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Coyle JT. Passing the torch: The ascendance of the glutamatergic synapse in the pathophysiology of schizophrenia. Biochem Pharmacol 2024; 228:116376. [PMID: 38906225 DOI: 10.1016/j.bcp.2024.116376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 06/11/2024] [Accepted: 06/18/2024] [Indexed: 06/23/2024]
Abstract
For nearly fifty years, the dopamine hypothesis has dominated our understanding of the pathophysiology of schizophrenia and provided the lone target for drug development. However, with the exception of clozapine, the dopamine D2 receptor antagonizing anti-psychotic drugs have little impact on the negative symptoms and cognitive deficits, aspects of the disorder that robustly predict outcome. Pathologic studies reveal cortical atrophy and wide-spread loss of glutamatergic synaptic spines, unexplained by dopaminergic malfunction. Recent genome-wide association studies indicate that at least thirty risk genes for schizophrenia encode proteins localized to the glutamatergic synapse and inhibit glutamate neurotransmission, especially at the NMDA receptor. To function, the NMDA receptor requires the binding of glycine (primarily in the cerebellum and brainstem) or D-serine (in forebrain) to the NR1 channel subunit of the NMDA receptor. Genetically silencing the gene (srr) encoding serine racemase, the biosynthetic enzyme for D-serine, results in forebrain NMDA receptor hypofunction. The srr-/- mice have 90 % loss of endogenous D-serine and approximately 70 % decrease in NMDA receptor function. Several animal models of schizophrenia are based on behavioral and pharmacologic strategies, which have negligible validity with regard to the fundamental etiology of schizophrenia. We summarize here the results of a mouse model, in which srr, one of the two dozen or more risk gene for schizophrenia that affect NMDA receptor function, has been inactivated. The srr-/- mice exhibit striking similarities to schizophrenia including cortical atrophy, loss of cortico-limbic glutamatergic synapses, increased sub-cortical dopamine release, EEG abnormalities, and cognitive impairments. The limited efficacy of drugs targeting the glutamatergic synapse on DSM-5 diagnosed criteria for schizophrenia used in clinical trials may reflect the fact that only 30 % of the patients have impaired glutamatergic neurotransmission, resulting from the genetic heterogeneity of the disorder.
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Affiliation(s)
- Joseph T Coyle
- Eben S Draper Professor of Psychiatry and Neuroscience Harvard Medical School (Emeritus), McLean Hospital, 115 Mill St, Belmont, MA 02478, United States.
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2
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Okubo R, Okada M, Motomura E. Dysfunction of the NMDA Receptor in the Pathophysiology of Schizophrenia and/or the Pathomechanisms of Treatment-Resistant Schizophrenia. Biomolecules 2024; 14:1128. [PMID: 39334894 PMCID: PMC11430065 DOI: 10.3390/biom14091128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Revised: 08/29/2024] [Accepted: 09/02/2024] [Indexed: 09/30/2024] Open
Abstract
For several decades, the dopamine hypothesis contributed to the discovery of numerous typical and atypical antipsychotics and was the sole hypothesis for the pathophysiology of schizophrenia. However, neither typical nor atypical antipsychotics, other than clozapine, have been effective in addressing negative symptoms and cognitive impairments, which are indices for the prognostic and disability outcomes of schizophrenia. Following the development of atypical antipsychotics, the therapeutic targets for antipsychotics expanded beyond the blockade of dopamine D2 and serotonin 5-HT2A receptors to explore the partial agonism of the D2 receptor and the modulation of new targets, such as D3, 5-HT1A, 5-HT7, and metabotropic glutamate receptors. Despite these efforts, to date, psychiatry has not successfully developed antipsychotics with antipsychotic properties proven to be superior to those of clozapine. The glutamate hypothesis, another hypothesis regarding the pathophysiology/pathomechanism of schizophrenia, was proposed based on clinical findings that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, such as phencyclidine and ketamine, induce schizophrenia-like psychotic episodes. Large-scale genome-wide association studies (GWASs) revealed that approximately 30% of the risk genes for schizophrenia (the total number was over one hundred) encode proteins associated with glutamatergic transmission. These findings supported the validation of the glutamate hypothesis, which was inspired by the clinical findings regarding NMDAR antagonists. Additionally, these clinical and genetic findings suggest that schizophrenia is possibly a syndrome with complicated pathomechanisms that are affected by multiple biological and genetic vulnerabilities. The glutamate hypothesis has been the most extensively investigated pathophysiology/pathomechanism hypothesis, other than the dopamine hypothesis. Studies have revealed the possibility that functional abnormalities of the NMDAR play important roles in the pathophysiology/pathomechanism of schizophrenia. However, no antipsychotics derived from the glutamatergic hypothesis have yet been approved for the treatment of schizophrenia or treatment-resistant schizophrenia. Considering the increasing evidence supporting the potential pro-cognitive effects of glutamatergic agents and the lack of sufficient medications to treat the cognitive impairments associated with schizophrenia, these previous setbacks cannot preclude research into potential novel glutamate modulators. Given this background, to emphasize the importance of the dysfunction of the NMDAR in the pathomechanism and/or pathophysiology of schizophrenia, this review introduces the increasing findings on the functional abnormalities in glutamatergic transmission associated with the NMDAR.
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Affiliation(s)
- Ruri Okubo
- Department of Neuropsychiatry, Division of Neuroscience, Graduate School of Medicine, Mie University, Tsu 514-8507, Japan
| | - Motohiro Okada
- Department of Neuropsychiatry, Division of Neuroscience, Graduate School of Medicine, Mie University, Tsu 514-8507, Japan
| | - Eishi Motomura
- Department of Neuropsychiatry, Division of Neuroscience, Graduate School of Medicine, Mie University, Tsu 514-8507, Japan
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3
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Phone Myint SMM, Sun LY. L-serine: Neurological Implications and Therapeutic Potential. Biomedicines 2023; 11:2117. [PMID: 37626614 PMCID: PMC10452085 DOI: 10.3390/biomedicines11082117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 08/27/2023] Open
Abstract
L-serine is a non-essential amino acid that plays a vital role in protein synthesis, cell proliferation, development, and sphingolipid formation in the central nervous system. It exerts its effects through the activation of glycine receptors and upregulation of PPAR-γ, resulting in neurotransmitter synthesis, neuroprotection, and anti-inflammatory effects. L-serine shows potential as a protective agent in various neurological diseases and neurodegenerative disorders. Deficiency of L-serine and its downstream products has been linked to severe neurological deficits. Despite its crucial role, there is limited understanding of its mechanistic production and impact on glial and neuronal cells. Most of the focus has been on D-serine, the downstream product of L-serine, which has been implicated in a wide range of neurological diseases. However, L-serine is approved by FDA for supplemental use, while D-serine is not. Hence, it is imperative that we investigate the wider effects of L-serine, particularly in relation to the pathogenesis of several neurological deficits that, in turn, lead to diseases. This review aims to explore current knowledge surrounding L-serine and its potential as a treatment for various neurological diseases and neurodegenerative disorders.
