1
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Hoang TH, Manahan-Vaughan D. Differentiated somatic gene expression is triggered in the dorsal hippocampus and the anterior retrosplenial cortex by hippocampal synaptic plasticity prompted by spatial content learning. Brain Struct Funct 2024; 229:639-655. [PMID: 37690045 PMCID: PMC10978647 DOI: 10.1007/s00429-023-02694-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 08/07/2023] [Indexed: 09/12/2023]
Abstract
Hippocampal afferent inputs, terminating on proximal and distal subfields of the cornus ammonis (CA), enable the functional discrimination of 'what' (item identity) and 'where' (spatial location) elements of a spatial representation. This kind of information is supported by structures such as the retrosplenial cortex (RSC). Spatial content learning promotes the expression of hippocampal synaptic plasticity, particularly long-term depression (LTD). In the CA1 region, this is specifically facilitated by the learning of item-place features of a spatial environment. Gene-tagging, by means of time-locked fluorescence in situ hybridization (FISH) to detect nuclear expression of immediate early genes, can reveal neuronal populations that engage in experience-dependent information encoding. In the current study, using FISH, we examined if learning-facilitated LTD results in subfield-specific information encoding in the hippocampus and RSC. Rats engaged in novel exploration of small items during stimulation of Schaffer collateral-CA1 synapses. This resulted in LTD (> 24 h). FISH, to detect nuclear expression of Homer1a, revealed that the distal-CA1 and proximal-CA3 subcompartments were particularly activated by this event. By contrast, all elements of the proximodistal cornus ammonis-axis showed equal nuclear Homer1a expression following LTD induction solely by means of afferent stimulation. The RSC exhibited stronger nuclear Homer1a expression in response to learning-facilitated LTD, and to novel item-place experience, compared to LTD induced by sole afferent stimulation in CA1. These results show that both the cornus ammonis and RSC engage in differentiated information encoding of item-place learning that is salient enough, in its own right, to drive the expression of hippocampal LTD. These results also reveal a novel role of the RSC in item-place learning.
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Affiliation(s)
- Thu-Huong Hoang
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Universitätsstr. 150, MA 4/150, 44780, Bochum, Germany
| | - Denise Manahan-Vaughan
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Universitätsstr. 150, MA 4/150, 44780, Bochum, Germany.
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2
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Kopach O, Sylantyev S, Bard L, Michaluk P, Heller JP, Gutierrez del Arroyo A, Ackland GL, Gourine AV, Rusakov DA. Human neutrophils communicate remotely via calcium-dependent glutamate-induced glutamate release. iScience 2023; 26:107236. [PMID: 37496680 PMCID: PMC10366500 DOI: 10.1016/j.isci.2023.107236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/25/2023] [Accepted: 06/23/2023] [Indexed: 07/28/2023] Open
Abstract
Neutrophils are white blood cells that are critical to acute inflammatory and adaptive immune responses. Their swarming-pattern behavior is controlled by multiple cellular cascades involving calcium-dependent release of various signaling molecules. Previous studies have reported that neutrophils express glutamate receptors and can release glutamate but evidence of direct neutrophil-neutrophil communication has been elusive. Here, we hold semi-suspended cultured human neutrophils in patch-clamp whole-cell mode to find that calcium mobilization induced by stimulating one neutrophil can trigger an N-methyl-D-aspartate (NMDA) receptor-driven membrane current and calcium signal in neighboring neutrophils. We employ an enzymatic-based imaging assay to image, in real time, glutamate release from neutrophils induced by glutamate released from their neighbors. These observations provide direct evidence for a positive-feedback inter-neutrophil communication that could contribute to mechanisms regulating communal neutrophil behavior.
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Affiliation(s)
- Olga Kopach
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Sergyi Sylantyev
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
- Rowett Institute, University of Aberdeen, Ashgrove Road West, Aberdeen AB25 2ZD, UK
| | - Lucie Bard
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Piotr Michaluk
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
- BRAINCITY, Laboratory of Neurobiology, Nencki Institute of Experimental Biology PAS, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Janosch P. Heller
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
- School of Biotechnology, Dublin City University, Dublin 9, Ireland
| | - Ana Gutierrez del Arroyo
- Translational Medicine and Therapeutics, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Gareth L. Ackland
- Translational Medicine and Therapeutics, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Alexander V. Gourine
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Dmitri A. Rusakov
- Queen Square Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
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3
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Boahen F, Doyon N, Deteix J. Sensitivity of the electrical response of a node of Ranvier model to alterations of the myelin sheath geometry. J Math Biol 2022; 86:17. [PMID: 36534161 DOI: 10.1007/s00285-022-01841-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 08/31/2022] [Accepted: 11/21/2022] [Indexed: 12/23/2022]
Abstract
Nodes of Ranvier play critical roles in the generation and transmission of action potentials. Alterations in node properties during pathology and/or development are known to affect the speed and quality of electrical transmission. From a modelling standpoint, nodes of Ranvier are often described by systems of ordinary differential equations neglecting or greatly simplifying their geometric structure. These approaches fail to accurately describe how fine scale alteration in the node geometry or in myelin thickness in the paranode region will impact action potential generation and transmission. Here, we rely on a finite element approximation to describe the three dimensional geometry of a node of Ranvier. With this, we are able to investigate how sensitive is the electrical response to alterations in the myelin sheath and paranode geometry. We could in particular investigate irregular loss of myelin, which might be more physiologically relevant than the uniform loss often described through simpler modelling approaches.
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Affiliation(s)
- Frank Boahen
- Groupe Interdisciplinaire de Recherche en Éléments Finis (GIREF), Département de mathématiques et statistique, Université Laval Pavillon Vachon, 1045 Avenue de la médecine, Université Laval, Québec, QC, Canada
| | - Nicolas Doyon
- Groupe Interdisciplinaire de Recherche en Éléments Finis (GIREF), Département de mathématiques et statistique, Université Laval Pavillon Vachon, 1045 Avenue de la médecine, Université Laval, Québec, QC, Canada.
| | - Jean Deteix
- Groupe Interdisciplinaire de Recherche en Éléments Finis (GIREF), Département de mathématiques et statistique, Université Laval Pavillon Vachon, 1045 Avenue de la médecine, Université Laval, Québec, QC, Canada
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Wu XQ, Su N, Fei Z, Fei F. Homer signaling pathways as effective therapeutic targets for ischemic and traumatic brain injuries and retinal lesions. Neural Regen Res 2021; 17:1454-1461. [PMID: 34916418 PMCID: PMC8771115 DOI: 10.4103/1673-5374.330588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Ischemic and traumatic insults to the central nervous system account for most serious acute and fatal brain injuries and are usually characterized by primary and secondary damage. Secondary damage presents the greatest challenge for medical staff; however, there are currently few effective therapeutic targets for secondary damage. Homer proteins are postsynaptic scaffolding proteins that have been implicated in ischemic and traumatic insults to the central nervous system. Homer signaling can exert either positive or negative effects during such insults, depending on the specific subtype of Homer protein. Homer 1b/c couples with other proteins to form postsynaptic densities, which form the basis of synaptic transmission, while Homer1a expression can be induced by harmful external factors. Homer 1c is used as a unique biomarker to reveal alterations in synaptic connectivity before and during the early stages of apoptosis in retinal ganglion cells, mediated or affected by extracellular or intracellular signaling or cytoskeletal processes. This review summarizes the structural features, related signaling pathways, and diverse roles of Homer proteins in physiological and pathological processes. Upregulating Homer1a or downregulating Homer1b/c may play a neuroprotective role in secondary brain injuries. Homer also plays an important role in the formation of photoreceptor synapses. These findings confirm the neuroprotective effects of Homer, and support the future design of therapeutic drug targets or gene therapies for ischemic and traumatic brain injuries and retinal disorders based on Homer proteins.
