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Tetrodotoxin

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https://www.readbyqxmd.com/read/27881722/maintenance-of-neuronal-size-gradient-in-mntb-requires-sound-evoked-activit
#1
Jessica H Weatherstone, Conny Kopp-Scheinpflug, Nadia Pilati, Yuan Wang, Ian D Forsythe, Edwin W Rubel, Bruce L Tempel
The medial nucleus of the trapezoid body (MNTB) is an important source of inhibition during the computation of sound location. It transmits fast and precisely timed action potentials at high frequencies; this requires an efficient calcium clearance mechanism, in which the plasma membrane calcium ATPase 2 (PMCA2) is a key component. Deafwaddler (dfw(2J)) mutant mice have a null mutation in PMCA2 causing deafness in homozygotes (dfw(2J)/dfw(2J)) and high frequency hearing loss in heterozygotes (+/dfw(2J)). Despite the deafness phenotype, no significant differences in MNTB volume or cell number were observed in dfw(2J) homozygous mutants, suggesting PMCA2 is not required for MNTB neuron survival...
November 23, 2016: Journal of Neurophysiology
https://www.readbyqxmd.com/read/27855599/a-highly-polar-phytocomplex-involving-rutin-is-responsible-for-the-neuromuscular-facilitation-caused-by-casearia-sylvestris-gua%C3%A3-atonga
#2
Yoshida Eh, Tribuiani N, Foramiglio Al, Foramiglio Ca, Tavares Rvs, Bonomini Tj, Bueno Pcp, Cavalheiro Aj, Hyslop S, Puebla P, San Feliciano A, Oshima-Franco Y
BACKGROUND: Of the various biological activities ascribed to extracts from Casearia sylvestris (guaçatonga), its facilitatory activity, i.e., ability to increase skeletal muscle contractile amplitude, has promising therapeutic applications. In this work, we investigated the components responsible for the previously described neurofacilitation caused by C. sylvestris leaves. METHODS: The methanolic fraction of C. sylvestris leaves was initially fractionated by column chromatography and partitioned in a MeOH:H2O gradient...
November 17, 2016: Current Pharmaceutical Biotechnology
https://www.readbyqxmd.com/read/27845057/tetrodotoxin-and-tributyltin-binding-abilities-of-recombinant-pufferfish-saxitoxin-and-tetrodotoxin-binding-proteins-of-takifugu-rubripes
#3
Hina Satone, Shohei Nonaka, Jae Man Lee, Yohei Shimasaki, Takahiro Kusakabe, Shun-Ichiro Kawabata, Yuji Oshima
We investigated the ability of recombinant pufferfish saxitoxin and tetrodotoxin binding protein types 1 and 2 of Takifugu rubripes (rTrub.PSTBP1 and rTrub.PSTBP2) to bind to tetrodotoxin (TTX) and tributyltin. Both rTrub.PSTBPs bound to tributyltin in an ultrafiltration binding assay but lost this ability on heat denaturation. In contrast, only rTrub.PSTBP2 bound to TTX even heat denaturation. This result suggests that the amino acid sequence of PSTBP2 may be contributed for its affinity for TTX.
November 11, 2016: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/27798943/effects-of-distigmine-on-electrical-field-stimulation-induced-contraction-of-mouse-urinary-bladder-smooth-muscles
#4
Keisuke Obara, Yurina Kobayashi, Daisuke Chino, Yoshio Tanaka
Distigmine bromide (distigmine), a reversible carbamate cholinesterase inhibitor, is used in Japan for treating detrusor underactivity, myasthenia gravis, and glaucoma. Although there is clinical evidence about the effectiveness of distigmine in the treatment of detrusor underactivity, mechanisms by which distigmine restores impaired urinary bladder smooth muscle (UBSM) contractility have not been fully investigated. The aims of this study were to investigate the potentiating effects of distigmine on UBSM contractions in response to parasympathetic nerve stimulation induced by electrical field stimulation (EFS) in mice...