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Affiliation(s)
| | - Liou Y. Sun
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35233, USA;
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4
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Park DK, Stein IS, Zito K. Ion flux-independent NMDA receptor signaling. Neuropharmacology 2022; 210:109019. [PMID: 35278420 DOI: 10.1016/j.neuropharm.2022.109019] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 02/23/2022] [Accepted: 02/24/2022] [Indexed: 01/01/2023]
Abstract
NMDA receptors play vital roles in a broad array of essential brain functions, from synaptic transmission and plasticity to learning and memory. Historically, the fundamental roles of NMDARs were attributed to their specialized properties of ion flux. More recently, it has become clear that NMDARs also signal in an ion flux-independent manner. Here, we review these non-ionotropic NMDAR signaling mechanisms that have been reported to contribute to a broad array of neuronal functions and dysfunctions including synaptic transmission and plasticity, cell death and survival, and neurological disorders.
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Affiliation(s)
- Deborah K Park
- Center for Neuroscience, University of California, Davis, CA, 95618, USA
| | - Ivar S Stein
- Center for Neuroscience, University of California, Davis, CA, 95618, USA
| | - Karen Zito
- Center for Neuroscience, University of California, Davis, CA, 95618, USA.
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5
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d-Amino Acids and pLG72 in Alzheimer's Disease and Schizophrenia. Int J Mol Sci 2021; 22:ijms222010917. [PMID: 34681579 PMCID: PMC8535920 DOI: 10.3390/ijms222010917] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/01/2021] [Accepted: 10/06/2021] [Indexed: 01/02/2023] Open
Abstract
Numerous studies over the last several years have shown that d-amino acids, especially d-serine, have been related to brain and neurological disorders. Acknowledged neurological functions of d-amino acids include neurotransmission and learning and memory functions through modulating N-methyl-d-aspartate type glutamate receptors (NMDARs). Aberrant d-amino acids level and polymorphisms of genes related to d-amino acids metabolism are associated with neurodegenerative brain conditions. This review summarizes the roles of d-amino acids and pLG72, also known as d-amino acid oxidase activator, on two neurodegenerative disorders, schizophrenia and Alzheimer’s disease (AD). The scope includes the changes in d-amino acids levels, gene polymorphisms of G72 genomics, and the role of pLG72 on NMDARs and mitochondria in schizophrenia and AD. The clinical diagnostic value of d-amino acids and pLG72 and the therapeutic importance are also reviewed.
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Navarro-Gonzalez C, Carceller H, Benito Vicente M, Serra I, Navarrete M, Domínguez-Canterla Y, Rodríguez-Prieto Á, González-Manteiga A, Fazzari P. Nrg1 haploinsufficiency alters inhibitory cortical circuits. Neurobiol Dis 2021; 157:105442. [PMID: 34246770 DOI: 10.1016/j.nbd.2021.105442] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 05/19/2021] [Accepted: 06/30/2021] [Indexed: 11/19/2022] Open
Abstract
Neuregulin 1 (NRG1) and its receptor ERBB4 are schizophrenia (SZ) risk genes that control the development of both excitatory and inhibitory cortical circuits. Most studies focused on the characterization ErbB4 deficient mice. However, ErbB4 deletion concurrently perturbs the signaling of Nrg1 and Neuregulin 3 (Nrg3), another ligand expressed in the cortex. In addition, NRG1 polymorphisms linked to SZ locate mainly in non-coding regions and they may partially reduce Nrg1 expression. Here, to study the relevance of Nrg1 partial loss-of-function in cortical circuits we characterized a recently developed haploinsufficient mouse model of Nrg1 (Nrg1tm1Lex). These mice display SZ-like behavioral deficits. The cellular and molecular underpinnings of the behavioral deficits in Nrg1tm1Lex mice remain to be established. With multiple approaches including Magnetic Resonance Spectroscopy (MRS), electrophysiology, quantitative imaging and molecular analysis we found that Nrg1 haploinsufficiency impairs the inhibitory cortical circuits. We observed changes in the expression of molecules involved in GABAergic neurotransmission, decreased density of Vglut1 excitatory buttons onto Parvalbumin interneurons and decreased frequency of spontaneous inhibitory postsynaptic currents. Moreover, we found a decreased number of Parvalbumin positive interneurons in the cortex and altered expression of Calretinin. Interestingly, we failed to detect other alterations in excitatory neurons that were previously reported in ErbB4 null mice suggesting that the Nrg1 haploinsufficiency does not entirely phenocopies ErbB4 deletions. Altogether, this study suggests that Nrg1 haploinsufficiency primarily affects the cortical inhibitory circuits in the cortex and provides new insights into the structural and molecular synaptic impairment caused by NRG1 hypofunction in a preclinical model of SZ.
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Affiliation(s)
- Carmen Navarro-Gonzalez
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Héctor Carceller
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Marina Benito Vicente
- Laboratorio Resonancia Magnética de Investigación, Hospital Nacional de Parapléjicos, Toledo, Spain.
| | - Irene Serra
- Consejo Superior de Investigaciones Científicas (CSIC), Instituto Cajal, Madrid, Spain.
| | - Marta Navarrete
- Consejo Superior de Investigaciones Científicas (CSIC), Instituto Cajal, Madrid, Spain.
| | - Yaiza Domínguez-Canterla
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Ángela Rodríguez-Prieto
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Ana González-Manteiga
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain.
| | - Pietro Fazzari
- Lab of Cortical Circuits in Health and Disease, CIPF Centro de Investigación Príncipe Felipe, Valencia, Spain; Consejo Superior de Investigaciones Científicas (CSIC), Centro de Biología Molecular Severo Ochoa, Madrid, Spain.
