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Sample records for pyridinealdoxime methiodide pam-type

  1. Blood-brain barrier penetration of novel pyridinealdoxime methiodide (PAM)-type oximes examined by brain microdialysis with LC-MS/MS

    SciTech Connect

    Okuno, Sou; Sakurada, Koichi Ohta, Hikoto; Ikegaya, Hiroshi; Kazui, Yuko; Akutsu, Tomoko; Takatori, Takehiko; Iwadate, Kimiharu

    2008-02-15

    To develop a new reactivator of inhibited acetylcholinesterase (AChE) that can easily penetrate the blood-brain barrier (BBB), BBB penetration of 6 known and novel pyridinealdoxime methiodide (PAM)-type oximes (alkylPAMs) with relatively high reactivation activities was examined by in vivo rat brain microdialysis with liquid chromatography-mass spectrometry (LC-MS/MS). The 50% lethal dose (LD{sub 50}) of alkylPAMs was intravenously determined for Wistar rats, then the limit of detection, quantification range and linearity of the calibration curve of the alkylPAMs in dialysate and blood were determined by LC-MS/MS. Following 10% LD{sub 50} intravenous administration of the alkylPAMs, 4-[(hydroxyimino) methyl]-1-(2-phenylethyl) pyridinium bromide (4-PAPE) and 4-[(hydroxyimino) methyl]-1-octylpyridinium bromide (4-PAO) appeared in the dialysate. Striatal extracellular fluid/blood concentration ratios were 0.039 {+-} 0.018 and 0.301 {+-} 0.183 (mean {+-} SEM), respectively, 1 h after treatment. This is the first report of BBB penetration of 4-PAPE, and the concentration ratio was smaller than that of 2-PAM.The mean BBB penetration of 4-PAO was approximately 30%, indicating that intravenous administration of 4-PAO may be effective for the reactivation of blocked cholinesterase in the brain. However, the toxicity of 4-PAO (LD{sub 50}; 8.89 mg/kg) was greater than that of 2-PAM. Further investigation is required to determine the effects of these alkylPAMs in organophosphate poisoning.

  2. Intravenous kinetics and metabolism of [15,16-3H]naltrexonium methiodide in the rat.

    PubMed

    Misra, A L; Pontani, R B; Vadlamani, N L

    1987-03-01

    After a 4 mg kg-1 bolus intravenous dose of [15,16-3H]naltrexonium methiodide to the rat, brain to plasma concentration ratios of the compound were 0.031 to 0.228 between 0.25 to 6 h after injection and the t 1/2 beta in plasma and brain were 2.92 and 7.61 h, respectively. Ethyl acetate-extracted radioactivity due to metabolites in plasma decayed with t 1/2 beta 1.83 h and the ratios of plasma concentration of metabolites to quaternary compound between 0.25 and 6 h were 0.014-0.026. Only unconjugated 7,8-dihydro-14-hydroxynormorphine, naltrexone and traces of 7,8-dihydro-14-hydroxynormorphinone were the metabolites in plasma. Naltrexone (but not normetabolites) was present only in traces in brain up to 0.5 h after injection and not at later times. PMID:2883290

  3. Steroids and related studies, part 66: crystal and molecular structure of 17a-(2-acetoxyethyl)-17a-aza-D-homo-5-androsten-3. beta. -yl-acetate methiodide (HS465), a monoquaternary azasteroid incorporating an acetylcholine-like moiety

    SciTech Connect

    Chattopadhyay, T.K.; Palmer, R.A.; Singh, H.; Paul, D.

    1986-04-01

    The crystal structure of a synthetic monoquaternary azasteroid containing an acetylcholine-like moiety, 17a-(2-acetoxyethyl)-17a-aza-D-homo-5 androsten-3..beta..-yl-acetate methiodide (HS465) (C/sub 26/H/sub 42/NO/sub 4/)/sup +/I/sup -/, has been determined by the heavy-atom method and refined by full-matrix least squares to R = 0.0410 for 2462 reflections, using MoK..cap alpha.. radiation (lambda = 0.7114 A). The crystals are monoclinic: P2/sub 1/, a = 15.244(4), b = 9.009(6), c = 9.886(3) A, ..beta.. = 104.26/sup 0/(3), Z = 2. Rings A and C have distorted-chair conformations, ring D-homo is a symmetrical chair, and ring B is a half-chair. The acetoxyethyl side-group appended to N(17a) simulates an acetylcholine-like moiety, and exhibits a conformation similar to that frequently adopted by acetylcholine itself in the presence of heavy anions.

  4. Antibacterial and antifungal activity of liriodenine and related oxoaporphine alkaloids.

    PubMed

    Hufford, C D; Sharma, A S; Oguntimein, B O

    1980-10-01

    Liriodenine was evaluated for its antibacterial and antifungal activity against several microorganisms. Other related oxoaporphine alkaloids also were evaluated. Attempts to prepare oxoaporphine alkaloids from N-acetylnoraporphines were unsuccessful, but an unexpected phenanthrene alkaloid was obtained. A novel N-demethylation reaction was noted when oxogaucine methiodide and liriodenine methiodide were treated with alumina. PMID:7420287

  5. Bridged bicyclic systems as acetylcholinesterase reactivators and pretreatment drugs. Annual report, 15 July 1988-14 July 1989

    SciTech Connect

    Moriarty, R.M.

    1990-03-30

    During the past year a large number substituted carbamates, thiocarbamates of various bridged aza bicyclic oximes and their methiodides and meth chlorides have been synthesized. Among these are: (i) O-(N-Substituted carbamoyl)-3-tropinone oxime methiodides and methchlorides, (ii) 0-(N-Substituted carbamoyl)-6-cyano trop-3-ene-2-one oxime methiodides, (iii) O-N-(2`,3`,4`, 6`-Tetra-0-acetyl- b-D-glucopyranosyl thiocarbamoyl)-3-tropinone oxime and its methiodide. Synthesis of 1,6-bis-N`,N`-dimethyl- 3`-oximino-0-carbamoyl tropanonium-N-y1 hexane diiodide and 2,5- bis-(N`N`-dimethyl- 3`-oximino-0-carbamoyl tropanonium-N-yl)-toluene diiodide have been achieved. From phencyclidine a series 4-phenyl-4-0-(N-substituted carbamoyl)-4`-piperidone oxime-1`-yl-1-methyl piperidone methiodides have been synthesized. Syntheses of 0-(N-substituted carbamoyl)-3-exo-dimethyl aminomethyl2-norbornone oximes and their methiodides have been accomplished.

  6. Pretreatment drugs against organophosphorus agents based on azabicyclic n-alkyl oximino o-carbamates. Annual report, 24 September 1990-23 September 1991

    SciTech Connect

    Moriarty, R.M.

    1991-11-12

    During the past year, a number of purely carbocyclic norbonanone derived oximino carbamates and their methiodide salts have been synthesized and submitted for biological evaluation as pretreatment agents against organophosphorus agents. Additionally, a synthetic route has been devised and employed for the preparation of 2-tropinone, a key precursor for the synthesis of structurally important oximino carbamate derivatives.

  7. Naloxone improves functional recovery of myocardial stunning in conscious dogs through its action on the central nervous system.

    PubMed

    Weber, T P; Stypmann, J; Meissner, A; Hartlage, M G; Van Aken, H; Rolf, N

    2001-04-01

    This study tests the hypothesis that naloxone, but not its quarternary salt, naloxone methiodide (which does not enter the central nervous system), improves recovery from myocardial stunning in conscious dogs. Twenty dogs were chronically instrumented for measurement of heart rate, left atrial, aortic and left ventricular pressure (LVP), LV dP x dtmax(-1) and myocardial wall thickening fraction (WTF). Regional myocardial blood flow was determined with coloured microspheres. Occluder around the left anterior descending artery (LAD) allowed induction of reversible LAD ischaemia. Each of the 20 dogs underwent two LAD ischaemic challenges. Experiments (performed on separate days, in crossover fashion) were: (i) 10 min of LAD occlusion after application of naloxone 63 microg kg(-1) or naloxone methiodide 63 microg kg(-1) and (ii) occlusion without naloxone or naloxone methiodide. WTF was measured at baseline and until complete recovery occurred. LAD ischaemia significantly reduced LAD WTF with (mean (SD) 54 (15)% lower than baseline) and without naloxone (55 (16)% lower than baseline), without significant haemodynamic differences. Between I to 30 min of reperfusion, WTF was significantly higher with naloxone (P < 0.05). There was no difference in WTF with or without naloxone methiodide. We conclude that naloxone improved recovery from myocardial stunning in conscious dogs, and that this was centrally mediated. PMID:11573630

  8. catena-Poly[[[bis­(4-pyridine­aldoxime-κN 1)zinc]-μ-benzene-1,4-dicarboxyl­ato-κ2 O 1:O 4] 4-pyridine­aldoxime monosolvate

    PubMed Central

    Kumagai, Hitoshi; Kawata, Satoshi; Sakamoto, Yoshiyuki

    2013-01-01

    In the title compound, {[Zn(C8H4O4)(C6H6N2O)2]·C6H6N2O}n, the ZnII ion exhibits a tetra­hedral coordination environment defined by two benzene-1,4-dicarboxylate dianions and two 4-pyridinealdoxime ligands. The dianions bridge the ZnII ions, giving a zigzag chain along the b axis. Adjacent chains are connected by O—H⋯O hydrogen bonds, forming a cavity in which an uncoordinating 4-pyridine­aldoxime mol­ecule is located; this mol­ecule is linked by O—H⋯O and O—H⋯N hydrogen bonds to the zigzag chain. PMID:23634010

  9. Oxoaporphine alkaloids: conversion of lysicamine into liriodendronine and its 2-O-methyl ether, and antifungal activity.

    PubMed

    Pabuccuoglu, V; Rozwadowska, M D; Brossi, A; Clark, A; Hufford, C D; George, C; Flippen-Anderson, J L

    1991-01-01

    Pschorr reaction of diazonium salt 7 in aqueous methanolic sulfuric acid afforded, besides lysicamine 2, the orange colored sulfate of oxodibenzopyrrocoline (8). The structure is fully supported by an X-ray analysis of its picrate salt. Selective ether cleavage of lysicamine (2) with 48% HBr afforded a hydrobromide of 9, and free betaine 9 on treatment with pyridine-water. Both compounds methylated on treatment with etherial diazomethane on nitrogen to give the known 2-O,N-dimethylliriodendronine (11). Liriodendronine (10) was obtained from lysicamine (2) on heating with pyridine HBr at 189 degrees C, and treatment with pyridine-water, as a dark violet betaine. Betaine 12 was obtained by heating 11.HCl to 200 degrees C. The quaternary salts of lysicamine, lysicamine methiodide (3) and lysicamine methosulfate (4) were comparable in anticandidal activity to liriodenine (1), but were not as active as liriodenine methiodide (13). PMID:2043039

  10. GABAA Receptor Blockade Enhances Memory Consolidation by Increasing Hippocampal BDNF Levels

    PubMed Central

    Kim, Dong Hyun; Kim, Jong Min; Park, Se Jin; Cai, Mudan; Liu, Xiaotong; Lee, Seungheon; Shin, Chan Young; Ryu, Jong Hoon

    2012-01-01

    Memory consolidation is the process by which acquired information is converted to something concrete to be retrieved later. Here we examined a potential role for brain-derived neurotrophic factor (BDNF) in mediating the enhanced memory consolidation induced by the GABAA receptor antagonist, bicuculline methiodide. With the administration of an acquisition trial in naïve mice using a passive avoidance task, mature BDNF (mBDNF) levels were temporally changed in the hippocampal CA1 region, and the lowest levels were observed 9 h after the acquisition trial. In the passive avoidance task, bicuculline methiodide administration within 1 h of training but not after 3 h significantly increased latency time in the retention trial 24 h after the acquisition trial. Concomitantly, 1 h post-training administration of bicuculline methiodide, which enhanced memory consolidation, significantly increased mBDNF levels 9 h after training compared to those of the vehicle-treated control group. In addition, exogenous human recombinant BDNF (hrBDNF) administration 9 h after training into the hippocampal CA1 region facilitated memory consolidation confirming that the increase in mBDNF at around 9 h after training plays a key role in the enhancement of memory consolidation. Moreover, the increases in latency time and immediate early gene expressions by bicuculline methiodide or hrBDNF were significantly blocked by anisomycin, a protein synthesis inhibitor, K252a, a tyrosine receptor kinase (Trk) inhibitor, or anti-TrkB IgG. These findings suggest that the increase in the level of mBDNF and its function during a restricted time window after training are required for the enhancement of memory consolidation by GABAA receptor blockade. PMID:21900885

  11. Aporphine metho salts as neuronal nicotinic acetylcholine receptor blockers.

    PubMed

    Iturriaga-Vásquez, Patricio; Pérez, Edwin G; Slater, E Yvonne; Bermúdez, Isabel; Cassels, Bruce K

    2007-05-15

    (S)-Aporphine metho salts with the 1,2,9,10 oxygenation pattern displaced radioligands from recombinant human alpha7 and alpha4beta2 neuronal nicotinic acetylcholine receptors (nAChR) at low micromolar concentrations. The affinity of the nonphenolic glaucine methiodide (4) (vs [(3)H]cytisine) was the lowest at alpha4beta2 nAChR (K(i)=10 microM), and predicentrine methiodide (2) and xanthoplanine iodide (3), with free hydroxyl groups at C-2 or C-9, respectively, had the highest affinity at these receptors (K(i) approximately 1 microM), while the affinity of the diphenolic boldine methiodide (1) was intermediate between these values. At homomeric alpha7 nAChR, xanthoplanine had the highest affinity (K(i)=10 microM) vs [(125)I]alpha-bungarotoxin while the other three compounds displaced the radioligand with K(i) values between 15 and 21 microM. At 100 microM, all four compounds inhibited the responses of these receptors to EC(50) concentrations of ACh. The effects of xanthoplanine iodide (3) were studied in more detail. Xanthoplanine fully inhibited the EC(50) ACh responses of both alpha7 and alpha4beta2 nACh receptors with estimated IC(50) values of 9+/-3 microM (alpha7) and 5+/-0.8 microM (alpha4beta2). PMID:17391965

  12. Involvement of peripheral mu opioid receptors in scratching behavior in mice.

    PubMed

    Yamamoto, Atsuki; Sugimoto, Yukio

    2010-12-15

    Pruritus is a common adverse effect of opioid treatment. However, the mechanism by which pruritus is induced by opioid administration is unclear. In this study, we examined the effects of the intradermal injection of loperamide, a peripherally restricted opioid receptor agonist, on the itch sensation. When injected intradermally into the rostral part of the back in mice, loperamide elicited scratching behavior. We also examined the effects of the selective mu opioid receptor agonist [d-Ala², N-Me-Phe⁴, Gly⁵-ol]-enkephalin acetate (DAMGO), the selective delta opioid receptor agonist [d-Pen(2,5)]-enkephalin (DPDPE), and the selective kappa opioid receptor agonist U-50488H on scratching behavior in mice in order to determine which subtype is involved in opioid-induced pruritus. Following intradermal injection into the rostral part of the back in mice, DAMGO elicited scratching behavior, while DPDPE and U-50488H did not. This suggests that peripheral mu opioid activation elicits the itch sensation. Next, we focused on the treatment of opioid-induced itch sensation without central adverse effects. Naloxone methiodide is a peripherally restricted opioid receptor antagonist. In the present study, naloxone methiodide significantly suppressed scratching behavior induced by loperamide and DAMGO. These findings suggest that mu opioid receptors play a primary role in peripheral pruritus and that naloxone methiodide may represent a possible remedy for opioid-induced itching. PMID:20863827

  13. Differences in the morphine-induced inhibition of small and large intestinal transit: Involvement of central and peripheral μ-opioid receptors in mice.

    PubMed

    Matsumoto, Kenjiro; Umemoto, Hiroyuki; Mori, Tomohisa; Akatsu, Ryuya; Saito, Shinichiro; Tashima, Kimihito; Shibasaki, Masahiro; Kato, Shinichi; Suzuki, Tsutomu; Horie, Syunji

    2016-01-15

    Constipation is the most common side effect of morphine. Morphine acts centrally and on peripheral sites within the enteric nervous system. There are a few comprehensive studies on morphine-induced constipation in the small and large intestine by the activation of central and peripheral μ-opioid receptors. We investigated the differences in the inhibition of the small and large intestinal transit in normal and morphine-tolerant mice. Morphine reduced the geometric center in the fluorescein isothiocyanate-dextran assay and prolonged the bead expulsion time in a dose-dependent manner. The inhibitory effects of morphine were blocked by μ-opioid antagonist β-funaltrexamine, but not by δ- and κ-opioid antagonists. The peripheral opioid receptor antagonist, naloxone methiodide, partially blocked morphine's effect in the small intestine and completely blocked its effect in the large intestine. The intracerebroventricular administration of naloxone significantly reversed the delay of small intestinal transit but did not affect morphine-induced inhibition of large intestinal transit. Naloxone methiodide completely reversed the inhibition of large intestinal transit in normal and morphine-tolerant mice. Naloxone methiodide partially reversed the morphine-induced inhibition of small intestinal transit in normal mice but completely reversed the effects of morphine in tolerant mice. Chronic treatment with morphine results in tolerance to its inhibitory effect on field-stimulated contraction in the isolated small intestine but not in the large intestine. These results suggest that peripheral and central opioid receptors are involved in morphine-induced constipation in the small and large intestine during the early stage of treatment, but the peripheral receptors mainly regulate constipation during long-term morphine treatment. PMID:26712376

  14. Pilocarpine modulates the cellular electrical properties of mammalian hearts by activating a cardiac M3 receptor and a K+ current

    PubMed Central

    Wang, Huizhen; Shi, Hong; Lu, Yanjie; Yang, Baofeng; Wang, Zhiguo

    1999-01-01

    Pilocarpine, a muscarinic acetylcholine receptor (mAChR) agonist, is widely used for treatment of xerostomia and glaucoma. It can also cause many other cellular responses by activating different subtypes of mAChRs in different tissues. However, the potential role of pilocarpine in modulating cardiac function remained unstudied.We found that pilocarpine produced concentration-dependent (0.1–10 μM) decrease in sinus rhythm and action potential duration, and hyperpolarization of membrane potential in guinea-pig hearts. The effects were nearly completely reversed by 1 μM atropine or 2 nM 4DAMP methiodide (an M3-selective antagonist).Patch-clamp recordings in dispersed myocytes from guinea-pig and canine atria revealed that pilocarpine induces a novel K+ current with delayed rectifying properties. The current was suppressed by low concentrations of M3-selective antagonists 4DAMP methiodide (2–10 nM), 4DAMP mustard (4–20 nM, an ackylating agent) and p-F-HHSiD (20–200 nM). Antagonists towards other subtypes (M1, M2 or M4) all failed to alter the current.The affinity of pilocarpine (KD) at mAChRs derived from displacement binding of [3H]-NMS in the homogenates from dog atria was 2.2 μM (65% of the total binding) and that of 4DAMP methiodide was 2.8 nM (70% of total binding), consistent with the concentration of pilocarpine needed for the current induction and for the modulation of the cardiac electrical activity and the concentration of 4DAMP to block pilocarpine effects.Our data indicate, for the first time, that pilocarpine modulates the cellular electrical properties of the hearts, likely by activating a K+ current mediated by M3 receptors. PMID:10372814

  15. Abiotic transformations and decomposition kinetics of 4-carbamoyl-2'-[(hydroxyimino)methyl]-1,1'-(oxydimethylene)-bis(pyridin ium chloride) in aqueous phosphate buffers.

    PubMed

    Mdachi, R E; Marshall, W D; Ecobichon, D J; Fouad, F M; Connolley-Mendoza, C E

    1990-01-01

    The rate of disappearance of 4-carbamoyl-2'-[(hydroxyimino)methyl]-1,1'-(oxydimethylene) bis (pyridinium chloride) (HI-6) from aqueous phosphate buffers (pH 3.0-9.1) was both pH and temperature sensitive. In midrange buffers (pH 6.0-9.1, mu = 0.2 M) at 37, 25, or 4 degrees C the decomposition followed first-order kinetics consistent with hydroxide-promoted decomposition of the un-ionized drug or with hydrolysis of the ionized oxime anion to result in 4-carbamoyl-2'-hydroxy-1,1'-(oxydimethylene)bis(pyridinium) cation (intermediate 1). The subsequent conversion of intermediate 1 to 4-carboxy-2'-hydroxy-1,1'-(oxydimethylene)bis(pyridinium) cation (intermediate 2) followed higher order kinetics which were consistent with either acid- or base-promoted hydrolysis of the B-ring amide functionality. After approximately 138 days in the dark, the sum of the residual HI-6, intermediate 1, and intermediate 2 in the crude decomposition mixture accounted for 89.9 +/- 10.0% of the initial substrate. Minor byproducts included 4-carbamoyl-2'-carboxy-1,1'-(oxydimethylene)bis(pyridinium) cation, 2-pyridinealdoxime, 2-pyridinecarboxaldehyde, 2-hydroxypyridine, isonicotinamide, isonicotinic acid, and traces of cyanide. In addition, 2-cyanopyridine appeared to be a transient intermediate in more alkaline media. In total, this drug resembles other mono- and bis(pyridinium) aldoximes in terms of the decomposition routes in aqueous solutions at intermediate pHs. PMID:2133092

  16. The pharmacology of the cholinoceptor in muscle preparations of Ascaris lumbricoides var. suum

    PubMed Central

    Natoff, I. L.

    1969-01-01

    1. The preparation of a muscle strip of Ascaris lumbricoides for the study of the effect of drugs in vitro is described. 2. Stimulant drugs which are classified as nicotine-like in mammalian pharmacology increased the isometric tension of this preparation. These drugs were, in descending order of potency: dimethylphenylpiperazinium, nicotine, acetylcholine, carbachol, decamethonium and pyridine-2-aldoxime methiodide. 3. Muscarine-like drugs (oxotremorine, methacholine, pilocarpine) had no activity. 4. Potassium and barium ions stimulated the tissue, while the anti-cholinesterases, dichlorvos and eserine, increased the resting tension of the preparation and potentiated the responses to acetylcholine. 5. Adrenaline neither stimulated the tissue nor affected the responses to nicotine-like drugs. 6. The relative potency of several blocking agents which antagonize the responses to nicotine-like drugs was assayed. These blocking agents were, in descending order of potency: mecamylamine, (+)-tubocurarine, hexamethonium, atropine and piperazine. Acetylcholine, dimethylphenylpiperazinium and pyridine-2-aldoxime methiodide apparently act on a common receptor, for each blocking agent had a similar molar inhibitory concentration against these stimulants. 7. It is concluded that the cholinoceptor in muscle preparations of Ascaris lumbricoides is pharmacologically similar to that of the mammalian autonomic ganglion. PMID:4390485

  17. Cooperative metal-ligand assisted E/Z isomerization and cyano activation at Cu(II) and Co(II) complexes of arylhydrazones of active methylene nitriles.

