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Egerton A, Grace AA, Stone J, Bossong MG, Sand M, McGuire P. Glutamate in schizophrenia: Neurodevelopmental perspectives and drug development. Schizophr Res 2020; 223:59-70. [PMID: 33071070 DOI: 10.1016/j.schres.2020.09.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 08/12/2020] [Accepted: 09/20/2020] [Indexed: 12/14/2022]
Abstract
Research into the neurobiological processes that may lead to the onset of schizophrenia places growing emphasis on the glutamatergic system and brain development. Preclinical studies have shown that neurodevelopmental, genetic, and environmental factors contribute to glutamatergic dysfunction and schizophrenia-related phenotypes. Clinical research has suggested that altered brain glutamate levels may be present before the onset of psychosis and relate to outcome in those at clinical high risk. After psychosis onset, glutamate dysfunction may also relate to the degree of antipsychotic response and clinical outcome. These findings support ongoing efforts to develop pharmacological interventions that target the glutamate system and could suggest that glutamatergic compounds may be more effective in specific patient subgroups or illness stages. In this review, we consider the updated glutamate hypothesis of schizophrenia, from a neurodevelopmental perspective, by reviewing recent preclinical and clinical evidence, and discuss the potential implications for novel therapeutics.
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Affiliation(s)
- Alice Egerton
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
| | - Anthony A Grace
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - James Stone
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Matthijs G Bossong
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Michael Sand
- Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, CT, USA
| | - Philip McGuire
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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2
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Pei JC, Hung WL, Lin BX, Shih MH, Lu LY, Luo DZ, Tai HC, Studer V, Min MY, Lai WS. Therapeutic potential and underlying mechanism of sarcosine (N-methylglycine) in N-methyl-D-aspartate (NMDA) receptor hypofunction models of schizophrenia. J Psychopharmacol 2019; 33:1288-1302. [PMID: 31294644 DOI: 10.1177/0269881119856558] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Compelling animal and clinical studies support the N-methyl-D-aspartate receptor (NMDAR) hypofunction hypothesis of schizophrenia and suggest promising pharmacological agents to ameliorate negative and cognitive symptoms of schizophrenia, including sarcosine, a glycine transporter-1 inhibitor. AIMS AND METHODS It is imperative to evaluate the therapeutic potential of sarcosine in animal models, which provide indispensable tools for testing drug effects in detail and elucidating the underlying mechanisms. In this study, a series of seven experiments was conducted to investigate the effect of sarcosine in ameliorating behavioral deficits and the underlying mechanism in pharmacological (i.e., MK-801-induced) and genetic (i.e., serine racemase-null mutant (SR-/-) mice) NMDAR hypofunction models. RESULTS In Experiment 1, the acute administration of 500/1000 mg/kg sarcosine (i.p.) had no adverse effects on motor function and serum biochemical responses. In Experiments 2-4, sarcosine significantly alleviated MK-801-induced (0.2 mg/kg) brain abnormalities and behavioral deficits in MK-801-induced and SR-/- mouse models. In Experiment 5, the injection of sarcosine enhanced CSF levels of glycine and serine in rat brain. In Experiments 6-7, we show for the first time that sarcosine facilitated NMDAR-mediated hippocampal field excitatory postsynaptic potentials and influenced the movement of surface NMDARs at extrasynaptic sites. CONCLUSIONS Sarcosine effectively regulated the surface trafficking of NMDARs, NMDAR-evoked electrophysiological activity, brain glycine levels and MK-801-induced abnormalities in the brain, which contributed to the amelioration of behavioral deficits in mouse models of NMDAR hypofunction.
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Affiliation(s)
- Ju-Chun Pei
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Wei-Li Hung
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Bei-Xuan Lin
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Min-Han Shih
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Liang-Yin Lu
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Da-Zhong Luo
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Hwan-Ching Tai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Vincent Studer
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France.,French National Center for Scientific Research (CNRS), Bordeaux, France
| | - Ming-Yuan Min
- Institute of Zoology, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
| | - Wen-Sung Lai
- Department of Psychology, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan.,Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
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3
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MacDonald ML, Favo D, Garver M, Sun Z, Arion D, Ding Y, Yates N, Sweet RA, Lewis DA. Laser capture microdissection-targeted mass spectrometry: a method for multiplexed protein quantification within individual layers of the cerebral cortex. Neuropsychopharmacology 2019; 44:743-748. [PMID: 30390066 PMCID: PMC6372704 DOI: 10.1038/s41386-018-0260-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/17/2018] [Indexed: 11/09/2022]
Abstract
The mammalian neocortex is organized into layers distinguished by the size, packing density, and connectivity of their constituent neurons. Many neuropsychiatric illnesses are complex trait disorders with etiologic factors converging on neuronal protein networks. Cortical pathology of neuropsychiatric diseases, such as schizophrenia, is often restricted to, or more pronounced in, certain cortical layers, suggesting that genetic vulnerabilities manifest with laminar specificity. Thus, the ability to investigate cortical layer-specific protein levels in human postmortem brain is highly desirable. Here, we developed and validated a laser capture microdissection-mass spectrometry (LCM-MS) approach to quantify over 200 proteins in cortical layers 3 and 5 of two cohorts of human subjects as well as a monkey model of postmortem interval. LCM-MS was readily implementable and reliably identified protein patterns that differed between cortical layers 3 and 5. Our findings suggest that LCM-MS facilitates the precise quantification of proteins within individual cortical layers from human postmortem brain tissue, providing a powerful tool in the study of neuropsychiatric disease.
