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Oliveira-Lima OC, de Carvalho GA, do Prado Assunção L, Bailão AM, Ulrich H, Marques BL, de Oliveira ACP, Gomez RS, Pinto MCX. GlyT1 Inhibition by NFPS Promotes Neuroprotection in Amyloid-β-Induced Alzheimer's Disease Animal Model. Neurochem Res 2024:10.1007/s11064-024-04190-0. [PMID: 38888830 DOI: 10.1007/s11064-024-04190-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 04/29/2024] [Accepted: 06/03/2024] [Indexed: 06/20/2024]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β, leading to N-methyl-D-aspartate (NMDA) receptor-dependent synaptic depression, spine elimination, and memory deficits. Glycine transporter type 1 (GlyT1) modulates glutamatergic neurotransmission via NMDA receptors (NMDAR), presenting a potential alternative therapeutic approach for AD. This study investigates the neuroprotective potential of GlyT1 inhibition in an amyloid-β-induced AD mouse model. C57BL/6 mice were treated with N-[3-([1,1-Biphenyl]-4-yloxy)-3-(4-fluorophenyl)propyl]-N-methylglycine (NFPS), a GlyT1 inhibitor, 24 h prior to intrahippocampal injection of amyloid-β. NFPS pretreatment prevented amyloid-β-induced cognitive deficits in short-term and long-term memory, evidenced by novel object recognition and spatial memory tasks. Moreover, NFPS pretreatment curbed microglial activation, astrocytic reactivity, and subsequent neuronal damage from amyloid-β injection. An extensive label-free quantitative UPLC-MSE proteomic analysis was performed on the hippocampi of mice treated with NFPS. In proteomics, KEGG enrichment analysis revealed increased in dopaminergic synapse, purine-containing compound biosynthetic process and long-term potentiation, and a reduction in Glucose catabolic process and glycolytic process pathways. The western blot analysis confirmed that NFPS treatment elevated BDNF levels, correlating with enhanced TRKB phosphorylation and mTOR activation. Moreover, NFPS treatment reduced the GluN2B expression after 6 h, which was associated with an increase on CaMKIV and CREB phosphorylation. Collectively, these findings demonstrate that GlyT1 inhibition by NFPS activates diverse neuroprotective pathways, enhancing long-term potentiation signaling and countering amyloid-β-induced hippocampal damage.
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Affiliation(s)
- Onésia Cristina Oliveira-Lima
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Gustavo Almeida de Carvalho
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Leandro do Prado Assunção
- Departamento de Bioquímica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, CEP 74690-900, Brazil
| | - Alexandre Melo Bailão
- Departamento de Bioquímica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia-GO, CEP 74690-900, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Bruno Lemes Marques
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil
| | - Antônio Carlos Pinheiro de Oliveira
- Departamento de Farmacologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, Belo Horizonte-MG, 6627, 31270-901, Brazil
| | - Renato Santiago Gomez
- Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Av. Alfredo Balena, 190, Belo Horizonte-MG, 30130-100, Brazil
| | - Mauro Cunha Xavier Pinto
- Laboratório de Neuroquímica e Neurofarmacologia Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança, S/N, UFG, Prédio ICB II, Sala 114, Goiânia-GO, CEP 74690-900, Brazil.
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Ireton KE, Xing X, Kim K, Weiner JC, Jacobi AA, Grover A, Foote M, Ota Y, Berman R, Hanks T, Hell JW. Regulation of the Ca 2+ Channel Ca V1.2 Supports Spatial Memory and Its Flexibility and LTD. J Neurosci 2023; 43:5559-5573. [PMID: 37419689 PMCID: PMC10376936 DOI: 10.1523/jneurosci.1521-22.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 04/30/2023] [Accepted: 05/15/2023] [Indexed: 07/09/2023] Open
Abstract
Widespread release of norepinephrine (NE) throughout the forebrain fosters learning and memory via adrenergic receptor (AR) signaling, but the molecular mechanisms are largely unknown. The β2 AR and its downstream effectors, the trimeric stimulatory Gs-protein, adenylyl cyclase (AC), and the cAMP-dependent protein kinase A (PKA), form a unique signaling complex with the L-type Ca2+ channel (LTCC) CaV1.2. Phosphorylation of CaV1.2 by PKA on Ser1928 is required for the upregulation of Ca2+ influx on β2 AR stimulation and long-term potentiation induced by prolonged theta-tetanus (PTT-LTP) but not LTP induced by two 1-s-long 100-Hz tetani. However, the function of Ser1928 phosphorylation in vivo is unknown. Here, we show that S1928A knock-in (KI) mice of both sexes, which lack PTT-LTP, express deficiencies during initial consolidation of spatial memory. Especially striking is the effect of this mutation on cognitive flexibility as tested by reversal learning. Mechanistically, long-term depression (LTD) has been implicated in reversal learning. It is abrogated in male and female S1928A knock-in mice and by β2 AR antagonists and peptides that displace β2 AR from CaV1.2. This work identifies CaV1.2 as a critical molecular locus that regulates synaptic plasticity, spatial memory and its reversal, and LTD.SIGNIFICANCE STATEMENT We show that phosphorylation of the Ca2+ channel CaV1.2 on Ser1928 is important for consolidation of spatial memory and especially its reversal, and long-term depression (LTD). Identification of Ser1928 as critical for LTD and reversal learning supports the model that LTD underlies flexibility of reference memory.
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Affiliation(s)
- Kyle E Ireton
- Department of Pharmacology, University of California, Davis, California 95616-8636
- Center for Neuroscience, University of California, Davis, California 95616-8636
| | - Xiaoming Xing
- Department of Pharmacology, University of California, Davis, California 95616-8636
| | - Karam Kim
- Department of Pharmacology, University of California, Davis, California 95616-8636
| | - Justin C Weiner
- Department of Pharmacology, University of California, Davis, California 95616-8636
| | - Ariel A Jacobi
- Department of Pharmacology, University of California, Davis, California 95616-8636
| | - Aarushi Grover
- Department of Pharmacology, University of California, Davis, California 95616-8636
| | - Molly Foote
- Center for Neuroscience, University of California, Davis, California 95616-8636
| | - Yusuke Ota
- Center for Neuroscience, University of California, Davis, California 95616-8636
| | - Robert Berman
- Center for Neuroscience, University of California, Davis, California 95616-8636
| | - Timothy Hanks
- Center for Neuroscience, University of California, Davis, California 95616-8636
- Department of Neurology, University of California, Davis, California 95616-8636
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, California 95616-8636
- Center for Neuroscience, University of California, Davis, California 95616-8636
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3
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Woolrych A, Vautrelle N, Reynolds JNJ, Parr-Brownlie LC. Throwing open the doors of perception: The role of dopamine in visual processing. Eur J Neurosci 2021; 54:6135-6146. [PMID: 34340265 DOI: 10.1111/ejn.15408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 07/05/2021] [Accepted: 07/18/2021] [Indexed: 01/11/2023]
Abstract
Animals form associations between visual cues and behaviours. Although dopamine is known to be critical in many areas of the brain to bind sensory information with appropriate responses, dopamine's role in the visual system is less well understood. Visual signals, which indicate the likely occurrence of a rewarding or aversive stimulus or indicate the context within which such stimuli may arrive, modulate activity in the superior colliculus and alter behaviour. However, such signals primarily originate in cortical and basal ganglia circuits, and evidence of direct signalling from midbrain dopamine neurons to superior colliculus is lacking. Instead, hypothalamic A13 dopamine neurons innervate the superior colliculus, and dopamine receptors are differentially expressed in the superior colliculus, with D1 receptors in superficial layers and D2 receptors in deep layers. However, it remains unknown if A13 dopamine neurons control behaviours through their effect on afferents within the superior colliculus. We propose that A13 dopamine neurons may play a critical role in processing information in the superior colliculus, modifying behavioural responses to visual cues, and propose some testable hypotheses regarding dopamine's effect on visual perception.
