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Sample records for a7 nicotinic receptor

  1. Activation of a7 Nicotinic Acetylcholine Receptors Prevents Monosodium Iodoacetate-Induced Osteoarthritis in Rats

    Directory of Open Access Journals (Sweden)

    Yuan Liu

    2015-01-01

    Full Text Available Background/Aims: Although some evidence suggests that the prevalence of osteoarthritis (OA is lower in smokers compared to nonsmokers, the mechanisms of nicotine-induced protection remain unclear. Stimulation of the a7 nicotinic acetylcholine receptor (a7-nAChR appears to be a critical mechanism underlying the anti-inflammatory potential of cholinergic agonists in immune cells. The inhibition of secreted inflammatory molecules and the subsequent inflammatory processes have been proposed as a novel strategy for the treatment of OA. The objective of the present study was to determine whether nicotine-induced protection in a monosodium iodoacetate (MIA rat model of OA occurs via a7-nAChR-mediated inhibition of chondrocytes. Methods: Both in vivo (MIA and in vitro (MIA; Interleukin-1ß, IL-1ß models of OA were used to investigate the roles and the possible mechanisms whereby a7-nAChRs protect against knee joint degradation. Multiple experimental approaches, including macroscopic, histological analysis, chondrocyte cell cultures, confocal microscopy, and western blotting, were employed to elucidate the mechanisms of a7-nAChR-mediated protection. Results: Systemic administration of nicotine alleviated MIA-induced joint degradation. The protective effects of nicotine were abolished by administration of the a7-nAChR-selective antagonist methyllycaconitine (MLA. In primary cultured rat chondrocytes, pretreatment with nicotine suppressed both p38, extracellular regulated kinase (Erk 1/2 and c-Jun-N-terminal kinase (JNK mitogen-activated protein kinases (MAPK phosphorylation and phosphorylated nuclear factor-kappa B (NF-κB p65 activation induced by MIA- or IL-1ß, and these effects were also reversed by MLA. Conclusion: Taken together, our results suggest that activation a7-nAChRs is an important mechanism underlying the protective effects of nicotine.

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

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    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)....

  3. 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)....

  4. Rat neuronal nicotinic acetylcholine receptors containing a7 subunit: pharmacological properties of ligand binding and function

    Institute of Scientific and Technical Information of China (English)

    Yingxian XIAO; Galya R ABDRAKHMANOVA; Maryna BAYDYUK; Susan HERNANDEZ; Kenneth J KELLAR

    2009-01-01

    Aim: To compare pharmacological properties of heterologously expressed homomeric a7 nicotinic acetylcholine receptors (a.7 nAChRs) with those of native nAChRs containing a.7 subunit (a.7* nAChRs) in rat hippocampus and cerebral cortex. Methods: We established a stably transfected HEK-293 cell line that expresses homomeric rat a7 nAChRs. We studies ligand binding profiles and functional properties of nAChRs expressed in this cell line and native rat a.7* nAChRs in rat hippocampus and cerebral cortex. We used [125IJ-a-bungarotoxin to compare ligand binding profiles in these cells with those in rat hippocampus and cerebral cortex. The functional properties of the a.7 nAChRs expressed in this cell line were studied using whole-cell current recording.Results: The newly established cell line, KXa7Rl, expresses homomeric a7 nAChRs that bind [125I]-a-bungarotoxin with a Kd value of 0.38±0.06 nmol/L, similar to Kj values of native rat a.7* nAChRs from hippocampus (Kd=0.28±0.03 nmol/L) and cerebral cortex (Kd=0.33±0.05 nmol/L). Using whole-cell current recording, the homomeric a7 nAChRs expressed in the cells were activated by acetylcholine and (-)-nicotine with EC50 values of 280±19 nmol/L and 180±40 nmol/L, respectively. The acetylcholine activated currents were potently blocked by two selective antagonists of a.7 nAChRs, a-bungarotoxin (IC5o=19±2 nmol/L) and methyllycaconitine (IC50=100±10 pmol/L). A comparative study of ligand binding profiles, using 13 nicotinic ligands, showed many similarities between the homomeric a.7 nAChRs and native a.7* receptors in rat brain, but it also revealed several notable differences.Conclusion: This newly established stable cell line should be very useful for studying the properties of homomeric a7 nAChRs and comparing these properties to native a.7* nAChRs.

  5. 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

    Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels and belong to the superfamily of Cys-loop receptors. Valuable insight into the orthosteric ligand binding to nAChRs in recent years has been obtained from the crystal structures of acetylcholine binding proteins (ACh...

  6. The role of the a7 subunit of the nicotinic acetylcholine receptor in the acute toxicosis of methyllycaconitine in mice.

    Science.gov (United States)

    The adverse physiological effects of methyllycaconitine (MLA) have been attributed to its competitive antagonism of nicotinic acetylcholine receptors (nAChRs). Recent research demonstrated a correlation between the LD50 of MLA and the amount of a7 nAChR in various mouse strains, suggesting that mice...

  7. The role of the a7 subunit of the nicotinic acetylcholine receptor on motor coordination in mice treated with methyllcaconitine and anabasine

    Science.gov (United States)

    The adverse effects of methyllycaconitine (MLA) have been attributed to competitive antagonism of nicotinic acetylcholine receptors (nAChR). Research has indicated a correlation between the LD50 of MLA and the amount of a7 nAChR in various mouse strains, suggesting that mice with more a7 nAChR requi...

  8. Ric-3 chaperone-mediated stable cell-surface expression of the neuronal a7 nicotinic acetylcholine receptor in mammalian cells

    Institute of Scientific and Technical Information of China (English)

    Ana Sofia VALLfiS; Ana M ROCCAMO; Francisco J BARRANTES

    2009-01-01

    Aim: Studies of the a7-type neuronal nicotinic acetylcholine receptor (AChR), one of the receptor forms involved in many physiologically relevant processes in the central nervous system, have been hampered by the inability of this homomeric protein to assemble in most heterologous expression systems. In a recent study, it was shown that the chaperone Ric-3 is necessary for the maturation and functional expression of a7-type AChRs'11. The current work aims at obtaining and characterizing a cell line with high functional expression of the human a7 AChR.Methods: Ric-3 cDNA was incorporated into SHE-Pl-ha7 cells expressing the a7-type AChR. Functional studies were undertaken using single-channel patch-clamp recordings. Equilibrium and kinetic [125I]a-bungarotoxin binding assays, as well as fluorescence microscopy using fluorescent a-bungarotoxin, anti-a7 antibody, and GFP-a7 were performed on the new clone.Results: The human a7-type AChR was stably expressed in a new cell line, which we coined SHE-PI-ha7-Ric-3, by co-expression of the chaperone Ric-3. Cell-surface AChRs exhibited [125I]aBTX saturable binding with an apparent KD of about 55 nmol/L. Fluorescence microscopy revealed dispersed and micro-clustered AChR aggregates at the surface of SHE-PI-ha7-Ric-3 cells. Larger micron-sized clusters were observed in the absence of receptor-clustering proteins or upon aggregation with anti-a7 antibodies, hi contrast, chaperone-less SHE-PI-ha7 cells expressed only intracellular a.7 AChRs and failed to produce detectable single-channel currents.Conclusion: The production of a stable and functional cell line of neuroepithelial lineage with robust cell-surface expression of neuronal a7-type AChR, as reported here, constitutes an important advance in the study of homomeric receptors in mammalian cells.

  9. 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

    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......AChR) agonist SSR180711 with PCP, but it is not known to what extent PCP-induced changes can be normalized once they have already occurred. Here we use semi-quantitative in situ hybridization to show that repeated administration of SSR180711 (3 mg/kg b.i.d. for 5 days) subsequent to repeated PCP administration...... (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...

  10. 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.

  11. Nitrosamines as nicotinic receptor ligands

    OpenAIRE

    Schuller, Hildegard M

    2007-01-01

    Nitrosamines are carcinogens formed in the mammalian organism from amine precursors contained in food, beverages, cosmetics and drugs. The potent carcinogen, NNK, and the weaker carcinogen, NNN, are nitrosamines formed from nicotine. Metabolites of the nitrosamines react with DNA to form adducts responsible for genotoxic effects. We have identified NNK as a high affinity agonist for the alpha7 nicotinic acetylcholine receptor (α7nAChR) whereas NNN bound with high affinity to epibatidine-sensi...

  12. Nicotine-induced upregulation of nicotinic receptors: underlying mechanisms and relevance to nicotine addiction.

    Science.gov (United States)

    Govind, Anitha P; Vezina, Paul; Green, William N

    2009-10-01

    A major hurdle in defining the molecular biology of nicotine addiction has been characterizing the different nicotinic acetylcholine receptor (nAChR) subtypes in the brain and how nicotine alters their function. Mounting evidence suggests that the addictive effects of nicotine, like other drugs of abuse, occur through interactions with its receptors in the mesolimbic dopamine system, particularly ventral tegmental area (VTA) neurons, where nicotinic receptors act to modulate the release of dopamine. The molecular identity of the nicotinic receptors responsible for drug seeking behavior, their cellular and subcellular location and the mechanisms by which these receptors initiate and maintain addiction are poorly defined. In this commentary, we review how nicotinic acetylcholine receptors (nAChRs) are upregulated by nicotine exposure, the potential posttranslational events that appear to cause it and how upregulation is linked to nicotine addiction.

  13. 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

    ) 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...... data were synthesized. Several analogs exhibited significantly improved antagonist activity for the alpha(7) nAChR compared with WT-ImI. Binding interactions between the analogs and the alpha(7) nAChR were explored using a homology model of the amino-terminal domain based on a crystal structure...... of an acetylcholine-binding protein. Finally, a third series of refined analogs was synthesized based on modeling studies, which led to several analogs with refined pharmacological properties. Of the 96 individual alpha-conotoxin analogs synthesized, three displayed > or =10-fold increases in antagonist potency...

  14. Nitrosamines as nicotinic receptor ligands.

    Science.gov (United States)

    Schuller, Hildegard M

    2007-05-30

    Nitrosamines are carcinogens formed in the mammalian organism from amine precursors contained in food, beverages, cosmetics and drugs. The potent carcinogen, NNK, and the weaker carcinogen, NNN, are nitrosamines formed from nicotine. Metabolites of the nitrosamines react with DNA to form adducts responsible for genotoxic effects. We have identified NNK as a high affinity agonist for the alpha7 nicotinic acetylcholine receptor (alpha7nAChR) whereas NNN bound with high affinity to epibatidine-sensitive nAChRs. Diethylnitrosamine (DEN) bound to both receptors but with lower affinity. High levels of the alpha7nAChR were expressed in human small cell lung cancer (SCLC) cell lines and in hamster pulmonary neuroendocrine cells (PNECs), which serve as a model for the cell of origin of human SCLC. Exposure of SCLC or PNECs to NNK or nicotine increased expression of the alpha7nAChR and caused influx of Ca(2+), activation of PKC, Raf-1, ERK1/2, and c-myc, resulting in the stimulation of cell proliferation. Signaling via the alpha7nAChR was enhanced when cells were maintained in an environment of 10-15% CO(2) similar to that in the diseased lung. Hamsters with hyperoxia-induced pulmonary fibrosis developed neuroendocrine lung carcinomas similar to human SCLC when treated with NNK, DEN, or nicotine. The development of the NNK-induced tumors was prevented by green tea or theophylline. The beta-adrenergic receptor agonist, isoproterenol or theophylline blocked NNK-induced cell proliferation in vitro. NNK and nicotine-induced hyperactivity of the alpha7nAChR/RAF/ERK1/2 pathway thus appears to play a crucial role in the development of SCLC in smokers and could be targeted for cancer prevention.

  15. Nicotinic Receptor Activity Alters Synaptic Plasticity

    Directory of Open Access Journals (Sweden)

    John A. Dani

    2001-01-01

    Full Text Available Studies using specific agonists, antagonists, and lesions have shown that nicotinic cholinergic systems participate in attention, learning, and memory[1,2]. The nicotinic manipulations usually have the greatest influence on difficult tasks or on cognitively impaired subjects[2]. For example, Alzheimer's disease is characterized by a loss of cholinergic projections and nicotinic acetylcholine receptors (nAChRs in the cortex and hippocampus[3]. Nicotine skin patches can improve learning rates and attention in Alzheimer's patients[4].

  16. Alcohol and nicotinic acetylcholine receptors

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    Jinsong Tang

    2013-05-01

    Full Text Available Background The frequent co-abuse of alcohol and tobacco may suggest that they share some common neurological mechanisms. For example, nicotine acts on Nicotinic acetylcholine receptors (nAChRs in the brain to release dopamine to sustain addiction. Might nAChRs be entwined with alcohol? Objectives This review summarizes recent studies on the relationship between alcohol and nAChRs, including the role of nAChRs in molecular biological studies, genetic studies and pharmacological studies on alcohol, which indicate that nAChRs have been potently modulated by alcohol. Methods We performed a cross-referenced literature search on biological, genetic and pharmacological studies of alcohol and nAChRs. Results Molecular biological and genetic studies indicated that nAChR (genes may be important in mediating alcohol intake, but we still lack substantial evidence about how it works. Pharmacological studies proved the correlation between nAChRs and alcohol intake, and the association between nicotine and alcohol at the nAChRs. The positive findings of varenicline (a partial agonist at the _4_2 nAChR, smoking-cessation pharmaceutical treatment for alcoholism, provides a new insight for treating co-abuse of these two substances. >Conclusions Molecular biological, genetic and pharmacological studies of alcohol at the nAChR level, provide a new sight for preventing and treating the co-abuse of alcohol and nicotine. Given the important role of nAChRs in nicotine dependence, the interaction between alcohol and nAChRs would provide a new insight in finding effective pharmacological treatments, in decreasing or stopping alcohol consumption and cigarette smoking concurrently.

  17. Alcohol's actions on neuronal nicotinic acetylcholine receptors.

    Science.gov (United States)

    Davis, Tiffany J; de Fiebre, Christopher M

    2006-01-01

    Although it has been known for many years that alcoholism and tobacco addiction often co-occur, relatively little information is available on the biological factors that regulate the co-use and abuse of nicotine and alcohol. In the brain, nicotine acts at several different types of receptors collectively known as nicotinic acetylcholine receptors (nAChRs). Alcohol also acts on at least some of these receptors, enhancing the function of some nAChR subtypes and inhibiting the activity of others. Chronic alcohol and nicotine administration also lead to changes in the numbers of nAChRs. Natural variations (i.e., polymorphisms) in the genes encoding different nAChR subunits may be associated with individual differences in the sensitivity to some of alcohol's and nicotine's effects. Finally, at least one subtype of nAChR may help protect cells against alcohol-induced neurotoxicity.

  18. Palmitoylation of Nicotinic Acetylcholine Receptors

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    Alexander, J. K.; Govind, A. P.; Drisdel, R. C.; Blanton, M. P.; Vallejo, Y.; Lam, T. T.

    2012-01-01

    It is well established that nicotinic acetylcholine receptors (nAChRs) undergo a number of different post-translational modifications, such as disulfide bond formation, glycosylation, and phosphorylation. Recently, our laboratory has developed more sensitive assays of protein palmitoylation that have allowed us and others to detect the palmitoylation of relatively low abundant proteins such as ligand-gated ion channels. Here, we present evidence that palmitoylation is prevalent on many subunits of different nAChR subtypes, both muscle-type nAChRs and the neuronal “α4β2” and “α7” subtypes most abundant in brain. The loss of ligand binding sites that occurs when palmitoylation is blocked with the inhibitor bromopalmitate suggests that palmitoylation of α4β2 and α7 subtypes occurs during subunit assembly and regulates the formation of ligand binding sites. However, additional experiments are needed to test whether nAChR subunit palmitoylation is involved in other aspects of nAChR trafficking or whether palmitoylation regulates nAChR function. Further investigation would be aided by identifying the sites of palmitoylation on the subunits, and here we propose a mass spectrometry strategy for identification of these sites. PMID:19693711

  19. Structural Studies of Nicotinic Acetylcholine Receptors

    DEFF Research Database (Denmark)

    Shahsavar, Azadeh; Gajhede, Michael; Kastrup, Jette

    2016-01-01

    Nicotinic acetylcholine receptors (nAChRs) are members of the pentameric ligand-gated ion channel superfamily that play important roles in control of neurotransmitter release in the central and peripheral nervous system. These receptors are important therapeutic targets for development of drugs...

  20. 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...

  1. Nicotinic receptors in aging and dementia.

    Science.gov (United States)

    Picciotto, Marina R; Zoli, Michele

    2002-12-01

    Activation of neuronal nicotinic acetylcholine receptors (nAChRs) has been shown to maintain cognitive function following aging or the development of dementia. Nicotine and nicotinic agonists have been shown to improve cognitive function in aged or impaired subjects. Smoking has also been shown in some epidemiological studies to be protective against the development of neurodegenerative diseases. This is supported by animal studies that have shown nicotine to be neuroprotective both in vivo and in vitro. Treatment with nicotinic agonists may therefore be useful in both slowing the progression of neurodegenerative illnesses, and improving function in patients with the disease. While increased nicotinic function has been shown to be beneficial, loss of cholinergic markers is often seen in patients with dementia, suggesting that decreased cholinergic function could contribute to both the cognitive deficits, and perhaps the neuronal degeneration, associated with dementia. In this article we will review the literature on each of these areas. We will also present hypotheses that might address the mechanisms underlying the ability of nAChR function to protect against neurodegeneration or improve cognition, two potentially distinct actions of nicotine.

  2. Replicated Risk Nicotinic Cholinergic Receptor Genes for Nicotine Dependence

    Directory of Open Access Journals (Sweden)

    Lingjun Zuo

    2016-11-01

    Full Text Available 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.

  3. 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

    2016-01-01

    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. PMID:27827986

  4. 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.

  5. 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 and prote......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...

  6. 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 and prote......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...

  7. Central cholinergic regulation of respiration: nicotinic receptors

    Institute of Scientific and Technical Information of China (English)

    Xuesi M SHAO; Jack L FELDMAN

    2009-01-01

    Nicotinic acetylcholine receptors (nAChRs) are expressed in brainstem and spinal cord regions involved in the control of breathing. These receptors mediate central cholinergic regulation of respiration and effects of the exogenous ligand nicotine on respiratory pattern. Activation of a4* nAChRs in the preBotzinger Complex (preBotC), an essential site for normal respiratory rhythm generation in mammals, modulates excitatory glutamatergic neurotransmission and depolarizes preBotC inspiratory neurons, leading to increases in respiratory frequency. nAChRs are also present in motor nuclei innervating respiratory muscles. Activation of post- and/or extra-synaptic a4* nAChRs on hypoglossal (XII) motoneurons depolarizes these neurons, potentiating tonic and respiratory-related rhythmic activity. As perinatal nicotine exposure may contribute to the pathogenesis of sudden infant death syndrome (SIDS), we discuss the effects of perinatal nicotine exposure on development of the cholinergic and other neurotransmitter systems involved in control of breathing. Advances in understanding of the mechanisms underlying central cholinergic/nicotinic modulation of respiration provide a pharmacological basis for exploiting nAChRs as therapeutic targets for neurological disorders related to neural control of breathing such as sleep apnea and SIDS.

  8. Nicotinic Acetylcholine Receptors in Sensory Cortex

    Science.gov (United States)

    Metherate, Raju

    2004-01-01

    Acetylcholine release in sensory neocortex contributes to higher-order sensory function, in part by activating nicotinic acetylcholine receptors (nAChRs). Molecular studies have revealed a bewildering array of nAChR subtypes and cellular actions; however, there is some consensus emerging about the major nAChR subtypes and their functions in…

  9. Nicotinic Receptor Polymorphism in Lung Cancer

    Science.gov (United States)

    2013-10-01

    bronchial cells to the tobacco nitrosamine-induced carcinogenic transformation of human bronchial cells [1-2]. 15. SUBJECT TERMS nicotinic receptor...cells to the tobacco nitrosamine-induced carcinogenic transformation of human bronchial cells [1-2]. Body According to the Statement of Works

  10. Postsynaptic scaffolds for nicotinic receptors on neurons

    Institute of Scientific and Technical Information of China (English)

    Robert A NEFF III; David GOMEZ-VARELA; Catarina C FERNANDES; Darwin K BERG

    2009-01-01

    Complex postsynaptic scaffolds determine the structure and signaling capabilities of glutamatergic synapses. Recent studies indicate that some of the same scaffold components contribute to the formation and function of nicotinic synapses on neurons. PDZ-containing proteins comprising the PSD-95 family co-localize with nicotinic acetylcholine receptors (nAChRs) and mediate downstream signaling in the neurons. The PDZ-proteins also promote functional nicotinic innerva- tion of the neurons, as does the scaffold protein APC and transmembrane proteins such as neuroligin and the EphB2 recep- tor. In addition, specific chaperones have been shown to facilitate nAChR assembly and transport to the cell surface. This review summarizes recent results in these areas and raises questions for the future about the mechanism and synaptic role of nAChR trafficking.

  11. Nicotinic receptor abnormalities in Alzheimer's and Parkinson's diseases.

    OpenAIRE

    1987-01-01

    The status of cholinergic receptors in dementia is related to the question of potential cholinergic therapy. Whilst muscarinic receptor binding is generally reported to be normal or near normal, findings are reported which indicate substantial reductions of hippocampal nicotinic (high affinity nicotine) binding (occurring in conjunction with decreased choline acetyltransferase) in both Alzheimer's and Parkinson's but not Huntington's disease. A further indication that nicotinic receptor funct...

  12. Binding of quinolizidine alkaloids to nicotinic and muscarinic acetylcholine receptors.

    Science.gov (United States)

    Schmeller, T; Sauerwein, M; Sporer, F; Wink, M; Müller, W E

    1994-09-01

    Fourteen quinolizidine alkaloids, isolated from Lupinus albus, L. mutabilis, and Anagyris foetida, were analyzed for their affinity for nicotinic and/or muscarinic acetylcholine receptors. Of the compounds tested, the alpha-pyridones, N-methylcytisine and cytisine, showed the highest affinities at the nicotinic receptor, while several quinolizidine alkaloid types were especially active at the muscarinic receptor.

  13. Disconnection between activation and desensitization of autonomic nicotinic receptors by nicotine and cotinine.

    Science.gov (United States)

    Buccafusco, Jerry J; Shuster, Laura C; Terry, Alvin V

    2007-02-08

    Cotinine is the major metabolite of nicotine in humans, and the substance greatly outlasts the presence of nicotine in the body. Recently, cotinine has been shown to exert pharmacological properties of its own that include potential cognition enhancement, anti-psychotic activity, and cytoprotection. Since the metabolite is generally less potent than nicotine in vivo, we considered whether part of cotinine's efficacy could be related to a reduced ability to desensitize nicotinic receptors as compared with nicotine. Rats freely moving in their home cages were instrumented to allow ongoing measurement of mean arterial blood pressure (MAP). The ganglionic stimulant dimethylphenylpiperazinium (DMPP) maximally increased MAP by 25mmHg. Slow (20min) i.v. infusion of nicotine (0.25-1micromol) produced no change in resting MAP, but the pressor response to subsequent injection of DMPP was significantly attenuated in a dose-dependent manner by up to 51%. Pre-infusion of equivalent doses of cotinine produced the same maximal degree of inhibition of the response to DMPP. Discrete i.v. injections of nicotine also produced a dose dependent increase in MAP of up to 43mmHg after the highest tolerated dose. In contrast, injection of cotinine produced no significant change in MAP up to 13 times the highest dose of nicotine. These results illustrate the disconnection between nicotinic receptor activation and receptor desensitization, and they suggest that cotinine's pharmacological actions are either mediated through partial desensitization, or through non-ganglionic subtypes of nicotinic receptors.

  14. Brain β2*-nicotinic acetylcholine receptor occupancy after use of a nicotine inhaler

    OpenAIRE

    Esterlis, Irina; Effie M Mitsis; Batis, Jeffery C.; Bois, Frederic; Picciotto, Marina R.; Stiklus, Stephanie M.; Kloczynski, Tracy; Perry, Edward; Seibyl, John P.; McKee, Sherry; Staley, Julie K.; Cosgrove, Kelly P.

    2010-01-01

    The Nicotrol® (Pfizer, USA) nicotine inhaler reduces craving by mimicking the behavioural component of cigarettes and delivering controlled doses of nicotine, which binds to the beta-2 subunit-containing nicotinic acetylcholine receptors (β2*-nAChRs). Previous studies examined β2*-nAChR occupancy after administration of regular and low-nicotine cigarettes. Here, we measured occupancy of β2*-nAChRs after administration of nicotine via inhaler, and the relationship between occupancy and changes...

  15. Rigid analogs of DMPP as probes for the nicotinic receptors.

    Science.gov (United States)

    Guandalini, Luca; Martini, Elisabetta; Martelli, Cecilia; Romanelli, M Novella; Varani, Katia

    2005-02-01

    Chemical manipulation of the nicotinic agonist DMPP, endowed with modest activity on the central receptors, definitely improved its affinity and pharmacokinetic properties. Although their pharmacophore is somehow different from that of classical nicotinic ligands, some DMPP derivatives show low nanomolar affinity for the central nicotinic receptors. Introduction of rigidity in the structure of DMPP and in that of its analogue 1-(3-pyridyl)piperazine, resulted in molecules with lower or null affinity for the central nicotinic receptors. This suggests that the frozen structures chosen either do not represent the bioactive conformation, or their volume is not compatible with the space available within the interaction site.

  16. 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.

  17. Nicotine and Nicotinic Receptor Drugs: Potential for Parkinson's Disease and Drug-Induced Movement Disorders.

    Science.gov (United States)

    Quik, Maryka; Bordia, Tanuja; Zhang, Danhui; Perez, Xiomara A

    2015-01-01

    Parkinson's disease is a progressive neurodegenerative disorder associated with tremor, rigidity, and bradykinesia, as well as nonmotor symptoms including autonomic impairments, olfactory dysfunction, sleep disturbances, depression, and dementia. Although the major neurological deficit is a loss of nigrostriatal dopaminergic neurons, multiple neurotransmitters systems are compromised in Parkinson's disease. Consistent with this observation, dopamine replacement therapy dramatically improves Parkinson's disease motor symptoms. Additionally, drugs targeting the serotonergic, glutamatergic, adenosine, and other neurotransmitter systems may be beneficial. Recent evidence also indicates that nicotinic cholinergic drugs may be useful for the management of Parkinson's disease. This possibility initially arose from the results of epidemiological studies, which showed that smoking was associated with a decreased incidence of Parkinson's disease, an effect mediated in part by the nicotine in smoke. Further evidence for this idea stemmed from preclinical studies which showed that nicotine administration reduced nigrostriatal damage in parkinsonian rodents and monkeys. In addition to a potential neuroprotective role, emerging work indicates that nicotinic receptor drugs improve the abnormal involuntary movements or dyskinesias that arise as a side effect of l-dopa treatment, the gold standard therapy for Parkinson's disease. Both nicotine and nicotinic receptor drugs reduced l-dopa-induced dyskinesias by over 50% in parkinsonian rodent and monkey models. Notably, nicotine also attenuated the abnormal involuntary movements or tardive dyskinesias that arise with antipsychotic treatment. These observations, coupled with reports that nicotinic receptor drugs have procognitive and antidepressant effects, suggest that central nervous system (CNS) nicotinic receptors may represent useful targets for the treatment of movement disorders.

  18. Conotoxins Targeting Nicotinic Acetylcholine Receptors: An Overview

    OpenAIRE

    2014-01-01

    Marine snails of the genus Conus are a large family of predatory gastropods with an unparalleled molecular diversity of pharmacologically active compounds in their venom. Cone snail venom comprises of a rich and diverse cocktail of peptide toxins which act on a wide variety of ion channels such as voltage-gated sodium- (NaV), potassium- (KV), and calcium- (CaV) channels as well as nicotinic acetylcholine receptors (nAChRs) which are classified as ligand-gated ion channels. The mode of action ...

  19. Cellular trafficking of nicotinic acetylcholine receptors

    Institute of Scientific and Technical Information of China (English)

    Paul A ST JOHN

    2009-01-01

    Nicotinic acetylcholine receptors (nAChRs) play critical roles throughout the body. Precise regulation of the cellular location and availability of nAChRs on neurons and target cells is critical to their proper function. Dynamic, post-translational regulation of nAChRs, particularly control of their movements among the different compartments of cells, is an important aspect of that regulation. A combination of new information and new techniques has the study of nAChR trafficking poised for new breakthroughs.

  20. Nicotine enhancement and reinforcer devaluation: Interaction with opioid receptors.

    Science.gov (United States)

    Kirshenbaum, Ari P; Suhaka, Jesse A; Phillips, Jessie L; Voltolini de Souza Pinto, Maiary

    In rats, nicotine enhances responding maintained by non-pharmacological reinforcers, and discontinuation of nicotine devalues those same reinforcers. The goal of this study was to assess the interaction of nicotine and opioid receptors and to evaluate the degree to which nicotine enhancement and nicotine-induced devaluation are related to opioid activation. Nicotine (0.4mg/kg), or nicotine plus naloxone (0.3 or 3.0mg/kg), was delivered to rats prior to progressive ratio (PR) schedule sessions in which sucrose was used as a reinforcer. PR-schedule responding was assessed during ten daily sessions of drug delivery, and for three post-dosing days/sessions. Control groups for this investigation included a saline-only condition, and naloxone-only (0.3 or 3.0mg/kg) conditions. When administered in conjunction with nicotine, both naloxone doses attenuated nicotine enhancement of the sucrose reinforcer, and the combination of the larger dose of naloxone (3.0mg/kg) with nicotine produced significant impairments in sucrose reinforced responding. When administered alone, neither dose of naloxone (0.3 & 3.0mg/kg) significantly altered responding in comparison to saline. Furthermore, when dosing was discontinued after ten once-daily doses, all nicotine groups (nicotine-only and nicotine+naloxone combination) demonstrated significant decreases in sucrose reinforcement compared to the saline group. Although opioid antagonism attenuated reinforcement enhancement by nicotine, it did not prevent reinforcer devaluation upon discontinuation of nicotine dosing, and the higher dose of naloxone (3.0mg/kg) produced decrements upon discontinuation on its own in the absence of nicotine.

  1. Tying up Nicotine: New Selective Competitive Antagonist of the Neuronal Nicotinic Acetylcholine Receptors

    DEFF Research Database (Denmark)

    Petersen, Ida Nymann; Crestey, François; Jensen, Anders A

    2015-01-01

    Conformational restriction of the pyrrolidine nitrogen in nicotine by the introduction of an ethylene bridge provided a potent and selective antagonist of the α4β2-subtype of the nicotinic acetylcholine receptors. Resolution by chiral SFC, pharmacological characterization of the two enantiomers...

  2. 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

  3. The therapeutic promise of positive allosteric modulation of nicotinic receptors.

    Science.gov (United States)

    Uteshev, Victor V

    2014-03-15

    In the central nervous system, deficits in cholinergic neurotransmission correlate with decreased attention and cognitive impairment, while stimulation of neuronal nicotinic acetylcholine receptors improves attention, cognitive performance and neuronal resistance to injury as well as produces robust analgesic and anti-inflammatory effects. The rational basis for the therapeutic use of orthosteric agonists and positive allosteric modulators (PAMs) of nicotinic receptors arises from the finding that functional nicotinic receptors are ubiquitously expressed in neuronal and non-neuronal tissues including brain regions highly vulnerable to traumatic and ischemic types of injury (e.g., cortex and hippocampus). Moreover, functional nicotinic receptors do not vanish in age-, disease- and trauma-related neuropathologies, but their expression and/or activation levels decline in a subunit- and brain region-specific manner. Therefore, augmenting the endogenous cholinergic tone by nicotinic agents is possible and may offset neurological impairments associated with cholinergic hypofunction. Importantly, because neuronal damage elevates extracellular levels of choline (a selective agonist of α7 nicotinic acetylcholine receptors) near the site of injury, α7-PAM-based treatments may augment pathology-activated α7-dependent auto-therapies where and when they are most needed (i.e., in the penumbra, post-injury). Thus, nicotinic-PAM-based treatments are expected to augment the endogenous cholinergic tone in a spatially and temporally restricted manner creating the potential for differential efficacy and improved safety as compared to exogenous orthosteric nicotinic agonists that activate nicotinic receptors indiscriminately. In this review, I will summarize the existing trends in therapeutic applications of nicotinic PAMs.

  4. 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.

  5. Conotoxins Targeting Nicotinic Acetylcholine Receptors: An Overview

    Directory of Open Access Journals (Sweden)

    Eline K. M. Lebbe

    2014-05-01

    Full Text Available Marine snails of the genus Conus are a large family of predatory gastropods with an unparalleled molecular diversity of pharmacologically active compounds in their venom. Cone snail venom comprises of a rich and diverse cocktail of peptide toxins which act on a wide variety of ion channels such as voltage-gated sodium- (NaV, potassium- (KV, and calcium- (CaV channels as well as nicotinic acetylcholine receptors (nAChRs which are classified as ligand-gated ion channels. The mode of action of several conotoxins has been the subject of investigation, while for many others this remains unknown. This review aims to give an overview of the knowledge we have today on the molecular pharmacology of conotoxins specifically interacting with nAChRs along with the structure–function relationship data.

  6. Modulation of nicotinic acetylcholine receptors by strychnine

    Science.gov (United States)

    García-Colunga, Jesús; Miledi, Ricardo

    1999-01-01

    Strychnine, a potent and selective antagonist at glycine receptors, was found to inhibit muscle (α1β1γδ, α1β1γ, and α1β1δ) and neuronal (α2β2 and α2β4) nicotinic acetylcholine receptors (AcChoRs) expressed in Xenopus oocytes. Strychnine alone (up to 500 μM) did not elicit membrane currents in oocytes expressing AcChoRs, but, when applied before, concomitantly, or during superfusion of acetylcholine (AcCho), it rapidly and reversibly inhibited the current elicited by AcCho (AcCho-current). Although in the three cases the AcCho-current was reduced to the same level, its recovery was slower when the oocytes were preincubated with strychnine. The amount of AcCho-current inhibition depended on the receptor subtype, and the order of blocking potency by strychnine was α1β1γδ > α2β4 > α2β2. With the three forms of drug application, the Hill coefficient was close to one, suggesting a single site for the receptor interaction with strychnine, and this interaction appears to be noncompetitive. The inhibitory effects on muscle AcChoRs were voltage-independent, and the apparent dissociation constant for AcCho was not appreciably changed by strychnine. In contrast, the inhibitory effects on neuronal AcChoRs were voltage-dependent, with an electrical distance of ≈0.35. We conclude that strychnine regulates reversibly and noncompetitively the embryonic type of muscle AcChoR and some forms of neuronal AcChoRs. In the former case, strychnine presumably inhibits allosterically the receptor by binding at an external domain whereas, in the latter case, it blocks the open receptor-channel complex. PMID:10097172

  7. Activities of nicotinic acetylcholine receptors modulate neurotransmission and synaptic architecture

    Institute of Scientific and Technical Information of China (English)

    Akira Oda; Hidekazu Tanaka

    2014-01-01

    The cholinergic system is involved in a broad spectrum of brain function, and its failure has been implicated in Alzheimer’s disease. Acetylcholine transduces signals through muscarinic and nicotinic acetylcholine receptors, both of which inlfuence synaptic plasticity and cognition. However, the mechanisms that relate the rapid gating of nicotinic acetylcholine receptors to per-sistent changes in brain function have remained elusive. Recent evidence indicates that nicotinic acetylcholine receptors activities affect synaptic morphology and density, which result in per-sistent rearrangements of neural connectivity. Further investigations of the relationships between nicotinic acetylcholine receptors and rearrangements of neural circuitry in the central nervous system may help understand the pathogenesis of Alzheimer’s disease.

  8. Schizophrenia and the alpha7 nicotinic acetylcholine receptor.

    Science.gov (United States)

    Martin, Laura F; Freedman, Robert

    2007-01-01

    In addition to the devastating symptoms of psychosis, many people with schizophrenia also suffer from cognitive impairment. These cognitive symptoms lead to marked dysfunction and can impact employability, treatment adherence, and social skills. Deficits in P50 auditory gating are associated with attentional impairment and may contribute to cognitive symptoms and perceptual disturbances. This nicotinic cholinergic-mediated inhibitory process represents a potential new target for therapeutic intervention in schizophrenia. This chapter will review evidence implicating the nicotinic cholinergic, and specifically, the alpha7 nicotinic receptor system in the pathology of schizophrenia. Impaired auditory sensory gating has been linked to the alpha7 nicotinic receptor gene on the chromosome 15q14 locus. A majority of persons with schizophrenia are heavy smokers. Although nicotine can acutely reverse diminished auditory sensory gating in people with schizophrenia, this effect is lost on a chronic basis due to receptor desensitization. The alpha7 nicotinic agonist 3-(2,4 dimethoxy)benzylidene-anabaseine (DMXBA) can also enhance auditory sensory gating in animal models. DMXBA is well tolerated in humans and a new study in persons with schizophrenia has found that DMXBA enhances both P50 auditory gating and cognition. alpha7 Nicotinic acetylcholine receptor agonists appear to be viable candidates for the treatment of cognitive disturbances in schizophrenia.

  9. Nicotine enhances alcohol intake and dopaminergic responses through β2* and β4* nicotinic acetylcholine receptors

    Science.gov (United States)

    Tolu, Stefania; Marti, Fabio; Morel, Carole; Perrier, Carole; Torquet, Nicolas; Pons, Stephanie; de Beaurepaire, Renaud; Faure, Philippe

    2017-01-01

    Alcohol and nicotine are the most widely co-abused drugs. Both modify the activity of dopaminergic (DA) neurons of the Ventral Tegmental Area (VTA) and lead to an increase in DA release in the Nucleus Accumbens, thereby affecting the reward system. Evidences support the hypothesis that distinct nicotinic acetylcholine receptors (nAChRs), the molecular target of acetylcholine (ACh) and exogenous nicotine, are also in addition implicated in the response to alcohol. The precise molecular and neuronal substrates of this interaction are however not well understood. Here we used in vivo electrophysiology in the VTA to characterise acute and chronic interactions between nicotine and alcohol. Simultaneous injections of the two drugs enhanced their responses on VTA DA neuron firing and chronic exposure to nicotine increased alcohol-induced DA responses and alcohol intake. Then, we assessed the role of β4 * nAChRs, but not β2 * nAChRs, in mediating acute responses to alcohol using nAChR subtypes knockout mice (β2−/− and β4−/− mice). Finally, we showed that nicotine-induced modifications of alcohol responses were absent in β2−/− and β4−/− mice, suggesting that nicotine triggers β2* and β4 * nAChR-dependent neuroadaptations that subsequently modify the responses to alcohol and thus indicating these receptors as key mediators in the complex interactions between these two drugs. PMID:28332590

  10. Habenular expression of rare missense variants of the β4 nicotinic receptor subunit alters nicotine consumption

    Science.gov (United States)

    Ślimak, Marta A.; Ables, Jessica L.; Frahm, Silke; Antolin-Fontes, Beatriz; Santos-Torres, Julio; Moretti, Milena; Gotti, Cecilia; Ibañez-Tallon, Inés

    2013-01-01

    The CHRNA5-CHRNA3-CHRNB4 gene cluster, encoding the α5, α3, and β4 nicotinic acetylcholine receptor (nAChR) subunits, has been linked to nicotine dependence. The habenulo-interpeduncular (Hb-IPN) tract is particularly enriched in α3β4 nAChRs. We recently showed that modulation of these receptors in the medial habenula (MHb) in mice altered nicotine consumption. Given that β4 is rate-limiting for receptor activity and that single nucleotide polymorphisms (SNPs) in CHRNB4 have been linked to altered risk of nicotine dependence in humans, we were interested in determining the contribution of allelic variants of β4 to nicotine receptor activity in the MHb. We screened for missense SNPs that had allele frequencies >0.0005 and introduced the corresponding substitutions in Chrnb4. Fourteen variants were analyzed by co-expression with α3. We found that β4A90I and β4T374I variants, previously shown to associate with reduced risk of smoking, and an additional variant β4D447Y, significantly increased nicotine-evoked current amplitudes, while β4R348C, the mutation most frequently encountered in sporadic amyotrophic lateral sclerosis (sALS), showed reduced nicotine currents. We employed lentiviruses to express β4 or β4 variants in the MHb. Immunoprecipitation studies confirmed that β4 lentiviral-mediated expression leads to specific upregulation of α3β4 but not β2 nAChRs in the Mhb. Mice injected with the β4-containing virus showed pronounced aversion to nicotine as previously observed in transgenic Tabac mice overexpressing Chrnb4 at endogenous sites including the MHb. Habenular expression of the β4 gain-of-function allele T374I also resulted in strong aversion, while transduction with the β4 loss-of function allele R348C failed to induce nicotine aversion. Altogether, these data confirm the critical role of habenular β4 in nicotine consumption, and identify specific SNPs in CHRNB4 that modify nicotine-elicited currents and alter nicotine consumption in

  11. 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

  12. Nicotinic acetylcholine receptors: from basic science to therapeutics.

    Science.gov (United States)

    Hurst, Raymond; Rollema, Hans; Bertrand, Daniel

    2013-01-01

    Substantial progress in the identification of genes encoding for a large number of proteins responsible for various aspects of neurotransmitter release, postsynaptic detection and downstream signaling, has advanced our understanding of the mechanisms by which neurons communicate and interact. Nicotinic acetylcholine receptors represent a large and well-characterized family of ligand-gated ion channels that is expressed broadly throughout the central and peripheral nervous system, and in non-neuronal cells. With 16 mammalian genes identified that encode for nicotinic receptors and the ability of the subunits to form heteromeric or homomeric receptors, the repertoire of conceivable receptor subtype combinations is enormous and offers unique possibilities for the design and development of new therapeutics that target nicotinic acetylcholine receptors. The aim of this review is to provide the reader with recent insights in nicotinic acetylcholine receptors from genes, structure and function to diseases, and with the latest findings on the pharmacology of these receptors. Although so far only a few nicotinic drugs have been marketed or are in late stage development, much progress has been made in the design of novel chemical entities that are being explored for the treatment of various diseases, including addiction, depression, ADHD, cognitive deficits in schizophrenia and Alzheimer's disease, pain and inflammation. A pharmacological analysis of these compounds, including those that were discontinued, can improve our understanding of the pharmacodynamic and pharmacokinetic requirements for nicotinic 'drug-like' molecules and will reveal if hypotheses on therapies based on targeting specific nicotinic receptor subtypes have been adequately tested in the clinic.

  13. 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...... brain. Additionally, soluble recombinant Lypd6 protein attenuates nicotine-induced hippocampal inward currents in rat brain slices and decreases nicotine-induced extracellular signal-regulated kinase phosphorylation in PC12 cells, suggesting that binding of Lypd6 is sufficient to inhibit n......AChR-mediated intracellular signaling. We further show that perinatal nicotine exposure in rats (4 mg/kg/day through minipumps to dams from embryonic day 7 to post-natal day 21) significantly increases Lypd6 protein levels in the hippocampus in adulthood, which did not occur after exposure to nicotine in adulthood only. Our...

  14. Nicotine-morphine interactions at α4β2, α7 and α3(⁎) nicotinic acetylcholine receptors.

    Science.gov (United States)

    Talka, Reeta; Salminen, Outi; Whiteaker, Paul; Lukas, Ronald J; Tuominen, Raimo K

    2013-02-15

    Nicotine and opioids share several behavioral and rewarding properties. Although both opioids and nicotine have their own specific mechanism of action, there is empirical and experimental evidence of interactions between these drugs. We studied receptor-level interactions of nicotine and morphine at α4β2, α7 and α3(⁎) nicotinic acetylcholine receptors. [(3)H]epibatidine displacement was used to determine if morphine binds competitively to nicotinic acetylcholine receptors. Functional interactions of morphine and nicotine were studied with calcium fluorometry and (86)Rb(+) efflux assays. Morphine displaced [(3)H]epibatidine from nicotinic agonist binding sites in all cell lines studied. The Ki values for morphine were 13.2μM in SH-EP1-hα4β2 cells, 0.16μM and 126μM in SH-SY5Y cells and 43.7μM in SH-EP1-hα7 cells. In SH-EP1-hα4β2 cells expressing α4β2 nicotinic acetylcholine receptors, morphine acted as a partial agonist of (86)Rb(+) efflux comparable to cytisine (with EC50 values of 53.3μM for morphine and 5.38μM for cytisine). The effect of morphine was attenuated concentration-dependently by the nicotinic antagonist mecamylamine. In the SH-SY5Y cell line expressing several subtypes of nicotinic acetylcholine receptors morphine had an inhibitory effect on nicotine induced (86)Rb(+) ion efflux mediated by α3(⁎) nicotinic acetylcholine receptors. These results suggest that morphine acts as a partial agonist at α4β2 nicotinic acetylcholine receptors and as a weak antagonist at α3(⁎) nicotinic acetylcholine receptors.

  15. Nicotine-induced alterations in the expression of nicotinic receptors in primary cultures from human prenatal brain.

    Science.gov (United States)

    Hellström-Lindahl, E; Seiger A; Kjaeldgaard, A; Nordberg, A

    2001-01-01

    The nicotinic receptor proteins and gene transcripts for the different nicotinic receptor subunits exist in human prenatal brain already at 4-5 weeks of gestation. The early presence of nicotinic receptors suggests an important role for these receptors in modulating dendritic outgrowth, establishment of neuronal connections and synaptogenesis during development. When measurements of nicotinic receptors using [(3)H]epibatidine (labelling both the alpha3 and alpha4 subtype) and [(3)H]cytisine (labelling the alpha4 subtype) were performed in intact cells from the cortex, subcortical forebrain and mesencephalon (7.5-11 weeks of gestation), the highest specific binding for both ligands was detected in cells from mesencephalon, followed by subcortical forebrain and cortex. The effects of nicotine exposure were studied in primary cultures of prenatal brain (7.5-11 weeks of gestation). Treatment with nicotine (1-100 microM) for 3 days significantly increased the specific binding of [(3)H]epibatidine and [(3)H]cytisine in cortical cells but not in cells from subcortical forebrain and mesencephalon brain regions, indicating region-specific differences in the sensitivity to nicotine exposure. Relative quantification of mRNA showed that the expression of the nicotinic receptor subunits alpha3 and alpha7, but not alpha4, was increased in cortical cells after nicotine treatment. These findings support the assumption of a potential risk of disturbance in the functional role of nicotinic receptors during brain development as a consequence of maternal smoking during pregnancy.

  16. Binding of tropane alkaloids to nicotinic and muscarinic acetylcholine receptors.

    Science.gov (United States)

    Schmeller, T; Sporer, F; Sauerwein, M; Wink, M

    1995-07-01

    Fourteen tropane and related alkaloids were analyzed for their affinity for nicotinic and/or muscarinic acetylcholine receptors. The biogenetic intermediates littorine, 6 beta-hydroxyhyoscyamine, 7 beta-hydroxyhyoscyamine exhibit similar affinities at the muscarinic receptor as scopolamine and atropine. The quarternary derivatives N-methylatropine and N-methylscopolamine show the highest binding with IC50 values of less than 100 pM and 300 pM, respectively. The tropane alkaloids (including cocaine) also bind to the nicotinic acetylcholine receptor, albeit with much lower affinities.

  17. A physical model of nicotinic ACh receptor kinetics

    OpenAIRE

    Nurowska, Ewa; Bratiichuk, Mykola; Dworakowska, Beata; Nowak, Roman J.

    2008-01-01

    We present a new approach to nicotinic receptor kinetics and a new model explaining random variabilities in the duration of open events. The model gives new interpretation on brief and long receptor openings and predicts (for two identical binding sites) the presence of three components in the open time distribution: two brief and a long. We also present the physical model of the receptor block. This picture naturally and universally explains receptor desensitization, the phenomenon of centra...

  18. 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 hydr

  19. Melatonin modulation of presynaptic nicotinic acetylcholine receptors located on short noradrenergic neurons of the rat vas deferens: a pharmacological characterization

    Directory of Open Access Journals (Sweden)

    Zago W.M.

    1999-01-01

    Full Text Available Melatonin, the pineal hormone produced during the dark phase of the light-dark cycle, modulates neuronal acetylcholine receptors located presynaptically on nerve terminals of the rat vas deferens. Recently we showed the presence of high affinity nicotine-binding sites during the light phase, and low and high affinity binding sites during the dark phase. The appearance of the low affinity binding sites was due to the nocturnal melatonin surge and could be mimicked by exposure to melatonin in vitro. The aim of the present research was to identify the receptor subtypes responsible for the functional response during the light and the dark phase. The rank order of potency of agonists was dimethylphenylpiperazinium (DMPP = cytisine > nicotine > carbachol and DMPP = nicotine = cytisine > carbachol, during the light and dark phase, respectively, due to an increase in apparent affinity for nicotine. Mecamylamine similarly blocked the DMPP response during the light and the dark phase, while the response to nicotine was more efficiently blocked during the light phase. In contrast, methyllycaconitine inhibited the nicotine-induced response only at 21:00 h. Since a7 nicotinic acetylcholine receptors (nAChRs have low affinity for nicotine in binding assays, we suggest that a mixed population composed of a3ß4 - plus a7-bearing nAChR subtypes is present at night. This plasticity in receptor subtypes is probably driven by melatonin since nicotine-induced contraction in organs from animals sacrificed at 15:00 h and incubated with melatonin (100 pg/ml, 4 h is not totally blocked by mecamylamine. Thus melatonin, by acting directly on the short adrenergic neurons that innervate the rat vas deferens, induces the appearance of the low affinity binding site, probably an a7 nAChR subtype.

  20. Modal gating of muscle nicotinic acetylcholine receptors

    Science.gov (United States)

    Vij, Ridhima

    Many ion channels exhibit multiple patterns of kinetic activity in single-channel currents. This behavior is rare in WT mouse muscle nicotinic acetylcholine receptors (AChRs), where A2C↔A2O gating events are well-described by single exponentials. Also, single-channel open probability (PO) is essentially homogeneous at a given agonist concentration in the WT receptors. Here I report that perturbations of almost all the residues in loop C (alpha188-alpha199, at the agonist binding site) generate heterogeneity in PO ('modes'). Such unsettled activity was apparent with an alanine substitution at all positions in loop C (except alphaY190 and alphaY198) and with different side chain substitutions at alphaP197 for both adult- and fetal-type AChRs. I used single channel electrophysiology along with site-directed mutagenesis to study modal gating in AChRs consequent to mutations/deletions in loop C. The multiple patterns of kinetic activity arose from the difference in agonist affinity rather than in intrinsic AChR gating. Out of the four different agonists used to study the modal behavior, acetylcholine (ACh) showed a higher degree of kinetic heterogeneity compared to others. The time constant for switching between modes was long (~mins), suggesting that they arise from alternative, stable protein conformations. By studying AChRs having only 1 functional binding site, I attempted to find the source of the affinity difference, which was traced mainly to the alphadelta agonist site. Affinity at the neurotransmitter binding site is mainly determined by a core of five aromatic residues (alphaY93, alphaW149, alphaY190, alphaY198 and deltaW57). Phenylalanine substitutions at all aromatic residues except alphaY93 resulted in elimination of modes. Modes were also eliminated by alanine mutation at deltaW57 on the complementary side but not at other aromatics. Also, by substituting four gamma subunit residues into the delta subunit on the complementary beta sheet, I found that

  1. Neuronal nicotinic acetylcholine receptors: Common molecular substrates of nicotine and alcohol dependence

    Directory of Open Access Journals (Sweden)

    Linzy M. Hendrickson

    2013-04-01

    Full Text Available Alcohol and nicotine are often co-abused. As many as 80-95% of alcoholics are also smokers, suggesting that ethanol and nicotine, the primary addictive component of tobacco smoke, may functionally interact in the central nervous system and/or share a common mechanism of action. While nicotine initiates dependence by binding to and activating neuronal nicotinic acetylcholine receptors (nAChRs, ligand-gated cation channels normally activated by endogenous acetylcholine (ACh, ethanol is much less specific with the ability to modulate multiple gene products including those encoding voltage-gated ion channels, and excitatory/inhibitory neurotransmitter receptors. However, emerging data indicate that ethanol interacts with nAChRs, both directly and indirectly, in the mesocorticolimbic dopaminergic (DAergic reward circuitry to affect brain reward systems. Like nicotine, ethanol activates DAergic neurons of the ventral tegmental area (VTA which project to the nucleus accumbens (NAc. Blockade of VTA nAChRs reduces ethanol-mediated activation of DAergic neurons, NAc DA release, consumption, and operant responding for ethanol in rodents. Thus, ethanol may increase ACh release into the VTA driving activation of DAergic neurons through nAChRs. In addition, ethanol potentiates distinct nAChR subtype responses to ACh and nicotine in vitro and in DAergic neurons. The smoking cessation therapeutic and nAChR partial agonist, varenicline, reduces alcohol consumption in heavy drinking smokers and rodent models of alcohol consumption. Finally, single nucleotide polymorphisms in nAChR subunit genes are associated with alcohol dependence phenotypes and smoking behaviors in human populations. Together, results from preclinical, clinical, and genetic studies indicate that nAChRs may have an inherent role in the abusive properties of ethanol, as well as in nicotine and alcohol co-dependence.

  2. 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.

  3. 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

    2012-02-08

    Nicotine causes changes in brain nicotinic acetylcholine receptors (nAChRs) during smoking that initiate addiction. Nicotine-induced upregulation is the long-lasting increase in nAChR radioligand 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 rat 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 demonstrates 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 radioligand 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.

  4. Pathogenesis of Abdominal Aortic Aneurysms: Role of Nicotine and Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Zong-Zhuang Li

    2012-01-01

    Full Text Available Inflammation, proteolysis, smooth muscle cell apoptosis, and angiogenesis have been implicated in the pathogenesis of abdominal aortic aneurysms (AAAs, although the well-defined initiating mechanism is not fully understood. Matrix metalloproteinases (MMPs such as MMP-2 and -9 and other proteinases degrading elastin and extracellular matrix are the critical pathogenesis of AAAs. Among the risk factors of AAAs, cigarette smoking is an irrefutable one. Cigarette smoke is practically involved in various aspects of the AAA pathogenesis. Nicotine, a major alkaloid in tobacco leaves and a primary component in cigarette smoke, can stimulate the MMPs expression by vascular SMCs, endothelial cells, and inflammatory cells in vascular wall and induce angiogenesis in the aneurysmal tissues. However, for the inflammatory and apoptotic processes in the pathogenesis of AAAs, nicotine seems to be moving in just the opposite direction. Additionally, the effects of nicotine are probably dose dependent or associated with the exposure duration and may be partly exerted by its receptors—nicotinic acetylcholine receptors (nAChRs. In this paper, we will mainly discuss the pathogenesis of AAAs involving inflammation, proteolysis, smooth muscle cell apoptosis and angiogenesis, and the roles of nicotine and nAChRs.

  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...

  6. Central nicotinic receptors: structure, function, ligands, and therapeutic potential.

    Science.gov (United States)

    Romanelli, M Novella; Gratteri, Paola; Guandalini, Luca; Martini, Elisabetta; Bonaccini, Claudia; Gualtieri, Fulvio

    2007-06-01

    The growing interest in nicotinic receptors, because of their wide expression in neuronal and non-neuronal tissues and their involvement in several important CNS pathologies, has stimulated the synthesis of a high number of ligands able to modulate their function. These membrane proteins appear to be highly heterogeneous, and still only incomplete information is available on their structure, subunit composition, and stoichiometry. This is due to the lack of selective ligands to study the role of nAChR under physiological or pathological conditions; so far, only compounds showing selectivity between alpha4beta2 and alpha7 receptors have been obtained. The nicotinic receptor ligands have been designed starting from lead compounds from natural sources such as nicotine, cytisine, or epibatidine, and, more recently, through the high-throughput screening of chemical libraries. This review focuses on the structure of the new agonists, antagonists, and allosteric ligands of nicotinic receptors, it highlights the current knowledge on the binding site models as a molecular modeling approach to design new compounds, and it discusses the nAChR modulators which have entered clinical trials.

  7. 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...

  8. 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

  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. 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......AChRs in human brain extracts, identifying Lypd6 as a novel regulator of nAChR function. Using protein cross-linking and affinity purification from human temporal cortical extracts, we demonstrate that Lypd6 is a synaptically enriched membrane-bound protein that binds to multiple nAChR subtypes in the human...... brain. Additionally, soluble recombinant Lypd6 protein attenuates nicotine-induced hippocampal inward currents in rat brain slices and decreases nicotine-induced extracellular signal-regulated kinase phosphorylation in PC12 cells, suggesting that binding of Lypd6 is sufficient to inhibit n...

  11. 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...

  12. Structural and functional diversity of native brain neuronal nicotinic receptors.

    Science.gov (United States)

    Gotti, Cecilia; Clementi, Francesco; Fornari, Alice; Gaimarri, Annalisa; Guiducci, Stefania; Manfredi, Irene; Moretti, Milena; Pedrazzi, Patrizia; Pucci, Luca; Zoli, Michele

    2009-10-01

    Neuronal nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels present in the central and peripheral nervous systems, that are permeable to mono- and divalent cations. They share a common basic structure but their pharmacological and functional properties arise from the wide range of different subunit combinations making up distinctive subtypes. nAChRs are involved in many physiological functions in the central and peripheral nervous systems, and are the targets of the widely used drug of abuse nicotine. In addition to tobacco dependence, changes in their number and/or function are associated with neuropsychiatric disorders, ranging from epilepsy to dementia. Although some of the neural circuits involved in the acute and chronic effects of nicotine have been identified, much less is known about which native nAChR subtypes are involved in specific physiological functions and pathophysiological conditions. We briefly review some recent findings concerning the structure and function of native nAChRs, focusing on the subtypes identified in the mesostriatal and habenulo-interpeduncular pathways, two systems involved in nicotine reinforcement and withdrawal. We also discuss recent findings concerning the effect of chronic nicotine on the expression of native subtypes.

  13. r-bPiDI, an α6β2* Nicotinic Receptor Antagonist, Decreases Nicotine-Evoked Dopamine Release and Nicotine Reinforcement

    Science.gov (United States)

    Beckmann, Joshua S.; Meyer, Andrew C.; Pivavarchyk, M.; Horton, David B.; Zheng, Guangrong; Smith, Andrew M.; Wooters, Thomas E.; McIntosh, J. Michael; Crooks, Peter A.; Bardo, Michael T.