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7
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Prevalence and clinical demography of hyperhomocysteinemia in Han Chinese patients with schizophrenia. Eur Arch Psychiatry Clin Neurosci 2021; 271:759-765. [PMID: 32514603 DOI: 10.1007/s00406-020-01150-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/04/2020] [Indexed: 12/11/2022]
Abstract
Previous studies have shown that high homocysteine worsens the occurrence, symptoms, and prognosis of patients with schizophrenia. The purpose of this study was to evaluate the prevalence, clinical correlation, and demographic characteristics of hyperhomocysteinemia in Han Chinese schizophrenia patients. In this study, we enrolled 330 schizophrenia patients and 190 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the psychiatric symptoms of patients with schizophrenia. The plasma homocysteine level was measured by the enzyme cycle method and the concentration of homocysteine > 15 μmol/L was defined as hyperhomocysteinemia. The prevalence of hyperhomocysteinemia in Han Chinese schizophrenia patients and healthy controls was 55.05% and 26.98%, respectively. Schizophrenia patients with hyperhomocysteinemia had more male proportion, older age, higher smoking rate, lower HDL level, higher PANSS total score, and higher negative factor than those patients without hyperhomocysteinemia. Binary logical regression result showed that gender and age were the independent risk factors of hyperhomocysteinemia. Han Chinese patients with schizophrenia had high prevalence hyperhomocysteinemia than healthy controls, and elderly male patients have a higher risk of hyperhomocysteinemia. This study was registered in the China Clinical Trial Registration Center (chiCTR 1800017044).
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8
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Aguilar DD, Radzik LK, Schiffino FL, Folorunso OO, Zielinski MR, Coyle JT, Balu DT, McNally JM. Altered neural oscillations and behavior in a genetic mouse model of NMDA receptor hypofunction. Sci Rep 2021; 11:9031. [PMID: 33907230 PMCID: PMC8079688 DOI: 10.1038/s41598-021-88428-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 04/09/2021] [Indexed: 12/18/2022] Open
Abstract
Abnormalities in electroencephalographic (EEG) biomarkers occur in patients with schizophrenia and those clinically at high risk for transition to psychosis and are associated with cognitive impairment. Converging evidence suggests N-methyl-D-aspartate receptor (NMDAR) hypofunction plays a central role in the pathophysiology of schizophrenia and likely contributes to biomarker impairments. Thus, characterizing these biomarkers is of significant interest for early diagnosis of schizophrenia and development of novel treatments. We utilized in vivo EEG recordings and behavioral analyses to perform a battery of electrophysiological biomarkers in an established model of chronic NMDAR hypofunction, serine racemase knockout (SRKO) mice, and their wild-type littermates. SRKO mice displayed impairments in investigation-elicited gamma power that corresponded with reduced short-term social recognition and enhanced background (pre-investigation) gamma activity. Additionally, SRKO mice exhibited sensory gating impairments in both evoked-gamma power and event-related potential amplitude. However, other biomarkers including the auditory steady-state response, sleep spindles, and state-specific power spectral density were generally neurotypical. In conclusion, SRKO mice demonstrate how chronic NMDAR hypofunction contributes to deficits in certain translationally-relevant EEG biomarkers altered in schizophrenia. Importantly, our gamma band findings suggest an aberrant signal-to-noise ratio impairing cognition that occurs with NMDAR hypofunction, potentially tied to impaired task-dependent alteration in functional connectivity.
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Affiliation(s)
- David D Aguilar
- VA Boston Healthcare System, West Roxbury, MA, USA. .,Department of Psychiatry, Harvard Medical School, Boston, MA, USA.
| | - Leana K Radzik
- Department of Neuroscience, Stonehill College, Easton, MA, USA
| | - Felipe L Schiffino
- VA Boston Healthcare System, West Roxbury, MA, USA.,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Oluwarotimi O Folorunso
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.,Translational Psychiatry Laboratory, McLean Hospital, Belmont, MA, USA
| | - Mark R Zielinski
- VA Boston Healthcare System, West Roxbury, MA, USA.,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.,Laboratory of Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA, USA
| | - Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA.,Translational Psychiatry Laboratory, McLean Hospital, Belmont, MA, USA
| | - James M McNally
- VA Boston Healthcare System, West Roxbury, MA, USA.,Department of Psychiatry, Harvard Medical School, Boston, MA, USA
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9
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Coyle JT, Ruzicka WB, Balu DT. Fifty Years of Research on Schizophrenia: The Ascendance of the Glutamatergic Synapse. Am J Psychiatry 2020; 177:1119-1128. [PMID: 33256439 PMCID: PMC8011846 DOI: 10.1176/appi.ajp.2020.20101481] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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Winship IR, Dursun SM, Baker GB, Balista PA, Kandratavicius L, Maia-de-Oliveira JP, Hallak J, Howland JG. An Overview of Animal Models Related to Schizophrenia. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2019; 64:5-17. [PMID: 29742910 PMCID: PMC6364139 DOI: 10.1177/0706743718773728] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Schizophrenia is a heterogeneous psychiatric disorder that is poorly treated with current therapies. In this brief review, we provide an update regarding the use of animal models to study schizophrenia in an attempt to understand its aetiology and develop novel therapeutic strategies. Tremendous progress has been made developing and validating rodent models that replicate the aetiologies, brain pathologies, and behavioural abnormalities associated with schizophrenia in humans. Here, models are grouped into 3 categories-developmental, drug induced, and genetic-to reflect the heterogeneous risk factors associated with schizophrenia. Each of these models is associated with varied but overlapping pathophysiology, endophenotypes, behavioural abnormalities, and cognitive impairments. Studying schizophrenia using multiple models will permit an understanding of the core features of the disease, thereby facilitating preclinical research aimed at the development and validation of better pharmacotherapies to alter the progression of schizophrenia or alleviate its debilitating symptoms.
