1
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Pennock RL, Coddington LT, Yan X, Overstreet-Wadiche L, Wadiche JI. Afferent convergence to a shared population of interneuron AMPA receptors. Nat Commun 2023; 14:3113. [PMID: 37253743 PMCID: PMC10229553 DOI: 10.1038/s41467-023-38854-2] [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: 12/19/2022] [Accepted: 05/12/2023] [Indexed: 06/01/2023] Open
Abstract
Precise alignment of pre- and postsynaptic elements optimizes the activation of glutamate receptors at excitatory synapses. Nonetheless, glutamate that diffuses out of the synaptic cleft can have actions at distant receptors, a mode of transmission called spillover. To uncover the extrasynaptic actions of glutamate, we localized AMPA receptors (AMPARs) mediating spillover transmission between climbing fibers and molecular layer interneurons in the cerebellar cortex. We found that climbing fiber spillover generates calcium transients mediated by Ca2+-permeable AMPARs at parallel fiber synapses. Spillover occludes parallel fiber synaptic currents, indicating that separate, independently regulated afferent pathways converge onto a common pool of AMPARs. Together these findings demonstrate a circuit motif wherein glutamate 'spill-in' from an unconnected afferent pathway co-opts synaptic receptors, allowing activation of postsynaptic AMPARs even when canonical glutamate release is suppressed.
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Affiliation(s)
- Reagan L Pennock
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Luke T Coddington
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
- Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA, 20147, USA
| | - Xiaohui Yan
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | | | - Jacques I Wadiche
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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2
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Yakoubi R, Rollenhagen A, von Lehe M, Shao Y, Sätzler K, Lübke JHR. Quantitative Three-Dimensional Reconstructions of Excitatory Synaptic Boutons in Layer 5 of the Adult Human Temporal Lobe Neocortex: A Fine-Scale Electron Microscopic Analysis. Cereb Cortex 2020; 29:2797-2814. [PMID: 29931200 DOI: 10.1093/cercor/bhy146] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/22/2018] [Accepted: 05/29/2018] [Indexed: 11/14/2022] Open
Abstract
Studies of synapses are available for different brain regions of several animal species including non-human primates, but comparatively little is known about their quantitative morphology in humans. Here, synaptic boutons in Layer 5 (L5) of the human temporal lobe (TL) neocortex were investigated in biopsy tissue, using fine-scale electron microscopy, and quantitative three-dimensional reconstructions. The size and organization of the presynaptic active zones (PreAZs), postsynaptic densities (PSDs), and that of the 3 distinct pools of synaptic vesicles (SVs) were particularly analyzed. L5 synaptic boutons were medium-sized (~6 μm2) with a single but relatively large PreAZ (~0.3 μm2). They contained a total of ~1500 SVs/bouton, ~20 constituting the putative readily releasable pool (RRP), ~180 the recycling pool (RP), and the remainder, the resting pool. The PreAZs, PSDs, and vesicle pools are ~3-fold larger than those of CNS synapses in other species. Astrocytic processes reached the synaptic cleft and may regulate the glutamate concentration. Profound differences exist between synapses in human TL neocortex and those described in various species, particularly in the size and geometry of PreAZs and PSDs, the large RRP/RP, and the astrocytic ensheathment suggesting high synaptic efficacy, strength, and modulation of synaptic transmission at human synapses.