    2015-01-01

    α6β2* nicotinic acetylcholine receptors (nACh Rs) expressed by dopaminergic neurons mediate nicotine-evoked dopamine (DA) release and nicotine reinforcement. α6β2* antagonists inhibit these effects of nicotine, such that α6β2* receptors serve as therapeutic targets for nicotine addiction. The present research assessed the neuropharmacology of 1,10-bis(3-methyl-5,6-dihydropyridin-1(2H)-yl)decane (r-bPiDI), a novel small-molecule, tertiary amino analog of its parent compound, N,N-decane-1,10-diyl-bis-3-picolinium diiodide (bPiDI). bPiDI was previously shown to inhibit both nicotine-evoked DA release and the reinforcing effects of nicotine. In the current study, r-bPiDI inhibition of [3H]nicotine and [3H]methyllyca-conitine binding sites was evaluated to assess interaction with the recognition binding sites on α4β2* and α7* nAChRs, respectively. Further, r-bPiDI inhibition of nicotine-evoked DA release in vitro in the absence and presence of α-conotoxin MII and following chronic in vivo nicotine administration were determined. The ability of r-bPiDI to decrease nicotine self-administration and food-maintained responding was also assessed. Results show that r-bPiDI did not inhibit [3H]nicotine or [3H]methylly-caconitine binding, but potently (IC50 = 37.5 nM) inhibited nicotine-evoked DA release from superfused striatal slices obtained from either drug naïve rats or from those repeatedly treated with nicotine. r-bPiDI inhibition of nicotine-evoked DA release was not different in the absence or presence of α-conotoxin MII, indicating that r-bPiDI acts as a potent, selective α6β2* nAChR antagonist. Acute systemic administration of r-bPiDI specifically decreased nicotine self-administration by 75 %, and did not alter food-maintained responding, demonstrating greater specificity relative to bPiDI and bPiDDB, as well as the tertiary amino analog r-bPiDDB. The current work describes the discovery of r-bPiDI, a tertiary amino, α-conotoxin MII-like small molecule

  14. 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.

  15. Cholinergic nicotinic receptor genes implicated in a nicotine dependence association study targeting 348 candidate genes with 3713 SNPs.

    Science.gov (United States)

    Saccone, Scott F; Hinrichs, Anthony L; Saccone, Nancy L; Chase, Gary A; Konvicka, Karel; Madden, Pamela A F; Breslau, Naomi; Johnson, Eric O; Hatsukami, Dorothy; Pomerleau, Ovide; Swan, Gary E; Goate, Alison M; Rutter, Joni; Bertelsen, Sarah; Fox, Louis; Fugman, Douglas; Martin, Nicholas G; Montgomery, Grant W; Wang, Jen C; Ballinger, Dennis G; Rice, John P; Bierut, Laura Jean

    2007-01-01

    Nicotine dependence is one of the world's leading causes of preventable death. To discover genetic variants that influence risk for nicotine dependence, we targeted over 300 candidate genes and analyzed 3713 single nucleotide polymorphisms (SNPs) in 1050 cases and 879 controls. The Fagerström test for nicotine dependence (FTND) was used to assess dependence, in which cases were required to have an FTND of 4 or more. The control criterion was strict: control subjects must have smoked at least 100 cigarettes in their lifetimes and had an FTND of 0 during the heaviest period of smoking. After correcting for multiple testing by controlling the false discovery rate, several cholinergic nicotinic receptor genes dominated the top signals. The strongest association was from an SNP representing CHRNB3, the beta3 nicotinic receptor subunit gene (P = 9.4 x 10(-5)). Biologically, the most compelling evidence for a risk variant came from a non-synonymous SNP in the alpha5 nicotinic receptor subunit gene CHRNA5 (P = 6.4 x 10(-4)). This SNP exhibited evidence of a recessive mode of inheritance, resulting in individuals having a 2-fold increase in risk of developing nicotine dependence once exposed to cigarette smoking. Other genes among the top signals were KCNJ6 and GABRA4. This study represents one of the most powerful and extensive studies of nicotine dependence to date and has found novel risk loci that require confirmation by replication studies.

  16. Primary Structure of Nicotinic Acetylcholine Receptor

    Science.gov (United States)

    1986-08-01

    quantities of starting material (for reviews of receptor, see Popot and Changeux, 1984; Stroud and Finer-Moore, 1985). This work led to the...Cloning of the Acetylcholine Receptor. Cold Spring Harbor Symp. on Quant. Biol. XLVIH: 71-78. 15. Popot , J-L. and Changeux, J-P. (1984) The

  17. A choreography of nicotinic receptors directs the dopamine neuron routine.

    Science.gov (United States)

    Ungless, Mark A; Cragg, Stephanie J

    2006-06-15

    Modulation of the mesocorticolimbic dopamine system by nicotinic acetylcholine receptors (nAChRs) is thought to play an important role in both health and addiction. However, a clear understanding of how these receptors regulate in vivo firing activity has been elusive. In this issue of Neuron, Mameli-Engvall and colleagues report an impressive and thought-provoking series of in vivo experiments combining single-unit recordings from dopamine neurons with nAChR subunit deletions and region-specific lentiviral subunit re-expression.

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

    DEFF Research Database (Denmark)

    Thomsen, Morten Skøtt; Andreasen, Jesper Tobias; 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...

  19. Flupyrimin: A Novel Insecticide Acting at the Nicotinic Acetylcholine Receptors.

    Science.gov (United States)

    Onozaki, Yasumichi; Horikoshi, Ryo; Ohno, Ikuya; Kitsuda, Shigeki; Durkin, Kathleen A; Suzuki, Tomonori; Asahara, Chiaki; Hiroki, Natsuko; Komabashiri, Rena; Shimizu, Rikako; Furutani, Shogo; Ihara, Makoto; Matsuda, Kazuhiko; Mitomi, Masaaki; Kagabu, Shinzo; Uomoto, Katsuhito; Tomizawa, Motohiro

    2017-09-13

    A novel chemotype insecticide flupyrimin (FLP) [N-[(E)-1-(6-chloro-3-pyridinylmethyl)pyridin-2(1H)-ylidene]-2,2,2-trifluoroacetamide], discovered by Meiji Seika Pharma, has unique biological properties, including outstanding potency to imidacloprid (IMI)-resistant rice pests together with superior safety toward pollinators. Intriguingly, FLP acts as a nicotinic antagonist in American cockroach neurons, and [(3)H]FLP binds to the multiple high-affinity binding components in house fly nicotinic acetylcholine (ACh) receptor (nAChR) preparation. One of the [(3)H]FLP receptors is identical to the IMI receptor, and the alternative is IMI-insensitive subtype. Furthermore, FLP is favorably safe to rats as predicted by the very low affinity to the rat α4β2 nAChR. Structure-activity relationships of FLP analogues in terms of receptor potency, featuring the pyridinylidene and trifluoroacetyl pharmacophores, were examined, thereby establishing the FLP molecular recognition at the Aplysia californica ACh-binding protein, a suitable structural surrogate of the insect nAChR. These FLP pharmacophores account for the excellent receptor affinity, accordingly revealing differences in its binding mechanism from IMI.

  20. SAR of α7 nicotinic receptor agonists derived from tilorone: exploration of a novel nicotinic pharmacophore.

    Science.gov (United States)

    Schrimpf, Michael R; Sippy, Kevin B; Briggs, Clark A; Anderson, David J; Li, Tao; Ji, Jianguo; Frost, Jennifer M; Surowy, Carol S; Bunnelle, William H; Gopalakrishnan, Murali; Meyer, Michael D

    2012-02-15

    The well-known interferon-inducer tilorone was found to possess potent affinity for the agonist site of the α7 neuronal nicotinic receptor (K(i)=56 nM). SAR investigations determined that both basic sidechains are essential for potent activity, however active monosubstituted derivatives can also be prepared if the flexible sidechains are replaced with conformationally rigidified cyclic amines. Analogs in which the fluorenone core is replaced with either dibenzothiophene-5,5-dioxide or xanthenone also retain potent activity.

  1. Nicotinic acetylcholine receptors controlling attention: behavior, circuits and sensitivity to disruption by nicotine.

    Science.gov (United States)

    Poorthuis, Rogier B; Mansvelder, Huibert D

    2013-10-15

    Attention is a central cognitive function that enables long-term engagement in a task and suppression of irrelevant information to obtain future goals. The prefrontal cortex (PFC) is the main link in integrating emotional and motivational state of an animal to regulate top-down attentional processes. Acetylcholine modulates PFC neuronal networks by activating nicotinic acetylcholine receptors (nAChRs) to support attention. However, how neuronal activity changes in the PFC during attention and which nAChR subtypes mediate this is only rudimentarily understood, but progress is being made. Recently, exciting new insights were obtained in the dynamics of cholinergic signaling in the PFC and modes of acetylcholine transmission via nAChRs in the cortex. In addition, mechanisms are uncovered on how the PFC circuitry is regulated by nAChRs. Novel studies show that endogenous activation of nAChRs in the PFC plays a central role in controlling attention. Here, we review current insights into how different subtypes of nAChRs expressed by distinct types of neurons in the PFC circuitry shape attention. In addition we discuss the impact of nicotine on the cholinergic system and prefrontal cortical circuits. Low concentrations of nicotine, as experienced by smokers, interfere with cholinergic signaling. In the long-term exposure to nicotine during adolescence leads to maladaptive adaptations of the PFC circuitry, which ultimately leads to a decrement in attention performance, again emphasizing the importance of nAChRs in attention. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Cytisine induces autonomic cardiovascular responses via activations of different nicotinic receptors.

    Science.gov (United States)

    Li, Yi-Fan; Lacroix, Carly; Freeling, Jessica

    2010-04-19

    Nicotinic cholinergic receptors mediate autonomic transmission at ganglia. However, whether different subtypes of nicotinic cholinergic receptors expressed in autonomic ganglia elicit distinct roles in mediating sympathetic and parasympathetic regulations remain to be defined. In this study, we observed that different subtypes of nicotinic receptors were responsible for the sympathetic and parasympathetic cardiovascular responses. In urethane anesthetized mice, intravenous injection with cytisine, a non-selective nicotinic agonist, induced a brief but pronounced decrease in heart rate, followed by increases in heart rate and arterial blood pressure. The bradycardic response was blocked by atropine, and the pressor response was blocked by prazosin, confirming that these responses were parasympathetic and sympathetic activities, respectively. Hexamethonium, a ganglionic blocker, blocked both sympathetic and parasympathetic responses. Pretreatment with methyllycaconitine citrate, a selective alpha7 nicotinic receptor antagonist, significantly attenuated cytisine-induced sympathetic response with little effect on the parasympathetic response. In contrast, pretreatment with dihydro-beta-erythroidine hydrobromide, a selective alpha4beta2 nicotinic receptor antagonist, blocked cytisine-induced parasympathetic response but not the sympathetic response. Pretreatment with dihydro-beta-erythroidine hydrobromide also blocked baroreflex associated parasympathetic bradycardic response. Moreover, treatment with nicotine induced a bradycardic response without a significant pressor response, which was also attenuated by dihydro-beta-erythroidine hydrobromide. Collectively, these data suggest that different nicotinic receptors play distinct roles in sympathetic and parasympathetic ganglia. Specifically, activations of alpha7 and alpha4beta2 nicotinic receptors are involved in cytisine-induced cardiovascular sympathetic and parasympathetic responses, respectively.

  3. Megakaryocytes and platelets express nicotinic acetylcholine receptors but nicotine does not affect megakaryopoiesis or platelet function.

    Science.gov (United States)

    Schedel, Angelika; Kaiser, Kerstin; Uhlig, Stefanie; Lorenz, Florian; Sarin, Anip; Starigk, Julian; Hassmann, Dennis; Bieback, Karen; Bugert, Peter

    2016-01-01

    In our previous investigations we have shown that platelets and their precursors express nicotinic α7 acetylcholine receptors (nAChRα7) that are involved in platelet function and in vitro differentiation of the megakaryoblastic cell line MEG-01. In this study, we were interested in the expression analysis of additional nAChR and the effects of nicotine in an ex vivo model using megakaryocytic cells differentiated from cord blood derived CD34(+) cells (CBMK) and an in vivo model using blood samples from smokers. CBMK were differentiated with thrombopoietin (TPO) for up to 17 days. Quantitative real-time PCR (QRT-PCR), Western blot analysis and flow cytometry were used to investigate nAChR expression (nAChRα7, nAChRα4, nAChRβ2) and nicotine effects. In blood samples of 15 nonsmokers and 16 smokers platelet parameters (count, mean platelet volume--MPV and platelet distribution width--PDW) were determined as indicators for changes of in vivo megakaryopoiesis. Platelet function was determined by the use of whole blood aggregometry and flow cytometry. The functional role of nAChR was evaluated using specific antagonists in aggregometry. CHRNA7, CHRNA4 and CHRNB2 gene transcripts and the corresponding proteins could be identified in CBMK during all stages of differentiation. Platelets contain nAChRα7 and nAChRβ2 but not nAChRα4. Nicotine had no effect on TPO-induced differentiation of CBMK. There was no significant difference in all platelet parameters of the smokers compared to the nonsmokers. In line with this, cholinergic gene transcripts as well as the encoded proteins were equally expressed in both the study groups. Despite our observation of nAChR expression in megakaryopoiesis and platelets, we were not able to detect effects of nicotine in our ex vivo and in vivo models. Thus, the functional role of the nAChR in these cells remains open.

  4. 4 subunit of nicotinic acetylcholine receptor polymorphisms exhibit ...

    African Journals Online (AJOL)

    A.B. Ruzilawati

    2015-09-06

    Sep 6, 2015 ... nicotine dependence (3–4), moderate nicotine dependence (5), high nicotine ..... transporter gene polymorphism 5- · HTTLPR and smoking among Polish population: a case–control .... Arch Gen Psychiatry · 2007;64:1078–86.

  5. Scopolamine administration modulates muscarinic, nicotinic and NMDA receptor systems.

    Directory of Open Access Journals (Sweden)

    Soheil Keihan Falsafi

    Full Text Available Studies on the effect of scopolamine on memory are abundant but so far only regulation of the muscarinic receptor (M1 has been reported. We hypothesized that levels of other cholinergic brain receptors as the nicotinic receptors and the N-methyl-D-aspartate (NMDA receptor, known to be involved in memory formation, would be modified by scopolamine administration.C57BL/6J mice were used for the experiments and divided into four groups. Two groups were given scopolamine 1 mg/kg i.p. (the first group was trained and the second group untrained in the multiple T-maze (MTM, a paradigm for evaluation of spatial memory. Likewise, vehicle-treated mice were trained or untrained thus serving as controls. Hippocampal levels of M1, nicotinic receptor alpha 4 (Nic4 and 7 (Nic7 and subunit NR1containing complexes were determined by immunoblotting on blue native gel electrophoresis.Vehicle-treated trained mice learned the task and showed memory retrieval on day 8, while scopolamine-treatment led to significant impairment of performance in the MTM. At the day of retrieval, hippocampal levels for M1, Nic7 and NR1 were higher in the scopolamine treated groups than in vehicle-treated groups.The concerted action, i.e. the pattern of four brain receptor complexes regulated by the anticholinergic compound scopolamine, is shown. Insight into probable action mechanisms of scopolamine at the brain receptor complex level in the hippocampus is provided. Scopolamine treatment is a standard approach to test cognitive enhancers and other psychoactive compounds in pharmacological studies and therefore knowledge on mechanisms is of pivotal interest.

  6. Optochemical control of genetically engineered neuronal nicotinic acetylcholine receptors

    Science.gov (United States)

    Tochitsky, Ivan; Banghart, Matthew R.; Mourot, Alexandre; Yao, Jennifer Z.; Gaub, Benjamin; Kramer, Richard H.; Trauner, Dirk

    2012-02-01

    Advances in synthetic chemistry, structural biology, molecular modelling and molecular cloning have enabled the systematic functional manipulation of transmembrane proteins. By combining genetically manipulated proteins with light-sensitive ligands, innately ‘blind’ neurobiological receptors can be converted into photoreceptors, which allows them to be photoregulated with high spatiotemporal precision. Here, we present the optochemical control of neuronal nicotinic acetylcholine receptors (nAChRs) with photoswitchable tethered agonists and antagonists. Using structure-based design, we produced heteromeric α3β4 and α4β2 nAChRs that can be activated or inhibited with deep-violet light, but respond normally to acetylcholine in the dark. The generation of these engineered receptors should facilitate investigation of the physiological and pathological functions of neuronal nAChRs and open a general pathway to photosensitizing pentameric ligand-gated ion channels.

  7. Cell-surface translational dynamics of nicotinic acetylcholine receptors

    Directory of Open Access Journals (Sweden)

    Francisco J Barrantes

    2014-11-01

    Full Text Available Synapse efficacy heavily relies on the number of neurotransmitter receptors available at a given time. In addition to the equilibrium between the biosynthetic production, exocytic delivery and recycling of receptors on the one hand, and the endocytic internalization on the other, lateral diffusion and clustering of receptors at the cell membrane play key roles in determining the amount of active receptors at the synapse. Mobile receptors traffic between reservoir compartments and the synapse by thermally driven Brownian motion, and become immobilized at the peri-synaptic region or the synapse by: a clustering mediated by homotropic inter-molecular receptor-receptor associations; b heterotropic associations with non-receptor scaffolding proteins or the subjacent cytoskeletal meshwork, leading to diffusional trapping, and c protein-lipid interactions, particularly with the neutral lipid cholesterol. This review assesses the contribution of some of these mechanisms to the supramolecular organization and dynamics of the paradigm neurotransmitter receptor of muscle and neuronal cells -the nicotinic acetylcholine receptor (nAChR. Currently available information stemming from various complementary biophysical techniques commonly used to interrogate the dynamics of cell-surface components is critically discussed. The translational mobility of nAChRs at the cell surface differs between muscle and neuronal receptors in terms of diffusion coefficients and residence intervals at the synapse, which cover an ample range of time regimes. A peculiar feature of brain 7 nAChR is its ability to spend much of its time confined peri-synaptically, vicinal to glutamatergic (excitatory and GABAergic (inhibitory synapses. An important function of the 7 nAChR may thus be visiting the territories of other neurotransmitter receptors, differentially regulating the dynamic equilibrium between excitation and inhibition, depending on its residence time in each domain.

  8. NMDA receptors regulate nicotine-enhanced brain reward function and intravenous nicotine self-administration: role of the ventral tegmental area and central nucleus of the amygdala.

    Science.gov (United States)

    Kenny, Paul J; Chartoff, Elena; Roberto, Marisa; Carlezon, William A; Markou, Athina

    2009-01-01

    Nicotine is considered an important component of tobacco responsible for the smoking habit in humans. Nicotine increases glutamate-mediated transmission throughout brain reward circuitries. This action of nicotine could potentially contribute to its intrinsic rewarding and reward-enhancing properties, which motivate consumption of the drug. Here we show that the competitive N-methyl-D-aspartate (NMDA) receptor antagonist LY235959 (0.5-2.5 mg per kg) abolished nicotine-enhanced brain reward function, reflected in blockade of the lowering of intracranial self-stimulation (ICSS) thresholds usually observed after experimenter-administered (0.25 mg per kg) or intravenously self-administered (0.03 mg per kg per infusion) nicotine injections. The highest LY235959 dose (5 mg per kg) tested reversed the hedonic valence of nicotine from positive to negative, reflected in nicotine-induced elevations of ICSS thresholds. LY235959 doses that reversed nicotine-induced lowering of ICSS thresholds also markedly decreased nicotine self-administration without altering responding for food reinforcement, whereas the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor antagonist NBQX had no effects on nicotine intake. In addition, nicotine self-administration upregulated NMDA receptor subunit expression in the central nucleus of the amygdala (CeA) and ventral tegmental area (VTA), suggesting important interactions between nicotine and the NMDA receptor. Furthermore, nicotine (1 microM) increased NMDA receptor-mediated excitatory postsynaptic currents in rat CeA slices, similar to its previously described effects in the VTA. Finally, infusion of LY235959 (0.1-10 ng per side) into the CeA or VTA decreased nicotine self-administration. Taken together, these data suggest that NMDA receptors, including those in the CeA and VTA, gate the magnitude and valence of the effects of nicotine on brain reward systems, thereby regulating motivation to consume the drug.

  9. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    Science.gov (United States)

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo." The pattern evok...

  10. 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.

  11. Thyroid receptor β involvement in the effects of acute nicotine on hippocampus-dependent memory.

    Science.gov (United States)

    Leach, Prescott T; Kenney, Justin W; Connor, David A; Gould, Thomas J

    2015-06-01

    Cigarette smoking is common despite adverse health effects. Nicotine's effects on learning may contribute to addiction by enhancing drug-context associations. Effects of nicotine on learning could be direct or could occur by altering systems that modulate cognition. Because thyroid signaling can alter cognition and nicotine/smoking may change thyroid function, nicotine could affect learning through changes in thyroid signaling. These studies investigate the functional contributions of thyroid receptor (TR) subtypes β and α1 to nicotine-enhanced learning and characterize the effects of acute nicotine and learning on thyroid hormone levels. We conducted a high throughput screen of transcription factor activity to identify novel targets that may contribute to the effects of nicotine on learning. Based on these results, which showed that combined nicotine and learning uniquely acted to increase TR activation, we identified TRs as potential targets of nicotine. Further analyses were conducted to determine the individual and combined effects of nicotine and learning on thyroid hormone levels, but no changes were seen. Next, to determine the role of TRβ and TRα1 in the effects of nicotine on learning, mice lacking the TRβ or TRα1 gene and wildtype littermates were administered acute nicotine prior to fear conditioning. Nicotine enhanced contextual fear conditioning in TRα1 knockout mice and wildtypes from both lines but TRβ knockout mice did not show nicotine-enhanced learning. This finding supports involvement of TRβ signaling in the effect of acute nicotine on hippocampus-dependent memory. Acute nicotine enhances learning and these effects may involve processes regulated by the transcription factor TRβ.

  12. Gold nanoparticle–choline complexes can block nicotinic acetylcholine receptors

    Directory of Open Access Journals (Sweden)

    Chur Chin

    2010-04-01

    Full Text Available Chur Chin1, In Kyeom Kim2, Dong Yoon Lim3, Ki Suk Kim4, Hyang Ae Lee4, Eun Joo Kim41Department of Pediatrics, Fatima Hospital, Daegu, Korea; 2Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, Korea; 3Department of Pharmacology, School of Medicine, Chosun University, Gwangju, Korea; 4Korea Institute of Toxicology, Daejeon, KoreaAbstract: We identified a novel class of direct ion-channel blockers of ligand-gated ion channels called the gold nanoparticle–choline complex. Negatively charged gold nanoparticles (1.4 nm block ion pores by binding to the sulfur group of the cysteine loop of nicotinic acetylcholine receptors (nAChRs, and currents evoked by acetylcholine (Ach can break these bonds. The current evoked by ACh in nAChRs was blocked directly in ion pores by the gold nanoparticle–choline complex. In adrenal-gland perfusion studies, the complex also blocked nAChRs by diminishing catecholamine release by about 75%. An in vivo study showed muscle relaxation in rats after injection of the complex. These results will foster the application of gold nanoparticles as a direct ion-channel blocker. Keywords: negatively charged gold nanoparticle, choline, gold–sulfur bond, nicotinic acetylcholine receptor, direct ion-channel blocker

  13. Effect of repeated nicotine exposure on high-affinity nicotinic acetylcholine receptor density in spontaneously hypertensive rats.

    Science.gov (United States)

    Hohnadel, Elizabeth J; Hernandez, Caterina M; Gearhart, Debra A; Terry, Alvin V

    Spontaneously hypertensive rats (SHRs) are often used as a model of attention deficit hyperactivity disorder (ADHD) and to investigate the effects of hypertension on cognitive function. Further, they appear to have reduced numbers of central nicotinic acetylcholine receptors (nAChRs) and, therefore, may be useful to model certain aspects of Alzheimer's disease (AD) and other forms of dementia given that a decrease in nAChRs is thought to contribute to cognitive decline in these disorders. In the present study, based on reports that chronic nicotine exposure increases nAChRs in several mammalian models, we tested the hypothesis that repeated exposures to a relatively low dose of the alkaloid would ameliorate the receptor deficits in SHR. Thus, young-adult SHRs and age-matched Wistar-Kyoto (WKY) control rats were treated with either saline or nicotine twice a day for 14 days (total daily dose = 0.7 mg/kg nicotine base) and then sacrificed. Quantitative receptor autoradiography with [125I]-IPH, an epibatidine analog, revealed: (1) that high-affinity nAChRs were higher in saline-treated WKY (control) rats compared to saline-treated SHRs in 18 of the 19 brain region measured, although statistically different only in the mediodorsal thalamic nuclei, (2) that nicotine significantly increased nAChR binding in WKY rats in six brain areas including cortical regions and the anterior thalamic nucleus, (3) that there were no cases where nicotine significantly increased nAChR binding in SHRs. These results indicate that subjects deficient in nAChRs may be less sensitive to nAChR upregulation with nicotine than normal subjects and require higher doses or longer periods of exposure.

  14. The role of nicotinic acetylcholine receptors in the primary reinforcing and reinforcement-enhancing effects of nicotine.

    Science.gov (United States)

    Palmatier, Matthew I; Liu, Xiu; Caggiula, Anthony R; Donny, Eric C; Sved, Alan F

    2007-05-01

    The primary reinforcing effects of nicotine are mediated by the drugs action at central nervous system nicotinic acetylcholine receptors (nAChRs). Although previous studies have demonstrated that nicotine potently enhances responding for non-pharmacological stimuli, the role of nAChRs in this reinforcement-enhancing effect is not known. The two reinforcement-related effects of nicotine can be dissociated in a paradigm that provides concurrent access to drug infusions and a non-pharmacological visual stimulus (VS). The present study characterized the role of nAChRs in the primary reinforcing effect of nicotine and the reinforcement-enhancing effect of nicotine. For rats with access to VS (VS-Only), nicotine (NIC-Only), both reinforcers contingent upon one response (NIC+VS) or both reinforcers contingent upon separate responses (2-Lever), unit dose-response relationships (0, 30, 60, or 90 microg/kg/infusion, free base) were determined over a 22-day acquisition period. Expression of the two reinforcement-related effects of nicotine was manipulated by pharmacological antagonism of nAChRs (1 mg/kg mecamylamine, subcutaneous, 5-min before the session) or by substituting saline for nicotine infusions (ie extinction) over a series of seven test sessions. Unit dose manipulations yielded an inverse dose-response relationship for active lever responding in the NIC+VS group. The dose-response relationships for rats with independent access to each reinforcer (2-Lever group) were relatively flat. For the 2-Lever group, acute mecamylamine challenge blocked the reinforcement-enhancing effects of nicotine, VS-lever responding decreased to basal levels on the first day of mecamylamine treatment or saline substitution (to the level of the VS-Only group). In contrast, nicotine-lever responding decreased gradually over the 7-day testing period (similar to saline extinction). The two reinforcement-related effects of nicotine are mediated by nAChRs but can be dissociated by acute and

  15. Activation of α7-containing nicotinic receptors on astrocytes triggers AMPA receptor recruitment to glutamatergic synapses.

    Science.gov (United States)

    Wang, Xulong; Lippi, Giordano; Carlson, David M; Berg, Darwin K

    2013-12-01

    Astrocytes, an abundant form of glia, are known to promote and modulate synaptic signaling between neurons. They also express α7-containing nicotinic acetylcholine receptors (α7-nAChRs), but the functional relevance of these receptors is unknown. We show here that stimulation of α7-nAChRs on astrocytes releases components that induce hippocampal neurons to acquire more α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors post-synaptically at glutamatergic synapses. The increase is specific in that no change is seen in synaptic NMDA receptor clusters or other markers for glutamatergic synapses, or in markers for GABAergic synapses. Moreover, the increases in AMPA receptors on the neuron surface are accompanied by increases in the frequency of spontaneous miniature synaptic currents mediated by the receptors and increases in the ratio of evoked synaptic currents mediated by AMPA versus NMDA receptors. This suggests that stimulating α7-nAChRs on astrocytes can convert 'silent' glutamatergic synapses to functional status. Astrocyte-derived thrombospondin is necessary but not sufficient for the effect, while tumor necrosis factor-α is sufficient but not necessary. The results identify astrocyte α7-nAChRs as a novel pathway through which nicotinic cholinergic signaling can promote the development of glutamatergic networks, recruiting AMPA receptors to post-synaptic sites and rendering the synapses more functional. We find that activation of nicotinic receptors on astrocytes releases a component that specifically recruits AMPA receptors to glutamatergic synapses. The recruitment appears to occur preferentially at what may be 'silent synapses', that is, synapses that have all the components required for glutamatergic transmission (including NMDA receptors) but lack sufficient AMPA receptors to generate a response. The results are unexpected and open up new possibilities for mechanisms underlying network formation and synaptic plasticity.

  16. Targeted deletion of the mouse α2 nicotinic acetylcholine receptor subunit gene (Chrna2) potentiates nicotine-modulated behaviors.

    Science.gov (United States)

    Lotfipour, Shahrdad; Byun, Janet S; Leach, Prescott; Fowler, Christie D; Murphy, Niall P; Kenny, Paul J; Gould, Thomas J; Boulter, Jim

    2013-05-01

    Baseline and nicotine-modulated behaviors were assessed in mice harboring a null mutant allele of the nicotinic acetylcholine receptor (nAChR) subunit gene α2 (Chrna2). Homozygous Chrna2(-/-) mice are viable, show expected sex and Mendelian genotype ratios, and exhibit no gross neuroanatomical abnormalities. A broad range of behavioral tests designed to assess genotype-dependent effects on anxiety (elevated plus maze and light/dark box), motor coordination (narrow bean traverse and gait), and locomotor activity revealed no significant differences between mutant mice and age-matched wild-type littermates. Furthermore, a panel of tests measuring traits, such as body position, spontaneous activity, respiration, tremors, body tone, and startle response, revealed normal responses for Chrna2-null mutant mice. However, Chrna2(-/-) mice do exhibit a mild motor or coordination phenotype (a decreased latency to fall during the accelerating rotarod test) and possess an increased sensitivity to nicotine-induced analgesia in the hotplate assay. Relative to wild-type, Chrna2(-/-) mice show potentiated nicotine self-administration and withdrawal behaviors and exhibit a sex-dependent enhancement of nicotine-facilitated cued, but not trace or contextual, fear conditioning. Overall, our results suggest that loss of the mouse nAChR α2 subunit has very limited effects on baseline behavior but does lead to the potentiation of several nicotine-modulated behaviors.

  17. Molecular identification of high and low affinity receptors for nicotinic acid.

    Science.gov (United States)

    Wise, Alan; Foord, Steven M; Fraser, Neil J; Barnes, Ashley A; Elshourbagy, Nabil; Eilert, Michelle; Ignar, Diane M; Murdock, Paul R; Steplewski, Klaudia; Green, Andrew; Brown, Andrew J; Dowell, Simon J; Szekeres, Philip G; Hassall, David G; Marshall, Fiona H; Wilson, Shelagh; Pike, Nicholas B

    2003-03-14

    Nicotinic acid has been used clinically for over 40 years in the treatment of dyslipidemia producing a desirable normalization of a range of cardiovascular risk factors, including a marked elevation of high density lipoprotein and a reduction in mortality. The precise mechanism of action of nicotinic acid is unknown, although it is believed that activation of a G(i)-G protein-coupled receptor may contribute. Utilizing available information on the tissue distribution of nicotinic acid receptors, we identified candidate orphan receptors. The selected orphan receptors were screened for responses to nicotinic acid, in an assay for activation of G(i)-G proteins. Here we describe the identification of the G protein-coupled receptor HM74 as a low affinity receptor for nicotinic acid. We then describe the subsequent identification of HM74A in follow-up bioinformatics searches and demonstrate that it acts as a high affinity receptor for nicotinic acid and other compounds with related pharmacology. The discovery of HM74A as a molecular target for nicotinic acid may facilitate the discovery of superior drug molecules to treat dyslipidemia.

  18. C3-halogenation of cytisine generates potent and efficacious nicotinic receptor agonists.

    Science.gov (United States)

    Abin-Carriquiry, J Andrés; Voutilainen, Merja H; Barik, Jacques; Cassels, Bruce K; Iturriaga-Vásquez, Patricio; Bermudez, Isabel; Durand, Claudia; Dajas, Federico; Wonnacott, Susan

    2006-04-24

    Neuronal nicotinic acetylcholine receptors subserve predominantly modulatory roles in the brain, making them attractive therapeutic targets. Natural products provide key leads in the quest for nicotinic receptor subtype-selective compounds. Cytisine, found in Leguminosae spp., binds with high affinity to alpha4beta2* nicotinic receptors. We have compared the effect of C3 and C5 halogenation of cytisine and methylcytisine (MCy) on their interaction with native rat nicotinic receptors. 3-Bromocytisine (3-BrCy) and 3-iodocytisine (3-ICy) exhibited increased binding affinity (especially at alpha7 nicotinic receptors; Ki approximately 0.1 microM) and functional potency, whereas C5-halogenation was detrimental. 3-BrCy and 3-ICy were more potent than cytisine at evoking [3H]dopamine release from striatal slices (EC50 approximately 11 nM), [3H]noradrenaline release from hippocampal slices (EC50 approximately 250 nM), increases in intracellular Ca2+ in PC12 cells and inward currents in Xenopus oocytes expressing human alpha3beta4 nicotinic receptor (EC50 approximately 2 microM). These compounds were also more efficacious than cytisine. C3-halogenation of cytisine is proposed to stabilize the open conformation of the nicotinic receptor but does not enhance subtype selectivity.

  19. Using growth models to relate acquisition of nicotine self-administration to break point and nicotinic receptor binding.

    Science.gov (United States)

    Donny, Eric C; Lanza, Stephanie T; Balster, Robert L; Collins, Linda M; Caggiula, Anthony; Rowell, Peter P

    2004-07-15

    Growth modeling can be used to characterize individual and mean acquisition trajectories for drug self-administration. Individual characteristics can also be incorporated into the growth model, providing a powerful tool for investigating the relationship between acquisition and other behavioral and biological measures. We illustrate the utility of this method by examining the relationship between acquisition of nicotine self-administration and (1) break point on a progressive ratio schedule of reinforcement, and (2) the density of brain nicotinic receptors (B(max)). Daily infusion rates from male and female Sprague-Dawley rats were modeled with break point or B(max) as time-invariant covariates. Use of this model led to two novel findings regarding individual differences in acquisition. First, greater rates of change in infusions early in acquisition were related to higher break points; this relationship was mediated by a similar effect of increasing the number of responses required to obtain nicotine. Second, animals displaying more resistance to increases in the response requirement during acquisition, as indicated by a smaller drop in the rate of nicotine self-administration, generally had fewer nicotinic receptors at the end of the experiment. The relationships revealed demonstrate the usefulness of growth models in the quantitative analysis of individual differences in drug self-administration behavior.

  20. Nicotinic acetylcholine receptor α7 subunits with a C2 cytoplasmic loop yellow fluorescent protein insertion form functional receptors

    Institute of Scientific and Technical Information of China (English)

    Teresa A MURRAY; Qiang LIU; Paul WHITEAKER; Jie WU; Ronald J LUKAS

    2009-01-01

    Aim: Several nicotinic acetylcholine receptor (nAChR) subunits have been engineered as fluorescent protein (FP) fusions and exploited to illuminate features of nAChRs. The aim of this work was to create a FP fusion in the nAChR a.7 subunit without compromising formation of functional receptors.Methods: A gene construct was generated to introduce yellow fluorescent protein (YFP), in frame, into the otherwise unaltered, large, second cytoplamsic loop between the third and fourth transmembrane domains of the mouse nAChR al sub-unit (a7Y). SH-EP1 cells were transfected with mouse nAChR wild type a.7 subunits (a.7) or with a7Y subunits, alone or with the chaperone protein, hRJC-3. Receptor function was assessed using whole-cell current recording. Receptor expression was measured with 125I-labeled a-bungarotoxin (I-Bgt) binding, laser scanning confocal microscopy, and total internal reflectance fluorescence (TIRF) microscopy.Results: Whole-cell currents revealed that a7Y nAChRs and al nAChRs were functional with comparable EC50 values for the a7 nAChR-selective agonist, choline, and IC50 values for the a.7 nAChR-selective antagonist, methyllycaconitine. I-Bgt binding was detected only after co-expression with hRIC-3. Confocal microscopy revealed that a7Y had primarily intracel-lular rather than surface expression. TIRF microscopy confirmed that little a7Y localized to the plasma membrane, typical of a7 nAChRs.Conclusion: nAChRs composed as homooligomers of a7Y subunits containing cytoplasmic loop YFP have functional, ligand binding, and trafficking characteristics similar to those of a.7 nAChRs. a7Y nAChRs may be used to elucidate properties of a.7 nAChRs and to identify and develop novel probes for these receptors, perhaps in high-throughput fashion.

  1. 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

    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...

  2. 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 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 [(125)I] 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.

  3. 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.

  4. Erythrina mulungu alkaloids are potent inhibitors of neuronal nicotinic receptor currents in mammalian cells.

    Directory of Open Access Journals (Sweden)

    Pedro Setti-Perdigão

    Full Text Available Crude extracts and three isolated alkaloids from Erythrina mulungu plants have shown anxiolytic effects in different animal models. We investigated whether these alkaloids could affect nicotinic acetylcholine receptors and if they are selective for different central nervous system (CNS subtypes. Screening experiments were performed using a single concentration of the alkaloid co-applied with acetylcholine in whole cell patch-clamp recordings in three different cell models: (i PC12 cells natively expressing α3* nicotinic acetylcholine receptors; (ii cultured hippocampal neurons natively expressing α7* nicotinic acetylcholine receptors; and (iii HEK 293 cells heterologoulsy expressing α4β2 nicotinic acetylcholine receptors. For all three receptors, the percent inhibition of acetylcholine-activated currents by (+-11á-hydroxyerysotrine was the lowest, whereas (+-erythravine and (+-11á-hydroxyerythravine inhibited the currents to a greater extent. For the latter two substances, we obtained concentration-response curves with a pre-application protocol for the α7* and α4β2 nicotinic acetylcholine receptors. The IC50 obtained with (+-erythravine and (+-11á-hydroxyerythravine were 6 µM and 5 µM for the α7* receptors, and 13 nM and 4 nM for the α4β2 receptors, respectively. Our data suggest that these Erythrina alkaloids may exert their behavioral effects through inhibition of CNS nicotinic acetylcholine receptors, particularly the α4β2 subtype.

  5. Erythrina mulungu alkaloids are potent inhibitors of neuronal nicotinic receptor currents in mammalian cells.

    Science.gov (United States)

    Setti-Perdigão, Pedro; Serrano, Maria A R; Flausino, Otávio A; Bolzani, Vanderlan S; Guimarães, Marília Z P; Castro, Newton G

    2013-01-01

    Crude extracts and three isolated alkaloids from Erythrina mulungu plants have shown anxiolytic effects in different animal models. We investigated whether these alkaloids could affect nicotinic acetylcholine receptors and if they are selective for different central nervous system (CNS) subtypes. Screening experiments were performed using a single concentration of the alkaloid co-applied with acetylcholine in whole cell patch-clamp recordings in three different cell models: (i) PC12 cells natively expressing α3* nicotinic acetylcholine receptors; (ii) cultured hippocampal neurons natively expressing α7* nicotinic acetylcholine receptors; and (iii) HEK 293 cells heterologoulsy expressing α4β2 nicotinic acetylcholine receptors. For all three receptors, the percent inhibition of acetylcholine-activated currents by (+)-11á-hydroxyerysotrine was the lowest, whereas (+)-erythravine and (+)-11á-hydroxyerythravine inhibited the currents to a greater extent. For the latter two substances, we obtained concentration-response curves with a pre-application protocol for the α7* and α4β2 nicotinic acetylcholine receptors. The IC50 obtained with (+)-erythravine and (+)-11á-hydroxyerythravine were 6 µM and 5 µM for the α7* receptors, and 13 nM and 4 nM for the α4β2 receptors, respectively. Our data suggest that these Erythrina alkaloids may exert their behavioral effects through inhibition of CNS nicotinic acetylcholine receptors, particularly the α4β2 subtype.

  6. Role of nicotine dependence on the relationship between variants in the nicotinic receptor genes and risk of lung adenocarcinoma.

    Directory of Open Access Journals (Sweden)

    Tung-Sung Tseng

    Full Text Available Several variations in the nicotinic receptor genes have been identified to be associated with both lung cancer risk and smoking in the genome-wide association (GWA studies. However, the relationships among these three factors (genetic variants, nicotine dependence, and lung cancer remain unclear. In an attempt to elucidate these relationships, we applied mediation analysis to quantify the impact of nicotine dependence on the association between the nicotinic receptor genetic variants and lung adenocarcinoma risk. We evaluated 23 single nucleotide polymorphisms (SNPs in the five nicotinic receptor related genes (CHRNB3, CHRNA6, and CHRNA5/A3/B4 previously reported to be associated with lung cancer risk and smoking behavior and 14 SNPs in the four 'control' genes (TERT, CLPTM1L, CYP1A1, and TP53, which were not reported in the smoking GWA studies. A total of 661 lung adenocarcinoma cases and 1,347 controls with a smoking history, obtained from the Environment and Genetics in Lung Cancer Etiology case-control study, were included in the study. Results show that nicotine dependence is a mediator of the association between lung adenocarcinoma and gene variations in the regions of CHRNA5/A3/B4 and accounts for approximately 15% of this relationship. The top two CHRNA3 SNPs associated with the risk for lung adenocarcinoma were rs1051730 and rs12914385 (p-value = 1.9×10(-10 and 1.1×10(-10, respectively. Also, these two SNPs had significant indirect effects on lung adenocarcinoma risk through nicotine dependence (p = 0.003 and 0.007. Gene variations rs2736100 and rs2853676 in TERT and rs401681 and rs31489 in CLPTM1L had significant direct associations on lung adenocarcinoma without indirect effects through nicotine dependence. Our findings suggest that nicotine dependence plays an important role between genetic variants in the CHRNA5/A3/B4 region, especially CHRNA3, and lung adenocarcinoma. This may provide valuable information for

  7. 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

  8. The selective dopamine D3 receptor antagonist SB-277011A reduces nicotine-enhanced brain reward and nicotine-paired environmental cue functions.

    Science.gov (United States)

    Pak, Arlene C; Ashby, Charles R; Heidbreder, Christian A; Pilla, Maria; Gilbert, Jeremy; Xi, Zheng-Xiong; Gardner, Eliot L

    2006-10-01

    Increasing evidence suggests that enhanced dopamine (DA) neurotransmission in the nucleus accumbens (NAc) may play a role in mediating the reward and reinforcement produced by addictive drugs and in the attentional processing of drug-associated environmental cues. The meso-accumbens DA system is selectively enriched with DA D3 receptors, a DA receptor subtype increasingly implicated in reward-related brain and behavioural processes. From a variety of evidence, it has been suggested that selective DA D3 receptor antagonism may be a useful pharmacotherapeutic approach for treating addiction. The present experiments tested the efficacy of SB-277011A, a selective DA D3 receptor antagonist, in rat models of nicotine-enhanced electrical brain-stimulation reward (BSR), nicotine-induced conditioned locomotor activity (LMA), and nicotine-induced conditioned place preference (CPP). Nicotine was given subcutaneously within the dose range of 0.25-0.6 mg/kg (nicotine-free base). SB-277011A, given intraperitoneally within the dose range of 1-12 mg/kg, dose-dependently reduced nicotine-enhanced BSR, nicotine-induced conditioned LMA, and nicotine-induced CPP. The results suggest that selective D3 receptor antagonism constitutes a new and promising pharmacotherapeutic approach to the treatment of nicotine dependence.

  9. Nicotine Induces the Production of IL-1ß and IL-8 via the a7 nAChR/NF-κB Pathway in Human Periodontal Ligament Cells: an in Vitro Study

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    Lizheng Wu

    2014-07-01

    Full Text Available Background/Aims: Tobacco smoking is a major risk factor for the occurrence and progression of periodontitis. We previously demonstrated that nicotine could induce the expression of a7 nicotinic acetylcholine receptors (a7 nAChR in human and rat periodontal tissues. To further examine the signal pathways mediated by a7 nAChR in periodontal ligament (PDL cells, we investigated whether nicotine affects interleukin-1ß (IL-1ß and interleukin-8 (IL-8 via the a7 nAChR/NF-κB pathway in human PDL cells. Methods: Human PDL cells were pre-incubated with alpha-bungarotoxin (a-BTX or pyrrolidine dithiocarbamate (PDTC, then cultured with nicotine. Then, we used western blotting, a dual-luciferase reporter, real-time quantitative PCR and an enzyme-linked immunoassay to assess expression of the NF-κB p65 subunit, NF-κB activity and production of IL-1ß and IL-8 in human PDL cells. Results: Compared with the control group, nicotine could significantly induce production of IL-1ß and IL-8 in human PDL cells and cause the similar effects on the expression of the NF-κB p65 subunit and NF-κB activity. Conclusion: This study demonstrates that nicotine could induce production of IL-1ß and IL-8 via the a7 nAChR/NF-κB pathway in human PDL cells, providing data for a better understanding of the relationships among smoking, nicotine, and periodontitis.

  10. Coantagonism of Glutamate Receptors and Nicotinic Acetylcholinergic Receptors Disrupts Fear Conditioning and Latent Inhibition of Fear Conditioning

    Science.gov (United States)

    Gould, Thomas J.; Lewis, Michael C.

    2005-01-01

    The present study investigated the hypothesis that both nicotinic acetylcholinergic receptors (nAChRs) and glutamate receptors ([alpha]-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) and N-methyl-D-aspartate glutamate receptors (NMDARs)) are involved in fear conditioning, and may modulate similar processes. The effects of the…

  11. 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

  12. Functional alpha7 nicotinic receptors are expressed on immature granule cells of the postnatal dentate gyrus.

    Science.gov (United States)

    John, Danielle; Shelukhina, Irina; Yanagawa, Yuchio; Deuchars, Jim; Henderson, Zaineb

    2015-03-19

    Neurogenesis occurs throughout life in the subgranular zone of the dentate gyrus, and postnatal-born granule cells migrate into the granule cell layer and extend axons to their target areas. The α7*nicotinic receptor has been implicated in neuronal maturation during development of the brain and is abundant in interneurons of the hippocampal formation of the adult brain. Signalling through these same receptors is believed also to promote maturation and integration of adult-born granule cells in the hippocampal formation. We therefore aimed to determine whether functional α7*nicotinic receptors are expressed in developing granule cells of the postnatal dentate gyrus. For these experiments we used 2-3 week-old Wistar rats, and 2-9 week old transgenic mice in which GABAergic interneurons were marked by expression of green fluorescent protein. Immunohistochemistry indicated the presence of α7*nicotinic receptor subunits around granule cells close around the subgranular zone which correlated with the distribution of developmental markers for immature granule cells. Whole-cell patch clamp recording showed that a proportion of granule cells responded to puffed ACh in the presence of atropine, and that these cells possessed electrophysiological properties found in immature granule cells. The nicotinic responses were potentiated by an allosteric α7*nicotinic receptor modulator, which were blocked by a specific α7*nicotinic receptor antagonist and were not affected by ionotropic glutamate or GABA receptor antagonists. These results suggest the presence of functional somato-dendritic α7*nicotinic receptors on immature granule cells of the postnatal dentate gyrus, consistent with studies implicating α7*nicotinic receptors in dendritic maturation of dentate gyrus neurons in adult brain. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Activation of the GABAB receptor prevents nicotine-induced locomotor stimulation in mice

    Directory of Open Access Journals (Sweden)

    Carla eLobina

    2011-12-01

    Full Text Available Recent studies demonstrated that activation of the GABAB receptor, either by means of orthosteric agonists or positive allosteric modulators (PAMs, inhibited different nicotine-related behaviors, including intravenous self-administration and conditioned place preference, in rodents. The present study investigated whether the anti-nicotine effects of the GABAB receptor agonist, baclofen, and GABAB PAMs, CGP7930 and GS39783, extend to nicotine stimulant effects. To this end, CD1 mice were initially treated with baclofen (0, 1.25, and 2.5 mg/kg, i.p., CGP7930 (0, 25, and 50 mg/kg, i.g., or GS39783 (0, 25, and 50 mg/kg, i.g., then treated with nicotine (0 and 0.05 mg/kg, s.c., and finally exposed to an automated apparatus for recording of locomotor activity. Pretreatment with doses of baclofen, CGP7930, or GS39783 that did not alter locomotor activity when given with nicotine vehicle fully prevented hyperlocomotion induced by 0.05 mg/kg nicotine. These data extend to nicotine stimulant effects the capacity of baclofen and GABAB PAMs to block the reinforcing, motivational, and rewarding properties of nicotine. These data strengthen the hypothesis that activation of the GABAB receptor may represent a potentially useful, anti-smoking therapeutic strategy.

  14. Neurotransmitter GABA activates muscle but not α7 nicotinic receptors.

    Science.gov (United States)

    Dionisio, Leonardo; Bergé, Ignacio; Bravo, Matías; Esandi, María Del Carmen; Bouzat, Cecilia

    2015-01-01

    Cys-loop receptors are neurotransmitter-activated ion channels involved in synaptic and extrasynaptic transmission in the brain and are also present in non-neuronal cells. As GABAA and nicotinic receptors (nAChR) belong to this family, we explored by macroscopic and single-channel recordings whether the inhibitory neurotransmitter GABA has the ability to activate excitatory nAChRs. GABA differentially activates nAChR subtypes. It activates muscle nAChRs, with maximal peak currents of about 10% of those elicited by acetylcholine (ACh) and 15-fold higher EC50 with respect to ACh. At the single-channel level, the weak agonism is revealed by the requirement of 20-fold higher concentration of GABA for detectable channel openings, a major population of brief openings, and absence of clusters of openings when compared with ACh. Mutations at key residues of the principal binding-site face of muscle nAChRs (αY190 and αG153) affect GABA activation similarly as ACh activation, whereas a mutation at the complementary face (εG57) shows a selective effect for GABA. Studies with subunit-lacking receptors show that GABA can activate muscle nAChRs through the α/δ interface. Interestingly, single-channel activity elicited by GABA is similar to that elicited by ACh in gain-of-function nAChR mutants associated to congenital myasthenic syndromes, which could be important in the progression of the disorders due to steady exposure to serum GABA. In contrast, GABA cannot elicit single-channel or macroscopic currents of α7 or the chimeric α7-serotonin-type 3 receptor, a feature important for preserving an adequate excitatory/inhibitory balance in the brain as well as for avoiding activation of non-neuronal receptors by serum GABA. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  15. Neuronal nicotinic receptors in dementia with Lewy bodies and schizophrenia: alpha-bungarotoxin and nicotine binding in the thalamus.

    Science.gov (United States)

    Court, J; Spurden, D; Lloyd, S; McKeith, I; Ballard, C; Cairns, N; Kerwin, R; Perry, R; Perry, E

    1999-10-01

    Neuronal nicotinic receptors have been implicated in schizophrenia on the basis of the high incidence of tobacco smoking in patients, abnormalities in cytisine and alpha-bungarotoxin (alphaBGT) binding in the hippocampus, and linkage between auditory P50 deficits and the region of chromosome 15 coding the alpha7 subunit. In another disease associated with psychosis, dementia with Lewy bodies (DLB), in which visual hallucinations predominate, reductions in nicotine binding have been identified in various cortical and subcortical regions. We investigated both alphaBGT and nicotine binding autoradiographically in different thalamic nuclei in autopsy brain tissue from patients with schizophrenia and DLB. AlphaBGT binding in the reticular nucleus was moderately reduced (25%) in schizophrenia and more extensively reduced (50%) in DLB. There were no significant alterations in nicotine binding in schizophrenia, and in DLB, a trend towards moderate reductions in most nuclei reached significance in the lateral dorsal nucleus. It is concluded that widespread abnormalities of thalamic nicotine are not implicated in schizophrenia or DLB, but that reticular alphaBGT binding may be involved to a lesser and greater extent in the pathophysiology or psychopathology of both disorders.

  16. 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

  17. 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

  18. Cannabinoid CB1 receptor antagonist rimonabant disrupts nicotine reward-associated memory in rats.

    Science.gov (United States)

    Fang, Qin; Li, Fang-Qiong; Li, Yan-Qin; Xue, Yan-Xue; He, Ying-Ying; Liu, Jian-Feng; Lu, Lin; Wang, Ji-Shi

    2011-10-01

    Exposure to cues previously associated with drug intake leads to relapse by activating previously acquired memories. Based on previous findings, in which cannabinoid CB(1) receptors were found to be critically involved in specific aspects of learning and memory, we investigated the role of CB(1) receptors in nicotine reward memory using a rat conditioned place preference (CPP) model. In Experiment 1, rats were trained for CPP with alternating injections of nicotine (0.5mg/kg, s.c.) and saline to acquire the nicotine-conditioned memory. To examine the effects of rimonabant on the reconsolidation of nicotine reward memory, rats were administered rimonabant (0, 0.3, and 3.0mg/kg, i.p.) immediately after reexposure to the drug-paired context. In Experiment 2, rats were trained for CPP similarly to Experiment 1. To examine the effects of rimonabant on the reinstatement of nicotine reward memory, rimonabant (0, 0.3, and 3.0mg/kg, i.p.) was administered before the test of nicotine-induced CPP reinstatement. In Experiment 3, to evaluate whether rimonabant itself produces a reward memory, rats were trained for CPP with alternating injections of different doses of rimonabant (0, 0.3, and 3.0mg/kg) and saline. Rimonabant at a dose of 3.0mg/kg significantly disrupted the reconsolidation of nicotine memory and significantly blocked the reinstatement of nicotine-induced CPP. However, rimonabant itself did not produce CPP. These findings provide clear evidence that CB(1) receptors play a role in nicotine reward memory, suggesting that CB(1) receptor antagonists may be a potential target for managing nicotine addiction.

  19. 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)

  20. AB318. SPR-45 Decentralization reduces nicotinic receptor-mediated canine bladder contractions in vitro

    Science.gov (United States)

    Salvadeo, Danielle M.; Frara, Nagat; Braverman, Alan S.; Barbe, Mary F.; Ruggieri, Michael R.

    2016-01-01

    Objective Bladder function depends upon several complex signaling pathways that induce either contraction or relaxation. We performed nerve re-routing surgery on bladder of decentralized dogs (reinnervated) as a model with the goal of restoring bladder function in spinal cord injured patients. The neuromuscular nicotinic receptor blocker, succinylcholine blocks spinal root-stimulated bladder contraction in vivo in reinnervated dogs, but not in sham-operated dogs. Our lab explored the function and location of nicotinic receptors involved in bladder contraction, with emphasis on their possible role in the release of other neurotransmitters such as acetylcholine or ATP in sham-operated, 12-month-decentralized and immediate-reinnervated bladders. Methods Smooth muscle strips (mucosa denuded) were isolated from the region just rostral to the trigone and suspended in muscle baths. Strips were ranked based on their contractile response to a 3-min exposure to 120 mM KCl and sorted so that the average response in each group was equal. Strips were incubated with either 1 µM atropine (ATR), 1 µM tetrodotoxin (TTX), 10 µM alpha, beta-methylene ATP (α,β-ATP) or vehicle (water) and then induced to contract with the nicotinic receptor agonists 1,1 dimethyl-4-phenyl-piperazinium iodide (DMPP, 100 µM), TC2559 (100 µM) or epibatidine (10 µM) or 1 mM nicotine itself. Results The DMPP-induced contraction was not different between sham, reinnervated or decentralized bladders (11%, 3.3%, and 3.6% of KCl contraction respectively). While the epibatidine-induced contraction in shams was not different relative to that in the reinnervated (41% vs. 27% KCl respectively), it was significantly greater than that in decentralized bladders (13% of KCl). TC2559 did not induce bladder contractions. Nicotine-induced contractions in sham-operated controls were 16% of KCl. ATR completely blocked nicotine-induced contraction while α,β-ATP had no statistically significant effect in shams. TTX

  1. ( sup 3 H)cytisine binding to nicotinic cholinergic receptors in brain

    Energy Technology Data Exchange (ETDEWEB)

    Pabreza, L.A.; Dhawan, S.; Kellar, K.J. (Georgetown Univ. School of Medicine, Washington, DC (USA))

    1991-01-01

    Cytisine, a ganglionic agonist, competes with high affinity for brain nicotinic cholinergic receptors labeled by any of several nicotinic {sup 3}H-agonist ligands. Here we have examined the binding of ({sup 3}H)cytisine in rat brain homogenates. ({sup 3}H)Cytisine binds with high affinity (Kd less than 1 nM), and specific binding represented 60-90% of total binding at all concentrations examined up to 15 nM. The nicotinic cholinergic agonists nicotine, acetylcholine, and carbachol compete with high affinity for ({sup 3}H)cytisine binding sites, whereas among nicotinic receptor antagonists only dihydro-beta-erythroidine competes with high affinity (in the nanomolar range). Comparison of binding in several brain regions showed that ({sup 3}H)cytisine binding is higher in the thalamus, striatum, and cortex than in the hippocampus, cerebellum, or hypothalamus. The pharmacology and brain regional distribution of ({sup 3}H)cytisine binding sites are those predicted for neuronal nicotinic receptor agonist recognition sites. The high affinity and low nonspecific binding of ({sup 3}H)cytisine should make it a very useful ligand for studying neuronal nicotinic receptors.

  2. Action of nereistoxin on recombinant neuronal nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes.

    Science.gov (United States)

    Raymond Delpech, Valérie; Ihara, Makoto; Coddou, Claudio; Matsuda, Kazuhiko; Sattelle, David B

    2003-11-01

    Nereistoxin (NTX), a natural neurotoxin from the salivary glands of the marine annelid worm Lumbriconereis heteropoda, is highly toxic to insects. Its synthetic analogue, Cartap, was the first commercial insecticide based on a natural product. We have used voltage-clamp electrophysiology to compare the actions of NTX on recombinant nicotinic acetylcholine receptors (nicotinic AChRs) expressed in Xenopus laevis oocytes following nuclear injection of cDNAs. The recombinant nicotinic AChRs investigated were chicken alpha7, chicken alpha4beta2 and the Drosophila melanogaster/chicken hybrid receptors SAD/beta2 and ALS/beta2. No agonist action of NTX (0.1-100 microM) was observed on chicken alpha7, chicken alpha4beta2 and the Drosophila/chicken hybrid nicotinic AChRs. Currents elicited by ACh were reduced in amplitude by NTX in a dose-dependent manner. The toxin was slightly more potent on recombinant Drosophila/vertebrate hybrid receptors than on vertebrate homomeric (alpha7) or heteromeric (alpha4beta2) nicotinic AChRs. Block by NTX of the chicken alpha7, chicken alpha4beta2 and the SAD/beta2 and ALS/beta2 Drosophila/chicken hybrid receptors is in all cases non-competitive. Thus, the site of action on nicotinic AChRs of NTX, to which the insecticide Cartap is metabolised in insects, differs from that of the major nicotinic AChR-active insecticide, imidacloprid.

  3. 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...

  4. Voltage- and temperature-dependent allosteric modulation of alpha7 nicotinic receptors by PNU120596

    Directory of Open Access Journals (Sweden)

    Fabrio eSitzia

    2011-12-01

    Full Text Available Alpha7 nicotinic receptors (a7nAChR are widely distributed throughout the central nervous system (CNS and are found at particularly high levels in the hippocampus and cortex. Several lines of evidence indicate that pharmacological enhancement of a7nAChRs function could be a potential therapeutic route to alleviate disease-related cognitive deficits. A recent pharmacological approach adopted to increase a7nAChR activity has been to identify selective positive allosteric modulators (PAMs. a7nAChR PAMs have been divided into two classes: type I PAMs increase agonist potency with only subtle effects on kinetics, whereas type II agents produce additional dramatic effects on desensitization and deactivation kinetics. Here we report novel observations concerning the pharmacology of the canonical type II PAM, PNU120596. Using patch clamp analysis of acetylcholine (ACh-mediated currents through recombinant rat a7nAChR we show that positive allosteric modulation measured in two different ways is greatly attenuated when the temperature is raised to near physiological levels. Furthermore, PNU120596 largely removes the strong inward rectification usually exhibited by a7nAChR-mediated responses.

