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https://www.readbyqxmd.com/read/28424589/the-calcium-channel-c-terminal-and-synaptic-vesicle-tethering-analysis-by-immuno-nanogold-localization
#1
Robert H C Chen, Qi Li, Christine A Snidal, Sabiha R Gardezi, Elise F Stanley
At chemical synapses the incoming action potential triggers the influx of Ca(2+) through voltage-sensitive calcium channels (CaVs, typically CaV2.1 and 2.2) and the ions binds to sensors associated with docked, transmitter filled synaptic vesicles (SVs), triggering their fusion and discharge. The CaVs and docked SVs are located within the active zone (AZ) region of the synapse which faces a corresponding neurotransmitter receptor-rich region on the post-synaptic cell. Evidence that the fusion of a SV can be gated by Ca(2+) influx through a single CaV suggests that the channel and docked vesicle are linked by one or more molecular tethers (Stanley, 1993)...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28410051/information-rate-analysis-of-a-synaptic-release-site-using-a-two-state-model-of-short-term-depression
#2
Mehrdad Salmasi, Martin Stemmler, Stefan Glasauer, Alex Loebel
Synapses are the communication channels for information transfer between neurons; these are the points at which pulse-like signals are converted into the stochastic release of quantized amounts of chemical neurotransmitter. At many synapses, prior neuronal activity depletes synaptic resources, depressing subsequent responses of both spontaneous and spike-evoked releases. We analytically compute the information transmission rate of a synaptic release site, which we model as a binary asymmetric channel. Short-term depression is incorporated by assigning the channel a memory of depth one...
April 14, 2017: Neural Computation
https://www.readbyqxmd.com/read/28397972/aging-dependent-expression-of-synapse-related-proteins-in-the-mouse-brain
#3
Hajime Shiotani, Tomohiko Maruo, Shotaro Sakakibara, Muneaki Miyata, Kenji Mandai, Hideki Mochizuki, Yoshimi Takai
A synapse is a cell adhesion structure that permits a neuron to pass a chemical or electrical signal to another neuron. They connect neurons and form neural networks that are essential for brain functions, such as learning and memory. At a chemical synapse, the presynapse and the postsynapse are connected by cell adhesion molecules. The presynapse contains synaptic vesicles and their release machinery, whereas the postsynapse contains postsynaptic densities and receptors for the neurotransmitters. Many proteins constituting a synapse have been identified, but their life-span expression profiles remain elusive...
April 11, 2017: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
https://www.readbyqxmd.com/read/28384220/functional-asymmetry-and-plasticity-of-electrical-synapses-interconnecting-neurons-through-a-36-state-model-of-gap-junction-channel-gating
#4
Mindaugas Snipas, Lina Rimkute, Tadas Kraujalis, Kestutis Maciunas, Feliksas F Bukauskas
We combined the Hodgkin-Huxley equations and a 36-state model of gap junction channel gating to simulate electrical signal transfer through electrical synapses. Differently from most previous studies, our model can account for dynamic modulation of junctional conductance during the spread of electrical signal between coupled neurons. The model of electrical synapse is based on electrical properties of the gap junction channel encompassing two fast and two slow gates triggered by the transjunctional voltage...
April 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28381725/pursuit-of-neurotransmitter-functions-being-attracted-with-fascination-of-the-synapse
#5
Shiro Konishi
 In the beginning of the 1970s, only two chemical substances, acetylcholine and γ-aminobutyric acid (GABA), had been definitely established as neurotransmitters. Under such circumstances, I started my scientific career in Professor Masanori Otsuka's lab searching for the transmitter of primary sensory neurons. Until 1976, lines of evidence had accumulated indicating that the undecapeptide substance P could be released as a transmitter from primary afferent fibers into spinal synapses, although the substance P-mediated synaptic response had yet to be identified...
