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Chen M, Ma S, Liu H, Dong Y, Tang J, Ni Z, Tan Y, Duan C, Li H, Huang H, Li Y, Cao X, Lingle CJ, Yang Y, Hu H. Brain region-specific action of ketamine as a rapid antidepressant. Science 2024; 385:eado7010. [PMID: 39116252 DOI: 10.1126/science.ado7010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Accepted: 06/04/2024] [Indexed: 08/10/2024]
Abstract
Ketamine has been found to have rapid and potent antidepressant activity. However, despite the ubiquitous brain expression of its molecular target, the N-methyl-d-aspartate receptor (NMDAR), it was not clear whether there is a selective, primary site for ketamine's antidepressant action. We found that ketamine injection in depressive-like mice specifically blocks NMDARs in lateral habenular (LHb) neurons, but not in hippocampal pyramidal neurons. This regional specificity depended on the use-dependent nature of ketamine as a channel blocker, local neural activity, and the extrasynaptic reservoir pool size of NMDARs. Activating hippocampal or inactivating LHb neurons swapped their ketamine sensitivity. Conditional knockout of NMDARs in the LHb occluded ketamine's antidepressant effects and blocked the systemic ketamine-induced elevation of serotonin and brain-derived neurotrophic factor in the hippocampus. This distinction of the primary versus secondary brain target(s) of ketamine should help with the design of more precise and efficient antidepressant treatments.
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Affiliation(s)
- Min Chen
- Department of Affiliated Mental Health Center & Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Shuangshuang Ma
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
- The Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University School of Medicine, Zhejiang University, Yiwu 322000, China
| | - Hanxiao Liu
- Department of Affiliated Mental Health Center & Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Yiyan Dong
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Jingxiang Tang
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Zheyi Ni
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Yi Tan
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Chenchi Duan
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai 200433, China
| | - Hui Li
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Hefeng Huang
- The Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University School of Medicine, Zhejiang University, Yiwu 322000, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, New Cornerstone Science Laboratory, School of Life Sciences, Peking University, Beijing 100871, China
| | - Xiaohua Cao
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, School of Life Science, East China Normal University, Shanghai 200062, China
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63105, USA
| | - Yan Yang
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
| | - Hailan Hu
- Department of Affiliated Mental Health Center & Hangzhou Seventh People's Hospital and School of Brain Science and Brain Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
- Liangzhu Laboratory, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, State Key Laboratory of Brain-Machine Intelligence, New Cornerstone Science Laboratory, Zhejiang University, Hangzhou 311121, China
- The Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University School of Medicine, Zhejiang University, Yiwu 322000, China
- Institute of Fundamental and Transdisciplinary Research, Zhejiang University, Hangzhou 311121, China
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2
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Yegla B, Rani A, Kumar A. Viral vector-mediated upregulation of serine racemase expression in medial prefrontal cortex improves learning and synaptic function in middle age rats. Aging (Albany NY) 2023; 15:2433-2449. [PMID: 37052995 PMCID: PMC10120901 DOI: 10.18632/aging.204652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 04/03/2023] [Indexed: 04/14/2023]
Abstract
An age-associated decrease in N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic function contributes to impaired synaptic plasticity and is associated with cognitive impairments. Levels of serine racemase (SR), an enzyme that synthesizes D-serine, an NMDAR co-agonist, decline with age. Thus, enhancing NMDAR function via increased SR expression in middle age, when subtle declines in cognition emerge, was predicted to enhance performance on a prefrontal cortex-mediated task sensitive to aging. Middle-aged (~12 mo) male Fischer-344 rats were injected bilaterally in the medial prefrontal cortex (mPFC) with viral vector (LV), SR (LV-SR) or control (LV-GFP). Rats were trained on the operant attentional set-shift task (AST) to examine cognitive flexibility and attentional function. LV-SR rats exhibited a faster rate of learning compared to controls during visual discrimination of the AST. Extradimensional set shifting and reversal were not impacted. Immunohistochemical analyses demonstrated that LV-SR significantly increased SR expression in the mPFC. Electrophysiological characterization of synaptic transmission in the mPFC slices obtained from LV-GFP and LV-SR animals indicated a significant increase in isolated NMDAR-mediated synaptic responses in LV-SR slices. Thus, results of the current study demonstrated that prefrontal SR upregulation in middle age rats can improve learning of task contingencies for visual discrimination and increase glutamatergic synaptic transmission, including NMDAR activity.
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Affiliation(s)
- Brittney Yegla
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Asha Rani
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
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de Bartolomeis A, Vellucci L, Austin MC, De Simone G, Barone A. Rational and Translational Implications of D-Amino Acids for Treatment-Resistant Schizophrenia: From Neurobiology to the Clinics. Biomolecules 2022; 12:biom12070909. [PMID: 35883465 PMCID: PMC9312470 DOI: 10.3390/biom12070909] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 06/25/2022] [Accepted: 06/26/2022] [Indexed: 12/13/2022] Open
Abstract
Schizophrenia has been conceptualized as a neurodevelopmental disorder with synaptic alterations and aberrant cortical–subcortical connections. Antipsychotics are the mainstay of schizophrenia treatment and nearly all share the common feature of dopamine D2 receptor occupancy, whereas glutamatergic abnormalities are not targeted by the presently available therapies. D-amino acids, acting as N-methyl-D-aspartate receptor (NMDAR) modulators, have emerged in the last few years as a potential augmentation strategy in those cases of schizophrenia that do not respond well to antipsychotics, a condition defined as treatment-resistant schizophrenia (TRS), affecting almost 30–40% of patients, and characterized by serious cognitive deficits and functional impairment. In the present systematic review, we address with a direct and reverse translational perspective the efficacy of D-amino acids, including D-serine, D-aspartate, and D-alanine, in poor responders. The impact of these molecules on the synaptic architecture is also considered in the light of dendritic spine changes reported in schizophrenia and antipsychotics’ effect on postsynaptic density proteins. Moreover, we describe compounds targeting D-amino acid oxidase and D-aspartate oxidase enzymes. Finally, other drugs acting at NMDAR and proxy of D-amino acids function, such as D-cycloserine, sarcosine, and glycine, are considered in the light of the clinical burden of TRS, together with other emerging molecules.
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Affiliation(s)
- Andrea de Bartolomeis
- Laboratory of Translational and Molecular Psychiatry and Unit of Treatment-Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, 80131 Naples, Italy; (L.V.); (G.D.S.); (A.B.)
- Correspondence: ; Tel.: +39-081-7463673 or +39-081-7463884 or +39-3662745592; Fax: +39-081-7462644
| | - Licia Vellucci
- Laboratory of Translational and Molecular Psychiatry and Unit of Treatment-Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, 80131 Naples, Italy; (L.V.); (G.D.S.); (A.B.)
| | - Mark C. Austin
- Clinical Psychopharmacology Program, College of Pharmacy, Idaho State University, Pocatello, ID 83209, USA;
| | - Giuseppe De Simone
- Laboratory of Translational and Molecular Psychiatry and Unit of Treatment-Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, 80131 Naples, Italy; (L.V.); (G.D.S.); (A.B.)
| | - Annarita Barone
- Laboratory of Translational and Molecular Psychiatry and Unit of Treatment-Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, 80131 Naples, Italy; (L.V.); (G.D.S.); (A.B.)
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Nagy LV, Bali ZK, Kapus G, Pelsőczi P, Farkas B, Lendvai B, Lévay G, Hernádi I. Converging Evidence on D-Amino Acid Oxidase-Dependent Enhancement of Hippocampal Firing Activity and Passive Avoidance Learning in Rats. Int J Neuropsychopharmacol 2020; 24:434-445. [PMID: 33305805 PMCID: PMC8130201 DOI: 10.1093/ijnp/pyaa095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND N-methyl-D-aspartate (NMDA) receptor activation requires the binding of a co-agonist on the glycine-binding site. D-serine is the main endogenous co-agonist of NMDA receptors, and its availability significantly depends on the activity of the metabolic enzyme D-amino acid oxidase (DAAO). Inhibition of DAAO increases the brain levels of D-serine and modulates a variety of physiological functions, including cognitive behavior. METHODS Here, we examined the effects of a novel 4-hydroxypyridazin-3(2H)-one derivative DAAO inhibitor, Compound 30 (CPD30), on passive avoidance learning and on neuronal firing activity in rats. RESULTS D-serine administration was applied as reference, which increased cognitive performance and enhanced hippocampal firing activity and responsiveness to NMDA after both local and systemic application. Similarly to D-serine, CPD30 (0.1 mg/kg) effectively reversed MK-801-induced memory impairment in the passive avoidance test. Furthermore, local iontophoretic application of CPD30 in the vicinity of hippocampal pyramidal neurons significantly increased firing rate and enhanced their responses to locally applied NMDA. CPD30 also enhanced hippocampal firing activity after systemic administration. In 0.1- to 1.0-mg/kg doses, CPD30 increased spontaneous and NMDA-evoked firing activity of the neurons. Effects of CPD30 on NMDA responsiveness emerged faster (at 10 minutes post-injection) when a 1.0-mg/kg dose was applied compared with the onset of the effects of 0.1 mg/kg CPD30 (at 30 minutes post-injection). CONCLUSIONS The present results confirm that the inhibition of DAAO enzyme is an effective strategy for cognitive enhancement. Our findings further facilitate the understanding of the cellular mechanisms underlying the behavioral effects of DAAO inhibition in the mammalian brain.
