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Sheynikhovich D, Otani S, Bai J, Arleo A. Long-term memory, synaptic plasticity and dopamine in rodent medial prefrontal cortex: Role in executive functions. Front Behav Neurosci 2023; 16:1068271. [PMID: 36710953 PMCID: PMC9875091 DOI: 10.3389/fnbeh.2022.1068271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 12/26/2022] [Indexed: 01/12/2023] Open
Abstract
Mnemonic functions, supporting rodent behavior in complex tasks, include both long-term and (short-term) working memory components. While working memory is thought to rely on persistent activity states in an active neural network, long-term memory and synaptic plasticity contribute to the formation of the underlying synaptic structure, determining the range of possible states. Whereas, the implication of working memory in executive functions, mediated by the prefrontal cortex (PFC) in primates and rodents, has been extensively studied, the contribution of long-term memory component to these tasks received little attention. This review summarizes available experimental data and theoretical work concerning cellular mechanisms of synaptic plasticity in the medial region of rodent PFC and the link between plasticity, memory and behavior in PFC-dependent tasks. A special attention is devoted to unique properties of dopaminergic modulation of prefrontal synaptic plasticity and its contribution to executive functions.
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Affiliation(s)
- Denis Sheynikhovich
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France,*Correspondence: Denis Sheynikhovich ✉
| | - Satoru Otani
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Jing Bai
- Institute of Psychiatry and Neuroscience of Paris, INSERM U1266, Paris, France
| | - Angelo Arleo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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Romero-Barragán MT, Gruart A, Delgado-García JM. Transsynaptic Long-Term Potentiation in the Hippocampus of Behaving Mice. Front Synaptic Neurosci 2022; 13:811806. [PMID: 35126083 PMCID: PMC8810508 DOI: 10.3389/fnsyn.2021.811806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/31/2021] [Indexed: 11/17/2022] Open
Abstract
Long-term potentiation (LTP) is an experimental procedure that shares certain mechanisms with neuronal learning and memory processes and represents a well-known example of synaptic plasticity. LTP consists of an increase of the synaptic response to a control stimulus following the presentation of a high-frequency stimulation (HFS) train to an afferent pathway. This technique is studied mostly in the hippocampus due to the latter’s high susceptibility and its laminar nature which facilitates the location of defined synapses. Although most preceding studies have been performed in vitro, we have developed an experimental approach to carry out these experiments in alert behaving animals. The main goal of this study was to confirm the existence of synaptic changes in strength in synapses that are post-synaptic to the one presented with the HFS. We recorded field excitatory post-synaptic potentials (fEPSPs) evoked in five hippocampal synapses, from both hemispheres, of adult male mice. HFS was presented to the perforant pathway (PP). We characterized input/output curves, paired-pulse stimulation, and LTP of these synapses. We also performed depth-profile recordings to determine differences in fEPSP latencies. Collected data indicate that the five selected synapses have similar basic electrophysiological properties, a fact that enables an easier comparison of LTP characteristics. Importantly, we observed the presence of significant LTP in the contralateral CA1 (cCA1) area following the control stimulation of non-HFS-activated pathways. These results indicate that LTP appears as a physiological process present in synapses located far away from the HFS-stimulated afferent pathway.
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Lleó A, Núñez-Llaves R, Alcolea D, Chiva C, Balateu-Paños D, Colom-Cadena M, Gomez-Giro G, Muñoz L, Querol-Vilaseca M, Pegueroles J, Rami L, Lladó A, Molinuevo JL, Tainta M, Clarimón J, Spires-Jones T, Blesa R, Fortea J, Martínez-Lage P, Sánchez-Valle R, Sabidó E, Bayés À, Belbin O. Changes in Synaptic Proteins Precede Neurodegeneration Markers in Preclinical Alzheimer's Disease Cerebrospinal Fluid. Mol Cell Proteomics 2019; 18:546-560. [PMID: 30606734 PMCID: PMC6398205 DOI: 10.1074/mcp.ra118.001290] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Indexed: 01/08/2023] Open
Abstract
A biomarker of synapse loss, an early event in Alzheimer's disease (AD) pathophysiology that precedes neuronal death and symptom onset, would be a much-needed prognostic biomarker. With direct access to the brain interstitial fluid, the cerebrospinal fluid (CSF) is a potential source of synapse-derived proteins. In this study, we aimed to identify and validate novel CSF biomarkers of synapse loss in AD. Discovery: Combining shotgun proteomics of the CSF with an exhaustive search of the literature and public databases, we identified 251 synaptic proteins, from which we selected 22 for further study. Verification: Twelve proteins were discarded because of poor detection by Selected Reaction Monitoring (SRM). We confirmed the specific expression of 9 of the remaining proteins (Calsynytenin-1, GluR2, GluR4, Neurexin-2A, Neurexin-3A, Neuroligin-2, Syntaxin-1B, Thy-1, Vamp-2) at the human synapse using Array Tomography microscopy and biochemical fractionation methods. Exploration: Using SRM, we monitored these 9 synaptic proteins (20 peptides) in a cohort of CSF from cognitively normal controls and subjects in the pre-clinical and clinical AD stages (n = 80). Compared with controls, peptides from 8 proteins were elevated 1.3 to 1.6-fold (p < 0.04) in prodromal AD patients. Validation: Elevated levels of a GluR4 peptide at the prodromal stage were replicated (1.3-fold, p = 0.04) in an independent cohort (n = 60). Moreover, 7 proteins were reduced at preclinical stage 1 (0.6 to 0.8-fold, p < 0.04), a finding that was replicated (0.7 to 0.8-fold, p < 0.05) for 6 proteins in a third cohort (n = 38). In a cross-cohort meta-analysis, 6 synaptic proteins (Calsyntenin-1, GluR4, Neurexin-2A, Neurexin-3A, Syntaxin-1B and Thy-1) were reduced 0.8-fold (p < 0.05) in preclinical AD, changes that precede clinical symptoms and CSF markers of neurodegeneration. Therefore, these proteins could have clinical value for assessing disease progression, especially in preclinical stages of AD.
