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Heuer SE, Bloss EB, Howell GR. Strategies to dissect microglia-synaptic interactions during aging and in Alzheimer's disease. Neuropharmacology 2024; 254:109987. [PMID: 38705570 DOI: 10.1016/j.neuropharm.2024.109987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/29/2024] [Accepted: 05/02/2024] [Indexed: 05/07/2024]
Abstract
Age is the largest risk factor for developing Alzheimer's disease (AD), a neurodegenerative disorder that causes a progressive and severe dementia. The underlying cause of cognitive deficits seen in AD is thought to be the disconnection of neural circuits that control memory and executive functions. Insight into the mechanisms by which AD diverges from normal aging will require identifying precisely which cellular events are driven by aging and which are impacted by AD-related pathologies. Since microglia, the brain-resident macrophages, are known to have critical roles in the formation and maintenance of neural circuits through synaptic pruning, they are well-positioned to modulate synaptic connectivity in circuits sensitive to aging or AD. In this review, we provide an overview of the current state of the field and on emerging technologies being employed to elucidate microglia-synaptic interactions in aging and AD. We also discuss the importance of leveraging genetic diversity to study how these interactions are shaped across more realistic contexts. We propose that these approaches will be essential to define specific aging- and disease-relevant trajectories for more personalized therapeutics aimed at reducing the effects of age or AD pathologies on the brain. This article is part of the Special Issue on "Microglia".
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Affiliation(s)
- Sarah E Heuer
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Erik B Bloss
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
| | - Gareth R Howell
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, MA, 02111, USA; Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, 04469, USA.
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2
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Regele-Blasco E, Palmer LM. The plasticity of pyramidal neurons in the behaving brain. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230231. [PMID: 38853566 DOI: 10.1098/rstb.2023.0231] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 04/23/2024] [Indexed: 06/11/2024] Open
Abstract
Neurons are plastic. That is, they change their activity according to different behavioural conditions. This endows pyramidal neurons with an incredible computational power for the integration and processing of synaptic inputs. Plasticity can be investigated at different levels of investigation within a single neuron, from spines to dendrites, to synaptic input. Although most of our knowledge stems from the in vitro brain slice preparation, plasticity plays a vital role during behaviour by providing a flexible substrate for the execution of appropriate actions in our ever-changing environment. Owing to advances in recording techniques, the plasticity of neurons and the neural networks in which they are embedded is now beginning to be realized in the in vivo intact brain. This review focuses on the structural and functional synaptic plasticity of pyramidal neurons, with a specific focus on the latest developments from in vivo studies. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Elena Regele-Blasco
- The Florey Institute of Neuroscience and Mental Health, The Florey Department of Neuroscience and Mental Health, University of Melbourne , Victoria 3052, Australia
| | - Lucy M Palmer
- The Florey Institute of Neuroscience and Mental Health, The Florey Department of Neuroscience and Mental Health, University of Melbourne , Victoria 3052, Australia
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3
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Wang N, Zhu B, Allnutt MA, Grijalva RM, Zhao H, Chandra SS. Decoding transcriptomic signatures of cysteine string protein alpha-mediated synapse maintenance. Proc Natl Acad Sci U S A 2024; 121:e2320064121. [PMID: 38833477 PMCID: PMC11181078 DOI: 10.1073/pnas.2320064121] [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: 11/14/2023] [Accepted: 04/19/2024] [Indexed: 06/06/2024] Open
Abstract
Synapse maintenance is essential for generating functional circuitry, and decrement in this process is a hallmark of neurodegenerative disease. Yet, little is known about synapse maintenance in vivo. Cysteine string protein α (CSPα), encoded by the Dnajc5 gene, is a synaptic vesicle chaperone that is necessary for synapse maintenance and linked to neurodegeneration. To investigate the transcriptional changes associated with synapse maintenance, we performed single-nucleus transcriptomics on the cortex of young CSPα knockout (KO) mice and littermate controls. Through differential expression and gene ontology analysis, we observed that both neurons and glial cells exhibit unique signatures in the CSPα KO brain. Significantly, all neuronal classes in CSPα KO brains show strong signatures of repression in synaptic pathways, while up-regulating autophagy-related genes. Through visualization of synapses and autophagosomes by electron microscopy, we confirmed these alterations especially in inhibitory synapses. Glial responses varied by cell type, with microglia exhibiting activation. By imputing cell-cell interactions, we found that neuron-glia interactions were specifically increased in CSPα KO mice. This was mediated by synaptogenic adhesion molecules, with the classical Neurexin1-Neuroligin 1 pair being the most prominent, suggesting that communication of glial cells with neurons is strengthened in CSPα KO mice to preserve synapse maintenance. Together, this study provides a rich dataset of transcriptional changes in the CSPα KO cortex and reveals insights into synapse maintenance and neurodegeneration.
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Affiliation(s)
- Na Wang
- Department of Neurology, Yale University, New Haven, CT06510
- Department of Neuroscience, Yale University, New Haven, CT06510
| | - Biqing Zhu
- Program of Computational Biology and Bioinformatics, Yale University, New Haven, CT06510
- Department of Biostatistics, Yale School of Public Health, New Haven, CT06510
| | - Mary Alice Allnutt
- Department of Neurology, Yale University, New Haven, CT06510
- Department of Neuroscience, Yale University, New Haven, CT06510
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT06510
| | - Rosalie M. Grijalva
- Department of Neuroscience, Yale University, New Haven, CT06510
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT06510
| | - Hongyu Zhao
- Program of Computational Biology and Bioinformatics, Yale University, New Haven, CT06510
- Department of Biostatistics, Yale School of Public Health, New Haven, CT06510
| | - Sreeganga S. Chandra
- Department of Neurology, Yale University, New Haven, CT06510
- Department of Neuroscience, Yale University, New Haven, CT06510
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4
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Kaizuka T, Takumi T. Alteration of synaptic protein composition during developmental synapse maturation. Eur J Neurosci 2024; 59:2894-2914. [PMID: 38571321 DOI: 10.1111/ejn.16304] [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: 05/01/2023] [Revised: 01/02/2024] [Accepted: 02/07/2024] [Indexed: 04/05/2024]
Abstract
The postsynaptic density (PSD) is a collection of specialized proteins assembled beneath the postsynaptic membrane of dendritic spines. The PSD proteome comprises ~1000 proteins, including neurotransmitter receptors, scaffolding proteins and signalling enzymes. Many of these proteins have essential roles in synaptic function and plasticity. During brain development, changes are observed in synapse density and in the stability and shape of spines, reflecting the underlying molecular maturation of synapses. Synaptic protein composition changes in terms of protein abundance and the assembly of protein complexes, supercomplexes and the physical organization of the PSD. Here, we summarize the developmental alterations of postsynaptic protein composition during synapse maturation. We describe major PSD proteins involved in postsynaptic signalling that regulates synaptic plasticity and discuss the effect of altered expression of these proteins during development. We consider the abnormality of synaptic profiles and synaptic protein composition in the brain in neurodevelopmental disorders such as autism spectrum disorders. We also explain differences in synapse development between rodents and primates in terms of synaptic profiles and protein composition. Finally, we introduce recent findings related to synaptic diversity and nanoarchitecture and discuss their impact on future research. Synaptic protein composition can be considered a major determinant and marker of synapse maturation in normality and disease.
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Affiliation(s)
- Takeshi Kaizuka
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Toru Takumi
- Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
- RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
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5
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Flores JC, Zito K. A synapse-specific refractory period for plasticity at individual dendritic spines. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.24.595787. [PMID: 38826343 PMCID: PMC11142223 DOI: 10.1101/2024.05.24.595787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
How newly formed memories are preserved while brain plasticity is ongoing has been a source of debate. One idea is that synapses which experienced recent plasticity become resistant to further plasticity, a type of metaplasticity often referred to as saturation. Here, we probe the local dendritic mechanisms that limit plasticity at recently potentiated synapses. We show that recently potentiated individual synapses exhibit a synapse-specific refractory period for further potentiation. We further found that the refractory period is associated with reduced postsynaptic CaMKII signaling; however, stronger synaptic activation only partially restored the ability for further plasticity. Importantly, the refractory period is released after one hour, a timing that coincides with the enrichment of several postsynaptic proteins to pre-plasticity levels. Notably, increasing the level of the postsynaptic scaffolding protein, PSD95, but not of PSD93, overcomes the refractory period. Our results support a model in which potentiation at a single synapse is sufficient to initiate a synapse-specific refractory period that persists until key postsynaptic proteins regain their steady-state synaptic levels.
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Affiliation(s)
- Juan C. Flores
- Center for Neuroscience, University of California, Davis, CA 95618
| | - Karen Zito
- Center for Neuroscience, University of California, Davis, CA 95618
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6
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Reddien PW. The purpose and ubiquity of turnover. Cell 2024; 187:2657-2681. [PMID: 38788689 DOI: 10.1016/j.cell.2024.04.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/19/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024]
Abstract
Turnover-constant component production and destruction-is ubiquitous in biology. Turnover occurs across organisms and scales, including for RNAs, proteins, membranes, macromolecular structures, organelles, cells, hair, feathers, nails, antlers, and teeth. For many systems, turnover might seem wasteful when degraded components are often fully functional. Some components turn over with shockingly high rates and others do not turn over at all, further making this process enigmatic. However, turnover can address fundamental problems by yielding powerful properties, including regeneration, rapid repair onset, clearance of unpredictable damage and errors, maintenance of low constitutive levels of disrepair, prevention of stable hazards, and transitions. I argue that trade-offs between turnover benefits and metabolic costs, combined with constraints on turnover, determine its presence and rates across distinct contexts. I suggest that the limits of turnover help explain aging and that turnover properties and the basis for its levels underlie this fundamental component of life.
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Affiliation(s)
- Peter W Reddien
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, MIT, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, MIT, Cambridge, MA 02139, USA.
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7
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Rich PD, Thiberge SY, Scott BB, Guo C, Tervo DGR, Brody CD, Karpova AY, Daw ND, Tank DW. Magnetic voluntary head-fixation in transgenic rats enables lifespan imaging of hippocampal neurons. Nat Commun 2024; 15:4154. [PMID: 38755205 PMCID: PMC11099169 DOI: 10.1038/s41467-024-48505-9] [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: 08/16/2023] [Accepted: 05/01/2024] [Indexed: 05/18/2024] Open
Abstract
The precise neural mechanisms within the brain that contribute to the remarkable lifetime persistence of memory are not fully understood. Two-photon calcium imaging allows the activity of individual cells to be followed across long periods, but conventional approaches require head-fixation, which limits the type of behavior that can be studied. We present a magnetic voluntary head-fixation system that provides stable optical access to the brain during complex behavior. Compared to previous systems that used mechanical restraint, there are no moving parts and animals can engage and disengage entirely at will. This system is failsafe, easy for animals to use and reliable enough to allow long-term experiments to be routinely performed. Animals completed hundreds of trials per session of an odor discrimination task that required 2-4 s fixations. Together with a reflectance fluorescence collection scheme that increases two-photon signal and a transgenic Thy1-GCaMP6f rat line, we are able to reliably image the cellular activity in the hippocampus during behavior over long periods (median 6 months), allowing us track the same neurons over a large fraction of animals' lives (up to 19 months).
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Affiliation(s)
- P Dylan Rich
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA.
| | | | - Benjamin B Scott
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, USA
- Center for Systems Neuroscience, Boston University, Boston, MA, USA
- Neurophotonics Center, Boston University, Boston, MA, USA
| | - Caiying Guo
- Janelia Research Campus, Ashburn, VA, USA
- Howard Hughes Medical Institute, Ashburn, VA, USA
| | - D Gowanlock R Tervo
- Janelia Research Campus, Ashburn, VA, USA
- Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Carlos D Brody
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
- Howard Hughes Medical Institute, Princeton University, Princeton, NJ, USA
| | - Alla Y Karpova
- Janelia Research Campus, Ashburn, VA, USA
- Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Nathaniel D Daw
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
- Department of Psychology, Princeton University, Princeton, NJ, USA
| | - David W Tank
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA.
- Bezos Center for Neural Circuit Dynamics, Princeton University, Princeton, NJ, USA.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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Pei J, Zhang C, Zhang X, Zhao Z, Zhang X, Yuan Y. Low-intensity transcranial ultrasound stimulation improves memory in vascular dementia by enhancing neuronal activity and promoting spine formation. Neuroimage 2024; 291:120584. [PMID: 38522806 DOI: 10.1016/j.neuroimage.2024.120584] [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: 11/23/2023] [Revised: 03/01/2024] [Accepted: 03/21/2024] [Indexed: 03/26/2024] Open
Abstract
Memory is closely associated with neuronal activity and dendritic spine formation. Low-intensity transcranial ultrasound stimulation (TUS) improves the memory of individuals with vascular dementia (VD). However, it is unclear whether neuronal activity and dendritic spine formation under ultrasound stimulation are involved in memory improvement in VD. In this study, we found that seven days of TUS improved memory in VD model while simultaneously increasing pyramidal neuron activity, promoting dendritic spine formation, and reducing dendritic spine elimination. These effects lasted for 7 days but disappeared on 14 d after TUS. Neuronal activity and dendritic spine formation strongly corresponded to improvements in memory behavior over time. In addition, we also found that the memory, neuronal activity and dendritic spine of VD mice cannot be restored again by TUS of 7 days after 28 d. Collectively, these findings suggest that TUS increases neuronal activity and promotes dendritic spine formation and is thus important for improving memory in patients with VD.
