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Rusakov DA, Giese KP, Sandi C, Dommett E, Overton PG. Remembering Mike Stewart. Neuropharmacology 2022; 207:108962. [PMID: 35051447 DOI: 10.1016/j.neuropharm.2022.108962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Karl Peter Giese
- Institute of Psychiatry, Physiology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Carmen Sandi
- Swiss Federal Institute of Technology in Lausanne (EPFL), Rte Cantonale, 1015, Lausanne, Switzerland
| | - Eleanore Dommett
- Institute of Psychiatry, Physiology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Paul G Overton
- Department of Psychology, University of Sheffield, Vicar Lane, Sheffield, S1 2LT, UK
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Rusakov DA, Stewart MG. Synaptic environment and extrasynaptic glutamate signals: The quest continues. Neuropharmacology 2021; 195:108688. [PMID: 34174263 DOI: 10.1016/j.neuropharm.2021.108688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/11/2022]
Abstract
Behaviour of a mammal relies on the brain's excitatory circuits equipped with glutamatergic synapses. In most cases, glutamate escaping from the synaptic cleft is rapidly buffered and taken up by high-affinity transporters expressed by nearby perisynaptic astroglial processes (PAPs). The spatial relationship between glutamatergic synapses and PAPs thus plays a crucial role in understanding glutamate signalling actions, yet its intricate features can only be fully appreciated using methods that operate beyond the diffraction limit of light. Here, we examine principal aspects pertaining to the receptor actions of glutamate, inside and outside the synaptic cleft in the brain, where the organisation of synaptic micro-physiology and micro-environment play a critical part. In what conditions and how far glutamate can escape the synaptic cleft activating its target receptors outside the immediate synapse has long been the subject of debate. Evidence is also emerging that neuronal activity- and astroglia-dependent glutamate spillover actions could be important across the spectrum of cognitive functions This article is part of the special issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Michael G Stewart
- Dept of Life Sciences, The Open University, Milton Keynes, MK7 6AA, UK.
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Pereda-Pérez I, Valencia A, Baliyan S, Núñez Á, Sanz-García A, Zamora B, Rodríguez-Fernández R, Esteban JA, Venero C. Systemic administration of a fibroblast growth factor receptor 1 agonist rescues the cognitive deficit in aged socially isolated rats. Neurobiol Aging 2019; 78:155-165. [PMID: 30928883 DOI: 10.1016/j.neurobiolaging.2019.02.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 01/22/2019] [Accepted: 02/09/2019] [Indexed: 11/20/2022]
Abstract
Social isolation predominantly occurs in elderly people and it is strongly associated with cognitive decline. However, the mechanisms that produce isolation-related cognitive dysfunction during aging remain unclear. Here, we evaluated the cognitive, electrophysiological, and morphological effects of short- (4 weeks) and long-term (12 weeks) social isolation in aged male Wistar rats. Long-term but not short-term social isolation increased the plasma corticosterone levels and impaired spatial memory in the Morris water maze. Moreover, isolated animals displayed dampened hippocampal long-term potentiation in vivo, both in the dentate gyrus (DG) and CA1, as well as a specific reduction in the volume of the stratum oriens and spine density in CA1. Interestingly, social isolation induced a transient increase in hippocampal basic fibroblast growth factor (FGF2), whereas fibroblast growth factor receptor 1 (FGFR1) levels only increased after long-term isolation. Importantly, subchronic systemic administration of FGL, a synthetic peptide that activates FGFR1, rescued spatial memory in long-term isolated rats. These findings provide new insights into the neurobiological mechanisms underlying the detrimental effects on memory of chronic social isolation in the aged.
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Affiliation(s)
- Inmaculada Pereda-Pérez
- Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain; Faculty of Experimental Sciences, Universidad Francisco de Vitoria, UFV, Madrid, Spain
| | - Azucena Valencia
- Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Shishir Baliyan
- Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain
| | - Ángel Núñez
- School of Medicine, Autonoma University of Madrid, Madrid, Spain
| | - Ancor Sanz-García
- Unidad de Análisis de datos, Instituto de Investigación Sanitaria Hospital de la Princesa, Madrid, Spain
| | - Berta Zamora
- Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain; Fetal Medicine Unit-SAMID, Department of Obstetrics and Gynecology, Hospital Universitario, Madrid, Spain
| | - Raquel Rodríguez-Fernández
- Department of Behavioural Sciences Methodology, Universidad Nacional de Educación a Distancia, Madrid, Spain
| | - José Antonio Esteban
- Department of Molecular Neurobiology, Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas (CSIC) / Universidad Autónoma de Madrid, Madrid, Spain
| | - César Venero
- Department of Psychobiology, Universidad Nacional de Educación a Distancia (UNED), Madrid, Spain.
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NCAM Mimetic Peptides: Potential Therapeutic Target for Neurological Disorders. Neurochem Res 2018; 43:1714-1722. [DOI: 10.1007/s11064-018-2594-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 06/27/2018] [Accepted: 07/06/2018] [Indexed: 10/28/2022]
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Borland H, Vilhardt F. Prelysosomal Compartments in the Unconventional Secretion of Amyloidogenic Seeds. Int J Mol Sci 2017; 18:ijms18010227. [PMID: 28124989 PMCID: PMC5297856 DOI: 10.3390/ijms18010227] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/09/2017] [Accepted: 01/16/2017] [Indexed: 12/18/2022] Open
Abstract
A mechanistic link between neuron-to-neuron transmission of secreted amyloid and propagation of protein malconformation cytopathology and disease has recently been uncovered in animal models. An enormous interest in the unconventional secretion of amyloids from neurons has followed. Amphisomes and late endosomes are the penultimate maturation products of the autophagosomal and endosomal pathways, respectively, and normally fuse with lysosomes for degradation. However, under conditions of perturbed membrane trafficking and/or lysosomal deficiency, prelysosomal compartments may instead fuse with the plasma membrane to release any contained amyloid. After a brief introduction to the endosomal and autophagosomal pathways, we discuss the evidence for autophagosomal secretion (exophagy) of amyloids, with a comparative emphasis on Aβ1-42 and α-synuclein, as luminal and cytosolic amyloids, respectively. The ESCRT-mediated import of cytosolic amyloid into late endosomal exosomes, a known vehicle of transmission of macromolecules between cells, is also reviewed. Finally, mechanisms of lysosomal dysfunction, deficiency, and exocytosis are exemplified in the context of genetically identified risk factors, mainly for Parkinson's disease. Exocytosis of prelysosomal or lysosomal organelles is a last resort for clearance of cytotoxic material and alleviates cytopathy. However, they also represent a vehicle for the concentration, posttranslational modification, and secretion of amyloid seeds.
