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Borland JM. The effects of different types of social interactions on the electrophysiology of neurons in the nucleus accumbens in rodents. Neurosci Biobehav Rev 2024; 164:105809. [PMID: 39004323 DOI: 10.1016/j.neubiorev.2024.105809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 07/16/2024]
Abstract
BORLAND, J.M., The effects of different types of social interactions on the electrophysiology of neurons in the nucleus accumbens in rodents, NEUROSCI BIOBEH REV 21(1) XXX-XXX, 2024.-Sociality shapes an organisms' life. The nucleus accumbens is a critical brain region for mental health. In the following review, the effects of different types of social interactions on the physiology of neurons in the nucleus accumbens is synthesized. More specifically, the effects of sex behavior, aggression, social defeat, pair-bonding, play behavior, affiliative interactions, parental behaviors, the isolation from social interactions and maternal separation on measures of excitatory synaptic transmission, intracellular signaling and factors of transcription and translation in neurons in the nucleus accumbens in rodent models are reviewed. Similarities and differences in effects depending on the type of social interaction is then discussed. This review improves the understanding of the molecular and synaptic mechanisms of sociality.
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Miranda M, Silva A, Morici JF, Coletti MA, Belluscio M, Bekinschtein P. Retrieval of contextual memory can be predicted by CA3 remapping and is differentially influenced by NMDAR activity in rat hippocampus subregions. PLoS Biol 2024; 22:e3002706. [PMID: 38950066 PMCID: PMC11244845 DOI: 10.1371/journal.pbio.3002706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 07/12/2024] [Accepted: 06/12/2024] [Indexed: 07/03/2024] Open
Abstract
Episodic memory is essential to navigate in a changing environment by recalling past events, creating new memories, and updating stored information from experience. Although the mechanisms for acquisition and consolidation have been profoundly studied, much less is known about memory retrieval. Hippocampal spatial representations are key for retrieval of contextually guided episodic memories. Indeed, hippocampal place cells exhibit stable location-specific activity which is thought to support contextual memory, but can also undergo remapping in response to environmental changes. It is unclear if remapping is directly related to the expression of different episodic memories. Here, using an incidental memory recognition task in rats, we showed that retrieval of a contextually guided memory is reflected by the levels of CA3 remapping, demonstrating a clear link between external cues, hippocampal remapping, and episodic memory retrieval that guides behavior. Furthermore, we describe NMDARs as key players in regulating the balance between retrieval and memory differentiation processes by controlling the reactivation of specific memory traces. While an increase in CA3 NMDAR activity boosts memory retrieval, dentate gyrus NMDAR activity enhances memory differentiation. Our results contribute to understanding how the hippocampal circuit sustains a flexible balance between memory formation and retrieval depending on the environmental cues and the internal representations of the individual. They also provide new insights into the molecular mechanisms underlying the contributions of hippocampal subregions to generate this balance.
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Affiliation(s)
- Magdalena Miranda
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Azul Silva
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Juan Facundo Morici
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Marcos Antonio Coletti
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Mariano Belluscio
- Laboratorio Bases neuronales del comportamiento, Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- CONICET—Universidad de Buenos Aires, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay), Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Pedro Bekinschtein
- Laboratorio de Memoria y Cognición Molecular, Instituto de Neurociencia Cognitiva y Traslacional, CONICET-Fundación INECO-Universidad Favaloro, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
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3
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Franco-Pérez J. Mechanisms Underlying Memory Impairment Induced by Fructose. Neuroscience 2024; 548:27-38. [PMID: 38679409 DOI: 10.1016/j.neuroscience.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/04/2024] [Accepted: 04/03/2024] [Indexed: 05/01/2024]
Abstract
Fructose consumption has increased over the years, especially in adolescents living in urban areas. Growing evidence indicates that daily fructose consumption leads to some pathological conditions, including memory impairment. This review summarizes relevant data describing cognitive deficits after fructose intake and analyzes the underlying neurobiological mechanisms. Preclinical experiments show sex-related deficits in spatial memory; that is, while males exhibit significant imbalances in spatial processing, females seem unaffected by dietary supplementation with fructose. Recognition memory has also been evaluated; however, only female rodents show a significant decline in the novel object recognition test performance. According to mechanistic evidence, fructose intake induces neuroinflammation, mitochondrial dysfunction, and oxidative stress in the short term. Subsequently, these mechanisms can trigger other long-term effects, such as inhibition of neurogenesis, downregulation of trophic factors and receptors, weakening of synaptic plasticity, and long-term potentiation decay. Integrating all these neurobiological mechanisms will help us understand the cellular and molecular processes that trigger the memory impairment induced by fructose.
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Affiliation(s)
- Javier Franco-Pérez
- Laboratorio Patología Vascular Cerebral, Instituto Nacional de Neurología y Neurocirugía, Manuel Velasco Suárez, Insurgentes Sur 3877, Col. La Fama, C.P. 14269, CDMX, México, Mexico.
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4
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Pitzer EM, Sugimoto C, Regan SL, Gudelsky GA, Williams MT, Vorhees CV. Developmental deltamethrin: Sex-specific hippocampal effects in Sprague Dawley rats. Curr Res Toxicol 2022; 3:100093. [PMID: 36393872 PMCID: PMC9661443 DOI: 10.1016/j.crtox.2022.100093] [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: 08/16/2022] [Revised: 10/04/2022] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
Abstract
Pyrethroid pesticides are widely used and can cause long-term effects after early exposure. Epidemiological and animal studies reveal associations between pyrethroid exposure and altered cognition following prenatal and/or neonatal exposure. However, little is known about the cellular effects of such exposure. Sprague Dawley rats were gavaged with 0 or 1.0 mg/kg deltamethrin (DLM), a Type II pyrethroid, in corn oil (dose volume 5 mL/kg) once per day from postnatal day (P) 3-20 and assessed shortly after dosing ended or as adults. No effects of DLM exposure were found on striatal dopaminergic markers, nor on AMPA receptor subunits or on NMDA-NR1. However, DLM increased NMDA-NR2A and decreased NMDA-NR2B levels in the hippocampus, in males but not females. Additionally, adult hippocampal CA1 long-term potentiation was increased in DLM-treated males but not females. Potassium stimulated extracellular glutamate release in the hippocampus was not affected using in vivo microdialysis. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) showed increased apoptotic cells in the dentate gyrus of male rats, in the absence of changes in cleaved caspase-3 at P21. Proinflammatory cytokines interferon gamma trended up in striatum, interleukin-1β trended down in nucleus accumbens, IL-13 trended up in hippocampus, and keratinocyte chemoattractant/human growth-regulated oncogene (KC/GRO or CXCL1) was significantly increased in the hippocampus in male DLM-treated rats on P20. The data point to the developing hippocampus as a susceptible region to DLM-induced adverse effects.
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Affiliation(s)
- Emily M. Pitzer
- Dept. of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Chiho Sugimoto
- Dept. of Physiology, Michigan State University, 766 Service Rd. 5401 Interdisciplinary Science and Technology Building, East Lansing, MI 48824, USA
| | - Samantha L. Regan
- Dept. of Human Genetics, University of Michigan Medical Center, 3703 Med Sci II, 1241 E. Catherine St., Ann Arbor, MI 48109-5618, USA
| | - Gary A. Gudelsky
- College of Pharmacy, Div. of Pharmaceutical Sciences, 3212 Medical Sciences Building, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Michael T. Williams
- Dept. of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Charles V. Vorhees
- Dept. of Pediatrics, University of Cincinnati College of Medicine, and Division of Neurology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
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5
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Martos D, Tuka B, Tanaka M, Vécsei L, Telegdy G. Memory Enhancement with Kynurenic Acid and Its Mechanisms in Neurotransmission. Biomedicines 2022; 10:biomedicines10040849. [PMID: 35453599 PMCID: PMC9027307 DOI: 10.3390/biomedicines10040849] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 03/28/2022] [Accepted: 04/02/2022] [Indexed: 02/04/2023] Open
Abstract
Kynurenic acid (KYNA) is an endogenous tryptophan (Trp) metabolite known to possess neuroprotective property. KYNA plays critical roles in nociception, neurodegeneration, and neuroinflammation. A lower level of KYNA is observed in patients with neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases or psychiatric disorders such as depression and autism spectrum disorders, whereas a higher level of KYNA is associated with the pathogenesis of schizophrenia. Little is known about the optimal concentration for neuroprotection and the threshold for neurotoxicity. In this study the effects of KYNA on memory functions were investigated by passive avoidance test in mice. Six different doses of KYNA were administered intracerebroventricularly to previously trained CFLP mice and they were observed for 24 h. High doses of KYNA (i.e., 20–40 μg/2 μL) significantly decreased the avoidance latency, whereas a low dose of KYNA (0.5 μg/2 μL) significantly elevated it compared with controls, suggesting that the low dose of KYNA enhanced memory function. Furthermore, six different receptor blockers were applied to reveal the mechanisms underlying the memory enhancement induced by KYNA. The series of tests revealed the possible involvement of the serotonergic, dopaminergic, α and β adrenergic, and opiate systems in the nootropic effect. This study confirmed that a low dose of KYNA improved a memory component of cognitive domain, which was mediated by, at least in part, four systems of neurotransmission in an animal model of learning and memory.
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Affiliation(s)
- Diána Martos
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, H-6725 Szeged, Hungary; (D.M.); (B.T.); (M.T.)
| | - Bernadett Tuka
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, H-6725 Szeged, Hungary; (D.M.); (B.T.); (M.T.)
| | - Masaru Tanaka
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, H-6725 Szeged, Hungary; (D.M.); (B.T.); (M.T.)
| | - László Vécsei
- MTA-SZTE Neuroscience Research Group, Hungarian Academy of Sciences, University of Szeged (MTA-SZTE), Semmelweis u. 6, H-6725 Szeged, Hungary; (D.M.); (B.T.); (M.T.)
- Department of Neurology, Albert Szent-Györgyi Medical School, University of Szeged, Semmelweis u. 6, H-6725 Szeged, Hungary
- Correspondence: ; Tel.: +36-62-342-361
| | - Gyula Telegdy
- Department of Pathophysiology, Albert Szent-Györgyi Medical School, University of Szeged, Semmelweis u. 5, H-6725 Szeged, Hungary;
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6
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George H, Bashir ZI, Hussain S. Impaired hippocampal NMDAR-LTP in a transgenic model of NSUN2-deficiency. Neurobiol Dis 2022; 163:105597. [PMID: 34954053 DOI: 10.1016/j.nbd.2021.105597] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/09/2021] [Accepted: 12/19/2021] [Indexed: 11/28/2022] Open
Abstract
Biallelic loss-of-function NSUN2 mutations have recently been associated with cases of Autism Spectrum Condition (ASC), and NSun2-deficiency was also previously shown to cause a severe autosomal recessive intellectually disability disorder syndrome in which patients can sometimes display autistic behaviour. It has been demonstrated that NSUN2 can control protein synthesis rates via direct regulation of RNA methylation, and it is therefore of interest that other studies have suggested protein synthesis-dependent synaptic plasticity dysregulation as a mechanism for learning difficulties in various other autism-expressing conditions and disorders. Here we investigated NMDAR-LTP in a murine transgenic model harbouring loss-of-function mutation in the NSun2 gene and find an impairment of a protein synthesis-dependent form of this synaptic plasticity pathway. Our findings support the idea that NMDAR-LTP mis-regulation may represent a previously underappreciated mechanism associated with autism phenotypes.
