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Rose P, Widder S, Looft J, Pickenhagen W, Ong CN, Whiteman M. Inhibition of peroxynitrite-mediated cellular toxicity, tyrosine nitration, and alpha1-antiproteinase inactivation by 3-mercapto-2-methylpentan-1-ol, a novel compound isolated from Allium cepa. Biochem Biophys Res Commun 2003; 302:397-402. [PMID: 12604361 DOI: 10.1016/s0006-291x(03)00193-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Peroxynitrite formation in vivo is implicated in numerous human diseases and there is considerable interest in the use of antioxidants and natural products such as thiols as "peroxynitrite scavengers". We therefore investigated the effects of a recently identified constituent of onions, 3-mercapto-2-methylpentan-1-ol (3-MP), for its ability to inhibit peroxynitrite-mediated processes in vitro and using cultured human cells and compared its effectiveness against glutathione. 3-MP significantly inhibited peroxynitrite-mediated tyrosine nitration and inactivation of alpha(1)-antiproteinase to a greater extent than glutathione at each concentration tested (15-500 microM). 3-MP also inhibited peroxynitrite-induced cytotoxicity, intracellular tyrosine nitration, and intracellular reactive oxygen species generation in human HepG2 cells in culture to a greater extent than glutathione. These data suggest that 3-MP has the potential to act as an inhibitor of ONOO(-)-mediated processes in vivo and that the antioxidant action of 3-MP deserves further study.
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Maneesri J, Azuma M, Torii S, Igarashi K, Ooshima H. Characterization of a Saccharomyces cerevisiae mutant with pseudohyphae and cloning of a gene complementing the mutation. Biosci Biotechnol Biochem 2003; 67:517-24. [PMID: 12723598 DOI: 10.1271/bbb.67.517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Screening for morphological mutants of a haploid strain of Saccharomyces cerevisiae was done on the basis of their cell-shape on a solid medium containing isoamyl alcohol, which causes cell elongation, to obtain information on the morphogenesis. Mutant J19, which had pseudohyphae in liquid medium even in the absence of isoamyl alcohol, had many elongated cells. Few reports exist of haploid cells growing as pseudohyphae in liquid culture. Cell-wall analysis showed that J19 had ordinary amounts of alkali-insoluble glucan and chitin, but that isoamyl alcohol in the medium caused structural changes in the cell wall. Addition of a DNA fragment that included the wild-type SCL1 gene to J19 complemented its morphological phenotype. Sequencing of J19 SCL1 showed that the glycine at position 226 in the Scl1 protein had been replaced by asparatic acid, suggesting that this mutation in the protein, a subunit of proteasomes, may be involved in the morphological change.
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Bigdai EV, Samoilov VO. Components of the intracellular cAMP system supporting the olfactory reception of amyl alcohol. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2003; 33:89-94. [PMID: 12617309 DOI: 10.1023/a:1021139617470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Experiments on isolated frog olfactory epithelium, using vital luminescent microscopy showed that the olfactory transduction of amyl alcohol is mediated by the intracellular cAMP signaling system. Increases in intracellular cAMP levels resulted from activation of adenylate cyclase type III via odorant-induced stimulation of G protein linked to it.
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Cook DJ, Hollowood TA, Linforth RST, Taylor AJ. Oral shear stress predicts flavour perception in viscous solutions. Chem Senses 2003; 28:11-23. [PMID: 12502520 DOI: 10.1093/chemse/28.1.11] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The perception of sweetness and flavour were studied in viscous solutions containing 50 g/l sucrose, 100 p.p.m. iso-amyl acetate and varying concentrations of three hydrocolloid thickeners (guar gum, lambda-carrageenan and hydroxypropylmethyl cellulose). Zero-shear viscosity of the samples ranged from 1 to 5000 mPas. Perception of both sweetness and aroma was suppressed at thickener concentrations above c* (coil overlap concentration, the point at which there is an abrupt increase in solution viscosity as thickener concentration is increased). Sensory data for the three hydrocolloids was only loosely correlated with their concentration relative to c* (c/c* ratio), particularly above c*. However, when perceptual data were plotted against the Kokini oral shear stress (tau), calculated from rheological measurements, data for the three hydrocolloids aligned to form a master-curve, enabling the prediction of flavour intensity in such systems. The fact that oral shear stress can be used to model sweetness and aroma perception supports the hypothesis that somatosensory tactile stimuli can interact with taste and aroma signals to modulate their perception.