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Affiliation(s)
- Helena Borland
- Department of Neurodegeneration In Vitro, H. Lundbeck A/S, 2500 Valby, Denmark.
| | - Frederik Vilhardt
- Department of Cellular and Molecular Medicine, Panum Institute, University of Copenhagen, 2200N Copenhagen, Denmark.
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Ultrastructural Changes in the White and Gray Matter of Mice at Chronic Time Points After Repeated Concussive Head Injury. J Neuropathol Exp Neurol 2015; 74:1012-35. [DOI: 10.1097/nen.0000000000000247] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Klein R, Blaschke S, Neumaier B, Endepols H, Graf R, Keuters M, Hucklenbroich J, Albrechtsen M, Rees S, Fink GR, Schroeter M, Rueger MA. The synthetic NCAM mimetic peptide FGL mobilizes neural stem cells in vitro and in vivo. Stem Cell Rev Rep 2015; 10:539-47. [PMID: 24817672 DOI: 10.1007/s12015-014-9512-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The neural cell adhesion molecule (NCAM) plays a role in neurite outgrowth, synaptogenesis, and neuronal differentiation. The NCAM mimetic peptide FG Loop (FGL) promotes neuronal survival in vitro and enhances spatial learning and memory in rats. We here investigated the effects of FGL on neural stem cells (NSC) in vitro and in vivo. In vitro, cell proliferation of primary NSC was assessed after exposure to various concentrations of NCAM or FGL. The differentiation potential of NCAM- or FGL-treated cells was assessed immunocytochemically. To investigate its influence on endogenous NSC in vivo, FGL was injected subcutaneously into adult rats. The effects on NSC mobilization were studied both via non-invasive positron emission tomography (PET) imaging using the tracer [(18)F]-fluoro-L-thymidine ([(18)F]FLT), as well as with immunohistochemistry. Only FGL significantly enhanced NSC proliferation in vitro, with a maximal effect at 10 μg/ml. During differentiation, NCAM promoted neurogenesis, while FGL induced an oligodendroglial phenotype; astrocytic differentiation was neither affected by NCAM or FGL. Those differential effects of NCAM and FGL on differentiation were mediated through different receptors. After FGL-injection in vivo, proliferative activity of NSC in the subventricular zone (SVZ) was increased (compared to placebo-treated animals). Moreover, non-invasive imaging of cell proliferation using [(18)F]FLT-PET supported an FGL-induced mobilization of NSC from both the SVZ and the hippocampus. We conclude that FGL robustly induces NSC mobilization in vitro and in vivo, and supports oligodendroglial differentiation. This capacity renders FGL a promising agent to facilitate remyelinization, which may eventually make FGL a drug candidate for demyelinating neurological disorders.
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Affiliation(s)
- Rebecca Klein
- Department of Neurology, University Hospital of Cologne, Kerpener Strasse 62, 50924, Cologne, Germany
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Information handling by the brain: proposal of a new "paradigm" involving the roamer type of volume transmission and the tunneling nanotube type of wiring transmission. J Neural Transm (Vienna) 2014; 121:1431-49. [PMID: 24866694 DOI: 10.1007/s00702-014-1240-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 05/06/2014] [Indexed: 12/13/2022]
Abstract
The current view on the organization of the central nervous system (CNS) is basically anchored to the paradigm describing the brain as formed by networks of neurons interconnected by synapses. Synaptic contacts are a fundamental characteristic for describing CNS operations, but increasing evidence accumulated in the last 30 years pointed to a refinement of this view. A possible overcoming of the classical "neuroscience paradigm" will be here outlined, based on the following hypotheses: (1) the basic morpho-functional unit in the brain is a compartment of tissue (functional module) where different resident cells (not only neurons) work as an integrated unit; (2) in these complex networks, a spectrum of intercellular communication processes is exploited, that can be classified according to a dichotomous criterion: wiring transmission (occurring through physically delimited channels) and volume transmission (exploiting diffusion in the extracellular space); (3) the connections between cells can themselves be described as a network, leading to an information processing occurring at different levels from cell network down to molecular level; (4) recent evidence of the existence of specialized structures (microvesicles and tunneling nanotubes) for intercellular exchange of materials, could allow a further type of polymorphism of the CNS networks based on at least transient changes in cell phenotype. When compared to the classical paradigm, the proposed scheme of cellular organization could allow a strong increase of the degrees of freedom available to the whole system and then of its plasticity. Furthermore, long range coordination and correlation can be more easily accommodated within this framework.