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Affiliation(s)
- Alexander Woolrych
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Nicolas Vautrelle
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - John N J Reynolds
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Louise C Parr-Brownlie
- Department of Anatomy, School of Biomedical Sciences, Brain Health Research Centre, University of Otago, Dunedin, New Zealand
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4
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Johnson KO, Triplett JW. Wiring subcortical image-forming centers: Topography, laminar targeting, and map alignment. Curr Top Dev Biol 2020; 142:283-317. [PMID: 33706920 DOI: 10.1016/bs.ctdb.2020.10.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Efficient sensory processing is a complex and important function for species survival. As such, sensory circuits are highly organized to facilitate rapid detection of salient stimuli and initiate motor responses. For decades, the retina's projections to image-forming centers have served as useful models to elucidate the mechanisms by which such exquisite circuitry is wired. In this chapter, we review the roles of molecular cues, neuronal activity, and axon-axon competition in the development of topographically ordered retinal ganglion cell (RGC) projections to the superior colliculus (SC) and dorsal lateral geniculate nucleus (dLGN). Further, we discuss our current state of understanding regarding the laminar-specific targeting of subclasses of RGCs in the SC and its homolog, the optic tectum (OT). Finally, we cover recent studies examining the alignment of projections from primary visual cortex with RGCs that monitor the same region of space in the SC.
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Affiliation(s)
- Kristy O Johnson
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC, United States; Institute for Biomedical Sciences, The George Washington University School of Medicine, Washington, DC, United States
| | - Jason W Triplett
- Center for Neuroscience Research, Children's National Research Institute, Washington, DC, United States; Department of Pediatrics, The George Washington University School of Medicine, Washington, DC, United States.
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5
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Metzbower SR, Joo Y, Benavides DR, Blanpied TA. Properties of Individual Hippocampal Synapses Influencing NMDA-Receptor Activation by Spontaneous Neurotransmission. eNeuro 2019; 6:ENEURO.0419-18.2019. [PMID: 31110134 PMCID: PMC6541874 DOI: 10.1523/eneuro.0419-18.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/05/2019] [Accepted: 05/12/2019] [Indexed: 12/14/2022] Open
Abstract
NMDA receptor (NMDAR) activation is critical for maintenance and modification of synapse strength. Specifically, NMDAR activation by spontaneous glutamate release has been shown to mediate some forms of synaptic plasticity as well as synaptic development. Interestingly, there is evidence that within individual synapses each release mode may be segregated such that postsynaptically there are distinct pools of responsive receptors. To examine potential regulators of NMDAR activation because of spontaneous glutamate release in cultured hippocampal neurons, we used GCaMP6f imaging at single synapses in concert with confocal and super-resolution imaging. Using these single-spine approaches, we found that Ca2+ entry activated by spontaneous release tends to be carried by GluN2B-NMDARs. Additionally, the amount of NMDAR activation varies greatly both between synapses and within synapses, and is unrelated to spine and synapse size, but does correlate loosely with synapse distance from the soma. Despite the critical role of spontaneous activation of NMDARs in maintaining synaptic function, their activation seems to be controlled factors other than synapse size or synapse distance from the soma. It is most likely that NMDAR activation by spontaneous release influenced variability in subsynaptic receptor position, release site position, vesicle content, and channel properties. Therefore, spontaneous activation of NMDARs appears to be regulated distinctly from other receptor types, notably AMPARs, within individual synapses.
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Affiliation(s)
| | - Yuyoung Joo
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland, 21201
| | - David R Benavides
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland, 21201
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6
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Yee CW, Ivanova E, Toychiev AH, Willis DE, Sagdullaev BT. Atypical Expression and Activation of GluN2A- and GluN2B-Containing NMDA Receptors at Ganglion Cells during Retinal Degeneration. Neuroscience 2018; 393:61-72. [PMID: 30312782 DOI: 10.1016/j.neuroscience.2018.09.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/21/2018] [Accepted: 09/30/2018] [Indexed: 11/26/2022]
Abstract
Cellular communication through chemical synapses is determined by the nature of the neurotransmitter and the composition of postsynaptic receptors. In the excitatory synapse between bipolar and ganglion cells of the retina, postsynaptic AMPA receptors mediate resting activity. During evoked response, however, more abundant and sustained levels of glutamate also activate GluN2B-containing NMDA receptors (NMDARs). This phasic recruitment of distinct glutamate receptors is essential for visual discrimination; however, the fidelity of this basic mechanism under elevated glutamate levels due to aberrant activity, a common pathophysiology, is not known. Here, in both male and female mice with retinal degeneration (rd10), a condition associated with elevated synaptic activity, we reveal that changes in synaptic input to ganglion cells altered both composition and activation of NMDARs. We found that, in contrast to wild type, the spontaneous activity of rd10 cells was largely NMDAR-dependent. Surprisingly, this activity was driven primarily by atypical activation of GluN2A -containing NMDARs, not GluN2B-NMDARs. Indeed, immunohistochemical analyses and Western blot showed greater levels of the GluN2A-NMDAR subunit expression in rd10 retina compared to wild type. Overall, these results demonstrate how aberrant signaling leads to pathway-specific alterations in NMDAR expression and function.
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Affiliation(s)
- Christopher W Yee
- Weill Cornell Medicine at Burke Neurological Institute, White Plains, NY 10605, United States
| | - Elena Ivanova
- Weill Cornell Medicine at Burke Neurological Institute, White Plains, NY 10605, United States
| | - Abduqodir H Toychiev
- Weill Cornell Medicine at Burke Neurological Institute, White Plains, NY 10605, United States
| | - Dianna E Willis
- Weill Cornell Medicine at Burke Neurological Institute, White Plains, NY 10605, United States
| | - Botir T Sagdullaev
- Weill Cornell Medicine at Burke Neurological Institute, White Plains, NY 10605, United States.
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7
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Sun W, Hansen KB, Jahr CE. Allosteric Interactions between NMDA Receptor Subunits Shape the Developmental Shift in Channel Properties. Neuron 2017; 94:58-64.e3. [PMID: 28384476 DOI: 10.1016/j.neuron.2017.03.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/03/2017] [Accepted: 03/10/2017] [Indexed: 11/15/2022]
Abstract
During development of the central nervous system, there is a shift in the subunit composition of NMDA receptors (NMDARs) resulting in a dramatic acceleration of NMDAR-mediated synaptic currents. This shift coincides with upregulation of the GluN2A subunit and triheteromeric GluN1/2A/2B receptors with fast deactivation kinetics, whereas expression of diheteromeric GluN1/2B receptors with slower deactivation kinetics is decreased. Here, we show that allosteric interactions occur between the glutamate-binding GluN2 subunits in triheteromeric GluN1/2A/2B NMDARs. This allosterism is dominated by the GluN2A subunit and results in functional properties not predicted by those of diheteromeric GluN1/2A and GluN1/2B NMDARs. These findings suggest that GluN1/2A/2B NMDARs may maintain some signaling properties of the GluN2B subunit while having the kinetic properties of GluN1/2A NMDARs and highlight the complexity in NMDAR signaling created by diversity in subunit composition.
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Affiliation(s)
- Weinan Sun
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA
| | - Kasper B Hansen
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, 32 Campus Dr., Missoula, MT 59812, USA
| | - Craig E Jahr
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA.
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8
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Pan L, Yang J, Yang Q, Wang X, Zhu L, Liu Y, Lou H, Xu C, Shen Y, Wang H. A Critical Period for the Rapid Modification of Synaptic Properties at the VPm Relay Synapse. Front Mol Neurosci 2017; 10:238. [PMID: 28790892 PMCID: PMC5525376 DOI: 10.3389/fnmol.2017.00238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 07/12/2017] [Indexed: 01/28/2023] Open
Abstract
In addition to cortical areas, the thalamus also displays plasticity during a critical period in early life. Since most sensory information is transmitted to the cortex via the thalamus, it will be of significant interest to understand the precise time window and underlying mechanisms of this critical period in the thalamus. By using in vitro whole-cell patch recording in acute brain slices, we found that VPm relay synapses were only sensitive to whisker deprivation from postnatal day 11 (P11) to P14. Whisker deprivation initiated within the P11 to P14 window significantly reduced the amplitude of AMPAR-EPSCs, but not NMDAR-EPSCs when recorded 24 h after whisker removal. From P10 to P11, the timing for entry into the critical period and the kinetics underlying NMDAR-EPSCs function were significantly altered. At P11, NMDAR-EPSCs were less sensitive to ifenprodil, a selective blocker of NR2B-containing NMDAR, and the protein level of NR2A was significantly increased compared to those at P10. At the end of the critical period there were no obvious changes in synaptic properties when compared between P14 and P15. Using calcium imaging, we found that fewer P15 VPm neurons could be excited by the GABAa receptor agonist, muscimol, when compared to P14 VPm neurons; this correlated to an increase in KCC2 expression. Our studies revealed a precise critical period of sensory experience-dependent plasticity in the thalamus featuring distinct molecular mechanisms which occur at the start and end of this critical window.
