1
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Auvity S, Vodovar D, Goutal S, Cisternino S, Chevillard L, Soyer A, Bottlaender M, Caillé F, Mégarbane B, Tournier N. Brain PET imaging using 11C-flumazenil and 11C-buprenorphine does not support the hypothesis of a mutual interaction between buprenorphine and benzodiazepines at the neuroreceptor level. J Cereb Blood Flow Metab 2024; 44:449-458. [PMID: 38097513 PMCID: PMC10870960 DOI: 10.1177/0271678x231221040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/20/2023] [Accepted: 11/20/2023] [Indexed: 02/16/2024]
Abstract
Among opioids, buprenorphine presents a favorable safety profile with a limited risk of respiratory depression. However, fatalities have been reported when buprenorphine is combined to a benzodiazepine. Potentiation of buprenorphine interaction with opioid receptors (ORs) with benzodiazepines, and/or vice versa, is hypothesized to explain this drug-drug interaction (DDI). The mutual DDI between buprenorphine and benzodiazepines was investigated at the neuroreceptor level in nonhuman primates (n = 4 individuals) using brain PET imaging and kinetic modelling. The binding potential (BPND) of benzodiazepine receptor (BzR) was assessed using 11C-flumazenil PET imaging before and after administration of buprenorphine (0.2 mg, i.v.). Moreover, the brain kinetics and receptor binding of buprenorphine were investigated in the same individuals using 11C-buprenorphine PET imaging before and after administration of diazepam (10 mg, i.v.). Outcome parameters were compared using a two-way ANOVA. Buprenorphine did not impact the plasma nor brain kinetics of 11C-flumazenil. 11C-flumazenil BPND was unchanged following buprenorphine exposure, in any brain region (p > 0.05). Similarly, diazepam did not impact the plasma or brain kinetics of 11C-buprenorphine. 11C-buprenorphine volume of distribution (VT) was unchanged following diazepam exposure, in any brain region (p > 0.05). To conclude, our PET imaging findings do not support a neuropharmacokinetic or neuroreceptor-related mechanism of the buprenorphine/benzodiazepine interaction.
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Affiliation(s)
- Sylvain Auvity
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Dominique Vodovar
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
- Réanimation Médicale et Toxicologique, Hôpital Lariboisière, Fédération de Toxicologie (APHP), 75010, Paris
| | - Sébastien Goutal
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Salvatore Cisternino
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Lucie Chevillard
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
| | - Amélie Soyer
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Michel Bottlaender
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Fabien Caillé
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
| | - Bruno Mégarbane
- Faculté de Pharmacie, Université Paris Cité, Inserm, UMRS-1144, Optimisation Thérapeutique en Neuropsychopharmacologie, 75006 Paris, France
- Réanimation Médicale et Toxicologique, Hôpital Lariboisière, Fédération de Toxicologie (APHP), 75010, Paris
| | - Nicolas Tournier
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), Orsay, France
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2
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Kong Y, Li QB, Yuan ZH, Jiang XF, Zhang GQ, Cheng N, Dang N. Multimodal Neuroimaging in Rett Syndrome With MECP2 Mutation. Front Neurol 2022; 13:838206. [PMID: 35280272 PMCID: PMC8904872 DOI: 10.3389/fneur.2022.838206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/24/2022] [Indexed: 01/11/2023] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder characterized by severe cognitive, social, and physical impairments resulting from de novo mutations in the X-chromosomal methyl-CpG binding protein gene 2 (MECP2). While there is still no cure for RTT, exploring up-to date neurofunctional diagnostic markers, discovering new potential therapeutic targets, and searching for novel drug efficacy evaluation indicators are fundamental. Multiple neuroimaging studies on brain structure and function have been carried out in RTT-linked gene mutation carriers to unravel disease-specific imaging features and explore genotype-phenotype associations. Here, we reviewed the neuroimaging literature on this disorder. MRI morphologic studies have shown global atrophy of gray matter (GM) and white matter (WM) and regional variations in brain maturation. Diffusion tensor imaging (DTI) studies have demonstrated reduced fractional anisotropy (FA) in left peripheral WM areas, left major WM tracts, and cingulum bilaterally, and WM microstructural/network topology changes have been further found to be correlated with behavioral abnormalities in RTT. Cerebral blood perfusion imaging studies using single-photon emission CT (SPECT) or PET have evidenced a decreased global cerebral blood flow (CBF), particularly in prefrontal and temporoparietal areas, while magnetic resonance spectroscopy (MRS) and PET studies have contributed to unraveling metabolic alterations in patients with RTT. The results obtained from the available reports confirm that multimodal neuroimaging can provide new insights into a complex interplay between genes, neurotransmitter pathway abnormalities, disease-related behaviors, and clinical severity. However, common limitations related to the available studies include small sample sizes and hypothesis-based and region-specific approaches. We, therefore, conclude that this field is still in its early development phase and that multimodal/multisequence studies with improved post-processing technologies as well as combined PET–MRI approaches are urgently needed to further explore RTT brain alterations.
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Affiliation(s)
- Yu Kong
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
- *Correspondence: Yu Kong
| | - Qiu-bo Li
- Department of Pediatrics, Affiliated Hospital of Jining Medical University, Jining, China
| | - Zhao-hong Yuan
- Department of Pediatric Rehabilitation, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xiu-fang Jiang
- Department of Pediatric Rehabilitation, Affiliated Hospital of Jining Medical University, Jining, China
| | - Gu-qing Zhang
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
- Gu-qing Zhang
| | - Nan Cheng
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
| | - Na Dang
- Department of Medical Imaging, Affiliated Hospital of Jining Medical University, Jining, China
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3
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Shaw AD, Chandler HL, Hamandi K, Muthukumaraswamy SD, Hammers A, Singh KD. Tiagabine induced modulation of oscillatory connectivity and activity match PET-derived, canonical GABA-A receptor distributions. Eur Neuropsychopharmacol 2021; 50:34-45. [PMID: 33957336 PMCID: PMC8415204 DOI: 10.1016/j.euroneuro.2021.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 03/30/2021] [Accepted: 04/11/2021] [Indexed: 12/04/2022]
Abstract
As the most abundant inhibitory neurotransmitter in the mammalian brain, γ-aminobutyric acid (GABA) plays a crucial role in shaping the frequency and amplitude of oscillations, which suggests a role for GABA in shaping the topography of functional connectivity and activity. This study explored the effects of pharmacologically blocking the reuptake of GABA (increasing local concentrations) using the GABA transporter 1 (GAT1) blocker, tiagabine (15 mg). In a placebo-controlled crossover design, we collected resting magnetoencephalography (MEG) recordings from 15 healthy individuals prior to, and at 1-, 3- and 5- hours post, administration of tiagabine and placebo. We quantified whole brain activity and functional connectivity in discrete frequency bands. Drug-by-session (2 × 4) analysis of variance in connectivity revealed interaction and main effects. Post-hoc permutation testing of each post-drug recording vs. respective pre-drug baseline revealed consistent reductions of a bilateral occipital network spanning theta, alpha and beta frequencies, across 1- 3- and 5- hour recordings following tiagabine only. The same analysis applied to activity revealed significant increases across frontal regions, coupled with reductions in posterior regions, across delta, theta, alpha and beta frequencies. Crucially, the spatial distribution of tiagabine-induced changes overlap with group-averaged maps of the distribution of GABAA receptors, from flumazenil (FMZ-VT) PET, demonstrating a link between GABA availability, GABAA receptor distribution, and low-frequency network oscillations. Our results indicate that the relationship between PET receptor distributions and MEG effects warrants further exploration, since elucidating the nature of this relationship may uncover electrophysiologically-derived maps of oscillatory activity as sensitive, time-resolved, and targeted receptor-mapping tools for pharmacological imaging.
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Affiliation(s)
- Alexander D Shaw
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, CF24 4HQ, Wales.
| | - Hannah L Chandler
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, CF24 4HQ, Wales
| | - Khalid Hamandi
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, CF24 4HQ, Wales
| | - Suresh D Muthukumaraswamy
- School of Pharmacy, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Alexander Hammers
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, London SE1 7EH, United States
| | - Krish D Singh
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, CF24 4HQ, Wales
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4
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Kang Y, Rúa SMH, Kaunzner UW, Perumal J, Nealon N, Qu W, Kothari PJ, Vartanian T, Kuceyeski A, Gauthier SA. A Multi-Ligand Imaging Study Exploring GABAergic Receptor Expression and Inflammation in Multiple Sclerosis. Mol Imaging Biol 2021; 22:1600-1608. [PMID: 32394283 DOI: 10.1007/s11307-020-01501-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE The γ-aminobutyric acid (GABA) is the main inhibitory neurotransmitter and essential for normal brain function. The GABAergic system has been shown to have immunomodulatory effects and respond adaptively to excitatory toxicity. The association of the GABAergic system and inflammation in patients with multiple sclerosis (MS) remains unknown. In this pilot study, the in vivo relationship between GABAA binding and the innate immune response is explored using positron emission tomography (PET) with [11C] flumazenil (FMZ) and [11C]-PK11195 PET (PK-PET), a measure of activated microglia/macrophages. PROCEDURES Sixteen MS patients had dynamic FMZ-PET and PK-PET imaging. Ten age-matched healthy controls (HC) had a single FMZ-PET. GABAA receptor binding was calculated using Logan reference model with the pons as reference. Distribution of volume ratio (VTr) for PK-PET was calculated using image-derived input function. A hierarchical linear model was fitted to assess the linear association between PK-PET and FMZ-PET among six cortical regions of interest. RESULTS GABAA receptor binding was higher throughout the cortex in MS patients (5.72 ± 0.91) as compared with HC (4.70 ± 0.41) (p = 0.002). A significant correlation was found between FMZ binding and PK-PET within the cortex (r = 0.61, p < 0.001) and among the occipital (r = 0.61, p = 0.012), parietal (r = 0.49, p = 0.041), and cingulate (r = 0.32, p = 0.006) regions. CONCLUSIONS A higher GABAA receptor density in MS subjects compared with HC was observed and correlated with innate immune activity. Our observations demonstrate that immune-driven GABAergic abnormalities may be present in MS.
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Affiliation(s)
- Yeona Kang
- Department of Radiology, Weill Cornell Medicine, New York, NY, 10021, USA.,Department of Mathematics, Howard University, Washington, D.C, 20059, USA
| | - Sandra Milena Hurtado Rúa
- Department of Mathematics and Statistics, College of Science and Health Professions, Cleveland State University, Cleveland, OH, 44115, USA
| | - Ulrike W Kaunzner
- Department of Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Jai Perumal
- Department of Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Nancy Nealon
- Department of Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Wenchao Qu
- Department of Radiology, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Paresh J Kothari
- Department of Radiology, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Timothy Vartanian
- Department of Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medicine, New York, NY, 10021, USA.,Feil Family Brain and Mind Institute, Weill Cornell, New York, NY, 10021, USA
| | - Amy Kuceyeski
- Department of Radiology, Weill Cornell Medicine, New York, NY, 10021, USA.,Feil Family Brain and Mind Institute, Weill Cornell, New York, NY, 10021, USA
| | - Susan A Gauthier
- Department of Radiology, Weill Cornell Medicine, New York, NY, 10021, USA. .,Department of Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medicine, New York, NY, 10021, USA. .,Feil Family Brain and Mind Institute, Weill Cornell, New York, NY, 10021, USA.