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Seebungkert B, Lynch JW. Effects of polyunsaturated fatty acids on voltage-gated K+ and Na+ channels in rat olfactory receptor neurons. Eur J Neurosci 2002; 16:2085-94. [PMID: 12473076 DOI: 10.1046/j.1460-9568.2002.02288.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although the polyunsaturated fatty acids arachidonic acid (AA) and docosahexaenoic acid (DHA) are enriched in the olfactory mucosa, their possible contribution to olfactory transduction has not been investigated. This study characterized their effects on voltage-gated K+ and Na+ channels of rat olfactory receptor neurons. Physiological (3-10 microm) concentrations of AA and DHA potently and irreversibly inhibited the voltage-gated K+ current in a voltage-independent manner. In addition, both compounds significantly reduced the inhibitory potency of the odorants acetophenone and amyl acetate at these channels. By comparison, the steady-state effects of both AA and DHA on the voltage-gated Na+ channel were relatively weak, with half-maximal inhibition requiring approximately 35 microm of either compound. However, a surprising finding was that the initial application of 3 microm AA to a naïve neuron caused a strong but transient inhibition of the Na+ current. The channels became almost completely resistant to this inhibition within 1 min, and a 2-min wash in control solution was insufficient to restore the strong inhibitory effect. These observations suggest that polyunsaturated fatty acids have the potential to strongly influence the coding of odorant information by olfactory receptor neurons.
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Burne THJ, Rogers LJ. Chemosensory input and lateralization of brain function in the domestic chick. Behav Brain Res 2002; 133:293-300. [PMID: 12110462 DOI: 10.1016/s0166-4328(02)00009-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
One-day old domestic chicks (Gallus gallus domesticus) show concentration-dependent behavioural responses to olfactory cues. In the present study we investigated the lateralized olfactory responses of 1-day-old chicks to the odours of eugenol and iso-amyl acetate. In experiment 1 different concentrations of each odour were presented in repeated trials to chicks housed individually. The odours were presented together with a small coloured bead at which the chick pecked. When tested with the highest concentration of eugenol (100% v/v), the chicks demonstrated more head shaking when their left nostril was occluded (RN; right nostril in use) than when their right nostril was occluded (LN; left nostril in use). No such lateralization occurred in response to iso-amyl acetate. This result was confirmed in a second experiment in which the chicks were tested with unscented stimuli, 100% eugenol and 100% isoamyl acetate. In experiment 3 we found that occluding both the chicks' nostrils abolished the head shaking response to eugenol and to iso-amyl acetate. Thus, the chicks' head shaking responses to the odorants eugenol and iso-amyl acetate are mediated primarily by inputs from within the nasal cavity, and not by oral or occular inputs. The present results are consistent with the hypothesis that there is lateralization to olfactory cues and that it is dependent on the involvement of receptors inside the nasal cavity. We suggest that differences in lateralized olfactory responses to different odours are affected by the relative involvement of intranasal olfactory and trigeminal chemoreceptors.
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Martin JV, Bilgin NM, Iba MM. Influence of oxygenated fuel additives and their metabolites on the binding of a convulsant ligand of the gamma-aminobutyric acid(A) (GABA(A)) receptor in rat brain membrane preparations. Toxicol Lett 2002; 129:219-26. [PMID: 11888705 DOI: 10.1016/s0378-4274(02)00020-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
As a foundation for evaluating potential mechanisms of the neurological effects (e.g. headache, nausea, dizziness) of some octane boosters, we studied the gamma-aminobutyric acid(A) (GABA(A)) receptor in a series of binding assays in membranes from rat brain. The GABA(A) receptor was probed using the radioligand [3H]t-butylbicycloorthobenzoate ([3H]TBOB) which binds to the convulsant recognition site of the receptor. The results demonstrated that the short-chain t-ethers and their t-alcohol metabolites inhibit binding at the convulsant site of the GABA(A) receptor. The potency of the inhibition tended to correlate with carbon chain length. For agents having an equal number of carbon atoms, potency of inhibition of [3H]TBOB binding was greater in magnitude for the alcohols than for the ethers. The descending rank order of potency for the ethers and alcohols were as follows, t-amyl alcohol (TAA); t-amyl-methyl ether (TAME); ethyl-t-butyl ether (ETBE)>t-butyl alcohol (TBA)>methyl-t-butyl ether (MTBE)>ethanol. In additional saturation binding assays, MTBE reduced apparent density of convulsant binding (B(max)).
