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Yan J, Ton H, Yan J, Dong Y, Xie Z, Jiang H. Anesthetic Sevoflurane Induces Enlargement of Dendritic Spine Heads in Mouse Neurons via Tau-Dependent Mechanisms. Anesth Analg 2024:00000539-990000000-00796. [PMID: 38507523 DOI: 10.1213/ane.0000000000006941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
BACKGROUND Sevoflurane induces neuronal dysfunction and cognitive impairment. However, the underlying mechanism remains largely to be determined. Tau, cyclophilin D, and dendritic spine contribute to cognitive function. But whether changes in dendritic spines are involved in the effects of sevoflurane and the potential association with tau and cyclophilin D is not clear. METHODS We harvested hippocampal neurons from wild-type mice, tau knockout mice, and cyclophilin D knockout mice. We treated these neurons with sevoflurane at day in vitro 7 and measured the diameter of dendritic spine head and the number of dendritic spines. Moreover, we determined the effects of sevoflurane on the expression of excitatory amino acid transporter 3 (EAAT3), extracellular glutamate levels, and miniature excitatory postsynaptic currents (mEPSCs). Finally, we used lithium, cyclosporine A, and overexpression of EAAT3 in the interaction studies. RESULTS Sevoflurane-induced tau phosphgorylation increased the diameter of dendritic spine head and decreased the number of dendritic spines in neurons harvested from wild-type and cyclophilin D knockout mice, but not tau knockout mice. Sevoflurane decreased the expression of EAAT3, increased extracellular glutamate levels, and decreased the frequency of mEPSCs in the neurons. Overexpression of EAAT3 mitigated the effects of sevoflurane on dendritic spines. Lithium, but not cyclosporine A, attenuated the effects of sevoflurane on dendritic spines. Lithium also inhibited the effects of sevoflurane on EAAT3 expression and mEPSCs. CONCLUSIONS These data suggest that sevoflurane induces a tau phosphorylation-dependent demtrimental effect on dendritic spine via decreasing EAAT3 expression and increasing extracellular glutamate levels, leading to neuronal dysfunction.
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Affiliation(s)
- Jia Yan
- From the Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Hoai Ton
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Jing Yan
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
- Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuanlin Dong
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Zhongcong Xie
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Hong Jiang
- From the Department of Anesthesiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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2
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Samavat M, Bartol TM, Bromer C, Hubbard DD, Hanka DC, Kuwajima M, Mendenhall JM, Parker PH, Bowden JB, Abraham WC, Sejnowski TJ, Harris KM. Long-Term Potentiation Produces a Sustained Expansion of Synaptic Information Storage Capacity in Adult Rat Hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.574766. [PMID: 38260636 PMCID: PMC10802612 DOI: 10.1101/2024.01.12.574766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Long-term potentiation (LTP) has become a standard model for investigating synaptic mechanisms of learning and memory. Increasingly, it is of interest to understand how LTP affects the synaptic information storage capacity of the targeted population of synapses. Here, structural synaptic plasticity during LTP was explored using three-dimensional reconstruction from serial section electron microscopy. Storage capacity was assessed by applying a new analytical approach, Shannon information theory, to delineate the number of functionally distinguishable synaptic strengths. LTP was induced by delta-burst stimulation of perforant pathway inputs to the middle molecular layer of hippocampal dentate granule cells in adult rats. Spine head volumes were measured as predictors of synaptic strength and compared between LTP and control hemispheres at 30 min and 2 hr after the induction of LTP. Synapses from the same axon onto the same dendrite were used to determine the precision of synaptic plasticity based on the similarity of their physical dimensions. Shannon entropy was measured by exploiting the frequency of spine heads in functionally distinguishable sizes to assess the degree to which LTP altered the number of bits of information storage. Outcomes from these analyses reveal that LTP expanded storage capacity; the distribution of spine head volumes was increased from 2 bits in controls to 3 bits at 30 min and 2.7 bits at 2 hr after the induction of LTP. Furthermore, the distribution of spine head volumes was more uniform across the increased number of functionally distinguishable sizes following LTP, thus achieving more efficient use of coding space across the population of synapses.
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Affiliation(s)
- Mohammad Samavat
- Department of Electrical and Computer Engineering, Jacobs School of Engineering, UC San Diego
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Thomas M Bartol
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Cailey Bromer
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
| | - Dusten D Hubbard
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Dakota C Hanka
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Masaaki Kuwajima
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - John M Mendenhall
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Patrick H Parker
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
| | - Jared B Bowden
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712
| | - Wickliffe C Abraham
- Department of Psychology and Brain Health Research Centre, University of Otago, Dunedin, 9016, New Zealand
| | - Terrence J Sejnowski
- Computational Neurobiology Laboratory, The Salk Institute for Biological Sciences, La Jolla, CA 92037
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Kristen M Harris
- Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
- Department of Neuroscience, The University of Texas at Austin, Austin, TX 78712
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3
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Pérez-Garza J, Parrish-Mulliken E, Deane Z, Ostroff LE. Rehydration of Freeze Substituted Brain Tissue for Pre-embedding Immunoelectron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1694-1704. [PMID: 37584524 PMCID: PMC10541149 DOI: 10.1093/micmic/ozad077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/27/2023] [Accepted: 07/16/2023] [Indexed: 08/17/2023]
Abstract
Electron microscopy (EM) volume reconstruction is a powerful tool for investigating the fundamental structure of brain circuits, but the full potential of this technique is limited by the difficulty of integrating molecular information. High quality ultrastructural preservation is necessary for EM reconstruction, and intact, highly contrasted cell membranes are essential for following small neuronal processes through serial sections. Unfortunately, the antibody labeling methods used to identify most endogenous molecules result in compromised morphology, especially of membranes. Cryofixation can produce superior morphological preservation and has the additional advantage of allowing indefinite storage of valuable samples. We have developed a method based on cryofixation that allows sensitive immunolabeling of endogenous molecules, preserves excellent ultrastructure, and is compatible with high-contrast staining for serial EM reconstruction.
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Affiliation(s)
- Janeth Pérez-Garza
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Emily Parrish-Mulliken
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Zachary Deane
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
| | - Linnaea E Ostroff
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Rd. Unit 3156, Storrs, CT 06269-3156, USA
- Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Rd. Unit 1272, Storrs, CT 06269-1272, USA
- Institute of Materials Science, University of Connecticut, 25 King Hill Rd. Unit 3136, Storrs, CT 06269-3136, USA
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4
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Shishkova EA, Kraev IV, Rogachevsky VV. Evaluation of Oolong Tea Extract Staining of Brain Tissue with Special Reference to Smooth Endoplasmic Reticulum. Biophysics (Nagoya-shi) 2022. [DOI: 10.1134/s0006350922050177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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5
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Heuser JE. The Structural Basis of Long-Term Potentiation in Hippocampal Synapses, Revealed by Electron Microscopy Imaging of Lanthanum-Induced Synaptic Vesicle Recycling. Front Cell Neurosci 2022; 16:920360. [PMID: 35978856 PMCID: PMC9376242 DOI: 10.3389/fncel.2022.920360] [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: 04/14/2022] [Accepted: 05/05/2022] [Indexed: 11/29/2022] Open
Abstract
Hippocampal neurons in dissociated cell cultures were exposed to the trivalent cation lanthanum for short periods (15–30 min) and prepared for electron microscopy (EM), to evaluate the stimulatory effects of this cation on synaptic ultrastructure. Not only were characteristic ultrastructural changes of exaggerated synaptic vesicle turnover seen within the presynapses of these cultures—including synaptic vesicle depletion and proliferation of vesicle-recycling structures—but the overall architecture of a large proportion of the synapses in the cultures was dramatically altered, due to large postsynaptic “bulges” or herniations into the presynapses. Moreover, in most cases, these postsynaptic herniations or protrusions produced by lanthanum were seen by EM to distort or break or “perforate” the so-called postsynaptic densities (PSDs) that harbor receptors and recognition molecules essential for synaptic function. These dramatic EM observations lead us to postulate that such PSD breakages or “perforations” could very possibly create essential substrates or “tags” for synaptic growth, simply by creating fragmented free edges around the PSDs, into which new receptors and recognition molecules could be recruited more easily, and thus, they could represent the physical substrate for the important synaptic growth process known as “long-term potentiation” (LTP). All of this was created simply in hippocampal dissociated cell cultures, and simply by pushing synaptic vesicle recycling way beyond its normal limits with the trivalent cation lanthanum, but we argued in this report that such fundamental changes in synaptic architecture—given that they can occur at all—could also occur at the extremes of normal neuronal activity, which are presumed to lead to learning and memory.
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6
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Rusakov DA, Giese KP, Sandi C, Dommett E, Overton PG. Remembering Mike Stewart. Neuropharmacology 2022; 207:108962. [PMID: 35051447 DOI: 10.1016/j.neuropharm.2022.108962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Karl Peter Giese
- Institute of Psychiatry, Physiology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Carmen Sandi
- Swiss Federal Institute of Technology in Lausanne (EPFL), Rte Cantonale, 1015, Lausanne, Switzerland
| | - Eleanore Dommett
- Institute of Psychiatry, Physiology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Paul G Overton
- Department of Psychology, University of Sheffield, Vicar Lane, Sheffield, S1 2LT, UK
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7
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Rusakov DA. Obituary for Professor Michael G. Stewart: Life in Neurosciences. Brain Res Bull 2022; 180:147-149. [DOI: 10.1016/j.brainresbull.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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8
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Śliwińska MA, Cały A, Borczyk M, Ziółkowska M, Skonieczna E, Chilimoniuk M, Bernaś T, Giese KP, Radwanska K. Long-term Memory Upscales Volume of Postsynaptic Densities in the Process that Requires Autophosphorylation of αCaMKII. Cereb Cortex 2021; 30:2573-2585. [PMID: 31800021 DOI: 10.1093/cercor/bhz261] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It is generally accepted that formation and storage of memory relies on alterations of the structure and function of brain circuits. However, the structural data, which show learning-induced and long-lasting remodeling of synapses, are still very sparse. Here, we reconstruct 1927 dendritic spines and their postsynaptic densities (PSDs), representing a postsynaptic part of the glutamatergic synapse, in the hippocampal area CA1 of the mice that underwent spatial training. We observe that in young adult (5 months), mice volume of PSDs, but not the volume of the spines, is increased 26 h after the training. The training-induced growth of PSDs is specific for the dendritic spines that lack smooth endoplasmic reticulum and spine apparatuses, and requires autophosphorylation of αCaMKII. Interestingly, aging alters training-induced ultrastructural remodeling of dendritic spines. In old mice, both the median volumes of dendritic spines and PSDs shift after training toward bigger values. Overall, our data support the hypothesis that formation of memory leaves long-lasting footprint on the ultrastructure of brain circuits; however, the form of circuit remodeling changes with age.
