1
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Prikhodko O, Freund RK, Sullivan E, Kennedy MJ, Dell'Acqua ML. Amyloid-β Causes NMDA Receptor Dysfunction and Dendritic Spine Loss through mGluR1 and AKAP150-Anchored Calcineurin Signaling. J Neurosci 2024; 44:e0675242024. [PMID: 39134419 PMCID: PMC11391497 DOI: 10.1523/jneurosci.0675-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 07/08/2024] [Accepted: 07/30/2024] [Indexed: 09/13/2024] Open
Abstract
Neuronal excitatory synapses are primarily located on small dendritic protrusions called spines. During synaptic plasticity underlying learning and memory, Ca2+ influx through postsynaptic NMDA-type glutamate receptors (NMDARs) initiates signaling pathways that coordinate changes in dendritic spine structure and synaptic function. During long-term potentiation (LTP), high levels of NMDAR Ca2+ influx promote increases in both synaptic strength and dendritic spine size through activation of Ca2+-dependent protein kinases. In contrast, during long-term depression (LTD), low levels of NMDAR Ca2+ influx promote decreased synaptic strength and spine shrinkage and elimination through activation of the Ca2+-dependent protein phosphatase calcineurin (CaN), which is anchored at synapses via the scaffold protein A-kinase anchoring protein (AKAP)150. In Alzheimer's disease (AD), the pathological agent amyloid-β (Aβ) may impair learning and memory through biasing NMDAR Ca2+ signaling pathways toward LTD and spine elimination. By employing AKAP150 knock-in mice of both sexes with a mutation that disrupts CaN anchoring to AKAP150, we revealed that local, postsynaptic AKAP-CaN-LTD signaling was required for Aβ-mediated impairment of NMDAR synaptic Ca2+ influx, inhibition of LTP, and dendritic spine loss. Additionally, we found that Aβ acutely engages AKAP-CaN signaling through activation of G-protein-coupled metabotropic glutamate receptor 1 (mGluR1) leading to dephosphorylation of NMDAR GluN2B subunits, which decreases Ca2+ influx to favor LTD over LTP, and cofilin, which promotes F-actin severing to destabilize dendritic spines. These findings reveal a novel interplay between NMDAR and mGluR1 signaling that converges on AKAP-anchored CaN to coordinate dephosphorylation of postsynaptic substrates linked to multiple aspects of Aβ-mediated synaptic dysfunction.
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Affiliation(s)
- Olga Prikhodko
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Ronald K Freund
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
- Alzheimer's and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Emily Sullivan
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Matthew J Kennedy
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
- Neurotechnology Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
- Neurotechnology Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
- Alzheimer's and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
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2
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Han X, Lu X, Li PH, Wang S, Schalek R, Meirovitch Y, Lin Z, Adhinarta J, Murray KD, MacNiven LM, Berger DR, Wu Y, Fang T, Meral ES, Asraf S, Ploegh H, Pfister H, Wei D, Jain V, Trimmer JS, Lichtman JW. Multiplexed volumetric CLEM enabled by scFvs provides insights into the cytology of cerebellar cortex. Nat Commun 2024; 15:6648. [PMID: 39103318 DOI: 10.1038/s41467-024-50411-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 07/01/2024] [Indexed: 08/07/2024] Open
Abstract
Mapping neuronal networks is a central focus in neuroscience. While volume electron microscopy (vEM) can reveal the fine structure of neuronal networks (connectomics), it does not provide molecular information to identify cell types or functions. We developed an approach that uses fluorescent single-chain variable fragments (scFvs) to perform multiplexed detergent-free immunolabeling and volumetric-correlated-light-and-electron-microscopy on the same sample. We generated eight fluorescent scFvs targeting brain markers. Six fluorescent probes were imaged in the cerebellum of a female mouse, using confocal microscopy with spectral unmixing, followed by vEM of the same sample. The results provide excellent ultrastructure superimposed with multiple fluorescence channels. Using this approach, we documented a poorly described cell type, two types of mossy fiber terminals, and the subcellular localization of one type of ion channel. Because scFvs can be derived from existing monoclonal antibodies, hundreds of such probes can be generated to enable molecular overlays for connectomic studies.
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Affiliation(s)
- Xiaomeng Han
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
| | - Xiaotang Lu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
| | | | - Shuohong Wang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Richard Schalek
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Yaron Meirovitch
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Zudi Lin
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Jason Adhinarta
- Computer Science Department, Boston College, Chestnut Hill, MA, USA
| | - Karl D Murray
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA, USA
| | - Leah M MacNiven
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA, USA
| | - Daniel R Berger
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Yuelong Wu
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Tao Fang
- Program of Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | | | - Shadnan Asraf
- School of Public Health, University of Massachusetts Amherst, Amherst, MA, USA
| | - Hidde Ploegh
- Program of Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Hanspeter Pfister
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA, USA
| | - Donglai Wei
- Computer Science Department, Boston College, Chestnut Hill, MA, USA
| | | | - James S Trimmer
- Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA, USA
| | - Jeff W Lichtman
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA.
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3
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Griffin H, Hanson J, Phelan KD, Baldini G. MC4R Localizes at Excitatory Postsynaptic and Peri-Postsynaptic Sites of Hypothalamic Neurons in Primary Culture. Cells 2024; 13:1235. [PMID: 39120267 PMCID: PMC11311852 DOI: 10.3390/cells13151235] [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: 04/28/2024] [Revised: 07/13/2024] [Accepted: 07/18/2024] [Indexed: 08/10/2024] Open
Abstract
The melanocortin-4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain locations encompassing the hypothalamus and the brainstem, where the receptor controls several body functions, including metabolism. In a well-defined pathway to decrease appetite, hypothalamic proopiomelanocortin (POMC) neurons localized in the arcuate nucleus (Arc) project to MC4R neurons in the paraventricular nuclei (PVN) to release the natural MC4R agonist α-melanocyte-stimulating hormone (α-MSH). Arc neurons also project excitatory glutamatergic fibers to the MC4R neurons in the PVN for a fast synaptic transmission to regulate a satiety pathway potentiated by α-MSH. By using super-resolution microscopy, we found that in hypothalamic neurons in a primary culture, postsynaptic density protein 95 (PSD95) colocalizes with GluN1, a subunit of the ionotropic N-methyl-D-aspartate receptor (NMDAR). Thus, hypothalamic neurons form excitatory postsynaptic specializations. To study the MC4R distribution at these sites, tagged HA-MC4R under the synapsin promoter was expressed in neurons by adeno-associated virus (AAV) gene transduction. HA-MC4R immunofluorescence peaked at the center and in proximity to the PSD95- and NMDAR-expressing sites. These data provide morphological evidence that MC4R localizes together with glutamate receptors at postsynaptic and peri-postsynaptic sites.
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Affiliation(s)
- Haven Griffin
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Jude Hanson
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
| | - Kevin D. Phelan
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA;
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA; (H.G.); (J.H.)
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4
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Dwivedi D, Dumontier D, Sherer M, Lin S, Mirow AMC, Qiu Y, Xu Q, Liebman SA, Joseph D, Datta SR, Fishell G, Pouchelon G. Metabotropic signaling within somatostatin interneurons controls transient thalamocortical inputs during development. Nat Commun 2024; 15:5421. [PMID: 38926335 PMCID: PMC11208423 DOI: 10.1038/s41467-024-49732-w] [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: 12/18/2023] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
During brain development, neural circuits undergo major activity-dependent restructuring. Circuit wiring mainly occurs through synaptic strengthening following the Hebbian "fire together, wire together" precept. However, select connections, essential for circuit development, are transient. They are effectively connected early in development, but strongly diminish during maturation. The mechanisms by which transient connectivity recedes are unknown. To investigate this process, we characterize transient thalamocortical inputs, which depress onto somatostatin inhibitory interneurons during development, by employing optogenetics, chemogenetics, transcriptomics and CRISPR-based strategies in mice. We demonstrate that in contrast to typical activity-dependent mechanisms, transient thalamocortical connectivity onto somatostatin interneurons is non-canonical and involves metabotropic signaling. Specifically, metabotropic-mediated transcription, of guidance molecules in particular, supports the elimination of this connectivity. Remarkably, we found that this process impacts the development of normal exploratory behaviors of adult mice.
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Affiliation(s)
- Deepanjali Dwivedi
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA
| | | | - Mia Sherer
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA
| | - Sherry Lin
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
| | - Andrea M C Mirow
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA
- Cold Spring Harbor Laboratory, Cold Spring Harbor, Harbor, NY, USA
| | - Yanjie Qiu
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA
| | - Qing Xu
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Abu Dhabi, UAE
| | - Samuel A Liebman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, Harbor, NY, USA
| | - Djeckby Joseph
- Cold Spring Harbor Laboratory, Cold Spring Harbor, Harbor, NY, USA
| | - Sandeep R Datta
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA
| | - Gord Fishell
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA.
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA.
| | - Gabrielle Pouchelon
- Harvard Medical School, Department of Neurobiology, Boston, MA, USA.
- Broad Institute, Stanley Center for Psychiatric Research, Cambridge, MA, USA.
- Cold Spring Harbor Laboratory, Cold Spring Harbor, Harbor, NY, USA.
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5
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Voerman S, Broersen R, Swagemakers SMA, De Zeeuw CI, van der Spek PJ. Plasticity mechanisms of genetically distinct Purkinje cells. Bioessays 2024; 46:e2400008. [PMID: 38697917 DOI: 10.1002/bies.202400008] [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: 01/12/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 05/05/2024]
Abstract
Despite its uniform appearance, the cerebellar cortex is highly heterogeneous in terms of structure, genetics and physiology. Purkinje cells (PCs), the principal and sole output neurons of the cerebellar cortex, can be categorized into multiple populations that differentially express molecular markers and display distinctive physiological features. Such features include action potential rate, but also their propensity for synaptic and intrinsic plasticity. However, the precise molecular and genetic factors that correlate with the differential physiological properties of PCs remain elusive. In this article, we provide a detailed overview of the cellular mechanisms that regulate PC activity and plasticity. We further perform a pathway analysis to highlight how molecular characteristics of specific PC populations may influence their physiology and plasticity mechanisms.
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Affiliation(s)
- Stijn Voerman
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
| | - Robin Broersen
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
| | - Sigrid M A Swagemakers
- Department of Pathology and Clinical Bioinformatics, Erasmus MC, Rotterdam, The Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Peter J van der Spek
- Department of Pathology and Clinical Bioinformatics, Erasmus MC, Rotterdam, The Netherlands
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6
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Dwivedi D, Dumontier D, Sherer M, Lin S, Mirow AM, Qiu Y, Xu Q, Liebman SA, Joseph D, Datta SR, Fishell G, Pouchelon G. Metabotropic signaling within somatostatin interneurons controls transient thalamocortical inputs during development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.21.558862. [PMID: 37790336 PMCID: PMC10542166 DOI: 10.1101/2023.09.21.558862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
During brain development, neural circuits undergo major activity-dependent restructuring. Circuit wiring mainly occurs through synaptic strengthening following the Hebbian "fire together, wire together" precept. However, select connections, essential for circuit development, are transient. They are effectively connected early in development, but strongly diminish during maturation. The mechanisms by which transient connectivity recedes are unknown. To investigate this process, we characterize transient thalamocortical inputs, which depress onto somatostatin inhibitory interneurons during development, by employing optogenetics, chemogenetics, transcriptomics and CRISPR-based strategies. We demonstrate that in contrast to typical activity-dependent mechanisms, transient thalamocortical connectivity onto somatostatin interneurons is non-canonical and involves metabotropic signaling. Specifically, metabotropic-mediated transcription, of guidance molecules in particular, supports the elimination of this connectivity. Remarkably, we found that this developmental process impacts the development of normal exploratory behaviors of adult mice.
