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https://www.readbyqxmd.com/read/29027912/guanidinium-toxins-and-their-interactions-with-voltage-gated-sodium-ion-channels
#1
REVIEW
Lorena M Durán-Riveroll, Allan D Cembella
Guanidinium toxins, such as saxitoxin (STX), tetrodotoxin (TTX) and their analogs, are naturally occurring alkaloids with divergent evolutionary origins and biogeographical distribution, but which share the common chemical feature of guanidinium moieties. These guanidinium groups confer high biological activity with high affinity and ion flux blockage capacity for voltage-gated sodium channels (NaV). Members of the STX group, known collectively as paralytic shellfish toxins (PSTs), are produced among three genera of marine dinoflagellates and about a dozen genera of primarily freshwater or brackish water cyanobacteria...
October 13, 2017: Marine Drugs
https://www.readbyqxmd.com/read/29023717/recovery-from-the-anatomical-effects-of-long-term-monocular-deprivation-in-cat-lateral-geniculate-nucleus
#2
Kevin R Duffy, Ming-Fai Fong, Donald E Mitchell, Mark F Bear
Monocular deprivation (MD) imposed early in postnatal life elicits profound structural and functional abnormalities throughout the primary visual pathway. The ability of MD to modify neurons within the visual system is restricted to a so-called critical period that, for cats, peaks at about one postnatal month and declines thereafter so that by about 3 months of age MD has little effect. Recovery from the consequences of MD likewise adheres to a critical period that ends by about 3 months of age, after which the effects of deprivation are thought to be permanent and without capacity for reversal...
October 11, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28972567/the-influence-of-resiniferatoxin-rtx-and-tetrodotoxin-ttx-on-the-distribution-relative-frequency-and-chemical-coding-of-noradrenergic-and-cholinergic-nerve-fibers-supplying-the-porcine-urinary-bladder-wall
#3
Ewa Lepiarczyk, Agnieszka Bossowska, Jerzy Kaleczyc, Agnieszka Skowrońska, Marta Majewska, Michal Majewski, Mariusz Majewski
The present study investigated the influence of intravesically instilled resiniferatoxin (RTX) or tetrodotoxin (TTX) on the distribution, number, and chemical coding of noradrenergic and cholinergic nerve fibers (NF) supplying the urinary bladder in female pigs. Samples from the bladder wall were processed for double-labelling immunofluorescence with antibodies against cholinergic and noradrenergic markers and some other neurotransmitter substances. Both RTX and TTX caused a significant decrease in the number of cholinergic NF in the urinary bladder wall (in the muscle coat, submucosa, and beneath the urothelium)...
October 3, 2017: Toxins
https://www.readbyqxmd.com/read/28971840/selective-inhibition-of-physiological-late-sodium-current-stabilizes-ventricular-repolarization
#4
Nesrine El-Bizri, Cindy Hong Li, Gong-Xin Liu, Sridharan Rajamani, Luiz Belardinelli
BACKGROUND: The physiological role of cardiac late Na+ current (INa) has not been well described. In this study, we tested the hypothesis that selective inhibition of physiological late INa abbreviates the normal action potential duration (APD) and counteracts the prolongation of APD and arrhythmic activities caused by inhibition of delayed rectifier K+ current, IKr. METHODS: The effects of GS-458967 (GS967) on the physiological late INa and action potentials (APs) in rabbit isolated ventricular myocytes and on the monophasic APs (MAPs) and arrhythmias in rabbit isolated perfused hearts were determined...
September 29, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28966065/involvement-of-neuronal-and-glial-activities-in-control-of-the-extracellular-d-serine-concentrations-by-the-ampa-glutamate-receptor-in-the-mouse-medial-prefrontal-cortex
#5
Sayuri Ishiwata, Asami Umino, Toru Nishikawa
It has been well accepted that d-serine may be an exclusive endogenous coagonist for the N-methyl-d-aspartate (NMDA)-type glutamate receptor in mammalian forebrain regions. We have recently found by using an in vivo dialysis method that an intra-medial prefrontal cortex infusion of S-α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (S-AMPA), a selective AMPA-type glutamate receptor agonist, causes a reduction in the extracellular levels of d-serine in a calcium-permeable AMPA receptor antagonist-sensitive manner...
