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Pitoy M, Gauthier L, Debatisse J, Maulavé J, Météreau E, Beaudoin M, Portier K, Sgambato V, Billard T, Zimmer L, Lancelot S, Tremblay L. SB-258585 reduces food motivation while blocking 5-HT 6 receptors in the non-human primate striatum. Prog Neuropsychopharmacol Biol Psychiatry 2024; 131:110970. [PMID: 38354894 DOI: 10.1016/j.pnpbp.2024.110970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 02/09/2024] [Accepted: 02/11/2024] [Indexed: 02/16/2024]
Abstract
The interest in new 5-HT₆ agents stems from their ability to modulate cognition processing, food motivation and anxiety-like behaviors. While these findings come primarily from rodent studies, no studies on primates have been published. Furthermore, our understanding of where and how they act in the brain remains limited. Although the striatum is involved in all of these processes and expresses the highest levels of 5-HT₆ receptors, few studies have focused on it. We thus hypothesized that 5-HT6 receptor blockade would influence food motivation and modulate behavioral expression in non-human primates through striatal 5-HT6 receptors. This study thus aimed to determine the effects of acute administration of the SB-258585 selective 5-HT6 receptor antagonist on the feeding motivation and behaviors of six male macaques. Additionally, we investigated potential 5-HT6 targets using PET imaging to measure 5-HT6 receptor occupancy throughout the brain and striatal subregions. We used a food-choice task paired with spontaneous behavioral observations, checking 5-HT6 receptor occupancy with the specific PET imaging [18F]2FNQ1P radioligand. We demonstrated, for the first time in non-human primates, that modulation of 5-HT6 transmission, most likely through the striatum (the putamen and caudate nucleus), significantly reduces food motivation while exhibiting variable, weaker effects on behavior. While these results are consistent with the literature showing a decrease in food intake in rodents and proposing that 5-HT6 receptor antagonists can be used in obesity treatment, they question the antagonists' anxiolytic potential.
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Affiliation(s)
- Mathilde Pitoy
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France; Hospices Civils de Lyon, 3 Quai des Célestins, 69002 Lyon, France.
| | - Lisa Gauthier
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France
| | - Justine Debatisse
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Centre de Recherche en Neurosciences de Lyon, CNRS UMR5292, INSERM U1028, Lyon, France
| | - Julie Maulavé
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France
| | - Elise Météreau
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Hospices Civils de Lyon, 3 Quai des Célestins, 69002 Lyon, France
| | - Maude Beaudoin
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France
| | - Karine Portier
- Université de Lyon, VetAgro Sup, CREFAC, 69280 Marcy l'Etoile, France; UCBL, CNRS, INSERM, CRNL U1028 UMR5292, Trajectoire, Lyon, 69500 Bron, France
| | - Véronique Sgambato
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France
| | | | - Luc Zimmer
- Université Claude-Bernard Lyon1, 69100 Villeurbanne, France; Hospices Civils de Lyon, 3 Quai des Célestins, 69002 Lyon, France; Centre de Recherche en Neurosciences de Lyon, CNRS UMR5292, INSERM U1028, Lyon, France; CERMEP-Imagerie du Vivant, 59 Bd Pinel, 69677 Bron, France
| | - Sophie Lancelot
- Université Claude-Bernard Lyon1, 69100 Villeurbanne, France; Hospices Civils de Lyon, 3 Quai des Célestins, 69002 Lyon, France; Centre de Recherche en Neurosciences de Lyon, CNRS UMR5292, INSERM U1028, Lyon, France; CERMEP-Imagerie du Vivant, 59 Bd Pinel, 69677 Bron, France
| | - Léon Tremblay
- Institut des Sciences Cognitives Marc Jeannerod, UMR-5229 CNRS, 67 boulevard Pinel, 69675 Bron Cedex, France; Université Claude-Bernard Lyon1, 69100 Villeurbanne, France.