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Affiliation(s)
- Xiu-Quan Wu
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Ning Su
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhou Fei
- Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Fei Fei
- Department of Ophthalmology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi Province, China
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5
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Membrane trafficking and positioning of mGluRs at presynaptic and postsynaptic sites of excitatory synapses. Neuropharmacology 2021; 200:108799. [PMID: 34592242 DOI: 10.1016/j.neuropharm.2021.108799] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 08/31/2021] [Accepted: 09/17/2021] [Indexed: 01/21/2023]
Abstract
The plethora of functions of glutamate in the brain are mediated by the complementary actions of ionotropic and metabotropic glutamate receptors (mGluRs). The ionotropic glutamate receptors carry most of the fast excitatory transmission, while mGluRs modulate transmission on longer timescales by triggering multiple intracellular signaling pathways. As such, mGluRs mediate critical aspects of synaptic transmission and plasticity. Interestingly, at synapses, mGluRs operate at both sides of the cleft, and thus bidirectionally exert the effects of glutamate. At postsynaptic sites, group I mGluRs act to modulate excitability and plasticity. At presynaptic sites, group II and III mGluRs act as auto-receptors, modulating release properties in an activity-dependent manner. Thus, synaptic mGluRs are essential signal integrators that functionally couple presynaptic and postsynaptic mechanisms of transmission and plasticity. Understanding how these receptors reach the membrane and are positioned relative to the presynaptic glutamate release site are therefore important aspects of synapse biology. In this review, we will discuss the currently known mechanisms underlying the trafficking and positioning of mGluRs at and around synapses, and how these mechanisms contribute to synaptic functioning. We will highlight outstanding questions and present an outlook on how recent technological developments will move this exciting research field forward.
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6
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Feghhi T, Hernandez RX, Stawarski M, Thomas CI, Kamasawa N, Lau AWC, Macleod GT. Computational modeling predicts ephemeral acidic microdomains in the glutamatergic synaptic cleft. Biophys J 2021; 120:5575-5591. [PMID: 34774503 DOI: 10.1016/j.bpj.2021.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/21/2021] [Accepted: 11/05/2021] [Indexed: 10/19/2022] Open
Abstract
At chemical synapses, synaptic vesicles release their acidic contents into the cleft, leading to the expectation that the cleft should acidify. However, fluorescent pH probes targeted to the cleft of conventional glutamatergic synapses in both fruit flies and mice reveal cleft alkalinization rather than acidification. Here, using a reaction-diffusion scheme, we modeled pH dynamics at the Drosophila neuromuscular junction as glutamate, ATP, and protons (H+) were released into the cleft. The model incorporates bicarbonate and phosphate buffering systems as well as plasma membrane calcium-ATPase activity and predicts substantial cleft acidification but only for fractions of a millisecond after neurotransmitter release. Thereafter, the cleft rapidly alkalinizes and remains alkaline for over 100 ms because the plasma membrane calcium-ATPase removes H+ from the cleft in exchange for calcium ions from adjacent pre- and postsynaptic compartments, thus recapitulating the empirical data. The extent of synaptic vesicle loading and time course of exocytosis have little influence on the magnitude of acidification. Phosphate but not bicarbonate buffering is effective at suppressing the magnitude and time course of the acid spike, whereas both buffering systems are effective at suppressing cleft alkalinization. The small volume of the cleft levies a powerful influence on the magnitude of alkalinization and its time course. Structural features that open the cleft to adjacent spaces appear to be essential for alleviating the extent of pH transients accompanying neurotransmission.
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Affiliation(s)
- Touhid Feghhi
- Department of Physics, College of Science, Florida Atlantic University, Boca Raton, Florida
| | - Roberto X Hernandez
- Integrative Biology & Neuroscience Graduate Program, Florida Atlantic University, Boca Raton, Florida; International Max Planck Research School for Brain and Behavior, Jupiter, Florida; Jupiter Life Sciences Initiative, Florida Atlantic University, Jupiter, Florida
| | - Michal Stawarski
- Wilkes Honors College, Florida Atlantic University, Jupiter, Florida
| | - Connon I Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute, Jupiter, Florida
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute, Jupiter, Florida
| | - A W C Lau
- Department of Physics, College of Science, Florida Atlantic University, Boca Raton, Florida
| | - Gregory T Macleod
- Jupiter Life Sciences Initiative, Florida Atlantic University, Jupiter, Florida; Wilkes Honors College, Florida Atlantic University, Jupiter, Florida; Brain Institute, Florida Atlantic University, Jupiter, Florida; Institute for Human Health & Disease Intervention, Florida Atlantic University, Jupiter, Florida.
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7
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Savtchenko LP, Zheng K, Rusakov DA. Buffering by Transporters Can Spare Geometric Hindrance in Controlling Glutamate Escape. Front Cell Neurosci 2021; 15:707813. [PMID: 34366791 PMCID: PMC8342858 DOI: 10.3389/fncel.2021.707813] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 06/21/2021] [Indexed: 12/21/2022] Open
Abstract
The surface of astrocyte processes that often surround excitatory synapses is packed with high-affinity glutamate transporters, largely preventing extrasynaptic glutamate escape. The shape and prevalence of perisynaptic astroglia vary among brain regions, in some cases providing a complete isolation of synaptic connections from the surrounding tissue. The perception has been that the geometry of perisynaptic environment is therefore essential to preventing extrasynaptic glutamate escape. To understand to what degree this notion holds, we modelled brain neuropil as a space filled with a scatter of randomly sized, overlapping spheres representing randomly shaped cellular elements and intercellular lumen. Simulating release and diffusion of glutamate molecules inside the interstitial gaps in this medium showed that high-affinity transporters would efficiently constrain extrasynaptic spread of glutamate even when diffusion passages are relatively open. We thus estimate that, in the hippocampal or cerebellar neuropil, the bulk of glutamate released by a synaptic vesicle is rapidly bound by transporters (or high-affinity target receptors) mainly in close proximity of the synaptic cleft, whether or not certain physiological or pathological events change local tissue geometry.
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Affiliation(s)
- Leonid P. Savtchenko
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | | | - Dmitri A. Rusakov
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
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8
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Tricot A, Sokolov IM, Holcman D. Modeling the voltage distribution in a non-locally but globally electroneutral confined electrolyte medium: applications for nanophysiology. J Math Biol 2021; 82:65. [PMID: 34057627 DOI: 10.1007/s00285-021-01618-x] [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: 10/10/2020] [Revised: 03/14/2021] [Accepted: 05/17/2021] [Indexed: 11/25/2022]
Abstract
The distribution of voltage in sub-micron cellular domains remains poorly understood. In neurons, the voltage results from the difference in ionic concentrations which are continuously maintained by pumps and exchangers. However, it not clear how electro-neutrality could be maintained by an excess of fast moving positive ions that should be counter balanced by slow diffusing negatively charged proteins. Using the theory of electro-diffusion, we study here the voltage distribution in a generic domain, which consists of two concentric disks (resp. ball) in two (resp. three) dimensions, where a negative charge is fixed in the inner domain. When global but not local electro-neutrality is maintained, we solve the Poisson-Nernst-Planck equation both analytically and numerically in dimension 1 (flat) and 2 (cylindrical) and found that the voltage changes considerably on a spatial scale which is much larger than the Debye screening length, which assumes electro-neutrality. The present result suggests that long-range voltage drop changes are expected in neuronal microcompartments, probably relevant to explain the activation of far away voltage-gated channels located on the surface membrane.
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Affiliation(s)
- A Tricot
- Data Modeling, Computational Biology and Predictive Medicine, Ecole Normale Supérieure PSL, 46 rue d'Ulm, 75005, Paris, France
| | - I M Sokolov
- Institute of Physics and IRIS Adlershof, Humboldt University Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - D Holcman
- Data Modeling, Computational Biology and Predictive Medicine, Ecole Normale Supérieure PSL, 46 rue d'Ulm, 75005, Paris, France.