    PubMed

    Mahmudov, Kamran T; Kopylovich, Maximilian N; Sabbatini, Alessandra; Drew, Michael G B; Martins, Luísa M D R S; Pettinari, Claudio; Pombeiro, Armando J L

    2014-09-15

    New (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene)hydrazinyl)benzoic acid (H2L(4)) and known sodium 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonate (NaHL(1)), 2-(2-(dicyano-methylene)hydrazinyl)benzoic acid (H2L(2)), and sodium (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene)hydrazinyl)benzenesulfonate (NaHL(3)) were used in the template synthesis of a series of Cu(II) and Co(II) complexes [Cu(H2O)2L(1a)]·H2O (1), [Cu(H2O)(3-pyon)L(1b)]·H2O (2), [Cu(H2O)(4-pyon)L(1b)] (3), [Co(H2O)((CH3)2NCHO)(μ-L(2a))]2·(CH3)2NCHO (4), [Cu3(μ3-OH)(NO3)(CH3OH)(μ2-X)3(μ2-HL(3))] (5), [Cu(H2O)(py)L(3)]·H2O (6), [Cu(H2O)2(μ-L(4))]6·6H2O (7), [Cu(2-cnpy(b))2(L(1b))2]·2H2O (8), [Cu(2-cnpy(a))2(L(1a))2]·2H2O (9), and [Cu(H2O)(4-cnpy)(L(1a))2] (10), where 3-pyon = 1-(pyridin-3-yl)ethanone, 4-pyon = 1-(pyridin-4-yl)ethanone, py = pyridine, HX = syn-2-pyridinealdoxime, 4-cnpy = 4-cyanopyridine; 2-cnpy(a), 2-cnpy(b), L(1a), L(1b), L(2a) are the ligands derived from nucleophilic attack of methanol (a) or water (b) on a cyano group of 2-cyanopyridine (2-cnpy), L(1) or L(2), respectively, giving the corresponding iminoesters (2-cnpy(a), L(1a) or L(2a)) or carboxamides (2-cnpy(b) or L(1b)). An auxiliary ligand, namely syn-2-pyridinealdoxime or pyridine, acting cooperatively with the metal ion (Cu(II) in this case), induced an E/Z isomerization of the H2L(4) ligand; the E- and Z-isomers were isolated separately and fully characterized (compounds 9 and 10, respectively). A one-pot activation of nitrile groups in different molecules was achieved in the syntheses of 8 and 9. Complexes 1-10 are catalyst precursors for the solvent-free microwave (MW)-assisted selective oxidation of secondary alcohols to the corresponding ketones, with typical yields in the 29-99% range (TOFs up to 4.94 × 10(3) h(-1)) after 30 min of MW irradiation. PMID:25148569

  18. Evidence That GABA Mediates Dopaminergic and Serotonergic Pathways Associated with Locomotor Activity in Juvenile Chinook Salmon (Oncorhynchus tshawytscha)

    USGS Publications Warehouse

    Clements, S.; Schreck, C.B.

    2004-01-01

    The authors examined the control of locomotor activity in juvenile salmon (Oncorhynchus tshawytscha) by manipulating 3 neurotransmitter systems-gamma-amino-n-butyric acid (GABA), dopamine, and serotonin-as well as the neuropeptide corticotropin releasing hormone (CRH). Intracerebroventricular (ICV) injections of CRH and the GABAAagonist muscimol stimulated locomotor activity. The effect of muscimol was attenuated by administration of a dopamine receptor antagonist, haloperidol. Conversely, the administration of a dopamine uptake inhibitor (4???,4??? -difluoro-3-alpha-[diphenylmethoxy] tropane hydrochloride [DUI]) potentiated the effect of muscimol. They found no evidence that CRH-induced hyperactivity is mediated by dopaminergic systems following concurrent injections of haloperidol or DUI with CRH. Administration of muscimol either had no effect or attenuated the locomotor response to concurrent injections of CRH and fluoxetine, whereas the GABAA antagonist bicuculline methiodide potentiated the effect of CRH and fluoxetine.

  19. Effects of a 60 Hz magnetic field on central cholinergic systems of the rat

    SciTech Connect

    Lai, H.; Carino, M.A.; Horita, A.; Guy, A.W. )

    1993-03-15

    The authors studied the effects of an acute exposure to a 60 Hz magnetic field on sodium-dependent, high-affinity choline uptake in the brain of the rat. Decreases in uptake were observed in the frontal cortex and hippocampus after the animals were exposed to a magnetic field at flux densities [>=] 0.75 mT. These effects of the magnetic field were blocked by pretreating the animals with the narcotic antagonist naltrexone, but not by the peripheral opioid antagonist, naloxone methiodide. These data indicate that the magnetic-field-induced decreases in high-affinity choline uptake in the rat brain were mediated by endogenous opioids in the central nervous systems.

  20. Clinical observation and comparison of the effectiveness of several oxime cholinesterase reactivators.

    PubMed

    Xue, S Z; Ding, X J; Ding, Y

    1985-01-01

    After passing toxicity and experimental therapeutic tests, four oxime cholinesterase reactivators [PAM (pyridine aldoxime methiodide), PAC (pralidoxime, pyridine aldoxime methylchloride), TMB4 (trimedoxime), and DMO4 (obidoxime, Toxogonin, LüH6)] were compared in clinical trials. All of them proved capable of restoring erythrocyte cholinesterase activity and relieving symptoms and signs of organophosphate insecticide poisoning. Mildly and moderately poisoned patients can be treated by several injections of any one of these drugs alone, but severe cases need the synergistic action of atropine, as well as treatments for two to three consecutive days. Although response to treatment is stronger with TMB4 and DMO4, they are not recommended for routine treatment because of their dangerous adverse side effects. PMID:3914075

  1. A comparison of affinity constants for muscarine-sensitive acetylcholine receptors in guinea-pig atrial pacemaker cells at 29 degrees C and in ileum at 29 degrees C and 37 degrees C.

    PubMed Central

    Barlow, R B; Berry, K J; Glenton, P A; Nilolaou, N M; Soh, K S

    1976-01-01

    1 The affinity of 17 compounds for muscarine-sensitive acetylcholine receptors in atrial pacemaker cells and ileum of the guinea-pig has been measured at 29 degrees C in Ringer-Locke solution. Measurements were also made at 37 degrees C with 7 of them. 2 Some of the compounds had much higher affinity for the receptors in the ileum than for those in the atria. For the most selective compound, 4-diphenylacetoxy-N-methylpiperidine methiodide, the difference was approximately 20-fold. The receptors in the atria are therefore different the structure from those in the ileum. 3 The effect of temperature on affinity are not the same for all the compounds, tested indicating different enthalpies and entropies of adsorption and accounting for some of the difficulty experienced in predicting the affinity of new compounds. PMID:1000135

  2. Antiradiation compounds. 20. 1-Methylquinolinium(and pyridinium)-2-dithioacetic acid derivatives

    SciTech Connect

    Foye, W.O.; Jones, R.W.; Ghoshal, P.K.; Almassian, B.

    1987-01-01

    A new class of radiation-protective compounds has been found in the bis(methylthio) and methylthio amino derivatives of 1-methylquinolinium- and 1-methylpyridinium-2-dithioacetic acids. The compounds gave good protection to mice vs. 1000-rad gamma-radiation in ip doses of 10 mg/kg or less, much lower than those required for the aminoalkyl thiols (approximately 150-600 mg/kg). The dithioacetic acid zwitterions were prepared from the base-catalyzed reaction of carbon disulfide with quinaldine and picoline methiodides, and the bis(methylthio) derivatives resulted from reaction with methyl iodide at room temperature. Replacement of one methylthio moiety took place readily on reaction of the bis(methylthio) derivatives with 1 molar equiv of an amine. The best protective activity was found with the methylthio piperidino derivative in both the quinolinium and pyridinium series.

  3. Antiradiation compounds. XXII. Methyl 3-amino-2-phenyldithiopropenoates and 1,1-bis(methylthio)-3-amino-2-phenyl-1-propenes

    SciTech Connect

    Foye, W.O.; Jones, R.W.; Ghoshal, P.K.

    1987-10-01

    The title compounds were prepared in the attempt to provide methylthio and bis(methylthio) analogues of the radioprotective pyridinium- and quinolinium-2-dithioacetic acid derivatives in which the methylthio function is attached to an amino group through an aliphatic chain. The methyl 3-amino-2-phenyldithiopropenoates were obtained by the reaction of amines with 4-phenyl-3-methylthio-1,2-dithiolium iodide, and the 1,1-bis(methylthio)-3-amino-2-phenyl-1-propenes were obtained by methylation and reduction of the dithiopropenoates. The methyl dithiopropenoates with aliphatic substituents on the nitrogen gave only fair or poor radiation protection in mice, and one example of the reduced bis(methylthio) derivatives tested was inactive. The precursor 1,2-dithiole-3-thione and its methiodide, predicted to be radiation protective, were found inactive in this test.

  4. Plasmodium falciparum: growth response to potassium channel blocking compounds.

    PubMed

    Waller, Karena L; Kim, Kami; McDonald, Thomas V

    2008-11-01

    Potassium channels are essential for cell survival and regulate the cell membrane potential and electrochemical gradient. During its lifecycle, Plasmodium falciparum parasites must rapidly adapt to dramatically variant ionic conditions within the mosquito mid-gut, the hepatocyte and red blood cell (RBC) cytosols, and the human circulatory system. To probe the participation of K(+) channels in parasite viability, growth response assays were performed in which asexual stage P. falciparum parasites were cultured in the presence of various Ca(2+)-activated K(+) channel blocking compounds. These data describe the novel anti-malarial effects of bicuculline methiodide and tubocurarine chloride and the novel lack of effect of apamine and verruculogen. Taken together, the data herein imply the presence of K(+) channels, or other parasite-specific targets, in P. falciparum-infected RBCs that are sensitive to blockade with Ca(2+)-activated K(+) channel blocking compounds. PMID:18703053

  5. Activation of peripheral delta opioid receptors eliminates cardiac electrical instability in a rat model of post-infarction cardiosclerosis via mitochondrial ATP-dependent K+ channels.

    PubMed

    Maslov, L N; Lishmanov, Yu B; Solenkova, N V; Gross, G J; Stefano, G B; Tam, S W

    2003-07-01

    The effects of the selective delta-1 (delta(1)) opioid receptor agonist, DPDPE, and the selective delta(2) opioid receptor agonist, DSLET, have been studied on the ventricular fibrillation threshold (VFT) in rats with an experimental post-infarction cardiosclerosis (CS). It has been found that CS induced a significant decrease in VFT. This CS-induced decrease in VFT was significantly reversed by intravenous administration of DPDPE (0.1 mg/kg) 10 min before VFT measurement. On the contrary, intravenous injection of DSLET (0.5 mg/kg) exacerbated the CS-induced cardiac electrical instability. Pretreatment with the selective delta opioid receptor antagonist, ICI 174,864 (0.5 mg/kg), completely abolished the changes in VFT produced by both DPDPE and DSLET. Previous administration of a nonselective peripherally acting opioid receptor antagonist, naloxone methiodide (5 mg/kg) also completely reversed the antifibrillatory action of DPDPE. Naloxone methiodide and ICI 174,864 alone had no effect on VFT. Pretreatment with the nonselective K(ATP) channel blocker, glibenclamide (0.3 mg/kg), or with the mitochondrial selective K(ATP) channel blocker, 5-hydroxydecanoic acid (5-HD, 5 mg/kg), completely abolished the DPDPE-induced increase in cardiac electrical stability. Glibenclamide and 5-HD alone had no effect on VFT. These results demonstrate that the delta opioid receptor plays an important role in the regulation of electrical stability in rats with post-infarction cardiosclerosis. We propose that peripheral delta(1) opioid receptor stimulation reverses CS-induced electrical instability via mitochondrial K(ATP) channels. On the contrary, delta(2) opioid receptor stimulation may exacerbate the CS-induced decrease in VFT. Further studies are necessary to determine the delta opioid receptor subtype which mediates the antifibrillatory effect of DPDPE and pro-fibrillatory effect of DSLET. PMID:12798419

  6. Hypoxia-induced hypothermia mediated by GABA in the rostral parapyramidal area of the medulla oblongata.

    PubMed

    Osaka, T

    2014-05-16

    Hypoxia evokes a regulated decrease in the body core temperature (Tc) in a variety of animals. The neuronal mechanisms of this response include, at least in part, glutamatergic activation in the lateral preoptic area (LPO) of the hypothalamus. As the sympathetic premotor neurons in the medulla oblongata constitute a cardinal relay station in the descending neuronal pathway from the hypothalamus for thermoregulation, their inhibition can also be critically involved in the mechanisms of the hypoxia-induced hypothermia. Here, I examined the hypothesis that hypoxia-induced hypothermia is mediated by glutamate-responsive neurons in the LPO that activate GABAergic transmission in the rostral raphe pallidus (rRPa) and neighboring parapyramidal region (PPy) of the medulla oblongata in urethane-chloralose-anesthetized, neuromuscularly blocked, artificially ventilated rats. Unilateral microinjection of GABA (15nmol) into the rRPa and PPy regions elicited a prompt increase in tail skin temperature (Ts) and decreases in Tc, oxygen consumption rate (VO2), and heart rate. Next, when the GABAA receptor blocker bicuculline methiodide (bicuculline methiodide (BMI), 10pmol) alone was microinjected into the rRPa, it elicited unexpected contradictory responses: simultaneous increases in Ts, VO2 and heart rate and a decrease in Tc. Then, when BMI was microinjected bilaterally into the PPy, no direct effect on Ts was seen; and thermogenic and tachycardic responses were slight. However, pretreatment of the PPy with BMI, but not vehicle saline, greatly attenuated the hypothermic responses evoked by hypoxic (10%O2-90%N2, 5min) ventilation or bilateral microinjections of glutamate (5nmol, each side) into the LPO. The results suggest that hypoxia-induced hypothermia was mediated, at least in part, by the activation of GABAA receptors in the PPy. PMID:24607346

  7. Characterization of muscarinic receptors in rat kidney.

    PubMed

    Blankesteijn, W M; Siero, H L; Rodrigues de Miranda, J F; van Megen, Y J; Russel, F G

    1993-01-01

    Muscarinic receptors in mammalian kidney seem to be involved in diuresis. In this study we give a detailed characterization of receptors in rat kidney. Specific binding of [3H](-)-quinuclidinylbenzilate ([3H]QNB) to membranes of rat kidney cortex was saturable and of high affinity. A dissociation constant of 0.063 +/- 0.003 nM and a receptor density of 1.46 +/- 0.07 pmol/g wet weight were obtained. The dissociation kinetics could be best described by assuming a mono-exponential function (k-1 = (0.52 +/- 0.1) x 10(-4) s-1). The binding of [3H]QNB reached a maximum in 60 min at 0.6 nM at 37 degrees C. Competition experiments with the enantiomers of benzetimide confirmed the muscarinic nature of the [3H]QNB binding sites. The inhibition constants of pirenzepine (0.23 +/- 0.02 microM), (+-)-hexahydrosiladifenidol (0.040 +/- 0.002 microM), AF-DX 116 (1.45 +/- 0.07 microM), methoctramine (1.67 +/- 0.02 microM) and gallamine (78 +/- 3 microM) classified this receptor as an M3 receptor. Inhibition of [3H]QNB binding by the agonists methylfurtrethonium, arecoline, isoarecoline methiodide, arecaidine propargyl ester and McN-A-343 displayed monophasic inhibition curves. With (+/-)-cis-2-methyl-4-dimethylaminomethyl-1,3- dioxolane methiodide in two out of four experiments a small (11%) population of high affinity agonist sites could be detected. The potassium sparing diuretic amiloride inhibited [3H]QNB binding (36 +/- 3 microM). Although in a way related to the amiloride binding site, the muscarinic receptors in rat kidney are unlikely to be the primary target of diuretic action of this drug. PMID:8420789

  8. Arachidonic acid mediates muscarinic inhibition and enhancement of N-type Ca2+ current in sympathetic neurons

    PubMed Central

    Liu, Liwang; Rittenhouse, Ann R.

    2003-01-01

    N-type Ca2+ channels participate in acute activity-dependent processes such as regulation of Ca2+-activated K+ channels and in more prolonged events such as gene transcription and long-term depression. A slow postsynaptic M1 muscarinic receptor-mediated modulation of N-type current in superior cervical ganglion neurons may be important in regulating these processes. This slow pathway inhibits N-type current by using a diffusible second messenger that has remained unidentified for more than a decade. Using whole-cell patch–clamp techniques, which isolate the slow pathway, we found that the muscarinic agonist oxotremorine methiodide not only inhibits currents at positive potentials but enhances N-type current at negative potentials. Enhancement was also observed in cell-attached patches. These findings provide evidence for N-type Ca2+-current enhancement by a classical neurotransmitter. Moreover, enhancement and inhibition of current by oxotremorine methiodide mimics modulation observed with direct application of a low concentration of arachidonic acid (AA). Although no transmitter has been reported to use AA as a second messenger to modulate any Ca2+ current in either neuronal or nonneuronal cells, we nevertheless tested whether a fatty acid signaling cascade was involved. Blocking phospholipase C, phospholipase A2, or AA but not AA metabolism minimized muscarinic modulation of N-type current, supporting the participation of these molecules in the slow pathway. A role for the G protein Gq was also confirmed by blocking muscarinic modulation of Ca2+ currents with anti-Gqα antibody. Our finding that AA participates in the slow pathway strongly suggests that it may be the previously unknown diffusible second messenger. PMID:12496347

  9. Binding and functional properties of antimuscarinics of the hexocyclium/sila-hexocyclium and hexahydro-diphenidol/hexahydro-sila-diphenidol type to muscarinic receptor subtypes.

    PubMed

    Waelbroeck, M; Tastenoy, M; Camus, J; Christophe, J; Strohmann, C; Linoh, H; Zilch, H; Tacke, R; Mutschler, E; Lambrecht, G

    1989-09-01

    1. In an attempt to assess the structural requirements for the muscarinic receptor selectivity of hexahydro-diphenidol (hexahydro-difenidol) and hexahydro-sila-diphenidol (hexahydro-sila-difenidol), a series of structurally related C/Si pairs were investigated, along with atropine, pirenzepine and methoctramine, for their binding affinities in NB-OK 1 cells as well as in rat heart and pancreas. 2. The action of these antagonists at muscarinic receptors mediating negative inotropic responses in guinea-pig atria and ileal contractions has also been assessed. 3. Antagonist binding data indicated that NB-OK 1 cells (M1 type) as well as rat heart (cardiac type) and pancreas (glandular/smooth muscle type) possess different muscarinic receptor subtypes. 4. A highly significant correlation was found between the binding affinities of the antagonists to muscarinic receptors in rat heart and pancreas, respectively, and the affinities to muscarinic receptors in guinea-pig atria and ileum. This implies that the muscarinic binding sites in rat heart and the receptors in guinea-pig atria are essentially similar, but different from those in pancreas and ileum. 5. The antimuscarinic potency of hexahydro-diphenidol and hexahydro-sila-diphenidol at the three subtypes was influenced differently by structural modifications (e.g. quaternization). Different selectivity profiles for the antagonists were obtained, which makes these compounds useful tools to investigate further muscarinic receptor heterogeneity. Indeed, the tertiary analogues hexahydro-diphenidol (HHD) and hexahydro-sila-diphenidol (HHSiD) had an M1 = glandular/smooth muscle greater than cardiac selectivity profile, whereas the quaternary analogues HHD methiodide and HHSiD methiodide were M1 preferring (M1 greater than glandular/smooth muscle, cardiac). PMID:2804545

  10. Binding and functional properties of antimuscarinics of the hexocyclium/sila-hexocyclium and hexahydro-diphenidol/hexahydro-sila-diphenidol type to muscarinic receptor subtypes.

    PubMed Central

    Waelbroeck, M.; Tastenoy, M.; Camus, J.; Christophe, J.; Strohmann, C.; Linoh, H.; Zilch, H.; Tacke, R.; Mutschler, E.; Lambrecht, G.

    1989-01-01

    1. In an attempt to assess the structural requirements for the muscarinic receptor selectivity of hexahydro-diphenidol (hexahydro-difenidol) and hexahydro-sila-diphenidol (hexahydro-sila-difenidol), a series of structurally related C/Si pairs were investigated, along with atropine, pirenzepine and methoctramine, for their binding affinities in NB-OK 1 cells as well as in rat heart and pancreas. 2. The action of these antagonists at muscarinic receptors mediating negative inotropic responses in guinea-pig atria and ileal contractions has also been assessed. 3. Antagonist binding data indicated that NB-OK 1 cells (M1 type) as well as rat heart (cardiac type) and pancreas (glandular/smooth muscle type) possess different muscarinic receptor subtypes. 4. A highly significant correlation was found between the binding affinities of the antagonists to muscarinic receptors in rat heart and pancreas, respectively, and the affinities to muscarinic receptors in guinea-pig atria and ileum. This implies that the muscarinic binding sites in rat heart and the receptors in guinea-pig atria are essentially similar, but different from those in pancreas and ileum. 5. The antimuscarinic potency of hexahydro-diphenidol and hexahydro-sila-diphenidol at the three subtypes was influenced differently by structural modifications (e.g. quaternization). Different selectivity profiles for the antagonists were obtained, which makes these compounds useful tools to investigate further muscarinic receptor heterogeneity. Indeed, the tertiary analogues hexahydro-diphenidol (HHD) and hexahydro-sila-diphenidol (HHSiD) had an M1 = glandular/smooth muscle greater than cardiac selectivity profile, whereas the quaternary analogues HHD methiodide and HHSiD methiodide were M1 preferring (M1 greater than glandular/smooth muscle, cardiac). PMID:2804545

  11. Modulation of the release of norepinephrine by gamma-aminobutyric acid and morphine in the frontal cerebral cortex of the rat

    SciTech Connect

    Peoples, R.W.

    1989-01-01

    Agents that enhance gamma-aminobutyric acid, or GABA, neurotransmission modulate certain effects of opioids, such as analgesia. Opioid analgesia is mediated in part by norepinephrine in the forebrain. In this study, the interactions between morphine and GABAergic agents on release of ({sup 3}H) norepinephrine from rat frontal cerebral cortical slices were examined. GABA, 5 {times} 10{sup {minus}5}-10{sup {minus}3} M, enhanced potassium stimulated ({sup 3}H) norepinephrine release and reversed the inhibitory effect of morphine in a noncompetitive manner. GABA did not enhance release of ({sup 3}H) norepinephrine stimulated by the calcium ionophore A23187. The effect of GABA was reduced by the GABA{sub A} receptor antagonists bicuculline methiodide or picrotoxin, and by the selective inhibitor of GABA uptake SKF 89976A, but was blocked completely only when bicuculline methiodide and SKF 89976A were used in combination. The GABA{sub A} agonist muscimol, 10{sup {minus}4} M, mimicked the effect of GABA, but the GABA{sub B} agonist ({plus minus})baclofen, 10{sup {minus}4} M, did not affect the release of ({sup 3}H) norepinephrine in the absence or the presence of morphine. Thus GABA appears to produce this effect by stimulating GABA uptake and GABA{sub A}, but not GABA{sub B}, receptors. In contrast to the results that would be predicted for an event involving GABA{sub A} receptors, however, the effect of GABA did not desensitize, and benzodiazepine agonists did not enhance the effect of GABA at any concentration tested between 10{sup {minus}8} and 10{sup {minus}4} M. Thus these receptors may constitute a subclass of GABA{sub A} receptors. These results support a role of GABA uptake and GABA{sub A} receptors in enhancing the release of norepinephrine and modulating its inhibition by opioids in the frontal cortex of the rat.

  12. In vivo imaging of epileptic foci in rats using a miniature probe integrating diffuse optical tomography and electroencephalographic source localization

    PubMed Central

    Yang, Hao; Zhang, Tao; Zhou, Junli; Carney, Paul R.; Jiang, Huabei

    2014-01-01

    SUMMARY Objective The goal of this work is to establish a new dual-modal brain mapping technique based on diffuse optical tomography (DOT) and electroencephalographic source localization (ESL) that can chronically/intracranially record optical/EEG data to precisely map seizures and localize the seizure onset zone and associated epileptic brain network. Methods The dual-modal imaging system was employed to image seizures in an experimental acute bicuculline methiodide rat model of focal epilepsy. Depth information derived from DOT was used as constraint in ESL to enhance the image reconstruction. Groups of animals were compared based on localization of seizure foci, either at different positions or at different depths. Results This novel imaging technique successfully localized the seizure onset zone in rat induced by bicuculline methiodide injected at a depth of 1mm, 2mm and 3mm, respectively. The results demonstrated that the incorporation of the depth information from DOT into the ESL image reconstruction resulted in more accurate and reliable ESL images. Although the ESL images showed a horizontal shift of the source localization, the DOT identified the seizure focus accurately. In one case, when the BMI was injected at a site outside the field of view (FOV) of the DOT/ESL interface, ESL gives false positive detection of the focus while DOT shows negative detection. Significance This study represents the first to identify seizure onset zone using implantable DOT. In addition, the combination of DOT/ESL has never been documented in neuroscience and epilepsy imaging. This technology will enable us to precisely measure the neural activity and hemodynamic response at exactly the same tissue site and at both cortical and sub cortical levels. PMID:25524046

  13. GABAA receptor-mediated positive inotropism in guinea-pig isolated left atria: evidence for the involvement of capsaicin-sensitive nerves.