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Affiliation(s)
- Alberto Lleó
- From the ‡Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain;
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Raúl Núñez-Llaves
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Daniel Alcolea
- From the ‡Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Cristina Chiva
- ‖Proteomics Unit, Center for Genomics Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona
- **University Pompeu Fabra, 08003 Barcelona
| | | | - Martí Colom-Cadena
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Gemma Gomez-Giro
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Laia Muñoz
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Marta Querol-Vilaseca
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Jordi Pegueroles
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Lorena Rami
- ‡‡Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic-Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), 08015 Barcelona, Spain
| | - Albert Lladó
- ‡‡Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic-Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), 08015 Barcelona, Spain
| | - José L Molinuevo
- ‡‡Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic-Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), 08015 Barcelona, Spain
| | - Mikel Tainta
- §§Department of Neurology, Center for Research and Advanced Therapies, CITA-Alzheimer Foundation, 20009 San Sebastian, Spain
- ¶¶Servicio de Neurologia, Organización Sanitaria Integrada Goierri-Alto Urola, Osakidetza, Zumárraga, España
| | - Jordi Clarimón
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
| | - Tara Spires-Jones
- ‖‖Centre for Discovery Brain Sciences and UK Dementia Research Institute, University of Edinburgh EH8 9JZ, UK
| | - Rafael Blesa
- From the ‡Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Juan Fortea
- From the ‡Memory Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Pablo Martínez-Lage
- §§Department of Neurology, Center for Research and Advanced Therapies, CITA-Alzheimer Foundation, 20009 San Sebastian, Spain
| | - Raquel Sánchez-Valle
- ‡‡Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic-Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), 08015 Barcelona, Spain
| | - Eduard Sabidó
- ‖Proteomics Unit, Center for Genomics Regulation, Barcelona Institute of Science and Technology, 08003 Barcelona
- **University Pompeu Fabra, 08003 Barcelona
| | - Àlex Bayés
- ***Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025, Barcelona, Spain
- ‡‡‡Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain
| | - Olivia Belbin
- §Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain;
- ¶Biomedical Research Institute Sant Pau (IIB Sant Pau), 08025Barcelona, Spain
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Ramos-Miguel A, Sawada K, Jones AA, Thornton AE, Barr AM, Leurgans SE, Schneider JA, Bennett DA, Honer WG. Presynaptic proteins complexin-I and complexin-II differentially influence cognitive function in early and late stages of Alzheimer's disease. Acta Neuropathol 2017; 133:395-407. [PMID: 27866231 PMCID: PMC6542594 DOI: 10.1007/s00401-016-1647-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 11/12/2016] [Accepted: 11/13/2016] [Indexed: 12/14/2022]
Abstract
Progressive accumulation of Alzheimer's disease-related pathology is associated with cognitive dysfunction. Differences in cognitive reserve may contribute to individual differences in cognitive function in the presence of comparable neuropathology. The protective effects of cognitive reserve could contribute differentially in early versus late stages of the disease. We investigated presynaptic proteins as measures of brain reserve (a subset of total cognitive reserve), and used Braak staging to estimate the progression of Alzheimer's disease. Antemortem evaluations of cognitive function, postmortem assessments of pathologic indices, and presynaptic protein analyses, including the complexins I and II as respective measures of inhibitory and excitatory terminal function, were assayed in multiple key brain regions in 418 deceased participants from a community study. After covarying for demographic variables, pathologic indices, and overall synapse density, lower brain complexin-I and -II levels contributed to cognitive dysfunction (P < 0.01). Each complexin appeared to be dysregulated at a different Braak stage. Inhibitory complexin-I explained 14.4% of the variance in global cognition in Braak 0-II, while excitatory complexin-II explained 7.3% of the variance in Braak V-VI. Unlike other presynaptic proteins, complexins did not colocalize with pathologic tau within neuritic plaques, suggesting that these functional components of the synaptic machinery are cleared early from dystrophic neurites. Moreover, complexin levels showed distinct patterns of change related to memory challenges in a rat model, supporting the functional specificity of these proteins. The present results suggest that disruption of inhibitory synaptic terminals may trigger early cognitive impairment, while excitatory terminal disruption may contribute relatively more to later cognitive impairment.
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Affiliation(s)
- Alfredo Ramos-Miguel
- BC Mental Health and Addictions Research Institute, 938 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 2A1, Canada
| | - Ken Sawada
- Kochi Prefectural Aki General Hospital, 3-33 Hoheicho, Kochi, 784-0027, Japan
| | - Andrea A Jones
- BC Mental Health and Addictions Research Institute, 938 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 2A1, Canada
| | - Allen E Thornton
- BC Mental Health and Addictions Research Institute, 938 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada
| | - Alasdair M Barr
- BC Mental Health and Addictions Research Institute, 938 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Sue E Leurgans
- Rush Alzheimer's Disease Center, Rush University Medical Center, 600 S Paulina Street, Chicago, IL, 60612, USA
| | - Julie A Schneider
- Rush Alzheimer's Disease Center, Rush University Medical Center, 600 S Paulina Street, Chicago, IL, 60612, USA
| | - David A Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, 600 S Paulina Street, Chicago, IL, 60612, USA
| | - William G Honer
- BC Mental Health and Addictions Research Institute, 938 West 28th Avenue, Vancouver, BC, V5Z 4H4, Canada.
- Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 2A1, Canada.