September 28, 2017: Neurochemistry International
https://www.readbyqxmd.com/read/28938466/optogenetic-analysis-of-depolarization-dependent-glucagonlike-peptide-1-release
#6
Catalin Chimerel, Cristian Riccio, Keir Murison, Fiona M Gribble, Frank Reimann
Incretin hormones play an important role in the regulation of food intake and glucose homeostasis. Glucagonlike peptide-1 (GLP-1)-secreting cells have been demonstrated to be electrically excitable and to fire action potentials (APs) with increased frequency in response to nutrient exposure. However, nutrients can also be metabolized or activate G-protein-coupled receptors, thus potentially stimulating GLP-1 secretion independent of their effects on the plasma membrane potential. Here we used channelrhodopsins to manipulate the membrane potential of GLUTag cells, a well-established model of GLP-1-secreting enteroendocrine L cells...
October 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28934203/development-of-rat-female-genital-cortex-and-control-of-female-puberty-by-sexual-touch
#7
Constanze Lenschow, Johanna Sigl-Glöckner, Michael Brecht
Rat somatosensory cortex contains a large sexually monomorphic genital representation. Genital cortex undergoes an unusual 2-fold expansion during puberty. Here, we investigate genital cortex development and female rat sexual maturation. Ovariectomies and estradiol injections suggested sex hormones cause the pubertal genital cortex expansion but not its maintenance at adult size. Genital cortex expanded by thalamic afferents invading surrounding dysgranular cortex. Genital touch was a dominant factor driving female sexual maturation...
September 2017: PLoS Biology
https://www.readbyqxmd.com/read/28917804/development-and-validation-of-a-maleimide-based-enzyme-linked-immunosorbent-assay-for-the-detection-of-tetrodotoxin-in-oysters-and-mussels
#8
Laia Reverté, Maria Rambla-Alegre, Sandra Leonardo, Carlos Bellés, Katrina Campbell, Christopher T Elliott, Arjen Gerssen, Mirjam D Klijnstra, Jorge Diogène, Mònica Campàs
The recent detection of tetrodotoxins (TTXs) in puffer fish and shellfish in Europe highlights the necessity to monitor the levels of TTXs in seafood by rapid, specific, sensitive and reliable methods in order to protect human consumers. A previous immunoassay for TTX detection in puffer fish, based on the use of self-assembled monolayers (SAMs) for the immobilization of TTX on maleimide plates (mELISA), has been modified and adapted to the analysis of oyster and mussel samples. Changing dithiol for cysteamine-based SAMs enabled reductions in the assay time and cost, while maintaining the sensitivity of the assay...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28917752/facilely-self-assembled-magnetic-nanoparticles-aptamer-carbon-dots-nanocomposites-for-highly-sensitive-up-conversion-fluorescence-turn-on-detection-of-tetrodotoxin
#9
Hui Jin, Rijun Gui, Jie Sun, Yanfeng Wang
In this work, magnetic Fe3O4 nanoparticles (NPs) were modified with aptamer of tetrodotoxin (TTX) to form Fe3O4/aptamer complex. The self-assembling of carbon dots (CDs) and the aptamer generated Fe3O4/aptamer/CDs nanocomposites. The nanocomposites exhibited down-conversion fluorescence and up-conversion fluorescence (UCF) emissions simultaneously. When excited at a wavelength of 780nm, the UCF (peaked at 475nm) of nanocomposites increased regularly with the increase of TTX concentration [TTX]. In the [TTX] range from 0...
January 1, 2018: Talanta
https://www.readbyqxmd.com/read/28915947/immunosensor-array-platforms-based-on-self-assembled-dithiols-for-the-electrochemical-detection-of-tetrodotoxins-in-puffer-fish
#10
Laia Reverté, Katrina Campbell, Maria Rambla-Alegre, Christopher T Elliott, Jorge Diogène, Mònica Campàs
The recent detection of tetrodotoxins (TTXs) in European fish and shellfish has emphasized the urgent need to develop specific, selective, rapid and easy-to-use methods for their detection to assess the potential risk posed to human health. For this purpose, a dithiol self-assembled monolayer (SAM)-based immunoassay previously performed on maleimide plates (mELISA) has been adapted to gold electrode arrays for the development of an electrochemical immunosensor for TTX. The electrochemical SAM-based immunosensor designed herein, provided an oriented, stable and spaced sensing platform for the determination of TTX, attaining a limit of detection of 2...
