Investigations into the origin of the high pressure neurological syndrome: the interaction between pressure, strychnine and 1,2-propandiols in the mouse.

PubMed Central

Bowser-Riley, F.; Daniels, S.; Smith, E. B.

1988-01-01

1. The effects of a variety of structural isomers of the centrally acting muscle relaxant mephenesin on the high pressure neurological syndrome have been investigated. Threshold pressures for the onset of the behavioural signs, tremors and convulsions, were established. The effects of these compounds on the response to pressure were also compared with their ability to antagonize the convulsive action of strychnine. 2. The dose-response relationships for strychnine and picrotoxin were investigated at fixed pressures. Additionally, the dose-response relationship of strychnine, in the presence of mephenesin, at pressure was investigated. 3. All the isomers of mephenesin protected against the effects of both pressure and strychnine. The relative potency was found to be identical with respect to both. Mephenesin was clearly the most effective; it raised the threshold pressure for tremors by 2.5 times, that for convulsions elicited by pressure by 1.5 and the ED50 for strychnine convulsions by 1.6 times. Strychnine was found to be strictly additive with pressure whereas picrotoxin exhibited gross deviations from additivity. Mephenesin ameliorated the combined effects of pressure and strychnine equally. 4. The marked dependence on structure of the anticonvulsant activity of the mephenesin isomers can be interpreted as evidence that pressure acts not by some general perturbation of the membranes of excitable cells but rather via some specific interaction. The finding that strychnine and pressure are strictly additive supports the idea of specificity and also indicates that they may share a common mechanism in the production of convulsions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3207974

Strychnine, but not PMBA, inhibits neuronal nicotinic acetylcholine receptors expressed by rabbit retinal ganglion cells.

PubMed

Renna, J M; Strang, C E; Amthor, F R; Keyser, K T

2007-01-01

Strychnine is considered a selective competitive antagonist of glycine gated Cl- channels (Saitoh et al., 1994) and studies have used strychnine at low micromolar concentrations to study the role of glycine in rabbit retina (Linn, 1998; Protti et al., 2005). However, other studies have shown that strychnine, in the concentrations commonly used, is also a potent competitive antagonist of alpha7 nicotinic acetylcholine receptors (nAChRs; Matsubayashi et al., 1998). We tested the effects of low micromolar concentrations of strychnine and 3-[2'-phosphonomethyl[1,1'-biphenyl]-3-yl] alanine (PMBA), a specific glycine receptor blocker (Saitoh et al., 1994; Hosie et al., 1999) on the activation of both alpha7 nAChRs on retinal ganglion cells and on ganglion cell responses to a light flash. Extracellular recordings were obtained from ganglion cells in an isolated retina/choroid preparation and 500 microM choline was used as an alpha7 agonist (Alkondon et al., 1997). We recorded from brisk sustained and brisk transient OFF cells, many of which have been previously shown to have alpha7 receptors (Strang et al., 2005). Further, we tested the effect of strychnine, PMBA and alpha-bungarotoxin on the binding of tetramethylrhodamine alpha-bungarotoxin in the inner plexiform layer. Our data indicates that strychnine, at doses as low as 1.0 microM, can inhibit the alpha7 nAChR-mediated response to choline, but PMBA at concentrations as high as 0.4 microM does not. Binding studies show strychnine and alpha-bungarotoxin inhibit binding of labeled alpha-bungarotoxin in the IPL. Thus, the effects of strychnine application may be to inhibit glycine receptors expressed by ganglion cell or to inhibit amacrine cell alpha7 nAChRs, both of which would result in an increase in the ganglion cell responses. Further research will be required to disentangle the effects of strychnine previously believed to be caused by a single mechanism of glycine receptor inhibition.

Case report: Survival after deliberate strychnine self-poisoning, with toxicokinetic data

PubMed Central

Wood, David Michael; Webster, Emma; Martinez, Daniel; Dargan, Paul Ivor; Jones, Alison Linda

2002-01-01

Introduction Strychnine poisoning is uncommon, and in most severe cases, the patient dies before reaching hospital. The management of strychnine poisoning is well documented, although there are few data on the kinetics of elimination of strychnine after overdose. Case report A 42-year-old man presented shortly after ingestion of an unknown quantity of strychnine powder. After a respiratory arrest, with intensive supportive management requiring admission to an intensive care unit, he survived. Eight serum samples were taken over the first 5 days and analysed subsequently for strychnine concentrations. Results The initial concentration at 1.5 hours after ingestion was 4.73 mg/l, falling to 0.38 mg/l at 74 hours postingestion. Serum concentrations followed a monoexponential elimination curve with a calculated elimination half-life of 12 hours. Discussion and conclusion Strychnine poisoning presents with classical features, and with early diagnosis and supportive management, the patient can survive. The initial serum concentration of 4.73 mg/l is the highest reported concentration in a patient who has survived. Previous reports of the elimination half-life have suggested it is between 10 and 16 hours, which conforms to the elimination data in our case. PMID:12398788

Is there no end to the total syntheses of strychnine? Lessons to be learned for strategy and tactics in total synthesis**

PubMed Central

Cannon, Jeffrey S.; Overman, Larry E.

2013-01-01

From the 19th century to the present, the complex indole alkaloid strychnine has engaged the chemical community. In this review, we examine why strychnine has been and remains today an important target for directed synthesis efforts. A selection of the diverse syntheses of strychnine is discussed with the aim of identifying their influence on the evolution of the strategy and tactics of organic synthesis. PMID:22431197

Strychnine and Taurine Modulation of Amygdala-associated Anxiety-like Behavior is ‘State’ Dependent

PubMed Central

McCool, Brian A.; Chappell, Ann

2007-01-01

Strychnine-sensitive glycine receptors are expressed in many adult forebrain regions, yet the biological function of these receptors outside the spinal cord/brainstem is poorly understood. We have recently shown that rat lateral/basolateral amygdala neurons express strychnine-sensitive glycine-gated currents whose pharmacological and molecular characteristics are consistent with those established for classic ligand-gated chloride channels. The current studies were undertaken to establish the behavioral role, if any, of these strychnine-sensitive glycine receptors. Adult Long-Evans male rats were implanted with guide cannulae targeted at the lateral amygdala and were micro-injected with standard artificial cerebrospinal fluid with or without various doses of strychnine or taurine. Anxiety-like behaviors were assessed with the elevated plus-maze or the light/dark box. In the elevated plus maze, strychnine decreased closed-arm time and increased open-arm time, suggestive of an anxiolytic effect. Similarly, strychnine produced a modest anxiolytic effect in the light/dark box. Post-hoc analysis of ‘open-arm’ time and ‘light-side’ time indicated that aCSF-treated animals were distributed into two apparent groups that displayed either high or low amounts of anxiety-like behavior in a given apparatus. Surprisingly, the pharmacological effects of both strychnine and taurine in these assays were dependent upon a given animal’s behavioral phenotype. Together, these findings are significant because they suggest that the basal ‘emotional state’ of the animal could influence the behavioral outcome associated with drug application directly into the lateral/basolateral amygdala. Furthermore, our findings also suggest that compounds acting at amygdala strychnine-sensitive glycine receptors may actively modulate this basal anxiety-like state. PMID:17207866

An unusual case of strychnine poisoning.

PubMed

Prat, Sebastien; Hoizey, Guillaume; Lefrancq, Thierry; Saint-Martin, Pauline

2015-05-01

Strychnine-related death has been described since the 19th century. This alkaloid was discovered in 1818. Historically, strychnine was used by the South-East Asian autochthones on their arrows. However, its production was modified by legislation, which was used to protect people against accidental intoxications. Here, we present the case of a 69-year-old man who was found dead at home. During the autopsy, we found a blue substance in the stomach. Toxicological analysis measured strychnine at 0.29 μg/mL in the blood sample, which is a relatively low level in comparison with the results given in the literature. However, histologic examination and toxicological findings permitted the conclusion of strychnine poisoning. © 2015 American Academy of Forensic Sciences.

Oxime Ethers of (E)-11-Isonitrosostrychnine as Highly Potent Glycine Receptor Antagonists.

PubMed

Mohsen, Amal M Y; Mandour, Yasmine M; Sarukhanyan, Edita; Breitinger, Ulrike; Villmann, Carmen; Banoub, Maha M; Breitinger, Hans-Georg; Dandekar, Thomas; Holzgrabe, Ulrike; Sotriffer, Christoph; Jensen, Anders A; Zlotos, Darius P

2016-12-23

A series of (E)-11-isonitrosostrychnine oxime ethers, 2-aminostrychnine, (strychnine-2-yl)propionamide, 18-oxostrychnine, and N-propylstrychnine bromide were synthesized and evaluated pharmacologically at human α1 and α1β glycine receptors in a functional fluorescence-based and a whole-cell patch-clamp assay and in [ 3 H]strychnine binding studies. 2-Aminostrychnine and the methyl, allyl, and propargyl oxime ethers were the most potent α1 and α1β antagonists in the series, displaying IC 50 values similar to those of strychnine at the two receptors. Docking experiments to the strychnine binding site of the crystal structure of the α3 glycine receptor indicated the same orientation of the strychnine core for all analogues. For the most potent oxime ethers, the ether substituent was accommodated in a lipophilic receptor binding pocket. The findings identify the oxime hydroxy group as a suitable attachment point for linking two strychnine pharmacophores by a polymethylene spacer and are, therefore, important for the design of bivalent ligands targeting glycine receptors.

Strychnine-blocked glycine receptor is removed from synapses by a shift in insertion/degradation equilibrium.

PubMed

Rasmussen, Hanne; Rasmussen, Trine; Triller, Antoine; Vannier, Christian

2002-02-01

The long-term inhibition by strychnine of glycine receptor activity in neurons provokes the receptor's selective intracellular accumulation and disappearance from synapses. This could result either from a disruption of the postsynaptic anchoring of the receptor or from an arrest of its exocytic transport. In this study we combined biochemical and fluorescence microscopy analyses to determine on a short time scale the fate of the strychnine-inactivated glycine receptor. Quantification of the cellular content of receptor showed that the rapid accumulation depends on protein synthesis. Cell surface biotinylation of neurons demonstrated that strychnine did not accelerate the turnover rate of the receptor. Labeling of endosomes indicated that, in strychnine-treated cells, the accumulated receptor is not blocked in the endosomal transport pathway. Taken together, these results indicate that strychnine does not destabilize the postsynaptic receptor but triggers its disappearance from synapses by a nondegradative sequestration of newly synthesized molecules in a nonendocytic compartment. (C)2002 Elsevier Science (USA).

A Drosophila Gustatory Receptor Required for Strychnine Sensation

PubMed Central

Lee, Youngseok; Moon, Seok Jun; Wang, Yijin

2015-01-01

Strychnine is a potent, naturally occurring neurotoxin that effectively protects plants from animal pests by deterring feeding behavior. In insects, such as the fruit fly, Drosophila melanogaster, bitter-tasting aversive compounds are detected primarily through a family of gustatory receptors (GRs), which are expressed in gustatory receptor neurons. We previously described multiple GRs that eliminate the behavioral avoidance to all bitter compounds tested, with the exception of strychnine. Here, we report the identity of a strychnine receptor, referred to as GR47a. We generated a mutation in Gr47a and found that it eliminated strychnine repulsion and strychnine-induced action potentials. GR47a was narrowly tuned, as the responses to other avoidance compounds were unaffected in the mutant animals. This analysis supports an emerging model that Drosophila GRs fall broadly into two specificity classes—one class is comprised of core receptors that are broadly required, whereas the other class, which includes GR47a, consists of narrowly tuned receptors that define chemical specificity. PMID:26187906

Total Synthesis of Strychnine.

PubMed

Lee, Geun Seok; Namkoong, Gil; Park, Jisook; Chen, David Y-K

2017-11-16

The total synthesis of the flagship Strychnos indole alkaloid, strychnine, has been accomplished. The developed synthetic sequence features a novel vinylogous 1,4-addition, a challenging iodinium salt mediated silyl enol ether arylation, a palladium-catalyzed Heck reaction, and a streamlined late-stage conversion to strychnine. Furthermore, an application of asymmetric counterion-directed catalysis (ACDC) in the context of target-oriented organic synthesis has been rendered access to an optically active material. The synthetic sequence described herein represents the most concise entry to optically active strychnine to date. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Is there no end to the total syntheses of strychnine? Lessons learned in strategy and tactics in total synthesis.

PubMed

Cannon, Jeffrey S; Overman, Larry E

2012-04-27

From the 19th century to the present, the complex indole alkaloid strychnine has engaged the chemical community. In this Review, we examine why strychnine has been and remains today an important target for directed synthesis efforts. A selection of the diverse syntheses of strychnine is discussed with the aim of identifying their influence on the evolution of the strategy and tactics of organic synthesis. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Specific strychnine binding sites on acrosome-associated membranes of golden hamster spermatozoa.

PubMed

Llanos, Miguel N; Ronco, Ana M; Aguirre, María C

2003-06-27

This study demonstrates for the first time, that membrane vesicles originated from the hamster sperm head after the occurrence of the acrosome reaction, possess specific strychnine binding sites. [3H]Strychnine binding was saturable and reversible, being displaced by unlabeled strychnine (IC(50)=26.7+/-2.3 microM). Kinetic analysis revealed one binding site with K(d)=120nM and B(max)=142fmol/10(6) spermatozoa. Glycine receptor agonists beta-alanine and taurine inhibited strychnine binding by 20-30%. Surprisingly, glycine stimulated binding by about 40-50%. Results obtained in this study strongly suggest the presence of glycine receptors-with distinctive kinetic properties on the periacrosomal plasma membrane of hamster spermatozoa. Localization of this receptor fits well with its previously proposed role in acrosomal exocytosis during mammalian fertilization.

Strychnine inhibits inflammatory angiogenesis in mice via down regulation of VEGF, TNF-α and TGF-β.

PubMed

Saraswati, Sarita; Agarwal, S S

2013-05-01

Strychnine is known to possess anti-inflammatory and antitumour activity, but its roles in tumour angiogenesis, the key step involved in tumour growth and metastasis, and the involved molecular mechanism are still unknown. We aimed to investigate the effects of strychnine on key components of inflammatory angiogenesis in the murine cannulated sponge implant angiogenesis model. Polyester-polyurethane sponges, used as a framework for fibrovascular tissue growth, were implanted in Swiss albino mice and strychnine (0.25, and 0.5 mg/kg/day) was given through installed cannulas for 9 days. The implants collected at day 9 postimplantation were processed for the assessment of haemoglobin (Hb), myeloperoxidase (MPO), N-acetylglucosaminidase (NAG) and collagen used as indexes for angiogenesis, neutrophil and macrophage accumulation and extracellular matrix deposition, respectively. Relevant inflammatory, angiogenic and fibrogenic cytokines were also determined. Strychnine treatment attenuated the main components of the fibrovascular tissue, wet weight, vascularization (Hb content), macrophage recruitment (NAG activity), collagen deposition and the levels of vascular endothelial growth factor (VEGF), tumour necrosis factor (TNF)-α and transforming growth factor (TGF-β). A regulatory function of strychnine on multiple parameters of main components of inflammatory angiogenesis has been revealed giving insight into the potential therapeutic underlying the actions of strychnine. Copyright © 2013 Elsevier Inc. All rights reserved.

The membrane effects, and sensitivity to strychnine, of neural inhibition of the Mauthner cell, and its inhibition by glycine and GABA

PubMed Central

Diamond, J.; Roper, S.; Yasargil, G. M.

1973-01-01

1. Anionic conductance changes in Mauthner neurones of goldfish were measured during synaptically evoked inhibition and inhibition caused by iontophoretic application of the putative inhibitory transmitters glycine and γ-aminobutyric acid (GABA). 2. The effects of either amino acid were indistinguishable from those of the neural inhibitory transmitter(s). The membrane permeability during the neural or drug response was increased to Br-, Cl-, I-, SCN-, NO3-, ClO3-, and formate (HCOO-), but not to HCO3-, BrO3-, IO3-, SO4-, HPO4-, H2PO4-, acetate and citrate. 3. Strychnine was injected intramuscularly, iontophoretically, or applied topically to the exposed brain in order to compare quantitatively its ability to prevent inhibition evoked by synaptic activation and by pharmacological means. Inhibitions were measured by the increase in membrane conductance. 4. Strychnine, at concentrations just adequate to block completely the late collateral inhibition (LCI) and crossed VIII nerve inhibition, had little effect on the pharmacological inhibition caused by glycine, and sometimes there was no detectable effect at all. In one experiment even a local iontophoretic application of strychnine in a sufficient dose to diffuse over the cell and block the LCI almost completely, merely halved the effect of a small dose of glycine applied to the same localized region of the membrane. 5. Higher concentrations of strychnine than those necessary to block synaptically evoked inhibition would reduce the effect of glycine but not that of GABA. The evidence indicated that any apparent effect of strychnine upon GABA could be explained by displacement of the GABA-containing iontophoretic pipette. 6. The glycine-blocking action of iontophoretic pulses of strychnine was of relatively very slow onset and long duration compared to the effects of pulses of glycine and GABA. 7. These findings can be interpreted as either (1) strychnine has a presynaptic action, preventing the release of inhibitory neurotransmitter, in addition to its less potent post-synaptic one in blocking pharmacological inhibition, or (2) strychnine acts entirely post-synaptically, but the physiological transmitter action differs from that of glycine and GABA in being considerably more sensitive to strychnine antagonism. In either case, the use of strychnine as evidence for the claim that glycine is an inhibitory neurotransmitter at the Mauthner cell is questionable. PMID:4354770

A Drosophila Gustatory Receptor Required for Strychnine Sensation.

PubMed

Lee, Youngseok; Moon, Seok Jun; Wang, Yijin; Montell, Craig

2015-09-01

Strychnine is a potent, naturally occurring neurotoxin that effectively protects plants from animal pests by deterring feeding behavior. In insects, such as the fruit fly, Drosophila melanogaster, bitter-tasting aversive compounds are detected primarily through a family of gustatory receptors (GRs), which are expressed in gustatory receptor neurons. We previously described multiple GRs that eliminate the behavioral avoidance to all bitter compounds tested, with the exception of strychnine. Here, we report the identity of a strychnine receptor, referred to as GR47a. We generated a mutation in Gr47a and found that it eliminated strychnine repulsion and strychnine-induced action potentials. GR47a was narrowly tuned, as the responses to other avoidance compounds were unaffected in the mutant animals. This analysis supports an emerging model that Drosophila GRs fall broadly into two specificity classes-one class is comprised of core receptors that are broadly required, whereas the other class, which includes GR47a, consists of narrowly tuned receptors that define chemical specificity. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

HPLC determination of strychnine and brucine in rat tissues and the distribution study of processed semen strychni.

PubMed

Chen, Jun; Hou, Ting; Fang, Yun; Chen, Zhi-peng; Liu, Xiao; Cai, Hao; Lu, Tu-lin; Yan, Guo-jun; Cai, Bao-chang

2011-01-01

A simple and low-cost HPLC method with UV absorbance detection was developed and validated to simultaneously determine strychnine and brucine, the most abundant alkaloids in the processed Semen Strychni, in rat tissues (kidney, liver, spleen, lung, heart, stomach, small intestine, brain and plasma). The tissue samples were treated with a simple liquid-liquid extraction prior to HPLC. The LOQs were in the range of 0.039-0.050 µg/ml for different tissue or plasma samples. The extraction recoveries varied from 71.63 to 98.79%. The linear range was 0.05-2 µg/ml with correlation coefficient of over 0.991. The intra- and inter-day precision was less than 15%. Then the method was used to measure the tissue distribution of strychnine and brucine after intravenous administration of 1 mg/kg crude alkaloids fraction (CAF) extracted from the processed Semen Strychni. The results revealed that strychnine and brucine possessed similar tissue distribution characterization. The highest level was observed in kidney, while the lowest level was found in brain. It was indicated that kidney might be the primary excretion organ of prototype strychnine and brucine. It was also deduced that strychnine and brucine had difficulty in crossing the blood-brain barrier. Furthermore, no long-term accumulation of strychnine and brucine was found in rat tissues.

Strychnine activates neuronal α7 nicotinic receptors after mutations in the leucine ring and transmitter binding site domains

PubMed Central

Palma, Eleonora; Fucile, Sergio; Barabino, Benedetta; Miledi, Ricardo; Eusebi, Fabrizio

1999-01-01

Recent work has shown that strychnine, the potent and selective antagonist of glycine receptors, is also an antagonist of nicotinic acetylcholine (AcCho) receptors including neuronal homomeric α7 receptors, and that mutating Leu-247 of the α7 nicotinic AcCho receptor-channel domain (L247Tα7; mut1) converts some nicotinic antagonists into agonists. Therefore, a study was made of the effects of strychnine on Xenopus oocytes expressing the chick wild-type α7 or L247Tα7 receptors. In these oocytes, strychnine itself did not elicit appreciable membrane currents but reduced the currents elicited by AcCho in a reversible and dose-dependent manner. In sharp contrast, in oocytes expressing L247Tα7 receptors with additional mutations at Cys-189 and Cys-190, in the extracellular N-terminal domain (L247T/C189–190Sα7; mut2), micromolar concentrations of strychnine elicited inward currents that were reversibly inhibited by the nicotinic receptor blocker α-bungarotoxin. Single-channel recordings showed that strychnine gated mut2-channels with two conductance levels, 56 pS and 42 pS, and with kinetic properties similar to AcCho-activated channels. We conclude that strychnine is a modulator, as well as an activator, of some homomeric nicotinic α7 receptors. After injecting oocytes with mixtures of cDNAs encoding mut1 and mut2 subunits, the expressed hybrid receptors were activated by strychnine, similar to the mut2, and had a high affinity to AcCho like the mut1. A pentameric symmetrical model yields the striking conclusion that two identical α7 subunits may be sufficient to determine the functional properties of α7 receptors. PMID:10557336

A novel antagonist, phenylbenzene omega-phosphono-alpha-amino acid, for strychnine-sensitive glycine receptors in the rat spinal cord.

PubMed Central

Saitoh, T; Ishida, M; Maruyama, M; Shinozaki, H

1994-01-01

1. 3-[2'-Phosphonomethyl[1,1'-biphenyl]-3-yl]alanine (PMBA) is a novel glycine antagonist at strychnine-sensitive receptors. The chemical structure of PMBA, possessing both a glycine moiety and a phosphono group, is quite different from that of strychnine. 2. In the spinal motoneurone of newborn rats, glycine (100 microM-1 mM) induced depolarizing responses in a concentration-dependent manner. PMBA effectively inhibited depolarizing responses to glycine and other agonists, such as taurine and beta-alanine. The dose-response curves for glycine were shifted to the right in an almost parallel manner (pA2 value: 5.30 +/- 0.23, n = 5) by PMBA which was about 60 times less potent than strychnine (pA2 value: 7.08 +/- 0.21, n = 5) as a glycine antagonist. 3. PMBA (1-100 microM) did not interact with modulatory glycine sites on N-methyl-D-aspartate (NMDA) receptors, which suggests a high selectivity of PMBA for strychnine-sensitive glycine receptors. At considerably high concentrations (0.1 mM-1 mM), PMBA depressed responses to GABA (pA2 value: 3.57 +/- 0.24, n = 3). 4. PMBA inhibited the binding of [3H]-strychnine to synaptosomes from adult rat spinal cords; the IC50 values of PMBA, glycine and strychnine were 8 +/- 2, 9 +/- 3 and 0.08 +/- 0.04 microM, respectively (n = 5) for [3H]-strychnine (4.8 nM). 5. PMBA is a central excitant drug with relatively high potency and selectivity and should be useful as a pharmacological probe for analysing the mechanisms underlying physiological functions of glycine receptors. PMID:7812607

A Structural and Mutagenic Blueprint for Molecular Recognition of Strychnine and d-Tubocurarine by Different Cys-Loop Receptors

PubMed Central

Kuzmin, Dmitry; van Elk, René; Krijnen, Liz; Yakel, Jerrel L.; Tsetlin, Victor; Smit, August B.; Ulens, Chris

2011-01-01

Cys-loop receptors (CLR) are pentameric ligand-gated ion channels that mediate fast excitatory or inhibitory transmission in the nervous system. Strychnine and d-tubocurarine (d-TC) are neurotoxins that have been highly instrumental in decades of research on glycine receptors (GlyR) and nicotinic acetylcholine receptors (nAChR), respectively. In this study we addressed the question how the molecular recognition of strychnine and d-TC occurs with high affinity and yet low specificity towards diverse CLR family members. X-ray crystal structures of the complexes with AChBP, a well-described structural homolog of the extracellular domain of the nAChRs, revealed that strychnine and d-TC adopt multiple occupancies and different ligand orientations, stabilizing the homopentameric protein in an asymmetric state. This introduces a new level of structural diversity in CLRs. Unlike protein and peptide neurotoxins, strychnine and d-TC form a limited number of contacts in the binding pocket of AChBP, offering an explanation for their low selectivity. Based on the ligand interactions observed in strychnine- and d-TC-AChBP complexes we performed alanine-scanning mutagenesis in the binding pocket of the human α1 GlyR and α7 nAChR and showed the functional relevance of these residues in conferring high potency of strychnine and d-TC, respectively. Our results demonstrate that a limited number of ligand interactions in the binding pocket together with an energetic stabilization of the extracellular domain are key to the poor selective recognition of strychnine and d-TC by CLRs as diverse as the GlyR, nAChR, and 5-HT3R. PMID:21468359

A structural and mutagenic blueprint for molecular recognition of strychnine and d-tubocurarine by different cys-loop receptors.

PubMed

Brams, Marijke; Pandya, Anshul; Kuzmin, Dmitry; van Elk, René; Krijnen, Liz; Yakel, Jerrel L; Tsetlin, Victor; Smit, August B; Ulens, Chris

2011-03-01

Cys-loop receptors (CLR) are pentameric ligand-gated ion channels that mediate fast excitatory or inhibitory transmission in the nervous system. Strychnine and d-tubocurarine (d-TC) are neurotoxins that have been highly instrumental in decades of research on glycine receptors (GlyR) and nicotinic acetylcholine receptors (nAChR), respectively. In this study we addressed the question how the molecular recognition of strychnine and d-TC occurs with high affinity and yet low specificity towards diverse CLR family members. X-ray crystal structures of the complexes with AChBP, a well-described structural homolog of the extracellular domain of the nAChRs, revealed that strychnine and d-TC adopt multiple occupancies and different ligand orientations, stabilizing the homopentameric protein in an asymmetric state. This introduces a new level of structural diversity in CLRs. Unlike protein and peptide neurotoxins, strychnine and d-TC form a limited number of contacts in the binding pocket of AChBP, offering an explanation for their low selectivity. Based on the ligand interactions observed in strychnine- and d-TC-AChBP complexes we performed alanine-scanning mutagenesis in the binding pocket of the human α1 GlyR and α7 nAChR and showed the functional relevance of these residues in conferring high potency of strychnine and d-TC, respectively. Our results demonstrate that a limited number of ligand interactions in the binding pocket together with an energetic stabilization of the extracellular domain are key to the poor selective recognition of strychnine and d-TC by CLRs as diverse as the GlyR, nAChR, and 5-HT(3)R.

Effects of strychnine on the sodium conductance of the frog node of Ranvier

PubMed Central

1977-01-01

Strychnine blocks sodium conductance in the frog node of Ranvier. This block was studied by reducing and slowing sodium inactivation with scorpion venom. The block is voltage and time dependent. The more positive the axoplasm the greater the block and the faster the approach to equilibrium. Some evidence is presented suggesting that only open channels can be blocked. The block is reduced by raising external sodium or lithium but not impermeant cations. A quaternary derivative of strychnine was synthesized and found to have the same action only when applied intracellularly. We conclude that strychnine blocks sodium channels by a mechanism analogous to that by which it blocks potassium channels. The potassium channel block had previously been found to be identical to that by tetraethylammonium ion derivatives. In addition, strychnine resembles procaine and its derivatives in both its structure and the mechanism of sodium channel block. PMID:302321

Concise Syntheses of bis-Strychnos Alkaloids (-)-Sungucine, (-)-Isosungucine, and (-)-Strychnogucine B from (-)-Strychnine.

PubMed

Zhao, Senzhi; Teijaro, Christiana N; Chen, Heng; Sirasani, Gopal; Vaddypally, Shivaiah; Zdilla, Michael J; Dobereiner, Graham E; Andrade, Rodrigo B

2016-08-08

The first chemical syntheses of complex, bis-Strychnos alkaloids (-)-sungucine (1), (-)-isosungucine (2), and (-)-strychnogucine B (3) from (-)-strychnine (4) is reported. Key steps included (1) the Polonovski-Potier activation of strychnine N-oxide; (2) a biomimetic Mannich coupling to forge the signature C23-C5' bond that joins two monoterpene indole monomers; and (3) a sequential HBr/NaBH3 CN-mediated reduction to fashion the ethylidene moieties in 1-3. DFT calculations were employed to rationalize the regiochemical course of reactions involving strychnine congeners. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bisquaternary dimers of strychnine and brucine. A new class of potent enhancers of antagonist binding to muscarinic M2 receptors.

PubMed

Zlotos, D P; Buller, S; Holzgrabe, U; Mohr, K

2003-06-12

Bisquaternary dimers of strychnine and brucine were synthesized and their allosteric effect on muscarinic acetylcholine M(2) receptors was examined. The compounds retarded the dissociation of the antagonist [(3)H]N-methylscopolamine ([(3)H]NMS) from porcine cardiac cholinoceptors. This action indicated ternary complex formation. All compounds exhibited higher affinity to the allosteric site of [(3)H]NMS-occupied M(2) receptors than the monomeric strychnine and brucine, while the positive cooperativity with NMS was fully maintained. SAR studies revealed the unchanged strychnine ring as an important structural feature for high allosteric potency.

[Strychnine poisoning].

PubMed

Scheffold, N; Heinz, B; Albrecht, H; Pickert, A; Cyran, J

2004-10-15

A 46-year-old man presented two hours after ingestion of about 250 mg strychnine with severe violent, generalized convulsions, triggered by external stimuli. During the convulsion-free periods there were no abnormal signs in the physical examination. The presence of strychnine was confirmed by urine analysis with gas chromatography-mass spectrometry. Because diazepam as anticonvulsant of choice was not effective in abating the convulsions the patient was intubated. A combination with midazolam, fentanyl and pancuronium was effective in controlling the convulsions. The patient was discharged from ICU on day three. Fatal outcome of strychnine poisoning demands an aggressive management with early intubation, control of muscle tremors and prevention of rhabdomyolisis and renal failure.

Pharmacological characterisation of strychnine and brucine analogues at glycine and alpha7 nicotinic acetylcholine receptors.

PubMed

Jensen, Anders A; Gharagozloo, Parviz; Birdsall, Nigel J M; Zlotos, Darius P

2006-06-06

Strychnine and brucine from the plant Strychnos nux vomica have been shown to have interesting pharmacological effects on several neurotransmitter receptors, including some members of the superfamily of ligand-gated ion channels. In this study, we have characterised the pharmacological properties of tertiary and quaternary analogues as well as bisquaternary dimers of strychnine and brucine at human alpha1 and alpha1beta glycine receptors and at a chimera consisting of the amino-terminal domain of the alpha7 nicotinic receptor (containing the orthosteric ligand binding site) and the ion channel domain of the 5-HT3A serotonin receptor. Although the majority of the analogues displayed significantly increased Ki values at the glycine receptors compared to strychnine and brucine, a few retained the high antagonist potencies of the parent compounds. However, mirroring the pharmacological profiles of strychnine and brucine, none of the analogues displayed significant selectivity between the alpha1 and alpha1beta subtypes. The structure-activity relationships for the compounds at the alpha7/5-HT3 chimera were significantly different from those at the glycine receptors. Most strikingly, quaternization of strychnine and brucine with substituents possessing different steric and electronic properties completely eliminated the activity at the glycine receptors, whereas binding affinity to the alpha7/5-HT3 chimera was retained for the majority of the quaternary analogues. This study provides an insight into the structure-activity relationships for strychnine and brucine analogues at these ligand-gated ion channels.

Cytotoxicity and DNA interaction of brucine and strychnine-Two alkaloids of semen strychni.

PubMed

Liu, Fei; Wang, Xiaolin; Han, Xu; Tan, Xiaoxin; Kang, Weijun

2015-01-01

The cytotoxicities of the two alkaloids strychnine and brucine from the seed of Strychnos nux-vomica and their interaction with DNA were investigated. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrasolium bromide (MTT) assay was used to examine the growth inhibitory effects of these alkaloids on Vero cells after 24, 48 and 72h of incubation. The cytotoxicities of strychnine and brucine were found to be time- and concentration-dependent. Strychnine was determined to be more toxic to Vero cells than brucine. At the same time, the interactions of strychnine and brucine with DNA were investigated using neutral red (NR) dye as a probe by UV-vis spectroscopy, fluorescence spectroscopy, and an examination of the ionic strength effect, and the effects of alkaloids on DNA melting were also examined. The results indicated that a DNA-brucine mixture but not a DNA-strychnine mixture could be extracted from Vero cells after treatment with brucine and strychnine, respectively. Brucine competitively intercalated into the DNA double-helix causing fluorescence quenching of the DNA-NR system. UV absorption spectroscopy and the melting temperature (Tm) curve also provided evidence that brucine interacted with DNA through intercalation. Furthermore, the results of the ionic strength effect experiment suggested that electrostatic interactions between brucine and phosphate groups in the DNA backbone might also play an important role in the binding of brucine to DNA. Copyright © 2015 Elsevier B.V. All rights reserved.

Pharmacological evaluation of total alkaloids from nux vomica: effect of reducing strychnine contents.

PubMed

Chen, Jun; Qu, Yange; Wang, Dongyue; Peng, Pei; Cai, Hao; Gao, Ying; Chen, Zhipeng; Cai, Baochang

2014-04-10

The aim of the study was to investigate the possibility of improving the therapeutic efficacy of the total alkaloid fraction (TAF) extracted from processed nux vomica by reducing the strychnine contents. Most strychnine was removed from TAF to obtain the modified total alkaloid fraction (MTAF). The toxicity and pharmacokinetics of TAF and MTAF were further investigated and compared besides their antitumor, analgesic and anti-inflammatory activities. The results showed that the ratios of brucine to strychnine were 1:2.05 and 2.2:1 for TAF and MTAF, respectively, and the toxicity of TAF was about 3.17-fold higher than that of MTAF. Compared to brucine alone, the elimination of brucine was found to be inhibited by other alkaloids in TAF or MTAF except strychnine. Significantly increased pharmacological activities when administered by the oral route were obtained with MTAF in comparison to TAF and nux vomica powder (NVP). In summary, MTAF might replace NVP and TAF in the clinical application of Chinese medicine to obtain much higher efficacy.

[LC-MS/MS analysis of determination of strychnine and brucine in formaldehyde fixed tissue].

PubMed

Zhan, Lan-fen; Liu, Ming-dong; Yan, You-yi; Ye, Yi; Wang, Wei; Wang, Zhi-hui; Zhao, Jun-hong; Liao, Lin-chuan

2012-10-01

To establish a method for determination of strychnine and brucine in formaldehyde fixed tissue by LC-MS/MS analysis. The samples were pretreated with solid phase extraction using SCX cartridges and separated on SB-C18 column with mobile phase 0.1% formic acid : 0.1% formic acid-acetonitrile (75:25). Electrospray ionization (ESI) source was utilized and operated in positive ion mode. Multiple reactions monitoring (MRM) mode was applied. External standard method was applied for quantitation. The chromatographic separation of strychnine and brucine in formaldehyde fixed nephritic and hepatic tissues resulted successfully. The standard curve was linear in the range of 0.002-2.0 microg/g for strychnine and brucine in formaldehyde fixed tissues, and the correlation coefficient was more than 0.996. The limits of detection (LOD) of strychnine and brucine in nephritic tissues were 0.06ng/g and 0.03 ng/g, respectively. The LOD of both chemicals were 0.3 ng/g in hepatic tissues. The extraction recovery rate was more than 74.5%. The precision of intra-day and inter-day were both less than 8.2%. Strychnine and brucine can be sensitive to be determined in formaldehyde fixed tissue by LC-MS/MS analysis. It can be applied in the forensic toxicological analysis.

The effect of strychnine, bicuculline, and picrotoxin on X and Y cells in the cat retina

PubMed Central

1979-01-01

The effect of intravenous strychnine and the GABA antagonists picrotoxin and bicuculline upon the discharge pattern of center- surround-organized cat retinal ganglion cells of X and Y type were studied. Stimuli (mostly scotopic, and some photopic) were selected such that responses from both on and off-center cells were either due to the center, due to the surround, or clearly mixed. Pre-drug control responses were obtained, and their behavior following administration of the antagonists was observed for periods up to several hours. X-cell responses were affected in a consistent manner by strychnine while being unaffected by GABA antagonists. All observed changes following strychnine were consistent with a shift in center-surround balance of X cells in favor of the center. For Y-cell responses to flashing annuli following strychnine, there was either no shift or a relatively small shift in center-surround balance. Compared to X-cell responses to flashing lights, those of Y cells were very little affected by strychnine and in most cases were unaffected. It thus appears that glycine plays a similar role in receptive field organization of X cells as does GABA in Y cells (Kirby and Enroth-Cugell, 1976. J. Gen. Physiol. 68:465-484). PMID:479822

Behavior and Cellular Evidence for Propofol-Induced Hypnosis Involving Brain Glycine Receptors

PubMed Central

Nguyen, Hai T; Li, Ke-yong; da Graca, Ralph L; Delphin, Ellise; Xiong, Ming; Ye, Jiang H

2009-01-01

Background It is well documented that several general anesthetics, including propofol, potentiate glycine receptor function. Furthermore, glycine receptors exist throughout the central nervous system, including areas of the brain thought to be involved in sleep. However, the role of glycine receptors in anesthetic-induced hypnosis has not been determined. Methods Experiments were conducted in rats, where the loss of righting reflex (LORR) was used as a marker of the hypnotic state. Propofol-induced LORR was examined in the presence and the absence of strychnine (a glycine receptor antagonist), GABAzine (a γ-aminobutyric acid A receptor antagonist), as well as ketamine (an antagonist of N-methyl-D-aspartic acid subtype of glutamate receptors). Furthermore, the effects of propofol on the currents elicited by glycine and γ-aminobutyric acid were analyzed in neurons isolated from the posterior hypothalamus of rats. The effects of strychnine and GABAzine on propofol-induced currents were also evaluated. Results Strychnine and GABAzine dose-dependently reduced the percentage of rats exhibiting LORR induced by propofol. Furthermore, strychnine significantly increased the onset time and reduced the duration of LORR induced by propofol. In contrast, strychnine did not affect the LORR induced by ketamine. Additionally, propofol markedly increased the currents elicited by glycine and GABA of hypothalamic neurons. Conversely, strychnine and GABAzine both profoundly attenuated the current induced by propofol. Conclusion Strychnine, the glycine receptor antagonist dose-dependently reduced propofol-induced loss of righting reflex in rats and propofol-induced current of rat hypothalamic neurons. These results suggest that neuronal glycine receptors partially contribute to propofol-induced hypnosis. PMID:19194159

Microdialysis combined with RRLC-MS/MS for the pharmacokinetics of two major alkaloids of Bi qi capsule and the potential roles of P-gp and BCRP on their penetration.

PubMed

Ren, Tiankun; Li, Menglin; Zheng, Hao; Liu, Wenwei; Zhang, Jinlan

2018-05-31

Bi qi capsule (BQC) is a traditional Chinese medicine prescription that is clinically used for the treatment of rheumatoid arthritis. Strychnine and brucine, as two typical kinds of alkaloids, are the primary active and neurotoxic constituents of BQC. In this study, a sensitive and reliable rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) quantitative method was used to determine the concentrations of brucine and strychnine in rat brain and blood dialysates. The blood-brain barrier (BBB) penetration of free brucine and strychnine and their pharmacokinetic characteristics were investigated by the validated RRLC-MS/MS method coupled with in vivo microdialysis for the first time. The dialysate brain-blood AUC ratios of brucine were 0.098, 0.44 and 0.40 respectively at 0.4, 0.8 and 1.6 g kg -1 doses of BQC, and the dialysate brain-blood AUC ratios of strychnine were 0.20, 1.25 and 2.06 respectively at 0.4, 0.8 and 1.6 g kg -1 doses of BQC. The high brain-blood AUC ratios of brucine and strychnine were observed in medium and high dose groups of BQC. In addition, the effects of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) on brucine and strychnine across BBB were also studied using the above method as well as molecular docking. The results prompted that brucine was the substrate of P-gp, and strychnine might be the inhibitor of P-gp. Brucine and strychnine showed high brain penetration, so it is very important to well control the clinic dosage of BQC and manufactory quality for avoiding the side effects and obtaining good therapeutic efficacy. Our study could be further used in investigating BBB penetration for other drugs caused neurotoxicity. Copyright © 2018 Elsevier B.V. All rights reserved.

[Interaction between strychnine and bovine serum albumin].

PubMed

Zhao, Jin; Wang, Zhi; Wu, Qiu-hua; Yang, Xiu-min; Wang, Chun; Hu, Yan-xue

2006-07-01

To study the interaction between strychnine and bovine serum albumin. Fluorescence spectroscopy and ultraviolet spectroscopy were used. The static quenching and the non-radiation energy transfer are the two main reasons to leading the fluorescence quenching of BSA. The apparent combining constants (K(A)) between strychnine and BSA are 3.72 x 10(3) at 27 degrees C, 4.27 x 10(3) at 37 degrees C, 4.47 x 10(3) at 47 degrees C and the combining sites are 1.01 +/- 0.03. The combining distance (r = 3.795 nm) and energy transfer efficiency (E = 0.0338) are obtained by Förster's non-radiation energy transfer mechanism. The interaction between strychnine and BSA was driven mainly by hydrophobic force.

Strychnine overdose following ingestion of gopher bait.

PubMed

Lindsey, Tania; O'Hara, Joseph; Irvine, Rebecca; Kerrigan, Sarah

2004-03-01

A 52-year-old male was discovered supine on his bed in a state of early decomposition. Commercial strychnine-treated gopher pellets were found in the home, and suicide notes were present at the scene. Biological fluids and tissues were tested for basic, acidic, and neutral drugs using gas chromatography-mass spectrometry. Concentrations of strychnine in heart and femoral blood were 0.96 and 0.31 mg/L, respectively. Vitreous fluid, bile, urine, liver, and brain specimens contained 0.36 mg/L, 1.17 mg/L, 2.92 mg/L, 4.59 mg/kg, and 0.86 mg/kg strychnine, respectively. No other drugs were detected in any of the samples. The cause of death was attributed to rodenticide poisoning, and the manner of death was suicide.

Inhibition of human Na(v)1.5 sodium channels by strychnine and its analogs.

PubMed

Yuan, Chunhua; Sun, Lirong; Zhang, Meng; Li, Shuji; Wang, Xuemin; Gao, Tianming; Zhu, Xinhong

2011-08-15

Strychnine and brucine from the seeds of the plant Strychnos nux vomica have been shown to have interesting pharmacological effects on several neurotransmitter receptors. In this study, we have characterized the pharmacological properties of strychnine and its analogs on human Na(v)1.5 channels to assess their potential therapeutic advantage in certain arrhythmias. Among the eight alkaloids, only strychnine and icajine exhibited inhibition potency on the Na(v)1.5 channel with the half-maximum inhibition (IC(50)) values of 83.1μM and 104.6μM, respectively. Structure-function analysis indicated that the increased bulky methoxy groups on the phenyl ring or the negatively charged oxygen atom may account for this lack of inhibition on the Na(v)1.5 channel. Strychnine and icajine may bind to the channel by cation-π interactions. The substitution with a large side chain on the phenyl ring or the increased molecular volume may alter the optimized position for the compound close to the binding sites of the channel. Strychnine and icajine bind to the Na(v)1.5 channel with a new mechanism that is different from TTX and local anesthetics. They bind to the outer vestibule of the channel pore with fast association and dissociation rates at resting state. Strychnine and icajine had little effect on steady-state fast inactivation but markedly shifted the slow inactivation of Na(v)1.5 currents toward more hyperpolarized potentials. The property of icajine influencing slow-inactivated state of Na(v)1.5 channel would be potential therapeutic advantages in certain arrhythmias. Copyright © 2011 Elsevier Inc. All rights reserved.

The human bitter taste receptor TAS2R10 is tailored to accommodate numerous diverse ligands.

PubMed

Born, Stephan; Levit, Anat; Niv, Masha Y; Meyerhof, Wolfgang; Behrens, Maik

2013-01-02

Bitter taste is a basic taste modality, required to safeguard animals against consuming toxic substances. Bitter compounds are recognized by G-protein-coupled bitter taste receptors (TAS2Rs). The human TAS2R10 responds to the toxic strychnine and numerous other compounds. The mechanism underlying the development of the broad tuning of some TAS2Rs is not understood. Using comparative modeling, site-directed mutagenesis, and functional assays, we identified residues involved in agonist-induced activation of TAS2R10, and investigated the effects of different substitutions on the receptor's response profile. Most interestingly, mutations in S85(3.29) and Q175(5.40) have differential impact on stimulation with different agonists. The fact that single point mutations lead to improved responses for some agonists and to decreased activation by others indicates that the binding site has evolved to optimally accommodate multiple agonists at the expense of reduced potency. TAS2R10 shares the agonist strychnine with TAS2R46, another broadly tuned receptor. Engineering the key determinants for TAS2R46 activation by strychnine in TAS2R10 caused a loss of response to strychnine, indicating that these paralog receptors display different strychnine-binding modes, which suggests independent acquisition of agonist specificities. This implies that the gene duplication event preceding primate speciation was accompanied by independent evolution of the strychnine-binding sites.

The effects of inferior olive lesion on strychnine seizure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, M.C.; Chung, E.Y.; Van Woert, M.H.

1990-10-01

Bilateral inferior olive lesions, produced by systemic administration of the neurotoxin 3-acetylpyridine (3AP) produce a proconvulsant state specific for strychnine-induced seizures and myoclonus. We have proposed that these phenomena are mediated through increased excitation of cerebellar Purkinje cells, through activation of glutamate receptors, in response to climbing fiber deafferentation. An increase in quisqualic acid (QA)-displaceable ({sup 3}H)AMPA ((RS)-alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid) binding in cerebella from inferior olive-lesioned rats was observed, but no difference in ({sup 3}H)AMPA binding displaced by glutamate, kainic acid (KA) or glutamate diethylester (GDEE) was seen. The excitatory amino acid antagonists GDEE and MK-801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclo-hepten-5,10 imine) were tested asmore » anticonvulsants for strychnine-induced seizures in 3AP inferior olive-lesioned and control rats. Neither drug effected seizures in control rats, however, both GDEE and MK-801 produced a leftward shift in the strychnine-seizure dose-response curve in 3AP inferior olive-lesioned rats. GDEE also inhibited strychnine-induced myoclonus in the lesioned group, while MK-801 had no effect on myoclonus. The decreased threshold for strychnine-induced seizures and myoclonus in the 3AP-inferior olive-lesioned rats may be due to an increase in glutamate receptors as suggested by the ({sup 3}H)AMPA binding data.« less

Fabrication of Fe3O4 Nanoparticle-coalesced Hydroxylated Multi-walled Carbon Nanotubes for the Analysis of Strychnine in Human Serum.

PubMed

Feng, Zufei; Xu, Yuehong; Wei, Shuguang; Zhang, Bao; Guan, Fanglin; Li, Shengbin

2015-01-01

A magnetic carbon nanomaterial for Fe3O4-modified hydroxylated multi-walled carbon nanotubes (Fe3O4-MWCNTs-OH) was prepared by the aggregating effect of Fe3O4 nanoparticles on MWCNTs-OH, and this material was combined with high-performance liquid chromatography (HPLC)/photodiode array detector (PAD) to determine strychnine in human serum samples. Some important parameters that could influence the extraction efficiency of strychnine were optimized, including the extraction time, amounts of Fe3O4-MWCNTs-OH, pH of sample solution, desorption solvent and desorption time. Under optimal conditions, the recoveries of spiked serum samples were between 98.3 and 102.7%, and the relative standard deviations (RSDs) ranged from 0.9 to 5.3%. The correlation coefficient was 0.9997. The LODs and LOQs of strychnine were 6.2 and 20.5 ng mL(-1), at signal-to-noise ratios of 3 and 10, respectively. These experimental results showed that the proposed method is feasible for the analysis of strychnine in serum samples.

Strychnine as Target, Samarium Diiodide as Tool: A Personal Story.

PubMed

Beemelmanns, Christine; Reissig, Hans-Ulrich

2015-10-01

Strychnine stands out from the group of classical natural products as one of the first complex compounds to be isolated in pure form and an extreme challenge to be structurally characterized. It has played a central role in natural product total syntheses and the surge in the development of innovative synthetic methods for many decades. Recently, we have accomplished one of the shortest formal total syntheses of strychnine (in ten steps and 14% overall yield or even shorter in eight steps and 10% overall yield). The evolution of a productive synthetic strategy, as well as the synthetic challenges tackled, are described here in detail, including examples of related transformations. The successful synthetic strategy was inspired by the premise that the core structure could be derived from simple aromatic indole precursors by a reductive SmI2 -induced ketyl-aryl coupling. Other key reactions included a diastereoselective reduction and a regioselective elimination protocol. Altogether one of the shortest syntheses of iso-strychnine and hence of strychnine was established. Copyright © 2015 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strychnine

Integrated Risk Information System (IRIS)

Strychnine ; CASRN 57 - 24 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

[Strychnine poisoning: uncommon, but does still happen].