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Affiliation(s)
- Ian R Winship
- 1 Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta
| | - Serdar M Dursun
- 2 Department of Psychiatry, Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta.,3 National Institute of Science and Technology-Translational Science, Brazil
| | - Glen B Baker
- 2 Department of Psychiatry, Neurochemical Research Unit and Bebensee Schizophrenia Research Unit, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta.,3 National Institute of Science and Technology-Translational Science, Brazil
| | - Priscila A Balista
- 4 Department of Pharmacy, Centro Universitario das Faculdades Metropolitanas Unidas, São Paulo, Brazil
| | - Ludmyla Kandratavicius
- 5 Department of Neuroscience and Behavior, Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Joao Paulo Maia-de-Oliveira
- 3 National Institute of Science and Technology-Translational Science, Brazil.,6 Department of Clinical Medicine, Rio Grande do Norte Federal University, Natal, Brazil
| | - Jaime Hallak
- 3 National Institute of Science and Technology-Translational Science, Brazil.,5 Department of Neuroscience and Behavior, Faculty of Medicine of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil.,7 Department of Psychiatry (NRU), University of Alberta, Edmonton, Alberta
| | - John G Howland
- 8 Department of Physiology, University of Saskatchewan, Saskatoon, Saskatchewan
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Balu DT, Coyle JT. Altered CREB Binding to Activity-Dependent Genes in Serine Racemase Deficient Mice, a Mouse Model of Schizophrenia. ACS Chem Neurosci 2018; 9:2205-2209. [PMID: 29172439 DOI: 10.1021/acschemneuro.7b00404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
cAMP-response-element-binding protein (CREB) is a transcription factor ubiquitously expressed in the brain that regulates neuroplasticity by modulating gene expression. The influx of calcium through N-methyl-d-aspartate receptors (NMDARs) is a well-defined mechanism that leads to the increased expression of CREB-dependent genes, including brain derived neurotrophic factor (BDNF), microRNA-132, and activity-regulated cytoskeleton-associated protein (Arc). These molecules are implicated in the pathophysiology of schizophrenia. We previously demonstrated that serine racemase knockout (SR-/-) mice, which exhibit NMDAR hypofunction due to a lack of the forebrain NMDAR co-agonist d-serine, also have reduced expression of CREB-dependent genes in the hippocampus. Using chromatin immunoprecipitation, we show here that, in SR-/- mice, there is less CREB bound to the promoter regions of BDNF, microRNA-132, and Arc. These data suggest that NMDAR hypofunction in SR-/- mice leads to reduced CREB binding on known activity-dependent genes, in turn contributing to their reduced expression.
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Affiliation(s)
- Darrick T. Balu
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
- Translational Psychiatry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
| | - Joseph T. Coyle
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
- Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, Massachusetts 02478, United States
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12
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Guercio GD, Panizzutti R. Potential and Challenges for the Clinical Use of d-Serine As a Cognitive Enhancer. Front Psychiatry 2018; 9:14. [PMID: 29459833 PMCID: PMC5807334 DOI: 10.3389/fpsyt.2018.00014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/17/2018] [Indexed: 12/16/2022] Open
Abstract
After 25 years of its discovery in the rat brain, d-serine is a recognized modulator of synaptic plasticity and cognitive processes through its actions on the NMDA-glutamate receptor. Importantly, cognitive impairment is a core feature of conditions, such as schizophrenia, Alzheimer's disease, depression, and aging, and is associated to disturbances in NMDA-glutamate receptors. The d-serine pathway has been associated with cognitive deficits and these conditions, and, for this reason, d-serine signaling is subject of intense research to probe its role in aiding diagnosis and therapy. Nevertheless, this has not resulted in new therapies being incorporated into clinical practice. Therefore, in this review we will address many questions that need to be solved by future studies, regarding d-serine pharmacokinetics, possible side effects, other strategies to modulate its levels, and combination with other therapies to increase its efficacy.
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Affiliation(s)
- Gerson D. Guercio
- Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rogerio Panizzutti
- Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Global Brain Health Institute, Trinity College Dublin, Dublin, Ireland
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Coyle JT, Balu DT. The Role of Serine Racemase in the Pathophysiology of Brain Disorders. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 82:35-56. [PMID: 29413527 PMCID: PMC5821497 DOI: 10.1016/bs.apha.2017.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The N-methyl-d-aspartate receptor (NMDAR) is unique in requiring two agonists to bind simultaneously to open its cation channel: the neurotransmitter, glutamate, and the coagonists, glycine, or d-serine. The Snyder laboratory was the first to clone serine racemase (SR), the enzyme that synthesizes d-serine, and to localize it immunocytochemically. Our laboratory has focused on the role of d-serine in brain disorders. Silencing the expression of SR, a risk gene for schizophrenia (SCZ), in mice (SR-/-), results in a phenotype that closely resembles SCZ including: cortical atrophy, reduced dendritic spine density and complexity, downregulation of parvalbumin-positive cortical GABAergic neurons, and cognitive impairments. This pathology can be reversed by treatment of SR-/- mice with d-serine in adulthood. SR-/- mice also exhibit abnormal response toward abusable substances, such as stimulants. They show reduced behavioral sensitization to d-amphetamine, but fail to extinguish it. Place preference to cocaine is altered, and the hedonic response to it is profoundly impaired as assessed by intracranial self-stimulation. d-cycloserine, a partial agonist at the NMDAR glycine modulatory site, shows therapeutic benefit for treating pathologic anxiety in combination with behavioral therapies. Studies in vitro with cortical culture and in vivo with middle cerebral artery occlusion show that silencing SR provides substantial protection against ischemic neuronal death. Finally, the switch of SR expression from neurons to reactive astrocytes after closed head trauma accounts for the reduced in vivo neuroplasticity, electroencephalogram abnormalities, and cognitive impairments.
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Affiliation(s)
- Joseph T Coyle
- Harvard Medical School, Boston, MA, United States; McLean Hospital, Belmont, MA, United States.
| | - Darrick T Balu
- Harvard Medical School, Boston, MA, United States; McLean Hospital, Belmont, MA, United States
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14
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McLaughlin JP, Paris JJ, Mintzopoulos D, Hymel KA, Kim JK, Cirino TJ, Gillis TE, Eans SO, Vitaliano GD, Medina JM, Krapf RC, Stacy HM, Kaufman MJ. Conditional Human Immunodeficiency Virus Transactivator of Transcription Protein Expression Induces Depression-like Effects and Oxidative Stress. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017; 2:599-609. [PMID: 29057370 PMCID: PMC5648358 DOI: 10.1016/j.bpsc.2017.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND The prevalence of major depression in those with HIV/AIDS is substantially higher than in the general population. Mechanisms underlying this comorbidity are poorly understood. HIV-transactivator of transcription (Tat) protein, produced and excreted by HIV, could be involved. We determined whether conditional Tat protein expression in mice is sufficient to induce depression-like behaviors and oxidative stress. Further, as oxidative stress is associated with depression, we determined whether decreasing or increasing oxidative stress by administering methylsulfonylmethane (MSM) or diethylmaleate (DEM), respectively, altered depression-like behavior. METHODS GT-tg bigenic mice received intraperitoneal saline or doxycycline (Dox, 25-100 mg/kg/day) to induce Tat expression. G-tg mice, which do not express Tat protein, also received Dox. Depression-like behavior was assessed with the tail suspension test (TST) and the two-bottle saccharin/water consumption task. Reactive oxygen/nitrogen species (ROS/RNS) were assessed ex vivo. Medial frontal cortex (MFC) oxidative stress and temperature were measured in vivo with 9.4-Tesla proton magnetic resonance spectroscopy (MRS). RESULTS Tat expression increased TST immobility time in an exposure-dependent manner and reduced saccharin consumption. MSM decreased immobility time while DEM increased it in saline-treated GT-tg mice. Tat and MSM behavioral effects persisted for 28 days. Tat and DEM increased while MSM decreased ROS/RNS levels. Tat expression increased MFC glutathione levels and temperature. CONCLUSIONS Tat expression induced rapid and enduring depression-like behaviors and oxidative stress. Increasing/decreasing oxidative stress increased/decreased, respectively, depression-like behavior. Thus, Tat produced by HIV may contribute to the high depression prevalence among those with HIV. Further, mitigation of oxidative stress could reduce depression severity.