    PubMed Central

    Maggi, C. A.; Giuliani, S.; Manzini, S.; Meli, A.

    1989-01-01

    1. Isolated left atria from reserpine-pretreated guinea-pigs, electrically driven (3 Hz) in the presence of atropine (1 microM), phentolamine (0.3 microM) and propranolol (1 microM), responded to a train of stimuli (10 Hz for 2.5s) with a delayed neurogenic positive inotropic response which was insensitive to hexamethonium (10 microM) but abolished by either tetrodotoxin (1 microM), omega-conotoxin (0.1 microM), in vitro capsaicin desensitization or desensitization to calcitonin gene-related peptide (CGRP). 2. In these experimental conditions, gamma-aminobutyric acid (GABA) produced a concentration-related (10 microM-1 mM) positive inotropic response similar to that produced by electrical field stimulation. The effect of GABA was competitively antagonized by bicuculline methiodide (10 microM), a GABAA receptor antagonist. 3. The selective GABAA receptor agonists, muscimol and homotaurine mimicked the positive inotropic effect of GABA while baclofen, the selective GABAB receptor agonist, did not. 4. The action of GABA (1 mM) was abolished by either tetrodotoxin (1 microM), omega-conotoxin (0.1 microM), in vitro capsaicin desensitization or desensitization to CGRP, while it was unaffected by hexamethonium. In contrast, the inotropic response to CGRP was unaffected by tetrodotoxin, omega-conotoxin, bicuculline methiodide, hexamethonium or in vitro capsaicin desensitization, but was abolished by CGRP desensitization. 5. In the spontaneously beating guinea-pig right atrium, GABA (1 microM) produced a small and transient positive chronotropic effect that was no longer observed after in vitro desensitization with capsaicin (1 microM). 6. In the guinea-pig isolated perfused heart from reserpine-pretreated animals (with atropine, phentolamine and propranolol in the perfusion medium), GABA (1 microM) produced a transient tachycardia and a small increase in coronary flow.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2541852

  14. Nucleophilic Polymers and Gels in Hydrolytic Degradation of Chemical Warfare Agents.

    PubMed

    Bromberg, Lev; Creasy, William R; McGarvey, David J; Wilusz, Eugene; Hatton, T Alan

    2015-10-01

    Water- and solvent-soluble polymeric materials based on polyalkylamines modified with nucleophilic groups are introduced as catalysts of chemical warfare agent (CWA) hydrolysis. A comparative study conducted at constant pH and based on the criteria of the synthetic route simplicity, aqueous solubility, and rate of hydrolysis of CWA mimic, diisopropylfluorophosphate (DFP), indicated that 4-aminopyridine-substituted polyallylamine (PAAm-APy) and polyvinylamine substituted with 4-aminopyridine (PVAm-APy) were advantageous over 4-pyridinealdoxime-modified PVAm and PAAm, poly(butadiene-co-pyrrolidinopyridine), and PAAm modified with bipyridine and its complex with Cu(II). The synthesis of PVAm-APy and PAAm-APy involved generation of a betaine derivative of acrylamide and its covalent attachment onto the polyalkylamine chain followed by basic hydrolysis. Hydrogel particles of PAAm-APy and PVAm-APy cross-linked by epichlorohydrin exhibited pH-dependent swelling and ionization patterns that affected the rate constants of DFP nucleophilic hydrolysis. Deprotonation of the aminopyridine and amine groups increased the rates of the nucleophilic hydrolysis. The second-order rate of nucleophilic hydrolysis was 5.5- to 10-fold higher with the nucleophile-modified gels compared to those obtained by cross-linking of unmodified PAAm, throughout the pH range. Testing of VX and soman (GD) was conducted in 2.5-3.7 wt % PVAm-APy suspensions or gels swollen in water or DMSO/water mixtures. The half-lives of GD in aqueous PVAm-APy were 12 and 770 min at pH 8.5 and 5, respectively. Addition of VX into 3.5-3.7 wt % suspensions of PVAm-APy in DMSO-d6 and D2O at initial VX concentration of 0.2 vol % resulted in 100% VX degradation in less than 20 min. The unmodified PVAm and PAAm were 2 orders of magnitude less active than PVAm-APy and PAAm-APy, with VX half-lives in the range of 24 h. Furthermore, the PVAm-APy and PAAm-APy gels facilitated the dehydrochlorination reaction of sulfur mustard

  15. Exploring the positive allosteric modulation of human α7 nicotinic receptors from a single-channel perspective.

    PubMed

    Andersen, Natalia D; Nielsen, Beatriz E; Corradi, Jeremías; Tolosa, María F; Feuerbach, Dominik; Arias, Hugo R; Bouzat, Cecilia

    2016-08-01

    Enhancement of α7 nicotinic receptor (nAChR) function by positive allosteric modulators (PAMs) is a promising therapeutic strategy to improve cognitive deficits. PAMs have been classified only on the basis of their macroscopic effects as type I, which only enhance agonist-induced currents, and type II, which also decrease desensitization and reactivate desensitized nAChRs. To decipher the molecular basis underlying these distinct activities, we explored the effects on single-α7 channel currents of representative members of each type and of less characterized compounds. Our results reveal that all PAMs enhance open-channel lifetime and produce episodes of successive openings, thus indicating that both types affect α7 kinetics. Different PAM types show different sensitivity to temperature, suggesting different mechanisms of potentiation. By using a mutant α7 receptor that is insensitive to the prototype type II PAM (PNU-120596), we show that some though not all type I PAMs share the structural determinants of potentiation. Overall, our study provides novel information on α7 potentiation, which is key to the ongoing development of therapeutic compounds. PMID:26926428

  16. Peripheral antinociceptive effects of the cyclic endomorphin-1 analog c[YpwFG] in a mouse visceral pain model.

    PubMed

    Bedini, Andrea; Baiula, Monica; Gentilucci, Luca; Tolomelli, Alessandra; De Marco, Rossella; Spampinato, Santi

    2010-11-01

    We previously described a novel cyclic endomorphin-1 analog c[Tyr-D-Pro-D-Trp-Phe-Gly] (c[YpwFG]), acting as a mu-opioid receptor (MOR) agonist. This study reports that c[YpwFG] is more lipophilic and resistant to enzymatic hydrolysis than endomorphin-1 and produces preemptive antinociception in a mouse visceral pain model when injected intraperitoneally (i.p.) or subcutaneously (s.c.) before 0.6% acetic acid, employed to evoke abdominal writhing (i.p. ED(50)=1.24 mg/kg; s.c. ED(50)=2.13 mg/kg). This effect is reversed by the selective MOR antagonist β-funaltrexamine and by a high dose of the mu(1)-opioid receptor-selective antagonist naloxonazine. Conversely, the kappa-opioid receptor antagonist nor-binaltorphimine and the delta-opioid receptor antagonist naltrindole are ineffective. c[YpwFG] produces antinociception when injected i.p. after acetic acid (ED(50)=4.80 mg/kg), and only at a dose of 20mg/kg did it elicit a moderate antinociceptive response in the mouse, evaluated by the tail flick assay. Administration of a lower dose of c[YpwFG] (10mg/kg i.p.) apparently produces a considerable part of antinociception on acetic acid-induced writhes through peripheral opioid receptors as this action is fully prevented by i.p. naloxone methiodide, which does not readily cross the blood-brain barrier; whereas this opioid antagonist injected intracerebroventricularly (i.c.v.) is not effective. Antinociception produced by a higher dose of c[YpwFG] (20mg/kg i.p.) is partially reversed by naloxone methiodide i.c.v. administered. Thus, only at the dose of 20mg/kg c[YpwFG] can produce antinociception through both peripheral and central opioid receptors. In conclusion, c[YpwFG] displays sufficient metabolic stability to be effective after peripheral administration and demonstrates the therapeutic potential of endomorphin derivatives as novel analgesic agents to control visceral pain. PMID:20713109

  17. Rapid EEG desynchronization and EMG activation induced by intravenous cocaine in freely moving rats: a peripheral, nondopamine neural triggering.

    PubMed

    Kiyatkin, Eugene A; Smirnov, Michael S

    2010-02-01

    Many important physiological, behavioral, and psychoemotional effects of intravenous (IV) cocaine (COC) are too fast and transient compared with pharmacokinetic predictions, suggesting a possible involvement of peripheral neural mechanisms in their triggering. In the present study, we examined changes in cortical electroencephalogram (EEG) and neck electromyogram (EMG) induced in freely moving rats by IV COC administration at low, reinforcing doses (0.25-1.0 mg/kg) and compared them with those induced by an auditory stimulus and IV COC methiodide, which cannot cross the blood-brain barrier. We found that COC induces rapid, strong, and prolonged EEG desynchronization, associated with decrease in alpha and increase in beta and gamma activities, and EMG activation and that both begin within 2-6 s following the start of a 10-s injection; immediate components of this effect were dose independent. The rapid COC-induced changes in EEG and EMG resembled those induced by an auditory stimulus; the latter effects had shorter onset latencies and durations and were fully blocked during urethane anesthesia. Although urethane anesthesia completely blocked COC-induced EMG activation and rapid components of EEG response, COC still induced EEG desynchronization that was much weaker, greatly delayed (approximately 60 s), and associated with tonic decreases in delta and increases in alpha, beta, and gamma activities. Surprisingly, IV saline delivered during slow-wave sleep (but not quite wakefulness) also induced a transient EEG desynchronization but without changes in EMG activity; these effects were also fully blocked during anesthesia. Peripherally acting COC methiodide fully mimicked rapid EEG and EMG effects of regular COC, but the effects at an equimolar dose were less prolonged than those with regular COC. These data suggest that in awake animals IV COC, like somato-sensory stimuli, induces cortical activation and a subsequent motor response via its action on peripheral neural

  18. RELATIVE ACTIONS OF QUATERNARY METHYL DERIVATIVES OF TYRAMINE, DOPAMINE AND NORADRENALINE.

    PubMed

    CUTHBERT, M F

    1964-08-01

    Tyramine methiodide and dopamine methobromide have greater pressor effect (three- to five-times) in the spinal cat than the parent amines. Noradrenaline methochloride has little pressor effect. Dopamine methobromide is about four times as potent as nicotine; tyramine methiodide is about equiactive to nicotine; and noradrenaline methochloride has only one-tenth the potency of nicotine. Their pressor effects are usually abolished by hexamethonium but in some experiments the effect of noradrenaline methochloride persisted and was then abolished by tolazoline. Injected intravenously into the cat anaesthetized with chloralose, each of the three quaternary derivatives contracts the nictitating membrane; dopamine methobromide is again the most active, having more than six times the potency of nicotine. When the contractions of the nictitating membrane are induced by continuous stimulation of the preganglionic fibres of the cervical sympathetic nerve, intravenous injection of the quaternary derivatives of tyramine and dopamine has a biphasic effect; there is a block on which a contraction of the membrane appears to be superimposed. Noradrenaline methochloride produces only a further contraction of the membrane. On the isolated rectus abdominis muscle preparation of the frog, dopamine methobromide is the most active in contracting the muscle, being about twelve times as active as nicotine; noradrenaline methochloride is weakest, having only one-hundredth the activity of nicotine. These effects are antagonized by hexamethonium. On the isolated phrenic nerve-diaphragm preparation of the rat, the quaternary derivatives of tyramine and dopamine each have neuromuscular blocking properties, 0.7- and 3-times respectively that of nicotine. Noradrenaline methochloride has no effect. In the sciatic nerve-tibialis preparation of the cat, the quaternary derivatives of tyramine and dopamine are approximately equipotent in producing neuromuscular paralysis, having about three times the

  19. Effect of cocaine and methylecgonidine on intracellular Ca2+ and myocardial contraction in cardiac myocytes.

    PubMed

    Huang, L; Woolf, J H; Ishiguro, Y; Morgan, J P

    1997-08-01

    We evaluated the cardiac effects of the principle pyrolysis product of crack cocaine smoking, methylecgonidine (MEG), in comparison with cocaine. Peak cell shortening and intracellular Ca2+, as detected by the Ca2+ indicator indo 1, were recorded in enzymatically isolated ferret myocytes. Both cocaine and MEG decreased peak cell shortening and peak intracellular Ca2+ concentration ([Ca2+]i) in a dose-dependent manner (10(-8)-10(-4) M). MEG shifted the peak [Ca2+]i-to-peak shortening relationship downward and was more potent than cocaine. Atropine (10(-6) M) upwardly shifted the dose-response curves of MEG, cocaine, and carbachol but not of procaine. The negative inotropic effects of MEG were inhibited by methoctramine, a selective M2 receptor blocker but not by M1 (pirenzepine) or M3 (4-diphenylacetoxy-N-methylpiperidine methiodide) blocking agents. In contrast to cocaine, the effects of large doses of MEG were irreversible over the time course of our experiments, raising the possibility of structural damage. We conclude that MEG acts primarily on M2 cholinergic receptors in the heart to produce acute cardiac intoxication and, in contrast to cocaine, may decrease the myofilament Ca2+ responseness and cause structural damage to myocytes by a direct toxic effect. PMID:9277508

  20. Across-frequency nonlinear inhibition by GABA in processing of interaural time difference.

    PubMed

    Mori, K

    1997-09-01

    The barn owl uses the interaural time difference (ITD) to determine the azimuth of a sound source. Narrowband ITD-sensitive neurons cannot distinguish a given ITD from those that produce the same interaural phase difference (phase ambiguity). Neurons in the external nucleus of the inferior colliculus (ICx) resolve the ambiguity by gathering ITD information across many frequencies, thereby suppressing false responses (side peaks, SP) relative to the true ITD (the main peak, MP) in a response versus ITD curve. This process was quantitatively studied by comparing the ITD curve for a pair of tones presented simultaneously (two-tone curve) to the simple sum (predicted curve) of the individual ITD curves for the same tones presented separately. Sixteen of the 39 neurons tested did not show a significant difference in MP and SP responses between these curves (category I); 14 neurons showed significant SP suppression (category II). During iontophoretic application of bicuculline methiodide, a GABA(A) antagonist, most (n = 7/8) category II neurons lost nonlinear SP suppression and became linear, whereas category I neurons retained linear summation (n = 3/3). Thus, the nonlinear cross-frequency interaction of ITD responses in ICx neurons was mediated mostly by GABAergic inhibition, which enhanced SP suppression, and helped resolve phase ambiguity. PMID:9307308

  1. [Interactions of peripheral mu-opioid receptors and K(ATP)-channels in regulation of cardiac electrical stability in ischemia, reperfusion, and postinfarction cardiosclerosis].

    PubMed

    Maslov, L N; Krylatov, A V; Naryzhaia, N V; Solenkova, N V; Lishmanov, A Iu; Bogomaz, S A; Gross, G J; Stefano, J B; Loktiushina, B A

    2002-07-01

    It has been shown that mu-opioid receptor stimulation by intravenous administration of the selective mu receptor agonist DALDA in a dose of 0.1 mg/kg prevented ischemic and reperfusion arrhythmias in rats subjected to coronary artery occlusion (10 min) and reperfusion (10 min), and also increased the ventricular fibrillation threshold in rats with postinfarction cardiac fibrosis. These effects were abolished by pre-treatment with the selective mu receptor antagonist CTAP in a dose of 0.5 mg/kg or by prior injection of the opioid receptor antagonist naloxone methiodide (2 mg/kg) which does not penetrate the blood-braib barrier. Both antagonists by themselves had no effect on the incidence of occlusion or reperfusion-induced arrhythmias or on the ventricular fibrillation threshold. Pre-treatment with ATP-sensitive K+ channel (KATP channel) blocker glibenclamide in a dose of 0.3 mg/kg completely abolished the antiarrhythmic effect of DALDA. We believe that DALDA prevents occurrence of electrical instability during ischemia and reperfusion and increases the ventricular fibrillation threshold in rats with postinfarction cardiac fibrosis via stimulation of peripheral mu-opioid receptor which appear to be coupled to the KATP channel. PMID:12238351

  2. New series of monoquaternary pyridinium oximes: synthesis and reactivation potency for paraoxon-inhibited electric eel and recombinant human acetylcholinesterase

    PubMed Central

    Bharate, Sandip B.; Guo, Lilu; Reeves, Tony E.; Cerasoli, Douglas M.; Thompson, Charles M.

    2009-01-01

    The preparation of a series of monoquaternary pyridinium oximes bearing either a heterocyclic side chain or a functionalized aliphatic side chain and the corresponding in vitro evaluation for reactivation of paraoxon-inhibited electric eel acetylcholinesterase (EeAChE) and recombinant human acetylcholinesterase (rHuAChE) are reported. Several newly synthesized compounds efficiently reactivated inhibited EeAChE, but were poor reactivators of inhibited rHuAChE. Compounds bearing a thiophene ring in the side chain (20, 23, 26 and 29) showed better reactivation (24–37% for EeAChE and 5–9% for rHuAChE) compared to compounds with furan and isoxazole heterocycles (0–8% for EeAChE and 2–3% for rHuAChE) at 10−5 M. The N-pyridyl-CH2COOH analog 8 reactivated EeAChE (36%) and rHuAChE (15%) at 10−4 M with a kr value better than 2-pyridine aldoxime methiodide (2-PAM) for rHuAChE. PMID:19640713

  3. Biphalin preferentially recruits peripheral opioid receptors to facilitate analgesia in a mouse model of cancer pain - A comparison with morphine.

    PubMed

    Lesniak, Anna; Bochynska-Czyz, Marta; Sacharczuk, Mariusz; Benhye, Sandor; Misicka, Aleksandra; Bujalska-Zadrozny, Magdalena; Lipkowski, Andrzej W

    2016-06-30

    The search for new drugs for cancer pain management has been a long-standing goal in basic and clinical research. Classical opioid drugs exert their primary antinociceptive effect upon activating opioid receptors located in the central nervous system. A substantial body of evidence points to the relevance of peripheral opioid receptors as potential targets for cancer pain treatment. Peptides showing limited blood-brain-barrier permeability promote peripheral analgesia in many pain models. In the present study we examined the peripheral and central analgesic effect of intravenously administered biphalin - a dimeric opioid peptide in a mouse skin cancer pain model, developed by an intraplantar inoculation of B16F0 melanoma cells. The effect of biphalin was compared with morphine - a golden standard in cancer pain management. Biphalin produced profound, dose-dependent and naloxone sensitive spinal analgesia. Additionally, the effect in the tumor-bearing paw was largely mediated by peripheral opioid receptors, as it was readily attenuated by the blood-brain-barrier-restricted opioid receptor antagonist - naloxone methiodide. On the contrary, morphine facilitated its analgesic effect primarily by activating spinal opioid receptors. Both drugs induced tolerance in B16F0 - implanted paws after chronic treatment, however biphalin as opposed to morphine, showed little decrease in its activity at the spinal level. Our results indicate that biphalin may be considered a future alternative drug in cancer pain treatment due to an enhanced local analgesic activity as well as lower tolerance liability compared with morphine. PMID:27094782

  4. Powerful anticonvulsant action of IL-1 receptor antagonist on intracerebral injection and astrocytic overexpression in mice

    PubMed Central

    Vezzani, A.; Moneta, D.; Conti, M.; Richichi, C.; Ravizza, T.; De Luigi, A.; De Simoni, M. G.; Sperk, G.; Andell-Jonsson, S.; Lundkvist, J.; Iverfeldt, K.; Bartfai, T.

    2000-01-01

    IL-1β and its endogenous receptor antagonist (IL-1Ra) are rapidly induced by seizures in the rodent hippocampus. Exogenously applied IL-1β prolongs seizures in an IL-1R type I-mediated manner. This effect depends on N-methyl-d-aspartate receptor activation. We report here that intrahippocampal application of recombinant IL-1Ra or its selective endogenous overexpression in astrocytes under the control of glial acidic fibrillary protein promoter potently inhibits motor and electroencephalographic seizures induced by bicuculline methiodide in mice. Accordingly, transgenic mice show a reduced seizure-related c-fos mRNA expression in various forebrain areas compared with their wild-type littermates. Recombinant IL-1Ra was ineffective in mice deficient in IL-1R type I, having per se a delayed onset to generalized convulsions. These results demonstrate that IL-1Ra mediates potent anticonvulsant effects acting on IL-1R type I and suggest that the balance between brain IL-1β and IL-1Ra represents a crucial mechanism to control seizure generalization. PMID:11016948

  5. Bone Marrow Stromal Cells Produce Long-Term Pain Relief in Rat Models of Persistent Pain

    PubMed Central

    Guo, Wei; Wang, Hu; Zou, Shiping; Gu, Ming; Watanabe, Mineo; Wei, Feng; Dubner, Ronald; Huang, George T.-J.; Ren, Ke

    2012-01-01

    Chronic pain conditions are difficult to treat and are major health problems. Bone marrow stromal cells (BMSCs) have generated considerable interest as a candidate for cell-based therapy. BMSCs are readily accessible and are easy to isolate and expand ex vivo. Clinical studies show that direct injection of BMSCs does not produce unwanted side effects and is well tolerated and safe. Here, we show that a single systemic (intravenous) or local injection (into the lesion site) of rat primary BMSCs reversed pain hypersensitivity in rats after injury and that the effect lasted until the conclusion of the study at 22 weeks. The pain hypersensitivity was rekindled by naloxone hydrochloride, an opioid receptor antagonist that acts peripherally and centrally, when tested at 1–5 weeks after BMSC infusion. In contrast, naloxone methiodide, a peripherally acting opioid receptor antagonist, only rekindled hyperalgesia in the first 3 weeks of BMSC treatment. Focal downregulation of brainstem mu opioid receptors by RNA interference (RNAi) reversed the effect of BMSCs, when RNAi was introduced at 5- but not 1-week after BMSC transplantation. Thus, BMSCs produced long-term relief of pain and this effect involved activation of peripheral and central opioid receptors in distinct time domains. The findings prompt studies to elucidate the cellular mechanisms of the BMSC-induced pain relieving effect and translate these observations into clinical settings. PMID:21630378

  6. Recovery of brain and plasma cholinesterase activities in ducklings exposed to organophosphorus pesticides

    USGS Publications Warehouse

    Fleming, W.J.

    1981-01-01

    Brain and plasma cholinesterase (ChE) activities were determined for mallard ducklings (Anas platyrhynchos) exposed to dicrotophos and fenthion. Recovery rates of brain ChE did not differ between ducklings administered a single oral dose vs. a 2-week dietary dose of these organophosphates. Exposure to the organophosphates, followed by recovery of brain ChE, did not significantly affect the degree of brain ChE inhibition or the recovery of ChE activity at a subsequent exposure. Recovery of brain ChE activity followed the general model Y = a + b(logX) with rapid recovery to about 50% of normal, followed by a slower rate of recovery until normal ChE activity levels were attained. Fenthion and dicrotophos-inhibited brain ChE were only slightly reactivated in vitro by pyridine-2-aldoxime methiodide, which suggested that spontaneous reactivation was not a primary method of recovery of ChE activity. Recovery of brain ChE activity can be modeled for interpretation of sublethal inhibition of brain ChE activities in wild birds following environmental applications of organophosphates. Plasma ChE activity is inferior to brain ChE activity for environmental monitoring, because of its rapid recovery and large degree of variation among individuals.

  7. Synthesis and opioid receptor affinity of a series of 2, 4-diaryl-substituted 3,7-diazabicylononanones.

    PubMed

    Siener, T; Cambareri, A; Kuhl, U; Englberger, W; Haurand, M; Kögel, B; Holzgrabe, U

    2000-10-01

    3,7-Diazabicyclo[3.3.1]nonan-9-ones having aryl rings in positions 2 and 4 with systematically varied substituents were synthesized using a double Mannich procedure. Radioligand binding assays were performed to measure the affinity of the compounds to the mu-, delta-, and kappa-opioid receptors. The affinity of all 2, 4-diphenyl-substituted 3,7-diazabicyclo[3.3.1]nonan-9-ones to the mu- and delta-receptors was found to be low. In contrast, with exception of the nitro- and cyanophenyl-substituted compounds, most of the diazabicycles showed considerable affinity for the kappa-receptor. In particular, the m-fluoro-, p-methoxy-, and m-hydroxy-substituted compounds have an affinity in the submicromolar range. Due to solubility problems in aqueous media, salts of HZ2 were synthesized. The methiodide shows high kappa-affinity and may, thus, be a promising candidate for development of a peripheral kappa-agonist, e.g. for use in the case of rheumatoid arthritis. PMID:11020289

  8. Physiology and pharmacology of acetylcholinergic responses of interneurons in the antennal lobes of the moth Manduca sexta.

