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Tetrodotoxin

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https://www.readbyqxmd.com/read/28638222/corticotropin-releasing-factor-stimulates-colonic-motility-via-muscarinic-receptors-in-the-rat
#1
Kyung-Jo Kim, Ki Bae Kim, Soon Man Yoon, Joung-Ho Han, Hee Bok Chae, Seon Mee Park, Sei Jin Youn
AIM: To measure exogenous corticotropin-releasing factor (CRF)-induced motility of the isolated rat colon and to demonstrate the effect of pharmacologic inhibition on CRF-induced motility. METHODS: The isolated vascularly-perfused rat colon was used. Luminal pressure was monitored via microtip catheter pressure transducers in the proximal and distal colon. At first, exogenous CRF was administered in a stepwise manner and the concentration of CRF yielding maximal colonic motility was selected...
June 7, 2017: World Journal of Gastroenterology: WJG
https://www.readbyqxmd.com/read/28635651/effects-of-tetrodotoxin-in-mouse-models-of-visceral-pain
#2
Rafael González-Cano, Miguel Ángel Tejada, Antonia Artacho-Cordón, Francisco Rafael Nieto, José Manuel Entrena, John N Wood, Cruz Miguel Cendán
Visceral pain is very common and represents a major unmet clinical need for which current pharmacological treatments are often insufficient. Tetrodotoxin (TTX) is a potent neurotoxin that exerts analgesic actions in both humans and rodents under different somatic pain conditions, but its effect has been unexplored in visceral pain. Therefore, we tested the effects of systemic TTX in viscero-specific mouse models of chemical stimulation of the colon (intracolonic instillation of capsaicin and mustard oil) and intraperitoneal cyclophosphamide-induced cystitis...
June 21, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28634472/antifungal-activity-against-filamentous-fungi-of-ts1-a-multifunctional-toxin-from-tityus-serrulatus-scorpion-venom
#3
Welligton M Santussi, Karla C F Bordon, Ana P N Rodrigues Alves, Camila T Cologna, Suraia Said, Eliane C Arantes
Antimicrobial peptides (AMPs) are ubiquitous and multipotent components of the innate immune defense arsenal used by both prokaryotic and eukaryotic organisms. The search for new AMPs has increased in recent years, due to the growing development of microbial resistance to therapeutical drugs. In this work, we evaluate the effects of Tityus serrulatus venom (Tsv), its fractions and its major toxin Ts1, a beta-neurotoxin, on fungi growth. The fractions were obtained by ion-exchange chromatography of Tsv. The growth inhibition of 11 pathogenic and non-pathogenic filamentous fungi (Aspergillus fumigatus, A...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28623807/hiv-tat-excites-d1-receptor-like-expressing-neurons-from-rat-nucleus-accumbens
#4
G Cristina Brailoiu, Elena Deliu, Jeffrey L Barr, Linda M Console-Bram, Alexandra M Ciuciu, Mary E Abood, Ellen M Unterwald, Eugen Brailoiu
BACKGROUND: HIV-1 infection and drug abuse are frequently co-morbid and their association greatly increases the severity of HIV-1-induced neuropathology. While nucleus accumbens (NAcc) function is severely perturbed by drugs of abuse, little is known about how HIV-1 infection affects NAcc. METHODS: We used calcium and voltage imaging to investigate the effect of HIV-1 trans-activator of transcription (Tat) on rat NAcc. Based on previous neuronal studies, we hypothesized that Tat modulates intracellular Ca(2+) homeostasis of NAcc neurons...
June 8, 2017: Drug and Alcohol Dependence
https://www.readbyqxmd.com/read/28621434/eea1-restores-homeostatic-synaptic-plasticity-in-hippocampal-neurons-from-rett-syndrome-mice
#5
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/28605704/4-5-dichloro-2-octyl-4-isothiazolin-3-one-dcoit-modifies-synaptic-transmission-in-hippocampal-ca3-neurons-of-rats
#6
Masahito Wakita, Kiyomitsu Shoudai, Yasuo Oyama, Norio Akaike
4,5-Dichloro-2-octyl-4-isothiazolin-3-one (DCOIT) is an alternative to organotin antifoulants, such as tributyltin and triphenyltin. Since DCOIT is found in harbors, bays, and coastal areas worldwide, this chemical compound may have some impacts on ecosystems. To determine whether DCOIT possesses neurotoxic activity by modifying synaptic transmission, we examined the effects of DCOIT on synaptic transmission in a 'synaptic bouton' preparation of rat brain. DCOIT at concentrations of 0.03-1 μM increased the amplitudes of evoked synaptic currents mediated by GABA and glutamate, while it reduced the amplitudes of these currents at 3-10 μM...