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Zellinger C, Salvamoser JD, Seeger N, Russmann V, Potschka H. Impact of the neural cell adhesion molecule-derived peptide FGL on seizure progression and cellular alterations in the mouse kindling model. ACS Chem Neurosci 2014; 5:185-93. [PMID: 24456603 DOI: 10.1021/cn400153g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The neural cell adhesion molecule peptide mimetic fibroblast growth loop (FGL) proved to exert neuroprotective, neurotrophic, and anti-inflammatory effects in different in vitro and in vivo experiments. Based on this beneficial efficacy profile, it is currently in clinical development for neurodegenerative diseases and brain insults. Here, we addressed the hypothesis that the peptide might affect development of seizures in a kindling paradigm, as well as associated behavioral and cellular alterations. Both doses tested, 2 and 10 mg/kg FGL, significantly reduced the number of stimulations necessary to induce a generalized seizure. FGL did not exert relevant effects on the behavioral patterns of kindled animals. As expected, kindling increased the hippocampal cell proliferation rate. Whereas the low dose of FGL did not affect this kindling-associated alteration, 10 mg/kg FGL proved to attenuate the expansion of the doublecortin-positive cell population. These data suggest that FGL administration might have an impact on disease-associated alterations in the hippocampal neuronal progenitor cell population. In conclusion, the effects of the peptide mimetic FGL in the kindling model do not confirm a disease-modifying effect with a beneficial impact on the development or course of epilepsy. The results obtained with FGL rather raise some concern regarding a putative effect, which might promote the formation of a hyperexcitable network. Future studies are required to further assess the risks in models with development of spontaneous seizures.
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Affiliation(s)
- Christina Zellinger
- Institute
of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Koeniginstrasse 16, D-80539 Munich, Germany
| | - Josephine D. Salvamoser
- Institute
of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Koeniginstrasse 16, D-80539 Munich, Germany
| | - Natalie Seeger
- Institute
of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Koeniginstrasse 16, D-80539 Munich, Germany
| | - Vera Russmann
- Institute
of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Koeniginstrasse 16, D-80539 Munich, Germany
| | - Heidrun Potschka
- Institute
of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Koeniginstrasse 16, D-80539 Munich, Germany
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Corbett NJ, Gabbott PL, Klementiev B, Davies HA, Colyer FM, Novikova T, Stewart MG. Amyloid-beta induced CA1 pyramidal cell loss in young adult rats is alleviated by systemic treatment with FGL, a neural cell adhesion molecule-derived mimetic peptide. PLoS One 2013; 8:e71479. [PMID: 23951173 PMCID: PMC3739720 DOI: 10.1371/journal.pone.0071479] [Citation(s) in RCA: 18] [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: 02/08/2013] [Accepted: 06/29/2013] [Indexed: 12/24/2022] Open
Abstract
Increased levels of neurotoxic amyloid-beta in the brain are a prominent feature of Alzheimer's disease. FG-Loop (FGL), a neural cell adhesion molecule-derived peptide that corresponds to its second fibronectin type III module, has been shown to provide neuroprotection against a range of cellular insults. In the present study impairments in social recognition memory were seen 24 days after a 5 mg/15 µl amyloid-beta(25-35) injection into the right lateral ventricle of the young adult rat brain. This impairment was prevented if the animal was given a systemic treatment of FGL. Unbiased stereology was used to investigate the ability of FGL to alleviate the deleterious effects on CA1 pyramidal cells of the amyloid-beta(25-35) injection. NeuN, a neuronal marker (for nuclear staining) was used to identify pyramidal cells, and immunocytochemistry was also used to identify inactive glycogen synthase kinase 3beta (GSK3β) and to determine the effects of amyloid-beta(25-35) and FGL on the activation state of GSK3β, since active GSK3β has been shown to cause a range of AD pathologies. The cognitive deficits were not due to hippocampal atrophy as volume estimations of the entire hippocampus and its regions showed no significant loss, but amyloid-beta caused a 40% loss of pyramidal cells in the dorsal CA1 which was alleviated partially by FGL. However, FGL treatment without amyloid-beta was also found to cause a 40% decrease in CA1 pyramidal cells. The action of FGL may be due to inactivation of GSK3β, as an increased proportion of CA1 pyramidal neurons contained inactive GSK3β after FGL treatment. These data suggest that FGL, although potentially disruptive in non-pathological conditions, can be neuroprotective in disease-like conditions.
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Affiliation(s)
- Nicola J Corbett
- Open University, Department of Life, Health and Chemical Sciences, Milton Keynes, United Kingdom.
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Age-Induced Loss of Mossy Fibre Synapses on CA3 Thorns in the CA3 Stratum Lucidum. NEUROSCIENCE JOURNAL 2013; 2013:839535. [PMID: 26317100 PMCID: PMC4437271 DOI: 10.1155/2013/839535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/19/2013] [Indexed: 01/08/2023]
Abstract
Advanced ageing is associated with hippocampal deterioration and mild cognitive decline. The hippocampal subregion CA3 stratum lucidum (CA3-SL) receives neuronal inputs from the giant mossy fibre boutons of the dentate gyrus, but relatively little is known about the integrity of this synaptic connection with ageing. Using serial electron microscopy and unbiased stereology, we examined age-related changes in mossy fibre synapses on CA3 thorny excrescences within the CA3-SL of young adults (4-month-old), middle-aged (12-month-old), and old-aged (28-month-old) Wistar rats. Our data show that while there is an increase in CA3 volume with ageing, there is a significant (40–45%) reduction in synaptic density within the CA3-SL of 12- and 28-month-old animals compared with 4-month-old animals. We also present preliminary data showing that the CA3 neuropil in advanced ageing was conspicuously full of lipofuscin and phagolysosome positive, activated microglial cellular processes, and altered perivascular pathology. These data suggest that synaptic density in the CA3-SL is significantly impaired in ageing, accompanied by underlying prominent ultrastructural glial and microvascular changes.
