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Sample records for receptors decreased nicotine

  1. Repeated administration of the GABAB receptor positive modulator BHF177 decreased nicotine self-administration, and acute administration decreased cue-induced reinstatement of nicotine seeking in rats.

    Science.gov (United States)

    Vlachou, Styliani; Guery, Sebastien; Froestl, Wolfgang; Banerjee, Deboshri; Benedict, Jessica; Finn, M G; Markou, Athina

    2011-05-01

    γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain and is implicated in the modulation of central reward processes. Acute or chronic administration of GABA(B) receptor agonists or positive modulators decreased self-administration of various drugs of abuse. Furthermore, GABA(B) receptor agonists inhibited cue-induced reinstatement of nicotine- and cocaine-seeking behavior. Because of their fewer adverse side effects compared with GABA(B) receptor agonists, GABA(B) receptor positive modulators are potentially improved therapeutic compounds for the treatment of drug dependence compared with agonists. We examined whether the acute effects of the GABA(B) receptor positive modulator N-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl]-2-methyl-5-[4-(trifluoromethyl)phenyl]-4-pyrimidinamine (BHF177) on nicotine self-administration and food-maintained responding under a fixed-ratio 5 schedule of reinforcement were maintained after repeated administration. The effects of acute BHF177 administration on cue-induced nicotine- and food-seeking behavior, a putative animal model of relapse, were also examined. Repeated administration of BHF177 for 14 days decreased nicotine self-administration, with small tolerance observed during the last 7 days of treatment, whereas BHF177 minimally affected food-maintained responding. Acute BHF177 administration dose-dependently blocked cue-induced reinstatement of nicotine-, but not food-, seeking behavior after a 10-day extinction period. These results showed that BHF177 selectively blocked nicotine self-administration and prevented cue-induced reinstatement of nicotine seeking, with minimal effects on responding for food and no effect on cue-induced reinstatement of food seeking. Thus, GABA(B) receptor positive modulators could be useful therapeutics for the treatment of different aspects of nicotine dependence by facilitating smoking cessation by decreasing nicotine intake and preventing relapse to smoking in humans.

  2. Positive Modulation of GABAB Receptors Decreased Nicotine Self-administration and Counteracted Nicotine-induced Enhancement of Brain Reward Function in Rats

    OpenAIRE

    Paterson, Neil E.; Vlachou, Styliani; Guery, Sebastien; Kaupmann, Klemens; Froestl, Wolfgang; Markou, Athina

    2008-01-01

    Acute administration of γ-aminobutyric acid (GABA)-B receptor agonists decreases nicotine, cocaine, ethanol, and heroin self-administration, and also decreases food-maintained responding and suppresses locomotor activity at high doses. GABAB receptor positive modulators may represent potentially improved therapeutic compounds because of their fewer side-effects than receptor agonists. The present study investigated the effects of administration of the GABAB receptor positive modulators 2,6-Di...

  3. Positive modulation of GABA(B) receptors decreased nicotine self-administration and counteracted nicotine-induced enhancement of brain reward function in rats.

    Science.gov (United States)

    Paterson, Neil E; Vlachou, Styliani; Guery, Sebastien; Kaupmann, Klemens; Froestl, Wolfgang; Markou, Athina

    2008-07-01

    Acute administration of gamma-aminobutyric acid (GABA)-B receptor agonists decreases nicotine, cocaine, ethanol, and heroin self-administration and also decreases food-maintained responding and suppresses locomotor activity at high doses. GABA(B) receptor-positive modulators may represent potentially improved therapeutic compounds because of their fewer side effects than receptor agonists. The present study investigated the effects of administration of the GABA(B) receptor-positive modulators 2,6-di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) and N-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl]-2-methyl-5-[4-(trifluoromethyl)phenyl]-4-pyrimidinamine (BHF177) and coadministration of the GABA(B) receptor-positive modulator N,N'-dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine (GS39783) with the GABA(B) receptor agonist (3-amino-2[S]-hydroxypropyl)-methylphosphinic acid (CGP44532) on nicotine- and food-maintained responding under fixed ratio (FR) 5 and progressive ratio schedules of reinforcement. Furthermore, the effects of BHF177 and CGP44532 on nicotine-induced enhancement of brain reward function were evaluated. The results indicated that administration of CGP7930 decreased nicotine self-administration under an FR5 schedule. Administration of either GS39783 or CGP44532 selectively decreased nicotine self-administration, whereas coadministration of these compounds had additive effects. BHF177 administration selectively decreased nicotine- but not food-maintained responding under FR5 and progressive ratio schedules. The nicotine-induced enhancement of brain reward function was blocked by BHF177 or CGP44532, although the highest doses of both compounds, particularly CGP44532, decreased brain reward function when administered alone, suggesting an additive, rather than interactive, effect. Overall, the present results indicate that GABA(B) receptor-positive modulators, similarly to GABA(B) receptor agonists, attenuated the reinforcing and reward

  4. Positive Modulation of GABAB Receptors Decreased Nicotine Self-administration and Counteracted Nicotine-induced Enhancement of Brain Reward Function in Rats

    Science.gov (United States)

    Paterson, Neil E.; Vlachou, Styliani; Guery, Sebastien; Kaupmann, Klemens; Froestl, Wolfgang; Markou, Athina

    2008-01-01

    Acute administration of γ-aminobutyric acid (GABA)-B receptor agonists decreases nicotine, cocaine, ethanol, and heroin self-administration, and also decreases food-maintained responding and suppresses locomotor activity at high doses. GABAB receptor positive modulators may represent potentially improved therapeutic compounds because of their fewer side-effects than receptor agonists. The present study investigated the effects of administration of the GABAB receptor positive modulators 2,6-Di-tert-butyl-4-(3-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930) and N-[(1R,2R,4S)-bicyclo[2.2.1]hept-2-yl]-2-methyl-5-[4-(trifluoromethyl)phenyl]-4-pyrimidinamine (BHF177), and co-administration of the GABAB receptor positive modulator N,N'-dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine (GS39783) with the GABAB receptor agonist (3-amino-2[S]-hydroxypropyl)-methylphosphinic acid (CGP44532) on nicotine- and food-maintained responding under fixed-ratio 5 (FR5) and progressive-ratio schedules of reinforcement. Furthermore, the effects of BHF177 and CGP44532 on nicotine-induced enhancement of brain reward function were evaluated. The results indicated that administration of CGP7930 decreased nicotine self-administration under an FR5 schedule. Administration of either GS39783 or CGP44532 selectively decreased nicotine self-administration, while co-administration of these compounds had additive effects. BHF177 administration selectively decreased nicotine-, but not food-, maintained responding under FR5 and progressive-ratio schedules. The nicotine-induced enhancement of brain reward function was blocked by BHF177 or CGP44532, although the highest doses of both compounds, particularly CGP44532, decreased brain reward function when administered alone, suggesting an additive, rather than interactive, effect. Overall, the present results indicate that GABAB receptor positive modulators, similarly to GABAB receptor agonists, attenuated the reinforcing and reward

  5. Nicotinic receptor agonists decrease L-dopa-induced dyskinesias most effectively in partially lesioned parkinsonian rats

    Science.gov (United States)

    Huang, Luping Z.; Campos, Carla; Ly, Jason; Carroll, F. Ivy; Quik, Maryka

    2011-01-01

    L-dopa therapy for Parkinson's disease leads to dyskinesias or abnormal involuntary movement (AIMs) for which there are few treatment options. Our previous data showed that nicotine administration reduced L-dopa-induced AIMs in parkinsonian monkeys and rats. To further understand how nicotine mediates its antidyskinetic action, we investigated the effect of nicotinic receptor (nAChR) agonists in unilateral 6-OHDA-lesioned rats with varying striatal damage. We first tested the drugs in L-dopa-treated rats with a near-complete striatal dopamine lesion (>99%), the standard rodent dyskinesia model. Varenicline, an agonist that interacts with multiple nAChRs, did not significantly reduce L-dopa-induced AIMs, while 5-iodo-A-85380 (A-85380), which acts selectively at α4β2* and α6β2* subtypes, reduced AIMs by 20%. By contrast, both varenicline and A-85380 reduced L-dopa-induced AIMs by 40–50% in rats with a partial striatal dopamine lesion. Neither drug worsened the antiparkinsonian action of L-dopa. The results show that selective nicotinic agonists reduce dyskinesias, and that they are optimally effective in animals with partial striatal dopamine damage. These findings suggest that presynaptic dopamine terminal α4β2* and α6β2* nAChRs are critical for nicotine’s antidyskinetic action. The current data have important implications for the use of nicotinic receptor-directed drugs for L-dopa-induced dyskinesias, a debilitating motor complication of dopamine replacement therapy for Parkinson’s disease. PMID:21232546

  6. Repeated Administration of the GABA\\(_B\\) Receptor Positive Modulator BHF177 Decreased Nicotine Self-Administration, and Acute Administration Decreased Cue-Induced Reinstatement of Nicotine Seeking in Rats

    OpenAIRE

    Vlachou, Styliani; Guery, Sebastien; Froestl, Wolfgang; Benedict, Jessica; Finn, M. G.; Markou, Athina; Banerjee, Deboshri

    2011-01-01

    Abstract: Rationale \\(\\gamma\\)-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain and is implicated in the modulation of central reward processes. Acute or chronic administration of GABA\\(_B\\) receptor agonists or positive modulators decreased self-administration of various drugs of abuse. Furthermore, GABA\\(_B\\) receptor agonists inhibited cue-induced reinstatement of nicotine- and cocaine-seeking behavior. Because of their fewer adverse side effects compared with...

  7. Nicotinic receptors, memory, and hippocampus.

    Science.gov (United States)

    Kutlu, Munir Gunes; Gould, Thomas J

    2015-01-01

    Nicotinic acetylcholine receptors (nAChRs) modulate the neurobiological processes underlying hippocampal learning and memory. In addition, nicotine's ability to desensitize and upregulate certain nAChRs may alter hippocampus-dependent memory processes. Numerous studies have examined the effects of nicotine on hippocampus-dependent learning, as well as the roles of low- and high-affinity nAChRs in mediating nicotine's effects on hippocampus-dependent learning and memory. These studies suggested that while acute nicotine generally acts as a cognitive enhancer for hippocampus-dependent learning, withdrawal from chronic nicotine results in deficits in hippocampus-dependent memory. Furthermore, these studies demonstrated that low- and high-affinity nAChRs functionally differ in their involvement in nicotine's effects on hippocampus-dependent learning. In the present chapter, we reviewed studies using systemic or local injections of acute or chronic nicotine, nAChR subunit agonists or antagonists; genetically modified mice; and molecular biological techniques to characterize the effects of nicotine on hippocampus-dependent learning.

  8. Nicotine decreases ethanol-induced dopamine signaling and increases self-administration via stress hormones

    National Research Council Canada - National Science Library

    Doyon, William M; Dong, Yu; Ostroumov, Alexey; Thomas, Alyse M; Zhang, Tao A; Dani, John A

    2013-01-01

    .... Blocking stress hormone receptors prior to nicotine exposure prevented all interactions with alcohol that we measured, including the increased inhibition onto dopamine neurons, the decreased dopamine...

  9. Effect of nicotine and nicotinic receptors on anxiety and depression.

    Science.gov (United States)

    Picciotto, Marina R; Brunzell, Darlene H; Caldarone, Barbara J

    2002-07-02

    Nicotine has been shown to have effects on anxiety and depression in both human and animal studies. These studies suggest that nicotinic acetylcholine receptors (nAChRs) can modulate the function of pathways involved in stress response, anxiety and depression in the normal brain, and that smoking can result in alterations of anxiety level and mood. The effects of nicotine are complex however, and nicotine treatment can be either anxiolytic or anxiogenic depending on the anxiety model tested, the route of nicotine administration and the time course of administration. The paradoxical effects of nicotine on emotionality are likely due to the broad expression of nAChRs throughout the brain, the large number of nAChR subtypes that have been identified and the ability of nicotine treatment to both activate and desensitize nAChRs. Activation of nAChRs has been shown to modulate many systems associated with stress response including stress hormone pathways, monoaminergic transmission and release of classical neurotransmitters throughout the brain. Local administration studies in animals have identified brain areas that may be involved in the anxiogenic and anxiolytic actions of nicotine including the lateral septum, the dorsal raphe nuclei, the mesolimbic dopamine system and the hippocampus. The ensemble of studies to date suggest that under certain conditions nicotine can act as an anxiolytic and an antidepressant, but that following chronic use, adaptations to nicotine can occur resulting in increased anxiety and depression following withdrawal.

  10. Inflammation decreases the level of alpha7 nicotinic acetylcholine receptors in the brain mitochondria and makes them more susceptible to apoptosis induction.

    Science.gov (United States)

    Lykhmus, Olena; Gergalova, Galyna; Zouridakis, Marios; Tzartos, Socrates; Komisarenko, Sergiy; Skok, Maryna

    2015-11-01

    α7 nicotinic acetylcholine receptors (α7 nAChRs) are involved in regulating inflammatory reactions, as well as the cell viability. They are expressed in both the plasma membrane and mitochondria of eukaryotic cells. Previously we found that neuroinflammation resulted in the decrease of α7 nAChR density in the brain of mice and was accompanied by accumulation of amyloid-beta (Aβ) peptides and memory impairment. In the present paper, it is shown that inflammation induced by either regular bacterial lipopolysaccharide (LPS) injections or immunizations with α7 nAChR extracellular domain (1-208) affected also the brain cell mitochondria. Using various modifications of sandwich ELISA, we observed the decrease of α7 nAChRs and accumulation of Aβ(1-40) and Aβ(1-42) in mitochondria of immunized or LPS-treated mice compared to control ones. Mitochondria of treated mice responded with cytochrome c release to lower Ca(2+) concentrations than mitochondria of control mice and were less sensitive to its attenuation with α7 nAChR agonist PNU282987. It is concluded that inflammation decreases α7 nAChR expression in both mitochondria and cell plasma membrane and makes mitochondria more susceptible to apoptosis induction. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Decrease in neuronal nicotinic acetylcholine receptor subunit and PSD-93 transcript levels in the male mouse MPG after cavernous nerve injury or explant culture

    Science.gov (United States)

    Girard, Beatrice M.; Merriam, Laura A.; Tompkins, John D.; Vizzard, Margaret A.

    2013-01-01

    Quantitative real-time PCR was used to test whether cavernous nerve injury leads to a decrease in major pelvic ganglia (MPG) neuronal nicotinic ACh receptor (nAChR) subunit and postsynaptic density (PSD)-93 transcript levels. Subunits α3, β4, and α7, commonly expressed in the MPG, were selected for analysis. After 72 h in explant culture, MPG transcript levels for α3, β4, α7, and PSD-93 were significantly depressed. Three days after cavernous nerve axotomy or crush in vivo, transcript levels for α3, β4, and PSD-93, but not for α7, were significantly depressed. Three days after dissection of the cavernous nerve free of underlying tissue and application of a 5-mm lateral stretch (manipulation), transcript levels for α3 and PSD-93 were also significantly decreased. Seven days after all three surgical procedures, α3 transcript levels remained depressed, but PSD-93 transcript levels were still decreased only after axotomy or nerve crush. At 30 days postsurgery, transcript levels for the nAChR subunits and PSD-93 had recovered. ACh-induced currents were significantly smaller in MPG neurons dissociated from 3-day explant cultured ganglia than from those recorded in neurons dissociated from acutely isolated ganglia; this observation provides direct evidence showing that a decrease in nAChR function was coincident with a decrease in nAChR subunit transcript levels. We conclude that a downregulation of nAChR subunit and PSD-93 expression after cavernous nerve injury, or even manipulation, could interrupt synaptic transmission within the MPG and thus contribute to the loss of neural control of urogenital organs after pelvic surgeries. PMID:24049141

  12. Nicotinic Receptors in the Habenulo-Interpeduncular System Are Necessary for Nicotine Withdrawal in Mice

    National Research Council Canada - National Science Library

    Salas, Ramiro; Sturm, Renea; Boulter, Jim; De Biasi, Mariella

    2009-01-01

    .... Nicotine withdrawal symptoms can also be observed in rodents. A major standing question is which nicotinic receptor subtypes and which areas of the brain are necessary for nicotine withdrawal to occur...

  13. Cholinergic modulation of dopamine pathways through nicotinic acetylcholine receptors.

    NARCIS (Netherlands)

    de Kloet, S.F.; Mansvelder, H.D.; de Vries, T.J.

    2015-01-01

    Nicotine addiction is highly prevalent in current society and is often comorbid with other diseases. In the central nervous system, nicotine acts as an agonist for nicotinic acetylcholine receptors (nAChRs) and its effects depend on location and receptor composition. Although nicotinic receptors are

  14. Decreased cerebral {alpha}4{beta}2* nicotinic acetylcholine receptor availability in patients with mild cognitive impairment and Alzheimer's disease assessed with positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kendziorra, Kai; Meyer, Philipp Mael; Barthel, Henryk; Hesse, Swen; Becker, Georg Alexander; Luthardt, Julia; Schildan, Andreas; Patt, Marianne; Sorger, Dietlind; Seese, Anita; Sabri, Osama [University of Leipzig, Department of Nuclear Medicine, Leipzig (Germany); Wolf, Henrike [University of Leipzig, Department of Psychiatry, Leipzig (Germany); University of Zurich, Department of Old Age Psychiatry and Psychiatry Research, Psychiatric University Hospital (PUK) Zurich, Zurich (Switzerland); Gertz, Herman-Josef [University of Leipzig, Department of Psychiatry, Leipzig (Germany)

    2011-03-15

    Postmortem studies indicate a loss of nicotinic acetylcholine receptor (nAChRs) in Alzheimer's disease (AD). In order to establish whether these changes in the cholinergic system occur at an early stage of AD, we carried out positron emission tomography (PET) with a specific radioligand for the {alpha}4{beta}2* nicotinic acetylcholine receptor ({alpha}4{beta}2* nAChR) in patients with mild to moderate AD and in patients with amnestic mild cognitive impairment (MCI), who have a high risk to progress to AD. Nine patients with moderate AD, eight patients with MCI and seven age-matched healthy controls underwent 2-[{sup 18}F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[{sup 18}F]FA-85380) PET. After coregistration with individual magnetic resonance imaging the binding potential (BP{sub ND}) of 2-[{sup 18}F]FA-85380 was calculated using either the corpus callosum or the cerebellum as reference regions. PET data were analysed by region of interest analysis and by voxel-based analysis. Both patients with AD and MCI showed a significant reduction in 2-[{sup 18}F]FA-85380 BP{sub ND} in typical AD-affected brain regions. Thereby, the corpus callosum was identified as the most suitable reference region. The 2-[{sup 18}F]FA-85380 BP{sub ND} correlated with the severity of cognitive impairment. Only MCI patients that converted to AD in the later course (n = 5) had a reduction in 2-[{sup 18}F]FA-85380 BP{sub ND}. 2-[{sup 18}F]FA-85380 PET appears to be a sensitive and feasible tool for the detection of a reduction in {alpha}4{beta}2* nAChRs which seems to be an early event in AD. In addition, 2-[{sup 18}F]FA-85380 PET might give prognostic information about a conversion from MCI to AD. (orig.)

  15. Replicated Risk Nicotinic Cholinergic Receptor Genes for Nicotine Dependence.

    Science.gov (United States)

    Zuo, Lingjun; Garcia-Milian, Rolando; Guo, Xiaoyun; Zhong, Chunlong; Tan, Yunlong; Wang, Zhiren; Wang, Jijun; Wang, Xiaoping; Kang, Longli; Lu, Lu; Chen, Xiangning; Li, Chiang-Shan R; Luo, Xingguang

    2016-11-07

    It has been hypothesized that the nicotinic acetylcholine receptors (nAChRs) play important roles in nicotine dependence (ND) and influence the number of cigarettes smoked per day (CPD) in smokers. We compiled the associations between nicotinic cholinergic receptor genes (CHRNs) and ND/CPD that were replicated across different studies, reviewed the expression of these risk genes in human/mouse brains, and verified their expression using independent samples of both human and mouse brains. The potential functions of the replicated risk variants were examined using cis-eQTL analysis or predicted using a series of bioinformatics analyses. We found replicated and significant associations for ND/CPD at 19 SNPs in six genes in three genomic regions (CHRNB3-A6, CHRNA5-A3-B4 and CHRNA4). These six risk genes are expressed in at least 18 distinct areas of the human/mouse brain, with verification in our independent human and mouse brain samples. The risk variants might influence the transcription, expression and splicing of the risk genes, alter RNA secondary or protein structure. We conclude that the replicated associations between CHRNB3-A6, CHRNA5-A3-B4,CHRNA4 and ND/CPD are very robust. More research is needed to examine how these genetic variants contribute to the risk for ND/CPD.

  16. Nicotine acts on growth plate chondrocytes to delay skeletal growth through the alpha7 neuronal nicotinic acetylcholine receptor.

    Directory of Open Access Journals (Sweden)

    Atsuo Kawakita

    Full Text Available BACKGROUND: Cigarette smoking adversely affects endochondral ossification during the course of skeletal growth. Among a plethora of cigarette chemicals, nicotine is one of the primary candidate compounds responsible for the cause of smoking-induced delayed skeletal growth. However, the possible mechanism of delayed skeletal growth caused by nicotine remains unclarified. In the last decade, localization of neuronal nicotinic acetylcholine receptor (nAChR, a specific receptor of nicotine, has been widely detected in non-excitable cells. Therefore, we hypothesized that nicotine affect growth plate chondrocytes directly and specifically through nAChR to delay skeletal growth. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of nicotine on human growth plate chondrocytes, a major component of endochondral ossification. The chondrocytes were derived from extra human fingers. Nicotine inhibited matrix synthesis and hypertrophic differentiation in human growth plate chondrocytes in suspension culture in a concentration-dependent manner. Both human and murine growth plate chondrocytes expressed alpha7 nAChR, which constitutes functional homopentameric receptors. Methyllycaconitine (MLA, a specific antagonist of alpha7 nAChR, reversed the inhibition of matrix synthesis and functional calcium signal by nicotine in human growth plate chondrocytes in vitro. To study the effect of nicotine on growth plate in vivo, ovulation-controlled pregnant alpha7 nAChR +/- mice were given drinking water with or without nicotine during pregnancy, and skeletal growth of their fetuses was observed. Maternal nicotine exposure resulted in delayed skeletal growth of alpha7 nAChR +/+ fetuses but not in alpha7 nAChR -/- fetuses, implying that skeletal growth retardation by nicotine is specifically mediated via fetal alpha7 nAChR. CONCLUSIONS/SIGNIFICANCE: These results suggest that nicotine, from cigarette smoking, acts directly on growth plate chondrocytes to decrease

  17. Nicotine-induced upregulation of native neuronal nicotinic receptors is caused by multiple mechanisms

    Science.gov (United States)

    Govind, Anitha P.; Walsh, Heather; Green, William N.

    2012-01-01

    Nicotine causes changes in brain nicotinic acetylcholine receptors (nAChRs) during smoking that initiate addiction. Nicotine-induced upregulation is the long-lasting increase in nAChR radio-ligand binding sites in brain resulting from exposure. The mechanisms causing upregulation are not established. Many different mechanisms have been reported with the assumption that there is a single, underlying cause. Using live cortical neurons, we examined for the first time how exposure and withdrawal of nicotine shape the kinetics of native α4β2-containing nAChR upregulation in real time. Upregulation kinetics demonstrate that at least two different mechanisms underlie this phenomenon. First, a transient upregulation occurs that rapidly reverses, faster than nAChR degradation, and corresponds to nAChR conformational changes as assayed by conformational-dependent, subunit-specific antibodies. Second, a long-lasting process occurs correlating with increases in nAChR numbers caused by decreased proteasomal subunit degradation. Previous radio-ligand binding measurements to brain tissue have measured the second process and largely missed the first. We conclude that nicotine-induced upregulation is composed of multiple processes occurring at different rates with different underlying causes. PMID:22323734

  18. Drug-dependent behaviors and nicotinic acetylcholine receptor expressions in Caenorhabditis elegans following chronic nicotine exposure.

    Science.gov (United States)

    Polli, Joseph R; Dobbins, Dorothy L; Kobet, Robert A; Farwell, Mary A; Zhang, Baohong; Lee, Myon-Hee; Pan, Xiaoping

    2015-03-01

    Nicotine, the major psychoactive compound in tobacco, targets nicotinic acetylcholine receptors (nAChRs) and results in drug dependence. The nematode Caenorhabditis elegans' (C. elegans) genome encodes conserved and extensive nicotinic receptor subunits, representing a useful system to investigate nicotine-induced nAChR expressions in the context of drug dependence. However, the in vivo expression pattern of nAChR genes under chronic nicotine exposure has not been fully investigated. To define the role of nAChR genes involved in nicotine-induced locomotion changes and the development of tolerance to these effects, we characterized the locomotion behavior combining the use of two systems: the Worm Tracker hardware and the WormLab software. Our results indicate that the combined system is an advantageous alternative to define drug-dependent locomotion behavior in C. elegans. Chronic (24-h dosing) nicotine exposure at 6.17 and 61.7μM induced nicotine-dependent behaviors, including drug stimulation, tolerance/adaption, and withdrawal responses. Specifically, the movement speed of naïve worms on nicotine-containing environments was significantly higher than on nicotine-free environments, suggesting locomotion stimulation by nicotine. In contrast, the 24-h 6.17μM nicotine-treated worms exhibited significantly higher speeds on nicotine-free plates than on nicotine-containing plates. Furthermore significantly increased locomotion behavior during nicotine cessation was observed in worms treated with a higher nicotine concentration of 61.7μM. The relatively low locomotion speed of nicotine-treated worms on nicotine-containing environments also indicates adaption/tolerance of worms to nicotine following chronic nicotine exposure. In addition, this study provides useful information regarding the comprehensive in vivo expression profile of the 28 "core" nAChRs following different dosages of chronic nicotine treatments. Eleven genes (lev-1, acr-6, acr-7, acr-11, lev-8, acr

  19. Docking to flexible nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Sander, Tommy; Bruun, Anne T; Balle, Thomas

    2010-01-01

    Computational docking to nicotinic acetylcholine receptors (nAChRs) and other members of the Cys-loop receptor family is complicated by the flexibility of the so-called C-loop. As observed in the large number of published crystal structures of the acetylcholine binding protein (AChBP), a structural...... surrogate and homology modeling template for the nAChRs, the conformation of this loop is controlled by the ligand present in the binding pocket. As part of the development of a protocol for unbiased docking to the nAChRs, we here present the results of docking of ligands with known binding modes to an ACh...

  20. Nicotine increases stress-induced serotonin release by stimulating nicotinic acetylcholine receptor in rat striatum.

    Science.gov (United States)

    Takahashi, H; Takada, Y; Nagai, N; Urano, T; Takada, A

    1998-03-01

    We used a microdialysis technique to analyze the effects of footshock stress on the release of serotonin (5-hydroxytryptamine: 5-HT) in the striatum or prefrontal cortex (PFC) in rats that were pretreated with nicotine. Neither nicotine administration alone nor stress application alone changed 5-HT release. During stress application, however, both chronic nicotine administration and local infusion of nicotine to the striatum significantly increased 5-HT release in the striatum, though not in the PFC. These increases in 5-HT release were eradicated by a local infusion of mecamylamine. Release of 5-HT increased in the striatum during stress application when nicotine was injected to the striatum, while nicotinic injection to the dorsal raphe nucleus did not increase 5-HT release in the striatum. The present study demonstrates that nicotine induced a release of 5-HT upon stress application by stimulating presynaptic nicotinic receptors in the striatum.

  1. Cholinergic modulation of dopamine pathways through nicotinic acetylcholine receptors.

    Science.gov (United States)

    de Kloet, Sybren F; Mansvelder, Huibert D; De Vries, Taco J

    2015-10-15

    Nicotine addiction is highly prevalent in current society and is often comorbid with other diseases. In the central nervous system, nicotine acts as an agonist for nicotinic acetylcholine receptors (nAChRs) and its effects depend on location and receptor composition. Although nicotinic receptors are found in most brain regions, many studies on addiction have focused on the mesolimbic system and its reported behavioral correlates such as reward processing and reinforcement learning. Profound modulatory cholinergic input from the pedunculopontine and laterodorsal tegmentum to dopaminergic midbrain nuclei as well as local cholinergic interneuron projections to dopamine neuron axons in the striatum may play a major role in the effects of nicotine. Moreover, an indirect mesocorticolimbic feedback loop involving the medial prefrontal cortex may be involved in behavioral characteristics of nicotine addiction. Therefore, this review will highlight current understanding of the effects of nicotine on the function of mesolimbic and mesocortical dopamine projections in the mesocorticolimbic circuit. Copyright © 2015. Published by Elsevier Inc.

  2. Glial cell-derived neurotrophic factor alleviates sepsis-induced neuromuscular dysfunction by decreasing the expression of γ- and α7-nicotinic acetylcholine receptors in an experimental rat model of neuromyopathy.

    Science.gov (United States)

    Wang, Xin; Min, Su; Xie, Fei; Yang, Jun; Li, Liang; Chen, Jingyuan

    2018-02-05

    Sepsis-induced neuromuscular dysfunction results from up-regulation of the expression of γ- and α7-nicotinic acetylcholine receptors (nAChR). Although glial cell derived neurotrophic factor (GDNF) has been implicated in repairing and supporting neurons, little is known about the effects of GDNF on demyelination of nerves in sepsis. In this study, we tested the hypothesis that GDNF could alleviate sepsis-induced neuromuscular dysfunction by decreasing the expression of γ- and α7-nAChR in an experimental rat model of neuromyopathy. Rats were randomly divided into a sham group and a sepsis group. Levels of inflammatory factors, muscle function, and nicotinic acetylcholine receptors were tested in rats after cecal ligation and puncture (CLP). At 24 h after CLP, GDNF was injected around the sciatic nerve of sepsis rats, cytokines were detected by enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining was used to detect the expression of nAChRs. GDNF and its downstream effector (Erk1/2 and GFR-α), neuregulin-1 (NRG-1) and γ- and α7-nAChR were measured using Western blot analysis. The expression of GDNF reached a minimum at 24 h after CLP. Compared with the sham group, the release of cytokines and the expression of γ- and α7-nAChR were significantly increased in the sepsis group. The administration of GDNF significantly alleviated sepsis-induced neuromuscular dysfunction, as well as reducing the expression of γ- and α7-nAChR. In addition, the expression of Erk1/2, GFR-α, NRG-1 were significantly increased after GDNF treatment. GDNF administration may improve patient outcomes by reducing the demyelination of nerves and the expression of γ- and α7-nAChR. Copyright © 2018. Published by Elsevier Inc.

  3. Expression and function of nicotinic acetylcholine receptors in stem cells

    Directory of Open Access Journals (Sweden)

    Herman S. Cheung

    2016-07-01

    Full Text Available Nicotinic acetylcholine receptors are prototypical ligand gated ion channels typically found in muscular and neuronal tissues. Functional nicotinic acetylcholine receptors, however, have also recently been identified on other cell types, including stem cells. Activation of these receptors by the binding of agonists like choline, acetylcholine, or nicotine has been implicated in many cellular changes. In regards to stem cell function, nicotinic acetylcholine receptor activation leads to changes in stem cell proliferation, migration and differentiation potential. In this review we summarize the expression and function of known nicotinic acetylcholine receptors in different classes of stem cells including: pluripotent stem cells, mesenchymal stem cells, periodontal ligament derived stem cells, and neural progenitor cells and discuss the potential downstream effects of receptor activation on stem cell function.

  4. The role of adrenergic receptors in nicotine-induced hyperglycemia ...

    African Journals Online (AJOL)

    The role of adrenergic receptors in nicotine-induced hyperglycaemia has not been well studied in amphibians. Thus, this study investigates the effects of alpha and beta adrenergic receptor blockers in nicotine-induced hyperglycaemia in the common African toad Bufo regularis. Toads fasted for 24 h were anaesthetized with ...

  5. Parazoanthoxanthin A blocks Torpedo nicotinic acetylcholine receptors.

    Science.gov (United States)

    Rozman, Klara Bulc; Araoz, Romulo; Sepcić, Kristina; Molgo, Jordi; Suput, Dusan

    2010-09-06

    Nicotinic acetylcholine receptors are implicated in different nervous system-related disorders, and their modulation could improve existing therapy of these diseases. Parazoanthoxanthin A (ParaA) is a fluorescent pigment of the group of zoanthoxanthins. Since it is a potent acetylcholinesterase inhibitor, it may also bind to nicotinic acetylcholine receptors (nAChRs). For this reason its effect on Torpedo nAChR (alpha1(2)betagammadelta) transplanted to Xenopus laevis oocytes was evaluated, using the voltage-clamp technique. ParaA dose-dependently reduced the acetylcholine-induced currents. This effect was fully reversible only at lower concentrations. ParaA also reduced the Hill coefficient and the time to peak current, indicating a channel blocking mode of action. On the other hand, the combined effect of ParaA and d-tubocurarine (d-TC) on acetylcholine-induced currents exhibited only partial additivity, assuming a competitive mode of action of ParaA on nAChR. These results indicate a dual mode of action of ParaA on the Torpedo AChR. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

  6. Microbial Biofertilizer Decreases Nicotine Content by Improving Soil Nitrogen Supply.

    Science.gov (United States)

    Shang, Cui; Chen, Anwei; Chen, Guiqiu; Li, Huanke; Guan, Song; He, Jianmin

    2017-01-01

    Biofertilizers have been widely used in many countries for their benefit to soil biological and physicochemical properties. A new microbial biofertilizer containing Phanerochaete chrysosporium and Bacillus thuringiensis was prepared to decrease nicotine content in tobacco leaves by regulating soil nitrogen supply. Soil NO 3 - -N, NH 4 + -N, nitrogen supply-related enzyme activities, and nitrogen accumulation in plant leaves throughout the growing period were investigated to explore the mechanism of nicotine reduction. The experimental results indicated that biofertilizer can reduce the nicotine content in tobacco leaves, with a maximum decrement of 16-18 % in mature upper leaves. In the meantime, the total nitrogen in mature lower and middle leaves increased with the application of biofertilizer, while an opposite result was observed in upper leaves. Protein concentration in leaves had similar fluctuation to that of total nitrogen in response to biofertilizer. NO 3 - -N content and nitrate reductase activity in biofertilizer-amended soil increased by 92.3 and 42.2 %, respectively, compared to those in the control, whereas the NH 4 + -N and urease activity decreased by 37.8 and 29.3 %, respectively. Nitrogen uptake was improved in the early growing stage, but this phenomenon was not observed during the late growth period. Nicotine decrease is attributing to the adjustment of biofertilizer in soil nitrogen supply and its uptake in tobacco, which result in changes of nitrogen content as well as its distribution in tobacco leaves. The application of biofertilizer containing P. chrysosporium and B. thuringiensis can reduce the nicotine content and improve tobacco quality, which may provide some useful information for tobacco cultivation.

  7. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, S.V.; Changeux, J.P.; Granon, S. [Unite de Neurobiologie Integrative du Systeme Cholinergique, URA CNRS 2182, Institut Pasteur, Departement de Neuroscience, 25 rue du Dr Roux, 75015 Paris (France); Amadon, A.; Giacomini, E.; Le Bihan, D. [Service Hospitalier Frederic Joliot, 4 place du general Leclerc, 91400 Orsay (France); Wiklund, A. [Section of Anaesthesiology and Intensive Care Medicine, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm (Sweden)

    2009-07-01

    Rationale: The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity {beta}2-containing nicotinic receptors ({beta}2*nAChRs) are located. Objectives We intend to see which brain circuits are activated when nicotine is given in animals naive for nicotine and whether the {beta}2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. Materials and methods: We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and {beta}2 knockout (KO) mice. Results: Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, {beta}2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via {alpha}7 nicotinic receptors. Conclusions: Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on {beta}2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice. (authors)

  8. The α7 nicotinic acetylcholine receptor complex

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Mikkelsen, Jens D

    2012-01-01

    The α7 nicotinic acetylcholine receptor (nAChR) is a promising drug target for a number of diseases ranging from schizophrenia and Alzheimer's disease to chronic pain and inflammatory diseases. Focusing on the central nervous system, we describe how endogenous and experimental compounds...... in diseases such as schizophrenia and Alzheimer's disease. Furthermore, α7 nAChR agonists and allosteric modulators differentially alter expression and functionality of the α7 nAChR with repeated administration, which suggests that there may be fundamentally different outcomes of long-term administration...... with these different types of compounds. Finally, we describe the special case of Aβ1-42 binding to the α7 nAChR, which may pose a unique challenge to drug development of α7 nAChR-specific ligands for Alzheimer's disease. Hopefully, a greater knowledge of the many factors influencing α7 nAChR function as well...

  9. Impulsive behavior and nicotinic acetylcholine receptors.

    Science.gov (United States)

    Ohmura, Yu; Tsutsui-Kimura, Iku; Yoshioka, Mitsuhiro

    2012-01-01

    Higher impulsivity is thought to be a risk factor for drug addiction, criminal involvement, and suicide. Excessive levels of impulsivity are often observed in several psychiatric disorders including attention-deficit/hyperactivity disorder and schizophrenia. Previous studies have demonstrated that nicotinic acetylcholine receptors (nAChRs) are involved in impulsive behavior. Here, we introduce recent advances in this field and describe the role of the following nAChR-related brain mechanisms in modulating impulsive behavior: dopamine release in the ventral striatum; α4β2 nAChRs in the infralimbic cortex, which is a ventral part of the medial prefrontal cortex (mPFC); and dopamine release in the mPFC. We also suggest several potential therapeutic drugs to address these mechanisms in impulsivity-related disorders and explore future directions to further elucidate the roles of central nAChRs in impulsive behavior.

  10. Nicotine induces fibrogenic changes in human liver via nicotinic acetylcholine receptors expressed on hepatic stellate cells

    Energy Technology Data Exchange (ETDEWEB)

    Soeda, Junpei; Morgan, Maelle; McKee, Chad; Mouralidarane, Angelina; Lin, ChingI [University College London, Centre for Hepatology, Royal Free Hospital, London NW3 2PF (United Kingdom); Roskams, Tania [Department of Morphology and Molecular Pathology, University of Leuven (Belgium); Oben, Jude A., E-mail: j.oben@ucl.ac.uk [University College London, Centre for Hepatology, Royal Free Hospital, London NW3 2PF (United Kingdom); Department of Gastroenterology and Hepatology, Guy' s and St Thomas' Hospital, London SE1 7EH (United Kingdom)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Cigarette smoke may induce liver fibrosis via nicotine receptors. Black-Right-Pointing-Pointer Nicotine induces proliferation of hepatic stellate cells (HSCs). Black-Right-Pointing-Pointer Nicotine activates hepatic fibrogenic pathways. Black-Right-Pointing-Pointer Nicotine receptor antagonists attenuate HSC proliferation. Black-Right-Pointing-Pointer Nicotinic receptor antagonists may have utility as novel anti-fibrotic agents. -- Abstract: Background and aims: Cigarette smoke (CS) may cause liver fibrosis but possible involved mechanisms are unclear. Among the many chemicals in CS is nicotine - which affects cells through nicotinic acetylcholine receptors (nAChR). We studied the effects of nicotine, and involved pathways, on human primary hepatic stellate cells (hHSCs), the principal fibrogenic cells in the liver. We then determined possible disease relevance by assaying nAChR in liver samples from human non-alcoholic steatohepatitis (NASH). Methods: hHSC were isolated from healthy human livers and nAChR expression analyzed - RT-PCR and Western blotting. Nicotine induction of hHSC proliferation, upregulation of collagen1-{alpha}2 and the pro-fibrogenic cytokine transforming growth factor beta 1 (TGF-{beta}1) was determined along with involved intracellular signaling pathways. nAChR mRNA expression was finally analyzed in whole liver biopsies obtained from patients diagnosed with non-alcoholic steatohepatitis (NASH). Results: hHSCs express muscle type ({alpha}1, {beta}1, delta and epsilon) and neuronal type ({alpha}3, {alpha}6, {alpha}7, {beta}2 and {beta}4) nAChR subunits at the mRNA level. Among these subunits, {alpha}3, {alpha}7, {beta}1 and {epsilon} were predominantly expressed as confirmed by Western blotting. Nicotine induced hHSC proliferation was attenuated by mecamylamine (p < 0.05). Additionally, collagen1-{alpha}2 and TGF-{beta}1 mRNA expression were significantly upregulated by nicotine and inhibited by

  11. Receptor systems participating in nicotine-specific effects.

    Science.gov (United States)

    Sziráki, I; Sershen, H; Benuck, M; Hashim, A; Lajtha, A

    1998-11-01

    It is generally accepted that self-administration of drugs is prompted primarily by a reward system driven by an increase in extracellular dopamine in the nucleus accumbens. Recent findings that dopamine increase in the accumbens can be caused by many other factors, among them stress, suggest a more complex mechanism, and possibly differences in the reward system for different compounds. In the present paper we compare the effects of receptor-specific antagonists on the increase of dopamine induced by nicotine with that induced by cocaine in the nucleus accumbens in conscious rats. The compounds alone or together were injected intravenously, and dopamine level changes were measured via microdialysis. When administered together the effect of nicotine and cocaine on the level of dopamine in the accumbens was additive. Apparently there is some interaction between the two compounds, since nicotine had no effect after combined nicotine and cocaine administration. Perhaps the available dopamine pool was exhausted by the prior administration. The nicotinic antagonist mecamylamine, the muscarinic antagonist atropine, and the NMDA glutamate receptor antagonist MK-801 each blocked nicotine-induced dopamine release in the accumbens, indicating the participation of more than a single receptor system in the nicotine-induced effect. These three antagonists did not inhibit cocaine-induced dopamine increase in the accumbens, indicating the lack of a role of these receptors in the cocaine effect under our experimental conditions. SCH-23390, a dopamine D1 receptor antagonist, blocked both nicotine- and cocaine-induced effects, indicating the possible role of this receptor in these reward effects. The results indicate that there are differences in some of the receptors mediating the central effects of the two compounds examined, nicotine and cocaine, although each influences dopamine levels, and that the two compounds interact.

  12. Functional interaction between Lypd6 and nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Arvaniti, Maria; Jensen, Majbrit M; Soni, Neeraj

    2016-01-01

    Nicotinic acetylcholine receptors (nAChRs) affect multiple physiological functions in the brain and their functions are modulated by regulatory proteins of the Lynx family. Here, we report for the first time a direct interaction of the Lynx protein LY6/PLAUR domain-containing 6 (Lypd6) with n...... findings suggest that Lypd6 is a versatile inhibitor of cholinergic signaling in the brain, and that Lypd6 is dysregulated by nicotine exposure during early development. Regulatory proteins of the Lynx family modulate the function of nicotinic receptors (nAChRs). We report for the first time that the Lynx...

  13. Nicotine receptor partial agonists for smoking cessation

    Directory of Open Access Journals (Sweden)

    Kate Cahill

    Full Text Available BACKGROUND: Nicotine receptor partial agonists may help people to stop smoking by a combination of maintaining moderate levels of dopamine to counteract withdrawal symptoms (acting as an agonist and reducing smoking satisfaction (acting as an antagonist. OBJECTIVES: The primary objective of this review is to assess the efficacy and tolerability of nicotine receptor partial agonists, including cytisine, dianicline and varenicline for smoking cessation. SEARCH METHODS: We searched the Cochrane Tobacco Addiction Group's specialised register for trials, using the terms ('cytisine' or 'Tabex' or 'dianicline' or 'varenicline' or 'nicotine receptor partial agonist' in the title or abstract, or as keywords. The register is compiled from searches of MEDLINE, EMBASE, PsycINFO and Web of Science using MeSH terms and free text to identify controlled trials of interventions for smoking cessation and prevention. We contacted authors of trial reports for additional information where necessary. The latest update of the specialized register was in December 2011. We also searched online clinical trials registers. SELECTION CRITERIA: We included randomized controlled trials which compared the treatment drug with placebo. We also included comparisons with bupropion and nicotine patches where available. We excluded trials which did not report a minimum follow-up period of six months from start of treatment. DATA COLLECTION AND ANALYSIS: We extracted data on the type of participants, the dose and duration of treatment, the outcome measures, the randomization procedure, concealment of allocation, and completeness of follow-up. The main outcome measured was abstinence from smoking at longest follow-up. We used the most rigorous definition of abstinence, and preferred biochemically validated rates where they were reported. Where appropriate we pooled risk ratios (RRs, using the Mantel-Haenszel fixed-effect model. MAIN RESULTS: Two recent cytisine trials (937 people

  14. Effect of chronic (-)-nicotine treatment on rat cerebral benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Magata, Yasuhiro E-mail: magata@kuhp.kyoto-u.ac.jp; Kitano, Haruhiro; Shiozaki, Toshiki; Iida, Yasuhiko; Nishizawa, Sadahiko; Saji, Hideo; Konishi, Junji

    2000-01-01

    The purpose of this study was to clarify the effect of (-)-nicotine on cerebral benzodiazepine receptors (BzR) with radiotracer methods. The effect of (-)-nicotine on BzR was examined in in vitro studies using chronic (-)-nicotine-treated rats using {sup 3}H-diazepam. The in vitro radioreceptor assay showed a 14% increase in the maximum number of binding sites of BzR in chronic (-)-nicotine-treated rats in comparison with the control rats. Moreover, a convenient in vivo uptake index of {sup 125}I-iomazenil was calculated and a higher uptake of the radioactivity was observed in the chronic (-)-nicotine-treated group than in the control group. Although further studies of the mechanism of (-)-nicotine on such BzR changes are required, an increase in the amount of BzR in the cerebral cortex was found in rats that underwent chronic (-)-nicotine treatment, and this result contributed to the understanding of the effects of (-)-nicotine and smoking on neural functions.

  15. Insect nicotinic acetylcholine receptors (nAChRs): Important amino ...

    African Journals Online (AJOL)

    Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels which mediate fast cholinergic synaptic transmission in insect and vertebrate nervous systems. The great abundance of nAChRs within the insect central nervous system has led to the development of insecticides targeting these receptors, such as ...

  16. A Synthetic Receptor for Nicotine from a Dynamic Combinatorial Library

    NARCIS (Netherlands)

    Hamieh, Saleh; Ludlow, R. Frederick; Perraud, Olivier; West, Kevin R.; Mattia, Elio; Otto, Sijbren

    2012-01-01

    Designing synthetic receptors that bind biologically relevant guests in an aqueous solution remains a considerable challenge. We now report a new synthetic receptor for nicotine, selected from a dynamic combinatorial library, that binds this guest in water at neutral pH through a combination of

  17. Chronic nicotine modifies skeletal muscle Na,K-ATPase activity through its interaction with the nicotinic acetylcholine receptor and phospholemman.

    Directory of Open Access Journals (Sweden)

    Alexander V Chibalin

    Full Text Available Our previous finding that the muscle nicotinic acetylcholine receptor (nAChR and the Na,K-ATPase interact as a regulatory complex to modulate Na,K-ATPase activity suggested that chronic, circulating nicotine may alter this interaction, with long-term changes in the membrane potential. To test this hypothesis, we chronically exposed rats to nicotine delivered orally for 21-31 days. Chronic nicotine produced a steady membrane depolarization of ∼3 mV in the diaphragm muscle, which resulted from a net change in electrogenic transport by the Na,K-ATPase α2 and α1 isoforms. Electrogenic transport by the α2 isoform increased (+1.8 mV while the activity of the α1 isoform decreased (-4.4 mV. Protein expression of Na,K-ATPase α1 or α2 isoforms and the nAChR did not change; however, the content of α2 subunit in the plasma membrane decreased by 25%, indicating that its stimulated electrogenic transport is due to an increase in specific activity. The physical association between the nAChR, the Na,K-ATPase α1 or α2 subunits, and the regulatory subunit of the Na,K-ATPase, phospholemman (PLM, measured by co-immuno precipitation, was stable and unchanged. Chronic nicotine treatment activated PKCα/β2 and PKCδ and was accompanied by parallel increases in PLM phosphorylation at Ser(63 and Ser(68. Collectively, these results demonstrate that nicotine at chronic doses, acting through the nAChR-Na,K-ATPase complex, is able to modulate Na,K-ATPase activity in an isoform-specific manner and that the regulatory range includes both stimulation and inhibition of enzyme activity. Cholinergic modulation of Na,K-ATPase activity is achieved, in part, through activation of PKC and phosphorylation of PLM.

  18. Nicotinic receptor partial agonists alter catecholamine homeostasis and response to nicotine in PC12 cells.

    Science.gov (United States)

    Turcanu, D S; Kirtok, N; Eibl, C; Guendisch, D; LaGamma, E F; Nankova, B B

    2012-05-16

    Repeated stress is a major public health concern where many stress responses are mediated by neuronal nicotinic acetylcholine receptors. In the present study we evaluated the effects of the nicotinic receptor partial agonists, cytisine and its derivative 3-(pyridin-3'-yl)-cytisine (3-pyr-Cyt) on two main biological outputs associated with activation of nAChR-release of neurotransmitters and increase in catecholamine biosynthesis to replenish the releasable pool. We compared these substances to the maximal response triggered by nicotine (full agonist) in PC12 cells. Cytisine, 3-pyr-Cyt or nicotine induced time-, dose- and Ca(2+)-dependent significant release of norepinephrine (NE) into the culture media. These effects were completely inhibited by mecamylamine but not by α-bungarotoxin, and only partially affected by α-conotoxin AulB, consistent with the involvement of α3β4 receptors. Co-application of cytisine (or 3-pyr-Cyt) and nicotine resulted in attenuated nicotine-induced NE release. Cytisine or 3-pyr-Cyt alone induced a modest rise in tyrosine hydroxylase (TH) mRNA levels (index of the cell's catecholamine biosynthetic capacity). We conclude that both, cytisine and 3-pyr-Cyt (i) display typical partial agonist properties at naturally existing ganglionic nAChR (α3β4 and α7 nAChR) with regard to catecholamine homeostasis (i.e. NE release and re-synthesis) and (ii) modulated the effect of nicotine during combined treatment. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  19. Enhanced nicotinic receptor mediated relaxations in gastroesophageal muscle fibers from Barrett's esophagus patients.

    Science.gov (United States)

    Miller, L S; Vegesna, A K; Braverman, A S; Barbe, M F; Ruggieri, M R

    2014-03-01

    Increased nicotinic receptor mediated relaxation in the gastroesophageal antireflux barrier may be involved in the pathophysiology of reflux. This study is designed to determine whether the defects we previously identified in gastroesophageal reflux disease patients in- vivo are due to abnormalities of the gastric sling, gastric clasp, or lower esophageal circular (LEC) muscle fibers. Muscle strips from whole stomachs and esophagi were obtained from 16 normal donors and 15 donors with histologically proven Barrett's esophagus. Contractile and relaxant responses of gastric sling, gastric clasp, or LEC fibers were determined to increasing concentrations of carbachol and to nicotine after inducing maximal contraction to bethanechol. Muscarinic receptor density was measured using subtype selective immunoprecipitation. Barrett's esophagus gastric sling and LEC fibers have decreased carbachol-induced contractions. Barrett's esophagus sling fibers have decreased M2 -muscarinic receptors and LEC fibers have decreased M3 receptors. Relaxations of all three fiber types are greater in Barrett's esophagus specimens to both high carbachol concentrations and to nicotine following bethanechol precontraction. The maximal response to bethanechol is greater in Barrett esophagus sling and LEC fibers. The increased contractile response to bethanechol in Barrett's specimens indicates that the defect is likely not due to the smooth muscle itself. The enhanced nicotinic receptor mediated response may be involved in greater relaxation of the muscles within the high-pressure zone of the gastroesophageal junction during transient lower esophageal sphincter relaxations and during deglutitive inhibition and may be involved in the pathophysiology of gastroesophageal reflux disease. © 2013 John Wiley & Sons Ltd.

  20. Nicotine increases GABAergic input on rat dorsal raphe serotonergic neurons through alpha7 nicotinic acetylcholine receptor.

    Science.gov (United States)

    Hernández-Vázquez, F; Chavarría, K; Garduño, J; Hernández-López, S; Mihailescu, S P

    2014-12-15

    The dorsal raphe nucleus (DRN) contains large populations of serotonergic (5-HT) neurons. This nucleus receives GABAergic inhibitory afferents from many brain areas and from DRN interneurons. Both GABAergic and 5-HT DRN neurons express functional nicotinic acetylcholine receptors (nAChRs). Previous studies have demonstrated that nicotine increases 5-HT release and 5-HT DRN neuron discharge rate by stimulating postsynaptic nAChRs and by increasing glutamate and norepinephrine release inside DRN. However, the influence of nicotine on the GABAergic input to 5-HT DRN neurons was poorly investigated. Therefore, the aim of this work was to determine the effect of nicotine on GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of 5-HT DRN neurons and the subtype of nAChR(s) involved in this response. Experiments were performed in coronal slices obtained from young Wistar rats. GABAergic sIPSCs were recorded from post hoc-identified 5-HT DRN neurons with the whole cell voltage patch-clamp technique. Administration of nicotine (1 μM) increased sIPSC frequency in 72% of identified 5-HT DRN neurons. This effect was not reproduced by the α4β2 nAChR agonist RJR-2403 and was not influenced by TTX (1 μM). It was mimicked by the selective agonist for α7 nAChR, PNU-282987, and exacerbated by the positive allosteric modulator of the same receptor, PNU-120596. The nicotine-induced increase in sIPSC frequency was independent on voltage-gated calcium channels and dependent on Ca(2+)-induced Ca(2+) release (CICR). These results demonstrate that nicotine increases the GABAergic input to most 5-HT DRN neurons, by activating α7 nAChRs and producing CICR in DRN GABAergic terminals. Copyright © 2014 the American Physiological Society.

  1. Targeting nicotinic acetylcholine receptor to treat smoking-related periodontitis.

    Science.gov (United States)

    Liu, Ying-Feng; Ge, Xin; Wen, Ling-Ying; Wang, Xiao-Jing

    2011-02-01

    Tobacco smoking is considered to be one of the major risk factors for periodontitis. Nicotine, the major component in tobacco smoke, has been considered playing an important role in tobacco-related morbidity by acting through the nicotinic acetylcholine receptors (nAChRs) expressed by non-neuronal cells. Recently studies found that nAChRs could be expressed on oral gingival and periodontal tissues. We hypothesize that nicotine may act on periodontal tissues directly and specifically through nAChRs to affect periodontitis activity, and that nicotine-induced periodontitis could be prevented by tissue-selective nAChR inhibitors targeting periodontal nAChRs. Thus, periodontal nAChRs may provide to be novel molecular targets to treat smoking-related periodontitis, effectively blocking of periodontal nAChRs may offer an optimistic outlook for the therapy of smoking- related periodontitis. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Nicotine Accelerates Atherosclerosis in Apolipoprotein E-Deficient Mice by Activating α7 Nicotinic Acetylcholine Receptor on Mast Cells.

    Science.gov (United States)

    Wang, Chen; Chen, Han; Zhu, Wei; Xu, Yinchuan; Liu, Mingfei; Zhu, Lianlian; Yang, Fan; Zhang, Ling; Liu, Xianbao; Zhong, Zhiwei; Zhao, Jing; Jiang, Jun; Xiang, Meixiang; Yu, Hong; Hu, Xinyang; Lu, Hong; Wang, Jian'an

    2017-01-01

    Cigarette smoking is an independent risk factor for atherosclerosis. Nicotine, the addictive component of cigarettes, induces mast cell (MC) release and contributes to atherogenesis. The purpose of this study was to determine whether nicotine accelerates atherosclerosis through MC-mediated mechanisms and whether MC stabilizer prevents this pathological process. Nicotine administration increased the size of atherosclerotic lesions in apolipoprotein E-deficient (Apoe-/-) mice fed a fat-enriched diet. This was accompanied by enhanced intraplaque macrophage content and lipid deposition but reduced collagen and smooth muscle cell contents. MC deficiency in Apoe-/- mice (Apoe-/-KitW-sh/W-sh) diminished nicotine-induced atherosclerosis. Nicotine activated bone marrow-derived MCs in vitro, which was inhibited by a MC stabilizer disodium cromoglycate or a nonselective nicotinic acetylcholine receptor blocker mecamylamine. Further investigation revealed that α7 nicotinic acetylcholine receptor was a target for nicotine activation in MCs. Nicotine did not change atherosclerotic lesion size of Apoe-/-KitW-sh/W-sh mice reconstituted with MCs from Apoe-/-α7nAChR-/- animals. Activation of α7 nicotinic acetylcholine receptor on MCs is a mechanism by which nicotine enhances atherosclerosis. © 2016 American Heart Association, Inc.

  3. Nicotine stimulates secretion of corticosterone via both CRH and AVP receptors.

    Science.gov (United States)

    Lutfy, Kabirullah; Aimiuwu, Otaren; Mangubat, Michael; Shin, Chang-Sung; Nerio, Namiko; Gomez, Richard; Liu, Yanjun; Friedman, Theodore C

    2012-03-01

    Corticosterone-releasing hormone (CRH) and arginine vasopressin (AVP) are crucial components of the hypothalamic-pituitary-adrenal axis that stimulates the release of adrenocorticotropic hormone from the pituitary and mediate the stress response. CRH binds to two subtypes of CRH receptors (CRH-R1 and CRH-R2) that are present in both central and peripheral tissues. We used the CRH-R1-specific antagonist, antalarmin (ANT), the CRH-R1 and CRH-R2 peptide antagonist, astressin (AST), and the CRH-R2-specific peptide antagonist, astressin2b (AST2b), to determine which CRH receptor is involved in the nicotine-stimulated secretion of corticosterone. Male C57BL/6 mice were administered ANT (20 mg/kg, i.p.), AST (0.3 mg/kg, i.p.), AST2b (0.3 mg/kg, i.p.) or vehicle prior to administration of nicotine (1.0 mg/kg, s.c.), CRH (10 μg/kg, s.c.), AVP (10 μg/kg, s.c.) or saline (s.c.), killed 15 min later and trunk blood collected and assayed for corticosterone plasma levels. We found that CRH enhanced corticosterone release, and this response was blocked by both AST and ANT. Nicotine also increased corticosterone secretion, but this effect persisted in the presence of either CRH antagonist. Furthermore, AST but not ANT or AST2b decreased corticosterone levels associated with stress of handling and injection. We also assessed the role of AVP V(1b) -specific receptor antagonist, SSR149415 alone and in combination with AST and AST2b. Although the AVP antagonist did not alter basal or nicotine-stimulated corticosterone secretion, it attenuated the AVP-induced stimulation of corticosterone and its combination with AST but not AST2b completely abolished nicotine-mediated stimulation of corticosterone secretion. Our results demonstrate that the nicotine-induced stimulation of the hypothalamic-pituitary-adrenal axis is mediated by both the CRH-R and the AVP V(1b) receptor and when the CRH receptor is blocked, nicotine may utilize the AVP V(1b) receptor to mediate secretion of

  4. Quantitative analysis of expression level of estrogen and progesterone receptors and VEGF genes in human endometrial stromal cells after treatment with nicotine.

    Science.gov (United States)

    Totonchi, Hamidreza; Miladpour, Behnoosh; Mostafavi-Pour, Zohreh; Khademi, Fatemeh; Kasraeian, Maryam; Zal, Fatemeh

    2016-10-01

    Cigarette smoke is a complex mixture of toxic chemicals, including nicotine, carbon monoxide, and several recognized carcinogens and mutagens. Nicotine has a direct disturbing influence on steroid hormones (estrogen and progesterone), which are essential components of the female reproductive system, but the effect of nicotine on the hormone receptors is not yet clear. The aim of this study was to elucidate the effect of nicotine on the expression of estrogen receptor (ER), progesterone receptor (PR), and vascular endothelial growth factor (VEGF) in endometrial stromal cells. Expression levels of PR, ER, and VEGF in human endometrial stromal primary cells treated with nicotine (0, 10 -11 , 10 -8 , and 10 -6  μM) for 24 h were measured by quantitative real-time PCR. MTT assay demonstrated that nicotine decreased cell viability in a dose-dependent manner. Real-time PCR data showed that despite decrease in ER expression in the nicotine-treated groups compared with the control, nicotine exerted an increased inhibitory effect on PR expression compared to that on ER expression. VEGF mRNA expression in nicotine-treated endometrial stromal cells was increased. The results from this study provide novel evidence for inhibitory effects of nicotine on steroid hormones receptor expression in human primary endometrial cells. Also, our data suggest that nicotine might have angiogenesis effects on these cells.

  5. Nicotine anxiogenic and rewarding effects are decreased in mice lacking β-endorphin

    Science.gov (United States)

    Trigo, José M.; Zimmer, Andreas; Maldonado, Rafael

    2009-01-01

    The endogenous opioid system plays an important role in the behavioral effects of nicotine. Thus, μ-opioid receptor and the endogenous opioids derived from proenkephalin are involved in the central effects of nicotine. However, the role played by the different endogenous opioid peptides in the acute and chronic effects of nicotine remains to be fully established. Mice lacking β-endorphin were acutely injected with nicotine at different doses to evaluate locomotor, anxiogenic and antinociceptive responses. The rewarding properties of nicotine were evaluated by using the conditioned place-preference paradigm. Mice chronically treated with nicotine were acutely injected with mecamylamine to study the behavioral expression of nicotine withdrawal. Mice lacking β-endorphin exhibited a spontaneous hypoalgesia and hyperlocomotion and a reduction on the anxiogenic and rewarding effects induced by nicotine. Nicotine induced similar antinociception and hypolocomotion in both genotypes and no differences were found in the development of physical dependence. The dissociation between nicotine rewarding properties and physical dependence suggests a differential implication of β-endorphin in these addictive related responses. PMID:19376143

  6. Insect nicotinic acetylcholine receptors (nAChRs): Important amino ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-29

    Dec 29, 2008 ... neonicotinoid insecticides affinity remarkably, but showed little effects on insect nAChRs normal function. Key words: Nicotinic acetylcholine receptor, neonicotinoid insecticides, selectivity, resistance. INTRODUCTION. Most commercially important insecticides are neurotoxins that act on ion channels, ...

  7. Chronic FAAH inhibition during nicotine abstinence alters habenular CB1 receptor activity and precipitates depressive-like behaviors.

    Science.gov (United States)

    Simonnet, A; Zamberletti, E; Cador, M; Rubino, T; Caillé, S

    2017-02-01

    The role of the endocannabinoid system in nicotine addiction is being increasingly acknowledged. Acute inhibition of anandamide (AEA) degradation efficiently reduces nicotine withdrawal-induced affective symptoms in rats and fatty acid amide hydrolase (FAAH), the degradation enzyme of AEA, has been proposed as a possible treatment against nicotine addiction. However, it is unclear whether chronic inhibition of AEA during nicotine abstinence will have beneficial or deleterious affective side-effects. Using a rat model of nicotine addiction, we found that, during abstinence, rats injected daily with a FAAH inhibitor (URB597) developed a depressive-like phenotype. Our results show that in the nicotine abstinent rats, URB597 induced low saccharin consumption, persistent immobility in the forced swim test and increased corticosterone levels in response to stress. In addition, URB597decreased CB1 receptor binding and activity in the habenula, a key structure in the control of nicotine-related emotional states. In contrast, non-treated abstinent rats showed increased CB1 receptor activity and behaviors comparable to controls. No FAAH inhibition-induced alterations were observed in animals that had a previous history of saline self-administration. Taken together, our results suggest that chronic FAAH inhibition prevents the homeostatic adaptations of habenular CB1 receptor function that are necessary for the recovery from nicotine dependence. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. In vivo PET imaging of brain nicotinic cholinergic receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bottlaender, M.; Valette, H.; Saba, W.; Schollhorn-Peyronneau, M.A.; Dolle, F.; Syrota, A. [Service Hospitalier Frederic Joliot (CEA/DSV/DRM), 91 - Orsay (France)

    2006-07-01

    Neuronal acetylcholine receptors (nAChRs) are widely distributed throughout the central nervous system where they modulate a number of CNS functions including neurotransmitter release, cognitive function, anxiety, analgesia and control of cerebral blood flow. In the brain, a major subtype is composed of the {alpha}4{beta}2 subunit combination. Density of this subtype has been shown to be decreased in patients with neuro-degenerative disease such as Alzheimer and Parkinson's disease (AD and PD), and mutated receptors has been described in some familial epilepsy. Thus, in vivo mapping of the nicotinic nAChRs by Positron Emission Tomography (PET) are of great interest to monitor the evolution of these pathologies and changes in the neuronal biochemistry induced by therapeutic agents. Recently, a new compound, 3-[2(S)-2-azetidinyl-methoxy]pyridine (A-85380) has been synthesised and labelled with fluorine-18, [{sup 18}F]fluoro-A-85380 (Dolle et al., 1999). The [{sup 18}F]fluoro-A-85380 has been shown to bind with high affinity t o nAChRs in vitro (Saba et al., 2004), and its toxicity was low and compatible with it s use at tracer dose in human PET studies (Valette, 2002). PET studies in baboons showed that, after in vivo administration of [ {sup 18}F]fluoro-A-85380 at a tracer dose, the distribution of the radioactivity in the brain reflect the distribution of the < 4R2 nAChRs. Competition and pre-blocking studies, using nicotinic agonists, confirm that the radiotracer binds specifically to the heteromeric nAChRs in the brain (Valette et al., 1999). The in vivo, characteristics of the [{sup 18}F]fluoro-A-8538 0 combined with its low toxicity make possible the imaging of the nicotinic receptor s in human by PET (Bottlaender 2003). Studies were performed in healthy non-smoker volunteers to evaluate the brain kinetics of [{sup 18}F]fluoro-A-85380 and to assess the quantification of its nAChRs binding in the human brain with PET (Gallezot et a., 2005). The [{sup 18}F

  9. Activation of Peripheral κ-Opioid Receptors Normalizes Caffeine Effects Modified in Nicotine-Dependent Rats during Nicotine Withdrawal.

    Science.gov (United States)

    Sudakov, S K; Bogdanova, N G

    2016-10-01

    The study examined the effect of peripheral (intragastric) ICI-204,448, an agonist of gastric κ-opioid receptors, on the psychostimulating and anxiolytic effects of caffeine in nicotinedependent rats at the stage of nicotine withdrawal. In these rats, the effects of caffeine (10 mg/kg) were perverted. In nicotine-dependent rats, caffeine produced an anxiolytic effect accompanied by pronounced stimulation of motor activity, in contrast to anxiogenic effect induced by caffeine in intact rats without nicotine dependence. During nicotine withdrawal, nicotine-dependent rats demonstrated enhanced sensitivity to nicotine. Intragastric administration of κ-opioid receptor agonist ICI-204,448 normalized the effect of caffeine in nicotinedependent rats. We have previously demonstrated that activation of peripheral κ-opioid receptors inhibited central κ-opioid activity and eliminated manifestations of nicotine withdrawal syndrome in nicotine-dependent rats, e.g. metabolism activation, stimulation of motor activity, and enhancement of food consumption. In its turn, inhibition of central κ-opioid structures activates the brain adenosine system, which can attenuate the caffeine-induced effects in nicotine-dependent rats.

  10. CB1 Cannabinoid Receptors Mediate Cognitive Deficits and Structural Plasticity Changes During Nicotine Withdrawal.

    Science.gov (United States)

    Saravia, Rocio; Flores, África; Plaza-Zabala, Ainhoa; Busquets-Garcia, Arnau; Pastor, Antoni; de la Torre, Rafael; Di Marzo, Vincenzo; Marsicano, Giovanni; Ozaita, Andrés; Maldonado, Rafael; Berrendero, Fernando

    2017-04-01

    Tobacco withdrawal is associated with deficits in cognitive function, including attention, working memory, and episodic memory. Understanding the neurobiological mechanisms involved in these effects is crucial because cognitive deficits during nicotine withdrawal may predict relapse in humans. We investigated in mice the role of CB1 cannabinoid receptors (CB1Rs) in memory impairment and spine density changes induced by nicotine withdrawal precipitated by the nicotinic antagonist mecamylamine. Drugs acting on the endocannabinoid system and genetically modified mice were used. Memory impairment during nicotine withdrawal was blocked by the CB1R antagonist rimonabant or the genetic deletion of CB1R in forebrain gamma-aminobutyric acidergic (GABAergic) neurons (GABA-CB1R). An increase of 2-arachidonoylglycerol (2-AG), but not anandamide, was observed during nicotine withdrawal. The selective inhibitor of 2-AG biosynthesis O7460 abolished cognitive deficits of nicotine abstinence, whereas the inhibitor of 2-AG enzymatic degradation JZL184 did not produce any effect in cognitive impairment. Moreover, memory impairment was prevented by the selective mammalian target of rapamycin inhibitor temsirolimus and the protein synthesis inhibitor anisomycin. Mature dendritic spines on CA1 pyramidal hippocampal neurons decreased 4 days after the precipitation of nicotine withdrawal, when the cognitive deficits were still present. Indeed, a correlation between memory performance and mature spine density was found. Interestingly, these structural plasticity alterations were normalized in GABA-CB1R conditional knockout mice and after subchronic treatment with rimonabant. These findings underline the interest of CB1R as a target to improve cognitive performance during early nicotine withdrawal. Cognitive deficits in early abstinence are associated with increased relapse risk. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  11. Neuronal Nicotinic Acetylcholine Receptors: Neuroplastic Changes underlying Alcohol and Nicotine Addictions

    Directory of Open Access Journals (Sweden)

    Allison Anne Feduccia

    2012-08-01

    Full Text Available Addictive drugs can activate systems involved in normal reward-related learning, creating long-lasting memories of the drug’s reinforcing effects and the environmental cues surrounding the experience. These memories significantly contribute to the maintenance of compulsive drug use as well as cue-induced relapse which can occur even after long periods of abstinence. Synaptic plasticity is thought to be a prominent molecular mechanism underlying drug-induced learning and memories. Ethanol and nicotine are both widely abused drugs that share a common molecular target in the brain, the neuronal nicotinic acetylcholine receptors (nAChRs. The nAChRs are ligand-gated ion channels that are vastly distributed throughout the brain and play a key role in synaptic neurotransmission. In this review, we will delineate the role of nAChRs in the development of ethanol and nicotine addiction. We will characterize both ethanol and nicotine’s effects on nAChR-mediated synaptic transmission and plasticity in several key brain areas that are important for addiction. Finally, we will discuss some of the behavioral outcomes of drug-induced synaptic plasticity in animal models. An understanding of the molecular and cellular changes that occur following administration of ethanol and nicotine will lead to better therapeutic strategies.

  12. A Multi-Route Model of Nicotine-Cotinine Pharmacokinetics, Pharmacodynamics and Brain Nicotinic Acetylcholine Receptor Binding in Humans

    Energy Technology Data Exchange (ETDEWEB)

    Teeguarden, Justin G.; Housand, Conrad; Smith, Jordan N.; Hinderliter, Paul M.; Gunawan, Rudy; Timchalk, Charles

    2013-02-01

    The pharmacokinetics of nicotine, the pharmacologically active alkaloid in tobacco responsible for addiction, are well characterized in humans. We developed a physiologically based pharmacokinetic/pharmacodynamic model of nicotine pharmacokinetics, brain dosimetry and brain nicotinic acetylcholine receptor (nAChRs) occupancy. A Bayesian framework was applied to optimize model parameters against multiple human data sets. The resulting model was consistent with both calibration and test data sets, but in general underestimated variability. A pharmacodynamic model relating nicotine levels to increases in heart rate as a proxy for the pharmacological effects of nicotine accurately described the nicotine related changes in heart rate and the development and decay of tolerance to nicotine. The PBPK model was utilized to quantitatively capture the combined impact of variation in physiological and metabolic parameters, nicotine availability and smoking compensation on the change in number of cigarettes smoked and toxicant exposure in a population of 10,000 people presented with a reduced toxicant (50%), reduced nicotine (50%) cigarette Across the population, toxicant exposure is reduced in some but not all smokers. Reductions are not in proportion to reductions in toxicant yields, largely due to partial compensation in response to reduced nicotine yields. This framework can be used as a key element of a dosimetry-driven risk assessment strategy for cigarette smoke constituents.

  13. In vivo interactions between α7 nicotinic acetylcholine receptor and nuclear peroxisome proliferator-activated receptor-α: Implication for nicotine dependence.

    Science.gov (United States)

    Jackson, Asti; Bagdas, Deniz; Muldoon, Pretal P; Lichtman, Aron H; Carroll, F Ivy; Greenwald, Mark; Miles, Michael F; Damaj, M Imad

    2017-05-15

    Chronic tobacco use dramatically increases health burdens and financial costs. Limitations of current smoking cessation therapies indicate the need for improved molecular targets. The main addictive component of tobacco, nicotine, exerts its dependency effects via nicotinic acetylcholine receptors (nAChRs). Activation of the homomeric α7 nAChR reduces nicotine's rewarding properties in conditioned place preference (CPP) test and i.v. self-administration models, but the mechanism underlying these effects is unknown. Recently, the nuclear receptor peroxisome proliferator-activated receptor type-α (PPARα) has been implicated as a downstream signaling target of the α7 nAChR in ventral tegmental area dopamine cells. The present study investigated PPARα as a possible mediator of the effect of α7 nAChR activation in nicotine dependence. Our results demonstrate the PPARα antagonist GW6471 blocks actions of the α7 nAChR agonist PNU282987 on nicotine reward in an unbiased CPP test in male ICR adult mice. These findings suggests that α7 nAChR activation attenuates nicotine CPP in a PPARα-dependent manner. To evaluate PPARα activation in nicotine dependence we used the selective and potent PPARα agonist, WY-14643 and the clinically used PPARα activator, fenofibrate, in nicotine CPP and we observed attenuation of nicotine preference, but fenofibrate was less potent. We also studied PPARα in nicotine dependence by evaluating its activation in nicotine withdrawal. WY-14643 reversed nicotine withdrawal signs whereas fenofibrate had modest efficacy. This suggests that PPARα plays a role in nicotine reward and withdrawal and that further studies are warranted to elucidate its function in mediating the effects of α7 nAChRs in nicotine dependence. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Neuronal nicotinic receptor agonists improve gait and balance in olivocerebellar ataxia.

    Science.gov (United States)

    Wecker, L; Engberg, M E; Philpot, R M; Lambert, C S; Kang, C W; Antilla, J C; Bickford, P C; Hudson, C E; Zesiewicz, T A; Rowell, Peter P

    2013-10-01

    Clinical studies have reported that the nicotinic receptor agonist varenicline improves balance and coordination in patients with several types of ataxia, but confirmation in an animal model has not been demonstrated. This study investigated whether varenicline and nicotine could attenuate the ataxia induced in rats following destruction of the olivocerebellar pathway by the neurotoxin 3-acetylpyridine (3-AP). The administration of 3-AP (70 mg/kg followed by 300 mg niacinamide/kg; i.p.) led to an 85% loss of inferior olivary neurons within one week without evidence of recovery, and was accompanied by a 72% decrease in rotorod activity, a 3-fold increase in the time to traverse a stationary beam, a 19% decrease in velocity and 31% decrease in distance moved in the open field, and alterations in gait parameters, with a 19% increase in hindpaw stride width. The daily administration of nicotine (0.33 mg free base/kg) for one week improved rotorod performance by 50% and normalized the increased hindpaw stride width, effects that were prevented by the daily preadministration of the nicotinic antagonist mecamylamine (0.8 mg free base/kg). Varenicline (1 and 3 mg free base/kg daily) also improved rotorod performance by approximately 50% following one week of administration, and although it did not alter the time to traverse the beam, it did improve the ability to maintain balance on the beam. Neither varenicline nor nicotine, at doses that improved balance, affected impaired locomotor activity in the open field. Results provide evidence that nicotinic agonists are of benefit for alleviating some of the behavioral deficits in olivocerebellar ataxia and warrant further studies to elucidate the specific mechanism(s) involved. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. The α7 nicotinic acetylcholine receptor complex

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Mikkelsen, Jens D

    2012-01-01

    of such compounds in vivo is highly dependent on α7 nAChR-interacting proteins, such as RIC-3 and lynx1, which modulate expression and function of the receptor. These regulatory proteins are often not expressed in in vitro models used to study α7 nAChR function, and it is not known to what extent they are involved...

  16. Structural model of nicotinic acetylcholine receptor isotypes bound to acetylcholine and nicotine

    Directory of Open Access Journals (Sweden)

    Abagyan Ruben

    2002-01-01

    Full Text Available Abstract Background Nicotine is a psychoactive drug presenting a diverse array of biological activities, some positive, such as enhancement of cognitive performances, others negative, such as addiction liability. Ligands that discriminate between the different isotypes of nicotinic acetylcholine receptors (nAChRs could present improved pharmacology and toxicity profile. Results Based on the recent crystal structure of a soluble acetylcholine binding protein from snails, we have built atomic models of acetylcholine and nicotine bound to the pocket of four different human nAChR subtypes. The structures of the docked ligands correlate with available biochemical data, and reveal that the determinants for isotype selectivity are relying essentially on four residues, providing diversity of the ligand binding pocket both in terms of Van der Waals boundary, and electrostatic potential. We used our models to screen in silico a large compound database and identify a new ligand candidate that could display subtype selectivity. Conclusion The nAChR-agonist models should be useful for the design of nAChR agonists with diverse specificity profiles.

  17. Structural Studies of Nicotinic Acetylcholine Receptors

    DEFF Research Database (Denmark)

    Shahsavar, Azadeh; Gajhede, Michael; Kastrup, Jette

    2016-01-01

    -resolution structure of a nAChR is yet to be determined, structural studies are to a large extent based on acetylcholine binding proteins (AChBPs) that despite low overall sequence identity display high degree of conservation of overall structure and amino acids at the ligand-binding site. Further, AChBPs reproduce...... relative binding affinities of ligands at nAChRs. Over the past decade, AChBPs have been used extensively as models for nAChRs and have aided the understanding of drug receptor interactions at nAChRs significantly. This article is protected by copyright. All rights reserved....

  18. Effects of alpha-7 nicotinic acetylcholine receptor positive allosteric modulator on lipopolysaccharide-induced neuroinflammatory pain in mice.

    Science.gov (United States)

    Abbas, Muzaffar; Rahman, Shafiqur

    2016-07-15

    Evidence indicates that microglial activation contributes to the pathophysiology and maintenance of neuroinflammatory pain involving central nervous system alpha-7 nicotinic acetylcholine receptors. The objective of the present study was to determine the effects of 3a,4,5,9b-Tetrahydro-4-(1-naphthalenyl)-3H-cyclopentan[c]quinoline-8-sulfonamide (TQS), an alpha-7 nicotinic acetylcholine receptor positive allosteric modulator (PAM), on tactile allodynia and thermal hyperalgesia following lipopolysaccharide (LPS)-induced microglial activation in hippocampus, a neuroinflammatory pain model in mice. In addition, we examined the effects of TQS on microglial activation marker, an ionized calcium-binding adapter molecule 1 (Iba-1), in the hippocampus may be associated with neuroinflammatory pain. Pretreatment of TQS (4mg/kg) significantly reduced LPS (1mg/kg)-induced tactile allodynia and thermal hyperalgesia. Moreover, pretreatment of methyllycaconitine (3mg/kg) significantly reversed TQS-induced antiallodynic and antihyperalgesic responses indicating the involvement of alpha-7 nicotinic acetylcholine receptor. Pretreatment of TQS significantly decreased LPS-induced increased in hippocampal Iba-1 expression. Overall, these results suggest that TQS reduces LPS-induced neuroinflammatory pain like symptoms via modulating microglial activation likely in the hippocampus and/or other brain region by targeting alpha-7 nicotinic acetylcholine receptor. Therefore, alpha-7 nicotinic acetylcholine receptor PAM such as TQS could be a potential drug candidate for the treatment of neuroinflammatory pain. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Nicotine-Induced Effects on Nicotinic Acetylcholine Receptors (nAChRs), Ca2+ and Brain-Derived Neurotrophic Factor (BDNF) in STC-1 Cells.

