1
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Thomas CI, Ryan MA, McNabb MC, Kamasawa N, Scholl B. Astrocyte coverage of excitatory synapses correlates to measures of synapse structure and function in ferret primary visual cortex. Glia 2024. [PMID: 38856149 DOI: 10.1002/glia.24582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 05/25/2024] [Accepted: 06/02/2024] [Indexed: 06/11/2024]
Abstract
Most excitatory synapses in the mammalian brain are contacted or ensheathed by astrocyte processes, forming tripartite synapses. Astrocytes are thought to be critical regulators of the structural and functional dynamics of synapses. While the degree of synaptic coverage by astrocytes is known to vary across brain regions and animal species, the reason for and implications of this variability remains unknown. Further, how astrocyte coverage of synapses relates to in vivo functional properties of individual synapses has not been investigated. Here, we characterized astrocyte coverage of synapses of pyramidal neurons in the ferret visual cortex and, using correlative light and electron microscopy, examined their relationship to synaptic strength and sensory-evoked Ca2+ activity. Nearly, all synapses were contacted by astrocytes, and most were contacted along the axon-spine interface. Structurally, we found that the degree of synaptic astrocyte coverage directly scaled with synapse size and postsynaptic density complexity. Functionally, we found that the amount of astrocyte coverage scaled with how selectively a synapse responds to a particular visual stimulus and, at least for the largest synapses, scaled with the reliability of visual stimuli to evoke postsynaptic Ca2+ events. Our study shows astrocyte coverage is highly correlated with structural metrics of synaptic strength of excitatory synapses in the visual cortex and demonstrates a previously unknown relationship between astrocyte coverage and reliable sensory activation.
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Affiliation(s)
- Connon I Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Melissa A Ryan
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Micaiah C McNabb
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, Florida, USA
| | - Benjamin Scholl
- Department of Physiology and Biophysics, University of Colorado Denver, Aurora, Colorado, USA
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2
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Gau YTA, Hsu ET, Cha RJ, Pak RW, Looger LL, Kang JU, Bergles DE. Multicore fiber optic imaging reveals that astrocyte calcium activity in the mouse cerebral cortex is modulated by internal motivational state. Nat Commun 2024; 15:3039. [PMID: 38589390 PMCID: PMC11002016 DOI: 10.1038/s41467-024-47345-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 03/25/2024] [Indexed: 04/10/2024] Open
Abstract
Astrocytes are a direct target of neuromodulators and can influence neuronal activity on broad spatial and temporal scales in response to a rise in cytosolic calcium. However, our knowledge about how astrocytes are recruited during different animal behaviors remains limited. To measure astrocyte activity calcium in vivo during normative behaviors, we utilize a high-resolution, long working distance multicore fiber optic imaging system that allows visualization of individual astrocyte calcium transients in the cerebral cortex of freely moving mice. We define the spatiotemporal dynamics of astrocyte calcium changes during diverse behaviors, ranging from sleep-wake cycles to the exploration of novel objects, showing that their activity is more variable and less synchronous than apparent in head-immobilized imaging conditions. In accordance with their molecular diversity, individual astrocytes often exhibit distinct thresholds and activity patterns during explorative behaviors, allowing temporal encoding across the astrocyte network. Astrocyte calcium events were induced by noradrenergic and cholinergic systems and modulated by internal state. The distinct activity patterns exhibited by astrocytes provides a means to vary their neuromodulatory influence in different behavioral contexts and internal states.
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Affiliation(s)
- Yung-Tian A Gau
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
| | - Eric T Hsu
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA
| | - Richard J Cha
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Rebecca W Pak
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Loren L Looger
- Howard Hughes Medical Institute, Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Jin U Kang
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Dwight E Bergles
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, USA.
