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Isabella Maiellaro, Martin J Lohse, Robert J Kittel, Davide Calebiro
The second messenger cyclic AMP (cAMP) plays an important role in synaptic plasticity. Although there is evidence for local control of synaptic transmission and plasticity, it is less clear whether a similar spatial confinement of cAMP signaling exists. Here, we suggest a possible biophysical basis for the site-specific regulation of synaptic plasticity by cAMP, a highly diffusible small molecule that transforms the physiology of synapses in a local and specific manner. By exploiting the octopaminergic system of Drosophila, which mediates structural synaptic plasticity via a cAMP-dependent pathway, we demonstrate the existence of local cAMP signaling compartments of micrometer dimensions within single motor neurons...
October 25, 2016: Cell Reports
Akira Minami, Masakazu Saito, Shou Mamada, Daisuke Ieno, Tomoya Hikita, Tadanobu Takahashi, Tadamune Otsubo, Kiyoshi Ikeda, Takashi Suzuki
Sialic acid bound to glycans in glycolipids and glycoproteins is essential for synaptic plasticity and memory. Sialidase (EC, which has 4 isozymes including Neu1, Neu2, Neu3 and Neu4, regulates the sialylation level of glycans by removing sialic acid from sialylglycoconjugate. In the present study, we investigated the distribution of sialidase activity in rat hippocampus and the role of sialidase in hippocampal memory processing. We previously developed a highly sensitive histochemical imaging probe for sialidase activity, BTP3-Neu5Ac...
2016: PloS One
Petrina Yau-Pok Lau, Linda Katona, Peter Saghy, Kathryn Newton, Peter Somogyi, Karri P Lamsa
Long-term plasticity is well documented in synapses between glutamatergic principal cells in the cortex both in vitro and in vivo. Long-term potentiation (LTP) and -depression (LTD) have also been reported in glutamatergic connections to hippocampal GABAergic interneurons expressing parvalbumin (PV+) or nitric oxide synthase (NOS+) in brain slices, but plasticity in these cells has not been tested in vivo. We investigated synaptically-evoked suprathreshold excitation of identified hippocampal neurons in the CA1 area of urethane-anaesthetized rats...
October 25, 2016: Brain Structure & Function
Andrew S Powers, Jeffrey Grizzaffi, Richard Ribchester, Gregory A Lnenicka
Studies of synaptic homeostasis during muscle fiber (MF) growth in Drosophila larvae have focused on the regulation of the quantal content of transmitter release. However, early studies in crayfish and frog suggested that regulation of quantal current size may be an integral mechanism in synaptic homeostasis. To examine this further in Drosophila, we compared the electrical properties, miniature excitatory postsynaptic potentials (minEPSPs) and miniature excitatory postsynaptic currents (minEPSCs) in different-sized MFs in third-instar larvae and for a single MF during larval growth...
October 25, 2016: Pflügers Archiv: European Journal of Physiology
Charanya Sampathkumar, Yuan-Ju Wu, Mayur Vadhvani, Thorsten Trimbuch, Britta Eickholt, Christian Rosenmund
Mutations in the MECP2 gene cause the neurodevelopmental disorder Rett syndrome (RTT). Previous studies have shown that altered MeCP2 levels result in aberrant neurite outgrowth and glutamatergic synapse formation. However, causal molecular mechanisms are not well understood since MeCP2 is known to regulate transcription of a wide range of target genes. Here, we describe a key role for a constitutive BDNF feed forward signaling pathway in regulating synaptic response, general growth and differentiation of glutamatergic neurons...
October 26, 2016: ELife
Daniel Ricklin, Edimara S Reis, Dimitrios C Mastellos, Piet Gros, John D Lambris
As a preformed defense system, complement faces a delicate challenge in providing an immediate, forceful response to pathogens even at first encounter, while sparing host cells in the process. For this purpose, it engages a tightly regulated network of plasma proteins, cell surface receptors, and regulators. Complement component C3 plays a particularly versatile role in this process by keeping the cascade alert, acting as a point of convergence of activation pathways, fueling the amplification of the complement response, exerting direct effector functions, and helping to coordinate downstream immune responses...
November 2016: Immunological Reviews
N Wu, U Gaur, Q Zhu, B Chen, Z Xu, X Zhao, M Yang, D Li
MicroRNA (miRNA) is a highly conserved class of small noncoding RNA about 19-24 nucleotides in length that function in a specific manner to post-transcriptionally regulate gene expression in organisms. Tissue miRNA expression studies have discovered a myriad of functions for miRNAs in various aspects, but a role for miRNAs in chicken ovarian tissue at 300 days of age has not hitherto been reported. In this study, we performed the first miRNA analysis of ovarian tissues in chickens with low and high rates of egg production using high-throughput sequencing...
