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Tetrodotoxin

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https://www.readbyqxmd.com/read/28098344/inhibition-of-oxytocin-and-vasopressin-neuron-activity-in-rat-hypothalamic-paraventricular-nucleus-by-relaxin-3-rxfp3-signalling
#1
Alan Kania, Anna Czerw, Agnieszka Grabowiecka, Camila de Ávila, Tomasz Blasiak, Zenon Rajfur, Marian H Lewandowski, Grzegorz Hess, Elena Timofeeva, Andrew L Gundlach, Anna Blasiak
KEY-POINTS: Relaxin-3 is a stress-responsive neuropeptide that acts at its cognate receptor, RXFP3, to alter behaviours including feeding. In this study, we have demonstrated a direct, RXFP3-dependent, inhibitory action of relaxin-3 on oxytocin and vasopressin PVN neuron electrical activity, a putative cellular mechanism of orexinergic actions of relaxin-3. We observed a Gαi/o -protein-dependent inhibitory influence of selective RXFP3 activation on PVN neuronal activity in vitro and demonstrated a direct action of RXFP3 activation on oxytocin and vasopressin PVN neurons, confirmed by their abundant expression of RXFP3 mRNA...
January 18, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28089920/g-protein-coupled-estrogen-receptor-mediated-non-genomic-facilitatory-effect-of-estrogen-on-cooling-induced-reduction-of-skin-blood-flow-in-mice
#2
Izumi Serizawa, Nozomi Iwasaki, Hirotake Ishida, Shin-Ya Saito, Tomohisa Ishikawa
An enhanced vasoconstrictor activity of cutaneous arteries participates in the reduction of skin blood flow induced by cooling stimulation. Raynaud's phenomenon, which is characterized by intense cooling-induced constriction of cutaneous arteries, is more common in women during the period from menarche to menopause. We thus investigated the effect of 17β-estradiol (E2) on cooling-induced reduction of plantar skin blood flow (PSBF) in mouse in vivo. Ovariectomized female ddY mice, anaesthetized with pentobarbital, were treated with tetrodotoxin for eliminating the sympathetic nerve tone and artificially ventilated...
January 12, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28088386/trypsin-induces-biphasic-muscle-contraction-and-relaxation-via-transient-receptor-potential-vanilloid-1-and-neurokinin-receptors-1-2-in-porcine-esophageal-body
#3
Bai Xiaopeng, Yoshimasa Tanaka, Eikichi Ihara, Katsuya Hirano, Kayoko Nakano, Mayumi Hirano, Yoshinao Oda, Kazuhiko Nakamura
Duodenal reflux of fluids containing trypsin relates to refractory gastroesophageal reflux disease (GERD). Esophageal peristalsis and clearance are important factors in GERD pathogenesis. However, the function of trypsin in esophageal body contractility is not fully understood. In this study, effects of trypsin on circular smooth muscle (CSM) and longitudinal smooth muscle (LSM) of the porcine esophageal body were examined. Trypsin elicited a concentration dependent biphasic response, a major contraction and a subsequent relaxation only in CSM...
January 11, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28079757/pathogenesis-of-abdominal-pain-in-bowel-obstruction-role-of-mechanical-stress-induced-upregulation-of-nerve-growth-factor-in-gut-smooth-muscle-cells
#4
You-Min Lin, Yu Fu, John Winston, Ravi Radhakrishnan, Sushil K Sarna, Li-Yen M Huang, Xuan-Zheng Shi
Abdominal pain is one of the major symptoms in bowel obstruction (BO); its cellular mechanisms remain incompletely understood. We tested the hypothesis that mechanical stress in obstruction upregulates expression of nociception mediator nerve growth factor (NGF) in gut smooth muscle cells (SMC), and NGF sensitizes primary sensory nerve to contribute to pain in BO. Partial colon obstruction was induced with a silicon band implanted in the distal bowel of Sprague-Dawley rats. Colon-projecting sensory neurons in the dorsal root ganglia (DRG, T13 to L2) were identified for patch clamp and gene expression studies...
