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chemical synapse

Alex Fogli Iseppe, Angela Pignatelli, Ottorino Belluzzi
Within the olfactory bulb (OB), periglomerular (PG) cells consist of various types of interneurons, generally classified by their chemical properties such as neurotransmitter and calcium binding proteins. Calretinin (CR) characterizes morphologically and functionally the more numerous and one of the less known subpopulation of PG cells in the OB. Using of transgenic mice expressing eGFP under the CR promoter, we have tried to obtain the first functional characterization of these cells. Electrophysiological recordings were made in these cells using the patch-clamp technique in thin slices...
2016: Frontiers in Cellular Neuroscience
Steven W Barger
Ask any neuroscientist to name the most profound discoveries in the field in the past 60 years, and at or near the top of the list will be a phenomenon or technique related to genes and their expression. Indeed, our understanding of genetics and gene regulation has ushered in whole new systems of knowledge and new empirical approaches, many of which could not have even been imagined prior to the molecular biology boon of recent decades. Neurochemistry, in the classic sense, intersects with these concepts in the manifestation of neuropeptides, obviously dependent upon the central dogma (the established rules by which DNA sequence is eventually converted into protein primary structure) not only for their conformation but also for their levels and locales of expression...
October 17, 2016: Journal of Neurochemistry
Elisa G Krächan, Alexander U Fischer, Jürgen Franke, Eckhard Friauf
At early stations of the auditory pathway, information is encoded in the precise signal timing and rate. Auditory synapses must maintain the relative timing of events with submillisecond precision even during sustained and high-frequency stimulation. In non-auditory brain regions, e.g. telencephalic ones, synapses are activated at considerably lower frequencies. Central to understanding the heterogeneity of synaptic systems is to elucidate the physical, chemical, and biological factors that determine synapse performance...
September 26, 2016: Journal of Physiology
Saurabh Kumar Jha, Niraj Kumar Jha, Dhiraj Kumar, Renu Sharma, Abhishek Shrivastava, Rashmi K Ambasta, Pravir Kumar
The communication between neurons at synaptic junctions is an intriguing process that monitors the transmission of various electro-chemical signals in the central nervous system. Albeit any aberration in the mechanisms associated with transmission of these signals leads to loss of synaptic contacts in both the neocortex and hippocampus thereby causing insidious cognitive decline and memory dysfunction. Compelling evidence suggests that soluble amyloid-β (Aβ) and hyperphosphorylated tau serve as toxins in the dysfunction of synaptic plasticity and aberrant neurotransmitter (NT) release at synapses consequently causing a cognitive decline in Alzheimer's disease (AD)...
September 23, 2016: Journal of Alzheimer's Disease: JAD
Bas van Bommel, Marina Mikhaylova
Synaptic connectivity forms the basis for neuronal communication and the storage of information. Experiences and learning of new abilities can drive remodelling of this connectivity and promotes the formation of spine clusters; dendritic segments with a higher spine density. Spines located within these segments are frequently co-activated, undergo different dynamics than synapses located outside of this dendritic compartment and have, in general, a longer lifetime. Several lines of evidence have shown that chemical synapses located close to each other share or compete for intracellular signalling molecules and structural resources...
September 19, 2016: Neuroscience and Biobehavioral Reviews
Lidia Szczupak
Intercellular interactions in the nervous system are mediated by two types of dedicated structural arrangements: electrical and chemical synapses. Several characteristics distinguish these two mechanisms of communication, such as speed, reliability and the fact that electrical synapses are, potentially, bidirectional. Given these properties, electrical synapses can subserve, in addition to synchrony, three main interrelated network functions: signal amplification, noise reduction and/or coincidence detection...
September 17, 2016: Current Opinion in Neurobiology
Hisae Nishioka, Norie Tooi, Takehisa Isobe, Norio Nakatsuji, Kazuhiro Aiba
Alzheimer's disease (AD) is the most common form of dementia. Cellular AD models derived from human pluripotent stem cells are promising tools in AD research. We recently developed human embryonic stem cell-derived AD models which overexpress mutant Presenilin1 genes, and which exhibit AD phenotypes, including synaptic dysfunction. In this study, we found that our AD models showed reduced levels of RAB3A and SV2B proteins in the pre-synapses, which is a possible cause of electrophysiological abnormalities. Through the screening of chemical compounds using our AD models, we have identified Aβ peptide inhibitors which decrease the concentration of Aβ in culture supernatant...
