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Mandeville JB, Weigand-Whittier J, Wey HY, Chen YCI. Amphetamine pretreatment blunts dopamine-induced D2/D3-receptor occupancy by an arrestin-mediated mechanism: A PET study in internalization compromised mice. Neuroimage 2023; 283:120416. [PMID: 37866759 PMCID: PMC10841768 DOI: 10.1016/j.neuroimage.2023.120416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 09/29/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023] Open
Abstract
While all reversible receptor-targeting radioligands for positron emission tomography (PET) can be displaced by competition with an antagonist at the receptor, many radiotracers show limited occupancies using agonists even at high doses. [11C]Raclopride, a D2/D3 receptor radiotracer with rapid kinetics, can identify the direction of changes in the neurotransmitter dopamine, but quantitative interpretation of the relationship between dopamine levels and radiotracer binding has proven elusive. Agonist-induced receptor desensitization and internalization, a homeostatic mechanism to downregulate neurotransmitter-mediated function, can shift radioligand-receptor binding affinity and confound PET interpretations of receptor occupancy. In this study, we compared occupancies induced by amphetamine (AMP) in drug-naive wild-type (WT) and internalization-compromised β-arrestin-2 knockout (KO) mice using a within-scan drug infusion to modulate the kinetics of [11C]raclopride. We additionally performed studies at 3 h following AMP pretreatment, with the hypothesis that receptor internalization should markedly attenuate occupancy on the second challenge, because dopamine cannot access internalized receptors. Without prior AMP treatment, WT mice exhibited somewhat larger binding potential than KO mice but similar AMP-induced occupancy. At 3 h after AMP treatment, WT mice exhibited binding potentials that were 15 % lower than KO mice. At this time point, occupancy was preserved in KO mice but suppressed by 60 % in WT animals, consistent with a model in which most receptors contributing to binding potential in WT animals were not functional. These results demonstrate that arrestin-mediated receptor desensitization and internalization produce large effects in PET [11C]raclopride occupancy studies using agonist challenges.
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Affiliation(s)
- Joseph B Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
| | - Jonah Weigand-Whittier
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Bioengineering, University of California, Berkeley, CA, USA
| | - Hsiao-Ying Wey
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Yin-Ching I Chen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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2
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Smith ALW, Harmer CJ, Cowen PJ, Murphy SE. The Serotonin 1A (5-HT 1A) Receptor as a Pharmacological Target in Depression. CNS Drugs 2023; 37:571-585. [PMID: 37386328 DOI: 10.1007/s40263-023-01014-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/15/2023] [Indexed: 07/01/2023]
Abstract
Clinical depression is a common, debilitating and heterogenous disorder. Existing treatments for depression are inadequate for a significant minority of patients and new approaches are urgently needed. A wealth of evidence implicates the serotonin 1A (5-HT1A) receptor in the pathophysiology of depression. Stimulation of the 5-HT1A receptor is an existing therapeutic target for treating depression and anxiety, using drugs such as buspirone and tandospirone. However, activation of 5-HT1A raphe autoreceptors has also been suggested to be responsible for the delay in the therapeutic action of conventional antidepressants such as selective serotonin reuptake inhibitors (SSRIs). This narrative review provides a brief overview of the 5-HT1A receptor, the evidence implicating it in depression and in the effects of conventional antidepressant treatment. We highlight that pre- and post-synaptic 5-HT1A receptors may have divergent roles in the pathophysiology and treatment of depression. To date, developing this understanding to progress therapeutic discovery has been limited, partly due to a paucity of specific pharmacological probes suitable for use in humans. The development of 5-HT1A 'biased agonism', using compounds such as NLX-101, offers the opportunity to further elucidate the roles of pre- and post-synaptic 5-HT1A receptors. We describe how experimental medicine approaches can be helpful in profiling the effects of 5-HT1A receptor modulation on the different clinical domains of depression, and outline some potential neurocognitive models that could be used to test the effects of 5-HT1A biased agonists.
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Affiliation(s)
- Alexander L W Smith
- Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Oxford, UK
| | - Catherine J Harmer
- Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Oxford, UK
| | - Philip J Cowen
- Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Oxford, UK
| | - Susannah E Murphy
- Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, OX3 7JX, UK.
- Oxford Health NHS Foundation Trust, Oxford, UK.
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3
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Dai J, Kim H, You Z, McCabe MF, Zhang S, Wang S, Lim G, Chen L, Mao J. Role of 5-HT1A-mediated upregulation of brain indoleamine 2,3 dioxygenase 1 in the reduced antidepressant and antihyperalgesic effects of fluoxetine during maintenance treatment. Front Pharmacol 2022; 13:1084108. [PMID: 36588734 PMCID: PMC9800882 DOI: 10.3389/fphar.2022.1084108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022] Open
Abstract
The reduced antidepressant and antihyperalgesic effects of selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine during maintenance treatment has been reported, but little is known about the molecular mechanism of this phenomenon. In three comorbid pain and depression animal models (genetic predisposition, chronic social stress, arthritis), we showed that the fluoxetine's antidepressant and antihyperalgesic effects were reduced during the maintenance treatment. Fluoxetine exposure induced upregulation of the 5-hydroxytryptamine 1A (5-HT1A) auto-receptor and indoleamine 2,3 dioxygenase 1 (IDO1, a rate-limiting enzyme of tryptophan metabolism) in the brainstem dorsal raphe nucleus (DRN), which shifted the tryptophan metabolism away from the 5-HT biosynthesis. Mechanistically, IDO1 upregulation was downstream to fluoxetine-induced 5-HT1A receptor expression because 1) antagonism of the 5-HT1A receptor with WAY100635 or 5-HT1A receptor knockout blocked the IDO1 upregulation, and 2) inhibition of IDO1 activity did not block the 5-HT1A receptor upregulation following fluoxetine exposure. Importantly, inhibition of either the 5-HT1A receptor or IDO1 activity sustained the fluoxetine's antidepressant and antihyperalgesic effects, indicating that 5-HT1A-mediated IDO1 upregulation in the brainstem DRN contributed to the reduced antidepressant and antihyperalgesic effects of fluoxetine. These results suggest a new strategy to improving the therapeutic efficacy of SSRI during maintenance treatment.
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Affiliation(s)
- Jiajia Dai
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States,Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Hyangin Kim
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States,*Correspondence: Jianren Mao, ; Hyangin Kim,
| | - Zerong You
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Michael F. McCabe
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Shuzhuo Zhang
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Shiyu Wang
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Grewo Lim
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Lucy Chen
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Jianren Mao
- MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States,*Correspondence: Jianren Mao, ; Hyangin Kim,
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4
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Colwell MJ, Tagomori H, Chapman S, Gillespie AL, Cowen PJ, Harmer CJ, Murphy SE. Pharmacological targeting of cognitive impairment in depression: recent developments and challenges in human clinical research. Transl Psychiatry 2022; 12:484. [PMID: 36396622 PMCID: PMC9671959 DOI: 10.1038/s41398-022-02249-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 11/01/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022] Open
Abstract
Impaired cognition is often overlooked in the clinical management of depression, despite its association with poor psychosocial functioning and reduced clinical engagement. There is an outstanding need for new treatments to address this unmet clinical need, highlighted by our consultations with individuals with lived experience of depression. Here we consider the evidence to support different pharmacological approaches for the treatment of impaired cognition in individuals with depression, including treatments that influence primary neurotransmission directly as well as novel targets such as neurosteroid modulation. We also consider potential methodological challenges in establishing a strong evidence base in this area, including the need to disentangle direct effects of treatment on cognition from more generalised symptomatic improvement and the identification of sensitive, reliable and objective measures of cognition.
