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https://www.readbyqxmd.com/read/28539418/loss-of-doc2-dependent-spontaneous-neurotransmission-augments-glutamatergic-synaptic-strength
#1
Denise M O Ramirez, Devon C Crawford, Natali L Chanaday, Brent Trauterman, Lisa M Monteggia, Ege T Kavalali
Action potential-evoked vesicle fusion comprises the majority of neurotransmission within chemical synapses, but action potential-independent spontaneous neurotransmission also contributes to the collection of signals sent to the postsynaptic cell. Previous work has implicated spontaneous neurotransmission in homeostatic synaptic scaling, but few studies have selectively manipulated spontaneous neurotransmission without substantial changes in evoked neurotransmission to study this function in detail. Here we used a quadruple knockdown strategy to reduce levels of proteins within the soluble calcium-binding double C2 domain (Doc2)-like protein family to selectively reduce spontaneous neurotransmission in cultured mouse and rat neurons...
May 24, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28530549/a-genetic-basis-for-molecular-asymmetry-at-vertebrate-electrical-synapses
#2
Adam C Miller, Alex C Whitebirch, Arish N Shah, Kurt C Marsden, Michael Granato, John O'Brien, Cecilia B Moens
Neural network function is based upon the patterns and types of connections made between neurons. Neuronal synapses are adhesions specialized for communication and they come in two types, chemical and electrical. Communication at chemical synapses occurs via neurotransmitter release whereas electrical synapses utilize gap junctions for direct ionic and metabolic coupling. Electrical synapses are often viewed as symmetrical structures, with the same components making both sides of the gap junction. By contrast, we show that a broad set of electrical synapses in zebrafish, Danio rerio, require two gap-junction-forming Connexins for formation and function...
May 22, 2017: ELife
https://www.readbyqxmd.com/read/28528963/neuronal-activity-patterns-in-the-developing-barrel-cortex
#3
Heiko J Luhmann, Rustem Khazipov
The developing barrel cortex reveals a rich repertoire of neuronal activity patterns, which have been also found in other sensory neocortical areas and in other species including the somatosensory cortex of preterm human infants. The earliest stage is characterized by asynchronous, sparse single cell firing at low frequencies. During the second stage neurons show correlated firing, which is initially mediated by electrical synapses and subsequently transforms into network bursts depending on chemical synapses...
May 18, 2017: Neuroscience
https://www.readbyqxmd.com/read/28518110/external-excitation-of-neurons-using-electric-and-magnetic-fields-in-one-and-two-dimensional-cultures
#4
Shani Stern, Assaf Rotem, Yuri Burnishev, Eyal Weinreb, Elisha Moses
A neuron will fire an action potential when its membrane potential exceeds a certain threshold. In typical activity of the brain, this occurs as a result of chemical inputs to its synapses. However, neurons can also be excited by an imposed electric field. In particular, recent clinical applications activate neurons by creating an electric field externally. It is therefore of interest to investigate how the neuron responds to the external field and what causes the action potential. Fortunately, precise and controlled application of an external electric field is possible for embryonic neuronal cells that are excised, dissociated and grown in cultures...
May 7, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28515683/a-population-of-projection-neurons-that-inhibits-the-lateral-horn-but-excites-the-antennal-lobe-through-chemical-synapses-in-drosophila
#5
Kazumichi Shimizu, Mark Stopfer
In the insect olfactory system, odor information is transferred from the antennal lobe (AL) to higher brain areas by projection neurons (PNs) in multiple AL tracts (ALTs). In several species, one of the ALTs, the mediolateral ALT (mlALT), contains some GABAergic PNs; in the Drosophila brain, the great majority of ventral PNs (vPNs) are GABAergic and project through this tract to the lateral horn (LH). Most excitatory PNs (ePNs), project through the medial ALT (mALT) to the mushroom body (MB) and the LH. Recent studies have shown that GABAergic vPNs play inhibitory roles at their axon terminals in the LH...