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Bisaz R, Boadas-Vaello P, Genoux D, Sandi C. Age-related cognitive impairments in mice with a conditional ablation of the neural cell adhesion molecule. Learn Mem 2013; 20:183-93. [PMID: 23504516 DOI: 10.1101/lm.030064.112] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Most of the mechanisms involved in neural plasticity support cognition, and aging has a considerable effect on some of these processes. The neural cell adhesion molecule (NCAM) of the immunoglobulin superfamily plays a pivotal role in structural and functional plasticity and is required to modulate cognitive and emotional behaviors. However, whether aging is associated with NCAM alterations that might contribute to age-related cognitive decline is not currently known. In this study, we determined whether conditional NCAM-deficient mice display increased vulnerability to age-related cognitive and emotional alterations. We assessed the NCAM expression levels in the hippocampus and medial prefrontal cortex (mPFC) and characterized the performance of adult and aged conditional NCAM-deficient mice and their age-matched wild-type littermates in a delayed matching-to-place test in the Morris water maze and a delayed reinforced alternation test in the T-maze. Although aging in wild-type mice is associated with an isoform-specific reduction of NCAM expression levels in the hippocampus and mPFC, these mice exhibited only mild impairments in working/episodic-like memory performance. However, aged conditional NCAM-deficient mice displayed pronounced impairments in both the delayed matching-to-place and the delayed reinforced alternation tests. Importantly, the deficits of aged NCAM-deficient mice in these working/episodic-like memory tasks could not be attributed to increased anxiety-like behaviors or to differences in locomotor activity. Taken together, these data indicate that reduced NCAM expression in the forebrain might be a critical factor for the occurrence of cognitive impairments during aging.
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Affiliation(s)
- Reto Bisaz
- Laboratory of Behavioral Genetics, Brain Mind Institute, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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NCAM function in the adult brain: lessons from mimetic peptides and therapeutic potential. Neurochem Res 2013; 38:1163-73. [PMID: 23494903 DOI: 10.1007/s11064-013-1007-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 02/01/2013] [Accepted: 02/18/2013] [Indexed: 01/22/2023]
Abstract
Neural cell adhesion molecules (NCAMs) are complexes of transmembranal proteins critical for cell-cell interactions. Initially recognized as key players in the orchestration of developmental processes involving cell migration, cell survival, axon guidance, and synaptic targeting, they have been shown to retain these functions in the mature adult brain, in relation to plastic processes and cognitive abilities. NCAMs are able to interact among themselves (homophilic binding) as well as with other molecules (heterophilic binding). Furthermore, they are the sole molecule of the central nervous system undergoing polysialylation. Most interestingly polysialylated and non-polysialylated NCAMs display opposite properties. The precise contributions each of these characteristics brings in the regulations of synaptic and cellular plasticity in relation to cognitive processes in the adult brain are not yet fully understood. With the aim of deciphering the specific involvement of each interaction, recent developments led to the generation of NCAM mimetic peptides that recapitulate identified binding properties of NCAM. The present review focuses on the information such advances have provided in the understanding of NCAM contribution to cognitive function.
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Multiple spine boutons are formed after long-lasting LTP in the awake rat. Brain Struct Funct 2012; 219:407-14. [PMID: 23224218 DOI: 10.1007/s00429-012-0488-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/16/2012] [Indexed: 01/25/2023]
Abstract
The formation of multiple spine boutons (MSBs) has been associated with cognitive abilities including hippocampal-dependent associative learning and memory. Data obtained from cultured hippocampal slices suggest that the long-term maintenance of synaptic plasticity requires the formation of new synaptic contacts on pre-existing synapses. This postulate however, has never been tested in the awake, freely moving animals. In the current study, we induced long-term potentiation (LTP) in the dentate gyrus (DG) of awake adult rats and performed 3-D reconstructions of electron micrographs from thin sections of both axonal boutons and dendritic spines, 24 h post-induction. The specificity of the observed changes was demonstrated by comparison with animals in which long-term depression (LTD) had been induced, or with animals in which LTP was blocked by an N-methyl-D-aspartate (NMDA) antagonist. Our data demonstrate that whilst the number of boutons remains unchanged, there is a marked increase in the number of synapses per bouton 24 h after the induction of LTP. Further, we demonstrate that this increase is specific to mushroom spines and not attributable to their division. The present investigation thus fills the gap existing between behavioural and in vitro studies on the role of MSB formation in synaptic plasticity and cognitive abilities.
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Ojo B, Gabbott PL, Rezaie P, Corbett N, Medvedev NI, Cowley TR, Lynch MA, Stewart MG. An NCAM mimetic, FGL, alters hippocampal cellular morphometry in young adult (4 month-old) rats. Neurochem Res 2012; 38:1208-18. [PMID: 23076631 DOI: 10.1007/s11064-012-0908-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/16/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022]
Abstract
The neural cell adhesion molecule, NCAM, is ubiquitously expressed within the CNS and has roles in development, cognition, neural plasticity and regulation of the immune system. NCAM is thus potentially an important pharmacological target for treatment of brain diseases. A cell adhesion mimetic FGL, a 15 amino-acid peptide derived from the second fibronectin type-III module of NCAM, has been shown to act as a neuroprotective agent in experimental disease and ageing models, restoring hippocampal/cognitive function and markedly alleviating deleterious changes in the CNS. However, the effects of FGL on the hippocampus of young healthy rats are unknown. The present study has examined the cellular neurobiological consequences of subcutaneous injections of FGL, on hippocampal cell morphometry in young (4 month-old) rats. We determined the effects of FGL on hippocampal volume, pyramidal neuron number/density (using unbiased quantitative stereology), and examined aspects of neurogenesis (using 2D morphometric analyses). FGL treatment reduced total volume of the dorsal hippocampus (associated with a decrease in total pyramidal neuron numbers in CA1 and CA3), and elevated the number of doublecortin immunolabeled neurons in the dentate gyrus, indicating a likely influence on neurogenesis in young healthy rats. These data indicate that FGL has a specific age dependent effect on the hippocampus, differing according to the development and maturity of the CNS.