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Affiliation(s)
- Lili Veronika Nagy
- Department of Experimental Zoology and Neurobiology, Faculty of Sciences, University of Pécs, Pécs, Hungary,Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary
| | - Zsolt Kristóf Bali
- Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary,Grastyán Translational Research Center, University of Pécs, Pécs, Hungary,Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary,Correspondence: Zsolt Kristóf Bali, PhD, Translational Neuroscience Research Group, Grastyán Translational Research Center, 6 Ifjúság út, H-7624, Pécs, Hungary ()
| | - Gábor Kapus
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Péter Pelsőczi
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Bence Farkas
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - Balázs Lendvai
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary
| | - György Lévay
- Pharmacological and Drug Safety Research, Gedeon Richter Plc, Budapest, Hungary,Department of Morphology and Physiology, Faculty of Health Sciences, Semmelweis University, Budapest, Hungary
| | - István Hernádi
- Department of Experimental Zoology and Neurobiology, Faculty of Sciences, University of Pécs, Pécs, Hungary,Szentágothai Research Center, Center for Neuroscience, University of Pécs, Pécs, Hungary,Grastyán Translational Research Center, University of Pécs, Pécs, Hungary,Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
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5
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Crosta CM, Hernandez K, Bhattiprolu AK, Fu AY, Moore JC, Clarke SG, Dudzinski NR, Brzustowicz LM, Paradiso KG, Firestein BL. Characterization hiPSC-derived neural progenitor cells and neurons to investigate the role of NOS1AP isoforms in human neuron dendritogenesis. Mol Cell Neurosci 2020; 109:103562. [PMID: 32987141 PMCID: PMC7736313 DOI: 10.1016/j.mcn.2020.103562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/02/2020] [Accepted: 09/22/2020] [Indexed: 01/30/2023] Open
Abstract
Abnormal dendritic arbor development has been implicated in a number of neurodevelopmental disorders, such as autism and Rett syndrome, and the neuropsychiatric disorder schizophrenia. Postmortem brain samples from subjects with schizophrenia show elevated levels of NOS1AP in the dorsolateral prefrontal cortex, a region of the brain associated with cognitive function. We previously reported that the long isoform of NOS1AP (NOS1AP-L), but not the short isoform (NOS1AP-S), negatively regulates dendrite branching in rat hippocampal neurons. To investigate the role that NOS1AP isoforms play in human dendritic arbor development, we adapted methods to generate human neural progenitor cells and neurons using induced pluripotent stem cell (iPSC) technology. We found that increased protein levels of either NOS1AP-L or NOS1AP-S decrease dendrite branching in human neurons at the developmental time point when primary and secondary branching actively occurs. Next, we tested whether pharmacological agents can decrease the expression of NOS1AP isoforms. Treatment of human iPSC-derived neurons with d-serine, but not clozapine, haloperidol, fluphenazine, or GLYX-13, results in a reduction in endogenous NOS1AP-L, but not NOS1AP-S, protein expression; however, d-serine treatment does not reverse decreases in dendrite number mediated by overexpression of NOS1AP isoforms. In summary, we demonstrate how an in vitro model of human neuronal development can help in understanding the etiology of schizophrenia and can also be used as a platform to screen drugs for patients.
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Affiliation(s)
- Christen M Crosta
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Neurosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Kristina Hernandez
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Atul K Bhattiprolu
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Allen Y Fu
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Jennifer C Moore
- Department of Genetics, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854-8082, USA
| | - Stephen G Clarke
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Natasha R Dudzinski
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Linda M Brzustowicz
- Department of Genetics, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854-8082, USA
| | - Kenneth G Paradiso
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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Brown KA, Filipov NM, Wagner JJ. Dorsoventral-Specific Effects of Nerve Agent Surrogate Diisopropylfluorophosphate on Synaptic Transmission in the Mouse Hippocampus. J Pharmacol Exp Ther 2020; 373:10-23. [DOI: 10.1124/jpet.119.263053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/16/2019] [Indexed: 11/22/2022] Open
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de Bartolomeis A, Manchia M, Marmo F, Vellucci L, Iasevoli F, Barone A. Glycine Signaling in the Framework of Dopamine-Glutamate Interaction and Postsynaptic Density. Implications for Treatment-Resistant Schizophrenia. Front Psychiatry 2020; 11:369. [PMID: 32477178 PMCID: PMC7240307 DOI: 10.3389/fpsyt.2020.00369] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/14/2020] [Indexed: 12/14/2022] Open
Abstract
Treatment-resistant schizophrenia (TRS) or suboptimal response to antipsychotics affects almost 30% of schizophrenia (SCZ) patients, and it is a relevant clinical issue with significant impact on the functional outcome and on the global burden of disease. Among putative novel treatments, glycine-centered therapeutics (i.e. sarcosine, glycine itself, D-Serine, and bitopertin) have been proposed, based on a strong preclinical rationale with, however, mixed clinical results. Therefore, a better appraisal of glycine interaction with the other major players of SCZ pathophysiology and specifically in the framework of dopamine - glutamate interactions is warranted. New methodological approaches at cutting edge of technology and drug discovery have been applied to study the role of glycine in glutamate signaling, both at presynaptic and post-synaptic level and have been instrumental for unveiling the role of glycine in dopamine-glutamate interaction. Glycine is a non-essential amino acid that plays a critical role in both inhibitory and excitatory neurotransmission. In caudal areas of central nervous system (CNS), such as spinal cord and brainstem, glycine acts as a powerful inhibitory neurotransmitter through binding to its receptor, i.e. the Glycine Receptor (GlyR). However, glycine also works as a co-agonist of the N-Methyl-D-Aspartate receptor (NMDAR) in excitatory glutamatergic neurotransmission. Glycine concentration in the synaptic cleft is finely tuned by glycine transporters, i.e. GlyT1 and GlyT2, that regulate the neurotransmitter's reuptake, with the first considered a highly potential target for psychosis therapy. Reciprocal regulation of dopamine and glycine in forebrain, glycine modulation of glutamate, glycine signaling interaction with postsynaptic density proteins at glutamatergic synapse, and human genetics of glycinergic pathways in SCZ are tackled in order to highlight the exploitation of this neurotransmitters and related molecules in SCZ and TRS.
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Affiliation(s)
- Andrea de Bartolomeis
- Laboratory of Molecular Psychiatry and Translational Psychiatry, Unit of Treatment Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Science and Odontostomatology, University School of Medicine of Napoli Federico II, Naples, Italy
| | - Mirko Manchia
- Section of Psychiatry, Department of Medical Science and Public Health, University of Cagliari, Cagliari, Italy.,Department of Pharmacology, Dalhousie University, Halifax, NS, Canada
| | - Federica Marmo
- Laboratory of Molecular Psychiatry and Translational Psychiatry, Unit of Treatment Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Science and Odontostomatology, University School of Medicine of Napoli Federico II, Naples, Italy
| | - Licia Vellucci
- Laboratory of Molecular Psychiatry and Translational Psychiatry, Unit of Treatment Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Science and Odontostomatology, University School of Medicine of Napoli Federico II, Naples, Italy
| | - Felice Iasevoli
- Laboratory of Molecular Psychiatry and Translational Psychiatry, Unit of Treatment Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Science and Odontostomatology, University School of Medicine of Napoli Federico II, Naples, Italy
| | - Annarita Barone
- Laboratory of Molecular Psychiatry and Translational Psychiatry, Unit of Treatment Resistant Psychosis, Section of Psychiatry, Department of Neuroscience, Reproductive Science and Odontostomatology, University School of Medicine of Napoli Federico II, Naples, Italy
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Bolton AD, Constantine-Paton M. Synaptic Effects of Dopamine Breakdown and Their Relation to Schizophrenia-Linked Working Memory Deficits. Front Synaptic Neurosci 2018; 10:16. [PMID: 29950984 PMCID: PMC6008544 DOI: 10.3389/fnsyn.2018.00016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/23/2018] [Indexed: 12/18/2022] Open
Abstract
Working memory is the ability to hold information "online" over a time delay in order to perform a task. This kind of memory is encoded in the brain by persistent neural activity that outlasts the presentation of a stimulus. Patients with schizophrenia perform poorly in working memory tasks that require the brief memory of a target location in space. This deficit indicates that persistent neural activity related to spatial locations may be impaired in the disease. At the circuit level, many studies have shown that NMDA receptors and the dopamine system are involved in both schizophrenia pathology and working memory-related persistent activity. In this Hypothesis and Theory article, we examine the possible connection between NMDA receptors, the dopamine system, and schizophrenia-linked working memory deficits. In particular, we focus on the dopamine breakdown product homocysteine (HCY), which is consistently elevated in schizophrenia patients. Our previous studies have shown that HCY strongly reduces the desensitization of NMDA currents. Here, we show that HCY likely affects NMDA receptors in brain regions that support working memory; this is because these areas favor dopamine breakdown over transport to clear dopamine from synapses. Finally, within the context of two NMDA-based computational models of working memory, we suggest a mechanism by which HCY could give rise to the working memory deficits observed in schizophrenia patients.
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Affiliation(s)
- Andrew D Bolton
- Center for Brain Science, Harvard University, Cambridge, MA, United States
| | - Martha Constantine-Paton
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, United States
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9
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Dhami K, MacKay M, Maia-de-Oliveira JP, Hallak J, Todd K, Baker G, Dursun S. Novel Targets for Development of Drugs for Treating Schizophrenia: Focus on Glycine, D-Serine and Nitric Oxide. ACTA ACUST UNITED AC 2016. [DOI: 10.5455/bcp.20130629042437] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Kamaldeep Dhami
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Marnie MacKay
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Joao Paulo Maia-de-Oliveira
- National Institute of Science and Technology in Translational Medicine, Ribeirao Preto Medical School, Sao Paulo, Brazil
| | - Jaime Hallak
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- National Institute of Science and Technology in Translational Medicine, Ribeirao Preto Medical School, Sao Paulo, Brazil
| | - Kathryn Todd
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
| | - Glen Baker
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- National Institute of Science and Technology in Translational Medicine, Ribeirao Preto Medical School, Sao Paulo, Brazil
| | - Serdar Dursun
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada
- National Institute of Science and Technology in Translational Medicine, Ribeirao Preto Medical School, Sao Paulo, Brazil
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10
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Zheng HF, Wang WQ, Li XM, Rauw G, Baker GB. Body fluid levels of neuroactive amino acids in autism spectrum disorders: a review of the literature. Amino Acids 2016; 49:57-65. [PMID: 27686223 PMCID: PMC5241332 DOI: 10.1007/s00726-016-2332-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/08/2016] [Indexed: 01/08/2023]
Abstract
A review of studies on the body fluid levels of neuroactive amino acids, including glutamate, glutamine, taurine, gamma-aminobutyric acid (GABA), glycine, tryptophan, d-serine, and others, in autism spectrum disorders (ASD) is given. The results reported in the literature are generally inconclusive and contradictory, but there has been considerable variation among the previous studies in terms of factors such as age, gender, number of subjects, intelligence quotient, and psychoactive medication being taken. Future studies should include simultaneous analyses of a large number of amino acids [including d-serine and branched-chain amino acids (BCAAs)] and standardization of the factors mentioned above. It may also be appropriate to use saliva sampling to detect amino acids in ASD patients in the future—this is noninvasive testing that can be done easily more frequently than other sampling, thus providing more dynamic monitoring.