November 1, 2016: Pharmacology
https://www.readbyqxmd.com/read/27793651/the-effect-of-inflammation-on-sympathetic-nerve-mediated-contractions-in-rat-isolated-caudal-artery
#5
Jocelyn Fotso Soh, Hilary R Strong, Noriko Daneshtalab, Reza Tabrizchi
Chronic inflammatory process(es) contributes to changes in vascular function in a variety of diseases. Sympathetic nerve-mediated responses in blood vessels play a pivotal role in regular physiological functions. We tested the hypothesis that sympathetic neuro-effector function will be altered as consequence of inflammatory state. Sympathetic nerve-mediated contractions and alpha adrenergic receptor expressions were evaluated in isolated caudal arteries of rats treated with saline and Complete Freund's adjuvant (CFA)...
October 25, 2016: European Journal of Pharmacology
https://www.readbyqxmd.com/read/27791149/cardiac-arrhythmia-in-a-mouse-model-of-sodium-channel-scn8a-epileptic-encephalopathy
#6
Chad R Frasier, Jacy L Wagnon, Yangyang Oliver Bao, Luke G McVeigh, Luis F Lopez-Santiago, Miriam H Meisler, Lori L Isom
: Patients with early infantile epileptic encephalopathy (EIEE) are at increased risk for sudden unexpected death in epilepsy (SUDEP). De novo mutations of the sodium channel gene SCN8A, encoding the sodium channel Nav1.6, result in EIEE13 (OMIM 614558), which has a 10% risk of SUDEP. Here, we investigated the cardiac phenotype of a mouse model expressing the gain of function EIEE13 patient mutation p.Asn1768Asp in Scn8a (Nav1.6-N1768D). We tested Scn8a(N1768D/+) mice for alterations in cardiac excitability...
October 26, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27780178/reduced-excitability-and-impaired-nociception-in-peripheral-unmyelinated-fibers-from-nav1-9-null-mice
#7
Tal Hoffmann, Katrin Kistner, Richard W Carr, Mohammed A Nassar, Peter W Reeh, Christian Weidner
The upregulation of the tetrodotoxin-resistant voltage-gated sodium channel NaV1.9 has previously been associated with inflammatory hyperalgesia. Na1.9 knockout (KO) mice, however, did not seem insensitive in conventional tests of acute nociception. Using electrophysiological, neurochemical, and behavioral techniques, we now show NaV1.9-null mice exhibit impaired mechanical and thermal sensory capacities and reduced electrical excitability of nociceptors. In single-fiber recordings from isolated skin, the electrical threshold of NaV1...
September 15, 2016: Pain
https://www.readbyqxmd.com/read/27765894/microrna-30b-regulates-expression-of-the-sodium-channel-nav1-7-in-nerve-injury-induced-neuropathic-pain-in-the-rat
#8
Jinping Shao, Jing Cao, Jiannan Wang, Xiuhua Ren, Songxue Su, Ming Li, Zhihua Li, Qingzan Zhao, Weidong Zang
Voltage-gated sodium channels, which are involved in pain pathways, have emerged as major targets for therapeutic intervention in pain disorders. Nav1.7, the tetrodotoxin-sensitive voltage-gated sodium channel isoform encoded by SCN9A and predominantly expressed in pain-sensing neurons in the dorsal root ganglion, plays a crucial role in nociception. MicroRNAs are highly conserved, small non-coding RNAs. Through binding to the 3' untranslated region of their target mRNAs, microRNAs induce the cleavage and/or inhibition of protein translation...
2016: Molecular Pain
https://www.readbyqxmd.com/read/27753838/sy-06-1-obesity-diabetes-and-hypertension-are-adipokines-responsible
#9
Anthony Heagerty
There is now a considerable body of evidence to suggest that the fat cells that surround blood vessels (perivascular adipose tissue, PVAT) can influence profoundly arterial tone by releasing vasodilator adipokines which can act locally in a paracrine fashion. In healthy lean individuals the primary vasodilator released appears to be adiponectin and there is a complex interation between autonomic nerve firing in PVAT and the release of nitric oxide from adipocytes and an increased bioavailability of adiponectin...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27741215/possible-mechanisms-of-hypothermia-after-inhibition-of-the-median-or-dorsal-raphe-nucleus-of-freely-moving-rats
#10
Takayuki Ishiwata, Arisa Oshimoto, Takehito Saito, Yasunori Kotani, Shigeki Nomoto, Yasutsugu Aihara, Hiroshi Hasegawa, Benjamin N Greenwood
We previously reported that tetrodotoxin (TTX) perfusion into the median raphe nucleus (MRN), which contains the cell bodies of serotonin (5-HT) neurons, induced a considerable body temperature reduction under normal and low ambient temperatures (23 and 5°C, respectively) in freely moving rats but showed no such effect under high ambient temperature (35°C). In the present study, we aimed to determine the mechanism(s) of body temperature reduction after TTX perfusion into the MRN by measuring tail skin temperature (an index of heat loss), heart rate (an index of heat production), and locomotor activity (Act) under normal ambient temperature (23°C)...