2016: Scientific Reports
Shaolin Liu, Adam C Puche, Michael T Shipley
UNLABELLED: Sensory processing shapes our perception. In mammals, odor information is encoded by combinatorial activity patterns of olfactory bulb (OB) glomeruli. Glomeruli are richly interconnected by short axon cells (SACs), which form the interglomerular circuit (IGC). It is unclear how the IGC impacts OB output to downstream neural circuits. We combined in vitro and in vivo electrophysiology with optogenetics in mice and found the following: (1) the IGC potently and monosynaptically inhibits the OB output neurons mitral/tufted cells (MTCs) by GABA release from SACs: (2) gap junction-mediated electrical coupling is strong for the SAC→MTC synapse, but negligible for the SAC→ETC synapse; (3) brief IGC-mediated inhibition is temporally prolonged by the intrinsic properties of MTCs; and (4) sniff frequency IGC activation in vivo generates persistent MTC inhibition...
September 14, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Hongying Wei, Fan Liang, Ge Meng, Zhiqing Nie, Ren Zhou, Wei Cheng, Xiaomeng Wu, Yan Feng, Yan Wang
Fine particulate matter (PM2.5) has been implicated as a risk factor for neurodevelopmental disorders including autism in children. However, the underlying biological mechanism remains unclear. DNA methylation is suggested to be a fundamental mechanism for the neuronal responses to environmental cues. We prepared whole particle of PM2.5 (PM2.5), water-soluble extracts (Pw), organic extracts (Po) and carbon core component (Pc) and characterized their chemical constitutes. We found that PM2.5 induced significant redox imbalance, decreased the levels of intercellular methyl donor S-adenosylmethionine and caused global DNA hypomethylation...
2016: Scientific Reports
Adriana De-La-Rosa Tovar, Prashant K Mishra, Francisco F De-Miguel
We studied how a neuronal circuit composed of two neuron types connected by chemical and electrical synapses maintains constant its integrative capacities as neurons grow. For this we combined electrophysiological experiments with mathematical modeling in pairs of electrically-coupled Retzius neurons from postnatal to adult leeches. The electrically-coupled dendrites of both Retzius neurons receive a common chemical input, which produces excitatory postsynaptic potentials (EPSPs) with varying amplitudes. Each EPSP spreads to the soma, but also crosses the electrical synapse to arrive at the soma of the coupled neuron...
2016: Frontiers in Cellular Neuroscience
David Eriksson
To test the importance of a certain cell type or brain area it is common to make a "lack of function" experiment in which the neuronal population of interest is inhibited. Here we review physiological and methodological constraints for making controlled perturbations using the corticothalamic circuit as an example. The brain with its many types of cells and rich interconnectivity offers many paths through which a perturbation can spread within a short time. To understand the side effects of the perturbation one should record from those paths...
2016: Frontiers in Neural Circuits
Friedrich-Wilhelm Schürmann
In the insect brain, mushroom bodies represent a prominent central neuropil for multisensory integration and, crucially, for learning and memory. For this reason, special attention has been focused on its small chemical synapses. Early studies on synaptic types and their distribution, using conventional electron microscopy, and recent publications have resolved basic features of synaptic circuits. More recent studies, using experimental methods for resolving neurons, such as immunocytochemistry, genetic labelling, high resolution confocal microscopy and more advanced electron microscopy, have revealed many new details about the fine structure and molecular contents of identifiable neurons of mushroom bodies and has led to more refined modelling of functional organisation...
October 5, 2016: Arthropod Structure & Development
Rodrigo Lozano, Kerry J Gilmore, Brianna C Thompson, Elise M Stewart, Aaron M Waters, Mario Romero-Ortega, Gordon G Wallace
: Neuromuscular junctions (NMJ) are specialized synapses that link motor neurons with muscle fibers. These sites are fundamental to human muscle activity, controlling swallowing and breathing amongst many other vital functions. Study of this synapse formation is an essential area in neuroscience; the understanding of how neurons interact and control their targets during development and regeneration are fundamental questions. Existing data reveals that during initial stages of development neurons target and form synapses driven by biophysical and biochemical cues, and during later stages they require electrical activity to develop their functional interactions...
