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Thompson SM. Modulators of GABA A receptor-mediated inhibition in the treatment of neuropsychiatric disorders: past, present, and future. Neuropsychopharmacology 2024; 49:83-95. [PMID: 37709943 PMCID: PMC10700661 DOI: 10.1038/s41386-023-01728-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/14/2023] [Accepted: 08/08/2023] [Indexed: 09/16/2023]
Abstract
The predominant inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), acts at ionotropic GABAA receptors to counterbalance excitation and regulate neuronal firing. GABAA receptors are heteropentameric channels comprised from subunits derived from 19 different genes. GABAA receptors have one of the richest and well-developed pharmacologies of any therapeutic drug target, including agonists, antagonists, and positive and negative allosteric modulators (PAMs, NAMs). Currently used PAMs include benzodiazepine sedatives and anxiolytics, barbiturates, endogenous and synthetic neurosteroids, and general anesthetics. In this article, I will review evidence that these drugs act at several distinct binding sites and how they can be used to alter the balance between excitation and inhibition. I will also summarize existing literature regarding (1) evidence that changes in GABAergic inhibition play a causative role in major depression, anxiety, postpartum depression, premenstrual dysphoric disorder, and schizophrenia and (2) whether and how GABAergic drugs exert beneficial effects in these conditions, focusing on human studies where possible. Where these classical therapeutics have failed to exert benefits, I will describe recent advances in clinical and preclinical drug development. I will also highlight opportunities to advance a generation of GABAergic therapeutics, such as development of subunit-selective PAMs and NAMs, that are engendering hope for novel tools to treat these devastating conditions.
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Affiliation(s)
- Scott M Thompson
- Center for Novel Therapeutics, Department of Psychiatry, University of Colorado School of Medicine, 12700 E. 19th Ave., Aurora, CO, 80045, USA.
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2
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Ibrahimy A, Hoye J, Wu H, de Laat B, Kim SJ, Wilson DL, Morris ED. SLIC-Occ: functional segmentation of occupancy images improves precision of EC 50 images. EJNMMI Phys 2023; 10:80. [PMID: 38079001 PMCID: PMC10713928 DOI: 10.1186/s40658-023-00600-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/28/2023] [Indexed: 03/13/2024] Open
Abstract
BACKGROUND Drug occupancy studies with positron emission tomography imaging are used routinely in early phase drug development trials. Recently, our group introduced the Lassen Plot Filter, an extended version of the standard Lassen plot to estimate voxel-level occupancy images. Occupancy images can be used to create an EC50 image by applying an Emax model at each voxel. Our goal was to apply functional clustering of occupancy images via a clustering algorithm and produce a more precise EC50 image while maintaining accuracy. METHOD A digital brain phantom was used to create 10 occupancy images (corresponding to 10 different plasma concentrations of drug) that correspond to a ground truth EC50 image containing two bilateral local "hot spots" of high EC50 (region-1: 25; region-2: 50; background: 6-10 ng/mL). Maximum occupancy was specified as 0.85. An established noise model was applied to the simulated occupancy images and the images were smoothed. Simple Linear Iterative Clustering, an existing k-means clustering algorithm, was modified to segment a series of occupancy images into K clusters (which we call "SLIC-Occ"). EC50 images were estimated by nonlinear estimation at each cluster (post SLIC-Occ) and voxel (no clustering). Coefficient of variation images were estimated at each cluster and voxel, respectively. The same process was also applied to human occupancy data produced for a previously published study. RESULTS Variability in EC50 estimates was reduced by more than 80% in the phantom data after application of SLIC-Occ to occupancy images with only minimal loss of accuracy. A similar, but more modest improvement was achieved in variability when SLIC-Occ was applied to human occupancy images. CONCLUSIONS Our results suggest that functional segmentation of occupancy images via SLIC-Occ could produce more precise EC50 images and improve our ability to identify local "hot spots" of high effective affinity of a drug for its target(s).
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Affiliation(s)
- Alaaddin Ibrahimy
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
| | - Jocelyn Hoye
- Department of Radiology, Yale University, New Haven, CT, USA
| | - Hao Wu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Bart de Laat
- Department of Psychiatry, Yale University, New Haven, CT, USA
| | - Su Jin Kim
- Department of Nuclear Medicine, Seoul National University Budang Hospital, Seongnam, South Korea
| | - David L Wilson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Evan D Morris
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Department of Radiology, Yale University, New Haven, CT, USA
- Department of Psychiatry, Yale University, New Haven, CT, USA
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3
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Kasaragod VB, Malinauskas T, Wahid AA, Lengyel J, Knoflach F, Hardwick SW, Jones CF, Chen WN, Lucas X, El Omari K, Chirgadze DY, Aricescu AR, Cecere G, Hernandez MC, Miller PS. The molecular basis of drug selectivity for α5 subunit-containing GABA A receptors. Nat Struct Mol Biol 2023; 30:1936-1946. [PMID: 37903907 PMCID: PMC10716045 DOI: 10.1038/s41594-023-01133-1] [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: 02/28/2023] [Accepted: 09/20/2023] [Indexed: 11/01/2023]
Abstract
α5 subunit-containing γ-aminobutyric acid type A (GABAA) receptors represent a promising drug target for neurological and neuropsychiatric disorders. Altered expression and function contributes to neurodevelopmental disorders such as Dup15q and Angelman syndromes, developmental epilepsy and autism. Effective drug action without side effects is dependent on both α5-subtype selectivity and the strength of the positive or negative allosteric modulation (PAM or NAM). Here we solve structures of drugs bound to the α5 subunit. These define the molecular basis of binding and α5 selectivity of the β-carboline, methyl 6,7-dimethoxy-4-ethyl-β-carboline-3-carboxylate (DMCM), type II benzodiazepine NAMs, and a series of isoxazole NAMs and PAMs. For the isoxazole series, each molecule appears as an 'upper' and 'lower' moiety in the pocket. Structural data and radioligand binding data reveal a positional displacement of the upper moiety containing the isoxazole between the NAMs and PAMs. Using a hybrid molecule we directly measure the functional contribution of the upper moiety to NAM versus PAM activity. Overall, these structures provide a framework by which to understand distinct modulator binding modes and their basis of α5-subtype selectivity, appreciate structure-activity relationships, and empower future structure-based drug design campaigns.
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Affiliation(s)
- Vikram Babu Kasaragod
- Department of Pharmacology, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Tomas Malinauskas
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ayla A Wahid
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Judith Lengyel
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland
| | - Frederic Knoflach
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland
| | - Steven W Hardwick
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | | | - Wan-Na Chen
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Xavier Lucas
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center, Basel, Switzerland
| | - Kamel El Omari
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Dimitri Y Chirgadze
- CryoEM Facility, Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - A Radu Aricescu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Giuseppe Cecere
- Roche Pharma Research and Early Development, Therapeutic Modalities, Roche Innovation Center, Basel, Switzerland
| | - Maria-Clemencia Hernandez
- Roche Pharma Research and Early Development, Neuroscience and Rare Diseases, Roche Innovation Center, Basel, Switzerland.
| | - Paul S Miller
- Department of Pharmacology, University of Cambridge, Cambridge, UK.