  5. Circulating antibodies against nicotinic acetylcholine receptors in chagasic patients

    Science.gov (United States)

    GOIN, J C; VENERA, G; BONINO, M BISCOGLIO DE JIMÉNEZ; STERIN-BORDA, L

    1997-01-01

    Human and experimental Chagas' disease causes peripheral nervous system damage involving neuromuscular transmission alterations at the neuromuscular junction. Additionally, autoantibodies directed to peripheral nerves and sarcolemmal proteins of skeletal muscle have been described. In this work, we analyse the ability of serum immunoglobulin factors associated with human chagasic infection to bind the affinity-purified nicotinic acetylcholine receptor (nAChR) from electric organs of Discopyge tschudii and to identify the receptor subunits involved in the interaction. The frequency of serum anti-nAChR reactivity assayed by dot-blot was higher in seropositive chagasic patients than in uninfected subjects. Purified IgG obtained from chagasic patients immunoprecipitated a significantly higher fraction of the solubilized nAChR than normal IgG. Furthermore, immunoblotting assays indicated that α and β are the main subunits involved in the interaction. Chagasic IgG was able to inhibit the binding of α-bungarotoxin to the receptor in a concentration-dependent manner, confirming the contribution of the α-subunit in the autoantibody-receptor interaction. The presence of anti-nAChR antibodies was detected in 73% of chagasic patients with impairment of neuromuscular transmission in conventional electromyographical studies, indicating a strong association between seropositive reactivity against nAChR and electromyographical abnormalities in chagasic patients. The chronic binding of these autoantibodies to the nAChR could induce a decrease in the population of functional nAChRs at the neuromuscular junction and consequently contribute to the electrophysiological neuromuscular alterations described in the course of chronic Chagas' disease. PMID:9367405

  6. Visualization of cholinoceptive neurons in the rat neocortex : colocalization of muscarinic and nicotinic acetylcholine receptors

    NARCIS (Netherlands)

    Zee, E.A. van der; Streefland, C.; Strosberg, A.D.; Schröder, H.; Luiten, P.G.M.

    1992-01-01

    The present investigation analyzes the cellular distribution of muscarinic and nicotinic acetylcholine receptors in rat neocortex, by use of monoclonal antibodies raised against purified receptor proteins. The degree of colocalization of both types of receptors was determined by way of immunofluores

  7. The effects of nicotine, varenicline, and cytisine on schedule-controlled responding in mice: differences in α4β2 nicotinic receptor activation.

    Science.gov (United States)

    Cunningham, Colin S; McMahon, Lance R

    2011-03-01

    Nicotine, varenicline, and cytisine are pharmacotherapies for tobacco dependence; the extent to which their in vivo effects vary as a function of differences in nicotinic acetylcholine receptor agonism is not clear. Male C57BL/6J mice responding under a fixed ratio 30 schedule of food delivery were used to establish the potency and time course of nicotine, varenicline, and cytisine; antagonism was examined with the non-competitive, non-selective antagonist mecamylamine and the competitive, α4β2 nicotinic receptor antagonist dihydro-β-erythroidine (DHβE). Intraperitoneal nicotine, varenicline, and cytisine dose-dependently decreased responding; nicotine was more potent (ED(50) value=0.83 mg/kg) than varenicline (ED(50) value=2.51 mg/kg) and cytisine (ED(50) value=2.97 mg/kg). The agonists had a similar time course including a rapid onset (5 min or less) and relatively short duration of action (30 min). Mecamylamine dose-dependently attenuated the rate-decreasing effects of a fixed dose of nicotine (1.78 mg/kg), varenicline (5.6 mg/kg), and cytisine (5.6 mg/kg). Mecamylamine (1mg/kg) produced parallel rightward shifts in the dose-response curves for nicotine (3.3-fold), varenicline (3.1-fold), and cytisine (2.3-fold). In contrast, DHβE (3.2mg/kg) produced 2-fold antagonism of nicotine and did not antagonize varenicline or cytisine. The data strongly suggest that nicotinic acetylcholine receptors mediate the effects of the agonists to decrease operant responding in mice. However, α4β2 receptor agonism appears to contribute partially to the rate-decreasing effects of nicotine but not to the rate-decreasing effects of varenicline and cytisine. Differential activation of α4β2 receptors in vivo might contribute to differences in the effectiveness of these smoking cessation aids.

  8. 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.

  9. Prenatal Exposure to Nicotine and Childhood Asthma: Role of Nicotine Acetylcholine Receptors, Neuropeptides and Fibronectin Expression in Lung

    Science.gov (United States)

    2008-12-01

    original articles and 1 review article . 15. SUBJECT TERMS asthma, lung development, matrix, receptors 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...and Roman J. Exp Lung Research, 34:481-499, 2008). A review article describing this and other work related to tobacco-related lung disease and how...and Roman J. Tobacco smoke exposure, nicotine, and the embryologic origins of asthma. Current Respiratory Reviews, 2009, in press.

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

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    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.

  11. 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 BACKGROUND: 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. RESULTS: 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. CONCLUSIONS: 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.

  12. Early Life Stress, Nicotinic Acetylcholine Receptors and Alcohol Use Disorders

    Directory of Open Access Journals (Sweden)

    Joan Y. Holgate

    2015-06-01

    Full Text Available Stress is a major driving force in alcohol use disorders (AUDs. It influences how much one consumes, craving intensity and whether an abstinent individual will return to harmful alcohol consumption. We are most vulnerable to the effects of stress during early development, and exposure to multiple traumatic early life events dramatically increases the risk for AUDs. However, not everyone exposed to early life stress will develop an AUD. The mechanisms determining whether an individual’s brain adapts and becomes resilient to the effects of stress or succumbs and is unable to cope with stress remain elusive. Emerging evidence suggests that neuroplastic changes in the nucleus accumbens (NAc following early life stress underlie the development of AUDs. This review discusses the impact of early life stress on NAc structure and function, how these changes affect cholinergic signaling within the mesolimbic reward pathway and the role nicotinic acetylcholine receptors (nAChRs play in this process. Understanding the neural pathways and mechanism determining stress resilience or susceptibility will improve our ability to identify individuals susceptible to developing AUDs, formulate cognitive interventions to prevent AUDs in susceptible individuals and to elucidate and enhance potential therapeutic targets, such as the nAChRs, for those struggling to overcome an AUD.

  13. Brain Imaging of Nicotinic Receptors in Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Jin Wu

    2010-01-01

    Full Text Available Neuronal nicotinic acetylcholine receptors (nAChRs are a family of ligand-gated ion channels which are widely distributed in the human brain. Several lines of evidence suggest that two major subtypes (α4β2 and α7 of nAChRs play an important role in the pathophysiology of Alzheimer's disease (AD. Postmortem studies demonstrated alterations in the density of these subtypes of nAChRs in the brain of patients with AD. Currently, nAChRs are one of the most attractive therapeutic targets for AD. Therefore, several researchers have made an effort to develop novel radioligands that can be used to study quantitatively the distribution of these two subtypes in the human brain with positron emission tomography (PET and single-photon emission computed tomography (SPECT. In this paper, we discuss the current topics on in vivo imaging of two subtypes of nAChRs in the brain of patients with AD.

  14. Cycloxaprid insecticide: nicotinic acetylcholine receptor binding site and metabolism.

    Science.gov (United States)

    Shao, Xusheng; Swenson, Tami L; Casida, John E

    2013-08-21

    Cycloxaprid (CYC) is a novel neonicotinoid prepared from the (nitromethylene)imidazole (NMI) analogue of imidacloprid. In this study we consider whether CYC is active per se or only as a proinsecticide for NMI. The IC50 values (nM) for displacing [(3)H]NMI binding are 43-49 for CYC and 2.3-3.2 for NMI in house fly and honeybee head membranes and 302 and 7.2, respectively, in mouse brain membranes, potency relationships interpreted as partial conversion of some CYC to NMI under the assay conditions. The 6-8-fold difference in toxicity of injected CYC and NMI to house flies is consistent with their relative potencies as in vivo nicotinic acetylcholine receptor (nAChR) inhibitors in brain measured with [(3)H]NMI binding assays. CYC metabolism in mice largely involves cytochrome P450 pathways without NMI as a major intermediate. Metabolites of CYC tentatively assigned are five monohydroxy derivatives and one each of dihydroxy, nitroso, and amino modifications. CYC appears be a proinsecticide, serving as a slow-release reservoir for NMI with selective activity for insect versus mammalian nAChRs.

  15. Alpha-conotoxins as pharmacological probes of nicotinic acetylcholine receptors

    Institute of Scientific and Technical Information of China (English)

    Layla AZAM; J Michael MCINTOSH

    2009-01-01

    Cysteine-rich peptides from the venom of cone snails (Conus) target a wide variety of different ion channels. One family of conopeptides, the a-conotoxins, specifically target different isoforms of nicotinic acetylcholine receptors (nAChRs) found both in the neuromuscular junction and central nervous system. This family is further divided into subfamilies based on the number of amino acids between cysteine residues. The exquisite subtype selectivity of certain a-conotoxins has been key to the characterization of native nAChR isoforms involved in modulation of neurotransmitter release, the pathophysiol-ogy of Parkinson's disease and nociception. Structure/function characterization of a-conotoxins has led to the development of analogs with improved potency and/or subtype selectivity. Cyclization of the backbone structure and addition of lipo-philic moieties has led to improved stability and bioavailability of a-conotoxins, thus paving the way for orally available therapeutics. The recent advances in phylogeny, exogenomics and molecular modeling promises the discovery of an even greater number of a-conotoxins and analogs with improved selectivity for specific subtypes of nAChRs.

  16. Nicotinic acetylcholine receptor agonist attenuates ILC2-dependent airway hyperreactivity

    Science.gov (United States)

    Galle-Treger, Lauriane; Suzuki, Yuzo; Patel, Nisheel; Sankaranarayanan, Ishwarya; Aron, Jennifer L.; Maazi, Hadi; Chen, Lin; Akbari, Omid

    2016-01-01

    Allergic asthma is a complex and chronic inflammatory disorder that is associated with airway hyperreactivity (AHR) and driven by Th2 cytokine secretion. Type 2 innate lymphoid cells (ILC2s) produce large amounts of Th2 cytokines and contribute to the development of AHR. Here, we show that ILC2s express the α7-nicotinic acetylcholine receptor (α7nAChR), which is thought to have an anti-inflammatory role in several inflammatory diseases. We show that engagement of a specific agonist with α7nAChR on ILC2s reduces ILC2 effector function and represses ILC2-dependent AHR, while decreasing expression of ILC2 key transcription factor GATA-3 and critical inflammatory modulator NF-κB, and reducing phosphorylation of upstream kinase IKKα/β. Additionally, the specific α7nAChR agonist reduces cytokine production and AHR in a humanized ILC2 mouse model. Collectively, our data suggest that α7nAChR expressed by ILC2s is a potential therapeutic target for the treatment of ILC2-mediated asthma. PMID:27752043

  17. Actions of piperidine alkaloid teratogens at fetal nicotinic acetylcholine receptors.

    Science.gov (United States)

    Green, Benedict T; Lee, Stephen T; Panter, Kip E; Welch, Kevin D; Cook, Daniel; Pfister, James A; Kem, William R

    2010-01-01

    Teratogenic alkaloids are found in many species of plants including Conium maculatum L., Nicotiana glauca, Nicotiana tabaccum, and multiple Lupinus spp. Fetal musculoskeletal defects produced by alkaloids from these plants include arthrogyropisis, scoliosis, torticollis, kyposis, lordosis, and cleft palate. A pharmacodynamic comparison of the alkaloids ammodendrine, anabasine, anabaseine, anagyrine, and coniine in SH-SY5Y cells and TE-671 cells was made. These alkaloids and their enantiomers were more effective in depolarizing TE-671 cells which express the human fetal-muscle type nicotinic acetylcholine receptor (nAChR) relative to SH-SY5Y cells which predominately express autonomic nAChRs. The rank order of potency in TE-671 cells was: anabaseine>(+)-anabasine>(-)-anabasine > (+/-)-anabasine>anagyrine>(-)-coniine > (+/-)-coniine>(+)-coniine>(+/-)-ammodendrine>(+)-ammodendrine. The rank order potency in SH-SY5Y cells was: anabaseine>(+)-anabasine>(-)-coniine>(+)-coniine>(+)-ammodendrine>anagyrine>(-)-anabasine>(+/-)-coniine>(+/-)-anabasine>(-)-ammodendrine. The actions of these alkaloids at nAChRs in both cell lines could be distinguished by their maximum effects in depolarizing cell membrane potential. The teratogenic action of these compounds may be related to their ability to activate and subsequently desensitize nAChRs.

  18. Estradiol pretreatment attenuated nicotine-induced endothelial cell apoptosis via estradiol functional membrane receptor.

    Science.gov (United States)

    Wang, Li-li; Zhao, Jian-li; Lau, Wayne-Bond; Zhang, Yan-qing; Qiao, Zhong-dong; Wang, Ya-jing

    2011-06-01

    Cigarette smoking is highly associated with increased cardiovascular disease complications. The female population, however, manifests reduced cardiovascular morbidity. We define nicotine's effect upon human umbilical vein endothelial cells (HUVECs), determine whether estradiol might ameliorate endothelial dysfunction via its membrane estrogen receptor (mER), and attempt to elucidate the underlying mechanisms. Endothelial cells were pretreated with estradiol-BSA and measured resultant ion flux across the cells via the patch clamp technique to assess mER is functionality. Estradiol-BSA administration was associated with 30% decreased nicotine-induced apoptosis and also attenuated nicotine-activated phosphorylation of p38 and ERK. Pretreatment of estradiol-BSA triggered a low calcium influx, suggesting ahead low influx calcium played a critical role in the underlying protective mechanisms of estradiol. Furthermore, this estradiol-BSA protection against apoptosis remained effective in the presence of tamoxifen, an intracellular estrogen receptor (iER) inhibitor. Additionally, tamoxifen did not abolish estradiol-BSA's inhibitory effect upon p38 and ERK's activation, giving evidence to the obligatory role of p38 and ERK signaling in the estradiol-BSA's anti-apoptotic action via mER. Our study provides evidence that nicotine enhances endothelial cell apoptosis, but estrogen exerts anti-apoptotic effect through its functional membrane estrogen receptor. Clinically, the nicotine in cigarettes might contribute to endothelial dysfunction, whereas ambient estradiol may provide cellular protection against nicotine-induced injury through its functional membrane receptor via MAPK pathway downregulation.

  19. Opioid receptor types involved in the development of nicotine physical dependence in an invertebrate (Planaria) model.

    Science.gov (United States)

    Raffa, Robert B; Baron, Steve; Bhandal, Jaspreet S; Brown, Tevin; Song, Kevin; Tallarida, Christopher S; Rawls, Scott M

    2013-11-01

    Recent data suggest that opioid receptors are involved in the development of nicotine physical dependence in mammals. Evidence in support of a similar involvement in an invertebrate (Planaria) is presented using the selective opioid receptor antagonist naloxone, and the more receptor subtype-selective antagonists CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2) (μ, MOR), naltrindole (δ, DOR), and nor-BNI (norbinaltorphimine) (κ, KOR). Induction of physical dependence was achieved by 60-min pre-exposure of planarians to nicotine and was quantified by abstinence-induced withdrawal (reduction in spontaneous locomotor activity). Known MOR and DOR subtype-selective opioid receptor antagonists attenuated the withdrawal, as did the non-selective antagonist naloxone, but a KOR subtype-selective antagonist did not. An involvement of MOR and DOR, but not KOR, in the development of nicotine physical dependence or in abstinence-induced withdrawal was thus demonstrated in a sensitive and facile invertebrate model.

  20. Conditional knockout of NMDA receptors in dopamine neurons prevents nicotine-conditioned place preference.

    Directory of Open Access Journals (Sweden)

    Lei Phillip Wang

    Full Text Available 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.

  1. Nicotinic excitatory postsynaptic potentials in hippocampal CA1 interneurons are predominantly mediated by nicotinic receptors that contain α4 and β2 subunits.

    Science.gov (United States)

    Bell, Karen A; Shim, Hoon; Chen, Ching-Kang; McQuiston, A Rory

    2011-12-01

    In the hippocampus, activation of nicotinic receptors that include α4 and β2 subunits (α4β2*) facilitates memory formation. α4β2* receptors may also play a role in nicotine withdrawal, and their loss may contribute to cognitive decline in aging and Alzheimer's disease (AD). However, little is known about their cellular function in the hippocampus. Therefore, using optogenetics, whole cell patch clamping and voltage-sensitive dye (VSD) imaging, we measured nicotinic excitatory postsynaptic potentials (EPSPs) in hippocampal CA1. In a subpopulation of inhibitory interneurons, release of ACh resulted in slow depolarizations (rise time constant 33.2 ± 6.5 ms, decay time constant 138.6 ± 27.2 ms) mediated by the activation of α4β2* nicotinic receptors. These interneurons had somata and dendrites located in the stratum oriens (SO) and stratum lacunosum-moleculare (SLM). Furthermore, α4β2* nicotinic EPSPs were largest in the SLM. Thus, our data suggest that nicotinic EPSPs in hippocampal CA1 interneurons are predominantly mediated by α4β2* nicotinic receptors and their activation may preferentially affect extrahippocampal inputs in SLM of hippocampal CA1.

  2. Nicotine attenuates activation of tissue resident macrophages in the mouse stomach through the β2 nicotinic acetylcholine receptor.

    Directory of Open Access Journals (Sweden)

    Andrea Nemethova

    Full Text Available BACKGROUND: The cholinergic anti-inflammatory pathway is an endogenous mechanism by which the autonomic nervous system attenuates macrophage activation via nicotinic acetylcholine receptors (nAChR. This concept has however not been demonstrated at a cellular level in intact tissue. To this end, we have studied the effect of nicotine on the activation of resident macrophages in a mouse stomach preparation by means of calcium imaging. METHODS: Calcium transients ([Ca(2+]i in resident macrophages were recorded in a mouse stomach preparation containing myenteric plexus and muscle layers by Fluo-4. Activation of macrophages was achieved by focal puff administration of ATP. The effects of nicotine on activation of macrophages were evaluated and the nAChR involved was pharmacologically characterized. The proximity of cholinergic nerves to macrophages was quantified by confocal microscopy. Expression of β2 and α7 nAChR was evaluated by β2 immunohistochemistry and fluorophore-tagged α-bungarotoxin. RESULTS: In 83% of macrophages cholinergic varicose nerve fibers were detected at distances <900 nm. The ATP induced [Ca(2+]i increase was significantly inhibited in 65% or 55% of macrophages by 100 µM or 10 µM nicotine, respectively. This inhibitory effect was reversed by the β2 nAChR preferring antagonist dihydro-β-eryhtroidine but not by hexamethonium (non-selective nAChR-antagonist, mecamylamine (α3β4 nAChR-preferring antagonist, α-bungarotoxin or methyllycaconitine (both α7 nAChR-preferring antagonist. Macrophages in the stomach express β2 but not α7 nAChR at protein level, while those in the intestine express both receptor subunits. CONCLUSION: This study is the first in situ demonstration of an inhibition of macrophage activation by nicotine suggesting functional signaling between cholinergic neurons and macrophages in the stomach. The data suggest that the β2 subunit of the nAChR is critically involved in the nicotine-induced inhibition

  3. Block of nicotinic acetylcholine receptors by philanthotoxins is strongly dependent on their subunit composition

    DEFF Research Database (Denmark)

    Kachel, Hamid S; Patel, Rohit N; Franzyk, Henrik

    2016-01-01

    -fold selectivity of PhTX-12 over PhTX-343 for embryonic muscle-type nicotinic acetylcholine receptors (nAChRs) in TE671 cells. We investigated their inhibition of different neuronal nAChR subunit combinations as well as of embryonic muscle receptors expressed in Xenopus oocytes. Whole-cell currents...

  4. Nicotine Withdrawal-Induced Deficits in Trace Fear Conditioning in C57BL/6 Mice: A Role for High-Affinity β2 Subunit-Containing Nicotinic Acetylcholine Receptors

    OpenAIRE

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

    2009-01-01

    Nicotine alters cognitive processes that include working memory and long-term memory. Trace fear conditioning may involve working memory during acquisition while also allowing the assessment of long-term memory. The present study used trace fear conditioning in C57BL/6 mice to investigate the effects of acute nicotine, chronic nicotine, and withdrawal of chronic nicotine on processes active during acquisition and recall 24 hours later and examine the nicotinic acetylcholine receptor subtypes ...

  5. Spectral confocal imaging of fluorescently tagged nicotinic receptors in knock-in mice with chronic nicotine administration.

    Science.gov (United States)

    Renda, Anthony; Nashmi, Raad

    2012-02-10

    Ligand-gated ion channels in the central nervous system (CNS) are implicated in numerous conditions with serious medical and social consequences. For instance, addiction to nicotine via tobacco smoking is a leading cause of premature death worldwide (World Health Organization) and is likely caused by an alteration of ion channel distribution in the brain. Chronic nicotine exposure in both rodents and humans results in increased numbers of nicotinic acetylcholine receptors (nAChRs) in brain tissue. Similarly, alterations in the glutamatergic GluN1 or GluA1 channels have been implicated in triggering sensitization to other addictive drugs such as cocaine, amphetamines and opiates. Consequently, the ability to map and quantify distribution and expression patterns of specific ion channels is critically important to understanding the mechanisms of addiction. The study of brain region-specific effects of individual drugs was advanced by the advent of techniques such as radioactive ligands. However, the low spatial resolution of radioactive ligand binding prevents the ability to quantify ligand-gated ion channels in specific subtypes of neurons. Genetically encoded fluorescent reporters, such as green fluorescent protein (GFP) and its many color variants, have revolutionized the field of biology. By genetically tagging a fluorescent reporter to an endogenous protein one can visualize proteins in vivo. One advantage of fluorescently tagging proteins with a probe is the elimination of antibody use, which have issues of nonspecificity and accessibility to the target protein. We have used this strategy to fluorescently label nAChRs, which enabled the study of receptor assembly using Förster Resonance Energy Transfer (FRET) in transfected cultured cells. More recently, we have used the knock-in approach to engineer mice with yellow fluorescent protein tagged α4 nAChR subunits (α4YFP), enabling precise quantification of the receptor ex vivo at submicrometer resolution in CNS

  6. Cellular approaches to the interaction between cannabinoid receptor ligands and nicotinic acetylcholine receptors.

    Science.gov (United States)

    Oz, Murat; Al Kury, Lina; Keun-Hang, Susan Yang; Mahgoub, Mohamed; Galadari, Sehamuddin

    2014-05-15

    Cannabinoids are among the earliest known drugs to humanity. Cannabis plant contains various phytochemicals that bind to cannabinoid receptors. In addition, synthetic and endogenously produced cannabinoids (endocannabinoids) constitute other classes of cannabinoid receptor ligands. Although many pharmacological effects of these cannabinoids are mediated by the activation of cannabinoid receptors, recent studies indicate that cannabinoids also modulate the functions of various integral membrane proteins including ion channels, receptors, neurotransmitter transporters, and enzymes by mechanism(s) not involving the activation of known cannabinoid receptors. Currently, the mechanisms of these effects were not fully understood. However, it is likely that direct actions of cannabinoids are closely linked to their lipophilic structures. This report will focus on the actions of cannabinoids on nicotinic acetylcholine receptors and will examine the results of recent studies in this field. In addition some mechanistic approaches will be provided. The results discussed in this review indicate that, besides cannabinoid receptors, further molecular targets for cannabinoids exist and that these targets may represent important novel sites to alter neuronal excitability.

  7. From Smoking to Cancers: Novel Targets to Neuronal Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Chia-Hwa Lee

    2011-01-01

    Full Text Available Cigarette smoking bears a strong etiological association with many neovascularization-related diseases, including cancer, cardiovascular disease, and age-related macular degeneration. Cigarette smoke is a complex mixture of many compounds, including nicotine, which is the major active and addictive component of tobacco. Nicotine and its specific metabolized carcinogens directly bind to nicotinic acetylcholine receptors (nAChRs on cell membranes and trigger the nAChR signal cascade. The nAChRs were originally thought to be ligand-gated ion channels that modulate physiological processes ranging from neurotransmission to cancer signaling. For several decades, the nAChRs served as a prototypic molecule for neurotransmitter receptors; however, they are now important therapeutic targets for various diseases, including Alzheimer's and Parkinson's diseases, schizophrenia, and even cancer. This paper describes recent advances in our understanding of the assembly, activity, and biological functions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands.

  8. Functional distribution of nicotinic receptors in CA3 region of the hippocampus.

    Science.gov (United States)

    Grybko, Michael; Sharma, Geeta; Vijayaraghavan, Sukumar

    2010-01-01

    Nicotinic acetylcholine receptor (nAChR) modulation of a number of parameters of synaptic signaling in the brain has been demonstrated. It is likely that effects of nicotine are due to its ability to modulate network excitability as a whole. A pre-requisite to understanding the effects of nicotine on network properties is the elucidation of functional receptors. We have examined the distribution of functional nAChRs in the dentate gyrus granule cells and the CA3 region of the mammalian hippocampus using calcium imaging from acute slices. Our results demonstrate the presence of functional nAChRs containing the alpha7 subunit (alpha7-nAChRs) on mossy fiber boutons, CA3 pyramidal cells, and on astrocytes. In addition, both CA3 interneurons and granule cells show nicotinic signals. Our study suggests that functional nicotinic receptors are widespread in their distribution and that calcium imaging might be an effective technique to examine locations of these receptors in the mammalian brain.

  9. 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.

  10. Basolateral amygdala CB1 cannabinoid receptors mediate nicotine-induced place preference.

    Science.gov (United States)

    Hashemizadeh, Shiva; Sardari, Maryam; Rezayof, Ameneh

    2014-06-03

    In the present study, the effects of bilateral microinjections of cannabinoid CB1 receptor agonist and antagonist into the basolateral amygdala (intra-BLA) on nicotine-induced place preference were examined in rats. A conditioned place preference (CPP) apparatus was used for the assessment of rewarding effects of the drugs in adult male Wistar rats. Subcutaneous (s.c.) administration of nicotine (0.2mg/kg) induced a significant CPP, without any effect on the locomotor activity during the testing phase. Intra-BLA microinjection of a non-selective cannabinoid CB1/CB2 receptor agonist, WIN 55,212-2 (0.1-0.5 μg/rat) with an ineffective dose of nicotine (0.1mg/kg, s.c.) induced a significant place preference. On the other hand, intra-BLA administration of AM251 (20-60 ng/rat), a selective cannabinoid CB1 receptor antagonist inhibited the acquisition of nicotine-induced place preference. It should be considered that the microinjection of the same doses of WIN 55,212-2 or AM251 into the BLA, by itself had no effect on the CPP score. The administration of a higher dose of AM251 (60 ng/rat) during the acquisition decreased the locomotor activity of animals on the testing phase. Interestingly, the microinjection of AM251 (20 and 40 ng/rat), but not WIN55,212-2 (0.1-0.5 μg/rat), into the BLA inhibited the expression of nicotine-induced place preference without any effect on the locomotor activity. Taken together, these findings support the possible role of endogenous cannabinoid system of the BLA in the acquisition and the expression of nicotine-induced place preference. Furthermore, it seems that there is a functional interaction between the BLA cannabinoid receptors and nicotine in producing the rewarding effects.

  11. 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.

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

    Science.gov (United States)

    Ring, Avi; Strom, Bjorn Oddvar; Turner, Simon R; Timperley, Christopher M; Bird, Michael; Green, A Christopher; Chad, John E; Worek, Franz; Tattersall, John E H

    2015-01-01

    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.

  13. Allosteric modulation of alpha4beta2 nicotinic acetylcholine receptors by HEPES.

    Science.gov (United States)

    Weltzin, Maegan M; Huang, Yanzhou; Schulte, Marvin K

    2014-06-05

    A number of new positive allosteric modulators (PAMs) have been reported that enhance responses of neuronal alpha7 and alpha4beta2 nicotinic acetylcholine receptor subtypes to orthosteric ligands. PAMs represent promising new leads for the development of therapeutic agents for disorders involving alterations in nicotinic neurotransmission including Autism, Alzheimer's and Parkinson's disease. During our recent studies of alpha4beta2 PAMs, we identified a novel effect of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES). The effects of HEPES were evaluated in a phosphate buffered recording solution using two-electrode voltage clamp techniques and alpha4beta2 and alpha7 nicotinic acetylcholine receptor subtypes expressed in Xenopus laevis oocytes. Acetylcholine induced responses of high-sensitivity alpha4beta2 receptors were potentiated 190% by co-exposure to HEPES. Responses were inhibited at higher concentrations (bell-shaped concentration/response curve). Coincidentally, at concentrations of HEPES typically used in oocyte recording (5-10mM), the potentiating effects of HEPES are matched by its inhibitory effects, thus producing no net effect. Mutagenesis results suggest HEPES potentiates the high-sensitivity stoichiometry of the alpha4beta2 receptors through action at the beta2+/beta2- interface and is dependent on residue beta2D218. HEPES did not potentiate low-sensitivity alpha4beta2 receptors and did not produce any observable effect on acetylcholine induced responses on alpha7 nicotinic acetylcholine receptors.

  14. 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.

  15. A critical role for the melanocortin 4 receptor in stress-induced relapse to nicotine seeking in rats.

    Science.gov (United States)

    Qi, Xiaoli; Yamada, Hidetaka; Corrie, Lu W; Ji, Yue; Bauzo, Rayna M; Alexander, Jon C; Bruijnzeel, Adrie W

    2015-03-01

    Tobacco addiction is characterized by a lack of control over smoking and relapse after periods of abstinence. Smoking cessation leads to a dysphoric state that contributes to relapse to smoking. After the acute withdrawal phase, exposure to stressors increases the risk for relapse. Blockade of melanocortin 4 (MC4 ) receptors has anxiolytic and antidepressant-like effects in animal models. The aim of these studies was to investigate the role of MC4 receptors in the dysphoria associated with nicotine withdrawal and stress-induced reinstatement of nicotine seeking. To study stress-induced reinstatement, rats self-administered nicotine for 16 days and then nicotine seeking was extinguished by substituting saline for nicotine. Nicotine seeking was reinstated by intermittent footshock stress. The intracranial self-stimulation (ICSS) procedure was used to assess the negative mood state associated with nicotine withdrawal. Elevations in the ICSS thresholds are indicative of a dysphoric state. The selective MC4 receptor antagonists HS014 and HS024 prevented stress-induced reinstatement of extinguished nicotine seeking. Drug doses that prevented stress-induced relapse did not affect responding for food pellets, which indicates that the drugs did not induce sedation or motor impairments. In the ICSS experiments, the nicotinic acetylcholine receptor antagonist mecamylamine elevated the ICSS thresholds of the nicotine-dependent rats. Pre-treatment with HS014 or HS024 did not prevent the elevations in ICSS thresholds. These studies indicate that MC4 receptors play a critical role in stress-induced reinstatement of nicotine seeking, but these receptors may not play a role in the dysphoria associated with acute nicotine withdrawal.

  16. Nicotine analogues as potential therapeutic agents in Parkinson’s disease by targeting nicotinic acetylcholine receptors (nAChRs in astrocytes

    Directory of Open Access Journals (Sweden)

    Valentina Echeverria Moran

    2015-02-01

    Full Text Available Parkinson’s disease (PD is a relatively common disorder of the Central Nervous System (CNS, whose etiology is characterized by a selective and progressive degeneration of dopaminergic neurons, and the presence of Lewy bodies in the pars compacta of the substantia nigra, thus dopamine depletion in the striatum. Patients with this disease suffer from tremors, slowness of movements, gait instability, rigidity, and may also present functional disability, reduced quality of life, and rapid cognitive decline. The prevalence of this disease is in a range of 107-187 per 100,000 inhabitants. Previous studies have shown that nicotine exerts beneficial effects in patients with PD and in in vitro and in vivo models of this disease. Astrocytes have an important role in the immune system, and that nicotine might be able to reduce inflammation-induced activation of pro-apoptotic signaling in PD. Nicotine might exert its effect through activation of α7 nicotinic acetylcholine receptors (α7-nAChRs expressed in glial cells. Moreover, nicotine administration can protect dopaminergic neurons against degeneration by inhibiting astrocytes activation in the substantia nigra pars compacta (SNpc and therefore reducing inflammation. Besides this beneficial effect of nicotine, its continuing use can induce toxicity and cause dependency. To counteract this effect, nicotine analogues have risen as an important therapeutic approach to maintain nicotine´s beneficial effects, but avoid its toxicity. Since astrocytes might drive chronic inflammatory processes in PD, therefore increasing neuronal vulnerability to damage, the administration of nicotine analogues in astrocytes is of interest to diminish neuronal death. In this work, we assess the role of different nicotine analogues in astrocytes following rotenone stimuli, and determine whether the possible beneficial effects of nicotine are via activation of α7-nAChRs.

  17. The kappa-opioid receptor is involved in the stimulating effect of nicotine on adrenocortical activity but not in nicotine induced anxiety.

    Science.gov (United States)

    Marco, Eva Maria; Llorente, Ricardo; Pérez-Alvarez, Laura; Moreno, Enrique; Guaza, Carmen; Viveros, Maria Paz

    2005-09-01

    The kappa (kappa) opioid system appears to interact with nicotine in the modulation of locomotion and addiction related processes. In this study we have investigated the possible implication of the kappa-opioid system in the effects of nicotine on anxiety and adrenocortical activity. In two different experiments, we analysed the possible interaction between nicotine (0.5 mg/kg i.p.) and either the kappa-opioid receptor antagonist nor-binaltorphimine (5 mg/kg i.p.) or the kappa-opioid receptor agonist U50,488H (1 mg/kg s.c.). Behavioural and endocrine experiments were performed in different groups of animals. Animals were exposed to the holeboard immediately followed by the plus-maze. Serum corticosterone levels were determined by radioimmunoassay. Nicotine induced an anxiogenic-like effect in the plus-maze and a significant decrease of holeboard activity. The anxiogenic-like effect in the plus-maze was not modified by any of the kappa-opioid receptor ligands. Nicotine also induced a significant increase in the corticosterone levels, and the kappa antagonist, which did not exert any effect per se, antagonised this effect. The kappa-agonist U50,488H induced a significant increase in corticosterone concentration when administered alone. We provide the first evidence for the involvement of the kappa-opioid receptor in the stimulatory effect of nicotine on adrenocortical activity.

  18. Nicotinic receptor mediates nitric oxide synthase expression in the rat gastric myenteric plexus.

    Science.gov (United States)

    Nakamura, K; Takahashi, T; Taniuchi, M; Hsu, C X; Owyang, C

    1998-04-01

    The mechanism that regulates the synthesis of nitric oxide synthase (NOS), a key enzyme responsible for NO production in the myenteric plexus, remains unknown. We investigated the roles of the vagal nerve and nicotinic synapses in the mediation of NOS synthesis in the gastric myenteric plexus in rats. Truncal vagotomy and administration of hexamethonium significantly reduced nonadrenergic, noncholinergic relaxation, the catalytic activity of NOS, the number of NOS-immunoreactive cells, and the density of NOS-immunoreactive bands and NOS mRNA bands obtained from gastric tissue. These results suggest that NOS expression in the gastric myenteric plexus is controlled by the vagal nerve and nicotinic synapses. We also investigated if stimulation of the nicotinic receptor increases neuronal NOS (nNOS) expression in cultured gastric myenteric ganglia. Incubation of cultured gastric myenteric ganglia with the nicotinic receptor agonist, 1,1-dimethyl-4-phenylpiperizinium (DMPP, 10(-10)-10(-7) M), for 24 h significantly increased the number of nNOS-immunoreactive cells and the density of immunoreactive nNOS bands and nNOS mRNA bands. nNOS mRNA expression stimulated by DMPP was antagonized by a protein kinase C antagonist, a phospholipase C inhibitor, and an intracellular Ca2+ chelator. We concluded that activation of the nicotinic receptor stimulates a Ca2+-dependent protein kinase C pathway, which in turn, upregulates nNOS mRNA expression and nNOS synthesis in the gastric myenteric plexus.

  19. Synthesis and nicotinic receptor activity of a hydroxylated tropane

    DEFF Research Database (Denmark)

    Bremner, John B; Godfrey, Colette A; Jensen, Anders A.

    2004-01-01

    (+/-)-3alpha-hydroxy homoepibatidine 4 has been synthesized from the alkaloid scopolamine 5 and its properties as a nicotinic agonist assessed. While still binding strongly, the compound showed reduced agonist potency for the alpha(4)beta(2) nAChR compared with the parent compound epibatidine 1....... Compound 4 also displayed generally similar binding and selectivity profiles at alpha(4)beta(2), alpha(2)beta(4), alpha(3)beta(4), and alpha(4)beta(4) nAChR subtypes to those for nicotine....

  20. Cross-regulation between colocalized nicotinic acetylcholine and 5-HT3 serotonin receptors on presynaptic nerve terminals

    Institute of Scientific and Technical Information of China (English)

    John J DOUGHERTY; Robert A NICHOLS

    2009-01-01

    Aim: Substantial colocalization of functionally independent a4 nicotinic acetylcholine receptors and 5-HT3 serotonin receptors on presynaptic terminals has been observed in brain. The present study was aimed at addressing whether nicotinic acetylcholine receptors and 5-HT3 serotonin receptors interact on the same presynaptic terminal, suggesting a convergence of cholinergic and serotonergic regulation.Methods: Ca2+ responses in individual, isolated nerve endings purified from rat striatum were measured using confocal imaging.Results: Application of 500 nmol/L nicotine following sustained stimulation with the highly selective 5-HT3 receptor agonist m-chlorophenylbiguanide at 100 nmol/L resulted in markedly reduced Ca2* responses (28% of control) in only those striatal nerve endings that originally responded to m-chlorophenylbiguanide. The cross-regulation developed over several minutes. Presynaptic nerve endings that had not responded to m-chlorophenylbiguanide, indicating that 5-HT3 receptors were not present, displayed typical responses to nicotine. Application of m-chlorophenylbiguanide following sustained stimulation with nicotine resulted in partially attenuated Ca2* responses (49% of control). Application of m-chlorophenylbiguanide following sustained stimulation with m-chlorophenylbiguanide also resulted in a strong attenuation of Ca2+ responses (12% of control), whereas nicotine-induced Ca2t responses following sustained stimulation with nicotine were not significantly different from control.Conclusion: These results indicate that the presynaptic Ca2+ increases evoked by either 5-HT, receptor or nicotinic acetylcholine receptor activation regulate subsequent responses to 5-HT3 receptor activation, but that only 5-HT3 receptors cross-regulate subsequent nicotinic acetylcholine receptor-mediated responses. The findings suggest a specific interaction between the two receptor systems in the same striatal nerve terminal, likely involving Ca2+-dependent

  1. Novel bis-, tris-, and tetrakis-tertiary amino analogs as antagonists at neuronal nicotinic receptors that mediate nicotine-evoked dopamine release.

    Science.gov (United States)

    Zhang, Zhenfa; Zheng, Guangrong; Pivavarchyk, Marharyta; Deaciuc, A Gabriela; Dwoskin, Linda P; Crooks, Peter A

    2011-01-01

    A series of tertiary amine analogs derived from lead azaaromatic quaternary ammonium salts has been designed and synthesized. The preliminary structure-activity relationships of these new analogs suggest that such tertiary amine analogs, which potently inhibit nicotine-evoked dopamine release from rat striatum, represent drug-like inhibitors of α6-containing nicotinic acetylcholine receptors. The bis-tertiary amine analog 7 exhibited an IC(50) of 0.95 nM, while the tris-tertiary amine analog 19 had an IC(50) of 0.35 nM at nAChRs mediating nicotine-evoked dopamine release.

  2. Selective and regulated trapping of nicotinic receptor weak base ligands and relevance to smoking cessation.

    Science.gov (United States)

    Govind, Anitha P; Vallejo, Yolanda F; Stolz, Jacob R; Yan, Jing-Zhi; Swanson, Geoffrey T; Green, William N

    2017-07-18

    To better understand smoking cessation, we examined the actions of varenicline (Chantix) during long-term nicotine exposure. Varenicline reduced nicotine upregulation of α4β2-type nicotinic receptors (α4β2Rs) in live cells and neurons, but not for membrane preparations. Effects on upregulation depended on intracellular pH homeostasis and were not observed if acidic pH in intracellular compartments was neutralized. Varenicline was trapped as a weak base in acidic compartments and slowly released, blocking (125)I-epibatidine binding and desensitizing α4β2Rs. Epibatidine itself was trapped; (125)I-epibatidine slow release from acidic vesicles was directly measured and required the presence of α4β2Rs. Nicotine exposure increased epibatidine trapping by increasing the numbers of acidic vesicles containing α4β2Rs. We conclude that varenicline as a smoking cessation agent differs from nicotine through trapping in α4β2R-containing acidic vesicles that is selective and nicotine-regulated. Our results provide a new paradigm for how smoking cessation occurs and suggest how more effective smoking cessation reagents can be designed.

  3. Presynaptic α7 nicotinic acetylcholine receptors enhance hippocampal mossy fiber glutamatergic transmission via PKA activation.

    Science.gov (United States)

    Cheng, Qing; Yakel, Jerrel L

    2014-01-01

    Nicotinic acetylcholine receptors (nAChRs) are expressed widely in the CNS, and mediate both synaptic and perisynaptic activities of endogenous cholinergic inputs and pharmacological actions of exogenous compounds (e.g., nicotine and choline). Behavioral studies indicate that nicotine improves such cognitive functions as learning and memory. However, the mechanism of nicotine's action on cognitive function remains elusive. We performed patch-clamp recordings from hippocampal CA3 pyramidal neurons to determine the effect of nicotine on mossy fiber glutamatergic synaptic transmission. We found that nicotine in combination with NS1738, an α7 nAChR-positive allosteric modulator, strongly potentiated the amplitude of evoked EPSCs (eEPSCs), and reduced the EPSC paired-pulse ratio. The action of nicotine and NS1738 was mimicked by PNU-282987 (an α7 nAChR agonist), and was absent in α7 nAChR knock-out mice. These data indicate that activation of α7 nAChRs was both necessary and sufficient to enhance the amplitude of eEPSCs. BAPTA applied postsynaptically failed to block the action of nicotine and NS1738, suggesting again a presynaptic action of the α7 nAChRs. We also observed α7 nAChR-mediated calcium rises at mossy fiber giant terminals, indicating the presence of functional α7 nAChRs at presynaptic terminals. Furthermore, the addition of PNU-282987 enhanced action potential-dependent calcium transient at these terminals. Last, the potentiating effect of PNU-282987 on eEPSCs was abolished by inhibition of protein kinase A (PKA). Our findings indicate that activation of α7 nAChRs at presynaptic sites, via a mechanism involving PKA, plays a critical role in enhancing synaptic efficiency of hippocampal mossy fiber transmission.

  4. Involvement of dorsal hippocampal and medial septal nicotinic receptors in cross state-dependent memory between WIN55, 212-2 and nicotine or ethanol in mice.

    Science.gov (United States)

    Alijanpour, S; Rezayof, A

    2013-08-15

    The present study examined whether nicotinic acetylcholine receptors (nAChRs) of the CA1 regions of the dorsal hippocampus and medial septum (MS) are involved in cross state-dependent memory retrieval between WIN55, 212-2 (WIN, a non-selective CB1/CB2 receptor agonist) and nicotine or ethanol. Memory retrieval was measured in one-trial step-down type passive avoidance apparatus in male adult mice. Pre-training intraperitoneal administration of WIN (0.1-1mg/kg) dose-dependently impaired memory retrieval when it was tested 24h later. Pre-test systemic administration of nicotine (0.6 and 0.7mg/kg, s.c.) or ethanol (0.5g/kg, i.p.) improved WIN-induced memory impairment, suggesting a cross state-dependent memory retrieval between the drugs. Pre-test intra-CA1 microinjection of nicotine (1 and 2μg/mouse) before systemic administration of an ineffective dose of nicotine (0.5mg/kg, s.c.) or ethanol (0.25g/kg) significantly reversed WIN-induced memory impairment. Pre-test intra-CA1 microinjection of mecamylamine (1 and 3μg/mouse) inhibited cross state-dependent memory between WIN and nicotine or ethanol. Moreover, pre-test intra-MS microinjection of nicotine (1 and 2μg/mouse) in combination with systemic administration of a lower dose of nicotine (0.5mg/kg), but not ethanol (0.25g/kg), improved memory impairment induced by pre-training administration of WIN. On the other hand, in the animals that received pre-training WIN and pre-test systemic administration of nicotine (0.7mg/kg), but not ethanol (0.5g/kg), pre-test intra-MS microinjection of mecamylamine (1-5μg/mouse) inhibited WIN-nicotine state-dependent memory retrieval. It should be noted that pre-test intra-CA1 or intra-MS microinjection of nicotine or mecamylamine by itself had no effect on memory retrieval and also could not reverse memory impairment induced by pre-training administration of WIN. It can be concluded that WIN and nicotine or WIN and ethanol can induce state-dependent memory retrieval. In

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

    Science.gov (United States)

    Ito, Satoshi; Gojoubori, Takahiro; Tsunoda, Kou; Yamaguchi, Yoko; Asano, Masatake; Goke, Eiji; Koshi, Ryosuke; Sugano, Naoyuki; Yoshinuma, Naoto; Komiyama, Kazuo; Ito, Koichi

    2013-01-01

    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. 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. Taken together, the results suggested that nicotine might contribute to the development of both cardiovascular and periodontal diseases by inducing the LDLR in OECs thereby disturbing lipid metabolism.

  6. 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

  7. 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...

  8. 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...

  9. Distinct neural pathways mediate alpha7 nicotinic acetylcholine receptor-dependent activation of the forebrain

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hay-Schmidt, Anders; Hansen, Henrik H

    2010-01-01

    alpha(7) nicotinic acetylcholine receptor (nAChR) agonists are candidates for the treatment of cognitive deficits in schizophrenia. Selective alpha(7) nAChR agonists, such as SSR180711, activate neurons in the medial prefrontal cortex (mPFC) and nucleus accumbens shell (ACCshell) in rats, regions...

  10. 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...

  11. Sex Differences in Midbrain Dopamine D2-Type Receptor Availability and Association with Nicotine Dependence.

    Science.gov (United States)

    Okita, Kyoji; Petersen, Nicole; Robertson, Chelsea L; Dean, Andy C; Mandelkern, Mark A; London, Edythe D

    2016-11-01

    Women differ from men in smoking-related behaviors, among them a greater difficulty in quitting smoking. Unlike female smokers, male smokers have lower striatal dopamine D2-type receptor availability (binding potential, BPND) than nonsmokers and exhibit greater smoking-induced striatal dopamine release. Because dopamine D2-type autoreceptors in the midbrain influence striatal dopamine release, a function that has been linked to addiction, we tested for sex differences in midbrain dopamine D2-type receptor BPND and in relationships between midbrain BPND, nicotine dependence and striatal dopamine D2-type receptor BPND. Positron emission tomography was used with [(18)F]fallypride to measure BPND in a midbrain region, encompassing the substantia nigra and ventral tegmental area, in 18 daily smokers (7 women, 11 men) and 19 nonsmokers (10 women, 9 men). A significant sex-by-group interaction reflected greater midbrain BPND in female but not male smokers than in corresponding nonsmokers (F1, 32=5.089, p=0.03). Midbrain BPND was positively correlated with BPND in the caudate nucleus and putamen in nonsmokers and female smokers but not in male smokers and with nicotine dependence in female but not in male smokers. Striatal BPND was correlated negatively with nicotine dependence and smoking exposure. These findings extend observations on dopamine D2-type receptors in smokers and suggest a sex difference in how midbrain dopamine D2-type autoreceptors influence nicotine dependence.

  12. 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...

  13. Cytisine: a natural product lead for the development of drugs acting at nicotinic acetylcholine receptors.

    Science.gov (United States)

    Pérez, Edwin G; Méndez-Gálvez, Carolina; Cassels, Bruce K

    2012-05-01

    Covering: up to the end of 2011. This review covers classical and modern structural modifications of the alkaloid, the more recent (since 2007) syntheses of cytisine and analogues, and the pharmacology of these compounds, with emphasis on their interactions with nicotinic receptors. 89 references are cited.

  14. Vagus Nerve Activity Augments Intestinal Macrophage Phagocytosis via Nicotinic Acetylcholine Receptor alpha 4 beta 2

    NARCIS (Netherlands)

    van der Zanden, Esmerij P.; Snoek, Susanne A.; Heinsbroek, Sigrid E.; Stanisor, Oana I.; Verseijden, Caroline; Boeckxstaens, Guy E.; Peppelenbosch, Maikel P.; Greaves, David R.; Gordon, Siamon; de Jonge, Wouter J.

    2009-01-01

    BACKGROUND & AIMS: The vagus nerve negatively regulates macrophage cytokine production via the release of acetylcholine (ACh) and activation of nicotinic acetylcholine receptors (nAChR). In various models of intestinal inflammation, vagus nerve efferent stimulation ameliorates disease. Given the act

  15. INHIBITORY EFFECTS OF VOLATILE ORGANIC COMPOUNDS ON NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS.

    Science.gov (United States)

    INHIBITORY EFFECTS OF VOLATILE ORGANIC COMPOUNDS ON NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS. A.S. Bale*; P.J. Bushnell; C.A. Meacham; T.J. Shafer Neurotoxicology Division, NHEERL, ORD, US Environmental Protection Agency, Research Triangle Park, NC, USA Toluene (TOL...

  16. 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...

  17. 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...

  18. Effect of a nicotinic acetylcholine receptor agonists and antagonists on motor function in mice

    Science.gov (United States)

    Nicotinic acetylcholine receptors (nAChR) are ligand-gated cation channels found throughout the body, and serve to mediate diverse physiological functions. Muscle-type nAChR located in the motor endplate region of muscle fibers play an integral role in muscle contraction and thus motor function. The...

  19. Functional aspects of dexamethasone upregulated nicotinic acetylcholine receptors in C2C12 myotubes

    NARCIS (Netherlands)

    Maestrone, E; Lagostena, L; Henning, RH; DenHertog, A; Nobile, M

    1995-01-01

    Three days of treatment with the glucocorticoid dexamethasone (1 nM-mu M) induced a concentration-dependent up-regulation of muscle nicotinic acetylcholine receptor (nAChR) in C2C12 mouse myotubes (EC(50)=10+/-7.3 nM), as assessed by [H-3]alpha-BuTx binding. The maximum increase in binding amounted

  20. Nicotine alpha 4 beta 2 receptor-mediated free calcium in an animal model of facial nucleus injury

    Institute of Scientific and Technical Information of China (English)

    Dawei Sun; Wenhai Sun; Yanqing Wang; Fugao Zhu; Rui Zhou; Yanjun Wang; Banghua Liu; Xiuming Wan; Huamin Liu

    2010-01-01

    Previous studies have demonstrated that the cholinergic system,via nicotinic receptors,regulates intracellular free calcium levels in the facial nucleus under normal physiological conditions.However,the regulation of nicotinic receptors on free calcium levels following facial nerve injury remains unclear.In the present study,an animal model of facial nerve injury was established,and changes in nicotinic receptor expression following facial nerve injury in rats were detected using reverse transcription polymerase chain reaction.Nicotinic receptor-mediated changes of free calcium levels following facial nucleus injury were determined by laser confocal microscopy.Results showed no significant difference in nicotinic receptor expression between the normal group and the affected facial nerve nucleus.The nicotinic receptor α4β2 subtype increased free calcium levels following facial nerve injury by promoting calcium transmembrane influx,and L-type voltage-gated calcium channel-mediated influx of calcium ions played an important role in promoting calcium transmembrane influx.The nicotinic receptor-mediated increase of free calcium levels following facial nerve injury provides an important mechanism for the repair of facial nerve injury.

  1. 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

  2. Indolizidine (-)-235B' and related structural analogs: discovery of nicotinic receptor antagonists that inhibit nicotine-evoked [3H]dopamine release.

    Science.gov (United States)

    Pivavarchyk, Marharyta; Smith, Andrew M; Zhang, Zhenfa; Zhou, Dejun; Wang, Xu; Toyooka, Naoki; Tsuneki, Hiroshi; Sasaoka, Toshiyasu; McIntosh, J Michael; Crooks, Peter A; Dwoskin, Linda P

    2011-05-11

    Although several therapeutic agents are available to aid in tobacco smoking cessation, relapse rates continue to be high, warranting the development of alternative pharmacotherapies. Nicotine-evoked dopamine release from its presynaptic terminals in the central nervous system leads to reward which maintains continued tobacco use. The ability of indolizidine (-)-235B' and a sub-library of structurally related analogs to inhibit nicotine-evoked [(3)H]dopamine release from rat striatal slices was determined in the current study. Indolizidine (-)-235B' inhibited nicotine-evoked [(3)H]dopamine release in a concentration-dependent manner (IC(50)=42 nM, I(max)=55%). Compound (-)-237D, the double bond-reduced analog, afforded the greatest inhibitory potency (IC(50)=0.18 nM, I(max)=76%), and was 233-fold more potent than indolizidine (-)-235B'. The des-8-methyl aza-analog of indolizidine (-)-235B', ZZ-272, also inhibited nicotine-evoked [(3)H]dopamine release (IC(50)=413 nM, I(max)=59%). Concomitant exposure to maximally effective concentrations of indolizidine (-)-235B', ZZ-272 or (-)-237D with a maximally effective concentration of α-conotoxin MII, a selective antagonist for α6β2-containing nicotinic receptors, resulted in inhibition of nicotine-evoked [(3)H]dopamine release no greater than that produced by each compound alone. The latter results suggest that indolizidine (-)-235B', (-)-237D, ZZ-272 and α-conotoxin MII inhibit the same α-conotoxin MII-sensitive nicotinic receptor subtypes. Thus, indolizidine (-)-235B' and its analogs act as antagonists of α6β2-nicotinic receptors and constitute a novel structural scaffold for the discovery of pharmacotherapies for smoking cessation.

  3. Role of the nicotinic acetylcholine receptor in Alzheimer's disease pathology and treatment.

    Science.gov (United States)

    Lombardo, Sylvia; Maskos, Uwe

    2015-09-01

    Alzheimer's Disease (AD) is the major form of senile dementia, characterized by neuronal loss, extracellular deposits, and neurofibrillary tangles. It is accompanied by a loss of cholinergic tone, and acetylcholine (ACh) levels in the brain, which were hypothesized to be responsible for the cognitive decline observed in AD. Current medication is restricted to enhancing cholinergic signalling for symptomatic treatment of AD patients. The nicotinic acetylcholine receptor family (nAChR) and the muscarinic acetylcholine receptor family (mAChR) are the target of ACh in the brain. Both families of receptors are affected in AD. It was demonstrated that amyloid beta (Aβ) interacts with nAChRs. Here we discuss how Aβ activates or inhibits nAChRs, and how this interaction contributes to AD pathology. We will discuss the potential role of nAChRs as therapeutic targets. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.

  4. Prenatal nicotine-exposure alters fetal autonomic activity and medullary neurotransmitter receptors: implications for sudden infant death syndrome.

    Science.gov (United States)

    Duncan, Jhodie R; Garland, Marianne; Myers, Michael M; Fifer, William P; Yang, May; Kinney, Hannah C; Stark, Raymond I

    2009-11-01

    During pregnancy, exposure to nicotine and other compounds in cigarette smoke increases the risk of the sudden infant death syndrome (SIDS) two- to fivefold. Serotonergic (5-HT) abnormalities are found, in infants who die of SIDS, in regions of the medulla oblongata known to modulate cardiorespiratory function. Using a baboon model, we tested the hypothesis that prenatal exposure to nicotine alters 5-HT receptor and/or transporter binding in the fetal medullary 5-HT system in association with cardiorespiratory dysfunction. At 87 (mean) days gestation (dg), mothers were continuously infused with saline (n = 5) or nicotine (n = 5) at 0.5 mg/h. Fetuses were surgically instrumented at 129 dg for cardiorespiratory monitoring. Cesarean section delivery and retrieval of fetal medulla were performed at 161 (mean) dg for autoradiographic analyses of nicotinic and 5-HT receptor and transporter binding. In nicotine-exposed fetuses, high-frequency heart rate variability was increased 55%, possibly reflecting increases in the parasympathetic control of heart rate. This effect was more pronounced with greater levels of fetal breathing and age. These changes in heart rate variability were associated with increased 5-HT(1A) receptor binding in the raphé obscurus (P = 0.04) and increased nicotinic receptor binding in the raphé obscurus and vagal complex (P < 0.05) in the nicotine-exposed animals compared with controls (n = 6). The shift in autonomic balance in the fetal primate toward parasympathetic predominance with chronic exposure to nicotine may be related, in part, to abnormal 5-HT-nicotine alterations in the raphé obscurus. Thus increased risk for SIDS due to maternal smoking may be partly related to the effects of nicotine on 5-HT and/or nicotinic receptors.

  5. Differential Regulation of α7 Nicotinic Receptor Gene (CHRNA7) Expression in Schizophrenic Smokers

    OpenAIRE

    Mexal, Sharon; Berger, Ralph; Logel, Judy; Ross, Randal G.; Freedman, Robert; Leonard, Sherry

    2009-01-01

    The α7 neuronal nicotinic receptor gene (CHRNA7) has been implicated in the pathophysiology of schizophrenia by genetic and pharmacological studies. Expression of the α7* receptor, as measured by [125I]α-bungarotoxin autoradiography, is decreased in postmortem brain of schizophrenic subjects compared to non-mentally ill controls. Most schizophrenic patients are heavy smokers, with high levels of serum cotinine. Smoking changes the expression of multiple genes and differentially regulates gene...

  6. Age-related decline in nicotinic receptor availability with [123I]5-IA-85380 SPECT

    OpenAIRE

    2008-01-01

    Human postmortem studies have reported decreases with age in high affinity nicotine binding in brain. We investigated the effect of age on β2-containing nicotinic acetylcholine receptor (β2-nAChR) availability in eight brain regions of living human subjects using the ligand [123I]5-IA-85380 ([123I]5-IA) and single photon emission computed tomography (SPECT). Healthy, nonsmokers (N=47) ranging in age from 18-85 were administered [123I]5-IA using a bolus plus constant infusion paradigm and imag...

  7. Subtype-selective nicotinic acetylcholine receptor agonists enhance the responsiveness to citalopram and reboxetine in the mouse forced swim test.