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9
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Petit-Pedrol M, Groc L. Regulation of membrane NMDA receptors by dynamics and protein interactions. J Cell Biol 2021; 220:211609. [PMID: 33337489 PMCID: PMC7754687 DOI: 10.1083/jcb.202006101] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 12/16/2022] Open
Abstract
Understanding neurotransmitter system crosstalk in the brain is a major challenge in neurobiology. Several intracellular and genomic cascades have been identified in this crosstalk. However, the discovery that neurotransmitter receptors are highly diffusive in the plasma membrane of neurons, where they form heterocomplexes with other proteins, has profoundly changed our view of neurotransmitter signaling. Here, we review new insights into neurotransmitter crosstalk at the plasma membrane. We focus on the membrane organization and interactome of the ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR) that plays a central role in excitatory synaptic and network physiology and is involved in the etiology of several major neuropsychiatric disorders. The nanoscale organization and dynamics of NMDAR is a key regulatory process for glutamate synapse transmission, plasticity, and crosstalk with other neurotransmitter systems, such as the monoaminergic ones. The plasma membrane appears to be a prime regulatory compartment for spatial and temporal crosstalk between neurotransmitter systems in the healthy and diseased brain. Understanding the molecular mechanisms regulating membrane neurotransmitter receptor crosstalk will likely open research avenues for innovative therapeutical strategies.
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Affiliation(s)
- Mar Petit-Pedrol
- Université de Bordeaux, Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, Unité Mixte de Recherche 5297, Bordeaux, France
| | - Laurent Groc
- Université de Bordeaux, Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, Unité Mixte de Recherche 5297, Bordeaux, France
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10
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Savtchenko LP, Zheng K, Rusakov DA. Conductance of porous media depends on external electric fields. Biophys J 2021; 120:1431-1442. [PMID: 33609495 PMCID: PMC8105728 DOI: 10.1016/j.bpj.2021.02.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 01/12/2021] [Accepted: 02/01/2021] [Indexed: 11/28/2022] Open
Abstract
In obstacle-filled media, such as extracellular or intracellular lumen of brain tissue, effective ion-diffusion permeability is a key determinant of electrogenic reactions. Although this diffusion permeability is thought to depend entirely on structural features of the medium, such as porosity and tortuosity, brain tissue shows prominent nonohmic properties, the origins of which remain poorly understood. Here, we explore Monte Carlo simulations of ion diffusion in a space filled with overlapping spheres to predict that diffusion permeability of such media decreases with stronger external electric fields. This dependence increases with lower medium porosity while decreasing with radial (two-dimensional or three-dimensional) compared with homogenous (one-dimensional) fields. We test our predictions empirically in an electrolyte chamber filled with microscopic glass spheres and find good correspondence with our predictions. A theoretical insight relates this phenomenon to a disproportionately increased dwell time of diffusing ions at potential barriers (or traps) representing geometric obstacles when the field strength increases. The dependence of medium ion-diffusion permeability on electric field could be important for understanding conductivity properties of porous materials, in particular for the accurate interpretation of electric activity recordings in brain tissue.
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Affiliation(s)
- Leonid P Savtchenko
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.
| | - Kaiyu Zheng
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.
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11
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So LY, Miller JE. Social context-dependent singing alters molecular markers of synaptic plasticity signaling in finch basal ganglia Area X. Behav Brain Res 2020; 398:112955. [PMID: 33031871 DOI: 10.1016/j.bbr.2020.112955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/14/2020] [Accepted: 09/30/2020] [Indexed: 12/23/2022]
Abstract
Vocal communication is a crucial skill required throughout life. However, there is a critical gap in our understanding of the underlying molecular brain mechanisms, thereby motivating our use of the zebra finch songbird model. Adult male zebra finches show differences in neural activity patterns in song-dedicated brain nuclei when they sing in two distinct social contexts: a male singing by himself (undirected, UD) and a male singing to a female (female-directed, FD). In our prior work, we showed that in song-dedicated basal ganglia Area X, protein levels of a N-methyl-D-aspartate receptor subtype 2B (NMDAR2B) increased with more UD song and decreased with more FD song. We hypothesized that molecules downstream of this receptor would show differential protein expression levels in Area X between UD and FD song. Specifically, we investigated calcium/calmodulin dependent protein kinase II beta (CaMKIIB), homer scaffold protein 1 (HOMER1), serine/threonine protein kinase (Akt), and mechanistic target of rapamycin kinase (mTOR) following singing and non-singing states in Area X. We show relationships between social context and protein levels. HOMER1 protein levels decreased with time spent singing FD song, and mTOR protein levels decreased with the amount of and time spent singing FD song. For both HOMER1 and mTOR, there were no differences with the amount of UD song. With time spent singing UD, CaMKIIB protein levels trended in a U-shaped curve whereas Akt protein levels trended down. Both molecules showed no change with FD song. Our results support differential involvement of molecules in synaptic plasticity pathways between UD and FD song behaviors.
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Affiliation(s)
- Lisa Y So
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Gould-Simpson Building, Tucson, AZ, 85721, United States; Department of Neuroscience, University of Arizona, Gould-Simpson Building, Tucson, AZ, 85721, United States
| | - Julie E Miller
- Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Gould-Simpson Building, Tucson, AZ, 85721, United States; Department of Neuroscience, University of Arizona, Gould-Simpson Building, Tucson, AZ, 85721, United States; Department of Speech, Language, and Hearing Sciences, University of Arizona, Speech, Language, and Hearing Sciences Building, Tucson, AZ, 85721, United States.
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12
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Sylantyev S, Savtchenko LP, O'Neill N, Rusakov DA. Extracellular GABA waves regulate coincidence detection in excitatory circuits. J Physiol 2020; 598:4047-4062. [PMID: 32667048 PMCID: PMC8432164 DOI: 10.1113/jp279744] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 07/09/2020] [Indexed: 11/23/2022] Open
Abstract
KEY POINTS Rapid changes in neuronal network activity trigger widespread waves of extracellular GABA in hippocampal neuropil. Elevations of extracellular GABA narrow the coincidence detection window for excitatory inputs to CA1 pyramidal cells. GABA transporters control the effect of extracellular GABA on coincidence detection. Small changes in the kinetics of dendritic excitatory currents amplify when reaching the soma. ABSTRACT Coincidence detection of excitatory inputs by principal neurons underpins the rules of signal integration and Hebbian plasticity in the brain. In the hippocampal circuitry, detection fidelity is thought to depend on the GABAergic synaptic input through a feedforward inhibitory circuit also involving the hyperpolarisation-activated Ih current. However, afferent connections often bypass feedforward circuitry, suggesting that a different GABAergic mechanism might control coincidence detection in such cases. To test whether fluctuations in the extracellular GABA concentration [GABA] could play a regulatory role here, we use a GABA 'sniffer' patch in acute hippocampal slices of the rat and document strong dependence of [GABA] on network activity. We find that blocking GABAergic signalling strongly widens the coincidence detection window of direct excitatory inputs to pyramidal cells whereas increasing [GABA] through GABA uptake blockade shortens it. The underlying mechanism involves membrane-shunting tonic GABAA receptor current; it does not have to rely on Ih but depends strongly on the neuronal GABA transporter GAT-1. We use dendrite-soma dual patch-clamp recordings to show that the strong effect of membrane shunting on coincidence detection relies on nonlinear amplification of changes in the decay of dendritic synaptic currents when they reach the soma. Our results suggest that, by dynamically regulating extracellular GABA, brain network activity can optimise signal integration rules in local excitatory circuits.
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Affiliation(s)
- Sergiy Sylantyev
- Rowett InstituteUniversity of AberdeenAshgrove Rd. WestAberdeenAB25 2ZDUK
- UCL Queen Square Institute of NeurologyUniversity College LondonQueen SquareLondonWC1N 3BGUK
| | - Leonid P. Savtchenko
- UCL Queen Square Institute of NeurologyUniversity College LondonQueen SquareLondonWC1N 3BGUK
| | - Nathanael O'Neill
- Centre for Clinical Brain SciencesUniversity of Edinburgh49 Little France CrescentEdinburghEH16 4SBUK
| | - Dmitri A. Rusakov
- UCL Queen Square Institute of NeurologyUniversity College LondonQueen SquareLondonWC1N 3BGUK
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13
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Bao J, Graupner M, Astorga G, Collin T, Jalil A, Indriati DW, Bradley J, Shigemoto R, Llano I. Synergism of type 1 metabotropic and ionotropic glutamate receptors in cerebellar molecular layer interneurons in vivo. eLife 2020; 9:56839. [PMID: 32401196 PMCID: PMC7220378 DOI: 10.7554/elife.56839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/27/2020] [Indexed: 11/16/2022] Open
Abstract
Type 1 metabotropic glutamate receptors (mGluR1s) are key elements in neuronal signaling. While their function is well documented in slices, requirements for their activation in vivo are poorly understood. We examine this question in adult mice in vivo using 2-photon imaging of cerebellar molecular layer interneurons (MLIs) expressing GCaMP. In anesthetized mice, parallel fiber activation evokes beam-like Cai rises in postsynaptic MLIs which depend on co-activation of mGluR1s and ionotropic glutamate receptors (iGluRs). In awake mice, blocking mGluR1 decreases Cai rises associated with locomotion. In vitro studies and freeze-fracture electron microscopy show that the iGluR-mGluR1 interaction is synergistic and favored by close association of the two classes of receptors. Altogether our results suggest that mGluR1s, acting in synergy with iGluRs, potently contribute to processing cerebellar neuronal signaling under physiological conditions.