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Affiliation(s)
- Małgorzata Alicja Śliwińska
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland.,Laboratory of Imaging Tissue Structure and Function, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Anna Cały
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Malgorzata Borczyk
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Magdalena Ziółkowska
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Edyta Skonieczna
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Magdalena Chilimoniuk
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
| | - Tytus Bernaś
- Laboratory of Imaging Tissue Structure and Function, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland.,Department of Anatomy and Neurology, VCU School of Medicine, Richmond, VA 23298, USA
| | - K Peter Giese
- Department of Basic and Clinical Neuroscience, King's College London, 125 Coldharbour Lane, London SE5 9NU, UK
| | - Kasia Radwanska
- Laboratory of Molecular Basis of Behavior, The Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw 02-093, Poland
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9
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Rusakov DA, Stewart MG. Synaptic environment and extrasynaptic glutamate signals: The quest continues. Neuropharmacology 2021; 195:108688. [PMID: 34174263 DOI: 10.1016/j.neuropharm.2021.108688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/11/2022]
Abstract
Behaviour of a mammal relies on the brain's excitatory circuits equipped with glutamatergic synapses. In most cases, glutamate escaping from the synaptic cleft is rapidly buffered and taken up by high-affinity transporters expressed by nearby perisynaptic astroglial processes (PAPs). The spatial relationship between glutamatergic synapses and PAPs thus plays a crucial role in understanding glutamate signalling actions, yet its intricate features can only be fully appreciated using methods that operate beyond the diffraction limit of light. Here, we examine principal aspects pertaining to the receptor actions of glutamate, inside and outside the synaptic cleft in the brain, where the organisation of synaptic micro-physiology and micro-environment play a critical part. In what conditions and how far glutamate can escape the synaptic cleft activating its target receptors outside the immediate synapse has long been the subject of debate. Evidence is also emerging that neuronal activity- and astroglia-dependent glutamate spillover actions could be important across the spectrum of cognitive functions This article is part of the special issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Michael G Stewart
- Dept of Life Sciences, The Open University, Milton Keynes, MK7 6AA, UK.
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10
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The importance of ultrastructural analysis of memory. Brain Res Bull 2021; 173:28-36. [PMID: 33984429 DOI: 10.1016/j.brainresbull.2021.04.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 11/22/2022]
Abstract
Plasticity of glutamatergic synapses in the hippocampus is believed to underlie learning and memory processes. Surprisingly, very few studies report long-lasting structural changes of synapses induced by behavioral training. It remains, therefore, unclear which synaptic changes in the hippocampus contribute to memory storage. Here, we systematically compare how long-term potentiation of synaptic transmission (LTP) (a primary form of synaptic plasticity and cellular model of memory) and behavioral training affect hippocampal glutamatergic synapses at the ultrastructural level enabled by electron microscopy. The review of the literature indicates that while LTP induces growth of dendritic spines and post-synaptic densities (PSD), that represent postsynaptic part of a glutamatergic synapse, after behavioral training there is transient (< 6 h) synaptogenesis and long-lasting (> 24 h) increase in PSD volume (without a significant change of dendritic spine volume), indicating that training-induced PSD growth may reflect long-term enhancement of synaptic functions. Additionally, formation of multi-innervated spines (MIS), is associated with long-term memory in aged mice and LTP-deficient mutant mice. Since volume of PSD, as well as atypical synapses, can be reliably observed only with electron microscopy, we argue that the ultrastructural level of analysis is required to reveal synaptic changes that are associated with long-term storage of information in the brain.
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11
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Bączyńska E, Pels KK, Basu S, Włodarczyk J, Ruszczycki B. Quantification of Dendritic Spines Remodeling under Physiological Stimuli and in Pathological Conditions. Int J Mol Sci 2021; 22:4053. [PMID: 33919977 PMCID: PMC8070910 DOI: 10.3390/ijms22084053] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 12/14/2022] Open
Abstract
Numerous brain diseases are associated with abnormalities in morphology and density of dendritic spines, small membranous protrusions whose structural geometry correlates with the strength of synaptic connections. Thus, the quantitative analysis of dendritic spines remodeling in microscopic images is one of the key elements towards understanding mechanisms of structural neuronal plasticity and bases of brain pathology. In the following article, we review experimental approaches designed to assess quantitative features of dendritic spines under physiological stimuli and in pathological conditions. We compare various methodological pipelines of biological models, sample preparation, data analysis, image acquisition, sample size, and statistical analysis. The methodology and results of relevant experiments are systematically summarized in a tabular form. In particular, we focus on quantitative data regarding the number of animals, cells, dendritic spines, types of studied parameters, size of observed changes, and their statistical significance.
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Affiliation(s)
- Ewa Bączyńska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Katarzyna Karolina Pels
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Subhadip Basu
- Department of Computer Science and Engineering, Jadvapur University, Kolkata 700032, India;
| | - Jakub Włodarczyk
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
| | - Błażej Ruszczycki
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; (E.B.); (K.K.P.); (J.W.)
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12
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Imaging of spine synapses using super-resolution microscopy. Anat Sci Int 2021; 96:343-358. [PMID: 33459976 DOI: 10.1007/s12565-021-00603-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 01/04/2021] [Indexed: 12/17/2022]
Abstract
Neuronal circuits in the neocortex and hippocampus are essential for higher brain functions such as motor learning and spatial memory. In the mammalian forebrain, most excitatory synapses of pyramidal neurons are formed on spines, which are tiny protrusions extending from the dendritic shaft. The spine contains specialized molecular machinery that regulates synaptic transmission and plasticity. Spine size correlates with the efficacy of synaptic transmission, and spine morphology affects signal transduction at the post-synaptic compartment. Plasticity-related changes in the structural and molecular organization of spine synapses are thought to underlie the cellular basis of learning and memory. Recent advances in super-resolution microscopy have revealed the molecular mechanisms of the nanoscale synaptic structures regulating synaptic transmission and plasticity in living neurons, which are difficult to investigate using electron microscopy alone. In this review, we summarize recent advances in super-resolution imaging of spine synapses and discuss the implications of nanoscale structures in the regulation of synaptic function, learning, and memory.
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13
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Henneberger C, Bard L, Panatier A, Reynolds JP, Kopach O, Medvedev NI, Minge D, Herde MK, Anders S, Kraev I, Heller JP, Rama S, Zheng K, Jensen TP, Sanchez-Romero I, Jackson CJ, Janovjak H, Ottersen OP, Nagelhus EA, Oliet SHR, Stewart MG, Nägerl UV, Rusakov DA. LTP Induction Boosts Glutamate Spillover by Driving Withdrawal of Perisynaptic Astroglia. Neuron 2020; 108:919-936.e11. [PMID: 32976770 PMCID: PMC7736499 DOI: 10.1016/j.neuron.2020.08.030] [Citation(s) in RCA: 131] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 06/14/2020] [Accepted: 08/28/2020] [Indexed: 02/07/2023]
Abstract
Extrasynaptic actions of glutamate are limited by high-affinity transporters expressed by perisynaptic astroglial processes (PAPs): this helps maintain point-to-point transmission in excitatory circuits. Memory formation in the brain is associated with synaptic remodeling, but how this affects PAPs and therefore extrasynaptic glutamate actions is poorly understood. Here, we used advanced imaging methods, in situ and in vivo, to find that a classical synaptic memory mechanism, long-term potentiation (LTP), triggers withdrawal of PAPs from potentiated synapses. Optical glutamate sensors combined with patch-clamp and 3D molecular localization reveal that LTP induction thus prompts spatial retreat of astroglial glutamate transporters, boosting glutamate spillover and NMDA-receptor-mediated inter-synaptic cross-talk. The LTP-triggered PAP withdrawal involves NKCC1 transporters and the actin-controlling protein cofilin but does not depend on major Ca2+-dependent cascades in astrocytes. We have therefore uncovered a mechanism by which a memory trace at one synapse could alter signal handling by multiple neighboring connections.
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Affiliation(s)
- Christian Henneberger
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK; Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), 53175 Bonn, Germany.
| | - Lucie Bard
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Aude Panatier
- INSERM U1215, Neurocentre Magendie, 33000 Bordeaux, France; Université de Bordeaux, 33000 Bordeaux, France; Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France
| | - James P Reynolds
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Olga Kopach
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | | | - Daniel Minge
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Michel K Herde
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Stefanie Anders
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Igor Kraev
- Life Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Janosch P Heller
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Sylvain Rama
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Kaiyu Zheng
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Thomas P Jensen
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | | | - Colin J Jackson
- Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia
| | - Harald Janovjak
- Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria; EMBL Australia, Australian Regenerative Medicine Institute, Faculty of Medicine, Nursing and Health Science, Monash University, Melbourne, VIC 3800, Australia
| | - Ole Petter Ottersen
- Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway; Karolinska Institutet, 171 77 Stockholm, Sweden
| | | | - Stephane H R Oliet
- INSERM U1215, Neurocentre Magendie, 33000 Bordeaux, France; Université de Bordeaux, 33000 Bordeaux, France
| | | | - U Valentin Nägerl
- Université de Bordeaux, 33000 Bordeaux, France; Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, 33000 Bordeaux, France.
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK.