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Affiliation(s)
- Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Marec von Lehe
- University Hospital/Knappschaftskrankenhaus Bochum, In der Schornau 23-25, Bochum, Germany.,Department of Neurosurgery, Ruppiner Kliniken, Medizinische Hochschule Brandenburg, Fehrbelliner Str. 38, Neuruppin, Germany
| | - Yachao Shao
- Simulation Lab Neuroscience, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,College of Computer, National University of Defense Technology, Changsha, China
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Cromore Rd., BT52 1SA, Londonderry, UK
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty/RWTH University Hospital Aachen, Pauwelsstr. 30, Aachen, Germany.,JARA Translational Brain Medicine, Germany
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3
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Yakoubi R, Rollenhagen A, von Lehe M, Miller D, Walkenfort B, Hasenberg M, Sätzler K, Lübke JH. Ultrastructural heterogeneity of layer 4 excitatory synaptic boutons in the adult human temporal lobe neocortex. eLife 2019; 8:48373. [PMID: 31746736 PMCID: PMC6919978 DOI: 10.7554/elife.48373] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 11/19/2019] [Indexed: 01/09/2023] Open
Abstract
Synapses are fundamental building blocks controlling and modulating the ‘behavior’ of brain networks. How their structural composition, most notably their quantitative morphology underlie their computational properties remains rather unclear, particularly in humans. Here, excitatory synaptic boutons (SBs) in layer 4 (L4) of the temporal lobe neocortex (TLN) were quantitatively investigated. Biopsies from epilepsy surgery were used for fine-scale and tomographic electron microscopy (EM) to generate 3D-reconstructions of SBs. Particularly, the size of active zones (AZs) and that of the three functionally defined pools of synaptic vesicles (SVs) were quantified. SBs were comparatively small (~2.50 μm2), with a single AZ (~0.13 µm2); preferentially established on spines. SBs had a total pool of ~1800 SVs with strikingly large readily releasable (~20), recycling (~80) and resting pools (~850). Thus, human L4 SBs may act as ‘amplifiers’ of signals from the sensory periphery, integrate, synchronize and modulate intra- and extracortical synaptic activity.
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Affiliation(s)
- Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany
| | - Marec von Lehe
- Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany.,Department of Neurosurgery, Brandenburg Medical School, Ruppiner Clinics, Neuruppin, Germany
| | - Dorothea Miller
- Department of Neurosurgery, Knappschaftskrankenhaus Bochum, Bochum, Germany
| | - Bernd Walkenfort
- Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
| | - Mike Hasenberg
- Medical Research Centre, IMCES Electron Microscopy Unit (EMU), University Hospital Essen, Essen, Germany
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Londonderry, United Kingdom
| | - Joachim Hr Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Faculty of Medicine, RWTH University Hospital Aachen, Aachen, Germany.,JARA Translational Brain Medicine, Jülich/Aachen, Germany
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4
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Kitahara Y, Ohta K, Hasuo H, Shuto T, Kuroiwa M, Sotogaku N, Togo A, Nakamura KI, Nishi A. Chronic Fluoxetine Induces the Enlargement of Perforant Path-Granule Cell Synapses in the Mouse Dentate Gyrus. PLoS One 2016; 11:e0147307. [PMID: 26788851 PMCID: PMC4720354 DOI: 10.1371/journal.pone.0147307] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/01/2016] [Indexed: 12/27/2022] Open
Abstract
A selective serotonin reuptake inhibitor is the most commonly prescribed antidepressant for the treatment of major depression. However, the mechanisms underlying the actions of selective serotonin reuptake inhibitors are not fully understood. In the dentate gyrus, chronic fluoxetine treatment induces increased excitability of mature granule cells (GCs) as well as neurogenesis. The major input to the dentate gyrus is the perforant path axons (boutons) from the entorhinal cortex (layer II). Through voltage-sensitive dye imaging, we found that the excitatory neurotransmission of the perforant path synapse onto the GCs in the middle molecular layer of the mouse dentate gyrus (perforant path-GC synapse) is enhanced after chronic fluoxetine treatment (15 mg/kg/day, 14 days). Therefore, we further examined whether chronic fluoxetine treatment affects the morphology of the perforant path-GC synapse, using FIB/SEM (focused ion beam/scanning electron microscopy). A three-dimensional reconstruction of dendritic spines revealed the appearance of extremely large-sized spines after chronic fluoxetine treatment. The large-sized spines had a postsynaptic density with a large volume. However, chronic fluoxetine treatment did not affect spine density. The presynaptic boutons that were in contact with the large-sized spines were large in volume, and the volumes of the mitochondria and synaptic vesicles inside the boutons were correlated with the size of the boutons. Thus, the large-sized perforant path-GC synapse induced by chronic fluoxetine treatment contains synaptic components that correlate with the synapse size and that may be involved in enhanced glutamatergic neurotransmission.