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Affiliation(s)
- Hui-Fei Zheng
- Mental Health Research Laboratory, Xiamen Xianyue Hospital, Xiamen, Fujian, China.,Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Wen-Qiang Wang
- Mental Health Research Laboratory, Xiamen Xianyue Hospital, Xiamen, Fujian, China.
| | - Xin-Min Li
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Gail Rauw
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Glen B Baker
- Neurochemical Research Unit, Department of Psychiatry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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11
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Bostrom C, Yau SY, Majaess N, Vetrici M, Gil-Mohapel J, Christie BR. Hippocampal dysfunction and cognitive impairment in Fragile-X Syndrome. Neurosci Biobehav Rev 2016; 68:563-574. [DOI: 10.1016/j.neubiorev.2016.06.033] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 01/03/2023]
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12
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Abstract
Excellent reviews on central N-methyl-D-aspartate receptor (NMDAR) signaling and function in cardiovascular regulating neuronal pools have been reported. However, much less attention has been given to NMDAR function in peripheral tissues, particularly the heart and vasculature, although a very recent review discusses such function in the kidney. In this short review, we discuss the NMDAR expression and complexity of its function in cardiovascular tissues. In conscious (contrary to anesthetized) rats, activation of the peripheral NMDAR triggers cardiovascular oxidative stress through the PI3K-ERK1/2-NO signaling pathway, which ultimately leads to elevation in blood pressure. Evidence also implicates Ca release, in the peripheral NMDAR-mediated pressor response. Despite evidence of circulating potent ligands (eg, D-aspartate and L-aspartate, L-homocysteic acid, and quinolinic acid) and also their coagonist (eg, glycine or D-serine), the physiological role of peripheral cardiovascular NMDAR remains elusive. Nonetheless, the cardiovascular relevance of the peripheral NMDAR might become apparent when its signaling is altered by drugs, such as alcohol, which interact with the NMDAR or its downstream signaling mechanisms.
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Affiliation(s)
- Marie A. McGee
- Oak Ridge Institute for Science and Education, Research Triangle Park, NC
| | - Abdel A. Abdel-Rahman
- Department of Pharmacology, Brody School of Medicine, East Carolina University, Greenville, NC 27834
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13
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Santini AC, Pierantoni GM, Gerlini R, Iorio R, Olabinjo Y, Giovane A, Di Domenico M, Sogos C. Glix 13, a new drug acting on glutamatergic pathways in children and animal models of autism spectrum disorders. BIOMED RESEARCH INTERNATIONAL 2014; 2014:234295. [PMID: 24605324 PMCID: PMC3925524 DOI: 10.1155/2014/234295] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 12/09/2013] [Indexed: 02/02/2023]
Abstract
Recently standardized diagnostic instruments have been developed in diagnostic and therapeutic procedures for Autism Spectrumv Disorders (ASD). According to the DSM-5 criteria, individuals with ASD must show symptoms from early childhood. These symptoms are communication deficits and restricted, repetitive patterns of behaviour. It was recently described by Bioinformatic analysis that 99 modified genes were associated with human autism. Gene expression patterns in the low-line animals show significant enrichment in autism-associated genes and the NMDA receptor gene family was identified among these. Using ultrasonic vocalizations, it was demonstrated that genetic variation has a direct impact on the expression of social interactions. It has been proposed that specific alleles interact with a social reward process in the adolescent mouse modifying their social interaction and their approach toward each other. In this review we report that the monoclonal antibody-derived tetrapeptide GLYX-13 was found to act as an N-methyl-D-aspartate receptor modulator and possesses the ability to readily cross the blood brain barrier. Treatment with the NMDAR glycine site partial agonist GLYX-13 rescued the deficit in the animal model. Thus, the NMDA receptor has been shown to play a functional role in autism, and GLYX-13 shows promise for the treatment of autism in autistic children.
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Affiliation(s)
- Annamaria Chiara Santini
- Dipartimento di Pediatria e Neuropsichiatria Infantile, Università di Roma La Sapienza, Via dei Sabelli 108, 00185 Roma, Italy
| | - Giovanna Maria Pierantoni
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via Pansini 5, 80131 Napoli, Italy
| | - Raffaele Gerlini
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Via Pansini 5, 80131 Napoli, Italy
| | - Rosamaria Iorio
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università degli Studi di Napoli, Via De Crecchio 7, 80138 Napoli, Italy
| | - Yinka Olabinjo
- Dipartimento di Medicina, Chirurgia e Neuroscienze, Università di Siena, Policlinico Santa Maria alle Scotte, Viale Mario Bracci 16, 53100 Siena, Italy
| | - Alfonso Giovane
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università degli Studi di Napoli, Via De Crecchio 7, 80138 Napoli, Italy
| | - Marina Di Domenico
- Dipartimento di Biochimica, Biofisica e Patologia Generale, Seconda Università degli Studi di Napoli, Via De Crecchio 7, 80138 Napoli, Italy
| | - Carla Sogos
- Dipartimento di Pediatria e Neuropsichiatria Infantile, Università di Roma La Sapienza, Via dei Sabelli 108, 00185 Roma, Italy
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14
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Muller-Chrétien E. Outside-out "sniffer-patch" clamp technique for in situ measures of neurotransmitter release. Methods Mol Biol 2014; 1183:195-204. [PMID: 25023310 DOI: 10.1007/978-1-4939-1096-0_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The mechanism underlying neurotransmitter release is a critical research domain for the understanding of neuronal network function; however, few techniques are available for the direct detection and measurement of neurotransmitter release. To date, the sniffer-patch clamp technique is mainly used to investigate these mechanisms from individual cultured cells. In this study, we propose to adapt the sniffer-patch clamp technique to in situ detection of neurosecretion. Using outside-out patches from donor cells as specific biosensors plunged in acute cerebral slices, this technique allows for proper detection and quantification of neurotransmitter release at the level of the neuronal network.
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Affiliation(s)
- Emilie Muller-Chrétien
- Centre d'Investigation Clinique, Hospices Civils de Lyon, Hôpital des Charpennes, 27 rue Gabriel Péri, Villeurbanne, 69100, France,
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15
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Dhami K, Churchward M, Baker G, Todd K. Fluoxetine and citalopram decrease microglial release of glutamate and d-serine to promote cortical neuronal viability following ischemic insult. Mol Cell Neurosci 2013; 56:365-74. [DOI: 10.1016/j.mcn.2013.07.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 06/20/2013] [Accepted: 07/14/2013] [Indexed: 12/12/2022] Open
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16
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Bolton AD, Phillips MA, Constantine-Paton M. Homocysteine reduces NMDAR desensitization and differentially modulates peak amplitude of NMDAR currents, depending on GluN2 subunit composition. J Neurophysiol 2013; 110:1567-82. [PMID: 23864370 DOI: 10.1152/jn.00809.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
N-methyl-d-aspartate receptors (NMDARs) have been linked to schizophrenia because agents that bind the receptor, like ketamine and phencyclidine, are capable of inducing schizophrenia-like symptoms. Here we show that the amino acid homocysteine (HCY), which is increased in the blood of schizophrenia patients, reduces desensitization of NMDARs in cultured mouse neurons, human embryonic kidney cells transfected with GluN1 + GluN2A, GluN2B, or GluN2D subunits, and hippocampal slices. HCY also alters the peak amplitude of NMDAR currents, depending on the GluN2 subunit the receptor contains; GluN1 + GluN2A-containing NMDARs show an increase in peak amplitude when exposed to HCY, while GluN1 + GluN2B-containing NMDARs show a decrease in peak amplitude. Both peak amplitude and desensitization effects of HCY can be occluded by saturating the NMDAR with glycine. Since glycine concentrations are not saturating in the brain, HCY could play an NMDAR-modulating role in the nervous system. We also show that HCY shares characteristics with glutamate and suggest that HCY affects both the agonist and co-agonist site of the NMDAR.
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Affiliation(s)
- Andrew D Bolton
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts
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17
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Muller E, Bakkar W, Martina M, Sokolovski A, Wong A, Legendre P, Bergeron R. Vesicular storage of glycine in glutamatergic terminals in mouse hippocampus. Neuroscience 2013; 242:110-27. [DOI: 10.1016/j.neuroscience.2013.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/06/2013] [Accepted: 03/10/2013] [Indexed: 11/15/2022]
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18
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Otte DM, Barcena de Arellano ML, Bilkei-Gorzo A, Albayram Ö, Imbeault S, Jeung H, Alferink J, Zimmer A. Effects of Chronic D-Serine Elevation on Animal Models of Depression and Anxiety-Related Behavior. PLoS One 2013; 8:e67131. [PMID: 23805296 PMCID: PMC3689701 DOI: 10.1371/journal.pone.0067131] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 05/15/2013] [Indexed: 12/17/2022] Open
Abstract
NMDA receptors are activated after binding of the agonist glutamate to the NR2 subunit along with a co-agonist, either L-glycine or D-serine, to the NR1 subunit. There is substantial evidence to suggest that D-serine is the most relevant co-agonist in forebrain regions and that alterations in D-serine levels contribute to psychiatric disorders. D-serine is produced through isomerization of L-serine by serine racemase (Srr), either in neurons or in astrocytes. It is released by astrocytes by an activity-dependent mechanism involving secretory vesicles. In the present study we generated transgenic mice (SrrTg) expressing serine racemase under a human GFAP promoter. These mice were biochemically and behaviorally analyzed using paradigms of anxiety, depression and cognition. Furthermore, we investigated the behavioral effects of long-term administration of D-serine added to the drinking water. Elevated brain D-serine levels in SrrTg mice resulted in specific behavioral phenotypes in the forced swim, novelty suppression of feeding and olfactory bulbectomy paradigms that are indicative of a reduced proneness towards depression-related behavior. Chronic dietary D-serine supplement mimics the depression-related behavioral phenotype observed in SrrTg mice. Our results suggest that D-serine supplementation may improve mood disorders.