    PubMed

    Waldrop, B; Hildebrand, J G

    1989-01-01

    1. Neurons in the antennal lobe (AL) of the moth Manduca sexta respond to the application, via pressure injection into the neuropil, of acetylcholine (ACh). When synaptic transmission is not blocked, both excitatory (Fig. 2) and inhibitory (Fig. 3) responses are seen. 2. Responses to ACh appear to be receptor-mediated, as they are associated with an increase in input conductance (Figs. 2B and 3B) and are dose-dependent (Fig. 2 C). 3. All neurons responsive to ACh are also excited by nicotine. Responses to nicotine are stronger and more prolonged than responses to ACh (Fig. 4C). No responses are observed to the muscarinic agonist, oxotremorine (Fig. 4 B). 4. Curare blocks responses of AL neurons to applied ACh, while atropine and dexetimide are only weakly effective at reducing ACh responses (Figs. 5 and 6). 5. Curare is also more effective than atropine or dexetimide at reducing synaptically-mediated responses of AL neurons (Fig. 7). 6. In one AL neuron, bicuculline methiodide (BMI) blocked the IPSP produced by electrical stimulation of the antennal nerve, but it did not reduce the inhibitory response to application of ACh (Fig. 8). PMID:2926690

  9. Intraplantar injection of bergamot essential oil induces peripheral antinociception mediated by opioid mechanism.

    PubMed

    Sakurada, Tsukasa; Mizoguchi, Hirokazu; Kuwahata, Hikari; Katsuyama, Soh; Komatsu, Takaaki; Morrone, Luigi Antonio; Corasaniti, Maria Tiziana; Bagetta, Giacinto; Sakurada, Shinobu

    2011-01-01

    This study investigated the effect of bergamot essential oil (BEO) containing linalool and linalyl acetate as major volatile components in the capsaicin test. The intraplantar injection of capsaicin (1.6 μg) produced a short-lived licking/biting response toward the injected paw. The nociceptive behavioral response evoked by capsaicin was inhibited dose-dependently by intraplantar injection of BEO. Both linalool and linalyl acetate, injected into the hindpaw, showed a significant reduction of nociceptive response, which was much more potent than BEO. Intraperitoneal (i.p.) and intraplantar pretreatment with naloxone hydrochloride, an opioid receptor antagonist, significantly reversed BEO- and linalool-induced antinociception. Pretreatment with naloxone methiodide, a peripherally acting μ-opioid receptor preferring antagonist, resulted in a significant antagonizing effect on antinociception induced by BEO and linalool. Antinociception induced by i.p. or intrathecal morphine was enhanced by the combined injection of BEO or linalool. The enhanced effect of combination of BEO or linalool with morphine was antagonized by pretreatment with naloxone hydrochloride. Our results provide evidence for the involvement of peripheral opioids, in the antinociception induced by BEO and linalool. Combined administration of BEO or linalool acting at the peripheral site, and morphine may be a promising approach in the treatment of clinical pain. PMID:20932858

  10. Effect of plantar subcutaneous administration of bergamot essential oil and linalool on formalin-induced nociceptive behavior in mice.

    PubMed

    Katsuyama, Soh; Otowa, Akira; Kamio, Satomi; Sato, Kazuma; Yagi, Tomomi; Kishikawa, Yukinaga; Komatsu, Takaaki; Bagetta, Giacinto; Sakurada, Tsukasa; Nakamura, Hitoshi

    2015-01-01

    This study investigated the effect of bergamot essential oil (BEO) or linalool, a major volatile component of BEO, on the nociceptive response to formalin. Plantar subcutaneous injection of BEO or linalool into the ipsilateral hindpaw reduced both the first and late phases of the formalin-induced licking and biting responses in mice. Plantar subcutaneous injection of BEO or linalool into the contralateral hindpaw did not yield an antinociceptive effect, suggesting that the antinociceptive effect of BEO or linalool in the formalin test occurred peripherally. Intraperitoneal and plantar subcutaneous injection pretreatment with naloxone hydrochloride, an opioid receptor antagonist, significantly attenuated both BEO- and linalool-induced antinociception. Pretreatment with naloxone methiodide, a peripherally acting opioid receptor antagonists, also significantly antagonized the antinociceptive effects of BEO and linalool. Our results provide evidence for the involvement of peripheral opioids in antinociception induced by BEO and linalool. These results suggest that activation of peripheral opioid receptors may play an important role in reducing formalin-induced nociception. PMID:25749150

  11. Antitussive activity of Withania somnifera and opioid receptors.

    PubMed

    Nosálová, Gabriela; Sivová, Veronika; Ray, Bimalendu; Fraňová, Soňa; Ondrejka, Igor; Flešková, Dana

    2015-01-01

    Arabinogalactan is a polysaccharide isolated from the roots of the medicinal plant Withania somnifera L. It contains 65% arabinose and 18% galactose. The aim of the present study was to evaluate the antitussive activity of arabinogalactan in conscious, healthy adult guinea pigs and the role of the opioid pathway in the antitussive action. A polysaccharide extract was given orally in a dose of 50 mg/kg. Cough was induced by an aerosol of citric acid in a concentration 0.3 mol/L, generated by a jet nebulizer into a plethysmographic chamber. The intensity of cough response was defined as the number of cough efforts counted during a 3-min exposure to the aerosol. The major finding was that arabinogalactan clearly suppressed the cough reflex; the suppression was comparable with that of codeine that was taken as a reference drug. The involvement of the opioid system was tested with the use of a blood-brain barrier penetrable, naloxone hydrochloride, and non-penetrable, naloxone methiodide, to distinguish between the central and peripheral mu-opioid receptor pathways. Both opioid antagonists acted to reverse the arabinogalactan-induced cough suppression; the reversion was total over time with the latter antagonist. We failed to confirm the presence of a bronchodilating effect of the polysaccharide, which could be involved in its antitussive action. We conclude that the polysaccharide arabinogalactan from Withania somnifera has a distinct antitussive activity consisting of cough suppression and that this action involves the mu-opioid receptor pathways. PMID:25252908

  12. Mechanism of the antagonism by pralidoxime and 1,1-trimethylenebis(4-hydroxyiminomethylpyridinium) of the action of echothiophate on the intestine

    PubMed Central

    Lehman, R. A.

    1962-01-01

    Pralidoxime chloride (pyridine-2-aldoxime methochloride; Protopam Chloride) and 1,1'-trimethylenebis(4-hydroxyiminomethylpyridinium bromide) (TMB-4) antagonize the spasm of the isolated or intact small intestine of the rabbit caused by the anticholinesterase, echothiophate iodide (S-2-dimethylaminoethyl OO-diethyl phosphorothiolate methiodide; Phospholine Iodide). In vitro, both oximes also antagonize the spasm caused by acetylcholine. The quantitative relationships have been studied in comparison with the activity of atropine against echothiophate and acetylcholine. Echothiophate-treated intestine which is subjected to a concentration of oxime sufficient to cause 100% restoration of function (but not cholinesterase reactivation) will go back into spasm on washing out both drugs. Strips treated with a high concentration of oxime, sufficient to cause 100% reactivation of cholinesterase, exhibit normal control tone and motility after washing. It is concluded that pralidoxime and 1,1'-trimethylenebis(4-hydroxyiminomethylpyridinium bromide) have an anticholinergic action as well as the ability to reactivate cholinesterase and that this action plays a significant part in the initial recovery of function under the conditions of these experiments. PMID:14463753

  13. Characterization of scratching behavior induced by intradermal administration of morphine and fentanyl in mice.

    PubMed

    Yamamoto, Atsuki; Kuyama, Shoji; Kamei, Chiaki; Sugimoto, Yukio

    2010-02-10

    Itching is known as a commonly side effect of opioid administration. However, the relationship of opioid receptors to itching is unclear. In this study, we examined the effect of intradermal injection of morphine and fentanyl on the itching sensation. When injected intradermally into the rostral back of mice, morphine and fentanyl elicited scratching behavior. In addition, an opioid receptor antagonist, naloxone, and a peripherally restricted opioid receptor antagonist, naloxone methiodide, significantly suppressed morphine- and fentanyl-induced scratching behavior. Moreover, the morphine-induced scratching behavior was suppressed by histamine H(1) receptor antagonists, such as diphenhydramine, chlorpheniramine, epinastine and cetirizine. On the other hand, fentanyl-induced scratching behavior was not suppressed by histamine H(1) receptor antagonists. Additionally, scratching behavior induced by morphine and fentanyl were not suppressed by glucocorticoids (predonisolone and dexamethasone). In conclusion, opioid-induced itching may involve in peripheral opioid receptors. Moreover, histamine and arachidonic acid metabolites played no main role in opioid-induced scratching behavior. PMID:19900440

  14. [Inhibition of prostaglandins synthesis in the inflamed site results in opioid-mediated hypoalgesia in rats].

    PubMed

    Huang, Jian; Wu, Jian; Yang, Huai-Zu; Hong, Yanguo

    2016-06-25

    This study was designed to investigate the contribution of prostaglandins to the maintenance of inflammatory pain. Inflammation was induced by intraplantar (i.pl.) injection of carrageenan in right hindpaw in rats. Indomethacin (non-selective COX inhibitor) was administered i.pl. 1 h after the carrageenan injection, and paw withdrawal latency (PWL) responding to noxious heat was measured. β-endorphin (β-END) and μ-opioid receptor (MOR) expressed in the inflamed site were examined by using immunocytochemistry, ELISA and RT-PCR techniques. The results showed that indomethacin dose-dependently increased PWL to the levels that were above the baseline on the day 2 and 3, referred to as hypoalgesia. The hypoalgesia was abolished by a local injection of the non-selective opioid receptor inhibitor naloxone methiodide. The number of β-END-positive cells, the content of β-END and the expression of MOR mRNA in the inflammatory site of inflammation model rats were all significantly increased by indomethacin. These results reveal a novel mechanism of prostaglandins for the inhibition of inflammation-induced endogenous opioid activity. This study provides further evidence that inhibition of prostaglandins in inflamed site could be a promising therapy for inflammatory pain. PMID:27350196

  15. Muscarinic cholinergic receptor in the human heart evidenced under physiological conditions by positron emission tomography.

    PubMed Central

    Syrota, A; Comar, D; Paillotin, G; Davy, J M; Aumont, M C; Stulzaft, O; Maziere, B

    1985-01-01

    The muscarinic receptor was studied in vivo in the human heart by a noninvasive method, positron emission tomography (PET). The study showed that the binding sites of 11C-labeled methiodide quinuclidinyl benzilate [( 11C]-MQNB), a muscarinic antagonist, were mainly distributed in the ventricular septum (98 pmol/cm3 of heart) and in the left ventricular wall (89 pmol/cm3), while the atria were not visualized. A few minutes after a bolus intravenous injection, the concentration of [11C]MQNB in blood fell to a negligible level (less than 100th of the concentration measured in the ventricular septum). When injected at high specific radioactivity, the concentration of [11C]MQNB in the septum rapidly increased and then remained constant with time. This result was explained by rebinding of the ligand to receptors. It was the major difference observed between the kinetics of binding of [11C]MQNB to receptor sites after intravenous injection in vivo and that of [3H]MQNB to heart homogenates in vitro. The MQNB concentrations in the ventricular septum of different individuals were found to be highest when the heart rate at the time of injection was slow. This result suggests that the antagonist binding site is related to a low-affinity conformational state of the receptor under predominant vagal stimulation. Thus, positron emission tomography might be the ideal method to study the physiologically active form of the muscarinic acetylcholine receptor in man. Images PMID:3871527

  16. M3 muscarinic receptors promote cell survival through activation of the extracellular regulated kinase (ERK1/2) pathway.

    PubMed

    Greenwood, Jeffrey M; Dragunow, Michael

    2010-08-25

    Activation of certain subtypes of the muscarinic acetylcholine receptor can enhance cell survival. In SK-N-SH human neuroblastoma cells, muscarinic acetylcholine receptor activation induces phosphorylation of CREB and induction of EGR1, transcription factors associated with cell growth and survival. We identified the M3 muscarinic acetylcholine receptor subtype as being primarily responsible for these transcription factor responses after stimulation with carbachol, using subtype-preferring receptor antagonists and muscarinic snake toxins. In a cell survival/death model in SK-N-SH cells deprived of serum growth factors, carbachol increased cell viability, an effect blocked by the non-specific muscarinic antagonist atropine and the M3-preferring antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), suggesting that the M3 receptor is also driving the survival response in these cells. This cytoprotection is largely dependent on activation of the p44/42 extracellular regulated kinase (ERK1/2) pathway. Understanding such survival signalling pathways is important for both potential interventions in neurodegenerative disease and for targeting neuroblastoma and malignancies of the central nervous system. PMID:20519144

  17. Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats.

    PubMed

    Henderson, Fraser; May, Walter J; Gruber, Ryan B; Discala, Joseph F; Puskovic, Veljko; Young, Alex P; Baby, Santhosh M; Lewis, Stephen J

    2014-01-15

    This study determined the effects of the peripherally restricted μ-opiate receptor (μ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25μg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5mg/kg of NLXmi but was attenuated by a 5.0mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral μ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. PMID:24284037

  18. Increased GABA(A) inhibition of the RVLM after hindlimb unloading in rats

    NASA Technical Reports Server (NTRS)

    Moffitt, Julia A.; Heesch, Cheryl M.; Hasser, Eileen M.

    2002-01-01

    Attenuated baroreflex-mediated increases in renal sympathetic nerve activity (RSNA) in hindlimb unloaded (HU) rats apparently are due to changes within the central nervous system. We hypothesized that GABA(A) receptor-mediated inhibition of the rostral ventrolateral medulla (RVLM) is increased after hindlimb unloading. Responses to bilateral microinjection of the GABA(A) antagonist (-)-bicuculline methiodide (BIC) into the RVLM were examined before and during caudal ventrolateral medulla (CVLM) inhibition in Inactin-anesthetized control and HU rats. Increases in mean arterial pressure (MAP), heart rate (HR), and RSNA in response to BIC in the RVLM were significantly enhanced in HU rats. Responses to bilateral CVLM blockade were not different. When remaining GABA(A) inhibition in the RVLM was blocked by BIC during CVLM inhibition, the additional increases in MAP and RSNA were significantly greater in HU rats. These data indicate that GABA(A) receptor-mediated inhibition of RVLM neurons is augmented after hindlimb unloading. Effects of input from the CVLM were unaltered. Thus, after cardiovascular deconditioning in rodents, the attenuated increase in sympathetic nerve activity in response to hypotension is associated with greater GABA(A) receptor-mediated inhibition of RVLM neurons originating at least in part from sources other than the CVLM.

  19. Stereoselective inhibition of muscarinic receptor subtypes by the enantiomers of hexahydro-difenidol and acetylenic analogues.

    PubMed Central

    Feifel, R.; Wagner-Röder, M.; Strohmann, C.; Tacke, R.; Waelbroeck, M.; Christophe, J.; Mutschler, E.; Lambrecht, G.

    1990-01-01

    1. The affinities of the (R)- and (S)-enantiomers of hexahydro-difenidol (1) and its acetylenic analogues hexbutinol (2), hexbutinol methiodide (3) and p-fluoro-hexbutinol (4) (stereochemical purity greater than 99.8%) for muscarinic receptors in rabbit vas deferens (M1), guinea-pig atria (M2) and guinea-pig ileum (M3) were measured by dose-ratio experiments. 2. The (R)-enantiomers consistently showed higher affinities than the (S)-isomers. The stereoselectivity ratios [(R)/(S)] were greatest with the enantiomers of 1 (vas deferens: 550; ileum: 191; atria: 17) and least with those of the p-Fluoro-analogue 4 (vas deferens: 34; ileum: 8.5; atria: 1.7). 3. The enantiomeric potency ratios for compounds 1-4 were highest in rabbit vas deferens, intermediate in guinea-pig ileum and much less in guinea-pig atria. Thus, these ratios may serve as a predictor of muscarinic receptor subtype identity. 4. (S)-p-Fluoro-hexbutinol [(S)-4] showed a novel receptor selectivity profile with preference for M3 receptors: M3 greater than M2 greater than or equal to M1. 5. These results do not conform to Pfeiffer's rule that activity differences between enantiomers are greater with more potent compounds. PMID:2331578

  20. Binding properties of nine 4-diphenyl-acetoxy-N-methyl-piperidine (4-DAMP) analogues to M1, M2, M3 and putative M4 muscarinic receptor subtypes.

    PubMed Central

    Waelbroeck, M.; Camus, J.; Tastenoy, M.; Christophe, J.

    1992-01-01

    1. We compared the binding properties of 4-diphenyl-acetoxy-N-methyl-piperidine methiodide (4-DAMP) and nine analogues of this compound on muscarinic receptors of human neuroblastoma NB-OK1 cells (M1 subtype), rat heart (M2 subtype), rat pancreas (M3 subtype) and to the putative M4 subtype in striatum. 2. The requirements for high affinity binding were somewhat different for the four receptor subtypes. In general, the requirements of M3 receptors were more stringent than for M1, M2 or putative M4 receptors. 3. The abilities of the compounds to discriminate muscarinic receptor subtypes were not correlated with their affinities at any subtype. 4. The temperature-dependence of binding of 4-DAMP analogues to M2 receptors varied with the drug structure. In particular, the increased affinity of the alpha-methyl derivative of 4-DAMP could be ascribed to van der Waals interactions. 5. The affinities of most 4-DAMP analogues for M2 and M3 receptors were similar to their pharmacological potencies on atrial and ileum preparations, respectively. 6. At concentrations above 1 microM, all 4-DAMP analogues as well as atropine, reduced the [3H]-N-methyl scopolamine ([3H]-NMS) dissociation rate from cardiac muscarinic receptors, with no obvious structure-activity relationship. PMID:1596694

  1. An acetylcholinesterase biosensor for determination of low concentrations of Paraoxon and Dichlorvos.

    PubMed

    Di Tuoro, D; Portaccio, M; Lepore, M; Arduini, F; Moscone, D; Bencivenga, U; Mita, D G

    2011-12-15

    The characterization of an economic and ease-to-use carbon paste acetylcholinesterase (AChE) based biosensor to determine the concentration of pesticides Paraoxon and Dichlorvos is discussed. AChE hydrolyses acetylthiocholine (ATCh) in thiocoline (TC) and acetic acid (AA). When AChE is immobilized into a paste carbon working electrode kept at +410 mV vs. Ag/AgCl electrode, the enzyme reaction rate using acetylthiocholine chloride (ATCl) as substrate is monitored as a current intensity. Because Paraoxon and Dichlorvos inhibit the AChE reaction, the decrease of the current intensity, at fixed ATCl concentration, is a measure of their concentration. Linear calibration curves for Paraoxon and Dichlorvos determination have been obtained. The detection limits resulted to be 0.86 ppb and 4.2 ppb for Paraoxon and Dichlorvos, respectively, while the extension of the linear range was up 23 ppb for the former pesticide and up to 33 ppb for the latter. Because the inhibited enzyme can be reactivated when immediately treated with an oxime, the biosensor reactivation has been studied when 1,1'-trimethylene bis 4-formylpyridinium bromide dioxime (TMB-4) and pyridine 2-aldoxime methiodide (2-PAM) were used. TMB-4 resulted more effective. The comparison with the behavior of similar AChE based biosensors is also presented. PMID:21600321

  2. Possible role of the gamma-aminobutyric acid-A receptor system in the timing of the proestrous luteinizing hormone surge in rats.

    PubMed

    Mitsushima, D; Jinnai, K; Kimura, F

    1997-05-01

    To examine the role of the gamma-aminobutyric acid-A receptor-mediated system in the timing of the proestrous LH surge, we observed the free running activity rhythm and the timing of the LH surge simultaneously in blinded cycling female rats. Blood samples were obtained from unanesthetized freely moving rats through an intraatrial cannula. Five hours after the activity offset on the day of proestrus, bicuculline methiodide (BIC; 50 mg/kg x h) or saline was infused i.v. for 3 h into the freely moving rats. In the BIC group, the peak time of the surge occurred at 7.9 +/- 0.2 h after the activity offset, with a significant advance compared to the peak time in the saline group (i.e. 9.9 +/- 0.4 h), but neither BIC nor saline induced a significant phase shift in the circadian activity rhythm. We found that the infusion of BIC on the subjective morning of the proestrous day dissociates the timing of the LH surge from the circadian activity rhythm in rats. PMID:9112391

  3. Acetylcholinesterase-independent action of diisopropyl-flurophosphate in the rat aorta.

    PubMed

    Lim, S L; Sim, M K; Loke, W K

    2000-09-22

    Recent studies have shown that many organophosphates can bind competitively and noncompetitively to membrane muscarinic receptors. The present study investigated the responses of the rat aortic rings to diisopropyl-flurophosphate (DFP), an organophsophorus cholinesterase inhibitor, and the possible involvement of muscarinic receptors. DFP caused a concentration-dependent contraction when added cumulatively from 10(-8) to 10(-4) M. This contraction was inhibited in a noncompetitive manner by high concentrations of atropine (1.5 x 10(-6) and 1.8 x 10(-6) M) but was unaffected by similar concentrations of selective muscarinic receptor subtype antagonists, pirenzepine, 11-2[2-[(diethylamino)methyl]-1-piperidinyl]acetyl-5, 11-dihydro-6H-rido[2,3-b][1,4]benzodiazepin-6-one (AF-DX116) and 4-Diphenylacetoxy-N-methyl piperidine methiodide (4-DAMP). Phentolamine, an alpha-adrenoceptor antagonist, was able to inhibit the DFP-induced contraction in a noncompetitive manner at a concentration of 10(-7) M. These findings suggested that the DFP-induced contraction in the rat aortic rings was mediated by norepinephrine that was released from sympathetic nerve terminals present in the aortic rings. PMID:10996600

  4. Role of central and peripheral opiate receptors in the effects of fentanyl on analgesia, ventilation and arterial blood-gas chemistry in conscious rats

    PubMed Central

    Henderson, Fraser; May, Walter J.; Gruber, Ryan B.; Discala, Joseph F.; Puscovic, Veljko; Young, Alex P.; Baby, Santhosh M.; Lewis, Stephen J.

    2015-01-01

    This study determined the effects of the peripherally restricted µ-opiate receptor (µ-OR) antagonist, naloxone methiodide (NLXmi) on fentanyl (25 µg/kg, i.v.)-induced changes in (1) analgesia, (2) arterial blood gas chemistry (ABG) and alveolar-arterial gradient (A-a gradient), and (3) ventilatory parameters, in conscious rats. The fentanyl-induced increase in analgesia was minimally affected by a 1.5 mg/kg of NLXmi but was attenuated by a 5.0 mg/kg dose. Fentanyl decreased arterial blood pH, pO2 and sO2 and increased pCO2 and A-a gradient. These responses were markedly diminished in NLXmi (1.5 mg/kg)-pretreated rats. Fentanyl caused ventilatory depression (e.g., decreases in tidal volume and peak inspiratory flow). Pretreatment with NLXmi (1.5 mg/kg, i.v.) antagonized the fentanyl decrease in tidal volume but minimally affected the other responses. These findings suggest that (1) the analgesia and ventilatory depression caused by fentanyl involve peripheral µ-ORs and (2) NLXmi prevents the fentanyl effects on ABG by blocking the negative actions of the opioid on tidal volume and A-a gradient. PMID:24284037

  5. Low-dose morphine elicits ventilatory excitant and depressant responses in conscious rats: Role of peripheral μ-opioid receptors.