    Science.gov (United States)

    Qian, Jie; Mummalaneni, Shobha K; Alkahtani, Reem M; Mahavadi, Sunila; Murthy, Karnam S; Grider, John R; Lyall, Vijay

    2016-01-01

    In addition to the T2R bitter taste receptors, neuronal nicotinic acetylcholine receptors (nAChRs) have recently been shown to be involved in the bitter taste transduction of nicotine, acetylcholine and ethanol. However, at present it is not clear if nAChRs are expressed in enteroendocrine cells other than beta cells of the pancreas and enterochromaffin cells, and if they play a role in the synthesis and release of neurohumoral peptides. Accordingly, we investigated the expression and functional role of nAChRs in enteroendocrine STC-1 cells. Our studies using RT-PCR, qRT-PCR, immunohistochemical and Western blotting techniques demonstrate that STC-1 cells express several α and β nAChR subunits. Exposing STC-1 cells to nicotine acutely (24h) or chronically (4 days) induced a differential increase in the expression of nAChR subunit mRNA and protein in a dose- and time-dependent fashion. Mecamylamine, a non-selective antagonist of nAChRs, inhibited the nicotine-induced increase in mRNA expression of nAChRs. Exposing STC-1 cells to nicotine increased intracellular Ca2+ in a dose-dependent manner that was inhibited in the presence of mecamylamine or dihydro-β-erythroidine, a α4β2 nAChR antagonist. Brain-derived neurotrophic factor (BDNF) mRNA and protein were detected in STC-1 cells using RT-PCR, specific BDNF antibody, and enzyme-linked immunosorbent assay. Acute nicotine exposure (30 min) decreased the cellular content of BDNF in STC-1 cells. The nicotine-induced decrease in BDNF was inhibited in the presence of mecamylamine. We also detected α3 and β4 mRNA in intestinal mucosal cells and α3 protein expression in intestinal enteroendocrine cells. We conclude that STC-1 cells and intestinal enteroendocrine cells express nAChRs. In STC-1 cells nAChR expression is modulated by exposure to nicotine in a dose- and time-dependent manner. Nicotine interacts with nAChRs and inhibits BDNF expression in STC-1 cells.

  20. Development of fetal nicotine and muscarinic receptors in utero

    Directory of Open Access Journals (Sweden)

    C. Mao

    2007-05-01

    Full Text Available The role of acetylcholine in the central and peripheral nervous systems is well established in adults. Cholinergic modulation of vascular functions and body fluid balance has been extensively studied. In the embryo-fetus, cholinergic receptors are widespread in the peripheral and central systems, including smooth muscle and the epithelial lining of the cardiovascular, digestive, and urinary systems, as well as in the brain. Fetal nicotine and muscarinic receptors develop in a pattern (e.g., amount and distribution related to gestational periods. Cholinergic mechanisms have been found to be relatively intact and functional in the control of vascular homeostasis during fetal life in utero at least during the last third of gestation. This review focuses on the development of fetal nicotine and muscarinic receptors, and provides information indicating that central cholinergic systems are well developed in the control of fetal blood pressure and body fluid balance before birth. Therefore, the development of cholinergic systems in utero plays an important role in fetal vascular regulation, gastrointestinal motility, and urinary control.

  1. Nicotinic acetylcholine receptors: specific antibodies and functions in humoral immunity

    Directory of Open Access Journals (Sweden)

    M. V. Skok,

    2013-12-01

    Full Text Available Nicotinic acetylcholine receptors (nAChRs are ligand-gated ion channels initially discovered in muscles and neurons and further found in many non-excitable cells. The present review summarizes the results of studies performed in the Department of Molecular Immunology during the last decade and concerning the structure and functions of nAChRs in B lymphocytes and in mitochondria, as well as the role of nAChR-specific antibodies in the develop­ment of neurodegenerative disorders like Alzheimer disease.

  2. Effects of antihistamines on the function of human α7-nicotinic acetylcholine receptors.

    Science.gov (United States)

    Sadek, Bassem; Khanian, Seyedeh Soha; Ashoor, Abrar; Prytkova, Tatiana; Ghattas, Mohammad A; Atatreh, Noor; Nurulain, Syed M; Yang, Keun-Hang Susan; Howarth, Frank Christopher; Oz, Murat

    2015-01-05

    Effects of the histamine H₁ receptor (H1R) antagonists (antihistamines), promethazine (PMZ), orphenadrine (ORP), chlorpheniramine (CLP), pyrilamine (PYR), diphenhydramine (DPH), citerizine (CTZ), and triprolidine (TRP) on the functional properties of the cloned α7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes were investigated. Antihistamines inhibited the α7-nicotinic acetylcholine receptor in the order PYR>CLP>TRP>PMZ>ORP≥DPH≥CTZ. Among the antihistamines, PYR showed the highest reversible inhibition of acetylcholine (100 µM)-induced responses with IC₅₀ of 6.2 µM. PYR-induced inhibition was independent of the membrane potential and could not be reversed by increasing the concentration of acetylcholine. Specific binding of [¹²⁵I] α-bungarotoxin, a selective antagonist for α7-nicotinic acetylcholine receptor, was not changed in the presence of PYR suggesting a non-competitive inhibition of nicotinic receptors. In line with functional experiments, docking studies indicated that PYR can potentially bind allosterically with the α7 transmembrane domain. Our results indicate that the H₂-H₄ receptor antagonists tested in this study (10 µM) showed negligible inhibition of α7-nicotinic acetylcholine receptors. On the other hand, H₁ receptor antagonists inhibited the function of human α7-nicotinic acetylcholine receptor, with varying potencies. These results emphasize the importance of α7-nicotinic acetylcholine receptor for future pharmacological/toxicological profiling. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Possible role of the α7 nicotinic receptors in mediating nicotine's effect on developing lung - implications in unexplained human perinatal death.

    Science.gov (United States)

    Lavezzi, Anna M; Corna, Melissa F; Alfonsi, Graziella; Matturri, Luigi

    2014-02-01

    It is well known that maternal smoking during pregnancy is very harmful to the fetus. Prenatal nicotine absorption, in particular, is associated with alterations in lung development and functions at birth and with respiratory disorders in infancy. Many of the pulmonary disorders are mediated by the interaction of nicotine with the nicotinic receptors (nAChRs), above all with the α7 nAChR subunits that are widely expressed in the developing lung. To determine whether the lung hypoplasia frequently observed in victims of sudden fetal and neonatal death with a smoker mother may result from nicotine interacting with lung nicotinic receptors, we investigated by immunohistochemistry the possible presence of the α7 nAChR subunit overexpression in these pathologies. In lung histological sections from 45 subjects who died of sudden intrauterine unexplained death syndrome (SIUDS) and 15 subjects who died of sudden infant death syndrome (SIDS), we applied the radial alveolar count (RAC) to evaluate the degree of lung maturation, and the immunohistochemical technique for nAChRs, in particular for the α7 nAChR subunit identification. In the same cases, an in-depth study of the autonomic nervous system was performed to highlight possible developmental alterations of the main vital centers located in the brainstem. We diagnosed a "lung hypoplasia", on the basis of RAC values lower than the normal reference values, in 63% of SIUDS/SIDS cases and 8% of controls. In addition, we observed a significantly higher incidence of strong α7 nAChR immunostaining in lung epithelial cells and lung vessel walls in sudden fetal and infant death cases with a smoker mother than in age-matched controls. Hypoplasia of the raphe, the parafacial, the Kölliker-Fuse, the arcuate and the pre-Bötzinger nuclei was at the same time present in the brainstem of these victims. These findings demonstrate that when crossing the placenta, nicotine can interact with nicotinic receptors of both neuronal and

  4. TC299423, a Novel Agonist for Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Teagan R. Wall

    2017-09-01

    Full Text Available (E-5-(Pyrimidin-5-yl-1,2,3,4,7,8-hexahydroazocine (TC299423 is a novel agonist for nicotinic acetylcholine receptors (nAChRs. We examined its efficacy, affinity, and potency for α6β2∗ (α6β2-containing, α4β2∗, and α3β4∗ nAChRs, using [125I]-epibatidine binding, whole-cell patch-clamp recordings, synaptosomal 86Rb+ efflux, [3H]-dopamine release, and [3H]-acetylcholine release. TC299423 displayed an EC50 of 30–60 nM for α6β2∗ nAChRs in patch-clamp recordings and [3H]-dopamine release assays. Its potency for α6β2∗ in these assays was 2.5-fold greater than that for α4β2∗, and much greater than that for α3β4∗-mediated [3H]-acetylcholine release. We observed no major off-target binding on 70 diverse molecular targets. TC299423 was bioavailable after intraperitoneal or oral administration. Locomotor assays, measured with gain-of-function, mutant α6 (α6L9′S nAChR mice, show that TC299423 elicits α6β2∗ nAChR-mediated responses at low doses. Conditioned place preference assays show that low-dose TC299423 also produces significant reward in α6L9′S mice, and modest reward in WT mice, through a mechanism that probably involves α6(non-α4β2∗ nAChRs. However, TC299423 did not suppress nicotine self-administration in rats, indicating that it did not block nicotine reinforcement in the dosage range that was tested. In a hot-plate test, TC299423 evoked antinociceptive responses in mice similar to those of nicotine. TC299423 and nicotine similarly inhibited mouse marble burying as a measure of anxiolytic effects. Taken together, our data suggest that TC299423 will be a useful small-molecule agonist for future in vitro and in vivo studies of nAChR function and physiology.

  5. Nicotinic Acetylcholine Receptors in the Pathophysiology of Alzheimer's Disease

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Andreasen T., Jesper; Arvaniti, Maria

    2016-01-01

    Nicotinic acetylcholine receptors (nAChRs) have been pursued for decades as potential molecular targets to treat cognitive dysfunction in Alzheimer's disease (AD) due to their positioning within regions of the brain critical in learning and memory, such as the prefrontal cortex and hippocampus......, and their demonstrated role in processes underlying cognition such as synaptic facilitation, and theta and gamma wave activity. Historically, activity at these receptors is facilitated in AD by use of drugs that increase the levels of their endogenous agonist acetylcholine, and more recently nAChR selective ligands have...... interactions to modify nAChR function adds a new level of complexity to cholinergic signaling in the brain that may be specifically altered in AD. It is currently not known to what degree current nAChR ligands affect these interactions, and it is possible that the difference in the clinical effect of n...

  6. Nicotine decreases attentional bias to negative-affect-related Stroop words among smokers.

    Science.gov (United States)

    Rzetelny, Adam; Gilbert, David G; Hammersley, Jonathan; Radtke, Robert; Rabinovich, Norka E; Small, Stacey L

    2008-06-01

    The present study examined the hypothesis that nicotine is associated with reduced attentional bias to affective and smoking-related stimuli in a modified Stroop task. A total of 56 habitual smokers were each tested on 4 days with 14 mg nicotine patches and placebo patches, counterbalanced, as a within-subjects factor in a double-blind design. A modified Stroop using negative-affect words, smoking words, color words, and neutral words was presented via computer in blocked format. As predicted, nicotine, relative to placebo, was associated with decreased attentional bias to negative words. Nicotine speeded performance during smoking-word and color-word blocks to the same degree as during neutral words and thus appeared to also have a nonspecific performance-enhancing effect. In an exploratory analysis, nicotine-attention effects occurred only in the initial presentation of pairs of blocked word pages. Nicotine also was associated with improved mood. The results are discussed in terms of affect-attention and smoking literatures.

  7. ICV STZ induced impairment in memory and neuronal mitochondrial function: A protective role of nicotinic receptor.

    Science.gov (United States)

    Saxena, Gunjan; Patro, Ishan K; Nath, Chandishwar

    2011-10-10

    The present study was planned to evaluate the cholinergic influence on mitochondrial activity and neurodegeneration associated with impaired memory in intracerebroventricular (ICV) streptozotocin (STZ) treated rats. STZ (3mg/kg), administered ICV twice with an interval of 48h between the two doses, showed significant impairment in spatial memory tested by water maze test 14 days after first dose without altering blood glucose level and locomotor activity. Animals were sacrificed on 21st day of ICV administration. STZ significantly increased malondialdehyde (MDA), reactive oxygen species (ROS), Ca(2+) ion influx, caspase-3 activity and decreased glutathione (GSH) level. Acetylcholinesterase inhibitors tacrine and donepezil (5mg/kg, PO) pretreatment significantly prevented STZ induced memory deficit, oxidative stress, Ca(2+) influx and caspase-3 activity. Carbachol, a muscarinic cholinergic agonist (0.01mg/kg, SC) did not show any significant effect on ROS generation, Ca(2+) ion influx and caspase-3 activity. While nicotinic cholinergic agonist, nicotine, significantly attenuated ICV STZ induced mitochondrial dysfunction and caspase-3 activity. The results indicate that instead of muscarinic receptors nicotinic receptors may be involved in neuroprotection by maintaining mitochondrial functions. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Menthol Enhances the Desensitization of Human α3β4 Nicotinic Acetylcholine Receptors.

    Science.gov (United States)

    Ton, Hoai T; Smart, Amanda E; Aguilar, Brittany L; Olson, Thao T; Kellar, Kenneth J; Ahern, Gerard P

    2015-08-01

    The α3β4 nicotinic acetylcholine receptor (nAChR) subtype is widely expressed in the peripheral and central nervous systems, including in airway sensory nerves. The nAChR subtype transduces the irritant effects of nicotine in tobacco smoke and, in certain brain areas, may be involved in nicotine addiction and/or withdrawal. Menthol, a widely used additive in cigarettes, is a potential analgesic and/or counterirritant at sensory nerves and may also influence nicotine's actions in the brain. We examined menthol's effects on recombinant human α3β4 nAChRs and native nAChRs in mouse sensory neurons. Menthol markedly decreased nAChR activity as assessed by Ca(2+) imaging, (86)Rb(+) efflux, and voltage-clamp measurements. Coapplication of menthol with acetylcholine or nicotine increased desensitization, demonstrated by an increase in the rate and magnitude of the current decay and a reduction of the current integral. These effects increased with agonist concentration. Pretreatment with menthol followed by its washout did not affect agonist-induced desensitization, suggesting that menthol must be present during the application of agonist to augment desensitization. Notably, menthol acted in a voltage-independent manner and reduced the mean open time of single channels without affecting their conductance, arguing against a simple channel-blocking effect. Further, menthol slowed or prevented the recovery of nAChRs from desensitization, indicating that it probably stabilizes a desensitized state. Moreover, menthol at concentrations up to 1 mM did not compete for the orthosteric nAChR binding site labeled by [(3)H]epibatidine. Taken together, these data indicate that menthol promotes desensitization of α3β4 nAChRs by an allosteric action. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  9. Menthol Binding and Inhibition of α7-Nicotinic Acetylcholine Receptors

    Science.gov (United States)

    Ashoor, Abrar; Nordman, Jacob C.; Veltri, Daniel; Yang, Keun-Hang Susan; Al Kury, Lina; Shuba, Yaroslav; Mahgoub, Mohamed; Howarth, Frank C.; Sadek, Bassem; Shehu, Amarda; Kabbani, Nadine; Oz, Murat

    2013-01-01

    Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α7 subunit of the nicotinic acetylcholine (nACh) receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca2+-dependent Cl− channels, since menthol inhibition remained unchanged by intracellular injection of the Ca2+ chelator BAPTA and perfusion with Ca2+-free bathing solution containing Ba2+. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [125I] α-bungarotoxin was not attenuated by menthol. Studies of α7- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α7 mediated Ca2+ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner. PMID:23935840

  10. Menthol binding and inhibition of α7-nicotinic acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Abrar Ashoor

    Full Text Available Menthol is a common compound in pharmaceutical and commercial products and a popular additive to cigarettes. The molecular targets of menthol remain poorly defined. In this study we show an effect of menthol on the α7 subunit of the nicotinic acetylcholine (nACh receptor function. Using a two-electrode voltage-clamp technique, menthol was found to reversibly inhibit α7-nACh receptors heterologously expressed in Xenopus oocytes. Inhibition by menthol was not dependent on the membrane potential and did not involve endogenous Ca(2+-dependent Cl(- channels, since menthol inhibition remained unchanged by intracellular injection of the Ca(2+ chelator BAPTA and perfusion with Ca(2+-free bathing solution containing Ba(2+. Furthermore, increasing ACh concentrations did not reverse menthol inhibition and the specific binding of [(125I] α-bungarotoxin was not attenuated by menthol. Studies of α7- nACh receptors endogenously expressed in neural cells demonstrate that menthol attenuates α7 mediated Ca(2+ transients in the cell body and neurite. In conclusion, our results suggest that menthol inhibits α7-nACh receptors in a noncompetitive manner.

  11. a2* Nicotinic Acetylcholine Receptors Influence Hippocampus-Dependent Learning and Memory in Adolescent Mice

    Science.gov (United States)

    Lotfipour, Shahrdad; Mojica, Celina; Nakauchi, Sakura; Lipovsek, Marcela; Silverstein, Sarah; Cushman, Jesse; Tirtorahardjo, James; Poulos, Andrew; Elgoyhen, Ana Belén; Sumikawa, Katumi; Fanselow, Michael S.; Boulter, Jim

    2017-01-01

    The absence of a2* nicotinic acetylcholine receptors (nAChRs) in oriens lacunosum moleculare (OLM) GABAergic interneurons ablate the facilitation of nicotine-induced hippocampal CA1 long-term potentiation and impair memory. The current study delineated whether genetic mutations of a2* nAChRs ("Chrna2"[superscript L9'S/L9'S] and…

  12. Nicotinic Acetylcholine Receptor Variants Are Related to Smoking Habits, but Not Directly to COPD

    NARCIS (Netherlands)

    Budulac, Simona E.; Vonk, Judith M.; Postma, Dirkje S.; Siedlinski, Mateusz; Timens, Wim; Boezen, Marike H

    2012-01-01

    Genome-wide association studies identified single nucleotide polymorphisms (SNPs) in the nicotinic acetylcholine receptors (nAChRs) cluster as a risk factor for nicotine dependency and COPD. We investigated whether SNPs in the nAChR cluster are associated with smoking habits and lung function

  13. Alpha5 nicotinic acetylcholine receptor mediates nicotine-induced HIF-1α and VEGF expression in non-small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiaoli; Jia, Yanfei; Zu, Shanshan [Central Laboratory, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013 (China); Li, Ruisheng [Institute of Infectious Diseases, 302 Military Hospital, Beijing 100039 (China); Jia, Ying; Zhao, Yun; Xiao, Dongjie [Central Laboratory, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013 (China); Dang, Ningning [Department of Dermatology, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013 (China); Wang, Yunshan [Central Laboratory, Jinan Central Hospital Affiliated to Shandong University, Jinan 250013 (China)

    2014-07-15

    By binding to nicotinic acetylcholine receptors (nAChRs), nicotine induces the proliferation and apoptosis of non-small cell lung cancer (NSCLC). Previous studies have indicated that α5-nAChR is highly associated with lung cancer risk and nicotine dependence. However, the mechanisms through which α5-nAChRs may influence lung carcinogenesis are far from clear. In the present study, we investigated the roles of α5-nAChR in the nicotine-induced expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF). Immunohistochemistry was used to detect the expression of α5-nAChR and HIF-1α in 60 specimens of lung cancer and para-carcinoma tissue. The correlations between the expression levels of α5-nAChR and HIF-1α and other clinicopathological data were analyzed. In a cell line that highly expressed α5-nAChR, the loss of α5-nAChR function by siRNA was used to study whether α5-nAChR is involved in the nicotine-induced expression of HIF-1α and VEGF through the activation of the ERK1/2 and PI3K/Akt signaling pathways. Cell growth was detected using the cell counting kit-8 (CCK-8). α5-nAChR (78.3%) and HIF-1α (88.3%) were both overexpressed in NSCLC, and their expression levels were found to be correlated with each other (P < 0.05). In the A549 cell line, α5-nAChR and HIF-1α were found to be expressed under normal conditions, and their expression levels were significantly increased in response to nicotine treatment. The silencing of α5-nAChR significantly inhibited the nicotine-induced cell proliferation compared with the control group and attenuated the nicotine-induced upregulation of HIF-1α and VEGF, and these effects required the cooperation of the ERK1/2 and PI3K/Akt signaling pathways. These results show that the α5-nAChR/HIF-1α/VEGF axis is involved in nicotine-induced tumor cell proliferation, which suggests that α5-nAChR may serve as a potential anticancer target in nicotine-associated lung cancer. - Highlights

  14. Transcriptomic evaluation of the nicotinic acetylcholine receptor pathway in levamisole-resistant and -sensitive Oesophagostomum dentatum.

    Science.gov (United States)

    Romine, Nathan M; Martin, Richard J; Beetham, Jeffrey K

    2014-01-01

    Nematode anthelminthic resistance is widespread for the 3 major drug classes commonly used in agriculture: benzamidazoles, macrocyclic lactones, and nicotinic agonists e.g. levamisole. In parasitic nematodes the genetics of resistance is unknown other than to the benzimidazoles which primarily involve a single gene. In previous work with a levamisole resistant Oesophagostomum dentatum isolate, the nicotinic acetylcholine receptor (nAChR) exhibited decreased levamisole sensitivity. Here, using a transcriptomic approach on the same isolate, we investigate whether that decreased nAChR sensitivity is achieved via a 1-gene mechanism involving 1 of 27 nAChR pathway genes. 3 nAChR receptor subunit genes exhibited ≥2-fold change in transcript abundance: acr-21 and acr-25 increased, and unc-63 decreased. 4 SNPs having a ≥2-fold change in frequency were also identified. These data suggest that resistance is likely polygenic, involving modulated abundance of multiple subunits comprising the heteropentameric nAChR, and is not due to a simple 1-gene mechanism. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Nicotine effects on muscarinic receptor-mediated free Ca[Formula: see text] level changes in the facial nucleus following facial nerve injury.

    Science.gov (United States)

    Sun, Dawei; Zhou, Rui; Dong, Anbing; Sun, Wenhai; Zhang, Hongmei; Tang, Limin

    2016-06-01

    It was suggested that muscarinic, and nicotinic receptors increase free Ca[Formula: see text] levels in the facial nerve nucleus via various channels following facial nerve injury. However, intracellular Ca[Formula: see text] overload can trigger either necrotic or apoptotic cell death. It is assumed that, following facial nerve injury, the interactions of nicotinic and muscarinic acetylcholine receptors in facial nerve nucleus may negatively regulate free Ca[Formula: see text] concentrations in the facial nerve nucleus, which provide important information for the repair and regeneration of the facial nerve. The present study investigated the regulatory effects of nicotine on muscarinic receptor-mediated free calcium ion level changes in the facial nucleus in a rat model of facial nerve injury at 7, 30, and 90 days following facial nerve injury using laser confocal microscopy. The dose-dependent regulation of nicotine on muscarinic receptor-mediated free calcium ion level changes in the facial nucleus may decrease the range of free Ca[Formula: see text] increases following facial nerve injury, which is important for nerve cell regeneration. It is concluded that the negative effects of nicotine on muscarinic receptors are related to the [Formula: see text] subtype of nicotinic receptors.

  16. Nicotine Lozenges

    Science.gov (United States)

    Nicotine lozenges are used to help people stop smoking. Nicotine lozenges are in a class of medications called smoking cessation aids. They work by providing nicotine to your body to decrease the withdrawal symptoms ...

  17. Synergistic Effects of Genetic Variation in Nicotinic and Muscarinic Receptors on Visual Attention but Not Working Memory

    National Research Council Canada - National Science Library

    P. M. Greenwood; M.-K. Lin; R. Sundararajan; K. J. Fryxell; R. Parasuraman; L. L. Iversen

    2009-01-01

    .... We hypothesized that joint influences of nicotinic and muscarinic systems would be reflected in cognitive effects of normal variation in known SNPs in nicotinic (CHRNA4 rs1044396) and muscarinic (CHRM2 rs8191992) receptor genes. Exp...

  18. Some properties of human neuronal α7 nicotinic acetylcholine receptors fused to the green fluorescent protein

    Science.gov (United States)

    Palma, Eleonora; Mileo, Anna M.; Martínez-Torres, Ataúlfo; Eusebi, Fabrizio; Miledi, Ricardo

    2002-01-01

    The functional properties and cellular localization of the human neuronal α7 nicotinic acetylcholine (AcCho) receptor (α7 AcChoR) and its L248T mutated (mut) form were investigated by expressing them alone or as gene fusions with the enhanced version of the green fluorescent protein (GFP). Xenopus oocytes injected with wild-type (wt), mutα7, or the chimeric subunit cDNAs expressed receptors that gated membrane currents when exposed to AcCho. As already known, AcCho currents generated by wtα7 receptors decay much faster than those elicited by the mutα7 receptors. Unexpectedly, the fusion of GFP to the wt and mutated α7 receptors led to opposite results: the AcCho-current decay of the wt receptors became slower, whereas that of the mutated receptors was accelerated. Furthermore, repetitive applications of AcCho led to a considerable “run-down” of the AcCho currents generated by mutα7-GFP receptors, whereas those of the wtα7-GFP receptors remained stable or increased in amplitude. The AcCho-current run-down of mutα7-GFP oocytes was accompanied by a marked decrease of α-bungarotoxin binding activity. Fluorescence, caused by the chimeric receptors expressed, was seen over the whole oocyte surface but was more intense and abundant in the animal hemisphere, whereas it was much weaker in the vegetal hemisphere. We conclude that fusion of GFP to wtα7 and mutα7 receptors provides powerful tools to study the distribution and function of α7 receptors. We also conclude that fused genes do not necessarily recapitulate all of the properties of the original receptors. This fact must be borne close in mind whenever reporter genes are attached to proteins. PMID:11891308

  19. Enhanced nicotinic acetylcholine receptor-mediated [3H]norepinephrine release from neonatal rat hypothalamus.

    Science.gov (United States)

    O'Leary, K T; Leslie, F M

    2006-01-01

    Nicotinic acetylcholine receptor (nAChR)-evoked release of norepinephrine (NE) has been demonstrated in a number of brain regions that receive sole noradrenergic innervation from the locus coeruleus (LC). Many of these structures display enhanced nicotine-stimulated NE release in the neonate. We have examined the hypothalamus in order to determine if this region, which receives NE projections from both the LC and medullary catecholaminergic nuclei, also demonstrates maturational changes in nAChR-mediated NE release. Quantification of radiolabeled-NE release from rat hypothalamus slices by a maximally effective dose of nicotine revealed a peak response during the first postnatal week. This was followed by a decrease at postnatal day (P) 14, and a second peak at P21. Thereafter, release was equivalent to that observed at P14. Comparison of the pharmacological properties of nAChRs mediating NE release in neonatal (P7) and mature hypothalamus suggested involvement of different nAChR subtypes at the two ages. Using the selective toxin, DSP-4, nAChR-mediated NE release in the neonatal hypothalamus was shown to be from LC terminals. Our findings demonstrate an early sensitivity of hypothalamic LC terminals to nAChR regulation that may be associated with development of systems controlling critical homeostatic functions such as stress, feeding and cardiovascular regulation.

  20. The role of electrostatic interactions in governing anesthetic action on the torpedo nicotinic acetylcholine receptor.

    Science.gov (United States)

    Raines, Douglas E; Claycomb, Robert J

    2002-08-01

    Isoflurane and normal alkanols reduce the apparent agonist dissociation constant (Kd) of the nicotinic acetylcholine receptor (nAChR) at clinically relevant concentrations, whereas cyclopropane and butane do not. This suggests that electrostatic (hydrogen bonding and/or dipolar) interactions modulate anesthetic potency in this model receptor system. To further define the nature of these interactions, we quantified the potencies with which a heterologous group of general anesthetics reduces the nAChR's apparent Kd for acetylcholine. We assessed the importance that an anesthetic's molecular volume, ability to donate a hydrogen bond (hydrogen bond acidity), ability to accept a hydrogen bond (hydrogen bond basicity), and dipole moment play in determining aqueous potency. We found that aqueous anesthetic potency increases with molecular volume and decreases with hydrogen bond basicity but is unaffected by dipole moment and hydrogen bond acidity. These results suggest that anesthetics reduce the apparent agonist Kd of the nAChR by binding to a site that has a dipolarity and ability to accept hydrogen bonds that are similar to those of water, but a hydrogen bond-donating capacity that is less. Anesthetics representing a wide range of chemical classes reduce the apparent agonist dissociation constant of the Torpedo nicotinic acetylcholine receptor with aqueous potencies that are governed by their molecular volumes and hydrogen bond basicities. However, neither their hydrogen bond acidities nor dipole moments influence aqueous potency.

  1. Alpha-nicotinic acetylcholine receptor and tobacco smoke exposure : Effects on bronchial hyperresponsiveness in children

    NARCIS (Netherlands)

    Torjussen, Tale M.; Carlsen, Karin C. Lodrup; Munthe-Kaas, Monica C.; Mowinckel, Petter; Carlsen, Kai-Hakon; Helms, Peter J.; Gerritsen, Jorrit; Whyte, Moira K.; Lenney, Warren; Undlien, Dag E.; Shianna, Kevin V.; Zhu, Guohua; Pillai, Sreekumar G.

    Background: The CHRNA 3 and 5 genes on chromosome 15 encode the alpha subunits of the nicotinic acetylcholine receptor, mediating airway cholinergic activity. Polymorphisms are associated with cigarette smoking, chronic obstructive pulmonary disease, and lung cancer. Aims: To determine possible

  2. Characterization of nicotinic receptors involved in the release of noradrenaline from the hippocampus

    Energy Technology Data Exchange (ETDEWEB)

    Vizi, E.S. [Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, H-1450 Budapest (Hungary); Lajtha, A. [Center of Neurochemistry, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY (United States); Balla, A. [Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, H-1450 Budapest (Hungary); Sershen, H. [Center of Neurochemistry, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY (United States)

    1997-01-06

    The pharmacological features of putative nicotinic acetylcholine receptor sites involved in the release of [{sup 3}H]noradrenaline were assessed in rat hippocampus. The effect of nicotinic agonists to induce [{sup 3}H]noradrenaline release was examined in superfused slices. The nicotinic agonists (-)-epibatidine, (+)-anatoxin-a, dimethylphenylpiperazinium, (-)-nicotine and (-)-lobeline released [{sup 3}H]noradrenaline. The dose-response curves to nicotinic agonists were bell shaped, and indicated that their functional efficacies and potency vary across agonists. Maximal efficacy was seen with dimethylphenylpiperazinium and lobeline (E{sub max} values two to three times higher than other agonists). The rank order of potency for the agonists to release [{sup 3}H]noradrenaline was (-)-epibatidine (+)-anatoxin-a dimethylphenylpiperazinium cytisine nicotine (-)-lobeline. The nicotinic acetylcholine receptor antagonists [n-bungarotoxin (+)-tubocurarine hexamethonium>>{alpha}-bungarotoxin=dihydro-{beta}-erythroidine] and tetrodotoxin antagonized the effect of dimethylphenylpiperazinium to release [{sup 3}H]noradrenaline. The results, based on these pharmacological profiles, suggest the possible involvement of nicotinic acetylcholine receptor {alpha}3 and {beta}2 nicotinic acetylcholine receptor subunits in the control of [{sup 3}H]noradrenaline release from hippocampal slices. The absence of effect of {alpha}-bungarotoxin and {alpha}-conotoxin-IMI excludes the possible involvement of nicotinic acetylcholine receptors containing the {alpha}7 subunit. The release of [{sup 3}H]noradrenaline by dimethylphenylpiperazinium was Ca{sup 2+} dependent. Nifedipine failed to prevent the dimethylphenylpiperazinium-induced release of [{sup 3}H]noradrenaline, but Cd{sup 2+}, {omega}-conotoxin and Ca{sup 2+}-free conditions significantly reduced the dimethylphenylpiperazinium-induced release, suggesting that N-type voltage-sensitive Ca{sup 2+} channels are involved in the nicotinic

  3. Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuan, E-mail: yuan.xu@ki.se; Cardell, Lars-Olaf

    2014-02-15

    Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B{sub 2} receptor agonist) and des-Arg{sup 9}-bradykinin- (selective B{sub 1} receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE{sub 2}. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg{sup 9}-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B{sub 2} receptors, but not those on B{sub 1}. Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in

  4. Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism

    Science.gov (United States)

    2015-10-01

    AWARD NUMBER: W81XWH-13-1-0144 TITLE: Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism PRINCIPAL INVESTIGATOR...SUBTITLE 5a. CONTRACT NUMBER Dual Modulators of GABA-A and Alpha 7 Nicotinic Receptors for Treating Autism 5b. GRANT NUMBER W81XWH-13-1-0144 5c...ABSTRACT Autism spectrum disorder (ASD) is a polygenic signaling disorder that may result, in part, from an imbalance in excitatory and inhibitory

  5. α7-Nicotinic acetylcholine receptor: role in early odor learning preference in mice.

    Directory of Open Access Journals (Sweden)

    Jennifer L Hellier

    Full Text Available Recently, we have shown that mice with decreased expression of α7-nicotinic acetylcholine receptors (α7 in the olfactory bulb were associated with a deficit in odor discrimination compared to wild-type mice. However, it is unknown if mice with decreased α7-receptor expression also show a deficit in early odor learning preference (ELP, an enhanced behavioral response to odors with attractive value observed in rats. In this study, we modified ELP methods performed in rats and implemented similar conditions in mice. From post-natal days 5-18, wild-type mice were stroked simultaneously with an odor presentation (conditioned odor for 90 s daily. Control mice were only stroked, exposed to odor, or neither. On the day of testing (P21, mice that were stroked in concert with a conditioned odor significantly investigated the conditioned odor compared to a novel odor, as observed similarly in rats. However, mice with a decrease in α7-receptor expression that were stroked during a conditioned odor did not show a behavioral response to that odorant. These results suggest that decreased α7-receptor expression has a role in associative learning, olfactory preference, and/or sensory processing deficits.

  6. Inhibitory effects of tramadol on nicotinic acetylcholine receptors in adrenal chromaffin cells and in Xenopus oocytes expressing α7 receptors

    Science.gov (United States)

    Shiraishi, Munehiro; Minami, Kouichiro; Uezono, Yasuhito; Yanagihara, Nobuyuki; Shigematsu, Akio; Shibuya, Izumi

    2002-01-01

    Tramadol has been used clinically as an analgesic; however, the mechanism of its analgesic effects is still unknown.We used bovine adrenal chromaffin cells to investigate effects of tramadol on catecholamine secretion, nicotine-induced cytosolic Ca2+ concentration ([Ca2+]i) increases and membrane current changes. We also investigated effects of tramadol on α7 nicotinic acetylcholine receptors (AChRs) expressed in Xenopus oocytes.Tramadol concentration-dependently suppressed carbachol-induced catecholamine secretion to 60% and 27% of the control at the concentration of 10 and 100 μM, respectively, whereas it had little effect on veratridine- or high K+-induced catecholamine secretion.Tramadol also suppressed nicotine-induced ([Ca2+]i) increases in a concentration-dependent manner. Tramadol inhibited nicotine-induced inward currents, and the inhibition was unaffected by the opioid receptor antagonist naloxone.Tramadol inhibited nicotinic currents carried by α7 receptors expressed in Xenopus oocytes.Tramadol inhibited both α-bungarotoxin-sensitive and -insensitive nicotinic currents in bovine adrenal chromaffin cells.In conclusion, tramadol inhibits catecholamine secretion partly by inhibiting nicotinic AChR functions in a naloxone-insensitive manner and α7 receptors are one of those inhibited by tramadol. PMID:12010769

  7. Nicotinic Receptor Alpha7 Expression during Mouse Adrenal Gland Development

    Science.gov (United States)

    Gahring, Lorise C.; Myers, Elizabeth; Palumbos, Sierra; Rogers, Scott W.

    2014-01-01

    The nicotinic acetylcholine receptor alpha 7 (α7) is a ligand-activated ion channel that contributes to a diversity of cellular processes involved in development, neurotransmission and inflammation. In this report the expression of α7 was examined in the mouse developing and adult adrenal gland that expresses a green fluorescent protein (GFP) reporter as a bi-cistronic extension of the endogenous α7 transcript (α7G). At embryonic day 12.5 (E12.5) α7G expression was associated with the suprarenal ganglion and precursor cells of the adrenal gland. The α7G cells are catecholaminergic chromaffin cells as reflected by their progressive increase in the co-expression of tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) that is complete by E18.5. In the adult, α7G expression is limited to a subset of chromaffin cells in the adrenal medulla that cluster near the border with the adrenal cortex. These chromaffin cells co-express α7G, TH and DBH, but they lack phenylethanolamine N-methyltransferase (PNMT) consistent with only norepinephrine (NE) synthesis. These cell groups appear to be preferentially innervated by pre-ganglionic afferents identified by the neurotrophin receptor p75. No afferents identified by beta-III tubulin, neurofilament proteins or p75 co-expressed α7G. Occasional α7G cells in the pre-E14.5 embryos express neuronal markers consistent with intrinsic ganglion cells and in the adult some α7G cells co-express glutamic acid decarboxylase. The transient expression of α7 during adrenal gland development and its prominent co-expression by a subset of NE chromaffin cells in the adult suggests that the α7 receptor contributes to multiple aspects of adrenal gland development and function that persist into adulthood. PMID:25093893

  8. Phospholipase C activity affinity purifies with the Torpedo nicotinic acetylcholine receptor.

    Science.gov (United States)

    Labriola, Jonathan M; daCosta, Corrie J B; Wang, Shuzhi; Figeys, Daniel; Smith, Jeffrey C; Sturgeon, R Michel; Baenziger, John E

    2010-04-02

    Nicotinic acetylcholine receptors mediate fast synaptic transmission by fluxing ions across the membrane in response to neurotransmitter binding. We show here that during affinity purification of the nicotinic acetylcholine receptor from Torpedo, phosphatidic acid, but not other anionic or zwitterionic phospholipids, is hydrolyzed to diacylglycerol. The phospholipase C activity elutes with the acetylcholine receptor and is inhibited by a lipid phosphate phosphohydrolase inhibitor, sodium vanadate, but not a phosphatidate phosphohydrolase inhibitor, N-ethylmaleimide. Further, the hydrolysis product of phosphatidic acid, diacylglycerol, enhances the functional capabilities of the acetylcholine receptor in the presence of anionic lipids. We conclude that a phospholipase C activity, which appears to be specific for phosphatidic acid, is associated with the nicotinic acetylcholine receptor. The acetylcholine receptor may directly or indirectly influence lipid metabolism in a manner that enhances its own function.

  9. Nicotinic receptors in the dorsal and ventral hippocampus differentially modulate contextual fear conditioning.

    Science.gov (United States)

    Kenney, Justin W; Raybuck, Jonathan D; Gould, Thomas J

    2012-08-01

    Nicotine administration alters various forms of hippocampus-dependent learning and memory. Increasing work has found that the dorsal and ventral hippocampus differentially contribute to multiple behaviors. Thus, the present study examined whether the effects of nicotine in the dorsal and ventral hippocampus have distinct influences on contextual fear learning in male C57BL/6J mice. Direct infusion of nicotine into the dorsal hippocampus resulted in an enhancement of contextual fear learning, whereas nicotine infused into the ventral hippocampus resulted in deficits. Nicotine infusions into the ventral hippocampus did not alter hippocampus-independent cued fear conditioning or time spent in the open arm of the elevated plus maze, a measure of anxiety, suggesting that the effects are due to alterations in contextual learning and not other general processes. Finally, results from using direct infusions of MLA, a low-affinity α7 nicotinic acetylcholine receptor (nAChR) antagonist, in conjunction with systemic nicotine, provide evidence that α7-nAChRs in the ventral hippocampus mediate the detrimental effect of ventral hippocampal nicotine on contextual fear learning. These results suggest that with systemic nicotine administration, competition exists between the dorsal and ventral hippocampus for behavioral control over contextual learning. Copyright © 2012 Wiley Periodicals, Inc.

  10. Mapping of the acetylcholine binding site of the nicotinic acetylcholine receptor: [3H]nicotine as an agonist photoaffinity label.

    Science.gov (United States)

    Middleton, R E; Cohen, J B

    1991-07-16

    The agonist [3H]nicotine was used as a photoaffinity label for the acetylcholine binding sites on the Torpedo nicotinic acetylcholine receptor (AChR). [3H]nicotine binds at equilibrium with Keq = 0.6 microM to the agonist binding sites. Irradiation with 254-nm light of AChR-rich membranes equilibrated with [3H]nicotine resulted in covalent incorporation into the alpha- and gamma-subunits, which was inhibited by agonists and competitive antagonists but not by noncompetitive antagonists. Inhibition of labeling by d-tubocurarine demonstrated that the alpha-subunit was labeled via both agonist sites but the gamma-subunit was labeled only via the site that binds d-tubocurarine with high affinity. Within the alpha-subunit, 93% of the labeling was contained within a 20-kDa Staphylococcus aureus V8 proteolytic fragment beginning at Ser-173. Sequence analysis of this peptide indicated that approximately 80% of the incorporation was into Tyr-198, approximately 13% was into Cys-192, and approximately 7% was into Tyr-190. Chymotryptic digestion of the alpha-subunit confirmed that Tyr-198 was the principal amino acid labeled by [3H]nicotine. This confirmation required a novel radio-sequencing strategy employing omicron-phthalaldehyde, since the efficiency of photolabeling was low (approximately 1.0%) and the labeled chymotryptic peptide was not isolated in sufficient quantity to be identified by mass. [3H]Nicotine, which is the first photoaffinity agonist used, labels primarily Tyr-198 in contrast to competitive antagonist affinity labels, which label primarily Tyr-190 and Cys-192/Cys-193.

  11. Effects of methyllycaconitine (MLA), an alpha 7 nicotinic receptor antagonist, on nicotine- and cocaine-induced potentiation of brain stimulation reward.

    Science.gov (United States)

    Panagis, G; Kastellakis, A; Spyraki, C; Nomikos, G

    2000-05-01

    It has been shown that nicotine facilitates intracranial self-stimulation (ICSS) reward and that nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area (VTA) are of primary importance for its reinforcing and dependence-producing actions. Recently, we have shown that alpha 7 nicotinic receptors in the VTA contribute to both the acute effects of nicotine on the mesolimbic dopamine system, as well as to nicotine withdrawal reactions. However, it is not yet known whether the same receptor conformation is directly involved in the reinforcing actions of nicotine. Here, using the curve-shift method we studied the effects of methyllycaconitine (MLA), a selective alpha 7 receptor antagonist, microinjected (graded doses: 1, 3, 9 micrograms/microliter per side) into the VTA on the rewarding efficacy of lateral hypothalamic self-stimulation and on the systemic nicotine-induced potentiation of brain stimulation reward. MLA did not affect baseline self-stimulation. Nicotine produced a significant reduction in ICSS threshold, without altering maximal rates of responding, while MLA attenuated the effect of nicotine at the two lower doses. Given the reported interaction between nicotine and cocaine at both the neuronal and the behavioral level, we also examined whether alpha 7 receptor antagonism within the VTA can affect the reinforcing action of cocaine, as measured with ICSS. Interestingly, MLA attenuated the reinforcing effect of cocaine in all doses tested, without altering the maximal rate of responding, i.e. the performance of the animals. These results suggest that alpha 7 nAChRs in the VTA are involved in mediating the reinforcing actions of drugs of abuse, such as nicotine and cocaine, and provide evidence that alpha 7 nAChR antagonists may be clinically useful in attenuating the rewarding effects of addictive drugs.

  12. Fluorescent agonists for the Torpedo nicotinic acetylcholine receptor.

    Science.gov (United States)

    Krieger, Florian; Mourot, Alexandre; Araoz, Romulo; Kotzyba-Hibert, Florence; Molgó, Jordi; Bamberg, Ernst; Goeldner, Maurice

    2008-05-05

    We have synthesized a series of fluorescent acylcholine derivatives carrying different linkers that vary in length and structure and connect the acylcholine unit to the environment-sensitive fluorophores 7-(diethylamino)coumarin-3-carbonyl (DEAC) or N-(7-nitrobenz-2-oxa-1,3-diazol-yl) (NBD). The pharmacological properties of the fluorescent analogues were investigated on heterologously expressed nicotinic acetylcholine receptor (nAChR) from Torpedo californica and on oocytes transplanted with nAChR-rich Torpedo marmorata membranes. Agonist action strongly depends on the length and the structure of the linker. One particular analogue, DEAC-Gly-C6-choline, showed partial agonist behavior with about half of the maximum response of acetylcholine, which is at least 20 times higher than those observed with previously described fluorescent dansyl- and NBD-acylcholine analogues. Binding of DEAC-Gly-C6-choline to Torpedo nAChR induces a strong enhancement of fluorescence intensity. Association and displacement kinetic experiments revealed dissociation constants of 0.5 nM for the alphadelta-binding site and 15.0 nM for the alphagamma-binding site. Both the pharmacological and the spectroscopic properties of this agonist show great promise for characterizing the allosteric mechanism behind the function of the Torpedo nAChR, as well as for drug-screening studies.

  13. Nicotinic acid receptor abnormalities in human skin cancer: implications for a role in epidermal differentiation.

    Directory of Open Access Journals (Sweden)

    Yira Bermudez

    Full Text Available Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through G(i-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells.Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional G(i-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional.The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s of nicotinic acid receptors in human skin homeostasis.

  14. Multiple inhibitory actions of lidocaine on Torpedo nicotinic acetylcholine receptors transplanted to Xenopus oocytes.

    Science.gov (United States)

    Alberola-Die, Armando; Martinez-Pinna, Juan; González-Ros, José Manuel; Ivorra, Isabel; Morales, Andrés

    2011-06-01

    Lidocaine is a local anaesthetic that blocks sodium channels, but also inhibits several ligand-gated ion-channels. The aim of this work was to unravel the mechanisms by which lidocaine blocks Torpedo nicotinic receptors transplanted to Xenopus oocytes. Acetylcholine-elicited currents were reversibly blocked by lidocaine, in a concentration dependent manner. At doses lower than the IC(50) , lidocaine blocked nicotinic receptors only at negative potentials, indicating an open-channel blockade; the binding site within the channel was at about 30% of the way through the electrical field across the membrane. In the presence of higher lidocaine doses, nicotinic receptors were blocked both at positive and negative potentials, acetylcholine dose-response curve shifted to the right and lidocaine pre-application, before its co-application with acetylcholine, enhanced the current inhibition, indicating all together that lidocaine also blocked resting receptors; besides, it increased the current decay rate. When lidocaine, at low doses, was co-applied with 2-(triethylammonio)-N-(2,6-dimethylphenyl) acetamide bromide, edrophonium or 1,5-bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide, which are quaternary-ammonium molecules that also blocked nicotinic receptors, there was an additive inhibitory effect, indicating that these molecules bound to different sites within the channel pore. These results prove that lidocaine blocks nicotinic receptors by several independent mechanisms and evidence the diverse and complex modulation of this receptor by structurally related molecules. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  15. Effect of beta-adrenergic receptor antagonists on nicotine-induced tail-tremor in rats.

    Science.gov (United States)

    Suemaru, K; Gomita, Y; Furuno, K; Araki, Y

    1993-09-01

    The effects of various beta-adrenergic receptor antagonists on nicotine-induced tail-tremor were investigated in rats. Atenolol (5 and 10 mg/kg, IP), arotinolol (5 and 10 mg/kg, IP), and carteolol (5 and 10 mg/kg, IP), hydrophilic beta-adrenergic receptor antagonists, did not affect the tail-tremor induced by nicotine given at a dose of 0.5 mg/kg SC. However, propranolol (5-20 mg/kg, IP) and pindolol (5-20 mg/kg, IP), nonselective and lipophilic beta-adrenergic receptor antagonists, did suppress the tail-tremor dose dependently. In contrast, metoprolol (5-20 mg/kg, IP), lipophilic and beta 1-selective adrenergic receptor antagonists, did not show such an effect. These results suggest that nicotine-induced tail-tremors may be mediated through central beta 2-adrenergic receptors as an appearance and developmental mechanism.

  16. Mice Lacking the β4 Subunit of the Nicotinic Acetylcholine Receptor Show Memory Deficits, Altered Anxiety- and Depression-Like Behavior, and Diminished Nicotine-Induced Analgesia

    Science.gov (United States)

    Semenova, Svetlana; Contet, Candice; Roberts, Amanda J.

    2012-01-01

    Rationale: The role of β4-containing nicotinic acetylcholine receptors (nAChRs) in cognition, anxiety, depression, and analgesia in the absence of nicotine is unclear. Methods: Wild-type (β4+/+) and knockout (β4−/−) mice for the nAChR β4 subunit were tested in behavioral tests assessing cognitive function, affective behaviors, and nociception. Results: There were no learning and memory deficits in β4−/− mice compared with β4+/+ mice during the acquisition of the Barnes maze, contextual fear conditioning, and Y maze tasks. In the Barnes maze memory retention test, male β4−/− mice showed reduced use of the spatial search strategy, indicating small spatial memory deficits compared with β4+/+ mice. In the cue-induced fear conditioning memory retention test, β4−/− mice exhibited reduced freezing time compared with β4+/+ mice. Compared with β4+/+ mice, β4−/− mice exhibited decreased anxiety-like behavior in the light–dark box. Depression-like behavior in β4−/− mice was decreased in the tail suspension test and increased in the forced swim test compared with β4+/+ mice. β4−/− mice did not differ from β4+/+ mice in basal nociception but were less sensitive to the antinociceptive effect of nicotine in 2 tests of acute thermal pain. Conclusions: Lack of β4-containing nAChRs resulted in small deficits in hippocampus- and amygdala-dependent memory retention functions. β4-containing nAChRs are involved in anxiety- and depression-like behaviors and contribute to the analgesic effects of nicotine. PMID:22573727

  17. Minor structural changes in nicotinoid insecticides confer differential subtype selectivity for mammalian nicotinic acetylcholine receptors

    Science.gov (United States)

    Tomizawa, Motohiro; Casida, John E

    1999-01-01

    The major nitroimine insecticide imidacloprid (IMI) and the nicotinic analgesics epibatidine and ABT-594 contain the 6-chloro-3-pyridinyl moiety important for high activity and/or selectivity. ABT-594 has considerable nicotinic acetylcholine receptor (AChR) subtype specificity which might carry over to the chloropyridinyl insecticides. This study considers nine IMI analogues for selectivity in binding to immuno-isolated α1, α3 and α7 containing nicotinic AChRs and to purported α4β2 nicotinic AChRs.α1- and α3-Containing nicotinic AChRs (both immuno-isolated by mAb 35, from Torpedo and human neuroblastoma SH-SY5Y cells, respectively) are between two and four times more sensitive to DN-IMI than to (−)-nicotine.With immuno-isolated α3 nicotinic AChRs, the tetrahydropyrimidine analogues of IMI with imine or nitromethylene substituents are 3–4 fold less active than (−)-nicotine. The structure-activity profile with α3 nicotinic AChRs from binding assays is faithfully reproduced in agonist potency as induction of 86rubidium ion efflux in intact cells.α7-Containing nicotinic AChRs of SH-SY5Y cells (immuno-isolated by mAb 306) and rat brain membranes show maximum sensitivity to the tetrahydropyrimidine analogue of IMI with the nitromethylene substituent.The purported α4β2 nicotinic AChRs [mouse (Chao & Casida, 1997) and rat brain] are similar in sensitivity to DN-IMI, the tetrahydropyrimidine nitromethylene and nicotine.The commercial insecticides (IMI, acetamiprid and nitenpyram) have low to moderate potency at the α3 and purported α4β2 nicotinic AChRs and are essentially inactive at α1 and α7 nicotinic AChRs.In conclusion, the toxicity of the analogues and metabolites of nicotinoid insecticides in mammals may involve action at multiple receptor subtypes with selectivity conferred by minor structural changes. PMID:10369463

  18. Neuroprotection by donepezil against glutamate excitotoxicity involves stimulation of α7 nicotinic receptors and internalization of NMDA receptors

    Science.gov (United States)

    Shen, H; Kihara, T; Hongo, H; Wu, X; Kem, WR; Shimohama, S; Akaike, A; Niidome, T; Sugimoto, H

    2010-01-01

    BACKGROUND AND PURPOSE Glutamate excitotoxicity may be involved in ischaemic injury to the CNS and some neurodegenerative diseases, such as Alzheimer's disease. Donepezil, an acetylcholinesterase (AChE) inhibitor, exerts neuroprotective effects. Here we demonstrated a novel mechanism underlying the neuroprotection induced by donepezil. EXPERIMENTAL APPROACH Cell damage in primary rat neuron cultures was quantified by lactate dehydrogenase release. Morphological changes associated with neuroprotective effects of nicotine and AChE inhibitors were assessed by immunostaining. Cell surface levels of the glutamate receptor sub-units, NR1 and NR2A, were analyzed using biotinylation. Immunoblot was used to measure protein levels of cleaved caspase-3, total NR1, total NR2A and phosphorylated NR1. Immunoprecipitation was used to measure association of NR1 with the post-synaptic protein, PSD-95. Intracellular Ca2+ concentrations were measured with fura 2-acetoxymethylester. Caspase 3-like activity was measured using enzyme substrate, 7-amino-4-methylcoumarin (AMC)-DEVD. KEY RESULTS Levels of NR1, a core subunit of the NMDA receptor, on the cell surface were significantly reduced by donepexzil. In addition, glutamate-mediated Ca2+ entry was significantly attenuated by donepezil. Methyllycaconitine, an inhibitor of α7 nicotinic acetylcholine receptors (nAChR), inhibited the donepezil-induced attenuation of glutamate-mediated Ca2+ entry. LY294002, a phosphatidyl inositol 3-kinase (PI3K) inhibitor, had no effect on attenuation of glutamate-mediated Ca2+ entry induced by donepezil. CONCLUSIONS AND IMPLICATIONS Decreased glutamate toxicity through down-regulation of NMDA receptors, following stimulation of α7 nAChRs, could be another mechanism underlying neuroprotection by donepezil, in addition to up-regulating the PI3K-Akt cascade or defensive system. PMID:20718745

  19. Neuronal nicotinic receptors as analgesic targets: It’s a winding road

    OpenAIRE

    Umana, Iboro C.; Daniele, Claire A.; McGehee, Daniel S.

    2013-01-01

    Along with their well known role in nicotine addiction and autonomic physiology, neuronal nicotinic receptors (nAChRs) also have profound analgesic effects in animal models and humans. This is not a new idea, even in the early 1500s, soon after tobacco was introduced to the new world, its proponents listed pain relief among the beneficial properties of smoking. In recent years, analgesics that target specific nAChR subtypes have shown highly efficacious antinociceptive properties in acute and...

  20. Serotoninergic dorsal raphe neurons possess functional postsynaptic nicotinic acetylcholine receptors.

    Science.gov (United States)

    Galindo-Charles, Luis; Hernandez-Lopez, Salvador; Galarraga, Elvira; Tapia, Dagoberto; Bargas, José; Garduño, Julieta; Frías-Dominguez, Carmen; Drucker-Colin, René; Mihailescu, Stefan

    2008-08-01

    Very few neurons in the telencephalon have been shown to express functional postsynaptic nicotinic acetylcholine receptors (nAChRs), among them, the noradrenergic and dopaminergic neurons. However, there is no evidence for postsynaptic nAChRs on serotonergic neurons. In this study, we asked if functional nAChRs are present in serotonergic (5-HT) and nonserotonergic (non-5-HT) neurons of the dorsal raphe nucleus (DRN). In rat midbrain slices, field stimulation at the tegmental pedunculopontine (PPT) nucleus evoked postsynaptic currents (eEPSCs) with different components in DRN neurons. After blocking the glutamatergic and GABAergic components, the remaining eEPSCs were blocked by mecamylamine and reduced by either the selective alpha7 nAChR antagonist methyllycaconitine (MLA) or the selective alpha4beta2 nAChR antagonist dihydro-beta-eritroidine (DHbetaE). Simultaneous addition of MLA and DHbetaE blocked all eEPSCs. Integrity of the PPT-DRN pathway was assessed by both anterograde biocytin tracing and antidromic stimulation from the DRN. Inward currents evoked by the direct application of acetylcholine (ACh), in the presence of atropine and tetrodotoxin, consisted of two kinetically different currents: one was blocked by MLA and the other by DHbetaE; in both 5-HT and non-5-HT DR neurons. Analysis of spontaneous (sEPSCs) and evoked (eEPSCs) synaptic events led to the conclusion that nAChRs were located at the postsynaptic membrane. The possible implications of these newly described nAChRs in various physiological processes and behavioral events, such as the wake-sleep cycle, are discussed.

  1. Conditional Knockout of NMDA Receptors in Dopamine Neurons Prevents Nicotine-Conditioned Place Preference

    Science.gov (United States)

    Phillip Wang, Lei; Li, Fei; Shen, Xiaoming; Tsien, Joe Z.

    2010-01-01

    Nicotine from smoking tobacco produces one of the most common forms of addictive behavior and has major societal and health consequences. It is known that nicotine triggers tobacco addiction by activating nicotine acetylcholine receptors (nAChRs) in the midbrain dopaminergic reward system, primarily via the ventral tegmental area. Heterogeneity of cell populations in the region has made it difficult for pharmacology-based analyses to precisely assess the functional significance of glutamatergic inputs to dopamine neurons in nicotine addiction. By generating dopamine neuron-specific NR1 knockout mice using cre/loxP-mediated method, we demonstrate that genetic inactivation of the NMDA receptors in ventral tegmental area dopamine neurons selectively prevents nicotine-conditioned place preference. Interestingly, the mutant mice exhibit normal performances in the conditioned place aversion induced by aversive air puffs. Therefore, this selective effect on addictive drug-induced reinforcement behavior suggests that NMDA receptors in the dopamine neurons are critical for the development of nicotine addiction. PMID:20062537

  2. The neuronal nicotinic alpha4beta2 receptor has a high maximal probability of being open.

    Science.gov (United States)

    Li, Ping; Steinbach, Joe H

    2010-08-01

    A fundamental property of transmitter-gated ion channels is the probability a channel will be open (P(open)) when stimulated by a concentration of agonist that elicits a maximal response. This value is critical for interpreting steady-state concentration-response relationships in terms of channel activation, and for understanding the actions of drugs that potentiate responses. We used analysis of non-stationary noise to estimate the maximal probability the nicotinic alpha4beta2 receptor is open. HEK293 cells stably transfected to express human alpha4beta2 nicotinic receptors were studied using whole-cell voltage clamp. Nicotinic agonists (acetylcholine, nicotine, cytisine and 5-iodo A-85380) were applied, and the relationship between variance of the elicited whole-cell current and mean current was analysed. The variance did not increase linearly with the mean current. For acetylcholine and nicotine the relationship between variance and mean indicates that the maximal P(open) is greater than 0.8. The number of agonist-activatable channels was estimated to be about 1000 per cell. The mean single channel conductance at -60 mV was indistinguishable when currents were elicited by acetylcholine (18 pS), nicotine (17 pS) or 5-iodo A-85380 (17 pS), whereas the value for cytisine was larger (24 pS). The neuronal nicotinic alpha4beta2 receptor has a maximal probability of being open that is greater than 0.8. This conclusion applies to the receptor containing three alpha4 and two beta2 subunits (the low-sensitivity stoichiometry), but may not apply to the receptor containing two alpha4 and three beta2 subunits (the high-sensitivity stoichiometry).

  3. Genetic deletion of the adenosine A(2A) receptor prevents nicotine-induced upregulation of alpha 7, but not alpha 4 beta 2*nicotinic acetylcholine receptor binding in the brain

    NARCIS (Netherlands)

    Metaxas, A.; Al-Hasani, R.; Farshim, P.; Tubby, K.; Berwick, A.; Ledent, C.; Hourani, S.; Kitchen, I.; Bailey, A.

    2013-01-01

    Considerable evidence indicates that adenosine A2Areceptors (A2ARs) modulate cholinergic neurotransmission, nicotinic acetylcholine receptor (nAChR) function, and nicotine-induced behavioural effects. To explore the interaction between A2Aand nAChRs, we examined if

  4. Menthol decreases oral nicotine aversion in C57BL/6 mice through a TRPM8-dependent mechanism.

    Science.gov (United States)

    Fan, Lu; Balakrishna, Shrilatha; Jabba, Sairam V; Bonner, Pamela E; Taylor, Seth R; Picciotto, Marina R; Jordt, Sven-Eric

    2016-11-01

    Nicotine is a major oral irritant in smokeless tobacco products and has an aversive taste. Mentholated smokeless tobacco products are highly popular, suggesting that menthol increases their palatability and may facilitate initiation of product use. While menthol is known to reduce respiratory irritation by tobacco smoke irritants, it is not known whether this activity extends to oral nicotine and its aversive effects. The two-bottle choice drinking assay was used to characterise aversion and preference in C57BL/6 mice to a range of menthol concentrations (10-200 µg/mL). Then, effects of menthol on oral nicotine aversion were determined. Responses were compared with those in mice deficient in the cold/menthol receptor, TRPM8, expressed in trigeminal sensory neurons innervating the oral cavity. Mice showed aversion to menthol concentrations of 100 µg/mL and above. When presented with a highly aversive concentration of nicotine (200 µg/mL), mice preferred solutions with 50 or 100 µg/mL menthol added over nicotine alone. In contrast to wild-type mice, Trpm8-/- showed a strong aversion to mentholated (100 µg/mL) nicotine (200 µg/mL) and preferred nicotine alone. Trpm8-/- mice show aversion to lower concentrations of menthol than wild-type mice. Oral menthol can reduce the aversive effects of oral nicotine and, at higher concentrations, acts as an irritant by itself. Menthol's effects in relation to nicotine require TRPM8, the cool temperature sensing ion channel that activates analgesic and counterirritant mechanisms. These mechanisms may underlie preference for menthol-containing smokeless tobacco products and may facilitate initiation of product use. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  5. Bispyridinium Compounds Inhibit Both Muscle and Neuronal Nicotinic Acetylcholine Receptors in Human Cell Lines.

    Directory of Open Access Journals (Sweden)

    Avi Ring

    Full Text Available Standard treatment of poisoning by organophosphorus anticholinesterases uses atropine to reduce the muscarinic effects of acetylcholine accumulation and oximes to reactivate acetylcholinesterase (the effectiveness of which depends on the specific anticholinesterase, but does not directly address the nicotinic effects of poisoning. Bispyridinium molecules which act as noncompetitive antagonists at nicotinic acetylcholine receptors have been identified as promising compounds and one has been shown to improve survival following organophosphorus poisoning in guinea-pigs. Here, we have investigated the structural requirements for antagonism and compared inhibitory potency of these compounds at muscle and neuronal nicotinic receptors and acetylcholinesterase. A series of compounds was synthesised, in which the length of the polymethylene linker between the two pyridinium moieties was increased sequentially from one to ten carbon atoms. Their effects on nicotinic receptor-mediated calcium responses were tested in muscle-derived (CN21 and neuronal (SH-SY5Y cells. Their ability to inhibit acetylcholinesterase activity was tested using human erythrocyte ghosts. In both cell lines, the nicotinic response was inhibited in a dose-dependent manner and the inhibitory potency of the compounds increased with greater linker length between the two pyridinium moieties, as did their inhibitory potency for human acetylcholinesterase activity in vitro. These results demonstrate that bispyridinium compounds inhibit both neuronal and muscle nicotinic receptors and that their potency depends on the length of the hydrocarbon chain linking the two pyridinium moieties. Knowledge of structure-activity relationships will aid the optimisation of molecular structures for therapeutic use against the nicotinic effects of organophosphorus poisoning.

  6. Covalent attachment of antagonists to the a7 nicotinic acetylcholine receptor: synthesis and reactivity of substituted maleimides

    DEFF Research Database (Denmark)

    Ambrus, Joseph I; Halliday, Jill I; Kanizaj, Nicholas

    2012-01-01

    The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR).......The 3-methylmaleimide congeners of the natural product methyllycaconitine (MLA) and an analogue covalently attach to functional cysteine mutants of the a7 nicotinic acetylcholine receptor (nAChR)....

  7. The μ-opioid receptor gene and smoking initiation and nicotine dependence

    Directory of Open Access Journals (Sweden)

    Kendler Kenneth S

    2006-08-01

    Full Text Available Abstract The gene encoding the mu-opioid receptor (OPRM1 is reported to be associated with a range of substance dependence. Experiments in knockout mice indicate that the mu-opioid receptor may mediate reinforcing effects of nicotine. In humans, opioid antagonist naltrexone may reduce the reinforcing effects of tobacco smoking. Additionally, the OPRM1 gene is located in a region showing linkage to nicotine dependence. The OPRM1 is thus a plausible candidate gene for smoking behavior. To investigate whether OPRM1 contributes to the susceptibility of smoking initiation and nicotine dependence, we genotyped 11 SNPs in the gene for 688 Caucasian subjects of lifetime smokers and nonsmokers. Three SNPs showed nominal significance for smoking initiation and one reached significance for nicotine dependence. The global test for three-marker (rs9479757-rs2075572-rs10485057 haplotypes was significant for smoking initiation (p = 0.0022. The same three-marker haplotype test was marginal (p = 0.0514 for nicotine dependence. These results suggest that OPRM1 may be involved in smoking initiation and nicotine dependence.

  8. Effect of galantamine on the human α7 neuronal nicotinic acetylcholine receptor, the Torpedo nicotinic acetylcholine receptor and spontaneous cholinergic synaptic activity

    Science.gov (United States)

    Texidó, Laura; Ros, Esteve; Martín-Satué, Mireia; López, Susana; Aleu, Jordi; Marsal, Jordi; Solsona, Carles

    2005-01-01

    Various types of anticholinesterasic agents have been used to improve the daily activities of Alzheimer's disease patients. It was recently demonstrated that Galantamine, described as a molecule with anticholinesterasic properties, is also an allosteric enhancer of human α4β2 neuronal nicotinic receptor activity. We explored its effect on the human α7 neuronal nicotinic acetylcholine receptor (nAChR) expressed in Xenopus oocytes. Galantamine, at a concentration of 0.1 μM, increased the amplitude of acetylcholine (ACh)-induced ion currents in the human α7 nAChR expressed in Xenopus oocytes, but caused inhibition at higher concentrations. The maximum effect of galantamine, an increase of 22% in the amplitude of ACh-induced currents, was observed at a concentration of 250 μM Ach. The same enhancing effect was obtained in oocytes transplanted with Torpedo nicotinic acetylcholine receptor (AChR) isolated from the electric organ, but in this case the optimal concentration of galantamine was 1 μM. In this case, the maximum effect of galantamine, an increase of 35% in the amplitude of ACh-induced currents, occurred at a concentration of 50 μM ACh. Galantamine affects not only the activity of post-synaptic receptors but also the activity of nerve terminals. At a concentration of 1 μM, quantal spontaneous events, recorded in a cholinergic synapse, increased their amplitude, an effect which was independent of the anticholinesterasic activity associated with this compound. The anticholinesterasic effect was recorded in preparations treated with a galantamine concentration of 10 μM. In conclusion, our results show that galantamine enhances human α7 neuronal nicotinic ACh receptor activity. It also enhances muscular AChRs and the size of spontaneous cholinergic synaptic events. However, only a very narrow range of galantamine concentrations can be used for enhancing effects. PMID:15834443

  9. Involvement of cholinergic nicotinic receptors in the menthol-induced gastric relaxation.

    Science.gov (United States)

    Amato, Antonella; Serio, Rosa; Mulè, Flavia

    2014-12-15

    We have previously demonstrated that menthol reduces murine gastric tone in part through a neural mechanism, involving adrenergic pathways and reduction of ongoing release of acetylcholine from enteric nerves. In the present study we aimed to verify whether the gastric relaxation to menthol may be triggered by interaction with neural receptors or ionic channels proteins, such as transient receptor potential (TRP)-melastatin8 (TRPM8), TRP-ankyrin 1 (TRPA1), 5-hydroxytriptamine 3 (5-HT3) receptor or cholinergic nicotinic receptors. Spontaneous mechanical activity was detected in vitro as changes in intraluminal pressure from isolated mouse stomach. Menthol (0.3-30 mM) induced gastric relaxation which was not affected by 5-benzyloxytryptamine, a TRPM8 receptor antagonist, HC030031, a TRPA1 channel blocker. In addition, allylisothiocyanate, a TRPA1 agonist, but not (2S,5R)-2-Isopropyl-N-(4-methoxyphenyl)-5-methylcyclohexanecarboximide, a selective TRPM8 agonist, induced gastric relaxation. Genic expression of TRPA1, but not of TRPM8, was revealed in mouse stomach. Indeed, menthol-induced gastric relaxation was significantly reduced by hexamethonium, cholinergic nicotinic receptor antagonist. Menthol, at concentrations that failed to affect gastric tone, reduced the contraction induced by dimethylphenylpiperazinium, nicotinic receptor agonist. The joint application of hexamethonium and atropine, muscarinc receptor antagonist, or hexamethonium and phentholamine, α-adrenergic receptor antagonist, did not produce any additive reduction of the relaxant response to menthol. Lastly, ondansetron, a 5-HT3 receptor antagonist, was ineffective. In conclusion, our study suggests that nicotinic receptors, but not TRP and 5-HT3 receptors, are molecular targets for menthol inducing murine gastric relaxation, ultimately due to the reduction of acetylcholine release from enteric nerves. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Activation of α7 nicotinic acetylcholine receptor by nicotine selectively up-regulates cyclooxygenase-2 and prostaglandin E2 in rat microglial cultures

    Directory of Open Access Journals (Sweden)

    Minghetti Luisa

    2005-01-01

    Full Text Available Abstract Background Nicotinic acetylcholine (Ach receptors are ligand-gated pentameric ion channels whose main function is to transmit signals for the neurotransmitter Ach in peripheral and central nervous system. However, the α7 nicotinic receptor has been recently found in several non-neuronal cells and described as an important regulator of cellular function. Nicotine and ACh have been recently reported to inhibit tumor necrosis factor-α (TNF-α production in human macrophages as well as in mouse microglial cultures. In the present study, we investigated whether the stimulation of α7 nicotinic receptor by the specific agonist nicotine could affect the functional state of activated microglia by promoting and/or inhibiting the release of other important pro-inflammatory and lipid mediator such as prostaglandin E2. Methods Expression of α7 nicotinic receptor in rat microglial cell was examined by RT-PCR, immunofluorescence staining and Western blot. The functional effects of α7 receptor activation were analyzed in resting or lipopolysaccharide (LPS stimulated microglial cells pre-treated with nicotine. Culture media were assayed for the levels of tumor necrosis factor, interleukin-1β, nitric oxide, interleukin-10 and prostaglandin E2. Total RNA was assayed by RT-PCR for the expression of COX-2 mRNA. Results Rat microglial cells express α7 nicotinic receptor, and its activation by nicotine dose-dependently reduces the LPS-induced release of TNF-α, but has little or no effect on nitric oxide, interleukin-10 and interleukin-1β. By contrast, nicotine enhances the expression of cyclooxygenase-2 and the synthesis of one of its major products, prostaglandin E2. Conclusions Since prostaglandin E2 modulates several macrophage and lymphocyte functions, which are instrumental for inflammatory resolution, our study further supports the existence of a brain cholinergic anti-inflammatory pathway mediated by α7 nicotinic receptor that could be

  11. Pesticide exposure during pregnancy, like nicotine, affects the brainstem α7 nicotinic acetylcholine receptor expression, increasing the risk of sudden unexplained perinatal death.

    Science.gov (United States)

    Lavezzi, Anna Maria; Cappiello, Achille; Pusiol, Teresa; Corna, Melissa Felicita; Termopoli, Veronica; Matturri, Luigi

    2015-01-15

    This study indicates the impact of nicotine and pesticides (organochlorine and organophosphate insecticides used in agriculture) on neuronal α7-nicotinic acetylcholine receptor expression in brainstem regions receiving cholinergic projections in human perinatal life. An in-depth anatomopathological examination of the autonomic nervous system and immunohistochemistry to analyze the α7-nicotinic acetylcholine receptor expression in the brainstem from 44 fetuses and newborns were performed. In addition, the presence of selected agricultural pesticides in cerebral cortex samples of the victims was determined by specific analytical procedures. Hypodevelopment of brainstem structures checking the vital functions, frequently associated with α7-nicotinic acetylcholine receptor immunopositivity and smoke absorption in pregnancy, was observed in high percentages of victims of sudden unexpected perinatal death. In nearly 30% of cases however the mothers never smoked, but lived in rural areas. The search for pesticides highlighted in many of these cases traces of both organochlorine and organophosphate pesticides. We detain that exposition to pesticides in pregnancy produces homologous actions to those of nicotine on neuronal α7-nicotinic acetylcholine receptor, allowing to developmental alterations of brainstem vital centers in victims of sudden unexplained death. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Differential modulation of nicotine-induced gemcitabine resistance by GABA receptor agonists in pancreatic cancer cell xenografts and in vitro.

    Science.gov (United States)

    Banerjee, Jheelam; Al-Wadei, Hussein An; Al-Wadei, Mohammed H; Dagnon, Koami; Schuller, Hildegard M

    2014-09-27

    Pancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicotine-induced gemcitabine resistance in pancreatic cancer. Using mouse xenografts from the gemcitabine--sensitive pancreatic cancer cell line BXPC-3, we tested the effects of GABA and baclofen on nicotine-induced gemcitabine resistance. The levels of cAMP, p-SRC, p-ERK, p-AKT, p-CREB and cleaved caspase-3 in xenograft tissues were determined by ELISA assays. Expression of the two GABA-B receptors, metalloproteinase-2 and 9 and EGR-1 in xenograft tissues was monitored by Western blotting. Mechanistic studies were conducted in vitro, using cell lines BXPC-3 and PANC-1 and included analyses of cAMP production by ELISA assay and Western blots to determine protein expression of GABA-B receptors, metalloproteinase-2 and 9 and EGR-1. Our data show that GABA was as effective as gemcitabine and significantly reversed gemcitabine resistance induced by low dose nicotine in xenografts whereas baclofen did not. These effects of GABA were accompanied by decreases in cAMP, p-CREB, p-AKT, p-Src, p-ERK metalloproteinases-9 and -2 and EGR-1 and increases in cleaved caspase-3 in xenografts whereas baclofen had the opposite effects. In vitro exposure of cells to single doses or seven days of nicotine induced the protein expression of MMP-2, MMP-9 and EGR-1 and these responses were blocked by GABA. Baclofen downregulated the protein expression of GABA-B-Rs in xenograft tissues and in cells exposed to baclofen for seven days in vitro. This response was accompanied by inversed baclofen effects from inhibition of

  13. Mood and anxiety regulation by nicotinic acetylcholine receptors: A potential pathway to modulate aggression and related behavioral states.

    Science.gov (United States)

    Picciotto, Marina R; Lewis, Alan S; van Schalkwyk, Gerrit I; Mineur, Yann S

    2015-09-01

    The co-morbidity between smoking and mood disorders is striking. Preclinical and clinical studies of nicotinic effects on mood, anxiety, aggression, and related behaviors, such as irritability and agitation, suggest that smokers may use the nicotine in tobacco products as an attempt to self-medicate symptoms of affective disorders. The role of nicotinic acetylcholine receptors (nAChRs) in circuits regulating mood and anxiety is beginning to be elucidated in animal models, but the mechanisms underlying the effects of nicotine on aggression-related behavioral states (ARBS) are still not understood. Clinical trials of nicotine or nicotinic medications for neurological and psychiatric disorders have often found effects of nicotinic medications on ARBS, but few trials have studied these outcomes systematically. Similarly, the increase in ARBS resulting from smoking cessation can be resolved by nicotinic agents, but the effects of nicotinic medications on these types of mental states and behaviors in non-smokers are less well understood. Here we review the literature on the role of nAChRs in regulating mood and anxiety, and subsequently on the closely related construct of ARBS. We suggest avenues for future study to identify how nAChRs and nicotinic agents may play a role in these clinically important areas. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Nicotinic acetylcholine receptor gene expression is altered in burn patients.

    Science.gov (United States)

    Osta, Walid A; El-Osta, Mohamed A; Pezhman, Eric A; Raad, Robert A; Ferguson, Kris; McKelvey, George M; Marsh, Harold M; White, Michael; Perov, Samuel

    2010-05-01

    Burn patients have been observed to be more susceptible to the hyperkalemic effect of the depolarizing muscle relaxant succinylcholine. Changes in nicotinic acetylcholine receptor (nAChR) subunit composition may alter electrophysiologic, pharmacologic, and metabolic characteristics of the receptor inducing hyperkalemia on exposure to succinylcholine. No studies have been performed that show the upregulation and/or alteration of nAChR subunit composition in human burn patients. The scarcity of studies performed on humans with burn injury is mainly attributable to the technical and ethical difficulties in obtaining muscle biopsies at different time frames of illness in these acutely injured patients. nAChRs are expressed in oral keratinocytes and are upregulated or altered in smokers. However, no studies have addressed the expression of nAChRs in the oral mucosa of burn patients. Buccal mucosal scrapings were collected from 9 burn patients and 6 control nonburn surgical intensive care unit patients. For burn and control patients, tissues were collected upon presentation (time: 0 hour) and at time points 12, 24, and 48 hours, 1 week, and 2 weeks. Gene expression of the nAChR subunits alpha1, alpha7, gamma, and epsilon were performed using real-time reverse transcriptase polymerase chain reaction. alpha7 and gamma nAChR genes were significantly upregulated in burn patients, whereas alpha1 and epsilon nAChR genes were minimally affected, showing no significant changes over time. Over the 2 weeks of measurement, an upregulation of the alpha7 and gamma genes occurred in both burn and control patients; however, the proportion of alpha7 and gamma subunit increases was significantly higher in burn patients than in control surgical intensive care unit patients. The relationship between the thermal injury and the observed alteration in gene expression suggests a possible cause/effect relationship. This effect was observed at a site not affected by the burn injury and in

  15. Melatonin Administration Alters Nicotine Preference Consumption via Signaling Through High-Affinity Melatonin Receptors

    Science.gov (United States)

    Horton, William J.; Gissel, Hannah J.; Saboy, Jennifer E.; Wright, Kenneth P.; Stitzel, Jerry A.

    2015-01-01

    Rationale While it is known that tobacco use varies across the 24-hour day, the time-of-day effects are poorly understood. Findings from several previous studies indicate a potential role for melatonin in these time-of-day effects; however the specific underlying mechanisms have not been well characterized. Understanding of these mechanisms may lead to potential novel smoking cessation treatments. Objective Examine the role of melatonin and melatonin receptors in nicotine free choice consumption Methods A two-bottle oral nicotine choice paradigm was utilized with melatonin supplementation in melatonin deficient mice (C57BL/6J) or without melatonin supplementation in mice proficient at melatonin synthesis (C3H/Ibg) compared to melatonin proficient mice lacking both or one of the high affinity melatonin receptors (MT1 and MT2; double null mutant DM, or MT1 or MT2). Preference for bitter and sweet tastants also was assessed in wild type and MT1 and MT2 DM mice. Finally, home cage locomotor monitoring was performed to determine the effect of melatonin administration on activity patterns. Results Supplemental melatonin in drinking water significantly reduced free-choice nicotine consumption in C57BL/6J mice, which do not produce endogenous melatonin, while not altering activity patterns. Independently, genetic deletion of both MT1 and MT2 receptors in a melatonin proficient mouse strain (C3H) resulted in significantly more nicotine consumption than controls. However single genetic deletion of either the MT1 or MT2 receptor alone did not result in increased nicotine consumption. Deletion of MT1 and MT2 did not impact taste preference. Conclusions This study demonstrates that nicotine consumption can be affected by exogenous or endogenous melatonin and requires at least one of the high-affinity melatonin receptors. The fact that expression of either the MT1 or MT2 melatonin receptor is sufficient to maintain lower nicotine consumption suggests functional overlap and

  16. Nicotine inhibits activation of microglial proton currents via interactions with α7 acetylcholine receptors.

    Science.gov (United States)

    Noda, Mami; Kobayashi, A I

    2017-01-01

    Alpha 7 subunits of nicotinic acetylcholine receptors (nAChRs) are expressed in microglia and are involved in the suppression of neuroinflammation. Over the past decade, many reports show beneficial effects of nicotine, though little is known about the mechanism. Here we show that nicotine inhibits lipopolysaccharide (LPS)-induced proton (H+) currents and morphological change by using primary cultured microglia. The H+ channel currents were measured by whole-cell patch clamp method under voltage-clamp condition. Increased H+ current in activated microglia was attenuated by blocking NADPH oxidase. The inhibitory effect of nicotine was due to the activation of α7 nAChR, not a direct action on the H+ channels, because the effects of nicotine was cancelled by α7 nAChR antagonists. Neurotoxic effect of LPS-activated microglia due to inflammatory cytokines was also attenuated by pre-treatment of microglia with nicotine. These results suggest that α7 nAChRs in microglia may be a therapeutic target in neuroinflammatory diseases.