    Science.gov (United States)

    Andreasen, Jesper T; Nielsen, Elsebet Ø; Christensen, Jeppe K; Olsen, Gunnar M; Peters, Dan; Mirza, Naheed R; Redrobe, John P

    2011-10-01

    Nicotine increases serotonergic and noradrenergic neuronal activity and facilitates serotonin and noradrenaline release. Accordingly, nicotine enhances antidepressant-like actions of reuptake inhibitors selective for serotonin or noradrenaline in the mouse forced swim test and the mouse tail suspension test. Both high-affinity α4β2 and low-affinity α7 nicotinic acetylcholine receptor subtypes are implicated in nicotine-mediated release of serotonin and noradrenaline. The present study therefore investigated whether selective agonism of α4β2 or α7 nicotinic acetylcholine receptors would affect the mouse forced swim test activity of two antidepressants with distinct mechanisms of action, namely the selective serotonin reuptake inhibitor citalopram and the noradrenaline reuptake inhibitor reboxetine. Subthreshold and threshold doses of citalopram (3 and 10 mg/kg) or reboxetine (10 and 20 mg/kg) were tested alone and in combination with the novel α4β2-selective partial nicotinic acetylcholine receptor agonist, NS3956 (0.3 and 1.0 mg/kg) or the α7-selective nicotinic acetylcholine receptor agonist, PNU-282987 (10 and 30 mg/kg). Alone, NS3956 and PNU-282987 were devoid of activity in the mouse forced swim test, but both 1.0 mg/kg NS3956 and 30 mg/kg PNU-282987 enhanced the effect of citalopram and also reboxetine. The data suggest that the activity of citalopram and reboxetine in the mouse forced swim test can be enhanced by agonists at either α4β2 or α7 nicotinic acetylcholine receptors, suggesting that both nicotinic acetylcholine receptor subtypes may be involved in the nicotine-enhanced action of antidepressants.

  8. The Nicotinic Acetylcholine Receptor α5 Subunit Plays a Key Role in Attention Circuitry and Accuracy

    Science.gov (United States)

    Bailey, Craig D. C.; De Biasi, Mariella; Fletcher, Paul J.; Lambe, Evelyn K.

    2010-01-01

    Stimulation of the prefrontal cortex by acetylcholine is critical for attention; however, the cellular mechanisms underlying its influence on attention pathways within the brain are not well understood. Pyramidal neurons in layer VI of the prefrontal cortex are believed to play an important role in this process because they are excited by acetylcholine and provide a major source of feedback projections to the thalamus. Here, we show using whole-cell electrophysiology that the relatively rare α5 subunit of the nicotinic acetylcholine receptor powerfully enhances nicotinic currents in layer VI pyramidal neurons in prefrontal cortical brain slices from adult mice. In addition, behavioral experiments using the five-choice serial reaction time test show that the presence of the nicotinic receptor α5 subunit also increases the accuracy of adult mice on this visual attention task under highly demanding conditions. Together, these findings demonstrate a novel and important role for the nicotinic receptor α5 subunit in adult brain circuitry required for attentional performance. PMID:20610759

  9. Beta 2 subunit-containing nicotinic receptors mediate acute nicotine-induced activation of calcium/calmodulin-dependent protein kinase II-dependent pathways in vivo.

    Science.gov (United States)

    Jackson, K J; Walters, C L; Damaj, M I

    2009-08-01

    Nicotine is the addictive component of tobacco, and successful smoking cessation therapies must address the various processes that contribute to nicotine addiction. Thus, understanding the nicotinic acetylcholine receptor (nAChR) subtypes and subsequent molecular cascades activated after nicotine exposure is of the utmost importance in understanding the progression of nicotine dependence. One possible candidate is the calcium/calmodulin-dependent protein kinase II (CaMKII) pathway. Substrates of this kinase include the vesicle-associated protein synapsin I and the transcription factor cAMP response element-binding protein (CREB). The goal of these studies was to examine these postreceptor mechanisms after acute nicotine treatment in vivo. We first show that administration of nicotine increases CaMKII activity in the ventral tegmental area (VTA), nucleus accumbens (NAc), and amygdala. In beta2 nAChR knockout (KO) mice, nicotine does not induce an increase in kinase activity, phosphorylated (p)Synapsin I, or pCREB. In contrast, alpha7 nAChR KO mice show nicotine-induced increases in CaMKII activity and pCREB, similar to their wild-type littermates. Moreover, we show that when animals are pretreated with the CaMKII inhibitors 4-[(2S)-2-[(5-isoquinolinylsulfonyl) methylamino]-3-oxo-3-(4-phenyl-1-piperazinyl)propyl]phenyl isoquinolinesulfonic acid ester (KN-62) and N-[2-[[[3-(4-chlorophenyl)-2 propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulphonamide (KN-93), nicotine-induced increase in the kinase activity and pCREB was attenuated in the VTA and NAc, whereas pretreatment with (2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine, phosphate) (KN-92), the inactive analog, did not alter the nicotine-induced increase in pCREB. Taken together, these data suggest that the nicotine-induced increase in CaMKII activity may correlate with the nicotine-induced increase in pSynapsin I and pCREB in the VTA and NAc via beta2

  10. Expression profile of nicotinic acetylcholine receptor subunits in the brain of HIV-1 transgenic rats given chronic nicotine treatment.

    Science.gov (United States)

    Cao, Junran; Nesil, Tanseli; Wang, Shaolin; Chang, Sulie L; Li, Ming D

    2016-10-01

    Abuse of addictive substances, including cigarettes, is much greater in HIV-1-infected individuals than in the general population and challenges the efficiency of highly active anti-retroviral therapy (HAART). The HIV-1 transgenic (HIV-1Tg) rat, an animal model used to study drug addiction in HIV-1-infected patients on HAART, displays abnormal neurobehavioral responses to addictive substances. Given that the cholinergic system plays an essential part in the central reward circuitry, we evaluated the expression profile of nine nicotinic acetylcholine receptor (nAChR) subunit genes in the central nervous system (CNS) of HIV-1Tg rats. We found that nAChR subunits were differentially expressed in various brain regions in HIV-1Tg rats compared to F344 control rats, with more subunits altered in the ventral tegmental area (VTA) and nucleus accumbens (NAc) of the HIV-1Tg rats than in other brain regions. We also found that chronic nicotine treatment (0.4 mg/kg/day) decreased the mRNA expression of nAChR subunits α6, β3, and β4 in the VTA of HIV-1Tg rats, whereas expression of α4 and α6 subunits in the NAc increased. No such changes were observed in F344 rats. Together, our data suggest that HIV-1 proteins alter the expression of nAChRs, which may contribute to the vulnerability to cigarette smoking addiction in HIV-1 patients.

  11. Functional contribution of alpha3L8' to the neuronal nicotinic alpha3 receptor.

    Science.gov (United States)

    Nieves-Cintrón, Madeline; Caballero-Rivera, Daniel; Silva, Walter I; Navedo, Manuel F; Lasalde-Dominicci, José A

    2008-10-01

    The role of position L8', located in transmembrane domain 1 of the neuronal nicotinic alpha3 subunit, was characterized by using two-electrode voltage clamp in Xenopus oocytes. Four amino acids (Ala, Ser, Phe, and Tyr) were inserted at this conserved position, and the mutant subunit was coexpressed with either wild-type beta2 or beta4 subunits. These substitutions led to significant alterations in the pharmacodynamic parameters of cholinergic agents, resulting in loss of function. Ala and Ser substitutions resulted in losses in agonist (ACh, nicotine, and DMPP) potency and intrinsic activity at both alpha3beta2 and alpha3beta4 receptors. Similarly, significant changes in antagonist potency were produced by the Ala and Ser substitutions. Phe and Tyr mutations did not alter the receptor's EC(50) for ACh or nicotine but reduced the EC(50) for DMPP at both receptors. The Phe mutation also reduced the intrinsic activity of all agonists tested at both receptors. The Tyr mutation, though, led to a decrease in intrinsic activity for all agonists at the alpha3beta2 receptor, yet resulted in no changes for DMPP, a decrease for nicotine, and an increase for ACh at the alpha3beta4 receptor. The most dramatic changes in the receptor's functional properties were produced by substitutions that introduced the largest changes in amino acid volume. Additional replacements (Gly, Thr, and Val) suggested an inverse correlation between amino acid volume at position alpha3L8' and EC(50) for alpha3beta4 nAChRs; however, alpha3beta2 nAChRs displayed a nonlinear correlation. These data demonstrate that structural alterations at position alpha3L8' could propagate to the agonist-binding site.

  12. Effects of the nicotinic receptor partial agonists varenicline and cytisine on the discriminative stimulus effects of nicotine in rats.

    Science.gov (United States)

    LeSage, Mark G; Shelley, David; Ross, Jason T; Carroll, F Ivy; Corrigall, William A

    2009-01-01

    The nicotinic partial agonist varenicline (VCL) is a recently approved medication for the treatment of tobacco dependence, yet very little preclinical research on this drug has been published. The present experiment examined the nicotinic partial agonist properties of VCL and its parent compound, cytisine (CYT), in a nicotine discrimination assay. Rats were trained to discriminate nicotine (0.4 mg/kg, s.c.) from saline using a two-lever discrimination procedure, followed by generalization and antagonism tests with VCL and CYT. Antagonism was examined across a range of nicotine doses. In generalization tests, VCL produced a maximum of 63% responding on the nicotine-appropriate lever, indicating partial generalization. In antagonism tests, VCL decreased the % responding on the nicotine-appropriate lever at 0.2 and 0.4 mg/kg nicotine, indicating antagonism of nicotine's discriminative stimulus effects. No dose of VCL produced significant effects on response rate. The two highest doses of CYT weakly substituted for nicotine, producing a maximum of 23% nicotine-appropriate responding. CYT produced a weak antagonism of the discrimination of moderate nicotine doses, but not of the training dose. These results demonstrate that VCL and CYT partially generalize to and partially antagonize nicotine's discriminative stimulus effects, consistent with a partial agonist mechanism of action.

  13. Nicotinic Acetylcholine Receptor Gene Family of the Pea Aphid, Acyrthosiphon pisum

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-peng; LIN Ke-jian; LIU Yang; GUI Fu-rong; WANG Gui-rong

    2013-01-01

    The nicotinic acetylcholine receptors (nAchRs) are cholinergic receptors that form ligand-gated ion channels by ifve subunits in insect and vertebrate nervous systems. The insect nAChR is the molecular target of a class of insecticides, neonicotinoids. Here, we identiifed and cloned 11 candidate nAChR subunit genes in Acyrthosiphon pisum using genome-based bioinformatics combined modern molecular techniques. Most A. pisum nAChRs including α1, α2, α3, α4, α6, α8, and β1 show highly sequence identities with the counterparts of other insects examined. Expression proifles analysis showed that all subunit genes were expressed in adult head. At least two subunits have alternative splicing that obviously increase A. pisum nicotinic receptor diversity. This study will be invaluable for exploring the molecular mechanisms of neonicotinoid-like insecticides in sucking pests, and for ultimately establishing the screening platform of novel insecticides.

  14. Tritiated-nicotine- and /sup 125/I-alpha-bungarotoxin-labeled nicotinic receptors in the interpeduncular nucleus of rats. II. Effects of habenular destruction

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, P.B.; Hamill, G.S.; Nadi, N.S.; Jacobowitz, D.M.; Pert, A.

    1986-09-15

    The cholinergic innervation of the interpeduncular nucleus (IPN) is wholly extrinsic and is greatly attenuated by bilateral habenular destruction. We describe changes in the labeling of putative nicotinic receptors within this nucleus at 3, 5, or 11 days after bilateral habenular lesions. Adjacent tissue sections of the rat IPN were utilized for /sup 3/H-nicotine and /sup 125/I-alpha-bungarotoxin (/sup 125/I-BTX) receptor autoradiography. Compared to sham-operated controls, habenular destruction significantly reduced autoradiographic /sup 3/H-nicotine labeling in rostral (-25%), intermediate (-13%), and lateral subnuclei (-36%). Labeling in the central subnucleus was unchanged. Loss of labeling was maximal at the shortest survival time (3 days) and did not change thereafter. In order to establish whether this loss was due to a reduction in the number or the affinity of /sup 3/H-nicotine-binding sites, a membrane assay was performed on microdissected IPN tissue from rats that had received surgery 3 days previously. Bilateral habenular lesions produced a 35% reduction of high-affinity /sup 3/H-nicotine-binding sites, with no change in binding affinity. Bilateral habenular lesions reduced /sup 125/I-BTX labeling in the intermediate subnuclei, and a slight increase occurred in the rostral subnucleus. In the lateral subnuclei, /sup 125/I-BTX labeling was significantly reduced (27%) at 3 days but not at later survival times. In view of the known synaptic morphology of the habenulointerpeduncular tract, it is concluded that a subpopulation of /sup 3/H-nicotine binding sites within the IPN is located on afferent axons and/or terminals. This subpopulation, located within rostral, intermediate, and lateral subnuclei, may correspond to presynaptic nicotinic cholinergic receptors. Sites that bind /sup 125/I-BTX may include a presynaptic subpopulation located in the lateral and possibly the intermediate subnuclei.

  15. Cytisine binds with similar affinity to nicotinic alpha4beta2 receptors on the cell surface and in homogenates.

    Science.gov (United States)

    Zhang, Jessie; Steinbach, Joe Henry

    2003-01-03

    Cytisine and nicotine bound to specific sites in homogenates prepared from HEK 293 cells which stably express human neuronal nicotinic alpha4 and beta2 subunits. The number of sites was the same for both ligands and nicotine was a full competitive inhibitor of cytisine binding. However, when binding was done to intact cells the number of binding sites per cell for nicotine was approximately 4-fold the number of sites for cytisine. Nicotine fully blocked cytisine binding, but cytisine only partially blocked nicotine binding to intact cells. When cells were permeabilized with saponin, the number of sites for nicotine was unchanged, while the number of sites for cytisine was increased, and cytisine was able to fully block nicotine binding. These data indicate that cytisine binds only to surface receptors on intact cells. The apparent affinity of cytisine for surface receptors (K(d)=0.8 nM) was not significantly different from that for receptors in the cell homogenate (0.3 nM).

  16. Nootropic alpha7 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

    2007-05-08

    Activation of brain alpha7 nicotinic acetylcholine receptors (alpha7 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 alpha7 nAChRs would deliver the clinically validated benefits of allosterism to these indications. We have generated a selective alpha7 nAChR-positive allosteric modulator (PAM) from a library of GABAA receptor PAMs. Compound 6 (N-(4-chlorophenyl)-alpha-[[(4-chloro-phenyl)amino]methylene]-3-methyl-5-isoxazoleacet-amide) evokes robust positive modulation of agonist-induced currents at alpha7 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 alpha7 nAChRs, with therapeutic potential in CNS diseases with cognitive dysfunction.

  17. In vivo chronic nicotine exposure differentially and reversibly affects upregulation and stoichiometry of α4β2 nicotinic receptors in cortex and thalamus.

    Science.gov (United States)

    Fasoli, F; Moretti, M; Zoli, M; Pistillo, F; Crespi, A; Clementi, F; Mc Clure-Begley, T; Marks, M J; Gotti, C

    2016-09-01

    Studies with heterologous expression systems have shown that the α4β2 nicotinic acetylcholine receptor (nAChR) subtype can exist in two stoichiometries (with two [(α4)2(β2)3] or three [(α4)3(β2)2] copies of the α subunit in the receptor pentamer) which have different pharmacological and functional properties and are differently regulated by chronic nicotine treatment. However, the effects of nicotine treatment in vivo on native α4β2 nAChR stoichiometry are not well known. We investigated in C57BL/6 mice the in vivo effect of 14-day chronic nicotine treatment and subsequent withdrawal, on the subunit expression and β2/α4 subunit ratio of (3)H-epibatidine labeled α4β2*-nAChR in total homogenates of cortex and thalamus. We found that in basal conditions the ratio of the β2/α4 subunit in the cortex and thalamus is different indicating a higher proportion in receptors with (α4)2(β2)3 subunit stoichiometry in the thalamus. For cortex exposure to chronic nicotine elicited an increase in receptor density measured by (3)H-epibatidine binding, an increase in the α4 and β2 protein levels, and an increase in β2/α4 subunit ratio, that indicates an increased proportion of receptors with the (α4)2(β2)3 stoichiometry. For thalamus we did not find a significant increase in receptor density, α4 and β2 protein levels, or changes in β2/α4 subunit ratio. All the changes elicited by chronic nicotine in cortex were transient and returned to basal levels with an average half-life of 2.8 days following nicotine withdrawal. These data suggest that chronic nicotine exposure in vivo favors increased assembly of α4β2 nAChR containing three β2 subunits. A greater change in stoichiometry was observed for cortex (which has relatively low basal expression of (α4)2(β2)3 nAChR) than in thalamus (which has a relatively high basal expression of (α4)2(β2)3 nAChR).

  18. Modulation of nicotinic receptor channels by adrenergic stimulation in rat pinealocytes

    Science.gov (United States)

    Yoon, Jin-Young; Jung, Seung-Ryoung; Hille, Bertil

    2014-01-01

    Melatonin secretion from the pineal gland is triggered by norepinephrine released from sympathetic terminals at night. In contrast, cholinergic and parasympathetic inputs, by activating nicotinic cholinergic receptors (nAChR), have been suggested to counterbalance the noradrenergic input. Here we investigated whether adrenergic signaling regulates nAChR channels in rat pinealocytes. Acetylcholine or the selective nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) activated large nAChR currents in whole cell patch-clamp experiments. Norepinephrine (NE) reduced the nAChR currents, an effect partially mimicked by a β-adrenergic receptor agonist, isoproterenol, and blocked by a β-adrenergic receptor antagonist, propranolol. Increasing intracellular cAMP levels using membrane-permeable 8-bromoadenosine (8-Br)-cAMP or 5,6-dichlorobenzimidazole riboside-3′,5′-cyclic monophosphorothioate (cBIMPS) also reduced nAChR activity, mimicking the effects of NE and isoproterenol. Further, removal of ATP from the intracellular pipette solution blocked the reduction of nAChR currents, suggesting involvement of protein kinases. Indeed protein kinase A inhibitors, H-89 and Rp-cAMPS, blocked the modulation of nAChR by adrenergic stimulation. After the downmodulation by NE, nAChR channels mediated a smaller Ca2+ influx and less membrane depolarization from the resting potential. Together these results suggest that NE released from sympathetic terminals at night attenuates nicotinic cholinergic signaling. PMID:24553185

  19. 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

  20. Effects of the nicotinic receptor antagonist mecamylamine on ad-lib smoking behavior, topography, and nicotine levels in smokers with and without schizophrenia: a preliminary study.

    Science.gov (United States)

    McKee, Sherry A; Weinberger, Andrea H; Harrison, Emily L R; Coppola, Sabrina; George, Tony P

    2009-12-01

    Individuals with schizophrenia have higher plasma nicotine levels in comparison to non-psychiatric smokers, even when differences in smoking are equated. This difference may be related to how intensely cigarettes are smoked but this has not been well studied. Mecamylamine (MEC), a non-competitive nicotinic acetylcholine receptor (nAChR) antagonist, which has been shown to increase ad-lib smoking and to affect smoking topography, was used in the current study as a pharmacological probe to increase our understanding of smoking behavior, smoking topography, and resulting nicotine levels in smokers with schizophrenia. This preliminary study used a within-subject, placebo-controlled design in smokers with schizophrenia (n=6) and healthy control smokers (n=8) to examine the effects of MEC (10mg/day) on ad-lib smoking behavior, topography, nicotine levels, and tobacco craving across two smoking deprivation conditions (no deprivation and 12-h deprivation). MEC, compared to placebo, increased the number of cigarettes smoked and plasma nicotine levels. MEC increased smoking intensity and resulted in greater plasma nicotine levels in smokers with schizophrenia compared to controls, although these results were not consistent across deprivation conditions. MEC also increased tobacco craving in smokers with schizophrenia but not in control smokers. Our results suggest that antagonism of high-affinity nAChRs in smokers with schizophrenia may prompt compensatory smoking, increasing the intensity of smoking and nicotine exposure without alleviating craving. Further work is needed to assess whether nicotine levels are directly mediated by how intensely the cigarettes are smoked, and to confirm whether this effect is more pronounced in smokers with schizophrenia.

  1. Differential effects of M1 muscarinic receptor blockade and nicotinic receptor blockade in the dorsomedial striatum on response reversal learning

    Science.gov (United States)

    Tzavos, Arianna; Jih, Jane; Ragozzino, Michael E.

    2011-01-01

    The present studies determined whether blockade of M1-like muscarinic or nicotinic cholinergic receptors in the dorsomedial striatum affects acquisition or reversal learning of a response discrimination. Testing occurred in a modified cross-maze across two consecutive sessions. In the acquisition phase, a rat learned to turn to the left or to the right. In the reversal learning phase, a rat learned to turn in the opposite direction as required during acquisition. Experiment 1 investigated the effects of the M1-like muscarinic receptor antagonist, pirenzepine infused into the dorsomedial striatum on acquisition and reversal learning. Experiment 2 examined the effects of the nicotinic cholinergic antagonist, mecamylamine injected into the dorsomedial striatum on acquisition and reversal learning. Bilateral injections of pirenzepine at 10 µg, but not 1 µg, selectively impaired reversal learning. Analysis of the errors indicated that pirenzepine treatment did not impair the initial shift, but increased reversions back to the original response choice following the initial shift. Bilateral injections of mecamylamine, 6 or 18 µg, did not affect acquisition or reversal learning. The results suggest that activation of M1 muscarinic cholinergic receptors, but not nicotinic cholinergic receptors, in the dorsomedial striatum is important for facilitating the flexible shifting of response patterns. PMID:15302131

  2. Association of nicotinic acetylcholine receptor subunit alpha-4 polymorphisms with smoking behaviors in Chinese male smokers

    Institute of Scientific and Technical Information of China (English)

    CHU Cheng-jing; YANG Yan-chun; WEI Jin-xue; ZHANG Lan

    2011-01-01

    Background It has been reported that the nicotinic acetylcholine receptor subunit a4 gene (CHRNA4) might be associated with smoking behaviors in the previous studies. Up to now, there are few reports on the relationship between CHRNA4 and smoking initiation. In this study, we tried to explore the role of two polymorphisms in CHRNA4 (rs 1044396 and rs 1044397) in smoking initiation and nicotine dependence in Chinese male smokers.Methods Nine hundred and sixty-six Chinese male lifetime nonsmokers and smokers were assessed by the Fagerstr(o)m test for nicotine dependence (FTND), smoking quantity (SQ) and the heaviness of smoking index (HSI). All subjects were divided into four groups based on their tobacco use history and the FTND scores. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to find two polymorphisms of CHRNA4 in these subjects.Results The x2 test showed that rs1044396 was significantly associated with smoking initiation (x2=4.65, P=0.031),while both rs1044396 and rs1044397 were significantly associated with nicotine dependence (x2=5.42, P=0.020; x2=758,P=0.005). Furthermore, the T-G (3.9%) haplotype of rs1044396-rs1044397 showed significant association with smoking initiation (x2=6.30, P=0.012) and the C-G haplotype (58.9%) remained positive association with nicotine dependence (x2=8.64, P=0.003) after Bonferroni correction. The C-G haplotype also significantly increased the HSI (P=0.002) and FTND scores (P=0.001) after Bonferroni correction.Conclusion These findings suggest that CHRNA4 may be associated with smoking initiation and the C-G haplotype of rs1044396-rs1044397 might increase the vulnerability to nicotine dependence in Chinese male smokers.

  3. 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.

  4. Pre-clinical properties of the alpha 4 beta 2 nicotinic acetylcholine receptor partial agonists varenicline, cytisine and dianicline translate to clinical efficacy for nicotine dependence

    NARCIS (Netherlands)

    Rollema, H.; Shrikhande, A.; Ward, K. M.; Tingley, F. D.; Coe, J. W.; O'Neill, B. T.; Tseng, E.; Wang, E. Q.; Mather, R. J.; Hurst, R. S.; Williams, K. E.; de Vries, M.; Cremers, T.; Bertrand, S.; Bertrand, D.

    2010-01-01

    Background and purpose: Smoking cessation trials with three high-affinity partial agonists of alpha 4 beta 2 neuronal nicotinic acetylcholine receptors (nAChRs) have demonstrated differences in their clinical efficacy. This work examines the origin of the differences by taking into account brain exp

  5. Beta2-containing nicotinic acetylcholine receptors mediate calcium/calmodulin-dependent protein kinase-II and synapsin I protein levels in the nucleus accumbens after nicotine withdrawal in mice.

    Science.gov (United States)

    Jackson, Kia J; Imad Damaj, M

    2013-02-15

    Nicotinic acetylcholine receptors are calcium-permeable and the initial targets for nicotine. Studies suggest that calcium-dependent mechanisms mediate some behavioral responses to nicotine; however, the post-receptor calcium-dependent mechanisms associated with chronic nicotine and nicotine withdrawal remain unclear. The proteins calcium/calmodulin-dependent protein kinase II (CaMKII) and synapsin I are essential for neurotransmitter release and were shown to be involved in drug dependence. In the current study, using pharmacological techniques, we sought to (a) complement previously published behavioral findings from our lab indicating a role for calcium-dependent signaling in nicotine dependence and (b) expand on previously published acute biochemical and pharmacological findings indicating the relevance of calcium-dependent mechanisms in acute nicotine responses by evaluating the function of CaMKII and synapsin I after chronic nicotine and withdrawal in the nucleus accumbens, a brain region implicated in drug dependence. Male mice were chronically infused with nicotine for 14 days, and treated with the β2-selective antagonist dihydro-β-erythroidine (DHβE), or the α7 antagonist, methyllycaconitine citrate (MLA) 20min prior to dissection of the nucleus accumbens. Results show that phosphorylated and total CaMKII and synapsin I protein levels were significantly increased in the nucleus accumbens after chronic nicotine infusion, and reduced after treatment with DHβE, but not MLA. A spontaneous nicotine withdrawal assessment also revealed significant reductions in phosphorylated CaMKII and synapsin I levels 24h after cessation of nicotine treatment. Our findings suggest that post-receptor calcium-dependent mechanisms associated with nicotine withdrawal are mediated through β2-containing nicotinic receptors.

  6. Theoretical investigation of interaction between the set of ligands and α7 nicotinic acetylcholine receptor

    Science.gov (United States)

    Glukhova, O. E.; Prytkova, T. R.; Shmygin, D. S.

    2016-03-01

    Nicotinic acetylcholine receptors (nAChRs) are neuron receptor proteins that provide a transmission of nerve impulse through the synapses. They are composed of a pentametric assembly of five homologous subunits (5 α7 subunits for α7nAChR, for example), oriented around the central pore. These receptors might be found in the chemical synapses of central and peripheral nervous system, and also in the neuromuscular synapses. Transmembrane domain of the one of such receptors constitutes ion channel. The conductive properties of ion channel strongly depend on the receptor conformation changes in the response of binding with some molecule, f.e. acetylcholine. Investigation of interaction between ligands and acetylcholine receptor is important for drug design. In this work we investigate theoretically the interaction between the set of different ligands (such as vanillin, thymoquinone, etc.) and the nicotinic acetylcholine receptor (primarily with subunit of the α7nAChR) by different methods and packages (AutodockVina, GROMACS, KVAZAR, HARLEM, VMD). We calculate interaction energy between different ligands in the subunit using molecular dynamics. On the base of obtained calculation results and using molecular docking we found an optimal location of different ligands in the subunit.

  7. BDNF Up-Regulates α7 Nicotinic Acetylcholine Receptor Levels on Subpopulations of Hippocampal Interneurons

    OpenAIRE

    Massey, Kerri A; Zago, Wagner M.; Berg, Darwin K.

    2006-01-01

    In the hippocampus, brain-derived neurotrophic factor (BDNF) regulates a number of synaptic components. Among these are nicotinic acetylcholine receptors containing α7 subunits (α7-nAChRs), which are interesting because of their relative abundance in the hippocampus and their high relative calcium permeability. We show here that BDNF elevates surface and intracellular pools of α7-nAChRs on cultured hippocampal neurons and that glutamatergic activity is both necessary and sufficient for the ef...

  8. The nicotinic acetylcholine receptor gene family of the honey bee, Apis mellifera

    OpenAIRE

    Jones, Andrew K.; Raymond-Delpech, Valerie; Steeve H Thany; Gauthier, Monique; Sattelle, David B.

    2006-01-01

    Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission and play roles in many cognitive processes. They are under intense research as potential targets of drugs used to treat neurodegenerative diseases and neurological disorders such as Alzheimer's disease and schizophrenia. Invertebrate nAChRs are targets of anthelmintics as well as a major group of insecticides, the neonicotinoids. The honey bee, Apis mellifera, is one of the most beneficial insects worldw...

  9. Nicotinic Acetylcholine Receptor Signalling: Roles in Alzheimer's Disease and Amyloid Neuroprotection

    OpenAIRE

    2009-01-01

    Alzheimer's disease (AD), the major contributor to dementia in the elderly, involves accumulation in the brain of extracellular plaques containing the β-amyloid protein (Aβ) and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. AD is also characterized by a loss of neurons, particularly those expressing nicotinic acetylcholine receptors (nAChRs), thereby leading to a reduction in nAChR numbers. The Aβ1–42 protein, which is toxic to neurons, is critical to the onset and...

  10. 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...Army Medical Research and Materiel Command Fort Detrick, Maryland 21702-5012 DISTRIBUTION STATEMENT: Approved for public release; distribution...searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send

  11. A fluorinated quinuclidine benzamide named LMA 10203 acts as an agonist of insect nicotinic acetylcholine receptors.

    Science.gov (United States)

    Mathé-Allainmat, Monique; Bodereau-Dubois, Béatrice; Lapied, Bruno; Lebreton, Jacques; Thany, Steeve H

    2012-06-01

    In the present study, we take advantage of the fact that cockroach dorsal unpaired median neurons express different nicotinic acetylcholine receptor subtypes to demonstrate that simple quinuclidine benzamides such as the 2-fluorinated benzamide LMA 10203, could act as an agonist of cockroach α-bungarotoxin-insensitive nicotinic acetylcholine receptor subtype, called nAChR2. Indeed, 1 mM LMA 10203 induced ionic currents which were partially blocked by 0.5 μM α-bungarotoxin and methyllycaconitine and completely blocked by 5 μM mecamylamine. Moreover, the current-voltage curve revealed that the ionic current induced by LMA 10203 increased from -30 mV to +20 mV confirming that it acted as an agonist of α-bungarotoxin-insensitive nAChR2. In addition, 1 mM LMA 10203 induced a depolarization of the sixth abdominal ganglion and this neuroexcitatory activity was completely blocked by 5 μM mecamylamine. These data suggest that nAChR2 was also expressed at the postsynaptic level on the synapse between the cercal afferent nerve and the giant interneurons. Interestingly, despite LMA 10203 being an agonist of cockroach nicotinic receptors, it had a poor insecticidal activity. We conclude that LMA 10203 could be used as an interesting compound to identify specific insect nAChR subtypes.

  12. Electrophysiological characterization of nicotinic acetylcholine receptors in cat petrosal ganglion neurons in culture: effects of cytisine and its bromo derivatives.

    Science.gov (United States)

    Varas, Rodrigo; Valdés, Viviana; Iturriaga-Vásquez, Patricio; Cassels, Bruce K; Iturriaga, Rodrigo; Alcayaga, Julio

    2006-02-09

    Petrosal ganglion neurons are depolarized and fire action potentials in response to acetylcholine and nicotine. However, little is known about the subtype(s) of nicotinic acetylcholine receptors involved, although alpha4 and alpha7 subunits have been identified in petrosal ganglion neurons. Cytisine, an alkaloid unrelated to nicotine, and its bromo derivatives are agonists exhibiting different affinities, potencies and efficacies at nicotinic acetylcholine receptors containing alpha4 or alpha7 subunits. To characterize the receptors involved, we studied the effects of these agonists and the nicotinic acetylcholine receptor antagonists hexamethonium and alpha-bungarotoxin in isolated petrosal ganglion neurons. Petrosal ganglia were excised from anesthetized cats and cultured for up to 16 days. Using patch-clamp technique, we recorded whole-cell currents evoked by 5-10 s applications of acetylcholine, cytisine or its bromo derivatives. Agonists and antagonists were applied by gravity from a pipette near the neuron surface. Neurons responded to acetylcholine, cytisine, 3-bromocytisine and 5-bromocytisine with fast inward currents that desensitized during application of the stimuli and were reversibly blocked by 1 microM hexamethonium or 10 nM alpha-bungarotoxin. The order of potency of the agonists was 3-bromocytisine > acetylcholine approximately = cytisine > 5-bromocytisine, suggesting that homomeric alpha7 neuronal nicotinic receptors predominate in cat petrosal ganglion neurons in culture.

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

    Science.gov (United States)

    Maldifassi, Maria C; Atienza, Gema; Arnalich, Francisco; López-Collazo, Eduardo; Cedillo, Jose L; Martín-Sánchez, Carolina; Bordas, Anna; Renart, Jaime; Montiel, Carmen

    2014-01-01

    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.

  14. 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.

  15. A cognitive phenotype for a polymorphism in the nicotinic receptor gene CHRNA4.

    Science.gov (United States)

    Greenwood, P M; Parasuraman, Raja; Espeseth, Thomas

    2012-04-01

    Drawing on converging behavioral, electrophysiological, and imaging evidence, we advance an hypothesis for a cognitive phenotype of a SNP in the CHRNA4 gene encoding the α(4) subunit of α(4)β(2) nicotinic receptors. First, we review evidence that visuospatial attention can be decomposed into several component processes. Secondly, we consider evidence that one component, redirection of attention, is modulated by the nicotinic cholinergic system. Third, we review evidence that nicotinic stimulation exerts effects at the network level. Fourth, we consider evidence that normal variation in this SNP exerts nicotine-like modulatory effects on visuospatial attention. Fifth, we hypothesize that the cognitive phenotype of the CHRNA4 rs1044396 SNP is characterized by greater ability of T allele carriers to preferentially process events in the attentional focus compared to events outside the attentional focus. Finally, we consider effects of the CHNRA4 rs1044396 SNP on brain activity and cognition in light of our hypothesized cognitive phenotype. This hypothesis makes an important contribution to the development of cognitive phenomics by arguing for a cognitive phenotype of CHRNA4. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. 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.

  17. Nicotinic receptors and functional regulation of GABA cell microcircuitry in bipolar disorder and schizophrenia.

    Science.gov (United States)

    Benes, Francine M

    2012-01-01

    Studies of the hippocampus in postmortem brains from patients with schizophrenia and bipolar disorder have provided evidence for a defect of GABAergic interneurons. Significant decreases in the expression of GAD67, a marker for GABA cell function, have been found repeatedly in several different brain regions that include the hippocampus. In this region, nicotinic receptors are thought to play an important role in modulating the activity of GABAergic interneurons by influences of excitatory cholinergic afferents on their activity. In bipolar disorder, this influence appears to be particularly prominent in the stratum oriens of sectors CA3/2 and CA1, two sites where these cells constitute the exclusive neuronal cell type. In sector CA3/2, this layer receives a robust excitatory projection from the basolateral amygdala (BLA) and this is thought to play a central role in regulating GABA cells at this locus. Using laser microdissection, recent studies have focused selectively on these two layers and their associated GABA cells using microarray technology. The results have provided support for the idea that nicotinic cholinergic receptors play a particularly important role in regulating the activity of GABA neurons at these loci by regulating the progression of cell cycle and the repair of damaged DNA. In bipolar disorder, there is a prominent reduction in the expression of mRNAs for several different nicotinic subunit isoforms. These decreases could reflect a diminished influence of this receptor system on these GABA cells, particularly in sector CA3/2 where a preponderance of abnormalities have been observed in postmortem studies. In patients with bipolar disorder, excitatory nicotinic cholinergic fibers from the medial septum may converge with glutamatergic fibers from the BLA on GABAergic interneurons in the stratum oriens of CA3/2 and result in disturbances of their genomic and functional integrity, ones that may induce disruptions of the integration of

  18. Regulation of nicotinic receptor subtypes following chronic nicotinic agonist exposure in M10 and SH-SY5Y neuroblastoma cells

    DEFF Research Database (Denmark)

    Warpman, U; Friberg, L; Gillespie, A

    1998-01-01

    The present study further investigated whether nicotinic acetylcholine receptor (nAChR) subtypes differ in their ability to up-regulate following chronic exposure to nicotinic agonists. Seven nicotinic agonists were studied for their ability to influence the number of chick alpha4beta2 n......AChR binding sites stably transfected in fibroblasts (M10 cells) following 3 days of exposure. The result showed a positive correlation between the Ki values for binding inhibition and EC50 values for agonist-induced alpha4beta2 nAChR up-regulation. The effects of epibatidine and nicotine were further...... investigated in human neuroblastoma SH-SY5Y cells (expressing alpha3, alpha5, beta2, and beta4 nAChR subunits). Nicotine exhibited a 14 times lower affinity for the nAChRs in SH-SY5Y cells as compared with M10 cells, whereas epibatidine showed similar affinities for the nAChRs expressed in the two cell lines...

  19. NeuroD1 mediates nicotine-induced migration and invasion via regulation of the nicotinic acetylcholine receptor subunits in a subset of neural and neuroendocrine carcinomas.

    Science.gov (United States)

    Osborne, Jihan K; Guerra, Marcy L; Gonzales, Joshua X; McMillan, Elizabeth A; Minna, John D; Cobb, Melanie H

    2014-06-01

    Cigarette smoking is a major risk factor for acquisition of small cell lung cancer (SCLC). A role has been demonstrated for the basic helix-loop-helix transcription factor NeuroD1 in the pathogenesis of neural and neuroendocrine lung cancer, including SCLC. In the present study we investigate the possible function of NeuroD1 in established tumors, as well as actions early on in pathogenesis, in response to nicotine. We demonstrate that nicotine up-regulates NeuroD1 in immortalized normal bronchial epithelial cells and a subset of undifferentiated carcinomas. Increased expression of NeuroD1 subsequently leads to regulation of expression and function of the nicotinic acetylcholine receptor subunit cluster of α3, α5, and β4. In addition, we find that coordinated expression of these subunits by NeuroD1 leads to enhanced nicotine-induced migration and invasion, likely through changes in intracellular calcium. These findings suggest that aspects of the pathogenesis of neural and neuroendocrine lung cancers may be affected by a nicotine- and NeuroD1-induced positive feedback loop.

  20. Binding-gating coupling in a nondesensitizing alpha7 nicotinic receptor A single channel pharmacological study.

    Science.gov (United States)

    Bernal, José Antonio; Mulet, José; Castillo, Mar; Criado, Manuel; Sala, Salvador; Sala, Francisco

    2009-02-01

    The highly conserved alphaLys145 has been suggested to play an important role in the early steps of activation of the nicotinic acetylcholine receptor (nAChR) by acetylcholine. Both macroscopic and single channel currents were recorded in the slowly desensitizing mutants L248T- and K145A-L248T-alpha7 receptors expressed in Xenopus oocytes. On ACh-evoked currents, substitution of Lys145 by alanine showed the same effects that in wild type receptors: moderately decreased gating function and a more-than-expected loss of ACh potency, thus validating the experimental model. Single channel analysis quantitatively agreed with macroscopic data and revealed that impaired gating function in the double mutant alpha7K145A/L248T is the consequence of a slower opening rate, beta. Several nicotinic agonists were also studied, showing important features. Particularly, dimethylphenylpiperazinium (DMPP), acting as an antagonist in alpha7K145A, became a full agonist in alpha7K145A/L248T. Single channel analysis of DMPP-evoked currents showed effects of Lys145 removal similar to those observed with ACh. Data suggest that alpha7Lys145 facilitates the early steps of channel activation. Moreover, the slowly desensitizing mutant alpha7L248T could be an interesting tool for the study of channel activation in alpha7 receptors. Nevertheless, its extensively altered pharmacology precludes the simple extrapolation of pharmacological data obtained in singly mutated alpha7 receptors.

  1. 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.

  2. 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.

  3. Function of Partially Duplicated Human α7 Nicotinic Receptor Subunit CHRFAM7A Gene

    Science.gov (United States)

    de Lucas-Cerrillo, Ana M.; Maldifassi, M. Constanza; Arnalich, Francisco; Renart, Jaime; Atienza, Gema; Serantes, Rocío; Cruces, Jesús; Sánchez-Pacheco, Aurora; Andrés-Mateos, Eva; Montiel, Carmen

    2011-01-01

    The neuronal α7 nicotinic receptor subunit gene (CHRNA7) is partially duplicated in the human genome forming a hybrid gene (CHRFAM7A) with the novel FAM7A gene. The hybrid gene transcript, dupα7, has been identified in brain, immune cells, and the HL-60 cell line, although its translation and function are still unknown. In this study, dupα7 cDNA has been cloned and expressed in GH4C1 cells and Xenopus oocytes to study the pattern and functional role of the expressed protein. Our results reveal that dupα7 transcript was natively translated in HL-60 cells and heterologously expressed in GH4C1 cells and oocytes. Injection of dupα7 mRNA into oocytes failed to generate functional receptors, but when co-injected with α7 mRNA at α7/dupα7 ratios of 5:1, 2:1, 1:1, 1:5, and 1:10, it reduced the nicotine-elicited α7 current generated in control oocytes (α7 alone) by 26, 53, 75, 93, and 94%, respectively. This effect is mainly due to a reduction in the number of functional α7 receptors reaching the oocyte membrane, as deduced from α-bungarotoxin binding and fluorescent confocal assays. Two additional findings open the possibility that the dominant negative effect of dupα7 on α7 receptor activity observed in vitro could be extrapolated to in vivo situations. (i) Compared with α7 mRNA, basal dupα7 mRNA levels are substantial in human cerebral cortex and higher in macrophages. (ii) dupα7 mRNA levels in macrophages are down-regulated by IL-1β, LPS, and nicotine. Thus, dupα7 could modulate α7 receptor-mediated synaptic transmission and cholinergic anti-inflammatory response. PMID:21047781

  4. 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.

    2016-01-01

    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. PMID:21562921

  5. Gymnopilins, a product of a hallucinogenic mushroom, inhibit the nicotinic acetylcholine receptor.

    Science.gov (United States)

    Kayano, Tomohiko; Kitamura, Naoki; Miyazaki, Shunsuke; Ichiyanagi, Tsuyoshi; Shimomura, Norihiro; Shibuya, Izumi; Aimi, Tadanori

    2014-04-01

    Gymnopilins are substances produced in fruiting bodies of the hallucinogenic mushroom, Gymnopilus junonius. Although, only a few biological effects of gymnopilins on animal tissues have been reported, it is believed that gymnopilins are a key factor of the G. junonius poisoning. In the present study, we found that gymnopilins inhibited ACh-evoked responses in neuronal cell line, PC12 cell, and determine the underlying mechanism. Gymnopilins were purified from wild fruiting bodies of G. junonius collected in Japan. Ca(2+)-imaging revealed that gymnopilins reduced the amplitude of ACh-evoked [Ca(2+)]i rises by about 50% and abolished the ACh responses remaining in the presence of atropine. Gymnopilins greatly reduced the amplitude of [Ca(2+)]i rises evoked by nicotinic ACh receptor agonists, 1,1-Dimethyl-4-phenylpiperazinium iodide (DMPP) and nicotine. In the whole-cell voltage clamp recording, gymnopilins inhibited the DMPP-evoked currents, but did not affect the voltage-gated Ca(2+) channel currents. These results indicate that gymnopilins directly act on nicotinic ACh receptors and inhibit their activity. This biological action of gymnopilins may be one of the causes of the G. junonius poisoning.

  6. Effects of nicotine on emotional distraction of attentional orienting: evidence of possible moderation by dopamine type 2 receptor genotype.

    Science.gov (United States)

    Hammersley, Jonathan J; Rzetelny, Adam; Gilbert, David G; Rabinovich, Norka E; Small, Stacey L; Huggenvik, Jodi I

    2013-04-01

    Growing evidence suggests that attentional bias to, and distraction by, emotional stimuli may moderate affective states and motivation for nicotine and other drug use. The present study assessed the effects of nicotine and dopamine receptor genotype on distraction by emotional pictures, during a modified spatial attention task, in 46 overnight-deprived smokers. Relative to placebo, 14mg nicotine patch produced shorter overall reaction times (RTs) and individuals with two dopamine type 2 receptor (DRD2) A2 alleles exhibited the greatest RT benefit from nicotine following emotionally negative pictures after the longest cue-target delay (800ms), but benefitted least from nicotine following positive pictures after the shortest delay (400ms). In contrast, at the shortest delay, A1 carriers did not benefit from nicotine following emotionally negative pictures but did following positive ones. These genetic differences in the effects of nicotine on attention immediately following emotionally positive versus negative stimuli may reflect differential excitatory and inhibitory transmitter processes related to approach (reward) and avoidance (punishment) sensitivities of dopamine-related neural networks that support positive and negative affect. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. 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

    and modulating their function. Hence, changes in nAChR regulatory proteins such as Lynx proteins could underlie the dysregulation of nAChRs in AD. Using Western blotting, we detected bands corresponding to the Lynx proteins prostate stem cell antigen (PSCA) and Lypd6 in human cortex indicating that both proteins......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...... are present in the human brain. We further showed that PSCA forms stable complexes with the α4 nAChR subunit and decreases nicotine-induced extracellular-signal regulated kinase phosphorylation in PC12 cells. In addition, we analyzed protein levels of PSCA and Lypd6 in postmortem tissue of medial frontal...

  8. Differential regulation of alpha7 nicotinic receptor gene (CHRNA7) expression in schizophrenic smokers.

    Science.gov (United States)

    Mexal, Sharon; Berger, Ralph; Logel, Judy; Ross, Randal G; Freedman, Robert; Leonard, Sherry

    2010-01-01

    The alpha7 neuronal nicotinic receptor gene (CHRNA7) has been implicated in the pathophysiology of schizophrenia by genetic and pharmacological studies. Expression of the alpha7* receptor, as measured by [(125)I]alpha-bungarotoxin autoradiography, is decreased in postmortem brain of schizophrenic subjects compared to non-mentally ill controls. Most schizophrenic patients are heavy smokers, with high levels of serum cotinine. Smoking changes the expression of multiple genes and differentially regulates gene expression in schizophrenic hippocampus. We examined the effects of smoking on CHRNA7 expression in the same tissue and find that smoking differentially regulates expression of both mRNA and protein for this gene. CHRNA7 mRNA and protein levels are significantly lower in schizophrenic nonsmokers compared to control nonsmokers and are brought to control levels in schizophrenic smokers. Sufficient protein but low surface expression of the alpha7* receptor, seen in the autoradiographic studies, suggests aberrant assembly or trafficking of the receptor.

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

    DEFF Research Database (Denmark)

    Jensen, Anders A.; Gharagozloo, Parviz; Birdsall, Nigel J M

    2006-01-01

    of tertiary and quaternary analogues as well as bisquaternary dimers of strychnine and brucine at human alpha1 and alpha1beta glycine receptors and at a chimera consisting of the amino-terminal domain of the alpha7 nicotinic receptor (containing the orthosteric ligand binding site) and the ion channel domain...... of strychnine and brucine, none of the analogues displayed significant selectivity between the alpha1 and alpha1beta subtypes. The structure-activity relationships for the compounds at the alpha7/5-HT3 chimera were significantly different from those at the glycine receptors. Most strikingly, quaternization...... of strychnine and brucine with substituents possessing different steric and electronic properties completely eliminated the activity at the glycine receptors, whereas binding affinity to the alpha7/5-HT3 chimera was retained for the majority of the quaternary analogues. This study provides an insight...

  10. Nicotine Elevated Intracellular Ca2+ in Rat Airway Smooth Muscle Cells via Activating and Up-Regulating α7-Nicotinic Acetylcholine Receptor

    Directory of Open Access Journals (Sweden)

    Yongliang Jiang

    2014-02-01

    Full Text Available Background: Chronic obstructive pulmonary disease (COPD is characterized by airway remodeling with airway smooth muscle (ASM hypertrophy and hyperplasia. Since tobacco use is the key risk factor for the development of COPD and intracellular Ca2+ concentration ([Ca2+]i plays a major role in both cell proliferation and differentiation, we hypothesized that nicotinic acetylcholine receptor (nAChR activation plays a role in the elevation of [Ca2+]i in airway smooth muscle cells (ASMCs. Methods: We examined the expression of nAChR and characterized the functions of α7-nAChR in ASMCs. Results: RT-PCR analysis showed that α2-7, β2, and β3-nAChR subunits are expressed in rat ASMCs, with α7 being one of the most abundantly expressed subtypes. Chronic nicotine exposure increased α7-nAChR mRNA and protein expression, and elevated resting [Ca2+]i in cultured rat ASMCs. Acute application of nicotine evoked a rapid increase in [Ca2+]i in a concentration-dependent manner, and the response was significantly enhanced in ASMCs cultured with 1 µM nicotine for 48 hours. Nicotine-induced Ca2+ response was reversibly blocked by the α7-nAChR nicotinic antagonists, methyllycaconitine and α-bungarotoxin. Small interfering RNA suppression of α7-nAChR also substantially blunted the Ca2+ responses induced by nicotine. Conclusion: These observations suggest that nicotine elevates [Ca2+]i in ASMCs through α7-nAChR-mediated signals pathways, and highlight the possibility that α7-nAChR can be considered as a potential target for the treatment of airway remodeling.that nicotine elevates [Ca2+]i in ASMCs through α7-nAChR-mediated signals pathways, and highlight the possibility that α7-nAChR can be considered as a potential target for the treatment of airway remodeling.

  11. Halogenated cytisine derivatives as agonists at human neuronal nicotinic acetylcholine receptor subtypes.

    Science.gov (United States)

    Slater, Y E; Houlihan, L M; Maskell, P D; Exley, R; Bermúdez, I; Lukas, R J; Valdivia, A C; Cassels, B K

    2003-03-01

    Cytisine (cy) is a potent and competitive partial agonist at alpha4 subunit-containing nicotinic acetylcholine (nACh) receptors while at homomeric alpha7-nACh receptors it behaves as a full agonist with a relatively lower potency. In the present study, we assessed the effects of bromination or iodination of the pyridone ring of cy and N-methylcytisine (N-Me-cy) on the effects of these compounds on recombinant human (h) alpha7, halpha4beta2 and halpha4beta4 nACh receptors expressed in clonal cell lines and Xenopus oocytes. Halogenation at C(3) of cy or N-Me-cy usually brings about a marked increase in both affinity and efficacy at halpha7, halpha4beta2 and halpha4beta4 nACh, the extent of which depends on whether the halogen is bromine or iodine, and upon receptor subtype. The effects of halogenation at C(5) are strongly influenced by the specific halogen substituent so that bromination causes a decrease in both affinity and efficacy while iodination decreases affinity but its effects on efficacy range from a decrease (halpha7, halpha4beta4 nACh receptors) to a marked increase (halpha4beta2 nACh receptors). Based on these findings, which differ from those showing that neither the affinity nor efficacy of nicotine, 3-(2-azetidinylmethoxy)-pyridine or epibatidine are greatly affected by halogenation, dehalogenation or halogen exchange at equivalent positions, we suggest that cy, N-Me-cy and their halo-isosteres bind to neuronal nACh receptors in a different orientation allowing the halogen atom to interact with a hydrophobic halogen-accepting region within the predominantly hydrophobic agonist-binding pocket of the receptors.

  12. 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.

  13. The nicotinic receptor in the rat pineal gland is an alpha3beta4 subtype.

    Science.gov (United States)

    Hernandez, Susan C; Vicini, Stefano; Xiao, Yingxian; Dávila-García, Martha I; Yasuda, Robert P; Wolfe, Barry B; Kellar, Kenneth J

    2004-10-01

    The rat pineal gland contains a high density of neuronal nicotinic acetylcholine receptors (nAChRs). We characterized the pharmacology of the binding sites and function of these receptors, measured the nAChR subunit mRNA, and used subunit-specific antibodies to establish the receptor subtype as defined by subunit composition. In ligand binding studies, [3H]epibatidine ([3H]EB) binds with an affinity of approximately 100 pM to nAChRs in the pineal gland, and the density of these sites is approximately 5 times that in rat cerebral cortex. The affinities of nicotinic drugs for binding sites in the pineal gland are similar to those at alpha3beta4 nAChRs heterologously expressed in human embryonic kidney 293 cells. In functional studies, the potencies and efficacies of nicotinic drugs to activate or block whole-cell currents in dissociated pinealocytes match closely their potencies and efficacies to activate or block 86Rb+ efflux in the cells expressing heterologous alpha3beta4 nAChRs. Measurements of mRNA indicated the presence of transcripts for alpha3, beta2, and beta4 nAChR subunits but not those for alpha2, alpha4, alpha5, alpha6, alpha7, or beta3 subunits. Immunoprecipitation with subunit-specific antibodies showed that virtually all [3H]EB-labeled nAChRs contained alpha3 and beta4 subunits associated in one complex. The beta2 subunit was not associated with this complex. Taken together, these results indicate that virtually all of the nAChRs in the rat pineal gland are the alpha3beta4 nAChR subtype and that the pineal gland can therefore serve as an excellent and convenient model in which to study the pharmacology and function of these receptors in a native tissue.

  14. [Critical role of peptidic toxins in the functional and structural analysis of nicotinic acetylcholine receptors].

    Science.gov (United States)

    Fruchart-Gaillard, Carole; Ménez, André; Servent, Denis

    2005-01-01

    Animal toxins which interact on various receptors and channels have been often used in the studies of the functional roles of these targets. Nicotinic toxins have been purified from snake and cone venoms and are characterized by high affinity and various selectivity of interactions on the different nicotinic receptors subtypes. Since 30 years they have been used as molecular probes to identify, localize and purify these receptors. Furthermore, they have played a crucial role in the better understanding of their functional properties and have been useful in their structural studies. These peptidic toxins could be chemically synthetized or recombinantly expressed and nonnatural residues could be introduced in their sequences in order to delineate their functional interaction sites. The structural modelisation of toxin-nAChR interaction allows us to understand the antagonistic property of these toxins and open the way to the design of engineered ligands with predetermined specificity, useful as pharmacological tools or therapeutic agents in the numerous diseases involving this receptor family.

  15. 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...

  16. 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 an

  17. 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.

  18. Limitations of RNAi of α6 nicotinic acetylcholine receptor subunits for assessing the in vivo sensitivity to spinosad

    Institute of Scientific and Technical Information of China (English)

    Frank D.Rinkevich; Jeffrey G.Scott

    2013-01-01

    Spinosad is a widely used insecticide that exerts its toxic effect primarily through interactions with the nicotinic acetylcholine receptor.The α6 nicotinic acetyl-choline receptor subunit is involved in spinosad toxicity as demonstrated by the high levels of resistance observed in strains lacking α6.RNAi was performed against the Dα6 nicotinic acetylcholine receptor subunit in Drosophila melanogaster using the Ga14-UAS system to examine if RNAi would yield results similar to those of Dα6 null mutants.These Dα6-deficient flies were subject to spinosad contact bioassays to evaluate the role of the Dα6 nicotinic acetylcholine receptor subunit on spinosad sensitivity.The expression of Dα6 was reduced 60%-75% as verified by quantitative polymerase chain reaction.However,there was no change in spinosad sensitivity in D.melanogaster.We repeated RNAi experiments in Tribolium castaneum using injection of dsRNA for Tcasα6.RNAi of Tcasα6 did not result in changes in spinosad sensitivity,similar to results obtained with D.melanogaster.The lack of change in spinosad sensitivity in both D.melanogaster and T.castaneum using two routes of dsRNA administration shows that RNAi may not provide adequate conditions to study the role of nicotinic acetylcholine receptor subunits on insecticide sensitivity due to the inability to completely eliminate expression of the α6 subunit in both species.Potential causes for the lack of change in spinosad sensitivity are discussed.

  19. Immunohistochemistry Study on Androgen and Estrogen Receptors of Rat Seminal Vesicle Submitted to Simultaneous Alcohol-Nicotine Treatment

    Directory of Open Access Journals (Sweden)

    Mohsen Basiri

    2016-09-01

    Full Text Available Objective: Alcohol consumption is habitually accompanied by the use of other psychoactive substances, mostly tobacco. Nicotine and alcohol affect male accessory reproductive glands function. Most studies have been done on pathologic features of prostate, but there has been no systematic study on the seminal vesicle. Therefore, the aim of current study was to investigate the distribution of androgen receptor (AR and estrogen receptors-beta (ER-β immune reactivities following long-term treatment of alcohol, nicotine or a combination of both substances. Materials and Methods: In this experimental study, a total of 40 adult Wistar rats, nine weeks of age, were used. Animals were randomly divided into four groups, including: i. Control group receiving normal saline 0.09%, ii. Ethanol group receiving ethanol 20% (2 ml/kg, via gavage, iii. Nicotine group receiving nicotine (0.1 mg/kg, subcutaneous injection, and iv. Ethanol-nicotine group receiving simultaneous ethanol 20% (2 ml/kg and nicotine (0.1 mg/kg treatment. All treatment lasted for eight weeks. Prior to intracardiac perfusion, blood sample was collected from left ventricle. The seminal vesicles were isolated and processed for paraffin blocking. The sample tissues were then studied for distribution of AR and ER-β immunereactivities using immunohistochemical (IHC staining method. One way analysis of variance (ANOVA and Tukey’s test were performed for data analysis. A value of P<0.05 was considered significant. Results: Our results revealed that the lowest mean number of positive cells belonged to the animals of ethanol-nicotine group that was followed by the ethanol, nicotine, and control groups, respectively. However, there was no significant difference regarding serum testosterone level among experimental groups. Conclusion: It was concluded that combination of both ethanol and nicotine may be a crucial factor in the expression levels of AR and ER-β.

  20. 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

  1. 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

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

    Science.gov (United States)

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

    1999-01-01

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

  3. [Effects of steroid hormones on nicotinic acetylcholine receptor channel kinetics].

    Science.gov (United States)

    Nurowska, E; Dworakowska, B; Dołowy, K

    2000-01-01

    Classically steroid hormones acts through genomic mechanism. In the last period there is more evidence that some steroid hormones exert fast (in order of seconds) effects on membrane receptors. In the presented work we analysed the effects of some steroid hormones on muscle acetylcholine receptor (AChR) channel kinetics. We divided steroid hormone on two groups which exert different effects. The first group including hydrocortisone (HC), corticosterone (COR), dexamethasone decrease the mean open time increasing the number of openings in bursts. The effects do not depend on agonist concentration. Some effects of HC and COR are voltage-dependent. The mechanism of such voltage dependent action caused by steroids hormones that are uncharged molecules, is unknown. Some experiments suggest however that an agonist molecule is involved in the mechanism of steroid action. The second group consists of progesterone, some of its derivatives and deoxycorticosterone. For this group the most evident effect was decrease in the probability of openings without a decrease in the mean open time. The effect depends on agonist concentration, suggesting an involvement of an agonist molecule in the mechanism. For this hormones an involvement of an charged agonist molecule does not however induce a voltage dependency. Most probably two groups of steroids acts on different part of the AChR. The localization of a steroid action site can be crucial for inducing voltage dependency.

  4. 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.