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Affiliation(s)
- Jay P. McLaughlin
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Jason J. Paris
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
- Virginia Commonwealth University, Department of Pharmacology & Toxicology, Richmond, VA 23298
| | - Dionyssios Mintzopoulos
- McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478
| | - Kristen A. Hymel
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Jae K. Kim
- McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478
| | - Thomas J. Cirino
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Timothy E. Gillis
- McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478
| | - Shainnel O. Eans
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Gordana D. Vitaliano
- McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478
| | - Jessica M. Medina
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Richard C. Krapf
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Heather M. Stacy
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL 32610
| | - Marc J. Kaufman
- McLean Imaging Center, Department of Psychiatry, McLean Hospital/Harvard Medical School, Belmont, MA 02478
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Nelson DL, Applegate GA, Beio ML, Graham DL, Berkowitz DB. Human serine racemase structure/activity relationship studies provide mechanistic insight and point to position 84 as a hot spot for β-elimination function. J Biol Chem 2017; 292:13986-14002. [PMID: 28696262 DOI: 10.1074/jbc.m117.777904] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/26/2017] [Indexed: 11/06/2022] Open
Abstract
There is currently great interest in human serine racemase, the enzyme responsible for producing the NMDA co-agonist d-serine. Reported correlation of d-serine levels with disorders including Alzheimer's disease, ALS, and ischemic brain damage (elevated d-serine) and schizophrenia (reduced d-serine) has further piqued this interest. Reported here is a structure/activity relationship study of position Ser84, the putative re-face base. In the most extreme case of functional reprogramming, the S84D mutant displays a dramatic reversal of β-elimination substrate specificity in favor of l-serine over the normally preferred l-serine-O-sulfate (∼1200-fold change in kcat/Km ratios) and l (l-THA; ∼5000-fold change in kcat/Km ratios) alternative substrates. On the other hand, the S84T (which performs l-Ser racemization activity), S84A (good kcat but high Km for l-THA elimination), and S84N mutants (nearly WT efficiency for l-Ser elimination) displayed intermediate activity, all showing a preference for the anionic substrates, but generally attenuated compared with the native enzyme. Inhibition studies with l-erythro-β-hydroxyaspartate follow this trend, with both WT serine racemase and the S84N mutant being competitively inhibited, with Ki = 31 ± 1.5 μm and 1.5 ± 0.1 mm, respectively, and the S84D being inert to inhibition. Computational modeling pointed to a key role for residue Arg-135 in binding and properly positioning the l-THA and l-serine-O-sulfate substrates and the l-erythro-β-hydroxyaspartate inhibitor. Examination of available sequence data suggests that Arg-135 may have originated for l-THA-like β-elimination function in earlier evolutionary variants, and examination of available structural data suggests that a Ser84-H2O-Lys114 hydrogen-bonding network in human serine racemase lowers the pKa of the Ser84re-face base.
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Affiliation(s)
- David L Nelson
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Greg A Applegate
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Matthew L Beio
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - Danielle L Graham
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588
| | - David B Berkowitz
- From the Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588.
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16
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Balu DT, Li Y, Takagi S, Presti KT, Ramikie TS, Rook JM, Jones CK, Lindsley CW, Conn PJ, Bolshakov VY, Coyle JT. An mGlu5-Positive Allosteric Modulator Rescues the Neuroplasticity Deficits in a Genetic Model of NMDA Receptor Hypofunction in Schizophrenia. Neuropsychopharmacology 2016; 41:2052-61. [PMID: 26741285 PMCID: PMC4908650 DOI: 10.1038/npp.2016.2] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/01/2015] [Accepted: 01/02/2016] [Indexed: 12/13/2022]
Abstract
There is substantial evidence that NMDA receptor (NMDAR) hypofunction contributes to the pathophysiology of schizophrenia (SCZ). A recent large-scale genome-wide association study identified serine racemase (SR), the enzyme that produces the NMDAR co-agonist D-serine, as a risk gene for SCZ. Serine racemase knockout (SR-/-) mice, which lack D-serine, exhibit many of the neurochemical and behavioral abnormalities observed in SCZ. Metabotropic glutamate receptor 5 (mGlu5)-positive allosteric modulators (PAMs) are currently being developed to treat cognitive dysfunction. We used in vitro electrophysiology to determine whether the mGlu5 PAM VU0409551 directly enhances NMDAR function in hippocampal slices from adult male SR-/- mice. We administered VU0409551 systemically for 5 days to adult male wild-type C57BL/6 animals to determine the optimal dose to test in SR-/- mice. We used western blot analyses and trace-fear conditioning to determine whether 5 days of VU0409551 treatment could reverse the neuroplasticity and learning deficits, respectively, in SR-/- mice. We show that VU0409551 enhances NMDAR function and rescues long-term potentiation in hippocampal slices obtained from SR-/- mice. Systemic treatment with VU0409551 (10 and 30 mg/kg) to wild-type mice causes a dose-dependent increase in the Akt/GS3Kα/β signaling pathway, which is reduced in SR-/- mice and in SCZ. Furthermore, the administration of VU0409551 to SR-/- mice reverses their deficits in several neuroplasticity signaling pathways and improves their contextual fear memory. These results support positive allosteric modulation of mGlu5, particularly with VU0409551, as a viable mechanism to reverse the deficits in NMDAR function, synaptic plasticity, and memory that are known to be impaired in SCZ.