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14
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Motor learning induces plastic changes in Purkinje cell dendritic spines in the rat cerebellum. NEUROLOGÍA (ENGLISH EDITION) 2020. [DOI: 10.1016/j.nrleng.2019.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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15
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Streffing-Hellhake P, Luft A, Hosp J. Motor Learning Induces Profound but Delayed Dendritic Plasticity in M1 Layer II/III Pyramidal Neurons. Neuroscience 2020; 442:17-28. [DOI: 10.1016/j.neuroscience.2020.06.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 10/23/2022]
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Soriano D, Vacotto M, Brusco A, Caltana L. Neuronal and synaptic morphological alterations in the hippocampus of cannabinoid receptor type 1 knockout mice. J Neurosci Res 2020; 98:2245-2262. [DOI: 10.1002/jnr.24694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 05/28/2020] [Accepted: 06/27/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Delia Soriano
- Universidad de Buenos Aires. Facultad de Medicina. 1° Unidad Académica del Departamento de Histología, Embriología, Biología Celular y Genética. Buenos Aires. Argentina. Buenos Aires Argentina
- Instituto de Biología Celular y Neurociencia Prof. E. De Robertis (IBCN) CONICET‐Universidad de Buenos Aires Buenos Aires Argentina
| | - Marina Vacotto
- Instituto de Biología Celular y Neurociencia Prof. E. De Robertis (IBCN) CONICET‐Universidad de Buenos Aires Buenos Aires Argentina
| | - Alicia Brusco
- Universidad de Buenos Aires. Facultad de Medicina. 1° Unidad Académica del Departamento de Histología, Embriología, Biología Celular y Genética. Buenos Aires. Argentina. Buenos Aires Argentina
- Instituto de Biología Celular y Neurociencia Prof. E. De Robertis (IBCN) CONICET‐Universidad de Buenos Aires Buenos Aires Argentina
| | - Laura Caltana
- Universidad de Buenos Aires. Facultad de Medicina. 1° Unidad Académica del Departamento de Histología, Embriología, Biología Celular y Genética. Buenos Aires. Argentina. Buenos Aires Argentina
- Instituto de Biología Celular y Neurociencia Prof. E. De Robertis (IBCN) CONICET‐Universidad de Buenos Aires Buenos Aires Argentina
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Cambiaghi M, Crupi R, Bautista EL, Elsamadisi A, Malik W, Pozdniakova H, Han Z, Buffelli M, Battaglia F. The Effects of 1-Hz rTMS on Emotional Behavior and Dendritic Complexity of Mature and Newly Generated Dentate Gyrus Neurons in Male Mice. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17114074. [PMID: 32521613 PMCID: PMC7312937 DOI: 10.3390/ijerph17114074] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/14/2022]
Abstract
Low-frequency repetitive transcranial magnetic stimulation (1-Hz rTMS) is a promising noninvasive tool for the treatment of depression. Hippocampal neuronal plasticity is thought to play a pivotal role in the pathophysiology of depressive disorders and the mechanism of action of antidepressant treatments. We investigated the effect of 1-Hz rTMS treatment on hippocampal dentate gyrus structural plasticity and related emotional behaviors modifications. Experimentally, adult male mice received either five days of 1-Hz rTMS or Sham stimulation. After stimulation, the mice underwent a battery of tests for anxiety-like and depression-like behaviors. We also tested the effect of treatment on mature and newly generated granule cell dendritic complexity. Our data showed that 1-Hz rTMS induced structural plasticity in mature granule cells, as evidenced by increased dendritic length and number of intersections. However, the stimulation did not increase the proliferation of the dentate gyrus progenitor cells. On the contrary, the stimulated mice showed increased dendritic complexity of newly generated neurons. Moreover, 1-Hz rTMS resulted in antidepressant-like effects in the tail suspension test, but it did not affect anxiety-like behaviors. Therefore, our results indicate that 1-Hz rTMS modulates dentate gyrus morphological plasticity in mature and newly generated neurons. Furthermore, our data provide some evidence of an association between the antidepressant-like activity of 1-Hz rTMS and structural plasticity in the hippocampus.
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Affiliation(s)
- Marco Cambiaghi
- Department of Neurosciences, Biomedicine and Movement Sciences-University of Verona, 37134 Verona, Italy; (M.C.); (M.B.)
| | - Rosalia Crupi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98125 Messina, Italy;
| | - Erick Larios Bautista
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
| | - Amir Elsamadisi
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
| | - Wasib Malik
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
| | - Helen Pozdniakova
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
| | - Zhiyong Han
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
| | - Mario Buffelli
- Department of Neurosciences, Biomedicine and Movement Sciences-University of Verona, 37134 Verona, Italy; (M.C.); (M.B.)
| | - Fortunato Battaglia
- Department of Medical Sciences, Neurology and Psychiatry, Hackensack Meridian School of Medicine, Seton Hall University, Nutley, NJ 07110, USA; (E.L.B.); (A.E.); (W.M.); (H.P.); (Z.H.)
- Correspondence: ; Tel.: +97-3761-9605
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18
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Ultrastructure of light-activated axons following optogenetic stimulation to produce late-phase long-term potentiation. PLoS One 2020; 15:e0226797. [PMID: 31940316 PMCID: PMC6961864 DOI: 10.1371/journal.pone.0226797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/04/2019] [Indexed: 12/03/2022] Open
Abstract
Analysis of neuronal compartments has revealed many state-dependent changes in geometry but establishing synapse-specific mechanisms at the nanoscale has proven elusive. We co-expressed channelrhodopsin2-GFP and mAPEX2 in a subset of hippocampal CA3 neurons and used trains of light to induce late-phase long-term potentiation (L-LTP) in area CA1. L-LTP was shown to be specific to the labeled axons by severing CA3 inputs, which prevented back-propagating recruitment of unlabeled axons. Membrane-associated mAPEX2 tolerated microwave-enhanced chemical fixation and drove tyramide signal amplification to deposit Alexa Fluor dyes in the light-activated axons. Subsequent post-embedding immunogold labeling resulted in outstanding ultrastructure and clear distinctions between labeled (activated), and unlabeled axons without obscuring subcellular organelles. The gold-labeled axons in potentiated slices were reconstructed through serial section electron microscopy; presynaptic vesicles and other constituents could be quantified unambiguously. The genetic specification, reliable physiology, and compatibility with established methods for ultrastructural preservation make this an ideal approach to link synapse ultrastructure and function in intact circuits.
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19
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Multi-input Synapses, but Not LTP-Strengthened Synapses, Correlate with Hippocampal Memory Storage in Aged Mice. Curr Biol 2019; 29:3600-3610.e4. [PMID: 31630953 PMCID: PMC6839404 DOI: 10.1016/j.cub.2019.08.064] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/05/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022]
Abstract
Long-lasting changes at synapses enable memory storage in the brain. Although aging is associated with impaired memory formation, it is not known whether the synaptic underpinnings of memory storage differ with age. Using a training schedule that results in the same behavioral memory formation in young and aged mice, we examined synapse ultrastructure and molecular signaling in the hippocampus after contextual fear conditioning. Only in young, but not old mice, contextual fear memory formation was associated with synaptic changes that characterize well-known, long-term potentiation, a strengthening of existing synapses with one input. Instead, old-age memory was correlated with generation of multi-innervated dendritic spines (MISs), which are predominantly two-input synapses formed by the attraction of an additional excitatory, presynaptic terminal onto an existing synapse. Accordingly, a blocker used to inhibit MIS generation impaired contextual fear memory only in old mice. Our results reveal how the synaptic basis of hippocampal memory storage changes with age and suggest that these distinct memory-storing mechanisms may explain impaired updating in old age. Aged mice form contextual memory like young mice, but reconsolidation is impaired Only in young mice is contextual memory formation associated with structural LTP In aged mice, contextual memory formation correlates with multi-innervated spines Inhibition of multi-innervated spines impairs memory in aged but not young mice
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Sleep Deprivation by Exposure to Novel Objects Increases Synapse Density and Axon-Spine Interface in the Hippocampal CA1 Region of Adolescent Mice. J Neurosci 2019; 39:6613-6625. [PMID: 31263066 DOI: 10.1523/jneurosci.0380-19.2019] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/24/2019] [Accepted: 06/10/2019] [Indexed: 11/21/2022] Open
Abstract
Sleep has been hypothesized to rebalance overall synaptic strength after ongoing learning during waking leads to net synaptic potentiation. If so, because synaptic strength and size are correlated, synapses on average should be larger after wake and smaller after sleep. This prediction was recently confirmed in mouse cerebral cortex using serial block-face electron microscopy (SBEM). However, whether these findings extend to other brain regions is unknown. Moreover, sleep deprivation by gentle handling was reported to produce hippocampal spine loss, raising the question of whether synapse size and number are differentially affected by sleep and waking. Here we applied SBEM to measure axon-spine interface (ASI), the contact area between pre-synapse and post-synapse, and synapse density in CA1 stratum radiatum. Adolescent YFP-H mice were studied after 6-8 h of sleep (S = 6), spontaneous wake at night (W = 4) or wake enforced during the day by novelty exposure (EW = 4; males/females balanced). In each animal ≥425 ASIs were measured and synaptic vesicles were counted in ~100 synapses/mouse. Reconstructed dendrites included many small, nonperforated synapses and fewer large, perforated synapses. Relative to S, ASI sizes in perforated synapses shifted toward higher values after W and more so after EW. ASI sizes in nonperforated synapses grew after EW relative to S and W, and so did their density. ASI size correlated with presynaptic vesicle number but the proportion of readily available vesicles decreased after EW, suggesting presynaptic fatigue. Thus, CA1 synapses undergo changes consistent with sleep-dependent synaptic renormalization and their number increases after extended wake.SIGNIFICANCE STATEMENT Sleep benefits learning, memory consolidation, and the integration of new with old memories, but the underlying mechanisms remain highly debated. One hypothesis suggests that sleep's cognitive benefits stem from its ability to renormalize total synaptic strength, after ongoing learning during wake leads to net synaptic potentiation. Supporting evidence for this hypothesis mainly comes from the cerebral cortex, including the observation that cortical synapses are larger after wake and smaller after sleep. Using serial electron microscopy, we find here that sleep/wake synaptic changes consistent with sleep-dependent synaptic renormalization also occur in the CA1 region. Thus, the role of sleep in maintaining synaptic homeostasis may extend to the hippocampus, a key area for learning and synaptic plasticity.
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Chidambaram SB, Rathipriya AG, Bolla SR, Bhat A, Ray B, Mahalakshmi AM, Manivasagam T, Thenmozhi AJ, Essa MM, Guillemin GJ, Chandra R, Sakharkar MK. Dendritic spines: Revisiting the physiological role. Prog Neuropsychopharmacol Biol Psychiatry 2019; 92:161-193. [PMID: 30654089 DOI: 10.1016/j.pnpbp.2019.01.005] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 01/04/2019] [Accepted: 01/12/2019] [Indexed: 12/11/2022]
Abstract
Dendritic spines are small, thin, specialized protrusions from neuronal dendrites, primarily localized in the excitatory synapses. Sophisticated imaging techniques revealed that dendritic spines are complex structures consisting of a dense network of cytoskeletal, transmembrane and scaffolding molecules, and numerous surface receptors. Molecular signaling pathways, mainly Rho and Ras family small GTPases pathways that converge on actin cytoskeleton, regulate the spine morphology and dynamics bi-directionally during synaptic activity. During synaptic plasticity the number and shapes of dendritic spines undergo radical reorganizations. Long-term potentiation (LTP) induction promote spine head enlargement and the formation and stabilization of new spines. Long-term depression (LTD) results in their shrinkage and retraction. Reports indicate increased spine density in the pyramidal neurons of autism and Fragile X syndrome patients and reduced density in the temporal gyrus loci of schizophrenic patients. Post-mortem reports of Alzheimer's brains showed reduced spine number in the hippocampus and cortex. This review highlights the spine morphogenesis process, the activity-dependent structural plasticity and mechanisms by which synaptic activity sculpts the dendritic spines, the structural and functional changes in spines during learning and memory using LTP and LTD processes. It also discusses on spine status in neurodegenerative diseases and the impact of nootropics and neuroprotective agents on the functional restoration of dendritic spines.