2017: Frontiers in Neural Circuits
https://www.readbyqxmd.com/read/28499269/identification-of-novel-serotonin-reuptake-inhibitors-targeting-central-and-allosteric-binding-sites-a-virtual-screening-and-molecular-dynamics-simulations-study
#6
Ismail Erol, Busecan Aksoydan, Isik Kantarcioglu, Ramin E Salmas, Serdar Durdagi
The serotonin (5-hydroxytryptamine, 5HT) transporter (SERT) is a member of neurotransmitter sodium symporter (NSS) family, which maintains neurotransmitter by reuptaking 5HT into synapses. Decrease in serotonin concentrations in synaptic clefts have been reported to cause psychological and neurological disorders. Therefore, inhibition of SERT is a potent strategy for the treatment of related diseases such as depression. In this study, approximately 260,000 small molecules from an available chemical database have been virtually screened both at central and allosteric binding sites of SERT to identify potent novel candidate SERT inhibitors...
March 22, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28481020/activation-of-ryanodine-receptors-is-required-for-pka-mediated-downregulation-of-a-type-k-channels-in-rat-hippocampal-neurons
#7
Yoon-Sil Yang, Sang-Chan Jeon, Moon-Suk Kang, Seon-Hee Kim, Su-Yong Eun, Soo-Hee Jin, Sung-Cherl Jung
A-type K(+) channels (IA channels) contribute to learning and memory mechanisms by regulating neuronal excitabilities in the CNS, and their expression level is targeted by Ca(2+) influx via synaptic NMDA receptors (NMDARs) during long-term potentiation (LTP). However, it is not clear how local synaptic Ca(2+) changes induce IA downregulation throughout the neuron, extending from the active synapse to the soma. In this study, we tested if two major receptors of endoplasmic reticulum (ER), ryanodine (RyRs), and IP3 (IP3 R) receptors, are involved in Ca(2+) -mediated IA downregulation in cultured hippocampal neurons of rats...
May 8, 2017: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/28476120/central-peptidergic-modulation-of-peripheral-olfactory-responses
#8
Sion Lee, Young-Joon Kim, Walton D Jones
BACKGROUND: Animal olfactory systems detect volatile environmental chemicals and integrate this information to direct the discovery of food and mates as well as danger avoidance. Rather than remaining constant, olfactory response thresholds are modulated by internal and external cues to adapt odor-guided behaviors to changing conditions. RESULTS: Here, we show in Drosophila melanogaster that neuropeptide F (NPF) modulates the responses of a specific population of antennal olfactory sensory neurons (OSNs) to food-derived odors...
May 5, 2017: BMC Biology
https://www.readbyqxmd.com/read/28470527/functional-viability-measurement-of-synaptic-vesicle-pool-sizes
#9
Jana K Wrosch, Teja W Groemer
Neurons and their function of conveying information across a chemical synapse are highly regulated systems. Impacts on their functional viability can occur independently from changes in morphology. Here we describe a method to assess the size of synaptic vesicle pools using live cell fluorescence imaging and a genetically encoded probe (pHluorin). Assessing functional parameters such as the size of synaptic vesicle pools can be a valuable addition to common assays of neuronal cell viability as they demonstrate that key cellular functions are intact...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28467650/astrocyte-dysfunction-in-alzheimer-disease
#10
REVIEW
Crystal Acosta, Hope D Anderson, Christopher M Anderson
Astrocytes are glial cells that are distributed throughout the central nervous system in an arrangement optimal for chemical and physical interaction with neuronal synapses and brain blood supply vessels. Neurotransmission modulates astrocytic excitability by activating an array of cell surface receptors and transporter proteins, resulting in dynamic changes in intracellular Ca(2+) or Na(+) . Ionic and electrogenic astrocytic changes, in turn, drive vital cell nonautonomous effects supporting brain function, including regulation of synaptic activity, neuronal metabolism, and regional blood supply...