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Affiliation(s)
- Matthew L MacDonald
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
- Biomedical Mass Spectrometry Center, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Daley Favo
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Megan Garver
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zhe Sun
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Dominique Arion
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ying Ding
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nathan Yates
- Biomedical Mass Spectrometry Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Robert A Sweet
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
| | - David A Lewis
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
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4
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Mohammadi A, Rashidi E, Amooeian VG. Brain, blood, cerebrospinal fluid, and serum biomarkers in schizophrenia. Psychiatry Res 2018; 265:25-38. [PMID: 29680514 DOI: 10.1016/j.psychres.2018.04.036] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 03/20/2018] [Accepted: 04/11/2018] [Indexed: 12/29/2022]
Abstract
Over the last decade, finding a reliable biomarker for the early detection of schizophrenia (Scz) has been a topic of interest. The main goal of the current review is to provide a comprehensive view of the brain, blood, cerebrospinal fluid (CSF), and serum biomarkers of Scz disease. Imaging studies have demonstrated that the volumes of the corpus callosum, thalamus, hippocampal formation, subiculum, parahippocampal gyrus, superior temporal gyrus, prefrontal and orbitofrontal cortices, and amygdala-hippocampal complex were reduced in patients diagnosed with Scz. It has been revealed that the levels of interleukin 1β (IL-1β), IL-6, IL-8, and TNF-α were increased in patients with Scz. Decreased mRNA levels of brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), neurotrophin-3 (NT-3), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF) genes have also been reported in Scz patients. Genes with known strong relationships with this disease include BDNF, catechol-O-methyltransferase (COMT), regulator of G-protein signaling 4 (RGS4), dystrobrevin-binding protein 1 (DTNBP1), neuregulin 1 (NRG1), Reelin (RELN), Selenium-binding protein 1 (SELENBP1), glutamic acid decarboxylase 67 (GAD 67), and disrupted in schizophrenia 1 (DISC1). The levels of dopamine, tyrosine hydroxylase (TH), serotonin or 5-hydroxytryptamine (5-HT) receptor 1A and B (5-HTR1A and 5-HTR1B), and 5-HT1B were significantly increased in Scz patients, while the levels of gamma-aminobutyric acid (GABA), 5-HT transporter (5-HTT), and 5-HT receptor 2A (5-HTR2A) were decreased. The increased levels of SELENBP1 and Glycogen synthase kinase 3 subunit α (GSK3α) genes in contrast with reduced levels of B-cell translocation gene 1 (BTG1), human leukocyte antigen DRB1 (HLA-DRB1), heterogeneous nuclear ribonucleoprotein A3 (HNRPA3), and serine/arginine-rich splicing factor 1 (SFRS1) genes have also been reported. This review covers various dysregulation of neurotransmitters and also highlights the strengths and weaknesses of studies attempting to identify candidate biomarkers.
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Affiliation(s)
- Alireza Mohammadi
- Neuroscience Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Ehsan Rashidi
- Students' Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
| | - Vahid Ghasem Amooeian
- Students' Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
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5
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Huang XF, Song X. Effects of antipsychotic drugs on neurites relevant to schizophrenia treatment. Med Res Rev 2018; 39:386-403. [PMID: 29785841 DOI: 10.1002/med.21512] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 04/06/2018] [Accepted: 04/30/2018] [Indexed: 12/31/2022]
Abstract
Although antipsychotic drugs are mainly used for treating schizophrenia, they are widely used for treating various psychiatric diseases in adults, the elderly, adolescents and even children. Today, about 1.2% of the worldwide population suffers from psychosis and related disorders, which translates to about 7.5 million subjects potentially targeted by antipsychotic drugs. Neurites project from the cell body of neurons and connect neurons to each other to form neural networks. Deficits in neurite outgrowth and integrity are implicated in psychiatric diseases including schizophrenia. Neurite deficits contribute to altered brain development, neural networking and connectivity as well as symptoms including psychosis and altered cognitive function. This review revealed that (1) antipsychotic drugs could have profound effects on neurites, synaptic spines and synapse, by which they may influence and regulate neural networking and plasticity; (2) antipsychotic drugs target not only neurotransmitter receptors but also intracellular signaling molecules regulating the signaling pathways responsible for neurite outgrowth and maintenance; (3) high doses and chronic administration of antipsychotic drugs may cause some loss of neurites, synaptic spines, or synapsis in the cortical structures. In addition, confounding effects causing neurite deficits may include elevated inflammatory cytokines and antipsychotic drug-induced metabolic side effects in patients on chronic antipsychotic therapy. Unraveling how antipsychotic drugs affect neurites and neural connectivity is essential for improving therapeutic outcomes and preventing aversive effects for patients on antipsychotic drug treatment.