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Affiliation(s)
- Saravana Babu Chidambaram
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India.
| | - A G Rathipriya
- Food and Brain Research Foundation, Chennai, Tamil Nadu, India
| | - Srinivasa Rao Bolla
- Department of Anatomy, College of Medicine, Imam Abdulrahman Bin Faisal University, Damam, Saudi Arabia
| | - Abid Bhat
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Bipul Ray
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Arehally Marappa Mahalakshmi
- Department of Pharmacology, JSS College of Pharmacy, JSS Academy of Higher Education & Research (JSSAHER), Mysuru, Karnataka 570015, India
| | - Thamilarasan Manivasagam
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Arokiasamy Justin Thenmozhi
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamilnadu, India
| | - Musthafa Mohamed Essa
- Department of Food Science and Nutrition, CAMS, Sultan Qaboos University, Muscat, Oman
| | - Gilles J Guillemin
- Neuropharmacology Group, Faculty of Medicine and Health Sciences, Deb Bailey MND Research Laboratory, Macquarie University, Sydney, NSW 2109, Australia
| | - Ramesh Chandra
- Department of Chemistry, Ambedkar Centre for BioMedical Research, Delhi University, Delhi 110007, India
| | - Meena Kishore Sakharkar
- College of Pharmacy and Nutrition, University of Saskatchewan, 107, Wiggins Road, Saskatoon, SK S7N 5C9, Canada.
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22
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Borczyk M, Śliwińska MA, Caly A, Bernas T, Radwanska K. Neuronal plasticity affects correlation between the size of dendritic spine and its postsynaptic density. Sci Rep 2019; 9:1693. [PMID: 30737431 PMCID: PMC6368589 DOI: 10.1038/s41598-018-38412-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 11/19/2018] [Indexed: 01/23/2023] Open
Abstract
Structural plasticity of dendritic spines is thought to underlie memory formation. Size of a dendritic spine is considered proportional to the size of its postsynaptic density (PSD), number of glutamate receptors and synaptic strength. However, whether this correlation is true for all dendritic spine volumes, and remains stable during synaptic plasticity, is largely unknown. In this study, we take advantage of 3D electron microscopy and reconstruct dendritic spines and cores of PSDs from the stratum radiatum of the area CA1 of organotypic hippocampal slices. We observe that approximately 1/3 of dendritic spines, in a range of medium sizes, fail to reach significant correlation between dendritic spine volume and PSD surface area or PSD-core volume. During NMDA receptor-dependent chemical long-term potentiation (NMDAR-cLTP) dendritic spines and their PSD not only grow, but also PSD area and PSD-core volume to spine volume ratio is increased, and the correlation between the sizes of these two is tightened. Further analysis specified that only spines that contain smooth endoplasmic reticulum (SER) grow during cLTP, while PSD-cores grow irrespectively of the presence of SER in the spine. Dendritic spines with SER also show higher correlation of the volumetric parameters than spines without SER, and this correlation is further increased during cLTP only in the spines that contain SER. Overall, we found that correlation between PSD surface area and spine volume is not consistent across all spine volumes, is modified and tightened during synaptic plasticity and regulated by SER.
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Affiliation(s)
- Malgorzata Borczyk
- Laboratory of Molecular Basis of Behavior, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland
| | - Małgorzata Alicja Śliwińska
- Laboratory of Molecular Basis of Behavior, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland.,Laboratory of Imaging Tissue Structure and Function, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland
| | - Anna Caly
- Laboratory of Molecular Basis of Behavior, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland
| | - Tytus Bernas
- Laboratory of Imaging Tissue Structure and Function, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland
| | - Kasia Radwanska
- Laboratory of Molecular Basis of Behavior, the Nencki Institute of Experimental Biology of Polish Academy of Sciences, ul. L. Pasteura 3, Warsaw, 02-093, Poland.
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23
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Seibt J, Frank MG. Primed to Sleep: The Dynamics of Synaptic Plasticity Across Brain States. Front Syst Neurosci 2019; 13:2. [PMID: 30774586 PMCID: PMC6367653 DOI: 10.3389/fnsys.2019.00002] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 01/09/2019] [Indexed: 11/13/2022] Open
Abstract
It is commonly accepted that brain plasticity occurs in wakefulness and sleep. However, how these different brain states work in concert to create long-lasting changes in brain circuitry is unclear. Considering that wakefulness and sleep are profoundly different brain states on multiple levels (e.g., cellular, molecular and network activation), it is unlikely that they operate exactly the same way. Rather it is probable that they engage different, but coordinated, mechanisms. In this article we discuss how plasticity may be divided across the sleep-wake cycle, and how synaptic changes in each brain state are linked. Our working model proposes that waking experience triggers short-lived synaptic events that are necessary for transient plastic changes and mark (i.e., 'prime') circuits and synapses for further processing in sleep. During sleep, synaptic protein synthesis at primed synapses leads to structural changes necessary for long-term information storage.
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Affiliation(s)
- Julie Seibt
- Surrey Sleep Research Centre, University of Surrey, Guildford, United Kingdom
| | - Marcos G. Frank
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University Spokane, Spokane, WA, United States
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24
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Heller JP, Rusakov DA. A Method to Visualize the Nanoscopic Morphology of Astrocytes In Vitro and In Situ. Methods Mol Biol 2019; 1938:69-84. [PMID: 30617973 DOI: 10.1007/978-1-4939-9068-9_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In recent years it has become apparent that astroglia are not only essential players in brain development, homeostasis, and metabolic support but are also important for the formation and regulation of synaptic circuits. Fine astrocytic processes that can be found in the vicinity of synapses undergo considerable structural plasticity associated with age- and use-dependent changes in neural circuitries. However, due to the extraordinary complex, essentially nanoscopic morphology of astroglia, the underlying cellular mechanisms remain poorly understood.Here we detail a super-resolution microscopy approach, based on the single-molecule localisation microscopy (SMLM) technique direct stochastic optical reconstruction microscopy (dSTORM) to visualize astroglial morphology on the nanoscale. This approach enables visualization of key morphological changes that occur in nanoscopic astrocyte processes, whose characteristic size falls below the diffraction limit of conventional optical microscopy.
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Affiliation(s)
- Janosch P Heller
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, UK.
| | - Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, UK.
- Laboratory of Brain Microcircuits, Institute of Neuroscience, University of Nizhny Novgorod, Nizhny Novgorod, Russia.
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25
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Masch JM, Steffens H, Fischer J, Engelhardt J, Hubrich J, Keller-Findeisen J, D'Este E, Urban NT, Grant SGN, Sahl SJ, Kamin D, Hell SW. Robust nanoscopy of a synaptic protein in living mice by organic-fluorophore labeling. Proc Natl Acad Sci U S A 2018; 115:E8047-E8056. [PMID: 30082388 PMCID: PMC6112726 DOI: 10.1073/pnas.1807104115] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Extending superresolution fluorescence microscopy to living animals has remained a challenging frontier ever since the first demonstration of STED (stimulated emission depletion) nanoscopy in the mouse visual cortex. The use of fluorescent proteins (FPs) in in vivo STED analyses has been limiting available fluorescence photon budgets and attainable image contrasts, in particular for far-red FPs. This has so far precluded the definition of subtle details in protein arrangements at sufficient signal-to-noise ratio. Furthermore, imaging with longer wavelengths holds promise for reducing photostress. Here, we demonstrate that a strategy based on enzymatic self-labeling of the HaloTag fusion protein by high-performance synthetic fluorophore labels provides a robust avenue to superior in vivo analysis with STED nanoscopy in the far-red spectral range. We illustrate our approach by mapping the nanoscale distributions of the abundant scaffolding protein PSD95 at the postsynaptic membrane of excitatory synapses in living mice. With silicon-rhodamine as the reporter fluorophore, we present imaging with high contrast and low background down to ∼70-nm lateral resolution in the visual cortex at ≤25-µm depth. This approach allowed us to identify and characterize the diversity of PSD95 scaffolds in vivo. Besides small round/ovoid shapes, a substantial fraction of scaffolds exhibited a much more complex spatial organization. This highly inhomogeneous, spatially extended PSD95 distribution within the disk-like postsynaptic density, featuring intricate perforations, has not been highlighted in cell- or tissue-culture experiments. Importantly, covisualization of the corresponding spine morphologies enabled us to contextualize the diverse PSD95 patterns within synapses of different orientations and sizes.
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Affiliation(s)
- Jennifer-Magdalena Masch
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany
| | - Heinz Steffens
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Joachim Fischer
- Optical Nanoscopy Division, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Johann Engelhardt
- Optical Nanoscopy Division, German Cancer Research Center, 69120 Heidelberg, Germany
- Department of Optical Nanoscopy, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Jasmine Hubrich
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Jan Keller-Findeisen
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Elisa D'Este
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Nicolai T Urban
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany
| | - Seth G N Grant
- Centre for Clinical Brain Sciences, The University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - Steffen J Sahl
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Dirk Kamin
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany;
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany
| | - Stefan W Hell
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany;
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, 37073 Göttingen, Germany
- Optical Nanoscopy Division, German Cancer Research Center, 69120 Heidelberg, Germany
- Department of Optical Nanoscopy, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
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26
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Structural homo- and heterosynaptic plasticity in mature and adult newborn rat hippocampal granule cells. Proc Natl Acad Sci U S A 2018; 115:E4670-E4679. [PMID: 29712871 DOI: 10.1073/pnas.1801889115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adult newborn hippocampal granule cells (abGCs) contribute to spatial learning and memory. abGCs are thought to play a specific role in pattern separation, distinct from developmentally born mature GCs (mGCs). Here we examine at which exact cell age abGCs are synaptically integrated into the adult network and which forms of synaptic plasticity are expressed in abGCs and mGCs. We used virus-mediated labeling of abGCs and mGCs to analyze changes in spine morphology as an indicator of plasticity in rats in vivo. High-frequency stimulation of the medial perforant path induced long-term potentiation in the middle molecular layer (MML) and long-term depression in the nonstimulated outer molecular layer (OML). This stimulation protocol elicited NMDA receptor-dependent homosynaptic spine enlargement in the MML and heterosynaptic spine shrinkage in the inner molecular layer and OML. Both processes were concurrently present on individual dendritic trees of abGCs and mGCs. Spine shrinkage counteracted spine enlargement and thus could play a homeostatic role, normalizing synaptic weights. Structural homosynaptic spine plasticity had a clear onset, appearing in abGCs by 28 d postinjection (dpi), followed by heterosynaptic spine plasticity at 35 dpi, and at 77 dpi was equally as present in mature abGCs as in mGCs. From 35 dpi on, about 60% of abGCs and mGCs showed significant homo- and heterosynaptic plasticity on the single-cell level. This demonstration of structural homo- and heterosynaptic plasticity in abGCs and mGCs defines the time course of the appearance of synaptic plasticity and integration for abGCs.