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4
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Wang X, Wang T, Fan X, Zhang Z, Wang Y, Li Z. A Molecular Toolbox of Positron Emission Tomography Tracers for General Anesthesia Mechanism Research. J Med Chem 2023; 66:6463-6497. [PMID: 37145921 DOI: 10.1021/acs.jmedchem.2c01965] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
With appropriate radiotracers, positron emission tomography (PET) allows direct or indirect monitoring of the spatial and temporal distribution of anesthetics, neurotransmitters, and biomarkers, making it an indispensable tool for studying the general anesthesia mechanism. In this Perspective, PET tracers that have been recruited in general anesthesia research are introduced in the following order: 1) 11C/18F-labeled anesthetics, i.e., PET tracers made from inhaled and intravenous anesthetics; 2) PET tracers targeting anesthesia-related receptors, e.g., neurotransmitters and voltage-gated ion channels; and 3) PET tracers for studying anesthesia-related neurophysiological effects and neurotoxicity. The radiosynthesis, pharmacodynamics, and pharmacokinetics of the above PET tracers are mainly discussed to provide a practical molecular toolbox for radiochemists, anesthesiologists, and those who are interested in general anesthesia.
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Affiliation(s)
- Xiaoxiao Wang
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Tao Wang
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Xiaowei Fan
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Zhao Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Yingwei Wang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Zijing Li
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
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Kiemes A, Serrano Navacerrada ME, Kim E, Randall K, Simmons C, Rojo Gonzalez L, Petrinovic MM, Lythgoe DJ, Rotaru D, Di Censo D, Hirschler L, Barbier EL, Vernon AC, Stone JM, Davies C, Cash D, Modinos G. Erbb4 Deletion From Inhibitory Interneurons Causes Psychosis-Relevant Neuroimaging Phenotypes. Schizophr Bull 2023; 49:569-580. [PMID: 36573631 PMCID: PMC10154722 DOI: 10.1093/schbul/sbac192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND HYPOTHESIS Converging lines of evidence suggest that dysfunction of cortical GABAergic inhibitory interneurons is a core feature of psychosis. This dysfunction is thought to underlie neuroimaging abnormalities commonly found in patients with psychosis, particularly in the hippocampus. These include increases in resting cerebral blood flow (CBF) and glutamatergic metabolite levels, and decreases in ligand binding to GABAA α5 receptors and to the synaptic density marker synaptic vesicle glycoprotein 2A (SV2A). However, direct links between inhibitory interneuron dysfunction and these neuroimaging readouts are yet to be established. Conditional deletion of a schizophrenia susceptibility gene, the tyrosine kinase receptor Erbb4, from cortical and hippocampal inhibitory interneurons leads to synaptic defects, and behavioral and cognitive phenotypes relevant to psychosis in mice. STUDY DESIGN Here, we investigated how this inhibitory interneuron disruption affects hippocampal in vivo neuroimaging readouts. Adult Erbb4 conditional mutant mice (Lhx6-Cre;Erbb4F/F, n = 12) and their wild-type littermates (Erbb4F/F, n = 12) were scanned in a 9.4T magnetic resonance scanner to quantify CBF and glutamatergic metabolite levels (glutamine, glutamate, GABA). Subsequently, we assessed GABAA receptors and SV2A density using quantitative autoradiography. RESULTS Erbb4 mutant mice showed significantly elevated ventral hippccampus CBF and glutamine levels, and decreased SV2A density across hippocampus sub-regions compared to wild-type littermates. No significant GABAA receptor density differences were identified. CONCLUSIONS These findings demonstrate that specific disruption of cortical inhibitory interneurons in mice recapitulate some of the key neuroimaging findings in patients with psychosis, and link inhibitory interneuron deficits to non-invasive measures of brain function and neurochemistry that can be used across species.
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Affiliation(s)
- Amanda Kiemes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Maria Elisa Serrano Navacerrada
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Eugene Kim
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Karen Randall
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Camilla Simmons
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Loreto Rojo Gonzalez
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Marija-Magdalena Petrinovic
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, UK
- Department of Forensic and Neurodevelopmental Science, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - David J Lythgoe
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Diana Rotaru
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Davide Di Censo
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
- Department of Psychology, University of Cambridge, Cambridge, UK
| | - Lydiane Hirschler
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, Grenoble, France
| | - Emmanuel L Barbier
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, Grenoble, France
| | - Anthony C Vernon
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, UK
- Department of Basic and Clinical Neuroscience, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - James M Stone
- Brighton and Sussex Medical School, University of Sussex, Brighton, UK
| | - Cathy Davies
- Department of Psychosis Studies, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Diana Cash
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
| | - Gemma Modinos
- Department of Psychosis Studies, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
- Department of Neuroimaging, School of Neuroscience, Institute of Psychiatry, Psychology, and Neuroscience, King’s College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King’s College London, London, UK
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6
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Lukow PB, Martins D, Veronese M, Vernon AC, McGuire P, Turkheimer FE, Modinos G. Cellular and molecular signatures of in vivo imaging measures of GABAergic neurotransmission in the human brain. Commun Biol 2022; 5:372. [PMID: 35440709 PMCID: PMC9018713 DOI: 10.1038/s42003-022-03268-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 03/14/2022] [Indexed: 11/21/2022] Open
Abstract
Diverse GABAergic interneuron networks orchestrate information processing in the brain. Understanding the principles underlying the organisation of this system in the human brain, and whether these principles are reflected by available non-invasive in vivo neuroimaging methods, is crucial for the study of GABAergic neurotransmission. Here, we use human gene expression data and state-of-the-art imaging transcriptomics to uncover co-expression patterns between genes encoding GABAA receptor subunits and inhibitory interneuron subtype-specific markers, and their association with binding patterns of the gold-standard GABA PET radiotracers [11C]Ro15-4513 and [11C]flumazenil. We found that the inhibitory interneuron marker somatostatin covaries with GABAA receptor-subunit genes GABRA5 and GABRA2, and that their distribution followed [11C]Ro15-4513 binding. In contrast, the inhibitory interneuron marker parvalbumin covaried with GABAA receptor-subunit genes GABRA1, GABRB2 and GABRG2, and their distribution tracked [11C]flumazenil binding. Our findings indicate that existing PET radiotracers may provide complementary information about key components of the GABAergic system.