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Affiliation(s)
- Jin Bao
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,The Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences; Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Michael Graupner
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Guadalupe Astorga
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Thibault Collin
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Abdelali Jalil
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Dwi Wahyu Indriati
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan
| | - Jonathan Bradley
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France.,Institut de Biologie de l'Ecole Normale Superieure (IBENS), Ecole Normale Superieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, The Graduate University for Advanced Studies (Sokendai), Okazaki, Japan.,IST Austria, Klosterneuburg, Austria
| | - Isabel Llano
- Université de Paris, CNRS, SPPIN - Saints-Pères Paris Institute for the Neurosciences, Paris, France
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14
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Electrodiffusion models of synaptic potentials in dendritic spines. J Comput Neurosci 2019; 47:77-89. [PMID: 31410632 DOI: 10.1007/s10827-019-00725-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/17/2022]
Abstract
The biophysical properties of dendritic spines play a critical role in neuronal integration but are still poorly understood, due to experimental difficulties in accessing them. Spine biophysics has been traditionally explored using theoretical models based on cable theory. However, cable theory generally assumes that concentration changes associated with ionic currents are negligible and, therefore, ignores electrodiffusion, i.e. the interaction between electric fields and ionic diffusion. This assumption, while true for large neuronal compartments, could be incorrect when applied to femto-liter size structures such as dendritic spines. To extend cable theory and explore electrodiffusion effects, we use here the Poisson (P) and Nernst-Planck (NP) equations, which relate electric field to charge and Fick's law of diffusion, to model ion concentration dynamics in spines receiving excitatory synaptic potentials (EPSPs). We use experimentally measured voltage transients from spines with nanoelectrodes to explore these dynamics with realistic parameters. We find that (i) passive diffusion and electrodiffusion jointly affect the dynamics of spine EPSPs; (ii) spine geometry plays a key role in shaping EPSPs; and, (iii) the spine-neck resistance dynamically decreases during EPSPs, leading to short-term synaptic facilitation. Our formulation, which complements and extends cable theory, can be easily adapted to model ionic biophysics in other nanoscale bio-compartments.
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15
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Cartailler J, Holcman D. Electrical transient laws in neuronal microdomains based on electro-diffusion. Phys Chem Chem Phys 2019; 20:21062-21067. [PMID: 30074044 DOI: 10.1039/c8cp02593b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The current-voltage (I-V) conversion characterizes the physiology of cellular microdomains and reflects cellular communication, excitability, and electrical transduction. Yet deriving such I-V laws remains a major challenge in most cellular microdomains due to their small sizes and the difficulty in assessing voltage with high nanometer precision. We present here novel analytical relations derived for different numbers of ionic species inside neuronal micro/nano-domains, such as dendritic spines. When a steady-state current is injected, we find a large deviation from the classical Ohm's law, showing that the spine neck resistance is insufficient to characterize electrical properties. For a constricted spine neck, modeled by a hyperboloid, we obtain a new I-V law that illustrates the consequences of narrow passages on electrical conduction. Finally, during a fast current transient, the local voltage is modulated by the distance between activated voltage-gated channels. To conclude, electro-diffusion laws can now be used to interpret voltage distribution in neuronal microdomains.
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Affiliation(s)
- J Cartailler
- Group of Computational Biology and Applied Mathematics, Ecole Normale Supérieure, 75005 Paris, France.
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16
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Clifton NE, Trent S, Thomas KL, Hall J. Regulation and Function of Activity-Dependent Homer in Synaptic Plasticity. MOLECULAR NEUROPSYCHIATRY 2019; 5:147-161. [PMID: 31312636 DOI: 10.1159/000500267] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/09/2019] [Indexed: 12/22/2022]
Abstract
Alterations in synaptic signaling and plasticity occur during the refinement of neural circuits over the course of development and the adult processes of learning and memory. Synaptic plasticity requires the rearrangement of protein complexes in the postsynaptic density (PSD), trafficking of receptors and ion channels and the synthesis of new proteins. Activity-induced short Homer proteins, Homer1a and Ania-3, are recruited to active excitatory synapses, where they act as dominant negative regulators of constitutively expressed, longer Homer isoforms. The expression of Homer1a and Ania-3 initiates critical processes of PSD remodeling, the modulation of glutamate receptor-mediated functions, and the regulation of calcium signaling. Together, available data support the view that Homer1a and Ania-3 are responsible for the selective, transient destabilization of postsynaptic signaling complexes to facilitate plasticity of the excitatory synapse. The interruption of activity-dependent Homer proteins disrupts disease-relevant processes and leads to memory impairments, reflecting their likely contribution to neurological disorders.
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Affiliation(s)
- Nicholas E Clifton
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom.,MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Simon Trent
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom
| | - Kerrie L Thomas
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom.,School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, Cardiff University, Cardiff, United Kingdom.,MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
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17
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Rusakov DA, Savtchenko LP. Extreme statistics may govern avalanche-type biological reactions: Comment on "Redundancy principle and the role of extreme statistics in molecular and cellular biology" by Z. Schuss, K. Basnayake, D. Holcman. Phys Life Rev 2019; 28:85-87. [PMID: 30819590 DOI: 10.1016/j.plrev.2019.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 02/18/2019] [Indexed: 11/22/2022]
Affiliation(s)
- Dmitri A Rusakov
- Queen Square UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, United Kingdom.
| | - Leonid P Savtchenko
- Queen Square UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, United Kingdom
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18
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O'Neill N, Sylantyev S. Glutamate Receptor Probing with Rapid Application and Solution Exchange (RASE). Methods Mol Biol 2019; 1941:65-78. [PMID: 30707428 DOI: 10.1007/978-1-4939-9077-1_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Probing of glutamate receptors at sub-millisecond time scale is a key element needed for understanding of their response kinetics, neural signal transduction, and, in a wider context, intercellular cross talk. One of the classical techniques used to obtain this type of data in electrophysiology is placing a recording pipette in front of a double-barrel solution application pipette, which provides a rapid switch between two solutions. Here we describe a modification of this classical technique, which utilizes a solution application pipette with several loading capillaries. Such a system is capable of replacing multiple application solutions within 7-12 s time intervals. This modified protocol enables ultrafast application of several solutions at the same set of receptors, thus allowing powerful paired-sample statistical approaches. In addition, the same experimental equipment fabricated for the ultra-resolution probing of receptor kinetics can also be applied in several other types of electrophysiological experiments.