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Affiliation(s)
- Harry George
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK; Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Zafar I Bashir
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol BS8 1TD, UK.
| | - Shobbir Hussain
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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7
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Livingstone RW, Elder MK, Singh A, Westlake CM, Tate WP, Abraham WC, Williams JM. Secreted Amyloid Precursor Protein-Alpha Enhances LTP Through the Synthesis and Trafficking of Ca 2+-Permeable AMPA Receptors. Front Mol Neurosci 2021; 14:660208. [PMID: 33867938 PMCID: PMC8047154 DOI: 10.3389/fnmol.2021.660208] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/10/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of AMPA receptor expression by neuronal activity and neuromodulators is critical to the expression of both long-term potentiation (LTP) and memory. In particular, Ca2+-permeable AMPARs (CP-AMPAR) play a unique role in these processes due to their transient, activity-regulated expression at synapses. Secreted amyloid precursor protein-alpha (sAPPα), a metabolite of the parent amyloid precursor protein (APP) has been previously shown to enhance hippocampal LTP as well as memory formation in both normal animals and in Alzheimer’s disease models. In earlier work we showed that sAPPα promotes trafficking of GluA1-containing AMPARs to the cell surface and specifically enhances synthesis of GluA1. To date it is not known whether de novo synthesized GluA1 form CP-AMPARs or how they contribute to sAPPα-mediated plasticity. Here, using fluorescent non-canonical amino acid tagging–proximity ligation assay (FUNCAT-PLA), we show that brief treatment of primary rat hippocampal neurons with sAPPα (1 nM, 30 min) rapidly enhanced the cell-surface expression of de novo GluA1 homomers and reduced levels of de novo GluA2, as well as extant GluA2/3-AMPARs. The de novo GluA1-containing AMPARs were localized to extrasynaptic sites and later internalized by sAPPα-driven expression of the activity-regulated cytoskeletal-associated protein, Arc. Interestingly, longer exposure to sAPPα increased synaptic levels of GluA1/2 AMPARs. Moreover, the sAPPα-mediated enhancement of LTP in area CA1 of acute hippocampal slices was dependent on CP-AMPARs. Together, these findings show that sAPPα engages mechanisms which specifically enhance the synthesis and cell-surface expression of GluA1 homomers, underpinning the sAPPα-driven enhancement of synaptic plasticity in the hippocampus.
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Affiliation(s)
- Rhys W Livingstone
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Megan K Elder
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Anurag Singh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Courteney M Westlake
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Warren P Tate
- Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Joanna M Williams
- Department of Anatomy, Brain Health Research Centre, Brain Research New Zealand - Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
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8
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Sumner RL, Spriggs MJ, Shaw AD. Modelling thalamocortical circuitry shows that visually induced LTP changes laminar connectivity in human visual cortex. PLoS Comput Biol 2021; 17:e1008414. [PMID: 33476341 PMCID: PMC7853500 DOI: 10.1371/journal.pcbi.1008414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 02/02/2021] [Accepted: 10/05/2020] [Indexed: 11/19/2022] Open
Abstract
Neuroplasticity is essential to learning and memory in the brain; it has therefore also been implicated in numerous neurological and psychiatric disorders, making measuring the state of neuroplasticity of foremost importance to clinical neuroscience. Long-term potentiation (LTP) is a key mechanism of neuroplasticity and has been studied extensively, and invasively in non-human animals. Translation to human application largely relies on the validation of non-invasive measures of LTP. The current study presents a generative thalamocortical computational model of visual cortex for investigating and replicating interlaminar connectivity changes using non-invasive EEG recording of humans. The model is combined with a commonly used visual sensory LTP paradigm and fit to the empirical EEG data using dynamic causal modelling. The thalamocortical model demonstrated remarkable accuracy recapitulating post-tetanus changes seen in invasive research, including increased excitatory connectivity from thalamus to layer IV and from layer IV to II/III, established major sites of LTP in visual cortex. These findings provide justification for the implementation of the presented thalamocortical model for ERP research, including to provide increased detail on the nature of changes that underlie LTP induced in visual cortex. Future applications include translating rodent findings to non-invasive research in humans concerning deficits to LTP that may underlie neurological and psychiatric disease. The brain’s ability to learn and form memories is governed by neuroplasticity. One of the major mechanisms of neuroplasticity is long-term potentiation (LTP). To study LTP in detail necessitates implanting electrodes in the brain of non-human animals. However, to translate this knowledge to humans requires a non-invasive method. Neural mass models use mathematical equations to describe the brain’s neural architecture and function over time. Fitting these models to real data, using methods such as dynamic causal modelling (DCM), helps to elucidate the connectivity and major channel changes that could have plausibly caused the observed effects in electroencephalography data recorded non-invasively from the scalp. The current study presents a thalamocortical model of the neural architecture of the visual system combined with a thalamic compartment. The model is able to represent the basic transfer of visual information to the cortex, mediated by major receptor types. We combined the thalamocortical model with a visual processing task that uses black and white grating images to induce and measure LTP in visual cortex. We hypothesised that the changes in the model would be consistent with what is seen in animal invasive recordings. The model demonstrated remarkable accuracy in recapitulating changes to neural architecture consistent with the induction of LTP in visual cortex. Additionally, the result demonstrated specificity to the visual input that induced LTP. Future applications include translating animal findings that are beginning to determine how disordered LTP may underlie neurological and psychiatric disease (for example depression, schizophrenia, autism, and dementia).
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Affiliation(s)
- Rachael L. Sumner
- School of Pharmacy, University of Auckland, Auckland, New Zealand
- * E-mail:
| | - Meg J. Spriggs
- Centre for Psychedelic Research, Department of Medicine, Imperial College London, London, United Kingdom
| | - Alexander D. Shaw
- Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom
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9
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Evans HT, Blackmore D, Götz J, Bodea LG. De novo proteomic methods for examining the molecular mechanisms underpinning long-term memory. Brain Res Bull 2021; 169:94-103. [PMID: 33465403 DOI: 10.1016/j.brainresbull.2020.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 12/07/2020] [Accepted: 12/21/2020] [Indexed: 01/19/2023]
Abstract
Memory formation is a fundamental function of the nervous system that enables the experience-based adaptation of behaviour. The formation, recall and updating of long-term memory (LTM) requires new protein synthesis through its direct involvement in neuronal processes, such as long-term potentiation (LTP), long-term depression (LTD) and synaptic scaling. We discuss the advantages and limitations of several emerging techniques which enable the tagging of newly synthesised proteins, including stable isotope labelling with amino acids in cell culture (SILAC), puromycin labelling, and non-canonical amino acid (NCAA) labelling. We further present how these methods allow for the identification and visualisation of proteins which are newly synthesised during different stages of memory formation. These emerging techniques will continue to expand our understanding of how memories are formed, consolidated and retrieved.
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Affiliation(s)
- Harrison Tudor Evans
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia
| | - Daniel Blackmore
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia
| | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia.
| | - Liviu-Gabriel Bodea
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia.
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10
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Sateesh S, Abraham WC. Neurophysiological and molecular approaches to understanding the mechanisms of learning and memory. J R Soc N Z 2020. [DOI: 10.1080/03036758.2020.1796719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Shruthi Sateesh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Wickliffe C. Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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11
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Sumner RL, Spriggs MJ, Muthukumaraswamy SD, Kirk IJ. The role of Hebbian learning in human perception: a methodological and theoretical review of the human Visual Long-Term Potentiation paradigm. Neurosci Biobehav Rev 2020; 115:220-237. [PMID: 32562886 DOI: 10.1016/j.neubiorev.2020.03.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/02/2020] [Accepted: 03/12/2020] [Indexed: 11/17/2022]
Abstract
Long-term potentiation (LTP) is one of the most widely studied forms of neural plasticity, and is thought to be the principle mechanism underlying long-term memory and learning in the brain. Sensory paradigms utilising electroencephalography (EEG) and sensory stimulation to induce LTP have allowed translation from rodent and primate invasive research to non-invasive human investigations. This review focusses on visual sensory LTP induced using repetitive visual stimulation, resulting in changes in the visually evoked response recorded at the scalp with EEG. Across 15 years of use and replication in humans several major paradigm variants for eliciting visual LTP have emerged. The application of different paradigms, and the broad implementation of visual LTP across different populations combines to provide a rich and sensitive account of Hebbian LTP, and potentially non-Hebbian plasticity mechanisms. This review will conclude with a discussion of how these findings have advanced existing theories of perceptual learning by positioning Hebbian learning both alongside and within other major theories such as Predictive Coding and The Free Energy Principle.
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Affiliation(s)
| | - Meg J Spriggs
- Centre for Psychedelic Research, Division of Brain Sciences, Centre for Psychiatry, Imperial College London, UK
| | | | - Ian J Kirk
- Brain Research, New Zealand; School of Psychology, University of Auckland, New Zealand
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12
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Cheyne JE, Montgomery JM. The cellular and molecular basis of in vivo synaptic plasticity in rodents. Am J Physiol Cell Physiol 2020; 318:C1264-C1283. [PMID: 32320288 DOI: 10.1152/ajpcell.00416.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasticity within the neuronal networks of the brain underlies the ability to learn and retain new information. The initial discovery of synaptic plasticity occurred by measuring synaptic strength in vivo, applying external stimulation and observing an increase in synaptic strength termed long-term potentiation (LTP). Many of the molecular pathways involved in LTP and other forms of synaptic plasticity were subsequently uncovered in vitro. Over the last few decades, technological advances in recording and imaging in live animals have seen many of these molecular mechanisms confirmed in vivo, including structural changes both pre- and postsynaptically, changes in synaptic strength, and changes in neuronal excitability. A well-studied aspect of neuronal plasticity is the capacity of the brain to adapt to its environment, gained by comparing the brains of deprived and experienced animals in vivo, and in direct response to sensory stimuli. Multiple in vivo studies have also strongly linked plastic changes to memory by interfering with the expression of plasticity and by manipulating memory engrams. Plasticity in vivo also occurs in the absence of any form of external stimulation, i.e., during spontaneous network activity occurring with brain development. However, there is still much to learn about how plasticity is induced during natural learning and how this is altered in neurological disorders.