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Affiliation(s)
- Bunmi Ojo
- Department of Life, Health and Chemical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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Age-related changes in the hippocampus (loss of synaptophysin and glial-synaptic interaction) are modified by systemic treatment with an NCAM-derived peptide, FGL. Brain Behav Immun 2012; 26:778-88. [PMID: 21986303 DOI: 10.1016/j.bbi.2011.09.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/24/2011] [Accepted: 09/27/2011] [Indexed: 12/21/2022] Open
Abstract
Altered synaptic morphology, progressive loss of synapses and glial (astrocyte and microglial) cell activation are considered as characteristic hallmarks of aging. Recent evidence suggests that there is a concomitant age-related decrease in expression of the presynaptic protein, synaptophysin, and the neuronal glycoprotein CD200, which, by interacting with its receptor, plays a role in maintaining microglia in a quiescent state. These age-related changes may be indicative of reduced neuroglial support of synapses. FG Loop (FGL) peptide synthesized from the second fibronectin type III module of neural cell adhesion molecule (NCAM), has previously been shown to attenuate age-related glial cell activation, and to 'restore' cognitive function in aged rats. The mechanisms by which FGL exerts these neuroprotective effects remain unclear, but could involve regulation of CD200, modifying glial-synaptic interactions (affecting neuroglial 'support' at synapses), or impacting directly on synaptic function. Light and electron microscopic (EM) analyses were undertaken to investigate whether systemic treatment with FGL (i) alters CD200, synaptophysin (presynaptic) and PSD-95 (postsynaptic) immunohistochemical expression levels, (ii) affects synaptic number, or (iii) exerts any effects on glial-synaptic interactions within young (4 month-old) and aged (22 month-old) rat hippocampus. Treatment with FGL attenuated the age-related loss of synaptophysin immunoreactivity (-ir) within CA3 and hilus (with no major effect on PSD-95-ir), and of CD200-ir specifically in the CA3 region. Ultrastructural morphometric analyses showed that FGL treatment (i) prevented age-related loss in astrocyte-synaptic contacts, (ii) reduced microglia-synaptic contacts in the CA3 stratum radiatum, but (iii) had no effect on the mean number of synapses in this region. These data suggest that FGL mediates its neuroprotective effects by regulating glial-synaptic interaction.
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Chivet M, Hemming F, Pernet-Gallay K, Fraboulet S, Sadoul R. Emerging role of neuronal exosomes in the central nervous system. Front Physiol 2012; 3:145. [PMID: 22654762 PMCID: PMC3361079 DOI: 10.3389/fphys.2012.00145] [Citation(s) in RCA: 164] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 04/30/2012] [Indexed: 12/24/2022] Open
Abstract
Exosomes are small extracellular vesicles, which stem from endosomes fusing with the plasma membrane, and can be recaptured by receiving cells. They contain lipids, proteins, and RNAs able to modify the physiology of receiving cells. Functioning of the brain relies on intercellular communication between neural cells. These communications can modulate the strength of responses at sparse groups of specific synapses, to modulate circuits underlying associations and memory. Expression of new genes must then follow to stabilize the long-term modifications of the synaptic response. Local changes of the physiology of synapses from one neuron driven by another, have so far been explained by classical signal transduction to modulate transcription, translation, and posttranslational modifications. In vitro evidence now demonstrates that exosomes are released by neurons in a way depending on synaptic activity; these exosomes can be retaken by other neurons suggesting a novel way for inter-neuronal communication. The efficacy of inter-neuronal transfer of biochemical information allowed by exosomes would be far superior to that of direct cell-to-cell contacts or secreted soluble factors. Indeed, lipids, proteins, and RNAs contained in exosomes secreted by emitting neurons could directly modify signal transduction and protein expression in receiving cells. Exosomes could thus represent an ideal mechanism for inter-neuronal transfer of information allowing anterograde and retrograde signaling across synapses necessary for plasticity. They might also allow spreading across the nervous system of pathological proteins like PrPsc, APP fragments, phosphorylated Tau, or Alpha-synuclein.
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Affiliation(s)
- Mathilde Chivet
- U836, Equipe 2, Neurodégénérescence et Plasticité, INSERM Grenoble, France
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A neural cell adhesion molecule-derived peptide, FGL, attenuates glial cell activation in the aged hippocampus. Exp Neurol 2011; 232:318-28. [DOI: 10.1016/j.expneurol.2011.09.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 08/10/2011] [Accepted: 09/15/2011] [Indexed: 01/09/2023]
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Michaluk P, Wawrzyniak M, Alot P, Szczot M, Wyrembek P, Mercik K, Medvedev N, Wilczek E, De Roo M, Zuschratter W, Muller D, Wilczynski GM, Mozrzymas JW, Stewart MG, Kaczmarek L, Wlodarczyk J. Influence of matrix metalloproteinase MMP-9 on dendritic spine morphology. J Cell Sci 2011; 124:3369-80. [PMID: 21896646 DOI: 10.1242/jcs.090852] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
An increasing body of data has shown that matrix metalloproteinase-9 (MMP-9), an extracellularly acting, Zn(2+)-dependent endopeptidase, is important not only for pathologies of the central nervous system but also for neuronal plasticity. Here, we use three independent experimental models to show that enzymatic activity of MMP-9 causes elongation and thinning of dendritic spines in the hippocampal neurons. These models are: a recently developed transgenic rat overexpressing autoactivating MMP-9, dissociated neuronal cultures, and organotypic neuronal cultures treated with recombinant autoactivating MMP-9. This dendritic effect is mediated by integrin β1 signalling. MMP-9 treatment also produces a change in the decay time of miniature synaptic currents; however, it does not change the abundance and localization of synaptic markers in dendritic protrusions. Our results, considered together with several recent studies, strongly imply that MMP-9 is functionally involved in synaptic remodelling.