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19
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O'Neill N, McLaughlin C, Komiyama N, Sylantyev S. Biphasic Modulation of NMDA Receptor Function by Metabotropic Glutamate Receptors. J Neurosci 2018; 38:9840-9855. [PMID: 30282730 PMCID: PMC6234301 DOI: 10.1523/jneurosci.1000-18.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 09/02/2018] [Accepted: 09/09/2018] [Indexed: 01/14/2023] Open
Abstract
A recently reported rapid potentiation of NMDA receptors by Group I metabotropic glutamate receptors (mGluRIs) via a Homer protein link is distinct from the classical, relatively slow inhibitory G-protein-associated signaling triggered by mGluRI activation. The relationship between these two mechanisms remains unknown. Here, we focused on the mGluRI-dependent modulation of NMDAR response in hippocampal dentate gyrus granule cells and cerebellar granule cells of C57BL6-J mice and found that these two contrasting mechanisms overlap competitively on the time scale from hundreds of milliseconds to seconds, with the net effect depending on the cell type. At a shorter time interval (units of millisecond), the Homer-mediated signal from mGluRIs prevails, causing upregulation of NMDAR function, in both dentate gyrus granule cells and cerebellar granule cells. Our results shed light on the possible mechanisms of anti-schizophrenia drugs that disrupt Homer-containing protein link.SIGNIFICANCE STATEMENT Here we study modulation of NMDA receptors triggered by activation of metabotropic glutamate receptors Group I via two distinct pathways: classical G-protein signaling system and newly discovered high-speed modulatory mechanism associated with Homer-protein-containing direct molecular link. We found that these two contrasting mechanisms overlap competitively on the time scale from hundreds of milliseconds to seconds, with the net effect depending on the cell type. We have also found that both crosstalk mechanisms cause significant changes in synaptic strength and plasticity. Our results resolve an apparent discrepancy between earlier studies that demonstrated contradictive effects of Homer-containing protein link disruption on NMDA receptor signaling. On top of that, our data provide a plausible explanation for unclear action mechanisms of anti-schizophrenia drugs.
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Affiliation(s)
- Nathanael O'Neill
- Centre for Clinical Brain Sciences, University of Edinburgh, EH16 4SB, Edinburgh, United Kingdom
| | - Catherine McLaughlin
- Centre for Clinical Brain Sciences, University of Edinburgh, EH16 4SB, Edinburgh, United Kingdom
| | - Noboru Komiyama
- Centre for Clinical Brain Sciences, University of Edinburgh, EH16 4SB, Edinburgh, United Kingdom
- Centre for Neuroregeneration, University of Edinburgh, EH16 4SB, Edinburgh, United Kingdom, and
| | - Sergiy Sylantyev
- Centre for Clinical Brain Sciences, University of Edinburgh, EH16 4SB, Edinburgh, United Kingdom,
- Department for Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
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20
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Convergent Metabotropic Signaling Pathways Inhibit SK Channels to Promote Synaptic Plasticity in the Hippocampus. J Neurosci 2018; 38:9252-9262. [PMID: 30242046 PMCID: PMC6199408 DOI: 10.1523/jneurosci.1160-18.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/16/2018] [Accepted: 08/09/2018] [Indexed: 12/27/2022] Open
Abstract
Hebbian synaptic plasticity at hippocampal Schaffer collateral synapses is tightly regulated by postsynaptic small conductance (SK) channels that restrict NMDA receptor activity. SK channels are themselves modulated by G-protein-coupled signaling pathways, but it is not clear under what conditions these are activated to enable synaptic plasticity. Here, we show that muscarinic M1 receptor (M1R) and type 1 metabotropic glutamate receptor (mGluR1) signaling pathways, which are known to inhibit SK channels and thereby disinhibit NMDA receptors, converge to facilitate spine calcium transients during the induction of long-term potentiation (LTP) at hippocampal Schaffer collateral synapses onto CA1 pyramidal neurons of male rats. Furthermore, mGluR1 activation is required for LTP induced by reactivated place-cell firing patterns that occur in sharp-wave ripple events during rest or sleep. In contrast, M1R activation is required for LTP induced by place-cell firing patterns during exploration. Thus, we describe a common mechanism that enables synaptic plasticity during both encoding and consolidation of memories within hippocampal circuits.SIGNIFICANCE STATEMENT Memory ensembles in the hippocampus are formed during active exploration and consolidated during rest or sleep. These two distinct phases each require strengthening of synaptic connections by long-term potentiation (LTP). The neuronal activity patterns in each phase are very different, which makes it hard to map generalized rules for LTP induction onto both formation and consolidation phases. In this study, we show that inhibition of postsynaptic SK channels is a common necessary feature of LTP induction and that SK channel inhibition is achieved by separate but convergent metabotropic signaling pathways. Thus, we reveal a common mechanism for enabling LTP under distinct behavioral conditions.
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21
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Sensitivity analysis of the Poisson Nernst-Planck equations: a finite element approximation for the sensitive analysis of an electrodiffusion model. J Math Biol 2018; 78:21-56. [PMID: 30187223 DOI: 10.1007/s00285-018-1266-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 04/07/2018] [Indexed: 11/27/2022]
Abstract
Biological structures exhibiting electric potential fluctuations such as neuron and neural structures with complex geometries are modelled using an electrodiffusion or Poisson Nernst-Planck system of equations. These structures typically depend upon several parameters displaying a large degree of variation or that cannot be precisely inferred experimentally. It is crucial to understand how the mathematical model (and resulting simulations) depend on specific values of these parameters. Here we develop a rigorous approach based on the sensitivity equation for the electrodiffusion model. To illustrate the proposed methodology, we investigate the sensitivity of the electrical response of a node of Ranvier with respect to ionic diffusion coefficients and the membrane dielectric permittivity.
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22
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Cartailler J, Kwon T, Yuste R, Holcman D. Deconvolution of Voltage Sensor Time Series and Electro-diffusion Modeling Reveal the Role of Spine Geometry in Controlling Synaptic Strength. Neuron 2018; 97:1126-1136.e10. [PMID: 29429935 DOI: 10.1016/j.neuron.2018.01.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/09/2017] [Accepted: 01/12/2018] [Indexed: 01/03/2023]
Abstract
Most synaptic excitatory connections are made on dendritic spines. But how the voltage in spines is modulated by its geometry remains unclear. To investigate the electrical properties of spines, we combine voltage imaging data with electro-diffusion modeling. We first present a temporal deconvolution procedure for the genetically encoded voltage sensor expressed in hippocampal cultured neurons and then use electro-diffusion theory to compute the electric field and the current-voltage conversion. We extract a range for the neck resistances of 〈R〉=100±35MΩ. When a significant current is injected in a spine, the neck resistance can be inversely proportional to its radius, but not to the radius square, as predicted by Ohm's law. We conclude that the postsynaptic voltage cannot only be modulated by changing the number of receptors, but also by the spine geometry. Thus, spine morphology could be a key component in determining synaptic transduction and plasticity.
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Affiliation(s)
- Jerome Cartailler
- Institut de Biologie de l'École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France
| | - Taekyung Kwon
- Neurotechnology Center, Depts. Biological Sciences and Neuroscience, Columbia University, New York, NY 10027, USA
| | - Rafael Yuste
- Neurotechnology Center, Depts. Biological Sciences and Neuroscience, Columbia University, New York, NY 10027, USA
| | - David Holcman
- Institut de Biologie de l'École Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France.
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23
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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24
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 916] [Impact Index Per Article: 152.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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25
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Hippocampal Regulation of Postsynaptic Density Homer1 by Associative Learning. Neural Plast 2017; 2017:5959182. [PMID: 29238619 PMCID: PMC5697134 DOI: 10.1155/2017/5959182] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/18/2017] [Accepted: 10/10/2017] [Indexed: 11/18/2022] Open
Abstract
Genes involved in synaptic plasticity, particularly genes encoding postsynaptic density proteins, have been recurrently linked to psychiatric disorders including schizophrenia and autism. Postsynaptic density Homer1 proteins contribute to synaptic plasticity through the competing actions of short and long isoforms. The activity-induced expression of short Homer1 isoforms, Homer1a and Ania-3, is thought to be related to processes of learning and memory. However, the precise regulation of Homer1a and Ania-3 with different components of learning has not been investigated. Here, we used in situ hybridization to quantify short and long Homer1 expression in the hippocampus following consolidation, retrieval, and extinction of associative fear memory, using contextual fear conditioning in rats. Homer1a and Ania-3, but not long Homer1, were regulated by contextual fear learning or novelty detection, although their precise patterns of expression in hippocampal subregions were dependent on the isoform. We also show for the first time that the two short Homer1 isoforms are regulated after the retrieval and extinction of contextual fear memory, albeit with distinct temporal and spatial profiles. These findings support a role of activity-induced Homer1 isoforms in learning and memory processes in discrete hippocampal subregions and suggest that Homer1a and Ania-3 may play separable roles in synaptic plasticity.