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Affiliation(s)
- Yosuke Kitahara
- Department of Pharmacology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Keisuke Ohta
- Department of Anatomy, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Hiroshi Hasuo
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Takahide Shuto
- Department of Pharmacology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Mahomi Kuroiwa
- Department of Pharmacology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Naoki Sotogaku
- Department of Pharmacology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Akinobu Togo
- Department of Anatomy, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Kei-ichiro Nakamura
- Department of Anatomy, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
| | - Akinori Nishi
- Department of Pharmacology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830–0011, Japan
- * E-mail:
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5
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Dufour A, Rollenhagen A, Sätzler K, Lübke JHR. Development of Synaptic Boutons in Layer 4 of the Barrel Field of the Rat Somatosensory Cortex: A Quantitative Analysis. Cereb Cortex 2015; 26:838-854. [PMID: 26574502 PMCID: PMC4712807 DOI: 10.1093/cercor/bhv270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Understanding the structural and functional mechanisms underlying the development of individual brain microcircuits is critical for elucidating their computational properties. As synapses are the key structures defining a given microcircuit, it is imperative to investigate their development and precise structural features. Here, synapses in cortical layer 4 were analyzed throughout the first postnatal month using high-end electron microscopy to generate realistic quantitative 3D models. Besides their overall geometry, the size of active zones and the pools of synaptic vesicles were analyzed. At postnatal day 2 only a few shaft synapses were found, but spine synapses steadily increased with ongoing corticogenesis. From postnatal day 2 to 30 synaptic boutons significantly decreased in size whereas that of active zones remained nearly unchanged despite a reshaping. During the first 2 weeks of postnatal development, a rearrangement of synaptic vesicles from a loose distribution toward a densely packed organization close to the presynaptic density was observed, accompanied by the formation of, first a putative readily releasable pool and later a recycling and reserve pool. The quantitative 3D reconstructions of synapses will enable the comparison of structural and functional aspects of signal transduction thus leading to a better understanding of networks in the developing neocortex.
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Affiliation(s)
- Amandine Dufour
- Institute of Neuroscience and Medicine INM-2, Research Centre Jülich GmbH, Jülich 52425, Germany.,Institute of Anatomy II, Medical Faculty, Heinrich-Heine University Düsseldorf, Düsseldorf 40225, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-2, Research Centre Jülich GmbH, Jülich 52425, Germany
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Londonderry BT52 1SA, UK
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-2, Research Centre Jülich GmbH, Jülich 52425, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH/University Hospital Aachen, Aachen 52074, Germany.,JARA Translational Brain Medicine, Aachen 52074, Germany
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6
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Medvedev N, Popov V, Henneberger C, Kraev I, Rusakov DA, Stewart MG. Glia selectively approach synapses on thin dendritic spines. Philos Trans R Soc Lond B Biol Sci 2015; 369:20140047. [PMID: 25225105 PMCID: PMC4173297 DOI: 10.1098/rstb.2014.0047] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This paper examines the relationship between the morphological modality of 189 dendritic spines and the surrounding astroglia using full three-dimensional reconstructions of neuropil fragments. An integrative measure of three-dimensional glial coverage confirms that thin spine postsynaptic densities are more tightly surrounded by glia. This distinction suggests that diffusion-dependent synapse-glia communication near 'learning' synapses (associated with thin spines) could be stronger than that near 'memory' synapses (associated with larger spines).