  5. The effect of α7 nicotinic receptor activation on glutamatergic transmission in the hippocampus.

    Science.gov (United States)

    Cheng, Qing; Yakel, Jerrel L

    2015-10-15

    Nicotinic acetylcholine receptors (nAChRs) are expressed widely in the CNS, and mediate both synaptic and perisynaptic activities of endogenous cholinergic inputs and pharmacological actions of exogenous compounds (e.g., nicotine and choline). Behavioral studies indicate that nicotine improves such cognitive functions as learning and memory, however the cellular mechanism of these actions remains elusive. With help from newly developed biosensors and optogenetic tools, recent studies provide new insights on signaling mechanisms involved in the activation of nAChRs. Here we will review α7 nAChR's action in the tri-synaptic pathway in the hippocampus. The effects of α7 nAChR activation via either exogenous compounds or endogenous cholinergic innervation are detailed for spontaneous and evoked glutamatergic synaptic transmission and synaptic plasticity, as well as the underlying signaling mechanisms. In summary, α7 nAChRs trigger intracellular calcium rise and calcium-dependent signaling pathways to enhance glutamate release and induce glutamatergic synaptic plasticity.

  6. 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

    Lynx1 regulates synaptic plasticity in the brain by regulating nicotinic acetylcholine receptors (nAChRs). It is not known to which extent Lynx1 can bind to endogenous nAChR subunits in the brain or how this interaction is affected by Alzheimer's disease pathology. We apply affinity purification...... 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....... Incubation with Ws-Lynx1 decreases nicotine-mediated extracellular signal-regulated kinase phosphorylation in PC12 cells and striatal neurons, indicating that binding of Ws-Lynx1 is sufficient to inhibit signaling downstream of nAChRs. The effect of nicotine in PC12 cells is independent of α7 or α4β2 n...

  7. Recent developments in novel antidepressants targeting α4β2-nicotinic acetylcholine receptors.

    Science.gov (United States)

    Yu, Li-Fang; Zhang, Han-Kun; Caldarone, Barbara J; Eaton, J Brek; Lukas, Ronald J; Kozikowski, Alan P

    2014-10-23

    Nicotinic acetylcholine receptors (nAChRs) have been investigated for developing drugs that can potentially treat various central nervous system disorders. Considerable evidence supports the hypothesis that modulation of the cholinergic system through activation and/or desensitization/inactivation of nAChR holds promise for the development of new antidepressants. The introductory portion of this Miniperspective discusses the basic pharmacology that underpins the involvement of α4β2-nAChRs in depression, along with the structural features that are essential to ligand recognition by the α4β2-nAChRs. The remainder of this Miniperspective analyzes reported nicotinic ligands in terms of drug design considerations and their potency and selectivity, with a particular focus on compounds exhibiting antidepressant-like effects in preclinical or clinical studies. This Miniperspective aims to provide an in-depth analysis of the potential for using nicotinic ligands in the treatment of depression, which may hold some promise in addressing an unmet clinical need by providing relief from depressive symptoms in refractory patients.

  8. Prejunctional effects of the nicotinic ACh receptor agonist dimethylphenylpiperazinium at the rat neuromuscular junction.

    Science.gov (United States)

    Singh, S; Prior, C

    1998-09-01

    1. We have studied the effects of the nicotinic acetylcholine (ACh) receptor agonist dimethylphenylpiperazinium (DMPP) on the evoked release of ACh from motor terminals in the rat isolated hemidiaphragm using an electrophysiological approach. 2. DMPP (1-4 microM) had no effect on the rate of spontaneous quantal ACh release but increased the number of quanta of ACh released per impulse during 50 Hz stimulation. The DMPP-induced increase in evoked ACh release was dependent on the frequency of stimulation, being absent when it was reduced to 0.5 Hz, but was not Ca2+ dependent, being unaffected at 50 Hz by a 4-fold decrease in the extracellular Ca2+ concentration. 3. The facilitation of evoked ACh release at 50 Hz by 2 microM DMPP was abolished by 10 microM of the calmodulin antagonist W7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide hydrochloride) and, in the presence of W7, 2 microM DMPP depressed evoked ACh release at 0.5 Hz. The ability of the nicotinic ACh receptor antagonist vecuronium (1 microM) to depress evoked ACh release at 50 Hz was also abolished by 10 microM W7. 4. The present findings demonstrate, using an electrophysiological technique, that DMPP can produce changes in the evoked ACh release from rat motor nerve terminals that are consistent with the existence of facilitatory nicotinic ACh receptors on the motor nerve endings. Further, they indicate a role for calmodulin-dependent systems in this facilitatory effect of the compound.

  9. Desensitized nicotinic receptors that, however, afford cytoprotection in bovine chromaffin cells.

    Science.gov (United States)

    Egea, Javier; Hernández-Guijo, Jesús Miguel; Olivares, Roman; López, Manuela G; García, Antonio G

    2006-01-01

    Neuronal nicotinic receptors for acetylcholine (nAChRs) are among the ionotropic receptors that suffer the most desensitization upon prolonged exposure to their agonists. This is particularly true for the alpha7 subtype of nAChRs, although alpha3beta4 receptors also suffer quick desensitization. This study was planned to test the hypothesis that even after suffering desensitization, a given nAChR might still afford cell protection against a noxious stimulus. Of the many agonists developed for nAChRs, we selected the poorly desensitizing ligand dimethylphenylpiperazinium (DMPP) (Britt and Brenner, 1997) and the highly desensitizing agent epibatidine (EPB) (Marks et al., 1996). We have measured nAChR currents, catecholamine secretory responses, and changes of [Ca2+]c elicited by stimulation of nAChRs with DMPP or EPB. We have also investigated cytoprotection elicited by DMPP and EPB against the cytotoxic effects of veratridine in bovine chromaffin cells.

  10. 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.

  11. An ER-resident membrane protein complex regulates nicotinic acetylcholine receptor subunit composition at the synapse

    Science.gov (United States)

    Almedom, Ruta B; Liewald, Jana F; Hernando, Guillermina; Schultheis, Christian; Rayes, Diego; Pan, Jie; Schedletzky, Thorsten; Hutter, Harald; Bouzat, Cecilia; Gottschalk, Alexander

    2009-01-01

    Nicotinic acetylcholine receptors (nAChRs) are homo- or heteropentameric ligand-gated ion channels mediating excitatory neurotransmission and muscle activation. Regulation of nAChR subunit assembly and transfer of correctly assembled pentamers to the cell surface is only partially understood. Here, we characterize an ER transmembrane (TM) protein complex that influences nAChR cell-surface expression and functional properties in Caenorhabditis elegans muscle. Loss of either type I TM protein, NRA-2 or NRA-4 (nicotinic receptor associated), affects two different types of muscle nAChRs and causes in vivo resistance to cholinergic agonists. Sensitivity to subtype-specific agonists of these nAChRs is altered differently, as demonstrated by whole-cell voltage-clamp of dissected adult muscle, when applying exogenous agonists or after photo-evoked, channelrhodopsin-2 (ChR2) mediated acetylcholine (ACh) release, as well as in single-channel recordings in cultured embryonic muscle. These data suggest that nAChRs desensitize faster in nra-2 mutants. Cell-surface expression of different subunits of the ‘levamisole-sensitive' nAChR (L-AChR) is differentially affected in the absence of NRA-2 or NRA-4, suggesting that they control nAChR subunit composition or allow only certain receptor assemblies to leave the ER. PMID:19609303

  12. The nicotinic acetylcholine receptor and its prokaryotic homologues: Structure, conformational transitions & allosteric modulation.

    Science.gov (United States)

    Cecchini, Marco; Changeux, Jean-Pierre

    2015-09-01

    Pentameric ligand-gated ion channels (pLGICs) play a central role in intercellular communications in the nervous system by converting the binding of a chemical messenger - a neurotransmitter - into an ion flux through the postsynaptic membrane. Here, we present an overview of the most recent advances on the signal transduction mechanism boosted by X-ray crystallography of both prokaryotic and eukaryotic homologues of the nicotinic acetylcholine receptor (nAChR) in conjunction with time-resolved analyses based on single-channel electrophysiology and Molecular Dynamics simulations. The available data consistently point to a global mechanism of gating that involves a large reorganization of the receptor mediated by two distinct quaternary transitions: a global twisting and a radial expansion/contraction of the extracellular domain. These transitions profoundly modify the organization of the interface between subunits, which host several sites for orthosteric and allosteric modulatory ligands. The same mechanism may thus mediate both positive and negative allosteric modulations of pLGICs ligand binding at topographically distinct sites. The emerging picture of signal transduction is expected to pave the way to new pharmacological strategies for the development of allosteric modulators of nAChR and pLGICs in general. 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.

  13. The α4β2 nicotine acetylcholine receptor agonist ispronicline induces c-Fos expression in selective regions of the rat forebrain

    DEFF Research Database (Denmark)

    Jacobsen, Julie; Hansen, Henrik H; Kiss, Alexander;

    2012-01-01

    The dominant nicotine acetylcholine receptor (nAChR) subtype in the brain is the pentameric receptor containing both α4 and β2 subunits (α4β2). Due to the lack of selective agonists it has not been ruled out what neuronal circuits that are stimulated after systemic administration with nicotine. W...

  14. [[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

  15. Synthesis of analogues of (-)-cytisine for in vivo studies of nicotinic receptors using positron emission tomography.

    Science.gov (United States)

    Marrière, E; Rouden, J; Tadino, V; Lasne, M C

    2000-04-20

    [formula: see text] 9-Substituted analogues of (-)-cytisine were synthesized in high yields via palladium-mediated couplings of either 9-(-)-bromocytisine and organostannanes or 9-(-)-trimethylstannylcytisine and fluorobromobenzene. The protection of the amine with a nitroso group and the use of PdCl2(PPh3)2 to carry out the Stille reaction allowed the rapid synthesis of 9-(4'-[18F]fluorophenyl)cytisine (18F: t1/2 = 109.7 min), a new promising radioligand (radiochemical yield: 10% from [18F]KF, 150 min, four steps) for positron emission tomography studies of alpha 4 beta 2 nicotinic receptors.

  16. Identification of 9-fluoro substituted (-)-cytisine derivatives as ligands with high affinity for nicotinic receptors.

    Science.gov (United States)

    Houllier, Nicolas; Gopisetti, JaganMohan; Lestage, Pierre; Lasne, Marie-Claire; Rouden, Jacques

    2010-11-15

    (-)-9-Fluorocytisine, (-)-9-methylcytisine and (-)-9-trifluoromethylcytisine were synthesized from the natural product (-)-cytisine. 9-Methyl and 9-trifluoromethyl cytisines display a remarkable affinity at the α(4)β(2) nicotinic receptor subtype (0.2 nM) with a high selectivity versus the α(7) nAChR subtype. Comparison of the affinity values suggests that the size of the substituent at the 9 position of (-)-cytisine seems more important than electronic factors for efficient binding and selectivity at α(4)β(2) nAChRs.

  17. Neuronal nicotinic receptors as novel targets for inflammation and neuroprotection:mechanistic considerations and clinical relevance

    Institute of Scientific and Technical Information of China (English)

    Merouane BENGHEKIF

    2009-01-01

    A number of studies have confirmed the potential for neuronal nicotinic acetylcholine receptor (NNR)-mediated neuro- protection and, more recently, its anti-inflammatory effects. The mechanistic overlap between these pathways and the ubiquitous effects observed following diverse insults suggest that NNRs modulate fundamental pathways involved in cell survival. These results have wide-reaching implications for the design of experimental therapeutics that regulate inflamma- tory and anti-apoptotic responses through NNRs and represent an initial step toward understanding the benefits of novel therapeutic strategies for the management of central nervous system disorders that target neuronal survival and associated inflammatory processes.

  18. Effect of α₇ nicotinic acetylcholine receptor agonists and antagonists on motor function in mice.

    Science.gov (United States)

    Welch, Kevin D; Pfister, James A; Lima, Flavia G; Green, Benedict T; Gardner, Dale R

    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.

  19. Stimulation of α7 nicotinic acetylcholine receptor by nicotine increases suppressive capacity of naturally occurring CD4+CD25+ regulatory T cells in mice in vitro.

    Science.gov (United States)

    Wang, Da-wei; Zhou, Rong-bin; Yao, Yong-ming; Zhu, Xiao-mei; Yin, Yi-mei; Zhao, Guang-ju; Dong, Ning; Sheng, Zhi-yong

    2010-12-01

    α7 Nicotinic acetylcholine receptor (α7 nAChR) has been found in several non-neuronal cells and is described as an important regulator of cellular function. Naturally occurring CD4(+)CD25(+) regulatory T cells (Tregs) are essential for the active suppression of autoimmunity. The present study investigated whether naturally occurring Tregs expressed α7 nAChR and investigated the functionary role of this receptor in controlling suppressive activity of these cells. We found that CD4(+)CD25(+) Tregs from naive C57BL/6J mice positively expressed α7 nAChR, and its activation by nicotine enhanced the suppressive capacity of Tregs. Nicotine stimulation up-regulated the expression of cytotoxic T-lymphocyte-associated antigen (CTLA)-4 and forkhead/winged helix transcription factor p3 (Foxp3) on Tregs but had no effect on the production of interleukin (IL)-10 and transforming growth factor-β1 by Tregs. In the supernatants of CD4(+)CD25(+) Tregs/CD4(+)CD25(-) T-cell cocultures, we observed a decrease in the concentration of IL-2 in nicotine-stimulated groups, but nicotine stimulation had no effect on the ratio of IL-4/interferon (IFN)-γ, which partially represented T-cell polarization. The above-mentioned effects of nicotine were reversed by a selective α7 nAChR antagonist, α-bungarotoxin. In addition, the ratio of IL-4/IFN-γ was increased by treatment with α-bungarotoxin. We conclude that nicotine might increase Treg-mediated immune suppression of lymphocytes via α7 nAChR. The effect is related to the up-regulation of CTLA-4 as well as Foxp3 expression and decreased IL-2 secretion in CD4(+)CD25(+) Tregs/CD4(+)CD25(-) T-cell coculture supernatants. α7 nAChR seems to be a critical regulator for immunosuppressive function of CD4(+)CD25(+) Tregs.

  20. 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...... 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...

  1. Cannabinoid receptor ligands suppress memory-related effects of nicotine in the elevated plus maze test in mice.

    Science.gov (United States)

    Biala, Grazyna; Kruk, Marta

    2008-10-10

    The purpose of the experiments was to examine the memory-related effects of nicotine using the mouse elevated plus maze. It has been shown that the acute doses of nicotine (0.1 and 0.5 mg/kg) significantly decreased the time of transfer latency (TL2) on the retention trial, indicating that nicotine improved memory processes. Similarly, acute doses of the CB1 cannabinoid receptor antagonist AM 251 (0.5, 1, 1.5 and 3 mg/kg) significantly decreased TL2 values. WIN55,212-2, a non-selective CB cannabinoid receptor agonist, at any dose tested (0.25, 0.5 and 1 mg/kg), did not provoke any effect in this model. Moreover, the acute injection of both WIN55,212-2 (0.25 and 0.5 mg/kg) and AM 251 (0.25 mg/kg), prior to injections of nicotine (0.1 and 0.5 mg/kg), significantly prevented nicotine-induced memory improvement. The results of this study provide clear evidence that the endogenous cannabinoid system participates in the responses induced by nicotine on memory-related behaviour in mice.

  2. Dendritic spine density of prefrontal layer 6 pyramidal neurons in relation to apical dendrite sculpting by nicotinic acetylcholine receptors

    Directory of Open Access Journals (Sweden)

    Lily eKang

    2015-10-01

    Full Text Available Prefrontal layer 6 (L6 pyramidal neurons play an important role in the adult control of attention, facilitated by their strong activation by nicotinic acetylcholine receptors. These neurons in mouse association cortex are distinctive morphologically when compared to L6 neurons in primary cortical regions. Roughly equal proportions of the prefrontal L6 neurons have apical dendrites that are long (reaching to the pial surface versus short (terminating in the deep layers, as in primary cortical regions. This distinct prefrontal morphological pattern is established in the post-juvenile period and appears dependent on nicotinic receptors. Here, we examine dendritic spine densities in these two subgroups of prefrontal L6 pyramidal neurons under control conditions as well as after perturbation of nicotinic acetylcholine receptors. In control mice, the long neurons have significantly greater apical and basal dendritic spine density compared to the short neurons. Furthermore, manipulations of nicotinic receptors (chrna5 deletion or chronic developmental nicotine exposure have distinct effects on these two subgroups of L6 neurons: apical spine density is significantly reduced in long neurons, and basal spine density is significantly increased in short neurons. These changes appear dependent on the α5 nicotinic subunit encoded by chrna5. Overall, the two subgroups of prefrontal L6 neurons appear positioned to integrate information either across cortex (long neurons or within the deep layers (short neurons, and nicotinic perturbations differently alter spine density within each subgroup. Such changes have ramifications for adult executive function and possibly also for the morphological vulnerability of prefrontal cortex to subsequent stress exposure.

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

    Science.gov (United States)

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

    2006-06-06

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

  4. 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.......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....

  5. Antiamnestic effect of alpha7-nicotinic receptor agonist RJR-2403 in middle-aged ovariectomized rats with Alzheimer type dementia.

    Science.gov (United States)

    Sapronov, N S; Fedotova, Yu O; Kuznetsova, N N

    2006-12-01

    The effects of chronic combined treatment with alpha7-nicotinic cholinergic receptor agonist RJR-2403 (1.0 mg/kg intraperitoneally) or alpha7-nicotinic cholinergic receptor antagonist mecamylamine (1.0 mg/kg intraperitoneally) and 17beta-estradiol (0.5 microg per rat intramuscularly) for 10 days on passive avoidance retention were studied in middle-aged (15 months) ovariectomized rats with experimental Alzheimer type dementia. Chronic treatment with RJR-2403 and 17beta-estradiol had a pronounced antiamnestic effect under conditions of Alzheimer type dementia in middle-aged ovariectomized rats.

  6. Up-regulation of nicotinic acetylcholine receptors in menthol cigarette smokers.

    Science.gov (United States)

    Brody, Arthur L; Mukhin, Alexey G; La Charite, Jaime; Ta, Karen; Farahi, Judah; Sugar, Catherine A; Mamoun, Michael S; Vellios, Evan; Archie, Meena; Kozman, Maggie; Phuong, Jonathan; Arlorio, Franca; Mandelkern, Mark A

    2013-06-01

    One-third of smokers primarily use menthol cigarettes and usage of these cigarettes leads to elevated serum nicotine levels and more difficulty quitting in standard treatment programmes. Previous brain imaging studies demonstrate that smoking (without regard to cigarette type) leads to up-regulation of β(2)*-containing nicotinic acetylcholine receptors (nAChRs). We sought to determine if menthol cigarette usage results in greater nAChR up-regulation than non-menthol cigarette usage. Altogether, 114 participants (22 menthol cigarette smokers, 41 non-menthol cigarette smokers and 51 non-smokers) underwent positron emission tomography scanning using the α(4)β(2)* nAChR radioligand 2-[(18)F]fluoro-A-85380 (2-FA). In comparing menthol to non-menthol cigarette smokers, an overall test of 2-FA total volume of distribution values revealed a significant between-group difference, resulting from menthol smokers having 9-28% higher α(4)β(2)* nAChR densities than non-menthol smokers across regions. In comparing the entire group of smokers to non-smokers, an overall test revealed a significant between-group difference, resulting from smokers having higher α(4)β(2)* nAChR levels in all regions studied (36-42%) other than thalamus (3%). Study results demonstrate that menthol smokers have greater up-regulation of nAChRs than non-menthol smokers. This difference is presumably related to higher nicotine exposure in menthol smokers, although other mechanisms for menthol influencing receptor density are possible. These results provide additional information about the severity of menthol cigarette use and may help explain why these smokers have more trouble quitting in standard treatment programmes.

  7. Activation of nicotinic receptors uncouples a developmental timer from the molting timer in C. elegans.

    Science.gov (United States)

    Ruaud, Anne-Françoise; Bessereau, Jean-Louis

    2006-06-01

    C. elegans develops through four larval stages (L1 to L4) separated by molts. The identity of larval stages is mostly determined by stage-specific expression of heterochronic genes, which constitute an intrinsic genetic timer. However, extrinsic cues such as food availability or population density also modulate the developmental timing of C. elegans by mechanisms that remain largely unknown. To investigate a potential role of the nervous system in the temporal regulation of C. elegans development, we pharmacologically manipulated nicotinic neurotransmission, which represents a prominent signaling component in C. elegans nervous system. Exposure to the nicotinic agonist DMPP during post-embryonic development is lethal at the L2/L3 molt. Specifically, it delays cell divisions and differentiation during the L2 stage but does not affect the timing of the molt cycle, hence causing exposure of a defective L3 cuticle to the environment after the L2/L3 molt. Forcing development through a previously uncharacterized L2 diapause resynchronizes these events and suppresses DMPP-induced lethality. Nicotinic acetylcholine receptors (nAChRs) containing the UNC-63 subunit are required, probably in neurons, to trigger the action of DMPP. Using a forward genetic screen, we further demonstrated that the nuclear hormone receptor (NHR) DAF-12 is necessary to implement the developmental effects of DMPP. Therefore, a novel neuroendocrine pathway involving nAChRs and the NHR DAF-12 can control the speed of stage-specific developmental events in C. elegans. Activation of DMPP-sensitive nAChRs during the second larval stage uncouples a molting timer and a developmental timer, thus causing a heterochronic phenotype that is lethal at the subsequent molt.

  8. 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 are 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. PMID:24530453

  9. Autoradiographic localization of nicotinic acetylcholine receptors in the brain of the zebra finch (Poephila guttata)

    Energy Technology Data Exchange (ETDEWEB)

    Watson, J.T.; Adkins-Regan, E.; Whiting, P.; Lindstrom, J.M.; Podleski, T.R.

    1988-08-08

    We have localized nicotinic acetylcholine receptors in the zebra finch brain by using three 125I-labelled ligands: alpha bungarotoxin and two monoclonal antibodies to neuronal nicotinic receptors. Unfixed brains from intact adult male and female zebra finches were prepared for in vitro autoradiography. Low-resolution film autoradiograms and high-resolution emulsion autoradiograms were prepared for each of the three ligands. The major brain structures that bind all three of the ligands are hippocampus; hyperstriatum dorsalis; hyperstriatum ventralis; nucleus lentiformis mesencephali; nucleus pretectalis, some layers of the optic tectum; nucleus mesencephalicus lateralis; pars dorsalis; locus ceruleus; and all cranial motor nuclei except nucleus nervi hypoglossi. The major structures labelled only by (125I)-alpha bungarotoxin binding included hyperstriatum accessorium and the nuclei: preopticus medialis, medialis hypothalami posterioris, semilunaris, olivarius inferior, and the periventricular organ. Of the song control nuclei, nucleus magnocellularis of the anterior neostriatum; hyperstriatum ventralis, pars caudalis; nucleus intercollicularis; and nucleus hypoglossus were labelled. The binding patterns of the two antibodies were similar to one another but not identical. Both labelled nucleus spiriformis lateralis and nucleus geniculatus lateralis, pars ventralis especially heavily and also labelled the nucleus habenula medialis; nucleus subpretectalis; nucleus isthmi, pars magnocellularis; nucleus reticularis gigantocellularis; nucleus reticularis lateralis; nucleus tractus solitarii; nucleus vestibularis dorsolateralis; nucleus vestibularis lateralis; nucleus descendens nervi trigemini; and the deep cerebellar nuclei.

  10. Effect of muscarinic and nicotinic receptor antagonism on rat gastric motor activity.

    Science.gov (United States)

    Janssen, Pieter; Karlsson, Lisa K C; Nielsen, Maria Astin; Gillberg, Per-Göran; Hultin, Leif

    2010-01-01

    Our aim was to investigate whether muscarinic and nicotinic receptors mediate nitric oxide release during motor events in the rat stomach. Isolated rat stomach volume changes were monitored in an organ bath setup with an intragastric balloon coupled to a barostat and studied in basal conditions and during electrical vagal stimulation (EVS). In conscious rats, the intragastric pressure (IGP) was measured during test meal infusion. In the presence of N(G)-nitro-L-arginine methyl ester (L-NAME; 0.1 mmol/l), EVS induced significant gastric contractions (mean +/- SEM = 0.27 +/- 0.04 ml; n = 6) that could be blocked by atropine (3 micromol/l) and hexamethonium (0.1 mmol/l). In the presence of atropine and/or hexamethonium, EVS-induced relaxations could not be blocked by L-NAME, while exogenous nitric oxide could still relax the stomach. In conscious rats, atropine (1 mg kg(-1)) initially decreased IGP, while during further distension it increased IGP. In the presence of L-NAME (30 mg kg(-1)) atropine consistently decreased IGP. L-NAME alone significantly increased IGP during the test meal infusion, but this effect was reduced in the presence of atropine. These findings indicate a role for nicotinic and muscarinic receptors in the vagal-stimulation-induced activation of nitrergic nerves in the rat stomach. Copyright 2010 S. Karger AG, Basel.

  11. Expression of nicotinic acetylcholine receptor subunits from parasitic nematodes in Caenorhabditis elegans.

    Science.gov (United States)

    Sloan, Megan A; Reaves, Barbara J; Maclean, Mary J; Storey, Bob E; Wolstenholme, Adrian J

    2015-11-01

    The levamisole-sensitive nicotinic acetylcholine receptor present at nematode neuromuscular junctions is composed of multiple different subunits, with the exact composition varying between species. We tested the ability of two well-conserved nicotinic receptor subunits, UNC-38 and UNC-29, from Haemonchus contortus and Ascaris suum to rescue the levamisole-resistance and locomotion defects of Caenorhabditis elegans strains with null deletion mutations in the unc-38 and unc-29 genes. The parasite cDNAs were cloned downstream of the relevant C. elegans promoters and introduced into the mutant strains via biolistic transformation. The UNC-38 subunit of H. contortus was able to completely rescue both the locomotion defects and levamisole resistance of the null deletion mutant VC2937 (ok2896), but no C. elegans expressing the A. suum UNC-38 could be detected. The H. contortus UNC-29.1 subunit partially rescued the levamisole resistance of a C. elegans null mutation in unc-29 VC1944 (ok2450), but did cause increased motility in a thrashing assay. In contrast, only a single line of worms containing the A. suum UNC-29 subunit showed a partial rescue of levamisole resistance, with no effect on thrashing.

  12. Modelling and simulation of ion channels: applications to the nicotinic acetylcholine receptor.

    Science.gov (United States)

    Sansom, M S; Adcock, C; Smith, G R

    1998-01-01

    Molecular dynamics simulations with experimentally derived restraints have been used to develop atomic models of M2 helix bundles forming the pore-lining domains of the nicotinic acetylcholine receptor and related ligand-gated ion channels. M2 helix bundles have been used in microscopic simulations of the dynamics and energetics of water and ions within an ion channel. Translational and rotational motion of water are restricted within the pore, and water dipoles are aligned relative to the pore axis by the surrounding helix dipoles. Potential energy profiles for translation of a Na+ ion along the pore suggest that the protein and water components of the interaction energy exert an opposing effect on the ion, resulting in a relatively flat profile which favors cation permeation. Empirical conductance calculations based on a pore radius profile suggest that the M2 helix model is consistent with a single channel conductance of ca. 50 pS. Continuum electrostatics calculations indicate that a ring of glutamate residues at the cytoplasmic mouth of the alpha 7 nicotinic receptor M2 helix bundle may not be fully ionized. A simplified model of the remainder of the channel protein when added to the M2 helix bundle plays a significant role in enhancing the ion selectivity of the channel.

  13. Quinuclidine compounds differently act as agonists of Kenyon cell nicotinic acetylcholine receptors and induced distinct effect on insect ganglionic depolarizations.

    Science.gov (United States)

    Mathé-Allainmat, Monique; Swale, Daniel; Leray, Xavier; Benzidane, Yassine; Lebreton, Jacques; Bloomquist, Jeffrey R; Thany, Steeve H

    2013-12-01

    We have recently demonstrated that a new quinuclidine benzamide compound named LMA10203 acted as an agonist of insect nicotinic acetylcholine receptors. Its specific pharmacological profile on cockroach dorsal unpaired median neurons (DUM) helped to identify alpha-bungarotoxin-insensitive nAChR2 receptors. In the present study, we tested its effect on cockroach Kenyon cells. We found that it induced an inward current demonstrating that it bounds to nicotinic acetylcholine receptors expressed on Kenyon cells. Interestingly, LMA10203-induced currents were completely blocked by the nicotinic antagonist α-bungarotoxin. We suggested that LMA10203 effect occurred through the activation of α-bungarotoxin-sensitive receptors and did not involve α-bungarotoxin-insensitive nAChR2, previously identified in DUM neurons. In addition, we have synthesized two new compounds, LMA10210 and LMA10211, and compared their effects on Kenyon cells. These compounds were members of the 3-quinuclidinyl benzamide or benzoate families. Interestingly, 1 mM LMA10210 was not able to induce an inward current on Kenyon cells compared to LMA10211. Similarly, we did not find any significant effect of LMA10210 on cockroach ganglionic depolarization, whereas these three compounds were able to induce an effect on the central nervous system of the third instar M. domestica larvae. Our data suggested that these three compounds could bind to distinct cockroach nicotinic acetylcholine receptors.

  14. 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.

  15. The Protective Effect of Alpha 7 Nicotinic Acetylcholine Receptor Activation on Critical Illness and Its Mechanism

    Science.gov (United States)

    REN, Chao; TONG, Ya-lin; LI, Jun-cong; LU, Zhong-qiu; YAO, Yong-ming

    2017-01-01

    Critical illnesses and injuries are recognized as major threats to human health, and they are usually accompanied by uncontrolled inflammation and dysfunction of immune response. The alpha 7 nicotinic acetylcholine receptor (α7nAchR), which is a primary receptor of cholinergic anti-inflammatory pathway (CAP), exhibits great benefits for critical ill conditions. It is composed of 5 identical α7 subunits that form a central pore with high permeability for calcium. This putative structure is closely associated with its functional states. Activated α7nAChR exhibits extensive anti-inflammatory and immune modulatory reactions, including lowered pro-inflammatory cytokines levels, decreased expressions of chemokines as well as adhesion molecules, and altered differentiation and activation of immune cells, which are important in maintaining immune homeostasis. Well understanding of the effects and mechanisms of α7nAChR will be of great value in exploring effective targets for treating critical diseases. PMID:28123345

  16. High Throughput Random Mutagenesis and Single Molecule Real Time Sequencing of the Muscle Nicotinic Acetylcholine Receptor

    Science.gov (United States)

    Groot-Kormelink, Paul J.; Ferrand, Sandrine; Kelley, Nicholas; Bill, Anke; Freuler, Felix; Imbert, Pierre-Eloi; Marelli, Anthony; Gerwin, Nicole; Sivilotti, Lucia G.; Miraglia, Loren; Orth, Anthony P.; Oakeley, Edward J.; Schopfer, Ulrich; Siehler, Sandra

    2016-01-01

    High throughput random mutagenesis is a powerful tool to identify which residues are important for the function of a protein, and gain insight into its structure-function relation. The human muscle nicotinic acetylcholine receptor was used to test whether this technique previously used for monomeric receptors can be applied to a pentameric ligand-gated ion channel. A mutant library for the α1 subunit of the channel was generated by error-prone PCR, and full length sequences of all 2816 mutants were retrieved using single molecule real time sequencing. Each α1 mutant was co-transfected with wildtype β1, δ, and ε subunits, and the channel function characterized by an ion flux assay. To test whether the strategy could map the structure-function relation of this receptor, we attempted to identify mutations that conferred resistance to competitive antagonists. Mutant hits were defined as receptors that responded to the nicotinic agonist epibatidine, but were not inhibited by either α-bungarotoxin or tubocurarine. Eight α1 subunit mutant hits were identified, six of which contained mutations at position Y233 or V275 in the transmembrane domain. Three single point mutations (Y233N, Y233H, and V275M) were studied further, and found to enhance the potencies of five channel agonists tested. This suggests that the mutations made the channel resistant to the antagonists, not by impairing antagonist binding, but rather by producing a gain-of-function phenotype, e.g. increased agonist sensitivity. Our data show that random high throughput mutagenesis is applicable to multimeric proteins to discover novel functional mutants, and outlines the benefits of using single molecule real time sequencing with regards to quality control of the mutant library as well as downstream mutant data interpretation. PMID:27649498

  17. 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......AChR in patients with bipolar disorder....

  18. 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.

  19. Carbamoylcholine analogs as nicotinic acetylcholine receptor agonists--structural modifications of 3-(dimethylamino)butyl dimethylcarbamate (DMABC)

    DEFF Research Database (Denmark)

    Hansen, Camilla Petrycer; Jensen, Anders Asbjørn; Balle, Thomas

    2009-01-01

    Compounds based on the 3-(dimethylamino)butyl dimethylcarbamate (DMABC) scaffold were synthesized and pharmacologically characterized at the alpha(4)beta(2), alpha(3)beta(4,) alpha(4)beta(4) and alpha(7) neuronal nicotinic acetylcholine receptors (nAChRs). The carbamate functionality and a small...

  20. 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...

  1. In pursuit of alpha4beta2 nicotinic receptor partial agonists for smoking cessation: carbon analogs of (-)-cytisine.

    Science.gov (United States)

    Coe, Jotham W; Vetelino, Michael G; Bashore, Crystal G; Wirtz, Michael C; Brooks, Paige R; Arnold, Eric P; Lebel, Lorraine A; Fox, Carol B; Sands, Steven B; Davis, Thomas I; Schulz, David W; Rollema, Hans; Tingley, F David; O'Neill, Brian T

    2005-06-15

    The preparation and biological activity of analogs of (-)-cytisine, an alpha4beta2 nicotinic receptor partial agonist, are discussed. All-carbon-containing phenyl ring replacements of the pyridone ring system, generated via Heck cyclization protocols, exhibited weaker affinity and lower efficacy partial agonist profiles relative to (-)-cytisine. In vivo, selected compounds exhibit lower efficacy partial agonist profiles than that of (-)-cytisine.

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

    Science.gov (United States)

    Vulfius, Catherine A; Kasheverov, Igor E; Starkov, Vladislav G; Osipov, Alexey V; Andreeva, Tatyana V; Filkin, Sergey Yu; Gorbacheva, Elena V; Astashev, Maxim E; Tsetlin, Victor I; Utkin, Yuri N

    2014-01-01

    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.

  3. 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.

  4. Structure-activity relationships for the irreversible blockade of nicotinic receptor agonist sites by lophotoxin and congeneric diterpene lactones

    Energy Technology Data Exchange (ETDEWEB)

    Culver, P.; Burch, M.; Potenza, C.; Wasserman, L.; Fenical, W.; Taylor, P.

    1985-11-01

    Lophotoxin, a diterpene lactone paralytic toxin from gorgonian corals of the genus Lophogorgia, inhibits ( SVI)-alpha-toxin binding to surface nicotinic receptors of BC3H-1 cells by irreversible occupation of the primary agonist sites. In contrast, receptor-bearing membrane fragments or detergent-solubilized receptors prepared from BC3H-1 cells are not susceptible to lophotoxin block. Thus, lophotoxin inhibition requires intact cells. However, when intact cells were incubated with lophotoxin, subsequent membrane-fragment preparation or detergent solubilization of the receptors did not diminish lophotoxin occupation of ( SVI)-alpha-toxin-binding sites, indicating that lophotoxin binds very tightly to nicotinic receptors. These studies further demonstrate that both surface and nonsurface nicotinic receptors of BC3H-1 cells are susceptible to irreversible occupation by lophotoxin, indicating that the lipophilic toxin freely permeates intact cells. The authors also examined several structural analogs of lophotoxin, one of which was equipotent with lophotoxin for inhibition of ( SVI)-alpha-toxin binding to intact cells and, notably, also blocked alpha-toxin binding to detergent-extracted receptor.

  5. Perinatal hypoxia-ischemia reduces α 7 nicotinic receptor expression and selective α 7 nicotinic receptor stimulation suppresses inflammation and promotes microglial Mox phenotype.

    Science.gov (United States)

    Hua, Sansan; Ek, C Joakim; Mallard, Carina; Johansson, Maria E

    2014-01-01

    Inflammation plays a central role in neonatal brain injury. During brain inflammation the resident macrophages of the brain, the microglia cells, are rapidly activated. In the periphery, α 7 nicotinic acetylcholine receptors ( α 7R) present on macrophages can regulate inflammation by suppressing cytokine release. In the current study we investigated α 7R expression in neonatal mice after hypoxia-ischemia (HI). We further examined possible anti-inflammatory role of α 7R stimulation in vitro and microglia polarization after α 7R agonist treatment. Real-time PCR analysis showed a 33% reduction in α 7R expression 72 h after HI. Stimulation of primary microglial cells with LPS in combination with increasing doses of the selective α 7R agonist AR-R 17779 significantly attenuated TNF α release and increased α 7R transcript in microglial cells. Gene expression of M1 markers CD86 and iNOS, as well as M2 marker CD206 was not influenced by LPS and/or α 7R agonist treatment. Further, Mox markers heme oxygenase (Hmox1) and sulforedoxin-1 (Srx1) were significantly increased, suggesting a polarization towards the Mox phenotype after α 7R stimulation. Thus, our data suggest a role for the α 7R also in the neonatal brain and support the anti-inflammatory role of α 7R in microglia, suggesting that α 7R stimulation could enhance the polarization towards a reparative Mox phenotype.

  6. Perinatal Hypoxia-Ischemia Reduces α7 Nicotinic Receptor Expression and Selective α7 Nicotinic Receptor Stimulation Suppresses Inflammation and Promotes Microglial Mox Phenotype

    Directory of Open Access Journals (Sweden)

    Sansan Hua

    2014-01-01

    Full Text Available Inflammation plays a central role in neonatal brain injury. During brain inflammation the resident macrophages of the brain, the microglia cells, are rapidly activated. In the periphery, α7 nicotinic acetylcholine receptors (α7R present on macrophages can regulate inflammation by suppressing cytokine release. In the current study we investigated α7R expression in neonatal mice after hypoxia-ischemia (HI. We further examined possible anti-inflammatory role of α7R stimulation in vitro and microglia polarization after α7R agonist treatment. Real-time PCR analysis showed a 33% reduction in α7R expression 72 h after HI. Stimulation of primary microglial cells with LPS in combination with increasing doses of the selective α7R agonist AR-R 17779 significantly attenuated TNFα release and increased α7R transcript in microglial cells. Gene expression of M1 markers CD86 and iNOS, as well as M2 marker CD206 was not influenced by LPS and/or α7R agonist treatment. Further, Mox markers heme oxygenase (Hmox1 and sulforedoxin-1 (Srx1 were significantly increased, suggesting a polarization towards the Mox phenotype after α7R stimulation. Thus, our data suggest a role for the α7R also in the neonatal brain and support the anti-inflammatory role of α7R in microglia, suggesting that α7R stimulation could enhance the polarization towards a reparative Mox phenotype.

  7. 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.

  8. Direct actions of organophosphate anticholinesterases on nicotinic and muscarinic acetylcholine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Bakry, N.M.; el-Rashidy, A.H.; Eldefrawi, A.T.; Eldefrawi, M.E.

    Four nerve agents and one therapeutic organophosphate (OP) anticholinesterase (anti-ChE) bind to acetylcholine (ACh) receptors, inhibit or modulate binding of radioactive ligands to these receptors, and modify events regulated by them. The affinity of nicotinic (n) ACh receptors of Torpedo electric organs and most muscarinic (m) ACh receptors of rat brain and N1E-115 neuroblastoma cultures for the OP compounds was usually two to three orders of magnitude lower than concentrations required to inhibit 50% (IC-50) of ACh-esterase activity. However, a small population of m-ACh receptors had an affinity as high as that of ACh-esterase for the OP compound. This population is identified by its high-affinity (3H)-cis-methyldioxolane ((3H)-CD) binding. Although sarin, soman, and tabun had no effect, (O-ethyl S(2-(diisopropylamino)ethyl)) methyl phosphonothionate (VX) and echothiophate inhibited competitively the binding of (3H)-quinuclidinyl benzilate ((3H)-QNB) and (3H)-pirenzepine ((3H)-PZ) to m-ACh receptors. However, VX was more potent than echothiophate in inhibiting this binding and 50-fold more potent in inhibiting carbamylcholine (carb)-stimulated (3H)-cGMP synthesis in N1E-115 neuroblastoma cells--both acting as m receptor antagonist. All five OPs inhibited (3H)-CD binding, with IC-50s of 3, 10, 40, 100, and 800 nM for VX, soman, sarin, echothiophate, and tabun, respectively. The OP anticholinesterases also bound to allosteric sites on the n-ACh receptor (identified by inhibition of (3H)-phencyclidine binding), but some bound as well to the receptor's recognition site (identified by inhibition of (125I)-alpha-bungarotoxin binding). Soman and echothiophate in micromolar concentrations acted as partial agonists of the n-ACh receptor and induced receptor desensitization. On the other hand, VX acted as an open channel blocker of the activated receptor and also enhanced receptor desensitization.

  9. Association of single nucleotide polymorphisms of nicotinic acetylcholine receptor subunits with cervical neoplasia

    Science.gov (United States)

    Calleja-Macias, Itzel; Osann, Kathryn; Remedios-Chan, Mariana; Barrera-Saldana, Hugo A.; Illades-Aguiar, Berenice; Anton-Culver, Hoda; Chikova, Anna K.; Grando, Sergei A.; Bernard, Hans-Ulrich

    2014-01-01

    Aims Cholinergic signaling, particularly in response to non-physiological ligands like nicotine, stimulates carcinogenesis of a variety of tissue types including epithelia of the cervix uteri. Cholinergic signaling is mediated by nicotinic acetylcholine receptors (nAChRs), which are pentamers formed by subsets of 16 nAChR subunits. Recent literature suggests that single nucleotide polymorphisms (SNPs) of some of these subunits, notably alpha5, are risk factors for developing lung cancer in smokers as well as in non-smokers. Main methods We have studied the prevalence of four SNPs in the alpha5, alpha9, and beta1 subunits, which are expressed in cervical cells, in 456 patients with cervical cancers, precursor lesions, and healthy controls from two cohorts in Mexico. Key findings A SNP in the alpha9 subunit, the G allele of rs10009228 (alpha9, A>G) shows a significant trend in the combined cohort, indicating that this allele constitutes a risk factor for neoplastic progression. The A allele of the SNP rs16969968 (alpha5, G>A), which correlates with the development of lung cancer, shows a non-significant trend to be associated with cervical lesions. Two other SNPs, rs55633891 (alpha9, C>T) and rs17856697 (beta1, A>G), did not exhibit a significant trend. Significance Our study points to a potential risk factor of cervical carcinogenesis with importance for DNA diagnosis and as a target for intervention. PMID:22406075

  10. Positive modulators of the α7 nicotinic receptor against neuroinflammation and cognitive impairment in Alzheimer's disease.

    Science.gov (United States)

    Echeverria, Valentina; Yarkov, Alex; Aliev, Gjumrakch

    2016-09-01

    Evidence so far indicates that therapies targeting a single aspect of Alzheimer's disease (AD) have no sufficient efficacy in diminishing long-term the progression of AD. Neuroinflammation is an early event during the development of the disease and it is thought to exacerbate the abnormal aggregation of the amyloid beta peptide (Aβ) and the microtubule associated protein Tau. Inhibition of gliosis is considered fundamental to reduce neuroinflammation, oxidative stress, apoptosis and synaptic dysfunction driving the progression of AD. Drugs that are able to target more than one aspect of the pathology may have higher chances of success. Modulators of α7 nicotinic acetylcholine receptors (α7nAChRs) such as nicotine and some of its derivatives have this potential because of their anti-inflammatory, anti-apoptotic, pro-cognitive and anti-protein aggregation effects. However, the rapid desensitization of α7nAChRs is considered an important factor limiting its potential therapeutic use. In here, in light of current evidence, the objective of this review is to discuss the advantages and potential therapeutic value of positive allosteric modulators (PAMs) of the nAChRs in halting or delaying the progression of AD by diminishing neuroinflammation, abnormal protein aggregation and synaptic dysfunction.

  11. The influence of allosteric modulators and transmembrane mutations on desensitisation and activation of α7 nicotinic acetylcholine receptors.

    OpenAIRE

    Chatzidaki, A.; D Oyley, J. M.; Gill-Thind, J. K.; Sheppard, T. D.; Millar, N S

    2015-01-01

    Acetylcholine activates nicotinic acetylcholine receptors (nAChRs) by binding at an extracellular orthosteric site. Previous studies have described several positive allosteric modulators (PAMs) that are selective for homomeric α7 nAChRs. These include type I PAMs, which exert little or no effect on the rate of receptor desensitisation, and type II PAMs, which cause a dramatic loss of agonist-induced desensitisation. Here we report evidence that transmembrane mutations in α7 nAChRs have divers...

  12. The influence of allosteric modulators and transmembrane mutations on desensitisation and activation of α7 nicotinic acetylcholine receptors

    OpenAIRE

    Chatzidaki, Anna; D'Oyley, Jarryl M; Gill-Thind, JasKiran K.; Sheppard, Tom D; Millar, Neil S.

    2015-01-01

    Acetylcholine activates nicotinic acetylcholine receptors (nAChRs) by binding at an extracellular orthosteric site. Previous studies have described several positive allosteric modulators (PAMs) that are selective for homomeric α7 nAChRs. These include type I PAMs, which exert little or no effect on the rate of receptor desensitisation, and type II PAMs, which cause a dramatic loss of agonist-induced desensitisation. Here we report evidence that transmembrane mutations in α7 nAChRs have divers...

  13. 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.

  14. A novel physiological property of snake bradykinin-potentiating peptides-reversion of MK-801 inhibition of nicotinic acetylcholine receptors.

    Science.gov (United States)

    Nery, Arthur A; Trujillo, Cleber A; Lameu, Claudiana; Konno, Katsuhiro; Oliveira, Vitor; Camargo, Antonio C M; Ulrich, Henning; Hayashi, Mirian A F

    2008-10-01

    The first naturally occurring angiotensin-converting enzyme (ACE) inhibitors described are pyroglutamyl proline-rich oligopeptides, found in the venom of the viper Bothrops jararaca, and named as bradykinin-potentiating peptides (BPPs). Biochemical and pharmacological properties of these peptides were essential for the development of Captopril, the first active site-directed inhibitor of ACE, currently used for the treatment of human hypertension. However, a number of data have suggested that the pharmacological activity of BPPs could not only be explained by their inhibitory action on enzymatic activity of somatic ACE. In fact, we showed recently that the strong and long-lasting anti-hypertensive effect of BPP-10c [pheochromocytoma cell line, which following induction to neuronal differentiation expresses most of the nicotinic receptor subtypes. BPP-10c did not induce receptor-mediated ion flux, nor potentiated carbamoylcholine-provoked receptor activity as determined by whole-cell recording. This peptide, however, alleviated MK-801-induced inhibition of nicotinic acetylcholine receptor activity. Although more data are needed for understanding the mechanism of the BPP-10c effect on nicotinic receptor activity and its relationship with the anti-hypertensive activity, this work reveals possible therapeutic applications for BPP-10c in establishing normal acetylcholine receptor activity.

  15. Nicotinic α7 receptor activation selectively potentiates the function of NMDA receptors in glutamatergic terminals of the nucleus accumbens

    Directory of Open Access Journals (Sweden)

    Stefania eZappettini

    2014-10-01

    Full Text Available We here provide functional and immunocytochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs and N-methyl-D-aspartic acid receptors (NMDARs in glutamatergic terminals of the nucleus accumbens (NAc. Immunocytochemical studies showed that a significant percentage of NAc terminals were glutamatergic and possessed GluN1 and α7-containing nAChR. A short-term pre-exposure of synaptosomes to nicotine (30 µM or choline (1 mM caused a significant potentiation of the 100 µM NMDA-evoked [3H]D-aspartate ([3H]D-Asp outflow, which was prevented by α-bungarotoxin (100 nM. The pre-exposure to nicotine (100 µM or choline (1 mM also enhanced the NMDA-induced cytosolic free calcium levels, as measured by FURA-2 fluorescence imaging in individual NAc terminals, an effect also prevented by α-bungarotoxin. Pre-exposure to the α4-nAChR agonists 5IA85380 (10 nM or RJR2429 (1 µM did not modify NMDA-evoked ([3H]D-Asp outflow and calcium transients. The NMDA-evoked ([3H]D-Asp overflow was partially antagonized by the NMDAR antagonists MK801, D-AP5, 5,7-DCKA and R(-CPP and unaffected by the GluN2B-NMDAR antagonists Ro256981 and ifenprodil. Notably, pre-treatment with choline increased GluN2A biotin-tagged proteins. In conclusion, our results show that the GluN2A-NMDA receptor function can be positively regulated in NAc terminals in response to a brief incubation with α7 but not α4 nAChRs agonists. This might be a general feature in different brain areas since a similar nAChR-mediated bolstering of NMDA-induced ([3H]D-Aspoverflow was also observed in hippocampal synaptosomes.

  16. 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 to t...

  17. 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...

  18. Genetic variation in mu-opioid-receptor-interacting proteins and smoking cessation in a nicotine replacement therapy trial.

    Science.gov (United States)

    Ray, Riju; Jepson, Christopher; Wileyto, E Paul; Dahl, John P; Patterson, Freda; Rukstalis, Margaret; Pinto, Angela; Berrettini, Wade; Lerman, Caryn

    2007-11-01

    Extending a previous finding of an association between functional genetic variation in the mu-opioid receptor gene and response to nicotine replacement therapy, we explored the role of genetic variants in two genes encoding mu-opioid-receptor-interacting proteins, namely ARRB2 and HINT1. Participants were 374 smokers treated for nicotine dependence with either transdermal nicotine or nicotine nasal spray for 8 weeks in an open-label randomized trial. In a logistic regression model controlling for OPRM1 genotype, treatment type, and other covariates, we found no significant main effect of ARRB2 genotype on abstinence at either end of treatment or 6-month follow-up. Participants with the HINT1 TT genotype had significantly higher abstinence rates at 6-month follow-up, but this may not be a pharmacogenetic effect, given that the participants were drug free during this time. Haplotype analysis did not reveal any significant associations for either gene. We found an interaction of ARRB2 and OPRM1 genotype on abstinence at 6 months that approached significance; however, interpretation of this finding is limited by the small number of participants with the minor alleles for both genes. Although these data do not provide support for the role of genetic variation in these mu-opioid-receptor-interacting proteins and smoking cessation, further exploration of opioid pathway genes in larger prospective pharmacogenetic trials may be warranted.

  19. alpha-conotoxin EpI, a novel sulfated peptide from Conus episcopatus that selectively targets neuronal nicotinic acetylcholine receptors.

    Science.gov (United States)

    Loughnan, M; Bond, T; Atkins, A; Cuevas, J; Adams, D J; Broxton, N M; Livett, B G; Down, J G; Jones, A; Alewood, P F; Lewis, R J

    1998-06-19

    We have isolated and characterized alpha-conotoxin EpI, a novel sulfated peptide from the venom of the molluscivorous snail, Conus episcopatus. The peptide was classified as an alpha-conotoxin based on sequence, disulfide connectivity, and pharmacological target. EpI has homology to sequences of previously described alpha-conotoxins, particularly PnIA, PnIB, and ImI. However, EpI differs from previously reported conotoxins in that it has a sulfotyrosine residue, identified by amino acid analysis and mass spectrometry. Native EpI was shown to coelute with synthetic EpI. The peptide sequence is consistent with most, but not all, recognized criteria for predicting tyrosine sulfation sites in proteins and peptides. The activities of synthetic EpI and its unsulfated analogue [Tyr15]EpI were similar. Both peptides caused competitive inhibition of nicotine action on bovine adrenal chromaffin cells (neuronal nicotinic ACh receptors) but had no effect on the rat phrenic nerve-diaphragm (muscle nicotinic ACh receptors). Both EpI and [Tyr15]EpI partly inhibited acetylcholine-evoked currents in isolated parasympathetic neurons of rat intracardiac ganglia. These results indicate that EpI and [Tyr15]EpI selectively inhibit alpha3beta2 and alpha3 beta4 nicotinic acetylcholine receptors.

  20. Adolescent exposure to nicotine and/or the cannabinoid agonist CP 55,940 induces gender-dependent long-lasting memory impairments and changes in brain nicotinic and CB(1) cannabinoid receptors.

    Science.gov (United States)

    Mateos, B; Borcel, E; Loriga, R; Luesu, W; Bini, V; Llorente, R; Castelli, M P; Viveros, M-P

    2011-12-01

    We have analysed the long-term effects of adolescent (postnatal day 28-43) exposure of male and female rats to nicotine (NIC, 1.4 mg/kg/day) and/or the cannabinoid agonist CP 55,940 (CP, 0.4 mg/kg/day) on the following parameters measured in the adulthood: (1) the memory ability evaluated in the object location task (OL) and in the novel object test (NOT); (2) the anxiety-like behaviour in the elevated plus maze; and (3) nicotinic and CB(1) cannabinoid receptors in cingulated cortex and hippocampus. In the OL, all pharmacological treatments induced significant decreases in the DI of females, whereas no significant effects were found among males. In the NOT, NIC-treated females showed a significantly reduced DI, whereas the effect of the cannabinoid agonist (a decrease in the DI) was only significant in males. The anxiety-related behaviour was not changed by any drug. Both, nicotine and cannabinoid treatments induced a long-lasting increase in CB(1) receptor activity (CP-stimulated GTPγS binding) in male rats, and the nicotine treatment also induced a decrease in nicotinic receptor density in the prefrontal cortex of females. The results show gender-dependent harmful effects of both drugs and long-lasting changes in CB(1) and nicotinic receptors.

  1. Design and synthesis of isoxazole containing bioisosteres of epibatidine as potent nicotinic acetylcholine receptor agonists.

    Science.gov (United States)

    Singh, S; Avor, K S; Pouw, B; Seale, T W; Basmadjian, G P

    1999-10-01

    An efficient synthesis of isoxazole containing isosteres of epibatidine is described. The synthesis proceeded from N-tert-butoxycarbonyl (Boc)-exo-2-(methoxycarbonyl)-7-azabicyclo[2.2.1]heptane (9). Compound 9 was reacted with the dilithium salt of an appropriately substituted oxime in tetrahydrofuran (THF). Cyclodehydration of the resultant beta-keto oxime and deprotection of the N-Boc group in 5 N aqueous HCl afforded the isoxazole containing isosteres of epibatidine (6-8). The binding affinities of these compounds were determined at the nicotinic acetylcholine receptor for the displacement of [3H]cystisine. The unsubstituted isoxazole containing isostere (6) showed the lower binding potency compared to the 3'-methylisoxazole isostere (7). Substitution with a phenyl group at the 3'-position of the isoxazole significantly reduced the binding potency. The in vivo toxicological studies of these analogs were also performed. The LD50 of the analogs ranged in the order: Me > H > Ph.

  2. 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...... in patients with schizophrenia. In addition, PCP increased the basal mRNA expression in the PFC of the activity-regulated cytoskeleton-associated protein (Arc), a molecule involved in synaptic plasticity. These molecular changes produced by PCP were accompanied by a behavioral impairment as determined...... in a modified Y-maze test. Polymorphisms in the alpha(7) nicotinic acetylcholine receptor (nAChR) gene have been linked to schizophrenia. Here we demonstrate that acute administration of the selective alpha(7) nAChR partial agonist SSR180711 dose-dependently reversed the behavioral impairment induced by PCP...

  3. Relationship between Polymorphism of Nicotinic Acetylcholine Receptor Gene CHRNA3 and Susceptibility of Lung Cancer

    Institute of Scientific and Technical Information of China (English)

    Shen Bo; Shi Meiqi; Mei Jinfeng; Hong Zhuan; Cao Guochun; Lu Jianwei; Feng Jifeng

    2013-01-01

    Objective:To investigate the relationship between polymorphism of nicotinic acetylcholine receptor gene CHRNA3 and susceptibility of lung cancer. Methods:Sixty hundred patients with lung cancer and 600 healthy people were respectively selected. TaqMan-MGB probe technique was applied to detect rs3743073 (T > G) genotypes at SNPs site on CHRNA3. The difference of genotype distribution among groups was compared, and its relationship with lung cancer was also investigated. Results:There was statistical signiifcance regarding the distributions of CHRNA3 rs3743073 (T>G) genotype and allele frequencies in patients with lung cancer and healthy people (P Conclusion:The risk of developing lung cancer in patients with rs3743073G mutant genotypes of CHRNA3 gene is increased markedly, especially in those more than 60 years old, males and smoking ones.

  4. Neuronal nicotinic acetylcholine receptors serve as sensitive targets that mediate β-amyloid neurotoxicity

    Institute of Scientific and Technical Information of China (English)

    Qiang LIU; Jie WU

    2006-01-01

    Alzheimer's disease (AD) is the most common form of brain dementia characterized by the accumulation of β-amyloid peptides (Aβ) and loss of forebrain cholinergic neurons. Aβ accumulation and aggregation are thought to contribute to cholinergic neuronal degeneration, in turn causing learning and memory deficits, but the specific targets that mediate Aβ neurotoxicity remain elusive. Recently, accumlating lines of evidence have demonstrated that Aβ directly modulates the function of neuronal nicotinic acetylcholine receptors (nAChRs), which leads to the new hypothesis that neuronal nAChRs may serve as important targets that mediate Aβ neurotoxicity. In this review, we summarize current studies performed in our laboratory and in others to address the question of how Aβ modulates neuronal nAChRs, especially nAChR subunit function.

  5. Halogenated and isosteric cytisine derivatives with increased affinity and functional activity at nicotinic acetylcholine receptors.

    Science.gov (United States)

    Fitch, Richard W; Kaneko, Yumika; Klaperski, Paul; Daly, John W; Seitz, Gunther; Gündisch, Daniela

    2005-02-15

    A series of pyridone ring-modified derivatives of (7R,9S)-(-)-cytisine were evaluated for affinity and functional activity at neuromuscular alpha1beta1gammadelta, ganglionic alpha3beta4, and central neuronal alpha4beta2 subtypes of nicotinic receptors. Halogenation at the 3-position improved affinity and functional activity, while substitution at the 5-position led to modest decreases in both, and disubstitution led to near abolition of functional activities and could be correlated with the electron-withdrawing ability of the halogen. Subtype selectivities of the halogenated derivatives were altered relative to cytisine in a substitution-dependent manner. Caulophylline methiodide was less potent than cytisine, but retained significant activity. Thiocytisine was relatively weak in potency and efficacy, but was significantly selective for the alpha4beta2 subtype.

  6. Water-mediated conformational transitions in nicotinic receptor M2 helix bundles: a molecular dynamics study.

    Science.gov (United States)

    Sankararamakrishnan, R; Sansom, M S

    1995-12-27

    The ion channel of the nicotinic acetylcholine receptor is a water-filled pore formed by five M2 helix segments, one from each subunit. Molecular dynamics simulations on bundles of five M2 alpha 7 helices surrounding a central column of water and with caps of water molecules at either end of the pore have been used to explore the effects of intrapore water on helix packing. Interactions of water molecules with the N-terminal polar sidechains lead to a conformational transition from right- to left-handed supercoils during these stimulations. These studies reveal that the pore formed by the bundle of M2 helices is flexible. A structural role is proposed for water molecules in determining the geometry of bundles of isolated pore-forming helices.

  7. 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...