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Affiliation(s)
- Jiamin Pei
- School of Electrical Engineering, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China
| | - Cong Zhang
- Department of Neurology, Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, The Second Hospital of Hebei Medical University, No.215 Heping Road, Shijiazhuang 050000, China
| | - Xiao Zhang
- Department of Neurology, Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, The Second Hospital of Hebei Medical University, No.215 Heping Road, Shijiazhuang 050000, China
| | - Zhe Zhao
- School of Electrical Engineering, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China
| | - Xiangjian Zhang
- Department of Neurology, Hebei Key Laboratory of Vascular Homeostasis and Hebei Collaborative Innovation Center for Cardio-cerebrovascular Disease, The Second Hospital of Hebei Medical University, No.215 Heping Road, Shijiazhuang 050000, China.
| | - Yi Yuan
- School of Electrical Engineering, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China; Key Laboratory of Intelligent Rehabilitation and Neuromodulation of Hebei Province, Yanshan University, No.438 Hebei Street, Qinhuangdao 066004, China.
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9
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González-Cota AL, Martínez-Flores D, Rosendo-Pineda MJ, Vaca L. NMDA receptor-mediated Ca 2+ signaling: Impact on cell cycle regulation and the development of neurodegenerative diseases and cancer. Cell Calcium 2024; 119:102856. [PMID: 38408411 DOI: 10.1016/j.ceca.2024.102856] [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: 09/11/2023] [Revised: 01/08/2024] [Accepted: 02/07/2024] [Indexed: 02/28/2024]
Abstract
NMDA receptors are Ca2+-permeable ligand-gated ion channels that mediate fast excitatory transmission in the central nervous system. NMDA receptors regulate the proliferation and differentiation of neural progenitor cells and also play critical roles in neural plasticity, memory, and learning. In addition to their physiological role, NMDA receptors are also involved in glutamate-mediated excitotoxicity, which results from excessive glutamate stimulation, leading to Ca2+ overload, and ultimately to neuronal death. Thus, NMDA receptor-mediated excitotoxicity has been linked to several neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, dementia, and stroke. Interestingly, in addition to its effects on cell death, aberrant expression or activation of NMDA receptors is also involved in pathological cellular proliferation, and is implicated in the invasion and proliferation of various types of cancer. These disorders are thought to be related to the contribution of NMDA receptors to cell proliferation and cell death through cell cycle modulation. This review aims to discuss the evidence implicating NMDA receptor activity in cell cycle regulation and the link between aberrant NMDA receptor activity and the development of neurodegenerative diseases and cancer due to cell cycle dysregulation. The information presented here will provide insights into the signaling pathways and the contribution of NMDA receptors to these diseases, and suggests that NMDA receptors are promising targets for the prevention and treatment of these diseases, which are leading causes of death and disability worldwide.
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Affiliation(s)
- Ana L González-Cota
- Instituto de Fisiología Celular, Departamento de Biología Celular y Desarrollo, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Daniel Martínez-Flores
- Instituto de Fisiología Celular, Departamento de Biología Celular y Desarrollo, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Margarita Jacaranda Rosendo-Pineda
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico
| | - Luis Vaca
- Instituto de Fisiología Celular, Departamento de Biología Celular y Desarrollo, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, 04510, Mexico.
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10
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Yu Y, Adsit LM, Smith IT. Comprehensive software suite for functional analysis and synaptic input mapping of dendritic spines imaged in vivo. NEUROPHOTONICS 2024; 11:024307. [PMID: 38628980 PMCID: PMC11021036 DOI: 10.1117/1.nph.11.2.024307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 04/19/2024]
Abstract
Significance Advances in genetically encoded sensors and two-photon imaging have unlocked functional imaging at the level of single dendritic spines. Synaptic activity can be measured in real time in awake animals. However, tools are needed to facilitate the analysis of the large datasets acquired by the approach. Commonly available software suites for imaging calcium transients in cell bodies are ill-suited for spine imaging as dendritic spines have structural characteristics distinct from those of the cell bodies. We present an automated tuning analysis tool (AUTOTUNE), which provides analysis routines specifically developed for the extraction and analysis of signals from subcellular compartments, including dendritic subregions and spines. Aim Although the acquisition of in vivo functional synaptic imaging data is increasingly accessible, a hurdle remains in the computation-heavy analyses of the acquired data. The aim of this study is to overcome this barrier by offering a comprehensive software suite with a user-friendly interface for easy access to nonprogrammers. Approach We demonstrate the utility and effectiveness of our software with demo analyses of dendritic imaging data acquired from layer 2/3 pyramidal neurons in mouse V1 in vivo. A user manual and demo datasets are also provided. Results AUTOTUNE provides a robust workflow for analyzing functional imaging data from neuronal dendrites. Features include source image registration, segmentation of regions-of-interest and detection of structural turnover, fluorescence transient extraction and smoothing, subtraction of signals from putative backpropagating action potentials, and stimulus and behavioral parameter response tuning analyses. Conclusions AUTOTUNE is open-source and extendable for diverse functional synaptic imaging experiments. The ease of functional characterization of dendritic spine activity provided by our software can accelerate new functional studies that complement decades of morphological studies of dendrites, and further expand our understanding of neural circuits in health and in disease.
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Affiliation(s)
- Yiyi Yu
- University of California, Santa Barbara, Department of Electrical and Computer Engineering, Santa Barbara, California, United States
| | - Liam M. Adsit
- University of California, Santa Barbara, Department of Molecular, Cellular and Developmental Biology, Santa Barbara, California, United States
| | - Ikuko T. Smith
- University of California, Santa Barbara, Department of Molecular, Cellular and Developmental Biology, Santa Barbara, California, United States
- University of California, Santa Barbara, Neuroscience Research Institute, Santa Barbara, California, United States
- University of California, Santa Barbara, Department of Psychological and Brain Sciences, Santa Barbara, California, United States
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11
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Golmohammadi M, Mahmoudian M, Hasan EK, Alshahrani SH, Romero-Parra RM, Malviya J, Hjazi A, Najm MAA, Almulla AF, Zamanian MY, Kadkhodaei M, Mousavi N. Neuroprotective effects of riluzole in Alzheimer's disease: A comprehensive review. Fundam Clin Pharmacol 2024; 38:225-237. [PMID: 37753585 DOI: 10.1111/fcp.12955] [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: 06/13/2023] [Revised: 08/18/2023] [Accepted: 08/24/2023] [Indexed: 09/28/2023]
Abstract
BACKGROUND Despite several hundred clinical trials of drugs that initially showed promise, there has been limited clinical improvement in Alzheimer's disease (AD). This may be attributed to the existence of at least 25 abnormal cellular pathways that underlie the disease. It is improbable for a single drug to address all or most of these pathways, thus even drugs that show promise when administered alone are unlikely to produce significant results. According to previous studies, eight drugs, namely, dantrolene, erythropoietin, lithium, memantine, minocycline, piracetam, riluzole, and silymarin, have been found to target multiple pathways that are involved in the development of AD. Among these drugs, riluzole is currently indicated for the treatment of medical conditions in both adult patients and children and has gained increased attention from scientists due to its potential in the excitotoxic hypothesis of neurodegenerative diseases. OBJECTIVE The aim of this study was to investigate the effects of drugs on AD based on cellular and molecular mechanisms. METHODS The literature search for this study utilized the Scopus, ScienceDirect, PubMed, and Google Scholar databases to identify relevant articles. RESULTS Riluzole exerts its effects in AD through diverse pathways including the inhibition of voltage-dependent sodium and calcium channels, blocking AMPA and NMDA receptors and inhibiting the release of glutamic acid release and stimulation of EAAT1-EAAT2. CONCLUSION In this review article, we aimed to review the neuroprotective properties of riluzole, a glutamate modulator, in AD, which could benefit patients with the disease.
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Affiliation(s)
- Maryam Golmohammadi
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | | | | | | | - Jitendra Malviya
- Department of Life Sciences and Biological Sciences, IES University, Bhopal, Madhya Pradesh, India
| | - Ahmed Hjazi
- Department of Medical Laboratory Sciences, College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia
| | - Mazin A A Najm
- Pharmaceutical Chemistry Department, College of Pharmacy, Al-Ayen University, Thi-Qar, Iraq
| | - Abbas F Almulla
- Medical Laboratory Technology Department, College of Medical Technology, The Islamic University, Najaf, Iraq
| | - Mohammad Yasin Zamanian
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
- Department of Pharmacology and Toxicology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mona Kadkhodaei
- Department of Surgery, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Nazanin Mousavi
- Department of Psychology, Imam Khomeini International University, Qazvin, Iran
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12
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Kisner A, Polter AM. Maturation of glutamatergic transmission onto dorsal raphe serotonergic neurons. J Neurophysiol 2024; 131:626-637. [PMID: 38380827 DOI: 10.1152/jn.00037.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/01/2024] [Accepted: 02/19/2024] [Indexed: 02/22/2024] Open
Abstract
Serotonergic neurons in the dorsal raphe nucleus (DRN) play important roles early in postnatal development in the maturation and modulation of higher-order emotional, sensory, and cognitive circuitry. The pivotal functions of these cells in brain development make them a critical substrate by which early experience can be wired into the brain. In this study, we investigated the maturation of synapses onto dorsal raphe serotonergic neurons in typically developing male and female mice using whole cell patch-clamp recordings in ex vivo brain slices. We show that while inhibition of these neurons is relatively stable across development, glutamatergic synapses greatly increase in strength between postnatal day 6 (P6) and P21-23. In contrast to forebrain regions, where the components making up glutamatergic synapses are dynamic across early life, we find that DRN excitatory synapses maintain a very high ratio of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) to N-methyl-d-aspartate (NMDA) receptors and a rectifying component of the AMPA response until adulthood. Overall, these findings reveal that the development of serotonergic neurons is marked by a significant refinement of glutamatergic synapses during the first three postnatal weeks. This suggests this time is a sensitive period of heightened plasticity for the integration of information from upstream brain areas. Genetic and environmental insults during this period could lead to alterations in serotonergic output, impacting both the development of forebrain circuits and lifelong neuromodulatory actions.NEW & NOTEWORTHY Serotonergic neurons are regulators of both the development of and ongoing activity in neuronal circuits controlling affective, cognitive, and sensory processing. Here, we characterize the maturation of extrinsic synaptic inputs onto these cells, showing that the first three postnatal weeks are a period of synaptic refinement and a potential window for experience-dependent plasticity in response to both enrichment and adversity.
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Affiliation(s)
- Alexandre Kisner
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
| | - Abigail M Polter
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, United States
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Misrani A, Tabassum S, Zhang ZY, Tan SH, Long C. Urolithin A Prevents Sleep-deprivation-induced Neuroinflammation and Mitochondrial Dysfunction in Young and Aged Mice. Mol Neurobiol 2024; 61:1448-1466. [PMID: 37725214 DOI: 10.1007/s12035-023-03651-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: 10/26/2022] [Accepted: 09/10/2023] [Indexed: 09/21/2023]
Abstract
Sleep deprivation (SD) has reached epidemic proportions worldwide and negatively affects people of all ages. Cognitive impairment induced by SD involves neuroinflammation and mitochondrial dysfunction, but the underlying mechanisms are largely unknown. Urolithin A (UA) is a natural compound that can reduce neuroinflammation and improve mitochondrial health, but its therapeutic effects in a SD model have not yet been studied. Young (3-months old) and aged (12-months old) mice were sleep deprived for 24 h, and UA (2.5 mg/kg or 10 mg/kg) was injected intraperitoneally for 7 consecutive days before the SD period. Immunofluorescent staining, western blotting, and RT-PCR were employed to evaluate levels of proteins involved in neuroinflammation and mitochondrial function. Transmission electron microscope and Golgi-Cox staining were used to evaluate mitochondrial and neuronal morphology, respectively. Finally, contextual fear conditioning and the Morris water maze test were conducted to assess hippocampal learning and memory. In the hippocampus of young (3 months-old) and aged (12 months-old) mice subjected to 24 h SD, pretreatment with UA prevented the activation of microglia and astrocytes, NF-κB-NLRP3 signaling and IL-1β, IL6, TNF-α cytokine production, thus ameliorating neuroinflammation. Furthermore, UA also attenuated SD-induced mitochondrial dysfunction, normalized autophagy and mitophagy and protected hippocampal neuronal morphology. Finally, UA prevented SD-induced hippocampal memory impairment. Cumulatively, the results show that UA imparts cognitive protection by reducing neuroinflammation and enhancing mitochondrial function in SD mice. This suggests that UA shows promise as a therapeutic for the treatment of SD-induced neurological disorders.
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Affiliation(s)
- Afzal Misrani
- South China Normal University-Panyu Central Hospital Joint Laboratory of Translational Medical Research, Panyu Central Hospital, Guangzhou, 511400, China
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Sidra Tabassum
- South China Normal University-Panyu Central Hospital Joint Laboratory of Translational Medical Research, Panyu Central Hospital, Guangzhou, 511400, China
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Zai-Yong Zhang
- Department of Cardiology, Panyu Central Hospital, Guangzhou, 511400, China
- Cardiovascular Institute of Panyu District, Guangzhou, 511400, China
| | - Shao-Hua Tan
- Department of Neurology, Panyu District Central Hospital, Guangzhou, 511400, China
| | - Cheng Long
- South China Normal University-Panyu Central Hospital Joint Laboratory of Translational Medical Research, Panyu Central Hospital, Guangzhou, 511400, China.