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7
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Fujiyama F, Karube F. Pre- and Postembedding Immunoelectron Microscopy to Analyze the Central Nervous System. Methods Mol Biol 2024; 2794:45-62. [PMID: 38630219 DOI: 10.1007/978-1-0716-3810-1_5] [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] [Indexed: 04/19/2024]
Abstract
Immunocytochemistry, a method of delineating the subcellular localization of target proteins, was developed from immunohistochemistry. In principle, proteins are labeled using an antigen-antibody reaction. In order to observe under an electron microscope, the reaction product must scatter the electron beam with sufficient contrast while it is necessary to have an amplifying label that can withstand the observation. We have some detailed tips on making electron microscope samples to achieve this objective, and we would be happy to help you.
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Affiliation(s)
- Fumino Fujiyama
- Laboratory of Histology and Cytology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
| | - Fuyuki Karube
- Laboratory of Histology and Cytology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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8
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Grigoryan G, Harada H, Knobloch-Bollmann HS, Kilias A, Kaufhold D, Kulik A, Eyre MD, Bartos M. Synaptic plasticity at the dentate gyrus granule cell to somatostatin-expressing interneuron synapses supports object location memory. Proc Natl Acad Sci U S A 2023; 120:e2312752120. [PMID: 38091292 PMCID: PMC10742375 DOI: 10.1073/pnas.2312752120] [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: 07/25/2023] [Accepted: 10/14/2023] [Indexed: 12/18/2023] Open
Abstract
Somatostatin-expressing interneurons (SOMIs) in the mouse dentate gyrus (DG) receive feedforward excitation from granule cell (GC) mossy fiber (MF) synapses and provide feedback lateral inhibition onto GC dendrites to support environment representation in the DG network. Although this microcircuitry has been implicated in memory formation, little is known about activity-dependent plastic changes at MF-SOMI synapses and their influence on behavior. Here, we report that the metabotropic glutamate receptor 1α (mGluR1α) is required for the induction of associative long-term potentiation (LTP) at MF-SOMI synapses. Pharmacological block of mGluR1α, but not mGluR5, prevented synaptic weight changes. LTP at MF-SOMI synapses was postsynaptically induced, required increased intracellular Ca2+, involved G-protein-mediated and Ca2+-dependent (extracellular signal-regulated kinase) ERK1/2 pathways, and the activation of NMDA receptors. Specific knockdown of mGluR1α in DG-SOMIs by small hairpin RNA expression prevented MF-SOMI LTP, reduced SOMI recruitment, and impaired object location memory. Thus, postsynaptic mGluR1α-mediated MF-plasticity at SOMI input synapses critically supports DG-dependent mnemonic functions.
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Affiliation(s)
- Gayane Grigoryan
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Harumi Harada
- Molecular Physiology, Institute for Physiology II, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - H. Sophie Knobloch-Bollmann
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Antje Kilias
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Dorthe Kaufhold
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Akos Kulik
- Molecular Physiology, Institute for Physiology II, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Mark D. Eyre
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
| | - Marlene Bartos
- Laboratory of Systems & Cellular Neuroscience, Institute for Physiology I, Medical Faculty, University of Freiburg, Freiburg79104, Germany
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9
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Han X, Lu X, Li PH, Wang S, Schalek R, Meirovitch Y, Lin Z, Adhinarta J, Berger D, Wu Y, Fang T, Meral ES, Asraf S, Ploegh H, Pfister H, Wei D, Jain V, Trimmer JS, Lichtman JW. Multiplexed volumetric CLEM enabled by antibody derivatives provides new insights into the cytology of the mouse cerebellar cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.20.540091. [PMID: 37292964 PMCID: PMC10245788 DOI: 10.1101/2023.05.20.540091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mapping neuronal networks that underlie behavior has become a central focus in neuroscience. While serial section electron microscopy (ssEM) can reveal the fine structure of neuronal networks (connectomics), it does not provide the molecular information that helps identify cell types or their functional properties. Volumetric correlated light and electron microscopy (vCLEM) combines ssEM and volumetric fluorescence microscopy to incorporate molecular labeling into ssEM datasets. We developed an approach that uses small fluorescent single-chain variable fragment (scFv) immuno-probes to perform multiplexed detergent-free immuno-labeling and ssEM on the same samples. We generated eight such fluorescent scFvs that targeted useful markers for brain studies (green fluorescent protein, glial fibrillary acidic protein, calbindin, parvalbumin, voltage-gated potassium channel subfamily A member 2, vesicular glutamate transporter 1, postsynaptic density protein 95, and neuropeptide Y). To test the vCLEM approach, six different fluorescent probes were imaged in a sample of the cortex of a cerebellar lobule (Crus 1), using confocal microscopy with spectral unmixing, followed by ssEM imaging of the same sample. The results show excellent ultrastructure with superimposition of the multiple fluorescence channels. Using this approach we could document a poorly described cell type in the cerebellum, two types of mossy fiber terminals, and the subcellular localization of one type of ion channel. Because scFvs can be derived from existing monoclonal antibodies, hundreds of such probes can be generated to enable molecular overlays for connectomic studies.
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10
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Mango D, Ledonne A. Updates on the Physiopathology of Group I Metabotropic Glutamate Receptors (mGluRI)-Dependent Long-Term Depression. Cells 2023; 12:1588. [PMID: 37371058 DOI: 10.3390/cells12121588] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/01/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
Group I metabotropic glutamate receptors (mGluRI), including mGluR1 and mGluR5 subtypes, modulate essential brain functions by affecting neuronal excitability, intracellular calcium dynamics, protein synthesis, dendritic spine formation, and synaptic transmission and plasticity. Nowadays, it is well appreciated that the mGluRI-dependent long-term depression (LTD) of glutamatergic synaptic transmission (mGluRI-LTD) is a key mechanism by which mGluRI shapes connectivity in various cerebral circuitries, directing complex brain functions and behaviors, and that it is deranged in several neurological and psychiatric illnesses, including neurodevelopmental disorders, neurodegenerative diseases, and psychopathologies. Here, we will provide an updated overview of the physiopathology of mGluRI-LTD, by describing mechanisms of induction and regulation by endogenous mGluRI interactors, as well as functional physiological implications and pathological deviations.
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Affiliation(s)
- Dalila Mango
- School of Pharmacy, University of Rome "Tor Vergata", 00133 Rome, Italy
- Laboratory of Pharmacology of Synaptic Plasticity, European Brain Research Institute, 00161 Rome, Italy
| | - Ada Ledonne
- Department of Systems Medicine, University of Rome "Tor Vergata", 00133 Rome, Italy
- Department of Experimental Neuroscience, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
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11
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Mansouri M, Kremser L, Nguyen TP, Kasugai Y, Caberlotto L, Gassmann M, Sarg B, Lindner H, Bettler B, Carboni L, Ferraguti F. Protein Networks Associated with Native Metabotropic Glutamate 1 Receptors (mGlu 1) in the Mouse Cerebellum. Cells 2023; 12:1325. [PMID: 37174725 PMCID: PMC10177021 DOI: 10.3390/cells12091325] [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: 03/17/2023] [Revised: 04/28/2023] [Accepted: 04/30/2023] [Indexed: 05/15/2023] Open
Abstract
The metabotropic glutamate receptor 1 (mGlu1) plays a pivotal role in synaptic transmission and neuronal plasticity. Despite the fact that several interacting proteins involved in the mGlu1 subcellular trafficking and intracellular transduction mechanisms have been identified, the protein network associated with this receptor in specific brain areas remains largely unknown. To identify novel mGlu1-associated protein complexes in the mouse cerebellum, we used an unbiased tissue-specific proteomic approach, namely co-immunoprecipitation followed by liquid chromatography/tandem mass spectrometry analysis. Many well-known protein complexes as well as novel interactors were identified, including G-proteins, Homer, δ2 glutamate receptor, 14-3-3 proteins, and Na/K-ATPases. A novel putative interactor, KCTD12, was further investigated. Reverse co-immunoprecipitation with anti-KCTD12 antibodies revealed mGlu1 in wild-type but not in KCTD12-knock-out homogenates. Freeze-fracture replica immunogold labeling co-localization experiments showed that KCTD12 and mGlu1 are present in the same nanodomain in Purkinje cell spines, although at a distance that suggests that this interaction is mediated through interposed proteins. Consistently, mGlu1 could not be co-immunoprecipitated with KCTD12 from a recombinant mammalian cell line co-expressing the two proteins. The possibility that this interaction was mediated via GABAB receptors was excluded by showing that mGlu1 and KCTD12 still co-immunoprecipitated from GABAB receptor knock-out tissue. In conclusion, this study identifies tissue-specific mGlu1-associated protein clusters including KCTD12 at Purkinje cell synapses.
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Affiliation(s)
- Mahnaz Mansouri
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
| | - Leopold Kremser
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | | | - Yu Kasugai
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
| | - Laura Caberlotto
- Centre for Computational and Systems Biology (COSBI), The Microsoft Research University of Trento, 38068 Rovereto, Italy;
| | - Martin Gassmann
- Department of Biomedicine, Pharmazentrum, University of Basel, 4056 Basel, Switzerland; (M.G.); (B.B.)
| | - Bettina Sarg
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | - Herbert Lindner
- Institute of Medical Biochemistry, Protein Core Facility, Medical University of Innsbruck, 6020 Innsbruck, Austria; (L.K.); (B.S.); (H.L.)
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of Basel, 4056 Basel, Switzerland; (M.G.); (B.B.)
| | - Lucia Carboni
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum University of Bologna, 40126 Bologna, Italy;
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (Y.K.)
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12
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mGluR5 is transiently confined in perisynaptic nanodomains to shape synaptic function. Nat Commun 2023; 14:244. [PMID: 36646691 PMCID: PMC9842668 DOI: 10.1038/s41467-022-35680-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 12/19/2022] [Indexed: 01/18/2023] Open
Abstract
The unique perisynaptic distribution of postsynaptic metabotropic glutamate receptors (mGluRs) at excitatory synapses is predicted to directly shape synaptic function, but mechanistic insight into how this distribution is regulated and impacts synaptic signaling is lacking. We used live-cell and super-resolution imaging approaches, and developed molecular tools to resolve and acutely manipulate the dynamic nanoscale distribution of mGluR5. Here we show that mGluR5 is dynamically organized in perisynaptic nanodomains that localize close to, but not in the synapse. The C-terminal domain of mGluR5 critically controlled perisynaptic confinement and prevented synaptic entry. We developed an inducible interaction system to overcome synaptic exclusion of mGluR5 and investigate the impact on synaptic function. We found that mGluR5 recruitment to the synapse acutely increased synaptic calcium responses. Altogether, we propose that transient confinement of mGluR5 in perisynaptic nanodomains allows flexible modulation of synaptic function.
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13
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Group I Metabotropic Glutamate Receptors Modulate Motility and Enteric Neural Activity in the Mouse Colon. Biomolecules 2023; 13:biom13010139. [PMID: 36671524 PMCID: PMC9856182 DOI: 10.3390/biom13010139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system, and there is evidence that Group-I metabotropic glutamate receptors (mGlu1 and mGlu5) have established roles in excitatory neurotransmission and synaptic plasticity. While glutamate is abundantly present in the gut, it plays a smaller role in neurotransmission in the enteric nervous system. In this study, we examined the roles of Group-I mGlu receptors in gastrointestinal function. We investigated the expression of Grm1 (mGlu1) and Grm5 (mGlu5) in the mouse myenteric plexus using RNAscope in situ hybridization. Live calcium imaging and motility analysis were performed on ex vivo preparations of the mouse colon. mGlu5 was found to play a role in excitatory enteric neurotransmission, as electrically-evoked calcium transients were sensitive to the mGlu5 antagonist MPEP. However, inhibition of mGlu5 activity did not affect colonic motor complexes (CMCs). Instead, inhibition of mGlu1 using BAY 36-7620 reduced CMC frequency but did not affect enteric neurotransmission. These data highlight complex roles for Group-I mGlu receptors in myenteric neuron activity and colonic function.