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5
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Novel PET Biomarkers to Disentangle Molecular Pathways across Age-Related Neurodegenerative Diseases. Cells 2020; 9:cells9122581. [PMID: 33276490 PMCID: PMC7761606 DOI: 10.3390/cells9122581] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/25/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022] Open
Abstract
There is a need to disentangle the etiological puzzle of age-related neurodegenerative diseases, whose clinical phenotypes arise from known, and as yet unknown, pathways that can act distinctly or in concert. Enhanced sub-phenotyping and the identification of in vivo biomarker-driven signature profiles could improve the stratification of patients into clinical trials and, potentially, help to drive the treatment landscape towards the precision medicine paradigm. The rapidly growing field of neuroimaging offers valuable tools to investigate disease pathophysiology and molecular pathways in humans, with the potential to capture the whole disease course starting from preclinical stages. Positron emission tomography (PET) combines the advantages of a versatile imaging technique with the ability to quantify, to nanomolar sensitivity, molecular targets in vivo. This review will discuss current research and available imaging biomarkers evaluating dysregulation of the main molecular pathways across age-related neurodegenerative diseases. The molecular pathways focused on in this review involve mitochondrial dysfunction and energy dysregulation; neuroinflammation; protein misfolding; aggregation and the concepts of pathobiology, synaptic dysfunction, neurotransmitter dysregulation and dysfunction of the glymphatic system. The use of PET imaging to dissect these molecular pathways and the potential to aid sub-phenotyping will be discussed, with a focus on novel PET biomarkers.
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6
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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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7
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Abstract
Neuroimaging with positron emission tomography (PET) is the most powerful tool for understanding pharmacology, neurochemistry, and pathology in the living human brain. This technology combines high-resolution scanners to measure radioactivity throughout the human body with specific, targeted radioactive molecules, which allow measurements of a myriad of biological processes in vivo. While PET brain imaging has been active for almost 40 years, the pace of development for neuroimaging tools, known as radiotracers, and for quantitative analytical techniques has increased dramatically over the past decade. Accordingly, the fundamental questions that can be addressed with PET have expanded in basic neurobiology, psychiatry, neurology, and related therapeutic development. In this review, we introduce the field of human PET neuroimaging, some of its conceptual underpinnings, and motivating questions. We highlight some of the more recent advances in radiotracer development, quantitative modeling, and applications of PET to the study of the human brain.
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Affiliation(s)
- Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129, USA;
| | - Richard E Carson
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, USA;
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8
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Honda S, Matsumoto M, Tajinda K, Mihara T. Enhancing Clinical Trials Through Synergistic Gamma Power Analysis. Front Psychiatry 2020; 11:537. [PMID: 32587536 PMCID: PMC7299152 DOI: 10.3389/fpsyt.2020.00537] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022] Open
Abstract
While the etiology of many neuropsychiatric disorders remains unknown, increasing evidence suggests that aberrant sensory processing plays a central role. For this class of disorders, which are characterized by affective, cognitive, and behavioral symptoms, electroencephalography remains the dominant tool for providing insight into the physiological and molecular underpinnings of the disease state and predicting the effectiveness of investigational new drugs. Within the spectrum of electrical activity present in the CNS, high-frequency oscillations in the gamma band are frequently altered in these patient populations. Measurement of gamma oscillation can be further classified into baseline and evoked, each of which offers a specific commentary on disease state. Baseline gamma analysis provides a surrogate of pharmacodynamics and predicting the time course effects of clinical candidate drugs, while alterations in evoked (time-locked) gamma power may serve as a disease biomarker and have utility in assessing patient response to new drugs. Together, these techniques offer complimentary methods of analysis for discrete realms of clinical and translational medicine. In terms of drug development, comprehensive analysis containing aspects of both baseline and evoked gamma oscillations may prove more useful in establishing better workflow and more accurate criteria for the testing of investigational new drugs.
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Affiliation(s)
- Sokichi Honda
- Neuroscience, La Jolla Laboratory, Astellas Research Institute of America LLC, San Diego, CA, United States
| | - Mitsuyuki Matsumoto
- Neuroscience, La Jolla Laboratory, Astellas Research Institute of America LLC, San Diego, CA, United States
| | - Katsunori Tajinda
- Neuroscience, La Jolla Laboratory, Astellas Research Institute of America LLC, San Diego, CA, United States
| | - Takuma Mihara
- Candidate Discovery Research Labs, DDR, Astellas Pharm Inc., Tsukuba, Japan
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9
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Beaurain M, Salabert AS, Ribeiro MJ, Arlicot N, Damier P, Le Jeune F, Demonet JF, Payoux P. Innovative Molecular Imaging for Clinical Research, Therapeutic Stratification, and Nosography in Neuroscience. Front Med (Lausanne) 2019; 6:268. [PMID: 31828073 PMCID: PMC6890558 DOI: 10.3389/fmed.2019.00268] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 11/01/2019] [Indexed: 01/06/2023] Open
Abstract
Over the past few decades, several radiotracers have been developed for neuroimaging applications, especially in PET. Because of their low steric hindrance, PET radionuclides can be used to label molecules that are small enough to cross the blood brain barrier, without modifying their biological properties. As the use of 11C is limited by its short physical half-life (20 min), there has been an increasing focus on developing tracers labeled with 18F for clinical use. The first such tracers allowed cerebral blood flow and glucose metabolism to be measured, and the development of molecular imaging has since enabled to focus more closely on specific targets such as receptors, neurotransmitter transporters, and other proteins. Hence, PET and SPECT biomarkers have become indispensable for innovative clinical research. Currently, the treatment options for a number of pathologies, notably neurodegenerative diseases, remain only supportive and symptomatic. Treatments that slow down or reverse disease progression are therefore the subject of numerous studies, in which molecular imaging is proving to be a powerful tool. PET and SPECT biomarkers already make it possible to diagnose several neurological diseases in vivo and at preclinical stages, yielding topographic, and quantitative data about the target. As a result, they can be used for assessing patients' eligibility for new treatments, or for treatment follow-up. The aim of the present review was to map major innovative radiotracers used in neuroscience, and explain their contribution to clinical research. We categorized them according to their target: dopaminergic, cholinergic or serotoninergic systems, β-amyloid plaques, tau protein, neuroinflammation, glutamate or GABA receptors, or α-synuclein. Most neurological disorders, and indeed mental disorders, involve the dysfunction of one or more of these targets. Combinations of molecular imaging biomarkers can afford us a better understanding of the mechanisms underlying disease development over time, and contribute to early detection/screening, diagnosis, therapy delivery/monitoring, and treatment follow-up in both research and clinical settings.
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Affiliation(s)
- Marie Beaurain
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Anne-Sophie Salabert
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Maria Joao Ribeiro
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Nicolas Arlicot
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Philippe Damier
- Inserm U913, Neurology Department, University Hospital, Nantes, France
| | | | - Jean-François Demonet
- Leenards Memory Centre, Department of Clinical Neuroscience, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Pierre Payoux
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
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10
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Dienel SJ, Lewis DA. Alterations in cortical interneurons and cognitive function in schizophrenia. Neurobiol Dis 2019; 131:104208. [PMID: 29936230 PMCID: PMC6309598 DOI: 10.1016/j.nbd.2018.06.020] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 05/31/2018] [Accepted: 06/20/2018] [Indexed: 12/18/2022] Open
Abstract
Certain clinical features of schizophrenia, such as working memory disturbances, appear to emerge from altered gamma oscillatory activity in the prefrontal cortex (PFC). Given the essential role of GABA neurotransmission in both working memory and gamma oscillations, understanding the cellular substrate for their disturbances in schizophrenia requires evidence from in vivo neuroimaging studies, which provide a means to link markers of GABA neurotransmission to gamma oscillations and working memory, and from postmortem studies, which provide insight into GABA neurotransmission at molecular and cellular levels of resolution. Here, we review findings from both types of studies which converge on the notions that 1) inhibitory GABA signaling in the PFC, especially between parvalbumin positive GABAergic basket cells and excitatory pyramidal cells, is required for gamma oscillatory activity and working memory function; and 2) disturbances in this signaling contribute to altered gamma oscillations and working memory in schizophrenia. Because the PFC is only one node in a distributed cortical network that mediates working memory, we also review evidence of GABA abnormalities in other cortical regions in schizophrenia.
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Affiliation(s)
- Samuel J Dienel
- Medical Scientist Training Program, University of Pittsburgh, United States; Translational Neuroscience Program, Department of Psychiatry, School of Medicine, University of Pittsburgh, United States
| | - David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, School of Medicine, University of Pittsburgh, United States; Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, United States.
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11
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Piras F, Piras F, Banaj N, Ciullo V, Vecchio D, Edden RAE, Spalletta G. Cerebellar GABAergic correlates of cognition-mediated verbal fluency in physiology and schizophrenia. Acta Psychiatr Scand 2019; 139:582-594. [PMID: 30887499 DOI: 10.1111/acps.13027] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/11/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Defective cerebellar GABAergic inhibitory control may participate to the cognitive impairments seen in SZ. We tested the prediction of a model for the relationship between cerebellar GABA concentration and the associative/executive processes required by verbal fluency in patients with schizophrenia (SZ) and matched healthy controls (HC). METHOD Magnetic resonance spectroscopy of GABA was performed using a 3 Tesla scanner and verbal fluency assessed by the Controlled Word (WFT) and Semantic (SFT) Fluency tests. Cerebellar GABA measurements were obtained using the MEGA-PRESS acquisition sequence. Linear correlations between cerebellar GABA levels and the WFT, SFT score were performed to test differences between correlation coefficients of SZ and HC. Quantile regressions between GABA levels and the WFT score were performed. RESULTS Higher cerebellar GABA concentration was associated in SZ with lower phonemic fluency and reduced number of switches among subcategories as opposed to what observed in HC (with higher cerebellar GABA associated with higher number of words and phonemic switches). GABA levels explained phonemic fluency in SZ performing above the group mean. CONCLUSION Studying cerebellar GABA provides a valid heuristic to explore the molecular mechanisms of SZ. This is crucial for developing pharmacological treatments to improve cognition and functional recovery in SZ.