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27
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Mitochondrial Ultrastructure Is Coupled to Synaptic Performance at Axonal Release Sites. eNeuro 2018; 5:eN-NWR-0390-17. [PMID: 29383328 PMCID: PMC5788698 DOI: 10.1523/eneuro.0390-17.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/28/2017] [Accepted: 01/06/2018] [Indexed: 01/08/2023] Open
Abstract
Mitochondrial function in neurons is tightly linked with metabolic and signaling mechanisms that ultimately determine neuronal performance. The subcellular distribution of these organelles is dynamically regulated as they are directed to axonal release sites on demand, but whether mitochondrial internal ultrastructure and molecular properties would reflect the actual performance requirements in a synapse-specific manner, remains to be established. Here, we examined performance-determining ultrastructural features of presynaptic mitochondria in GABAergic and glutamatergic axons of mice and human. Using electron-tomography and super-resolution microscopy we found, that these features were coupled to synaptic strength: mitochondria in boutons with high synaptic activity exhibited an ultrastructure optimized for high rate metabolism and contained higher levels of the respiratory chain protein cytochrome-c (CytC) than mitochondria in boutons with lower activity. The strong, cell type-independent correlation between mitochondrial ultrastructure, molecular fingerprints and synaptic performance suggests that changes in synaptic activity could trigger ultrastructural plasticity of presynaptic mitochondria, likely to adjust their performance to the actual metabolic demand.
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Wegner W, Mott AC, Grant SGN, Steffens H, Willig KI. In vivo STED microscopy visualizes PSD95 sub-structures and morphological changes over several hours in the mouse visual cortex. Sci Rep 2018; 8:219. [PMID: 29317733 PMCID: PMC5760696 DOI: 10.1038/s41598-017-18640-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 12/14/2017] [Indexed: 12/23/2022] Open
Abstract
The post-synaptic density (PSD) is an electron dense region consisting of ~1000 proteins, found at the postsynaptic membrane of excitatory synapses, which varies in size depending upon synaptic strength. PSD95 is an abundant scaffolding protein in the PSD and assembles a family of supercomplexes comprised of neurotransmitter receptors, ion channels, as well as signalling and structural proteins. We use superresolution STED (STimulated Emission Depletion) nanoscopy to determine the size and shape of PSD95 in the anaesthetised mouse visual cortex. Adult knock-in mice expressing eGFP fused to the endogenous PSD95 protein were imaged at time points from 1 min to 6 h. Superresolved large assemblies of PSD95 show different sub-structures; most large assemblies were ring-like, some horse-shoe or figure-8 shaped, and shapes were continuous or made up of nanoclusters. The sub-structure appeared stable during the shorter (minute) time points, but after 1 h, more than 50% of the large assemblies showed a change in sub-structure. Overall, these data showed a sub-morphology of large PSD95 assemblies which undergo changes within the 6 hours of observation in the anaesthetised mouse.
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Affiliation(s)
- Waja Wegner
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Alexander C Mott
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.,Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Seth G N Grant
- Genes to Cognition Program, Centre for Clinical Brain Sciences, Chancellor's Building, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Heinz Steffens
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany.,Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Katrin I Willig
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany. .,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany. .,Max Planck Institute of Experimental Medicine, Göttingen, Germany.
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González-Tapia D, González-Ramírez MM, Vázquez-Hernández N, González-Burgos I. Motor learning induces plastic changes in Purkinje cell dendritic spines in the rat cerebellum. Neurologia 2017; 35:451-457. [PMID: 29249302 DOI: 10.1016/j.nrl.2017.10.007] [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: 09/12/2017] [Accepted: 10/10/2017] [Indexed: 10/18/2022] Open
Abstract
INTRODUCTION The paramedian lobule of the cerebellum is involved in learning to correctly perform motor skills through practice. Dendritic spines are dynamic structures that regulate excitatory synaptic stimulation. We studied plastic changes occurring in the dendritic spines of Purkinje cells from the paramedian lobule of rats during motor learning. METHODS Adult male rats were trained over a 6-day period using an acrobatic motor learning paradigm; the density and type of dendritic spines were determined every day during the study period using a modified version of the Golgi method. RESULTS The learning curve reflected a considerable decrease in the number of errors made by rats as the training period progressed. We observed more dendritic spines on days 2 and 6, particularly more thin spines on days 1, 3, and 6, fewer mushroom spines on day 3, fewer stubby spines on day 1, and more thick spines on days 4 and 6. CONCLUSION The initial stage of motor learning may be associated with fast processing of the underlying synaptic information combined with an apparent "silencing" of memory consolidation processes, based on the regulation of the neuronal excitability.
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Affiliation(s)
- D González-Tapia
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jalisco, México; Universidad Politécnica de la Zona Metropolitana de Guadalajara, Tlajomulco de Zúñiga, Jalisco, México; Instituto de Ciencias de la Rehabilitación Integral, Guadalajara, Jalisco, México
| | - M M González-Ramírez
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jalisco, México
| | - N Vázquez-Hernández
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jalisco, México
| | - I González-Burgos
- División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS, Guadalajara, Jalisco, México.
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Chen F, Ardalan M, Elfving B, Wegener G, Madsen TM, Nyengaard JR. Mitochondria Are Critical for BDNF-Mediated Synaptic and Vascular Plasticity of Hippocampus following Repeated Electroconvulsive Seizures. Int J Neuropsychopharmacol 2017; 21:291-304. [PMID: 29228215 PMCID: PMC5838811 DOI: 10.1093/ijnp/pyx115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 12/05/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Electroconvulsive therapy is a fast-acting and efficient treatment of depression used in the clinic. The underlying mechanism of its therapeutic effect is still unclear. However, recovery of synaptic connections and synaptic remodeling is thought to play a critical role for the clinical efficacy obtained from a rapid antidepressant response. Here, we investigated the relationship between synaptic changes and concomitant nonneuronal changes in microvasculature and mitochondria and its relationship to brain-derived neurotrophic factor level changes after repeated electroconvulsive seizures, an animal model of electroconvulsive therapy. METHODS Electroconvulsive seizures or sham treatment was given daily for 10 days to rats displaying a genetically driven phenotype modelling clinical depression: the Flinders Sensitive and Resistant Line rats. Stereological principles were employed to quantify numbers of synapses and mitochondria, and the length of microvessels in the hippocampus. The brain-derived neurotrophic factor protein levels were quantified with immunohistochemistry. RESULTS In untreated controls, a lower number of synapses and mitochondria was accompanied by shorter microvessels of the hippocampus in "depressive" phenotype (Flinders Sensitive Line) compared with the "nondepressed" phenotype (Flinders Resistant Line). Electroconvulsive seizure administration significantly increased the number of synapses and mitochondria, and length of microvessels both in Flinders Sensitive Line-electroconvulsive seizures and Flinders Resistant Line-electroconvulsive seizures rats. In addition, the amount of brain-derived neurotrophic factor protein was significantly increased in Flinders Sensitive Line and Flinders Resistant Line rats after electroconvulsive seizures. Furthermore, there was a significant positive correlation between brain-derived neurotrophic factor level and mitochondria/synapses. CONCLUSION Our results indicate that rapid and efficient therapeutic effect of electroconvulsive seizures may be related to synaptic plasticity, accompanied by brain-derived neurotrophic factor protein level elevation and mitochondrial and vascular support.
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Affiliation(s)
- Fenghua Chen
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Correspondence: Fenghua Chen, MD, PhD, Department of Clinical Medicine, Translational Neuropsychiatry Unit, Skovagervej 2, building 14K, 0.15, 8240 Risskov, Denmark ()
| | - Maryam Ardalan
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark,Center of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa,Department of Clinical Medicine, Center of Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark
| | - Betina Elfving
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | - Gregers Wegener
- AUGUST Centre, Department of Clinical Medicine, Aarhus University, Risskov, Denmark
| | | | - Jens R Nyengaard
- Core Center for Molecular Morphology, Section for Stereology and Microscopy, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark,Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark
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Heller JP, Michaluk P, Sugao K, Rusakov DA. Probing nano-organization of astroglia with multi-color super-resolution microscopy. J Neurosci Res 2017; 95:2159-2171. [PMID: 28151556 DOI: 10.1002/jnr.24026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/12/2016] [Accepted: 12/28/2016] [Indexed: 01/04/2023]
Abstract
Astroglia are essential for brain development, homeostasis, and metabolic support. They also contribute actively to the formation and regulation of synaptic circuits, by successfully handling, integrating, and propagating physiological signals of neural networks. The latter occurs mainly by engaging a versatile mechanism of internal Ca2+ fluctuations and regenerative waves prompting targeted release of signaling molecules into the extracellular space. Astroglia also show substantial structural plasticity associated with age- and use-dependent changes in neural circuitry. However, the underlying cellular mechanisms are poorly understood, mainly because of the extraordinary complex morphology of astroglial compartments on the nanoscopic scale. This complexity largely prevents direct experimental access to astroglial processes, most of which are beyond the diffraction limit of optical microscopy. Here we employed super-resolution microscopy (direct stochastic optical reconstruction microscopy; dSTORM), to visualize astroglial organization on the nanoscale, in culture and in thin brain slices, as an initial step to understand the structural basis of astrocytic nano-physiology. We were able to follow nanoscopic morphology of GFAP-enriched astrocytes, which adapt a flattened shape in culture and a sponge-like structure in situ, with GFAP fibers of varied diameters. We also visualized nanoscopic astrocytic processes using the ubiquitous cytosolic astrocyte marker proteins S100β and glutamine synthetase. Finally, we overexpressed and imaged membrane-targeted pHluorin and lymphocyte-specific protein tyrosine kinase (N-terminal domain) -green fluorescent protein (lck-GFP), to better understand the molecular cascades underlying some common astroglia-targeted fluorescence imaging techniques. The results provide novel, albeit initial, insights into the cellular organization of astroglia on the nanoscale, paving the way for function-specific studies. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Janosch P Heller
- UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom
| | - Piotr Michaluk
- UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom
| | - Kohtaroh Sugao
- UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom.,Molecular Pathophysiology Research, Drug Research Division, Sumitomo Dainippon Pharma Co., Ltd., Tokyo, 104-8356, Japan
| | - Dmitri A Rusakov
- UCL Institute of Neurology, Department of Clinical and Experimental Epilepsy, Queen Square House, London WC1N 3BG, United Kingdom
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Ardalan M, Wegener G, Rafati AH, Nyengaard JR. S-Ketamine Rapidly Reverses Synaptic and Vascular Deficits of Hippocampus in Genetic Animal Model of Depression. Int J Neuropsychopharmacol 2016; 20:247-256. [PMID: 27815416 PMCID: PMC5408982 DOI: 10.1093/ijnp/pyw098] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 11/02/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The neurovascular plasticity of hippocampus is an important theory underlying major depression. Ketamine as a novel glutamatergic antidepressant drug can induce a rapid antidepressant effect within hours. In a mechanistic proof of this concept, we examined whether ketamine leads to an increase in synaptogenesis and vascularization within 24 hours after a single injection in a genetic rat model of depression. METHODS Flinders Sensitive Line and Flinders Resistant Line rats were given a single intraperitoneal injection of ketamine (15 mg/kg) or saline. One day later, their behavior was evaluated by a modified forced swim test. Microvessel length was evaluated with global spatial sampling and optical microscopy, whereas the number of asymmetric synapses was quantified through serial section electron microscopy by using physical disector method in the CA1.stratum radiatum area of hippocampus. RESULTS The immobility time in the forced swim test among Flinders Sensitive Line rats with ketamine treatment was significantly lower compared with Flinders Sensitive Line rats without treatment. The number of nonperforated and perforated synapses was significantly higher in the Flinders Sensitive Line-ketamine vs the Flinders Sensitive Line-vehicle group; however, ketamine did not induce a significant increase in the number of shaft synapses. Additionally, total length of microvessels was significantly increased 1 day after ketamine treatment in Flinders Sensitive Line rats in the hippocampal subregions, including the CA1.stratum radiatum. CONCLUSION Our findings indicate that hippocampal vascularization and synaptogenesis is co-regulated rapidly after ketamine, and microvascular elongation may be a supportive factor for synaptic plasticity and neuronal activity. These findings go hand-in-hand with the behavioral observations, where ketamine acts as a potent antidepressant.