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Affiliation(s)
- David-Marian Otte
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
| | | | | | - Önder Albayram
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
| | - Sophie Imbeault
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
| | - Haang Jeung
- Department of Psychiatry, University of Bonn, Bonn, Germany
| | - Judith Alferink
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
- Department of Psychiatry, University of Bonn, Bonn, Germany
| | - Andreas Zimmer
- Institute of Molecular Psychiatry, University of Bonn, Bonn, Germany
- * E-mail:
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19
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Paula-Lima AC, Brito-Moreira J, Ferreira ST. Deregulation of excitatory neurotransmission underlying synapse failure in Alzheimer's disease. J Neurochem 2013; 126:191-202. [PMID: 23668663 DOI: 10.1111/jnc.12304] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 05/09/2013] [Accepted: 05/10/2013] [Indexed: 12/12/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia in the elderly. Memory loss in AD is increasingly attributed to soluble oligomers of the amyloid-β peptide (AβOs), toxins that accumulate in AD brains and target particular synapses. Glutamate receptors appear to be centrally involved in synaptic targeting by AβOs. Once bound to neurons, AβOs dysregulate the activity and reduce the surface expression of both N-methyl-D-aspartate (NMDA) and 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid (AMPA) types of glutamate receptors, impairing signaling pathways involved in synaptic plasticity. In the extracellular milieu, AβOs promote accumulation of the excitatory amino acids, glutamate and D-serine. This leads to overactivation of glutamate receptors, triggering abnormal calcium signals with noxious impacts on neurons. Here, we review key findings linking AβOs to deregulated glutamate neurotransmission and implicating this as a primary mechanism of synapse failure in AD. We also discuss strategies to counteract the impact of AβOs on excitatory neurotransmission. In particular, we review evidence showing that inducing neuronal hyperpolarization via activation of inhibitory GABA(A) receptors prevents AβO-induced excitotoxicity, suggesting that this could comprise a possible therapeutic approach in AD.
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Affiliation(s)
- Andrea C Paula-Lima
- Department of Basic Sciences, Faculty of Dentistry, University of Chile, Santiago, Chile.
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20
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Martina M, Comas T, Mealing GAR. Selective Pharmacological Modulation of Pyramidal Neurons and Interneurons in the CA1 Region of the Rat Hippocampus. Front Pharmacol 2013; 4:24. [PMID: 23493925 PMCID: PMC3595640 DOI: 10.3389/fphar.2013.00024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/19/2013] [Indexed: 11/25/2022] Open
Abstract
The hippocampus is a complex network tightly regulated by interactions between excitatory and inhibitory neurons. In neurodegenerative disorders where cognitive functions such as learning and memory are impaired this excitation-inhibition balance may be altered. Interestingly, the uncompetitive N-methyl-d-aspartate receptor (NMDAR) antagonist memantine, currently in clinical use for the treatment of Alzheimer’s disease, may alter the excitation-inhibition balance in the hippocampus. However, the specific mechanism by which memantine exerts this action is not clear. To better elucidate the effect of memantine on hippocampal circuitry, we studied its pharmacology on NMDAR currents in both pyramidal cells (PCs) and interneurons (Ints) in the CA1 region of the hippocampus. Applying whole-cell patch-clamp methodology to acute rat hippocampal slices, we report that memantine antagonism is more robust in PCs than in Ints. Using specific NMDAR subunit antagonists, we determined that this selective antagonism of memantine is attributable to specific differences in the molecular make-up of the NMDARs in excitatory and inhibitory neurons. These findings offer new insight into the mechanism of action and therapeutic potential of NMDA receptor pharmacology in modulating hippocampal excitability.
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Affiliation(s)
- Marzia Martina
- Human Health Therapeutics, National Research Council of Canada Ottawa, ON, Canada
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21
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Abstract
Metaplasticity, the adaptive changes of long-term potentiation (LTP) and long-term depression (LTD) in response to fluctuations in neural activity is well documented in visual cortex, where dark rearing shifts the frequency threshold for the induction of LTP and LTD. Here we studied metaplasticity affecting spike-timing-dependent plasticity, in which the polarity of plasticity is determined not by the stimulation frequency, but by the temporal relationship between near-coincidental presynaptic and postsynaptic firing. We found that in mouse visual cortex the same regime of deprivation that restricts the frequency range for inducing rate-dependent LTD extends the integration window for inducing timing-dependent LTD, enabling LTD induction with random presynaptic and postsynaptic firing. Notably, the underlying mechanism for the changes in both rate-dependent and time-dependent LTD appears to be an increase of NR2b-containing NMDAR at the synapse. Thus, the rules of metaplasticity might manifest in opposite directions, depending on the plasticity-induction paradigms.
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22
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Lee HU, Yamazaki Y, Tanaka KF, Furuya K, Sokabe M, Hida H, Takao K, Miyakawa T, Fujii S, Ikenaka K. Increased astrocytic ATP release results in enhanced excitability of the hippocampus. Glia 2012; 61:210-24. [PMID: 23018918 DOI: 10.1002/glia.22427] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 09/04/2012] [Indexed: 11/05/2022]
Abstract
Astrocytes, a major subtype of glia, interact with neurons as a supportive partner supplying energy sources and growth factors. Astrocytes regulate the activity of neighboring neurons by releasing chemical transmitters (gliotransmitters). However, the precise role of gilotransmitters in regulating neuronal activity is still under debate. Here, we report that a subtle enhancement in the release of one gliotransmitter, ATP, affects synaptic potentiation from an analysis of mice containing an astrocyte-selective (GFAP) mutation. We found that, relative to normal mice, weaker stimulation induced long-term potentiation (LTP) in mutant mice, indicating that the threshold to induce LTP was lowered in the mutant. While excitatory transmission was normal in the mutant, inhibitory GABAergic transmission was suppressed. We found that a low concentration of adenosine selectively attenuated inhibitory neuronal activity and lowered the threshold to induce LTP in wild type mice. In comparison, adenosine A(1) receptor antagonism reversed the lowered LTP threshold back to normal in the mutant mouse. We verified that adenosine levels in the cerebrospinal fluid of mutant mice were slightly elevated compared to wild type mice. This was apparently caused by an increase in ATP release from mutant astrocytes that could provide a source of augmented adenosine levels in the mutant. ATP is thought to suppress the excitability of neuronal circuits; however, a small increase in ATP release can result in a suppressed inhibitory tone and enhanced excitability of neuronal circuitry. These findings demonstrate that ATP released from astrocytes acts in a bidirectional fashion to regulate neuronal excitability depending on concentration.
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Affiliation(s)
- Hae Ung Lee
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki 444-8787, Japan
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23
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Billard JM. d-Amino acids in brain neurotransmission and synaptic plasticity. Amino Acids 2012; 43:1851-60. [DOI: 10.1007/s00726-012-1346-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/16/2012] [Indexed: 01/25/2023]
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24
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Xiao X, Yang Y, Zhang Y, Zhang XM, Zhao ZQ, Zhang YQ. Estrogen in the Anterior Cingulate Cortex Contributes to Pain-Related Aversion. Cereb Cortex 2012; 23:2190-203. [DOI: 10.1093/cercor/bhs201] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Sullivan SJ, Miller RF. AMPA receptor-dependent, light-evoked D-serine release acts on retinal ganglion cell NMDA receptors. J Neurophysiol 2012; 108:1044-51. [PMID: 22592312 DOI: 10.1152/jn.00264.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
NMDA receptor (NMDAR) activation requires coincident binding of the excitatory neurotransmitter glutamate and a coagonist, either glycine or D-serine. Changes in NMDAR currents during neural transmission are typically attributed to glutamate release against a steady background of coagonist, excluding the possibility of coagonist release. AMPA receptor (AMPAR) stimulation evokes D-serine release, but it is unknown whether this is a physiological phenomenon capable of influencing synaptic responses. In this study, we utilized the intact retina to determine whether light-evoked synaptic activity in retinal ganglion cells (RGCs) is shaped by a dynamic pool of coagonist. The application of AMPAR antagonist abolished light-evoked NMDAR currents, which were rescued by adding coagonist to the bath. When NMDA was globally applied to RGCs via bath or picospritzing, the coagonist occupancy was also dependent on AMPARs but to a lesser extent than that observed during light responses, suggesting a difference in extrasynaptic coagonist regulation. By saturating the glutamate binding site of NMDARs, we were able to detect released coagonist reaching RGCs during light-evoked responses. Mutant mice lacking the d-serine-synthesizing enzyme serine racemase were deficient in coagonist release. Coagonist release in wild-type retinas was notably greater in ON than in OFF responses and depended on AMPARs. These findings suggest activity-dependent modulation of coagonist availability, particularly D-serine, and may add an extra dimension to NMDAR coincidence detection in the retina.
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Affiliation(s)
- Steve J Sullivan
- Univ. of Minnesota, Dept. of Neuroscience, Minneapolis, MN 55455, USA.