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Affiliation(s)
- F Piras
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy
| | - F Piras
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy
| | - N Banaj
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy
| | - V Ciullo
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy
| | - D Vecchio
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy
| | - R A E Edden
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, MD, USA.,F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - G Spalletta
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy.,Beth K. and Stuart C. Yudofsky Division of Neuropsychiatry, Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
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12
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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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13
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Murley AG, Rowe JB. Neurotransmitter deficits from frontotemporal lobar degeneration. Brain 2018; 141:1263-1285. [PMID: 29373632 PMCID: PMC5917782 DOI: 10.1093/brain/awx327] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 09/05/2017] [Accepted: 10/03/2017] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal lobar degeneration causes a spectrum of complex degenerative disorders including frontotemporal dementia, progressive supranuclear palsy and corticobasal syndrome, each of which is associated with changes in the principal neurotransmitter systems. We review the evidence for these neurochemical changes and propose that they contribute to symptomatology of frontotemporal lobar degeneration, over and above neuronal loss and atrophy. Despite the development of disease-modifying therapies, aiming to slow neuropathological progression, it remains important to advance symptomatic treatments to reduce the disease burden and improve patients' and carers' quality of life. We propose that targeting the selective deficiencies in neurotransmitter systems, including dopamine, noradrenaline, serotonin, acetylcholine, glutamate and gamma-aminobutyric acid is an important strategy towards this goal. We summarize the current evidence-base for pharmacological treatments and suggest strategies to improve the development of new, effective pharmacological treatments.
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Affiliation(s)
- Alexander G Murley
- Department of Clinical Neurosciences, University of Cambridge, Herchel Smith Building, Robinson Way, Cambridge, CB2 0SZ, UK
| | - James B Rowe
- Department of Clinical Neurosciences, University of Cambridge, Herchel Smith Building, Robinson Way, Cambridge, CB2 0SZ, UK
- MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, UK
- Behavioural and Clinical Neurosciences Institute, University of Cambridge, Sir William Hardy Building, Downing Street, Cambridge, CB2 3EB, UK
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14
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Bertelsen F, Landau AM, Vase KH, Jacobsen J, Scheel-Krüger J, Møller A. Acute in vivo effect of valproic acid on the GABAergic system in rat brain: A [ 11C]Ro15-4513 microPET study. Brain Res 2017; 1680:110-114. [PMID: 29258847 DOI: 10.1016/j.brainres.2017.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 12/08/2017] [Accepted: 12/13/2017] [Indexed: 02/05/2023]
Abstract
γ-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the nervous system acting mainly through GABAA receptors. In the presence of high levels of GABA, an allosteric shift in the GABAA receptors can change the affinity of benzodiazepine (BZD) ligands. Valproic acid (VPA) is an anticonvulsant that enhances the level of endogenous GABA in the brain. The BZD ligand, Ro15-4513 has a high affinity for GABAA receptors containing the α5 subunit and can be used to investigate the GABA shift in the brains of living rats after VPA exposure. Seven Wistar rats were scanned using a Mediso NanoScan PET/MRI. A baseline 90-min dynamic [11C]Ro15-4513 PET scan was acquired prior to an intravenous injection of 50 mg/kg VPA, and was followed by a second [11C]Ro15-4513 PET scan. Standardized uptake values were obtained for regions of high GABA binding, including the hippocampus and amygdala, and low GABA binding such as the cerebellum. We showed a significant increase in [11C]Ro15-4513 uptake in hippocampus and amygdala, but no significant differences in cerebellar uptake, after acute VPA exposure. In contrast to several in vitro studies, we demonstrated a positive allosteric change in the GABAA receptors after pharmacologically enhanced GABA levels resulting in enhanced Ro15-4513 uptake. Knowledge of how subtypes of the GABAA receptors react will provide us with information useful to fine-tune pharmacological interventions and design receptor subtype specific drugs.
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Affiliation(s)
- Freja Bertelsen
- Centre of Functionally Integrative Neuroscience, Aarhus University, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark; Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark.
| | - Anne M Landau
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark; Translational Neuropsychiatry Unit, Aarhus University, Skovagervej 2, Building 14J.1, 8240 Risskov, Denmark.
| | - Karina H Vase
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark.
| | - Jan Jacobsen
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark.
| | - Jørgen Scheel-Krüger
- Centre of Functionally Integrative Neuroscience, Aarhus University, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark.
| | - Arne Møller
- Centre of Functionally Integrative Neuroscience, Aarhus University, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark; Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Nørrebrogade 44, Building 10G, 8000 Aarhus, Denmark.
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15
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Heurling K, Leuzy A, Jonasson M, Frick A, Zimmer ER, Nordberg A, Lubberink M. Quantitative positron emission tomography in brain research. Brain Res 2017; 1670:220-234. [PMID: 28652218 DOI: 10.1016/j.brainres.2017.06.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 12/21/2022]
Abstract
The application of positron emission tomography (PET) in brain research has increased substantially during the past 20years, and is still growing. PET provides a unique insight into physiological and pathological processes in vivo. In this article we introduce the fundamentals of PET, and the methods available for acquiring quantitative estimates of the parameters of interest. A short introduction to different areas of application is also given, including basic research of brain function and in neurology, psychiatry, drug receptor occupancy studies, and its application in diagnostics of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Our aim is to inform the unfamiliar reader of the underlying basics and potential applications of PET, hoping to inspire the reader into considering how the technique could be of benefit for his or her own research.
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Affiliation(s)
- Kerstin Heurling
- Wallenberg Centre for Molecular and Translational Medicine and the Department of Psychiatry and Neurochemistry, University of Gothenburg, Sweden; Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
| | - Antoine Leuzy
- Department Neurobiology, Care Sciences and Society, Division of Translational Alzheimer Neurobiology, Karolinska Institutet, Stockholm, Sweden
| | - My Jonasson
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; Medical Physics, Uppsala University Hospital, Uppsala, Sweden
| | - Andreas Frick
- Department of Psychology, Uppsala University, Uppsala, Sweden; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Eduardo R Zimmer
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; Brain Institute of Rio Grande do Sul (BraIns), Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Agneta Nordberg
- Department Neurobiology, Care Sciences and Society, Division of Translational Alzheimer Neurobiology, Karolinska Institutet, Stockholm, Sweden; Department of Geriatric Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Mark Lubberink
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden; Medical Physics, Uppsala University Hospital, Uppsala, Sweden
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16
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Neuroimaging studies of GABA in schizophrenia: a systematic review with meta-analysis. Transl Psychiatry 2017; 7:e1147. [PMID: 28585933 PMCID: PMC5537645 DOI: 10.1038/tp.2017.124] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/26/2017] [Accepted: 05/03/2017] [Indexed: 01/17/2023] Open
Abstract
Data from animal models and from postmortem studies suggest that schizophrenia is associated with brain GABAergic dysfunction. The extent to which this is reflected in data from in vivo studies of GABA function in schizophrenia is unclear. The Medline database was searched to identify articles published until 21 October 2016. The search terms included GABA, proton magnetic resonance spectroscopy (1H-MRS), positron emission tomography (PET), single photon emission computed tomography (SPECT), schizophrenia and psychosis. Sixteen GABA 1H-MRS studies (538 controls, 526 patients) and seven PET/SPECT studies of GABAA/benzodiazepine receptor (GABAA/BZR) availability (118 controls, 113 patients) were identified. Meta-analyses of 1H-MRS GABA in the medial prefrontal cortex (mPFC), parietal/occipital cortex (POC) and striatum did not show significant group differences (mFC: g=-0.3, 409 patients, 495 controls, 95% confidence interval (CI): -0.6 to 0.1; POC: g=-0.3, 139 patients, 111 controls, 95% CI: -0.9 to 0.3; striatum: g=-0.004, 123 patients, 95 controls, 95% CI: -0.7 to 0.7). Heterogeneity across studies was high (I2>50%), and this was not explained by subsequent moderator or meta-regression analyses. There were insufficient PET/SPECT receptor availability studies for meta-analyses, but a systematic review did not suggest replicable group differences in regional GABAA/BZR availability. The current literature does not reveal consistent alterations in in vivo GABA neuroimaging measures in schizophrenia, as might be hypothesized from animal models and postmortem data. The analysis highlights the need for further GABA neuroimaging studies with improved methodology and addressing potential sources of heterogeneity.
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17
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PET measurement of "GABA shift" in the rat brain: A preclinical application of bolus plus constant infusion paradigm of [ 18F]flumazenil. Nucl Med Biol 2016; 45:30-34. [PMID: 27886620 DOI: 10.1016/j.nucmedbio.2016.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/22/2016] [Accepted: 11/01/2016] [Indexed: 11/21/2022]
Abstract
INTRODUCTION We measured the tiagabine-induced enhancement of the GABAA receptor's affinity for benzodiazepine ligands ("GABA shift") using [18F]flumazenil (FMZ) PET with preclinical application of bolus plus constant infusion (B/I). Differences in quantified results of [18F]FMZ binding were compared to that of [18F]FMZ PET with single bolus injection (SB). MATERIALS AND METHODS Sprague-Dawley rats underwent [18F]FMZ PET scans with B/I, which consisted of baseline and "GABA shift" sessions in a scan, or scans with SB one week apart. Tiagabine (10mg/kg) was intravenously injected after the baseline session. [18F]FMZ binding potentials (BPND) were calculated using an equilibrium ratio method and a modeling method for B/I and SB, respectively. Regional brain BPND changes (%) before and after the tiagabine treatment were also calculated. RESULTS In PET studies with B/I (Kbol=20min), [18F]FMZ distribution in the various cortical and subcortical regions rapidly reached equilibrium. After the tiagabine treatment, [18F]FMZ BPND were substantially increased across the regions of interest (the frontal cortex, hippocampus, thalamus, and striatum), ranging from 3% to 7% BPND change (B/I) and 6-14% BPND change (SB), respectively. In PET studies with SB, a statistically significant increase of [18F]FMZ BPND was found only in the striatum, due to the greater inter-individual variance compared to those with B/I. CONCLUSIONS Data demonstrated that an [18F]FMZ PET study with B/I (Kbol=20min) is both reliable and sensitive for the assessment of altered GABAA receptor function induced by tiagabine treatment in the rat brain. These results may help to improve the efficiency of the development of new GABA-targeting drugs in the preclinical stage using [18F]FMZ PET.
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18
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Abstract
The discovery and development of central nervous system (CNS) drugs is an extremely challenging process requiring large resources, timelines, and associated costs. The high risk of failure leads to high levels of risk. Over the past couple of decades PET imaging has become a central component of the CNS drug-development process, enabling decision-making in phase I studies, where early discharge of risk provides increased confidence to progress a candidate to more costly later phase testing at the right dose level or alternatively to kill a compound through failure to meet key criteria. The so called "3 pillars" of drug survival, namely; tissue exposure, target engagement, and pharmacologic activity, are particularly well suited for evaluation by PET imaging. This review introduces the process of CNS drug development before considering how PET imaging of the "3 pillars" has advanced to provide valuable tools for decision-making on the critical path of CNS drug development. Finally, we review the advances in PET science of biomarker development and analysis that enable sophisticated drug-development studies in man.