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China.
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14
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Seitzman BA, Reynoso FJ, Mitchell TJ, Bice AR, Jarang A, Wang X, Mpoy C, Strong L, Rogers BE, Yuede CM, Rubin JB, Perkins SM, Bauer AQ. Functional network disorganization and cognitive decline following fractionated whole-brain radiation in mice. GeroScience 2024; 46:543-562. [PMID: 37749370 PMCID: PMC10828348 DOI: 10.1007/s11357-023-00944-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 09/11/2023] [Indexed: 09/27/2023] Open
Abstract
Cognitive dysfunction following radiotherapy (RT) is one of the most common complications associated with RT delivered to the brain, but the precise mechanisms behind this dysfunction are not well understood, and to date, there are no preventative measures or effective treatments. To improve patient outcomes, a better understanding of the effects of radiation on the brain's functional systems is required. Functional magnetic resonance imaging (fMRI) has shown promise in this regard, however, compared to neural activity, hemodynamic measures of brain function are slow and indirect. Understanding how RT acutely and chronically affects functional brain organization requires more direct examination of temporally evolving neural dynamics as they relate to cerebral hemodynamics for bridging with human studies. In order to adequately study the underlying mechanisms of RT-induced cognitive dysfunction, the development of clinically mimetic RT protocols in animal models is needed. To address these challenges, we developed a fractionated whole-brain RT protocol (3Gy/day for 10 days) and applied longitudinal wide field optical imaging (WFOI) of neural and hemodynamic brain activity at 1, 2, and 3 months post RT. At each time point, mice were subject to repeated behavioral testing across a variety of sensorimotor and cognitive domains. Disruptions in cortical neuronal and hemodynamic activity observed 1 month post RT were significantly worsened by 3 months. While broad changes were observed in functional brain organization post RT, brain regions most impacted by RT occurred within those overlapping with the mouse default mode network and other association areas similar to prior reports in human subjects. Further, significant cognitive deficits were observed following tests of novel object investigation and responses to auditory and contextual cues after fear conditioning. Our results fill a much-needed gap in understanding the effects of whole-brain RT on systems level brain organization and how RT affects neuronal versus hemodynamic signaling in the cortex. Having established a clinically-relevant injury model, future studies can examine therapeutic interventions designed to reduce neuroinflammation-based injury following RT. Given the overlap of sequelae that occur following RT with and without chemotherapy, these tools can also be easily incorporated to examine chemotherapy-related cognitive impairment.
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Affiliation(s)
- Benjamin A Seitzman
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Francisco J Reynoso
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Timothy J Mitchell
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Annie R Bice
- Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, 660 S. Euclid Ave, Campus Box 8225, St. Louis, MO, 63110, USA
| | - Anmol Jarang
- Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, 660 S. Euclid Ave, Campus Box 8225, St. Louis, MO, 63110, USA
| | - Xiaodan Wang
- Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, 660 S. Euclid Ave, Campus Box 8225, St. Louis, MO, 63110, USA
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Cedric Mpoy
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Lori Strong
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Buck E Rogers
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA
| | - Carla M Yuede
- Department of Psychiatry, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | - Joshua B Rubin
- Department of Pediatrics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | - Stephanie M Perkins
- Department of Radiation Oncology, School of Medicine, Washington University in St. Louis, 4921 Parkview Place, Campus Box 8224, St. Louis, MO, 63110, USA.
| | - Adam Q Bauer
- Mallinckrodt Institute of Radiology, School of Medicine, Washington University in St. Louis, 660 S. Euclid Ave, Campus Box 8225, St. Louis, MO, 63110, USA.
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA.
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15
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Hu G, Chen A, Ye J, Liu Q, Wang J, Fan C, Wang X, Huang M, Dai M, Shi X, Gu Y. A developmental critical period for ocular dominance plasticity of binocular neurons in mouse superior colliculus. Cell Rep 2024; 43:113667. [PMID: 38184852 DOI: 10.1016/j.celrep.2023.113667] [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: 05/11/2023] [Revised: 09/29/2023] [Accepted: 12/25/2023] [Indexed: 01/09/2024] Open
Abstract
Detecting visual features in the environment is crucial for animals' survival. The superior colliculus (SC) is implicated in motion detection and processing, whereas how the SC integrates visual inputs from the two eyes remains unclear. Using in vivo electrophysiology, we show that mouse SC contains many binocular neurons that display robust ocular dominance (OD) plasticity in a critical period during early development, which is similar to, but not dependent on, the primary visual cortex. NR2A- and NR2B-containing N-methyl-D-aspartate (NMDA) receptors play an essential role in the regulation of SC plasticity. Blocking NMDA receptors can largely prevent the impairment of predatory hunting caused by monocular deprivation, indicating that maintaining the binocularity of SC neurons is required for efficient hunting behavior. Together, our studies reveal the existence and function of OD plasticity in SC, which broadens our understanding of the development of subcortical visual circuitry relating to motion detection and predatory hunting.
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Affiliation(s)
- Guanglei Hu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China; School of Life Sciences, Westlake University, Hangzhou 310000, China
| | - Ailin Chen
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China
| | - Jingjing Ye
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China; Medical College of Optometry and Ophthalmology, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
| | - Qiong Liu
- School of Life Sciences, Westlake University, Hangzhou 310000, China
| | - Jiafeng Wang
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China
| | - Cunxiu Fan
- Jiading Branch of Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, 800 Huangjiahuayuan Road, Shanghai 201803, China
| | - Xiaoqing Wang
- Department of Dermatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
| | - Mengqi Huang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Menghan Dai
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China
| | - Xuefeng Shi
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300020, China; Medical College of Optometry and Ophthalmology, Shandong University of Traditional Chinese Medicine, Jinan 250014, China; Institute of Ophthalmology, Nankai University, Tianjin 300020, China.
| | - Yu Gu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
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16
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Sohn J. Synaptic configuration and reconfiguration in the neocortex are spatiotemporally selective. Anat Sci Int 2024; 99:17-33. [PMID: 37837522 PMCID: PMC10771605 DOI: 10.1007/s12565-023-00743-5] [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: 05/24/2023] [Accepted: 09/14/2023] [Indexed: 10/16/2023]
Abstract
Brain computation relies on the neural networks. Neurons extend the neurites such as dendrites and axons, and the contacts of these neurites that form chemical synapses are the biological basis of signal transmissions in the central nervous system. Individual neuronal outputs can influence the other neurons within the range of the axonal spread, while the activities of single neurons can be affected by the afferents in their somatodendritic fields. The morphological profile, therefore, binds the functional role each neuron can play. In addition, synaptic connectivity among neurons displays preference based on the characteristics of presynaptic and postsynaptic neurons. Here, the author reviews the "spatial" and "temporal" connection selectivity in the neocortex. The histological description of the neocortical circuitry depends primarily on the classification of cell types, and the development of gene engineering techniques allows the cell type-specific visualization of dendrites and axons as well as somata. Using genetic labeling of particular cell populations combined with immunohistochemistry and imaging at a subcellular spatial resolution, we revealed the "spatial selectivity" of cortical wirings in which synapses are non-uniformly distributed on the subcellular somatodendritic domains in a presynaptic cell type-specific manner. In addition, cortical synaptic dynamics in learning exhibit presynaptic cell type-dependent "temporal selectivity": corticocortical synapses appear only transiently during the learning phase, while learning-induced new thalamocortical synapses persist, indicating that distinct circuits may supervise learning-specific ephemeral synapse and memory-specific immortal synapse formation. The selectivity of spatial configuration and temporal reconfiguration in the neural circuitry may govern diverse functions in the neocortex.
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Affiliation(s)
- Jaerin Sohn
- Department of Systematic Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka, 565-0871, Japan.
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17
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Sortino R, Cunquero M, Castro-Olvera G, Gelabert R, Moreno M, Riefolo F, Matera C, Fernàndez-Castillo N, Agnetta L, Decker M, Lluch JM, Hernando J, Loza-Alvarez P, Gorostiza P. Three-Photon Infrared Stimulation of Endogenous Neuroreceptors in Vivo. Angew Chem Int Ed Engl 2023; 62:e202311181. [PMID: 37823736 DOI: 10.1002/anie.202311181] [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: 08/02/2023] [Revised: 09/30/2023] [Accepted: 10/11/2023] [Indexed: 10/13/2023]
Abstract
To interrogate neural circuits and crack their codes, in vivo brain activity imaging must be combined with spatiotemporally precise stimulation in three dimensions using genetic or pharmacological specificity. This challenge requires deep penetration and focusing as provided by infrared light and multiphoton excitation, and has promoted two-photon photopharmacology and optogenetics. However, three-photon brain stimulation in vivo remains to be demonstrated. We report the regulation of neuronal activity in zebrafish larvae by three-photon excitation of a photoswitchable muscarinic agonist at 50 pM, a billion-fold lower concentration than used for uncaging, and with mid-infrared light of 1560 nm, the longest reported photoswitch wavelength. Robust, physiologically relevant photoresponses allow modulating brain activity in wild-type animals with spatiotemporal and pharmacological precision. Computational calculations predict that azobenzene-based ligands have high three-photon absorption cross-section and can be used directly with pulsed infrared light. The expansion of three-photon pharmacology will deeply impact basic neurobiology and neuromodulation phototherapies.
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Affiliation(s)
- Rosalba Sortino
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology, 08028, Barcelona, Spain
- CIBER-BBN, ISCIII, 28029, Madrid, Spain
| | - Marina Cunquero
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Gustavo Castro-Olvera
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Ricard Gelabert
- Departament de Química, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Spain
| | - Miquel Moreno
- Departament de Química, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Spain
| | - Fabio Riefolo
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology, 08028, Barcelona, Spain
- CIBER-BBN, ISCIII, 28029, Madrid, Spain
- Current address: Teamit Institute, Partnerships, Barcelona Health Hub, 08025, Barcelona, Spain
| | - Carlo Matera
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology, 08028, Barcelona, Spain
- CIBER-BBN, ISCIII, 28029, Madrid, Spain
- Current address: Department of Pharmaceutical Sciences, University of Milan, 20133, Milan, Italy
| | - Noèlia Fernàndez-Castillo
- CIBER-BBN, ISCIII, 28029, Madrid, Spain
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, 08028, Barcelona, Spain
- Institut de Biomedicina de la, Universitat de Barcelona (IBUB), 08028, Barcelona, Spain
- Institut de Recerca Sant Joan de Déu (IRSJD), 08950, Esplugues de Llobregat, Spain
| | - Luca Agnetta
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Ludwig Maximilian University of Würzburg, 97074, Würzburg, Germany
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy and Food Chemistry, Ludwig Maximilian University of Würzburg, 97074, Würzburg, Germany
| | - José M Lluch
- Departament de Química, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Spain
- Institut de Biotecnologia i de Biomedicina (IBB), UAB, 08193, Bellaterra, Spain
| | - Jordi Hernando
- Departament de Química, Universitat Autònoma de Barcelona (UAB), 08193, Bellaterra, Spain
| | - Pablo Loza-Alvarez
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Castelldefels (Barcelona), Spain
| | - Pau Gorostiza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology, 08028, Barcelona, Spain
- CIBER-BBN, ISCIII, 28029, Madrid, Spain
- Catalan Institution of Research and Advanced Studies (ICREA), 08010, Barcelona, Spain
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18
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Kogan E, Lu J, Zuo Y. Cortical circuit dynamics underlying motor skill learning: from rodents to humans. Front Mol Neurosci 2023; 16:1292685. [PMID: 37965043 PMCID: PMC10641381 DOI: 10.3389/fnmol.2023.1292685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 10/11/2023] [Indexed: 11/16/2023] Open
Abstract
Motor learning is crucial for the survival of many animals. Acquiring a new motor skill involves complex alterations in both local neural circuits in many brain regions and long-range connections between them. Such changes can be observed anatomically and functionally. The primary motor cortex (M1) integrates information from diverse brain regions and plays a pivotal role in the acquisition and refinement of new motor skills. In this review, we discuss how motor learning affects the M1 at synaptic, cellular, and circuit levels. Wherever applicable, we attempt to relate and compare findings in humans, non-human primates, and rodents. Understanding the underlying principles shared by different species will deepen our understanding of the neurobiological and computational basis of motor learning.