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Affiliation(s)
- Nikolai Medvedev
- Department of Life and Health Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Victor Popov
- Department of Life and Health Sciences, The Open University, Milton Keynes MK7 6AA, UK Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino 142290, Russia
| | - Christian Henneberger
- Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Igor Kraev
- Department of Life and Health Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Dmitri A Rusakov
- Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Michael G Stewart
- Department of Life and Health Sciences, The Open University, Milton Keynes MK7 6AA, UK
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7
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Saturated Reconstruction of a Volume of Neocortex. Cell 2015; 162:648-61. [PMID: 26232230 DOI: 10.1016/j.cell.2015.06.054] [Citation(s) in RCA: 587] [Impact Index Per Article: 65.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 03/10/2015] [Accepted: 06/01/2015] [Indexed: 11/20/2022]
Abstract
We describe automated technologies to probe the structure of neural tissue at nanometer resolution and use them to generate a saturated reconstruction of a sub-volume of mouse neocortex in which all cellular objects (axons, dendrites, and glia) and many sub-cellular components (synapses, synaptic vesicles, spines, spine apparati, postsynaptic densities, and mitochondria) are rendered and itemized in a database. We explore these data to study physical properties of brain tissue. For example, by tracing the trajectories of all excitatory axons and noting their juxtapositions, both synaptic and non-synaptic, with every dendritic spine we refute the idea that physical proximity is sufficient to predict synaptic connectivity (the so-called Peters' rule). This online minable database provides general access to the intrinsic complexity of the neocortex and enables further data-driven inquiries.
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8
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Bosch C, Martínez A, Masachs N, Teixeira CM, Fernaud I, Ulloa F, Pérez-Martínez E, Lois C, Comella JX, DeFelipe J, Merchán-Pérez A, Soriano E. FIB/SEM technology and high-throughput 3D reconstruction of dendritic spines and synapses in GFP-labeled adult-generated neurons. Front Neuroanat 2015; 9:60. [PMID: 26052271 PMCID: PMC4440362 DOI: 10.3389/fnana.2015.00060] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 04/29/2015] [Indexed: 12/24/2022] Open
Abstract
The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3–4 and 8–9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner.
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Affiliation(s)
- Carles Bosch
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Institut de Recerca de l'Hospital Universitari de la Vall d'Hebron (VHIR) Barcelona, Spain
| | - Albert Martínez
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain
| | - Nuria Masachs
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain
| | - Cátia M Teixeira
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain
| | - Isabel Fernaud
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Campus de Montegancedo Madrid, Spain ; Instituto Cajal (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Fausto Ulloa
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain
| | - Esther Pérez-Martínez
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain
| | - Carlos Lois
- Department of Neurobiology, University of Massachusetts Medical School Worcester, MA, USA
| | - Joan X Comella
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Institut de Recerca de l'Hospital Universitari de la Vall d'Hebron (VHIR) Barcelona, Spain ; Institut de Neurociències, Departament de Bioquímica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona Bellaterra, Spain
| | - Javier DeFelipe
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Campus de Montegancedo Madrid, Spain ; Instituto Cajal (Consejo Superior de Investigaciones Científicas) Madrid, Spain
| | - Angel Merchán-Pérez
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Campus de Montegancedo Madrid, Spain ; Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Escuela Técnica Superior de Ingenieros Informáticos, Universidad Politécnica de Madrid Madrid, Spain
| | - Eduardo Soriano
- Developmental Neurobiology and Regeneration Unit, Department of Cell Biology and Parc Cientific de Barcelona, University of Barcelona Barcelona, Spain ; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Insituto de Salul Carlos III Madrid, Spain ; Institut de Recerca de l'Hospital Universitari de la Vall d'Hebron (VHIR) Barcelona, Spain ; Institució Catalana de Recerca i Estudis Avançats Academia Barcelona, Spain