May 29, 2017: Chemosphere
https://www.readbyqxmd.com/read/28596834/acute-cocaine-exposure-elicits-rises-in-calcium-in-arousal-related-laterodorsal-tegmental-neurons
#7
Mads Ødum Lambert, Theis Højland Ipsen, Kristi Anne Kohlmeier
Cocaine has strong reinforcing properties, which underlie its high addiction potential. Reinforcement of use of addictive drugs is associated with rises in dopamine (DA) in mesoaccumbal circuitry. Excitatory afferent input to mesoaccumbal circuitry sources from the laterodorsal tegmental nucleus (LDT). Chronic, systemic cocaine exposure has been shown to have cellular effects on LDT cells, but acute actions of local application have never been demonstrated. Using calcium imaging, we show that acute application of cocaine to mouse brain slices induces calcium spiking in cells of the LDT...
February 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28595006/selective-targeting-of-neurons-with-inorganic-nanoparticles-revealing-the-crucial-role-of-nanoparticle-surface-charge
#8
Silvia Dante, Alessia Petrelli, Enrica Maria Petrini, Roberto Marotta, Alessandro Maccione, Alessandro Alabastri, Alessandra Quarta, Francesco De Donato, Tiziana Ravasenga, Ayyappan Sathya, Roberto Cingolani, Remo Proietti Zaccaria, Luca Berdondini, Andrea Barberis, Teresa Pellegrino
Nanoparticles (NPs) are increasingly used in biomedical applications but the factors that influence their interactions with living cells need to be elucidated. Here, we reveal the role of NP surface charge in determining their neuronal interactions and electrical responses. We discovered that negatively charged NPs administered at low concentration (10nM) interact with the neuronal membrane and at the synaptic cleft, whereas positively- and neutrally-charged NPs never localize on neurons. This effect is shape and material independent...
June 8, 2017: ACS Nano
https://www.readbyqxmd.com/read/28591591/activation-of-sodium-channel-by-a-novel-%C3%AE-scorpion-toxin-bmk-nt2-stimulates-erk1-2-and-cerb-phosphorylation-through-a-ca-2-dependent-pathway-in-neocortical-neurons
#9
Xiaohan Zou, Ying Wu, Juan Chen, Fang Zhao, Fan Zhang, Boyang Yu, Zhengyu Cao
Neuronal excitability controls the expression of a variety of genes and proteins and therefore regulates neurite outgrowth and synapse formation, fundamental physiological processes controlling learning and memory. Scorpion venom contains many neurotoxins which alter ion channel activities that influence neuronal excitability. In this study, a novel scorpion peptide termed BmK NT2 was purified from venom of Chinese scorpion Buthus martensii Karsch by combining mass spectrum mapping and intracellular Ca(2+) concentration measurement in primary cultured neocortical neurons...
June 4, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28587910/evaluation-of-tetrodotoxins-in-puffer-fish-caught-along-the-mediterranean-coast-of-spain-toxin-profile-of-lagocephalus-sceleratus
#10
Maria Rambla-Alegre, Laia Reverté, Vanessa Del Río, Pablo de la Iglesia, Oscar Palacios, Cintia Flores, Josep Caixach, Katrina Campbell, Christopher T Elliott, Andrés Izquierdo-Muñoz, Mònica Campàs, Jorge Diogène
Although consumption of Tetraodontidae species is prohibited in the EU, intoxications are still reported. The evaluation of tetrodotoxins (TTXs) by mass spectrometry (LC-MS/MS and LC-HRMS) and a screening immunoassay (mELISA) in tetraodontid fishes caught along the Western Mediterranean Sea revealed high concentrations of TTXs in Lagocephalus sceleratus while no TTXs were identified in L. lagocephalus and Sphoeroides pachygaster individuals. The high TTXs content found in the L. sceleratus analysed herein demonstrate the occurrence of highly toxic puffer fish in the Western Mediterranean Sea...
