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Schalbroeck R, van Hooijdonk CFM, Bos DPA, Booij J, Selten JP. Chronic social stressors and striatal dopamine functioning in humans: A systematic review of SPECT and PET studies. Mol Psychiatry 2024:10.1038/s41380-024-02581-x. [PMID: 38760501 DOI: 10.1038/s41380-024-02581-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 04/18/2024] [Accepted: 04/22/2024] [Indexed: 05/19/2024]
Abstract
The dopamine hypothesis of schizophrenia posits that elevated striatal dopamine functioning underlies the development of psychotic symptoms. Chronic exposure to social stressors increases psychosis risk, possibly by upregulating striatal dopamine functioning. Here we systematically review single photon emission computed tomography (SPECT) and positron emission tomography (PET) studies that examined the relationship between chronic social stress exposure and in vivo striatal dopamine functioning in humans. We searched the scientific databases PubMed and PsycINFO from inception to August 2023. The quality of the included studies was evaluated with the ten-item Observational Study Quality Evaluation (PROSPERO: CRD42022308883). Twenty-eight studies were included, which measured different aspects of striatal dopamine functioning including dopamine synthesis capacity (DSC), vesicular monoamine transporter type 2 binding, dopamine release following a pharmacological or behavioral challenge, D2/3 receptor binding, and dopamine transporter binding. We observed preliminary evidence of an association between childhood trauma and increased striatal DSC and dopamine release. However, exposure to low socioeconomic status, stressful life events, or other social stressors was not consistently associated with altered striatal dopamine functioning. The quality of available studies was generally low. In conclusion, there is insufficient evidence that chronic social stressors upregulate striatal dopamine functioning in humans. We propose avenues for future research, in particular to improve the measurement of chronic social stressors and the methodological quality of study designs.
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Affiliation(s)
- Rik Schalbroeck
- Mental Health and Neuroscience Research Institute, Maastricht University, Maastricht, The Netherlands.
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
| | - Carmen F M van Hooijdonk
- Mental Health and Neuroscience Research Institute, Maastricht University, Maastricht, The Netherlands
| | - Daniëlle P A Bos
- Department of Psychiatry, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jean-Paul Selten
- Mental Health and Neuroscience Research Institute, Maastricht University, Maastricht, The Netherlands
- Rivierduinen Institute for Mental Healthcare, Leiden, The Netherlands
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2
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Meana JJ, González-Maeso J. Serotonin 5-HT 2A receptors in schizophrenia: Reflexions on an unfinished story. Eur Neuropsychopharmacol 2023; 74:89-91. [PMID: 37352762 DOI: 10.1016/j.euroneuro.2023.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 05/22/2023] [Accepted: 05/26/2023] [Indexed: 06/25/2023]
Affiliation(s)
- J Javier Meana
- Department of Pharmacology, University of the Basque Country, UPV/EHU, 48940 Leioa, Bizkaia, Spain; Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Spain; Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Bizkaia, Spain.
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
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van Hooijdonk CFM, van der Pluijm M, Bosch I, van Amelsvoort TAMJ, Booij J, de Haan L, Selten JP, Giessen EVD. The substantia nigra in the pathology of schizophrenia: A review on post-mortem and molecular imaging findings. Eur Neuropsychopharmacol 2023; 68:57-77. [PMID: 36640734 DOI: 10.1016/j.euroneuro.2022.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 01/14/2023]
Abstract
Dysregulation of striatal dopamine is considered to be an important driver of pathophysiological processes in schizophrenia. Despite being one of the main origins of dopaminergic input to the striatum, the (dys)functioning of the substantia nigra (SN) has been relatively understudied in schizophrenia. Hence, this paper aims to review different molecular aspects of nigral functioning in patients with schizophrenia compared to healthy controls by integrating post-mortem and molecular imaging studies. We found evidence for hyperdopaminergic functioning in the SN of patients with schizophrenia (i.e. increased AADC activity in antipsychotic-free/-naïve patients and elevated neuromelanin accumulation). Reduced GABAergic inhibition (i.e. decreased density of GABAergic synapses, lower VGAT mRNA levels and lower mRNA levels for GABAA receptor subunits), excessive glutamatergic excitation (i.e. increased NR1 and Glur5 mRNA levels and a reduced number of astrocytes), and several other disturbances implicating the SN (i.e. immune functioning and copper concentrations) could potentially underlie this nigral hyperactivity and associated striatal hyperdopaminergic functioning in schizophrenia. These results highlight the importance of the SN in schizophrenia pathology and suggest that some aspects of molecular functioning in the SN could potentially be used as treatment targets or biomarkers.
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Affiliation(s)
- Carmen F M van Hooijdonk
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), University of Maastricht, Maastricht, the Netherlands; Rivierduinen, Institute for Mental Health Care, Leiden, the Netherlands.