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Zimmer L. Recent applications of positron emission tomographic (PET) imaging in psychiatric drug discovery. Expert Opin Drug Discov 2024; 19:161-172. [PMID: 37948046 DOI: 10.1080/17460441.2023.2278635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023]
Abstract
INTRODUCTION Psychiatry is one of the medical disciplines that suffers most from a lack of innovation in its therapeutic arsenal. Many failures in drug candidate trials can be explained by pharmacological properties that have been poorly assessed upstream, in terms of brain passage, brain target binding and clinical outcomes. Positron emission tomography can provide pharmacokinetic and pharmacodynamic data to help select candidate-molecules for further clinical trials. AREAS COVERED This review aims to explain and discuss the various methods using positron-emitting radiolabeled molecules to trace the cerebral distribution of the drug-candidate or indirectly measure binding to its therapeutic target. More than an exhaustive review of PET studies in psychopharmacology, this article highlights the contributions this technology can make in drug discovery applied to psychiatry. EXPERT OPINION PET neuroimaging is the only technological approach that can, in vivo in humans, measure cerebral delivery of a drug candidate, percentage and duration of target binding, and even the pharmacological effects. PET studies in a small number of subjects in the early stages of the development of a psychotropic drug can therefore provide the pharmacokinetic/pharmacodynamic data required for subsequent clinical evaluation. While PET technology is demanding in terms of radiochemical, radiopharmacological and nuclear medicine expertise, its integration into the development process of new drugs for psychiatry has great added value.
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Affiliation(s)
- Luc Zimmer
- Lyon Neuroscience Research Center, Université Claude Bernard, Lyon, France
- CERMEP, Hospices Civils de Lyon, Lyon, France
- Institut National des Sciences et Technologies Nucléaire, Saclay, France
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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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Courault P, Emery S, Bouvard S, Liger F, Chauveau F, Meyronet D, Fourier A, Billard T, Zimmer L, Lancelot S. Change in Expression of 5-HT6 Receptor at Different Stages of Alzheimer's Disease: A Postmortem Study with the PET Radiopharmaceutical [18F]2FNQ1P. J Alzheimers Dis 2020; 75:1329-1338. [PMID: 32417774 DOI: 10.3233/jad-191278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The 5-HT6 receptor is one of the most recently identified serotonin receptors in the central nervous system. Because of its role in memory and cognitive process, this receptor might be implicated in Alzheimer's disease (AD) and associated disorders. OBJECTIVE The aim of this study was to investigate the binding of [18F]2FNQ1P, a new specific radiotracer of 5-HT6 receptors, and to quantify 5-HT6 receptor density in caudate nucleus in a population of patients with different AD stages. METHODS Patients were classified according to the "ABC" NIA-AA classification. In vitro binding assays were performed in postmortem brain tissue from the healthy control (HC; n = 8) and severe AD ("High"; n = 8) groups. In vitro quantitative autoradiography was performed in human brain tissue (caudate nucleus) from patients with different stages of AD: HC (n = 15), "Low" (n = 18), "Int" (n = 20), and "High" (n = 15). RESULTS In vitro binding assays did not show significant differences for the KD and Bmax parameters between "High" and HC groups. In vitro quantitative autoradiography showed a significant difference between the "High" and HC groups (p = 0.0025). We also showed a progressive diminution in [18F]2FNQ1P specific binding, which parallels 5-HT6 receptors expression, according to increasing AD stage. Significant differences were observed between the HC group and all AD stages combined ("Low", "Intermediate", and "High") (p = 0.011). CONCLUSION This study confirms the interest of investigating the role of 5-HT6 receptors in AD and related disorders. [18F]2FNQ1P demonstrated specific binding to 5-HT6 receptors.