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26
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Akgul G, Wollmuth LP. Expression pattern of membrane-associated guanylate kinases in interneurons of the visual cortex. J Comp Neurol 2011; 518:4842-54. [PMID: 21031555 DOI: 10.1002/cne.22491] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
GABAergic interneurons are key elements regulating the activity of local circuits, and abnormal inhibitory circuits are implicated in certain psychiatric and neurodevelopmental diseases. The glutamatergic input that interneurons receive is a key determinant of their activity, yet its molecular structure and development, which are often distinct from those of glutamatergic input to pyramidal cells, are poorly defined. The membrane-associated guanylate kinase (MAGUK) homologs PSD-95/SAP90, PSD-93/chapsyn110, SAP97, and SAP102 are central organizers of the postsynaptic density at excitatory synapses on pyramidal neurons. We therefore studied the cell-type-specific and developmental expression of MAGUKs in the nonoverlapping parvalbumin (PV)- and somatostatin (SOM)-positive interneurons in the visual cortex. These interneuron subtypes account for the vast majority of interneurons in the cortex and have different functional properties and postsynaptic structures, being either axodendritic (PV(+)) or axospinous (SOM(+)). To study cell-type-specific MAGUK expression, we used DIG-labeled riboprobes against each MAGUK along with antibodies against either PV or SOM and examined tissue from juvenile (P15) and adult mice. Both PV(+) and SOM(+) interneurons express mRNA for PSD-95, PSD-93, and SAP102 in P15 and adult tissue. In contrast, these interneuron subtypes express SAP97 at P15, but for adult visual cortex we found that most PV(+) and SOM(+) interneurons show low or no expression of SAP97. Given the importance of SAP97 in regulating AMPA receptor GluA1 subunit and NMDA receptor subunits at glutamatergic synapses, these results suggest a developmental shift in glutamate receptor subunit composition and regulation of glutamatergic synapses on PV(+) and SOM(+) interneurons.
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Affiliation(s)
- Gulcan Akgul
- State University of New York at Stony Brook, 11794-5230, USA
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27
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Lin CH, Lane HY, Tsai GE. Glutamate signaling in the pathophysiology and therapy of schizophrenia. Pharmacol Biochem Behav 2011; 100:665-77. [PMID: 21463651 DOI: 10.1016/j.pbb.2011.03.023] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 03/14/2011] [Accepted: 03/28/2011] [Indexed: 11/26/2022]
Abstract
Glutamatergic neurotransmission, particularly through the N-methyl-d-aspartate (NMDA) receptor, has drawn attention for its role in the pathophysiology of schizophrenia. This paper reviews the neurodevelopmental origin and genetic susceptibility of schizophrenia relevant to NMDA neurotransmission, and discusses the relationship between NMDA hypofunction and different domains of symptom in schizophrenia as well as putative treatment modality for the disorder. A series of clinical trials and a meta-analysis which compared currently available NMDA-enhancing agents suggests that glycine, d-serine, and sarcosine are more efficacious than d-cycloserine in improving the overall psychopathology of schizophrenia without side effect or safety concern. In addition, enhancing glutamatergic neurotransmission via activating the AMPA receptor, metabotropic glutamate receptor or inhibition of d-amino acid oxidase (DAO) is also reviewed. More studies are needed to determine the NMDA vulnerability in schizophrenia and to confirm the long-term efficacy, functional outcome, and safety of these NMDA-enhancing agents in schizophrenic patients, particularly those with refractory negative and cognitive symptoms, or serious adverse effects while taking the existing antipsychotic agents.
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Affiliation(s)
- Chieh-Hsin Lin
- Department of Psychiatry, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan
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28
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Labrie V, Wong AHC, Roder JC. Contributions of the D-serine pathway to schizophrenia. Neuropharmacology 2011; 62:1484-503. [PMID: 21295046 DOI: 10.1016/j.neuropharm.2011.01.030] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 01/16/2011] [Accepted: 01/19/2011] [Indexed: 01/30/2023]
Abstract
The glutamate neurotransmitter system is one of the major candidate pathways for the pathophysiology of schizophrenia, and increased understanding of the pharmacology, molecular biology and biochemistry of this system may lead to novel treatments. Glutamatergic hypofunction, particularly at the NMDA receptor, has been hypothesized to underlie many of the symptoms of schizophrenia, including psychosis, negative symptoms and cognitive impairment. This review will focus on D-serine, a co-agonist at the NMDA receptor that in combination with glutamate, is required for full activation of this ion channel receptor. Evidence implicating D-serine, NMDA receptors and related molecules, such as D-amino acid oxidase (DAO), G72 and serine racemase (SRR), in the etiology or pathophysiology of schizophrenia is discussed, including knowledge gained from mouse models with altered D-serine pathway genes and from preliminary clinical trials with D-serine itself or compounds modulating the D-serine pathway. Abnormalities in D-serine availability may underlie glutamatergic dysfunction in schizophrenia, and the development of new treatments acting through the D-serine pathway may significantly improve outcomes for many schizophrenia patients.
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Affiliation(s)
- Viviane Labrie
- Krembil Family Epigenetics Laboratory, Centre for Addiction and Mental Health, 250 College St, Toronto, ON M5T 1R8, Canada.
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29
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Potier B, Turpin FR, Sinet PM, Rouaud E, Mothet JP, Videau C, Epelbaum J, Dutar P, Billard JM. Contribution of the d-Serine-Dependent Pathway to the Cellular Mechanisms Underlying Cognitive Aging. Front Aging Neurosci 2010; 2:1. [PMID: 20552041 PMCID: PMC2874399 DOI: 10.3389/neuro.24.001.2010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 01/07/2010] [Indexed: 01/04/2023] Open
Abstract
An association between age-related memory impairments and changes in functional plasticity in the aging brain has been under intense study within the last decade. In this article, we show that an impaired activation of the strychnine-insensitive glycine site of N-methyl-d-aspartate receptors (NMDA-R) by its agonist d-serine contributes to deficits of synaptic plasticity in the hippocampus of memory-impaired aged rats. Supplementation with exogenous d-serine prevents the age-related deficits of isolated NMDA-R-dependent synaptic potentials as well as those of theta-burst-induced long-term potentiation and synaptic depotentiation. Endogenous levels of d-serine are reduced in the hippocampus with aging, that correlates with a weaker expression of serine racemase synthesizing the amino acid. On the contrary, the affinity of d-serine binding to NMDA-R is not affected by aging. These results point to a critical role for the d-serine-dependent pathway in the functional alterations of the brain underlying memory impairment and provide key information in the search for new therapeutic strategies for the treatment of memory deficits in the elderly.
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Affiliation(s)
- B Potier
- Centre de Psychiatrie et Neurosciences, INSERM, U894, Faculté de Médecine, Université Paris Descartes Paris, France
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30
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Abstract
D-amino acid oxidase (DAO) is a flavoenzyme that metabolizes certain D-amino acids, notably the endogenous N-methyl D-aspartate receptor (NMDAR) co-agonist, D-serine. As such, it has the potential to modulate the function of NMDAR and to contribute to the widely hypothesized involvement of NMDAR signalling in schizophrenia. Three lines of evidence now provide support for this possibility: DAO shows genetic associations with the disorder in several, although not all, studies; the expression and activity of DAO are increased in schizophrenia; and DAO inactivation in rodents produces behavioural and biochemical effects, suggestive of potential therapeutic benefits. However, several key issues remain unclear. These include the regional, cellular and subcellular localization of DAO, the physiological importance of DAO and its substrates other than D-serine, as well as the causes and consequences of elevated DAO in schizophrenia. Herein, we critically review the neurobiology of DAO, its involvement in schizophrenia, and the therapeutic value of DAO inhibition. This review also highlights issues that have a broader relevance beyond DAO itself: how should we weigh up convergent and cumulatively impressive, but individually inconclusive, pieces of evidence regarding the role that a given gene may have in the aetiology, pathophysiology and pharmacotherapy of schizophrenia?
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Vardigan JD, Huszar SL, McNaughton CH, Hutson PH, Uslaner JM. MK-801 produces a deficit in sucrose preference that is reversed by clozapine, D-serine, and the metabotropic glutamate 5 receptor positive allosteric modulator CDPPB: relevance to negative symptoms associated with schizophrenia? Pharmacol Biochem Behav 2010; 95:223-9. [PMID: 20122952 DOI: 10.1016/j.pbb.2010.01.010] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/15/2010] [Accepted: 01/26/2010] [Indexed: 11/29/2022]
Abstract
Currently prescribed antipsychotics attenuate the positive symptoms of schizophrenia but fail or only mildly improve negative symptoms. The present study aimed to establish an animal model of negative symptoms by examining the effects of the NMDA receptor antagonist MK-801 on sucrose preference. We sought to validate the model by examining the effects of clozapine and D-serine, for which there are positive clinical data regarding their effects on negative symptoms, and haloperidol which is clinically ineffective. We extended our analysis by examining CDPPB, an mGlu5 receptor positive allosteric modulator. Acute MK-801 produced effects indicative of a shift in the hedonic experience of sucrose not confounded by disruptions in motor abilities or taste as revealed by: 1) a decrease in sucrose intake at low concentrations (0.8% or 1.2%), but no effect on water, 2) an increase in consumption for higher (7%) sucrose concentrations, reflecting a shift to the right in the concentration-consumption curve, and 3) no effect on quinine intake. Sub-chronic clozapine and acute d-serine attenuated the MK-801-induced deficit in 1.2% sucrose consumption, whereas sub-chronic haloperidol (0.02 mg/kg) did not. Finally, acute treatment with CDPPB also attenuated this deficit. These data suggest that this model may be useful for identifying novel agents that improve negative symptoms, and that compounds which enhance NMDA receptor function, such as mGlu5 receptor PAMs, may have clinical utility in this regard.