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Kemenes I, Kemenes G, Andrew RJ, Benjamin PR, O'Shea M. Critical time-window for NO-cGMP-dependent long-term memory formation after one-trial appetitive conditioning. J Neurosci 2002; 22:1414-25. [PMID: 11850468 PMCID: PMC6757551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
The nitric oxide (NO)-cGMP signaling pathway is implicated in an increasing number of experimental models of plasticity. Here, in a behavioral analysis using one-trial appetitive associative conditioning, we show that there is an obligatory requirement for this pathway in the formation of long-term memory (LTM). Moreover, we demonstrate that this requirement lasts for a critical period of approximately 5 hr after training. Specifically, we trained intact specimens of the snail Lymnaea stagnalis in a single conditioning trial using a conditioned stimulus, amyl-acetate, paired with a salient unconditioned stimulus, sucrose, for feeding. Long-term associative memory induced by a single associative trial was demonstrated at 24 hr and shown to last at least 14 d after training. Tests for LTM and its dependence on NO were performed routinely 24 hr after training. The critical period when NO was needed for memory formation was established by transiently depleting it from the animals at a series of time points after training by the injection of the NO-scavenger 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide (PTIO). By blocking the activity of NO synthase and soluble guanylyl cyclase enzymes after training, we provided further evidence that LTM formation depends on an intact NO-cGMP pathway. An electrophysiological correlate of LTM was also blocked by PTIO, showing that the dependence of LTM on NO is amenable to analysis at the cellular level in vitro. This represents the first demonstration that associative memory formation after single-trial appetitive classical conditioning is dependent on an intact NO-cGMP signaling pathway.
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Gerasimov MR, Schiffer WK, Marstellar D, Ferrieri R, Alexoff D, Dewey SL. Toluene inhalation produces regionally specific changes in extracellular dopamine. Drug Alcohol Depend 2002; 65:243-51. [PMID: 11841896 DOI: 10.1016/s0376-8716(01)00166-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of the present study was to investigate the effect of toluene inhalation on dopaminergic transmission in two distinct brain areas presumably involved in mediating the reward processes important for toluene abuse. Extracellular dopamine (DA) levels were measured in prefrontal cortex (PFC) and nucleus accumbens (NACC) of freely moving rats using in vivo microdialysis. Inhalation of a behaviorally relevant concentration of toluene (3000 ppm) produced a significant increase in the PFC but not in the NACC. However, the odorant isoamyl acetate, increased PFC DA levels by only 37%, significantly less than the 96% increase observed following toluene exposure. When toluene inhalation was combined with cocaine administration (20 mg/kg i.p.), the response to the combined challenge was not different from the response to toluene alone in the PFC. However, the combination of these two drugs produced a supradditive response of 802% in the NACC, compared with the 450% increase observed following cocaine alone. Recent reports indicate that toluene influences the function of several ionotropic receptors in a subunit specific manner. As further evidence of specific effects, our results indicate regionally specific changes in dopaminergic transmission following toluene exposure.