2017: Yakugaku Zasshi: Journal of the Pharmaceutical Society of Japan
https://www.readbyqxmd.com/read/28377435/drawing-on-student-knowledge-of-neuroanatomy-and-neurophysiology
#6
Tara N Slominski, Jennifer L Momsen, Lisa M Montplaisir
Drawings are an underutilized assessment format in Human Anatomy and Physiology (HA&P), despite their potential to reveal student content understanding and alternative conceptions. This study used student-generated drawings to explore student knowledge in a HA&P course. The drawing tasks in this study focused on chemical synapses between neurons, an abstract concept in HA&P. Using two preinstruction drawing tasks, students were asked to depict synaptic transmission and summation. In response to the first drawing task, 20% of students (n = 352) created accurate representations of neuron anatomy...
June 1, 2017: Advances in Physiology Education
https://www.readbyqxmd.com/read/28369952/a-calcium-dependent-pathway-underlies-activity-dependent-plasticity-of-electrical-synapses-in-the-thalamic-reticular-nucleus
#7
Jessica Sevetson, Sarah Fittro, Emily Heckman, Julie S Haas
Recent results have demonstrated modification of electrical synapse strength by varied forms of neuronal activity. However, the mechanisms underlying plasticity induction in central mammalian neurons are unclear. Here we show that the two established inductors of plasticity at electrical synapses in the thalamic reticular nucleus - paired burst spiking in coupled neurons, and mGluR-dependent tetanization of synaptic input - are separate pathways that converge at a common downstream endpoint. Using occlusion experiments and pharmacology in patched pairs of coupled neurons in vitro, we show that burst-induced depression depends on calcium entry via voltage-gated channels, is blocked by BAPTA chelation, and recruits intracellular calcium release on its way to activation of phosphatase activity...
March 29, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28367405/synaptic-vesicles-isolated-from-the-electric-organ-of-torpedo-californica-and-from-the-central-nervous-system-of-mus-musculus-contain-small-ribonucleic-acids-srnas
#8
Huinan Li, Cheng Wu, Rodolfo Aramayo, Matthew S Sachs, Mark L Harlow
Synaptic vesicles (SVs) are presynaptic organelles that load and release small molecule neurotransmitters at chemical synapses. In addition to classic neurotransmitters, we have demonstrated that SVs isolated from the Peripheral Nervous Systems (PNS) of the electric organ of Torpedo californica, a model cholinergic synapse, and SVs isolated from the Central Nervous System (CNS) of Mus musculus (mouse) contain small ribonucleic acids (sRNAs; ≤ 50 nucleotides) (Scientific Reports, 5:1-14(14918) Li et al. (2015) [1])...
June 2017: Genomics Data
https://www.readbyqxmd.com/read/28361181/putting-a-brake-on-synaptic-vesicle-endocytosis
#9
REVIEW
Ya-Long Wang, Claire Xi Zhang
In chemical synapses, action potentials evoke synaptic vesicle fusion with the presynaptic membrane at the active zone to release neurotransmitter. Synaptic vesicle endocytosis (SVE) then follows exocytosis to recapture vesicle proteins and lipid components for recycling and the maintenance of membrane homeostasis. Therefore, SVE plays an essential role during neurotransmission and is one of the most precisely regulated biological processes. Four modes of SVE have been characterized and both positive and negative regulators have been identified...
March 30, 2017: Cellular and Molecular Life Sciences: CMLS
https://www.readbyqxmd.com/read/28334604/the-potential-role-of-gap-junctional-plasticity-in-the-regulation-of-state
#10
REVIEW
Philippe Coulon, Carole E Landisman
Electrical synapses are the functional correlate of gap junctions and allow transmission of small molecules and electrical current between coupled neurons. Instead of static pores, electrical synapses are actually plastic, similar to chemical synapses. In the thalamocortical system, gap junctions couple inhibitory neurons that are similar in their biochemical profile, morphology, and electrophysiological properties. We postulate that electrical synaptic plasticity among inhibitory neurons directly interacts with the switching between different firing patterns in a state-dependent and type-dependent manner...