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Affiliation(s)
- Pierre Courault
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France.,Hospices Civils de Lyon (HCL), Lyon, France
| | - Stéphane Emery
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France
| | - Sandrine Bouvard
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France
| | - François Liger
- CERMEP-Imaging platform, Groupement Hospitalier Est, Bron, France
| | - Fabien Chauveau
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France
| | | | - Anthony Fourier
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France.,Hospices Civils de Lyon (HCL), Lyon, France
| | - Thierry Billard
- CERMEP-Imaging platform, Groupement Hospitalier Est, Bron, France.,Institute of Chemistry and Biochemistry (ICBMS), Université de Lyon, CNRS, Villeurbanne, France
| | - Luc Zimmer
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France.,Hospices Civils de Lyon (HCL), Lyon, France.,CERMEP-Imaging platform, Groupement Hospitalier Est, Bron, France.,National Institute for Nuclear Science and Technology (INSTN), CEA, Saclay, France
| | - Sophie Lancelot
- Lyon Neuroscience Research Center (CRNL), Université de Lyon, CNRS, INSERM, Lyon, France.,Hospices Civils de Lyon (HCL), Lyon, France.,CERMEP-Imaging platform, Groupement Hospitalier Est, Bron, France
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Emery S, Fieux S, Vidal B, Courault P, Bouvard S, Tourvieille C, Iecker T, Billard T, Zimmer L, Lancelot S. Preclinical validation of [ 18F]2FNQ1P as a specific PET radiotracer of 5-HT 6 receptors in rat, pig, non-human primate and human brain tissue. Nucl Med Biol 2020; 82-83:57-63. [PMID: 32006785 DOI: 10.1016/j.nucmedbio.2020.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 12/20/2022]
Abstract
INTRODUCTION The aim of this study was to perform in-vitro and in-vivo radiopharmacological characterizations of [18F]2FNQ1P, a new PET radiotracer of 5-HT6 receptors, in rat, pig, non-human primate and human tissues. The 5-HT6 receptor is one of the more recently identified serotonin receptors in central nervous system and, because of its role in memory and cognitive processes, is considered as a promising therapeutic target. METHODS In-vitro autoradiography and saturation binding assays were performed in postmortem brain tissues from rat, pig, non-human primate and human caudate nucleus, completed by serum stability assessment in all species and cerebral radiometabolite and biodistribution studies in rat. RESULTS In all species, autoradiography data revealed high binding levels of [18F]2FNQ1P in cerebral regions with high 5-HT6 receptor density. Binding was blocked by addition of SB258585 as a specific antagonist. Binding assays provided KD and Bmax values of respectively 1.34 nM and 0.03 pmol·mg-1 in rat, 0.60 nM and 0.04 pmol·mg-1 in pig, 1.38 nM and 0.07 pmol·mg-1 in non-human primate, and 1.39 nM and 0.15 pmol·mg-1 in human caudate nucleus. In rat brain, the proportion of unmetabolized [18F]2FNQ1P was >99% 5 min after iv injection and 89% at 40 min. The biodistribution studies found maximal radioactivity in lungs and kidneys (3.5 ± 1.2% ID/g and 2.0 ± 0.7% ID/g, respectively, 15 min post-injection). CONCLUSION These radiopharmacological data confirm that [18F]2FNQ1P is a specific radiotracer for molecular imaging of 5-HT6 receptors and suggest that it could be used as a radiopharmaceutical in humans.
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Affiliation(s)
- Stéphane Emery
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, Lyon, France; Hospices Civils de Lyon, Bron, France
| | - Sylvain Fieux
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, Lyon, France
| | - Benjamin Vidal
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, Lyon, France
| | - Pierre Courault
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, Lyon, France; Hospices Civils de Lyon, Bron, France
| | - Sandrine Bouvard
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, 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, CNRS, INSERM, Lyon, France; Hospices Civils de Lyon, Bron, France; CERMEP Imaging Platform, Bron, France; National Institute for Nuclear Science and Technology INSTN, CEA, Saclay, France.
| | - Sophie Lancelot
- Lyon Neuroscience Research Center, Université de Lyon, CNRS, INSERM, Lyon, France; Hospices Civils de Lyon, Bron, France; CERMEP Imaging Platform, Bron, France
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Vidal B, Karpenko IA, Liger F, Fieux S, Bouillot C, Billard T, Hibert M, Zimmer L. [ 11 C]PF-3274167 as a PET radiotracer of oxytocin receptors: Radiosynthesis and evaluation in rat brain. Nucl Med Biol 2017; 55:1-6. [DOI: 10.1016/j.nucmedbio.2017.07.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/24/2017] [Accepted: 07/29/2017] [Indexed: 01/30/2023]
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Ferreri F, Drapier D, Baloche E, Ouzid M, Zimmer L, Llorca PM. The in Vitro Actions of Loxapine on Dopaminergic and Serotonergic Receptors. Time to Consider Atypical Classification of This Antipsychotic Drug? Int J Neuropsychopharmacol 2017; 21:355-360. [PMID: 29106549 PMCID: PMC5887516 DOI: 10.1093/ijnp/pyx102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 10/29/2017] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND The denomination of typical antipsychotic for loxapine has poor relation to current knowledge of the molecule's relevant modes of action. MATERIALS AND METHODS Competition binding experiments were performed on expressed human recombinant receptors in CHO cells and HEK-293 cells for D1 to D5, 5-HT1A, 5-HT2A, 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro autoradiographies using [11C]-Raclopride [18F]-Altanserin [18F]-MPPF [11C]-SB207145, and [18F]-2FNQ1P were measured in brain tissue of a male primate followed by addition of increasing doses of loxapine succinate. RESULTS In cell cultures, the measured Kb confirmed high affinity of loxapine for the D2; intermediate affinity for the D1, D4, D5, 5-HT2C receptorsl and a lack of affinity toward D3, 5-HT1A, 5-HT4, 5-HT6, and 5-HT7 receptors. In brain tissue, PET autoradiographies showed a radiopharmaceutical displacement at low concentrations of loxapine on D2 and 5-HT2A receptors. CONCLUSION This preclinical study reveals that loxapine receptorial spectrum is close to an "atypical" profile (D2/5HT2A ratio, 1.14). Loxapine is rightly classified as a DS-RAn agent in the Neuroscience Based Nomenclature classification.
