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Saberi A, Wischnewski KJ, Jung K, Lotter LD, Schaare HL, Banaschewski T, Barker GJ, Bokde ALW, Desrivières S, Flor H, Grigis A, Garavan H, Gowland P, Heinz A, Brühl R, Martinot JL, Martinot MLP, Artiges E, Nees F, Orfanos DP, Lemaitre H, Poustka L, Hohmann S, Holz N, Baeuchl C, Smolka MN, Vaidya N, Walter H, Whelan R, Schumann G, Paus T, Dukart J, Bernhardt BC, Popovych OV, Eickhoff SB, Valk SL. Adolescent maturation of cortical excitation-inhibition balance based on individualized biophysical network modeling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.18.599509. [PMID: 38948771 PMCID: PMC11213014 DOI: 10.1101/2024.06.18.599509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
The balance of excitation and inhibition is a key functional property of cortical microcircuits which changes through the lifespan. Adolescence is considered a crucial period for the maturation of excitation-inhibition balance. This has been primarily observed in animal studies, yet human in vivo evidence on adolescent maturation of the excitation-inhibition balance at the individual level is limited. Here, we developed an individualized in vivo marker of regional excitation-inhibition balance in human adolescents, estimated using large-scale simulations of biophysical network models fitted to resting-state functional magnetic resonance imaging data from two independent cross-sectional (N = 752) and longitudinal (N = 149) cohorts. We found a widespread relative increase of inhibition in association cortices paralleled by a relative age-related increase of excitation, or lack of change, in sensorimotor areas across both datasets. This developmental pattern co-aligned with multiscale markers of sensorimotor-association differentiation. The spatial pattern of excitation-inhibition development in adolescence was robust to inter-individual variability of structural connectomes and modeling configurations. Notably, we found that alternative simulation-based markers of excitation-inhibition balance show a variable sensitivity to maturational change. Taken together, our study highlights an increase of inhibition during adolescence in association areas using cross sectional and longitudinal data, and provides a robust computational framework to estimate microcircuit maturation in vivo at the individual level.
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Affiliation(s)
- Amin Saberi
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Otto Hahn Group Cognitive Neurogenetics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Kevin J Wischnewski
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Mathematics, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Dusseldorf, Germany
| | - Kyesam Jung
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Leon D Lotter
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Max Planck School of Cognition, Stephanstrasse 1A, 04103 Leipzig, Germany
| | - H Lina Schaare
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Otto Hahn Group Cognitive Neurogenetics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Tobias Banaschewski
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, 68159 Mannheim, Germany
| | - Gareth J Barker
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom
| | - Arun L W Bokde
- Discipline of Psychiatry, School of Medicine and Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Sylvane Desrivières
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, United Kingdom
| | - Herta Flor
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, Mannheim, Germany
- Department of Psychology, School of Social Sciences, University of Mannheim, 68131 Mannheim, Germany
| | - Antoine Grigis
- NeuroSpin, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Hugh Garavan
- Departments of Psychiatry and Psychology, University of Vermont, 05405 Burlington, Vermont, USA
| | - Penny Gowland
- Sir Peter Mansfield Imaging Centre School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, United Kingdom
| | - Andreas Heinz
- Department of Psychiatry and Psychotherapy CCM, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- German Center for Mental Health (DZPG), site Berlin-Potsdam, Germany
| | - Rüdiger Brühl
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany
| | - Jean-Luc Martinot
- Institut National de la Santé et de la Recherche Médicale, INSERM U A10 "Trajectoires développementales en psychiatrie"; Université Paris-Saclay, Ecole Normale supérieure Paris-Saclay, CNRS, Centre Borelli; Gif-sur-Yvette, France
| | - Marie-Laure Paillère Martinot
- Institut National de la Santé et de la Recherche Médicale, INSERM U A10 "Trajectoires développementales en psychiatrie"; Université Paris-Saclay, Ecole Normale supérieure Paris-Saclay, CNRS, Centre Borelli; Gif-sur-Yvette, France
- AP-HP. Sorbonne Université, Department of Child and Adolescent Psychiatry, Pitié-Salpêtrière Hospital, Paris, France
| | - Eric Artiges
- Institut National de la Santé et de la Recherche Médicale, INSERM U A10 "Trajectoires développementales en psychiatrie"; Université Paris-Saclay, Ecole Normale supérieure Paris-Saclay, CNRS, Centre Borelli; Gif-sur-Yvette, France
- Psychiatry Department, EPS Barthélémy Durand, Etampes, France
| | - Frauke Nees
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, 68159 Mannheim, Germany
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, Mannheim, Germany
- Institute of Medical Psychology and Medical Sociology, University Medical Center Schleswig-Holstein, Kiel University, Kiel, Germany
| | | | - Herve Lemaitre
- NeuroSpin, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
- Institut des Maladies Neurodégénératives, UMR 5293, CNRS, CEA, Université de Bordeaux, 33076 Bordeaux, France
| | - Luise Poustka
- Department of Child and Adolescent Psychiatry, Center for Psychosocial Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Sarah Hohmann
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, 68159 Mannheim, Germany
| | - Nathalie Holz
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Square J5, 68159 Mannheim, Germany
| | - Christian Baeuchl
- Department of Psychiatry and Psychotherapy, Technische Universität Dresden, Dresden, Germany
| | - Michael N Smolka
- Department of Psychiatry and Psychotherapy, Technische Universität Dresden, Dresden, Germany
| | - Nilakshi Vaidya
- Centre for Population Neuroscience and Stratified Medicine (PONS), Department of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Germany
| | - Henrik Walter
- Department of Psychiatry and Psychotherapy CCM, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Robert Whelan
- School of Psychology and Global Brain Health Institute, Trinity College Dublin, Ireland
| | - Gunter Schumann
- Centre for Population Neuroscience and Stratified Medicine (PONS), Department of Psychiatry and Psychotherapy, Charité Universitätsmedizin Berlin, Germany
- Centre for Population Neuroscience and Precision Medicine (PONS), Institute for Science and Technology of Brain-inspired Intelligence (ISTBI), Fudan University, Shanghai, China
| | - Tomáš Paus
- Departments of Psychiatry and Neuroscience, Faculty of Medicine and Centre Hospitalier Universitaire Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
| | - Juergen Dukart
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Boris C Bernhardt
- Multimodal Imaging and Connectome Analysis Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada
| | - Oleksandr V Popovych
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Simon B Eickhoff
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sofie L Valk
- Institute of Neuroscience and Medicine - Brain and Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Otto Hahn Group Cognitive Neurogenetics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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Zizzo MG, Cicio A, Raimondo S, Alessandro R, Serio R. Age-related differences of γ-aminobutyric acid (GABA)ergic transmission in human colonic smooth muscle. Neurogastroenterol Motil 2022; 34:e14248. [PMID: 34432349 PMCID: PMC9285353 DOI: 10.1111/nmo.14248] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 07/10/2021] [Accepted: 08/10/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Enteric neurons undergo to functional changes during aging. We investigated the possible age-associated differences in enteric γ-aminobutyric acid (GABA)ergic transmission evaluating function and distribution of GABAergic receptors in human colon. METHODS Mechanical responses to GABA and GABA receptor agonists on slow phasic contractions were examined in vitro as changes in isometric tension in colonic muscle strips from young (<65 years old) and aged patients (>65 years old). GABAergic receptor expression was assessed by quantitative RT-PCR. KEY RESULTS In both preparations GABA induced an excitatory effect, consisting in an increase in the basal tone, antagonized by the GABAA receptor antagonist, bicuculline, and potentiated by phaclofen, GABAB receptor antagonist.Tetrodotoxin (TTX) and atropine-sensitive contractile responses to GABA and GABAA receptor agonist, muscimol, were more pronounced in old compared to young subjects. Baclofen, GABAB receptor agonist, induced a TTX-sensitive reduction of the amplitude of the spontaneous. Nω-nitro-l-arginine methyl ester (L-NAME), nitric oxide (NO) synthase inhibitor abolished the inhibitory responses in old preparations, but a residual responses persisted in young preparations, which in turn was abolished by suramin, purinergic receptor antagonist. α3-GABAA receptor subunit expression tends to change in an age-dependent manner. CONCLUSIONS AND INFERENCES Our results reveal age-related differences in GABAergic transmission in human colon. At all the age tested GABA regulates muscular contractility modulating the activity of the intrinsic neurons. Activation of GABAA receptor, through acetylcholine release, induces contraction, which increases in amplitude with age. GABAB receptor activation leads to neural release of NO and purines, being a loss of purinergic-component in aged group.
