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Hinova-Palova D, Landzhov B, Edelstein L, Fakih K, Alexandrov A, Kiriakova T, Radeva E, Gaydarski L, Denaro F, Paloff A. Identification of degenerated synaptic boutons in the dorsal claustrum of the cat after electrolytic lesions of the intralaminar thalamic nuclei. J Histotechnol 2024:1-9. [PMID: 38564246 DOI: 10.1080/01478885.2024.2335827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 03/23/2024] [Indexed: 04/04/2024]
Abstract
The aim of this study is to investigate whether the dorsal claustrum receives afferent input from the intralaminar thalamic nuclei - centromedian nucleus, central lateral nucleus and paracentral nucleus. The intralaminar thalamic nuclei of eight cats were electrolytically lesioned. We obtained samples from the dorsal claustrum for electron microscopic analysis from the second to the seventh post-procedural day. Two types of degenerated synaptic boutons were observed: electron-dense which formed the majority of boutons, and electron-lucent comprising the remaining samples. Between the second and seventh post-procedural day, we observed a steady increase in the number of electron-dense boutons which were diffusely distributed throughout the dorsal claustrum. Electron-dense degenerated boutons formed asymmetrical contacts with dendritic spines as well as with small and medium-sized dendrites. In contrast, electron-lucent degenerated boutons were observed in earlier post-procedural periods and formed symmetrical axodendritic contacts.
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Affiliation(s)
- Dimka Hinova-Palova
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Sofia, Bulgaria
| | - Boycho Landzhov
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Sofia, Bulgaria
| | - Lawrence Edelstein
- Department of Experimental Neuroanatomy, Medimark Corporation, Del Mar, CA, USA
| | - Khodor Fakih
- Department of Oral and Maxillofacial Surgery, Medical University of Sofia, Sofia, Bulgaria
| | - Alexandar Alexandrov
- Department of Forensic Medicine and Deontology, Medical University of Sofia, Sofia, Bulgaria
| | - Teodora Kiriakova
- Department of Forensic Medicine and Deontology, Medical University of Sofia, Sofia, Bulgaria
| | - Elka Radeva
- Department of Conservative Dentistry, Faculty of Dental Medicine, Medical University Sofia, Sofia, Bulgaria
| | - Lyubomir Gaydarski
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Sofia, Bulgaria
| | - Frank Denaro
- Department of Biology, Morgan State University, Baltimore, MD, USA
| | - Adrian Paloff
- Department of Anatomy, Histology and Embryology, Medical University of Sofia, Sofia, Bulgaria
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Qian P, Manubens-Gil L, Jiang S, Peng H. Non-homogenous axonal bouton distribution in whole-brain single-cell neuronal networks. Cell Rep 2024; 43:113871. [PMID: 38451816 DOI: 10.1016/j.celrep.2024.113871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Revised: 01/08/2024] [Accepted: 02/09/2024] [Indexed: 03/09/2024] Open
Abstract
We examined the distribution of pre-synaptic contacts in axons of mouse neurons and constructed whole-brain single-cell neuronal networks using an extensive dataset of 1,891 fully reconstructed neurons. We found that bouton locations were not homogeneous throughout the axon and among brain regions. As our algorithm was able to generate whole-brain single-cell connectivity matrices from full morphology reconstruction datasets, we further found that non-homogeneous bouton locations have a significant impact on network wiring, including degree distribution, triad census, and community structure. By perturbing neuronal morphology, we further explored the link between anatomical details and network topology. In our in silico exploration, we found that dendritic and axonal tree span would have the greatest impact on network wiring, followed by synaptic contact deletion. Our results suggest that neuroanatomical details must be carefully addressed in studies of whole-brain networks at the single-cell level.
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Affiliation(s)
- Penghao Qian
- New Cornerstone Science Laboratory, SEU-ALLEN Joint Center, State Key Laboratory of Digital Medical Engineering, Institute for Brain and Intelligence, Southeast University, Nanjing, Jiangsu 210096, China; School of Computer Science and Engineering, Southeast University, Nanjing, Jiangsu 210096, China
| | - Linus Manubens-Gil
- New Cornerstone Science Laboratory, SEU-ALLEN Joint Center, State Key Laboratory of Digital Medical Engineering, Institute for Brain and Intelligence, Southeast University, Nanjing, Jiangsu 210096, China.
| | - Shengdian Jiang
- New Cornerstone Science Laboratory, SEU-ALLEN Joint Center, State Key Laboratory of Digital Medical Engineering, Institute for Brain and Intelligence, Southeast University, Nanjing, Jiangsu 210096, China; School of Computer Science and Engineering, Southeast University, Nanjing, Jiangsu 210096, China
| | - Hanchuan Peng
- New Cornerstone Science Laboratory, SEU-ALLEN Joint Center, State Key Laboratory of Digital Medical Engineering, Institute for Brain and Intelligence, Southeast University, Nanjing, Jiangsu 210096, China.