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Affiliation(s)
- Piotr Michaluk
- Department of Molecular and Cellular Neurobiology, The Nencki Institute, Pasteura 3, 02-093 Warsaw, Poland.
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20
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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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Popov VI, Kleschevnikov AM, Klimenko OA, Stewart MG, Belichenko PV. Three-dimensional synaptic ultrastructure in the dentate gyrus and hippocampal area CA3 in the Ts65Dn mouse model of Down syndrome. J Comp Neurol 2011; 519:1338-54. [PMID: 21452200 DOI: 10.1002/cne.22573] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Down syndrome (DS) results from trisomy of human chromosome 21. Ts65Dn mice are an established model for DS and show several phenotypes similar to those in people with DS. However, there is little data on the structural plasticity of synapses in the trisynaptic pathway in the hippocampus. Here we investigate 3D ultrastructure of synapses in the hippocampus of age-matched control (2N) and Ts65Dn male mice. Serial ultrathin sections and 3D reconstructions characterize synapses in the middle molecular layer (MML) of dentate gyrus and in thorny excrescences (TEs) in proximal portions of apical dendrites of CA3 pyramidal neurons. 3D analysis of synapses shows phenotypes that distinguish Ts65Dn from 2N mice. For the MML, synapse density was reduced by 15% in Ts65Dn vs. 2N mice (P < 0.05). Comparative 3D analyses demonstrate a significant decrease in the number of thorns per TE in CA3 in Ts65Dn vs. 2N mice (by ≈45%, P = 0.01). Individual thorn volume was 3 times smaller in Ts65Dn vs. 2N mice (P = 0.02). A significant decrease in the number of thorn projections per TE in Ts65Dn vs. 2N mice was accompanied by a decrease of filopodium-like protrusions on the surface of TEs (P = 0.02). However, the volume of postsynaptic densities in CA3 Ts65Dn and 2N mice was unchanged (P = 0.78). Our findings suggest that the high degree of plasticity of CA3 thorns may be connected with their filopodial origin. Alterations of 3D synaptic structure in Ts65Dn mice may further contribute to the diminished plasticity in DS.
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Affiliation(s)
- Victor I Popov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia.
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22
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Dallerac G, Zerwas M, Novikova T, Callu D, Leblanc-Veyrac P, Bock E, Berezin V, Rampon C, Doyere V. The neural cell adhesion molecule-derived peptide FGL facilitates long-term plasticity in the dentate gyrus in vivo. Learn Mem 2011; 18:306-13. [DOI: 10.1101/lm.2154311] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Release of exosomes from differentiated neurons and its regulation by synaptic glutamatergic activity. Mol Cell Neurosci 2010; 46:409-18. [PMID: 21111824 DOI: 10.1016/j.mcn.2010.11.004] [Citation(s) in RCA: 421] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 10/15/2010] [Accepted: 11/12/2010] [Indexed: 12/21/2022] Open
Abstract
Exosomes are microvesicles released into the extracellular medium upon fusion to the plasma membrane of endosomal intermediates called multivesicular bodies. They represent ways for discarding proteins and metabolites and also for intercellular transfer of proteins and RNAs. In the nervous system, it has been hypothesized that exosomes might be involved in the normal physiology of the synapse and possibly allow the trans-synaptic propagation of pathogenic proteins throughout the tissue. As a first step to validate this concept, we used biochemical and morphological approaches to demonstrate that mature cortical neurons in culture do indeed secrete exosomes. Using electron microscopy, we observed exosomes being released from somato-dendritic compartments. The endosomal origin of exosomes was demonstrated by showing that the C-terminal domain of tetanus toxin specifically endocytosed by neurons and accumulating inside multivesicular bodies, is released in the extracellular medium in association with exosomes. Finally, we found that exosomal release is modulated by glutamatergic synaptic activity, suggesting that this process might be part of normal synaptic physiology. Thus, our study paves the way towards the demonstration that exosomes take part in the physiology of the normal and pathological nervous system.
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Isaeva E, Lushnikova I, Savrasova A, Skibo G, Holmes GL, Isaev D. Blockade of endogenous neuraminidase leads to an increase of neuronal excitability and activity-dependent synaptogenesis in the rat hippocampus. Eur J Neurosci 2010; 32:1889-96. [PMID: 21044183 DOI: 10.1111/j.1460-9568.2010.07468.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Polysialic acids are widely distributed in neuronal tissue. Due to their position on glycoproteins and gangliosides on the outer cell membranes and anionic nature, polysialic acids are involved in multiple cell signaling events. The level of sialylation of the cellular surface is regulated by endogenous neuraminidase (NEU), which catalyses the hydrolysis of terminal sialic acid residues. Using the specific blocker of endogenous NEU, N-acetyl-2,3-dehydro-2-deoxyneuraminic acid (NADNA), we show that downregulation of the endogenous NEU activity causes a significant increase in the level of hippocampal tissue sialylation. Acute application of NADNA increased the firing frequency and amplitude of spontaneous synchronous oscillations, and frequency of multiple unit activity in cultured hippocampal slices. The tonic phase of seizure-like activity in the low-magnesium model of ictogenesis was significantly increased in slices pretreated with NADNA. These data indicate that the degree of synchronization is influenced by the amount of active NEU in cultured hippocampal slices. Pretreatment with NADNA led to an increase of the density of simple and perforated synapses in the hippocampal CA1 stratum radiatum region. Co-incubation of slices with NADNA and high concentrations of calcium eliminated the effect of the NEU blocker on synaptic density, suggesting that synaptogenesis observed following downregulation of the endogenous NEU activity is an activity-dependent process.