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Borovok N, Nesher E, Levin Y, Reichenstein M, Pinhasov A, Michaelevski I. Dynamics of Hippocampal Protein Expression During Long-term Spatial Memory Formation. Mol Cell Proteomics 2015; 15:523-41. [PMID: 26598641 DOI: 10.1074/mcp.m115.051318] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Indexed: 01/08/2023] Open
Abstract
Spatial memory depends on the hippocampus, which is particularly vulnerable to aging. This vulnerability has implications for the impairment of navigation capacities in older people, who may show a marked drop in performance of spatial tasks with advancing age. Contemporary understanding of long-term memory formation relies on molecular mechanisms underlying long-term synaptic plasticity. With memory acquisition, activity-dependent changes occurring in synapses initiate multiple signal transduction pathways enhancing protein turnover. This enhancement facilitates de novo synthesis of plasticity related proteins, crucial factors for establishing persistent long-term synaptic plasticity and forming memory engrams. Extensive studies have been performed to elucidate molecular mechanisms of memory traces formation; however, the identity of plasticity related proteins is still evasive. In this study, we investigated protein turnover in mouse hippocampus during long-term spatial memory formation using the reference memory version of radial arm maze (RAM) paradigm. We identified 1592 proteins, which exhibited a complex picture of expression changes during spatial memory formation. Variable linear decomposition reduced significantly data dimensionality and enriched three principal factors responsible for variance of memory-related protein levels at (1) the initial phase of memory acquisition (165 proteins), (2) during the steep learning improvement (148 proteins), and (3) the final phase of the learning curve (123 proteins). Gene ontology and signaling pathways analysis revealed a clear correlation between memory improvement and learning phase-curbed expression profiles of proteins belonging to specific functional categories. We found differential enrichment of (1) neurotrophic factors signaling pathways, proteins regulating synaptic transmission, and actin microfilament during the first day of the learning curve; (2) transcription and translation machinery, protein trafficking, enhancement of metabolic activity, and Wnt signaling pathway during the steep phase of memory formation; and (3) cytoskeleton organization proteins. Taken together, this study clearly demonstrates dynamic assembly and disassembly of protein-protein interaction networks depending on the stage of memory formation engrams.
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Affiliation(s)
- Natalia Borovok
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Elimelech Nesher
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Yishai Levin
- ¶de Botton Institute for Protein Profiling, The Nancy & Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Michal Reichenstein
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel
| | - Albert Pinhasov
- §Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
| | - Izhak Michaelevski
- From the ‡Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel-Aviv 6997801, Israel; ‖Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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Bañuelos C, Beas BS, McQuail JA, Gilbert RJ, Frazier CJ, Setlow B, Bizon JL. Prefrontal cortical GABAergic dysfunction contributes to age-related working memory impairment. J Neurosci 2014; 34:3457-66. [PMID: 24599447 PMCID: PMC3942567 DOI: 10.1523/jneurosci.5192-13.2014] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/15/2014] [Accepted: 01/20/2014] [Indexed: 12/12/2022] Open
Abstract
Working memory functions supported by the prefrontal cortex decline in normal aging. Disruption of corticolimbic GABAergic inhibitory circuits can impair working memory in young subjects; however, relatively little is known regarding how aging impacts prefrontal cortical GABAergic signaling and whether such changes contribute to cognitive deficits. The current study used a rat model to evaluate the effects of aging on expression of prefrontal GABAergic synaptic proteins in relation to working memory decline, and to test whether pharmacological manipulations of prefrontal GABAergic signaling can improve working memory abilities in aged subjects. Results indicate that in aged medial prefrontal cortex (mPFC), expression of the vesicular GABA transporter VGAT was unchanged; however, there was a significant increase in expression of the GABA synthesizing enzyme GAD67, and a significant decrease in the primary neuronal GABA transporter GAT-1 and in both subunits of the GABA(B) receptor (GABA(B)R). Expression of VGAT, GAD67, and GAT-1 was not associated with working memory ability. In contrast, among aged rats, GABA(B)R expression was significantly and negatively associated with working memory performance, such that lower GABA(B)R expression predicted better working memory. Subsequent experiments showed that systemic administration of a GABA(B)R antagonist, CGP55845, dose-dependently enhanced working memory in aged rats. This enhancing effect of systemic CGP55845 was reproduced by direct intra-mPFC administration. Together, these data suggest that age-related dysregulation of GABAergic signaling in prefrontal cortex may play a causal role in impaired working memory and that targeting GABA(B)Rs may provide therapeutic benefit for age-related impairments in executive functions.
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Affiliation(s)
| | | | | | | | - Charles J. Frazier
- Department of Neuroscience
- Department of Pharmacodynamics, University of Florida, Gainesville, Florida 32610
| | - Barry Setlow
- Department of Neuroscience
- Department of Psychiatry
| | - Jennifer L. Bizon
- Department of Neuroscience
- Department of Psychiatry
- McKnight Brain Institute, and
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Fernández-Ruiz A, Makarov VA, Herreras O. Sustained increase of spontaneous input and spike transfer in the CA3-CA1 pathway following long-term potentiation in vivo. Front Neural Circuits 2012; 6:71. [PMID: 23060752 PMCID: PMC3464490 DOI: 10.3389/fncir.2012.00071] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 09/18/2012] [Indexed: 01/23/2023] Open
Abstract
Long-term potentiation (LTP) is commonly used to study synaptic plasticity but the associated changes in the spontaneous activity of individual neurons or the computational properties of neural networks in vivo remain largely unclear. The multisynaptic origin of spontaneous spikes makes it difficult to estimate the impact of a particular potentiated input. Accordingly, we adopted an approach that isolates pathway-specific postsynaptic activity from raw local field potentials (LFPs) in the rat hippocampus in order to study the effects of LTP on ongoing spike transfer between cell pairs in the CA3-CA1 pathway. CA1 Schaffer-specific LFPs elicited by spontaneous clustered firing of CA3 pyramidal cells involved a regular succession of elementary micro-field-EPSPs (gamma-frequency) that fired spikes in CA1 units. LTP increased the amplitude but not the frequency of these ongoing excitatory quanta. Also, the proportion of Schaffer-driven spikes in both CA1 pyramidal cells and interneurons increased in a cell-specific manner only in previously connected CA3-CA1 cell pairs, i.e., when the CA3 pyramidal cell had shown pre-LTP significant correlation with firing of a CA1 unit and potentiated spike-triggered average (STA) of Schaffer LFPs following LTP. Moreover, LTP produced subtle reorganization of presynaptic CA3 cell assemblies. These findings show effective enhancement of pathway-specific ongoing activity which leads to increased spike transfer in potentiated segments of a network. They indicate that plastic phenomena induced by external protocols may intensify spontaneous information flow across specific channels as proposed in transsynaptic propagation of plasticity and synfire chain hypotheses that may be the substrate for different types of memory involving multiple brain structures.