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Yakoubi R, Rollenhagen A, von Lehe M, Shao Y, Sätzler K, Lübke JHR. Quantitative Three-Dimensional Reconstructions of Excitatory Synaptic Boutons in Layer 5 of the Adult Human Temporal Lobe Neocortex: A Fine-Scale Electron Microscopic Analysis. Cereb Cortex 2020; 29:2797-2814. [PMID: 29931200 DOI: 10.1093/cercor/bhy146] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 05/22/2018] [Accepted: 05/29/2018] [Indexed: 11/14/2022] Open
Abstract
Studies of synapses are available for different brain regions of several animal species including non-human primates, but comparatively little is known about their quantitative morphology in humans. Here, synaptic boutons in Layer 5 (L5) of the human temporal lobe (TL) neocortex were investigated in biopsy tissue, using fine-scale electron microscopy, and quantitative three-dimensional reconstructions. The size and organization of the presynaptic active zones (PreAZs), postsynaptic densities (PSDs), and that of the 3 distinct pools of synaptic vesicles (SVs) were particularly analyzed. L5 synaptic boutons were medium-sized (~6 μm2) with a single but relatively large PreAZ (~0.3 μm2). They contained a total of ~1500 SVs/bouton, ~20 constituting the putative readily releasable pool (RRP), ~180 the recycling pool (RP), and the remainder, the resting pool. The PreAZs, PSDs, and vesicle pools are ~3-fold larger than those of CNS synapses in other species. Astrocytic processes reached the synaptic cleft and may regulate the glutamate concentration. Profound differences exist between synapses in human TL neocortex and those described in various species, particularly in the size and geometry of PreAZs and PSDs, the large RRP/RP, and the astrocytic ensheathment suggesting high synaptic efficacy, strength, and modulation of synaptic transmission at human synapses.
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Affiliation(s)
- Rachida Yakoubi
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Astrid Rollenhagen
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany
| | - Marec von Lehe
- University Hospital/Knappschaftskrankenhaus Bochum, In der Schornau 23-25, Bochum, Germany.,Department of Neurosurgery, Ruppiner Kliniken, Medizinische Hochschule Brandenburg, Fehrbelliner Str. 38, Neuruppin, Germany
| | - Yachao Shao
- Simulation Lab Neuroscience, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,College of Computer, National University of Defense Technology, Changsha, China
| | - Kurt Sätzler
- School of Biomedical Sciences, University of Ulster, Cromore Rd., BT52 1SA, Londonderry, UK
| | - Joachim H R Lübke
- Institute of Neuroscience and Medicine INM-10, Research Centre Jülich GmbH, Leo-Brandt Str., Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty/RWTH University Hospital Aachen, Pauwelsstr. 30, Aachen, Germany.,JARA Translational Brain Medicine, Germany
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Rollenhagen A, Walkenfort B, Yakoubi R, Klauke SA, Schmuhl-Giesen SF, Heinen-Weiler J, Voortmann S, Marshallsay B, Palaz T, Holz U, Hasenberg M, Lübke JHR. Synaptic Organization of the Human Temporal Lobe Neocortex as Revealed by High-Resolution Transmission, Focused Ion Beam Scanning, and Electron Microscopic Tomography. Int J Mol Sci 2020; 21:E5558. [PMID: 32756507 DOI: 10.3390/ijms21155558] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 01/02/2023] Open
Abstract
Modern electron microscopy (EM) such as fine-scale transmission EM, focused ion beam scanning EM, and EM tomography have enormously improved our knowledge about the synaptic organization of the normal, developmental, and pathologically altered brain. In contrast to various animal species, comparably little is known about these structures in the human brain. Non-epileptic neocortical access tissue from epilepsy surgery was used to generate quantitative 3D models of synapses. Beside the overall geometry, the number, size, and shape of active zones and of the three functionally defined pools of synaptic vesicles representing morphological correlates for synaptic transmission and plasticity were quantified. EM tomography further allowed new insights in the morphological organization and size of the functionally defined readily releasable pool. Beside similarities, human synaptic boutons, although comparably small (approximately 5 µm), differed substantially in several structural parameters, such as the shape and size of active zones, which were on average 2 to 3-fold larger than in experimental animals. The total pool of synaptic vesicles exceeded that in experimental animals by approximately 2 to 3-fold, in particular the readily releasable and recycling pool by approximately 2 to 5-fold, although these pools seemed to be layer-specifically organized. Taken together, synaptic boutons in the human temporal lobe neocortex represent unique entities perfectly adapted to the “job” they have to fulfill in the circuitry in which they are embedded. Furthermore, the quantitative 3D models of synaptic boutons are useful to explain and even predict the functional properties of synaptic connections in the human neocortex.
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Abstract
The Drosophila melanogaster larval neuromuscular system is extensively used by researchers to study neuronal cell biology, and Drosophila glutamatergic motor neurons have become a major model system. There are two main Types of glutamatergic motor neurons, Ib and Is, with different structural and physiological properties at synaptic level at the neuromuscular junction. To generate genetic tools to identify and manipulate motor neurons of each Type, we screened for GAL4 driver lines for this purpose. Here we describe GAL4 drivers specific for examples of neurons within each Type, Ib or Is. These drivers showed high expression levels and were expressed in only few motor neurons, making them amenable tools for specific studies of both axonal and synapse biology in identified Type I motor neurons.