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26
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Abstract
The emerging technological revolution in genetically encoded molecular sensors and super-resolution imaging provides neuroscientists with a pass to the real-time nano-world. On this small scale, however, classical principles of electrophysiology do not always apply. This is in large part because the nanoscopic heterogeneities in ionic concentrations and the local electric fields associated with individual ions and their movement can no longer be ignored. Here, we review basic principles of molecular electrodiffusion in the cellular environment of organized brain tissue. We argue that accurate interpretation of physiological observations on the nanoscale requires a better understanding of the underlying electrodiffusion phenomena.
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27
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Lu HW, Balmer TS, Romero GE, Trussell LO. Slow AMPAR Synaptic Transmission Is Determined by Stargazin and Glutamate Transporters. Neuron 2017; 96:73-80.e4. [PMID: 28919175 DOI: 10.1016/j.neuron.2017.08.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 07/25/2017] [Accepted: 08/28/2017] [Indexed: 01/23/2023]
Abstract
AMPARs mediate the briefest synaptic currents in the brain by virtue of their rapid gating kinetics. However, at the mossy fiber-to-unipolar brush cell synapse in the cerebellum, AMPAR-mediated EPSCs last for hundreds of milliseconds, and it has been proposed that this time course reflects slow diffusion from a complex synaptic space. We show that upon release of glutamate, synaptic AMPARs were desensitized by transmitter by >90%. As glutamate levels subsequently fell, recovery of transmission occurred due to the presence of the AMPAR accessory protein stargazin that enhances the AMPAR response to low levels of transmitter. This gradual increase in receptor activity following desensitization accounted for the majority of synaptic transmission at this synapse. Moreover, the amplitude, duration, and shape of the synaptic response was tightly controlled by plasma membrane glutamate transporters, indicating that clearance of synaptic glutamate during the slow EPSC is dictated by an uptake process.
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Affiliation(s)
- Hsin-Wei Lu
- Neuroscience Graduate Program, Oregon Health and Science University, Portland, OR, USA
| | - Timothy S Balmer
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Gabriel E Romero
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA
| | - Laurence O Trussell
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, OR, USA.
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28
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Cartailler J, Schuss Z, Holcman D. Electrostatics of non-neutral biological microdomains. Sci Rep 2017; 7:11269. [PMID: 28900187 PMCID: PMC5595851 DOI: 10.1038/s41598-017-11590-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 08/24/2017] [Indexed: 11/09/2022] Open
Abstract
Voltage and charge distributions in cellular microdomains regulate communications, excitability, and signal transduction. We report here new electrical laws in a biological cell, which follow from a nonlinear electro-diffusion model. These newly discovered laws derive from the geometrical cell-membrane properties, such as membrane curvature, volume, and surface area. The electro-diffusion laws can now be used to predict and interpret voltage distribution in cellular microdomains such as synapses, dendritic spine, cilia and more.
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Affiliation(s)
- J Cartailler
- Ecole Normale Supérieure, Applied Math and Computational Biology, IBENS 46 rue d'Ulm, 75005, Paris, France
| | - Z Schuss
- Department of Mathematics, Tel-Aviv University, Tel-Aviv, 69978, Israel
| | - D Holcman
- Ecole Normale Supérieure, Applied Math and Computational Biology, IBENS 46 rue d'Ulm, 75005, Paris, France. .,Mathematical Institute, University of Oxford, Oxford, OX2 6GG, United Kingdom.
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29
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Cui P, Li XY, Zhao Y, Li Q, Gao F, Li LZ, Yin N, Sun XH, Wang Z. Activation of dopamine D1 receptors enhances the temporal summation and excitability of rat retinal ganglion cells. Neuroscience 2017; 355:71-83. [DOI: 10.1016/j.neuroscience.2017.04.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/24/2017] [Accepted: 04/30/2017] [Indexed: 01/11/2023]
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30
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Aleksin SG, Zheng K, Rusakov DA, Savtchenko LP. ARACHNE: A neural-neuroglial network builder with remotely controlled parallel computing. PLoS Comput Biol 2017; 13:e1005467. [PMID: 28362877 PMCID: PMC5393895 DOI: 10.1371/journal.pcbi.1005467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 04/17/2017] [Accepted: 03/20/2017] [Indexed: 11/30/2022] Open
Abstract
Creating and running realistic models of neural networks has hitherto been a task for computing professionals rather than experimental neuroscientists. This is mainly because such networks usually engage substantial computational resources, the handling of which requires specific programing skills. Here we put forward a newly developed simulation environment ARACHNE: it enables an investigator to build and explore cellular networks of arbitrary biophysical and architectural complexity using the logic of NEURON and a simple interface on a local computer or a mobile device. The interface can control, through the internet, an optimized computational kernel installed on a remote computer cluster. ARACHNE can combine neuronal (wired) and astroglial (extracellular volume-transmission driven) network types and adopt realistic cell models from the NEURON library. The program and documentation (current version) are available at GitHub repository https://github.com/LeonidSavtchenko/Arachne under the MIT License (MIT).
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Affiliation(s)
- Sergey G. Aleksin
- AMC Bridge LLC, Waltham MA, United States of America and Dnipro, Ukraine
| | - Kaiyu Zheng
- UCL Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
| | - Dmitri A. Rusakov
- UCL Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
- * E-mail: (LPS); (DAR)
| | - Leonid P. Savtchenko
- UCL Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
- Institute of Neuroscience, University of Nizhny Novgorod, Nizhny Novgorod, Russia
- * E-mail: (LPS); (DAR)
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31
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Sibarov DA, Abushik PA, Giniatullin R, Antonov SM. GluN2A Subunit-Containing NMDA Receptors Are the Preferential Neuronal Targets of Homocysteine. Front Cell Neurosci 2016; 10:246. [PMID: 27847466 PMCID: PMC5088185 DOI: 10.3389/fncel.2016.00246] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 10/07/2016] [Indexed: 12/30/2022] Open
Abstract
Homocysteine (HCY) is an endogenous redox active amino acid, best known as contributor to various neurodegenerative disorders. Although it is known that HCY can activate NMDA receptors (NMDARs), the mechanisms of its action on receptors composed of different NMDA receptor subunits remains almost unknown. In this study, using imaging and patch clamp technique in cultured cortical neurons and heterologous expression in HEK293T cells we tested the agonist activity of HCY on NMDARs composed of GluN1 and GluN2A subunits (GluN1/2A receptors) and GluN1 and GluN2B subunits (GluN1/2B receptors). We demonstrate that the time courses of Ca2+ transients and membrane currents activated by HCY and NMDA in cortical neurons are drastically different. Application of HCY to cortical neurons induced responses, which in contrast to currents induced by NMDA (both in the presence of glycine) considerably decreased to steady state of small amplitude. In contrast to NMDA, HCY-activated currents at steady state were resistant to the selective GluN2B subunit inhibitor ifenprodil. In calcium-free external solution the decrease of NMDA evoked currents was abolished, suggesting the Ca2+-dependent NMDAR desensitization. Under these conditions HCY evoked currents still declined almost to the baseline suggesting Ca2+-independent desensitization. In HEK293T cells HCY activated NMDARs of GluN1/2A and GluN1/2B subunit compositions with EC50s of 9.7 ± 1.8 and 61.8 ± 8.9 μM, respectively. Recombinant GluN1/2A receptors, however, did not desensitize by HCY, whereas GluN1/2B receptors were almost fully desensitized by HCY. Thus, HCY is a high affinity agonist of NMDARs preferring the GluN1/2A subunit composition. Our data suggest that HCY induced native NMDAR currents in neurons are mainly mediated by the "synaptic type" GluN1/2A NMDARs. This implies that in hyperhomocysteinemia, a disorder with enlarged level of HCY in plasma, HCY may persistently contribute to post-synaptic responses mediated by GluN2A-containing NMDA receptors. On the other hand, HCY toxicity may be limited by desensitization typical for HCY-induced activation of GluN2B-containing extrasynaptic receptors. Our findings, therefore, provide an evidence for the physiological relevance of endogenous HCY, which may represent an effective endogenous modulator of the central excitatory neurotransmission.