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Affiliation(s)
- Antonio Fernández-Ruiz
- Department of Systems Neuroscience, Cajal Institute-Consejo Superior de Investigaciones Científicas Madrid, Spain
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Cholinergic and glutamatergic alterations beginning at the early stages of Alzheimer disease: participation of the phospholipase A2 enzyme. Psychopharmacology (Berl) 2008; 198:1-27. [PMID: 18392810 DOI: 10.1007/s00213-008-1092-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 01/28/2008] [Indexed: 12/14/2022]
Abstract
RATIONALE Alzheimer disease (AD), a progressive neurodegenerative disorder, is the leading cause of dementia in the elderly. A combination of cholinergic and glutamatergic dysfunction appears to underlie the symptomatology of AD, and thus, treatment strategies should address impairments in both systems. Evidence suggests the involvement of phospholipase A(2) (PLA(2)) enzyme in memory impairment and neurodegeneration in AD via actions on both cholinergic and glutamatergic systems. OBJECTIVES To review cholinergic and glutamatergic alterations underlying cognitive impairment and neuropathology in AD and attempt to link PLA(2) with such alterations. METHODS Medline databases were searched (no date restrictions) for published articles with links among the terms Alzheimer disease (mild, moderate, severe), mild cognitive impairment, choline acetyltransferase, acetylcholinesterase, NGF, NGF receptor, muscarinic receptor, nicotinic receptor, NMDA, AMPA, metabotropic glutamate receptor, atrophy, glucose metabolism, phospholipid metabolism, sphingolipid, membrane fluidity, phospholipase A(2), arachidonic acid, attention, memory, long-term potentiation, beta-amyloid, tau, inflammation, and reactive species. Reference lists of the identified articles were checked to identify additional studies of interest. RESULTS Overall, results suggest the hypothesis that persistent inhibition of cPLA(2) and iPLA(2) isoforms at early stages of AD may play a central role in memory deficits and beta-amyloid production through down-regulation of cholinergic and glutamate receptors. As the disease progresses, beta-amyloid induced up-regulation of cPLA(2) and sPLA(2) isoforms may play critical roles in inflammation and oxidative stress, thus participating in the neurodegenerative process. CONCLUSION Activation and inhibition of specific PLA(2) isoforms at different stages of AD could be of therapeutic importance and delay cognitive dysfunction and neurodegeneration.
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Bozon B, Kelly A, Josselyn SA, Silva AJ, Davis S, Laroche S. MAPK, CREB and zif268 are all required for the consolidation of recognition memory. Philos Trans R Soc Lond B Biol Sci 2003; 358:805-14. [PMID: 12740127 PMCID: PMC1693143 DOI: 10.1098/rstb.2002.1224] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
There has been nearly a century of interest in the idea that encoding and storage of information in the brain requires changes in the efficacy of synaptic connections between neurons that are activated during learning. Recent research into the molecular mechanisms of long-term potentiation (LTP) has brought about new knowledge that has provided valuable insights into the neural mechanisms of memory storage. The evidence indicates that rapid activation of the genetic machinery can be a key mechanism underlying the enduring modification of neural networks required for the stability of memories. In recent years, a wealth of experimental data has highlighted the importance of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signalling in the regulation of gene transcription in neurons. Here, we briefly review experiments that have shown MAPK/ERK, cAMP response element-binding protein (CREB) and the immediate early gene (IEG) zif268 are essential components of a signalling cascade required for the expression of late phase LTP and of certain forms of long-term memory. We also present experiments in which we have assessed the role of these three molecules in recognition memory. We show that pharmacological blockade of MAPK/ERK phosphorylation, functional inactivation of CREB in an inducible transgenic mouse and inactivation of zif268 in a mutant mouse result in a similar deficit in long-term recognition memory. In the continuing debate about the role of LTP mechanisms in memory, these findings provide an important complement to the suggestion that synaptic changes brought about by LTP and memory consolidation and storage share, at least in part, common underlying molecular mechanisms.