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Affiliation(s)
- Paulina Barbara Lukow
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK.
| | - Daniel Martins
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
- NIHR Maudsley Biomedical Research Centre, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK
| | - Mattia Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
- NIHR Maudsley Biomedical Research Centre, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK
- Department of Information Engineering, University of Padua, Via Giovanni Gradenigo, 6, 35131, Padova, PD, Italy
| | - Anthony Christopher Vernon
- Department of Basic & Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, 5 Cutcombe Road, Brixton, London, SE5 9RT, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, New Hunt's House, Guy's Campus, London, UK
| | - Philip McGuire
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
- NIHR Maudsley Biomedical Research Centre, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK
| | - Federico Edoardo Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
| | - Gemma Modinos
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, SE5 8AF, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, New Hunt's House, Guy's Campus, London, UK
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7
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Kiemes A, Gomes FV, Cash D, Uliana DL, Simmons C, Singh N, Vernon AC, Turkheimer F, Davies C, Stone JM, Grace AA, Modinos G. GABA A and NMDA receptor density alterations and their behavioral correlates in the gestational methylazoxymethanol acetate model for schizophrenia. Neuropsychopharmacology 2022; 47:687-695. [PMID: 34743200 PMCID: PMC8782908 DOI: 10.1038/s41386-021-01213-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/09/2021] [Accepted: 10/13/2021] [Indexed: 01/19/2023]
Abstract
Hippocampal hyperactivity driven by GABAergic interneuron deficits and NMDA receptor hypofunction is associated with the hyperdopaminergic state often observed in schizophrenia. Furthermore, previous research in the methylazoxymethanol acetate (MAM) rat model has demonstrated that repeated peripubertal diazepam administration can prevent the emergence of adult hippocampal hyperactivity, dopamine-system hyperactivity, and associated psychosis-relevant behaviors. Here, we sought to characterize hippocampal GABAA and NMDA receptors in MAM-treated rats and to elucidate the receptor mechanisms underlying the promising effects of peripubertal diazepam exposure. Quantitative receptor autoradiography was used to measure receptor density in the dorsal hippocampus CA1, ventral hippocampus CA1, and ventral subiculum. Specifically, [3H]-Ro15-4513 was used to quantify the density of α5GABAA receptors (α5GABAAR), [3H]-flumazenil to quantify α1-3;5GABAAR, and [3H]-MK801 to quantify NMDA receptors. MAM rats exhibited anxiety and schizophrenia-relevant behaviors as measured by elevated plus maze and amphetamine-induced hyperlocomotion (AIH), although diazepam only partially rescued these behaviors. α5GABAAR density was reduced in MAM-treated rats in all hippocampal sub-regions, and negatively correlated with AIH. Ventral hippocampus CA1 α5GABAAR density was positively correlated with anxiety-like behavior. Dorsal hippocampus CA1 NMDA receptor density was increased in MAM-treated rats, and positively correlated with AIH. [3H]-flumazenil revealed no significant effects. Finally, we found no significant effect of diazepam treatment on receptor densities, potentially related to the only partial rescue of schizophrenia-relevant phenotypes. Overall, our findings provide first evidence of α5GABAAR and NMDA receptor abnormalities in the MAM model, suggesting that more selective pharmacological agents may become a novel therapeutic mechanism in schizophrenia.
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Affiliation(s)
- Amanda Kiemes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
| | - Felipe V Gomes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Diana Cash
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Daniela L Uliana
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Camilla Simmons
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Nisha Singh
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
| | - Anthony C Vernon
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
| | - Federico Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Cathy Davies
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - James M Stone
- Brighton and Sussex Medical School, University of Sussex, Brighton, UK
| | - Anthony A Grace
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Gemma Modinos
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, UK
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8
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Sperk G, Pirker S, Gasser E, Wieselthaler A, Bukovac A, Kuchukhidze G, Maier H, Drexel M, Baumgartner C, Ortler M, Czech T. Increased expression of GABA A receptor subunits associated with tonic inhibition in patients with temporal lobe epilepsy. Brain Commun 2021; 3:fcab239. [PMID: 34708207 PMCID: PMC8545616 DOI: 10.1093/braincomms/fcab239] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/07/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022] Open
Abstract
Epilepsy animal models indicate pronounced changes in the expression and rearrangement of GABAA receptor subunits in the hippocampus and in para-hippocampal areas, including widespread downregulation of the subunits α5 and δ, and upregulation of α4, subunits that mediate tonic inhibition of GABA. In this case–control study, we investigated changes in the expression of subunits α4, α5 and δ in hippocampal specimens of drug resistant temporal lobe epilepsy patients who underwent epilepsy surgery. Using in situ hybridization, immunohistochemistry and α5-specific receptor autoradiography, we characterized expression of the receptor subunits in specimens from patients with and without Ammon’s horn sclerosis compared to post-mortem controls. Expression of the α5-subunit was abundant throughout all subfields of the hippocampus, including the dentate gyrus, sectors CA1 and CA3, the subiculum and pre- and parasubiculum. Significant but weaker expression was detected for subunits α4 and δ notably in the granule cell/molecular layer of control specimens, but was faint in the other parts of the hippocampus. Expression of all three subunits was similarly altered in sclerotic and non-sclerotic specimens. Respective mRNA levels were increased by about 50–80% in the granule cell layer compared with post-mortem controls. Subunit α5 mRNA levels and immunoreactivities were also increased in the sector CA3 and in the subiculum. Autoradiography for α5-containing receptors using [3H]L-655,708 as ligand showed significantly increased binding in the molecular layer of the dentate gyrus in non-sclerotic specimens. Increased expression of the α5 and δ subunits is in contrast to the previously observed downregulation of these subunits in different epilepsy models, whereas increased expression of α4 in temporal lobe epilepsy patients is consistent with that in the rodent models. Our findings indicate increased tonic inhibition likely representing an endogenous anticonvulsive mechanism in temporal lobe epilepsy.
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Affiliation(s)
- Günther Sperk
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Susanne Pirker
- Neurological Department, Klinik Hietzing, 1130 Vienna, Austria
| | - Elisabeth Gasser
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anna Wieselthaler
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anneliese Bukovac
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Giorgi Kuchukhidze
- Department of Neurology, Christian Doppler Klinik, Affiliated Member of the European Reference Network EpiCARE and Centre for Cognitive Neuroscience, Paracelsus Medical University of Salzburg, 5020 Salzburg, Austria.,Neuroscience Institute, Christian Doppler Klinik, 5020 Salzburg, Austria
| | - Hans Maier
- INNPATH GmbH-Institute of Pathology, 6020 Innsbruck, Austria
| | - Meinrad Drexel
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria.,Institute of Molecular and Cellular Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | | | - Marin Ortler
- Department of Neurosurgery, Klinik Landstrasse, Vienna Healthcare Network, 1030Vienna, Austria.,Department of Neurosurgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Thomas Czech
- Department of Neurosurgery, Medical University Vienna, 1090 Vienna, Austria
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9
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de Laat B, Hoye J, Liu H, Morris ED. EC 50 images, a novel endpoint from PET target occupancy studies, reveal spatial variation in apparent drug affinity. Eur J Nucl Med Mol Imaging 2021; 49:1232-1241. [PMID: 34636937 DOI: 10.1007/s00259-021-05561-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/06/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE We recently introduced voxel-level images of drug occupancy from PET via our "Lassen plot filter." Occupancy images revealed clear dependence of 11C-flumazenil displacement on dose of GABAa inhibitor, CVL-865, but with different scales in different brain regions. We hypothesized that regions requiring higher drug concentrations to achieve desired occupancy would have higher EC50 values. We introduce an "EC50 image" from human data to evaluate this hypothesis. METHODS Five healthy subjects were scanned with the nonselective GABAa tracer, 11C-flumazenil, before and (twice) after administration of CVL-865. We created ten occupancy images and applied an Emax model locally to create one EC50 image. We also performed simulations to confirm our observations of regional variation in EC50 and to identify the main source of variability in EC50. RESULTS As expected, the EC50 image revealed spatial variation in apparent drug affinity. High EC50 was found in areas of low occupancy for a given drug dose. Simulations demonstrated that sampling from an inadequate range of plasma drug concentrations could impair precision. CONCLUSION Our results argue for (a) confidence in the ability of the EC50 images to identify regional differences and (b) a need to tailor the range of drug doses in an occupancy study to regularize the precision of the EC50 throughout the brain. The EC50 image could add value to early-phase drug development by identifying regional variation in affinity that might impact therapy or safety and by guiding dose selection for later-phase trials.