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Affiliation(s)
- Xu-Feng Huang
- Henan Medical Key Laboratory of Translational Research on Psychiatric Diseases, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,The Illawarra Health and Medical Research Institute and School of Medicine, University of Wollongong, Wollongong, Australia
| | - Xueqin Song
- Henan Medical Key Laboratory of Translational Research on Psychiatric Diseases, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
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6
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Perkovic MN, Erjavec GN, Strac DS, Uzun S, Kozumplik O, Pivac N. Theranostic Biomarkers for Schizophrenia. Int J Mol Sci 2017; 18:E733. [PMID: 28358316 PMCID: PMC5412319 DOI: 10.3390/ijms18040733] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 03/23/2017] [Accepted: 03/27/2017] [Indexed: 12/14/2022] Open
Abstract
Schizophrenia is a highly heritable, chronic, severe, disabling neurodevelopmental brain disorder with a heterogeneous genetic and neurobiological background, which is still poorly understood. To allow better diagnostic procedures and therapeutic strategies in schizophrenia patients, use of easy accessible biomarkers is suggested. The most frequently used biomarkers in schizophrenia are those associated with the neuroimmune and neuroendocrine system, metabolism, different neurotransmitter systems and neurotrophic factors. However, there are still no validated and reliable biomarkers in clinical use for schizophrenia. This review will address potential biomarkers in schizophrenia. It will discuss biomarkers in schizophrenia and propose the use of specific blood-based panels that will include a set of markers associated with immune processes, metabolic disorders, and neuroendocrine/neurotrophin/neurotransmitter alterations. The combination of different markers, or complex multi-marker panels, might help in the discrimination of patients with different underlying pathologies and in the better classification of the more homogenous groups. Therefore, the development of the diagnostic, prognostic and theranostic biomarkers is an urgent and an unmet need in psychiatry, with the aim of improving diagnosis, therapy monitoring, prediction of treatment outcome and focus on the personal medicine approach in order to improve the quality of life in patients with schizophrenia and decrease health costs worldwide.
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Affiliation(s)
| | | | - Dubravka Svob Strac
- Rudjer Boskovic Institute, Division of Molecular Medicine, 10000 Zagreb, Croatia.
| | - Suzana Uzun
- Clinic for Psychiatry Vrapce, 10090 Zagreb, Croatia.
| | | | - Nela Pivac
- Rudjer Boskovic Institute, Division of Molecular Medicine, 10000 Zagreb, Croatia.
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7
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Boerner T, Bygrave AM, Chen J, Fernando A, Jackson S, Barkus C, Sprengel R, Seeburg PH, Harrison PJ, Gilmour G, Bannerman DM, Sanderson DJ. The group II metabotropic glutamate receptor agonist LY354740 and the D2 receptor antagonist haloperidol reduce locomotor hyperactivity but fail to rescue spatial working memory in GluA1 knockout mice. Eur J Neurosci 2017; 45:912-921. [PMID: 28186680 PMCID: PMC5396315 DOI: 10.1111/ejn.13539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/18/2017] [Accepted: 02/07/2017] [Indexed: 12/21/2022]
Abstract
Group II metabotropic glutamate receptor agonists have been suggested as potential anti‐psychotics, at least in part, based on the observation that the agonist LY354740 appeared to rescue the cognitive deficits caused by non‐competitive N‐methyl‐d‐aspartate receptor (NMDAR) antagonists, including spatial working memory deficits in rodents. Here, we tested the ability of LY354740 to rescue spatial working memory performance in mice that lack the GluA1 subunit of the AMPA glutamate receptor, encoded by Gria1, a gene recently implicated in schizophrenia by genome‐wide association studies. We found that LY354740 failed to rescue the spatial working memory deficit in Gria1−/− mice during rewarded alternation performance in the T‐maze. In contrast, LY354740 did reduce the locomotor hyperactivity in these animals to a level that was similar to controls. A similar pattern was found with the dopamine receptor antagonist haloperidol, with no amelioration of the spatial working memory deficit in Gria1−/− mice, even though the same dose of haloperidol reduced their locomotor hyperactivity. These results with LY354740 contrast with the rescue of spatial working memory in models of glutamatergic hypofunction using non‐competitive NMDAR antagonists. Future studies should determine whether group II mGluR agonists can rescue spatial working memory deficits with other NMDAR manipulations, including genetic models and other pharmacological manipulations of NMDAR function.