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3
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Lu B, Qiu X, Yang W, Yao Z, Ma X, Deng S, Zhang Q, Fu J, Qi Y. Genetic Basis and Evolutionary Forces of Sexually Dimorphic Color Variation in a Toad-Headed Agamid Lizard. Mol Biol Evol 2024; 41:msae054. [PMID: 38466135 PMCID: PMC10963123 DOI: 10.1093/molbev/msae054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 02/17/2024] [Accepted: 03/04/2024] [Indexed: 03/12/2024] Open
Abstract
In the animal kingdom, sexually dimorphic color variation is a widespread phenomenon that significantly influences survival and reproductive success. However, the genetic underpinnings of this variation remain inadequately understood. Our investigation into sexually dimorphic color variation in the desert-dwelling Guinan population of the toad-headed agamid lizard (Phrynocephalus putjatai) utilized a multidisciplinary approach, encompassing phenotypic, ultrastructural, biochemical, genomic analyses, and behavioral experiments. Our findings unveil the association between distinct skin colorations and varying levels of carotenoid and pteridine pigments. The red coloration in males is determined by a genomic region on chromosome 14, housing four pigmentation genes: BCO2 and three 6-pyruvoyltetrahydropterin synthases. A Guinan population-specific nonsynonymous single nucleotide polymorphism in BCO2 is predicted to alter the electrostatic potential within the binding domain of the BCO2-β-carotene complex, influencing their interaction. Additionally, the gene MAP7 on chromosome 2 emerges as a potential contributor to the blue coloration in subadults and adult females. Sex-specific expression patterns point to steroid hormone-associated genes (SULT2B1 and SRD5A2) as potential upstream regulators influencing sexually dimorphic coloration. Visual modeling and field experiments support the potential selective advantages of vibrant coloration in desert environments. This implies that natural selection, potentially coupled with assortative mating, might have played a role in fixing color alleles, contributing to prevalence in the local desert habitat. This study provides novel insights into the genetic basis of carotenoid and pteridine-based color variation, shedding light on the evolution of sexually dimorphic coloration in animals. Moreover, it advances our understanding of the driving forces behind such intricate coloration patterns.
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Affiliation(s)
- Bin Lu
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Xia Qiu
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
- College of Life Sciences, China Jiliang University, Hangzhou, China
| | - Weizhao Yang
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Zhongyi Yao
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Xiaofeng Ma
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Shunyan Deng
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Qi Zhang
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
| | - Jinzhong Fu
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G2W1, Canada
| | - Yin Qi
- Chengdu Institute of Biology, Chinese Academy of Sciences, 610041 Chengdu, Sichuan, China
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Thomas CI, Ryan MA, McNabb MC, Kamasawa N, Scholl B. Astrocyte coverage of excitatory synapses correlates to measures of synapse structure and function in primary visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.01.569664. [PMID: 38106030 PMCID: PMC10723302 DOI: 10.1101/2023.12.01.569664] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Most excitatory synapses in the mammalian brain are contacted by astrocytes, forming the tripartite synapse. This interface is thought to be critical for glutamate turnover and structural or functional dynamics of synapses. While the degree of synaptic contact of astrocytes is known to vary across brain regions and animal species, the implications of this variability remain unknown. Furthermore, precisely how astrocyte coverage of synapses relates to in vivo functional properties of individual dendritic spines has yet to be investigated. Here, we characterized perisynaptic astrocyte processes (PAPs) contacting synapses of pyramidal neurons of the ferret visual cortex and, using correlative light and electron microscopy, examined their relationship to synaptic strength and to sensory-evoked Ca2+ activity. Nearly all synapses were contacted by PAPs, and most were contacted along the axon-spine interface (ASI). Structurally, we found that the degree of PAP coverage scaled with synapse size and complexity. Functionally, we found that PAP coverage scaled with the selectivity of Ca2+ responses of individual synapses to visual stimuli and, at least for the largest synapses, scaled with the reliability of visual stimuli to evoke postsynaptic Ca2+ events. Our study shows astrocyte coverage is highly correlated with structural properties of excitatory synapses in the visual cortex and implicates astrocytes as a contributor to reliable sensory activation.