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9
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Brusco J, Merlo S, Ikeda ÉT, Petralia RS, Kachar B, Rasia-Filho AA, Moreira JE. Inhibitory and multisynaptic spines, and hemispherical synaptic specialization in the posterodorsal medial amygdala of male and female rats. J Comp Neurol 2015; 522:2075-88. [PMID: 24318545 DOI: 10.1002/cne.23518] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/26/2013] [Accepted: 12/03/2013] [Indexed: 12/23/2022]
Abstract
The density of dendritic spines is sexually dimorphic and variable throughout the female estrous cycle in the rat posterodorsal medial amygdala (MePD), a relevant area for the modulation of reproductive behavior in rats. The local synaptic activity differs between hemispheres in prepubertal animals. Here we used serial section transmission electron microscopy to produce 3D reconstructions of dendritic shafts and spines to characterize synaptic contacts on MePD neurons of both hemispheres in adult males and in females along the estrous cycle. Pleomorphic spines and nonsynaptic filopodia occur in the MePD. On average, 8.6% of dendritic spines received inputs from symmetric gamma-aminobutyric acid (GABA)-immunoreactive terminals, whereas 3.6% received two synaptic contacts on the spine head, neck, or base. Presynaptic terminals in female right MePD had a higher density of synaptic vesicles and docked vesicles than the left MePD, suggesting a higher rate of synaptic vesicle release in the right MePD of female rats. In contrast, males did not show laterality in any of those parameters. The proportion of putative inhibitory synapses on dendritic shafts in the right MePD of females in proestrus was higher than in the left MePD, and higher than in the right MePD in males, or in females in diestrus or estrus. This work shows synaptic laterality depending on sex and estrous cycle phase in mature MePD neurons. Most likely, sexual hormone effects are lateralized in this brain region, leading to higher synaptic activity in the right than in the left hemisphere of females, mediating timely neuroendocrine and social/reproductive behavior.
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Affiliation(s)
- Janaina Brusco
- Department of Neuroscience and Behavior, University of São Paulo, School of Medicine at Ribeirão Preto, Ribeirão Preto, SP, 14049-900, Brazil; National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, 20892, USA
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10
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Zhang Y, Meredith GE, Mendoza-Elias N, Rademacher DJ, Tseng KY, Steece-Collier K. Aberrant restoration of spines and their synapses in L-DOPA-induced dyskinesia: involvement of corticostriatal but not thalamostriatal synapses. J Neurosci 2013; 33:11655-67. [PMID: 23843533 PMCID: PMC3724545 DOI: 10.1523/jneurosci.0288-13.2013] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 05/07/2013] [Accepted: 06/05/2013] [Indexed: 11/21/2022] Open
Abstract
We examined the structural plasticity of excitatory synapses from corticostriatal and thalamostriatal pathways and their postsynaptic targets in adult Sprague-Dawley rats to understand how these striatal circuits change in l-DOPA-induced dyskinesias (LIDs). We present here detailed electron and light microscopic analyses that provide new insight into the nature of the structural and synaptic remodeling of medium spiny neurons in response to LIDs. Numerous studies have implicated enhanced glutamate signaling and persistent long-term potentiation as central to the behavioral sensitization phenomenon of LIDs. Moreover, experience-dependent alterations in behavior are thought to involve structural modifications, specifically alterations in patterns of synaptic connectivity. Thus, we hypothesized that in the striatum of rats with LIDs, one of two major glutamatergic pathways would form new or altered contacts, especially onto the spines of medium spiny neuron (MSNs). Our data provide compelling evidence for a dramatic rewiring of the striatum of dyskinetic rats and that this rewiring involves corticostriatal but not thalamostriatal contacts onto MSNs. There is a dramatic increase in corticostriatal contacts onto spines and dendrites that appear to be directly linked to dyskinetic behaviors, since they were not seen in the striatum of animals that did not develop dyskinesia. There is also an aberrant increase in spines receiving more than one excitatory contact(i.e., multisynaptic spines) in the dyskinetic animals compared with the 6-hydroxydopamine-treated and control rats. Such alterations could substantially impair the ability of striatal neurons to gate cortically driven signals and contribute to the loss of bidirectional synaptic plasticity.