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Affiliation(s)
- Libiao Pan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Junhua Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Qian Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Xiaomeng Wang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Liya Zhu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Yali Liu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Huifang Lou
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Chou Xu
- Nanlou Respiratory Diseases Department, Chinese PLA General HospitalBeijing, China
| | - Ying Shen
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China
| | - Hao Wang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Key Laboratory of Neurobiology, Zhejiang University School of MedicineHangzhou, China.,Second Affiliated Hospital, Zhejiang University School of MedicineHangzhou, China
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9
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Enhancing NMDA Receptor Function: Recent Progress on Allosteric Modulators. Neural Plast 2017; 2017:2875904. [PMID: 28163934 PMCID: PMC5253171 DOI: 10.1155/2017/2875904] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/16/2016] [Accepted: 12/13/2016] [Indexed: 12/28/2022] Open
Abstract
The N-methyl-D-aspartate receptors (NMDARs) are subtype glutamate receptors that play important roles in excitatory neurotransmission and synaptic plasticity. Their hypo- or hyperactivation are proposed to contribute to the genesis or progression of various brain diseases, including stroke, schizophrenia, depression, and Alzheimer's disease. Past efforts in targeting NMDARs for therapeutic intervention have largely been on inhibitors of NMDARs. In light of the discovery of NMDAR hypofunction in psychiatric disorders and perhaps Alzheimer's disease, efforts in boosting NMDAR activity/functions have surged in recent years. In this review, we will focus on enhancing NMDAR functions, especially on the recent progress in the generation of subunit-selective, allosteric positive modulators (PAMs) of NMDARs. We shall also discuss the usefulness of these newly developed NMDAR-PAMs.
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The Functional and Molecular Properties, Physiological Functions, and Pathophysiological Roles of GluN2A in the Central Nervous System. Mol Neurobiol 2016; 54:1008-1021. [DOI: 10.1007/s12035-016-9715-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/11/2016] [Indexed: 11/25/2022]
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11
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Papouin T, Oliet SHR. Organization, control and function of extrasynaptic NMDA receptors. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130601. [PMID: 25225095 DOI: 10.1098/rstb.2013.0601] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
N-methyl D-aspartate receptors (NMDARs) exist in different forms owing to multiple combinations of subunits that can assemble into a functional receptor. In addition, they are located not only at synapses but also at extrasynaptic sites. There has been intense speculation over the past decade about whether specific NMDAR subtypes and/or locations are responsible for inducing synaptic plasticity and excitotoxicity. Here, we review the latest findings on the organization, subunit composition and endogenous control of NMDARs at extrasynaptic sites and consider their putative functions. Because astrocytes are capable of controlling NMDARs through the release of gliotransmitters, we also discuss the role of the glial environment in regulating the activity of these receptors.
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Affiliation(s)
- Thomas Papouin
- Neuroscience Department, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Stéphane H R Oliet
- Neurocentre Magendie, Inserm U862, Bordeaux, France Université de Bordeaux, Bordeaux, France
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12
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Tamminga CA, Zukin RS. Schizophrenia: Evidence implicating hippocampal GluN2B protein and REST epigenetics in psychosis pathophysiology. Neuroscience 2015. [PMID: 26211447 DOI: 10.1016/j.neuroscience.2015.07.038] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The hippocampus is strongly implicated in the psychotic symptoms of schizophrenia. Functionally, basal hippocampal activity (perfusion) is elevated in schizophrenic psychosis, as measured with positron emission tomography (PET) and with magnetic resonance (MR) perfusion techniques, while hippocampal activation to memory tasks is reduced. Subfield-specific hippocampal molecular pathology exists in human psychosis tissue which could underlie this neuronal hyperactivity, including increased GluN2B-containing NMDA receptors in hippocampal CA3, along with increased postsynaptic density protein-95 (PSD-95) along with augmented dendritic spines on the pyramidal neuron apical dendrites. We interpret these observations to implicate a reduction in the influence of a ubiquitous gene repressor, repressor element-1 silencing transcription factor (REST) in psychosis; REST is involved in the age-related maturation of the NMDA receptor from GluN2B- to GluN2A-containing NMDA receptors through epigenetic remodeling. These CA3 changes in psychosis leave the hippocampus liable to pathological increases in neuronal activity, feedforward excitation and false memory formation, sometimes with psychotic content.
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Affiliation(s)
- C A Tamminga
- UT Southwestern Medical School, Dallas, TX, United States.
| | - R S Zukin
- Albert Einstein School of Medicine, New York, NY, United States
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13
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Li W, Ghose S, Gleason K, Begovic’ A, Perez J, Bartko J, Russo S, Wagner AD, Selemon L, Tamminga CA. Synaptic proteins in the hippocampus indicative of increased neuronal activity in CA3 in schizophrenia. Am J Psychiatry 2015; 172:373-82. [PMID: 25585032 PMCID: PMC4457341 DOI: 10.1176/appi.ajp.2014.14010123] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE In schizophrenia, hippocampal perfusion is increased and declarative memory function is degraded. Based on an a priori model of hippocampal dysfunction in schizophrenic psychosis, the authors postulated molecular and cellular changes in CA3 consistent with increased NMDA receptor signaling. METHOD Postmortem hippocampal subfield tissue (CA3, CA1) from subjects with schizophrenia and nonpsychiatric comparison subjects was analyzed using Western blotting and Golgi histochemistry to examine the hypothesized outcomes. RESULTS The GluN2B-containing NMDA receptors (GluN2B/GluN1) and their associated postsynaptic membrane protein PSD95 were both increased in schizophrenia in CA3 tissue, but not in CA1 tissue. Quantitative analyses of Golgi-stained hippocampal neurons showed an increase in spine density on CA3 pyramidal cell apical dendrites (stratum radiatum) and an increase in the number of thorny excrescences. CONCLUSIONS The hippocampal data are consistent with increased excitatory signaling in CA3 and/or with an elevation in silent synapses in CA3, a state that may contribute to an increase in long-term potentiation in CA3 with subsequent stimulation and "unsilencing." These changes are plausibly associated with increased associational activity in CA3, with degraded declarative memory function, and with formation of false memories with psychotic content. The influence of these hyperactive hippocampal projections on targets in the limbic neocortex could contribute to components of schizophrenia manifestations in other cerebral regions.