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Affiliation(s)
- Connon I Thomas
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Melissa A Ryan
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
- Department of Neuroscience, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
| | - Micaiah C McNabb
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
- Department of Neuroscience, The Ohio State University, 460 Medical Center Drive, Columbus, OH 43210, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Benjamin Scholl
- Department of Physiology and Biophysics, University of Colorado Denver, 12800 East 19th Ave, Aurora, CO 80045, USA
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Yao ZM, Sun XR, Huang J, Chen L, Dong SY. Astrocyte-Neuronal Communication and Its Role in Stroke. Neurochem Res 2023; 48:2996-3006. [PMID: 37329448 DOI: 10.1007/s11064-023-03966-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/03/2023] [Accepted: 06/06/2023] [Indexed: 06/19/2023]
Abstract
Astrocytes are the most abundant glial cells in the central nervous system. These cells are an important hub for intercellular communication. They participate in various pathophysiological processes, including synaptogenesis, metabolic transformation, scar production, and blood-brain barrier repair. The mechanisms and functional consequences of astrocyte-neuron signaling are more complex than previously thought. Stroke is a disease associated with neurons in which astrocytes also play an important role. Astrocytes respond to the alterations in the brain microenvironment after stroke, providing required substances to neurons. However, they can also have harmful effects. In this review, we have summarized the function of astrocytes, their association with neurons, and two paradigms of the inflammatory response, which suggest that targeting astrocytes may be an effective strategy for treating stroke.
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Affiliation(s)
- Zi-Meng Yao
- Department of Pharmacology, School of Pharmacy, Bengbu Medical College, Bengbu, Anhui, China
| | - Xiao-Rong Sun
- Department of Pharmacology, School of Pharmacy, Bengbu Medical College, Bengbu, Anhui, China
| | - Jie Huang
- Department of Pharmacology, School of Pharmacy, Bengbu Medical College, Bengbu, Anhui, China
| | - Lei Chen
- Department of Pharmacology, School of Pharmacy, Bengbu Medical College, Bengbu, Anhui, China
| | - Shu-Ying Dong
- Department of Pharmacology, School of Pharmacy, Bengbu Medical College, Bengbu, Anhui, China.
- Bengbu Medical College Key Laboratory of Cardiovascular and Cerebrovascular Diseases, Bengbu, Anhui, China.
- Anhui Engineering Technology Research Center of Biochemical Pharmaceutical, Bengbu, Anhui, China.
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Hageter J, Starkey J, Horstick EJ. Thalamic regulation of a visual critical period and motor behavior. Cell Rep 2023; 42:112287. [PMID: 36952349 PMCID: PMC10514242 DOI: 10.1016/j.celrep.2023.112287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/02/2023] [Accepted: 03/03/2023] [Indexed: 03/24/2023] Open
Abstract
During the visual critical period (CP), sensory experience refines the structure and function of visual circuits. The basis of this plasticity was long thought to be limited to cortical circuits, but recently described thalamic plasticity challenges this dogma and demonstrates greater complexity underlying visual plasticity. Yet how visual experience modulates thalamic neurons or how the thalamus modulates CP timing is incompletely understood. Using a larval zebrafish, thalamus-centric ocular dominance model, we show functional changes in the thalamus and a role of inhibitory signaling to establish CP timing using a combination of functional imaging, optogenetics, and pharmacology. Hemisphere-specific changes in genetically defined thalamic neurons correlate with changes in visuomotor behavior, establishing a role of thalamic plasticity in modulating motor performance. Our work demonstrates that visual plasticity is broadly conserved and that visual experience leads to neuron-level functional changes in the thalamus that require inhibitory signaling to establish critical period timing.
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Affiliation(s)
- John Hageter
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA
| | - Jacob Starkey
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA
| | - Eric J Horstick
- Department of Biology, West Virginia University, Morgantown, WV 26506, USA; Department of Neuroscience, West Virginia University, Morgantown, WV 26506, USA.