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Affiliation(s)
- Michael J Colwell
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Hosana Tagomori
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Sarah Chapman
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
| | - Amy L Gillespie
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Philip J Cowen
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Catherine J Harmer
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Susannah E Murphy
- University Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK.
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK.
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5
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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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6
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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7
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Colom M, Vidal B, Fieux S, Redoute J, Costes N, Lavenne F, Mérida I, Irace Z, Iecker T, Bouillot C, Billard T, Newman-Tancredi A, Zimmer L. [ 18F]F13640, a 5-HT 1A Receptor Radiopharmaceutical Sensitive to Brain Serotonin Fluctuations. Front Neurosci 2021; 15:622423. [PMID: 33762906 PMCID: PMC7982540 DOI: 10.3389/fnins.2021.622423] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/17/2021] [Indexed: 12/30/2022] Open
Abstract
Introduction Serotonin is involved in a variety of physiological functions and brain disorders. In this context, efforts have been made to investigate the in vivo fluctuations of this neurotransmitter using positron emission tomography (PET) imaging paradigms. Since serotonin is a full agonist, it binds preferentially to G-protein coupled receptors. In contrast, antagonist PET ligands additionally interact with uncoupled receptors. This could explain the lack of sensitivity to serotonin fluctuations of current 5-HT1A radiopharmaceuticals which are mainly antagonists and suggests that agonist radiotracers would be more appropriate to measure changes in neurotransmitter release. The present study evaluated the sensitivity to endogenous serotonin release of a recently developed, selective 5-HT1A receptor PET radiopharmaceutical, the agonist [18F]F13640 (a.k.a. befiradol or NLX-112). Materials and Methods Four cats each underwent three PET scans with [18F]F13640, i.e., a control PET scan of 90 min, a PET scan preceded 30 min before by an intravenous injection 1 mg/kg of d-fenfluramine, a serotonin releaser (blocking challenge), and a PET scan comprising the intravenous injection of 1 mg/kg of d-fenfluramine 30 min after the radiotracer injection (displacement challenge). Data were analyzed with regions of interest and voxel-based approaches. A lp-ntPET model approach was implemented to determine the dynamic of serotonin release during the challenge study. Results D-fenfluramine pretreatment elicited a massive inhibition of [18F]F13640 labeling in regions known to express 5-HT1A receptors, e.g., raphe nuclei, hippocampus, thalamus, anterior cingulate cortex, caudate putamen, occipital, frontal and parietal cortices, and gray matter of cerebellum. Administration of d-fenfluramine during PET acquisition indicates changes in occupancy from 10% (thalamus) to 31% (gray matter of cerebellum) even though the dissociation rate of [18F]F13640 over the 90 min acquisition time was modest. The lp-ntPET simulation succeeded in differentiating the control and challenge conditions. Conclusion The present findings demonstrate that labeling of 5-HT1A receptors with [18F]F13640 is sensitive to serotonin concentration fluctuations in vivo. Although the data underline the need to perform longer PET scan to ensure accurate measure of displacement, they support clinical development of [18F]F13640 as a tool to explore experimental paradigms involving physiological or pathological (neurological or neuropsychiatric pathologies) fluctuations of extracellular serotonin.
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Affiliation(s)
- Matthieu Colom
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France.,Hospices Civils de Lyon, Lyon, France
| | - Benjamin Vidal
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Sylvain Fieux
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | | | | | | | | | | | | | | | | | | | - Luc Zimmer
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Université Claude Bernard Lyon 1, Lyon, France.,Hospices Civils de Lyon, Lyon, France.,CERMEP-Imagerie du Vivant, Bron, France.,Institut National des Sciences et Techniques Nucléaires, Gif-sur-Yvette, France
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8
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Deen M, Hougaard A, Hansen HD, Schain M, Dyssegaard A, Knudsen GM, Ashina M. Association Between Sumatriptan Treatment During a Migraine Attack and Central 5-HT1B Receptor Binding. JAMA Neurol 2020; 76:834-840. [PMID: 31135819 DOI: 10.1001/jamaneurol.2019.0755] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Importance Triptans, the most efficient acute treatment for migraine attacks, are 5-HT1B/1D receptor agonists, but their precise mechanism of action is not completely understood. The extent to which triptans enter the central nervous system and bind to 5-HT1B receptors in the brain is unknown. Objectives To determine the occupancy of sumatriptan to central 5-HT1B receptors, and to investigate changes in brain serotonin levels during migraine attacks. Design, Setting, and Participants This study of 8 patients in Denmark used a within-participant design and was conducted from April 20, 2015, to December 5, 2016. Participants were otherwise healthy patients with untreated episodic migraine without aura, aged between 18 and 65 years, and recruited from the general community. Data analysis was performed from January 2017 to April 2018. Interventions All participants underwent positron emission tomographic scans after injection of [11C]AZ10419369, a specific 5-HT1B receptor radiotracer. All participants were scanned 3 times: (1) during an experimentally induced migraine attack, (2) after a subcutaneous injection of 6-mg subcutaneous sumatriptan, and (3) on a migraine attack-free day. Scans 1 and 2 were conducted on the same study day. Each scan lasted for 90 minutes. Main Outcome and Measure The primary outcome was the nondisplaceable binding potential of [11C]AZ10419369 across 7 brain regions involved in pain modulation. The binding potential reflects receptor density, and changes in binding potential reflects displacement of the radiotracer. The occupancy of sumatriptan was estimated from the 2 scans before and after sumatriptan administration. Results Eight patients with migraine were included in the study; of these participants, 7 (87%) were women. The mean (SD) age of participants on study day 1 was 29.5 (9.2) years and on study day 2 was 30.0 (8.9) years. Sumatriptan was associated with statistically significantly reduced 5-HT1B receptor binding across pain-modulating regions (mean [SD] binding potential, 1.20 [0.20] vs 1.02 [0.22]; P = .001), corresponding to a mean (SD) drug occupancy rate of 16.0% (5.3%). Furthermore, during migraine attacks, as compared with outside of attacks, 5-HT1B receptor binding was statistically significantly associated with reduced in pain-modulating regions (mean [SD] binding potential, 1.36 [0.22] vs 1.20 [0.20]; P = .02). Conclusions and Relevance Treatment with sumatriptan during migraine attacks appeared to be associated with a decrease in 5-HT1B receptor binding, a finding that is most likely associated with the binding of sumatriptan to central 5-HT1B receptors, but the contribution of ongoing cerebral serotonin release to the lower binding cannot be excluded; the migraine attack-associated decrease in binding could indicate that migraine attacks are associated with increases in endogenous serotonin.