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Affiliation(s)
- Roger N Gunn
- Imanova Ltd, London, United Kingdom; Division of Brain Sciences, Imperial College London, London, United Kingdom; Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.
| | - Eugenii A Rabiner
- Imanova Ltd, London, United Kingdom; Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, London, United Kingdom
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19
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Slifstein M, Abi-Dargham A. Recent Developments in Molecular Brain Imaging of Neuropsychiatric Disorders. Semin Nucl Med 2016; 47:54-63. [PMID: 27987558 DOI: 10.1053/j.semnuclmed.2016.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Molecular imaging with PET or SPECT has been an important research tool in psychiatry for as long as these modalities have been available. Here, we discuss two areas of neuroimaging relevant to current psychiatry research. The first is the use of imaging to study neurotransmission. We discuss the use of pharmacologic probes to induce changes in levels of neurotransmitters that can be inferred through their effects on outcome measures of imaging experiments, from their historical origins focusing on dopamine transmission through recent developments involving serotonin, GABA, and glutamate. Next, we examine imaging of neuroinflammation in the context of psychiatry. Imaging markers of neuroinflammation have been studied extensively in other areas of brain research, but they have more recently attracted interest in psychiatry research, based on accumulating evidence that there may be an inflammatory component to some psychiatric conditions. Furthermore, new probes are under development that would allow unprecedented insights into cellular processes. In summary, molecular imaging would continue to offer great potential as a unique tool to further our understanding of brain function in health and disease.
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Affiliation(s)
- Mark Slifstein
- Department of Psychiatry, Columbia University Medical Center, New York, NY; New York State Psychiatric Institute, New York, NY; Department of Psychiatry, Stony Brook University, New York, NY.
| | - Anissa Abi-Dargham
- Department of Psychiatry, Columbia University Medical Center, New York, NY; Department of Radiology, Columbia University Medical Center, New York, NY; New York State Psychiatric Institute, New York, NY; Department of Psychiatry, Stony Brook University, New York, NY
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20
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Declercq LD, Vandenberghe R, Van Laere K, Verbruggen A, Bormans G. Drug Development in Alzheimer's Disease: The Contribution of PET and SPECT. Front Pharmacol 2016; 7:88. [PMID: 27065872 PMCID: PMC4814730 DOI: 10.3389/fphar.2016.00088] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 03/16/2016] [Indexed: 12/13/2022] Open
Abstract
Clinical trials aiming to develop disease-altering drugs for Alzheimer’s disease (AD), a neurodegenerative disorder with devastating consequences, are failing at an alarming rate. Poorly defined inclusion-and outcome criteria, due to a limited amount of objective biomarkers, is one of the major concerns. Non-invasive molecular imaging techniques, positron emission tomography and single photon emission (computed) tomography (PET and SPE(C)T), allow visualization and quantification of a wide variety of (patho)physiological processes and allow early (differential) diagnosis in many disorders. PET and SPECT have the ability to provide biomarkers that permit spatial assessment of pathophysiological molecular changes and therefore objectively evaluate and follow up therapeutic response, especially in the brain. A number of specific PET/SPECT biomarkers used in support of emerging clinical therapies in AD are discussed in this review.
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Affiliation(s)
- Lieven D Declercq
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven Leuven, Belgium
| | - Rik Vandenberghe
- Laboratory for Cognitive Neurology, Department of Neurosciences, KU Leuven Leuven, Belgium
| | - Koen Van Laere
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven Leuven, Belgium
| | - Alfons Verbruggen
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven Leuven, Belgium
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21
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Moeller SJ, London ED, Northoff G. Neuroimaging markers of glutamatergic and GABAergic systems in drug addiction: Relationships to resting-state functional connectivity. Neurosci Biobehav Rev 2016; 61:35-52. [PMID: 26657968 PMCID: PMC4731270 DOI: 10.1016/j.neubiorev.2015.11.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 11/05/2015] [Accepted: 11/21/2015] [Indexed: 12/29/2022]
Abstract
Drug addiction is characterized by widespread abnormalities in brain function and neurochemistry, including drug-associated effects on concentrations of the excitatory and inhibitory neurotransmitters glutamate and gamma-aminobutyric acid (GABA), respectively. In healthy individuals, these neurotransmitters drive the resting state, a default condition of brain function also disrupted in addiction. Here, our primary goal was to review in vivo magnetic resonance spectroscopy and positron emission tomography studies that examined markers of glutamate and GABA abnormalities in human drug addiction. Addicted individuals tended to show decreases in these markers compared with healthy controls, but findings also varied by individual characteristics (e.g., abstinence length). Interestingly, select corticolimbic brain regions showing glutamatergic and/or GABAergic abnormalities have been similarly implicated in resting-state functional connectivity deficits in drug addiction. Thus, our secondary goals were to provide a brief review of this resting-state literature, and an initial rationale for the hypothesis that abnormalities in glutamatergic and/or GABAergic neurotransmission may underlie resting-state functional deficits in drug addiction. In doing so, we suggest future research directions and possible treatment implications.
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Affiliation(s)
- Scott J Moeller
- Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Edythe D London
- Departments of Psychiatry and Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Departments of Psychiatry and Biobehavioral Sciences, and Molecular and Medical Pharmacology, University of California Los Angeles, Los Angeles, CA, USA
| | - Georg Northoff
- Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, Ottawa, Canada.
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22
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Lewis DA, Glausier JR. Alterations in Prefrontal Cortical Circuitry and Cognitive Dysfunction in Schizophrenia. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2016; 63:31-75. [PMID: 27627824 DOI: 10.1007/978-3-319-30596-7_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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23
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Kujala J, Jung J, Bouvard S, Lecaignard F, Lothe A, Bouet R, Ciumas C, Ryvlin P, Jerbi K. Gamma oscillations in V1 are correlated with GABA(A) receptor density: A multi-modal MEG and Flumazenil-PET study. Sci Rep 2015; 5:16347. [PMID: 26572733 PMCID: PMC4647220 DOI: 10.1038/srep16347] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/12/2015] [Indexed: 12/02/2022] Open
Abstract
High-frequency oscillations in the gamma-band reflect rhythmic synchronization of spike timing in active neural networks. The modulation of gamma oscillations is a widely established mechanism in a variety of neurobiological processes, yet its neurochemical basis is not fully understood. Modeling, in-vitro and in-vivo animal studies suggest that gamma oscillation properties depend on GABAergic inhibition. In humans, search for evidence linking total GABA concentration to gamma oscillations has led to promising -but also to partly diverging- observations. Here, we provide the first evidence of a direct relationship between the density of GABAA receptors and gamma oscillatory gamma responses in human primary visual cortex (V1). By combining Flumazenil-PET (to measure resting-levels of GABAA receptor density) and MEG (to measure visually-induced gamma oscillations), we found that GABAA receptor densities correlated positively with the frequency and negatively with amplitude of visually-induced gamma oscillations in V1. Our findings demonstrate that gamma-band response profiles of primary visual cortex across healthy individuals are shaped by GABAA-receptor-mediated inhibitory neurotransmission. These results bridge the gap with in-vitro and animal studies and may have future clinical implications given that altered GABAergic function, including dysregulation of GABAA receptors, has been related to psychiatric disorders including schizophrenia and depression.
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Affiliation(s)
- Jan Kujala
- Department of Neuroscience and Biomedical Engineering, Aalto University, 02150 Espoo, Finland.,Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France
| | - Julien Jung
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France.,Department of Epileptology and Functional Neurology, Lyon Neurological Hospital, F-69000, Lyon, France
| | - Sandrine Bouvard
- CERMEP imaging center, F-69003, Bron, France.,Institute for Child and Adolescent with Epilepsy (IDEE), F-69000, Lyon, France
| | - Françoise Lecaignard
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France.,CERMEP imaging center, F-69003, Bron, France
| | - Amélie Lothe
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France
| | - Romain Bouet
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France
| | - Carolina Ciumas
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France.,Institute for Child and Adolescent with Epilepsy (IDEE), F-69000, Lyon, France
| | - Philippe Ryvlin
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France.,Institute for Child and Adolescent with Epilepsy (IDEE), F-69000, Lyon, France.,Department of Clinical Neurosciences, CHUV, 1011, Lausanne, Switzerland
| | - Karim Jerbi
- Lyon Neuroscience Research Center, INSERM U1028-CNRS UMR5292, F-69000, Lyon, France.,Department of Psychology, University of Montreal, H3C 3J7 Montreal, Québec, Canada
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24
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Frankle WG, Cho RY, Prasad KM, Mason NS, Paris J, Himes ML, Walker C, Lewis DA, Narendran R. In vivo measurement of GABA transmission in healthy subjects and schizophrenia patients. Am J Psychiatry 2015; 172:1148-59. [PMID: 26133962 PMCID: PMC5070491 DOI: 10.1176/appi.ajp.2015.14081031] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Postmortem studies in schizophrenia reveal alterations in gene products that regulate the release and extracellular persistence of GABA. However, results of in vivo studies of schizophrenia measuring total tissue GABA with magnetic resonance spectroscopy (MRS) have been inconsistent. Neither the postmortem nor the MRS studies directly address the physiological properties of GABA neurotransmission. The present study addresses this question through an innovative positron emission tomography (PET) paradigm. METHOD The binding of [(11)C]flumazenil, a benzodiazepine-specific PET radiotracer, was measured before and after administration of tiagabine (0.2 mg/kg of body weight), a GABA membrane transporter (GAT1) blocker, in 17 off-medication patients with schizophrenia and 22 healthy comparison subjects. Increased extracellular GABA, through GAT1 blockade, enhances the affinity of GABAA receptors for benzodiazepine ligands, detected as an increase in [(11)C]flumazenil tissue distribution volume (VT). RESULTS [(11)C]Flumazenil VT was significantly increased across all cortical brain regions in the healthy comparison group but not in the schizophrenia group. This lack of effect was most prominent in the antipsychotic-naive schizophrenia group. In this subgroup, [(11)C]flumazenil ΔVT in the medial temporal lobe was correlated with positive symptoms, and baseline [(11)C]flumazenil VT in the medial temporal lobe was negatively correlated with visual learning. In the healthy comparison group but not the schizophrenia group, [(11)C]flumazenil ΔVT was positively associated with gamma-band oscillation power. CONCLUSIONS This study demonstrates, for the first time, an in vivo impairment in GABA transmission in schizophrenia, most prominent in antipsychotic-naive individuals. The impairment in GABA transmission appears to be linked to clinical symptoms, disturbances in cortical oscillations, and cognition.
