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Kitano Y, Wakimoto S, Tamura S, Kubota K, Domon Y, Arakawa N, Saito M, Sava B, Buisson B. Effects of mirogabalin, a novel ligand for the α₂δ subunit of voltage-gated calcium channels, on N-type calcium channel currents of rat dorsal root ganglion culture neurons. Pharmazie 2019; 74:147-149. [PMID: 30961679 DOI: 10.1691/ph.2019.8833] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 09/29/2022]
Abstract
Mirogabalin, which is a novel ligand for the α₂δ subunit of voltage-gated calcium channels, is being developed for treating neuropathic pain including diabetic peripheral neuropathy and postherpetic neuralgia. Mirogabalin possesses unique α₂δ subunit binding characteristics and has potent and long-lasting analgesic effects in neuropathic pain models. In the present study, we investigated the effects of mirogabalin on N-type calcium channel currents of the rat dorsal root ganglion (DRG) culture neurons using the whole-cell patch clamp technique. Small or medium DRG neurons were isolated from Sprague-Dawley rats and were incubated for 20 to 24 h with mirogabalin or pregabalin. The DRG neurons were depolarised from a holding potential of -40 mV to +40 mV in steps of 10 mV for 220 ms, and elicited N-type calcium channel currents were recorded. The N-type calcium channel currents were verified by sensitivity to ω-conotoxin GVIA, a selective N-type calcium channel blocker. Mirogabalin inhibited the calcium channel currents of rat DRG neurons at 50 μM, and pregabalin inhibited them at 200 μM. Mirogabalin and pregabalin showed significant differences in the peak current densities at depolarisation to -20 and -10 mV when compared with that shown by the vehicle control. In conclusion, mirogabalin inhibits N-type calcium channel currents in rat DRG culture neurons. The potent and long-lasting analgesic effects of mirogabalin are thought to be associated with its potent and selective binding to α₂δ-1 subunits and following functional inhibition of calcium channel currents.
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Attia J, Blanc A, Hassnaoui M, Rehailia M, Buisson B. A Neurosecretory Phenomenon in Some Cerebral Nervous Cells of the Land Snail Helix aspersa maxima (Mollusca, Gastropoda), and Its Relationship to Circadian Locomotor and Food-Intake Activities. BIOL RHYTHM RES 2010. [DOI: 10.1076/brhm.29.4.329.1430] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- J. Attia
- a Laboratoire for Applied Biology, St. Etienne, France
| | - A. Blanc
- a Laboratoire for Applied Biology, St. Etienne, France
| | - M. Hassnaoui
- a Laboratoire for Applied Biology, St. Etienne, France
| | - M. Rehailia
- a Laboratoire for Applied Biology, St. Etienne, France
| | - B. Buisson
- a Laboratoire for Applied Biology, St. Etienne, France
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Hassnaoui M, Pupier R, Attia J, Blanc A, Beauchaud M, Buisson B. Some Tools to Analyze Changes of Rhythms in Biological Time Series. BIOL RHYTHM RES 2010. [DOI: 10.1076/brhm.29.4.353.1431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Schaller S, Buisson B, Souktani R, D'Anglemont A, Michaud M, Drouot C, Berdeaux A, Pruss R. Cardioprotective effects of TRO40303. J Mol Cell Cardiol 2007. [DOI: 10.1016/j.yjmcc.2007.03.657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Blanc A, Vivien-Roels B, Pévet P, Attia J, Buisson B. Melatonin and 5-methoxytryptophol (5-ML) in nervous and/or neurosensory structures of a gastropod mollusc (Helix aspersa maxima): synthesis and diurnal rhythms. Gen Comp Endocrinol 2003; 131:168-75. [PMID: 12679093 DOI: 10.1016/s0016-6480(03)00008-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Daily patterns of melatonin and 5-methoxytryptophol (5-ML) concentrations and of aryl alkylamine N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT) activities have been measured in the cerebroid ganglions, visceral ganglions, and ocular tentacles of the gastropod mollusc Helix aspersa maxima. Melatonin concentrations are very low in all the studied structures, except a small peak at the end of the night in the cerebroid ganglions. 5-ML, which is quite undetectable in the cerebroid and visceral ganglions, shows clear daily variations in the ocular tentacles with low values in the middle of the light period and high values during the night. These results are opposite to what is known on daily variations of 5-ML in vertebrates. AA-NAT activity was not detected, while the presence of an HIOMT-like activity supports the hypothesis that 5-ML is synthesized in the ocular tentacles. The temporal relationships existing between the 5-ML rhythm in the ocular tentacles and the hemolymph suggest that 5-ML could be released in the general circulation. These preliminary results suggest that 5-ML could be an informative molecule involved in adaptative processes in the snail and they reinforce the hypothesis that the different 5-methoxyindoles could be implicated in the integration of environmental information.
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Affiliation(s)
- A Blanc
- Laboratoire de Biologie animale et appliquée, Faculté des Sciences et Techniques, Université Jean Monnet, 23 rue Paul Michelon, 42023 St-Etienne Cedex 2, France.
