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https://www.readbyqxmd.com/read/28650315/transient-acidosis-while-retrieving-a-fear-related-memory-enhances-its-lability
#1
Jianyang Du, Margaret P Price, Rebecca J Taugher, Daniel Grigsby, Jamison J Ash, Austin C Stark, Md Zubayer Hossain Saad, Kritika Singh, Juthika Mandal, John A Wemmie, Michael J Welsh
Attenuating the strength of fearful memories could benefit people disabled by memories of past trauma. Pavlovian conditioning experiments indicate that a retrieval cue can return a conditioned aversive memory to a labile state. However, means to enhance retrieval and render a memory more labile are unknown. We hypothesized that augmenting synaptic signaling during retrieval would increase memory lability. To enhance synaptic transmission, mice inhaled CO2 to induce an acidosis and activate acid sensing ion channels...
June 26, 2017: ELife
https://www.readbyqxmd.com/read/28641228/relationships-between-past-and-present-pesticide-applications-and-pollution-at-a-watershed-outlet-the-case-of-a-horticultural-catchment-in-martinique-french-west-indies
#2
Charles Mottes, Magalie Lesueur Jannoyer, Marianne Le Bail, Mathilde Guéné, Céline Carles, Eric Malézieux
The understanding of factors affecting pesticide transfers to catchment outlet is still at a very early stage in tropical context, and especially on tropical volcanic context. We performed on-farm pesticide use surveys during 87 weeks and monitored pesticides in water weekly during 67 weeks at the outlet of a small catchment in Martinique. We identified three types of pollution. First, we showed long-term chronic pollution by chlordecone, diuron and metolachlor resulting from horticultural practices applied 5-20 years ago (quantification frequency higher than 80%)...
June 16, 2017: Chemosphere
https://www.readbyqxmd.com/read/28636478/pathway-and-rate-limiting-step-of-glyphosate-degradation-by-aspergillus-oryzae-a-f02
#3
Gui-Ming Fu, Yan Chen, Ru-Yi Li, Xiao-Qiang Yuan, Cheng-Mei Liu, Bin Li, Yin Wan
Aspergillus oryzae A-F02, a glyphosate-degrading fungus, was isolated from an aeration tank in a pesticide factory. The pathway and rate-limiting step of glyphosate (GP) degradation were investigated through metabolite analysis. GP, aminomethylphosphonic acid (AMPA) and methylamine were detected in the fermentation liquid of A. oryzae A-F02, whereas sarcosine and glycine were not. The pathway of GP degradation in A. oryzae A-F02 was revealed: GP was firstly degraded into AMPA, which was then degraded into methylamine...
June 21, 2017: Preparative Biochemistry & Biotechnology
https://www.readbyqxmd.com/read/28636281/aryl-and-heteroaryl-substituted-phenylalanines-as-ampa-receptor-ligands
#4
Ewa Szymańska, Paulina Chałupnik, Tommy N Johansen, Birgitte Nielsen, Ana Maria Cuñado Moral, Darryl S Pickering, Anna Więckowska, Katarzyna Kieć-Kononowicz
A series of racemic unnatural amino acids was rationally designed on the basis of recently published X-ray structures of the GluA2 LBD with bound phenylalanine-based antagonists. Twelve new diaryl- or aryl/heteroaryl-substituted phenylalanine derivatives were synthesized and evaluated in vitro in radioligand binding assays at native rat ionotropic glutamate receptors. The most interesting compound in this series, (RS)-2-amino-3-(3'-hydroxy-5-(1H-pyrazol-4-yl)-[1,1'-biphenyl]-3-yl)propanoic acid 7e, showed the binding affinity of 4...
June 21, 2017: Chemical Biology & Drug Design
https://www.readbyqxmd.com/read/28631831/spatial-and-temporal-trends-and-flow-dynamics-of-glyphosate-and-other-pesticides-within-an-agricultural-watershed-in-argentina
#5
Débora J Pérez, Elena Okada, Eduardo De Gerónimo, Mirta L Menone, Virginia C Aparicio, José L Costa
In the present study, we evaluated the spatial and temporal trends of current use pesticides in surface water and sediments and to determine its relation with hydrological stream dynamics within the agricultural watershed of El Crespo stream. We sampled two contrasting sites: Site 1 (upstream) surrounded by agricultural lands, and Site 2 (downstream) surrounded by natural grasslands. Most of the applied pesticides (i.e. glyphosate, 2,4-D, atrazine, tebuconazole and imidacloprid) were detected in high frequencies in surface water samples at both sites...