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Affiliation(s)
- Dmitry A Sibarov
- Laboratory of Comparative Neurophysiology, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences Saint-Petersburg, Russia
| | - Polina A Abushik
- Laboratory of Comparative Neurophysiology, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences Saint-Petersburg, Russia
| | - Rashid Giniatullin
- Department of Neurobiology, University of Eastern FinlandKuopio, Finland; Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
| | - Sergei M Antonov
- Laboratory of Comparative Neurophysiology, Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences Saint-Petersburg, Russia
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32
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Zheng K, Rusakov DA. Efficient integration of synaptic events by NMDA receptors in three-dimensional neuropil. Biophys J 2016; 108:2457-2464. [PMID: 25992724 PMCID: PMC4456998 DOI: 10.1016/j.bpj.2015.04.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 04/04/2015] [Accepted: 04/09/2015] [Indexed: 01/15/2023] Open
Abstract
Sustained activation of NMDA receptors (NMDARs) plays an important role in controlling activity of neural circuits in the brain. However, whether this activation reflects the ambient level of excitatory neurotransmitter glutamate in brain tissue or whether it depends mainly on local synaptic discharges remains poorly understood. To shed light on the underlying biophysics here we developed and explored a detailed Monte Carlo model of a realistic three-dimensional neuropil fragment containing 54 excitatory synapses. To trace individual molecules and their individual receptor interactions on this scale, we have designed and implemented a dedicated computer cluster and the appropriate software environment. Our simulations have suggested that sparse synaptic discharges are 20-30 times more efficient than nonsynaptic (stationary, leaky) supply of glutamate in controlling sustained NMDAR occupancy in the brain. This mechanism could explain how the brain circuits provide substantial background activation of NMDARs while maintaining a negligible ambient glutamate level in the extracellular space. Thus the background NMDAR occupancy, rather than the background glutamate level, is likely to reflect the ongoing activity in local excitatory networks.
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Affiliation(s)
- Kaiyu Zheng
- UCL Institute of Neurology, University College London, Queen Square, London, United Kingdom.
| | - Dmitri A Rusakov
- UCL Institute of Neurology, University College London, Queen Square, London, United Kingdom.
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33
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Tigaret CM, Olivo V, Sadowski JHLP, Ashby MC, Mellor JR. Coordinated activation of distinct Ca(2+) sources and metabotropic glutamate receptors encodes Hebbian synaptic plasticity. Nat Commun 2016; 7:10289. [PMID: 26758963 PMCID: PMC4735496 DOI: 10.1038/ncomms10289] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/26/2015] [Indexed: 01/10/2023] Open
Abstract
At glutamatergic synapses, induction of associative synaptic plasticity requires time-correlated presynaptic and postsynaptic spikes to activate postsynaptic NMDA receptors (NMDARs). The magnitudes of the ensuing Ca2+ transients within dendritic spines are thought to determine the amplitude and direction of synaptic change. In contrast, we show that at mature hippocampal Schaffer collateral synapses the magnitudes of Ca2+ transients during plasticity induction do not match this rule. Indeed, LTP induced by time-correlated pre- and postsynaptic spikes instead requires the sequential activation of NMDARs followed by voltage-sensitive Ca2+ channels within dendritic spines. Furthermore, LTP requires inhibition of SK channels by mGluR1, which removes a negative feedback loop that constitutively regulates NMDARs. Therefore, rather than being controlled simply by the magnitude of the postsynaptic calcium rise, LTP induction requires the coordinated activation of distinct sources of Ca2+ and mGluR1-dependent facilitation of NMDAR function. During STDP, the magnitude of postsynaptic Ca2+ transients is hypothesized to determine the strength of synaptic plasticity. Here, the authors find that STDP in mature hippocampal synapses does not obey this rule but instead relies on the coordinated activation of NMDARs and VGCCs and their regulation by mGluRs and SK channels.
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Affiliation(s)
- Cezar M Tigaret
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Valeria Olivo
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Josef H L P Sadowski
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Michael C Ashby
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Jack R Mellor
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol BS8 1TD, UK
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34
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Heller JP, Rusakov DA. Morphological plasticity of astroglia: Understanding synaptic microenvironment. Glia 2015; 63:2133-51. [PMID: 25782611 PMCID: PMC4737250 DOI: 10.1002/glia.22821] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 03/02/2015] [Indexed: 12/27/2022]
Abstract
Memory formation in the brain is thought to rely on the remodeling of synaptic connections which eventually results in neural network rewiring. This remodeling is likely to involve ultrathin astroglial protrusions which often occur in the immediate vicinity of excitatory synapses. The phenomenology, cellular mechanisms, and causal relationships of such astroglial restructuring remain, however, poorly understood. This is in large part because monitoring and probing of the underpinning molecular machinery on the scale of nanoscopic astroglial compartments remains a challenge. Here we briefly summarize the current knowledge regarding the cellular organisation of astroglia in the synaptic microenvironment and discuss molecular mechanisms potentially involved in use-dependent astroglial morphogenesis. We also discuss recent observations concerning morphological astroglial plasticity, the respective monitoring methods, and some of the newly emerging techniques that might help with conceptual advances in the area.
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Affiliation(s)
- Janosch P Heller
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London, United Kingdom
| | - Dmitri A Rusakov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London, United Kingdom
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35
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The new nanophysiology: regulation of ionic flow in neuronal subcompartments. Nat Rev Neurosci 2015; 16:685-92. [PMID: 26462753 DOI: 10.1038/nrn4022] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cable theory and the Goldman-Hodgkin-Huxley-Katz models for the propagation of ions and voltage within a neuron have provided a theoretical foundation for electrophysiology and been responsible for many cornerstone advances in neuroscience. However, these theories break down when they are applied to small neuronal compartments, such as dendritic spines, synaptic terminals or small neuronal processes, because they assume spatial and ionic homogeneity. Here we discuss a broader theory that uses the Poisson-Nernst-Planck (PNP) approximation and electrodiffusion to more accurately model the constraints that neuronal nanostructures place on electrical current flow. This extension of traditional cable theory could advance our understanding of the physiology of neuronal nanocompartments.
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36
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de Bartolomeis A, Errico F, Aceto G, Tomasetti C, Usiello A, Iasevoli F. D-aspartate dysregulation in Ddo(-/-) mice modulates phencyclidine-induced gene expression changes of postsynaptic density molecules in cortex and striatum. Prog Neuropsychopharmacol Biol Psychiatry 2015; 62:35-43. [PMID: 25979765 DOI: 10.1016/j.pnpbp.2015.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/06/2015] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
Abstract
N-methyl-D-aspartate receptor (NMDAR) hypofunction has been considered a key alteration in schizophrenia pathophysiology. Thus, several strategies aimed at enhancing glutamatergic transmission, included the introduction in therapy of D-amino acids, such as D-serine and D-cycloserine augmentation, have been proposed to counteract difficult-to-treat symptoms or treatment-resistant forms of schizophrenia. Another D-amino acid, D-aspartate, has recently gained increasing interest for its role in NMDAR activation and has been found reduced in post-mortem cortex of schizophrenia patients. NMDAR is the core of the postsynaptic density (PSD), a postsynaptic site involved in glutamate signaling and responsive to antipsychotic treatment. In this study, we investigated striatal and cortical gene expression of key PSD transcripts (i.e. Homer1a, Homer1b/c, and PSD-95) in mice with persistently elevated brain D-aspartate-levels, i.e. the D-aspartate-oxidase knockout mice (Ddo(-/-)). These animal models were analyzed both in naive condition and after phencyclidine (PCP) treatment. Naive Ddo(-/-) mice showed decreased Homer1a expression in the prefrontal cortex, increased Homer1b/c expression in the striatum, and decreased PSD-95 expression in the striatum and in the cortex. Acute PCP treatment restored, and even potentiated, Homer1a expression in the prefrontal cortex of mutant mice, while it had limited effects on the other genes. These results suggest that persistently elevated D-aspartate, by enhancing NMDA transmission, may cause complex adaptive mechanisms affecting Homer1a, which in turn may explain the recently demonstrated protective effects of this D-amino acid against PCP-induced behavioral alterations, such as ataxic behavior.