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Gonzalez-Burgos G, Cho RY, Lewis DA. Alterations in cortical network oscillations and parvalbumin neurons in schizophrenia. Biol Psychiatry 2015; 77:1031-40. [PMID: 25863358 PMCID: PMC4444373 DOI: 10.1016/j.biopsych.2015.03.010] [Citation(s) in RCA: 352] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 02/09/2015] [Accepted: 03/07/2015] [Indexed: 11/17/2022]
Abstract
Cognitive deficits are a core clinical feature of schizophrenia but respond poorly to available medications. Thus, understanding the neural basis of these deficits is crucial for the development of new therapeutic interventions. The types of cognitive processes affected in schizophrenia are thought to depend on the precisely timed transmission of information in cortical regions via synchronous oscillations at gamma band frequency. Here, we review 1) data from clinical studies suggesting that induction of frontal cortex gamma oscillations during tasks that engage cognitive or complex perceptual functions is attenuated in schizophrenia; 2) findings from basic neuroscience studies highlighting the features of parvalbumin-positive interneurons that are critical for gamma oscillation production; and 3) results from recent postmortem human brain studies providing additional molecular bases for parvalbumin-positive interneuron alterations in prefrontal cortical circuitry in schizophrenia.
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Affiliation(s)
| | - Raymond Y Cho
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston, Houston, Texas
| | - David A Lewis
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburg, Pennsylvania.
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DeLorenzo C, DellaGioia N, Bloch M, Sanacora G, Nabulsi N, Abdallah C, Yang J, Wen R, Mann JJ, Krystal JH, Parsey RV, Carson RE, Esterlis I. In vivo ketamine-induced changes in [¹¹C]ABP688 binding to metabotropic glutamate receptor subtype 5. Biol Psychiatry 2015; 77:266-275. [PMID: 25156701 PMCID: PMC4277907 DOI: 10.1016/j.biopsych.2014.06.024] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/17/2014] [Accepted: 06/23/2014] [Indexed: 01/23/2023]
Abstract
BACKGROUND At subanesthetic doses, ketamine, an N-methyl-D-aspartate glutamate receptor antagonist, increases glutamate release. We imaged the acute effect of ketamine on brain metabotropic glutamatergic receptor subtype 5 with a high-affinity positron emission tomography (PET) ligand [(11)C]ABP688 (E)-3-[2-(6-methyl-2-pyridinyl)ethynyl]-2-cyclohexen-1-one-O-(methyl-11C)oxime, a negative allosteric modulator of the metabotropic glutamatergic receptor subtype 5. METHODS Two [(11)C]ABP688 PET scans were performed in 10 healthy nonsmoking human volunteers (34 ± 13 years old); the two PET scans were performed on the same day-before (scan 1) and during intravenous ketamine administration (.23 mg/kg over 1 min, then .58 mg/kg over 1 hour; scan 2). The PET data were acquired for 90 min immediately after [(11)C]ABP688 bolus injection. Input functions were obtained through arterial blood sampling with metabolite analysis. RESULTS A significant reduction in [(11)C]ABP688 volume of distribution was observed in scan 2 relative to scan 1 of 21.3% ± 21.4%, on average, in the anterior cingulate, medial prefrontal cortex, orbital prefrontal cortex, ventral striatum, parietal lobe, dorsal putamen, dorsal caudate, amygdala, and hippocampus. There was a significant increase in measurements of dissociative state after ketamine initiation (p < .05), which resolved after completion of the scan. CONCLUSIONS This study provides first evidence that ketamine administration decreases [(11)C]ABP688 binding in vivo in human subjects. The results suggest that [(11)C]ABP688 binding is sensitive to ketamine-induced effects, although the high individual variation in ketamine response requires further examination.
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Affiliation(s)
- Christine DeLorenzo
- Departments of Psychiatry, Stony Brook University, Stony Brook, New York, New York; Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York, New York.
| | | | - Michael Bloch
- Department of Psychiatry, Diagnostic, Yale University,Department of Child Study Center, Yale University
| | | | | | - Chadi Abdallah
- Department of Psychiatry, Diagnostic, Yale University,Clinical Neuroscience Division, VA National Center for PTSD
| | - Jie Yang
- Department of Preventive Medicine, Stony Brook University
| | - Ruofeng Wen
- Department of Applied Mathematics and Statistics, Stony Brook University
| | | | - John H. Krystal
- Department of Psychiatry, Diagnostic, Yale University,Clinical Neuroscience Division, VA National Center for PTSD
| | - Ramin V. Parsey
- Department of Psychiatry, Stony Brook University,Department of Radiology, Stony Brook University
| | - Richard E. Carson
- Department of Radiology, Biomedical, Yale University,Department of Engineering, Yale University
| | - Irina Esterlis
- Department of Psychiatry, Diagnostic, Yale University,Department of Child Study Center, Yale University
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Finnema SJ, Scheinin M, Shahid M, Lehto J, Borroni E, Bang-Andersen B, Sallinen J, Wong E, Farde L, Halldin C, Grimwood S. Application of cross-species PET imaging to assess neurotransmitter release in brain. Psychopharmacology (Berl) 2015; 232:4129-57. [PMID: 25921033 PMCID: PMC4600473 DOI: 10.1007/s00213-015-3938-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/09/2015] [Indexed: 01/03/2023]
Abstract
RATIONALE This review attempts to summarize the current status in relation to the use of positron emission tomography (PET) imaging in the assessment of synaptic concentrations of endogenous mediators in the living brain. OBJECTIVES Although PET radioligands are now available for more than 40 CNS targets, at the initiation of the Innovative Medicines Initiative (IMI) "Novel Methods leading to New Medications in Depression and Schizophrenia" (NEWMEDS) in 2009, PET radioligands sensitive to an endogenous neurotransmitter were only validated for dopamine. NEWMEDS work-package 5, "Cross-species and neurochemical imaging (PET) methods for drug discovery", commenced with a focus on developing methods enabling assessment of changes in extracellular concentrations of serotonin and noradrenaline in the brain. RESULTS Sharing the workload across institutions, we utilized in vitro techniques with cells and tissues, in vivo receptor binding and microdialysis techniques in rodents, and in vivo PET imaging in non-human primates and humans. Here, we discuss these efforts and review other recently published reports on the use of radioligands to assess changes in endogenous levels of dopamine, serotonin, noradrenaline, γ-aminobutyric acid, glutamate, acetylcholine, and opioid peptides. The emphasis is on assessment of the availability of appropriate translational tools (PET radioligands, pharmacological challenge agents) and on studies in non-human primates and human subjects, as well as current challenges and future directions. CONCLUSIONS PET imaging directed at investigating changes in endogenous neurochemicals, including the work done in NEWMEDS, have highlighted an opportunity to further extend the capability and application of this technology in drug development.
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Affiliation(s)
- Sjoerd J. Finnema
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Mika Scheinin
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland , />Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
| | - Mohammed Shahid
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Jussi Lehto
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
| | - Edilio Borroni
- />Neuroscience Department, Hoffman-La Roche, Basel, Switzerland
| | | | - Jukka Sallinen
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Erik Wong
- />Neuroscience Innovative Medicine Unit, AstraZeneca, Wilmington, DE USA
| | - Lars Farde
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden , />Translational Science Center at Karolinska Institutet, AstraZeneca, Stockholm, Sweden
| | - Christer Halldin
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Sarah Grimwood
- Neuroscience Research Unit, Pfizer Inc, Cambridge, MA, USA. .,, 610 Main Street, Cambridge, MA, 02139, USA.
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Quelch D, De Santis V, Strege A, Myers J, Wells L, Nutt D, Lingford-Hughes A, Parker C, Tyacke R. Influence of agonist induced internalization on [3H]Ro15-4513 binding-an application to imaging fluctuations in endogenous GABA with positron emission tomography. Synapse 2014; 69:60-5. [DOI: 10.1002/syn.21780] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/12/2014] [Accepted: 08/27/2014] [Indexed: 02/05/2023]
Affiliation(s)
- Darren Quelch
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | | | | | - James Myers
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | - Lisa Wells
- Imanova Centro for Imaging Sciences; London UK
| | - David Nutt
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | - Anne Lingford-Hughes
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | | | - Robin Tyacke
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
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Stokes PRA, Myers JF, Kalk NJ, Watson BJ, Erritzoe D, Wilson SJ, Cunningham VJ, Riano Barros D, Hammers A, Turkheimer FE, Nutt DJ, Lingford-Hughes AR. Acute increases in synaptic GABA detectable in the living human brain: a [¹¹C]Ro15-4513 PET study. Neuroimage 2014; 99:158-65. [PMID: 24844747 DOI: 10.1016/j.neuroimage.2014.05.035] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/24/2014] [Accepted: 05/12/2014] [Indexed: 10/25/2022] Open
Abstract
The inhibitory γ-aminobutyric acid (GABA) neurotransmitter system is associated with the regulation of normal cognitive functions and dysregulation has been reported in a number of neuropsychiatric disorders including anxiety disorders, schizophrenia and addictions. Investigating the role of GABA in both health and disease has been constrained by difficulties in measuring acute changes in synaptic GABA using neurochemical imaging. The aim of this study was to investigate whether acute increases in synaptic GABA are detectable in the living human brain using the inverse agonist GABA-benzodiazepine receptor (GABA-BZR) positron emission tomography (PET) tracer, [(11)C]Ro15-4513. We examined the effect of 15 mg oral tiagabine, which increases synaptic GABA by inhibiting the GAT1 GABA uptake transporter, on [(11)C]Ro15-4513 binding in 12 male participants using a paired, double blind, placebo-controlled protocol. Spectral analysis was used to examine synaptic α1 and extrasynaptic α5 GABA-BZR subtype availability in brain regions with high levels of [(11)C]Ro15-4513 binding. We also examined the test-retest reliability of α1 and a5-specific [(11)C]Ro15-4513 binding in a separate cohort of 4 participants using the same spectral analysis protocol. Tiagabine administration produced significant reductions in hippocampal, parahippocampal, amygdala and anterior cingulate synaptic α1 [(11)C]Ro15-4513 binding, and a trend significance reduction in the nucleus accumbens. These reductions were greater than test-retest reliability, indicating that they are not the result of chance observations. Our results suggest that acute increases in endogenous synaptic GABA are detectable in the living human brain using [(11)C]Ro15-4513 PET. These findings have potentially major implications for the investigation of GABA function in brain disorders and in the development of new treatments targeting this neurotransmitter system.