January 6, 2017: Pain
https://www.readbyqxmd.com/read/28074621/total-synthesis-of-tetrodotoxin-and-11-norttx-6-r-ol
#5
Tomoaki Maehara, Keisuke Motoyama, Tatsuya Toma, Satoshi Yokoshima, Tohru Fukuyama
The enantioselective total synthesis of (-)-tetrodotoxin [(-)-TTX] and 4,9-anhydrotetrodotoxin, which are selective blockers of voltage-gated sodium channels, was accomplished from the commercially available p-benzoquinone. This synthesis was based on efficient stereocontrol of the six contiguous stereogenic centers on the core cyclohexane ring through Ogasawara's method, [3,3]-sigmatropic rearrangement of an allylic cyanate, and intramolecular 1,3-dipolar cycloaddition of a nitrile oxide. Our synthetic route was applied to the synthesis of the tetrodotoxin congeners 11-norTTX-6(R)-ol and 4,9-anhydro-11-norTTX-6(R)-ol through late-stage modification of the common intermediate...
January 11, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28074005/synergistic-regulation-of-serotonin-and-opioid-signaling-contributes-to-pain-insensitivity-in-nav1-7-knockout-mice
#6
Jörg Isensee, Leonhardt Krahé, Katharina Moeller, Vanessa Pereira, Jane E Sexton, Xiaohui Sun, Edward Emery, John N Wood, Tim Hucho
Genetic loss of the voltage-gated sodium channel Nav1.7 (Nav1.7(-/-)) results in lifelong insensitivity to pain in mice and humans. One underlying cause is an increase in the production of endogenous opioids in sensory neurons. We analyzed whether Nav1.7 deficiency altered nociceptive heterotrimeric guanine nucleotide-binding protein-coupled receptor (GPCR) signaling, such as initiated by GPCRs that respond to serotonin (pronociceptive) or opioids (antinociceptive), in sensory neurons. We found that the nociceptive neurons of Nav1...
January 10, 2017: Science Signaling
https://www.readbyqxmd.com/read/28066889/enteric-glial-activity-regulates-secretomotor-function-in-the-mouse-colon-but-does-not-acutely-affect-gut-permeability
#7
Vladimir Grubišić, Brian D Gulbransen
Enteric glial cells are often implicated in the regulation of epithelial barrier and secretomotor functions of the intestines. But whether glial cell activity regulates these functions acutely under physiological conditions is not clear. We addressed this issue by using transgenic animal models to modify the activity of enteric glia, either reducing glial expression of connexin 43 in Sox10::CreER(T2+/-) /Cx43(f/f) mice or activating glial calcium responses in GFAP::hM3Dq mice, and tested the effects on colonic barrier function and electrogenic ion transport in Ussing chambers...
January 8, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28058845/ultrasensitive-phototriggered-local-anesthesia
#8
Changyou Zhan, Weiping Wang, Claudia Santamaria, Bruce Wang, Alina Rwei, Brian P Timko, Daniel S Kohane
An injectable local anesthetic producing repeatable on-demand nerve block would be desirable for pain management. Here we present a phototriggerable device to achieve repeatable and adjustable on-demand local anesthesia in superficial or deep tissues, consisting of gold nanorods attached to low temperature sensitive liposomes (LTSL). The particles were loaded with tetrodotoxin and dexmedetomidine. Near-infrared light (NIR, 808 nm, continuous wave) could heat gold nanorods at low fluence (short duration and low irradiance), leading to rapid release of payload...
January 6, 2017: Nano Letters
https://www.readbyqxmd.com/read/28039790/degradation-photocatalysis-of-tetrodotoxin-as-a-poison-by-gold-doped-pdo-nanoparticles-supported-on-reduced-graphene-oxide-nanocomposites-and-evaluation-of-its-antibacterial-activity
#9
Ali Fakhri, Mahsa Naji
In this project, synthesis of pure and gold doped PdO-reduced graphene oxide nanocomposites by sonochemical and deposition-precipitation process was performed and characterized using X-ray diffraction (XRD), transmission electronic microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The specific surface area of synthesized un-doped and Au doped PdO-RGO nanocomposites is 83.2, 109.1m(2)g(-1) and total pore volume is 0.31, 0.40cm(3)g(-1), respectively. With Tetrodotoxin as a target pollutant, photocatalytic system of UV+photocatalyst+H2O2 was set up...