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Affiliation(s)
- Maria Grazia Zizzo
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF)University of PalermoViale delle Scienze,ed 16Palermo90128Italy,ATeN (Advanced Technologies Network) CenterUniversity of PalermoViale delle Scienze, ed 18Palermo90128Italy
| | - Adele Cicio
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF)University of PalermoViale delle Scienze,ed 16Palermo90128Italy
| | - Stefania Raimondo
- Department of Biomedicine, Neurosciences and Advanced Diagnostics (Bi.N.D)University of PalermoSection of Biology and GeneticsPalermo90133Italy
| | - Riccardo Alessandro
- Department of Biomedicine, Neurosciences and Advanced Diagnostics (Bi.N.D)University of PalermoSection of Biology and GeneticsPalermo90133Italy
| | - Rosa Serio
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF)University of PalermoViale delle Scienze,ed 16Palermo90128Italy
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Guerra A, Rocchi L, Grego A, Berardi F, Luisi C, Ferreri F. Contribution of TMS and TMS-EEG to the Understanding of Mechanisms Underlying Physiological Brain Aging. Brain Sci 2021; 11:405. [PMID: 33810206 PMCID: PMC8004753 DOI: 10.3390/brainsci11030405] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 12/21/2022] Open
Abstract
In the human brain, aging is characterized by progressive neuronal loss, leading to disruption of synapses and to a degree of failure in neurotransmission. However, there is increasing evidence to support the notion that the aged brain has a remarkable ability to reorganize itself, with the aim of preserving its physiological activity. It is important to develop objective markers able to characterize the biological processes underlying brain aging in the intact human, and to distinguish them from brain degeneration associated with many neurological diseases. Transcranial magnetic stimulation (TMS), coupled with electromyography or electroencephalography (EEG), is particularly suited to this aim, due to the functional nature of the information provided, and thanks to the ease with which it can be integrated with behavioral manipulation. In this review, we aimed to provide up to date information about the role of TMS and TMS-EEG in the investigation of brain aging. In particular, we focused on data about cortical excitability, connectivity and plasticity, obtained by using readouts such as motor evoked potentials and transcranial evoked potentials. Overall, findings in the literature support an important potential contribution of TMS to the understanding of the mechanisms underlying normal brain aging. Further studies are needed to expand the current body of information and to assess the applicability of TMS findings in the clinical setting.
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Affiliation(s)
| | - Lorenzo Rocchi
- Department of Clinical and Movements Neurosciences, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK;
- Department of Medical Sciences and Public Health, University of Cagliari, 09124 Cagliari, Italy
| | - Alberto Grego
- Department of Neuroscience, University of Padua, 35122 Padua, Italy; (A.G.); (F.B.); (C.L.)
| | - Francesca Berardi
- Department of Neuroscience, University of Padua, 35122 Padua, Italy; (A.G.); (F.B.); (C.L.)
| | - Concetta Luisi
- Department of Neuroscience, University of Padua, 35122 Padua, Italy; (A.G.); (F.B.); (C.L.)
| | - Florinda Ferreri
- Department of Neuroscience, University of Padua, 35122 Padua, Italy; (A.G.); (F.B.); (C.L.)
- Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, 70210 Kuopio, Finland
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Giangreco NP, Elias JE, Tatonetti NP. No population left behind: Improving paediatric drug safety using informatics and systems biology. Br J Clin Pharmacol 2020; 88:1464-1470. [PMID: 33332641 PMCID: PMC8209126 DOI: 10.1111/bcp.14705] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 10/26/2020] [Accepted: 12/05/2020] [Indexed: 12/12/2022] Open
Abstract
Adverse drugs effects (ADEs) in children are common and may result in disability and death. The current paediatric drug safety landscape, including clinical trials, is limited as it rarely includes children and relies on extrapolation from adults. Children are not small adults but go through an evolutionarily conserved and physiologically dynamic process of growth and maturation. Novel quantitative approaches, integrating observations from clinical trials and drug safety databases with dynamic mechanisms, can be used to systematically identify ADEs unique to childhood. In this perspective, we discuss three critical research directions using systems biology methodologies and novel informatics to improve paediatric drug safety, namely child versus adult drug safety profiles, age-dependent drug toxicities and genetic susceptibility of ADEs across childhood. We argue that a data-driven framework that leverages observational data, biomedical knowledge and systems biology modelling will reveal previously unknown mechanisms of pediatric adverse drug events and lead to improved paediatric drug safety.
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Affiliation(s)
- Nicholas P Giangreco
- Department of Biomedical Informatics and Systems Biology, Columbia University, New York, NY, USA
| | - Jonathan E Elias
- Department of Pediatrics, Instructor in Pediatrics, Assistant Medical Director of Information Services, Weill Cornell Medical & NYP Weill Cornell Medical Center, New York, NY, USA
| | - Nicholas P Tatonetti
- Department of Biomedical Informatics and Systems Biology, Columbia University, New York, NY, USA
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5
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Goetjen A, Watson M, Lieberman R, Clinton K, Kranzler HR, Covault J. Induced pluripotent stem cell reprogramming-associated methylation at the GABRA2 promoter and chr4p12 GABA A subunit gene expression in the context of alcohol use disorder. Am J Med Genet B Neuropsychiatr Genet 2020; 183:464-474. [PMID: 33029895 PMCID: PMC8022112 DOI: 10.1002/ajmg.b.32824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/27/2020] [Accepted: 09/15/2020] [Indexed: 11/07/2022]
Abstract
Twin studies indicate that there is a significant genetic contribution to the risk of developing alcohol use disorder (AUD). With the exception of coding variants in ADH1B and ALDH2, little is known about the molecular effects of AUD-associated loci. We previously reported that the AUD-associated synonymous polymorphism rs279858 within the GABAA α2 receptor subunit gene, GABRA2, was associated with gene expression of the chr4p12 GABAA subunit gene cluster in induced pluripotent stem cell (iPSC)-derived neural cultures. Based on this and other studies that showed changes in GABRA2 DNA methylation associated with schizophrenia and aging, we examined methylation in GABRA2. Specifically, using 69 iPSC lines and neural cultures derived from 47 of them, we examined whether GABRA2 rs279858 genotype predicted methylation levels and whether methylation was related to GABAA receptor subunit gene expression. We found that the GABRA2 CpG island undergoes random stochastic methylation during reprogramming and that methylation is associated with decreased GABRA2 gene expression, an effect that extends to the GABRB1 gene over 600 kb distal to GABRA2. Further, we identified additive effects of GABRA2 CpG methylation and GABRA2 rs279858 genotype on expression of the GABRB1 subunit gene in iPSC-derived neural cultures.
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Affiliation(s)
- Alexandra Goetjen
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut
- Genetics and Developmental Biology Graduate Program, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Maegan Watson
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Richard Lieberman
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Kaitlin Clinton
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Henry R. Kranzler
- Center for Studies of Addiction, Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania
- VISN 4 MIRECC, Crescenz VAMC, Philadelphia, Pennsylvania
| | - Jonathan Covault
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut
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Age-related GABAergic differences in the primary sensorimotor cortex: A multimodal approach combining PET, MRS and TMS. Neuroimage 2020; 226:117536. [PMID: 33186716 PMCID: PMC7894275 DOI: 10.1016/j.neuroimage.2020.117536] [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: 05/24/2020] [Revised: 10/10/2020] [Accepted: 10/28/2020] [Indexed: 01/15/2023] Open
Abstract
Healthy aging is associated with mechanistic changes in gamma-aminobutyric acid (GABA), the most abundant inhibitory neurotransmitter in the human brain. While previous work mainly focused on magnetic resonance spectroscopy (MRS)-based GABA+ levels and transcranial magnetic stimulation (TMS)-based GABAA receptor (GABAAR) activity in the primary sensorimotor (SM1) cortex, the aim of the current study was to identify age-related differences in positron emission tomography (PET)-based GABAAR availability and its relationship with GABA+ levels (i.e. GABA with the contribution of macromolecules) and GABAAR activity. For this purpose, fifteen young (aged 20–28 years) and fifteen older (aged 65–80 years) participants were recruited. PET and MRS images were acquired using simultaneous time-of-flight PET/MR to evaluate age-related differences in GABAAR availability (distribution volume ratio with pons as reference region) and GABA+ levels. TMS was applied to identify age-related differences in GABAAR activity by measuring short-interval intracortical inhibition (SICI). Whereas GABAAR availability was significantly higher in the SM cortex of older as compared to young adults (18.5%), there were neither age-related differences in GABA+ levels nor SICI. A correlation analysis revealed no significant associations between GABAAR availability, GABAAR activity and GABA+ levels. Although the exact mechanisms need to be further elucidated, it is possible that a higher GABAAR availability in older adults is a compensatory mechanism to ensure optimal inhibitory functionality during the aging process.
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Määttä S, Säisänen L, Kallioniemi E, Lakka TA, Lintu N, Haapala EA, Koskenkorva P, Niskanen E, Ferreri F, Könönen M. Maturation changes the excitability and effective connectivity of the frontal lobe: A developmental TMS-EEG study. Hum Brain Mapp 2019; 40:2320-2335. [PMID: 30648321 DOI: 10.1002/hbm.24525] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 12/07/2018] [Accepted: 01/07/2019] [Indexed: 12/22/2022] Open
Abstract
The combination of transcranial magnetic stimulation with simultaneous electroencephalography (TMS-EEG) offers direct neurophysiological insight into excitability and connectivity within neural circuits. However, there have been few developmental TMS-EEG studies to date, and they all have focused on primary motor cortex stimulation. In the present study, we used navigated high-density TMS-EEG to investigate the maturation of the superior frontal cortex (dorsal premotor cortex [PMd]), which is involved in a broad range of motor and cognitive functions known to develop with age. We demonstrated that reactivity to frontal cortex TMS decreases with development. We also showed that although frontal cortex TMS elicits an equally complex TEP waveform in all age groups, the statistically significant between-group differences in the topography of the TMS-evoked peaks and differences in current density maps suggest changes in effective connectivity of the right PMd with maturation. More generally, our results indicate that direct study of the brain's excitability and effective connectivity via TMS-EEG co-registration can also be applied to pediatric populations outside the primary motor cortex, and may provide useful information for developmental studies and studies on developmental neuropsychiatric disorders.