October 9, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28915149/bulleyaconitine-a-preferably-reduces-tetrodotoxin-sensitive-sodium-current-in-uninjured-dorsal-root-ganglion-neurons-of-neuropathic-rats-probably-via-inhibition-of-protein-kinase-c
#11
Man-Xiu Xie, Rui-Ping Pang, Jie Yang, Kai-Feng Shen, Jing Xu, Xiong-Xiong Zhong, Shao-Kun Wang, Xiao-Long Zhang, Yan-Qing Liu, Xian-Guo Liu
Oral Bulleyaconitine A (BLA) is effective for treating neuropathic pain in human patients, but the underlying mechanism is poorly understood. Here, we tested whether BLA blocked voltage-gated sodium channels (VGSCs) in dorsal root ganglion (DRG) neurons. Compelling evidence shows that voltage-gated sodium channels are upregulated in uninjured DRG neurons but downregulated in injured ones following peripheral nerve injury. We found that BLA preferably inhibited Na currents in uninjured DRG neurons in neuropathic rats...
November 2017: Pain
https://www.readbyqxmd.com/read/28910154/activation-of-veratridine-sensitive-sodium-channels-but-not-electrical-field-stimulation-dilates-porcine-retinal-arterioles-with-preserved-perivascular-tissue
#12
Nils M Kratholm, Peter Skov Jensen, Sidse Kringelholt, Ulf Simonsen, Toke Bek
PURPOSE: Disturbances in retinal blood flow are a prominent feature of vision threatening retinal diseases. The regulation of tone in retinal resistance vessels involves the perivascular retinal tissue, but it is unknown to what extent neurons or glial cells contribute to the effect. Therefore, the purpose of the present study was to study the contribution of neurons in the perivascular retina to vascular tone during activation of voltage-gated sodium channels with veratridine and electrical field stimulation (EFS)...
September 14, 2017: Current Eye Research
https://www.readbyqxmd.com/read/28877214/direct-versus-indirect-actions-of-ghrelin-on-hypothalamic-npy-neurons
#13
Hiroshi Hashiguchi, Zhenyu Sheng, Vanessa Routh, Volodymyr Gerzanich, J Marc Simard, Joseph Bryan
OBJECTIVES: Assess direct versus indirect action(s) of ghrelin on hypothalamic NPY neurons. MATERIALS AND METHODS: Electrophysiology was used to measure ion channel activity in NPY-GFP neurons in slice preparations. Ca2+ imaging was used to monitor ghrelin activation of isolated NPY GFP-labeled neurons. Immunohistochemistry was used to localize Trpm4, SUR1 and Kir6.2 in the hypothalamus. RESULTS: Acylated ghrelin depolarized the membrane potential (MP) of NPY-GFP neurons in brain slices...
2017: PloS One
https://www.readbyqxmd.com/read/28871176/interleukin-17a-is-involved-in-mechanical-hyperalgesia-but-not-in-the-severity-of-murine-antigen-induced-arthritis
#14
Matthias Ebbinghaus, Gabriel Natura, Gisela Segond von Banchet, Susanne Hensellek, Martin Böttcher, Birgit Hoffmann, Firas Subhi Salah, Mieczyslaw Gajda, Thomas Kamradt, Hans-Georg Schaible
Interleukin-17A (IL-17A) is considered an important pro-inflammatory cytokine but its importance in joint diseases such as rheumatoid arthritis (RA) is unclear. It has also been reported that IL-17A may induce pain but it is unclear whether pro-inflammatory and pro-nociceptive effects are linked. Here we studied in wild type (WT) and IL-17A knockout (IL-17AKO) mice inflammation and hyperalgesia in antigen-induced arthritis (AIA). We found that the severity and time course of AIA were indistinguishable in WT and IL-17AKO mice...
September 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28867800/ciguatoxins-evoke-potent-cgrp-release-by-activation-of-voltage-gated-sodium-channel-subtypes-nav1-9-nav1-7-and-nav1-1
#15
Filip Touska, Simon Sattler, Philipp Malsch, Richard J Lewis, Peter W Reeh, Katharina Zimmermann
Ciguatoxins (CTXs) are marine toxins that cause ciguatera fish poisoning, a debilitating disease dominated by sensory and neurological disturbances that include cold allodynia and various painful symptoms as well as long-lasting pruritus. Although CTXs are known as the most potent mammalian sodium channel activator toxins, the etiology of many of its neurosensory symptoms remains unresolved. We recently described that local application of 1 nM Pacific Ciguatoxin-1 (P-CTX-1) into the skin of human subjects induces a long-lasting, painful axon reflex flare and that CTXs are particularly effective in releasing calcitonin-gene related peptide (CGRP) from nerve terminals...