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Affiliation(s)
- Marie Deen
- Danish Headache Center, Department of Neurology, Rigshospitalet, Glostrup, Denmark.,Neurobiology Research Unit and NeuroPharm, Department of Neurology, Rigshospitalet, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders Hougaard
- Danish Headache Center, Department of Neurology, Rigshospitalet, Glostrup, Denmark
| | - Hanne Demant Hansen
- Neurobiology Research Unit and NeuroPharm, Department of Neurology, Rigshospitalet, Copenhagen, Denmark
| | - Martin Schain
- Neurobiology Research Unit and NeuroPharm, Department of Neurology, Rigshospitalet, Copenhagen, Denmark
| | - Agnete Dyssegaard
- Neurobiology Research Unit and NeuroPharm, Department of Neurology, Rigshospitalet, Copenhagen, Denmark
| | - Gitte Moos Knudsen
- Neurobiology Research Unit and NeuroPharm, Department of Neurology, Rigshospitalet, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Messoud Ashina
- Danish Headache Center, Department of Neurology, Rigshospitalet, Glostrup, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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9
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18F-F13640 preclinical evaluation in rodent, cat and primate as a 5-HT 1A receptor agonist for PET neuroimaging. Brain Struct Funct 2018; 223:2973-2988. [PMID: 29730825 DOI: 10.1007/s00429-018-1672-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 04/20/2018] [Indexed: 12/23/2022]
Abstract
Serotonin 1A receptors are known to play an important role in many psychiatric and neurodegenerative disorders. Currently, all available 5-HT1A receptor PET radiopharmaceuticals that are radiolabeled with fluorine-18 are antagonists. As agonists bind preferentially to the high-affinity state of receptors, it would be of great interest to develop agonist radioligands which could provide a measure of the functional 5-HT1A receptors in pathophysiological processes. The 5-HT1A receptor agonist candidates we recently proposed had promising in vitro properties but were not optimal in terms of PET imaging. F13640, a.k.a befiradol or NLX-112, is a 5-HT1A receptor agonist with a high affinity (Ki = 1 nM) and a high selectivity that would be suitable for a potential PET radiopharmaceutical. With propose here the first preclinical evaluation of 18F-F13640. 18F-F13640's nitro-precursor was synthesized and radiolabeled via a fluoro-nucleophilic substitution. Its radiopharmacological characterization included autoradiographic studies, metabolic studies, and in vivo PET scans in rat, cat and non-human primate. Some of the results were compared with the radiotracer 18F-MPPF, a 5-HT1A receptor antagonist. The radiochemical purity of 18F-F13640 was > 98%. In vitro binding pattern was consistent with the 5-HT1A receptor distribution. Metabolic studies revealed that the radiotracer rapidly entered the brain and led to few brain radiometabolites. Although 18F-F13640 in vivo binding was blocked by the 5-HT1A antagonist WAY-100635 and the 5-HT1A agonist 8-OH-DPAT, the distribution pattern was markedly different from antagonist radiotracers in the three species, suggesting it provides novel information on 5-HT1A receptors. Preliminary studies also suggest a high sensitivity of 18F-F13640 to endogenous serotonin release. 18F-F13640 has suitable characteristics for probing in vitro and in vivo the 5-HT1A receptors in high-affinity state. Quantification analyses with kinetic modeling are in progress to prepare the first-in-man study of 18F-F13640.
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10
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Yokoyama C, Mawatari A, Kawasaki A, Takeda C, Onoe K, Doi H, Newman-Tancredi A, Zimmer L, Onoe H. Marmoset Serotonin 5-HT1A Receptor Mapping with a Biased Agonist PET Probe 18F-F13714: Comparison with an Antagonist Tracer 18F-MPPF in Awake and Anesthetized States. Int J Neuropsychopharmacol 2016; 19:pyw079. [PMID: 27608810 PMCID: PMC5203761 DOI: 10.1093/ijnp/pyw079] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/05/2016] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND In vivo mapping by positron emission tomography of the serotonin 1A receptors has been hindered by the lack of suitable agonist positron emission tomography probes. 18F-labeled F13714 is a recently developed biased agonist positron emission tomography probe that preferentially targets subpopulations of serotonin 1A receptors in their "active state," but its brain labeling pattern in nonhuman primate has not been described. In addition, a potential confound in the translatability of PET data between nonhuman animal and human arise from the use of anesthetics that may modify the binding profiles of target receptors. METHODS Positron emission tomography scans were conducted in a cohort of common marmosets (n=4) using the serotonin 1A receptor biased agonist radiotracer, 18F-F13714, compared with a well-characterized 18F-labeled antagonist radiotracer, 18F-MPPF. Experiments on each animal were performed under both consciousness and isoflurane-anesthesia conditions. RESULTS 18F-F13714 binding distribution in marmosets by positron emission tomography differs markedly from that of the 18F-MPPF. Whereas 18F-MPPF showed highest binding in hippocampus and amygdala, 18F-F13714 showed highest labeling in other regions, including insular and cingulate cortex, thalamus, raphe, caudate nucleus, and putamen. The binding potential values of 18F-F13714 were about one-third of those observed with 18F-MPPF, with marked individual- and region-specific differences under isoflurane-anesthetized vs conscious conditions. CONCLUSIONS These findings highlight the importance of investigating the brain imaging of serotonin 1A receptors using agonist probes such as 18F-F13714, which may preferentially target subpopulations of serotonin 1A receptors in specific brain regions of nonhuman primate as a biased agonist.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hirotaka Onoe
- RIKEN Center for Life Science Technologies, Kobe, Hyogo, Japan (Dr Yokoyama, Ms Mawatari, Mr Kawasaki, Ms Takeda, Ms K. Onoe, Dr Doi, Dr H. Onoe); Neurolixis Inc, Dana Point, CA (Dr Newman-Tancredi); Université Claude Bernard Lyon 1, Hospices Civils de Lyon, INSERM, CNRS, Lyon Neuroscience Research Center, Lyon, France (Dr Zimmer).
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11
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Sanchez C, Asin KE, Artigas F. Vortioxetine, a novel antidepressant with multimodal activity: Review of preclinical and clinical data. Pharmacol Ther 2015; 145:43-57. [DOI: 10.1016/j.pharmthera.2014.07.001] [Citation(s) in RCA: 315] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 07/02/2014] [Indexed: 12/21/2022]
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12
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Majo VJ, Milak MS, Prabhakaran J, Mali P, Savenkova L, Simpson NR, Mann JJ, Parsey RV, Dileep Kumar JS. Synthesis and in vivo evaluation of [(18)F]2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)-dione ([(18)F]FECUMI-101) as an imaging probe for 5-HT1A receptor agonist in nonhuman primates. Bioorg Med Chem 2013; 21:5598-604. [PMID: 23816046 PMCID: PMC3858174 DOI: 10.1016/j.bmc.2013.05.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/09/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
Abstract
The 5-HT1AR partial agonist PET radiotracer, [(11)C]CUMI-101, has advantages over an antagonist radiotracer as it binds preferentially to the high affinity state of the receptor and thereby provides more functionally meaningful information. The major drawback of C-11 tracers is the lack of cyclotron facility in many health care centers thereby limiting widespread clinical or research use. We identified the fluoroethyl derivative, 2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)dione (FECUMI-101) (Ki=0.1nM; Emax=77%; EC50=0.65nM) as a partial agonist 5-HT1AR ligand of the parent ligand CUMI-101. FECUMI-101 is radiolabeled with F-18 by O-fluoroethylation of the corresponding desmethyl analogue (1) with [(18)F]fluoroethyltosylate in DMSO in the presence of 1.6equiv of K2CO3 in 45±5% yield (EOS). PET shows [(18)F]FECUMI-101 binds specifically to 5-HT1AR enriched brain regions of baboon. The specificity of [(18)F]FECUMI-101 binding to 5-HT1AR was confirmed by challenge studies with the known 5-HT1AR ligand WAY100635. These findings indicate that [(18)F]FECUMI-101 can be a viable agonist ligand for the in vivo quantification of high affinity 5-HT1AR with PET.