PubMed

van Berlo-van de Laar, Inge R F; Arbouw, Maurits E L; Bles, Carmen M A

2015-01-01

Acute strychnine poisoning is an uncommon form of intoxication, characterized by severe tonic clonic seizures and tetanus-like contractions while the patient is fully conscious. It can result in respiratory failure, leading to death. A 47-year-old man was admitted to the casualty department 2 hours after self-poisoning with strychnine. The clinical picture consisted of persistent seizures, which were treated with midazolam and propofol. The patient went into respiratory failure and asystole, so intubation and cardiac massage were initiated. Other complications were severe metabolic acidosis, hyperthermia and rhabdomyolysis with renal failure. The treatment consisted of cooling, hyperhydration and intravenous administration of sodium bicarbonate. He was discharged to a mental care institution with no persistent symptoms 11 days later. Early aggressive treatment of a strychnine intoxication can be life-saving. Knowledge of the clinical picture and the right treatment is important. Treatment is primarily focussed on stopping the convulsions and securing the airway.

Concept Definition for the Pest Management Component of the Pollution Abatement Management System (PAMS).

DTIC Science & Technology

1982-01-01

able to obtain * Aluminum phosphide, Bromacil, Carbaryl (Sevin), Chlordane, Chlorpyrifos (Oursban), Diazinon, Dichlorovos (DODYP), Malathion, Paraquat...Pentachloro- phenol (PCP), Propoxur (Baygon), Thiram, strychnine/strychnine sulfate, zinc phosphide, and 2,4-D. 10 sufficient data to respond to

Independent Evolution of Strychnine Recognition by Bitter Taste Receptor Subtypes

PubMed Central

Xue, Ava Yuan; Di Pizio, Antonella; Levit, Anat; Yarnitzky, Tali; Penn, Osnat; Pupko, Tal; Niv, Masha Y.

2018-01-01

The 25 human bitter taste receptors (hT2Rs) recognize thousands of structurally and chemically diverse bitter substances. The binding modes of human bitter taste receptors hT2R10 and hT2R46, which are responsible for strychnine recognition, were previously established using site-directed mutagenesis, functional assays, and molecular modeling. Here we construct a phylogenetic tree and reconstruct ancestral sequences of the T2R10 and T2R46 clades. We next analyze the binding sites in view of experimental data to predict their ability to recognize strychnine. This analysis suggests that the common ancestor of hT2R10 and hT2R46 is unlikely to bind strychnine in the same mode as either of its two descendants. Estimation of relative divergence times shows that hT2R10 evolved earlier than hT2R46. Strychnine recognition was likely acquired first by the earliest common ancestor of the T2R10 clade before the separation of primates from other mammals, and was highly conserved within the clade. It was probably independently acquired by the common ancestor of T2R43-47 before the homo-ape speciation, lost in most T2Rs within this clade, but enhanced in the hT2R46 after humans diverged from the rest of primates. Our findings suggest hypothetical strychnine T2R receptors in several species, and serve as an experimental guide for further study. Improved understanding of how bitter taste receptors acquire the ability to be activated by particular ligands is valuable for the development of sensors for bitterness and for potential toxicity. PMID:29552563

Independent Evolution of Strychnine Recognition by Bitter Taste Receptor Subtypes.

PubMed

Xue, Ava Yuan; Di Pizio, Antonella; Levit, Anat; Yarnitzky, Tali; Penn, Osnat; Pupko, Tal; Niv, Masha Y

2018-01-01

The 25 human bitter taste receptors (hT2Rs) recognize thousands of structurally and chemically diverse bitter substances. The binding modes of human bitter taste receptors hT2R10 and hT2R46, which are responsible for strychnine recognition, were previously established using site-directed mutagenesis, functional assays, and molecular modeling. Here we construct a phylogenetic tree and reconstruct ancestral sequences of the T2R10 and T2R46 clades. We next analyze the binding sites in view of experimental data to predict their ability to recognize strychnine. This analysis suggests that the common ancestor of hT2R10 and hT2R46 is unlikely to bind strychnine in the same mode as either of its two descendants. Estimation of relative divergence times shows that hT2R10 evolved earlier than hT2R46. Strychnine recognition was likely acquired first by the earliest common ancestor of the T2R10 clade before the separation of primates from other mammals, and was highly conserved within the clade. It was probably independently acquired by the common ancestor of T2R43-47 before the homo-ape speciation, lost in most T2Rs within this clade, but enhanced in the hT2R46 after humans diverged from the rest of primates. Our findings suggest hypothetical strychnine T2R receptors in several species, and serve as an experimental guide for further study. Improved understanding of how bitter taste receptors acquire the ability to be activated by particular ligands is valuable for the development of sensors for bitterness and for potential toxicity.

Gustatory receptor 22e is essential for sensing chloroquine and strychnine in Drosophila melanogaster.

PubMed

Poudel, Seeta; Kim, Yunjung; Gwak, Jun-Seok; Jeong, Sangyun; Lee, Youngseok

2017-09-01

Chloroquine, an amino quinolone derivative commonly used as an anti-malarial drug, is known to impart an unpleasant taste. Little research has been done to study chloroquine taste in insects, therefore, we examined both the deterrant properties and mechanisms underlying chloroquine perception in fruit flies. We identified the antifeedant effect of chloroquine by screening 21 gustatory receptor (Grs) mutants through behavioral feeding assays and electrophysiology experiments. We discovered that two molecular sensors, GR22e and GR33a, act as chloroquine receptors, and found that chloroquine-mediated activation of GRNs occurs through S-type sensilla. At the same time, we successfully recapitulated the chloroquine receptor by expressing GR22e in ectopic gustatory receptor neurons. We also found that GR22e forms a part of the strychnine receptor. We suggest that the Drosophila strychnine receptor might have a very complex structure since five different GRs are required for strychnine-induced action potentials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glycine receptor mechanism illuminated by electron cryo-microscopy

PubMed Central

Du, Juan; Lü, Wei; Wu, Shenping; Cheng, Yifan; Gouaux, Eric

2015-01-01

Summary The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of GlyRs has been hindered by a dearth of high-resolution structures. Here we report electron cryo-microscopy structures of the α1 GlyR with strychnine, glycine, or glycine/ivermectin. Strychnine arrests the receptor in an antagonist-bound, closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain ‘wrist’ interface, and leads to rotation of the transmembrane domain toward the pore axis, occluding the ion conduction pathway. These structures illuminate GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors. PMID:26344198

Glycine receptor mechanism elucidated by electron cryo-microscopy.

PubMed

Du, Juan; Lü, Wei; Wu, Shenping; Cheng, Yifan; Gouaux, Eric

2015-10-08

The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders, including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of glycine receptors has been hindered by a lack of high-resolution structures. Here we report electron cryo-microscopy structures of the zebrafish α1 GlyR with strychnine, glycine, or glycine and ivermectin (glycine/ivermectin). Strychnine arrests the receptor in an antagonist-bound closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain 'wrist' interface, and leads to rotation of the transmembrane domain towards the pore axis, occluding the ion conduction pathway. These structures illuminate the GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors.

Determinants of positive cooperativity between strychnine-like allosteric modulators and N-methylscopolamine at muscarinic receptors.

PubMed

Jakubík, Jan; Dolezal, Vladimír

2006-01-01

It has been shown previously that the third extracellular loop (o3) and its vicinity play a critical role in allosteric modulation at muscarinic acetylcholine receptors (mAChRs) (Ellis et al., 1993; Krejçí and Tuçek, 2001; Buller et al., 2002). In this study interaction of four chemically related substances (strychnine, its dimethoxy derivate brucine, precursor for synthesis of strychnine Wieland-Gumlich aldehyde (WGA), and precursor for synthesis of alcuronium propargyl-WGA) with orthosteric antagonist N-methylscopolamine (NMS) was investigated on the M3 subtype of mAChRs mutated at the o3 loop.

Total synthesis of (-)-strychnine.

PubMed

Kaburagi, Yosuke; Tokuyama, Hidetoshi; Fukuyama, Tohru

2004-08-25

Total synthesis of (-)-strychnine is described. Notable features of our synthesis include (1) palladium-catalyzed coupling of the indole and vinyl epoxide moieties, (2) synthesis of the nine-membered cyclic amine derivative from the diol precursor in a one-pot procedure, and (3) transannular cyclization of the nine-membered cyclic amine.

A study of Semen Strychni-induced renal injury and herb-herb interaction of Radix Glycyrrhizae extract and/or Rhizoma Ligustici extract on the comparative toxicokinetics of strychnine and brucine in rats.

PubMed

Gu, Liqiang; Wang, Xiaofan; Liu, Zhenzhen; Ju, Ping; Zhang, Lunhui; Zhang, Yuanyuan; Ma, Bingjie; Bi, Kaishun; Chen, Xiaohui

2014-06-01

Recently, the renal injury caused by Semen strychni and its major toxic constituents, strychnine and brucine, was reported in many clinical cases. Hence, this study was conducted to investigate the renal injury induced by Semen Strychni and the protective effects of Radix Glycyrrhizae and Rhizoma Ligustici. The protective mechanisms were related to the comparative toxicokinetics of strychnine and brucine. Serum and urine uric acid and creatinine were used as renal function markers to evaluate the condition of kidney, and renal injury was directly reflected by histopathological changes. Compared with rats in blank group and protective herb groups, rats in Semen Strychni high-dose group showed significant differences in the results of renal function markers, and various glomerular and tubular degenerations were found in the histopathological study. The decreased AUC (only strychnine) and Cmax, the increased Tmax by Radix Glycyrrhizae and the decreased T1/2 by Radix Glycyrrhizae and Rhizoma Ligustici were found in model groups. Results indicated that high dose of Semen Strychni might induce renal injury. Radix Glycyrrhizae and Rhizoma Ligustici might work together and have effects on the elimination of strychnine and brucine. The protective effects of Radix Glycyrrhizae might also be explained by the slow absorption of the alkaloids. Copyright © 2014 Elsevier Ltd. All rights reserved.

The formal total synthesis of (+/-)-strychnine via a cobalt-mediated [2 + 2 + 2]cycloaddition.

PubMed

Eichberg, M J; Dorta, R L; Lamottke, K; Vollhardt, K P

2000-08-10

A short, highly convergent total synthesis of racemic isostrychnine, and thus strychnine, has been completed. The route involves 14 steps in the longest linear sequence and is highlighted by a cobalt-mediated [2 + 2 + 2]cycloaddition of an alkynylindole nucleus to acetylene.

Black-tailed prairie dog populations one year after treatment with rodenticides

Treesearch

Anthony D. Apa; Daniel W. Uresk; Raymond L. Linder

1990-01-01

Three rodenticide treatments, zinc phosphide with prebait, strychnine with prebait, and strychnine without prebait, were applied to black-tailed prairie dog (Cynomys ludovicianus) colonies in west central South Dakota. Results were compared immediately posttreatment and for one year after application. Zinc phosphide was the most effective for...

Effects of prairie dog rodenticides on deer mice in western South Dakota

Treesearch

Michele S. Deisch; Daniel W. Uresk; Raymond L. Linder

1990-01-01

Mortality of nontarget small mammals was determined after application of three black-tailed prairie dog (Cynomys Zudovicianus) rodenticide treatments (prebaited zinc phosphide, prebaited strychnine, and strychnine alone) in western South Dakota. Immediate (September 1983) and long-term (September 1983 through August 1984) impacts on deer mouse (...

Impacts of black-tailed prairie dog rodenticides on nontarget passerines

Treesearch

Anthony D. Apa; Daniel W. Uresk; Raymond L. Linder

1991-01-01

In 1983 zinc phosphide, strychnine with prebait, and strychnine without prebait were applied to black-tailed prairie dog (Cynomys Zudovicianus) colonies in west central South Dakota. Short-term (four days later) and long-term (one year later) impacts of the rodenticides on Horned Larks (Eremophila alpestris) and other...

Concise total syntheses of (+/-)-strychnine and (+/-)-akuammicine.

PubMed

Sirasani, Gopal; Paul, Tapas; Dougherty, William; Kassel, Scott; Andrade, Rodrigo B

2010-05-21

Concise total syntheses of Strychnos alkaloids strychnine (1) and akuammicine (2) have been realized in 13 and 6 operations, respectively. Key steps include (1) the vinylogous Mannich reaction; (2) a novel, sequential one-pot spirocyclization/intramolecular aza-Baylis-Hillman reaction; and (3) a Heck cyclization. The synthesis of 1 proceeds via the Wieland-Gumlich aldehyde (26).

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2011 CFR

2011-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2014 CFR

2014-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

27 CFR 21.99 - Brucine alkaloid.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., characteristic of strychnine, will be obtained. (d) Sulfate test. No white precipitate is formed that is not... Brucine alkaloid. (a) Identification test. Add a few drops of concentrated nitric acid to about 10 mg of... tetrahydrate melts at 105 °C. while the anhydrous form melts at 178 °C. (c) Strychnine test. Brucine alkaloid...

THE INFLUENCE OF THE SIMULTANEOUS EFFECT OF X-RAY IRRADIATION AND SOME NARCOTICS AND STIMULANTS ON THE MORTALITY OF TADPOLES (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Praslicka, M.; Helona, J.; Havelka, J.

1955-01-01

Tadpoles of Rana esculenta were selected for experiments to ascertain changes in the action of irradiation produced by certain narcotics and by strychnine. The control tadpoles were irradiated with a dose of 27,500 r, as were also tadpoles in a watery solution of one of the following substances: ether (0.1%), ethanol (2 and 2.5%), chloral hydrate (0.3%), avertine (irradiation in water for 5 mins. in 0.1% solution), strychnine (1: 100,000, of the tadpoles irradiated in the watery solution of narcotic substances is in all cases statistically and significantly prolonged in comparison with that in the case of the tadpoles irradiatedmore » in water. Strychnine in a concentration of 1: 100,000, which produced signs of irritation, produced sensitivity to irradiation; in concentrations of 1: 50,000 and 1: 30,000, which produced inhibition, it had a protective effect, in as far as the tadpoles survived the toxic action of the strychnine. It would appear that irradiation intensifies the toxic action of avertine, ether, chloroform, and scopolamine. (auth)« less

Toxic effects of strychnine and strychnine N-oxide on zebrafish embryos.

PubMed

Li, Yu; Qi, Xu; Yang, Yu-Wei; Pan, Yang; Bian, Hui-Min

2014-10-01

The application of strychnine (S) is limited due to its toxicity; strychnine N-oxide (SNO) is a derivative of strychnine. The aim was to employ zebrafish embryos to investigate and compare the developmental toxicity induced by S and SNO. The toxicity of S and SNO was examined through the hatching rate and survival rate. Morphological changes of the zebrafish were observed with a dissecting microscope. Apoptosis was detected through acridine orange (AO) staining and flow cytometry. Apoptotic genes were measured by RT-PCR. Embryo malformation was observed in the embryos exposed to S at 200 μmol·L(-1). When SNO concentration was increased to 1 mmol·L(-1), scoliolosis, and pericardial edema could be seen in some embryos. Results from fluorescence microscopy and flow cytometry analysis showed that S at 200 μmol·L(-1) induced apoptosis, whereas the apoptotic rate in the SNO-treated group (200 μmol·L(-1)) was much lower than that in the S group. RT-PCR analysis showed that p53 mRNA expression and the ratio of Bax/Bcl-2 in the S group were significantly altered compared with the control group (*P < 0.05). Moreover, Bax mRNA expression in both S and SNO group were significantly different from that in the control group (**P < 0.01). These results lead to the conclusion that SNO has significantly lower toxicity than S in zebrafish embryos. Copyright © 2014 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Moles and Mole Control on British Farms, Amenities and Gardens after Strychnine Withdrawal

PubMed Central

Baker, Sandra E.; Ellwood, Stephen A.; Johnson, Paul J.; Macdonald, David W.

2016-01-01

Simple Summary Moles are burrowing mammals that are regarded as pests in Britain, and until 2006 they could legally be killed using strychnine poison. When strychnine was withdrawn there were fears that mole populations would increase. We surveyed farmers, amenity managers and householders about moles and mole control on their land in 2007, post strychnine withdrawal. Kill-trapping was by far the preferred control method used and control may be used more than can be justified by damage levels or the effect of control on damage. Mole traps are unregulated, unlike most other spring traps, and some might not meet current welfare standards. We found no evidence that mole activity had increased since a 1992 survey of farms. Abstract Moles are considered pests in Britain, but this issue has been little studied. Lower welfare standards have been tolerated for moles than for most other managed wild mammal species, as use of both the controversial poison, strychnine, and unregulated traps have been permitted. Strychnine was withdrawn in 2006 and there were fears that mole populations would increase as a result. In 2007, we conducted a comprehensive, nationwide survey of land manager perceptions, opinions and behaviour regarding moles and mole control on farms, amenities and domestic gardens in Britain. We surveyed 2150 land managers (achieving a 59% response rate) and ground-truthed 29 responses. Moles were reported to be present on most farms and amenities, and 13% of gardens, and were more common in lighter soils. Where present, moles were usually considered pests, this being more likely in Wales, Scotland and northern England, on livestock and mixed farms, and on large, high-value amenities, e.g., racecourses and golf courses. Mole control followed similar patterns to mole presence. More control may occur than is economically, and therefore potentially ethically, justified. Control should be more carefully considered and, where necessary, more effectively targeted. Kill-trapping was the favoured recent and future method on farms and amenities, even if strychnine was to be reintroduced; however, because mole traps are currently unregulated, some might not meet current welfare standards if tested. We found no evidence for an increase in moles since a farm questionnaire survey conducted in 1992; this could have wider implications for future wildlife management policy changes. PMID:27338484

Total synthesis of (+/-)-strychnine via a [4 + 2]-cycloaddition/rearrangement cascade.

PubMed

Zhang, Hongjun; Boonsombat, Jutatip; Padwa, Albert

2007-01-18

A new strategy for the synthesis of the Strychnos alkaloid (+/-)-strychnine has been developed and is based on an intramolecular [4 + 2]-cycloaddition/rearrangement cascade of an indolyl-substituted amidofuran. The critical D-ring was assembled by an intramolecular palladium-catalyzed enolate-driven cross-coupling of an N-tethered vinyl iodide. [reaction: see text].

Total Synthesis of (±)-Strychnine via a [4+2]-Cycloaddition/Rearrangement Cascade

PubMed Central

Zhang, Hongjun; Boonsombat, Jutatip

2008-01-01

A new strategy for the synthesis of the Strychnos alkaloid (±)-strychnine has been developed and is based on an intramolecular [4+2]-cycloaddition/rearrangement cascade of an indolyl substituted amidofuran. The critical D-ring was assembled by an intramolecular palladium catalyzed enolate-driven cross-coupling of an N-tethered vinyl iodide. PMID:17217284

Effects of two prairie dog rodenticides on ground-dwelling invertebrates in western South Dakota

Treesearch

Michele S. Deisch; Daniel W. Uresk; Raymond L. Linder

1989-01-01

Immediate and long-term effects of 3 rodenticide treatments on nontarget invertebrates were evaluated on prairie dog colonies. Immediate impacts indicated zinc phosphide reduced ants, strychnine alone reduced wolf spiders, and prebaited strychnine had no impacts. Long-term changes showed increases in wolf spiders and ground beetles and densities were contributed to...

Glycine aggravates ischemia reperfusion-induced acute kidney injury through N-Methyl-D-Aspartate receptor activation in rats.

PubMed

Arora, Shiyana; Kaur, Tajpreet; Kaur, Anudeep; Singh, Amrit Pal

2014-08-01

The present study was designed to investigate the role of glycine in ischemia reperfusion-induced acute kidney injury (AKI) in rats. The AKI was induced in rats by occluding renal pedicles for 40 min followed by reperfusion for 24 h. The AKI was assessed by measuring creatinine clearance, blood urea nitrogen, plasma uric acid, potassium, fractional excretion of sodium, and microproteinuria. The oxidative stress in renal tissues was assessed by quantification of myeloperoxidase activity, thiobarbituric acid-reactive substances, superoxide anion generation, and reduced glutathione level. Glycine (100, 200, and 400 mg/kg, i.p.) was administered to rats 30 min before subjecting to AKI. The glycinergic receptor blocker, strychnine (0.75 mg/kg i.p.), and glycine-binding site blocker at N-methyl-D-aspartate (NMDA) receptor, kynurenic acid (300 and 600 mg/kg i.p.), were used in the present study. The ischemia reperfusion induced AKI as witnessed by significant change in plasma, urinary, and tissue parameters employed in the present study. Glycine treatment increased ischemia reperfusion-induced AKI. The treatment with strychnine did not show any protection, whereas kynurenic acid ameliorated renal ischemia reperfusion-induced AKI. The results obtained in present study suggest that glycine increases ischemia reperfusion-induced renal damage through NMDA receptor agonism rather than strychnine-sensitive glycinergic receptors. Hence, it is concluded that glycine aggravates ischemia reperfusion-induced AKI. In addition, the activation of strychnine-insensitive glycine-binding site of NMDA receptors is responsible for its renal-damaging effect rather than strychnine-sensitive glycinergic receptors.

A population model of the impact of a rodenticide containing strychnine on Great Basin Gophersnakes (Pituophis catenifer deserticola).

PubMed

Bishop, Christine A; Williams, Kathleen E; Kirk, David A; Nantel, Patrick; Reed, Eric; Elliott, John E

2016-09-01

Strychnine is a neurotoxin and an active ingredient in some rodenticides which are placed in burrows to suppress pocket gopher (Thomomys talpoides) populations in range and crop land in western North America. The population level impact was modelled of the use of strychnine-based rodenticides on a non-target snake species, the Great Basin Gophersnake (Pituophis catenifer deserticola), which is a predator of pocket gopher and a Species at Risk in Canada. Using information on population density, demographics, and movement and habitat suitability for the Gophersnake living in an agricultural valley in BC, Canada, we estimated the impact of the poisoning of adult snakes on the long-term population size. To determine the area where Gophersnakes could be exposed to strychnine, we used vendor records of a rodenticide, and quantified the landcover areas of orchards and vineyards where the compound was most commonly applied. GIS analysis determined the areas of overlap between those agricultural lands and suitable habitats used by Gophersnakes. Stage-based population matrix models revealed that in a low density (0.1/ha) population scenario, a diet of one pocket gopher per year wherein 10 % of them carried enough strychnine to kill an adult snake could cause the loss of 2 females annually from the population and this would reduce the population by 35.3 % in 25 years. Under the same dietary exposure, up to 35 females could die per year in a high density (0.4/ha) population which would result in a loss of 50 % of adults in 25 years.

Laminar distribution of GABAA- and glycine-receptor mediated tonic inhibition in the dorsal horn of the rat lumbar spinal cord: effects of picrotoxin and strychnine on expression of Fos-like immunoreactivity.

PubMed

Cronin, John N; Bradbury, Elizabeth J; Lidierth, Malcolm

2004-11-01

Inhibitory mechanisms are essential in suppressing the development of allodynia and hyperalgesia in the normal animal and there is evidence that loss of inhibition can lead to the development of neuropathic pain. We used Fos expression to map the distribution of tonically inhibited cells in the healthy rat lumbar spinal cord. In a control group, Fos-like immunoreactive (Fos-LI) cells were rare, averaging 7.5+/-2.2 cells (mean+/-SEM; N=13 sections) per 20 microm thick section of dorsal horn. This rose to 103+/-11 (mean+/-SEM; N=20) in picrotoxin-treated rats and to 88+/-11 (mean+/-SEM; N=18) in strychnine-treated rats. These changes were significant (ANOVA; P<0.001). There were marked regional variations in the distribution of Fos-LI cells between picrotoxin- and strychnine-treated animals. Picrotoxin induced a significant increase in the number of Fos-LI cells throughout the dorsal horn (lamina I-VI) while strychnine significantly elevated Fos-like immunoreactivity only in deep laminae (III-VI). For both picrotoxin and strychnine, the increase in Fos-like immunoreactivity peaked in lamina V (at 3579+/-319 and 3649+/-375% of control, respectively; mean+/-SEM) but for picrotoxin an additional peak was observed in the outer part of lamina II (1959+/-196%). Intrathecal administration of both GABAA and glycine receptor antagonists has been shown elsewhere to induce tactile allodynia. The present data suggest that this allodynia could arise due to blockade of tonic GABAA and glycine-receptor mediated inhibition in the deep dorsal horn. GABAA antagonists also induce hypersensitivity to noxious inputs. The blockade of tonic inhibition in the superficial dorsal horn shown here may underlie this hyperalgesia.

Synthesis and characterization of Ag doped ZnS quantum dots for enhanced photocatalysis of Strychnine asa poison: Charge transfer behavior study by electrochemical impedance and time-resolved photoluminescence spectroscopy.

PubMed

Gupta, Vinod Kumar; Fakhri, Ali; Azad, Mona; Agarwal, Shilpi

2018-01-15

In this study, the photocatalytic degradation of Strychnine was investigated by ZnS quantum dots and doped with silver in UV systems. ZnS and Ag-ZnS quantum dots were synthesized by chemical method and characterized by powder X-ray diffraction, transmission electron microscopy, UV-vis spectra and photoluminescence. The charge transfer process on the semicon-ductor/electrolyte interface was investigated via electrochemical impedance spectroscopy (EIS) and time-resolved photoluminescence. The average diameters of ZnS and Ag doped ZnS QDs were 3.0-5.0nm and 3.0-5.3nm, respectively. The band gap of ZnS and Ag-ZnS QDs was computed as 3.47 and 3.1eV, respectively. The surface area values of ZnS and Ag-ZnS QDs have been found as 78.25 and 89.54m 2 /g, respectively. The influences of key operating parameters such as initial pH, catalyst dosage, UV radiation intensity, reaction time as well as the effect of initial Strychnine concentration on mineralization extents were studied. The results of the study showed that the maximum removal efficiency of Strychnine had been achieved by un-doped and Ag-doped ZnS QDs at radiation intensity of 100W/m 2 , at time of 60min, pH of 3 and initial Strychnine concentration of 20mg/ml. Also the observations clearly showed that the photocatalysis process with Ag doped ZnS QDs are more effective than un-doped ZnS QDs. Copyright © 2017 Elsevier Inc. All rights reserved.

Asparagine, valine, and threonine in the third extracellular loop of muscarinic receptor have essential roles in the positive cooperativity of strychnine-like allosteric modulators.

PubMed

Jakubík, J; Krejcí, A; Dolezal, V

2005-05-01

We have investigated allosteric interactions of four closely related strychnine-like substances: Wieland-Gumlich aldehyde (WGA), propargyl Wieland-Gumlich aldehyde, strychnine, and brucine with N-methylscopolamine (NMS) on M(3) subtype of muscarinic receptor genetically modified in the second or the third extracellular loop to corresponding loops of M(2) subtype (M(3)o2 and M(3)o3 chimera). The M(3)o2 chimeric receptor The exhibited no change in either affinity of strychnine, brucine, and WGA or in cooperativity of brucine or WGA, whereas both parameters for propargyl-WGA changed. In contrast, there was a change in affinity of all tested modulators (except for brucine) and in their cooperativity in the M(3)o3 chimera. Directions of affinity changes in both chimeras were always toward values of the donor M(2) subtype, but changes in cooperativity were variable. Compared with the native M(3) receptor, strychnine displayed a slight increase in positive cooperativity and propargyl-WGA a robust decrease in negative cooperativity at M(3)o2 chimera. Similar changes were found in the M(3)o3 chimera. Interestingly, cooperativity of brucine and WGA at the M(3)o3 chimera changed from negative to positive. This is the first evidence of constitution of positive cooperativity of WGA by switching sequences of two parental receptors, both exhibiting negative cooperativity. Gradual replacement of individual amino acids revealed that only three residues (NVT of the o3 loop of the M(2) receptor) are involved in this effect. Data suggest that these amino acids are essential for propagation of a conformation change resulting in positive cooperativity induced by these modulators.

Brief Embryonic Strychnine Exposure in Zebrafish Causes Long-Term Adult Behavioral Impairment with Indications of Embryonic Synaptic Changes

PubMed Central

Roy, Nicole M.; Arpie, Brianna; Lugo, Joseph; Linney, Elwood; Levin, Edward D.; Cerutti, Daniel

2015-01-01

Zebrafish provide a powerful model of the impacts of embryonic toxicant exposure on neural development that may result in long-term behavioral dysfunction. In this study, zebrafish embryos were treated with 1.5 mM strychnine for short embryonic time windows to induce transient changes in inhibitory neural signaling, and were subsequently raised in untreated water until adulthood. PCR analysis showed indications that strychnine exposure altered expression of some genes related to glycinergic, GABAergic and glutamatergic neuronal synapses during embryonic development. In adulthood, treated fish showed significant changes in swimming speed and tank diving behavior compared to controls. Taken together, these data show that a short embryonic exposure to a neurotoxicant can alter development of neural synapses and lead to changes in adult behavior. PMID:23022260

Brief embryonic strychnine exposure in zebrafish causes long-term adult behavioral impairment with indications of embryonic synaptic changes.

PubMed

Roy, Nicole M; Arpie, Brianna; Lugo, Joseph; Linney, Elwood; Levin, Edward D; Cerutti, Daniel

2012-01-01

Zebrafish provide a powerful model of the impacts of embryonic toxicant exposure on neural development that may result in long-term behavioral dysfunction. In this study, zebrafish embryos were treated with 1.5mM strychnine for short embryonic time windows to induce transient changes in inhibitory neural signaling, and were subsequently raised in untreated water until adulthood. PCR analysis showed indications that strychnine exposure altered expression of some genes related to glycinergic, GABAergic and glutamatergic neuronal synapses during embryonic development. In adulthood, treated fish showed significant changes in swimming speed and tank diving behavior compared to controls. Taken together, these data show that a short embryonic exposure to a neurotoxicant can alter development of neural synapses and lead to changes in adult behavior. Copyright © 2012 Elsevier Inc. All rights reserved.

An Evaluation of the PCB-TOX-SPOT Water Toxicity Test

DTIC Science & Technology

2011-09-15

Guidelines (70 kg person, 15 liter [L]/day consumption), when available; 1 year MEG for copper, fluoroacetate, and strychnine ; < 7 day MEG for nicotine... strychnine ; < 7 day MEG for nicotine; fenamiphos MEG estimated from terbufos (Richards, personal communication), b mg/L c Data from FOUO Widder et al...Ulitzur S. 1977. Control of luciferase synthesis in a newly isolated strain of Photobacterium leiognathi. Arch Microbiol.,Dec 15;115(3):347-51

Use of Strychnos nux-vomica (Azraqi) seeds in Unani system of medicine: role of detoxification.

PubMed

Akbar, Seema; Khan, Shamshad A; Masood, Akbar; Iqbal, M

2010-01-01

Some plants used in Unani system of medicine are toxic, even deadly poisonous. The drugs having such plants as their components are detoxified before they are dispensed to the patients. One such drug, capsule Hudar, has Strychnos nux-vomica L. (Azraqi) seeds as one of its components and is very effectively used to elevate blood pressure. Ancient manuscripts describe many methods of its detoxification. It has been found that the detoxification processes studied reduce the strychnine content, as determined either by using uv-vis spectrophotometer or HPLC, present in Strychnos nux vomica seeds which is responsible for Strychnos nux vomica toxicity. The decrease in strychnine amount was best when the seeds were immersed for detoxification in excess of water for 5 days, in milk for 2 days followed by their boiling in milk. Strychnine in small amounts has been reported to give subjective feeling of stimulation.

Differentiated human midbrain-derived neural progenitor cells express excitatory strychnine-sensitive glycine receptors containing α2β subunits.

PubMed

Wegner, Florian; Kraft, Robert; Busse, Kathy; Härtig, Wolfgang; Ahrens, Jörg; Leffler, Andreas; Dengler, Reinhard; Schwarz, Johannes

2012-01-01

Human fetal midbrain-derived neural progenitor cells (NPCs) may deliver a tissue source for drug screening and regenerative cell therapy to treat Parkinson's disease. While glutamate and GABA(A) receptors play an important role in neurogenesis, the involvement of glycine receptors during human neurogenesis and dopaminergic differentiation as well as their molecular and functional characteristics in NPCs are largely unknown. Here we investigated NPCs in respect to their glycine receptor function and subunit expression using electrophysiology, calcium imaging, immunocytochemistry, and quantitative real-time PCR. Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro. Pharmacological and molecular analyses indicate a predominance of glycine receptor heteromers containing α2β subunits. Intracellular calcium measurements of differentiated NPCs suggest that glycine evokes depolarisations mediated by strychnine-sensitive glycine receptors and not by D-serine-sensitive excitatory glycine receptors. Culturing NPCs with additional glycine, the glycine-receptor antagonist strychnine, or the Na(+)-K(+)-Cl(-) co-transporter 1 (NKCC1)-inhibitor bumetanide did not significantly influence cell proliferation and differentiation in vitro. These data indicate that NPCs derived from human fetal midbrain tissue acquire essential glycine receptor properties during neuronal maturation. However, glycine receptors seem to have a limited functional impact on neurogenesis and dopaminergic differentiation of NPCs in vitro.

Differentiated Human Midbrain-Derived Neural Progenitor Cells Express Excitatory Strychnine-Sensitive Glycine Receptors Containing α2β Subunits

PubMed Central

Wegner, Florian; Kraft, Robert; Busse, Kathy; Härtig, Wolfgang; Ahrens, Jörg; Leffler, Andreas; Dengler, Reinhard; Schwarz, Johannes

2012-01-01

Background Human fetal midbrain-derived neural progenitor cells (NPCs) may deliver a tissue source for drug screening and regenerative cell therapy to treat Parkinson’s disease. While glutamate and GABAA receptors play an important role in neurogenesis, the involvement of glycine receptors during human neurogenesis and dopaminergic differentiation as well as their molecular and functional characteristics in NPCs are largely unknown. Methodology/Principal Findings Here we investigated NPCs in respect to their glycine receptor function and subunit expression using electrophysiology, calcium imaging, immunocytochemistry, and quantitative real-time PCR. Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro. Pharmacological and molecular analyses indicate a predominance of glycine receptor heteromers containing α2β subunits. Intracellular calcium measurements of differentiated NPCs suggest that glycine evokes depolarisations mediated by strychnine-sensitive glycine receptors and not by D-serine-sensitive excitatory glycine receptors. Culturing NPCs with additional glycine, the glycine-receptor antagonist strychnine, or the Na+-K+-Cl− co-transporter 1 (NKCC1)-inhibitor bumetanide did not significantly influence cell proliferation and differentiation in vitro. Conclusions/Significance These data indicate that NPCs derived from human fetal midbrain tissue acquire essential glycine receptor properties during neuronal maturation. However, glycine receptors seem to have a limited functional impact on neurogenesis and dopaminergic differentiation of NPCs in vitro. PMID:22606311

Extrinsic factors regulate partial agonist efficacy of strychnine-sensitive glycine receptors

PubMed Central

Farroni, Jeffrey S; McCool, Brian A

2004-01-01

Background Strychnine-sensitive glycine receptors in many adult forebrain regions consist of alpha2 + beta heteromeric channels. This subunit composition is distinct from the alpha1 + beta channels found throughout the adult spinal cord. Unfortunately, the pharmacology of forebrain alpha2beta receptors are poorly defined compared to 'neonatal' alpha2 homomeric channels or 'spinal' alpha1beta heteromers. In addition, the pharmacologic properties of native alpha2beta glycine receptors have been generally distinct from receptors produced by heterologous expression. To identify subtype-specific pharmacologic tools for the forebrain alpha2beta receptors, it is important to identify a heterologous expression system that closely resembles these native glycine-gated chloride channels. Results While exploring pharmacological properties of alpha2beta glycine receptors compared to alpha2-homomers, we found that distinct heterologous expression systems appeared to differentially influence partial agonist pharmacology. The β-amino acid taurine possessed 30–50% efficacy for alpha2-containing receptor isoforms when expressed in HEK 293 cells. However, taurine efficacy was dramatically reduced in L-cell fibroblasts. Similar results were obtained for β-alanine. The efficacy of these partial agonists was also strongly reduced by the beta subunit. There were no significant differences in apparent strychnine affinity values calculated from concentration-response data between expression systems or subunit combinations. Nor did relative levels of expression correlate with partial agonist efficacy when compared within or between several different expression systems. Finally, disruption of the tubulin cytoskeleton reduced the efficacy of partial agonists in a subunit-dependent, but system-independent, fashion. Conclusions Our results suggest that different heterologous expression systems can dramatically influence the agonist pharmacology of strychnine-sensitive glycine receptors. In the systems examine here, these effects are independent of both absolute expression level and any system-related alterations in the agonist binding site. We conclude that complex interactions between receptor composition and extrinsic factors may play a significant role in determining strychnine-sensitive glycine receptor partial agonist pharmacology. PMID:15301692

Extrinsic factors regulate partial agonist efficacy of strychnine-sensitive glycine receptors.

PubMed

Farroni, Jeffrey S; McCool, Brian A

2004-08-09

Strychnine-sensitive glycine receptors in many adult forebrain regions consist of alpha2 + beta heteromeric channels. This subunit composition is distinct from the alpha1 + beta channels found throughout the adult spinal cord. Unfortunately, the pharmacology of forebrain alpha2beta receptors are poorly defined compared to 'neonatal' alpha2 homomeric channels or 'spinal' alpha1beta heteromers. In addition, the pharmacologic properties of native alpha2beta glycine receptors have been generally distinct from receptors produced by heterologous expression. To identify subtype-specific pharmacologic tools for the forebrain alpha2beta receptors, it is important to identify a heterologous expression system that closely resembles these native glycine-gated chloride channels. While exploring pharmacological properties of alpha2beta glycine receptors compared to alpha2-homomers, we found that distinct heterologous expression systems appeared to differentially influence partial agonist pharmacology. The beta-amino acid taurine possessed 30-50% efficacy for alpha2-containing receptor isoforms when expressed in HEK 293 cells. However, taurine efficacy was dramatically reduced in L-cell fibroblasts. Similar results were obtained for beta-alanine. The efficacy of these partial agonists was also strongly reduced by the beta subunit. There were no significant differences in apparent strychnine affinity values calculated from concentration-response data between expression systems or subunit combinations. Nor did relative levels of expression correlate with partial agonist efficacy when compared within or between several different expression systems. Finally, disruption of the tubulin cytoskeleton reduced the efficacy of partial agonists in a subunit-dependent, but system-independent, fashion. Our results suggest that different heterologous expression systems can dramatically influence the agonist pharmacology of strychnine-sensitive glycine receptors. In the systems examine here, these effects are independent of both absolute expression level and any system-related alterations in the agonist binding site. We conclude that complex interactions between receptor composition and extrinsic factors may play a significant role in determining strychnine-sensitive glycine receptor partial agonist pharmacology.

Gustatory detection of tetrodotoxin and saxitoxin, and its competitive inhibition by quinine and strychnine in freshwater fishes.

PubMed

Hara, Toshiaki J

2011-01-01

Fish detect extremely low levels of marine toxins tetrodotoxin (TTX) and saxitoxin (STX) via the specialized gustatory receptor(s). Physiological and pharmacological studies show that receptor(s) for TTX and STX are distinct from those which detect feeding stimulant amino acids and bile acids, and that TTX and STX do not share the same receptor populations, while interacting with quinine and strychnine in a competitive fashion suggestive of an antidotal relationship.

Gustatory Detection of Tetrodotoxin and Saxitoxin, and Its Competitive Inhibition by Quinine and Strychnine in Freshwater Fishes

PubMed Central

Hara, Toshiaki J.

2011-01-01

Fish detect extremely low levels of marine toxins tetrodotoxin (TTX) and saxitoxin (STX) via the specialized gustatory receptor(s). Physiological and pharmacological studies show that receptor(s) for TTX and STX are distinct from those which detect feeding stimulant amino acids and bile acids, and that TTX and STX do not share the same receptor populations, while interacting with quinine and strychnine in a competitive fashion suggestive of an antidotal relationship. PMID:22163186

beta-Alanine elevates dopamine levels in the rat nucleus accumbens: antagonism by strychnine.

PubMed

Ericson, Mia; Clarke, Rhona B C; Chau, PeiPei; Adermark, Louise; Söderpalm, Bo

2010-04-01

Glycine receptors (GlyRs) in the nucleus accumbens (nAc) have recently been suggested to be involved in the reinforcing and dopamine-elevating properties of ethanol via a neuronal circuitry involving the VTA. Apart from ethanol, both glycine and taurine have the ability to modulate dopamine output via GlyRs in the same brain region. In the present study, we wanted to explore whether yet another endogenous ligand for the GlyR, beta-alanine, had similar effects. To this end, we monitored dopamine in the nAc by means of in vivo microdialysis and found that local perfusion of beta-alanine increased dopamine output. In line with previous observations investigating ethanol, glycine and taurine, the competitive GlyR antagonist strychnine completely blocked the dopamine elevation. The present results suggest that beta-alanine has the ability to modulate dopamine levels in the nAc via strychnine-sensitive GlyRs, and are consistent with previous studies suggesting the importance of this receptor for modulating dopamine output.

Strychnine blocks transient but not sustained inhibition in mudpuppy retinal ganglion cells.

PubMed Central

Belgum, J H; Dvorak, D R; McReynolds, J S

1984-01-01

Transient and sustained inhibitory synaptic inputs to on-centre, off-centre, and on-off ganglion cells in the mudpuppy retina were studied using intracellular recording in the superfused eye-cup preparation. When chemical transmission was blocked with 4 mM-Co2+, application of either glycine or gamma-aminobutyric acid (GABA) caused a hyperpolarization and conductance increase in all ganglion cells. For both amino acids, the responses were dose dependent in the range 0.05-10 mM, with a half-maximal response at about 0.7 mM. Glycine and GABA sensitivities were very similar in all three types of ganglion cells. The response to applied glycine was selectively antagonized by 10(-5) M-strychnine and the response to applied GABA was selectively antagonized by 10(-5) M-picrotoxin. In all ganglion cells, 10(-5) M-strychnine eliminated the transient inhibitory events which occur at the onset and termination of a light stimulus. The block of transient inhibition was associated with a relative depolarization of membrane potential and decrease in conductance at these times. Strychnine had no effect on membrane potential or conductance in darkness or during sustained inhibitory responses to light. Picrotoxin (10(-5) M) did not block transient inhibitory events in any ganglion cells, but did affect other components of their responses. The results suggest that in all three classes of ganglion cells transient inhibition, but not sustained inhibition, may be mediated by glycine or a closely related substance. PMID:6481635

Taurine induces anti-anxiety by activating strychnine-sensitive glycine receptor in vivo.

PubMed

Zhang, Cheng Gao; Kim, Sung-Jin

2007-01-01

Taurine has a variety of actions in the body such as cardiotonic, host-defensive, radioprotective and glucose-regulatory effects. However, its action in the central nervous system remains to be characterized. In the present study, we tested to see whether taurine exerts anti-anxiety effects and to explore its mechanism of anti-anxiety activity in vivo. The staircase test and elevated plus maze test were performed to test the anti-anxiety action of taurine. Convulsions induced by strychnine, picrotoxin, yohimbine and isoniazid were tested to explore the mechanism of anti-anxiety activity of taurine. The Rotarod test was performed to test muscle relaxant activity and the passive avoidance test was carried out to test memory activity in response to taurine. Taurine (200 mg/kg, p.o.) significantly reduced rearing numbers in the staircase test while it increased the time spent in the open arms as well as the number of entries to the open arms in the elevated plus maze test, suggesting that it has a significant anti-anxiety activity. Taurine's action could be due to its binding to and activating of strychnine-sensitive glycine receptor in vivo as it inhibited convulsion caused by strychnine; however, it has little effect on picrotoxin-induced convulsion, suggesting its anti-anxiety activity may not be linked to GABA receptor. It did not alter memory function and muscle activity. Taken together, these results suggest that taurine could be beneficial for the control of anxiety in the clinical situations. Copyright (c) 2007 S. Karger AG, Basel.

Evidence for strychnine-sensitive glycine receptors in human amygdala.

PubMed

Dudeck, O; Lübben, S; Eipper, S; Knörle, R; Kirsch, M; Honegger, J; Zentner, J; Feuerstein, T J

2003-09-01

Recent studies suggested the existence of strychnine-sensitive glycine-receptors in mammalian amygdala. In the present study, we investigated the amino acid concentrations as well as immunocytochemical and pharmacological properties of glycine-receptors in fresh human amygdala tissue obtained from epilepsy surgery. High pressure liquid chromatography revealed a considerable amount of glycine and its precursors and glycine-receptors agonists L-serine and taurine in this tissue. Immunohistochemistry using the monoclonal antibody mAb4a, recognizing an epitope common to all alpha-subunit variants of glycine receptors, displayed a specific labeling at the soma and on proximal dendrites of mostly tripolar, large-sized neurons of irregular distribution and arrangement. To elucidate the pharmacological properties of the glycine-receptors found slices of human amygdala were preloaded with [(3)H]-choline and superfused. Glycine induced an overflow of [(3)H]-acetylcholine, which was inhibited by strychnine in a concentration-dependent manner. Furthermore, the glycine-induced release of [(3)H]-acetylcholine was significantly inhibited by furosemide, indicating glycine-induced actions to be attributed to chloride channels. These actions of glycine were not influenced by MK-801, D-CP-Pene or bicuculline. Thus, the effects of glycine did not seem to be mediated through NMDA or GABA receptors. These observations indicate that strychnine-sensitive, chloride-conducting glycine receptors, which elicit the release of [(3)H]-acetylcholine, are present at the soma and on proximal dendrites of neurons in human amygdala. It is hypothesized that glycine may display a regulatory role in amygdaloid functions, probably via cholinergic interneurons.

Effects of Chronic Ethanol Consumption on Rat GABAA and Strychnine-sensitive Glycine Receptors Expressed by Lateral/Basolateral Amygdala Neurons

PubMed Central

McCool, Brian A.; Frye, Gerald D.; Pulido, Marisa D.; Botting, Shaleen K.

2010-01-01

It is well known that the anxiolytic potential of ethanol is maintained during chronic exposure. We have confirmed this using a light-dark box paradigm following chronic ethanol ingestion via a liquid diet. However, cessation from chronic ethanol exposure is known to cause severe withdrawal anxiety. These opposing effects on anxiety likely result from neuro-adaptations of neurotransmitter systems within the brain regions regulating anxiety. Recent work highlights the importance of amygdala ligand-gated chloride channels in the expression of anxiety. We have therefore examined the effects of chronic ethanol exposure on GABAA and strychnine-sensitive glycine receptors expressed by acutely isolated adult rat lateral/basolateral amygdala neurons. Chronic ethanol exposure increased the functional expression of GABAA receptors in acutely isolated basolateral amygdala neurons without altering strychnine-sensitive glycine receptors. Neither the acute ethanol nor benzodiazepine sensitivity of either receptor system was affected. We explored the likelihood that subunit composition might influence each receptor’s response to chronic ethanol. Importantly, when expressed in a mammalian heterologous system, GABAA receptors composed of unique α subunits were differentially sensitive to acute ethanol. Likewise, the presence of the β subunit appeared to influence the acute ethanol sensitivity of glycine receptors containing the α2 subunit. Our results suggest that the facilitation of GABAA receptors during chronic ethanol exposure may help explain the maintenance of ethanol’s anti-anxiety effects during chronic ethanol exposure. Furthermore, the subunit composition of GABAA and strychnine-sensitive glycine receptors may ultimately influence the response of each system to chronic ethanol exposure. PMID:12560122

Effects of chronic ethanol consumption on rat GABA(A) and strychnine-sensitive glycine receptors expressed by lateral/basolateral amygdala neurons.

PubMed

McCool, Brian A; Frye, Gerald D; Pulido, Marisa D; Botting, Shaleen K

2003-02-14

It is well known that the anxiolytic potential of ethanol is maintained during chronic exposure. We have confirmed this using a light-dark box paradigm following chronic ethanol ingestion via a liquid diet. However, cessation from chronic ethanol exposure is known to cause severe withdrawal anxiety. These opposing effects on anxiety likely result from neuro-adaptations of neurotransmitter systems within the brain regions regulating anxiety. Recent work highlights the importance of amygdala ligand-gated chloride channels in the expression of anxiety. We have therefore examined the effects of chronic ethanol exposure on GABA(A) and strychnine-sensitive glycine receptors expressed by acutely isolated adult rat lateral/basolateral amygdala neurons. Chronic ethanol exposure increased the functional expression of GABA(A) receptors in acutely isolated basolateral amygdala neurons without altering strychnine-sensitive glycine receptors. Neither the acute ethanol nor benzodiazepine sensitivity of either receptor system was affected. We explored the likelihood that subunit composition might influence each receptor's response to chronic ethanol. Importantly, when expressed in a mammalian heterologous system, GABA(A) receptors composed of unique alpha subunits were differentially sensitive to acute ethanol. Likewise, the presence of the beta subunit appeared to influence the acute ethanol sensitivity of glycine receptors containing the alpha(2) subunit. Our results suggest that the facilitation of GABA(A) receptors during chronic ethanol exposure may help explain the maintenance of ethanol's anti-anxiety effects during chronic ethanol exposure. Furthermore, the subunit composition of GABA(A) and strychnine-sensitive glycine receptors may ultimately influence the response of each system to chronic ethanol exposure.