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14
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Hoglund BK, Carfagno V, Olive MF, Leyrer-Jackson JM. Metabotropic glutamate receptors and cognition: From underlying plasticity and neuroprotection to cognitive disorders and therapeutic targets. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 168:367-413. [PMID: 36868635 DOI: 10.1016/bs.irn.2022.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors that play pivotal roles in mediating the activity of neurons and other cell types within the brain, communication between cell types, synaptic plasticity, and gene expression. As such, these receptors play an important role in a number of cognitive processes. In this chapter, we discuss the role of mGlu receptors in various forms of cognition and their underlying physiology, with an emphasis on cognitive dysfunction. Specifically, we highlight evidence that links mGlu physiology to cognitive dysfunction across brain disorders including Parkinson's disease, Alzheimer's disease, Fragile X syndrome, post-traumatic stress disorder, and schizophrenia. We also provide recent evidence demonstrating that mGlu receptors may elicit neuroprotective effects in particular disease states. Lastly, we discuss how mGlu receptors can be targeted utilizing positive and negative allosteric modulators as well as subtype specific agonists and antagonist to restore cognitive function across these disorders.
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Affiliation(s)
- Brandon K Hoglund
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States
| | - Vincent Carfagno
- School of Medicine, Midwestern University, Glendale, AZ, United States
| | - M Foster Olive
- Department of Psychology, Arizona State University, Tempe, AZ, United States
| | - Jonna M Leyrer-Jackson
- Department of Medical Education, School of Medicine, Creighton University, Phoenix, AZ, United States.
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15
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de Lima IB, Ribeiro FM. The Implication of Glial Metabotropic Glutamate Receptors in Alzheimer's Disease. Curr Neuropharmacol 2023; 21:164-182. [PMID: 34951388 PMCID: PMC10190153 DOI: 10.2174/1570159x20666211223140303] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 11/22/2022] Open
Abstract
Alzheimer's disease (AD) was first identified more than 100 years ago, yet aspects pertaining to its origin and the mechanisms underlying disease progression are not well known. To this date, there is no therapeutic approach or disease-modifying drug that could halt or at least delay disease progression. Until recently, glial cells were seen as secondary actors in brain homeostasis. Although this view was gradually refuted and the relevance of glial cells for the most diverse brain functions such as synaptic plasticity and neurotransmission was vastly proved, many aspects of its functioning, as well as its role in pathological conditions, remain poorly understood. Metabotropic glutamate receptors (mGluRs) in glial cells were shown to be involved in neuroinflammation and neurotoxicity. Besides its relevance for glial function, glutamatergic receptors are also central in the pathology of AD, and recent studies have shown that glial mGluRs play a role in the establishment and progression of AD. AD-related alterations in Ca2+ signalling, APP processing, and Aβ load, as well as AD-related neurodegeneration, are influenced by glial mGluRs. However, different types of mGluRs play different roles, depending on the cell type and brain region that is being analysed. Therefore, in this review, we focus on the current understanding of glial mGluRs and their implication in AD, providing an insight for future therapeutics and identifying existing research gaps worth investigating.
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Affiliation(s)
- Izabella B.Q. de Lima
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fabíola M. Ribeiro
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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16
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Surdin T, Preissing B, Rohr L, Grömmke M, Böke H, Barcik M, Azimi Z, Jancke D, Herlitze S, Mark MD, Siveke I. Optogenetic activation of mGluR1 signaling in the cerebellum induces synaptic plasticity. iScience 2022; 26:105828. [PMID: 36632066 PMCID: PMC9826949 DOI: 10.1016/j.isci.2022.105828] [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: 04/12/2022] [Revised: 10/21/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Neuronal plasticity underlying cerebellar learning behavior is strongly associated with type 1 metabotropic glutamate receptor (mGluR1) signaling. Activation of mGluR1 leads to activation of the Gq/11 pathway, which is involved in inducing synaptic plasticity at the parallel fiber-Purkinje cell synapse (PF-PC) in form of long-term depression (LTD). To optogenetically modulate mGluR1 signaling we fused mouse melanopsin (OPN4) that activates the Gq/11 pathway to the C-termini of mGluR1 splice variants (OPN4-mGluR1a and OPN4-mGluR1b). Activation of both OPN4-mGluR1 variants showed robust Ca2+ increase in HEK cells and PCs of cerebellar slices. We provide the prove-of-concept approach to modulate synaptic plasticity via optogenetic activation of OPN4-mGluR1a inducing LTD at the PF-PC synapse in vitro. Moreover, we demonstrate that light activation of mGluR1a signaling pathway by OPN4-mGluR1a in PCs leads to an increase in intrinsic activity of PCs in vivo and improved cerebellum driven learning behavior.
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Affiliation(s)
- Tatjana Surdin
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Bianca Preissing
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Lennard Rohr
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Michelle Grömmke
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Hanna Böke
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Maike Barcik
- Cardiovascular Research Institute Düsseldorf, Division of Cardiology, Pulmonology, and Vascular Medicine, University Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Zohre Azimi
- Optical Imaging Group, Institut für Neuroinformatik, Ruhr-University Bochum, Bochum, Germany
| | - Dirk Jancke
- Optical Imaging Group, Institut für Neuroinformatik, Ruhr-University Bochum, Bochum, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany,Corresponding author
| | - Melanie D. Mark
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Ida Siveke
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany,Bridge Institute of Experimental Tumor Therapy, West German Cancer Center, University Hospital Essen, Essen, Germany,Corresponding author
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17
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Fabian CB, Seney ML, Joffe ME. Sex differences and hormonal regulation of metabotropic glutamate receptor synaptic plasticity. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2022; 168:311-347. [PMID: 36868632 PMCID: PMC10392610 DOI: 10.1016/bs.irn.2022.10.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Striking sex differences exist in presentation and incidence of several psychiatric disorders. For example, major depressive disorder is more prevalent in women than men, and women who develop alcohol use disorder progress through drinking milestones more rapidly than men. With regards to psychiatric treatment responses, women respond more favorably to selective serotonin reuptake inhibitors than men, whereas men have better outcomes when prescribed tricyclic antidepressants. Despite such well-documented biases in incidence, presentation, and treatment response, sex as a biological variable has long been neglected in preclinical and clinical research. An emerging family of druggable targets for psychiatric diseases, metabotropic glutamate (mGlu) receptors are G-protein coupled receptors broadly distributed throughout the central nervous system. mGlu receptors confer diverse neuromodulatory actions of glutamate at the levels of synaptic plasticity, neuronal excitability, and gene transcription. In this chapter, we summarize the current preclinical and clinical evidence for sex differences in mGlu receptor function. We first highlight basal sex differences in mGlu receptor expression and function and proceed to describe how gonadal hormones, notably estradiol, regulate mGlu receptor signaling. We then describe sex-specific mechanisms by which mGlu receptors differentially modulate synaptic plasticity and behavior in basal states and models relevant for disease. Finally, we discuss human research findings and highlight areas in need of further research. Taken together, this review emphasizes how mGlu receptor function and expression can differ across sex. Gaining a more complete understanding of how sex differences in mGlu receptor function contribute to psychiatric diseases will be critical in the development of novel therapeutics that are effective in all individuals.
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Affiliation(s)
- Carly B Fabian
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States; Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States; Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, United States
| | - Marianne L Seney
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States; Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States; Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, United States
| | - Max E Joffe
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States; Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States; Translational Neuroscience Program, University of Pittsburgh, Pittsburgh, PA, United States.
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18
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Burghard AL, Lee CM, Fabrizio-Stover EM, Oliver DL. Long-Duration Sound-Induced Facilitation Changes Population Activity in the Inferior Colliculus. Front Syst Neurosci 2022; 16:920642. [PMID: 35873097 PMCID: PMC9301083 DOI: 10.3389/fnsys.2022.920642] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
The inferior colliculus (IC) is at the midpoint of the auditory system and integrates virtually all information ascending from the auditory brainstem, organizes it, and transmits the results to the auditory forebrain. Its abundant, excitatory local connections are crucial for this task. This study describes a long duration sound (LDS)-induced potentiation in the IC that changes both subsequent tone-evoked responses and spontaneous activity. Afterdischarges, changes of spontaneous spiking following an LDS, were seen previously in single neurons. Here, we used multi-channel probes to record activity before and after a single, tetanic sound and describe the changes in a population of IC neurons. Following a 60 s narrowband-noise stimulation, a subset of recording channels (∼16%) showed afterdischarges. A facilitated response spike rate to tone pips following an LDS was also observed in ∼16% of channels. Both channels with an afterdischarge and channels with facilitated tone responses had higher firing rates in response to LDS, and the magnitude of the afterdischarges increased with increased responses to the LDS. This is the first study examining the effect of LDS stimulation on tone-evoked responses. This observed facilitation in vivo has similarities to post-tetanic potentiation in vitro as both manner of induction (strong stimulation for several seconds) as well as time-course of the facilitation (second to minute range) are comparable. Channels with and without facilitation appear to be intermixed and distributed widely in the central nucleus of IC, and this suggests a heretofore unknown property of some IC neurons or their circuits. Consequently, this sound-evoked facilitation may enhance the sound-evoked output of these neurons, while, simultaneously, most other IC neurons have reduced or unchanged output in response to the same stimulus.
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19
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Aslam N, Alvi F. TRPC3 Channel Activity and Viability of Purkinje Neurons can be Regulated by a Local Signalosome. Front Mol Biosci 2022; 9:818682. [PMID: 35265671 PMCID: PMC8899209 DOI: 10.3389/fmolb.2022.818682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/03/2022] [Indexed: 11/19/2022] Open
Abstract
Canonical transient receptor potential channels (TRPC3) may play a pivotal role in the development and viability of dendritic arbor in Purkinje neurons. This is a novel postsynaptic channel for glutamatergic synaptic transmission. In the cerebellum, TRPC3 appears to regulate functions relating to motor coordination in a highly specific manner. Gain of TRPC3 function is linked to significant alterations in the density and connectivity of dendritic arbor in Purkinje neurons. TRPC3 signals downstream of class I metabotropic glutamate receptors (mGluR1). Moreover, diacylglycerol (DAG) can directly bind and activate TRPC3 molecules. Here, we investigate a key question: How can the activity of the TRPC3 channel be regulated in Purkinje neurons? We also explore how mGluR1 activation, Ca2+ influx, and DAG homeostasis in Purkinje neurons can be linked to TRPC3 activity modulation. Through systems biology approach, we show that TRPC3 activity can be modulated by a Purkinje cell (PC)–specific local signalosome. The assembly of this signalosome is coordinated by DAG generation after mGluR1 activation. Our results also suggest that purinergic receptor activation leads to the spatial and temporal organization of the TRPC3 signaling module and integration of its key effector molecules such as DAG, PKCγ, DGKγ, and Ca2+ into an organized local signalosome. This signaling machine can regulate the TRPC3 cycling between active, inactive, and desensitized states. Precise activity of the TRPC3 channel is essential for tightly regulating the Ca2+ entry into PCs and thus the balance of lipid and Ca2+ signaling in Purkinje neurons and hence their viability. Cell-type–specific understanding of mechanisms regulating TRPC3 channel activity could be key in identifying therapeutic targeting opportunities.