October 26, 2016: Animal Genetics
Yu-Hang Zhang, Chen Chu, Shaopeng Wang, Lei Chen, Jing Lu, XiangYin Kong, Tao Huang, HaiPeng Li, Yu-Dong Cai
A drug's biological half-life is defined as the time required for the human body to metabolize or eliminate 50% of the initial drug dosage. Correctly measuring the half-life of a given drug is helpful for the safe and accurate usage of the drug. In this study, we investigated which gene ontology (GO) terms and biological pathways were highly related to the determination of drug half-life. The investigated drugs, with known half-lives, were analyzed based on their enrichment scores for associated GO terms and KEGG pathways...
2016: PloS One
Joseph G Duman, Kimberley F Tolias
Excitatory synaptic strengthening and the corresponding enlargement of dendritic spines are thought to be essential for learning and memory. In two recent Nature papers, Harward et al. (2016) and Hedrick et al. (2016) provide insight into the mechanisms that regulate these processes and illuminate the molecular basis of crosstalk between synapses.
October 24, 2016: Developmental Cell
Nicholas P Vyleta, Carolina Borges-Merjane, Peter Jonas
Mossy fiber synapses on CA3 pyramidal cells are 'conditional detonators' that reliably discharge postsynaptic targets. The 'conditional' nature implies that burst activity in dentate gyrus granule cells is required for detonation. Whether single unitary excitatory postsynaptic potentials (EPSPs) trigger spikes in CA3 neurons remains unknown. Mossy fiber synapses exhibit both pronounced short-term facilitation and uniquely large post-tetanic potentiation (PTP). We tested whether PTP could convert mossy fiber synapses from subdetonator into detonator mode, using a recently developed method to selectively and noninvasively stimulate individual presynaptic terminals in rat brain slices...
October 25, 2016: ELife
Hao Liu, Wei Ye, Hai-Feng Chen
Acetylcholinesterase is a potent enzyme that regulates neurotransmission by rapidly hydrolyzing the neurotransmitter acetylcholine in synapses of the nervous system. As drug target of anti-AD, it has catalytic and peripheral anionic sites. However, the regulation relation between these two sites is unclear. Therefore, we constructed dynamics fluctuation network based on all-atom molecular dynamics simulations to reveal the regulation mechanism. The results suggest that the correlation network in double site system (hAChE/TZ5) is distinctly different from that in the free state and single site systems (hAChE/huprine and hAChE/1YL)...
October 25, 2016: Chemical Biology & Drug Design
Iva Bruhova, Anthony Auerbach
Acetylcholine (ACh) released at the vertebrate nerve-muscle synapse is hydrolyzed rapidly into choline (Cho), so endplate receptors (AChRs) are exposed to high concentrations of both of these structurally-related ligands. To understand how these receptors distinguish ACh and Cho, we used single-channel electrophysiology to measure resting affinities (binding free energies) of these and other agonists in adult-type mouse AChRs having a mutation(s) at the transmitter-binding sites. The aromatic rings of αY190, αW149 and αY198 each provide ∼50% less binding energy for Cho compared to ACh...
October 25, 2016: Journal of Physiology
Adam J Harrington, Aram Raissi, Kacey Rajkovich, Stefano Berto, Jaswinder Kumar, Gemma Molinaro, Jonathan Raduazzo, Yuhong Guo, Kris Loerwald, Genevieve Konopka, Kimberly M Huber, Christopher W Cowan
Numerous genetic variants associated with MEF2C are linked to autism, intellectual disability (ID) and schizophrenia (SCZ) - a heterogeneous collection of neurodevelopmental disorders with unclear pathophysiology. MEF2C is highly expressed in developing cortical excitatory neurons, but its role in their development remains unclear. We show here that conditional embryonic deletion of Mef2c in cortical and hippocampal excitatory neurons (Emx1-lineage) produces a dramatic reduction in cortical network activity in vivo, due in part to a dramatic increase in inhibitory and a decrease in excitatory synaptic transmission...
October 25, 2016: ELife
Diogo M Rombo, Joaquim A Ribeiro, Ana M Sebastião
Physiological network functioning in the hippocampus is dependent on a balance between glutamatergic cell excitability and the activity of diverse local circuit neurons that release the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Tuners of neuronal communication such as adenosine, an endogenous modulator of synapses, control hippocampal network operations by regulating excitability. Evidence has been recently accumulating on the influence of adenosine on different aspects of GABAergic transmission to shape hippocampal function...