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Affiliation(s)
- Bart de Laat
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Jocelyn Hoye
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Heather Liu
- Department of Biomedical Engineering, Yale University, CT, New Haven, USA
| | - Evan D Morris
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA.
- Department of Psychiatry, Yale University, New Haven, CT, USA.
- Department of Biomedical Engineering, Yale University, CT, New Haven, USA.
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10
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de Laat B, Morris ED. A local-neighborhood Lassen plot filter for creating occupancy and non-displaceable binding images. J Cereb Blood Flow Metab 2021; 41:1379-1389. [PMID: 33050827 PMCID: PMC8142134 DOI: 10.1177/0271678x20950486] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
For radioligands without a reference region, the Lassen plot can be used to estimate receptor occupancy by an exogenous drug (ODrug). However, the Lassen plot is not well-suited for spatial variation in ODrug. To overcome this limitation, we introduce a Lassen plot filter, i.e. a Lassen plot applied to local neighborhoods in PET images. Image data were simulated with regional variation in VND, ODrug, both, or neither and analyzed using the change in binding potential (ΔBPND), the conventional Lassen plot, and the Lassen plot filter at the region of interest (ROI) and voxel level. All methods were also applied to a human [11C]flumazenil occupancy study using PF-06372865. This combination of a non-selective radioligand and selective drug should lead to varying ODrug provided the distribution of subtypes varies spatially. In contrast with ΔBPND and the conventional Lassen plot, ROI-level and voxel-level Lassen plot filter estimates remained unbiased in the presence of regional variation in VND or ODrug. In the [11C]flumazenil data-set, ODrug was shown to vary regionally in accordance with the distribution of binding sites for [11C]flumazenil and PF-06372865. We demonstrate that a local-neighborhood Lassen plot filter provides robust and unbiased estimates of ODrug and VND without the need for any user intervention.
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Affiliation(s)
- Bart de Laat
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Evan D Morris
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA.,Department of Psychiatry, Yale University, New Haven, CT, USA.,Department of Biomedical Engineering, Yale University, New Haven, CT, USA.,Invicro, LLC, New Haven, CT, USA
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11
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Basmisanil, a highly selective GABA A-α5 negative allosteric modulator: preclinical pharmacology and demonstration of functional target engagement in man. Sci Rep 2021; 11:7700. [PMID: 33833333 PMCID: PMC8032764 DOI: 10.1038/s41598-021-87307-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 03/26/2021] [Indexed: 12/21/2022] Open
Abstract
GABAA-α5 subunit-containing receptors have been shown to play a key modulatory role in cognition and represent a promising drug target for cognitive dysfunction, as well as other disorders. Here we report on the preclinical and early clinical profile of a novel GABAA-α5 selective negative allosteric modulator (NAM), basmisanil, which progressed into Phase II trials for intellectual disability in Down syndrome and cognitive impairment associated with schizophrenia. Preclinical pharmacology studies showed that basmisanil is the most selective GABAA-α5 receptor NAM described so far. Basmisanil bound to recombinant human GABAA-α5 receptors with 5 nM affinity and more than 90-fold selectivity versus α1, α2, and α3 subunit-containing receptors. Moreover, basmisanil inhibited GABA-induced currents at GABAA-α5 yet had little or no effect at the other receptor subtypes. An in vivo occupancy study in rats showed dose-dependent target engagement and was utilized to establish the plasma exposure to receptor occupancy relationship. At estimated receptor occupancies between 30 and 65% basmisanil attenuated diazepam-induced spatial learning impairment in rats (Morris water maze), improved executive function in non-human primates (object retrieval), without showing anxiogenic or proconvulsant effects in rats. During the Phase I open-label studies, basmisanil showed good safety and tolerability in healthy volunteers at maximum GABAA-α5 receptor occupancy as confirmed by PET analysis with the tracer [11C]-Ro 15-4513. An exploratory EEG study provided evidence for functional activity of basmisanil in human brain. Therefore, these preclinical and early clinical studies show that basmisanil has an ideal profile to investigate potential clinical benefits of GABAA-α5 receptor negative modulation.
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12
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Goud NS, Bhattacharya A, Joshi RK, Nagaraj C, Bharath RD, Kumar P. Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology. J Med Chem 2021; 64:1223-1259. [PMID: 33499603 DOI: 10.1021/acs.jmedchem.0c01053] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Ahana Bhattacharya
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Raman Kumar Joshi
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
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13
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McGinnity CJ, Riaño Barros DA, Hinz R, Myers JF, Yaakub SN, Thyssen C, Heckemann RA, de Tisi J, Duncan JS, Sander JW, Lingford-Hughes A, Koepp MJ, Hammers A. Αlpha 5 subunit-containing GABA A receptors in temporal lobe epilepsy with normal MRI. Brain Commun 2021; 3:fcaa190. [PMID: 33501420 PMCID: PMC7811756 DOI: 10.1093/braincomms/fcaa190] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 09/06/2020] [Accepted: 09/24/2020] [Indexed: 01/08/2023] Open
Abstract
GABAA receptors containing the α5 subunit mediate tonic inhibition and are widely expressed in the limbic system. In animals, activation of α5-containing receptors impairs hippocampus-dependent memory. Temporal lobe epilepsy is associated with memory impairments related to neuron loss and other changes. The less selective PET ligand [11C]flumazenil has revealed reductions in GABAA receptors. The hypothesis that α5 subunit receptor alterations are present in temporal lobe epilepsy and could contribute to impaired memory is untested. We compared α5 subunit availability between individuals with temporal lobe epilepsy and normal structural MRI ('MRI-negative') and healthy controls, and interrogated the relationship between α5 subunit availability and episodic memory performance, in a cross-sectional study. Twenty-three healthy male controls (median ± interquartile age 49 ± 13 years) and 11 individuals with MRI-negative temporal lobe epilepsy (seven males; 40 ± 8) had a 90-min PET scan after bolus injection of [11C]Ro15-4513, with arterial blood sampling and metabolite correction. All those with epilepsy and six controls completed the Adult Memory and Information Processing Battery on the scanning day. 'Bandpass' exponential spectral analyses were used to calculate volumes of distribution separately for the fast component [V F; dominated by signal from α1 (α2, α3)-containing receptors] and the slow component (V S; dominated by signal from α5-containing receptors). We made voxel-by-voxel comparisons between: the epilepsy and control groups; each individual case versus the controls. We obtained parametric maps of V F and V S measures from a single bolus injection of [11C]Ro15-4513. The epilepsy group had higher V S in anterior medial and lateral aspects of the temporal lobes, the anterior cingulate gyri, the presumed area tempestas (piriform cortex) and the insulae, in addition to increases of ∼24% and ∼26% in the ipsilateral and contralateral hippocampal areas (P < 0.004). This was associated with reduced V F:V S ratios within the same areas (P < 0.009). Comparisons of V S for each individual with epilepsy versus controls did not consistently lateralize the epileptogenic lobe. Memory scores were significantly lower in the epilepsy group than in controls (mean ± standard deviation -0.4 ± 1.0 versus 0.7 ± 0.3; P = 0.02). In individuals with epilepsy, hippocampal V S did not correlate with memory performance on the Adult Memory and Information Processing Battery. They had reduced V F in the hippocampal area, which was significant ipsilaterally (P = 0.03), as expected from [11C]flumazenil studies. We found increased tonic inhibitory neurotransmission in our cohort of MRI-negative temporal lobe epilepsy who also had co-morbid memory impairments. Our findings are consistent with a subunit shift from α1/2/3 to α5 in MRI-negative temporal lobe epilepsy.