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Affiliation(s)
- Wei Li
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Subroto Ghose
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Kelly Gleason
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Anita Begovic’
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510
| | - Jessica Perez
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - John Bartko
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Scott Russo
- Neuroscience Department, Mount Sinai Medical School, NY NY 10029
| | - Anthony D. Wagner
- Department of Psychology and Neuroscience Program, Stanford University, Palo Alto, CA 94305
| | - Lynn Selemon
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06510
| | - Carol A. Tamminga
- Division of Translational Neuroscience in Schizophrenia, Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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14
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Glycine transporters type 1 inhibitor promotes brain preconditioning against NMDA-induced excitotoxicity. Neuropharmacology 2014; 89:274-81. [PMID: 25312280 DOI: 10.1016/j.neuropharm.2014.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 09/07/2014] [Accepted: 10/01/2014] [Indexed: 11/24/2022]
Abstract
Brain preconditioning is a protective mechanism, which can be activated by sub-lethal stimulation of the NMDA receptors (NMDAR) and be used to achieve neuroprotection against stroke and neurodegenerative diseases models. Inhibitors of glycine transporters type 1 modulate glutamatergic neurotransmission through NMDAR, suggesting an alternative therapeutic strategy of brain preconditioning. The aim of this work was to evaluate the effects of brain preconditioning induced by NFPS, a GlyT1 inhibitor, against NMDA-induced excitotoxicity in mice hippocampus, as well as to study its neurochemical mechanisms. C57BL/6 mice (male, 10-weeks-old) were preconditioned by intraperitoneal injection of NFPS at doses of 1.25, 2.5 or 5.0 mg/kg, 24 h before intrahippocampal injection of NMDA. Neuronal death was evaluated by fluoro jade C staining and neurochemical parameters were evaluated by gas chromatography-mass spectrometry, scintillation spectrometry and western blot. We observed that NFPS preconditioning reduced neuronal death in CA1 region of hippocampus submitted to NMDA-induced excitotoxicity. The amino acids (glycine and glutamate) uptake and content were increased in hippocampus of animals treated with NFPS 5.0 mg/kg, which were associated to an increased expression of type-2 glycine transporter (GlyT2) and glutamate transporters (EAAT1, EAAT2 and EAAT3). The expression of GlyT1 was reduced in animals treated with NFPS. Interestingly, the preconditioning reduced expression of GluN2B subunits of NMDAR, whereas did not change the expression of GluN1 or GluN2A in all tested doses. Our study suggests that NFPS preconditioning induces resistance against excitotoxicity, which is associated with neurochemical changes and reduction of GluN2B-containing NMDAR expression.
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15
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Pinto MCX, Simão F, da Costa FLP, Rosa DV, de Paiva MJN, Resende RR, Romano-Silva MA, Gomez MV, Gomez RS. Sarcosine preconditioning induces ischemic tolerance against global cerebral ischemia. Neuroscience 2014; 271:160-9. [PMID: 24797328 DOI: 10.1016/j.neuroscience.2014.04.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/09/2014] [Accepted: 04/24/2014] [Indexed: 02/01/2023]
Abstract
Brain ischemic tolerance is an endogenous protective mechanism activated by a preconditioning stimulus that is closely related to N-methyl-d-aspartate receptor (NMDAR). Glycine transporter type 1 (GlyT-1) inhibitors potentiate NMDAR and suggest an alternative strategy for brain preconditioning. The aim of this work was to evaluate the effects of brain preconditioning induced by sarcosine, a GlyT-1 inhibitor, against global cerebral ischemia and its relation to NMDAR. Sarcosine was administered over 7 days (300 or 500 mg/kg/day, ip) before the induction of a global cerebral ischemia model in Wistar rats (male, 8-week-old). It was observed that sarcosine preconditioning reduced cell death in rat hippocampi submitted to cerebral ischemia. Hippocampal levels of glycine were decreased in sarcosine-treated animals, which was associated with a reduction of [(3)H] glycine uptake and a decrease in glycine transporter expression (GlyT-1 and GlyT-2). The expression of glycine receptors and the NR1 and NR2A subunits of NMDAR were not affected by sarcosine preconditioning. However, sarcosine preconditioning reduced the expression of the NR2B subunits of NMDAR. In conclusion, these data demonstrate that sarcosine preconditioning induces ischemic tolerance against global cerebral ischemia and this neuroprotective state is associated with changes in glycine transport and reduction of NR2B-containing NMDAR expression.
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Affiliation(s)
- M C X Pinto
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil; Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil.
| | - F Simão
- Laboratório de Neurociências, Instituto de Pesquisas Biomédicas, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga 6690, 90610-000 Porto Alegre, RS, Brazil
| | - F L P da Costa
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil; Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil
| | - D V Rosa
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil
| | - M J N de Paiva
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - R R Resende
- Departamento de Bioquímica e Imunologia, Instituto de Ciência Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, 31270-901 Belo Horizonte, MG, Brazil
| | - M A Romano-Silva
- INCT de Medicina Molecular, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena 190, 30130-100 Belo Horizonte, MG, Brazil
| | - M V Gomez
- Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte, R. Domingos Vieira, 590, Belo Horizonte, MG, Brazil
| | - R S Gomez
- Departamento de Cirurgia, Faculdade de Medicina, Universidade Federal de Minas Gerais, Avenida Alfredo Balena, 190, 30130-100 Belo Horizonte, MG, Brazil.
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16
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Kannangara TS, Eadie BD, Bostrom CA, Morch K, Brocardo PS, Christie BR. GluN2A-/- Mice Lack Bidirectional Synaptic Plasticity in the Dentate Gyrus and Perform Poorly on Spatial Pattern Separation Tasks. Cereb Cortex 2014; 25:2102-13. [PMID: 24554729 DOI: 10.1093/cercor/bhu017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The different secondary subunits of the N-methyl-d-aspartate (NMDA) receptor each convey unique biophysical properties to the receptor complex, and may be key in determining the functional role played by NMDA receptors. In the hippocampus, the GluN2A and GluN2B subunits are particularly abundant; however, their exact roles in synaptic plasticity and behavior remain controversial. Here, we show that mice carrying a deletion for the GluN2A subunit (GluN2A(-/-)) demonstrate a severely compromised NMDA to AMPA receptor current ratio in granule cells from the dentate gyrus (DG), while granule cell morphology is unaltered. This deficit is accompanied by significant impairments in both LTP and LTD in the DG, whereas only minor impairments are observed in the CA1. In accordance with these hippocampal region-specific deficits, GluN2A(-/-) mice show impaired performance on the DG-associated task of spatial pattern separation. In contrast, GluN2A(-/-) mice show no deficit in temporal pattern separation, a process associated with CA1 functioning. Thus, our results establish the GluN2A subunit as a significant contributor to both bidirectional synaptic plasticity and spatial pattern separation in the DG.
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Affiliation(s)
- Timal S Kannangara
- Division of Medical Sciences Department of Cellular and Physiological Sciences Graduate Programs of Neuroscience and the Brain Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Brennan D Eadie
- Division of Medical Sciences Department of Cellular and Physiological Sciences Graduate Programs of Neuroscience and the Brain Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Crystal A Bostrom
- Division of Medical Sciences Department of Biology, University of Victoria, BC, Canada, V8P 5C2 and
| | | | | | - Brian R Christie
- Division of Medical Sciences Department of Biology, University of Victoria, BC, Canada, V8P 5C2 and Department of Cellular and Physiological Sciences Graduate Programs of Neuroscience and the Brain Research Centre, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
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17
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A Myosin Va mutant mouse with disruptions in glutamate synaptic development and mature plasticity in visual cortex. J Neurosci 2013; 33:8472-82. [PMID: 23658184 DOI: 10.1523/jneurosci.4585-12.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Myosin Va (MyoVa) mediates F-actin-based vesicular transport toward the plasma membrane and is found at neuronal postsynaptic densities (PSDs), but the role of MyoVa in synaptic development and function is largely unknown. Here, in studies using the dominant-negative MyoVa neurological mutant mouse Flailer, we find that MyoVa plays an essential role in activity-dependent delivery of PSD-95 and other critical PSD molecules to synapses and in endocytosis of AMPA-type glutamate receptors (AMPAR) in the dendrites of CNS neurons. MyoVa is known to carry a complex containing the major scaffolding proteins of the mature PSD, PSD-95, SAPAP1/GKAP, Shank, and Homer to dendritic spine synapses. In Flailer, neurons show abnormal dendritic shaft localization of PSD-95, stargazin, dynamin3, AMPARs and abnormal spine morphology. Flailer neurons also have abnormally high AMPAR miniature current frequencies and spontaneous AMPAR currents that are more frequent and larger than in wild-type while numbers of NMDAR containing synapses remain normal. The AMPAR abnormalities are consistent with a severely disrupted developmental regulation of long-term depression that we find in cortical Flailer neurons. Thus MyoVa plays a fundamentally important role both in localizing mature glutamate synapses to spines and in organizing the synapse for normal function. For this reason Flailer mice will be valuable in further dissecting the role of MyoVa in normal synaptic and circuit refinement and also in studies of neurological and neuropsychiatric diseases where disruptions of normal glutamate synapses are frequently observed.