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Affiliation(s)
- Thomas Boerner
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Alexei M Bygrave
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Jingkai Chen
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Anushka Fernando
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Stephanie Jackson
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Chris Barkus
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - Rolf Sprengel
- Max Planck Research Group, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Peter H Seeburg
- Max Planck Research Group, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Paul J Harrison
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK
| | - Gary Gilmour
- Lilly Centre for Cognitive Neuroscience, Discovery Biology, Lilly Research Centre, Lilly UK, Windlesham, Surrey, UK
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, 9 South Parks, Oxford, OX1 3UD, UK
| | - David J Sanderson
- Department of Psychology, Durham University, Science Site, South Road, Durham, DH1 3LE, UK
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8
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Treen D, Batlle S, Mollà L, Forcadell E, Chamorro J, Bulbena A, Perez V. Are there glutamate abnormalities in subjects at high risk mental state for psychosis? A review of the evidence. Schizophr Res 2016; 171:166-75. [PMID: 26803691 DOI: 10.1016/j.schres.2016.01.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 11/29/2015] [Accepted: 01/01/2016] [Indexed: 02/07/2023]
Abstract
New approaches to underlying alterations in psychosis suggest increasing evidence of glutamatergic abnormalities in schizophrenia and an association between these abnormalities and certain core psychopathological alterations such as cognitive impairment and negative symptoms. Proton magnetic resonance spectroscopy ((1)H MRS) is an MR-based technique that enables investigators to study glutamate function by measuring in vivo glutamatergic indices in the brain. In this article we review the published studies of (1)H MRS in subjects with an at-risk mental state (ARMS) for psychosis. The primary aim was to investigate whether alterations in glutamate function are present before the illness develops in order to expand our understanding of glutamatergic abnormalities in prodromal phases. Three databases were consulted for this review. Titles and abstracts were examined to determine if they fulfilled the inclusion criteria. The reference lists of the included studies were also examined to identify additional trials. Eleven final studies were included in this review. Significant alterations in glutamate metabolites across different cerebral areas (frontal lobe, thalamus, and the associative striatum) in subjects with an ARMS for psychosis are reported in six of the trials. A longitudinal analysis in two of these trials confirmed an association between these abnormalities and worsening of symptoms and final transition to psychosis. Considering that five other studies found no significant differences across these same areas, we can conclude that more research is needed to confirm glutamatergic abnormalities in subjects with an ARMS for psychosis. However, future research must overcome the methodological limitations of existing studies to obtain reliable results.
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Affiliation(s)
- Devi Treen
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain
| | - Santiago Batlle
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain
| | - Laia Mollà
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain
| | - Eduard Forcadell
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain
| | - Jacobo Chamorro
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain
| | - Antonio Bulbena
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain; Autonomous University of Barcelona UAB, Department of Psychiatry and Forensic Medicine, Bellaterra, Spain
| | - Victor Perez
- Institut de Neuropsiquiatria i Addiccions, Hospital del Mar, Barcelona, Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain; Autonomous University of Barcelona UAB, Department of Psychiatry and Forensic Medicine, Bellaterra, Spain; Centro de Investigación Biomédica en Red de Salud Mental CIBERSAM, Spain
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9
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Abstract
Over 100 loci are now associated with schizophrenia risk as identified by single nucleotide polymorphisms (SNPs) in genome-wide association studies. These findings mean that 'genes for schizophrenia' have unquestionably been found. However, many questions remain unanswered, including several which affect their therapeutic significance. The SNPs individually have minor effects, and even cumulatively explain only a modest fraction of the genetic predisposition. The remainder likely results from many more loci, from rare variants, and from gene-gene and gene-environment interactions. The risk SNPs are almost all non-coding, meaning that their biological significance is unclear; probably their effects are mediated via an influence on gene regulation, and emerging evidence suggests that some key molecular events occur during early brain development. The loci include novel genes of unknown function as well as genes and pathways previously implicated in the pathophysiology of schizophrenia, e.g. NMDA receptor signalling. Genes in the latter category have the clearer therapeutic potential, although even this will be a challenging process because of the many complexities concerning the genetic architecture and mediating mechanisms. This review summarises recent schizophrenia genetic findings and some key issues they raise, particularly with regard to their implications for identifying and validating novel drug targets.