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Affiliation(s)
- Colm J McGinnity
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Daniela A Riaño Barros
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
| | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester M20 3LJ, UK
| | - James F Myers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Siti N Yaakub
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Charlotte Thyssen
- Medical Image and Signal Processing (MEDISIP), Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, 9000 Ghent, Belgium
| | - Rolf A Heckemann
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Jane de Tisi
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - John S Duncan
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede 2103SW, The Netherlands
| | - Anne Lingford-Hughes
- Neuropsychopharmacology Unit, Centre for Psychiatry, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London W12 0NN, UK
| | - Matthias J Koepp
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Alexander Hammers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
- Neurodis Foundation, CERMEP, Imagerie du Vivant, 69003 Lyon, France
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14
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Marques TR, Ashok AH, Angelescu I, Borgan F, Myers J, Lingford-Hughes A, Nutt DJ, Veronese M, Turkheimer FE, Howes OD. GABA-A receptor differences in schizophrenia: a positron emission tomography study using [ 11C]Ro154513. Mol Psychiatry 2021; 26:2616-2625. [PMID: 32296127 PMCID: PMC8440185 DOI: 10.1038/s41380-020-0711-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/17/2020] [Accepted: 03/04/2020] [Indexed: 01/28/2023]
Abstract
A loss of GABA signaling is a prevailing hypothesis for the pathogenesis of schizophrenia. Preclinical studies indicate that blockade of the α5 subtype of the GABA receptor (α5-GABAARs) leads to behavioral phenotypes associated with schizophrenia, and postmortem evidence indicates lower hippocampal α5-GABAARs protein and mRNA levels in schizophrenia. However, it is unclear if α5-GABAARs are altered in vivo or related to symptoms. We investigated α5-GABAARs availability in antipsychotic-free schizophrenia patients and antipsychotic-medicated schizophrenia patients using [11C]Ro15-4513 PET imaging in a cross-sectional, case-control study design. Thirty-one schizophrenia patients (n = 10 antipsychotic free) and twenty-nine matched healthy controls underwent a [11C]Ro15-4513 PET scan and MRI. The α5 subtype GABA-A receptor availability was indexed using [11C]Ro15-4513 PET imaging. Dynamic PET data were analyzed using the two-tissue compartment model with an arterial plasma input function and total volume of distribution (VT) as the outcome measure. Symptom severity was assessed using the PANSS scale. There was significantly lower [11C]Ro15-4513 VT in the hippocampus of antipsychotic-free patients, but not in medicated patients (p = 0.64), relative to healthy controls (p < 0.05; effect size = 1.4). There was also a significant positive correlation between [11C]Ro15-4513 VT and total PANSS score in antipsychotic-free patients (r = 0.72; p = 0.044). The results suggest that antipsychotic-free patients with schizophrenia have lower α5-GABAARs levels in the hippocampus, consistent with the hypothesis that GABA hypofunction underlies the pathophysiology of the disorder.
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Affiliation(s)
- Tiago Reis Marques
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, London, UK. .,Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
| | - Abhishekh H. Ashok
- grid.14105.310000000122478951Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, London, UK ,grid.13097.3c0000 0001 2322 6764Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Ilinca Angelescu
- grid.13097.3c0000 0001 2322 6764Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Faith Borgan
- grid.14105.310000000122478951Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, London, UK ,grid.13097.3c0000 0001 2322 6764Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Jim Myers
- grid.7445.20000 0001 2113 8111Faculty of Medicine, Imperial College London, London, UK
| | - Anne Lingford-Hughes
- grid.7445.20000 0001 2113 8111Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, London, UK
| | - David J. Nutt
- grid.7445.20000 0001 2113 8111Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, London, UK
| | - Mattia Veronese
- grid.13097.3c0000 0001 2322 6764Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Federico E. Turkheimer
- grid.13097.3c0000 0001 2322 6764Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
| | - Oliver D. Howes
- grid.14105.310000000122478951Psychiatric Imaging Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, London, UK ,grid.13097.3c0000 0001 2322 6764Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
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15
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Peris-Yague A, Kiemes A, Cash D, Cotel MC, Singh N, Vernon AC, Modinos G. Region-specific and dose-specific effects of chronic haloperidol exposure on [ 3H]-flumazenil and [ 3H]-Ro15-4513 GABA A receptor binding sites in the rat brain. Eur Neuropsychopharmacol 2020; 41:106-117. [PMID: 33153853 PMCID: PMC7731940 DOI: 10.1016/j.euroneuro.2020.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 09/02/2020] [Accepted: 10/16/2020] [Indexed: 11/02/2022]
Abstract
Postmortem studies suggest that schizophrenia is associated with abnormal expression of specific GABAA receptor (GABAAR) α subunits, including α5GABAAR. Positron emission tomography (PET) measures of GABAAR availability in schizophrenia, however, have not revealed consistent alterations in vivo. Animal studies using the GABAAR agonist [3H]-muscimol provide evidence that antipsychotic drugs influence GABAAR availability, in a region-specific manner, suggesting a potential confounding effect of these drugs. No such data, however, are available for more recently developed subunit-selective GABAAR radioligands. To address this, we combined a rat model of clinically relevant antipsychotic drug exposure with quantitative receptor autoradiography. Haloperidol (0.5 and 2 mg/kg/day) or drug vehicle were administered continuously to adult male Sprague-Dawley rats via osmotic mini-pumps for 28 days. Quantitative receptor autoradiography was then performed postmortem using the GABAAR subunit-selective radioligand [3H]-Ro15-4513 and the non-subunit selective radioligand [3H]-flumazenil. Chronic haloperidol exposure increased [3H]-Ro15-4513 binding in the CA1 sub-field of the rat dorsal hippocampus (p<0.01; q<0.01; d=+1.3), which was not dose-dependent. [3H]-flumazenil binding also increased in most rat brain regions (p<0.05; main effect of treatment), irrespective of the haloperidol dose. These data confirm previous findings that chronic haloperidol exposure influences the specific binding of non-subtype selective GABAAR radioligands and is the first to demonstrate a potential effect of haloperidol on the binding of a α1/5GABAAR-selective radioligand. Although caution should be exerted when extrapolating results from animals to patients, our data support a view that exposure to antipsychotics may be a confounding factor in PET studies of GABAAR in the context of schizophrenia.