June 3, 2017: Environmental Research
https://www.readbyqxmd.com/read/28580281/glucagon-like-peptide-2-promotes-gallbladder-refilling-via-a-tgr5-independent-glp-2r-dependent-pathway
#11
Bernardo Yusta, Dianne Matthews, Grace B Flock, John R Ussher, Brigitte Lavoie, Gary M Mawe, Daniel J Drucker
OBJECTIVE: Glucagon-like peptides (GLPs) are secreted from enteroendocrine cells in response to nutrients and bile acids and control metabolism via actions on structurally-related yet distinct G protein coupled receptors. GLP-1 regulates gut motility, appetite, islet function, and glucose homeostasis, whereas GLP-2 enhances intestinal nutrient absorption. GLP-1R agonists are used to treat diabetes and obesity, and a GLP-2R agonist is approved to treat short bowel syndrome. Unexpectedly, reports of gallbladder disease have been associated with the use of both GLP-1R and GLP-2R agonists and after bariatric surgery, although the mechanisms remain unknown...
June 2017: Molecular Metabolism
https://www.readbyqxmd.com/read/28579948/modulation-of-low-voltage-activated-inward-current-permeable-to-sodium-and-calcium-by-darpp-32-drives-spontaneous-firing-of-insect-octopaminergic-neurosecretory-cells
#12
Bruno Lapied, Antoine Defaix, Maria Stankiewicz, Eléonore Moreau, Valérie Raymond
Identification of the different intracellular pathways that control phosphorylation/dephosphorylation process of ionic channels represents an exciting alternative approach for studying the ionic mechanisms underlying neuronal pacemaker activity. In the central nervous system of the cockroach Periplaneta americana, octopaminergic neurons, called dorsal unpaired median (DUM; DUM neurons), generate spontaneous repetitive action potentials. Short-term cultured adult DUM neurons isolated from the terminal abdominal ganglion (TAG) of the nerve cord were used to study the regulation of a tetrodotoxin-sensitive low-voltage-activated (LVA) channel permeable to sodium and calcium (Na/Ca), under whole cell voltage- and current-clamp conditions...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28574462/a-study-of-11-%C3%A2-h-tetrodotoxin-absorption-distribution-metabolism-and-excretion-adme-in-adult-sprague-dawley-rats
#13
Bihong Hong, Hui Chen, Jiacai Han, Quanling Xie, Jianlin He, Kaikai Bai, Yanming Dong, Ruizao Yi
Tetrodotoxin (TTX) is a powerful sodium channel blocker that in low doses can safely relieve severe pain. Studying the absorption, distribution, metabolism and excretion (ADME) of TTX is challenging given the extremely low lethal dose. We conducted radiolabeled ADME studies in Sprague-Dawley rats. After a single dose of 6 μg/(16 μCi/kg) 11-[³H]TTX, pharmacokinetics of plasma total radioactivity were similar in male and female rats. Maximum radioactivity (5.56 ng Eq./mL) was reached in 10 min. [³H]TTX was below detection in plasma after 24 h...
June 2, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28560448/multiple-nav1-5-isoforms-are-functionally-expressed-in-the-brain-and-present-distinct-expression-patterns-compared-with-cardiac-nav1-5
#14
Jun Wang, Shao-Wu Ou, Yun-Fei Bai, Yun-Jie Wang, Zhi-Qing David Xu, Guo-Ming Luan
It has previously been demonstrated that there are various voltage gated sodium channel (Nav) 1.5 splice variants expressed in brain tissue. A total of nine Nav1.5 isoforms have been identified, however, the potential presence of further Nav1.5 variants expressed in brain neurons remains to be elucidated. The present study systematically investigated the expression of various Nav1.5 splice variants and their associated electrophysiological properties in the rat brain tissue, via biochemical analyses and whole‑cell patch clamp recording...
July 2017: Molecular Medicine Reports
https://www.readbyqxmd.com/read/28560313/urothelial-tight-junction-barrier-dysfunction-sensitizes-bladder-afferents
#15
Nicolas Montalbetti, Anna C Rued, Stefanie N Taiclet, Lori A Birder, F Aura Kullmann, Marcelo D Carattino
Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic voiding disorder that presents with pain in the urinary bladder and surrounding pelvic region. A growing body of evidence suggests that an increase in the permeability of the urothelium, the epithelial barrier that lines the interior of the bladder, contributes to the symptoms of IC/BPS. To examine the consequence of increased urothelial permeability on pelvic pain and afferent excitability, we overexpressed in the urothelium claudin 2 (Cldn2), a tight junction (TJ)-associated protein whose message is significantly upregulated in biopsies of IC/BPS patients...