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Affiliation(s)
- Sara Määttä
- Faculty of Health Sciences, Department of Clinical Neurophysiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio Campus, Finland.,Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland
| | - Laura Säisänen
- Faculty of Health Sciences, Department of Clinical Neurophysiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio Campus, Finland.,Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland
| | - Elisa Kallioniemi
- Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas
| | - Timo A Lakka
- Faculty of Health Sciences, Institute of Biomedicine, University of Eastern Finland, Kuopio Campus, Finland.,Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland.,Foundation for Research in Health Exercise and Nutrition, Kuopio Research Institute of Exercise Medicine, Kuopio, Finland
| | - Niina Lintu
- Faculty of Health Sciences, Institute of Biomedicine, University of Eastern Finland, Kuopio Campus, Finland
| | - Eero A Haapala
- Faculty of Health Sciences, Institute of Biomedicine, University of Eastern Finland, Kuopio Campus, Finland.,Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Päivi Koskenkorva
- Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland
| | - Eini Niskanen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
| | - Florinda Ferreri
- Department of Neuroscience, Unit of Neurology and Neurophysiology, University of Padua, Padua, Italy
| | - Mervi Könönen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.,Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland
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Russell MA, Schlomer GL, Cleveland HH, Feinberg ME, Greenberg MT, Spoth RL, Redmond C, Vandenbergh DJ. PROSPER Intervention Effects on Adolescents' Alcohol Misuse Vary by GABRA2 Genotype and Age. PREVENTION SCIENCE : THE OFFICIAL JOURNAL OF THE SOCIETY FOR PREVENTION RESEARCH 2019; 19:27-37. [PMID: 28185103 DOI: 10.1007/s11121-017-0751-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Preventive intervention effects on adolescent alcohol misuse may differ based on genotypes in gene-by-intervention (G x I) interactions, and these G x I interactions may vary as a function of age. The current study uses a novel statistical method, time-varying effect modeling (TVEM), to test an age-varying interaction between a single nucleotide polymorphism in the GABRA2 gene (rs279845) and a preventive intervention in predicting alcohol misuse in a longitudinal study of adolescents (ages 11-20). The preventive intervention was PROSPER, a community-based system for delivery of family and school programs selected from a menu of evidence-based interventions. TVEM results revealed a significant age-varying GABRA2 x intervention interaction from ages 12 to 18, with the peak effect size seen around age 13 (IRR = 0.50). The intervention significantly reduced alcohol misuse for adolescents with the GABRA2 TT genotype from ages 12.5 to 17 but did not reduce alcohol use for adolescents with the GABRA2 A allele at any age. Differences in intervention effects by GABRA2 genotype were most pronounced from ages 13 to 16-a period when drinking is associated with increased risk for alcohol use disorder. Our findings provide additional evidence that intervention effects on adolescent alcohol misuse may differ by genotype, and provide novel evidence that the interaction between GABRA2 and intervention effects on alcohol use may vary with age. Implications for interventions targeting adolescent alcohol misuse are discussed.
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Affiliation(s)
- Michael A Russell
- The Pennsylvania State University, 404 Health and Human Development Building, University Park, PA, 16802, USA.
| | | | | | - Mark E Feinberg
- The Pennsylvania State University, University Park, PA, 16802, USA
| | - Mark T Greenberg
- The Pennsylvania State University, University Park, PA, 16802, USA
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Pandya M, Palpagama TH, Turner C, Waldvogel HJ, Faull RL, Kwakowsky A. Sex- and age-related changes in GABA signaling components in the human cortex. Biol Sex Differ 2019; 10:5. [PMID: 30642393 PMCID: PMC6332906 DOI: 10.1186/s13293-018-0214-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/09/2018] [Indexed: 12/13/2022] Open
Abstract
Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the nervous system. Previous studies have shown fluctuations in expression levels of GABA signaling components-glutamic acid decarboxylase (GAD), GABA receptor (GABAR) subunit, and GABA transporter (GAT)-with increasing age and between sexes; however, this limited knowledge is highly based on animal models that produce inconsistent findings. This study is the first analysis of the age- and sex-specific changes of the GAD, GABAA/BR subunits, and GAT expression in the human primary sensory and motor cortices; superior (STG), middle (MTG), and inferior temporal gyrus (ITG); and cerebellum. Utilizing Western blotting, we found that the GABAergic system is relatively robust against sex and age-related differences in all brain regions examined. However, we observed several sex-dependent differences in GABAAR subunit expression in STG along with age-dependent GABAAR subunit and GAD level alteration. No significant age-related differences were found in α1, α2, α5, β3, and γ2 subunit expression in the STG. However, we found significantly higher GABAAR α3 subunit expression in the STG in young males compared to old males. We observed a significant sex-dependent difference in α1 subunit expression: males presenting significantly higher levels compared to women across all stages of life in STG. Older females showed significantly lower α2, α5, and β3 subunit expression compared to old males in the STG. These changes found in the STG might significantly influence GABAergic neurotransmission and lead to sex- and age-specific disease susceptibility and progression.
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Affiliation(s)
- Madhavi Pandya
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Thulani H. Palpagama
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
- Department of Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Henry J. Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L. Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Olsen RW, Liang J. Role of GABA A receptors in alcohol use disorders suggested by chronic intermittent ethanol (CIE) rodent model. Mol Brain 2017; 10:45. [PMID: 28931433 PMCID: PMC5605989 DOI: 10.1186/s13041-017-0325-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/05/2017] [Indexed: 11/10/2022] Open
Abstract
GABAergic inhibitory transmission is involved in the acute and chronic effects of ethanol on the brain and behavior. One-dose ethanol exposure induces transient plastic changes in GABAA receptor subunit levels, composition, and regional and subcellular localization. Rapid down-regulation of early responder δ subunit-containing GABAA receptor subtypes mediating ethanol-sensitive tonic inhibitory currents in critical neuronal circuits corresponds to rapid tolerance to ethanol's behavioral responses. Slightly slower, α1 subunit-containing GABAA receptor subtypes mediating ethanol-insensitive synaptic inhibition are down-regulated, corresponding to tolerance to additional ethanol behaviors plus cross-tolerance to other GABAergic drugs including benzodiazepines, anesthetics, and neurosteroids, especially sedative-hypnotic effects. Compensatory up-regulation of synaptically localized α4 and α2 subunit-containing GABAA receptor subtypes, mediating ethanol-sensitive synaptic inhibitory currents follow, but exhibit altered physio-pharmacology, seizure susceptibility, hyperexcitability, anxiety, and tolerance to GABAergic positive allosteric modulators, corresponding to heightened alcohol withdrawal syndrome. All these changes (behavioral, physiological, and biochemical) induced by ethanol administration are transient and return to normal in a few days. After chronic intermittent ethanol (CIE) treatment the same changes are observed but they become persistent after 30 or more doses, lasting for at least 120 days in the rat, and probably for life. We conclude that the ethanol-induced changes in GABAA receptors represent aberrant plasticity contributing critically to ethanol dependence and increased voluntary consumption. We suggest that the craving, drug-seeking, and increased consumption in the rat model are tied to ethanol-induced plastic changes in GABAA receptors, importantly the development of ethanol-sensitive synaptic GABAA receptor-mediating inhibitory currents that participate in maintained positive reward actions of ethanol on critical neuronal circuits. These probably disinhibit nerve endings of inhibitory GABAergic neurons on dopamine reward circuit cells, and limbic system circuits mediating anxiolysis in hippocampus and amygdala. We further suggest that the GABAA receptors contributing to alcohol dependence in the rat and presumably in human alcohol use disorders (AUD) are the ethanol-induced up-regulated subtypes containing α4 and most importantly α2 subunits. These mediate critical aspects of the positive reinforcement of ethanol in the dependent chronic user while alleviating heightened withdrawal symptoms experienced whenever ethanol is absent. The speculative conclusions based on firm observations are readily testable.