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Affiliation(s)
- Paul J Harrison
- University Department of Psychiatry, Warneford Hospital, Oxford, UK
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10
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Barkus C, Sanderson DJ, Rawlins JNP, Walton ME, Harrison PJ, Bannerman DM. What causes aberrant salience in schizophrenia? A role for impaired short-term habituation and the GRIA1 (GluA1) AMPA receptor subunit. Mol Psychiatry 2014; 19:1060-70. [PMID: 25224260 PMCID: PMC4189912 DOI: 10.1038/mp.2014.91] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/19/2014] [Accepted: 06/25/2014] [Indexed: 01/13/2023]
Abstract
The GRIA1 locus, encoding the GluA1 (also known as GluRA or GluR1) AMPA glutamate receptor subunit, shows genome-wide association to schizophrenia. As well as extending the evidence that glutamatergic abnormalities have a key role in the disorder, this finding draws attention to the behavioural phenotype of Gria1 knockout mice. These mice show deficits in short-term habituation. Importantly, under some conditions the attention being paid to a recently presented neutral stimulus can actually increase rather than decrease (sensitization). We propose that this mouse phenotype represents a cause of aberrant salience and, in turn, that aberrant salience (and the resulting positive symptoms) in schizophrenia may arise, at least in part, from a glutamatergic genetic predisposition and a deficit in short-term habituation. This proposal links an established risk gene with a psychological process central to psychosis and is supported by findings of comparable deficits in short-term habituation in mice lacking the NMDAR receptor subunit Grin2a (which also shows association to schizophrenia). As aberrant salience is primarily a dopaminergic phenomenon, the model supports the view that the dopaminergic abnormalities can be downstream of a glutamatergic aetiology. Finally, we suggest that, as illustrated here, the real value of genetically modified mice is not as 'models of schizophrenia' but as experimental tools that can link genomic discoveries with psychological processes and help elucidate the underlying neural mechanisms.
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Affiliation(s)
- C Barkus
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX3 7JX, U.K
| | - DJ Sanderson
- Department of Psychology, Durham University, Durham, DH1 3LE, U.K
| | - JNP Rawlins
- Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford, OX1 3UD, U.K
| | - ME Walton
- Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford, OX1 3UD, U.K
| | - PJ Harrison
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, OX3 7JX, U.K
| | - DM Bannerman
- Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford, OX1 3UD, U.K
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11
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Kiss T, Feng J, Hoffmann W, Shaffer C, Hajós M. Rhythmic theta and delta activity of cortical and hippocampal neuronal networks in genetically or pharmacologically induced N-methyl-d-aspartate receptor hypofunction under urethane anesthesia. Neuroscience 2013; 237:255-67. [DOI: 10.1016/j.neuroscience.2013.01.058] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 01/19/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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12
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Hayashi-Takagi A, Barker PB, Sawa A. Readdressing synaptic pruning theory for schizophrenia: Combination of brain imaging and cell biology. Commun Integr Biol 2011; 4:211-2. [PMID: 21655443 DOI: 10.4161/cib.4.2.14492] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Accepted: 12/12/2010] [Indexed: 11/19/2022] Open
Abstract
Disturbance in the synapse has been suggested in the pathology of schizophrenia, especially through examination of autopsied brains from patients with the disease. Nonetheless, it has been unclear whether and how such disturbance is associated with the onset and progression of the disease in young adulthood. Some studies with magnetic resonance spectroscopy (MRS) have suggested that overpruning of dendritic spines may occur in the prodromal and early stages of schizophrenia. In addition, our recent study indicates that DISC1, a promising risk factor for schizophrenia, has a crucial role in the maintenance of the dendritic spine in association with activation of the NMDA-type glutamate receptor.1 Disturbance of spine maintenance can be linked to aberrant synaptic pruning during postnatal brain maturation. Biological studies with genetic models may provide us with an opportunity to validate experimentally the synaptic pruning theory for schizophrenia. An integrative strategy of brain imaging and cell biology may be a promising approach to address a key biological question for mental illnesses.