  17. Design, synthesis and biological evaluation of Erythrina alkaloid analogues as neuronal nicotinic acetylcholine receptor antagonists

    DEFF Research Database (Denmark)

    Crestey, François; Jensen, Anders A.; Borch, Morten

    2013-01-01

    The synthesis of a new series of Erythrina alkaloid analogues and their pharmacological characterization at various nicotine acetylcholine receptor (nAChR) subtypes are described. The compounds were designed to be simplified analogues of aromatic erythrinanes with the aim of obtaining subtype-sel...

  18. Conformationally restrained carbamoylcholine homologues. Synthesis, pharmacology at neuronal nicotinic acetylcholine receptors and biostructural considerations

    DEFF Research Database (Denmark)

    de la Fuente Revenga, M; Balle, Thomas; Jensen, Anders A.

    2015-01-01

    Exploration of small selective ligands for the nicotinic acetylcholine receptors (nAChRs) based on acetylcholine (ACh) has led to the development of potent agonists with clear preference for the α4β2 nAChR, the most prevalent nAChR subtype in the central nervous system. In this work we present th...

  19. Synthesis and pharmacological evaluation of DHβE analogs as neuronal nicotinic acetylcholine receptor antagonists

    DEFF Research Database (Denmark)

    Jepsen, Tue H.; Jensen, Anders A.; Lund, Mads Henrik

    2014-01-01

    Dihydro-β-erythroidine (DHβE) is a member of the Erythrina family of alkaloids and a potent competitive antagonist of the α4β2-subtype of the nicotinic acetylcholine receptors (nAChRs). Guided by an X-ray structure of DHβE in complex with an ACh binding protein, we detail the design, synthesis...

  20. Prostate stem cell antigen interacts with nicotinic acetylcholine receptors and is affected in Alzheimer's disease

    DEFF Research Database (Denmark)

    Jensen, Majbrit Myrup; Mikkelsen, Jens D.; Arvaniti, Maria

    2015-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder involving impaired cholinergic neurotransmission and dysregulation of nicotinic acetylcholine receptors (nAChRs). Ly-6/neurotoxin (Lynx) proteins have been shown to modulate cognition and neural plasticity by binding to nAChR subtypes...

  1. Nicotine-induced expression of low-density lipoprotein receptor in oral epithelial cells.

    Directory of Open Access Journals (Sweden)

    Satoshi Ito

    Full Text Available BACKGROUND: Nicotine use is one of the most important risk factors for the development of cardiovascular and periodontal diseases. Numerous reports have suggested the possible contribution of disturbed lipid metabolism for the development of both disease groups. Despite these observations, little is known about the relationship between tobacco smoking and the development of these diseases. Our previous microarray data revealed that nicotine induced low-density lipoprotein receptor (LDLR expression in oral epithelial cells (OECs. The aim of the present study was to confirm nicotine-mediated LDLR induction and to elucidate the signaling mechanisms leading to the augmented expression of LDLR in OECs. METHODS AND RESULTS: LDLR and nicotinic acetylcholine receptor (nAChR subunit expression was detected by real-time PCR. The production of LDLR was demonstrated by immunofluorescence staining. nAChR-mediated LDLR induction was examined by pre-incubation of the cells with its specific inhibitor, α-bungarotoxin (α-BTX. The functional importance of transcription factor specific protein 1 (Sp1 was examined by luciferase assay, mithramycin pre-incubation or by small interfering RNA (siRNA transfection. The specific binding of Sp1 to R3 region of LDLR 5'-untranslated region was demonstrated with electrophoretic mobility shift assay (EMSA and streptavidin-agarose precipitation assay followed by western blotting. The results confirmed that nicotine induced LDLR expression at the transcriptional level. Nicotine was sensed by nAChR and the signal was transduced by Sp1 which bound to the R3 region of LDLR gene. Augmented production of LDLR in the gingival epithelial cells was further demonstrated by immunofluorescence staining using the gingival tissues obtained from the smoking patients. CONCLUSIONS: Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in

  2. Human polymorphisms in nicotinic receptors: a functional analysis in iPS-derived dopaminergic neurons.

    Science.gov (United States)

    Deflorio, Cristina; Blanchard, Stéphane; Carisì, Maria Carla; Bohl, Delphine; Maskos, Uwe

    2017-02-01

    Tobacco smoking is a public health problem, with ∼5 million deaths per year, representing a heavy burden for many countries. No effective therapeutic strategies are currently available for nicotine addiction, and it is therefore crucial to understand the etiological and pathophysiological factors contributing to this addiction. The neuronal α5 nicotinic acetylcholine receptor (nAChR) subunit is critically involved in nicotine dependence. In particular, the human polymorphism α5D398N corresponds to the strongest correlation with nicotine dependence risk found to date in occidental populations, according to meta-analysis of genome-wide association studies. To understand the specific contribution of this subunit in the context of nicotine addiction, an efficient screening system for native human nAChRs is needed. We have differentiated human induced pluripotent stem (iPS) cells into midbrain dopaminergic (DA) neurons and obtained a comprehensive characterization of these neurons by quantitative RT-PCR. The functional properties of nAChRs expressed in these human DA neurons, with or without the polymorphism in the α5 subunit, were studied with the patch-clamp electrophysiological technique. Our results in human DA neurons carrying the polymorphism in the α5 subunit showed an increase in EC50, indicating that, in the presence of the polymorphism, more nicotine or acetylcholine chloride is necessary to obtain the same effect. This human cell culturing system can now be used in drug discovery approaches to screen for compounds that interact specifically with human native and polymorphic nAChRs.-Deflorio, C., Blanchard, S., Carisì, M. C., Bohl, D., Maskos, U. Human polymorphisms in nicotinic receptors: a functional analysis in iPS-derived dopaminergic neurons. © FASEB.

  3. Sex differences and the role of dopamine receptors in the reward-enhancing effects of nicotine and bupropion.

    Science.gov (United States)

    Barrett, Scott T; Geary, Trevor N; Steiner, Amy N; Bevins, Rick A

    2017-01-01

    Nicotine and bupropion have been demonstrated to enhance the value of other reinforcers, and this may partially account for nicotine reward and dependence. Evidence suggests that the sexes differ in their sensitivity to the primary and secondary reinforcing effects of nicotine and nicotine-associated stimuli. Whether the sexes also differ in sensitivity to the reward-enhancing effects of nicotine (and bupropion) is yet unclear. The present study evaluated potential sex differences in the enhancement effects of nicotine and bupropion using a reinforcer demand approach. Furthermore, we sought to investigate the role that D1- and D2-type dopamine receptors play in the reward-enhancing effects of nicotine and bupropion. Demand for sensory reinforcement was assessed in male and female rats responding on a progression of fixed ratio schedules. The effects of nicotine and 10 or 20 mg/kg bupropion on reinforcer demand were assessed within subjects. Subsequently, the effects of SCH-23390 and eticlopride were assessed on the enhancing effects of nicotine and bupropion on progressive ratio responding. Nicotine and bupropion enhanced demand metrics of reinforcement value in both sexes. Females were more sensitive to the enhancement effects of bupropion assessed by reinforcer demand and progressive ratio performance. D2-like dopamine receptor antagonism by eticlopride attenuated the enhancement effects of bupropion, but not of nicotine. Nicotine and bupropion both enhance reinforcement value in both sexes, though females may be more sensitive to the reward-enhancing effects of bupropion. D2- and possibly D1-type receptors appear to be involved in the reward-enhancing effects of bupropion, but not necessarily nicotine.

  4. Nicotinic alpha 7 receptor expression and modulation of the lung epithelial response to lipopolysaccharide.

    Directory of Open Access Journals (Sweden)

    Lorise C Gahring

    Full Text Available Nicotine modulates multiple inflammatory responses in the lung through the nicotinic acetylcholine receptor subtype alpha7 (α7. Previously we reported that α7 modulates both the hematopoietic and epithelium responses in the lung to the bacterial inflammogen, lipopolysaccharide (LPS. Here we apply immunohistochemistry, flow cytometry and RNA-Seq analysis of isolated distal lung epithelium to further define α7-expression and function in this tissue. Mouse lines were used that co-express a bicistronic tau-green fluorescent protein (tGFP as a reporter of α7 (α7G expression and that harbor an α7 with a specific point mutation (α7E260A:G that selectively uncouples it from cell calcium-signaling mechanisms. The tGFP reporter reveals strong cell-specific α7-expression by alveolar macrophages (AM, Club cells and ATII cells. Ciliated cells do not express detectible tGFP, but their numbers decrease by one-third in the α7E260A:G lung compared to controls. Transcriptional comparisons (RNA-Seq between α7G and α7E260A:G enriched lung epithelium 24 hours after challenge with either intra-nasal (i.n. saline or LPS reveals a robust α7-genotype impact on both the stasis and inflammatory response of this tissue. Overall the α7E260A:G lung epithelium exhibits reduced inflammatory cytokine/chemokine expression to i.n. LPS. Transcripts specific to Club cells (e.g., CC10, secretoglobins and Muc5b or to ATII cells (e.g., surfactant proteins were constitutively decreased in in the α7E260A:G lung, but they were strongly induced in response to i.n. LPS. Protein analysis applying immunohistochemistry and ELISA also revealed α7-associated differences suggested by RNA-Seq including altered mucin protein 5b (Muc5b accumulation in the α7E260A:G bronchia, that in some cases appeared to form airway plugs, and a substantial increase in extracellular matrix deposits around α7E260A:G airway bronchia linings that was not seen in controls. Our results show that α7 is

  5. Melatonin administration alters nicotine preference consumption via signaling through high-affinity melatonin receptors.

    Science.gov (United States)

    Horton, William J; Gissel, Hannah J; Saboy, Jennifer E; Wright, Kenneth P; Stitzel, Jerry A

    2015-07-01

    While it is known that tobacco use varies across the 24-h day, the time-of-day effects are poorly understood. Findings from several previous studies indicate a potential role for melatonin in these time-of-day effects; however, the specific underlying mechanisms have not been well characterized. Understanding of these mechanisms may lead to potential novel smoking cessation treatments. The objective of this study is examine the role of melatonin and melatonin receptors in nicotine free-choice consumption A two-bottle oral nicotine choice paradigm was utilized with melatonin supplementation in melatonin-deficient mice (C57BL/6J) or without melatonin supplementation in mice proficient at melatonin synthesis (C3H/Ibg) compared to melatonin-proficient mice lacking both or one of the high-affinity melatonin receptors (MT1 and MT2; double-null mutant DM, or MT1 or MT2). Preference for bitter and sweet tastants also was assessed in wild-type and MT1 and MT2 DM mice. Finally, home cage locomotor monitoring was performed to determine the effect of melatonin administration on activity patterns. Supplemental melatonin in drinking water significantly reduced free-choice nicotine consumption in C57BL/6J mice, which do not produce endogenous melatonin, while not altering activity patterns. Independently, genetic deletion of both MT1 and MT2 receptors in a melatonin-proficient mouse strain (C3H) resulted in significantly more nicotine consumption than controls. However, single genetic deletion of either the MT1 or MT2 receptor alone did not result in increased nicotine consumption. Deletion of MT1 and MT2 did not impact taste preference. This study demonstrates that nicotine consumption can be affected by exogenous or endogenous melatonin and requires at least one of the high-affinity melatonin receptors. The fact that expression of either the MT1 or MT2 melatonin receptor is sufficient to maintain lower nicotine consumption suggests functional overlap and potential mechanistic

  6. Acetylcholine Attenuates Hydrogen Peroxide-Induced Intracellular Calcium Dyshomeostasis Through Both Muscarinic and Nicotinic Receptors in Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Siripong Palee

    2016-06-01

    Full Text Available Background/Aims: Oxidative stress induced intracellular Ca2+ overload plays an important role in the pathophysiology of several heart diseases. Acetylcholine (ACh has been shown to suppress reactive oxygen species generation during oxidative stress. However, there is little information regarding the effects of ACh on the intracellular Ca2+ regulation in the presence of oxidative stress. Therefore, we investigated the effects of ACh applied before or after hydrogen peroxide (H2O2 treatment on the intracellular Ca2+ regulation in isolated cardiomyocytes. Methods: Single ventricular myocytes were isolated from the male Wistar rats for the intracellular Ca2+ transient study by a fluorimetric ratio technique. Results: H2O2 significantly decreased both of intracellular Ca2+ transient amplitude and decay rate. ACh applied before, but not after, H2O2 treatment attenuated the reduction of intracellular Ca2+ transient amplitude and decay rate. Both atropine (a muscarinic acetylcholine receptor blocker and mecamylamine (a nicotinic acetylcholine receptor blocker significantly decreased the protective effects of acetylcholine on the intracellular Ca2+ regulation. Moreover, the combination of atropine and mecamylamine completely abolished the protective effects of acetylcholine on intracellular Ca2+ transient amplitude and decay rate. Conclusion: ACh pretreatment attenuates H2O2-induced intracellular Ca2+ dyshomeostasis through both muscarinic and nicotinic receptors.

  7. Nootropic α7 nicotinic receptor allosteric modulator derived from GABAA receptor modulators

    Science.gov (United States)

    Ng, Herman J.; Whittemore, Edward R.; Tran, Minhtam B.; Hogenkamp, Derk J.; Broide, Ron S.; Johnstone, Timothy B.; Zheng, Lijun; Stevens, Karen E.; Gee, Kelvin W.

    2007-01-01

    Activation of brain α7 nicotinic acetylcholine receptors (α7 nAChRs) has broad therapeutic potential in CNS diseases related to cognitive dysfunction, including Alzheimer's disease and schizophrenia. In contrast to direct agonist activation, positive allosteric modulation of α7 nAChRs would deliver the clinically validated benefits of allosterism to these indications. We have generated a selective α7 nAChR-positive allosteric modulator (PAM) from a library of GABAA receptor PAMs. Compound 6 (N-(4-chlorophenyl)-α-[[(4-chloro-phenyl)amino]methylene]-3-methyl-5-isoxazoleacet-amide) evokes robust positive modulation of agonist-induced currents at α7 nAChRs, while preserving the rapid native characteristics of desensitization, and has little to no efficacy at other ligand-gated ion channels. In rodent models, it corrects sensory-gating deficits and improves working memory, effects consistent with cognitive enhancement. Compound 6 represents a chemotype for allosteric activation of α7 nAChRs, with therapeutic potential in CNS diseases with cognitive dysfunction. PMID:17470817

  8. Stress induces behavioral sensitization, increases nicotine-seeking behavior and leads to a decrease of CREB in the nucleus accumbens.

    Science.gov (United States)

    Leão, Rodrigo Molini; Cruz, Fábio Cardoso; Marin, Marcelo Tadeu; Planeta, Cleopatra da Silva

    2012-05-01

    Experimental evidence shows that exposure to stress engenders behavioral sensitization and increases drug-seeking and leads to intense drug taking. However the molecular mechanisms involved in these processes is not well known yet. The present experiments examined the effects of exposure to variable stress on nicotine-induced locomotor activation, cAMP-response element-binding protein (CREB) and extracellular signal-regulated kinase (ERK) activity and nicotine intravenous self-administration in rats. Male Wistar rats were exposed to variable stress that consisted of the exposure to different stressors twice a day in random order for 10 days. During this period the control group was left undisturbed except for cage cleaning. Ten days after the last stress episode, rats were challenged with either saline or nicotine (0.4 mg/kgs.c.) and the locomotor activity was recorded for 20 min. Immediately after behavioral recordings rats were sacrificed and their brains were removed to posterior western blotting analysis of CREB, phosphoCREB, ERK and phosphoERK in the nucleus accumbens. An independent set of control and stressed animals were subjected to an intravenous nicotine self-administration protocol. The break point during a progressive ratio schedule and nicotine intake patterns during a 24-hour binge was analyzed. Repeated variable stress caused a sensitized motor response to a single challenge of nicotine and decreased CREB in the nucleus accumbens. Furthermore, in the self-administration experiments previous stress exposure caused an increase in the break point and nicotine intake. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Neuronal nicotinic acetylcholine receptors are important targets for alcohol reward and dependence.

    Science.gov (United States)

    Wu, Jie; Gao, Ming; Taylor, Devin H

    2014-03-01

    Neuronal nicotinic acetylcholine receptors are important targets for alcohol reward and dependence. Alcoholism is a serious public health problem and has been identified as the third major cause of preventable mortality in the world. Worldwide, about 2 billion people consume alcohol, with 76.3 million having diagnosable alcohol use disorders. Alcohol is currently responsible for the death of 4% of adults worldwide (about 2.5 million deaths each year), and this number will be significantly increased by 2020 unless effective action is taken. Alcohol is the most commonly abused substance by humans. Ethanol (EtOH) is the intoxicating agent in alcoholic drinks that can lead to abuse and dependence. Although it has been extensively studied, the mechanisms of alcohol reward and dependence are still poorly understood. The major reason is that, unlike other addictive drugs (eg, morphine, cocaine or nicotine) that have specific molecular targets, EtOH affects much wider neuronal functions. These functions include phospholipid membranes, various ion channels and receptors, synaptic and network functions, and intracellular signaling molecules. The major targets in the brain that mediate EtOH's effects remain unclear. This knowledge gap results in a therapeutic barrier in the treatment of alcoholism. Interestingly, alcohol and nicotine are often co-abused, which suggests that neuronal nicotinic acetylcholine receptors (nAChRs), the molecular targets for nicotine, may also contribute to alcohol's abusive properties. Here, we briefly summarize recent lines of evidence showing how EtOH modulates nAChRs in the mesolimbic pathway, which provides a perspective that nAChRs are important targets mediating alcohol abuse.

  10. The Role of Nicotinic Acetylcholine Receptors in the Medial Prefrontal Cortex and Hippocampus in Trace Fear Conditioning

    Science.gov (United States)

    Raybuck, J. D.; Gould, T. J.

    2010-01-01

    Acute nicotine enhances multiple types of learning including trace fear conditioning but the underlying neural substrates of these effects are not well understood. Trace fear conditioning critically involves the medial prefrontal cortex and hippocampus, which both express nicotinic acetylcholine receptors (nAChRs). Therefore, nicotine could act in either or both areas to enhance trace fear conditioning. To identify the underlying neural areas and nAChR subtypes, we examined the effects of infusion of nicotine, or nicotinic antagonists dihydro-beta-erythroidine (DHβE: high-affinity nAChRs) or methyllycaconitine (MLA: low-affinity nAChRs) into the dorsal hippocampus, ventral hippocampus, and medial prefrontal cortex (mPFC) on trace and contextual fear conditioning. We found that the effects of nicotine on trace and contextual fear conditioning vary by brain region and nAChR subtype. The dorsal hippocampus was involved in the effects of nicotine on both trace and contextual fear conditioning but each task was sensitive to different doses of nicotine. Additionally, dorsal hippocampal infusion of the antagonist DHβE produced deficits in trace but not contextual fear conditioning. Nicotine infusion into the ventral hippocampus produced deficits in both trace and contextual fear conditioning. In the mPFC, nicotine enhanced trace but not contextual fear conditioning. Interestingly, infusion of the antagonists MLA or DHβE in the mPFC also enhanced trace fear conditioning. These findings suggest that nicotine acts on different substrates to enhance trace versus contextual fear conditioning, and that nicotine-induced desensitization of nAChRs in the mPFC may contribute to the effects of nicotine on trace fear conditioning. PMID:20727979

  11. Use of Monoclonal Antibodies to Study the Structural Basis of the Function of Nicotinic Acetylcholine Receptors on Electric Organ and Muscle and to Determine the Structure of Nicotinic Acetylcholine Receptors on Neurons

    Science.gov (United States)

    1989-09-30

    of chicken neurona .4receptor subunits. Sequences of al and a2 are from Net .Ot al. -l Sequences of a3 and a4 were determintl from clones described...Sucrose gradient analysis of neurona & nicotinic receptors was conducted as follows. Chicken ind rat brain receptors were extracted from crude

  12. Comparative distribution of nicotinic receptor subtypes during development, adulthood and aging: an autoradiographic study in the rat brain.

    Science.gov (United States)

    Tribollet, E; Bertrand, D; Marguerat, A; Raggenbass, M

    2004-01-01

    The distribution in the rat brain of high affinity nicotinic heteromeric acetylcholine receptors and of low affinity nicotinic, alpha7-containing, homomeric receptors was studied using in vitro light microscopic autoradiography. As ligands, we used [3H]epibatidine, or [125I]epibatidine, and [125I]alpha-bungarotoxin, respectively. In adult animals, the two types of binding sites were widely distributed in many different brain structures, including the brainstem, cerebellum, mesencephalic structures, limbic system and cortex, but their anatomical distribution differed markedly. Only in rare instances could a co-localization be observed, for example in the superficial layer of the superior colliculus. In developing animals, both types of labeling were strongly expressed during embryonic and postnatal phases. Their distributions were qualitatively similar to those observed in adult animals, with a few noticeable exceptions in the cerebral cortex, hippocampus and brain stem. In aging animals, neither the distribution nor the density of nicotinic binding sites was significantly altered. Our conclusions are the following. (a) There is little overlap in the distribution of heteromeric and alpha7-containing homomeric nicotinic receptors in the rat brain. (b) The abundance of neuronal nicotinic receptors during embryonic and postnatal development suggests that they may play a role in the establishment of neuronal connectivity. (c) The expression of neuronal nicotinic receptors is unaltered in middle aged animals, suggesting that in the rat these receptors do not play any major role in aging process.

  13. State of the art on insect nicotinic acetylcholine receptor function in learning and memory.

    Science.gov (United States)

    Gauthier, Monique

    2010-01-01

    Acetylcholine is the most abundant excitatory neurotransmitter in the insect brain and the most numerous acetylcholine receptors are the nicotinic ones (nAChRs). The genome sequencing of diverse insect species has demonstrated the existence of at least 10 nAChR genes coding for alpha and beta subunits, suggesting the existence in the insect CNS of several subtypes ofnAChRs whose molecular composition and pharmacological properties are still unknown. Insect nAChRs have given rise to an abundance of literature about their sensitivity to neonicotinoid insecticides but only limited data are available on the functional role of nAChRs in insect cognitive functions. The data we have collected on honeybees are the only data that shed light on the role of nAChRs in learning and memory processes. The behavioral response of proboscis extension (PER), which appears when the honeybee perceives sugar, was used to quantify learning and memory performances in associative and non-associative learning procedures. Habituation of the PER, which consists in ceasing to respond to sucrose upon repetitive antennal sucrose stimulation, was facilitated by the injection into the brain of one of the nicotinic antagonists mecamylamine, alpha-bungarotoxin (alpha-BGT) or methyllycaconitine (MLA). Pavlovian associative protocol was used to condition the PER to olfactory or tactile stimulus after single- or multiple-trial training. Localized brain injections of the nicotinic antagonist mecamylamine were performed before or after one-trial olfactory learning in the mushroom bodies (MB), the integrative structures of the insect brain. The results showed that the calical input structures of the MB are necessary for the acquisition processes and the output a-lobe regions are involved in retrieval processes. Brain injection of one of the three nicotinic antagonists mecamylamine, alpha-BGT and MLA was combined with single- and multiple-trial olfactory and tactile learning and memory performances were

  14. Effects of the histamine H₃ receptor antagonist ABT-239 on cognition and nicotine-induced memory enhancement in mice.

    Science.gov (United States)

    Kruk, Marta; Miszkiel, Joanna; McCreary, Andrew C; Przegaliński, Edmund; Filip, Małgorzata; Biała, Grażyna

    2012-01-01

    The strong correlation between central histaminergic and cholinergic pathways on cognitive processes has been reported extensively. However, the role of histamine H(3) receptor mechanisms interacting with nicotinic mechanisms has not previously been extensively investigated. The current study was conducted to determine the interactions of nicotinic and histamine H(3) receptor systems with regard to learning and memory function using a modified elevated plus-maze test in mice. In this test, the latency for mice to move from the open arm to the enclosed arm (i.e., transfer latency) was used as an index of memory. We tested whether ABT-239 (4-(2-{2-[(2R)-2-methylpyrrolidinyl]ethyl}-benzofuran-5-yl), an H(3) receptor antagonist/inverse agonist, had influence on two different stages of memory, i.e., memory acquisition and consolidation (administered prior to or immediately after the first trial, respectively) and whether ABT-239 influenced nicotine-induced memory enhancement. Our results revealed that the acute administration of nicotine (0.035 and 0.175 mg/kg), but not of ABT-239 (0.1-3 mg/kg) reduced transfer latency in the acquisition and consolidation phases. In combination studies, concomitant administration of either ABT-239 (1 and 3 mg/kg) and nicotine (0.035 mg/kg), or ABT-239 (0.1 mg/kg) and nicotine (0.0175 mg/kg) further increased nicotine-induced improvement in both memory acquisition and consolidation. The present data confirm an important role for H(3) receptors in regulating nicotine-induced mnemonic effects since inhibition of H(3) receptors augmented nicotine-induced memory enhancement in mice.

  15. Inhibition of human α7 nicotinic acetylcholine receptors by cyclic monoterpene carveol.

    Science.gov (United States)

    Lozon, Yosra; Sultan, Ahmed; Lansdell, Stuart J; Prytkova, Tatiana; Sadek, Bassem; Yang, Keun-Hang Susan; Howarth, Frank Christopher; Millar, Neil S; Oz, Murat

    2016-04-05

    Cyclic monoterpenes are a group of phytochemicals with antinociceptive, local anesthetic, and anti-inflammatory actions. Effects of cyclic monoterpenes including vanilin, pulegone, eugenole, carvone, carvacrol, carveol, thymol, thymoquinone, menthone, and limonene were investigated on the functional properties of the cloned α7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes. Monoterpenes inhibited the α7 nicotinic acetylcholine receptor in the order carveol>thymoquinone>carvacrol>menthone>thymol>limonene>eugenole>pulegone≥carvone≥vanilin. Among the monoterpenes, carveol showed the highest potency on acetylcholine-induced responses, with IC50 of 8.3µM. Carveol-induced inhibition was independent of the membrane potential and could not be reversed by increasing the concentration of acetylcholine. In line with functional experiments, docking studies indicated that cyclic monoterpenes such as carveol may interact with an allosteric site located in the α7 transmembrane domain. Our results indicate that cyclic monoterpenes inhibit the function of human α7 nicotinic acetylcholine receptors, with varying potencies. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Deletion of lynx1 reduces the function of α6* nicotinic receptors.

    Directory of Open Access Journals (Sweden)

    Rell L Parker

    Full Text Available The α6 nicotinic acetylcholine receptor (nAChR subunit is an attractive drug target for treating nicotine addiction because it is present at limited sites in the brain including the reward pathway. Lynx1 modulates several nAChR subtypes; lynx1-nAChR interaction sites could possibly provide drug targets. We found that dopaminergic cells from the substantia nigra pars compacta (SNc express lynx1 mRNA transcripts and, as assessed by co-immunoprecipitation, α6 receptors form stable complexes with lynx1 protein, although co-transfection with lynx1 did not affect nicotine-induced currents from cell lines transfected with α6 and β2. To test whether lynx1 is important for the function of α6 nAChRs in vivo, we bred transgenic mice carrying a hypersensitive mutation in the α6 nAChR subunit (α6L9'S with lynx1 knockout mice, providing a selective probe of the effects of lynx1 on α6* nAChRs. Lynx1 removal reduced the α6 component of nicotine-mediated rubidium efflux and dopamine (DA release from synaptosomal preparations with no effect on numbers of α6β2 binding sites, indicating that lynx1 is functionally important for α6* nAChR activity. No effects of lynx1 removal were detected on nicotine-induced currents in slices from SNc, suggesting that lynx1 affects presynaptic α6* nAChR function more than somatic function. In the absence of agonist, lynx1 removal did not alter DA release in dorsal striatum as measured by fast scan cyclic voltammetry. Lynx1 removal affected some behaviors, including a novel-environment assay and nicotine-stimulated locomotion. Trends in 24-hour home-cage behavior were also suggestive of an effect of lynx1 removal. Conditioned place preference for nicotine was not affected by lynx1 removal. The results show that some functional and behavioral aspects of α6-nAChRs are modulated by lynx1.

  17. Menthol Suppresses Nicotinic Acetylcholine Receptor Functioning in Sensory Neurons via Allosteric Modulation

    Science.gov (United States)

    Wilhelm, M.; Swandulla, D.

    2012-01-01

    In this study, we have investigated how the function of native and recombinant nicotinic acetylcholine receptors (nAChRs) is modulated by the monoterpenoid alcohol from peppermint (−) menthol. In trigeminal neurons (TG), we found that nicotine (75 μM)-activated whole-cell currents through nAChRs were reversibly reduced by menthol in a concentration-dependent manner with an IC50 of 111 μM. To analyze the mechanism underlying menthol's action in more detail, we used single channel and whole-cell recordings from recombinant human α4β2 nAChR expressed in HEK tsA201 cells. Here, we found a shortening of channel open time and a prolongation of channel closed time, and an increase in single channel amplitude leading in summary to a reduction in single channel current. Furthermore, menthol did not affect nicotine's EC50 value for currents through recombinant human α4β2 nAChRs but caused a significant reduction in nicotine's efficacy. Taken together, these findings indicate that menthol is a negative allosteric modulator of nAChRs. PMID:22281529

  18. Alpha7-nicotinic acetylcholine receptors affect growth regulation of human mesothelioma cells: role of mitogen-activated protein kinase pathway.

    Science.gov (United States)

    Trombino, Sonya; Cesario, Alfredo; Margaritora, Stefano; Granone, PierLuigi; Motta, Giovanni; Falugi, Carla; Russo, Patrizia

    2004-01-01

    This study presents data suggesting that both human mesothelioma (cell lines and human mesothelioma biopsies) and human normal mesothelial cells express receptors for acetylcholine and that stimulation of these receptors by nicotine prompted cell growth via activation of nicotinic cholinergic receptors. Thus, these data demonstrate that: (a) human mesothelioma cells and human biopsies of mesothelioma as well as of normal pleural mesothelial cells express functionally alpha-7 nicotinic acethlycholine receptors, evaluated by alpha-bungarotoxin-FITC binding, receptor binding assay, Western blot, and reverse transcription-PCR; (b) choline acetyltransferase immunostaining is present in mesothelioma cells; (c) mesothelioma cell growth is modulated by the cholinergic system in which agonists (i.e., nicotine) has a proliferative effect, and antagonists (i.e., curare) has an inhibitory effect, evaluated by cell cloning, DNA synthesis and cell cycle; (d) nicotine induces Ca(+2) influx, evaluated by [(45)Ca(2+)] uptake, and consequently activation of mitogen-activated protein kinase pathway (extracellular signal-regulated kinase and p90(RSK) phosphorylation), evaluated by Western blot; and (e) apoptosis mechanisms in mesothelioma cells are under the control of the cholinergic system (nicotine antiapoptotic via induction of nuclear factor-kappaB complexes and phosphorylation of Bad at Ser(112); curare proapoptotic via G(0)-G(1) arrest p21(waf-1) dependent but p53 independent). The involvement of the nonneuronal cholinergic system in mesothelioma appears reasonable and open up new therapeutic strategies.

  19. A new IRAK-M-mediated mechanism implicated in the anti-inflammatory effect of nicotine via α7 nicotinic receptors in human macrophages.

    Directory of Open Access Journals (Sweden)

    Maria C Maldifassi

    Full Text Available Nicotine stimulation of α7 nicotinic acetylcholine receptor (α7 nAChR powerfully inhibits pro-inflammatory cytokine production in lipopolysaccharide (LPS-stimulated macrophages and in experimental models of endotoxemia. A signaling pathway downstream from the α7 nAChRs, which involves the collaboration of JAK2/STAT3 and NF-κB to interfere with signaling by Toll-like receptors (TLRs, has been implicated in this anti-inflammatory effect of nicotine. Here, we identifiy an alternative mechanism involving interleukin-1 receptor-associated kinase M (IRAK-M, a negative regulator of innate TLR-mediated immune responses. Our data show that nicotine up-regulates IRAK-M expression at the mRNA and protein level in human macrophages, and that this effect is secondary to α7 nAChR activation. By using selective inhibitors of different signaling molecules downstream from the receptor, we provide evidence that activation of STAT3, via either JAK2 and/or PI3K, through a single (JAK2/PI3K/STAT3 or two convergent cascades (JAK2/STAT3 and PI3K/STAT3, is necessary for nicotine-induced IRAK-M expression. Moreover, down-regulation of this expression by small interfering RNAs specific to the IRAK-M gene significantly reverses the anti-inflammatory effect of nicotine on LPS-induced TNF-α production. Interestingly, macrophages pre-exposed to nicotine exhibit higher IRAK-M levels and reduced TNF-α response to an additional LPS challenge, a behavior reminiscent of the 'endotoxin tolerant' phenotype identified in monocytes either pre-exposed to LPS or from immunocompromised septic patients. Since nicotine is a major component of tobacco smoke and increased IRAK-M expression has been considered one of the molecular determinants for the induction of the tolerant phenotype, our findings showing IRAK-M overexpression could partially explain the known influence of smoking on the onset and progression of inflammatory and infectious diseases.

  20. Bimodal concentration-response of nicotine involves the nicotinic acetylcholine receptor, transient receptor potential vanilloid type 1, and transient receptor potential ankyrin 1 channels in mouse trachea and sensory neurons.

    Science.gov (United States)

    Kichko, Tatjana I; Lennerz, Jochen; Eberhardt, Mirjam; Babes, Ramona M; Neuhuber, Winfried; Kobal, Gerd; Reeh, Peter W

    2013-11-01

    High concentrations of nicotine, as in the saliva of oral tobacco consumers or in smoking cessation aids, have been shown to sensitize/activate recombinant transient receptor potential vanilloid type 1 (rTRPV1) and mouse TRPA1 (mTRPA1) channels. By measuring stimulated calcitonin gene-related peptide (CGRP) release from the isolated mouse trachea, we established a bimodal concentration-response relationship with a threshold below 10 µM (-)-nicotine, a maximum at 100 µM, an apparent nadir between 0.5 and 10 mM, and a renewed increase at 20 mM. The first peak was unchanged in TRPV1/A1 double-null mutants as compared with wild-types and was abolished by specific nicotinic acetylcholine receptor (nAChR) inhibitors and by camphor, discovered to act as nicotinic antagonist. The nicotine response at 20 mM was strongly pHe-dependent, - five times greater at pH 9.0 than 7.4, indicating that intracellular permeation of the (uncharged) alkaloid was required to reach the TRPV1/A1 binding sites. The response was strongly reduced in both null mutants, and more so in double-null mutants. Upon measuring calcium transients in nodose/jugular and dorsal root ganglion neurons in response to 100 µM nicotine, 48% of the vagal (but only 14% of the somatic) sensory neurons were activated, the latter very weakly. However, nicotine 20 mM at pH 9.0 repeatedly activated almost every single cultured neuron, partly by releasing intracellular calcium and independent of TRPV1/A1 and nAChRs. In conclusion, in mouse tracheal sensory nerves nAChRs are 200-fold more sensitive to nicotine than TRPV1/A1; they are widely coexpressed with the capsaicin receptor among vagal sensory neurons and twice as abundant as TRPA1. Nicotine is the major stimulant in tobacco, and its sensory impact through nAChRs should not be disregarded.

  1. Heteromeric α7β2 Nicotinic Acetylcholine Receptors in the Brain

    DEFF Research Database (Denmark)

    Wu, Jie; Liu, Qiang; Tang, Pei

    2016-01-01

    The α7 nicotinic acetylcholine receptor (α7 nAChR) is highly expressed in the brain, where it maintains various neuronal functions including (but not limited to) learning and memory. In addition, the protein expression levels of α7 nAChRs are altered in various brain disorders. The classic rule...... governing α7 nAChR assembly in the mammalian brain was that it was assembled from five α7 subunits to form a homomeric receptor pentamer. However, emerging evidence demonstrates the presence of heteromeric α7 nAChRs in heterologously expressed systems and naturally in brain neurons, where α7 subunits are co...

  2. Therapeutic potential of α7 nicotinic receptor agonists to regulate neuroinflammation in neurodegenerative diseases

    Science.gov (United States)

    Foucault-Fruchard, Laura; Antier, Daniel

    2017-01-01

    Neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's diseases, are all characterized by a component of innate immunity called neuroinflammation. Neuronal loss and neuroinflammation are two phenomena closely linked. Hence, the neuroinflammation is a relevant target for the management of the neurodegenerative diseases given that, to date, there is no treatment to stop neuronal loss. Several studies have investigated the potential effects of activators of alpha 7 nicotinic acetylcholine receptors in animal models of neurodegenerative diseases. These receptors are widely distributed in the central nervous system. After activation, they seem to mediate the cholinergic anti-inflammatory pathway in the brain. This anti-inflammatory pathway, first described in periphery, regulates activation of microglial cells considered as the resident macrophage population of the central nervous system. In this article, we shortly review the agonists of the alpha 7 nicotinic acetylcholine receptors that have been evaluated in vivo and we focused on the selective positive allosteric modulators of these receptors. These compounds represent a key element to enhance receptor activity only in the presence of the endogenous agonist. PMID:29089979

  3. Therapeutic potential of α7 nicotinic receptor agonists to regulate neuroinflammation in neurodegenerative diseases

    Directory of Open Access Journals (Sweden)

    Laura Foucault-Fruchard

    2017-01-01

    Full Text Available Neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's diseases, are all characterized by a component of innate immunity called neuroinflammation. Neuronal loss and neuroinflammation are two phenomena closely linked. Hence, the neuroinflammation is a relevant target for the management of the neurodegenerative diseases given that, to date, there is no treatment to stop neuronal loss. Several studies have investigated the potential effects of activators of alpha 7 nicotinic acetylcholine receptors in animal models of neurodegenerative diseases. These receptors are widely distributed in the central nervous system. After activation, they seem to mediate the cholinergic anti-inflammatory pathway in the brain. This anti-inflammatory pathway, first described in periphery, regulates activation of microglial cells considered as the resident macrophage population of the central nervous system. In this article, we shortly review the agonists of the alpha 7 nicotinic acetylcholine receptors that have been evaluated in vivo and we focused on the selective positive allosteric modulators of these receptors. These compounds represent a key element to enhance receptor activity only in the presence of the endogenous agonist.

  4. Varenicline provokes impulsive action by stimulating α4β2 nicotinic acetylcholine receptors in the infralimbic cortex in a nicotine exposure status-dependent manner.

    Science.gov (United States)

    Ohmura, Yu; Sasamori, Hitomi; Tsutsui-Kimura, Iku; Izumi, Takeshi; Yoshida, Takayuki; Yoshioka, Mitsuhiro

    2017-03-01

    Higher impulsivity is a risk factor for criminal involvement and drug addiction. Because nicotine administration enhances impulsivity, the effects of stop-smoking aids stimulating nicotinic acetylcholine receptors (nAChRs) on impulsivity must be determined in different conditions. Our goals were 1) to confirm the relationship between varenicline, a stop-smoking aid and α4β2 nAChR partial agonist, and impulsivity, 2) to elucidate the mechanisms underlying the effects of varenicline, 3) to examine whether a low dose of varenicline that does not evoke impulsive action could block the stimulating effects of nicotine on impulsive action, 4) to determine whether the route of administration could modulate the effects of varenicline on impulsive action, and 5) to determine whether the effects of varenicline on impulsivity could be altered by smoking status. We used a 3-choice serial reaction time task to assess impulsivity and other cognitive functions in rats. Our findings are as follows: 1) acute subcutaneous (s.c.) injection of varenicline evoked impulsive action in a dose-dependent manner; 2) the effects of varenicline on impulsivity were blocked by the microinjection of dihydro-β-erythroidine, a α4β2 nAChR antagonist, into the infralimbic cortex; 3) the low dose of varenicline did not attenuate the effects of nicotine on impulsive action at all; 4) oral administration of varenicline evoked impulsive action in a similar manner to s.c. injection; and 5) the stimulating effects of varenicline on impulsive action were not observed in rats that received nicotine infusion for 8days or nicotine-abstinent rats after discontinuing infusion. Additionally, we found that oral varenicline administration enhanced attentional function whether nicotine was infused or not. Thus, although varenicline administration could be harmless to heavy smokers or ex-smokers, it could be difficult for non-smokers with respect to impulsivity, whereas it may be beneficial with respect to

  5. Nicotine Effects and Receptor Expression on Human Spermatozoa: Possible Neuroendocrine Mechanism

    Science.gov (United States)

    Condorelli, Rosita A.; La Vignera, Sandro; Giacone, Filippo; Iacoviello, Linda; Mongioì, Laura M.; Li Volti, Giovanni; Barbagallo, Ignazio; Avola, Roberto; Calogero, Aldo E.

    2017-01-01

    The aim of this experimental study was to investigate the mechanism by which nicotine (NIC) alters spermatozoa and to evaluate the expression of nicotinic receptors (nAChR) subunits in human spermatozoa. We analyzed 30 healthy normozoospermic men. Spermatozoa were incubated with NIC 100 ng/ml and the nAChR antagonist, hexamethonium (HEX) (0, 100, 1,000, 10,000 ng/ml) for 3 and 24 h. The following sperm parameters evaluated: (a) progressive motility; (b) mitochondrial membrane potential (MMP); (c) chromatin compactness; (d) externalization of phosphatidylserine (PS); (e) late apoptosis; (f) viability; (g) DNA fragmentation; (h) degree of lipid peroxidation (LP) by flow cytometry; (i) nAChR subunits expression by quantitative Real Time PCR and (j) protein expression evaluation by Western blot analysis. HEX fully antagonized the effects of NIC both after 3 and 24 h of incubation with significant improvement (p NIC in raw semen but this effect was fully antagonized (p NIC on sperm function are mediated by interaction with a specific nicotinic receptor. The presence of nAChR subunits suggests the presence of a neuroendocrine mechanism on human spermatozoa. PMID:28400736

  6. Recent Advances in Nicotinic Receptor Signaling in Alcohol Abuse and Alcoholism.

    Science.gov (United States)

    Rahman, Shafiqur; Engleman, Eric A; Bell, Richard L

    2016-01-01

    Alcohol is the most commonly abused legal substance and alcoholism is a serious public health problem. It is a leading cause of preventable death in the world. The cellular and molecular mechanisms of alcohol reward and addiction are still not well understood. Emerging evidence indicates that unlike other drugs of abuse, such as nicotine, cocaine, or opioids, alcohol targets numerous channel proteins, receptor molecules, and signaling pathways in the brain. Previously, research has identified brain nicotinic acetylcholine receptors (nAChRs), a heterogeneous family of pentameric ligand-gated cation channels expressed in the mammalian brain, as critical molecular targets for alcohol abuse and dependence. Genetic variations encoding nAChR subunits have been shown to increase the vulnerability to develop alcohol dependence. Here, we review recent insights into the rewarding effects of alcohol, as they pertain to different nAChR subtypes, associated signaling molecules, and pathways that contribute to the molecular mechanisms of alcoholism and/or comorbid brain disorders. Understanding these cellular changes and molecular underpinnings may be useful for the advancement of brain nicotinic-cholinergic mechanisms, and will lead to a better translational and therapeutic outcome for alcoholism and/or comorbid conditions. Copyright © 2016. Published by Elsevier Inc.

  7. Cerebellar nicotinic cholinergic receptors are intrinsic to the cerebellum: implications for diverse functional roles.

    Science.gov (United States)

    Turner, Jill R; Ortinski, Pavel I; Sherrard, Rachel M; Kellar, Kenneth J

    2011-12-01

    Although recent studies have delineated the specific nicotinic subtypes present in the mammalian cerebellum, very little is known about their location or function within the cerebellum. This is of increased interest since nicotinic receptors (nAChRs) in the cerebellum have recently been implicated in the pathology of autism spectrum disorders. To begin to better understand the roles of these heteromeric nAChRs in the cerebellar circuitry and their therapeutic potential as targets for drug development, we used various chemical and stereotaxic lesion models in conjunction with slice electrophysiology to examine how specific heteromeric nAChR subtypes may influence the surrounding cerebellar circuitry. Using subunit-specific immunoprecipitation of radiolabeled nAChRs in the cerebella following N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride, p-chloroamphetamine, and pendunculotomy lesions, we show that most, if not all, cerebellar nicotinic receptors are present in cells within the cerebellum itself and not in extracerebellar afferents. Furthermore, we demonstrate that the β4-containing, but not the β2-containing, nAChRs intrinsic to the cerebellum can regulate inhibitory synaptic efficacy at two major classes of cerebellar neurons. These tandem findings suggest that nAChRs may present a potential drug target for disorders involving the cerebellum.

  8. Pemphigus vulgaris antibodies target the mitochondrial nicotinic acetylcholine receptors that protect keratinocytes from apoptolysis.

    Science.gov (United States)

    Chernyavsky, Alex; Chen, Yumay; Wang, Ping H; Grando, Sergei A

    2015-11-01

    The mechanism of detachment and death of keratinocytes in pemphigus vulgaris (PV) involves pro-apoptotic action of constellations of autoantibodies determining disease severity and response to treatment. The presence of antibodies to nicotinic acetylcholine receptors (nAChRs) and the therapeutic efficacy of cholinomimetics in PV is well-established. Recently, adsorption of anti-mitochondrial antibodies abolished the ability of PVIgGs to cause acantholysis, demonstrating their pathophysiological significance. Since, in addition to cell membrane, nAChRs are also present on the mitochondrial outer membrane, wherein they act to prevent activation of intrinsic (mitochondrial apoptosis), we hypothesized that mitochondrial (mt)-nAChRs might be targeted by PVIgGs. To test this hypothesis, we employed the immunoprecipitation-western blot assay of keratinocyte mitochondrial proteins that visualized the α3, α5, α7, α9, α10, β2 and β4 mt-nAChR subunits precipitated by PV IgGs, suggesting that functions of mt-nAChRs are compromised in PV. To pharmacologically counteract the pro-apoptotic action of anti-mitochondrial antibodies in PV, we exposed naked keratinocyte mitochondria to PVIgGs in the presence of the nicotinic agonist nicotine ± antagonists, and measured cytochrome c (CytC) release. Nicotine abolished PVIgG-dependent CytC release, showing a dose-dependent effect, suggesting that protection of mitochondria can be a novel mechanism of therapeutic action of nicotinic agonists in PV. The obtained results indicated that the mt-nAChRs targeted by anti-mitochondrial antibodies produced by PV patients are coupled to inhibition of CytC release, and that nicotinergic stimulation can abolish PVIgG-dependent activation of intrinsic apoptosis in KCs. Future studies should determine if and how the distinct anti-mt-nAChR antibodies penetrate KCs and correlate with disease severity. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Orthosteric and Allosteric Ligands of Nicotinic Acetylcholine Receptors for Smoking Cessation

    Directory of Open Access Journals (Sweden)

    Tasnim S. Mohamed

    2015-11-01

    Full Text Available Nicotine addiction, the result of tobacco use, leads to over six million premature deaths world-wide, a number that is expected to increase by a third within the next two decades. While more than half of smokers want and attempt to quit, only a small percentage of smokers are able to quit without pharmacological interventions. Therefore, over the past decades, researchers in academia and the pharmaceutical industry have focused their attention on the development of more effective smoking cessation therapies, which is now a growing 1.9 billion dollar market. Because the role of neuronal nicotinic acetylcholine receptors (nAChR in nicotine addiction is well established, nAChR based therapeutics remain the leading strategy for smoking cessation. However, the development of neuronal nAChR drugs that are selective for a nAChR subpopulation is challenging, and only few neuronal nAChR drugs are clinically available. Among the many neuronal nAChR subtypes that have been identified in the brain, the α4β2 subtype is the most abundant and plays a critical role in nicotine addiction. Here, we review the role of neuronal nAChRs, especially the α4β2 subtype, in the development and treatment of nicotine addiction. We also compare available smoking cessation medications and other nAChR orthosteric and allosteric ligands that have been developed with emphasis on the difficulties faced in the development of clinically useful compounds with high nAChR subtype selectivity.

  10. D{sub 2} dopamine receptor gene and behavioral characteristics in nicotine dependence

    Energy Technology Data Exchange (ETDEWEB)

    Noble, E.P.; Fitch, R.J.; Syndulko, K. [Univ. of California, Los Angeles, CA (United States)] [and others

    1994-09-01

    The D{sub 2} dopamine receptor (DRD2) A1 allele has been recently associated with nicotine dependence. In the present study, TaqI A alleles (the minor A1 and the major A2 allele) of the DRD2 were determined in medically-ill subjects. The sample was composed of 41 non-smokers (N), 69 ex-smokers (X) and 63 active smokers (A). The relationships of DRD2 alleles to personality (Eysenick`s Addictive Personality [AP]), depression and nicotine dependence (Fagerstroem) scores were ascertained. A significant (P = 0.002) group effect prevailed in the AP scores, with the A group having the highest scores. Moreover, a significant (P = 0.025) allele by group interaction was found, with A1 allelic subjects in group A showing the highest AP scores. Significant group effects were also found in both the depression (P = 0.0004) and the nicotine dependence (P = 0.0003) scores, with the A group again showing the highest scores. However, in contrast to the AP scores, no significant allele by group interaction was found either in the depression or the nicotine dependence scores. In conclusion, the present findings suggest a role for the DRD2 gene in personality of smokers. However, relationship of the DRD2 gene to the degree of depression or nicotine dependence was not found. The data indicate the importance of using behavioral and genetic variables in dissecting the complex set of variables associated with the smoking habit, and thus in achieving a better understanding of the biobehavioral bases of this addiction.

  11. Presynaptic α4β2 nicotinic acetylcholine receptors increase glutamate release and serotonin neuron excitability in the dorsal raphe nucleus.

    Science.gov (United States)

    Garduño, Julieta; Galindo-Charles, Luis; Jiménez-Rodríguez, Javier; Galarraga, Elvira; Tapia, Dagoberto; Mihailescu, Stefan; Hernandez-Lopez, Salvador

    2012-10-24

    Several behavioral effects of nicotine are mediated by changes in serotonin (5-HT) release in brain areas that receive serotonergic afferents from the dorsal raphe nucleus (DRN). In vitro experiments have demonstrated that nicotine increases the firing activity in the majority of DRN 5-HT neurons and that DRN contains nicotinic acetylcholine receptors (nAChRs) located at both somata and presynaptic elements. One of the most common presynaptic effects of nicotine is to increase glutamate release. Although DRN receives profuse glutamatergic afferents, the effect of nicotine on glutamate release in the DRN has not been studied in detail. Using whole-cell recording techniques, we investigated the effects of nicotine on the glutamatergic input to 5-HT DRN neurons in rat midbrain slices. Low nicotine concentrations, in the presence of bicuculline and tetrodotoxin (TTX), increased the frequency but did not change the amplitude of glutamate-induced EPSCs, recorded from identified 5-HT neurons. Nicotine-induced increase of glutamatergic EPSC frequency persisted 10-20 min after drug withdrawal. This nicotinic effect was mimicked by exogenous administration of acetylcholine (ACh) or inhibition of ACh metabolism. In addition, the nicotine-induced increase in EPSC frequency was abolished by blockade of α4β2 nAChRs, voltage-gated calcium channels, or intracellular calcium signaling but not by α7 nAChR antagonists. These data suggest that both nicotine and endogenous ACh can increase glutamate release through activation of presynaptic α4β2 but not α7 nAChRs in the DRN. The effect involves long-term changes in synaptic function, and it is dependent on voltage-gated calcium channels and presynaptic calcium stores.

  12. Central amygdala nicotinic and 5-HT1A receptors mediate the reversal effect of nicotine and MDMA on morphine-induced amnesia.

    Science.gov (United States)

    Tirgar, F; Rezayof, A; Zarrindast, M-R

    2014-09-26

    The present study was designed to investigate possible involvement of the central amygdala (CeA) nicotinic acetylcholine (nACh) and 5-hydroxytryptamine 1A (5-HT1A) receptors in the reversal effect of nicotine and 3,4-methylenedioxy-N-methylamphetamine (MDMA or ecstasy) on morphine-induced amnesia. Two guide cannulas were stereotaxically implanted in the CeA regions and a step-through passive avoidance task was used for the assessment of memory retrieval in adult male Wistar rats. Our results indicated that post-training s.c. administration of morphine (3-7-mg/kg) impaired memory retrieval. Pre-test administration of nicotine (0.3- and 0.5-mg/kg, s.c.) reversed morphine-induced amnesia. In addition, pre-test intra-CeA injection of MDMA (1-2-μg/rat) with an ineffective dose of nicotine (0.1-mg/kg, s.c.) improved memory retrieval, suggesting the interactive effect of the drugs on memory formation. It should be noted that that pre-test intra-CeA injection of 2-μg/rat of MDMA by itself produced amnesia. Interestingly, pre-test intra-CeA injection of mecamylamine, a nACh receptor antagonist (1-2-μg/rat) or (S)-WAY 100135 (0.25-1-μg/rat), a selective 5-HT1A receptor antagonist inhibited the improvement of morphine-induced amnesia which was produced by pre-test co-injection of nicotine and MDMA. Pre-test intra-CeA injection of the same doses of MDMA, mecamylamine or (S)-WAY 100135 by itself had no effect on morphine-induced amnesia. Moreover, pre-test injection of the same doses of mecamylamine or (S)-WAY 100135 into the CeA alone could not change memory retrieval. Taken together, it can be concluded that there is a functional interaction between morphine, nicotine and MDMA via the CeA nicotinic and serotonergic receptor mechanisms in passive avoidance memory retrieval. Moreover, cross state-dependent memory retrieval may have been induced between the drugs and this probably depends on the rewarding effects of the drugs. Copyright © 2014 IBRO. Published by Elsevier

  13. Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells

    Directory of Open Access Journals (Sweden)

    L.F.S. Sampaio

    2005-04-01

    Full Text Available The influence of melatonin on the developmental pattern of functional nicotinic acetylcholine receptors was investigated in embryonic 8-day-old chick retinal cells in culture. The functional response to acetylcholine was measured in cultured retina cells by microphysiometry. The maximal functional response to acetylcholine increased 2.7 times between the 4th and 5th day in vitro (DIV4, DIV5, while the Bmax value for [125I]-alpha-bungarotoxin was reduced. Despite the presence of alpha8-like immunoreactivity at DIV4, functional responses mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors were observed only at DIV5. Mecamylamine (100 µM was essentially without effect at DIV4 and DIV5, while dihydro-ß-erythroidine (10-100 µM blocked the response to acetylcholine (3.0 nM-2.0 µM only at DIV4, with no effect at DIV5. Inhibition of melatonin receptors with the antagonist luzindole, or melatonin synthesis by stimulation of D4 dopamine receptors blocked the appearance of the alpha-bungarotoxin-sensitive response at DIV5. Therefore, alpha-bungarotoxin-sensitive receptors were expressed in retinal cells as early as at DIV4, but they reacted to acetylcholine only after DIV5. The development of an alpha-bungarotoxin-sensitive response is dependent on the production of melatonin by the retinal culture. Melatonin, which is produced in a tonic manner by this culture, and is a key hormone in the temporal organization of vertebrates, also potentiates responses mediated by alpha-bungarotoxin-sensitive receptors in rat vas deferens and cerebellum. This common pattern of action on different cell models that express alpha-bungarotoxin-sensitive receptors probably reflects a more general mechanism of regulation of these receptors.

  14. Acetylcholine receptors in the retinas of the α7 nicotinic acetylcholine receptor knockout mouse.

    Science.gov (United States)

    Smith, Marci L; Souza, Fred G Oliveira; Bruce, Kady S; Strang, Christianne E; Morley, Barbara J; Keyser, Kent T

    2014-01-01

    The α7 nicotinic acetylcholine receptor (nAChR) is widely expressed in the nervous system, including in the inner retinal neurons in all species studied to date. Although reductions in the expression of α7 nAChRs are thought to contribute to the memory and visual deficits reported in Alzheimer's disease (AD) and schizophrenia , the α7 nAChR knockout (KO) mouse is viable and has only slight visual dysfunction. The absence of a major phenotypic abnormality may be attributable to developmental mechanisms that serve to compensate for α7 nAChR loss. We hypothesized that the upregulation of genes encoding other nAChR subunits or muscarinic acetylcholine receptor (mAChR) subtypes during development partially accounts for the absence of major deficiencies in the α7 nAChR KO mouse. The purpose of this study was to determine whether the deletion of the α7 nAChR subunit in a mouse model resulted in changes in the regulation of other cholinergic receptors or other ion channels in an α7 nAChR KO mouse when compared to a wild-type (WT) mouse. To examine gene expression changes, we employed a quantitative real-time polymerase chain reaction (qPCR) using whole retina RNA extracts as well as RNA extracted from selected regions of the retina. These extracts were collected using laser capture microdissection (LCM). The presence of acetylcholine receptor (AChR) subunit and subtype proteins was determined via western blotting. To determine any differences in the number and distribution of choline acetyltransferase (ChAT) amacrine cells, we employed wholemount and vertical immunohistochemistry (IHC) and cell counting. Additionally, in both WT and α7 nAChR KO mouse retinas, the distribution of the nAChR subunit and mAChR subtype proteins were determined via IHC for those KO mice that experienced mRNA changes. In the whole retina, there was a statistically significant upregulation of α2, α9, α10, β4, nAChR subunit, and m1 and m4 mAChR subtype transcripts in the α7 nAChR KO

  15. Crystal structure of an ACh-binding protein reveals the ligand-binding domain of nicotinic receptors

    NARCIS (Netherlands)

    Brejc, K.; Dijk, van W.J.; Klaassen, R.V.; Schuurmans, M.; Oost, van der J.; Smit, A.B.; Sixma, T.K.

    2001-01-01

    Pentameric ligand gated ion-channels, or Cys-loop receptors, mediate rapid chemical transmission of signals. This superfamily of allosteric transmembrane proteins includes the nicotinic acetylcholine (nAChR), serotonin 5-HT3, -aminobutyric-acid (GABAA and GABAC) and glycine receptors. Biochemical

  16. Nicotine-induced molecular alterations are modulated by GABAB receptor activity.

    Science.gov (United States)

    Varani, Andres P; Pedrón, Valeria T; Aon, Amira J; Höcht, Christian; Acosta, Gabriela B; Bettler, Bernhard; Balerio, Graciela N

    2017-04-17

    It has been demonstrated that GABAB receptors modulate nicotine (NIC) reward effect; nevertheless, the mechanism implicated is not well known. In this regard, we evaluated the involvement of GABAB receptors on the behavioral, neurochemical, biochemical and molecular alterations associated with the rewarding effects induced by NIC in mice, from a pharmacological and genetic approach. NIC-induced rewarding properties (0.5 mg/kg, subcutaneously, sc) were evaluated by conditioned place preference (CPP) paradigm. CPP has three phases: preconditioning, conditioning and postconditioning. GABAB receptor antagonist 2-hydroxysaclofen (0.25, 0.5 and 1 mg/kg; intraperitoneally, ip) or the GABAB receptor agonist baclofen (3 mg/kg; ip) was injected before NIC during the conditioning phase. GABAB1 knockout (GABAB1 KO) mice received NIC during the conditioning phase. Vehicle and wild-type controls were employed. Neurochemical (dopamine, serotonin and their metabolites), biochemical (nicotinic receptor α4β2, α4β2nAChRs) and molecular (c-Fos) alterations induced by NIC were analyzed after the postconditioning phase by high-performance liquid chromatography (HPLC), receptor-ligand binding assays and immunohistochemistry, respectively, in nucleus accumbens (Acb), prefrontal cortex (PFC) and ventral tegmental area (VTA). NIC induced rewarding effects in the CPP paradigm and increased dopamine levels in Acb and PFC, α4β2nAChRs density in VTA and c-Fos expression in Acb shell (AcbSh), VTA and PFC. We showed that behavioral, neurochemical, biochemical and molecular alterations induced by NIC were prevented by baclofen. However, in 2-hydroxysaclofen pretreated and GABAB1 KO mice, these alterations were potentiated, suggesting that GABAB receptor activity is necessary to control alterations induced by NIC-induced rewarding effects. Therefore, the present findings provided important contributions to the mechanisms implicated in NIC-induced rewarding effects. © 2017 Society for the

  17. [Blockade of the alpha3alpha4 N-cholinoreceptors and GluR1 AMPA receptors eliminates clonic-tonic nicotinic and kainate seizures].

    Science.gov (United States)

    Serdiuk, S E; Gmiro, V E

    2008-01-01

    Monoammonium N-alkyl derivative of decylamine (IEM-1678), which blocks alpha3beta4 N-cholinoreceptors (but does not block GluR1 AMPA receptors), in doses of 1.0 - 3.0 mg/kg produces a 4-fold decrease in the frequency and lethality of nicotinic clonic-tonic seizures. However, even in the maximum dose of 3 mg/kg, IEM-1678 only slightly decreases kainate clonic-tonic seizures. Bis-ammonium compound IEM-1460 (containing adamantyl radical), which blocks both GluR1 AMPA receptors and alpha3beta4 N-cholinoreceptors, in a range of doses 0.1 - 3 mg/kg produces a 5- to 8-fold decrease in the frequency and virtually completely eliminates lethality of both clonic-tonic nicotinic and kainate seizures. Hence, the complete elimination of generalized kainate and nicotinic seizures requires combined blockade GluR1 AMPA and alpha3beta4 N-cholinoreceptors.

  18. Nicotinic receptor-associated modulation of stimulatory and inhibitory neurotransmitters in NNK-induced adenocarcinoma of the lungs and pancreas

    Science.gov (United States)

    Al-Wadei, Hussein A. N.; Schuller, Hildegard M.

    2012-01-01

    Small airway-derived pulmonary adenocarcinoma (PAC) and pancreatic ductal adenocarcinoma (PDAC) are among the most common human cancers and smoking is a risk factor for both. Emerging research has identified cAMP signaling stimulated by the stress neurotransmitters adrenaline and noradrenaline as important stimulators of several adenocarcinomas, including PAC and PDAC. The nicotine-derived nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent mutagen and the most powerful tobacco carcinogen. NNK is also an agonist for nicotinic acetylcholine receptors (nAChRs). Using hamster models of NNK-induced PAC and PDAC, we have tested the hypothesis that in analogy to chronic effects of nicotine in the brain, NNK may modulate the α7- and α4β2nAChRs, causing an increase in stress neurotransmitters and decrease in the inhibitory neurotransmitter γ-aminobutyric acid (GABA). In support of our hypothesis, immunoassays showed a significant increase in serum adrenaline/noradrenaline and increased intracellular cAMP in the cellular fraction of blood of NNK treated hamsters. Western blots were done with cells harvested by laser capture microcopy from control small airway epithelia, alveolar epithelia, pancreatic islet and pancreatic duct epithelia and from NNK-induced PACs and PDACs. The GABA synthesizing enzyme glutamate decarboxylase 65 (GAD65) and GABA were suppressed in NNK-induced PACs and PDACs whereas protein expression of the α7nAChR, α4nAChR as well as p-CREB and p-ERK1/2 were upregulated. These findings suggest, for the first time, that NNK-induced alterations in regulatory nAChRs may contribute to the development of smoking-associated PAC and PDAC by disturbing the balance between cancer stimulating and inhibiting neurotransmitters. PMID:19274673

  19. The role of alpha-7 nicotinic receptors in food intake behaviors

    Directory of Open Access Journals (Sweden)

    Kristina L. McFadden

    2014-06-01

    Full Text Available Nicotine alters appetite and energy expenditure, leading to changes in body weight. While the exact mechanisms underlying these effects are not fully established, both central and peripheral involvement of the alpha-7 nicotinic acetylcholine receptor (α7nAChR has been suggested. Centrally, the α7nAChR modulates activity of hypothalamic neurons involved in food intake regulation, including proopiomelanocortin (POMC and neuropeptide Y (NPY. α7nAChRs also modulate glutamatergic and dopaminergic systems controlling reward processes that affect food intake. Additionally, α7nAChRs are important peripheral mediators of chronic inflammation, a key contributor to health problems in obesity. This review focuses on nicotinic cholinergic effects on eating behaviors, specifically those involving the α7nAChR, with the hypothesis that α7nAChR agonism leads to appetite suppression. Recent studies are highlighted that identify links between α7nAChR expression and obesity, insulin resistance, and diabetes and describe early findings showing an α7nAChR agonist to be associated with reduced weight gain in a mouse model of diabetes. Given these effects, the α7nAChR may be a useful therapeutic target for strategies to treat and manage obesity.

  20. Mice Lacking the Alpha9 Subunit of the Nicotinic Acetylcholine Receptor Exhibit Deficits in Frequency Difference Limens and Sound Localization

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    Amanda Clause

    2017-06-01

    Full Text Available Sound processing in the cochlea is modulated by cholinergic efferent axons arising from medial olivocochlear neurons in the brainstem. These axons contact outer hair cells in the mature cochlea and inner hair cells during development and activate nicotinic acetylcholine receptors composed of α9 and α10 subunits. The α9 subunit is necessary for mediating the effects of acetylcholine on hair cells as genetic deletion of the α9 subunit results in functional cholinergic de-efferentation of the cochlea. Cholinergic modulation of spontaneous cochlear activity before hearing onset is important for the maturation of central auditory circuits. In α9KO mice, the developmental refinement of inhibitory afferents to the lateral superior olive is disturbed, resulting in decreased tonotopic organization of this sound localization nucleus. In this study, we used behavioral tests to investigate whether the circuit anomalies in α9KO mice correlate with sound localization or sound frequency processing. Using a conditioned lick suppression task to measure sound localization, we found that three out of four α9KO mice showed impaired minimum audible angles. Using a prepulse inhibition of the acoustic startle response paradigm, we found that the ability of α9KO mice to detect sound frequency changes was impaired, whereas their ability to detect sound intensity changes was not. These results demonstrate that cholinergic, nicotinic α9 subunit mediated transmission in the developing cochlear plays an important role in the maturation of hearing.

  1. [[sup 3]H]imidacloprid: synthesis of a candidate radioligand for the nicotinic acetylcholine receptor

    Energy Technology Data Exchange (ETDEWEB)

    Latli, B.; Casida, J.E. (California Univ., Berkeley, CA (United States). Dept. of Entomological Sciences)

    1992-08-01

    Imidacloprid is an exceptionally potent insecticide known from physiological studies to act at the nicotinic acetylcholine receptor. To prepare [[sup 3]H]imidacloprid as a candidate radioligand, 6-chloronicotinoyl chloride was reduced with NaB[sup 2]H[sub 4] (in model studies) or NaB[sup 3]H[sub 4] in absolute ethanol to 2-chloro-5-pyridinylmethanol which was transformed to 2-chloro-5-chloromethylpyridine on refluxing with thionyl chloride. Coupling with 4,5-dihydro-N-nitro-1H-imidazol-2-amine then gave [[sup 2]H[sub 2

  2. Oxime reactivators and their in vivo and in vitro effects on nicotinic receptors

    Czech Academy of Sciences Publication Activity Database

    Soukup, O.; Krůšek, Jan; Kaniaková, Martina; Kumar, U. K.; Oz, M.; Jun, D.; Fusek, J.; Kuča, K.; Tobin, G.

    2011-01-01

    Roč. 60, č. 4 (2011), s. 679-686 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA202/09/0806; GA MŠk(CZ) LC554 Grant - others:GA ČR(CZ) GAP303/11/1907 Institutional research plan: CEZ:AV0Z50110509 Keywords : organophosphates * patch-clamp * nicotinic receptors * reactivator * isometric muscle contraction * TE671 cells Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 1.555, year: 2011

  3. Thujone inhibits the function of α7-nicotinic acetylcholine receptors and impairs nicotine-induced memory enhancement in one-trial passive avoidance paradigm.

    Science.gov (United States)

    Sultan, Ahmed; Yang, Keun-Hang Susan; Isaev, Dmitro; Nebrisi, Eslam El; Syed, Nurulain; Khan, Nadia; Howarth, Christopher F; Sadek, Bassem; Oz, Murat

    2017-06-01

    Effects of thujone, a major ingredient of absinthe, wormwood oil and some herbal medicines, were tested on the function of α7 subunit of the human nicotinic acetylcholine (α7 nACh) receptor expressed in Xenopus oocytes using the two-electrode voltage-clamp technique. Thujone reversibly inhibited ACh (100μM)-induced currents with an IC50 value of 24.7μM. The effect of thujone was not dependent on the membrane potential and did not involve Ca2+-dependent Cl- channels expressed endogenously in oocytes. Inhibition by thujone was not reversed by increasing ACh concentrations. Moreover, specific binding of [125I] α-bungarotoxin was not altered by thujone. Further experiments in SH-EP1 cells expressing human α7 nACh receptor indicated that thujone suppressed choline induced Ca2+ transients in a concentration-dependent manner. In rat hippocampal CA3-dentate gyrus synapses, nicotine-induced enhancement of long-term potentiation was also inhibited by thujone. Furthermore, the results observed in in-vivo one-trial passive avoidance paradigm show that thujone (1.25mg/kg, i.p.) significantly impaired nicotine-induced enhancement of learning and memory in Wistar rats. Collectively, our results indicate that thujone inhibits the function of the α7-nACh receptor and impairs cellular and behavioral correlates of cholinergic modulation of learning and memory. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Neuroanatomical and neuropharmacological approaches to postictal antinociception-related prosencephalic neurons: the role of muscarinic and nicotinic cholinergic receptors

    Science.gov (United States)

    de Freitas, Renato Leonardo; Bolognesi, Luana Iacovelo; Twardowschy, André; Corrêa, Fernando Morgan Aguiar; Sibson, Nicola R; Coimbra, Norberto Cysne

    2013-01-01

    Several studies have suggested the involvement of the hippocampus in the elaboration of epilepsy. There is evidence that suggests the hippocampus plays an important role in the affective and motivational components of nociceptive perception. However, the exact nature of this involvement remains unclear. Therefore, the aim of this study was to determine the role of muscarinic and nicotinic cholinergic receptors in the dorsal hippocampus (dH) in the organization of postictal analgesia. In a neuroanatomical study, afferent connections were found from the somatosensory cortex, the medial septal area, the lateral septal area, the diagonal band of Broca, and the dentate gyrus to the dH; all these areas have been suggested to modulate convulsive activity. Outputs to the dH were also identified from the linear raphe nucleus, the median raphe nucleus (MdRN), the dorsal raphe nucleus, and the locus coeruleus. All these structures comprise the endogenous pain modulatory system and may be involved either in postictal pronociception or antinociception that is commonly reported by epileptic patients. dH-pretreatment with cobalt chloride (1.0 mmol/L CoCl2/0.2 μL) to transiently inhibit local synapses decreased postictal analgesia 10 min after the end of seizures. Pretreatment of the dH with either atropine or mecamylamine (1.0 μg/0.2 μL) attenuated the postictal antinociception 30 min after seizures, while the higher dose (5.0 μg/0.2 μL) decreased postictal analgesia immediately after the end of seizures. These findings suggest that the dH exerts a critical role in the organization of postictal analgesia and that muscarinic and nicotinic cholinergic receptor-mediated mechanisms in the dH are involved in the elaboration of antinociceptive processes induced by generalized tonic-clonic seizures. PMID:23785660

  5. Alteration in contractile G-protein coupled receptor expression by moist snuff and nicotine in rat cerebral arteries

    DEFF Research Database (Denmark)

    Sandhu, Hardip; Xu, Cang-Bao; Edvinsson, Lars

    2011-01-01

    of vasocontractile G-protein coupled receptors (GPCR), such as endothelin ET(B), serotonin 5-HT(1B), and thromboxane A(2) TP receptors, in rat cerebral arteries. Studies show that these vasocontractile GPCR show alterations by lipid-soluble cigarette smoke particles via activation of mitogen-activated protein...... kinases (MAPK). However, the effects of moist tobacco on the expression of GPCR are less studied. Rat middle cerebral arteries were isolated and organ cultured in serum-free medium for 24h in the presence of water-soluble snus (WSS), DMSO-soluble snus (DSS), or nicotine. The dose of snus and nicotine...... was kept at plasma level of snus users (25ng nicotine/ml). A high dose (250ng nicotine/ml) was also included due to the previous results showing alteration in the GPCR expression by nicotine at this concentration. Contractile responses to the ET(B) receptor agonist sarafotoxin 6c, 5-HT(1B) receptor agonist...

  6. Nicotine-Mediated Regulation of Nicotinic Acetylcholine Receptors in Non-Small Cell Lung Adenocarcinoma by E2F1 and STAT1 Transcription Factors.

    Directory of Open Access Journals (Sweden)

    Courtney Schaal

    Full Text Available Cigarette smoking is the major risk factor for non-small cell lung cancer (NSCLC, which accounts for 80% of all lung cancers. Nicotine, the addictive component of tobacco smoke, can induce proliferation, migration, invasion, epithelial-mesenchymal transition (EMT, angiogenesis, and survival in NSCLC cell lines, as well as growth and metastasis of NSCLC in mice. This nicotine-mediated tumor progression is facilitated through activation of nicotinic acetylcholine receptors (nAChRs, specifically the α7 subunit; however, how the α7 nAChR gene is regulated in lung adenocarcinoma is not fully clear. Here we demonstrate that the α7 nAChR gene promoter is differentially regulated by E2F and STAT transcription factors through a competitive interplay; E2F1 induces the promoter, while STAT transcription factors repress it by binding to an overlapping site at a region -294 through -463bp upstream of the transcription start site. Treatment of cells with nicotine induced the mRNA and protein levels of α7 nAChR; this could be abrogated by treatment with inhibitors targeting Src, PI3K, MEK, α7 nAChR, CDK4/6 or a disruptor of the Rb-Raf-1 interaction. Further, nicotine-mediated induction of α7 nAChR was reduced when E2F1 was depleted and in contrast elevated when STAT1 was depleted by siRNAs. Interestingly, extracts from e-cigarettes, which have recently emerged as healthier alternatives to traditional cigarette smoking, can also induce α7 nAChR expression in a manner similar to nicotine. These results suggest an autoregulatory feed-forward loop that induces the levels of α7 nAChR upon exposure to nicotine, which enhances the strength of the signal. It can be imagined that such an induction of α7 nAChR contributes to the tumor-promoting functions of nicotine.

  7. Nicotine-Mediated Regulation of Nicotinic Acetylcholine Receptors in Non-Small Cell Lung Adenocarcinoma by E2F1 and STAT1 Transcription Factors.

    Science.gov (United States)

    Schaal, Courtney; Chellappan, Srikumar

    2016-01-01

    Cigarette smoking is the major risk factor for non-small cell lung cancer (NSCLC), which accounts for 80% of all lung cancers. Nicotine, the addictive component of tobacco smoke, can induce proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, and survival in NSCLC cell lines, as well as growth and metastasis of NSCLC in mice. This nicotine-mediated tumor progression is facilitated through activation of nicotinic acetylcholine receptors (nAChRs), specifically the α7 subunit; however, how the α7 nAChR gene is regulated in lung adenocarcinoma is not fully clear. Here we demonstrate that the α7 nAChR gene promoter is differentially regulated by E2F and STAT transcription factors through a competitive interplay; E2F1 induces the promoter, while STAT transcription factors repress it by binding to an overlapping site at a region -294 through -463bp upstream of the transcription start site. Treatment of cells with nicotine induced the mRNA and protein levels of α7 nAChR; this could be abrogated by treatment with inhibitors targeting Src, PI3K, MEK, α7 nAChR, CDK4/6 or a disruptor of the Rb-Raf-1 interaction. Further, nicotine-mediated induction of α7 nAChR was reduced when E2F1 was depleted and in contrast elevated when STAT1 was depleted by siRNAs. Interestingly, extracts from e-cigarettes, which have recently emerged as healthier alternatives to traditional cigarette smoking, can also induce α7 nAChR expression in a manner similar to nicotine. These results suggest an autoregulatory feed-forward loop that induces the levels of α7 nAChR upon exposure to nicotine, which enhances the strength of the signal. It can be imagined that such an induction of α7 nAChR contributes to the tumor-promoting functions of nicotine.

  8. [Effects of piracetam and meclofenoxate on the brain NMDA and nicotinic receptors in mice with different exploratory efficacy in the cross maze test].

    Science.gov (United States)

    Kovalev, G I; Firstova, Iu Iu; Salimov, R M

    2008-01-01

    A population of outbred mice of the ICR strain was divided into two subpopulations according to their high (EH mice) or low (EL mice) exploratory efficacy in the closed cross maze test. In addition, the EH and EL mice differed in the number of binding sites of (i) [G-3H]-MK-801 with NMDA receptors from hippocampus and (ii) [G-3H]-nicotine with nicotine cholinoreceptors (nACh) from neocortex. A subchronic administration of the cognition enhancer piracetam (200 mg/kg, once per day for 5 days) increased by 70% the number of binding sites of NMDA receptors in the EL mice. At the same time, this treatment decreased the density of neocortical nACh receptors in both EL and EH mice (by 55% and 40%, respectively). A subchronic administration of the cognition enhancer and anti-oxidant meclofenoxate (100 mg/kg, once per day for 5 days) also decreased the density of neocortical nACh receptors in both EL and EH mice (by 48% and 20%, respectively). However, meclofenoxate also increased by 41% the number of binding sites of NMDA receptors in the EH mice.

  9. Alteration in contractile G-protein coupled receptor expression by moist snuff and nicotine in rat cerebral arteries

    DEFF Research Database (Denmark)

    Sandhu, Hardip; Xu, Cang-Bao; Edvinsson, Lars

    2011-01-01

    The cardiovascular risk for users of use of Swedish snus/American snuff (moist tobacco) has been debated for a long time. The present study was designed to examine the effects of water- or lipid-soluble (DMSO-soluble) snus and nicotine, the most important substance in tobacco, on the expression...... kinases (MAPK). However, the effects of moist tobacco on the expression of GPCR are less studied. Rat middle cerebral arteries were isolated and organ cultured in serum-free medium for 24h in the presence of water-soluble snus (WSS), DMSO-soluble snus (DSS), or nicotine. The dose of snus and nicotine...... by an increased mRNA expression for the receptor. Thus, snus and nicotine alter the GPCR expression in the cerebral arteries, which may be involved in cerebral vascular disease....