Bicuculline and strychnine suppress the mesencephalic locomotor region-induced inhibition of group III muscle afferent input to the dorsal horn.

PubMed

Degtyarenko, A M; Kaufman, M P

2003-01-01

We examined the effect of iontophoretic application of bicuculline methiodide and strychnine hydrochloride on the mesencephalic locomotor region (MLR)-induced inhibition of dorsal horn cells in paralyzed cats. The activity of 60 dorsal horn cells was recorded extracellularly in laminae I, II, V-VII of spinal segments L7-S1. Each of the cells was shown to receive group III muscle afferent input as demonstrated by their responses to electrical stimulation of the tibial nerve (mean latency and threshold of activation: 20.1+/-6.4 ms and 15.2+/-1.4 times motor threshold, respectively). Electrical stimulation of the MLR suppressed transmission in group III muscle afferent pathways to dorsal horn cells. Specifically the average number of impulses generated by the dorsal horn neurons in response to a single pulse applied to the tibial nerve was decreased by 78+/-2.8% (n=60) during the MLR stimulation. Iontophoretic application (10-50 nA) of bicuculline and strychnine (5-10 mM) suppressed the MLR-induced inhibition of transmission of group III afferent input to laminae I and II cells by 69+/-5% (n=10) and 29+/-7% (n=7), respectively. Likewise, bicuculline and strychnine suppressed the MLR-induced inhibition of transmission of group III afferent input to lamina V cells by 59+/-13% (n=14) and 39+/-11% (n=10), respectively. Our findings raise the possibility that GABA and glycine release onto dorsal horn neurons in the spinal cord may play an important role in the suppression by central motor command of thin fiber muscle afferent-reflex pathways.

Hyperekplexia mutation R271L of alpha1 glycine receptors potentiates allosteric interactions of nortropeines, propofol and glycine with [3H]strychnine binding.

PubMed

Maksay, Gábor; Bíró, Tímea; Laube, Bodo; Nemes, Péter

2008-01-01

Human alpha1 and hyperekplexia mutant alpha1(R271L) glycine receptors (GlyRs) were transiently expressed in human embryonic kidney 293 cells for [3H]strychnine binding. Binding parameters were determined using a ternary allosteric model. The hyperekplexia mutation increased the positive cooperativity of 0.3 mM propofol and glycine binding by about six times: the cooperativity factor beta was 0.26 for alpha1 GlyRs and 0.04 for alpha1(R271L) GlyRs. Thus, propofol restored the potency of glycine impaired by the mutation. Five nortropeines, i.e. substituted benzoates of nortropine and a new compound, nortropisetron were prepared and also examined on [3H]strychnine binding. They showed nanomolar displacing potencies amplified by the hyperekplexia mutation. The affinity of nor-O-zatosetron (2.6 nM) is one of the highest reported for GlyRs. This binding test offers an in vitro method to evaluate agents against neurological disorders associated with inherited mutations of GlyRs.

A non-ionotropic activity of NMDA receptors contributes to glycine-induced neuroprotection in cerebral ischemia-reperfusion injury.

PubMed

Chen, Juan; Hu, Rong; Liao, Huabao; Zhang, Ya; Lei, Ruixue; Zhang, Zhifeng; Zhuang, Yang; Wan, Yu; Jin, Ping; Feng, Hua; Wan, Qi

2017-06-15

NMDA receptor (NMDAR) is known for its ionotropic function. But recent evidence suggests that NMDAR also has a non-ionotropic property. To determine the role of non-ionotropic activity of NMDARs in clinical relevant conditions, we tested the effect of glycine, a co-agonist of NMDARs, in rat middle cerebral artery occlusion (MCAO), an animal model of cerebral ischemia-reperfusion injury after the animals were injected with the NMDAR channel blocker MK-801 and the glycine receptor antagonist strychnine. We show that glycine reduces the infarct volume in the brain of ischemic stroke animals pre-injected with MK-801 and strychnine. The effect of glycine is sensitive to the antagonist of glycine-GluN1 binding site and blocked by Akt inhibition. In the neurobehavioral tests, glycine improves the functional recovery of stroke animals pre-injected with MK-801 and strychnine. This study suggests that glycine-induced neuroprotection is mediated in part by the non-ionotropic activity of NMDARs via Akt activation in cerebral ischemia-reperfusion injury.

Isostrychnine synthesis mediated by hypervalent iodine reagent.

PubMed

Jacquemot, Guillaume; Maertens, Gaëtan; Canesi, Sylvain

2015-05-18

Althought there are several reported synthetic routes to strychnine, one of the most widely recognized alkaloids, we report an unexplored route with an oxidative dearomatizing process mediated by hypervalent iodine as the key step. The new syntheses of isostrychnine and strychnine have been achieved from an readily available phenol in nine and ten steps. In addition to the key step, these syntheses involve an aza Michael-ether-enol tandem transformation, two heck type cyclizations, a reductive isomerization, and a double reductive amination in cascade leading to the alkaloid main core. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Syntheses of strychnine, norfluorocurarine, dehydrodesacetylretuline, and valparicine enabled by intramolecular cycloadditions of Zincke aldehydes.

PubMed

Martin, David B C; Nguyen, Lucas Q; Vanderwal, Christopher D

2012-01-06

A full account of the development of the base-mediated intramolecular Diels-Alder cycloadditions of tryptamine-derived Zincke aldehydes is described. This important complexity-generating transformation provides the tetracyclic core of many indole monoterpene alkaloids in only three steps from commercially available starting materials and played a key role in short syntheses of norfluorocurarine (five steps), dehydrodesacetylretuline (six steps), valparicine (seven steps), and strychnine (six steps). Reasonable mechanistic possibilities for this reaction, a surprisingly facile dimerization of the products, and an unexpected cycloreversion to regenerate Zincke aldehydes under specific conditions are also discussed.

Not GABA but glycine mediates segmental, propriospinal, and bulbospinal postsynaptic inhibition in adult mouse spinal forelimb motor neurons.

PubMed

Jiang, Juan; Alstermark, Bror

2015-02-04

The general view is that both glycine (Eccles, 1964) and GABA (Curtis and Felix, 1971) evoke postsynaptic inhibition in spinal motor neurons. In newborn or juvenile animals, there are conflicting results showing postsynaptic inhibition in motor neurons by corelease of GABA and glycine (Jonas et al., 1998) or by glycine alone (Bhumbra et al., 2012). To resolve the relative contributions of GABA and glycine to postsynaptic inhibition, we performed in vivo intracellular recordings from forelimb motor neurons in adult mice. Postsynaptic potentials evoked from segmental, propriospinal, and bulbospinal systems in motor neurons were compared across four different conditions: control, after gabazine, gabazine followed by strychnine, and strychnine alone. No significant differences were observed in the proportion of IPSPs and EPSPs between control and gabazine conditions. In contrast, EPSPs but not IPSPs were recorded after adding strychnine with gabazine or administering strychnine alone, suggesting an exclusive role for glycine in postsynaptic inhibition. To test whether the injected (intraperitoneal) dose of gabazine blocked GABAergic inhibitory transmission, we evoked GABAA receptor-mediated monosynaptic IPSPs in deep cerebellar nuclei neurons by stimulation of Purkinje cell fibers. No monosynaptic IPSPs could be recorded in the presence of gabazine, showing the efficacy of gabazine treatment. Our results demonstrate that, in the intact adult mouse, the postsynaptic inhibitory effects in spinal motor neurons exerted by three different systems, intrasegmental and intersegmental as well as supraspinal, are exclusively glycinergic. These findings emphasize the importance of glycinergic postsynaptic inhibition in motor neurons and challenge the view that GABA also contributes. Copyright © 2015 the authors 0270-6474/15/351991-08$15.00/0.

Regulation of neurosteroid allopregnanolone biosynthesis in the rat spinal cord by glycine and the alkaloidal analogs strychnine and gelsemine.

PubMed

Venard, C; Boujedaini, N; Belon, P; Mensah-Nyagan, A G; Patte-Mensah, C

2008-04-22

The neurosteroid allopregnanolone (3alpha,5alpha-THP) is well characterized as a potentially therapeutic molecule which exerts important neurobiological actions including neuroprotective, antidepressant, anxiolytic, anesthetic and analgesic effects. We have recently observed that neurons and glial cells of the rat spinal cord (SC) contain various key steroidogenic enzymes such as 5alpha-reductase and 3alpha-hydroxysteroid oxido-reductase which are crucial for 3alpha,5alpha-THP biosynthesis. Furthermore, we demonstrated that the rat SC actively produces 3alpha,5alpha-THP. As the key factors regulating neurosteroid production by nerve cells are unknown and because glycine is one of the pivotal inhibitory neurotransmitters in the SC, we investigated glycine effects on 3alpha,5alpha-THP biosynthesis in the rat SC. Glycine markedly stimulated [(3)H]-progesterone conversion into [(3)H]3alpha,5alpha-THP by SC slices. The alkaloid strychnine, well-known as a glycine receptor (Gly-R) antagonist, blocked glycine stimulatory effect on 3alpha,5alpha-THP formation. Gelsemine, another alkaloid containing the same functional groups as strychnine, increased 3alpha,5alpha-THP synthesis. The stimulatory effects of glycine and gelsemine on 3alpha,5alpha-THP production were additive when the two drugs were combined. These results demonstrate that glycine and gelsemine, acting via Gly-R, upregulate 3alpha,5alpha-THP biosynthesis in the SC. The data also revealed a structure-activity relationship of the analogs strychnine and gelsemine on neurosteroidogenesis. Possibilities are opened for glycinergic agents and gelsemine utilization to stimulate selectively 3alpha,5alpha-THP biosynthetic pathways in diseases evoked by a decreased neurosteroidogenic activity of nerve cells.

Actions of 3-[2′-phosphonomethyl[1,1′-biphenyl]-3-yl]alanine (PMBA) on cloned glycine receptors

PubMed Central

Hosie, Alastair M; Akagi, Hiroyuki; Ishida, Michiko; Shinozaki, Haruhiko

1999-01-01

PMBA is a novel antagonist of strychnine-sensitive glycine receptors in the rat spinal cord, however, its mode of action is unknown. The actions of PMBA on rat glycine receptor α1 and α2 homomers in Xenopus oocytes were studied under two-electrode voltage-clamp. Co-application of PMBA and glycine to both α1 and α2 homomers yielded inward currents which decayed to a steady-state. Responses rose slowly to the same steady-state amplitude following a 2 min pre-incubation in PMBA. Strychnine, but not picrotoxinin, showed similar antagonism to PMBA. The potency of PMBA was independent of membrane potential between −100 and 0 mV. When tested against EC50 concentrations of glycine, PMBA was almost equally potent on α1 (IC50, 406±41 nM: Hill coefficient, 1.5±0.2) and α2 (IC50, 539±56 nM; Hill coefficient, 1.4±0.2) homomers. PMBA (1–10 μM) and strychnine (200 nM) reduced the potency of glycine and the amplitude of the maximal agonist response of α1 and α2 homomers. In 10 μM PMBA, two distinct classes of glycine response were observed on α2, only a single class of responses were observed on α1. There are similarities in PMBA and strychnine antagonism, although these compounds are structurally distinct. The possibility that PMBA interacts at two binding sites which differ in α1 and α2 subunits is discussed. PMBA may provide a lead structure for novel antagonists with which to investigate structural differences in glycine receptor at α1 and α2 subunits. PMID:10205013

Synthesis of (nor)tropeine (di)esters and allosteric modulation of glycine receptor binding.

PubMed

Maksay, Gábor; Nemes, Péter; Vincze, Zoltán; Bíró, Timea

2008-02-15

(Hetero)aromatic mono- and diesters of tropine and nortropine were prepared. Modulation of [3H]strychnine binding to glycine receptors of rat spinal cord was examined with a ternary allosteric model. The esters displaced [3H]strychnine binding with nano- or micromolar potencies and strong negative cooperativity. Coplanarity and distance of the ester moieties of diesters affected the binding affinity being nanomolar for isophthaloyl-bistropane and nortropeines. Nortropisetron had the highest affinity (K(A) approximately 10 nM). Two esters displayed negative cooperativity with glycine in displacement, while three esters of low-affinity and nortropisetron exerted positive cooperativity with glycine.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metaxas, Athena E.; Cort, John R.

The highly toxic plant alkaloid strychnine is often isolated in the form of the anion salt of its protonated tertiary amine. Here we characterize the relative influence of different counterions on 1H and 13C chemical shifts in several strychnine salts in D2O, methanol-d4 (CD3OD) and chloroform-d (CDCl3) solvents. In organic solvents, but not in water, substantial variation in chemical shifts of protons near the tertiary amine was observed among different salts. These secondary shifts reveal differences in the way each anion influences electronic structure within the protonated amine. The distributions of secondary shifts allow salts to be easily distinguished frommore » each other as well as from the free base form. The observed effects are much greater in organic solvents than in water. Slight concentration-dependence in chemical shifts of some protons near the amine was observed for two salts in CDCl3, but this effect is small compared to the influence of the counterion. Distinct chemical shifts in different salt forms of the same compound may be useful as chemical forensic signatures for source attribution and sample matching of alkaloids such as strychnine and possibly other organic acid and base salts.« less

Enantioselective total synthesis of (-)-strychnine using the catalytic asymmetric Michael reaction and tandem cyclization.

PubMed

Ohshima, Takashi; Xu, Youjun; Takita, Ryo; Shimizu, Satoshi; Zhong, Dafang; Shibasaki, Masakatsu

2002-12-11

The enantioselective total synthesis of (-)-strychnine was accomplished through the use of the highly practical catalytic asymmetric Michael reaction (0.1 mol % of (R)-ALB, more than kilogram scale, without chromatography, 91% yield and >99% ee) as well as a tandem cyclization that simultaneously constructed B- and D-rings (>77% yield). Moreover, newly developed reaction conditions for thionium ion cyclization, NaBH3CN reduction of the imine moiety in the presence of Lewis acid to prevent ring opening reaction, and chemoselective reduction of the thioether (desulfurization) in the presence of exocyclic olefin were pivotal to complete the synthesis. The described chemistry paves the way for the synthesis of more advanced Strychnos alkaloids.

Involvement of the strychnine-sensitive glycine receptor in the anxiolytic effects of GlyT1 inhibitors on maternal separation-induced ultrasonic vocalization in rat pups.

PubMed

Komatsu, Hiroko; Furuya, Yoshiaki; Sawada, Kohei; Asada, Takashi

2015-01-05

Several studies have shown that glycine transporter 1 (GlyT1) inhibitors have anxiolytic actions. There are two types of glycine receptor: the strychnine-sensitive glycine receptor (GlyA) and the strychnine-insensitive glycine receptor (GlyB); however, which receptor is the main contributor to the anxiolytic actions of GlyT1 inhibitors is yet to be determined. Here, we clarified which glycine receptor is the main contributor to the anxiolytic effects of GlyT1 inhibitors by using maternal separation-induced ultrasonic vocalization (USV) by rat pups as an index of anxiety. We confirmed that administration of the benzodiazepine diazepam or the selective serotonin reuptake inhibitor escitaloplam, which are both clinically proven anxiolytics, or the GlyT1 inhibitor SSR504734 (2-chloro-N-[(S)-phenyl[(2S)-piperidin-2-yl] methyl]-3-trifluoromethyl benzamide), decreases USV in rat pups. In addition, we showed that another GlyT1 inhibitor, ALX5407 ((R)-N-[3-(4'-fluorophenyl)-3(4'-phenylphenoxy)propyl]sarcosine) also decreases USV in rat pups. SSR504734- or ALX5407-induced decreases in USV were dose-dependently reversed by administration of the GlyA antagonist strychnine, whereas the diazepam- or escitalopram-induced decreases in USV were not. Furthermore, GlyT1-induced decreases in USV were not reversed by administration of the GlyB antagonist L-687,414. Together, these results suggest that GlyA activation is the main contributor to the anxiolytic actions of GlyT1 inhibitors and that the anxiolytic actions of diazepam and escitalopram cannot be attributed to GlyA activation. Our findings provide new insights into the importance of the activation of GlyA in the anxiolytic effects of GlyT1 inhibitors. Copyright © 2014 Elsevier B.V. All rights reserved.

Reaction of Donor-Acceptor Cyclobutanes with Indoles: A General Protocol for the Formal Total Synthesis of (±)-Strychnine and the Total Synthesis of (±)-Akuammicine.

PubMed

Feng, Liang-Wen; Ren, Hai; Xiong, Hu; Wang, Pan; Wang, Lijia; Tang, Yong

2017-03-06

A ligand-promoted catalytic [4+2] annulation reaction using indole derivatives and donor-acceptor (D-A) cyclobutanes is reported, thus providing an efficient and atom-economical access to versatile cyclohexa-fused indolines with excellent levels of diastereoselectivity and a broad substrate scope. In the presence of a chiral SaBOX ligand, excellent enantioselectivity was realized with up to 94 % ee. This novel synthetic method is applied as a general protocol for the total synthesis of (±)-akuammicine and the formal total synthesis of (±)-strychnine from the same common-core scaffold. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nonsynaptic glycine release is involved in the early KCC2 expression.

PubMed

Allain, Anne-Emilie; Cazenave, William; Delpy, Alain; Exertier, Prisca; Barthe, Christophe; Meyrand, Pierre; Cattaert, Daniel; Branchereau, Pascal

2016-07-01

The cation-chloride co-transporters are important regulators of the cellular Cl(-) homeostasis. Among them the Na(+) -K(+) -2Cl(-) co-transporter (NKCC1) is responsible for intracellular chloride accumulation in most immature brain structures, whereas the K(+) -Cl(-) co-transporter (KCC2) extrudes chloride from mature neurons, ensuring chloride-mediated inhibitory effects of GABA/glycine. We have shown that both KCC2 and NKCC1 are expressed at early embryonic stages (E11.5) in the ventral spinal cord (SC). The mechanisms by which KCC2 is prematurely expressed are unknown. In this study, we found that chronically blocking glycine receptors (GlyR) by strychnine led to a loss of KCC2 expression, without affecting NKCC1 level. This effect was not dependent on the firing of Na(+) action potentials but was mimicked by a Ca(2+) -dependent PKC blocker. Blocking the vesicular release of neurotransmitters did not impinge on strychnine effect whereas blocking volume-sensitive outwardly rectifying (VSOR) chloride channels reproduced the GlyR blockade, suggesting that KCC2 is controlled by a glycine release from progenitor radial cells in immature ventral spinal networks. Finally, we showed that the strychnine treatment prevented the maturation of rhythmic spontaneous activity. Thereby, the GlyR-activation is a necessary developmental process for the expression of functional spinal motor networks. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 764-779, 2016. © 2015 Wiley Periodicals, Inc.

21 CFR 522.1380 - Methocarbamol.

Code of Federal Regulations, 2014 CFR

2014-04-01

... to 100 mg per pound of body weight for severe conditions (tetanus and strychnine poisoning). The... body weight for severe conditions (tetanus). Additional amounts may be needed to relieve residual...

Strychnine

MedlinePlus

... Cyanogen chloride (CK) Digitalis Case Definition: Digitalis Poisoning Ethylene glycol Fentanyls and other opioids Case Definition: Opioids ( ... Thallium Toxic alcohols Case Definition: Toxic Alcohol Poisoning Ethylene glycol Trichothecene Case Definition: Trichothecene Mycotoxin Poisoning Unidentified ...

Experimental evaluation of rigor mortis. VI. Effect of various causes of death on the evolution of rigor mortis.

PubMed

Krompecher, T; Bergerioux, C; Brandt-Casadevall, C; Gujer, H R

1983-07-01

The evolution of rigor mortis was studied in cases of nitrogen asphyxia, drowning and strangulation, as well as in fatal intoxications due to strychnine, carbon monoxide and curariform drugs, using a modified method of measurement. Our experiments demonstrated that: (1) Strychnine intoxication hastens the onset and passing of rigor mortis. (2) CO intoxication delays the resolution of rigor mortis. (3) The intensity of rigor may vary depending upon the cause of death. (4) If the stage of rigidity is to be used to estimate the time of death, it is necessary: (a) to perform a succession of objective measurements of rigor mortis intensity; and (b) to verify the eventual presence of factors that could play a role in the modification of its development.

Reaction schemes visualized in network form: the syntheses of strychnine as an example.

PubMed

Proudfoot, John R

2013-05-24

Representation of synthesis sequences in a network form provides an effective method for the comparison of multiple reaction schemes and an opportunity to emphasize features such as reaction scale that are often relegated to experimental sections. An example of data formatting that allows construction of network maps in Cytoscape is presented, along with maps that illustrate the comparison of multiple reaction sequences, comparison of scaffold changes within sequences, and consolidation to highlight common key intermediates used across sequences. The 17 different synthetic routes reported for strychnine are used as an example basis set. The reaction maps presented required a significant data extraction and curation, and a standardized tabular format for reporting reaction information, if applied in a consistent way, could allow the automated combination of reaction information across different sources.

Biogenetically inspired approach to the Strychnos alkaloids. Concise syntheses of (+/-)-akuammicine and (+/-)-strychnine.

PubMed

Ito, M; Clark, C W; Mortimore, M; Goh, J B; Martin, S F

2001-08-22

A linear synthesis of the indole alkaloid (+/-)-akuammicine (2) was completed by a novel sequence of reactions requiring only 10 steps from commercially available starting materials. The approach features a tandem vinylogous Mannich addition and an intramolecular hetero Diels-Alder reaction to rapidly assemble the pentacyclic heteroyohimboid derivative 8 from the readily available hydrocarboline 6. Oxidation of the E ring of 8 gave the lactone 9 that was converted into deformylgeissoschizine (11). The subsequent elaboration of 11 into 2 was effected by a biomimetically patterned transformation that involved sequential oxidation and base-induced skeletal reorganization. A variation of these tactics was then applied to the synthesis of the C(18) hydroxylated akuammicine derivative 36. Because 36 had previously been converted into strychnine (1) in four steps, its preparation constitutes a concise, formal synthesis of this complex alkaloid.

Extrasynaptic Glycine Receptors of Rodent Dorsal Raphe Serotonergic Neurons: A Sensitive Target for Ethanol

PubMed Central

Maguire, Edward P; Mitchell, Elizabeth A; Greig, Scott J; Corteen, Nicole; Balfour, David J K; Swinny, Jerome D; Lambert, Jeremy J; Belelli, Delia

2014-01-01

Alcohol abuse is a significant medical and social problem. Several neurotransmitter systems are implicated in ethanol's actions, with certain receptors and ion channels emerging as putative targets. The dorsal raphe (DR) nucleus is associated with the behavioral actions of alcohol, but ethanol actions on these neurons are not well understood. Here, using immunohistochemistry and electrophysiology we characterize DR inhibitory transmission and its sensitivity to ethanol. DR neurons exhibit inhibitory ‘phasic' post-synaptic currents mediated primarily by synaptic GABAA receptors (GABAAR) and, to a lesser extent, by synaptic glycine receptors (GlyR). In addition to such phasic transmission mediated by the vesicular release of neurotransmitter, the activity of certain neurons may be governed by a ‘tonic' conductance resulting from ambient GABA activating extrasynaptic GABAARs. However, for DR neurons extrasynaptic GABAARs exert only a limited influence. By contrast, we report that unusually the GlyR antagonist strychnine reveals a large tonic conductance mediated by extrasynaptic GlyRs, which dominates DR inhibition. In agreement, for DR neurons strychnine increases their input resistance, induces membrane depolarization, and consequently augments their excitability. Importantly, this glycinergic conductance is greatly enhanced in a strychnine-sensitive fashion, by behaviorally relevant ethanol concentrations, by drugs used for the treatment of alcohol withdrawal, and by taurine, an ingredient of certain ‘energy drinks' often imbibed with ethanol. These findings identify extrasynaptic GlyRs as critical regulators of DR excitability and a novel molecular target for ethanol. PMID:24264816

Studies on neuropharmacological profile of ethanol extract of Moringa oleifera leaves in mice.

PubMed

Bakre, Adewale G; Aderibigbe, Adegbuyi O; Ademowo, Olusegun G

2013-10-07

Moringa oleifera (family Moringaceae), commonly called Horseradish or tree of life, is traditionally used for the treatment of epilepsy and neurologic conditions. The objective of this study is to investigate the neurobehavioural and anticonvulsant properties of the ethanol extract from the leaves of Moringa oleifera. Neurobehavioural properties were evaluated using the open field, hole board, Y-maze, elevated plus maze (EPM) and pentobarbitone-induced hypnosis. Pentylenetetrazole (leptazol), picrotoxin and strychnine induced convulsion tests were used to investigate the anti-convulsive actions of Moringa oleifera. The result showed that the extract (250-2000mg/kg) caused a significant dose-dependent decrease in rearing, grooming, head dips and locomotion (P<0.001). It also enhanced learning and memory and increased anxiogenic effect. In addition, the extract (2000mg/kg) protected mice against pentylenetetrazol induced convulsion, but has no effect on picrotoxin and strychnine induced convulsion. The effects of the extract in the various models were comparable to those of the standard drugs used except in Y-maze, EPM and picrotoxin and strychnine induced convulsion. The LD50 obtained for the acute toxicity studied using oral route of administration was >6.4g/kg. The findings from this study suggest that the ethanol extract of Moringa oleifera leaves possesses CNS depressant and anticonvulsant activities possibly mediated through the enhancement of central inhibitory mechanism involving release γ-amino butyric acid (GABA). The results partially justified the traditional use of the extract for the treatment of epilepsy. © 2013 Elsevier Ireland Ltd. All rights reserved.

Crystal structure of human glycine receptor-α3 bound to antagonist strychnine.

PubMed

Huang, Xin; Chen, Hao; Michelsen, Klaus; Schneider, Stephen; Shaffer, Paul L

2015-10-08

Neurotransmitter-gated ion channels of the Cys-loop receptor family are essential mediators of fast neurotransmission throughout the nervous system and are implicated in many neurological disorders. Available X-ray structures of prokaryotic and eukaryotic Cys-loop receptors provide tremendous insights into the binding of agonists, the subsequent opening of the ion channel, and the mechanism of channel activation. Yet the mechanism of inactivation by antagonists remains unknown. Here we present a 3.0 Å X-ray structure of the human glycine receptor-α3 homopentamer in complex with a high affinity, high-specificity antagonist, strychnine. Our structure allows us to explore in detail the molecular recognition of antagonists. Comparisons with previous structures reveal a mechanism for antagonist-induced inactivation of Cys-loop receptors, involving an expansion of the orthosteric binding site in the extracellular domain that is coupled to closure of the ion pore in the transmembrane domain.

Evolution of a short route to strychnine by using the samarium-diiodide-induced cascade cyclization as a key step.

PubMed

Beemelmanns, Christine; Reissig, Hans-Ulrich

2015-06-01

This comprehensive report accounts the development of a highly diastereoselective samarium diiodide-induced cascade reaction of substituted indolyl ketones. The complexity-generating transformation with SmI2 allows the diastereoselective generation of three stereogenic centers including one quaternary center in one step. The obtained tetra- or pentacyclic dihydroindole derivatives are structural motifs of many monoterpene indole alkaloids, and their subsequent transformations gave way to one of the shortest approaches towards strychnine (14 % overall yield in ten steps, or 10 % overall yield in eight steps). During the course of this report we discuss the influence of substituents on the cyclization step, plausible mechanistic scenarios for the SmI2 -induced cascade reaction, diastereoselective reductive amination, and regioselective dehydratization protocols towards the pentacyclic core structure of strychnos alkaloids. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Approaches to the synthesis of (+/-)-strychnine via the cobalt-mediated [2 + 2 + 2] cycloaddition: rapid assembly of a classic framework.

PubMed

Eichberg, M J; Dorta, R L; Grotjahn, D B; Lamottke, K; Schmidt, M; Vollhardt, K P

2001-09-26

Five synthetic approaches to racemic strychnine (1), with the cobalt-mediated [2 + 2 + 2] cycloaddition of alkynes to indoles as the key step, are described. These include the generation and attempted cyclization of macrocycle 8 and the synthesis of dihydrocarbazoles 15, 22, and 26 and their elaboration to pentacyclic structures via a conjugate addition, dipolar cycloaddition, and propellane-to-spirofused skeletal rearrangement, respectively. Finally, the successful total synthesis of 1 is discussed. The development of a short, highly convergent route (14 steps in the longest linear sequence) is highlighted by the cyclization of enynoylindole 40 with acetylene and the formal intramolecular 1,8-conjugate addition of amine 49 to form pentacycle 50. Numerous attempts toward the formation of the piperidine ring of 1 from vinyl iodide 56 were made and its successful formation via palladium-, nickel-, and radical-mediated processes is described.

A novel and general synthetic pathway to strychnos indole alkaloids: total syntheses of (-)-tubifoline, (-)-dehydrotubifoline, and (-)-strychnine using palladium-catalyzed asymmetric allylic substitution.

PubMed

Mori, Miwako; Nakanishi, Masato; Kajishima, Daisuke; Sato, Yoshihiro

2003-08-13

A method of palladium-catalyzed asymmetric allylic substitution for synthesizing 2-substituted cyclohexenylamine derivatives was established. Treatment of a 2-silyloxymethylcyclohexenol derivative with ortho-bromo-N-tosylaniline in the presence of Pd(2)dba(3).CHCl(3) and (S)-BINAPO in THF afforded a cyclohexenylamine derivative with 84% ee in 80% yield. The Heck reaction was carried out to produce an indolenine derivative in good yield. Using this method, we synthesized indolenine derivative 7, which was recrystallized from EtOH to give an optically pure compound. From this compound, tetracyclic ketone 13, which should be a useful intermediate for the synthesis of indole alkaloids, could be synthesized. The total syntheses of (-)-dehydrotubifoline, (-)-tubifoline, and (-)-strychnine were achieved from 13. All ring constructions for the syntheses of these natural products were achieved using a palladium catalyst.

[In vitro absorption mechanism of strychnine and the transport interaction with liquiritin in Caco-2 cell monolayer model].

PubMed

Wang, Jun-jun; Liao, Xiao-huan; Ye, Min; Chen, Yong

2010-09-01

To study the effect of liquiritin (Liq) on the transport of strychnine (Str) in Caco-2 cell monolayer model, the transport parameters of Str, such as apparent permeability coefficient (P app (B-->A) and P app (A-->B)) and cumulative transport amount (TRcum), were determined and comparatively analyzed when Str was used solely and co-used with Liq. The effect of drug concentrations, conveying times, P-glycoprotein (P-gp) inhibitor verapamil and conveying liquor pH values on the transport of Str were also investigated. The results indicated that the absorption of Str in Caco-2 cell monolayer model was well and the passive transference was the main intestinal absorption mechanism of Str in the Caco-2 monolayer model, along with the excretion action mediated by P-gp. Liq enhanced the absorption of Str. Meanwhile, conveying liquor pH value had significant influence on the excretion transport of Str.

Accumbal strychnine-sensitive glycine receptors: an access point for ethanol to the brain reward system.

PubMed

Molander, Anna; Söderpalm, Bo

2005-01-01

Ethanol (EtOH), like other drugs of abuse, increases extracellular dopamine (DA) levels in the nucleus accumbens (nAc) of the brain reward system, an effect that may be of importance for alcohol addiction. How this DA increase is produced is not fully understood, although previous studies from the present laboratories indicate that nicotinic acetylcholine receptors in the ventral tegmental area play an important role in mediating this effect. Furthermore, activation of these receptors may be secondary to some priming effect produced by EtOH in the nAc. We recently demonstrated that strychnine-sensitive glycine receptors (GlyRs) are present in the nAc and that they are involved in regulating extracellular DA levels. Here we examine the tentative role of these accumbal GlyRs in the above-mentioned priming mechanism of EtOH. In vivo microdialysis (coupled to high pressure liquid chromatography with electrochemical detection) and reversed microdialysis, in awake, freely moving adult male Wistar rats. Local perfusion of strychnine decreased accumbal DA levels per se and completely prevented the increase of accumbal DA levels after both local and systemic EtOH administration. Accumbal perfusion of the GlyR agonist glycine instead increased DA levels in a subpopulation of rats and prevented the EtOH-induced increase after local but not systemic EtOH in all animals. The present results suggest that GlyRs in the nAc might constitute targets for EtOH in its mesolimbic DA-activating effect. Gene polymorphism and drug developmental studies that focus on this receptor population and its relation to alcohol dependence are warranted.

Taurine elevates dopamine levels in the rat nucleus accumbens; antagonism by strychnine.

PubMed

Ericson, Mia; Molander, Anna; Stomberg, Rosita; Söderpalm, Bo

2006-06-01

The mesolimbic dopamine (DA) system, projecting from the ventral tegmental area (VTA) to the nucleus accumbens (nAcc), is involved in reward-related behaviours and addictive processes, such as alcoholism and drug addiction. It was recently suggested that strychnine-sensitive glycine receptors (GlyR) in the nAcc regulate both basal and ethanol-induced mesolimbic DA activity via a neuronal loop involving endogenous activation of nicotinic acetylcholine receptors (nAChR) in the VTA. However, as the nAcc appears to contain few glycine-immunoreactive cell bodies or fibres, the question as to what may be the endogenous ligand for GlyRs in this brain region remains open. Here we have investigated whether the amino acid taurine could serve this purpose using in vivo microdialysis in awake, freely moving male Wistar rats. Local perfusion of taurine (1, 10 or 100 mm in the perfusate) increased DA levels in the nAcc. The taurine (10 mm)-induced DA increase was, similarly to that previously observed after ethanol, completely blocked by (i) perfusion of the competitive GlyR antagonist strychnine in the nAcc, (ii) perfusion of the nAChR antagonist mecamylamine (100 microm) in the VTA, and (iii) systemic administration of the acetylcholine-depleting drug vesamicol (0.4 mg/kg, i.p). The present results suggest that taurine may be an endogenous ligand for GlyRs in the nAcc and that the taurine-induced elevation of DA levels in this area, similarly to that observed after local ethanol, is mediated via a neuronal loop involving endogenous activation of nAChRs in the VTA.

Coordination of Fictive Motor Activity in the Larval Zebrafish Is Generated by Non-Segmental Mechanisms

PubMed Central

Wiggin, Timothy D.; Peck, Jack H.; Masino, Mark A.

2014-01-01

The cellular and network basis for most vertebrate locomotor central pattern generators (CPGs) is incompletely characterized, but organizational models based on known CPG architectures have been proposed. Segmental models propose that each spinal segment contains a circuit that controls local coordination and sends longer projections to coordinate activity between segments. Unsegmented/continuous models propose that patterned motor output is driven by gradients of neurons and synapses that do not have segmental boundaries. We tested these ideas in the larval zebrafish, an animal that swims in discrete episodes, each of which is composed of coordinated motor bursts that progress rostrocaudally and alternate from side to side. We perturbed the spinal cord using spinal transections or strychnine application and measured the effect on fictive motor output. Spinal transections eliminated episode structure, and reduced both rostrocaudal and side-to-side coordination. Preparations with fewer intact segments were more severely affected, and preparations consisting of midbody and caudal segments were more severely affected than those consisting of rostral segments. In reduced preparations with the same number of intact spinal segments, side-to-side coordination was more severely disrupted than rostrocaudal coordination. Reducing glycine receptor signaling with strychnine reversibly disrupted both rostrocaudal and side-to-side coordination in spinalized larvae without disrupting episodic structure. Both spinal transection and strychnine decreased the stability of the motor rhythm, but this effect was not causal in reducing coordination. These results are inconsistent with a segmented model of the spinal cord and are better explained by a continuous model in which motor neuron coordination is controlled by segment-spanning microcircuits. PMID:25275377

ETV REPORT: REMOVAL OF CHEMICAL CONTAMINANTS IN DRINKING WATER — PALL/KINETICO PUREFECTA DRINKING WATER TREATMENT SYSTEM

EPA Science Inventory

The Pall/Kinetico Purefecta™ POU drinking water treatment system was tested for removal of aldicarb, benzene, cadmium, carbofuran, cesium, chloroform, dichlorvos, dicrotophos, fenamiphos, mercury, mevinphos, oxamyl, strontium, and strychnine. The Purefecta™ employs several compon...

The mGluR5 antagonist MPEP elevates accumbal dopamine and glycine levels; interaction with strychnine-sensitive glycine receptors.

PubMed

Chau, PeiPei; Söderpalm, Bo; Ericson, Mia

2011-10-01

Studies have indicated that the metabotropic glutamate receptor 5 (mGluR5) antagonist 6-methyl-2-(phenylethynyl)-pyridine (MPEP) decreases ethanol self-administration, and the same receptor type was also suggested to be involved in the mechanism of action of the anti-craving substance acamprosate. Our previous research suggested that glycine receptors (GlyRs) in the nucleus accumbens (nAc) play a major part in mediating the dopamine-elevating properties of ethanol and are highly involved in the ethanol intake-reducing effect of acamprosate. The aim of this study was to examine if modulation of nAc dopamine via mGluR5 antagonism or GlyR agonism is a linked or separated phenomena. The extracellular levels of dopamine as well as of the GlyR ligands, glycine, taurine and β-alanine were measured in the nAc by means of microdialysis after local perfusion of MPEP (100 or 500 µM) with or without pre-treatment with strychnine. MPEP increased dopamine levels, an effect that was blocked by pre-treatment with strychnine. In addition, the higher MPEP concentration increased glycine output, whereas no alterations of taurine or β-alanine were observed. These results indicate a relationship between the glutamatergic and glycinergic transmitter systems in regulating dopamine output, possibly via alteration of extracellular glycine levels. Taken together with our previous data demonstrating the importance of accumbal GlyRs both in ethanol-induced elevation of nAc dopamine and in ethanol consumption, it is plausible that the effects of MPEP treatment, on dopamine output and on ethanol intake, may be mediated via interaction with the same neuronal circuitry that previously has been demonstrated for ethanol, taurine and acamprosate. © 2011 The Authors, Addiction Biology © 2011 Society for the Study of Addiction.

GABAA- and glycine-mediated inhibitory modulation of the cough reflex in the caudal nucleus tractus solitarii of the rabbit.

PubMed

Cinelli, Elenia; Iovino, Ludovica; Bongianni, Fulvia; Pantaleo, Tito; Mutolo, Donatella

2016-09-01

Cough-related sensory inputs from rapidly adapting receptors (RARs) and C fibers are processed by second-order neurons mainly located in the caudal nucleus tractus solitarii (NTS). Both GABAA and glycine receptors have been proven to be involved in the inhibitory control of second-order cells receiving RAR projections. We investigated the role of these receptors within the caudal NTS in the modulation of the cough reflex induced by either mechanical or chemical stimulation of the tracheobronchial tree in pentobarbital sodium-anesthetized, spontaneously breathing rabbits. Bilateral microinjections (30-50 nl) of the receptor antagonists bicuculline and strychnine as well as of the receptor agonists muscimol and glycine were performed. Bicuculline (0.1 mM) and strychnine (1 mM) caused decreases in peak abdominal activity and marked increases in respiratory frequency due to decreases in both inspiratory time (Ti) and expiratory time (Te), without concomitant changes in arterial blood pressure. Noticeably, these microinjections induced potentiation of the cough reflex consisting of increases in the cough number associated with decreases either in cough-related Ti after bicuculline or in both cough-related Ti and Te after strychnine. The effects caused by muscimol (0.1 mM) and glycine (10 mM) were in the opposite direction to those produced by the corresponding antagonists. The results show that both GABAA and glycine receptors within the caudal NTS mediate a potent inhibitory modulation of the pattern of breathing and cough reflex responses. They strongly suggest that disinhibition is one important mechanism underlying cough regulation and possibly provide new hints for novel effective antitussive strategies. Copyright © 2016 the American Physiological Society.

Role of ionotropic GABA, glutamate and glycine receptors in the tonic and reflex control of cardiac vagal outflow in the rat

PubMed Central

2010-01-01

Background Cardiac vagal preganglionic neurons (CVPN) are responsible for the tonic, reflex and respiratory modulation of heart rate (HR). Although CVPN receive GABAergic and glutamatergic inputs, likely involved in respiratory and reflex modulation of HR respectively, little else is known regarding the functions controlled by ionotropic inputs. Activation of g-protein coupled receptors (GPCR) alters these inputs, but the functional consequence is largely unknown. The present study aimed to delineate how ionotropic GABAergic, glycinergic and glutamatergic inputs contribute to the tonic and reflex control of HR and in particular determine which receptor subtypes were involved. Furthermore, we wished to establish how activation of the 5-HT1A GPCR affects tonic and reflex control of HR and what ionotropic interactions this might involve. Results Microinjection of the GABAA antagonist picrotoxin into CVPN decreased HR but did not affect baroreflex bradycardia. The glycine antagonist strychnine did not alter HR or baroreflex bradycardia. Combined microinjection of the NMDA antagonist, MK801, and AMPA antagonist, CNQX, into CVPN evoked a small bradycardia and abolished baroreflex bradycardia. MK801 attenuated whereas CNQX abolished baroreceptor bradycardia. Control intravenous injections of the 5-HT1A agonist 8-OH-DPAT evoked a small bradycardia and potentiated baroreflex bradycardia. These effects were still observed following microinjection of picrotoxin but not strychnine into CVPN. Conclusions We conclude that activation of GABAA receptors set the level of HR whereas AMPA to a greater extent than NMDA receptors elicit baroreflex changes in HR. Furthermore, activation of 5-HT1A receptors evokes bradycardia and enhances baroreflex changes in HR due to interactions with glycinergic neurons involving strychnine receptors. This study provides reference for future studies investigating how diseases alter neurochemical inputs to CVPN. PMID:20939929

Mechanism of Action of Presynaptic Neurotoxins

DTIC Science & Technology

1986-07-01

Green, 1981;. (2) There are no consistent effeects of the toxin on neurotransmftter synthesis , storage, degradation, or uptake (Collingrldge et al...Transport by Nitrendipine fit a Clonal Cell Line. ýL Biol. Chem,. 257, 13189-13192. Van Heyningen W.E. (1963) The Fixation of Tetanus Toxin, Strychnine

Hypothalamic digoxin, hemispheric chemical dominance, and sleep.

PubMed

Kurup, Ravi Kumar; Kurup, Parameswara Achutha

2003-04-01

The isoprenoid path way produces endogenous digoxin, a substance that can regulate neurotransmitter and amino acid transport. Digoxin synthesis and neurotransmitter patterns were assessed in individuals with chronic insomnia. The patterns were compared in those with right hemispheric and left hemispheric dominance. The activity of HMG GoA reductase and serum levels of digoxin, magnesium, tryptophan catabolites, and tyrosine catabolites were measured in individuals with chronic insomnia and in individuals with differing hemispheric dominance. Digoxin synthesis was increased with upregulated tryptophan catabolism (increased levels of serotonin, strychnine, and nicotine), and downregulated tyrosine catabolism (decreased levels of dopamine, noradrenaline, and morphine) in those with chronic insomnia and right hemispheric chemical dominance. Digoxin synthesis was reduced with downregulated tryptophan catabolism (decreased levels of serotonin, strychnine, and nicotine) and upregulated tyrosine catabolism (increased levels of dopamine, noradrenaline, and morphine) in those with normal sleep patterns and left hemispheric chemical dominance. Hypothalamic digoxin plays a central role in the regulation of sleep behavior. Hemispheric chemical dominance in relation to digoxin status is also crucial.

Design and Synthesis of Novel Phenylpiperazine Derivatives as Potential Anticonvulsant Agents.

PubMed

Habib, Monica M W; Abdelfattah, Mohamed A O; Abadi, Ashraf H

2015-12-01

Eighteen new 5-benzylidene-3-(4-arylpiperazin-1-ylmethyl)-2-thioxo-imidazolidin-4-ones were designed as hybrid structures from previously reported anticonvulsant compounds, synthesized and tested for anticonvulsant activity. Initial anticonvulsant screening was performed using the strychnine (2 mg/kg IP) potent generalized-induced seizure and pentylenetetrazole (PTZ) (60 mg/kg IP) acute clonic-induced convulsion screens in mice. All the molecules were found to be effective in at least one seizure model, compounds 10, 13, 15, 17, and 18 were active against both types of seizures induced. Compound 13 turned out to be the most active candidate within the strychnine model, having an average survival time of 6 min close to that of the positive control phenytoin, while compound 8 showed 100% protection from the induced PTZ seizures, resembling the protection of the positive control phenobarbital. Initial SAR studies for anticonvulsant activity are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Role of inhibitory amino acids in control of hypoglossal motor outflow to genioglossus muscle in naturally sleeping rats.

PubMed

Morrison, Janna L; Sood, Sandeep; Liu, Hattie; Park, Eileen; Liu, Xia; Nolan, Philip; Horner, Richard L

2003-11-01

The hypoglossal motor nucleus innervates the genioglossus (GG) muscle of the tongue, a muscle that helps maintain an open airway for effective breathing. Rapid-eye-movement (REM) sleep, however, recruits powerful neural mechanisms that can abolish GG activity even during strong reflex stimulation such as by hypercapnia, effects that can predispose to sleep-related breathing problems in humans. We have developed an animal model to chronically manipulate neurotransmission at the hypoglossal motor nucleus using in vivo microdialysis in freely behaving rats. This study tests the hypothesis that glycine receptor antagonism at the hypoglossal motor nucleus, either alone or in combination with GABAA receptor antagonism, will prevent suppression of GG activity in natural REM sleep during room air and CO2-stimulated breathing. Rats were implanted with electroencephalogram and neck muscle electrodes to record sleep-wake states, and GG and diaphragm electrodes for respiratory muscle recording. Microdialysis probes were implanted into the hypoglossal motor nucleus for perfusion of artificial cerebrospinal fluid (ACSF) and strychnine (glycine receptor antagonist, 0.1 mM) either alone or combined with bicuculline (GABAA antagonist, 0.1 mM) during room air and CO2-stimulated breathing. Compared to ACSF controls, glycine receptor antagonism at the hypoglossal motor nucleus increased respiratory-related GG activity in room air (P = 0.010) but not hypercapnia (P = 0.221). This stimulating effect of strychnine in room air did not depend on the prevailing sleep-wake state (P = 0.625) indicating removal of a non-specific background inhibitory glycinergic tone. Nevertheless, GG activity remained minimal in those REM sleep periods without phasic twitches in GG muscle, with GG suppression from non-REM (NREM) sleep being > 85 % whether ACSF or strychnine was at the hypoglossal motor nucleus or the inspired gas was room air or 7 % CO2. While GG activity was minimal in these REM sleep periods, there was a small but measurable increase in GG activity after strychnine (P < 0.05). GG activity was also minimal, and effectively abolished, in the REM sleep periods without GG twitches with combined glycine and GABAA receptor antagonism at the hypoglossal motor nucleus. We conclude that these data in freely behaving rats confirm that inhibitory glycine and GABAA receptor mechanisms are present at the hypoglossal motor nucleus and are tonically active, but that such inhibitory mechanisms make only a small contribution to the marked suppression of GG activity and reflex responses observed in periods of natural REM sleep.

21 CFR 522.1704 - Sodium pentobarbital injection.

Code of Federal Regulations, 2010 CFR

2010-04-01

... general anesthetic in dogs and cats. Although it may be used as a general surgical anesthetic for horses... local anesthetic. It may also be used in dogs for the symptomatic treatment of strychnine poisoning. (ii) The drug is administered intravenously “to effect”. For general surgical anesthesia, the usual dose is...

21 CFR 522.1704 - Sodium pentobarbital injection.

Code of Federal Regulations, 2011 CFR

2011-04-01

... general anesthetic in dogs and cats. Although it may be used as a general surgical anesthetic for horses... local anesthetic. It may also be used in dogs for the symptomatic treatment of strychnine poisoning. (ii) The drug is administered intravenously “to effect”. For general surgical anesthesia, the usual dose is...

21 CFR 522.1704 - Sodium pentobarbital injection.

Code of Federal Regulations, 2013 CFR

2013-04-01

... general anesthetic in dogs and cats. Although it may be used as a general surgical anesthetic for horses, it is usually given at a lower dose to cause sedation and hypnosis and may be supplemented with a local anesthetic. It may also be used in dogs for the symptomatic treatment of strychnine poisoning. (ii...

ETV REPORT: REMOVAL OF CHEMICAL CONTAMINANTS IN DRINKING WATER — ECOWATER SYSTEMS, INC. ERO-R450E WATER TREATMENT SYSTEM

EPA Science Inventory

The EcoWater Systems ERO-R450E POU drinking water treatment system was tested for removal of aldicarb, benzene, cadmium, carbofuran, cesium, chloroform, dichlorvos, dicrotophos, fenamiphos, mercury, mevinphos, oxamyl, strontium, and strychnine. The ERO-R450E employs a reverse os...