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Affiliation(s)
- Maryam Ardalan
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark (Drs Ardalan and Wegener); Stereology and Electron Microscopy Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark (Drs Ardalan, Rafati, and Nyengaard); Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark (Drs Rafati and Nyengaard); Pharmaceutical Research Center of Excellence, School of Pharmacy (Pharmacology), North-West University, Potchefstroom, South Africa (Dr Wegener)
| | - Gregers Wegener
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark (Drs Ardalan and Wegener); Stereology and Electron Microscopy Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark (Drs Ardalan, Rafati, and Nyengaard); Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark (Drs Rafati and Nyengaard); Pharmaceutical Research Center of Excellence, School of Pharmacy (Pharmacology), North-West University, Potchefstroom, South Africa (Dr Wegener)
| | - Ali H. Rafati
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark (Drs Ardalan and Wegener); Stereology and Electron Microscopy Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark (Drs Ardalan, Rafati, and Nyengaard); Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark (Drs Rafati and Nyengaard); Pharmaceutical Research Center of Excellence, School of Pharmacy (Pharmacology), North-West University, Potchefstroom, South Africa (Dr Wegener)
| | - Jens R. Nyengaard
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University Hospital, Risskov, Denmark (Drs Ardalan and Wegener); Stereology and Electron Microscopy Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark (Drs Ardalan, Rafati, and Nyengaard); Centre for Stochastic Geometry and Advanced Bioimaging, Aarhus University, Aarhus, Denmark (Drs Rafati and Nyengaard); Pharmaceutical Research Center of Excellence, School of Pharmacy (Pharmacology), North-West University, Potchefstroom, South Africa (Dr Wegener)
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33
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Bosch C, Muhaisen A, Pujadas L, Soriano E, Martínez A. Reelin Exerts Structural, Biochemical and Transcriptional Regulation Over Presynaptic and Postsynaptic Elements in the Adult Hippocampus. Front Cell Neurosci 2016; 10:138. [PMID: 27303269 PMCID: PMC4884741 DOI: 10.3389/fncel.2016.00138] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/10/2016] [Indexed: 11/13/2022] Open
Abstract
Reelin regulates neuronal positioning and synaptogenesis in the developing brain, and adult brain plasticity. Here we used transgenic mice overexpressing Reelin (Reelin-OE mice) to perform a comprehensive dissection of the effects of this protein on the structural and biochemical features of dendritic spines and axon terminals in the adult hippocampus. Electron microscopy (EM) revealed both higher density of synapses and structural complexity of both pre- and postsynaptic elements in transgenic mice than in WT mice. Dendritic spines had larger spine apparatuses, which correlated with a redistribution of Synaptopodin. Most of the changes observed in Reelin-OE mice were reversible after blockade of transgene expression, thus supporting the specificity of the observed phenotypes. Western blot and transcriptional analyses did not show major changes in the expression of pre- or postsynaptic proteins, including SNARE proteins, glutamate receptors, and scaffolding and signaling proteins. However, EM immunogold assays revealed that the NMDA receptor subunits NR2a and NR2b, and p-Cofilin showed a redistribution from synaptic to extrasynaptic pools. Taken together with previous studies, the present results suggest that Reelin regulates the structural and biochemical properties of adult hippocampal synapses by increasing their density and morphological complexity and by modifying the distribution and trafficking of major glutamatergic components.
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Affiliation(s)
- Carles Bosch
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of BarcelonaBarcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), MadridSpain; Vall d'Hebron Institut de RecercaBarcelona, Spain
| | - Ashraf Muhaisen
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of BarcelonaBarcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), MadridSpain; Vall d'Hebron Institut de RecercaBarcelona, Spain; Institute of Neurosciences, University of BarcelonaBarcelona, Spain
| | - Lluís Pujadas
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of BarcelonaBarcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), MadridSpain; Vall d'Hebron Institut de RecercaBarcelona, Spain
| | - Eduardo Soriano
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of BarcelonaBarcelona, Spain; Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), MadridSpain; Vall d'Hebron Institut de RecercaBarcelona, Spain; Institute of Neurosciences, University of BarcelonaBarcelona, Spain; Institució Catalana de Recerca i Estudis Avançats AcademiaBarcelona, Spain
| | - Albert Martínez
- Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona Barcelona, Spain
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Abstract
Fear memory is the best-studied form of memory. It was thoroughly investigated in the past 60 years mostly using two classical conditioning procedures (contextual fear conditioning and fear conditioning to a tone) and one instrumental procedure (one-trial inhibitory avoidance). Fear memory is formed in the hippocampus (contextual conditioning and inhibitory avoidance), in the basolateral amygdala (inhibitory avoidance), and in the lateral amygdala (conditioning to a tone). The circuitry involves, in addition, the pre- and infralimbic ventromedial prefrontal cortex, the central amygdala subnuclei, and the dentate gyrus. Fear learning models, notably inhibitory avoidance, have also been very useful for the analysis of the biochemical mechanisms of memory consolidation as a whole. These studies have capitalized on in vitro observations on long-term potentiation and other kinds of plasticity. The effect of a very large number of drugs on fear learning has been intensively studied, often as a prelude to the investigation of effects on anxiety. The extinction of fear learning involves to an extent a reversal of the flow of information in the mentioned structures and is used in the therapy of posttraumatic stress disorder and fear memories in general.
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Affiliation(s)
- Ivan Izquierdo
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Cristiane R. G. Furini
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Jociane C. Myskiw
- National Institute of Translational Neuroscience, National Research Council of Brazil, and Memory Center, Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Effect of Associative Learning on Memory Spine Formation in Mouse Barrel Cortex. Neural Plast 2015; 2016:9828517. [PMID: 26819780 PMCID: PMC4706958 DOI: 10.1155/2016/9828517] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/31/2015] [Accepted: 09/14/2015] [Indexed: 12/05/2022] Open
Abstract
Associative fear learning, in which stimulation of whiskers is paired with mild electric shock to the tail, modifies the barrel cortex, the functional representation of sensory receptors involved in the conditioning, by inducing formation of new inhibitory synapses on single-synapse spines of the cognate barrel hollows and thus producing double-synapse spines. In the barrel cortex of conditioned, pseudoconditioned, and untreated mice, we analyzed the number and morphological features of dendritic spines at various maturation and stability levels: sER-free spines, spines containing smooth endoplasmic reticulum (sER), and spines containing spine apparatus. Using stereological analysis of serial sections examined by transmission electron microscopy, we found that the density of double-synapse spines containing spine apparatus was significantly increased in the conditioned mice. Learning also induced enhancement of the postsynaptic density area of inhibitory synapses as well as increase in the number of polyribosomes in such spines. In single-synapse spines, the effects of conditioning were less pronounced and included increase in the number of polyribosomes in sER-free spines. The results suggest that fear learning differentially affects single- and double-synapse spines in the barrel cortex: it promotes maturation and stabilization of double-synapse spines, which might possibly contribute to permanent memory formation, and upregulates protein synthesis in single-synapse spines.
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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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Structural Components of Synaptic Plasticity and Memory Consolidation. Cold Spring Harb Perspect Biol 2015; 7:a021758. [PMID: 26134321 DOI: 10.1101/cshperspect.a021758] [Citation(s) in RCA: 243] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Consolidation of implicit memory in the invertebrate Aplysia and explicit memory in the mammalian hippocampus are associated with remodeling and growth of preexisting synapses and the formation of new synapses. Here, we compare and contrast structural components of the synaptic plasticity that underlies these two distinct forms of memory. In both cases, the structural changes involve time-dependent processes. Thus, some modifications are transient and may contribute to early formative stages of long-term memory, whereas others are more stable, longer lasting, and likely to confer persistence to memory storage. In addition, we explore the possibility that trans-synaptic signaling mechanisms governing de novo synapse formation during development can be reused in the adult for the purposes of structural synaptic plasticity and memory storage. Finally, we discuss how these mechanisms set in motion structural rearrangements that prepare a synapse to strengthen the same memory and, perhaps, to allow it to take part in other memories as a basis for understanding how their anatomical representation results in the enhanced expression and storage of memories in the brain.