  10. Existence of Nicotinic Receptors in A Subset of Type I Vestibular Hair Cells of Guinea Pigs.

    Science.gov (United States)

    Guo, Chang-Kai

    2017-12-30

    In mammals, vestibular hair cells (VHCs) are classified as type I and II according to morphological criteria. Acetylcholine (ACh) is identified as the primary efferent neurotransmitter. To date, cholinergic activities have been reported in mammalian type II VHCs, but similar activities in type I VHCs have not been pursued presumably because the body of type I VHCs were suggested to be totally surrounded by afferent nerve calyces. A few reports showed that part of type I VHCs were incompletely surrounded by calyces and received contact from the efferent nerve endings in the mammals studied. The possibility of the expression of cholinergic receptors, their subunit composition, and their function in mammals' type I VHCs are still unclear. In this study, nicotinic responses were investigated by the whole-cell patch clamp technique in isolated type I VHCs of guinea pigs. Of the cells, 7.3% were sensitive to cholinergic agonists and showed an excitatory current at -40mV which was not sensitive to nifedipine, iberiotoxin (IBTX), and apamin. The main carriers of this current were Na+ and K+. The rank order of activation potency was nicotine > 1,1-dimethyl-4-phenyl-piperazinium (DMPP) > ACh. These nicotinic ACh receptors (nAChRs) were not blocked by strychnine and α-bungarotoxin (α-BTX), but sensitive to d-tubocurarine (dTC) and mecamylamine (Mec). The findings provide physiological evidence that some subtypes of nAChRs may be located in a subset of type I VHCs, which were different from α9α10 nAChRs. Copyright © 2017. Published by Elsevier B.V.

  11. Expression of nicotinic acetylcholine receptors on human B-lymphoma cells

    Directory of Open Access Journals (Sweden)

    Skok M. V.

    2009-12-01

    Full Text Available Aim. To find a correlation between the level of nicotinic acetylcholine receptor (nAChR expression and B lymphocyte differentiation or activation state. Methods. Expression of nAChRs in the REH, Ramos and Daudi cell lines was studied by flow cytometry using nAChR subunit-specific antibodies; cell proliferation was studied by MTT test. Results. It is shown that the level of 42/4 and 7 nAChRs expression increased along with B lymphocyte differentiation (Ramos > REH and activation (Daudi > > Ramos and depended on the antigen-specific receptor expression. The nAChR stimulation/blockade did not influence the intensity of cell proliferation.

  12. Gene expression of pro-opiomelanocortin and melanocortin receptors is regulated in the hypothalamus and mesocorticolimbic system following nicotine administration.

    Science.gov (United States)

    Tapinc, Damla E; Ilgin, Rabia; Kaya, Egemen; Gozen, Oguz; Ugur, Muzeyyen; Koylu, Ersin O; Kanit, Lutfiye; Keser, Aysegul; Balkan, Burcu

    2017-01-10

    Pro-opiomelanocortin (POMC)-derived peptides and their receptors have been shown to play important roles in natural and drug-induced reward and reinforcement. Reward process may involve the regulation of POMC gene expression and the gene expression of POMC-derived peptide receptors. The present study investigated the alterations observed in the transcript levels of POMC, melanocortin 3 (MC3R), melanocortin 4 (MC4R) and mu-opioid receptors (MOR) in the hypothalamus and mesocorticolimbic system during nicotine exposure. Rats were injected subcutaneously for 5days with one of the three doses (0.2, 0.4 or 0.6mg/kg/day, free base) of nicotine and were decapitated one hour after a challenge dose on the sixth day. mRNA levels of POMC in the hypothalamus, MC3R in the ventral tegmental area (VTA), MC4R and MOR in the medial prefrontal cortex (mPFC), nucleus accumbens, dorsal striatum, amygdala, lateral hypothalamic area and VTA were measured by quantitative real-time PCR. Our results showed that treatment with 0.6mg/kg/day nicotine upregulated POMC mRNA in the hypothalamus and MC4R mRNA in the mPFC. Additionally, all three nicotine doses increased MC3R mRNA expression in the VTA. On the other hand, none of the nicotine doses altered MOR mRNA levels in the mesocorticolimbic system and associated limbic structures. These results suggest that nicotine may enhance melanocortin signaling in the mesocorticolimbic system and this alteration may be an important mechanism mediating nicotine reward. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Nicotine-induced norepinephrine release in hypothalamic paraventricular nucleus and amygdala is mediated by N-methyl-D-aspartate receptors and nitric oxide in the nucleus tractus solitarius.

    Science.gov (United States)

    Zhao, Rongjie; Chen, Hao; Sharp, Burt M

    2007-02-01

    The noradrenergic projections from brainstem nucleus tractus solitarius (NTS) to hypothalamic paraventricular nucleus (PVN) and amygdala (AMYG) are involved in nicotine-related stress responses and drug craving. Previous studies demonstrated that i.v. nicotine-induced norepinephrine (NE) release in the PVN and AMYG depends on nicotinic cholinergic receptors in the brainstem. However, the direct site and mechanism of nicotine's action in brainstem are unknown. The present study determined the roles of NTS ionotropic glutamate receptors and nitric oxide (NO) in the effects of both local and systemic nicotine on NE release in PVN and AMYG. In male rats, an intra-NTS microinjection of nicotine (1.2 microg free base) or i.v. nicotine infusion (0.065 or 0.09 mg/kg) significantly increased NE levels in PVN and AMYG microdialysates. Prior microinjection of the N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonopentanoic acid (0.75 or 1.5 microg), but not an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist, dose dependently nearly abolished both PVN and AMYG NE responses to nicotine administered into NTS or systemically. NO involvement was assessed with intra-NTS microinjections of the nonselective nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester hydrochloride (10-30 nmol), or the NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (0.1-0.2 nmol); both agents dose dependently inhibited i.v. nicotine-induced NE release. These results indicate that nicotine-induced NE release in PVN and AMYG is mediated entirely through the local effects of nicotine on NTS glutamate afferents and NMDA receptors that, in part, stimulate NO production, resulting in activation of noradrenergic neurons. Therefore, nicotine acts indirectly on noradrenergic NTS neurons to elicit NE release in forebrain structures.

  14. NICOTINE-RECEPTOR BLOCKADE AND THE EFFECTS OF ANATOXIN-A ON THE MOTOR ACTIVITY OF RATS: COMPARISON WITH NICOTINE.

    Science.gov (United States)

    Anatoxin-a is produced by several species of freshwater cyanobacteria and has caused several poisoning episodes in terrestrial and aquatic wildlife, livestock and domestic animals. Anatoxin-a is also a potent nicotinic agonist in the nervous system and at the neuromuscular juncti...

  15. Pharmacogenetic study of seven polymorphisms in three nicotinic acetylcholine receptor subunits in smoking-cessation therapies.

    Science.gov (United States)

    Pintarelli, Giulia; Galvan, Antonella; Pozzi, Paolo; Noci, Sara; Pasetti, Giovanna; Sala, Francesca; Pastorino, Ugo; Boffi, Roberto; Colombo, Francesca

    2017-12-01

    Smoking-cessation therapy reduces the risk of smoking-related diseases, but is successful only in a fraction of smokers. There is growing evidence that genetic variations in nicotinic acetylcholine receptor (nAChR) subunits influence the risk of nicotine dependence and the ability to quit smoking. To investigate the role of polymorphisms in nAChR genes on smoking quantity and the outcome of smoking-cessation therapies, we carried out an association study on 337 smokers who underwent pharmacotherapy with varenicline, bupropion, nicotine replacement therapy (NRT) alone, or NRT plus bupropion. Smoking habit and abstention were assessed from the number of cigarettes smoked per day (CPD) and the exhaled CO (eCO), at baseline and up to 12 months. We genotyped seven polymorphisms in genes encoding the nAChR subunits CHRNA4, CHRNA5, and CHRNB2. At baseline, both CPD and eCO were associated with polymorphisms in the CHRNA5 locus (rs503464, rs55853698, rs55781567 and rs16969968; P < 0.01). rs503464, a variant in the 5'-UTR of CHRNA5, was also associated with short-, mid- and long-term responses to therapy (P = 0.011, P = 0.0043, P = 0.020, respectively), although after correction for multiple testing only the association at the mid-term assessment remained significant (FDR = 0.03). These data support the role of individual genetic makeup in the ability to quit smoking.

  16. Amelioration strategies fail to prevent tobacco smoke effects on neurodifferentiation: Nicotinic receptor blockade, antioxidants, methyl donors.

    Science.gov (United States)

    Slotkin, Theodore A; Skavicus, Samantha; Card, Jennifer; Levin, Edward D; Seidler, Frederic J

    2015-07-03

    Tobacco smoke exposure is associated with neurodevelopmental disorders. We used neuronotypic PC12 cells to evaluate the mechanisms by which tobacco smoke extract (TSE) affects neurodifferentiation. In undifferentiated cells, TSE impaired DNA synthesis and cell numbers to a much greater extent than nicotine alone; TSE also impaired cell viability to a small extent. In differentiating cells, TSE enhanced cell growth at the expense of cell numbers and promoted emergence of the dopaminergic phenotype. Nicotinic receptor blockade with mecamylamine was ineffective in preventing the adverse effects of TSE and actually enhanced the effect of TSE on the dopamine phenotype. A mixture of antioxidants (vitamin C, vitamin E, N-acetyl-l-cysteine) provided partial protection against cell loss but also promoted loss of the cholinergic phenotype in response to TSE. Notably, the antioxidants themselves altered neurodifferentiation, reducing cell numbers and promoting the cholinergic phenotype at the expense of the dopaminergic phenotype, an effect that was most prominent for N-acetyl-l-cysteine. Treatment with methyl donors (vitamin B12, folic acid, choline) had no protectant effect and actually enhanced the cell loss evoked by TSE; they did have a minor, synergistic interaction with antioxidants protecting against TSE effects on growth. Thus, components of tobacco smoke perturb neurodifferentiation through mechanisms that cannot be attributed to the individual effects of nicotine, oxidative stress or interference with one-carbon metabolism. Consequently, attempted amelioration strategies may be partially effective at best, or, as seen here, can actually aggravate injury by interfering with normal developmental signals and/or by sensitizing cells to TSE effects on neurodifferentiation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  17. Neo-nicotinoid metabolic activation and inactivation established with coupled nicotinic receptor-CYP3A4 and -aldehyde oxidase systems.

    Science.gov (United States)

    Honda, Hideo; Tomizawa, Motohiro; Casida, John E

    2006-02-20

    Two important enzymes in metabolism of the principal neo-nicotinoid insecticide imidacloprid are liver microsomal CYP3 A4 and cytosolic aldehyde oxidase (AOX). CYP3A4 oxidation at several molecular sites and AOX reduction at the nitro substituent result in either an increase (activation) or decrease (inactivation) of agonist potency at nicotinic acetylcholine receptors (nAChRs), both insect and vertebrate alpha 4beta 2. This study evaluates activation or inactivation of 11 neo-nicotinoids in a continuous two-step system coupling metabolism and receptor binding. For metabolism, the neo-nicotinoid is incubated with CYP3A4 and NADPH or AOX with the cosubstrate N-methyl-nicotinamide, terminating the reaction with ketoconazole or menadione, respectively, to inhibit further conversion. For receptor assay, either the Drosophila nAChR and [(3)H]imidacloprid or the alpha4 beta2 nicotinic receptor and [(3)H](-)-nicotine are added to determine changes in neo-nicotinoid potency. With the Drosophila nAChR assay, the N-methyl compounds N-methyl-imidacloprid and thiamethoxam are activated 4.5-29-fold by CYP3 A4 whereas nine other neo-nicotinoids are not changed in potency. With the vertebrate alpha4 beta2 nAChR, AOX enhances imidacloprid potency but CYP3 A4 does not. The AOX system coupled with the Drosophila receptor strongly inactivates clothianidin, dinotefuran, imidacloprid, desmethyl-thiamethoxam, and thiamethoxam with some inactivation of nitenpyram and nithiazine, and little or no effect on four other compounds.

  18. Activation and desensitization of peripheral muscle and neuronal nicotinic acetylcholine receptors by selected, naturally-occurring pyridine alkaloids

    Science.gov (United States)

    Teratogenic alkaloids can cause developmental defects due to inhibition of fetal movement that results from desensitization of fetal muscletype nicotinic acetylcholine receptors (nAChRs). We investigated the ability of two known teratogens, the piperidinyl-pyridine anabasine and its 1,2-dehydropiper...

  19. Role of nicotine dependence in the association between the Dopamine Receptor Gene DRD3 and major depressive disorder

    NARCIS (Netherlands)

    Korhonen, T.; Loukola, A.; Wedenoja, J.; Nyman, E.; Latvala, A.; Broms, U.; Happola, U.; Paunio, T.; Schrage, A.J.; Vink, J.M.; Mbarek, H.; Boomsma, D.I.; Penninx, B.W.J.H.; Pergadia, M.L.; Madden, P.A.F.; Kaprio, J.

    2014-01-01

    Background: The aims of this study were to analyze associations of dopamine receptor genes (DRD1-5) with Major Depressive Disorder (MDD) and nicotine dependence (ND), and to investigate whether ND moderates genetic influences on MDD. Methods: The sample was ascertained from the Finnish Twin Cohort.

  20. Role of Nicotine Dependence in the Association between the Dopamine Receptor Gene DRD3 and Major Depressive Disorder

    NARCIS (Netherlands)

    Korhonen, T.; Loukola, A.; Wedenoja, J.; Nyman, E.; Latvala, A.; Broms, U.; Häppölä, A.; Paunio, T.; Schrage, A.J.; Vink, J.M.; Mbarek, H.; Boomsma, D.I.; Penninx, B.W.J.H.; Pergadia, M.L.; Madden, P.A.F.; Kaprio, J.

    2014-01-01

    Background: The aims of this study were to analyze associations of dopamine receptor genes (DRD1-5 ) with Major Depressive Disorder (MDD) and nicotine dependence (ND), and to investigate whether ND moderates genetic influences on MDD. Methods: The sample was ascertained from the Finnish Twin Cohort.

  1. Inhibition of nicotinic acetylcholine receptors, a novel facet in the pleiotropic activities of snake venom phospholipases A2.

    Directory of Open Access Journals (Sweden)

    Catherine A Vulfius

    Full Text Available Phospholipases A2 represent the most abundant family of snake venom proteins. They manifest an array of biological activities, which is constantly expanding. We have recently shown that a protein bitanarin, isolated from the venom of the puff adder Bitis arietans and possessing high phospholipolytic activity, interacts with different types of nicotinic acetylcholine receptors and with the acetylcholine-binding protein. To check if this property is characteristic to all venom phospholipases A2, we have studied the capability of these enzymes from other snakes to block the responses of Lymnaea stagnalis neurons to acetylcholine or cytisine and to inhibit α-bungarotoxin binding to nicotinic acetylcholine receptors and acetylcholine-binding proteins. Here we present the evidence that phospholipases A2 from venoms of vipers Vipera ursinii and V. nikolskii, cobra Naja kaouthia, and krait Bungarus fasciatus from different snake families suppress the acetylcholine- or cytisine-elicited currents in L. stagnalis neurons and compete with α-bungarotoxin for binding to muscle- and neuronal α7-types of nicotinic acetylcholine receptor, as well as to acetylcholine-binding proteins. As the phospholipase A2 content in venoms is quite high, under some conditions the activity found may contribute to the deleterious venom effects. The results obtained suggest that the ability to interact with nicotinic acetylcholine receptors may be a general property of snake venom phospholipases A2, which add a new target to the numerous activities of these enzymes.

  2. Nicotinic acetylcholine receptor polymorphism, smoking behavior, and tobacco-related cancer and lung and cardiovascular diseases: a cohort study

    DEFF Research Database (Denmark)

    Kaur-Knudsen, Diljit; Bojesen, Stig E; Tybjærg-Hansen, Anne

    2011-01-01

    We examined the associations between the nicotinic acetylcholine receptor polymorphism (rs1051730) on chromosome 15q25 marking the gene cluster CHRNA3-CHRNB4-CHRNA5, smoking behavior, and tobacco-related cancer and lung and cardiovascular diseases in the general population....

  3. Hippocampal α7 nicotinic acetylcholine receptor levels in patients with schizophrenia, bipolar disorder, or major depressive disorder

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Weyn, Annelies; Mikkelsen, Jens D

    2011-01-01

    The α7 nicotinic acetylcholine receptor (nAChR) is involved in cognitive function and synaptic plasticity. Consequently, changes in α7 nAChR function have been implicated in a variety of mental disorders, especially schizophrenia. However, there is little knowledge regarding the levels of the α7 n...

  4. Pancreatic and snake venom presynaptically active phospholipases A2 inhibit nicotinic acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Catherine A Vulfius

    Full Text Available Phospholipases A2 (PLA2s are enzymes found throughout the animal kingdom. They hydrolyze phospholipids in the sn-2 position producing lysophospholipids and unsaturated fatty acids, agents that can damage membranes. PLA2s from snake venoms have numerous toxic effects, not all of which can be explained by phospholipid hydrolysis, and each enzyme has a specific effect. We have earlier demonstrated the capability of several snake venom PLA2s with different enzymatic, cytotoxic, anticoagulant and antiproliferative properties, to decrease acetylcholine-induced currents in Lymnaea stagnalis neurons, and to compete with α-bungarotoxin for binding to nicotinic acetylcholine receptors (nAChRs and acetylcholine binding protein. Since nAChRs are implicated in postsynaptic and presynaptic activities, in this work we probe those PLA2s known to have strong presynaptic effects, namely β-bungarotoxin from Bungarus multicinctus and crotoxin from Crotalus durissus terrificus. We also wished to explore whether mammalian PLA2s interact with nAChRs, and have examined non-toxic PLA2 from porcine pancreas. It was found that porcine pancreatic PLA2 and presynaptic β-bungarotoxin blocked currents mediated by nAChRs in Lymnaea neurons with IC50s of 2.5 and 4.8 μM, respectively. Crotoxin competed with radioactive α-bungarotoxin for binding to Torpedo and human α7 nAChRs and to the acetylcholine binding protein. Pancreatic PLA2 interacted similarly with these targets; moreover, it inhibited radioactive α-bungarotoxin binding to the water-soluble extracellular domain of human α9 nAChR, and blocked acetylcholine induced currents in human α9α10 nAChRs heterologously expressed in Xenopus oocytes. These and our earlier results show that all snake PLA2s, including presynaptically active crotoxin and β-bungarotoxin, as well as mammalian pancreatic PLA2, interact with nAChRs. The data obtained suggest that this interaction may be a general property of all PLA2s, which

  5. [The synergetic effects of nitric oxide and nicotinic acetylcholine receptor on learning and memory of rats].

    Science.gov (United States)

    Jing, Zhi-Hua; Wei, Xiao-Ming; Wang, Shao-Hu; Chen, Yu-Fen; Liu, Li-Xia; Qi, Wen-Xiu

    2014-06-25

    The aim of the present study is to explore the interaction of nitric oxide (NO) and nicotinic acetylcholine receptor (nAChR) on learning and memory of rats. Rats were intracerebroventricularly (i.c.v.) injected with L-arginine (L-Arg, the NO precursor) (L-Arg group) or choline chloride (CC, an agonist of α7nAChR) (CC group), and with combined injection of L-Arg and CC (L-Arg+CC group), and methyllycaconitine (MLA, α7nAChR antagonist) or N(ω)-nitro-L-arginine methylester (L-NAME, nitric oxide synthase inhibitor) i.c.v. injected first and followed by administration of L-Arg combined with CC (MLA+L-Arg+CC group or L-NAME+L-Arg+CC group), respectively, and normal saline was used as control (NS group). The learning and memory ability of rats was tested with Y-maze; the level of NO and the expressions of neuronal nitric oxide synthase (nNOS) or α7nAChR in hippocampus were measured by NO assay kit, immunohistochemistry or Western blot. The results showed that compared with L-Arg group or CC group, the rats' learning and memory behavioral ability in Y-maze was observably enhanced and the level of NO, the optical density of nNOS-like immunoreactivity (LI) or α7nAChR-LI in hippocampus were significantly increased in L-Arg+CC group; Compared with L-Arg+CC group, the ability of learning and memory and the level of NO as well as the expressions of nNOS-LI or α7nAChR-LI were obviously decreased in MLA+L-Arg+CC group or in L-NAME+L-Arg+CC group. In conclusion, i.c.v. administration of L-Arg combined with CC significantly improved the action of the L-Arg or CC on the content of NO and the nNOS or α7nAChR expressions in hippocampus along with the learning and memory behavior of rats; when nNOS or α7nAChR was interrupted in advance, the effects of L-Arg combined with CC were also suppressed. The results suggest that there are probably synergistic effects between NO and nAChR on learning and memory.

  6. Feeding of tobacco blend or nicotine induced weight loss associated with decreased adipocyte size and increased physical activity in male mice.

    Science.gov (United States)

    Liu, Mingxia; Chuang Key, Chia-Chi; Weckerle, Allison; Boudyguina, Elena; Sawyer, Janet K; Gebre, Abraham K; Spoo, Wayne; Makwana, Om; Parks, John S

    2018-03-01

    Although epidemiological data and results from rodent studies support an inverse relationship between nicotine consumption and body weight, the molecular mechanisms are poorly understood. CD-1 mice were fed a basal diet or a basal diet containing low or high dose smokeless tobacco blend or high dose nicotine tartrate for 14 weeks. High dose tobacco blend and nicotine tartrate diets vs. basal diet reduced mouse body weight (16.3% and 19.7%, respectively), epididymal (67.6% and 72.5%, respectively) and brown adipose weight (42% and 38%, respectively), epididymal adipocyte size (46.4% and 41.4%, respectively), and brown adipose tissue lipid droplet abundance, with no elevation of adipose tissue inflammation. High dose tobacco blend and nicotine diets also increased mouse physical activity and decreased respiratory exchange ratio, suggesting that high dose nicotine intake induces adipose tissue triglyceride lipolysis to provide fatty acids as an energy source. Both low and high dose tobacco blend and nicotine diet feeding vs. basal diet increased plasma insulin levels (2.9, 3.6 and 4.3-fold, respectively) and improved blood glucose disposal without affecting insulin sensitivity. Feeding of the high dose tobacco blend or nicotine feeding in mice induces body weight loss likely by increasing physical activity and stimulating adipose tissue triglyceride lipolysis. Copyright © 2018. Published by Elsevier Ltd.

  7. α-Conotoxin dendrimers have enhanced potency and selectivity for homomeric nicotinic acetylcholine receptors.

    Science.gov (United States)

    Wan, Jingjing; Huang, Johnny X; Vetter, Irina; Mobli, Mehdi; Lawson, Joshua; Tae, Han-Shen; Abraham, Nikita; Paul, Blessy; Cooper, Matthew A; Adams, David J; Lewis, Richard J; Alewood, Paul F

    2015-03-11

    Covalently attached peptide dendrimers can enhance binding affinity and functional activity. Homogenous di- and tetravalent dendrimers incorporating the α7-nicotinic receptor blocker α-conotoxin ImI (α-ImI) with polyethylene glycol spacers were designed and synthesized via a copper-catalyzed azide-alkyne cycloaddition of azide-modified α-ImI to an alkyne-modified polylysine dendron. NMR and CD structural analysis confirmed that each α-ImI moiety in the dendrimers had the same 3D structure as native α-ImI. The binding of the α-ImI dendrimers to binding protein Ac-AChBP was measured by surface plasmon resonance and revealed enhanced affinity. Quantitative electrophysiology showed that α-ImI dendrimers had ∼100-fold enhanced potency at hα7 nAChRs (IC50 = 4 nM) compared to native α-ImI (IC50 = 440 nM). In contrast, no significant potency enhancement was observed at heteromeric hα3β2 and hα9α10 nAChRs. These findings indicate that multimeric ligands can significantly enhance conotoxin potency and selectivity at homomeric nicotinic ion channels.

  8. Accumulation of human full-length tau induces degradation of nicotinic acetylcholine receptor ?4 via activating calpain-2

    OpenAIRE

    Yaling Yin; Yali Wang; Di Gao; Jinwang Ye; Xin Wang; Lin Fang; Dongqin Wu; Guilin Pi; Chengbiao Lu; Xin-Wen Zhou; Ying Yang; Jian-Zhi Wang

    2016-01-01

    Cholinergic impairments and tau accumulation are hallmark pathologies in sporadic Alzheimer?s disease (AD), however, the intrinsic link between tau accumulation and cholinergic deficits is missing. Here, we found that overexpression of human wild-type full-length tau (termed hTau) induced a significant reduction of ?4 subunit of nicotinic acetylcholine receptors (nAChRs) with an increased cleavage of the receptor producing a ~55kDa fragment in primary hippocampal neurons and in the rat brains...

  9. Reduction in mRNA and protein expression of a nicotinic acetylcholine receptor α8 subunit is associated with resistance to imidacloprid in the brown planthopper, Nilaparvata lugens.

    Science.gov (United States)

    Zhang, Yixi; Wang, Xin; Yang, Baojun; Hu, Yuanyuan; Huang, Lixin; Bass, Chris; Liu, Zewen

    2015-11-01

    Target-site resistance is commonly caused by qualitative changes in insecticide target-receptors and few studies have implicated quantitative changes in insecticide targets in resistance. Here we show that resistance to imidacloprid in a selected strain of Nilaparvata lugens is associated with a reduction in expression levels of the nicotinic acetylcholine receptor (nAChR) subunit Nlα8. Synergism bioassays of the selected strain suggested resistance was conferred, in part, by a target-site mechanism. Sequencing of N. lugens nAChR subunit genes identified no mutations associated with resistance, however, a decrease in mRNA and protein levels of Nlα8 was observed during selection. RNA interference knockdown of Nlα8 decreased the sensitivity of N. lugens to imidacloprid, demonstrating that a decrease in Nlα8 expression is sufficient to confer resistance in vivo. Radioligand binding assays revealed that the affinity of the high-affinity imidacloprid-binding site of native nAChRs was reduced by selection, and reducing the amount of Nlα8 cRNA injected into Xenopus oocytes significantly decreased imidacloprid potency on recombinant receptors. Taken together, these results provide strong evidence that a decrease in Nlα8 levels confers resistance to imidacloprid in N. lugens, and thus provides a rare example of target-site resistance associated with a quantitative rather than qualitative change. In insects, target-site mutations often cause high resistance to insecticides, such as neonicotinoids acting on nicotinic acetylcholine receptors (nAChRs). Here we found that a quantitative change in target-protein level, decrease in mRNA and protein levels of Nlα8, contributed importantly to imidacloprid resistance in Nilaparvata lugens. This finding provides a new target-site mechanism of insecticide resistance. © 2015 International Society for Neurochemistry.

  10. Accumulation of human full-length tau induces degradation of nicotinic acetylcholine receptor α4 via activating calpain-2.

    Science.gov (United States)

    Yin, Yaling; Wang, Yali; Gao, Di; Ye, Jinwang; Wang, Xin; Fang, Lin; Wu, Dongqin; Pi, Guilin; Lu, Chengbiao; Zhou, Xin-Wen; Yang, Ying; Wang, Jian-Zhi

    2016-06-09

    Cholinergic impairments and tau accumulation are hallmark pathologies in sporadic Alzheimer's disease (AD), however, the intrinsic link between tau accumulation and cholinergic deficits is missing. Here, we found that overexpression of human wild-type full-length tau (termed hTau) induced a significant reduction of α4 subunit of nicotinic acetylcholine receptors (nAChRs) with an increased cleavage of the receptor producing a ~55kDa fragment in primary hippocampal neurons and in the rat brains, meanwhile, the α4 nAChR currents decreased. Further studies demonstrated that calpains, including calpain-1 and calpain-2, were remarkably activated with no change of caspase-3, while simultaneous suppression of calpain-2 by selective calpain-2 inhibitor but not calpain-1 attenuated the hTau-induced degradation of α4 nAChR. Finally, we demonstrated that hTau accumulation increased the basal intracellular calcium level in primary hippocampal neurons. We conclude that the hTau accumulation inhibits nAChRs α4 by activating calpain-2. To our best knowledge, this is the first evidence showing that the intracellular accumulation of tau causes cholinergic impairments.

  11. Cognitive improvement by activation of alpha7 nicotinic acetylcholine receptors: from animal models to human pathophysiology

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hansen, Henrik H; Timmerman, Daniel B

    2010-01-01

    AChR agonists improves learning, memory, and attentional function in variety of animal models, and pro-cognitive effects of alpha(7) nAChR agonists have recently been demonstrated in patients with schizophrenia or Alzheimer's disease. The alpha(7) nAChR desensitizes rapidly in vitro, and this has been a major...... preclinical evaluation of alpha(7) nAChR activation. It is therefore important to consider the translational power of the animal models used before entering into a clinical evaluation of the pro-cognitive effects of alpha(7) nAChR activation.......Agonists and positive allosteric modulators of the alpha(7) nicotinic acetylcholine receptor (nAChR) are currently being developed for the treatment of cognitive disturbances in patients with schizophrenia or Alzheimer's disease. This review describes the neurobiological properties of the alpha n...

  12. Cognitive improvement by activation of alpha7 nicotinic acetylcholine receptors: from animal models to human pathophysiology

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hansen, Henrik H; Timmerman, Daniel B

    2010-01-01

    Agonists and positive allosteric modulators of the alpha(7) nicotinic acetylcholine receptor (nAChR) are currently being developed for the treatment of cognitive disturbances in patients with schizophrenia or Alzheimer's disease. This review describes the neurobiological properties of the alpha n......AChR and the cognitive effects of alpha(7) nAChR activation, focusing on the translational aspects in the development of these drugs. The functional properties and anatomical localization of the alpha(7) nAChR makes it well suited to modulate cognitive function. Accordingly, systemic administration of alpha(7) n......AChR agonists improves learning, memory, and attentional function in variety of animal models, and pro-cognitive effects of alpha(7) nAChR agonists have recently been demonstrated in patients with schizophrenia or Alzheimer's disease. The alpha(7) nAChR desensitizes rapidly in vitro, and this has been a major...

  13. A nicotinic receptor-mediated anti-inflammatory effect of the flavonoid rhamnetin in BV2 microglia

    Science.gov (United States)

    Lutz, Joseph A.; Kulshrestha, Manish; Rogers, Dennis T.; Littleton, John M.

    2014-01-01

    The alpha7 nicotinic acetylcholine receptor (nAChR) is a potential target in neuroinflammation. Screening a plant extract library identified Solidago nemoralis as containing methyl-quercetin derivatives that are relatively selective ligands for the alpha7 nAChR. Flavonoids are not known for this activity, so we screened a small library of pure flavonoids to confirm our findings. Some flavonoids, e.g. rhamnetin, displaced a selective alpha7 nAChR radioligand from rat brain membranes whereas similar structures e.g. sakuranetin, did not. To evaluate the contribution of this putative nAChR activity to the known anti-inflammatory properties of these flavonoids, we compared their effects on lipopolysaccharide induced release of inflammatory mediators from BV2 microglia. Both rhamnetin and sakuranetin reduced mediator release, but differed in potency (rhamnetin>sakuranetin) and the Hill slope of their concentration response curves. For rhamnetin the Hill coefficient was >3.0 whereas for sakuranetin the coefficient was 1.0, suggesting that effects of rhamnetin are mediated through more than one mechanism, whereas sakuranetin has a single mechanism. nACHR antagonists decreased the Hill coefficient for rhamnetin toward unity, which suggests that a nAChR-mediated mechanism contributes cooperatively to its overall anti-inflammatory effect. In contrast nAChR antagonists had no effect on the potency or Hill coefficient for sakuranetin, but a concentration of nicotine (1μM) that had no effect alone, significantly increased the Hill coefficient of this flavonoid. In conclusion, the anti-inflammatory effects of rhamnetin benefit cooperatively from a nAChR-mediated mechanism. This action, together with potent free radical scavenging activity, suggests that flavonoids with alpha7 nAChR activity have therapeutic potential in neuroinflammatory conditions. PMID:24972350

  14. Structural differences in the two agonist binding sites of the Torpedo nicotinic acetylcholine receptor revealed by time-resolved fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Martinez, K. L.; Corringer, P. J.; Edelstein, S. J.

    2000-01-01

    The nicotinic acetylcholine receptor (nAChR) from Torpedo marmorata carries two nonequivalent agonist binding sites at the αδ and αγ subunit interfaces. These sites have been characterized by time-resolved fluorescence with the partial nicotinic agonist dansyl-C6-choline (Dnscho). When bound...

  15. Is modulation of nicotinic acetylcholine receptors by melatonin relevant for therapy with cholinergic drugs?

    Science.gov (United States)

    Markus, Regina P; Silva, Claudia L M; Franco, Daiane Gil; Barbosa, Eduardo Mortani; Ferreira, Zulma S

    2010-06-01

    Melatonin, the darkness hormone, synchronizes several physiological functions to light/dark cycle. Besides the awake/sleep cycle that is intuitively linked to day/night, daily variations in memory acquisition and innate or acquired immune responses are some of the major activities linked to melatonin rhythm. The daily variation of these complex processes is due to changes in specific mechanisms. In the last years we focused on the influence of melatonin on the expression and function of nicotinic acetylcholine receptors (nAChRs). Melatonin, either "in vivo" or "in vitro", increases, in a selective manner, the efficiency of alpha-bungarotoxin (alpha-BTX)-sensitive nAChRs. Melatonin's effect on receptors located in rat sympathetic nerve terminals, cerebellum, skeletal muscle and chick retina, was tested. We observed that melatonin is essential for the development of alpha-BTX-sensitive nAChRs, and important for receptor maintenance in aging models. Taking into account that both melatonin and alpha-7 nAChRs (one of the subtypes sensitive to alpha-BTX) are involved in the development of Alzheimer's disease, here we discuss the possibility of a therapeutic strategy focused on both melatonin replacement and its potential association with cholinergic drugs. Copyright 2010 Elsevier Inc. All rights reserved.

  16. Molecular environment of the phencyclidine binding site in the nicotinic acetylcholine receptor membrane

    Energy Technology Data Exchange (ETDEWEB)

    Palma, A.L.; Wang, H.H. (Department of Biology, University of California, Santa Cruz (United States))

    1991-06-01

    Phencyclidine is a highly specific noncompetitive inhibitor of the nicotinic acetylcholine receptor. In a novel approach to study this site, a spin-labeled analogue of phencyclidine, 4-phenyl-4-(1-piperidinyl)-2,2,6,6-tetramethylpiperidinoxyl (PPT) was synthesized. The binding of PPT inhibits 86Rb flux (IC50 = 6.6 microM), and (3H)phencyclidine binding to both resting and desensitized acetylcholine receptor (IC50 = 17 microM and 0.22 microM, respectively). From an indirect Hill plot of the inhibition of (3H)phencyclidine binding by PPT, a Hill coefficient of approximately one was obtained in the presence of carbamylcholine and 0.8 in alpha-bungarotoxin-treated preparations. Taken together, these results indicate that PPT mimics phencyclidine in its ability to bind to the noncompetitive inhibitor site and is functionally active in blocking ion flux across the acetylcholine receptor channel. Analysis of the electron spin resonance signal of the bound PPT suggests that the environment surrounding the probe within the ion channel is hydrophobic, with a hydrophobicity parameter of 1.09. A dielectric constant for the binding site was estimated to be in the range of 2-3 units.

  17. The role of palmitoylation in functional expression of nicotinic alpha7 receptors.

    Science.gov (United States)

    Drisdel, Renaldo C; Manzana, Ehrine; Green, William N

    2004-11-17

    Neuronal alpha-bungarotoxin receptors (BgtRs) are nicotinic receptors that require as yet unidentified post-translational modifications to achieve functional expression. In this study, we examined the role of protein palmitoylation in BgtR expression. BgtR alpha7 subunits are highly palmitoylated in neurons from brain and other cells capable of BgtR expression, such as pheochromocytoma 12 (PC12) cells. In PC12 cells, alpha7 subunits are palmitoylated with a stoichiometry of approximately one palmitate per subunit, and inhibition of palmitoylation blocks BgtR expression. In cells incapable of BgtR expression, such as human embryonic kidney cells, alpha7 subunits are not significantly palmitoylated. However, in these same cells, chimeric subunits with the N-terminal half of alpha7 fused to the C-terminal half of serotonin-3A receptor (alpha7/5-HT3A) subunits form functional BgtRs that are palmitoylated to an extent similar to that of BgtRalpha7 subunits in PC12 cells. Palmitoylation of PC12 and alpha7/5-HT3A BgtRs occurred during assembly in the endoplasmic reticulum (ER). In conclusion, our data indicate a function for protein palmitoylation in which palmitoylation of assembling alpha7 subunits in the ER has a role in the formation of functional BgtRs.

  18. Interaction of alpha-conotoxin ImII and its analogs with nicotinic receptors and acetylcholine-binding proteins: additional binding sites on Torpedo receptor

    NARCIS (Netherlands)

    Kasheverov, I.E.; Zhmak, M.N.; Fish, A.; Rucktooa, P.; Khruschov, A.Y.; Osipov, A.V.; Ziganshin, R.H.; D'Hoedt, D.; Bertrand, D.; Sixma, T.K.; Smit, A.B.; Tsetlin, V.I.

    2009-01-01

    α-Conotoxins interact with nicotinic acetylcholine receptors (nAChRs) and acetylcholine-binding proteins (AChBPs) at the sites for agonists/competitive antagonists. α-Conotoxins blocking muscle-type or α7 nAChRs compete with α-bungarotoxin. However, α-conotoxin ImII, a close homolog of the α7

  19. α7 and β2 Nicotinic Acetylcholine Receptor Subunits Form Heteromeric Receptor Complexes that Are Expressed in the Human Cortex and Display Distinct Pharmacological Properties

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Zwart, Ruud; Ursu, Daniel

    2015-01-01

    The existence of α7β2 nicotinic acetylcholine receptors (nAChRs) has recently been demonstrated in both the rodent and human brain. Since α7-containing nAChRs are promising drug targets for schizophrenia and Alzheimer's disease, it is critical to determine whether α7β2 nAChRs are present...

  20. Inhibition of Toll-like receptor 2-mediated interleukin-8 production in Cystic Fibrosis airway epithelial cells via the alpha7-nicotinic acetylcholine receptor.

    LENUS (Irish Health Repository)

    Greene, Catherine M

    2010-01-01

    Cystic Fibrosis (CF) is an inherited disorder characterised by chronic inflammation of the airways. The lung manifestations of CF include colonization with Pseudomonas aeruginosa and Staphylococcus aureus leading to neutrophil-dominated airway inflammation and tissue damage. Inflammation in the CF lung is initiated by microbial components which activate the innate immune response via Toll-like receptors (TLRs), increasing airway epithelial cell production of proinflammatory mediators such as the neutrophil chemokine interleukin-8 (IL-8). Thus modulation of TLR function represents a therapeutic approach for CF. Nicotine is a naturally occurring plant alkaloid. Although it is negatively associated with cigarette smoking and cardiovascular damage, nicotine also has anti-inflammatory properties. Here we investigate the inhibitory capacity of nicotine against TLR2- and TLR4-induced IL-8 production by CFTE29o- airway epithelial cells, determine the role of alpha7-nAChR (nicotinic acetylcholine receptor) in these events, and provide data to support the potential use of safe nicotine analogues as anti-inflammatories for CF.

  1. Nicotinic acetylcholine receptor and the structural basis of neuromuscular transmission: insights from Torpedo postsynaptic membranes.

    Science.gov (United States)

    Unwin, Nigel

    2013-11-01

    The nicotinic acetylcholine (ACh) receptor, at the neuromuscular junction, is a neurotransmitter-gated ion channel that has been fine-tuned through evolution to transduce a chemical signal into an electrical signal with maximum efficiency and speed. It is composed from three similar and two identical polypeptide chains, arranged in a ring around a narrow membrane pore. Central to the design of this assembly is a hydrophobic gate in the pore, more than 50 Å away from sites in the extracellular domain where ACh binds. Although the molecular properties of the receptor have been explored intensively over the last few decades, only recently have structures emerged revealing its complex architecture and illuminating how ACh entering the binding sites opens the distant gate. Postsynaptic membranes isolated from the (muscle-derived) electric organ of the Torpedo ray have underpinned most of the structural studies: the membranes form tubular vesicles having receptors arranged on a regular surface lattice, which can be imaged directly in frozen physiological solutions. Advances in electron crystallographic techniques have also been important, enabling analysis of the closed- and open-channel forms of the receptor in unreacted tubes or tubes reacted briefly with ACh. The structural differences between these two forms show that all five subunits participate in a concerted conformational change communicating the effect of ACh binding to the gate, but that three of them (αγ, β and δ) play a dominant role. Flexing of oppositely facing pore-lining α-helices is the principal motion determining the closed/open state of the gate. These results together with the findings of biochemical, biophysical and other structural studies allow an integrated description of the receptor and of its mode of action at the synapse.

  2. Pharmacological and physiological properties of a putative ganglionic nicotinic receptor, alpha 3 beta 4, expressed in transfected eucaryotic cells.

    Science.gov (United States)

    Wong, E T; Holstad, S G; Mennerick, S J; Hong, S E; Zorumski, C F; Isenberg, K E

    1995-01-01

    Neuronal nicotinic acetylcholine receptor subunits alpha 3 (PCA48E) and beta 4S (ZPC13) were expressed in human embryonic kidney (HEK)-293 cells by calcium phosphate transfection. In the presence of atropine, acetylcholine (ACh) induced fast activating currents which exhibited desensitization and inward rectification. The EC50 for ACh was 202 +/- 32 microM with a Hill coefficient of 1.9 +/- 0.4. The rank order of nicotinic agonist potency was 1,1-dimethyl-4-phenylpiperozinium (DMPP) > cytisine = nicotine approximately equal to ACh. The maximal response elicited by DMPP was substantially less than that elicited by other agonists, suggesting that DMPP is a partial agonist. ACh (500 microM) responses were very effectively blocked by equimolar concentrations (100 microM) of the ganglionic antagonists d-tubocurarine, mecamylamine and hexamethonium. Equal concentrations of the potent muscle receptor antagonist decamethonium and the competitive antagonist dihydro-beta-erythroidine were much less effective. alpha bungaro-toxin (1 microM) had little effect on ACh-induced responses. This physiological and pharmacological profile is consistent with a ganglionic nicotinic response.

  3. Oseltamivir produces hypothermic and neuromuscular effects by inhibition of nicotinic acetylcholine receptor functions: comparison to procaine and bupropion.

    Science.gov (United States)

    Fukushima, Akihiro; Chazono, Kaori; Hashimoto, Yuichi; Iwajima, Yui; Yamamoto, Shohei; Maeda, Yasuhiro; Ohsawa, Masahiro; Ono, Hideki

    2015-09-05

    Oseltamivir, an anti-influenza virus drug, induces marked hypothermia in normal mice. We have proposed that the hypothermic effect arises from inhibition of the nicotinic acetylcholine receptor function of sympathetic ganglion neurons which innervate the brown adipose tissue (a heat generator). It has been reported that local anesthetics inhibit nicotinic acetylcholine receptor function by acting on its ionic channels, and that bupropion, a nicotinic antagonist, induces hypothermia. In this study, we compared the effects of oseltamivir, procaine and bupropion on body temperature, cardiovascular function and neuromuscular transmission. Intraperitoneal administration of oseltamivir (100mg/kg), procaine (86.6mg/kg) and bupropion (86.7mg/kg) lowered the core body temperature of normal mice. At lower doses (10-30mg/kg oseltamivir, 8.7-26mg/kg procaine and bupropion), when administered subcutaneously, the three drugs antagonized the hypothermia induced by intraperitoneal injection of nicotine (1mg/kg). In anesthetized rats, intravenous oseltamivir (30-100mg/kg), procaine (10mg/kg) and bupropion (10mg/kg) induced hypotension and bradycardia. Oseltamivir alone (100mg/kg) did not inhibit neuromuscular twitch contraction of rats, but at 3-30mg/kg it augmented the muscle-relaxing effect of d-tubocurarine. Similar effects were observed when lower doses of procaine (10-30mg/kg) and bupropion (3-10mg/kg) were administered, suggesting that systemic administration of oseltamivir inhibits muscular nicotinic acetylcholine receptors. These results support the idea that the hypothermic effect of oseltamivir is due to its effects on sympathetic ganglia which innervate the brown adipose tissue, and suggest that oseltamivir may exert non-selective ion channel blocking effects like those of ester-type local anesthetics. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Selective actions of Lynx proteins on different nicotinic acetylcholine receptors in the locust, Locusta migratoria manilensis.

    Science.gov (United States)

    Wang, Xin; Bao, Haibo; Sun, Huahua; Zhang, Yixi; Fang, Jichao; Liu, Qinghong; Liu, Zewen

    2015-08-01

    Nicotinic acetylcholine receptors (nAChRs) are major neurotransmitter receptors and targets of neonicotinoid insecticides in the insect nervous system. The full function of nAChRs is often dependent on associated proteins, such as chaperones, regulators and modulators. Here, three Lynx (Ly-6/neurotoxin) proteins, Loc-lynx1, Loc-lynx2 and Loc-lynx3, were identified in the locust, Locusta migratoria manilensis. Co-expression with Lynx resulted in a dramatic increase in agonist-evoked macroscopic currents on nAChRs Locα1/β2 and Locα2/β2 in Xenopus oocytes, but no changes in agonist sensitivity. Loc-lynx1 and Loc-lynx3 only modulated nAChRs Locα1/β2 while Loc-lynx2 modulated Locα2/β2 specifically. Meanwhile, Loc-lynx1 induced a more significant increase in currents evoked by imidacloprid and epibatidine than Loc-lynx3, and the effects of Loc-lynx1 on imidacloprid and epibatidine were significantly higher than those on acetylcholine. Among three lynx proteins, only Loc-lynx1 significantly increased [(3) H]epibatidine binding on Locα1/β2. The results indicated that Loc-lynx1 had different modulation patterns in nAChRs compared to Loc-lynx2 and Loc-lynx3. Taken together, these findings indicated that three Lynx proteins were nAChR modulators and had selective activities in different nAChRs. Lynx proteins might display their selectivities from three aspects: nAChR subtypes, various agonists and different modulation patterns. Insect Lynx (Ly-6/neurotoxin) proteins act as the allosteric modulators on insect nicotinic acetylcholine receptors (nAChRs), the important targets of insecticides. We found that insect lynx proteins showed their selectivities from at least three aspects: nAChR subtypes, various agonists and different modulation patterns. © 2015 International Society for Neurochemistry.

  5. Gating of long-term potentiation by nicotinic acetylcholine receptors at the cerebellum input stage.

    Directory of Open Access Journals (Sweden)

    Francesca Prestori

    Full Text Available The brain needs mechanisms able to correlate plastic changes with local circuit activity and internal functional states. At the cerebellum input stage, uncontrolled induction of long-term potentiation or depression (LTP or LTD between mossy fibres and granule cells can saturate synaptic capacity and impair cerebellar functioning, which suggests that neuromodulators are required to gate plasticity processes. Cholinergic systems innervating the cerebellum are thought to enhance procedural learning and memory. Here we show that a specific subtype of acetylcholine receptors, the α7-nAChRs, are distributed both in cerebellar mossy fibre terminals and granule cell dendrites and contribute substantially to synaptic regulation. Selective α7-nAChR activation enhances the postsynaptic calcium increase, allowing weak mossy fibre bursts, which would otherwise cause LTD, to generate robust LTP. The local microperfusion of α7-nAChR agonists could also lead to in vivo switching of LTD to LTP following sensory stimulation of the whisker pad. In the cerebellar flocculus, α7-nAChR pharmacological activation impaired vestibulo-ocular-reflex adaptation, probably because LTP was saturated, preventing the fine adjustment of synaptic weights. These results show that gating mechanisms mediated by specific subtypes of nicotinic receptors are required to control the LTD/LTP balance at the mossy fibre-granule cell relay in order to regulate cerebellar plasticity and behavioural adaptation.

  6. Use of Monoclonal Antibodies to Study the Structure and Function of Nicotinic Acetylcholine Receptors on Electric Organ and Muscle and to Determine the Structure of Nicotinic Acetylcholine Receptors on Neurons

    Science.gov (United States)

    1988-03-16

    zebra finches . 5 9 Their primary 20 interest was in the sexually dimorphic song nuclei, which, it turns out, lack substantial amounts of mAb binding...of nicotinic acetylcholine receptors in the brain of the zebra finch (Poephila guttata). J Comp Neurol, in press. 60. Swanson L, 3 Lindstrom, S...several other ligand-gated ion channels. 1 This is summarized in Figure 1. 11 During the past year, we wrote a rather extensive review on molecular

  7. Meningitic Escherichia coli K1 penetration and neutrophil transmigration across the blood-brain barrier are modulated by alpha7 nicotinic receptor.

    Directory of Open Access Journals (Sweden)

    Feng Chi

    Full Text Available Alpha7 nicotinic acetylcholine receptor (nAChR, an essential regulator of inflammation, is abundantly expressed in hippocampal neurons, which are vulnerable to bacterial meningitis. However, it is unknown whether α7 nAChR contributes to the regulation of these events. In this report, an aggravating role of α7 nAChR in host defense against meningitic E. coli infection was demonstrated by using α7-deficient (α7(-/- mouse brain microvascular endothelial cells (BMEC and animal model systems. As shown in our in vitro and in vivo studies, E. coli K1 invasion and polymorphonuclear neutrophil (PMN transmigration across the blood-brain barrier (BBB were significantly reduced in α7(-/- BMEC and α7(-/- mice. Stimulation by nicotine was abolished in the α7(-/- cells and animals. The same blocking effect was achieved by methyllycaconitine (α7 antagonist. The tight junction molecules occludin and ZO-1 were significantly reduced in the brain cortex of wildtype mice infected with E. coli and treated with nicotine, compared to α7(-/- cells and animals. Decreased neuronal injury in the hippocampal dentate gyrus was observed in α7(-/- mice with meningitis. Proinflammatory cytokines (IL-1β, IL-6, TNFα, MCP-1, MIP-1alpha, and RANTES and adhesion molecules (CD44 and ICAM-1 were significantly reduced in the cerebrospinal fluids of the α7(-/- mice with E. coli meningitis. Furthermore, α7 nAChR is the major calcium channel for nicotine- and E. coli K1-increased intracellular calcium concentrations of mouse BMEC. Taken together, our data suggest that α7 nAChR plays a detrimental role in the host defense against meningitic infection by modulation of pathogen invasion, PMN recruitment, calcium signaling and neuronal inflammation.

  8. Development and characterization of the α3β4α5 nicotinic receptor cellular membrane affinity chromatography column and its application for on line screening of plant extracts

    OpenAIRE

    Ciesla, L.; Okine, M.; Rosenberg, A.; Dossou, K.S.S.; Toll, L.; Wainer, I.W.; Moaddel, R.

    2015-01-01

    The α3β4α5 nAChR has been recently shown to be a useful target for smoking cessation pharmacotherapies. Herein, we report on the development and characterization of the α3β4α5 nicotinic receptor column by frontal displacement chromatography. The binding affinity of the nicotine and minor alkaloids found in tobacco smoke condensates were determined for both the α3β4 and α3β4α5 nicotinic receptors. It was demonstrated that while no subtype selectivity was observed for nicot...

  9. Agonist and antagonist effects of tobacco-related nitrosamines on human α4β2 nicotinic acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Simone eBrusco

    2015-09-01

    Full Text Available Regulation of the ‘neuronal’ nicotinic acetylcholine receptors (nAChRs is implicated in both tobacco addiction and smoking-dependent tumor promotion. Some of these effects are caused by the tobacco-derived N-nitrosamines, which are carcinogenic compounds that avidly bind to nAChRs. However, the functional effects of these drugs on specific nAChR subtypes are largely unknown. By using patch-clamp methods, we tested 4-(methylnitrosamine-1-(3-pyridyl-1-butanone (NNK and N’-nitrosonornicotine (NNN on human α4β2 nAChRs. These latter are widely distributed in the mammalian brain and are also frequently expressed outside the nervous system. NNK behaved as a partial agonist, with an apparent EC50 of 16.7 μM. At 100 μM, it activated 16 % of the maximal current activated by nicotine. When NNK was co-applied with nicotine, it potentiated the currents elicited by nicotine concentrations ≤ 100 nM. At higher concentrations of nicotine, NNK always inhibited the α4β2 nAChR. In contrast, NNN was a pure inhibitor of this nAChR subtype, with IC50 of approximately 1 nM in the presence of 10 μM nicotine. The effects of both NNK and NNN were mainly competitive and largely independent of Vm. The different actions of NNN and NNK must be taken into account when interpreting their biological effects in vitro and in vivo.

  10. Nicotine increases impulsivity and decreases willingness to exert cognitive effort despite improving attention in "slacker" rats: insights into cholinergic regulation of cost/benefit decision making.

    Science.gov (United States)

    Hosking, Jay G; Lam, Fred C W; Winstanley, Catharine A

    2014-01-01

    Successful decision making in our daily lives requires weighing an option's costs against its associated benefits. The neuromodulator acetylcholine underlies both the etiology and treatment of a number of illnesses in which decision making is perturbed, including Alzheimer's disease, attention-deficit/hyperactivity disorder, and schizophrenia. Nicotine acts on the cholinergic system and has been touted as a cognitive enhancer by both smokers and some researchers for its attention-boosting effects; however, it is unclear whether treatments that have a beneficial effect on attention would also have a beneficial effect on decision making. Here we utilize the rodent Cognitive Effort Task (rCET), wherein animals can choose to allocate greater visuospatial attention for a greater reward, to examine cholinergic contributions to both attentional performance and choice based on attentional demand. Following the establishment of baseline behavior, four drug challenges were administered: nicotine, mecamylamine, scopolamine, and oxotremorine (saline plus three doses for each). As per previous rCET studies, animals were divided by their baseline preferences, with "worker" rats choosing high-effort/high-reward options more than their "slacker" counterparts. Nicotine caused slackers to choose even fewer high-effort trials than at baseline, but had no effect on workers' choice. Despite slackers' decreased willingness to expend effort, nicotine improved their attentional performance on the task. Nicotine also increased measures of motor impulsivity in all animals. In contrast, scopolamine decreased animals' choice of high-effort trials, especially for workers, while oxotremorine decreased motor impulsivity for all animals. In sum, the cholinergic system appears to contribute to decision making, and in part these contributions can be understood as a function of individual differences. While nicotine has been considered as a cognitive enhancer, these data suggest that its modest

  11. Nicotine Increases Impulsivity and Decreases Willingness to Exert Cognitive Effort despite Improving Attention in “Slacker” Rats: Insights into Cholinergic Regulation of Cost/Benefit Decision Making

    Science.gov (United States)

    Hosking, Jay G.; Lam, Fred C. W.; Winstanley, Catharine A.

    2014-01-01

    Successful decision making in our daily lives requires weighing an option’s costs against its associated benefits. The neuromodulator acetylcholine underlies both the etiology and treatment of a number of illnesses in which decision making is perturbed, including Alzheimer’s disease, attention-deficit/hyperactivity disorder, and schizophrenia. Nicotine acts on the cholinergic system and has been touted as a cognitive enhancer by both smokers and some researchers for its attention-boosting effects; however, it is unclear whether treatments that have a beneficial effect on attention would also have a beneficial effect on decision making. Here we utilize the rodent Cognitive Effort Task (rCET), wherein animals can choose to allocate greater visuospatial attention for a greater reward, to examine cholinergic contributions to both attentional performance and choice based on attentional demand. Following the establishment of baseline behavior, four drug challenges were administered: nicotine, mecamylamine, scopolamine, and oxotremorine (saline plus three doses for each). As per previous rCET studies, animals were divided by their baseline preferences, with “worker” rats choosing high-effort/high-reward options more than their “slacker” counterparts. Nicotine caused slackers to choose even fewer high-effort trials than at baseline, but had no effect on workers’ choice. Despite slackers’ decreased willingness to expend effort, nicotine improved their attentional performance on the task. Nicotine also increased measures of motor impulsivity in all animals. In contrast, scopolamine decreased animals’ choice of high-effort trials, especially for workers, while oxotremorine decreased motor impulsivity for all animals. In sum, the cholinergic system appears to contribute to decision making, and in part these contributions can be understood as a function of individual differences. While nicotine has been considered as a cognitive enhancer, these data suggest

  12. Nicotine increases impulsivity and decreases willingness to exert cognitive effort despite improving attention in "slacker" rats: insights into cholinergic regulation of cost/benefit decision making.

    Directory of Open Access Journals (Sweden)

    Jay G Hosking

    Full Text Available Successful decision making in our daily lives requires weighing an option's costs against its associated benefits. The neuromodulator acetylcholine underlies both the etiology and treatment of a number of illnesses in which decision making is perturbed, including Alzheimer's disease, attention-deficit/hyperactivity disorder, and schizophrenia. Nicotine acts on the cholinergic system and has been touted as a cognitive enhancer by both smokers and some researchers for its attention-boosting effects; however, it is unclear whether treatments that have a beneficial effect on attention would also have a beneficial effect on decision making. Here we utilize the rodent Cognitive Effort Task (rCET, wherein animals can choose to allocate greater visuospatial attention for a greater reward, to examine cholinergic contributions to both attentional performance and choice based on attentional demand. Following the establishment of baseline behavior, four drug challenges were administered: nicotine, mecamylamine, scopolamine, and oxotremorine (saline plus three doses for each. As per previous rCET studies, animals were divided by their baseline preferences, with "worker" rats choosing high-effort/high-reward options more than their "slacker" counterparts. Nicotine caused slackers to choose even fewer high-effort trials than at baseline, but had no effect on workers' choice. Despite slackers' decreased willingness to expend effort, nicotine improved their attentional performance on the task. Nicotine also increased measures of motor impulsivity in all animals. In contrast, scopolamine decreased animals' choice of high-effort trials, especially for workers, while oxotremorine decreased motor impulsivity for all animals. In sum, the cholinergic system appears to contribute to decision making, and in part these contributions can be understood as a function of individual differences. While nicotine has been considered as a cognitive enhancer, these data suggest

  13. Nicotinic acetylcholine receptor β2 subunit gene implicated in a systems-based candidate gene study of smoking cessation

    OpenAIRE

    Conti, DV; Lee, W.; D. Li; Liu, J.; Van Den Berg, D.; Thomas, PD; Bergen, AW; Swan, GE; Tyndale, RF; Benowitz, NL; Lerman, C

    2008-01-01

    Although the efficacy of pharmacotherapy for tobacco dependence has been previously demonstrated, there is substantial variability among individuals in treatment response. We performed a systems-based candidate gene study of 1295 single nucleotide polymorphisms (SNPs) in 58 genes within the neuronal nicotinic receptor and dopamine systems to investigate their role in smoking cessation in a bupropion placebo-controlled randomized clinical trial. Putative functional variants were supplemented w...

  14. A novel in vitro potency assay of antisera against Thai Naja kaouthia based on nicotinic acetylcholine receptor binding

    OpenAIRE

    Ratanabanangkoon, Kavi; Simsiriwong, Pavinee; Pruksaphon, Kritsada; Tan, Kae Yi; Eursakun, Sukanya; Tan, Choo Hock; Chantrathonkul, Bunkuea; Wongwadhunyoo, Wongsakorn; Youngchim, Sirida; Tan, Nget Hong

    2017-01-01

    Snake envenomation is an important medical problem. One of the hurdles in antivenom development is the in vivo assay of antivenom potency which is expensive, gives variable results and kills many animals. We report a novel in vitro assay involving the specific binding of the postsynaptic neurotoxins (PSNTs) of elapid snakes with purified Torpedo californica nicotinic acetylcholine receptor (nAChR). The potency of an antivenom is determined by its antibody ability to bind and neutralize the PS...

  15. α6β2 nicotinic acetylcholine receptors influence locomotor activity and ethanol consumption.

    Science.gov (United States)

    Kamens, Helen M; Peck, Colette; Garrity, Caitlin; Gechlik, Alex; Jenkins, Brenita C; Rajan, Akshat

    2017-06-01

    Nicotinic acetylcholine receptors (nAChRs) in the mesolimbic dopamine system have been implicated in ethanol behaviors. In particular, work in genetically engineered mice has demonstrated that α6-containing nAChRs are involved in ethanol consumption and sedation. A limitation of these studies is that the alteration in the receptor was present throughout development. The recently described α6β2 antagonist, N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI), now makes it possible to test for the involvement of these receptors using a pharmacological approach. The aim of this study was to examine the role of α6β2 nAChRs in ethanol behaviors using a pharmacological approach. Adolescent C57BL/6J mice were treated with bPiDI 30 min prior to testing the mice for binge-like ethanol consumption in the drinking-in-the-dark (DID) test, ethanol-induced motor incoordination using the balance beam, and ethanol-induced sedation using the Loss of Righting Reflex (LORR) paradigm. Adolescent animals were chosen because they express a high amount of α6 mRNA relative to adult animals. Control studies were also performed to determine the effect of bPiDI on locomotor activity and ethanol metabolism. Female mice treated with 20 mg/kg bPiDI had reduced locomotor activity compared to saline-treated animals during the first 30 min following an acute injection. Pretreatment with the α6β2 antagonist reduced adolescent ethanol consumption but also reduced saccharin consumption. No significant effects were observed on ethanol-induced ataxia, sedation, or metabolism. This study provides evidence that α6β2 nAChRs are involved in locomotor activity as well as ethanol and saccharin consumption in adolescent animals. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Autonomic function in mice lacking alpha5 neuronal nicotinic acetylcholine receptor subunit.

    Science.gov (United States)

    Wang, Ningshan; Orr-Urtreger, Avi; Chapman, Joab; Rabinowitz, Ruth; Nachman, Rachel; Korczyn, Amos D

    2002-07-15

    Neuronal acetylcholine nicotinic receptors (nAChR) are composed of 12 subunits (alpha2-10, beta2-4), of which alpha3, alpha5, alpha7, beta2 and beta4 subunits are known to exist in the autonomic nervous system (ANS). alpha5 subunits possess unique biophysical and pharmacological properties. The present study was undertaken to examine the functional role and pharmacological properties of the nAChR alpha5 subunits in the ANS using mice lacking alpha5 nAChR subunits (alpha5-/-). These mice grew to normal size showing no obvious physical or neurological deficit. They also showed normality in thermoregulation, pupil size and resting heart rate under physiological conditions. The heart rate and rectal temperature did not differ between alpha5-/- and wild-type mice during exposure to cold stress. An impairment of cardiac parasympathetic ganglionic transmission was observed during high frequency vagal stimulation, which caused cardiac arrest in all wild-type animals while alpha5-/- mice were more resistant. Deficiency of alpha5 subunits strikingly increased the sensitivity to a low concentration of hexamethonium, leading to a nearly complete blockade of bradycardia in response to vagal stimulation. Such a concentration of hexamethonium only slightly depressed the effects of vagal stimulation in control mice. Deficiency of alpha5 subunits significantly increased ileal contractile responses to cytisine and epibatidine. These results suggest that alpha5 subunits may affect the affinity and sensitivity of agonists and antagonists in the native receptors. Previous studies revealed that alpha5 subunits form functional receptors only in combination with other alpha and beta subunits. Thus, the data presented here imply that alpha5 subunits modulate the activity of nAChR in autonomic ganglia in vivo.

  17. Targeting brain α7 nicotinic acetylcholine receptors in Alzheimer's disease: rationale and current status.

    Science.gov (United States)

    Vallés, Ana Sofía; Borroni, María Virginia; Barrantes, Francisco J

    2014-11-01

    Alzheimer's disease (AD) is the most common form of dementia among older persons. Pathognomonic hallmarks of the disease include the development of amyloid senile plaques and deposits of neurofibrillary tangles. These changes occur in the brain long before the clinical manifestations of AD (cognitive impairment in particular) become apparent. Nicotinic acetylcholine receptors (AChRs), particularly the α7 subtype, are highly expressed in brain regions relevant to cognitive and memory functions and involved in the processing of sensory information. There is strong evidence that implicates the participation of AChRs in AD. This review briefly introduces current strategies addressing the pathophysiologic findings (amyloid-β-peptide plaques, neurofibrillary tangles) and then focuses on more recent efforts of pharmacologic intervention in AD, specifically targeted to the α7 AChR. Whereas cholinesterase inhibitors such as donepezil, galantamine, or rivastigmine, together with the non-competitive N-methyl-D-aspartate receptor antagonist memantine are at the forefront of present-day clinical intervention for AD, new insights into AChR molecular pharmacology are bringing other drugs, directed at AChRs, to center stage. Among these are the positive allosteric modulators that selectively target α7 AChRs and are aimed at unleashing the factors that hinder agonist-mediated, α7 AChR channel activation. This calls for more detailed knowledge of the distribution, functional properties, and involvement of AChRs in various signaling cascades-together with the corresponding abnormalities in all these properties-to be able to engineer strategies in drug design and evaluate the therapeutic possibilities of new compounds targeting this class of neurotransmitter receptors.

  18. Mechanisms of Nicotine Addiction

    Energy Technology Data Exchange (ETDEWEB)

    McGehee, Daniel (University of Chicago)

    2002-06-26

    Nicotine reinforces the use of tobacco products primarily through its interaction with specific receptor proteins within the brain's reward centers. A critical step in the process of addiction for many drugs, including nicotine, is the release of the neurotransmitter dopamine. A single nicotine exposure will enhance dopamine levels for hours, however, nicotinic receptors undergo both activation and then desensitization in minutes, which presents an important problem. How does the time course of receptor activity lead to the prolonged release of dopamine? We have found that persistent modulation of both inhibitory and excitatory synaptic connections by nicotine underlies the sustained increase in dopamine release. Because these inputs express different types of nicotinic receptors there is a coordinated shift in the balance of synaptic inputs toward excitation of the dopamine neurons. Excitatory inputs are turned on while inhibitory inputs are depressed, thereby boosting the brain's reward system.

  19. Binding of Nicotinoids and the Related Compounds to the Insect Nicotinic Acetyicholine Receptor

    National Research Council Canada - National Science Library

    Motohiro TOMIZAWA; Izuru YAMAMOTO

    1992-01-01

    ...) obtained from housefly and honeybee head membranes, nicotine, nornicotine, anabasine and dihydronicotyrine, all with highly basic nitrogen, had a strong binding affinity, whereas myosmine, nicotyrine...

  20. Promoted neuronal differentiation after activation of alpha4/beta2 nicotinic acetylcholine receptors in undifferentiated neural progenitors.

    Directory of Open Access Journals (Sweden)

    Takeshi Takarada

    Full Text Available BACKGROUND: Neural progenitor is a generic term used for undifferentiated cell populations of neural stem, neuronal progenitor and glial progenitor cells with abilities for proliferation and differentiation. We have shown functional expression of ionotropic N-methyl-D-aspartate (NMDA and gamma-aminobutyrate type-A receptors endowed to positively and negatively regulate subsequent neuronal differentiation in undifferentiated neural progenitors, respectively. In this study, we attempted to evaluate the possible functional expression of nicotinic acetylcholine receptor (nAChR by undifferentiated neural progenitors prepared from neocortex of embryonic rodent brains. METHODOLOGY/PRINCIPAL FINDINGS: Reverse transcription polymerase chain reaction analysis revealed mRNA expression of particular nAChR subunits in undifferentiated rat and mouse progenitors prepared before and after the culture with epidermal growth factor under floating conditions. Sustained exposure to nicotine significantly inhibited the formation of neurospheres composed of clustered proliferating cells and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction activity at a concentration range of 1 µM to 1 mM without affecting cell survival. In these rodent progenitors previously exposed to nicotine, marked promotion was invariably seen for subsequent differentiation into cells immunoreactive for a neuronal marker protein following the culture of dispersed cells under adherent conditions. Both effects of nicotine were significantly prevented by the heteromeric α4β2 nAChR subtype antagonists dihydro-β-erythroidine and 4-(5-ethoxy-3-pyridinyl-N-methyl-(3E-3-buten-1-amine, but not by the homomeric α7 nAChR subtype antagonist methyllycaconitine, in murine progenitors. Sustained exposure to nicotine preferentially increased the expression of Math1 among different basic helix-loop-helix proneural genes examined. In undifferentiated progenitors from embryonic mice

  1. Activating α7 nicotinic acetylcholine receptor inhibits NLRP3 inflammasome through regulation of β-arrestin-1.

    Science.gov (United States)

    Ke, Ping; Shao, Bo-Zong; Xu, Zhe-Qi; Chen, Xiong-Wen; Wei, Wei; Liu, Chong

    2017-11-01

    To evaluate whether activating α7 nicotinic acetylcholine receptor (α7nAChR) could inhibit the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome through regulation of β-arrestin-1 in monocyte/macrophage system, thus contributing to the control of neuroinflammation. The protein levels of NLRP3, caspase-1 (Casp-1) p20 and proCasp-1, interleukin-1β (IL-1β) p17 and proIL-1β, IL-18 and proIL-18 were measured using Western blotting. The mRNA levels of Casp-1 and IL-1β were detected by real-time PCR (RT-PCR). The colocalization and interaction of NLRP3 protein and β-arrestin-1 were measured by immunofluorescence staining and immunoprecipitation. The expression of β-arrestin-1 was significantly increased and colocalized with CD45-positive cells in spinal cord of experimental auto-immune encephalomyelitis (EAE) mice when compared with the sham mice, which was attenuated by pretreatment with PNU282987, a specific α7nAChR agonist. PNU282987 also significantly inhibited the activation of NLRP3 inflammasome and thus decreased the production of IL-1β and IL-18 both in lipopolysaccharide (LPS)/ATP-stimulated BV2 microglia in vitro and spinal cord from EAE mice in vivo, while inverse effects were observed in α7nAChR knockout mice. Furthermore, overexpression of β-arrestin-1 attenuated the inhibitory effect of PNU282987 on NLRP3 inflammasome activation in LPS/ATP-stimulated BV2 microglia. PNU282987 inhibited the interaction between β-arrestin-1 and NLRP3 protein in vitro. The present study demonstrates that activating α7nAChR can lead to NLRP3 inflammasome inhibition via regulation of β-arrestin-1 in monocyte/microglia system. © 2017 John Wiley & Sons Ltd.

  2. N-methyl serotonin analogues from the Bufo bufo toad venom interact efficiently with the α7 nicotinic acetylcholine receptors.

    Science.gov (United States)

    Kryukova, E V; Lebedev, D S; Ivanov, I A; Ivanov, D A; Starkov, V G; Tsetlin, V I; Utkin, Yu N

    2017-01-01

    Two low-molecular-weight compounds were isolated from the parotid gland secret of the toad Bufo bufo, which by absorption spectra and HPLC-MS/MS chromatography data correspond to di- and trimethyl derivatives of serotonin (5-hydorxytryptamine): bufotenine (confirmed by counter synthesis) and bufotenidine (5-HTQ). In experiments on competitive radioligand binding, these compounds showed a higher affinity and selectivity for neuronal α7 nicotinic acetylcholine receptors compared with the muscular cholinergic receptors. The most efficient compound in terms of binding value was bufotenine, the efficiency of 5-HTQ was an order of magnitude lower, and the minimal activity was exhibited by serotonin.

  3. Targeted drug delivery system to neural cells utilizes the nicotinic acetylcholine receptor.

    Science.gov (United States)

    Huey, Rachel; O'Hagan, Barry; McCarron, Paul; Hawthorne, Susan

    2017-06-15

    Drug delivery to the brain is still a major challenge in the field of therapeutics, especially for large and hydrophilic compounds. In order to achieve drug delivery of therapeutic concentration in the central nervous system, the problematic blood brain barrier (BBB) must be overcome. This work presents the formulation of a targeted nanoparticle-based drug delivery system using a specific neural cell targeting ligand, rabies virus derived peptide (RDP). Characterization studies revealed that RDP could be conjugated to drug-loaded PLGA nanoparticles of average diameter 257.10±22.39nm and zeta potential of -5.51±0.73mV. In vitro studies showed that addition of RDP to nanoparticles enhanced drug accumulation in a neural cell line specifically as opposed to non-neural cell lines. It was revealed that this drug delivery system is reliant upon nicotinic acetylcholine receptor (nAChR) function for RDP-facilitated effects, supporting a cellular uptake mechanism of action. The specific neural cell targeting capabilities of RDP via the nAChR offers a non-toxic, non-invasive and promising approach to the delivery of therapeutics to the brain. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  4. Effect of Secondhand Smoke on Occupancy of Nicotinic Acetylcholine Receptors in Brain

    Science.gov (United States)

    Brody, Arthur L.; Mandelkern, Mark A.; London, Edythe D.; Khan, Aliyah; Kozman, Daniel; Costello, Matthew R.; Vellios, Evan E.; Archie, Meena M.; Bascom, Rebecca; Mukhin, Alexey G.

    2012-01-01

    Context Despite progress in tobacco control, secondhand smoke (SHS) exposure remains prevalent worldwide and is implicated in the initiation and maintenance of cigarette smoking. Objective To determine whether moderate SHS exposure results in brain α4β2* nicotinic acetylcholine receptor (nAChR) occupancy. Design, Setting, and Participants Positron emission tomography scanning and the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (also known as 2-[18F]fluoro-A-85380, or 2-FA) were used to determine α4β2* nAChR occupancy from SHS exposure in 24 young adult participants (11 moderately dependent cigarette smokers and 13 nonsmokers). Participants underwent two bolus-plus-continuous-infusion 2-FA positron emission tomography scanning sessions during which they sat in the passenger’s seat of a car for 1 hour and either were exposed to moderate SHS or had no SHS exposure. The study took place at an academic positron emission tomography center. Main Outcome Measure Changes induced by SHS in 2-FA specific binding volume of distribution as a measure of α4β2* nAChR occupancy. Results An overall multivariate analysis of variance using specific binding volume of distribution values revealed a significant main effect of condition (SHS vs control) (F1,22=42.5, P cars and other enclosed spaces. PMID:21536968

  5. Early signs of pathological cognitive aging in mice lacking high-affinity nicotinic receptors.

    Directory of Open Access Journals (Sweden)

    Eleni eKonsolaki

    2016-04-01

    Full Text Available In order to address pathological cognitive decline effectively, it is critical to adopt early preventive measures in individuals considered at risk. It is therefore essential to develop approaches that identify such individuals before the onset of irreversible dementia. Α deficient cholinergic system has been consistently implicated as one of the main factors associated with a heightened vulnerability to the aging process. In the present study we used mice lacking high affinity nicotinic receptors (β2-/-, which have been proposed as an animal model of accelerated/premature cognitive aging. Our aim was to identify behavioural signs that could serve as indicators or predictors of impending cognitive decline. We used test batteries in order to assess cognitive functions and additional tasks to investigate spontaneous behaviours, such as species-specific activities and exploration/locomotion in a novel environment. Our data confirm and extend the hypothesis that β2-/- animals exhibit age-related cognitive impairments, manifested in both spatial learning and recognition memory tasks. In addition, we reveal deficits in spontaneous behaviour and habituation processes earlier in life. To our knowledge, this is the first study to perform an extensive behavioural examination of an animal model of premature cognitive aging, and our results suggest that β2-nAChR dependent cognitive deterioration progressively evolves from initial subtle behavioural changes to global dementia due to the combined effect of the neuropathology and aging.

  6. Neuronal Nicotinic Receptors as New Targets for Amphetamine-Induced Oxidative Damage and Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Elena Escubedo

    2011-06-01

    Full Text Available Amphetamine derivatives such as methamphetamine (METH and 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy” are widely abused drugs in a recreational context. This has led to concern because of the evidence that they are neurotoxic in animal models and cognitive impairments have been described in heavy abusers. The main targets of these drugs are plasmalemmal and vesicular monoamine transporters, leading to reverse transport and increased monoamine efflux to the synapse. As far as neurotoxicity is concerned, increased reactive oxygen species (ROS production seems to be one of the main causes. Recent research has demonstrated that blockade of a7 nicotinic acetylcholine receptors (nAChR inhibits METH- and MDMA-induced ROS production in striatal synaptosomes which is dependent on calcium and on NO-synthase activation. Moreover, a7 nAChR antagonists (methyllycaconitine and memantine attenuated in vivo the neurotoxicity induced by METH and MDMA, and memantine prevented the cognitive impairment induced by these drugs. Radioligand binding experiments demonstrated that both drugs have affinity to a7 and heteromeric nAChR, with MDMA showing lower Ki values, while fluorescence calcium experiments indicated that MDMA behaves as a partial agonist on a7 and as an antagonist on heteromeric nAChR. Sustained Ca increase led to calpain and caspase-3 activation. In addition, modulatory effects of MDMA on a7 and heteromeric nAChR populations have been found.

  7. Neonicotinoids target distinct nicotinic acetylcholine receptors and neurons, leading to differential risks to bumblebees

    Science.gov (United States)

    Moffat, Christopher; Buckland, Stephen T.; Samson, Andrew J.; McArthur, Robin; Chamosa Pino, Victor; Bollan, Karen A.; Huang, Jeffrey T.-J.; Connolly, Christopher N.

    2016-04-01

    There is growing concern over the risk to bee populations from neonicotinoid insecticides and the long-term consequences of reduced numbers of insect pollinators to essential ecosystem services and food security. Our knowledge of the risk of neonicotinoids to bees is based on studies of imidacloprid and thiamethoxam and these findings are extrapolated to clothianidin based on its higher potency at nicotinic acetylcholine receptors. This study addresses the specificity and consequences of all three neonicotinoids to determine their relative risk to bumblebees at field-relevant levels (2.5 ppb). We find compound-specific effects at all levels (individual cells, bees and whole colonies in semi-field conditions). Imidacloprid and clothianidin display distinct, overlapping, abilities to stimulate Kenyon cells, indicating the potential to differentially influence bumblebee behavior. Bee immobility was induced only by imidacloprid, and an increased vulnerability to clothianidin toxicity only occurred following chronic exposure to clothianidin or thiamethoxam. At the whole colony level, only thiamethoxam altered the sex ratio (more males present) and only clothianidin increased queen production. Finally, both imidacloprid and thiamethoxam caused deficits in colony strength, while no detrimental effects of clothianidin were observed. Given these findings, neonicotinoid risk needs to be considered independently for each compound and target species.

  8. α7 Nicotinic Receptor Promotes the Neuroprotective Functions of Astrocytes against Oxaliplatin Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Lorenzo Di Cesare Mannelli

    2015-01-01

    Full Text Available Neuropathies are characterized by a complex response of the central nervous system to injuries. Glial cells are recruited to maintain neuronal homeostasis but dysregulated activation leads to pain signaling amplification and reduces the glial neuroprotective power. Recently, we highlighted the property of α7 nicotinic-acetylcholine-receptor (nAChR agonists to relieve pain and induce neuroprotection simultaneously with a strong increase in astrocyte density. Aimed to study the role of α7 nAChR in the neuron-glia cross-talk, we treated primary rat neurons and astrocytes with the neurotoxic anticancer drug oxaliplatin evaluating the effect of the α7 nAChR agonist PNU-282987 (PNU. Oxaliplatin (1 μM, 48 h reduced cell viability and increased caspase-3 activity of neuron monocultures without damaging astrocytes. In cocultures, astrocytes were not able to protect neurons by oxaliplatin even if glial cell metabolism was stimulated (pyruvate increase. On the contrary, the coculture incubation with 10 μM PNU improved neuron viability and inhibited apoptosis. In the absence of astrocytes, the protection disappeared. Furthermore, PNU promoted the release of the anti-inflammatory cytokine TGF-β1 and the expression of the glutamate-detoxifying enzyme glutamine synthetase. The α7 nAChR stimulation protects neurons from oxaliplatin toxicity through an astrocyte-mediated mechanism. α7 nAChR is suggested for recovering the homeostatic role of astrocytes.