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Affiliation(s)
- Yiyue Zhang
- Department of Pharmaceutical Sciences, College of Pharmacy, and
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, and
| | | | - Nasya Mendoza-Elias
- Department of Pharmaceutical Sciences, College of Pharmacy, and
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, and
| | - David J. Rademacher
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, Michigan 49503
| | - Kuei Y. Tseng
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Illinois 60064, and
| | - Kathy Steece-Collier
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, Michigan 49503
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11
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Dall'Oglio A, Xavier LL, Hilbig A, Ferme D, Moreira JE, Achaval M, Rasia-Filho AA. Cellular components of the human medial amygdaloid nucleus. J Comp Neurol 2013; 521:589-611. [PMID: 22806548 DOI: 10.1002/cne.23192] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 04/22/2012] [Accepted: 07/10/2012] [Indexed: 12/24/2022]
Abstract
The medial nucleus (Me) is a superficial component of the amygdaloid complex. Here we assessed the density and morphology of the neurons and glial cells, the glial fibrillary acidic protein (GFAP) immunoreactivity, and the ultrastructure of the synaptic sites in the human Me. The optical fractionator method was applied. The Me presented an estimated mean neuronal density of 1.53 × 10⁵ neurons/mm³ (greater in the left hemisphere), more glia (72% of all cells) than neurons, and a nonneuronal:neuronal ratio of 2.7. Golgi-impregnated neurons had round or ovoid, fusiform, angular, and polygonal cell bodies (10-30 μm in diameter). The length of the dendrites varied, and pleomorphic spines were found in sparsely spiny or densely spiny cells (1.5-5.2 spines/dendritic μm). The axons in the Me neuropil were fine or coarsely beaded, and fibers showed simple or notably complex collateral terminations. The protoplasmic astrocytes were either isolated or formed small clusters and showed GFAP-immunoreactive cell bodies and multiple branches. Furthermore, we identified both asymmetrical (with various small, clear, round, electron-lucent vesicles and, occasionally, large, dense-core vesicles) and symmetrical (with small, flattened vesicles) axodendritic contacts, also including multisynaptic spines. The astrocytes surround and may compose tripartite or tetrapartite synapses, the latter including the extracellular matrix between the pre- and the postsynaptic elements. Interestingly, the terminal axons exhibited a glomerular-like structure with various asymmetrical contacts. These new morphological data on the cellular population and synaptic complexity of the human Me can contribute to our knowledge of its role in health and pathological conditions.
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Affiliation(s)
- Aline Dall'Oglio
- Neuroscience Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre 90170-050-RS, Brazil
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Clemo HR, Meredith MA. Dendritic spine density in multisensory versus primary sensory cortex. Synapse 2012; 66:714-24. [PMID: 22488884 DOI: 10.1002/syn.21560] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 03/22/2012] [Accepted: 03/23/2012] [Indexed: 11/09/2022]
Abstract
In sensory areas, neuronal dendritic spines receive sensory-specific inputs whose net activity drives neuronal spiking responses to effective external stimuli. Previous studies indicate that neurons in primary sensory cortical areas, which largely receive inputs from a single sensory modality, exhibit an average of 0.5-1.4 dendritic spines/μm, depending on species. In higher-order, associational cortices, inputs converge from multiple sensory sources onto individual, multisensory neurons. This raises the question: when inputs from two different modalities converge onto individual neurons, how are the dendritic spines apportioned to subserve the generation of robust spiking responses to each modality? As inputs arrive from two different sensory sources, it might be expected that neurons in multisensory areas exhibit approximately double the spine density of neurons in areas that receive just one sensory input. The present study examined this possibility in Golgi-stained neurons from ferret primary auditory (A1) and somatosensory (S1) cortices, as well as from regions in which inputs from two different sensory modalities converge: the lateral rostral suprasylvian sulcus (LRSS) and the rostral posterior parietal (PPr) areas. Dendritic spine density (spines/μm) was measured for pyramidal neurons in layers 2-3 and layers 5-6 for each cortical area from three animals using light microscopy. Primary sensory regions A1 and S1 showed remarkably similar average spine densities (A1 = 1.27 spines/μm ± 0.3 s.d.; S1 = 1.14 spines/μm ± 0.3), but average spine densities from the multisensory areas were lower (LRSS = 0.98 ± 0.3; PPr = 1.04 ± 0.3). Thus, for a given cortical area, dendritic spine density appears to be determined by factors other than the levels of sensory modality convergence.