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Ribeiro FM, Castelo-Branco M, Gonçalves J, Martins J. Visual Cortical Plasticity: Molecular Mechanisms as Revealed by Induction Paradigms in Rodents. Int J Mol Sci 2023; 24:ijms24054701. [PMID: 36902131 PMCID: PMC10003432 DOI: 10.3390/ijms24054701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/24/2023] [Accepted: 02/26/2023] [Indexed: 03/05/2023] Open
Abstract
Assessing the molecular mechanism of synaptic plasticity in the cortex is vital for identifying potential targets in conditions marked by defective plasticity. In plasticity research, the visual cortex represents a target model for intense investigation, partly due to the availability of different in vivo plasticity-induction protocols. Here, we review two major protocols: ocular-dominance (OD) and cross-modal (CM) plasticity in rodents, highlighting the molecular signaling pathways involved. Each plasticity paradigm has also revealed the contribution of different populations of inhibitory and excitatory neurons at different time points. Since defective synaptic plasticity is common to various neurodevelopmental disorders, the potentially disrupted molecular and circuit alterations are discussed. Finally, new plasticity paradigms are presented, based on recent evidence. Stimulus-selective response potentiation (SRP) is one of the paradigms addressed. These options may provide answers to unsolved neurodevelopmental questions and offer tools to repair plasticity defects.
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Affiliation(s)
- Francisco M. Ribeiro
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Miguel Castelo-Branco
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Joana Gonçalves
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
- Correspondence:
| | - João Martins
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, 3000-548 Coimbra, Portugal
- Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, 3000-548 Coimbra, Portugal
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8
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Rasia-Filho AA, Calcagnotto ME, von Bohlen Und Halbach O. Glial Cell Modulation of Dendritic Spine Structure and Synaptic Function. ADVANCES IN NEUROBIOLOGY 2023; 34:255-310. [PMID: 37962798 DOI: 10.1007/978-3-031-36159-3_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Glia comprise a heterogeneous group of cells involved in the structure and function of the central and peripheral nervous system. Glial cells are found from invertebrates to humans with morphological specializations related to the neural circuits in which they are embedded. Glial cells modulate neuronal functions, brain wiring and myelination, and information processing. For example, astrocytes send processes to the synaptic cleft, actively participate in the metabolism of neurotransmitters, and release gliotransmitters, whose multiple effects depend on the targeting cells. Human astrocytes are larger and more complex than their mice and rats counterparts. Astrocytes and microglia participate in the development and plasticity of neural circuits by modulating dendritic spines. Spines enhance neuronal connectivity, integrate most postsynaptic excitatory potentials, and balance the strength of each input. Not all central synapses are engulfed by astrocytic processes. When that relationship occurs, a different pattern for thin and large spines reflects an activity-dependent remodeling of motile astrocytic processes around presynaptic and postsynaptic elements. Microglia are equally relevant for synaptic processing, and both glial cells modulate the switch of neuroendocrine secretion and behavioral display needed for reproduction. In this chapter, we provide an overview of the structure, function, and plasticity of glial cells and relate them to synaptic maturation and modulation, also involving neurotrophic factors. Together, neurons and glia coordinate synaptic transmission in both normal and abnormal conditions. Neglected over decades, this exciting research field can unravel the complexity of species-specific neural cytoarchitecture as well as the dynamic region-specific functional interactions between diverse neurons and glial subtypes.
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Affiliation(s)
- Alberto A Rasia-Filho
- Department of Basic Sciences/Physiology and Graduate Program in Biosciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Maria Elisa Calcagnotto
- Graduate Program in Neuroscience, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Department of Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Graduate Program in Psychiatry and Behavioral Science, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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9
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Benfey N, Foubert D, Ruthazer ES. Glia Regulate the Development, Function, and Plasticity of the Visual System From Retina to Cortex. Front Neural Circuits 2022; 16:826664. [PMID: 35177968 PMCID: PMC8843846 DOI: 10.3389/fncir.2022.826664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/07/2022] [Indexed: 11/13/2022] Open
Abstract
Visual experience is mediated through a relay of finely-tuned neural circuits extending from the retina, to retinorecipient nuclei in the midbrain and thalamus, to the cortex which work together to translate light information entering our eyes into a complex and dynamic spatio-temporal representation of the world. While the experience-dependent developmental refinement and mature function of neurons in each major stage of the vertebrate visual system have been extensively characterized, the contributions of the glial cells populating each region are comparatively understudied despite important findings demonstrating that they mediate crucial processes related to the development, function, and plasticity of the system. In this article we review the mechanisms for neuron-glia communication throughout the vertebrate visual system, as well as functional roles attributed to astrocytes and microglia in visual system development and processing. We will also discuss important aspects of glial function that remain unclear, integrating the knowns and unknowns about glia in the visual system to advance new hypotheses to guide future experimental work.