  9. Anti-neuropathic effects of Rosmarinus officinalis L. terpenoid fraction: relevance of nicotinic receptors

    Science.gov (United States)

    Mannelli, Lorenzo Di Cesare; Micheli, Laura; Maresca, Mario; Cravotto, Giancarlo; Bellumori, Maria; Innocenti, Marzia; Mulinacci, Nadia; Ghelardini, Carla

    2016-01-01

    Traditional uses and current results highlight the neuroprotective properties of Rosmarinus officinalis L. The compelling need for novel strategies able to relieve neuropathic pain encouraged us to analyze different rosemary leaf extracts in rats following chronic constriction injury (CCI) of sciatic nerve. Ethanol, acetone, and the innovative ultrasound-hexane extractive methods were used to obtain: EE, AE, and for hexane extracts UREprel and URE. Extracts were characterized in terms of typical constituents and repeatedly administered to CCI-rats (13-days treatment, from the day of surgery). URE showed the best efficacy and potency in reducing hypersensitivity to noxious- and non-noxious stimuli and spontaneous pain. URE contained the higher quantity of the terpenoid carnosic acid (CA) and its efficacy was compared to pure CA. Histological analysis of the sciatic nerve revealed that URE prevented axon and myelin derangement, edema and inflammatory infiltrate. In the dorsal horn of the spinal cord, URE did not reduce astrocyte activation. Both the pain reliever and the neuroconservative effects of URE were significantly prevented by the nicotinic receptor (nAChR) antagonist mecamylamine. In conclusion, the hexane-ultrasound rosemary extract is able to reduce neuropathic hypersensitivity and protect nervous tissues. Effectiveness is mainly related to the terpenoid fraction by mechanisms involving nAChRs. PMID:27713514

  10. Nicotinic acetylcholine receptor density in cognitively intact subjects at an early stage of Parkinson's disease.

    Science.gov (United States)

    Isaias, Ioannis Ugo; Spiegel, Jörg; Brumberg, Joachim; Cosgrove, Kelly P; Marotta, Giorgio; Oishi, Naoya; Higuchi, Takahiro; Küsters, Sebastian; Schiller, Markus; Dillmann, Ulrich; van Dyck, Christopher H; Buck, Andreas; Herrmann, Ken; Schloegl, Susanne; Volkmann, Jens; Lassmann, Michael; Fassbender, Klaus; Lorenz, Reinhard; Samnick, Samuel

    2014-01-01

    We investigated in vivo brain nicotinic acetylcholine receptor (nAChR) distribution in cognitively intact subjects with Parkinson's disease (PD) at an early stage of the disease. Fourteen patients and 13 healthy subjects were imaged with single photon emission computed tomography and the radiotracer 5-[(123)I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine ([(123)I]5IA). Patients were selected according to several criteria, including short duration of motor signs (<7 years) and normal scores at an extensive neuropsychological evaluation. In PD patients, nAChR density was significantly higher in the putamen, the insular cortex and the supplementary motor area and lower in the caudate nucleus, the orbitofrontal cortex, and the middle temporal gyrus. Disease duration positively correlated with nAChR density in the putamen ipsilateral (ρ = 0.56, p < 0.05) but not contralateral (ρ = 0.49, p = 0.07) to the clinically most affected hemibody. We observed, for the first time in vivo, higher nAChR density in brain regions of the motor and limbic basal ganglia circuits of subjects with PD. Our findings support the notion of an up-regulated cholinergic activity at the striatal and possibly cortical level in cognitively intact PD patients at an early stage of disease.

  11. Neonicotinoids and Other Insect Nicotinic Receptor Competitive Modulators: Progress and Prospects.

    Science.gov (United States)

    Casida, John E

    2018-01-07

    Neonicotinoids (neonics) are remarkably effective as plant systemics to control sucking insects and for flea control on dogs and cats. The nitroimines imidacloprid, clothianidin, thiamethoxam, and dinotefuran are the leaders among the seven commercial neonics that also include the nitromethylene nitenpyram, the nitromethylene-derived cycloxaprid, and the cyanoimines acetamiprid and thiacloprid. Honey bees are highly sensitive to the nitroimines and nitromethylenes, but the cyanoimines are less toxic. All neonics are nicotinic acetylcholine receptor (nAChR) agonists with a common mode of action, target-site cross-resistance, and much higher potency on insect than mammalian nAChRs at defined binding sites. The structurally related sulfoximine sulfoxaflor and butenolide flupyradifurone are also nAChR agonists, and the mesoionic triflumezopyrim is a nAChR competitive modulator with little or no target-site cross-resistance. Some neonics induce stress tolerance in plants via salicylate-associated systems. The neonics in general are readily metabolized and, except for pollinators, have favorable toxicological profiles.

  12. Stimulation of Alpha7 Nicotinic Acetylcholine Receptor Attenuates Nicotine-Induced Upregulation of MMP, MCP-1, and RANTES through Modulating ERK1/2/AP-1 Signaling Pathway in RAW264.7 and MOVAS Cells

    Directory of Open Access Journals (Sweden)

    Liping Liu

    2017-01-01

    Full Text Available Vagus nerve stimulation through alpha7 nicotine acetylcholine receptors (α7-nAChR signaling had been demonstrated attenuation of inflammation. This study aimed to determine whether PNU-282987, a selective α7-nAChR agonist, affected activities of matrix metalloproteinase (MMP and inflammatory cytokines in nicotine-treatment RAW264.7 and MOVAS cells and to assess the underlying molecular mechanisms. RAW264.7 and MOVAS cells were treated with nicotine at different concentrations (0, 1, 10, and 100 ng/ml for 0–120 min. Nicotine markedly stimulated the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2 and c-Jun in RAW264.7 cells. Pretreatment with U0126 significantly suppressed phosphorylation of ERK1/2 and further attenuated nicotine-induced activation of c-Jun and upregulation of MMP-2, MMP-9, monocyte chemotactic protein- (MCP- 1, and regulated upon activation normal T cell expressed and secreted (RANTES. Similarly, nicotine treatment also increased phosphorylation of c-Jun and expressions of MMP-2, MMP-9, MCP-1, and RANTES in MOVAS cells. When cells were pretreated with PNU-282987, nicotine-induced activations of ERK1/2 and c-Jun in RAW264.7 cells and c-Jun in MOVAS cells were effectively inhibited. Furthermore, nicotine-induced secretions of MMP-2, MMP-9, MCP-1, and RANTES were remarkably downregulated. Treatment with α7-nAChR agonist inhibits nicotine-induced upregulation of MMP and inflammatory cytokines through modulating ERK1/2/AP-1 signaling in RAW264.7 cells and AP-1 in MOVAS cells, providing a new therapeutic for abdominal aortic aneurysm.

  13. Modulation of high- and low-frequency components of the cortical local field potential via nicotinic and muscarinic acetylcholine receptors in anesthetized mice.

    Science.gov (United States)

    Kalmbach, Abigail; Waters, Jack

    2014-01-01

    Release of acetylcholine (ACh) in neocortex is important for learning, memory and attention tasks. The primary source of ACh in neocortex is axons ascending from the basal forebrain. Release of ACh from these axons evokes changes in the cortical local field potential (LFP), including a decline in low-frequency spectral power that is often referred to as desynchronization of the LFP and is thought to result from the activation of muscarinic ACh receptors. Using channelrhodopsin-2, we selectively stimulated the axons of only cholinergic basal forebrain neurons in primary somatosensory cortex of the urethane-anesthetized mouse while monitoring the LFP. Cholinergic stimulation caused desynchronization and two brief increases in higher-frequency power at stimulus onset and offset. Desynchronization (1-6 Hz) was localized, extending ≤ 1 mm from the edge of stimulation, and consisted of both nicotinic and muscarinic receptor-mediated components that were inhibited by mecamylamine and atropine, respectively. Hence we have identified a nicotinic receptor-mediated component to desynchronization. The increase in higher-frequency power (>10 Hz) at stimulus onset was also mediated by activation of nicotinic and muscarinic receptors. However, the increase in higher-frequency power (10-20 Hz) at stimulus offset was evoked by activation of muscarinic receptors and inhibited by activation of nicotinic receptors. We conclude that the activation of nicotinic and muscarinic ACh receptors in neocortex exerts several effects that are reflected in distinct frequency bands of the cortical LFP in urethane-anesthetized mice.

  14. Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist

    Science.gov (United States)

    Johnson, David G.; Ulichny Goebel, Camy; Hruby, Victor J.; Bregman, Marvin D.; Trivedi, Dev

    1982-02-01

    The glucagon analog [l-Nα-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.

  15. The role of nicotinic acetylcholine receptors in autosomal dominant nocturnal frontal lobe epilepsy.

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    Andrea eBecchetti

    2015-02-01

    Full Text Available Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE is a focal epilepsy with attacks typically arising in the frontal lobe during non rapid eye movement (NREM sleep. It is characterized by clusters of complex and stereotyped hypermotor seizures, frequently accompanied by sudden arousals. Cognitive and psychiatric symptoms may be also observed. Approximately 12% of the ADNFLE families carry mutations on genes coding for subunits of the heteromeric neuronal nicotinic receptors (nAChRs. This is consistent with the widespread expression of these receptors, particularly the α4β2* subtype, in the neocortex and thalamus. However, understanding how mutant nAChRs lead to partial frontal epilepsy is far from being straightforward because of the complexity of the cholinergic regulation in both developing and mature brains. The relation with the sleep-waking cycle must be also explained. We discuss some possible pathogenetic mechanisms in the light of recent advances about the nAChR role in prefrontal regions as well as the studies carried out in murine models of ADNFLE. Functional evidence points to alterations in prefrontal GABA release, and the synaptic unbalance probably arises during the cortical circuit maturation. Although most of the available functional evidence concerns mutations on nAChR subunit genes, other genes have been recently implicated in the disease, such as KCNT1 (coding for a Na+-dependent K+ channel, DEPD5 (Dishevelled, Egl-10 and Pleckstrin Domain-containing protein 5, and CRH (Corticotropin-Releasing Hormone. Overall, the uncertainties about both the etiology and the pathogenesis of ADNFLE point to the current gaps in our knowledge the regulation of neuronal networks in the cerebral cortex.

  16. Nicotinic receptor activation by epibatidine induces heme oxygenase-1 and protects chromaffin cells against oxidative stress.

    Science.gov (United States)

    Egea, Javier; Rosa, Angelo O; Cuadrado, Antonio; García, Antonio G; López, Manuela G

    2007-09-01

    Activation of neuronal nicotinic acetylcholine receptors (nAChR) provides neuroprotection against different toxic stimuli that often lead to overproduction of reactive oxygen species (ROS) and cell death. ROS production has been related with disease progression in several neurodegenerative pathologies such as Alzheimer's or Parkinson's diseases. In this context, we investigated here if the exposure of bovine chromaffin cells to the potent nAChR agonist epibatidine protected against rotenone (30 micromol/L) plus oligomycin (10 micromol/L) (rot/oligo) toxicity, an in vitro model of mitochondrial ROS production. Epibatidine induced a concentration- and time-dependent protection, which was maximal at 3 mumol/L after 24 h. Pre-incubation with dantrolene (100 micromol/L) (a blocker of the ryanodine receptor channel), chelerythrine (1 micromol/L) (a protein kinase C inhibitor), or PD98059 (50 micromol/L) (a MEK inhibitor), aborted epibatidine-elicited cytoprotection. Mitochondrial depolarization, ROS, and caspase 3 active produced by rot/oligo were also prevented by epibatidine. Epibatidine doubled the amount of heme oxygenase-1 (HO-1), a critical cell defence enzyme against oxidative stress. Furthermore, the HO-1 inhibitor Sn(IV) protoporphyrin IX dichloride reversed the epibatidine protecting effects and HO-1 inducer Co (III) protoporphyrin IX dichloride exhibited neuroprotective effects by itself. The results of this study point to HO-1 as the cytoprotective target of nAChR activation through the following pathway: endoplasmic reticulum Ca(2+)-induced Ca(2+)-release activates the protein kinase C/extracellular regulated kinase/HO-1 axis to mitigate mitochondrial depolarization and ROS production. This study provides a mechanistic insight on how nAChR activation translates into an antioxidant and antiapoptotic signal through up-regulation of HO-1.

  17. Nicotinic receptors and lurasidone-mediated reversal of phencyclidine-induced deficit in novel object recognition.

    Science.gov (United States)

    Miyauchi, Masanori; Neugebauer, Nichole M; Oyamada, Yoshihiro; Meltzer, Herbert Y

    2016-03-15

    Enhancement of cholinergic function via nicotinic acetylcholine (ACh) receptor (nAChR) agonism is a potential approach for the treatment of cognitive impairment associated with schizophrenia (CIAS). Some atypical antipsychotic drugs (AAPDs) enhance ACh release in rodent brain, indirectly stimulating these receptors. Here, we elucidate which nAChR subtypes mediate novel object recognition (NOR) in normal rats and contribute to the ability of the AAPD, lurasidone, to improve the NOR deficit in sub-chronic (sc) phencyclidine (PCP)-treated rats, a model for CIAS. The ability of lurasidone and nAChR ligands to reverse the scPCP-induced deficit in NOR was assessed in female, Long-Evans rats. The broad acting nAChR antagonist, mecamylamine (MEC), induced a NOR deficit in normal rats. The NOR deficit secondary to scPCP was reversed by either selective α4β2* nAChR agonism (A-85380) or α7 nAChRs agonism (PNU-282987); these effects were blocked by DHβE and MLA, selective antagonists of α4β2* and α7 nAChR, respectively. The ability of lurasidone to reverse the scPCP-induced NOR deficit was blocked by MEC, but not MLA or DHβE. However, sub-effective doses (SED) of either A-85380 or PNU-282987 potentiated the ability of SED lurasidone to reverse the scPCP-induced NOR deficit. These results identify both α4β2* and α7 nAChRs as candidates for enhancing the ability of lurasidone and other AAPDs, which increase the release of ACh, to improve CIAS. Copyright © 2016. Published by Elsevier B.V.

  18. Nicotinic receptor Alpha7 expression during tooth morphogenesis reveals functional pleiotropy.

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    Scott W Rogers

    Full Text Available The expression of nicotinic acetylcholine receptor (nAChR subtype, alpha7, was investigated in the developing teeth of mice that were modified through homologous recombination to express a bi-cistronic IRES-driven tau-enhanced green fluorescent protein (GFP; alpha7GFP or IRES-Cre (alpha7Cre. The expression of alpha7GFP was detected first in cells of the condensing mesenchyme at embryonic (E day E13.5 where it intensifies through E14.5. This expression ends abruptly at E15.5, but was again observed in ameloblasts of incisors at E16.5 or molar ameloblasts by E17.5-E18.5. This expression remains detectable until molar enamel deposition is completed or throughout life as in the constantly erupting mouse incisors. The expression of alpha7GFP also identifies all stages of innervation of the tooth organ. Ablation of the alpha7-cell lineage using a conditional alpha7Cre×ROSA26-LoxP(diphtheria toxin A strategy substantially reduced the mesenchyme and this corresponded with excessive epithelium overgrowth consistent with an instructive role by these cells during ectoderm patterning. However, alpha7knock-out (KO mice exhibited normal tooth size and shape indicating that under normal conditions alpha7 expression is dispensable to this process. The function of ameloblasts in alpha7KO mice is altered relative to controls. High resolution micro-computed tomography analysis of adult mandibular incisors revealed enamel volume of the alpha7KO was significantly reduced and the organization of enamel rods was altered relative to controls. These results demonstrate distinct and varied spatiotemporal expression of alpha7 during tooth development, and they suggest that dysfunction of this receptor would have diverse impacts upon the adult organ.

  19. Colorimetric microtiter plate receptor-binding assay for the detection of freshwater and marine neurotoxins targeting the nicotinic acetylcholine receptors

    Science.gov (United States)

    Rubio, Fernando; Kamp, Lisa; Carpino, Justin; Faltin, Erin; Loftin, Keith A.; Molgó, Jordi; Aráoz, Rómulo

    2014-01-01

    Anatoxin-a and homoanatoxin-a, produced by cyanobacteria, are agonists of nicotinic acetylcholine receptors (nAChRs). Pinnatoxins, spirolides, and gymnodimines, produced by dinoflagellates, are antagonists of nAChRs. In this study we describe the development and validation of a competitive colorimetric, high throughput functional assay based on the mechanism of action of freshwater and marine toxins against nAChRs. Torpedo electrocyte membranes (rich in muscle-type nAChR) were immobilized and stabilized on the surface of 96-well microtiter plates. Biotinylated α-bungarotoxin (the tracer) and streptavidin-horseradish peroxidase (the detector) enabled the detection and quantitation of anatoxin-a in surface waters and cyclic imine toxins in shellfish extracts that were obtained from different locations across the US. The method compares favorably to LC/MS/MS and provides accurate results for anatoxin-a and cyclic imine toxins monitoring. Study of common constituents at the concentrations normally found in drinking and environmental waters, as well as the tolerance to pH, salt, solvents, organic and inorganic compounds did not significantly affect toxin detection. The assay allowed the simultaneous analysis of up to 25 samples within 3.5 h and it is well suited for on-site or laboratory monitoring of low levels of toxins in drinking, surface, and ground water as well as in shellfish extracts.

  20. Nicotine affects bone resorption and suppresses the expression of cathepsin K, MMP-9 and vacuolar-type H(+-ATPase d2 and actin organization in osteoclasts.

    Directory of Open Access Journals (Sweden)

    Hideki Tanaka

    Full Text Available Tobacco smoking is an important risk factor for the development of several cancers, osteoporosis, and inflammatory diseases such as periodontitis. Nicotine is one of the major components of tobacco. In previous study, we showed that nicotine inhibits mineralized nodule formation by osteoblasts, and the culture medium from osteoblasts containing nicotine and lipopolysaccharide increases osteoclast differentiation. However, the direct effect of nicotine on the differentiation and function of osteoclasts is poorly understood. Thus, we examined the direct effects of nicotine on the expression of nicotine receptors and bone resorption-related enzymes, mineral resorption, actin organization, and bone resorption using RAW264.7 cells and bone marrow cells as osteoclast precursors. Cells were cultured with 10(-5, 10(-4, or 10(-3 M nicotine and/or 50 µM α-bungarotoxin (btx, an 7 nicotine receptor antagonist, in differentiation medium containing the soluble RANKL for up 7 days. 1-5, 7, 9, and 10 nicotine receptors were expressed on RAW264.7 cells. The expression of 7 nicotine receptor was increased by the addition of nicotine. Nicotine suppressed the number of tartrate-resistant acid phosphatase positive multinuclear osteoclasts with large nuclei(≥10 nuclei, and decreased the planar area of each cell. Nicotine decreased expression of cathepsin K, MMP-9, and V-ATPase d2. Btx inhibited nicotine effects. Nicotine increased CA II expression although decreased the expression of V-ATPase d2 and the distribution of F-actin. Nicotine suppressed the planar area of resorption pit by osteoclasts, but did not affect mineral resorption. These results suggest that nicotine increased the number of osteoclasts with small nuclei, but suppressed the number of osteoclasts with large nuclei. Moreover, nicotine reduced the planar area of resorption pit by suppressing the number of osteoclasts with large nuclei, V-ATPase d2, cathepsin K and MMP-9 expression and actin

  1. Activation of the Torpedo nicotinic acetylcholine receptor. The contribution of residues alphaArg55 and gammaGlu93.

    Science.gov (United States)

    Kapur, Ankur; Davies, Martin; Dryden, William F; Dunn, Susan M J

    2006-03-01

    The Torpedo nicotinic acetylcholine receptor is a heteropentamer (alpha2betagammadelta) in which structurally homologous subunits assemble to form a central ion pore. Viewed from the synaptic cleft, the likely arrangement of these subunits is alpha-gamma-alpha-delta-beta lying in an anticlockwise orientation. High affinity binding sites for agonists and competitive antagonists have been localized to the alpha-gamma and alpha-delta subunit interfaces. We investigated the involvement of amino acids lying at an adjacent interface (gamma-alpha) in receptor properties. Recombinant Torpedo receptors, expressed in Xenopus oocytes, were used to investigate the consequences of mutating alphaArg55 and gammaGlu93, residues that are conserved in most species of the peripheral nicotinic receptors. Based on homology modeling, these residues are predicted to lie in close proximity to one another and it has been suggested that they may form a salt bridge in the receptor's three-dimensional structure (Sine et al. 2002 J Biol Chem277, 29 210-29 223). Although substitution of alphaR55 by phenylalanine or tryptophan resulted in approximately a six-fold increase in the EC50 value for acetylcholine activation, the charge reversal mutation (alphaR55E) had no significant effect. In contrast, the replacement of gammaE93 by an arginine conferred an eight-fold increase in the potency for acetylcholine-induced receptor activation. In the receptor carrying the double mutations, alphaR55E-gammaE93R or alphaR55F-gammaE93R, the potency for acetylcholine activation was partially restored to that of the wild-type. The results suggest that, although individually these residues influence receptor activation, direct interactions between them are unlikely to play a major role in the stabilization of different conformational states of the receptor.

  2. Development and characterization of the α3β4α5 nicotinic receptor cellular membrane affinity chromatography column and its application for on line screening of plant extracts.

    Science.gov (United States)

    Ciesla, L; Okine, M; Rosenberg, A; Dossou, K S S; Toll, L; Wainer, I W; Moaddel, R

    2016-01-29

    The α3β4α5 nAChR has been recently shown to be a useful target for smoking cessation pharmacotherapies. Herein, we report on the development and characterization of the α3β4α5 nicotinic receptor column by frontal displacement chromatography. The binding affinity of the nicotine and minor alkaloids found in tobacco smoke condensates were determined for both the α3β4 and α3β4α5 nicotinic receptors. It was demonstrated that while no subtype selectivity was observed for nicotine and nornicotine, anabasine was selective for the α3β4α5 nicotinic receptor. The non-competitive inhibitor binding site was also studied and it was demonstrated while mecamylamine was not selective between subtypes, buproprion showed subtype selectivity for the α3β4 nicotinic receptor. The application of this methodology to complex mixtures was then carried out by screening aqueous-alcoholic solutions of targeted plant extracts, including Lycopodium clavatum L. (Lycopodiaceae) and Trigonella foenum graecum L. (Fabaceae) against both the α3β4 and α3β4α5 nAChRs. Published by Elsevier B.V.

  3. Acetylcholine release in mouse hippocampal CA1 preferentially activates inhibitory-selective interneurons via alpha4 beta2* nicotinic receptor activation

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    L. Andrew Bell

    2015-04-01

    Full Text Available Acetylcholine (ACh release onto nicotinic receptors directly activates subsets of inhibitory interneurons in hippocampal CA1. However, the specific interneurons activated and their effect on the hippocampal network is not completely understood. Therefore, we investigated subsets of hippocampal CA1 interneurons that respond to ACh release through the activation of nicotinic receptors and the potential downstream effects this may have on hippocampal CA1 network function. ACh was optogenetically released in mouse hippocampal slices by expressing the excitatory optogenetic protein oChIEF-tdTomato in medial septum/diagonal band of Broca cholinergic neurons using Cre recombinase-dependent adeno-associated viral mediated transfection. The actions of optogenetically released ACh were assessed on both pyramidal neurons and different interneuron subtypes via whole cell patch clamp methods. Vasoactive intestinal peptide (VIP-expressing interneurons that selectively innervate other interneurons (VIP/IS were excited by ACh through the activation of nicotinic receptors containing alpah4 and beta2 subunits (alpha4 beta2*. ACh release onto VIP/IS was presynaptically inhibited by M2 muscarinic autoreceptors. ACh release produced spontaneous inhibitory postsynaptic current (sIPSC barrages blocked by dihydro-beta-erythroidine in interneurons but not pyramidal neurons. Optogenetic suppression of VIP interneurons did not inhibit these sIPSC barrages suggesting other interneuron-selective interneurons were also excited by 42* nicotinic receptor activation. In contrast, interneurons that innervate pyramidal neuron perisomatic regions were not activated by ACh release onto nicotinic receptors. Therefore, we propose ACh release in CA1 facilitates disinhibition through activation of 42* nicotinic receptors on interneuron-selective interneurons whereas interneurons that innervate pyramidal neurons are less affected by nicotinic receptor activation.

  4. Cholinergic modulation of the medial prefrontal cortex: the role of nicotinic receptors in attention and regulation of neuronal activity

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    Bernard eBloem

    2014-03-01

    Full Text Available Acetylcholine release in the medial prefrontal cortex is (mPFC crucial for normal cognitive performance. Despite the fact that many have studied how acetylcholine affects neuronal processing in the mPFC and thereby influences attention behavior, there is still a lot unknown about how this occurs. Here we will review the evidence that cholinergic modulation of the mPFC plays a role in attention and we will summarize the current knowledge about the role between acetylcholine receptors and behavior and how acetylcholine receptor activation changes processing in the cortical microcircuitry. Recent evidence implicates fast phasic release of acetylcholine in cue detection and attention. This review will focus mainly on the fast ionotropic nicotinic receptors and less on the metabotropic muscarinic receptors. Finally, we will review limitations of the existing studies and address how innovative technologies might push the field forward in order to gain understanding into the relation between acetylcholine, neuronal activity and behavior.

  5. Ameliorative effect of nicotine exposure on insulin resistance is accompanied by decreased cardiac glycogen synthase kinase-3 and plasminogen activator inhibitor-1 during oral oestrogen-progestin therapy.

    Science.gov (United States)

    Michael, Olugbenga S; Olatunji, Lawrence A

    2017-09-03

    Cigarette smoking is considered to be a major risk factor for the development of diabetes and cardiovascular disease. Oestrogen-progestin combined oral contraceptive (COC) use has been associated with adverse cardiometabolic events. We hypothesized that nicotine would ameliorate insulin resistance (IR) that is accompanied by decreased cardiac glycogen synthase kinase-3 (GSK-3) and plasminogen activator inhibitor-1 (PAI-1). Female Wistar rats received (po) low-(0.1 mg/kg) or high-nicotine (1.0 mg/kg) with or without COC containing 5.0 µg levonorgestrel plus 1.0 µg ethinylestradiol daily for 8 weeks. Data showed that COC treatment or nicotine exposure led to IR, glucose deregulation, atherogenic dyslipidemia, increased corticosterone, aldosterone, cardiac and circulating GSK-3 values and PAI-1. However, these effects with the exception of corticosterone and aldosterone were ameliorated in COC + nicotine-exposed rats. Amelioration of IR induced by COC treatment is accompanied by decreased circulating PAI-1, cardiac PAI-1 and GSK-3 instead of circulating aldosterone and corticosterone.

  6. Insulin decreases atherosclerosis by inducing endothelin receptor B expression

    DEFF Research Database (Denmark)

    Park, Kyoungmin; Mima, Akira; Li, Qian

    2016-01-01

    ) in the endothelia of Apoe(-/-) mice (Irs1/Apoe(-/-)) increased insulin signaling and function in the aorta. Atherosclerosis was significantly reduced in Irs1/ApoE(-/-) mice on diet-induced hyperinsulinemia and hyperglycemia. The mechanism of insulin's enhanced antiatherogenic actions in EC was related to remarkable......Endothelial cell (EC) insulin resistance and dysfunction, caused by diabetes, accelerates atherosclerosis. It is unknown whether specifically enhancing EC-targeted insulin action can decrease atherosclerosis in diabetes. Accordingly, overexpressing insulin receptor substrate-1 (IRS1...... induction of NO action, which increases endothelin receptor B (EDNRB) expression and intracellular [Ca(2+)]. Using the mice with knockin mutation of eNOS, which had Ser1176 mutated to alanine (AKI), deleting the only known mechanism for insulin to activate eNOS/NO pathway, we observed that IRS1...

  7. Activation of the dorsal hippocampal nicotinic acetylcholine receptors improves tamoxifen-induced memory retrieval impairment in adult female rats.

    Science.gov (United States)

    Tajik, Azam; Rezayof, Ameneh; Ghasemzadeh, Zahra; Sardari, Maryam

    2016-07-07

    Tamoxifen (TAM), a selective estrogen receptor modulator, has frequently been used in the treatment of breast cancer. In view of the fact that cognitive deficits in women who receive adjuvant chemotherapy for breast cancer is a common health problem, using female animal models for investigating the cognitive effects of TAM administration may improve our knowledge of TAM therapy. Therefore, the present study assessed the role of dorsal hippocampal cholinergic nicotinic receptors (nAChRs) in the effect of TAM administration on memory retrieval in ovariectomized (OVX) and non-OVX female rats using a passive avoidance learning task. Our results showed that pre-test administration of TAM (2-6mg/kg) impaired memory retrieval. Pre-test intra-CA1 microinjection of nicotine (0.3-0.5μg/rat) reversed TAM-induced memory impairment. Pre-test intra-CA1 microinjection of mecamylamine (0.1-0.3μg/rat) plus 2mg/kg (an ineffective dose) of TAM impaired memory retrieval. Pre-test intra-CA1 microinjection of the same doses of nicotine and mecamylamine by themselves had no effect on memory retrieval. In OVX rats, the administration of TAM (6mg/kg) produced memory impairment but pre-test intra-CA1 microinjection of nicotine (0.5μg/rat) had no effect on TAM response. Moreover, the administration of an ineffective dose of TAM (2mg/kg) had no effect on memory retrieval in OVX rats, while pre-test intra-CA1 microinjection of mecamylamine (0.3μg/rat) impaired memory retrieval. Taken together, it can be concluded that the impairing effect of TAM on memory formation may be modulated by nAChRs of the CA1 regions. It seems that memory impairment may be considered as an important side effect of TAM. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Acute Ethanol Administration Upregulates Synaptic α4-Subunit of Neuronal Nicotinic Acetylcholine Receptors within the Nucleus Accumbens and Amygdala

    Directory of Open Access Journals (Sweden)

    Josephine R. Tarren

    2017-10-01

    Full Text Available Alcohol and nicotine are two of the most frequently abused drugs, with their comorbidity well described. Previous data show that chronic exposure to nicotine upregulates high-affinity nicotinic acetylcholine receptors (nAChRs in several brain areas. Effects of ethanol on specific brain nAChR subtypes within the mesolimbic dopaminergic (DA pathway may be a key element in the comorbidity of ethanol and nicotine. However, it is unknown how alcohol affects the abundance of these receptor proteins. In the present study, we measured the effect of acute binge ethanol on nAChR α4 subunit levels in the prefrontal cortex (PFC, nucleus accumbens (NAc, ventral tegmental area (VTA, and amygdala (Amg by western blot analysis using a knock-in mouse line, generated with a normally functioning α4 nAChR subunit tagged with yellow fluorescent protein (YFP. We observed a robust increase in α4-YFP subunit levels in the NAc and the Amg following acute ethanol, with no changes in the PFC and VTA. To further investigate whether this upregulation was mediated by increased local mRNA transcription, we quantified mRNA levels of the Chrna4 gene using qRT-PCR. We found no effect of ethanol on α4 mRNA expression, suggesting that the upregulation of α4 protein rather occurs post-translationally. The quantitative counting of YFP immunoreactive puncta further revealed that α4-YFP protein is upregulated in presynaptic boutons of the dopaminergic axons projecting to the shell and the core regions of the NAc as well as to the basolateral amygdala (BLA, but not to the central or lateral Amg. Together, our results demonstrate that a single exposure to binge ethanol upregulates level of synaptic α4∗ nAChRs in dopaminergic inputs to the NAc and BLA. This upregulation could be linked to the functional dysregulation of dopaminergic signalling observed during the development of alcohol dependence.

  9. Combined α7 nicotinic acetylcholine receptor agonism and partial serotonin transporter inhibition produce antidepressant-like effects in the mouse forced swim and tail suspension tests

    DEFF Research Database (Denmark)

    Andreasen, Jesper T; Redrobe, John P; Nielsen, Elsebet Ø

    2012-01-01

    Emerging evidence points to an involvement of nicotinic acetylcholine receptors (nAChRs) in major depression. Nicotine improves symptoms of depression in humans and shows antidepressant-like effects in rodents. Monoamine release is facilitated by nAChR stimulation, and nicotine-evoked serotonin (5...... represents a compound displaying the synergistic effect of α7 nAChR agonism combined with partial 5-HT reuptake inhibition previously described. The addition of α7 nAChR agonism to classical monoamine-based mechanisms may represent a novel option for the improved treatment of major depression....

  10. Pharmacological profile of Ascaris suum ACR-16, a new homomeric nicotinic acetylcholine receptor widely distributed in Ascaris tissues.

    Science.gov (United States)

    Abongwa, Melanie; Buxton, Samuel K; Courtot, Elise; Charvet, Claude L; Neveu, Cédric; McCoy, Ciaran J; Verma, Saurabh; Robertson, Alan P; Martin, Richard J

    2016-08-01

    Control of nematode parasite infections relies largely on anthelmintic drugs, several of which act on nicotinic ACh receptors (nAChRs), and there are concerns about the development of resistance. There is an urgent need for development of new compounds to overcome resistance and novel anthelmintic drug targets. We describe the functional expression and pharmacological characterization of a homomeric nAChR, ACR-16, from a nematode parasite. Using RT-PCR, molecular cloning and two-electrode voltage clamp electrophysiology, we localized acr-16 mRNA in Ascaris suum (Asu) and then cloned and expressed acr-16 cRNA in Xenopus oocytes. Sensitivity of these receptors to cholinergic anthelmintics and a range of nicotinic agonists was tested. Amino acid sequence comparison with vertebrate nAChR subunits revealed ACR-16 to be most closely related to α7 receptors, but with some striking distinctions. acr-16 mRNA was recovered from Asu somatic muscle, pharynx, ovijector, head and intestine. In electrophysiological experiments, the existing cholinergic anthelmintic agonists (morantel, levamisole, methyridine, thenium, bephenium, tribendimidine and pyrantel) did not activate Asu-ACR-16 (except for a small response to oxantel). Other nAChR agonists: nicotine, ACh, cytisine, 3-bromocytisine and epibatidine, produced robust current responses which desensitized at a rate varying with the agonists. Unlike α7, Asu-ACR-16 was insensitive to α-bungarotoxin and did not respond to genistein or other α7 positive allosteric modulators. Asu-ACR-16 had lower calcium permeability than α7 receptors. We suggest that ACR-16 has diverse tissue-dependent functions in nematode parasites and is a suitable drug target for development of novel anthelmintic compounds. © 2016 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

  11. Cotinine antagonizes the behavioral effects of nicotine exposure in the planarian Girardia tigrina.

    Science.gov (United States)

    Bach, Daniel J; Tenaglia, Matthew; Baker, Debra L; Deats, Sean; Montgomery, Erica; Pagán, Oné R

    2016-10-06

    Nicotine is one of the most addictive drugs abused by humans. Our laboratory and others have demonstrated that nicotine decreases motility and induces seizure-like behavior in planarians (pSLM, which are vigorous writhing and bending of the body) in a concentration-dependent manner. Nicotine also induces withdrawal-like behaviors in these worms. Cotinine is the major nicotine metabolite in humans, although it is not the final product of nicotine metabolism. Cotinine is mostly inactive in vertebrate nervous systems and is currently being explored as a molecule which possess most of nicotine's beneficial effects and few of its undesirable ones. It is not known whether cotinine is a product of nicotine metabolism in planarians. We found that cotinine by itself does not seem to elicit any behavioral effects in planarians up to a concentration of 1mM. We also show that cotinine antagonizes the aforementioned nicotine-induced motility decrease and also decreases the expression of nicotine-induced pSLMs in a concentration-dependent manner. Also cotinine prevents the manifestation of some of the withdrawal-like behaviors induced by nicotine in our experimental organism. Thus, we obtained evidence supporting that cotinine antagonizes nicotine in this planarian species. Possible explanations include competitive binding of both compounds at overlapping binding sites, at different nicotinic receptor subtypes, or maybe allosteric interactions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Insights into the structural determinants required for high-affinity binding of chiral cyclopropane-containing ligands to α4β2-nicotinic acetylcholine receptors: an integrated approach to behaviorally active nicotinic ligands

    NARCIS (Netherlands)

    Zhang, H.K.; Eaton, J.B.; Yu, L.F.; Nys, M; Mazzolari, A; van Elk, R.; Smit, A.B.; Alexandrov, V; Hanania, T; Sabath, E; Fedolak, A; Brunner, D; Lukas, R.J.; Vistoli, G; Ulens, C.; Kozikowski, A.P.

    2012-01-01

    Structure-based drug design can potentially accelerate the development of new therapeutics. In this study, a cocrystal structure of the acetylcholine binding protein (AChBP) from Capitella teleta (Ct) in complex with a cyclopropane-containing selective α4β2-nicotinic acetylcholine receptor (nAChR)

  13. Pharmacological characterisation of α6β4* nicotinic acetylcholine receptors assembled from three different α6/α3 subunit chimeras in tsA201 cells

    DEFF Research Database (Denmark)

    Jensen, Anne Bjørnskov; Hoestgaard-Jensen, Kirsten; Jensen, Anders A.

    2014-01-01

    should be made keeping the molecular modifications in the α6 surrogate subunits in mind, this study sheds light on the pharmacological properties of α6β4⁎ nicotinic acetylcholine receptors and demonstrates the applicability of the C6F223L and C16F223L chimeras for studies of these receptors....

  14. Activation of nicotinic α(7) acetylcholine receptor enhances long term potentation in wild type mice but not in APP(swe)/PS1ΔE9 mice

    DEFF Research Database (Denmark)

    Söderman, Andreas; Mikkelsen, Jens D; West, Mark J

    2011-01-01

    Amyloid β (Aβ) plays a central role in Alzheimer's disease (AD) and binds to the nicotinic α(7) receptor (α(7) nAChR). Little is known about the degree to which the binding of Aβ to the α(7) nAChR influences the role of this receptor in long-term potentiation (LTP), however. We have studied the e...

  15. Reward, Addiction, Withdrawal to Nicotine

    Science.gov (United States)

    De Biasi, Mariella; Dani, John A.

    2011-01-01

    Nicotine is the principle addictive component that drives continued tobacco use despite users’ knowledge of the harmful consequences. The initiation of addiction involves the mesocorticolimbic dopamine system, which contributes to the processing of rewarding sensory stimuli during the overall shaping of successful behaviors. Acting mainly through nicotinic receptors containing the α4 and β2 subunits, often in combination with the α6 subunit, nicotine increases the firing rate and the phasic bursts by midbrain dopamine neurons. Neuroadaptations arise during chronic exposure to nicotine, producing an altered brain condition that requires the continued presence of nicotine to be maintained. When nicotine is removed, a withdrawal syndrome develops. The expression of somatic withdrawal symptoms depends mainly on the α5, α2, and β4 nicotinic subunits involving the epithalamic habenular complex and its targets. Thus, nicotine taps into diverse neural systems and an array of nicotinic acetylcholine receptor (nAChR) subtypes to influence reward, addiction, and withdrawal. PMID:21438686

  16. A model for short alpha-neurotoxin bound to nicotinic acetylcholine receptor from Torpedo californica.

    Science.gov (United States)

    Mordvintsev, Dmitry Y; Polyak, Yakov L; Kuzmine, Dmitry A; Levtsova, Olga V; Tourleigh, Yegor V; Kasheverov, Igor E

    2006-01-01

    Short- and long-chain alpha-neurotoxins from snake venoms are potent blockers of nicotinic acetylcholine receptors (nAChRs). Short alpha-neurotoxins consist of 60-62 amino acid residues and include 4 disulfide bridges, whereas long alpha-neurotoxins have 66-75 residues and 5 disulfides. The spatial structure of these toxins is built by three loops, I-III "fingers," confined by four disulfide bridges; the fifth disulfide of long-chain alpha-neurotoxins is situated close to the tip of central loop II. An accurate knowledge of the mode of alpha-neurotoxin-nAChR interaction is important for rational design of new nAChR agonists and antagonists for medical purposes. Ideas on the topography of toxin-nAChR complexes were based until recently on nAChR interactions with selectively labeled alpha-neurotoxins, mutations in toxins, nAChR, or both. Recently, crystal structures have been solved for the Torpedo marmorata nAChR (4A[Unwin, 2005]) and for the acetylcholine-binding protein (AChBP) complexed with mollusk alpha-conotoxin (2.4 A[Celie et al., 2005]) or alpha-cobratoxin, long-chain alpha-neurotoxin (4 A [Bourne et al., 2005]). However, there were no angstrom-resolution models for complexes of short-chain alpha-neurotoxins. Here, we report the model of the Torpedo californica nAChR extracellular domain complexed to a short-chain alpha-neurotoxin II (NTII) from Naja oxiana cobra venom.

  17. 3-Pyridyl ethers as SPECT radioligands for imaging nicotinic acetylcholine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, D.J.; Eberl, S.; Thomson, S.; Smith, A.; Allan, R.D.; Fulham, M.J.; Loiacono, R.; Kassiou, M. E-mail: mkassiou@med.usyd.edu.au

    2004-05-01

    To develop a suitable single photon emission computed tomography (SPECT) radioligand for neuronal nicotinic acetylcholine receptors (nAChRs) that displays faster in vivo kinetics than 5-[{sup 123}I]iodo-A-85380, we synthesised the radioiodinated analogue of A-84543. 5-[{sup 123}I]Iodo-A-84543 was prepared by electrophilic iododestannylation in a modest yield of 23%. In the baboon brain, 5-[{sup 123}I]iodo-A-85380 displayed a profile consistent with the known distribution of nAChRs, however, 5-[{sup 123}I]iodo-A-84543 displayed a homogenous uptake with no preferential localisation in regions known to contain nAChRs. To examine the effect of halogen substitution on the 3-pyridyl ether, A-84543, the 5-chloro, 5-bromo and 5-iodo analogues were synthesised and evaluated with respect to nAChR binding. In vitro binding data revealed that halogen substitution at the 5-position of A-84543 was not well tolerated with an increase in halogen size resulting in lower binding towards nAChRs. The 5-chloro analogue 4 displayed highest affinity, K{sub i}=1.3 nM, compared to the 5-bromo and 5-iodo compounds, 5 K{sub i}=3.3 nM and 3 K{sub i}=40.8 nM, respectively. Taken together, these results clearly indicate that 5-[{sup 123}I]iodo-A-84543 is not suitable for the study of nAChRs in vivo using SPECT.

  18. Molecular-Dynamics Simulations of ELIC a Prokaryotic Homologue of the Nicotinic Acetylcholine Receptor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xiaolin [ORNL; Ivanov, Ivaylo N [ORNL; Wang, Hailong [Mayo Clinic College of Medicine; McCammon, Jonathan [ORNL

    2009-01-01

    The ligand-gated ion channel from Erwinia chrysanthemi (ELIC) is a prokaryotic homolog of the eukaryotic nicotinic acetylcholine receptor (nAChR) that responds to the binding of neurotransmitter acetylcholine and mediates fast signal transmission. ELIC is similar to the nAChR in its primary sequence and overall subunit organization, but despite their structural similarity, it is not clear whether these two ligand-gated ion channels operate in a similar manner. Further, it is not known to what extent mechanistic insights gleaned from the ELIC structure translate to eukaryotic counterparts such as the nAChR. Here we use molecular-dynamics simulations to probe the conformational dynamics and hydration of the transmembrane pore of ELIC. The results are compared with those from our previous simulation of the human ?7 nAChR. Overall, ELIC displays increased stability compared to the nAChR, whereas the two proteins exhibit remarkable similarity in their global motion and flexibility patterns. The majority of the increased stability of ELIC does not stem from the deficiency of the models used in the simulations, and but rather seems to have a structural basis. Slightly altered dynamical correlation features are also observed among several loops within the membrane region. In sharp contrast to the nAChR, ELIC is completely dehydrated from the pore center to the extracellular end throughout the simulation. Finally, the simulation of an ELIC mutant substantiates the important role of F246 on the stability, hydration and possibly function of the ELIC channel.

  19. Hippocampal α7-nicotinic cholinergic receptors modulate memory reconsolidation: a potential strategy for recovery from amnesia.

    Science.gov (United States)

    Blake, M G; Boccia, M M; Krawczyk, M C; Baratti, C M

    2013-11-01

    When subjects are exposed to new learning experiences, the novel information could be acquired and eventually stored through memory consolidation process. The exposure of mice to a novel experience (a hole-board) after being trained in an inhibitory avoidance apparatus is followed by impaired performance of the avoidance memory in subsequent tests. The same impairing effect is produced when mice are exposed to the novel environment after the reactivation of the avoidance memory. This interfering effect is due to impaired consolidation or reconsolidation of the avoidance memory. The administration of the α7-nicotinic receptor agonist choline (Ch) in the dorsal hippocampus (0.8 μg/hippocampus) immediately after the inhibitory avoidance memory reactivation, allowed memory recovery. This effect of Ch was time-dependent, and retention performance was not affected in drug-treated mice that were not subjected to memory reactivation, suggesting that the effects on performance are not due to non-specific effects of the drug. The effects of Ch also depended on the age of the reactivated memory. Altogether, our results suggest that Ch exerts its effects by modulating memory reconsolidation, and that the memory impairment induced by new learning is a memory expression failure and not a storage deficit. Therefore, reconsolidation, among other functions, might serve to change whether a memory will be expressed in later tests. Summarizing, our results open new avenues about the behavioral significance and the physiological functions of memory reconsolidation, providing new strategies for recovering memories from some types of amnesia. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Nicotine Induces Podocyte Apoptosis through Increasing Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Xiqian Lan

    Full Text Available Cigarette smoking plays an important role in the progression of chronic kidney disease (CKD. Nicotine, one of the major components of cigarette smoking, has been demonstrated to increase proliferation of renal mesangial cells. In this study, we examined the effect of nicotine on podocyte injury.To determine the expression of nicotinic acetylcholine receptors (nAChR subunits in podocytes, cDNAs and cell lysate of cultured human podocytes were used for the expression of nAChR mRNAs and proteins, respectively; and mouse renal cortical sections were subjected to immunofluorescant staining. We also studied the effect of nicotine on podocyte nephrin expression, reactive oxygen species (ROS generation (via DCFDA loading followed by fluorometric analysis, proliferation, and apoptosis (morphologic assays. We evaluated the effect of nicotine on podocyte downstream signaling including phosphorylation of ERK1/2, JNK, and p38 and established causal relationships by using respective inhibitors. We used nAChR antagonists to confirm the role of nicotine on podocyte injury.Human podocytes displayed robust mRNA and protein expression of nAChR in vitro studies. In vivo studies, mice renal cortical sections revealed co-localization of nAChRs along with synaptopodin. In vitro studies, nephrin expression in podocyte was decreased by nicotine. Nicotine stimulated podocyte ROS generation; nonetheless, antioxidants such as N-acetyl cysteine (NAC and TEMPOL (superoxide dismutase mimetic agent inhibited this effect of nicotine. Nicotine did not modulate proliferation but promoted apoptosis in podocytes. Nicotine enhanced podocyte phosphorylation of ERK1/2, JNK, and p38, and their specific inhibitors attenuated nicotine-induced apoptosis. nAChR antagonists significantly suppressed the effects of nicotine on podocyte.Nicotine induces podocyte apoptosis through ROS generation and associated downstream MAPKs signaling. The present study provides insight into molecular

  1. Nicotine aversion: Neurobiological mechanisms and relevance to tobacco dependence vulnerability

    Science.gov (United States)

    Fowler, Christie D.; Kenny, Paul J.

    2013-01-01

    Nicotine stimulates brain reward circuitries, most prominently the mesocorticolimbic dopamine system, and this action is considered critical in establishing and maintaining the tobacco smoking habit. Compounds that attenuate nicotine reward are considered promising therapeutic candidates for tobacco dependence, but many of these agents have other actions that limit their potential utility. Nicotine is also highly noxious, particularly at higher doses, and aversive reactions to nicotine after initial exposure can decrease the likelihood of developing a tobacco habit in many first time smokers. Nevertheless, relatively little is known about the mechanisms of nicotine aversion. The purpose of this review is to present recent new insights into the neurobiological mechanisms that regulate avoidance of nicotine. First, the role of the mesocorticolimbic system, so often associated with nicotine reward, in regulating nicotine aversion is highlighted. Second, genetic variation that modifies noxious responses to nicotine and thereby influences vulnerability to tobacco dependence, in particular variation in the CHRNA5-CHRNA3-CHRNB4 nicotinic acetylcholine receptor (nAChR) subunit gene cluster, will be discussed. Third, the role of the habenular complex in nicotine aversion, primarily medial habenular projections to the interpeduncular nucleus (IPN) but also lateral habenular projections to rostromedial tegmental nucleus (RMTg) and ventral tegmental area (VTA) are reviewed. Forth, brain circuits that are enriched in nAChRs, but whose role in nicotine avoidance has not yet been assessed, will be proposed. Finally, the feasibility of developing novel therapeutic agents for tobacco dependence that act not by blocking nicotine reward but by enhancing nicotine avoidance will be considered. PMID:24055497

  2. Cannabinoid CB2 Receptor Mediates Nicotine-Induced Anti-Inflammation in N9 Microglial Cells Exposed to β Amyloid via Protein Kinase C

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    Ji Jia

    2016-01-01

    Full Text Available Background. Reducing β amyloid- (Aβ- induced microglial activation is considered to be effective in treating Alzheimer’s disease (AD. Nicotine attenuates Aβ-induced microglial activation; the mechanism, however, is still elusive. Microglia could be activated into classic activated state (M1 state or alternative activated state (M2 state; the former is cytotoxic and the latter is neurotrophic. In this investigation, we hypothesized that nicotine attenuates Aβ-induced microglial activation by shifting microglial M1 to M2 state, and cannabinoid CB2 receptor and protein kinase C mediate the process. Methods. We used Aβ1–42 to activate N9 microglial cells and observed nicotine-induced effects on microglial M1 and M2 biomarkers by using western blot, immunocytochemistry, and enzyme-linked immunosorbent assay (ELISA. Results. We found that nicotine reduced the levels of M1 state markers, including inducible nitric oxide synthase (iNOS expression and tumor necrosis factor α (TNF-α and interleukin- (IL- 6 releases; meanwhile, it increased the levels of M2 state markers, including arginase-1 (Arg-1 expression and brain-derived neurotrophic factor (BDNF release, in the Aβ-stimulated microglia. Coadministration of cannabinoid CB2 receptor antagonist or protein kinase C (PKC inhibitor partially abolished the nicotine-induced effects. Conclusion. These findings indicated that cannabinoid CB2 receptor mediates nicotine-induced anti-inflammation in microglia exposed to Aβ via PKC.

  3. The Novel, Nicotinic Alpha7 Receptor Partial Agonist, BMS-933043, Improves Cognition and Sensory Processing in Preclinical Models of Schizophrenia.

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    Linda J Bristow

    Full Text Available The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we characterized the novel agent, (2R-N-(6-(1H-imidazol-1-yl-4-pyrimidinyl-4'H-spiro[4-azabicyclo[2.2.2]octane-2,5'-[1,3]oxazol]-2'-amine (BMS-933043, in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat and 0.29 micromolar (human. BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM. BMS-933043 treatment i improved 24 hour novel object recognition memory in mice (0.1-10 mg/kg, sc, ii reversed MK-801-induced deficits in Y maze performance in mice (1-10 mg/kg, sc and set shift performance in rats (1-10 mg/kg, po and iii reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1-3 mg/kg, po. BMS-933043 also improved auditory gating (0.56-3 mg/kg, sc and mismatch negativity (0.03-3 mg/kg, sc in rats treated with S(+ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.

  4. Insulin decreases atherosclerosis by inducing endothelin receptor B expression

    DEFF Research Database (Denmark)

    Park, Kyoungmin; Mima, Akira; Li, Qian

    2016-01-01

    Endothelial cell (EC) insulin resistance and dysfunction, caused by diabetes, accelerates atherosclerosis. It is unknown whether specifically enhancing EC-targeted insulin action can decrease atherosclerosis in diabetes. Accordingly, overexpressing insulin receptor substrate-1 (IRS1......) in the endothelia of Apoe(-/-) mice (Irs1/Apoe(-/-)) increased insulin signaling and function in the aorta. Atherosclerosis was significantly reduced in Irs1/ApoE(-/-) mice on diet-induced hyperinsulinemia and hyperglycemia. The mechanism of insulin's enhanced antiatherogenic actions in EC was related to remarkable...... overexpression in the endothelia of Aki/ApoE(-/-) mice significantly decreased atherosclerosis. Interestingly, endothelial EDNRB expression was selectively reduced in intima of arteries from diabetic patients and rodents. However, endothelial EDNRB expression was upregulated by insulin via P13K/Akt pathway...

  5. Biophysical and ion channel functional characterization of the Torpedo californica nicotinic acetylcholine receptor in varying detergent-lipid environments.

    Science.gov (United States)

    Asmar-Rovira, Guillermo A; Asseo-García, Aloysha M; Quesada, Orestes; Hanson, Michael A; Cheng, Anchi; Nogueras, Carlos; Lasalde-Dominicci, José A; Stevens, Raymond C

    2008-05-01

    The nicotinic acetylcholine receptor (nAChR) of Torpedo electric rays has been extensively characterized over the last three decades. However, high-resolution structural studies have been hampered by the lack of mechanistic molecular models that describe how detergents influence membrane protein stability and function. Furthermore, elucidation of the dynamic detergent-lipid-protein interactions of solubilized membrane proteins is a largely unexplored research field. This study examines the effects of nine detergents on: (1) nAChR-lipid composition (gas chromatography with flame ionization; GC-FID and/or mass selective detectors; GC-MSD), (2) stability and aggregation state (analytical size exclusion chromatography; A-SEC and electron microscopy; EM) and (3) ion channel function (planar lipid bilayers). Detergent solubilization of nAChR-enriched membranes did not result in significant native lipid depletion or destabilization. Upon purification, native lipid depletion occurred in all detergents, with lipid-analogue detergents CHAPS {(3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate}, FC-12 (n-dodecylphosphocholine) and sodium cholate (3alpha,7alpha,12alpha-trihydroxy-5beta-cholan-24-oic acid) maintaining stability and supporting ion channel function, and non-lipid-analogue detergents Cymal-6 (6-cyclohexyl-1-hexyl-beta-D-maltoside), DDM (n-dodecyl-beta-D-maltopyranoside), LDAO (lauryldimethylamine-N-oxide) and OG (n-octyl-beta-d-glucopyranoside) decreasing stability and significantly reducing or completely suppressing ion channel function. Anapoe-C(12)E(9 )(polyoxyethylene-[9]-dodecyl ether) and BigCHAP (N,N'-bis-[3-d-gluconamidopropyl] cholamide) retained residual amounts of native lipid, maintaining moderate stability and ion channel function compared to lipid-analogue detergents. Therefore, the nAChR can be stable and functional in lipid-analogue detergents or in detergents that retain moderate amounts of residual native lipids, but not in non

  6. Calcium-dependent effect of the thymic polypeptide thymopoietin on the desensitization of the nicotinic acetylcholine receptor

    Energy Technology Data Exchange (ETDEWEB)

    Revah, F.; Mulle, C.; Pinset, C.; Audhya, T.; Goldstein, G.; Changeux, J.P.

    1987-05-01

    The effects of the thymic polypeptide thymopoietin (Tpo) on the properties of the nicotinic acetylcholine receptor (AcChoR) were investigated by patch clamp techniques on mouse C/sub 2/ myotubes and by biochemical assays on AcChoR-rich membrane fragments purified from the Torpedo marmorata electric organ. At high concentrations (> 100 nM), Tpo inhibits the binding of cholinergic agonists to the AcChoR in a Ca/sup 2 +/-insensitive manner. At lower concentrations (2 nM), Tpo applied on C/sub 2/ myotubes simultaneously with nondesensitizing concentrations of acetylcholine results in the appearance of long closed times separating groups of openings. This effect depends on the presence of Ca/sup 2 +/ in the external medium. Outside-out recordings, performed with various concentrations of EGTA in the intracellular medium, suggest that Ca/sup 2 +/ acts on the cytoplasmic face of the membrane after entry through acetylcholine-activated channels. Parallel studies with T. marmorata AcChoR-rich membranes show that in the presence of Ca/sup 2 +/ Tpo causes a decrease in the apparent equilibrium dissociation constant of the noncompetitive blocker (/sup 3/H)phencyclidine, enhances, at low concentrations, the binding of (/sup 3/H)acetylcholine, and also alters the binding kinetics of the fluorescent agonist 6-(5-dimethylamino-1-naphthalenesulfonamido)-n-hexanoic acid ..beta..-(N-trimethylammonium bromide) ethyl ester to the AcChoR. It was concluded that, in the presence of Ca/sup 2 +/, Tpo displaces the conformational equilibrium of the AcChoR towards a high-affinity desensitized state and increases the transition rate towards the same state.

  7. Mechanisms involved in nicotinic acetylcholine receptor-induced neurotransmitter release from sympathetic nerve terminals in the mouse vas deferens.

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    Damian J Williams

    Full Text Available Prejunctional nicotinic acetylcholine receptors (nAChRs amplify postganglionic sympathetic neurotransmission, and there are indications that intraterminal Ca(2+ stores might be involved. However, the mechanisms by which nAChR activation stimulates neurotransmitter release at such junctions is unknown. Rapid local delivery (picospritzing of the nAChR agonist epibatidine was combined with intracellular sharp microelectrode recording to monitor spontaneous and field-stimulation-evoked neurotransmitter release from sympathetic nerve terminals in the mouse isolated vas deferens. Locally applied epibatidine (1 µM produced 'epibatidine-induced depolarisations' (EIDs that were similar in shape to spontaneous excitatory junction potentials (SEJPs and were abolished by nonselective nAChR antagonists and the purinergic desensitizing agonist α,β-methylene ATP. The amplitude distribution of EIDs was only slightly shifted towards lower amplitudes by the selective α7 nAChR antagonists α-bungarotoxin and methyllcaconitine, the voltage-gated Na(+ channel blocker tetrodotoxin or by blocking voltage-gated Ca(2+ channels with Cd(2+. Lowering the extracellular Ca(2+ concentration reduced the frequency of EIDs by 69%, but more surprisingly, the Ca(2+-induced Ca(2+ release blocker ryanodine greatly decreased the amplitude (by 41% and the frequency of EIDs by 36%. Ryanodine had no effect on electrically-evoked neurotransmitter release, paired-pulse facilitation, SEJP frequency, SEJP amplitude or SEJP amplitude distribution. These results show that activation of non-α7 nAChRs on sympathetic postganglionic nerve terminals induces high-amplitude junctional potentials that are argued to represent multipacketed neurotransmitter release synchronized by intraterminal Ca(2+-induced Ca(2+ release, triggered by Ca(2+ influx directly through the nAChR. This nAChR-induced neurotransmitter release can be targeted pharmacologically without affecting spontaneous or electrically

  8. Metformin increases hepatic leptin receptor and decreases steatosis in mice.

    Science.gov (United States)

    Tang, Xuemei; Li, Jingwen; Xiang, Wei; Cui, Ye; Xie, Bin; Wang, Xiaodong; Xu, Zihui; Gan, Lixia

    2016-08-01

    In addition to the ascertained efficacy as antidiabetic drug, metformin is increasingly being used as weight-loss agent in obesity, and as insulin sensitizer in nonalcoholic fatty liver disease (NAFLD). However, the mechanisms underlying these effects are still incompletely understood. Emerging evidence suggest metformin as leptin sensitizer to mediate the weight-loss effect in the brain. In this study, we investigated effects of metformin on expression of leptin receptors in liver and kidney in mice. C57BL/6 mice were fed with chow diet (CD) or high-fat diet (HF) for 5months. Afterward, mice were treated with metformin (50mg/kg or 200mg/kg) for 15days. Metabolic parameters and hepatic gene expression were analyzed at the end of the treatment. We also tested the effects of metformin on plasma-soluble leptin receptor (sOB-R) levels in newly diagnosed type 2 diabetes mellitus (T2DM) patients, and assessed its effect on hepatosteatosis in mice. Results showed that metformin upregulates the expression of leptin receptors (OB-Ra, -Rb, -Rc, and -Rd) in liver but not kidney. The stimulation effect is dose-dependent in both chow and HF mice. Upregulation of OB-Rb, long signaling isoform, needs a relatively higher dose of metformin. This effect was paralleled by increased sOBR levels in mice and T2DM patients, and decreased hepatic triglyceride (TG) content and lipogenic gene expression, including sterol regulatory element-binding protein 1c (SREBP-1c), fatty acid synthase (FAS) and acetyl-CoA carboxylase-1 (ACC-1). Taken together, these data identify hepatic leptin receptor as target gene being upregulated by metformin which may enhance leptin sensitivity in liver to alleviate steatosis. © 2016 Society for Endocrinology.

  9. Radiosynthesis and preliminary evaluation of Z.W.-90 and Z.W.-110, two novel acetylenic pyridines for imaging the nicotinic receptors

    Energy Technology Data Exchange (ETDEWEB)

    Kassiou, M.; Giboureau, N. [Sydney Univ., Brain and Mind Research Institute, NSW (Australia); Chellapan, S.; Wei, Z.L.; Kozikowski, A. [Illinois Univ., Chicago, Dept. of Medicinal Chemistry and Pharmacognosy, IL (United States); Henderson, D.; Fulton, R. [RPAH Sydney, Dept. PET and Nuclear Medicine (Australia); Xiao, Y.; Kellar, K. [Georgetown Univ., Dept. of Pharmacology, School of Medicine, Washington, DC (United States); Guilloteau, D.; Emond, P. [Institut National de la Sante et de la Recherche Medicale (INSERM), U619, 37 - Tours (France); Dolle, F. [Service Hospitalier Frederic Joliot, CEA/DSV, Institut d' Imagerie BioMedicale, 91 - Orsay (France)

    2008-02-15

    Central nicotinic acetylcholine receptors (n.A.Ch.R.s) have been implicated in learning memory processes and neuro-psychiatric disorders. Recently it was reported that the introduction of a substituted alkynyl group into the C-5 position of the pyridinyl ring of A-84543, significantly increased the selectivity for the n.A.Ch.R. containing {beta}{sub 2} subunits over {beta}{sub 4} subunits. Two selected candidates, Z.W.-90 and Z.W.-110 were labelled with carbon{sup 11} and evaluated in vivo.{sup 11}C Z.W.-90 penetrated rapidly into the brain, with maximum uptake in the thalamus and cerebellum 2 min post injection followed by clearance. The washout from cerebellum was faster than from thalamus, suggesting that specific binding can be optimally measured at 20 min post injection; Pretreatment of the baboon with nicotine resulted in markedly decreased uptake of the radioligand. {sup 11}C Z.W.-110 also penetrated rapidly into the brain, with a high evident uptake in the thalamus within 5 min. Surprisingly there was also considerable uptake in the striatum. Pretreatment with nicotine resulted in inhibition of uptake of 8 and 1%, in the thalamus and cerebellum, respectively. In pretreatment studies using unlabelled Z.W.-110, 32% inhibition of radioligand uptake was observed in the thalamus and striatum while uptake in the cerebellum was reduced by 24 %.While further work will be necessary in the development of optimal imaging agents for n.A.Ch.Rs, efforts will be made to examine the potential of these newly developed radioligands to serve diagnostic agents in the early detection of neurological disorders. (N.C.)

  10. Investigating the influence of PFC transection and nicotine on dynamics of AMPA and NMDA receptors of VTA dopaminergic neurons

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    Chen Ting

    2011-10-01

    Full Text Available Abstract Background All drugs of abuse, including nicotine, activate the mesocorticolimbic system that plays critical roles in nicotine reward and reinforcement development and triggers glutamatergic synaptic plasticity on the dopamine (DA neurons in the ventral tegmental area (VTA. The addictive behavior and firing pattern of the VTA DA neurons are thought to be controlled by the glutamatergic synaptic input from prefrontal cortex (PFC. Interrupted functional input from PFC to VTA was shown to decrease the effects of the drug on the addiction process. Nicotine treatment could enhance the AMPA/NMDA ratio in VTA DA neurons, which is thought as a common addiction mechanism. In this study, we investigate whether or not the lack of glutamate transmission from PFC to VTA could make any change in the effects of nicotine. Methods We used the traditional AMPA/NMDA peak ratio, AMPA/NMDA area ratio, and KL (Kullback-Leibler divergence analysis method for the present study. Results Our results using AMPA/NMDA peak ratio showed insignificant difference between PFC intact and transected and treated with saline. However, using AMPA/NMDA area ratio and KL divergence method, we observed a significant difference when PFC is interrupted with saline treatment. One possible reason for the significant effect that the PFC transection has on the synaptic responses (as indicated by the AMPA/NMDA area ratio and KL divergence may be the loss of glutamatergic inputs. The glutamatergic input is one of the most important factors that contribute to the peak ratio level. Conclusions Our results suggested that even within one hour after a single nicotine injection, the peak ratio of AMPA/NMDA on VTA DA neurons could be enhanced.

  11. Probing the structure of the affinity-purified and lipid-reconstituted torpedo nicotinic acetylcholine receptor.

    Science.gov (United States)

    Hamouda, Ayman K; Chiara, David C; Blanton, Michael P; Cohen, Jonathan B

    2008-12-02

    The Torpedo nicotinic acetylcholine receptor (nAChR) is the only member of the Cys-loop superfamily of ligand-gated ion channels (LGICs) that is available in high abundance in a native membrane preparation. To study the structure of the other LGICs using biochemical and biophysical techniques, detergent solubilization, purification, and lipid reconstitution are usually required. To assess the effects of purification on receptor structure, we used the hydrophobic photoreactive probe 3-trifluoromethyl-3-(m-[(125)I]iodophenyl)diazirine ([(125)I]TID) to compare the state-dependent photolabeling of the Torpedo nAChR before and after purification and reincorporation into lipid. For the purified nAChR, the agonist-sensitive photolabeling within the M2 ion channel domain of positions M2-6, M2-9, and M2-13, the agonist-enhanced labeling of deltaThr274 (deltaM2-18) within the delta subunit helix bundle, and the labeling at the lipid-protein interface (alphaMu4) were the same as for the nAChR in native membranes. However, addition of agonist did not enhance [(125)I]TID photolabeling of deltaIle288 within the deltaM2-M3 loop. These results indicate that after purification and reconstitution of the Torpedo nAChR, the difference in structure between the resting and desensitized states within the M2 ion channel domain was preserved, but not the agonist-dependent change of structure of the deltaM2-M3 loop. To further characterize the pharmacology of [(125)I]TID binding sites in the nAChR in the desensitized state, we examined the effect of phencyclidine (PCP) on [(125)I]TID photolabeling. PCP inhibited [(125)I]TID labeling of amino acids at the cytoplasmic end of the ion channel (M2-2 and M2-6) while potentiating labeling at M2-9 and M2-13 and allosterically modulating the labeling of amino acids within the delta subunit helix bundle.

  12. Muscle-type nicotinic receptor blockade by diethylamine, the hydrophilic moiety of lidocaine

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    Armando eAlberola-Die

    2016-02-01

    Full Text Available Lidocaine bears in its structure both an aromatic ring and a terminal amine, which can be protonated at physiological pH, linked by an amide group. Since lidocaine causes multiple inhibitory actions on nicotinic acetylcholine receptors (nAChRs, this work was aimed to determine the inhibitory effects of diethylamine (DEA, a small molecule resembling the hydrophilic moiety of lidocaine, on Torpedo marmorata nAChRs microtransplanted to Xenopus oocytes. Similarly to lidocaine, DEA reversibly blocked acetylcholine-elicited currents (IACh in a dose-dependent manner (IC50 close to 70 μM, but unlike lidocaine, DEA did not affect IACh desensitization. IACh inhibition by DEA was more pronounced at negative potentials, suggesting an open-channel blockade of nAChRs, although roughly 30% inhibition persisted at positive potentials, indicating additional binding sites outside the pore. DEA block of nAChRs in the resting state (closed channel was confirmed by the enhanced IACh inhibition when pre-applying DEA before its co-application with ACh, as compared with solely DEA and ACh co-application. Virtual docking assays provide a plausible explanation to the experimental observations in terms of the involvement of different sets of drug binding sites. So, at the nAChR transmembrane (TM domain, DEA and lidocaine shared binding sites within the channel pore, giving support to their open-channel blockade; besides, lidocaine, but not DEA, interacted with residues at cavities among the M1, M2, M3 and M4 segments of each subunit and also at intersubunit crevices. At the extracellular (EC domain, DEA and lidocaine binding sites were broadly distributed, which aids to explain the closed channel blockade observed. Interestingly, some DEA clusters were located at the α-γ interphase of the EC domain, in a cavity near the orthosteric binding site pocket; by contrast, lidocaine contacted with all α-subunit loops conforming the ACh binding site, both in α-γ and

  13. Computer modeling of binding of diverse weak toxins to nicotinic acetylcholine receptors.

    Science.gov (United States)

    Mordvitsev, D Yu; Polyak, Ya L; Kuzmin, D A; Levtsova, O V; Tourleigh, Ye V; Utkin, Yu N; Shaitan, K V; Tsetlin, V I

    2007-04-01

    Weak toxins are the "three-fingered" snake venoms toxins grouped together by having an additional disulfide in the N-terminal loop I. In general, weak toxins have low toxicity, and biological targets have been identified for some of them only, recently by detecting the effects on the nicotinic acetylcholine receptors (nAChR). Here the methods of docking and molecular dynamics simulations are used for comparative modeling of the complexes between four weak toxins of known spatial structure (WTX, candoxin, bucandin, gamma-bungarotoxin) and nAChRs. WTX and candoxin are those toxins whose blocking of the neuronal alpha7- and muscle-type nAChR has been earlier shown in binding assays and electrophysiological experiments, while for the other two toxins no such activity has been reported. Only candoxin and WTX are found here to give stable solutions for the toxin-nAChR complexes. These toxins appear to approach the binding site similarly to short alpha-neurotoxins, but their final position resembles that of alpha-cobratoxin, a long alpha-neurotoxin, in the complex with the acetylcholine-binding protein. The final spatial structures of candoxin and WTX complexes with the alpha7 neuronal or muscle-type nAChR are very similar and do not provide immediate answer why candoxin has a much higher affinity than WTX, but both of them share a virtually irreversible mode of binding to one or both these nAChR subtypes. Possible explanation comes from docking and MD simulations which predict fast kinetics of candoxin association with nAChR, no gross changes in the toxin conformation (with smaller toxin flexibility on alpha7 nAChR), while slow WTX binding to nAChR is associated with slow irreversible rearrangement both of the tip of the toxin loop II and of the binding pocket residues locking finally the toxin molecule. Computer modeling showed that the additional disulfide in the loop I is not directly involved in receptor binding of WTX and candoxin, but it stabilizes the structure of

  14. The nicotinic acetylcholine receptor gene family of the silkworm, Bombyx mori

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    Zhang Chuan-Xi

    2007-09-01

    Full Text Available Abstract Background Nicotinic acetylcholine receptors (nAChRs mediate fast synaptic cholinergic transmission in the insect central nervous system. The insect nAChR is the molecular target of a class of insecticides, neonicotinoids. Like mammalian nAChRs, insect nAChRs are considered to be made up of five subunits, coded by homologous genes belonging to the same family. The nAChR subunit genes of Drosophila melanogaster, Apis mellifera and Anopheles gambiae have been cloned previously based on their genome sequences. The silkworm Bombyx mori is a model insect of Lepidoptera, among which are many agricultural pests. Identification and characterization of B. mori nAChR genes could provide valuable basic information for this important family of receptor genes and for the study of the molecular mechanisms of neonicotinoid action and resistance. Results We searched the genome sequence database of B. mori with the fruit fly and honeybee nAChRs by tBlastn and cloned all putative silkworm nAChR cDNAs by reverse transcriptase-polymerase chain reaction (RT-PCR and rapid amplification of cDNA ends (RACE methods. B. mori appears to have the largest known insect nAChR gene family to date, including nine α-type subunits and three β-type subunits. The silkworm possesses three genes having low identity with others, including one α and two β subunits, α9, β2 and β3. Like the fruit fly and honeybee counterparts, silkworm nAChR gene α6 has RNA-editing sites, and α4, α6 and α8 undergo alternative splicing. In particular, alternative exon 7 of Bmα8 may have arisen from a recent duplication event. Truncated transcripts were found for Bmα4 and Bmα5. Conclusion B. mori possesses a largest known insect nAChR gene family characterized to date, including nine α-type subunits and three β-type subunits. RNA-editing, alternative splicing and truncated transcripts were found in several subunit genes, which might enhance the diversity of the gene family.

  15. Identification of Propofol Binding Sites in a Nicotinic Acetylcholine Receptor with a Photoreactive Propofol Analog*

    Science.gov (United States)

    Jayakar, Selwyn S.; Dailey, William P.; Eckenhoff, Roderic G.; Cohen, Jonathan B.

    2013-01-01

    Propofol, a widely used intravenous general anesthetic, acts at anesthetic concentrations as a positive allosteric modulator of γ-aminobutyric acid type A receptors and at higher concentration as an inhibitor of nicotinic acetylcholine receptors (nAChRs). Here, we characterize propofol binding sites in a muscle-type nAChR by use of a photoreactive analog of propofol, 2-isopropyl-5-[3-(trifluoromethyl)-3H-diazirin-3-yl]phenol (AziPm). Based upon radioligand binding assays, AziPm stabilized the Torpedo nAChR in the resting state, whereas propofol stabilized the desensitized state. nAChR-rich membranes were photolabeled with [3H]AziPm, and labeled amino acids were identified by Edman degradation. [3H]AziPm binds at three sites within the nAChR transmembrane domain: (i) an intrasubunit site in the δ subunit helix bundle, photolabeling in the nAChR desensitized state (+agonist) δM2-18′ and two residues in δM1 (δPhe-232 and δCys-236); (ii) in the ion channel, photolabeling in the nAChR resting, closed channel state (−agonist) amino acids in the M2 helices (αM2-6′, βM2-6′ and -13′, and δM2-13′) that line the channel lumen (with photolabeling reduced by >90% in the desensitized state); and (iii) at the γ-α interface, photolabeling αM2-10′. Propofol enhanced [3H]AziPm photolabeling at αM2-10′. Propofol inhibited [3H]AziPm photolabeling within the δ subunit helix bundle at lower concentrations (IC50 = 40 μm) than it inhibited ion channel photolabeling (IC50 = 125 μm). These results identify for the first time a single intrasubunit propofol binding site in the nAChR transmembrane domain and suggest that this is the functionally relevant inhibitory binding site. PMID:23300078

  16. Molecular determinants of subtype-selective efficacies of cytisine and the novel compound NS3861 at heteromeric nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Harpsøe, Kasper; Hald, Helle; Timmermann, Daniel B

    2013-01-01

    Deciphering which specific agonist-receptor interactions affect efficacy levels is of high importance, because this will ultimately aid in designing selective drugs. The novel compound NS3861 and cytisine are agonists of nicotinic acetylcholine receptors (nAChRs) and both bind with high affinity...... to heteromeric a3ß4 and a4ß2 nAChRs. However, initial data revealed that the activation patterns of the two compounds show very distinct maximal efficacy readouts at various heteromeric nAChRs. To investigate the molecular determinants behind these observations, we performed in-depth patch clamp...... and a complete lack of activation at a4-containing receptors. The maximal efficacy of NS3861 appeared solely dependent on the nature of the ligand-binding domain, whereas efficacy of cytisine was additionally affected by the nature of the ß-subunit transmembrane domain. Molecular docking to nAChR subtype...

  17. Nicotine poisoning

    Science.gov (United States)

    Nicotine is found in: Chewing tobacco Cigarettes E-cigarettes Liquid nicotine Nicotine gum (Nicorette) Nicotine patches (Habitrol, Nicoderm) Pipe tobacco Some insecticides Tobacco leaves Note: This list may not be all-inclusive.

  18. Association of the nicotinic receptor α7 subunit gene (CHRNA7 with schizophrenia and visual backward masking

    Directory of Open Access Journals (Sweden)

    George eBakanidze

    2013-10-01

    Full Text Available The nicotinic system is involved in the pathophysiology of schizophrenia. However, very little is known about its genetic basis and how it relates to clinical symptoms and potentially pharmacological intervention. Here, we investigated five single nucleotide polymorphisms (SNPs [rs3826029] [rs2337506] [rs982574] [rs904952] [rs2337980] of the cholinergic nicotinic receptor gene, alpha 7 subunit (CHRNA7 and their association to schizophrenia. We found an association with rs904952 (p=0.009 in a German sample of 224 schizophrenic patients and 224 healthy control subjects. The same trend was shown in an independent Georgian sample of 50 schizophrenic patients, 57 first order unaffected relatives, and 51 healthy controls. In addition, visual backward masking (VBM, a sensitive test for early visual information processing, was assessed in the Georgian sample. In line with prior studies, VBM performance deficits were much more pronounced in schizophrenic patients and their unaffected relatives compared to healthy controls (schizophrenic patients: 156 ms; unaffected relatives: 60 ms; healthy controls: 33 ms. VBM was strongly correlated with SNP rs904952 (H[2]=7.3, p=0.026. Our results further support the notion that changes in the nicotinic system are involved in schizophrenia and open the avenue for pharmacological intervention.

  19. Activation and Desensitization of Peripheral Muscle and Neuronal Nicotinic Acetylcholine Receptors by Selected, Naturally-Occurring Pyridine Alkaloids

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    Benedict T. Green

    2016-07-01

    Full Text Available Teratogenic alkaloids can cause developmental defects due to the inhibition of fetal movement that results from desensitization of fetal muscle-type nicotinic acetylcholine receptors (nAChRs. We investigated the ability of two known teratogens, the piperidinyl-pyridine anabasine and its 1,2-dehydropiperidinyl analog anabaseine, to activate and desensitize peripheral nAChRs expressed in TE-671 and SH-SY5Y cells. Activation-concentration response curves for each alkaloid were obtained in the same multi-well plate. To measure rapid desensitization, cells were first exposed to five potentially-desensitizing concentrations of each alkaloid in log10 molar increments from 10 nM to 100 µM and then to a fixed concentration of acetylcholine (ACh, which alone produces near-maximal activation. The fifty percent desensitization concentration (DC50 was calculated from the alkaloid concentration-ACh response curve. Agonist fast desensitization potency was predicted by the agonist potency measured in the initial response. Anabaseine was a more potent desensitizer than anabasine. Relative to anabaseine, nicotine was more potent to autonomic nAChRs, but less potent to the fetal neuromuscular nAChRs. Our experiments have demonstrated that anabaseine is more effective at desensitizing fetal muscle-type nAChRs than anabasine or nicotine and, thus, it is predicted to be more teratogenic.

  20. Methyllycaconitine (MLA) blocks the nicotine evoked anxiogenic effect and 5-HT release in the dorsal hippocampus: possible role of alpha7 receptors.

    Science.gov (United States)

    Tucci, S A; Genn, R F; File, S E

    2003-03-01

    Nicotine has bimodal effects on anxiety, with low doses having an anxiolytic effect and high doses having an anxiogenic effect. The dorsal hippocampus is one of the brain areas that mediate the anxiogenic effect of nicotine through enhanced 5-HT release, but the nAChR subtype(s) that mediate these effects are not known. Intrahippocampal administration of a high dose of nicotine (1 micro g, 4.3 mM) had an anxiogenic effect in the social interaction test that was reversed by co-administration of a behaviourally inactive dose (1.9 ng, 4.3 micro M) of methyllycaconitine (MLA), which is an antagonist at alpha7 and alpha3 nAChR subunits. At a dose (0.8 ng, 4.3 micro ;M) at which its actions would be specific to alpha4beta2 and alpha3beta2 nAChRs dihydro-beta-erythroidine (DHbetaE) was unable to reverse nicotine's anxiogenic effect. Reversal was obtained with a 10-fold higher, but receptor non-specific concentration of DHbetaE (7.8ng, 43 micro M), suggesting that the DHbetaE reversal might have been due to action at alpha7 nAChRs. Exposure of hippocampal slices to MLA (0.25, 05, 1 and 10 micro M) significantly reduced the increase in [(3)H]5-HT release evoked by nicotine (100 micro M). DHbetaE (0.1-0.5 micro M) failed to reverse this effect of nicotine on [(3)H]5-HT release, although higher concentrations (1 and 10 micro M), at which alpha7 subunits would also be affected, were able to do so. Because of the lack of effects of low, receptor specific concentrations of DHbetaE, it is more likely that the MLA reversal of both nicotine's anxiogenic effect and its stimulation of [(3)H]5-HT release is due to action at alpha7 than at alpha3 units. This is perhaps also more likely because the alpha7 receptors are highly expressed in the dorsal hippocampus, whereas the alpha3 subunits are much less abundant. However, what is most important is that, in the dorsal hippocampus, nicotine's anxiogenic effect and induced release of [(3)H]5-HT are mediated by non alpha4beta2 nAChRs, which

  1. A synthetic combinatorial strategy for developing a-conotoxin analogs as potent a7 nicotinic acetylcholine receptor antagonists

    DEFF Research Database (Denmark)

    Armishaw, Christopher J; Singh, Narender; Medina-Franco, Jose L

    2010-01-01

    alpha-Conotoxins are peptide neurotoxins isolated from venomous cone snails that display exquisite selectivity for different subtypes of nicotinic acetylcholine receptors (nAChR). They are valuable research tools that have profound implications in the discovery of new drugs for a myriad of neurop......alpha-Conotoxins are peptide neurotoxins isolated from venomous cone snails that display exquisite selectivity for different subtypes of nicotinic acetylcholine receptors (nAChR). They are valuable research tools that have profound implications in the discovery of new drugs for a myriad......-conotoxin ImI to develop potent and selective alpha(7) nAChR antagonists. A positional scan synthetic combinatorial library was constructed based on the three residues of the n-loop of alpha-conotoxin ImI to give a total of 10,648 possible combinations that were screened for functional activity in an alpha(7......) nAChR Fluo-4/Ca2+ assay, allowing amino acids that confer antagonistic activity for this receptor to be identified. A second series of individual alpha-conotoxin analogs based on the combinations of defined active amino acid residues from positional scan synthetic combinatorial library screening...