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Anselmi C, Ettorre A, Andreassi M, Centini M, Neri P, Di Stefano A. In vitro induction of apoptosis vs. necrosis by widely used preservatives: 2-phenoxyethanol, a mixture of isothiazolinones, imidazolidinyl urea and 1,2-pentanediol. Biochem Pharmacol 2002; 63:437-53. [PMID: 11853695 DOI: 10.1016/s0006-2952(01)00910-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Preservatives are added to many final products, such as detergents, cosmetics, pharmaceuticals and vaccines. We conducted an in vitro investigation of the apoptosis- and necrosis-inducing potential of brief applications (10 min) of four common preservatives: ethylene glycol monophenyl ether, 2-phenoxyethanol (EGPE), imidazolidinyl urea (IMU), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMI/MI), and 1,2-pentanediol, a "preservative-non-preservative" best known as pentylene glycol. Using HL60 cells, we monitored the kinetics of cell toxicity with the MTT test and analysed extranuclear end points of apoptosis, i.e. phosphatidylserine exposure and nuclear fragmentation. Preservative treatment resulted in a dose-dependent decrease of cell viability. The mode of cell death was dose-dependent: necrosis occurred at high concentrations while apoptosis, shown by DNA laddering, DNA sub-diploid peak and caspase-3 activation, occurred at lower concentrations 0-24hr after exposure to a single dose: CMI/MI induced apoptosis at low concentrations (0.001-0.01%) and necrosis at high concentrations (0.5-0.1%); IMU and EGPE required higher concentrations to induce apoptosis (IMU 0.01-0.1% and EGPE 0.01-0.5%) or necrosis (IMU 0.5-1% and EGPE only at 1%). PG induced apoptosis only at 5%. Externalization of PS, a hallmark of apoptosis, occurred early in HL60 treated with low concentrations of CMI/MI and EGPE and was concomitant with the subdiploid peak in HL60 treated with PG. However, it did not occur in HL60 treated with IMU. In conclusion, at appropriate concentrations, each of the four preservatives modulates the apoptotic machinery by a caspase-dependent mechanism. Thus, apoptosis could be a good parameter to evaluate the cytoxicity of these chemical compounds.
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Abstract
The study of olfactory lateralization processes in humans has given rise to many publications, but the resulting data have not been homogeneous. Sensorial cerebral asymmetry depends on several factors (nature of task, characteristics of subjects, etc.) and could also depend on the quality of the stimulus, especially in olfaction. This field appears to be widely unexplored and the quality of odor is a complex property. The aim of this study was to investigate variations in psychophysiological measurements (bilateral electrodermal recordings) related to the quality of odors. Electrodermal asymmetries were used as a function of differential hemispheric activation. Two major characteristics of odor were explored, the hedonic valence (pleasant/unpleasant) and the trigeminal component (irritant/non-irritant). The results obtained in a sample of 30 right-handed subjects (15 males and 15 females) showed a predominance of the right hemisphere in the treatment of olfactory information not depending on the quality of odor, except the trigeminal-nerve activation.
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62
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Franklin AJ, Grégoir JC. Dose-dependent response and preliminary observations on attraction range of Ips typographus to pheromones at low release rates. J Chem Ecol 2001; 27:2425-35. [PMID: 11789949 DOI: 10.1023/a:1013619313415] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Responses of the European spruce bark beetle, 1. typographus (Coleoptera: Scolytidae), to low release-rate pheromones were investigated in two experiments in a spruce forest at Wellin, southern Belgium. Dose-response of the beetle was first examined in a trapping experiment in August 1999. The major pheromone components of L. typographus, (S)-cis-verbenol (cV) and 2-methyl-3-buten-2-ol (MB) were released from window traps. Five treatments were replicated five times: (1) blank trap, (2) 0.03 and 1.2, (3) 0.11 and 4.5, (4) 0.34 and 15.2 mg/day of cV and MB, respectively, and (5) Pheroprax. Trap catches increased linearly as a function of increasing release rates of cV and MB. A second study aimed at making preliminary observations on the attraction range of the pheromones as compared to Pheroprax. A release-recapture experiment was carried out in May 2000: four trap-trees located 50 m away from a central release platform were equipped with window traps baited with increasing release rates, tested in separate releases: 0.03 and 1.2; 0.11 and 4.5; 0.34 and 15.2 mg/day of cV and MB, respectively, and Pheroprax. Recaptures increased with the release rate. Trap catches were different at lower release rates, but not between the release rate of 15.2 mg/day of MB and Pheroprax. Variations in captures in relation to wind parameters showed persistently random flight at the lower release rates. Significant upwind flight was observed for Pheroprax only. These results imply that trap interference existed for Pheroprax and suggest that its attraction range may be greater than 50 m.