| | - Marieke van der Pluijm
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Iris Bosch
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Therese A M J van Amelsvoort
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), University of Maastricht, Maastricht, the Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Lieuwe de Haan
- Department of Psychiatry, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Jean-Paul Selten
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), University of Maastricht, Maastricht, the Netherlands; Rivierduinen, Institute for Mental Health Care, Leiden, the Netherlands
| | - Elsmarieke van de Giessen
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, the Netherlands
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4
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Frankle WG, Himes M, Mason NS, Mathis CA, Narendran R. Prefrontal and Striatal Dopamine Release Are Inversely Correlated in Schizophrenia. Biol Psychiatry 2022; 92:791-799. [PMID: 35791965 DOI: 10.1016/j.biopsych.2022.05.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 04/19/2022] [Accepted: 05/02/2022] [Indexed: 11/17/2022]
Abstract
BACKGROUND The dopamine (DA) hypothesis postulates hyperactivity of subcortical DA transmission and hypoactivity of cortical DA in schizophrenia (SCH). Positron emission tomography provides the ability to assess this hypothesis in humans. However, no studies have examined the relationship between cortical DA and striatal DA in this illness. METHODS D2/3 receptor radiotracer [11C]FLB457 BPND (binding potential relative to nondisplaceable uptake) was measured in 14 off-medication subjects with SCH and 14 healthy control (HC) subjects at baseline and after the administration of 0.5 mg/kg oral d-amphetamine. The amphetamine-induced change in BPND (ΔBPND) was calculated as the difference between BPND in the postamphetamine condition and BPND in the baseline condition and expressed as a percentage of BPND at baseline. DA release in the striatum using the radiotracer [11C]NPA was also measured in these subjects. RESULTS [11C]FLB457 ΔBPND was greater in the HC group compared with the SCH group (F1,26 = 5.7; p = .02) with significant differences in [11C]FLB457 ΔBPND seen across cortical brain regions. Only in the SCH group was a significant negative correlation observed between [11C]FLB457 ΔBPND in the dorsolateral prefrontal cortex and [11C]NPA ΔBPND in the dorsal caudate (r = -0.71, p = .005). CONCLUSIONS Subjects with SCH demonstrated deficits of DA release in cortical brain regions relative to HC subjects. Examining both cortical and striatal DA release in the same subjects demonstrated an inverse relationship between cortical DA release and striatal DA release in SCH not present in HC subjects, providing support for the current DA hypothesis of SCH.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, NYU Langone Medical Center, New York, New York.
| | - Michael Himes
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - N Scott Mason
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Chester A Mathis
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rajesh Narendran
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
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5
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Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
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Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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6
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Kho W, von Haefen C, Paeschke N, Nasser F, Endesfelder S, Sifringer M, González-López A, Lanzke N, Spies CD. Dexmedetomidine Restores Autophagic Flux, Modulates Associated microRNAs and the Cholinergic Anti-inflammatory Pathway upon LPS-Treatment in Rats. J Neuroimmune Pharmacol 2022; 17:261-276. [PMID: 34357471 PMCID: PMC9726767 DOI: 10.1007/s11481-021-10003-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 06/26/2021] [Indexed: 12/29/2022]
Abstract
Infections and perioperative stress can lead to neuroinflammation, which in turn is linked to cognitive impairments such as postoperative delirium or postoperative cognitive dysfunctions. The α2-adrenoceptor agonist dexmedetomidine (DEX) prevents cognitive impairments and has organo-protective and anti-inflammatory properties. Macroautophagy (autophagy) regulates many biological processes, but its role in DEX-mediated anti-inflammation and the underlying mechanism of DEX remains largely unclear. We were interested how a pretreatment with DEX protects against lipopolysaccharide (LPS)-induced inflammation in adult male Wistar rats. We used Western blot and activity assays to study how DEX modulated autophagy- and apoptosis-associated proteins as well as molecules of the cholinergic anti-inflammatory pathway, and qPCR to analyse the expression of autophagy and inflammation-associated microRNAs (miRNA) in the spleen, cortex and hippocampus at different time points (6 h, 24 h, 7 d). We showed that a DEX pretreatment prevents LPS-induced impairments in autophagic flux and attenuates the LPS-induced increase in the apoptosis-associated protein cleaved poly(ADP-ribose)-polymerase (PARP) in the spleen. Both, DEX and LPS altered miRNA expression and molecules of the cholinergic anti-inflammatory pathway in the spleen and brain. While only a certain set of miRNAs was up- and/or downregulated by LPS in each tissue, which was prevented or attenuated by a DEX pretreatment in the spleen and hippocampus, all miRNAs were up- and/or downregulated by DEX itself - independent of whether or not they were altered by LPS. Our results indicate that the organo-protective effect of DEX may be mediated by autophagy, possibly by acting on associated miRNAs, and the cholinergic anti-inflammatory pathway. Preventive effects of DEX on LPS-induced inflammation. DEX restores the LPS-induced impairments in autophagic flux, attenuates PARP cleavage and alters molecules of the cholinergic system in the spleen. Furthermore, DEX alters and prevents LPS-induced miRNA expression changes in the spleen and brain along with LPS.
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Affiliation(s)
- Widuri Kho
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Clarissa von Haefen
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Nadine Paeschke
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Fatme Nasser
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Stefanie Endesfelder
- Department of Neonatology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Marco Sifringer
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Adrián González-López
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany ,CIBER-Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Nadine Lanzke
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Claudia D. Spies
- Department of Anesthesiology and Operative Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
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7
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Guo M, Bakhoda A, Gao ZG, Ramsey JM, Li Y, O’Conor KA, Kelleher AC, Eisenberg SM, Kang Y, Yan X, Javdan C, Fowler JS, Rice KC, Hooker JM, Jacobson KA, Kim SW, Volkow ND. Discovery of Highly Potent Adenosine A 1 Receptor Agonists: Targeting Positron Emission Tomography Probes. ACS Chem Neurosci 2021; 12:3410-3417. [PMID: 34469110 DOI: 10.1021/acschemneuro.1c00397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Adenosine receptor (AR) radiotracers for positron emission tomography (PET) have provided knowledge on the in vivo biodistribution of ARs in the central nervous system (CNS), which is of therapeutic interest for various neuropsychiatric disorders. Additionally, radioligands that can image changes in endogenous adenosine levels in different physiological and pathological conditions are still lacking. The binding of known antagonist adenosine A1 receptor (A1R) radiotracer, [11C]MDPX, failed to be inhibited by elevated endogenous adenosine in a rodent PET study. Since most of the known AR PET radiotracers were antagonists, we propose that an A1R agonist radioligand may possess higher sensitivity to measure changes in endogenous adenosine concentration. Herein, we report our latest findings toward the development of a full agonist adenosine A1 radioligand for PET. Based on a 3,5-dicyanopyridine template, 16 new derivatives were designed and synthesized to optimize both binding affinity and functional activity, resulting in two full agonists (compounds 27 and 29) with single-digit nanomolar affinities and good subtype selectivity (A1/A2A selectivity of ∼1000-fold for compound 27 and 29-fold for compound 29). Rapid O-[11C]methylation provided [11C]27 and [11C]29 in high radiochemical yields and radiochemical purity. However, subsequent brain PET imaging in rodents showed poor brain permeability for both radioligands. An in vivo PET study using knockout mice for MDR 1a/a, BCRP, and MRP1 indicated that these compounds might be substrates for brain efflux pumps. In addition, in silico evaluation using multiparameter optimization identified high molecular weight and high polar surface area as the main molecular descriptors responsible for low brain penetration. These results will provide further insight toward development of full agonist adenosine A1 radioligands and also highly potent CNS A1AR drugs.