  2. Distribution of the a2, a3, and a5 nicotinic acetylcholine receptor subunits in the chick brain

    Directory of Open Access Journals (Sweden)

    Torrão A.S.

    1997-01-01

    Full Text Available Nicotinic acetylcholine receptors (nAChRs are ionotropic receptors comprised of a and ß subunits. These receptors are widely distributed in the central nervous system, and previous studies have revealed specific patterns of localization for some nAChR subunits in the vertebrate brain. In the present study we used immunohistochemical methods and monoclonal antibodies to localize the a2, a3, and a5 nAChR subunits in the chick mesencephalon and diencephalon. We observed a differential distribution of these three subunits in the chick brain, and showed that the somata and neuropil of many central structures contain the a5 nAChR subunit. The a2 and a3 subunits, on the other hand, exhibited a more restricted distribution than a5 and other subunits previously studied, namely a7, a8 and ß2. The patterns of distribution of the different nAChR subunits suggest that neurons in many brain structures may contain several subtypes of nAChRs and that in a few regions one particular subtype may determine the cholinergic nicotinic responses

  3. Central loop of non-conventional toxin WTX from Naja kaouthia is important for interaction with nicotinic acetylcholine receptors.

    Science.gov (United States)

    Lyukmanova, Ekaterina N; Shulepko, Mikhail A; Shenkarev, Zakhar O; Kasheverov, Igor E; Chugunov, Anton O; Kulbatskii, Dmitrii S; Myshkin, Mikhail Yu; Utkin, Yuri N; Efremov, Roman G; Tsetlin, Victor I; Arseniev, Alexander S; Kirpichnikov, Mikhail P; Dolgikh, Dmitry A

    2016-09-01

    'Three-finger' toxin WTX from Naja kaouthia interacts with nicotinic and muscarinic acetylcholine receptors (nAChRs and mAChRs). Mutagenesis and competition experiments with (125)I-α-bungarotoxin revealed that Arg31 and Arg32 residues from the WTX loop II are important for binding to Torpedo californica and human α7 nAChRs. Computer modeling suggested that loop II occupies the orthosteric binding site at α7 nAChR. The similar toxin interface was previously described as a major determinant of allosteric interactions with mAChRs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Mesoionic pyrido[1,2-a]pyrimidinones: A novel class of insecticides inhibiting nicotinic acetylcholine receptors.

    Science.gov (United States)

    Zhang, Wenming; Holyoke, Caleb W; Barry, James; Leighty, Robert M; Cordova, Daniel; Vincent, Daniel R; Hughes, Kenneth A; Tong, My-Hanh T; McCann, Stephen F; Xu, Ming; Briddell, Twyla A; Pahutski, Thomas F; Lahm, George P

    2016-11-15

    A novel class of mesoionic pyrido[1,2-a]pyrimidinones has been discovered with exceptional insecticidal activity controlling a number of insect species, particularly hemiptera and lepidoptera. Mode-of-action studies showed that they act on nicotinic acetylcholine receptors (nAChRs) primarily as inhibitors. Here we report the discovery, evolution, and preparation of this class of chemistry. Our efforts in structure-activity relationship elucidation and biological activity evaluation are also presented. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Decreased Brain Neurokinin-1 Receptor Availability in Chronic Tennis Elbow.

    Directory of Open Access Journals (Sweden)

    Clas Linnman

    Full Text Available Substance P is released in painful and inflammatory conditions, affecting both peripheral processes and the central nervous system neurokinin 1 (NK1 receptor. There is a paucity of data on human brain alterations in NK1 expression, how this system may be affected by treatment, and interactions between central and peripheral tissue alterations. Ten subjects with chronic tennis elbow (lateral epicondylosis were selected out of a larger (n = 120 randomized controlled trial evaluating graded exercise as a treatment for chronic tennis elbow (lateral epicondylosis. These ten subjects were examined by positron emission tomography (PET with the NK1-specific radioligand 11C-GR205171 before, and eight patients were followed up after treatment with graded exercise. Brain binding in the ten patients before treatment, reflecting NK1-receptor availability (NK1-RA, was compared to that of 18 healthy subjects and, longitudinally, to the eight of the original ten patients that agreed to a second PET examination after treatment. Before treatment, patients had significantly lower NK1-RA in the insula, vmPFC, postcentral gyrus, anterior cingulate, caudate, putamen, amygdala and the midbrain but not the thalamus and cerebellum, with the largest difference in the insula contralateral to the injured elbow. No significant correlations between brain NK1-RA and pain, functional severity, or peripheral NK1-RA in the affected limb were observed. In the eight patients examined after treatment, pain ratings decreased in everyone, but there were no significant changes in NK1-RA. These findings indicate a role for the substance P (SP / NK1 receptor system in musculoskeletal pain and tissue healing. As neither clinical parameters nor successful treatment response was reflected in brain NK1-RA after treatment, this may reflect the diverse function of the SP/NK1 system in CNS and peripheral tissue, or a change too small or slow to capture over the three-month treatment.

  6. Sodium nitrate decreases agrin-induced acetylcholine receptor clustering.

    Science.gov (United States)

    Jarosz, Jess; White, Cullen; Grow, Wade A

    2016-05-01

    Humans are exposed to nitrate predominantly through diet with peak plasma concentrations within an hour after ingestion, but additional exposure is obtained from the environment, and minimally through de novo synthesis. Higher nitrate consumption has been associated with methemoglobinemia, spontaneous abortions, atherosclerosis, myocardial ischemia, septic and distressed lung, inflammatory bowel disease, amyotrophic lateral sclerosis, and neural tube defects. However, skeletal muscle development has not been examined. C2C12 skeletal muscle cell cultures were maintained, myoblasts were fused into myotubes, and then cultures were exposed to motor neuron derived agrin to enhance acetylcholine receptor (AChR) clustering. Untreated cultures were compared with cultures exposed to sodium nitrate at concentrations ranging from 10 ng/mL-100 μg/mL. The results reported here demonstrate that 1 μg/mL sodium nitrate was sufficient to decrease the frequency of agrin-induced AChR clustering without affecting myotube formation. In addition, concentrations of sodium nitrate of 1 μg/mL or 100 μg/mL decreased gene expression of the myogenic transcription factor myogenin and AChR in correlation with the agrin-induced AChR clustering data. These results reveal that sodium nitrate decreases the frequency of agrin-induced AChR clustering by a mechanism that includes myogenin and AChR gene expression. As a consequence sodium nitrate may pose a risk for skeletal muscle development and subsequent neuromuscular synapse formation in humans.

  7. Nicotine stimulates urokinase-type plasminogen activator receptor expression and cell invasiveness through mitogen-activated protein kinase and reactive oxygen species signaling in ECV304 endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Khoi, Pham Ngoc; Park, Jung Sun; Kim, Nam Ho; Jung, Young Do, E-mail: ydjung@chonnam.ac.kr

    2012-03-01

    Urokinase-type plasminogen activator receptor (uPAR) expression is elevated during inflammation, tissue remodeling and in many human cancers. This study investigated the effect of nicotine, a major alkaloid in tobacco, on uPAR expression and cell invasiveness in ECV304 endothelial cells. Nicotine stimulated uPAR expression in a dose-dependent manner and activated extracellular signal-regulated kinases-1/2 (Erk-1/2), c-Jun amino-terminal kinase (JNK) and p38 mitogen activated protein kinase (MAPK). Specific inhibitors of MEK-1 (PD98059) and JNK (SP600125) inhibited the nicotine-induced uPAR expression, while the p38 MAPK inhibitor SB203580 did not. Expression vectors encoding dominant negative MEK-1 (pMCL-K97M) and JNK (TAM67) also prevented nicotine-induced uPAR promoter activity. The intracellular hydrogen peroxide (H{sub 2}O{sub 2}) content was increased by nicotine treatment. The antioxidant N-acetylcysteine prevented nicotine-activated production of reactive oxygen species (ROS) and uPAR expression. Furthermore, exogenous H{sub 2}O{sub 2} increased uPAR mRNA expression. Deleted and site-directed mutagenesis demonstrated the involvement of the binding sites of transcription factor nuclear factor-kappaB (NF-κB) and activator protein (AP)-1 in the nicotine-induced uPAR expression. Studies with expression vectors encoding mutated NF-κB signaling molecules and AP-1 decoy confirmed that NF-κB and AP-1 were essential for the nicotine-stimulated uPAR expression. MAPK (Erk-1/2 and JNK) and ROS functioned as upstream signaling molecules in the activation of AP-1 and NF-κB, respectively. In addition, ECV304 endothelial cells treated with nicotine displayed markedly enhanced invasiveness, which was partially abrogated by uPAR neutralizing antibodies. The data indicate that nicotine induces uPAR expression via the MAPK/AP-1 and ROS/NF-κB signaling pathways and, in turn, stimulates invasiveness in human ECV304 endothelial cells. -- Highlights: ► Endothelial cells

  8. Heterogeneous Inhibition in Macroscopic Current Responses of Four Nicotinic Acetylcholine Receptor Subtypes by Cholesterol Enrichment.

    Science.gov (United States)

    Báez-Pagán, Carlos A; Del Hoyo-Rivera, Natalie; Quesada, Orestes; Otero-Cruz, José David; Lasalde-Dominicci, José A

    2016-08-01

    The nicotinic acetylcholine receptor (nAChR), located in the cell membranes of neurons and muscle cells, mediates the transmission of nerve impulses across cholinergic synapses. In addition, the nAChR is also found in the electric organs of electric rays (e.g., the genus Torpedo). Cholesterol, which is a key lipid for maintaining the correct functionality of membrane proteins, has been found to alter the nAChR function. We were thus interested to probe the changes in the functionality of different nAChRs expressed in a model membrane with modified cholesterol to phospholipid ratios (C/P). In this study, we examined the effect of increasing the C/P ratio in Xenopus laevis oocytes expressing the neuronal α7, α4β2, muscle-type, and Torpedo californica nAChRs in their macroscopic current responses. Using the two-electrode voltage clamp technique, it was found that the neuronal α7 and Torpedo nAChRs are significantly more sensitive to small increases in C/P than the muscle-type nAChR. The peak current versus C/P profiles during enrichment display different behaviors; α7 and Torpedo nAChRs display a hyperbolic decay with two clear components, whereas muscle-type and α4β2 nAChRs display simple monophasic decays with different slopes. This study clearly illustrates that a physiologically relevant increase in membrane cholesterol concentration produces a remarkable reduction in the macroscopic current responses of the neuronal α7 and Torpedo nAChRs functionality, whereas the muscle nAChR appears to be the most resistant to cholesterol inhibition among all four nAChR subtypes. Overall, the present study demonstrates differential profiles for cholesterol inhibition among the different types of nAChR to physiological cholesterol increments in the plasmatic membrane. This is the first study to report a cross-correlation analysis of cholesterol sensitivity among different nAChR subtypes in a model membrane.

  9. Nonequivalence of alpha-bungarotoxin binding sites in the native nicotinic receptor molecule

    Energy Technology Data Exchange (ETDEWEB)

    Conti-Tronconi, B.M.; Tang, F.; Walgrave, S.; Gallagher, W. (Univ. of Minnesota, St. Paul (USA))

    1990-01-30

    In the native, membrane-bound form of the nicotinic acetylcholine receptor (M-AcChR) the two sites for the cholinergic antagonist alpha-bungarotoxin (alpha-BGT) have different binding properties. One site has high affinity, and the M-AcChR/alpha-BGT complexes thus formed dissociate very slowly, similar to the complexes formed with detergent-solubilized AcChR (S-AcChR). The second site has much lower affinity (KD approximately 59 +/- 35 nM) and forms quickly reversible complexes. The nondenaturing detergent Triton X-100 is known to solubilize the AcChR in a form unable, upon binding of cholinergic ligands, to open the ion channel and to become desensitized. Solubilization of the AcChR in Triton X-100 affects the binding properties of this second site and converts it to a high-affinity, slowly reversible site. Prolonged incubation of M-AcChR at 4 degrees C converts the low-affinity site to a high-affinity site similar to those observed in the presence of Triton X-100. Although the two sites have similar properties when the AcChR is solubilized in Triton X-100, their nonequivalence can be demonstrated by the effect on alpha-BGT binding of concanavalin A, which strongly reduces the association rate of one site only. The Bmax of alpha-BGT to either Triton-solubilized AcChR or M-AcChR is not affected by the presence of concanavalin A. Occupancy of the high-affinity, slowly reversible site in M-AcChR inhibits the Triton X-100 induced conversion to irreversibility of the second site. At difference with alpha-BGT, the long alpha-neurotoxin from Naja naja siamensis venom (alpha-NTX) binds with high affinity and in a very slowly reversible fashion to two sites in the M-AcChR. We confirm here that Triton-solubilized AcChR or M-AcChR binds in a very slowly reversible fashion the same amount of alpha-NTX.

  10. Inhibition of Gata4 and Tbx5 by Nicotine-Mediated DNA Methylation in Myocardial Differentiation

    Directory of Open Access Journals (Sweden)

    Xue-Yan Jiang

    2017-02-01

    Full Text Available Maternal nicotine exposure causes alteration of gene expression and cardiovascular programming. The discovery of nicotine-medicated regulation in cardiogenesis is of major importance for the study of cardiac defects. The present study investigated the effect of nicotine on cardiac gene expression and epigenetic regulation during myocardial differentiation. Persistent nicotine exposure selectively inhibited expression of two cardiac genes, Tbx5 and Gata4, by promoter DNA hypermethylation. The nicotine-induced suppression on cardiac differentiation was restored by general nicotinic acetylcholine receptor inhibition. Consistent results of Tbx5 and Gata4 gene suppression and cardiac function impairment with decreased left ventricular ejection fraction were obtained from in vivo studies in offspring. Our results present a direct repressive effect of nicotine on myocardial differentiation by regulating cardiac gene suppression via promoter DNA hypermethylation, contributing to the etiology of smoking-associated cardiac defects.

  11. Cigarette smoking during pregnancy regulates the expression of specific nicotinic acetylcholine receptor (nAChR) subunits in the human placenta

    Energy Technology Data Exchange (ETDEWEB)

    Machaalani, R., E-mail: rita.machaalani@sydney.edu.au [Department of Medicine, The University of Sydney, NSW 2006 (Australia); Bosch Institute, The University of Sydney, NSW 2006 (Australia); The Children' s Hospital at Westmead, NSW 2145 (Australia); Ghazavi, E. [Bosch Institute, The University of Sydney, NSW 2006 (Australia); School of Medical Sciences (Pharmacology), The University of Sydney, NSW 2006 (Australia); Hinton, T. [School of Medical Sciences (Pharmacology), The University of Sydney, NSW 2006 (Australia); Waters, K.A. [Department of Medicine, The University of Sydney, NSW 2006 (Australia); The Children' s Hospital at Westmead, NSW 2145 (Australia); Hennessy, A. [School of Medicine, University of Western Sydney, NSW 2751 (Australia); Heart Research Institute, 7 Eliza St Newtown, NSW 2042 (Australia)

    2014-05-01

    Smoking during pregnancy is associated with low birth weight, premature delivery, and neonatal morbidity and mortality. Nicotine, a major pathogenic compound of cigarette smoke, binds to the nicotinic acetylcholine receptors (nAChRs). A total of 16 nAChR subunits have been identified in mammals (9 α, 4 β, and 1 δ, γ and ε subunits). The effect of cigarette smoking on the expression of these subunits in the placenta has not yet been determined, thus constituting the aim of this study. Using RT-qPCR and western blotting, this study investigated all 16 mammalian nAChR subunits in the normal healthy human placenta, and compared mRNA and protein expressions in the placentas from smokers (n = 8) to controls (n = 8). Our data show that all 16 subunit mRNAs are expressed in the normal, non-diseased human placenta and that the expression of α2, α3, α4, α9, β2 and β4 subunits is greater than the other subunits. For mRNA, cigarette smoke exposure was associated with increased expression of the α9 subunit, and decreased expression of the δ subunit. At the protein level, expression of both α9 and δ was increased. Thus, cigarette smoking in pregnancy is sufficient to regulate nAChR subunits in the placenta, specifically α9 and δ subunits, and could contribute to the adverse effects of vasoconstriction and decreased re-epithelialisation (α9), and increased calcification and apoptosis (δ), seen in the placentas of smoking women. - Highlights: • All 16 mammalian nAChR subunits are expressed in the human placenta. • Cigarette smoking increases α9 mRNA and protein in the placenta. • Cigarette smoking decreases δ mRNA but increases δ protein in the placenta.

  12. Förster Resonance Energy Transfer (FRET) Correlates of Altered Subunit Stoichiometry in Cys-Loop Receptors, Exemplified by Nicotinic α4β2

    Science.gov (United States)

    Srinivasan, Rahul; Richards, Christopher I.; Dilworth, Crystal; Moss, Fraser J.; Dougherty, Dennis A.; Lester, Henry A.

    2012-01-01

    We provide a theory for employing Förster resonance energy transfer (FRET) measurements to determine altered heteropentameric ion channel stoichiometries in intracellular compartments of living cells. We simulate FRET within nicotinic receptors (nAChRs) whose α4 and β2 subunits contain acceptor and donor fluorescent protein moieties, respectively, within the cytoplasmic loops. We predict FRET and normalized FRET (NFRET) for the two predominant stoichiometries, (α4)3(β2)2 vs. (α4)2(β2)3. Studying the ratio between FRET or NFRET for the two stoichiometries, minimizes distortions due to various photophysical uncertainties. Within a range of assumptions concerning the distance between fluorophores, deviations from plane pentameric geometry, and other asymmetries, the predicted FRET and NFRET for (α4)3(β2)2 exceeds that of (α4)2(β2)3. The simulations account for published data on transfected Neuro2a cells in which α4β2 stoichiometries were manipulated by varying fluorescent subunit cDNA ratios: NFRET decreased monotonically from (α4)3(β2)2 stoichiometry to mostly (α4)2(β2)3. The simulations also account for previous macroscopic and single-channel observations that pharmacological chaperoning by nicotine and cytisine increase the (α4)2(β2)3 and (α4)3(β2)2 populations, respectively. We also analyze sources of variability. NFRET-based monitoring of changes in subunit stoichiometry can contribute usefully to studies on Cys-loop receptors. PMID:22949846

  13. The α7-nACh nicotinic receptor and its role in memory and selected diseases of the central nervous system

    Directory of Open Access Journals (Sweden)

    Urszula Baranowska

    2017-07-01

    Full Text Available α7-nACh is one of the major nicotinic cholinergic receptor subtypes found in the brain. It is broadly expressed in the hippocampal and cortical neurons, the regions which play a key role in memory formation. Although α7-nACh receptors may serve as postsynaptic receptors mediating classical neurotransmission, they usually function as presynaptic modulators responsible for the release of other neurotransmitters, such as glutamate, γ-aminobutyric acid, dopamine, and norepinephrine. They can, therefore, affect a wide array of neurobiological functions. In recent years, research has found that a large number of agonists and positive allosteric modulators of α7-nAChR induce beneficial effects on learning and memory. Consistently, mice deficient in chrna7 (the gene encoding α7-nAChR protein, are characterized by memory deficits. In addition, decreased expression and function of α7-nAChR is associated agoniwith many neurological diseases including schizophrenia, bipolar disorder, learning disability, attention deficit hyperactivity disorder, Alzheimer disease, autism, and epilepsy. In the recent years many animal experiments and clinical trials using α7-nAChR ligands were conducted. The results of these studies strongly indicate that agonists and positive allosteric modulators of α7-nAChR are promising therapeutic agents for diseases associated with cognitive deficits.

  14. Nicotine induces mitochondrial fission through mitofusin degradation in human multipotent embryonic carcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Naoya; Yamada, Shigeru [Division of Pharmacology, National Institute of Health Sciences (Japan); Asanagi, Miki [Division of Pharmacology, National Institute of Health Sciences (Japan); Faculty of Engineering, Department of Materials Science and Engineering, Yokohama National University (Japan); Sekino, Yuko [Division of Pharmacology, National Institute of Health Sciences (Japan); Kanda, Yasunari, E-mail: kanda@nihs.go.jp [Division of Pharmacology, National Institute of Health Sciences (Japan)

    2016-02-05

    Nicotine is considered to contribute to the health risks associated with cigarette smoking. Nicotine exerts its cellular functions by acting on nicotinic acetylcholine receptors (nAChRs), and adversely affects normal embryonic development. However, nicotine toxicity has not been elucidated in human embryonic stage. In the present study, we examined the cytotoxic effects of nicotine in human multipotent embryonal carcinoma cell line NT2/D1. We found that exposure to 10 μM nicotine decreased intracellular ATP levels and inhibited proliferation of NT2/D1 cells. Because nicotine suppressed energy production, which is a critical mitochondrial function, we further assessed the effects of nicotine on mitochondrial dynamics. Staining with MitoTracker revealed that 10 μM nicotine induced mitochondrial fragmentation. The levels of the mitochondrial fusion proteins, mitofusins 1 and 2, were also reduced in cells exposed to nicotine. These nicotine effects were blocked by treatment with mecamylamine, a nonselective nAChR antagonist. These data suggest that nicotine degrades mitofusin in NT2/D1 cells and thus induces mitochondrial dysfunction and cell growth inhibition in a nAChR-dependent manner. Thus, mitochondrial function in embryonic cells could be used to assess the developmental toxicity of chemicals.

  15. Intravenous nicotine self-administration and cue-induced reinstatement in mice: Effects of nicotine dose, rate of drug infusion and prior instrumental training

    Science.gov (United States)

    Fowler, Christie D.; Kenny, Paul J.

    2011-01-01

    Intravenous nicotine self-administration is the most direct measure of nicotine reinforcement in laboratory animals, but this procedure has proven difficult to establish in mice. We found that stable responding for nicotine in C57BL6/J mice was facilitated by prior instrumental training for food reward, initial exposure of mice to a lower unit dose of nicotine (0.03 mg/kg/infusion) before access to higher doses, a slower rate of drug delivery (3-sec versus 1-sec infusion), consistency in schedule of daily testing, and low extraneous noise during testing. Under these conditions, we found that mice lever-pressing for nicotine (0.03–0.4 mg/kg/infusion; 60-min test sessions) under a fixed-ratio 5 time-out 20-sec (FR5TO20) reinforcement schedule consumed the drug according to an inverted ‘U’-shaped dose-response curve. Mice switched their responding onto a previously non-reinforced lever to continue earning nicotine infusions when the active/inactive lever assignment was reversed. The nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine decreased responding for nicotine, but not food rewards, verifying that nAChRs regulate nicotine self-administration in mice. The cue-light paired with nicotine delivery did not support responding when delivered independently of nicotine infusions, further verifying that mice responded selectivity for the drug. Nicotine-seeking responses extinguished when nicotine infusions and the cue-light were withheld, and exposure to the cue-light reinstated responding. Finally, mice without prior instrumental food training acquired stable responding for nicotine under the FR5TO20 schedule, but required a greater number of sessions. These data demonstrate that nicotine is an effective reinforcer in mice and establish conditions under which the drug is reliably self-administered by mice. PMID:21640128

  16. Partial agonism at the α7 nicotinic acetylcholine receptor improves attention, impulsive action and vigilance in low attentive rats.

    Science.gov (United States)

    Hayward, Andrew; Adamson, Lisa; Neill, Joanna C

    2017-04-01

    Inattention is a disabling symptom in conditions such as schizophrenia and attention deficit/hyperactivity disorder. Nicotine can improve attention and vigilance, but is unsuitable for clinical use due to abuse liability. Genetic knockout of the α7 nicotinic acetylcholine receptor (nAChR) induces attention deficits therefore selective agonism may improve attention, without the abuse liability associated with nicotine. The α7 nAChR partial agonist encenicline (formerly EVP-6124) enhances memory in rodents and humans. Here we investigate, for the first time, efficacy of encenicline to improve attention and vigilance in animals behaviourally grouped for low attentive traits in the 5 choice-continuous performance task (5C-CPT). Female Lister Hooded rats were trained to perform the 5C-CPT with a variable stimulus duration (SD). Animals were then grouped based on performance into upper and lower quartiles of d' (vigilance) and accuracy (selective attention), producing high-attentive (HA) and low-attentive (LA) groups. LA animals showed an increase in selective attention and vigilance at 0.3mg/kg encenicline, a reduction in impulsive action (probability of false alarms) and increase in vigilance following 1mg/kg at 0.75sSD. At 1mg/kg, HA animals had reduced selective attention at 0.75sSD and reduced vigilance at 0.75 and 1.25sSD. Improvement of attention, vigilance and impulsive action in LA animals demonstrates that encenicline has pro-attentive properties dependent on baseline levels of performance. Our work suggests that α7 nAChR partial agonism may improve attention particularly in conditions with low attention. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

  17. Alpha-conotoxin analogs with additional positive charge show increased selectivity towards Torpedo californica and some neuronal subtypes of nicotinic acetylcholine receptors

    NARCIS (Netherlands)

    Kasheverov, I.E.; Zhmak, M.N.; Vulfius, C.A.; Corbacheva, E.V.; Mordvintsev, D.Y.; Utkin, Y.N.; van Elk, R.; Smit, A.B.; Tsetlin, V.I.

    2006-01-01

    α-Conotoxins from Conus snails are indispensable tools for distinguishing various subtypes of nicotinic acetylcholine receptors (nAChRs), and synthesis of α-conotoxin analogs may yield novel antagonists of higher potency and selectivity. We incorporated additional positive charges into α-conotoxins

  18. Radiosynthesis and in vitro validation of 3H-NS14492 as a novel high affinity alpha7 nicotinic receptor radioligand

    DEFF Research Database (Denmark)

    Magnussen, Janus H.; Ettrup, Anders; Donat, Cornelius K.

    2015-01-01

    emission tomography (PET) occupancy studies of the alpha 7 nicotinic receptor in the pig brain. In order to investigate the utility of the same compound for in vitro studies, 3H-NS14492 was synthesized and its binding properties were characterized using in vitro autoradiography and homogenate binding...

  19. Binding of imidacloprid, thiamethoxam and N-desmethylthiamethoxam to nicotinic receptors of Myzus persicae: pharmacological profiling using neonicotinoids, natural agonists and antagonists.

    Science.gov (United States)

    Kayser, Hartmut; Lehmann, Katrin; Gomes, Marilyne; Schleicher, Wolfgang; Dotzauer, Karin; Moron, Margarethe; Maienfisch, Peter

    2016-11-01

    The increasing structural diversity of the neonicotinoid class of insecticides presently used in crop protection calls for a more detailed analysis of their mode of action at their cellular targets, the nicotinic acetylcholine receptors. Comparative radioligand binding studies using membranes of Myzus persicae (Sulzer) and representatives of the chloropyridyl subclass (imidacloprid), the chlorothiazolyl subclass (thiamethoxam), the tetrahydrofuranyl subclass (dinotefuran), as well as the novel sulfoximine type (sulfoxaflor), which is not a neonicotinoid, reveal significant differences in the number of binding sites, the displacing potencies and the mode of binding interference. Furthermore, the mode of interaction of [ 3 H]thiamethoxam and the nicotinic antagonists methyllycaconitine and dihydro-β-erythroidine is unique, with Hill values of >1, clearly different to the values of around unity for [ 3 H]imidacloprid and [ 3 H]N-desmethylthiamethoxam. The interaction of [ 3 H]N-desmethylthiamethoxam with the agonist (-)nicotine is also characterised by a Hill value of >1. There is no single conserved site or mode of binding of neonicotinoids and related nicotinic ligands to their target receptor, but a variety of binding pockets depending on the combination of receptor subunits, the receptor subtype, its functional state, as well as the structural flexibility of both the binding pockets and the ligands. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. 11C-NS14492 as a novel PET radioligand for imaging cerebral alpha7 nicotinic acetylcholine receptors: in vivo evaluation and drug occupancy measurements

    DEFF Research Database (Denmark)

    Ettrup, Anders; Mikkelsen, Jens D; Lehel, Szabolcs

    2011-01-01

    Small-molecule a(7) nicotinic acetylcholine receptor (a(7)nAChR) agonists are currently validated for use as treatment for cognitive disturbances in schizophrenia and in Alzheimer disease. A suitable radiolabeled a(7)nAChR PET tracer would be important for in vivo quantification of a(7)n...

  1. 11C-NS14492 as a novel PET radioligand for imaging cerebral alpha7 nicotinic acetylcholine receptors: in vivo evaluation and drug occupancy measurements

    DEFF Research Database (Denmark)

    Ettrup, Anders; Mikkelsen, Jens D; Lehel, Szabolcs

    2011-01-01

    Small-molecule α(7) nicotinic acetylcholine receptor (α(7)nAChR) agonists are currently validated for use as treatment for cognitive disturbances in schizophrenia and in Alzheimer disease. A suitable radiolabeled α(7)nAChR PET tracer would be important for in vivo quantification of α(7)n...

  2. Engineered α4β2 nicotinic acetylcholine receptors as models for measuring agonist binding and effect at the orthosteric low-affinity α4-α4 interface

    DEFF Research Database (Denmark)

    Ahring, Philip K.; Olsen, Jeppe A.; Nielsen, Elsebet O.

    2015-01-01

    The nicotinic acetylcholine receptor alpha 4 beta 2 is important for normal mammalian brain function and is known to express in two different stoichiometries, (alpha 4)(2)(beta 2)(3) and (alpha 4)(3)(beta 2)(2). While these are similar in many aspects, the (alpha 4)(3)(beta 2)(2) stoichiometry...

  3. Purification of the nicotinic acetylcholine receptor protein by affinity chromatography using a regioselectively modified and reversibly immobilized alpha-toxin from Naja nigricollis

    NARCIS (Netherlands)

    Ringler, P; Kessler, P; Menez, A; Brisson, A

    1997-01-01

    A new method of affinity chromatography purification of the detergent-solubilized nicotinic acetylcholine receptor protein (nAChR) is presented, based on the reversible coupling of a chemically monomodified alpha-toxin from Naja nigricollis to a resin. The alpha-toxin was monothiolated on the

  4. The non-competitive acetylcholinesterase inhibitor APS12-2 is a potent antagonist of skeletal muscle nicotinic acetylcholine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Grandič, Marjana [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia); Aráoz, Romulo; Molgó, Jordi [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Turk, Tom; Sepčić, Kristina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana (Slovenia); Benoit, Evelyne [CNRS, Institut de Neurobiologie Alfred Fessard, FRC 2118, Laboratoire de Neurobiologie et Développement, UPR 3294, F-91198 Gif-sur-Yvette Cedex (France); Frangež, Robert, E-mail: robert.frangez@vf.uni-lj.si [Institute of Physiology, Pharmacology and Toxicology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana (Slovenia)

    2012-12-01

    APS12-2, a non-competitive acetylcholinesterase inhibitor, is one of the synthetic analogs of polymeric alkylpyridinium salts (poly-APS) isolated from the marine sponge Reniera sarai. In the present work the effects of APS12-2 were studied on isolated mouse phrenic nerve–hemidiaphragm muscle preparations, using twitch tension measurements and electrophysiological recordings. APS12-2 in a concentration-dependent manner blocked nerve-evoked isometric muscle contraction (IC{sub 50} = 0.74 μM), without affecting directly-elicited twitch tension up to 2.72 μM. The compound (0.007–3.40 μM) decreased the amplitude of miniature endplate potentials until a complete block by concentrations higher than 0.68 μM, without affecting their frequency. Full size endplate potentials, recorded after blocking voltage-gated muscle sodium channels, were inhibited by APS12-2 in a concentration-dependent manner (IC{sub 50} = 0.36 μM) without significant change in the resting membrane potential of the muscle fibers up to 3.40 μM. The compound also blocked acetylcholine-evoked inward currents in Xenopus oocytes in which Torpedo (α1{sub 2}β1γδ) muscle-type nicotinic acetylcholine receptors (nAChRs) have been incorporated (IC{sub 50} = 0.0005 μM), indicating a higher affinity of the compound for Torpedo (α1{sub 2}β1γδ) than for the mouse (α1{sub 2}β1γε) nAChR. Our data show for the first time that APS12-2 blocks neuromuscular transmission by a non-depolarizing mechanism through an action on postsynaptic nAChRs of the skeletal neuromuscular junction. -- Highlights: ► APS12-2 produces concentration-dependent inhibition of nerve-evoked muscle contraction in vitro. ► APS12-2 blocks MEPPs and EPPs at the neuromuscular junction. APS12-2 blocks ACh-activated current in Xenopus oocytes incorporated with Torpedo nAChRs.

  5. Assessment of {alpha}7 nicotinic acetylcholine receptor availability in juvenile pig brain with [{sup 18}F]NS10743

    Energy Technology Data Exchange (ETDEWEB)

    Deuther-Conrad, Winnie; Fischer, Steffen; Hiller, Achim; Funke, Uta; Brust, Peter [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmacy, Leipzig (Germany); Becker, Georg; Sabri, Osama [Univ. of Leipzig, Dept. of Nuclear Medicine, Leipzig (Germany); Cumming, Paul; Xiong, Guoming [Univ. of Munich, Dept. of Nuclear Medicine, Munich (Germany); Peters, Dan [NeuroSearch A/S, Ballerup (Denmark)

    2011-08-15

    To conduct a quantitative PET assessment of the specific binding sites in the brain of juvenile pigs for [{sup 18}F]NS10743, a novel diazabicyclononane derivative targeting {alpha}7 nicotinic acetylcholine receptors ({alpha}7 nAChRs). Dynamic PET recordings were made in isoflurane-anaesthetized juvenile pigs during 120 min after administration of [{sup 18}F]NS10743 under baseline conditions (n = 3) and after blocking of the {alpha}7 nAChR with NS6740 (3 mg.kg{sup -1} bolus + 1 mg.kg{sup -1}.h{sup -1} continuous infusion; n = 3). Arterial plasma samples were collected for determining the input function of the unmetabolized tracer. Kinetic analysis of regional brain time-radioactivity curves was performed, and parametric maps were calculated relative to arterial input. Plasma [{sup 18}F]NS10743 passed readily into the brain, with peak uptake occurring in {alpha}7 nAChR-expressing brain regions such as the colliculi, thalamus, temporal lobe and hippocampus. The highest SUV{sub max} was approximately 2.3, whereas the lowest uptake was in the olfactory bulb (SUV{sub max} 1.53 {+-} 0.32). Administration of NS6740 significantly decreased [{sup 18}F]NS10743 binding late in the emission recording throughout the brain, except in the olfactory bulb, which was therefore chosen as reference region for calculation of BP{sub ND}. The baseline BP{sub ND} ranged from 0.39 {+-} 0.08 in the cerebellum to 0.76 {+-} 0.07 in the temporal lobe. Pretreatment and constant infusion with NS6740 significantly reduced the BP{sub ND} in regions with high [{sup 18}F]NS10743 binding (temporal lobe -29%, p = 0.01; midbrain: -35%, p = 0.02), without significantly altering the BP{sub ND} in low binding regions (cerebellum: -16%, p = 0.2). This study confirms the potential of [{sup 18}F]NS10743 as a target-specific radiotracer for the molecular imaging of central {alpha}7 nAChRs by PET. (orig.)

  6. Alpha-7 Nicotinic Receptor Signaling Pathway Participates in the Neurogenesis Induced by ChAT-Positive Neurons in the Subventricular Zone.

    Science.gov (United States)

    Wang, Jianping; Lu, Zhengfang; Fu, Xiaojie; Zhang, Di; Yu, Lie; Li, Nan; Gao, Yufeng; Liu, Xianliang; Yin, Chunmao; Ke, Junji; Li, Liyuan; Zhai, Mengmeng; Wu, Shiwen; Fan, Jiahong; Lv, Liang; Liu, Junchao; Chen, Xuemei; Yang, Qingwu; Wang, Jian

    2017-05-27

    Choline acetyltransferase-positive (ChAT + ) neurons within the subventricular zone (SVZ) have been shown to promote neurogenesis after stroke in mice by secreting acetylcholine (ACh); however, the mechanisms remain unclear. Receptors known to bind ACh include the nicotinic ACh receptors (nAChRs), which are present in the SVZ and have been shown to be important for cell proliferation, differentiation, and survival. In this study, we investigated the neurogenic role of the alpha-7 nAChR (α7 nAChR) in a mouse model of middle cerebral artery occlusion (MCAO) by using α7 nAChR inhibitor methyllycaconitine. Mice subjected to MCAO exhibited elevated expression of cytomembrane and nuclear fibroblast growth factor receptor 1 (FGFR1), as well as increased expression of PI3K, pAkt, doublecortin (DCX), polysialylated - neuronal cell adhesion molecule (PSA-NCAM), and mammalian achaete-scute homolog 1 (Mash1). MCAO mice also had more glial fibrillary acidic protein (GFAP)/5-bromo-2'-deoxyuridine (BrdU)-positive cells and DCX-positive cells in the SVZ than did the sham-operated group. Methyllycaconitine treatment increased cytomembrane FGFR1 expression and GFAP/BrdU-positive cells, upregulated the levels of phosphoinositide 3-kinase (PI3K) and phospho-Akt (pAkt), decreased nuclear FGFR1 expression, decreased the number of DCX-positive cells, and reduced the levels of DCX, PSA-NCAM, and Mash1 in the SVZ of MCAO mice compared with levels in vehicle-treated MCAO mice. MCAO mice treated with α7 nAChR agonist PNU-282987 exhibited the opposite effects. Our data show that α7 nAChR may decrease the proliferation of neural stem cells and promote differentiation of existing neural stem cells after stroke. These results identify a new mechanism of SVZ ChAT + neuron-induced neurogenesis.

  7. Minimal RNA aptamer sequences that can inhibit or alleviate noncompetitive inhibition of the muscle-type nicotinic acetylcholine receptor.

    Science.gov (United States)

    Sivaprakasam, Kannan; Pagán, Oné R; Hess, George P

    2010-02-01

    Combinatorially synthesized nucleotide polymers have been used during the last decade to find ligands that bind to specific sites on biological molecules, including membrane-bound proteins such as the nicotinic acetylcholine receptors (nAChRs). The neurotransmitter receptors belong to a group of four structurally related proteins that regulate signal transmission between ~10(11) neurons of the mammalian nervous system. The nAChRs are inhibited by compounds such as the anticonvulsant MK-801 [(+)-dizocilpine] and abused drugs such as cocaine. Based on predictions arising from the mechanism of receptor inhibition by MK-801 and cocaine, we developed two classes of RNA aptamers: class I members, which inhibit the nAChR, and class II members, which alleviate inhibition of the receptor by MK-801 and cocaine. The systematic evolution of ligands by the exponential enrichment (SELEX) method was used to obtain these compounds. Here, we report that we have truncated RNA aptamers in each class to determine the minimal nucleic acid sequence that retains the characteristic function for which the aptamer was originally selected. We demonstrate that a truncated class I aptamer containing a sequence of seven nucleotides inhibits the nAChR and that a truncated class II aptamer containing a sequence of only four nucleotides can alleviate MK-801 inhibition.

  8. Nicotine Gum

    Science.gov (United States)

    Nicotine chewing gum is used to help people stop smoking cigarettes. Nicotine chewing gum should be used together with a ... support groups, counseling, or specific behavioral change techniques. Nicotine gum is in a class of medications called ...

  9. GLUCOSE ATTENUATES IMPAIRMENTS IN MEMORY AND CREB ACTIVATION PRODUCED BY AN α4β2 BUT NOT AN α7 NICOTINIC RECEPTOR ANTAGONIST

    OpenAIRE

    Morris, Ken A.; Li, Sisi; Bui, Duat D.; Gold, Paul E.

    2012-01-01

    Glucose improves memory for a variety of tasks when administered to rats and mice near the time of training. Prior work indicates glucose may enhance memory by increasing the synthesis and release of the neurotransmitter acetylcholine in the brain. To investigate if specific acetylcholine receptor subtypes may mediate some of the memory-enhancing actions of glucose, we examined the effects of subtype-specific nicotinic acetylcholine receptor antagonists on memory in Fischer-344 rats and also ...

  10. (S-5-ethynyl-anabasine, a novel compound, is a more potent agonist than other nicotine alkaloids on the nematode Asu-ACR-16 receptor

    Directory of Open Access Journals (Sweden)

    Fudan Zheng

    2017-04-01

    Here, we describe the synthesis of a novel agonist, (S-5-ethynyl-anabasine, and show that it is more potent (EC50 0.14 ± 0.01 μM than other nicotine alkaloids on Asu-ACR-16. Agonists acting on ACR-16 receptors have the potential to circumvent drug resistance to anthelmintics, like levamisole, that do not act on the ACR-16 receptors.

  11. Effect of α{sub 7} nicotinic acetylcholine receptor agonists and antagonists on motor function in mice

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Kevin D., E-mail: kevin.welch@ars.usda.gov [USDA/ARS Poisonous Plant Research Laboratory, 1150 E. 1400N., Logan, UT 84341 (United States); Pfister, James A. [USDA/ARS Poisonous Plant Research Laboratory, 1150 E. 1400N., Logan, UT 84341 (United States); Lima, Flavia G. [Federal University of Goías, School of Veterinary Medicine, Goiânia, Goías (Brazil); Green, Benedict T.; Gardner, Dale R. [USDA/ARS Poisonous Plant Research Laboratory, 1150 E. 1400N., Logan, UT 84341 (United States)

    2013-02-01

    Nicotinic acetylcholine receptors (nAChRs) are ligand-gated cation channels found throughout the body, and serve to mediate diverse physiological functions. Muscle-type nAChRs located in the motor endplate region of muscle fibers play an integral role in muscle contraction and thus motor function. The toxicity and teratogenicity of many plants (which results in millions of dollars in losses annually to the livestock industry) are due to various toxins that bind to nAChRs including deltaline and methyllycaconitine (MLA) from larkspur (Delphinium) species, and nicotine and anabasine from tobacco (Nicotiana) species. The primary result of the actions of these alkaloids at nAChRs is neuromuscular paralysis and respiratory failure. The objective of this study was to further characterize the motor coordination deficiencies that occur upon exposure to a non-lethal dose of nAChR antagonists MLA and deltaline as well as nAChR agonists nicotine and anabasine. We evaluated the effect of nAChR agonists and antagonists on the motor function and coordination in mice using a balance beam, grip strength meter, rotarod, open field analysis and tremor monitor. These analyses demonstrated that within seconds after treatment the mice had significant loss of motor function and coordination that lasted up to 1 min, followed by a short period of quiescence. Recovery to normal muscle coordination was rapid, typically within approximately 10 min post-dosing. However, mice treated with the nAChR agonist nicotine and anabasine required a slightly longer time to recover some aspects of normal muscle function in comparison to mice treated with the nAChR antagonist MLA or deltaline. -- Highlights: ► Mice treated with nAChR agonists and antagonists have a loss in motor function. ► These deficits are temporary as near normal motor function returns within 10 min. ► There are compound-specific differences in the effects on motor function.

  12. Nicotine Component of Cigarette Smoke Extract (CSE) Decreases the Cytotoxicity of CSE in BEAS-2B Cells Stably Expressing Human Cytochrome P450 2A13.

    Science.gov (United States)

    Ji, Minghui; Zhang, Yudong; Li, Na; Wang, Chao; Xia, Rong; Zhang, Zhan; Wang, Shou-Lin

    2017-10-13

    Cytochrome P450 2A13 (CYP2A13), an extrahepatic enzyme mainly expressed in the human respiratory system, has been reported to mediate the metabolism and toxicity of cigarette smoke. We previously found that nicotine inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism by CYP2A13, but its influence on other components of cigarette smoke remains unclear. The nicotine component of cigarette smoke extract (CSE) was separated, purified, and identified using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), splitting CSE into a nicotine section (CSE-N) and nicotine-free section (CSE-O). Cell viability and apoptosis by Cell Counting Kit-8 (CCK-8) and flow cytometry assays were conducted on immortalized human bronchial epithelial (BEAS-2B) cells stably expressing CYP2A13 (B-2A13) or vector (B-V), respectively. Interestingly, CSE and CSE-O were toxic to BEAS-2B cells whereas CSE-N showed less cytotoxicity. CSE-O was more toxic to B-2A13 cells than to B-V cells (IC 50 of 2.49% vs. 7.06%), which was flatted by 8-methoxypsoralen (8-MOP), a CYP inhibitor. CSE-O rather than CSE or CSE-N increased apoptosis of B-2A13 cells rather than B-V cells. Accordingly, compared to CSE-N and CSE, CSE-O significantly changed the expression of three pairs of pro- and anti-apoptotic proteins, Bcl-2 Associated X Protein/B cell lymphoma-2 (Bax/Bcl-2), Cleaved Poly (Adenosine Diphosphate-Ribose) Polymerase/Poly (Adenosine Diphosphate-Ribose) Polymerase (C-PARP/PARP), and C-caspase-3/caspase-3, in B-2A13 cells. In addition, recombination of CSE-N and CSE-O (CSE-O/N) showed similar cytotoxicity and apoptosis to the original CSE. These results demonstrate that the nicotine component decreases the metabolic activation of CYP2A13 to CSE and aids in understanding the critical role of CYP2A13 in human respiratory diseases caused by cigarette smoking.

  13. Effects of nicotine on homeostatic and hedonic components of food intake.

    Science.gov (United States)

    Stojakovic, Andrea; Espinosa, Enma P; Farhad, Osman T; Lutfy, Kabirullah

    2017-10-01

    Chronic tobacco use leads to nicotine addiction that is characterized by exaggerated urges to use the drug despite the accompanying negative health and socioeconomic burdens. Interestingly, nicotine users are found to be leaner than the general population. Review of the existing literature revealed that nicotine affects energy homeostasis and food consumption via altering the activity of neurons containing orexigenic and anorexigenic peptides in the brain. Hypothalamus is one of the critical brain areas that regulates energy balance via the action of these neuropeptides. The equilibrium between these two groups of peptides can be shifted by nicotine leading to decreased food intake and weight loss. The aim of this article is to review the existing literature on the effect of nicotine on food intake and energy homeostasis and report on the changes that nicotine brings about in the level of these peptides and their receptors that may explain changes in food intake and body weight induced by nicotine. Furthermore, we review the effect of nicotine on the hedonic aspect of food intake. Finally, we discuss the involvement of different subtypes of nicotinic acetylcholine receptors in the regulatory action of nicotine on food intake and energy homeostasis. © 2017 Society for Endocrinology.

  14. Minimal Effects of Age and Exposure to a Noisy Environment on Hearing in Alpha9 Nicotinic Receptor Knockout Mice

    Directory of Open Access Journals (Sweden)

    Amanda M. Lauer

    2017-06-01

    Full Text Available Studies have suggested a role of weakened medial olivocochlear (OC efferent feedback in accelerated hearing loss and increased susceptibility to noise. The present study investigated the progression of hearing loss with age and exposure to a noisy environment in medial OC-deficient mice. Alpha9 nicotinic acetylcholine receptor knockout (α9KO and wild types were screened for hearing loss using auditory brainstem responses. α9KO mice housed in a quiet environment did not show increased hearing loss compared to wild types in young adulthood and middle age. Challenging the medial OC system by housing in a noisy environment did not increase hearing loss in α9KO mice compared to wild types. ABR wave 1 amplitudes also did not show differences between α9KO mice and wild types. These data suggest that deficient medial OC feedback does not result in early onset of hearing loss.

  15. Nicotinic Acid Receptor GPR109A Is Down-Regulated in Human Macrophage-Derived Foam Cells

    Science.gov (United States)

    Chai, Joshua T.; Digby, Janet E.; Ruparelia, Neil; Jefferson, Andrew; Handa, Ashok; Choudhury, Robin P.

    2013-01-01

    Nicotinic acid (NA) regresses atherosclerosis in human imaging studies and reduces atherosclerosis in mice, mediated by myeloid cells, independent of lipoproteins. Since GPR109A is expressed by human monocytes, we hypothesized that NA may drive cholesterol efflux from foam cells. In THP-1 cells NA suppressed LPS-induced mRNA transcription of MCP-1 by 76.6±12.2% (Pfoam cells by 37.7±3.1% (Pfoam cells on either cholesterol efflux or key RCT genes transcription. Upon foam cell induction, NA lost its effect on PPARγ and cAMP pathways, since its receptor, GPR109A, was down-regulated by foam cell transformation. This observation was confirmed in explanted human carotid plaques. In conclusion, despite NA’s anti-inflammatory effect on human macrophages, it has no effect on foam cells in reverse cholesterol transport; due to GPR109A down-regulation. PMID:23658787

  16. The selective alpha7 nicotinic acetylcholine receptor agonist A-582941 activates immediate early genes in limbic regions of the forebrain

    DEFF Research Database (Denmark)

    Thomsen, M S; Mikkelsen, J D; Timmermann, D B

    2008-01-01

    Due to the cognitive-enhancing properties of alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) agonists, they have attracted interest for the treatment of cognitive disturbances in schizophrenia. Schizophrenia typically presents in late adolescence or early adulthood. It is therefore important...... to study whether alpha7 nAChR stimulation activates brain regions involved in cognition in juvenile as well as adult individuals. Here, we compared the effects of the novel and selective alpha7 nAChR agonist 2-methyl-5-(6-phenyl-pyridazin-3-yl)-octahydro-pyrrolo[3,4-c]pyrrole (A-582941) in the juvenile...... regions critically involved in working memory and attention. Furthermore, this effect is more pronounced in juvenile than adult rats, indicating that the juvenile forebrain is more responsive to alpha7 nAChR stimulation. This observation may be relevant in the treatment of juvenile-onset schizophrenia....

  17. [11C]CHIBA-1001 as a novel PET ligand for alpha7 nicotinic receptors in the brain: a PET study in conscious monkeys.

    Directory of Open Access Journals (Sweden)

    Kenji Hashimoto

    Full Text Available BACKGROUND: The alpha7 nicotinic acetylcholine receptors (nAChRs play an important role in the pathophysiology of neuropsychiatric diseases such as schizophrenia and Alzheimer's disease. However, there are currently no suitable positron emission tomography (PET radioligands for imaging alpha7 nAChRs in the intact human brain. Here we report the novel PET radioligand [11C]CHIBA-1001 for in vivo imaging of alpha7 nAChRs in the non-human primate brain. METHODOLOGY/PRINCIPAL FINDINGS: A receptor binding assay showed that CHIBA-1001 was a highly selective ligand at alpha7 nAChRs. Using conscious monkeys, we found that the distribution of radioactivity in the monkey brain after intravenous administration of [11C]CHIBA-1001 was consistent with the regional distribution of alpha7 nAChRs in the monkey brain. The distribution of radioactivity in the brain regions after intravenous administration of [11C]CHIBA-1001 was blocked by pretreatment with the selective alpha7 nAChR agonist SSR180711 (5.0 mg/kg. However, the distribution of [11C]CHIBA-1001 was not altered by pretreatment with the selective alpha4beta2 nAChR agonist A85380 (1.0 mg/kg. Interestingly, the binding of [11C]CHIBA-1001 in the frontal cortex of the monkey brain was significantly decreased by subchronic administration of the N-methyl-D-aspartate (NMDA receptor antagonist phencyclidine (0.3 mg/kg, twice a day for 13 days; which is a non-human primate model of schizophrenia. CONCLUSIONS/SIGNIFICANCE: The present findings suggest that [11C]CHIBA-1001 could be a novel useful PET ligand for in vivo study of the receptor occupancy and pathophysiology of alpha7 nAChRs in the intact brain of patients with neuropsychiatric diseases such as schizophrenia and Alzheimer's disease.

  18. Effects of cigarette smoke exposure on nicotinic acetylcholine receptor subunits {alpha}7 and {beta}2 in the sudden infant death syndrome (SIDS) brainstem

    Energy Technology Data Exchange (ETDEWEB)

    Machaalani, Rita, E-mail: rita.machaalani@sydney.edu.au [Department of Medicine, The University of Sydney, NSW 2006 (Australia); Bosch Institute, The University of Sydney, NSW 2006 (Australia); The Children' s Hospital at Westmead, NSW 2145 (Australia); Say, Meichien [Department of Medicine, The University of Sydney, NSW 2006 (Australia); Bosch Institute, The University of Sydney, NSW 2006 (Australia); Waters, Karen A. [Department of Medicine, The University of Sydney, NSW 2006 (Australia); Bosch Institute, The University of Sydney, NSW 2006 (Australia); The Children' s Hospital at Westmead, NSW 2145 (Australia)

    2011-12-15

    It is postulated that nicotine, as the main neurotoxic constituent of cigarette smoke, influences SIDS risk through effects on nicotinic acetylcholine receptors (nAChRs) in brainstem nuclei that control respiration and arousal. This study compared {alpha}7 and {beta}2 nAChR subunit expression in eight nuclei of the caudal and rostral medulla and seven nuclei of the pons between SIDS (n = 46) and non-SIDS infants (n = 14). Evaluation for associations with known SIDS risk factors included comparison according to whether infants had a history of exposure to cigarette smoke in the home, and stratification for sleep position and gender. Compared to non-SIDS infants, SIDS infants had significantly decreased {alpha}7 in the caudal nucleus of the solitary tract (cNTS), gracile and cuneate nuclei, with decreased {beta}2 in the cNTS and increased {beta}2 in the facial. When considering only the SIDS cohort: 1-cigarette smoke exposure was associated with increased {alpha}7 in the vestibular nucleus and increased {beta}2 in the rostral dorsal motor nucleus of the vagus, rNTS and Cuneate, 2-there was a gender interaction for {alpha}7 in the gracile and cuneate, and {beta}2 in the cNTS and rostral arcuate nucleus, and 3-there was no effect of sleep position on {alpha}7, but prone sleep was associated with decreased {beta}2 in three nuclei of the pons. In conclusion, SIDS infants demonstrate differences in expression of {alpha}7 and {beta}2 nAChRs within brainstem nuclei that control respiration and arousal, which is independent on prior history of cigarette smoke exposure, especially for the NTS, with additional differences for smoke exposure ({beta}2), gender ({alpha}7 and {beta}2) and sleep position ({beta}2) evident. -- Highlights: Black-Right-Pointing-Pointer The 'normal' response to smoke exposure is decreased {alpha}7 and {beta}2 in certain nuclei. Black-Right-Pointing-Pointer SIDS infants have decreased {alpha}7 in cNTS, Grac and Cun. Black

  19. Cooperative regulation of non-small cell lung carcinoma by nicotinic and beta-adrenergic receptors: a novel target for intervention.

    Directory of Open Access Journals (Sweden)

    Hussein A N Al-Wadei

    Full Text Available Lung cancer is the leading cause of cancer death; 80-85% of lung cancer cases are non-small cell lung cancer (NSCLC. Smoking is a documented risk factor for the development of this cancer. Although nicotine does not have the ability to initiate carcinogenic events, recent studies have implicated nicotine in growth stimulation of NSCLC. Using three NSCLC cell lines (NCI-H322, NCI-H441 and NCI-H1299, we identified the cooperation of nicotinic acetylcholine receptors (nAChRs and β-adrenergic receptors (β-ARs as principal regulators of these effects. Proliferation was measured by thymidine incorporation and MTT assays, and Western blots were used to monitor the upregulation of the nAChRs and activation of signaling molecules. Noradrenaline and GABA were measured by immunoassays. Nicotine-treated NSCLC cells showed significant induction of the α7nAChR and α4nAChR, along with significant inductions of p-CREB and p-ERK1/2 accompanied by increases in the stress neurotransmitter noradrenaline, which in turn led to the observed increase in DNA synthesis and cell proliferation. Effects on cell proliferation and signaling proteins were reversed by the α7nAChR antagonist α-BTX or the β-blocker propranolol. Nicotine treatment also down-regulated expression of the GABA synthesizing enzyme GAD 65 and the level of endogenous GABA, while treatment of NSCLC cells with GABA inhibited cell proliferation. Interestingly, GABA acts by reducing β-adrenergic activated cAMP signaling. Our findings suggest that nicotine-induced activation of this autocrine noradrenaline-initiated signaling cascade and concomitant deficiency in inhibitory GABA, similar to modulation of these neurotransmitters in the nicotine-addicted brain, may contribute to the development of NSCLC in smokers. Our data suggest that exposure to nicotine either by tobacco smoke or nicotine supplements facilitates growth and progression of NSCLC and that pharmacological intervention by β blocker may

  20. Imidacloprid, thiacloprid, and their imine derivatives up-regulate the alpha 4 beta 2 nicotinic acetylcholine receptor in M10 cells.

    Science.gov (United States)

    Tomizawa, M; Casida, J E

    2000-11-15

    Neonicotinoids are the most important new class of insecticides of the last decade. They act as nicotinic acetylcholine receptor (AChR) agonists. This investigation tests the hypothesis for the first time that neonicotinoid insecticides and their imine derivatives up-regulate the alpha 4 beta 2 nicotinic AChR subtype, which represents >90% of the high-affinity [(3)H]nicotine binding sites in mammalian brain. The alpha 4 beta 2 receptor stably expressed in mouse fibroblast M10 cells was assayed after 3 days' exposure to the test compound, as [(3)H]nicotine binding following immunoisolation by monoclonal antibody (mAb 299) or as [(125)I]mAb 299 labeling for cell surface receptors. We found that imidacloprid (IMI) (one of the most important insecticides) and thiacloprid (THIA) increased [(3)H]nicotine binding levels (up-regulation of the alpha 4 beta 2 AChRs) by five- to eightfold with EC50s of approximately 70,000 and 19,000 nM, respectively, compared with 760 nM for (-)-nicotine. In contrast, two imine analogs [the desnitro metabolite of IMI (DNIMI) and the descyano derivative of THIA] gave up-regulation by eightfold and EC50s of 870 and 500 nM, respectively. The potency order for up-regulation by the five aforementioned compounds was correlated with their in vitro IC50s for inhibiting [(3)H]nicotine binding (r(2) = 0.99, n = 5), indicating that binding to the alpha 4 beta 2 receptor initiates the up-regulation. A potent olefin derivative of the THIA imine up-regulated with an EC50 of 22 nM. DNIMI-induced up-regulation mainly occurred intracellularly rather than at the cell surface. These findings in alpha 4 beta 2-expressing M10 cells indicate the possibility that some neonicotinoid insecticides or their metabolites, on accidental human exposure or when used for flea control on dogs, may also up-regulate the receptor in mammals. Copyright 2000 Academic Press.

  1. The interaction between alpha 7 nicotinic acetylcholine receptor and nuclear peroxisome proliferator-activated receptor-α represents a new antinociceptive signaling pathway in mice.

    Science.gov (United States)

    Donvito, Giulia; Bagdas, Deniz; Toma, Wisam; Rahimpour, Elnaz; Jackson, Asti; Meade, Julie A; AlSharari, Shakir; Kulkarni, Abhijit R; Ivy Carroll, F; Lichtman, Aron H; Papke, Roger L; Thakur, Ganesh A; Imad Damaj, M

    2017-09-01

    Recently, α7 nicotinic acetylcholine receptors (nAChRs), primarily activated by binding of orthosteric agonists, represent a target for anti-inflammatory and analgesic drug development. These receptors may also be modulated by positive allosteric modulators (PAMs), ago-allosteric ligands (ago-PAMs), and α7-silent agonists. Activation of α7 nAChRs has been reported to increase the brain levels of endogenous ligands for nuclear peroxisome proliferator-activated receptors type-α (PPAR-α), palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), in a Ca2+-dependent manner. Here, we investigated potential crosstalk between α7 nAChR and PPAR-α, using the formalin test, a mouse model of tonic pain. Using pharmacological and genetic approaches, we found that PNU282987, a full α7 agonist, attenuated formalin-induced nociceptive behavior in α7-dependent manner. Interestingly, the selective PPAR-α antagonist GW6471 blocked the antinociceptive effects of PNU282987, but did not alter the antinociceptive responses evoked by the α7 nAChR PAM PNU120596, ago-PAM GAT107, and silent agonist NS6740. Moreover, GW6471 administered systemically or spinally, but not via the intraplantar surface of the formalin-injected paw blocked PNU282987-induced antinociception. Conversely, exogenous administration of the naturally occurring PPAR-α agonist PEA potentiated the antinociceptive effects of PNU282987. In contrast, the cannabinoid CB1 antagonist rimonabant and the CB2 antagonist SR144528 failed to reverse the antinociceptive effects of PNU282987. These findings suggest that PPAR-α plays a key role in a putative antinociceptive α7 nicotinic signaling pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Role of ventrolateral orbital cortex muscarinic and nicotinic receptors in modulation of capsaicin-induced orofacial pain-related behaviors in rats.

    Science.gov (United States)

    Tamaddonfard, Esmaeal; Erfanparast, Amir; Abbas Farshid, Amir; Delkhosh-Kasmaie, Fatmeh

    2017-09-29

    Acetylcholine, as a major neurotransmitter, mediates many brain functions such as pain. This study was aimed to investigate the effects of microinjection of muscarinic and nicotinic acetylcholine receptor antagonists and agonists into the ventrolateral orbital cortex (VLOC) on capsaicin-induced orofacial nociception and subsequent hyperalgesia. The right side of VLOC was surgically implanted with a guide cannula in anaesthetized rats. Orofacial pain-related behaviors were induced by subcutaneous injection of a capsaicin solution (1.5µg/20µl) into the left vibrissa pad. The time spent face rubbing with ipsilateral forepaw and general behavior were recorded for 10min, and then mechanical hyperalgesia was determined using von Frey filaments at 15, 30, 45 and 60min post-capsaicin injection. Alone intra-VLOC microinjection of atropine (a muscarinic acetylcholine receptor antagonist) and mecamylamine (a nicotinic acetylcholine receptor antagonist) at a similar dose of 200ng/site did not alter nocifensive behavior and hyperalgesia. Microinjection of oxotremorine (a muscarinic acetylcholine receptor agonist) at doses of 50 and 100ng/site and epibatidine (a nicotinic acetylcholine receptor agonist) at doses of 12.5, 25, 50 and 100ng/site into the VLOC suppressed pain-related behaviors. Prior microinjections of 200ng/site atropine and mecamylamine (200ng/site) prevented oxotremorine (100ng/site)-, and epibatidine (100ng/site)-induced antinociception, respectively. None of the above-mentioned chemicals changed general behavior. These results showed that the VLOC muscarinic and nicotinic acetylcholine receptors might be involved in modulation of orofacial nociception and hypersensitivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Melatonin protects uterus and oviduct exposed to nicotine in mice

    Directory of Open Access Journals (Sweden)

    Seyed Saadat Seyedeh Nazanin

    2014-03-01

    Full Text Available Smoking is associated with higher infertility risk. The aim of this study was to evaluate protective effects of melatonin on the uterus and oviduct in mice exposed to nicotine. Adult female mice (n=32 were divided into four groups. Group A: control animals received normal saline, Group B: injected with nicotine 40 μg/kg, Group C: injected with melatonin 10 μg, Group D: injected with nicotine 40 μg/kg and melatonin 10 μg. All animals were treated over 15 days intraperitoneally. On the 16th day, animals in the estrus phase were dissected and their uterus and oviducts were removed. Immunohistochemistry was recruited for studying apoptosis and for detection of estrogen receptor (ER alpha in luminal epithelium of the uterus and oviduct. Enzyme-linked immunosorbent assay was used for serum estradiol level determination. Nicotine in group B decreased estradiol level and ERalpha numbers both in the uterus and oviduct (p<0.05. Co-administration of melatonin-nicotine in Group D ameliorated the histology of the uterus and oviduct, increased ERalpha numbers and reduced apoptosis in the uterus and oviduct compared with the nicotine Group B (p<0.05. This study indicates that nicotine impairs the histology of the uterus and oviduct and co-administration of melatonin-nicotine ameliorates these findings, partly through alteration in ERalpha numbers and reduction of apoptosis

  4. Enhanced nicotine self-administration and suppressed dopaminergic systems in a rat model of diabetes.

    Science.gov (United States)

    O'Dell, Laura E; Natividad, Luis A; Pipkin, Joseph A; Roman, Francisco; Torres, Ivan; Jurado, Jesus; Torres, Oscar V; Friedman, Theodore C; Tenayuca, John M; Nazarian, Arbi

    2014-11-01

    Patients with diabetes display a heightened propensity to use tobacco; however, it is unclear whether they experience enhanced rewarding effects of nicotine. Thus, this study examined the reinforcing effects of nicotine in a rodent model of diabetes involving administration of streptozotocin (STZ), a drug that is toxic to pancreatic insulin-producing cells. The first study compared STZ- and vehicle-treated rats that had 23-hour access to intravenous self-administration (IVSA) of nicotine or saline and concomitant access to food and water. In order to examine the contribution of dopamine to our behavioral effects, dopamine transporter (DAT), D1 and D2 receptor levels were compared in the nucleus accumbens (NAc) following 10 days of nicotine or saline IVSA. Dopamine levels in the NAc were also compared following nicotine administration. Lastly, nicotine metabolism and dose-dependent effects of nicotine IVSA were assessed. The results revealed that STZ-treated rats displayed enhanced nicotine intake and a robust increase in food and water intake relative to controls. Protein analysis revealed an increase in DAT and a decrease in D1 receptor levels in the NAc of STZ- versus vehicle-treated rats regardless of IVSA condition. STZ-treated rats also displayed suppressed NAc dopamine levels during baseline and in response to nicotine. STZ treatment did not alter our assessment of nicotine metabolism. Furthermore, STZ treatment increased nicotine IVSA in a dose-dependent manner. Our findings suggest that STZ-treatment increased the rewarding effects of nicotine. This suggests that strong reinforcing effects of nicotine may contribute to greater tobacco use in patients with diabetes. © 2013 Society for the Study of Addiction.

  5. The Ascaris suum nicotinic receptor, ACR-16, as a drug target: Four novel negative allosteric modulators from virtual screening.

    Science.gov (United States)

    Zheng, Fudan; Robertson, Alan P; Abongwa, Melanie; Yu, Edward W; Martin, Richard J

    2016-04-01

    Soil-transmitted helminth infections in humans and livestock cause significant debility, reduced productivity and economic losses globally. There are a limited number of effective anthelmintic drugs available for treating helminths infections, and their frequent use has led to the development of resistance in many parasite species. There is an urgent need for novel therapeutic drugs for treating these parasites. We have chosen the ACR-16 nicotinic acetylcholine receptor of Ascaris suum (Asu-ACR-16), as a drug target and have developed three-dimensional models of this transmembrane protein receptor to facilitate the search for new bioactive compounds. Using the human α7 nAChR chimeras and Torpedo marmorata nAChR for homology modeling, we defined orthosteric and allosteric binding sites on the Asu-ACR-16 receptor for virtual screening. We identified four ligands that bind to sites on Asu-ACR-16 and tested their activity using electrophysiological recording from Asu-ACR-16 receptors expressed in Xenopus oocytes. The four ligands were acetylcholine inhibitors (SB-277011-A, IC50, 3.12 ± 1.29 μM; (+)-butaclamol Cl, IC50, 9.85 ± 2.37 μM; fmoc-1, IC50, 10.00 ± 1.38 μM; fmoc-2, IC50, 16.67 ± 1.95 μM) that behaved like negative allosteric modulators. Our work illustrates a structure-based in silico screening method for seeking anthelmintic hits, which can then be tested electrophysiologically for further characterization.

  6. Pharmacological differences between rat frontal cortex and hippocampus in the nicotinic modulation of noradrenaline release implicate distinct receptor subtypes.

    Science.gov (United States)

    Kennett, Alexandra; Heal, David J; Wonnacott, Susan

    2012-11-01

    Noradrenergic mechanisms in frontal cortex and hippocampus are relevant to attentional and stress-related aspects of addiction, respectively. Nicotinic receptors (nAChRs) modulate the release of noradrenaline (NA) in these tissues. This study determined if similar subtypes of nAChR regulate NA release in rat frontal cortex and hippocampus. The release of [(3)H]-NA from rat tissue prisms was characterized in a 96-well plate assay. In vivo microdialysis was used to monitor NA overflow from rat frontal cortex and hippocampus in conscious freely moving rats. [(3)H]-NA release from frontal cortex prisms was more sensitive to nicotinic agonists than release from hippocampal prisms. The β2-selective agonist 5-iodo-A-85380 was 1000-fold more potent in frontal cortex compared with hippocampus. Agonist-evoked [(3)H]-NA release was inhibited by the β2-selective antagonist dihydro-beta-erythroidine (DHβE) in frontal cortex, whereas in hippocampal tissue, DHβE had no effect. In vivo, 5-iodo-A-85380 (1, 100 μM) applied locally via the dialysis probe, significantly increased NA overflow, compared with basal release, in frontal cortex but not in hippocampus. These data support the modulation of NA release by different nAChR subtypes in frontal cortex and hippocampus. The pharmacological profile for rat hippocampus is consistent with previous studies, implicating α3β4* nAChRs in the modulation of NA release in this tissue. nAChRs having this function in frontal cortex are pharmacologically distinct and correspond to β2-containing nAChRs.

  7. Inhibition of the nicotinic acetylcholine receptors by cobra venom α-neurotoxins: is there a perspective in lung cancer treatment?

    Directory of Open Access Journals (Sweden)

    Angela Alama

    Full Text Available Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis. The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy. However, since part of the published results was recently retracted, we believe that the antitumoral activity of cobra venom neurotoxins needs to be independently re-evaluated.We determined the activity of α-neurotoxins from Naja atra (short-chain neurotoxin, α-cobrotoxin and Naja kaouthia (long-chain neurotoxin, α-cobratoxin in vitro by cytotoxicity measurements in 5 lung cancer cell lines, by colony formation assay with α7nAChRs expressing and non-expressing cell lines and in vivo by assessing tumor growth in an orthotopic Non-Obese Diabetic/Severe Combined Immunodeficient (NOD/SCID mouse model system utilizing different treatment schedules and dosages.No statistically significant reduction in tumor growth was observed in the treatment arms in comparison to the control for both toxins. Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

  8. {alpha}4 {beta}2 nicotinic acetylcholine receptor in Alzheimer's disease and mild cognitive impairment: a study with 5-[I-123]iodo-A-85380 SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Park, Eun Kyung; Kim, Yu Kyeong; Kim, Sang Yun; Kim, Sang Eun [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2007-07-01

    It has been reported that the number of neuronal nicotinic acetylcholine receptors (nAChRs) is decreased in Alzheimer's disease (AD) and the degree of cholinergic deficit is correlated with cognitive impairment. We examined neuronal nAChR distribution of AD patients using 5-[I-123]iodo-A85380 (5-IA) SPECT and correlated it with the pattern of cerebral glucose metabolic impairment and the severity of cognitive impairment. Five clinically diagnosed AD patients, 5 amnestic mild cognitive impairment (MCI) patients, and 10 age- and sex-matched healthy controls were studied with 5-IA SPECT and brain FDG PET. 5-IA SPECT was performed for 30 min at 120 min after radiotracer injection. FDG PET was done within one month interval. Neuropsychological tests were done for cognitive evaluation. A nAChR parameter DV was calculated in brain regions using cerebellum as reference tissue. All scan images were analyzed using SPM2 and ANOVA was done for group comparison. P value less than 0.005 was considered significant. 5-IA SPECT images of AD patients revealed significantly reduced nAChR distribution in the anterior cingulate cortex, striatum, and the left temporal cortex. MCI patients demonstrated decreased receptor distribution mainly in the subcortical areas. Cortical nAChR distribution showed correlation with cortical glucose metabolism and subcortical with that of posterior cingulate cortex (PCC). Episodic memory and semantic verbal fluency showed significant correlation with nAChR distribution of periventricular white matter (PVWM), visuospatial function evaluated with RCFT with that of PCC, left temporoparietal cortex, and frontal lobe white matter, and MMSE with that of PVWM, frontal cortex, and striatum. These data demonstrate reduction of nAChR distribution in patients with AD, which has significant correlation with cerebral glucose metabolism and cognitive impairment. It might be useful for diagnosis of AD, and for monitoring individualized treatments targeted at nAChRs.

  9. Nicotine analog inhibition of nicotine self-administration in rats.

    Science.gov (United States)

    Rowland, Neil E; Robertson, Kimberly; Soti, Ferenc; Kem, William R

    2008-09-01

    Partial agonists and antagonists of addictive drugs have been useful in the treatment of dependence. The purpose of this study is to determine whether nicotine analogs with partial agonist or antagonist properties at alpha4beta2 nicotinic acetylcholine receptors (nAChRs) inhibit self-administration of nicotine in rats. Male Sprague-Dawley rats were trained to self-administer nicotine (unit dose 0.017 mg/kg) intravenously contingent upon the completion of five lever presses. Once stable responding was established, rats were administered test agents, either as a subcutaneous injection before the daily session or co-infused with nicotine. The number of nicotine injections taken per session was reduced to approximately 50% of baseline after either pre-treatment with the broad spectrum nicotinic receptor antagonist, mecamylamine, or by substituting saline for nicotine (extinction). 4'-Trans-methyl-nicotine, a strong partial agonist, inhibited nicotine self-administration and substituted for nicotine to support self-administration. Partial agonists, prepared by substitution at the 1'-N-position with either ethyl or cyclopropylmethyl moieties, potently inhibited self-administration. Antagonists formed by 5'-methyl substitution also inhibited self-administration, with the 5'-trans-methyl enantiomer about ten times more potent than the 5'-cis-methyl enantiomer. In contrast, antagonists formed by aryl substitution at the 5 position of the pyridyl ring of nicotine did not inhibit self-administration. Intravenous co-infusions had similar effects to the pre-injections. In most instances, doses of the analogs that reduced nicotine self-administration had no effect on food intake when measured using a similar FR5 protocol. Nicotine analogs with alpha4beta2 nAChR partial agonist and antagonist efficacies can inhibit self-administration and may be considered as prototypical smoking-cessation agents.

  10. Bupropion-induced inhibition of α7 nicotinic acetylcholine receptors expressed in heterologous cells and neurons from dorsal raphe nucleus and hippocampus.

    Science.gov (United States)

    Vázquez-Gómez, Elizabeth; Arias, Hugo R; Feuerbach, Dominik; Miranda-Morales, Marcela; Mihailescu, Stefan; Targowska-Duda, Katarzyna M; Jozwiak, Krzysztof; García-Colunga, Jesús

    2014-10-05

    The pharmacological activity of bupropion was compared between α7 nicotinic acetylcholine receptors expressed in heterologous cells and hippocampal and dorsal raphe nucleus neurons. The inhibitory activity of bupropion was studied on GH3-α7 cells by Ca2+ influx, as well as on neurons from the dorsal raphe nucleus and interneurons from the stratum radiatum of the hippocampal CA1 region by using a whole-cell voltage-clamp technique. In addition, the interaction of bupropion with the α7 nicotinic acetylcholine receptor was determined by [3H]imipramine competition binding assays and molecular docking. The fast component of acetylcholine- and choline-induced currents from both brain regions was inhibited by methyllycaconitine, indicating the participation of α7-containing nicotinic acetylcholine receptors. Choline-induced currents in hippocampal interneurons were partially inhibited by 10 µM bupropion, a concentration that could be reached in the brain during clinical administration. Additionally, both agonist-induced currents were reversibly inhibited by bupropion at concentrations that coincide with its inhibitory potency (IC50=54 µM) and binding affinity (Ki=63 µM) for α7 nicotinic acetylcholine receptors from heterologous cells. The [3H]imipramine competition binding and molecular docking results support a luminal location for the bupropion binding site(s). This study may help to understand the mechanisms of actions of bupropion at neuronal and molecular levels related with its therapeutic actions on depression and for smoking cessation. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Effects of Prenatal Exposure to Nicotine on Working Memory, Activity, Sensory Gating, and Dopamine Receptor Binding in Adolescent and Adult Male and Female Rats

    Science.gov (United States)

    1999-01-08

    ancient Greece when the philosopher Plato made his bird-brain analogy ( Eysenck et aI., 1995). In this analogy, memory was likened to a birdhouse, the...most widely used forms of human memory functioning ( Eysenck et aI., 1995). Another argument against 20 the utility of using animals to study...34Effects of Prenatal Exposure to Nicotine on Working Memory , Activity , Sensory Gating, and Dopamine Receptor Binding in Adolescent and Adult Male

  12. Natural Compounds Interacting with Nicotinic Acetylcholine Receptors: From Low-Molecular Weight Ones to Peptides and Proteins

    Directory of Open Access Journals (Sweden)

    Denis Kudryavtsev

    2015-05-01

    Full Text Available Nicotinic acetylcholine receptors (nAChRs fulfill a variety of functions making identification and analysis of nAChR subtypes a challenging task. Traditional instruments for nAChR research are d-tubocurarine, snake venom protein α-bungarotoxin (α-Bgt, and α-conotoxins, neurotoxic peptides from Conus snails. Various new compounds of different structural classes also interacting with nAChRs have been recently identified. Among the low-molecular weight compounds are alkaloids pibocin, varacin and makaluvamines C and G. 6-Bromohypaphorine from the mollusk Hermissenda crassicornis does not bind to Torpedo nAChR but behaves as an agonist on human α7 nAChR. To get more selective α-conotoxins, computer modeling of their complexes with acetylcholine-binding proteins and distinct nAChRs was used. Several novel three-finger neurotoxins targeting nAChRs were described and α-Bgt inhibition of GABA-A receptors was discovered. Information on the mechanisms of nAChR interactions with the three-finger proteins of the Ly6 family was found. Snake venom phospholipases A2 were recently found to inhibit different nAChR subtypes. Blocking of nAChRs in Lymnaea stagnalis neurons was shown for venom C-type lectin-like proteins, appearing to be the largest molecules capable to interact with the receptor. A huge nAChR molecule sensible to conformational rearrangements accommodates diverse binding sites recognizable by structurally very different compounds.

  13. Alpha7 nicotinic acetylcholine receptor is required for amyloid pathology in brain endothelial cells induced by Glycoprotein 120, methamphetamine and nicotine

    OpenAIRE

    Liqun Liu; Jingyi Yu; Li Li; Bao Zhang; Lingjuan Liu; Chun-Hua Wu; Ambrose Jong; Ding-An Mao; Sheng-He Huang

    2017-01-01

    One of the most challenging issues in HIV-associated neurocognitive disorders (HAND) caused by HIV-1 virotoxins and drug abuse is the lack of understanding the underlying mechanisms that are commonly associated with disorders of the blood-brain barrier (BBB), which mainly consists of brain microvascular endothelial cells (BMEC). Here, we hypothesized that Glycoprotein 120 (gp120), methamphetamine (METH) and nicotine (NT) can enhance amyloid-beta (A?) accumulation in BMEC through Alpha7 nicoti...