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Affiliation(s)
- Akiko Hayashi-Takagi
- Department of Psychiatry; Johns Hopkins University School of Medicine; Baltimore, MD USA
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13
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Ibrahim HM, Tamminga CA. Schizophrenia: treatment targets beyond monoamine systems. Annu Rev Pharmacol Toxicol 2011; 51:189-209. [PMID: 20868275 DOI: 10.1146/annurev.pharmtox.010909.105851] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We develop the proposal in this review that schizophrenia is a syndrome made up of component symptom complexes, each with distinctive clinical correlates, pathophysiology, and selective treatments. Psychosis is the necessary component of the syndrome; it has a young-adult onset and is sensitive to current antipsychotic drugs. Cognitive dysfunction often precedes psychosis onset, does not present an episodic course, and is poorly responsive to antipsychotic drugs. Treatments for cognition are being developed largely on the basis of animal pharmacology. Drugs for component symptom complexes will theoretically be coadministered to independent symptomatic end points. Animal models, some with genetic characteristics, can be more easily and directly developed to match an individual component than to match an illness definition as broad as schizophrenia.
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Affiliation(s)
- Hisham M Ibrahim
- Department of Psychiatry, University of Texas Southwestern, Dallas, 75390-9086, USA.
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Delta oscillation and short-term plasticity in the rat medial prefrontal cortex: modelling NMDA hypofunction of schizophrenia. Int J Neuropsychopharmacol 2011; 14:29-42. [PMID: 20334724 DOI: 10.1017/s1461145710000271] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Dysfunction of the prefrontal cortex (PFC) is considered to be an important factor contributing to a decrease in cognitive performance of schizophrenia patients. The medial PFC (mPFC) is innervated by the hippocampus/subiculum, and the subiculum-mPFC pathway is known to be involved in various cognitive processes. Glutamate-containing subicular axons innervate cortical pyramidal neurons and interneurons where AMPA and NMDA receptors are implicated in synaptic transmission. In our experiments, properties of subiculum-mPFC interactions were studied using pathway stimulation and local field potential (LFP) recordings of the mPFC in urethane-anaesthetized rats. Changes in paired-pulse facilitation (PPF) and LFP oscillations, effects of the NMDA receptor antagonist MK-801, and the AMPAkine LY451395 were evaluated. Effects of disruption of the thalamo-cortical loop with local microinjection of lidocaine into the mediodorsal thalamic nucleus (MD) were also studied. Our findings demonstrate that both systemic administration of MK-801 and local MD lidocaine microinjection produce similar changes in LFP oscillations and reduction in PPF. Specifically, it was observed that MK-801 (0.05 mg/kg i.v.) and intra-thalamic lidocaine changed regular, 2 Hz delta oscillation to a less regular 0.5-1.5 Hz delta rhythm. Concurrently, PPF in response to electrical stimulation of the subiculum was significantly attenuated. Administration of the AMPAkine LY451395 (0.01 mg/kg i.v.) reversed the MK-801- and lidocaine-induced changes, and was itself blocked by the AMPA receptor antagonist CP-465022. Analysis of our findings suggests a critical role of cortical interneurons in NMDA/AMPA receptor-mediated changes in thalamo-cortical oscillations and PPF, and contributes to our understanding of the NMDA hypofunction model of schizophrenia.
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Kiss T, Hoffmann WE, Scott L, Kawabe TT, Milici AJ, Nilsen EA, Hajós M. Role of Thalamic Projection in NMDA Receptor-Induced Disruption of Cortical Slow Oscillation and Short-Term Plasticity. Front Psychiatry 2011; 2:14. [PMID: 21556284 PMCID: PMC3089990 DOI: 10.3389/fpsyt.2011.00014] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Accepted: 03/22/2011] [Indexed: 11/13/2022] Open
Abstract
NMDA receptor (NMDAR) antagonists, such as phencyclidine, ketamine, or dizocilpine (MK-801) are commonly used in psychiatric drug discovery in order to model several symptoms of schizophrenia, including psychosis and impairments in working memory. In spite of the widespread use of NMDAR antagonists in preclinical and clinical studies, our understanding of the mode of action of these drugs on brain circuits and neuronal networks is still limited. In the present study spontaneous local field potential (LFP), multi- (MUA) and single-unit activity, and evoked potential, including paired-pulse facilitation (PPF) in response to electrical stimulation of the ipsilateral subiculum were carried out in the medial prefrontal cortex (mPFC) in urethane anesthetized rats. Systemic administration of MK-801 (0.05 mg/kg, i.v.) decreased overall MUA, with a diverse effect on single-unit activity, including increased, decreased, or unchanged firing, and in line with our previous findings shifted delta-frequency power of the LFP and disrupted PPF (Kiss et al., 2011). In order to provide further insight to the mechanisms of action of NMDAR antagonists, MK-801 was administered intracranially into the mPFC and mediodorsal nucleus of the thalamus (MD). Microinjections of MK-801, but not physiological saline, localized into the MD evoked changes in both LFP parameters and PPF similar to the effects of systemically administered MK-801. Local microinjection of MK-801 into the mPFC was without effect on these parameters. Our findings indicate that the primary site of the action of systemic administration of NMDAR antagonists is unlikely to be the cortex. We presume that multiple neuronal networks, involving thalamic nuclei contribute to disrupted behavior and cognition following NMDAR blockade.