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Affiliation(s)
- Paul R A Stokes
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK; Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, King's College London, London SE5 8AF, UK.
| | - Jim F Myers
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK; Psychopharmacology Unit, School of Social and Community Medicine, University of Bristol, Oakfield House, BS8 2BN, UK
| | - Nicola J Kalk
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK
| | - Ben J Watson
- Psychopharmacology Unit, School of Social and Community Medicine, University of Bristol, Oakfield House, BS8 2BN, UK
| | - David Erritzoe
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK
| | - Sue J Wilson
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK; Psychopharmacology Unit, School of Social and Community Medicine, University of Bristol, Oakfield House, BS8 2BN, UK
| | - Vincent J Cunningham
- School of Medical Sciences, University of Aberdeen, IMS Building, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Daniela Riano Barros
- MRC Clinical Sciences Centre and Division of Medicine, Imperial College London, Hammersmith Hospital, UK
| | - Alexander Hammers
- MRC Clinical Sciences Centre and Division of Medicine, Imperial College London, Hammersmith Hospital, UK; The Neurodis Foundation, CERMEP Imagerie du Vivant, Lyon, France
| | - Federico E Turkheimer
- Centre for Neuroimaging Sciences, Institute of Psychiatry, PO89, De Crespigny Park, London SE5 8AF, UK
| | - David J Nutt
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK
| | - Anne R Lingford-Hughes
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Burlington Danes Building, Imperial College London, W12 0NN, UK
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Kang JI, Park HJ, Kim SJ, Kim KR, Lee SY, Lee E, An SK, Kwon JS, Lee JD. Reduced binding potential of GABA-A/benzodiazepine receptors in individuals at ultra-high risk for psychosis: an [18F]-fluoroflumazenil positron emission tomography study. Schizophr Bull 2014; 40:548-57. [PMID: 23588475 PMCID: PMC3984508 DOI: 10.1093/schbul/sbt052] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Altered transmission of gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter, may contribute to the development of schizophrenia. The purpose of the present study was to investigate the presence of GABA-A/benzodiazepine (BZ) receptor binding abnormalities in individuals at ultra-high risk (UHR) for psychosis in comparison with normal controls using [(18)F]-fluoroflumazenil (FFMZ) positron emission tomography (PET). In particular, we set regions of interest in the striatum (caudate, putamen, and nucleus accumbens) and medial temporal area (hippocampus and parahippocampal gyrus). METHODS Eleven BZ-naive people at UHR and 15 normal controls underwent PET scanning using [(18)F]-FFMZ to measure GABA-A/BZ receptor binding potential. The regional group differences between UHR individuals and normal controls were analyzed using Statistical Parametric Mapping 8 software. Participants were evaluated using the structured interview for prodromal syndromes and neurocognitive function tasks. RESULTS People at UHR demonstrated significantly reduced binding potential of GABA-A/BZ receptors in the right caudate. CONCLUSIONS Altered GABAergic transmission and/or the imbalance of inhibitory and excitatory systems in the striatum may be present at the putative prodromal stage and play a pivotal role in the pathophysiology of psychosis.
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Affiliation(s)
- Jee In Kang
- *To whom correspondence should be addressed; Department of Psychiatry, Severance Mental Health Hospital, Yonsei University Health System, 119, 1926 Beon-gil, Gyeongchung-daero, Gwangju-si, Gyeonggi-do 464-100, South Korea; tel: +82-31-760-9404, fax: +82-31-761-7582, e-mail:
| | - Hae-Jeong Park
- Department of Psychiatry, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea;,Department of Medical Science, Yonsei University College of Medicine, Seoul, South Korea;,Department of Nuclear Medicine, BK21 Project for Medical Science, and Severance Biomedical Science Institute, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea;,†These two authors contributed equally to this work and should be considered co-first authors
| | - Se Joo Kim
- Department of Psychiatry, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea;,Clinical and Neurobiological Lab for Obsessive-Compulsive Disorder, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, South Korea;,Department of Medical Science, Yonsei University College of Medicine, Seoul, South Korea
| | - Kyung Ran Kim
- Department of Psychiatry, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea;,Section of Affect and Neuroscience, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Su Young Lee
- Section of Affect and Neuroscience, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, South Korea;,Department of Psychiatry, Cheil General Hospital & Women’s Healthcare Center, Kwandong University College of Medicine, Seoul, South Korea
| | - Eun Lee
- Department of Psychiatry, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea;,Section of Affect and Neuroscience, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Suk Kyoon An
- Section of Affect and Neuroscience, Institute of Behavioral Science in Medicine, Yonsei University College of Medicine, Seoul, South Korea;,Department of Medical Science, Yonsei University College of Medicine, Seoul, South Korea;,Department of Psychiatry, Yonsei University College of Medicine, Severance Mental Health Hospital, Seoul, South Korea;,Graduate Program in Cognitive Science, Yonsei University, Seoul, South Korea;,*To whom correspondence should be addressed; Department of Psychiatry, Severance Mental Health Hospital, Yonsei University Health System, 119, 1926 Beon-gil, Gyeongchung-daero, Gwangju-si, Gyeonggi-do 464-100, South Korea; tel: +82-31-760-9404, fax: +82-31-761-7582, e-mail:
| | - Jun Soo Kwon
- Department of Psychiatry, Seoul National University College of Medicine, Seoul, South Korea
| | - Jong Doo Lee
- Department of Nuclear Medicine, BK21 Project for Medical Science, and Severance Biomedical Science Institute, Yonsei University College of Medicine, Severance Hospital, Seoul, South Korea
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Duncan NW, Wiebking C, Muñoz-Torres Z, Northoff G. How to investigate neuro-biochemical relationships on a regional level in humans? Methodological considerations for combining functional with biochemical imaging. J Neurosci Methods 2014. [DOI: 10.1016/j.jneumeth.2013.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Sandiego CM, Jin X, Mulnix T, Fowles K, Labaree D, Ropchan J, Huang Y, Cosgrove K, Castner SA, Williams GV, Wells L, Rabiner EA, Carson RE. Awake nonhuman primate brain PET imaging with minimal head restraint: evaluation of GABAA-benzodiazepine binding with 11C-flumazenil in awake and anesthetized animals. J Nucl Med 2013; 54:1962-8. [PMID: 24115528 DOI: 10.2967/jnumed.113.122077] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Neuroreceptor imaging in the nonhuman primate (NHP) is valuable for translational research approaches in humans. However, most NHP studies are conducted under anesthesia, which affects the interpretability of receptor binding measures. The aims of this study were to develop awake NHP imaging with minimal head restraint and to compare in vivo binding of the γ-aminobutyric acid type A (GABAA)-benzodiazepine radiotracer (11)C-flumazenil under anesthetized and awake conditions. We hypothesized that (11)C-flumazenil binding potential (BPND) would be higher in isoflurane-anesthetized monkeys. METHODS The small animal PET scanner was fitted to a mechanical device that raised and tilted the scanner 45° while the awake NHP was tilted back 35° in a custom chair for optimal brain positioning, which required acclimation of the animals to the chair, touch-screen tasks, intravenous catheter insertion, and tilting. For PET studies, the bolus-plus-constant infusion method was used for (11)C-flumazenil administration. Two rhesus monkeys were scanned under the awake (n = 6 scans) and isoflurane-anesthetized (n = 4 scans) conditions. An infrared camera was used to track head motion during PET scans. Under the awake condition, emission and head motion-tracking data were acquired for 40-75 min after injection. Anesthetized monkeys were scanned for 90 min. Cortisol measurements were acquired during awake and anesthetized scans. Equilibrium analysis was used for both the anesthetized (n = 4) and the awake (n = 5) datasets to compute mean BPND images in NHP template space, using the pons as a reference region. The percentage change per minute in radioactivity concentration was calculated in high- and low-binding regions to assess the quality of equilibrium. RESULTS The monkeys acclimated to procedures in the NHP chair necessary to perform awake PET imaging. Image quality was comparable between awake and anesthetized conditions. The relationship between awake and anesthetized values was BPND (awake) = 0.94 BPND (anesthetized) + 0.36 (r(2) = 0.95). Cortisol levels were significantly higher under the awake condition (P < 0.05). CONCLUSION We successfully performed awake NHP imaging with minimal head restraint. There was close agreement in (11)C-flumazenil BPND values between awake and anesthetized conditions.
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Disrupting the clustering of GABAA receptor α2 subunits in the frontal cortex leads to reduced γ-power and cognitive deficits. Proc Natl Acad Sci U S A 2013; 110:16628-33. [PMID: 24043839 DOI: 10.1073/pnas.1308706110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In schizophrenia, cognitive dysfunction is highly predictive of poor patient outcomes and is not responsive to current medications. Postmortem studies have suggested that cognitive deficits in schizophrenia are correlated with modifications in the number and size of inhibitory synapses. To test if these modifications lead to cognitive deficits, we have created a dominant-negative virus [adeno-associated (AAV)-DN1] that disrupts the clustering of γ-aminobutyric acid type A receptors (GABA(A)Rs) at postsynaptic inhibitory specializations. When injected into the frontal cortex of mice, AAV-DN1 impairs GABA(A)R α2 subunit and GABA transporter 1 (GAT-1) clustering, but increases GABA(A)R α1 subunit clustering on the perisomatic region, with no influence on axon-initial segment clustering. Mice expressing AAV-DN1 have prepulse inhibition deficits and impairments in working memory. Significantly, these behavioral deficits are paralleled by a reduction in electroencephalography γ-power. Collectively, our study provides functional evidence revealing that GABAergic synapses in the prefrontal cortex directly contribute to cognition and γ-power.
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Muthukumaraswamy SD, Myers JFM, Wilson SJ, Nutt DJ, Hamandi K, Lingford-Hughes A, Singh KD. Elevating endogenous GABA levels with GAT-1 blockade modulates evoked but not induced responses in human visual cortex. Neuropsychopharmacology 2013; 38:1105-12. [PMID: 23361120 PMCID: PMC3629410 DOI: 10.1038/npp.2013.9] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 11/13/2012] [Accepted: 11/26/2012] [Indexed: 02/01/2023]
Abstract
The electroencephalographic/magnetoencephalographic (EEG/MEG) signal is generated primarily by the summation of the postsynaptic currents of cortical principal cells. At a microcircuit level, these glutamatergic principal cells are reciprocally connected to GABAergic interneurons. Here we investigated the relative sensitivity of visual evoked and induced responses to altered levels of endogenous GABAergic inhibition. To do this, we pharmacologically manipulated the GABA system using tiagabine, which blocks the synaptic GABA transporter 1, and so increases endogenous GABA levels. In a single-blinded and placebo-controlled crossover study of 15 healthy participants, we administered either 15 mg of tiagabine or a placebo. We recorded whole-head MEG, while participants viewed a visual grating stimulus, before, 1, 3 and 5 h post tiagabine ingestion. Using beamformer source localization, we reconstructed responses from early visual cortices. Our results showed no change in either stimulus-induced gamma-band amplitude increases or stimulus-induced alpha amplitude decreases. However, the same data showed a 45% reduction in the evoked response component at ∼80 ms. These data demonstrate that, in early visual cortex the evoked response shows a greater sensitivity compared with induced oscillations to pharmacologically increased endogenous GABA levels. We suggest that previous studies correlating GABA concentrations as measured by magnetic resonance spectroscopy to gamma oscillation frequency may reflect underlying variations such as interneuron/inhibitory synapse density rather than functional synaptic GABA concentrations.