December 23, 2016: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28024908/hyp-17-a-novel-voltage-gated-sodium-channel-blocker-relieves-inflammatory-and-neuropathic-pain-in-rats
#10
Jee Youn Lee, Yoo Lim Kam, Jungae Oh, Dong Hyun Kim, Jin-Sung Choi, Hae Young Choi, Sungmin Han, Inchan Youn, Hea-Young Park Choo, Tae Young Yune
Clinical and experimental studies suggest that voltage-gated sodium channels (VGSCs) play a key role in the pathogenesis of neuropathic pain and that blocking agents against these channels can be potentially therapeutic. In the current study, we investigated whether a novel compound, (-)-2-Amino-1-(4-((4-chlorophenyl)(phenyl)methyl)piperazin-1-yl)-propan-1-one(HYP-17), binds to VGSCs and evaluated its inhibitory effect on Na(+) currents of the rat dorsal root ganglia (DRG) sensory neurons and its analgesic effect on inflammatory and neuropathic pain...
December 24, 2016: Pharmacology, Biochemistry, and Behavior
https://www.readbyqxmd.com/read/28018918/role-of-bkca-in-stretch-induced-relaxation-of-colonic-smooth-muscle
#11
Jie Ren, Fang Xin, Ping Liu, Hai-Yan Zhao, Si-Tao Zhang, Peng Han, Hai-Xia Huang, Wei Wang
Stretch-induced relaxation has not been clearly identified in gastrointestinal tract. The present study is to explore the role of large conductance calcium-activated potassium channels (BKCa) in stretch-induced relaxation of colon. The expression and currents of BKCa were detected and the basal muscle tone and contraction amplitude of colonic smooth muscle strips were measured. The expression of BKCa in colon is higher than other GI segments (P < 0.05). The density of BKCa currents was very high in colonic smooth muscle cells (SMCs)...
2016: BioMed Research International
https://www.readbyqxmd.com/read/28017670/presynaptic-facilitation-by-tetracaine-of-glutamatergic-spontaneous-excitatory-transmission-in-the-rat-spinal-substantia-gelatinosa-involvement-of-trpa1-channels
#12
Lian-Hua Piao, Tsugumi Fujita, Ting Yu, Eiichi Kumamoto
The amide-type local anesthetic (LA) lidocaine activates transient receptor potential (TRP) ankyrin-1 (TRPA1) channels to facilitate spontaneous L-glutamate release onto spinal substantia gelatinosa (SG) neurons, which play a crucial role in regulating nociceptive transmission. In contrast, the ester-type LA procaine reduces the spontaneous release of L-glutamate in SG neurons. In order to determine whether TRPA1 activation by LAs is specific to amide-types, we examined the actions of tetracaine, another ester-type LA, and other amide-type LAs on glutamatergic spontaneous excitatory transmission in SG neurons by focusing on TRP activation...
December 22, 2016: Brain Research
https://www.readbyqxmd.com/read/28011833/human-induced-pluripotent-stem-cell-derived-cardiomyocytes-from-cardiac-progenitor-cells-effects-of-selective-ion-channel-blockade
#13
Claudia Altomare, Enea Pianezzi, Elisabetta Cervio, Sara Bolis, Vanessa Biemmi, Patrizia Benzoni, Giovanni G Camici, Tiziano Moccetti, Lucio Barile, Giuseppe Vassalli
AIM: Human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes are likely to revolutionize electrophysiological approaches to arrhythmias. Recent evidence suggests the somatic cell origin of hiPSCs may influence their differentiation potential. Owing to their cardiomyogenic potential, cardiac-stromal progenitor cells (CPCs) are an interesting cellular source for generation of hiPSC-derived cardiomyocytes. The effect of ionic current blockade in hiPSC-derived cardiomyocytes generated from CPCs has not been characterized yet...
December 2016: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
https://www.readbyqxmd.com/read/27998617/biophysical-molecular-and-pharmacological-characterization-of-voltage-dependent-sodium-channels-from-induced-pluripotent-stem-cell-derived-cardiomyocytes
#14
Adrien Moreau, Aurélie Mercier, Olivier Thériault, Mohamed Boutjdir, Bettina Burger, Dagmar I Keller, Mohamed Chahine
BACKGROUND: The ability to differentiate patient-specific human induced pluripotent stem cells in cardiac myocytes (hiPSC-CM) offers novel perspectives for cardiovascular research. A number of studies, that reported mainly on current-voltage curves used hiPSC-CM to model voltage-gated Na(+) channel (Nav) dysfunction. However, the expression patterns and precise biophysical and pharmacological properties of Nav channels from hiPSC-CM remain unknown. Our objective was to study the characteristics of Nav channels from hiPSC-CM and assess the appropriateness of this novel cell model...