October 12, 2016: Neuroreport
https://www.readbyqxmd.com/read/27735854/effects-of-food-components-that-activate-trpa1-receptors-on-mucosal-ion-transport-in-the-mouse-intestine
#11
Linda J Fothergill, Brid Callaghan, Leni R Rivera, TinaMarie Lieu, Daniel P Poole, Hyun-Jung Cho, David M Bravo, John B Furness
TRPA1 is a ligand-activated cation channel found in the intestine and other tissues. Components of food that stimulate TRPA1 receptors (phytonutrients) include allyl isothiocyanate, cinnamaldehyde and linalool, but these may also act at other receptors. Cells lining the intestinal mucosa are immunoreactive for TRPA1 and Trpa1 mRNA occurs in mucosal extracts, suggesting that the TRPA1 receptor is the target for these agonists. However, in situ hybridisation reveals Trpa1 expression in 5-HT containing enteroendocrine cells, not enterocytes...
October 10, 2016: Nutrients
https://www.readbyqxmd.com/read/27728785/tetrodotoxin
#12
Max N Lorentz, Amber N Stokes, Daniela C Rößler, Stefan Lötters
In this Quick Guide, Lorentz et al. discuss the function of tetrodotoxin and its distribution in the animal kingdom.
October 10, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27698887/effects-of-hedera-helix-l-extracts-on-rat-prostate-cancer-cell-proliferation-and-motility
#13
Hatice Gumushan-Aktas, Seyhan Altun
Hedera helix L., a member of Araliaceae family, has antiproliferative, cytotoxic, antimicrobial, antifungal, antiprotozoal and anti-inflammatory effects, and is used in cosmetics. The aim of the present study was to investigate the effect of treatment with extracts of leaves and unripened fruits of H. helix on rat prostate cancer cell lines with markedly different metastatic potentials: Mat-LyLu cells (strongly metastatic) and AT-2 cells (weakly metastatic). The effects of the extracts on cell kinetics and migration were determined...
October 2016: Oncology Letters
https://www.readbyqxmd.com/read/27697698/characterization-of-brevetoxin-pbtx-3-exposure-in-neurons-of-the-anoxia-tolerant-freshwater-turtle-trachemys-scripta
#14
Courtney C Cocilova, Sarah L Milton
Harmful algal blooms are increasing in frequency and extent worldwide and occur nearly annually off the west coast of Florida where they affect both humans and wildlife. The dinoflagellate Karenia brevis is a key organism in Florida red tides that produces a suite of potent neurotoxins collectively referred to as the brevetoxins (PbTx). Brevetoxins bind to and open voltage gated sodium channels (VGSC), increasing cell permeability in excitable cells and depolarizing nerve and muscle tissue. Exposed animals may thus show muscular and neurological symptoms including head bobbing, muscle twitching, paralysis, and coma; large HABs can result in significant morbidity and mortality of marine life, including fish, birds, marine mammals, and sea turtles...
September 28, 2016: Aquatic Toxicology
https://www.readbyqxmd.com/read/27667511/phenolic-acids-isolated-from-the-fungus-schizophyllum-commune-exert-analgesic-activity-by-inhibiting-voltage-gated-sodium-channels
#15
Hui-Min Yao, Gan Wang, Ya-Ping Liu, Ming-Qiang Rong, Chuan-Bin Shen, Xiu-Wen Yan, Xiao-Dong Luo, Ren Lai
The present study was designed to search for compounds with analgesic activity from the Schizophyllum commune (SC), which is widely consumed as edible and medicinal mushroom world. Thin layer chromatography (TLC), tosilica gel column chromatography, sephadex LH 20, and reverse-phase high performance liquid chromatography (RP-HPLC) were used to isolate and purify compounds from SC. Structural analysis of the isolated compounds was based on nuclear magnetic resonance (NMR). The effects of these compounds on voltage-gated sodium (NaV) channels were evaluated using patch clamp...