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Affiliation(s)
- Vattoly J. Majo
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
| | - Matthew S. Milak
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
- Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York
| | - Jaya Prabhakaran
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
| | - Pratap Mali
- Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York
| | - Lyudmila Savenkova
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
| | - Norman R. Simpson
- Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York
| | - J. John Mann
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
- Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York
- Department of Radiology, Columbia University, New York, NY 10032
| | - Ramin V. Parsey
- Department of Psychiatry and Behavioral Science, Stony Brook University, New York
| | - J. S. Dileep Kumar
- Department of Psychiatry, Columbia University Medical Center, Columbia University, New York
- Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, New York
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13
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Varnäs K, Jučaitė A, McCarthy DJ, Stenkrona P, Nord M, Halldin C, Farde L, Kanes S. A PET study with [11C]AZ10419369 to determine brain 5-HT1B receptor occupancy of zolmitriptan in healthy male volunteers. Cephalalgia 2013; 33:853-60. [DOI: 10.1177/0333102413476372] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aim To investigate the occupancy at brain 5-hydroxytryptamine (5-HT) 1B receptors in human subjects after administration of the antimigraine drug zolmitriptan. Methods Positron emission tomography (PET) studies were undertaken using the radioligand [11C]AZ10419369 in eight control subjects at baseline and after administration of zolmitriptan orodispersible tablets. The subjects were examined after two consecutive administrations of 10 mg zolmitriptan, approximately 1 week apart. Two of the subjects were subsequently examined after administration of 5 mg zolmitriptan. One week after the last administration of zolmitriptan five of the subjects underwent additional PET measurements without drug pretreatment. Results After administration of 10 mg zolmitriptan, mean receptor occupancy was 4–5%. No consistent changes in 5-HT1B receptor binding were observed for subjects who received 5 mg zolmitriptan. There was a statistically significant negative relationship between binding potential ( BPND) and plasma concentration of zolmitriptan and the active metabolite 183C91, respectively. All of the five subjects who were examined 1 week after dosing with zolmitriptan showed higher BPND post drug administration compared with baseline. Conclusion This is the first demonstration of CNS 5-HT1B receptor occupancy of a triptan. The findings are consistent with the low receptor occupancy previously reported in PET studies with agonists at other G protein coupled receptors.
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Affiliation(s)
- Katarina Varnäs
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
| | - Aurelija Jučaitė
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
- AstraZeneca R&D, Clinical Development, Sweden
| | | | - Per Stenkrona
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
| | - Magdalena Nord
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
| | - Lars Farde
- Karolinska Institutet, Department of Clinical Neuroscience, Sweden
- AstraZeneca iMed CNS/P, Sweden
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Evaluation of dopamine D₂/D₃ and serotonin 5-HT₂A receptor occupancy for a novel antipsychotic, lurasidone, in conscious common marmosets using small-animal positron emission tomography. Psychopharmacology (Berl) 2013; 225:329-39. [PMID: 22868411 DOI: 10.1007/s00213-012-2815-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 07/17/2012] [Indexed: 12/13/2022]
Abstract
RATIONALE Lurasidone is a novel antipsychotic drug with potent binding affinity for dopamine D(2) and serotonin (5-hydroxytryptamine, 5-HT)(2A), 5-HT(7), and 5-HT(1A) receptors. Previous pharmacological studies have revealed that lurasidone exhibits a preferable profile (potent antipsychotic activity and lower incidence of catalepsy) to other antipsychotic drugs, although the contribution of receptor subtypes to this profile remains unclear. OBJECTIVES To compare target engagements of lurasidone with those of an atypical antipsychotic, olanzapine, we performed evaluation of dopamine D(2)/D(3) and serotonin 5-HT(2A) receptor occupancy in vivo by positron emission tomography (PET) with conscious common marmosets. METHODS We measured brain receptor occupancies in conscious common marmosets after oral administrations of lurasidone or olanzapine by PET with [(11)C]raclopride and [(11)C]R-(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine methanol (MDL 100907) for D(2)/D(3) and 5-HT(2A) receptors, respectively. RESULTS Increases in brain D(2)/D(3) receptor occupancies of both lurasidone and olanzapine, which reached >80 % at maximum, were observed in the striatum with significant correlations to plasma drug levels. However, lurasidone showed lower 5-HT(2A) receptor occupancy in the frontal cortex within the same dose range, while olanzapine showed broadly comparable 5-HT(2A) and D(2)/D(3) receptor occupancies. CONCLUSIONS Compared with olanzapine, lurasidone preferentially binds to D(2)/D(3) receptors rather than 5-HT(2A) receptors in common marmosets. These results suggest that the contribution of in vivo 5-HT(2A) receptor blocking activity to the pharmacological profile of lurasidone might differ from olanzapine in terms of the low risk of extrapyramidal syndrome and efficacy against negative symptoms.
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Saijo T, Maeda J, Okauchi T, Maeda JI, Morio Y, Kuwahara Y, Suzuki M, Goto N, Fukumura T, Suhara T, Higuchi M. Presynaptic selectivity of a ligand for serotonin 1A receptors revealed by in vivo PET assays of rat brain. PLoS One 2012; 7:e42589. [PMID: 22880045 PMCID: PMC3413639 DOI: 10.1371/journal.pone.0042589] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 07/10/2012] [Indexed: 11/19/2022] Open
Abstract
A novel investigational antidepressant with high affinity for the serotonin transporter and the serotonin 1A (5-HT(1A)) receptor, called Wf-516 (structural formula: (2S)-1-[4-(3,4-dichlorophenyl)piperidin-1-yl]-3-[2-(5-methyl-1,3,4-oxadiazol-2-yl)benzo[b]furan-4-yloxy]propan-2-ol monohydrochloride), has been found to exert a rapid therapeutic effect, although the mechanistic basis for this potential advantage remains undetermined. We comparatively investigated the pharmacokinetics and pharmacodynamics of Wf-516 and pindolol by positron emission tomographic (PET) and autoradiographic assays of rat brains in order to elucidate their molecular interactions with presynaptic and postsynaptic 5-HT(1A) receptors. In contrast to the full receptor occupancy by pindolol in PET measurements, the binding of Wf-516 to 5-HT(1A) receptors displayed limited capacity, with relatively high receptor occupancy being achieved in regions predominantly containing presynaptic receptors. This selectivity was further proven by PET scans of neurotoxicant-treated rats deficient in presynaptic 5-HT(1A) receptors. In addition, [(35)S]guanosine 5'-O-[γ-thio]triphosphate autoradiography indicated a partial agonistic ability of Wf-516 for 5-HT(1A) receptors. This finding has lent support to reports that diverse partial agonists for 5-HT(1A) receptors exert high sensitivity for presynaptic components. Thus, the present PET data suggest a relatively high capacity of presynaptic binding sites for partial agonists. Since our in vitro and ex vivo autoradiographies failed to illustrate these distinct features of Wf-516, in vivo PET imaging is considered to be, thus far, the sole method capable of pharmacokinetically demonstrating the unique actions of Wf-516 and similar new-generation antidepressants.