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Blanque A, Repetto D, Rohlmann A, Brockhaus J, Duning K, Pavenstädt H, Wolff I, Missler M. Deletion of KIBRA, protein expressed in kidney and brain, increases filopodial-like long dendritic spines in neocortical and hippocampal neurons in vivo and in vitro. Front Neuroanat 2015; 9:13. [PMID: 25750616 PMCID: PMC4335192 DOI: 10.3389/fnana.2015.00013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 01/31/2015] [Indexed: 11/28/2022] Open
Abstract
Spines are small protrusions arising from dendrites that receive most excitatory synaptic input in the brain. Dendritic spines represent dynamic structures that undergo activity-dependent adaptations, for example, during synaptic plasticity. Alterations of spine morphology, changes of spine type ratios or density have consequently been found in paradigms of learning and memory, and accompany many neuropsychiatric disorders. Polymorphisms in the gene encoding KIBRA, a protein present in kidney and brain, are linked to memory performance and cognition in humans and mouse models. Deletion of KIBRA impairs long-term synaptic plasticity and postsynaptic receptor recycling but no information is available on the morphology of dendritic spines in null-mutant mice. Here, we directly examine the role of KIBRA in spinous synapses using knockout mice. Since KIBRA is normally highly expressed in neocortex and hippocampus at juvenile age, we analyze synapse morphology in intact tissue and in neuronal cultures from these brain regions. Quantification of different dendritic spine types in Golgi-impregnated sections and in transfected neurons coherently reveal a robust increase of filopodial-like long protrusions in the absence of KIBRA. While distribution of pre- and postsynaptic marker proteins, overall synapse ultrastructure and density of asymmetric contacts were remarkably normal, electron microscopy additionally uncovered less perforated synapses and spinules in knockout neurons. Thus, our results indicate that KIBRA is involved in the maintenance of normal ratios of spinous synapses, and may thus provide a structural correlate of altered cognitive functions when this memory-associated molecule is mutated.
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Affiliation(s)
- Anja Blanque
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany
| | - Daniele Repetto
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany
| | - Astrid Rohlmann
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany
| | - Johannes Brockhaus
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany
| | - Kerstin Duning
- Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Münster Münster, Germany
| | - Hermann Pavenstädt
- Internal Medicine D, Department of Nephrology, Hypertension and Rheumatology, University Hospital Münster Münster, Germany
| | - Ilka Wolff
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University Münster, Germany ; Cluster of Excellence EXC 1003, Cells in Motion, CiM Münster, Germany
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Caroni P, Chowdhury A, Lahr M. Synapse rearrangements upon learning: from divergent-sparse connectivity to dedicated sub-circuits. Trends Neurosci 2014; 37:604-14. [PMID: 25257207 DOI: 10.1016/j.tins.2014.08.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 08/26/2014] [Accepted: 08/27/2014] [Indexed: 01/24/2023]
Abstract
Learning can involve formation of new synapses and loss of synapses, providing memory traces of learned skills. Recent findings suggest that these synapse rearrangements reflect assembly of task-related sub-circuits from initially broadly distributed and sparse connectivity in the brain. These local circuit remodeling processes involve rapid emergence of synapses upon learning, followed by protracted validation involving strengthening of some new synapses, and selective elimination of others. The timing of these consolidation processes can vary. Here, we review these findings, focusing on how molecular/cellular mechanisms of synapse assembly, strengthening, and elimination might interface with circuit/system mechanisms of learning and memory consolidation. An integrated understanding of these learning-related processes should provide a better basis to elucidate how experience, genetic background, and disease influence brain function.
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Affiliation(s)
- Pico Caroni
- Friedrich Miescher Institut, Basel, Switzerland.
| | | | - Maria Lahr
- Friedrich Miescher Institut, Basel, Switzerland
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Impaired hippocampal neuroligin-2 function by chronic stress or synthetic peptide treatment is linked to social deficits and increased aggression. Neuropsychopharmacology 2014; 39:1148-58. [PMID: 24213355 PMCID: PMC3957108 DOI: 10.1038/npp.2013.315] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 09/20/2013] [Accepted: 10/31/2013] [Indexed: 11/08/2022]
Abstract
Neuroligins (NLGNs) are cell adhesion molecules that are important for proper synaptic formation and functioning, and are critical regulators of the balance between neural excitation/inhibition (E/I). Mutations in NLGNs have been linked to psychiatric disorders in humans involving social dysfunction and are related to similar abnormalities in animal models. Chronic stress increases the likelihood for affective disorders and has been shown to induce changes in neural structure and function in different brain regions, with the hippocampus being highly vulnerable to stress. Previous studies have shown evidence of chronic stress-induced changes in the neural E/I balance in the hippocampus. Therefore, we hypothesized that chronic restraint stress would lead to reduced hippocampal NLGN-2 levels, in association with alterations in social behavior. We found that rats submitted to chronic restraint stress in adulthood display reduced sociability and increased aggression. This occurs along with a reduction of NLGN-2, but not NLGN-1 expression (as shown with western blot, immunohistochemistry, and electron microscopy analyses), throughout the hippocampus and detectable in different layers of the CA1, CA3, and DG subfields. Furthermore, using synthetic peptides that comprise sequences in either NLGN-1 (neurolide-1) or NLGN-2 (neurolide-2) involved in the interaction with their presynaptic partner neurexin (NRXN)-1, intra-hippocampal administration of neurolide-2 led also to reduced sociability and increased aggression. These results highlight hippocampal NLGN-2 as a key molecular substrate regulating social behaviors and underscore NLGNs as promising targets for the development of novel drugs for the treatment of dysfunctional social behaviors.
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Petralia RS, Mattson MP, Yao PJ. Communication breakdown: the impact of ageing on synapse structure. Ageing Res Rev 2014; 14:31-42. [PMID: 24495392 PMCID: PMC4094371 DOI: 10.1016/j.arr.2014.01.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 12/16/2013] [Accepted: 01/23/2014] [Indexed: 01/13/2023]
Abstract
Impaired synaptic plasticity is implicated in the functional decline of the nervous system associated with ageing. Understanding the structure of ageing synapses is essential to understanding the functions of these synapses and their role in the ageing nervous system. In this review, we summarize studies on ageing synapses in vertebrates and invertebrates, focusing on changes in morphology and ultrastructure. We cover different parts of the nervous system, including the brain, the retina, the cochlea, and the neuromuscular junction. The morphological characteristics of aged synapses could shed light on the underlying molecular changes and their functional consequences.
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Affiliation(s)
- Ronald S Petralia
- Advanced Imaging Core, NIDCD/NIH, Bethesda, MD 20892, United States.
| | - Mark P Mattson
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, United States
| | - Pamela J Yao
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, MD 21224, United States.
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Sala C, Segal M. Dendritic spines: the locus of structural and functional plasticity. Physiol Rev 2014; 94:141-88. [PMID: 24382885 DOI: 10.1152/physrev.00012.2013] [Citation(s) in RCA: 338] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The introduction of high-resolution time lapse imaging and molecular biological tools has changed dramatically the rate of progress towards the understanding of the complex structure-function relations in synapses of central spiny neurons. Standing issues, including the sequence of molecular and structural processes leading to formation, morphological change, and longevity of dendritic spines, as well as the functions of dendritic spines in neurological/psychiatric diseases are being addressed in a growing number of recent studies. There are still unsettled issues with respect to spine formation and plasticity: Are spines formed first, followed by synapse formation, or are synapses formed first, followed by emergence of a spine? What are the immediate and long-lasting changes in spine properties following exposure to plasticity-producing stimulation? Is spine volume/shape indicative of its function? These and other issues are addressed in this review, which highlights the complexity of molecular pathways involved in regulation of spine structure and function, and which contributes to the understanding of central synaptic interactions in health and disease.
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Kawahara A, Kurauchi S, Fukata Y, Martínez-Hernández J, Yagihashi T, Itadani Y, Sho R, Kajiyama T, Shinzato N, Narusuye K, Fukata M, Luján R, Shigemoto R, Ito I. Neuronal major histocompatibility complex class I molecules are implicated in the generation of asymmetries in hippocampal circuitry. J Physiol 2013; 591:4777-91. [PMID: 23878366 DOI: 10.1113/jphysiol.2013.252122] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Left-right asymmetry is a fundamental feature of higher-order brain function; however, the molecular basis of brain asymmetry has remained unclear. We have recently demonstrated asymmetries in hippocampal circuitry resulting from the asymmetrical allocation of NMDA receptor (NMDAR) subunit GluR2 (NR2B) in pyramidal cell synapses. This asymmetrical allocation of 2 subunits affects the properties of NMDARs and generates two populations of synapses, '2-dominant' and '2-non-dominant' synapses, according to the hemispheric origin of presynaptic inputs and cell polarity of the postsynaptic neurone. To identify key regulators for generating asymmetries, we analysed the hippocampus of β2-microglobulin (β2m)-deficient mice lacking cell surface expression of major histocompatibility complex class I (MHCI). Although MHCI proteins are well known in the immune system, accumulating evidence indicates that MHCI proteins are expressed in the brain and are required for activity-dependent refinement of neuronal connections and normal synaptic plasticity. We found that β2m proteins were localised in hippocampal synapses in wild-type mice. NMDA EPSCs in β2m-deficient hippocampal synapses receiving inputs from both hemispheres showed similar sensitivity to Ro 25-6981, an 2 subunit-selective antagonist, with those in '2-dominant' synapses for both the apical and basal synapses of pyramidal neurones. The structural features of the β2m-deficient synapse in addition to the relationship between the stimulation frequency and synaptic plasticity were also comparable to those of '2-dominant' synapses. These observations indicate that the β2m-deficient hippocampus lacks '2-non-dominant' synapses and circuit asymmetries. Our findings provide evidence supporting a critical role of MHCI molecules for generating asymmetries in hippocampal circuitry.
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Affiliation(s)
- Aiko Kawahara
- I. Ito: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
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The synaptic maintenance problem: membrane recycling, Ca2+ homeostasis and late onset degeneration. Mol Neurodegener 2013; 8:23. [PMID: 23829673 PMCID: PMC3708831 DOI: 10.1186/1750-1326-8-23] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/05/2013] [Indexed: 01/02/2023] Open
Abstract
Most neurons are born with the potential to live for the entire lifespan of the organism. In addition, neurons are highly polarized cells with often long axons, extensively branched dendritic trees and many synaptic contacts. Longevity together with morphological complexity results in a formidable challenge to maintain synapses healthy and functional. This challenge is often evoked to explain adult-onset degeneration in numerous neurodegenerative disorders that result from otherwise divergent causes. However, comparably little is known about the basic cell biological mechanisms that keep normal synapses alive and functional in the first place. How the basic maintenance mechanisms are related to slow adult-onset degeneration in different diseasesis largely unclear. In this review we focus on two basic and interconnected cell biological mechanisms that are required for synaptic maintenance: endomembrane recycling and calcium (Ca2+) homeostasis. We propose that subtle defects in these homeostatic processes can lead to late onset synaptic degeneration. Moreover, the same basic mechanisms are hijacked, impaired or overstimulated in numerous neurodegenerative disorders. Understanding the pathogenesis of these disorders requires an understanding of both the initial cause of the disease and the on-going changes in basic maintenance mechanisms. Here we discuss the mechanisms that keep synapses functional over long periods of time with the emphasis on their role in slow adult-onset neurodegeneration.