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Affiliation(s)
- Elena Isaeva
- Department of General Physiology of Nervous System, Bogomoletz Institute of Physiology, Kiev, Ukraine.
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25
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Medvedev NI, Popov VI, Dallérac G, Davies HA, Laroche S, Kraev IV, Rodriguez Arellano JJ, Doyère V, Stewart MG. Alterations in synaptic curvature in the dentate gyrus following induction of long-term potentiation, long-term depression, and treatment with the N-methyl-D-aspartate receptor antagonist CPP. Neuroscience 2010; 171:390-7. [PMID: 20849931 DOI: 10.1016/j.neuroscience.2010.09.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/04/2010] [Accepted: 09/08/2010] [Indexed: 10/19/2022]
Abstract
Alterations in curvature of the post synaptic density (PSD) and apposition zone (AZ), are believed to play an important role in determining synaptic efficacy. In the present study we have examined curvature of PSDs and AZs 24 h following homosynaptic long-term potentiation (LTP), and heterosynaptic long-term depression (LTD) in vivo, in awake adult rats. High frequency stimulation (HFS) applied to the medial perforant path to the dentate gyrus induced LTP while HFS stimulation of the lateral perforant path induced LTD in the middle molecular layer of the dentate gyrus (DG). Curvature changes were analysed in this area using three dimensional (3-D) reconstructions of electron microscope images of ultrathin serial sections. Very large and significant changes in 3-D measurements of AZ and PSD curvature occurred 24 h following both LTP and LTD, with a flattening of the normal concavity of mushroom spine heads and a change to convexity for thin spines. An N-methyl-D-aspartate (NMDA) receptor antagonist CPP (3-[(R)-2-Carboxypiperazin-4-yl]-propyl-1-phosphonic acid) blocked the changes in curvature of mushroom and thin spine PSDs and apposition zones, actually increasing the concavity of mushroom spines as the spine engulfed the presynaptic bouton. In order to establish whether these changes resulted from the effect of the NMDA antagonist or from its coincidence with synaptic activation during testing we examined the effects of CPP alone on PSD and apposition zone curvature. It was found that CPP alone also caused a small decrease in curvature of both PSD and apposition zone of mushroom and thin spines.
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Affiliation(s)
- N I Medvedev
- Department of Life Sciences, The Open University, Milton Keynes, UK
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26
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Neuritogenic and neuroprotective properties of peptide agonists of the fibroblast growth factor receptor. Int J Mol Sci 2010; 11:2291-305. [PMID: 20640153 PMCID: PMC2904917 DOI: 10.3390/ijms11062291] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 05/21/2010] [Indexed: 11/17/2022] Open
Abstract
Fibroblast growth factor receptors (FGFRs) interact with their cognate ligands, FGFs, and with a number of cell adhesion molecules (CAMs), such as the neural cell adhesion molecule (NCAM), mediating a wide range of events during the development and maintenance of the nervous system. Determination of protein structure, in silico modeling and biological studies have recently resulted in the identification of FGFR binding peptides derived from various FGFs and NCAM mimicking the effects of these molecules with regard to their neuritogenic and neuroprotective properties. This review focuses on recently developed functional peptide agonists of FGFR with possible therapeutic potential.
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Rudenko O, Tkach V, Berezin V, Bock E. Effects of FGF receptor peptide agonists on animal behavior under normal and pathological conditions. Neurosci Res 2010; 68:35-43. [PMID: 20562017 DOI: 10.1016/j.neures.2010.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 04/25/2010] [Accepted: 05/10/2010] [Indexed: 01/19/2023]
Abstract
Hexafins are recently identified low-molecular-weight peptide agonists of the fibroblast growth factor receptor (FGFR), derived from the beta6-beta7 loop region of various FGFs. Synthetic hexafin peptides have been shown to bind to and induce tyrosine phosphorylation of FGFR1, stimulate neurite outgrowth, and promote neuronal survival in vitro. Thus, the pronounced biological activities of hexafins in vitro make them attractive compounds for pharmacological studies in vivo. The present study investigated the effects of subcutaneous administration of hexafin1 and hexafin2 (peptides derived from FGF1 and FGF2, respectively) on social memory, exploratory activity, and anxiety-like behavior in adult rats. Treatment with hexafin1 and hexafin2 resulted in prolonged retention of social memory. Furthermore, rats treated with hexafin2 exhibited decreased anxiety-like behavior in the elevated plus maze. Employing an R6/2 mouse model of Huntington's disease (HD), we found that although hexafin2 did not affect the progression of motor symptoms, it alleviated deficits in activity related to social behavior, including sociability and social novelty. Thus, hexafin2 may have therapeutic potential for the treatment of HD.
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Affiliation(s)
- Olga Rudenko
- Protein Laboratory, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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28
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Stewart M, Popov V, Medvedev N, Gabbott P, Corbett N, Kraev I, Davies H. Dendritic spine and synapse morphological alterations induced by a neural cell adhesion molecule mimetic. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 663:373-83. [PMID: 20017034 DOI: 10.1007/978-1-4419-1170-4_23] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Michael Stewart
- Department of Life Sciences, Faculty of Sciences, The Open University, Walton Hall, Milton Keynes, MK76AA, UK.