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18
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Paoletti P, Bellone C, Zhou Q. NMDA receptor subunit diversity: impact on receptor properties, synaptic plasticity and disease. Nat Rev Neurosci 2013; 14:383-400. [DOI: 10.1038/nrn3504] [Citation(s) in RCA: 1525] [Impact Index Per Article: 138.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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19
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Siew WH, Tan KL, Babaei MA, Cheah PS, Ling KH. MicroRNAs and intellectual disability (ID) in Down syndrome, X-linked ID, and Fragile X syndrome. Front Cell Neurosci 2013; 7:41. [PMID: 23596395 PMCID: PMC3625835 DOI: 10.3389/fncel.2013.00041] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 03/27/2013] [Indexed: 01/01/2023] Open
Abstract
Intellectual disability (ID) is one of the many features manifested in various genetic syndromes leading to deficits in cognitive function among affected individuals. ID is a feature affected by polygenes and multiple environmental factors. It leads to a broad spectrum of affected clinical and behavioral characteristics among patients. Until now, the causative mechanism of ID is unknown and the progression of the condition is poorly understood. Advancement in technology and research had identified various genetic abnormalities and defects as the potential cause of ID. However, the link between these abnormalities with ID is remained inconclusive and the roles of many newly discovered genetic components such as non-coding RNAs have not been thoroughly investigated. In this review, we aim to consolidate and assimilate the latest development and findings on a class of small non-coding RNAs known as microRNAs (miRNAs) involvement in ID development and progression with special focus on Down syndrome (DS) and X-linked ID (XLID) [including Fragile X syndrome (FXS)].
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Affiliation(s)
- Wei-Hong Siew
- NeuroBiology and Genetics Group, Genetic Medicine Research Centre, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia UPM Serdang, Malaysia ; Clinical Genetics Unit, Department of Obstetrics and Gynaecology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia UPM Serdang, Malaysia
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20
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Abstract
Adolescent brain maturation is characterized by the emergence of executive function mediated by the prefrontal cortex, e.g., goal planning, inhibition of impulsive behavior and set shifting. Synaptic pruning of excitatory contacts is the signature morphologic event of late brain maturation during adolescence. Mounting evidence suggests that glutamate receptor-mediated synaptic plasticity, in particular long-term depression (LTD), is important for elimination of synaptic contacts in brain development. This review examines the possibility (1) that LTD mechanisms are enhanced in the prefrontal cortex during adolescence due to ongoing synaptic pruning in this late developing cortex and (2) that enhanced synaptic plasticity in the prefrontal cortex represents a key molecular substrate underlying the critical period for maturation of executive function. Molecular sites of interaction between environmental factors, such as alcohol and stress, and glutamate receptor mediated plasticity are considered. The accentuated negative impact of these factors during adolescence may be due in part to interference with LTD mechanisms that refine prefrontal cortical circuitry and when disrupted derail normal maturation of executive function. Diminished prefrontal cortical control over risk-taking behavior could further exacerbate negative outcomes associated with these behaviors, as for example addiction and depression. Greater insight into the neurobiology of the adolescent brain is needed to fully understand the molecular basis for heightened vulnerability during adolescence to the injurious effects of substance abuse and stress.
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Affiliation(s)
- L D Selemon
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520-8001, USA.
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21
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Sanders EM, Nguyen MA, Zhou KC, Hanks ME, Yusuf KA, Cox DN, Dumas TC. Developmental modification of synaptic NMDAR composition and maturation of glutamatergic synapses: matching postsynaptic slots with receptor pegs. THE BIOLOGICAL BULLETIN 2013; 224:1-13. [PMID: 23493503 DOI: 10.1086/bblv224n1p1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The numbers and types of ionotropic glutamate receptors at most vertebrate central excitatory synapses are altered as a function of changes in input activity patterns that occur during postnatal development. Activity-dependent developmental alterations in glutamate receptors underlie lasting changes in synaptic efficacy (plasticity) and metaplasticity (the plasticity of synaptic plasticity), which are critical elements of normal brain maturation. Understanding the specific involvement of glutamate receptors in synaptic development and function is made multiplicatively complex by the existence of a large number of glutamate receptor subunits, numerous subunit-specific amino acid sequences that regulate receptor function, and subunit-specific synaptic insertion restrictions imposed by associated anchoring proteins. Many receptor properties are altered when subunits are switched, so it is unclear which individual receptor property or properties underlie changes in synaptic function and plasticity during postnatal development. As a result, a more detailed understanding of the factors that regulate synaptic and cognitive development will involve mutations in glutamate receptor subunits that separate individual receptor properties and permit synaptic insertion at both immature and mature synapses in genetically modified organisms. This position paper focuses on structural modifications in N-methyl-d-aspartate receptors (NMDARs) that occur during postnatal forebrain development and attempts to provide a method for pursuing a more complete understanding of the functional ramifications of developmental alterations in NMDAR subunit composition.
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Affiliation(s)
- Erin M Sanders
- Molecular Neuroscience Department, Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA
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22
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Eye opening and PSD95 are required for long-term potentiation in developing superior colliculus. Proc Natl Acad Sci U S A 2012; 110:707-12. [PMID: 23267080 DOI: 10.1073/pnas.1215854110] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The only major glutamate receptor membrane-associated guanylate kinase scaffolds expressed in the young superficial superior colliculus (SC) are synapse-associated protein 102 (SAP102) and postsynaptic density protein 95 (PSD95). In this, as in all visual brain regions examined, synaptic PSD95 increases rapidly following simultaneous eyelid opening (EO). We show that EO and PSD95 are necessary for SC NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and this LTP is eliminated or reinstated by manipulating EO. PSD95 knockdown (KD) in vivo blocks this LTP, but not long-term depression, and reduces frequencies of miniature AMPA receptor and NMDAR currents with no change in presynaptic release. Furthermore, miniature NMDAR currents after PSD95 KD show an activity-triggered calcineurin sensitivity that is normally only found in the pre-EO period when SAP102 binds mixed GluN2A/GluN2B NMDARs. These data indicate that young SC LTP arises from PSD95 unsilencing of silent synapses, that unsilencing is labile in young brain, and that even though SAP102 and PSD95 can bind the same NMDARs, only PSD95 enables SC synaptic maturation.
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23
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Papouin T, Ladépêche L, Ruel J, Sacchi S, Labasque M, Hanini M, Groc L, Pollegioni L, Mothet JP, Oliet SHR. Synaptic and extrasynaptic NMDA receptors are gated by different endogenous coagonists. Cell 2012; 150:633-46. [PMID: 22863013 DOI: 10.1016/j.cell.2012.06.029] [Citation(s) in RCA: 507] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 04/18/2012] [Accepted: 06/05/2012] [Indexed: 11/20/2022]
Abstract
N-methyl-d-aspartate receptors (NMDARs) are located in neuronal cell membranes at synaptic and extrasynaptic locations, where they are believed to mediate distinct physiological and pathological processes. Activation of NMDARs requires glutamate and a coagonist whose nature and impact on NMDAR physiology remain elusive. We report that synaptic and extrasynaptic NMDARs are gated by different endogenous coagonists, d-serine and glycine, respectively. The regionalized availability of the coagonists matches the preferential affinity of synaptic NMDARs for d-serine and extrasynaptic NMDARs for glycine. Furthermore, glycine and d-serine inhibit NMDAR surface trafficking in a subunit-dependent manner, which is likely to influence NMDARs subcellular location. Taking advantage of this coagonist segregation, we demonstrate that long-term potentiation and NMDA-induced neurotoxicity rely on synaptic NMDARs only. Conversely, long-term depression requires both synaptic and extrasynaptic receptors. Our observations provide key insights into the operating mode of NMDARs, emphasizing functional distinctions between synaptic and extrasynaptic NMDARs in brain physiology.