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63
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Ashe MP, Slaven JW, De Long SK, Ibrahimo S, Sachs AB. A novel eIF2B-dependent mechanism of translational control in yeast as a response to fusel alcohols. EMBO J 2001; 20:6464-74. [PMID: 11707417 PMCID: PMC125737 DOI: 10.1093/emboj/20.22.6464] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Fusel alcohols are natural products of amino acid catabolism in the yeast Saccharomyces cerevisiae that cause morphological changes similar to those seen during pseudohyphal growth. We have discovered that certain of these alcohols, including butanol and isoamyl alcohol, bring about a rapid inhibition of translation at the initiation step. This inhibition is strain specific and is not explained by previously described translational control pathways. Using genetic mapping, we have identified a proline to serine allelic variation at amino acid 180 of the GCD1 gene product as the genetic locus that allows translational regulation upon butanol addition. Gcd1p forms part of the eIF2B guanine nucleotide complex that is responsible for recycling eIF2-GDP to eIF2-GTP. This represents one of the key limiting steps of translation initiation and we provide evidence that fusel alcohols target eIF2B in order to bring about translational regulation.
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Shishkina LN, Safatov AS, Sergeev AN, Zhukov VA, Bulychev LE, P'iankov OV, Poryvaev VD, P'iankova OG, Buriak GA, Goncharova EP. [Mechanisms of action of aerosol preparations based on Abies siberica polyprenols in experimental influenza infection]. Vopr Virusol 2001; 46:28-33. [PMID: 11785384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
Humoral and cellular mechanisms of Abies sibirica polyprenol effects on nonspecific resistance of mice to influenza A/Aichi/2/68 virus were investigated. Two aerosol doses of polyprenols had a high protective effect in mice challenged with influenza virus. Aerosol polyprenol preparations in the studied doses induced no interferon or tumor necrosis factor production in the lungs. Lung macrophage counts and capacity to produce superoxide anion radicals increased in survivors after influenza in comparison with intact animals. Double aerosol administration of polyprenols prior to influenza infection promoted an increase in the thymus weight, bronchoalveolar tract cell counts (predominantly at the expense of lymphocytes), and of superoxide-producing potential of macrophages, which, in turn, can contribute to improvement of the defense potential of the organism towards influenza virus.
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Zuo Y, Aistrup GL, Marszalec W, Gillespie A, Chavez-Noriega LE, Yeh JZ, Narahashi T. Dual action of n-alcohols on neuronal nicotinic acetylcholine receptors. Mol Pharmacol 2001; 60:700-11. [PMID: 11562431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Alcohol is known to modulate the activity of a variety of neuroreceptors and ion channels. Recently, neuronal nicotinic acetylcholine receptors (nnAChRs) have become a specific focus of study because not only are they potently modulated by alcohol but also they regulate the release of various transmitters, including gamma-aminobutyric acid (GABA) and dopamine, which play an important role in the behavioral effects of ethanol. Whereas the potency of normal alcohols (n-alcohols) to potentiate GABA(A) receptors and to inhibit N-methyl-D-aspartate receptors increases with carbon chain length, we have found that n-alcohols, depending on the carbon chain length, exert a dual action, potentiation and inhibition, on nnAChRs in primary cultured rat cortical neurons. The mechanism of dual action of n-alcohols on nnAChRs was further analyzed using human embryonic kidney cells expressing the alpha 4 beta 2 subunits. Shorter chain alcohols from methanol to n-propanol potentiated acetylcholine (ACh)-induced currents, whereas longer chain alcohols from n-pentanol to n-dodecanol inhibited the currents. n-Butanol either potentiated or inhibited the currents depending on the concentrations of ACh and butanol. The parameters for both potentiation (log EC(200)) and inhibition (log IC(50)) were linearly related to carbon number, albeit with different slopes. The slope for potentiation was -0.299, indicating a change in free energy change (Delta Delta G) of 405 cal/mol/methylene group, whereas the slope for inhibition was -0.584, indicating a Delta Delta G of 792 cal/mol. These results suggest that potentiating and inhibitory actions are exerted through two different binding sites. Ethanol decreased the potency of n-octanol to inhibit ACh currents, possibly resulting from an allosteric mechanism.