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Affiliation(s)
- Darrick T Balu
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA,Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA, USA,Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA, Tel: +617 855 2329, Fax: +617 855 2705, E-mail:
| | - Yan Li
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Shunsuke Takagi
- Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA, USA,Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kendall Taylor Presti
- Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA, USA
| | - Teniel S Ramikie
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Jerri M Rook
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Carrie K Jones
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA,Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, Belmont, MA, USA
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Febo M, Foster TC. Preclinical Magnetic Resonance Imaging and Spectroscopy Studies of Memory, Aging, and Cognitive Decline. Front Aging Neurosci 2016; 8:158. [PMID: 27468264 PMCID: PMC4942756 DOI: 10.3389/fnagi.2016.00158] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 06/16/2016] [Indexed: 01/14/2023] Open
Abstract
Neuroimaging provides for non-invasive evaluation of brain structure and activity and has been employed to suggest possible mechanisms for cognitive aging in humans. However, these imaging procedures have limits in terms of defining cellular and molecular mechanisms. In contrast, investigations of cognitive aging in animal models have mostly utilized techniques that have offered insight on synaptic, cellular, genetic, and epigenetic mechanisms affecting memory. Studies employing magnetic resonance imaging and spectroscopy (MRI and MRS, respectively) in animal models have emerged as an integrative set of techniques bridging localized cellular/molecular phenomenon and broader in vivo neural network alterations. MRI methods are remarkably suited to longitudinal tracking of cognitive function over extended periods permitting examination of the trajectory of structural or activity related changes. Combined with molecular and electrophysiological tools to selectively drive activity within specific brain regions, recent studies have begun to unlock the meaning of fMRI signals in terms of the role of neural plasticity and types of neural activity that generate the signals. The techniques provide a unique opportunity to causally determine how memory-relevant synaptic activity is processed and how memories may be distributed or reconsolidated over time. The present review summarizes research employing animal MRI and MRS in the study of brain function, structure, and biochemistry, with a particular focus on age-related cognitive decline.
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Affiliation(s)
- Marcelo Febo
- Department of Psychiatry, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
| | - Thomas C Foster
- Department of Neuroscience, William L. and Evelyn F. McKnight Brain Institute, University of Florida Gainesville, FL, USA
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Ultimate Translation: Developing Therapeutics Targeting on N-Methyl-d-Aspartate Receptor. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 76:257-309. [PMID: 27288080 DOI: 10.1016/bs.apha.2016.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
N-Methyl-d-aspartate receptors (NMDARs) are broadly distributed in the central nervous system (CNS), where they mediate excitatory signaling. NMDAR-mediated neurotransmission (NMDARMN) is the molecular engine of learning, memory and cognition, which are the basis for high cortical function. NMDARMN is also critically involved in the development and plasticity of CNS. Due to its essential and critical role, either over- or under-activation of NMDARMN can contribute substantially to the development of CNS disorders. The involvement of NMDARMN has been demonstrated in a variety of CNS disorders, including schizophrenia, depression, posttraumatic stress disorder, aging, mild cognitive impairment and Alzheimer's dementia, amyotrophic lateral sclerosis, and anti-NMDAR encephalitis. Several targets to "correct" or "reset" the NMDARMN in these CNS disorders have been identified and confirmed. With analogy to aminergic treatments, these targets include the glycine/d-serine co-agonist site, channel ionophore, glycine transporter-1, and d-amino acid oxidase. It is still early days in terms of developing novel therapeutics targeting the NMDAR. However, agents modulating NMDARMN hold promise as the next generation of CNS therapeutics.
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The NMDA Receptor and Schizophrenia: From Pathophysiology to Treatment. ADVANCES IN PHARMACOLOGY 2016; 76:351-82. [PMID: 27288082 DOI: 10.1016/bs.apha.2016.01.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Schizophrenia is a severe mental illness that affects almost 1% of the population worldwide. Even though the etiology of schizophrenia is uncertain, it is believed to be a neurodevelopmental disorder that results from a combination of environmental insults and genetic vulnerabilities. Over the past 20 years, there has been a confluence of evidence from many research disciplines pointing to alterations in excitatory signaling, particularly involving hypofunction of the N-methyl-d-aspartate receptor (NMDAR), as a key contributor to the schizophrenia disease process. This review describes the structure-function relationship of the NMDAR channel and how the glycine modulatory site acts as an important regulator of its activity. In addition, this review highlights the genetic, pharmacologic, and biochemical evidence supporting the hypothesis that NMDAR hypofunction contributes to the pathophysiology of schizophrenia. Finally, this chapter highlights some of the most recent and promising pharmacological strategies that are designed to either, directly or indirectly, augment NMDAR function in an effort to treat the cognitive and negative symptoms of schizophrenia that are not helped by currently available medications.
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20
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Chiapponi C, Piras F, Piras F, Caltagirone C, Spalletta G. GABA System in Schizophrenia and Mood Disorders: A Mini Review on Third-Generation Imaging Studies. Front Psychiatry 2016; 7:61. [PMID: 27148090 PMCID: PMC4835487 DOI: 10.3389/fpsyt.2016.00061] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/29/2016] [Indexed: 11/18/2022] Open
Abstract
Third-generation neuroimaging research has been enriched by advances in magnetic resonance spectroscopy (MRS) measuring the concentration of important neurotrasmitters, such as the inhibitory amino acid GABA. Here, we performed a systematic mini-review on brain MRS studies measuring GABA concentration in patients affected by schizophrenia (SZ), bipolar disorder (BD), and major depressive disorder (MDD). We wondered whether multimodal investigations could overcome intrinsic technical limits of MRS giving a broader view of mental disorders pathogenesis. In SZ, unimodal studies gave mixed results, as increased, decreased, or unaltered GABA levels were reported depending on region, disease phase, and treatment. Conversely, multimodal results showed reduced level of glutamate, but not of GABA, in patients mirrored by in vitro biochemical findings revealing hippocampal reduction in glutamate signaling in SZ, and no deficits in GABA synthesis. Moreover, a mouse model confirmed the unique pathological characteristic of glutamate function in SZ. Unimodal studies in BD revealed again, inconsistent results, while no multimodal investigations including MRS on GABA exist. In MDD, unimodal studies could not differentiate patients from controls nor characterize high-risk subjects and remitted patients. However, a multimodal study combining functional magnetic resonance imaging and MRS revealed that cingulate cortex activity is related to glutamate, N-acetylaspartate levels and anhedonia in patients, and to GABA concentration in healthy subjects, improving the distinction between MDD and physiology. Overall, our results show that unimodal studies do not indicate GABA as a biomarker for the psychiatric disorders considered. Conversely, multimodal studies can widen the understanding of the link between psychopathology, genetics, neuroanatomy, and functional-biochemical brain activity in mental disorders. Although scarce, multimodal approaches seem promising for moving from GABA MRS unimodal-descriptive to causal level, and for integrating GABA results into a more comprehensive interpretation of mental disorder pathophysiology.