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Daniels BA, Baldridge WH. d-Serine enhancement of NMDA receptor-mediated calcium increases in rat retinal ganglion cells. J Neurochem 2009; 112:1180-9. [PMID: 19968757 DOI: 10.1111/j.1471-4159.2009.06532.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
NMDA receptor (NMDAR) activation is enhanced by d-serine or glycine acting at a specific binding site. Previous work has shown d-serine enhancement of NMDAR currents in retinal ganglion cells. One of the major functions of most NMDA channels is to permit calcium influx into cells. We show that d-serine enhances glutamate-induced calcium responses in immunopanned retinal ganglion cells. This effect was specific to NMDA receptors as similar results were found with NMDA, but not kainate, and was reduced or blocked by modulators of the NMDAR coagonist binding site. d-Serine and glycine enhanced glutamate-induced calcium responses in a dose-dependent manner and at equimolar concentrations there was no difference in the efficacy of the coagonists. In isolated retinas NMDA-induced calcium responses were enhanced by d-serine coapplication in 46% of ganglion cells. Endogenous d-serine degradation by treatment with d-amino acid oxidase caused a approximately 45% decrease in the NMDA-induced response that could be reversed by coapplication with d-serine. d-Serine and glycine were equally effective in enhancing glutamatergic calcium responses. Endogenous d-serine contributes to NMDAR activation in retinal wholemounts and some but not all retinal ganglion cells may experience saturating levels of d-serine or glycine.
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Affiliation(s)
- Bryan A Daniels
- Laboratory for Retina and Optic Nerve Research, Neuroscience Institute, Departments of Anatomy & Neurobiology and Ophthalmology & Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
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NMDA NR2A and NR2B receptors in the rostral anterior cingulate cortex contribute to pain-related aversion in male rats. Pain 2009; 146:183-93. [PMID: 19695778 DOI: 10.1016/j.pain.2009.07.027] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/07/2009] [Accepted: 07/22/2009] [Indexed: 11/23/2022]
Abstract
NMDA receptors, which are implicated in pain processing, are highly expressed in forebrain areas including the anterior cingulate cortex (ACC). The ACC has been implicated in the affective response to noxious stimuli. Using a combination of immunohistochemical staining, Western blot, electrophysiological recording and formalin-induced conditioned place avoidance (F-CPA) rat behavioral model that directly reflects the affective component of pain, the present study examined formalin nociceptive conditioning-induced changes in the expressions of NMDA receptor subunits NR1, NR2A, and NR2B in the rostral ACC (rACC) and its possible functional significance. We found that unilateral intraplantar (i.pl.) injection of dilute formalin with or without contextual conditioning exposure markedly increased the expressions of NMDA receptor subunits NR2A and NR2B but not of NR1 in the bilateral rACC. NMDA-evoked currents in rACC neurons were significantly greater in formalin-injected rats than in naïve or normal saline-injected rats. Selectively blocking either NR2A or NR2B subunit in the rACC abolished the acquisition of F-CPA and formalin nociceptive conditioning-induced Fos expression, but it did not affect formalin acute nociceptive behaviors and non-nociceptive fear stimulus-induced CPA. These results suggest that both NMDA receptor subunits NR2A and NR2B in the rACC are critically involved in pain-related aversion. Thus, a new strategy targeted at NMDA NR2A or NR2B subunit might be raised for the prevention of pain-related emotional disturbance.
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Labrie V, Roder JC. The involvement of the NMDA receptor D-serine/glycine site in the pathophysiology and treatment of schizophrenia. Neurosci Biobehav Rev 2009; 34:351-72. [PMID: 19695284 DOI: 10.1016/j.neubiorev.2009.08.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 08/10/2009] [Accepted: 08/11/2009] [Indexed: 01/11/2023]
Abstract
Hypofunction of the N-methyl-D-aspartate receptor (NMDAR) has been implicated in the pathophysiology of schizophrenia. The NMDAR contains a D-serine/glycine site on the NR1 subunit that may be a promising therapeutic target for psychiatric illness. This review outlines the complex regulation of endogenous NMDAR D-serine/glycine site agonists and explores their contribution to schizophrenia pathogenesis and their potential clinical utility. Genetic studies have associated genes influencing NMDAR D-serine/glycine site activation with an increased susceptibility to schizophrenia. Postmortem studies have identified abnormalities in several transcripts affecting D-serine/glycine site activity, consistent with in vivo reports of alterations in levels of endogenous D-serine/glycine site agonists and antagonists. Genetically modified mice with aberrant NMDAR D-serine/glycine site function model certain features of the negative and cognitive symptoms of schizophrenia, and similar behavioral abnormalities have been observed in other candidate genes models. Compounds that directly activate the NMDAR D-serine/glycine site or inhibit glycine transport have demonstrated beneficial effects in preclinical models and clinical trials. Future pharmacological approaches for schizophrenia treatment may involve targeting enzymes that affect D-serine synthesis and metabolism.
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Affiliation(s)
- Viviane Labrie
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada.
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Ascoli GA, Brown KM, Calixto E, Card JP, Galván EJ, Perez-Rosello T, Barrionuevo G. Quantitative morphometry of electrophysiologically identified CA3b interneurons reveals robust local geometry and distinct cell classes. J Comp Neurol 2009; 515:677-95. [PMID: 19496174 DOI: 10.1002/cne.22082] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The morphological and electrophysiological diversity of inhibitory cells in hippocampal area CA3 may underlie specific computational roles and is not yet fully elucidated. In particular, interneurons with somata in strata radiatum (R) and lacunosum-moleculare (L-M) receive converging stimulation from the dentate gyrus and entorhinal cortex as well as within CA3. Although these cells express different forms of synaptic plasticity, their axonal trees and connectivity are still largely unknown. We investigated the branching and spatial patterns, plus the membrane and synaptic properties, of rat CA3b R and L-M interneurons digitally reconstructed after intracellular labeling. We found considerable variability within but no difference between the two layers, and no correlation between morphological and biophysical properties. Nevertheless, two cell types were identified based on the number of dendritic bifurcations, with significantly different anatomical and electrophysiological features. Axons generally branched an order of magnitude more than dendrites. However, interneurons on both sides of the R/L-M boundary revealed surprisingly modular axodendritic arborizations with consistently uniform local branch geometry. Both axons and dendrites followed a lamellar organization, and axons displayed a spatial preference toward the fissure. Moreover, only a small fraction of the axonal arbor extended to the outer portion of the invaded volume, and tended to return toward the proximal region. In contrast, dendritic trees demonstrated more limited but isotropic volume occupancy. These results suggest a role of predominantly local feedforward and lateral inhibitory control for both R and L-M interneurons. Such a role may be essential to balance the extensive recurrent excitation of area CA3 underlying hippocampal autoassociative memory function.
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Affiliation(s)
- Giorgio A Ascoli
- Center for Neural Informatics, Structures, & Plasticity, and Molecular Neuroscience Department, Krasnow Institute for Advanced Study, George Mason University, 4400 University Drive, Fairfax, VA 22030-4444, USA.
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Abstract
A subset of glutamate receptors that are specifically sensitive to the glutamate analog N-methyl-D-aspartate (NMDA) are molecular coincidence detectors, necessary for activity-dependent processes of neurodevelopment and in sensory and cognitive functions. The activity of these receptors is modulated by the endogenous amino acid D-serine, but the extent to which D-serine is necessary for the normal development and function of the mammalian nervous system was previously unknown. Decreased signaling at NMDA receptors has been implicated in the pathophysiology of schizophrenia based on pharmacological evidence, and several human genes related to D-serine metabolism and glutamatergic neurotransmission have been implicated in the etiology of schizophrenia. Here we show that genetically modified mice lacking the ability to produce D-serine endogenously have profoundly altered glutamatergic neurotransmission, and relatively subtle but significant behavioral abnormalities that reflect hyperactivity and impaired spatial memory, and that are consistent with elevated anxiety.
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Coagonist release modulates NMDA receptor subtype contributions at synaptic inputs to retinal ganglion cells. J Neurosci 2009; 29:1469-79. [PMID: 19193893 DOI: 10.1523/jneurosci.4240-08.2009] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
NMDA receptors (NMDARs) are tetrameric protein complexes usually comprising two NR1 and two NR2 subunits. Different combinations of four potential NR2 subunits (NR2A-D) confer diversity in developmental expression, subsynaptic localization, and functional characteristics, including affinity for neurotransmitter. NR2B-containing NMDARs, for example, exhibit relatively high affinity both for glutamate and the coagonist glycine. Although multiple NMDAR subtypes can colocalize at individual synapses, particular subtypes often mediate inputs from distinct functional pathways. In retinal ganglion cells (RGCs), NMDARs contribute to synaptic responses elicited by light stimulus onset ("ON") and offset ("OFF"), but roles for particular NMDAR subtypes, and potential segregation between the ON and OFF pathways, have not been explored. Moreover, elements in the retinal circuitry release two different NMDAR coagonists, glycine and d-serine, but the effects of endogenous coagonist release on the relative contribution of different NMDAR subtypes are unclear. Here, we show that coagonist release within the retina modulates the relative contribution of different NMDARs in the ON pathway of the rat retina. By pharmacologically stimulating functional pathways independently in acute slices and recording synaptic responses in RGCs, we show that ON inputs, but not OFF inputs, are mediated in part by NMDARs exhibiting NR2B-like pharmacology. Furthermore, suppressing release of NMDAR coagonist reduces NMDAR activation at ON synapses and increases the relative contribution of these putative NR2B-containing receptors. These results demonstrate direct evidence for evoked coagonist release onto NMDARs and indicate that modulating coagonist release may regulate the relative activation of different NMDAR subtypes in the ON pathway.