June 20, 2017: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/28630296/subunit-specific-role-for-the-amino-terminal-domain-of-ampa-receptors-in-synaptic-targeting
#6
Javier Díaz-Alonso, Yujiao J Sun, Adam J Granger, Jonathan M Levy, Sabine M Blankenship, Roger A Nicoll
The amino-terminal domain (ATD) of AMPA receptors (AMPARs) accounts for approximately 50% of the protein, yet its functional role, if any, remains a mystery. We have discovered that the translocation of surface GluA1, but not GluA2, AMPAR subunits to the synapse requires the ATD. GluA1A2 heteromers in which the ATD of GluA1 is absent fail to translocate, establishing a critical role of the ATD of GluA1. Inserting GFP into the ATD interferes with the constitutive synaptic trafficking of GluA1, but not GluA2, mimicking the deletion of the ATD...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28628388/coordination-of-ampa-receptor-trafficking-by-rab-small-gtpases
#7
Angelika Hausser, Katalin Schlett
Synaptic connections in the brain are continuously weakened or strengthened in response to changes in neuronal activity. This process, known as synaptic plasticity, is the cellular basis for learning and memory, and is thought to be altered in several neuronal disorders. An important aspect of synaptic plasticity is the tightly controlled trafficking and synaptic targeting of the AMPA-type glutamate receptors, which are the major mediators of fast excitatory transmission in the brain. This review addresses the role of Rab GTPases in AMPA receptor trafficking in neurons under basal conditions and during activity-induced synaptic plasticity, especially during long-term potentiation (LTP) and long-term depression (LTD)...
June 19, 2017: Small GTPases
https://www.readbyqxmd.com/read/28624414/corneal-kindled-c57bl-6-mice-exhibit-saturated-dentate-gyrus-long-term-potentiation-and-associated-memory-deficits-in-the-absence-of-overt-neuron-loss
#8
Gregory J Remigio, Jaycie L Loewen, Sage Heuston, Colin Helgeson, H Steve White, Karen S Wilcox, Peter J West
Memory deficits have a significant impact on the quality of life of patients with epilepsy and currently no effective treatments exist to mitigate this comorbidity. While these cognitive comorbidities can be associated with varying degrees of hippocampal cell death and hippocampal sclerosis, more subtle changes in hippocampal physiology independent of cell loss may underlie memory dysfunction in many epilepsy patients. Accordingly, animal models of epilepsy or epileptic processes exhibiting memory deficits in the absence of cell loss could facilitate novel therapy discovery...
June 15, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28624183/the-neuroprotective-effect-of-perampanel-in-lithium-pilocarpine-rat-seizure-model
#9
Ting Wu, Katsutoshi Ido, Yoshihide Osada, Sadaharu Kotani, Akira Tamaoka, Takahisa Hanada
PURPOSE: Status epilepticus (SE) causes irreversible neurodegeneration if not terminated quickly. Perampanel (PER), a potent AMPA receptor antagonist, has previously been shown to terminate seizures in the lithium-pilocarpine SE model. In the present study, we assessed whether PER would also prevent neuronal damage in this model. METHODS: SE was induced in rats using lithium chloride and pilocarpine. Initiation of SE was defined as continuous seizures that exhibited as rearing accompanied by bilateral forelimb clonus (Racine score 4)...
June 14, 2017: Epilepsy Research
https://www.readbyqxmd.com/read/28621434/eea1-restores-homeostatic-synaptic-plasticity-in-hippocampal-neurons-from-rett-syndrome-mice
#10
Xin Xu, Lucas Pozzo-Miller
Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). Deletion of Mecp2 in mice results in an imbalance of synaptic excitation and inhibition in hippocampal pyramidal neurons, which affects "Hebbian" long-term synaptic plasticity. Since the excitatory/inhibitory (E/I) balance is maintained by homeostatic mechanisms, we examined the role of MeCP2 in homeostatic synaptic plasticity (HSP) at excitatory synapses...