October 11, 2016: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/27975818/the-toxicity-of-ribbon-worms-alpha-nemertides-or-tetrodotoxin-or-both
#15
H S Andersson, E Jacobsson, C Eriksson, M Hedström, H Seth, P Sundberg, K J Rosengren, M Strand, U Göransson
No abstract text is available yet for this article.
December 2016: Planta Medica
https://www.readbyqxmd.com/read/27964993/laminin-is-instructive-and-calmodulin-dependent-kinase-ii-is-non-permissive-for-the-formation-of-complex-aggregates-of-acetylcholine-receptors-on-myotubes-in-culture
#16
Raphael Vezina-Audette, Mathieu Tremblay, Salvatore Carbonetto
Previous work has shown that myotubes cultured on laminin-coated substrates form complex aggregates of synaptic proteins that are similar in shape and composition to neuromuscular junctions (NMJs). Here we show that laminin instructs the location of complex aggregates which form only on the lower surface when laminin is coated onto culture dishes but over the entire cell when laminin is added in solution. Silencing of myotubes by agents that block electrical activity (tetrodotoxin, verapamil) or by inhibitors of calmodulin dependent kinase (CaMKII) render the myotube permissive for the formation of complex aggregates...
December 10, 2016: Matrix Biology: Journal of the International Society for Matrix Biology
https://www.readbyqxmd.com/read/27951505/corrigendum-to-development-and-validation-of-a-high-throughput-online-solid-phase-extraction-liquid-chromatography-tandem-mass-spectrometry-method-for-the-detection-of-tetrodotoxin-in-human-urine-toxicon-119-2016-64-71
#17
Rebecca Coleman, Sharon W Lemire, William Bragg, Alaine Garrett, Geovannie Ojeda-Torres, Elizabeth Hamelin, Rudolph C Johnson, Jerry Thomas
No abstract text is available yet for this article.
January 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/27923665/nicotine-enhances-gabaergic-inhibition-of-oxytocin-mrna-expressing-neuron-in-the-hypothalamic-paraventricular-nucleus-in-vitro-in-rats
#18
Ke-Min Zhang, Guo-Yan Zhao, Bin-Bin Zhang, Qi Xu, Chun-Ping Chu, Hua Jin, De-Lai Qiu
We recently found that extracellular administration of nicotine indirectly excited hypothalamic paraventricular nucleus (PVN) corticotropin-releasing hormone (CRH) mRNA-expressing neurons. In this study, we studied the effect of nicotine on PVN oxytocin (OT) mRNA-expressing neuron in vitro in rats, by whole-cell patch-clamp recording technique, immunohistochemistry methods and single-cell reverse-transcription multiplex polymerase chain reaction (SC-RT-mPCR) methods Our results showed that 79.3% (73/92) of the 92 PVN putative magnocellular neurons co-expressed GAPDH mRNA and OT mRNA...
December 5, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27915058/larger-rate-dependence-of-late-sodium-current-in-cardiac-purkinje-cells-a-potential-link-to-arrhythmogenesis
#19
Wei Li, Ying Yu, Jian-Wen Hou, Zhi-Wen Zhou, Kai Guo, Peng-Pai Zhang, Zhi-Quan Wang, Jian-Hua Yan, Jian Sun, Qing Zhou, Yue-Peng Wang, Yi-Gang Li
BACKGROUND: Purkinje cells (PCs) have a steeper rate dependence of repolarization and are more susceptible to arrhythmic activity than do ventricular myocytes (VMs). Late sodium current (INaL) is rate dependent and contributes to rate dependence of repolarization. OBJECTIVE: This study sought to test our hypothesis that PCs have a larger rate dependence of INaL, contributing to their steeper rate dependence of repolarization and higher susceptibility to arrhythmic activity, than do VMs...
December 1, 2016: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/27881722/maintenance-of-neuronal-size-gradient-in-mntb-requires-sound-evoked-activit
#20
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
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