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Yeh YH, Gunasekharan V, Manuelidis L. A prokaryotic viral sequence is expressed and conserved in mammalian brain. Proc Natl Acad Sci U S A 2017; 114:7118-23. [PMID: 28630311 DOI: 10.1073/pnas.1706110114] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A natural and permanent transfer of prokaryotic viral sequences to mammals has not been reported by others. Circular "SPHINX" DNAs <5 kb were previously isolated from nuclease-protected cytoplasmic particles in rodent neuronal cell lines and brain. Two of these DNAs were sequenced after Φ29 polymerase amplification, and they revealed significant but imperfect homology to segments of commensal Acinetobacter phage viruses. These findings were surprising because the brain is isolated from environmental microorganisms. The 1.76-kb DNA sequence (SPHINX 1.8), with an iteron before its ORF, was evaluated here for its expression in neural cells and brain. A rabbit affinity purified antibody generated against a peptide without homology to mammalian sequences labeled a nonglycosylated ∼41-kDa protein (spx1) on Western blots, and the signal was efficiently blocked by the competing peptide. Spx1 was resistant to limited proteinase K digestion, but was unrelated to the expression of host prion protein or its pathologic amyloid form. Remarkably, spx1 concentrated in selected brain synapses, such as those on anterior motor horn neurons that integrate many complex neural inputs. SPHINX 1.8 appears to be involved in tissue-specific differentiation, including essential functions that preserve its propagation during mammalian evolution, possibly via maternal inheritance. The data here indicate that mammals can share and exchange a larger world of prokaryotic viruses than previously envisioned.
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Lee JY, Geng J, Lee J, Wang AR, Chang KT. Activity-Induced Synaptic Structural Modifications by an Activator of Integrin Signaling at the Drosophila Neuromuscular Junction. J Neurosci 2017; 37:3246-63. [PMID: 28219985 DOI: 10.1523/JNEUROSCI.3128-16.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/08/2017] [Accepted: 02/14/2017] [Indexed: 11/21/2022] Open
Abstract
Activity-induced synaptic structural modification is crucial for neural development and synaptic plasticity, but the molecular players involved in this process are not well defined. Here, we report that a protein named Shriveled (Shv) regulates synaptic growth and activity-dependent synaptic remodeling at the Drosophila neuromuscular junction. Depletion of Shv causes synaptic overgrowth and an accumulation of immature boutons. We find that Shv physically and genetically interacts with βPS integrin. Furthermore, Shv is secreted during intense, but not mild, neuronal activity to acutely activate integrin signaling, induce synaptic bouton enlargement, and increase postsynaptic glutamate receptor abundance. Consequently, loss of Shv prevents activity-induced synapse maturation and abolishes post-tetanic potentiation, a form of synaptic plasticity. Our data identify Shv as a novel trans-synaptic signal secreted upon intense neuronal activity to promote synapse remodeling through integrin receptor signaling.SIGNIFICANCE STATEMENT The ability of neurons to rapidly modify synaptic structure in response to neuronal activity, a process called activity-induced structural remodeling, is crucial for neuronal development and complex brain functions. The molecular players that are important for this fundamental biological process are not well understood. Here we show that the Shriveled (Shv) protein is required during development to maintain normal synaptic growth. We further demonstrate that Shv is selectively released during intense neuronal activity, but not mild neuronal activity, to acutely activate integrin signaling and trigger structural modifications at the Drosophila neuromuscular junction. This work identifies Shv as a key modulator of activity-induced structural remodeling and suggests that neurons use distinct molecular cues to differentially modulate synaptic growth and remodeling to meet synaptic demand.
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Chéreau R, Saraceno GE, Angibaud J, Cattaert D, Nägerl UV. Superresolution imaging reveals activity-dependent plasticity of axon morphology linked to changes in action potential conduction velocity. Proc Natl Acad Sci U S A 2017; 114:1401-6. [PMID: 28115721 DOI: 10.1073/pnas.1607541114] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Axons convey information to nearby and distant cells, and the time it takes for action potentials (APs) to reach their targets governs the timing of information transfer in neural circuits. In the unmyelinated axons of hippocampus, the conduction speed of APs depends crucially on axon diameters, which vary widely. However, it is not known whether axon diameters are dynamic and regulated by activity-dependent mechanisms. Using time-lapse superresolution microscopy in brain slices, we report that axons grow wider after high-frequency AP firing: synaptic boutons undergo a rapid enlargement, which is mostly transient, whereas axon shafts show a more delayed and progressive increase in diameter. Simulations of AP propagation incorporating these morphological dynamics predicted bidirectional effects on AP conduction speed. The predictions were confirmed by electrophysiological experiments, revealing a phase of slowed down AP conduction, which is linked to the transient enlargement of the synaptic boutons, followed by a sustained increase in conduction speed that accompanies the axon shaft widening induced by high-frequency AP firing. Taken together, our study outlines a morphological plasticity mechanism for dynamically fine-tuning AP conduction velocity, which potentially has wide implications for the temporal transfer of information in the brain.
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