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Affiliation(s)
- Florian Ferreri
- Sorbonne Universités, UPMC Paris, France,Department of Psychiatry, Hospital Saint-Antoine, Paris, France,Correspondence: Florian Ferreri, MD, PhD, UPMC Paris Univ-06, Paris, France; Department of Psychiatry, Hôpital Saint-Antoine, 184 rue du Faubourg Saint-Antoine 75012 Paris, France (, )
| | - Dominique Drapier
- Université de Rennes 1, Rennes, France,Department of Psychiatry, Rennes University Hospital, Rennes, France
| | | | | | - Luc Zimmer
- Université Claude Bernard Lyon1, CNRS, INSERM, Lyon, France,CERMEP-Imaging Platform, Hospices Civils de Lyon, Lyon, France
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Hazari PP, Pandey A, Chaturvedi S, Mishra AK. New Trends and Current Status of Positron-Emission Tomography and Single-Photon-Emission Computerized Tomography Radioligands for Neuronal Serotonin Receptors and Serotonin Transporter. Bioconjug Chem 2017; 28:2647-2672. [PMID: 28767225 DOI: 10.1021/acs.bioconjchem.7b00243] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The critical role of serotonin (5-hydroxytryptamine; 5-HT) and its receptors (5-HTRs) in the pathophysiology of diverse neuropsychiatric and neurodegenerative disorders render them attractive diagnostic and therapeutic targets for brain disorders. Therefore, the in vivo assessment of binding of 5-HT receptor ligands under a multitude of physiologic and pathologic scenarios may support more-accurate identification of disease and its progression and the patient's response to therapy as well as the screening of novel therapeutic strategies. The present Review aims to focus on the current status of radioligands used for positron-emission tomography (PET) and single-photon-emission computerized tomography (SPECT) imaging of human brain serotonin receptors. We further elaborate upon and emphasize the attributes that qualify a radioligand for theranostics on the basis of its frequency of use in clinics, its benefit to risk assessment in humans, and its continuous evolution, along with the major limitations.
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Affiliation(s)
- Puja Panwar Hazari
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Ankita Pandey
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Anil Kumar Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
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Sgambato-Faure V, Billard T, Météreau E, Duperrier S, Fieux S, Costes N, Tremblay L, Zimmer L. Characterization and Reliability of [ 18F]2FNQ1P in Cynomolgus Monkeys as a PET Radiotracer for Serotonin 5-HT 6 Receptors. Front Pharmacol 2017; 8:471. [PMID: 28769801 PMCID: PMC5513908 DOI: 10.3389/fphar.2017.00471] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 07/03/2017] [Indexed: 01/08/2023] Open
Abstract
Brain serotonin-6 receptor (5-HT6R) is the one of the most recently identified serotonin receptors. Accumulating evidence suggests that it is a potent therapeutic target for psychiatric and neurological diseases. Since [18F]2FNQ1P was recently proposed as the first fluorinated positron emission tomography (PET) radioligand for this receptor, the objective of the present study was to demonstrate its suitability for 5-HT6R neuroimaging in primates. [18F]2FNQ1P was characterized by in vitro autoradiography and in vivo PET imaging in cynomolgus monkeys. Following in vivo PET imaging, tracer binding indices were computed using the simplified reference tissue model and Logan graphical model, with cerebellum as reference region. The tracer binding reproducibility was assessed by test–retest in five animals. Finally, specificity was assessed by pre-injection of a 5-HT6R antagonist, SB258585. In vitro, results showed wide cerebral distribution of the tracer with specificity toward 5-HT6Rs as binding was effectively displaced by SB258585. In vivo brain penetration was good with reproducible distribution at cortical and subcortical levels. The automated method gave the best spatial normalization. The Logan graphical model showed the best tracer binding indices, giving the highest magnitude, lowest standard deviation and best reproducibility and robustness. Finally, 5-HT6R antagonist pre-injection significantly decreased [18F]2FNQ1P binding mainly in the striatum and sensorimotor cortex. Taken together, these preclinical results show that [18F]2FNQ1P is a good candidate to address 5-HT6 receptors in clinical studies.