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Affiliation(s)
- Takeaki Saijo
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
- Department of Molecular Neuroimaging, Tohoku University School of Medicine, Sendai, Japan
- DMPK Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Kisarazu, Japan
| | - Jun Maeda
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Takashi Okauchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Jun-ichi Maeda
- Research Quality Assurance Department, Mitsubishi Tanabe Pharma Corporation, Yokohama, Japan
| | - Yasunori Morio
- Development Project Management Department, Mitsubishi Tanabe Pharma Corporation, Tokyo, Japan
| | - Yasuhiro Kuwahara
- Advanced Medical Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Yokohama, Japan
| | - Masayuki Suzuki
- DMPK Research Laboratory, Mitsubishi Tanabe Pharma Corporation, Kisarazu, Japan
| | - Nobuharu Goto
- Early Stage Clinical Research Center, Mitsubishi Tanabe Pharma Corporation, Tokyo, Japan
| | - Toshimitsu Fukumura
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
| | - Tetsuya Suhara
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
- Department of Molecular Neuroimaging, Tohoku University School of Medicine, Sendai, Japan
| | - Makoto Higuchi
- Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
- Department of Molecular Neuroimaging, Tohoku University School of Medicine, Sendai, Japan
- * E-mail:
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Comparative pharmacology of antipsychotics possessing combined dopamine D2 and serotonin 5-HT1A receptor properties. Psychopharmacology (Berl) 2011; 216:451-73. [PMID: 21394633 DOI: 10.1007/s00213-011-2247-y] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 02/22/2011] [Indexed: 02/07/2023]
Abstract
RATIONALE There is increasing interest in antipsychotics intended to manage positive symptoms via D(2) receptor blockade and improve negative symptoms and cognitive deficits via 5-HT(1A) activation. Such a strategy reduces side-effects such as the extrapyramidal syndrome (EPS), weight gain, and autonomic disturbance liability. OBJECTIVE This study aims to review pharmacological literature on compounds interacting at both 5-HT(1A) and D(2) receptors (as well as at other receptors), including aripiprazole, perospirone, ziprasidone, bifeprunox, lurasidone and cariprazine, PF-217830, adoprazine, SSR181507, and F15063. METHODS We examine data on in vitro binding and agonism and in vivo tests related to (1) positive symptoms (e.g., psychostimulant-induced hyperactivity or prepulse inhibition deficit), (2) negative symptoms (e.g., phencyclidine-induced social interaction deficits and cortical dopamine release), and (3) cognitive deficits (e.g., phencyclidine or scopolamine-induced memory deficits). EPS liability is assessed by measuring catalepsy and neuroendocrine impact by determining plasma prolactin, glucose, and corticosterone levels. RESULTS Compounds possessing "balanced" 5-HT(1A) receptor agonism and D(2) antagonism (or weak partial agonism) and, in some cases, combined with other beneficial properties, such as 5-HT(2A) receptor antagonism, are efficacious in a broad range of rodent pharmacological models yet have a lower propensity to elicit EPS or metabolic dysfunction. CONCLUSIONS Recent compounds exhibiting combined 5-HT(1A)/D(2) properties may be effective in treating a broader range of symptoms of schizophrenia and be better tolerated than existing antipsychotics. Nevertheless, further investigations are necessary to evaluate recent compounds, notably in view of their differing levels of 5-HT(1A) affinity and efficacy, which can markedly influence activity and side-effect profiles.
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Frankle WG, Lombardo I, Kegeles LS, Slifstein M, Martin JH, Huang Y, Hwang DR, Reich E, Cangiano C, Gil R, Abi-Dargham A, Laruelle M. Measurement of the serotonin 1A receptor availability in patients with schizophrenia during treatment with the antipsychotic medication ziprasidone. J Psychopharmacol 2011; 25:734-43. [PMID: 21109614 DOI: 10.1177/0269881110388329] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study was to compare 5-HT(1A) availability in vivo in individuals with schizophrenia before and during treatment with the atypical antipsychotic ziprasidone. Six individuals with schizophrenia underwent two PET scans with [(11)C]WAY 100635; the first while medication-free (baseline) and the second while taking the atypical antipsychotic ziprasidone (on-medication). Regional volumes of distribution (V(T), mL g(-1)) were derived using a two-tissue compartment kinetic model. Outcome measures included binding potential relative to the plasma (BP(P), mL g(-1)) and the binding potential relative to the nonspecific distribution volume (BP(ND), unitless). No significant differences were observed in regional BP(P) or BP(ND) with ziprasidone treatment. A significant correlation was noted between BP(P) measured in the orbitofrontal cortex during the on-medication condition and degree of improvement in negative symptoms with treatment (r = 0.96, p = 0.004). Consistent with the published literature of changes in 5-HT(1A) binding during treatment with 5-HT(1A) receptor agonists, this study did not detect a significant reduction in 5-HT(1A) binding with ziprasidone. The finding of a relationship between 5-HT(1A) binding and the degree of improvement in negative symptoms provides further support for the role of the 5-HT(1A) receptor in the pathophysiology and treatment of this symptom domain.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, USA.
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Ridler K, Plisson C, Rabiner EA, Gunn RN, Easwaramoorthy B, Abi-Dargham A, Laruelle M, Slifstein M. Characterization of in vivo pharmacological properties and sensitivity to endogenous serotonin of [11C] P943: A positron emission tomography study in Papio anubis. Synapse 2011; 65:1119-27. [DOI: 10.1002/syn.20946] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 04/21/2011] [Indexed: 11/08/2022]
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Bang-Andersen B, Ruhland T, Jørgensen M, Smith G, Frederiksen K, Jensen KG, Zhong H, Nielsen SM, Hogg S, Mørk A, Stensbøl TB. Discovery of 1-[2-(2,4-dimethylphenylsulfanyl)phenyl]piperazine (Lu AA21004): a novel multimodal compound for the treatment of major depressive disorder. J Med Chem 2011; 54:3206-21. [PMID: 21486038 DOI: 10.1021/jm101459g] [Citation(s) in RCA: 309] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The synthesis and structure-activity relationship of a novel series of compounds with combined effects on 5-HT(3A) and 5-HT(1A) receptors and on the serotonin (5-HT) transporter (SERT) are described. Compound 5m (Lu AA21004) was the lead compound, displaying high affinity for recombinant human 5-HT(1A) (K(i) = 15 nM), 5-HT(1B) (K(i) = 33 nM), 5-HT(3A) (K(i) = 3.7 nM), 5-HT(7) (K(i) = 19 nM), and noradrenergic β(1) (K(i) = 46 nM) receptors, and SERT (K(i) = 1.6 nM). Compound 5m displayed antagonistic properties at 5-HT(3A) and 5-HT(7) receptors, partial agonist properties at 5-HT(1B) receptors, agonistic properties at 5-HT(1A) receptors, and potent inhibition of SERT. In conscious rats, 5m significantly increased extracellular 5-HT levels in the brain after acute and 3 days of treatment. Following the 3-day treatment (5 or 10 (mg/kg)/day) SERT occupancies were only 43% and 57%, respectively. These characteristics indicate that 5m is a novel multimodal serotonergic compound, and 5m is currently in clinical development for major depressive disorder.
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Affiliation(s)
- Benny Bang-Andersen
- Neuroscience Drug Discovery Denmark, H. Lundbeck A/S , 9 Ottiliavej, DK-2500 Copenhagen-Valby, Denmark.