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Affiliation(s)
- Tamás Kiss
- Neuroscience Research Unit, Pfizer Global Research and Development, Pfizer Inc . Groton, CT, USA
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16
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Structural dynamics of dendritic spines in memory and cognition. Trends Neurosci 2010; 33:121-9. [PMID: 20138375 DOI: 10.1016/j.tins.2010.01.001] [Citation(s) in RCA: 595] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 01/07/2010] [Accepted: 01/08/2010] [Indexed: 01/07/2023]
Abstract
Recent studies show that dendritic spines are dynamic structures. Their rapid creation, destruction and shape-changing are essential for short- and long-term plasticity at excitatory synapses on pyramidal neurons in the cerebral cortex. The onset of long-term potentiation, spine-volume growth and an increase in receptor trafficking are coincident, enabling a 'functional readout' of spine structure that links the age, size, strength and lifetime of a synapse. Spine dynamics are also implicated in long-term memory and cognition: intrinsic fluctuations in volume can explain synapse maintenance over long periods, and rapid, activity-triggered plasticity can relate directly to cognitive processes. Thus, spine dynamics are cellular phenomena with important implications for cognition and memory. Furthermore, impaired spine dynamics can cause psychiatric and neurodevelopmental disorders.
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Hayashi-Takagi A, Sawa A. Disturbed synaptic connectivity in schizophrenia: convergence of genetic risk factors during neurodevelopment. Brain Res Bull 2010; 83:140-6. [PMID: 20433911 DOI: 10.1016/j.brainresbull.2010.04.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 02/07/2010] [Accepted: 04/19/2010] [Indexed: 12/13/2022]
Abstract
The pathological mechanisms underlying schizophrenia are unclear. Although genetic susceptibility factors for schizophrenia likely influence neurodevelopmental processes, the onset of the disease is in adolescence and young adulthood. Here we review recent literatures implicating neurodevelopmental deficits in schizophrenia and discuss how genetic factors are involved in the processes toward onset of the disease. We emphasize the importance of postnatal glutamate synapse development in the pathology of the disorder. These genetic risk factors contribute to the process possibly in a synergistic manner. The notion of signal pathways involving more than one genetic factor is in accord with the multifactorial nature of schizophrenia.
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Affiliation(s)
- Akiko Hayashi-Takagi
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States.
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18
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Inoue H, Yamasue H, Tochigi M, Suga M, Iwayama Y, Abe O, Yamada H, Rogers MA, Aoki S, Kato T, Sasaki T, Yoshikawa T, Kasai K. Functional (GT)n polymorphisms in promoter region ofN-methyl-d-aspartate receptor 2A subunit (GRIN2A) gene affect hippocampal and amygdala volumes. GENES BRAIN AND BEHAVIOR 2010; 9:269-75. [DOI: 10.1111/j.1601-183x.2009.00557.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Hayashi-Takagi A, Takaki M, Graziane N, Seshadri S, Murdoch H, Dunlop AJ, Makino Y, Seshadri AJ, Ishizuka K, Srivastava DP, Xie Z, Baraban JM, Houslay MD, Tomoda T, Brandon NJ, Kamiya A, Yan Z, Penzes P, Sawa A. Disrupted-in-Schizophrenia 1 (DISC1) regulates spines of the glutamate synapse via Rac1. Nat Neurosci 2010; 13:327-32. [PMID: 20139976 PMCID: PMC2846623 DOI: 10.1038/nn.2487] [Citation(s) in RCA: 337] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 12/23/2009] [Indexed: 11/17/2022]
Abstract
Synaptic spines are dynamic structures that regulate neuronal responsiveness and plasticity. We examined the role of the schizophrenia risk factor DISC1 in the maintenance of spine morphology and function. We found that DISC1 anchored Kalirin-7 (Kal-7), regulating access of Kal-7 to Rac1 and controlling the duration and intensity of Rac1 activation in response to NMDA receptor activation in both cortical cultures and rat brain in vivo. These results explain why Rac1 and its activator (Kal-7) serve as important mediators of spine enlargement and why constitutive Rac1 activation decreases spine size. This mechanism likely underlies disturbances in glutamatergic neurotransmission that have been frequently reported in schizophrenia that can lead to alteration of dendritic spines with consequential major pathological changes in brain function. Furthermore, the concept of a signalosome involving disease-associated factors, such as DISC1 and glutamate, may well contribute to the multifactorial and polygenetic characteristics of schizophrenia.