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Affiliation(s)
- Min Guo
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Abolghasem Bakhoda
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Zhan-Guo Gao
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810, United States
| | - Joseph M. Ramsey
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Yang Li
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Kelly A. O’Conor
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Andrew C. Kelleher
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Seth M. Eisenberg
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Yeona Kang
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
- Department of Mathematics, Howard University, Washington, D.C. 20059, United States
| | - Xuefeng Yan
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Cameron Javdan
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Joanna S. Fowler
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Kenner C. Rice
- Drug Design and Synthesis Section, National Institute on Drug Abuse, National Institutes of Health, Rockville, Maryland 20850, United States
| | - Jacob M. Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Kenneth A. Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0810, United States
| | - Sung Won Kim
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
| | - Nora D. Volkow
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
- National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland 20892-1013, United States
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8
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Inkster JAH, Sromek AW, Akurathi V, Neumeyer JL, Packard AB. The Non-Anhydrous, Minimally Basic Synthesis of the Dopamine D 2 Agonist [18F]MCL-524. CHEMISTRY (BASEL, SWITZERLAND) 2021; 3:1047-1056. [PMID: 37830058 PMCID: PMC10569134 DOI: 10.3390/chemistry3030075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
The dopamine D2 agonist MCL-524 is selective for the D2 receptor in the high-affinity state (D2high), and, therefore, the PET analogue, [18F]MCL-524, may facilitate the elucidation of the role of D2high in disorders such as schizophrenia. However, the previously reported synthesis of [18F]MCL-524 proved difficult to replicate and was lacking experimental details. We therefore developed a new synthesis of [18F]MCL-524 using a "non-anhydrous, minimally basic" (NAMB) approach. In this method, [18F]F- is eluted from a small (10-12 mg) trap-and-release column with tetraethylammonium tosylate (2.37 mg) in 7:3 MeCN:H2O (0.1 mL), rather than the basic carbonate or bicarbonate solution that is most often used for [18F]F- recovery. The tosylated precursor (1 mg) in 0.9 mL anhydrous acetonitrile was added directly to the eluate, without azeotropic drying, and the solution was heated (150 °C/15 min). The catechol was then deprotected with the Lewis acid In(OTf)3 (10 equiv.; 150 °C/20 min). In contrast to deprotection with protic acids, Lewis-acid-based deprotection facilitated the efficient removal of byproducts by HPLC and eliminated the need for SPE extraction prior to HPLC purification. Using the NAMB approach, [18F]MCL-524 was obtained in 5-9% RCY (decay-corrected, n = 3), confirming the utility of this improved method for the multistep synthesis of [18F]MCL-524 and suggesting that it may applicable to the synthesis of other 18F-labeled radiotracers.
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Affiliation(s)
- James A. H. Inkster
- Division of Nuclear Medicine and Molecular Imaging, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115, USA
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
| | - Anna W. Sromek
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
- Division of Basic Neuroscience, McLean Hospital, 115 Mill St., Belmont, MA 02478, USA
| | - Vamsidhar Akurathi
- Division of Nuclear Medicine and Molecular Imaging, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115, USA
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
| | - John L. Neumeyer
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
- Division of Basic Neuroscience, McLean Hospital, 115 Mill St., Belmont, MA 02478, USA
| | - Alan B. Packard
- Division of Nuclear Medicine and Molecular Imaging, Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115, USA
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
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9
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Vidal B, Levigoureux E, Chaib S, Bouillot C, Billard T, Newman-Tancredi A, Zimmer L. Different Alterations of Agonist and Antagonist Binding to 5-HT1A Receptor in a Rat Model of Parkinson’s Disease and Levodopa-Induced Dyskinesia: A MicroPET Study. JOURNAL OF PARKINSONS DISEASE 2021; 11:1257-1269. [DOI: 10.3233/jpd-212580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Background: The gold-standard treatment for Parkinson’s disease is L-DOPA, which in the long term often leads to levodopa-induced dyskinesia. Serotonergic neurons are partially responsible for this, by converting L-DOPA into dopamine leading to its uncontrolled release as a “false neurotransmitter”. The stimulation of 5-HT1A receptors can reduce involuntary movements but this mechanism is poorly understood. Objective: This study aimed to investigate the functionality of 5-HT1A receptors using positron emission tomography in hemiparkinsonian rats with or without dyskinesia induced by 3-weeks daily treatment with L-DOPA. Imaging sessions were performed “off” L-DOPA. Methods: Each rat underwent a positron emission tomography scan with [18F]F13640, a 5-HT1AR agonist which labels receptors in a high affinity state for agonists, or with [18F]MPPF, a 5-HT1AR antagonist which labels all the receptors. Results: There were decreases of [18F]MPPF binding in hemiparkinsonian rats in cortical areas. In dyskinetic animals, changes were slighter but also found in other regions. In hemiparkinsonian rats, [18F]F13640 uptake was decreased bilaterally in the globus pallidus and thalamus. On the non-lesioned side, binding was increased in the insula, the hippocampus and the amygdala. In dyskinetic animals, [18F]F13640 binding was strongly increased in cortical and limbic areas, especially in the non-lesioned side. Conclusion: These data suggest that agonist and antagonist 5-HT1A receptor-binding sites are differently modified in Parkinson’s disease and levodopa-induced dyskinesia. In particular, these observations suggest a substantial involvement of the functional state of 5-HT1AR in levodopa-induced dyskinesia and emphasize the need to characterize this state using agonist radiotracers in physiological and pathological conditions.