June 16, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28620858/toxicity-assessment-of-five-emerging-pollutants-alone-and-in-binary-or-ternary-mixtures-towards-three-aquatic-organisms
#11
Carole Di Poi, Katherine Costil, Valérie Bouchart, Marie-Pierre Halm-Lemeille
Despite a growing scientific attention on ecological impact of emerging pollutants (EPs) such as pharmaceuticals, personal care products, and pesticides, knowledge gaps remain regarding mixture toxicity and effects on aquatic organisms. Several EPs were screened in seawater (Normandy, France), and the ecotoxicity of five compounds, chosen on their occurrence in ecosystems and use worldwide, was assessed and were the biocides methylparaben (MP) and triclosan (TCS), a pesticide degradation product (AMPA), and the pharmaceuticals venlafaxine (VEN) and carbamazepine (CBZ)...
June 15, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28620737/analysis-of-bmaa-enantiomers-in-cycads-cyanobacteria-and-mammals-in-vivo-formation-and-toxicity-of-d-bmaa
#12
J S Metcalf, Doug Lobner, Sandra Anne Banack, Gregory A Cox, Peter B Nunn, Peter B Wyatt, Paul Alan Cox
Chronic dietary exposure to the cyanobacterial toxin β-N-methylamino-L-alanine (BMAA) triggers neuropathology in non-human primates, providing support for the theory that BMAA causes a fatal neurodegenerative illness among the indigenous Chamorro people of Guam. However, since there are two stereoisomers of BMAA, it is important to know if both can occur in nature, and if so, what role they might play in disease causation. As a first step, we analysed both BMAA enantiomers in cyanobacteria, cycads, and in mammals orally dosed with L-BMAA, to determine if enantiomeric changes could occur in vivo...
June 15, 2017: Amino Acids
https://www.readbyqxmd.com/read/28611594/overexpression-of-mineralocorticoid-receptors-in-the-mouse-forebrain-partly-alleviates-the-effects-of-chronic-early-life-stress-on-spatial-memory-neurogenesis-and-synaptic-function-in-the-dentate-gyrus
#13
Sofia Kanatsou, Henk Karst, Despoina Kortesidou, Rachelle A van den Akker, Jan den Blaauwen, Anjanette P Harris, Jonathan R Seckl, Harm J Krugers, Marian Joels
Evidence from human studies suggests that high expression of brain mineralocorticoid receptors (MR) may promote resilience against negative consequences of stress exposure, including childhood trauma. We examined, in mice, whether brain MR overexpression can alleviate the effects of chronic early life stress (ELS) on contextual memory formation under low and high stress conditions, and neurogenesis and synaptic function of dentate gyrus granular cells. Male mice were exposed to ELS by housing the dam with limited nesting and bedding material from postnatal day (PND) 2 to 9...
2017: Frontiers in Cellular Neuroscience
https://www.readbyqxmd.com/read/28609610/an-rna-aptamer-capable-of-forming-hydrogel-by-self-assembly
#14
Zhen Huang, Gagan N Kangovi, Wei Wen, Sangwoo Lee, Li Niu
Hydrogels are supramolecular assemblies with both solute transport properties like liquids and mechanical properties like elastomers. To date, every type of biomolecules, except ribonucleic acid (RNA), are capable of forming hydrogel. Here we report an RNA that forms hydrogel by self-assembly. This RNA is originally identified by systematic evolution of ligands by exponential enrichment (SELEX) to enhance the activity of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors as a potential RNA drug for treatment of cognitive disorders...
June 13, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28608780/signalling-through-ampa-receptors-on-oligodendrocyte-precursors-promotes-myelination-by-enhancing-oligodendrocyte-survival
#15
Eleni Kougioumtzidou, Takahiro Shimizu, Nicola B Hamilton, Koujiro Tohyama, Rolf Sprengel, Hannah Monyer, David Attwell, William D Richardson
Myelin, made by oligodendrocytes, is essential for rapid information transfer in the central nervous system. Oligodendrocyte precursors (OPs) receive glutamatergic synaptic input from axons but how this affects their development is unclear. Murine OPs in white matter express AMPA receptor (AMPAR) subunits GluA2, GluA3 and GluA4. We generated mice in which OPs lack both GluA2 and GluA3, or all three subunits GluA2/3/4, which respectively reduced or abolished AMPAR-mediated input to OPs. In both double- and triple-knockouts OP proliferation and number were unchanged but ~25% fewer oligodendrocytes survived in the subcortical white matter during development...