  8. Not so Cool? Menthol’s discovered actions on the nicotinic receptor and its implications for nicotine addiction

    OpenAIRE

    2013-01-01

    Nicotine cigarette smoke is a large public health burden worldwide, contributing to various types of disease. Anti-tobacco media campaigns and control programs have significantly reduced smoking in the United States, yet trends for menthol cigarette smoking have not been as promising. Menthol cigarette smoking is particularly prevalent among young adults and African Americans, with implications for long-term impacts on health care. Continuing high rates of menthol cigarette addiction call int...

  9. Cytisine derivatives as ligands for neuronal nicotine receptors and with various pharmacological activities.

    Science.gov (United States)

    Boido, Caterina Canu; Tasso, Bruno; Boido, Vito; Sparatore, Fabio

    2003-03-01

    Neuronal nicotinic acetylcholine receptors (nAChRs) form a family of ACh-gated cation channels made up of different subtypes. They are widely distributed in peripheral and central nervous systems and are involved in complex cerebral processes as learning, memory, nociception, movement, etc. The possibility that subtype-selective ligands be used in the treatment of CNS disorders promoted the synthesis of a large number of structural analogues of nicotine and epibatidine, two very potent nAChR agonists. Pursuing our long standing research on the structural modification of quinolizidine alkaloids, we devoted our attention to cytisine, another very potent ligand for many nAChR subtypes. Thus a systematic structural modification of cytisine was undertaken in order to obtain compounds of potential therapeutic interest at peripheral as well as central level, with a particular concern for achieving nAChR subtype selective ligands. Up to the present more than 80 cytisine derivatives, mainly of N-substitution and a few by modifying the pyridone ring, have been prepared. The biological results, which concern so far about an half of the prepared compounds, indicate that the introduction of a nitro group in position 3 of the pyridone nucleus further enhances the high affinity of cytisine, while the introduction of substituents on the basic nitrogen, though reducing in different degrees the affinity, gives rise to compounds with a higher selectivity for central (alpha(4)beta(2)) versus gangliar (alpha(3)-containing) receptor subtype. On the other hand, the analgesic, antihypertensive and inotropic activities found in some N-substituted cytisines, represent an attractive starting point for the development of more active compounds.

  10. Modulation of eosinophil activation in vitro by a nicotinic receptor agonist.

    Science.gov (United States)

    Blanchet, Marie-Renée; Langlois, Anick; Israël-Assayag, Evelyne; Beaulieu, Marie-Josée; Ferland, Claudine; Laviolette, Michel; Cormier, Yvon

    2007-05-01

    Nicotinic receptor agonists decreased the infiltration of eosinophils into the lung and airways in a mouse model of asthma. To better understand the mechanisms implicated in this anti-inflammatory phenomenon, the expression of nicotinic acetylcholine receptors (nAChRs) and the effect of dimethylphenylpiperazinium (DMPP), a nonselective nAChR agonist, on human blood eosinophils were studied. The expression of alpha-3, -4, and -7 nAChR subunits on human blood eosinophils was measured by cell ELISA and immunocytochemistry. mRNA expression for all three subunits was evaluated by quantitative RT-PCR. The effect of DMPP on leukotriene C4 (LTC4) and matrix metalloproteinase-9 (MMP-9) production, eosinophil migration, and intracellular calcium mobilization was measured. The results show that the alpha-3, -4, and -7 nAChR subunits and mRNAs are expressed by blood eosinophils. In vitro treatment of these cells with various concentrations of DMPP reduced platelet-activating factor (PAF)-induced LTC4 production significantly. DMPP (160 microM) decreased eotaxin, and 5-oxo-6,8,11,14-eicosatetranoic acid induced eosinophil migration through Matrigel by 40.9% and 55.5%, respectively. This effect was reversed by the nAChR antagonist mecamylamine. In addition, DMPP reduced MMP-9 release and the inositol 1,4,5-triphosphate-dependent intracellular calcium increase provoked by PAF. Taken together, these results indicate that functional nAChRs are expressed on eosinophils and that nAChR agonists down-regulate eosinophil function in vitro. These anti-inflammatory effects could be of interest in the treatment of allergic asthma.

  11. Blockade of CRF1 receptors in the central nucleus of the amygdala attenuates the dysphoria associated with nicotine withdrawal in rats.

    Science.gov (United States)

    Bruijnzeel, Adrie W; Ford, Jenna; Rogers, Jessica A; Scheick, Stacey; Ji, Yue; Bishnoi, Mahendra; Alexander, Jon C

    2012-03-01

    The majority of smokers relapse during the acute withdrawal phase when withdrawal symptoms are most severe. The goal of the present studies was to investigate the role of corticotropin-releasing factor (CRF) and noradrenergic transmission in the central nucleus of the amygdala (CeA) in the dysphoria associated with smoking cessation. It was investigated if blockade of CRF1 receptors, blockade of α1-adrenergic receptors, or stimulation of α2-adrenergic receptors in the CeA diminishes the deficit in brain reward function associated with nicotine withdrawal in rats. Nicotine dependence was induced by implanting minipumps that delivered a nicotine solution. Withdrawal was precipitated with the nicotinic acetylcholine receptor antagonist mecamylamine. A discrete-trial intracranial self-stimulation procedure was used to assess the negative affective aspects of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. In all the experiments, mecamylamine elevated the brain reward thresholds of the rats chronically treated with nicotine and did not affect the brain reward thresholds of the saline-treated control rats. Intra-CeA administration of the CRF1 receptor antagonist R278995/CRA0450 completely prevented the mecamylamine-induced elevations in brain reward thresholds in the nicotine-treated rats and did not affect the brain reward thresholds of the saline-treated control rats. R278995/CRA0450 has also been shown to block sigma-1 receptors but there is no evidence that this could affect negative mood states. Intra-CeA administration of the α1-adrenergic receptor antagonist prazosin or the α2-adrenergic receptor agonist clonidine did not affect the brain reward thresholds of the nicotine or saline-treated rats. These studies suggest that CRF1 receptor antagonists may diminish the dysphoria associated with smoking cessation by blocking CRF1 receptors in the CeA.

  12. Frequency-Dependent Modulation of Dopamine Release by Nicotine and Dopamine D1 Receptor Ligands: An In Vitro Fast Cyclic Voltammetry Study in Rat Striatum.

    Science.gov (United States)

    Goutier, W; Lowry, J P; McCreary, A C; O'Connor, J J

    2016-05-01

    Nicotine is a highly addictive drug and exerts this effect partially through the modulation of dopamine release and increasing extracellular dopamine in regions such as the brain reward systems. Nicotine acts in these regions on nicotinic acetylcholine receptors. The effect of nicotine on the frequency dependent modulation of dopamine release is well established and the purpose of this study was to investigate whether dopamine D1 receptor (D1R) ligands have an influence on this. Using fast cyclic voltammetry and rat corticostriatal slices, we show that D1R ligands are able to modulate the effect of nicotine on dopamine release. Nicotine (500 nM) induced a decrease in dopamine efflux at low frequency (single pulse or five pulses at 10 Hz) and an increase at high frequency (100 Hz) electrical field stimulation. The D1R agonist SKF-38393, whilst having no effect on dopamine release on its own or on the effect of nicotine upon multiple pulse evoked dopamine release, did significantly prevent and reverse the effect of nicotine on single pulse dopamine release. Interestingly similar results were obtained with the D1R antagonist SCH-23390. In this study we have demonstrated that the modulation of dopamine release by nicotine can be altered by D1R ligands, but only when evoked by single pulse stimulation, and are likely working via cholinergic interneuron driven dopamine release.

  13. 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.

  14. Peroxisome proliferator-activated receptor delta agonist attenuates nicotine suppression effect on human mesenchymal stem cell-derived osteogenesis and involves increased expression of heme oxygenase-1.

    Science.gov (United States)

    Kim, Dong Hyun; Liu, Jiayong; Bhat, Samerna; Benedict, Gregory; Lecka-Czernik, Beata; Peterson, Stephen J; Ebraheim, Nabil A; Heck, Bruce E

    2013-01-01

    Smoking has long been associated with osteoporosis, decreased bone mineral density, increased risk of bone fracture, and increased health costs. Nicotine, the main component of cigarette smoke, has major negative effects on bone metabolism and skeletal remodeling in vivo. Although osteoblasts and osteoblast-like cells have been used extensively to study the impact of nicotine, few studies have been performed on human mesenchymal stem cells (hMSCs). In this context, we examined the impact of nicotine on (a) hMSCs proliferation, (b) osteoblastic differentiation, (c) alkaline phosphatase (ALP) activity, and (d) expression of canonical genes during differentiation of hMSCs. MSCs isolated from human bone marrow were treated with different concentrations (0, 0.1, 1 and 10 μM) of nicotine for 7 days. Nicotine caused a dose-dependent decrease in cell proliferation, decreased heme oxygenase-1 (HO-1) expression (p nicotine caused a dose-dependent decrease in alizarin red staining for calcium and staining for ALP. Induction of HO-1 by peroxisome proliferator-activated receptor delta agonist (GW0742) prevented the effect of nicotine. Nicotine caused a dose-dependent reduction in the expression of BMP-2, a well-known marker for bone formation; however, this was prevented by GW0742 treatment. Therefore, induction of HO-1 prevents the deleterious effects of nicotine on osteogenesis in hMSC. This offers insight into both how nicotine affects bone remodeling and a therapeutic approach to prevent fracture and osteoporosis in smokers.

  15. Chalcones as positive allosteric modulators of α7 nicotinic acetylcholine receptors: a new target for a privileged structure.

    Science.gov (United States)

    Balsera, Beatriz; Mulet, José; Fernández-Carvajal, Asia; de la Torre-Martínez, Roberto; Ferrer-Montiel, Antonio; Hernández-Jiménez, José G; Estévez-Herrera, Judith; Borges, Ricardo; Freitas, Andiara E; López, Manuela G; García-López, M Teresa; González-Muñiz, Rosario; Pérez de Vega, María Jesús; Valor, Luis M; Svobodová, Lucie; Sala, Salvador; Sala, Francisco; Criado, Manuel

    2014-10-30

    The α7 acetylcholine nicotine receptor is a ligand-gated ion channel that is involved in cognition disorders, schizophrenia, pain and inflammation among other diseases. Therefore, the development of new agents that target this receptor has great significance. Positive allosteric modulators might be advantageous, since they facilitate receptor responses without directly interacting with the agonist binding site. Here we report the search for and further design of new positive allosteric modulators having the relatively simple chalcone structure. From the natural product isoliquiritigenin as starting point, chalcones substituted with hydroxyl groups at defined locations were identified as optimal and specific promoters of α7 nicotinic function. The most potent compound (2,4,2',5'-tetrahydroxychalcone, 111) was further characterized showing its potential as neuroprotective, analgesic and cognitive enhancer, opening the way for future developments around the chalcone structure.

  16. Effects of Isoflurane on the Actions of Neuromuscular Blockers on the Muscle Nicotine Acetylcholine Receptors

    Institute of Scientific and Technical Information of China (English)

    李传翔; 姚尚龙; 聂辉; 吕斌

    2004-01-01

    In this study, we tested the hypothesis that volatile anesthetic enhancement of muscle relaxation is the result of combined drug effects on the nicotinic acetylcholine receptors. The poly A m RNA from muscle by isolation were microinjected into Xenopus oocytes for receptor expression.Concentration-effect curves for the inhibition of Ach-induced currents were established for vecuronium, rocuranium, and isoflurane. Subsequently, inhibitory effects of NDMRs were studied in the presence of the isoflurane at a concentration equivalent to half the concentration producing a 50 %inhibition alone. All tested drugs produced rapid and readily reversible concentration-dependent inhibition. The 50 % inhibitory concentration values were 889 μmol/L (95 % CI: 711-1214μmol),33.4 μmol (95 % CI: 27.1-41.7 nmol) and 9.2 nmol (95 % CI: 7.9-12.3 nmol) for isoflurane,rocuranium and vecuronium, respectively. Coapplication of isoflurane significantly enhanced the inhibitory effects of rocuranium and vecuronium, and it was especially so at low concentration of NMDRs. Isoflurane increases the potency of NDMRs, possibly by enhancing antagonist affinity at the receptor site.

  17. BDNF up-regulates alpha7 nicotinic acetylcholine receptor levels on subpopulations of hippocampal interneurons.

    Science.gov (United States)

    Massey, Kerri A; Zago, Wagner M; Berg, Darwin K

    2006-12-01

    In the hippocampus, brain-derived neurotrophic factor (BDNF) regulates a number of synaptic components. Among these are nicotinic acetylcholine receptors containing alpha7 subunits (alpha7-nAChRs), which are interesting because of their relative abundance in the hippocampus and their high relative calcium permeability. We show here that BDNF elevates surface and intracellular pools of alpha7-nAChRs on cultured hippocampal neurons and that glutamatergic activity is both necessary and sufficient for the effect. Blocking transmission through NMDA receptors with APV blocked the BDNF effect; increasing spontaneous excitatory activity with the GABA(A) receptor antagonist bicuculline replicated the BDNF effect. BDNF antibodies blocked the BDNF-mediated increase but not the bicuculline one, consistent with enhanced glutamatergic activity acting downstream from BDNF. Increased alpha7-nAChR clusters were most prominent on interneuron subtypes known to directly innervate excitatory neurons. The results suggest that BDNF, acting through glutamatergic transmission, can modulate hippocampal output in part by controlling alpha7-nAChR levels.

  18. 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.

  19. Nicotine evoked improvement in learning and memory is mediated through NPY Y1 receptors in rat model of Alzheimer's disease.

    Science.gov (United States)

    Rangani, Ritesh J; Upadhya, Manoj A; Nakhate, Kartik T; Kokare, Dadasaheb M; Subhedar, Nishikant K

    2012-02-01

    We investigated the role of endogenous neuropeptide Y (NPY) system in nicotine-mediated improvement of learning and memory in rat model of Alzheimer's disease (AD). Intracerebroventricular (icv) colchicine treatment induced AD-like condition in rats and showed increased escape latency (decreased learning), and amnesic condition in probe test in Morris water maze. In these rats, nicotine (0.5mg/kg, intraperitoneal), NPY (100 ng/rat, icv) or NPY Y1 receptor agonist [Leu(31), Pro(34)]-NPY (0.04 ng/rat, icv) decreased escape latency by 54.76%, 55.81% and 44.18%, respectively, on day 4 of the acquisition. On the other hand, selective NPY Y1 receptor antagonist, BIBP3226 (icv) produced opposite effect (44.18%). In the probe test conducted at 24h time point, nicotine, NPY or [Leu(31), Pro(34)]-NPY increased the time spent by 72.72%, 44.11% and 26.47%, respectively; while BIBP3226 caused reduction (8.82%). It seems that while NPY or [Leu(31), Pro(34)]-NPY potentiated, BIBP3226 attenuated the learning and memory enhancing effects of nicotine. Brains of colchicine treated rats showed significant reduction in NPY-immunoreactivity in the nucleus accumbens shell (cells 62.23% and fibers 50%), bed nucleus of stria terminalis (fibers 71.58%), central nucleus of amygdala (cells 74.33%), arcuate nucleus (cells 70.97% and fibers 69.65%) and dentate gyrus (cells 58.54%). However, in these rats nicotine treatment for 4 days restored NPY-immunoreactivity to the control level. We suggest that NPY, perhaps acting via NPY Y1 receptors, might interact with the endogenous cholinergic system and play a role in improving the learning and memory processes in the rats with AD-like condition.

  20. Optical studies of nicotinic acetylcholine receptor subtypes in the guinea-pig enteric nervous system.

    Science.gov (United States)

    Obaid, A L; Nelson, M E; Lindstrom, J; Salzberg, B M

    2005-08-01

    Nicotinic transmission in the enteric nervous system (ENS) is extensive, but the role of individual nicotinic acetylcholine receptor (nAChR) subtypes in the functional connectivity of its plexuses has been elusive. Using monoclonal antibodies (mAbs) against neuronal alpha3-, alpha4-, alpha3/alpha5-, beta2-, beta4- and alpha7-subunits, combined with radioimmunoassays and immunocytochemistry, we demonstrate that guinea-pig enteric ganglia contain all of these nAChR-subunits with the exception of alpha4, and so, differ from mammalian brain. This information alone, however, is insufficient to establish the functional role of the identified nAChR-subtypes within the enteric networks and, ultimately, their specific contributions to gastrointestinal physiology. We have used voltage-sensitive dyes and a high-speed CCD camera, in conjunction with specific antagonists to various nAChRs, to elucidate some of the distinct contributions of the individual subtypes to the behaviour of enteric networks. In the guinea-pig, the submucous plexus has the extraordinary advantage that it is virtually two-dimensional, permitting optical recording, with single cell resolution, of the electrical activity of all of its neurones. In this plexus, the block of alpha3beta2-, alpha3beta4- and/or alpha7-nAChRs always results in a decrease in the magnitude of the synaptic response. However, the magnitude of the fast excitatory post-synaptic potentials (epsps) evoked by electrical stimulation of a neighbouring ganglion varies from cell to cell, reflecting the differential expression of subunits already observed using mAbs, as well as the strengths of the activated synaptic inputs. At the same time, we observe that submucous neurones have a substantial mecamylamine (Mec)-insensitive (non-nicotinic) component to their fast epsps, which may point to the presence of purinergic or serotonergic fast epsps in this system. In the myenteric plexus, on the other hand, the antagonist-induced changes in the

  1. Expression of neuronal nicotinic acetylcholine receptor subunit mRNAs in rat hippocampal GABAergic interneurons.

    Science.gov (United States)

    Son, Jong-Hyun; Winzer-Serhan, Ursula H

    2008-11-10

    Hippocampal inhibitory interneurons are a diverse population of cells widely scattered in the hippocampus, where they regulate hippocampal circuit activity. The hippocampus receives cholinergic projections from the basal forebrain, and functional studies have suggested the presence of different subtypes of nicotinic acetylcholine receptors (AChRs) on gamma-aminobutyric acid (GABA)ergic interneurons. Single-cell polymerase chain reaction analysis had confirmed that several nAChR subunit mRNAs are co-expressed with glutamate decarboxylase 67 (GAD67), the marker for GABAergic interneurons. In this anatomical study, we systematically investigated the co-expression of GAD67 with different nAChR subunits by using double in situ hybridization with a digoxigenin-labeled GAD67 probe and (35)S-labeled probes for nAChR subunits (alpha2, alpha3, alpha4, alpha5, alpha6, alpha7, beta2, beta3, and beta4). The results revealed that most GAD67-positive interneurons expressed beta2, and 67 % also expressed alpha7 mRNA. In contrast, mRNA expression of other subunits was limited; only 13 % of GAD67-positive neurons co-expressed alpha4, and less than 10% expressed transcripts for alpha2, alpha3, alpha5, or beta4. Most GAD67/alpha2 co-expression was located in CA1/CA3 stratum oriens, and GAD67/alpha5 co-expression was predominantly detected in CA1/CA3 stratum radiatum/lacunosum moleculare and the dentate gyrus. Expression of alpha6 and beta3 mRNAs was rarely detected in the hippocampus, and mRNAs were not co-expressed with GAD67. These findings suggest that the majority of nicotinic responses in GABAergic interneurons should be mediated by a homomeric alpha7 or heteromeric alpha7*-containing nAChRs. Other possible combinations such as alpha2beta2*, alpha4beta2*, or alpha5beta2* heteromeric nAChRs could contribute to functional nicotinic response in subsets of GABAergic interneurons but overall would have a minor role.

  2. Alpha7 nicotinic acetylcholine receptor agonists and PAMs as adjunctive treatment in schizophrenia. An experimental study.

    Science.gov (United States)

    Marcus, Monica M; Björkholm, Carl; Malmerfelt, Anna; Möller, Annie; Påhlsson, Ninni; Konradsson-Geuken, Åsa; Feltmann, Kristin; Jardemark, Kent; Schilström, Björn; Svensson, Torgny H

    2016-09-01

    Nicotine has been found to improve cognition and reduce negative symptoms in schizophrenia and a genetic and pathophysiological link between the α7 nicotinic acetylcholine receptors (nAChRs) and schizophrenia has been demonstrated. Therefore, there has been a large interest in developing drugs affecting the α7 nAChRs for schizophrenia. In the present study we investigated, in rats, the effects of a selective α7 agonist (PNU282987) and a α7 positive allosteric modulator (PAM; NS1738) alone and in combination with the atypical antipsychotic drug risperidone for their utility as adjunct treatment in schizophrenia. Moreover we also investigated their utility as adjunct treatment in depression in combination with the SSRI citalopram. We found that NS1738 and to some extent also PNU282987, potentiated a subeffective dose of risperidone in the conditioned avoidance response test. Both drugs also potentiated the effect of a sub-effective concentration of risperidone on NMDA-induced currents in pyramidal cells of the medial prefrontal cortex. Moreover, NS1738 and PNU282987 enhanced recognition memory in the novel object recognition test, when given separately. Both drugs also potentiated accumbal but not prefrontal risperidone-induced dopamine release. Finally, PNU282987 reduced immobility in the forced swim test, indicating an antidepressant-like effect. Taken together, our data support the utility of drugs targeting the α7 nAChRs, perhaps especially α7 PAMs, to potentiate the effect of atypical antipsychotic drugs. Moreover, our data suggest that α7 agonists and PAMs can be used to ameliorate cognitive symptoms in schizophrenia and depression.

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

    Science.gov (United States)

    Jensen, Majbrit M; Arvaniti, Maria; Mikkelsen, Jens D; Michalski, Dominik; Pinborg, Lars H; Härtig, Wolfgang; Thomsen, Morten S

    2015-04-01

    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 and modulating their function. Hence, changes in nAChR regulatory proteins such as Lynx proteins could underlie the dysregulation of nAChRs in AD. Using Western blotting, we detected bands corresponding to the Lynx proteins prostate stem cell antigen (PSCA) and Lypd6 in human cortex indicating that both proteins are present in the human brain. We further showed that PSCA forms stable complexes with the α4 nAChR subunit and decreases nicotine-induced extracellular-signal regulated kinase phosphorylation in PC12 cells. In addition, we analyzed protein levels of PSCA and Lypd6 in postmortem tissue of medial frontal gyrus from AD patients and found significantly increased PSCA levels (approximately 70%). In contrast, no changes in Lypd6 levels were detected. In concordance with our findings in AD patients, PSCA levels were increased in the frontal cortex of triple transgenic mice with an AD-like pathology harboring human transgenes that cause both age-dependent β-amyloidosis and tauopathy, whereas Tg2576 mice, which display β-amyloidosis only, had unchanged PSCA levels compared to wild-type animals. These findings identify PSCA as a nAChR-binding protein in the human brain that is affected in AD, suggesting that PSCA-nAChR interactions may be involved in the cognitive dysfunction observed in AD. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Partial blockade of nicotinic acetylcholine receptors improves the counterregulatory response to hypoglycemia in recurrently hypoglycemic rats.

    Science.gov (United States)

    LaGamma, Edmund F; Kirtok, Necla; Chan, Owen; Nankova, Bistra B

    2014-10-01

    Recurrent exposure to hypoglycemia can impair the normal counterregulatory hormonal responses that guard against hypoglycemia, leading to hypoglycemia unawareness. This pathological condition known as hypoglycemia-associated autonomic failure (HAAF) is the main adverse consequence that prevents individuals with type 1 diabetes mellitus from attaining the long-term health benefits of tight glycemic control. The underlying molecular mechanisms responsible for the progressive loss of the epinephrine response to subsequent bouts of hypoglycemia, a hallmark sign of HAAF, are largely unknown. Normally, hypoglycemia triggers both the release and biosynthesis of epinephrine through activation of nicotinic acetylcholine receptors (nAChR) on the adrenal glands. We hypothesize that excessive cholinergic stimulation may contribute to impaired counterregulation. Here, we tested whether administration of the nAChR partial agonist cytisine to reduce postganglionic synaptic activity can preserve the counterregulatory hormone responses in an animal model of HAAF. Compared with nicotine, cytisine has limited efficacy to activate nAChRs and stimulate epinephrine release and synthesis. We evaluated adrenal catecholamine production and secretion in nondiabetic rats subjected to two daily episodes of hypoglycemia for 3 days, followed by a hyperinsulinemic hypoglycemic clamp on day 4. Recurrent hypoglycemia decreased epinephrine responses, and this was associated with suppressed TH mRNA induction (a measure of adrenal catecholamine synthetic capacity). Treatment with cytisine improved glucagon responses as well as epinephrine release and production in recurrently hypoglycemic animals. These data suggest that pharmacological manipulation of ganglionic nAChRs may be promising as a translational adjunctive therapy to avoid HAAF in type 1 diabetes mellitus.

  5. Carrier-mediated release of monoamines induced by the nicotinic acetylcholine receptor agonist DMPP.

    Science.gov (United States)

    Szász, Bernadett K; Mayer, Aliz; Zsilla, Gabriella; Lendvai, Balázs; Vizi, E Sylvester; Kiss, János P

    2005-09-01

    We have previously shown that dimethylphenylpiperazinium (DMPP) increases the release of noradrenaline (NA) from rat hippocampal slices via two distinct mechanisms: a nicotinic acetylcholine receptor (nAChR)-mediated exocytosis and a carrier-mediated release induced by the reversal of NA transporters. Our aim was to investigate whether other monoaminergic systems are also affected by the multiple actions of DMPP. In our experiments DMPP dose-dependently increased the release of dopamine (DA) and serotonin (5-HT) from rat striatal and hippocampal slices, respectively. The dual effect was observed, however, only in case of DA at a lower DMPP concentration (30 microM), where the response was partly inhibited by mecamylamine, TTX and Ca2+-free medium (nAChR-mediated exocytosis) while the other part of the response was blocked only by the DA uptake inhibitor nomifensine (carrier-mediated release). In contrast, the DMPP-evoked 5-HT release and the DA release induced by high concentration DMPP was not inhibited by nicotinic antagonists, TTX and Ca2+-free medium but only by selective uptake inhibitors. In addition, DMPP dose-dependently inhibited the [3H]DA and [3H]5-HT uptake in striatal and hippocampal synaptosome preparation with an IC50 of 3.18 and 0.49 microM, respectively. Our data show that DMPP interacts with monoamine transporters and induces a substantial carrier-mediated release of DA and 5-HT, therefore caution is needed for the interpretation of data, when this drug is used as a nAChR agonist.

  6. Discovery of peptide ligands through docking and virtual screening at nicotinic acetylcholine receptor homology models.

    Science.gov (United States)

    Leffler, Abba E; Kuryatov, Alexander; Zebroski, Henry A; Powell, Susan R; Filipenko, Petr; Hussein, Adel K; Gorson, Juliette; Heizmann, Anna; Lyskov, Sergey; Tsien, Richard W; Poget, Sébastien F; Nicke, Annette; Lindstrom, Jon; Rudy, Bernardo; Bonneau, Richard; Holford, Mandë

    2017-09-19

    Venom peptide toxins such as conotoxins play a critical role in the characterization of nicotinic acetylcholine receptor (nAChR) structure and function and have potential as nervous system therapeutics as well. However, the lack of solved structures of conotoxins bound to nAChRs and the large size of these peptides are barriers to their computational docking and design. We addressed these challenges in the context of the α4β2 nAChR, a widespread ligand-gated ion channel in the brain and a target for nicotine addiction therapy, and the 19-residue conotoxin α-GID that antagonizes it. We developed a docking algorithm, ToxDock, which used ensemble-docking and extensive conformational sampling to dock α-GID and its analogs to an α4β2 nAChR homology model. Experimental testing demonstrated that a virtual screen with ToxDock correctly identified three bioactive α-GID mutants (α-GID[A10V], α-GID[V13I], and α-GID[V13Y]) and one inactive variant (α-GID[A10Q]). Two mutants, α-GID[A10V] and α-GID[V13Y], had substantially reduced potency at the human α7 nAChR relative to α-GID, a desirable feature for α-GID analogs. The general usefulness of the docking algorithm was highlighted by redocking of peptide toxins to two ion channels and a binding protein in which the peptide toxins successfully reverted back to near-native crystallographic poses after being perturbed. Our results demonstrate that ToxDock can overcome two fundamental challenges of docking large toxin peptides to ion channel homology models, as exemplified by the α-GID:α4β2 nAChR complex, and is extendable to other toxin peptides and ion channels. ToxDock is freely available at rosie.rosettacommons.org/tox_dock.

  7. 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.

  8. Understanding the Bases of Function and Modulation of α7 Nicotinic Receptors: Implications for Drug Discovery.

    Science.gov (United States)

    Corradi, Jeremías; Bouzat, Cecilia

    2016-09-01

    The nicotinic acetylcholine receptor (nAChR) belongs to a superfamily of pentameric ligand-gated ion channels involved in many physiologic and pathologic processes. Among nAChRs, receptors comprising the α7 subunit are unique because of their high Ca(2+) permeability and fast desensitization. nAChR agonists elicit a transient ion flux response that is further sustained by the release of calcium from intracellular sources. Owing to the dual ionotropic/metabotropic nature of α7 receptors, signaling pathways are activated. The α7 subunit is highly expressed in the nervous system, mostly in regions implicated in cognition and memory and has therefore attracted attention as a novel drug target. Additionally, its dysfunction is associated with several neuropsychiatric and neurologic disorders, such as schizophrenia and Alzheimer's disease. α7 is also expressed in non-neuronal cells, particularly immune cells, where it plays a role in immunity, inflammation, and neuroprotection. Thus, α7 potentiation has emerged as a therapeutic strategy for several neurologic and inflammatory disorders. With unique activation properties, the receptor is a sensitive drug target carrying different potential binding sites for chemical modulators, particularly agonists and positive allosteric modulators. Although macroscopic and single-channel recordings have provided significant information about the underlying molecular mechanisms and binding sites of modulatory compounds, we know just the tip of the iceberg. Further concerted efforts are necessary to effectively exploit α7 as a drug target for each pathologic situation. In this article, we focus mainly on the molecular basis of activation and drug modulation of α7, key pillars for rational drug design.

  9. Invariant Aspartic Acid in Muscle Nicotinic Receptor Contributes Selectively to the Kinetics of Agonist Binding

    Science.gov (United States)

    Lee, Won Yong; Sine, Steven M.

    2004-01-01

    We examined functional contributions of interdomain contacts within the nicotinic receptor ligand binding site using single channel kinetic analyses, site-directed mutagenesis, and a homology model of the major extracellular region. At the principal face of the binding site, the invariant αD89 forms a highly conserved interdomain contact near αT148, αW149, and αT150. Patch-clamp recordings show that the mutation αD89N markedly slows acetylcholine (ACh) binding to receptors in the resting closed state, but does not affect rates of channel opening and closing. Neither αT148L, αT150A, nor mutations at both positions substantially affects the kinetics of receptor activation, showing that hydroxyl side chains at these positions are not hydrogen bond donors for the strong acceptor αD89. However substituting a negative charge at αT148, but not at αT150, counteracts the effect of αD89N, demonstrating that a negative charge in the region of interdomain contact confers rapid association of ACh. Interpreted within the structural framework of ACh binding protein and a homology model of the receptor ligand binding site, these results implicate main chain amide groups in the domain harboring αW149 as principal hydrogen bond donors for αD89. The specific effect of αD89N on ACh association suggests that interdomain hydrogen bonding positions αW149 for optimal interaction with ACh. PMID:15504901

  10. Nicotinic acetylcholine receptor-mediated calcium signaling in the nervous system

    Institute of Scientific and Technical Information of China (English)

    Jian-xin SHEN; Jerrel L YAKEL

    2009-01-01

    Based on the composition of the five subunits forming functional neuronal nicotinic acetylcholine receptors (nAChRs), they are grouped into either heteromeric (comprising both α and β subunits) or homomeric (comprising only α subunits) recep-tors. The nAChRs are known to be differentially permeable to calcium ions, with the α7 nAChR subtype having one of the highest permeabilities to calcium. Calcium influx through nAChRs, particularly through the α-bungarotoxin-sensitive α7-containing nAChRs, is a very efficient way to raise cytoplasmic calcium levels. The activation of nAChRs can mediate three types of cytoplasmic calcium signals: (1) direct calcium influx through the nAChRs, (2) indirect calcium influx through voltage-dependent calcium channels (VDCCs) which are activated by the nAChR-mediated depolarization, and (3) calcium-induced calcium release (CICR) (triggered by the first two sources) from the endoplasmic reticulum (ER) through the ryanodine receptors and inositol (1,4,5)-triphosphate receptors (IP3Rs). Downstream signaling events mediated by nAChR-mediated calcium responses can be grouped into instantaneous effects (such as neurotransmitter release, which can occur in milliseconds after nAChR activation), short-term effects (such as the recovery of nAChR desensitization through cellular signaling cascades), and long-term effects (such as neuroprotection via gene expression). In addition, nAChR activity can be regulated by cytoplasmic calcium levels, suggesting a complex reciprocal relationship. Further advances in imaging techniques, animal models, and more potent and subtype-selective ligands for neuronal nAChRs would help in understand-ing the neuronal nAChR-mediated calcium signaling, and lead to the development of improved therapeutic treatments.

  11. 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.

  12. Mesoionic insecticides: a novel class of insecticides that modulate nicotinic acetylcholine receptors.

    Science.gov (United States)

    Holyoke, Caleb W; Cordova, Daniel; Zhang, Wenming; Barry, James D; Leighty, Robert M; Dietrich, Robert F; Rauh, James J; Pahutski, Thomas F; Lahm, George P; Tong, My-Hanh Thi; Benner, Eric A; Andreassi, John L; Smith, Rejane M; Vincent, Daniel R; Christianson, Laurie A; Teixeira, Luis A; Singh, Vineet; Hughes, Kenneth A

    2017-04-01

    As the world population grows towards 9 billion by 2050, it is projected that food production will need to increase by 60%. A critical part of this growth includes the safe and effective use of insecticides to reduce the estimated 20-49% loss of global crop yields owing to pests. The development of new insecticides will help to sustain this protection and overcome insecticide resistance. A novel class of mesoionic compounds has been discovered, with exceptional insecticidal activity on a range of Hemiptera and Lepidoptera. These compounds bind to the orthosteric site of the nicotinic acetylcholine receptor and result in a highly potent inhibitory action at the receptor with minimal agonism. The synthesis, biological activity, optimization and mode of action will be discussed. Triflumezopyrim insect control will provide a powerful tool for control of hopper species in rice throughout Asia. Dicloromezotiaz can provide a useful control tool for lepidopteran pests, with an underexploited mode of action among these pests. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  13. 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.

  14. alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

    Science.gov (United States)

    de Fiebre, Nancyellen C; de Fiebre, Christopher M

    2005-01-03

    The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

  15. Monkey adrenal chromaffin cells express α6β4* nicotinic acetylcholine receptors.

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    Alicia Hernández-Vivanco

    Full Text Available Nicotinic acetylcholine receptors (nAChRs that contain α6 and β4 subunits have been demonstrated functionally in human adrenal chromaffin cells, rat dorsal root ganglion neurons, and on noradrenergic terminals in the hippocampus of adolescent mice. In human adrenal chromaffin cells, α6β4* nAChRs (the asterisk denotes the possible presence of additional subunits are the predominant subtype whereas in rodents, the predominant nAChR is the α3β4* subtype. Here we present molecular and pharmacological evidence that chromaffin cells from monkey (Macaca mulatta also express α6β4* receptors. PCR was used to show the presence of transcripts for α6 and β4 subunits and pharmacological characterization was performed using patch-clamp electrophysiology in combination with α-conotoxins that target the α6β4* subtype. Acetylcholine-evoked currents were sensitive to inhibition by BuIA[T5A,P6O] and MII[H9A,L15A]; α-conotoxins that inhibit α6-containing nAChRs. Two additional agonists were used to probe for the expression of α7 and β2-containing nAChRs. Cells with currents evoked by acetylcholine were relatively unresponsive to the α7-selctive agonist choline but responded to the agonist 5-I-A-85380. These studies provide further insights into the properties of natively expressed α6β4* nAChRs.

  16. Nicotine inhibits memory CTL programming.

    Directory of Open Access Journals (Sweden)

    Zhifeng Sun

    Full Text Available Nicotine is the main tobacco component responsible for tobacco addiction and is used extensively in smoking and smoking cessation therapies. However, little is known about its effects on the immune system. We confirmed that multiple nicotinic receptors are expressed on mouse and human cytotoxic T lymphocytes (CTLs and demonstrated that nicotinic receptors on mouse CTLs are regulated during activation. Acute nicotine presence during activation increases primary CTL expansion in vitro, but impairs in vivo expansion after transfer and subsequent memory CTL differentiation, which reduces protection against subsequent pathogen challenges. Furthermore, nicotine abolishes the regulatory effect of rapamycin on memory CTL programming, which can be attributed to the fact that rapamycin enhances expression of nicotinic receptors. Interestingly, naïve CTLs from chronic nicotine-treated mice have normal memory programming, which is impaired by nicotine during activation in vitro. In conclusion, simultaneous exposure to nicotine and antigen during CTL activation negatively affects memory development.

  17. Nicotine inhibits memory CTL programming.

    Science.gov (United States)

    Sun, Zhifeng; Smyth, Kendra; Garcia, Karla; Mattson, Elliot; Li, Lei; Xiao, Zhengguo

    2013-01-01

    Nicotine is the main tobacco component responsible for tobacco addiction and is used extensively in smoking and smoking cessation therapies. However, little is known about its effects on the immune system. We confirmed that multiple nicotinic receptors are expressed on mouse and human cytotoxic T lymphocytes (CTLs) and demonstrated that nicotinic receptors on mouse CTLs are regulated during activation. Acute nicotine presence during activation increases primary CTL expansion in vitro, but impairs in vivo expansion after transfer and subsequent memory CTL differentiation, which reduces protection against subsequent pathogen challenges. Furthermore, nicotine abolishes the regulatory effect of rapamycin on memory CTL programming, which can be attributed to the fact that rapamycin enhances expression of nicotinic receptors. Interestingly, naïve CTLs from chronic nicotine-treated mice have normal memory programming, which is impaired by nicotine during activation in vitro. In conclusion, simultaneous exposure to nicotine and antigen during CTL activation negatively affects memory development.

  18. INHIBITION OF HUMAN A7 NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS BY THE VOLATILE ORGANIC SOLVENT TRICHLOROETHYLENE.

    Science.gov (United States)

    Volatile organic compounds such as toleune, trichloroethylene and perchloroethylene are potent and reversible blockers of voltage-gated calcium current in nerve growth factor (NGF)-differentiated pheochromocytoma (PC12) cells. It is hypothesized that effects of VOCs on ICa contri...

  19. Angiotensin AT1 and AT2 receptor antagonists modulate nicotine-evoked [³H]dopamine and [³H]norepinephrine release.

    Science.gov (United States)

    Narayanaswami, Vidya; Somkuwar, Sucharita S; Horton, David B; Cassis, Lisa A; Dwoskin, Linda P

    2013-09-01

    Tobacco smoking is the leading preventable cause of death in the United States. A major negative health consequence of chronic smoking is hypertension. Untoward addictive and cardiovascular sequelae associated with chronic smoking are mediated by nicotine-induced activation of nicotinic receptors (nAChRs) within striatal dopaminergic and hypothalamic noradrenergic systems. Hypertension involves both brain and peripheral angiotensin systems. Activation of angiotensin type-1 receptors (AT1) release dopamine and norepinephrine. The current study determined the role of AT1 and angiotensin type-2 (AT2) receptors in mediating nicotine-evoked dopamine and norepinephrine release from striatal and hypothalamic slices, respectively. The potential involvement of nAChRs in mediating effects of AT1 antagonist losartan and AT2 antagonist, 1-[[4-(dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid (PD123319) was evaluated by determining their affinities for α4β2* and α7* nAChRs using [³H]nicotine and [³H]methyllycaconitine binding assays, respectively. Results show that losartan concentration-dependently inhibited nicotine-evoked [³H]dopamine and [³H]norepinephrine release (IC₅₀: 3.9 ± 1.2 and 2.2 ± 0.7 μM; Imax: 82 ± 3 and 89 ± 6%, respectively). In contrast, PD123319 did not alter nicotine-evoked norepinephrine release, and potentiated nicotine-evoked dopamine release. These results indicate that AT1 receptors modulate nicotine-evoked striatal dopamine and hypothalamic norepinephrine release. Furthermore, AT1 receptor activation appears to be counteracted by AT2 receptor activation in striatum. Losartan and PD123319 did not inhibit [³H]nicotine or [³H]methyllycaconitine binding, indicating that these AT1 and AT2 antagonists do not interact with the agonist recognition sites on α4β2* and α7* nAChRs to mediate these effects of nicotine. Thus, angiotensin receptors contribute to the effects of

  20. Structural Characterization of the Putative Cholinergic Binding Region alpha(179-201) of the Nicotinic Acetylcholine Receptor. Part 1. Review and Experimental Design.

    Science.gov (United States)

    1993-04-01

    Dynamic Model for the Nicotinic Acetylcholine Receptor, in Computer -Assisted Modeling of Receptor-Ligand Interactions: Theoretical Aspects and...Hunkapillar, M.W., Strader, C.D., Hood, LE.-Acetylcholine receptor: complex of homologous subunits. Sceince vol. 208, pp. 1454-1457, 1980 Ragone, R

  1. Modification of the philanthotoxin-343 polyamine moiety results in different structure-activity profiles at muscle nicotinic ACh, NMDA and AMPA receptors

    DEFF Research Database (Denmark)

    Mellor, I R; Brier, T J; Pluteanu, F

    2003-01-01

    Voltage-dependent, non-competitive inhibition by philanthotoxin-343 (PhTX-343) analogues, with reduced charge or length, of nicotinic acetylcholine receptors (nAChR) of TE671 cells and ionotropic glutamate receptors (N-methyl-D-aspartate receptors (NMDAR) and alpha-amino-3-hydroxy-5-methyl-4-isox...

  2. Increased Sensitivity of the Neuronal Nicotinic Receptor α2 Subunit Causes Familial Epilepsy with Nocturnal Wandering and Ictal Fear

    OpenAIRE

    Aridon, Paolo; Marini, Carla; Di Resta, Chiara; Brilli, Elisa; De Fusco, Maurizio; Politi, Fausta; Parrini, Elena; Manfredi, Irene; Pisano, Tiziana; Pruna, Dario; Curia, Giulia; Cianchetti, Carlo; Pasqualetti, Massimo; Becchetti, Andrea; Guerrini, Renzo

    2006-01-01

    Sleep has traditionally been recognized as a precipitating factor for some forms of epilepsy, although differential diagnosis between some seizure types and parasomnias may be difficult. Autosomal dominant frontal lobe epilepsy is characterized by nocturnal seizures with hyperkinetic automatisms and poorly organized stereotyped movements and has been associated with mutations of the α4 and β2 subunits of the neuronal nicotinic acetylcholine receptor. We performed a clinical and molecular gene...

  3. Differential Effects of Quercetin and Quercetin Glycosides on Human α7 Nicotinic Acetylcholine Receptor-Mediated Ion Currents

    OpenAIRE

    Lee, Byung-Hwan; Choi, Sun-Hye; Kim, Hyeon-Joong; Jung, Seok-Won; Hwang, Sung-Hee; Pyo, Mi-Kyung; Rhim, Hyewhon; Kim, Hyoung-Chun; Kim, Ho-Kyoung; Lee, Sang-Mok; Nah, Seung-Yeol

    2016-01-01

    Quercetin is a flavonoid usually found in fruits and vegetables. Aside from its antioxidative effects, quercetin, like other flavonoids, has a various neuropharmacological actions. Quercetin-3-O-rhamnoside (Rham1), quercetin-3-O-rutinoside (Rutin), and quercetin-3-(2(G)-rhamnosylrutinoside (Rham2) are mono-, di-, and tri-glycosylated forms of quercetin, respectively. In a previous study, we showed that quercetin can enhance α7 nicotinic acetylcholine receptor (α7 nAChR)-mediated ion currents....

  4. Thyroid Receptor β Involvement in the Effects of Acute Nicotine on Hippocampus-Dependent Memory

    OpenAIRE

    Leach, Prescott T.; Kenney, Justin W.; Connor, David; Gould, Thomas J.

    2015-01-01

    Cigarette smoking is common despite adverse health effects. Nicotine’s effects on learning may contribute to addiction by enhancing drug-context associations. Effects of nicotine on learning could be direct or could occur by altering systems that modulate cognition. Because thyroid signaling can alter cognition and nicotine/smoking may change thyroid function, nicotine could affect learning through changes in thyroid signaling. These studies investigate the functional contributions of thyroid...

  5. 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

  6. Activation of nicotinic cholinergic receptors prevents ventilator-induced lung injury in rats.

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    Fabienne Brégeon

    Full Text Available Respiratory distress syndrome is responsible for 40 to 60 percent mortality. An over mortality of about 10 percent could result from additional lung injury and inflammation due to the life-support mechanical ventilation, which stretches the lung. It has been recently demonstrated, in vitro, that pharmacological activation of the alpha 7 nicotinic receptors (α7-nAChR could down regulate intracellular mediators involved in lung cell inflammatory response to stretch. Our aim was to test in vivo the protective effect of the pharmacological activation of the α7-nAChR against ventilator-induced lung injury (VILI. Anesthetized rats were ventilated for two hours with a high stretch ventilation mode delivering a stroke volume large enough to generate 25-cmH(2O airway pressure, and randomly assigned to four groups: pretreated with parenteral injection of saline or specific agonist of the α7-nAChR (PNU-282987, or submitted to bilateral vagus nerve electrostimulation while pre-treated or not with the α7-nAChR antagonist methyllycaconitine (MLA. Controls ventilated with a conventional stroke volume of 10 mL/kg gave reference data. Physiological indices (compliance of the respiratory system, lung weight, blood oxygenation, arterial blood pressure and lung contents of inflammatory mediators (IL-6 measured by ELISA, substance P assessed using HPLC were severely impaired after two hours of high stretch ventilation (sham group. Vagal stimulation was able to maintain the respiratory parameters close to those obtained in Controls and reduced lung inflammation except when associated to nicotinic receptor blockade (MLA, suggesting the involvement of α7-nAChR in vagally-mediated protection against VILI. Pharmacological pre-treatment with PNU-282987 strongly decreased lung injury and lung IL-6 and substance P contents, and nearly abolished the increase in plasmatic IL-6 levels. Pathological examination of the lungs confirmed the physiological differences observed

  7. Effects of donepezil treatment on rat nicotinic acetylcholine receptor levels in vivo and in vitro.

    Science.gov (United States)

    Reid, Richard T; Sabbagh, Marwan N

    2003-12-01

    Research on acetylcholinesterase inhibitors (ChEIs) indicates that long term exposure increases the level of nicotinic acetylcholine receptors (nAChRs) but the effects of donepezil on nAChRs are not well studied. Therefore, we investigated the effects of sub-chronic donepezil administration on nAChRs in rats and rat pheochromocytoma PC-12 cells. Male Sprague Dawley rats were administered donepezil (0.7 and 2.4 micromoles/kg), nicotine (2.5 micromoles/kg) or saline subcutaneously twice daily for 14 days, PC-12 cells were incubated with 10(-6) to 10(-4) M donepezil for 72 hours and nAChR levels were determined by receptor binding assay using the nAChR ligands [3H]-epibatidine (EPI) for non-alpha 7 nAChRs and [3H]-methyllyconitine (MLA) for alpha 7 nAChRs. Chronic donepezil administration at 1.4 micromoles/kg/day and 4.8 micromoles/ kg/day significantly increased [3H]-epibatidine binding in the cortex to 126 +/- 1.3% and 127 +/- 3.2% of the saline control animals, respectively. [3H]-MLA binding in the cortex increased to 114 +/- 4.4% and 124 +/- 2.8% of the control group for the high and low dose groups, respectively. Hippocampal [3H]-EPI binding in the low dose and high dose groups significantly increased to 135 +/- 3.6% and 125 +/- 4.6% of the controls, respectively while there were no changes in the level of [3H]-MLA binding. In striatal homogenates, neither [3H]-EPI nor [3H]-MLA binding were significantly effected at either dose of donepezil. In PC-12 cells, [3H]-EPI binding was increased at the non-physiological 10(-4)M concentration only. There was no effect of donepezil on [3H]-MLA binding at any concentration examined. These results indicate that donepezil increases cortical alpha 7 and non-alpha 7 nAChRs, hippocampal non-alpha 7 nAChRs but does not influence striatal nAChR levels. Furthermore, the lack of an effect on the alpha 7-nAChRs in PC-12 cells suggests that the increase in cortical alpha 7 nAChRs may be an indirect effect of increased acetylcholine

  8. Inhibition of α9α10 nicotinic acetylcholine receptors prevents chemotherapy-induced neuropathic pain

    Science.gov (United States)

    Romero, Haylie K.; Christensen, Sean B.; Gajewiak, Joanna; Ramachandra, Renuka; Elmslie, Keith S.; Vetter, Douglas E.; Ghelardini, Carla; Iadonato, Shawn P.; Mercado, Jose L.; Olivera, Baldomera M.; McIntosh, J. Michael

    2017-01-01

    Opioids are first-line drugs for moderate to severe acute pain and cancer pain. However, these medications are associated with severe side effects, and whether they are efficacious in treatment of chronic nonmalignant pain remains controversial. Medications that act through alternative molecular mechanisms are critically needed. Antagonists of α9α10 nicotinic acetylcholine receptors (nAChRs) have been proposed as an important nonopioid mechanism based on studies demonstrating prevention of neuropathology after trauma-induced nerve injury. However, the key α9α10 ligands characterized to date are at least two orders of magnitude less potent on human vs. rodent nAChRs, limiting their translational application. Furthermore, an alternative proposal that these ligands achieve their beneficial effects by acting as agonists of GABAB receptors has caused confusion over whether blockade of α9α10 nAChRs is the fundamental underlying mechanism. To address these issues definitively, we developed RgIA4, a peptide that exhibits high potency for both human and rodent α9α10 nAChRs, and was at least 1,000-fold more selective for α9α10 nAChRs vs. all other molecular targets tested, including opioid and GABAB receptors. A daily s.c. dose of RgIA4 prevented chemotherapy-induced neuropathic pain in rats. In wild-type mice, oxaliplatin treatment produced cold allodynia that could be prevented by RgIA4. Additionally, in α9 KO mice, chemotherapy-induced development of cold allodynia was attenuated and the milder, temporary cold allodynia was not relieved by RgIA4. These findings establish blockade of α9-containing nAChRs as the basis for the efficacy of RgIA4, and that α9-containing nAChRs are a critical target for prevention of chronic cancer chemotherapy-induced neuropathic pain. PMID:28223528

  9. The nicotinic acetylcholine receptor gene family of the honey bee, Apis mellifera.

    Science.gov (United States)

    Jones, Andrew K; Raymond-Delpech, Valerie; Thany, Steeve H; Gauthier, Monique; Sattelle, David B

    2006-11-01

    Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission and play roles in many cognitive processes. They are under intense research as potential targets of drugs used to treat neurodegenerative diseases and neurological disorders such as Alzheimer's disease and schizophrenia. Invertebrate nAChRs are targets of anthelmintics as well as a major group of insecticides, the neonicotinoids. The honey bee, Apis mellifera, is one of the most beneficial insects worldwide, playing an important role in crop pollination, and is also a valuable model system for studies on social interaction, sensory processing, learning, and memory. We have used the A. mellifera genome information to characterize the complete honey bee nAChR gene family. Comparison with the fruit fly Drosophila melanogaster and the malaria mosquito Anopheles gambiae shows that the honey bee possesses the largest family of insect nAChR subunits to date (11 members). As with Drosophila and Anopheles, alternative splicing of conserved exons increases receptor diversity. Also, we show that in one honey bee nAChR subunit, six adenosine residues are targeted for RNA A-to-I editing, two of which are evolutionarily conserved in Drosophila melanogaster and Heliothis virescens orthologs, and that the extent of editing increases as the honey bee lifecycle progresses, serving to maximize receptor diversity at the adult stage. These findings on Apis mellifera enhance our understanding of nAChR functional genomics and provide a useful basis for the development of improved insecticides that spare a major beneficial insect species.

  10. Azemiopsin from Azemiops feae Viper Venom, a Novel Polypeptide Ligand of Nicotinic Acetylcholine Receptor*

    Science.gov (United States)

    Utkin, Yuri N.; Weise, Christoph; Kasheverov, Igor E.; Andreeva, Tatyana V.; Kryukova, Elena V.; Zhmak, Maxim N.; Starkov, Vladislav G.; Hoang, Ngoc Anh; Bertrand, Daniel; Ramerstorfer, Joachim; Sieghart, Werner; Thompson, Andrew J.; Lummis, Sarah C. R.; Tsetlin, Victor I.

    2012-01-01

    Azemiopsin, a novel polypeptide, was isolated from the Azemiops feae viper venom by combination of gel filtration and reverse-phase HPLC. Its amino acid sequence (DNWWPKPPHQGPRPPRPRPKP) was determined by means of Edman degradation and mass spectrometry. It consists of 21 residues and, unlike similar venom isolates, does not contain cysteine residues. According to circular dichroism measurements, this peptide adopts a β-structure. Peptide synthesis was used to verify the determined sequence and to prepare peptide in sufficient amounts to study its biological activity. Azemiopsin efficiently competed with α-bungarotoxin for binding to Torpedo nicotinic acetylcholine receptor (nAChR) (IC50 0.18 ± 0.03 μm) and with lower efficiency to human α7 nAChR (IC50 22 ± 2 μm). It dose-dependently blocked acetylcholine-induced currents in Xenopus oocytes heterologously expressing human muscle-type nAChR and was more potent against the adult form (α1β1ϵδ) than the fetal form (α1β1γδ), EC50 being 0.44 ± 0.1 μm and 1.56 ± 0.37 μm, respectively. The peptide had no effect on GABAA (α1β3γ2 or α2β3γ2) receptors at a concentration up to 100 μm or on 5-HT3 receptors at a concentration up to 10 μm. Ala scanning showed that amino acid residues at positions 3–6, 8–11, and 13–14 are essential for binding to Torpedo nAChR. In biological activity azemiopsin resembles waglerin, a disulfide-containing peptide from the Tropidechis wagleri venom, shares with it a homologous C-terminal hexapeptide, but is the first natural toxin that blocks nAChRs and does not possess disulfide bridges. PMID:22613724

  11. Azemiopsin from Azemiops feae viper venom, a novel polypeptide ligand of nicotinic acetylcholine receptor.

    Science.gov (United States)

    Utkin, Yuri N; Weise, Christoph; Kasheverov, Igor E; Andreeva, Tatyana V; Kryukova, Elena V; Zhmak, Maxim N; Starkov, Vladislav G; Hoang, Ngoc Anh; Bertrand, Daniel; Ramerstorfer, Joachim; Sieghart, Werner; Thompson, Andrew J; Lummis, Sarah C R; Tsetlin, Victor I

    2012-08-03

    Azemiopsin, a novel polypeptide, was isolated from the Azemiops feae viper venom by combination of gel filtration and reverse-phase HPLC. Its amino acid sequence (DNWWPKPPHQGPRPPRPRPKP) was determined by means of Edman degradation and mass spectrometry. It consists of 21 residues and, unlike similar venom isolates, does not contain cysteine residues. According to circular dichroism measurements, this peptide adopts a β-structure. Peptide synthesis was used to verify the determined sequence and to prepare peptide in sufficient amounts to study its biological activity. Azemiopsin efficiently competed with α-bungarotoxin for binding to Torpedo nicotinic acetylcholine receptor (nAChR) (IC(50) 0.18 ± 0.03 μm) and with lower efficiency to human α7 nAChR (IC(50) 22 ± 2 μm). It dose-dependently blocked acetylcholine-induced currents in Xenopus oocytes heterologously expressing human muscle-type nAChR and was more potent against the adult form (α1β1εδ) than the fetal form (α1β1γδ), EC(50) being 0.44 ± 0.1 μm and 1.56 ± 0.37 μm, respectively. The peptide had no effect on GABA(A) (α1β3γ2 or α2β3γ2) receptors at a concentration up to 100 μm or on 5-HT(3) receptors at a concentration up to 10 μm. Ala scanning showed that amino acid residues at positions 3-6, 8-11, and 13-14 are essential for binding to Torpedo nAChR. In biological activity azemiopsin resembles waglerin, a disulfide-containing peptide from the Tropidechis wagleri venom, shares with it a homologous C-terminal hexapeptide, but is the first natural toxin that blocks nAChRs and does not possess disulfide bridges.

  12. Increased sensitivity of the neuronal nicotinic receptor alpha 2 subunit causes familial epilepsy with nocturnal wandering and ictal fear.

    Science.gov (United States)

    Aridon, Paolo; Marini, Carla; Di Resta, Chiara; Brilli, Elisa; De Fusco, Maurizio; Politi, Fausta; Parrini, Elena; Manfredi, Irene; Pisano, Tiziana; Pruna, Dario; Curia, Giulia; Cianchetti, Carlo; Pasqualetti, Massimo; Becchetti, Andrea; Guerrini, Renzo; Casari, Giorgio

    2006-08-01

    Sleep has traditionally been recognized as a precipitating factor for some forms of epilepsy, although differential diagnosis between some seizure types and parasomnias may be difficult. Autosomal dominant frontal lobe epilepsy is characterized by nocturnal seizures with hyperkinetic automatisms and poorly organized stereotyped movements and has been associated with mutations of the alpha 4 and beta 2 subunits of the neuronal nicotinic acetylcholine receptor. We performed a clinical and molecular genetic study of a large pedigree segregating sleep-related epilepsy in which seizures are associated with fear sensation, tongue movements, and nocturnal wandering, closely resembling nightmares and sleep walking. We identified a new genetic locus for familial sleep-related focal epilepsy on chromosome 8p12.3-8q12.3. By sequencing the positional candidate neuronal cholinergic receptor alpha 2 subunit gene (CHRNA2), we detected a heterozygous missense mutation, I279N, in the first transmembrane domain that is crucial for receptor function. Whole-cell recordings of transiently transfected HEK293 cells expressing either the mutant or the wild-type receptor showed that the new CHRNA2 mutation markedly increases the receptor sensitivity to acetylcholine, therefore indicating that the nicotinic alpha 2 subunit alteration is the underlying cause. CHRNA2 is the third neuronal cholinergic receptor gene to be associated with familial sleep-related epilepsies. Compared with the CHRNA4 and CHRNB2 mutations reported elsewhere, CHRNA2 mutations cause a more complex and finalized ictal behavior.

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

    Science.gov (United States)

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

    2007-01-01

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

  14. Nicotine Inhibits Memory CTL Programming

    OpenAIRE

    Zhifeng Sun; Kendra Smyth; Karla Garcia; Elliot Mattson; Lei Li; Zhengguo Xiao

    2013-01-01

    Nicotine is the main tobacco component responsible for tobacco addiction and is used extensively in smoking and smoking cessation therapies. However, little is known about its effects on the immune system. We confirmed that multiple nicotinic receptors are expressed on mouse and human cytotoxic T lymphocytes (CTLs) and demonstrated that nicotinic receptors on mouse CTLs are regulated during activation. Acute nicotine presence during activation increases primary CTL expansion in vitro, but imp...

  15. 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.

  16. 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.

