.,Department of Psychiatry and Medical Psychology, Ghent University, Ghent, Belgium
| | - Jeroen Verhoeven
- Laboratory of Radiopharmacy, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Andre Dobbeleir
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.,Department of Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Tim Bosmans
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Kathelijne Peremans
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Christian Vanhove
- Institute Biomedical Technology - Medisip - Infinity, Ghent University, Ghent, Belgium
| | - Ingeborgh Polis
- Small animal Departments, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Filip De Vos
- Laboratory of Radiopharmacy, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
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Ishii T, Kimura Y, Ichise M, Takahata K, Kitamura S, Moriguchi S, Kubota M, Zhang MR, Yamada M, Higuchi M, Okubo Y, Suhara T. Anatomical relationships between serotonin 5-HT2A and dopamine D2 receptors in living human brain. PLoS One 2017; 12:e0189318. [PMID: 29220382 PMCID: PMC5722317 DOI: 10.1371/journal.pone.0189318] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/22/2017] [Indexed: 11/18/2022] Open
Abstract
Serotonin 2A (5-HT2A) receptors and dopamine D2 receptors are intimately related to the physiology and pathophysiology of neuropsychiatric disorders. A large number of studies have reported the effectiveness of psychotropic agents targeting 5-HT2A and D2 receptors in these disorders. In addition to the individual functions of these receptors, the interaction between the two neurotransmitter systems has been studied in the living brain. However, little is known about their regional relationship in individual human brains. We investigated regional relationships between 5-HT2A and D2 receptors using positron emission tomography (PET) and a bicluster analysis of the correlation matrix of individual variation in the two receptor densities to identify groups of distinctive regional correlations between the two receptors.
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Affiliation(s)
- Tatsuya Ishii
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
- Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan
| | - Yasuyuki Kimura
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
- Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan
- * E-mail:
| | - Masanori Ichise
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Keisuke Takahata
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Soichiro Kitamura
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Sho Moriguchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Manabu Kubota
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Ming-Rong Zhang
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Makiko Yamada
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Makoto Higuchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Yoshinori Okubo
- Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan
| | - Tetsuya Suhara
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
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Kroll T, Elmenhorst D, Matusch A, Celik AA, Wedekind F, Weisshaupt A, Beer S, Bauer A. [¹⁸F]Altanserin and small animal PET: impact of multidrug efflux transporters on ligand brain uptake and subsequent quantification of 5-HT₂A receptor densities in the rat brain. Nucl Med Biol 2013; 41:1-9. [PMID: 24120220 DOI: 10.1016/j.nucmedbio.2013.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 09/04/2013] [Accepted: 09/06/2013] [Indexed: 12/14/2022]
Abstract
INTRODUCTION The selective 5-hydroxytryptamine type 2a receptor (5-HT(2A)R) radiotracer [(18)F]altanserin is a promising ligand for in vivo brain imaging in rodents. However, [(18)F]altanserin is a substrate of P-glycoprotein (P-gp) in rats. Its applicability might therefore be constrained by both a differential expression of P-gp under pathological conditions, e.g. epilepsy, and its relatively low cerebral uptake. The aim of the present study was therefore twofold: (i) to investigate whether inhibition of multidrug transporters (MDT) is suitable to enhance the cerebral uptake of [(18)F]altanserin in vivo and (ii) to test different pharmacokinetic, particularly reference tissue-based models for exact quantification of 5-HT(2A)R densities in the rat brain. METHODS Eighteen Sprague-Dawley rats, either treated with the MDT inhibitor cyclosporine A (CsA, 50 mg/kg, n=8) or vehicle (n=10) underwent 180-min PET scans with arterial blood sampling. Kinetic analyses of tissue time-activity curves (TACs) were performed to validate invasive and non-invasive pharmacokinetic models. RESULTS CsA application lead to a two- to threefold increase of [(18)F]altanserin uptake in different brain regions and showed a trend toward higher binding potentials (BP(ND)) of the radioligand. CONCLUSIONS MDT inhibition led to an increased cerebral uptake of [(18)F]altanserin but did not improve the reliability of BP(ND) as a non-invasive estimate of 5-HT(2A)R. This finding is most probable caused by the heterogeneous distribution of P-gp in the rat brain and its incomplete blockade in the reference region (cerebellum). Differential MDT expressions in experimental animal models or pathological conditions are therefore likely to influence the applicability of imaging protocols and have to be carefully evaluated.
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Affiliation(s)
- Tina Kroll
- Institute of Neuroscience and Medicine, INM-2, Forschungszentrum Jülich GmbH, Jülich, Germany.
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