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Affiliation(s)
- Juliette E Cheyne
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Johanna M Montgomery
- Department of Physiology and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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13
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Zhao J, Fok AHK, Fan R, Kwan PY, Chan HL, Lo LHY, Chan YS, Yung WH, Huang J, Lai CSW, Lai KO. Specific depletion of the motor protein KIF5B leads to deficits in dendritic transport, synaptic plasticity and memory. eLife 2020; 9:53456. [PMID: 31961321 PMCID: PMC7028368 DOI: 10.7554/elife.53456] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/20/2020] [Indexed: 12/16/2022] Open
Abstract
The kinesin I family of motor proteins are crucial for axonal transport, but their roles in dendritic transport and postsynaptic function are not well-defined. Gene duplication and subsequent diversification give rise to three homologous kinesin I proteins (KIF5A, KIF5B and KIF5C) in vertebrates, but it is not clear whether and how they exhibit functional specificity. Here we show that knockdown of KIF5A or KIF5B differentially affects excitatory synapses and dendritic transport in hippocampal neurons. The functional specificities of the two kinesins are determined by their diverse carboxyl-termini, where arginine methylation occurs in KIF5B and regulates its function. KIF5B conditional knockout mice exhibit deficits in dendritic spine morphogenesis, synaptic plasticity and memory formation. Our findings provide insights into how expansion of the kinesin I family during evolution leads to diversification and specialization of motor proteins in regulating postsynaptic function. Transporting molecules within a cell becomes a daunting task when the cell is a neuron, with fibers called axons and dendrites that can stretch as long as a meter. Neurons use many different molecules to send messages across the body and store memories in the brain. If the right molecules cannot be delivered along the length of nerve cells, connections to neighboring neurons may decay, which may impair learning and memory. Motor proteins are responsible for transporting molecules within cells. Kinesins are a type of motor protein that typically transports materials from the body of a neuron to the cell’s periphery, including the dendrites, which is where a neuron receives messages from other nerve cells. Each cell has up to 45 different kinesin motors, but it is not known whether each one performs a distinct task or if they have overlapping roles. Now, Zhao, Fok et al. have studied two similar kinesins, called KIF5A and KIF5B, in rodent neurons to determine their roles. First, it was shown that both proteins were found at dendritic spines, which are small outgrowths on dendrites where contact with other cells occurs. Next, KIF5A and KIF5B were depleted, one at a time, from neurons extracted from a brain region called the hippocampus. Removing KIF5B interfered with the formation of dendritic spines, but removing KIF5A did not have an effect. Dendritic spines are essential for learning and memory, so several behavioral tests were conducted on mice that had been genetically modified to express less KIF5B in the forebrain. These tests revealed that the mice performed poorly in tasks that tested their memory recall. This work opens a new area of research studying the specific roles of different kinesin motor proteins in nerve cells. This could have important implications because certain kinesin motor proteins such as KIF5A are known to be defective in some inherited neurodegenerative diseases.
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Affiliation(s)
- Junjun Zhao
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Albert Hiu Ka Fok
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Ruolin Fan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Pui-Yi Kwan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Hei-Lok Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Louisa Hoi-Ying Lo
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Ying-Shing Chan
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
| | - Wing-Ho Yung
- School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong, China
| | - Jiandong Huang
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China.,Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Cora Sau Wan Lai
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
| | - Kwok-On Lai
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China.,State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
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14
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Morrissey JA, Bigus E, Necarsulmer JC, Srinivasan V, Peppercorn K, O'Leary DJ, Mockett BG, Tate WP, Hughes SM, Parfitt KD, Abraham WC. The Tripeptide RER Mimics Secreted Amyloid Precursor Protein-Alpha in Upregulating LTP. Front Cell Neurosci 2019; 13:459. [PMID: 31680870 PMCID: PMC6813913 DOI: 10.3389/fncel.2019.00459] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/26/2019] [Indexed: 12/15/2022] Open
Abstract
Secreted amyloid precursor protein-alpha (sAPPα), generated by enzymatic processing of the APP, possesses a range of neurotrophic and neuroprotective properties and plays a critical role in the molecular mechanisms of memory and learning. One of the key active regions of sAPPα is the central APP domain (E2) that contains within it the tripeptide sequence, RER. This sequence is exposed on the surface of a coiled coil substructure of E2. RER has by itself displayed memory-enhancing properties, and can protect newly formed engrams from interference in a manner similar to that displayed by sAPPα itself. In order to determine whether RER mimics other properties of sAPPα, we investigated the electrophysiological effects of the N-terminal protected acetylated RER (Ac-RER) and an isoform containing a chiral switch in the first amino acid from an l- to a d-orientation (Ac-rER), on synaptic plasticity. We found that, like sAPPα, exogenous perfusion with nanomolar concentrations of Ac-RER or Ac-rER enhanced the induction and stability of long-term potentiation (LTP) in area CA1 of rat and mouse hippocampal slices, in a protein synthesis- and trafficking-dependent manner. This effect did not occur with a control Ac-AAA or Ac-IFR tripeptide, nor with a full-length sAPPα protein where RER was substituted with AAA. Ac-rER also protected LTP against amyloid-beta (Aβ25–35)-induced LTP impairment. Our findings provide further evidence that the RER-containing region of sAPPα is functionally significant and by itself can produce effects similar to those displayed by full length sAPPα, suggesting that this tripeptide, like sAPPα, may have therapeutic potential.
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Affiliation(s)
- Jodi A Morrissey
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand.,Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Erin Bigus
- Department of Neuroscience, Pomona College, Claremont, CA, United States
| | | | - Vinay Srinivasan
- Department of Neuroscience, Pomona College, Claremont, CA, United States
| | - Katie Peppercorn
- Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Daniel J O'Leary
- Department of Neuroscience, Pomona College, Claremont, CA, United States
| | - Bruce G Mockett
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Warren P Tate
- Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Stephanie M Hughes
- Department of Biochemistry, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Karen D Parfitt
- Department of Neuroscience, Pomona College, Claremont, CA, United States
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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15
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Glutamate Receptor Trafficking and Protein Synthesis Mediate the Facilitation of LTP by Secreted Amyloid Precursor Protein-Alpha. J Neurosci 2019; 39:3188-3203. [PMID: 30804097 DOI: 10.1523/jneurosci.1826-18.2019] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 01/15/2019] [Accepted: 02/11/2019] [Indexed: 01/08/2023] Open
Abstract
Secreted amyloid precursor protein-alpha (sAPPα) has growth factor-like properties and can modulate long-term potentiation (LTP) and memory. Here, we demonstrate that exposure to sAPPα converts short-lasting LTP into protein-synthesis-dependent late LTP in hippocampal slices from male rats. sAPPβ had no discernable effect. We hypothesized that sAPPα facilitated LTP via regulated glutamate receptor trafficking and de novo protein synthesis. We found using a linear mixed model that sAPPα stimulated trafficking of GluA2-lacking AMPARs, as well as NMDARs to the extrasynaptic cell surface, in a calcium/calmodulin-dependent kinase II and protein kinase G-dependent manner. Both cell surface receptor accumulation and LTP facilitation were present even after sAPPα washout and inhibition of receptor trafficking or protein synthesis prevented all these effects. Direct visualization of newly synthesized proteins (FUNCAT-PLA) confirmed the ability of sAPPα to stimulate de novo protein synthesis and revealed GluA1 as one of the upregulated proteins. Therefore, sAPPα generates a coordinated synthesis and trafficking of glutamate receptors to the cell surface that facilitate LTP.SIGNIFICANCE STATEMENT Secreted amyloid precursor protein-alpha (sAPPα) is a neurotrophic and neuroprotective protein that can promote synaptic plasticity and memory, yet the molecular mechanisms underlying these effects are still not well understood. Here, we show that sAPPα facilitates long-term potentiation (LTP) in a concentration-dependent fashion through cellular processes involving de novo protein synthesis and trafficking of both GluA2-lacking AMPARs and NMDARs to the extrasynaptic cell surface. sAPPα also enhances GluA1, but not GluA2, synthesis. The trafficking effects, along with the LTP facilitation, persist after sAPPα washout, revealing a metaplastic capability of exogenous sAPPα administration. sAPPα thus facilitates LTP through coordinated activation of protein synthesis and trafficking of glutamate receptors to the cell surface, where they are positioned for priming LTP.
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16
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Ryan B, Logan BJ, Abraham WC, Williams JM. MicroRNAs, miR-23a-3p and miR-151-3p, Are Regulated in Dentate Gyrus Neuropil following Induction of Long-Term Potentiation In Vivo. PLoS One 2017; 12:e0170407. [PMID: 28125614 PMCID: PMC5268419 DOI: 10.1371/journal.pone.0170407] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/04/2017] [Indexed: 01/04/2023] Open
Abstract
Translation of synaptic mRNA contributes to alterations in the proteome necessary to consolidate long-term potentiation (LTP), a model of memory processes. Yet, how this process is controlled is not fully resolved. MicroRNAs are non-coding RNAs that negatively regulate gene expression by suppressing translation or promoting mRNA degradation. As specific microRNAs are synaptically located, we hypothesized that they are ideally suited to couple synaptic activation, translational regulation, and LTP persistence. The aim of this study was to identify LTP-regulated microRNAs at or near synapses. Accordingly, LTP was induced unilaterally at perforant path-dentate gyrus synapses in awake adult Sprague-Dawley rats. Five hours later, dentate gyrus middle molecular layer neuropil, containing potentiated synapses, was laser-microdissected. MicroRNA expression profiling, using TaqMan Low Density MicroRNA Microarrays (n = 4), identified eight regulated microRNAs. Subsequent individual TaqMan assays confirmed upregulation of miR-23a-3p (1.30 ± 0.10; p = 0.015) and miR-151-3p (1.17 ± 0.19; p = 0.045) in a second cohort (n = 7). Interestingly, bioinformatic analysis indicated that miR-151-3p and miR-23a-3p regulate synaptic reorganisation and transcription, respectively. In summary, we have demonstrated for the first time that microRNAs are regulated in isolated neuropil following LTP induction in vivo, supporting the hypothesis that synaptic, LTP-responsive microRNAs contribute to LTP persistence via regulation of the synaptic proteome.
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Affiliation(s)
- Brigid Ryan
- Department of Anatomy, University of Otago, Dunedin, New Zealand
- The Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Brain Research New Zealand, Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
| | - Barbara J. Logan
- The Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Brain Research New Zealand, Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Wickliffe C. Abraham
- The Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Brain Research New Zealand, Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Joanna M. Williams
- Department of Anatomy, University of Otago, Dunedin, New Zealand
- The Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Brain Research New Zealand, Rangahau Roro Aotearoa, University of Otago, Dunedin, New Zealand
- * E-mail:
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17
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Caudal D, Rame M, Jay TM, Godsil BP. Dynamic Regulation of AMPAR Phosphorylation In Vivo Following Acute Behavioral Stress. Cell Mol Neurobiol 2016; 36:1331-1342. [PMID: 26814839 DOI: 10.1007/s10571-016-0332-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 07/31/2015] [Indexed: 12/20/2022]
Abstract
The tuning of glutamatergic transmission is an essential mechanism for neuronal communication. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are ionotropic glutamate receptors that mediate fast synaptic transmission. The phosphorylation states of specific serine residues on the GluA1 and GluA2 AMPAR subunits are considered critical post-translational modifications that regulate AMPAR activity and subcellular trafficking. While behavioral stress, via stress hormones, exerts specific alterations on such glutamatergic processes, there have been conflicting data concerning the influence of stress on AMPAR phosphorylation in different brain regions, and the post-stress signaling mechanisms mediating these processes are not well delineated. Here, we examined the dynamics of phosphorylation at three AMPAR serine residues (ser831-GluA1, ser845-GluA1, and ser880-GluA2) in four brain regions [amygdala, medial prefrontal cortex (mPFC), dorsal hippocampus, and ventral hippocampus] of the rat during the hour following behavioral stress. We also tested the impact of post-stress corticosteroid receptor blockade on AMPAR phosphorylation. Both GluA1 subunit residues exhibited elevated phosphorylation after stress, yet post-stress administration of corticosteroid receptor antagonists curtailed these effects only at ser831-GluA1. In contrast, ser880-GluA2 displayed a time-dependent tendency for early decreased phosphorylation (that was selectively augmented by mifepristone treatment in the amygdala and mPFC of stressed animals) followed by increased phosphorylation later on. These findings show that the in vivo regulation of AMPAR phosphorylation after stress is a dynamic and subunit-specific process, and they provide support for the hypothesis that corticosteroid receptors have an ongoing role in the regulation of ser831-GluA1 phosphorylation during the post-stress interval.