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Yang CR, Svensson KA. Allosteric modulation of NMDA receptor via elevation of brain glycine and d-serine: The therapeutic potentials for schizophrenia. Pharmacol Ther 2008; 120:317-32. [DOI: 10.1016/j.pharmthera.2008.08.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Accepted: 08/12/2008] [Indexed: 12/20/2022]
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Gozzi A, Herdon H, Schwarz A, Bertani S, Crestan V, Turrini G, Bifone A. Pharmacological stimulation of NMDA receptors via co-agonist site suppresses fMRI response to phencyclidine in the rat. Psychopharmacology (Berl) 2008; 201:273-84. [PMID: 18704372 DOI: 10.1007/s00213-008-1271-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Accepted: 07/21/2008] [Indexed: 11/24/2022]
Abstract
RATIONALE Increasing experimental evidence suggests that impaired N-methyl-D: -aspartic acid (NMDA) receptor (NMDAr) function could be a key pathophysiological determinant of schizophrenia. Agonists at the allosteric glycine (Gly) binding site of the NMDA complex can promote NMDAr activity, a strategy that could provide therapeutic efficacy for the disorder. NMDAr antagonists like phencyclidine (PCP) can induce psychotic and dissociative symptoms similar to those observed in schizophrenia and are therefore widely used experimentally to impair NMDA neurotransmission in vivo. OBJECTIVES In the present study, we used pharmacological magnetic resonance imaging (phMRI) to investigate the modulatory effects of endogenous and exogenous agonists at the NMDAr Gly site on the spatiotemporal patterns of brain activation induced by acute PCP challenge in the rat. The drugs investigated were D: -serine, an endogenous agonist of the NMDAr Gly site, and SSR504734, a potent Gly transporter type 1 (GlyT-1) inhibitor that can potentiate NMDAr function by increasing synaptic levels of Gly. RESULTS Acute administration of PCP induced robust and sustained activation of discrete cortico-limbo-thalamic circuits. Pretreatment with D: -serine (1 g/kg) or SSR504734 (10 mg/kg) completely inhibited PCP-induced functional activation. This effect was accompanied by weak but sustained deactivation particularly in cortical areas. CONCLUSIONS These findings suggest that agents that stimulate NMDAr via Gly co-agonist site can potentiate NMDAr activity in the living brain and corroborate the potential for this class of drugs to provide selective enhancement of NMDAr neurotransmission in schizophrenia.
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Affiliation(s)
- Alessandro Gozzi
- Biology, Neurosciences CEDD, GlaxoSmithKline Medicines Research Centre, Verona, Italy.
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40
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Martina M, Bergeron R. D1 and D4 dopaminergic receptor interplay mediates coincident G protein-independent and dependent regulation of glutamate NMDA receptors in the lateral amygdala. J Neurochem 2008; 106:2421-35. [PMID: 18662324 DOI: 10.1111/j.1471-4159.2008.05584.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Dopamine (DA) receptor and NMDA receptor (NMDAR) activation in the lateral (LA) nucleus of the amygdala plays a critical role in emotional processing. Several distinct mechanisms regulate the molecular cross-talk between DA receptors and NMDARs in different brain regions; however, the cellular mechanism through which DA modulates NMDARs in LA projection neurons has not been studied. Here, we investigated the effect of DA receptor activation on NMDAR currents in LA projection neurons recorded in amygdala slices obtained from young rats. We found that DA reduces NMDAR current amplitudes in an additive manner through the activation of both D1-like and D2-like receptors. The reduction of NMDAR current amplitudes by D1-like receptor activation is mediated by a protein-protein interaction between the D1R and the NMDAR, while the regulation of NMDAR activity by D2-like receptors is elicited through a G protein-dependent pathway controlled by D4R. The results of our investigation show for the first time a functional interplay between D1R and D4R that mediates coincident G protein-independent and dependent regulation of NMDARs.
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Affiliation(s)
- Marzia Martina
- Department of Psychiatry, University of Ottawa, Ottawa, Ontario, Canada.
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41
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Billard JM. D-serine signalling as a prominent determinant of neuronal-glial dialogue in the healthy and diseased brain. J Cell Mol Med 2008; 12:1872-84. [PMID: 18363840 PMCID: PMC4506157 DOI: 10.1111/j.1582-4934.2008.00315.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Rather different from their initial image as passive supportive cells of the CNS, the astrocytes are now considered as active partners at synapses, able to release a set of gliotransmitter-like substances to modulate synaptic communication within neuronal networks. Whereas glutamate and ATP were first regarded as main determinants of gliotransmission, growing evidence indicates now that the amino acid D-serine is another important player in the neuronal-glial dialogue. Through the regulation of glutamatergic neurotransmission through both N-methyl-D-aspartate (NMDA-R) and non-NMDA-R, D-serine is helping in modelling the appropriate connections in the developing brain and influencing the functional plasticity within neuronal networks throughout lifespan. The understanding of D-serine signalling, which has increased linearly in the last few years, gives new insights into the critical role of impaired neuronal-glial communication in the diseased brain, and offers new opportunities for developing relevant strategies to treat cognitive deficits associated to brain disorders.
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Affiliation(s)
- J-M Billard
- Centre de Psychiatrie et Neurosciences, INSERM UMR 894, Paris F-75014, France.
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Fiacco TA, Agulhon C, Taves SR, Petravicz J, Casper KB, Dong X, Chen J, McCarthy KD. Selective stimulation of astrocyte calcium in situ does not affect neuronal excitatory synaptic activity. Neuron 2007; 54:611-26. [PMID: 17521573 DOI: 10.1016/j.neuron.2007.04.032] [Citation(s) in RCA: 240] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 03/09/2007] [Accepted: 04/27/2007] [Indexed: 11/16/2022]
Abstract
Astrocytes are considered the third component of the synapse, responding to neurotransmitter release from synaptic terminals and releasing gliotransmitters--including glutamate--in a Ca(2+)-dependent manner to affect neuronal synaptic activity. Many studies reporting astrocyte-driven neuronal activity have evoked astrocyte Ca(2+) increases by application of endogenous ligands that directly activate neuronal receptors, making astrocyte contribution to neuronal effect(s) difficult to determine. We have made transgenic mice that express a Gq-coupled receptor only in astrocytes to evoke astrocyte Ca(2+) increases using an agonist that does not bind endogenous receptors in brain. By recording from CA1 pyramidal cells in acute hippocampal slices from these mice, we demonstrate that widespread Ca(2+) elevations in 80%-90% of stratum radiatum astrocytes do not increase neuronal Ca(2+), produce neuronal slow inward currents, or affect excitatory synaptic activity. Our findings call into question the developing consensus that Ca(2+)-dependent glutamate release by astrocytes directly affects neuronal synaptic activity in situ.
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Affiliation(s)
- Todd A Fiacco
- Department of Pharmacology, 1004 Mary Ellen Jones Building CB# 7365, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7365, USA
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Rutter AR, Fradley RL, Garrett EM, Chapman KL, Lawrence JM, Rosahl TW, Patel S. Evidence from gene knockout studies implicates Asc-1 as the primary transporter mediating d-serine reuptake in the mouse CNS. Eur J Neurosci 2007; 25:1757-66. [PMID: 17432963 DOI: 10.1111/j.1460-9568.2007.05446.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the mammalian central nervous system, transporter-mediated reuptake may be critical for terminating the neurotransmitter action of D-serine at the strychnine insensitive glycine site of the NMDA receptor. The Na(+) independent amino acid transporter alanine-serine-cysteine transporter 1 (Asc-1) has been proposed to account for synaptosomal d-serine uptake by virtue of its high affinity for D-serine and widespread neuronal expression throughout the brain. Here, we sought to validate the contribution of Asc-1 to D-serine uptake in mouse brain synaptosomes using Asc-1 gene knockout (KO) mice. Total [(3)H]D-serine uptake in forebrain and cerebellar synaptosomes from Asc-1 knockout mice was reduced to 34 +/- 5% and 22 +/- 3% of that observed in wildtype (WT) mice, respectively. When the Na(+) dependent transport components were removed by omission of Na(+) ions in the assay buffer, D-serine uptake in knockout mice was reduced to 8 +/- 1% and 3 +/- 1% of that measured in wildtype mice in forebrain and cerebellum, respectively, suggesting Asc-1 plays a major role in the Na(+) independent transport of D-serine. Potency determination of D-serine uptake showed that Asc-1 mediated rapid high affinity Na(+) independent uptake with an IC(50) of 19 +/- 1 microm. The remaining uptake was mediated predominantly via a low affinity Na(+) dependent transporter with an IC(50) of 670 +/- 300 microm that we propose is the glial alanine-serine-cysteine transporter 2 (ASCT2) transporter. The results presented reveal that Asc-1 is the only high affinity D-serine transporter in the mouse CNS and is the predominant mechanism for D-serine reuptake.
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Affiliation(s)
- A Richard Rutter
- Department of Molecular and Cellular Neuroscience, Merck Sharp and Dohme Research Laboratories, The Neuroscience Research Centre, Terlings Park, Harlow, Essex, UK.
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Bergeron R, Imamura Y, Frangioni JV, Greene RW, Coyle JT. Endogenous N-acetylaspartylglutamate reduced NMDA receptor-dependent current neurotransmission in the CA1 area of the hippocampus. J Neurochem 2007; 100:346-57. [PMID: 17241157 DOI: 10.1111/j.1471-4159.2006.04253.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-Acetylaspartylglutamate (NAAG) is a neuropeptide found in high concentrations in the brain. Using whole-cell recordings of CA1 pyramidal neurons in acute hippocampal slices, we found that either (i) the application of exogenous NAAG or (ii) an increase of endogenous extracellular NAAG, caused by the inhibition of its catabolic enzyme glutamate carboxypeptidase II (GCP II), resulted in a significant reduction in the amplitude of the isolated NMDA receptor (NMDAR) component of the evoked excitatory postsynaptic current (EPSC). Conversely, reduction of endogenous extracellular NAAG caused by either (i) perfusion with a soluble form of pure human GCP II or (ii) affinity purified antibodies against NAAG, enhanced the amplitude of the isolated NMDAR current. Bath application of GCP II inhibitor induced a progressive loss of spontaneous NMDAR miniatures. Furthermore, NAAG blocked the induction of long-term potentiation at Schaffer collateral axons-CA1 pyramidal neuron synapses. All together, these results suggest that NAAG acts as an endogenous modulator of NMDARs in the CA1 area of the hippocampus.