    PubMed

    Henderson, Fraser; May, Walter J; Gruber, Ryan B; Young, Alex P; Palmer, Lisa A; Gaston, Benjamin; Lewis, Stephen J

    2013-08-01

    The systemic administration of morphine affects ventilation via a mixture of central and peripheral actions. The aims of this study were to characterize the ventilatory responses elicited by a low dose of morphine in conscious rats; to determine whether tolerance develops to these responses; and to determine the potential roles of peripheral μ-opioid receptors (μ-ORs) in these responses. Ventilatory parameters were monitored via unrestrained whole-body plethysmography. Conscious male Sprague-Dawley rats received an intravenous injection of vehicle or the peripherally-restricted μ-OR antagonist, naloxone methiodide (NLXmi), and then three successive injections of morphine (1 mg/kg) given 30 min apart. The first injection of morphine in vehicle-treated rats elicited an array of ventilatory excitant (i.e., increases in frequency of breathing, minute volume, respiratory drive, peak inspiratory and expiratory flows, accompanied by decreases in inspiratory time and end inspiratory pause) and inhibitory (i.e., a decrease in tidal volume and an increase in expiratory time) responses. Subsequent injections of morphine elicited progressively and substantially smaller responses. The pattern of ventilatory responses elicited by the first injection of morphine was substantially affected by pretreatment with NLXmi whereas NLXmi minimally affected the development of tolerance to these responses. Low-dose morphine elicits an array of ventilatory excitant and depressant effects in conscious rats that are subject to the development of tolerance. Many of these initial actions of morphine appear to involve activation of peripheral μ-ORs whereas the development of tolerance to these responses does not. PMID:24900948

  6. Long-lasting oral analgesic effects of N-protected aminophosphinic dual ENKephalinase inhibitors (DENKIs) in peripherally controlled pain

    PubMed Central

    Bonnard, Elisabeth; Poras, Hervé; Nadal, Xavier; Maldonado, Rafael; Fournié-Zaluski, Marie-Claude; Roques, Bernard P

    2015-01-01

    The peripheral endogenous opioid system is critically involved in neuropathic and inflammatory pain generation as suggested by the modulation of opioid receptors expression and enkephalins (ENKs) release observed in these painful conditions. Accordingly, an innovative approach in the treatment of these nocifensive events is to increase and maintain high local concentrations of extracellular pain-evoked ENKs, by preventing their physiological enzymatic inactivation by two Zn metallopeptidases, the neutral endopeptidase (NEP, neprilysin, EC 3.4.24.11) and the neutral aminopeptidase (APN, EC 3.4.11.2). With this aim, new orally active dual ENKephalinase inhibitors (DENKIs) were designed as soluble prodrugs by introducing a N-terminal cleavable carbamate in the previously described aminophosphinic inhibitors. This induces long-lasting antinociceptive responses after oral administration, in various rodent models of inflammatory and neuropathic pain. These responses are mediated through stimulation of peripheral opioid receptors by DENKIs-protected ENKs as demonstrated by naloxone methiodide reversion. In all tested models, the most efficient prodrug 2a (PL265) was active, at least during 150–180 min, after single oral administration of 25–50 mg/kg in mice and of 100–200 mg/kg in rats. In models of neuropathic pain, both hyperalgesia and allodynia were markedly reduced. Interestingly, combination of inactive doses of 2a (PL265) and of the anti-epileptic drug gabapentin had synergistic effect on neuropathic pain. Pharmacokinetic studies of 2a (PL265) in rats show that the active drug is the only generated metabolite produced. These encouraging results have made 2a (PL265) a suitable candidate for clinical development. PMID:25692029

  7. Neuroanatomical Circuitry Mediating the Sensory Impact of Nicotine in the Central Nervous System

    PubMed Central

    Dehkordi, Ozra; Rose, Jed E.; Asadi, Sadegh; Manaye, Kebreten F.; Millis, Richard M.; Jayam-Trouth, Annapurni

    2014-01-01

    Direct actions of nicotine in the CNS appear to be essential for its reinforcing properties. However, activation of nicotinic acetylcholine receptors (nAChRs) on afferent sensory nerve fibers are important components of addiction to, and withdrawal from, cigarette smoking. The present study was to identify the neuroanatomical substrates activated by the peripheral actions of nicotine and to determine whether these sites overlap brain structures stimulated by direct actions of nicotine. Mouse brains were examined by immunohistochemistry for c-Fos protein after intraperitoneal injection of either nicotine (NIC, 30 and 40 µg/kg) and/or nicotine pyrrolidine methiodide (NIC-PM, 20 and 30 µg/kg). NIC-PM induced c-Fos immunoreactivity (IR) at multiple brain sites. In the brainstem, c-Fos IR was detected in locus coeruleus, laterodorsal tegmental nucleus and pedunculotegmental nucleus. In the midbrain, c-Fos IR was observed in areas overlapping the ventral tegmental area (VTA) which includes paranigral nucleus, parainterfascicular nucleus, parabrachial pigmental area and rostral VTA. Other structures of the nicotine brain-reward circuitry activated by NIC-PM included hypothalamus, paraventricular thalamic nucleus, lateral habenular nucleus, hippocampus, amygdala, accumbens nucleus, piriform cortex, angular insular cortex, anterior olfactory nucleus, lateral septal nucleus, bed nucleus of stria terminalis, cingulate and medial prefrontal cortex, olfactory tubercle, medial and lateral orbital cortex. Nicotine, acting through central and peripheral nAChRs, produced c-Fos IR in areas that overlapped NIC-PM induced c-Fos expressing sites. These neuroanatomical data are the first to demonstrate that the CNS structures which are the direct targets of nicotine are also anatomical substrates for the peripheral sensory impact of nicotine. PMID:25223294

  8. The role of GABAergic inhibition in processing of interaural time difference in the owl's auditory system.

    PubMed

    Fujita, I; Konishi, M

    1991-03-01

    The barn owl uses interaural time differences (ITDs) to localize the azimuthal position of sound. ITDs are processed by an anatomically distinct pathway in the brainstem. Neuronal selectivity for ITD is generated in the nucleus laminaris (NL) and conveyed to both the anterior portion of the ventral nucleus of the lateral lemniscus (VLVa) and the central (ICc) and external (ICx) nuclei of the inferior colliculus. With tonal stimuli, neurons in all regions are found to respond maximally not only to the real ITD, but also to ITDs that differ by integer multiples of the tonal period. This phenomenon, phase ambiguity, does not occur when ICx neurons are stimulated with noise. The main aim of this study was to determine the role of GABAergic inhibition in the processing of ITDs. Selectivity for ITD is similar in the NL and VLVa and improves in the ICc and ICx. Iontophoresis of bicuculline methiodide (BMI), a selective GABAA antagonist, decreased the ITD selectivity of ICc and ICx neurons, but did not affect that of VLVa neurons. Responses of VLVa and ICc neurons to unfavorable ITDs were below the monaural response levels. BMI raised both binaural responses to unfavorable ITDs and monaural responses, though the former remained smaller than the latter. During BMI application, ICx neurons showed phase ambiguity to noise stimuli and no longer responded to a unique ITD. BMI increased the response magnitude and changed the temporal discharge patterns in the VLVa, ICc, and ICx. Iontophoretically applied GABA exerted effects opposite to those of BMI, and the effects could be antagonized with simultaneous application of BMI. These results suggest that GABAergic inhibition (1) sharpens ITD selectivity in the ICc and ICx, (2) contributes to the elimination of phase ambiguity in the ICx, and (3) controls response magnitude and temporal characteristics in the VLVa, ICc, and ICx. Through these actions, GABAergic inhibition shapes the horizontal dimension of the auditory receptive

  9. Temporal progression of evoked field potentials in neocortical slices after unilateral hypoxia-ischemia in perinatal rats: Correlation with cortical epileptogenesis.

    PubMed

    Kadam, S D; Dudek, F E

    2016-03-01

    Infarcts of the neonatal cerebral cortex can lead to progressive epilepsy, which is characterized by time-dependent increases in seizure frequency after the infarct and by shifts in seizure-onset zones from focal to multi-focal. Using a rat model of unilateral perinatal hypoxia-ischemia (PHI), where long-term seizure monitoring had previously demonstrated progressive epilepsy, evoked field potentials (EFPs) were recorded in layers II/III of coronal neocortical slices to analyze the underlying time-dependent, network-level alterations ipsilateral vs. contralateral to the infarct. At 3weeks after PHI, EFPs ipsilateral to the infarct were normal in artificial cerebrospinal fluid (ACSF); however, after blocking GABAA receptors with bicuculline methiodide (BMI, 30μM), the slices with an infarct were more hyperexcitable than slices without an infarct. At 3weeks, contralateral PHI slices had responses indistinguishable from controls. Six months after PHI in normal ACSF, both ipsi- and contralateral slices from rats with cortical infarcts showed prolonged afterdischarges, which were only slightly augmented in BMI. These data suggest that the early changes after PHI are localized to the ipsilateral infarcted cortex and masked by GABA-mediated inhibition; however, after 6months, progressive epileptogenesis results in generation of robust bilateral hyperexcitability. Because these afterdischarges were only slightly prolonged by BMI, a time-dependent reduction of GABAergic transmission is hypothesized to contribute to the pronounced hyperexcitability at 6months. These changes in the EFPs coincide with the seizure semiology of the epilepsy and therefore offer an opportunity to study the mechanisms underlying this form of progressive pediatric epilepsy. PMID:26724579

  10. Rapid Sensitization of Physiological, Neuronal, and Locomotor Effects of Nicotine: Critical Role of Peripheral Drug Actions

    PubMed Central

    Lenoir, Magalie; Tang, Jeremy S.; Woods, Amina S.

    2013-01-01

    Repeated exposure to nicotine and other psychostimulant drugs produces persistent increases in their psychomotor and physiological effects (sensitization), a phenomenon related to the drugs' reinforcing properties and abuse potential. Here we examined the role of peripheral actions of nicotine in nicotine-induced sensitization of centrally mediated physiological parameters (brain, muscle, and skin temperatures), cortical and VTA EEG, neck EMG activity, and locomotion in freely moving rats. Repeated injections of intravenous nicotine (30 μg/kg) induced sensitization of the drug's effects on all these measures. In contrast, repeated injections of the peripherally acting analog of nicotine, nicotine pyrrolidine methiodide (nicotinePM, 30 μg/kg, i.v.) resulted in habituation (tolerance) of the same physiological, neuronal, and behavioral measures. However, after repeated nicotine exposure, acute nicotinePM injections induced nicotine-like physiological responses: powerful cortical and VTA EEG desynchronization, EMG activation, a large brain temperature increase, but weaker hyperlocomotion. Additionally, both the acute locomotor response to nicotine and nicotine-induced locomotor sensitization were attenuated by blockade of peripheral nicotinic receptors by hexamethonium (3 mg/kg, i.v.). These data suggest that the peripheral actions of nicotine, which precede its direct central actions, serve as a conditioned interoceptive cue capable of eliciting nicotine-like physiological and neural responses after repeated nicotine exposure. Thus, by providing a neural signal to the CNS that is repeatedly paired with the direct central effects of nicotine, the drug's peripheral actions play a critical role in the development of nicotine-induced physiological, neural, and behavioral sensitization. PMID:23761889

  11. Contribution of Central μ-Receptors to Switching Pulmonary C-Fibers-Mediated Rapid Shallow Breathing into An Apnea by Fentanyl in Anesthetized Rats

    PubMed Central

    Zhang, Zhenxiong; Zhang, Cancan; Zhuang, Jianguo; Xu, Fadi

    2012-01-01

    Our previous study has shown that activating peripheral μ-receptors is necessary for switching the bronchopulmonary C-fibers (PCFs)-mediated rapid shallow breathing (RSB) into an apnea by systemic administration of fentanyl. The brainstem nuclei, such as the medial nucleus tractus solitarius (mNTS) and the Pre-Botzinger Complex (PBC), are required for completing the PCF-mediated respiratory reflexes. Moreover, these areas contain abundant μ-receptors and their activation prolongs expiratory duration (TE). Thus, we asked if central μ-receptors, especially those in the mNTS and PBC, are involved in fully expressing this RSB-apnea switch by fentanyl. In anesthetized rats, the cardiorespiratory responses to right atrial injection of phenylbiguanide (PBG, 3–6 μg/kg) were repeated after: 1) fentanyl (iv), a μ-receptor agonist, alone (8 μg/kg, iv); 2) fentanyl following microinjection of naloxone methiodide (NXM, an opioid receptor antagonist) into the cisterna magna (10 μg/4 μl); 3) the bilateral mNTS (10 mM, 20 nl); or 4) PBC (10 mM, 20 nl). Our results showed that PBG shortened TE by 37 ± 6 % (RSB, from 0.41 ± 0.05 to 0.26 ± 0.03 s, P < 0.01), but it markedly prolonged TE by 5.8-fold (an apnea, from 0.50 ± 0.04 s to 2.9 ± 0.57 s, P < 0.01) after fentanyl (iv). Pretreatment with NXM injected into the cisterna magna or the PBC, but not the mNTS, prevented the fentanyl-induced switch. This study, along with our previous results mentioned above, suggests that although peripheral μ-receptors are essential for triggering the fentanyl-induced switch, central μ-receptors, especially those in the PBC, are required to fully exhibit such switch. PMID:22759907

  12. Muscarinic acetylcholine receptor modulation of mu (mu) opioid receptors in adult rat sphenopalatine ganglion neurons.

    PubMed

    Margas, Wojciech; Mahmoud, Saifeldin; Ruiz-Velasco, Victor

    2010-01-01

    The sphenopalatine ganglion (SPG) neurons represent the parasympathetic branch of the autonomic nervous system involved in controlling cerebral blood flow. In the present study, we examined the coupling mechanism between mu (mu) opioid receptors (MOR) and muscarinic acetylcholine receptors (mAChR) with Ca(2+) channels in acutely dissociated adult rat SPG neurons. Successful MOR activation was recorded in approximately 40-45% of SPG neurons employing the whole cell variant of the patch-clamp technique. In addition, immunofluorescence assays indicated that MOR are not expressed in all SPG neurons while M(2) mAChR staining was evident in all neurons. The concentration-response relationships generated with morphine and [d-Ala2-N-Me-Phe4-Glycol5]-enkephalin (DAMGO) showed IC(50) values of 15.2 and 56.1 nM and maximal Ca(2+) current inhibition of 26.0 and 38.7%, respectively. Activation of MOR or M(2) mAChR with morphine or oxotremorine-methiodide (Oxo-M), respectively, resulted in voltage-dependent inhibition of Ca(2+) currents via coupling with Galpha(i/o) protein subunits. The acute prolonged exposure (10 min) of neurons to morphine or Oxo-M led to the homologous desensitization of MOR and M(2) mAChR, respectively. The prolonged stimulation of M(2) mAChR with Oxo-M resulted in heterologous desensitization of morphine-mediated Ca(2+) current inhibition, and was sensitive to the M(2) mAChR blocker methoctramine. On the other hand, when the neurons were exposed to morphine or DAMGO for 10 min, heterologous desensitization of M(2) mAChR was not observed. These results suggest that in rat SPG neurons activation of M(2) mAChR likely modulates opioid transmission in the brain vasculature to adequately maintain cerebral blood flow. PMID:19889856

  13. A new enzymic method for the isolation and culture of human bladder body smooth muscle cells.

    PubMed

    Ma, F -H; Higashira, H; Ukai, Y; Hanai, T; Kiwamoto, H; Park, Y C; Kurita, T

    2002-01-01

    Cultured cells of the human urinary bladder smooth muscle are useful for investigating bladder function, but methods for culturing them are not well developed. We have now established a novel enzymic technique. The smooth muscle layer was separated out and incubated with 0.2% trypsin for 30 min at 37 degrees C. The samples were then minced and incubated with 0.1% collagenase for 30 min and centrifuged at 900 g. The pellets were resuspended in RPMI-1640 medium containing 10% fetal calf serum (FCS) and centrifuged at 250 g. The smooth muscle cells from the supernatant were cultured in RPMI-1640 containing 10% FCS. The cells grew to confluence after 7-10 days, forming the "hills and valleys" growth pattern characteristic of smooth muscle cells. Immunostaining with anti-alpha-actin, anti-myosin, and anti-caldesmon antibodies demonstrated that 99% of the cells were smooth muscle cells. To investigate the pharmacological properties of the cultured cells, we determined the inhibitory effect of muscarinic receptor antagonists on the binding of [3H]N-methylscopolamine to membranes from cultured cells. The pKi values obtained for six antagonists agreed with the corresponding values for transfected cells expressing the human muscarinic M2 subtype. Furthermore, carbachol produced an increase in the concentration of cytoplasmic free Ca2+ an action that was blocked by 4-diphenylacetoxy-N-methylpiperidine methiodide, an M3 selective antagonist. This result suggests that these cells express functional M3 muscarinic receptors, in addition to M2 receptors. The subcultured cells therefore appear to be unaffected by our new isolation method. PMID:11835427

  14. 2-Deoxy-D-glucose-induced hypothermia in anesthetized rats: Lack of forebrain contribution and critical involvement of the rostral raphe/parapyramidal regions of the medulla oblongata.

    PubMed

    Osaka, Toshimasa

    2015-07-01

    Systemic or central administration of 2-deoxy-d-glucose (2DG), a competitive inhibitor of glucose utilization, induces hypothermia in awake animals and humans. This response is mediated by the central nervous system, though the neural mechanism involved is largely unknown. In this study, I examined possible involvement of the forebrain, which contains the hypothalamic thermoregulatory center, and the medullary rostral raphe/parapyramidal regions (rRPa/PPy), which mediate hypoxia-induced heat-loss responses, in 2DG-induced hypothermia in urethane-chloralose-anesthetized, neuromuscularly blocked, artificially ventilated rats. The intravenous injection of 2DG (250mgkg(-1)) elicited an increase in tail skin temperature and decreases in body core temperature and the respiratory exchange ratio, though it did not induce any significant change in the metabolic rate. These results indicate that the hypothermic response was caused by an increase in heat loss, but not by a decrease in heat production and that it was accompanied by a decrease in carbohydrate utilization and/or an increase in lipid utilization as energy substrates. Complete surgical transection of the brainstem between the hypothalamus and the midbrain had no effect on the 2DG-induced hypothermic responses, suggesting that the hindbrain, but not the forebrain, was sufficient for the responses. However, pretreatment of the rRPa/PPy with the GABAA receptor blocker bicuculline methiodide, but not with vehicle saline, greatly attenuated the 2DG-induced responses, suggesting that the 2DG-induced hypothermia was mediated, at least in part, by GABAergic neurons in the hindbrain and activation of GABAA receptors on cutaneous sympathetic premotor neurons in the rRPa/PPy. PMID:26146232

  15. Hypothalamic oxytocin attenuates CRF expression via GABA(A) receptors in rats.

    PubMed

    Bülbül, Mehmet; Babygirija, Reji; Cerjak, Diana; Yoshimoto, Sazu; Ludwig, Kirk; Takahashi, Toku

    2011-04-28

    Centrally released oxytocin (OXT) has anxiolytic and anti-stress effects. Delayed gastric emptying (GE) induced by acute restraint stress (ARS) for 90 min is completely restored following 5 consecutive days of chronic homotypic restraint stress (CHS), via up-regulating hypothalamic OXT expression in rats. However, the mechanism behind the restoration of delayed GE following CHS remains unclear. Gamma-aminobutyric acid (GABA)-projecting neurons in the paraventricular nucleus (PVN) have been shown to inhibit corticotropin releasing factor (CRF) synthesis via GABA(A) receptors. We hypothesized that GABA(A) receptors are involved in mediating the inhibitory effect of OXT on CRF expression in the PVN, which in turn restores delayed GE following CHS. OXT (0.5 μg) and selective GABA(A) receptor antagonist, bicuculline methiodide (BMI) (100 ng), were administered intracerebroventricularly (icv). Solid GE was measured under non-stressed (NS), ARS and CHS conditions. Expression of CRF mRNA in the PVN was evaluated by real time RT-PCR. Neither OXT nor BMI changed GE and CRF mRNA expression under NS conditions. Delayed GE and increased CRF mRNA expression induced by ARS were restored by icv-injection of OXT. The effects of OXT on delayed GE and increased CRF mRNA expression in ARS were abolished by icv-injection of BMI. Following CHS, delayed GE was completely restored in saline (icv)-injected rats, whereas daily injection of BMI (icv) attenuated the restoration of delayed GE. Daily injection of BMI (icv) significantly increased CRF mRNA expression following CHS. It is suggested that central OXT inhibits ARS-induced CRF mRNA expression via GABA(A) receptors in the PVN. GABAergic system is also involved in OXT-mediated adaptation response of delayed GE under CHS conditions. PMID:21382355

  16. Defense-like behaviors evoked by pharmacological disinhibition of the superior colliculus in the primate

    PubMed Central

    DesJardin, Jacqueline T.; Holmes, Angela L.; Forcelli, Patrick A.; Cole, Claire E.; Gale, John T.; Wellman, Laurie L.; Gale, Karen; Malkova, Ludise

    2012-01-01

    Stimulation of the intermediate and deep layers of superior colliculus (DLSC) in rodents evokes both tracking/pursuit (approach) and avoidance/flight (defensive) responses (Dean et al., 1989). These two classes of response are subserved by distinct output projections associated with lateral (approach) and medial (defensive) DLSC (Comoli et al., 2012). In nonhuman primates, DLSC has been examined only with respect to orienting/approach behaviors, especially eye movements, however, defense-like behaviors have not been reported. Here we examined the profile of behavioral responses to the activation of DLSC by unilateral intracerebral infusions of the GABAA receptor antagonist, bicuculline methiodide (BIC), in nine freely moving macaques. Across animals, the most consistently evoked behavior was cowering (all animals), followed by increased vocalization and escape-like behaviors (seven animals), and attack of objects (three animals). The effects of BIC were dose-dependent within the range 2.5-14nmol (threshold dose of 4.6nmol). The behaviors and their latency to onset did not vary across different infusion sites within DLSC. Cowering and escape-like behaviors resembled the defense-like responses reported after DLSC stimulation in rats, but in the macaques these responses were evoked from both medial and lateral sites within DLSC. Our findings are unexpected in the context of an earlier theoretical perspective (Dean et al., 1989) that emphasized a preferential role of the primate DLSC for approach rather than defensive responses. Our data provide the first evidence for induction of defense-like behaviors by activation of DLSC in monkeys, suggesting that the role of DLSC in responding to threats is conserved across species. PMID:23283329

  17. The effect of atropine on the activation of 5-hydroxytryptamine3 channels in rat nodose ganglion neurons.

    PubMed

    Fan, P; Weight, F F

    1994-10-01

    It has been suggested that changes in brain 5-hydroxytryptamine3 receptor function may contribute to some behavior disorders, such as anxiety, schizophrenia and drug abuse. We are using the whole-cell version of the patch-clamp technique to study the function of 5-hydroxytryptamine3 channels in neurons freshly dissociated from rat nodose ganglion. In these cells, 5-hydroxytryptamine elicits an inward current over the concentration range of 0.25-100 microM (EC50 = 2.62 microM) by activating 5-hydroxytryptamine3 receptors. The muscarinic cholinergic antagonist atropine reduced the amplitude of 5-hydroxytryptamine activated inward current in a concentration-dependent manner. Other muscarinic antagonists, scopolamine, dexetimide, the M1 muscarinic receptor antagonist pirenzepine, the M2 receptor antagonist methoctramine and the M3 receptor antagonist 4-DAMP methiodide also inhibited 5-hydroxytryptamine-induced inward current. Atropine did not appear to change the reversal potential of this current. In the presence of 5 microM atropine, the concentration-response curve for 5-hydroxytryptamine current was shifted to the right in a parallel fashion. The EC50 value for 5-hydroxytryptamine was increased from 2.62 to 8.76 microM. Schild plots of increasing atropine and 5-hydroxytryptamine concentrations revealed a pA2 value of 5.74 for atropine (apparent KD = 1.8 microM). These observations suggest that atropine competitively antagonizes the activation of a receptor for the neurotransmitter serotonin, a novel action of muscarinic antagonists in the nervous system. This effect of atropine may contribute to the clinical symptoms seen in severe atropine intoxication. PMID:7531305