  17. A positive relationship between harm avoidance and brain nicotinic acetylcholine receptor availability.

    Science.gov (United States)

    Storage, Steven; Mandelkern, Mark A; Phuong, Jonathan; Kozman, Maggie; Neary, Meaghan K; Brody, Arthur L

    2013-12-30

    Prior research indicates that disturbance of cholinergic neurotransmission reduces anxiety, leading to the hypothesis that people with heightened cholinergic function have a greater tendency toward anxiety-like and/or harm-avoidant behavior. We sought to determine if people with elevated levels of harm avoidance (HA), a dimension of temperament from the Temperament and Character Inventory (TCI), have high α4β2* nicotinic acetylcholine receptor (nAChR) availability. Healthy adults (n=105; 47 non-smokers and 58 smokers) underwent bolus-plus-continuous infusion positron emission tomography (PET) scanning using the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (abbreviated as 2-FA). During the uptake period of 2-FA, participants completed the TCI. The central study analysis revealed a significant association between total HA and mean nAChR availability, with higher total HA scores being linked with greater nAChR availability. In examining HA subscales, both 'Fear of Uncertainty' and 'Fatigability' were significant, based on higher levels of these characteristics being associated with greater nAChR availabilities. This study adds to a growing body of knowledge concerning the biological basis of personality and may prove useful in understanding the pathophysiology of psychiatric disorders (such as anxiety disorders) that have similar characteristics to HA. Study findings may indicate that heightened cholinergic neurotransmission is associated with increased anxiety-like traits. Published by Elsevier Ireland Ltd.

  18. Varenicline for smoking cessation: nausea severity and variation in nicotinic receptor genes.

    Science.gov (United States)

    Swan, G E; Javitz, H S; Jack, L M; Wessel, J; Michel, M; Hinds, D A; Stokowksi, R P; McClure, J B; Catz, S L; Richards, J; Zbikowski, S M; Deprey, M; McAfee, T; Conti, D V; Bergen, A W

    2012-08-01

    This study evaluated association between common and rare sequence variants in 10 nicotinic acetylcholine receptor subunit genes and the severity of nausea 21 days after initiating the standard, Food and Drug Administration-approved varenicline regimen for smoking cessation. A total of 397 participants from a randomized clinical effectiveness trial with complete clinical and DNA resequencing data were included in the analysis (mean age=49.2 years; 68.0% female). Evidence for significant association between common sequence variants in CHRNB2 and nausea severity was obtained after adjusting for age, gender and correlated tests (all P(ACT)<0.05). Individuals with the minor allele of CHRNB2 variants experienced less nausea than did those without the minor allele, consistent with previously reported findings for CHRNB2 and the occurrence of nausea and dizziness as a consequence of first smoking attempt in adolescents, and with the known neurophysiology of nausea. As nausea is the most common reason for discontinuance of varenicline, further pharmacogenetic investigations are warranted.

  19. Alpha7 Nicotinic Acetylcholine Receptor Is a Target in Pharmacology and Toxicology

    Directory of Open Access Journals (Sweden)

    Miroslav Pohanka

    2012-02-01

    Full Text Available Alpha7 nicotinic acetylcholine receptor (α7 nAChR is an important part of the cholinergic nerve system in the brain. Moreover, it is associated with a cholinergic anti-inflammatory pathway in the termination of the parasympathetic nervous system. Antagonists of α7 nAChR are a wide group represented by conotoxin and bungarotoxin. Even Alzheimer’s disease drug memantine acting as an antagonist in its side pathway belongs in this group. Agonists of α7 nAChR are suitable for treatment of multiple cognitive dysfunctions such as Alzheimer’s disease or schizophrenia. Inflammation or even sepsis can be ameliorated by the agonistic acting compounds. Preparations RG3487, SEN34625/WYE-103914, SEN12333, ABT-107, Clozapine, GTS-21, CNI-1493, and AR-R17779 are representative examples of the novel compounds with affinity toward the α7 nAChR. Pharmacological, toxicological, and medicinal significance of α7 nAChR are discussed throughout this paper.

  20. The nicotinic acetylcholine receptor gene family of the malaria mosquito, Anopheles gambiae.

    Science.gov (United States)

    Jones, Andrew K; Grauso, Marta; Sattelle, David B

    2005-02-01

    Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission in the insect nervous system and are targets of widely selling insecticides. We have identified the nAChR gene family from the genome of the malaria mosquito vector, Anopheles gambiae, to be the second complete insect nAChR gene family described following that of Drosophila melanogaster. Like Drosophila, Anopheles possesses 10 nAChR subunits with orthologous relationships evident between the two insects. Interestingly, the Anopheles orthologues of Dbeta2 and Dbeta3 possess the vicinal cysteines that define alpha subunits. As with Dalpha4 and Dalpha6, the Anopheles orthologues are alternatively spliced at equivalent exons. Reverse transcription-polymerase chain reaction analysis shows that RNA A-to-I editing sites conserved between Dalpha6 of Drosophila and alpha7-2 of the tobacco budworm, Heliothis virescens, are not shared with the equivalent nAChR subunit of Anopheles. Indeed, RNA-editing sites identified in functionally significant regions of Dbeta1, Dalpha5, and Dalpha6 are not conserved in the mosquito orthologues, indicating considerable divergence of RNA molecules targeted for editing within the insect order Diptera. These findings shed further light on the diversity of nAChR subunits and may present a useful basis for the development of improved malaria control agents by enhancing our understanding of a validated mosquito insecticide target.

  1. Nicotinic Acid Increases Adiponectin Secretion from Differentiated Bovine Preadipocytes through G-Protein Coupled Receptor Signaling

    Directory of Open Access Journals (Sweden)

    Christina Kopp

    2014-11-01

    Full Text Available The transition period in dairy cows (3 weeks prepartum until 3 weeks postpartum is associated with substantial mobilization of energy stores, which is often associated with metabolic diseases. Nicotinic acid (NA is an antilipolytic and lipid-lowering compound used to treat dyslipidaemia in humans, and it also reduces non-esterified fatty acids in cattle. In mice the G-protein coupled receptor 109A (GPR109A ligand NA positively affects the secretion of adiponectin, an important modulator of glucose and fat metabolism. In cattle, the corresponding data linking NA to adiponectin are missing. Our objective was to examine the effects of NA on adiponectin and AMPK protein abundance and the expression of mRNAs of related genes such as chemerin, an adipokine that enhances adiponectin secretion in vitro. Differentiated bovine adipocytes were incubated with pertussis toxin (PTX to verify the involvement of GPR signaling, and treated with 10 or 15 µM NA for 12 or 24 h. NA increased adiponectin concentrations (p ≤ 0.001 and the mRNA abundances of GPR109A (p ≤ 0.05 and chemerin (p ≤ 0.01. Pre-incubation with PTX reduced the adiponectin response to NA (p ≤ 0.001. The NA-stimulated secretion of adiponectin and the mRNA expression of chemerin in the bovine adipocytes were suggestive of GPR signaling-dependent improved insulin sensitivity and/or adipocyte metabolism in dairy cows.

  2. 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.

  3. Nitrogen substitution modifies the activity of cytisine on neuronal nicotinic receptor subtypes.

    Science.gov (United States)

    Carbonnelle, Eric; Sparatore, Fabio; Canu-Boido, Caterina; Salvagno, Cristian; Baldani-Guerra, Barbara; Terstappen, Georg; Zwart, Ruud; Vijverberg, Henk; Clementi, Francesco; Gotti, Cecilia

    2003-06-20

    Cytisine very potently binds and activates the alpha 3 beta 4 and alpha 7 nicotinic subtypes, but only partially agonises the alpha 4 beta 2 subtype. Although with a lower affinity than cytisine, new cytisine derivatives with different substituents on the basic nitrogen (CC1-CC8) bind to both the heteromeric and homomeric subtypes, with higher affinity for brain [3H]epibatidine receptors. The cytisine derivatives were tested on the Ca(2+) flux of native or transfected cell lines expressing the rat alpha 7, or human alpha 3 beta 4 or alpha 4 beta 2 subtypes using Ca(2+) dynamics in conjunction with a fluorescent image plate reader. None elicited any response at doses of up to 30-100 microM, but all inhibited agonist-induced responses. Compounds CC5 and CC7 were also electrophysiologically tested on oocyte-expressed rat alpha 4 beta 2, alpha 3 beta 4 and alpha 7 subtypes. CC5 competitively antagonised the alpha 4 beta 2 and alpha 3 beta 4 subtypes with similar potency, whereas CC7 only partially agonised them with maximum responses of respectively 3% and 11% of those of 1 mM acetylcholine. Neither compound induced any current in the oocyte-expressed alpha 7 subtype, and both weakly inhibited acetylcholine-induced currents. Adding chemical groups of a different class or size to the basic nitrogen of cytisine leads to compounds that lose full agonist activity on the alpha 3 beta 4 and alpha 7 subtypes.

  4. 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.

  5. Nicotinic Acetylcholine Receptor α4 Subunit Gene Variation Associated with Attention Deficit Hyperactivity Disorder

    Institute of Scientific and Technical Information of China (English)

    HUANG Xuezhu; XU Yong; LI Qianqian; LIU Pozi; YANG Yuan; ZHANG Fuquan; GUO Tianyou; YANG Chuang; GUO Lanting

    2009-01-01

    Previous pharmacological, human genetics, and animal models have implicated the nicotinic ace-tylcholine receptor a4 subunit (CHRNA4) gene in the pathogenesis of attention deficit/hyperactivity disorder (ADHD). The objective of this study is to examine the genetic association between single nucleotide poly-morphisms in the CHRNA4 gene (rs2273502, rs1044396, rs1044397, and rs3827020 loci) and ADHD. Both case-control and family-based designs are used. Children aged 6 to 16 years were interviewed and as-sessed with the children behavior checklist and the revised conner' parent rating scale to identify probands. No significant differences in the frequency distribution of genotypes or alleles were found between the case and control groups. However, further haplotype analyses showed the CCGG haplotype on dsk for ADHD in 164 case-control samples and the standard transmission disequilibrium test analyses suggest that the allele C of rs2273502 was over-transferred in 98 ADHD parent-offspring tdos. These findings suggest that the CHRNA4 gene may play a role in the pathogenesis of ADHD.

  6. A D-peptide ligand of nicotine acetylcholine receptors for brain-targeted drug delivery.

    Science.gov (United States)

    Wei, Xiaoli; Zhan, Changyou; Shen, Qing; Fu, Wei; Xie, Cao; Gao, Jie; Peng, Chunmei; Zheng, Ping; Lu, Weiyue

    2015-03-01

    Lysosomes of brain capillary endothelial cells are implicated in nicotine acetylcholine receptor (nAChR)-mediated transcytosis and act as an enzymatic barrier for the transport of peptide ligands to the brain. A D-peptide ligand of nAChRs (termed (D)CDX), which binds to nAChRs with an IC50 value of 84.5 nM, was developed by retro-inverso isomerization. (D)CDX displayed exceptional stability in lysosomal homogenate and serum, and demonstrated significantly higher transcytosis efficiency in an in vitro blood-brain barrier monolayer compared with the parent L-peptide. When modified on liposomal surface, (D)CDX facilitated significant brain-targeted delivery of liposomes. As a result, brain-targeted delivery of (D)CDX modified liposomes enhanced therapeutic efficiency of encapsulated doxorubicin for glioblastoma. This study illustrates the importance of ligand stability in nAChRs-mediated transcytosis, and paves the way for developing stable brain-targeted entities.

  7. 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

  8. Sensory gating and alpha-7 nicotinic receptor gene allelic variants in schizoaffective disorder, bipolar type.

    Science.gov (United States)

    Martin, Laura F; Leonard, Sherry; Hall, Mei-Hua; Tregellas, Jason R; Freedman, Robert; Olincy, Ann

    2007-07-05

    Single nucleotide allelic variants in the promoter region of the chromosome 15 alpha-7 acetylcholine nicotinic receptor gene (CHRNA7) are associated with both schizophrenia and the P50 auditory evoked potential sensory gating deficit. The purpose of this study was to determine if CHRNA7 promoter allelic variants are also associated with abnormal P50 ratios in persons with schizoaffective disorder, bipolar type. P50 auditory evoked potentials were recorded in a paired stimulus paradigm in 17 subjects with schizoaffective disorder, bipolar type. The P50 test to conditioning ratio was used as the measure of sensory gating. Mutation screening of the CHRNA7 promoter region was performed on the subjects' DNA samples. Comparisons to previously obtained data from persons with schizophrenia and controls were made. Subjects with schizophrenia, regardless of allele status, had an abnormal mean P50 ratio. Subjects with schizoaffective disorder, bipolar type and a variant allele had an abnormal mean P50 ratio, whereas those schizoaffective subjects with the common alleles had a normal mean P50 ratio. Normal control subjects had a normal mean ratio, but controls with variant alleles had higher P50 ratios. In persons with bipolar type schizoaffective disorder, CHRNA7 promoter region allelic variants are linked to the capacity to inhibit the P50 auditory evoked potential and thus are associated with a type of illness genetically and biologically more similar to schizophrenia.

  9. Structural correlates of affinity in fetal versus adult endplate nicotinic receptors

    Science.gov (United States)

    Nayak, Tapan Kumar; Chakraborty, Srirupa; Zheng, Wenjun; Auerbach, Anthony

    2016-04-01

    Adult-type nicotinic acetylcholine receptors (AChRs) mediate signalling at mature neuromuscular junctions and fetal-type AChRs are necessary for proper synapse development. Each AChR has two neurotransmitter binding sites located at the interface of a principal and a complementary subunit. Although all agonist binding sites have the same core of five aromatic amino acids, the fetal site has ~30-fold higher affinity for the neurotransmitter ACh. Here we use molecular dynamics simulations of adult versus fetal homology models to identify complementary-subunit residues near the core that influence affinity, and use single-channel electrophysiology to corroborate the results. Four residues in combination determine adult versus fetal affinity. Simulations suggest that at lower-affinity sites, one of these unsettles the core directly and the others (in loop E) increase backbone flexibility to unlock a key, complementary tryptophan from the core. Swapping only four amino acids is necessary and sufficient to exchange function between adult and fetal AChRs.

  10. Functional nicotinic acetylcholine receptor reconstitution in Au(111)-supported thiolipid monolayers

    Science.gov (United States)

    Pissinis, Diego E.; Diaz, Carolina; Maza, Eliana; Bonini, Ida C.; Barrantes, Francisco J.; Salvarezza, Roberto C.; Schilardi, Patricia L.

    2015-09-01

    The insertion and function of the muscle-type nicotinic acetylcholine receptor (nAChR) in Au(111)-supported thiolipid self-assembled monolayers have been studied by atomic force microscopy (AFM), surface plasmon resonance (SPR), and electrochemical techniques. It was possible for the first time to resolve the supramolecular arrangement of the protein spontaneously inserted in a thiolipid monolayer in an aqueous solution. Geometric supramolecular arrays of nAChRs were observed, most commonly in a triangular form compatible with three nAChR dimers of ~20 nm each. Addition of the full agonist carbamoylcholine activated and opened the nAChR ion channel, as revealed by the increase in capacitance relative to that of the nAChR-thiolipid system under basal conditions. Thus, the self-assembled system appears to be a viable biomimetic model to measure ionic conductance mediated by ion-gated ion channels under different experimental conditions, with potential applications in biotechnology and pharmacology.

  11. Functional interaction of nicotinic acetylcholine receptors and Na+/K+ ATPase from Locusta migratoria manilensis (Meyen).

    Science.gov (United States)

    Bao, Haibo; Sun, Huahua; Xiao, Youxin; Zhang, Yixi; Wang, Xin; Xu, Xiaoyong; Liu, Zewen; Fang, Jichao; Li, Zhong

    2015-03-06

    Associated proteins are important for the correct functioning of nicotinic acetylcholine receptors (nAChRs). In the present study, a neonicotinoid-agarose affinity column was used to isolate related proteins from a solubilized membrane preparation from the nervous system of Locusta migratoria manilensis (Meyen). 1530 peptides were identified and most of them were involved in the membranous structure, molecular interaction and cellular communication. Among these peptides, Na(+)/K(+) ATPase had the highest MASCOT score and were involved in the molecular interaction, which suggested that Na(+)/K(+) ATPase and nAChRs might have strong and stable interactions in insect central nervous system. In the present study, functional interactions between nAChRs and Na(+)/K(+) ATPase were examined by heterologous expression in Xenopus oocytes. The results showed that the activated nAChRs increased pump currents of Na(+)/K(+) ATPase, which did not require current flow through open nAChRs. In turn, Na(+)/K(+) ATPase significantly increased agonist sensitivities of nAChRs in a pump activity-independent manner and reduced the maximum current (Imax) of nAChRs. These findings provide novel insights concerning the functional interactions between insect nAChRs and Na(+)/K(+) ATPase.

  12. Modelling packing interactions in parallel helix bundles: pentameric bundles of nicotinic receptor M2 helices.

    Science.gov (United States)

    Sankararamakrishnan, R; Sansom, M S

    1995-11-01

    The transbilayer pore of the nicotinic acetylcholine receptor (nAChR) is formed by a pentameric bundle of M2 helices. Models of pentameric bundles of M2 helices have been generated using simulated annealing via restrained molecular dynamics. The influence of: (a) the initial C alpha template; and (b) screening of sidechain electrostatic interactions on the geometry of the resultant M2 helix bundles is explored. Parallel M2 helices, in the absence of sidechain electrostatic interactions, pack in accordance with simple ridges-in-grooves considerations. This results in a helix crossing angle of ca. +12 degrees, corresponding to a left-handed coiled coil structure for the bundle as a whole. Tilting of M2 helices away from the central pore axis at their C-termini and/or inclusion of sidechain electrostatic interactions may perturb such ridges-in-grooves packing. In the most extreme cases right-handed coiled coils are formed. An interplay between inter-helix H-bonding and helix bundle geometry is revealed. The effects of changes in electrostatic screening on the dimensions of the pore mouth are described and the significance of these changes in the context of models for the nAChR pore domain is discussed.

  13. Kinked structures of isolated nicotinic receptor M2 helices: a molecular dynamics study.

    Science.gov (United States)

    Sankararamakrishnan, R; Samsom, M S

    1994-12-01

    The pore-lining M2 helix of the nicotinic acetylcholine receptor exhibits a pronounced kink when the corresponding ion channel is in a closed conformation [N. Unwin (1993) Journal of Molecular Biology, Vol. 229, pp. 1101-1124]. We have performed molecular dynamics simulations of isolated 22-residue M2 helices in order to identify a possible molecular origin of this kink. In order to sample a wide range of conformational space, a simulated annealing protocol was used to generate five initial M2 helix structures, each of which was subsequently used as the basis of 300 ps MD simulations. Two helix sequences (M2 alpha and M2 delta) were studied in this manner, resulting in a total of ten 300 ps trajectories. Kinked helices present in the trajectories were identified and energy minimized to yield a total of five different stable kinked structures. For comparison, a similar molecular dynamics simulation of a Leu23 helix yielded no stable kinked structures. In four of the five kinked helices, the kink was stabilized by H bonds between the helix backbone and polar side-chain atoms. Comparison with data from the literature on site-directed mutagenesis of M2 residues suggests that such polar side-chain to main-chain H bonds may also contribute to kinking of M2 helices in the intact channel protein.

  14. Nereistoxin and cartap neurotoxicity attributable to direct block of the insect nicotinic receptor/channel.

    Science.gov (United States)

    Lee, Seog-Jong; Tomizawa, Motohiro; Casida, John E

    2003-04-23

    Nereistoxin (NTX) (4-dimethylamino-1,2-dithiolane) is the naturally occurring prototype for cartap [the bis(thiocarbamate) derivative of the NTX dithiol], which is generally regarded as a proinsecticide reverting to NTX. The aim of this study is to define the target site(s) for dithiolanes and dithiol esters. The affinity of [(3)H]NTX was not suitable for binding assays with honeybee (Apis mellifera) head membranes. However, NTX and cartap are equally potent, direct-acting, and competitive displacers of [(3)H]thienylcyclohexylpiperidine binding at the noncompetitive blocker (NCB) site of the Apis nicotinic acetylcholine receptor (nAChR)/channel. NTX also binds at the Apis [(3)H]imidacloprid agonist site, but cartap does not. As candidate metabolic pathways, sequential N-desmethylation and S-oxidation of NTX progressively reduce its potency at the NCB site and toxicity to houseflies. A P450 inhibitor reduces the toxicity of NTX and enhances it with cartap. Surprisingly, cartap is not just a pro-NTX but instead directly induces inhibitory neurotoxicity by blocking the nAChR/channel, whereas NTX may have dual NCB and agonist targets.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Nicotinic Receptor Alpha7 Expression during Tooth Morphogenesis Reveals Functional Pleiotropy

    Science.gov (United States)

    Rogers, Scott W.; Gahring, Lorise C.

    2012-01-01

    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. PMID:22666322

  18. Computational determination of the binding mode of α-conotoxin to nicotinic acetylcholine receptor

    Science.gov (United States)

    Tabassum, Nargis; Yu, Rilei; Jiang, Tao

    2016-12-01

    Conotoxins belong to the large families of disulfide-rich peptide toxins from cone snail venom, and can act on a broad spectrum of ion channels and receptors. They are classified into different subtypes based on their targets. The α-conotoxins selectively inhibit the current of the nicotinic acetylcholine receptors. Because of their unique selectivity towards distinct nAChR subtypes, α-conotoxins become valuable tools in nAChR study. In addition to the X-ray structures of α-conotoxins in complex with acetylcholine-binding protein, a homolog of the nAChR ligand-binding domain, the high-resolution crystal structures of the extracellular domain of the α1 and α9 subunits are also obtained. Such structures not only revealed the details of the configuration of nAChR, but also provided higher sequence identity templates for modeling the binding modes of α-conotoxins to nAChR. This mini-review summarizes recent modeling studies for the determination of the binding modes of α-conotoxins to nAChR. As there are not crystal structures of the nAChR in complex with conotoxins, computational modeling in combination of mutagenesis data is expected to reveal the molecular recognition mechanisms that govern the interactions between α-conotoxins and nAChR at molecular level. An accurate determination of the binding modes of α-conotoxins on AChRs allows rational design of α-conotoxin analogues with improved potency or selectivity to nAChRs.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. A robust homogeneous binding assay for α4β2 nicotinic acetylcholine receptor

    Institute of Scientific and Technical Information of China (English)

    Xin HUI; Jie GAO; Xin XIE; Naoki SUTO; Tsuyoshi OGIKU; Ming-Wei WANG

    2005-01-01

    Aim: To develop a homogeneous high-throughput screening (HTS) assay based on scintillation proximity assay (SPA) technology for identification of novel α4β2 nicotinic acetylcholine receptor (nAChR) modulators. Methods: Membrane preparation of HEK293 cells expressing α4β2 nAChR, [3H]cytisine and wheat germ agglutinin (WGA)-coupled microbeads were used to develop an HTS assay based on SPA technology. This method was validated against a conventional filter binding approach and applied to large-scale screening of a library containing 32 000 synthetic compounds. Intracellular calcium measurement was carried out to verify the bioactivities of the hits found by the SPA assay. Results: IC50 values of 2 reference compounds (epibatidine and RJR 2403) determined by SPA and filter binding methods were comparable and consistent with those reported elsewhere. A total of 54 compounds, showing more than 60% competitive inhibition on [3H]cytisine binding to α4β2 nAChR, were identified initially following an HTS campaign. Secondary screening confirmed that 17 compounds with novel chemical structures possessed relatively high binding affinity to α4β2 nAChR (Ki<2 μmol/L). Eight compounds displayed antagonistic effects with >50% inhibition on ABT-594-induced calcium mobilization while none showed any agonist activity. Conclusions: This homogeneous binding assay is a highly efficient,amenable to automation and robust tool to screen potential α4β2 nAChR modulators in an HTS setting. Its application may be expanded to other membrane receptors and ion channels.

  1. Modes of action, resistance and toxicity of insecticides targeting nicotinic acetylcholine receptors.

    Science.gov (United States)

    Ihara, Makoto; Buckingham, Steven D; Matsuda, Kazuhiko; Sattelle, David B

    2017-02-06

    Nicotinic acetylcholine receptors (nAChRs) are members of the cys-loop superfamily of ligand-gated ion channels (cys-loop LGICs) and mediate fast cholinergic synaptic transmission in the nervous system of insects. The completion of many insect genome projects has greatly enhanced our understanding of the individual subunits that make up nAChR gene families from an insect genetic model organism (Drosophila melanogaster), crop pests, disease vectors and beneficial (pollinator) species. In addition to considerable insect nAChR subunit diversity, individual subunits can be subject to alternative splicing and RNA editing and these post-transcriptional modifications can add significantly to the diversity of nAChR receptor subtypes. The actions of insecticides targeting nAChRs, notably cartap, neonicotinoids, sulfoximines, flupyradifurone, spinosyns and triflumezopyrim are reviewed. Structural studies obtained using an acetylcholine binding protein (AChBP) co-crystallised with neonicotinoids have yielded important new insights into the requirements for neonicotinoid insecticide - nAChR interactions. The persistent application of insecticides to crop pests leads to the onset of resistance and several examples of resistance to insecticides targeting nAChRs have been documented. Understanding the molecular basis of resistance can inform our understanding of the mechanism of insecticide action. It also provides an important driver for the development of new chemistry, diagnostic tests for resistance and the adoption of application strategies designed to attenuate such problems. Finally, we consider toxicity issues relating to nAChR-active insecticides, with particular reference to beneficial insect species (pollinators) as well as mammalian and avian toxicity. This review is part of the special issue "Insecticide Mode of Action: From Insect to Mammalian Toxicity.".

  2. 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.

  3. 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....

  4. Nicotine Dependence

    Science.gov (United States)

    Nicotine dependence Overview By Mayo Clinic Staff Nicotine dependence ― also called tobacco dependence ― is an addiction to tobacco products caused by the drug nicotine. Nicotine dependence means you can't stop using the substance, ...

  5. Postsynaptic action of brain-derived neurotrophic factor attenuates alpha7 nicotinic acetylcholine receptor-mediated responses in hippocampal interneurons.

    Science.gov (United States)

    Fernandes, Catarina C; Pinto-Duarte, António; Ribeiro, Joaquim Alexandre; Sebastião, Ana M

    2008-05-21

    Nicotinic mechanisms acting on the hippocampus influence attention, learning, and memory and constitute a significant therapeutic target for many neurodegenerative, neurological, and psychiatric disorders. Here, we report that brain-derived neurotrophic factor (BDNF) (1-100 ng/ml), a member of the neurotrophin gene family, rapidly decreases alpha7 nicotinic acetylcholine receptor responses in interneurons of the hippocampal CA1 stratum radiatum. Such effect is dependent on the activation of the TrkB receptor and involves the actin cytoskeleton; noteworthy, it is compromised when the extracellular levels of the endogenous neuromodulator adenosine are reduced with adenosine deaminase (1 U/ml) or when adenosine A(2A) receptors are blocked with SCH 58261 (2-(2-furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine) (100 nm). The intracellular application of U73122 (1-[6[[(17beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione) (5 mum), a broad-spectrum inhibitor of phospholipase C, or GF 109203X (bisindolylmaleimide I) (2 mum), a general inhibitor of protein kinase C isoforms, blocks BDNF-induced inhibition of alpha7 nicotinic acetylcholine receptor function. Moreover, in conditions of simultaneous intracellular dialysis of the fast Ca(2+) chelator BAPTA (10 mm) and removal of extracellular Ca(2+) ions, the inhibitory action of BDNF is further prevented. The present findings disclose a novel target for rapid actions of BDNF that might play important roles on synaptic transmission and plasticity in the brain.

  6. Pre-clinical properties of the α4β2 nicotinic acetylcholine receptor partial agonists varenicline, cytisine and dianicline translate to clinical efficacy for nicotine dependence

    Science.gov (United States)

    Rollema, H; Shrikhande, A; Ward, KM; Tingley, FD; Coe, JW; O'Neill, BT; Tseng, E; Wang, EQ; Mather, RJ; Hurst, RS; Williams, KE; de Vries, M; Cremers, T; Bertrand, S; Bertrand, D

    2010-01-01

    Background and purpose: Smoking cessation trials with three high-affinity partial agonists of α4β2 neuronal nicotinic acetylcholine receptors (nAChRs) have demonstrated differences in their clinical efficacy. This work examines the origin of the differences by taking into account brain exposure and pharmacological effects at human α4β2 nAChRs. Experimental approach: Rat plasma and brain pharmacokinetics were characterized and used to predict human steady-state plasma and brain concentrations following recommended doses of each of the three compounds. The pharmacological characterization included in vitro affinities at different nAChR subtypes, functional efficacies and potencies at the human α4β2 nAChR, as well as in vivo effects on rat mesolimbic dopamine turn-over. Key results: A comparison of predicted human brain concentrations following therapeutic doses demonstrated that varenicline and nicotine, but not dianicline and cytisine, can extensively desensitize and, to a lesser extent, activate α4β2 nAChRs. The limited clinical efficacy of dianicline may be accounted for by a combination of weak functional potency at α4β2 nAChRs and moderate brain penetration, while recommended doses of cytisine, despite its high in vitro potency, are predicted to result in brain concentrations that are insufficient to affect α4β2 nAChRs. Conclusions and implications: The data provide a plausible explanation for the higher abstinence rate in smoking cessation trials following treatment with varenicline than with the two other α4β2 nAChR partial agonists. In addition, this retrospective analysis demonstrates the usefulness of combining in vitro and in vivo parameters with estimated therapeutic human brain concentrations for translation to clinical efficacy. PMID:20331614

  7. Nicotinic cholinergic receptors in esophagus: Early alteration during carcinogenesis and prognostic value

    Science.gov (United States)

    Chianello Nicolau, Marina; Pinto, Luis Felipe Ribeiro; Nicolau-Neto, Pedro; de Pinho, Paulo Roberto Alves; Rossini, Ana; de Almeida Simão, Tatiana; Soares Lima, Sheila Coelho

    2016-01-01

    AIM To compare expression of nicotinic cholinergic receptors (CHRNs) in healthy and squamous cell carcinoma-affected esophagus and determine the prognostic value. METHODS We performed RT-qPCR to measure the expression of CHRNs in 44 esophageal samples from healthy individuals and in matched normal surrounding mucosa, and in tumors from 28 patients diagnosed with esophageal squamous cell carcinoma (ESCC). Next, we performed correlation analysis for the detected expression of these receptors with the habits and clinico-pathological characteristics of all study participants. In order to investigate the possible correlations between the expression of the different CHRN subunits in both healthy esophagus and tissues from ESCC patients, correlation matrices were generated. Subsequently, we evaluated whether the detected alterations in expression of the various CHRNs could precede histopathological modifications during the esophageal carcinogenic processes by using receiver operating characteristic curve analysis. Finally, we evaluated the impact of CHRNA5 and CHRNA7 expression on overall survival by using multivariate analysis. RESULTS CHRNA3, CHRNA5, CHRNA7 and CHRNB4, but not CHRNA1, CHRNA4, CHRNA9 or CHRNA10, were found to be expressed in normal (healthy) esophageal mucosa. In ESCC, CHRNA5 and CHRNA7 were overexpressed as compared with patient-matched surrounding non-tumor mucosa (ESCC-adjacent mucosa; P < 0.0001 and P = 0.0091, respectively). Positive correlations were observed between CHRNA3 and CHRNB4 expression in all samples analyzed. Additionally, CHRNB4 was found to be differentially expressed in the healthy esophagus and the normal-appearing ESCC-adjacent mucosa, allowing for distinguishment between these tissues with a sensitivity of 75.86% and a specificity of 78.95% (P = 0.0002). Finally, CHRNA5 expression was identified as an independent prognostic factor in ESCC; patients with high CHRNA5 expression showed an increased overall survival, in comparison with

  8. Alternative splicing in nicotinic acetylcholine receptor subunits from Locusta migratoria and its influence on acetylcholine potencies.

    Science.gov (United States)

    Zhang, Yixi; Liu, Yang; Bao, Haibo; Sun, Huahua; Liu, Zewen

    2017-01-18

    Due to the great abundance within insect central nervous system (CNS), nicotinic acetylcholine receptors (nAChRs) play key roles in insect CNS, which makes it to be the targets of several classes of insecticides, such as neonicotinoids. Insect nAChRs are pentameric complexes consisting of five subunits, and a dozen subunits in one insect species can theoretically comprise diverse nAChRs. The alternative splicing in insect nAChR subunits may increase the diversity of insect nAChRs. In the oriental migratory locust (Locusta migratoria manilensis Meyen), a model insect species with agricultural importance, the alternative splicing was found in six α subunits among nine α and two β subunits, such as missing conserved residues in Loop D from Locα1, Locα6 and Locα9, a 34-residue insertion in Locα8 cytoplasmic loop, and truncated transcripts for Locα4, Locα7 and Locα9. Hybrid nAChRs were successfully constructed in Xenopus oocytes through co-expression with rat β2 and one α subunit from L. migratoria, which included Locα1, Locα2, Locα3, Locα4, Locα5, Locα8 and Locα9. Influences of alternative splicing in Locα1, Locα8 and Locα9 on acetylcholine potency were tested on hybrid nAChRs. The alternative splicing in Locα1 and Locα9 could increase acetylcholine sensitivities on recombinant receptors, while the splicing in Locα8 showed significant influences on the current amplitudes of oocytes. The results revealed that the alternative splicing at or close to the ligand-binding sites, as well as at cytoplasmic regions away from the ligand-binding sites, in insect nAChR subunits would change the agonist potencies on the receptors, which consequently increased nAChR diversity in functional and pharmacological properties.

  9. Non-competitive Inhibition of Nicotinic Acetylcholine Receptors by Ladybird Beetle Alkaloids.

    Science.gov (United States)

    Leong, Ron L; Xing, Hong; Braekman, Jean-Claude; Kem, William R

    2015-10-01

    Ladybird beetles (Family Coccinellidae) secrete an alkaloid rich venom from their leg joints that protects them from predators. Coccinellines, the major venom constituents, are alkaloids composed of three fused piperidine rings that share a common nitrogen atom. Although many coccinellines have been isolated and chemically characterized, their pharmacological properties are essentially unknown. Using radioligand binding and functional assays we investigated the actions of several coccinellines on skeletal muscle and α7 nicotinic acetylcholine receptors (nAChRs). The alkaloids were shown to displace the specific binding of tritiated piperidyl-N-(1-(2-thienyl)cyclohexyl)-3,4-piperidine ([(3)H]-TCP), which has been shown to bind deep within the ion channel of the electric fish (Torpedo) muscle nAChR. The stereoisomers precoccinelline and hippodamine (whose nitrogens are predicted to be ionized at physiological pH) and their respective analogs N-methyl-precoccinelline and N-methyl-hippodamine (whose quaternary nitrogens are permanently charged) displayed similar IC50s for inhibition of [(3)H]-TCP binding. However, the corresponding precoccinelline and hippodamine N-oxides, coccinelline and convergine (which have an electronegative oxygen bonded to an electropositive nitrogen) displayed significantly higher binding IC50s. Finally, exochomine, a dimeric coccinelline containing the hippodamine structure, displayed the highest IC50 (lowest affinity) for displacing specific [(3)H]-TCP binding. The presence of a desensitizing concentration (10(-3) M) of carbachol (CCh) had little or no effect on the affinity of the Torpedo nAChR for the three coccinellines tested. High concentrations of the coccinellid alkaloids did not affect binding of [(3)H]-cytisine to Torpedo receptor ACh binding sites. Inhibition of the alpha7 nAChR with pre-equilibrated precoccinelline was insurmountable with respect to ACh concentration. We conclude that the coccinellines bind to one or more

  10. Prolonged nicotine exposure down-regulates presynaptic NMDA receptors in dopaminergic terminals of the rat nucleus accumbens.

    Science.gov (United States)

    Salamone, Alessia; Zappettini, Stefania; Grilli, Massimo; Olivero, Guendalina; Agostinho, Paula; Tomé, Angelo R; Chen, Jiayang; Pittaluga, Anna; Cunha, Rodrigo A; Marchi, Mario

    2014-04-01

    The presynaptic control of dopamine release in the nucleus accumbens (NAc) by glutamate and acetylcholine has a profound impact on reward signaling. Here we provide immunocytochemical and neurochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs) and N-methyl-D-aspartic acid (NMDA) receptors in dopaminergic terminals of the NAc. Most NAc dopaminergic terminals possessed the nAChR α4 subunit and the pre-exposure of synaptosomes to nicotine (30 μM) or to the α4β2-containing nAChR agonist 5IA85380 (10 nM) selectively inhibited the NMDA (100 μM)-evoked, but not the 4-aminopyridine (10 μM)-evoked, [(3)H] dopamine outflow; this inhibition was blunted by mecamylamine (10 μM). Nicotine and 5IA85380 pretreatment also inhibited the NMDA (100 μM)-evoked increase of calcium levels in single nerve terminals, an effect prevented by dihydro-β-erythroidine (1 μM). This supports a functional interaction between α4β2-containing nAChR and NMDA receptors within the same terminal, as supported by the immunocytochemical co-localization of α4 and GluN1 subunits in individual NAc dopaminergic terminals. The NMDA-evoked [(3)H]dopamine outflow was blocked by MK801 (1 μM) and inhibited by the selective GluN2B-selective antagonists ifenprodil (1 μM) and RO 25-6981 (1 μM), but not by the GluN2A-preferring antagonists CPP-19755 (1 μM) and ZnCl2 (1 nM). Notably, nicotine pretreatment significantly decreased the density of biotin-tagged GluN2B proteins in NAc synaptosomes. These results show that nAChRs dynamically and negatively regulate NMDA receptors in NAc dopaminergic terminals through the internalization of GluN2B receptors.

  11. Progess in mechanism of nicotinic acid mediated by nicotinic acid receptor GPR109A%烟酸受体GPR109A介导的烟酸作用机制研究进展

    Institute of Scientific and Technical Information of China (English)

    黄燕; 刘培庆

    2012-01-01

    Nicotinic acid (niacin) has been used for the treatment of lipid disorders for more than fifty years and relatively high doses of nicotinic acid induces profound change in the lipid and lipoprotein profile. There is increasing evidence that nicotinic acid alone or in addition to LDL cholesterol-lowering drugs can improve the progression of atherosclerosis and reduce the risk of cardiovascular events; but the mechanisms underlying the pharmacological effects of nicotinic acid have been unclear for decades. The discovery of nicotinic acid receptors in 2003 by 3 research groups has allowed for better understanding of the machanisms of nicotinic acid. Nicotinic acid receptor GPR109A is an Gi-coupled receptor, highly expressed in white and brown adipose tissue, spleen and immune cells. New findings indicated that nicotinic acid receptor induced the following: ① in adipose, nicotinic acid agonized the receptor inhibiting triglyceride hydrolysis to lower plasma free fatty acids (FFA) level; ② nicotinic acid provoked the receptor of keratinocytes and Langerhans cells of skin to produce prostaglandin, dilating vascellum of skin, initiating flushing; ③ the activation of nicotinic acid receptor enhanced adiponectin secretion, induced neutrophils apoptosis, and upregulated the expression of PPARgamma.%烟酸作为调脂药物应用于临床已经50多年,相对高剂量的烟酸具有广泛的调脂作用.越来越多的证据表明,烟酸单用或联合降低低密度脂蛋白胆固醇( LDL-C)药物使用能够延缓动脉粥样硬化(AS)的进程和降低发生心血管事件的风险;但它的作用机制一直不是很明确.2003年,三个研究小组同时发现了烟酸受体,使人们对烟酸的作用机制有了进一步认识.烟酸受体GPR109A是一种Gi蛋白偶联受体,主要表达于白色、棕色脂肪组织、脾和免疫细胞.研究表明,烟酸受体主要介导以下作用:①烟酸作用于脂肪细胞的烟酸受体,抑制脂肪组

  12. Early Signs of Pathological Cognitive Aging in Mice Lacking High-Affinity Nicotinic Receptors.

    Science.gov (United States)

    Konsolaki, Eleni; Tsakanikas, Panagiotis; Polissidis, Alexia V; Stamatakis, Antonios; Skaliora, Irini

    2016-01-01

    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. A 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 behavioral 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 behaviors, such as species-specific activities and exploration/locomotion in a novel environment. Our data confirm the hypothesis that β2-/- animals exhibit age-related cognitive impairments in spatial learning. In addition, they document age-related deficits in other areas, such as recognition memory, burrowing and nesting building, thereby extending the validity of this animal model for the study of pathological aging. Finally, our data reveal deficits in spontaneous behavior and habituation processes that precede the onset of cognitive decline and could therefore be useful as a non-invasive behavioral screen for identifying animals at risk. To our knowledge, this is the first study to perform an extensive behavioral assessment of an animal model of premature cognitive aging, and our results suggest that β2-nAChR dependent cognitive deterioration progressively evolves from initial subtle behavioral changes to global dementia due to the combined effect of the neuropathology and aging.

  13. Acetylcholine elongates neuronal growth cone filopodia via activation of nicotinic acetylcholine receptors.

    Science.gov (United States)

    Zhong, Lei Ray; Estes, Stephen; Artinian, Liana; Rehder, Vincent

    2013-07-01

    In addition to acting as a classical neurotransmitter in synaptic transmission, acetylcholine (ACh) has been shown to play a role in axonal growth and growth cone guidance. What is not well understood is how ACh acts on growth cones to affect growth cone filopodia, structures known to be important for neuronal pathfinding. We addressed this question using an identified neuron (B5) from the buccal ganglion of the pond snail Helisoma trivolvis in cell culture. ACh treatment caused pronounced filopodial elongation within minutes, an effect that required calcium influx and resulted in the elevation of the intracellular calcium concentration ([Ca]i ). Whole-cell patch clamp recordings showed that ACh caused a reduction in input resistance, a depolarization of the membrane potential, and an increase in firing frequency in B5 neurons. These effects were mediated via the activation of nicotinic acetylcholine receptors (nAChRs), as the nAChR agonist dimethylphenylpiperazinium (DMPP) mimicked the effects of ACh on filopodial elongation, [Ca]i elevation, and changes in electrical activity. Moreover, the nAChR antagonist tubucurarine blocked all DMPP-induced effects. Lastly, ACh acted locally at the growth cone, because growth cones that were physically isolated from their parent neuron responded to ACh by filopodial elongation with a similar time course as growth cones that remained connected to their parent neuron. Our data revealed a critical role for ACh as a modulator of growth cone filopodial dynamics. ACh signaling was mediated via nAChRs and resulted in Ca influx, which, in turn, caused filopodial elongation.

  14. 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.

  15. Subchronic nicotine exposure in adolescence induces long-term effects on hippocampal and striatal cannabinoid-CB1 and mu-opioid receptors in rats.

    Science.gov (United States)

    Marco, Eva M; Granstrem, Oleg; Moreno, Enrique; Llorente, Ricardo; Adriani, Walter; Laviola, Giovanni; Viveros, Maria-Paz

    2007-02-14

    There is evidence for the existence of functional interactions between nicotine and cannabinoids and opioid compounds in adult experimental animals. However, there is scarce information about these relationships in young animals. In the present study we evaluated short and long-term effects of a subchronic nicotine treatment [0.4 mg/kg daily i.p. injections from postnatal day (PND) 34 to PND 43], upon hippocampal and striatal cannabinoid-CB(1) and mu-opioid receptors in Wistar rats of both genders. Rats were sacrificed 2 h after the last nicotine injection (short-term effects, PND 43) or one month later (long-term effects, PND 75). Hippocampal and striatal cannabinoid CB(1) and mu-opioid receptors were quantified by Western blotting. The subchronic nicotine treatment induced a region-dependent long-lasting effect in cannabinoid CB(1) receptor: a significant increase in hippocampal cannabinoid CB(1) receptors and a significant decrease in striatal cannabinoid CB(1) receptors, with these effects being similar in males and females. With respect to mu-opioid receptors, subchronic nicotine induced a significant down-regulation in hippocampal and striatal mu-opioid receptors in the long-term, and within the striatum the effects were more marked in adult males than in females. The present results indicate that juvenile nicotine taking may have implications for the endocannabinoid and endogenous opioid function and for the behaviors served by those systems, this includes possible modification of the response of adults to different psychotropic drugs, i.e. cannabis and morphine/heroin when taken later in life.

  16. Prefrontal beta2 subunit-containing and alpha7 nicotinic acetylcholine receptors differentially control glutamatergic and cholinergic signaling.

    Science.gov (United States)

    Parikh, Vinay; Ji, Jinzhao; Decker, Michael W; Sarter, Martin

    2010-03-03

    One-second-long increases in prefrontal cholinergic activity ("transients") were demonstrated previously to be necessary for the incorporation of cues into ongoing cognitive processes ("cue detection"). Nicotine and, more robustly, selective agonists at alpha4beta2* nicotinic acetylcholine receptors (nAChRs) enhance cue detection and attentional performance by augmenting prefrontal cholinergic activity. The present experiments determined the role of beta2-containing and alpha7 nAChRs in the generation of prefrontal cholinergic and glutamatergic transients in vivo. Transients were evoked by nicotine, the alpha4beta2* nAChR agonist ABT-089 [2-methyl-3-(2-(S)-pyrrolindinylmethoxy) pyridine dihydrochloride], or the alpha7 nAChR agonist A-582941 [2-methyl-5-(6-phenyl-pyridazin-3-yl)-octahydro-pyrrolo[3,4-c]pyrrole]. Transients were recorded in mice lacking beta2 or alpha7 nAChRs and in rats after removal of thalamic glutamatergic or midbrain dopaminergic inputs to prefrontal cortex. The main results indicate that stimulation of alpha4beta2* nAChRs evokes glutamate release and that the presence of thalamic afferents is necessary for the generation of cholinergic transients. ABT-089-evoked transients were completely abolished in mice lacking beta2* nAChRs. The amplitude, but not the decay rate, of nicotine-evoked transients was reduced by beta2* knock-out. Conversely, in mice lacking the alpha7 nAChR, the decay rate, but not the amplitude, of nicotine-evoked cholinergic and glutamatergic transients was attenuated. Substantiating the role of alpha7 nAChR in controlling the duration of release events, stimulation of alpha7 nAChR produced cholinergic transients that lasted 10- to 15-fold longer than those evoked by nicotine. alpha7 nAChR-evoked cholinergic transients are mediated in part by dopaminergic activity. Prefrontal alpha4beta2* nAChRs play a key role in evoking and facilitating the transient glutamatergic-cholinergic interactions that are necessary for cue detection

  17. Effects of nicotinic acetylcholine receptor agonists in assays of acute pain-stimulated and pain-depressed behaviors in rats.

    Science.gov (United States)

    Freitas, Kelen C; Carroll, F Ivy; Negus, S Stevens

    2015-11-01

    Agonists at nicotinic acetylcholine receptors (nAChRs) constitute one drug class being evaluated as candidate analgesics. Previous preclinical studies have implicated α4β2 and α7 nAChRs as potential mediators of the antinociceptive effects of (–)-nicotine hydrogen tartrate (nicotine) and other nAChR agonists; however, these studies have relied exclusively on measures of pain-stimulated behavior, which can be defined as behaviors that increase in frequency, rate, or intensity after presentation of a noxious stimulus. Pain is also associated with depression of many behaviors, and drug effects can differ in assays of pain-stimulated versus pain-depressed behavior. Accordingly, this study compared the effects of nicotine, the selective α4/6β2 agonist 5-(123I)iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380), and the selective α7 agonist N-(3R)-1-azabicyclo(2.2.2)oct-3-yl-4-chlorobenzamide in assays of pain-stimulated and pain-depressed behavior in male Sprague-Dawley rats. Intraperitoneal injection of dilute lactic acid served as an acute noxious stimulus to either stimulate a stretching response or depress the operant responding, which is maintained by electrical brain stimulation in an intracranial self-stimulation (ICSS) procedure. Nicotine produced a dose-dependent, time-dependent, and mecamylamine-reversible blockade of both acid-stimulated stretching and acid-induced depression of ICSS. 5-I-A-85380 also blocked both acid-stimulated stretching and acid-induced depression of ICSS, whereas N-(3R)-1-azabicyclo(2.2.2)oct-3-yl-4-chlorobenzamide produced no effect in either procedure. Both nicotine and 5-I-A-85380 were ≥10-fold more potent in blocking the acid-induced depression of ICSS than in blocking the acid-induced stimulation of stretching. These results suggest that stimulation of α4β2 and/or α6β2 nAChRs may be especially effective to alleviate the signs of pain-related behavioral depression in rats; however, nonselective behavioral effects

  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. α4β2 nicotinic acetylcholine receptor partial agonists with low intrinsic efficacy have antidepressant-like properties

    Science.gov (United States)

    Mineur, Yann S.; Einstein, Emily B.; Seymour, Patricia A.; Coe, Jotham W.; O’Neill, Brian T.; Rollema, Hans

    2011-01-01

    Previous studies have suggested that treatment with antagonists or partial agonists of nicotinic acetylcholine receptors containing the β2 subunit (β2* nAChRs) results in antidepressant-like effects. In the current study we tested 3 novel compounds with different affinity and functional efficacy at α4β2* nAChRs, which were synthesized as part of nAChR discovery projects at Pfizer in the tail suspension, forced swim and novelty-suppressed feeding tests of antidepressant efficacy. All compounds tested reduced immobility in the forced swim test and one of the compounds also reduced immobility in the tail suspension test. All the compounds appeared to affect food intake on their own, with 2 compounds reducing feeding significantly in the home cage, precluding a clear interpretation of the results in the novelty-suppressed feeding test. None of the compounds altered locomotor activity at the doses and time points used here. Therefore, a subset of these compounds has pharmacological and behavioral properties that demonstrate the potential of nicotinic compounds as a treatment of mood disorders. Further development of nicotinic-based antidepressants should focus on increasing nAChR subtype selectivity to obtain consistent antidepressant properties with an acceptable side effect profile. PMID:21566524

  20. Facilitatory effect of dopamine on neuromuscular transmission mediated via dopamine D1-like receptors and prospective interaction with nicotine.

    Science.gov (United States)

    AlQot, H E; Elnozahi, N A; Mohy El-Din, M M; Bistawroos, A E; Abou Zeit-Har, M S

    2015-10-15

    The objective of this study is to probe the effects of dopamine and potential interactions with nicotine at the motor end plate. To accomplish this, we measured the amplitude of nerve-evoked muscle twitches of the isolated rat phrenic hemi-diaphragm preparation. Dopamine potentiated indirect muscle twitches in normal and gallamine-presensitized preparations amounting to a maximum of 31.14±0.71% and 69.23±1.96%, respectively. The dopamine-induced facilitation was well maintained in presence of 10 µM propranolol but greatly reduced in presence of 6 µM SCH 23390 or 3 µM dantrolene. In addition, SKF 81297 attained a plateau at 16 µM as opposed to 64 µM dopamine, with a percentage potentiation of 69.47±1.76. The facilitatory effect of dopamine was potentiated in nicotine treated rats. This study revealed for the first time that the facilitatory effect exerted by dopamine on neuromuscular transmission is mediated via the dopamine D1-like receptors. In addition, it highlighted the possible dependency of dopamine effects on intracellular calcium and signified potential interaction among dopamine and nicotine. Clinically, the findings generated by this study reveal potential targets for approaching motor deficit syndromes.

  1. 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.

  2. The Impact of Developmental Nicotine on Hippocampus-Dependent Memory: Evidence for a Critical Role of alpha2-Containing Nicotinic Acetylcholine Receptors

    OpenAIRE

    Kleeman, Elise

    2015-01-01

    Approximately 10 percent of the children born in the United States each year are exposed to cigarette smoke in utero, putting them at heightened risk for many physical and cognitive problems. Here we used mouse and rat models of early developmental nicotine exposure in order to elucidate the hippocampal changes that underlie nicotine-induced memory impairment. We observed that mice exposed to nicotine during their first two postnatal weeks showed significantly impaired long-term hippocampus-d...

  3. Kynurenic acid as an antagonist of α7 nicotinic acetylcholine receptors in the brain: facts and challenges.

    Science.gov (United States)

    Albuquerque, Edson X; Schwarcz, Robert

    2013-04-15

    Kynurenic acid (KYNA), a major tryptophan metabolite, is a glutamate receptor antagonist, which is also reported to inhibit α7 nicotinic acetylcholine receptors (α7nAChRs). Due to variations in experimental approaches, controversy has arisen regarding the ability of KYNA to directly influence α7nAChR function. Here we summarize current concepts of KYNA neurobiology and review evidence pertaining to the proposed role of KYNA as an endogenous modulator of α7nAChRs and synaptic transmission. As dysfunction of α7nAChRs plays a major role in the pathophysiology of central nervous system disorders, elucidation of KYNA's action on this receptor subtype has significant therapeutic implications.

  4. From α4β2 Nicotinic Ligands to the Discovery of σ1 Receptor Ligands: Pharmacophore Analysis and Rational Design.

    Science.gov (United States)

    Yu, Li-Fang; Zhang, Han-Kun; Gunosewoyo, Hendra; Kozikowski, Alan P

    2012-12-13

    Comparative analyses of the pharmacophoric elements required for σ1 and nicotinic ligands led to the identification of a potent and selective σ1 ligand (15). Compound 15 displayed high selectivity for the σ1 receptor (Ki, σ1 = 4.1 nM, Ki, σ2 = 1312 nM) with moderate binding affinity for the DAT (Ki = 373 nM) and NET (Ki = 203 nM) in the PDSP broad screening panel of common CNS neurotransmitter transporters and receptors. The key finding in this present work is that a subtle structural modifica tion could be used as a tool to switch a ligand's selectivity between nAChRs and sigma receptors.

  5. Mechanism-based medication development for the treatment of nicotine dependence

    Institute of Scientific and Technical Information of China (English)

    Zheng-xiong XI; Krista SPILLER; Eliot L GARDNER

    2009-01-01

    Tobacco use is a global problem with serious health consequences. Though some treatment options exist, there remains a great need for new effective pharmacotherapies to aid smokers in maintaining long-term abstinence. In the present article, we first discuss the neural mechanisms underlying nicotine reward, and then review various mechanism-based pharmacological agents for the treatment of nicotine dependence. An oversimplified hypothesis of addiction to tobacco is that nicotine is the major addictive component of tobacco. Nicotine binds to a4β2 and a7 nicotinic acetylcholine receptors (nAChRs) located on dopaminergic, glutamatergic and GABAergic neurons in the mesolimbic dopamine (DA) system, which causes an increase in extracellular DA in the nucleus accumbens (NAc). That increase in DA reinforces tobacco use, particularly during the acquisition phase. Enhanced glutamate transmission to DA neurons in the ventral tegmental area appears to play an important role in this process. In addition, chronic nicotine treatment increases endocannabinoid levels in the mesolimbic DA system, which indirectly modulates NAc DA release and nicotine reward. Accordingly, pharmacological agents that target brain acetylcholine, DA, glutamate, GABA, or endocannabonoid signaling systems have been proposed to interrupt nicotine action. Furthermore, pharmacokinetic strategies that alter plasma nicotine availability, metabolism and clearance also significantly alter nicotine's action in the brain. Progress using these pharmacodynamic and pharmacokinetic agents is reviewed. For drugs in each category, we discuss the mechanistic rationale for their potential anti-nicotine efficacy, major findings in preclinical and clinical studies, and future research directions.

  6. The potent M1 receptor allosteric agonist GSK1034702 improves episodic memory in humans in the nicotine abstinence model of cognitive dysfunction.

    Science.gov (United States)

    Nathan, Pradeep J; Watson, Jeannette; Lund, Jesper; Davies, Ceri H; Peters, Gary; Dodds, Chris M; Swirski, Bridget; Lawrence, Philip; Bentley, Graham D; O'Neill, Barry V; Robertson, Jon; Watson, Stephen; Jones, Gareth A; Maruff, Paul; Croft, Rodney J; Laruelle, Marc; Bullmore, Edward T

    2013-05-01

    Episodic memory deficits are a core feature of neurodegenerative disorders. Muscarinic M(1) receptors play a critical role in modulating learning and memory and are highly expressed in the hippocampus. We examined the effect of GSK1034702, a potent M(1) receptor allosteric agonist, on cognitive function, and in particular episodic memory, in healthy smokers using the nicotine abstinence model of cognitive dysfunction. The study utilized a randomized, double-blind, placebo-controlled, cross-over design in which 20 male nicotine abstained smokers were tested following single doses of placebo, 4 and 8 mg GSK1034702. Compared to the baseline (nicotine on-state), nicotine abstinence showed statistical significance in reducing immediate (p=0.019) and delayed (p=0.02) recall. GSK1034702 (8 mg) significantly attenuated (i.e. improved) immediate recall (p=0.014) but not delayed recall. None of the other cognitive domains was modulated by either nicotine abstinence or GSK1034702. These findings suggest that stimulating M(1) receptor mediated neurotransmission in humans with GSK1034702 improves memory encoding potentially by modulating hippocampal function. Hence, selective M(1) receptor allosteric agonists may have therapeutic benefits in disorders of impaired learning including Alzheimer's disease.

  7. 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.

  8. The novel Na+/Ca2+ exchange inhibitor KB-R7943 also blocks native and expressed neuronal nicotinic receptors

    Science.gov (United States)

    Pintado, Antonio J; Herrero, Carlos J; García, Antonio G; Montiel, Carmen

    2000-01-01

    We studied the effects of the novel Na+/Ca2+ exchange inhibitor KB-R7943, 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methanesulphonate, on the native nicotinic receptors present at the bovine adrenal chromaffin cells, as well as on rat brain α3β4 and α7 nicotinic acetylcholine receptors (AChRs) expressed in Xenopus oocytes.As expected, KB-R7943 blocked the Na+-gradient dependent 45Ca2+ uptake into chromaffin cells (IC50 of 5.5 μM); but in addition, the compound also inhibited the 45Ca2+ entry and the increase of cytosolic Ca2+ concentration, [Ca2+]c, stimulated by 5 s pulses of ACh (IC50 of 6.5 and 1.7 μM, respectively).In oocytes expressing α3β4 and α7 nicotinic AChRs, voltage-clamped at −60 mV, inward currents elicited by 1 s pulses of 100 μM ACh (IACh) were blocked by KB-R7943 with an IC50 of 0.4 μM and a Hill coefficient of 0.9.Blockade of α3β4 currents by KB-R7943 was noncompetitive; moreover, the blocker (0.3 μM) became more active as the ACh concentration increased (34 versus 66% blockade at 30 μM and 1 mM ACh, respectively).Inhibition of α3β4 currents by 0.3 μM KB-R7943 was more pronounced at hyperpolarized potentials. If given within the ACh pulse (10 μM), the inhibition amounted to 33, 64 and 80% in oocytes voltage-clamped at −40, −60 and −100 mV, respectively. The onset of blockade was faster and the recovery slower at −100 mV; the reverse was true at −40 mV.In conclusion, KB-R7943 is a potent blocker of nicotinic AChRs; moreover, it displays many features of an open-channel blocker at the rat brain α3β4 AChR. These results should be considered when KB-R7943 is to be used to study Ca2+ homeostasis in cells expressing nicotinic AChRs and the Na+/Ca2+ exchanger. PMID:10952680

  9. 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

  10. Trophic factor-induced excitatory synaptogenesis involves postsynaptic modulation of nicotinic acetylcholine receptors.