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Affiliation(s)
- Richard Bergeron
- Ottawa Health Research Institute, Department of Psychiatry, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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45
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Le Meur K, Galante M, Angulo MC, Audinat E. Tonic activation of NMDA receptors by ambient glutamate of non-synaptic origin in the rat hippocampus. J Physiol 2006; 580:373-83. [PMID: 17185337 PMCID: PMC2075557 DOI: 10.1113/jphysiol.2006.123570] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In several neuronal types of the CNS, glutamate and GABA receptors mediate a persistent current which reflects the presence of a low concentration of transmitters in the extracellular space. Here, we further characterize the tonic current mediated by ambient glutamate in rat hippocampal slices. A tonic current of small amplitude (53.99 +/- 6.48 pA at +40 mV) with the voltage dependency and the pharmacology of NMDA receptors (NMDARs) was detected in virtually all pyramidal cells of the CA1 and subiculum areas. Manipulations aiming at increasing D-serine or glycine extracellular concentrations failed to modify this current indicating that the glycine binding sites of the NMDARs mediating the tonic current were saturated. In contrast, non-transportable inhibitors of glutamate transporters increased the amplitude of this tonic current, indicating that the extracellular concentration of glutamate primarily regulates its magnitude. Neither AMPA/kainate receptors nor metabotropic glutamate receptors contributed significantly to this tonic excitation of pyramidal neurons. In the presence of glutamate transporter inhibitors, however, a significant proportion of the tonic conductance was mediated by AMPA receptors. The tonic current was unaffected when inhibiting vesicular release of transmitters from neurons but was increased upon inhibition of the enzyme converting glutamate in glutamine in glial cells. These observations indicate that ambient glutamate is mainly of glial origin. Finally, experiments with the use-dependent antagonist MK801 indicated that NMDARs mediating the tonic conductance are probably extra-synaptic NMDARs.
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Affiliation(s)
- Karim Le Meur
- Inserm U603, Université Paris Descartes, 45 rue des Saints Pères, 75006 Paris, France
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46
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Junjaud G, Rouaud E, Turpin F, Mothet JP, Billard JM. Age-related effects of the neuromodulator D-serine on neurotransmission and synaptic potentiation in the CA1 hippocampal area of the rat. J Neurochem 2006; 98:1159-66. [PMID: 16790028 DOI: 10.1111/j.1471-4159.2006.03944.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effects of the co-agonist of the N-methyl-D-aspartate receptor (NMDAr) D-serine on glutamatergic neurotransmission and synaptic potentiation were studied in the CA1 hippocampal field of young (3-5 months old) and aged (25-27 months old) Sprague-Dawley rats using ex vivo extracellular electrophysiological recording techniques. Exogenous d-serine depressed fast neurotransmission mediated by the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate subtype of glutamate receptors in young but not in aged rats by acting on inhibitory glycinergic interneurons. In contrast, D-serine dose-dependently enhanced NMDAr-mediated synaptic responses in both groups of animals, but with a larger magnitude in aged rats, thus preventing the age-related decrease in NMDAr activation. D-serine also increased the magnitude of long-term potentiation in aged but not in young rats. Finally, D-serine levels were dramatically reduced in hippocampal tissues of aged rats. Taken together, these results indicate a weaker activation of the NMDAr glycine modulatory site by endogenous D-serine in aged animals, which accounts for a reduced NMDAr contribution to synaptic plasticity in ageing.
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Affiliation(s)
- G Junjaud
- Neurobiologie de la Croissance et de la Sénescence, INSERM, Faculté de Médecine, Université Paris-Descartes, Paris, France
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47
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Mothet JP, Rouaud E, Sinet PM, Potier B, Jouvenceau A, Dutar P, Videau C, Epelbaum J, Billard JM. A critical role for the glial-derived neuromodulator D-serine in the age-related deficits of cellular mechanisms of learning and memory. Aging Cell 2006; 5:267-74. [PMID: 16842499 DOI: 10.1111/j.1474-9726.2006.00216.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Age-associated deficits in learning and memory are closely correlated with impairments of synaptic plasticity. Analysis of N-methyl-D-aspartate receptor (NMDAr)-dependent long-term potentiation (LTP) in CA1 hippocampal slices indicates that the glial-derived neuromodulator D-serine is required for the induction of synaptic plasticity. During aging, the content of D-serine and the expression of its synthesizing enzyme serine racemase are significantly decreased in the hippocampus. Impaired LTP and NMDAr-mediated synaptic potentials in old rats are rescued by exogenous D-serine. These results highlight the critical role of glial cells and presumably astrocytes, through the availability of D-serine, in the deficits of synaptic mechanisms of learning and memory that occur in the course of aging.
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Affiliation(s)
- J P Mothet
- Neurobiologie de la Croissance et de la Sénescence, UMR 549 INSERM, Faculté de Médecine, Université Paris-Descartes, 2 ter rue d'Alésia, 75014 Paris, France
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Guo JD, Wang H, Zhang YQ, Zhao ZQ. Distinct effects of D-serine on spinal nociceptive responses in normal and carrageenan-injected rats. Biochem Biophys Res Commun 2006; 343:401-6. [PMID: 16546123 DOI: 10.1016/j.bbrc.2006.02.156] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Accepted: 02/25/2006] [Indexed: 11/30/2022]
Abstract
Single unit extracellular recordings from dorsal horn neurons were performed with glass micropipettes in pentobarbital-anesthetized rats. A total of 60 wide dynamic range (WDR) neurons were obtained from 34 rats. In normal rats (20/34), spinally administered D-serine (10 nmol), a putative endogenous agonist of glycine site of NMDA receptors, significantly enhanced the C- but not Abeta-, and Adelta-fiber responses of WDR neurons in the spinal dorsal horn. When 1 nmol of the glycine site antagonist 7-chlorokynurenic acid (7-CK) was co-administered with 10 nmol D-serine, the facilitation of D-serine on C-fiber response was completely blocked. 7-CK (1 nmol) alone failed to influence Abeta-, Adelta-, and C-fiber responses of WDR neurons. In contrast, in carrageenan-injected rats (14/34), 10 nmol D-serine had no effect on C-fiber response, while 1 nmol 7-CK per se markedly depressed C-fiber response of WDR neurons. These findings suggest that under physiological conditions, glycine sites in the spinal cord were available but became saturated following peripheral inflammation. Thus, increased endogenous d-serine or glycine may be involved in nociceptive transmission by modulating NMDA receptor activities. The glycine site of NMDA receptors may become a target for the prevention of inflammatory pain.
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Affiliation(s)
- Ji-Dong Guo
- Institute of Neurobiology, Fudan University, Shanghai 200433, China
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Ren WH, Guo JD, Cao H, Wang H, Wang PF, Sha H, Ji RR, Zhao ZQ, Zhang YQ. Is endogenous d-serine in the rostral anterior cingulate cortex necessary for pain-related negative affect? J Neurochem 2006; 96:1636-47. [PMID: 16476080 DOI: 10.1111/j.1471-4159.2006.03677.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Functional activation of NMDA receptors requires co-activation of glutamate- and glycine-binding sites. D-serine is considered to be an endogenous ligand for the glycine site of NMDA receptors. Using a combination of a rat formalin-induced conditioned place avoidance (F-CPA) behavioral model and whole-cell patch-clamp recording in rostral anterior cingulate cortex (rACC) slices, we examined the effects of d-amino acid oxidase (DAAO), an endogenous D-serine-degrading enzyme, and 7-chlorokynurenate (7Cl-KYNA), an antagonist of the glycine site of NMDA receptors, on pain-related aversion. Degradation of endogenous D-serine with DAAO, or selective blockade of the glycine site of NMDA receptors by 7Cl-KYNA, effectively inhibited NMDA-evoked currents in rACC slices. Intra-rACC injection of DAAO (0.1 U) and 7Cl-KYNA (2 and 0.2 mM, 0.6 microL per side) 20 min before F-CPA conditioning greatly attenuated F-CPA scores, but did not affect formalin-induced acute nociceptive behaviors and electric foot shock-induced conditioned place avoidance. This study reveals for the first time that endogenous D-serine plays a critical role in pain-related aversion by activating the glycine site of NMDA receptors in the rACC. Furthermore, these results extend our hypothesis that activation of NMDA receptors in the rACC is necessary for the acquisition of specific pain-related negative emotion. Thus a new and promising strategy for the prevention of chronic pain-induced emotional disturbance might be raised.
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Affiliation(s)
- Wen-Hua Ren
- Institutes of Brain Science, Institute of Neurobiology [corrected] Fudan University, Shanghai, China
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Avignone E, Frenguelli BG, Irving AJ. Differential responses to NMDA receptor activation in rat hippocampal interneurons and pyramidal cells may underlie enhanced pyramidal cell vulnerability. Eur J Neurosci 2005; 22:3077-90. [PMID: 16367774 DOI: 10.1111/j.1460-9568.2005.04497.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hippocampal interneurons are generally more resistant than pyramidal cells to excitotoxic insults. Because NMDA receptors play a crucial role in neurodegeneration, we have compared the response to exogenous NMDA in CA1 pyramidal cells and interneurons of the stratum oriens using combined whole-cell patch-clamp recording and ratiometric Ca2+ imaging. In voltage-clamp, current-clamp or in nominally Mg2+-free medium, NMDA (10 microM; 3-5 min exposure in the presence of tetrodotoxin) induced a markedly larger inward current and Ca2+ rise in pyramidal cells than in interneurons. Pyramidal cells also showed a more pronounced voltage dependence in their response to NMDA. We hypothesized that this enhanced response to NMDA receptor activation in pyramidal cells could underlie their increased vulnerability to excitotoxicity. Using loss of dye as an indicator of degenerative membrane disruption, interneurons tolerated continuous exposure to a high concentration of NMDA (30 microM) for longer periods than pyramidal cells. This acute neurodegeneration in pyramidal cells was independent of intracellular Ca2+, because high intracellular BAPTA (20 mM) did not prolong survival time. Thus, a plausible explanation for the enhanced sensitivity of pyramidal neurons to excitotoxic insults associated with cerebral ischemia is their greater response to NMDA receptor activation, which may reflect differences in NMDA receptor expression and/or subunit composition.
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Affiliation(s)
- E Avignone
- Neurosciences Institute, Division of Pathology & Neuroscience, University of Dundee, Ninewells Hospital, Dundee, UK DD1 9SY.
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