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Affiliation(s)
- Bruno Bozon
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, CNRS UMR 8620, Université Paris-Sud, 91405 Orsay, France
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Redistribution of syntaxin mRNA in neuronal cell bodies regulates protein expression and transport during synapse formation and long-term synaptic plasticity. J Neurosci 2003. [PMID: 12629184 DOI: 10.1523/jneurosci.23-05-01804.2003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Syntaxin has an important role in regulating vesicle docking and fusion essential for neurotransmitter release. Here, we demonstrate that the distribution of syntaxin mRNA in cell bodies of sensory neurons (SNs) of Aplysia maintained in cell culture is affected by synapse formation, synapse stabilization, and long-term facilitation (LTF) produced by 5-HT. The distribution of the mRNA in turn regulates expression and axonal transport of the protein. Syntaxin mRNA and protein accumulated at the axon hillock of SNs during the initial phase of synapse formation. Significant numbers of granules containing syntaxin were detected in the SN axon. When synaptic strength was stable, both mRNA and protein were targeted away from the axon hillock, and the number of syntaxin granules in the SN axon was reduced. Dramatic increases in mRNA and protein accumulation at the axon hillock and number of syntaxin granules in the SN axon were produced when cultures with stable connections were treated with 5-HT that evoked LTF. Anisomycin (protein synthesis inhibitor) or KT5720 (protein kinase A inhibitor) blocked LTF, accumulation of syntaxin mRNA and protein at the axon hillock, and the increase in syntaxin granules in SN axons. The results indicate that without significant effects on overall mRNA expression, both target interaction and 5-HT via activation of protein kinase A pathway regulate expression of syntaxin and its packaging for transport into axons by influencing the distribution of its mRNA in the SN cell body.
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Bozon B, Davis S, Laroche S. Regulated transcription of the immediate-early gene Zif268: mechanisms and gene dosage-dependent function in synaptic plasticity and memory formation. Hippocampus 2003; 12:570-7. [PMID: 12440572 DOI: 10.1002/hipo.10100] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The immediate-early gene Zif268 is a member of the Egr family of inducible transcription factors. Data from gene expression studies have suggested that this gene may play a critical role in initial triggering of the genetic machinery that has long been considered a necessary mechanism for maintenance of the later phases of LTP and also for the consolidation or stabilization of long-lasting memories. Until recently, however, the data supporting this assumption have been based primarily on circumstantial evidence, with no direct evidence to suggest that Zif268 is required for long-lasting synaptic plasticity and memory. In this report, we review our own data using Zif268 mutant mice; we show that although the early phase of dentate gyrus LTP is normal in these mice, the later phases are not present, and the ability of the mice to maintain learned information over a 24-h period is deficient. In addition, we present new information showing a task-dependent gene dosage effect in Zif268 heterozygous mice. We show that spatial learning is particularly sensitive to reduced levels of Zif268, as one-half of the complement of Zif268 in heterozygous mice is insufficient to maintain spatial long-term memories.
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Affiliation(s)
- Bruno Bozon
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, CNRS, UMR 8620, Université Paris-Sud, Orsay, France
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12
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Dubreuil D, Tixier C, Dutrieux G, Edeline JM. Does the radial arm maze necessarily test spatial memory? Neurobiol Learn Mem 2003; 79:109-17. [PMID: 12482685 DOI: 10.1016/s1074-7427(02)00023-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Since its design 25 years ago (Olton & Samuelson, 1976), the eight-arm radial maze has become very popular and is now widely used to assess spatial memory in rodents. Two versions of the full-baited maze protocol are present in the literature: with or without confinement between the visit of each arm. The confinement was introduced by Olton himself as early as 1977 (Olton, Collison, & Werz, 1977) to eliminate stereotypic behaviors that he had previously observed. It is widely regarded that the confinement prevents rodents from developing these response patterns, and as such it is considered an improved procedure to test spatial memory. Surprisingly, to the best of our knowledge, no study has been especially designed to demonstrate the efficacy of the confinement in blocking the stereotypic behaviors of the animals. The present study compares the strategies of rats trained with or without a confinement procedure. The results show that, after nine days of training, rats submitted to a 5- or a 10-s confinement reach the same level of performance as rats without confinement. The confinement totally prevents stereotypic behaviors like clockwise serial searching strategies which are often observed without confinement. Even a 0-s confinement is sufficient to prevent clockwise strategies, but rats seem to develop other stratagems which do not imply spatial memory. Furthermore, rats previously trained without confinement are unable to perform the task when confinement is introduced on a test day. In contrast, rats previously trained with confinement perform the task correctly when the confinement is no longer present. Thus, without confinement, good levels of performance can be achieved without precise spatial representations.
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Affiliation(s)
- Diane Dubreuil
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, UMR CNRS 8620, Université Paris-Sud, Bât 446, 91405 Orsay cedex, France
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13
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Chin LS, Vavalle JP, Li L. Staring, a novel E3 ubiquitin-protein ligase that targets syntaxin 1 for degradation. J Biol Chem 2002; 277:35071-9. [PMID: 12121982 DOI: 10.1074/jbc.m203300200] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Syntaxin 1 is an essential component of the neurotransmitter release machinery, and regulation of syntaxin 1 expression levels is thought to contribute to the mechanism underlying learning and memory. However, the molecular events that control the degradation of syntaxin 1 remain undefined. Here we report the identification and characterization of a novel RING finger protein, Staring, that interacts with syntaxin 1. Staring is expressed throughout the brain, where it exists in both cytosolic and membrane-associated pools. Staring binds and recruits the brain-enriched E2 ubiquitin-conjugating enzyme UbcH8 to syntaxin 1 and facilitates the ubiquitination and proteasome-dependent degradation of syntaxin 1. These findings suggest that Staring is a novel E3 ubiquitin-protein ligase that targets syntaxin 1 for degradation by the ubiquitin-proteasome pathway.