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Affiliation(s)
- Dorian Caudal
- Physiopathologie des Maladies Psychiatriques, UMR_S 894 Inserm, Centre de Psychiatrie et Neurosciences, 2ter rue d'Alesia, 75014, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Marion Rame
- Physiopathologie des Maladies Psychiatriques, UMR_S 894 Inserm, Centre de Psychiatrie et Neurosciences, 2ter rue d'Alesia, 75014, Paris, France
| | - Thérèse M Jay
- Physiopathologie des Maladies Psychiatriques, UMR_S 894 Inserm, Centre de Psychiatrie et Neurosciences, 2ter rue d'Alesia, 75014, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Bill P Godsil
- Physiopathologie des Maladies Psychiatriques, UMR_S 894 Inserm, Centre de Psychiatrie et Neurosciences, 2ter rue d'Alesia, 75014, Paris, France.
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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18
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Novel microRNA revealed by systematic analysis of the microRNA transcriptome in dentate gyrus granule cells. Neurosci Lett 2016; 707:132280. [PMID: 27612590 DOI: 10.1016/j.neulet.2016.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/22/2016] [Accepted: 09/02/2016] [Indexed: 12/17/2022]
Abstract
Post-transcriptional control of gene expression by microRNAs provides an important regulatory system within neurons, allowing co-ordinate and fine-tuned expression of plasticity-related proteins. Indeed, specific microRNAs have been shown to be regulated by synaptic activity in the dentate gyrus, and contribute to the regulated gene expression that underlies the persistence of long-term potentiation (LTP), a model of memory. To fully explore the contribution of microRNAs in synaptic plasticity, it is important to characterize the complete microRNA transcriptome in regions such as the dentate gyrus. Accordingly we used deep sequencing and miRDeep* analysis to search for novel microRNAs expressed in the dentate gyrus granule cell layer. Drawing on combined sequencing and bioinformatics analyses, including hairpin stability and patterns of precursor microRNA processing, we identified nine putative novel microRNAs. We did not find evidence of differential expression of any of these putative microRNAs following LTP at perforant path-granule cell synapses in awake rats (5 h post-tetanus; p > 0.05). Focusing on novel_miR-1, the most abundant novel miRNA, we showed that this sequence could be amplified from RNA extracted from dentate gyrus granule cells by reverse transcription-quantitative polymerase chain reaction. Further, by computationally predicting mRNA targets of this microRNA, we found that this novel microRNA likely contributes to the regulation of proteins that function at synapses.
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19
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Maity S, Rah S, Sonenberg N, Gkogkas CG, Nguyen PV. Norepinephrine triggers metaplasticity of LTP by increasing translation of specific mRNAs. ACTA ACUST UNITED AC 2015; 22:499-508. [PMID: 26373828 PMCID: PMC4579357 DOI: 10.1101/lm.039222.115] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 06/30/2015] [Indexed: 12/24/2022]
Abstract
Norepinephrine (NE) is a key modulator of synaptic plasticity in the hippocampus, a brain structure crucially involved in memory formation. NE boosts synaptic plasticity mostly through initiation of signaling cascades downstream from beta (β)-adrenergic receptors (β-ARs). Previous studies demonstrated that a β-adrenergic receptor agonist, isoproterenol, can modify the threshold for long-term potentiation (LTP), a putative cellular mechanism for learning and memory, in a process known as “metaplasticity.” Metaplasticity is the ability of synaptic plasticity to be modified by prior experience. We asked whether NE itself could engage metaplastic mechanisms in area CA1 of mouse hippocampal slices. Using extracellular field potential recording and stimulation, we show that application of NE (10 µM), which did not alter basal synaptic strength, enhances the future maintenance of LTP elicited by subthreshold, high-frequency stimulation (HFS: 1 × 100 Hz, 1 sec). HFS applied 30 min after NE washout induced long-lasting (>4 h) LTP, which was significantly extended in duration relative to HFS alone. This NE-induced metaplasticity required β1-AR activation, as coapplication of the β1-receptor antagonist CGP-20712A (1 µM) attenuated maintenance of LTP. We also found that NE-mediated metaplasticity was translation- and transcription-dependent. Polysomal profiles of CA1 revealed increased translation rates for specific mRNAs during NE-induced metaplasticity. Thus, activation of β-ARs by NE primes synapses for future long-lasting plasticity on time scales extending beyond fast synaptic transmission; this may facilitate neural information processing and the subsequent formation of lasting memories.
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Affiliation(s)
- Sabyasachi Maity
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
| | - Sean Rah
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
| | - Nahum Sonenberg
- Department of Biochemistry, Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Christos G Gkogkas
- Patrick Wild Centre and Centre for Integrative Biology, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Peter V Nguyen
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Department of Psychiatry, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada Neuroscience and Mental Health Institute, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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20
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Ryan B, Joilin G, Williams JM. Plasticity-related microRNA and their potential contribution to the maintenance of long-term potentiation. Front Mol Neurosci 2015; 8:4. [PMID: 25755632 PMCID: PMC4337328 DOI: 10.3389/fnmol.2015.00004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/04/2015] [Indexed: 12/24/2022] Open
Abstract
Long-term potentiation (LTP) is a form of synaptic plasticity that is an excellent model for the molecular mechanisms that underlie memory. LTP, like memory, is persistent, and both are widely believed to be maintained by a coordinated genomic response. Recently, a novel class of non-coding RNA, microRNA, has been implicated in the regulation of LTP. MicroRNA negatively regulate protein synthesis by binding to specific messenger RNA response elements. The aim of this review is to summarize experimental evidence for the proposal that microRNA play a major role in the regulation of LTP. We discuss a growing body of research which indicates that specific microRNA regulate synaptic proteins relevant to LTP maintenance, as well as studies that have reported differential expression of microRNA in response to LTP induction. We conclude that microRNA are ideally suited to contribute to the regulation of LTP-related gene expression; microRNA are pleiotropic, synaptically located, tightly regulated, and function in response to synaptic activity. The potential impact of microRNA on LTP maintenance as regulators of gene expression is enormous.
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Affiliation(s)
- Brigid Ryan
- Brain Health Research Centre, University of Otago, Dunedin New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin New Zealand
| | - Greig Joilin
- Brain Health Research Centre, University of Otago, Dunedin New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin New Zealand
| | - Joanna M Williams
- Brain Health Research Centre, University of Otago, Dunedin New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago, Dunedin New Zealand
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21
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Chen LJ, Wang YJ, Chen JR, Tseng GF. NMDA receptor triggered molecular cascade underlies compression-induced rapid dendritic spine plasticity in cortical neurons. Exp Neurol 2015; 266:86-98. [PMID: 25708984 DOI: 10.1016/j.expneurol.2015.02.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 12/05/2014] [Accepted: 02/09/2015] [Indexed: 10/24/2022]
Abstract
Compression causes the reduction of dendritic spines of underlying adult cortical pyramidal neurons but the mechanisms remain at large. Using a rat epidural cerebral compression model, dendritic spines on the more superficial-lying layer III pyramidal neurons were found quickly reduced in 12h, while those on the deep-located layer V pyramidal neurons were reduced slightly later, starting 1day following compression. No change in the synaptic vesicle markers synaptophysin and vesicular glutamate transporter 1 suggest no change in afferents. Postsynaptically, N-methyl-d-aspartate (NMDA) receptor trafficking to synaptic membrane was detected in 10min and lasting to 1day after compression. Translocation of calcineurin to synapses and enhancement of its enzymatic activity were detected within 10min as well. These suggest that compression rapidly activated NMDA receptors to increase postsynaptic calcium, which then activated the phosphatase calcineurin. In line with this, dephosphorylation and activation of the actin severing protein cofilin, and the consequent depolymerization of actin were all identified in the compressed cortex within matching time frames. Antagonizing NMDA receptors with MK801 before compression prevented this cascade of events, including NR1 mobilization, calcineurin activation and actin depolymerization, in the affected cortex. Morphologically, MK801 pretreatment prevented the loss of dendritic spines on the compressed cortical pyramidal neurons as well. In short, we demonstrated, for the first time, mechanisms underlying the rapid compression-induced cortical neuronal dendritic spine plasticity. In addition, the mechanical force of compression appears to activate NMDA receptors to initiate a rapid postsynaptic molecular cascade to trim dendritic spines on the compressed cortical pyramidal neurons within half a day.
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Affiliation(s)
- Li-Jin Chen
- Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien, Taiwan
| | - Yueh-Jan Wang
- Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien, Taiwan
| | - Jeng-Rung Chen
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung-Hsing University, Taichung, Taiwan
| | - Guo-Fang Tseng
- Department of Anatomy, College of Medicine, Tzu-Chi University, Hualien, Taiwan.
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22
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Ryan MM, Guévremont D, Luxmanan C, Abraham WC, Williams JM. Aging alters long-term potentiation--related gene networks and impairs synaptic protein synthesis in the rat hippocampus. Neurobiol Aging 2015; 36:1868-80. [PMID: 25716081 DOI: 10.1016/j.neurobiolaging.2015.01.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 01/12/2015] [Accepted: 01/14/2015] [Indexed: 10/24/2022]
Abstract
During aging, memory retention and persistence of long-term potentiation (LTP) are impaired, suggesting an aging-related deterioration in mechanisms regulating information storage. Late-phase LTP requires synthesis of proteins at synapses as well as integrated regulation of gene networks. Because aging diminishes the persistence of LTP, primarily by affecting the transition between early and late phases, we assessed whether this was reflected in perturbation of gene networks. Using DNA microarray analysis, we compared LTP-associated gene expression in young (5 months), middle-aged (15 months), and old (22 months) male Sprague-Dawley rats. As expected, we found no significant difference in LTP measured 20 minutes postinduction; however, we found that overall more genes were regulated in the young group. Bioinformatics predicted not only dysregulation of activator protein-1 and nuclear factor kB transcription factor activity and epigenetic modifications but also dysregulation of protein synthesis. Notably, we confirmed an age-related impairment in metabotropic and ionotropic receptor-mediated synaptic protein synthesis. Together, these results demonstrate that LTP-specific gene expression is altered with aging and suggest that dysregulation of synaptic protein synthesis also contributes to the age-dependent reduction in LTP persistence.