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Affiliation(s)
- Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| | - Jing Liang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90089 USA
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11
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Ferreri F, Guerra A, Vollero L, Ponzo D, Maatta S, Mervaala E, Iannello G, Di Lazzaro V. Age-related changes of cortical excitability and connectivity in healthy humans: non-invasive evaluation of sensorimotor network by means of TMS-EEG. Neuroscience 2017. [DOI: 10.1016/j.neuroscience.2017.06.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Florinda Ferreri
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, University Campus Bio-Medico, via Álvaro del Portillo 21, 00128 Rome, Italy; Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, 70029 KYS, Kuopio, Finland.
| | - Andrea Guerra
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, University Campus Bio-Medico, via Álvaro del Portillo 21, 00128 Rome, Italy
| | - Luca Vollero
- Department of Computer Science and Computer Engineering, University Campus Bio-Medico, via Álvaro del Portillo 200, 00128 Rome, Italy
| | - David Ponzo
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, University Campus Bio-Medico, via Álvaro del Portillo 21, 00128 Rome, Italy
| | - Sara Maatta
- Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, 70029 KYS, Kuopio, Finland
| | - Esa Mervaala
- Department of Clinical Neurophysiology, Kuopio University Hospital, University of Eastern Finland, 70029 KYS, Kuopio, Finland
| | - Giulio Iannello
- Department of Computer Science and Computer Engineering, University Campus Bio-Medico, via Álvaro del Portillo 200, 00128 Rome, Italy
| | - Vincenzo Di Lazzaro
- Unit of Neurology, Neurophysiology, Neurobiology, Department of Medicine, University Campus Bio-Medico, via Álvaro del Portillo 21, 00128 Rome, Italy
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12
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Lindemeyer AK, Shen Y, Yazdani F, Shao XM, Spigelman I, Davies DL, Olsen RW, Liang J. α2 Subunit-Containing GABA A Receptor Subtypes Are Upregulated and Contribute to Alcohol-Induced Functional Plasticity in the Rat Hippocampus. Mol Pharmacol 2017; 92:101-112. [PMID: 28536106 DOI: 10.1124/mol.116.107797] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/05/2017] [Indexed: 12/20/2022] Open
Abstract
Alcohol (EtOH) intoxication causes changes in the rodent brain γ-aminobutyric acid receptor (GABAAR) subunit composition and function, playing a crucial role in EtOH withdrawal symptoms and dependence. Building evidence indicates that withdrawal from acute EtOH and chronic intermittent EtOH (CIE) results in decreased EtOH-enhanced GABAAR δ subunit-containing extrasynaptic and EtOH-insensitive α1βγ2 subtype synaptic GABAARs but increased synaptic α4βγ2 subtype, and increased EtOH sensitivity of GABAAR miniature postsynaptic currents (mIPSCs) correlated with EtOH dependence. Here we demonstrate that after acute EtOH intoxication and CIE, upregulation of hippocampal α4βγ2 subtypes, as well as increased cell-surface levels of GABAAR α2 and γ1 subunits, along with increased α2β1γ1 GABAAR pentamers in hippocampal slices using cell-surface cross-linking, followed by Western blot and coimmunoprecipitation. One-dose and two-dose acute EtOH treatments produced temporal plastic changes in EtOH-induced anxiolysis or withdrawal anxiety, and the presence or absence of EtOH-sensitive synaptic currents correlated with cell surface peptide levels of both α4 and γ1(new α2) subunits. CIE increased the abundance of novel mIPSC patterns differing in activation/deactivation kinetics, charge transfer, and sensitivity to EtOH. The different mIPSC patterns in CIE could be correlated with upregulated highly EtOH-sensitive α2βγ subtypes and EtOH-sensitive α4βγ2 subtypes. Naïve α4 subunit knockout mice express EtOH-sensitive mIPSCs in hippocampal slices, correlating with upregulated GABAAR α2 (and not α4) subunits. Consistent with α2, β1, and γ1 subunits genetically linked to alcoholism in humans, our findings indicate that these new α2-containing synaptic GABAARs could mediate the maintained anxiolytic response to EtOH in dependent individuals, rat or human, contributing to elevated EtOH consumption.
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Affiliation(s)
- A Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Yi Shen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Ferin Yazdani
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Xuesi M Shao
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Igor Spigelman
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Daryl L Davies
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Richard W Olsen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Jing Liang
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
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13
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Layer 3 Excitatory and Inhibitory Circuitry in the Prefrontal Cortex: Developmental Trajectories and Alterations in Schizophrenia. Biol Psychiatry 2017; 81:862-873. [PMID: 27455897 PMCID: PMC5136518 DOI: 10.1016/j.biopsych.2016.05.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 05/25/2016] [Accepted: 05/25/2016] [Indexed: 11/20/2022]
Abstract
Convergent evidence suggests that schizophrenia is a disorder of neurodevelopment with alterations in both early and late developmental processes hypothesized to contribute to the disease process. Abnormalities in certain clinical features of schizophrenia, such as working memory impairments, depend on distributed neural circuitry including the dorsolateral prefrontal cortex (DLPFC) and appear to arise during the protracted maturation of this circuitry across childhood and adolescence. In particular, the neural circuitry substrate for working memory in primates involves the coordinated activity of excitatory pyramidal neurons and a specific population of inhibitory gamma-aminobutyric acid neurons (i.e., parvalbumin-containing basket cells) in layer 3 of the DLPFC. Understanding the relationships between the normal development of-and the schizophrenia-associated alterations in-the DLPFC circuitry that subserves working memory could provide new insights into the nature of schizophrenia as a neurodevelopmental disorder. Consequently, we review the following in this article: 1) recent findings regarding alterations of DLPFC layer 3 circuitry in schizophrenia, 2) the developmental refinements in this circuitry that occur during the period when the working memory alterations in schizophrenia appear to arise and progress, and 3) how various adverse environmental exposures could contribute to developmental disturbances of this circuitry in individuals with schizophrenia.
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14
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Ion Channel Genes and Epilepsy: Functional Alteration, Pathogenic Potential, and Mechanism of Epilepsy. Neurosci Bull 2017; 33:455-477. [PMID: 28488083 DOI: 10.1007/s12264-017-0134-1] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 02/20/2017] [Indexed: 01/29/2023] Open
Abstract
Ion channels are crucial in the generation and modulation of excitability in the nervous system and have been implicated in human epilepsy. Forty-one epilepsy-associated ion channel genes and their mutations are systematically reviewed. In this paper, we analyzed the genotypes, functional alterations (funotypes), and phenotypes of these mutations. Eleven genes featured loss-of-function mutations and six had gain-of-function mutations. Nine genes displayed diversified funotypes, among which a distinct funotype-phenotype correlation was found in SCN1A. These data suggest that the funotype is an essential consideration in evaluating the pathogenicity of mutations and a distinct funotype or funotype-phenotype correlation helps to define the pathogenic potential of a gene.
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15
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Piekarski DJ, Johnson CM, Boivin JR, Thomas AW, Lin WC, Delevich K, M Galarce E, Wilbrecht L. Does puberty mark a transition in sensitive periods for plasticity in the associative neocortex? Brain Res 2017; 1654:123-144. [PMID: 27590721 PMCID: PMC5283387 DOI: 10.1016/j.brainres.2016.08.042] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 08/17/2016] [Accepted: 08/29/2016] [Indexed: 02/08/2023]
Abstract
Postnatal brain development is studded with sensitive periods during which experience dependent plasticity is enhanced. This enables rapid learning from environmental inputs and reorganization of cortical circuits that matches behavior with environmental contingencies. Significant headway has been achieved in characterizing and understanding sensitive period biology in primary sensory cortices, but relatively little is known about sensitive period biology in associative neocortex. One possible mediator is the onset of puberty, which marks the transition to adolescence, when animals shift their behavior toward gaining independence and exploring their social world. Puberty onset correlates with reduced behavioral plasticity in some domains and enhanced plasticity in others, and therefore may drive the transition from juvenile to adolescent brain function. Pubertal onset is also occurring earlier in developed nations, particularly in unserved populations, and earlier puberty is associated with vulnerability for substance use, depression and anxiety. In the present article we review the evidence that supports a causal role for puberty in developmental changes in the function and neurobiology of the associative neocortex. We also propose a model for how pubertal hormones may regulate sensitive period plasticity in associative neocortex. We conclude that the evidence suggests puberty onset may play a causal role in some aspects of associative neocortical development, but that further research that manipulates puberty and measures gonadal hormones is required. We argue that further work of this kind is urgently needed to determine how earlier puberty may negatively impact human health and learning potential. This article is part of a Special Issue entitled SI: Adolescent plasticity.
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Affiliation(s)
- David J Piekarski
- Department of Psychology, University of California, Berkeley, Berkeley CA 94720, USA
| | - Carolyn M Johnson
- Department of Psychology, University of California, Berkeley, Berkeley CA 94720, USA
| | - Josiah R Boivin
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco CA 94158, USA
| | - A Wren Thomas
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley CA 94720, USA
| | - Wan Chen Lin
- Department of Psychology, University of California, Berkeley, Berkeley CA 94720, USA
| | - Kristen Delevich
- Department of Psychology, University of California, Berkeley, Berkeley CA 94720, USA
| | - Ezequiel M Galarce
- School of Public Health, University of California, Berkeley, Berkeley CA 94720, USA
| | - Linda Wilbrecht
- Department of Psychology, University of California, Berkeley, Berkeley CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley CA 94720, USA.
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Immunochemical Localization of GABA A Receptor Subunits in the Freshwater Polyp Hydra vulgaris (Cnidaria, Hydrozoa). Neurochem Res 2016; 41:2914-2922. [PMID: 27450241 DOI: 10.1007/s11064-016-2010-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/14/2016] [Accepted: 07/16/2016] [Indexed: 10/21/2022]
Abstract
γ-aminobutyric acid (GABA) receptors, responding to GABA positive allosteric modulators, are present in the freshwater polyp Hydra vulgaris (Cnidaria, Hydrozoa), one of the most primitive metazoans to develop a nervous system. We examined the occurrence and distribution of GABAA receptor subunits in Hydra tissues by western blot and immunohistochemistry. Antibodies against different GABAA receptor subunits were used in Hydra membrane preparations. Unique protein bands, inhibited by the specific peptide, appeared at 35, 60, ∼50 and ∼52 kDa in membranes incubated with α3, β1, γ3 or δ antibodies, respectively. Immunohistochemical screening of whole mount Hydra preparations revealed diffuse immunoreactivity to α3, β1 or γ3 antibodies in tentacles, hypostome, and upper part of the gastric region; immunoreactive fibers were also present in the lower peduncle. By contrast, δ antibodies revealed a strong labeling in the lower gastric region and peduncle, as well as in tentacles. Double labeling showed colocalization of α3/β1, α3/γ3 and α3/δ immunoreactivity in granules or cells in tentacles and gastric region. In the peduncle, colocalization of both α3/β1 and α3/γ3 immunoreactivity was found in fibers running horizontally above the foot. These data indicate that specific GABAA receptor subunits are present and differentially distributed in Hydra body regions. Subunit colocalization suggests that Hydra GABA receptors are heterologous multimers, possibly sub-serving different physiological activities.