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Milak MS, DeLorenzo C, Zanderigo F, Prabhakaran J, Kumar JSD, Majo VJ, Mann JJ, Parsey RV. In vivo quantification of human serotonin 1A receptor using 11C-CUMI-101, an agonist PET radiotracer. J Nucl Med 2010; 51:1892-900. [PMID: 21098796 DOI: 10.2967/jnumed.110.076257] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED The serotonin (5-hydroxytryptamine, or 5-HT) type 1A receptor (5-HT(1A)R) is implicated in the pathophysiology of numerous neuropsychiatric disorders. We have published the initial evaluation and reproducibility in vivo of [O-methyl-(11)C]2-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)dione ((11)C-CUMI-101), a novel 5-HT(1A) agonist radiotracer, in Papio anubis. Here, we report the optimal modeling parameters of (11)C-CUMI-101 for human PET studies. METHODS PET scans were obtained for 7 adult human volunteers. (11)C-CUMI-101 was injected as an intravenous bolus, and emission data were collected for 120 min in 3-dimensional mode. We evaluated 10 different models using metabolite-corrected arterial input functions or reference region approaches and several outcome measures. RESULTS When using binding potential (BP(F) = B(avail)/K(D) [total available receptor concentration divided by the equilibrium dissociation constant]) as the outcome measure, the likelihood estimation in the graphical analysis (LEGA) model performed slightly better than the other methods evaluated at full scan duration. The average test-retest percentage difference was 9.90% ± 5.60%. When using BP(ND) (BP(ND) = f(nd) × B(avail)/K(D); BP(ND) equals the product of BP(F) and f(nd) [free fraction in the nondisplaceable compartment]), the simplified reference tissue method (SRTM) achieved the lowest percentage difference and smallest bias when compared with nondisplaceable binding potential obtained from LEGA using the metabolite-corrected plasma input function (r(2) = 0.99; slope = 0.92). The time-stability analysis indicates that a 120-min scan is sufficient for the stable estimation of outcome measures. Voxel results were comparable to region-of-interest-based analysis, with higher spatial resolution. CONCLUSION On the basis of its measurable and stable free fraction, high affinity and selectivity, good blood-brain barrier permeability, and plasma and brain kinetics, (11)C-CUMI-101 is suitable for the imaging of high-affinity 5-HT(1A) binding in humans.
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Affiliation(s)
- Matthew S Milak
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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Bollinger S, Hübner H, Heinemann FW, Meyer K, Gmeiner P. Novel pyridylmethylamines as highly selective 5-HT(1A) superagonists. J Med Chem 2010; 53:7167-79. [PMID: 20860381 DOI: 10.1021/jm100835q] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To further improve the maximal serotonergic efficacy and better understand the configurational requirements for 5-HT(1A) binding and activation, we generated and biologically investigated structural variants of the lead structure befiradol. For a bioisosteric replacement of the 3-chloro-4-fluoro moiety, a focused library of 63 compounds by solution phase parallel synthesis was developed. Target binding of our compound collection was investigated, and their affinities for 5-HT(2), α(1), and α(2)-adrenergic as well as D(1)-D(4) dopamine receptors were compared. For particularly interesting test compounds, intrinsic activities at 5-HT(1A) were examined in vitro employing a GTPγS assay. The investigation guided us to highly selective 5HT(1A) superagonists. The benzothiophene-3-carboxamide 8bt revealed almost exclusive 5HT(1A) recognition with a K(i) value of 2.7 nM and a maximal efficacy of 124%. To get insights into the bioactive conformation of our compound collection, we synthesized conformationally constrained bicyclic scaffolds when SAR data indicated a chair-type geometry and an equatorially dispositioned aminomethyl substituent for the 4,4-disubstituted piperidine moiety.
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Affiliation(s)
- Stefan Bollinger
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
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Abstract
Recent advances in the development and applications of neurochemical brain imaging methods have improved the ability to study the neurochemistry of the living brain in normal processes as well as psychiatric disorders. In particular, positron emission tomography (PET) and single photon emission computed tomography (SPECT) have been used to determine neurochemical substrates of schizophrenia and to uncover the mechanism of action of antipsychotic medications. The growing availability of radiotracers for monoaminergic neurotransmitter synthesis, transporters and receptors, has enabled the evaluation of hypotheses regarding neurotransmitter function in schizophrenia derived from preclinical and clinical observations. This chapter reviews the studies using neurochemical brain imaging methods for (1) detection of abnormalities in indices of dopamine and serotonin transmission in patients with schizophrenia compared to controls, (2) development of new tools to study other neurotransmitters systems, such as gamma-aminobutyric acid (GABA) and glutamate, and (3) characterization of target occupancy by antipsychotic drugs, as well as its relationship to efficacy and side effects. As more imaging tools become available, this knowledge will expand and will lead to better detection of disease, as well as better therapeutic approaches.
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Affiliation(s)
- Nina Urban
- Department of Psychiatry, New York State Psychiatric Institute, Columbia University, New York, NY 10032, USA.
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Influence of escitalopram treatment on 5-HT 1A receptor binding in limbic regions in patients with anxiety disorders. Mol Psychiatry 2009; 14:1040-50. [PMID: 18362913 DOI: 10.1038/mp.2008.35] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is an increasing interest in the underlying mechanisms of the antidepressant and anxiolytic treatment effect associated with changes in serotonergic neurotransmission after treatment with selective serotonin (5-HT) reuptake inhibitors (SSRIs) in humans. The 5-HT(1A) receptor is known to play a crucial role in the pathophysiology of affective disorders, and altered 5-HT(1A) receptor binding has been found in anxiety patients. SSRI treatment raises the 5-HT level in the synaptic cleft and might change postsynaptic receptor densities. Therefore, our study in patients suffering from anxiety disorders investigated the effects of long-term treatment with escitalopram on the 5-HT(1A) receptor. A longitudinal positrone emission tomography (PET) study in 12 patients suffering from anxiety disorders was conducted. Two dynamic PET scans were performed applying the selective 5-HT(1A) receptor antagonist [carbonyl-(11)C]WAY-100635. Eight regions of interest were defined a priori (orbitofrontal cortex, amygdala, hippocampus, subgenual cortex, anterior and posterior cingulate cortex, dorsal raphe nucleus and cerebellum as reference). After the baseline PET scan, patients were administered escitalopram (average dose of 11.2+/-6.0 mg day(-1)) for a minimum of 12 weeks. A second PET scan was conducted after 109+/-27 days. 5-HT(1A) receptor binding potentials in 12 patients were assessed by PET applying the Simplified Reference Tissue Model.There was a significant reduction in the 5-HT(1A) receptor binding potential after a minimum of 12 weeks of escitalopram treatment in the hippocampus (P=0.006), subgenual cortex (P=0.017) and posterior cingulate cortex (P=0.034). The significance of the hippocampus region survived the Bonferroni-adjusted threshold for multiple comparisons. These PET data in humans in vivo demonstrate a reduction of the 5-HT(1A) binding potential after SSRI treatment.