September 2016: Chinese Journal of Natural Medicines
https://www.readbyqxmd.com/read/27665102/intracellular-calcium-oscillations-in-strongly-metastatic-human-breast-and-prostate-cancer-cells-control-by-voltage-gated-sodium-channel-activity
#16
Nahit Rizaner, Rustem Onkal, Scott P Fraser, Alessandro Pristerá, Kenji Okuse, Mustafa B A Djamgoz
The possible association of intracellular Ca(2+) with metastasis in human cancer cells is poorly understood. We have studied Ca(2+) signaling in human prostate and breast cancer cell lines of strongly versus weakly metastatic potential in a comparative approach. Intracellular free Ca(2+) was measured using a membrane-permeant fluorescent Ca(2+)-indicator dye (Fluo-4 AM) and confocal microscopy. Spontaneous Ca(2+) oscillations were observed in a proportion of strongly metastatic human prostate and breast cancer cells (PC-3M and MDA-MB-231, respectively)...
October 2016: European Biophysics Journal: EBJ
https://www.readbyqxmd.com/read/27662433/high-resolution-mass-spectrometry-analysis-of-tetrodotoxin-ttx-and-its-analogues-in-puffer-fish-and-shellfish
#17
Vaishali Bane, Brid Brosnan, Paul Barnes, Mary Lehane, Ambrose Furey
Tetrodotoxin (TTX) is an emerging toxin in the European marine environment. It has various known structural analogues. It acts as a sodium channel blocker; the ability of each analogue to bind to the sodium channel varies with the particular structure of each analogue. Thus, each analogue will vary in its toxic potential. TTX analogues co-occur in food samples at variable concentrations. An LC-MS method was developed for the identification and quantitation of several analogues of TTX using an LTQ-Orbitrap XL mass spectrometer...
September 2016: Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment
https://www.readbyqxmd.com/read/27650674/3-hz-subthreshold-oscillations-of-ca2-neurons-in-vivo
#18
Nobuyoshi Matsumoto, Kazuki Okamoto, Yuki Takagi, Yuji Ikegaya
The CA2 region is unique in the hippocampus; it receives direct synaptic innervations from several hypothalamic nuclei and expresses various receptors of neuromodulators, including adenosine, vasopressin, and oxytocin. Furthermore, the CA2 region may have distinct brain functions, such as the control of instinctive and social behaviors; however, little is known about the dynamics of the subthreshold membrane potentials of CA2 neurons in vivo. We conducted whole-cell current-clamp recordings from CA2 pyramidal cells in urethane-anesthetized mice and monitored the intrinsic fluctuations in their membrane potentials...
December 2016: Hippocampus
https://www.readbyqxmd.com/read/27642933/sy-06-1-obesity-diabetes-and-hypertension-are-adipokines-responsible
#19
Anthony Heagerty
There is now a considerable body of evidence to suggest that the fat cells that surround blood vessels (perivascular adipose tissue, PVAT) can influence profoundly arterial tone by releasing vasodilator adipokines which can act locally in a paracrine fashion. In healthy lean individuals the primary vasodilator released appears to be adiponectin and there is a complex interation between autonomic nerve firing in PVAT and the release of nitric oxide from adipocytes and an increased bioavailability of adiponectin...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27639809/acid-modulation-of-tetrodotoxin-sensitive-na-channels-in-large-sized-trigeminal-ganglion-neurons
#20
Michiko Nakamura, Do-Yeon Kim, Il-Sung Jang
Voltage-gated Na(+) channels in primary afferent neurons can be divided into tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na(+) channels. Although previous studies have shown the acid modulation of TTX-R Na(+) channels, the effect of acidic pH on tetrodotoxin-sensitive (TTX-S) Na(+) channels is still unknown. Here we report the effect of acidic pH on TTX-S Na(+) channels expressed in large-sized trigeminal ganglion (TG) neurons using a whole-cell patch clamp technique. The application of acidic extracellular solution decreased the peak amplitude of TTX-S currents (INa) in a pH-dependent manner, but weak acid (≥pH 6...
September 14, 2016: Brain Research
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