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Affiliation(s)
- Benjamin Vidal
- Lyon Neuroscience Research Center, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSERM, Lyon, France
| | - Elise Levigoureux
- Lyon Neuroscience Research Center, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSERM, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | - Sarah Chaib
- Lyon Neuroscience Research Center, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSERM, Lyon, France
- Hospices Civils de Lyon, Lyon, France
| | | | - Thierry Billard
- CERMEP-Imaging Platform, Bron, France
- Institute of Chemistry and Biochemistry, Université de Lyon, CNRS, Villeurbanne, France
| | | | - Luc Zimmer
- Lyon Neuroscience Research Center, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, INSERM, Lyon, France
- Hospices Civils de Lyon, Lyon, France
- CERMEP-Imaging Platform, Bron, France
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10
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Matthee C, Terre'Blanche G, Legoabe LJ, Janse van Rensburg HD. Exploration of chalcones and related heterocycle compounds as ligands of adenosine receptors: therapeutics development. Mol Divers 2021; 26:1779-1821. [PMID: 34176057 DOI: 10.1007/s11030-021-10257-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/15/2021] [Indexed: 12/20/2022]
Abstract
Adenosine receptors (ARs) are ubiquitously distributed throughout the mammalian body where they are involved in an extensive list of physiological and pathological processes that scientists have only begun to decipher. Resultantly, AR agonists and antagonists have been the focus of multiple drug design and development programmes within the past few decades. Considered to be a privileged scaffold in medicinal chemistry, the chalcone framework has attracted a substantial amount of interest in this regard. Due to the potential liabilities associated with its structure, however, it has become necessary to explore other potentially promising compounds, such as heterocycles, which have successfully been obtained from chalcone precursors in the past. This review aims to summarise the emerging therapeutic importance of adenosine receptors and their ligands, especially in the central nervous system (CNS), while highlighting chalcone and heterocyclic derivatives as promising AR ligand lead compounds.
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Affiliation(s)
- Chrisna Matthee
- Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, North West, South Africa
| | - Gisella Terre'Blanche
- Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, North West, South Africa.,Centre of Excellence for Pharmaceutical Sciences, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, North West, South Africa
| | - Lesetja J Legoabe
- Centre of Excellence for Pharmaceutical Sciences, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, North West, South Africa
| | - Helena D Janse van Rensburg
- Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, North West, South Africa.
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11
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Opposite alterations of 5-HT 2A receptor brain density in subjects with schizophrenia: relevance of radiotracers pharmacological profile. Transl Psychiatry 2021; 11:302. [PMID: 34016955 PMCID: PMC8137947 DOI: 10.1038/s41398-021-01430-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 04/26/2021] [Accepted: 05/05/2021] [Indexed: 02/04/2023] Open
Abstract
The status of serotonin 5-HT2A receptors (5-HT2ARs) in schizophrenia has been controversial. In vivo positron emission tomography neuroimaging and in vitro post-mortem binding studies have reported conflicting results about 5-HT2AR density. Radiotracers bind different receptor conformations depending on their agonist, antagonist or inverse agonist properties. This study investigates 5-HT2AR density in the post-mortem prefrontal cortex from subjects with schizophrenia and controls using three radiotracers with a different pharmacological profile. The specific binding parameters of the inverse agonist [18F]altanserin, the agonist [3H]lysergic acid diethylamide (LSD) and the antagonist [3H]MDL100907 to brain cortex membranes from 20 subjects with schizophrenia and 20 individually matched controls were evaluated under similar methodological conditions. Ten schizophrenia subjects were antipsychotic-free at death. Saturation curve analyses were performed by non-linear regression to obtain a maximal density of binding sites (Bmax) and the affinity of the respective radiotracers (Kd). In schizophrenia subjects, 5-HT2AR density was decreased when quantified by [18F]altanserin binding, whereas increased when evaluated by [3H]LSD binding. However, [3H]MDL100907 binding was unaltered. A slight loss of affinity (higher Kd) was observed exclusively in [3H]LSD binding. The findings were more evident in antipsychotic-free subjects than in antipsychotic-treated subjects. In conclusion, a higher proportion of the 5-HT2AR-active functional conformation, which is rather identified by agonist radiotracers, was observed in schizophrenia patients. A consequent reduction of the inactive 5-HT2AR conformation, which is preferentially identified by inverse agonist radiotracers, was also obtained. Antagonist radiotracers do not distinguish between molecular conformations of the receptor, and accordingly, the absence of changes was shown. These results are compatible with the proposed increased functional activity of brain cortical 5-HT2ARs in schizophrenia.
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12
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Kilbourn MR. 11C- and 18F-Radiotracers for In Vivo Imaging of the Dopamine System: Past, Present and Future. Biomedicines 2021; 9:108. [PMID: 33499179 PMCID: PMC7912183 DOI: 10.3390/biomedicines9020108] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/17/2021] [Accepted: 01/19/2021] [Indexed: 12/17/2022] Open
Abstract
The applications of positron emission tomography (PET) imaging to study brain biochemistry, and in particular the aspects of dopamine neurotransmission, have grown significantly over the 40 years since the first successful in vivo imaging studies in humans. In vivo PET imaging of dopaminergic functions of the central nervous system (CNS) including dopamine synthesis, vesicular storage, synaptic release and receptor binding, and reuptake processes, are now routinely used for studies in neurology, psychiatry, drug abuse and addiction, and drug development. Underlying these advances in PET imaging has been the development of the unique radiotracers labeled with positron-emitting radionuclides such as carbon-11 and fluorine-18. This review focuses on a selection of the more accepted and utilized PET radiotracers currently available, with a look at their past, present and future.