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Affiliation(s)
| | | | - Yi Zuo
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA, United States
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19
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Vega-Rivera NM, González-Trujano ME, Luna-Angula A, Sánchez-Chapul L, Estrada-Camarena E. Antidepressant-like effects of the Punica granatum and citalopram combination are associated with structural changes in dendritic spines of granule cells in the dentate gyrus of rats. Front Pharmacol 2023; 14:1211663. [PMID: 37900157 PMCID: PMC10613096 DOI: 10.3389/fphar.2023.1211663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 08/31/2023] [Indexed: 10/31/2023] Open
Abstract
Introduction: Natural products such as phytoestrogens-enriched foods or supplements have been considered as an alternative therapy to reduce depressive symptoms associated with menopause. It is known that the aqueous extract of Punica granatum (AE-PG) exerts antidepressant-like effects by activating β-estrogen receptors and facilitates the antidepressant response of the clinical drug citalopram (CIT). However, the effects on neuroplasticity are unknown. Objectvie investigated the antidepressant-like response of combining AE-PG and CIT at sub-optimal doses, analyzing their effects on the formation and maturation of dendrite spines in granule cells as well as on the dendrite complexity. Methods: Ovariectomized Wistar rats (3-month-old) were randomly assigned to one of the following groups: A) control (saline solution as vehicle of CIT and AE-PG, B) AE-PG at a sub-threshold dose (vehicle of CIT plus AE-PG at 0.125 mg/kg), C) CIT at a sub-threshold dose (0.77 mg/kg plus vehicle of AE-PG), and D) a combination of CIT plus AE-PG (0.125 mg/kg and 0.77 mg/kg, respectively). All rats were treated intraperitoneally for 14 days. Antidepressant-like effects were evaluated using the force swimming test test (FST). The complexity of dendrites and the number and morphology of dendrite spines of neurons were assessed in the dentate gyrus after Golgi-Cox impregnation. The expressions of the mature brain-derived neurotrophic factor (mBDNF) in plasma and of mBDNF and synaptophysin in the hippocampus, as markers of synaptogenesis, were also determined. Results: Administration of CIT combined with AE-PG, but not alone, induced a significant antidepressant-like effect in the FST with an increase in the dendritic complexity and the number of dendritic spines in the dentate gyrus (DG) of the hippocampus, revealed by the thin and stubby categories of neurons at the granular cell layer. At the same time, an increase of mBDNF and synaptophysin expression was observed in the hippocampus of rats that received the combination of AE-PG and CIT.
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Affiliation(s)
- Nelly-Maritza Vega-Rivera
- Laboratorio de Neuropsicofarmacología, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría “Ramón de la Fuente Muñiz”, Mexico City, Mexico
| | - María Eva González-Trujano
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Alexandra Luna-Angula
- Laboratorio de Enfermedades Neuromusculares, División de Neurociencias Clínicas, Instituto Nacional de Rehabilitación “Luis Guillermo Ibarra Ibarra”, Mexico City, Mexico
| | - Laura Sánchez-Chapul
- Laboratorio de Enfermedades Neuromusculares, División de Neurociencias Clínicas, Instituto Nacional de Rehabilitación “Luis Guillermo Ibarra Ibarra”, Mexico City, Mexico
| | - Erika Estrada-Camarena
- Laboratorio de Neuropsicofarmacología, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría “Ramón de la Fuente Muñiz”, Mexico City, Mexico
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20
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Huang X, Lian YE, Qiu L, Yu X, Miao J, Zhang S, Zhang Z, Zhang X, Chen J, Bai Y, Li L. Quantitative Assessment of Hepatic Steatosis Using Label-Free Multiphoton Imaging and Customized Image Processing Program. J Transl Med 2023; 103:100223. [PMID: 37517702 DOI: 10.1016/j.labinv.2023.100223] [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: 05/07/2023] [Revised: 07/17/2023] [Accepted: 07/24/2023] [Indexed: 08/01/2023] Open
Abstract
Nonalcoholic fatty liver disease is rapidly becoming one of the most common causes of chronic liver disease worldwide and is the leading cause of liver-related morbidity and mortality. A quantitative assessment of the degree of steatosis would be more advantageous for diagnostic evaluation and exploring the patterns of disease progression. Here, multiphoton microscopy, based on the second harmonic generation and 2-photon excited fluorescence, was used to label-free image the samples of nonalcoholic fatty liver. Imaging results confirm that multiphoton microscopy is capable of directly visualizing important pathologic features such as normal hepatocytes, hepatic steatosis, Mallory bodies, necrosis, inflammation, collagen deposition, microvessel, and so on and is a reliable auxiliary tool for the diagnosis of nonalcoholic fatty liver disease. Furthermore, we developed an image segmentation algorithm to simultaneously assess hepatic steatosis and fibrotic changes, and quantitative results reveal that there is a correlation between the degree of steatosis and collagen content. We also developed a feature extraction program to precisely display the spatial distribution of hepatocyte steatosis in tissues. These studies may be beneficial for a better clinical understanding of the process of steatosis as well as for exploring possible therapeutic targets.
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Affiliation(s)
- Xingxin Huang
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Yuan-E Lian
- Department of Pathology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Lida Qiu
- College of Physics and Electronic Information Engineering, Minjiang University, Fuzhou, China
| | - XunBin Yu
- Department of Pathology, Fujian Provincial Hospital, Fuzhou, China
| | - Jikui Miao
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Shichao Zhang
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Zheng Zhang
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Xiong Zhang
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Jianxin Chen
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China
| | - Yannan Bai
- Department of Hepatobiliary and Pancreatic Surgery, Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China.
| | - Lianhuang Li
- Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou, China.
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21
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Xin W, Kaneko M, Roth RH, Zhang A, Nocera S, Ding JB, Stryker MP, Chan JR. Adolescent oligodendrogenesis and myelination restrict experience-dependent neuronal plasticity in adult visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560231. [PMID: 37808666 PMCID: PMC10557765 DOI: 10.1101/2023.09.29.560231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
BACKGROUND Developmental myelination is a protracted process in the mammalian brain. One theory for why oligodendrocytes mature so slowly posits that myelination may stabilize neuronal circuits and temper neuronal plasticity as animals age. We tested this hypothesis in the visual cortex, which has a well-defined critical period for experience-dependent neuronal plasticity. OBJECTIVES/METHODS To prevent myelin progression, we conditionally deleted Myrf, a transcription factor necessary for oligodendrocyte maturation, from oligodendrocyte precursor cells (Myrf cKO) in adolescent mice. To induce experience-dependent plasticity, adult control and Myrf cKO mice were monocularly deprived by eyelid suture. Functional and structural neuronal plasticity in the visual cortex were assessed in vivo by intrinsic signal optical imaging and longitudinal two photon imaging of dendritic spines, respectively. RESULTS During adolescence, visual experience modulated the rate of oligodendrocyte maturation in visual cortex. Myrf deletion from oligodendrocyte precursors during adolescence led to inhibition of oligodendrocyte maturation and myelination that persisted into adulthood. Following monocular deprivation, visual cortex activity in response to visual stimulation of the deprived eye remained stable in adult control mice, as expected for post-critical period animals. By contrast, visual cortex responses to the deprived eye decreased significantly following monocular deprivation in adult Myrf cKO mice, reminiscent of the plasticity observed in adolescent mice. Furthermore, visual cortex neurons in adult Myrf cKO mice had fewer dendritic spines and a higher level of spine turnover. Finally, monocular deprivation induced spatially coordinated spine size decreases in adult Myrf cKO, but not control, mice. CONCLUSIONS These results demonstrate a critical role for oligodendrocytes in shaping the maturation and stabilization of cortical circuits and support the concept of myelin acting as a brake on neuronal plasticity during development.
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Affiliation(s)
- Wendy Xin
- Department of Neurology, Weill Institute for Neurosciences, University of California San Francisco
| | - Megumi Kaneko
- Department of Physiology, Kavli Institute for Fundamental Neuroscience and Weill Institute for Neurosciences, University of California San Francisco
| | - Richard H Roth
- Departments of Neurosurgery and Neurology and Neurological Science, Stanford University
| | - Albert Zhang
- Department of Neurology, Weill Institute for Neurosciences, University of California San Francisco
| | - Sonia Nocera
- Department of Neurology, Weill Institute for Neurosciences, University of California San Francisco
| | - Jun B Ding
- Departments of Neurosurgery and Neurology and Neurological Science, Stanford University
| | - Michael P Stryker
- Department of Physiology, Kavli Institute for Fundamental Neuroscience and Weill Institute for Neurosciences, University of California San Francisco
| | - Jonah R Chan
- Department of Neurology, Weill Institute for Neurosciences, University of California San Francisco
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22
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Ugarte G, Piña R, Contreras D, Godoy F, Rubio D, Rozas C, Zeise M, Vidal R, Escobar J, Morales B. Attention Deficit-Hyperactivity Disorder (ADHD): From Abnormal Behavior to Impairment in Synaptic Plasticity. BIOLOGY 2023; 12:1241. [PMID: 37759640 PMCID: PMC10525904 DOI: 10.3390/biology12091241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/08/2023] [Accepted: 09/10/2023] [Indexed: 09/29/2023]
Abstract
Attention deficit-hyperactivity disorder (ADHD) is a neurodevelopmental disorder with high incidence in children and adolescents characterized by motor hyperactivity, impulsivity, and inattention. Magnetic resonance imaging (MRI) has revealed that neuroanatomical abnormalities such as the volume reduction in the neocortex and hippocampus are shared by several neuropsychiatric diseases such as schizophrenia, autism spectrum disorder and ADHD. Furthermore, the abnormal development and postnatal pruning of dendritic spines of neocortical neurons in schizophrenia, autism spectrum disorder and intellectual disability are well documented. Dendritic spines are dynamic structures exhibiting Hebbian and homeostatic plasticity that triggers intracellular cascades involving glutamate receptors, calcium influx and remodeling of the F-actin network. The long-term potentiation (LTP)-induced insertion of postsynaptic glutamate receptors is associated with the enlargement of spine heads and long-term depression (LTD) with spine shrinkage. Using a murine model of ADHD, a delay in dendritic spines' maturation in CA1 hippocampal neurons correlated with impaired working memory and hippocampal LTP has recently reported. The aim of this review is to summarize recent evidence that has emerged from studies focused on the neuroanatomical and genetic features found in ADHD patients as well as reports from animal models describing the molecular structure and remodeling of dendritic spines.
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Affiliation(s)
- Gonzalo Ugarte
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
| | - Ricardo Piña
- Department of Biology, Faculty of Sciences, Metropolitan University of Education Sciences, Santiago 7760197, Chile;
- Department of Human Sciences, Faculty of Human Science, Bernardo O’Higgins University, Santiago 8370854, Chile
| | - Darwin Contreras
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
| | - Felipe Godoy
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
| | - David Rubio
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
| | - Carlos Rozas
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
| | - Marc Zeise
- School of Psychology, Faculty of Humanities, University of Santiago of Chile, Santiago 9170022, Chile;
| | - Rodrigo Vidal
- Laboratory of Genomics, Molecular Ecology and Evolutionary Studies, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile;
| | - Jorge Escobar
- Institute of Chemistry, Pontifical Catholic University of Valparaíso, Valparaíso 2340000, Chile
| | - Bernardo Morales
- Laboratory of Neuroscience, Department of Biology, Faculty of Chemistry and Biology, University of Santiago of Chile, Santiago 9170022, Chile; (G.U.); (D.C.); (F.G.); (D.R.); (C.R.)
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23
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Eggl MF, Chater TE, Petkovic J, Goda Y, Tchumatchenko T. Linking spontaneous and stimulated spine dynamics. Commun Biol 2023; 6:930. [PMID: 37696988 PMCID: PMC10495434 DOI: 10.1038/s42003-023-05303-1] [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: 05/19/2023] [Accepted: 08/29/2023] [Indexed: 09/13/2023] Open
Abstract
Our brains continuously acquire and store memories through synaptic plasticity. However, spontaneous synaptic changes can also occur and pose a challenge for maintaining stable memories. Despite fluctuations in synapse size, recent studies have shown that key population-level synaptic properties remain stable over time. This raises the question of how local synaptic plasticity affects the global population-level synaptic size distribution and whether individual synapses undergoing plasticity escape the stable distribution to encode specific memories. To address this question, we (i) studied spontaneously evolving spines and (ii) induced synaptic potentiation at selected sites while observing the spine distribution pre- and post-stimulation. We designed a stochastic model to describe how the current size of a synapse affects its future size under baseline and stimulation conditions and how these local effects give rise to population-level synaptic shifts. Our study offers insights into how seemingly spontaneous synaptic fluctuations and local plasticity both contribute to population-level synaptic dynamics.
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Affiliation(s)
- Maximilian F Eggl
- University of Mainz Medical Center, Anselm-Franz-von-Bentzel-Weg 3, 55128, Mainz, Germany
| | - Thomas E Chater
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan
| | - Janko Petkovic
- University of Mainz Medical Center, Anselm-Franz-von-Bentzel-Weg 3, 55128, Mainz, Germany
| | - Yukiko Goda
- Laboratory for Synaptic Plasticity and Connectivity, RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
- Synapse Biology Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Kunigami-gun, Okinawa, Japan
| | - Tatjana Tchumatchenko
- University of Mainz Medical Center, Anselm-Franz-von-Bentzel-Weg 3, 55128, Mainz, Germany.
- Institute of Experimental Epileptology and Cognition Research, University of Bonn Medical Center, Venusberg-Campus 1, 53127, Bonn, Germany.