October 25, 2016: Journal of Neurochemistry
Matthew J Gazzellone, Mehdi Zarrei, Christie L Burton, Susan Walker, Mohammed Uddin, S M Shaheen, Julie Coste, Rageen Rajendram, Reva J Schachter, Marlena Colasanto, Gregory L Hanna, David R Rosenberg, Noam Soreni, Kate D Fitzgerald, Christian R Marshall, Janet A Buchanan, Daniele Merico, Paul D Arnold, Stephen W Scherer
BACKGROUND: Obsessive-compulsive disorder (OCD) is a heterogeneous neuropsychiatric condition, thought to have a significant genetic component. When onset occurs in childhood, affected individuals generally exhibit different characteristics from adult-onset OCD, including higher prevalence in males and increased heritability. Since neuropsychiatric conditions are associated with copy number variations (CNVs), we considered their potential role in the etiology of OCD. METHODS: We genotyped 307 unrelated pediatric probands with idiopathic OCD (including 174 that were part of complete parent-child trios) and compared their genotypes with those of 3861 population controls, to identify rare CNVs (<0...
2016: Journal of Neurodevelopmental Disorders
Ji-Xia Chai, Hui-Hui Li, Yuan-Yuan Wang, Qiang Chai, Wen-Xin He, Yan-Mei Zhou, Xiao-Dong Hu, Zhen-Huan Wang
OBJECTIVE: To explore the effect of diallyl disulfide (DADS) on hippocampal synapses and learning and memory abilities in a mouse model of A1zheimer's disease (AD). METHODS: Mouse models of AD established by agglutinated Aβ1-42 injection in the lateral cerebral ventricle were randomized into 4 groups and treated with DADS at the daily doses of 0, 10, 50 and 100 mg/kg by gavage for 30 consecutive days. The learning and memory abilities of the mice were assessed with Morris water maze test; the structures of the dendritic spines and synapses in CA1 region of the hippocampus were observed under transmission electron microscope with silver staining; PSD95 and SYP protein and mRNA expressions in the hippocampus were detected with Western blotting and RT-PCR...
October 20, 2016: Nan Fang Yi Ke da Xue Xue Bao, Journal of Southern Medical University
M A Sotomayor-Sobrino, A Ochoa-Aguilar, L A Méndez-Cuesta, C Gómez-Acevedo
INTRODUCTION: Stroke is one of the leading causes of death in the world; its incidence is increasing due to increased life expectancy. However, treatment options for these patients are limited since no clinically effective drugs have been developed to date. DEVELOPMENT: According to clinical evidence, a number of neurochemical changes take place after stroke, including energy depletion, increased free radical synthesis, calcium accumulation, neurotransmitter imbalance, excitotoxicity, and, at a later stage, immune system activation leading to inflammation...
October 21, 2016: Neurología: Publicación Oficial de la Sociedad Española de Neurología
Christine Gross, Veit Wiesmann, Sebastian Millen, Martina Kalmer, Thomas Wittenberg, Jan Gettemans, Andrea K Thoma-Kress
The delta-retrovirus Human T-cell leukemia virus type 1 (HTLV-1) preferentially infects CD4+ T-cells via cell-to-cell transmission. Viruses are transmitted by polarized budding and by transfer of viral biofilms at the virological synapse (VS). Formation of the VS requires the viral Tax protein and polarization of the host cytoskeleton, however, molecular mechanisms of HTLV-1 cell-to-cell transmission remain incompletely understood. Recently, we could show Tax-dependent upregulation of the actin-bundling protein Fascin (FSCN-1) in HTLV-1-infected T-cells...
October 2016: PLoS Pathogens
Roman Dvorkin, Noam E Ziv
The idea that synaptic properties are defined by specific pre- and postsynaptic activity histories is one of the oldest and most influential tenets of contemporary neuroscience. Recent studies also indicate, however, that synaptic properties often change spontaneously, even in the absence of specific activity patterns or any activity whatsoever. What, then, are the relative contributions of activity history-dependent and activity history-independent processes to changes synapses undergo? To compare the relative contributions of these processes, we imaged, in spontaneously active networks of cortical neurons, glutamatergic synapses formed between the same axons and neurons or dendrites under the assumption that their similar activity histories should result in similar size changes over timescales of days...
October 2016: PLoS Biology
Xiaojie Liu, Yao Chen, Casey R Vickstrom, Yan Li, Andreu Viader, Benjamin F Cravatt, Qing-Song Liu
The endocannabinoid 2-arachidonoylglycerol (2-AG) mediates retrograde synaptic depression including depolarization-induced suppression of excitation (DSE) and inhibition (DSI). 2-AG is degraded primarily by monoacylglycerol lipase (MAGL), which is expressed in neurons and astrocytes. Using knockout mice in which MAGL is deleted globally or selectively in neurons or astrocytes, we investigated the relative contribution of neuronal and astrocytic MAGL to the termination of DSE and DSI in Purkinje cells (PCs) in cerebellar slices...
October 24, 2016: Scientific Reports
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