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Affiliation(s)
- Thomas Papouin
- INSERM U862, Neurocentre Magendie, 33077 Bordeaux, France
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24
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Marsden W. Stressor-induced NMDAR dysfunction as a unifying hypothesis for the aetiology, pathogenesis and comorbidity of clinical depression. Med Hypotheses 2011; 77:508-28. [DOI: 10.1016/j.mehy.2011.06.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 06/05/2011] [Indexed: 02/07/2023]
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25
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Alamilla J, Gillespie DC. Glutamatergic inputs and glutamate-releasing immature inhibitory inputs activate a shared postsynaptic receptor population in lateral superior olive. Neuroscience 2011; 196:285-96. [PMID: 21907763 DOI: 10.1016/j.neuroscience.2011.08.060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 08/24/2011] [Accepted: 08/25/2011] [Indexed: 10/17/2022]
Abstract
Principal cells of the lateral superior olive (LSO) compute interaural intensity differences by comparing converging excitatory and inhibitory inputs. The excitatory input carries information from the ipsilateral ear, and the inhibitory input carries information from the contralateral ear. Throughout life, the excitatory input pathway releases glutamate. In adulthood, the inhibitory input pathway releases glycine. During a period of major developmental refinement in the LSO, however, synaptic terminals of the immature inhibitory input pathway release not only glycine, but also GABA and glutamate. To determine whether glutamate released by terminals in either pathway could spill over to activate postsynaptic N-methyl-d-aspartate (NMDA) receptors under the other pathway, we made whole-cell recordings from LSO principal cells in acute slices of neonatal rat brainstem bathed in the use-dependent NMDA receptor antagonist MK-801 and stimulated in the two opposing pathways. We found that during the first postnatal week glutamate spillover occurs bidirectionally from both immature excitatory terminals and immature inhibitory terminals. We further found that a population of postsynaptic NMDA receptors is shared: glutamate released from either pathway can diffuse to and activate these receptors. We suggest that these shared receptors contain the GluN2B subunit and are located extrasynaptically.
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Affiliation(s)
- J Alamilla
- Department of Psychology, Neuroscience and Behaviour, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
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26
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Fetterolf F, Foster KA. Regulation of long-term plasticity induction by the channel and C-terminal domains of GluN2 subunits. Mol Neurobiol 2011; 44:71-82. [PMID: 21604197 DOI: 10.1007/s12035-011-8190-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 05/09/2011] [Indexed: 12/30/2022]
Abstract
Conventional long-term potentiation (LTP) and long-term depression (LTD) are induced by different patterns of synaptic stimulation, but both forms of synaptic modification require calcium influx through NMDA receptors (NMDARs). A prevailing model (the "calcium hypothesis") suggests that high postsynaptic calcium elevation results in LTP, whereas moderate elevations give rise to LTD. Recently, additional evidence has come to suggest that differential activation of NMDAR subunits also factors in determining which type of plasticity is induced. While the growing amount of data suggest that activation of NMDARs containing specific GluN2 subunits plays an important role in the induction of plasticity, it remains less clear which subunit is tied to which form of plasticity. Additionally, it remains to be determined which properties of the subunits confer upon them the ability to differentially induce long-term plasticity. This review highlights recent studies suggesting differential roles for the subunits, as well as findings that begin to shed light on how two similar subunits may be linked to the induction of opposing forms of plasticity.
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Affiliation(s)
- Frank Fetterolf
- Department of Basic Science, The Commonwealth Medical College, 501 Madison Ave., Scranton, PA 18510, USA
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27
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Hillman BG, Gupta SC, Stairs DJ, Buonanno A, Dravid SM. Behavioral analysis of NR2C knockout mouse reveals deficit in acquisition of conditioned fear and working memory. Neurobiol Learn Mem 2011; 95:404-14. [PMID: 21295149 PMCID: PMC3432405 DOI: 10.1016/j.nlm.2011.01.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/30/2010] [Accepted: 01/21/2011] [Indexed: 12/21/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors play an important role in excitatory neurotransmission and mediate synaptic plasticity associated with learning and memory. NMDA receptors are composed of two NR1 and two NR2 subunits and the identity of the NR2 subunit confers unique electrophysiologic and pharmacologic properties to the receptor. The precise role of NR2C-containing receptors in vivo is poorly understood. We have performed a battery of behavioral tests on NR2C knockout/nβ-galactosidase knock-in mice and found no difference in spontaneous activity, basal anxiety, forced-swim immobility, novel object recognition, pain sensitivity and reference memory in comparison to wildtype counterparts. However, NR2C knockout mice were found to exhibit deficits in fear acquisition and working memory compared to wildtype mice. Deficit in fear acquisition correlated with lack of fear conditioning-induced plasticity at the thalamo-amygdala synapse. These findings suggest a unique role of NR2C-containing receptors in associative and executive learning representing a novel therapeutic target for deficits in cognition.
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Affiliation(s)
- Brandon G Hillman
- Department of Pharmacology, Creighton University, Omaha, NE 68178, USA
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28
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Proctor DT, Coulson EJ, Dodd PR. Post-synaptic scaffolding protein interactions with glutamate receptors in synaptic dysfunction and Alzheimer's disease. Prog Neurobiol 2011; 93:509-21. [PMID: 21382433 DOI: 10.1016/j.pneurobio.2011.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 02/18/2011] [Accepted: 02/24/2011] [Indexed: 11/19/2022]
Abstract
Alzheimer's disease (AD) is characterized clinically by an insidious decline in cognition. Much attention has been focused on proposed pathogenic mechanisms that relate Aβ plaque and neurofibrillary tangle pathology to cognitive symptoms, but compelling evidence now identifies early synaptic loss and dysfunction, which precede plaque and tangle formation, as the more probable initiators of cognitive impairment. Glutamate-mediated transmission is severely altered in AD. Glutamate receptor expression is most markedly altered in regions of the AD brain that show the greatest pathological changes. Signaling via glutamate receptors controls synaptic strength and plasticity, and changes in these parameters are likely to contribute to memory and cognitive deficits in AD. Glutamate receptor expression and activity are modulated by interactions with post-synaptic scaffolding proteins that augment the strength and direction of signal cascades initiated by glutamate receptor activity. Scaffold proteins offer promising targets for more focused and effective drug therapy. In consequence, interest is developing into the roles these proteins play in neurological disease. In this review we discuss disruptions to excitatory neurotransmission at the level of glutamate receptor-post-synaptic scaffolding protein interactions that may contribute to synaptic dysfunction in AD.
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Affiliation(s)
- Dustin T Proctor
- School of Chemistry and Molecular Biosciences, Molecular Biosciences Building #76, Coopers Road, St Lucia campus, University of Queensland, Brisbane 4072, Australia
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29
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NR2A subunit of the N-methyl d-aspartate receptors are required for potentiation at the mossy fiber to granule cell synapse and vestibulo-cerebellar motor learning. Neuroscience 2011; 176:274-83. [DOI: 10.1016/j.neuroscience.2010.12.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/15/2010] [Accepted: 12/15/2010] [Indexed: 01/28/2023]
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30
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Hardingham GE, Bading H. Synaptic versus extrasynaptic NMDA receptor signalling: implications for neurodegenerative disorders. Nat Rev Neurosci 2010; 11:682-96. [PMID: 20842175 PMCID: PMC2948541 DOI: 10.1038/nrn2911] [Citation(s) in RCA: 1115] [Impact Index Per Article: 79.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is a long-standing paradox that NMDA (N-methyl-D-aspartate) receptors (NMDARs) can both promote neuronal health and kill neurons. Recent studies show that NMDAR-induced responses depend on the receptor location: stimulation of synaptic NMDARs, acting primarily through nuclear Ca(2+) signalling, leads to the build-up of a neuroprotective 'shield', whereas stimulation of extrasynaptic NMDARs promotes cell death. These differences result from the activation of distinct genomic programmes and from opposing actions on intracellular signalling pathways. Perturbations in the balance between synaptic and extrasynaptic NMDAR activity contribute to neuronal dysfunction in acute ischaemia and Huntington's disease, and could be a common theme in the aetiology of neurodegenerative diseases. Neuroprotective therapies should aim to both enhance the effect of synaptic activity and disrupt extrasynaptic NMDAR-dependent death signalling.