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24
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Zhang C, Wang J, Wang W. Wnt signaling in synaptogenesis of Alzheimer's disease. IBRAIN 2023; 9:316-325. [PMID: 37786762 PMCID: PMC10527795 DOI: 10.1002/ibra.12130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 10/04/2023]
Abstract
Alzheimer's disease (AD), recognized as the leading cause of dementia, occupies a prominent position on the list of significant neurodegenerative disorders, representing a significant global health concern with far-reaching implications at both individual and societal levels. The primary symptom of Alzheimer's disease is a decrease in synaptic potency along with synaptic connection loss. Synapses, which act as important linkages between neuronal units within the cerebral region, are critical in signal transduction processes essential to orchestrating cognitive tasks. Synaptic connections act as critical interconnections between neuronal cells inside the cerebral environment, facilitating critical signal transduction processes required for cognitive functions. The confluence of axonal and dendritic filopodial extensions culminates in the creation of intercellular connections, coordinated by various signals and molecular mechanisms. The progression of synaptic maturation and plasticity is a critical determinant in maintaining mental well-being, and abnormalities in these processes have been linked to the development of neurodegenerative diseases. Wnt signaling pathways are important to the orchestration of synapse development. This review examines the complicated interplay between Wnt signaling and dendritic filopodia, including an examination of the regulatory complexities and molecular machinations involved in synaptogenesis progression. Then, these findings are contextualized within the context of AD pathology, allowing for the consideration of prospective therapeutic approaches based on the findings and development of novel avenues for future scientific research.
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Affiliation(s)
| | - Joy Wang
- Winchester High SchoolWinchesterMassachusettsUSA
| | - Wen‐Yuan Wang
- Interdisciplinary Research Center on Biology and ChemistryShanghai Institute of Organic Chemistry, Chinese Academy of ScienceShanghaiChina
- Huashan HospitalFudan UniversityShanghaiChina
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25
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Voglewede MM, Ozsen EN, Ivak N, Bernabucci M, Sun M, Pang ZP, Zhang H. Loss of the polarity protein Par3 promotes dendritic spine neoteny and enhances learning and memory. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.30.555530. [PMID: 37693426 PMCID: PMC10491238 DOI: 10.1101/2023.08.30.555530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The Par3 polarity protein is critical for subcellular compartmentalization in different developmental processes. Variants of PARD3 , which encodes PAR3, are associated with intelligence and neurodevelopmental disorders. However, the role of Par3 in glutamatergic synapse formation and cognitive functions in vivo remains unknown. Here, we show that forebrain conditional knockout of Par3 leads to an increase in long, thin dendritic spines without significantly impacting mushroom spines in vivo . In addition, we observed a decrease in the amplitude of miniature excitatory postsynaptic currents. Surprisingly, loss of Par3 in vivo enhances hippocampal- dependent spatial learning. Phosphoproteomic analysis revealed proteins regulating cytoskeletal dynamics are significantly dysregulated downstream of Par3. Mechanistically, we found Par3 deletion causes increased activation of the Rac1 pathway. Together, our data reveal an unexpected role for Par3 as a molecular gatekeeper in regulating the pool of immature dendritic spines, a rate-limiting step of learning and memory, through modulating Rac1 activation in vivo .
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26
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Guo X, Lei M, Zhao J, Wu M, Ren Z, Yang X, Ouyang C, Liu X, Liu C, Chen Q. Tirzepatide ameliorates spatial learning and memory impairment through modulation of aberrant insulin resistance and inflammation response in diabetic rats. Front Pharmacol 2023; 14:1146960. [PMID: 37701028 PMCID: PMC10493299 DOI: 10.3389/fphar.2023.1146960] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 08/14/2023] [Indexed: 09/14/2023] Open
Abstract
Background: One of the typical symptoms of diabetes mellitus patients was memory impairment, which was followed by gradual cognitive deterioration and for which there is no efficient treatment. The anti-diabetic incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were demonstrated to have highly neuroprotective benefits in animal models of AD. We wanted to find out how the GLP-1/GIP dual agonist tirzepatide affected diabetes's impairment of spatial learning memory. Methods: High fat diet and streptozotocin injection-induced diabetic rats were injected intraperitoneally with Tirzepatide (1.35 mg/kg) once a week. The protective effects were assessed using the Morris water maze test, immunofluorescence, and Western blot analysis. Golgi staining was adopted for quantified dendritic spines. Results: Tirzepatide significantly improved impaired glucose tolerance, fasting blood glucose level, and insulin level in diabetic rats. Then, tirzepatide dramatically alleviated spatial learning and memory impairment, inhibited Aβ accumulation, prevented structural damage, boosted the synthesis of synaptic proteins and increased dendritic spines formation in diabetic hippocampus. Furthermore, some aberrant changes in signal molecules concerning inflammation signaling pathways were normalized after tirzepatide treatment in diabetic rats. Finally, PI3K/Akt/GSK3β signaling pathway was restored by tirzepatide. Conclusion: Tirzepatide obviously exerts a protective effect against spatial learning and memory impairment, potentially through regulating abnormal insulin resistance and inflammatory responses.
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Affiliation(s)
- Xiying Guo
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Min Lei
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Jiangyan Zhao
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Min Wu
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Zhanhong Ren
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Xiaosong Yang
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Changhan Ouyang
- Pharmacy College, Xianning Medical College, Hubei University of Science and Technology, Xianning, China
| | - Xiufen Liu
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Chao Liu
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
| | - Qingjie Chen
- Hubei Key Laboratory of Diabetes and Angiopathy, Xianning Medical College, Medical Research Institute, Hubei University of Science and Technology, Xianning, China
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27
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Whiddon ZD, Marshall JB, Alston DC, McGee AW, Krimm RF. Rapid structural remodeling of peripheral taste neurons is independent of taste cell turnover. PLoS Biol 2023; 21:e3002271. [PMID: 37651406 PMCID: PMC10499261 DOI: 10.1371/journal.pbio.3002271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 09/13/2023] [Accepted: 07/22/2023] [Indexed: 09/02/2023] Open
Abstract
Taste bud cells are constantly replaced in taste buds as old cells die and new cells migrate into the bud. The perception of taste relies on new taste bud cells integrating with existing neural circuitry, yet how these new cells connect with a taste ganglion neuron is unknown. Do taste ganglion neurons remodel to accommodate taste bud cell renewal? If so, how much of the structure of taste axons is fixed and how much remodels? Here, we measured the motility and branching of individual taste arbors (the portion of the axon innervating taste buds) in mice over time with two-photon in vivo microscopy. Terminal branches of taste arbors continuously and rapidly remodel within the taste bud. This remodeling is faster than predicted by taste bud cell renewal, with terminal branches added and lost concurrently. Surprisingly, blocking entry of new taste bud cells with chemotherapeutic agents revealed that remodeling of the terminal branches on taste arbors does not rely on the renewal of taste bud cells. Although terminal branch remodeling was fast and intrinsically controlled, no new arbors were added to taste buds, and few were lost over 100 days. Taste ganglion neurons maintain a stable number of arbors that are each capable of high-speed remodeling. We propose that terminal branch plasticity permits arbors to locate new taste bud cells, while stability of arbor number supports constancy in the degree of connectivity and function for each neuron over time.
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Affiliation(s)
- Zachary D. Whiddon
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Jaleia B. Marshall
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - David C. Alston
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Aaron W. McGee
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
| | - Robin F. Krimm
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky, United States of America
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28
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Krüssel S, Deb I, Son S, Ewall G, Chang M, Lee HK, do Heo W, Kwon HB. Exuberant de novo dendritic spine growth in mature neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.21.550095. [PMID: 37546796 PMCID: PMC10401948 DOI: 10.1101/2023.07.21.550095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Dendritic spines are structural correlates of excitatory synapses maintaining stable synaptic communications. However, this strong spine-synapse relationship was mainly characterized in excitatory pyramidal neurons (PyNs), raising a possibility that inferring synaptic density from dendritic spine number may not be universally applied to all neuronal types. Here we found that the ectopic expression of H-Ras increased dendritic spine numbers regardless of cortical cell types such as layer 2/3 pyramidal neurons (PyNs), parvalbumin (PV)- and vasoactive intestinal peptide (VIP)-positive interneurons (INs) in the primary motor cortex (M1). The probability of detecting dendritic spines was positively correlated with the magnitude of H-Ras activity, suggesting elevated local H-Ras activity is involved in the process of dendritic spine formation. H-Ras overexpression caused high spine turnover rate via adding more spines rather than eliminating them. Two-photon photolysis of glutamate triggered de novo dendritic spine formation in mature neurons, suggesting H-Ras induced spine formation is not restricted to the early development. In PyNs and PV-INs, but not VIP-INs, we observed a shift in average spine neck length towards longer filopodia-like phenotypes. The portion of dendritic spines lacking key excitatory synaptic proteins were significantly increased in H-Ras transfected neurons, suggesting that these increased spines have other distinct functions. High spine density caused by H-Ras did not result in change in the frequency or the amplitude of miniature excitatory postsynaptic currents (mEPSCs). Thus, our results propose that dendritic spines possess more multifaceted functions beyond the morphological proxy of excitatory synapse.
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Affiliation(s)
- Sarah Krüssel
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ishana Deb
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seungkyu Son
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Gabrielle Ewall
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Minhyeok Chang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hey-Kyoung Lee
- Solomon H. Snyder Department of Neuroscience, Zanvyl-Krieger Mind/Brain Institute, Johns Hopkins School of Medicine, Baltimore, MD, United States
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States
| | - Won do Heo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hyung-Bae Kwon
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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29
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Lobov SA, Berdnikova ES, Zharinov AI, Kurganov DP, Kazantsev VB. STDP-Driven Rewiring in Spiking Neural Networks under Stimulus-Induced and Spontaneous Activity. Biomimetics (Basel) 2023; 8:320. [PMID: 37504208 PMCID: PMC10807410 DOI: 10.3390/biomimetics8030320] [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: 06/22/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 07/29/2023] Open
Abstract
Mathematical and computer simulation of learning in living neural networks have typically focused on changes in the efficiency of synaptic connections represented by synaptic weights in the models. Synaptic plasticity is believed to be the cellular basis for learning and memory. In spiking neural networks composed of dynamical spiking units, a biologically relevant learning rule is based on the so-called spike-timing-dependent plasticity or STDP. However, experimental data suggest that synaptic plasticity is only a part of brain circuit plasticity, which also includes homeostatic and structural plasticity. A model of structural plasticity proposed in this study is based on the activity-dependent appearance and disappearance of synaptic connections. The results of the research indicate that such adaptive rewiring enables the consolidation of the effects of STDP in response to a local external stimulation of a neural network. Subsequently, a vector field approach is used to demonstrate the successive "recording" of spike paths in both functional connectome and synaptic connectome, and finally in the anatomical connectome of the network. Moreover, the findings suggest that the adaptive rewiring could stabilize network dynamics over time in the context of activity patterns' reproducibility. A universal measure of such reproducibility introduced in this article is based on similarity between time-consequent patterns of the special vector fields characterizing both functional and anatomical connectomes.
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Affiliation(s)
- Sergey A. Lobov
- Laboratory of Neurobiomorphic Technologies, The Moscow Institute of Physics and Technology, 117303 Moscow, Russia;
- Neurotechnology Department, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia; (E.S.B.); (A.I.Z.)
| | - Ekaterina S. Berdnikova
- Neurotechnology Department, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia; (E.S.B.); (A.I.Z.)
| | - Alexey I. Zharinov
- Neurotechnology Department, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia; (E.S.B.); (A.I.Z.)
| | - Dmitry P. Kurganov
- Laboratory of Neuromodeling, Samara State Medical University, 443079 Samara, Russia;
| | - Victor B. Kazantsev
- Laboratory of Neurobiomorphic Technologies, The Moscow Institute of Physics and Technology, 117303 Moscow, Russia;
- Neurotechnology Department, Lobachevsky State University of Nizhny Novgorod, 603022 Nizhny Novgorod, Russia; (E.S.B.); (A.I.Z.)
- Laboratory of Neuromodeling, Samara State Medical University, 443079 Samara, Russia;
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30
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Malakasis N, Chavlis S, Poirazi P. Synaptic turnover promotes efficient learning in bio-realistic spiking neural networks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541722. [PMID: 37292929 PMCID: PMC10245885 DOI: 10.1101/2023.05.22.541722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
While artificial machine learning systems achieve superhuman performance in specific tasks such as language processing, image and video recognition, they do so use extremely large datasets and huge amounts of power. On the other hand, the brain remains superior in several cognitively challenging tasks while operating with the energy of a small lightbulb. We use a biologically constrained spiking neural network model to explore how the neural tissue achieves such high efficiency and assess its learning capacity on discrimination tasks. We found that synaptic turnover, a form of structural plasticity, which is the ability of the brain to form and eliminate synapses continuously, increases both the speed and the performance of our network on all tasks tested. Moreover, it allows accurate learning using a smaller number of examples. Importantly, these improvements are most significant under conditions of resource scarcity, such as when the number of trainable parameters is halved and when the task difficulty is increased. Our findings provide new insights into the mechanisms that underlie efficient learning in the brain and can inspire the development of more efficient and flexible machine learning algorithms.