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Affiliation(s)
- Véronique Sgambato-Faure
- Université Claude Bernard Lyon ILyon, France.,Institut des Sciences Cognitives Marc Jeannerod, CNRS UMR5229Bron, France
| | - Thierry Billard
- Université Claude Bernard Lyon ILyon, France.,Institut de Chimie et de Biochimie, CNRS UMR5246Villeurbanne, France
| | - Elise Météreau
- Université Claude Bernard Lyon ILyon, France.,Institut des Sciences Cognitives Marc Jeannerod, CNRS UMR5229Bron, France
| | - Sandra Duperrier
- Université Claude Bernard Lyon ILyon, France.,Institut des Sciences Cognitives Marc Jeannerod, CNRS UMR5229Bron, France
| | - Sylvain Fieux
- Université Claude Bernard Lyon ILyon, France.,Centre de Recherche en Neurosciences de Lyon, CNRS UMR5292, INSERM U1028Lyon, France
| | | | - Léon Tremblay
- Université Claude Bernard Lyon ILyon, France.,Institut des Sciences Cognitives Marc Jeannerod, CNRS UMR5229Bron, France
| | - Luc Zimmer
- Université Claude Bernard Lyon ILyon, France.,Centre de Recherche en Neurosciences de Lyon, CNRS UMR5292, INSERM U1028Lyon, France.,CERMEP-Imagerie du VivantLyon, France.,Hospices Civils de LyonLyon, France
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Dopamine and serotonin modulation of motor and non-motor functions of the non-human primate striato-pallidal circuits in normal and pathological states. J Neural Transm (Vienna) 2017; 125:485-500. [PMID: 28176009 DOI: 10.1007/s00702-017-1693-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/30/2017] [Indexed: 10/20/2022]
Abstract
Thanks to the non-human primate (NHP), we have shown that the pharmacological disturbance of the anterior striatum or of external globus pallidus triggers a set of motivation and movement disorders, depending on the functional subterritory involved. One can, therefore, assume that the aberrant activity of the different subterritories of basal ganglia (BG) could lead to different behavioral disorders in neuropsychiatric disorders as Tourette's syndrome and Parkinson's disease. We are now addressing in the NHP the impact of modulating dopamine or serotonin within the BG on behavioral disorders. Indeed, we have shown a prominent role of serotonergic degeneration within the ventral striatum and caudate nucleus in neuropsychiatric symptoms in de novo PD patients. Of note, the serotonergic modulation of these BG regions in the NHP plays also a critical role in the induction or treatment of behavioral disorders. Given that both dopamine and serotonin are targeted to treat neuropsychiatric disorders, we are studying the effects of modulating dopamine and serotonin transporters in the different territories of the striatum, and more particularly within the ventral striatum on decision-making processing at both behavioral and neuronal levels. Finally, we evidence the need to extend the pharmacological approach to the receptors of these two neuromodulator systems as the use of substances targeting receptor subtypes preferentially localized in the associative and limbic territories of BG could be very effective to specifically improve the behavioral disorders in Parkinson's disease, Gilles de la Tourette syndrome but also in several psychiatric disorders such as depression, anxiety, anorexia, or impulse control disorders.
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Serotonin 5-HT 6 Receptor Antagonists in Alzheimer's Disease: Therapeutic Rationale and Current Development Status. CNS Drugs 2017; 31:19-32. [PMID: 27914038 DOI: 10.1007/s40263-016-0399-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia in elderly people. Because of the lack of effective treatments for this illness, research focused on identifying compounds that restore cognition and functional impairments in patients with AD is a very active field. Since its discovery in 1993, the serotonin 5-HT6 receptor has received increasing attention, and a growing number of studies supported 5-HT6 receptor antagonism as a target for improving cognitive dysfunction in AD. This article reviews the rationale behind investigations into the targeting of 5-HT6 receptors as a symptomatic treatment for cognitive and/or behavioral symptoms of AD. In addition to describing the available clinical evidence, this article also describes the purported biochemical and neurochemical mechanisms of action by which 5-HT6 receptor antagonists could influence cognition, and the preclinical data supporting this therapeutic approach to AD. A large number of publications describing the development of ligands for this receptor have come to light and preclinical data indicate the procognitive efficacy of 5-HT6 receptor antagonists. Subsequently, the number of patents protecting 5-HT6 chemical entities has continuously grown. Some of these compounds have successfully undergone phase I clinical studies and have been further evaluated in clinical phase II trials with variable success. Phase II studies have also revealed the potential of combining 5-HT6 receptor antagonism and cholinesterase inhibition. Two of these antagonists, idalopirdine and RVT-101, have been further developed into ongoing phase III clinical trials. Overall, 5-HT6 receptor antagonists can reasonably be regarded as potential drug candidates for the treatment of AD.