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Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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13
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Raval NR, Johansen A, Donovan LL, Ros NF, Ozenne B, Hansen HD, Knudsen GM. A Single Dose of Psilocybin Increases Synaptic Density and Decreases 5-HT 2A Receptor Density in the Pig Brain. Int J Mol Sci 2021; 22:E835. [PMID: 33467676 PMCID: PMC7830000 DOI: 10.3390/ijms22020835] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 02/06/2023] Open
Abstract
A single dose of psilocybin, a psychedelic and serotonin 2A receptor (5-HT2AR) agonist, may be associated with antidepressant effects. The mechanism behind its antidepressive action is unknown but could be linked to increased synaptogenesis and down-regulation of cerebral 5-HT2AR. Here, we investigate if a single psychedelic dose of psilocybin changes synaptic vesicle protein 2A (SV2A) and 5-HT2AR density in the pig brain. Twenty-four awake pigs received either 0.08 mg/kg psilocybin or saline intravenously. Twelve pigs (n = 6/intervention) were euthanized one day post-injection, while the remaining twelve pigs were euthanized seven days post-injection (n = 6/intervention). We performed autoradiography on hippocampus and prefrontal cortex (PFC) sections with [3H]UCB-J (SV2A), [3H]MDL100907 (5-HT2AR antagonist) and [3H]Cimbi-36 (5-HT2AR agonist). One day post psilocybin injection, we observed 4.42% higher hippocampal SV2A density and lowered hippocampal and PFC 5-HT2AR density (-15.21% to -50.19%). These differences were statistically significant in the hippocampus for all radioligands and in the PFC for [3H]Cimbi-36 only. Seven days post-intervention, there was still significantly higher SV2A density in the hippocampus (+9.24%) and the PFC (+6.10%), whereas there were no longer any differences in 5-HT2AR density. Our findings suggest that psilocybin causes increased persistent synaptogenesis and an acute decrease in 5-HT2AR density, which may play a role in psilocybin's antidepressive effects.
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Affiliation(s)
- Nakul Ravi Raval
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Annette Johansen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Lene Lundgaard Donovan
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Nídia Fernandez Ros
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
| | - Brice Ozenne
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Department of Public Health, Section of Biostatistics, Faculty of Health and Medical Sciences, University of Copenhagen, 1014 Copenhagen, Denmark
| | - Hanne Demant Hansen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Gitte Moos Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, 2100 Copenhagen, Denmark; (N.R.R.); (A.J.); (L.L.D.); (N.F.R.); (B.O.); (H.D.H.)
- Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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14
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Razakarivony O, Newman-Tancredi A, Zimmer L. Towards in vivo imaging of functionally active 5-HT 1A receptors in schizophrenia: concepts and challenges. Transl Psychiatry 2021; 11:22. [PMID: 33414418 PMCID: PMC7791062 DOI: 10.1038/s41398-020-01119-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 12/18/2022] Open
Abstract
The serotonin 5-HT1A receptor has attracted wide attention as a target for treatment of psychiatric disorders. Although this receptor is important in the pharmacological mechanisms of action of new-generation antipsychotics, its characterization remains incomplete. Studies based on in vitro molecular imaging on brain tissue by autoradiography, and more recently in vivo PET imaging, have not yielded clear results, in particular due to the limitations of current 5-HT1A radiotracers, which lack specificity and/or bind to all 5-HT1A receptors, regardless of their functional status. The new concept of PET neuroimaging of functionally active G-protein-coupled receptors makes it possible to revisit PET brain exploration by enabling new research paradigms. For the 5-HT1A receptor it is now possible to use [18F]-F13640, a 5-HT1A receptor radioligand with high efficacy agonist properties, to specifically visualize and quantify functionally active receptors, and to relate this information to subjects' pathophysiological or pharmacological state. We therefore propose imaging protocols to follow changes in the pattern of functional 5-HT1A receptors in relation to mood deficits or cognitive processes. This could allow improved discrimination of different schizophrenia phenotypes and greater understanding of the basis of therapeutic responses to antipsychotic drugs. Finally, as well as targeting functionally active receptors to gain insights into the role of 5-HT1A receptors, the concept can also be extended to the study of other receptors involved in the pathophysiology or therapy of psychiatric disorders.
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Affiliation(s)
- Oriane Razakarivony
- grid.25697.3f0000 0001 2172 4233Université de Lyon, Lyon Neuroscience Research Center, INSERM, CNRS, Lyon, France ,grid.413852.90000 0001 2163 3825Hospices Civils de Lyon, Lyon, France
| | | | - Luc Zimmer
- Université de Lyon, Lyon Neuroscience Research Center, INSERM, CNRS, Lyon, France. .,Hospices Civils de Lyon, Lyon, France. .,CERMEP-Imagerie du Vivant, Bron, France. .,French National Institute for Nuclear Science and Technology, CEA Saclay, Gif-sur-Yvette, France.