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Grimwood S, Hartig PR. Target site occupancy: Emerging generalizations from clinical and preclinical studies. Pharmacol Ther 2009; 122:281-301. [DOI: 10.1016/j.pharmthera.2009.03.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 01/17/2023]
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Truchot L, Costes N, Zimmer L, Laurent B, Le Bars D, Thomas-Antérion C, Mercier B, Hermier M, Vighetto A, Krolak-Salmon P. A distinct [18F]MPPF PET profile in amnestic mild cognitive impairment compared to mild Alzheimer's disease. Neuroimage 2008; 40:1251-6. [DOI: 10.1016/j.neuroimage.2008.01.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 11/18/2007] [Accepted: 01/08/2008] [Indexed: 10/22/2022] Open
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Majo VJ, Parsey RV, Prabhakaran J, Mann JJ, Dileep Kumar JS. Synthesis and evaluation of [O-methyl-11C]4-[3-[4-(2-methoxyphenyl)- piperazin-1-yl]propoxy]-4-aza-tricyclo[5.2.1.02,6]dec-8-ene-3,5-dione as a 5-HT1A receptor agonist PET ligand. J Labelled Comp Radiopharm 2008. [DOI: 10.1002/jlcr.1475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Moeller O, Evers S, Deckert J, Baune BT, Dannlowski U, Nguyen DH, Arolt V, Hetzel G. The impact of ziprasidone in combination with sertraline on visually-evoked event-related potentials in depressed patients with psychotic features. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:1440-3. [PMID: 17669572 DOI: 10.1016/j.pnpbp.2007.06.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2007] [Revised: 06/20/2007] [Accepted: 06/22/2007] [Indexed: 11/23/2022]
Abstract
BACKGROUND The use of atypical antipsychotics in major depression complicated by psychotic features has not been extensively investigated. Event-related potentials (ERP) have been reported to be impaired in depressed patients, probably due to serotonergic hypofunction. The objective of this study was to examine the effects of a combination therapy with ziprasidone and sertraline on ERP in major depression with psychotic features. METHODS 19 patients with major depression with psychotic features were treated with ziprasidone and sertraline. Before and after four weeks of treatment, visually-evoked ERP (P3 -- oddball paradigm) were investigated. RESULTS While a significant clinical improvement assessed with the Brief Psychiatric Rating Scale and Hamilton Depression Rating Scale was noted, no significant changes in weight, basal prolactin values and scores on the Extrapyramidal Symptoms Scale were observed. A significant prolongation (p = 0.041) of the QTc-interval between baseline and endpoint showed no clinical symptoms. Combination treatment with ziprasidone and sertraline over 4 weeks was associated with a significant decrease (p = 0.033) of P3 latencies from baseline to week 4. After a four week treatment, significantly (p = 0.008) fewer patients showed pathologically P3 latencies (>450 ms) than at baseline. DISCUSSION Our data, showing that ziprasidone in combination with sertraline lead to a decrease of prolonged P3 latencies, are in line with previous studies showing a decrease of prolonged P3 latencies by antidepressant treatment.
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Affiliation(s)
- O Moeller
- Department of Psychiatry and Psychotherapy, RWTH Aachen University, Pauwelsstrasse 30, D-52074 Aachen, Germany.
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Abstract
The ability of SPECT and PET to image specific biomolecules in the living brain provides a unique tool for clinical researchers. It is therefore not surprising that the use of neuroreceptor-imaging techniques has become more widespread over the past decade. This article reviews the application of these techniques to the study of schizophrenia. The design of neuroreceptor-imaging studies performed in the field of schizophrenia research can be broadly divided into two categories: (1) studies of pathophysiology and (2) studies of pharmacology. The former examines neuroreceptor and neurotransmitter parameters in individuals with schizophrenia compared to control subjects in order to provide a better understanding of the disease process. Studies of pharmacology seek to elucidate the mechanism of action for the treatments utilized in schizophrenia. This review will consider both studies of pathophysiology and pharmacology, with a discussion of the application of these techniques to drug development.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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Abstract
The serotonin 5-HT(1A) receptor is implicated in the pathophysiology of major neuropsychiatric disorders, including depression, suicidal behavior, panic disorder, epilepsy, bulimia, schizophrenia, Parkinson's disease, and Alzheimer's disease and is, therefore, an important target for drug therapy. 5-HT(1A) receptors are expressed as somatodendritic autoreceptors in serotonin neurons of the raphé nuclei (presynaptic) and as postsynaptic receptors in cortical and subcortical serotonin terminal fields in the brain. Due to the higher concentration and heterogeneous distribution of this receptor, it is an attractive target for quantification in vivo using positron emission tomography (PET) and single photon emission tomography (SPECT). Here, we review the PET radioligands employed for imaging 5-HT(1A) receptors in living brain.
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Affiliation(s)
- J S Dileep Kumar
- Department of Psychiatry, Columbia University College of Physicians and Surgeons & New York State Psychiatric Institute, New York, NY 10032, United States.
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Wong H, Dockens RC, Pajor L, Yeola S, Grace JE, Stark AD, Taub RA, Yocca FD, Zaczek RC, Li YW. 6-Hydroxybuspirone Is a Major Active Metabolite of Buspirone: Assessment of Pharmacokinetics and 5-Hydroxytryptamine1AReceptor Occupancy in Rats. Drug Metab Dispos 2007; 35:1387-92. [PMID: 17494642 DOI: 10.1124/dmd.107.015768] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pharmacokinetics and in vivo potency of 6-hydroxybuspirone (6-OH-buspirone), a major metabolite of buspirone, were investigated. The plasma clearance (47.3 +/- 3.5 ml/min/kg), volume of distribution (2.6 +/- 0.3 l/kg), and half-life (1.2 +/- 0.2 h) of 6-OH-buspirone in rats were similar to those for buspirone. Bioavailability was higher for 6-OH-buspirone (19%) compared with that for buspirone (1.4%). After intravenous infusions to steady-state levels in plasma, 6-OH-buspirone and buspirone increased 5-hydroxytryptamine (HT)(1A) receptor occupancy in a concentration-dependent manner with EC(50) values of 1.0 +/- 0.3 and 0.38 +/- 0.06 microM in the dorsal raphe and 4.0 +/- 0.6 and 1.5 +/- 0.3 microM in the hippocampus, respectively. Both compounds appeared to be approximately 4-fold more potent in occupying presynaptic 5-HT(1A) receptors in the dorsal raphe than the postsynaptic receptors in the hippocampus. Oral dosing of buspirone in rats resulted in exposures (area under the concentration-time profile) of 6-OH-buspirone and 1-(2-pyrimidinyl)-piperazine (1-PP), another major metabolite of buspirone, that were approximately 12 (6-OH-buspirone)- and 49 (1-PP)-fold higher than the exposure of the parent compound. As a whole, these preclinical data suggest that 6-OH-buspirone probably contributes to the clinical efficacy of buspirone as an anxiolytic agent.
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Affiliation(s)
- Harvey Wong
- Department of Metabolism and Pharmacokinetics, Pharmaceutical Research Institute, Bristol-Myers Squibb, Wallingford, Connecticut 06492-7660, USA
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Hume SP, Lingford-Hughes AR, Nataf V, Hirani E, Ahmad R, Davies AN, Nutt DJ. Low sensitivity of the positron emission tomography ligand [11C]diprenorphine to agonist opiates. J Pharmacol Exp Ther 2007; 322:661-7. [PMID: 17488881 DOI: 10.1124/jpet.107.121749] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previously, we reported minimal opioid receptor occupancy following a clinical dose of the micro-opioid agonist, methadone, measured in vivo using positron emission tomography (PET) with [(11)C]diprenorphine and subsequently used rats to obtain experimental data in support of a high receptor reserve hypothesis (Melichar et al., 2005). Here, we report on further preclinical studies investigating opioid receptor occupancy with oxycodone (micro- and kappa-receptor agonist), morphine (micro-receptor agonist), and buprenorphine (partial agonist at the micro-receptor and antagonist at the delta- and kappa-receptors), each given at antinociceptive doses. In vivo binding of [(11)C]diprenorphine was not significantly reduced after treatment with the full agonists but was reduced by approximately 90% by buprenorphine. In addition, given that [(11)C]diprenorphine is a non-subtype-specific PET tracer, there was no regional variation that might feasibly be interpreted as due to differences in opioid subtype distribution. The data support minimal competition between the high-efficacy agonists and the non-subtype-selective antagonist radioligand and highlight the limitations of [(11)C]diprenorphine PET to monitor in vivo occupancy. Alternative means may be needed to address clinical issues regarding opioid receptor occupancy that are required to optimize treatment strategies.