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Age-Induced Loss of Mossy Fibre Synapses on CA3 Thorns in the CA3 Stratum Lucidum. NEUROSCIENCE JOURNAL 2013; 2013:839535. [PMID: 26317100 PMCID: PMC4437271 DOI: 10.1155/2013/839535] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/19/2013] [Indexed: 01/08/2023]
Abstract
Advanced ageing is associated with hippocampal deterioration and mild cognitive decline. The hippocampal subregion CA3 stratum lucidum (CA3-SL) receives neuronal inputs from the giant mossy fibre boutons of the dentate gyrus, but relatively little is known about the integrity of this synaptic connection with ageing. Using serial electron microscopy and unbiased stereology, we examined age-related changes in mossy fibre synapses on CA3 thorny excrescences within the CA3-SL of young adults (4-month-old), middle-aged (12-month-old), and old-aged (28-month-old) Wistar rats. Our data show that while there is an increase in CA3 volume with ageing, there is a significant (40–45%) reduction in synaptic density within the CA3-SL of 12- and 28-month-old animals compared with 4-month-old animals. We also present preliminary data showing that the CA3 neuropil in advanced ageing was conspicuously full of lipofuscin and phagolysosome positive, activated microglial cellular processes, and altered perivascular pathology. These data suggest that synaptic density in the CA3-SL is significantly impaired in ageing, accompanied by underlying prominent ultrastructural glial and microvascular changes.
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Shirmanova MV, Serebrovskaya EO, Lukyanov KA, Snopova LB, Sirotkina MA, Prodanetz NN, Bugrova ML, Minakova EA, Turchin IV, Kamensky VA, Lukyanov SA, Zagaynova EV. Phototoxic effects of fluorescent protein KillerRed on tumor cells in mice. JOURNAL OF BIOPHOTONICS 2013; 6:283-90. [PMID: 22696211 DOI: 10.1002/jbio.201200056] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/12/2012] [Accepted: 05/21/2012] [Indexed: 06/01/2023]
Abstract
KillerRed is known to be a unique red fluorescent protein displaying strong phototoxic properties. Its effectiveness has been shown previously for killing bacterial and cancer cells in vitro. Here, we investigated the photototoxicity of the protein on tumor xenografts in mice. HeLa Kyoto cell line stably expressing KillerRed in mitochondria and in fusion with histone H2B was used. Irradiation of the tumors with 593 nm laser led to photobleaching of KillerRed indicating photosensitization reaction and caused significant destruction of the cells and activation of apoptosis. The portion of the dystrophically changed cells increased from 9.9% to 63.7%, and the cells with apoptosis hallmarks from 6.3% to 14%. The results of this study suggest KillerRed as a potential genetically encoded photosensitizer for photodynamic therapy of cancer.
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Affiliation(s)
- Marina V Shirmanova
- Nizhny Novgorod State Medical Academy, 603005 Minin Sq., 10/1, Nizhny Novgorod, Russia.
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Multiple spine boutons are formed after long-lasting LTP in the awake rat. Brain Struct Funct 2012; 219:407-14. [PMID: 23224218 DOI: 10.1007/s00429-012-0488-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 11/16/2012] [Indexed: 01/25/2023]
Abstract
The formation of multiple spine boutons (MSBs) has been associated with cognitive abilities including hippocampal-dependent associative learning and memory. Data obtained from cultured hippocampal slices suggest that the long-term maintenance of synaptic plasticity requires the formation of new synaptic contacts on pre-existing synapses. This postulate however, has never been tested in the awake, freely moving animals. In the current study, we induced long-term potentiation (LTP) in the dentate gyrus (DG) of awake adult rats and performed 3-D reconstructions of electron micrographs from thin sections of both axonal boutons and dendritic spines, 24 h post-induction. The specificity of the observed changes was demonstrated by comparison with animals in which long-term depression (LTD) had been induced, or with animals in which LTP was blocked by an N-methyl-D-aspartate (NMDA) antagonist. Our data demonstrate that whilst the number of boutons remains unchanged, there is a marked increase in the number of synapses per bouton 24 h after the induction of LTP. Further, we demonstrate that this increase is specific to mushroom spines and not attributable to their division. The present investigation thus fills the gap existing between behavioural and in vitro studies on the role of MSB formation in synaptic plasticity and cognitive abilities.
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Ojo B, Gabbott PL, Rezaie P, Corbett N, Medvedev NI, Cowley TR, Lynch MA, Stewart MG. An NCAM mimetic, FGL, alters hippocampal cellular morphometry in young adult (4 month-old) rats. Neurochem Res 2012; 38:1208-18. [PMID: 23076631 DOI: 10.1007/s11064-012-0908-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/16/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022]
Abstract
The neural cell adhesion molecule, NCAM, is ubiquitously expressed within the CNS and has roles in development, cognition, neural plasticity and regulation of the immune system. NCAM is thus potentially an important pharmacological target for treatment of brain diseases. A cell adhesion mimetic FGL, a 15 amino-acid peptide derived from the second fibronectin type-III module of NCAM, has been shown to act as a neuroprotective agent in experimental disease and ageing models, restoring hippocampal/cognitive function and markedly alleviating deleterious changes in the CNS. However, the effects of FGL on the hippocampus of young healthy rats are unknown. The present study has examined the cellular neurobiological consequences of subcutaneous injections of FGL, on hippocampal cell morphometry in young (4 month-old) rats. We determined the effects of FGL on hippocampal volume, pyramidal neuron number/density (using unbiased quantitative stereology), and examined aspects of neurogenesis (using 2D morphometric analyses). FGL treatment reduced total volume of the dorsal hippocampus (associated with a decrease in total pyramidal neuron numbers in CA1 and CA3), and elevated the number of doublecortin immunolabeled neurons in the dentate gyrus, indicating a likely influence on neurogenesis in young healthy rats. These data indicate that FGL has a specific age dependent effect on the hippocampus, differing according to the development and maturity of the CNS.
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Affiliation(s)
- Bunmi Ojo
- Department of Life, Health and Chemical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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Ohkawa N, Saitoh Y, Tokunaga E, Nihonmatsu I, Ozawa F, Murayama A, Shibata F, Kitamura T, Inokuchi K. Spine formation pattern of adult-born neurons is differentially modulated by the induction timing and location of hippocampal plasticity. PLoS One 2012; 7:e45270. [PMID: 23024813 PMCID: PMC3443223 DOI: 10.1371/journal.pone.0045270] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/14/2012] [Indexed: 12/13/2022] Open
Abstract
In the adult hippocampus dentate gyrus (DG), newly born neurons are functionally integrated into existing circuits and play important roles in hippocampus-dependent memory. However, it remains unclear how neural plasticity regulates the integration pattern of new neurons into preexisting circuits. Because dendritic spines are major postsynaptic sites for excitatory inputs, spines of new neurons were visualized by retrovirus-mediated labeling to evaluate integration. Long-term potentiation (LTP) was induced at 12, 16, or 21 days postinfection (dpi), at which time new neurons have no, few, or many spines, respectively. The spine expression patterns were investigated at one or two weeks after LTP induction. Induction at 12 dpi increased later spinogenesis, although the new neurons at 12 dpi didn't respond to the stimulus for LTP induction. Induction at 21 dpi transiently mediated spine enlargement. Surprisingly, LTP induction at 16 dpi reduced the spine density of new neurons. All LTP-mediated changes specifically appeared within the LTP-induced layer. Therefore, neural plasticity differentially regulates the integration of new neurons into the activated circuit, dependent on their developmental stage. Consequently, new neurons at different developmental stages may play distinct roles in processing the acquired information by modulating the connectivity of activated circuits via their integration.
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Affiliation(s)
- Noriaki Ohkawa
- Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Yoshito Saitoh
- Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Eri Tokunaga
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Itsuko Nihonmatsu
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Fumiko Ozawa
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Akiko Murayama
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
| | - Fumi Shibata
- Division of Cellular Therapy, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Toshio Kitamura
- Division of Cellular Therapy, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Kaoru Inokuchi
- Department of Biochemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, Toyama, Japan
- JST, CREST, Kawaguchi, Japan
- Mitsubishi Kagaku Institute of Life Sciences, MITILS, Machida, Tokyo, Japan
- * E-mail:
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Majumder P, Chen YT, Bose JK, Wu CC, Cheng WC, Cheng SJ, Fang YH, Chen YL, Tsai KJ, Lien CC, Shen CKJ. TDP-43 regulates the mammalian spinogenesis through translational repression of Rac1. Acta Neuropathol 2012; 124:231-45. [PMID: 22760527 DOI: 10.1007/s00401-012-1006-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 06/18/2012] [Accepted: 06/19/2012] [Indexed: 12/13/2022]
Abstract
Impairment of learning and memory is a significant pathological feature of many neurodegenerative diseases including FTLD-TDP. Appropriate regulation and fine tuning of spinogenesis of the dendrites, which is an integral part of the learning/memory program of the mammalian brain, are essential for the normal function of the hippocampal neurons. TDP-43 is a nucleic acid-binding protein implicated in multi-cellular functions and in the pathogenesis of a range of neurodegenerative diseases including FTLD-TDP and ALS. We have combined the use of single-cell dye injection, shRNA knockdown, plasmid rescue, immunofluorescence staining, Western blot analysis and patch clamp electrophysiological measurement of primary mouse hippocampal neurons in culture to study the functional role of TDP-43 in mammalian spinogenesis. We found that depletion of TDP-43 leads to an increase in the number of protrusions/spines as well as the percentage of matured spines among the protrusions. Significantly, the knockdown of TDP-43 also increases the level of Rac1 and its activated form GTP-Rac1, a known positive regulator of spinogenesis. Clustering of the AMPA receptors on the dendritic surface and neuronal firing are also induced by depletion of TDP-43. Furthermore, use of an inhibitor of Rac1 activation negatively regulated spinogenesis of control hippocampal neurons as well as TDP-43-depleted hippocampal neurons. Mechanistically, RT-PCR assay and cycloheximide chase experiments have indicated that increases in Rac1 protein upon TDP-43 depletion is regulated at the translational level. These data together establish that TDP-43 is an upstream regulator of spinogenesis in part through its action on the Rac1 → GTP-Rac1 → AMPAR pathway. This study provides the first evidence connecting TDP-43 with the GTP-Rac1 → AMPAR regulatory pathway of spinogenesis. It establishes that mis-metabolism of TDP-43, as occurs in neurodegenerative diseases with TDP-43 proteinopathies, e.g., FTLD-TDP, would alter its homeostatic cellular concentration, thus leading to impairment of hippocampal plasticity.
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Affiliation(s)
- Pritha Majumder
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, 115, Taiwan
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