  18. Amygdala priming results in conditioned place avoidance.

    PubMed

    Thielen, Shelley K; Shekhar, Anantha

    2002-03-01

    Priming involves daily stimulation of the basolateral nucleus of the amygdala (BLA) for 5 days using a dose of the GABA(A) receptor antagonist, bicuculline methiodide (BMI), that is subthreshold to generate anxiogenic-like responses. The coordinated physiological and behavioral response of the primed rat is similar to the symptoms of human panic disorder and has been used as a model to study panic attacks. If the priming procedure is indeed similar to human panic disorder, then the context in which priming occurs should become associated with aversive conditioning and avoidance as seen in secondary agoraphobia following panic attacks in humans. Therefore, the purpose of this study was to further characterize the behavioral response of priming using the conditioned place avoidance (CPA) task that utilizes distinct tactile cues of a grid floor (Grid+) or hole floor (Grid-). Male Wistar rats (275-300 g) were implanted bilaterally with guide cannulae positioned 1 mm above the BLA. Grid+ animals were placed in the conditioning chamber containing grid floors immediately after a 6-pmol (in 250 nl) BMI injection into the BLA and on hole floors following a sham (250 nl vehicle) injection. Grid animals were placed in the chamber containing hole floors after the BMI injection and on grid floors following the sham injection. Animals were placed in the chamber for 20 min following each injection and injections were separated by 4 h. After 5 days of this treatment, the animals were primed. Two days later, during avoidance testing, each animal was placed in the chamber containing both floors for 30 min. Priming with daily 6-pmol BMI injections into the BLA results in CPA or an aversion to the floor paired with the BMI injection. These results suggest that priming may result in phobic-like responses, similar to the avoidance behavior exhibited by panic disorder patients. PMID:11830174

  19. The role of peripheral Na(+) channels in triggering the central excitatory effects of intravenous cocaine.

    PubMed

    Brown, P Leon; Kiyatkin, Eugene A

    2006-08-01

    While alterations in dopamine (DA) uptake appear to be a critical mechanism underlying locomotor and reinforcing effects of cocaine (COC), many centrally mediated physiological and affective effects of this drug are resistant to DA receptor blockade and are expressed more quickly following an intravenous (i.v.) injection than expected based on the dynamics of drug concentration in the brain. Because COC is also a potent local anesthetic, its rapid action on Na+ channels may be responsible for triggering these effects. We monitored temperatures in the nucleus accumbens, temporal muscle and skin together with conventional locomotion during a single i.v. injection of COC (1 mg/kg), procaine (PRO, 5 mg/kg; equipotential anesthetic dose), a short-acting local anesthetic drug that, like COC, interacts with Na+ channels, and cocaine methiodide (COC-MET, 1.31 mg/kg, equimolar dose), a quaternary COC derivative that is unable to cross the blood-brain barrier. In this way, we explored not only the importance of Na+ channels in general, but also the importance of central vs. peripheral Na+ channels specifically. COC induced locomotor activation, temperature increase in the brain and muscle, and a biphasic temperature fluctuation in skin. Though PRO did not induce locomotor activation, it mimicked, to a greater degree, the temperature effects of COC. Therefore, Na+ channels appear to be a key substrate for COC-induced temperature fluctuations in the brain and periphery. Similar to PRO, COC-MET had minimal effects on locomotion, but mimicked COC in its ability to increase brain and muscle temperature, and induce transient skin hypothermia. It appears therefore that COC's interaction with peripherally located Na+ channels triggers its central excitatory effects manifested by brain temperature increase, thereby playing a major role in drug sensing and possibly contributing to COC reinforcement. PMID:16930444

  20. Hippocampal Extracellular Signal-Regulated Kinase Signaling has a Role in Passive Avoidance Memory Retrieval Induced by GABAA Receptor Modulation in Mice

    PubMed Central

    Kim, Dong Hyun; Kim, Jong Min; Park, Se Jin; Lee, Seungheon; Shin, Chan Young; Cheong, Jae Hoon; Ryu, Jong Hoon

    2012-01-01

    Available evidence strongly suggests that the γ-aminobutyric acid type A (GABAA) receptor has a crucial role in memory retrieval. However, the signaling mechanisms underlying the role of GABAA receptor modulation in memory retrieval are unclear. We conducted one-trial passive avoidance task with pre-retention trial drug administration in the hippocampus to test the effects of GABAA receptor modulation on memory retrieval. We further tested the co-involvement of signaling molecules: extracellular signal-regulated kinase (ERK), Ca2+/calmodulin-dependent protein kinase II (CaMKII), and cAMP responsive element-binding protein (CREB). First, we observed that the phosphorylation of hippocampal ERK was required for memory retrieval during the task. Accordingly, to investigate whether GABAA receptor activation or inhibition induces ERK phosphorylation during memory retrieval, drugs that target the GABAA receptor were administered into the hippocampus before the retention trial. Muscimol, a GABAA receptor agonist, and diazepam, an agonist to benzodiazepine-binding site of GABAA receptor, blocked retention trial-induced ERK phosphorylation and impaired memory retrieval. Furthermore, co-treatment with sub-effective dose of U0126, a mitogen-activated protein kinase inhibitor, blocked the upregulation of ERK phosphorylation and impaired memory retrieval, and bicuculline methiodide (BMI), a GABAA receptor antagonist, increased ERK phosphorylation induced by the retention trial and facilitated memory retrieval. Finally, the effects of BMI were blocked by the co-application of a sub-effective dose of U0126. These results suggest that GABAA receptor-mediated memory retrieval is closely related to ERK activity. PMID:22169949

  1. Enzymatic specificities and modes of action of the two catalytic domains of the XynC xylanase from Fibrobacter succinogenes S85.

    PubMed Central

    Zhu, H; Paradis, F W; Krell, P J; Phillips, J P; Forsberg, C W

    1994-01-01

    The xylanase XynC of Fibrobacter succinogenes S85 was recently shown to contain three distinct domains, A, B, and C (F. W. Paradis, H. Zhu, P. J. Krell, J. P. Phillips, and C. W. Forsberg, J. Bacteriol. 175:7666-7672, 1993). Domains A and B each bear an active site capable of hydrolyzing xylan, while domain C has no enzymatic activity. Two truncated proteins, each containing a single catalytic domain, named XynC-A and XynC-B were purified to homogeneity. The catalytic domains A and B had similar pH and temperature parameters of 6.0 and 50 degrees C for maximum hydrolytic activity and extensively degraded birch wood xylan to xylose and xylobiose. The Km and Vmax values, respectively, were 2.0 mg ml-1 and 6.1 U mg-1 for the intact enzyme, 1.83 mg ml-1 and 689 U mg-1 for domain A, and 2.38 mg ml-1 and 91.8 U mg-1 for domain B. Although domain A had a higher specific activity than domain B, domain B exhibited a broader substrate specificity and hydrolyzed rye arabinoxylan to a greater extent than domain A. Furthermore, domain B, but not domain A, was able to release xylose at the initial stage of the hydrolysis. Both catalytic domains cleaved xylotriose, xylotetraose, and xylopentaose but had no activity on xylobiose. Bond cleavage frequencies obtained from hydrolysis of xylo-alditol substrates suggest that while both domains have a strong preference for internal linkages of the xylan backbone, domain B has fewer subsites for substrate binding than domain A and cleaves arabinoxylan more efficiently. Chemical modification with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide methiodide and N-bromosuccinimide inactivated both XynC-A and XynC-B in the absence of xylan, indicating that carboxyl groups and tryptophan residues in the catalytic site of each domain have essential roles. Images PMID:8021170

  2. Nuclear medicine progress report for quarter ending September 30, 1984

    SciTech Connect

    Knapp, F.F. Jr.; Ambrose, K.R.; Goodman, M.M.; Srivastava, P.C.

    1984-12-01

    The preparation and animal testing of a new radio-iodinated p-iodophenylamine-linked dihydropyridine system is described. The model agent, 1-methyl-3-(N-(..beta..-(4-(/sup 125/I)iodophenyl)ethyl)carbamoyl)-1,4-dihydropyridine, was prepared by coupling 4-(/sup 125/I)iodoaniline with the methiodide salt succinimidyl ester of nicotinic acid followed by dithionite reduction to the lipid soluble product. The dihydropyridine agent showed good brain uptake in rats (5 min, 1.14% injected dose/gm; 60 min, 1.12% dose/gm) and good brain to blood ratios (5 min 3.9:1, 60 min, 3.5:1). In contrast the quaternary ammonium compound, prior to reduction, showed only moderate brain uptake (5 min, 0.63; 60 min, 0.46) and low brain to blood ratios (5 min, 0.05; 60 min, 0.06). Also described is further investigation of the effects of fasting on the relative myocardial retention of straight-chain iodovinyl fatty acids. 18-(/sup 125/)Iodo-17-octadecenoic acid showed good retention in unfasted rats. Studies have now been reported for fasted rats where this agent showed rapid myocardial wash-out. In fasted rats, approx. 70% wash-out at 30 min, and in unfasted rats, approx. 15% wash-out at 30 min was observed. During this period several shipments were made to Medical Cooperative investigators including three samples of /sup 191/Os-potassium osmate (Children's Hospital, Boston, and the University of Liege, Belgium) and 15-(p-(/sup 131/I)iodophenyl)-3-R,S-methylpentadecanoic acid (University of Massachusetts and Brookhaven National Laboratory).

  3. Evidence for a peripheral mechanism in cardiac opioid withdrawal.

    PubMed

    Milanés, M V; Martinez, M D; González-Cuello, A; Laorden, M L

    2001-09-01

    Studies involving heart catecholaminergic systems in morphine-dependent rats have not established whether the adaptive changes observed in the heart during morphine withdrawal are mediated peripherally or centrally. In this study, naloxone (Nx), naloxone methiodide (NxM) and N-methyl levallorphan (NML), quaternary derivatives of Nx and levallorphan, respectively, that do not cross the blood-brain barrier, were administered to morphine-dependent rats and catecholamines and their metabolites determined in the right ventricle. Rats were made dependent on morphine by implantation of morphine pellets for 7 days. On day 8 animals received s.c. injections of saline, Nx (1 mg/kg), NxM (5 mg/kg) or NML (5 mg/kg) and were decapitated 30 min later. Noradrenaline (NA) and its metabolites normetanephrine (NMN) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and dopamine (DA) and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) were determined by high-performance liquid chromatography with electrochemical detection. After NxM or NML administration to morphine-dependent rats there was a pronounced increase in NMN and DOPAC levels, as well as in NA and DA turnovers (as estimated by NMN/NA and DOPAC/DA ratios, respectively) in the right ventricle. Similarly, giving Nx to morphine-dependent rats increased NMN and DOPAC levels and NA and DA turnovers. In addition, in the paraventricular nucleus of the hypothalamus (PVN) NA and DA turnover, measured as the MHPG/NA or DOPAC/DA ratios, increased after Nx administration but not after NxM or NML These results suggest that the changes in cardiac sympathetic activity observed during morphine withdrawal are due to intrinsic mechanisms outside the central nervous system. These data may be important for understanding the adaptive changes induced in the heart in subjects dependent on opioids. PMID:11521160

  4. Involvement of nitric oxide in the inhibition of bone cancer-induced hyperalgesia through the activation of peripheral opioid receptors in mice.

    PubMed

    Menéndez, Luis; Juárez, Lucía; García, Verónica; Hidalgo, Agustín; Baamonde, Ana

    2007-07-01

    Experiments were designed to elucidate the involvement of nitric oxide (NO) in the antihyperalgesic effect induced by the activation of peripheral mu-opioid receptors on osteosarcoma-induced thermal hyperalgesia in mice. Since this pathway has previously been shown to be involved in the antihyperalgesic effect induced by some drugs--including opiates--on inflammatory pain, experiments were also performed in inflamed mice. The intraplantar administration of loperamide (15 microg) abolishes the thermal hyperalgesia that appears 4 weeks after the intratibial inoculation of NCTC 2472 cells in C3H/HeJ mice. The blockade of this effect by coadministering a peripheral opioid receptor antagonist (naloxone methiodide), a nitric oxide synthase (NOS) inhibitor (L-NMMA), a soluble guanylyl cyclase inhibitor (ODQ), a PKG inhibitor (KT-5823) or a K(+)(ATP)-channel blocker (glibenclamide) shows the involvement of a NO/cGMP/K(+)(ATP)-channel pathway. Accordingly the administration of loperamide produced, in osteosarcoma-bearing mice, an increase in the concentrations of NO metabolites, nitrites and nitrates, extracted from paws. The selective inhibitor of eNOS L-NIO, but not the inhibitors of nNOS (N-omega-propyl-L-arginine) or iNOS (1400w), blocked the effect of loperamide on osteosarcoma-induced hyperalgesia and also the endogenous opioid peripheral hypoalgesia that appears during the initial stages of the development of this osteosarcoma. Although this pathway also participates in the inhibitory effect of loperamide on the thermal hyperalgesia induced by administration of complete Freund's adjuvant, only selective inhibitors of nNOS or iNOS antagonized this effect. Our results demonstrate that the activation of a NO/cGMP/K(+)(ATP)-channel triggered by eNOS participates in the peripheral antihyperalgesic of loperamide on osteosarcoma-induced thermal hyperalgesia. PMID:17543351

  5. Oxotremorine treatment reduces repetitive behaviors in BTBR T+ tf/J mice

    PubMed Central

    Amodeo, Dionisio A.; Yi, Julia; Sweeney, John A.; Ragozzino, Michael E.

    2014-01-01

    Repetitive behaviors with restricted interests is one of the core criteria for the diagnosis of autism spectrum disorder (ASD). Current pharmacotherapies that target the dopaminergic or serotonergic systems have limited effectiveness in treating repetitive behaviors. Previous research has demonstrated that administration of muscarinic cholinergic receptor (mAChR) antagonists can exacerbate motor stereotypies while mAChR agonists reduce stereotypies. The present study determined whether the mAChR agonist, oxotremorine affected repetitive behaviors in the BTBR T+ tf/J (BTBR) mouse model of autism. To test the effects of oxotremorine on repetitive behaviors, marble burying and grooming behavior were measured in BTBR mice and compared to that in C57BL/6J (B6) mice. The effects of oxotremorine on locomotor activity was also measured. Thirty minutes before each test, mice received an intraperitoneal (ip) injection of saline, 0.001 mg or 0.01 mg of oxotremorine methiodide. Saline- treated BTBR mice exhibited increased marble burying and self-grooming behavior compared to that of saline-treated B6 mice. Oxotremorine significantly reduced marble burying and self-grooming behavior in BTBR mice, but had no significant effect in B6 mice. In addition, oxotremorine did not affect locomotor activity in BTBR mice, but significantly reduced locomotor activity in B6 mice at the 0.01 mg dose. These findings demonstrate that activation of mAChRs reduces repetitive behavior in the BTBR mouse and suggest that treatment with a mAChR agonist may be effective in reducing repetitive behaviors in ASD. PMID:25165445

  6. Central and peripheral contributions to dynamic changes in nucleus accumbens glucose induced by intravenous cocaine

    PubMed Central

    Wakabayashi, Ken T.; Kiyatkin, Eugene A.

    2015-01-01

    The pattern of neural, physiological and behavioral effects induced by cocaine is consistent with metabolic neural activation, yet direct attempts to evaluate central metabolic effects of this drug have produced controversial results. Here, we used enzyme-based glucose sensors coupled with high-speed amperometry in freely moving rats to examine how intravenous cocaine at a behaviorally active dose affects extracellular glucose levels in the nucleus accumbens (NAc), a critical structure within the motivation-reinforcement circuit. In drug-naive rats, cocaine induced a bimodal increase in glucose, with the first, ultra-fast phasic rise appearing during the injection (latency 6–8 s; ~50 μM or ~5% of baseline) followed by a larger, more prolonged tonic elevation (~100 μM or 10% of baseline, peak ~15 min). While the rapid, phasic component of the glucose response remained stable following subsequent cocaine injections, the tonic component progressively decreased. Cocaine-methiodide, cocaine's peripherally acting analog, induced an equally rapid and strong initial glucose rise, indicating cocaine's action on peripheral neural substrates as its cause. However, this analog did not induce increases in either locomotion or tonic glucose, suggesting direct central mediation of these cocaine effects. Under systemic pharmacological blockade of dopamine transmission, both phasic and tonic components of the cocaine-induced glucose response were only slightly reduced, suggesting a significant role of non-dopamine mechanisms in cocaine-induced accumbal glucose influx. Hence, intravenous cocaine induces rapid, strong inflow of glucose into NAc extracellular space by involving both peripheral and central, non-dopamine drug actions, thus preventing a possible deficit resulting from enhanced glucose use by brain cells. PMID:25729349

  7. Inhibition of the mitochondrial unfolded protein response by acetylcholine alleviated hypoxia/reoxygenation-induced apoptosis of endothelial cells.

    PubMed

    Xu, Man; Bi, Xueyuan; He, Xi; Yu, Xiaojiang; Zhao, Ming; Zang, Weijin

    2016-05-18

    The mitochondrial unfolded protein response (UPR(mt)) is involved in numerous diseases that have the common feature of mitochondrial dysfunction. However, its pathophysiological relevance in the context of hypoxia/reoxygenation (H/R) in endothelial cells remains elusive. Previous studies have demonstrated that acetylcholine (ACh) protects against cardiomyocyte injury by suppressing generation of mitochondrial reactive oxygen species (mtROS). This study aimed to explore the role of UPR(mt) in endothelial cells during H/R and to clarify the beneficial effects of ACh. Our results demonstrated that H/R triggered UPR(mt) in endothelial cells, as evidenced by the elevation of heat shock protein 60 and LON protease 1 protein levels, and resulted in release of mitochondrial pro-apoptotic proteins, including cytochrome C, Omi/high temperature requirement protein A 2 and second mitochondrial activator of caspases/direct inhibitor of apoptosis-binding protein with low PI, from the mitochondria to cytosol. ACh administration markedly decreased UPR(mt) by inhibiting mtROS and alleviating the mitonuclear protein imbalance. Consequently, ACh alleviated the release of pro-apoptotic proteins and restored mitochondrial ultrastructure and function, thereby reducing the number of terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL)-positive cells. Intriguingly, 4-diphenylacetoxy-N-methylpiperidine methiodide, a type-3 muscarinic ACh receptor (M3AChR) inhibitor, abolished the ACh-elicited attenuation of UPR(mt) and TUNEL positive cells, indicating that the salutary effects of ACh were likely mediated by M3AChR in endothelial cells. In conclusion, our studies demonstrated that UPR(mt) might be essential for triggering the mitochondrion-associated apoptotic pathway during H/R. ACh markedly suppressed UPR(mt) by inhibiting mtROS and alleviating the mitonuclear protein imbalance, presumably through M3AChR. PMID:27111378

  8. Acetylcholine ameliorates endoplasmic reticulum stress in endothelial cells after hypoxia/reoxygenation via M3 AChR-AMPK signaling.

    PubMed

    Bi, Xueyuan; He, Xi; Xu, Man; Zhao, Ming; Yu, Xiaojiang; Lu, Xingzhu; Zang, Weijin

    2015-08-01

    Endoplasmic reticulum (ER) stress is associated with various cardiovascular diseases. However, its pathophysiological relevance and the underlying mechanisms in the context of hypoxia/reoxygenation (H/R) in endothelial cells are not fully understood. Previous findings have suggested that acetylcholine (ACh), the major vagal nerve neurotransmitter, protected against cardiomyocyte injury by activating AMP-activated protein kinase (AMPK). This study investigated the role of ER stress in endothelial cells during H/R and explored the beneficial effects of ACh. Our results showed that H/R triggered ER stress and apoptosis in endothelial cells, evidenced by the elevation of glucose-regulated protein 78, cleaved caspase-12 and C/EBP homologous protein expression. ACh significantly decreased ER stress and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling positive cells and restored ER ultrastructural changes induced by H/R, possibly via protein kinase-like ER kinase and inositol-requiring kinase 1 pathways. Additionally, 4-diphenylacetoxy-N-methylpiperidine methiodide, a type-3 muscarinic ACh receptor (M3 AChR) inhibitor, abolished ACh-mediated increase in AMPK phosphorylation during H/R. Furthermore, M3 AChR or AMPK siRNA abrogated the ACh-elicited the attenuation of ER stress in endothelial cells, indicating that the salutary effects of ACh were likely mediated by M3 AChR-AMPK signaling. Overall, ACh activated AMPK through M3 AChR, thereby inhibited H/R-induced ER stress and apoptosis in endothelial cells. We have suggested for the first time that AMPK may function as an essential intermediate step between M3 AChR stimulation and inhibition of ER stress-associated apoptotic pathway during H/R, which may help to develop novel therapeutic approaches targeting ER stress to prevent or alleviate ischemia/reperfusion injury. PMID:26066647

  9. Neuroanatomical circuitry mediating the sensory impact of nicotine in the central nervous system.

    PubMed

    Dehkordi, Ozra; Rose, Jed E; Asadi, Sadegh; Manaye, Kebreten F; Millis, Richard M; Jayam-Trouth, Annapurni

    2015-02-01

    Direct actions of nicotine in the CNS appear to be essential for its reinforcing properties. However, activation of nicotinic acetylcholine receptors (nAChRs) on afferent sensory nerve fibers is an important component of addiction to, and withdrawal from, cigarette smoking. The aim of the present study was to identify the neuroanatomical substrates activated by the peripheral actions of nicotine and to determine whether these sites overlap brain structures stimulated by direct actions of nicotine. Mouse brains were examined by immunohistochemistry for c-Fos protein after intraperitoneal injection of either nicotine hydrogen tartrate salt (NIC; 30 and 40 μg/kg) or nicotine pyrrolidine methiodide (NIC-PM; 20 and 30 μg/kg). NIC-PM induced c-Fos immunoreactivity (IR) at multiple brain sites. In the brainstem, c-Fos IR was detected in the locus coeruleus, laterodorsal tegmental nucleus, and pedunculotegmental nucleus. In the midbrain, c-Fos IR was observed in areas overlapping the ventral tegmental area (VTA), which includes the paranigral nucleus, parainterfascicular nucleus, parabrachial pigmental area, and rostral VTA. Other structures of the nicotine brain-reward circuitry activated by NIC-PM included the hypothalamus, paraventricular thalamic nucleus, lateral habenular nucleus, hippocampus, amygdala, accumbens nucleus, piriform cortex, angular insular cortex, anterior olfactory nucleus, lateral septal nucleus, bed nucleus of stria terminalis, cingulate and medial prefrontal cortex, olfactory tubercle, and medial and lateral orbital cortex. NIC, acting through central and peripheral nAChRs, produced c-Fos IR in areas that overlapped NIC-PM-induced c-Fos-expressing sites. These neuroanatomical data are the first to demonstrate that the CNS structures that are the direct targets of nicotine are also anatomical substrates for the peripheral sensory impact of nicotine. PMID:25223294

  10. Mechanism of the cardiovascular effects of the GABAA receptors of the ventral tegmental area of the rat brain.

    PubMed

    Yeganeh, Fahimeh; Ranjbar, Afsaneh; Hatam, Masoumeh; Nasimi, Ali

    2015-07-23

    The ventral tegmental area (VTA) contains GABA terminals involved in the regulation of the cardiovascular system. Previously, we demonstrated that blocking GABAA but not GABAB receptors produced a pressor response accompanied by marked bradycardia. This study was performed to find the possible mechanisms involved in these responses by blocking ganglionic nicotinic receptors, peripheral muscarinic receptors or peripheral V1 vasopressin receptors. Experiments were performed on urethane anesthetized male Wistar rats. Drugs were microinjected unilaterally into the VTA (100 nl). The average changes in mean arterial pressure (MAP) and heart rate (HR) were compared between pre- and post-treatment using paired t-test. Injection of bicuculline methiodide (BMI), a GABAA antagonist, into the VTA caused a significant increase in MAP and a decrease in HR. Administration (i.v.) of the nicotinic receptor blocker, hexamethonium, enhanced the pressor response but abolished the bradycardic response to BMI, which ruled out involvement of the sympathetic nervous system. Blockade of the peripheral muscarinic receptors by homatropine (i.v.) abolished the bradycardic effect of BMI, but had no effect on the pressor response, indicating that bradycardia was produced by the parasympathetic outflow to the heart. Both the pressor and bradycardic responses to BMI were blocked by V1 receptor antagonist (i.v.), indicating that administration of BMI in the VTA disinhibited the release of vasopressin into the circulation. In conclusion, we demonstrated that GABAergic mechanism of the VTA exerts a tonic inhibition on vasopressin release through activation of GABAA receptors. The sympathetic system is not involved in the decrease of blood pressure by GABA of the VTA. PMID:26079327