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Affiliation(s)
- Naveed Aslam
- BioSystOmics, Houston, TX, United States
- *Correspondence: Naveed Aslam,
| | - Farah Alvi
- BioSystOmics, Houston, TX, United States
- Department of Physics, COMSATS University Islamabad, Lahore Campus, Pakistan
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20
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Garzón M, Chan J, Mackie K, Pickel VM. Prefrontal cortical distribution of muscarinic M2 and cannabinoid-1 (CB1) receptors in adult male mice with or without chronic adolescent exposure to Δ9-tetrahydrocannabinol. Cereb Cortex 2022; 32:5420-5437. [PMID: 35151230 PMCID: PMC9712711 DOI: 10.1093/cercor/bhac024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 12/27/2022] Open
Abstract
Chronic adolescent administration of marijuana's major psychoactive compound, ∆9-tetrahydrocannabinol (Δ9-THC), produces adaptive changes in adult social and cognitive functions sustained by prelimbic prefrontal cortex (PL-PFC). Memory and learning processes in PL-PFC neurons can be regulated through cholinergic muscarinic-2 receptors (M2R) and modulated by activation of cannabinoid-1 receptors (CB1Rs) targeted by Δ9-THC. Thus, chronic exposure to Δ9-THC during adolescence may alter the expression and/or distribution of M2Rs in PL-PFC neurons receiving CB1R terminals. We tested this hypothesis by using electron microscopic dual CB1R and M2R immunolabeling in adult C57BL/6 J male mice that had received vehicle or escalating dose of Δ9-THC through adolescence. In vehicle controls, CB1R immunolabeling was mainly localized to axonal profiles virtually devoid of M2R but often apposing M2R-immunoreactive dendrites and dendritic spines. The dendrites received inputs from CB1R-labeled or unlabeled terminals, whereas spines received asymmetric synapses exclusively from axon terminals lacking CB1Rs. Adolescent Δ9-THC significantly increased plasmalemmal M2R-immunogold density exclusively in large dendrites receiving input from CB1R-labeled terminals. In contrast, cytoplasmic M2R-immunogold density decreased in small spines of the Δ9-THC-treated adult mice. We conclude that Δ9-THC engagement of CB1Rs during adolescence increases M2R plasmalemmal accumulation in large proximal dendrites and decreases M2R cytoplasmic expression in small spines of PL-PFC.
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Affiliation(s)
- Miguel Garzón
- Corresponding author: Department of Anatomy, Histology and Neuroscience, Medical School, Autónoma University of Madrid, Arzobispo Morcillo 4, 28029 Madrid, Spain.
| | - June Chan
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
| | - Ken Mackie
- Linda and Jack Gill Center for Biomolecular Science, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | - Virginia M Pickel
- Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, 407 East 61st Street, New York, NY 10065, USA
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21
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Wichmann C, Kuner T. Heterogeneity of glutamatergic synapses: cellular mechanisms and network consequences. Physiol Rev 2022; 102:269-318. [PMID: 34727002 DOI: 10.1152/physrev.00039.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chemical synapses are commonly known as a structurally and functionally highly diverse class of cell-cell contacts specialized to mediate communication between neurons. They represent the smallest "computational" unit of the brain and are typically divided into excitatory and inhibitory as well as modulatory categories. These categories are subdivided into diverse types, each representing a different structure-function repertoire that in turn are thought to endow neuronal networks with distinct computational properties. The diversity of structure and function found among a given category of synapses is referred to as heterogeneity. The main building blocks for this heterogeneity are synaptic vesicles, the active zone, the synaptic cleft, the postsynaptic density, and glial processes associated with the synapse. Each of these five structural modules entails a distinct repertoire of functions, and their combination specifies the range of functional heterogeneity at mammalian excitatory synapses, which are the focus of this review. We describe synapse heterogeneity that is manifested on different levels of complexity ranging from the cellular morphology of the pre- and postsynaptic cells toward the expression of different protein isoforms at individual release sites. We attempt to define the range of structural building blocks that are used to vary the basic functional repertoire of excitatory synaptic contacts and discuss sources and general mechanisms of synapse heterogeneity. Finally, we explore the possible impact of synapse heterogeneity on neuronal network function.
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Affiliation(s)
- Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Institute for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg, Germany
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22
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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: 21] [Impact Index Per Article: 7.0] [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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23
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Maksymetz J, Byun NE, Luessen DJ, Li B, Barry RL, Gore JC, Niswender CM, Lindsley CW, Joffe ME, Conn PJ. mGlu 1 potentiation enhances prelimbic somatostatin interneuron activity to rescue schizophrenia-like physiological and cognitive deficits. Cell Rep 2021; 37:109950. [PMID: 34731619 PMCID: PMC8628371 DOI: 10.1016/j.celrep.2021.109950] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 08/09/2021] [Accepted: 10/14/2021] [Indexed: 01/03/2023] Open
Abstract
Evidence for prefrontal cortical (PFC) GABAergic dysfunction is one of the most consistent findings in schizophrenia and may contribute to cognitive deficits. Recent studies suggest that the mGlu1 subtype of metabotropic glutamate receptor regulates cortical inhibition; however, understanding the mechanisms through which mGlu1 positive allosteric modulators (PAMs) regulate PFC microcircuit function and cognition is essential for advancing these potential therapeutics toward the clinic. We report a series of electrophysiology, optogenetic, pharmacological magnetic resonance imaging, and animal behavior studies demonstrating that activation of mGlu1 receptors increases inhibitory transmission in the prelimbic PFC by selective excitation of somatostatin-expressing interneurons (SST-INs). An mGlu1 PAM reverses cortical hyperactivity and concomitant cognitive deficits induced by N-methyl-d-aspartate (NMDA) receptor antagonists. Using in vivo optogenetics, we show that prelimbic SST-INs are necessary for mGlu1 PAM efficacy. Collectively, these findings suggest that mGlu1 PAMs could reverse cortical GABAergic deficits and exhibit efficacy in treating cognitive dysfunction in schizophrenia.
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Affiliation(s)
- James Maksymetz
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Nellie E Byun
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Deborah J Luessen
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Brianna Li
- Vanderbilt University, Nashville, TN 37232, USA
| | - Robert L Barry
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Radiology & Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232, USA
| | - Colleen M Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA
| | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Max E Joffe
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - P Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA; Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, USA.
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24
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Petralia RS, Wang YX. Review of Post-embedding Immunogold Methods for the Study of Neuronal Structures. Front Neuroanat 2021; 15:763427. [PMID: 34720893 PMCID: PMC8551803 DOI: 10.3389/fnana.2021.763427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 09/28/2021] [Indexed: 01/03/2023] Open
Abstract
The post-embedding immunogold (PI) technique for immunolabeling of neuronal tissues utilizing standard thin-section transmission electron microscopy (TEM) continues to be a prime method for understanding the functional localization of key proteins in neuronal function. Its main advantages over other immunolabeling methods for thin-section TEM are (1) fairly accurate and quantifiable localization of proteins in cells; (2) double-labeling of sections using two gold particle sizes; and (3) the ability to perform multiple labeling for different proteins by using adjacent sections. Here we first review in detail a common method for PI of neuronal tissues. This method has two major parts. First, we describe the freeze-substitution embedding method: cryoprotected tissue is frozen in liquid propane via plunge-freezing, and is placed in a freeze-substitution instrument in which the tissue is embedded in Lowicryl at low temperatures. We highlight important aspects of freeze-substitution embedding. Then we outline how thin sections of embedded tissue on grids are labeled with a primary antibody and a secondary gold particle-conjugated antibody, and the particular problems encountered in TEM of PI-labeled sections. In the Discussion, we compare our method both to earlier PI methods and to more recent PI methods used by other laboratories. We also compare TEM immunolabeling using PI vs. various pre-embedding immunolabeling methods, especially relating to neuronal tissue.
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Affiliation(s)
- Ronald S. Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, United States
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25
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Zieger HL, Choquet D. Nanoscale synapse organization and dysfunction in neurodevelopmental disorders. Neurobiol Dis 2021; 158:105453. [PMID: 34314857 DOI: 10.1016/j.nbd.2021.105453] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/18/2021] [Accepted: 07/21/2021] [Indexed: 12/20/2022] Open
Abstract
Neurodevelopmental disorders such as those linked to intellectual disabilities or autism spectrum disorder are thought to originate in part from genetic defects in synaptic proteins. Single gene mutations linked to synapse dysfunction can broadly be separated in three categories: disorders of transcriptional regulation, disorders of synaptic signaling and disorders of synaptic scaffolding and structures. The recent developments in super-resolution imaging technologies and their application to synapses have unraveled a complex nanoscale organization of synaptic components. On the one hand, part of receptors, adhesion proteins, ion channels, scaffold elements and the pre-synaptic release machinery are partitioned in subsynaptic nanodomains, and the respective organization of these nanodomains has tremendous impact on synaptic function. For example, pre-synaptic neurotransmitter release sites are partly aligned with nanometer precision to postsynaptic receptor clusters. On the other hand, a large fraction of synaptic components is extremely dynamic and constantly exchanges between synaptic domains and extrasynaptic or intracellular compartments. It is largely the combination of the exquisitely precise nanoscale synaptic organization of synaptic components and their high dynamic that allows the rapid and profound regulation of synaptic function during synaptic plasticity processes that underlie adaptability of brain function, learning and memory. It is very tempting to speculate that genetic defects that lead to neurodevelopmental disorders and target synaptic scaffolds and structures mediate their deleterious impact on brain function through perturbing synapse nanoscale dynamic organization. We discuss here how applying super-resolution imaging methods in models of neurodevelopmental disorders could help in addressing this question.
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Affiliation(s)
- Hanna L Zieger
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Daniel Choquet
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France; Univ. Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, F-33000 Bordeaux, France.
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26
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Burada AP, Vinnakota R, Lambolez B, Tricoire L, Kumar J. Structural biology of ionotropic glutamate delta receptors and their crosstalk with metabotropic glutamate receptors. Neuropharmacology 2021; 196:108683. [PMID: 34181979 DOI: 10.1016/j.neuropharm.2021.108683] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/31/2021] [Accepted: 06/17/2021] [Indexed: 10/21/2022]
Abstract
Enigmatic orphan glutamate delta receptors (GluD) are one of the four classes of the ionotropic glutamate receptors (iGluRs) that play key roles in synaptic transmission and plasticity. While members of other iGluR families viz AMPA, NMDA, and kainate receptors are gated by glutamate, the GluD receptors neither bind glutamate nor evoke ligand-induced currents upon binding of glycine and D-serine. Thus, the GluD receptors were considered to function as structural proteins that facilitate the formation, maturation, and maintenance of synapses in the hippocampus and cerebellum. Recent work has revealed that GluD receptors have extensive crosstalk with metabotropic glutamate receptors (mGlus) and are also gated by their activation. The latest development of a novel optopharamcological tool and the cryoEM structures of GluD receptors would help define the molecular and chemical basis of the GluD receptor's role in synaptic physiology. This article is part of the special Issue on "Glutamate Receptors - Orphan iGluRs".
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Affiliation(s)
- Ananth Prasad Burada
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India
| | - Rajesh Vinnakota
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India
| | - Bertrand Lambolez
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), CNRS, INSERM, Sorbonne Université, Paris, France
| | - Ludovic Tricoire
- Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), CNRS, INSERM, Sorbonne Université, Paris, France.
| | - Janesh Kumar
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University, Pune, Maharashtra, 411007, India.