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15
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Naganawa M, Nabulsi N, Henry S, Matuskey D, Lin SF, Slieker L, Schwarz AJ, Kant N, Jesudason C, Ruley K, Navarro A, Gao H, Ropchan J, Labaree D, Carson RE, Huang Y. First-in-Human Assessment of 11C-LSN3172176, an M1 Muscarinic Acetylcholine Receptor PET Radiotracer. J Nucl Med 2020; 62:553-560. [PMID: 32859711 DOI: 10.2967/jnumed.120.246967] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 07/09/2020] [Indexed: 01/25/2023] Open
Abstract
This was a first-in-human study of the PET radiotracer 11C-LSN3172176 for the muscarinic acetylcholine receptor subtype M1. The objectives of the study were to determine the appropriate kinetic model to quantify binding of the tracer to M1 receptors, and the reliability of the chosen quantification method. Methods: Six healthy subjects completed the test-retest protocol, and 5 healthy subjects completed the baseline-scopolamine blocking protocol. Multiple modeling methods were applied to calculate total distribution volume (V T) and nondisplaceable binding potential (BP ND) in various brain regions. The reference region was selected from the blocking study. The occupancy plot was applied to compute receptor occupancy by scopolamine and nondisplaceable distribution volume. Results: Tracer uptake was highest in the striatum, followed by neocortical regions and white matter, and lowest in the cerebellum. Regional time-activity curves were fitted well by all models. The 2-tissue-compartment (2TC) model fits were good, but the 2TC parameters often could not be reliably estimated. Because V T correlated well between the 2TC and 1-tissue-compartment (1TC) models after exclusion of unreliable estimates, the 1TC model was chosen as the most appropriate. The cerebellum showed the lowest V T, consistent with preclinical studies showing little to no specific binding in the region. Further, cerebellar V T did not change between baseline and blocking scans, indicating that the cerebellum is a suitable reference region. The simplified reference tissue model (SRTM) slightly underestimated 1TC BP ND, and the simplified reference tissue model 2 (SRTM2) improved BP ND estimation. An 80-min scan was sufficient to quantify V T and BP ND The test-retest study showed excellent absolute test-retest variability for 1TC V T (≤5%) and BP ND (≤10%). In the baseline and blocking studies, occupancy values were lower in the striatum than in nonstriatal regions, as may be attributed to differences in regional acetylcholine concentrations. Conclusion: The 1TC and SRTM2 models are appropriate for quantitative analysis of 11C-LSN3172176 imaging data. 11C-LSN3172176 displayed excellent test-retest reproducibility and is a highly promising ligand to quantify M1 receptors in the human brain.
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Affiliation(s)
- Mika Naganawa
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Nabeel Nabulsi
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Shannan Henry
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - David Matuskey
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Shu-Fei Lin
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | | | | | - Nancy Kant
- Eli Lilly and Company, Indianapolis, Indiana
| | | | - Kevin Ruley
- Eli Lilly and Company, Indianapolis, Indiana
| | | | - Hong Gao
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Jim Ropchan
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - David Labaree
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Richard E Carson
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
| | - Yiyun Huang
- PET Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut; and
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16
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Naganawa M, Li S, Nabulsi N, Lin SF, Labaree D, Ropchan J, Gao H, Mei M, Henry S, Matuskey D, Carson RE, Huang Y. Kinetic Modeling and Test-Retest Reproducibility of 11C-EKAP and 11C-FEKAP, Novel Agonist Radiotracers for PET Imaging of the κ-Opioid Receptor in Humans. J Nucl Med 2020; 61:1636-1642. [PMID: 32169917 DOI: 10.2967/jnumed.119.227694] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/09/2020] [Indexed: 12/13/2022] Open
Abstract
The κ-opioid receptor (KOR) is implicated in various neuropsychiatric disorders. We previously evaluated an agonist tracer, 11C-GR103545, for PET imaging of KOR in humans. Although 11C-GR103545 showed high brain uptake, good binding specificity, and selectivity for KOR, it displayed slow kinetics and relatively large test-retest variability of total distribution volume (V T) estimates (15%). Therefore, we set out to develop 2 novel KOR agonist radiotracers, 11C-EKAP and 11C-FEKAP. In nonhuman primates, both tracers exhibited faster kinetics than 11C-GR103545 and comparable binding parameters to 11C-GR103545. The aim of this study was to assess their kinetic and binding properties in humans. Methods: Six healthy subjects underwent 120-min test-retest PET scans with both 11C-EKAP and 11C-FEKAP. Metabolite-corrected arterial input functions were measured. Regional time-activity curves were generated for 14 regions of interest. One-tissue-compartment and 2-tissue-compartment (2TC) models and the multilinear analysis-1 (MA1) method were applied to the regional time-activity curves to calculate V T The time stability of V T and test-retest reproducibility were evaluated. Levels of specific binding, as measured by the nondisplaceable binding potential (BP ND) for the 3 tracers (11C-EKAP, 11C-FEKAP, and 11C-GR103545), were compared using a graphical method. Results: For both tracers, regional time-activity curves were fitted well with the 2TC model and MA1 method (t* = 20 min) but not with the 1-tissue-compartment model. Given the unreliably estimated parameters in several fits with the 2TC model and a good V T match between MA1 and 2TC, MA1 was chosen as the appropriate model for both tracers. Mean MA1 V T was highest for 11C-GR103545, followed by 11C-EKAP and then 11C-FEKAP. The minimum scan time for stable V T measurement was 90 and 110 min for 11C-EKAP and 11C-FEKAP, respectively, compared with 140 min for 11C-GR103545. The mean absolute test-retest variability in MA1 V T estimates was 7% and 18% for 11C-EKAP and 11C-FEKAP, respectively. BP ND levels were similar for 11C-FEKAP and 11C-GR103545 but were about 25% lower for 11C-EKAP. Conclusion: The 2 novel KOR agonist tracers showed faster tissue kinetics than 11C-GR103545. Even with a slightly lower BP ND, 11C-EKAP is judged to be a better tracer for imaging and quantification of KOR in humans, on the basis of the shorter minimum scan time and the excellent test-retest reproducibility of regional V T.