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17
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Developmental pharmacology of benzodiazepines under normal and pathological conditions. Epileptic Disord 2016; 16 Spec No 1:S59-68. [PMID: 25335485 DOI: 10.1684/epd.2014.0690] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Benzodiazepines are allosteric agonists of GABAA receptors (GABAAR), pentameric ligand-gated Cl(-) channels, which serve both an important neurodevelopmental role but are also the principal inhibitory system in the brain. However, their subunit composition, channel properties, and function, as well as their region-specific expression patterns, change through development. These processes have been extensively studied in rodents and to some extent confirmed in higher species. Specifically, GABAARs acquire faster kinetics with age and their pharmacology changes rendering them more sensitive to drugs that have higher affinity for α1 subunit-containing GABAARs, such as benzodiazepines, but also, their inhibitory function becomes more potent as they shift from having depolarising to hyperpolarising responses due to a shift in Cl(-) gradient and cation chloride cotransporter expression. Concerns have been raised about possible pro-apoptotic and paradoxical effects of benzodiazepines in the neonatal normal rat brain, although it is unclear, as yet, whether this extends to brains exposed to seizures. Growing evidence indicates that the pharmacology and physiology of GABAARs may be altered in the brain of rats or humans with seizures or epilepsy, or different aetiologies that predispose to epilepsy. These changes follow different paths, depending on sex, age, region, cell type, aetiology, or time-point specific factors. Identification of dynamic biomarkers that could enable these changes in vivo to be monitored would greatly facilitate the selection of more effective agonists with fewer side effects.
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Janve VS, Hernandez CC, Verdier KM, Hu N, Macdonald RL. Epileptic encephalopathy de novo GABRB mutations impair γ-aminobutyric acid type A receptor function. Ann Neurol 2016; 79:806-825. [PMID: 26950270 PMCID: PMC5014730 DOI: 10.1002/ana.24631] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 03/04/2016] [Accepted: 03/05/2016] [Indexed: 01/27/2023]
Abstract
OBJECTIVE The Epi4K Consortium recently identified 4 de novo mutations in the γ-aminobutyric acid type A (GABAA ) receptor β3 subunit gene GABRB3 and 1 in the β1 subunit gene GABRB1 in children with one of the epileptic encephalopathies (EEs) Lennox-Gastaut syndrome (LGS) and infantile spasms (IS). Because the etiology of EEs is often unknown, we determined the impact of GABRB mutations on GABAA receptor function and biogenesis. METHODS GABAA receptor α1 and γ2L subunits were coexpressed with wild-type and/or mutant β3 or β1 subunits in HEK 293T cells. Currents were measured using whole cell and single channel patch clamp techniques. Surface and total expression levels were measured using flow cytometry. Potential structural perturbations in mutant GABAA receptors were explored using structural modeling. RESULTS LGS-associated GABRB3(D120N, E180G, Y302C) mutations located at β+ subunit interfaces reduced whole cell currents by decreasing single channel open probability without loss of surface receptors. In contrast, IS-associated GABRB3(N110D) and GABRB1(F246S) mutations at β- subunit interfaces produced minor changes in whole cell current peak amplitude but altered current deactivation by decreasing or increasing single channel burst duration, respectively. GABRB3(E180G) and GABRB1(F246S) mutations also produced spontaneous channel openings. INTERPRETATION All 5 de novo GABRB mutations impaired GABAA receptor function by rearranging conserved structural domains, supporting their role in EEs. The primary effect of LGS-associated mutations was reduced GABA-evoked peak current amplitudes, whereas the major impact of IS-associated mutations was on current kinetic properties. Despite lack of association with epilepsy syndromes, our results suggest GABRB1 as a candidate human epilepsy gene. Ann Neurol 2016;79:806-825.
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Affiliation(s)
- Vaishali S Janve
- Graduate Program of Neuroscience, Vanderbilt University, Nashville, TN
| | | | | | - Ningning Hu
- Department of Neurology, Vanderbilt University, Nashville, TN
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Lieberman R, Kranzler HR, Joshi P, Shin DG, Covault J. GABRA2 Alcohol Dependence Risk Allele is Associated with Reduced Expression of Chromosome 4p12 GABAA Subunit Genes in Human Neural Cultures. Alcohol Clin Exp Res 2015; 39:1654-64. [PMID: 26250693 DOI: 10.1111/acer.12807] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 06/05/2015] [Indexed: 01/28/2023]
Abstract
BACKGROUND Genetic variation in a region of chromosome 4p12 that includes the GABAA subunit gene GABRA2 has been reproducibly associated with alcohol dependence (AD). However, the molecular mechanisms underlying the association are unknown. This study examined correlates of in vitro gene expression of the AD-associated GABRA2 rs279858*C-allele in human neural cells using an induced pluripotent stem cell (iPSC) model system. METHODS We examined mRNA expression of chromosome 4p12 GABAA subunit genes (GABRG1, GABRA2, GABRA4, and GABRB1) in 36 human neural cell lines differentiated from iPSCs using quantitative polymerase chain reaction and next-generation RNA sequencing. mRNA expression in adult human brain was examined using the BrainCloud and BRAINEAC data sets. RESULTS We found significantly lower levels of GABRA2 mRNA in neural cell cultures derived from rs279858*C-allele carriers. Levels of GABRA2 RNA were correlated with those of the other 3 chromosome 4p12 GABAA genes, but not other neural genes. Cluster analysis based on the relative RNA levels of the 4 chromosome 4p12 GABAA genes identified 2 distinct clusters of cell lines, a low-expression cluster associated with rs279858*C-allele carriers and a high-expression cluster enriched for the rs279858*T/T genotype. In contrast, there was no association of genotype with chromosome 4p12 GABAA gene expression in postmortem adult cortex in either the BrainCloud or BRAINEAC data sets. CONCLUSIONS AD-associated variation in GABRA2 is associated with differential expression of the entire cluster of GABAA subunit genes on chromosome 4p12 in human iPSC-derived neural cell cultures. The absence of a parallel effect in postmortem human adult brain samples suggests that AD-associated genotype effects on GABAA expression, although not present in mature cortex, could have effects on regulation of the chromosome 4p12 GABAA cluster during neural development.
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Affiliation(s)
- Richard Lieberman
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut.,Department of Neuroscience, University of Connecticut Health Center, University of Connecticut School of Medicine, Farmington, Connecticut
| | - Henry R Kranzler
- Center for Studies of Addiction, Department of Psychiatry, Perelman School of Medicine of the University of Pennsylvania, Philadelphia, Pennsylvania.,VISN4 MIRECC, Philadelphia VAMC, Philadelphia, Pennsylvania
| | - Pujan Joshi
- Department of Computer Science and Engineering, University of Connecticut, Storrs, Connecticut
| | - Dong-Guk Shin
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut.,Department of Computer Science and Engineering, University of Connecticut, Storrs, Connecticut
| | - Jonathan Covault
- Alcohol Research Center, Department of Psychiatry, University of Connecticut School of Medicine, Farmington, Connecticut.,Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut
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Hagihara H, Ohira K, Takao K, Miyakawa T. Transcriptomic evidence for immaturity of the prefrontal cortex in patients with schizophrenia. Mol Brain 2014; 7:41. [PMID: 24886351 PMCID: PMC4066280 DOI: 10.1186/1756-6606-7-41] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 05/20/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Schizophrenia, a severe psychiatric disorder, has a lifetime prevalence of 1%. The exact mechanisms underlying this disorder remain unknown, though theories abound. Recent studies suggest that particular cell types and biological processes in the schizophrenic cortex have a pseudo-immature status in which the molecular properties partially resemble those in the normal immature brain. However, genome-wide gene expression patterns in the brains of patients with schizophrenia and those of normal infants have not been directly compared. Here, we show that the gene expression patterns in the schizophrenic prefrontal cortex (PFC) resemble those in the juvenile PFC. RESULTS We conducted a gene expression meta-analysis in which, using microarray data derived from different studies, altered expression patterns in the dorsolateral PFC (DLFC) of patients with schizophrenia were compared with those in the DLFC of developing normal human brains, revealing a striking similarity. The results were replicated in a second DLFC data set and a medial PFC (MFC) data set. We also found that about half of the genes representing the transcriptomic immaturity of the schizophrenic PFC were developmentally regulated in fast-spiking interneurons, astrocytes, and oligodendrocytes. Furthermore, to test whether medications, which often confound the results of postmortem analyses, affect on the juvenile-like gene expressions in the schizophrenic PFC, we compared the gene expression patterns showing transcriptomic immaturity in the schizophrenic PFC with those in the PFC of rodents treated with antipsychotic drugs. The results showed no apparent similarities between the two conditions, suggesting that the juvenile-like gene expression patterns observed in the schizophrenic PFC could not be accounted for by medication effects. Moreover, the developing human PFC showed a gene expression pattern similar to that of the PFC of naive Schnurri-2 knockout mice, an animal model of schizophrenia with good face and construct validity. This result also supports the idea that the transcriptomic immaturity of the schizophrenic PFC is not due to medication effects. CONCLUSIONS Collectively, our results provide evidence that pseudo-immaturity of the PFC resembling juvenile PFC may be an endophenotype of schizophrenia.