  11. New insights on amygdala: Basomedial amygdala regulates the physiological response to social novelty.

    PubMed

    Mesquita, Laura Tavares; Abreu, Aline Rezende; de Abreu, Alessandra Rezende; de Souza, Aline Arlindo; de Noronha, Sylvana Rendeiro; Silva, Fernanda Cacilda; Campos, Glenda Siqueira Viggiano; Chianca, Deoclecio Alves; de Menezes, Rodrigo Cunha

    2016-08-25

    The amygdala has been associated with a variety of functions linked to physiological, behavioral and endocrine responses during emotional situations. This brain region is comprised of multiple sub-nuclei. These sub-nuclei belong to the same structure, but may be involved in different functions, thereby making the study of each sub-nuclei important. Yet, the involvement of the basomedial amygdala (BMA) in the regulation of emotional states has yet to be defined. Therefore, the aim of our study was to investigate the regulatory role of the BMA on the responses evoked during a social novelty model and whether the regulatory role depended on an interaction with the dorsomedial hypothalamus (DMH). Our results showed that the chemical inhibition of the BMA by the microinjection of muscimol (γ-aminobutyric acid (GABAA) agonist) promoted increases in mean arterial pressure (MAP) and heart rate (HR), whereas the chemical inhibition of regions near the BMA did not induce such cardiovascular changes. In contrast, the BMA chemical activation by the bilateral microinjection of bicuculline methiodide (BMI; GABAA antagonist), blocked the increases in MAP and HR observed when an intruder rat was suddenly introduced into the cage of a resident rat, and confined to the small cage for 15min. Additionally, the increase in HR and MAP induced by BMA inhibition were eliminated by DMH chemical inhibition. Thus, our data reveal that the BMA is under continuous GABAergic influence, and that its hyperactivation can reduce the physiological response induced by a social novelty condition, possibly by inhibiting DMH neurons. PMID:27261213

  12. Inhibition by levetiracetam of a non-GABAA receptor-associated epileptiform effect of bicuculline in rat hippocampus

    PubMed Central

    Margineanu, Doru Georg; Wülfert, Ernst

    1997-01-01

    Extracellular recording of field potentials, evoked by commissural stimulation in hippocampal area CA3 of anaesthetized rats, was performed in order to study the mode of action of the novel antiepileptic drug levetiracetam (ucb LO59). The amplitude of orthodromic field population spike (PS2) markedly increased and repetitive population spikes appeared when the recording micropipette contained either bicuculline methiodide (BMI), or the specific GABAA antagonist gabazine (SR-95531). BMI-induced increases in PS2 were reduced in a dose-dependent manner by 1 to 320 μmol kg−1 levetiracetam i.v., with a U-shape dose-response relationship. However, levetiracetam did not reduce the increases in PS2 produced by gabazine. Clonazepam (1 mg kg−1, i.p.), carbamazepine (20 mg kg−1, i.p.) and valproate (200 mg kg−1, i.v.) were ineffective in preventing BMI-induced increases in PS2, while the calcium channel antagonist flunarizine, 50 μmol kg−1, i.p., reduced PS2 increments caused by BMI. The L-type calcium channel blocker nifedipine, 100 μmol kg−1, i.p., was without effect. Similar to levetiracetam, flunarizine did not reduce the increases in PS2 induced by gabazine. These data suggest that the increased excitability of CA3 neurones, caused by BMI administered in situ, involves calcium-dependent processes not associated with blockade of GABAA receptors. The inhibition by levetiracetam of this calcium-dependent effect of BMI might contribute to the antiepileptic effects of the drug. PMID:9401779

  13. Acetylcholine ameliorates endoplasmic reticulum stress in endothelial cells after hypoxia/reoxygenation via M3 AChR-AMPK signaling

    PubMed Central

    Bi, Xueyuan; He, Xi; Xu, Man; Zhao, Ming; Yu, Xiaojiang; Lu, Xingzhu; Zang, Weijin

    2015-01-01

    Endoplasmic reticulum (ER) stress is associated with various cardiovascular diseases. However, its pathophysiological relevance and the underlying mechanisms in the context of hypoxia/reoxygenation (H/R) in endothelial cells are not fully understood. Previous findings have suggested that acetylcholine (ACh), the major vagal nerve neurotransmitter, protected against cardiomyocyte injury by activating AMP-activated protein kinase (AMPK). This study investigated the role of ER stress in endothelial cells during H/R and explored the beneficial effects of ACh. Our results showed that H/R triggered ER stress and apoptosis in endothelial cells, evidenced by the elevation of glucose-regulated protein 78, cleaved caspase-12 and C/EBP homologous protein expression. ACh significantly decreased ER stress and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling positive cells and restored ER ultrastructural changes induced by H/R, possibly via protein kinase-like ER kinase and inositol-requiring kinase 1 pathways. Additionally, 4-diphenylacetoxy-N-methylpiperidine methiodide, a type-3 muscarinic ACh receptor (M3 AChR) inhibitor, abolished ACh-mediated increase in AMPK phosphorylation during H/R. Furthermore, M3 AChR or AMPK siRNA abrogated the ACh-elicited the attenuation of ER stress in endothelial cells, indicating that the salutary effects of ACh were likely mediated by M3 AChR-AMPK signaling. Overall, ACh activated AMPK through M3 AChR, thereby inhibited H/R-induced ER stress and apoptosis in endothelial cells. We have suggested for the first time that AMPK may function as an essential intermediate step between M3 AChR stimulation and inhibition of ER stress-associated apoptotic pathway during H/R, which may help to develop novel therapeutic approaches targeting ER stress to prevent or alleviate ischemia/reperfusion injury. PMID:26066647

  14. Agonist activation of cytosolic Ca2+ in subfornical organ cells projecting to the supraoptic nucleus

    NASA Technical Reports Server (NTRS)

    Johnson, R. F.; Beltz, T. G.; Sharma, R. V.; Xu, Z.; Bhatty, R. A.; Johnson, A. K.

    2001-01-01

    The subfornical organ (SFO) is sensitive to both ANG II and ACh, and local application of these agents produces dipsogenic responses and vasopressin release. The present study examined the effects of cholinergic drugs, ANG II, and increased extracellular osmolarity on dissociated, cultured cells of the SFO that were retrogradely labeled from the supraoptic nucleus. The effects were measured as changes in cytosolic calcium in fura 2-loaded cells by using a calcium imaging system. Both ACh and carbachol increased intracellular ionic calcium concentration ([Ca2+]i). However, in contrast to the effects of muscarinic receptor agonists on SFO neurons, manipulation of the extracellular osmolality produced no effects, and application of ANG II produced only moderate effects on [Ca2+]i in a few retrogradely labeled cells. The cholinergic effects on [Ca2+]i could be blocked with the muscarinic receptor antagonist atropine and with the more selective muscarinic receptor antagonists pirenzepine and 4-diphenylacetoxy-N-methylpiperdine methiodide (4-DAMP). In addition, the calcium in the extracellular fluid was required for the cholinergic-induced increase in [Ca2+]i. These findings indicate that ACh acts to induce a functional cellular response in SFO neurons through action on a muscarinic receptor, probably of the M1 subtype and that the increase of [Ca2+]i, at least initially, requires the entry of extracellular Ca2+. Also, consistent with a functional role of M1 receptors in the SFO are the results of immunohistochemical preparations demonstrating M1 muscarinic receptor-like protein present within this forebrain circumventricular organ.

  15. The Sensory Impact of Nicotine on Noradrenergic and Dopaminergic Neurons of the Nicotine Reward - Addiction Neurocircuitry

    PubMed Central

    Rose, Jed E; Dehkordi, Ozra; Manaye, Kebreten F; Millis, Richard M; Cianaki, Salman Ameri; Jayam-Trouth, Annapurni

    2016-01-01

    The sensory experience of smoking is a key component of nicotine addiction known to result, in part, from stimulation of nicotinic acetylcholine receptors (nAChRs) at peripheral sensory nerve endings. Such stimulation of nAChRs is followed by activation of neurons at multiple sites in the mesocorticolimbic reward pathways. However, the neurochemical profiles of CNS cells that mediate the peripheral sensory impact of nicotine remain unknown. In the present study in mice, we first used c-Fos immunohistochemistry to identify CNS cells stimulated by nicotine (NIC, 40 μg/kg, IP) and by a peripherally-acting analog of nicotine, nicotine pyrrolidine methiodide (NIC-PM, 30 μg/kg, IP). Sequential double-labelling was then performed to determine whether noradrenergic and dopaminergic neurons of the nicotine reward-addiction circuitry were primary targets of NIC and NIC-PM. Double-labelling of NIC and/or NIC-PM activated c-Fos immunoreactive cells with tyrosine hydroxylase (TH) showed no apparent c-Fos expression by the dopaminergic cells of the ventral tegmental area (VTA). With the exception of sparse numbers of TH immunoreactive D11 cells, dopamine-containing neurons in other areas of the reward-addiction circuitry, namely periaqueductal gray, and dorsal raphe, were also devoid of c-Fos immunoreactivity. Noradrenergic neurons of locus coeruleus (LC), known to innervate VTA, were activated by both NIC and NIC-PM. These results demonstrate that noradrenergic neurons of LC are among the first structures that are stimulated by single acute IP injection of NIC and NIC-PM. Dopaminergic neurons of VTA and other CNS sites, did not respond to acute IP administration of NIC or NIC-PM by induction of c-Fos. PMID:27347434

  16. Rational Basis for the Use of Bergamot Essential Oil in Complementary Medicine to Treat Chronic Pain.

    PubMed

    Rombolà, L; Amantea, D; Russo, R; Adornetto, A; Berliocchi, L; Tridico, L; Corasaniti, M T; Sakurada, S; Sakurada, T; Bagetta, G; Morrone, L A

    2016-01-01

    In complementary medicine, aromatherapy uses essential oils to improve agitation and aggression observed in dementia, mood, depression, anxiety and chronic pain. Preclinical research studies have reported that the essential oil obtained from bergamot (BEO) fruit (Citrus bergamia, Risso) modifies normal and pathological synaptic plasticity implicated, for instance, in nociceptive and neuropathic pain. Interestingly, recent results indicated that BEO modulates sensitive perception of pain in different models of nociceptive, inflammatory and neuropathic pain modulating endogenous systems. Thus, local administration of BEO inhibited the nociceptive behavioral effect induced by intraplantar injection of capsaicin or formalin in mice. Similar effects were observed with linalool and linalyl acetate, major volatile components of the phytocomplex, Pharmacological studies showed that the latter effects are reversed by local or systemic pretreatment with the opioid antagonist naloxone hydrochloride alike with naloxone methiodide, high affinity peripheral μ-opioid receptor antagonist. These results and the synergistic effect observed following systemic or intrathecal injection of an inactive dose of morphine with BEO or linalool indicated an activation of peripheral opioid system. Recently, in neuropathic pain models systemic or local administration of BEO or linalool induced antiallodynic effects. In particular, in partial sciatic nerve ligation (PSNL) model, intraplantar injection of the phytocomplex or linalool in the ipsilateral hindpaw, but not in the contralateral, reduced PSNL-induced extracellularsignal- regulated kinase (ERK) activation and mechanical allodynia. In neuropathic pain high doses of morphine are needed to reduce pain. Interestingly, combination of inactive doses of BEO or linalool with a low dose of morphine induced antiallodynic effects in mice. Peripheral cannabinoid and opioid systems appear to be involved in the antinociception produced by

  17. Thermodynamics of antagonist binding to rat muscarinic M2 receptors: antimuscarinics of the pridinol, sila-pridinol, diphenidol and sila-diphenidol type.

    PubMed Central

    Waelbroeck, M.; Camus, J.; Tastenoy, M.; Lambrecht, G.; Mutschler, E.; Kropfgans, M.; Sperlich, J.; Wiesenberger, F.; Tacke, R.; Christophe, J.

    1993-01-01

    1. We studied the effect of temperature on the binding to rat heart M2 muscarinic receptors of antagonists related to the carbon/silicon pairs pridinol/sila-pridinol and diphenidol/sila-diphenidol (including three germanium compounds) and six structurally related pairs of enantiomers [(R)- and (S)-procyclidine, (R)- and (S)-trihexyphenidyl, (R)- and (S)-tricyclamol, (R)- and (S)-trihexyphenidyl methiodide, (R)- and (S)-hexahydro-diphenidol and (R)- and (S)-hexbutinol]. Binding affinities were determined in competition experiments using [3H]-N-methyl-scopolamine chloride as radioligand. The reference drugs were scopolamine and N-methyl-scopolamine bromide. 2. The affinity of the antagonists either increased or decreased with temperature. van't Hoff plots were linear in the 278-310 degrees K temperature range. Binding of all antagonists was entropy driven. Enthalpy changes varied from large negative values (down to -29 kJ mol-1) to large positive values (up to +30 kJ mol-1). 3. (R)-configurated drugs had a 10 to 100 fold greater affinity for M2 receptors than the corresponding (S)-enantiomers. Enthalpy and entropy changes of the respective enantiomers were different but no consistent pattern was observed. 4. When silanols (R3SiOH) were compared to carbinols (R3COH), the affinity increase caused by C/Si exchange varied between 3 and 10 fold for achiral drugs but was negligible in the case of chiral drugs. Silanols induced more favourable enthalpy and less favourable entropy changes than the corresponding carbinols when binding. Organogermanium compounds (R4Ge) when compared to their silicon counterparts (R4Si) showed no significant difference in affinity as well as in enthalpy and entropy changes. 5. Exchange of a cyclohexyl by a phenyl moiety was associated with an increase or a decrease in drug affinity (depending on the absolute configuration in the case of chiral drugs) and generally also with a more favourable enthalpy change and a less favourable entropy change

  18. Early Systemic Granulocyte-Colony Stimulating Factor Treatment Attenuates Neuropathic Pain after Peripheral Nerve Injury

    PubMed Central

    Lee, Yun-Lin; Chen, Jin-Chung; Wang, Hung-Li; Yang, Yi-Ling; Cheng, Mei-Yun; Liao, Ming-Feng; Ro, Long-Sun

    2012-01-01

    Recent studies have shown that opioid treatment can reduce pro-inflammatory cytokine production and counteract various neuropathic pain syndromes. Granulocyte colony-stimulating factor (G-CSF) can promote immune cell differentiation by increasing leukocytes (mainly opioid-containing polymorphonuclear (PMN) cells), suggesting a potential beneficial role in treating chronic pain. This study shows the effectiveness of exogenous G-CSF treatment (200 µg/kg) for alleviating thermal hyperalgesia and mechanical allodynia in rats with chronic constriction injury (CCI), during post-operative days 1–25, compared to that of vehicle treatment. G-CSF also increases the recruitment of opioid-containing PMN cells into the injured nerve. After CCI, single administration of G-CSF on days 0, 1, and 2, but not on day 3, relieved thermal hyperalgesia, which indicated that its effect on neuropathic pain had a therapeutic window of 0–48 h after nerve injury. CCI led to an increase in the levels of interleukin-6 (IL-6) mRNA and tumor necrosis factor-α (TNF-α) protein in the dorsal root ganglia (DRG). These high levels of IL-6 mRNA and TNF-α were suppressed by a single administration of G-CSF 48–144 h and 72–144 h after CCI, respectively. Furthermore, G-CSF administered 72–144 h after CCI suppressed the CCI-induced upregulation of microglial activation in the ipsilateral spinal dorsal horn, which is essential for sensing neuropathic pain. Moreover, the opioid receptor antagonist naloxone methiodide (NLXM) reversed G-CSF-induced antinociception 3 days after CCI, suggesting that G-CSF alleviates hyperalgesia via opioid/opioid receptor interactions. These results suggest that an early single systemic injection of G-CSF alleviates neuropathic pain via activation of PMN cell-derived endogenous opioid secretion to activate opioid receptors in the injured nerve, downregulate IL-6 and TNF-α inflammatory cytokines, and attenuate microglial activation in the spinal dorsal horn. This

  19. A select set of opioid ligands induce up-regulation by promoting the maturation and stability of the rat kappa-opioid receptor in human embryonic kidney 293 cells.

    PubMed

    Wannemacher, Kenneth M; Yadav, Prem N; Howells, Richard D

    2007-11-01

    Ligand-induced regulation of the rat kappa-opioid receptor (rKOR) was investigated in human embryonic kidney 293 cells stably expressing the FLAG-tagged rKOR. Incubation of rKOR cells with naltrexone for 24 h increased the B(max) >3-fold, with no change in the affinity of [(3)H]diprenorphine. Two immunoreactive receptor species were present in cell lysates: naltrexone treatment caused a >3-fold increase in the 52-kDa species while decreasing the level of the 42-kDa species. Dynorphin(1-13), U69,593 [(5alpha,7alpha,8beta)-(+)-N-methyl-N-(7-[1-pyrrolidinyl]-1-oxaspiro[4,5]dec-8-yl)benzeneacetamide], or salvinorin A [2S,4aR,6aR,7R,9S,10aS, 10bR)-9-(acetyloxy)-2-(3-furanyl)dodecahydro-6a,10b-dimethyl-4,10-dioxo-2H-naphtho[2,1c]pyran-7-carboxylic acid methyl ester] treatment did not alter the level of immunoreactive rKOR protein, whereas etorphine, cyclazocine, naloxone, and naloxone methiodide increased the 52-kDa and decreased the 42-kDa rKOR bands. Receptor up-regulation was associated with an increase in the number of cell surface receptors and a 2-fold increase in the E(max) for guanosine 5'-O-(3-[(35)S]thio)triphosphate binding. Glycosidase digestion indicated that the 52- and 42-kDa receptors contained complex and high-mannose N-glycans, respectively, Pulse-chase analysis and glycosidase digestion sensitivities suggested that the 42-kDa rKOR species was a precursor of the 52-kDa species. Naltrexone did not alter rKOR mRNA levels or translational efficiency, and rKOR up-regulation was not inhibited by cycloheximide. Brefeldin A caused accumulation of intracellular rKOR intermediates, and coincubation with naltrexone increased the levels of the brefeldin-induced species significantly. These results suggest that select opioid ligands up-regulate rKOR by enhancing the rate of receptor folding and maturation and by protecting the receptor from degradation, resulting in an increase in the number of rKOR binding sites, immunoreactive protein, and functional receptors

  20. Site-selective chemical modification of chymotrypsin using peptidyl derivatives bearing optically active diphenyl 1-amino-2-phenylethylphosphonate: Stereochemical effect of the diphenyl phosphonate moiety.

    PubMed

    Ono, Shin; Nakai, Takahiko; Kuroda, Hirofumi; Miyatake, Ryuta; Horino, Yoshikazu; Abe, Hitoshi; Umezaki, Masahito; Oyama, Hiroshi

    2016-11-01

    Diphenyl (α-aminoalkyl)phosphonates act as mechanism-based inhibitors against serine proteases by forming a covalent bond with the hydroxy group of the active center Ser residue. Because the covalent bond was found to be broken and replaced by 2-pyridinaldoxime methiodide (2PAM), we employed a peptidyl derivative bearing diphenyl 1-amino-2-phenylethylphosphonate moiety (Phe(p) (OPh)2 ) to target the active site of chymotrypsin and to selectively anchor to Lys175 in the vicinity of the active site. Previously, it was reported that the configuration of the α-carbon of phosphorus in diphenyl (α-aminoalkyl)phosphonates affects the inactivation reaction of serine proteases, i.e., the (R)-enantiomeric diphenyl phosphonate is comparable to l-amino acids and it effectively reacts with serine proteases, whereas the (S)-enantiomeric form does not. In this study, we evaluated the stereochemical effect of the phosphonate moiety on the selective chemical modification. Epimeric dipeptidyl derivatives, Ala-(R or S)-Phe(p) (OPh)2 , were prepared by separation with RP-HPLC. A tripeptidyl (R)-epimer (Ala-Ala-(R)-Phe(p) (OPh)2 ) exhibited a more potent inactivation ability against chymotrypsin than the (S)-epimer. The enzyme inactivated by the (R)-epimer was more effectively reactivated with 2PAM than the enzyme inactivated by the (S)-epimer. Finally, N-succinimidyl (NHS) active ester derivatives, NHS-Suc-Ala-Ala- (R or S)-Phe(p) (OPh)2 , were prepared, and we evaluated their action when modifying Lys175 in chymotrypsin. We demonstrated that the epimeric NHS derivative that possessed the diphenyl phosphonate moiety with the (R)-configuration effectively modified Lys175 in chymotrypsin, whereas that with the (S)-configuration did not. These results demonstrate the utility of peptidyl derivatives that bear an optically active diphenyl phosphonate moiety as affinity labeling probes in protein bioconjugation. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 521-530, 2016

  1. Mechanisms underlying activation of transient BK current in rabbit urethral smooth muscle cells and its modulation by IP3-generating agonists

    PubMed Central

    Kyle, Barry D.; Bradley, Eamonn; Large, Roddy; Sergeant, Gerard P.; McHale, Noel G.; Thornbury, Keith D.