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Affiliation(s)
- Andrea de Bartolomeis
- Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, Reproductive and Odontostomatological Sciences, University School of Medicine Federico II, Naples, Italy.
| | - Francesco Errico
- CEINGE Biotecnologie Avanzate, Naples, Italy; Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy
| | | | - Carmine Tomasetti
- Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, Reproductive and Odontostomatological Sciences, University School of Medicine Federico II, Naples, Italy
| | - Alessandro Usiello
- CEINGE Biotecnologie Avanzate, Naples, Italy; Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples (SUN), Caserta, Italy
| | - Felice Iasevoli
- Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, Reproductive and Odontostomatological Sciences, University School of Medicine Federico II, Naples, Italy
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37
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D'Antoni S, Spatuzza M, Bonaccorso CM, Musumeci SA, Ciranna L, Nicoletti F, Huber KM, Catania MV. Dysregulation of group-I metabotropic glutamate (mGlu) receptor mediated signalling in disorders associated with Intellectual Disability and Autism. Neurosci Biobehav Rev 2014; 46 Pt 2:228-41. [PMID: 24548786 DOI: 10.1016/j.neubiorev.2014.02.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 01/13/2014] [Accepted: 02/06/2014] [Indexed: 12/11/2022]
Abstract
Activation of group-I metabotropic glutamate receptors, mGlu1 and mGlu5, triggers a variety of signalling pathways in neurons and glial cells, which are differently implicated in synaptic plasticity. The earliest and much of key studies discovered abnormal mGlu5 receptor function in Fragile X syndrome (FXS) mouse models which then motivated more recent work that finds mGlu5 receptor dysfunction in related disorders such as intellectual disability (ID), obsessive-compulsive disorder (OCD) and autism. Therefore, mGlu1/5 receptor dysfunction may represent a common aetiology of these complex diseases. Furthermore, many studies have focused on dysregulation of mGlu5 signalling to synaptic protein synthesis. However, emerging evidence finds abnormal mGlu5 receptor interactions with its scaffolding proteins in FXS which results in mGlu5 receptor dysfunction and phenotypes independent of signalling to protein synthesis. Finally, both an increased and reduced mGlu5 functioning seem to be associated with ID and autism spectrum disorders, with important consequences for potential treatment of these developmental disorders.
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Affiliation(s)
- Simona D'Antoni
- Institute of Neurological Sciences, the National Research Council of Italy (CNR), Catania, Italy
| | - Michela Spatuzza
- Institute of Neurological Sciences, the National Research Council of Italy (CNR), Catania, Italy
| | | | | | - Lucia Ciranna
- Department of Biomedical Sciences, section of Physiology, University of Catania, Italy
| | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli (IS), Italy; University of Rome La Sapienza, Rome, Italy
| | - Kimberly M Huber
- University of Texas Southwestern Medical Center, Department of Neuroscience, Dallas, TX 75390-9111, USA
| | - Maria Vincenza Catania
- Institute of Neurological Sciences, the National Research Council of Italy (CNR), Catania, Italy; IRCCS Oasi Maria SS, Troina (EN), Italy.
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38
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Abushik PA, Niittykoski M, Giniatullina R, Shakirzyanova A, Bart G, Fayuk D, Sibarov DA, Antonov SM, Giniatullin R. The role of NMDA and mGluR5 receptors in calcium mobilization and neurotoxicity of homocysteine in trigeminal and cortical neurons and glial cells. J Neurochem 2013; 129:264-74. [DOI: 10.1111/jnc.12615] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 11/19/2013] [Accepted: 11/19/2013] [Indexed: 02/06/2023]
Affiliation(s)
- Polina A. Abushik
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
- Laboratory of Comparative Physiology of Cerebellum; Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Science; Saint-Petersburg Russia
| | - Minna Niittykoski
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
- Biotechnology and Molecular Medicine; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
| | - Raisa Giniatullina
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
| | - Anastasia Shakirzyanova
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
| | - Genevieve Bart
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
| | - Dmitriy Fayuk
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
| | - Dmitry A. Sibarov
- Laboratory of Comparative Physiology of Cerebellum; Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Science; Saint-Petersburg Russia
- Laboratory of Molecular Neurodegeneration; Saint-Petersburg State Polytechnic University; Saint-Petersburg Russia
| | - Sergei M. Antonov
- Laboratory of Comparative Physiology of Cerebellum; Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Science; Saint-Petersburg Russia
- Laboratory of Molecular Neurodegeneration; Saint-Petersburg State Polytechnic University; Saint-Petersburg Russia
| | - Rashid Giniatullin
- Department of Neurobiology; A. I. Virtanen Institute for Molecular Sciences; University of Eastern Finland; Kuopio Finland
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39
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Savtchenko LP, Rusakov DA. Moderate AMPA receptor clustering on the nanoscale can efficiently potentiate synaptic current. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130167. [PMID: 24298165 PMCID: PMC3843895 DOI: 10.1098/rstb.2013.0167] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The prevailing view at present is that postsynaptic expression of the classical NMDA receptor-dependent long-term potentiation relies on an increase in the numbers of local AMPA receptors (AMPARs). This is thought to parallel an expansion of postsynaptic cell specializations, for instance dendritic spine heads, which accommodate synaptic receptor proteins. However, glutamate released into the synaptic cleft can normally activate only a hotspot of low-affinity AMPARs that occur in the vicinity of the release site. How the enlargement of the AMPAR pool is causally related to the potentiated AMPAR current remains therefore poorly understood. To understand possible scenarios of postsynaptic potentiation, here we explore a detailed Monte Carlo model of the typical small excitatory synapse. Simulations suggest that approximately 50% increase in the synaptic AMPAR current could be provided by expanding the existing AMPAR pool at the expense of 100–200% new AMPARs added at the same packing density. Alternatively, reducing the inter-receptor distances by only 30–35% could achieve a similar level of current potentiation without any changes in the receptor numbers. The NMDA receptor current also appears sensitive to the NMDA receptor crowding. Our observations provide a quantitative framework for understanding the ‘resource-efficient’ ways to enact use-dependent changes in the architecture of central synapses.
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Affiliation(s)
- Leonid P Savtchenko
- UCL Institute of Neurology, University College London, , Queen Square, London WC1N 3BG, UK
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40
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Sylantyev S, Rusakov DA. Sub-millisecond ligand probing of cell receptors with multiple solution exchange. Nat Protoc 2013; 8:1299-306. [PMID: 23744290 PMCID: PMC3743020 DOI: 10.1038/nprot.2013.075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The accurate knowledge of receptor kinetics is crucial to our understanding of cell signal transduction in general and neural function in particular. The classical technique of probing membrane receptors on a millisecond scale involves placing a recording micropipette with a membrane patch in front of a double-barrel (θ-glass) application pipette mounted on a piezo actuator. Driven by electric pulses, the actuator can rapidly shift the θ-glass pipette tip, thus exposing the target receptors to alternating ligand solutions. However, membrane patches survive for only a few minutes, thus normally restricting such experiments to a single-application protocol. In order to overcome this deficiency, we have introduced pressurized supply microcircuits in the θ-glass channels, thus enabling repeated replacement of application solutions within 10-15 s. This protocol, which has been validated in our recent studies and takes 20-60 min to implement, allows the characterization of ligand-receptor interactions with high sensitivity, thereby also enabling a powerful paired-sample statistical design.
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Affiliation(s)
- Sergiy Sylantyev
- UCL Institute of Neurology, University College London, London, UK.
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41
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Schwartz E, Barbour B. A spike of electrodiffusion reaches metabotropic receptors. Neuron 2013; 77:381-4. [PMID: 23395368 DOI: 10.1016/j.neuron.2013.01.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Flow of current in the synaptic cleft can influence diffusion of charged transmitters, such as glutamate. In this issue of Neuron, Sylantyev et al. (2013) demonstrate how this can modulate synaptic NMDA receptor-mediated responses via a surprising mechanism-perisynaptic metabotropic glutamate receptors.
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Affiliation(s)
- Eric Schwartz
- Institut de Biologie de l'ENS, IBENS, F-75005 Paris, France
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42
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Henneberger C, Bard L, King C, Jennings A, Rusakov DA. NMDA Receptor Activation: Two Targets for Two Co-Agonists. Neurochem Res 2013; 38:1156-62. [DOI: 10.1007/s11064-013-0987-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 01/27/2013] [Accepted: 01/28/2013] [Indexed: 12/01/2022]
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