ETV REPORT: REMOVAL OF CHEMICAL CONTAMINANTS IN DRINKING WATER – WATTS PREMIER INC. WP-4V DRINKING WATER TREATMENT SYSTEM

EPA Science Inventory

The Watts Premier WP-4V POU drinking water treatment system was tested for removal of aldicarb, benzene, cadmium, carbofuran, cesium, chloroform, dichlorvos, dicrotophos, fenamiphos, mercury, mevinphos, oxamyl, strontium, and strychnine. The WP-4V employs a reverse osmosis (RO) m...

Discrimination of heterogenous mRNAs encoding strychnine-sensitive glycine receptors in Xenopus oocytes by antisense oligonucleotides.

PubMed Central

Akagi, H; Patton, D E; Miledi, R

1989-01-01

Three synthetic oligodeoxynucleotides complementary to different parts of an RNA encoding a glycine receptor subunit were used to discriminate heterogenous mRNAs coding for glycine receptors in adult and neonatal rat spinal cord. Injection of the three antisense oligonucleotides into Xenopus oocytes specifically inhibited the expression of glycine receptors by adult spinal cord mRNA. In contrast, the antisense oligonucleotides were much less potent in inhibiting the expression of glycine receptors encoded by neonatal spinal cord mRNA. Northern blot analysis revealed that the oligonucleotides hybridized mostly to an adult cord transcript of approximately 10 kilobases in size. This band was also present in neonatal spinal cord mRNA but its density was about one-fourth of the adult cord message. There was no intense band in the low molecular weight position (approximately 2 kilobases), the existence of which was expected from electrophysiological studies with size-fractionated mRNA of neonatal spinal cord. Our results suggest that in the rat spinal cord there are at least three different types of mRNAs encoding functional strychnine-sensitive glycine receptors. Images PMID:2479016

Studies on chemotherapy of parasitic helminths (VI) effects of various neuropharmacological agents on the motility of Dipylidium caninum.

PubMed

Terada, M; Ishii, A I; Kino, H; Sano, M

1982-06-01

Effects of various neuropharmacological agents on the motility of Dipylidium caninum was studied. 5-HT stimulated the motility of D. caninum, while other drugs such as GABA, adrenaline, phenylephrine, isoproterenol, dibenamine, and propranolol showed little effect. The stimulatory action of 5-HT was antagonized by tryptophol. Stibnal caused paralysis which was blocked by the pretreatment with 5-HT. Paralytic effects were caused by eserine, dichlorovos, ACh, carbachol and DMPP, but not by pilocarpine and McN-A-343. d-Tubocurarine, hexamethonium, and atropine all showed little effect on the motility and on the paralytic action of eserine. Though guanidine showed little effect, strychnine remarkably stimulated the motility. The action of strychnine was stimulated by 5-HT but partially inhibited by tryptophol. Morphine and picrate slightly stimulated the motility, but showed little influence on the paralytic action of eserine. These two agents stimulated the paralyzed preparation by tryptophol transiently and sustainedly, respectively. These results on the cholinergic and serotonergic drugs basically showed good agreement with those reported in trematodes such as Schistosoma mansoni and Fasciola hepatica.

Evaluation of the effect of jobelyn(®) on chemoconvulsants-induced seizure in mice.

PubMed

Umukoro, Solomon; Omogbiya, Itivere Adrian; Eduviere, Anthony Taghogho

2013-01-01

Epilepsy is a common central nervous system (CNS) disorder characterized by seizures resulting from episodic neuronal discharges. The incidence of toxicity and refractoriness has compromised the clinical efficacy of the drugs currently used for the treatment of convulsions. Thus, there is a need to search for new medicines from plant origin that are readily available and safer for the control of seizures. Jobelyn(®) (JB) is a unique African polyherbal preparation used by the natives to treat seizures in children. This investigation was carried out to evaluate whether JB has anti-seizure property in mice. The animals received JB (5, 10 and 20 mg/kg, p.o) 30 min before induction of convulsions with intraperitoneal (i.p.) injection of picotoxin (6 mg/kg), strychnine (2 mg/kg) and pentylenetetrazole (85 mg/kg) respectively. Diazepam (2 mg/kg, p.o.) was used as the reference drug. Anti-seizure activities were assessed based on the ability of test drugs to prevent convulsions, death or to delay the onset of seizures in mice. JB (5, 10 and 20 mg/kg, p.o) could only delay the onset of seizures induced by pentylenetetrazole (85 mg/kg, i.p.) in mice. However, it did not did not offer any protection against seizure episodes, as it failed to prevent the animals, from exhibiting tonic-clonic convulsions caused by pentylenetetrazole (85 mg/kg, i.p.), strychnine (2 mg/kg) or picrotoxin (6 mg/kg, i.p.). On the other hand, diazepam (2 mg/kg, i.p.), offered 100% protection against convulsive seizures, induced by pentylenetetrazole (85 mg/kg, i.p.). However, it failed to prevent seizures produced by strychnine (2 mg/kg, i.p.) or picrotoxin (6 mg/kg, i.p.). Our results suggest that JB could not prevent the examined chemoconvulsants-induced convulsions. However, its ability to delay the latency to seizures induced by pentylenetetrazole suggests that JB might be effective in the control of the seizure spread in epileptic brains.

Geographical characteristics influencing the risk of poisoning in pet dogs: Results of a large population-based epidemiological study in Italy.

PubMed

Calzetta, L; Roncada, P; Piras, C; Soggiu, A; Liccardi, G; Mattei, M; Pistocchini, E

2018-05-01

Pets can act as sentinels for human health and thus surveillance of pet dogs has the potential to improve awareness of emerging risks for animal and public health. The aim of this study was to investigate factors associated with the risk of canine poisoning. In a large population-based epidemiological investigation in Italy performed from January 2015 to January 2016 and April 2016 to April 2017, descriptive statistics were acquired and analysed to determine variables associated with poisoning events in pet dogs. Results were validated in a test population and forecast analysis of risk was performed. The cumulative incidence of poisoning events was low (10.2/1000 dogs/year). Anticoagulant rodenticides, organophosphate pesticides, metaldehyde and strychnine were the most frequent causes of intoxications. Territory characteristics significantly modulated both the frequency and the nature of the involved substances. The seashore area was associated with poisoning by rodenticides (odds ratio, OR, 1.81, 95% confidence interval, CI, 1.54-2.13) and metaldehyde (OR 1.61, 95% CI 1.16-2.28). The hill country area was associated with poisoning by organophosphate pesticides (OR 1.73, 95% CI 1.38-2.15), metaldehyde (OR 2.26, 95% CI 1.53-3.25) and strychnine (OR 1.86, 95% CI, 1.34-2.57). The mountain area was associated with strychnine poisoning (OR 3.79, 95% CI 2.84-5.06). The prospective cumulative incidence of poisoning over 10 years was 9.74% (95% CI 9.57-9.91). These results may be useful for predicting the risk of poisoning and for estimating the risk index related to specific toxic compounds in specific territories. This study suggests that poisoning events in dogs may represent a problem of public health with the potential to affect wildlife and human beings. Copyright © 2018 Elsevier Ltd. All rights reserved.

Identification and Characterization of Strychnine-Binding Peptides Using Phage-Display Screening.

PubMed

Zhang, Fang; Wang, Min; Qiu, Zheng; Wang, Xiao-Meng; Xu, Chun-Lei; Zhang, Xia

2017-01-01

In drug development, phage display is a high-throughput method for identifying the specific cellular targets of drugs. However, insoluble small chemicals remain intractable to this technique because of the difficulty of presenting molecules to phages without occupying or destroying the limited functional groups. In the present study, we selected Strychnine (Stry) as a model compounda and sought to develope an alternative in vitro biopanning strategy against insoluble suspension. A phage library displaying random sequences of fifteen peptides was employed to screen for interactions between Stry and its cellular selective binding peptides, which are of great value to have a complete understanding of the mechanism of Stry for its antitumor activity. After four rounds of biopanning, a selection of 100 binding clones was randomly picked and subjected to modified proliferation and diffusion assays to evaluate the binding affinity of the clones. Finally, eleven clones were identified as positive binders. The corresponding peptides were synthesized and detected for their binding activities using surface plasmon resonance imaging (SPRi). Our study provides a feasible scheme for confirming the interaction of chemical compounds and cellular binding peptides. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Behavioral Characterization of Knockin Mice with Mutations M287L and Q266I in the Glycine Receptor α1 Subunit

PubMed Central

Blednov, Yuri A.; Benavidez, Jill M.; Homanics, Gregg E.

2012-01-01

We used behavioral pharmacology to characterize heterozygous knockin mice with mutations (Q266I or M287L) in the α1 subunit of the glycine receptor (GlyR) (J Pharmacol Exp Ther 340:304–316, 2012). These mutations were designed to reduce (M287L) or eliminate (Q266I) ethanol potentiation of GlyR function. We asked which behavioral effects of ethanol would be reduced more in the Q266I mutant than the M287L and found rotarod ataxia to be the behavior that fulfilled this criterion. Compared with controls, the mutant mice also differed in ethanol consumption, ethanol-stimulated startle response, signs of acute physical dependence, and duration of loss of righting response produced by ethanol, butanol, ketamine, pentobarbital, and flurazepam. Some of these behavioral changes were mimicked in wild-type mice by acute injections of low, subconvulsive doses of strychnine. Both mutants showed increased acoustic startle response and increased sensitivity to strychnine seizures. Thus, in addition to reducing ethanol action on the GlyRs, these mutations reduced glycinergic inhibition, which may also alter sensitivity to GABAergic drugs. PMID:22037202

Molecular basis for zinc potentiation at strychnine-sensitive glycine receptors.

PubMed

Miller, Paul S; Da Silva, Helena M A; Smart, Trevor G

2005-11-11

The divalent cation Zn(2+) is a potent potentiator at the strychnine-sensitive glycine receptor (GlyR). This occurs at nanomolar concentrations, which are the predicted endogenous levels of extracellular neuronal Zn(2+). Using structural modeling and functional mutagenesis, we have identified the molecular basis for the elusive Zn(2+) potentiation site on GlyRs and account for the differential sensitivity of GlyR alpha(1) and GlyR alpha(2) to Zn(2+) potentiation. In addition, juxtaposed to this Zn(2+) site, which is located externally on the N-terminal domain of the alpha subunit, another residue was identified in the nearby Cys loop, a region that is critical for receptor gating in all Cys loop ligand-gated ion channels. This residue acted as a key control element in the allosteric transduction pathway for Zn(2+) potentiation, enabling either potentiation or overt inhibition of receptor activation depending upon the moiety resident at this location. Overall, we propose that Zn(2+) binds to a site on the extracellular outer face of the GlyR alpha subunit and exerts its positive allosteric effect via an interaction with the Cys loop to increase the efficacy of glycine receptor gating.

MK-801, but not drugs acting at strychnine-insensitive glycine receptors, attenuate methamphetamine nigrostriatal toxicity.

PubMed

Layer, R T; Bland, L R; Skolnick, P

1993-10-15

Repeated administration of methamphetamine (METH) results in damage to nigrostriatal dopaminergic neurons. Both competitive N-methyl-D-aspartate (NMDA) receptor antagonists and use-dependent cation channel blockers attenuate METH-induced damage. The objectives of the present study were to examine whether comparable reductions in METH-induced damage could be obtained by compounds acting at strychnine-insensitive glycine receptors on the NMDA receptor complex. Four injections of METH (5 mg/kg i.p.) resulted in a approximately 70.9% depletion of striatal dopamine (DA) and approximately 62.7% depletion of dihydroxyphenylacetic acid (DOPAC) content, respectively. A significant protection against METH-induced DA and DOPAC depletion was afforded by the use-dependent channel blocker, MK-801. The competitive glycine antagonist 7-chlorokynurenic acid (7-Cl-KA), the low efficacy glycine partial agonist (+)-3-amino-1-hydroxy-2-pyrrolidone ((+)-HA-966), and the high efficacy partial glycine agonist 1-aminocyclopropane-carboxylic acid (ACPC) were ineffective against METH-induced toxicity despite their abilities to attenuate glutamate-induced neurotoxicity under both in vivo and in vitro conditions. These results indicate that glycinergic ligands do not possess the same broad neuroprotective spectrum as other classes of NMDA antagonists.

Can one gain spectral information plus time by 3D HMBC via back-projection?

PubMed

Findeisen, Matthias; Bermel, Wolfgang; Berger, Stefan

2006-04-01

The 3D HMBC technique is compared with a time saving technique in which the projection-reconstruction (PR) principle is applied. Using strychnine as an example we demonstrate that after recording essentially three planes of the 3D cuboid a comparable result can be obtained, if certain constraints of the data dimensions are obeyed. 2006 John Wiley & Sons, Ltd.

Antipyretic and anticonvulsant activity of n-hexane fraction of Viola betonicifolia.

PubMed

Muhammad, Naveed; Saeed, Muhammad; Khan, Haroon; Raziq, Naila; Halimi, Syed Muhammad Ashhad; Abass, Muzaffer

2013-04-01

To investigate the antipyretic and anticonvulsant activities of n-hexane fraction of Viola betonicifolia (V. betonicifolia). The antipyretic effect was scrutinized using brewer's yeast induced pyrexia and anticonvlsion effect was tested using pentylenetetrazol and strychnine induced convulsion in mice. N-hexane fraction of V. betonicifolia demonstrated highly significant antipyretic activity during various assessment times (1-5 h) when challenged in yeast induced pyrexia test. The effect was in a dose dependent manner with maximum attenuation (82.50%) observed at 300 mg/kg i.p. When tested in pentylenetetrazol induced convulsion test, the 1st stage (Ear and facial twitching) and 2nd stage (Convulsive wave through the body) was 100% protected during 24 h at all the test doses (300, 400 and 500 mg/kg i.p.), while the latency time of remaining stages was significantly increased. The maximum effect was observed by n-hexane fraction of V. betonicifolia at 400 and 500 mg/kg i.p., as the latency time for generalized clonic-tonic seizure (5th stage) was increased up to 25.34 min. However, n-hexane fraction of V. betonicifolia had no protection in strychnine induced convulsion test. In conclusion, phytopharmacological studies provide scientific foundation to the folk uses of the plant in the treatment of pyrexia and neurological disorders.

Antipyretic and anticonvulsant activity of n-hexane fraction of Viola betonicifolia

PubMed Central

Muhammad, Naveed; Saeed, Muhammad; Khan, Haroon; Raziq, Naila; Halimi, Syed Muhammad Ashhad

2013-01-01

Objective To investigate the antipyretic and anticonvulsant activities of n-hexane fraction of Viola betonicifolia (V. betonicifolia). Methods The antipyretic effect was scrutinized using brewer's yeast induced pyrexia and anticonvlsion effect was tested using pentylenetetrazol and strychnine induced convulsion in mice. Results N-hexane fraction of V. betonicifolia demonstrated highly significant antipyretic activity during various assessment times (1-5 h) when challenged in yeast induced pyrexia test. The effect was in a dose dependent manner with maximum attenuation (82.50%) observed at 300 mg/kg i.p. When tested in pentylenetetrazol induced convulsion test, the 1st stage (Ear and facial twitching) and 2nd stage (Convulsive wave through the body) was 100% protected during 24 h at all the test doses (300, 400 and 500 mg/kg i.p.), while the latency time of remaining stages was significantly increased. The maximum effect was observed by n-hexane fraction of V. betonicifolia at 400 and 500 mg/kg i.p., as the latency time for generalized clonic-tonic seizure (5th stage) was increased up to 25.34 min. However, n-hexane fraction of V. betonicifolia had no protection in strychnine induced convulsion test. Conclusions In conclusion, phytopharmacological studies provide scientific foundation to the folk uses of the plant in the treatment of pyrexia and neurological disorders. PMID:23620851

Activation of Strychnine-Sensitive Glycine Receptors by Shilajit on Preoptic Hypothalamic Neurons of Juvenile Mice.

PubMed

Bhattarai, Janardhan Prasad; Cho, Dong Hyu; Han, Seong Kyu

2016-02-29

Shilajit, a mineral pitch, has been used in Ayurveda and Siddha system of medicine to treat many human ailments, and is reported to contain at least 85 minerals in ionic form. This study examined the possible mechanism of Shilajit action on preoptic hypothalamic neurons using juvenile mice. The hypothalamic neurons are the key regulator of many hormonal systems. In voltage clamp mode at a holding potential of -60 mV, and under a high chloride pipette solution, Shilajit induced dose-dependent inward current. Shilajit-induced inward currents were reproducible and persisted in the presence of 0.5 μM tetrodotoxin (TTX) suggesting a postsynaptic action of Shilajit on hypothalamic neurons. The currents induced by Shilajit were almost completely blocked by 2 μM strychnine (Stry), a glycine receptor antagonist. In addition, Shilajit-induced inward currents were partially blocked by bicuculline. Under a gramicidin-perforated patch clamp mode, Shilajit induced membrane depolarization on juvenile neurons. These results show that Shilajit affects hypothalamic neuronal activities by activating the Stry-sensitive glycine receptor with α₂/α₂β subunit. Taken together, these results suggest that Shilajit contains some ingredients with possible glycine mimetic activities and might influence hypothalamic neurophysiology through activation of Stry-sensitive glycine receptor-mediated responses on hypothalamic neurons postsynaptically.

Fast synaptic transmission mediated by α-bungarotoxin-sensitive nicotinic acetylcholine receptors in lamina X neurones of neonatal rat spinal cord

PubMed Central

Bradaïa, A; Trouslard, J

2002-01-01

Using patch clamp recordings on neonatal rat spinal cord slices, we have looked for the presence of α-bungarotoxin-sensitive nicotinic ACh receptors (nAChRs) on sympathetic preganglionic neurones (SPNs) surrounding the central canal of the spinal cord (lamina X) and examined whether they were implicated in a fast cholinergic synaptic transmission. SPNs were identified either by their morphology using biocytin in the recording electrode and/or by antidromic stimulation of the ventral rootlets. The selective α7-containing nAChR (α7*nAChR) agonist choline (10 mm) induced a fast, rapidly desensitizing inward current, which was fully blocked by α-bungarotoxin (α-BgT; 50 nm) and strychnine (1 μm), two antagonists of α7*nAChRs. The I-V relationship of the choline-induced current showed a strong inward-going rectification. Electrically evoked excitatory postsynaptic currents (eEPSCs) could be recorded. At -60 mV, eEPSCs peaked at -26.2 pA and decayed monoexponentially with a mean time constant of 8.5 ms. The current-voltage relationship for eEPSCs exhibited a strong inward rectification and a reversal potential close to 0 mV, compatible with a non-selective cationic current. The appearance of eEPSCs was entirely suppressed by the application of 100 μm ACh or nicotine. Choline (10 mm) and 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP; 100 μm) both reduced the amplitude of eEPSCs, whereas cytisine (100 μm) had no effect. Strychnine (1 μm) and α-BgT (50 nm) both suppressed the eEPSCs. Blocking the P2X purinergic and 5-HT3 receptors had no effect on eEPSCs. DMPP induced four types of current, which differed in their onset and desensitization rate. The most frequently encountered responses were insensitive to the action of strychnine and α-BgT, and were reproduced by ACh and nicotine but not by cytisine. We conclude that SPNs of the lamina X express several classes of nAChRs and in particular α-BgT-sensitive nAChRs. This is the first demonstration in a mammalian spinal cord preparation of a fast cholinergic neurotransmission in which α-BgT-sensitive nicotinic receptors are involved. PMID:12411519

The Neurotrophic Substances and Behavioral Recovery from Brain Damage.

DTIC Science & Technology

1984-11-01

neurotrophic substances that facilitate synthesis may be partially responsible for the com- neuronal regeneration" 12 pensatory effects of the NGF in...1962. Facilitation of simultaneous discrimination learning with strychnine sulphate. Psychopharmacologia 3: 166-172. 21. MEANS, E. D., AND D. K...34 ’- ,P ’% --- SALINE EFFECT 1071 28. SIESJO, B. K. 1981. Cell damage in the brain. A speculative synthesis . J. Cereb. Blood’ Flow Meiab. t: s155-slS5. 29

40 CFR Appendix B to Part 355 - The List of Extremely Hazardous Substances and Their Threshold Planning Quantities

Code of Federal Regulations, 2010 CFR

2010-07-01

... Trifluoride Compound With Methyl Ether (1:1) 1,000 1,000 359-06-8 Fluoroacetyl Chloride b 10 10 371-62-0... Phenylhydrazine Hydrochloride 1,000 1,000/10,000 60-34-4 Methyl Hydrazine 10 500 60-41-3 Strychnine sulfate 10 100... 10 10/10,000 65-30-5 Nicotine sulfate 100 100/10,000 66-81-9 Cycloheximide 100 100/10,000 67-66-3...

40 CFR Appendix B to Part 355 - The List of Extremely Hazardous Substances and Their Threshold Planning Quantities

Code of Federal Regulations, 2011 CFR

2011-07-01

... Trifluoride Compound With Methyl Ether (1:1) 1,000 1,000 359-06-8 Fluoroacetyl Chloride b 10 10 371-62-0... Phenylhydrazine Hydrochloride 1,000 1,000/10,000 60-34-4 Methyl Hydrazine 10 500 60-41-3 Strychnine sulfate 10 100... 10 10/10,000 65-30-5 Nicotine sulfate 100 100/10,000 66-81-9 Cycloheximide 100 100/10,000 67-66-3...

Taurine activates strychnine-sensitive glycine receptors in neurons of the rat inferior colliculus.

PubMed

Xu, Han; Zhou, Ke-Qing; Huang, Yi-Na; Chen, Lin; Xu, Tian-Le

2004-09-24

Taurine (Tau) is one of the most abundant free amino acids in the mammalian central nervous system. Whether the neurotransmission of the central auditory system is regulated or modulated by Tau is not clear. In the present study, we investigated the electrophysiological and pharmacological properties of Tau-activated currents in acutely dissociated neurons of the rat inferior colliculus (IC) using whole cell patch clamp recordings. At a holding potential of -60 mV and under a condition of chloride equilibrium potential near 0 mV, Tau activated an inward current and its half-maximal activation concentration was equal to 0.37 mM. The measured reversal potential of Tau-activated currents was close to theoretical chloride equilibrium potential. The currents evoked by Tau at both low (1 mM) and high (10 mM) concentrations were almost completely inhibited by strychnine, a glycine receptor antagonist. The Tau-activated current, however, was not affected by bicuculline, a GABA(A) receptor antagonist. Tau at increased concentrations progressively reduced the current response to subsequent glycine application. At saturated concentrations, Tau-activated current and glycine-activated current were mutually cross-desensitized by each other. These findings indicate that Tau activates glycine receptors in neurons of the rat IC and thus may have a functional role in regulating or modulating the neurotransmission of the central auditory system in mammals.

Psychopharmacological properties of saponins from Randia nilotica stem bark.

PubMed

Danjuma, N M; Chindo, B A; Abdu-Aguye, I; Anuka, J A; Hussaini, I M

2014-01-01

Decoctions of Randia nilotica Stapf. (Rubiaceae) have been used in the Nigerian traditional medicine for the management of epilepsy, anxiety, depression and psychosis for many years and their efficacies are widely acclaimed among the rural communities of Northern Nigeria. The aim of this study is to establish whether the saponins present in R. nilotica are responsible for its acclaimed beneficial effects in Nigerian traditional medicine. The behavioural properties of the saponin-rich fraction (SFRN) of R. nilotica stem bark were studied on hole-board, diazepam-induced sleep, rota-rod and beam-walking in mice. The anticonvulsant properties of SFRN were also examined on maximal electroshock, pentylenetetrazole- and strychnine-induced seizures in mice. The intraperitoneal LD₅₀ of SFRN in mice and rats were estimated to be 11.1 and 70.7 mg/kg, respectively. SFRN significantly prolonged the duration of diazepam-induced sleep; diminished head dip counts in the hole-board test and protected mice against maximal electroshock seizures. SFRN failed to protect mice against pentylenetetrazole- and strychnine-induced seizures; and had no effect on motor coordination on the rota-rod treadmill at the doses tested. SFRN significantly decreased the number of foot slips in the beam-walking assay in mice with no effect on time to reach the goal box. This study provides evidence of the psychopharmacological effects of SFRN, thus supporting further development of the psychoactive components as remedies for epilepsy.

Relativistic force field: parametric computations of proton-proton coupling constants in (1)H NMR spectra.

PubMed

Kutateladze, Andrei G; Mukhina, Olga A

2014-09-05

Spin-spin coupling constants in (1)H NMR carry a wealth of structural information and offer a powerful tool for deciphering molecular structures. However, accurate ab initio or DFT calculations of spin-spin coupling constants have been very challenging and expensive. Scaling of (easy) Fermi contacts, fc, especially in the context of recent findings by Bally and Rablen (Bally, T.; Rablen, P. R. J. Org. Chem. 2011, 76, 4818), offers a framework for achieving practical evaluation of spin-spin coupling constants. We report a faster and more precise parametrization approach utilizing a new basis set for hydrogen atoms optimized in conjunction with (i) inexpensive B3LYP/6-31G(d) molecular geometries, (ii) inexpensive 4-31G basis set for carbon atoms in fc calculations, and (iii) individual parametrization for different atom types/hybridizations, not unlike a force field in molecular mechanics, but designed for the fc's. With the training set of 608 experimental constants we achieved rmsd <0.19 Hz. The methodology performs very well as we illustrate with a set of complex organic natural products, including strychnine (rmsd 0.19 Hz), morphine (rmsd 0.24 Hz), etc. This precision is achieved with much shorter computational times: accurate spin-spin coupling constants for the two conformers of strychnine were computed in parallel on two 16-core nodes of a Linux cluster within 10 min.

Potential primary and secondary hazards of avicides

USGS Publications Warehouse

Schafer, E.W.; Clark, Dell O.

1984-01-01

There are six chemicals or groups of chemicals that are currently registered as avicides that can be used in some or all of the U.S. Most of these chemicals, because of their diverse chemical composition and innate toxicological effects, present somewhat different primary and secondary hazards to avian and mammalian predators and scavengers. Of the chemicals reviewed, all appear to present some degree of primary hazard to non-target birds and mammals; however, PA-14, the Starlicide family of chemicals and fenthion appear to be the least hazardous when used according to use directions. 4-Aminopyridine, endrin and strychnine, because of their high acute toxicity and lack of selectivity, must be considered potentially more hazardous. With respect to secondary hazards, the ranking of chemicals changes considerably and only PA-14 appears to present a negligible hazard. The Starlicide family of chemicals presents negligible hazards to most animal species under currently registered uses, but may be potentially hazardous to cats and owls under specific use conditions. Two chemicals, 4-aminopyridine and strychnine, are potentially more hazardous to predatory and scavenger animals due to their highly toxic nature and rapid lethal effects in target species, leaving unassimilated chemical in the gastrointestinal tract. The remaining chemicals, endrin and fenthion, have been shown to possess the potential for more significant secondary poisoning; however, because of restrictive uses, most of the potential hazards have been avoided in operational use.

β-Alanine and taurine as endogenous agonists at glycine receptors in rat hippocampus in vitro

PubMed Central

Mori, Masahiro; Gähwiler, Beat H; Gerber, Urs

2002-01-01

Electrophysiological and pharmacological properties of glycine receptors were characterized in hippocampal organotypic slice cultures. In the presence of ionotropic glutamate and GABAB receptor antagonists, pressure-application of glycine onto CA3 pyramidal cells induced a current associated with increased chloride conductance, which was inhibited by strychnine. Similar chloride currents could also be induced with β-alanine or taurine. Whole-cell glycine responses were significantly greater in CA3 pyramidal cells than in CA1 pyramidal cells and dentate granule cells, while responses to GABA were similar among these three cell types. Although these results demonstrate the presence of functional glycine receptors in the hippocampus, no evidence for their activation during synaptic stimulation was found. Gabazine, a selective GABAA receptor antagonist, totally blocked evoked IPSCs in CA3 pyramidal cells. Glycine receptor activation is not dependent on transporter-controlled levels of extracellular glycine, as no chloride current was observed in response to sarcosine, an inhibitor of glycine transporters. In contrast, application of guanidinoethanesulfonic acid, an uptake inhibitor of β-alanine and taurine, induced strychnine-sensitive chloride current in the presence of gabazine. These data indicate that modulation of transporters for the endogenous amino acids, β-alanine and taurine, can regulate tonic activation of glycine receptors, which may function in maintenance of inhibitory tone in the hippocampus. PMID:11850512

Mechanisms underlying recurrent inhibition in the sacral parasympathetic outflow to the urinary bladder.

PubMed Central

de Groat, W C

1976-01-01

1. In cats with the sacral dorsal roots cut on one side electrical stimulation (15-40 c/s) of the central end of the transected ipsilateral pelvic nerve depressed spontaneous bladder contractions. The depression was abolished by transecting the ipsilateral sacral ventral roots. 2. Electrical stimulation of acutely or chronically transected ('deafferented') sacral ventral roots depressed spontaneous bladder contractions and the firing of sacral parasympathetic preganglionic neurones innervating the bladder. The depression of neuronal firing occurred ipsilateral and contralateral to the point of stimulation, but only occurred with stimulation of sacral roots containing preganglionic axons and only with stimulation of sacral roots containing preganglionic axons and only at intensities of stimulation (0-7-4V) above the threshold for activation of these axons. 3. The inhibitory responses were not abolished by strychnine administered by micro-electrophoresis to preganglionic neurones, but were blocked by the intravenous administration of strychnine. 4. The firing of preganglionic neurones elicited by micro-electrophoretic administration of an excitant amino acid (DL-homocysteic acid) was not depressed by stimulation of the ventral roots. 5. It is concluded that the inhibition of the sacral outflow to the bladder by stimulation of sacral ventral roots is related to antidromic activation of vesical preganglionic axons. Collaterals of these axons must excite inhibitory interneurones which in turn depress transmission at a site on the micturition reflex pathway prior to the preganglionic neurones. PMID:950603

Three-dimensional autoradiographic localization of quench-corrected glycine receptor specific activity in the mouse brain using sup 3 H-strychnine as the ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, W.F.; O'Gorman, S.; Roe, A.W.

1990-03-01

The autoradiographic analysis of neurotransmitter receptor distribution is a powerful technique that provides extensive information on the localization of neurotransmitter systems. Computer methodologies are described for the analysis of autoradiographic material which include quench correction, 3-dimensional display, and quantification based on anatomical boundaries determined from the tissue sections. These methodologies are applied to the problem of the distribution of glycine receptors measured by 3H-strychnine binding in the mouse CNS. The most distinctive feature of this distribution is its marked caudorostral gradient. The highest densities of binding sites within this gradient were seen in somatic motor and sensory areas; high densitiesmore » of binding were seen in branchial efferent and special sensory areas. Moderate levels were seen in nuclei related to visceral function. Densities within the reticular formation paralleled the overall gradient with high to moderate levels of binding. The colliculi had low and the diencephalon had very low levels of binding. No binding was seen in the cerebellum or the telencephalon with the exception of the amygdala, which had very low levels of specific binding. This distribution of glycine receptors correlates well with the known functional distribution of glycine synaptic function. These data are illustrated in 3 dimensions and discussed in terms of the significance of the analysis techniques on this type of data as well as the functional significance of the distribution of glycine receptors.« less

Frequency-dependent glycinergic inhibition modulates plasticity in hippocampus.

PubMed

Keck, Tara; Lillis, Kyle P; Zhou, Yu-Dong; White, John A

2008-07-16

Previous studies have demonstrated the presence of functional glycine receptors (GlyRs) in hippocampus. In this work, we examine the baseline activity and activity-dependent modulation of GlyRs in region CA1. We find that strychnine-sensitive GlyRs are open in the resting CA1 pyramidal cell, creating a state of tonic inhibition that "shunts" the magnitude of EPSPs evoked by electrical stimulation of the Schaffer collateral inputs. This GlyR-mediated shunting conductance is independent of the presynaptic stimulation rate; however, pairs of presynaptic and postsynaptic action potentials, repeated at frequencies above 5 Hz, reduce the GlyR-mediated conductance and increase peak EPSP magnitudes to levels at least 20% larger than those seen with presynaptic stimulation alone. We refer to this phenomenon as rate-dependent efficacy (RDE). Exogenous GlyR agonists (glycine, taurine) block RDE by preventing the closure of postsynaptic GlyRs. The GlyR antagonist strychnine blocks postsynaptic GlyRs under all conditions, occluding RDE. During RDE, GlyRs are less responsive to local glycine application, suggesting that a reduction in the number or sensitivity of membrane-inserted GlyRs underlies RDE. By extending the RDE induction protocol to include 500 paired presynaptic and postsynaptic spikes, we can induce long-term synaptic depression (LTD). Manipulations that lead to reduced functionality of GlyRs, either pharmacologically or through RDE, also lead to increased LTD. This result suggests that RDE contributes to long-term synaptic plasticity in the hippocampus.

Action of cholinergic poisons on the central nervous system and effectiveness of potential antidotes. Annual report 1 Jul 81-30 Jun 82

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samson, F.; Nelson, S.

The research aim was to determine the effects of soman, related organophosphate toxins and potential antidotes on brain regional functions in rats: The (/sup 14/C)-2-deoxyglucose procedure (2-DG) was used for mapping brain regional glucose use. Quantitative autoradiography was used for muscarinic and nicotinic cholinergic receptors. The 2-DG procedure gives a quantitative measure of glucose utilization in brain regions and is in index of the 'functional activity' in brain regions and systems. Values were determined in controls, rats with soman induced seizures, seizures induced by convulsants (DFP, strychnine, picrotoxin, pentylenetetrazol, penicillin) and soman pretreated with TAB. Brain regional cholinergic receptor mapsmore » were prepared and some regional muscarinic and nicotinic receptor densities have been quantified. Soman (112 micrograms/kg i.m.) causes strong, continuous seizures and a dramatic (2-6 fold) increase in the rate of glucose use in 10 major brain regions. Most intense increases were in septum, substants nigra reticularis and outer layer of hippcampal dendata gyrus. The overt seizures of rats induced by convulsants DFP, strychnine, picrotoxin, pentylenetetrazol and penicillin (in hippocampus) were strikingly different from that of rats with soman seizures. High doses (2X LD50) of soman in rats protected with TAB caused a 50% depression of glucose use in most brain regions. The effects of repeated soman exposure on muscarinic and nicotinic receptors are under study.« less

Glycine inhibits startle-mediating neurons in the caudal pontine reticular formation but is not involved in synaptic depression underlying short-term habituation of startle.

PubMed

Geis, Hans-Ruediger; Schmid, Susanne

2011-10-01

The mammalian startle response is controlled by glycine inhibition in the spinal cord. Evidence for additional glycine inhibition on the level of the brainstem, namely in the caudal pontine reticular nucleus (PnC), is controversial. Startle mediating PnC neurons receive fast input from sensory pathways and project to cranial and spinal motoneurons. Synaptic depression in the sensory synapses in the PnC has been indicated as underlying mechanism of short-term habituation of startle. We here performed patch-clamp recordings of PnC giant neurons in rat brain slices to test the hypothesis that the activation of glycine receptors inhibits PnC neurons and that this inhibition is involved in synaptic depression in the PnC. Glycine strongly inhibited PnC neuron activity and synaptic signalling, indicating that functional glycine receptors mediate a powerful inhibition of PnC neurons over a wide range of glycine concentrations. Strychnine reversed all glycine effects, but had no effect on PnC neurons itself. Thus, we found no evidence for a tonic glycine inhibition or for glycine activation within the primary startle pathway indicating that baseline startle reactions are unlikely to be controlled by glycine in the PnC. Most importantly, synaptic depression underlying short-term habituation was not affected by glycine or strychnine. Copyright © 2011 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Inhibitory control of plateau properties in dorsal horn neurones in the turtle spinal cord in vitro

PubMed Central

Russo, Raúl E; Nagy, Frédéric; Hounsgaard, Jørn

1998-01-01

The role of inhibition in control of plateau-generating neurones in the dorsal horn was studied in an in vitro preparation of the spinal cord of the turtle. Ionotropic and metabotropic inhibition was found to condition the expression of plateau potentials. Blockade of γ-aminobutyric acid (GABAA) and glycine receptors by their selective antagonists bicuculline (10-50 μM) and strychnine (5-20 μM) enhanced the excitatory response to stimulation of the dorsal root and facilitated the expression of plateau potentials. Bicuculline and strychnine also facilitated the generation of plateau potentials in response to depolarizing current pulses, suggesting the presence of tonic ionotropic inhibitory mechanisms in turtle spinal cord slices. Activation of GABAB receptors also inhibited plateau-generating neurones. The selective agonist baclofen (5-50 μM) inhibited wind-up of the response to repeated depolarizations induced synaptically or by intracellular current pulses. Baclofen reduced afferent synaptic input. This effect was not affected by bicuculline or strychnine and was blocked by the selective GABAB receptor antagonist 2-hydroxysaclofen (2-OH-saclofen, 100-400 μM). Postsynaptically, baclofen inhibited plateau properties. Activation of GABAB receptors produced a hyperpolarization (7.0 ± 0.5 mV, mean ± s.e.m., n= 29) with an associated decrease in input resistance (22.7 ± 3.1 %, n= 24). These effects were blocked by extracellular Ba2+ (1-2 mM). When the baclofen-induced hyperpolarization and shunt were compensated for by adjusting the bias current and the strength of the stimulus, baclofen still inhibited generation of plateau potentials. Wind-up and after-discharges were also inhibited by baclofen. These effects remained in the presence of tetrodotoxin (1 μM) and were antagonized by 2-OH-saclofen. The inhibition of plateau properties was observed even when the baclofen-induced hyperpolarization and shunt were blocked by Ba2+ and when potassium channels were blocked by Ba2+ (3 mM), tetraethylammonium (TEA, 15 mM) and apamin (0.25-0.5 μM). The baclofen-sensitive component of the plateau potential was reduced by nifedipine (10 μM), suggesting a modulation of postsynaptic L-type Ca2+ channels. We suggest that inhibitory regulation of plateau properties plays a role in somatosensory processing in the dorsal horn. The inhibitory control of wind-up and after-discharges may be particularly significant in physiological and therapeutic control of central sensitization to pain. PMID:9503338

The preservation of substance p by lysergic acid diethylamide

PubMed Central

Krivoy, W. A.

1957-01-01

Lysergic acid diethylamide (LSD) potentiated the response of guinea-pig ileum to substance P but not to histamine. It also inhibited the disappearance of substance P when incubated with guinea-pig brain extract but not when incubated with chymotrypsin. Eserine, morphine, mescaline, chlorpromazine, ergometrine, strychnine and 2 bromo-LSD did not have this effect. Oxytocin was not destroyed by brain extract. The inhibition of the destruction of substance P by LSD could be antagonized by 2 bromo-LSD. This effect of LSD may have some relation to its pharmacological actions. PMID:13460245

The preservation of substance P by lysergic acid diethylamide.

PubMed

KRIVOY, W A

1957-09-01

Lysergic acid diethylamide (LSD) potentiated the response of guinea-pig ileum to substance P but not to histamine. It also inhibited the disappearance of substance P when incubated with guinea-pig brain extract but not when incubated with chymotrypsin. Eserine, morphine, mescaline, chlorpromazine, ergometrine, strychnine and 2 bromo-LSD did not have this effect. Oxytocin was not destroyed by brain extract. The inhibition of the destruction of substance P by LSD could be antagonized by 2 bromo-LSD. This effect of LSD may have some relation to its pharmacological actions.

Spinal mechanism of micturition reflex inhibition by naftopidil in rats.

PubMed

Sugaya, Kimio; Nishijima, Saori; Kadekawa, Katsumi; Ashitomi, Katsuhiro; Ueda, Tomoyuki; Yamamoto, Hideyuki

2014-10-29

We investigated the spinal mechanism through which naftopidil inhibits the micturition reflex by comparing the effects of noradrenaline and naftopidil in rats. The following were investigated: the influence of oral naftopidil on plasma monoamine and amino acid levels, the distribution of oral 14C-naftopidil, the effects of intravenous (IV) or intrathecal (IT) injection of noradrenaline or naftopidil on isovolumetric bladder contractions, amino acid levels in the lumbosacral spinal cord after IT noradrenaline or naftopidil, and the effects of IT naftopidil and strychnine and/or bicuculline on isovolumetric bladder contractions. Oral naftopidil decreased the plasma adrenaline level, while it increased the serotonin and glycine levels. After oral administration, 14C-naftopidil was detected in the spinal cord and cerebrum, as well as in plasma and the prostate gland. When the bladder volume was below the threshold for isovolumetric reflex contractions, IV (0.1mg) or IT (0.1μg) noradrenaline evoked bladder contractions, but IV (1mg) or IT (0.01-1μg) naftopidil did not. When the bladder volume was above the threshold for isovolumetric reflex contractions, IV or IT noradrenaline transiently abolished bladder contractions. IT noradrenaline decreased the levels of glycine and gamma-aminobutyric acid (GABA) in the lumbosacral cord, while IT naftopidil increased the GABA level. IT strychnine and/or bicuculline blocked the inhibitory effect of IT naftopidil on bladder contractions. Naftopidil inhibits the micturition reflex by blocking α1 receptors, as well as by the activation of serotonergic, glycinergic, and GABAergic neurons in the central nervous system. Copyright © 2014 Elsevier Inc. All rights reserved.

Developmental regulation of inhibitory synaptic currents in the dorsal motor nucleus of the vagus in the rat

PubMed Central

Anselmi, Laura; Travagli, R. Alberto

2016-01-01

Prior immunohistochemical studies have demonstrated that at early postnatal time points, central vagal neurons receive both glycinergic and GABAergic inhibitory inputs. Functional studies have demonstrated, however, that adult vagal efferent motoneurons receive only inhibitory GABAergic synaptic inputs, suggesting loss of glycinergic inhibitory neurotransmission during postnatal development. The purpose of the present study was to test the hypothesis that the loss of glycinergic inhibitory synapses occurs in the immediate postnatal period. Whole cell patch-clamp recordings were made from dorsal motor nucleus of the vagus (DMV) neurons from postnatal days 1–30, and the effects of the GABAA receptor antagonist bicuculline (1–10 μM) and the glycine receptor antagonist strychnine (1 μM) on miniature inhibitory postsynaptic current (mIPSC) properties were examined. While the baseline frequency of mIPSCs was not altered by maturation, perfusion with bicuculline either abolished mIPSCs altogether or decreased mIPSC frequency and decay constant in the majority of neurons at all time points. In contrast, while strychnine had no effect on mIPSC frequency, its actions to increase current decay time declined during postnatal maturation. These data suggest that in early postnatal development, DMV neurons receive both GABAergic and glycinergic synaptic inputs. Glycinergic neurotransmission appears to decline by the second postnatal week, and adult neurons receive principally GABAergic inhibitory inputs. Disruption of this developmental switch from GABA-glycine to purely GABAergic transmission in response to early life events may, therefore, lead to adverse consequences in vagal efferent control of visceral functions. PMID:27440241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grachev, S.A.; Chakchir, B.A.; Ryabykh, L.D.

The feasibility of radiation sterilization was studied on ephedrine hydrochloride, atropine sulfate, scopolamine hydrobromide, strychnine nitrate, morphine hydrochloride, codeine phosphate, proserine, cysteamine hydrochloride, and unithiol in form of injectable solutions and as powders. It was shown that the sterilizing dose of radioactivity results in a breakdown of the solutions as shown by changes in the pH, color, and loss of biological activity. Alkaloid powders exhibited no changes after radiation sterilization. Deaerated solutions were also stable to the radiation but such solutions could not be prepared easily under industrial conditions. Temperature had no effect on the stability of test samples exceptmore » for very low temperatures. (JPRS)« less

An analytical strategy to investigate Semen Strychni nephrotoxicity based on simultaneous HILIC-ESI-MS/MS detection of Semen Strychni alkaloids, tyrosine and tyramine in HEK 293t cell lysates.

PubMed

Gu, Liqiang; Hou, Pengyi; Zhang, Ruowen; Liu, Ziying; Bi, Kaishun; Chen, Xiaohui

2016-10-15

A Previous metabolomics study has demonstrated that tyrosine metabolism might be disrupted by treating with Semen Strychni on the cell nephrotoxicity model. To investigate the relationship between Semen Strychni alkaloids (SAs) and endogenous tyrosine, tyramine under the nephrotoxicity condition, an HILIC-ESI-MS/MS based analytical strategy was applied in this study. Based on the established Semen Strychni nephrotoxicity cell model, strychnine and brucine were identified and screened as the main SAs by an HPLC-Q Exactive hybrid quadrupole Orbitrap mass system. Then, a sensitive HILIC-ESI-MS/MS method was developed to simultaneously monitor strychnine, brucine, tyrosine and tyramine in cell lysate. The analytes were separated by a Shiseido CAPCELL CORE PC (150mm×2.1mm, 2.7μm) HILIC column in an acetonitrile/0.1% formic acid gradient system. All the calibration curves were linear with regression coefficients above 0.9924. The absolute recoveries were more than 80.5% and the matrix effects were between 91.6%-107.0%. With the developed method, analytes were successfully determined in cell lysates. Decreased levels of tyrosine and tyramine were observed only in combination with increased levels of SAs, indicating that the disturbance of tyrosine metabolism might be induced by the accumulation of SAs in kidney cell after exposure of Semen Strychni. The HILIC-ESI-MS/MS based analytical strategy is a useful tool to reveal the relationships between the toxic herb components and the endogenous metabolite profiling in the toxicity investigation of herb medicines. Copyright © 2016 Elsevier B.V. All rights reserved.

Dynamic detection of non-protein-bound strychnine and brucine in rabbit muscle and synovial fluid after topical application of total Strychnos alkaloid patches.

PubMed

Tang, Huaibo; Yan, Miao; Li, Huande; Xun, Tianrong; Deng, Yang; Zhao, Yeye; Deng, Long

2014-04-01

Semen Strychni, a known toxic drug in Chinese pharmacopoeia, is notable for its therapeutic effects on local muscle and joint pain. However, oral administration can be risky. Topically administered drugs accumulate in the topical muscles and knee joints without any major increase in plasma levels; only non-protein-bound drugs in the biological fluids of target tissues are effective for therapeutic effects. A sensitive and rapid ultra performance liquid chromatography - mass spectrometry (UPLC-MS) method coupled with a microdialysis technique was developed to determine the non-protein-bound strychnine (Str) and brucine (Bru) in rabbit muscle and synovial fluid microdialysate. The UPLC separation was carried out using a 1.7μm BEH C18 column (50 mm × 2.1 mm) with a mobile phase consisting of methanol: water (29.5:70.5, v/v) with 0.1% formic acid and 20 mM ammonium acetate in water. The method was validated at concentrations ranging from 0.58 ng/ml to 467.20 ng/ml for Str and from 0.42 ng/ml to 422.40 ng/ml for Bru. Intra-day and inter-day accuracy ranged from 99.1% to 103.2% for Str and from 95.8% to 108.8% for Bru with intra-day and inter-day precision within 9.7%. The proposed method was successfully applied to determine non-protein-bound Str and Bru, and the analysates concentration remained stable in rabbit muscle and synovial fluid after topical application of total Strychnos alkaloid patches, which indicated that total Strychnos alkaloid patches could substitute for the traditional oral administration of Semen Strychni. Copyright © 2013 John Wiley & Sons, Ltd.

Glycine Transporter 1 is a Target for the Treatment of Epilepsy

PubMed Central

Shen, Hai-Ying; van Vliet, Erwin; Bright, Kerry-Ann; Hanthorn, Marissa; Lytle, Nikki; Gorter, Jan; Aronica, Eleonora; Boison, Detlev

2015-01-01

Glycine is the major inhibitory neurotransmitter in brainstem and spinal cord, whereas in hippocampus glycine exerts dual modulatory roles on strychnine-sensitive glycine receptors and on the strychnine-insensitive glycineB site of the N-methyl-D-aspartate receptor (NMDAR). In hippocampus, the synaptic availability of glycine is largely under control of glycine transporter 1 (GlyT1). Since epilepsy is a disorder of disrupted network homeostasis affecting the equilibrium of various neurotransmitters and neuromodulators, we hypothesized that changes in hippocampal GlyT1 expression and resulting disruption of glycine homeostasis might be implicated in the pathophysiology of epilepsy. Using two different rodent models of temporal lobe epilepsy (TLE) – the intrahippocampal kainic acid model of TLE in mice, and the rat model of tetanic stimulation-induced TLE – we first demonstrated robust overexpression of GlyT1 in the hippocampal formation, suggesting dysfunctional glycine signaling in epilepsy. Overexpression of GlyT1 in the hippocampal formation was corroborated in human TLE samples by quantitative real time PCR. In support of a role of dysfunctional glycine signaling in the pathophysiology of epilepsy, both the genetic deletion of GlyT1 in hippocampus and the GlyT1 inhibitor LY2365109 increased seizure thresholds in mice. Importantly, chronic seizures in the mouse model of TLE were robustly suppressed by systemic administration of the GlyT1 inhibitor LY2365109. We conclude that GlyT1 overexpression in the epileptic brain constitutes a new target for therapeutic intervention, and that GlyT1 inhibitors constitute a new class of antiictogenic drugs. These findings are of translational value since GlyT1 inhibitors are already in clinical development to treat cognitive symptoms in schizophrenia. PMID:26302655

Strychnos nux-vomica extract and its ultra-high dilution reduce voluntary ethanol intake in rats.