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27
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Zuena AR, Casolini P, Venerosi A, Alemà GS, Nicoletti F, Calamandrei G. Selective reduction in the expression of type-1 metabotropic glutamate receptors in the hippocampus of adult rats born by caesarean section. Int J Dev Neurosci 2021; 81:333-341. [PMID: 33759234 DOI: 10.1002/jdn.10105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/23/2021] [Accepted: 03/18/2021] [Indexed: 11/12/2022] Open
Abstract
Perinatal hypoxia causes long-term neurobiological consequences, including alterations in mechanisms of activity-dependent synaptic plasticity and cognitive dysfunction. Changes in neurotransmitter receptors have been associated with these alterations, but little is known on how early hypoxia influences the expression and function of metabotropic glutamate (mGlu) receptors in adult life. This is an important issue because mGlu receptors are implicated in mechanisms of synaptic plasticity. Here, we examined the expression of mGlu1, mGlu5, and mGlu2/3 receptor subtypes in the hippocampus, nucleus accumbens, prefrontal cortex, and dorsal striatum in 6-month old Wistar rats (a) born by vaginal delivery; (b) born by caesarean section; and (c) born by caesarean section followed by 20 min of asphyxia. Unexpectedly, we found a large reduction of mGlu1α protein levels in the hippocampus of rats born by caesarean section regardless of the presence of asphyxia. No changes in mGlu1α receptor protein levels were found in the other brain regions. Levels of mGlu5 and mGlu2/3 receptors and levels of GluA2/3 and GluN1 subunits of AMPA and NMDA receptors did not differ among the three groups of rats in any brain region. These results are consistent with previous findings showing that changes in mGlu1 receptors occur within the epigenetic programming caused by early-life events.
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Affiliation(s)
- Anna Rita Zuena
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Paola Casolini
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Aldina Venerosi
- Centre for Behavioural Science and Mental Health, Istituto Superiore di Sanita, Roma, Italy
| | | | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,I.R.C.C.S. Neuromed, Pozzilli, Italy
| | - Gemma Calamandrei
- Centre for Behavioural Science and Mental Health, Istituto Superiore di Sanita, Roma, Italy
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28
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Brymer KJ, Barnes JR, Parsons MP. Entering a new era of quantifying glutamate clearance in health and disease. J Neurosci Res 2021; 99:1598-1617. [PMID: 33618436 DOI: 10.1002/jnr.24810] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/22/2021] [Accepted: 02/01/2021] [Indexed: 12/21/2022]
Abstract
Glutamate transporter proteins, expressed on both neurons and glia, serve as the main gatekeepers that dictate the spatial and temporal actions of extracellular glutamate. Glutamate is essential to the function of the healthy brain yet paradoxically contributes to the toxicity associated with many neurodegenerative diseases. Rapid transporter-mediated glutamate uptake, primarily occurring at astrocytic processes, tightens the efficiency of excitatory network activity and prevents toxic glutamate build-up in the extracellular space. Glutamate transporter dysfunction is thought to underlie myriad central nervous system (CNS) diseases including Alzheimer and Huntington disease. Over the past few decades, techniques such as biochemical uptake assays and electrophysiological recordings of transporter currents from individual astrocytes have revealed the remarkable ability of the CNS to efficiently clear extracellular glutamate. In more recent years, the rapidly evolving glutamate-sensing "sniffers" now allow researchers to visualize real-time glutamate transients on a millisecond time scale with single synapse spatial resolution in defined cell populations. As we transition to an increased reliance on optical-based methods of glutamate visualization and quantification, it is of utmost importance to understand not only the advantages that glutamate biosensors bring to the table but also the associated caveats and their implications for data interpretation. In this review, we summarize the strengths and limitations of the commonly used methods to quantify glutamate uptake. We then discuss what these techniques, when viewed as a complementary whole, have told us about the brain's ability to regulate glutamate levels, in both health and in the context of neurodegenerative disease.
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Affiliation(s)
- Kyle J Brymer
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Jocelyn R Barnes
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Matthew P Parsons
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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29
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Beppu K, Kubo N, Matsui K. Glial amplification of synaptic signals. J Physiol 2021; 599:2085-2102. [PMID: 33527421 DOI: 10.1113/jp280857] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/27/2021] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Recent studies have repeatedly demonstrated the cross-talk of heterogeneous signals between neuronal and glial circuits. Here, we investigated the mechanism and the influence of physiological interactions between neurons and glia in the cerebellum. We found that the cerebellar astrocytes, Bergmann glial cells, react to exogenously applied glutamate, glutamate transporter substrate (d-aspartate) and synaptically released glutamate. In response, the Bergmann glial cells release glutamate through volume-regulated anion channels. It is generally assumed that all of the postsynaptic current is mediated by presynaptically released glutamate. However, we showed that a part of the postsynaptic current is mediated by glutamate released from Bergmann glial cells. Optogenetic manipulation of Bergmann glial state with archaerhodpsin-T or channelrhodopsin-2 reduced or augmented the amount of glial glutamate release, respectively. Our data indicate that glutamate-induced glutamate release in Bergmann glia serves as an effective amplifier of excitatory information processing in the brain. ABSTRACT Transmitter released from presynaptic neurons has been considered to be the sole generator of postsynaptic excitatory signals. However, astrocytes of the glial cell population have also been shown to release transmitter that can react on postsynaptic receptors. Therefore, we investigated whether astrocytes take part in generation of at least a part of the synaptic current. In this study, mice cerebellar acute slices were prepared and whole cell patch clamp recordings were performed. We found that Bergmann glial cells (BGs), a type of astrocyte in the cerebellum, reacts to a glutamate transporter substrate, d-aspartate (d-Asp) and an anion conductance is generated and glutamate is released from the BGs. Glutamate release was attenuated or augmented by modulating the state of BGs with activation of light-sensitive proteins, archaerhodopsin-T (ArchT) or channelrhodopsin-2 (ChR2) expressed on BGs, respectively. Glutamate release appears to be mediated by anion channels that can be blocked by a volume-regulated anion channel-specific blocker. Synaptic response to a train of parallel fibre stimulation was recorded from Purkinje cells. The latter part of the response was also attenuated or augmented by glial modulation with ArchT or ChR2, respectively. Thus, BGs effectively function as an excitatory signal amplifier, and a part of the 'synaptic' current is actually mediated by glutamate released from BGs. These data show that the state of BGs have potential for having direct and fundamental consequences on the functioning of information processing in the brain.
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Affiliation(s)
- Kaoru Beppu
- Division of Interdisciplinary Medical Science, Center for Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, 980-8575, Japan
| | - Naoko Kubo
- Division of Interdisciplinary Medical Science, Center for Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, 980-8575, Japan
| | - Ko Matsui
- Division of Interdisciplinary Medical Science, Center for Neuroscience, Graduate School of Medicine, Tohoku University, Sendai, 980-8575, Japan.,Super-network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
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30
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Alkadhi KA. NMDA receptor-independent LTP in mammalian nervous system. Prog Neurobiol 2021; 200:101986. [PMID: 33400965 DOI: 10.1016/j.pneurobio.2020.101986] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/16/2020] [Accepted: 12/28/2020] [Indexed: 11/17/2022]
Abstract
Long-term potentiation (LTP) of synaptic transmission is a form of activity-dependent synaptic plasticity that exists at most synapses in the nervous system. In the central nervous system (CNS), LTP has been recorded at numerous synapses and is a prime candidate mechanism associating activity-dependent plasticity with learning and memory. LTP involves long-lasting increase in synaptic strength with various underlying mechanisms. In the CNS, the predominant type of LTP is believed to be dependent on activation of the ionotropic glutamate N-methyl-D-aspartate receptor (NMDAR), which is highly calcium-permeable. However, various forms of NMDAR-independent LTP have been identified in diverse areas of the nervous system. The NMDAR-independent LTP may require activation of glutamate metabotropic receptors (mGluR) or ionotropic receptors other than NMDAR such as nicotinic acetylcholine receptor (α7-nAChR), serotonin 5-HT3 receptor or calcium-permeable AMPA receptor (CP-AMPAR). In this review, NMDAR-independent LTP of various areas of the central and peripheral nervous systems are discussed.
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Affiliation(s)
- Karim A Alkadhi
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX, 77204, USA.
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31
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Crunelli V, Lőrincz ML, McCafferty C, Lambert RC, Leresche N, Di Giovanni G, David F. Clinical and experimental insight into pathophysiology, comorbidity and therapy of absence seizures. Brain 2020; 143:2341-2368. [PMID: 32437558 PMCID: PMC7447525 DOI: 10.1093/brain/awaa072] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/19/2019] [Accepted: 01/31/2020] [Indexed: 12/24/2022] Open
Abstract
Absence seizures in children and teenagers are generally considered relatively benign because of their non-convulsive nature and the large incidence of remittance in early adulthood. Recent studies, however, show that 30% of children with absence seizures are pharmaco-resistant and 60% are affected by severe neuropsychiatric comorbid conditions, including impairments in attention, cognition, memory and mood. In particular, attention deficits can be detected before the epilepsy diagnosis, may persist even when seizures are pharmacologically controlled and are aggravated by valproic acid monotherapy. New functional MRI-magnetoencephalography and functional MRI-EEG studies provide conclusive evidence that changes in blood oxygenation level-dependent signal amplitude and frequency in children with absence seizures can be detected in specific cortical networks at least 1 min before the start of a seizure, spike-wave discharges are not generalized at seizure onset and abnormal cortical network states remain during interictal periods. From a neurobiological perspective, recent electrical recordings and imaging of large neuronal ensembles with single-cell resolution in non-anaesthetized models show that, in contrast to the predominant opinion, cortical mechanisms, rather than an exclusively thalamic rhythmogenesis, are key in driving seizure ictogenesis and determining spike-wave frequency. Though synchronous ictal firing characterizes cortical and thalamic activity at the population level, individual cortico-thalamic and thalamocortical neurons are sparsely recruited to successive seizures and consecutive paroxysmal cycles within a seizure. New evidence strengthens previous findings on the essential role for basal ganglia networks in absence seizures, in particular the ictal increase in firing of substantia nigra GABAergic neurons. Thus, a key feature of thalamic ictogenesis is the powerful increase in the inhibition of thalamocortical neurons that originates at least from two sources, substantia nigra and thalamic reticular nucleus. This undoubtedly provides a major contribution to the ictal decrease in total firing and the ictal increase of T-type calcium channel-mediated burst firing of thalamocortical neurons, though the latter is not essential for seizure expression. Moreover, in some children and animal models with absence seizures, the ictal increase in thalamic inhibition is enhanced by the loss-of-function of the astrocytic GABA transporter GAT-1 that does not necessarily derive from a mutation in its gene. Together, these novel clinical and experimental findings bring about paradigm-shifting views of our understanding of absence seizures and demand careful choice of initial monotherapy and continuous neuropsychiatric evaluation of affected children. These issues are discussed here to focus future clinical and experimental research and help to identify novel therapeutic targets for treating both absence seizures and their comorbidities.