November 2016: Acta Biomaterialia
Kenrick An Fu Yap, Mahesh Shivarama Shetty, Gisela Garcia-Alvarez, Bo Lu, Durgadevi Alagappan, Masatsugu Oh-Hora, Sreedharan Sajikumar, Marc Fivaz
STIM2 is an integral membrane protein of the endoplasmic reticulum (ER) that regulates the activity of plasma membrane (PM) channels at ER-PM contact sites. Recent studies show that STIM2 promotes spine maturation and surface expression of the AMPA receptor (AMPAR) subunit GluA1, hinting at a probable role in synaptic plasticity. Here, we used a Stim2 cKO mouse to explore the function of STIM2 in Long-Term Potentiation (LTP) and Depression (LTD), two widely-studied models of synaptic plasticity implicated in information storage...
August 18, 2016: Neurobiology of Learning and Memory
Seongkyun Kim, Hyoungkyu Kim, Jerald D Kralik, Jaeseung Jeong
Determining the fundamental architectural design of complex nervous systems will lead to significant medical and technological advances. Yet it remains unclear how nervous systems evolved highly efficient networks with near optimal sharing of pathways that yet produce multiple distinct behaviors to reach the organism's goals. To determine this, the nematode roundworm Caenorhabditis elegans is an attractive model system. Progress has been made in delineating the behavioral circuits of the C. elegans, however, many details are unclear, including the specific functions of every neuron and synapse, as well as the extent the behavioral circuits are separate and parallel versus integrative and serial...
August 2016: PLoS Computational Biology
Claudio Acuna, Xinran Liu, Thomas C Südhof
RIMs and RIM-binding proteins (RBPs) are evolutionary conserved multidomain proteins of presynaptic active zones that are known to recruit Ca(2+) channels; in addition, RIMs perform well-recognized functions in tethering and priming synaptic vesicles for exocytosis. However, deletions of RIMs or RBPs in mice cause only partial impairments in various active zone functions and have no effect on active zone structure, as visualized by electron micrographs, suggesting that their contribution to active zone functions is limited...
August 17, 2016: Neuron
Rahul Mittal, Luca H Debs, Amit P Patel, Desiree Nguyen, Kunal Patel, Gregory O'Connor, M'hamed Grati, Jeenu Mittal, Denise Yan, Adrien A Eshraghi, Sapna K Deo, Sylvia Daunert, Xue Zhong Liu
Neurotransmitters including catecholamines and serotonin play a crucial role in maintaining homeostasis in the human body. Studies on these neurotransmitters mainly revolved around their role in the "fight or flight" response, transmitting signals across a chemical synapse and modulating blood flow throughout the body. However, recent research has demonstrated that neurotransmitters can play a significant role in the gastrointestinal (GI) physiology. Norepinephrine (NE), epinephrine (E), dopamine (DA), and serotonin have recently been a topic of interest because of their roles in the gut physiology and their potential roles in gastrointestinal and central nervous system pathophysiology...
August 11, 2016: Journal of Cellular Physiology
Xing-Hua Yao, Min Wang, Xiang-Nan He, Fei He, Shu-Qing Zhang, Wenlian Lu, Zi-Long Qiu, Yong-Chun Yu
The coexistence of electrical and chemical synapses among interneurons is essential for interneuron function in the neocortex. However, it remains largely unclear whether electrical coupling between interneurons influences chemical synapse formation and microcircuit assembly during development. Here, we show that electrical and GABAergic chemical connections robustly develop between interneurons in neocortical layer 1 over a similar time course. Electrical coupling promotes action potential generation and synchronous firing between layer 1 interneurons...
2016: Nature Communications
Atul Kumar, Lars Paeger, Kosmas Kosmas, Peter Kloppenburg, Angelika A Noegel, Vivek S Peche
Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2(gt/gt) mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2(gt/gt) with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2(gt/gt) neurons...
2016: Frontiers in Cellular Neuroscience
Qihua Tan, Bastiaan T Heijmans, Jacob V B Hjelmborg, Mette Soerensen, Kaare Christensen, Lene Christiansen
BACKGROUND: Current epigenetic studies on aging are dominated by the cross-sectional design that correlates subjects' ages or age groups with their measured epigenetic profiles. Such studies have been more aimed at age prediction or building up the epigenetic clock of age rather than focusing on the dynamic patterns in epigenetic changes during the aging process. METHODS: We performed an epigenome-wide association study of intra-individual longitudinal changes in DNA methylation at CpG (cytosine-phosphate-guanine) sites measured in whole-blood samples of a cohort of 43 elderly twin pairs followed for 10 years (age at intake 73-82 years)...
August 6, 2016: International Journal of Epidemiology
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