PubMed

Sukul, N C; Ghosh, S; Sinhababu, S P; Sukul, A

2001-04-01

To see whether Strychnos nux-vomica extract (mother tincture [MT]), its potency Nux 30c, and its principal alkaloid, strychnine, could reduce voluntary ethanol intake in rats. To analyze the solution structure of Nux MT, Nux 30c, 90% ethanol, and ethanol 30c by means of electronic (ES) and nuclear nuclear magnetic resonance (NMR) spectra. Potentially alcoholic rats were first given 20% ethanol and then kept on a two-choice bottle, one with 20% ethanol and another with tap water. These rats were given the following oral treatments for 15 days: group 1, control; group 2, strychnine at 0.36 mg/kg per day; group 3, ethanolic extract of S. nux-vomica seeds (Nux MT) at 3.6 mg/kg per day; and group 4, Nux 30c at 0.05 mL/d per rat. Nux 30c was prepared by successive dilution of Nux MT and 90% ethanol (1:100) and sonication at 20 kHz for 30 seconds in 30 steps. Both Nux MT and Nux 30c significantly reduced ethanol intake and increased water intake in rats. ES of two dilutions of Nux MT and Nux 30c showed intersections at more than one point suggesting existence of molecular complexes. ES of Nux MT in CCl4 showed a red shift when 90% ethanol was added indicating molecular complexation and charge transfer interaction between ethanol and Nux compounds. NMR spectra of Nux MT, 90% ethanol, ethanol 30c, and Nux 30c indicated a change in solution structure of the medium (90% ethanol) of Nux 30c. Nux MT and Nux 30c could reduce ethanol intake in rats. The altered solution structure of Nux 30c is thought to mimic Nux MT and produce ethanol aversion in rats.

Neuropharmacology of vision in goldfish: a review.

PubMed

Mora-Ferrer, Carlos; Neumeyer, Christa

2009-05-01

The goldfish is one of the few animals exceptionally well analyzed in behavioral experiments and also in electrophysiological and neuroanatomical investigations of the retina. To get insight into the functional organization of the retina we studied color vision, motion detection and temporal resolution before and after intra-ocular injection of neuropharmaca with known effects on retinal neurons. Bicuculline, strychnine, curare, atropine, and dopamine D1- and D2-receptor antagonists were used. The results reviewed here indicate separate and parallel processing of L-cone contribution to different visual functions, and the influence of several neurotransmitters (dopamine, acetylcholine, glycine, and GABA) on motion vision, color vision, and temporal resolution.

Important Poisonous Plants in Tibetan Ethnomedicine

PubMed Central

Ma, Lijuan; Gu, Ronghui; Tang, Li; Chen, Ze-E; Di, Rong; Long, Chunlin

2015-01-01

Tibetan ethnomedicine is famous worldwide, both for its high effectiveness and unique cultural background. Many poisonous plants have been widely used to treat disorders in the Tibetan medicinal system. In the present review article, some representative poisonous plant species are introduced in terms of their significance in traditional Tibetan medicinal practices. They are Aconitum pendulum, Strychnos nux-vomica, Datura stramonium and Anisodus tanguticus, for which the toxic chemical constituents, bioactivities and pharmacological functions are reviewed herein. The most important toxins include aconitine, strychnine, scopolamine, and anisodamine. These toxic plants are still currently in use for pain-reduction and other purposes by Tibetan healers after processing. PMID:25594733

Brunfelsia australis (Yesterday, Today, and Tomorrow tree) and Solanum poisoning in a dog.

PubMed

Clipsham, Robert

2012-01-01

A 2.5 yr old female beagle presented for acute abdominal pain and vomiting after consuming limited offerings of green potato skins. Progressive complications associated with suspected ingestion of a higher potency toxin followed within 5 hr. Subsequent investigations revealed a significant ingestion of an Australian shrub commonly called a "Yesterday, Today, and Tomorrow" tree (Brunfelsia australis). The toxic principle for this emerging toxicity is referred to as "strychnine-like" and is potentially lethal with gastrointestinal, central nervous system, and cardiac pathology. This plant is currently being aggressively promoted by United States nurserymen for its dramatic tri-colored blooms and drought resistance.

Facilitation of the flexor reflex in the cat by intrathecal injection of catecholamines

PubMed Central

Dhawan, B. N.; Sharma, J. N.

1970-01-01

1. Effects of some α- and β-adrenoceptor stimulants and antagonists were investigated on flexor reflex (FR) in chloralosed cats. 2. Noradrenaline (NA) produced facilitation of FR which was dose-dependent and reproducible and was blocked by α-adrenoceptor blocking agents. 3. Strychnine also produced facilitation of FR but the response was unaffected by α-adrenoceptor blocking agents. 4. Metaraminol and α-methyl-noradrenaline had little effect on FR but blocked the NA response. 5. β-adrenoceptor stimulants and antagonists had neither any effect on FR nor modified the NA response. 6. Vasopressin and histamine also failed to modify FR. 7. Possibility of α-adrenoceptors in the neurones integrating FR is suggested. PMID:4395376

Glycine Transporters and Their Inhibitors

NASA Astrophysics Data System (ADS)

Gilfillan, Robert; Kerr, Jennifer; Walker, Glenn; Wishart, Grant

Glycine plays a ubiquitous role in many biological processes. In the central nervous system it serves as an important neurotransmitter acting as an agonist at strychnine-sensitive glycine receptors and as an essential co-agonist with glutamate at the NMDA receptor complex. Control of glycine concentrations in the vicinity of these receptors is mediated by the specific glycine transporters, GlyT1 and GlyT2. Inhibition of these transporters has been postulated to be of potential benefit in several therapeutic indications including schizophrenia and pain. In this review we discuss our current knowledge of glycine transporters and focus on recent advances in the medicinal chemistry of GlyT1 and GlyT2 inhibitors.

Differential agonist sensitivity of glycine receptor α2 subunit splice variants

PubMed Central

Miller, Paul S; Harvey, Robert J; Smart, Trevor G

2004-01-01

The glycine receptor (GlyR) α2A and α2B splice variants differ by a dual, adjacent amino acid substitution from α2AV58,T59 to α2BI58,A59 in the N-terminal extracellular domain. Comparing the effects of the GlyR agonists, glycine, β-alanine and taurine, on the GlyR α2 isoforms, revealed a significant increase in potency for all three agonists at the α2B variant. The sensitivities of the splice variants to the competitive antagonist, strychnine, and to the biphasic modulator Zn2+, were comparable. In contrast, the allosteric inhibitor picrotoxin was more potent on GlyR α2A compared to GlyR α2B receptors. Coexpression of α2A or α2B subunits with the GlyR β subunit revealed that the higher agonist potencies observed with the α2B homomer were retained for the α2Bβ heteromer. The identical sensitivity to strychnine combined with a reduction in the maximum current induced by the partial agonist taurine at the GlyR α2A homomer, suggested that the changed sensitivity to agonists is in accordance with a modulation of agonist efficacy rather than agonist affinity. An effect on agonist efficacy was also supported by using a structural model of the GlyR, localising the region of splice variation to the proposed docking region between GlyR loop 2 and the TM2-3 loop, an area associated with channel activation. The existence of a spasmodic mouse phenotype linked to a GlyR α1A52S mutation, the equivalent position to the source of the α2 splice variation, raises the possibility that the GlyR α2 splice variants may be responsible for distinct roles in neuronal function. PMID:15302677

Contribution of GABAA, Glycine, and Opioid Receptors to Sacral Neuromodulation of Bladder Overactivity in Cats.

PubMed

Jiang, Xuewen; Fuller, Thomas W; Bandari, Jathin; Bansal, Utsav; Zhang, Zhaocun; Shen, Bing; Wang, Jicheng; Roppolo, James R; de Groat, William C; Tai, Changfeng

2016-12-01

In α-chloralose-anesthetized cats, we examined the role of GABA A , glycine, and opioid receptors in sacral neuromodulation-induced inhibition of bladder overactivity elicited by intravesical infusion of 0.5% acetic acid (AA). AA irritation significantly (P < 0.01) reduced bladder capacity to 59.5 ± 4.8% of saline control. S1 or S2 dorsal root stimulation at threshold intensity for inducing reflex twitching of the anal sphincter or toe significantly (P < 0.01) increased bladder capacity to 105.3 ± 9.0% and 134.8 ± 8.9% of saline control, respectively. Picrotoxin, a GABA A receptor antagonist administered i.v., blocked S1 inhibition at 0.3 mg/kg and blocked S2 inhibition at 1.0 mg/kg. Picrotoxin (0.4 mg, i.t.) did not alter the inhibition induced during S1 or S2 stimulation, but unmasked a significant (P < 0.05) poststimulation inhibition that persisted after termination of stimulation. Naloxone, an opioid receptor antagonist (0.3 mg, i.t.), significantly (P < 0.05) reduced prestimulation bladder capacity and removed the poststimulation inhibition. Strychnine, a glycine receptor antagonist (0.03-0.3 mg/kg, i.v.), significantly (P < 0.05) increased prestimulation bladder capacity but did not reduce sacral S1 or S2 inhibition. After strychnine (0.3 mg/kg, i.v.), picrotoxin (0.3 mg/kg, i.v.) further (P < 0.05) increased prestimulation bladder capacity and completely blocked both S1 and S2 inhibition. These results indicate that supraspinal GABA A receptors play an important role in sacral neuromodulation of bladder overactivity, whereas glycine receptors only play a minor role to facilitate the GABA A inhibitory mechanism. The poststimulation inhibition unmasked by blocking spinal GABA A receptors was mediated by an opioid mechanism. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Transient Receptor Potential Vanilloid 4 Activation-Induced Increase in Glycine-Activated Current in Mouse Hippocampal Pyramidal Neurons.

PubMed

Qi, Mengwen; Wu, Chunfeng; Wang, Zhouqing; Zhou, Li; Men, Chen; Du, Yimei; Huang, Songming; Chen, Lei; Chen, Ling

2018-01-01

Glycine plays an important role in regulating hippocampal inhibitory/ excitatory neurotransmission through activating glycine receptors (GlyRs) and acting as a co-agonist of N-methyl-d-aspartate-type glutamate receptors. Activation of transient receptor potential vanilloid 4 (TRPV4) is reported to inhibit hippocampal A-type γ-aminobutyric acid receptor, a ligand-gated chloride ion channel. GlyRs are also ligand-gated chloride ion channels and this paper aimed to explore whether activation of TRPV4 could modulate GlyRs. Whole-cell patch clamp recording was employed to record glycine-activated current (IGly) and Western blot was conducted to assess GlyRs subunits protein expression. Application of TRPV4 agonist (GSK1016790A or 5,6-EET) increased IGly in mouse hippocampal CA1 pyramidal neurons. This action was blocked by specific antagonists of TRPV4 (RN-1734 or HC-067047) and GlyR (strychnine), indicating that activation of TRPV4 increases strychnine-sensitive GlyR function in mouse hippocampal pyramidal neurons. GSK1016790A-induced increase in IGly was significantly attenuated by protein kinase C (PKC) (BIM II or D-sphingosine) or calcium/calmodulin-dependent protein kinase II (CaMKII) (KN-62 or KN-93) antagonists but was unaffected by protein kinase A or protein tyrosine kinase antagonists. Finally, hippocampal protein levels of GlyR α1 α2, α3 and β subunits were not changed by treatment with GSK1016790A for 30 min or 1 h, but GlyR α2, α3 and β subunits protein levels increased in mice that were intracerebroventricularly (icv.) injected with GSK1016790A for 5 d. Activation of TRPV4 increases GlyR function and expression, and PKC and CaMKII signaling pathways are involved in TRPV4 activation-induced increase in IGly. This study indicates that GlyRs may be effective targets for TRPV4-induced modulation of hippocampal inhibitory neurotransmission. © 2018 The Author(s). Published by S. Karger AG, Basel.

Implications for glycine receptors and astrocytes in ethanol-induced elevation of dopamine levels in the nucleus accumbens.

PubMed

Adermark, Louise; Clarke, Rhona B C; Olsson, Torsten; Hansson, Elisabeth; Söderpalm, Bo; Ericson, Mia

2011-01-01

Elevated dopamine levels are believed to contribute to the rewarding sensation of ethanol (EtOH), and previous research has shown that strychnine-sensitive glycine receptors in the nucleus accumbens (nAc) are involved in regulating dopamine release and in mediating the reinforcing effects of EtOH. Furthermore, the osmoregulator taurine, which is released from astrocytes treated with EtOH, can act as an endogenous ligand for the glycine receptor, and increase extracellular dopamine levels. The aim of this study was to address if EtOH-induced swelling of astrocytes could contribute to elevated dopamine levels by increasing the extracellular concentration of taurine. Cell swelling was estimated by optical sectioning of fluorescently labeled astrocytes in primary cultures from rat, and showed that EtOH (25-150 mM) increased astrocyte cell volumes in a concentration- and ion-dependent manner. The EtOH-induced cell swelling was inhibited in cultures treated with the Na(+) /K(+) /2Cl⁻ cotransporter blocker furosemide (1 mM), Na(+) /K(+) -ATPase inhibitor ouabain (0.1 mM), potassium channel inhibitor BaCl₂ (50 µM) and in cultures containing low extracellular sodium concentration (3 mM). In vivo microdialysis performed in the nAc of awake and freely moving rats showed that local treatment with EtOH enhanced the concentrations of dopamine and taurine in the microdialysate, while glycine and β-alanine levels were not significantly modulated. EtOH-induced dopamine release was antagonized by local treatment with the glycine receptor antagonist strychnine (20 µM) or furosemide (100 µM or 1 mM). Furosemide also prevented EtOH-induced taurine release in the nAc. In conclusion, our data suggest that extracellular concentrations of dopamine and taurine are interconnected and that swelling of astrocytes contributes to the acute rewarding sensation of EtOH. © 2010 The Authors, Addiction Biology © 2010 Society for the Study of Addiction.

Adolf Hitler's medical care.

PubMed

Doyle, D

2005-02-01

For the last nine years of his life Adolf Hitler, a lifelong hypochondriac had as his physician Dr Theodor Morell. Hitler's mood swings, Parkinson's disease, gastro-intestinal symptoms, skin problems and steady decline until his suicide in 1945 are documented by reliable observers and historians, and in Morell's diaries. The bizarre and unorthodox medications given to Hitler, often for undisclosed reasons, include topical cocaine, injected amphetamines, glucose, testosterone, estradiol, and corticosteroids. In addition, he was given a preparation made from a gun cleaner, a compound of strychnine and atropine, an extract of seminal vesicles, and numerous vitamins and 'tonics'. It seems possible that some of Hitler's behaviour, illnesses and suffering can be attributed to his medical care. Whether he blindly accepted such unorthodox medications or demanded them is unclear.

Collective synthesis of natural products by means of organocascade catalysis

PubMed Central

Jones, Spencer B.; Simmons, Bryon; Mastracchio, Anthony; MacMillan, David W. C.

2012-01-01

Organic chemists are now able to synthesize small quantities of almost any known natural product, given sufficient time, resources and effort. However, translation of the academic successes in total synthesis to the large-scale construction of complex natural products and the development of large collections of biologically relevant molecules present significant challenges to synthetic chemists. Here we show that the application of two nature-inspired techniques, namely organocascade catalysis and collective natural product synthesis, can facilitate the preparation of useful quantities of a range of structurally diverse natural products from a common molecular scaffold. The power of this concept has been demonstrated through the expedient, asymmetric total syntheses of six well-known alkaloid natural products: strychnine, aspidospermidine, vincadifformine, akuammicine, kopsanone and kopsinine. PMID:21753848

Application of hydroxy aluminum treated clays to waste water treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nolan, T.F.; Fogler, H.S.

1985-01-01

Concern over the possible health effects of chlorinated biphenyls and dibenzodioxins has a scientific basis. Polychlorinated biphenyls are known mutagens and tetragens. The toxicological properties of 2,3,7,8-TCDD are well documented. One study found that 2,3,7,8-TCDD had higher inherent toxicity for mice than better known poisons; sodium cyanide, strychnine, and diphtheria toxin. It is apparent that development of technologies for the reduction of chlorinated polycyclics in the environment is desirable. It has been demonstrated that hydroxyl aluminum treatment of clay can produce an extremely powerful sorbent; even more powerful for octachlorodibenzodioxin than previously reported. The results indicate that the treatment proceduremore » is effective for several different clays.« less

Synthesis of heteroaromatic tropeines and heterogeneous binding to glycine receptors.

PubMed

Maksay, Gábor; Vincze, Zoltán; Nemes, Péter

2009-10-01

Heteroaromatic carboxylic esters of (nor)tropine were synthesized. Tropine esters displaced [(3)H]strychnine binding to glycine receptors of rat spinal cord with low Hill slopes. Two-site displacement resulted in nanomolar IC(50,1) and micromolar IC(50,2) values, and IC(50,2)/IC(50,1) ratios up to 615 depending on the heteroaromatic rings and N-methyl substitution. Nortropeines displayed high affinity and low heterogeneity. IC(50,1) and IC(50,2) values of tropeines did not correlate suggesting different binding modes/sites. Glycine potentiated only the nanomolar displacement reflecting positive allosteric interactions and potentiation of ionophore function. Affinities of three (nor)tropeines were different for glycine receptors but identical for 5-HT(3) receptors.

Collective synthesis of natural products by means of organocascade catalysis.

PubMed

Jones, Spencer B; Simmons, Bryon; Mastracchio, Anthony; MacMillan, David W C

2011-07-13

Organic chemists are now able to synthesize small quantities of almost any known natural product, given sufficient time, resources and effort. However, translation of the academic successes in total synthesis to the large-scale construction of complex natural products and the development of large collections of biologically relevant molecules present significant challenges to synthetic chemists. Here we show that the application of two nature-inspired techniques, namely organocascade catalysis and collective natural product synthesis, can facilitate the preparation of useful quantities of a range of structurally diverse natural products from a common molecular scaffold. The power of this concept has been demonstrated through the expedient, asymmetric total syntheses of six well-known alkaloid natural products: strychnine, aspidospermidine, vincadifformine, akuammicine, kopsanone and kopsinine. ©2011 Macmillan Publishers Limited. All rights reserved

Strychnine-sensitive modulation is selective for non-noxious somatosensory input in the spinal cord of the rat.

PubMed

Sherman, S E; Loomis, C W

1996-08-01

Touch-evoked allodynia, an important symptom of clinical neural injury pain, can be modelled acutely and reversibly in the urethane-anesthetized rat using intrathecal (i.t.) strychnine (STR). Allodynia, after i.t. STR (40 micrograms), is manifest as a significant enhancement of cardiovascular and motor responses evoked by normally innocuous brushing of the hair (hair deflection), as compared to responses evoked by either hair deflection after i.t. saline (SAL), or to i.t. STR (40 micrograms) with no tactile stimulus. The present study investigated: (1) the pharmacology of afferent neural inputs involved in STR-dependent allodynia using neonatal capsaicin and the non-NMDA receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline (NBQX); and (2) the effect of i.t. STR on responses evoked by peripheral noxious stimulation. Neonatal capsaicin (25 mg/kg, s.c., post-natal day (PND) 1, and 50 mg/kg, s.c., PND 2, 3, 4, 11, 25, 55 and 85) significantly attenuated the responses evoked by noxious mechanical, thermal or chemical stimuli, but had no effect on STR-dependent allodynia. All hair deflection-evoked, STR-dependent responses were dose-dependently inhibited by i.t. NBQX. The ED50 values and 95% confidence intervals were 10.4 micrograms (5.5-19.6) for the motor withdrawal response, 14.4 micrograms (8.6-24.0) for changes in MAP and 12.2 micrograms (6.8-21.8) for changes in HR. Cortical EEG synchrony was unchanged by i.t. NBQX confirming its spinal locus of action. Intrathecal STR neither reduced nor enhanced the responses elicited by noxious stimuli in capsaicin- or vehicle-pretreated rats. These results indicate that STR-dependent allodynia is initiated by primary afferents not normally involved in nociception (possibly A beta-fibers), and that STR-sensitive modulation in the spinal cord is selective for non-noxious sensory input. The sensitivity of STR-dependent allodynia to non-NMDA receptor antagonists, and the failure of i.t. STR to produce hyperalgesia to mechanical, thermal or chemical noxious stimuli, confirm the independence of nociceptive pathways and STR-sensitive afferent inputs in this model.

Glycinergic Pathways of the Central Auditory System and Adjacent Reticular Formation of the Rat.

NASA Astrophysics Data System (ADS)

Hunter, Chyren

The development of techniques to visualize and identify specific transmitters of neuronal circuits has stimulated work on the characterization of pathways in the rat central nervous system that utilize the inhibitory amino acid glycine as its neurotransmitter. Glycine is a major inhibitory transmitter in the spinal cord and brainstem of vertebrates where it satisfies the major criteria for neurotransmitter action. Some of these characteristics are: uneven distribution in brain, high affinity reuptake mechanisms, inhibitory neurophysiological actions on certain neuronal populations, uneven receptor distribution and the specific antagonism of its actions by the convulsant alkaloid strychnine. Behaviorally, antagonism of glycinergic neurotransmission in the medullary reticular formation is linked to the development of myoclonus and seizures which may be initiated by auditory as well as other stimuli. In the present study, decreases in the concentration of glycine as well as the density of glycine receptors in the medulla with aging were found and may be responsible for the lowered threshold for strychnine seizures observed in older rats. Neuroanatomical pathways in the central auditory system and medullary and pontine reticular formation (RF) were investigated using retrograde transport of tritiated glycine to identify glycinergic pathways; immunohistochemical techniques were used to corroborate the location of glycine neurons. Within the central auditory system, retrograde transport studies using tritiated glycine demonstrated an ipsilateral glycinergic pathway linking nuclei of the ascending auditory system. This pathway has its cell bodies in the medial nucleus of the trapezoid body (MNTB) and projects to the ventrocaudal division of the ventral nucleus of the lateral lemniscus (VLL). Collaterals of this glycinergic projection terminate in the ipsilateral lateral superior olive (LSO). Other glycinergic pathways found were afferent to the VLL and have their origin in the ventral and lateral nuclei of the trapezoid body (MVPO and LVPO). Bilateral projections from the nucleus reticularis pontis oralis (RPOo), to the VLL were also identified as glycinergic. This projection may link motor output systems to ascending auditory input, generating the auditory behavioral responses seen with glycine antagonism in animal models of myoclonus and seizure.

[Parkinson's disease of Adolf Hitler and its influence in the development of World War Second].

PubMed

Guerrero, A L

2003-03-01

Adolf Hitler very probably suffered from Parkinson's disease. The first symptoms of it began to appear in 1937/1938. It is likely that its appearance, and the fear that it caused regarding his survival, lead Hitler to advance his initial projects of military expansion of the great Germany beginning in 1943. Thus, the Second World War broke out in 1939, perhaps quite before the time in which Germany would be prepared. Chronic treatment carried out with opiates, cocaine, amphetamines, and strychnine may very well be related with a very abnormal judgement of the problems and absence of trust in the advice of his team. With this, he would make military decisions that would end up being ill-fated for his interests and which, after 1942, would lead to a change in the course of the war.

Binding site stoichiometry and the effects of phosphorylation on human α1 homomeric glycine receptors

PubMed Central

Gentet, Luc J; Clements, John D

2002-01-01

The kinetic properties of the human α1 homomeric glycine receptor were investigated. Receptors were expressed in HEK 293 cells, and glycine was applied to outside-out membrane patches with sub-millisecond solution exchange. The activation time course of the glycine response was used to investigate receptor stoichiometry. The unbinding of three strychnine molecules and the cooperative binding of two glycine molecules were required to activate the channel. The effects of phosphorylation on glycine receptor kinetics were investigated by pretreating cells with phosphorylators or with phosphatases. Phosphorylation accelerated desensitisation, but slowed deactivation and recovery from desensitisation. A chemical-kinetic model was developed that reproduced the experimental observations. The model suggests that only three binding sites on the glycine channel are functional, while the remaining two binding sites are ‘silent’, possibly due to strong negative cooperativity. PMID:12356883

DDT poisoning in a Cooper's hawk collected in 1980

USGS Publications Warehouse

Prouty, Richard M.; Pattee, Oliver H.; Schmeling, Shelia K.

1982-01-01

In April 1980, a Cooper's hawk (Accipiter cooperii) was found on the ground in Lakewood, Colorado, unable to fly and in convulsion. The bird died shortly thereafter. The hawk was packed in dry ice and shipped air express to the Fish and Wildlife Service, U. S. Department of the Interior, National Wildlife Health Laboratory, Madison, Wisconsin, for necropsy. Following necropsy, the brain, gastrointestinal tract, and remaining carcass except skin, feet, wings, liver, and kidney were packed in dry ice and shipped air express to the Patuxent Wildlife Research Center, Laurel, Maryland, for chemical residue analysis. Because the bird's behavior before death suggested some form of poisoning, the kidney was assayed for thallium, the liver for lead, and the gastrointestinal tract for strychnine, sodium fluoroacetate, and arsenic. When these assays proved negative, the bird was analyzed for organochlorine pesticides. Necropsy findings and pesticide residue analyses are reported here.

A retrospective study of postmortem findings in red-tailed hawks

USGS Publications Warehouse

Franson, J.C.; Thomas, N.J.; Smith, M.R.; Robbins, A.H.; Newman, S.; McCartin, P.C.

1996-01-01

We studied necropsy results from carcasses of 163 red-tailed hawks (Buteo jamaicensis) submitted to the National Wildlife Health Center from 1975 through 1992. The most frequent postmortem finding was emaciation of unknown etiology, diagnosed in 33 (20%) carcasses. Proportionally more juveniles than adults were emaciated. Evidence of non-gunshot trauma, often suggestive of collision with vehicles or structures near roadways, was found in 29 (18%) birds. Of 25 (15%) toxicoses, 20 were attributed to agricultural pesticides, including famphur (4), fenthion (3), carbofuran (2), phosphamidon (2), endrin (1), and unidentified organophosphorus compounds (8). Lead and strychnine poisoning were diagnosed in two birds each, and selenium poisoning in one. Diseases, including aspergillosis, tuberculosis, pasteurellosis, and pox, were found in 21 (13%) hawks. Gunshot and electrocution were each diagnosed in six (4%) birds, one (0.6%) was trapped, miscellaneous conditions were found in 10 (6%), and no diagnosis could be determined for 32 (19%) of the carcasses.

Transmitters and pathways mediating inhibition of spinal itch-signaling neurons by scratching and other counterstimuli.

PubMed

Akiyama, Tasuku; Iodi Carstens, Mirela; Carstens, Earl

2011-01-01

Scratching relieves itch, but the underlying neural mechanisms are poorly understood. We presently investigated a role for the inhibitory neurotransmitters GABA and glycine in scratch-evoked inhibition of spinal itch-signaling neurons in a mouse model of chronic dry skin itch. Superficial dorsal horn neurons ipsilateral to hindpaw dry skin treatment exhibited a high level of spontaneous firing that was significantly attenuated by cutaneous scratching, pinch and noxious heat. Scratch-evoked inhibition was nearly abolished by spinal delivery of the glycine antagonist, strychnine, and was markedly attenuated by respective GABA(A) and GABA(B) antagonists bicuculline and saclofen. Scratch-evoked inhibition was also significantly attenuated (but not abolished) by interruption of the upper cervical spinal cord, indicating the involvement of both segmental and suprasegmental circuits that engage glycine- and GABA-mediated inhibition of spinal itch-signaling neurons by noxious counterstimuli.

Glycinergic Input to the Mouse Basal Forebrain Cholinergic Neurons

PubMed Central

Bardóczi, Zsuzsanna; Pál, Balázs; Kőszeghy, Áron; Wilheim, Tamás; Záborszky, László; Liposits, Zsolt

2017-01-01

The basal forebrain (BF) receives afferents from brainstem ascending pathways, which has been implicated first by Moruzzi and Magoun (1949) to induce forebrain activation and cortical arousal/waking behavior; however, it is very little known about how brainstem inhibitory inputs affect cholinergic functions. In the current study, glycine, a major inhibitory neurotransmitter of brainstem neurons, and gliotransmitter of local glial cells, was tested for potential interaction with BF cholinergic (BFC) neurons in male mice. In the BF, glycine receptor α subunit-immunoreactive (IR) sites were localized in choline acetyltransferase (ChAT)-IR neurons. The effect of glycine on BFC neurons was demonstrated by bicuculline-resistant, strychnine-sensitive spontaneous IPSCs (sIPSCs; 0.81 ± 0.25 × 10−1 Hz) recorded in whole-cell conditions. Potential neuronal as well as glial sources of glycine were indicated in the extracellular space of cholinergic neurons by glycine transporter type 1 (GLYT1)- and GLYT2-IR processes found in apposition to ChAT-IR cells. Ultrastructural analyses identified synapses of GLYT2-positive axon terminals on ChAT-IR neurons, as well as GLYT1-positive astroglial processes, which were localized in the vicinity of synapses of ChAT-IR neurons. The brainstem raphe magnus was determined to be a major source of glycinergic axons traced retrogradely from the BF. Our results indicate a direct effect of glycine on BFC neurons. Furthermore, the presence of high levels of plasma membrane glycine transporters in the vicinity of cholinergic neurons suggests a tight control of extracellular glycine in the BF. SIGNIFICANCE STATEMENT Basal forebrain cholinergic (BFC) neurons receive various activating inputs from specific brainstem areas and channel this information to the cortex via multiple projections. So far, very little is known about inhibitory brainstem afferents to the BF. The current study established glycine as a major regulator of BFC neurons by (1) identifying glycinergic neurons in the brainstem projecting to the BF, (2) showing glycine receptor α subunit-immunoreactive (IR) sites in choline acetyltransferase (ChAT)-IR neurons, (3) demonstrating glycine transporter type 2 (GLYT2)-positive axon terminals synapsing on ChAT-IR neurons, and (4) localizing GLYT1-positive astroglial processes in the vicinity of synapses of ChAT-IR neurons. The effect of glycine on BFC neurons was demonstrated by bicuculline-resistant, strychnine-sensitive spontaneous IPSCs recorded in whole-cell conditions. PMID:28874448

Properties of synaptic transmission from the reticular formation dorsal to the facial nucleus to trigeminal motoneurons during early postnatal development in rats.

PubMed

Gemba-Nishimura, A; Inoue, T; Nakamura, S; Nakayama, K; Mochizuki, A; Shintani, S; Yoshimura, S

2010-03-31

We previously reported that electrical stimulation of the reticular formation dorsal to the facial nucleus (RdVII) elicited excitatory masseter responses at short latencies and that RdVII neurons were antidromically activated by stimulation of the trigeminal motor nucleus (MoV), suggesting that excitatory premotor neurons targeting the MoV are likely located in the RdVII. We thus examined the properties of synaptic transmission from the RdVII to jaw-closing and jaw-opening motoneurons in horizontal brainstem preparations from developing rats using voltage-sensitive dye, patch-clamp recordings and laser photostimulation. Electrical stimulation of the RdVII evoked optical responses in the MoV. Combined bath application of the non-N-methyl-d-aspartate (non-NMDA) receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and the NMDA receptor antagonist DL-2-amino-5-phosphonopentanoic acid (APV) reduced these optical responses, and addition of the glycine receptor antagonist strychnine and the GABA(A) receptor antagonist bicuculline further reduced the remaining responses. Electrical stimulation of the RdVII evoked postsynaptic currents (PSCs) in all 19 masseter motoneurons tested in postnatal day (P)1-4 rats, and application of CNQX and the NMDA receptor antagonist (+/-)-3(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) reduced the PSC amplitudes by more than 50%. In the presence of CNQX and CPP, the GABA(A) receptor antagonist SR95531 further reduced PSC amplitude, and addition of strychnine abolished the remaining PSCs. Photostimulation of the RdVII with caged glutamate also evoked PSCs in masseter motoneurons of P3-4 rats. In P8-11 rats, electrical stimulation of the RdVII also evoked PSCs in all 14 masseter motoneurons tested, and the effects of the antagonists on the PSCs were similar to those in P1-4 rats. On the other hand, RdVII stimulation evoked PSCs in only three of 16 digastric motoneurons tested. These results suggest that both neonatal and juvenile jaw-closing motoneurons receive strong synaptic inputs from the RdVII through activation of glutamate, glycine and GABA(A) receptors, whereas inputs from the RdVII to jaw-opening motoneurons seem to be weak. Copyright 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

An unexpected reaction pathway in the synthesis of the ABCE framework of strychnine-type alkaloids - A multidisciplinary study

NASA Astrophysics Data System (ADS)

Šoral, Michal; Markus, Jozef; Doháňošová, Jana; Šoralová, Stanislava; Dvoranová, Dana; Chyba, Andrej; Moncol, Ján; Berkeš, Dušan; Liptaj, Tibor

2017-01-01

Acid-catalyzed cyclization of spirocyclic 1‧-benzyl-2‧-(prop-2-en-1-yl)spiro[indole-3,3‧-pyrrolidine]-5‧-one (1) was performed. The pentacyclic product of Povarov-like imino-Diels-Alder reaction was isolated in high yield instead of expected tetracyclic aza-Prins intermediate. The unusual exotic alkaloid-type structure of the resulting molecule 2 was unambiguously confirmed by a detailed NMR analysis using a set of 2D NMR spectra including an INADEQUATE experiment. The relative configuration of 2 was predicted from the synthesis mechanism and DFT geometry calculations and independently confirmed using NOESY and residual dipolar coupling (RDC) assisted NMR analysis in stretched crosslinked polystyrene gels. The reversibility of the cycloaddition in aprotic solvents was observed. A new reaction pathway yielding a rare 6-5-5-5 tetracyclic spiroindoline 3 was suggested. The relative configuration within the tetracyclic framework was ultimately proved using Single-crystal X-ray diffraction analysis of compound 4.

Anticonvulsive activity of Albizzia lebbeck, Hibiscus rosa sinesis and Butea monosperma in experimental animals.

PubMed

Kasture, V S; Chopde, C T; Deshmukh, V K

2000-07-01

The ethanolic extracts of leaves of Albizzia lebbeck and flowers of Hibiscus rosa sinesis and the petroleum ether extract of flowers of Butea monosperma exhibited anticonvulsant activity. The bioassay guided fractionation indicated that the anticonvulsant activity lies in the methanolic fraction of chloroform soluble part of ethanolic extract of the leaves of A. lebbeck, acetone soluble part of ethanolic extract of H. rosa sinesis flowers and acetone soluble part of petroleum ether extract of B. monosperma flowers. The fractions protected animals from maximum electro shock, electrical kindling and pentylenetetrazole-induced convulsions in mice. The fractions also inhibited convulsions induced by lithium-pilocarpine and electrical kindling. However, they failed to protect animals from strychnine-induced convulsions. The fractions antagonised the behavioral effects of D-amphetamine and potentiated the pentobarbitone-induced sleep. The fractions raised brain contents of gamma-aminobutyric acid (GABA) and serotonin. These fractions were found to be anxiogenic and general depressant of central nervous system.

Predator Bounties in Western Canada Cause Animal Suffering and Compromise Wildlife Conservation Efforts

PubMed Central

Proulx, Gilbert; Rodtka, Dwight

2015-01-01

Although predation bounty programs (rewards offered for capturing or killing an animal) ended more than 40 years ago in Canada, they were reintroduced in Alberta in 2007 by hunting, trapping, and farming organizations, municipalities and counties, and in 2009 in Saskatchewan, by municipal and provincial governments and the Saskatchewan Cattlemen’s Association. Bounty hunters use inhumane and non-selective killing methods such as shooting animals in non-vital regions, and killing neck snares and strychnine poisoning, which cause suffering and delayed deaths. They are unselective, and kill many non-target species, some of them at risk. Predator bounty programs have been found to be ineffective by wildlife professionals, and they use killing methods that cause needless suffering and jeopardize wildlife conservation programs. Our analysis therefore indicates that government agencies should not permit the implementation of bounty programs. Accordingly, they must develop conservation programs that will minimize wildlife-human conflicts, prevent the unnecessary and inhumane killing of animals, and ensure the persistence of all wildlife species. PMID:26479482

In vivo Antimalarial and Antitrypanosomal Activity of Strychnogucine B, a Bisindole Alkaloid from Strychnos icaja.

PubMed

Beaufay, Claire; Ledoux, Allison; Jansen, Olivia; Bordignon, Annélise; Zhao, Senzhi; Teijaro, Christiana N; Andrade, Rodrigo B; Quetin-Leclercq, Joëlle; Frédérich, Michel

2018-06-21

Strychnogucine B is a bisindole alkaloid previously isolated from Strychnos icaja that possesses promising in vitro antiplasmodial properties. This compound was synthesized in four steps from (-)-strychnine. As no acute toxicity was observed at the highest tested cumulative dose of 60 mg/kg, its in vivo antimalarial activity was determined intraperitoneally at 30 mg/kg/d in a Plasmodium berghei murine model. In the Peters's 4-d suppressive test, this alkaloid suppressed the parasitaemia by almost 36% on day 5 and 60% on day 7 compared to vehicle-treated mice. In addition to this interesting antimalarial activity, it showed moderate in vitro antitrypanosomal activity but no in vivo activity in an acute Trypanosoma brucei model. It was also inactive in vitro on Leishmania mexicana promastigotes. This highlights its selective antimalarial efficacy and leads to further investigation to assess its potential as new antimalarial lead compound. Georg Thieme Verlag KG Stuttgart · New York.

Predator Bounties in Western Canada Cause Animal Suffering and CompromiseWildlife Conservation Efforts.

PubMed

Proulx, Gilbert; Rodtka, Dwight

2015-10-19

Although predation bounty programs (rewards offered for capturing or killing an animal) ended more than 40 years ago in Canada, they were reintroduced in Alberta in 2007 by hunting, trapping, and farming organizations, municipalities and counties, and in 2009 in Saskatchewan, by municipal and provincial governments and the Saskatchewan Cattlemen's Association. Bounty hunters use inhumane and non-selective killing methods such as shooting animals in non-vital regions, and killing neck snares and strychnine poisoning, which cause suffering and delayed deaths. They are unselective, and kill many non-target species, some of them at risk. Predator bounty programs have been found to be ineffective by wildlife professionals, and they use killing methods that cause needless suffering and jeopardize wildlife conservation programs. Our analysis therefore indicates that government agencies should not permit the implementation of bounty programs. Accordingly, they must develop conservation programs that will minimize wildlife-human conflicts, prevent the unnecessary and inhumane killing of animals, and ensure the persistence of all wildlife species.

[Natural toxins in inter- and intraspecies interaction of human being (elements of ethnotoxinology)].

PubMed

Gelashvili, D B

2002-01-01

The author considers the application of natural toxins as arrow poison by Homo sapiens from ancient time till today for hunting and ethnic wars on the example of natives of Asia, Africa, South America and Oceania. Geographic isolation was important determining the spectrum of natural toxin sources and the methods of their application. Cellular and molecular mechanisms of arrow poisons effects are considered in biogeographical context: aconitin and strychnin in Asia, diamphotoxin in Africa, indole alcaloids of plants and steroid alcaloids of amphibian in Central and South America, palytoxin in Oceania islands. High efficiency and selective effect of natural toxins allow to use them as molecular markers in current studies of functional membrane architecture and cellular structures. Great differences in pace of civilization development leads to the co-existence at the beginning of the XXI century ethnic groups that use natural toxins as arrow poison and human beings that use the same toxins in fundamental and applied investigations within international scientific society.

Theanine, gamma-glutamylethylamide, a unique amino acid in tea leaves, modulates neurotransmitter concentrations in the brain striatum interstitium in conscious rats.

PubMed

Yamada, T; Terashima, T; Kawano, S; Furuno, R; Okubo, T; Juneja, L R; Yokogoshi, H

2009-01-01

Theanine (gamma-glutamylethylamide) is one of the major amino acid components in green tea and can pass through the blood-brain barrier. Recent studies suggest that theanine affects the mammalian central nervous system; however, the detailed mechanism remains unclear. In this study, we demonstrated the effect of theanine on neurotransmission in the brain striatum by in vivo brain microdialysis. Theanine injection into the rat brain striatum did not increase the concentration of excitatory neurotransmitters in the perfusate. On the other hand, theanine injection increased the concentration of glycine in the perfusate. Because it has been reported that theanine promotes dopamine release in the rat striatum, we investigated the glycine and dopamine concentrations in the perfusate. Co-injection of glycine receptor antagonist, strychnine, reduced theanine-induced changes in dopamine. Moreover, AMPA receptor antagonist, which regulates glycine and GABA release from glia cells, inhibited these effects of theanine and this result was in agreement with the known inhibitory effect of theanine at AMPA receptors.

Desert bighorn sheep mortality due to presumptive type C botulism in California

USGS Publications Warehouse

Swift, P.K.; Wehausen, J.D.; Ernest, H.B.; Singer, R.S.; Pauli, A.M.; Kinde, H.; Rocke, T.E.; Bleich, V.C.

2000-01-01

During a routine telemetry flight of the Mojave Desert (California, USA) in August 1995, mortality signals were detected from two of 12 radio-collared female desert bighorn sheep (Ovis canadensis) in the vicinity of Old Dad Peak in San Bernardino County (California). A series of field investigations determined that at least 45 bighorn sheep had died near two artificial water catchments (guzzlers), including 13 bighorn sheep which had presumably drowned in a guzzler tank. Samples from water contaminated by decomposing bighorn sheep carcasses and hemolyzed blood from a fresh bighorn sheep carcass were tested for the presence of pesticides, heavy metals, strychnine, blue-green algae, Clostridium botulinum toxin, ethylene glycol, nitrates, nitrites, sodium, and salts. Mouse bioassay and enzyme-linked immunosorbent assay detected type C botulinum toxin in the hemolyzed blood and in fly larvae and pupae. This, coupled with negative results from other analyses, led us to conclude that type C botulinum poisoning was most likely responsible for the mortality of bighorn sheep outside the guzzler tank.

Antiseizure Effects of Ketogenic Diet on Seizures Induced with Pentylenetetrazole, 4-Aminopyridine and Strychnine in Wistar Rats.

PubMed

Sanya, E O; Soladoye, A O; Desalu, O O; Kolo, P M; Olatunji, L A; Olarinoye, J K

2017-03-06

The ketogenic diet (KD) is a cheap and effective alternative therapy for most epilepsy. There are paucity of experimental data in Nigeria on the usefulness of KD in epilepsy models. This is likely to be responsible for the poor clinical acceptability of the diet in the country. This study therefore aimed at providing experimental data on usefulness of KD on seizure models.  The study used 64 Wistar rats that were divided into two dietary groups [normal diet (ND) and ketogenic diet (KD)]. Animal in each group were fed for 35days. Medium chain triglyceride ketogenic diet (MCT-KD) was used and it consisted of 15% carbohydrate in normal rat chow long with 5ml sunflower oil (25% (v/w). The normal diet was the usual rat chow. Seizures were induced with one of Pentelyntetrazole (PTZ), 4-Aminopyridine (AP) and Strychnine (STR). Fasting glucose, ketosis level and serum chemistry were determined and seizure parameters recorded. Serum ketosis was significantly higher in MCT-KD-fed rats (12.7 ±2.6) than ND-fed (5.17±0.86) rats. Fasting blood glucose was higher in ND-fed rats (5.3±0.9mMol/l) than in MCT-KD fed rats (5.1±0.5mMol/l) with p=0.9. Seizure latency was significantly prolonged in ND-fed compared with MCT-KD fed rats after PTZ-induced seizures (61±9sec vs 570±34sec) and AP-induced seizures (49±11sec vs 483±41sec). The difference after Str-induced seizure (51±7 vs 62±8 sec) was not significan. The differences in seizure duration between ND-fed and MCT-KD fed rats with PTZ (4296±77sec vs 366±46sec) and with AP (5238±102sec vs 480±67sec) were significant (p<0.05), but not with STR (3841±94sec vs 3510±89sec) respectively. The mean serum Na+ was significantly higher in MCT-KD fed (141.7±2.1mMol/l) than ND-fed rats (137±2.3mMol/l). There was no significant difference in mean values of other serum electrolytes between the MCT-KD fed and ND-fed animals. MCT-KD caused increase resistance to PTZ-and AP-induced seizures, but has no effect on STR-induced seizures. This antiseizure property is probably mediated through GABAergic receptors (PTZ effect) and blockade of membrane bound KATP channels (AP effect) with some enhancement by serum ketosis.

Anticonvulsant properties of methanol leaf extract of Laggera Aurita Linn. F. (Asteraceae) in laboratory animals.

PubMed

Malami, S; Kyari, H; Danjuma, N M; Ya'u, J; Hussaini, I M

2016-09-15

Preparation of Laggera aurita Linn. (Asteraceae) is widely used in traditional medicine to treat various kinds of diseases such as epilepsy, malaria, fever, pain and asthma. Its efficacy is widely acclaimed among communities in Northern Nigeria. The present study is aimed at establishing the possible anticonvulsant effects of the methanol leaf extract of Laggera aurita using acute and chronic anticonvulsant models. Median lethal dose (LD50) was determined in mice and rats via oral and intraperitoneal routes. Anticonvulsant screening of the extract was performed using maximal electroshock-induced seizure test in day-old chicks; pentylenetetrazole-, strychnine- and picrotoxin- induced seizure models in mice. Similarly; its effects on pentylenetetrazole-induce kindling in rats as well as when co-administered with fluphenamic and cyproheptadine in mice, were evaluated. Median lethal dose (LD50) values were found to be >5000mg/kg, p.o. and 2154mg/kg, i.p., each for both rats and mice. The extract showed dose dependent protection against tonic hind limb extension (THLE) and significantly (p<0.05) decreased the mean recovery from seizure in the maximal electroshock-induced seizure. In the pentylenetetrazole-induced seizure model, the extract offered 50% protection at 600mg/kg and also increased the mean onset of seizure at all doses with significant (p<0.05) increase at the highest dose (600mg/kg). Similarly the extract produced significant (p<0.05) increase in the onset of seizures in both strychnine- and picrotoxin- induced seizure models, at all the doses except at 150mg/kg for the picrotoxin model. Co-administration of fluphenamic acid (FFA) (5mg/kg) and the extract (600mg/kg) showed an enhanced effect with percentage protection of 70% while co-administration of FFA (5mg/kg) and phenytoin (5mg/kg) as well phenytoin (5mg/kg) and the extract (600mg/kg) produced an additive effect. Administration of the extract (600mg/kg), phenytoin (20mg/kg) and cyproheptadine (4mg/kg) offered 40%, 100% and 0% protection against THLE, each respectively, while co-administration of cyproheptadine (4mg/kg) and the extract (600mg/kg) as well as co-administration of cyproheptadine (4mg/kg) and phenytoin (20mg/kg) offered reduced protection of 20% and 50% each respectively. The extract at all doses reduced the severity of seizure episodes induced by PTZ-induced kindling. The results suggest that the methanol leaf extract of Laggera aurita possesses anticonvulsant and antiepileptogenic properties. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Deficiency of gustatory sensitivity to some deterrent compounds in "polyphagous" mutant strains of the silkworm, Bombyx mori.

PubMed

Asaoka, K

2000-11-01

Sawa-J, CSJ02 and N601 x C601 are selected mutant strains of Bombyx mori, which grow on various artificial diets or temporarily ingest various plant leaves. To examine the mechanisms mediating diet breadth of caterpillars, gustatory spike responses of the silkworms, called 'polyphagous" strains, were compared with normal strains, N137 x C146 and C02. There were notable differences in their feeding habits and in their sensitivity to salicin in deterrent cells in the maxillary medial styloconic sensilla and the epipharyngeal sensilla. By contrast, the deterrent cells of all strains responded similarly to strychnine nitrate in a dose-dependent manner. In additional comparisons of Sawa-J and N137 x C146, Sawa-J maxillary deterrent cells were significantly less sensitive to phloridzin, amygdalin and arbutin, but responded to some alkaloids and 20-hydroxyecdysone with similar or even higher firing rate. These results suggest that the deficiency of the sensitivity to some deterrent compounds on the deterrent cell of the polyphagous strains may be caused by mutant genes and affects the diet breadth of caterpillars.

In vitro metabolism study of Strychnos alkaloids using high-performance liquid chromatography combined with hybrid ion trap/time-of-flight mass spectrometry.

PubMed

Tian, Ji-Xin; Peng, Can; Xu, Lei; Tian, Yuan; Zhang, Zun-Jian

2013-06-01

In this report, the in vitro metabolism of Strychnos alkaloids was investigated using liquid chromatography/high-resolution mass spectrometry for the first time. Strychnine and brucine were selected as model compounds to determine the universal biotransformations of the Strychnos alkaloids in rat liver microsomes. The incubation mixtures were separated by a bidentate-C18 column, and then analyzed by on-line ion trap/time-of-flight mass spectrometry. With the assistance of mass defect filtering technique, full-scan accurate mass datasets were processed for the discovery of the related metabolites. The structural elucidations of these metabolites were achieved by comparing the changes in accurate molecular masses, calculating chemical component using Formula Predictor software and defining sites of biotransformation based upon accurate MS(n) spectral information. As a result, 31 metabolites were identified, of which 26 metabolites were reported for the first time. These biotransformations included hydroxylation, N-oxidation, epoxidation, methylation, dehydrogenation, de-methoxylation, O-demethylation, as well as hydrolysis reactions. Copyright © 2013 John Wiley & Sons, Ltd.