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Affiliation(s)
- Vincenzo Crunelli
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK
| | - Magor L Lőrincz
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK.,Department of Physiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Physiology, Anatomy and Neuroscience, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Cian McCafferty
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Régis C Lambert
- Sorbonne Université, CNRS, INSERM, Neuroscience Paris Seine and Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Nathalie Leresche
- Sorbonne Université, CNRS, INSERM, Neuroscience Paris Seine and Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Giuseppe Di Giovanni
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK
| | - François David
- Cerebral dynamics, learning and plasticity, Integrative Neuroscience and Cognition Center - UMR 8002, Paris, France
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32
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Long-term potentiation of glycinergic synapses by semi-natural stimulation patterns during tonotopic map refinement. Sci Rep 2020; 10:16899. [PMID: 33037263 PMCID: PMC7547119 DOI: 10.1038/s41598-020-73050-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 09/10/2020] [Indexed: 12/22/2022] Open
Abstract
Before the onset of hearing, cochlea-generated patterns of spontaneous spike activity drive the maturation of central auditory circuits. In the glycinergic sound localization pathway from the medial nucleus of the trapezoid body (MNTB) to the lateral superior olive (LSO) this spontaneous activity guides the strengthening and silencing of synapses which underlies tonotopic map refinement. However, the mechanisms by which patterned activity regulates synaptic refinement in the MNTB-LSO pathway are still poorly understood. To address this question, we recorded from LSO neurons in slices from prehearing mice while stimulating MNTB afferents with stimulation patterns that mimicked those present in vivo. We found that these semi-natural stimulation patterns reliably elicited a novel form of long-term potentiation (LTP) of MNTB-LSO synapses. Stimulation patterns that lacked the characteristic high-frequency (200 Hz) component of prehearing spike activity failed to elicit potentiation. LTP was calcium dependent, required the activation of both g-protein coupled GABAB and metabotropic glutamate receptors and involved an increase in postsynaptic glycine receptor-mediated currents. Our results provide a possible mechanism linking spontaneous spike bursts to tonotopic map refinement and further highlight the importance of the co-release of GABA and glutamate from immature glycinergic MNTB terminals.
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33
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Canepari M. Is Purkinje Neuron Hyperpolarisation Important for Cerebellar Synaptic Plasticity? A Retrospective and Prospective Analysis. THE CEREBELLUM 2020; 19:869-878. [PMID: 32654026 DOI: 10.1007/s12311-020-01164-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two recent studies have demonstrated that the dendritic Ca2+ signal associated with a climbing fibre (CF) input to the cerebellar Purkinje neuron (PN) depends on the membrane potential (Vm). Specifically, when the cell is hyperpolarised, this signal is mediated by T-type voltage-gated Ca2+ channels; in contrast, when the cell is firing, the CF-PN signal is mediated by P/Q-type voltage-gated Ca2+ channels. When the CF input is paired with parallel fibre (PF) activity, the signal is locally amplified at the sites of PF-activated synapses according to the Vm at the time of the CF input, suggesting that the standing Vm is a critical parameter for the induction of PF synaptic plasticity. In this review, I analyse how the Vm can potentially play a role in cerebellar learning focussing, in particular, on the hyperpolarised state that appears to occur episodically, since PNs are mostly firing under physiological conditions. By revisiting the recent literature reporting in vivo recordings and synaptic plasticity studies, I speculate on how a putative role of the PN Vm can provide an interpretation for the results of these studies.
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Affiliation(s)
- Marco Canepari
- University of Grenoble Alpes, CNRS, LIPhy, F-38000, Grenoble, France. .,Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France. .,Institut National de la Santé et Recherche Médicale, Paris, France.
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34
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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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35
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Role of the TRPC1 Channel in Hippocampal Long-Term Depression and in Spatial Memory Extinction. Int J Mol Sci 2020; 21:ijms21051712. [PMID: 32138218 PMCID: PMC7084652 DOI: 10.3390/ijms21051712] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/21/2020] [Accepted: 02/27/2020] [Indexed: 12/19/2022] Open
Abstract
Group I metabotropic glutamate receptors (mGluR) are involved in various forms of synaptic plasticity that are believed to underlie declarative memory. We previously showed that mGluR5 specifically activates channels containing TRPC1, an isoform of the canonical family of Transient Receptor Potential channels highly expressed in the CA1-3 regions of the hippocampus. Using a tamoxifen-inducible conditional knockout model, we show here that the acute deletion of the Trpc1 gene alters the extinction of spatial reference memory. mGluR-induced long-term depression, which is partially responsible for memory extinction, was impaired in these mice. Similar results were obtained in vitro and in vivo by inhibiting the channel by its most specific inhibitor, Pico145. Among the numerous known postsynaptic pathways activated by type I mGluR, we observed that the deletion of Trpc1 impaired the activation of ERK1/2 and the subsequent expression of Arc, an immediate early gene that plays a key role in AMPA receptors endocytosis and subsequent long-term depression.
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36
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Booker SA, Harada H, Elgueta C, Bank J, Bartos M, Kulik A, Vida I. Presynaptic GABA B receptors functionally uncouple somatostatin interneurons from the active hippocampal network. eLife 2020; 9:51156. [PMID: 32073397 PMCID: PMC7060044 DOI: 10.7554/elife.51156] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/18/2020] [Indexed: 01/04/2023] Open
Abstract
Information processing in cortical neuronal networks relies on properly balanced excitatory and inhibitory neurotransmission. A ubiquitous motif for maintaining this balance is the somatostatin interneuron (SOM-IN) feedback microcircuit. Here, we investigated the modulation of this microcircuit by presynaptic GABAB receptors (GABABRs) in the rodent hippocampus. Whole-cell recordings from SOM-INs revealed that both excitatory and inhibitory synaptic inputs are strongly inhibited by GABABRs, while optogenetic activation of the interneurons shows that their inhibitory output is also strongly suppressed. Electron microscopic analysis of immunogold-labelled freeze-fracture replicas confirms that GABABRs are highly expressed presynaptically at both input and output synapses of SOM-INs. Activation of GABABRs selectively suppresses the recruitment of SOM-INs during gamma oscillations induced in vitro. Thus, axonal GABABRs are positioned to efficiently control the input and output synapses of SOM-INs and can functionally uncouple them from local network with implications for rhythmogenesis and the balance of entorhinal versus intrahippocampal afferents.
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Affiliation(s)
- Sam A Booker
- Institute for Integrative Neuroanatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Harumi Harada
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Claudio Elgueta
- Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Julia Bank
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Marlene Bartos
- Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Akos Kulik
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Imre Vida
- Institute for Integrative Neuroanatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Kougioumoutzakis A, Pelletier JG, Laplante I, Khlaifia A, Lacaille JC. TRPC1 mediates slow excitatory synaptic transmission in hippocampal oriens/alveus interneurons. Mol Brain 2020; 13:12. [PMID: 31996247 PMCID: PMC6988362 DOI: 10.1186/s13041-020-0558-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/21/2020] [Indexed: 12/31/2022] Open
Abstract
Hippocampal GABAergic interneurons play key roles in regulating principal cell activity and plasticity. Interneurons located in stratum oriens/alveus (O/A INs) receive excitatory inputs from CA1 pyramidal cells and express a Hebbian form of long-term potentiation (LTP) at their excitatory input synapses. This LTP requires the activation of metabotropic glutamate receptors 1a (mGluR1a) and Ca2+ entry via transient receptor potential (TRP) channels. However, the type of TRP channels involved in synaptic transmission at these synapses remains largely unknown. Using patch-clamp recordings, we show that slow excitatory postsynaptic currents (EPSCs) evoked in O/A INs are dependent on TRP channels but may be independent of phospholipase C. Using reverse transcription polymerase chain reaction (RT-PCR) we found that mRNA for TRPC 1, 3–7 was present in CA1 hippocampus. Using single-cell RT-PCR, we found expression of mRNA for TRPC 1, 4–7, but not TRPC3, in O/A INs. Using co-immunoprecipitation assays in HEK-293 cell expression system, we found that TRPC1 and TRPC4 interacted with mGluR1a. Co-immunoprecipitation in hippocampus showed that TRPC1 interacted with mGluR1a. Using immunofluorescence, we found that TRPC1 co-localized with mGluR1a in O/A IN dendrites, whereas TRPC4 localization appeared limited to O/A IN cell body. Down-regulation of TRPC1, but not TRPC4, expression in O/A INs using small interfering RNAs prevented slow EPSCs, suggesting that TRPC1 is an obligatory TRPC subunit for these EPSCs. Our findings uncover a functional role of TRPC1 in mGluR1a-mediated slow excitatory synaptic transmission onto O/A INs that could be involved in Hebbian LTP at these synapses.
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Affiliation(s)
- André Kougioumoutzakis
- Department of Neurosciences and GRSNC, Université de Montréal, P.O. Box 6128, Station Downtown, Montreal, Montreal, QC, H3C 3J7, Canada
| | - Joe Guillaume Pelletier
- Department of Neurosciences and GRSNC, Université de Montréal, P.O. Box 6128, Station Downtown, Montreal, Montreal, QC, H3C 3J7, Canada
| | - Isabel Laplante
- Department of Neurosciences and GRSNC, Université de Montréal, P.O. Box 6128, Station Downtown, Montreal, Montreal, QC, H3C 3J7, Canada
| | - Abdessattar Khlaifia
- Department of Neurosciences and GRSNC, Université de Montréal, P.O. Box 6128, Station Downtown, Montreal, Montreal, QC, H3C 3J7, Canada
| | - Jean-Claude Lacaille
- Department of Neurosciences and GRSNC, Université de Montréal, P.O. Box 6128, Station Downtown, Montreal, Montreal, QC, H3C 3J7, Canada.
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Griego E, Galván EJ. Metabotropic Glutamate Receptors at the Aged Mossy Fiber - CA3 Synapse of the Hippocampus. Neuroscience 2020; 456:95-105. [PMID: 31917351 DOI: 10.1016/j.neuroscience.2019.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/28/2022]
Abstract
Metabotropic glutamate receptors (mGluRs) are a group of G-protein-coupled receptors that exert a broad array of modulatory actions at excitatory synapses of the central nervous system. In the hippocampus, the selective activation of the different mGluRs modulates the intrinsic excitability, the strength of synaptic transmission, and induces multiple forms of long-term plasticity. Despite the relevance of mGluRs in the normal function of the hippocampus, we know very little about the changes that mGluRs functionality undergoes during the non-pathological aging. Here, we review data concerning the physiological actions of mGluRs, with particular emphasis on hippocampal area CA3. Later, we examine changes in the expression and functionality of mGluRs during the aging process. We complement this review with original data showing an array of electrophysiological modifications observed in the synaptic transmission and intrinsic excitability of aged CA3 pyramidal cells in response to the pharmacological stimulation of the different mGluRs.
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Affiliation(s)
- Ernesto Griego
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico
| | - Emilio J Galván
- Departamento de Farmacobiología, Cinvestav Sede Sur, México City, Mexico.
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Prestori F, Mapelli L, D'Angelo E. Diverse Neuron Properties and Complex Network Dynamics in the Cerebellar Cortical Inhibitory Circuit. Front Mol Neurosci 2019; 12:267. [PMID: 31787879 PMCID: PMC6854908 DOI: 10.3389/fnmol.2019.00267] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/17/2019] [Indexed: 12/12/2022] Open
Abstract
Neuronal inhibition can be defined as a spatiotemporal restriction or suppression of local microcircuit activity. The importance of inhibition relies in its fundamental role in shaping signal processing in single neurons and neuronal circuits. In this context, the activity of inhibitory interneurons proved the key to endow networks with complex computational and dynamic properties. In the last 50 years, the prevailing view on the functional role of cerebellar cortical inhibitory circuits was that excitatory and inhibitory inputs sum spatially and temporally in order to determine the motor output through Purkinje cells (PCs). Consequently, cerebellar inhibition has traditionally been conceived in terms of restricting or blocking excitation. This assumption has been challenged, in particular in the cerebellar cortex where all neurons except granule cells (and unipolar brush cells in specific lobules) are inhibitory and fire spontaneously at high rates. Recently, a combination of electrophysiological recordings in vitro and in vivo, imaging, optogenetics and computational modeling, has revealed that inhibitory interneurons play a much more complex role in regulating cerebellar microcircuit functions: inhibition shapes neuronal response dynamics in the whole circuit and eventually regulate the PC output. This review elaborates current knowledge on cerebellar inhibitory interneurons [Golgi cells, Lugaro cells (LCs), basket cells (BCs) and stellate cells (SCs)], starting from their ontogenesis and moving up to their morphological, physiological and plastic properties, and integrates this knowledge with that on the more renown granule cells and PCs. We will focus on the circuit loops in which these interneurons are involved and on the way they generate feed-forward, feedback and lateral inhibition along with complex spatio-temporal response dynamics. In this perspective, inhibitory interneurons emerge as the real controllers of cerebellar functioning.