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Affiliation(s)
- Chiara Chiapponi
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy; Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Federica Piras
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation , Rome , Italy
| | - Fabrizio Piras
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy; Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy
| | - Carlo Caltagirone
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy; Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Gianfranco Spalletta
- Neuropsychiatry Laboratory, IRCCS Santa Lucia Foundation, Rome, Italy; Menninger Department of Psychiatry and Behavioral Sciences, Beth K. and Stuart C. Yudofsky Division of Neuropsychiatry, Baylor College of Medicine, Houston, TX, USA
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21
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Mintzopoulos D, Gillis TE, Robertson HR, Dalia T, Feng G, Rauch SL, Kaufman MJ. Striatal magnetic resonance spectroscopy abnormalities in young adult SAPAP3 knockout mice. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2016; 1:39-48. [PMID: 26858992 PMCID: PMC4742338 DOI: 10.1016/j.bpsc.2015.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Obsessive compulsive disorder (OCD) is a debilitating condition with lifetime prevalence of 1-3%. OCD typically arises in youth but delays in diagnosis impede optimal treatment and developmental studies of the disorder. Research using genetically modified rodents may provide models of etiology that enable earlier detection and intervention. The SAPAP3 knockout (KO) transgenic mouse was developed as an animal model of OCD and related disorders (OCRD). KO mice exhibit compulsive self-grooming behavior analogous to behaviors found in people with OCRD. Striatal hyperactivity has been reported in these mice and in humans with OCD. METHODS Striatal and medial frontal cortex 9.4 Tesla proton spectra were acquired from young adult SAPAP3 KO and wild-type control mice to determine whether KO mice have metabolic and neurochemical abnormalities. RESULTS Young adult KO mice had lower striatal lactate (P=0.006) and glutathione (P=0.039) levels. Among all mice, striatal lactate and glutathione levels were associated (R=0.73, P=0.007). We found no group differences in medial frontal cortex metabolites. At the age range studied, only 1 of 8 KO mice had skin lesions indicative of severe compulsive grooming. CONCLUSION Young adult SAPAP3 KO mice have striatal but not medial frontal cortex MRS abnormalities that may reflect striatal hypermetabolism accompanied by oxidative stress. These abnormalities typically preceded the onset of severe compulsive grooming. Our findings are consistent with striatal hypermetabolism in OCD. Together, these results suggest that striatal MRS measures of lactate or glutathione might be useful biomarkers for early detection of risk for developing compulsive behavior disorders.
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de la Fuente-Sandoval C, Reyes-Madrigal F, Mao X, León-Ortiz P, Rodríguez-Mayoral O, Solís-Vivanco R, Favila R, Graff-Guerrero A, Shungu DC. Cortico-Striatal GABAergic and Glutamatergic Dysregulations in Subjects at Ultra-High Risk for Psychosis Investigated with Proton Magnetic Resonance Spectroscopy. Int J Neuropsychopharmacol 2015; 19:pyv105. [PMID: 26364273 PMCID: PMC4815472 DOI: 10.1093/ijnp/pyv105] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 09/06/2015] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Dysregulations of the major inhibitory and excitatory amino neurotransmitter systems of γ-aminobutyric acid and glutamate, respectively, have been described in patients with schizophrenia. However, it is unclear whether these abnormalities are present in subjects at ultra-high risk for psychosis. METHODS Twenty-three antipsychotic naïve subjects at ultra-high risk and 24 healthy control subjects, matched for age, sex, handedness, cigarette smoking, and parental education, underwent proton magnetic resonance spectroscopy scans in the dorsal caudate bilaterally and the medial prefrontal cortex at 3T. Levels of γ-aminobutyric acid and of the combined resonance of glutamate and glutamine (Glx) were obtained using the standard J-editing technique and expressed as peak area ratios relative to the synchronously acquired unsuppressed voxel water signal. RESULTS Higher levels of γ-aminobutyric acid (P<.001) and Glx (P=.007) were found in the dorsal caudate of the subjects at ultra-high risk than in the healthy controls. In the medial prefrontal cortex, likewise, both γ-aminobutyric acid (P=.03) and Glx (P=.006) levels were higher in the ultra-high risk group than in the healthy controls. No group differences were found for any of the other metabolites (N-acetylaspartate, total choline, or total creatine) in the 2 regions of interest. CONCLUSIONS This study presents the first evidence of abnormal elevations, in subjects at ultra-high risk, of γ-aminobutyric acid and Glx in 2 brain regions that have been implicated in the pathophysiology of psychosis, warranting longitudinal studies to assess whether these neurotransmitter abnormalities can serve as noninvasive biomarkers of conversion risk to psychosis as well as of illness progression and treatment response.
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Affiliation(s)
- Camilo de la Fuente-Sandoval
- Laboratory of Experimental Psychiatry (Drs de la Fuente-Sandoval, Reyes-Madrigal, and León-Ortiz), Neuropsychiatry Department (Dr de la Fuente-Sandoval), Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico; Department of Radiology, Weill Cornell Medical College, New York, NY (Ms Mao and Dr Shungu); Department of Education, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico (Dr León-Ortiz); Early Psychosis Intervention Department, Hospital Fray Bernardino Alvarez, Mexico City, Mexico (Dr Rodríguez-Mayoral); Palliative Care Unit, Instituto Nacional de Cancerología, Mexico City, Mexico (Dr Rodríguez-Mayoral); Laboratory of Neuropsychology, Instituto Nacional de Neurología y Neurocirugía, Mexico City, Mexico (Dr Solís-Vivanco); MR Advanced Applications, GE Healthcare, Mexico City, Mexico (Mr Favila); Multimodal Neuroimaging Schizophrenia Group, Research Imaging Centre, and Geriatric Mental Health Program at Centre for Addiction and Mental Health and Department of Psychiatry, University of Toronto, Canada (Dr Graff-Guerrero).
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Koyama Y. Functional alterations of astrocytes in mental disorders: pharmacological significance as a drug target. Front Cell Neurosci 2015. [PMID: 26217185 PMCID: PMC4491615 DOI: 10.3389/fncel.2015.00261] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Astrocytes play an essential role in supporting brain functions in physiological and pathological states. Modulation of their pathophysiological responses have beneficial actions on nerve tissue injured by brain insults and neurodegenerative diseases, therefore astrocytes are recognized as promising targets for neuroprotective drugs. Recent investigations have identified several astrocytic mechanisms for modulating synaptic transmission and neural plasticity. These include altered expression of transporters for neurotransmitters, release of gliotransmitters and neurotrophic factors, and intercellular communication through gap junctions. Investigation of patients with mental disorders shows morphological and functional alterations in astrocytes. According to these observations, manipulation of astrocytic function by gene mutation and pharmacological tools reproduce mental disorder-like behavior in experimental animals. Some drugs clinically used for mental disorders affect astrocyte function. As experimental evidence shows their role in the pathogenesis of mental disorders, astrocytes have gained much attention as drug targets for mental disorders. In this paper, I review functional alterations of astrocytes in several mental disorders including schizophrenia, mood disorder, drug dependence, and neurodevelopmental disorders. The pharmacological significance of astrocytes in mental disorders is also discussed.