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Affiliation(s)
- Giles E. Hardingham
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Im Neuenheimer Feld 364, D-69120 Heidelberg, Germany
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31
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Hippocampal long-term depression is required for the consolidation of spatial memory. Proc Natl Acad Sci U S A 2010; 107:16697-702. [PMID: 20823230 DOI: 10.1073/pnas.1008200107] [Citation(s) in RCA: 211] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and long-term depression (LTD) of glutamatergic transmission are candidate mechanisms for long-term spatial memory, the precise contributions of LTP and LTD remain poorly understood. Here, we report that LTP and LTD in the hippocampal CA1 region of freely moving adult rats were prevented by NMDAR 2A (GluN2A) and 2B subunit (GluN2B) preferential antagonists, respectively. These results strongly suggest that NMDAR subtype preferential antagonists are appropriate tools to probe the roles of LTP and LTD in spatial memory. Using a Morris water maze task, the LTP-blocking GluN2A antagonist had no significant effect on any aspect of performance, whereas the LTD-blocking GluN2B antagonist impaired spatial memory consolidation. Moreover, similar spatial memory deficits were induced by inhibiting the expression of LTD with intrahippocampal infusion of a short peptide that specifically interferes with AMPA receptor endocytosis. Taken together, our findings support a functional requirement of hippocampal CA1 LTD in the consolidation of long-term spatial memory.
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Specific involvement of postsynaptic GluN2B-containing NMDA receptors in the developmental elimination of corticospinal synapses. Proc Natl Acad Sci U S A 2010; 107:15252-7. [PMID: 20696923 DOI: 10.1073/pnas.0906551107] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The GluN2B (GluRepsilon2/NR2B) and GluN2A (GluRepsilon1/NR2A) NMDA receptor (NMDAR) subtypes have been differentially implicated in activity-dependent synaptic plasticity. However, little is known about the respective contributions made by these two subtypes to developmental plasticity, in part because studies of GluN2B KO [Grin2b(-/-) (2b(-/-))] mice are hampered by early neonatal mortality. We previously used in vitro slice cocultures of rodent cerebral cortex (Cx) and spinal cord (SpC) to show that corticospinal (CS) synapses, once present throughout the SpC, are eliminated from the ventral side during development in an NMDAR-dependent manner. To study subtype specificity of NMDAR in this developmental plasticity, we cocultured Cx and SpC slices derived from postnatal day 0 (P0) animals with different genotypes [2b(-/-), Grin2a(-/-) (2a(-/-)), or WT mice]. The distribution of CS synapses was studied electrophysiologically and with a voltage-sensitive dye. Synapse elimination on the ventral side was blocked in WT(Cx)-2b(-/-)(SpC) pairs but not in WT(Cx)-2a(-/-)(SpC) or 2b(-/-)(Cx)-WT(SpC) pairs. CS axonal regression was also observed through live imaging of CS axons labeled with enhanced yellow fluorescent protein (EYFP) through exo utero electroporation. These findings suggest that postsynaptic GluN2B is selectively involved in CS synapse elimination. In addition, the elimination was not blocked in 2a(-/-) SpC slices, where Ca(2+) entry through GluN2B-mediated CS synaptic currents was reduced to the same level as in 2b(-/-) slices, suggesting that the differential effect of GluN2B and GluN2A in CS synapse elimination might not be explained based solely on greater Ca(2+) entry through GluN2B-containing channels.
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Setdb1 histone methyltransferase regulates mood-related behaviors and expression of the NMDA receptor subunit NR2B. J Neurosci 2010; 30:7152-67. [PMID: 20505083 DOI: 10.1523/jneurosci.1314-10.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Histone methyltransferases specific for the histone H3-lysine 9 residue, including Setdb1 (Set domain, bifurcated 1)/Eset/Kmt1e are associated with repressive chromatin remodeling and expressed in adult brain, but potential effects on neuronal function and behavior remain unexplored. Here, we report that transgenic mice with increased Setdb1 expression in adult forebrain neurons show antidepressant-like phenotypes in behavioral paradigms for anhedonia, despair, and learned helplessness. Chromatin immunoprecipitation in conjunction with DNA tiling arrays (ChIP-chip) revealed that genomic occupancies of neuronal Setdb1 are limited to <1% of annotated genes, which include the NMDA receptor subunit NR2B/Grin2B and other ionotropic glutamate receptor genes. Chromatin conformation capture and Setdb1-ChIP revealed a loop formation tethering the NR2B/Grin2b promoter to the Setdb1 target site positioned 30 kb downstream of the transcription start site. In hippocampus and ventral striatum, two key structures in the neuronal circuitry regulating mood-related behaviors, Setdb1-mediated repressive histone methylation at NR2B/Grin2b was associated with decreased NR2B expression and EPSP insensitivity to pharmacological blockade of NR2B, and accelerated NMDA receptor desensitization consistent with a shift in NR2A/B subunit ratios. In wild-type mice, systemic treatment with the NR2B antagonist, Ro25-6981 [R-(R,S)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidine propranol], and hippocampal small interfering RNA-mediated NR2B/Grin2b knockdown resulted in behavioral changes similar to those elicited by the Setdb1 transgene. Together, these findings point to a role for neuronal Setdb1 in the regulation of affective and motivational behaviors through repressive chromatin remodeling at a select set of target genes, resulting in altered NMDA receptor subunit composition and other molecular adaptations.
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Kristiansen LV, Bakir B, Haroutunian V, Meador-Woodruff JH. Expression of the NR2B-NMDA receptor trafficking complex in prefrontal cortex from a group of elderly patients with schizophrenia. Schizophr Res 2010; 119:198-209. [PMID: 20347576 PMCID: PMC2868940 DOI: 10.1016/j.schres.2010.02.1069] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 02/23/2010] [Accepted: 02/25/2010] [Indexed: 10/19/2022]
Abstract
Dysregulated glutamate neurotransmission has been implicated in the pathophysiology of schizophrenia. In particular, hypofunction of the NMDA glutamate receptor has been proposed to play an important role in mediating cognitive deficits in patients. The two NMDA receptor subunits, NR2A and NR2B, are distinctly regulated during development and are associated with different intracellular pathways and functions, which suggest that these receptors play separate roles in the control of higher cognitive functions such as learning and memory. Trafficking of the NR2B subunit-containing receptor is regulated by a microtubule-associated trafficking complex consisting of the KIF17, APBA1, CASK, and mLin7 proteins. Several studies have demonstrated an integrated functional regulation of this trafficking complex with NR2B receptor subunit expression, which in turn has been linked to higher cognitive functions. In the present work, we investigated whether expression of this NR2B-associated trafficking complex might be abnormal in schizophrenia. We analyzed the expression of KIF17, APBA1, CASK, mLin7A and mLin7C in postmortem brain from patients with schizophrenia a comparison group. Analysis of transcripts for all of these proteins revealed particularly prominent expression in cortical layer III and layer IV, which overlapped with NR2B but not NR2A transcripts. We found altered expression of transcripts for the CASK, ABPA1, and mLin7 molecules and the CASK, mLin7 proteins, suggesting that NR2B-containing NMDA receptor transport could be selectively compromised in schizophrenia, and that these changes likely involve altered NR2B function in a subset of cortical neurons.
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Affiliation(s)
- LV Kristiansen
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
,Corresponding author: European Science Foundation, 1 Quai Lezai-Marnésia 67080 Strasbourg Cedex, France, Telephone, +33 658631018, Fax: +33 388 370532,
| | - B Bakir
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - V Haroutunian
- Department of Psychiatry, Mount Sinai School of Medicine, Bronx VA Medical Center, Bronx, NY 10468, USA.
| | - JH Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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Xue L, Zhang F, Chen X, Lin J, Shi J. PDZ protein mediated activity-dependent LTP/LTD developmental switch at rat retinocollicular synapses. Am J Physiol Cell Physiol 2010; 298:C1572-82. [PMID: 20457829 DOI: 10.1152/ajpcell.00012.2010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The insertion of amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors into the plasma membrane and removal via internalization are essential for regulating synaptic strength, which underlies the basic mechanism of learning and memory. The retinocollicular pathway undergoes synaptic refinement during development and shows a wide variety of long-term synaptic changes; however, still little is known about its underlying molecular regulation. Here we report a rapid developmental long-term potentiation (LTP)/long-term depression (LTD) switch and its intracellular mechanism at the rat retinocollicular pathway from postnatal day 5 (P5) to P14. Before P9, neurons always exhibited LTP, whereas LTD was observed only after P10. Blockade of GluR2/3-glutamate receptor-interacting protein (GRIP)/AMPA-receptor-binding protein (ABP)/protein interacting with C kinase 1 (PICK1) interactions with pep2-SVKI could sustain the LTP after P10. This suggests that the LTP/LTD switch relied on PDZ protein activities. Selective interruption of GluR2/3-PICK1 binding by pep2-EVKI blocked the long-lasting effects of both LTP and LTD, suggesting a role for PICK1 in the maintenance of long-term synaptic plasticity. Interestingly, synaptic expression of GRIP increased more than twofold from P7 to P11, whereas ABP and PICK1 expression levels remained stable. Blockade of spontaneous retinal input suppressed this increase and abolished the LTP/LTD switch. These results suggest that the increased GRIP synaptic expression may be a key regulatory factor in mediating the activity-dependent developmental LTP/LTD switch, whereas PICK1 may be required for both LTP and LTD to maintain their long-term effects.