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Andersson JD, Halldin C. PET radioligands targeting the brain GABAA/benzodiazepine receptor complex. J Labelled Comp Radiopharm 2013; 56:196-206. [DOI: 10.1002/jlcr.3008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 11/15/2012] [Accepted: 11/16/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Jan D. Andersson
- Department of Clinical Neuroscience; Center for Psychiatric Research and Education, Karolinska Institutet; Stockholm; Sweden
| | - Christer Halldin
- Department of Clinical Neuroscience; Center for Psychiatric Research and Education, Karolinska Institutet; Stockholm; Sweden
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Qin P, Duncan NW, Wiebking C, Gravel P, Lyttelton O, Hayes DJ, Verhaeghe J, Kostikov A, Schirrmacher R, Reader AJ, Northoff G. GABA(A) receptors in visual and auditory cortex and neural activity changes during basic visual stimulation. Front Hum Neurosci 2012; 6:337. [PMID: 23293594 PMCID: PMC3533380 DOI: 10.3389/fnhum.2012.00337] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 12/07/2012] [Indexed: 11/13/2022] Open
Abstract
Recent imaging studies have demonstrated that levels of resting γ-aminobutyric acid (GABA) in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABA(A) receptors, in the changes in brain activity between the eyes closed (EC) and eyes open (EO) state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: an EO and EC block design, allowing the modeling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [(18)F]Flumazenil PET to measure GABA(A) receptor binding potentials. It was demonstrated that the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABA(A) receptor binding potential in the visual cortex also predicted the change in functional connectivity between the visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABA(A) receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.
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Affiliation(s)
- Pengmin Qin
- Mind, Brain Imaging and Neuroethics, University of Ottawa Institute of Mental Health Research Ottawa, ON, Canada
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Volk DW, Matsubara T, Li S, Sengupta EJ, Georgiev D, Minabe Y, Sampson A, Hashimoto T, Lewis DA. Deficits in transcriptional regulators of cortical parvalbumin neurons in schizophrenia. Am J Psychiatry 2012; 169:1082-91. [PMID: 22983435 PMCID: PMC3513625 DOI: 10.1176/appi.ajp.2012.12030305] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE In schizophrenia, alterations within the prefrontal cortical GABA system appear to be most prominent in neurons that contain parvalbumin or somatostatin but not calretinin. The transcription factors Lhx6 and Sox6 play critical roles in the specification, migration, and maturation of parvalbumin and somatostatin neurons, but not calretinin neurons, and continue to be strongly expressed in this cell type-specific manner in the prefrontal cortex of adult humans. The authors investigated whether Lhx6 and/or Sox6 mRNA levels are deficient in schizophrenia, which may contribute to cell type-specific disturbances in cortical parvalbumin and somatostatin neurons. METHOD The authors used quantitative PCR and in situ hybridization with film and grain counting analyses to quantify mRNA levels in postmortem samples of prefrontal cortex area 9 of 42 schizophrenia subjects and 42 comparison subjects who had no psychiatric diagnoses in life, as well as antipsychotic-exposed monkeys. RESULTS In schizophrenia subjects, the authors observed lower mRNA levels for Lhx6, parvalbumin, somatostatin, and glutamate decarboxylase (GAD67; the principal enzyme in GABA synthesis), but not Sox6 or calretinin. Cluster analysis revealed that a subset of schizophrenia subjects consistently showed the most severe deficits in the affected transcripts. Grain counting analyses revealed that some neurons that normally express Lhx6 were not detectable in schizophrenia subjects. Finally, lower Lhx6 mRNA levels were not attributable to psychotropic medications or illness chronicity. CONCLUSIONS These data suggest that in a subset of individuals with schizophrenia, Lhx6 deficits may contribute to a failure of some cortical parvalbumin and somatostatin neurons to successfully migrate or develop a detectable GABA-ergic phenotype.
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Wiebking C, Duncan NW, Qin P, Hayes DJ, Lyttelton O, Gravel P, Verhaeghe J, Kostikov AP, Schirrmacher R, Reader AJ, Bajbouj M, Northoff G. External awareness and GABA--a multimodal imaging study combining fMRI and [18F]flumazenil-PET. Hum Brain Mapp 2012; 35:173-84. [PMID: 22996793 DOI: 10.1002/hbm.22166] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 05/19/2012] [Accepted: 06/22/2012] [Indexed: 11/10/2022] Open
Abstract
Awareness is an essential feature of the human mind that can be directed internally, that is, toward our self, or externally, that is, toward the environment. The combination of internal and external information is crucial to constitute our sense of self. Although the underlying neuronal networks, the so-called intrinsic and extrinsic systems, have been well-defined, the associated biochemical mechanisms still remain unclear. We used a well-established functional magnetic resonance imaging (fMRI) paradigm for internal (heartbeat counting) and external (tone counting) awareness and combined this technique with [(18)F]FMZ-PET imaging in the same healthy subjects. Focusing on cortical midline regions, the results showed that both stimuli types induce negative BOLD responses in the mPFC and the precuneus. Carefully controlling for structured noise in fMRI data, these results were also confirmed in an independent data sample using the same paradigm. Moreover, the degree of the GABAA receptor binding potential within these regions was correlated with the neuronal activity changes associated with external, rather than internal awareness when compared to fixation. These data support evidence that the inhibitory neurotransmitter GABA is an influencing factor in the differential processing of internally and externally guided awareness. This in turn has implications for our understanding of the biochemical mechanisms underlying awareness in general and its potential impact on psychiatric disorders.
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Affiliation(s)
- Christine Wiebking
- Department of Biology, Freie Universität Berlin, Berlin, Germany; Institute of Mental Health Research, University of Ottawa, Ontario, Canada
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Laymon CM, Narendran R, Mason NS, Carney JP, Lopresti BJ, Mathis CA, Mountz JM, Sashin D, Frankle WG. Human biodistribution and dosimetry of the PET radioligand [¹¹C]flumazenil (FMZ). Mol Imaging Biol 2012; 14:115-22. [PMID: 21365327 DOI: 10.1007/s11307-011-0478-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE We measure the whole-body distribution of IV injected [¹¹C]Flumazenil (FMZ) as a function of time in adult subjects and determine the absorbed radiation doses. PROCEDURES After injection with 770 MBq of [¹¹C]FMZ (nominal), each of six subjects underwent nine consecutive whole body PET scans. Twelve source organs were identified using PET attenuation and emission images. Activity within each organ as a function of time was determined from the sequence of the nine PET scans. Source organ time activity curves were integrated and normalized by the injected dose to yield source organ residence times for the no voiding situation. Separate bladder residence-time calculations were performed for the cases of a 1- and a 2-h voiding interval. Using the source organ residence times as input, the program OLINDA/EXM (Stabin et al. in J Nucl Med. 46:1023-1027, 2005) was used to perform dosimetry calculations for the various body organs and for the whole body. RESULTS For the no voiding situation, the average whole-body radiation equivalent dose was 3.02 × 10⁻³ mSv/MBq of injected [¹¹C]FMZ. The average effective dose and effective dose equivalent was 7.57 × 10⁻³ and 1.12 × 10⁻² mSv MBq⁻¹, respectively. The organ receiving the highest equivalent dose was the urinary bladder wall with an average of 6.32 × 10⁻² mSv MBq⁻¹. CONCLUSION On average, the administration of less than 790 MBq (21 mCi) of [¹¹C]FMZ yields (no voiding model) an organ equivalent dose of under 50 mSv [the single dose limit for research studies under US regulations (21CFR361.1) to body organs other than blood forming organs, gonads or the lens of the eye] to all organs. Equivalent dose to the blood forming organs and gonads from a 790 MBq administered FMZ dose is well under the 30 mSv limit provided under 21CFR361.1. Additionally, administration of less than 1320 MBq (35.7 mCi) yields an effective dose [International Commission on Radiation Protection (ICRP) 60 tissue weighting scheme] of under 10 mSv, which is the ICRP IIb (minor to intermediate) risk category limit.
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Affiliation(s)
- Charles M Laymon
- Department of Radiology, UPMC/Presbyterian Hospital, University of Pittsburgh, Room B-938, 200 Lothrop St., Pittsburgh, PA 15213, USA.
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Abstract
The early developments of brain positron emission tomography (PET), including the methodological advances that have driven progress, are outlined. The considerable past achievements of brain PET have been summarized in collaboration with contributing experts in specific clinical applications including cerebrovascular disease, movement disorders, dementia, epilepsy, schizophrenia, addiction, depression and anxiety, brain tumors, drug development, and the normal healthy brain. Despite a history of improving methodology and considerable achievements, brain PET research activity is not growing and appears to have diminished. Assessments of the reasons for decline are presented and strategies proposed for reinvigorating brain PET research. Central to this is widening the access to advanced PET procedures through the introduction of lower cost cyclotron and radiochemistry technologies. The support and expertize of the existing major PET centers, and the recruitment of new biologists, bio-mathematicians and chemists to the field would be important for such a revival. New future applications need to be identified, the scope of targets imaged broadened, and the developed expertize exploited in other areas of medical research. Such reinvigoration of the field would enable PET to continue making significant contributions to advance the understanding of the normal and diseased brain and support the development of advanced treatments.
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Affiliation(s)
- Terry Jones
- PET Research Advisory Company, 8 Prestbury Road, Wilmslow, Cheshire SK9 2LJ, UK.
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Lerner A, Bagic A, Simmons JM, Mari Z, Bonne O, Xu B, Kazuba D, Herscovitch P, Carson RE, Murphy DL, Drevets WC, Hallett M. Widespread abnormality of the γ-aminobutyric acid-ergic system in Tourette syndrome. ACTA ACUST UNITED AC 2012; 135:1926-36. [PMID: 22577221 DOI: 10.1093/brain/aws104] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dysfunction of the γ-aminobutyric acid-ergic system in Tourette syndrome may conceivably underlie the symptoms of motor disinhibition presenting as tics and psychiatric manifestations, such as attention deficit hyperactivity disorder and obsessive-compulsive disorder. The purpose of this study was to identify a possible dysfunction of the γ-aminobutyric acid-ergic system in Tourette patients, especially involving the basal ganglia-thalamo-cortical circuits and the cerebellum. We studied 11 patients with Tourette syndrome and 11 healthy controls. Positron emission tomography procedure: after injection of 20 mCi of [(11)C]flumazenil, dynamic emission images of the brain were acquired. Structural magnetic resonance imaging scans were obtained to provide an anatomical framework for the positron emission tomography data analysis. Images of binding potential were created using the two-step version of the simplified reference tissue model. The binding potential images then were spatially normalized, smoothed and compared between groups using statistical parametric mapping. We found decreased binding of GABA(A) receptors in Tourette patients bilaterally in the ventral striatum, globus pallidus, thalamus, amygdala and right insula. In addition, the GABA(A) receptor binding was increased in the bilateral substantia nigra, left periaqueductal grey, right posterior cingulate cortex and bilateral cerebellum. These results are consistent with the longstanding hypothesis that circuits involving the basal ganglia and thalamus are disinhibited in Tourette syndrome patients. In addition, the abnormalities in GABA(A) receptor binding in the insula and cerebellum appear particularly noteworthy based upon recent evidence implicating these structures in the generation of tics.