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Affiliation(s)
- H Ruth Clemo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, School of Medicine, Richmond, Virginia, USA.
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Tapia JC, Kasthuri N, Hayworth KJ, Schalek R, Lichtman JW, Smith SJ, Buchanan J. High-contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy. Nat Protoc 2012; 7:193-206. [PMID: 22240582 DOI: 10.1038/nprot.2011.439] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Conventional heavy metal poststaining methods on thin sections lend contrast but often cause contamination. To avoid this problem, we tested several en bloc staining techniques to contrast tissue in serial sections mounted on solid substrates for examination by field emission scanning electron microscopy (FESEM). Because FESEM section imaging requires that specimens have higher contrast and greater electrical conductivity than transmission electron microscopy (TEM) samples, our technique uses osmium impregnation (OTO) to make the samples conductive while heavily staining membranes for segmentation studies. Combining this step with other classic heavy metal en bloc stains, including uranyl acetate (UA), lead aspartate, copper sulfate and lead citrate, produced clean, highly contrasted TEM and scanning electron microscopy (SEM) samples of insect, fish and mammalian nervous systems. This protocol takes 7-15 d to prepare resin-embedded tissue, cut sections and produce serial section images.
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Affiliation(s)
- Juan Carlos Tapia
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
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Homeostatic responses by surviving cortical pyramidal cells in neurodegenerative tauopathy. Acta Neuropathol 2011; 122:551-64. [PMID: 21968531 DOI: 10.1007/s00401-011-0877-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/16/2011] [Accepted: 09/16/2011] [Indexed: 10/17/2022]
Abstract
Cortical neuron death is prevalent by 9 months in rTg(tau(P301L))4510 tau mutant mice (TG) and surviving pyramidal cells exhibit dendritic regression and spine loss. We used whole-cell patch-clamp recordings to investigate the impact of these marked structural changes on spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) of layer 3 pyramidal cells in frontal cortical slices from behaviorally characterized TG and non-transgenic (NT) mice at this age. Frontal lobe function of TG mice was intact following a short delay interval but impaired following a long delay interval in an object recognition test, and cortical atrophy and cell loss were pronounced. Surviving TG cells had significantly reduced dendritic diameters, total spine density, and mushroom spines, yet sEPSCs were increased and sIPSCs were unchanged in frequency. Thus, despite significant regressive structural changes, synaptic responses were not reduced in TG cells, indicating that homeostatic compensatory mechanisms occur during progressive tauopathy. Consistent with this idea, surviving TG cells were more intrinsically excitable than NT cells, and exhibited sprouting of filopodia and axonal boutons. Moreover, the neuropil in TG mice showed an increased density of asymmetric synapses, although their mean size was reduced. Taken together, these data indicate that during progressive tauopathy, cortical pyramidal cells compensate for loss of afferent input by increased excitability and establishment of new synapses. These compensatory homeostatic mechanisms may play an important role in slowing the progression of neuronal network dysfunction during neurodegenerative tauopathies.