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Affiliation(s)
- Lei Xue
- NINDS, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA.
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Neuroplastic alterations in the limbic system following cocaine or alcohol exposure. Curr Top Behav Neurosci 2010; 3:3-27. [PMID: 21161748 DOI: 10.1007/7854_2009_23] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Neuroplastic changes in the CNS are thought to be a fundamental component of learning and memory. While pioneering studies in the hippocampus and cerebellum have detailed many of the basic mechanisms that can lead to alterations in synaptic transmission based on previous activity, only more recently has synaptic plasticity been monitored after behavioral manipulation or drug exposure. In this chapter, we review evidence that drugs of abuse are powerful modulators of synaptic plasticity. Both the dopaminergic neurons of the ventral tegmental area as well medium spiny neurons in nucleus accumbens show enhanced excitatory synaptic strength following passive or active exposure to drugs such as cocaine and alcohol. In the VTA, both the enhancement of excitatory synaptic strength and the acquisition of drug-related behaviors depend on signaling through the N-methyl-D: -aspartate receptors (NMDARs) which are mechanistically thought to lead to increased synaptic insertion of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). Synaptic insertion of AMPARs by drugs of abuse can be long lasting, depending on the route of administration, number of drug exposures, or whether the drugs are received passively or self-administered.
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Deng Y, Xu Z, Xu B, Tian Y, Deng X, Xin X, Gao J. Excitotoxicity in rat's brain induced by exposure of manganese and neuroprotective effects of pinacidil and nimodipine. Biol Trace Elem Res 2009; 131:143-53. [PMID: 19300915 DOI: 10.1007/s12011-009-8361-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
Abstract
Manganese (Mn) is an essential trace element for humans. However, manganism would be caused by excessive Mn. The mechanisms underlying excitotoxicity induced by manganism are poorly understood. As it is known to us, glutamate (Glu) is the most prevalent excitatory neurotransmitter. To determine the possible role of dysfunction of Glu transportation and metabolism in Mn-induced excitotoxicity, the rats were ip injected with different dose of MnCl(2) (0, 50, 100, and 200 micromol/kg), the levels of Mn and activities of GS, PAG, Na(+)-K(+)-ATPase, and Ca(2+)-ATPase in striatum were investigated. In addition, effect of 20.38 micromol/kg pinacidil (K(+) channel opener) or 2.4 micromol/kg nimodipine (Ca(2+) channel blocker) were studied at 200 micromol/kg MnCl(2). With dose-dependent inhibition of GS, Na(+)-K(+)-ATPase, and Ca(2+)-ATPase activities, increase of Mn levels and PAG activity were observed. Further investigation indicated that pre-treatment of pinacidil or nimodipine reversed toxic effect of MnCl(2) significantly. These results suggested that MnCl(2) could induce dysfunction of Glu transportation and metabolism by augmenting the excitotoxicity dose-dependently; pinacidil and nimodipine might antagonize manganese neurotoxicity.
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Affiliation(s)
- Yu Deng
- Department of environmental health, School of Public Health, China Medical University, Shenyang, People's Republic of China
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Glutamatergic neurotransmission in the nucleus tractus solitarii: structural and functional characteristics. J Chem Neuroanat 2009; 38:145-53. [PMID: 19778680 DOI: 10.1016/j.jchemneu.2009.03.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 03/16/2009] [Accepted: 03/17/2009] [Indexed: 12/29/2022]
Abstract
Glutamate is the main excitatory transmitter in the central nervous system. As such, it plays a major role in transmitting and processing visceral sensory information within the nucleus tractus solitarii (NTS). Here, we review current knowledge on NTS glutamatergic transmission. We describe the main organizational features of NTS glutamatergic synapses as determined by work performed during the last decade using antibodies against glutamate receptors and transporters proteins. In light of these recent neuronatomical findings, we discuss some functional properties of developing and adult NTS glutamatergic synapses.
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Schober ME, McKnight RA, Yu X, Callaway CW, Ke X, Lane RH. Intrauterine growth restriction due to uteroplacental insufficiency decreased white matter and altered NMDAR subunit composition in juvenile rat hippocampi. Am J Physiol Regul Integr Comp Physiol 2009; 296:R681-92. [DOI: 10.1152/ajpregu.90396.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Uteroplacental insufficiency (UPI), the major cause of intrauterine growth restriction (IUGR) in developed nations, predisposes to learning impairment. The underlying mechanism is unknown. Neuronal N-methyl-d-aspartate receptors (NMDARs) are critical for synaptogenesis and learning throughout life. We hypothesized that UPI-induced IUGR alters rat hippocampal NMDAR NR2A/NR2B subunit ratio and/or NR1 mRNA isoform expression and synaptic density at day 21 (P21). To test this hypothesis, IUGR was induced by bilateral uterine artery ligation of the late-gestation Sprague-Dawley dam. At P21, hippocampal NMDAR subunit mRNA and protein were measured, as were levels of synaptophysin. Neuronal, synaptic, and glial density in CA1, CA3, and dentate gyrus (DG) was assessed by immunofluorescence. IUGR increased NR1 mRNA isoform NR1-3a and 1-3b expression in both sexes. In P21 males, IUGR increased protein levels of NR1 C2′ and decreased NR1 C2, NR2A, and the NR2A-to-NR2B ratio, whereas in females, IUGR increased NR2B protein. In males, IUGR was associated with decreased myelin basic protein-to-neuronal nuclei ratio in CA1, CA3, and DG. We conclude that IUGR has sex-specific effects and that neither neuronal loss nor decreased synaptic density appears to account for the changes in NMDAR subunits. Rather, it is possible that synaptic NMDAR subunit composition is altered. Our results suggest that apparent recovery in the IUGR hippocampus may be associated with synaptic hyperexcitability. We speculate that the NMDAR plays an important role in IUGR-associated cognitive impairment.
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Yashiro K, Philpot BD. Regulation of NMDA receptor subunit expression and its implications for LTD, LTP, and metaplasticity. Neuropharmacology 2008; 55:1081-94. [PMID: 18755202 DOI: 10.1016/j.neuropharm.2008.07.046] [Citation(s) in RCA: 479] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 01/26/2023]
Abstract
NMDA-type glutamate receptors (NMDARs) mediate many forms of synaptic plasticity. These tetrameric receptors consist of two obligatory NR1 subunits and two regulatory subunits, usually a combination of NR2A and NR2B. In the neonatal neocortex NR2B-containing NMDARs predominate, and sensory experience facilitates a developmental switch in which NR2A levels increase relative to NR2B. In this review, we clarify the roles of NR2 subunits in synaptic plasticity, and argue that a primary role of this shift is to control the threshold, rather than determining the direction, for modifying synaptic strength. We also discuss recent studies that illuminate the mechanisms regulating NR2 subunits, and suggest that the NR2A/NR2B ratio is regulated by multiple means, which may control the ratio both locally at individual synapses and globally in a cell-wide manner. Finally, we use the visual cortex as a model system to illustrate how activity-dependent modifications in the NR2A/NR2B ratio may contribute to the development of cortical functions.
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Affiliation(s)
- Koji Yashiro
- Department of Cell and Molecular Physiology, Neuroscience Center, and Neurobiology Curriculum, University of North Carolina, Neuroscience Research Building, Campus Box 7545, 115 Mason Farm Road, Chapel Hill, NC 27599-7545, USA.
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