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Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University Tondabayashi, Osaka, Japan
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Puhl MD, Berg AR, Bechtholt AJ, Coyle JT. Availability of N-Methyl-d-Aspartate Receptor Coagonists Affects Cocaine-Induced Conditioned Place Preference and Locomotor Sensitization: Implications for Comorbid Schizophrenia and Substance Abuse. J Pharmacol Exp Ther 2015; 353:465-70. [PMID: 25788713 DOI: 10.1124/jpet.115.223099] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/09/2015] [Indexed: 11/22/2022] Open
Abstract
Schizophrenia is associated with high prevalence of substance abuse. Recent research suggests that dysregulation of N-methyl-d-aspartate receptor (NMDAR) function may play a role in the pathophysiology of both schizophrenia and drug addiction, and thus, may account for this high comorbidity. Our laboratory has developed two transgenic mouse lines that exhibit contrasting NMDAR activity based on the availability of the glycine modulatory site (GMS) agonists d-serine and glycine. Glycine transporter 1 knockdowns (GlyT1(+/-)) exhibit NMDAR hyperfunction, whereas serine racemase knockouts (SR(-/-)) exhibit NMDAR hypofunction. We characterized the behavior of these lines in a cocaine-induced (20 mg/kg) conditioned place preference (CPP) and locomotor sensitization paradigm. Compared with wild-type mice, GlyT1(+/-) mice displayed hastened extinction of CPP and robust cocaine-induced reinstatement. SR(-/-) mice appeared to immediately "forget" the learned preference, because they did not exhibit cocaine-induced reinstatement and also displayed attenuated locomotor sensitization. Treatment of GlyT1(+/-) mice with gavestinel (10 mg/kg on day 1; 5 mg/kg on days 2-17), a GMS antagonist, attenuated cocaine-induced CPP and caused them to immediately "forget" the learned preference. Treatment of SR(-/-) mice with d-serine (300 mg/kg on day 1; 150 mg/kg on days 2-17) to normalize brain levels caused them to avoid the cocaine-paired side of the chamber during extinction. These results highlight NMDAR dysfunction as a possible neural mechanism underlying comorbid schizophrenia and substance abuse. Also, these findings suggest drugs that directly or indirectly activate the NMDAR GMS could be an effective treatment of cocaine abuse.
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Affiliation(s)
- Matthew D Puhl
- Department of Psychiatry, Harvard Medical School (M.D.P., A.R.B., A.J.B., J.T.C.), and Laboratory for Psychiatric and Molecular Neuroscience (M.D.P., A.R.B., J.T.C.) and Behavioral Genetics Laboratory (A.J.B.), McLean Hospital, Belmont, Massachusetts
| | - Alexandra R Berg
- Department of Psychiatry, Harvard Medical School (M.D.P., A.R.B., A.J.B., J.T.C.), and Laboratory for Psychiatric and Molecular Neuroscience (M.D.P., A.R.B., J.T.C.) and Behavioral Genetics Laboratory (A.J.B.), McLean Hospital, Belmont, Massachusetts
| | - Anita J Bechtholt
- Department of Psychiatry, Harvard Medical School (M.D.P., A.R.B., A.J.B., J.T.C.), and Laboratory for Psychiatric and Molecular Neuroscience (M.D.P., A.R.B., J.T.C.) and Behavioral Genetics Laboratory (A.J.B.), McLean Hospital, Belmont, Massachusetts
| | - Joseph T Coyle
- Department of Psychiatry, Harvard Medical School (M.D.P., A.R.B., A.J.B., J.T.C.), and Laboratory for Psychiatric and Molecular Neuroscience (M.D.P., A.R.B., J.T.C.) and Behavioral Genetics Laboratory (A.J.B.), McLean Hospital, Belmont, Massachusetts
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Takagi S, Balu DT, Coyle JT. Subchronic pharmacological and chronic genetic NMDA receptor hypofunction differentially regulate the Akt signaling pathway and Arc expression in juvenile and adult mice. Schizophr Res 2015; 162:216-21. [PMID: 25592804 PMCID: PMC4339465 DOI: 10.1016/j.schres.2014.12.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/18/2014] [Accepted: 12/22/2014] [Indexed: 10/24/2022]
Abstract
NMDA receptor (NMDAR) hypofunction is a compelling hypothesis for the pathophysiology of schizophrenia, because in part, NMDAR antagonists cause symptoms in healthy adult subjects that resemble schizophrenia. Therefore, NMDAR antagonists have been used as a method to induce NMDAR hypofunction in animals as a pharmacological model of schizophrenia. Serine racemase-null mutant (SR-/-) mice display constitutive NMDAR hypofunction due to the lack of d-serine. SR-/- mice have deficits in tropomyosin-related kinase receptor (TrkB)/Akt signaling and activity regulated cytoskeletal protein (Arc) expression, which mirror what is observed in schizophrenia. Thus, we analyzed these signaling pathways in MK801 sub-chronically (0.15mg/kg; 5days) treated adult wild-type mice. We found that in contrast to SR-/- mice, the activated states of downstream signaling molecules, but not TrkB, increased in MK801 treated mice. Furthermore, there is an age-dependent change in the behavioral reaction of people to NMDAR antagonists. We therefore administered the same dosing regimen of MK801 to juvenile mice and compared them to juvenile SR-/- mice. Our findings demonstrate that pharmacological NMDAR antagonism has different effects on TrkB/Akt signaling than genetically-induced NMDAR hypofunction. Given the phenotypic disparity between the MK801 model and schizophrenia, our results suggest that SR-/- mice more accurately reflect NMDAR hypofunction in schizophrenia.
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Affiliation(s)
- Shunsuke Takagi
- Department of Psychiatry and Behavioral Sciences, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA.
| | - Darrick T. Balu
- Department of Psychiatry, Harvard Medical School, 25 Shattuck Street Boston, Boston, MA, USA 02115
,Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, 115 Mill Street, Belmont, MA, USA 02478
| | - Joseph T. Coyle
- Department of Psychiatry, Harvard Medical School, 25 Shattuck Street Boston, Boston, MA, USA 02115
,Laboratory for Psychiatric and Molecular Neuroscience, McLean Hospital, 115 Mill Street, Belmont, MA, USA 02478
,Corresponding author: Joseph T. Coyle, M.D., Harvard Medical School, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA. , Tel.: 617-855-2101, Fax: 617-855-2705
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