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Affiliation(s)
- Alicja Lerner
- Controlled Substance Staff, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland 20993, USA.
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Frankle WG, Cho RY, Mason NS, Chen CM, Himes M, Walker C, Lewis DA, Mathis CA, Narendran R. [11C]flumazenil binding is increased in a dose-dependent manner with tiagabine-induced elevations in GABA levels. PLoS One 2012; 7:e32443. [PMID: 22384252 PMCID: PMC3288104 DOI: 10.1371/journal.pone.0032443] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 01/26/2012] [Indexed: 01/14/2023] Open
Abstract
Evidence indicates that synchronization of cortical activity at gamma-band frequencies, mediated through GABA-A receptors, is important for perceptual/cognitive processes. To study GABA signaling in vivo, we recently used a novel positron emission tomography (PET) paradigm measuring the change in binding of the benzodiazepine (BDZ) site radiotracer [11C]flumazenil associated with increases in extracellular GABA induced via GABA membrane transporter (GAT1) blockade with tiagabine. GAT1 blockade resulted in significant increases in [11C]flumazenil binding potential (BPND) over baseline in the major functional domains of the cortex, consistent with preclinical studies showing that increased GABA levels enhance the affinity of GABA-A receptors for BDZ ligands. In the current study we sought to replicate our previous results and to further validate this approach by demonstrating that the magnitude of increase in [11C]flumazenil binding observed with PET is directly correlated with tiagabine dose. [11C]flumazenil distribution volume (VT) was measured in 18 healthy volunteers before and after GAT1 blockade with tiagabine. Two dose groups were studied (n = 9 per group; Group I: tiagabine 0.15 mg/kg; Group II: tiagabine 0.25 mg/kg). GAT1 blockade resulted in increases in mean (± SD) [11C]flumazenil VT in Group II in association cortices (6.8±0.8 mL g−1 vs. 7.3±0.4 mL g−1;p = 0.03), sensory cortices (6.7±0.8 mL g−1 vs. 7.3±0.5 mL g−1;p = 0.02) and limbic regions (5.2±0.6 mL g−1 vs. 5.7±0.3 mL g−1;p = 0.03). No change was observed at the low dose (Group I). Increased orbital frontal cortex binding of [11C]flumazenil in Group II correlated with the ability to entrain cortical networks (r = 0.67, p = 0.05) measured via EEG during a cognitive control task. These data provide a replication of our previous study demonstrating the ability to measure in vivo, with PET, acute shifts in extracellular GABA.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
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Measuring Dopamine Synaptic Transmission with Molecular Imaging and Pharmacological Challenges: The State of the Art. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_45] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Lewis DA, Curley AA, Glausier JR, Volk DW. Cortical parvalbumin interneurons and cognitive dysfunction in schizophrenia. Trends Neurosci 2011; 35:57-67. [PMID: 22154068 DOI: 10.1016/j.tins.2011.10.004] [Citation(s) in RCA: 782] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 10/07/2011] [Accepted: 10/24/2011] [Indexed: 12/21/2022]
Abstract
Deficits in cognitive control, a core disturbance of schizophrenia, appear to emerge from impaired prefrontal gamma oscillations. Cortical gamma oscillations require strong inhibitory inputs to pyramidal neurons from the parvalbumin basket cell (PVBC) class of GABAergic neurons. Recent findings indicate that schizophrenia is associated with multiple pre- and postsynaptic abnormalities in PVBCs, each of which weakens their inhibitory control of pyramidal cells. These findings suggest a new model of cortical dysfunction in schizophrenia in which PVBC inhibition is decreased to compensate for an upstream deficit in pyramidal cell excitation. This compensation is thought to rebalance cortical excitation and inhibition, but at a level insufficient to generate the gamma oscillation power required for high levels of cognitive control.
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Affiliation(s)
- David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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Gaetz W, Roberts TPL, Singh KD, Muthukumaraswamy SD. Functional and structural correlates of the aging brain: relating visual cortex (V1) gamma band responses to age-related structural change. Hum Brain Mapp 2011; 33:2035-46. [PMID: 21769992 DOI: 10.1002/hbm.21339] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 04/06/2011] [Accepted: 04/08/2011] [Indexed: 11/06/2022] Open
Abstract
The gamma band response is thought to be a key neural signature of information processing in the mammalian brain, yet little is known about how age-related maturation influences the γ-band response. Recent MRI-based studies have shown that brain maturation is accompanied by clear structural changes in both gray and white matter, yet the correspondence of these changes to brain function is unclear. The objective of this study was to relate visual cortex (V1) γ-band responses to age-related structural change. We evaluated MEG measured γ-band responses to contrast gratings stimuli and structural MRIs from participants observed from two separate research centers (MEG lab at CUBRIC, Cardiff University, UK, and the Lurie Family Foundations MEG Imaging Center, (CHOP) at the Children's Hospital of Philadelphia). Pooled participant data (N = 59) ranged in age from 8.7 to 45.3 years. We assessed linear associations between age and MEG γ-band frequency and amplitude, as well as between age and MRI volumetric parameters of the occipital lobe. Our MEG findings revealed a significant negative correlation for gamma band frequency versus age. Volumetric brain analysis from the occipital lobe also revealed significant negative correlations between age and the cortical thickness of pericalcarine and cuneus areas. Our functional MEG and structural MRI findings shows regionally specific changes due to maturation and may thus be informative for understanding physiological processes of neural development, maturation, and age-related decline. In addition, this study represents (to our knowledge), the first published demonstration of multicenter data sharing across MEG centers.
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Affiliation(s)
- William Gaetz
- Lurie Family Foundations MEG Imaging Center, Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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Garibotto V, Romito LM, Elia AE, Soliveri P, Panzacchi A, Carpinelli A, Tinazzi M, Albanese A, Perani D. In vivo evidence for GABA(A) receptor changes in the sensorimotor system in primary dystonia. Mov Disord 2011; 26:852-7. [PMID: 21370265 DOI: 10.1002/mds.23553] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 10/05/2010] [Accepted: 11/01/2010] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Preclinical and clinical evidence suggests that impaired gamma-aminobutyric (GABA) control, leading to disinhibition within the sensorimotor system, might play a role in dystonia. Aim of this study is the in vivo assessment of the GABAergic system in dystonia using positron emission tomography (PET) and (11) C-flumazenil, a selective GABA(A) receptor ligand. METHODS Fourteen subjects with primary dystonia (9 carriers of the DYT1 mutation and 5 sporadic cases) were compared to 11 controls, using a simplified reference tissue model to measure binding potential. RESULTS Voxel-based analyses showed a reduction in GABA(A) receptor expression/affinity both in DYT1 carriers and sporadic patients in primary motor and premotor cortex, primary and secondary somatosensory cortex, and in the motor component of the cingulate gyrus. CONCLUSIONS Dysfunction of GABA(A) receptors in sensorimotor systems in primary (genetic and sporadic) dystonia supports the view that lack of GABAergic control may be associated with the generation of dystonic movements.
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Abstract
Molecular in vivo neuroimaging techniques can be used to measure regional changes in endogenous neurotransmitters, evoked by challenges that alter synaptic neurotransmitter concentration. This technique has most successfully been applied to the study of endogenous dopamine release using positron emission tomography, but has not yet been adequately extended to other neurotransmitter systems. This review focuses on how the technique has been applied to the study of the 5-hydroxytryptamine (5-HT) system. The principles behind visualising fluctuations in neurotransmitters are introduced, with reference to the dopaminergic system. Studies that aim to image acute, endogenous 5-HT release or depletion at 5-HT receptor targets are summarised, with particular attention to studies in humans. Radiotracers targeting the 5-HT(1A), 5-HT(2A), and 5-HT(4) receptors and the serotonin reuptake transporter have been explored for their sensitivity to 5-HT fluctuations, but with mixed outcomes; tracers for these targets cannot reliably image endogenous 5-HT in humans. Shortcomings in our basic knowledge of the mechanisms underlying changes in binding potential are addressed, and suggestions are made as to how the selection of targets, radiotracers, challenge paradigms, and experimental design might be optimised to improve our chances of successfully imaging endogenous neurotransmitters in the future.
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Abstract
The hypothesis that alterations of cortical inhibitory gamma-aminobutyric acid (GABA) neurons are a central element in the pathology of schizophrenia has emerged from a series of postmortem studies. How such abnormalities may contribute to the clinical features of schizophrenia has been substantially informed by a convergence with basic neuroscience studies revealing complex details of GABA neuron function in the healthy brain. Importantly, activity of the parvalbumin-containing class of GABA neurons has been linked to the production of cortical network oscillations. Furthermore, growing knowledge supports the concept that gamma band oscillations (30-80 Hz) are an essential mechanism for cortical information transmission and processing. Herein we review recent studies further indicating that inhibition from parvalbumin-positive GABA neurons is necessary to produce gamma oscillations in cortical circuits; provide an update on postmortem studies documenting that deficits in the expression of glutamic acid decarboxylase67, which accounts for most GABA synthesis in the cortex, are widely observed in schizophrenia; and describe studies using novel, noninvasive approaches directly assessing potential relations between alterations in GABA, oscillations, and cognitive function in schizophrenia.
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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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Abstract
Impaired cognitive functioning, including deficits in working memory, is considered to be a core and disabling feature of schizophrenia that is difficult to treat. Deficits in working memory in schizophrenia are attributable, at least in part, to specific pathological alterations in the neuronal circuitry of the dorsolateral prefrontal cortex that involve, but are not restricted to, disturbances in glutamate, GABA, and dopamine neurotransmission. Cannabis use provides an example of an environmental exposure that may have a deleterious impact on these neurotransmitter systems and thereby contribute to worsening of cognitive functioning in schizophrenia. Increasing knowledge of the nature of the molecular alterations in these cortical circuits may lead to the development of new pathophysiologically informed treatment options for cognitive deficits in schizophrenia.
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Affiliation(s)
- David W Volk
- Department of Psychiatry, University of Pittsburgh, 3811 O'Hara Street, BST W1653, Pittsburgh, PA 15213, USA.
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