Calcitonin gene-related peptide enhances substance P-induced behaviors via metabolic inhibition: in vivo evidence for a new mechanism of neuromodulation.

PubMed

Mao, J; Coghill, R C; Kellstein, D E; Frenk, H; Mayer, D J

1992-03-06

The present study examined the effects of intrathecal (i.t.) injection of calcitonin gene-related peptide (CGRP) on caudally directed biting and scratching induced by i.t. substance P (SP), bombesin (BBS), strychnine (STR), and kainic acid (KA). CGRP alone (5.25, 10.5 and 21 nmol) had no effect on these behaviors, but CGRP pretreatment produced a dose-related enhancement of behaviors induced by SP or BBS, but not by KA or STR. 2-Amino-5-phosphonovaleric acid (APV, 25 nmol), a selective N-methyl-D-aspartate (NMDA) receptor antagonist, did not block the CGRP potentiation of SP and BBS induced behaviors. CGRP, however, failed to enhance scratching and biting induced by a SP analogue [pGlu5-Mephe8-MeGly9]SP(5-11) (Dime-C7) that is resistant to enzymatic degradation by SP endopeptidase. These findings demonstrate that CGRP potentiates SP induced behavioral responses via inhibition of neuropeptide degradation and that this mechanism may serve as a physiological mechanism of SP modulation.

The Glycine Transport Inhibitor Sarcosine Is an Inhibitory Glycine Receptor Agonist

PubMed Central

Zhang, Hai Xia; Lyons-Warren, Ariel; Thio, Liu Lin

2009-01-01

Summary Sarcosine is an endogenous amino acid that is a competitive inhibitor of the type I glycine transporter (GlyT1), an N-methyl-D-aspartate receptor (NMDAR) co-agonist, and an important intermediate in one-carbon metabolism. Its therapeutic potential for schizophrenia further underscores its clinical importance. The structural similarity between sarcosine and glycine and sarcosine's ability to serve as an NMDAR co-agonist led us to examine whether sarcosine is also an agonist at the inhibitory glycine receptor (GlyR). We examined this possibility using whole-cell recordings from cultured embryonic mouse hippocampal neurons and found that sarcosine evoked a dose-dependent, strychnine sensitive, Cl- current that cross-inhibited glycine currents. Sarcosine evoked this current with Li+ in the extracellular solution to block GlyT1, in neurons treated with the essentially irreversible GlyT1 inhibitor N[3-(4′-fluorophenyl)-3-(4′-phenylphenoxy)propyl]sarcosine (NFPS), and in neurons plated in the absence of glia. These results indicate that the sarcosine currents did not result from GlyT1 inhibition or heteroexchange. We conclude that sarcosine is a GlyR agonist. PMID:19619564

The glycine transport inhibitor sarcosine is an inhibitory glycine receptor agonist.

PubMed

Zhang, Hai Xia; Lyons-Warren, Ariel; Thio, Liu Lin

2009-01-01

Sarcosine is an endogenous amino acid that is a competitive inhibitor of the type I glycine transporter (GlyT1), an N-methyl-d-aspartate receptor (NMDAR) co-agonist, and an important intermediate in one-carbon metabolism. Its therapeutic potential for schizophrenia further underscores its clinical importance. The structural similarity between sarcosine and glycine and sarcosine's ability to serve as an NMDAR co-agonist led us to examine whether sarcosine is also an agonist at the inhibitory glycine receptor (GlyR). We examined this possibility using whole-cell recordings from cultured embryonic mouse hippocampal neurons and found that sarcosine evoked a dose-dependent, strychnine sensitive, Cl(-) current that cross-inhibited glycine currents. Sarcosine evoked this current with Li(+) in the extracellular solution to block GlyT1, in neurons treated with the essentially irreversible GlyT1 inhibitor N[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine (NFPS), and in neurons plated in the absence of glia. These results indicate that the sarcosine currents did not result from GlyT1 inhibition or heteroexchange. We conclude that sarcosine is a GlyR agonist.

Inhibitory effects of acetylcholine on neurones in the feline nucleus reticularis thalami.

PubMed

Ben-Ari, Y; Dingledine, R; Kanazawa, I; Kelly, J S

1976-10-01

1. Short iontophoretic pulses of acetylcholine (ACh) inhibited almost every spontaneously active cell encountered in the nucleus reticularis thalami of cats anaesthetized with a mixture of halothane, nitrous oxide and oxygen. On 200 cells the mean current needed to eject an effective inhibitory dose of ACh was 67 +/- 2 nA. When the ACh-evoked inhibition was mimicked by gamma-aminobutyric acid (GABA) or glycine on the same cell, the current required to release ACh was found to be approximately twice as great as that required to release an equally effective dose of GABA or glycine. 2. ACh inhibitions developed with a latency which was very much shorter than that for ACh excitation in cells of the ventrobasal complex. The latency of the ACh-evoked inhibition was as rapid as the onset and offset of the excitation of the same cells glutamate and their inhibition by GABA or glycine. 3. The firing pattern of ACh-inhibited neurones in the nucleus reticularis was characterized by periods of prolonged, high frequency bursts, and their mean firing frequency was 22 Hz. Raster dot displays and interspike interval histograms showed that whereas ACh suppressed the spikes that occurred between bursts much more readily than those that occurred during bursts, all spikes were equally sensitive to the depressant action of GABA and glycine. Large doses of ACh provoked or exaggerated burst activity. 4. ACh-evoked inhibition was extremely sensitive to blockade by short iontophoretic applications of atropine, which had no effect on the inhibitions evoked on the same cell equipotent doses of GABA or glycine. The ACh-evoked inhibitions were also antagonized by dihydro-beta-erythroidine released with slightly larger currents. When tested on the same cell, small iontophoretic applications of picrotoxin and bicuculline methoiodide blocked the inhibition evoked by GABA but had no effect on that evoked by ACh. Iontophoretic strychnine only rarely affected the inhibition evoked by ACh, while readily blocking the inhibition evoked on the same cell by an equipotent dose of glycine. In two cats, intravenous strychnine (1-2 mg/kg) had no effect on the ACh-evoked inhibition, while greatly reducing the sensitivity of the cell under study to glycine. 5. Only four out of forty-eight ACh-inhibted cells tested were inhibited by iontophoretic applications of either guanosine or adenosine 3':5'-phosphate. 6. Cells of the nucleus reticularis have been shown to have an inhibitory action on the thalamic relay cells, which are excited by ACh. It is suggested that the presence of both ACh excited and inhibited cells in different nuclei of the thalamus could be of considerable functional significance in gating sensory transmission through the thalamus.

Hypothalamic digoxin, hemispheric chemical dominance, and eating behavior.

PubMed

Kurup, Ravi Kumar; Kurup, Parameswara Achutha

2003-08-01

The isoprenoid pathway produces an endogenous membrane Na+-K+ ATPase inhibitor, digoxin, which can regulate neurotransmitter and amino acid transport. Digoxin synthesis and neurotransmitter patterns were assessed in eating disorders. The patterns were compared in those with right hemispheric and left hemispheric dominance. The serum HMG CoA reductase activity, RBC membrane Na+-K+ ATPase activity, serum digoxin, magnesium, tryptophan catabolites (serotonin, quinolinic acid, strychnine, and nicotine), and tyrosine catabolites (morphine, dopamine, and noradrenaline) were measured in anorexia nervosa, bulimia nervosa, right hemispheric dominant, left hemispheric dominant, and bihemispheric dominant individuals. Digoxin synthesis was increased with upregulated tryptophan catabolism and downregulated tyrosine catabolism in those with anorexia nervosa and right hemispheric chemical dominance. Digoxin synthesis was reduced with downregulated tryptophan catabolism and upregulated tyrosine catabolism in those with bulimia nervosa and left hemispheric chemical dominance. The membrane Na+-K+ ATPase activity and serum magnesium were decreased in anorexia nervosa and right hemispheric chemical dominance while they were increased in bulimia nervosa and left hemispheric chemical dominance. Hypothalamic digoxin and hemispheric chemical dominance play a central role in the regulation of eating behavior. Anorexia nervosa represents the right hemispheric chemically dominant/hyperdigoxinemic state and bulimia nervosa the left hemispheric chemically dominant/hypodigoxinemic state.

Control of cutaneous leishmaniasis caused by Leishmania major in south-eastern Morocco.

PubMed

Bennis, Issam; De Brouwere, Vincent; Ameur, Btissam; El Idrissi Laamrani, Abderrahmane; Chichaoui, Smaine; Hamid, Sahibi; Boelaert, Marleen

2015-10-01

The incidence of cutaneous leishmaniasis (CL) caused by Leishmania major has increased in Morocco over the last decade, prompting the Ministry of Health to take intersectoral response measures including vector and reservoir control. The aim of this article was to describe the CL outbreak response measures taken in the province of Errachidia, where the reservoir of L. major, a sand rat (Meriones shawi), was targeted using strychnine-poisoned wheat baits from 2010 to 2012. We analysed routine surveillance data and other information using the data of the CL control programme. We present data on the evolution and the extension of CL in this province as well as the epidemiological profile of the disease. Between 2004 and 2013, 7099 cases of CL were recorded in Errachidia Province, gradually affecting all districts. Our results demonstrate that more women were affected than men and that all age groups were represented. Errachidia Province was the epicentre of the recent CL outbreak in Morocco. A notable decline in incidence rates was observed after 2011. The outbreak control measures may have contributed to this decline, as well as climatic trends or progressing herd immunity. © 2015 John Wiley & Sons Ltd.

In vitro pharmacologic characterization of a cholinergic receptor on outer hair cells.

PubMed

Erostegui, C; Norris, C H; Bobbin, R P

1994-04-01

Acetylcholine (ACh) is the major neurotransmitter released from the efferent fibers in the cochlea onto the outer hair cells (OHCs). The type of ACh receptor on OHCs and the events subsequent to receptor activation are unclear. Therefore we studied the effect of agonists and antagonists of the ACh receptor on isolated OHCs from the guinea pig. OHCs were recorded from in whole cell voltage and current clamp configuration. ACh induced an increase in outward K+ current (IACh) which hyperpolarized the OHCs. No desensitization to ACh application was observed. Cs+ replaced K+ in carrying the IACh. The IACh is Ca(2+)-dependent, time and voltage sensitive, and different from the IKCa induced by depolarization of the membrane potential. When tested at 100 microM, several agonists also induced outward current responses (acetylcholine > suberyldicholine > or = carbachol > DMPP) whereas nicotine, cytisine and muscarine did not. The IACh response to 10 microM ACh was blocked by low concentrations of traditional and non-traditional-nicotinic antagonists (strychnine > curare > bicuculline > alpha-bungarotoxin > thimethaphan) and by higher concentrations of muscarinic antagonists (atropine > 4-DAMP > AF-DX 116 > pirenzepine). Pharmacologically, the ACh receptor on OHCs is nicotinic.

[Machine Learning-based Prediction of Seizure-inducing Action as an Adverse Drug Effect].

PubMed

Gao, Mengxuan; Sato, Motoshige; Ikegaya, Yuji

2018-01-01

　During the preclinical research period of drug development, animal testing is widely used to help screen out a drug's dangerous side effects. However, it remains difficult to predict side effects within the central nervous system. Here, we introduce a machine learning-based in vitro system designed to detect seizure-inducing side effects before clinical trial. We recorded local field potentials from the CA1 alveus in acute mouse neocortico-hippocampal slices that were bath-perfused with each of 14 different drugs, and at 5 different concentrations of each drug. For each of these experimental conditions, we collected seizure-like neuronal activity and merged their waveforms as one graphic image, which was further converted into a feature vector using Caffe, an open framework for deep learning. In the space of the first two principal components, the support vector machine completely separated the vectors (i.e., doses of individual drugs) that induced seizure-like events, and identified diphenhydramine, enoxacin, strychnine and theophylline as "seizure-inducing" drugs, which have indeed been reported to induce seizures in clinical situations. Thus, this artificial intelligence-based classification may provide a new platform to pre-clinically detect seizure-inducing side effects of drugs.

Machine learning-based prediction of adverse drug effects: An example of seizure-inducing compounds.

PubMed

Gao, Mengxuan; Igata, Hideyoshi; Takeuchi, Aoi; Sato, Kaoru; Ikegaya, Yuji

2017-02-01

Various biological factors have been implicated in convulsive seizures, involving side effects of drugs. For the preclinical safety assessment of drug development, it is difficult to predict seizure-inducing side effects. Here, we introduced a machine learning-based in vitro system designed to detect seizure-inducing side effects. We recorded local field potentials from the CA1 alveus in acute mouse neocortico-hippocampal slices, while 14 drugs were bath-perfused at 5 different concentrations each. For each experimental condition, we collected seizure-like neuronal activity and merged their waveforms as one graphic image, which was further converted into a feature vector using Caffe, an open framework for deep learning. In the space of the first two principal components, the support vector machine completely separated the vectors (i.e., doses of individual drugs) that induced seizure-like events and identified diphenhydramine, enoxacin, strychnine and theophylline as "seizure-inducing" drugs, which indeed were reported to induce seizures in clinical situations. Thus, this artificial intelligence-based classification may provide a new platform to detect the seizure-inducing side effects of preclinical drugs. Copyright © 2017 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

Anticonvulsive activity of Butea monosperma flowers in laboratory animals.

PubMed

Kasture, Veena S; Kasture, S B; Chopde, C T

2002-07-01

The bioassay-guided fractionation of dried flowers of Butea monosperma (BM) was carried out to isolate the active principle responsible for its anticonvulsant activity. The petroleum ether extract was fractionated by column chromatography using solvents of varying polarity such as n-hexane, n-hexane:ethyl acetate, ethyl acetate, and methanol. The anticonvulsive principle of B. monosperma was found to be a triterpene (TBM) present in the n-hexane:ethyl acetate (1:1) fraction of the petroleum ether extract. TBM exhibited anticonvulsant activity against seizures induced by maximum electroshock (MES) and its PD(50) was found to be 34.2+/-18.1 mg/kg. TBM also inhibited seizures induced by pentylenetetrazol (PTZ), electrical kindling, and the combination of lithium sulfate and pilocarpine nitrate (Li-Pilo). However, TBM was not effective against seizures induced by strychnine and picrotoxin. TBM exhibited depressant effect on the central nervous system. After repeated use for 7 days, the PD(50) (MES) of TBM increased to 51.5+/-12.1 mg/kg. Similarly, after repeated use of TBM, the duration of sleep induced by pentobarbital was not reduced significantly. Further studies are required to investigate its usefulness in the treatment of epilepsy.

Evaluation of the calcium-antagonist, antidiarrhoeic and central nervous system activities of Baccharis serraefolia.

PubMed

Tortoriello, J; Aguilar-Santamaría, L

1996-09-01

Baccharis serraefolia is a widely used plant to treat diarrhoea in Mexican traditional medicine. Although the methanolic extract of this plant has shown an important dose-dependent spasmolytic activity, its underlying mechanism has not been studied. In the present work, the methanolic extract of B. serraefolia significantly delayed the onset of tonic seizures induced by strychnine and pentylenetetrazol; besides, it diminished the death rate and number of animals that exhibited convulsions. It produced potentiation of the hypnotic effect of pentobarbital. Oral administration produced an inhibition of gastrointestinal transit in mice as effective as that produced by loperamide. As to the effect on smooth muscles, the active extract produced an inhibition of contraction induced electrically, which could not be reversed by naloxone. The calcium concentration-contraction curve showed a rightward displacement when the extract was added to isolated guinea pig ileum depolarized with high K+ and cumulative concentrations of Ca2+. The results suggest that the methanolic extract does not interact with classical opiate receptors and its effects, at least that produced on smooth muscle, may be due to a probable interference with calcium influx and/or calcium release from an intra-cellular store.

Botany, Phytochemistry, Pharmacology and Toxicity of Strychnos nux-vomica L.: A Review.

PubMed

Guo, Rixin; Wang, Ting; Zhou, Guohong; Xu, Mengying; Yu, Xiankuo; Zhang, Xiao; Sui, Feng; Li, Chun; Tang, Liying; Wang, Zhuju

2018-01-01

Strychnos nux-vomica L. belongs to the genus Strychnos of the family Loganiaceae and grows in Sri Lanka, India and Australia. The traditional medicinal component is its seed, called Nux vomica. This study provides a relevant and comprehensive review of S. nux-vomica L., including its botany, ethnopharmacology, phytochemistry, pharmacology and toxicology, thus providing a foundation for future studies. Up to the present day, over 84 compounds, including alkaloids, iridoid glycosides, flavonoid glycosides, triterpenoids, steroids and organic acids, among others, have been isolated and identified from S. nux-vomica. These compounds possess an array of biological activities, including effects on the nervous system, analgesic and anti-inflammatory actions, antitumor effects, inhibition of the growth of pathogenic microorganisms and regulation of immune function. Furthermore, toxicity and detoxification methods are preliminarily discussed toward the end of this review. In further research on S. nux-vomica, bioactivity-guided isolation strategies should be emphasized. Its antitumor effects should be investigated further and in vivo animal experiments should be performed alongside in vitro testing. The pharmacological activity and toxicology of strychnine [Formula: see text]-oxide and brucine [Formula: see text]-oxide should be studied to explore the detoxification mechanism associated with processing more deeply.

Taurine activates delayed rectifier KV channels via a metabotropic pathway in retinal neurons

PubMed Central

Bulley, Simon; Liu, Yufei; Ripps, Harris; Shen, Wen

2013-01-01

Taurine is one of the most abundant amino acids in the retina, throughout the CNS, and in heart and muscle cells. In keeping with its broad tissue distribution, taurine serves as a modulator of numerous basic processes, such as enzyme activity, cell development, myocardial function and cytoprotection. Despite this multitude of functional roles, the precise mechanism underlying taurine's actions has not yet been identified. In this study we report findings that indicate a novel role for taurine in the regulation of voltage-gated delayed rectifier potassium (KV) channels in retinal neurons by means of a metabotropic receptor pathway. The metabotropic taurine response was insensitive to the Cl− channel blockers, picrotoxin and strychnine, but it was inhibited by a specific serotonin 5-HT2A receptor antagonist, MDL11939. Moreover, we found that taurine enhanced KV channels via intracellular protein kinase C-mediated pathways. When 5-HT2A receptors were expressed in human embryonic kidney cells, taurine and AL34662, a non-specific 5-HT2 receptor activator, produced a similar regulation of KIR channels. In sum, this study provides new evidence that taurine activates a serotonin system, apparently via 5-HT2A receptors and related intracellular pathways. PMID:23045337

Extrasynaptic localization of glycine receptors in the rat supraoptic nucleus: further evidence for their involvement in glia-to-neuron communication.

PubMed

Deleuze, C; Alonso, G; Lefevre, I A; Duvoid-Guillou, A; Hussy, N

2005-01-01

Neurons of the rat supraoptic nucleus (SON) express glycine receptors (GlyRs), which are implicated in the osmoregulation of neuronal activity. The endogenous agonist of the receptors has been postulated to be taurine, shown to be released from astrocytes. We here provide additional pieces of evidence supporting the absence of functional glycinergic synapses in the SON. First, we show that blockade of GlyRs with strychnine has no effect on either the amplitude or frequency of miniature inhibitory postsynaptic currents recorded in SON neurons, whereas they were all suppressed by the GABA(A) antagonist gabazine. Then, double immunostaining of sections with presynaptic markers and either GlyR or GABA(A) receptor (GABA(A)R) antibodies indicates that, in contrast with GABA(A)Rs, most GlyR membrane clusters are not localized facing presynaptic terminals, indicative of their extrasynaptic localization. Moreover, we found a striking anatomical association between SON GlyR clusters and glial fibrillary acidic protein (GFAP)-positive astroglial processes, which contain high levels of taurine. This type of correlation is specific to GlyRs, since GABA(A)R clusters show no association with GFAP-positive structures. These results substantiate and strengthen the concept of extrasynaptic GlyRs mediating a paracrine communication between astrocytes and neurons in the SON.

Rhythmic motor activity and interlimb co-ordination in the developing pouch young of a wallaby (Macropus eugenii).

PubMed Central

Ho, S M

1997-01-01

1. The forelimb motor behaviour of developing wallaby was studied. A clock-like alternating movement was reactivated whenever the animal was removed from the pouch. 2. Forelimb stepping frequency increased during the first 3 weeks of development, while the phase relationship remained constant. Forelimb activity could be affected by altering the afferent feedback from the contralateral limb, or an increase in ambient temperature. 3. In vitro experiments were performed using an isolated brainstem-spinal cord preparation from animals up to 6 weeks postnatal. Fictive locomotor activity could be evoked by electrical stimulation or bath-applied NMDA (< 10 microM). 4. Bath-applied strychnine (10-25 microM) and bicuculline (10-50 microM) disrupted the phase relationship between motor pools, while rhythmic motor discharge remained in the absence of these inhibitory pathways. 5. The present findings indicate that the pattern generator that underlies the robust forelimb movement during the first journey to the pouch is retained for different motor functions during in-pouch development. The neural network that underlies such behaviour can be divided into two major components, a rhythm generator within each hemicord, and a pattern co-ordinating pathway which involve both glycinergic and GABAergic interneurones. PMID:9218221

In vivo myosin step-size from zebrafish skeletal muscle

PubMed Central

Ajtai, Katalin; Sun, Xiaojing; Takubo, Naoko; Wang, Yihua

2016-01-01

Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the ‘bottom-up’ myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation. Macroscopic muscle physiological experimentation provides the definitive ‘top-down’ phenotype characterizations that are the concerns in translational medicine. In vivo single myosin detection in muscle from zebrafish embryo models for human muscle fulfils ambitions for both bottom-up and top-down experimentation. A photoactivatable green fluorescent protein (GFP)-tagged myosin light chain expressed in transgenic zebrafish skeletal muscle specifically modifies the myosin lever-arm. Strychnine induces the simultaneous contraction of the bilateral tail muscles in a live embryo, causing them to be isometric while active. Highly inclined thin illumination excites the GFP tag of single lever-arms and its super-resolution orientation is measured from an active isometric muscle over a time sequence covering many transduction cycles. Consecutive frame lever-arm angular displacement converts to step-size by its product with the estimated lever-arm length. About 17% of the active myosin steps that fall between 2 and 7 nm are implicated as powerstrokes because they are beyond displacements detected from either relaxed or ATP-depleted (rigor) muscle. PMID:27249818

4-dimensional functional profiling in the convulsant-treated larval zebrafish brain.

PubMed

Winter, Matthew J; Windell, Dylan; Metz, Jeremy; Matthews, Peter; Pinion, Joe; Brown, Jonathan T; Hetheridge, Malcolm J; Ball, Jonathan S; Owen, Stewart F; Redfern, Will S; Moger, Julian; Randall, Andrew D; Tyler, Charles R

2017-07-26

Functional neuroimaging, using genetically-encoded Ca 2+ sensors in larval zebrafish, offers a powerful combination of high spatiotemporal resolution and higher vertebrate relevance for quantitative neuropharmacological profiling. Here we use zebrafish larvae with pan-neuronal expression of GCaMP6s, combined with light sheet microscopy and a novel image processing pipeline, for the 4D profiling of chemoconvulsant action in multiple brain regions. In untreated larvae, regions associated with autonomic functionality, sensory processing and stress-responsiveness, consistently exhibited elevated spontaneous activity. The application of drugs targeting different convulsant mechanisms (4-Aminopyridine, Pentylenetetrazole, Pilocarpine and Strychnine) resulted in distinct spatiotemporal patterns of activity. These activity patterns showed some interesting parallels with what is known of the distribution of their respective molecular targets, but crucially also revealed system-wide neural circuit responses to stimulation or suppression. Drug concentration-response curves of neural activity were identified in a number of anatomically-defined zebrafish brain regions, and in vivo larval electrophysiology, also conducted in 4dpf larvae, provided additional measures of neural activity. Our quantification of network-wide chemoconvulsant drug activity in the whole zebrafish brain illustrates the power of this approach for neuropharmacological profiling in applications ranging from accelerating studies of drug safety and efficacy, to identifying pharmacologically-altered networks in zebrafish models of human neurological disorders.

THE PROPHYLAXIS OF RADIATION AFFLICTIONS WITH THE HELP OF COMBINATION OF MEDICINAL AGENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiunov, L.A.

1960-01-01

The Western and Soviet literature on the use of mixtures of various agents for protection sgainst radiation ailments is reviewed. Good results were obtained with a combination of cysteine and potassium cyanide. It was found that the resistance of animals to radiation sickness increases markedly after acclimatization to hypoxia. The resistance to radiation of such acclimatized mice could be further increased by injecting them before irradiation with cysteamine or cystamine. Cysteine was successfully injected into rats that had received citrine for 30 days previously. These animals proved more resistant to radiation than rats which received only cysteine. Successful use wasmore » made of adrenalin and acetyl choline, cysteamine and cystisine, cysteamine and adenosin, triphosphoric acid, cysteine, tryptamine and protamine, sodium nitrite and ethyl alcohol, mixtures of phenatin and its derivatives with mercamine, chlorpromazine with S-aminoethylisothiuronium, aminasine or mepasine with phenatin were used. It was noted that the combined use of adrenocorticotropic hormone and cysteine, far from boosting the prophylactic effect of cysteine, actually led to deterioration of the animals' condition. Other unsuccessful combinations were: cysteamine and strychnine, cysteamine and ginseng, and cysteamine and cholinolytics. It was concluded that effective antiradiation prescriptions can be developed by combining typical sulfhydryl prophylactic agents. (OTS)« less

Śodhana: An Ayurvedic process for detoxification and modification of therapeutic activities of poisonous medicinal plants

PubMed Central

Maurya, Santosh Kumar; Seth, Ankit; Laloo, Damiki; Singh, Narendra Kumar; Gautam, Dev Nath Singh; Singh, Anil Kumar

2015-01-01

Ayurveda involves the use of drugs obtained from plants, animals, and mineral origin. All the three sources of drugs can be divided under poisonous and nonpoisonous category. There are various crude drugs, which generally possess unwanted impurities and toxic substances, which can lead to harmful health problems. Many authors have reported that not all medicinal plants are safe to use since they can bear many toxic and harmful phytoconstituents in them. Śodhana (detoxification/purification) is the process, which involves the conversion of any poisonous drug into beneficial, nonpoisonous/nontoxic ones. Vatsanābha (Aconitum species), Semecarpus anacardium, Strychnos nux-vomica, Acorus calamus, Abrus precatorius etc., are some of the interesting examples of toxic plants, which are still used in the Indian system of medicine. Aconite, bhilawanols, strychnine, β–asarone, abrin are some of the toxic components present in these plants and are relatively toxic in nature. Śodhana process involves the purification as well as reduction in the levels of toxic principles which sometimes results in an enhanced therapeutic efficacy. The present review is designed to extensively discuss and understand the scientific basis of the alternative use of toxic plants as a medicine after their purification process. PMID:26283803

Soa genotype selectively affects mouse gustatory neural responses to sucrose octaacetate

PubMed Central

INOUE, MASASHI; LI, XIA; McCAUGHEY, STUART A.; BEAUCHAMP, GARY K.; BACHMANOV, ALEXANDER A.

2013-01-01

In mice, behavioral acceptance of the bitter compound sucrose octaacetate (SOA) depends on allelic variation of a single gene, Soa. The SW.B6-Soab congenic mouse strain has the genetic background of an “SOA taster” SWR/J strain and an Soa-containing donor chromosome fragment from an “SOA nontaster” C57BL/6J strain. Using microsatellite markers polymorphic between the two parental strains, we determined that the donor fragment spans 5–10 cM of distal chromosome 6. The SWR/J mice avoided SOA in two-bottle tests with water and had strong responses to SOA in two gustatory nerves, the chorda tympani (CT) and glossopharyngeal (GL). In contrast, the SW.B6-Soab mice were indifferent to SOA in two-bottle tests and had very weak responses to SOA in both of these nerves. The SWR/J and SW.B6-Soab mice did not differ in responses of either nerve to sucrose, NaCl, HCl, or the bitter-tasting stimuli quinine, denatonium, strychnine, 6-n-propylthiouracil, phenylthiocarbamide, and MgSO4. Thus the effect of the Soa genotype on SOA avoidance is mediated by peripheral taste responsiveness to SOA, involving taste receptor cells innervated by both the CT and GL nerves. PMID:11328963

Evaluation of Behavioral and Pharmacological Effects of Hydroalcoholic Extract of Valeriana prionophylla Standl. from Guatemala

PubMed Central

Holzmann, Iandra; Cechinel Filho, Valdir; Mora, Ticiana C.; Cáceres, Armando; Martínez, Jose Vicente; Cruz, Sully M.; de Souza, Márcia Maria

2011-01-01

There are few studies on the pharmacological properties of Valeriana prionophylla Standl. (VP), known as “Valeriana del monte”, and used in Mesoamerican folk medicine to treat sleep disorders. This study examines the pharmacological effects of the hydroalcoholic extract of the dry rhizome using the open field, rota rod, elevated plus-maze (EPM), forced swimming (FST), strychnine- and pentobarbital-induced sleeping time, PTZ-induced seizures, and the inhibitory avoidance tests. VP did not show any protective effect against PTZ-induced convulsions. In the EPM, exhibited an anxiolytic-like effect through the effective enhancement of the entries (38.5%) and time spent (44.7%) in the open arms, when compared with control group. Time spent and the numbers of entrances into the enclosed arms were decreased, similar to those effects observed with diazepam. In the FST, acute treatment with VP, produced a dose-dependent decrease in immobility time, similarly to imipramine. VP also produced a significant dose-dependent decrease in the latency of sleeping time, while producing an increase in total duration of sleep; influenced memory consolidation of the animals only at lower doses, unlike those that produced anti-depressant and anxiolytic effects. In summary, the results suggest that VP presents several psychopharmacological activities, including anxiolytic, antidepressant, and hypno-sedative effects. PMID:21754942

Two antagonistic gustatory receptor neurons responding to sweet-salty and bitter taste in Drosophila.

PubMed

Hiroi, Makoto; Meunier, Nicolas; Marion-Poll, Frédéric; Tanimura, Teiichi

2004-12-01

In Drosophila, gustatory receptor neurons (GRNs) occur within hair-like structures called sensilla. Most taste sensilla house four GRNs, which have been named according to their preferred sensitivity to basic stimuli: water (W cell), sugars (S cell), salt at low concentration (L1 cell), and salt at high concentration (L2 cell). Labellar taste sensilla are classified into three types, l-, s-, and i-type, according to their length and location. Of these, l- and s-type labellar sensilla possess these four cells, but most i-type sensilla house only two GRNs. In i-type sensilla, we demonstrate here that the first GRN responds to sugar and to low concentrations of salt (10-50 mM NaCl). The second GRN detects a range of bitter compounds, among which strychnine is the most potent; and also to salt at high concentrations (over 400 mM NaCl). Neither type of GRN responds to water. The detection of feeding stimulants in i-type sensilla appears to be performed by one GRN with the combined properties of S+L1 cells, while the other GRN detects feeding inhibitors in a similar manner to bitter-sensitive L2 cells on the legs. These sensilla thus house two GRNs having an antagonistic effect on behavior, suggesting that the expression of taste receptors is segregated across them accordingly. copyright (c) 2004 Wiley Periodicals, Inc.

HSQC-1,n-ADEQUATE: a new approach to long-range 13C-13C correlation by covariance processing.

PubMed

Martin, Gary E; Hilton, Bruce D; Willcott, M Robert; Blinov, Kirill A

2011-10-01

Long-range, two-dimensional heteronuclear shift correlation NMR methods play a pivotal role in the assembly of novel molecular structures. The well-established GHMBC method is a high-sensitivity mainstay technique, affording connectivity information via (n)J(CH) coupling pathways. Unfortunately, there is no simple way of determining the value of n and hence no way of differentiating two-bond from three- and occasionally four-bond correlations. Three-bond correlations, however, generally predominate. Recent work has shown that the unsymmetrical indirect covariance or generalized indirect covariance processing of multiplicity edited GHSQC and 1,1-ADEQUATE spectra provides high-sensitivity access to a (13)C-(13) C connectivity map in the form of an HSQC-1,1-ADEQUATE spectrum. Covariance processing of these data allows the 1,1-ADEQUATE connectivity information to be exploited with the inherent sensitivity of the GHSQC spectrum rather than the intrinsically lower sensitivity of the 1,1-ADEQUATE spectrum itself. Data acquisition times and/or sample size can be substantially reduced when covariance processing is to be employed. In an extension of that work, 1,n-ADEQUATE spectra can likewise be subjected to covariance processing to afford high-sensitivity access to the equivalent of (4)J(CH) GHMBC connectivity information. The method is illustrated using strychnine as a model compound. Copyright © 2011 John Wiley & Sons, Ltd.

Toward the characterization of biological toxins using field-based FT-IR spectroscopic instrumentation

NASA Astrophysics Data System (ADS)

Schiering, David W.; Walton, Robert B.; Brown, Christopher W.; Norman, Mark L.; Brewer, Joseph; Scott, James

2004-12-01

IR spectroscopy is a broadly applicable technique for the identification of covalent materials. Recent advances in instrumentation have made Fourier Transform infrared (FT-IR) spectroscopy available for field characterization of suspect materials. Presently, this instrumentation is broadly deployed and used for the identification of potential chemical hazards. This discussion concerns work towards expanding the analytical utility of field-based FT-IR spectrometry in the characterization of biological threats. Two classes of materials were studied: biologically produced chemical toxins which were non-peptide in nature and peptide toxin. The IR spectroscopic identification of aflatoxin-B1, trichothecene T2 mycotoxin, and strychnine was evaluated using the approach of spectral searching against large libraries of materials. For pure components, the IR method discriminated the above toxins at better than the 99% confidence level. The ability to identify non-peptide toxins in mixtures was also evaluated using a "spectral stripping" search approach. For the mixtures evaluated, this method was able to identify the mixture components from ca. 32K spectral library entries. Castor bean extract containing ricin was used as a representative peptide toxin. Due to similarity in protein spectra, a SIMCA pattern recognition methodology was evaluated for classifying peptide toxins. In addition to castor bean extract the method was validated using bovine serum albumin and myoglobin as simulants. The SIMCA approach was successful in correctly classifying these samples at the 95% confidence level.

Time-dependent expression of hypertonic effects on bullfrog taste nerve responses to salts and bitter substances.

PubMed

Mashiyama, Kazunori; Nozawa, Yuhei; Ohtubo, Yoshitaka; Kumazawa, Takashi; Yoshii, Kiyonori

2014-03-27

We previously showed that the hypertonicity of taste stimulating solutions modified tonic responses, the quasi-steady state component following the transient (phasic) component of each integrated taste nerve response. Here we show that the hypertonicity opens tight junctions surrounding taste receptor cells in a time-dependent manner and modifies whole taste nerve responses in bullfrogs. We increased the tonicity of stimulating solutions with non-taste substances such as urea or ethylene glycol. The hypertonicity enhanced phasic responses to NaCl>0.2M, and suppressed those to NaCl<0.1M, 1mM CaCl2, and 1mM bitter substances (quinine, denatonium and strychnine). The hypertonicity also enhanced the phasic responses to a variety of 0.5M salts such as LiCl and KCl. The enhancing effect was increased by increasing the difference between the ionic mobilities of the cations and anions in the salt. A preincubation time >20s in the presence of 1M non-taste substances was needed to elicit both the enhancing and suppressing effects. Lucifer Yellow CH, a paracellular marker dye, diffused into bullfrog taste receptor organs in 30s in the presence of hypertonicity. These results agreed with our proposed mechanism of hypertonic effects that considered the diffusion potential across open tight junctions. Copyright © 2014 Elsevier B.V. All rights reserved.

The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

NASA Astrophysics Data System (ADS)

Nicholson, John W.; Wilson, Alan

2004-09-01

This article describes the history of the reaction converting carboxylic acids to ketones. The reaction has been rediscovered several times, yet has actually been known for centuries. The best known version of the process is the Dakin West reaction (1928), which applies to α-amino acids and also involves the simultaneous conversion of the amine group to amido functionality. Unlike other examples, this particular reaction has attracted a reasonable amount of attention and it appears to be better known than the conversion of simple carboxylic acids to ketones. However, this reaction was described as long ago as 1612, when Beguin published an account of it in his book, Tyrocinium Chymicum . Since then, many chemists have rediscovered the reaction, apparently independently. One of the earliest modern accounts was by W. H. Perkin, Sr., in 1886, who made various simple ketones by refluxing the appropriate carboxylic acids with base. However, this work has been largely ignored, including by his son, W. H. Perkin, Jr., who used a more complicated base-catalyzed ketonization to prepare small ring compounds in the early years of the 20th century. Other articles detailing the application of ketonization to organic acids are discussed, including our own work, which employed the process to crosslink carboxylated polymers for possible technical application in coatings. Despite its relative obscurity, the reaction was used by Woodward et al. in the total synthesis of strychnine, reported in 1963, and this is discussed in detail at the end of the article. See Featured Molecules .

Determination of phytochemicals, antioxidant activity and total phenolic content in Andrographis paniculata using chromatographic methods.

PubMed

Kurzawa, Marzanna; Filipiak-Szok, Anna; Kłodzińska, Ewa; Szłyk, Edward

2015-07-15

Antioxidant activity, total phenolics content and selected phytochemicals (alkaloids and andrographolides) were determined in Andrographis paniculata and in dietary supplements containing this plant. Antioxidant activity was measured by FRAP, CUPRAC and DPPH procedures and ranged from 503.36 to 6164.09μmol TE/100g d.m. depending on methods, part of plant and kind of dietary supplement. The total phenolics (175.13-1723.79mg GAE/100g) and andrographolides content (19.44-85.13mg/g) in the studied samples were correlated with antioxidant activities determined by CUPRAC, FRAP and DPPH (r>0.95, p<0.05 level). Purine alkaloids: caffeine, theobromine, theophylline and indole alkaloids: harmine, harmane, harmol, yohimbine, brucine and strychnine were detected in the studied samples by different chromatographic techniques (HPLC-DAD, LC-MS/MS, GC-MS). The total alkaloids content in APs-roots and APs-leaves varies from 50.71±0.36mg/g d.m. to 78.71±0.48mg/g d.m., respectively, whereas for dietary supplements (Pn and DK) TAC was found between 19.52±0.15mg/g and 22.18±0.15mg/g d.m.. The highest concentration of andrographolides was found in A. paniculata leaves, whereas the lowest in dietary supplement Pn. Moreover principal component analysis, cluster analysis and one-way ANOVA follow by Duncan's tests were also performed. Copyright © 2015. Published by Elsevier B.V.

Effects of pesticides on owls in North America

USGS Publications Warehouse

Blus, L.J.

1996-01-01

A literature review of the effects of pesticides on owls in North America showed that relatively few studies have been undertaken. Owls used in experiments seem as sensitive to organochlorine pesticides (OCs) as other birds of prey, but wild owls experienced few serious problems, primarily because they were exposed to lower residues in their predominately mammalian or invertebrate prey. For example, the great horned owl ( Bubo virginianus ) and the common barn-owl ( Tyto alba ) neither experienced marked changes in mortality or recruitment rates nor was there any evidence of population decreases even during the maximum period of OC pesticide use. Also, eggshell thinning was not a widespread problem. There were adverse effects on individual owls including verified records of 74 owls of six species that died from secondary or tertiary poisoning related to strychnine, organochlorines, anticholinesterases (antiChEs) and anticoagulants in 16 states within the U.S. and one province in Canada. Most of the pesticide-related deaths occurred during the 1980s, although this probably does not represent a true temporal distribution. Verified mortalities of owls probably represent a small fraction of the actual number that died from pesticides. Incidence of mortality seems biased geographically toward areas such as New York that have active ecotoxicological programs. Burrowing owl ( Speotyto cunicularia ) populations currently are decreasing throughout much of the range in the U.S. and Canada. Studies in Canada indicate that antiChE pesticides, particularly carbofuran, were responsible for the declines there.

The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus.

PubMed

Kawai, Nobuhiro; Sakai, Noriaki; Okuro, Masashi; Karakawa, Sachie; Tsuneyoshi, Yosuke; Kawasaki, Noriko; Takeda, Tomoko; Bannai, Makoto; Nishino, Seiji

2015-05-01

The use of glycine as a therapeutic option for improving sleep quality is a novel and safe approach. However, despite clinical evidence of its efficacy, the details of its mechanism remain poorly understood. In this study, we investigated the site of action and sleep-promoting mechanisms of glycine in rats. In acute sleep disturbance, oral administration of glycine-induced non-rapid eye movement (REM) sleep and shortened NREM sleep latency with a simultaneous decrease in core temperature. Oral and intracerebroventricular injection of glycine elevated cutaneous blood flow (CBF) at the plantar surface in a dose-dependent manner, resulting in heat loss. Pretreatment with N-methyl-D-aspartate (NMDA) receptor antagonists AP5 and CGP78608 but not the glycine receptor antagonist strychnine inhibited the CBF increase caused by glycine injection into the brain. Induction of c-Fos expression was observed in the hypothalamic nuclei, including the medial preoptic area (MPO) and the suprachiasmatic nucleus (SCN) shell after glycine administration. Bilateral microinjection of glycine into the SCN elevated CBF in a dose-dependent manner, whereas no effect was observed when glycine was injected into the MPO and dorsal subparaventricular zone. In addition, microinjection of D-serine into the SCN also increased CBF, whereas these effects were blocked in the presence of L-701324. SCN ablation completely abolished the sleep-promoting and hypothermic effects of glycine. These data suggest that exogenous glycine promotes sleep via peripheral vasodilatation through the activation of NMDA receptors in the SCN shell.

Effects of D-cycloserine on extinction and reinstatement of morphine-induced conditioned place preference.

PubMed

Lu, Guan-Yi; Wu, Ning; Zhang, Zhao-Long; Ai, Jing; Li, Jin

2011-10-10

d-Cycloserine (DCS), a partial agonist at the strychnine-insensitive glycine recognition site on the N-methyl-d-aspartate (NMDA) receptor complex, has been shown to facilitate the extinction and prevent the relapse of cocaine-induced conditioned place preference (CPP) when administered before or after each extinction trail. However, some studies have suggested that DCS does not influence or even enhance relapse of seeking behavior on cocaine self-administration (SA) in rats or cocaine-dependent individuals undergoing clinical exposure treatment. Furthermore, there are no reports on the effects of DCS and the extinction of morphine-conditioned behaviors in mice. The present study investigated the effects of DCS on extinction by exposing mice to drug-paired cues and the subsequent reinstatement of morphine-primed CPP. Our results showed that DCS at doses of 7.5, 15, and 30mg/kg did not induce conditioned appetitive or aversive effects and DCS combined with morphine conditioning failed to affect the acquisition of morphine-induced CPP. Moreover, pretreatment with DCS (7.5, 15, and 30mg/kg, i.p.) prior to extinction training had no significant effects on the extinction and subsequent morphine-primed reinstatement of morphine-induced CPP. These results suggested that DCS may not be a powerful adjunct for cue exposure therapy of opioid addiction. In view of differing outcomes in both preclinical and clinical studies, the potential of DCS in exposure treatment of drug-seeking behaviors should be carefully evaluated. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Regional modulation of the response to glutathione in Hydra vulgaris.

PubMed

Pierobon, Paola

2015-07-01

In the presence of prey, or upon exposure to reduced glutathione (GSH), Hydra polyps open a mouth to ingest the captured prey and close it after feeding; at rest the mouth is not evident. In previous papers we have shown that GABA, glycine and NMDA modulate the mechanisms of mouth closure through ligand-gated-ion-channel receptors that are similar to their mammalian analogues in terms of biochemical and pharmacological properties. In order to study the regional distribution of these receptors, we have applied the GSH assay to polyps amputated at different levels of the body column. The response to 1-10 µmol l(-1) GSH of polyps lacking either peduncle and foot or the entire body columns (heads) was not different from control, whole animals. In the presence of GABA or muscimol, duration of the response was significantly decreased in heads; the decrease was suppressed by the GABA antagonists gabazine and bicuculline. By contrast, in animals lacking peduncle and foot, duration of the response did not vary upon GABA administration. Conversely, in the presence of glycine, duration of the response in heads preparations was similar to control, whereas in footless polyps, it was significantly reduced. The decrease was mimicked by the glycine agonists taurine and β-alanine, and counteracted by strychnine. These results suggest a regional distribution of receptors to GABA and glycine in the neuromuscular circuitry modulating the feeding behaviour. © 2015. Published by The Company of Biologists Ltd.

Role of Parafacial Nuclei in Control of Breathing in Adult Rats

PubMed Central

Huckstepp, Robert T.R.; Cardoza, Kathryn P.; Henderson, Lauren E.

2015-01-01

Contiguous brain regions associated with a given behavior are increasingly being divided into subregions associated with distinct aspects of that behavior. Using recently developed neuronal hyperpolarizing technologies, we functionally dissect the parafacial region in the medulla, which contains key elements of the central pattern generator for breathing that are important in central CO2-chemoreception and for gating active expiration. By transfecting different populations of neighboring neurons with allatostatin or HM4D Gi/o-coupled receptors, we analyzed the effect of their hyperpolarization on respiration in spontaneously breathing vagotomized urethane-anesthetized rats. We identify two functionally separate parafacial nuclei: ventral (pFV) and lateral (pFL). Disinhibition of the pFL with bicuculline and strychnine led to active expiration. Hyperpolarizing pFL neurons had no effect on breathing at rest, or changes in inspiratory activity induced by hypoxia and hypercapnia; however, hyperpolarizing pFL neurons attenuated active expiration when it was induced by hypercapnia, hypoxia, or disinhibition of the pFL. In contrast, hyperpolarizing pFV neurons affected breathing at rest by decreasing inspiratory-related activity, attenuating the hypoxia- and hypercapnia-induced increase in inspiratory activity, and when present, reducing expiratory-related abdominal activity. Together with previous observations, we conclude that the pFV provides a generic excitatory drive to breathe, even at rest, whereas the pFL is a conditional oscillator quiet at rest that, when activated, e.g., during exercise, drives active expiration. PMID:25609622

Forensic toxicology analysis of self-poisoning suicidal deaths in Tehran, Iran; trends between 2011-2015.

PubMed

Kordrostami, Roya; Akhgari, Maryam; Ameri, Maryam; Ghadipasha, Masoud; Aghakhani, Kamran

2017-06-13

Suicide ranks among the top ten causes of death in all age groups all over the world. There are many methods for committing suicide including self-poisoning, firearm and hanging. The aim of the present study was to provide an overview of self-poisoning related suicidal deaths with special focus on forensic toxicology analysis results in Tehran, Iran from 2011 to 2015. All suspicious cases with the the history of self-poisoning were investigated to define the cause and manner of death under the supervision of forensic medicine practitioners. Postmortem samples were analysed in forensic toxicology laboratory to confirm the presence of drugs in cadaver of suicidal cases. Drugs and poisons were analysed using thin layer chromatography, high performance liquid chromatography, gas chromatography/mass spectrometry, headspace gas chromatography and gas chromatography equipped with nitrogen phosphorus detector. Demographic data were collected from autopsy reports of all cases with confirmed self-poisoning suicidal cause of death. Results showed that 674 cases of self-poisoning deaths were investigated during a five-year study period, of which 68.55% were male. The most often used suicide method was self-poisoning in young population. Phosphine gas liberated from aluminum phosphide tablets was the most toxic substance detected in postmortem samples (619 cases) followed by opioids, methamphetamine, organophosphates, cyanide and strychnine. In conclusion self-poisoning suicidal death was predominant in young male population in Tehran, Iran. It seems that free access to suicide means such as drugs and poisons should be restricted by national and health authorities. Not applicable.

Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons

PubMed Central

Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Hirata, Hiromi; Moorhouse, Andrew J.; Ishibashi, Hitoshi

2017-01-01

Abstract Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system. PMID:28197549

Contralateral-noise effects on cochlear responses in anesthetized mice are dominated by feedback from an unknown pathway

PubMed Central

Usubuchi, Hajime; Vetter, Douglas E.; Elgoyhen, A. Bélen; Thomas, Steven A.; Liberman, M. Charles

2012-01-01

Suppression of ipsilateral distortion product otoacoustic emissions (DPOAEs) by contralateral noise is used in humans and animals to assay the strength of sound-evoked negative feedback from the medial olivocochlear (MOC) efferent pathway. However, depending on species and anesthesia, contributions of other feedback systems to the middle or inner ear can cloud the interpretation. Here, contributions of MOC and middle-ear muscle reflexes, as well as autonomic feedback, to contra-noise suppression in anesthetized mice are dissected by selectively eliminating each pathway by surgical transection, pharmacological blockade, or targeted gene deletion. When ipsilateral DPOAEs were evoked by low-level primaries, contra-noise suppression was typically ∼1 dB with contra-noise levels around 95 dB SPL, and it always disappeared upon contralateral cochlear destruction. Lack of middle-ear muscle contribution was suggested by persistence of contra-noise suppression after paralysis with curare, tensor tympani cauterization, or section of the facial nerve. Contribution of cochlear sympathetics was ruled out by studying mutant mice lacking adrenergic signaling (dopamine β-hydroxylase knockouts). Surprisingly, contra-noise effects on low-level DPOAEs were also not diminished by eliminating the MOC system pharmacologically (strychnine), surgically, or by deletion of relevant cholinergic receptors (α9/α10). In contrast, when ipsilateral DPOAEs were evoked by high-level primaries, the contra-noise suppression, although comparable in magnitude, was largely eliminated by MOC blockade or section. Possible alternate pathways are discussed for the source of contra-noise-evoked effects at low ipsilateral levels. PMID:22514298

Lack of the alanine-serine-cysteine transporter 1 causes tremors, seizures, and early postnatal death in mice.