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Affiliation(s)
- Alba Peris-Yague
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom
| | - Amanda Kiemes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespingy Park, London SE5 8AF, United Kingdom
| | - Diana Cash
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom
| | - Marie-Caroline Cotel
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, 5 Cutcombe Road, London SE5 9RT, United Kingdom
| | - Nisha Singh
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom
| | - Anthony C Vernon
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, 5 Cutcombe Road, London SE5 9RT, United Kingdom; MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom.
| | - Gemma Modinos
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, United Kingdom; Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespingy Park, London SE5 8AF, United Kingdom; MRC Centre for Neurodevelopmental Disorders, King's College London, London, United Kingdom.
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16
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Janeczek P, Colson N, Dodd PR, Lewohl JM. Sex Differences in the Expression of the α5 Subunit of the GABA A Receptor in Alcoholics with and without Cirrhosis of the Liver. Alcohol Clin Exp Res 2020; 44:423-434. [PMID: 31840824 DOI: 10.1111/acer.14266] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 12/02/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND Alcohol exposure alters the expression of a large number of genes, resulting in neuronal adaptions and neuronal loss, but the underlying mechanisms are largely unknown. miRNAs are gene repressors that are abundant in the brain. A recent study identified ~ 35 miRNAs that are up-regulated in the prefrontal cortex of human alcoholics and predicted to target genes that are down-regulated in the same region. Although interactions between alcohol-responsive miRNAs and their target genes have been predicted, few studies have validated these predictions. METHODS We measured the expression of GABAA α5 mRNA in the prefrontal and motor cortices of human alcoholics and matched controls using real-time PCR. The expression of miR-203 was measured in a subset of these cases. The predicted interaction of miR-203 and GABRA5 was validated for miR-203 using a luciferase reporter assay. RESULTS In both frontal and motor cortices, the expression of GABAA α5 was significantly lower in cirrhotic alcoholics compared with controls. Further, the pattern of expression between the groups was significantly different between males and females. The expression of miR-203 was higher in the prefrontal cortex of cirrhotic alcoholics compared with controls and uncomplicated alcoholics. These differences were particularly marked in female cases. Cotransfection of GABRA5 with miR-203 in HEK293T cells reduced luciferase reporter activity. CONCLUSION There are sex differences in the expression of GABAA α5 and miR-203 in the brain of human alcoholics which are particularly marked in alcoholics with cirrhosis of the liver. Further, miR-203 may mediate the changes in expression of this GABAA receptor isoform that is brought about by alcohol exposure.
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Affiliation(s)
- Paulina Janeczek
- From the, School of Medical Science, (PJ, NC, JML), Griffith University Gold Coast campus, Southport, Queensland, Australia
| | - Natalie Colson
- From the, School of Medical Science, (PJ, NC, JML), Griffith University Gold Coast campus, Southport, Queensland, Australia
| | - Peter R Dodd
- School of Chemistry and Molecular Biosciences, (PRD), The University of Queensland St Lucia campus, Brisbane, Queensland, Australia
| | - Joanne M Lewohl
- From the, School of Medical Science, (PJ, NC, JML), Griffith University Gold Coast campus, Southport, Queensland, Australia
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17
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Gobbi L, Mercier J, Bang-Andersen B, Nicolas JM, Reilly J, Wagner B, Whitehead D, Briard E, Maguire RP, Borroni E, Auberson YP. A Comparative Study of in vitro Assays for Predicting the Nonspecific Binding of PET Imaging Agents in vivo. ChemMedChem 2019; 15:585-592. [PMID: 31797561 DOI: 10.1002/cmdc.201900608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/27/2019] [Indexed: 01/23/2023]
Abstract
Nonspecific binding (NSB) is a key parameter in optimizing PET imaging tracers. We compared the ability to predict NSB of three available methods: LIMBA, rat fu,brain , and CHI(IAM). Even though NSB is often associated with lipophilicity, we observed that logD does not correlate with any of these assays, clearly indicating that lipophilicity, while influencing NSB, is insufficient to predict it. A cross-comparison of the methods showed that all three correlate and are useful predictors of NSB. The three assays, however, rank the molecules slightly differently, illustrating the challenge of comparing molecules within a narrow chemical space. We also noted that CHI(IAM) values more effectively predict VNS , a measure of in vivo NSB in the human brain. CHI(IAM) measurements might be a closer model of the actual physicochemical interaction between PET tracer candidates and cell membranes, and seems to be the method of choice for the optimization of in vivo NSB.
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Affiliation(s)
- Luca Gobbi
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Joël Mercier
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Benny Bang-Andersen
- Molecular Discovery and Innovation, H. Lundbeck A/S, 9 Ottiliavej, 2500, Valby, Denmark
| | | | - John Reilly
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Björn Wagner
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - David Whitehead
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - Emmanuelle Briard
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
| | - R Paul Maguire
- UCB Early Solutions, UCB Biopharma sprl, 1420, Braine-l'Alleud, Belgium
| | - Edilio Borroni
- Pharma Research and Early Development, Roche Innovation Center Basel F. Hoffmann-La Roche Ltd., 4070, Basel, Switzerland
| | - Yves P Auberson
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Fabrikstrasse 2, 4056, Basel, Switzerland
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Frohlich J, Reiter LT, Saravanapandian V, DiStefano C, Huberty S, Hyde C, Chamberlain S, Bearden CE, Golshani P, Irimia A, Olsen RW, Hipp JF, Jeste SS. Mechanisms underlying the EEG biomarker in Dup15q syndrome. Mol Autism 2019; 10:29. [PMID: 31312421 PMCID: PMC6609401 DOI: 10.1186/s13229-019-0280-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/11/2019] [Indexed: 12/11/2022] Open
Abstract
Background Duplications of 15q11.2-q13.1 (Dup15q syndrome), including the paternally imprinted gene UBE3A and three nonimprinted gamma-aminobutyric acid type-A (GABAA) receptor genes, are highly penetrant for neurodevelopmental disorders such as autism spectrum disorder (ASD). To guide targeted treatments of Dup15q syndrome and other forms of ASD, biomarkers are needed that reflect molecular mechanisms of pathology. We recently described a beta EEG phenotype of Dup15q syndrome, but it remains unknown which specific genes drive this phenotype. Methods To test the hypothesis that UBE3A overexpression is not necessary for the beta EEG phenotype, we compared EEG from a reference cohort of children with Dup15q syndrome (n = 27) to (1) the pharmacological effects of the GABAA modulator midazolam (n = 12) on EEG from healthy adults, (2) EEG from typically developing (TD) children (n = 14), and (3) EEG from two children with duplications of paternal 15q (i.e., the UBE3A-silenced allele). Results Peak beta power was significantly increased in the reference cohort relative to TD controls. Midazolam administration recapitulated the beta EEG phenotype in healthy adults with a similar peak frequency in central channels (f = 23.0 Hz) as Dup15q syndrome (f = 23.1 Hz). Both paternal Dup15q syndrome cases displayed beta power comparable to the reference cohort. Conclusions Our results suggest a critical role for GABAergic transmission in the Dup15q syndrome beta EEG phenotype, which cannot be explained by UBE3A dysfunction alone. If this mechanism is confirmed, the phenotype may be used as a marker of GABAergic pathology in clinical trials for Dup15q syndrome.