  14. Pharmacology of nicotine: addiction, smoking-induced disease, and therapeutics.

    Science.gov (United States)

    Benowitz, Neal L

    2009-01-01

    Nicotine sustains tobacco addiction, a major cause of disability and premature death. Nicotine binds to nicotinic cholinergic receptors, facilitating neurotransmitter release and thereby mediating the complex actions of nicotine in tobacco users. Dopamine, glutamate, and gamma aminobutyric acid release are particularly important in the development of nicotine dependence, and corticotropin-releasing factor appears to contribute to nicotine withdrawal. Nicotine dependence is highly heritable. Genetic studies indicate roles for nicotinic receptor subtypes, as well as genes involved in neuroplasticity and learning, in development of dependence. Nicotine is primarily metabolized by CYP 2A6, and variability in rate of metabolism contributes to vulnerability to tobacco dependence, response to smoking cessation treatment, and lung cancer risk. Tobacco addiction is much more common in persons with mental illness and substance abuse disorders, representing a high proportion of current smokers. Pharmacotherapeutic approaches to tobacco addiction include nicotine replacement, bupropion, and varenicline, the latter a selective nicotine receptor partial agonist.

  15. Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis.

    Science.gov (United States)

    Liu, Qiang; Whiteaker, Paul; Morley, Barbara J; Shi, Fu-Dong; Lukas, Ronald J

    2017-01-01

    Previous studies have demonstrated immunosuppressive and anti-inflammatory effects of nicotine, including in the experimental autoimmune encephalomyelitis (EAE) model in mice of some forms of multiple sclerosis (MS). Other studies using knock-out (KO) mice have implicated nicotinic acetylcholine (ACh) receptors containing α7, α9, or β2 subunits (α7*-, α9*- or β2*-nAChR) in different, disease-exacerbating or disease-ameliorating processes. These outcomes are in harmony with gene expression analyses showing nAChR subunit mRNA in many classes of immune system cell types. Consistent with influences on disease status, predictable effects of nAChR subunit (and subtype) KO, or of nicotine exposure, are seen on immune cell numbers and distribution and on cytokine levels or other markers of immunity, inflammation, demyelination, and axonal degradation. Providing support for our hypotheses about distinctive roles for nAChR subtypes in EAE, here we have used direct and adoptive EAE induction and a nAChR subunit gene double knock-out (DKO) strategy. Immune cell expression of nAChR α9 subunits as protein is demonstrated by immunostaining of isolated CD4+, CD8+, CD11b+ and CD11c+ cells from wild-type (WT) mice, but not in cells from nAChR α9 subunit KO animals. Nicotine exposure is protective against directly-induced EAE in WT or α7/α9 DKO animals relative to effects seen in WT/vehicle-treated mice, but, remarkably, EAE is exacerbated in vehicle-treated α7/α9 DKO mice. Brain lesion volume and intra-cranial inflammatory activity similarly are higher in DKO/vehicle than in WT/vehicle-treated animals, although nicotine's protective effects are seen in each instance. By contrast, in adoptive transfer studies, disease severity is attenuated and disease onset is delayed in recipients of splenocytes from WT animals treated with nicotine rather than with vehicle. Moreover, protection as seen in nicotine-treated WT animals is the same in recipients of splenocytes from nAChR

  16. Nicotinic Receptor Abnormalities in the Cerebellar Cortex of Sudden Unexplained Fetal and Infant Death Victims-Possible Correlation With Maternal Smoking.

    Science.gov (United States)

    Lavezzi, Anna M; Ferrero, Stefano; Roncati, Luca; Piscioli, Francesco; Matturri, Luigi; Pusiol, Teresa

    2017-01-01

    Nicotinic acetylcholine receptors (nAChRs) are cationic channels of the neuronal cell membrane, differentially expressed in the central nervous system which, when activated by endogenous acetylcholine or exogenous nicotine, are able to enhance cholinergic transmission. The aim of this study was to investigate in human perinatal age the immunohistochemical expression of the α7-nAChR subtype, given its involvement in neuronal differentiation and its significant vulnerability to the toxic effects of nicotine. Thirty fetuses (with a gestational age between 25 and 40 weeks) and 35 infants (1-6 months old), suddenly died of known (controls) and unknown causes (unexplained deaths), with smoking and nonsmoking mothers, were included in this study. A negative or low immunoexpression of α7-nAChRs, indicative of their inactivation, was observed in the granular layers of the cerebellar cortex in 66% of the sudden unexplained perinatal deaths and 11% of the controls. A high correlation was also observed between these findings and maternal smoking. Apart from the well-known adverse effects of nicotine exposure during pregnancy, it may also cause significant alterations in cerebellar cholinergic transmission in areas of the brain involved in vital functions. These events may give us insights into the pathogenetic mechanisms leading to sudden unexplained fetal and infant death.

  17. α7 Nicotinic acetylcholine receptor-specific antibody induces inflammation and amyloid β42 accumulation in the mouse brain to impair memory.

    Directory of Open Access Journals (Sweden)

    Olena Lykhmus

    Full Text Available Nicotinic acetylcholine receptors (nAChRs expressed in the brain are involved in regulating cognitive functions, as well as inflammatory reactions. Their density is decreased upon Alzheimer disease accompanied by accumulation of β-amyloid (Aβ42, memory deficit and neuroinflammation. Previously we found that α7 nAChR-specific antibody induced pro-inflammatory interleukin-6 production in U373 glioblastoma cells and that such antibodies were present in the blood of humans. We raised a hypothesis that α7 nAChR-specific antibody can cause neuroinflammation when penetrating the brain. To test this, C57Bl/6 mice were either immunized with extracellular domain of α7 nAChR subunit α7(1-208 or injected with bacterial lipopolysaccharide (LPS for 5 months. We studied their behavior and the presence of α3, α4, α7, β2 and β4 nAChR subunits, Aβ40 and Aβ42 and activated astrocytes in the brain by sandwich ELISA and confocal microscopy. It was found that either LPS injections or immunizations with α7(1-208 resulted in region-specific decrease of α7 and α4β2 and increase of α3β4 nAChRs, accumulation of Aβ42 and activated astrocytes in the brain of mice and worsening of their episodic memory. Intravenously transferred α7 nAChR-specific-antibodies penetrated the brain parenchyma of mice pre-injected with LPS. Our data demonstrate that (1 neuroinflammation is sufficient to provoke the decrease of α7 and α4β2 nAChRs, Aβ42 accumulation and memory impairment in mice and (2 α7(1-208 nAChR-specific antibodies can cause inflammation within the brain resulting in the symptoms typical for Alzheimer disease.

  18. Endothelin receptor B antagonists decrease glioma cell viability independently of their cognate receptor

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    Patterson Paul H

    2008-11-01

    Full Text Available Abstract Background Endothelin receptor antagonists inhibit the progression of many cancers, but research into their influence on glioma has been limited. Methods We treated glioma cell lines, LN-229 and SW1088, and melanoma cell lines, A375 and WM35, with two endothelin receptor type B (ETRB-specific antagonists, A-192621 and BQ788, and quantified viable cells by the capacity of their intracellular esterases to convert non-fluorescent calcein AM into green-fluorescent calcein. We assessed cell proliferation by labeling cells with carboxyfluorescein diacetate succinimidyl ester and quantifying the fluorescence by FACS analysis. We also examined the cell cycle status using BrdU/propidium iodide double staining and FACS analysis. We evaluated changes in gene expression by microarray analysis following treatment with A-192621 in glioma cells. We examined the role of ETRB by reducing its expression level using small interfering RNA (siRNA. Results We report that two ETRB-specific antagonists, A-192621 and BQ788, reduce the number of viable cells in two glioma cell lines in a dose- and time-dependent manner. We describe similar results for two melanoma cell lines. The more potent of the two antagonists, A-192621, decreases the mean number of cell divisions at least in part by inducing a G2/M arrest and apoptosis. Microarray analysis of the effects of A-192621 treatment reveals up-regulation of several DNA damage-inducible genes. These results were confirmed by real-time RT-PCR. Importantly, reducing expression of ETRB with siRNAs does not abrogate the effects of either A-192621 or BQ788 in glioma or melanoma cells. Furthermore, BQ123, an endothelin receptor type A (ETRA-specific antagonist, has no effect on cell viability in any of these cell lines, indicating that the ETRB-independent effects on cell viability exhibited by A-192621 and BQ788 are not a result of ETRA inhibition. Conclusion While ETRB antagonists reduce the viability of glioma cells

  19. Design, synthesis, and pharmacological characterization of novel spirocyclic quinuclidinyl-Delta2 -isoxazoline derivatives as potent and selective agonists of alpha7 nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Dallanoce, Clelia; Magrone, Pietro; Matera, Carlo

    2011-01-01

    A set of racemic spirocyclic quinuclidinyl-¿(2) -isoxazoline derivatives was synthesized using a 1,3-dipolar cycloaddition-based approach. Target compounds were assayed for binding affinity toward rat neuronal homomeric (a7) and heteromeric (a4ß2) nicotinic acetylcholine receptors. ¿(2) -Isoxazol......-L- or (-)-dibenzoyl-D-tartaric acid as resolving agents. Enantiomer (R)-(-)-6¿a was found to be the eutomer, with K(i) values of 4.6 and 48.7 nM against rat and human a7 receptors, respectively....

  20. Neuroimmune Interactions in Schizophrenia: Focus on Vagus Nerve Stimulation and Activation of the Alpha-7 Nicotinic Acetylcholine Receptor

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    Fabiana Maria das Graças Corsi-Zuelli

    2017-05-01

    Full Text Available Schizophrenia is one of the most debilitating mental disorders and is aggravated by the lack of efficacious treatment. Although its etiology is unclear, epidemiological studies indicate that infection and inflammation during development induces behavioral, morphological, neurochemical, and cognitive impairments, increasing the risk of developing schizophrenia. The inflammatory hypothesis of schizophrenia is also supported by clinical studies demonstrating systemic inflammation and microglia activation in schizophrenic patients. Although elucidating the mechanism that induces this inflammatory profile remains a challenge, mounting evidence suggests that neuroimmune interactions may provide therapeutic advantages to control inflammation and hence schizophrenia. Recent studies have indicated that vagus nerve stimulation controls both peripheral and central inflammation via alpha-7 nicotinic acetylcholine receptor (α7nAChR. Other findings have indicated that vagal stimulation and α7nAChR-agonists can provide therapeutic advantages for neuropsychiatric disorders, such as depression and epilepsy. This review analyzes the latest results regarding: (I the immune-to-brain pathogenesis of schizophrenia; (II the regulation of inflammation by the autonomic nervous system in psychiatric disorders; and (III the role of the vagus nerve and α7nAChR in schizophrenia.

  1. Nicotinic Acetylcholine Receptor Density in Cognitively Intact Subjects at an Early Stage of Parkinson’s Disease

    Science.gov (United States)

    Isaias, Ioannis Ugo; Spiegel, Jörg; Brumberg, Joachim; Cosgrove, Kelly P.; Marotta, Giorgio; Oishi, Naoya; Higuchi, Takahiro; Küsters, Sebastian; Schiller, Markus; Dillmann, Ulrich; van Dyck, Christopher H.; Buck, Andreas; Herrmann, Ken; Schloegl, Susanne; Volkmann, Jens; Lassmann, Michael; Fassbender, Klaus; Lorenz, Reinhard; Samnick, Samuel

    2014-01-01

    We investigated in vivo brain nicotinic acetylcholine receptor (nAChR) distribution in cognitively intact subjects with Parkinson’s disease (PD) at an early stage of the disease. Fourteen patients and 13 healthy subjects were imaged with single photon emission computed tomography and the radiotracer 5-[123I]iodo-3-[2(S)-2-azetidinylmethoxy]pyridine ([123I]5IA). Patients were selected according to several criteria, including short duration of motor signs (<7 years) and normal scores at an extensive neuropsychological evaluation. In PD patients, nAChR density was significantly higher in the putamen, the insular cortex and the supplementary motor area and lower in the caudate nucleus, the orbitofrontal cortex, and the middle temporal gyrus. Disease duration positively correlated with nAChR density in the putamen ipsilateral (ρ = 0.56, p < 0.05) but not contralateral (ρ = 0.49, p = 0.07) to the clinically most affected hemibody. We observed, for the first time in vivo, higher nAChR density in brain regions of the motor and limbic basal ganglia circuits of subjects with PD. Our findings support the notion of an up-regulated cholinergic activity at the striatal and possibly cortical level in cognitively intact PD patients at an early stage of disease. PMID:25177294

  2. Differential immediate and sustained memory enhancing effects of alpha7 nicotinic receptor agonists and allosteric modulators in rats

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; El-Sayed, Mona; Mikkelsen, Jens D

    2011-01-01

    The α7 nicotinic acetylcholine receptor (nAChR) is a potential target for the treatment of cognitive deficits in patients with schizophrenia, ADHD and Alzheimer's disease. Here we test the hypothesis that upregulation of α7 nAChR levels underlies the enhanced and sustained procognitive effect...... of repeated administration of α7 nAChR agonists. We further compare the effect of agonists to that of α7 nAChR positive allosteric modulators (PAMs), which do not induce upregulation of the α7 nAChR. Using the social discrimination test as a measure of short-term memory, we show that the α7 nAChR agonist A...... of agonists and PAMs that may be relevant for clinical development. Importantly, A-582941 and AVL-3288 increase short-term memory 24 hrs after repeated, but not a single, administration, suggesting that repeated administration of both agonists and PAMs may produce sustained effects on cognitive performance...

  3. Blockade of nicotinic and muscarinic receptors facilitates spontaneous migration of human peripheral granulocytes: failure in cystic fibrosis.

    Science.gov (United States)

    Wessler, Ignaz; Neumann, Stefanie; Razen, Michael; Zepp, Fred; Kirkpatrick, Charles James

    2012-11-27

    Circulating leucocytes express muscarinic (m) and nicotinic (n) receptors and synthesize acetylcholine (ACh) regulating various cell functions. Leucocytes from patients with cystic fibrosis contain less ACh; therefore it was tested whether the regulation of cellular functions like migration differed from healthy volunteers. Peripheral blood (10-20 ml) was used, leucocytes were isolated by Ficoll® gradient and the commercial MIGRATEST® combined with flow cytometric analysis was applied (pore size 3 μm). In the absence of test substances 4900±1800 (n=10) leucocytes migrated within a time period of 2 h. In the presence of tubocurarine (TC, 30 μM) the cell number increased to 7500±2700 [n=10] corresponding to an increase of 162±20% (mean of individual experiments; pGranulocytes isolated from patients with cystic fibrosis did not respond (2h migration) to 30 μM TC (control: 5180±1400 cells [n=10]; TC: 5800±1400 [n=10]). Also in the presence of atropine (1 μM) and TC (30 μM) a significant effect was not detected (5800±1300 [n=10]). Auto-paracrine acetylcholine limits the migration of unstimulated peripheral granulocytes. This effect is impaired in cystic fibrosis most likely because of a reduced endogenous cholinergic tone. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Effect of the Nicotinic α4β2-receptor Partial Agonist Varenicline on Non-invasive Brain Stimulation-Induced Neuroplasticity in the Human Motor Cortex.

    Science.gov (United States)

    Batsikadze, Giorgi; Paulus, Walter; Grundey, Jessica; Kuo, Min-Fang; Nitsche, Michael A

    2015-09-01

    Nicotine alters cognitive functions in animals and humans most likely by modification of brain plasticity. In the human brain, it alters plasticity induced by transcranial direct current stimulation (tDCS) and paired associative stimulation (PAS), probably by interference with calcium-dependent modulation of the glutamatergic system. We aimed to test this hypothesis further by exploring the impact of the α4β2-nicotinic receptor partial agonist varenicline on focal and non-focal plasticity, induced by PAS and tDCS, respectively. We administered low (0.1 mg), medium (0.3 mg), and high (1.0 mg) single doses of varenicline or placebo medication before PAS or tDCS on the left motor cortex of 25 healthy non-smokers. Corticospinal excitability was monitored by single-pulse transcranial magnetic stimulation-induced motor evoked potential amplitudes up to 36 h after plasticity induction. Whereas low-dose varenicline had no impact on stimulation-induced neuroplasticity, medium-dose abolished tDCS-induced facilitatory after-effects, favoring focal excitatory plasticity. High-dose application preserved cathodal tDCS-induced excitability diminution and focal excitatory PAS-induced facilitatory plasticity. These results are comparable to the impact of nicotine receptor activation and might help to further explain the involvement of specific receptor subtypes in the nicotinic impact on neuroplasticity and cognitive functions in healthy subjects and patients with neuropsychiatric diseases. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Beta amyloid differently modulate nicotinic and muscarinic receptor subtypes which regulate in vitro and in vivo the release of glycine in the rat hippocampus

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    Stefania eZappettini

    2012-07-01

    Full Text Available Using both in vitro (hippocampal synaptosomes in superfusion and in vivo (microdialysis approaches we investigated whether and to what extent β amyloid peptide 1-40 (Aβ 1-40 interferes with the cholinergic modulation of the release of glycine (GLY in the rat hippocampus. The nicotine-evoked overflow of endogenous GLY in hippocampal synaptosomes in superfusion was significantly inhibited by Aβ 1-40 (10 nM while increasing the concentration to 100 nM the inhibitory effect did not further increase. Both the Choline (Ch (α7 agonist; 1 mM and the 5-Iodo-A-85380 dihydrochloride (5IA85380, α4β2 agonist; 10 nM-evoked GLY overflow were inhibited by Aβ1-40 at 100 nM but not at 10nM concentrations. The KCl evoked [3H]GLY and [3H]Acetylcholine (ACh overflow were strongly inhibited in presence of oxotremorine; however this inhibitory muscarinic effect was not affected by Aβ1-40. The effects of Aβ1-40 on the administration of nicotine, veratridine, 5IA85380 and PHA 543613 hydrochloride (PHA543613 (a selective agonist of α7 subtypes on hippocampal endogenous GLY release in vivo were also studied. Aβ 1-40 significantly reduced (at 10 μM but not at 1 μM the nicotine evoked in vivo release of GLY. Aβ 1-40 (at 10 μM but not at 1 μM significantly inhibited the PHA543613 (1 mM-elicited GLY overflow while was ineffective on the GLY overflow evoked by 5IA85380 (1 mM. Aβ 40-1 (10 μM did not produce any inhibitory effect on nicotine evoked GLY overflow both in the in vitro and in vivo experiments. Our results indicate that a the cholinergic modulation of the release of GLY occurs by the activation of both α7 and α4β2 nicotinic ACh receptors (nAChRs as well as by the activation of inhibitory muscarinic ACh receptors (mAChRs and b Aβ 1-40 can modulate cholinergic evoked GLY release exclusively through the interaction with α7 and the α4β2 nAChR nicotinic receptors but not through mAChR subtypes.

  6. Nicotinic α4β2 Cholinergic Receptor Influences on Dorsolateral Prefrontal Cortical Neuronal Firing during a Working Memory Task.

    Science.gov (United States)

    Sun, Yongan; Yang, Yang; Galvin, Veronica C; Yang, Shengtao; Arnsten, Amy F; Wang, Min

    2017-05-24

    The primate dorsolateral prefrontal cortex (dlPFC) subserves top-down regulation of attention and working memory abilities. Depletion studies show that the neuromodulator acetylcholine (ACh) is essential to dlPFC working memory functions, but the receptor and cellular bases for cholinergic actions are just beginning to be understood. The current study found that nicotinic receptors comprised of α4 and β2 subunits (α4β2-nAChR) enhance the task-related firing of delay and fixation cells in the dlPFC of monkeys performing a working memory task. Iontophoresis of α4β2-nAChR agonists increased the neuronal firing and enhanced the spatial tuning of delay cells, neurons that represent visual space in the absence of sensory stimulation. These enhancing effects were reversed by coapplication of a α4β2-nAChR antagonist, consistent with actions at α4β2-nAChR. Delay cell firing was reduced when distractors were presented during the delay epoch, whereas stimulation of α4β2-nAChR protected delay cells from these deleterious effects. Iontophoresis of α4β2-nAChR agonists also enhanced the firing of fixation cells, neurons that increase firing when the monkey initiates a trial, and maintain firing until the trial is completed. These neurons are thought to contribute to sustained attention and top-down motor control and have never before been the subject of pharmacological inquiry. These findings begin to build a picture of the cellular actions underlying the beneficial effects of ACh on attention and working memory. The data may also help to explain why genetic insults to α4 subunits are associated with working memory and attentional deficits and why α4β2-nAChR agonists may have therapeutic potential.SIGNIFICANCE STATEMENT The acetylcholine (ACh) arousal system in the brain is needed for robust attention and working memory functions, but the receptor and cellular bases for its beneficial effects are poorly understood in the newly evolved primate brain. The current

  7. Financial and psychological risk attitudes associated with two single nucleotide polymorphisms in the nicotine receptor (CHRNA4 gene.

    Directory of Open Access Journals (Sweden)

    Brian E Roe

    2009-08-01

    Full Text Available With recent advances in understanding of the neuroscience of risk taking, attention is now turning to genetic factors that may contribute to individual heterogeneity in risk attitudes. In this paper we test for genetic associations with risk attitude measures derived from both the psychology and economics literature. To develop a long-term prospective study, we first evaluate both types of risk attitudes and find that the economic and psychological measures are poorly correlated, suggesting that different genetic factors may underlie human response to risk faced in different behavioral domains. We then examine polymorphisms in a spectrum of candidate genes that affect neurotransmitter systems influencing dopamine regulation or are thought to be associated with risk attitudes or impulsive disorders. Analysis of the genotyping data identified two single nucleotide polymorphisms (SNPs in the gene encoding the alpha 4 nicotine receptor (CHRNA4, rs4603829 and rs4522666 that are significantly associated with harm avoidance, a risk attitude measurement drawn from the psychology literature. Novelty seeking, another risk attitude measure from the psychology literature, is associated with several COMT (catechol-O-methyl transferase SNPs while economic risk attitude measures are associated with several VMAT2 (vesicular monoamine transporter SNPs, but the significance of these associations did not withstand statistical adjustment for multiple testing and requires larger cohorts. These exploratory results provide a starting point for understanding the genetic basis of risk attitudes by considering the range of methods available for measuring risk attitudes and by searching beyond the traditional direct focus on dopamine and serotonin receptor and transporter genes.

  8. 6-Bromohypaphorine from Marine Nudibranch Mollusk Hermissenda crassicornis is an Agonist of Human α7 Nicotinic Acetylcholine Receptor

    Directory of Open Access Journals (Sweden)

    Igor E. Kasheverov

    2015-03-01

    Full Text Available 6-Bromohypaphorine (6-BHP has been isolated from the marine sponges Pachymatisma johnstoni, Aplysina sp., and the tunicate Aplidium conicum, but data on its biological activity were not available. For the nudibranch mollusk Hermissenda crassicornis no endogenous compounds were known, and here we describe the isolation of 6-BHP from this mollusk and its effects on different nicotinic acetylcholine receptors (nAChR. Two-electrode voltage-clamp experiments on the chimeric α7 nAChR (built of chicken α7 ligand-binding and glycine receptor transmembrane domains or on rat α4β2 nAChR expressed in Xenopus oocytes revealed no action of 6-BHP. However, in radioligand analysis, 6-BHP competed with radioiodinated α-bungarotoxin for binding to human α7 nAChR expressed in GH4C1 cells (IC50 23 ± 1 μM, but showed no competition on muscle-type nAChR from Torpedo californica. In Ca2+-imaging experiments on the human α7 nAChR expressed in the Neuro2a cells, 6-BHP in the presence of PNU120596 behaved as an agonist (EC50 ~80 μM. To the best of our knowledge, 6-BHP is the first low-molecular weight compound from marine source which is an agonist of the nAChR subtype. This may have physiological importance because H. crassicornis, with its simple and tractable nervous system, is a convenient model system for studying the learning and memory processes.

  9. Functional analysis of Torpedo californica nicotinic acetylcholine receptors in multiple activation states by SSM-based electrophysiology.

    Science.gov (United States)

    Niessen, K V; Muschik, S; Langguth, F; Rappenglück, S; Seeger, T; Thiermann, H; Worek, F

    2016-04-15

    Organophosphorus compounds (OPC), i.e. nerve agents or pesticides, are highly toxic due to their strong inhibition potency against acetylcholinesterase (AChE). Inhibited AChE results in accumulation of acetylcholine in the synaptic cleft and thus the desensitisation of the nicotinic acetylcholine receptor (nAChR) in the postsynaptic membrane is provoked. Direct targeting of nAChR to reduce receptor desensitisation might be an alternative therapeutic approach. For drug discovery, functional properties of potent therapeutic candidates need to be investigated in addition to affinity properties. Solid supported membrane (SSM)-based electrophysiology is useful for functional characterisation of ligand-gated ion channels like nAChRs, as charge translocations via capacitive coupling of the supporting membrane can be measured. By varying the agonist (carbamoylcholine) concentration, different functional states of the nAChR were initiated. Using plasma membrane preparations obtained from Torpedo californica electric organ, functional properties of selected nAChR ligands and non-oxime bispyridinium compounds were investigated. Depending on overall-size, the bispyridinium compounds enhanced or inhibited cholinergic signals induced by 100 μM carbamoylcholine. Applying excessive concentrations of the agonist carbamoylcholine provoked desensitisation of the nAChRs, whereas addition of bispyridinium compounds bearing short alkyl linkers exhibited functional recovery of previously desensitised nAChRs. The results suggest that these non-oxime bispyridinium compounds possibly interacted with nAChR subtypes in a manner of a positive allosteric modulator (PAM). The described newly developed functional assay is a valuable tool for the assessment of functional properties of potential compounds such as nAChR modulating ligands, which might be a promising approach in the therapeutically treatment of OPC-poisonings. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. A novel inhibitor of α9α10 nicotinic acetylcholine receptors from Conus vexillum delineates a new conotoxin superfamily.

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    Sulan Luo

    Full Text Available Conotoxins (CTxs selectively target a range of ion channels and receptors, making them widely used tools for probing nervous system function. Conotoxins have been previously grouped into superfamilies according to signal sequence and into families based on their cysteine framework and biological target. Here we describe the cloning and characterization of a new conotoxin, from Conus vexillum, named αB-conotoxin VxXXIVA. The peptide does not belong to any previously described conotoxin superfamily and its arrangement of Cys residues is unique among conopeptides. Moreover, in contrast to previously characterized conopeptide toxins, which are expressed initially as prepropeptide precursors with a signal sequence, a ''pro'' region, and the toxin-encoding region, the precursor sequence of αB-VxXXIVA lacks a ''pro'' region. The predicted 40-residue mature peptide, which contains four Cys, was synthesized in each of the three possible disulfide arrangements. Investigation of the mechanism of action of αB-VxXXIVA revealed that the peptide is a nicotinic acetylcholine receptor (nAChR antagonist with greatest potency against the α9α10 subtype. (1H nuclear magnetic resonance (NMR spectra indicated that all three αB-VxXXIVA isomers were poorly structured in aqueous solution. This was consistent with circular dichroism (CD results which showed that the peptides were unstructured in buffer, but adopted partially helical conformations in aqueous trifluoroethanol (TFE solution. The α9α10 nAChR is an important target for the development of analgesics and cancer chemotherapeutics, and αB-VxXXIVA represents a novel ligand with which to probe the structure and function of this protein.

  11. Prorocentrolide-A from Cultured Prorocentrum lima Dinoflagellates Collected in Japan Blocks Sub-Types of Nicotinic Acetylcholine Receptors

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    Muriel Amar

    2018-02-01

    Full Text Available Prorocentrolides are members of the cyclic imine phycotoxins family. Their chemical structure includes a 26-membered carbo-macrocycle and a 28-membered macrocyclic lactone arranged around a hexahydroisoquinoline that incorporates the characteristic cyclic imine group. Six prorocentrolides are already known. However, their mode of action remains undetermined. The aim of the present work was to explore whether prorocentrolide A acts on nicotinic acetylcholine receptors (nAChRs, using competition-binding assays and electrophysiological techniques. Prorocentrolide-A displaced [125I]α-bungarotoxin binding to Torpedo membranes, expressing the muscle-type (α12β1γδ nAChR, and in HEK-293 cells, expressing the chimeric chick neuronal α7-5HT3 nAChR. Functional studies revealed that prorocentrolide-A had no agonist action on nAChRs, but inhibited ACh-induced currents in Xenopus oocytes that had incorporated the muscle-type α12β1γδ nAChR to their membranes, or that expressed the human α7 nAChR, as revealed by voltage-clamp recordings. Molecular docking calculations showed the absence of the characteristic hydrogen bond between the iminium group of prorocentrolide-A and the backbone carbonyl group of Trp147 in the receptor, explaining its weaker affinity as compared to all other cyclic imine toxins. In conclusion, this is the first study to show that prorocentrolide-A acts on both muscle and neuronal nAChRs, but with higher affinity on the muscle-type nAChR.

  12. In vivo functional analysis of the Drosophila melanogaster nicotinic acetylcholine receptor Dα6 using the insecticide spinosad.

    Science.gov (United States)

    Somers, Jason; Nguyen, Joseph; Lumb, Chris; Batterham, Phil; Perry, Trent

    2015-09-01

    The vinegar fly, Drosophila melanogaster, has been used to identify and manipulate insecticide resistance genes. The advancement of genome engineering technology and the increasing availability of pest genome sequences has increased the predictive and diagnostic capacity of the Drosophila model. The Drosophila model can be extended to investigate the basic biology of the interaction between insecticides and the proteins they target. Recently we have developed an in vivo system that permits the expression and study of key insecticide targets, the nicotinic acetylcholine receptors (nAChRs), in controlled genetic backgrounds. Here this system is used to study the interaction between the insecticide spinosad and a nAChR subunit, Dα6. Reciprocal chimeric subunits were created from Dα6 and Dα7, a subunit that does not respond to spinosad. Using the in vivo system, the Dα6/Dα7 chimeric subunits were tested for their capacity to respond to spinosad. Only the subunits containing the C-terminal region of Dα6 were able to respond to spinosad, thus confirming the importance this region for spinosad binding. A new incompletely dominant, spinosad resistance mechanism that may evolve in pest species is also examined. First generated using chemical mutagenesis, the Dα6(P146S) mutation was recreated using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system, the first use of this technology to introduce a resistant mutation into a controlled genetic background. Both alleles present with the same incompletely dominant, spinosad resistance phenotype, proving the P146S replacement to be the causal mutation. The proximity of the P146S mutation to the conserved Cys-loop indicates that it may impair the gating of the receptor. The results of this study enhance the understanding of nAChR structure:function relationships. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  13. The α7 nicotinic acetylcholine receptor: A mediator of pathogenesis and therapeutic target in autism spectrum disorders and Down syndrome.

    Science.gov (United States)

    Deutsch, Stephen I; Burket, Jessica A; Urbano, Maria R; Benson, Andrew D

    2015-10-15

    Currently, there are no medications that target core deficits of social communication and restrictive, repetitive patterns of behavior in persons with autism spectrum disorders (ASDs). Adults with Down syndrome (DS) display a progressive worsening of adaptive functioning, which is associated with Alzheimer's disease (AD)-like histopathological changes in brain. Similar to persons with ASDs, there are no effective medication strategies to prevent or retard the progressive worsening of adaptive functions in adults with DS. Data suggest that the α7-subunit containing nicotinic acetylcholine receptor (α7nAChR) is implicated in the pathophysiology and serves as a promising therapeutic target of these disorders. In DS, production of the amyloidogenic Aβ1-42 peptide is increased and binds to the α7nAChR or the lipid milieu associated with this receptor, causing a cascade that results in cytotoxicity and deposition of amyloid plaques. Independently of their ability to inhibit the complexing of Aβ1-42 with the α7nAChR, α7nAChR agonists and positive allosteric modulators (PAMs) also possess procognitive and neuroprotective effects in relevant in vivo and in vitro models. The procognitive and neuroprotective effects of α7nAChR agonist interventions may be due, at least in part, to stimulation of the PI3K/Akt signaling cascade, cross-talk with the Wnt/β-catenin signaling cascade and both transcriptional and non-transcriptional effects of β-catenin, and effects of transiently increased intraneuronal concentrations of Ca(2+) on metabolism and the membrane potential. Importantly, α7nAChR PAMs are particularly attractive medication candidates because they lack intrinsic efficacy and act only when and where endogenous acetylcholine is released or choline is generated. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Molecular characterization and expression profiles of nicotinic acetylcholine receptors in the rice striped stem borer, Chilo suppressalis (Lepidoptera: Crambidae).

    Science.gov (United States)

    Xu, Gang; Wu, Shun-Fan; Teng, Zi-Wen; Yao, Hong-Wei; Fang, Qi; Huang, Jia; Ye, Gong-Yin

    2017-06-01

    Nicotinic acetylcholine receptors (nAChRs) are members of the cys-loop ligand-gated ion channel (cysLGIC) superfamily, mediating fast synaptic cholinergic transmission in the central nervous system in insects. Insect nAChRs are the molecular targets of economically important insecticides, such as neonicotinoids and spinosad. Identification and characterization of the nAChR gene family in the rice striped stem borer, Chilo suppressalis, could provide beneficial information about this important receptor gene family and contribute to the investigation of the molecular modes of insecticide action and resistance for current and future chemical control strategies. We searched our C. suppressalis transcriptome database using Bombyx mori nAChR sequences in local BLAST searches and obtained the putative nAChR subunit complementary DNAs (cDNAs) via reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends methods. Similar to B. mori, C. suppressalis possesses 12 nAChR subunits, including nine α-type and three β-type subunits. Quantitative RT-PCR analysis revealed the expression profiles of the nAChR subunits in various tissues, including the brain, subesophageal ganglion, thoracic ganglion, abdominal ganglion, hemocytes, fat body, foregut, midgut, hindgut and Malpighian tubules. Developmental expression analyses showed clear differential expression of nAChR subunits throughout the C. suppressalis life cycle. The identification of nAChR subunits in this study will provide a foundation for investigating the diverse roles played by nAChRs in C. suppressalis and for exploring specific target sites for chemicals that control agricultural pests while sparing beneficial species. ©2016 The Authors Insect Science published by John Wiley & Sons Australia, Ltd on behalf of Institute of Zoology, Chinese Academy of Sciences.

  15. Unraveling the high- and low-sensitivity agonist responses of nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Harpsøe, Kasper; Ahring, Philip K; Christensen, Jeppe K

    2011-01-01

    for the observation of two distinct agonist sensitivities. Using different expression ratios of mammalian a4 and ß2 subunits and concatenated constructs, we demonstrate that a biphasic response is an intrinsic functional property of the (a4)(3)(ß2)(2) receptor. In addition to two high-sensitivity sites at a4ß2...

  16. Cellular and synaptic mechanisms of nicotine addiction

    NARCIS (Netherlands)

    Mansvelder, H.D.; McGehee, D.S.

    2002-01-01

    The tragic health effects of nicotine addiction highlight the importance of investigating the cellular mechanisms of this complex behavioral phenomenon. The chain of cause and effect of nicotine addiction starts with the interaction of this tobacco alkaloid with nicotinic acetylcholine receptors

  17. Dual Modulators of GABA-A and Alpha7 Nicotinic Receptors for Treating Autism

    Science.gov (United States)

    2014-08-01

    figure 3). The effect was dose- dependent with no significant effect observed at a dose of 0.3 mg/kg i.p. (data not shown). 8...Interestingly recent studies with the benzodiazepine agonist clonazepam, a non-selective GABAA receptor PAM, resulted in a bell-shaped dose response...These dose- dependence studies are underway and will not be complete until August 2014 because of changes in baseline BTBR behavior described below

  18. The nicotinic acetylcholine receptors of the parasitic nematode Ascaris suum: formation of two distinct drug targets by varying the relative expression levels of two subunits.

    Science.gov (United States)

    Williamson, Sally M; Robertson, Alan P; Brown, Laurence; Williams, Tracey; Woods, Debra J; Martin, Richard J; Sattelle, David B; Wolstenholme, Adrian J

    2009-07-01

    Parasitic nematodes are of medical and veterinary importance, adversely affecting human health and animal welfare. Ascaris suum is a gastrointestinal parasite of pigs; in addition to its veterinary significance it is a good model of the human parasite Ascaris lumbricoides, estimated to infect approximately 1.4 billion people globally. Anthelmintic drugs are essential to control nematode parasites, and nicotinic acetylcholine receptors (nAChRs) on nerve and muscle are the targets of cholinergic anthelmintics such as levamisole and pyrantel. Previous genetic analyses of nematode nAChRs have been confined to Caenorhabditis elegans, which is phylogenetically distinct from Ascaris spp. and many other important parasites. Here we report the cloning and expression of two nAChR subunit cDNAs from A. suum. The subunits are very similar in sequence to C. elegans UNC-29 and UNC-38, are expressed on muscle cells and can be expressed robustly in Xenopus oocytes to form acetylcholine-, nicotine-, levamisole- and pyrantel-sensitive channels. We also demonstrate that changing the stoichiometry of the receptor by injecting different ratios of the subunit cRNAs can reproduce two of the three pharmacological subtypes of nAChR present in A. suum muscle cells. When the ratio was 5:1 (Asu-unc-38ratioAsu-unc-29), nicotine was a full agonist and levamisole was a partial agonist, and oocytes responded to oxantel, but not pyrantel. At the reverse ratio (1:5 Asu-unc-38ratioAsu-unc-29), levamisole was a full agonist and nicotine was a partial agonist, and the oocytes responded to pyrantel, but not oxantel. These results represent the first in vitro expression of any parasitic nicotinic receptor and show that their properties are substantially different from those of C. elegans. The results also show that changing the expression level of a single receptor subunit dramatically altered the efficacy of some anthelmintic drugs. In vitro expression of these subunits may permit the development of

  19. The nicotinic acetylcholine receptors of the parasitic nematode Ascaris suum: formation of two distinct drug targets by varying the relative expression levels of two subunits.

    Directory of Open Access Journals (Sweden)

    Sally M Williamson

    2009-07-01

    Full Text Available Parasitic nematodes are of medical and veterinary importance, adversely affecting human health and animal welfare. Ascaris suum is a gastrointestinal parasite of pigs; in addition to its veterinary significance it is a good model of the human parasite Ascaris lumbricoides, estimated to infect approximately 1.4 billion people globally. Anthelmintic drugs are essential to control nematode parasites, and nicotinic acetylcholine receptors (nAChRs on nerve and muscle are the targets of cholinergic anthelmintics such as levamisole and pyrantel. Previous genetic analyses of nematode nAChRs have been confined to Caenorhabditis elegans, which is phylogenetically distinct from Ascaris spp. and many other important parasites. Here we report the cloning and expression of two nAChR subunit cDNAs from A. suum. The subunits are very similar in sequence to C. elegans UNC-29 and UNC-38, are expressed on muscle cells and can be expressed robustly in Xenopus oocytes to form acetylcholine-, nicotine-, levamisole- and pyrantel-sensitive channels. We also demonstrate that changing the stoichiometry of the receptor by injecting different ratios of the subunit cRNAs can reproduce two of the three pharmacological subtypes of nAChR present in A. suum muscle cells. When the ratio was 5:1 (Asu-unc-38ratioAsu-unc-29, nicotine was a full agonist and levamisole was a partial agonist, and oocytes responded to oxantel, but not pyrantel. At the reverse ratio (1:5 Asu-unc-38ratioAsu-unc-29, levamisole was a full agonist and nicotine was a partial agonist, and the oocytes responded to pyrantel, but not oxantel. These results represent the first in vitro expression of any parasitic nicotinic receptor and show that their properties are substantially different from those of C. elegans. The results also show that changing the expression level of a single receptor subunit dramatically altered the efficacy of some anthelmintic drugs. In vitro expression of these subunits may permit the

  20. Effects of Menthol on Nicotine Pharmacokinetic, Pharmacology and Dependence in Mice.

    Directory of Open Access Journals (Sweden)

    Shakir D Alsharari

    Full Text Available Although menthol, a common flavoring additive to cigarettes, has been found to impact the addictive properties of nicotine cigarettes in smokers little is known about its pharmacological and molecular actions in the brain. Studies were undertaken to examine whether the systemic administration of menthol would modulate nicotine pharmacokinetics, acute pharmacological effects (antinociception and hypothermia and withdrawal in male ICR mice. In addition, we examined changes in the brain levels of nicotinic receptors of rodents exposed to nicotine and menthol. Administration of i.p. menthol significantly decreased nicotine's clearance (2-fold decrease and increased its AUC compared to i.p. vehicle treatment. In addition, menthol pretreatment prolonged the duration of nicotine-induced antinociception and hypothermia (2.5 mg/kg, s.c. for periods up to 180 min post-nicotine administration. Repeated administration of menthol with nicotine increased the intensity of mecamylamine-precipitated withdrawal signs in mice exposed chronically to nicotine. The potentiation of withdrawal intensity by menthol was accompanied by a significant increase in nicotine plasma levels in these mice. Western blot analyses of α4 and β2 nAChR subunit expression suggests that chronic menthol impacts the levels and distribution of these nicotinic subunits in various brain regions. In particular, co-administration of menthol and nicotine appears to promote significant increase in β2 and α4 nAChR subunit expression in the hippocampus, prefrontal cortex and striatum of mice. Surprisingly, chronic injections of menthol alone to mice caused an upregulation of β2 and α4 nAChR subunit levels in these brain regions. Because the addition of menthol to tobacco products has been suggested to augment their addictive potential, the current findings reveal several new pharmacological molecular adaptations that may contribute to its unique addictive profile.

  1. Effects of Menthol on Nicotine Pharmacokinetic, Pharmacology and Dependence in Mice.

    Science.gov (United States)

    Alsharari, Shakir D; King, Justin R; Nordman, Jacob C; Muldoon, Pretal P; Jackson, Asti; Zhu, Andy Z X; Tyndale, Rachel F; Kabbani, Nadine; Damaj, M Imad

    2015-01-01

    Although menthol, a common flavoring additive to cigarettes, has been found to impact the addictive properties of nicotine cigarettes in smokers little is known about its pharmacological and molecular actions in the brain. Studies were undertaken to examine whether the systemic administration of menthol would modulate nicotine pharmacokinetics, acute pharmacological effects (antinociception and hypothermia) and withdrawal in male ICR mice. In addition, we examined changes in the brain levels of nicotinic receptors of rodents exposed to nicotine and menthol. Administration of i.p. menthol significantly decreased nicotine's clearance (2-fold decrease) and increased its AUC compared to i.p. vehicle treatment. In addition, menthol pretreatment prolonged the duration of nicotine-induced antinociception and hypothermia (2.5 mg/kg, s.c.) for periods up to 180 min post-nicotine administration. Repeated administration of menthol with nicotine increased the intensity of mecamylamine-precipitated withdrawal signs in mice exposed chronically to nicotine. The potentiation of withdrawal intensity by menthol was accompanied by a significant increase in nicotine plasma levels in these mice. Western blot analyses of α4 and β2 nAChR subunit expression suggests that chronic menthol impacts the levels and distribution of these nicotinic subunits in various brain regions. In particular, co-administration of menthol and nicotine appears to promote significant increase in β2 and α4 nAChR subunit expression in the hippocampus, prefrontal cortex and striatum of mice. Surprisingly, chronic injections of menthol alone to mice caused an upregulation of β2 and α4 nAChR subunit levels in these brain regions. Because the addition of menthol to tobacco products has been suggested to augment their addictive potential, the current findings reveal several new pharmacological molecular adaptations that may contribute to its unique addictive profile.

  2. Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis

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    Qiang Liu

    2017-09-01

    Full Text Available Previous studies have demonstrated immunosuppressive and anti-inflammatory effects of nicotine, including in the experimental autoimmune encephalomyelitis (EAE model in mice of some forms of multiple sclerosis (MS. Other studies using knock-out (KO mice have implicated nicotinic acetylcholine (ACh receptors containing α7, α9, or β2 subunits (α7*-, α9*- or β2*-nAChR in different, disease-exacerbating or disease-ameliorating processes. These outcomes are in harmony with gene expression analyses showing nAChR subunit mRNA in many classes of immune system cell types. Consistent with influences on disease status, predictable effects of nAChR subunit (and subtype KO, or of nicotine exposure, are seen on immune cell numbers and distribution and on cytokine levels or other markers of immunity, inflammation, demyelination, and axonal degradation. Providing support for our hypotheses about distinctive roles for nAChR subtypes in EAE, here we have used direct and adoptive EAE induction and a nAChR subunit gene double knock-out (DKO strategy. Immune cell expression of nAChR α9 subunits as protein is demonstrated by immunostaining of isolated CD4+, CD8+, CD11b+ and CD11c+ cells from wild-type (WT mice, but not in cells from nAChR α9 subunit KO animals. Nicotine exposure is protective against directly-induced EAE in WT or α7/α9 DKO animals relative to effects seen in WT/vehicle-treated mice, but, remarkably, EAE is exacerbated in vehicle-treated α7/α9 DKO mice. Brain lesion volume and intra-cranial inflammatory activity similarly are higher in DKO/vehicle than in WT/vehicle-treated animals, although nicotine’s protective effects are seen in each instance. By contrast, in adoptive transfer studies, disease severity is attenuated and disease onset is delayed in recipients of splenocytes from WT animals treated with nicotine rather than with vehicle. Moreover, protection as seen in nicotine-treated WT animals is the same in recipients of

  3. Desnitro-imidacloprid activates the extracellular signal-regulated kinase cascade via the nicotinic receptor and intracellular calcium mobilization in N1E-115 cells.

    Science.gov (United States)

    Tomizawa, Motohiro; Casida, John E

    2002-11-01

    Imidacloprid (IMI) is the principal neonicotinoid (the only major new class of synthetic insecticides of the past three decades). The excellent safety profile of IMI is not shared with a metabolite, desnitro-IMI (DNIMI), which displays high toxicity to mammals associated with agonist action at the alpha4beta2 nicotinic acetylcholine receptor (nAChR) in brain. This study examines the hypothesis that IMI, DNIMI, and (-)-nicotine activate the extracellular signal-regulated kinase (ERK) cascade via primary interaction with the alpha4beta2 nAChR in mouse neuroblastoma N1E-115 cells. These three nicotinic agonists induce phosphorylation of ERK (p44/p42) in a concentration-dependent manner with an optimal incubation period of 30 min. DNIMI (1 microM)-induced ERK activation is blocked by nicotinic antagonist mecamylamine but not by alpha-bungarotoxin and muscarinic antagonist atropine. This activation is prevented by intracellular Ca(2+) chelator BAPTA-AM but not by removal of external Ca(2+) using EGTA and Ca(2+)-free medium. 2-Aminoethoxy-diphenylborate, a blocker for inositol 1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release from intracellular stores, inhibits DNIMI-induced ERK activation but a high level of ryanodine (to block ryanodine receptor-mediated Ca(2+) release) does not. The inhibitor U-73122 for phospholipase C (to suppress IP(3) production) prevents ERK activation evoked by DNIMI. Inhibitors for protein kinase C (PKC) (GF109203X) and ERK kinase (PD98059) block this activation whereas an inhibitor (H-89) for cyclic AMP-dependent protein kinase does not. Thus, neonicotinoids activate the ERK cascade triggered by primary action at the alpha4beta2 nAChR with an involvement of intracellular Ca(2+) mobilization possibly mediated by IP(3). It is further suggested that intracellular Ca(2+) activates a sequential pathway from PKC to ERK.

  4. Nicotinic receptors modulate the onset of reactive oxygen species production and mitochondrial dysfunction evoked by glutamate uptake block in the rat hypoglossal nucleus.

    Science.gov (United States)

    Tortora, Maria; Corsini, Silvia; Nistri, Andrea

    2017-02-03

    In several neurodegenerative diseases, glutamate-mediated excitotoxicity is considered to be a major process to initiate cell degeneration. Indeed, subsequent to excessive glutamate receptor stimulation, reactive oxygen species (ROS) generation and mitochondrial dysfunction are regarded as two major gateways leading to neuron death. These processes are mimicked in an in vitro model of rat brainstem slice when excitotoxicity is induced by DL-threo-β-benzyloxyaspartate (TBOA), a specific glutamate-uptake blocker that increases extracellular glutamate. Our recent study has demonstrated that brainstem hypoglossal motoneurons, which are very vulnerable to this damage, were neuroprotected from excitotoxicity with nicotine application through the activation of nicotinic acetylcholine receptors (nAChRs) and subsequent inhibition of ROS and mitochondrial dysfunction. The present study examined if endogenous cholinergic activity exerted any protective effect in this pathophysiological model and how ROS production (estimated with rhodamine fluorescence) and mitochondrial dysfunction (measured as methyltetrazolium reduction) were time-related during the early phase of excitotoxicity (0-4h). nAChR antagonists did not modify TBOA-evoked ROS production (that was nearly doubled over control) or mitochondrial impairment (25% decline), suggesting that intrinsic nAChR activity was insufficient to contrast excitotoxicity and needed further stimulation with nicotine to become effective. ROS production always preceded mitochondrial dysfunction by about 2h. Nicotine prevented both ROS production and mitochondrial metabolic depression with a delayed action that alluded to a complex chain of events targeting these two lesional processes. The present data indicate a relatively wide time frame during which strong nAChR activation can arrest a runaway neurotoxic process leading to cell death. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. Snake alpha-neurotoxin binding site on the Egyptian cobra (Naja haje) nicotinic acetylcholine receptor Is conserved.

    Science.gov (United States)

    Takacs, Z; Wilhelmsen, K C; Sorota, S

    2001-09-01

    Evolutionary success requires that animal venoms are targeted against phylogenetically conserved molecular structures of fundamental physiological processes. Species producing venoms must be resistant to their action. Venoms of Elapidae snakes (e.g., cobras, kraits) contain alpha-neurotoxins, represented by alpha-bungarotoxin (alpha-BTX) targeted against the nicotinic acetylcholine receptor (nAChR) of the neuromuscular junction. The model which presumes that cobras (Naja spp., Elapidae) have lost their binding site for conspecific alpha-neurotoxins because of the unique amino acid substitutions in their nAChR polypeptide backbone per se is incompatible with the evolutionary theory that (1) the molecular motifs forming the alpha-neurotoxin target site on the nAChR are fundamental for receptor structure and/or function, and (2) the alpha-neurotoxin target site is conserved among Chordata lineages. To test the hypothesis that the alpha-neurotoxin binding site is conserved in Elapidae snakes and to identify the mechanism of resistance against conspecific alpha-neurotoxins, we cloned the ligand binding domain of the Egyptian cobra (Naja haje) nAChR alpha subunit. When expressed as part of a functional Naja/mouse chimeric nAChR in Xenopus oocytes, this domain confers resistance against alpha-BTX but does not alter responses induced by the natural ligand acetylcholine. Further mutational analysis of the Naja/mouse nAChR demonstrated that an N-glycosylation signal in the ligand binding domain that is unique to N. haje is responsible for alpha-BTX resistance. However, when the N-glycosylation signal is eliminated, the nAChR containing the N. haje sequence is inhibited by alpha-BTX with a potency that is comparable to that in mammals. We conclude that the binding site for conspecific alpha-neurotoxin in Elapidae snakes is conserved in the nAChR ligand binding domain polypeptide backbone per se. This conclusion supports the hypothesis that animal toxins are targeted against

  6. An experimental study on (131)I-CHIBA-1001: a radioligand for α7 nicotinic acetylcholine receptors.

    Science.gov (United States)

    Yin, Lei; Zhao, Qian; Li, Ling; Zhang, Su Lei; Chen, Xue Qi; Ma, Chao; Kang, Lei; Liu, Meng; Zhang, Chun Li; Yan, Ping; Wang, Rong Fu

    2013-01-01

    The α7 nicotinic acetylcholine receptors (nAChRs) play a vital role in the pathophysiology of neuropsychiatric diseases such as Alzheimer's disease and depression. However, there is currently no suitable positron emission tomography (PET) or Single-Photon Emission Computed Tomography (SPECT) radioligands for imaging α7 nAChRs in brain. Here our aim is to radiosynthesize a novel SPECT radioligand (131)I-CHIBA-1001 for whole body biodistribution study and in vivo imaging of α7 nAChRs in brain. (131)I-CHIBA-1001 was radiosynthesized by chloramine-T method. Different conditions of reaction time and temperature were tested to get a better radiolabeling yield. Radiolabeling yield and radiochemical purities of (131)I-CHIBA-1001 were analyzed by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) system. Whole body biodistribution study was performed at different time points post injection of (131)I-CHIBA-1001 in KM mice. Monkey subject was used for in vivo SPECT imaging in brain. The radiolabeling yield of (131)I-CHIBA-1001 reached 96% within 1.5∼2.0 h at 90∼95°C. The radiochemical purity reached more than 99% after HPLC purification. (131)I-CHIBA-1001 was highly stable in saline and fresh human serum in room temperature and 37°C separately. The biodistribution data of brain at 15, 30, and 60 min were 11.05±1.04%ID/g, 8.8±0.04%ID/g and 6.28±1.13%ID/g, respectively. In experimental SPECT imaging, the distribution of radioactivity in the brain regions was paralleled with the distribution of α7 nAChRs in the monkey brain. Moreover, in the blocking SPECT imaging study, the selective α7 nAChR agonist SSR180711 blocked the radioactive uptake in the brain successfully. The CHIBA-1001 can be successfully radiolabeled with (131)I using the chloramine-T method. (131)I-CHIBA-1001 can successfully accumulate in the monkey brain and image the α7 acetylcholine receptors. (131)I-CHIBA-1001 can be a candidate for imagingα7 acetylcholine

  7. An experimental study on (131I-CHIBA-1001: a radioligand for α7 nicotinic acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Lei Yin

    Full Text Available OBJECTIVE: The α7 nicotinic acetylcholine receptors (nAChRs play a vital role in the pathophysiology of neuropsychiatric diseases such as Alzheimer's disease and depression. However, there is currently no suitable positron emission tomography (PET or Single-Photon Emission Computed Tomography (SPECT radioligands for imaging α7 nAChRs in brain. Here our aim is to radiosynthesize a novel SPECT radioligand (131I-CHIBA-1001 for whole body biodistribution study and in vivo imaging of α7 nAChRs in brain. METHOD: (131I-CHIBA-1001 was radiosynthesized by chloramine-T method. Different conditions of reaction time and temperature were tested to get a better radiolabeling yield. Radiolabeling yield and radiochemical purities of (131I-CHIBA-1001 were analyzed by thin layer chromatography (TLC and high-performance liquid chromatography (HPLC system. Whole body biodistribution study was performed at different time points post injection of (131I-CHIBA-1001 in KM mice. Monkey subject was used for in vivo SPECT imaging in brain. RESULT: The radiolabeling yield of (131I-CHIBA-1001 reached 96% within 1.5∼2.0 h at 90∼95°C. The radiochemical purity reached more than 99% after HPLC purification. (131I-CHIBA-1001 was highly stable in saline and fresh human serum in room temperature and 37°C separately. The biodistribution data of brain at 15, 30, and 60 min were 11.05±1.04%ID/g, 8.8±0.04%ID/g and 6.28±1.13%ID/g, respectively. In experimental SPECT imaging, the distribution of radioactivity in the brain regions was paralleled with the distribution of α7 nAChRs in the monkey brain. Moreover, in the blocking SPECT imaging study, the selective α7 nAChR agonist SSR180711 blocked the radioactive uptake in the brain successfully. CONCLUSION: The CHIBA-1001 can be successfully radiolabeled with (131I using the chloramine-T method. (131I-CHIBA-1001 can successfully accumulate in the monkey brain and image the α7 acetylcholine receptors. (131I-CHIBA-1001 can be a

  8. Nicotine stimulates secretion of corticosterone via both CRH and AVP receptors

    OpenAIRE

    Lutfy, Kabirullah; Aimiuwu, Otaren; Mangubat, Michael; Shin, Chang-Sung; Nerio, Namiko; Gomez, Richard; Liu, Yanjun; Friedman, Theodore C.

    2012-01-01

    Corticosterone–releasing hormone (CRH) and arginine vasopressin (AVP) are crucial components of the hypothalamic-pituitary-adrenal (HPA) axis that stimulates the release of adrenocorticotropic hormone (ACTH) from the pituitary and mediate the stress response. CRH binds to two subtypes of CRH receptors (CRH-R1 and CRH-R2) that are present in both central and peripheral tissues. We used the CRH-R1 specific antagonist, antalarmin (ANT), the CRH-R1 and CRH-R2 peptide antagonist, astressin (AST), ...

  9. Rational design of a-conotoxin analogues targeting a7 nicotinic acetylcholine receptors

    DEFF Research Database (Denmark)

    Armishaw, Christopher; Jensen, Anders Asbjørn; Balle, Thomas

    2009-01-01

    BPs) that share significant sequence homology with the amino-terminal domains of the nAChRs. alpha-Conotoxins which are isolated from the venom of carnivorous marine snails selectively inhibit the signalling of neuronal nAChR subtypes. Co-crystal structures of alpha-conotoxins in complex with AChBP show...... reduced antagonistic activities, analogues with aromatic and hydrophobic substituents in the Pro6 position exhibit moderate activity at the receptor. Interestingly, introduction of a 5-(R)-Phenyl substituent at Pro6 in alpha-conotoxin ImI gives rise to a conotoxin analogue with a significantly higher...

  10. Difference in Perseverative Errors during a Visual Attention Task with Auditory Distractors in Alpha-9 Nicotinic Receptor Subunit Wild Type and Knock-Out Mice

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    Pascal Jorratt

    2017-11-01

    Full Text Available The auditory efferent system is a neural network that originates in the auditory cortex and projects to the cochlear receptor through olivocochlear (OC neurons. Medial OC neurons make cholinergic synapses with outer hair cells (OHCs through nicotinic receptors constituted by α9 and α10 subunits. One of the physiological functions of the α9 nicotinic receptor subunit (α9-nAChR is the suppression of auditory distractors during selective attention to visual stimuli. In a recent study we demonstrated that the behavioral performance of alpha-9 nicotinic receptor knock-out (KO mice is altered during selective attention to visual stimuli with auditory distractors since they made less correct responses and more omissions than wild type (WT mice. As the inhibition of the behavioral responses to irrelevant stimuli is an important mechanism of the selective attention processes, behavioral errors are relevant measures that can reflect altered inhibitory control. Errors produced during a cued attention task can be classified as premature, target and perseverative errors. Perseverative responses can be considered as an inability to inhibit the repetition of an action already planned, while premature responses can be considered as an index of the ability to wait or retain an action. Here, we studied premature, target and perseverative errors during a visual attention task with auditory distractors in WT and KO mice. We found that α9-KO mice make fewer perseverative errors with longer latencies than WT mice in the presence of auditory distractors. In addition, although we found no significant difference in the number of target error between genotypes, KO mice made more short-latency target errors than WT mice during the presentation of auditory distractors. The fewer perseverative error made by α9-KO mice could be explained by a reduced motivation for reward and an increased impulsivity during decision making with auditory distraction in KO mice.

  11. Expression of vitamin D receptor (VDR) decreases during progression of pigmented skin lesions

    Science.gov (United States)

    Brożyna, Anna A.; Jozwicki, Wojciech; Janjetovic, Zorica; Slominski, Andrzej T.

    2010-01-01

    1,25-dihydroxyvitamin D3 affects proliferation, differentiation and apoptosis and protects DNA against oxidative damage with a net tumorostatic and anticancerogenic effects. It acts through a specific nuclear receptor that is widely distributed through the body. Although a beneficial role of vitamin D in melanoma patients has been suggested, there is a lack of information on the changes in the expression pattern of vitamin D receptor during progression of pigmented lesions. Using immunohistochemistry, we analyzed expression of vitamin D receptor in 140 samples obtained form 82 patients, including 25 benign nevi, 70 primary cutaneous melanomas, 35 metastases, 5 re-excisions, and 5 normal skin biopsies. The strongest expression was observed in normal skin that significantly decreased in melanocytic proliferations with the following order of expression: normal skin > melanocytic nevi > melanomas = metastases. The vitamin D receptor expression in skin surrounding nevi and melanoma was also significantly reduced as compared to normal skin. Tumor-infiltrating and lymph node lymphocytes retained high levels of vitamin D receptor. There was negative correlation between tumor progression and vitamin D receptor expression with a remarkable decrease of the immunoreactivity in nuclei of melanoma cells at vertical versus radial growth phases, and with metastatic melanomas showing the lowest cytoplasmic receptor staining. Furthermore, lack of the receptor expression in primary melanomas and metastases was related to shorter overall patients’ survival. In addition, the receptor expression decreased in melanized melanoma cells in comparison to amelanotic or poorly pigmented cells. Therefore, we propose that reduction or absence of vitamin D receptor is linked to progression of melanocytic lesions, that its lack affects survival of melanoma patients, and that melanogenesis can attenuate the receptor expression. In conclusion, changes in vitamin D receptor expression pattern can

  12. Expression of vitamin D receptor decreases during progression of pigmented skin lesions.

    Science.gov (United States)

    Brożyna, Anna A; Jozwicki, Wojciech; Janjetovic, Zorica; Slominski, Andrzej T

    2011-05-01

    1,25-dihydroxyvitamin D3 affects proliferation, differentiation, and apoptosis and protects DNA against oxidative damage with a net tumorostatic and anticarcinogenic effect. It acts through a specific nuclear receptor that is widely distributed through the body. Although a beneficial role of vitamin D in melanoma patients has been suggested, there is lack of information on the changes in the expression pattern of vitamin D receptor during progression of pigmented lesions. Using immunohistochemistry, we analyzed the expression of vitamin D receptor in 140 samples obtained form 82 patients, including 25 benign nevi, 70 primary cutaneous melanomas, 35 metastases, 5 re-excisions, and 5 normal skin biopsies. The strongest expression was observed in normal skin that significantly decreased in melanocytic proliferations with the following order of expression: normal skin > melanocytic nevi > melanomas = metastases. The vitamin D receptor expression in skin surrounding nevi and melanoma was also significantly reduced as compared to normal skin. Tumor-infiltrating and lymph node lymphocytes retained high levels of vitamin D receptor. There was negative correlation between tumor progression and vitamin D receptor expression with a remarkable decrease of the immunoreactivity in nuclei of melanoma cells at vertical versus radial growth phases and with metastatic melanomas showing the lowest cytoplasmic receptor staining. Furthermore, lack of the receptor expression in primary melanomas and metastases was related to shorter overall patients' survival. In addition, the receptor expression decreased in melanized melanoma cells in comparison to amelanotic or poorly pigmented cells. Therefore, we propose that reduction or absence of vitamin D receptor is linked to progression of melanocytic lesions, that its lack affects survival of melanoma patients, and that melanogenesis can attenuate receptor expression. In conclusion, changes in vitamin D receptor expression pattern can serve

  13. Decreased Insulin Receptors but Normal Glucose Metabolism in Duchenne Muscular Dystrophy

    Science.gov (United States)

    de Pirro, Roberto; Lauro, Renato; Testa, Ivano; Ferretti, Ginofabrizio; de Martinis, Carlo; Dellantonio, Renzo

    1982-04-01

    Compared to matched controls, 17 patients with Duchenne muscular dystrophy showed decreased insulin binding to monocytes due to decreased receptor concentration. These patients showed no signs of altered glucose metabolism and retrospective analysis of the clinical records of a further 56 such patients revealed no modification in carbohydrate metabolism. These data suggest that reduced insulin receptor number does not produce overt modifications of glucose metabolism in Duchenne muscular dystrophy.

  14. Contextual renewal of nicotine seeking in rats and its suppression by the cannabinoid-1 receptor antagonist Rimonabant (SR141716A)

    NARCIS (Netherlands)

    Diergaarde, L.; de Vries, W.; Raaso, H.; Schoffelmeer, A.N.M.; de Vries, T.J.

    2008-01-01

    Nicotine-associated paraphernalia such as cigarettes and ashtrays are potent smoking relapse triggers. In addition to these discrete cues, environmental contexts previously associated with smoking elicit strong cigarette craving, indicating that contextual stimuli also contribute to high smoking

  15. Nicotinic potentiation of frog retinotectal transmission in tectum layer F by α3β2, α4β2, α2β4, α6β2, or α7 acetylcholine receptor subtypes

    Directory of Open Access Journals (Sweden)

    Armuntas Baginskas

    2015-01-01

    Conclusions: The tonic and phasic potentiation of the retinotectal transmission in the tectum layer F were not mediated by the receptors of α3β2, α4β2, α2β4, α6β2 or α7 subtype. The results suggest that presynaptic nicotinic acetylcholine receptors of the frog optic fibers are different from those of the mammalian optic fibers.

  16. Synthesis and evaluation of [{sup 125}I]I-TSA as a brain nicotinic acetylcholine receptor {alpha}{sub 7} subtype imaging agent

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Mikako [Laboratory of Genome Bio-Photonics, Photon Medical Research Center, Hamamatsu Medical University, Hamamatsu 431-3192 (Japan); Tatsumi, Ryo [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Fujio, Masakazu [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Katayama, Jiro [Pharmaceuticals Research Unit, Research and Development Division, Mitsubishi Pharma Corporation, Yokohama 227-0033 (Japan); Magata, Yasuhiro [Laboratory of Genome Bio-Photonics, Photon Medical Research Center, Hamamatsu Medical University, Hamamatsu 431-3192 (Japan)]. E-mail: magata@hama-med.ac.jp

    2006-04-15

    Introduction: Some in vitro investigations have suggested that the nicotinic acetylcholine receptor (nAChR) {alpha}{sub 7} subtype is implicated in Alzheimer's disease, schizophrenia and others. Recently, we developed (R)-3'-(5-bromothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'-[1',3'] oxazolidin]-2'-one (Br-TSA), which has a high affinity and selectivity for {alpha}{sub 7} nAChRs. Therefore we synthesized (R)-3'-(5-[{sup 125}I]iodothiophen-2-yl)spiro[1-azabicyclo[2.2.2]octane-3,5'- [1',3']oxazolidin]-2'-one ([{sup 125}I]I-TSA) and evaluated its potential for the in vivo detection of {alpha}{sub 7} nAChR in brain. Methods: In vitro binding affinity of I-TSA was measured in rat brain homogenates. Radioiodination was accomplished by a Br-I exchange reaction. Biodistribution studies were undertaken in mice by tail vein injection of [{sup 125}I]I-TSA. In vivo receptor blocking studies were carried out by treating mice with methyllycaconitine (MLA; 5 nmol/5 {mu}l, i.c.v.) or nonradioactive I-TSA (50 {mu}mol/kg, i.v.). Results: I-TSA exhibited a high affinity and selectivity for the {alpha}{sub 7} nAChR (K {sub i} for {alpha}{sub 7} nAChR=0.54 nM). Initial uptake in the brain was high (4.42 %dose/g at 5 min), and the clearance of radioactivity was relatively slow in the hippocampus ({alpha}{sub 7} nAChR-rich region) and was rather rapid in the cerebellum ({alpha}{sub 7} nAChR poor region). The hippocampus to cerebellum uptake ratio was 0.9 at 5 min postinjection, but it was increased to 1.8 at 60 min postinjection. Although the effect was not statistically significant, administration of I-TSA and MLA decreased the accumulation of radioactivity in hippocampus. Conclusion: Despite its high affinity and selectivity, [{sup 125}I]I-TSA does not appear to be a suitable tracer for in vivo {alpha}{sub 7} nAChR receptor imaging studies due to its high nonspecific binding. Further structural optimization is needed.

  17. Nicotinic acid receptor GPR109A is down-regulated in human macrophage-derived foam cells.

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    Joshua T Chai

    Full Text Available Nicotinic acid (NA regresses atherosclerosis in human imaging studies and reduces atherosclerosis in mice, mediated by myeloid cells, independent of lipoproteins. Since GPR109A is expressed by human monocytes, we hypothesized that NA may drive cholesterol efflux from foam cells. In THP-1 cells NA suppressed LPS-induced mRNA transcription of MCP-1 by 76.6±12.2% (P<0.01 and TNFα by 56.1±11.5% (P<0.01, yet restored LPS-induced suppression of PPARγ transcription by 536.5±46.4% (P<0.001 and its downstream effector CD36 by 116.8±19.8% (P<0.01. Whilst direct PPARγ-agonism promoted cholesterol efflux from THP-1 derived foam cells by 37.7±3.1% (P<0.01 and stimulated transcription of LXRα by 87.9±9.5% (P<0.001 and ABCG1 by 101.2±15.5% (P<0.01, NA showed no effect in foam cells on either cholesterol efflux or key RCT genes transcription. Upon foam cell induction, NA lost its effect on PPARγ and cAMP pathways, since its receptor, GPR109A, was down-regulated by foam cell transformation. This observation was confirmed in explanted human carotid plaques. In conclusion, despite NA's anti-inflammatory effect on human macrophages, it has no effect on foam cells in reverse cholesterol transport; due to GPR109A down-regulation.

  18. α7 Nicotinic receptor-mediated astrocytic gliotransmitter release: Aβ effects in a preclinical Alzheimer's mouse model.

    Directory of Open Access Journals (Sweden)

    Tiina Maria Pirttimaki

    Full Text Available It is now recognized that astrocytes participate in synaptic communication through intimate interactions with neurons. A principal mechanism is through the release of gliotransmitters (GTs such as ATP, D-serine and most notably, glutamate, in response to astrocytic calcium elevations. We and others have shown that amyloid-β (Aβ, the toxic trigger for Alzheimer's disease (AD, interacts with hippocampal α7 nicotinic acetylcholine receptors (nAChRs. Since α7nAChRs are highly permeable to calcium and are expressed on hippocampal astrocytes, we investigated whether Aβ could activate astrocytic α7nAChRs in hippocampal slices and induce GT glutamate release. We found that biologically-relevant concentrations of Aβ1-42 elicited α7nAChR-dependent calcium elevations in hippocampal CA1 astrocytes and induced NMDAR-mediated slow inward currents (SICs in CA1 neurons. In the Tg2576 AD mouse model for Aβ over-production and accumulation, we found that spontaneous astrocytic calcium elevations were of higher frequency compared to wildtype (WT. The frequency and kinetic parameters of AD mice SICs indicated enhanced gliotransmission, possibly due to increased endogenous Aβ observed in this model. Activation of α7nAChRs on WT astrocytes increased spontaneous inward currents on pyramidal neurons while α7nAChRs on astrocytes of AD mice were abrogated. These findings suggest that, at an age that far precedes the emergence of cognitive deficits and plaque deposition, this mouse model for AD-like amyloidosis exhibits augmented astrocytic activity and glutamate GT release suggesting possible repercussions for preclinical AD hippocampal neural networks that contribute to subsequent cognitive decline.

  19. Cognitive improvements in a mouse model with substituted 1,2,3-triazole agonists for nicotinic acetylcholine receptors.

    Science.gov (United States)

    Arunrungvichian, Kuntarat; Boonyarat, Chantana; Fokin, Valery V; Taylor, Palmer; Vajragupta, Opa

    2015-08-19

    The α7 nicotinic acetylcholine receptor (nAChR) is a recognized drug target for dementias of aging and certain developmental disorders. Two selective and potent α7-nAChR agonists, winnowed from a list of 43 compounds characterized in a companion article (DOI: 10.1021/acschemneuro.5b00058), 5-((quinuclid-3-yl)-1H-1,2,3-triazol-4-yl)-1H-indole (IND8) and 3-(4-hydroxyphenyl-1,2,3-triazol-1-yl) quinuclidine (QND8), were evaluated for cognitive improvement in both short- and long-term memory. Tacrine, a centrally active acetylcholinesterase inhibitor, and PNU-282987, a congeneric α7 nAChR agonist, were employed as reference standards. Three behavioral tests, modified Y-maze, object recognition test (ORT), and water maze, were performed in scopolamine-induced amnesic mice. Intraperitoneal injection of these two compounds significantly improved the cognitive impairment in a modified Y-maze test (5 μmol/kg for IND8 and 10 μmol/kg for QND8), ORT (10 μmol/kg), and water maze test (25 μmol/kg). For delay induced memory deficit or natural memory loss in mice, IND8 and QND8 at 10 μmol/kg were able to enhance memory comparable to PNU-282987 when evaluated using ORT time delay model. Cognitive enhancement of IND8 and QND8 was mediated through α7-nAChRs as evidenced by its complete abolition after pretreatment with a selective α7-nAChR antagonist, methyllycaconitine. These data demonstrate that IND8 and QND8 and their congeners are potential candidates for treatment of cognitive disorders, and the substituted triazole series formed by cycloaddition of alkynes and azides warrant further preclinical optimization.

  20. Neuroprotective effect of melatonin against ischemia is partially mediated by alpha-7 nicotinic receptor modulation and HO-1 overexpression.

    Science.gov (United States)

    Parada, Esther; Buendia, Izaskun; León, Rafael; Negredo, Pilar; Romero, Alejandro; Cuadrado, Antonio; López, Manuela G; Egea, Javier

    2014-03-01

    Melatonin has been widely studied as a protective agent against oxidative stress. However, the molecular mechanisms underlying neuroprotection in neurodegeneration and ischemic stroke are not yet well understood. In this study, we evaluated the neuroprotective/antioxidant mechanism of action of melatonin in organotypic hippocampal cultures (OHCs) as well as in photothrombotic stroke model in vivo. Melatonin (0.1, 1, and 10 μM) incubated postoxygen and glucose deprivation (OGD) showed a concentration-dependent protection; maximum protection was achieved at 10 μM (90% protection). Next, OHCs were exposed to 10 μM melatonin at different post-OGD times; the protective effect of melatonin was maintained at 0, 1, and 2 hr post-OGD treatment, but it was lost at 6 hr post-OGD. The protective effect of melatonin and the reduction in OGD-induced ROS were prevented by luzindole (melatonin antagonist) and α-bungarotoxin (α-Bgt, a selective α7 nAChR antagonist). In Nrf2 knockout mice, the protective effect of melatonin was reduced by 40% compared with controls. Melatonin, incubated 0, 1, and 2 hr post-OGD, increased the expression of heme oxygenase-1 (HO-1), and this overexpression was prevented by luzindole and α-bungarotoxin. Finally, administration of 15 mg/kg melatonin following the induction of photothrombotic stroke in vivo, reduced infarct size (50%), and improved motor skills; this effect was partially lost in 0.1 mg/kg methyllycaconitine (MLA, selective α7 nAChR antagonist)-treated mice. Taken together, these results demonstrate that postincubation of melatonin provides a protective effect that, at least in part, depends on nicotinic receptor activation and overexpression of HO-1. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Making choice between competing rewards in uncertain versus safe social environment:role of neuronal nicotinic receptors of acetylcholine

    Directory of Open Access Journals (Sweden)

    Jonathan eChabout

    2013-08-01

    Full Text Available In social environments, choosing between multiple rewards is modulated by the uncertainty of the situation. Here, we compared how mice interact with a conspecific and how they use acoustic communication during this interaction in a 3 chambers task (no social threat was possible and a Social Interaction Task, SIT (uncertain situation as two mice interact freely. We further manipulated the motivational state of the mice to see how they rank natural rewards such as social contact, food, and novelty seeking. We previously showed that beta2-subunit containing nicotinic receptors -2*nAChRs- are required for establishing reward ranking between social interaction, novelty exploration, and food consumption in social situations with high uncertainty. Knockout mice for 2*nAChRs -2-/-mice- exhibit profound impairment in making social flexible choices, as compared to control -WT- mice.Our current data shows that being confronted with a conspecific in a socially safe environment as compared to a more uncertain environment, drastically reduced communication between the two mice, and changed their way to deal with a social conspecific. Furthermore, we demonstrated for the first time, that 2-/- mice had the same motivational ranking than WT mice when placed in a socially safe environment. Therefore,2*nAChRs are not necessary for integrating social information or social rewards per se, but are important for making choices, only in a socially uncertain environment.This seems particularly important in the context of Social Neuroscience, as numerous animal models are used to provide novel insights and to test promising novel treatments of human pathologies affecting social and communication processes, among which Autistic spectrum disorders and schizophrenia.

  2. Nicotinic α4 Receptor-Mediated Cholinergic Influences on Food Intake and Activity Patterns in Hypothalamic Circuits.

    Directory of Open Access Journals (Sweden)

    Ana P García

    Full Text Available Nicotinic acetylcholine receptors (nAChRs play an important role in regulating appetite and have been shown to do so by influencing neural activity in the hypothalamus. To shed light on the hypothalamic circuits governing acetylcholine's (ACh regulation of appetite this study investigated the influence of hypothalamic nAChRs expressing the α4 subunit. We found that antagonizing the α4β2 nAChR locally in the lateral hypothalamus with di-hydro-ß-erythroidine (DHβE, an α4 nAChR antagonist with moderate affinity, caused an increase in food intake following free access to food after a 12 hour fast, compared to saline-infused animals. Immunocytochemical analysis revealed that orexin/hypocretin (HO, oxytocin, and tyrosine hydroxylase (TH-containing neurons in the A13 and A12 of the hypothalamus expressed the nAChR α4 subunit in varying amounts (34%, 42%, 50%, and 51%, respectively whereas melanin concentrating hormone (MCH neurons did not, suggesting that DHβE-mediated increases in food intake may be due to a direct activation of specific hypothalamic circuits. Systemic DHβE (2 mg/kg administration similarly increased food intake following a 12 hour fast. In these animals a subpopulation of orexin/hypocretin neurons showed elevated activity compared to control animals and MCH neuronal activity was overall lower as measured by expression of the immediate early gene marker for neuronal activity cFos. However, oxytocin neurons in the paraventricular hypothalamus and TH-containing neurons in the A13 and A12 did not show differential activity patterns. These results indicate that various neurochemically distinct hypothalamic populations are under the influence of α4β2 nAChRs and that cholinergic inputs to the lateral hypothalamus can affect satiety signals through activation of local α4β2 nAChR-mediated transmission.

  3. Trace eyeblink conditioning is impaired in α7 but not in β2 nicotinic acetylcholine receptor knock-out mice

    Directory of Open Access Journals (Sweden)

    Kevin L Brown

    2010-10-01

    Full Text Available Nicotinic acetylcholine receptors (nAChRs are essentially involved in learning and memory. A neurobiologically and behaviorally well-characterized measure of learning and memory, eyeblink classical conditioning, is sensitive to disruptions in acetylcholine neurotransmission. The two most common forms of eyeblink classical conditioning – the delay and trace paradigms - differentially engage forebrain areas densely-populated with nAChRs. The present study used genetically modified mice to investigate the effects of selective nAChR subunit deletion on delay and trace eyeblink classical conditioning. α7 and β2 nAChR subunit knockout (KO mice and their wild-type littermates were trained for 10 daily sessions in a 500 ms delay or 500 ms trace eyeblink conditioning task, matched for the interstimulus interval (ISI between conditioned stimulus (CS and unconditioned stimulus (US onset. Impairments in conditioned responding were found in α7 KO mice trained in trace – but not delay – eyeblink conditioning. Relative to littermate controls, β2 KO mice were unimpaired in the trace task but displayed higher levels of conditioned responding in delay eyeblink conditioning. Elevated conditioned response levels in delay-conditioned β2 KOs corresponded to elevated levels of alpha responding in this group. These findings suggest that α7 nAChRs play a role in normal acquisition of 500 ms trace eyeblink classical conditioning in mice. The prominent distribution of α7 nAChRs in the hippocampus and other forebrain regions may account for these genotype-specific acquisition effects in this hippocampus-dependent trace paradigm.

  4. Analysis of gait in rats with olivocerebellar lesions and ability of the nicotinic acetylcholine receptor agonist varenicline to attenuate impairments.