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Affiliation(s)
- Lih-Shen Chin
- Department of Pharmacology, Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322-3090, USA
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14
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Richter-Levin G, Yaniv D. Is LTP in the hippocampus a useful model for learning-related alterations in gene expression? Rev Neurosci 2002; 12:289-96. [PMID: 11560370 DOI: 10.1515/revneuro.2001.12.3.289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is well established that the formation of long-term memory requires de novo protein synthesis. Altered gene expression is therefore critical in the signal transduction cascade activated by the learning experience. Long-term potentiation (LTP) is a mnemonic model in which particular patterns of activation of incoming excitatory fibers (representing the learning experience) may induce long-lasting enhancement of the communication between the involved pre- and post-synapses (representing the memory). Therefore, cellular and molecular mechanisms of LTP have been extensively studied under the assumption that their understanding will contribute to our comprehension of the mechanisms underlying memory formation. In recent years, however, this analogy has been challenged by reports of inconsistency between LTP and memory. Here we assess LTP in the hippocampus as a model system to study spatial memory-related alterations in gene expression. We focus on three molecular families that are likely to play a role in synaptic plasticity: (1) synaptic communication related proteins; (2) signal transduction machinery; and (3) growth factors. Reviewing first the literature on LTP and then behavioral research we found both consistent and inconsistent findings regarding the LTP/memory linkage. The importance of restricting the discussion to both a learning phase and a brain (sub)structure, as well as of incorporating more physiological LTP stimulation protocols, is discussed. We conclude that while LTP is indeed limited as a model of memory, a careful use of it as a model system of synaptic plasticity is fruitful and productive in screening out candidate memory-related genes.
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15
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Génin A, Davis S, Meziane H, Doyère V, Jeromin A, Roder J, Mallet J, Laroche S. Regulated expression of the neuronal calcium sensor-1 gene during long-term potentiation in the dentate gyrus in vivo. Neuroscience 2002; 106:571-7. [PMID: 11591457 DOI: 10.1016/s0306-4522(01)00301-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Neuronal calcium sensor-1 (NCS-1), the mammalian homologue of frequenin, is a member of a highly conserved family of neuron-specific calcium-binding proteins which has been implicated in exocytosis and in multiple calcium-signalling pathways, suggesting a potential involvement in mechanisms of neuronal plasticity. Here, using in situ hybridization, we report an increased induction of the mRNA encoding NCS-1 in dentate granule cells following the induction of long-term potentiation in the awake rat. We show that NCS-1 mRNA levels are increased 1 and 3 h after long-term potentiation in an N-methyl-D-aspartate receptor-dependent manner, returning to baseline expression levels by 6 h. Electroconvulsive stimulation also induced NCS-1 mRNA transcription in the dentate gyrus, but at the different time of 6 h post-seizure, returning to baseline by 12 h. These results show that regulated expression of the NCS-1 gene is part of the transcriptional response associated with activity-dependent neuronal plasticity in vivo and suggest a molecular mechanism capable of mediating a functional change in synapse sensitivity to calcium and calcium-signalling pathways after long-term potentiation.
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Affiliation(s)
- A Génin
- Laboratoire de Génétique Moléculaire de la Neurotransmission et des Processus Neurodégénératifs, CNRS UMR C9923, Hôpital Pitié Salpêtrière, Paris, France
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16
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Subramaniam S, Marcotte ER, Srivastava LK. Differential changes in synaptic terminal protein expression between nucleus accumbens core and shell in the amphetamine-sensitized rat. Brain Res 2001; 901:175-83. [PMID: 11368965 DOI: 10.1016/s0006-8993(01)02347-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Repeated, intermittent administration of psychostimulant drugs such as D-amphetamine (AMPH) produces a state of behavioral sensitization to the drug that can last up to weeks to months. The molecular basis of this enhanced sensitivity to AMPH is poorly understood; however, adaptive changes in the mesocorticolimbic dopamine system has been postulated to be of primary importance. In the present investigation we used Western blotting to examine the expression of candidate presynaptic proteins involved in regulating neurotransmitter release and synaptic plasticity. Specifically, syntaxin 1, synaptophysin and synapsin I protein levels were examined in the nucleus accumbens (Nacc) and ventral tegmental area (VTA) of Sprague-Dawley rats following AMPH-sensitization. Animals received five repeated administrations of AMPH (1.5 mg/kg, i.p. on alternate days) followed by 14 days of withdrawal. Levels of syntaxin 1 and synaptophysin were found to be significantly reduced in the Nacc core of sensitized animals compared to saline-treated and untreated controls. However, syntaxin 1 expression was significantly increased in the Nacc shell subregion of sensitized animals. No significant difference in the level of synapsin I was noted in any of the brain regions. Further, expression of none of the synaptic proteins was significantly altered in the VTA of sensitized animals. Given the importance of syntaxin and synaptophysin in learning and memory processes and in the regulation of neurotransmitter release, changes in these proteins suggest their involvement in the associative learning aspects of sensitization and differential neurotransmitter release in the Nacc subregions.
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Affiliation(s)
- S Subramaniam
- Departments of Psychiatry and Neurology and Neurosurgery, Douglas Hospital Research Centre, McGill University, 6875 LaSalle Boulevard, Verdun, Montreal, Quebec H4H 1R3, Canada
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17
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Laroche S, Davis S, Jay TM. Plasticity at hippocampal to prefrontal cortex synapses: dual roles in working memory and consolidation. Hippocampus 2001; 10:438-46. [PMID: 10985283 DOI: 10.1002/1098-1063(2000)10:4<438::aid-hipo10>3.0.co;2-3] [Citation(s) in RCA: 255] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The involvement of the hippocampus and the prefrontal cortex in cognitive processes and particularly in learning and memory has been known for a long time. However, the specific role of the projection which connects these two structures has remained elusive. The existence of a direct monosynaptic pathway from the ventral CA1 region of the hippocampus and subiculum to specific areas of the prefrontal cortex provides a useful model for conceptualizing the functional operations of hippocampal-prefrontal cortex communication in learning and memory. It is known now that hippocampal to prefrontal cortex synapses are modifiable synapses and can express different forms of plasticity, including long-term potentiation, long-term depression, and depotentiation. Here we review these findings and focus on recent studies that start to relate synaptic plasticity in the hippocampo-prefrontal cortex pathway to two specific aspects of learning and memory, i.e., the consolidation of information and working memory. The available evidence suggests that functional interactions between the hippocampus and prefrontal cortex in cognition and memory are more complex than previously anticipated, with the possibility for bidirectional regulation of synaptic strength as a function of the specific demands of tasks.