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Affiliation(s)
- Joel Frohlich
- Roche Pharma Research and Early Development, Neuroscience, Ophthalmology and Rare Diseases, Roche Innovation Center Basel, Basel, Switzerland
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
- Department of Psychology, University of California Los Angeles, 3423 Franz Hall, Los Angeles, CA 90095 USA
| | - Lawrence T. Reiter
- Departments of Neurology, Pediatrics and Anatomy & Neurobiology, The University of Tennessee Health Science Center, 855 Monroe Ave., Link, Memphis, TN 415 USA
| | - Vidya Saravanapandian
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
| | - Charlotte DiStefano
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
| | - Scott Huberty
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
- McGill University, MUHC Research Institute, 5252, boul. de Maisonneuve Ouest, 3E.19, Montreal, QC H4A 3S5 Canada
| | - Carly Hyde
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
| | - Stormy Chamberlain
- Genetics and Genome Sciences, UConn Health, 400 Farmington Avenue, Farmington, CT 06030-6403 USA
| | - Carrie E. Bearden
- Department of Psychiatry and Biobehavioral Sciences and Department of Psychology, University of California Los Angeles, Suite A7-460, 760 Westwood Plaza, Los Angeles, CA 90095 USA
| | - Peyman Golshani
- Department of Neurology and Psychiatry, David Geffen School of Medicine, 710 Westwood Plaza, Los Angeles, CA 90095 USA
| | - Andrei Irimia
- Leonard Davis School of Gerontology, University of Southern California, 3715 McClintock Ave., Suite 228C, California, Los Angeles 90089 USA
| | - Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, California, Los Angeles 90095 USA
| | - Joerg F. Hipp
- Roche Pharma Research and Early Development, Neuroscience, Ophthalmology and Rare Diseases, Roche Innovation Center Basel, Basel, Switzerland
| | - Shafali S. Jeste
- Center for Autism Research and Treatment, University of California Los Angeles, Semel Institute for Neuroscience, Los Angeles, CA 90024 USA
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Andersson JD, Matuskey D, Finnema SJ. Positron emission tomography imaging of the γ-aminobutyric acid system. Neurosci Lett 2018; 691:35-43. [PMID: 30102960 DOI: 10.1016/j.neulet.2018.08.010] [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: 05/01/2018] [Revised: 08/06/2018] [Accepted: 08/09/2018] [Indexed: 01/08/2023]
Abstract
In this review, we summarize the recent development of positron emission tomography (PET) radioligands for γ-aminobutyric acid A (GABAA) receptors and their potential to measure changes in endogenous GABA levels and highlight the clinical and translational applications of GABA-sensitive PET radioligands. We review the basic physiology of the GABA system with a focus on the importance of GABAA receptors in the brain and specifically the benzodiazepine binding site. Challenges for the development of central nervous system radioligands and particularly for radioligands with increased GABA sensitivity are outlined, as well as the status of established benzodiazepine site PET radioligands and agonist GABAA radioligands. We underline the challenge of using allosteric interactions to measure GABA concentrations and review the current state of PET imaging of changes in GABA levels. We conclude that PET tracers with increased GABA sensitivity are required to efficiently measure GABA release and that such a tool could be broadly applied to assess GABA transmission in vivo across several disorders.
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Affiliation(s)
- Jan D Andersson
- University of Alberta, Medical Isotope and Cyclotron Facility, Edmonton, Canada
| | - David Matuskey
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Sjoerd J Finnema
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA; Center for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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20
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Schifani C, Hafizi S, Da Silva T, Watts JJ, Khan MS, Mizrahi R. Using molecular imaging to understand early schizophrenia-related psychosis neurochemistry: a review of human studies. Int Rev Psychiatry 2017; 29:555-566. [PMID: 29219634 PMCID: PMC8011813 DOI: 10.1080/09540261.2017.1396205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Schizophrenia is a chronic psychiatric disorder generally preceded by a so-called prodromal phase, which is characterized by attenuated psychotic symptoms. Advances in clinical research have enabled prospective identification of those individuals who are at clinical high risk (CHR) for psychosis, with the power to predict psychosis onset within the near future. Changes in several brain neurochemical systems and molecular mechanisms are implicated in the pathophysiology of schizophrenia and the psychosis spectrum, including the dopaminergic, γ-aminobutyric acid (GABA)-ergic, glutamatergic, endocannabinoid, and immunologic (i.e. glial activation) system and other promising future directions such as synaptic density, which are possible to quantify in vivo using positron emission tomography (PET). This paper aims to review in vivo PET studies in the mentioned systems in the early course of psychosis (i.e. CHR and first-episode psychosis (FEP)). The results of reviewed studies are promising; however, the current understanding of the underlying pathology of psychosis is still limited. Importantly, promising efforts involve the development of novel PET radiotracers targeting systems with growing interest in schizophrenia, like the nociceptive system and synaptic density.
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Affiliation(s)
- Christin Schifani
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Jeremy Joseph Watts
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - M. Saad Khan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
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21
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Mick I, Ramos AC, Myers J, Stokes PR, Chandrasekera S, Erritzoe D, Mendez MA, Gunn RN, Rabiner EA, Searle GE, Galduróz JCF, Waldman AD, Bowden-Jones H, Clark L, Nutt DJ, Lingford-Hughes AR. Evidence for GABA-A receptor dysregulation in gambling disorder: correlation with impulsivity. Addict Biol 2017; 22:1601-1609. [PMID: 27739164 PMCID: PMC5697606 DOI: 10.1111/adb.12457] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/14/2016] [Accepted: 08/30/2016] [Indexed: 12/11/2022]
Abstract
As a behavioural addiction, gambling disorder (GD) provides an opportunity to characterize addictive processes without the potentially confounding effects of chronic excessive drug and alcohol exposure. Impulsivity is an established precursor to such addictive behaviours, and GD is associated with greater impulsivity. There is also evidence of GABAergic dysregulation in substance addiction and in impulsivity. This study therefore investigated GABAA receptor availability in 15 individuals with GD and 19 healthy volunteers (HV) using [11C]Ro15‐4513, a relatively selective α5 benzodiazepine receptor PET tracer and its relationship with impulsivity. We found significantly higher [11C]Ro15‐4513 total distribution volume (VT) in the right hippocampus in the GD group compared with HV. We found higher levels of the ‘Negative Urgency’ construct of impulsivity in GD, and these were positively associated with higher [11C]Ro15‐4513 VT in the amygdala in the GD group; no such significant correlations were evident in the HV group. These results contrast with reduced binding of GABAergic PET ligands described previously in alcohol and opiate addiction and add to growing evidence for distinctions in the neuropharmacology between substance and behavioural addictions. These results provide the first characterization of GABAA receptors in GD with [11C]Ro15‐4513 PET and show greater α5 receptor availability and positive correlations with trait impulsivity. This GABAergic dysregulation is potential target for treatment.