    Science.gov (United States)

    Woodin, Melanie A; Munno, David W; Syed, Naweed I

    2002-01-15

    Neurotrophic factors have well established roles in neuronal development, although their precise involvement in synapse formation and plasticity is yet to be fully determined. Using soma-soma synapses between identified Lymnaea neurons, we have shown recently that trophic factors are required for excitatory but not inhibitory synapse formation. However, neither the precise site (presynaptic versus postsynaptic cell) nor the underlying mechanisms have yet been defined. In the present study, synapse formation between the presynaptic cell visceral dorsal 4 (VD4) and its postsynaptic partner right pedal dorsal 1 (RPeD1) was examined to define the cellular mechanisms mediating trophic factor-induced excitatory synaptogenesis in cell culture. When paired in a soma-soma configuration in the presence of defined media (DM, nonproteinacious), mutually inhibitory synapses were appropriately reconstructed between VD4 and RPeD1. However, when cells were paired in the presence of increasing concentrations of Lymnaea brain-conditioned medium (CM), a biphasic synapse (initial excitatory synaptic component followed by inhibition) developed. The CM-induced excitatory synapse formation required trophic factor-mediated activation of receptor tyrosine kinases in the postsynaptic cell, RPeD1, and a concomitant modulation of existing postsynaptic nicotinic acetylcholine receptors (nAChRs). Specifically, when RPeD1 was isolated in DM, exogenously applied ACh induced a hyperpolarizing response that was sensitive to the AChR antagonist methyllycaconitine (MLA). In contrast, a single RPeD1 isolated in CM exhibited a biphasic response to exogenously applied ACh. The initial depolarizing phase of the biphasic response was sensitive to both mecamylamine and hexamethonium chloride, whereas the hyperpolarizing phase was blocked by MLA. In soma-soma-paired neurons, the VD4-induced synaptic responses in RPeD1 were sensitive to the cholinergic antagonists in a concentration range similar to that

  11. Peptides from puff adder Bitis arietans venom, novel inhibitors of nicotinic acetylcholine receptors.

    Science.gov (United States)

    Vulfius, Catherine A; Spirova, Ekaterina N; Serebryakova, Marina V; Shelukhina, Irina V; Kudryavtsev, Denis S; Kryukova, Elena V; Starkov, Vladislav G; Kopylova, Nina V; Zhmak, Maxim N; Ivanov, Igor A; Kudryashova, Ksenia S; Andreeva, Tatyana V; Tsetlin, Victor I; Utkin, Yuri N

    2016-10-01

    Phospholipase A2 (named bitanarin) possessing capability to block nicotinic acetylcholine receptors (nAChRs) was isolated earlier (Vulfius et al., 2011) from puff adder Bitis arietans venom. Further studies indicated that low molecular weight fractions of puff adder venom inhibit nAChRs as well. In this paper, we report on isolation from this venom and characterization of three novel peptides called baptides 1, 2 and 3 that reversibly block nAChRs. To isolate the peptides, the venom of B. arietans was fractionated by gel-filtration and reversed phase chromatography. The amino acid sequences of peptides were established by de novo sequencing using MALDI mass spectrometry. Baptide 1 comprised 7, baptides 2 and 3-10 amino acid residues, the latter being acetylated at the N-terminus. This is the first indication for the presence of such post-translational modification in snake venom proteins. None of the peptides contain cysteine residues. For biological activity studies the peptides were prepared by solid phase peptide synthesis. Baptide 3 and 2 blocked acetylcholine-elicited currents in isolated Lymnaea stagnalis neurons with IC50 of about 50 μM and 250 μM, respectively. In addition baptide 2 blocked acetylcholine-induced currents in muscle nAChR heterologously expressed in Xenopus oocytes with IC50 of about 3 μM. The peptides did not compete with radioactive α-bungarotoxin for binding to Torpedo and α7 nAChRs at concentration up to 200 μM that suggests non-competitive mode of inhibition. Calcium imaging studies on α7 and muscle nAChRs heterologously expressed in mouse neuroblastoma Neuro2a cells showed that on α7 receptor baptide 2 inhibited acetylcholine-induced increasing intracellular calcium concentration with IC50 of 20.6 ± 3.93 μM. On both α7 and muscle nAChRs the suppression of maximal response to acetylcholine by about 50% was observed at baptide 2 concentration of 25 μM, the value being close to IC50 on α7 nAChR. These data are in

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

    Directory of Open Access Journals (Sweden)

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

    Directory of Open Access Journals (Sweden)

    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.

  14. Nicotinic receptor alpha7 expression identifies a novel hematopoietic progenitor lineage.

    Directory of Open Access Journals (Sweden)

    Lorise C Gahring

    Full Text Available How inflammatory responses are mechanistically modulated by nicotinic acetylcholine receptors (nAChR, especially by receptors composed of alpha7 (α7 subunits, is poorly defined. This includes a precise definition of cells that express α7 and how these impact on innate inflammatory responses. To this aim we used mice generated through homologous recombination that express an Ires-Cre-recombinase bi-cistronic extension of the endogenous α7 gene that when crossed with a reporter mouse expressing Rosa26-LoxP (yellow fluorescent protein (YFP marks in the offspring those cells of the α7 cell lineage (α7(lin+. In the adult, on average 20-25 percent of the total CD45(+ myeloid and lymphoid cells of the bone marrow (BM, blood, spleen, lymph nodes, and Peyers patches are α7(lin+, although variability between litter mates in this value is observed. This hematopoietic α7(lin+ subpopulation is also found in Sca1(+cKit(+ BM cells suggesting the α7 lineage is established early during hematopoiesis and the ratio remains stable in the individual thereafter as measured for at least 18 months. Both α7(lin+ and α7(lin- BM cells can reconstitute the immune system of naïve irradiated recipient mice and the α7(lin+:α7(lin- beginning ratio is stable in the recipient after reconstitution. Functionally the α7(lin+:α7(lin- lineages differ in response to LPS challenge. Most notable is the response to LPS as demonstrated by an enhanced production of IL-12/23(p40 by the α7(lin+ cells. These studies demonstrate that α7(lin+ identifies a novel subpopulation of bone marrow cells that include hematopoietic progenitor cells that can re-populate an animal's inflammatory/immune system. These findings suggest that α7 exhibits a pleiotropic role in the hematopoietic system that includes both the direct modulation of pro-inflammatory cell composition and later in the adult the role of modulating pro-inflammatory responses that would impact upon an individual

  15. 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.

  16. [Bacterial expression of water-soluble domain of Lynx1, endogenic neuromodulator of human nicotinic acetylcholine receptors].

    Science.gov (United States)

    Shulepko, M A; Liukmanova, E N; Kasheverov, I E; Dolgikh, D A; Tsetlin, V I; Kirpichnikov, M P

    2011-01-01

    Lynx1 expresses in the central nervous system and plays important role in a regulation of nicotinic acetylcholine receptors. Successful milligram-quantitive expression of ws-Lynx1 was achieved only in the case of its production in the form of cytoplasm inclusion bodies. Different conditions of ws-Lynx1 refolding for yield optimization were performed. The obtained recombinant protein was characterized by means of mass spectrometry and CD spectroscopy. The binding experiments on the nAChRs from Torpedo californica membranes revealed that ws-Lynxl is biologically active and blocks muscle nAChR with IC50-20-30 microM.

  17. 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

  18. Stimulation of α7 nicotinic acetylcholine receptor regulates glutamate transporter GLAST via basic fibroblast growth factor production in cultured cortical microglia.

    Science.gov (United States)

    Morioka, Norimitsu; Harano, Sakura; Tokuhara, Masato; Idenoshita, Yuko; Zhang, Fang Fang; Hisaoka-Nakashima, Kazue; Nakata, Yoshihiro

    2015-11-01

    The α7 nicotinic acetylcholine (nACh) receptor expressed in microglia has a crucial role in neuroprotection. Simulation of α7 nACh receptor leads to increased expression of glutamate/aspartate transporter (GLAST), which in turn decreases synaptic glutamate levels. However, the upregulation of GLAST in cultured rat cortical microglia appears long after (over 18 h) stimulation of the α7 nACh receptor with nicotine. Thus, the current study elucidated the pathway responsible for the induction of GLAST expression in cultured cortical microglia. Nicotine-induced GLAST mRNA expression was significantly inhibited by cycloheximide pretreatment, indicating that a protein intermediary, such as a growth factor, is required for GLAST expression. The expression of fibroblast growth factor-2 (FGF-2) mRNA in cortical microglia was significantly increased 6 and 12h after treatment with nicotine, and this increase was potently inhibited by pretreatment with methyllycaconitine, a selective α7 nACh receptor antagonist. The treatment with nicotine also significantly increased FGF-2 protein expression. Furthermore, treatment with recombinant FGF-2 increased GLAST mRNA, protein expression and (14)C-glutamate uptake, a functional measurement of GLAST activity. Conversely, pretreatment with PD173074, an inhibitor of FGF receptor (FGFR) tyrosine kinase, significantly prevented the nicotine-induced expression of GLAST mRNA, its protein and (14)C-glutamate uptake. Reverse transcription polymerase chain reaction confirmed FGFR1 mRNA expression was confined to cultured cortical microglia. Together, the current findings demonstrate that the neuroprotective effect of activation of microglial α7 nACh receptors could be due to the expression of FGF-2, which in turn increases GLAST expression, thereby clearing glutamate from synapse and decreasing glutamate neurotransmission.

  19. 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

    The neuronal alpha 7 nicotinic acetylcholine receptor is a homo-pentameric ligand-gated ion channel that is a promising drug target for cognitive deficits in Alzheimer's disease and schizophrenia. We have previously described 11C-NS14492 as a suitable agonist radioligand for in vivo positron....../mg protein. This binding assay further revealed the Ki rank order for a number of alpha 7 nicotinic receptor agonists, and positive allosteric modulators (PAMs). Further, we saw increased binding of 3H-NS14492 to pig frontal cortex membranes when co-incubated with PNU-120596, a type II PAM. Taken together...

  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 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)nAChR bind......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...

  1. The alpha7 nicotinic acetylcholine receptor-selective antagonist, methyllycaconitine, partially protects against beta-amyloid1-42 toxicity in primary neuron-enriched cultures.

    Science.gov (United States)

    Martin, Shelley E; de Fiebre, Nancy Ellen C; de Fiebre, Christopher M

    2004-10-01

    Studies have suggested that the neuroprotective actions of alpha7 nicotinic agonists arise from activation of receptors and not from the extensive desensitization which rapidly follows activation. Here, we report that the alpha7-selective nicotinic antagonist, methyllycaconitine (MLA), protects against beta-amyloid-induced neurotoxicity; whereas the alpha4beta2-selective antagonist, dihydro-beta-erythroidine, does not. These findings suggest that neuroprotective actions of alpha7-acting agents arise from receptor inhibition/desensitization and that alpha7 antagonists may be useful neuroprotective agents.

  2. Rescue of amyloid-Beta-induced inhibition of nicotinic acetylcholine receptors by a peptide homologous to the nicotine binding domain of the alpha 7 subtype.

    Directory of Open Access Journals (Sweden)

    Arthur A Nery

    Full Text Available Alzheimer's disease (AD is characterized by brain accumulation of the neurotoxic amyloid-β peptide (Aβ and by loss of cholinergic neurons and nicotinic acetylcholine receptors (nAChRs. Recent evidence indicates that memory loss and cognitive decline in AD correlate better with the amount of soluble Aβ than with the extent of amyloid plaque deposits in affected brains. Inhibition of nAChRs by soluble Aβ40 is suggested to contribute to early cholinergic dysfunction in AD. Using phage display screening, we have previously identified a heptapeptide, termed IQ, homologous to most nAChR subtypes, binding with nanomolar affinity to soluble Aβ40 and blocking Aβ-induced inhibition of carbamylcholine-induced currents in PC12 cells expressing α7 nAChRs. Using alanine scanning mutagenesis and whole-cell current recording, we have now defined the amino acids in IQ essential for reversal of Aβ40 inhibition of carbamylcholine-induced responses in PC12 cells, mediated by α7 subtypes and other endogenously expressed nAChRs. We further investigated the effects of soluble Aβ, IQ and analogues of IQ on α3β4 nAChRs recombinantly expressed in HEK293 cells. Results show that nanomolar concentrations of soluble Aβ40 potently inhibit the function of α3β4 nAChRs, and that subsequent addition of IQ or its analogues does not reverse this effect. However, co-application of IQ makes the inhibition of α3β4 nAChRs by Aβ40 reversible. These findings indicate that Aβ40 inhibits different subtypes of nAChRs by interacting with specific receptor domains homologous to the IQ peptide, suggesting that IQ may be a lead for novel drugs to block the inhibition of cholinergic function in AD.

  3. Dorsal raphe nucleus acetylcholine-mediated neurotransmission modulates post-ictal antinociception: The role of muscarinic and nicotinic cholinergic receptors.

    Science.gov (United States)

    de Oliveira, Rithiele Cristina; de Oliveira, Ricardo; Biagioni, Audrey Francisco; Falconi-Sobrinho, Luiz Luciano; Coimbra, Norberto Cysne

    2016-01-15

    The dorsal raphe nucleus (DRN) is a key structure of the endogenous pain inhibitory system. Although the DRN is rich in serotoninergic neurons, cholinergic neurons are also found in that nucleus. Both ictal and inter-ictal states are followed by post-ictal analgesia. The present study investigated the role of cholinergic mechanisms in postictal antinociceptive processes using microinjections of atropine and mecamylamine, muscarinic and nicotinic cholinergic receptor antagonists, respectively, in the DRN of rats. Intraperitoneal injection of pentylenetetrazole (PTZ) (at 64mg/kg) caused tonic and tonic-clonic seizures. The convulsive motor reactions were followed by an increase in pain thresholds, a phenomenon known as post-ictal analgesia. Pre-treatment of the DRN with atropine or mecamylamine at 1µg, 3µg and 5µg/0.2µL decreased the post-ictal antinociceptive phenomenon. The present results showed that the post-ictal analgesia was mediated by muscarinic and nicotinic cholinergic receptors in the DRN, a structure crucially involved in the neural network that organises post-ictal hypoalgesia.

  4. Dementia praecox redux: a systematic review of the nicotinic receptor as a target for cognitive symptoms of schizophrenia.

    Science.gov (United States)

    Rowe, Arann R; Mercer, Louise; Casetti, Valentina; Sendt, Kyra-Verena; Giaroli, Giovanni; Shergill, Sukhwinder S; Tracy, Derek K

    2015-02-01

    Most individuals with schizophrenia suffer some cognitive dysfunction: such deficits are predictive of longer-term functioning; and current dopamine-blocking antipsychotics have made little impact on this domain. There is a pressing need to develop novel pharmacological agents to tackle this insidious but most disabling of problems. The acetylcholinergic system is involved in cognitive and attentional processing, and its metabotropic and nicotinic receptors are widespread throughout the brain. Deficits in acetylcholinergic functioning occur in schizophrenia, and high rates of tobacco smoking have been posited to represent a form of self-medication. The nicotinic acetylcholine receptor (nAChR) has emerged as a putative target to improve cognitive deficits in schizophrenia, and this study systematically reviewed the emerging data. Nineteen studies were identified, covering three compound classes: agonists at the α7 and α 4β2 nAChRs, and positive allosteric modulators. Overall data are underwhelming: some studies showed significant improvements in cognition but as many studies had negative findings. It remains unclear if this represents drug limitations or nascent study methodology problems. The literature is particularly hindered by variability in inclusion of smokers, generally small sample sizes, and a lack of consensus on cognitive test batteries. Future work should evaluate longer-term outcomes, and, particularly, the effects of concomitant cognitive training. © The Author(s) 2015.

  5. Selective potentiation of (α4)3(β2)2 nicotinic acetylcholine receptors augments amplitudes of prefrontal acetylcholine- and nicotine-evoked glutamatergic transients in rats.

    Science.gov (United States)

    Grupe, Morten; Paolone, Giovanna; Jensen, Anders A; Sandager-Nielsen, Karin; Sarter, Martin; Grunnet, Morten

    2013-11-15

    Prefrontal glutamate release evoked through activation of α4β2* nicotinic acetylcholine receptors (nAChRs) situated on thalamic glutamatergic afferents mediates cue detection processes and thus contributes to attentional performance. However, little is known about the respective contributions of the high sensitivity and low sensitivity (LS) stoichiometries of the α4β2 nAChR, (α4)2(β2)3 and (α4)3(β2)2, to these processes. In the present study we employed glutamate-sensitive microelectrodes and the (α4)3(β2)2-selective positive allosteric modulator (PAM) NS9283 to investigate the importance of the LS α4β2 nAChR for glutamate release in the rat medial prefrontal cortex (mPFC). Firstly, the signaling evoked by physiologically relevant ACh concentrations through the (α4)3(β2)2 nAChR in HEK293 cells was potentiated by NS9283, consistent with the classification of NS9283 as a PAM. In urethane-anesthetized rats, intra-prefrontal pressure ejections of NS9283 evoked glutamatergic transients. Importantly, this glutamate release was attenuated by removal of cholinergic projections to the recording area. This finding indicates that the effects of NS9283 depend on endogenous ACh, again consistent with effects of a PAM. We then conducted microdialysis to demonstrate the presence of extracellular ACh in urethane-anesthetized control rats. While detectable, those levels were significantly lower than in awake rats. Finally, the amplitudes of glutamatergic transients evoked by local pressure ejections of a low concentration of nicotine were significantly augmented following systemic administration of NS9283 (3.0mg/kg). In conclusion, our results indicate that a LS α4β2 nAChR PAM such as NS9283 may enhance the cholinergic modulation of glutamatergic neurotransmission in the cortex, thereby perhaps alleviating the attentional impairments common to a range of brain disorders. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Morphine-induced anxiolytic-like effect in morphine-sensitized mice: involvement of ventral hippocampal nicotinic acetylcholine receptors.

    Science.gov (United States)

    Rezayof, Ameneh; Assadpour, Sara; Alijanpour, Sakineh

    2013-01-01

    In the present study, the effects of repeated intra-ventral hippocampal (intra-VH) microinjections of nicotinic acetylcholine receptor agonist or antagonist on morphine-induced anxiolytic-like behavior were investigated in morphine-sensitized mice using elevated plus-maze. Intraperitoneal (i.p.) administration of different doses of morphine (5, 7.5 and 10mg/kg) increased the percentage of open arm time (%OAT), open arm entries (%OAE), but not locomotor activity, indicating an anxiolytic-like response to morphine. The maximum response was obtained by 7.5mg/kg of the opioid. The anxiety-like behavior which was induced by a lower dose of morphine (5mg/kg) was significantly increased in mice that had previously received once daily injections of morphine (10 and 20mg/kg, i.p.) for 3 days. It should be considered that this treatment also increased locomotor activity in morphine-sensitized mice. Furthermore, the response to an ineffective dose of morphine (5mg/kg, i.p.) in the EPM was significantly increased in the animals that had previously received nicotine for 3 days (0.1, 0.3, 0.5 and 0.7 μg/mouse; intra-VH), 5 min prior to the injections of morphine (5mg/kg/day × 3 days; i.p.). On the other hand, the increase of morphine-induced anxiolytic-like effect in animals that had previously received the 3-day morphine (20mg/kg) was dose dependently suppressed by once daily injections of mecamylamine (0.5, 1 and 2 μg/mouse/day × 3 days; intra-VH). It is important to note that repeated intra-VH administrations of the same doses of nicotine or mecamylamine alone caused no significant change in morphine (5mg/kg)-induced anxiety-like parameters in the EPM. In conclusion, it seems that morphine sensitization affects the anxiety-like behavior in the EPM and the cholinergic system in the ventral hippocampus, via nicotinic receptors, may play an important role in this effect.

  7. Synergistic inhibitory effect of nicotine plus oral contraceptive on mitochondrial complex-IV is mediated by estrogen receptor-β in female rats.

    Science.gov (United States)

    Raval, Ami P; Dave, Kunjan R; Saul, Isabel; Gonzalez, Gabriel J; Diaz, Francisca

    2012-04-01

    Chronic nicotine and oral contraceptive (NOC) exposure caused significant loss of hippocampal membrane-bound estrogen receptor-beta (ER-β) in female rats compared with exposure to nicotine alone. Mitochondrial ER-β regulates estrogen-mediated mitochondrial structure and function; therefore, investigating the impact of NOC on mitochondrial ER-β and its function could help delineate the harmful synergism between nicotine and OC. In this study, we tested the hypothesis that NOC-induced loss of mitochondrial ER-β alters the oxidative phosphorylation system protein levels and mitochondrial respiratory function. This hypothesis was tested in hippocampal mitochondria isolated from female rats exposed to saline, nicotine, OC or NOC for 16 days. NOC decreased the mitochondrial ER-β protein levels and reduced oxygen consumption and complex IV (CIV) activity by 34% and 26% compared with saline- or nicotine-administered groups, respectively. We also observed significantly low protein levels of all mitochondrial-encoded CIV subunits after NOC as compared with the nicotine or saline groups. Similarly, the silencing of ER-β reduced the phosphorylation of cyclic-AMP response element binding protein, and also reduced levels of CIV mitochondrial-encoded subunits after estrogen stimulation. Overall, these results suggest that mitochondrial ER-β loss is responsible for mitochondrial malfunction after NOC.

  8. Characterization of the retina in the alpha7 nicotinic acetylcholine receptor knockout mouse

    Science.gov (United States)

    Smith, Marci L.

    Acetylcholine receptors (AChRs) are involved in visual processing and are expressed by inner retinal neurons in all species studied to date (Keyser et al., 2000; Dmitrieva et al., 2007; Liu et al., 2009), but their distribution in the mouse retina remains unknown. Reductions in alpha7 nicotinic AChRs (nAChRs) are thought to contribute to memory and visual deficits observed in Alzheimer's and schizophrenia (Coyle et al., 1983; Nordberg et al., 1999; Leonard et al., 2006). However, the alpha7 nAChR knockout (KO) mouse has a mild phenotype (Paylor et al., 1998; Fernandes et al., 2006; Young et al., 2007; Origlia et al., 2012). The purpose of this study was to determine the expression of AChRs in wildtype (WT) mouse retina and to assess whether up-regulation of other AChRs in the alpha7 nAChR KO retina may explain the minimal deficits described in the KO mouse. Reverse-transcriptase PCR (RT-PCR) showed that mRNA transcripts for alpha2-7, alpha 9, alpha10, beta2-4 nAChR subunits and m1-m5 muscarinic AChR (mAChR) subtypes were present in WT murine retina. Western blot analysis confirmed the presence of alpha3-5, alpha9, and m1-m5 AChR proteins and immunohistochemical analysis demonstrated nAChR and mAChR proteins expressed by subsets of bipolar, amacrine and ganglion cells. This is the first reported expression of alpha9 and alpha10 nAChR transcripts and alpha9 nAChR proteins in the retina of any species. Quantitative RT-PCR (qPCR) showed changes in AChR transcript expression in the alpha7 nAChR KO mouse retina relative to WT. Within whole retina alpha2, alpha9, alpha10, beta4, m1 and m4 AChR transcripts were up-regulated, while alpha5 nAChR transcripts were down-regulated. However, cell populations showed subtle differences; m4 mAChR transcripts were up-regulated in the ganglion cell layer and outer portion of the inner nuclear layer (oINL),while beta4 nAChR transcript up-regulation was limited to the oINL. Surprisingly, alpha2, alpha9, beta4, m2 and m4 transcripts were

  9. Maximizing the effect of an α7 nicotinic receptor PAM in a mouse model of schizophrenia-like sensory inhibition deficits.

    Science.gov (United States)

    Stevens, Karen E; Zheng, Lijun; Floyd, Kirsten L; Stitzel, Jerry A

    2015-06-22

    Positive allosteric modulators (PAMs) for the α7 nicotinic receptor hold promise for the treatment of sensory inhibition deficits observed in schizophrenia patients. Studies of these compounds in the DBA/2 mouse, which models the schizophrenia-related deficit in sensory inhibition, have shown PAMs to be effective in improving the deficit. However, the first published clinical trial of a PAM for both sensory inhibition deficits and related cognitive difficulties failed, casting a shadow on this therapeutic approach. The present study used both DBA/2 mice, and C3H Chrna7 heterozygote mice to assess the ability of the α7 PAM, PNU-120596, to improve sensory inhibition. Both of these strains of mice have reduced hippocampal α7 nicotinic receptor numbers and deficient sensory inhibition similar to schizophrenia patients. Low doses of PNU-120596 (1 or 3.33mg/kg) were effective in the DBA/2 mouse but not the C3H Chrna7 heterozygote mouse. Moderate doses of the selective α7 nicotinic receptor agonist, choline chloride (10 or 33mg/kg), were also ineffective in improving sensory inhibition in the C3H Chrna7 heterozygote mouse. However, combining the lowest doses of both PNU-120596 and choline chloride in this mouse model did improve sensory inhibition. We propose here that the difference in efficacy of PNU-120596 between the 2 mouse strains is driven by differences in hippocampal α7 nicotinic receptor numbers, such that C3H Chrna7 heterozygote mice require additional direct stimulation of the α7 receptors. These data may have implications for further clinical testing of putative α7 nicotinic receptor PAMs.

  10. 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

  11. Nicotinic Acetylcholine Receptors in the Pathophysiology of Alzheimer's Disease: The Role of Protein-Protein Interactions in Current and Future Treatment

    DEFF Research Database (Denmark)

    Lindskov, Morten Skøtt Thomsen; 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...

  12. Dianicline, a novel α4β2 nicotinic acetylcholine receptor partial agonist, for smoking cessation: a randomized placebo-controlled clinical trial

    DEFF Research Database (Denmark)

    Tonstad, Serena; Holme, Ingar; Tønnesen, Philip

    2011-01-01

    Dianicline is a α4β2 nicotinic acetylcholine receptor partial agonist, a class of drugs that includes varenicline and cytisine. Varenicline is efficacious for smoking cessation, while cytisine has not been studied systematically. The efficacy of dianicline has not been previously tested...

  13. Solid-phase synthesis and pharmacological evaluation of analogues of PhTX-12-A potent and selective nicotinic acetylcholine receptor antagonist

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Mellor, Ian R; Andersen, Kim;

    2002-01-01

    Philanthotoxin-12 (PhTX-12) is a novel potent and selective, noncompetitive antagonist of nicotinic acetylcholine receptors (nAChRs). Homologues of PhTX-12 with 7-11 methylene groups between the primary amino group and the aromatic head-group were synthesized using solid-phase methodology. In vitro...

  14. 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

    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 level...

  15. Positive allosteric modulators of the α7 nicotinic acetylcholine receptor potentiate glutamate release in the prefrontal cortex of freely-moving rats

    DEFF Research Database (Denmark)

    Bortz, D M; Upton, B A; Mikkelsen, J D

    2016-01-01

    Positive allosteric modulators (PAMs) of α7 nicotinic acetylcholine receptors (α7nAChRs) exhibit pro-cognitive effects in animal models of schizophrenia and are targets for the discovery of cognition-enhancing drugs. However, little is known about their in vivo mechanism of action because such st...

  16. Pharmacological characterization of dopamine, norepinephrine and serotonin release in the rat prefrontal cortex by neuronal nicotinic acetylcholine receptor agonists.

    Science.gov (United States)

    Rao, Tadimeti S; Correa, Lucia D; Adams, Pamala; Santori, Emily M; Sacaan, Aida I

    2003-11-14

    Neuronal nicotinic acetylcholine receptors (nAChRs) modulate synaptic transmission by regulating neurotransmitter release, an action that involves multiple nAChRs. The effects of four nAChR agonists, nicotine (NIC), 1,1-dimethyl-4-phenylpiperzinium iodide (DMPP), cytisine (CYT) and epibatidine (EPI) were investigated on [3H]-norepinephrine (NE), [3H]-dopamine (DA) and [3H]-serotonin (5-HT) release from rat prefrontal cortical (PFC) slices. All four agonists evoked [3H]-DA release to a similar magnitude but with a differing rank order of potency of EPI>DMPP approximately NIC approximately CYT. Similarly, all four agonists also increased [3H]-NE release, but with a differing rank order of potency of EPI>CYT approximately DMPP>NIC. NIC-induced [3H]-NE and [3H]-DA release responses were both calcium-dependent and attenuated by the sodium channel antagonist, tetrodotoxin (TTX) and by the nAChR antagonists mecamylamine (MEC) and dihydro-beta-erythroidine (DHbetaE), but not by D-tubocurare (D-TC). The modulation of [3H]-5-HT release by nAChR agonists was distinct from that seen for catecholamines. DMPP produced robust increases with minimal release observed with other agonists. DMPP-induced [3H]-5-HT release was neither sensitive to known nAChR antagonists nor dependent on external calcium. The differences between nicotinic agonist induced catecholamine and serotonin release suggest involvement of distinct nAChRs.

  17. A point mutation in the hair cell nicotinic cholinergic receptor prolongs cochlear inhibition and enhances noise protection.

    Directory of Open Access Journals (Sweden)

    Julian Taranda

    2009-01-01

    Full Text Available The transduction of sound in the auditory periphery, the cochlea, is inhibited by efferent cholinergic neurons projecting from the brainstem and synapsing directly on mechanosensory hair cells. One fundamental question in auditory neuroscience is what role(s this feedback plays in our ability to hear. In the present study, we have engineered a genetically modified mouse model in which the magnitude and duration of efferent cholinergic effects are increased, and we assess the consequences of this manipulation on cochlear function. We generated the Chrna9L9'T line of knockin mice with a threonine for leucine change (L9'T at position 9' of the second transmembrane domain of the alpha9 nicotinic cholinergic subunit, rendering alpha9-containing receptors that were hypersensitive to acetylcholine and had slower desensitization kinetics. The Chrna9L9'T allele produced a 3-fold prolongation of efferent synaptic currents in vitro. In vivo, Chrna9L9'T mice had baseline elevation of cochlear thresholds and efferent-mediated inhibition of cochlear responses was dramatically enhanced and lengthened: both effects were reversed by strychnine blockade of the alpha9alpha10 hair cell nicotinic receptor. Importantly, relative to their wild-type littermates, Chrna9(L9'T/L9'T mice showed less permanent hearing loss following exposure to intense noise. Thus, a point mutation designed to alter alpha9alpha10 receptor gating has provided an animal model in which not only is efferent inhibition more powerful, but also one in which sound-induced hearing loss can be restrained, indicating the ability of efferent feedback to ameliorate sound trauma.

  18. Influence of naloxone on catecholamine release evoked by nicotinic receptor stimulation in the isolated rat adrenal gland.

    Science.gov (United States)

    Kim, Ok-Min; Lim, Geon-Han; Lim, Dong-Yoon

    2005-06-01

    The present study was designed to investigate the effect of naloxone, a well known opioid antagonist, on the secretion of catecholamines (CA) evoked by cholinergic stimulation and membrane-depolarization in the isolated perfused rat adrenal glands, and to establish its mechanism of action. Naloxone (10(-6) approximately 10(-5) M), perfused into an adrenal vein for 60 min, produced dose- and time-dependent inhibition of CA secretory responses evoked by ACh (5.32 x 10(-3) M), high K+ (5.6 x 10(-2) M), DMPP (10(-4) M) and McN-A-343 (10(-4) M). Naloxone itself also failed to affect the basal CA output. In adrenal glands loaded with naloxone (3 x 10(-6) M), the CA secretory responses evoked by Bay-K-8644, an activator of L-type Ca2+ channels, and cyclopiazonic acid, an inhibitor of cytoplasmic Ca(2+)-ATPase, were also inhibited. In the presence of met-enkephalin (5 x 10(-6) M), a well known opioid agonist, the CA secretory responses evoked by ACh, high K+, DMPP, McN-A-343, Bay-K-8644 and cyclopiazonic acid were also significantly inhibited. Taken together, these results suggest that naloxone greatly inhibits the CA secretion evoked by stimulation of cholinergic (both nicotinic and muscarinic) receptors as well as that by membrane depolarization. It seems that these inhibitory effects of naloxone does not involve opioid receptors, but might be mediated by blocking both the calcium influx into the rat adrenal medullary chromaffin cells and the uptake of Ca2+ into the cytoplasmic calcium store, which are at least partly relevant to the direct interaction with the nicotinic receptor itself.

  19. Competition, Selectivity and Efficacy of Analogs of A-84543 for Nicotinic Acetylcholine Receptors with Repositioning of Pyridine Nitrogen

    Science.gov (United States)

    Ogunjirin, Adebowale E.; Fortunak, Joseph M.; Brown, LaVerne L.; Xiao, Yingxian; Dávila-García, Martha I.

    2015-01-01

    Nicotinic acetylcholine receptors (nAChRs) play a crucial role in a number of clinically relevant mental and neurological pathways, as well as autonomic and immune functions. The development of subtype-selective ligands for nAChRs therefore is potentially useful for targeted therapeutic management of conditions where nAChRs are involved. We tested if selectivity for a particular nAChR subtype can be achieved through small structural modifications of a lead compound containing the nicotinic pharmacophore by changing the distance between the electronegative elements. For this purpose, analogs of A-84543 were designed, synthesized and characterized as potentially new nAChR subtype-selective ligands. Compounds were tested for their binding properties in rat cerebral cortical tissue homogenates, and subtype-selectivity was determined using stably transfected HEK cells expressing different nAChR subtypes. All compounds synthesized were found to competitively displace [3H]-epibatidine ([3H]EB) from the nAChR binding site. Of all the analogues, H-11MNH showed highest affinity for nAChRs compared to a ~ 5 to10-fold lower affinity of A-84543. All other compounds had affinities > 10,000 nM. Both A-84543 and H-11MNH have highest affinity for α2β2 and α4β2 nAChRs and show moderate affinity for β4- and α7-containing receptors. H-11MNH was found to be a full agonist with high potency at α3β4, while A-84543 is a partial agonist with low potency. Based on their unique pharmacological binding properties we suggest that A-84543 and its desmethylpyrrolidine analog can be useful as pharmacological ligands for studying nAChRs if selective pharmacological and/or genetic tools are used to mask the function of other receptors subtypes. PMID:26508288

  20. Pharmacokinetics of cytisine, an α4 β2 nicotinic receptor partial agonist, in healthy smokers following a single dose.

    Science.gov (United States)

    Jeong, Soo Hee; Newcombe, David; Sheridan, Janie; Tingle, Malcolm

    2015-06-01

    Cytisine, an α4 β2 nicotinic receptor partial agonist, is a plant alkaloid that is commercially extracted for use as a smoking cessation medication. Despite its long history of use, there is very little understanding of the pharmacokinetics of cytisine. To date, no previous studies have reported cytisine concentrations in humans following its use as a smoking cessation agent. A high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed and validated for analysis of Tabex® and nicotine-free oral strips, two commercial products containing cytisine. A sensitive liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the quantification of cytisine in human plasma and for the detection of cytisine in urine. Single-dose pharmacokinetics of cytisine was studied in healthy smokers. Subjects received a single 3 mg oral dose administration of cytisine. Cytisine was detected in all plasma samples collected after administration, including 15 min post-dose and at 24 h. Cytisine was renally excreted and detected as an unchanged drug. No metabolites were detected in plasma or urine collected in the study. No adverse reactions were reported.

  1. Protracted treatment with MDMA induces heteromeric nicotinic receptor up-regulation in the rat brain: an autoradiography study.

    Science.gov (United States)

    Ciudad-Roberts, Andrés; Camarasa, Jorge; Pubill, David; Escubedo, Elena

    2014-08-04

    Previous studies indicate that 3,4-methylenedioxy-methamphetamine (MDMA, ecstasy) can induce a heteromeric nicotinic acetylcholine receptor (nAChR, mainly of α4β2 subtype) up-regulation. In this study we treated male Sprague-Dawley rats twice-daily for 10 days with either saline or MDMA (7 mg/kg) and sacrificed them the day after to perform [(125)I]Epibatidine binding autoradiograms on serial coronal slices. MDMA induced significant increases in nAChR density in the substantia nigra, ventral tegmental area, nucleus accumbens, olfactory tubercle, anterior caudate-putamen, somatosensory, motor, auditory and retrosplenial cortex, laterodorsal thalamus nuclei, amygdala, postsubiculum and pontine nuclei. These increases ranged from 3% (retrosplenial cortex) to 30 and 34% (amygdala and substantia nigra). No increased α4 subunit immunoreactivity was found in up-regulated areas compared with saline-treated rats, suggesting a post-translational mechanism as occurs with nicotine. The heteromeric nAChR up-regulation in certain areas could account, at least in part, for the reinforcing, sensitizing and psychiatric disorders observed after long-term consumption of MDMA.

  2. Role of the extracellular transmembrane domain interface in gating and pharmacology of a heteromeric neuronal nicotinic receptor.

    Science.gov (United States)

    Aldea, Marcos; Castillo, Mar; Mulet, José; Sala, Salvador; Criado, Manuel; Sala, Francisco

    2010-05-01

    Nicotinic acetylcholine receptors (nAChRs) transmit the agonist signal to the channel gate through a number of extracellular domains. We have previously shown that particular details of the process of coupling binding to gating could be quantitative and qualitatively different in muscle and neuronal type nAChRs. We have extended previous studies on homomeric alpha7 nAChRs to heteromeric alpha3beta4 nAChRs, by mutating residues located at loops 2 and 7, and M2-M3 linker of both alpha3 and beta4 subunits which, in order to monitor surface expression, were modified to bind alpha-bungarotoxin, and expressed in Xenopus oocytes. We show that, in general, mutations in these domains of both alpha3 and beta4 subunits affect the gating function, although the effects are slightly larger if they are inserted in the alpha3 subunit. However, the involvement of a previously reported intrasubunit interaction in coupling (Gln48-Ile130) seems to be restricted to the beta4 subunit. We also show that mutations at these domains, particularly loop 2 of the alpha3 subunit, change the pharmacological profile of alpha3beta4 nAChRs, decreasing nicotine's and increasing cytisine's effectiveness relative to acetylcholine. It is concluded that, unlike muscle nAChRs, the non-alpha subunits play a relevant role in the coupling process of neuronal alpha3beta4 nAChRs.

  3. Allosteric interaction of the anticholinergic drug [N-(4-phenyl)-phenacyl-l-hyoscyamine] (Phenthonium) with nicotinic receptors of post-ganglionic sympathetic neurons of the rat vas deferens.

    Science.gov (United States)

    Munhoz, Egberto; De Lima, Thereza C M; Souccar, Caden; Lapa, Antonio J; Lima-Landman, Maria Teresa R

    2009-08-15

    Phenthonium (Phen), a quaternary analog of hyoscyamine, is a blocker of muscarinic activity and an allosteric blocker of alpha(1)2betagammaepsilon nicotinic receptors. Specifically, Phenthonium increases the spontaneous release of acetylcholine at the motor endplate without depolarizing the muscle or inhibiting cholinesterase activity. This paper compares Phenthonium's effects on sympathetic transmission and on ganglionic nicotinic receptor activation. Neurotransmitter release and twitch of the rat vas deferens were induced either by electrical stimulation or by 1,1-dimethyl-4-phenylpiperazine (DMPP) activation of nicotinic receptors. Contractions independent of transmitter release were induced by noradrenaline and adenosine 5'-triphosphate (ATP). Phenthonium inhibited transmitter release and depressed twitch without changing the responsiveness to noradrenaline or ATP. Twitch depression did not occur after K(+)-channel blockade with 4-aminopyridine (4-AP) or charybdotoxin. DMPP had a similar effect, but high concentrations induced contraction of non-stimulated organs. Incubation of Phenthonium inhibited further DMPP twitch depression and non-competitively depressed the contractile responses elicited by DMPP. Furthermore, mecamylamine, but neither methyllycaconitine nor atropine, blocked the contraction elicited by DMPP. Phenthonium and DMPP are K(+)-channel openers that primarily inhibit sympathetic transmission. Contraction induced by DMPP was probably mediated by neuronal nicotinic receptor other than the alpha7 subtype. The blockade of DMPP contractile response was unrelated to Phenthonium's antimuscarinic or K(+)-channel opening activities. Since Phenthonium's quaternary chemical structure limits its membrane diffusion, the non-competitive inhibition of DMPP excitatory responses should be linked to allosteric interaction with neuronal nicotinic receptors that putatively qualify Phenthonium as a novel modulator of cholinergic synapses.

  4. Nicotinic receptor mediates nitric oxide synthase expression in the rat gastric myenteric plexus.

    OpenAIRE

    1998-01-01

    The mechanism that regulates the synthesis of nitric oxide synthase (NOS), a key enzyme responsible for NO production in the myenteric plexus, remains unknown. We investigated the roles of the vagal nerve and nicotinic synapses in the mediation of NOS synthesis in the gastric myenteric plexus in rats. Truncal vagotomy and administration of hexamethonium significantly reduced nonadrenergic, noncholinergic relaxation, the catalytic activity of NOS, the number of NOS-immunoreactive cells, and th...

  5. α4β2 Nicotinic Acetylcholine Receptors: RELATIONSHIPS BETWEEN SUBUNIT STOICHIOMETRY AND FUNCTION AT THE SINGLE CHANNEL LEVEL.

    Science.gov (United States)

    Mazzaferro, Simone; Bermudez, Isabel; Sine, Steven M

    2017-02-17

    Acetylcholine receptors comprising α4 and β2 subunits are the most abundant class of nicotinic acetylcholine receptor in the brain. They contribute to cognition, reward, mood, and nociception and are implicated in a range of neurological disorders. Previous measurements of whole-cell macroscopic currents showed that α4 and β2 subunits assemble in two predominant pentameric stoichiometries, which differ in their sensitivity to agonists, antagonists, and allosteric modulators. Here we compare agonist-elicited single channel currents from receptors assembled with an excess of either the α4 or β2 subunit, forming receptor populations biased toward one or the other stoichiometry, with currents from receptors composed of five concatemeric subunits in which the subunit stoichiometry is predetermined. Our results associate each subunit stoichiometry with a unique single channel conductance, mean open channel lifetime, and sensitivity to the allosteric potentiator 3-[3-(3-pyridinyl)-1,2,4-oxadiazol-5-yl]benzonitrile (NS-9283). Receptors with the composition (α4β2)2α4 exhibit high single channel conductance, brief mean open lifetime, and strong potentiation by NS-9283, whereas receptors with the composition (α4β2)2β2 exhibit low single channel conductance and long mean open lifetime and are not potentiated by NS-9283. Thus single channel current measurements reveal bases for the distinct functional and pharmacological properties endowed by different stoichiometries of α4 and β2 subunits and establish pentameric concatemers as a means to delineate interactions between subunits that confer these properties. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Phosphocholine – an agonist of metabotropic but not of ionotropic functions of α9-containing nicotinic acetylcholine receptors

    Science.gov (United States)

    Richter, K.; Mathes, V.; Fronius, M.; Althaus, M.; Hecker, A.; Krasteva-Christ, G.; Padberg, W.; Hone, A. J.; McIntosh, J. M.; Zakrzewicz, A.; Grau, V.

    2016-01-01

    We demonstrated previously that phosphocholine and phosphocholine-modified macromolecules efficiently inhibit ATP-dependent release of interleukin-1β from human and murine monocytes by a mechanism involving nicotinic acetylcholine receptors (nAChR). Interleukin-1β is a potent pro-inflammatory cytokine of innate immunity that plays pivotal roles in host defence. Control of interleukin-1β release is vital as excessively high systemic levels cause life threatening inflammatory diseases. In spite of its structural similarity to acetylcholine, there are no other reports on interactions of phosphocholine with nAChR. In this study, we demonstrate that phosphocholine inhibits ion-channel function of ATP receptor P2X7 in monocytic cells via nAChR containing α9 and α10 subunits. In stark contrast to choline, phosphocholine does not evoke ion current responses in Xenopus laevis oocytes, which heterologously express functional homomeric nAChR composed of α9 subunits or heteromeric receptors containing α9 and α10 subunits. Preincubation of these oocytes with phosphocholine, however, attenuated choline-induced ion current changes, suggesting that phosphocholine may act as a silent agonist. We conclude that phophocholine activates immuno-modulatory nAChR expressed by monocytes but does not stimulate canonical ionotropic receptor functions. PMID:27349288

  7. Phosphocholine - an agonist of metabotropic but not of ionotropic functions of α9-containing nicotinic acetylcholine receptors.

    Science.gov (United States)

    Richter, K; Mathes, V; Fronius, M; Althaus, M; Hecker, A; Krasteva-Christ, G; Padberg, W; Hone, A J; McIntosh, J M; Zakrzewicz, A; Grau, V

    2016-06-28

    We demonstrated previously that phosphocholine and phosphocholine-modified macromolecules efficiently inhibit ATP-dependent release of interleukin-1β from human and murine monocytes by a mechanism involving nicotinic acetylcholine receptors (nAChR). Interleukin-1β is a potent pro-inflammatory cytokine of innate immunity that plays pivotal roles in host defence. Control of interleukin-1β release is vital as excessively high systemic levels cause life threatening inflammatory diseases. In spite of its structural similarity to acetylcholine, there are no other reports on interactions of phosphocholine with nAChR. In this study, we demonstrate that phosphocholine inhibits ion-channel function of ATP receptor P2X7 in monocytic cells via nAChR containing α9 and α10 subunits. In stark contrast to choline, phosphocholine does not evoke ion current responses in Xenopus laevis oocytes, which heterologously express functional homomeric nAChR composed of α9 subunits or heteromeric receptors containing α9 and α10 subunits. Preincubation of these oocytes with phosphocholine, however, attenuated choline-induced ion current changes, suggesting that phosphocholine may act as a silent agonist. We conclude that phophocholine activates immuno-modulatory nAChR expressed by monocytes but does not stimulate canonical ionotropic receptor functions.

  8. 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.

  9. Water-soluble LYNX1 residues important for interaction with muscle-type and/or neuronal nicotinic receptors.

    Science.gov (United States)

    Lyukmanova, Ekaterina N; Shulepko, Mikhail A; Buldakova, Svetlana L; Kasheverov, Igor E; Shenkarev, Zakhar O; Reshetnikov, Roman V; Filkin, Sergey Y; Kudryavtsev, Denis S; Ojomoko, Lucy O; Kryukova, Elena V; Dolgikh, Dmitry A; Kirpichnikov, Mikhail P; Bregestovski, Piotr D; Tsetlin, Victor I

    2013-05-31

    Human LYNX1, belonging to the Ly6/neurotoxin family of three-finger proteins, is membrane-tethered with a glycosylphosphatidylinositol anchor and modulates the activity of nicotinic acetylcholine receptors (nAChR). Recent preparation of LYNX1 as an individual protein in the form of water-soluble domain lacking glycosylphosphatidylinositol anchor (ws-LYNX1; Lyukmanova, E. N., Shenkarev, Z. O., Shulepko, M. A., Mineev, K. S., D'Hoedt, D., Kasheverov, I. E., Filkin, S. Y., Krivolapova, A. P., Janickova, H., Dolezal, V., Dolgikh, D. A., Arseniev, A. S., Bertrand, D., Tsetlin, V. I., and Kirpichnikov, M. P. (2011) NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1. J. Biol. Chem. 286, 10618-10627) revealed the attachment at the agonist-binding site in the acetylcholine-binding protein (AChBP) and muscle nAChR but outside it, in the neuronal nAChRs. Here, we obtained a series of ws-LYNX1 mutants (T35A, P36A, T37A, R38A, K40A, Y54A, Y57A, K59A) and examined by radioligand analysis or patch clamp technique their interaction with the AChBP, Torpedo californica nAChR and chimeric receptor composed of the α7 nAChR extracellular ligand-binding domain and the transmembrane domain of α1 glycine receptor (α7-GlyR). Against AChBP, there was either no change in activity (T35A, T37A), slight decrease (K40A, K59A), and even enhancement for the rest mutants (most pronounced for P36A and R38A). With both receptors, many mutants lost inhibitory activity, but the increased inhibition was observed for P36A at α7-GlyR. Thus, there are subtype-specific and common ws-LYNX1 residues recognizing distinct targets. Because ws-LYNX1 was inactive against glycine receptor, its "non-classical" binding sites on α7 nAChR should be within the extracellular domain. Micromolar affinities and fast washout rates measured for ws-LYNX1 and its mutants are in contrast to nanomolar affinities and irreversibility of binding for α-bungarotoxin and similar

  10. Water-soluble LYNX1 Residues Important for Interaction with Muscle-type and/or Neuronal Nicotinic Receptors*

    Science.gov (United States)

    Lyukmanova, Ekaterina N.; Shulepko, Mikhail A.; Buldakova, Svetlana L.; Kasheverov, Igor E.; Shenkarev, Zakhar O.; Reshetnikov, Roman V.; Filkin, Sergey Y.; Kudryavtsev, Denis S.; Ojomoko, Lucy O.; Kryukova, Elena V.; Dolgikh, Dmitry A.; Kirpichnikov, Mikhail P.; Bregestovski, Piotr D.; Tsetlin, Victor I.

    2013-01-01

    Human LYNX1, belonging to the Ly6/neurotoxin family of three-finger proteins, is membrane-tethered with a glycosylphosphatidylinositol anchor and modulates the activity of nicotinic acetylcholine receptors (nAChR). Recent preparation of LYNX1 as an individual protein in the form of water-soluble domain lacking glycosylphosphatidylinositol anchor (ws-LYNX1; Lyukmanova, E. N., Shenkarev, Z. O., Shulepko, M. A., Mineev, K. S., D'Hoedt, D., Kasheverov, I. E., Filkin, S. Y., Krivolapova, A. P., Janickova, H., Dolezal, V., Dolgikh, D. A., Arseniev, A. S., Bertrand, D., Tsetlin, V. I., and Kirpichnikov, M. P. (2011) NMR structure and action on nicotinic acetylcholine receptors of water-soluble domain of human LYNX1. J. Biol. Chem. 286, 10618–10627) revealed the attachment at the agonist-binding site in the acetylcholine-binding protein (AChBP) and muscle nAChR but outside it, in the neuronal nAChRs. Here, we obtained a series of ws-LYNX1 mutants (T35A, P36A, T37A, R38A, K40A, Y54A, Y57A, K59A) and examined by radioligand analysis or patch clamp technique their interaction with the AChBP, Torpedo californica nAChR and chimeric receptor composed of the α7 nAChR extracellular ligand-binding domain and the transmembrane domain of α1 glycine receptor (α7-GlyR). Against AChBP, there was either no change in activity (T35A, T37A), slight decrease (K40A, K59A), and even enhancement for the rest mutants (most pronounced for P36A and R38A). With both receptors, many mutants lost inhibitory activity, but the increased inhibition was observed for P36A at α7-GlyR. Thus, there are subtype-specific and common ws-LYNX1 residues recognizing distinct targets. Because ws-LYNX1 was inactive against glycine receptor, its “non-classical” binding sites on α7 nAChR should be within the extracellular domain. Micromolar affinities and fast washout rates measured for ws-LYNX1 and its mutants are in contrast to nanomolar affinities and irreversibility of binding for α-bungarotoxin and

  11. The Novel 7 Nicotinic Acetylcholine Receptor Agonist N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]-7-[2-(methoxy)phenyl]-1-benzofuran-2-carboxamide Improves Working and Recognition Memory in Rodents

    NARCIS (Netherlands)

    Boess, F.G.; Vry, de J.; Erb, C.; Flessner, T.; Luithle, J.; Methfessel, C.; Schnizler, K.; Staay, van der F.J.; Kampen, van M.; Wiese, W.B.; Hendrix, M.; König, G.

    2007-01-01

    The relative contribution of alpha 4 beta 2, alpha 7 and other nicotinic acetylcholine receptor ( nAChR) subtypes to the memory enhancing versus the addictive effects of nicotine is the subject of ongoing debate. In the present study, we characterized the pharmacological and behavioral properties of

  12. The Novel 7 Nicotinic Acetylcholine Receptor Agonist N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]-7-[2-(methoxy)phenyl]-1-benzofuran-2-carboxamide Improves Working and Recognition Memory in Rodents

    NARCIS (Netherlands)

    Boess, F.G.; Vry, de J.; Erb, C.; Flessner, T.; Luithle, J.; Methfessel, C.; Schnizler, K.; Staay, van der F.J.; Kampen, van M.; Wiese, W.B.; Hendrix, M.; König, G.

    2007-01-01

    The relative contribution of alpha 4 beta 2, alpha 7 and other nicotinic acetylcholine receptor ( nAChR) subtypes to the memory enhancing versus the addictive effects of nicotine is the subject of ongoing debate. In the present study, we characterized the pharmacological and behavioral properties of

  13. Nicotine dependence and psychiatric disorders.

    Science.gov (United States)

    Salín-Pascual, Rafael J; Alcocer-Castillejos, Natasha V; Alejo-Galarza, Gabriel

    2003-01-01

    Nicotine addiction is the single largest preventable cause of morbidity and mortality in the Western World. Smoking is not any more just a bad habit, but a substance addiction problem. The pharmacological aspects of nicotine show that this substance has a broad distribution in the different body compartnents, due mainly to its lipophilic characteristic. There are nicotinic receptors as members of cholinergic receptors' family. They are located in neuromuscular junction and in the central nervous system (CNS). Although they are similar, pentameric structure with an ionic channel to sodium, there are some differences in the protein chains characteristics. Repeated administration of nicotine in rats, results in the sensitization phenomenon, which produces increase in the behavioral locomotor activity response. It has been found that most psychostimulants-induced behavioral sensitization through a nicotine receptor activation. Nicotine receptors in CNS are located mainly in presynaptic membrane and in that way they regulated the release of several neurotransmitters, among them acetylcholine, dopamine, serotonin, and norepinephrine. In some activities like sleep-wake cycle, nicotine receptors have a functional significance. Nicotine receptor stimulation promotes wake time, reduces both, total sleep time and rapid eye movement sleep (REMS). About nicotine dependence, this substance full fills all the criteria for dependence and withdrawal syndrome. There are some people that have more vulnerability for to become nicotine dependent, those are psychiatric patients. Among them schizophrenia, major depression, anxiety disorders and attention deficit disorder, represent the best example in this area. Nicotine may have some beneficial effects, among them are some neuroprotective effects in disorders like Parkinson's disease, and Gilles de la Tourette' syndrome. Also there are several evidences that support the role of nicotine in cognitive improvement functions like attention

  14. Effect of the Nicotinic α4β2-receptor Partial Agonist Varenicline on Non-invasive Brain Stimulation-Induced Neuroplasticity in the Human Motor Cortex.

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    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.

  15. Cooperative regulation of non-small cell lung carcinoma by nicotinic and beta-adrenergic receptors: a novel target for intervention.

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    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

  16. Nicotinic acetylcholine receptors (nAChRs) at zebrafish red and white muscle show different properties during development.

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    Ahmed, Kazi T; Ali, Declan W

    2016-08-01

    Nicotinic acetylcholine receptors (nAChRs) are highly expressed at the vertebrate neuromuscular junction (NMJ) where they are required for muscle activation. Understanding the factors that underlie NMJ development is critical for a full understanding of muscle function. In this study we performed whole cell and outside-out patch clamp recordings, and single-cell RT-qPCR from zebrafish red and white muscle to examine the properties of nAChRs during the first 5 days of development. In red fibers miniature endplate currents (mEPCs) exhibit single exponential time courses at 1.5 days postfertilization (dpf) and double exponential time courses from 2 dpf onwards. In white fibers, mEPCs decay relatively slowly, with a single exponential component at 1.5 dpf. By 2 and 3 dpf, mEPC kinetics speed up, and decay with a double exponential component, and by 4 dpf the exponential decay reverts back to a single component. Single channel recordings confirm the presence of two main conductance classes of nAChRs (∼45 pS and ∼65 pS) in red fibers with multiple time courses. Two main conductance classes are also present in white fibers (∼55 pS and ∼73 pS), but they exhibit shorter mean open times by 5 dpf compared with red muscle. RT-qPCR of mRNA for nicotinic receptor subunits supports a switch from γ to ε subunits in white fibers but not in red. Our findings provide a developmental profile of mEPC properties from red and white fibers in embryonic and larval zebrafish, and reveal previously unknown differences between the NMJs of these muscle fibers.© 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 916-936, 2016.

  17. A randomized exploratory trial of an α-7 nicotinic receptor agonist (TC-5619) for cognitive enhancement in schizophrenia.

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    Lieberman, Jeffrey A; Dunbar, Geoffrey; Segreti, Anthony C; Girgis, Ragy R; Seoane, Frances; Beaver, Jessica S; Duan, Naihua; Hosford, David A

    2013-05-01

    This exploratory trial was conducted to test the effects of an alpha7 nicotinic receptor partial agonist, TC-5619, on cognitive dysfunction and negative symptoms in subjects with schizophrenia. In the United States and India, 185 outpatients (18-60 years; male 69%; 46% tobacco users) with schizophrenia treated with quetiapine or risperidone monotherapy were randomized to 12 weeks of placebo (n=91) or TC-5619 (n=94; orally once daily 1 mg day 1 to week 4, 5 mg week 4 to 8, and 25 mg week 8 to 12). The primary efficacy outcome measure was the Groton Maze Learning Task (GMLT; executive function) of the CogState Schizophrenia Battery (CSB). Secondary outcome measures included: CSB composite score; Scale for Assessment of Negative Symptoms (SANS); Clinical Global Impression-Global Improvement (CGI-I); CGI-severity (CGI-S); and Subject Global Impression-Cognition. GMLT statistically favored TC-5619 (P=0.036) in this exploratory trial. SANS also statistically favored TC-5619 (P=0.030). No other secondary outcome measure demonstrated a drug effect in the total population; there was a statistically significant drug effect on working memory in tobacco users. The results were typically stronger in favor of TC-5619 in tobacco users and occasionally better in the United States than in India. TC-5619 was generally well tolerated with no clinically noteworthy safety findings. These results support the potential benefits of TC-5619 and alpha7 nicotinic receptor partial agonists for cognitive dysfunction and negative symptoms in schizophrenia.

  18. VdTX-1, a reversible nicotinic receptor antagonist isolated from venom of the spider Vitalius dubius (Theraphosidae).

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    Rocha-E-Silva, Thomaz A A; Rostelato-Ferreira, Sandro; Leite, Gildo B; da Silva, Pedro Ismael; Hyslop, Stephen; Rodrigues-Simioni, Léa

    2013-08-01

    Theraphosid spider venoms can block neurotransmission in vertebrate nerve-muscle preparations in vitro, but few of the components involved have been characterized. In this work, we describe the neuromuscular activity of venom from the Brazilian theraphosid Vitalius dubius and report the purification and pharmacological characterization of VdTX-1, a 728 Da toxin that blocks nicotinic receptors. Neuromuscular activity was assayed in chick biventer cervicis preparations and muscle responses to exogenous ACh and KCl were determined before and after incubation with venom or toxin. Changes in membrane resting potential were studied in mouse diaphragm muscle. The toxin was purified by a combination of filtration through Amicon® filters, cation exchange HPLC and RP-HPLC; toxin purity and mass were confirmed by mass spectrometry. Venom caused progressive neuromuscular blockade and muscle contracture; the blockade but not the contracture was reversible by washing. Venom attenuated contractures to exogenous ACh and KCl. Filtration yiel