PubMed

Xie, Xinmin; Dumas, Theodore; Tang, Lamont; Brennan, Thomas; Reeder, Thadd; Thomas, Winston; Klein, Robert D; Flores, Judith; O'Hara, Bruce F; Heller, H Craig; Franken, Paul

2005-08-09

The Na(+)-independent alanine-serine-cysteine transporter 1 (Asc-1) is exclusively expressed in neuronal structures throughout the central nervous system (CNS). Asc-1 transports small neutral amino acids with high affinity especially for D-serine and glycine (K(i): 8-12 microM), two endogenous glutamate co-agonists that activate N-methyl-D-aspartate (NMDA) receptors through interacting with the strychnine-insensitive glycine binding-site. By regulating D-serine (and possibly glycine) levels in the synaptic cleft, Asc-1 may play an important role in controlling neuronal excitability. We generated asc-1 gene knockout (asc-1(-/-)) mice to test this hypothesis. Behavioral phenotyping combined with electroencephalogram (EEG) recordings revealed that asc-1(-/-) mice developed tremors, ataxia, and seizures that resulted in early postnatal death. Both tremors and seizures were reduced by the NMDA receptor antagonist MK-801. Extracellular recordings from asc-1(-/-) brain slices indicated that the spontaneous seizure activity did not originate in the hippocampus, although, in this region, a relative increase in evoked synaptic responses was observed under nominal Mg(2+)-free conditions. Taken together with the known neurochemistry and neuronal distribution of the Asc-1 transporter, these results indicate that the mechanism underlying the behavioral hyperexcitability in mutant mice is likely due to overactivation of NMDA receptors, presumably resulting from elevated extracellular D-serine. Our study provides the first evidence to support the notion that Asc-1 transporter plays a critical role in regulating neuronal excitability, and indicate that the transporter is vital for normal CNS function and essential to postnatal survival of mice.

Reciprocal regulation between taurine and glutamate response via Ca2+- dependent pathways in retinal third-order neurons

PubMed Central

2010-01-01

Although taurine and glutamate are the most abundant amino acids conducting neural signals in the central nervous system, the communication between these two neurotransmitters is largely unknown. This study explores the interaction of taurine and glutamate in the retinal third-order neurons. Using specific antibodies, both taurine and taurine transporters were localized in photoreceptors and Off-bipolar cells, glutamatergic neurons in retinas. It is possible that Off-bipolar cells release juxtaposed glutamate and taurine to activate the third-order neurons in retina. The interaction of taurine and glutamate was studied in acutely dissociated third-order neurons in whole-cell patch-clamp recording and Ca2+ imaging. We find that taurine effectively reduces glutamate-induced Ca2+ influx via ionotropic glutamate receptors and voltage-dependent Ca2+ channels in the neurons, and the effect of taurine was selectively inhibited by strychnine and picrotoxin, but not GABA receptor antagonists, although GABA receptors are present in the neurons. A CaMKII inhibitor partially reversed the effect of taurine, suggesting that a Ca2+/calmodulin-dependent pathway is involved in taurine regulation. On the other hand, a rapid influx of Ca2+ through ionotropic glutamate receptors could inhibit the amplitude and kinetics of taurine-elicited currents in the third-order neurons, which could be controlled with intracellular application of BAPTA a fast Ca2+ chelator. This study indicates that taurine is a potential neuromodulator in glutamate transmission. The reciprocal inhibition between taurine and glutamate in the postsynaptic neurons contributes to computation of visual signals in the retinal neurons. PMID:20804625

Beneficial effects of glycine (bioglycin) on memory and attention in young and middle-aged adults.

PubMed

File, S E; Fluck, E; Fernandes, C

1999-12-01

The N-methyl D-aspartate receptor complex is involved in the mechanism of long-term potentiation, which is thought to be the biological basis of learning and memory. This complex can be manipulated in a number of ways, one of which is through the strychnine-insensitive glycine receptor coagonist site. The effects of Bioglycin(Konapharma, Pratteln, Switzerland), a biologically active form of the amino acid glycine, were therefore studied in healthy students (mean age, 20.7 years) and middle-aged men (mean age, 58.9 years) with tests that measured attention, memory and mood, using a double-blind, randomized, crossover design. Compared with the young group, the middle-aged group had significantly poorer verbal episodic memory, focused, divided, and sustained attention; they also differed in their subjective responses at the end of testing. Bioglycin significantly improved retrieval from episodic memory in both the young and the middle-aged groups, but it did not affect focused or divided attention. However, the middle-aged men significantly benefited from Bioglycin in the sustained-attention task. The effects of Bioglycin differed from those of other cognitive enhancers in that it was without stimulant properties or significant effects on mood, and it primarily improved memory rather than attention. It is likely to be of benefit in young or older people in situations where high retrieval of information is needed or when performance is impaired by jet lag, shift work, or disrupted sleep. It may also benefit the impaired retrieval shown in patients with schizophrenia, Parkinson's disease, and Huntington's disease.

Look what I found! Poison hunting on eBay.

PubMed

Cantrell, F Lee

2005-01-01

Many substances deemed too dangerous for commercial use are still available to the general public. The purchase of these substances may potentially place members of the general public at risk for serious poisonings. This study was designed to document the large variety of dangerous poisons readily available on a popular online auction Web site. Methods. Over a 10-month period, the online auction Web site eBays was searched daily using the terms "poison" and "contents." Product name, active ingredients, what form the product is in, amount in container, and relative toxicity rating (Clinical Toxicology of Commercial Products, Gosselin, et al.) were recorded. If available, pictures of the products were saved. One hundred twenty-one individual products were identified. Fifty-five were in solid/tablet form, 37 were powders, and 29 were liquids. Product containers were full for 56 items and partially full for 65. Twenty-four products contained ingredients rated as "supertoxic" and included strychnine (10), arsenic trioxide (8), cyanide (2) and nicotine, pilocarpine, phosphorus, powdered conium maculatum (1 each). Sixty-three products contained "extremely toxic" ingredients including thallium, picrotoxin, soluble barium, antimony, mercury, arsenates, podophyllin, fluoride, zinc phosphide, atropine, scopolamine, and plant extracts of gelsemium, aconite, larkspur, and croton. Twenty-one products contained "very toxic" ingredients including lead, copper, camphor, caffeine, theobromine, creosote, pyrogallic acid, sparteine, quinine, lindane, warfarin, phenol, and digitalis. The remaining 13 were "moderately-slightly toxic." While the viability of the labeled ingredients could not be verified, the transportation, handling, and potential utilization of these dangerous poisons by the general public could result in serious poisonings.

Activation of cannabinoid CB1 receptors modulates evoked action potentials in rat retinal ganglion cells.

PubMed

Jiang, Shu-Xia; Li, Qian; Wang, Xiao-Han; Li, Fang; Wang, Zhong-Feng

2013-08-25

Activation of cannabinoid CB1 receptors (CB1Rs) regulates a variety of physiological functions in the vertebrate retina through modulating various types of ion channels. The aim of the present study was to investigate the effects of this receptor on cell excitability of rat retinal ganglion cells (RGCs) in retinal slices using whole-cell patch-clamp techniques. The results showed that under current-clamped condition perfusing WIN55212-2 (WIN, 5 μmol/L), a CB1R agonist, did not significantly change the spontaneous firing frequency and resting membrane potential of RGCs. In the presence of cocktail synaptic blockers, including excitatory postsynaptic receptor blockers CNQX and D-APV, and inhibitory receptor blockers bicuculline and strychnine, perfusion of WIN (5 μmol/L) hardly changed the frequencies of evoked action potentials by a series of positive current injection (from +10 to +100 pA). Phase-plane plot analysis showed that both average threshold voltage for triggering action potential and delay time to reach threshold voltage were not affected by WIN. However, WIN significantly decreased +dV/dtmax and -dV/dtmax of action potentials, suggestive of reduced rising and descending velocities of action potentials. The effects of WIN were reversed by co-application of SR141716, a CB1R selective antagonist. Moreover, WIN did not influence resting membrane potential of RGCs with synaptic inputs being blocked. These results suggest that activation of CB1Rs may regulate intrinsic excitability of rat RGCs through modulating evoked action potentials.

The Sleep-Promoting and Hypothermic Effects of Glycine are Mediated by NMDA Receptors in the Suprachiasmatic Nucleus

PubMed Central

Kawai, Nobuhiro; Sakai, Noriaki; Okuro, Masashi; Karakawa, Sachie; Tsuneyoshi, Yosuke; Kawasaki, Noriko; Takeda, Tomoko; Bannai, Makoto; Nishino, Seiji

2015-01-01

The use of glycine as a therapeutic option for improving sleep quality is a novel and safe approach. However, despite clinical evidence of its efficacy, the details of its mechanism remain poorly understood. In this study, we investigated the site of action and sleep-promoting mechanisms of glycine in rats. In acute sleep disturbance, oral administration of glycine-induced non-rapid eye movement (REM) sleep and shortened NREM sleep latency with a simultaneous decrease in core temperature. Oral and intracerebroventricular injection of glycine elevated cutaneous blood flow (CBF) at the plantar surface in a dose-dependent manner, resulting in heat loss. Pretreatment with N-methyl-D-aspartate (NMDA) receptor antagonists AP5 and CGP78608 but not the glycine receptor antagonist strychnine inhibited the CBF increase caused by glycine injection into the brain. Induction of c-Fos expression was observed in the hypothalamic nuclei, including the medial preoptic area (MPO) and the suprachiasmatic nucleus (SCN) shell after glycine administration. Bilateral microinjection of glycine into the SCN elevated CBF in a dose-dependent manner, whereas no effect was observed when glycine was injected into the MPO and dorsal subparaventricular zone. In addition, microinjection of D-serine into the SCN also increased CBF, whereas these effects were blocked in the presence of L-701324. SCN ablation completely abolished the sleep-promoting and hypothermic effects of glycine. These data suggest that exogenous glycine promotes sleep via peripheral vasodilatation through the activation of NMDA receptors in the SCN shell. PMID:25533534

Variability of Stimulant Levels in Nine Sports Supplements Over a 9-Month Period.

PubMed

Attipoe, Selasi; Cohen, Pieter A; Eichner, Amy; Deuster, Patricia A

2016-10-01

Many studies have found that some dietary supplement product labels do not accurately reflect the actual ingredients. However, studies have not been performed to determine if ingredients in the same dietary supplement product vary over time. The objective of this study was to assess the consistency of stimulant ingredients in popular sports supplements sold in the United States over a 9-month period. Three samples of nine popular sports supplements were purchased over the 9-month period. The 27 samples were analyzed for caffeine and several other stimulants (including adulterants). The identity and quantity of stimulants were compared with stimulants listed on the label and stimulants found at earlier time points to determine the variability in individual products over the 9-month period. The primary outcome measure was the variability of stimulant amounts in the products examined. Many supplements did not contain the same number and quantity of stimulants at all time points over the 9-month period. Caffeine content varied widely in five of the six caffeinated supplements compared with the initial measurement (-7% to +266%). In addition, the stimulants-synephrine, octopamine, cathine, ephedrine, pseudoephedrine, strychnine, and methylephedrine-occurred in variable amounts in eight of the nine products. The significance of these findings is uncertain: the sample size was insufficient to support statistical analysis. In our sample of nine popular sports supplements, the presence and quantity of stimulants varied over a 9-month period. However, future studies are warranted to determine if the variability found is significant and generalizable to other supplements.

Influence of picolinic acid on seizure susceptibility in mice.

PubMed

Cioczek-Czuczwar, Anna; Czuczwar, Piotr; Turski, Waldemar Andrzej; Parada-Turska, Jolanta

2017-02-01

The mechanism of drug resistance in epilepsy remains unknown. Picolinic acid (PIC) is an endogenous metabolite of the kynurenine pathway and a chelating agent added to dietary supplements. Both inhibitory and excitatory properties of PIC were reported. The aim of this study was to determine the influence of exogenously applied PIC upon the electroconvulsive threshold and the activity of chemical convulsants in eight models of epilepsy in mice. All experiments were performed on adult male Swiss albino mice. Electroconvulsions were induced through ear clip electrodes. The electroconvulsive threshold (current strength necessary to induce tonic seizures in 50% of the tested group - CS 50 ) was estimated for control animals and animals pretreated with PIC. To determine the possible convulsant activity of PIC, it was administered subcutaneously or intracerebroventricularly in increasing doses to calculate the CD 50 values (doses of convulsants necessary to produce seizures in 50% of the animals). Chemical convulsions were induced by challenging the animals with increasing doses of convulsant to calculate the CD 50 values. The following convulsants were used: 4-aminopyridine, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, bicuculline, N-methyl-d-aspartate, nicotine, pentylenetrazole, pilocarpine hydrochloride and strychnine nitrate. PIC significantly decreased the electroconvulsive threshold and, after intracerebroventricular injection, but not subcutaneous, produced convulsions. Of the studied convulsants, only the activity of pilocarpine hydrochloride was significantly enhanced by PIC. PIC enhances seizure activity and potentially may play a role in the pathogenesis of drug resistant epilepsy. Future studies should focus on the interactions between PIC and antiepileptic drugs. Copyright © 2016. Published by Elsevier Urban & Partner Sp. z o.o.

Physiological characterization, localization and synaptic inputs of bursting and nonbursting neurons in the trigeminal principal sensory nucleus of the rat.

PubMed

Athanassiadis, T; Westberg, K-G; Olsson, K A; Kolta, A

2005-12-01

A population of neurons in the trigeminal principal sensory nucleus (NVsnpr) fire rhythmically during fictive mastication induced in the in vivo rabbit. To elucidate whether these neurons form part of the central pattern generator (CPG) for mastication, we performed intracellular recordings in brainstem slices taken from young rats. Two cell types were defined, nonbursting (63%) and bursting (37%). In response to membrane depolarization, bursting cells, which dominated in the dorsal part of the NVsnpr, fired an initial burst followed by single spikes or recurring bursts. Non-bursting neurons, scattered throughout the nucleus, fired single action potentials. Microstimulation applied to the trigeminal motor nucleus (NVmt), the reticular border zone surrounding the NVmt, the parvocellular reticular formation or the nucleus reticularis pontis caudalis (NPontc) elicited a postsynaptic potential in 81% of the neurons tested for synaptic inputs. Responses obtained were predominately excitatory and sensitive to glutamatergic antagonists DNQX and/or APV. Some inhibitory and biphasic responses were also evoked. Bicuculline methiodide or strychnine blocked the IPSPs indicating that they were mediated by GABA(A) or glycinergic receptors. About one-third of the stimulations activated both types of neurons antidromically, mostly from the masseteric motoneuron pool of NVmt and dorsal part of NPontc. In conclusion, our new findings show that some neurons in the dorsal NVsnpr display both firing properties and axonal connections which support the hypothesis that they may participate in masticatory pattern generation. Thus, the present data provide an extended basis for further studies on the organization of the masticatory CPG network.

Corticospinal control of antagonistic muscles in the cat.

PubMed

Ethier, Christian; Brizzi, Laurent; Giguère, Dominic; Capaday, Charles

2007-09-01

We recently suggested that movement-related inter-joint muscle synergies are recruited by selected excitation and selected release from inhibition of cortical points. Here we asked whether a similar cortical mechanism operates in the functional linking of antagonistic muscles. To this end experiments were done on ketamine-anesthetized cats. Intracortical microstimulation (ICMS) and intramuscular electromyographic recordings were used to find and characterize wrist, elbow and shoulder antagonistic motor cortical points. Simultaneous ICMS applied at two cortical points, each evoking activity in one of a pair of antagonistic muscles, produced co-contraction of antagonistic muscle pairs. However, we found an obvious asymmetry in the strength of reciprocal inhibition; it was always significantly stronger on physiological extensors than flexors. Following intravenous injection of a single bolus of strychnine, a cortical point at which only a physiological flexor was previously activated also elicited simultaneous activation of its antagonist. This demonstrates that antagonistic corticospinal neurons are closely grouped, or intermingled. To test whether releasing a cortical point from inhibition allows it to be functionally linked with an antagonistic cortical point, one of three GABA(A) receptor antagonists, bicuculline, gabazine or picrotoxin, was injected iontophoretically at one cortical point while stimulation was applied to an antagonistic cortical point. This coupling always resulted in co-contraction of the represented antagonistic muscles. Thus, antagonistic motor cortical points are linked by excitatory intracortical connections held in check by local GABAergic inhibition, with reciprocal inhibition occurring at the spinal level. Importantly, the asymmetry of cortically mediated reciprocal inhibition would appear significantly to bias muscle maps obtained by ICMS in favor of physiological flexors.

Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons.

PubMed

Nakahata, Yoshihisa; Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Kuriu, Toshihiko; Hirata, Hiromi; Moorhouse, Andrew J; Ishibashi, Hitoshi; Nabekura, Junichi

2017-01-01

Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo . While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca 2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system.

An assessment of the potential of protopine to inhibit microsomal drug metabolising enzymes and prevent chemical-induced hepatotoxicity in rodents.

PubMed

Janbaz, K H; Saeed, S A; Gilani, A H

1998-09-01

The potential of protopine to inhibit microsomal drug metabolising enzymes (MDM E) and prevent paracetamol- and CCl4-induced hepatotoxicity was studied in rats. Paracetamol at the dose of 640 mg kg-1 produced hepatic damage in rats as manifested by the rise in serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) to 972+/-186 and 624+/-131 IU (mean+/-sem; n=10), respectively, compared to respective control values of 101+/-29 and 64+/-18 IU. Pretreatment of rats with protopine (11 mg kg-1, orally twice daily for 2 days) lowered significantly the respective serum AST and ALT levels (P<0.05) to 289+/-52 and 178+/-43 IU. The hepatotoxic dose of CCl4 (1.5 ml kg-1; orally) raised serum AST and ALT levels to 543+/-89 and 387+/-69 IU (mean+/-sem; n=10), respectively, compared to respective control values of 98+/-28 and 56+/-17 IU. The same dose of protopine (11 mg kg-1) was able to prevent significantly (P<0.05), the CCl4-induced rise in serum enzymes and the estimated values of AST and ALT were 168+/-36 and 93+/-28 IU, respectively. Protopine caused prolongation (P<0.05) in pentobarbital (55 mg kg-1)-induced sleep as well as potentiated strychnine-induced toxicity in rats, suggestive of an inhibitory effect on MDME. These results indicate that protopine exhibits anti-hepatotoxic action which may be mediated through inhibition of MDME. Copyright 1998 The Italian Pharmacological Society

On the pharmacology of ascending, descending and recurrent postsynatic inhibition of the cuneothalamic relay cells in the cat

PubMed Central

Kelly, J. S.; Renaud, L. P.

1973-01-01

1. In cats decerebrated or anaesthetized with pentobarbitone, cells of the middle third of the cuneate nucleus that were excited by tactile stimulation of the ipsilateral forelimb (responding to displacement of hairs, skin or joints) and inhibited by electrical stimulation of the contralateral pyramid, were invariably inhibited by electrical stimulation of the ipsilateral forepaw and the contralateral forelimb nerves. 2. In 50% of the cats, the cells were more fully identified by placing electrodes stereotaxically in the contralateral medial lemniscus. Recurrent inhibition was always a concomitant of the antidromic action potential. 3. The intensity and the duration of inhibition evoked by all of these pathways was totally resistant to iontophoretic and intravenous strychnine in doses at least 5 times that required to block completely the response of the same cells to iontophoretic glycine and was extremely sensitive to either iontophoretic bicuculline or picrotoxin. 4. Although the inhibition was invariably sensitive to intravenous picrotoxin, no significant change occurred in the duration or intensity of the inhibition when bicuculline was administered intravenously (5 or 6 times) as repeated doses of 0·2 mg/kg. 5. Postsynaptic inhibition in the cuneate may be mediated by γ-aminobutyric acid released from the nerve terminals of a common pool of interneurones shared by ascending, descending and recurrent pathways. Since the receptors involved in this pathway are resistant to intravenous bicuculline, they may well be distinct from those responsible for changes in the primary afferent terminal excitability, usually believed to be associated with presynaptic inhibition. PMID:4357959

Fast non-genomic effects of progesterone-derived neurosteroids on nociceptive thresholds and pain symptoms.

PubMed

Charlet, Alexandre; Lasbennes, François; Darbon, Pascal; Poisbeau, Pierrick

2008-10-31

Fast Inhibitory controls mediated by glycine (GlyRs) and GABAA receptors (GABAARs) play an important role to prevent the apparition of pathological pain symptoms of allodynia and hyperalgesia. The use of positive allosteric modulators of these receptors, specifically expressed in the spinal cord, may represent an interesting strategy to limit or block pain expression. In this study, we have used stereoisomers of progesterone metabolites, acting only via non-genomic effects, in order to evaluate the contribution of GlyRs and GABAARs for the reduction of mechanical and thermal heat hypernociception. We show that 3alpha neurosteroids were particularly efficient to elevate nociceptive thresholds in naive animal. It also reduced mechanical allodynia and thermal heat hyperalgesia in the carrageenan model of inflammatory pain. This effect is likely to be mediated by GABAA receptors since 3beta isomer was inefficient. More interestingly, 3alpha5beta neurosteroid was only efficient on mechanical allodynia while having no effect on thermal heat hyperalgesia. We characterized these paradoxical effects of 3alpha5beta neurosteroid using the strychnine and bicuculline models of allodynia. We clearly show that 3alpha5beta neurosteroid exerts an antinociceptive effect via a positive allosteric modulation of GABAARs but, at the same time, is pronociceptive by reducing GlyR function. This illustrates the importance of the inhibitory amino acid receptor channels and their allosteric modulators in spinal pain processing. Moreover, our results indicate that neurosteroids, which are synthesized in the dorsal horn of the spinal cord and have limited side effects, may be of significant interest in order to treat pathological pain symptoms.

Mutations M287L and Q266I in the Glycine Receptor α1 Subunit Change Sensitivity to Volatile Anesthetics in Oocytes and Neurons, but Not the Minimal Alveolar Concentration in Knockin Mice

PubMed Central

Borghese, Cecilia M.; Xiong, Wei; Oh, S. Irene; Ho, Angel; Mihic, S. John; Zhang, Li; Lovinger, David M.; Homanics, Gregg E.; Eger, Edmond I; Harris, R. Adron

2012-01-01

Background Volatile anesthetics (VAs) alter the function of key central nervous system proteins but it is not clear which, if any, of these targets mediates the immobility produced by VAs in the face of noxious stimulation. A leading candidate is the glycine receptor, a ligand-gated ion channel important for spinal physiology. VAs variously enhance such function, and blockade of spinal GlyRs with strychnine affects the minimal alveolar concentration (an anesthetic EC50) in proportion to the degree of enhancement. Methods We produced single amino acid mutations into the glycine receptorα1 subunit that increased (M287L, third transmembrane region) or decreased (Q266I, second transmembrane region) sensitivity to isoflurane in recombinant receptors, and introduced such receptors into mice. The resulting knockin mice presented impaired glycinergic transmission, but heterozygous animals survived to adulthood, and we determined the effect of isoflurane on glycine-evoked responses of brain stem neurons from the knockin mice, and the minimal alveolar concentration for isoflurane and other VAs in the immature and mature knockin mice. Results Studies of glycine-evoked currents in brain stem neurons from knock-in mice confirmed the changes seen with recombinant receptors. No increases in the minimal alveolar concentration were found in knockin mice, but the minimal alveolar concentration for isoflurane and enflurane (but not halothane) decreased in 2-week-old Q266I mice. This change is opposite to the one expected for a mutation that decreases the sensitivity to volatile anesthetics. Conclusion Taken together, these results indicate that glycine receptors containing the α1 subunit are not likely to be crucial for the action of isoflurane and other VAs. PMID:22885675

Glycinergic inhibition of BAT sympathetic premotor neurons in rostral raphe pallidus.

PubMed

Conceição, Ellen Paula Santos da; Madden, Christopher J; Morrison, Shaun F

2017-06-01

The rostral raphe pallidus (rRPa) contains sympathetic premotor neurons controlling thermogenesis in brown adipose tissue (BAT). We sought to determine whether a tonic activation of glycine A receptors (Gly A R) in the rRPa contributes to the inhibitory regulation of BAT sympathetic nerve activity (SNA) and of cardiovascular parameters in anesthetized rats. Nanoinjection of the Gly A R antagonist, strychnine (STR), into the rRPa of intact rats increased BAT SNA (peak: +495%), BAT temperature (T BAT , +1.1°C), expired CO 2 , (+0.4%), core body temperature (T CORE , +0.2°C), mean arterial pressure (MAP, +4 mmHg), and heart rate (HR, +57 beats/min). STR into rRPa in rats with a postdorsomedial hypothalamus transection produced similar increases in BAT thermogenic and cardiovascular parameters. Glycine nanoinjection into the rRPa evoked a potent inhibition of the cooling-evoked increases in BAT SNA (nadir: -74%), T BAT (-0.2°C), T CORE (-0.2°C), expired CO 2 (-0.2%), MAP (-8 mmHg), and HR (-22 beats/min) but had no effect on the increases in these variables evoked by STR nanoinjection into rRPa. Nanoinjection of GABA into the rRPa inhibited the STR-evoked BAT SNA (nadir: -86%) and reduced the expired CO 2 (-0.4%). Blockade of glutamate receptors in rRPa reduced the STR-evoked increases in BAT SNA (nadir: -61%), T BAT (-0.5°C), expired CO 2 (-0.3%), MAP (-9 mmHg), and HR (-33 beats/min). We conclude that a tonically active glycinergic input to the rRPa contributes to the inhibitory regulation of the discharge of BAT sympathetic premotor neurons and of BAT thermogenesis and energy expenditure. Copyright © 2017 the American Physiological Society.

Synthesis, molecular modelling, and preliminary anticonvulsant activity evaluation of novel naphthalen-2-yl acetate and 1,6-dithia-4,9-diazaspiro [4.4] nonane-3,8-dione derivatives.

PubMed

Ghareb, Nagat; Abdel Daim, Mohamed M; El-Sayed, Norhan M; Elgawish, Mohamed Saleh

2017-04-01

The synthesis, pharmacological evaluation and molecular modelling study of novel naphthalen-2-yl acetate and 1,6-dithia-4,9-diazaspiro [4.4]nonane-3,8-dione derivatives as potential anticonvulsant agents are described. The newly synthesized compounds were characterized by both analytical and spectral data. Alkylation of 1H-imidazole or substituted piperazine with 1-(2-naphthyl)-2-bromoethanone (2) gave naphthalen-2-yl 2-(1H-imidazol-1-yl) acetate (3) and naphthalen-2-yl 2-(substituted piperazin-1-yl) acetate (4-8). Moreover, condensation of naphthalen-2-yl 2-bromoacetate or 2-bromo-1-(naphthalen-2-yl) ethanone with hydrazine hydrate and acetylacetone resulted in the formation of the cyclic pyrazole products 9 and 13. Sonication of naphthalen-2-yl acetate (1) with 2-chloropyridine, 2-chloropyrimidine and 2-(chloromethyl) oxirane gave naphthalen-2-yl 2-(pyridin-2-yl) acetate (10), naphthalen-2-yl 2-(pyrimidin-2-yl) acetate (11) and naphthalen-2-yl-3-(oxiran-2-yl) propanoate (12) respectively. Cyclocondensation reaction of 2-iminothiazolidin-4-one (14) with thioglycolic acid, thiolactic acid and thiomalic acid gave 1,6-dithia-4,9-diazaspiro [4.4]nonane-3,8-dione derivatives (15-17). The compounds were testedin vivofor the anticonvulsant activity by delaying strychnine-induced seizures. The diazaspirononane (17) and 1-(2-naphthyl)-2-bromoethanone (2) showed a high significant delay in the onset of convulsion and prolongation of survival time compared to phenobarbital. The molecular modelling study of anticonvulsant activity of synthesized compounds showed a CNS depressant activity via modulation of benzodiazepine allosteric site in GABA-A receptors. Copyright © 2017 Elsevier Inc. All rights reserved.

Functional modulation of strychnine-sensitive glycine receptors in rat hippocampal pyramidal neurons by amyloid-β protein (1-42).

PubMed

Bukanova, J V; Sharonova, I N; Skrebitsky, V G

2016-11-15

Amyloid-β peptide (Aβ) is considered a key protein in the pathogenesis of Alzheimer's disease because of its neurotoxicity, resulting in impaired synaptic function and memory. On the other hand, it was demonstrated that low (picomolar) concentrations of Aβ enhance synaptic plasticity and memory, suggesting that in the healthy brain, physiological Aβ concentrations are necessary for normal cognitive functions. In the present study, we found that Aβ (1-42) in concentrations of 10 pМ - 100nМ enhanced desensitization of the glycine-activated current in isolated CA3 pyramidal neurons and also reversibly suppressed its peak amplitude during short (600ms) co-application with agonist. The effect was most prominent at low glycine concentrations. When glycine receptors were activated by other receptor agonists - taurine and β-alanine, the changes of current kinetics and amplitudes induced by Aβ had a similar character. When Aβ (100 pM) was added to the bath solution, it caused, besides acceleration of desensitization, more pronounced reduction of peak current amplitude. This effect developed slowly, during a few minutes, and was more prominent at saturating concentrations of agonists. The results suggest that Aβ interacts with glycine receptors through three different mechanisms - by enhancing receptor desensitization, by rapid inhibition of the receptor, and also by means of a slowly developing inhibition of the amplitude of the current, possibly through intracellular mechanisms. The observed changes in the activity of glycine receptors induced by Aβ can lead to suppression of the tonic inhibition of hippocampal neurons mediated by extrasynaptic glycine receptors. Copyright © 2016 Elsevier B.V. All rights reserved.

Glycine Receptor Activation Impairs ATP-Induced Calcium Transients in Cultured Cortical Astrocytes

PubMed Central

Morais, Tatiana P.; Coelho, David; Vaz, Sandra H.; Sebastião, Ana M.; Valente, Cláudia A.

2018-01-01

In central nervous system, glycine receptor (GlyR) is mostly expressed in the spinal cord and brainstem, but glycinergic transmission related elements have also been identified in the brain. Astrocytes are active elements at the tripartite synapse, being responsible for the maintenance of brain homeostasis and for the fine-tuning of synaptic activity. These cells communicate, spontaneously or in response to a stimulus, by elevations in their cytosolic calcium (calcium transients, Ca2+T) that can be propagated to other cells. How these Ca2+T are negatively modulated is yet poorly understood. In this work, we evaluated GlyR expression and its role on calcium signaling modulation in rat brain astrocytes. We first proved that GlyR, predominantly subunits α2 and β, was expressed in brain astrocytes and its localization was confirmed in the cytoplasm and astrocytic processes by immunohistochemistry assays. Calcium imaging experiments in cultured astrocytes showed that glycine (500 μM), a GlyR agonist, caused a concentration-dependent reduction in ATP-induced Ca2+T, an effect abolished by the GlyR antagonist, strychnine (0.8 μM), as well as by nocodazole (1 μM), known to impair GlyR anchorage to the plasma membrane. This effect was mimicked by activation of GABAAR, another Cl--permeable channel. In summary, we demonstrated that GlyR activation in astrocytes mediates an inhibitory effect upon ATP induced Ca2+T, which most probably involves changes in membrane permeability to Cl- and requires GlyR anchorage at the plasma membrane. GlyR in astrocytes may thus be part of a mechanism to modulate astrocyte-to-neuron communication. PMID:29386993

A potentially novel nicotinic receptor in Aplysia neuroendocrine cells.

PubMed

White, Sean H; Carter, Christopher J; Magoski, Neil S

2014-07-15

Nicotinic receptors form a diverse group of ligand-gated ionotropic receptors with roles in both synaptic transmission and the control of excitability. In the bag cell neurons of Aplysia, acetylcholine activates an ionotropic receptor, which passes inward current to produce a long-lasting afterdischarge and hormone release, leading to reproduction. While testing the agonist profile of the cholinergic response, we observed a second current that appeared to be gated only by nicotine and not acetylcholine. The peak nicotine-evoked current was markedly smaller in magnitude than the acetylcholine-induced current, cooperative (Hill value of 2.7), had an EC50 near 500 μM, readily recovered from desensitization, showed Ca(2+) permeability, and was blocked by mecamylamine, dihydro-β-erythroidine, or strychnine, but not by α-conotoxin ImI, methyllycaconitine, or hexamethonium. Aplysia transcriptome analysis followed by PCR yielded 20 full-length potential nicotinic receptor subunits. Sixteen of these were predicted to be cation selective, and real-time PCR suggested that 15 of the 16 subunits were expressed to varying degrees in the bag cell neurons. The acetylcholine-induced current, but not the nicotine current, was reduced by double-strand RNA treatment targeted to both subunits ApAChR-C and -E. Conversely, the nicotine-evoked current, but not the acetylcholine current, was lessened by targeting both subunits ApAChR-H and -P. To the best of our knowledge, this is the first report suggesting that a nicotinic receptor is not gated by acetylcholine. Separate receptors may serve as a means to differentially trigger plasticity or safeguard propagation by assuring that only acetylcholine, the endogenous agonist, initiates large enough responses to trigger reproduction. Copyright © 2014 the American Physiological Society.

Hypocretin-2 (orexin-B) modulation of superficial dorsal horn activity in rat

PubMed Central

Grudt, Timothy J; van den Pol, Anthony N; Perl, Edward R

2002-01-01

The hypothalamic peptides hypocretin-1 (orexin A) and hypocretin-2 (Hcrt-2; orexin B) are important in modulating behaviours demanding arousal, including sleep and appetite. Fibres containing hypocretin project from the hypothalamus to the superficial dorsal horn (SDH) of the spinal cord (laminae I and II); however, the effects produced by hypocretins on SDH neurones are unknown. To study the action of Hcrt-2 on individual SDH neurones, tight-seal, whole-cell recordings were made with biocytin-filled electrodes from rat lumbar spinal cord slices. In 19 of 63 neurones, Hcrt-2 (30 nm to 1 μm) evoked an inward (excitatory) current accompanied by an increase in baseline noise. The inward current and noise were unaffected by TTX but were blocked by the P2X purinergic receptor antagonist suramin (300–500 μm). Hcrt-2 (30 nm to 1 μm) increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) in the majority of neurones. The sIPSC increase was blocked by strychnine (1 μm) and by TTX (1 μm), suggesting that the increased sIPSC frequency was glycine and action potential dependent. Hcrt-2 increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in a few neurones but had no effect on dorsal root-evoked EPSCs in these or in other neurones. Neurones located in outer lamina II, particularly radial and vertical cells, were most likely to respond to Hcrt-2. We conclude that Hcrt-2 has excitatory effects on certain SDH neurones, some of which exert inhibitory influences on other cells of the region, consistent with the perspective that hypocretin has a role in orchestrating reactions related to arousal, including nociception, pain and temperature sense. PMID:11790816

Processing noxious information at the subnucleus reticularis dorsalis (SRD) of anesthetized cats: wind-up mechanisms.

PubMed

Soto, Cristina; Martín-Cora, Francisco J; Leiras, Roberto; Velo, Patricia; Canedo, Antonio

2008-11-15

With the exception of one monkey's study, where wind-up was not reported, electrophysiological data from SRD neurons were obtained in rodents where they show wind-up. This work was designed to examine the response properties of SRD neurons in anesthetized cats to study how general the data from rats may be. Since cat's SRD cells showed wind-up, its underlying mechanisms were approached, an issue not previously addressed at supraspinal level. Electrical stimulation, extracellular (combined with microiontophoresis) and intracellular techniques revealed that A delta information reaches the SRD via the ventrolateral cord, whereas C information preferentially follows a dorsal route. Wind-up was usually generated by spinal and peripheral stimulation, but it was also evoked either by stimulating the nucleus reticularis gigantocellularis (NRGc), even after spinal cord section and bilateral full thickness removal of the cerebral cortex, or by applying microiontophoretic pulses of l-glutamate at 0.3-1 Hz. Wind-up relied on afferent repetitive activity gradually depolarizing the SRD neurons leading 3-4.5 Hz subthreshold membrane rhythmic activity to threshold. Riluzole retarded wind-up generation and decreased the number of spikes per stimulus during wind-up. GABA or glycine abolished spontaneous and sensory-evoked activity and bicuculline, but not strychnine, increased spontaneous and stimulus-evoked activity. These results demonstrate that wind-up at the SRD is not merely the reflection of spinal wind-up, but (i) can be locally generated, (ii) is partially dependent upon persistent sodium currents, and (iii) is under the modulation of a tonic GABAa-dependent inhibition decreasing SRD excitability. Injury and/or inflammation producing tonic C-fiber activation will surpass tonic inhibition generating wind-up.

Mutation of a Zinc-Binding Residue in the Glycine Receptor α1 Subunit Changes Ethanol Sensitivity In Vitro and Alcohol Consumption In Vivo

PubMed Central

McCracken, Lindsay M.; Blednov, Yuri A.; Trudell, James R.; Benavidez, Jillian M.; Betz, Heinrich

2013-01-01

Ethanol is a widely used drug, yet an understanding of its sites and mechanisms of action remains incomplete. Among the protein targets of ethanol are glycine receptors (GlyRs), which are potentiated by millimolar concentrations of ethanol. In addition, zinc ions also modulate GlyR function, and recent evidence suggests that physiologic concentrations of zinc enhance ethanol potentiation of GlyRs. Here, we first built a homology model of a zinc-bound GlyR using the D80 position as a coordination site for a zinc ion. Next, we investigated in vitro the effects of zinc on ethanol action at recombinant wild-type (WT) and mutant α1 GlyRs containing the D80A substitution, which eliminates zinc potentiation. At D80A GlyRs, the effects of 50 and 200 mM ethanol were reduced as compared with WT receptors. Also, in contrast to what was seen with WT GlyRs, neither adding nor chelating zinc changed the magnitude of ethanol enhancement of mutant D80A receptors. Next, we evaluated the in vivo effects of the D80A substitution by using heterozygous Glra1(D80A) knock-in (KI) mice. The KI mice showed decreased ethanol consumption and preference, and they displayed increased startle responses compared with their WT littermates. Other behavioral tests, including ethanol-induced motor incoordination and strychnine-induced convulsions, revealed no differences between the KI and WT mice. Together, our findings indicate that zinc is critical in determining the effects of ethanol at GlyRs and suggest that zinc binding at the D80 position may be important for mediating some of the behavioral effects of ethanol action at GlyRs. PMID:23230213

Ethanol Reduces Neuronal Excitability of Lateral Orbitofrontal Cortex Neurons Via a Glycine Receptor Dependent Mechanism

PubMed Central

Badanich, Kimberly A; Mulholland, Patrick J; Beckley, Jacob T; Trantham-Davidson, Heather; Woodward, John J

2013-01-01

Trauma-induced damage to the orbitofrontal cortex (OFC) often results in behavioral inflexibility and impaired judgment. Human alcoholics exhibit similar cognitive deficits suggesting that OFC neurons are susceptible to alcohol-induced dysfunction. A previous study from this laboratory examined OFC mediated cognitive behaviors in mice and showed that behavioral flexibility during a reversal learning discrimination task was reduced in alcohol-dependent mice. Despite these intriguing findings, the actions of alcohol on OFC neuron function are unknown. To address this issue, slices containing the lateral OFC (lOFC) were prepared from adult C57BL/6J mice and whole-cell patch clamp electrophysiology was used to characterize the effects of ethanol (EtOH) on neuronal function. EtOH (66 mM) had no effect on AMPA-mediated EPSCs but decreased those mediated by NMDA receptors. EtOH (11–66 mM) also decreased current-evoked spike firing and this was accompanied by a decrease in input resistance and a modest hyperpolarization. EtOH inhibition of spike firing was prevented by the GABAA antagonist picrotoxin, but EtOH had no effect on evoked or spontaneous GABA IPSCs. EtOH increased the holding current of voltage-clamped neurons and this action was blocked by picrotoxin but not the more selective GABAA antagonist biccuculine. The glycine receptor antagonist strychnine also prevented EtOH's effect on holding current and spike firing, and western blotting revealed the presence of glycine receptors in lOFC. Overall, these results suggest that acutely, EtOH may reduce lOFC function via a glycine receptor dependent process and this may trigger neuroadaptive mechanisms that contribute to the impairment of OFC-dependent behaviors in alcohol-dependent subjects. PMID:23314219

Anticonvulsant effects of ethanol stem bark extract of Lannea barteri (Anacardiaceae) in mice and chicks.

PubMed

Garba, K; Yaro, A H; Ya'u, J

2015-08-22

Preparation of Lannea barteri is used in the treatment of epilepsy, gastritis, childhood convulsions among other uses in northern Nigeria for many years. The popularity of its efficacy is well established among the Traditional Medical Practitioners. The present study aimed at screening the ethanol stem bark extract of Lannea barteri for possible anticonvulsant action. Anticonvulsant screening was carried out using pentylenetetrazole (PTZ), strychnine (STN) and picrotoxin (PTC) induced seizures in mice while Maximal electroshock (MES) test was carried out in day old chicks. Preliminary phytochemical screening of the extract was performed on the extract. The intraperitoneal median lethal dose (LD50) was carried out in mice. The intraperitoneal (i.p.) LD50 of the extract was estimated to be 567.70 mg/kg in mice. Lannea barteri (160 mg/kg) significantly (p ≤ 0.05) delayed the mean onset of seizures induced by PTZ when compared with normal saline treated group. Similarly, the extract at 160 mg/kg significantly (p ≤ 0.05) prolonged the latency of convulsion induced by STN. Lannea barteri (40 mg/kg) significantly (p ≤ 0.05) delayed the mean onset of seizures induced by picrotoxin in mice. The extracts at all the doses tested showed no observable effect in decreasing the mean recovery time of convulsed chicks in MEST. Flavonoids, alkaloids, tannins, saponins and glycosides were found present in the stem bark extract. Our findings revealed that the ethanol stem bark extract of Lannea barteri contained bioactive constituents that may be useful in the management of petit mal epilepsy and supports the ethnomedical claim for the use of its stem bark in the management of epilepsy. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Glycine- and GABA-mimetic Actions of Shilajit on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice

PubMed Central

Yin, Hua; Yang, Eun Ju; Park, Soo Joung

2011-01-01

Shilajit, a medicine herb commonly used in Ayurveda, has been reported to contain at least 85 minerals in ionic form that act on a variety of chemical, biological, and physical stressors. The substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis (Vc) are involved in orofacial nociceptive processing. Shilajit has been reported to be an injury and muscular pain reliever but there have been few functional studies of the effect of Shilajit on the SG neurons of the Vc. Therefore, whole cell and gramicidin-perfotrated patch clamp studies were performed to examine the action mechanism of Shilajit on the SG neurons of Vc from mouse brainstem slices. In the whole cell patch clamp mode, Shilajit induced short-lived and repeatable inward currents under the condition of a high chloride pipette solution on all the SG neurons tested. The Shilajit-induced inward currents were concentration dependent and maintained in the presence of tetrodotoxin (TTX), a voltage gated Na+ channel blocker, CNQX, a non-NMDA glutamate receptor antagonist, and AP5, an NMDA receptor antagonist. The Shilajit-induced responses were partially suppressed by picrotoxin, a GABAA receptor antagonist, and totally blocked in the presence of strychnine, a glycine receptor antagonist, however not affected by mecamylamine hydrochloride (MCH), a nicotinic acetylcholine receptor antagonist. Under the potassium gluconate pipette solution at holding potential 0 mV, Shilajit induced repeatable outward current. These results show that Shilajit has inhibitory effects on the SG neurons of Vc through chloride ion channels by activation of the glycine receptor and GABAA receptor, indicating that Shilajit contains sedating ingredients for the central nervous system. These results also suggest that Shilajit may be a potential target for modulating orofacial pain processing. PMID:22128261

Glycine- and GABA-mimetic Actions of Shilajit on the Substantia Gelatinosa Neurons of the Trigeminal Subnucleus Caudalis in Mice.

PubMed

Yin, Hua; Yang, Eun Ju; Park, Soo Joung; Han, Seong Kyu

2011-10-01

Shilajit, a medicine herb commonly used in Ayurveda, has been reported to contain at least 85 minerals in ionic form that act on a variety of chemical, biological, and physical stressors. The substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis (Vc) are involved in orofacial nociceptive processing. Shilajit has been reported to be an injury and muscular pain reliever but there have been few functional studies of the effect of Shilajit on the SG neurons of the Vc. Therefore, whole cell and gramicidin-perfotrated patch clamp studies were performed to examine the action mechanism of Shilajit on the SG neurons of Vc from mouse brainstem slices. In the whole cell patch clamp mode, Shilajit induced short-lived and repeatable inward currents under the condition of a high chloride pipette solution on all the SG neurons tested. The Shilajit-induced inward currents were concentration dependent and maintained in the presence of tetrodotoxin (TTX), a voltage gated Na(+) channel blocker, CNQX, a non-NMDA glutamate receptor antagonist, and AP5, an NMDA receptor antagonist. The Shilajit-induced responses were partially suppressed by picrotoxin, a GABA(A) receptor antagonist, and totally blocked in the presence of strychnine, a glycine receptor antagonist, however not affected by mecamylamine hydrochloride (MCH), a nicotinic acetylcholine receptor antagonist. Under the potassium gluconate pipette solution at holding potential 0 mV, Shilajit induced repeatable outward current. These results show that Shilajit has inhibitory effects on the SG neurons of Vc through chloride ion channels by activation of the glycine receptor and GABA(A) receptor, indicating that Shilajit contains sedating ingredients for the central nervous system. These results also suggest that Shilajit may be a potential target for modulating orofacial pain processing.

Distinct presynaptic regulation of dopamine release through NMDA receptors in striosome- and matrix-enriched areas of the rat striatum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krebs, M.O.; Trovero, F.; Desban, M.

1991-05-01

Striosome- and matrix-enriched striatal zones were defined in coronal and sagittal brain sections of the rat, on the basis of {sup 3}H-naloxone binding to mu-opiate receptors (a striosome-specific marker). Then, using a new in vitro microsuperfusion device, the NMDA (50 microM)-evoked release of newly synthesized {sup 3}H-dopamine ({sup 3}H-DA) was examined in these four striatal areas under Mg(2+)-free conditions. The amplitudes of the responses were different in striosomal (171 +/- 6% and 161 +/- 5% of the spontaneous release) than in matrix areas (223 +/- 6% and 248 +/- 12%), even when glycine (1 or 100 microM) was coapplied (inmore » the presence of 1 microM strychnine). In the four areas, the NMDA-evoked release of {sup 3}H-DA was blocked completely by Mg{sup 2}{sup +} (1 mM) or (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801; 1 microM) and almost totally abolished by kynurenate (100 microM). Because the tetrodotoxin (TTX)-resistant NMDA-evoked release of {sup 3}H-DA was similar in striosome- (148 +/- 5% and 152 +/- 6%) or matrix-enriched (161 +/- 5% and 156 +/- 7%) areas, the indirect (TTX-sensitive) component of NMDA-evoked responses, which involves striatal neurons and/or afferent fibers, seems more important in the matrix- than in the striosome-enriched areas. The modulation of DA release by cortical glutamate and/or aspartate-containing inputs through NMDA receptors in the matrix appears thus to be partly distinct from that observed in the striosomes, providing some functional basis for the histochemical striatal heterogeneity.« less

Are pacemaker properties required for respiratory rhythm generation in adult turtle brain stems in vitro?

PubMed

Johnson, Stephen M; Wiegel, Liana M; Majewski, David J

2007-08-01

The role of pacemaker properties in vertebrate respiratory rhythm generation is not well understood. To address this question from a comparative perspective, brain stems from adult turtles were isolated in vitro, and respiratory motor bursts were recorded on hypoglossal (XII) nerve rootlets. The goal was to test whether burst frequency could be altered by conditions known to alter respiratory pacemaker neuron activity in mammals (e.g., increased bath KCl or blockade of specific inward currents). While bathed in artificial cerebrospinal fluid (aCSF), respiratory burst frequency was not correlated with changes in bath KCl (0.5-10.0 mM). Riluzole (50 microM; persistent Na(+) channel blocker) increased burst frequency by 31 +/- 5% (P < 0.05) and decreased burst amplitude by 42 +/- 4% (P < 0.05). In contrast, flufenamic acid (FFA, 20-500 microM; Ca(2+)-activated cation channel blocker) reduced and abolished burst frequency in a dose- and time-dependent manner (P < 0.05). During synaptic inhibition blockade with bicuculline (50 microM; GABA(A) channel blocker) and strychnine (50 muM; glycine receptor blocker), rhythmic motor activity persisted, and burst frequency was directly correlated with extracellular KCl (0.5-10.0 mM; P = 0.005). During synaptic inhibition blockade, riluzole (50 microM) did not alter burst frequency, whereas FFA (100 microM) abolished burst frequency (P < 0.05). These data are most consistent with the hypothesis that turtle respiratory rhythm generation requires Ca(2+)-activated cation channels but not pacemaker neurons, which thereby favors the group-pacemaker model. During synaptic inhibition blockade, however, the rhythm generator appears to be transformed into a pacemaker-driven network that requires Ca(2+)-activated cation channels.