    2013-01-01

    We used the perforated patch-clamp technique at 37°C to investigate the mechanisms underlying the activation of a transient large-conductance K+ (tBK) current in rabbit urethral smooth muscle cells. The tBK current required an elevation of intracellular Ca2+, resulting from ryanodine receptor (RyR) activation via Ca2+-induced Ca2+ release, triggered by Ca2+ influx through L-type Ca2+ (CaV) channels. Carbachol inhibited tBK current by reducing Ca2+ influx and Ca2+ release and altered the shape of spike complexes recorded under current-clamp conditions. The tBK currents were blocked by iberiotoxin and penitrem A (300 and 100 nM, respectively) and were also inhibited when external Ca2+ was removed or the CaV channel inhibitors nifedipine (10 μM) and Cd2+ (100 μM) were applied. The tBK current was inhibited by caffeine (10 mM), ryanodine (30 μM), and tetracaine (100 μM), suggesting that RyR-mediated Ca2+ release contributed to the activation of the tBK current. When IP3 receptors (IP3Rs) were blocked with 2-aminoethoxydiphenyl borate (2-APB, 100 μM), the amplitude of the tBK current was not reduced. However, when Ca2+ release via IP3Rs was evoked with phenylephrine (1 μM) or carbachol (1 μM), the tBK current was inhibited. The effect of carbachol was abolished when IP3Rs were blocked with 2-APB or by inhibition of muscarinic receptors with the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (1 μM). Under current-clamp conditions, bursts of action potentials could be evoked with depolarizing current injection. Carbachol reduced the number and amplitude of spikes in each burst, and these effects were reduced in the presence of 2-APB. In the presence of ryanodine, the number and amplitude of spikes were also reduced, and carbachol was without further effect. These data suggest that IP3-generating agonists can modulate the electrical activity of rabbit urethral smooth muscle cells and may contribute to the effects of neurotransmitters on

  2. Rhythm generation in organotypic medullary cultures of newborn rats.

    PubMed

    Baker, R E; Ballantyne, D; Bingmann, D; Jones, D; Widman, G

    1995-12-01

    Organotypic transverse medullary slices (obex level) from six-day-old rats, cultured for two to four weeks in chemically defined medium contained rhythmically discharging neurones which were activated by CO2 and H+. The mechanisms underlying this rhythmicity and the spread of excitation and synaptic transmission within this organotypic tissue were examined by modifying the composition of the external solution. Our findings showed that (1) Exposure to tetrodotoxin (0.2 microM) or to high magnesium (6 mM) and low calcium (0.2 mM) concentrations abolished periodic activity. (2) Neither the blockade of GABAergic potentials with bicuculline methiodide (200 microM) and/or hydroxysaclofen (200 microM) nor the blockade of glycinergic potentials with strychnine hydrochloride (100 microM) abolished rhythmicity. (3) While atropine sulphate (5 microM) was ineffective in modulating periodic discharges nicotine (100 microM) - like CO2-shortened the intervals between the periodic events; hexamethonium (50-100 microM) reduced both periodic and aperiodic activity. (4) Exposure to the NMDA antagonist 2-aminophosphonovaleric acid (50 microM) suppressed periodic events only transiently. In the presence of 2-aminophosphonovaleric acid rhythmicity recovered. However, the AMPA-antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (10-50 microM), abolished periodic activity reversibly within less than 5 min. When 6-cyano-7-nitroquinoxaline-2,3-dione and nicotine were administered simultaneously periodic events persisted for up to 10 min. These findings indicate that synaptic excitatory drive is a prerequisite for the generation of rhythmic discharges of medullary neurones in this preparation. This drive may activate voltage-dependent channels or it may facilitate endogenous cellular mechanisms which initiate oscillations of intracellular calcium concentration. To test the latter possibility (5) calcium antagonists were added to the bath saline. The organic calcium antagonists verapamil and

  3. Ligand binding and functional characterization of muscarinic acetylcholine receptors on the TE671/RD human cell line

    SciTech Connect

    Bencherif, M.; Lukas, R.J. )

    1991-06-01

    Cells of the TE671/RD human clonal line express a finite number ((Bmax) of about 350 fmol/mg of membrane protein) of apparently noninteracting, high-affinity binding sites (KD of 0.07 nM and a Hill coefficient close to unity, nH = 0.94) for the muscarinic acetylcholine receptor (mAChR) radio antagonist, tritium-labeled quinuclidinyl benzilate ({sup 3}H-QNB). The rank order potency of selective antagonists that inhibit specific {sup 3}HQNB binding is: atropine greater than 4-DAMP (4-diphenylacetoxy-N-methylpiperidine methiodide) greater than pirenzepine greater than methoctramine greater than AFDx-116 (11-2(2-((diethylamino)methyl)-1-(piperidinyl) acetyl)-5,11-dihydro-6H-pyrido(2,3-b)(1,4)benzodiazepin-6-one). Functional studies indicate that phosphoinositide (PIns) hydrolysis in TE671/RD cells is increased by carbachol (EC50 of 10 microM), but not by nicotine (to concentrations as high as 1 mM). Agonist-stimulated PIns metabolism is inhibited by antagonists with the same rank order potency as for inhibition of {sup 3}HQNB binding. Functional responses are augmented in the presence of a nonhydrolyzable GTP analog, are strongly inhibited after 24-hr exposure to cholera toxin, but are only slightly inhibited after long-term exposure to pertussis toxin or forskolin. These studies identify a pharmacologically-defined M3-subtype of mAChR strongly coupled via a cholera toxin-sensitive mechanism to PIns hydrolysis in these cells. Within 1 hr of treatment of TE671/RD cells with 1 mM dibutyryl cyclic AMP or with 10 microM phorbol-12-myristate-13-acetate (PMA), there is a 30 to 50% decrease in carbachol-stimulated PIns responsiveness that recovers to control values after 5 days of continued drug treatment. However, a comparable and more persistent inhibition of mAChR function is observed on cell treatment with 20 nM PMA.

  4. Intrinsic and Network Mechanisms Constrain Neural Synchrony in the Moth Antennal Lobe

    PubMed Central

    Lei, Hong; Yu, Yanxue; Zhu, Shuifang; Rangan, Aaditya V.

    2016-01-01

    Projection-neurons (PNs) within the antennal lobe (AL) of the hawkmoth respond vigorously to odor stimulation, with each vigorous response followed by a ~1 s period of suppression—dubbed the “afterhyperpolarization-phase,” or AHP-phase. Prior evidence indicates that this AHP-phase is important for the processing of odors, but the mechanisms underlying this phase and its function remain unknown. We investigate this issue. Beginning with several physiological experiments, we find that pharmacological manipulation of the AL yields surprising results. Specifically, (a) the application of picrotoxin (PTX) lengthens the AHP-phase and reduces PN activity, whereas (b) the application of Bicuculline-methiodide (BIC) reduces the AHP-phase and increases PN activity. These results are curious, as both PTX and BIC are inhibitory-receptor antagonists. To resolve this conundrum, we speculate that perhaps (a) PTX reduces PN activity through a disinhibitory circuit involving a heterogeneous population of local-neurons, and (b) BIC acts to hamper certain intrinsic currents within the PNs that contribute to the AHP-phase. To probe these hypotheses further we build a computational model of the AL and benchmark our model against our experimental observations. We find that, for parameters which satisfy these benchmarks, our model exhibits a particular kind of synchronous activity: namely, “multiple-firing-events” (MFEs). These MFEs are causally-linked sequences of spikes which emerge stochastically, and turn out to have important dynamical consequences for all the experimentally observed phenomena we used as benchmarks. Taking a step back, we extract a few predictions from our computational model pertaining to the real AL: Some predictions deal with the MFEs we expect to see in the real AL, whereas other predictions involve the runaway synchronization that we expect when BIC-application hampers the AHP-phase. By examining the literature we see support for the former, and we

  5. Pharmacological comparison of the cloned human and rat M2 muscarinic receptor genes expressed in the murine fibroblast (B82) cell line.

    PubMed

    Kovacs, I; Yamamura, H I; Waite, S L; Varga, E V; Roeske, W R

    1998-02-01

    The coding sequence of the human m2 receptor gene was amplified by polymerase chain reaction and stably transfected into a murine fibroblast cell line (B82). We have compared the human M2 clonal cell line (HM2-B10) with the previously established B82 cell line (M2LKB2-2) expressing the rat M2 receptor to assess drug specificity, drug selectivity and effector coupling. Both transfected cell lines showed a high level of specific, saturable [3H](-)-N-methyl-3-quinuclidinyl benzilate binding with Kd values of 243 pM (155-352 pM) and 345 pM (234-539 pM) and Bmax values of 97 +/- 4 and 338 +/- 16 fmol/10(6) cells, respectively. Inhibition of [3H](-)-N-methyl-3-quinuclidinyl benzilate binding to HM2-B10 cells and M2LKB2-2 cells showed the same rank order of potency for the antagonists: atropine > dexetimide > 4-diphenylacetoxy-N-methylpiperidine methiodide > himbacine > methoctramine > 11-[[2-[(diethylamino) methyl]-1-piperidinyl]acetyl]-5,11-dihidro-6H-pyrido-[2,3-b](1, 4)-benzodiazepine-6-one > hexahydro-sila-difenidol hydro-chloride > pirenzepine. Correlation analysis of the pKi values indicate that the expressed human and rat M2 receptors have nearly identical ligand-binding characteristics. Carbachol inhibited forskolin-stimulated cAMP formation with similar potency in both cell lines [EC50 = 2.4 microM (0.2-2.8) and 1.1 microM (0.2-5.3) for the human and rat M2 receptor, respectively]. In the M2LKB2-2 cells, carbachol slightly stimulated the [3H]inositol monophosphate formation but had no significant effect in HM2-B10 cells. In conclusion, the human and rat M2 receptors expressed in the B82 cell line have very similar binding properties but exhibit slight differences in effector coupling mechanisms. PMID:9454790

  6. Blunted endogenous GABA-mediated inhibition in the hypothalamic paraventricular nucleus of rats with streptozotocin-induced diabetes.

    PubMed

    Hassan, Zurina; Sattar, Munavvar Zubaid Abdul; Suhaimi, Farah Wahida; Yusoff, Nurul Hasnida Mohammed; Abdulla, Mohammed H; Yusof, Ahmad Pauzi M; Johns, Edward J

    2013-09-01

    The hypothalamic paraventricular nucleus (PVN) is involved in the regulation of sympathetic outflow and particularly affects the heart. This study sets out to determine the role of GABA of the paraventricular nucleus (PVN) in cardiovascular regulation in streptozotocin-induced diabetic rats. Pharmacological stimulation of glutamatergic receptors with DL-Homocysteic acid (200 mM in 100 nL) in the PVN region showed a significant depression in both mean arterial pressure (MAP) and heart rate (HR) of diabetic rats (Diabetic vs. non-diabetic: MAP 15.0 ± 1.5 vs. 35.8 ± 2.8 mmHg; HR 3.0 ± 2.0 vs. 30.0 ± 6.0 bpm, P < 0.05). Microinjection of bicuculline methiodide (1 mM in 100 nL), a GABAA receptor antagonist, produced an increase in baseline MAP and HR in both non-diabetic and diabetic rats. In the diabetic rats, bicuculline injection into the PVN reduced the pressor and HR responses (Diabetic vs. non-diabetic: MAP 6.2 ± 0.8 vs. 25.1 ± 2.2 mmHg; HR 1.8 ± 1.1 vs. 25.4 ± 6.2 bpm, P < 0.05). A microinjection of muscimol (2 mM in 100 nL), which is a GABAA receptor agonist, in the PVN elicited decreases in MAP and HR in both groups. The diabetic group showed a significantly blunted reduction in HR, but not MAP (Diabetic vs. non-diabetic: MAP -15.7 ± 4.0 vs. -25.0 ± 3.8 mmHg; HR -5.2 ± 2.1 vs. -39.1 ± 7.9 bpm). The blunted vasopressor and tachycardic responses to bicuculline microinjection in the diabetic rats are likely to result from decreased GABAergic inputs, attenuated release of endogenous GABA or alterations in GABAA receptors within the PVN. PMID:23242937

  7. Cocaine action on peripheral, non-monoamine neural substrates as a trigger of electroencephalographic desynchronization and electromyographic activation following i.v. administration in freely moving rats.

    PubMed

    Smirnov, M S; Kiyatkin, E A

    2010-01-20

    Many important physiological, behavioral and subjective effects of i.v. cocaine (COC) are exceptionally rapid and transient, suggesting a possible involvement of peripheral neural substrates in their triggering. In the present study, we used high-speed electroencephalographic (EEG) and electromyographic (EMG) recordings (4-s resolution) in freely moving rats to characterize the central electrophysiological effects of i.v. COC at low doses within a self-administration range (0.25-1.0 mg/kg). We found that COC induces rapid, strong, and prolonged desynchronization of cortical EEG (decrease in alpha and increase in beta and gamma activity) and activation of the neck EMG that begin within 2-6 s following the start of a 10-s injection; immediate components of both effects were dose-independent. The rapid effects of COC were mimicked by i.v. COC methiodide (COC-MET), a derivative that cannot cross the blood-brain barrier. At equimolar doses (0.33-1.33 mg/kg), COC-MET had equally fast and strong effects on EEG and EMG total powers, decreasing alpha and increasing beta and gamma activities. Rapid EEG desynchronization and EMG activation was also induced by i.v. procaine, a structurally similar, short-acting local anesthetic with virtually no effects on monoamine uptake; at equipotential doses (1.25-5.0 mg/kg), these effects were weaker and shorter in duration than those of COC. Surprisingly, i.v. saline injection delivered during slow-wave sleep (but not during quiet wakefulness) also induced a transient EEG desynchronization but without changes in EMG and motor activity; these effects were significantly weaker and much shorter than those induced by all tested drugs. These data suggest that in awake animals, i.v. COC induces rapid cortical activation and a subsequent motor response via its action on peripheral non-monoamine neural elements, involving neural transmission via visceral sensory pathways. By providing a rapid neural signal and triggering neural activation, such

  8. Intravenous Cocaine Induces Rapid, Transient Excitation of Striatal Neurons via its Action on Peripheral Neural Elements: Single-cell, Iontophoretic Study in Awake and Anesthetized Rats

    PubMed Central

    Kiyatkin, Eugene A.; Brown, Paul Leon

    2007-01-01

    Cocaine’s (COC) direct interaction with the dopamine (DA) transporter is usually considered the most important action underlying the psychomotor stimulant and reinforcing effects of this drug. However, some physiological, behavioral and psycho-emotional effects of COC are very rapid and brief and they remain intact during DA receptor blockade, suggesting possible involvement of peripheral non-DA neural mechanisms. To assess this issue, single-unit recording with microiontophoresis was used to examine changes in impulse activity of dorsal and ventral striatal neurons to intravenous (iv) COC (0.25–0.5 mg/kg) in the same rats under two conditions: awake with dopamine (DA) receptor blockade and anesthetized with urethane. In the awake preparation ~70% striatal neurons showed rapid and transient (latency ~ 6 s, duration ~15 s) COC-induced excitations. These effects were stronger in ventral than dorsal striatum. During anesthesia, these phasic effects were fully blocked and COC slowly decreased neuronal discharge rate. COC-methiodide (COC-M), a derivative that cannot cross the blood-brain barrier, also caused phasic excitations in the awake, but not anesthetized condition. In contrast to regular COC, COC-M had no tonic effect on discharge rate in either preparation. Most striatal neurons that were phasically excited by both COC forms also showed short-latency excitations during tail-touch and tail-pinch in the awake preparation, an effect strongly attenuated during anesthesia. Finally, most striatal neurons that in awake conditions were phasically excited by somato-sensory stimuli and COC salts were also excited by iontophoretic glutamate (GLU). Although striatal neurons were sensitive to GLU in both preparations, the response magnitude at the same GLU current was higher in awake than anesthetized conditions. These data suggest that in awake animals iv COC, like somato-sensory stimuli, transiently excites striatal neurons via its action on peripheral neural elements

  9. Differential Effects of the Gβ5-RGS7 Complex on Muscarinic M3 Receptor–Induced Ca2+ Influx and Release

    PubMed Central

    Karpinsky-Semper, Darla; Volmar, Claude-Henry; Brothers, Shaun P.

    2014-01-01

    The G protein β subunit Gβ5 uniquely forms heterodimers with R7 family regulators of G protein signaling (RGS) proteins (RGS6, RGS7, RGS9, and RGS11) instead of Gγ. Although the Gβ5-RGS7 complex attenuates Ca2+ signaling mediated by the muscarinic M3 receptor (M3R), the route of Ca2+ entry (i.e., release from intracellular stores and/or influx across the plasma membrane) is unknown. Here, we show that, in addition to suppressing carbachol-stimulated Ca2+ release, Gβ5-RGS7 enhanced Ca2+ influx. This novel effect of Gβ5-RGS7 was blocked by nifedipine and 2-aminoethoxydiphenyl borate. Experiments with pertussis toxin, an RGS domain–deficient mutant of RGS7, and UBO-QIC {L-threonine,(3R)-N-acetyl-3-hydroxy-L-leucyl-(aR)-a-hydroxybenzenepropanoyl-2,3-idehydro-N-methylalanyl-L-alanyl-N-methyl-L-alanyl-(3R)-3-[[(2S,3R)-3-hydroxy-4- methyl-1-oxo-2-[(1-oxopropyl)amino]pentyl]oxy]-L-leucyl-N,O-dimethyl-,(7→1)-lactone (9CI)}, a novel inhibitor of Gq, showed that Gβ5-RGS7 modulated a Gq-mediated pathway. These studies indicate that Gβ5-RGS7, independent of RGS7 GTPase-accelerating protein activity, couples M3R to a nifedipine-sensitive Ca2+ channel. We also compared the action of Gβ5-RGS7 on M3R-induced Ca2+ influx and release elicited by different muscarinic agonists. Responses to Oxo-M [oxotremorine methiodide N,N,N,-trimethyl-4-(2-oxo-1-pyrrolidinyl)-2-butyn-1-ammonium iodide] were insensitive to Gβ5-RGS7. Pilocarpine responses consisted of a large release and modest influx components, of which the former was strongly inhibited whereas the latter was insensitive to Gβ5-RGS7. McN-A-343 [(4-hydroxy-2-butynyl)-1-trimethylammonium-3-chlorocarbanilate chloride] was the only compound whose total Ca2+ response was enhanced by Gβ5-RGS7, attributed to, in part, by the relatively small Ca2+ release this partial agonist stimulated. Together, these results show that distinct agonists not only have differential M3R functional selectivity, but also confer specific

  10. Down-regulation of muscarinic receptors and the m3 subtype in white-footed mice by dietary exposure to parathion

    USGS Publications Warehouse

    Jett, D.A.; Hill, E.F.; Fernando, J.C.; Eldefrawi, M.E.; Eldefrawi, A.T.

    1993-01-01

    The effect of ad libitum dietary exposure (as occurs in the field) to parathion for 14 d was investigated on the muscarinic acetylcholine receptor (mAChR) in brains and submaxillary glands of adults of a field species, the white-footed mouse Peromyscus leucopus. Immunoprecipitation using subtype selective antibodies revealed that the relative ratios of the m1-m5 mAChR subtypes in Peromyscus brain were similar to those in rat brain. There was little variability in acetylcholinesterase (AChE) activity in control mice brains but large variability in 39 exposed mice, resulting from differences in food ingestion and parathion metabolism. Accordingly, data on radioligand binding to mAChRs in each mouse brain were correlated with brain AChE activity in the same mouse, and AChE inhibition served as a biomarker of exposure reflecting in situ paraoxon concentrations. Exposure to parathion for 14 d reduced maximal binding (Bmax) of [3H]quinuclidinyl benzilate ([3H]QNB), [3H]-N-methylscopolamine ([3H]NMS), and [3H]-4-diphenylacetoxy-N-methylpiperidine methiodide ([3H]-4-DAMP) by up to approximately 58% without affecting receptor affinities for these ligands. Maximal reduction in Bmax of [3H]QNB and [3H]-4-DAMP binding occurred in mice with highest AChE inhibition, while equivalent maximal reduction in Bmax of [3H]NMS occurred in mice with only approximately 10% AChE inhibition, without further change at higher parathion doses. This is believed to be due to the hydrophilicity of [3H]NMS, which limits its accessibility to internalized desensitized receptors. In submaxillary glands (mAChRs are predominantly m3 subtype), there were significant dose-dependent reductions in [3H]QNB binding and m3 mRNA levels in exposed mice, revealed by Northern blot analyses. The reduction in m3 receptors is suggested to result mostly from reduced synthesis at the transcription level, rather than from translational or posttranslational events. The data suggest that down-regulation of mAChRs occurs

  11. Characterization of muscarinic receptors mediating contractions of circular and longitudinal muscle of human isolated colon.

    PubMed Central

    Kerr, P. M.; Hillier, K.; Wallis, R. M.; Garland, C. J.

    1995-01-01

    1. The effects of seven muscarinic receptor antagonists were used to characterize the receptors which mediate carbachol-evoked contractions of intertaenial circular and taenial longitudinal muscle in human isolated colon. The effects of these antagonists were studied upon colon contractions induced by cumulatively added carbachol which had mean EC50 values of 11.7 +/- 2.3 microM (n = 8) and 12.6 +/- 2.3 microM (n = 8) respectively upon circular and longitudinal smooth muscle. 2. All antagonists displaced concentration-response curves to carbachol to the right in a parallel manner. The maximum concentration of each antagonist added (30 nM-10 microM) did not significantly suppress the maximum response. 3. In circular muscle, the M3 muscarinic receptor antagonists, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), hexahydrosiladiphenidol (HHSiD) and para-fluoro-hexahydrosiladiphenidol (p-F-HHSiD) inhibited responses with pA2 values of 9.41 +/- 0.23, 7.17 +/- 0.07, 6.94 +/- 0.18 respectively. The M2 muscarinic receptor antagonist, AF-DX 116, the M2/M4 muscarinic receptor antagonist, himbacine, and the M1 muscarinic receptor antagonist, pirenzepine, yielded pA2 values of 7.36 +/- 0.43, 7.47 +/- 0.14 and 7.23 +/- 0.48 respectively. The non-selective antagonist, atropine, had a pA2 of 8.72 +/- 0.28. 4. In longitudinal muscle 4-DAMP, HHSiD, p-F-HHSiD, AF-DX 116, himbacine and pirenzepine gave pA2 values of 9.09 +/- 0.16, 7.45 +/- 0.43, 7.44 +/- 0.21, 6.44 +/- 0.1, 7.54 +/- 0.40, 6.87 +/- 0.38 respectively. Atropine yielded a pA2 value of 8.60 +/- 0.08.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8564213

  12. Spatiotemporal dynamics of excitation in rat insular cortex: intrinsic corticocortical circuit regulates caudal-rostro excitatory propagation from the insular to frontal cortex.

    PubMed

    Fujita, S; Adachi, K; Koshikawa, N; Kobayashi, M

    2010-01-13

    The insular cortex (IC), composing unique anatomical connections, receives multi-modal sensory inputs including visceral, gustatory and somatosensory information from sensory thalamic nuclei. Axonal projections from the limbic structures, which have a profound influence on induction of epileptic activity, also converge onto the IC. However, functional connectivity underlying the physiological and pathological roles characteristic to the IC still remains unclear. The present study sought to elucidate the spatiotemporal dynamics of excitatory propagation and their cellular mechanisms in the IC using optical recording in urethane-anesthetized rats. Repetitive electrical stimulations of the IC at 50 Hz demonstrated characteristic patterns of excitatory propagation depending on the stimulation sites. Stimulation of the granular zone of the IC (GI) and other surrounding cortices such as the motor/primary sensory/secondary sensory cortices evoked round-shaped excitatory propagations, which often extended over the borders of adjacent areas, whereas excitation of the agranular and dysgranular zones in the IC (AI and DI, respectively) spread along the rostrocaudal axis parallel to the rhinal fissure. Stimulation of AI/DI often evoked excitation in the dorsolateral orbital cortex, which exhibited spatially discontinuous topography of excitatory propagation in the IC. Pharmacological manipulations using 6,7-dinitroquinoxaline-2,3(1H,4H)-dione (DNQX), a non-NMDA receptor antagonist, D-2-amino-5-phosphonovaleric acid (D-APV), an NMDA receptor antagonist, and bicuculline methiodide, a GABA(A) receptor antagonist, indicate that excitatory propagation was primarily regulated by non-NMDA and GABA(A) receptors. Microinjection of lidocaine or incision of the supragranular layers of the rostrocaudally middle part of excitatory regions suppressed excitation in the remote regions from the stimulation site, suggesting that the excitatory propagation in the IC is largely mediated by

  13. Thermodynamic and kinetic control of charged, amphiphilic triblock copolymer assembly via interaction with organic counterions in solvent mixtures

    NASA Astrophysics Data System (ADS)

    Cui, Honggang

    2007-12-01

    assembly process include THF/water ratio, PS block length, the type and amount of organic counterions, and the mixing pathway. Their formation mechanism has been investigated from three aspects: (i) the chain structure of organic counterions, including spacer length, chain hydrophobicity between ionizable groups and the number of ionizable groups (amine group); (ii) molecular structure of the triblock copolymer, including block length of polystyrene and chain architecture; (iii) relative variation of the components, such as different ratios of THF to water and the different ratios of amine groups to acid groups. The first example of a novel micelle formed was the toroidal micelle. The toroidal micelle morphology, which is theoretically predicted but rarely observed, has been produced by the self assembly of PAA99- b-PMA73-b-PS66 in combination with 2,2-(ethylenedioxy)diethylamine (EDDA) and mixed THF/H2O solvent. It was found that toroids can be constructed by two mechanisms: elimination of energetically unfavored cylindrical micelle endcaps or perforation of disk-like micelles. Three-fold junctions were formed as intermediate structures to facilitate toroidal formation from cylindrical micelles. In order to construct toroids from cylindrical micelles, three requirements must be met: lower bending modulus (flexibility of cylinders), selfattraction between cylinders, and extra endcapping energy originating from chain packing frustration. Extremely high energy spheres can also fuse into toroids. Disk-like micelles can transform into a toroidal morphology when cylindrical packing geometry was initiated along the rims of disk-like micelles via solvent mixing that eventually perforated the disk center. The toroidal morphology can be kinetically trapped by either ridding the system of organic solvent or chemically crosslinking the PAA corona with EDDA via addition of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide methiodide (DPEM). The interaction of positively