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Affiliation(s)
- Hideo Hagihara
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
- CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Koji Ohira
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
- CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Keizo Takao
- CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
- Section of Behavior Patterns, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, 38 Aza-Nishigo-naka, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan
| | - Tsuyoshi Miyakawa
- Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
- CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
- Section of Behavior Patterns, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, 38 Aza-Nishigo-naka, Myodaiji-cho, Okazaki, Aichi 444-8787, Japan
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Fritschy JM, Panzanelli P. GABAAreceptors and plasticity of inhibitory neurotransmission in the central nervous system. Eur J Neurosci 2014; 39:1845-65. [DOI: 10.1111/ejn.12534] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and ETH; Zurich Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini; University of Turin; Turin Italy
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Beveridge NJ, Santarelli DM, Wang X, Tooney PA, Webster MJ, Weickert CS, Cairns MJ. Maturation of the human dorsolateral prefrontal cortex coincides with a dynamic shift in microRNA expression. Schizophr Bull 2014; 40:399-409. [PMID: 23378013 PMCID: PMC3932079 DOI: 10.1093/schbul/sbs198] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
MicroRNA are small RNAs that provide specificity for the RNA induced silencing complex, which forms the basis of an exquisite combinatorial system for posttranscriptional regulation. This system, essential for complex metazoans, is exemplified in the development of the cerebral cortex. To explore the complexity of human cortical miRNA expression in detail, we analyzed RNA from postmortem prefrontal cortex from 97 subjects aged 2 months to 78 years using miRNA microarray. Global miRNA expression was highest in the early years before declining significantly after adolescence (n = 140 decreased, n = 32 increased). Late adolescence was also marked by an inflection point between miRNA on an upward trajectory vs the majority going down. Functional annotation of target genes displaying inverse mRNA expression patterns in the same tissue were overrepresented in neurodevelopmentally significant pathways including neurological disease (most significantly schizophrenia), nervous system development, and cell-to-cell signaling. As mature miRNA expression is largely posttranscriptionally regulated, miRNA biogenesis gene expression was also examined. Dicer and Exportin-5 displayed significant associations with age; however, neither correlated with global miRNA expression across the lifespan. This investigation of cortical miRNA expression provides a framework for understanding the complex posttranscriptional regulatory environment during development and aging that may form a substrate for changes observed in neurodevelopmental disorders.
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Affiliation(s)
- Natalie J Beveridge
- To whom correspondence should be addressed; School of Biomedical Sciences & Pharmacy, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; tel: +61-2-4921-8670, fax: +61-2-4921-7903, e-mail:
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23
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Catts VS, Fung SJ, Long LE, Joshi D, Vercammen A, Allen KM, Fillman SG, Rothmond DA, Sinclair D, Tiwari Y, Tsai SY, Weickert TW, Shannon Weickert C. Rethinking schizophrenia in the context of normal neurodevelopment. Front Cell Neurosci 2013; 7:60. [PMID: 23720610 PMCID: PMC3654207 DOI: 10.3389/fncel.2013.00060] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/16/2013] [Indexed: 01/11/2023] Open
Abstract
The schizophrenia brain is differentiated from the normal brain by subtle changes, with significant overlap in measures between normal and disease states. For the past 25 years, schizophrenia has increasingly been considered a neurodevelopmental disorder. This frame of reference challenges biological researchers to consider how pathological changes identified in adult brain tissue can be accounted for by aberrant developmental processes occurring during fetal, childhood, or adolescent periods. To place schizophrenia neuropathology in a neurodevelopmental context requires solid, scrutinized evidence of changes occurring during normal development of the human brain, particularly in the cortex; however, too often data on normative developmental change are selectively referenced. This paper focuses on the development of the prefrontal cortex and charts major molecular, cellular, and behavioral events on a similar time line. We first consider the time at which human cognitive abilities such as selective attention, working memory, and inhibitory control mature, emphasizing that attainment of full adult potential is a process requiring decades. We review the timing of neurogenesis, neuronal migration, white matter changes (myelination), and synapse development. We consider how molecular changes in neurotransmitter signaling pathways are altered throughout life and how they may be concomitant with cellular and cognitive changes. We end with a consideration of how the response to drugs of abuse changes with age. We conclude that the concepts around the timing of cortical neuronal migration, interneuron maturation, and synaptic regression in humans may need revision and include greater emphasis on the protracted and dynamic changes occurring in adolescence. Updating our current understanding of post-natal neurodevelopment should aid researchers in interpreting gray matter changes and derailed neurodevelopmental processes that could underlie emergence of psychosis.
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Affiliation(s)
- Vibeke S. Catts
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Samantha J. Fung
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Leonora E. Long
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia
| | - Dipesh Joshi
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Ans Vercammen
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
- School of Psychology, Australian Catholic UniversitySydney, NSW, Australia
| | - Katherine M. Allen
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Stu G. Fillman
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Debora A. Rothmond
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
| | - Duncan Sinclair
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Yash Tiwari
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Medical Sciences, University of New South WalesSydney, NSW, Australia
| | - Shan-Yuan Tsai
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Thomas W. Weickert
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Laboratory, Schizophrenia Research InstituteSydney, NSW, Australia
- Neuroscience Research AustraliaSydney, NSW, Australia
- School of Psychiatry, University of New South WalesSydney, NSW, Australia
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Verdurand M, Fillman SG, Shannon Weickert C, Zavitsanou K. Increases in [3H]muscimol and [3H]flumazenil binding in the dorsolateral prefrontal cortex in schizophrenia are linked to α4 and γ2S mRNA levels respectively. PLoS One 2013; 8:e52724. [PMID: 23320076 PMCID: PMC3540049 DOI: 10.1371/journal.pone.0052724] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 11/21/2012] [Indexed: 11/30/2022] Open
Abstract
Background GABAA receptors (GABAAR) are composed of several subunits that determine sensitivity to drugs, synaptic localisation and function. Recent studies suggest that agonists targeting selective GABAAR subunits may have therapeutic value against the cognitive impairments observed in schizophrenia. In this study, we determined whether GABAAR binding deficits exist in the dorsolateral prefrontal cortex (DLPFC) of people with schizophrenia and tested if changes in GABAAR binding are related to the changes in subunit mRNAs. The GABA orthosteric and the benzodiazepine allosteric binding sites were assessed autoradiographically using [3H]Muscimol and [3H]Flumazenil, respectively, in a large cohort of individuals with schizophrenia (n = 37) and their matched controls (n = 37). We measured, using qPCR, mRNA of β (β1, β2, β3), γ (γ1, γ2, γ2S for short and γ2L for long isoform, γ3) and δ subunits and used our previous measurements of GABAAR α subunit mRNAs in order to relate mRNAs and binding through correlation and regression analysis. Results Significant increases in both [3H]Muscimol (p = 0.016) and [3H]Flumazenil (p = 0.012) binding were found in the DLPFC of schizophrenia patients. Expression levels of mRNA subunits measured did not show any significant difference in schizophrenia compared to controls. Regression analysis revealed that in schizophrenia, the [3H]Muscimol binding variance was most related to α4 mRNA levels and the [3H]Flumazenil binding variance was most related to γ2S subunit mRNA levels. [3H]Muscimol and [3H]Flumazenil binding were not affected by the lifetime anti-psychotics dose (chlorpromazine equivalent). Conclusions We report parallel increases in orthosteric and allosteric GABAAR binding sites in the DLPFC in schizophrenia that may be related to a “shift” in subunit composition towards α4 and γ2S respectively, which may compromise normal GABAergic modulation and function. Our results may have implications for the development of treatment strategies that target specific GABAAR receptor subunits.
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Affiliation(s)
- Mathieu Verdurand
- Schizophrenia Research Institute, Sydney, Australia
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organization, Sydney, Australia
| | - Stu G. Fillman
- Schizophrenia Research Institute, Sydney, Australia
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Cynthia Shannon Weickert
- Schizophrenia Research Institute, Sydney, Australia
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Katerina Zavitsanou
- Schizophrenia Research Institute, Sydney, Australia
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Sydney, Australia
- School of Psychiatry, University of New South Wales, Sydney, Australia
- * E-mail:
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25
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Engin E, Liu J, Rudolph U. α2-containing GABA(A) receptors: a target for the development of novel treatment strategies for CNS disorders. Pharmacol Ther 2012; 136:142-52. [PMID: 22921455 DOI: 10.1016/j.pharmthera.2012.08.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 08/01/2012] [Indexed: 10/28/2022]
Abstract
GABA(A) receptors have important physiological functions, as revealed by pharmacological studies and experiments involving gene-targeted mouse models, and are the target of widely used drugs such as the benzodiazepines. In this review, we are summarizing current knowledge about the function of α2-containing GABA(A) receptors, a receptor subtype representing approximately 15-20% of all GABA(A) receptors. This receptor subtype mediates anxiolytic-like, reward-enhancing, and antihyperalgesic actions of diazepam, and has antidepressant-like properties. Secondary insufficiency of α2-containing GABA(A) receptors has been postulated to play a role in the pathogenesis of schizophrenia, and may be involved in cognitive impairment in other disorders. Moreover, polymorphisms in the GABRA2 gene encoding the GABA(A) receptor α2 subunit have been found to be linked to chronic alcohol dependence and to polydrug abuse. Thus, α2-containing GABA(A) receptors are involved in the regulation and/or modulation of emotional behaviors and of chronic pain, and appear to be a valid target for novel therapeutic approaches for the treatment of anxiety, depression, schizophrenia and chronic pain.