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66
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Devaud JM, Acebes A, Ferrús A. Odor exposure causes central adaptation and morphological changes in selected olfactory glomeruli in Drosophila. J Neurosci 2001; 21:6274-82. [PMID: 11487650 PMCID: PMC6763130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
In an attempt to correlate behavioral and neuronal changes, we examined the structural and functional effects of odor exposure in Drosophila. Young adult flies were exposed to a high concentration of the selected odor, usually benzaldehyde or isoamyl acetate, for 4 d and subsequently tested for their olfactory response to a variety of odorants and concentrations. The behavioral response showed specific adaptation to the exposed odor. By contrast, olfactory transduction, as measured in electroantennograms, remained normal. In vivo volume measurements were performed on olfactory glomeruli, the anatomical and functional units involved in odor processing. Pre-exposed flies exhibited volume reduction of certain glomeruli, in an odor-selective manner. Of a sample of eight glomeruli measured, dorsal medial (DM) 2 and ventral (V) were affected by benzaldehyde exposure, whereas DM6 was affected by isoamyl acetate. Estimation of the number of synapses indicates that volume reduction involves synapse loss that can reach 30% in the V glomerulus of flies adapted to benzaldehyde. Additional features of odorant-induced adaptation, including concentration dependence and perdurance, also show correlation, because both effects are elicited by high odor concentrations and are long-lasting (>1 week). Finally, the dunce mutant fails to develop behavioral adaptation as well as morphological changes in the olfactory glomeruli after exposure. These neural changes thus appear to require the cAMP signaling pathway.
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67
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Seebungkert B, Lynch JW. A common inhibitory binding site for zinc and odorants at the voltage-gated K(+) channel of rat olfactory receptor neurons. Eur J Neurosci 2001; 14:353-62. [PMID: 11553285 DOI: 10.1046/j.0953-816x.2001.01646.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study compared the effects of zinc and odorants on the voltage-gated K(+) channel of rat olfactory neurons. Zinc reduced current magnitude, depolarized the voltage activation curve and slowed activation kinetics without affecting inactivation or deactivation kinetics. Zinc inhibition was potentiated by the NO compound, S-nitroso-cysteine. The pH- and diethylpyrocarbonate-dependence of zinc inhibition suggested that zinc acted by binding to histidine residues. Cysteine residues were eliminated as contributing to the zinc-binding site. The odorants, acetophenone and amyl acetate, also reduced current magnitude, depolarized the voltage activation curve and selectively slowed activation kinetics. Furthermore, the diethylpyrocarbonate- and pH-dependence of odorant inhibition implied that the odorants also bind to histidine residues. Zinc inhibitory potency was dramatically diminished in the presence of odorants, implying competition for a common binding site. These observations indicate that the odorants and zinc share a common inhibitory binding site on the external surface of the voltage-gated K(+) channel.
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Li Y, Wang K, Yu T, Zhao B, Li J, Zhang S, Zhao X. [The expression of uridine diphosphate glucuronosyltransferase mRNA regulated by alcohol]. ZHONGHUA GAN ZANG BING ZA ZHI = ZHONGHUA GANZANGBING ZAZHI = CHINESE JOURNAL OF HEPATOLOGY 2001; 9:172-4. [PMID: 11412396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
OBJECTIVE To investigate whether ethanol and isopentanol could modulate the drug metabolism by regulating uridine diphosphate glucuronosyltransferase (UGT) expression in rat livers and cultured rat hepatocytes. METHODS Rat livers and primary rat hepatocyte cultures have been used to determine the mRNA levels of five UGT isoenzymes following treatment with ethanol and isopentanol. RESULTS Following treatment with alcohol in rats, UGT1A1 mRNA and UGT1A5 mRNA were increased to a mean of 177% and 166% of control, respectively. The mRNA levels of UGT2B1 and UGT2B3 were also increased in alcohol-treated rats to 178% and 132% of control, respectively. Incubation of hepatocytes with ethanol and isopentanol significantly increased the mRNA expression of UGT1A1, UGT1A5, UGT2B1 and UGT2B3 mRNA. CONCLUSIONS The expression of UGT can be regulated by ethanol and isopentanol. As a result, chronic alcohol consumption may modify the metabolism of numerous endogenous and exogenous compounds, in particular some drugs, which are substrates of these UGT isoenzymes.
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69
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Bigdaĭ EV, Samoĭlov VO. [Components of the intracellular cyclic AMP system maintaining olfactory reception of amyl alcohol]. ROSSIISKII FIZIOLOGICHESKII ZHURNAL IMENI I.M. SECHENOVA 2001; 87:821-8. [PMID: 11534209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
In experiments on isolated olfactory epithelium, cAMP was shown to have an intracellular signal system which participates in pentanol olfaction transduction. Increase in the intracellular cAMP level is associated with adenylate cyclase activation due to G-protein stimulation by odorant coupled with it.