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Affiliation(s)
- Nikos Malakasis
- School of Medicine, University of Crete, Heraklion 70013, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece
| | - Spyridon Chavlis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece
| | - Panayiota Poirazi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion 70013, Greece
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31
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Zhao Z, Zhou Y, Liu B, He J, Zhao J, Cai Y, Fan J, Li X, Wang Z, Lu Z, Wu J, Qi H, Dai Q. Two-photon synthetic aperture microscopy for minimally invasive fast 3D imaging of native subcellular behaviors in deep tissue. Cell 2023; 186:2475-2491.e22. [PMID: 37178688 DOI: 10.1016/j.cell.2023.04.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/21/2023] [Accepted: 04/10/2023] [Indexed: 05/15/2023]
Abstract
Holistic understanding of physio-pathological processes requires noninvasive 3D imaging in deep tissue across multiple spatial and temporal scales to link diverse transient subcellular behaviors with long-term physiogenesis. Despite broad applications of two-photon microscopy (TPM), there remains an inevitable tradeoff among spatiotemporal resolution, imaging volumes, and durations due to the point-scanning scheme, accumulated phototoxicity, and optical aberrations. Here, we harnessed the concept of synthetic aperture radar in TPM to achieve aberration-corrected 3D imaging of subcellular dynamics at a millisecond scale for over 100,000 large volumes in deep tissue, with three orders of magnitude reduction in photobleaching. With its advantages, we identified direct intercellular communications through migrasome generation following traumatic brain injury, visualized the formation process of germinal center in the mouse lymph node, and characterized heterogeneous cellular states in the mouse visual cortex, opening up a horizon for intravital imaging to understand the organizations and functions of biological systems at a holistic level.
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Affiliation(s)
- Zhifeng Zhao
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China; Hangzhou Zhuoxi Institute of Brain and Intelligence, Hangzhou 311100, China
| | - Yiliang Zhou
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China; Hangzhou Zhuoxi Institute of Brain and Intelligence, Hangzhou 311100, China
| | - Bo Liu
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China; Laboratory of Dynamic Immunobiology, Institute for Immunology, Tsinghua University, Beijing 100084, China; Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jing He
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Jiayin Zhao
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518071, China
| | - Yeyi Cai
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Jingtao Fan
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China
| | - Xinyang Li
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; Hangzhou Zhuoxi Institute of Brain and Intelligence, Hangzhou 311100, China; Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518071, China
| | - Zilin Wang
- Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Department of Anesthesiology, the First Medical Center, Chinese PLA General Hospital, Beijing 100853, China
| | - Zhi Lu
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China; Hangzhou Zhuoxi Institute of Brain and Intelligence, Hangzhou 311100, China
| | - Jiamin Wu
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China.
| | - Hai Qi
- Tsinghua-Peking Center for Life Sciences, Beijing 100084, China; Laboratory of Dynamic Immunobiology, Institute for Immunology, Tsinghua University, Beijing 100084, China; Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory for Immunological Research on Chronic Diseases, Tsinghua University, Beijing 100084, China; Beijing Frontier Research Center for Biological Structure, Tsinghua University, Beijing 100084, China.
| | - Qionghai Dai
- Department of Automation, Tsinghua University, Beijing 100084, China; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing 100084, China; Beijing Key Laboratory of Multi-dimension & Multi-scale Computational Photography (MMCP), Tsinghua University, Beijing 100084, China; IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China.
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Pham AQ, Dore K. Novel approaches to increase synaptic resilience as potential treatments for Alzheimer's disease. Semin Cell Dev Biol 2023; 139:84-92. [PMID: 35370089 DOI: 10.1016/j.semcdb.2022.03.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 12/31/2022]
Abstract
A significant proportion of brains with Alzheimer's disease pathology are obtained from patients that were cognitively normal, suggesting that differences within the brains of these individuals made them resilient to the disease. Here, we describe recent approaches that specifically increase synaptic resilience, as loss of synapses is considered to be the first change in the brains of Alzheimer's patients. We start by discussing studies showing benefit from increased expression of neurotrophic factors and protective genes. Methods that effectively make dendritic spines stronger, specifically by acting through actin network proteins, scaffolding proteins and inhibition of phosphatases are described next. Importantly, the therapeutic strategies presented in this review tackle Alzheimer's disease not by targeting plaques and tangles, but instead by making synapses resilient to the pathology associated with Alzheimer's disease, which has tremendous potential.
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Affiliation(s)
- Andrew Q Pham
- Department of Neurosciences, Center for Neural Circuits and Behavior, UCSD, La Jolla 92093, United States
| | - Kim Dore
- Department of Neurosciences, Center for Neural Circuits and Behavior, UCSD, La Jolla 92093, United States.
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Qiao C, Liu Z, Qie S. The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery. Biomolecules 2023; 13:biom13030571. [PMID: 36979506 PMCID: PMC10046452 DOI: 10.3390/biom13030571] [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: 01/17/2023] [Revised: 02/23/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Stroke causes varying degrees of neurological deficits, leading to corresponding dysfunctions. There are different therapeutic principles for each stage of pathological development. Neuroprotection is the main treatment in the acute phase, and functional recovery becomes primary in the subacute and chronic phases. Neuroplasticity is considered the basis of functional restoration and neurological rehabilitation after stroke, including the remodeling of dendrites and dendritic spines, axonal sprouting, myelin regeneration, synapse shaping, and neurogenesis. Spatiotemporal development affects the spontaneous rewiring of neural circuits and brain networks. Microglia are resident immune cells in the brain that contribute to homeostasis under physiological conditions. Microglia are activated immediately after stroke, and phenotypic polarization changes and phagocytic function are crucial for regulating focal and global brain inflammation and neurological recovery. We have previously shown that the development of neuroplasticity is spatiotemporally consistent with microglial activation, suggesting that microglia may have a profound impact on neuroplasticity after stroke and may be a key therapeutic target for post-stroke rehabilitation. In this review, we explore the impact of neuroplasticity on post-stroke restoration as well as the functions and mechanisms of microglial activation, polarization, and phagocytosis. This is followed by a summary of microglia-targeted rehabilitative interventions that influence neuroplasticity and promote stroke recovery.
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Affiliation(s)
- Chenye Qiao
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing 100144, China
| | - Zongjian Liu
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing 100144, China
| | - Shuyan Qie
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing 100144, China
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34
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Gergin S, Kirazlı Ö, Boracı H, Yıldız SD, Yananlı HR, Şehirli ÜS. The effects of regular swimming exercise and melatonin on the neurons localized in the striatum of hemiparkinsonian rats. Anat Sci Int 2023; 98:204-219. [PMID: 36223003 DOI: 10.1007/s12565-022-00688-1] [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: 02/06/2022] [Accepted: 09/27/2022] [Indexed: 02/07/2023]
Abstract
Parkinson's disease is a progressive neurodegenerative movement disorder. We aimed to investigate the effects of regular swimming exercise and melatonin applied in the 6-Hydroxydopamine-induced Parkinson's disease rats by analysing dendritic spine of striatal neurons. Twenty-four male Wistar albino rats were used. 6-Hydroxydopamine unilaterally injected four (control, exercise, melatonin and exercise + melatonin) groups were included in the study. Tyrosine hydroxylase expression was detected by immunohistochemistry. Neurons and structures were identified from three-dimensional images by Neurolucida software. There was not any apparent difference for tyrosine hydroxylase positive neurons in the substantia nigra pars compacta and fibres in the striatum between the lesion sides of hemiparkinsonian groups. The treatment groups blocked the apomorphine-induced increase in rotations compared to the control group. In stepping test, the treatment groups prevented the loss of stepping in the contralateral side of hemiparkinsonian groups. The melatonin mostly had a positive effect on motor activity tests. In morphological analyses, the 6-Hydroxydopamine-induced lesion led to the reduction of the total dendritic length and number of branches. In the treatment groups, the reduction of the dendritic parameters was not observed. 6-Hydroxydopamine lesion led to a decrease in the total spine density, spine densities of thin and mushroom types. The exercise and melatonin treatments prevented the loss of spine density. The exercise treatment prevented the loss of spine density of mushroom type spines. The melatonin treatment blocked the loss of spine density of stubby type. In conclusion, these results provide evidence for effective additional protective therapeutic strategies for Parkinson's disease. In conclusion, results from the current study provide evidence for swimming exercise and melatonin as a promising candidate for effective additional protective strategies for PD.
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Affiliation(s)
- Sinem Gergin
- Department of Anatomy, Marmara University School of Medicine, Istanbul, Turkey.,, Istanbul, Turkey.,Marmara University Institute of Health Sciences, Istanbul, Turkey
| | - Özlem Kirazlı
- Department of Anatomy, Marmara University School of Medicine, Istanbul, Turkey.,Marmara University Institute of Health Sciences, Istanbul, Turkey
| | - Hatice Boracı
- Department of Anatomy, Marmara University School of Medicine, Istanbul, Turkey.,Marmara University Institute of Health Sciences, Istanbul, Turkey
| | - Sercan Doğukan Yıldız
- Department of Anatomy, Marmara University School of Medicine, Istanbul, Turkey.,Marmara University Institute of Health Sciences, Istanbul, Turkey.,Faculty of Dentistry, Department of Anatomy, Istanbul Kent University, Istanbul, Turkey
| | - Hasan Raci Yananlı
- Department of Medical Pharmacology, Marmara University School of Medicine, Istanbul, Turkey
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35
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Evano B, Sarde L, Tajbakhsh S. Temporal static and dynamic imaging of skeletal muscle in vivo. Exp Cell Res 2023; 424:113484. [PMID: 36693490 DOI: 10.1016/j.yexcr.2023.113484] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/13/2023] [Accepted: 01/15/2023] [Indexed: 01/22/2023]
Abstract
A major challenge in the study of living systems is understanding how tissues and organs are established, maintained during homeostasis, reconstituted following injury or deteriorated during disease. Most of the studies that interrogate in vivo cell biological properties of cell populations within tissues are obtained through static imaging approaches. However, in vertebrates, little is known about which, when, and how extracellular and intracellular signals are dynamically integrated to regulate cell behaviour and fates, due largely to technical challenges. Intravital imaging of cellular dynamics in mammalian models has exposed surprising properties that have been missed by conventional static imaging approaches. Here we highlight some selected examples of intravital imaging in mouse intestinal stem cells, hematopoietic stem cells, hair follicle stem cells, and neural stem cells in the brain, each of which have distinct features from an anatomical and niche-architecture perspective. Intravital imaging of mouse skeletal muscles is comparatively less advanced due to several technical constraints that will be discussed, yet this approach holds great promise as a complementary investigative method to validate findings obtained by static imaging, as well as a method for discovery.
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Affiliation(s)
- Brendan Evano
- Stem Cells and Development, Department of Developmental & Stem Cell Biology, Institut Pasteur, Université Paris Cité, Paris, 75015, France; CNRS UMR 3738, Institut Pasteur, Paris, 75015, France
| | - Liza Sarde
- Stem Cells and Development, Department of Developmental & Stem Cell Biology, Institut Pasteur, Université Paris Cité, Paris, 75015, France; CNRS UMR 3738, Institut Pasteur, Paris, 75015, France; Sorbonne Université, Complexité Du Vivant, F-75005, Paris, France
| | - Shahragim Tajbakhsh
- Stem Cells and Development, Department of Developmental & Stem Cell Biology, Institut Pasteur, Université Paris Cité, Paris, 75015, France; CNRS UMR 3738, Institut Pasteur, Paris, 75015, France.
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36
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Freire-Cobo C, Rothwell ES, Varghese M, Edwards M, Janssen WGM, Lacreuse A, Hof PR. Neuronal vulnerability to brain aging and neurodegeneration in cognitively impaired marmoset monkeys (Callithrix jacchus). Neurobiol Aging 2023; 123:49-62. [PMID: 36638681 PMCID: PMC9892246 DOI: 10.1016/j.neurobiolaging.2022.12.001] [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: 09/05/2022] [Revised: 12/01/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022]
Abstract
The investigation of neurobiological and neuropathological changes that affect synaptic integrity and function with aging is key to understanding why the aging brain is vulnerable to Alzheimer's disease. We investigated the cellular characteristics in the cerebral cortex of behaviorally characterized marmosets, based on their trajectories of cognitive learning as they transitioned to old age. We found increased astrogliosis, increased phagocytic activity of microglial cells and differences in resting and reactive microglial cell phenotypes in cognitively impaired compared to nonimpaired marmosets. Differences in amyloid beta deposition were not related to cognitive trajectory. However, we found age-related changes in density and morphology of dendritic spines in pyramidal neurons of layer 3 in the dorsolateral prefrontal cortex and the CA1 field of the hippocampus between cohorts. Overall, our data suggest that an accelerated aging process, accompanied by neurodegeneration, that takes place in cognitively impaired aged marmosets and affects the plasticity of dendritic spines in cortical areas involved in cognition and points to mechanisms of neuronal vulnerability to aging.