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Affiliation(s)
- Mika Naganawa
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Songye Li
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Nabeel Nabulsi
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Shu-Fei Lin
- Yale PET Center, Yale University, New Haven, Connecticut
| | - David Labaree
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Jim Ropchan
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Hong Gao
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Michael Mei
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Shannan Henry
- Yale PET Center, Yale University, New Haven, Connecticut
| | - David Matuskey
- Yale PET Center, Yale University, New Haven, Connecticut
| | | | - Yiyun Huang
- Yale PET Center, Yale University, New Haven, Connecticut
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17
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Lindberg A, Arakawa R, Nogami T, Nag S, Schou M, Elmore CS, Farde L, Pike VW, Halldin C. Potential for imaging the high-affinity state of the 5-HT 1B receptor: a comparison of three PET radioligands with differing intrinsic activity. EJNMMI Res 2019; 9:100. [PMID: 31754940 PMCID: PMC6872687 DOI: 10.1186/s13550-019-0570-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/01/2019] [Indexed: 11/19/2022] Open
Abstract
Background Over the last decade, a few radioligands have been developed for PET imaging of brain 5-HT1B receptors. The 5-HT1B receptor is a G-protein-coupled receptor (GPCR) that exists in two different agonist affinity states. An agonist ligand is expected to be more sensitive towards competition from another agonist, such as endogenous 5-HT, than an antagonist ligand. It is of interest to know whether the intrinsic activity of a PET radioligand for the 5-HT1B receptor impacts on its ability to detect changes in endogenous synaptic 5-HT density. Three high-affinity 11C-labeled 5-HT1B PET radioligands with differing intrinsic activity were applied to PET measurements in cynomolgus monkey to evaluate their sensitivity to be displaced within the brain by endogenous 5-HT. For these experiments, fenfluramine was pre-administered at two different doses (1.0 and 5.0 mg/kg, i.v.) to induce synaptic 5-HT release. Results A dose-dependent response to fenfluramine was detected for all three radioligands. At the highest dose of fenfluramine (5.0 mg/kg, i.v.), reductions in specific binding in the occipital cortex increased with radioligand agonist efficacy, reaching 61% for [11C]3. The most antagonistic radioligand showed the lowest reduction in specific binding. Conclusions Three 5-HT1B PET radioligands were identified with differing intrinsic activity that could be used in imaging high- and low-affinity states of 5-HT1B receptors using PET. From this limited study, radioligand sensitivity to endogenous 5-HT appears to depend on agonist efficacy. More extensive studies are required to substantiate this suggestion.
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Affiliation(s)
- Anton Lindberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden. .,Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892-1003, USA.
| | - Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Tsuyoshi Nogami
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
| | - Magnus Schou
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden.,PET Science Centre, Precision Medicine and Genomics, R&D, AstraZeneca, SE-17176, Stockholm, Sweden
| | - Charles S Elmore
- Isotope Chemistry, Early Chemical Development, Pharmaceutical Sciences R&D, AstraZeneca, SE-43250, Göteborg, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden.,PET Science Centre, Precision Medicine and Genomics, R&D, AstraZeneca, SE-17176, Stockholm, Sweden
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892-1003, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, SE-17176, Stockholm, Sweden
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18
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Colom M, Vidal B, Zimmer L. Is There a Role for GPCR Agonist Radiotracers in PET Neuroimaging? Front Mol Neurosci 2019; 12:255. [PMID: 31680859 PMCID: PMC6813225 DOI: 10.3389/fnmol.2019.00255] [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: 07/25/2019] [Accepted: 10/02/2019] [Indexed: 12/30/2022] Open
Abstract
Positron emission tomography (PET) is a molecular imaging modality that enables in vivo exploration of metabolic processes and especially the pharmacology of neuroreceptors. G protein-coupled receptors (GPCRs) play an important role in numerous pathophysiologic disorders of the central nervous system. Thus, they are targets of choice in PET imaging to bring proof concept of change in density in pathological conditions or in pharmacological challenge. At present, most radiotracers are antagonist ligands. In vitro data suggest that properties differ between GPCR agonists and antagonists: antagonists bind to receptors with a single affinity, whereas agonists are characterized by two different affinities: high affinity for receptors that undergo functional coupling to G-proteins, and low affinity for those that are not coupled. In this context, agonist radiotracers may be useful tools to give functional images of GPCRs in the brain, with high sensitivity to neurotransmitter release. Here, we review all existing PET radiotracers used from animals to humans and their role for understanding the ligand-receptor paradigm of GPCR in comparison with corresponding antagonist radiotracers.
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Affiliation(s)
- Matthieu Colom
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France
| | - Benjamin Vidal
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France
| | - Luc Zimmer
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France.,Institut National des Sciences et Techniques Nucléaires, CEA Saclay, Gif-sur-Yvette, France
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19
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Human biodistribution and radiation dosimetry of the 5-HT 2A receptor agonist Cimbi-36 labeled with carbon-11 in two positions. EJNMMI Res 2019; 9:71. [PMID: 31367837 PMCID: PMC6669221 DOI: 10.1186/s13550-019-0527-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/20/2019] [Indexed: 12/17/2022] Open
Abstract
Background Cimbi-36 can be 11C-labeled to form an agonist radioligand used for positron emission tomography (PET) imaging of the 5-HT2A receptor in the brain. In its non-labeled form (25B-NBOMe), it is used as a recreational drug that can lead to severe adverse effects, in some cases, with fatal outcome. We investigated human biodistribution and radiation dosimetry of the radioligand with two different radiolabeling positions. Seven healthy volunteers underwent dynamic 120-min whole-body PET scans (injection of 581 ± 16 MBq, n = 5 for 11C-Cimbi-36; 593 ± 14 MBq, n = 2 for 11C-Cimbi-36_5). Time-integrated activity coefficients (TIACs) from time-activity curves (TACs) of selected organs were used as input into the OLINDA/EXM software to obtain dosimetry information for both 11C-labeling positions of Cimbi-36. Results The effective dose was only slightly higher for 11C-Cimbi-36 (5.5 μSv/MBq) than for 11C-Cimbi-36_5 (5.3 μSv/MBq). Standard uptake value (SUV) curves showed higher uptake of 11C-Cimbi-36 in the pancreas, small intestines, liver, kidney, gallbladder, and urinary bladder compared with 11C-Cimbi-36_5, reflecting differences in radiometabolism for the two radioligands. Variability in uptake in excretory organs for 11C-Cimbi-36 points to inter-individual differences with regard to metabolic rate and route. Surprisingly, moderate uptake was found in brown adipose tissue (BAT) in four subjects, possibly representing specific 5-HT2A/2C receptor binding. Conclusion The low effective dose of 5.5 μSv/MBq allows for the injection of up to 1.8 GBq for healthy volunteers per study (equivalent to 3 scans if injecting 600 MBq) and still stay below the international guidelines of 10 mSv, making 11C-Cimbi-36 eligible for studies involving a series of PET scans in a single subject. The biodistribution of Cimbi-36 (and its metabolites) may also help to shed light on the toxic effects of 25B-NBOMe when used in pharmacological doses in recreational settings. Electronic supplementary material The online version of this article (10.1186/s13550-019-0527-4) contains supplementary material, which is available to authorized users.