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Affiliation(s)
- Akiko Hayashi-Takagi
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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20
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Turnock-Jones JJ, Jennings CA, Robbins MJ, Cluderay JE, Cilia J, Reid JL, Taylor A, Jones DN, Emson PC, Southam E. Increased expression of the NR2A NMDA receptor subunit in the prefrontal cortex of rats reared in isolation. Synapse 2009; 63:836-46. [DOI: 10.1002/syn.20665] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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21
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22
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Lisman JE, Coyle JT, Green RW, Javitt DC, Benes FM, Heckers S, Grace AA. Circuit-based framework for understanding neurotransmitter and risk gene interactions in schizophrenia. Trends Neurosci 2008; 16:e43-71. [PMID: 18395805 DOI: 10.1111/j.1755-5949.2010.00163.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many risk genes interact synergistically to produce schizophrenia and many neurotransmitter interactions have been implicated. We have developed a circuit-based framework for understanding gene and neurotransmitter interactions. NMDAR hypofunction has been implicated in schizophrenia because NMDAR antagonists reproduce symptoms of the disease. One action of antagonists is to reduce the excitation of fast-spiking interneurons, resulting in disinhibition of pyramidal cells. Overactive pyramidal cells, notably those in the hippocampus, can drive a hyperdopaminergic state that produces psychosis. Additional aspects of interneuron function can be understood in this framework, as follows. (i) In animal models, NMDAR antagonists reduce parvalbumin and GAD67, as found in schizophrenia. These changes produce further disinhibition and can be viewed as the aberrant response of a homeostatic system having a faulty activity sensor (the NMDAR). (ii) Disinhibition decreases the power of gamma oscillation and might thereby produce negative and cognitive symptoms. (iii) Nicotine enhances the output of interneurons, and might thereby contribute to its therapeutic effect in schizophrenia.
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Affiliation(s)
- John E Lisman
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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23
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Lisman JE, Coyle JT, Green RW, Javitt DC, Benes FM, Heckers S, Grace AA. Circuit-based framework for understanding neurotransmitter and risk gene interactions in schizophrenia. Trends Neurosci 2008; 31:234-42. [PMID: 18395805 DOI: 10.1016/j.tins.2008.02.005] [Citation(s) in RCA: 745] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 02/12/2008] [Accepted: 02/19/2008] [Indexed: 10/22/2022]
Abstract
Many risk genes interact synergistically to produce schizophrenia and many neurotransmitter interactions have been implicated. We have developed a circuit-based framework for understanding gene and neurotransmitter interactions. NMDAR hypofunction has been implicated in schizophrenia because NMDAR antagonists reproduce symptoms of the disease. One action of antagonists is to reduce the excitation of fast-spiking interneurons, resulting in disinhibition of pyramidal cells. Overactive pyramidal cells, notably those in the hippocampus, can drive a hyperdopaminergic state that produces psychosis. Additional aspects of interneuron function can be understood in this framework, as follows. (i) In animal models, NMDAR antagonists reduce parvalbumin and GAD67, as found in schizophrenia. These changes produce further disinhibition and can be viewed as the aberrant response of a homeostatic system having a faulty activity sensor (the NMDAR). (ii) Disinhibition decreases the power of gamma oscillation and might thereby produce negative and cognitive symptoms. (iii) Nicotine enhances the output of interneurons, and might thereby contribute to its therapeutic effect in schizophrenia.
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Affiliation(s)
- John E Lisman
- Department of Biology, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
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24
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Javitt DC, Spencer KM, Thaker GK, Winterer G, Hajós M. Neurophysiological biomarkers for drug development in schizophrenia. Nat Rev Drug Discov 2008; 7:68-83. [PMID: 18064038 PMCID: PMC2753449 DOI: 10.1038/nrd2463] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Schizophrenia represents a pervasive deficit in brain function, leading to hallucinations and delusions, social withdrawal and a decline in cognitive performance. As the underlying genetic and neuronal abnormalities in schizophrenia are largely unknown, it is challenging to measure the severity of its symptoms objectively, or to design and evaluate psychotherapeutic interventions. Recent advances in neurophysiological techniques provide new opportunities to measure abnormal brain functions in patients with schizophrenia and to compare these with drug-induced alterations. Moreover, many of these neurophysiological processes are phylogenetically conserved and can be modelled in preclinical studies, offering unique opportunities for use as translational biomarkers in schizophrenia drug discovery.
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Affiliation(s)
- Daniel C Javitt
- Nathan Kline Institute for Schizophrenia Research/New York University School of Medicine, 140 Old Orangeburg Road, Orangeburg, New York 10962, USA
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