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Affiliation(s)
- Inge Mick
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
| | - Anna C. Ramos
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
- Department of Psychobiology; Universidade Federal de São Paulo; Brazil
| | - Jim Myers
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
| | - Paul R. Stokes
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
- Centre for Affective Disorders, Department of Psychological Medicine; Institute of Psychiatry, Psychology and Neuroscience, King's College London; UK
| | - Samantha Chandrasekera
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
| | - David Erritzoe
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
| | - Maria A. Mendez
- Forensic and Neurodevelopmental Sciences; Institute of Psychiatry, King's College; UK
| | - Roger N. Gunn
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
- Imanova Ltd.; Centre for Imaging Sciences; UK
| | - Eugenii A. Rabiner
- Imanova Ltd.; Centre for Imaging Sciences; UK
- Department of Neuroimaging; Institute of Psychiatry, King's College; UK
| | | | | | - Adam D. Waldman
- Department of Imaging, Division of Experimental Medicine, Department of Medicine; Imperial College; UK
| | - Henrietta Bowden-Jones
- National Problem Gambling Clinic, CNWL NHS Foundation Trust; Imperial College London; UK
| | - Luke Clark
- Centre for Gambling Research at UBC, Department of Psychology; University of British Columbia; Canada
| | - David J. Nutt
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
| | - Anne R. Lingford-Hughes
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Faculty of Medicine; Imperial College London; UK
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McGinnity CJ, Riaño Barros DA, Rosso L, Veronese M, Rizzo G, Bertoldo A, Hinz R, Turkheimer FE, Koepp MJ, Hammers A. Test-retest reproducibility of quantitative binding measures of [ 11C]Ro15-4513, a PET ligand for GABA A receptors containing alpha5 subunits. Neuroimage 2017; 152:270-282. [PMID: 28292717 PMCID: PMC5440177 DOI: 10.1016/j.neuroimage.2016.12.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/20/2016] [Accepted: 12/14/2016] [Indexed: 12/22/2022] Open
Abstract
INTRODUCTION Alteration of γ-aminobutyric acid "A" (GABAA) receptor-mediated neurotransmission has been associated with various neurological and psychiatric disorders. [11C]Ro15-4513 is a PET ligand with high affinity for α5-subunit-containing GABAA receptors, which are highly expressed in limbic regions of the human brain (Sur et al., 1998). We quantified the test-retest reproducibility of measures of [11C]Ro15-4513 binding derived from six different quantification methods (12 variants). METHODS Five healthy males (median age 40 years, range 38-49 years) had a 90-min PET scan on two occasions (median interval 12 days, range 11-30 days), after injection of a median dose of 441 MegaBequerels of [11C]Ro15-4513. Metabolite-corrected arterial plasma input functions (parent plasma input functions, ppIFs) were generated for all scans. We quantified regional binding using six methods (12 variants), some of which were region-based (applied to the average time-activity curve within a region) and others were voxel-based: 1) Models requiring arterial ppIFs - regional reversible compartmental models with one and two tissue compartments (2kbv and 4kbv); 2) Regional and voxelwise Logan's graphical analyses (Logan et al., 1990), which required arterial ppIFs; 3) Model-free regional and voxelwise (exponential) spectral analyses (SA; (Cunningham and Jones, 1993)), which also required arterial ppIFs; 4) methods not requiring arterial ppIFs - voxelwise standardised uptake values (Kenney et al., 1941), and regional and voxelwise simplified reference tissue models (SRTM/SRTM2) using brainstem or alternatively cerebellum as pseudo-reference regions (Lammertsma and Hume, 1996; Gunn et al., 1997). To compare the variants, we sampled the mean values of the outcome parameters within six bilateral, non-reference grey matter regions-of-interest. Reliability was quantified in terms of median absolute percentage test-retest differences (MA-TDs; preferentially low) and between-subject coefficient of variation (BS-CV, preferentially high), both compounded by the intraclass correlation coefficient (ICC). These measures were compared between variants, with particular interest in the hippocampus. RESULTS Two of the six methods (5/12 variants) yielded reproducible data (i.e. MA-TD <10%): regional SRTMs and voxelwise SRTM2s, both using either the brainstem or the cerebellum; and voxelwise SA. However, the SRTMs using the brainstem yielded a lower median BS-CV (7% for regional, 7% voxelwise) than the other variants (8-11%), resulting in lower ICCs. The median ICCs across six regions were 0.89 (interquartile range 0.75-0.90) for voxelwise SA, 0.71 (0.64-0.84) for regional SRTM-cerebellum and 0.83 (0.70-0.86) for voxelwise SRTM-cerebellum. The ICCs for the hippocampus were 0.89 for voxelwise SA, 0.95 for regional SRTM-cerebellum and 0.93 for voxelwise SRTM-cerebellum. CONCLUSION Quantification of [11C]Ro15-4513 binding shows very good to excellent reproducibility with SRTM and with voxelwise SA which, however, requires an arterial ppIF. Quantification in the α5 subunit-rich hippocampus is particularly reliable. The very low expression of the α5 in the cerebellum (Fritschy and Mohler, 1995; Veronese et al., 2016) and the substantial α1 subunit density in this region may hamper the application of reference tissue methods.
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Affiliation(s)
- Colm J McGinnity
- Centre for Neuroscience, Department of Medicine, Imperial College London, London, UK; Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London, UK; Division of Imaging Sciences & Biomedical Engineering, King's College London, London, UK.
| | - Daniela A Riaño Barros
- Centre for Neuroscience, Department of Medicine, Imperial College London, London, UK; Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London, UK
| | - Lula Rosso
- Centre for Neuroscience, Department of Medicine, Imperial College London, London, UK; Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London, UK
| | - Mattia Veronese
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Gaia Rizzo
- Department of Information Engineering, University of Padova, Padova, Italy
| | | | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK
| | - Federico E Turkheimer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Matthias J Koepp
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, UK; Epilepsy Society, Chalfont St Peter, UK
| | - Alexander Hammers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London, UK; Medical Research Council Clinical Sciences Centre, Hammersmith Hospital, London, UK; Division of Imaging Sciences & Biomedical Engineering, King's College London, London, UK; The Neurodis Foundation, CERMEP - Imagerie du Vivant, Lyon, France
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