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Affiliation(s)
- Margaret M Ryan
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Diane Guévremont
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Carthika Luxmanan
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand
| | - Wickliffe C Abraham
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand; Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Joanna M Williams
- Department of Anatomy, University of Otago, Dunedin, New Zealand; Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
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23
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Joilin G, Guévremont D, Ryan B, Claudianos C, Cristino AS, Abraham WC, Williams JM. Rapid regulation of microRNA following induction of long-term potentiation in vivo. Front Mol Neurosci 2014; 7:98. [PMID: 25538559 PMCID: PMC4260481 DOI: 10.3389/fnmol.2014.00098] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 11/24/2014] [Indexed: 01/09/2023] Open
Abstract
Coordinated regulation of gene expression is essential for consolidation of the memory mechanism, long-term potentiation (LTP). Triggering of LTP by N-methyl-D-aspartate receptor (NMDAR) activation rapidly activates constitutive and inducible transcription factors, which promote expression of genes responsible for LTP maintenance. As microRNA (miRNA) coordinate expression of genes related through seed sites, we hypothesize that miRNA contribute to the regulation of the LTP-induced gene response. MiRNA function primarily as negative regulators of gene expression. As LTP induction promotes a generalized rapid up-regulation of gene expression, we predicted a complementary rapid down-regulation of miRNA levels. Accordingly, we carried out global miRNA expression profiling in the rat dentate gyrus 20 min post-LTP induction in vivo. Consistent with our hypothesis, we found a large number of differentially expressed miRNA, the majority down-regulated. Detailed analysis of miR-34a-5p and miR-132-3p revealed this down-regulation was transient and NMDAR-dependent, whereby block of NMDARs released an activity-associated inhibitory mechanism. Furthermore, down-regulation of mature miR-34a-5p and miR-132-3p occurred solely by post-transcriptional mechanisms, occurring despite an associated up-regulation of the pri-miR-132 transcript. To understand how down-regulation of miR-34a-5p and miR-132-3p intersects with the molecular events occurring following LTP, we used bioinformatics to identify potential targets. Previously validated targets included the key LTP-regulated genes Arc and glutamate receptor subunits. Predicted targets included the LTP-linked kinase, Mapk1, and neuropil-associated transcripts Hn1 and Klhl11, which were validated using luciferase reporter assays. Furthermore, we found that the level of p42-Mapk1, the protein encoded by the Mapk1 transcript, was up-regulated following LTP. Together, these data support the interpretation that miRNA, in particular miR-34a-5p and miR-132-3p, make a surprisingly rapid contribution to synaptic plasticity via dis-inhibition of translation of key plasticity-related molecules.
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Affiliation(s)
- Greig Joilin
- Brain Health Research Centre, University of Otago Dunedin, New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Diane Guévremont
- Brain Health Research Centre, University of Otago Dunedin, New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Brigid Ryan
- Brain Health Research Centre, University of Otago Dunedin, New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Charles Claudianos
- Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia
| | - Alexandre S Cristino
- Queensland Brain Institute, The University of Queensland Brisbane, QLD, Australia
| | - Wickliffe C Abraham
- Brain Health Research Centre, University of Otago Dunedin, New Zealand ; Department of Psychology, University of Otago Dunedin, New Zealand
| | - Joanna M Williams
- Brain Health Research Centre, University of Otago Dunedin, New Zealand ; Department of Anatomy, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
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Association of aberrant neural synchrony and altered GAD67 expression following exposure to maternal immune activation, a risk factor for schizophrenia. Transl Psychiatry 2014; 4:e418. [PMID: 25072323 PMCID: PMC4119228 DOI: 10.1038/tp.2014.64] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 06/15/2014] [Accepted: 06/16/2014] [Indexed: 12/31/2022] Open
Abstract
A failure of integrative processes within the brain, mediated via altered GABAergic inhibition, may underlie several features of schizophrenia. The present study examined, therefore, whether maternal immune activation (MIA), a risk factor for schizophrenia, altered inhibitory markers in the hippocampus and medial prefrontal cortex (mPFC), while also altering electroencephalogram (EEG) coherence between these regions. Pregnant rats were treated with saline or polyinosinic:polycytidylic acid mid-gestation. EEG depth recordings were made from the dorsal and ventral hippocampus and mPFC of male adult offspring. Glutamic decarboxylase (GAD67) levels were separately assayed in these regions using western blot. GAD67 expression was also assessed within parvalbumin-positive cells in the dorsal and ventral hippocampus using immunofluorescence alongside stereological analysis of parvalbumin-positive cell numbers. EEG coherence was reduced between the dorsal hippocampus and mPFC, but not the ventral hippocampus and mPFC, in MIA animals. Western blot and immunofluorescence analyses revealed that GAD67 expression within parvalbumin-positive cells was also reduced in the dorsal hippocampus relative to ventral hippocampus in MIA animals when compared with controls. This reduction was observed in the absence of parvalbumin-positive neuronal loss. Overall, MIA produced a selective reduction in EEG coherence between the dorsal hippocampus and mPFC that was paralleled by a similarly specific reduction in GAD67 within parvalbumin-positive cells of the dorsal hippocampus. These results suggest a link between altered inhibitory mechanisms and synchrony and, therefore point to potential mechanisms via which a disruption in neurodevelopmental processes might lead to pathophysiology associated with schizophrenia.
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Weiss S, Mori F, Rossi S, Centonze D. Disability in multiple sclerosis: When synaptic long-term potentiation fails. Neurosci Biobehav Rev 2014; 43:88-99. [DOI: 10.1016/j.neubiorev.2014.03.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/11/2014] [Accepted: 03/31/2014] [Indexed: 12/13/2022]
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Redistribution of ionotropic glutamate receptors detected by laser microdissection of the rat dentate gyrus 48 h following LTP induction in vivo. PLoS One 2014; 9:e92972. [PMID: 24667777 PMCID: PMC3965487 DOI: 10.1371/journal.pone.0092972] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 02/27/2014] [Indexed: 11/25/2022] Open
Abstract
The persistence and input specificity of long-term potentiation (LTP) make it attractive as a mechanism of information storage. In its initial phase, both in vivo and in vitro studies have shown that LTP is associated with increased membrane localization of AMPA receptor subunits, but the molecular basis of LTP maintenance over the long-term is still unclear. We have previously shown that expression of AMPA and NMDA receptor subunits is elevated in whole homogenates prepared from dentate gyrus 48 h after LTP induction in vivo. In the present study, we utilized laser microdissection (LMD) techniques to determine whether AMPA and NMDA receptor upregulation occurs specifically in the stimulated regions of the dentate gyrus dendritic arbor. Receptor proteins GluN1, GluA1 and GluA2, as well as postsynaptic density protein of 95 kDa and tubulin were detected by Western blot analysis in microdissected samples. Gradients of expression were observed for GluN1 and GluA2, decreasing from the inner to the outer zones of the molecular layer, and were independent of LTP. When induced at medial perforant path synapses, LTP was associated with an apparent specific redistribution of GluA1 and GluN1 to the middle molecular layer that contains these synapses. These data indicate that glutamate receptor proteins are delivered specifically to dendritic regions possessing LTP-expressing synapses, and that these changes are preserved for at least 48 h.
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Trotman M, Barad Z, Guévremont D, Williams J, Leitch B. Changes in the GRIP 1&2 scaffolding proteins in the cerebellum of the ataxic stargazer mouse. Brain Res 2013; 1546:53-62. [PMID: 24380676 DOI: 10.1016/j.brainres.2013.12.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 12/20/2013] [Indexed: 10/25/2022]
Abstract
Glutamate receptor-interacting proteins (GRIP1&2) and protein-interacting with C kinase-1 (PICK1) are synaptic scaffold proteins associated with the stabilization and recycling of synaptic GluA2-, 3- and 4c-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). PICK1-mediated phosphorylation of GluA serine880 uncouples GRIP1&2 leading to AMPAR endocytosis, important in mediating forms of synaptic plasticity underlying learning and memory. Ataxic and epileptic stargazer mice possess a mutation in the CACNG2 gene encoding the transmembrane AMPAR-regulatory protein (TARP)-γ2 (stargazin). TARPs are AMPAR-auxiliary subunits required for efficient AMPAR trafficking to synapses. Stargazin is abundantly expressed in the cerebellum and its loss results in severe deficits in AMPAR trafficking to cerebellar synapses, particularly at granule cell (GC) synapses, leading to the ataxic phenotype of stargazers. However, how the stargazin mutation impacts on the expression of other AMPAR-interacting scaffold proteins is unknown. This study shows a significant increase in GRIP1&2, but not PICK1, levels in whole tissue and synapse-enriched extracts from stargazer cerebella. Post-embedding immunogold-cytochemistry electron microscopy showed GRIP1&2 levels were unchanged at mossy fiber-GC synapses in stargazers, which are silent due to virtual total absence of synaptic and extrasynaptic GluA2/3-AMPARs. These results indicate that loss of synaptic AMPARs at this excitatory synapse does not affect GRIP1&2 expression within the postsynaptic region of mossy fiber-GC synapses. Interestingly, increased GRIP and reduced GluA2-AMPARexpression also occur in cerebella of autistic patients. Further research establishing the role of elevated cerebellar GRIP1&2 in stargazers may help identify common cellular mechanisms in the comorbid disorders ataxia, epilepsy and autism leading to more effective treatment strategies.
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Affiliation(s)
- M Trotman
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - Z Barad
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - D Guévremont
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - J Williams
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
| | - B Leitch
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
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Paradox effects of kynurenines on LTP induction in the Wistar rat. An in vivo study. Neurosci Lett 2013; 553:138-41. [PMID: 23978510 DOI: 10.1016/j.neulet.2013.08.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 08/05/2013] [Accepted: 08/14/2013] [Indexed: 11/20/2022]
Abstract
Kynurenic acid (KYNA), a neuroactive metabolite of tryptophan that acts on different receptors (e.g. those of N-methyl-D-aspartate (NMDA) and presynaptic α7 nicotinic acetylcholine (nACh)), exerts fundamentally antiglutamatergic effects. In view of its antiglutamatergic properties, an elevation of the KYNA level within the brain might result in neuroprotection. However, the use of KYNA as a neuroprotective agent is rather limited, because it crosses the blood-brain barrier (BBB) to only a poor extent. During recent years, new KYNA derivatives have been developed which can readily traverse the BBB and also exert neuroprotection. However, as KYNA and its derivatives are able to interfere with glutamatergic and cholinergic transmission, the potential risks of interfering with cognitive functions cannot be excluded. This in vivo study on anesthetized rats therefore tested the effects of the administration of KYNA and a KYNA derivative (SZR72) (in a dosage that exerted neuroprotection) on long-term potentiation (LTP) and pure field excitatory postsynaptic potentials induced by contralateral CA3 region stimulation and recorded in the pyramidal layer of the CA1 region of the hippocampus. Surprisingly, KYNA and this derivative did not reduce, but rather increased the induceability of LTP. The possible explanation is discussed in detail. In brief: an elevated KYNA level in the perisynaptic area produced, for example, by exogenous prodrug or derivative administration exerts preferential effects on the extrasynaptic NMDA receptors and the nACh receptors on presynaptic glutamatergic terminals, while sparing the currents mediated by synaptic NMDA and α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptors. This might be the explanation why the treatment with the prodrug of KYNA or the KYNA derivative in a dosage which induced neuroprotection did not reduce the cognitive functions or the LTP.