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Affiliation(s)
- Carmen Freire-Cobo
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Emily S Rothwell
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, MA, USA
| | - Merina Varghese
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mélise Edwards
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, MA, USA
| | - William G M Janssen
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Agnès Lacreuse
- Department of Psychological and Brain Sciences, University of Massachusetts, Amherst, MA, USA
| | - Patrick R Hof
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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37
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The times they are a-changin': a proposal on how brain flexibility goes beyond the obvious to include the concepts of "upward" and "downward" to neuroplasticity. Mol Psychiatry 2023; 28:977-992. [PMID: 36575306 PMCID: PMC10005965 DOI: 10.1038/s41380-022-01931-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/07/2022] [Accepted: 12/14/2022] [Indexed: 12/28/2022]
Abstract
Since the brain was found to be somehow flexible, plastic, researchers worldwide have been trying to comprehend its fundamentals to better understand the brain itself, make predictions, disentangle the neurobiology of brain diseases, and finally propose up-to-date treatments. Neuroplasticity is simple as a concept, but extremely complex when it comes to its mechanisms. This review aims to bring to light an aspect about neuroplasticity that is often not given enough attention as it should, the fact that the brain's ability to change would include its ability to disconnect synapses. So, neuronal shrinkage, decrease in spine density or dendritic complexity should be included within the concept of neuroplasticity as part of its mechanisms, not as an impairment of it. To that end, we extensively describe a variety of studies involving topics such as neurodevelopment, aging, stress, memory and homeostatic plasticity to highlight how the weakening and disconnection of synapses organically permeate the brain in so many ways as a good practice of its intrinsic physiology. Therefore, we propose to break down neuroplasticity into two sub-concepts, "upward neuroplasticity" for changes related to synaptic construction and "downward neuroplasticity" for changes related to synaptic deconstruction. With these sub-concepts, neuroplasticity could be better understood from a bigger landscape as a vector in which both directions could be taken for the brain to flexibly adapt to certain demands. Such a paradigm shift would allow a better understanding of the concept of neuroplasticity to avoid any data interpretation bias, once it makes clear that there is no morality with regard to the organic and physiological changes that involve dynamic biological systems as seen in the brain.
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Katsube S, Koganezawa N, Hanamura K, Cuthill KJ, Tarabykin V, Ambrozkiewicz MC, Kawabe H. The murine ortholog of Kaufman oculocerebrofacial syndrome gene Ube3b is crucial for the maintenance of the excitatory synapses in the young adult stage. Neurosci Lett 2023; 797:137059. [PMID: 36623761 DOI: 10.1016/j.neulet.2023.137059] [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: 09/07/2022] [Revised: 12/21/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023]
Abstract
Kaufman oculocerebrofacial syndrome (KOS) is an autosomal recessive developmental disorder. Inactivating mutations in UBE3B, an E3 ubiquitin ligase gene are causative for KOS. We have reported that towards postnatal week three, its murine ortholog, Ube3b, acts as a negative regulator of the number of dendritic spines. In this study, we investigated the role of Ube3b at the synapse in the young adult mice. With an improved estimation method, images from the hippocampal CA1 and CA2 regions acquired with 3D Stimulated Emission Depletion (3D-STED) microscopy were used to quantify the excitatory synapse numbers. In the young adult mice, the excitatory synapse density was decreased in brain-specific Ube3b conditional knockout mice as compared to the control. Our results indicate the novel role of Ube3b in the maintenance of synapse numbers in the young adult period.
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Affiliation(s)
- Saki Katsube
- Department of Pharmacology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan; Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | - Noriko Koganezawa
- Department of Pharmacology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
| | - Kenji Hanamura
- Department of Pharmacology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
| | - Katherine J Cuthill
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany
| | - Victor Tarabykin
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany; Institute of Neuroscience, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia; Research Institute of Medical Genetics, Tomsk National Research Medical Center of the Russian Academy of Sciences, Tomsk 634009, Russia
| | - Mateusz C Ambrozkiewicz
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Charitéplatz 1, 10117 Berlin, Germany
| | - Hiroshi Kawabe
- Department of Pharmacology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
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Steffen DM, Hanes CM, Mah KM, Valiño Ramos P, Bosch PJ, Hinz DC, Radley JJ, Burgess RW, Garrett AM, Weiner JA. A Unique Role for Protocadherin γC3 in Promoting Dendrite Arborization through an Axin1-Dependent Mechanism. J Neurosci 2023; 43:918-935. [PMID: 36604170 PMCID: PMC9908324 DOI: 10.1523/jneurosci.0729-22.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 11/30/2022] [Accepted: 12/24/2022] [Indexed: 01/06/2023] Open
Abstract
The establishment of a functional cerebral cortex depends on the proper execution of multiple developmental steps, culminating in dendritic and axonal outgrowth and the formation and maturation of synaptic connections. Dysregulation of these processes can result in improper neuronal connectivity, including that associated with various neurodevelopmental disorders. The γ-Protocadherins (γ-Pcdhs), a family of 22 distinct cell adhesion molecules that share a C-terminal cytoplasmic domain, are involved in multiple aspects of neurodevelopment including neuronal survival, dendrite arborization, and synapse development. The extent to which individual γ-Pcdh family members play unique versus common roles remains unclear. We demonstrated previously that the γ-Pcdh-C3 isoform (γC3), via its unique "variable" cytoplasmic domain (VCD), interacts in cultured cells with Axin1, a Wnt-pathway scaffold protein that regulates the differentiation and morphology of neurons. Here, we confirm that γC3 and Axin1 interact in the cortex in vivo and show that both male and female mice specifically lacking γC3 exhibit disrupted Axin1 localization to synaptic fractions, without obvious changes in dendritic spine density or morphology. However, both male and female γC3 knock-out mice exhibit severely decreased dendritic complexity of cortical pyramidal neurons that is not observed in mouse lines lacking several other γ-Pcdh isoforms. Combining knock-out with rescue constructs in cultured cortical neurons pooled from both male and female mice, we show that γC3 promotes dendritic arborization through an Axin1-dependent mechanism mediated through its VCD. Together, these data identify a novel mechanism through which γC3 uniquely regulates the formation of cortical circuitry.SIGNIFICANCE STATEMENT The complexity of a neuron's dendritic arbor is critical for its function. We showed previously that the γ-Protocadherin (γ-Pcdh) family of 22 cell adhesion molecules promotes arborization during development; it remained unclear whether individual family members played unique roles. Here, we show that one γ-Pcdh isoform, γC3, interacts in the brain with Axin1, a scaffolding protein known to influence dendrite development. A CRISPR/Cas9-generated mutant mouse line lacking γC3 (but not lines lacking other γ-Pcdhs) exhibits severely reduced dendritic complexity of cerebral cortex neurons. Using cultured γC3 knock-out neurons and a variety of rescue constructs, we confirm that the γC3 cytoplasmic domain promotes arborization through an Axin1-dependent mechanism. Thus, γ-Pcdh isoforms are not interchangeable, but rather can play unique neurodevelopmental roles.
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Affiliation(s)
- David M Steffen
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
| | - Camille M Hanes
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
| | - Kar Men Mah
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
| | - Paula Valiño Ramos
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
| | - Peter J Bosch
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
| | - Dalton C Hinz
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Psychological and Brain Sciences, Program in Neuroscience, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Jason J Radley
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Psychological and Brain Sciences, Program in Neuroscience, Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | | | - Andrew M Garrett
- Department of Pharmacology and Department of Ophthalmology, Visual, and Anatomical Sciences, Wayne State University, Detroit, Michigan 48202
| | - Joshua A Weiner
- Iowa Neuroscience Institute, The University of Iowa, Iowa City, Iowa 52242
- Department of Biology, The University of Iowa, Iowa City, Iowa 52242
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Day-Cooney J, Dalangin R, Zhong H, Mao T. Genetically encoded fluorescent sensors for imaging neuronal dynamics in vivo. J Neurochem 2023; 164:284-308. [PMID: 35285522 DOI: 10.1111/jnc.15608] [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: 11/29/2021] [Revised: 02/14/2022] [Accepted: 02/25/2022] [Indexed: 11/29/2022]
Abstract
The brain relies on many forms of dynamic activities in individual neurons, from synaptic transmission to electrical activity and intracellular signaling events. Monitoring these neuronal activities with high spatiotemporal resolution in the context of animal behavior is a necessary step to achieve a mechanistic understanding of brain function. With the rapid development and dissemination of highly optimized genetically encoded fluorescent sensors, a growing number of brain activities can now be visualized in vivo. To date, cellular calcium imaging, which has been largely used as a proxy for electrical activity, has become a mainstay in systems neuroscience. While challenges remain, voltage imaging of neural populations is now possible. In addition, it is becoming increasingly practical to image over half a dozen neurotransmitters, as well as certain intracellular signaling and metabolic activities. These new capabilities enable neuroscientists to test previously unattainable hypotheses and questions. This review summarizes recent progress in the development and delivery of genetically encoded fluorescent sensors, and highlights example applications in the context of in vivo imaging.
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Affiliation(s)
- Julian Day-Cooney
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Rochelin Dalangin
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, USA
| | - Haining Zhong
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Tianyi Mao
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
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Kisner A, Polter AM. Maturation of glutamatergic transmission onto dorsal raphe serotonergic neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.19.524776. [PMID: 36711665 PMCID: PMC9882295 DOI: 10.1101/2023.01.19.524776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Serotonergic neurons in the dorsal raphe nucleus (DRN) play important roles early in postnatal development in the maturation and modulation of higher order emotional, sensory, and cognitive circuitry. This unique position makes these cells a substrate by which early experience can be wired into brain. In this study, we have investigated the maturation of synapses onto dorsal raphe serotonergic neurons in typically developing male and female mice using whole-cell patch-clamp recordings in ex vivo brain slices. We show that while inhibition of these neurons is relatively stable across development, glutamatergic synapses greatly increase in strength between P6 and P21-23. In contrast to forebrain regions, where the components making up glutamatergic synapses are dynamic across early life, we find that the makeup of these synapses onto DRN serotonergic neurons is largely stable after P15. DRN excitatory synapses maintain a very high ratio of AMPA to NMDA receptors and a rectifying component of the AMPA response throughout the lifespan. Overall, these findings reveal that the development of serotonergic neurons is marked by a significant refinement of glutamatergic synapses during the first 3 postnatal weeks. This suggests this time as a sensitive period of heightened plasticity for integration of information from upstream brain areas and that genetic and environmental insults during this period could lead to alterations in serotonergic output, impacting both the development of forebrain circuits and lifelong neuromodulatory actions.
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Affiliation(s)
- Alexandre Kisner
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037
- Current address: Department of Neuroscience, American University, Washington DC 20016
| | - Abigail M. Polter
- Department of Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037
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42
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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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KASAI H. Unraveling the mysteries of dendritic spine dynamics: Five key principles shaping memory and cognition. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2023; 99:254-305. [PMID: 37821392 PMCID: PMC10749395 DOI: 10.2183/pjab.99.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/11/2023] [Indexed: 10/13/2023]
Abstract
Recent research extends our understanding of brain processes beyond just action potentials and chemical transmissions within neural circuits, emphasizing the mechanical forces generated by excitatory synapses on dendritic spines to modulate presynaptic function. From in vivo and in vitro studies, we outline five central principles of synaptic mechanics in brain function: P1: Stability - Underpinning the integral relationship between the structure and function of the spine synapses. P2: Extrinsic dynamics - Highlighting synapse-selective structural plasticity which plays a crucial role in Hebbian associative learning, distinct from pathway-selective long-term potentiation (LTP) and depression (LTD). P3: Neuromodulation - Analyzing the role of G-protein-coupled receptors, particularly dopamine receptors, in time-sensitive modulation of associative learning frameworks such as Pavlovian classical conditioning and Thorndike's reinforcement learning (RL). P4: Instability - Addressing the intrinsic dynamics crucial to memory management during continual learning, spotlighting their role in "spine dysgenesis" associated with mental disorders. P5: Mechanics - Exploring how synaptic mechanics influence both sides of synapses to establish structural traces of short- and long-term memory, thereby aiding the integration of mental functions. We also delve into the historical background and foresee impending challenges.
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Affiliation(s)
- Haruo KASAI
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Heck N, Santos MD. Dendritic Spines in Learning and Memory: From First Discoveries to Current Insights. ADVANCES IN NEUROBIOLOGY 2023; 34:311-348. [PMID: 37962799 DOI: 10.1007/978-3-031-36159-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The central nervous system is composed of neural ensembles, and their activity patterns are neural correlates of cognitive functions. Those ensembles are networks of neurons connected to each other by synapses. Most neurons integrate synaptic signal through a remarkable subcellular structure called spine. Dendritic spines are protrusions whose diverse shapes make them appear as a specific neuronal compartment, and they have been the focus of studies for more than a century. Soon after their first description by Ramón y Cajal, it has been hypothesized that spine morphological changes could modify neuronal connectivity and sustain cognitive abilities. Later studies demonstrated that changes in spine density and morphology occurred in experience-dependent plasticity during development, and in clinical cases of mental retardation. This gave ground for the assumption that dendritic spines are the particular locus of cerebral plasticity. With the discovery of synaptic long-term potentiation, a research program emerged with the aim to establish whether dendritic spine plasticity could explain learning and memory. The development of live imaging methods revealed on the one hand that dendritic spine remodeling is compatible with learning process and, on the other hand, that their long-term stability is compatible with lifelong memories. Furthermore, the study of the mechanisms of spine growth and maintenance shed new light on the rules of plasticity. In behavioral paradigms of memory, spine formation or elimination and morphological changes were found to correlate with learning. In a last critical step, recent experiments have provided evidence that dendritic spines play a causal role in learning and memory.