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Affiliation(s)
- Francesca Prestori
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Lisa Mapelli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D'Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,IRCCS Mondino Foundation, Pavia, Italy
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40
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Expression of type I mGluRs predicts plasticity in the hippocampal stratum radiatum interneurons. Neurosci Lett 2019; 712:134472. [PMID: 31499135 DOI: 10.1016/j.neulet.2019.134472] [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: 07/30/2019] [Revised: 08/27/2019] [Accepted: 08/29/2019] [Indexed: 11/23/2022]
Abstract
Changes in synaptic strength between hippocampal CA1 pyramidal cell synapses are partly responsible for memory acquisition. This plasticity is modulated by feedforward inhibitory interneurons in the stratum radiatum. While radiatum interneurons experience either long-term depression (LTD), short-term depression (STD), or lack plasticity, it is unclear whether plasticity correlates to specific interneuron subtypes. Using whole-cell electrophysiology and real-time quantitative PCR, we characterized the plasticity expressed by different interneuron subtypes. We first analyzed calcium binding proteins and cholecystokinin mRNA expression patterns to determine cell subtype. We then assessed endocannabinoid (eCB) biosynthetic enzyme mRNA expression, including diacylglycerol lipase α, N-acyl-phosphatidylethanolamine phospholipase D, and 12-lipoxygenase, and metabotropic glutamate receptors that often mediate plasticity. Neurons exhibiting LTD tended to co-express mRNA for at least one eCB biosynthetic enzyme and the metabotropic glutamate receptor 5 (mGluR5). Conversely, mGluR5 was not expressed by neurons exhibiting STD or no plasticity. Neurons that exhibited STD tended to express mRNA for at least one eCB biosynthetic enzyme and mGluR1, but not mGluR5. This suggests that plasticity of stratum radiatum interneurons could be predicted based on type I mGluR expression.
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41
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Winterer J, Lukacsovich D, Que L, Sartori AM, Luo W, Földy C. Single-cell RNA-Seq characterization of anatomically identified OLM interneurons in different transgenic mouse lines. Eur J Neurosci 2019; 50:3750-3771. [PMID: 31420995 PMCID: PMC6973274 DOI: 10.1111/ejn.14549] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 07/30/2019] [Accepted: 08/09/2019] [Indexed: 01/18/2023]
Abstract
Inhibitory GABAergic interneurons create different brain activity patterns that correlate with behavioural states. In this characterizing study, we used single-cell RNA-Seq to analyse anatomically- and electrophysiologically identified hippocampal oriens-lacunosum moleculare (OLM) interneurons. OLMs express somatostatin (Sst), generate feedback inhibition and play important roles in theta oscillations and fear encoding. Although an anatomically- and biophysically homogenous population, OLMs presumably comprise of two functionally distinct types with different developmental origins, inferred from the expression pattern of serotonin type-3a (5-HT3a, or Htr3a) receptor subunit and 5-HT excitability in a set of OLMs. To broadly characterize OLM cells, we used the Sst-Cre and the BAC transgenic Htr3a-Cre mouse lines and separately analysed SstCre-OLM and Htr3aCre-OLM types. We found a surprisingly consistent expression of Npy in OLMs, which was previously not associated with the identity of this type. Our analyses furthermore revealed uniform expression of developmental origin-related genes, including transcription factors and neurexin isoforms, without providing support for the current view that OLMs may originate from multiple neurogenic zones. Together, we found that OLMs constitute a highly homogenous transcriptomic population. Finally, our results revealed surprisingly infrequent expression of Htr3a in only ~10% of OLMs and an apparently specific expression of the 5-HT3b subunit-coding gene Htr3b in Htr3aCre-OLMs, but not in SstCre-OLMs. However, additional in situ hybridization experiments suggested that the differential expression of Htr3b may represent an unexpected consequence arising from the design of the Htr3a-Cre BAC transgenic line.
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Affiliation(s)
- Jochen Winterer
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Natural Sciences, University of Zürich, Zürich, Switzerland
| | - David Lukacsovich
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Natural Sciences, University of Zürich, Zürich, Switzerland
| | - Lin Que
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Natural Sciences, University of Zürich, Zürich, Switzerland
| | - Andrea M Sartori
- Institute for Regenerative Medicine, Department of Health Sciences and Technology, ETH Zürich, University of Zürich, Zürich, Switzerland
| | - Wenshu Luo
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Natural Sciences, University of Zürich, Zürich, Switzerland
| | - Csaba Földy
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Natural Sciences, University of Zürich, Zürich, Switzerland
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42
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Masilamoni GJ, Smith Y. Group I metabotropic glutamate receptors in the primate motor thalamus: subsynaptic association with cortical and sub-cortical glutamatergic afferents. Brain Struct Funct 2019; 224:2787-2804. [PMID: 31422483 DOI: 10.1007/s00429-019-01937-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 08/07/2019] [Indexed: 12/21/2022]
Abstract
Preclinical evidence indicates that mGluR5 is a potential therapeutic target for Parkinson's disease and L-DOPA-induced dyskinesia. However, the mechanisms through which these therapeutic benefits are mediated remain poorly understood. Although the regulatory role of mGluR5 on glutamatergic transmission has been examined in various basal ganglia nuclei, very little is known about the localization and function of mGluR5 in the ventral motor and intralaminar thalamic nuclei, the main targets of basal ganglia output in mammals. Thus, we used immuno-electron microscopy to map the cellular and subcellular localization of group I mGluRs (mGluR1a and mGluR5) in the ventral motor and caudal intralaminar thalamic nuclei in rhesus monkeys. Furthermore, using double immuno-electron microscopy, we examined the subsynaptic localization of mGluR5 in relation to cortical and sub-cortical glutamatergic afferents. Four major conclusions can be drawn from these data. First, mGluR1a and mGluR5 are expressed postsynaptically on the plasma membrane of dendrites of projection neurons and GABAergic interneurons in the basal ganglia- and cerebellar-receiving regions of the ventral motor thalamus and in CM. Second, the plasma membrane-bound mGluR5 immunoreactivity is preferentially expressed perisynaptically at the edges of cortical and sub-cortical glutamatergic afferents. Third, the mGluR5 immunoreactivity is more strongly expressed in the lateral than the medial tiers of CM, suggesting a preferential association with thalamocortical over thalamostriatal neurons in the primate CM. Overall, mGluR5 is located to subserve powerful modulatory role of cortical and subcortical glutamatergic transmission in the primate ventral motor thalamus and CM.
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Affiliation(s)
- Gunasingh Jeyaraj Masilamoni
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 30329, USA. .,Udall Center of Excellence for Parkinson's Disease, Emory University School of Medicine, Atlanta, GA, 30322, USA.
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA, 30329, USA.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Udall Center of Excellence for Parkinson's Disease, Emory University School of Medicine, Atlanta, GA, 30322, USA
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43
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Gonçalves-Ribeiro J, Pina CC, Sebastião AM, Vaz SH. Glutamate Transporters in Hippocampal LTD/LTP: Not Just Prevention of Excitotoxicity. Front Cell Neurosci 2019; 13:357. [PMID: 31447647 PMCID: PMC6691053 DOI: 10.3389/fncel.2019.00357] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/18/2019] [Indexed: 12/31/2022] Open
Abstract
Glutamate uptake is a process mediated by sodium-dependent glutamate transporters, preventing glutamate spillover from the synapse. Typically, astrocytes express higher amounts of glutamate transporters, thus being responsible for most of the glutamate uptake; nevertheless, neurons can also express these transporters, albeit in smaller concentrations. When not regulated, glutamate uptake can lead to neuronal death. Indeed, the majority of the studies regarding glutamate transporters have focused on excitotoxicity and the subsequent neuronal loss. However, later studies have found that glutamate uptake is not a static process, evincing a possible correlation between this phenomenon and the efficiency of synaptic transmission and plasticity. In this review, we will focus on the role of the increase in glutamate uptake that occurs during long-term potentiation (LTP) in the hippocampus, as well as on the impairment of long-term depression (LTD) under the same conditions. The mechanism underpinning the modulatory effect of glutamate transporters over synaptic plasticity still remains unascertained; yet, it appears to have a more prominent effect over the N-methyl-D-aspartate receptor (NMDAR), despite changes in other glutamate receptors may also occur.
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Affiliation(s)
- Joana Gonçalves-Ribeiro
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Carolina Campos Pina
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ana Maria Sebastião
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sandra Henriques Vaz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.,Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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44
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Hilscher MM, Nogueira I, Mikulovic S, Kullander K, Leão RN, Leão KE. Chrna2‐OLM interneurons display different membrane properties and h‐current magnitude depending on dorsoventral location. Hippocampus 2019; 29:1224-1237. [DOI: 10.1002/hipo.23134] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/03/2019] [Accepted: 06/08/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Markus M. Hilscher
- Brain InstituteFederal University of Rio Grande do Norte Natal Rio Grande do Norte Brazil
- Institute for Analysis and Scientific ComputingVienna University of Technology Vienna Austria
- Unit of Developmental Genetics, Department of NeuroscienceUppsala University Uppsala Sweden
| | - Ingrid Nogueira
- Brain InstituteFederal University of Rio Grande do Norte Natal Rio Grande do Norte Brazil
| | - Sanja Mikulovic
- Unit of Developmental Genetics, Department of NeuroscienceUppsala University Uppsala Sweden
| | - Klas Kullander
- Unit of Developmental Genetics, Department of NeuroscienceUppsala University Uppsala Sweden
| | - Richardson N. Leão
- Brain InstituteFederal University of Rio Grande do Norte Natal Rio Grande do Norte Brazil
- Unit of Developmental Genetics, Department of NeuroscienceUppsala University Uppsala Sweden
| | - Katarina E. Leão
- Brain InstituteFederal University of Rio Grande do Norte Natal Rio Grande do Norte Brazil
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45
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Galvan A, Raper J, Hu X, Paré JF, Bonaventura J, Richie CT, Michaelides M, Mueller SAL, Roseboom PH, Oler JA, Kalin NH, Hall RA, Smith Y. Ultrastructural localization of DREADDs in monkeys. Eur J Neurosci 2019; 50:2801-2813. [PMID: 31063250 DOI: 10.1111/ejn.14429] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/15/2019] [Accepted: 04/23/2019] [Indexed: 01/01/2023]
Abstract
Designer receptors exclusively activated by designer drugs (DREADDs) are extensively used to modulate neuronal activity in rodents, but their use in primates remains limited. An essential need that remains is the demonstration that DREADDs are efficiently expressed on the plasma membrane of primate neurons. To address this issue, electron microscopy immunogold was used to determine the subcellular localization of the AAV vector-induced DREADDs hM4Di and hM3Dq fused to different tags in various brain areas of rhesus monkeys and mice. When hM4Di was fused to mCherry, the immunogold labelling was mostly confined to the intracellular space, and poorly expressed at the plasma membrane in monkey dendrites. In contrast, the hM4Di-mCherry labelling was mostly localized to the dendritic plasma membrane in mouse neurons, suggesting species differences in the plasma membrane expression of these exogenous proteins. The lack of hM4Di plasma membrane expression may limit the functional effects of systemic administration of DREADD-actuators in monkey neurons. Removing the mCherry and fusing of hM4Di with the haemagglutinin (HA) tag resulted in strong neuronal plasma membrane immunogold labelling in both monkeys and mice neurons. Finally, hM3Dq-mCherry was expressed mostly at the plasma membrane in monkey neurons, indicating that the fusion of mCherry with hM3Dq does not hamper membrane incorporation of this specific DREADD. Our results suggest that the pattern of ultrastructural expression of DREADDs in monkey neurons depends on the DREADD/tag combination. Therefore, a preliminary characterization of plasma membrane expression of specific DREADD/tag combinations is recommended when using chemogenetic approaches in primates.