March 22, 2017: Neuron
https://www.readbyqxmd.com/read/28320843/distinct-actions-of-voltage-activated-ca-2-channel-block-on-spontaneous-release-at-excitatory-and-inhibitory-central-synapses
#11
Timur Tsintsadze, Courtney L Williams, Dennis J Weingarten, Henrique von Gersdorff, Stephen M Smith
At chemical synapses, voltage-activated calcium channels (VACCs) mediate Ca(2+) influx to trigger action potential-evoked neurotransmitter release. However, the mechanisms by which Ca(2+) regulates spontaneous transmission have not been fully determined. We have shown that VACCs are a major trigger of spontaneous release at neocortical inhibitory synapses but not at excitatory synapses, suggesting fundamental differences in spontaneous neurotransmission at GABAergic and glutamatergic synapses. Recently, VACC blockers were reported to reduce spontaneous release of glutamate and it was proposed that there was conservation of underlying mechanisms of neurotransmission at excitatory and inhibitory synapses...
April 19, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28317880/antidromic-rectifying-gap-junctions-amplify-chemical-transmission-at-functionally-mixed-electrical-chemical-synapses
#12
Ping Liu, Bojun Chen, Roger Mailler, Zhao-Wen Wang
Neurons communicate through chemical synapses and electrical synapses (gap junctions). Although these two types of synapses often coexist between neurons, little is known about whether they interact, and whether any interactions between them are important to controlling synaptic strength and circuit functions. By studying chemical and electrical synapses between premotor interneurons (AVA) and downstream motor neurons (A-MNs) in the Caenorhabditis elegans escape circuit, we found that disrupting either the chemical or electrical synapses causes defective escape response...
March 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28295002/-ultrastructural-characteristics-of-gap-junctions-in-human-glial-brain-tumors
#13
E Yu Kirichenko, A F Savchenko, D V Kozachenko, A E Matsionis, A K Logvinov
AIM: to conduct an electron microscopic study of intercellular communication in the samples of gemistocytic astrocytoma, oligodendroglioma, and glioblastoma. MATERIAL AND METHODS: Surgically resected tumor tissue fragments were fixed in 2.5% glutaraldehyde solution, afterfixed in 1% OsO4 solution, dehydrated, and embedded in epoxy resin. Ultrathin sections were examined using a Jem 1011 electron microscope (Jeol, Japan). RESULTS: Solitary and closely spaced gap junctions (GJs) formed by the thin processes that have the ultrastructure of an astroglial processes were identified in the astrocytoma samples...
2017: Arkhiv Patologii
https://www.readbyqxmd.com/read/28286129/fret-based-sensors-unravel-activation-and-allosteric-modulation-of-the-gabab-receptor
#14
Nathalie Lecat-Guillet, Carine Monnier, Xavier Rovira, Julie Kniazeff, Laurent Lamarque, Jurriaan M Zwier, Eric Trinquet, Jean-Philippe Pin, Philippe Rondard
The main inhibitory neurotransmitter, γ-aminobutyric acid (GABA), modulates many synapses by activating the G protein-coupled receptor GABAB, which is a target for various therapeutic applications. It is an obligatory heterodimer made of GB1 and GB2 that can be regulated by positive allosteric modulators (PAMs). The molecular mechanism of activation of the GABAB receptor remains poorly understood. Here, we have developed FRET-based conformational GABAB sensors compatible with high-throughput screening. We identified conformational changes occurring within the extracellular and transmembrane domains upon receptor activation, which are smaller than those observed in the related metabotropic glutamate receptors...
March 16, 2017: Cell Chemical Biology
https://www.readbyqxmd.com/read/28267198/serotonergic-transmission-at-merkel-discs-modulation-by-exogenously-applied-chemical-messengers-and-involvement-of-ih-currents
#15
Weipang Chang, Hirosato Kanda, Ryo Ikeda, Jennifer Ling, Jianguo G Gu
The Merkel disc is a main type of tactile end organ consisting of Merkel cells and Aβ-afferent endings that responds to tactile stimulation with slowly adapting type 1 (SA1) afferent impulses. Our recent study has shown that Merkel discs in whisker hair follicles are serotonergic synapses using endogenous serotonin to transmit tactile signals from Merkel cells to Aβ-afferent endings. In the present study, we hypothesize that tactile sensitivity of Merkel discs can be modulated by chemical messengers. We tested this hypothesis by determining whether and how SA1 responses of mouse whisker hair follicles may be affected by exogenously applied chemical messengers...