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Affiliation(s)
- S Laroche
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, CNRS UMR 8620, Université Paris-Sud, Orsay, France.
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18
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Davis S, Salin H, Helme-Guizon A, Dumas S, Stéphan A, Corbex M, Mallet J, Laroche S. Dysfunctional regulation of alphaCaMKII and syntaxin 1B transcription after induction of LTP in the aged rat. Eur J Neurosci 2000; 12:3276-82. [PMID: 10998111 DOI: 10.1046/j.1460-9568.2000.00193.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Syntaxin 1B and alphaCaMKII are two genes that are upregulated after the induction of LTP and appear to underlie different mechanisms of synaptic plasticity. alphaCaMKII is directly implicated in strengthening the synapses that have been modified, whereas syntaxin 1B has been implicated in a mechanism for the propagation of synaptic plasticity within neural circuits. In these experiments we have investigated whether the regulation of these genes is altered after the induction of LTP in aged rats. We found, three hours after the induction of LTP in the dentate gyrus, that aged rats could be subgrouped into those in which LTP was maintained and those in which LTP had decayed back to basal levels. Both genes were upregulated in young adult rats, whereas there was a differential pattern of LTP-induced expression in the aged rats. Dendritic alphaCaMKII was upregulated in aged rats only when LTP was maintained. In contrast, regulation of syntaxin 1B and alphaCaMKII was absent in the granule cell bodies of the aged rats regardless of whether LTP was maintained or not. These results suggest that molecular mechanisms implicated in two aspects of hippocampal synaptic plasticity malfunction during normal ageing and therefore may have some contributory role in the decline in memory function routinely observed in ageing.
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Affiliation(s)
- S Davis
- Laboratoire de Neurobiologie de l'Apprentissage, de la Mémoire et de la Communication, CNRS UMR 8620, Bât 446, Université Paris Sud, 91405 Orsay, France.
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19
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Nakahara T, Nakamura K, Tsutsumi T, Hashimoto K, Hondo H, Hisatomi S, Motomura K, Uchimura H. Effect of chronic haloperidol treatment on synaptic protein mRNAs in the rat brain. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1998; 61:238-42. [PMID: 9795234 DOI: 10.1016/s0169-328x(98)00230-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Chronic haloperidol treatment caused significant decreases in the levels of synaptotagmin I and IV, synaptobrevin II, syntaxin 1A and Rab 3A mRNAs in the nucleus accumbens but not in the prefrontal cortex medial field, striatum, substantia nigra and ventral tegmental area. No significant changes in SNAP 25 and synaptophysin mRNA levels were observed in any brain region examined. The reduced expression of synaptic proteins may be related to haloperidol-induced depolarization block of mesolimbic dopamine neurons.
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Affiliation(s)
- T Nakahara
- Department of Chemistry, Faculty of Science, Kyushu University, Ropponmatsu, Fukuoka 810-8560, Japan.
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20
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Davis S, Rodger J, Stéphan A, Hicks A, Mallet J, Laroche S. Increase in Syntaxin 1B mRNA in Hippocampal and Cortical Circuits During Spatial Learning Reflects a Mechanism of Trans-synaptic Plasticity Involved in Establishing a Memory Trace. Learn Mem 1998. [DOI: 10.1101/lm.5.4.375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
It has long been proposed that the cellular and molecular mechanisms responsible for LTP may well involve the mechanisms that lead to the type of synaptic modification that occurs during learning. However, it is also known that a single memory trace is encoded in spatially distributed networks; implying that alterations of synaptic strength occur at multiple sites along circuits of connected cells. Recent evidence suggests that regulation of the gene encoding syntaxin 1B, a presynaptic protein involved in exocytosis, plays an important role in the mediation of trans-synaptic LTP, a candidate mechanism for the propagation of plasticity in neural circuits during learning. Using in situ hybridization to measure the mRNA levels at different time points after learning a spatial working or reference memory task, we show that expression of the gene encoding this protein in the hippocampal and corticoprefrontal circuits increases linearly with performance at a critical window of learning when rats are reaching between 75% and 100% of their maximal performance. No changes were observed during the early phases of learning or when rats where overtrained. The correlational analysis indicates that coordinated increases in syntaxin 1B expression occurs in hippocampal circuits during working memory and in more widespread hippocampocortical circuits during reference memory. These results suggest that a form of trans-synaptic plasticity mediated in part by regulation of the expression of syntaxin 1B may play an active role in configuring specific spatially distributed circuits during the laying down of memories.
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21
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Richter-Levin G, Thomas KL, Hunt SP, Bliss TV. Dissociation between genes activated in long-term potentiation and in spatial learning in the rat. Neurosci Lett 1998; 251:41-4. [PMID: 9714460 DOI: 10.1016/s0304-3940(98)00476-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have compared changes in mRNA of three genes, zif268, raf B, and syntaxin 1 B, following the unilateral induction of long-term potentiation (LTP) in rats previously trained in a water maze, and in behaviourally naive animals. mRNA of all three genes was enhanced in the potentiated dentate gyrus of naive animals 3 h after the induction of LTP. Training did not affect expression of mRNA for zif268 or for syntaxin 1 B. Expression of raf B was enhanced by training, and in trained animals the LTP-associated increase in expression of raf B was occluded. These results suggest that LTP and spatial training engage a common pathway utilizing an increase in mRNA for raf B, and demonstrate a dissociation between LTP and spatial learning with respect to expression of zif268 and syntaxin 1B.
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Affiliation(s)
- G Richter-Levin
- Division of Neurophysiology, National Institute for Medical Research, London, UK.