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Hettie KS, Glass TE. Turn-On Near-Infrared Fluorescent Sensor for Selectively Imaging Serotonin. ACS Chem Neurosci 2016; 7:21-5. [PMID: 26521705 DOI: 10.1021/acschemneuro.5b00235] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A molecular imaging tool that provides for the direct visualization of serotonin would significantly aid in the investigation of neuropsychiatric disorders that are attributed to its neuronal dysregulation. Here, the design, synthesis, and evaluation of NeuroSensor 715 (NS715) is presented. NS715 is the first molecular sensor that exhibits a turn-on near-infrared fluorescence response toward serotonin. Density functional theory calculations facilitated the design of a fluorophore based on a coumarin-3-aldehyde scaffold that derives from an electron-rich 1,2,3,4-tetrahydroquinoxaline framework, which provides appropriate energetics to prevent the hydroxyindole moiety of serotonin from quenching its fluorescence emission. Spectroscopic studies revealed that NS715 produces an 8-fold fluorescence enhancement toward serotonin with an emission maximum at 715 nm. Accompanying binding studies indicated NS715 displays a 19-fold selective affinity for serotonin and a modest affinity for catecholamines over other primary-amine neurotransmitters. The utility of NS715 toward neuroimaging applications was validated by selectively labeling and directly imaging norepinephrine within secretory vesicles using live chromaffin cells, which serve as a model system for specialized neurons that synthesize, package, and release only a single, unique type of neurotransmitter. In addition, NS715 effectively differentiated between cell populations that express distinct neurotransmitter phenotypes.
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Affiliation(s)
- Kenneth S. Hettie
- Department
of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Timothy E. Glass
- Department
of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
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5-HT2A receptor SPECT imaging with [¹²³I]R91150 under P-gp inhibition with tariquidar: More is better? Nucl Med Biol 2015; 43:81-88. [PMID: 26454782 DOI: 10.1016/j.nucmedbio.2015.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/18/2015] [Accepted: 09/05/2015] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Pharmacological P-glycoprotein (P-gp) inhibition with tariquidar (TQD) is considered a promising strategy for the augmentation of radiotracer brain uptake. However, a region-dependent effect may compromise the robustness of quantitative studies. For this reason, we studied the effect of a TQD pretreatment on 5-HT2A imaging with [(123)I]R91150 and compared results with those obtained in Mdr1a knock-out (KO) rats. METHODS Ex vivo autoradiography was performed in TQD (15 mg/kg) pretreated wild-type (WT-TQD), Mdr1a knock-out (KO) and untreated WT rats for Specific Binding Ratio (SBR) estimation. In vivo dynamic SPECT imaging with serial arterial blood sampling was performed in the former two groups of rats and kinetic analysis was performed with a one tissue-compartment (1TC) model and the Specific Uptake Ratio (SUR). Results were analyzed statistically using repeated measures ANOVA. RESULTS SBR values differed between WT-TQD, Mdr1a KO and WT rats in a region-dependent manner (p<0.0001). In vivo brain uptake of radiotracer did not differ between groups. Similarly, kinetic analysis provided distribution volume (V(T)) values that did not differ significantly between groups. SUR binding potential (BPND) values from both groups highly correlated with corresponding V(T) (r=0.970, p<0.0001 and r=0.962, p<0.0001, respectively). However, SUR measured over averaged images between 100 and 120 min, using cerebellum as reference region, demonstrated values that were, by average, 2.99±0.53 times higher in the WT-TQD group, with the difference between groups being region-dependent (p<0.001). In addition, coefficient of variation of the SUR BPND values across brain regions was significantly higher in the WT-TQD rats (41.25%±9.63% versus 11.13%±5.59%, p<0.0001). CONCLUSION P-gp inhibition with TQD leads to region-dependent effect in the rat brain, with probably sub-optimal effect in cerebellum. This warrants attention when it is used as a reference region for quantitative studies.
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