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Eckert MJ, Guévremont D, Williams JM, Abraham WC. Rapid visual stimulation increases extrasynaptic glutamate receptor expression but not visual-evoked potentials in the adult rat primary visual cortex. Eur J Neurosci 2013; 37:400-6. [PMID: 23373691 DOI: 10.1111/ejn.12053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 09/28/2012] [Accepted: 10/10/2012] [Indexed: 11/29/2022]
Abstract
The model most used to study synaptic plasticity, long-term potentiation (LTP), typically employs electrical stimulation of afferent fibers to induce changes in synaptic strength. It would be beneficial for understanding the behavioral relevance of LTP if a model could be developed that used more naturalistic stimuli. Recent evidence suggests that the adult visual cortex, previously thought to have lost most of its plasticity once past the critical period, is in fact capable of LTP-like changes in synaptic strength in response to sensory manipulations alone. In a preliminary study, we used a photic tetanus (PT; flashing checkerboard stimulus) to induce an enhancement of the visual-evoked potential (VEP) in the primary visual cortex of anesthetised adult rats. In the present study, we sought to compare the mechanisms of this novel sensory LTP with those of traditional electrical LTP. Unexpectedly, we found that sensory LTP was not induced as reliably as we had observed previously, as manipulations of several parameters failed to lead to significant potentiation of the VEP. However, we did observe a significant increase in visual cortex glutamate receptor expression on the surface of isolated synapses following the PT. Both AMPA receptor expression and N-methyl-d-aspartate (NMDA) receptor subunit expression were increased, specifically in extrasynaptic regions of the membrane, in PT animals. These results provide biochemical confirmation of the lack of change in the VEP in response to PT, but suggest that PT may prime synapses for strengthening upon appropriate subsequent activation, through the trafficking of glutamate receptors to the cell surface.
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Affiliation(s)
- M J Eckert
- Department of Psychology, Brain Health Research Centre, University of Otago, Dunedin, New Zealand.
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Henderson C, Wijetunge L, Kinoshita MN, Shumway M, Hammond RS, Postma FR, Brynczka C, Rush R, Thomas A, Paylor R, Warren ST, Vanderklish PW, Kind PC, Carpenter RL, Bear MF, Healy AM. Reversal of disease-related pathologies in the fragile X mouse model by selective activation of GABAB receptors with arbaclofen. Sci Transl Med 2013; 4:152ra128. [PMID: 22993295 DOI: 10.1126/scitranslmed.3004218] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Fragile X syndrome (FXS), the most common inherited cause of intellectual disability and autism, results from the transcriptional silencing of FMR1 and loss of the mRNA translational repressor protein fragile X mental retardation protein (FMRP). Patients with FXS exhibit changes in neuronal dendritic spine morphology, a pathology associated with altered synaptic function. Studies in the mouse model of fragile X have shown that loss of FMRP causes excessive synaptic protein synthesis, which results in synaptic dysfunction and altered spine morphology. We tested whether the pharmacologic activation of the γ-aminobutyric acid type B (GABA(B)) receptor could correct or reverse these phenotypes in Fmr1-knockout mice. Basal protein synthesis, which is elevated in the hippocampus of Fmr1-knockout mice, was corrected by the in vitro application of the selective GABA(B) receptor agonist STX209 (arbaclofen, R-baclofen). STX209 also reduced to wild-type values the elevated AMPA receptor internalization in Fmr1-knockout cultured neurons, a known functional consequence of increased protein synthesis. Acute administration of STX209 in vivo, at doses that modify behavior, decreased mRNA translation in the cortex of Fmr1-knockout mice. Finally, the chronic administration of STX209 in juvenile mice corrected the increased spine density in Fmr1-knockout mice without affecting spine density in wild-type mice. Thus, activation of the GABA(B) receptor with STX209 corrected synaptic abnormalities considered central to fragile X pathophysiology, a finding that suggests that STX209 may be a potentially effective therapy to treat the core symptoms of FXS.
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Cox DJ, Racca C. Differential dendritic targeting of AMPA receptor subunit mRNAs in adult rat hippocampal principal neurons and interneurons. J Comp Neurol 2013; 521:1954-2007. [DOI: 10.1002/cne.23292] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
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GluA1 and its PDZ-interaction: a role in experience-dependent behavioral plasticity in the forced swim test. Neurobiol Dis 2012; 52:160-7. [PMID: 23262314 DOI: 10.1016/j.nbd.2012.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 12/05/2012] [Accepted: 12/08/2012] [Indexed: 01/10/2023] Open
Abstract
Glutamate receptor dependent synaptic plasticity plays an important role in the pathophysiology of depression. Hippocampal samples from clinically depressed patients display reduced mRNA levels for GluA1, a major subunit of AMPA receptors. Moreover, activation and synaptic incorporation of GluA1-containing AMPA receptors are required for the antidepressant-like effects of NMDA receptor antagonists. These findings argue that GluA1-dependent synaptic plasticity might be critically involved in the expression of depression. Using an animal model of depression, we demonstrate that global or hippocampus-selective deletion of GluA1 impairs expression of experience-dependent behavioral despair. This impairment is mediated by the interaction of GluA1 with PDZ-binding domain proteins, as deletion of the C-terminal leucine alone is sufficient to replicate the behavioral phenotype. Our results provide evidence for a significant role of hippocampal GluA1-containing AMPA receptors and their PDZ-interaction in experience-dependent expression of behavioral despair and link mechanisms of hippocampal synaptic plasticity with behavioral expression of depression.
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Ryan MM, Ryan B, Kyrke-Smith M, Logan B, Tate WP, Abraham WC, Williams JM. Temporal profiling of gene networks associated with the late phase of long-term potentiation in vivo. PLoS One 2012; 7:e40538. [PMID: 22802965 PMCID: PMC3393663 DOI: 10.1371/journal.pone.0040538] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 06/08/2012] [Indexed: 01/02/2023] Open
Abstract
Long-term potentiation (LTP) is widely accepted as a cellular mechanism underlying memory processes. It is well established that LTP persistence is strongly dependent on activation of constitutive and inducible transcription factors, but there is limited information regarding the downstream gene networks and controlling elements that coalesce to stabilise LTP. To identify these gene networks, we used Affymetrix RAT230.2 microarrays to detect genes regulated 5 h and 24 h (n = 5) after LTP induction at perforant path synapses in the dentate gyrus of awake adult rats. The functional relationships of the differentially expressed genes were examined using DAVID and Ingenuity Pathway Analysis, and compared with our previous data derived 20 min post-LTP induction in vivo. This analysis showed that LTP-related genes are predominantly upregulated at 5 h but that there is pronounced downregulation of gene expression at 24 h after LTP induction. Analysis of the structure of the networks and canonical pathways predicted a regulation of calcium dynamics via G-protein coupled receptors, dendritogenesis and neurogenesis at the 5 h time-point. By 24 h neurotrophin-NFKB driven pathways of neuronal growth were identified. The temporal shift in gene expression appears to be mediated by regulation of protein synthesis, ubiquitination and time-dependent regulation of specific microRNA and histone deacetylase expression. Together this programme of genomic responses, marked by both homeostatic and growth pathways, is likely to be critical for the consolidation of LTP in vivo.
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Affiliation(s)
- Margaret M. Ryan
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Anatomy, Otago School of Medical Sciences, Dunedin, New Zealand
- Department of Biochemistry, Otago School of Medical Sciences, Dunedin, New Zealand
| | - Brigid Ryan
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Anatomy, Otago School of Medical Sciences, Dunedin, New Zealand
| | - Madeleine Kyrke-Smith
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Anatomy, Otago School of Medical Sciences, Dunedin, New Zealand
| | - Barbara Logan
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Warren P. Tate
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Biochemistry, Otago School of Medical Sciences, Dunedin, New Zealand
| | - Wickliffe C. Abraham
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Psychology, University of Otago, Dunedin, New Zealand
| | - Joanna M. Williams
- Brain Health Research Centre, University of Otago, Dunedin, New Zealand
- Department of Anatomy, Otago School of Medical Sciences, Dunedin, New Zealand
- * E-mail:
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Li Y, Zhang X, Liu H, Cao Z, Chen S, Cao B, Liu J. Phosphorylated CaMKII post-synaptic binding to NR2B subunits in the anterior cingulate cortex mediates visceral pain in visceral hypersensitive rats. J Neurochem 2012; 121:662-71. [PMID: 22380661 DOI: 10.1111/j.1471-4159.2012.07717.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The NR2B subunit of NMDA receptor in the anterior cingulate cortex (ACC) is up-regulated in viscerally hypersensitive (VH) rats induced by colonic anaphylaxis. It plays a critical role in modulation of ACC sensitization and visceral pain responses. Given the key role of calcium/calmodulin-dependent protein kinase II (CaMKII) in synaptic plasticity and behavior learning and memory, we hypothesize that phosphorylation of CaMKII binding to NR2B mediates visceral pain in VH states. We performed in vivo electroporation of CaMKII siRNA produced inhibition of colorectal distension-induced visceromotor response in the VH rats. The NR2B, CaMKII and P-CaMKII-Thr²⁸⁶ protein levels were increased in 180%, 220% and 304% fold in the post-synaptic density (PSD) fraction in VH rats separately. Western blotting following co-immunoprecipitation showed that P-CaMKII-Thr²⁸⁶ bound to NR2B in the PSD, which was increased to 267% of control in VH rats. Administration of CaMKII antagonist Antennapedia-CaMKIINtide suppressed visceromotor response in VH rats in parallel with decrease of NR2B levels and reduction of the NR2B-P-CaMKII-Thr²⁸⁶ protein complex in PSD. In conclusion, CaMKII is a critical signaling molecule in the ACC glutamatergic synaptic transmission and phosphorylation of CaMKII at Thr286, which binds to NR2B subunit at post-synaptic site, modulates visceral pain in viscerally hypersensitive state.
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Affiliation(s)
- Ying Li
- Neuroscience Laboratory, Department of Biology and Chemistry, the City University of Hong Kong, Kowloon, Hong Kong.
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Christian DT, Alexander NJ, Diaz MR, Robinson S, McCool BA. Chronic intermittent ethanol and withdrawal differentially modulate basolateral amygdala AMPA-type glutamate receptor function and trafficking. Neuropharmacology 2012; 62:2430-9. [PMID: 22387532 DOI: 10.1016/j.neuropharm.2012.02.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/15/2012] [Accepted: 02/16/2012] [Indexed: 12/19/2022]
Abstract
The amygdala plays a critical role in the generation and expression of anxiety-like behaviors including those expressed following withdrawal (WD) from chronic intermittent ethanol (CIE) exposure. In particular, the BLA glutamatergic system controls the expression of both innate and pathological anxiety. Recent data suggests that CIE and WD may functionally alter this system in a manner that closely parallels memory-related phenomena like long-term potentiation (LTP). We therefore specifically dissected CIE/WD-induced changes in glutamatergic signaling using electrophysiological and biochemical approaches with a particular focus on the plasticity-related components of this neurotransmitter system. Our results indicate that cortical glutamatergic inputs arriving at BLA principal via the external capsule undergo predominantly post-synaptic alterations in AMPA receptor function following CIE and WD. Biochemical analysis revealed treatment-dependent changes in AMPA receptor surface expression and subunit phosphorylation that are complemented by changes in total protein levels and/or phosphorylation status of several key, plasticity-associated protein kinases such as calcium/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC). Together, these data show that CIE- and WD-induced changes in BLA glutamatergic function both functionally and biochemically mimic plasticity-related states. These mechanisms likely contribute to long-term increases in anxiety-like behavior following chronic ethanol exposure.