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29
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Medvedev N, Popov V, Rodriguez Arellano J, Dallérac G, Davies H, Gabbott P, Laroche S, Kraev I, Doyère V, Stewart M. The N-methyl-d-aspartate receptor antagonist CPP alters synapse and spine structure and impairs long-term potentiation and long-term depression induced morphological plasticity in dentate gyrus of the awake rat. Neuroscience 2010; 165:1170-81. [DOI: 10.1016/j.neuroscience.2009.11.047] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 11/16/2009] [Accepted: 11/18/2009] [Indexed: 10/20/2022]
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Role of the growth-associated protein GAP-43 in NCAM-mediated neurite outgrowth. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 663:169-82. [PMID: 20017022 DOI: 10.1007/978-1-4419-1170-4_11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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31
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Brennaman LH, Maness PF. NCAM in Neuropsychiatric and Neurodegenerative Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 663:299-317. [DOI: 10.1007/978-1-4419-1170-4_19] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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32
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Synthetic NCAM-derived ligands of the fibroblast growth factor receptor. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 663:355-72. [PMID: 20017033 DOI: 10.1007/978-1-4419-1170-4_22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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34
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Popov VI, Kraev IV, Banks D, Davies HA, Morenkov ED, Stewart MG, Fesenko EE. Three-dimensional ultrastructural and immunohistochemical study of immature neurons in the subgranular zone of the rat dentate gyrus. Biophysics (Nagoya-shi) 2009. [DOI: 10.1134/s0006350909040174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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35
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Autometallographic enhancement of the Golgi-Cox staining enables high resolution visualization of dendrites and spines. Histochem Cell Biol 2009; 132:369-74. [DOI: 10.1007/s00418-009-0611-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2009] [Indexed: 10/20/2022]
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36
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Kraev IV, Godukhin OV, Patrushev IV, Davies HA, Popov VI, Stewart MG. Partial kindling induces neurogenesis, activates astrocytes and alters synaptic morphology in the dentate gyrus of freely moving adult rats. Neuroscience 2009; 162:254-67. [PMID: 19447163 DOI: 10.1016/j.neuroscience.2009.05.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 04/30/2009] [Accepted: 05/10/2009] [Indexed: 12/01/2022]
Abstract
A partial kindling procedure was used to investigate the correlation between focal seizure development and changes in dendritic spine morphology, ongoing neurogenesis and reactive astrogliosis in the adult rat dentate gyrus (DG). The processes of neurogenesis and astrogliosis were investigated using markers for doublecortin (DCX), 5-bromo-2-deoxyuridine (BrdU) and glial fibrillary acidic protein (GFAP). Our data demonstrate that mild focal seizures induce a complex series of cellular events in the DG one day after cessation of partial rapid kindling stimulation consisting (in comparison to control animals that were electrode implanted but unkindled), firstly, of an increase in the number of postmitotic BrdU labeled cells, and secondly, an increase in the number of DCX labeled cells, mainly in subgranular zone. Ultrastructural changes were examined using qualitative electron microscope analysis and 3-D reconstructions of both dendritic spines and postsynaptic densities. Typical features of kindling in comparison to control tissue included translocation of mitochondria to the base of the dendritic spine stalks; a migration of multivesicular bodies into mushroom dendritic spines, and most notably formation of "giant" spinules originating from the head of the spines of DG neurons. These morphological alterations arise at seizure stages 2-3 (focal seizures) in the absence of signs of the severe generalized seizures that are generally recognized as potentially harmful for neuronal cells. We suggest that an increase in ongoing neurogenesis, reactive astrogliosis and dendritic spine reorganization in the DG is the crucial step in the chain of events leading to the progressive development of seizure susceptibility in hippocampal circuits.
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Affiliation(s)
- I V Kraev
- Department of Life Sciences, Faculty of Science, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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38
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Popov VI, Stewart MG. Complexity of contacts between synaptic boutons and dendritic spines in adult rat hippocampus: Three-dimensional reconstructions from serial ultrathin sections in vivo. Synapse 2009; 63:369-77. [DOI: 10.1002/syn.20613] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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39
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Korshunova I, Mosevitsky M. Role of the Growth-associated Protein GAP-43 in NCAM-mediated Neurite Outgrowth. Neurochem Res 2008. [DOI: 10.1007/s11064-008-9800-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Hansen SM, Li S, Bock E, Berezin V. WITHDRAWN: Synthetic NCAM-derived Ligands of the Fibroblast Growth Factor Receptor. Neurochem Res 2008. [PMID: 18427984 DOI: 10.1007/s11064-008-9707-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2008] [Indexed: 10/22/2022]
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41
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Stewart M, Popov V, Medvedev N, Gabbott P, Corbett N, Kraev I, Davies H. WITHDRAWN: Dendritic Spine and Synapse Morphological Alterations Induced by a Neural Cell Adhesion Molecule (NCAM) Mimetic. Neurochem Res 2008. [PMID: 18338259 DOI: 10.1007/s11064-008-9607-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 01/24/2008] [Indexed: 09/29/2022]
Abstract
The neural cell adhesion molecule (NCAM) is a glycoprotein expressed on the surface of neurons and glial cells. It plays a key role in morphogenesis of the nervous system, regeneration of damaged neural tissue and synaptic plasticity. The extracellular domain of NCAM engages in homophilic interactions (NCAM binding to NCAM) and in heterophilic interactions between NCAM and other proteins such as the fibroblast growth factor (FGF) receptor. It promotes synaptogenesis and activity-dependent remodelling of synapses but less is know of its influence on synaptic and dendritic morphology. Recently, quantitative electron microscopy and 3-dimensional reconstruction (3-D) of ultrathin serial sections has been used to examine the morphology of synapses and dendritic spines in the hippocampus of rats treated with a neural cell adhesion molecule-derived fibroblast growth factor receptor agonist, FGL-peptide (an NCAM mimetic). These data show clearly that the FGL peptide has marked influences on both spine and synaptic form.
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Affiliation(s)
- Michael Stewart
- Faculty of Sciences, Department of Life Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK,
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