August 30, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28867772/detection-of-tetrodotoxin-shellfish-poisoning-tsp-toxins-and-causative-factors-in-bivalve-molluscs-from-the-uk
#16
Andrew D Turner, Monika Dhanji-Rapkova, Lewis Coates, Lesley Bickerstaff, Steve Milligan, Alison O'Neill, Dermot Faulkner, Hugh McEneny, Craig Baker-Austin, David N Lees, Myriam Algoet
Tetrodotoxins (TTXs) are traditionally associated with the occurrence of tropical Pufferfish Poisoning. In recent years, however, TTXs have been identified in European bivalve mollusc shellfish, resulting in the need to assess prevalence and risk to shellfish consumers. Following the previous identification of TTXs in shellfish from southern England, this study was designed to assess the wider prevalence of TTXs in shellfish from around the coast of the UK. Samples were collected between 2014 and 2016 and subjected to analysis using HILIC-MS/MS...
August 30, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28860087/pro-excitatory-alterations-in-sodium-channel-activity-facilitate-subiculum-neuron-hyperexcitability-in-temporal-lobe-epilepsy
#17
Bryan S Barker, Aradhya Nigam, Matteo Ottolini, Ronald P Gaykema, Nicholas J Hargus, Manoj K Patel
Temporal lobe epilepsy (TLE) is a common form of adult epilepsy involving the limbic structures of the temporal lobe. Subiculum neurons act to provide a major output from the hippocampus and consist of a large population of endogenously bursting excitatory neurons. In TLE, subiculum neurons are largely spared, become hyperexcitable and show spontaneous epileptiform activity. The basis for this hyperexcitability is unclear, but is likely to involve alterations in the expression levels and function of various ion channels...
August 30, 2017: Neurobiology of Disease
https://www.readbyqxmd.com/read/28856239/histone-hypervariants-h2a-z-1-and-h2a-z-2-play-independent-and-context-specific-roles-in-neuronal-activity-induced-transcription-of-arc-arg3-1-and-other-immediate-early-genes
#18
Carissa J Dunn, Pushpita Sarkar, Emma R Bailey, Shannon Farris, Meilan Zhao, James M Ward, Serena M Dudek, Ramendra N Saha
The histone variant H2A.Z is an essential and conserved regulator of eukaryotic gene transcription. However, the exact role of this histone in the transcriptional process remains perplexing. In vertebrates, H2A.Z has two hypervariants, H2A.Z.1 and H2A.Z.2, that have almost identical sequences except for three amino acid residues. Due to such similarity, functional specificity of these hypervariants in neurobiological processes, if any, remain largely unknown. In this study with dissociated rat cortical neurons, we asked if H2A...
July 2017: ENeuro
https://www.readbyqxmd.com/read/28856044/label-free-optical-detection-of-action-potential-in-mammalian-neurons
#19
Subrata Batabyal, Sarmishtha Satpathy, Loan Bui, Young-Tae Kim, Samarendra Mohanty, Robert Bachoo, Digant P Davé
We describe an optical technique for label-free detection of the action potential in cultured mammalian neurons. Induced morphological changes due to action potential propagation in neurons are optically interrogated with a phase sensitive interferometric technique. Optical recordings composed of signal pulses mirror the electrical spike train activity of individual neurons in a network. The optical pulses are transient nanoscale oscillatory changes in the optical path length of varying peak magnitude and temporal width...
August 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28853553/highly-functionalized-tricyclic-oxazinanones-via-pairwise-oxidative-dearomatization-and-n-hydroxycarbamate-dehydrogenation-molecular-diversity-inspired-by-tetrodotoxin
#20
Steffen N Good, Robert J Sharpe, Jeffrey S Johnson
Benzenoids in principle represent attractive and abundant starting materials for the preparation of substituted cyclohexanes; however, the synthetic tools available for overcoming the considerable aromatic energies inherent to these building blocks limit the available product types. In this paper, we demonstrate access to heretofore unknown heterotricyclic structures by leveraging oxidative dearomatization of 2-hydroxymethyl phenols with concurrent N-hydroxycarbamate dehydrogenation using a common oxidant. The pairwise-generated, mutually reactive species then participate in a second stage acylnitroso Diels-Alder cycloaddition...
September 13, 2017: Journal of the American Chemical Society
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