March 7, 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/28265099/neonatal-cx26-removal-impairs-neocortical-development-and-leads-to-elevated-anxiety
#16
Xin Su, Jing-Jing Chen, Lin-Yun Liu, Qian Huang, Li-Zhao Zhang, Xiao-Yang Li, Xiang-Nan He, Wenlian Lu, Shan Sun, Huawei Li, Yong-Chun Yu
Electrical coupling between excitatory neurons in the neocortex is developmentally regulated. It is initially prominent but eliminated at later developmental stages when chemical synapses emerge. However, it remains largely unclear whether early electrical coupling networks broadly contribute to neocortical circuit formation and animal behavior. Here, we report that neonatal electrical coupling between neocortical excitatory neurons is critical for proper neuronal development, synapse formation, and animal behavior...
March 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28260370/mimicking-neurotransmitter-release-in-chemical-synapses-via-hysteresis-engineering-in-mos2-transistors
#17
Andrew J Arnold, Ali Razavieh, Joseph R Nasr, Daniel S Schulman, Chad M Eichfeld, Saptarshi Das
Neurotransmitter release in chemical synapses is fundamental to diverse brain functions such as motor action, learning, cognition, emotion, perception, and consciousness. Moreover, improper functioning or abnormal release of neurotransmitter is associated with numerous neurological disorders such as epilepsy, sclerosis, schizophrenia, Alzheimer's disease, and Parkinson's disease. We have utilized hysteresis engineering in a back-gated MoS2 field effect transistor (FET) in order to mimic such neurotransmitter release dynamics in chemical synapses...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28238793/differential-maturation-of-the-two-regulated-secretory-pathways-in-human-ipsc-derived-neurons
#18
Javier Emperador Melero, Aishwarya G Nadadhur, Desiree Schut, Jan V Weering, Vivi M Heine, Ruud F Toonen, Matthijs Verhage
Neurons communicate by regulated secretion of chemical signals from synaptic vesicles (SVs) and dense-core vesicles (DCVs). Here, we investigated the maturation of these two secretory pathways in micro-networks of human iPSC-derived neurons. These micro-networks abundantly expressed endogenous SV and DCV markers, including neuropeptides. DCV transport was microtubule dependent, preferentially anterograde in axons, and 2-fold faster in axons than in dendrites. SV and DCV secretion were strictly Ca(2+) and SNARE dependent...
March 14, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28228251/spatial-and-temporal-regulation-of-receptor-endocytosis-in-neuronal-dendrites-revealed-by-imaging-of-single-vesicle-formation
#19
Morgane Rosendale, Damien Jullié, Daniel Choquet, David Perrais
Endocytosis in neuronal dendrites is known to play a critical role in synaptic transmission and plasticity such as long-term depression (LTD). However, the inability to detect endocytosis directly in living neurons has hampered studies of its dynamics and regulation. Here, we visualized the formation of individual endocytic vesicles containing pHluorin-tagged receptors with high temporal resolution in the dendrites of cultured hippocampal neurons. We show that transferrin receptors (TfRs) are constitutively internalized at optically static clathrin-coated structures...
February 21, 2017: Cell Reports
https://www.readbyqxmd.com/read/28214749/impairment-in-the-mesohippocampal-dopamine-circuit-following-exposure-to-the-brominated-flame-retardant-hbcdd
#20
Camille Pham-Lake, Elizabeth B Aronoff, Chad R Camp, Aimee Vester, Sam J Peters, W Michael Caudle
Many chemicals have been used to increase the safety of consumer products by reducing their flammability and risk for ignition. Recent focus on brominated flame retardants, such as polybrominated diphenyl ethers (PBDEs) has shown them to contribute to neurobehavioral deficits in children, including learning and memory. As the manufacture and use of PBDEs have been reduced, replacement chemicals, such as hexabromocyclododecane (HBCDD) have been substituted. Our current study evaluated the neurotoxicity of HBCDD, concentrating on dopaminergic innervation to the hippocampus...
March 2017: Environmental Toxicology and Pharmacology
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