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Affiliation(s)
- Adriana Galvan
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia.,Department of Neurology, Emory University School of Medicine, Atlanta, Georgia
| | - Jessica Raper
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
| | - Xing Hu
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
| | - Jean-François Paré
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia
| | - Jordi Bonaventura
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse (NIDA), Intramural Research Program, National Institutes of Health, Baltimore, Maryland
| | - Christopher T Richie
- Genetic Engineering and Viral Vector Core, National Institute on Drug Abuse (NIDA), Intramural Research Program, National Institutes of Health, Baltimore, Maryland
| | - Michael Michaelides
- Biobehavioral Imaging and Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse (NIDA), Intramural Research Program, National Institutes of Health, Baltimore, Maryland.,Department of Psychiatry, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Sascha A L Mueller
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin.,Molecular and Cellular Pharmacology Training Program, University of Wisconsin, Madison, Wisconsin
| | | | - Jonathan A Oler
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin
| | - Ned H Kalin
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin.,Molecular and Cellular Pharmacology Training Program, University of Wisconsin, Madison, Wisconsin.,Wisconsin National Primate Research Center, Madison, Wisconsin
| | - Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia
| | - Yoland Smith
- Yerkes National Primate Research Center, Emory University, Atlanta, Georgia.,Department of Neurology, Emory University School of Medicine, Atlanta, Georgia
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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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47
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Dubovyk V, Manahan-Vaughan D. Distinct Time-Course of Alterations of Groups I and II Metabotropic Glutamate Receptor and GABAergic Receptor Expression Along the Dorsoventral Hippocampal Axis in an Animal Model of Psychosis. Front Behav Neurosci 2019; 13:98. [PMID: 31139061 PMCID: PMC6519509 DOI: 10.3389/fnbeh.2019.00098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/23/2019] [Indexed: 01/13/2023] Open
Abstract
Psychosis is a clinical state that encompasses a range of abnormal conditions, including distortions in sensory information processing and the resultant delusional thinking, emotional discordance and cognitive impairments. Upon developing this condition, the rate at which cognitive and behavioral deteriorations progress steadily increases suggesting an active contribution of the first psychotic event to the progression of structural and functional abnormalities and disease establishment in diagnosed patients. Changes in GABAergic and glutamatergic function, or expression, in the hippocampus have been proposed as a key factor in the pathophysiology of psychosis. However, little is known as to the time-point of onset of putative changes, to what extent they are progressive, and their relation to disease stabilization. Here, we characterized the expression and distribution patterns of groups I and II metabotropic glutamate (mGlu) receptors and GABA receptors 1 week and 3 months after systemic treatment with an N-methyl-D-aspartate receptor (NMDAR) antagonist (MK801) that is used to model a psychosis-like state in adult rats. We found an early alteration in the expression of mGlu1, mGlu2/3, and GABAB receptors across the hippocampal dorsoventral and transverse axes. This expanded to include an up-regulation of mGlu5 levels across the entire CA1 region and a reduction in GABAB expression, as well as GAD67-positive interneurons particularly in the dorsal hippocampus that appeared 3 months after treatment. Our findings indicate that a reduction of excitability may occur in the hippocampus soon after first-episode psychosis. This changes, over time, into increased excitability. These hippocampus-specific alterations are likely to contribute to the pathophysiology and stabilization of psychosis.
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Affiliation(s)
- Valentyna Dubovyk
- Department of Neurophysiology, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr-University Bochum, Bochum, Germany
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48
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Valtcheva S, Venance L. Control of Long-Term Plasticity by Glutamate Transporters. Front Synaptic Neurosci 2019; 11:10. [PMID: 31024287 PMCID: PMC6465798 DOI: 10.3389/fnsyn.2019.00010] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/12/2019] [Indexed: 12/11/2022] Open
Abstract
Activity-dependent long-term changes in synaptic strength constitute key elements for learning and memory formation. Long-term plasticity can be induced in vivo and ex vivo by various physiologically relevant activity patterns. Depending on their temporal statistics, such patterns can induce long-lasting changes in the synaptic weight by potentiating or depressing synaptic transmission. At excitatory synapses, glutamate uptake operated by excitatory amino acid transporters (EAATs) has a critical role in regulating the strength and the extent of receptor activation by afferent activity. EAATs tightly control synaptic transmission and glutamate spillover. EAATs activity can, therefore, determine the polarity and magnitude of long-term plasticity by regulating the spatiotemporal profile of the glutamate transients and thus, the glutamate access to pre- and postsynaptic receptors. Here, we summarize compelling evidence that EAATs regulate various forms of long-term synaptic plasticity and the consequences of such regulation for behavioral output. We speculate that experience-dependent plasticity of EAATs levels can determine the sensitivity of synapses to frequency- or time-dependent plasticity paradigms. We propose that EAATs contribute to the gating of relevant inputs eligible to induce long-term plasticity and thereby select the operating learning rules that match the physiological function of the synapse adapted to the behavioral context.
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Affiliation(s)
- Silvana Valtcheva
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR7241/INSERM U1050, Paris, France
| | - Laurent Venance
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR7241/INSERM U1050, Paris, France
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Martins NRB, Angelica A, Chakravarthy K, Svidinenko Y, Boehm FJ, Opris I, Lebedev MA, Swan M, Garan SA, Rosenfeld JV, Hogg T, Freitas RA. Human Brain/Cloud Interface. Front Neurosci 2019; 13:112. [PMID: 30983948 PMCID: PMC6450227 DOI: 10.3389/fnins.2019.00112] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/30/2019] [Indexed: 12/25/2022] Open
Abstract
The Internet comprises a decentralized global system that serves humanity's collective effort to generate, process, and store data, most of which is handled by the rapidly expanding cloud. A stable, secure, real-time system may allow for interfacing the cloud with the human brain. One promising strategy for enabling such a system, denoted here as a "human brain/cloud interface" ("B/CI"), would be based on technologies referred to here as "neuralnanorobotics." Future neuralnanorobotics technologies are anticipated to facilitate accurate diagnoses and eventual cures for the ∼400 conditions that affect the human brain. Neuralnanorobotics may also enable a B/CI with controlled connectivity between neural activity and external data storage and processing, via the direct monitoring of the brain's ∼86 × 109 neurons and ∼2 × 1014 synapses. Subsequent to navigating the human vasculature, three species of neuralnanorobots (endoneurobots, gliabots, and synaptobots) could traverse the blood-brain barrier (BBB), enter the brain parenchyma, ingress into individual human brain cells, and autoposition themselves at the axon initial segments of neurons (endoneurobots), within glial cells (gliabots), and in intimate proximity to synapses (synaptobots). They would then wirelessly transmit up to ∼6 × 1016 bits per second of synaptically processed and encoded human-brain electrical information via auxiliary nanorobotic fiber optics (30 cm3) with the capacity to handle up to 1018 bits/sec and provide rapid data transfer to a cloud based supercomputer for real-time brain-state monitoring and data extraction. A neuralnanorobotically enabled human B/CI might serve as a personalized conduit, allowing persons to obtain direct, instantaneous access to virtually any facet of cumulative human knowledge. Other anticipated applications include myriad opportunities to improve education, intelligence, entertainment, traveling, and other interactive experiences. A specialized application might be the capacity to engage in fully immersive experiential/sensory experiences, including what is referred to here as "transparent shadowing" (TS). Through TS, individuals might experience episodic segments of the lives of other willing participants (locally or remote) to, hopefully, encourage and inspire improved understanding and tolerance among all members of the human family.
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Affiliation(s)
- Nuno R. B. Martins
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Center for Research and Education on Aging (CREA), University of California, Berkeley and LBNL, Berkeley, CA, United States
| | | | - Krishnan Chakravarthy
- UC San Diego Health Science, San Diego, CA, United States
- VA San Diego Healthcare System, San Diego, CA, United States
| | | | | | - Ioan Opris
- Miami Project to Cure Paralysis, University of Miami, Miami, FL, United States
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States
| | - Mikhail A. Lebedev
- Center for Neuroengineering, Duke University, Durham, NC, United States
- Center for Bioelectric Interfaces of the Institute for Cognitive Neuroscience of the National Research University Higher School of Economics, Moscow, Russia
- Department of Information and Internet Technologies of Digital Health Institute, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Melanie Swan
- Department of Philosophy, Purdue University, West Lafayette, IN, United States
| | - Steven A. Garan
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States
- Center for Research and Education on Aging (CREA), University of California, Berkeley and LBNL, Berkeley, CA, United States
| | - Jeffrey V. Rosenfeld
- Monash Institute of Medical Engineering, Monash University, Clayton, VIC, Australia
- Department of Neurosurgery, Alfred Hospital, Melbourne, VIC, Australia
- Department of Surgery, Monash University, Clayton, VIC, Australia
- Department of Surgery, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Tad Hogg
- Institute for Molecular Manufacturing, Palo Alto, CA, United States
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Protein Kinase C in the Cerebellum: Its Significance and Remaining Conundrums. THE CEREBELLUM 2019; 17:23-27. [PMID: 29134360 DOI: 10.1007/s12311-017-0898-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protein kinase C (PKC), a family of serine/threonine protein kinases, mediates a myriad of patho-physiological cellular events in various tissues. The originally discovered PKC (conventional) requires the binding of diacylglycerol and Ca2+ for full activation. The conventional PKC consists of four isoforms, PKCα, PKCβI/βII, and PKCγ. PKCα and PKCβI/βII are expressed in the cells of various tissues including the brain, while PKCγ is present specifically in neurons of the brain and spinal cord. The cerebellum expresses the largest amount of PKC with all its four isoforms. Purkinje cells express PKCα and PKCγ. Previous studies have shown that PKCα is involved in the induction of long-term depression (LTD) at parallel fiber-Purkinje cell synapses. On the other hand, analysis of PKCγ-deficient mice has revealed that PKCγ plays a critical role in eliminating supernumerary climbing fiber synapses from developing Purkinje cells. Although why PKCα has no compensatory action in climbing fiber pruning in PKCγ-deficient Purkinje cells had so far remained unclear, we have recently demonstrated that PKCα is also capable of pruning supernumerary climbing fiber synapses, but the expression levels of PKCα are too low to achieve pruning in PKCγ-null Purkinje cells. Notably, although PKCγ is most abundant in Purkinje cells, its physiological role in mature Purkinje cells remained totally unknown. In addition to a concise review of the physiological and pathological roles of conventional PKCs in Purkinje cells, this report postulates a contribution of PKCα in developing Purkinje cells and a possible involvement of PKCγ in motor coordination in the mature cerebellum.
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