June 13, 2017: ELife
https://www.readbyqxmd.com/read/28606856/antinociceptive-effect-of-botulinum-toxin-a-involves-alterations-in-ampa-receptor-expression-and-glutamate-release-in-spinal-dorsal-horn-neurons
#16
Bin Hong, LingLing Yao, Linhui Ni, Li Wang, XingYue Hu
The use of botulinum toxin A (BTX-A) for various clinical therapeutic applications is increasing. It is widely believed that peripheral therapeutic or toxic effects of BTX-A are exclusively mediated by SNAP-25 cleavage. There is growing evidence of long-distance retrograde axonal transport of BTX-A on entering the central nervous system, subsequent to a local injection of the toxin. However, the prevalence of central antinociceptive effects after BTX-A peripheral application and its underlying mechanisms are unclear...
June 10, 2017: Neuroscience
https://www.readbyqxmd.com/read/28604739/autism-like-behaviours-and-enhanced-memory-formation-and-synaptic-plasticity-in-lrfn2-salm1-deficient-mice
#17
Naoko Morimura, Hiroki Yasuda, Kazuhiko Yamaguchi, Kei-Ichi Katayama, Minoru Hatayama, Naoko H Tomioka, Maya Odagawa, Akiko Kamiya, Yoshimi Iwayama, Motoko Maekawa, Kazuhiko Nakamura, Hideo Matsuzaki, Masatsugu Tsujii, Kazuyuki Yamada, Takeo Yoshikawa, Jun Aruga
Lrfn2/SALM1 is a PSD-95-interacting synapse adhesion molecule, and human LRFN2 is associated with learning disabilities. However its role in higher brain function and underlying mechanisms remain unknown. Here, we show that Lrfn2 knockout mice exhibit autism-like behavioural abnormalities, including social withdrawal, decreased vocal communications, increased stereotyped activities and prepulse inhibition deficits, together with enhanced learning and memory. In the hippocampus, the levels of synaptic PSD-95 and GluA1 are decreased...
June 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28603025/the-ampa-receptor-positive-allosteric-modulator-s-47445-rescues-in%C3%A2-vivo-ca3-ca1-long-term-potentiation-and-structural-synaptic-changes-in-old-mice
#18
Albert Giralt, María Ángeles Gómez-Climent, Rafael Alcalá, Sylvie Bretin, Daniel Bertrand, José María Delgado-García, Esther Pérez-Navarro, Jordi Alberch, Agnès Gruart
Positive allosteric modulators of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are small molecules that decrease deactivation of AMPARs via an allosteric site. These molecules keep the receptor in an active state. Interestingly, this type of modulator has been proposed for treating cognitive decline in ageing, dementias, and Alzheimer's disease (AD). S 47445 (8-cyclopropyl-3-[2-(3-fluorophenyl)ethyl]-7,8-dihydro-3H-[1,3]oxazino[6,5-g][1,2,3]benzotriazine-4,9-dione) is a novel AMPAR positive allosteric modulator (AMPA-PAM)...
June 8, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/28594440/calcium-signalling-in-medial-intercalated-cell-dendrites-and-spines
#19
Cornelia Strobel, Robert K P Sullivan, Peter Stratton, Pankaj Sah
The amygdala plays a central role in fear conditioning and extinction. The medial intercalated (mITC) neurons are GABAergic cell clusters interspaced between the basolateral (BLA) and central amygdala (CeA). These neurons are thought to play a key role in fear and extinction, controlling the output of the CeA by feed-forward inhibition. BLA to mITC cell inputs are though to undergo synaptic plasticity, a mechanism underlying learning, which is mediated by NMDA-receptor dependent mechanisms that require changes in cytosolic calcium...
June 8, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28591602/configurational-preference-of-the-glutamate-receptor-ligand-binding-domain-dimers
#20
Michael Yonkunas, Maiti Buddhadev, Jose C Flores Canales, Maria G Kurnikova
Ionotropic glutamate receptors are a family of tetrameric ion channels with functional states consisting of nonconducting, conducting, and desensitized states that are starting to become well characterized by electrophysiological and biophysical studies. However, the structure and relative energetics of these states beyond the general structure of the receptor are still not well understood. It is known that the interface between monomeric subunits of the tetramer plays a major role in distinguishing these functional states...
June 6, 2017: Biophysical Journal
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