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Affiliation(s)
- Elif Engin
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, MA 02478, USA
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26
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Long LE, Lind J, Webster M, Weickert CS. Developmental trajectory of the endocannabinoid system in human dorsolateral prefrontal cortex. BMC Neurosci 2012; 13:87. [PMID: 22827915 PMCID: PMC3464170 DOI: 10.1186/1471-2202-13-87] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 06/28/2012] [Indexed: 12/11/2022] Open
Abstract
Background Endocannabinoids provide control over cortical neurotransmission. We investigated the developmental expression of key genes in the endocannabinoid system across human postnatal life and determined whether they correspond to the development of markers for inhibitory interneurons, which shape cortical development. We used microarray with qPCR validation and in situ hybridisation to quantify mRNA for the central endocannabinoid receptor CB1R, endocannabinoid synthetic enzymes (DAGLα for 2-arachidonylglycerol [2-AG] and NAPE-PLD for anandamide), and inactivating enzymes (MGL and ABHD6 for 2-AG and FAAH for anandamide) in human dorsolateral prefrontal cortex (39 days - 49 years). Results CB1R mRNA decreases until adulthood, particularly in layer II, after peaking between neonates and toddlers. DAGLα mRNA expression is lowest in early life and adulthood, peaking between school age and young adulthood. MGL expression declines after peaking in infancy, while ABHD6 increases from neonatal age. NAPE-PLD and FAAH expression increase steadily after infancy, peaking in adulthood. Conclusions Stronger endocannabinoid regulation of presynaptic neurotransmission in both supragranular and infragranular cortical layers as indexed through higher CB1R mRNA may occur within the first few years of human life. After adolescence, higher mRNA levels of the anandamide synthetic and inactivating enzymes NAPE-PLD and FAAH suggest that a late developmental switch may occur where anandamide is more strongly regulated after adolescence than earlier in life. Thus, expression of key genes in the endocannabinoid system changes with maturation of cortical function.
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Affiliation(s)
- Leonora E Long
- Schizophrenia Research Institute, Darlinghurst, NSW 2010, Australia
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Anxiety in liver X receptor β knockout female mice with loss of glutamic acid decarboxylase in ventromedial prefrontal cortex. Proc Natl Acad Sci U S A 2012; 109:7493-8. [PMID: 22529354 DOI: 10.1073/pnas.1205189109] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Anxiety disorders are the most prevalent mental disorders in adolescents in the United States. Female adolescents are more likely than males to be affected with anxiety disorders, but less likely to have behavioral and substance abuse disorders. The prefrontal cortex (PFC), amygdala, and dorsal raphe are known to be involved in anxiety disorders. Inhibitory input from the PFC to the amygdala controls fear and anxiety typically originating in the amygdala, and disruption of the inhibitory input from the PFC leads to anxiety, fear, and personality changes. Recent studies have implicated liver X receptor β (LXRβ) in key neurodevelopmental processes and neurodegenerative diseases. In the present study, we used elevated plus-maze, startle and prepulse inhibition, open field, and novel object recognition tests to evaluate behavior in female LXRβ KO (LXRβ(-/-)) mice. We found that the female LXRβ(-/-) mice were anxious with impaired behavioral responses but normal locomotion and memory. Immunohistochemistry analysis revealed decreased expression of the enzyme responsible for GABA synthesis, glutamic acid decarboxylase (65+67), in the ventromedial PFC. Expression of tryptophan hydroxylase 2 in the dorsal raphe was normal. We conclude that the anxiogenic phenotype in female LXRβ(-/-) mice is caused by reduced GABAergic input from the ventromedial PFC to the amygdala.
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Gurba KN, Hernandez CC, Hu N, Macdonald RL. GABRB3 mutation, G32R, associated with childhood absence epilepsy alters α1β3γ2L γ-aminobutyric acid type A (GABAA) receptor expression and channel gating. J Biol Chem 2012; 287:12083-97. [PMID: 22303015 DOI: 10.1074/jbc.m111.332528] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A GABA(A) receptor β3 subunit mutation, G32R, has been associated with childhood absence epilepsy. We evaluated the possibility that this mutation, which is located adjacent to the most N-terminal of three β3 subunit N-glycosylation sites, might reduce GABAergic inhibition by increasing glycosylation of β3 subunits. The mutation had three major effects on GABA(A) receptors. First, coexpression of β3(G32R) subunits with α1 or α3 and γ2L subunits in HEK293T cells reduced surface expression of γ2L subunits and increased surface expression of β3 subunits, suggesting a partial shift from ternary αβ3γ2L receptors to binary αβ3 and homomeric β3 receptors. Second, β3(G32R) subunits were more likely than β3 subunits to be N-glycosylated at Asn-33, but increases in glycosylation were not responsible for changes in subunit surface expression. Rather, both phenomena could be attributed to the presence of a basic residue at position 32. Finally, α1β3(G32R)γ2L receptors had significantly reduced macroscopic current density. This reduction could not be explained fully by changes in subunit expression levels (because γ2L levels decreased only slightly) or glycosylation (because reduction persisted in the absence of glycosylation at Asn-33). Single channel recording revealed that α1β3(G32R)γ2L receptors had impaired gating with shorter mean open time. Homology modeling indicated that the mutation altered salt bridges at subunit interfaces, including regions important for subunit oligomerization. Our results suggest both a mechanism for mutation-induced hyperexcitability and a novel role for the β3 subunit N-terminal α-helix in receptor assembly and gating.
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Affiliation(s)
- Katharine N Gurba
- Program in Neuroscience, Vanderbilt University, Nashville, Tennessee 37232, USA
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GABA neuron alterations, cortical circuit dysfunction and cognitive deficits in schizophrenia. Neural Plast 2011; 2011:723184. [PMID: 21904685 PMCID: PMC3167184 DOI: 10.1155/2011/723184] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 05/01/2011] [Indexed: 01/01/2023] Open
Abstract
Schizophrenia is a brain disorder associated with cognitive deficits that severely affect the patients' capacity for daily functioning. Whereas our understanding of its pathophysiology is limited, postmortem studies suggest that schizophrenia is associated with deficits of GABA-mediated synaptic transmission. A major role of GABA-mediated transmission may be producing synchronized network oscillations which are currently hypothesized to be essential for normal cognitive function. Therefore, cognitive deficits in schizophrenia may result from a GABA synapse dysfunction that disturbs neural synchrony. Here, we highlight recent studies further suggesting alterations of GABA transmission and network oscillations in schizophrenia. We also review current models for the mechanisms of GABA-mediated synchronization of neural activity, focusing on parvalbumin-positive GABA neurons, which are altered in schizophrenia and whose function has been strongly linked to the production of neural synchrony. Alterations of GABA signaling that impair gamma oscillations and, as a result, cognitive function suggest paths for novel therapeutic interventions.
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Lambe EK, Fillman SG, Webster MJ, Shannon Weickert C. Serotonin receptor expression in human prefrontal cortex: balancing excitation and inhibition across postnatal development. PLoS One 2011; 6:e22799. [PMID: 21829518 PMCID: PMC3146513 DOI: 10.1371/journal.pone.0022799] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 07/05/2011] [Indexed: 12/15/2022] Open
Abstract
Serotonin and its receptors (HTRs) play critical roles in brain development and in the regulation of cognition, mood, and anxiety. HTRs are highly expressed in human prefrontal cortex and exert control over prefrontal excitability. The serotonin system is a key treatment target for several psychiatric disorders; however, the effectiveness of these drugs varies according to age. Despite strong evidence for developmental changes in prefrontal Htrs of rodents, the developmental regulation of HTR expression in human prefrontal cortex has not been examined. Using postmortem human prefrontal brain tissue from across postnatal life, we investigated the expression of key serotonin receptors with distinct inhibitory (HTR1A, HTR5A) and excitatory (HTR2A, HTR2C, HTR4, HTR6) effects on cortical neurons, including two receptors which appear to be expressed to a greater degree in inhibitory interneurons of cerebral cortex (HTR2C, HTR6). We found distinct developmental patterns of expression for each of these six HTRs, with profound changes in expression occurring early in postnatal development and also into adulthood. However, a collective look at these HTRs in terms of their likely neurophysiological effects and major cellular localization leads to a model that suggests developmental changes in expression of these individual HTRs may not perturb an overall balance between inhibitory and excitatory effects. Examining and understanding the healthy balance is critical to appreciate how abnormal expression of an individual HTR may create a window of vulnerability for the emergence of psychiatric illness.