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Affiliation(s)
- Nicolas Heck
- Laboratory Neurosciences Paris Seine, Sorbonne Université, Paris, France.
| | - Marc Dos Santos
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Tiberi A, Carucci NM, Testa G, Rizzi C, Pacifico P, Borgonovo G, Arisi I, D’Onofrio M, Brandi R, Gan WB, Capsoni S, Cattaneo A. Reduced levels of NGF shift astrocytes toward a neurotoxic phenotype. Front Cell Dev Biol 2023; 11:1165125. [PMID: 37143894 PMCID: PMC10151754 DOI: 10.3389/fcell.2023.1165125] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 03/16/2023] [Indexed: 05/06/2023] Open
Abstract
Nerve growth factor (NGF) is critical for neuronal physiology during development and adulthood. Despite the well-recognized effect of NGF on neurons, less is known about whether NGF can actually affect other cell types in the central nervous system (CNS). In this work, we show that astrocytes are susceptible to changes in ambient levels of NGF. First, we observe that interfering with NGF signaling in vivo via the constitutive expression of an antiNGF antibody induces astrocytic atrophy. A similar asthenic phenotype is encountered in an uncleavable proNGF transgenic mouse model (TgproNGF#72), effectively increasing the brain proNGF levels. To examine whether this effect on astrocytes is cell-autonomous, we cultured wild-type primary astrocytes in the presence of antiNGF antibodies, uncovering that a short incubation period is sufficient to potently and rapidly trigger calcium oscillations. Acute induction of calcium oscillations by antiNGF antibodies is followed by progressive morphological changes similar to those observed in antiNGF AD11 mice. Conversely, incubation with mature NGF has no effect on either calcium activity nor on astrocytic morphology. At longer timescales, transcriptomic analysis revealed that NGF-deprived astrocytes acquire a proinflammatory profile. In particular, antiNGF-treated astrocytes show upregulation of neurotoxic transcripts and downregulation of neuroprotective mRNAs. Consistent with that data, culturing wild-type neurons in the presence of NGF-deprived astrocytes leads to neuronal cell death. Finally, we report that in both awake and anesthetized mice, astrocytes in layer I of the motor cortex respond with an increase in calcium activity to acute NGF inhibition using either NGF-neutralizing antibodies or a TrkA-Fc NGF scavenger. Moreover, in vivo calcium imaging in the cortex of the 5xFAD neurodegeneration mouse model shows an increased level of spontaneous calcium activity in astrocytes, which is significantly reduced after acute administration of NGF. In conclusion, we unveil a novel neurotoxic mechanism driven by astrocytes, triggered by their sensing and reacting to changes in the levels of ambient NGF.
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Affiliation(s)
- Alexia Tiberi
- BIO@SNS, Scuola Normale Superiore, Pisa, Italy
- Skirball Institute of Biomolecular Medicine, Langone Medical Center, New York University, New York, NY, United States
| | | | | | | | | | | | - Ivan Arisi
- European Brain Research Institute - Fondazione Rita Levi-Montalcini, Rome, Italy
| | - Mara D’Onofrio
- European Brain Research Institute - Fondazione Rita Levi-Montalcini, Rome, Italy
| | - Rossella Brandi
- European Brain Research Institute - Fondazione Rita Levi-Montalcini, Rome, Italy
| | - Wen-Biao Gan
- Skirball Institute of Biomolecular Medicine, Langone Medical Center, New York University, New York, NY, United States
- Shenzhen Bay Laboratory, Shenzhen, China
| | - Simona Capsoni
- BIO@SNS, Scuola Normale Superiore, Pisa, Italy
- Institute of Physiology, Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
| | - Antonino Cattaneo
- BIO@SNS, Scuola Normale Superiore, Pisa, Italy
- European Brain Research Institute - Fondazione Rita Levi-Montalcini, Rome, Italy
- *Correspondence: Antonino Cattaneo,
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46
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Wouterlood FG. Techniques to Render Dendritic Spines Visible in the Microscope. ADVANCES IN NEUROBIOLOGY 2023; 34:69-102. [PMID: 37962794 DOI: 10.1007/978-3-031-36159-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
A tiny detail visible on certain neurons at the limit of resolution in light microscopy went in 130 years of neuroscience research through a dazzling career from suspicious staining artifact to what we recognize today as a complex postsynaptic molecular machine: the dendritic spine.This chapter deals with techniques to make spines visible. The original technique, Golgi silver staining, is still being used today. Electron microscopy and automated field ion beam scanning electron microscopy are ultrahigh resolution techniques, albeit specialized. Other methods are intracellular injection, uptake of dyes, and recently the exploitation of genetically modified animals in which certain neurons express fluorescent protein in all their processes, including the nooks and crannies of their dendritic spines.
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Affiliation(s)
- Floris G Wouterlood
- Department of Anatomy & Neurosciences, Amsterdam UMC, Amsterdam, The Netherlands
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47
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Petanjek Z, Banovac I, Sedmak D, Hladnik A. Dendritic Spines: Synaptogenesis and Synaptic Pruning for the Developmental Organization of Brain Circuits. ADVANCES IN NEUROBIOLOGY 2023; 34:143-221. [PMID: 37962796 DOI: 10.1007/978-3-031-36159-3_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Synaptic overproduction and elimination is a regular developmental event in the mammalian brain. In the cerebral cortex, synaptic overproduction is almost exclusively correlated with glutamatergic synapses located on dendritic spines. Therefore, analysis of changes in spine density on different parts of the dendritic tree in identified classes of principal neurons could provide insight into developmental reorganization of specific microcircuits.The activity-dependent stabilization and selective elimination of the initially overproduced synapses is a major mechanism for generating diversity of neural connections beyond their genetic determination. The largest number of overproduced synapses was found in the monkey and human cerebral cortex. The highest (exceeding adult values by two- to threefold) and most protracted overproduction (up to third decade of life) was described for associative layer IIIC pyramidal neurons in the human dorsolateral prefrontal cortex.Therefore, the highest proportion and extraordinarily extended phase of synaptic spine overproduction is a hallmark of neural circuitry in human higher-order associative areas. This indicates that microcircuits processing the most complex human cognitive functions have the highest level of developmental plasticity. This finding is the backbone for understanding the effect of environmental impact on the development of the most complex, human-specific cognitive and emotional capacities, and on the late onset of human-specific neuropsychiatric disorders, such as autism and schizophrenia.
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Affiliation(s)
- Zdravko Petanjek
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia.
| | - Ivan Banovac
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Dora Sedmak
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Ana Hladnik
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
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48
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Bulovaite E, Qiu Z, Kratschke M, Zgraj A, Fricker DG, Tuck EJ, Gokhale R, Koniaris B, Jami SA, Merino-Serrais P, Husi E, Mendive-Tapia L, Vendrell M, O'Dell TJ, DeFelipe J, Komiyama NH, Holtmaat A, Fransén E, Grant SGN. A brain atlas of synapse protein lifetime across the mouse lifespan. Neuron 2022; 110:4057-4073.e8. [PMID: 36202095 PMCID: PMC9789179 DOI: 10.1016/j.neuron.2022.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 07/01/2022] [Accepted: 09/07/2022] [Indexed: 11/12/2022]
Abstract
The lifetime of proteins in synapses is important for their signaling, maintenance, and remodeling, and for memory duration. We quantified the lifetime of endogenous PSD95, an abundant postsynaptic protein in excitatory synapses, at single-synapse resolution across the mouse brain and lifespan, generating the Protein Lifetime Synaptome Atlas. Excitatory synapses have a wide range of PSD95 lifetimes extending from hours to several months, with distinct spatial distributions in dendrites, neurons, and brain regions. Synapses with short protein lifetimes are enriched in young animals and in brain regions controlling innate behaviors, whereas synapses with long protein lifetimes accumulate during development, are enriched in the cortex and CA1 where memories are stored, and are preferentially preserved in old age. Synapse protein lifetime increases throughout the brain in a mouse model of autism and schizophrenia. Protein lifetime adds a further layer to synapse diversity and enriches prevailing concepts in brain development, aging, and disease.
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Affiliation(s)
- Edita Bulovaite
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Zhen Qiu
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Maximilian Kratschke
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Adrianna Zgraj
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - David G Fricker
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Eleanor J Tuck
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Ragini Gokhale
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Babis Koniaris
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; School of Computing, Edinburgh Napier University, Edinburgh EH10 5DT, UK
| | - Shekib A Jami
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Paula Merino-Serrais
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, UPM, 28223 Madrid, Spain; Instituto Cajal, CSIC, 28002 Madrid, Spain
| | - Elodie Husi
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Lorena Mendive-Tapia
- Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Marc Vendrell
- Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Thomas J O'Dell
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Integrative Center for Learning and Memory, Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Javier DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, UPM, 28223 Madrid, Spain; Instituto Cajal, CSIC, 28002 Madrid, Spain
| | - Noboru H Komiyama
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK; The Patrick Wild Centre for Research into Autism, Fragile X Syndrome & Intellectual Disabilities, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK; Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Anthony Holtmaat
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Erik Fransén
- Department of Computational Science and Technology, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, 10044 Stockholm, Sweden; Science for Life Laboratory, KTH Royal Institute of Technology, 171 65 Solna, Sweden
| | - Seth G N Grant
- Genes to Cognition Program, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh EH16 4SB, UK; Simons Initiative for the Developing Brain (SIDB), Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK.
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49
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Ciganok-Hückels N, Jehasse K, Kricsfalussy-Hrabár L, Ritter M, Rüland T, Kampa BM. Postnatal development of electrophysiological and morphological properties in layer 2/3 and layer 5 pyramidal neurons in the mouse primary visual cortex. Cereb Cortex 2022; 33:5875-5884. [PMID: 36453454 PMCID: PMC10183751 DOI: 10.1093/cercor/bhac467] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/04/2022] [Accepted: 11/05/2022] [Indexed: 12/03/2022] Open
Abstract
Abstract
Eye-opening is a critical point for laminar maturation of pyramidal neurons (PNs) in primary visual cortex. Knowing both the intrinsic properties and morphology of PNs from the visual cortex during development is crucial to contextualize the integration of visual inputs at different age stages. Few studies have reported changes in intrinsic excitability in these neurons but were restricted to only one layer or one stage of cortical development. Here, we used in vitro whole-cell patch-clamp to investigate the developmental impact on electrophysiological properties of layer 2/3 and layer 5 PNs in mouse visual cortex. Additionally, we evaluated the morphological changes before and after eye-opening and compared these in adult mice. Overall, we found a decrease in intrinsic excitability in both layers after eye-opening which remained stable between juvenile and adult mice. The basal dendritic length increased in layer 5 neurons, whereas spine density increased in layer 2/3 neurons after eye-opening. These data show increased number of synapses after onset of sensory input paralleled with a reduced excitability, presumably as homeostatic mechanism. Altogether, we provide a database of the properties of PNs in mouse visual cortex by considering the layer- and time-specific changes of these neurons during sensory development.
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Affiliation(s)
- Natalja Ciganok-Hückels
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
| | - Kevin Jehasse
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
| | | | - Mira Ritter
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
| | - Thomas Rüland
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
- Institute for Biological Information Processing (IBI-1), Forschungszentrum Jülich , 52428 Jülich , Germany
| | - Björn M Kampa
- Systems Neurophysiology, Institute of Zoology, RWTH Aachen University , 52074 Aachen , Germany
- Research Training Group 2416 MultiSenses-MultiScales, RWTH Aachen University , 52074 Aachen , Germany
- JARA BRAIN, Institute of Neuroscience and Medicine (INM-10), Forschungszentrum Jülich , 52428 Jülich , Germany
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50
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Vardalaki D, Chung K, Harnett MT. Filopodia are a structural substrate for silent synapses in adult neocortex. Nature 2022; 612:323-327. [PMID: 36450984 DOI: 10.1038/s41586-022-05483-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/25/2022] [Indexed: 12/05/2022]
Abstract
Newly generated excitatory synapses in the mammalian cortex lack sufficient AMPA-type glutamate receptors to mediate neurotransmission, resulting in functionally silent synapses that require activity-dependent plasticity to mature. Silent synapses are abundant in early development, during which they mediate circuit formation and refinement, but they are thought to be scarce in adulthood1. However, adults retain a capacity for neural plasticity and flexible learning that suggests that the formation of new connections is still prevalent. Here we used super-resolution protein imaging to visualize synaptic proteins at 2,234 synapses from layer 5 pyramidal neurons in the primary visual cortex of adult mice. Unexpectedly, about 25% of these synapses lack AMPA receptors. These putative silent synapses were located at the tips of thin dendritic protrusions, known as filopodia, which were more abundant by an order of magnitude than previously believed (comprising about 30% of all dendritic protrusions). Physiological experiments revealed that filopodia do indeed lack AMPA-receptor-mediated transmission, but they exhibit NMDA-receptor-mediated synaptic transmission. We further showed that functionally silent synapses on filopodia can be unsilenced through Hebbian plasticity, recruiting new active connections into a neuron's input matrix. These results challenge the model that functional connectivity is largely fixed in the adult cortex and demonstrate a new mechanism for flexible control of synaptic wiring that expands the learning capabilities of the mature brain.
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Affiliation(s)
- Dimitra Vardalaki
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA.,Department of Brain & Cognitive Sciences, MIT, Cambridge, MA, USA
| | - Kwanghun Chung
- Department of Brain & Cognitive Sciences, MIT, Cambridge, MA, USA.,Picower Institute for Learning and Memory, MIT, Cambridge, MA, USA.,Institute for Medical Engineering and Science, MIT, Cambridge, MA, USA.,Department of Chemical Engineering, MIT, Cambridge, MA, USA.,Broad Institute of Harvard University and MIT, Cambridge, MA, USA
| | - Mark T Harnett
- McGovern Institute for Brain Research, MIT, Cambridge, MA, USA. .,Department of Brain & Cognitive Sciences, MIT, Cambridge, MA, USA.
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