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Affiliation(s)
- Susan P Hume
- Hammersmith Imanet Ltd., Hammersmith Hospital, London, United Kingdom
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Henriksen G, Willoch F, Talbot PS, Wester HJ. Recent development and potential use of µ- and κ-opioid receptor ligands in positron emission tomography studies. Drug Dev Res 2007. [DOI: 10.1002/ddr.20161] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 388] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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Udo de Haes JI, Harada N, Elsinga PH, Maguire RP, Tsukada H. Effect of fenfluramine-induced increases in serotonin release on [18F]MPPF binding: a continuous infusion PET study in conscious monkeys. Synapse 2006; 59:18-26. [PMID: 16237679 DOI: 10.1002/syn.20209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
[(18)F]MPPF is a selective and reversible antagonist to the serotonin-1A (5-HT(1A)) receptor. The aim of the present study was to investigate whether the binding of [(18)F]MPPF is sensitive to increases in 5-HT levels. We used the 5-HT releasing agent and reuptake inhibitor fenfluramine (FEN) to increase the concentration of 5-HT. [(18)F]MPPF binding was assessed using positron emission tomography (PET) in conscious monkeys. Possible effects of blood flow on ligand binding were excluded by using a bolus-infusion paradigm. Control scans were obtained to assess the state of ligand equilibrium. FEN (5 or 10 mg/kg, i.v.) was administered between 90 and 130 min after the start of the [(18)F]MPPF infusion. The binding potential (BP) was calculated for an early interval (30 min preceding FEN administration) and late interval (20-50 min after administration of FEN). Microdialyses results showed a 20- and 35-fold increase in extracellular 5-HT levels in the prefrontal cortex after injection of FEN at a dose of 5 mg/kg and 10 mg/kg respectively. However, despite these large increases in 5-HT levels, no differences in BP were found between the control and FEN scans. These results may imply that the majority of 5-HT(1A) receptors is in the low affinity state in the living brain.
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Affiliation(s)
- Joanna I Udo de Haes
- Department of Biological Psychiatry, University Medical Center Groningen, The Netherlands.
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Kepe V, Barrio JR, Huang SC, Ercoli L, Siddarth P, Shoghi-Jadid K, Cole GM, Satyamurthy N, Cummings JL, Small GW, Phelps ME. Serotonin 1A receptors in the living brain of Alzheimer's disease patients. Proc Natl Acad Sci U S A 2006; 103:702-7. [PMID: 16407119 PMCID: PMC1334681 DOI: 10.1073/pnas.0510237103] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
4-[F-18]fluoro-N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl)benzamide, a selective serotonin 1A (5-HT(1A)) molecular imaging probe, was used in conjunction with positron emission tomography (PET) for quantification of 5-HT(1A) receptor densities in the living brains of Alzheimer's disease patients (ADs) (n = 8), subjects with mild cognitive impairment (n = 6), and controls (n = 5). ADs had receptor densities significantly decreased in both hippocampi (binding potential: controls 1.62 +/- 0.07; ADs 1.18 +/- 0.26) and also in raphe nuclei (controls 0.63 +/- 0.09; ADs 0.37 +/- 0.20). When volume losses are included, 5-HT(1A) losses are even more severe (i.e., average mean decreases of 24% in mild cognitive impairment patients and 49% in ADs). A strong correlation of 5-HT(1A) receptor decreases in hippocampus with worsening of clinical symptoms (Mini Mental State Exam scores) was also found. Moreover, these decreases in 5-HT(1A) receptor measures correlate with decreased glucose utilization as measured with 2-deoxy-2-[F-18]fluoro-d-glucose PET in the brains of ADs (standardized uptake values; globally: controls 0.89 +/- 0.04, ADs 0.72 +/- 0.04; posterior cingulate gyrus: controls 1.05 +/- 0.09, ADs 0.79 +/- 0.11). They also inversely correlate with increased neuropathological loads measured with 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile PET in several neocortical regions in the same subjects. The in vivo observations were confirmed independently by in vitro digital autoradiography with 4-[F-18]fluoro-N-{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}-N-(2-pyridinyl)benzamide and 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}-ethylidene)malononitrile on brain tissue specimens from two ADs and three nondemented subjects.
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Affiliation(s)
- Vladimir Kepe
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Bantick RA, De Vries MH, Grasby PM. The effect of a 5-HT1A receptor agonist on striatal dopamine release. Synapse 2005; 57:67-75. [PMID: 15906386 DOI: 10.1002/syn.20156] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
5-HT1A receptor agonists consistently reduce neuroleptic induced catalepsy in rats. A serotonin-dopamine interaction has been proposed to underlie this effect. Specifically, 5-HT1A receptor agonists may reduce the activity of serotonergic projections that inhibit dopaminergic nigrostriatal neurones, therefore increasing dorsal striatal dopamine levels and partially overcoming the neuroleptic blockade of D2 receptors. We tested the hypothesis that 5-HT1A receptor agonists increase striatal dopamine release in man using PET scanning with the selective D2 receptor radioligand [11C]raclopride, which is sensitive to endogenous dopamine levels. Six healthy volunteers received two PET scans, one after placebo, the other after 1 mg flesinoxan, a selective 5-HT1A receptor agonist. Binding potential values for striatal subdivisions were determined using a simplified reference tissue model. We did not find any difference in striatal [11C]raclopride binding between conditions, even though flesinoxan lead to typical 5-HT1A receptor agonist side effects and produced elevation of growth hormone in five of the six subjects. Our results suggest that the anticataleptic effect of 5-HT1A receptor agonists is not mediated by striatal dopamine release, and indicates a need for further research with other suitable 5-HT1A receptor agonists.
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Affiliation(s)
- R Alexander Bantick
- Cyclotron Unit, CSC, The Hammersmith Hospital, Imperial College London, London W12 0NN, United Kingdom.
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Nagatomo T, Rashid M, Abul Muntasir H, Komiyama T. Functions of 5-HT2A receptor and its antagonists in the cardiovascular system. Pharmacol Ther 2004; 104:59-81. [PMID: 15500909 DOI: 10.1016/j.pharmthera.2004.08.005] [Citation(s) in RCA: 136] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The serotonin (5-hydroxytryptamine, 5-HT) receptors have conventionally been divided into seven subfamilies, most of which have several subtypes. Among them, 5-HT(2A) receptor is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Accordingly, selective 5-HT(2A) antagonists may have potential in the treatment of cardiovascular diseases. Sarpogrelate, a selective 5-HT(2A) antagonist, has been introduced clinically as a therapeutic agent for the treatment of ischemic diseases associated with thrombosis. Molecular modeling studies also suggest that sarpogrelate is a 5-HT(2A) selective antagonist and is likely to have pharmacological effects beneficial in the treatment of cardiovascular diseases. This review describes the above findings as well as the signaling linkages of the 5-HT(2A) receptors and the mode of agonist binding to 5-HT(2A) receptor using data derived from molecular modeling and site-directed mutagenesis.
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Affiliation(s)
- Takafumi Nagatomo
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, 5-13-2 Kamishinei-cho, Niigata 950-2081, Japan.
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