May 2017: ENeuro
https://www.readbyqxmd.com/read/28558976/chronic-exposure-to-tumor-necrosis-factor-in-vivo-induces-hyperalgesia-upregulates-sodium-channel-gene-expression-and-alters-the-cellular-electrophysiology-of-dorsal-root-ganglion-neurons
#16
Bradford D Fischer, Cojen Ho, Igor Kuzin, Andrea Bottaro, Michael E O'Leary
The goal of these studies was to investigate the links between chronic exposure to the pro-inflammatory cytokine tumor necrosis factor (TNF), hyperalgesia and the excitability of dorsal root ganglion (DRG) sensory neurons. We employed transgenic mice that constitutively express TNF (TNFtg mice), a well-established model of chronic systemic inflammation. At 6 months of age, TNFtg mice demonstrated increased sensitivity to both mechanical and thermal heat stimulation relative to aged-matched wild-type controls...
May 27, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28557626/response-characteristics-and-retinal-origin-of-the-photopic-negative-response-of-the-electroretinogram-in-dogs
#17
Shunsuke Takada, Junzo Kinoshita, Noriaki Iwata, Masako Imaoka, Yoshiro Tani
PURPOSE: To investigate the response characteristics and retinal origin of the photopic negative response (PhNR) of the electroretinograms (ERGs) in dogs. METHODS: Photopic ERGs were elicited by white flash stimuli of different intensities under a steady white background illumination in four anesthetized dogs. These ERGs were also recorded in the same manner after intravitreal injection of tetrodotoxin (TTX). Additionally, retinal localization of voltage-gated sodium channel Nav 1...
May 30, 2017: Current Eye Research
https://www.readbyqxmd.com/read/28555092/tetrodotoxin-for-moderate-to-severe-cancer-related-pain-a-multicentre-randomized-double-blind-placebo-controlled-parallel-design-trial
#18
Neil A Hagen, Lyne Cantin, John Constant, Tina Haller, Gilbert Blaise, May Ong-Lam, Patrick du Souich, Walter Korz, Bernard Lapointe
OBJECTIVE: This study evaluated subcutaneous injections of tetrodotoxin (TTX) for the treatment of moderate to severe, inadequately controlled cancer-related pain. METHODS: Eligible patients were randomized to receive TTX (30 μg) or placebo subcutaneously twice daily for four consecutive days. Efficacy was assessed using pain and composite endpoints (including pain and quality of life measures), and safety was evaluated using standard measures. RESULTS: 165 patients were enrolled at 19 sites in Canada, Australia, and New Zealand, with 149 patients in the primary analysis "intent-to-treat" population...
2017: Pain Research & Management: the Journal of the Canadian Pain Society
https://www.readbyqxmd.com/read/28554984/the-effect-of-deoxycholic-acid-on-secretion-and-motility-in-the-rat-and-guinea-pig-large-intestine
#19
Nam Hee Kim, Jung Ho Park, Jae-Soon Park, Yeun-Ho Joung
Background/Aims: Bile acid is an important luminal factor that affects gastrointestinal motility and secretion. We investigated the effect of bile acid on secretion in the proximal and distal rat colon and coordination of bowel movements in the guinea pig colon. Methods: The short-circuit current from the mucosal strip of the proximal and distal rat colon was compared under control conditions after induction of secretion with deoxycholic acid (DCA) as well as after inhibition of secretion with indomethacin, 1,2-bis (o-aminophenoxy) ethane-N, N,N',N'-tetra-acetic acid (an intracellular calcium chelator; BAPTA), and tetrodotoxin (TTX) using an Ussing chamber...
May 29, 2017: Journal of Neurogastroenterology and Motility
https://www.readbyqxmd.com/read/28551126/rapid-in-vivo-determination-of-tetrodotoxin-in-pufferfish-fugu-muscle-by-solid-phase-microextraction-coupled-to-high-performance-liquid-chromatography-tandem-mass-spectrometry
#20
Le Chen, Junlang Qiu, Yijia Tang, Jianqiao Xu, Shuyao Huang, Yuan Liu, Gangfeng Ouyang
Tetrodotoxin (TTX) is one of the most toxic substances of non-protein in nature. In present study, a rapid and sensitive method based on in vivo solid-phase microextraction (SPME) coupled to liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed to detect the endogenous TTX in pufferfish (Fugu). Fiber evaluation experiments demonstrated that, compared with the commercial PDMS and PA fibers, the home-made electrospun PS@PDA-GA fibers exhibited much better extraction performance towards to TTX in water (120 times and 20 times, respectively), under the optimized conditions...
August 15, 2017: Talanta
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