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22
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Helme-Guizon A, Davis S, Israel M, Lesbats B, Mallet J, Laroche S, Hicks A. Increase in syntaxin 1B and glutamate release in mossy fibre terminals following induction of LTP in the dentate gyrus: a candidate molecular mechanism underlying transsynaptic plasticity. Eur J Neurosci 1998; 10:2231-7. [PMID: 9749751 DOI: 10.1046/j.1460-9568.1998.00232.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A growing body of evidence suggests that modulation of certain proteins of the exocytotic machinery is, in part, involved in the biochemical changes that underlie long-term synaptic plasticity. We have previously shown that the induction of long-term potentiation (LTP) at perforant path to dentate granule cell synapses in the rat hippocampus induces changes in the mRNA levels of syntaxin 1B and synapsin I, known to be involved in neurotransmitter release. Immunohistochemical staining suggested that concomitant changes in these proteins occurred at mossy fibre synapses, downstream of those synapses at which LTP was induced, leading us to postulate that such a mechanism might underlie a form of transsynaptic plasticity. Here we have used a specific mossy-fibre synaptosome preparation to quantify levels of proteins and measure, using a chemiluminescent glutamate assay, depolarization-induced glutamate release from these synaptosomes after induction of LTP in the dentate gyrus in vivo. We show that 5 h after the induction of LTP, there is an increase in the protein levels of syntaxin 1B and, although to a lesser extent, the synapsins I and II, associated with an increase in depolarization-induced release of glutamate within these terminals. Increases in both the protein levels and glutamate release were not observed when dentate gyrus LTP was blocked by an NMDA receptor antagonist. From these results we propose a molecular mechanism for the propagation of synaptic plasticity through hippocampal circuits.
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Affiliation(s)
- A Helme-Guizon
- Laboratoire de Neurobiologie de l'Apprentissage et de la Mémoire, CNRS URA 1491, Université Paris Sud, Orsay, France
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23
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Davis S, Laroche S. A molecular biological approach to synaptic plasticity and learning. COMPTES RENDUS DE L'ACADEMIE DES SCIENCES. SERIE III, SCIENCES DE LA VIE 1998; 321:97-107. [PMID: 9759327 DOI: 10.1016/s0764-4469(97)89808-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Until the more recent advances made in molecular biology, attempts to link synaptic plasticity and learning have focused on using LTP as a marker of learning-induced synaptic plasticity, where one has expected to observe the same magnitude of change in synaptic strength as that observed with artificial stimulation. To a large extent this approach has been frustrated by the fact that it is generally assumed that the representation of the memory traces is distributed throughout widespread networks of cells. By implication it is more likely that one would observe small distributed changes within a network; a formidable task to measure. In this review we describe how the advances in molecular biology give us both the tools to investigate the mechanisms of synaptic plasticity and to apply these to investigations of the underlying mechanisms in learning and the formation of memories that have until now remained out of our grasp.
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Affiliation(s)
- S Davis
- Laboratoire de neurobiologie de l'apprentissage et de la mémoire, CNRS Ura 1491, université Paris-Sud, Orsay, France.
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24
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Hicks A, Davis S, Rodger J, Helme-Guizon A, Laroche S, Mallet J. Synapsin I and syntaxin 1B: key elements in the control of neurotransmitter release are regulated by neuronal activation and long-term potentiation in vivo. Neuroscience 1997; 79:329-40. [PMID: 9200718 DOI: 10.1016/s0306-4522(96)00700-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The messenger RNAs encoding proteins of the exocytotic machinery were measured at different times following the induction of long-term potentiation or increasing neuronal activity in the dentate gyrus of the rat in vivo. In situ hybridization revealed that from the many messenger RNAs that encode proteins involved in regulated exocytosis, only those encoding synapsin I and syntaxin 1B were specifically increased. The levels of messenger RNA encoding both synapsin I and syntaxin 1B were increased on the ipsilateral side of the dorsal dentate gyrus 2 and 5 h following the induction of long-term potentiation. Syntaxin 1B was also increased in the ventral dentate gyrus at the same time-points. On the contralateral side of the dentate gyrus there was an increase in both synapsin I and syntaxin 1B at 5 h only. All of these long-term potentiation-induced changes were prevented when the tetanus was delivered in the presence of the N-methyl-D-aspartate receptor antagonist. (D(-)-2-amino-5-phosphonopentanoic acid. Immunocytochemical staining revealed that protein levels for both synapsin I and syntaxin 1B were elevated in the mossy fibre terminal zone of CA3 5 h after the induction of long-term potentiation. In addition to these plasticity-induced changes, a transient increase in the messenger RNA encoding syntaxin 1B was observed at 2 h in conditions of high intensity stimulation of the perforant path to increase the level of cellular activation, but this change was not maintained even when high intensity stimulation was sustained for 5 h. No changes in either of the messenger RNAs were observed under low frequency stimulation and pseudotetanus at either time-points. These results show that an overall increase in neuronal excitation within a neuronal network can be differentiated from a change in synaptic strength at a specific subset of the synapses, where only synaptic plasticity leads to long-term changes in the expression of selective members of the exocytotic machinery. Altered concentrations of key vesicle proteins may thus provide the means for modulation of neurotransmitter release over long time-periods. The persistent long-term potentiation-induced postsynaptic increase in messenger RNAs encoding these presynaptic proteins has important implications for the propagation of signals downstream from the site of long-term potentiation induction in hippocampal neural networks, and highlights a candidate molecular mechanism for mediating the propagation of synaptic plasticity in such networks.
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Affiliation(s)
- A Hicks
- Laboratoire de Génétique Moléculaire de la Neurotransmission et des Processus Neurodégénératifs, CNRS UMR C9923, Hôpital de la Pitié Salpêtrière, Paris, France
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