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10
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Jenks KR, Tsimring K, Ip JPK, Zepeda JC, Sur M. Heterosynaptic Plasticity and the Experience-Dependent Refinement of Developing Neuronal Circuits. Front Neural Circuits 2021; 15:803401. [PMID: 34949992 PMCID: PMC8689143 DOI: 10.3389/fncir.2021.803401] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 01/01/2023] Open
Abstract
Neurons remodel the structure and strength of their synapses during critical periods of development in order to optimize both perception and cognition. Many of these developmental synaptic changes are thought to occur through synapse-specific homosynaptic forms of experience-dependent plasticity. However, homosynaptic plasticity can also induce or contribute to the plasticity of neighboring synapses through heterosynaptic interactions. Decades of research in vitro have uncovered many of the molecular mechanisms of heterosynaptic plasticity that mediate local compensation for homosynaptic plasticity, facilitation of further bouts of plasticity in nearby synapses, and cooperative induction of plasticity by neighboring synapses acting in concert. These discoveries greatly benefited from new tools and technologies that permitted single synapse imaging and manipulation of structure, function, and protein dynamics in living neurons. With the recent advent and application of similar tools for in vivo research, it is now feasible to explore how heterosynaptic plasticity contribute to critical periods and the development of neuronal circuits. In this review, we will first define the forms heterosynaptic plasticity can take and describe our current understanding of their molecular mechanisms. Then, we will outline how heterosynaptic plasticity may lead to meaningful refinement of neuronal responses and observations that suggest such mechanisms are indeed at work in vivo. Finally, we will use a well-studied model of cortical plasticity—ocular dominance plasticity during a critical period of visual cortex development—to highlight the molecular overlap between heterosynaptic and developmental forms of plasticity, and suggest potential avenues of future research.
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Affiliation(s)
- Kyle R Jenks
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Katya Tsimring
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Jacque Pak Kan Ip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Jose C Zepeda
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Mriganka Sur
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
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11
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Staurenghi E, Giannelli S, Testa G, Sottero B, Leonarduzzi G, Gamba P. Cholesterol Dysmetabolism in Alzheimer's Disease: A Starring Role for Astrocytes? Antioxidants (Basel) 2021; 10:antiox10121890. [PMID: 34943002 PMCID: PMC8750262 DOI: 10.3390/antiox10121890] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 01/19/2023] Open
Abstract
In recent decades, the impairment of cholesterol metabolism in the pathogenesis of Alzheimer’s disease (AD) has been intensively investigated, and it has been recognized to affect amyloid β (Aβ) production and clearance, tau phosphorylation, neuroinflammation and degeneration. In particular, the key role of cholesterol oxidation products, named oxysterols, has emerged. Brain cholesterol metabolism is independent from that of peripheral tissues and it must be preserved in order to guarantee cerebral functions. Among the cells that help maintain brain cholesterol homeostasis, astrocytes play a starring role since they deliver de novo synthesized cholesterol to neurons. In addition, other physiological roles of astrocytes are to modulate synaptic transmission and plasticity and support neurons providing energy. In the AD brain, astrocytes undergo significant morphological and functional changes that contribute to AD onset and development. However, the extent of this contribution and the role played by oxysterols are still unclear. Here we review the current understanding of the physiological role exerted by astrocytes in the brain and their contribution to AD pathogenesis. In particular, we focus on the impact of cholesterol dysmetabolism on astrocyte functions suggesting new potential approaches to develop therapeutic strategies aimed at counteracting AD development.
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