May 3, 2017: Journal of Neuroscience Research
https://www.readbyqxmd.com/read/28462907/electron-holography-on-hfo2-hfo2-x-bilayer-structures-with-multilevel-resistive-switching-properties
#11
G Niu, M A Schubert, S U Sharath, P Zaumseil, S Vogel, C Wenger, E Hildebrandt, S Bhupathi, E Perez, L Alff, M Lehmann, T Schroeder, T Niermann
Unveiling the physical nature of the oxygen-deficient conductive filaments (CFs) that are responsible for the resistive switching of the HfO2-based resistive random access memory (RRAM) devices represents a challenging task due to the oxygen vacancy related defect nature and nanometer size of the CFs. As a first important step to this goal, we demonstrate in this work direct visualization and a study of physico-chemical properties of oxygen-deficient amorphous HfO2-x by carrying out transmission electron microscopy electron holography as well as energy dispersive x-ray spectroscopy on HfO2/HfO2-x bilayer heterostructures, which are realized by reactive molecular beam epitaxy...
May 26, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28461339/canonical-jak-stat-signaling-is-pivotal-for-long-term-depression-at-adult-hippocampal-temporoammonic-ca1-synapses
#12
Gemma McGregor, Andrew J Irving, Jenni Harvey
The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway is involved in numerous cellular processes and it is implicated in neurodegenerative disorders, like Alzheimer disease. Recent studies identified a crucial role for this pathway in activity-dependent long-term depression (LTD) at hippocampal Schaffer collateral (SC)-CA1 synapses. However, it is unclear if JAK-STAT signaling also regulates excitatory synaptic function at the anatomically distinct temporoammonic (TA) input to CA1 neurons...
May 1, 2017: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/28450536/variable-action-potential-backpropagation-during-tonic-firing-and-low-threshold-spike-bursts-in-thalamocortical-but-not-thalamic-reticular-nucleus-neurons
#13
William M Connelly, Vincenzo Crunelli, Adam C Errington
Backpropagating action potentials (bAPs) are indispensable in dendritic signaling. Conflicting Ca(2+) imaging data and an absence of dendritic recording data means the extent of backpropagation in thalamocortical (TC) and thalamic reticular nucleus (TRN) neurons remains unknown. Since TRN neurons signal electrically through dendrodendritic gap junctions and possibly via chemical dendritic GABAergic synapses, as well as classical axonal GABA release, this lack of knowledge is problematic. To address this issue, we made 2-photon targeted patch clamp recordings from rat TC and TRN neuron dendrites to directly measure bAPs...
April 27, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28449070/in-situ-screening-for-postsynaptic-cell-adhesion-molecules-during-synapse-formation
#14
Takeshi Uemura, Tomoko Shiroshima, Asami Maeda, Misato Yasumura, Takashi Shimada, Yuko Fukata, Masaki Fukata, Tomoyuki Yoshida
Neuronal synapse formation is regulated by pre- and postsynaptic cell adhesion molecules. Presynaptic neurexins (NRXNs) and receptor protein tyrosine phosphatases (RPTPs; PTPδ, PTPσ, and LAR in mammals) can induce postsynaptic differentiation through the interaction with various postsynaptic cell adhesion molecules. Here, we developed a novel in situ screening method to identify postsynaptic membranous proteins involved in synaptogenesis. Magnetic beads coated with the extracellular domains of NRXN1β(-S4) and PTPδ-A6 variants preferentially induced excitatory postsynaptic differentiation on the beads' surface when co-cultured with cortical neurons...
April 25, 2017: Journal of Biochemistry
https://www.readbyqxmd.com/read/28446587/temporal-integration-and-1-f-power-scaling-in-a-circuit-model-of-cerebellar-interneurons
#15
Reinoud Maex, Boris Samuel Gutkin
Inhibitory interneurons interconnected via electrical and chemical (GABAA receptor) synapses form extensive circuits in several brain regions. They are thought to be involved in timing and synchronization through fast feed-forward control of principal neurons. Theoretical studies have shown, however, that whereas self-inhibition does indeed reduce response duration, lateral inhibition, in contrast, may generate slow response components through a process of gradual disinhibition. Here we simulated a circuit of interneurons (stellate and basket cells) of the molecular layer of the cerebellar cortex, and observed circuit time-constants that could rise, depending on the parameter values, to more than one second...
April 26, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28424589/the-calcium-channel-c-terminal-and-synaptic-vesicle-tethering-analysis-by-immuno-nanogold-localization
#16
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
#17
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
#18
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...
May 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
#19
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
#20
REVIEW
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
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