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Affiliation(s)
- Daniel T Christian
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Hunt DL, Castillo PE. Synaptic plasticity of NMDA receptors: mechanisms and functional implications. Curr Opin Neurobiol 2012; 22:496-508. [PMID: 22325859 DOI: 10.1016/j.conb.2012.01.007] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/09/2011] [Accepted: 01/19/2012] [Indexed: 12/11/2022]
Abstract
Beyond their well-established role as triggers for LTP and LTD of fast synaptic transmission mediated by AMPA receptors, an expanding body of evidence indicates that NMDA receptors (NMDARs) themselves are also dynamically regulated and subject to activity-dependent long-term plasticity. NMDARs can significantly contribute to information transfer at synapses particularly during periods of repetitive activity. It is also increasingly recognized that NMDARs participate in dendritic synaptic integration and are critical for generating persistent activity of neural assemblies. Here we review recent advances on the mechanisms and functional consequences of NMDAR plasticity. Given the unique biophysical properties of NMDARs, synaptic plasticity of NMDAR-mediated transmission emerges as a particularly powerful mechanism for the fine tuning of information encoding and storage throughout the brain.
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Affiliation(s)
- David L Hunt
- Dominick P. Purpura, Department of Neuroscience, Albert Einstein College of Medicine, Kennedy Center, Room 703, Bronx, NY 10461, United States
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Bourne JN, Harris KM. Coordination of size and number of excitatory and inhibitory synapses results in a balanced structural plasticity along mature hippocampal CA1 dendrites during LTP. Hippocampus 2011; 21:354-73. [PMID: 20101601 DOI: 10.1002/hipo.20768] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Enlargement of dendritic spines and synapses correlates with enhanced synaptic strength during long-term potentiation (LTP), especially in immature hippocampal neurons. Less clear is the nature of this structural synaptic plasticity on mature hippocampal neurons, and nothing is known about the structural plasticity of inhibitory synapses during LTP. Here the timing and extent of structural synaptic plasticity and changes in local protein synthesis evidenced by polyribosomes were systematically evaluated at both excitatory and inhibitory synapses on CA1 dendrites from mature rats following induction of LTP with theta-burst stimulation (TBS). Recent work suggests dendritic segments can act as functional units of plasticity. To test whether structural synaptic plasticity is similarly coordinated, we reconstructed from serial section transmission electron microscopy all of the spines and synapses along representative dendritic segments receiving control stimulation or TBS-LTP. At 5 min after TBS, polyribosomes were elevated in large spines suggesting an initial burst of local protein synthesis, and by 2 h only those spines with further enlarged synapses contained polyribosomes. Rapid induction of synaptogenesis was evidenced by an elevation in asymmetric shaft synapses and stubby spines at 5 min and more nonsynaptic filopodia at 30 min. By 2 h, the smallest synaptic spines were markedly reduced in number. This synapse loss was perfectly counterbalanced by enlargement of the remaining excitatory synapses such that the summed synaptic surface area per length of dendritic segment was constant across time and conditions. Remarkably, the inhibitory synapses showed a parallel synaptic plasticity, also demonstrating a decrease in number perfectly counterbalanced by an increase in synaptic surface area. Thus, TBS-LTP triggered spinogenesis followed by loss of small excitatory and inhibitory synapses and a subsequent enlargement of the remaining synapses by 2 h. These data suggest that dendritic segments coordinate structural plasticity across multiple synapses and maintain a homeostatic balance of excitatory and inhibitory inputs through local protein-synthesis and selective capture or redistribution of dendritic resources.
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Affiliation(s)
- Jennifer N Bourne
- Center for Learning and Memory, Section of Neurobiology, Institute for Neuroscience, University of Texas, Austin, Texas 78712, USA
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Kraev I, Henneberger C, Rossetti C, Conboy L, Kohler LB, Fantin M, Jennings A, Venero C, Popov V, Rusakov D, Stewart MG, Bock E, Berezin V, Sandi C. A peptide mimetic targeting trans-homophilic NCAM binding sites promotes spatial learning and neural plasticity in the hippocampus. PLoS One 2011; 6:e23433. [PMID: 21887252 PMCID: PMC3160849 DOI: 10.1371/journal.pone.0023433] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 07/17/2011] [Indexed: 01/10/2023] Open
Abstract
The key roles played by the neural cell adhesion molecule (NCAM) in plasticity and cognition underscore this membrane protein as a relevant target to develop cognitive-enhancing drugs. However, NCAM is a structurally and functionally complex molecule with multiple domains engaged in a variety of actions, which raise the question as to which NCAM fragment should be targeted. Synthetic NCAM mimetic peptides that mimic NCAM sequences relevant to specific interactions allow identification of the most promising targets within NCAM. Recently, a decapeptide ligand of NCAM—plannexin, which mimics a homophilic trans-binding site in Ig2 and binds to Ig3—was developed as a tool for studying NCAM's trans-interactions. In this study, we investigated plannexin's ability to affect neural plasticity and memory formation. We found that plannexin facilitates neurite outgrowth in primary hippocampal neuronal cultures and improves spatial learning in rats, both under basal conditions and under conditions involving a deficit in a key plasticity-promoting posttranslational modification of NCAM, its polysialylation. We also found that plannexin enhances excitatory synaptic transmission in hippocampal area CA1, where it also increases the number of mushroom spines and the synaptic expression of the AMPAR subunits GluA1 and GluA2. Altogether, these findings provide compelling evidence that plannexin is an important facilitator of synaptic functional, structural and molecular plasticity in the hippocampal CA1 region, highlighting the fragment in NCAM's Ig3 module where plannexin binds as a novel target for the development of cognition-enhancing drugs.
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Affiliation(s)
- Igor Kraev
- Department of Life Sciences, The Open University, Milton Keynes, United Kingdom
| | - Christian Henneberger
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London (UCL), London, United Kingdom
| | - Clara Rossetti
- Laboratory of Behavioral Genetics, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Lisa Conboy
- Laboratory of Behavioral Genetics, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Lene B. Kohler
- Protein Laboratory, Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Martina Fantin
- Laboratory of Behavioral Genetics, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Alistair Jennings
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London (UCL), London, United Kingdom
| | - Cesar Venero
- Department of Psychobiology, UNED, Ciudad Universitaria, Madrid, Spain
| | - Victor Popov
- Department of Life Sciences, The Open University, Milton Keynes, United Kingdom
| | - Dmitri Rusakov
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London (UCL), London, United Kingdom
| | - Michael G. Stewart
- Department of Life Sciences, The Open University, Milton Keynes, United Kingdom
- * E-mail: (CS); (MGS)
| | - Elisabeth Bock
- Protein Laboratory, Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Vladimir Berezin
- Protein Laboratory, Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Carmen Sandi
- Laboratory of Behavioral Genetics, Brain Mind Institute, EPFL, Lausanne, Switzerland
- * E-mail: (CS); (MGS)
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Calcium/calmodulin-dependent protein kinase II mediates group I metabotropic glutamate receptor-dependent protein synthesis and long-term depression in rat hippocampus. J Neurosci 2011; 31:7380-91. [PMID: 21593322 DOI: 10.1523/jneurosci.6656-10.2011] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activation of Group I metabotropic glutamate receptors (mGluRs) in rat hippocampus induces a form of long-term depression (LTD) that is dependent on protein synthesis. However, the intracellular mechanisms leading to the initiation of protein synthesis and expression of LTD after mGluR activation are only partially understood. We investigated the role of several pathways linked to mGluR activation, translation initiation, and induction of LTD. We found that Group I mGluR-dependent protein synthesis and associated LTD, as induced by the agonist (RS)-3,5-dihydrophenylglycine (DHPG) or paired-pulse synaptic stimulation, was dependent on activation of calcium/calmodulin-dependent protein kinase IIα (CaMKII). DHPG induced a transient increase in the level of phospho-CaMKII (phospho-CaMKII(T286)) in synaptoneurosomes prepared from whole hippocampus and in CA1 minislices. In synaptoneurosomes, DHPG also induced an increase in phosphorylation of eIF4E, and an increase in protein synthesis that was abolished by translation inhibitors and the CaMKII inhibitors 1-[N,O-bis(5-isoquinolinesulphonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine (KN62) and 2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)amino-N-(4-chloro-cinnamyl)-N-methylbenzylamine (KN93). In field recordings from CA1, both the translation inhibitor cycloheximide and KN62 significantly reduced DHPG-induced LTD. Combined application did not further reduce the LTD, suggesting a common mechanism. In whole-cell recordings, a third CaMKII inhibitor, AIP (autocamtide-2-related inhibitory peptide), significantly reduced the DHPG-induced LTD of synaptic currents. Inhibition of the classical pathway mediating many Group I mGluR effects by blocking PKC (protein kinase C) or PLC (phospholipase C) did not impair DHPG-induced protein synthesis or LTD. Collectively, these findings demonstrate an important role for CaMKII in mediating the initiation of protein synthesis that then supports the postsynaptic expression of DHPG-induced LTD.
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Salah A, Perkins KL. Persistent ictal-like activity in rat entorhinal/perirhinal cortex following washout of 4-aminopyridine. Epilepsy Res 2011; 94:163-76. [PMID: 21353480 DOI: 10.1016/j.eplepsyres.2011.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 01/25/2011] [Accepted: 01/26/2011] [Indexed: 11/27/2022]
Abstract
Application of 4-aminopyridine (4-AP, 100μM) in a solution containing 0.6mM Mg(2+) and 1.2mM Ca(2+) to hippocampal-entorhinal-perirhinal slices of adult rat brain induced ictal-like epileptiform activity in entorhinal and perirhinal cortices as revealed by electrophysiological field potential recordings. The ictal-like activity persisted after washing out the 4-AP. This persistence indicated that a change had occurred in the slice so that it was now "epileptic" in the absence of the convulsant 4-AP. Induction of persistent ictal-like activity was dependent upon the concentration of divalent cations during 4-AP exposure; that is, although 4-AP caused ictal-like activity in approximately half the slices in solution containing 1.6mM Mg(2+) and 2.0mM Ca(2+), this ictal-like activity did not persist upon washout of the 4-AP. Expression of the persistent ictal-like epileptiform activity required ionotropic glutamate-mediated synaptic transmission: application of the AMPA/kainate receptor antagonist NBQX after 4-AP washout reduced persistent ictal-like activity, and the combined application of NBQX and the NMDA receptor antagonist d-AP5 completely blocked it. In order to investigate the mechanism of induction of persistent ictal-like activity, several agents were applied before the introduction of 4-AP. Application of d-AP5 did not block the onset of ictal-like activity upon introduction of 4-AP but did prevent the persistence of the ictal-like activity upon washout of the 4-AP. In contrast, induction of persistent ictal-like activity was not prevented by simultaneous application of the group I metabotropic glutamate receptor (mGluR) antagonists LY 367385 and MPEP or by application of the protein synthesis inhibitor cycloheximide. In conclusion, we have characterized a new in vitro model of epileptogenesis in which induction of ictal-like activity is dependent upon NMDA receptor activation but not upon group I mGluR activation or protein synthesis.