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20
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Lever JR, Fergason-Cantrell EA, Carmack TL, Watkinson LD, Gallazzi F. Design, synthesis and evaluation of 111In labeled DOTA-conjugated tetrapeptides having high affinity and selectivity for mu opioid receptors. Nucl Med Biol 2019; 70:53-66. [PMID: 30933866 DOI: 10.1016/j.nucmedbio.2019.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 02/10/2019] [Accepted: 02/17/2019] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Peripheral mu (μ) opioid receptors are implicated in pain, bowel dysfunction and the progression of certain cancers. In an effort to identify radioligands well suited for imaging these peripheral sites, we have prepared and evaluated four hydrophilic 111In labeled DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) conjugated μ tetrapeptides. METHODS Peptides were prepared by solid-phase techniques, using orthogonal strategies to achieve branching to DOTA, and then characterized by HPLC, mass spectroscopy and amino acid analysis. Scaffolds included novel peptide H-Dmt-D-Ala-Phe-Orn-NH2 (DAPO), where Dmt = 2',6'-dimethyltyrosine, and known peptide H-Dmt-D-Arg-Phe-Lys-NH2 ([Dmt1]DALDA). Constructs had DOTA conjugation at the Orn4 or Lys4 side chains, or to the C-terminal through a hexanoic acid-lysine linker. Indium(III) complexation and 111In radiolabeling were accomplished by standard methods. Protein binding and Log D7.4 were determined. Binding and pharmacological profiles were obtained in vitro. Biodistribution and radiometabolite studies were conducted using male CD-1 mice. RESULTS All four indium(III)-DOTA conjugates derived from DAPO and [Dmt1]DALDA showed good selectivity and subnanomolar affinity for μ opioid receptors. One radioligand, H-Dmt-D-Ala-Phe-Orn(δ-[111In]In-DOTA)-NH2, showed 25% specific binding in vivo to μ sites in mouse gut. Notably, this was the least polar of the series, and also showed low sensitivity to modulation of binding by sodium ions. All radioligands showed high kidney uptake of radiometabolites. CONCLUSIONS Visualizing peripheral μ opioid receptors using 111In labeled DOTA-conjugated tetrapeptides appears feasible, but structural modifications to enhance specific binding and metabolic stability, as well as to reduce kidney uptake, will be required. ADVANCES IN KNOWLEDGE This study shows in vivo labeling of peripheral μ opioid receptors by a tetrapeptide radioligand, and provides information that should prove useful in the design of peptide radioligands having optimal properties.
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Affiliation(s)
- John R Lever
- Department of Radiology, University of Missouri, Columbia, MO 65212, USA; Radiopharmaceutical Sciences Institute, University of Missouri, Columbia, MO 65211, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA.
| | - Emily A Fergason-Cantrell
- Department of Radiology, University of Missouri, Columbia, MO 65212, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA
| | - Terry L Carmack
- Radiopharmaceutical Sciences Institute, University of Missouri, Columbia, MO 65211, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA
| | - Lisa D Watkinson
- Radiopharmaceutical Sciences Institute, University of Missouri, Columbia, MO 65211, USA; Harry S. Truman Memorial Veterans' Hospital, Columbia, MO 65201, USA
| | - Fabio Gallazzi
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA; Molecular Interaction Core, University of Missouri, Columbia, MO 65211, USA
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Shalgunov V, van Waarde A, Booij J, Michel MC, Dierckx RAJO, Elsinga PH. Hunting for the high-affinity state of G-protein-coupled receptors with agonist tracers: Theoretical and practical considerations for positron emission tomography imaging. Med Res Rev 2018; 39:1014-1052. [PMID: 30450619 PMCID: PMC6587759 DOI: 10.1002/med.21552] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/02/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022]
Abstract
The concept of the high‐affinity state postulates that a certain subset of G‐protein‐coupled receptors is primarily responsible for receptor signaling in the living brain. Assessing the abundance of this subset is thus potentially highly relevant for studies concerning the responses of neurotransmission to pharmacological or physiological stimuli and the dysregulation of neurotransmission in neurological or psychiatric disorders. The high‐affinity state is preferentially recognized by agonists in vitro. For this reason, agonist tracers have been developed as tools for the noninvasive imaging of the high‐affinity state with positron emission tomography (PET). This review provides an overview of agonist tracers that have been developed for PET imaging of the brain, and the experimental paradigms that have been developed for the estimation of the relative abundance of receptors configured in the high‐affinity state. Agonist tracers appear to be more sensitive to endogenous neurotransmitter challenge than antagonists, as was originally expected. However, other expectations regarding agonist tracers have not been fulfilled. Potential reasons for difficulties in detecting the high‐affinity state in vivo are discussed.
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Affiliation(s)
- Vladimir Shalgunov
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.,Department of Nuclear Medicine, Ghent University, University Hospital, Ghent, Belgium
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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