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15
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Popov VI, Kleschevnikov AM, Klimenko OA, Stewart MG, Belichenko PV. Three-dimensional synaptic ultrastructure in the dentate gyrus and hippocampal area CA3 in the Ts65Dn mouse model of Down syndrome. J Comp Neurol 2011; 519:1338-54. [PMID: 21452200 DOI: 10.1002/cne.22573] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Down syndrome (DS) results from trisomy of human chromosome 21. Ts65Dn mice are an established model for DS and show several phenotypes similar to those in people with DS. However, there is little data on the structural plasticity of synapses in the trisynaptic pathway in the hippocampus. Here we investigate 3D ultrastructure of synapses in the hippocampus of age-matched control (2N) and Ts65Dn male mice. Serial ultrathin sections and 3D reconstructions characterize synapses in the middle molecular layer (MML) of dentate gyrus and in thorny excrescences (TEs) in proximal portions of apical dendrites of CA3 pyramidal neurons. 3D analysis of synapses shows phenotypes that distinguish Ts65Dn from 2N mice. For the MML, synapse density was reduced by 15% in Ts65Dn vs. 2N mice (P < 0.05). Comparative 3D analyses demonstrate a significant decrease in the number of thorns per TE in CA3 in Ts65Dn vs. 2N mice (by ≈45%, P = 0.01). Individual thorn volume was 3 times smaller in Ts65Dn vs. 2N mice (P = 0.02). A significant decrease in the number of thorn projections per TE in Ts65Dn vs. 2N mice was accompanied by a decrease of filopodium-like protrusions on the surface of TEs (P = 0.02). However, the volume of postsynaptic densities in CA3 Ts65Dn and 2N mice was unchanged (P = 0.78). Our findings suggest that the high degree of plasticity of CA3 thorns may be connected with their filopodial origin. Alterations of 3D synaptic structure in Ts65Dn mice may further contribute to the diminished plasticity in DS.
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Affiliation(s)
- Victor I Popov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia.
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Descriptive findings on the morphology of dendritic spines in the rat medial amygdala. Neurosci Lett 2010; 483:152-6. [DOI: 10.1016/j.neulet.2010.07.083] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Revised: 07/23/2010] [Accepted: 07/28/2010] [Indexed: 12/16/2022]
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Popov VI, Kraev IV, Banks D, Davies HA, Morenkov ED, Stewart MG, Fesenko EE. Three-dimensional ultrastructural and immunohistochemical study of immature neurons in the subgranular zone of the rat dentate gyrus. Biophysics (Nagoya-shi) 2009. [DOI: 10.1134/s0006350909040174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Kraev IV, Godukhin OV, Patrushev IV, Davies HA, Popov VI, Stewart MG. Partial kindling induces neurogenesis, activates astrocytes and alters synaptic morphology in the dentate gyrus of freely moving adult rats. Neuroscience 2009; 162:254-67. [PMID: 19447163 DOI: 10.1016/j.neuroscience.2009.05.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 04/30/2009] [Accepted: 05/10/2009] [Indexed: 12/01/2022]
Abstract
A partial kindling procedure was used to investigate the correlation between focal seizure development and changes in dendritic spine morphology, ongoing neurogenesis and reactive astrogliosis in the adult rat dentate gyrus (DG). The processes of neurogenesis and astrogliosis were investigated using markers for doublecortin (DCX), 5-bromo-2-deoxyuridine (BrdU) and glial fibrillary acidic protein (GFAP). Our data demonstrate that mild focal seizures induce a complex series of cellular events in the DG one day after cessation of partial rapid kindling stimulation consisting (in comparison to control animals that were electrode implanted but unkindled), firstly, of an increase in the number of postmitotic BrdU labeled cells, and secondly, an increase in the number of DCX labeled cells, mainly in subgranular zone. Ultrastructural changes were examined using qualitative electron microscope analysis and 3-D reconstructions of both dendritic spines and postsynaptic densities. Typical features of kindling in comparison to control tissue included translocation of mitochondria to the base of the dendritic spine stalks; a migration of multivesicular bodies into mushroom dendritic spines, and most notably formation of "giant" spinules originating from the head of the spines of DG neurons. These morphological alterations arise at seizure stages 2-3 (focal seizures) in the absence of signs of the severe generalized seizures that are generally recognized as potentially harmful for neuronal cells. We suggest that an increase in ongoing neurogenesis, reactive astrogliosis and dendritic spine reorganization in the DG is the crucial step in the chain of events leading to the progressive development of seizure susceptibility in hippocampal circuits.
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Affiliation(s)
- I V Kraev
- Department of Life Sciences, Faculty of Science, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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