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70
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Kawai F, Miyachi E. Enhancement by T-type Ca2+ currents of odor sensitivity in olfactory receptor cells. J Neurosci 2001; 21:RC144. [PMID: 11319242 PMCID: PMC6762504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Mechanisms underlying action potential initiation in olfactory receptor cells (ORCs) during odor stimulation were investigated using conventional and dynamic patch-clamp recording techniques. Under current-clamp conditions, action potentials generated by a least effective odor-induced depolarization were almost completely blocked by 0.1 mm Ni(2+), a T-type Ca(2+) channel blocker, but not by 0.1 mm Cd(2+), a high voltage-activated Ca(2+) channel blocker. Under voltage-clamp conditions, depolarizing voltage steps induced a fast transient inward current, which consisted of Na(+) (I(Na)) and T-type Ca(2+) (I(Ca,T)) currents. The amplitude of I(Ca,T) was approximately one-fourth of that of I(Na) (0.23 +/- 0.03, mean +/- SEM). Because both I(Na) and I(Ca,T) are known to show rapid inactivation, we examined how much I(Na) and I(Ca,T) are activated during the gradually depolarizing initial phase of receptor potentials. The ratio of I(Ca,T)/I(Na) during a ramp depolarization at the slope of 0.5 mV/msec was 0.56 +/- 0.03. Using the dynamic patch-clamp recording technique, we also recorded I(Ca,T) and I(Na) during the generation of odor-induced action potentials. This ratio of I(Ca,T)/I(Na) was 0.54 +/- 0.04. These ratios were more than twice as large as that (0.23) obtained from the experiment using voltage steps, suggesting that I(Ca,T) carries significant amount of current to generate the action potentials. We conclude that I(Ca,T) contributes to enhance odor sensitivity by lowering the threshold of spike generation in ORCs.
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71
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Yee KK, Wysocki CJ. Odorant exposure increases olfactory sensitivity: olfactory epithelium is implicated. Physiol Behav 2001; 72:705-11. [PMID: 11337002 DOI: 10.1016/s0031-9384(01)00428-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exposure-induced shifts in sensitivity to odors may involve peripheral and/or central components of the olfactory system. The ability to disconnect the olfactory epithelium from the bulbs provides a unique opportunity to examine how odorant exposure affects each component. In one experiment, odor thresholds were established for either amyl acetate or androstenone. The mice were then exposed for 10 days to the same test odorant for which a threshold was obtained. After exposure, sensitivity to the odorant increased relative to preexposure levels. The mice then underwent bilateral olfactory nerve transection (BNX). When both groups of mice were tested 45-50 days after recovery from surgery and return of olfactory function, increased sensitivity to the exposed odorant persisted; however, 121-203 days after surgery, sensitivity returned to preexposure levels. Another experiment was similar to the first except that mice were exposed to an odorant, either amyl acetate or androstenone, for 10 days beginning 1 day after BNX or sham surgery. When the mice were tested 45-50 days after surgery, sensitivity to the exposed odorant was increased relative to preexposure levels, whereas sensitivity to the nonexposed odorant remained at preexposure levels. Although further work is needed to determine the precise mechanism(s) underlying shifts in sensitivity to odors, these studies provide additional evidence for peripheral involvement in exposure-induced sensitization to odorants and demonstrate the remarkable capacity of the olfactory system to maintain or even regain sensitivity after injury.
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72
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Margrie TW, Sakmann B, Urban NN. Action potential propagation in mitral cell lateral dendrites is decremental and controls recurrent and lateral inhibition in the mammalian olfactory bulb. Proc Natl Acad Sci U S A 2001; 98:319-24. [PMID: 11120888 PMCID: PMC14588 DOI: 10.1073/pnas.98.1.319] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the mammalian main olfactory bulb (MOB), the release of glutamate from lateral dendrites of mitral cells onto the dendrites of granule cells evokes recurrent and lateral inhibition of mitral cell activity. Whole-cell voltage recordings in the mouse MOB in vivo and in vitro show that recurrent and lateral inhibition together control the number, duration, and onset of odor-evoked action potential (AP) firing in mitral cells. APs in mitral cells propagate into the lateral dendrites and evoke a transient increase in dendritic calcium concentration ([Ca2+]), which is decremental with distance from the soma, and increases with AP number. These results suggest that the extent of AP propagation in lateral dendrites of mitral cells, along with the concomitant dendritic Ca(2+) transient, controls the amplitude of lateral and recurrent inhibition and thus is a critical determinant of odor-specific AP patterns in the MOB.