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Affiliation(s)
- Alejandro Salah
- Program in Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, United States
| | - Katherine L Perkins
- Program in Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, United States; Department of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, United States; Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, NY 11203, United States
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41
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Tenorio G, Connor SA, Guévremont D, Abraham WC, Williams J, O'Dell TJ, Nguyen PV. 'Silent' priming of translation-dependent LTP by ß-adrenergic receptors involves phosphorylation and recruitment of AMPA receptors. Learn Mem 2010; 17:627-38. [PMID: 21097606 DOI: 10.1101/lm.1974510] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The capacity for long-term changes in synaptic efficacy can be altered by prior synaptic activity, a process known as "metaplasticity." Activation of receptors for modulatory neurotransmitters can trigger downstream signaling cascades that persist beyond initial receptor activation and may thus have metaplastic effects. Because activation of β-adrenergic receptors (β-ARs) strongly enhances the induction of long-term potentiation (LTP) in the hippocampal CA1 region, we examined whether activation of these receptors also had metaplastic effects on LTP induction. Our results show that activation of β-ARs induces a protein synthesis-dependent form of metaplasticity that primes the future induction of late-phase LTP by a subthreshold stimulus. β-AR activation also induced a long-lasting increase in phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) GluA1 subunits at a protein kinase A (PKA) site (S845) and transiently activated extracellular signal-regulated kinase (ERK). Consistent with this, inhibitors of PKA and ERK blocked the metaplastic effects of β-AR activation. β-AR activation also induced a prolonged, translation-dependent increase in cell surface levels of GluA1 subunit-containing AMPA receptors. Our results indicate that β-ARs can modulate hippocampal synaptic plasticity by priming synapses for the future induction of late-phase LTP through up-regulation of translational processes, one consequence of which is the trafficking of AMPARs to the cell surface.
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Affiliation(s)
- Gustavo Tenorio
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Canada
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Stress at learning facilitates memory formation by regulating AMPA receptor trafficking through a glucocorticoid action. Neuropsychopharmacology 2010; 35:674-85. [PMID: 19890264 PMCID: PMC3055605 DOI: 10.1038/npp.2009.172] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Stress and glucocorticoids (GCs) can facilitate memory formation. However, the molecular mechanisms mediating their effects are largely unknown. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (AMPAR) trafficking has been implicated in the changes in synaptic strength at central glutamatergic synapses associated with memory formation. In cell cultures, corticosterone has been shown to condition the synaptic trafficking of the AMPAR GluA2 subunit. In this study, we investigated the involvement of GluA2 trafficking in the facilitation of learning by stress. Using the water maze spatial task involving different stress levels, mice trained under more stressful conditions (water at 22 degrees C) showed better learning and memory, and higher post-training corticosterone levels, than mice trained under lower stress (water at 30 degrees C). Strikingly, this facilitated learning by stress was accompanied by enhanced synaptic expression of GluA2 AMPARs that was not observed in mice trained under less stressful conditions. Interfering with GC actions by injecting the GC synthesis inhibitor, metyrapone, blocked both the memory facilitation and the enhanced GluA2 trafficking induced by stressful learning. Intracerebroventricular infusion of the peptide, pep2m, that blocks GluA2 synaptic trafficking by interfering with the interaction between N-ethylmaleimide-sensitive factor and GluA2, impaired immediate performance at learning as well as long-term memory retrieval, supporting a causal role for GluA2 trafficking in stress-induced facilitation of spatial learning and memory. Evidence for the involvement of the neural cell adhesion molecule N-cadherin in interaction with GluA2 is also provided. These findings underscore a new mechanism whereby stress can improve memory function.
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43
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Dizocilpine (MK-801) induces distinct changes of N-methyl-D-aspartic acid receptor subunits in parvalbumin-containing interneurons in young adult rat prefrontal cortex. Int J Neuropsychopharmacol 2009; 12:1395-408. [PMID: 19435549 PMCID: PMC2859425 DOI: 10.1017/s146114570900042x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
N-methyl-D-aspartic acid receptor (NMDAR) hypofunction has long been implicated in schizophrenia and NMDARs on gamma-aminobutyric acid (GABA)ergic interneurons are proposed to play an essential role in the pathogenesis. However, controversial results have been reported regarding the regulation of NMDAR expression, and direct evidence of how NMDAR antagonists act on specific subpopulations of prefrontal interneurons is missing. We investigated the effects of the NMDAR antagonist dizocilpine (MK-801) on the expression of NMDAR subtypes in the identified interneurons in young adult rat prefrontal cortex (PFC) by using laser microdissection and real-time polymerase chain reaction, combined with Western blotting and immunofluorescent staining. We found that MK-801 induced distinct changes of NMDAR subunits in the parvalbumin-immunoreactive (PV-ir) interneurons vs. pyramidal neurons in the PFC circuitry. The messenger RNA (mRNA) expression of all NMDAR subtypes, including NR1 and NR2A to 2D, exhibited inverted-U dose-dependent changes in response to MK-801 treatment in the PFC. In contrast, subunit mRNAs of NMDARs in PV-ir interneurons were significantly down-regulated at low doses, unaltered at medium doses, and significantly decreased again at high doses, suggesting a biphasic dose response to MK-801. The differential effects of MK-801 in mRNA expression of NMDAR subunits were consistent with the protein expression of NR2A and NR2B subunits revealed with Western blotting and double immunofluorescent staining. These results suggest that PV-containing interneurons in the PFC exhibit a distinct responsiveness to NMDAR antagonism and that NMDA antagonist can differentially and dose-dependently regulate the functions of pyramidal neurons and GABAergic interneurons in the prefrontal cortical circuitry.
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Zhou M, Conboy L, Sandi C, Joëls M, Krugers HJ. Fear conditioning enhances spontaneous AMPA receptor-mediated synaptic transmission in mouse hippocampal CA1 area. Eur J Neurosci 2009; 30:1559-64. [PMID: 19811531 DOI: 10.1111/j.1460-9568.2009.06951.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AMPA receptor-mediated synaptic modifications in the amygdala have been reported to sustain cued fear conditioning. However, the hippocampal formation is also critically involved in fear learning. Therefore, we examined whether fear conditioning is also accompanied by changes in AMPA receptor-mediated synaptic transmission in the hippocampus. We focused on spontaneous miniature excitatory post-synaptic currents (mEPSCs). Young adult mice were trained using tone/footshock pairings and contextual/cued memories were tested 3-4 h and 1 day later. We found that the mEPSC frequency was significantly enhanced when recorded 3 h, but not 24 h, after fear conditioning training. Fear training induced a slight enhancement in the mEPSC amplitude at 3 h after training. The increased mEPSC frequency and amplitude were absent in animals that were only exposed to footshock or novelty or unpaired tone/footshock training. This implies that learning the association between context, tone and footshock transiently enhances hippocampal CA1 spontaneous synaptic transmission, which may contribute to the encoding of the fearful event.
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Affiliation(s)
- Ming Zhou
- Swammerdam Institute for Life Sciences, Center for Neuroscience, Amsterdam, The Netherlands.
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45
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Secreted amyloid precursor protein-α upregulates synaptic protein synthesis by a protein kinase G-dependent mechanism. Neurosci Lett 2009; 460:92-6. [DOI: 10.1016/j.neulet.2009.05.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 05/13/2009] [Accepted: 05/14/2009] [Indexed: 01/24/2023]
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46
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Loss of calcium channels in the cerebellum of the ataxic and epileptic stargazer mutant mouse. Brain Res 2009; 1279:156-67. [DOI: 10.1016/j.brainres.2009.04.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Accepted: 04/29/2009] [Indexed: 11/20/2022]
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47
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Pain and learning in a spinal system: contradictory outcomes from common origins. ACTA ACUST UNITED AC 2009; 61:124-43. [PMID: 19481111 DOI: 10.1016/j.brainresrev.2009.05.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 03/18/2009] [Accepted: 05/19/2009] [Indexed: 11/21/2022]
Abstract
The long-standing belief that the spinal cord serves merely as a conduit for information traveling to and from the brain is changing. Over the past decade, research has shown that the spinal cord is sensitive to response-outcome contingencies, demonstrating that spinal circuits have the capacity to modify behavior in response to differential environmental cues. If spinally transected rats are administered shock contingent on leg extension (controllable shock), they will maintain a flexion response that minimizes shock exposure. If, however, this contingency is broken, and shock is administered irrespective of limb position (uncontrollable shock), subjects cannot acquire the same flexion response. Interestingly, each of these treatments has a lasting effect on behavior; controllable shock enables future learning, while uncontrollable shock produces a long-lasting learning deficit. Here we suggest that the mechanisms underlying learning and the deficit may have evolved from machinery responsible for the spinal processing of noxious information. Experiments have shown that learning and the deficit require receptors and signaling cascades shown to be involved in central sensitization, including activation of NMDA and neurokinin receptors, as well as CaMKII. Further supporting this link between pain and learning, research has also shown that uncontrollable stimulation results in allodynia. Moreover, systemic inflammation and neonatal hindpaw injury each facilitate pain responding and undermine the ability of the spinal cord to support learning. These results suggest that the plasticity associated with learning and pain must be placed in a balance in order for adaptive outcomes to be observed.
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Santos S, Carvalho A, Caldeira M, Duarte C. Regulation of AMPA receptors and synaptic plasticity. Neuroscience 2009; 158:105-25. [DOI: 10.1016/j.neuroscience.2008.02.037] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 01/02/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
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49
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Moult PR, Milojkovic B, Harvey J. Leptin reverses long-term potentiation at hippocampal CA1 synapses. J Neurochem 2008; 108:685-96. [PMID: 19054283 DOI: 10.1111/j.1471-4159.2008.05810.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hormone leptin crosses the blood brain barrier and regulates numerous neuronal functions, including hippocampal synaptic plasticity. Here we show that application of leptin resulted in the reversal of long-term potentiation (LTP) at hippocampal CA1 synapses. The ability of leptin to depotentiate CA1 synapses was concentration-dependent and it displayed a distinct temporal profile. Leptin-induced depotentiation was not associated with any change in the paired pulse facilitation ratio or the coefficient of variance, indicating a post-synaptic locus of expression. Moreover, the synaptic activation of NMDA receptors was required for leptin-induced depotentiation as the effects of leptin were blocked by the competitive NMDA receptor antagonist, D-aminophosphovaleric acid (D-AP5). The signaling mechanisms underlying leptin-induced depotentiation involved activation of the calcium/calmodulin-dependent protein phosphatase, calcineurin, but were independent of c-jun NH(2) terminal kinase. Furthermore, leptin-induced depotentiation was accompanied by a reduction in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor rectification indicating that loss of glutamate receptor 2 (GluR2)-lacking AMPA receptors underlies this process. These data indicate that leptin reverses hippocampal LTP via a process involving calcineurin-dependent internalization of GluR2-lacking AMPA receptors which further highlights the key role for this hormone in regulating hippocampal synaptic plasticity and neuronal development.
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Affiliation(s)
- Peter R Moult
- Neurosciences Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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50
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Decker JM, Wojtowicz A, Heinemann U, Braunewell KH. C-Type natriuretic peptide modulates pre- and postsynaptic properties in hippocampal area CA1 in vitro. Biochem Biophys Res Commun 2008; 377:820-5. [DOI: 10.1016/j.bbrc.2008.10.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 10/10/2008] [Indexed: 10/24/2022]
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