Analgesic and anticonvulsant effects of extracts from the leaves of Kalanchoe crenata (Andrews) Haworth (Crassulaceae).

PubMed

Nguelefack, T B; Nana, P; Atsamo, A D; Dimo, T; Watcho, P; Dongmo, A B; Tapondjou, L A; Njamen, D; Wansi, S L; Kamanyi, A

2006-06-15

Kalanchoe crenata Andr. (Crassulaceae) is a fleshy herbaceous plant used in the African traditional medicine as remedies against otitis, headache, inflammations, convulsions and general debility. In the present work, the analgesic effects of methylene chloride/methanol (1:1) (CH(2)Cl(2)/CH(3)OH) extract and its hexane, methylene chloride (CH(2)Cl(2)), ethyl acetate, n-butanol fractions and aqueous residue have been evaluated using acetic acid, formalin and pressure test. The anticonvulsant effects of the CH(2)Cl(2)/CH(3)OH extract were also investigated on seizures induced by pentylenetetrazol (PTZ 70 mg/kg), strychnine sulphate (STN 2.5 mg/kg) and thiosemicarbazide (TSC 50 mg/kg). CH(2)Cl(2)/CH(3)OH extract and its fractions, administered orally at the doses of 150 and 300 mg/kg, exhibited protective effect of at least 30% on the pain induced by acetic acid. The CH(2)Cl(2) fraction at 300 mg/kg showed a maximal effect of 78.49%. The CH(2)Cl(2)/CH(3)OH extract and its CH(2)Cl(2) fraction at the doses of 150 and 300 mg/kg significantly reduced the first phase of pain induced by formalin while the second phase was completely inhibited. The CH(2)Cl(2) fraction produced more than 45% reduction in the sensitivity to pain induced by pressure. The CH(2)Cl(2)/CH(3)OH extract of Kalanchoe crenata significantly increased the latency period in seizures induced by PTZ and significantly reduced the duration of seizures induced by the three convulsant agents. The extract protected 20% of animals against death in seizures induced by TSC and STN. These results suggest a peripheral and central analgesic activities as well as an anticonvulsant effect of the leaves of Kalanchoe crenata.

Screening approach by ultra-high performance liquid chromatography-tandem mass spectrometry for the blood quantification of thirty-four toxic principles of plant origin. Application to forensic toxicology.

PubMed

Carlier, Jérémy; Guitton, Jérôme; Romeuf, Ludovic; Bévalot, Fabien; Boyer, Baptiste; Fanton, Laurent; Gaillard, Yvan

2015-01-15

Plant poisonings have left their mark on history and still cause many deaths, whether intentional or accidental. The means to show toxicological evidence of such poisonings should be implemented with great care. This article presents a technique for measuring thirty-nine toxic principles of plant origin in the blood, covering a large amount of toxins from local or exotic plants: α-lobeline, α-solanine, aconitine, ajmaline, atropine, brucine, cephalomannine, colchicine, convallatoxin, cymarine, cytisine, digitoxin, digoxin, emetine, gelsemine, ibogaine, jervine, kavain, lanatoside C, lupanine, mitragynine, neriifolin, oleandrin, ouabain, paclitaxel, physostigmine, pilocarpine, podophyllotoxin, proscillaridin A, reserpine, retrorsine, ricinine, scopolamine, senecionine, sparteine, strophanthidin, strychnine, veratridine and yohimbine. Analysis was carried out using an original ultra-high performance liquid chromatography separation coupled with tandem mass spectrometry detection. Extraction was a standard solid phase extraction performed on Oasis(®) HLB cartridge. Thirty-four of the thirty-nine compounds were put through a validation procedure. The assay was linear in the calibration curve range from 0.5 or 5 μg/L to 1000 μg/L according to the compounds. The method is sensitive (LOD from 0.1 to 1.6 μg/L). The within-day precision of the assay was less than 22.5% at the LLOQ, and the between-day precision was less than 21.5% for 10 μg/L for all the compounds included. The assay accuracy was in the range of 87.4 to 119.8% for the LLOQ. The extraction recovery and matrix effect ranged from 30 to 106% and from -30 to 14%, respectively. It has proven useful and effective in several difficult forensic cases. Copyright © 2014 Elsevier B.V. All rights reserved.

THE RESUSCITATION OF THE CENTRAL NERVOUS SYSTEM OF MAMMALS

PubMed Central

Stewart, G. N.; Guthrie, C. C.; Burns, R. L.; Pike, F. H.

1906-01-01

The cerebral circulation was interrupted for periods of three to eighty-one minutes by ligation of the innominate and left subclavian arteries proximal to the origin of the vertebral, in ninety-three cats. Eleven dogs were used in the earlier experiments. The eye reflexes disappear very quickly and a period of high blood pressure follows the occlusion immediately; vagus inhibition causes cardiac slowing and a fall in blood pressure, followed by a second rise after the vagus center succumbs to anaemia. Respiration stops temporarily (twenty to sixty seconds) after the beginning of occlusion, and then follows a series of strong gasps of the Cheyne-Stokes type, after which it stops until some time after the restoration of the cerebral circulation. The respiratory and vagus centers lose their power of functioning at approximately the same time. Asphyxial slowing of the heart may occur without the agency of the vagus center. The blood pressure slowly falls to a level which is maintained throughout the remainder of the period of occlusion. The anterior part of the cord and the encephalon lose all function; no reflexes are obtainable. The reflexes of the posterior part of the cord persist; the intravenous injection of strychnine does not affect the anterior part of the cord during the period of occlusion; but does affect the posterior portion of the cord. There is no secretion of tears or saliva, and the intra-ocular pressure is reduced. The blood pressure falls still more after release of the cerebra arteries, but soon begins to rise. The respiration returns suddenly, two to sixty minutes after restoration of the cerebral circulation, the first gasp being a strong one. The rate gradually increases until rapid enough for natural respiration. The eye reflexes and intra-ocular tension return more gradually, ten minutes to three hours after restoration of the cerebral circulation. The anterior part of the cord recovers its functions gradually. The first reflexes occur only on the same side as the stimulus, crossing of reflexes, to involve the other side, not occurring till later. As a rule, all reflexes return, and a short period of quiet follows. The anterior part of the cord again becomes irritable to strychnine, but succumbs to its action before the normal part. Spasms, of tonic, clonic, or mixed type, then appear, terminating in (a) death, (b) partial or (c) complete recovery. In partial recovery, disturbances of locomotion, such as walking in a circle, paralysis, dementia, loss of sight, hearing, and general intelligence, characterize the post-convulsive period. After complete recovery, there is a return to normal deportment. No gross lesions of the nervous system, other than a congested appearance of the previously anæmic area, were observed. Transection of the spinal cord stops the spasms below the level of section. Hemisection of the cord stops the spasms on the same side, below the level of section. Death, without any return of the reflexes after release of the cerebral arteries, has followed an occlusion of seven and one-half minutes. Respiration has returned after an occlusion of one hour. Five animals have recovered completely after an occlusion of seven minutes or more. Only one animal has recovered completely after an occlusion of fifteen minutes. No animal has recovered completely after an occlusion of twenty minutes. In Herzen's 26 resuscitation of an animal after several hours of cerebral anæmia, there must have been some anastomotic channels to the brain. Mayer's 27 limit of ten to fifteen minutes of cerebral anæmia, beyond which resuscitation is not practicable, is close to the correct one. It appears to us that, in cases of resuscitation two hours after cessation of the heart-beat, (Prus., loc.cit.) the auricles must have kept up a slow but, in some degree, an efficient movement of the blood through the brain. The truth of this suggestion might be tested by introducing some easily recognized, non-diffusible substance into a vein after the heart-beat ceases to affect a manometer, and later searching for it in the brain and other parts of the body. But, whatever the reason, cerebral anaemia in these cases must have been less complete than in our experiments. The histological alterations of the cord and brain are now being studied. The results will be published later. PMID:19867041

Hypothalamic digoxin, hemispheric chemical dominance, and oncogenesis: evidence from multiple myeloma.

PubMed

Kurup, Ravi Kumar; Kurup, Paramesware Achutha

2003-12-01

This study assessed the changes in the isoprenoid pathway and its metabolites digoxin, dolichol, and ubiquinone in multiple myeloma. The isoprenoid pathway and digoxin status were also studied for comparison in individuals of differing hemispheric dominance to find out the rote of cerebral dominance in the genesis of multiple myeloma and neoplasms. The following parameters were assessed: isoprenoid pathway metabolites, tyrosine and tryptophan catabolites, glycoconjugate metabolism, RBC membrane composition, and free radical metabolism--in multiple myeloma, as well as in individuals of differing hemispheric dominance. There was elevation in plasma HMG CoA reductase activity, serum digoxin, and dolichol, and a reduction in RBC membrane Na(+)-K+ ATPase activity, serum ubiquinone, and magnesium levels. Serum tryptophan, serotonin, nicotine, strychnine, and quinolinic acid were elevated, while tyrosine, dopamine, noradrenaline, and morphine were decreased. The total serum glycosaminoglycans and glycosaminoglycan fractions, the activity of GAG degrading enzymes and glycohydrolases, carbohydrate residues of glycoproteins, and serum glycolipids were elevated. The RBC membrane glycosaminoglycans, hexose, and fucose residues of glycoproteins, cholesterol, and phospholipids were reduced. The activity of all free-radical scavenging enzymes, concentration of glutathione, iron binding capacity, and ceruloplasmin decreased significantly, while the concentration of lipid peroxidation products and nitric oxide increased. Hyperdigoxinemia-related altered intracellular Ca++/Mg++ ratios mediated oncogene activation, dolichol-induced altered glycoconjugate metabolism, and ubiquinone deficiency-related mitochondrial dysfunction can contribute to the pathogenesis of multiple myeloma. The biochemical patterns obtained in multiple myeloma are similar to those obtained in left-handed/right hemispheric chemically dominant individuals by the dichotic listening test. But all the patients with multiple myeloma were right-handed/left hemispheric dominant by the dichotic listening test. Hemispheric chemical dominance has no correlation with handedness or the dichotic listening test. Multiple myeloma occurs in right hemispheric chemically dominant individuals and is a reflection of altered brain function.

Perturbations of Respiratory Rhythm and Pattern by Disrupting Synaptic Inhibition within Pre-Bötzinger and Bötzinger Complexes123

PubMed Central

Koizumi, Hidehiko; Mosher, Bryan; Tariq, Mohammad F.; Zhang, Ruli; Molkov, Yaroslav I.

2016-01-01

The pre-Bötzinger (pre-BötC) and Bötzinger (BötC) complexes are the brainstem compartments containing interneurons considered to be critically involved in generating respiratory rhythm and motor pattern in mammals. Current models postulate that both generation of the rhythm and coordination of the inspiratory-expiratory pattern involve inhibitory synaptic interactions within and between these regions. Both regions contain glycinergic and GABAergic neurons, and rhythmically active neurons in these regions receive appropriately coordinated phasic inhibition necessary for generation of the normal three-phase respiratory pattern. However, recent experiments attempting to disrupt glycinergic and GABAergic postsynaptic inhibition in the pre-BötC and BötC in adult rats in vivo have questioned the critical role of synaptic inhibition in these regions, as well as the importance of the BötC, which contradicts previous physiological and pharmacological studies. To further evaluate the roles of synaptic inhibition and the BötC, we bilaterally microinjected the GABAA receptor antagonist gabazine and glycinergic receptor antagonist strychnine into the pre-BötC or BötC in anesthetized adult rats in vivo and in perfused in situ brainstem–spinal cord preparations from juvenile rats. Muscimol was microinjected to suppress neuronal activity in the pre-BötC or BötC. In both preparations, disrupting inhibition within pre-BötC or BötC caused major site-specific perturbations of the rhythm and disrupted the three-phase motor pattern, in some experiments terminating rhythmic motor output. Suppressing BötC activity also potently disturbed the rhythm and motor pattern. We conclude that inhibitory circuit interactions within and between the pre-BötC and BötC critically regulate rhythmogenesis and are required for normal respiratory motor pattern generation. PMID:27200412

Hydrogen sulfide mediates hypoxia-induced relaxation of trout urinary bladder smooth muscle.

PubMed

Dombkowski, Ryan A; Doellman, Meredith M; Head, Sally K; Olson, Kenneth R

2006-08-01

Hydrogen sulfide (H2S) is a recently identified gasotransmitter that may mediate hypoxic responses in vascular smooth muscle. H2S also appears to be a signaling molecule in mammalian non-vascular smooth muscle, but its existence and function in non-mammalian non-vascular smooth muscle have not been examined. In the present study we examined H2S production and its physiological effects in urinary bladder from steelhead and rainbow trout (Oncorhynchus mykiss) and evaluated the relationship between H2S and hypoxia. H2S was produced by trout bladders, and its production was sensitive to inhibitors of cystathionine beta-synthase and cystathionine gamma-lyase. H2S produced a dose-dependent relaxation in unstimulated and carbachol pre-contracted bladders and inhibited spontaneous contractions. Bladders pre-contracted with 80 mmol l(-1) KCl were less sensitive to H2S than bladders contracted with either 80 mmol l(-1) KC2H3O2 (KAc) or carbachol, suggesting that some of the H2S effects are mediated through an ion channel. However, H2S relaxation of bladders was not affected by the potassium channel inhibitors, apamin, charybdotoxin, 4-aminopyridine, and glybenclamide, or by chloride channel/exchange inhibitors 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt, tamoxifen and glybenclamide, or by the presence or absence of extracellular HCO3-. Inhibitors of neuronal mechanisms, tetrodotoxin, strychnine and N-vanillylnonanamide were likewise ineffective. Hypoxia (aeration with N2) also relaxed bladders, was competitive with H2S for relaxation, and it was equally sensitive to KCl, and unaffected by neuronal blockade or the presence of extracellular HCO3-. Inhibitors of H2S synthesis also inhibited hypoxic relaxation. These experiments suggest that H2S is a phylogenetically ancient gasotransmitter in non-mammalian non-vascular smooth muscle and that it serves as an oxygen sensor/transducer, mediating the effects of hypoxia.

The Plant Alkaloid Camptothecin as a Novel Antifouling Compound for Marine Paints: Laboratory Bioassays and Field Trials.

PubMed

Feng, Dan Qing; He, Jian; Chen, Si Yu; Su, Pei; Ke, Cai Huan; Wang, Wei

2018-06-02

The extensive use of copper and booster biocides in antifouling (AF) paints has raised environmental concerns and the need to develop new AF agents. In the present study, 18 alkaloids derived from terrestrial plants were initially evaluated for AF activity using laboratory bioassays with the bryozoan Bugula neritina and the barnacle Balanus albicostatus. The results showed that 4 of the 18 alkaloids were effective in inhibiting larval settlement of B. neritina, with an EC 50 range of 6.18 to 43.11 μM, and 15 of the 18 alkaloids inhibited larval settlement of B. albicostatus, with EC 50 values ranging from 1.18 to 67.58 μM. Field trials that incorporated five alkaloids respectively into paints with 20% w/w indicated an in situ AF efficiency of evodiamine, strychnine, camptothecin (CPT), and cepharanthine, with the most potent compound being CPT, which also exhibited stronger AF efficiency than the commercial antifoulants cuprous oxide and zinc pyrithione in the field over a period of 12 months. Further field trials with different CPT concentrations (0.1 to 20% w/w) in the paints suggested a concentration-dependent AF performance in the natural environment, and the effective concentrations to significantly inhibit settlement of biofoulers in the field were ≥ 0.5% w/w (the efficiency of 0.5% w/w lasted for 2 months). Moreover, CPT toxicity against the crustacean Artemia salina, the planktonic microalgae Phaeodactylum tricornutum and Isochrysis galbana, was examined. The results showed that 24 h LC 50 of CPT against A. salina was 20.75 μM, and 96 h EC 50 (growth inhibition) values of CPT to P. tricornutum and I. galbana were 55.81 and 6.29 μM, respectively, indicating that CPT was comparatively less toxic than several commercial antifoulants previously reported. Our results suggest the novel potential application of CPT as an antifoulant.

Nitric oxide facilitates GABAergic neurotransmission in the cat oculomotor system: a physiological mechanism in eye movement control

PubMed Central

Moreno-López, Bernardo; Escudero, Miguel; Estrada, Carmen

2002-01-01

Nitric oxide (NO) synthesis by prepositus hypoglossi (PH) neurons is necessary for the normal performance of horizontal eye movements. We have previously shown that unilateral injections of NO synthase (NOS) inhibitors into the PH nucleus of alert cats produce velocity imbalance without alteration of the eye position control, both during spontaneous eye movements and the vestibulo-ocular reflex (VOR). This NO effect is exerted on the dorsal PH neuropil, whose fibres increase their cGMP content when stimulated by NO. In an attempt to determine whether NO acts by modulation of a specific neurotransmission system, we have now compared the oculomotor effects of NOS inhibition with those produced by local blockade of glutamatergic, GABAergic or glycinergic receptors in the PH nucleus of alert cats. Both glutamatergic antagonists used, 2-amino-5-phosphonovaleric acid (APV) and 2,3-dihydro-6-nitro-7-sulphamoyl-benzo quinoxaline (NBQX), induced a nystagmus contralateral to that observed upon NOS inhibition, and caused exponential eye position drift. In contrast, bicuculline and strychnine induced eye velocity alterations similar to those produced by NOS inhibitors, suggesting that NO oculomotor effects were due to facilitation of some inhibitory input to the PH nucleus. To investigate the anatomical location of the putative NO target neurons, the retrograde tracer Fast Blue was injected in one PH nucleus, and the brainstem sections containing Fast Blue-positive neurons were stained with double immunohistochemistry for NO-sensitive cGMP and glutamic acid decarboxylase. GABAergic neurons projecting to the PH nucleus and containing NO-sensitive cGMP were found almost exclusively in the ipsilateral medial vestibular nucleus and marginal zone. The results suggest that the nitrergic PH neurons control their own firing rate by a NO-mediated facilitation of GABAergic afferents from the ipsilateral medial vestibular nucleus. This self-control mechanism could play an important role in the maintenance of the vestibular balance necessary to generate a stable and adequate eye position signal. PMID:11927688

Behavioral and anticonvulsant effects of the standardized extract of Ficus platyphylla stem bark.

PubMed

Chindo, Ben A; Ya'U, Jamilu; Danjuma, Nuhu M; Okhale, Samuel E; Gamaniel, Karniyus S; Becker, Axel

2014-06-11

Decoctions of Ficus platyphylla Del.-Holl (Family: Moraceae) are used in Nigeria׳s folk medicine for the management of epilepsy and their efficacies are widely acclaimed among the rural communities of northern Nigeria. The aim of the study is to examine the behavioral and anticonvulsant properties of the standardized methanol extract of Ficus platyphylla (FP) stem bark, in order to scientifically describe its potential values in the management of convulsive disorders. High performance liquid chromatography (HPLC) and preliminary phytochemical analysis of the methanol extract were utilized and the intraperitoneal median lethal dose (LD50) determined in mice. The effects of FP were investigated on some murine models of behavior and its anticonvulsant effects studied on pentylenetetrazole (PTZ)-, strychnine (STN)-, picrotoxin (PCT)-, isoniazid (INH)-, aminophylline (AMI)- and maximal electroshock (MES)-induced seizures in mice. The intraperitoneal oral LD50 of FP was estimated to be 5000mg/kg. FP significantly reduced the locomotor activities including the total distance covered, speed, active time and rearing counts. It shortened the onset and prolonged the duration of diazepam-induced sleep, but had no effect on motor coordination on the rota-rod treadmill or beam-walking assay in mice at the doses tested. The extract protected the mice against PTZ- and STN-induced seizures and significantly delayed the latencies of myoclonic jerks and tonic seizures induced by all the standard convulsant agents (PTZ, PCT, INH, STN and AMI) used in this study, but failed to protect the mice against MES seizures at the doses tested. The HPLC fingerprint of the extract shows a spectrum profile characteristic of Ficus platyphylla, while the preliminary phytochemical screening revealed the presence of saponins, flavonoids and tannins. Our study provides scientific evidence that FP may contain psychoactive principles with potential anticonvulsant properties, thus supporting further development of the psychoactive components of this plant as anticonvulsant agents. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Contralateral Effects and Binaural Interactions in Dorsal Cochlear Nucleus

PubMed Central

2005-01-01

The dorsal cochlear nucleus (DCN) receives afferent input from the auditory nerve and is thus usually thought of as a monaural nucleus, but it also receives inputs from the contralateral cochlear nucleus as well as descending projections from binaural nuclei. Evidence suggests that some of these commissural and efferent projections are excitatory, whereas others are inhibitory. The goals of this study were to investigate the nature and effects of these inputs in the DCN by measuring DCN principal cell (type IV unit) responses to a variety of contralateral monaural and binaural stimuli. As expected, the results of contralateral stimulation demonstrate a mixture of excitatory and inhibitory influences, although inhibitory effects predominate. Most type IV units are weakly, if at all, inhibited by tones but are strongly inhibited by broadband noise (BBN). The inhibition evoked by BBN is also low threshold and short latency. This inhibition is abolished and excitation is revealed when strychnine, a glycine-receptor antagonist, is applied to the DCN; application of bicuculline, a GABAA-receptor antagonist, has similar effects but does not block the onset of inhibition. Manipulations of discrete fiber bundles suggest that the inhibitory, but not excitatory, inputs to DCN principal cells enter the DCN via its output pathway, and that the short latency inhibition is carried by commissural axons. Consistent with their respective monaural effects, responses to binaural tones as a function of interaural level difference are essentially the same as responses to ipsilateral tones, whereas binaural BBN responses decrease with increasing contralateral level. In comparison to monaural responses, binaural responses to virtual space stimuli show enhanced sensitivity to the elevation of a sound source in ipsilateral space but reduced sensitivity in contralateral space. These results show that the contralateral inputs to the DCN are functionally relevant in natural listening conditions, and that one role of these inputs is to enhance DCN processing of spectral sound localization cues produced by the pinna. PMID:16075189

Artifacts in time-resolved NUS: A case study of NOE build-up curves from 2D NOESY.

PubMed

Dass, Rupashree; Kasprzak, Paweł; Koźmiński, Wiktor; Kazimierczuk, Krzysztof

2016-04-01

Multidimensional NMR spectroscopy requires time-consuming sampling of indirect dimensions and so is usually used to study stable samples. However, dynamically changing compounds or their mixtures commonly occur in problems of natural science. Monitoring them requires the use multidimensional NMR in a time-resolved manner - in other words, a series of quick spectra must be acquired at different points in time. Among the many solutions that have been proposed to achieve this goal, time-resolved non-uniform sampling (TR-NUS) is one of the simplest. In a TR-NUS experiment, the signal is sampled using a shuffled random schedule and then divided into overlapping subsets. These subsets are then processed using one of the NUS reconstruction methods, for example compressed sensing (CS). The resulting stack of spectra forms a temporal "pseudo-dimension" that shows the changes caused by the process occurring in the sample. CS enables the use of small subsets of data, which minimizes the averaging of the effects studied. Yet, even within these limited timeframes, the sample undergoes certain changes. In this paper we discuss the effect of varying signal amplitude in a TR-NUS experiment. Our theoretical calculations show that the variations within the subsets lead to t1-noise, which is dependent on the rate of change of the signal amplitude. We verify these predictions experimentally. As a model case we choose a novel 2D TR-NOESY experiment in which mixing time is varied in parallel with shuffled NUS in the indirect dimension. The experiment, performed on a sample of strychnine, provides a near-continuous NOE build-up curve, whose shape closely reflects the t1-noise level. 2D TR-NOESY reduces the measurement time compared to the conventional approach and makes it possible to verify the theoretical predictions about signal variations during TR-NUS. Copyright © 2016 Elsevier Inc. All rights reserved.

Characterization of Two Mutations, M287L and Q266I, in the α1 Glycine Receptor Subunit That Modify Sensitivity to Alcohols

PubMed Central

Borghese, Cecilia M.; Blednov, Yuri A.; Quan, Yu; Iyer, Sangeetha V.; Xiong, Wei; Mihic, S. John; Zhang, Li; Lovinger, David M.; Trudell, James R.; Homanics, Gregg E.

2012-01-01

Glycine receptors (GlyRs) are inhibitory ligand-gated ion channels. Ethanol potentiates glycine activation of the GlyR, and putative binding sites for alcohol are located in the transmembrane (TM) domains between and within subunits. To alter alcohol sensitivity of GlyR, we introduced two mutations in the GlyR α1 subunit, M287L (TM3) and Q266I (TM2). After expression in Xenopus laevis oocytes, both mutants showed a reduction in glycine sensitivity and glycine-induced maximal currents. Activation by taurine, another endogenous agonist, was almost abolished in the M287L GlyR. The ethanol potentiation of glycine currents was reduced in the M287L GlyR and eliminated in Q266I. Physiological levels of zinc (100 nM) potentiate glycine responses in wild-type GlyR and also enhance the ethanol potentiation of glycine responses. Although zinc potentiation of glycine responses was unchanged in both mutants, zinc enhancement of ethanol potentiation of glycine responses was absent in M287L GlyRs. The Q266I mutation decreased conductance but increased mean open time (effects not seen in M287L). Two lines of knockin mice bearing these mutations were developed. Survival of homozygous knockin mice was impaired, probably as a consequence of impaired glycinergic transmission. Glycine showed a decreased capacity for displacing strychnine binding in heterozygous knockin mice. Electrophysiology in isolated neurons of brain stem showed decreased glycine-mediated currents and decreased ethanol potentiation in homozygous knockin mice. Molecular models of the wild-type and mutant GlyRs show a smaller water-filled cavity within the TM domains of the Q266I α1 subunit. The behavioral characterization of these knockin mice is presented in a companion article (J Pharmacol Exp Ther 340:317–329, 2012). PMID:22037201

Cooperative interaction among the various regulatory sites within the NMDA receptor-channel complex in modulating the evoked responses to noxious thermal stimuli of spinal dorsal horn neurons in the cat.

PubMed

Song, X J; Zhao, Z Q

1998-05-01

Interactions among antagonists acting at different regulatory sites within the N-methyl-D-aspartate (NMDA) receptor-channel complex on the evoked responses to noxious thermal stimuli of wide dynamic range (WDR) neurons in spinal dorsal horn were studied on 21 adult anesthetized and spinalized cats. The responses of nociceptive spinal dorsal horn neurons to noxious heating (45-55 degrees C) of the glabrous skin of the unilateral hind paw were reduced markedly by iontophoretically applied antagonists. The specific recognition site antagonist, DL-2-amino-5-phosphonovaleratic acid (APV), the strychnine-insensitive glycine site antagonist 7-chlorokynurenic acid (7CKA), the polyamine site antagonist ifenprodil (IFEN), and the phencyclidine (PCP) site antagonists ketamine (KET) and MK-801 (40-100 nA) significantly reduced (t-tests, P < 0.01) the noxious thermal stimulus-evoked responses in about 70% of the neurons by (mean +/- SE) 54.1 +/- 5.8% (n = 19), 80.8 +/- 4.7% (n = 16), 51.1 +/- 6.4% (n = 10), 77 +/- 4.9% (n = 16) and 81.2 +/- 8.1% (n = 5), respectively. APV and IFEN were less effective in blocking noxious thermal stimuli-evoked responses than 7CKA, KET and MK-801 (ANOVA, P < 0.05). The responses were completely inhibited in some neurons. After co-administration of the antagonists, APV + 7CKA, APV + IFEN, 7CKA + IFEN, APV + KET and APV + MK-801, all at the subthreshold ejection current, the responses were reduced markedly in 13 of 16, 7 of 10, 5 of 10, 3 of 6 and 3 of 5 neurons, respectively. The present study suggests that blockage of any component of the NMDA receptor-channel complex antagonizes the NMDA receptor-mediated response, and that there are the cooperative interactions among the various regulatory sites within the NMDA receptor-channel complex in the transmission or modulation of spinal nociceptive thermal information.

Nanomolar Oxytocin Synergizes with Weak Electrical Afferent Stimulation to Activate the Locomotor CPG of the Rat Spinal Cord In Vitro

PubMed Central

Dose, Francesco; Zanon, Patrizia; Coslovich, Tamara; Taccola, Giuliano

2014-01-01

Synergizing the effect of afferent fibre stimulation with pharmacological interventions is a desirable goal to trigger spinal locomotor activity, especially after injury. Thus, to better understand the mechanisms to optimize this process, we studied the role of the neuropeptide oxytocin (previously shown to stimulate locomotor networks) on network and motoneuron properties using the isolated neonatal rat spinal cord. On motoneurons oxytocin (1 nM–1 μM) generated sporadic bursts with superimposed firing and dose-dependent depolarization. No desensitization was observed despite repeated applications. Tetrodotoxin completely blocked the effects of oxytocin, demonstrating the network origin of the responses. Recording motoneuron pool activity from lumbar ventral roots showed oxytocin mediated depolarization with synchronous bursts, and depression of reflex responses in a stimulus and peptide-concentration dependent fashion. Disinhibited bursting caused by strychnine and bicuculline was accelerated by oxytocin whose action was blocked by the oxytocin antagonist atosiban. Fictive locomotion appeared when subthreshold concentrations of NMDA plus 5HT were coapplied with oxytocin, an effect prevented after 24 h incubation with the inhibitor of 5HT synthesis, PCPA. When fictive locomotion was fully manifested, oxytocin did not change periodicity, although cycle amplitude became smaller. A novel protocol of electrical stimulation based on noisy waveforms and applied to one dorsal root evoked stereotypic fictive locomotion. Whenever the stimulus intensity was subthreshold, low doses of oxytocin triggered fictive locomotion although oxytocin per se did not affect primary afferent depolarization evoked by dorsal root pulses. Among the several functional targets for the action of oxytocin at lumbar spinal cord level, the present results highlight how small concentrations of this peptide could bring spinal networks to threshold for fictive locomotion in combination with other protocols, and delineate the use of oxytocin to strengthen the efficiency of electrical stimulation to activate locomotor circuits. PMID:24658101

ACh-induced hyperpolarization and decreased resistance in mammalian type II vestibular hair cells.

PubMed

Poppi, Lauren A; Tabatabaee, Hessam; Drury, Hannah R; Jobling, Phillip; Callister, Robert J; Migliaccio, Americo A; Jordan, Paivi M; Holt, Joseph C; Rabbitt, Richard D; Lim, Rebecca; Brichta, Alan M

2018-01-01

In the mammalian vestibular periphery, electrical activation of the efferent vestibular system (EVS) has two effects on afferent activity: 1) it increases background afferent discharge and 2) decreases afferent sensitivity to rotational stimuli. Although the cellular mechanisms underlying these two contrasting afferent responses remain obscure, we postulated that the reduction in afferent sensitivity was attributed, in part, to the activation of α9- containing nicotinic acetylcholine (ACh) receptors (α9*nAChRs) and small-conductance potassium channels (SK) in vestibular type II hair cells, as demonstrated in the peripheral vestibular system of other vertebrates. To test this hypothesis, we examined the effects of the predominant EVS neurotransmitter ACh on vestibular type II hair cells from wild-type (wt) and α9-subunit nAChR knockout (α9 -/- ) mice. Immunostaining for choline acetyltransferase revealed there were no obvious gross morphological differences in the peripheral EVS innervation among any of these strains. ACh application onto wt type II hair cells, at resting potentials, produced a fast inward current followed by a slower outward current, resulting in membrane hyperpolarization and decreased membrane resistance. Hyperpolarization and decreased resistance were due to gating of SK channels. Consistent with activation of α9*nAChRs and SK channels, these ACh-sensitive currents were antagonized by the α9*nAChR blocker strychnine and SK blockers apamin and tamapin. Type II hair cells from α9 -/- mice, however, failed to respond to ACh at all. These results confirm the critical importance of α9nAChRs in efferent modulation of mammalian type II vestibular hair cells. Application of exogenous ACh reduces electrical impedance, thereby decreasing type II hair cell sensitivity. NEW & NOTEWORTHY Expression of α9 nicotinic subunit was crucial for fast cholinergic modulation of mammalian vestibular type II hair cells. These findings show a multifaceted efferent mechanism for altering hair cell membrane potential and decreasing membrane resistance that should reduce sensitivity to hair bundle displacements.

The inhibitory effect of convulsant agents on the enzyme in brain which inactivates nerveside.

PubMed

Toh, C C

1969-07-01

1. An enzyme which can be extracted from brain inactivates nerveside in the optimum pH range 5.8-7.0.2. The polybasic acids trypan blue and its analogue trypan red, bromphenol blue and its analogue bromthymol blue at concentrations of 0.22 mM and ethylenediaminetetra-acetic acid (EDTA) at a concentration of 1 mM are strong inhibitors of the enzyme.3. Penicillin which is a monobasic carboxylic acid also inhibits the enzyme but only if concentrations as high as 3.6 mM are used. The antibiotic streptomycin which is a basic substance does not inhibit the enzyme.4. Caffeine at a concentration of 7.2 mM only weakly inhibits the enzyme.5. Chymotrypsin and wheat germ acid phosphatase also inactivate nerveside at pH 5.9 and are inhibited by the acidic dyes and penicillin. EDTA inhibits wheat germ phosphatase but activates chymotrypsin.6. Inactivation of nerveside by the brain enzyme and by wheat germ phosphatase is different from the action of chymotrypsin. Nerveside solutions incubated with chymotrypsin completely lose all biological activity whereas if incubation is carried out with either the brain enzyme or wheat germ acid phosphatase a residual biological activity remains even when the concentration of these two enzymes is increased. This residual biological activity is due to a peptide as it is destroyed by chymotrypsin.7. The manner in which nerveside is inactivated by the brain enzyme is uncertain as the preparation of the latter contained phosphodiesterase and protease activities which were similarly inhibited by the acid dyes, penicillin and EDTA.8. Pentylenetetrazole, picrotoxin, strychnine and tetanus toxin do not inhibit the brain enzyme.9. The nerveside-inactivating enzyme is not identical with the Substance P-inactivating enzyme in brain as the former is inhibited by EDTA while the latter is not.

Participation of the IKK-α/β complex in the inhibition of the TNF-α/NF-κB pathway by glycine: Possible involvement of a membrane receptor specific to adipocytes.

PubMed

Contreras-Nuñez, Erika; Blancas-Flores, Gerardo; Cruz, Miguel; Almanza-Perez, Julio Cesar; Gomez-Zamudio, Jaime H; Ventura-Gallegosc, Jose Luis; Zentella-Dehesa, Alejandro; Roberto-Lazzarini; Roman-Ramos, Ruben; Alarcon-Aguilar, Francisco Javier

2018-06-01

Glycine modulates inflammatory processes mediated by macrophages and adipocytes through decreasing the secretion of TNF-α, IL-6, and leptin, while increasing adiponectin. These effects have been associated with the inactivation of NF-κB in response to TNF-α, across an increase of its inhibitor IκB-α in adipocytes. However, glycine upstream mainly influences the IκB kinase (IKK) complex, a multi-protein kinase complex considered a critical point in regulation of the NF-κB pathway; whether that is responsible for the TNF-α-induced phosphorylation of IkB has not been explored. Additionally, although previous studies have described glycine interactions with specific receptors (GlyR) in different immune system cell types, it is currently unknown whether adipocytes present GlyR. In this research, participation of the IKK-α/β complex in the inhibition of the TNF-α/NF-κB pathway by glycine was evaluated and associated with the synthesis and secretion of inflammatory cytokines in 3T3-L1 adipocytes. Furthermore, we also explored GlyR expression, its localization on the plasmatic membrane, intracellular calcium concentrations [Ca 2+ ] i and strychnine antagonist action over the GlyR in these cells. Glycine decreased the IKK-α/β complex and the phosphorylation of NF-κB, diminishing the expression and secretion of IL-6 and TNF-α, but increasing that of adiponectin. GlyR expression and its fluorescence in the plasma membrane were increased in the presence of glycine. In addition, glycine decreased [Ca 2+ ] i ; whereas strychnine + glycine treatment inhibited the activation of NF-κB observed with glycine. In conclusion, the reduction of TNF-α and IL-6 and suppression of the TNF-α/NF-κB pathway by glycine may be explained in part by inhibition of the IKK-α/β complex, with a possible participation of GlyR in 3T3-L1 adipocytes. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

A hypothalamic digoxin-mediated model for autism.

PubMed

Kurup, Ravi Kumar; Kurup, Parameswara Achutha

2003-11-01

The isoprenoid pathway and its metabolites--digoxin, dolichol, and ubiquinone--were assessed in autism. The isoprenoid pathway and digoxin status was also studied for comparison in individuals of differing hemispheric dominance to determine the role of cerebral dominance in the genesis of autism. There was an upregulation of the isoprenoid pathway as evidenced by elevated HMG CoA reductase activity in autism. Digoxin, an endogenous Na+-K+ ATPase inhibitor secreted by the hypothalamus, was found to be elevated and RBC membrane Na+-K+ ATPase activity was found to be reduced in autism. Membrane Na+-K+ ATPase inhibition can result in increased intracellular Ca2+ and reduced magnesium levels. Hypothalamic digoxin can modulate conscious and subliminal perception and its dysfunction may lead to autism. Digoxin can also preferentially upregulate tryptophan transport over tyrosine resulting in increased levels of depolarizing tryptophan catabolites--serotonin, quinolinic acid (NMDA agonist), strychnine (blocks glycinergic inhibitory transmission), and nicotine (promotes dopamine release) and decreased levels of hyperpolarizing tyrosine catabolites--dopamine, noradrenaline, and morphine--contributing to membrane Na+-K+ ATPase inhibition. Increased nicotine levels can produce increased dopaminergic transmission in the presence of low dopamine levels. NMDA excitotoxicity could result from hypomagnesemia induced by membrane Na+-K+ ATPase inhibition and quinolinic acid, an NMDA agonist acting on the NMDA receptor. Hypomagnesemia and increased dolichol level can affect glycoconjugate metabolism and membranogenesis leading on to disordered synaptic connectivity in the limbic allocortex and defective presentation of viral antigens and neuronal antigens contributing to autoimmunity and viral persistence important in the pathogenesis. Membrane Na+-K+ ATPase inhibition can produce immune activation, a component of autoimmunity. Mitochondrial dysfunction consequent to altered calcium/magnesium ratios and reduced ubiquinone levels can result in increased free radical generation and reduced free radical scavenging and defective apoptosis leading to abnormal synaptogenesis. Autism can thus be considered a syndrome of hypothalamic digoxin hypersecretion consequent to an upregulated isoprenoid pathway. The biochemical patterns including hyperdigoxinemia observed in autism correlated with those obtained in right hemispheric chemical dominance. Right hemispheric chemical dominance is a predisposing factor for autism.

[Recent results on the pharmacodynamics of Strychnos malgaches alkaloids].

PubMed

Rasoanaivo, P; Ratsimamanga-Urverg, S; Frappier, F

1996-01-01

Investigation of Strychnos (Loganiaceae) shrubs and trees was initiated by their traditional uses of their inherent poisons on arrows: this led to the discovery of strychnine and curare alkaloids. Subsequently, phytochemical investigation of several Strychnos species has shown great structural diversity of the alkaloid constituent which also display various biological effects, i.e. convulsive and relaxant effects on muscles, and antimicrobial, antitumor and antihypertensive properties. Ethnobotanical field work conducted in different regions of Madagascar revealed that infusion of three Strychnos species, S. mostueoides, S. myrtoides and S. diplotricha, is used in association with subcurative doses of chloroquine to treat chronic malaria. Bioassayfractionation led to the isolation of two major bioactive components, strychnobrasiline and malagashanine. Whereas strychnobrasiline is a previously known chemical compound, malagashanine is the first in a series of a new subtype of Strychnos alkaloids. These two alkaloids are devoid of intrinsic antimalarial effects, both in vitro (IC50 = 73.0 micrograms/ml for strychnobrasiline and 69.1 micrograms/ml for malagashanine) and in vivo (10 mg/kg conferred a 5% suppression of parasitemia). When these alkaloids are combined with chloroquine at doses much lower than required for antiplasmodial effects, they greatly enhance the chloroquine action in a dose dependent manner as seen by the isobologram method. Several minor alkaloids structurally related to malagashanine were also isolated from Madagascan Strychnos. They all enhance, to greater or lesser degrees, the chloroquine effectiveness. Interestingly, there is a positive correlation between the ethnomedical use of the three Strychnos species as chloroquine adjuvants and the chloroquine-potentiating effects of malagashanine and strychnobrasiline isolated from them. After preliminary toxicological studies, infusion of stem barks of S. myrtoides in association with chloroquine was successfully evaluated in a clinical setting. Additional chemical, pharmacological and toxicological work is being conducted on these alkaloids with the aim of developing purified and standardized extracts for clinical trials. These trials will be carried out in the chloroquine-resistant regions of Madagascar which are in need of inexpensive and efficient drugs for the treatment of chloroquine-resistant malaria.

Effects of D-cycloserine and aniracetam on spatial learning in rats with entorhinal cortex lesions.

PubMed

Zajaczkowski, W; Danysz, W

1997-01-01

A great body of behavioural and neurophysiological evidence suggests that excitatory amino acids are involved in mechanisms of learning and memory. Moreover, degeneration of glutamatergic pathways may underlie the cognitive deficits seen in various disorders such as Alzheimer's dementia. As direct stimulation of glutamatergic receptors with agonists may increase the risk of toxicity and accelerate neuropathological changes, a more valid approach seems to be positive modulation of glutamatergic receptors that may reverse the symptoms with a lower risk of excitotoxic effects. Such a possibility offered by partial agonists of the strychnine-insensitive glycine site of the NMDA receptor (Gly-B site) or positive modulators of AMPA receptors, such as aniracetam. In the present study, the effects of d-cycloserine and aniracetam were tested in two animal models of cognitive deficits (entorhinal cortex lesion-induced deficits evaluated in the radial maze and scopolamine-induced amnesia evaluated in passive avoidance test). D-cycloserine (6 mg/kg, for 10 days) had no effect on spatial working memory deficit induced by entorhinal cortex lesions. It did, however, reverse scopolamine-induced deficits in the passive avoidance test when given acutely at the same dose. In contrast, aniracetam (50 mg/kg, for 10 days) produced beneficial effects in the radial maze test in rats with entorhinal cortex lesions, but given at the same dose acutely did not influence scopolamine-induced amnesia. The positive effect of d-cycloserine against scopolamine-induced amnesia may be probably related to the cholinergic-glutamatergic interaction in the hippocampus. The negative data obtained with d-cycloserine in the model of entorhinal cortex lesions-induced cognitive deficits could be taken as a hint that it is probably not suitable for the symptomatological therapy of Alzheimer's disease. The mechanism of positive action of aniracetam cannot be explained on the basis of AMPA receptor modulation, as the dose used (50 mg/kg) is well below that required for the effect at AMPA receptors. Other actions such as peripheral effects or modulation of metabotropic receptors seem more likely.

Effects of pesticides on Canada Geese

USGS Publications Warehouse

Blus, L.J.; Rusch, Donald H.; Samuel, Michael D.; Humburg, Dale D.; Sullivan, Brian D.

1998-01-01

This paper summarizes published and unpublished sources relating to exposure of Canada geese (Branta canadensis) to pesticides, emphasizing documented episodes of poisoning by organochlorine (OC), organophosphorus (OP), and carbamate compounds. Canada geese accumulate the lipid-soluble OC compounds, although they have a lower potential for biomagnification of these pesticides than animals at higher trophic levels in food webs. Low residues of p,p'-DDT and its metabolite p,p'-DDE were frequently found in tissues and eggs of Canada geese, but they had no apparent adverse effects on reproductive success or eggshell thickness. Likewise, in an orchard system in central Washington state, the OC rodenticide endrin accumulated in tissues and eggs of Canada geese without apparent adverse effect. In contrast, ingestion of seeds treated with the OC heptachlor caused mortality, lowered reproductive success, and caused a local population decline of geese in Oregon and Washington. In recent years, the most persistent OC's have been banned by law and replaced with less persistent carbamate and OP compounds that do not readily accumulate in animal tissues. However, many of these compounds are acutely toxic and have caused numerous die-offs of Canada geese. Among OP compounds, diazinon was responsible for most reported die-offs (41 incidents involving >535 geese), whereas parathion applied alone or jointly with methyl parathion accounted for most reported mortalities (8 incidents involving >3,000 geese). Three other OP's, a carbamate (carbofuran), zinc phosphide, and strychnine also caused goose die-offs. Mortality from anticholinesterase (antiChE) compounds occurs relatively soon after exposure and death can usually be diagnosed by evaluation of brain cholinesterase (thE) activity. Because geese are primarily grazers, the main route of exposure to antiChE's is apparently ingestion of contaminated grasses and forbs; dermal absorption and inhalation are other routes. Despite the widespread die-offs of Canada geese from antiChE insecticides, there is no evidence of adverse effects on population levels. It is not known how sublethal antiChE exposure relates to long-term survival and reproductive success of birds.

Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

PubMed Central

Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

2016-01-01

Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%–80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and reversed when rats were pretreated with the selective H3R agonist R-(α)-methyl-histamine. Comparisons of the observed antagonistic in vitro affinities among the ligands 1–6 revealed profound stereoselectivity at human H3Rs with varying preferences for this receptor subtype. Moreover, the in vivo anticonvulsant effects observed in this study for ligands 1–6 showed stereoselectivity in different convulsion models in male adult rats. PMID:27853355

Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

PubMed

Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

2016-01-01

Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H 3 receptors (H 3 Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H 3 Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the ( S )-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide ( 1 ). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R -enantiomer, namely, ( R )-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide ( 2 ) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S -enantiomer ( 1 ), the results show that animals pretreated intraperitoneally (ip) with the R -enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier ( R )-enantiomer ( 3 ), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its ( S )-enantiomer ( 4 ) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the ( R )-enantiomer ( 3 ) in MES model were significantly greater than those of the standard H 3 R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and reversed when rats were pretreated with the selective H 3 R agonist R -(α)-methyl-histamine. Comparisons of the observed antagonistic in vitro affinities among the ligands 1 - 6 revealed profound stereoselectivity at human H 3 Rs with varying preferences for this receptor subtype. Moreover, the in vivo anticonvulsant effects observed in this study for ligands 1 - 6 showed stereoselectivity in different convulsion models in male adult rats.

Kynurenic acid analogues with improved affinity and selectivity for the glycine site on the N-methyl-D-aspartate receptor from rat brain.

PubMed

Foster, A C; Kemp, J A; Leeson, P D; Grimwood, S; Donald, A E; Marshall, G R; Priestley, T; Smith, J D; Carling, R W

1992-05-01

The glycine site on the N-methyl-D-aspartate (NMDA) subtype of receptors for the excitatory neurotransmitter glutamate is a potential target for the development of neuroprotective drugs. We report here two chemical series of glycine site antagonists derived from kynurenic acid (KYNA), with greatly improved potency and selectivity. Disubstitution with chlorine or bromine in the 5- and 7-positions of KYNA increased affinity for [3H]glycine binding sites in rat cortex/hippocampus P2 membranes, with a parallel increase of potency for antagonism of NMDA-evoked responses in the rat cortical wedge preparation. The optimal compound was 5-I,7-Cl-KYNA, with an IC50 for [3H]glycine binding of 29 nM and an apparent Kb in the cortical wedge preparation of 0.41 microM. Reduction of the right-hand ring of 5,7-diCl-KYNA reduced affinity by 10-fold, but this was restored by substitution in the 4-position with the trans-phenylamide and further improved in the trans-benzylamide. The optimal compound was the transphenylurea (L-689,560), with an IC50 of 7.4 nM and an apparent Kb of 0.13 microM. Both series of compounds displayed a high degree of selectivity for the glycine site, having IC50 values of greater than 10 microM versus radioligand binding to the glutamate recognition sites of NMDA, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and kainate receptors and the strychnine-sensitive glycine receptor. Selectivity versus AMPA receptor-mediated responses was also apparent in the rat cortical wedge and in patch-clamp recordings of cortical neurons in culture. Experiments using [3H]dizocilpine (MK-801) binding indicated that 5,7-diBr-KYNA, 5,7-diCl-KYNA, 5-I,7-Cl-KYNA, and L-689,560 all behaved as full antagonists and were competitive with glycine. Patch-clamp recordings of cortical neurons in culture also indicated that NMDA-induced currents were antagonized by competition for the glycine site, and gave no evidence for partial agonist activity. pKi values for 5,7-diBr-KYNA and L-689,560 in these experiments were 7.2 and 7.98, respectively, similar to the affinities of these compounds in the glycine binding assay. The high affinity and selectivity of these new derivatives make them useful tools to investigate the function of the glycine site on the NMDA receptor.