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73
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Yamada H, Nakatani K. Odorant-induced hyperpolarization and suppression of cAMP-activated current in newt olfactory receptor neurons. Chem Senses 2001; 26:25-34. [PMID: 11124212 DOI: 10.1093/chemse/26.1.25] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although many studies have reported that odorants can elicit inhibitory responses as well as excitatory responses in vertebrate olfactory receptor neurons, the cellular mechanisms that underlie this inhibition are unclear. Here we examine the inhibitory effect of odorants on newt olfactory receptor neurons using whole cell patch clamp recording. At high concentrations, odorant stimulation decreased the membrane conductance and inhibited depolarization. Various odorants (anisole, isoamyl acetate, cineole, limonene and isovaleric acid) suppressed the depolarizing current in a dose-dependent manner. Furthermore, one odorant could suppress the depolarization caused by another odorant. The depolarization caused by isoamyl acetate was inhibited by anisole in cells that were excited by isoamyl acetate but not by anisole. Odorants were able to hyperpolarize cells that were depolarized by cAMP-induced conductance. Given that this inhibitory effect of odorants can affect excitation caused by other odorants, we suggest that it might play a role in coding odorants in olfactory receptor neurons.
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74
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Wallace KJ, Rosen JB. Predator odor as an unconditioned fear stimulus in rats: elicitation of freezing by trimethylthiazoline, a component of fox feces. Behav Neurosci 2000; 114:912-22. [PMID: 11085605 DOI: 10.1037/0735-7044.114.5.912] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Four experiments tested whether an odor from a rat predator can unconditionally elicit a fear response in rats. In a large chamber, rats displayed fear-related behaviors to trimethylthiazoline (TMT, a volatile compound isolated from fox feces), including avoidance and immobility, while showing less exploratory behavior. In a smaller chamber, TMT induced a species-typical fear response, freezing, whereas other odors did not. In addition, TMT systematically elicited more freezing as the amount of TMT increased. Moreover, there was no within-sessions or between-sessions habituation of freezing to TMT, nor did TMT promote contextual conditioning. The results indicate that the predator odor, TMT, can induce a fear-related behavioral response in rats that is controllable and quantifiable, suggesting that TMT-induced freezing may be a useful paradigm for a neurobehavioral system analysis of ecologically relevant, unconditioned fear.
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75
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Peoples RW, Stewart RR. Alcohols inhibit N-methyl-D-aspartate receptors via a site exposed to the extracellular environment. Neuropharmacology 2000; 39:1681-91. [PMID: 10884550 DOI: 10.1016/s0028-3908(00)00067-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-Methyl-D-aspartate (NMDA) receptors are important CNS target sites of alcohols, but the site and mechanism of action of alcohols on NMDA receptors remains unclear. In CHO-K1 cells transfected with NR1/NR2B NMDA receptor subunits, ethanol inhibited NMDA-activated current with an IC(50) of 138 mM. Truncation of the intracellular C-terminal domain of the NR1 subunit (NR1T) did not alter ethanol sensitivity when combined with the NR2B subunit, but a similar truncation of the NR2B subunit (NR2BT) slightly enhanced ethanol sensitivity of receptors formed from coexpression with either NR1 or NR1T subunits. 1-Pentanol applied externally inhibited NMDA receptors with an IC(50) of 9.9 mM, but intracellular application of 1-pentanol (25 mM) did not alter NMDA receptor inhibition by externally applied ethanol or 1-pentanol. In addition, the amplitude of NMDA-activated current did not decrease during the time required for 1-pentanol (25 mM) to diffuse throughout the cytoplasm. Ethanol did not inhibit NMDA receptors when bath-applied in cell-attached patches or when applied to the cytoplasmic face of inside-out membrane patches. These results appear to be best explained by an action of alcohols on the NMDA receptor-channel protein, at a site located in a domain exposed to, or only accessible from, the extracellular environment.
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