    Science.gov (United States)

    Lambert, C S; Philpot, R M; Engberg, M E; Johns, B E; Wecker, L

    2015-09-15

    Studies have demonstrated that administration of the neuronal nicotinic receptor agonist varenicline to rats with olivocerebellar lesions attenuates balance deficits on a rotorod and balance beam, but the effects of this drug on gait deficits have not been investigated. To accomplish this, male Sprague-Dawley rats were trained to walk on a motorized treadmill at 25 and 35 cm/s and baseline performance determined; both temporal and spatial gait parameters were analyzed. A principal component analysis (PCA) was used to identify the key components of gait, and the cumulative gait index (CGI) was calculated, representing deviations from prototypical gait patterns. Subsequently, animals either remained as non-lesioned controls or received injections of 3-acetylpyridine (3-AP)/nicotinamide to destroy the climbing fibers innervating Purkinje cells. The gait of the non-lesioned group was assessed weekly to monitor changes in the normal population, while the gait of the lesioned group was assessed 1 week following 3-AP administration, and weekly following the daily administration of saline or varenicline (0.3, 1.0, or 3.0mg free base/kg) for 2 weeks. Non-lesioned animals exhibited a 60-70% increased CGI over time due to increases in temporal gait measures, whereas lesioned animals exhibited a nearly 3-fold increased CGI as a consequence of increases in spatial measures. Following 2 weeks of treatment with the highest dose of varenicline (3.0mg free base/kg), the swing duration of lesioned animals normalized, and stride duration, stride length and step angle in this population did not differ from the non-lesioned population. Thus, varenicline enabled animals to compensate for their impairments and rectify the timing of the gait cycle. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Nicotinic α4 Receptor-Mediated Cholinergic Influences on Food Intake and Activity Patterns in Hypothalamic Circuits.

    Science.gov (United States)

    García, Ana P; Aitta-aho, Teemu; Schaaf, Laura; Heeley, Nicholas; Heuschmid, Lena; Bai, Yunjing; Barrantes, Francisco J; Apergis-Schoute, John

    2015-01-01

    Nicotinic acetylcholine receptors (nAChRs) play an important role in regulating appetite and have been shown to do so by influencing neural activity in the hypothalamus. To shed light on the hypothalamic circuits governing acetylcholine's (ACh) regulation of appetite this study investigated the influence of hypothalamic nAChRs expressing the α4 subunit. We found that antagonizing the α4β2 nAChR locally in the lateral hypothalamus with di-hydro-ß-erythroidine (DHβE), an α4 nAChR antagonist with moderate affinity, caused an increase in food intake following free access to food after a 12 hour fast, compared to saline-infused animals. Immunocytochemical analysis revealed that orexin/hypocretin (HO), oxytocin, and tyrosine hydroxylase (TH)-containing neurons in the A13 and A12 of the hypothalamus expressed the nAChR α4 subunit in varying amounts (34%, 42%, 50%, and 51%, respectively) whereas melanin concentrating hormone (MCH) neurons did not, suggesting that DHβE-mediated increases in food intake may be due to a direct activation of specific hypothalamic circuits. Systemic DHβE (2 mg/kg) administration similarly increased food intake following a 12 hour fast. In these animals a subpopulation of orexin/hypocretin neurons showed elevated activity compared to control animals and MCH neuronal activity was overall lower as measured by expression of the immediate early gene marker for neuronal activity cFos. However, oxytocin neurons in the paraventricular hypothalamus and TH-containing neurons in the A13 and A12 did not show differential activity patterns. These results indicate that various neurochemically distinct hypothalamic populations are under the influence of α4β2 nAChRs and that cholinergic inputs to the lateral hypothalamus can affect satiety signals through activation of local α4β2 nAChR-mediated transmission.

  6. The Dinoflagellate Toxin 20-Methyl Spirolide-G Potently Blocks Skeletal Muscle and Neuronal Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Aurélie Couesnon

    2016-08-01

    Full Text Available The cyclic imine toxin 20-methyl spirolide G (20-meSPX-G, produced by the toxigenic dinoflagellate Alexandrium ostenfeldii/Alexandrium peruvianum, has been previously reported to contaminate shellfish in various European coastal locations, as revealed by mouse toxicity bioassay. The aim of the present study was to determine its toxicological profile and its molecular target selectivity. 20-meSPX-G blocked nerve-evoked isometric contractions in isolated mouse neuromuscular preparations, while it had no action on contractions elicited by direct electrical stimulation, and reduced reversibly nerve-evoked compound muscle action potential amplitudes in anesthetized mice. Voltage-clamp recordings in Xenopus oocytes revealed that 20-meSPX-G potently inhibited currents evoked by ACh on Torpedo muscle-type and human α7 nicotinic acetylcholine receptors (nAChR, whereas lower potency was observed in human α4β2 nAChR. Competition-binding assays showed that 20-meSPX-G fully displaced [3H]epibatidine binding to HEK-293 cells expressing the human α3β2 (Ki = 0.040 nM, whereas a 90-fold lower affinity was detected in human α4β2 nAChR. The spirolide displaced [125I]α-bungarotoxin binding to Torpedo membranes (Ki = 0.028 nM and in HEK-293 cells expressing chick chimeric α7-5HT3 nAChR (Ki = 0.11 nM. In conclusion, this is the first study to demonstrate that 20-meSPX-G is a potent antagonist of nAChRs, and its subtype selectivity is discussed on the basis of molecular docking models.

  7. Identifying the binding site of novel methyllycaconitine (MLA) analogs at α4β2 nicotinic acetylcholine receptors.

    Science.gov (United States)

    Quek, Gracia X J; Lin, Diana; Halliday, Jill I; Absalom, Nathan; Ambrus, Joseph I; Thompson, Andrew J; Lochner, Martin; Lummis, Sarah C R; McLeod, Malcolm D; Chebib, Mary

    2010-12-15

    Neuronal nicotinic acetylcholine receptors (nAChR) are ligand gated ion channels that mediate fast synaptic transmission. Methyllycaconitine (MLA) is a selective and potent antagonist of the α7 nAChR, and its anthranilate ester side-chain is important for its activity. Here we report the influence of structure on nAChR inhibition for a series of novel MLA analogs, incorporating either an alcohol or anthranilate ester side-chain to an azabicyclic or azatricyclic core against rat α7, α4β2, and α3β4 nAChRs expressed in Xenopus oocytes. The analogs inhibited ACh (EC(50)) within an IC(50) range of 2.3-26.6 μM. Most displayed noncompetitive antagonism, but the anthranilate ester analogs exerted competitive behavior at the α7 nAChR. At α4β2 nAChRs, inhibition by the azabicyclic alcohol was voltage-dependent suggesting channel block. The channel-lining residues of α4 subunits were mutated to cysteine and the effect of azabicyclic alcohol was evaluated by competition with methanethiosulfonate ethylammonium (MTSEA) and a thiol-reactive probe in the open, closed, and desensitized states of α4β2 nAChRs. The azabicyclic alcohol was found to compete with MTSEA between residues 6' and 13' in a state-dependent manner, but the reactive probe only bonded with 13' in the open state. The data suggest that the 13' position is the dominant binding site. Ligand docking of the azabicyclic alcohol into a (α4)(3)(β2)(2) homology model of the closed channel showed that the ligand can be accommodated at this location. Thus our data reveal distinct pharmacological differences between different nAChR subtypes and also identify a specific binding site for a noncompetitive channel blocker.

  8. Differential modulation of nicotine-induced gemcitabine resistance by GABA receptor agonists in pancreatic cancer cell xenografts and in vitro

    OpenAIRE

    Banerjee, Jheelam; Al-Wadei, Hussein AN; Al-Wadei, Mohammed H.; Dagnon, Koami; Schuller, Hildegard M.

    2014-01-01

    Background Pancreatic cancer is frequently resistant to cancer therapeutics. Smoking and alcoholism are risk factors and pancreatic cancer patients often undergo nicotine replacement therapy (NRT) and treatment for alcohol dependence. Based on our report that low dose nicotine within the range of NRT causes gemcitabine resistance in pancreatic cancer, our current study has tested the hypothesis that GABA or the selective GABA-B-R agonist baclofen used to treat alcohol dependence reverse nicot...

  9. alpha(7) Nicotinic acetylcholine receptor activation prevents behavioral and molecular changes induced by repeated phencyclidine treatment

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Christensen, Ditte Z; Hansen, Henrik H

    2009-01-01

    , and administration of the NMDA-antagonist phencyclidine (PCP) in rodents is a well validated model of such cognitive deficits. Here we show that repeated PCP treatment (10 mg/kg/day for 10 days) decreased the expression of parvalbumin and synaptophysin mRNA in the mouse PFC, which corresponds to changes seen...

  10. Randomized, Double-Blind, Placebo-Controlled Study of Encenicline, an α7 Nicotinic Acetylcholine Receptor Agonist, as a Treatment for Cognitive Impairment in Schizophrenia.

    Science.gov (United States)

    Keefe, Richard S E; Meltzer, Herbert A; Dgetluck, Nancy; Gawryl, Maria; Koenig, Gerhard; Moebius, Hans J; Lombardo, Ilise; Hilt, Dana C

    2015-12-01

    Encenicline is a novel, selective α7 nicotinic acetylcholine receptor agonist in development for treating cognitive impairment in schizophrenia and Alzheimer's disease. A phase 2, double-blind, randomized, placebo-controlled, parallel-design, multinational study was conducted. Patients with schizophrenia on chronic stable atypical antipsychotics were randomized to encenicline 0.27 or 0.9 mg once daily or placebo for 12 weeks. The primary efficacy end point was the Overall Cognition Index (OCI) score from the CogState computerized battery. Secondary end points include MATRICS Consensus Cognitive Battery (MCCB) (in US patients), the Schizophrenia Cognition Rating Scale (SCoRS) total score, SCoRS global rating, and Positive and Negative Syndrome Scale (PANSS) total and subscale and cognition factor scores. Of 319 randomized patients, 317 were included in the safety population, and 307 were included in the intent-to-treat population. Notable trends in improvement were demonstrated across all cognition scales. For the OCI score, the LS mean difference for encenicline 0.27 mg vs placebo was significant (Cohen's d=0.257; P=0.034). Mean SCoRS total scores decreased showing improvement in function over time, and the difference was significant for encenicline 0.9 mg vs placebo (P=0.011). Furthermore, the difference between encenicline 0.9 mg and placebo was significant for the PANSS Cognition Impairment Domain (P=0.0098, Cohen's d=0.40) and for the PANSS Negative scale (P=0.028, Cohen's d=0.33). Treatment-emergent adverse events were reported at similar frequencies across all treatment groups (39.0% with placebo, 23.4% with encenicline 0.27 mg, and 33.3% with encenicline 0.9 mg). Overall, encenicline was generally well tolerated and demonstrated clinically meaningful improvements in cognition and function in patients with schizophrenia.

  11. Sex Differences and Drug Dose Influence the Role of the α7 Nicotinic Acetylcholine Receptor in the Mouse Dextran Sodium Sulfate-Induced Colitis Model.

    Science.gov (United States)

    AlSharari, Shakir D; Bagdas, Deniz; Akbarali, Hamid I; Lichtman, Patraic A; Raborn, Erinn S; Cabral, Guy A; Carroll, F Ivy; McGee, Elizabeth A; Damaj, M Imad

    2017-04-01

    α7 nicotinic acetylcholine receptors (nAChRs) play an important role in vagus nerve-based cholinergic anti-inflammatory effects. This study was designed to assess the role of α7 nAChRs in dextran sodium sulfate (DSS)-induced colitis in male and female mouse. We first compared disease activity and pathogenesis of colitis in α7 knockout and wild-type mice. We then evaluated the effect of several α7 direct and indirect agonists on the severity of disease in the DSS-induced colitis. Male and female adult mice were administered 2.5% DSS solution freely in the drinking water for 7 consecutive days and the colitis severity (disease activity index) was evaluated as well as colon length, colon histology, and levels of tumor necrosis factor-alpha colonic levels. Male, but not female, α7 knockout mice displayed a significantly increased colitis severity and higher tumor necrosis factor-alpha levels as compared with their littermate wild-type mice. Moreover, pretreatment with selective α7 ligands PHA-543613, choline, and PNU-120596 decreased colitis severity in male but not female mice. The anti-colitis effects of these α7 compounds dissipated when administered at higher doses. Our results suggest the presence of a α7-dependent anti-colitis endogenous tone in male mice. Finally, our results show for the first time that female mice are less sensitive to the anti-colitis activity of α7 agonists. Ovarian hormones may play a key role in the sex difference effect of α7 nAChRs modulation of colitis in the mouse. Our collective results suggest that targeting α7 nAChRs could represent a viable therapeutic approach for intestinal inflammation diseases such as ulcerative colitis with the consideration of sex differences.

  12. Activation of α-7 nicotinic acetylcholine receptor reduces ischemic stroke injury through reduction of pro-inflammatory macrophages and oxidative stress.

    Directory of Open Access Journals (Sweden)

    Zhenying Han

    Full Text Available Activation of α-7 nicotinic acetylcholine receptor (α-7 nAchR has a neuro-protective effect on ischemic and hemorrhagic stroke. However, the underlying mechanism is not completely understood. We hypothesized that α-7 nAchR agonist protects brain injury after ischemic stroke through reduction of pro-inflammatory macrophages (M1 and oxidative stress. C57BL/6 mice were treated with PHA568487 (PHA, α-7 nAchR agonist, methyllycaconitine (MLA, nAchR antagonist, or saline immediately and 24 hours after permanent occlusion of the distal middle cerebral artery (pMCAO. Behavior test, lesion volume, CD68(+, M1 (CD11b(+/Iba1(+ and M2 (CD206/Iba1+ microglia/macrophages, and phosphorylated p65 component of NF-kB in microglia/macrophages were quantified using histological stained sections. The expression of M1 and M2 marker genes, anti-oxidant genes and nicotinamide adenine dinucleotide phosphate (NADPH oxidase were quantified using real-time RT-PCR. Compared to the saline-treated mice, PHA mice had fewer behavior deficits 3 and 7 days after pMCAO, and smaller lesion volume, fewer CD68(+ and M1 macrophages, and more M2 macrophages 3 and 14 days after pMCAO, whereas MLA's effects were mostly the opposite in several analyses. PHA increased anti-oxidant genes and NADPH oxidase expression associated with decreased phosphorylation of NF-kB p65 in microglia/macrophages. Thus, reduction of inflammatory response and oxidative stress play roles in α-7 nAchR neuro-protective effect.

  13. Multiple transmembrane binding sites for p-trifluoromethyldiazirinyl-etomidate, a photoreactive Torpedo nicotinic acetylcholine receptor allosteric inhibitor.

    Science.gov (United States)

    Hamouda, Ayman K; Stewart, Deirdre S; Husain, S Shaukat; Cohen, Jonathan B

    2011-06-10

    Photoreactive derivatives of the general anesthetic etomidate have been developed to identify their binding sites in γ-aminobutyric acid, type A and nicotinic acetylcholine receptors. One such drug, [(3)H]TDBzl-etomidate (4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzyl-[(3)H]1-(1-phenylethyl)-1H-imidazole-5-carboxylate), acts as a positive allosteric potentiator of Torpedo nACh receptor (nAChR) and binds to a novel site in the transmembrane domain at the γ-α subunit interface. To extend our understanding of the locations of allosteric modulator binding sites in the nAChR, we now characterize the interactions of a second aryl diazirine etomidate derivative, TFD-etomidate (ethyl-1-(1-(4-(3-trifluoromethyl)-3H-diazirin-3-yl)phenylethyl)-1H-imidazole-5-carboxylate). TFD-etomidate inhibited acetylcholine-induced currents with an IC(50) = 4 μM, whereas it inhibited the binding of [(3)H]phencyclidine to the Torpedo nAChR ion channel in the resting and desensitized states with IC(50) values of 2.5 and 0.7 mm, respectively. Similar to [(3)H]TDBzl-etomidate, [(3)H]TFD-etomidate bound to a site at the γ-α subunit interface, photolabeling αM2-10 (αSer-252) and γMet-295 and γMet-299 within γM3, and to a site in the ion channel, photolabeling amino acids within each subunit M2 helix that line the lumen of the ion channel. In addition, [(3)H]TFD-etomidate photolabeled in an agonist-dependent manner amino acids within the δ subunit M2-M3 loop (δIle-288) and the δ subunit transmembrane helix bundle (δPhe-232 and δCys-236 within δM1). The fact that TFD-etomidate does not compete with ion channel blockers at concentrations that inhibit acetylcholine responses indicates that binding to sites at the γ-α subunit interface and/or within δ subunit helix bundle mediates the TFD-etomidate inhibitory effect. These results also suggest that the γ-α subunit interface is a binding site for Torpedo nAChR negative allosteric modulators (TFD-etomidate) and for positive

  14. Multiple Transmembrane Binding Sites for p-Trifluoromethyldiazirinyl-etomidate, a Photoreactive Torpedo Nicotinic Acetylcholine Receptor Allosteric Inhibitor*

    Science.gov (United States)

    Hamouda, Ayman K.; Stewart, Deirdre S.; Husain, S. Shaukat; Cohen, Jonathan B.

    2011-01-01

    Photoreactive derivatives of the general anesthetic etomidate have been developed to identify their binding sites in γ-aminobutyric acid, type A and nicotinic acetylcholine receptors. One such drug, [3H]TDBzl-etomidate (4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzyl-[3H]1-(1-phenylethyl)-1H-imidazole-5-carboxylate), acts as a positive allosteric potentiator of Torpedo nACh receptor (nAChR) and binds to a novel site in the transmembrane domain at the γ-α subunit interface. To extend our understanding of the locations of allosteric modulator binding sites in the nAChR, we now characterize the interactions of a second aryl diazirine etomidate derivative, TFD-etomidate (ethyl-1-(1-(4-(3-trifluoromethyl)-3H-diazirin-3-yl)phenylethyl)-1H-imidazole-5-carboxylate). TFD-etomidate inhibited acetylcholine-induced currents with an IC50 = 4 μm, whereas it inhibited the binding of [3H]phencyclidine to the Torpedo nAChR ion channel in the resting and desensitized states with IC50 values of 2.5 and 0.7 mm, respectively. Similar to [3H]TDBzl-etomidate, [3H]TFD-etomidate bound to a site at the γ-α subunit interface, photolabeling αM2-10 (αSer-252) and γMet-295 and γMet-299 within γM3, and to a site in the ion channel, photolabeling amino acids within each subunit M2 helix that line the lumen of the ion channel. In addition, [3H]TFD-etomidate photolabeled in an agonist-dependent manner amino acids within the δ subunit M2-M3 loop (δIle-288) and the δ subunit transmembrane helix bundle (δPhe-232 and δCys-236 within δM1). The fact that TFD-etomidate does not compete with ion channel blockers at concentrations that inhibit acetylcholine responses indicates that binding to sites at the γ-α subunit interface and/or within δ subunit helix bundle mediates the TFD-etomidate inhibitory effect. These results also suggest that the γ-α subunit interface is a binding site for Torpedo nAChR negative allosteric modulators (TFD-etomidate) and for positive modulators (TDBzl

  15. Mutation of a nicotinic acetylcholine receptor β subunit is associated with resistance to neonicotinoid insecticides in the aphid Myzus persicae.

    Science.gov (United States)

    Bass, Chris; Puinean, Alin M; Andrews, Melanie; Cutler, Penny; Daniels, Miriam; Elias, Jan; Paul, Verity Laura; Crossthwaite, Andrew J; Denholm, Ian; Field, Linda M; Foster, Stephen P; Lind, Rob; Williamson, Martin S; Slater, Russell

    2011-05-31

    Myzus persicae is a globally important aphid pest with a history of developing resistance to insecticides. Unusually, neonicotinoids have remained highly effective as control agents despite nearly two decades of steadily increasing use. In this study, a clone of M. persicae collected from southern France was found, for the first time, to exhibit sufficiently strong resistance to result in loss of the field effectiveness of neonicotinoids. Bioassays, metabolism and gene expression studies implied the presence of two resistance mechanisms in the resistant clone, one based on enhanced detoxification by cytochrome P450 monooxygenases, and another unaffected by a synergist that inhibits detoxifying enzymes. Binding of radiolabeled imidacloprid (a neonicotinoid) to whole body membrane preparations showed that the high affinity [3H]-imidacloprid binding site present in susceptible M. persicae is lost in the resistant clone and the remaining lower affinity site is altered compared to susceptible clones. This confers a significant overall reduction in binding affinity to the neonicotinoid target: the nicotinic acetylcholine receptor (nAChR). Comparison of the nucleotide sequence of six nAChR subunit (Mpα1-5 and Mpβ1) genes from resistant and susceptible aphid clones revealed a single point mutation in the loop D region of the nAChR β1 subunit of the resistant clone, causing an arginine to threonine substitution (R81T). Previous studies have shown that the amino acid at this position within loop D is a key determinant of neonicotinoid binding to nAChRs and this amino acid change confers a vertebrate-like character to the insect nAChR receptor and results in reduced sensitivity to neonicotinoids. The discovery of the mutation at this position and its association with the reduced affinity of the nAChR for imidacloprid is the first example of field-evolved target-site resistance to neonicotinoid insecticides and also provides further validation of exisiting models of

  16. Mutation of a nicotinic acetylcholine receptor β subunit is associated with resistance to neonicotinoid insecticides in the aphid Myzus persicae

    Directory of Open Access Journals (Sweden)

    Field Linda M

    2011-05-01

    Full Text Available Abstract Background Myzus persicae is a globally important aphid pest with a history of developing resistance to insecticides. Unusually, neonicotinoids have remained highly effective as control agents despite nearly two decades of steadily increasing use. In this study, a clone of M. persicae collected from southern France was found, for the first time, to exhibit sufficiently strong resistance to result in loss of the field effectiveness of neonicotinoids. Results Bioassays, metabolism and gene expression studies implied the presence of two resistance mechanisms in the resistant clone, one based on enhanced detoxification by cytochrome P450 monooxygenases, and another unaffected by a synergist that inhibits detoxifying enzymes. Binding of radiolabeled imidacloprid (a neonicotinoid to whole body membrane preparations showed that the high affinity [3H]-imidacloprid binding site present in susceptible M. persicae is lost in the resistant clone and the remaining lower affinity site is altered compared to susceptible clones. This confers a significant overall reduction in binding affinity to the neonicotinoid target: the nicotinic acetylcholine receptor (nAChR. Comparison of the nucleotide sequence of six nAChR subunit (Mpα1-5 and Mpβ1 genes from resistant and susceptible aphid clones revealed a single point mutation in the loop D region of the nAChR β1 subunit of the resistant clone, causing an arginine to threonine substitution (R81T. Conclusion Previous studies have shown that the amino acid at this position within loop D is a key determinant of neonicotinoid binding to nAChRs and this amino acid change confers a vertebrate-like character to the insect nAChR receptor and results in reduced sensitivity to neonicotinoids. The discovery of the mutation at this position and its association with the reduced affinity of the nAChR for imidacloprid is the first example of field-evolved target-site resistance to neonicotinoid insecticides and also

  17. Identification of a neuregulin and protein-tyrosine phosphatase response element in the nicotinic acetylcholine receptor epsilon subunit gene: regulatory role of an Rts transcription factor.

    Science.gov (United States)

    Sapru, M K; Florance, S K; Kirk, C; Goldman, D

    1998-02-03

    At the neuromuscular synapse, innervation induces endplate-specific expression of adult-type nicotinic acetylcholine receptors by selective expression of their subunit-encoding genes (alpha2betaepsilondelta) in endplate-associated myonuclei. These genes are specifically regulated by protein-tyrosine phosphatase (PTPase) activity. In addition, neuregulin/acetylcholine-receptor-inducing activity, a nerve-derived factor that stimulates nicotinic acetylcholine receptor synthesis, induces adult-type specific epsilon subunit gene expression via activation of a Ras/mitogen-activated protein kinase pathway. However, the DNA regulatory elements and the binding proteins that mediate PTPase and neuregulin-dependent gene expression remain unknown. Herein we report that PTPase, neuregulin, and Ras-dependent regulation of the epsilon subunit gene map to a 15-bp promoter sequence. Interestingly, this same 15-bp sequence appears to be necessary for low epsilon subunit gene expression in extrajunctional regions of the muscle fiber. Site-directed mutagenesis of a putative Ets binding site located within this 15-bp sequence, reduced PTPase, neuregulin, and Ras-dependent regulation. Overexpression of the rat muscle Ets-2 transcription factor resulted in a sequence-specific induction of epsilon subunit promoter activity. Further, a dominant negative mutant of Ets-2 abolished neuregulin-dependent induction of epsilon subunit gene expression. Thus, these results indicate a crucial role for the 15-bp element in determining synapse-specific and neuregulin-mediated motor neuron control of epsilon subunit gene expression and suggest the participation of Ets transcription factor(s) in this control.

  18. Cholinergic modulation of dopaminergic reward areas: upstream and downstream targets of nicotine addiction

    NARCIS (Netherlands)

    Mansvelder, H.D.; de Rover, M.; McGehee, D.S.; Brussaard, A.B.

    2003-01-01

    Nicotine reinforces smoking behaviour by activating nicotinic acetylcholine receptors in the midbrain dopaminergic reward centres. Upstream of the dopaminergic neurons nicotine induces long-term potentiation of the excitatory input to dopamine cells in the ventral tegmental area, and depresses

  19. Structure-activity studies of diazabicyclo[3.3.0]octane-substituted pyrazines and pyridines as potent α4β2 nicotinic acetylcholine receptor ligands.

    Science.gov (United States)

    Scanio, Marc J C; Shi, Lei; Bunnelle, William H; Anderson, David J; Helfrich, Rosalind J; Malysz, John; Thorin-Hagene, Kirsten K; Van Handel, Ceclia E; Marsh, Kennan C; Lee, Chih-Hung; Gopalakrishnan, Murali

    2011-11-10

    A series of diazabicyclo[3.3.0]octane substituted pyridines and pyrazines was synthesized and characterized at the α4β2 neuronal nicotinic acetylcholine receptor (nAChR). The compounds were designed to mimic the profile of ABT-089, high affinity binding ligand for the α4β2 nAChR, with limited agonist activity. Carboxamide derivatives of 3-(diazabicyclo[3.3.0]octane)-substituted pyridines or 2-(diazabicyclo[3.3.0]octane)-substituted pyrazines were found to have the desired binding and activity profile. The structure-activity relationship of these compounds is presented.

  20. Lynx1 and Aβ1-42 bind competitively to multiple nicotinic acetylcholine receptor subtypes

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Arvaniti, Maria; Jensen, Majbrit M

    2016-01-01

    are decreased in a transgenic mouse model with concomitant β-amyloid and tau pathology. Our data suggest that Lynx1 binds to multiple nAChR subtypes in the brain and that this interaction might have functional and pathophysiological implications in relation to Alzheimer's disease....... to demonstrate that a water-soluble variant of human Lynx1 (Ws-Lynx1) isolates α3, α4, α5, α6, α7, β2, and β4 nAChR subunits from human and rat cortical extracts, and rat midbrain and olfactory bulb extracts, suggesting that Lynx1 forms complexes with multiple nAChR subtypes in the human and rodent brain...

  1. Expression of Estrogen Receptor Alpha and Beta is Decreased in Hypospadias

    Science.gov (United States)

    Qiao, Liang; Rodriguez, Esequiel; Weiss, Dana A.; Ferretti, Max; Risbridger, Gail; Cunha, Gerald R.; Baskin, Laurence S.

    2012-01-01

    Purpose Estrogenic endocrine disruptors acting via estrogen receptors α and β have been implicated in the etiology of hypospadias. However, the expression and distribution of estrogen receptors α and β in normal and hypospadiac human foreskins is unknown. We characterized the location and expression of estrogen receptors α and β in normal and hypospadiac foreskins. Materials and Methods We prospectively collected excess foreskin from 35 patients undergoing hypospadias repair and 15 patients undergoing elective circumcision. Hypospadias was classified as severe in 18 patients and mild in 17 based on the ectopic position of the meatus. mRNA expression levels in estrogen receptors α and β were quantified using reverse transcriptase polymerase chain reaction. Receptor location was characterized by immunohistochemical analysis. Additionally immunohistochemical analysis was performed in 4 archived human fetal penises. Results Mean ± SD ages were similar for the circumcision (9.5 ± 3 months) and hypospadias repair groups (9 ± 3 months, p = 0.75). mRNA expression levels in estrogen receptors α and β were significantly decreased in hypospadiac foreskin cases compared to controls (p hypospadias. Estrogen receptor β immunostaining was strong in normal foreskin but weak in hypospadiac foreskin. Estrogen receptor β immunoreactivity was most intense in the stratum basale and stratum spinosum. Estrogen receptor α immunostaining was weak in normal and mild hypospadias foreskin, and undetectable in severe hypospadias. Fetal penises expressed strong estrogen receptor β immunopositivity in the urethral plate epithelium, corpus spongiosum, corpora cavernosa and penile skin, while estrogen receptor α immunostaining was not detected. Conclusions These data demonstrate a difference in estrogen receptor α and β expression and location in the foreskin of patients with hypospadias compared to controls. These findings are consistent with aberrant estrogenic effects having

  2. Nicotine Dependence, Nicotine Metabolism, and the Extent of Compensation in Response to Reduced Nicotine Content Cigarettes.

    Science.gov (United States)

    Bandiera, Frank C; Ross, Kathryn C; Taghavi, Seyedehtaraneh; Delucchi, Kevin; Tyndale, Rachel F; Benowitz, Neal L

    2015-09-01

    The Food and Drug Administration has the authority to regulate tobacco product constituents, including nicotine, to promote public health. Reducing the nicotine content in cigarettes may lead to lower levels of addiction. Smokers however may compensate by smoking more cigarettes and/or smoking more intensely. The objective of this study was to test whether individual differences in the level of nicotine dependence (as measured by the Fagerstrom Test of Cigarette Dependence [FTCD]) and/or the rate of nicotine metabolism influence smoking behavior and exposure to tobacco toxicants when smokers are switched to reduced nicotine content cigarettes (RNC). Data from 51 participants from a previously published clinical trial of RNC were analyzed. Nicotine content of cigarettes was progressively reduced over 6 months and measures of smoking behavior, as well as nicotine metabolites and tobacco smoke toxicant exposure, CYP2A6 and nicotinic CHRNA5-A3-B4 (rs1051730) genotype were measured. Higher baseline FTCD predicted smoking more cigarettes per day (CPD), higher cotinine and smoke toxicant levels while smoking RNC throughout the study, with no interaction by RNC level. Time to first cigarette (TFC) was associated with differences in compensation. TFC within 10 min was associated with a greater increase in CPD compared to TFC greater than 10 min. Neither rate of nicotine metabolism, nor CYP2A6 or nicotinic receptor genotype, had an effect on the outcome variables of interest. FTCD is associated with overall exposure to nicotine and other constituents of tobacco smoke, while a short TFC is associated with an increased compensatory response after switching to RNC. © The Author 2015. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Nicotinic acetylcholine receptors containing the α7-like subunit mediate contractions of muscles responsible for space positioning of the snail, Helix pomatia L. tentacle.

    Directory of Open Access Journals (Sweden)

    Tibor Kiss

    Full Text Available Three recently discovered tentacle muscles are crucial to perform patterned movements of upper tentacles of the terrestrial snail, Helix pomatia. The muscles receive central and peripheral excitatory cholinergic innervation lacking inhibitory innervation. Here, we investigate the pharmacology of acetylcholine (ACh responses in muscles to determine the properties of the ACh receptor (AChR, the functional availability of which was assessed using isotonic contraction measurement. Using broad spectrum of nicotinic and muscarinic ligands, we provide the evidence that contractions in the muscles are attributable to the activation of nAChRs that contain the α7-like subunit. Contractions could be evoked by nicotine, carbachol, succinylchloride, TMA, the selective α7-nAChR agonist choline chloride, 3-Bromocytisine and PNU-282987, and blocked by nAChR selective antagonists such as mytolon, hexamethonium, succinylchloride, d-tubocurarine, hemicholinium, DMDA (decamethonium, methyllycaconitine, α-Bungarotoxin (αBgTx and α-Conotoxin IMI. The specific muscarinic agonist oxotremorine and arecoline failed to elicit contractions. Based on these pharmacological properties we conclude that the Na+ and Ca2+ permeable AChRs of the flexor muscle are nicotinic receptors that contain the α7-like subunit. Immunodetection experiments confirmed the presence of α7- or α7-like AChRs in muscle cells, and α4-AChRs in nerves innervating the muscle. These results support the conclusion that the slowly desensitizing αBgTx-sensitive responses obtained from flexor muscles are produced by activation of α7- like AChRs. This is the first demonstration of postsynaptic expression and an obligatory role for a functional α7-like nAChR in the molluscan periphery.

  4. The Sleep–Wake Cycle in the Nicotinic Alpha-9 Acetylcholine Receptor Subunit Knock-Out Mice

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    Natalia Madrid-López

    2017-10-01

    Full Text Available There is a neural matrix controlling the sleep–wake cycle (SWC embedded within high ranking integrative mechanisms in the central nervous system. Nicotinic alpha-9 acetylcholine receptor subunit (alpha-9 nAChR participate in physiological processes occurring in sensory, endocrine and immune systems. There is a relationship between the SWC architecture, body homeostasis and sensory afferents so that disruption of afferent signaling is expected to affect the temporal organization of sleep and wake states. The analysis of the SWC of 9 nAChR knock-out animals may help to reveal the contribution of alpha-9 nAChR to sleep chronobiological determinants. Here we explore the polysomnogram in chronically implanted alpha-9 nAChR knock-out (KO and wild-type (WT individuals of the hybrid CBA/Sv129 mouse strain. Records were obtained in isolation chambers under a stable 12:12 light:dark cycle (LD. To unmask the 24-h modulation of the SWC a skeleton photoperiod (SP protocol was performed. Under LD the daily quota (in % of wakefulness (W, NREM sleep and REM sleep obtained in KO and WT animals were 45, 48 and 7, and 46, 46 and 8 respectively. Both groups exhibit nocturnal phase preference of W as well as diurnal and unimodal phase preference of NREM and REM sleep. The acrophase mean angles of KO vs. WT genotypes were not different (Zeitgeber Time: 6.5 vs. 14.9 for W, 4.3 vs. 2.8 for NREM sleep and 5.3 vs. 3.4 for REM sleep, respectively. Transference to SP do not affect daily state quotas, phase preferences and acrophases among genotypes. Unmasking phenomena of the SWC such as wake increment during the rest phase under SP was evident only among WT mice suggesting the involvement of retinal structures containing alpha-9 nAChR in masking processes. Furthermore, KO animals exhibit longer NREM and REM sleep episodes that is independent of illumination conditions. Consolidated diurnal NREM sleep contributed to obtain higher values of NREM sleep delta-EEG activity

  5. Differential immediate and sustained memory enhancing effects of alpha7 nicotinic receptor agonists and allosteric modulators in rats.

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    Morten S Thomsen

    Full Text Available The α7 nicotinic acetylcholine receptor (nAChR is a potential target for the treatment of cognitive deficits in patients with schizophrenia, ADHD and Alzheimer's disease. Here we test the hypothesis that upregulation of α7 nAChR levels underlies the enhanced and sustained procognitive effect of repeated administration of α7 nAChR agonists. We further compare the effect of agonists to that of α7 nAChR positive allosteric modulators (PAMs, which do not induce upregulation of the α7 nAChR. Using the social discrimination test as a measure of short-term memory, we show that the α7 nAChR agonist A-582941 improves short-term memory immediately after repeated (7× daily, but not a single administration. The α7 nAChR PAMs PNU-120596 and AVL-3288 do not affect short-term memory immediately after a single or repeated administration. This demonstrates a fundamental difference in the behavioral effects of agonists and PAMs that may be relevant for clinical development. Importantly, A-582941 and AVL-3288 increase short-term memory 24 hrs after repeated, but not a single, administration, suggesting that repeated administration of both agonists and PAMs may produce sustained effects on cognitive performance. Subsequent [(125I]-bungarotoxin autoradiography revealed no direct correlation between α7 nAChR levels in frontal cortical or hippocampal brain regions and short-term memory with either compound. Additionally, repeated treatment with A-582941 did not affect mRNA expression of RIC-3 or the lynx-like gene products lynx1, lynx2, PSCA, or Ly6H, which are known to affect nAChR function. In conclusion, both α7 nAChR agonists and PAMs exhibit sustained pro-cognitive effects after repeated administration, and altered levels of the α7 nAChR per se, or that of endogenous regulators of nAChR function, are likely not the major cause of this effect.

  6. Vagus Nerve Attenuates Hepatocyte Apoptosis upon Ischemia-Reperfusion via α7 Nicotinic Acetylcholine Receptor on Kupffer Cells in Mice.

    Science.gov (United States)

    Ni, Min; Fu, Hui; Huang, Fang; Zhao, Ting; Chen, Ji-Kuai; Li, Dong-Jie; Shen, Fu-Ming

    2016-11-01

    Hepatic ischemia-reperfusion (HIR) injury is a complication of liver surgery. As much as 50% of hepatocytes undergo apoptosis within the first 24 h of reperfusion. The neurotransmitters of the vagus nerve can activate α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages. The function of Kupffer cells (KCs) determines HIR injury. We hypothesize that the vagus nerve could attenuate HIR-induced hepatocyte apoptosis by activating α7nAChR on KCs. Hepatic vagotomized C57BL/6J mice, KC-eliminated C57BL/6J mice, and α7nAChR mice were used for HIR. Primary KCs and hepatocytes were subjected to hypoxia/reoxygenation (HR). Liver injury, hepatocyte apoptosis, reactive oxygen species (ROS) production, and soluble CD163 were measured. Hepatic vagotomy and α7nAChR caused higher levels of alanine transaminase and liver caspase-3 and -8 activity by HIR. Activating α7nAChR attenuated these changes in wild-type but not in the α7nAChR mice. Furthermore, activating α7nAChR diminished hepatic injury and reduced liver apoptosis by HIR in vagotomized mice. In vitro, activating α7nAChR reduced apoptosis of hepatocytes cocultured with KCs that suffered HR. Similar to the effects by catalase, activating α7nAChR on KCs reduced ROS and H2O2 by HR. The supernatant from KCs, with α7nAChR activated or catalase treated, prevented hepatocyte apoptosis by HR. Finally, KC elimination reduced HIR-induced H2O2 production in mice. Activating α7nAChR significantly attenuated soluble CD163 both in mice by HIR (serum: 240 ± 34 vs. 446 ± 72; mean ± SD; n = 8; P vagus nerve could minimize HIR-induced liver apoptosis through activating α7nAChR on KCs possibly by preventing their excessive ROS production.

  7. Glucose attenuates impairments in memory and CREB activation produced by an α4β2 but not an α7 nicotinic receptor antagonist.

    Science.gov (United States)

    Morris, Ken A; Li, Sisi; Bui, Duat D; Gold, Paul E

    2013-04-01

    Glucose improves memory for a variety of tasks when administered to rats and mice near the time of training. Prior work indicates glucose may enhance memory by increasing the synthesis and release of the neurotransmitter acetylcholine in the brain. To investigate if specific acetylcholine receptor subtypes may mediate some of the memory-enhancing actions of glucose, we examined the effects of subtype-specific nicotinic acetylcholine receptor antagonists on memory in Fischer-344 rats and also examined the ability of glucose to reverse drug-induced impairments. Pre-training peripheral injections of methyllycaconitine (MLA) or dihydro-beta-erythroidine (DHβE), which are specific α7 and α4β2 nicotinic receptor antagonists, respectively, dose-dependently impaired retention latencies in an inhibitory avoidance task when tested 7-days but not 1 h after training. Immediate post-training glucose injections attenuated the impairments, but were more effective in attenuating the DHβE-induced impairments. Likewise, peripheral or direct intrahippocampal injections of MLA or DHβE dose-dependently impaired spatial working memory scores on a spontaneous alternation task. Concurrent administration of glucose reversed DHβE- but not MLA-induced impairments. CREB phosphorylation downstream of cholinergic signaling was assessed 30 min after spontaneous alternation testing and intrahippocampal drug infusions. Both MLA and DHβE impaired hippocampal CREB phosphorylation; glucose reversed DHβE- but not MLA-induced deficits. The effectiveness of glucose in reversing DHβE- but not MLA-induced impairments in behavioral performance and CREB phosphorylation suggests that activation of α7 receptors may play an important role in memory enhancement by glucose. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Direct action and modulating effect of (+)- and (-)-nicotine on ion channels expressed in trigeminal sensory neurons.

    Science.gov (United States)

    Schreiner, Benjamin S P; Lehmann, Ramona; Thiel, Ulrike; Ziemba, Paul M; Beltrán, Leopoldo R; Sherkheli, Muhammad A; Jeanbourquin, Philippe; Hugi, Alain; Werner, Markus; Gisselmann, Günter; Hatt, Hanns

    2014-04-05

    Nicotine sensory perception is generally thought to be mediated by nicotinic acetylcholine (nACh) receptors. However, recent data strongly support the idea that other receptors (e.g., transient receptor potential A1 channel, TRPA1) and other pathways contribute to the detection mechanisms underlying the olfactory and trigeminal cell response to nicotine flavor. This is in accordance with the reported ability of humans to discriminate between (+)- and (-)- nicotine enantiomers. To get a more detailed understanding of the molecular and cellular basis underlying the sensory perception of nicotine, we studied the activity of (+)- and (-)-nicotine on cultured murine trigeminal sensory neurons and on a range of heterologously expressed receptors. The human TRPA1 channel is activated by (-)-nicotine. In this work, we show that (+)-nicotine is also an activator of this channel. Pharmacological experiments using nicotinic acetylcholine receptors and transient receptor potential blockers revealed that trigeminal neurons express one or more unidentified receptors that are sensitive to (+)- and/or (-)-nicotine. Results also indicate that the presence of extracellular calcium ions is required to elicit trigeminal neuron responses to (+)- and (-)-nicotine. Results also show that both (+)-nicotine and (-)-nicotine can block 5-hydroxytryptamine type 3 (5-HT3) receptor-mediated responses in recombinant expression systems and in cultured trigeminal neurons expressing 5-HT3 receptors. Our investigations broaden the spectra of receptors that are targets for nicotine enantiomers and give new insights into the physiological role of nicotine. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. The Effects of Intra-Amygdala Injection of Nicotine and Harmaline on Anxiey-Related Behavior in Adult Male Rat

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    Gh. Vaezi

    2012-07-01

    Full Text Available B-carboline alkaloids such as harmaline and nicotine are naturally present in the human food chain. Plants which contain B-caroline have anxiety and hallucinogenic effects. In this study the change in like – anxiety behaviors was investigated after intra- amygdala injections of nicotine and harmaline and intra action of them in male rat. Different doses of Harmaline, Nicotine and its compounds were applied for 30 minutes, before test of anxiety injection to (CeA amygdale. Then like anxiety behavior include open arm time and Locomotor activity, spent open arm time, entriar open arm in maze were examined for 5 minute . Bilateral injection of Harmaline and Nicotine was decreased in to (CeA amygdale one-by- one open arm times in control group. Injections of effective does of Nicotine could increase anxiety effects of Harmaline. Furthermore, Injection of ineffective doses of drugs has increased anxiety. The results show that Harmaline and Nicotine have anxiety effects. Also muscarinic and Nicotine receptor have important role in Like- anxiety behaviors. Acetylcholine in CeA amygdale thorough Nicotine receptors caused anxiety behaviors. Joined injection increased them effective.

  10. Nicotine activates nuclear factor of activated T cells c2 (NFATc2) and prevents cell cycle entry in T cells.

    Science.gov (United States)

    Frazer-Abel, Ashley A; Baksh, Shairaz; Fosmire, Susan P; Willis, Derall; Pierce, Angela M; Meylemans, Heather; Linthicum, Darwin S; Burakoff, Steven J; Coons, Teresa; Bellgrau, Donald; Modiano, Jaime F

    2004-11-01

    We used primary peripheral blood T cells, a population that exists in G(0) and can be stimulated to enter the cell cycle synchronously, to define more precisely the effects of nicotine on pathways that control cell cycle entry and progression. Our data show that nicotine decreased the ability of T cells to transit through the G(0)/G(1) boundary (acquire competence) and respond to progression signals. These effects were due to nuclear factor of activated T cells c2 (NFATc2)-dependent repression of cyclin-dependent kinase 4 (CDK4) expression. Growth arrest at the G(0)/G(1) boundary was further enforced by inhibition of cyclin D2 expression and by increased expression and stabilization of p27Kip1. Intriguingly, T cells from habitual users of tobacco products and from NFATc2-deficient mice constitutively expressed CDK4 and were resistant to the antiproliferative effects of nicotine. These results indicate that nicotine impairs T cell cycle entry through NFATc2-dependent mechanisms and suggest that, in the face of chronic nicotine exposure, selection may favor cells that can evade these effects. We postulate that cross talk between nicotinic acetylcholine receptors and growth factor receptor-activated pathways offers a novel mechanism by which nicotine may directly impinge on cell cycle progression. This offers insight into possible reasons that underlie the unique effects of nicotine on distinct cell types and identifies new targets that may be useful control tobacco-related diseases.

  11. Baseline impulsive choice predicts the effects of nicotine and nicotine withdrawal on impulsivity in rats.

    Science.gov (United States)

    Kayir, Hakan; Semenova, Svetlana; Markou, Athina

    2014-01-03

    Impulsive choice, a form of impulsivity, is associated with tobacco smoking in humans. Trait impulsivity may be a vulnerability factor for smoking, or smoking may lead to impulsive behaviors. We investigated the effects of 14-day nicotine exposure (6.32mg/kg/day base, subcutaneous minipumps) and spontaneous nicotine withdrawal on impulsive choice in low impulsive (LI) and high impulsive (HI) rats. Impulsive choice was measured in the delayed reward task in which rats choose between a small immediate reward and a large delayed reward. HI and LI rats were selected from the highest and lowest quartiles of the group before exposure to nicotine. In non-selected rats, nicotine or nicotine withdrawal had no effect on impulsive choice. In LI rats, chronic nicotine exposure decreased preference for the large reward with larger effects at longer delays, indicating increased impulsive choice. Impulsive choices for the smaller immediate rewards continued to increase during nicotine withdrawal in LI rats. In HI rats, nicotine exposure and nicotine withdrawal had no effect on impulsive choice, although there was a tendency for decreased preference for the large reward at short delays. These results indicate that nicotine- and nicotine withdrawal-induced increases in impulsive choice depend on trait impulsivity with more pronounced increases in impulsive choice in LI compared to HI subjects. Increased impulsivity during nicotine exposure may strengthen the addictive properties of nicotine and contribute to compulsive nicotine use. © 2013.

  12. Effects of combined nicotine and fluoxetine treatment on adult hippocampal neurogenesis and conditioned place preference.

    Science.gov (United States)

    Faillace, M P; Zwiller, J; Bernabeu, R O

    2015-08-06

    Adult neurogenesis occurs in mammals within the dentate gyrus, a hippocampal subarea. It is known to be induced by antidepressant treatment and reduced in response to nicotine administration. We checked here whether the antidepressant fluoxetine would inverse the decrease in hippocampal neurogenesis caused by nicotine. It is shown that repeated, but not a single injection of rats with fluoxetine was able to abolish the decrease in adult dentate cell proliferation produced by nicotine treatment. We measured the expression of several biochemical parameters known to be associated with neurogenesis in the dentate gyrus. Both drugs increased the expression of p75 neurotrophin receptor, which promotes proliferation and early maturation of dentate gyrus cells. Using the conditioned place preference (CPP) paradigm, we also gave both drugs in a context in which their rewarding properties could be measured. Fluoxetine produced a significant but less robust CPP than nicotine. A single injection of fluoxetine was found to reduce nicotine-induced CPP. Moreover, the rewarding properties of nicotine were completely abolished in response to repeated fluoxetine injections. Expression of nicotine-induced CPP was accompanied by an increase of phospho-CREB (cyclic AMP-responsive element-binding protein) and HDAC2 (histone deacetylase 2) expression in the nucleus accumbens. The data suggest that fluoxetine reward, as opposed to nicotine reward, depends on dentate gyrus neurogenesis. Since fluoxetine was able to disrupt the association between nicotine and the environment, this antidepressant may be tested as a treatment for nicotine addiction using cue exposure therapy. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  13. Anti-allergic role of cholinergic neuronal pathway via α7 nicotinic ACh receptors on mucosal mast cells in a murine food allergy model.

    Directory of Open Access Journals (Sweden)

    Takeshi Yamamoto

    Full Text Available The prevalence of food allergy (FA has increased in developed countries over the past few decades. However, no effective drug therapies are currently available. Therefore, we investigated cholinergic anti-inflammatory pathway as a regulatory system to ameliorate disrupted mucosal immune homeostasis in the gut based on the pathophysiological elucidation of mucosal mast cells (MMCs in a murine FA model. BALB/c mice sensitized with ovalbumin received repeated oral ovalbumin for the development of FA. FA mice developed severe allergic diarrhea and exhibited enhanced type 2 helper T (Th2 cell immune responses in both systemic immunity and mucosal immunity, along with MMCs hyperplasia in the colon. MMCs were localized primarily in the strategic position of the mucosal epithelium. Furthermore, the allergic symptoms did not develop in p85α disrupted phosphoinositide-3 kinase-deficient mice that lacked mast cells in the gut. Vagal stimulation by 2-deoxy-D-glucose and drug treatment with nicotinic ACh receptor (nAChR agonists (nicotine and α7 nAChR agonist GTS-21 alleviated the allergic symptoms in the FA mice. Nicotine treatment suppressed MMCs hyperplasia, enhanced MPO and upregulated mRNA expression of Th1 and Th2 cytokines in the FA mice colon. MMCs, which are negatively regulated by α7 nAChRs, were often located in close proximity to cholinergic CGRP-immunoreactive nerve fibers in the FA mice colon. The present results reveal that the cholinergic neuroimmune interaction via α7 nAChRs on MMCs is largely involved in maintaining intestinal immune homeostasis and can be a target for a new therapy against mucosal immune diseases with homeostatic disturbances such as FA.

  14. Interaction of alpha-conotoxin ImII and its analogs with nicotinic receptors and acetylcholine-binding proteins: additional binding sites on Torpedo receptor.

    Science.gov (United States)

    Kasheverov, Igor E; Zhmak, Maxim N; Fish, Alexander; Rucktooa, Prakash; Khruschov, Alexey Yu; Osipov, Alexey V; Ziganshin, Rustam H; D'hoedt, Dieter; Bertrand, Daniel; Sixma, Titia K; Smit, August B; Tsetlin, Victor I

    2009-11-01

    alpha-Conotoxins interact with nicotinic acetylcholine receptors (nAChRs) and acetylcholine-binding proteins (AChBPs) at the sites for agonists/competitive antagonists. alpha-Conotoxins blocking muscle-type or alpha7 nAChRs compete with alpha-bungarotoxin. However, alpha-conotoxin ImII, a close homolog of the alpha7 nAChR-targeting alpha-conotoxin ImI, blocked alpha7 and muscle nAChRs without displacing alpha-bungarotoxin (Ellison et al. 2003, 2004), suggesting binding at a different site. We synthesized alpha-conotoxin ImII, its ribbon isomer (ImIIiso), 'mutant' ImII(W10Y) and found similar potencies in blocking human alpha7 and muscle nAChRs in Xenopus oocytes. Both isomers displaced [(125)I]-alpha-bungarotoxin from human alpha7 nAChRs in the cell line GH(4)C(1) (IC(50) 17 and 23 microM, respectively) and from Lymnaea stagnalis and Aplysia californica AChBPs (IC(50) 2.0-9.0 microM). According to SPR measurements, both isomers bound to immobilized AChBPs and competed with AChBP for immobilized alpha-bungarotoxin (K(d) and IC(50) 2.5-8.2 microM). On Torpedo nAChR, alpha-conotoxin [(125)I]-ImII(W10Y) revealed specific binding (K(d) 1.5-6.1 microM) and could be displaced by alpha-conotoxin ImII, ImIIiso and ImII(W10Y) with IC(50) 2.7, 2.2 and 3.1 microM, respectively. As alpha-cobratoxin and alpha-conotoxin ImI displaced [(125)I]-ImII(W10Y) only at higher concentrations (IC(50)> or = 90 microM), our results indicate that alpha-conotoxin ImII and its congeners have an additional binding site on Torpedo nAChR distinct from the site for agonists/competitive antagonists.

  15. Monoclonal antibodies against synthetic sequences of the nicotinic receptor cross-react fully with the native receptor and reveal the transmembrane disposition of their epitopes.

    Science.gov (United States)

    Lei, S; Raftery, M A; Conti-Tronconi, B M

    1993-01-12

    Monoclonal antibodies (mAbs) were derived from mice immunized with synthetic peptide sequence regions of the alpha subunit of the nicotinic acetylcholine receptor from Torpedo electric tissue (TAChR). Sequence-specific mAbs were obtained against the following peptides: alpha 1-20, alpha 291-308, alpha 304-322, alpha 332-350, alpha 346-364, alpha 360-378, alpha 376-393, alpha 390-409, and alpha 420-437. The ability of mAbs to recognize native TAChR was quantitated by immunoprecipitation of TAChR solubilized in the nondenaturing detergent Triton X-100. mAbs against peptide alpha 304-322, alpha 332-350, and alpha 360-378 cross-reacted with most or all Triton-solubilized TAChR molecules and, in immunoelectron microscopy experiments, bound to the cytoplasmic surface of AChR-rich postsynaptic membrane fragments. Two mAbs specific for the sequence alpha 376-393, proposed to form an amphypathic alpha helix possibly involved in formation of the ion channel, recognized only approximately 35% of Triton-solubilized TAChR molecules and did not react with membrane-bound TAChR. All of these sequence-specific antibodies recognized SDS-denatured TAChR alpha subunit in Western blots. MAbs specific for the amino-terminal sequence region of the alpha subunit, alpha 1-20, and for the sequences alpha 291-308, alpha 346-364, and alpha 390-409 did not recognize native TAChR. A mAb directed against the carboxyl-terminal region, alpha 420-437, recognized with low apparent titer Triton-solubilized TAChR, not membrane-bound TAChR. In conclusion, a complex membrane protein, TAChR, contains several continuous sequence segments exposed on the TAChR surface, because different mAbs raised against certain synthetic sequences recognized most or all native TAChR molecules. By analogy, it should be possible for most proteins of known sequence to raise anti-peptide antibodies fully cross-reactive with the native cognate protein.

  16. Nicotinic acetylcholine receptor subunit variants are associated with blood pressure; findings in the Old Order Amish and replication in the Framingham Heart Study

    Directory of Open Access Journals (Sweden)

    Ott Sandy

    2008-07-01

    Full Text Available Abstract Background Systemic blood pressure, influenced by both genetic and environmental factors, is regulated via sympathetic nerve activity. We assessed the role of genetic variation in three subunits of the neuromuscular nicotinic acetylcholine receptor positioned on chromosome 2q, a region showing replicated evidence of linkage to blood pressure. Methods We sequenced CHRNA1, CHRND and CHRNG in 24 Amish subjects from the Amish Family Diabetes Study (AFDS and identified 20 variants. We then performed association analysis of non-redundant variants (n = 12 in the complete AFDS cohort of 1,189 individuals, and followed by genotyping blood pressure-associated variants (n = 5 in a replication sample of 1,759 individuals from the Framingham Heart Study (FHS. Results The minor allele of a synonymous coding SNP, rs2099489 in CHRNG, was associated with higher systolic blood pressure in both the Amish (p = 0.0009 and FHS populations (p = 0.009 (minor allele frequency = 0.20 in both populations. Conclusion CHRNG is currently thought to be expressed only during fetal development. These findings support the Barker hypothesis, that fetal genotype and intra-uterine environment influence susceptibility to chronic diseases later in life. Additional studies of this variant in other populations, as well as the effect of this variant on acetylcholine receptor expression and function, are needed to further elucidate its potential role in the regulation of blood pressure. This study suggests for the first time in humans, a possible role for genetic variation in the neuromuscular nicotinic acetylcholine receptor, particularly the gamma subunit, in systolic blood pressure regulation.

  17. Subchronic exposure to sublethal dose of imidacloprid changes electrophysiological properties and expression pattern of nicotinic acetylcholine receptor subtypes in insect neurosecretory cells.

    Science.gov (United States)

    Benzidane, Yassine; Goven, Delphine; Abd-Ella, Aly Ahmed; Deshayes, Caroline; Lapied, Bruno; Raymond, Valérie

    2017-09-01

    Neonicotinoids are the most important class of insecticides used in agriculture over the last decade. They act as selective agonists of insect nicotinic acetylcholine receptors (nAChRs). The emergence of insect resistance to these insecticides is one of the major problems, which limit the use of neonicotinoids. The aim of our study is to better understand physiological changes appearing after subchronic exposure to sublethal doses of insecticide using complementary approaches that include toxicology, electrophysiology, molecular biology and calcium imaging. We used cockroach neurosecretory cells identified as dorsal unpaired median (DUM) neurons, known to express two α-bungarotoxin-insensitive (α-bgt-insensitive) nAChR subtypes, nAChR1 and nAChR2, which differ in their sensitivity to imidacloprid. Although nAChR1 is sensitive to imidacloprid, nAChR2 is insensitive to this insecticide. In this study, we demonstrate that subchronic exposure to sublethal dose of imidacloprid differentially changes physiological and molecular properties of nAChR1 and nAChR2. Our findings reported that this treatment decreased the sensitivity of nAChR1 to imidacloprid, reduced current density flowing through this nAChR subtype but did not affect its subunit composition (α3, α8 and β1). Subchronic exposure to sublethal dose of imidacloprid also affected nAChR2 functions. However, these effects were different from those reported on nAChR1. We observed changes in nAChR2 conformational state, which could be related to modification of the subunit composition (α1, α2 and β1). Finally, the subchronic exposure affecting both nAChR1 and nAChR2 seemed to be linked to the elevation of the steady-state resting intracellular calcium level. In conclusion, under subchronic exposure to sublethal dose of imidacloprid, cockroaches are capable of triggering adaptive mechanisms by reducing the participation of imidacloprid-sensitive nAChR1 and by optimizing functional properties of nAChR2, which is

  18. Alpha-7 nicotinic acetylcholine receptor agonist treatment reduces neuroinflammation, oxidative stress, and brain injury in mice with ischemic stroke and bone fracture.

    Science.gov (United States)

    Han, Zhenying; Li, Li; Wang, Liang; Degos, Vincent; Maze, Mervyn; Su, Hua

    2014-11-01

    Bone fracture at the acute stage of stroke exacerbates stroke injury by increasing neuroinflammation. We hypothesize that activation of α-7 nicotinic acetylcholine receptor (α-7 nAchR) attenuates neuroinflammation and oxidative stress, and reduces brain injury in mice with bone fracture and stroke. Permanent middle cerebral artery occlusion (pMCAO) was performed in C57BL/6J mice followed by tibia fracture 1 day later. Mice were treated with 0.8 mg/kg PHA 568487 (PHA, α-7 nAchR-specific agonist), 6 mg/kg methyllycaconitine (α-7 nAchR antagonist), or saline 1 and 2 days after pMCAO. Behavior was tested 3 days after pMCAO. Neuronal injury, CD68(+) , M1 (pro-inflammatory) and M2 (anti-inflammatory) microglia/macrophages, phosphorylated p65 component of nuclear factor kappa b in microglia/macrophages, oxidative and anti-oxidant gene expression were quantified. Compared to saline-treated mice, PHA-treated mice performed better in behavioral tests, had fewer apoptotic neurons (NeuN(+) TUNEL(+) ), fewer CD68(+) and M1 macrophages, and more M2 macrophages. PHA increased anti-oxidant gene expression and decreased oxidative stress and phosphorylation of nuclear factor kappa b p65. Methyllycaconitine had the opposite effects. Our data indicate that α-7 nAchR agonist treatment reduces neuroinflammation and oxidative stress, which are associated with reduced brain injury in mice with ischemic stroke plus tibia fracture. Bone fracture at the acute stage of stroke exacerbates neuroinflammation, oxidative stress, and brain injury, and our study has shown that the α-7 nAchR agonist, PHA (PHA 568487), attenuates neuroinflammation, oxidative stress, and brain injury in mice with stroke and bone fracture. Hence, PHA could provide an opportunity to develop a new strategy to reduce brain injury in patients suffering from stroke and bone fracture. © 2014 International Society for Neurochemistry.

  19. Pineal and cortical melatonin receptors MT1 and MT2 are decreased in Alzheimer's disease.

    Science.gov (United States)

    Brunner, P; Sözer-Topcular, N; Jockers, R; Ravid, R; Angeloni, D; Fraschini, F; Eckert, A; Müller-Spahn, F; Savaskan, E

    2006-01-01

    The pineal hormone melatonin is involved in physiological transduction of temporal information from the light dark cycle to circadian and seasonal behavioural rhythms, as well as possessing neuroprotective properties. Melatonin and its receptors MT1 and MT2, which belong to the family of G protein-coupled receptors, are impaired in Alzheimer's disease (AD) with severe consequences to neuropathology and clinical symptoms. The present data provides the first immunohistochemical evidence for the cellular localization of the both melatonin receptors in the human pineal gland and occipital cortex, and demonstrates their alterations in AD. We localized MT1 and MT2 in the pineal gland and occipital cortex of 7 elderly controls and 11 AD patients using immunohistochemistry with peroxidase-staining. In the pineal gland both MT1 and MT2 were localized to pinealocytes, whereas in the cortex both receptors were expressed in some pyramidal and non-pyramidal cells. In patients with AD, parallel to degenerative tissue changes, there was an overall decrease in the intensity of receptors in both brain regions. In line with our previous findings, melatonin receptor expression in AD is impaired in two additional brain areas, and may contribute to disease pathology.

  20. Chronic Nicotine Treatment During Adolescence Attenuates the Effects of Acute Nicotine in Adult Contextual Fear Learning.

    Science.gov (United States)

    Holliday, Erica D; Gould, Thomas J

    2017-01-01

    Adolescent onset of nicotine abuse is correlated with worse chances at successful abstinence in adulthood. One reason for this may be due to enduring learning deficits resulting from nicotine use during adolescence. Previous work has indicated that chronic nicotine administration beginning in late adolescence (PND38) caused learning deficits in contextual fear when tested in adulthood. The purpose of this study was to determine if chronic nicotine treatment during adolescence would alter sensitivity to nicotine's cognitive enhancing properties in adulthood. C57BL/6J mice received saline or chronic nicotine (12.6mg/kg/day) during adolescence (postnatal day 38) or adulthood (postnatal day 54) for a period of 12 days. Following a 30-day protracted abstinence, mice received either an acute injection of saline or nicotine (0.045, 0.18, and 0.36mg/kg) prior to training and testing a mouse model of contextual fear. It was found that chronic nicotine administration in adult mice did not alter sensitivity to acute nicotine following a protracted abstinence. In adolescent mice, chronic nicotine administration disrupted adult learning and decreased sensitivity to acute nicotine in adulthood as only the highest dose tested (0.36mg/kg) was able to enhance contextual fear learning. These results suggest that adolescent nicotine exposure impairs learning in adulthood, which could increase the risk for continued nicotine use in adulthood by requiring administration of higher doses of nicotine to reverse learning impairments caused by adolescent nicotine exposure. Results from this study add to the growing body of literature suggesting chronic nicotine exposure during adolescence leads to impaired learning in adulthood and demonstrates that nicotine exposure during adolescence attenuates the cognitive enhancing effects of acute nicotine in adulthood, which suggests altered cholinergic function. © The Author 2016. Published by Oxford University Press on behalf of the Society for

  1. Evaluation of [18F]-(−)-Norchlorofluorohomoepibatidine ([18F]-(−)-NCFHEB) as a PET Radioligand to Image the Nicotinic Acetylcholine Receptors in Non-human Primates

    Science.gov (United States)

    Bois, Frederic; Gallezot, Jean-Dominique; Zheng, Ming-Qiang; Lin, Shu-Fei; Esterlis, Irina; Cosgrove, Kelly P.; Carson, Richard E.; Huang, Yiyun

    2015-01-01

    Introduction The aims of the present study were to develop an optimized microfluidic method for the production of the selective nicotinic acetylcholine α4β2 receptor radiotracer [18F]-(−)-NCFHEB ([18F]-Flubatine) and to investigate its receptor binding profile and pharmacokinetic properties in rhesus monkeys in vivo. Methods [18F]-(−)-NCFHEB was prepared in two steps, a nucleophilic fluorination followed by N-Boc deprotection. PET measurements were performed in rhesus monkeys including baseline and preblocking experiments with nicotine (0.24 mg/kg). Radiometabolites in plasma were measured using HPLC. Results [18F]-(−)-NCFHEB was prepared in a total synthesis time of 140 min. The radiochemical purity in its final formulation was >98% and the mean specific radioactivity was 97.3 ± 16.1Bq/μmol (n = 6) at end of synthesis (EOS). In the monkey brain, radioactivity concentration was high in the thalamus, moderate in the putamen, hippocampus, frontal cortex, and lower in the cerebellum. Nicotine blocked 98–100% of [18F]-(−)-NCFHEB specific binding, and the non-displaceable distribution volume (VND) was estimated at 5.9 ± 1.0 mL/cm3 (n = 2), or 6.6 ± 1.1 mL/cm3 after normalization by the plasma free fraction fP. Imaging data are amenable to kinetic modeling analysis using the multilinear analysis (MA1) method, and model-derived binding parameters display good test-retest reproducibility. In rhesus monkeys, [18F]-(−)-NCFHEB can yield robust regional binding potential (BPND) values (thalamus = 4.1 ± 1.5, frontal cortex = 1.2 ± 0.2, putamen = 0.96 ± 0.45, cerebellum = 0.10 ± 0.29). Conclusion An efficient microfluidic synthetic method was developed for preparation of [18F]-(−)-NCFHEB. PET examination in rhesus monkeys showed that [18F]-(−)-NCFHEB entered the brain readily and its regional radioactivity uptake pattern was in accordance with the known distribution of α4β2 receptors. Estimated non-displaceable binding potential (BPND) values in brain

  2. Premature aging phenotype in mice lacking high affinity nicotinic receptors: region specific changes in layer V pyramidal cell morphology

    Directory of Open Access Journals (Sweden)

    Eleni Konsolaki

    2014-02-01

    Full Text Available The mechanisms by which aging leads to alterations in brain structure and cognitive deficits are unclear. A central yet presently unresolved issue in aging research concerns the distinction between normal/successful aging, consisting of a moderate decline in cognitive performance, and pathological aging, manifested as mild cognitive impairment or full-blown neurodegeneration and dementia. In particular, it has been proposed that the age-related decline in cognitive abilities may be an age-related escalation of early-life cognitive limitations, rather than an abruptly emerging neuropathological process that occurs in old age (Elias et al., 2000; Small et al., 2000; Sarter and Bruno, 2004; Amieva et al., 2005; Tyas et al., 2007. In this scenario, early abnormalities or incompletely matured neural systems would interact with age-related processes to explain the cognitive decline in later ages. However this proposal remains controversial (Nilsson et al., 2009; Salthouse, 2009 and, to our knowledge, has not been explored at the morphological/structural level. Hence it is important to identify factors that may confer a predisposition to pathological aging and examine how they interact with the process of aging per se. One such factor is the integrity of the cholinergic system: cholinergic basal forebrain neurons and their projections to the cortex show increased vulnerability to aging (Fischer et al., 1987; Altavista et al., 1990; Casu et al., 2002 and cognitive decline is associated with selective loss of neuronal nicotinic acetylcholine receptor (nAChR function (Hellstrom-Lindahl and Court, 2000; Schliebs and Arendt, 2011. In this respect, animals with specific cholinergic deficits are important tools for understanding the neurobiology of successful aging. One such animal model is the β2-/- mouse, in which the gene encoding the β2 subunit of the nAChR is genetically deleted (Picciotto et al., 1995. Aged β2-/- mice have been proposed as a model of

  3. Synthesis and evaluation of 6-[{sup 18}F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine as a PET tracer for nicotinic acetylcholine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Y.-S. E-mail: ding@bnl.gov; Liu, N.; Wang, T.; Marecek, J.; Garza, V.; Ojima, I.; Fowler, J.S

    2000-05-01

    Both ABT-594 ((R)-2-chloro-5-(2-azetidinylmethoxy)pyridine) and A-85380 (3-[2(S)-2-azetidinylmethoxy]pyridine), novel nicotinic agonists that possess potent non-opioid analgesic properties, have high affinity for neuronal nicotinic acetylcholine receptors (nAChR) but do not elicit the pronounced toxicity of epibatidine. 6-[{sup 18}F]Fluoro-3-(2(S)-azetidinylmethoxy)pyridine (6-[{sup 18}F]fluoro-A-85380), a F-18 labeled analogue of these two compounds, is therefore a promising radioligand for positron emission tomography (PET) studies in humans. The use of trimethylammonium as a leaving group in nucleophilic aromatic substitution reactions has proven to be a versatile and efficient strategy, and offers several advantages over other leaving groups. Here, we report the synthetic strategy for the preparation of a precursor, as a trimethylammonium iodide salt, and its use in the radiosynthesis to 6-[{sup 18}F]fluoro-A-85380. Preliminary comparative PET studies of 6-[{sup 18}F]fluoro-A-85380 and 2-[{sup 18}F]fluoro-A-85380 were carried out in baboon to examine their suitability as tracers for studying nAChR system.

  4. 5-[I-125/123]lodo-3(2(S)-azetidinylmethoxy)pyridine, a radioiodinated analog of A-85380 for in vivo studies of central nicotinic acetylcholine receptors.

    Science.gov (United States)

    Musachio, J L; Scheffel, U; Finley, P A; Zhan, Y; Mochizuki, T; Wagner, H N; Dannals, R F

    1998-01-01

    The in vivo biodistribution profile of the novel nicotinic acetylcholine receptor (nAChR) radioligand 5-[I-125/123]Iodo-3(2(S)-azetidinylmethoxy)pyridine, [I-125/123]-5-IA, in mouse brain was examined. This radiotracer displayed good brain penetration (3.1% of the injected dose (ID) in whole brain at 15 min post-radioligand injection). Radioligand distribution was consistent with the density of high affinity nAChRs with highest uptake observed in the nAChR-rich thalamus (14.9 %ID/g at 60 min), moderate uptake in cortex (8.5 %ID/g at 60 min), and lowest uptake in the cerebellum (2.4 %ID/g at 60 min). Pretreatment with several different nAChR agonists (A-85380, (-)-nicotine, cytisine) significantly inhibited [I-125]-5-IA binding in all brain regions studied (P 3 mg/kg via intravenous injection in mice) and high in vivo specificity and selectivity, 5-IA labeled with the imaging radionuclide I-123 may prove useful for single photon emission computed tomography (SPECT) studies of nAChRs in human subjects.

  5. Nicotine Increases Impulsivity and Decreases Willingness to Exert Cognitive Effort despite Improving Attention in “Slacker” Rats: Insights into Cholinergic Regulation of Cost/Benefit Decision Making

    OpenAIRE

    Hosking, Jay G.; Lam, Fred C. W.; Winstanley, Catharine A

    2014-01-01

    Successful decision making in our daily lives requires weighing an option's costs against its associated benefits. The neuromodulator acetylcholine underlies both the etiology and treatment of a number of illnesses in which decision making is perturbed, including Alzheimer's disease, attention-deficit/hyperactivity disorder, and schizophrenia. Nicotine acts on the cholinergic system and has been touted as a cognitive enhancer by both smokers and some researchers for its attention-boosting eff...

  6. Localized infusions of the partial alpha 7 nicotinic receptor agonist SSR180711 evoke rapid and transient increases in prefrontal glutamate release

    DEFF Research Database (Denmark)

    Bortz, D M; Mikkelsen, J D; Bruno, J P

    2013-01-01

    that inhibited (threo-beta-benzyl-oxy-aspartate (TβOA), 100.0μM) or facilitated (ceftriaxalone, 200mg/kg, i.p.) excitatory amino acid transporters. TβOA slowed both the clearance (s) and rate of clearance (μM/s) by 10-fold, particularly at the mid-late stages of the return to baseline. Ceftriaxone reduced......The ability of local infusions of the alpha 7 nicotinic acetycholine receptor (α7 nAChR) partial agonist SSR180711 to evoke glutamate release in prefrontal cortex was determined in awake rats using a microelectrode array. Infusions of SSR180711 produced dose-dependent increases in glutamate levels...

  7. Dimensions of the ion channel in neuronal nicotinic acetylcholine receptor as estimated from analysis of conformation-activity relationships of open-channel blocking drugs.

    Science.gov (United States)

    Zhorov, B S; Brovtsyna, N B; Gmiro, V E; Lukomskaya NYa; Serdyuk, S E; Potapyeva, N N; Magazanik, L G; Kurenniy, D E; Skok, V I

    1991-04-01

    Relationship between the size of the molecule in the series of organic ions Et3+N--(CH2)5--+NR1R2R3 (Ri--alkyl or cycloalkyl substituents) and their abilities to block nicotinic acetylcholine receptors (AChRs) due to their open-channel blockade in the neurons of autonomic ganglia and in frog end-plate was analyzed. All low-energy equilibrium conformations of the drugs were calculated by the molecular mechanics method. A unique rectangular channel profile 6.1 x 8.3 A, for which the best correlation between blocking activity of the drugs and total population of their conformations being able to penetrate into the channel, was deduced from all those tested.

  8. a7 nicotinic receptor agonism mitigates phencyclidine-induced changes in synaptophysin and Arc gene expression in the mouse prefrontal cortex

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hansen, Henrik H; Mikkelsen, Jens D

    2010-01-01

    (10 mg/kg/day for 10 days) is able to mitigate the reduction of synaptophysin mRNA expression induced by PCP in two prefrontal cortical regions, the medial prefrontal cortex (mPFC) and the ventrolateral orbitofrontal cortex (VLO). This effect is accompanied by a normalization of the PCP......Repeated phencyclidine (PCP) administration in mice reproduces several histopathological features of schizophrenia, such as reduced synaptophysin and parvalbumin mRNA expression in the frontal cortex. These changes can be prevented by co-administering the a7 nicotinic acetylcholine receptor (n...... of synaptophysin and/or Arc levels in the frontal cortex. These data lend support to the potential for development of a7 nAChR agonists for the treatment of cognitive deficits in schizophrenia....

  9. α7 nicotinic receptor agonism mitigates phencyclidine-induced changes in synaptophysin and Arc gene expression in the mouse prefrontal cortex

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hansen, Henrik H; Mikkelsen, Jens D

    2010-01-01

    (10 mg/kg/day for 10 days) is able to mitigate the reduction of synaptophysin mRNA expression induced by PCP in two prefrontal cortical regions, the medial prefrontal cortex (mPFC) and the ventrolateral orbitofrontal cortex (VLO). This effect is accompanied by a normalization of the PCP......Repeated phencyclidine (PCP) administration in mice reproduces several histopathological features of schizophrenia, such as reduced synaptophysin and parvalbumin mRNA expression in the frontal cortex. These changes can be prevented by co-administering the α7 nicotinic acetylcholine receptor (n...... of synaptophysin and/or Arc levels in the frontal cortex. These data lend support to the potential for development of α7 nAChR agonists for the treatment of cognitive deficits in schizophrenia....

  10. Estimating binding affinities of the nicotinic receptor for low-efficacy ligands using mixtures of agonists and two-dimensional concentration-response relationships.

    Science.gov (United States)

    Purohit, Yamini; Grosman, Claudio

    2006-06-01

    The phenomenon of ligand-induced ion channel gating hinges upon the ability of a receptor channel to bind ligand molecules with conformation-specific affinities. However, our understanding of this fundamental phenomenon is notably limited, not only because the changes in binding site structure and ligand conformation that occur upon gating are largely unknown but, also, because the strength of these ligand-receptor interactions are experimentally elusive. Both high- and low-efficacy ligands pose a number of analytical and experimental challenges that can render the estimation of their conformation-specific binding affinities impossible. In this paper, we present a novel assay that overcomes some of the hurdles presented by weak agonists of the muscle nicotinic receptor and allows the estimation of their closed-state affinities. The method, which we have termed the "activation-competition" assay, consists of a single-channel concentration-response assay performed in the presence of a binary mixture of ligands of widely different efficacies. By plotting the channel response (i.e., the open probability) as a function of the concentration of each agonist in the mixture, interpreting the observed response in the framework of a plausible kinetic scheme, and fitting the open probability surface with the corresponding function, the affinities of the closed receptor for the two agonists can be simultaneously extracted as free parameters. Here, we applied this methodology to estimate the closed-state affinity of the muscle nicotinic receptor for choline (a very weak agonist) using acetylcholine (ACh) as the partner in the mixture. We estimated the dissociation equilibrium constant of choline (K(D)) from the wild type's closed state to be 4.1 +/- 0.5 mM (and that of ACh to be 106 +/- 6 microM). We also discuss the use of accurate estimates of affinities for low-efficacy agonists as a tool to discriminate between binding and gating effects of mutations, and in the context of

  11. Nicotine and the adolescent brain

    Science.gov (United States)

    Yuan, Menglu; Cross, Sarah J; Loughlin, Sandra E; Leslie, Frances M

    2015-01-01

    Adolescence encompasses a sensitive developmental period of enhanced clinical vulnerability to nicotine, tobacco, and e-cigarettes. While there are sociocultural influences, data at preclinical and clinical levels indicate that this adolescent sensitivity has strong neurobiological underpinnings. Although definitions of adolescence vary, the hallmark of this period is a profound reorganization of brain regions necessary for mature cognitive and executive function, working memory, reward processing, emotional regulation, and motivated behavior. Regulating critical facets of brain maturation are nicotinic acetylcholine receptors (nAChRs). However, perturbations of cholinergic systems during this time with nicotine, via tobacco or e-cigarettes, have unique consequences on adolescent development. In this review, we highlight recent clinical and preclinical data examining the adolescent brain's distinct neurobiology and unique sensitivity to nicotine. First, we discuss what defines adolescence before reviewing normative structural and neurochemical alterations that persist until early adulthood, with an emphasis on dopaminergic systems. We review how acute exposure to nicotine impacts brain development and how drug responses differ from those seen in adults. Finally, we discuss the persistent alterations in neuronal signaling and cognitive function that result from chronic nicotine exposure, while highlighting a low dose, semi-chronic exposure paradigm that may better model adolescent tobacco use. We argue that nicotine exposure, increasingly occurring as a result of e-cigarette use, may induce epigenetic changes that sensitize the brain to other drugs and prime it for future substance abuse. PMID:26018031

  12. Nicotine and the adolescent brain.

    Science.gov (United States)

    Yuan, Menglu; Cross, Sarah J; Loughlin, Sandra E; Leslie, Frances M

    2015-08-15

    Adolescence encompasses a sensitive developmental period of enhanced clinical vulnerability to nicotine, tobacco, and e-cigarettes. While there are sociocultural influences, data at preclinical and clinical levels indicate that this adolescent sensitivity has strong neurobiological underpinnings. Although definitions of adolescence vary, the hallmark of this period is a profound reorganization of brain regions necessary for mature cognitive and executive function, working memory, reward processing, emotional regulation, and motivated behavior. Regulating critical facets of brain maturation are nicotinic acetylcholine receptors (nAChRs). However, perturbations of cholinergic systems during this time with nicotine, via tobacco or e-cigarettes, have unique consequences on adolescent development. In this review, we highlight recent clinical and preclinical data examining the adolescent brain's distinct neurobiology and unique sensitivity to nicotine. First, we discuss what defines adolescence before reviewing normative structural and neurochemical alterations that persist until early adulthood, with an emphasis on dopaminergic systems. We review how acute exposure to nicotine impacts brain development and how drug responses differ from those seen in adults. Finally, we discuss the persistent alterations in neuronal signaling and cognitive function that result from chronic nicotine exposure, while highlighting a low dose, semi-chronic exposure paradigm that may better model adolescent tobacco use. We argue that nicotine exposure, increasingly occurring as a result of e-cigarette use, may induce epigenetic changes that sensitize the brain to other drugs and prime it for future substance abuse. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  13. The Corticofugal Effects of Auditory Cortex Microstimulation on Auditory Nerve and Superior Olivary Complex Responses Are Mediated via Alpha-9 Nicotinic Receptor Subunit.

    Directory of Open Access Journals (Sweden)