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Affiliation(s)
- Evelyn K Lambe
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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Fabiano V, Mameli C, Zuccotti GV. Adverse drug reactions in newborns, infants and toddlers: pediatric pharmacovigilance between present and future. Expert Opin Drug Saf 2011; 11:95-105. [PMID: 21548838 DOI: 10.1517/14740338.2011.584531] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
INTRODUCTION The detection, assessment, understanding and prevention of adverse drug reactions (ADRs) are the primary aims of pharmacovigilance activities. Pediatric patients, especially all newborns and infants, are particularly at risk for experiencing drug-related adverse events. AREAS COVERED This review briefly analyzes the physiological peculiarities of pharmacodynamic and pharmacokinetic aspects of drugs in newborns, infants and toddlers and children. It also deals with specific pediatric pharmacovigilance aspects, such as the frequent use of unlicensed and/or off-label drugs in neonatal intensive care units in European countries and in Australia. This review reports on European, American and Canadian data about the incidence and type of pediatric ADRs, particularly focusing on neonates, infants and toddlers. EXPERT OPINION The awareness of pediatricians about the importance of reporting ADRs should be stimulated, new reporting systems should be encouraged and pediatric pharmacovigilance activities should be improved, first, by intensifying active post-marketing surveillance methods.
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Affiliation(s)
- Valentina Fabiano
- Luigi Sacco Hospital, Department of Pediatrics, Università degli Studi di Milano, Via GB Grassi, 74, 20157, Milan, Italy.
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Hoftman GD, Lewis DA. Postnatal developmental trajectories of neural circuits in the primate prefrontal cortex: identifying sensitive periods for vulnerability to schizophrenia. Schizophr Bull 2011; 37:493-503. [PMID: 21505116 PMCID: PMC3080694 DOI: 10.1093/schbul/sbr029] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a disorder of cognitive neurodevelopment with characteristic abnormalities in working memory attributed, at least in part, to alterations in the circuitry of the dorsolateral prefrontal cortex. Various environmental exposures from conception through adolescence increase risk for the illness, possibly by altering the developmental trajectories of prefrontal cortical circuits. Macaque monkeys provide an excellent model system for studying the maturation of prefrontal cortical circuits. Here, we review the development of glutamatergic and γ-aminobutyric acid (GABA)-ergic circuits in macaque monkey prefrontal cortex and discuss how these trajectories may help to identify sensitive periods during which environmental exposures, such as those associated with increased risk for schizophrenia, might lead to the types of abnormalities in prefrontal cortical function present in schizophrenia.
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Affiliation(s)
- Gil D. Hoftman
- Medical Scientist Training Program, University of Pittsburgh, Pittsburgh, PA,Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA
| | - David A. Lewis
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA,Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA,To whom correspondence should be addressed; 3811 O'Hara Street, Biomedical Science Tower, W-1654, Pittsburgh, PA 15213, US; tel: 412-383-8548, fax: 412-624-9910, e-mail:
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Beneyto M, Lewis DA. Insights into the neurodevelopmental origin of schizophrenia from postmortem studies of prefrontal cortical circuitry. Int J Dev Neurosci 2011; 29:295-304. [PMID: 20797429 PMCID: PMC3319737 DOI: 10.1016/j.ijdevneu.2010.08.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 08/13/2010] [Accepted: 08/17/2010] [Indexed: 12/19/2022] Open
Abstract
The hypothesis that schizophrenia results from a developmental, as opposed to a degenerative, process affecting the connectivity and network plasticity of the cerebral cortex is supported by findings from morphological and molecular postmortem studies. Specifically, abnormalities in the expression of protein markers of GABA neurotransmission and the lamina- and circuit-specificity of these changes in the cortex in schizophrenia, in concert with knowledge of their developmental trajectories, offer crucial insight into the vulnerability of specific cortical networks to environmental insults during different periods of development. These findings reveal potential targets for therapeutic interventions to improve cognitive function in individuals with schizophrenia, and provide guidance for future preventive strategies to preserve cortical neurotransmission in at-risk individuals.
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Affiliation(s)
- Monica Beneyto
- Department of Psychiatry, University of Pittsburgh, W1656 Biomedical Science Tower, 3811 O'Hara Street, Pittsburgh, PA 15213, USA.
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Fung SJ, Webster MJ, Weickert CS. Expression of VGluT1 and VGAT mRNAs in human dorsolateral prefrontal cortex during development and in schizophrenia. Brain Res 2011; 1388:22-31. [PMID: 21396926 DOI: 10.1016/j.brainres.2011.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 03/02/2011] [Indexed: 01/16/2023]
Abstract
A balance between excitatory and inhibitory neurotransmission is important in normal brain function, and in schizophrenia a deficit in γ-aminobutyric acid (GABA)ergic inhibitory neurotransmission has been indicated by postmortem studies. We examined the ratio of excitatory to inhibitory vesicular neurotransmitter transporter mRNAs (VGluT1 to VGAT) and their ratio in the dorsolateral prefrontal cortex during normal human development and in people with schizophrenia and controls by quantitative RT-PCR. The ratio of VGluT1/VGAT increased gradually in development to reach a peak at school age (5-12 years), after which levels remained fairly constant into adulthood. The VGluT1 mRNA/VGAT mRNA ratio was unchanged in schizophrenia, as was the ratio of complexin 2 mRNA to complexin 1 mRNA (related to synaptic vesicle fusion in excitatory and inhibitory terminals, respectively). This suggests that the excitatory/inhibitory balance is attained prior to adolescence and is maintained across the rest of the life-span and also indicates that in schizophrenia this balance is not greatly disturbed.
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Affiliation(s)
- Samantha J Fung
- Schizophrenia Research Institute, Sydney, New South Wales, Australia
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Rissman RA, Mobley WC. Implications for treatment: GABAA receptors in aging, Down syndrome and Alzheimer's disease. J Neurochem 2011; 117:613-22. [PMID: 21388375 DOI: 10.1111/j.1471-4159.2011.07237.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In addition to progressive dementia, Alzheimer's disease (AD) is characterized by increased incidence of seizure activity. Although originally discounted as a secondary process occurring as a result of neurodegeneration, more recent data suggest that alterations in excitatory-inhibitory (E/I) balance occur in AD and may be a primary mechanism contributing AD cognitive decline. In this study, we discuss relevant research and reports on the GABA(A) receptor in developmental disorders, such as Down syndrome, in healthy aging, and highlight documented aberrations in the GABAergic system in AD. Stressing the importance of understanding the subunit composition of individual GABA(A) receptors, investigations demonstrate alterations of particular GABA(A) receptor subunits in AD, but overall sparing of the GABAergic system. In this study, we review experimental data on the GABAergic system in the pathobiology of AD and discuss relevant therapeutic implications. When developing AD therapeutics that modulate GABA it is important to consider how E/I balance impacts AD pathogenesis and the relationship between seizure activity and cognitive decline.
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Affiliation(s)
- Robert A Rissman
- Department of Neurosciences, University of California, San Diego, La Jolla, California 92093-0624, USA.
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Webster MJ, Elashoff M, Weickert CS. Molecular evidence that cortical synaptic growth predominates during the first decade of life in humans. Int J Dev Neurosci 2010; 29:225-36. [PMID: 20888897 DOI: 10.1016/j.ijdevneu.2010.09.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 09/03/2010] [Accepted: 09/07/2010] [Indexed: 01/02/2023] Open
Abstract
Theories concerning the pathology of human neurodevelopmental disorders that emerge in adolescence, such as schizophrenia, often hypothesize that there may be a failure of normal cortical synaptic loss or pruning. However, direct evidence that synaptic regression is a major developmental event in the adolescent human cortex is limited. Furthermore, developmental work in rodents suggested that synaptic regression in adolescence is not a major feature of cortical development. Thus, we set out to determine when and to what extent molecular markers of synaptic terminals [synaptophysin (SYP), SNAP-25, syntaxin1A (STX1A), and vesicle-associated membrane protein 1 (VAMP1)] are reduced during postnatal human life spanning from 1 month to 45 years (n = 69) using several different quantitative methods, microarray, qPCR and immunoblotting. We found little evidence for a consistent decrease in synaptic-related molecular markers at any time point, but instead found clear patterns of gradual increases in expression of some presynaptic markers with postnatal age (including SNAP-25, VAMP1 and complexin 1 (CPLX1) mRNAs and 6/6 presynaptic proteins evaluated). A measure of synaptic plasticity [growth-associated protein of 43 kDa (GAP-43)] was elevated in neonates, and continued robust expression throughout life. Since CPLX1 protein is enriched in inhibitory terminals we also tested if the protein product of complexin 2 (CPLX2), which is enriched in excitatory neurons, is more specifically reduced in development. In contrast to CPLX1, which showed a steady increase in both mRNA and protein levels during postnatal development (both r > 0.58, p < 0.001), CPLX2 mRNA decreased from infants to toddlers (r = -0.56, p < 0.001), while CPLX2 protein showed a steady increase until young adulthood (r = 0.55, p < 0.001). Furthermore, we found that indices of the dendrites [microtubule associated protein 2 (MAP2)] and spines (spinophilin and postsynaptic density protein of 95 kDa (PSD95)] showed some evidence of reduction over time at the mRNA level but the opposite pattern, of a developmental increase, was found for PSD95 and spinophilin protein levels. Taken together, the postnatal changes in molecular components of synapses supports the notion that growth and strengthening of synaptic elements is a major developmental event occurring in the frontal cortex throughout childhood and that maintenance of steady state levels of synapse-associated molecules may predominate during human adolescence.
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Affiliation(s)
- Maree J Webster
- Stanley Medical Research Institute, 9800 Medical Center Drive, Rockville, MD 20850, USA.
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