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Denis C, Hemati M, Chulia D, Lanne JY, Buisson B, Daste G, Elbaz F. A model of surface renewal with application to the coating of pharmaceutical tablets in rotary drums. POWDER TECHNOL 2003. [DOI: 10.1016/s0032-5910(02)00262-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Villiger Y, Szanto I, Jaconi S, Blanchet C, Buisson B, Krause KH, Bertrand D, Romand JA. Expression of an alpha7 duplicate nicotinic acetylcholine receptor-related protein in human leukocytes. J Neuroimmunol 2002; 126:86-98. [PMID: 12020960 DOI: 10.1016/s0165-5728(02)00057-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We examined the potential expression and function of alpha7 nicotinic acetylcholine receptors (nAChRs) in leukocytes. RT-PCR with alpha7 specific primers revealed the presence of the receptor mRNA in leukocytes. Immunoblotting and immunofluorescence experiments demonstrated the expression of a protein that is recognized by alpha7 specific antibodies. However, nicotine and acetylcholine (ACh) failed to elicit current in leukocytes. Binding experiments with alpha-bungarotoxin rhodamine conjugated were negative, illustrating the absence of a high-affinity binding site. RT-PCR analysis revealed the selective expression of the dupalpha7 mRNA. These data indicate that leukocytes express in their membrane the dupalpha7 protein but its physiological role remains to be identified.
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Affiliation(s)
- Y Villiger
- Department of Physiology, Faculty of Medicine, CMU, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland
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Lukas RJ, Lucero L, Buisson B, Galzi JL, Puchacz E, Fryer JD, Changeux JP, Bertrand D. Neurotoxicity of channel mutations in heterologously expressed alpha7-nicotinic acetylcholine receptors. Eur J Neurosci 2001; 13:1849-60. [PMID: 11403678 DOI: 10.1046/j.0953-816x.2001.01560.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nicotinic acetylcholine receptors (nAChR) composed of chick alpha7 subunits mutated to threonine at amino acid valine-251 in the putative channel-lining M2 domain were expressed heterologously in several neuron-like and non-neuronal mammalian cell lines. Expression of mutant alpha7-nAChR is toxic to neuron-like cells of the human neuroblastoma cell lines SH-SY5Y and IMR-32, but not to several other cell types. Growth in the presence of the alpha7-nAChR antagonist methyllycaconitine (MLA) protects against neurotoxicity, as does gradual downregulation of functional, mutant alpha7-nAChR in surviving transfected SH-SY5Y cells. Relative to wild-type alpha7-nAChR, functional alpha7-nAChR mutants show a higher affinity for agonists, slower rates of desensitization, and sensitivity to dihydro-beta-erythroidine (DHbetaE) as an agonist, but they retain sensitivity to MLA as a competitive antagonist. These findings demonstrate that expression of hyperfunctional, mutant forms of Ca2+-permeable alpha7-nAChR is toxic to neuron-like cells.
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Affiliation(s)
- R J Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013, USA.
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Buisson B, Bertrand D. Chronic exposure to nicotine upregulates the human (alpha)4((beta)2 nicotinic acetylcholine receptor function. J Neurosci 2001; 21:1819-29. [PMID: 11245666 PMCID: PMC6762627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Widely expressed in the brain, the alpha4beta2 nicotinic acetylcholine receptor (nAChR) is proposed to play a major role in the mechanisms that lead to and maintain nicotine addiction. Using the patch-clamp technique and pharmacological protocols, we examined the consequences of long-term exposure to 0.1-10 micrometer nicotine in K-177 cells expressing the major human brain alpha4beta2 receptor. The acetylcholine dose-response curves are biphasic and revealed both a high- and a low-affinity component with apparent EC(50) values of 1.6 and 62 micrometer. Ratios of receptors in the high- and low-affinity components are 25 and 75%, respectively. Chronic exposure to nicotine or nicotinic antagonists [dihydro-beta-erytroidine (DHbetaE) or methyllycaconitine (MLA)] increases the fraction of high-affinity receptors up to 70%. Upregulated acetylcholine-evoked currents increase by twofold or more and are less sensitive to desensitization. Functional upregulation is independent of protein synthesis as shown by the lack of effect of 20 micrometer cycloheximide. Single-channel currents recorded with 100 nm acetylcholine show predominantly high conductances (38.8 and 43.4 pS), whereas additional smaller conductances (16.7 and 23.5 pS) were observed with 30 micrometer acetylcholine. In addition, long-term exposure to dihydro-beta-erytroidine increases up to three times the frequency of channel openings. These data indicate, in contrast to previous studies, that human alpha4beta2 nAChRs are functionally upregulated by chronic nicotine exposure.
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Affiliation(s)
- B Buisson
- Department of Physiology, Medical Faculty, 1211 Geneva 4, Switzerland
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Abstract
The identification of an equatorial frog toxin, epibatidine, as a potent non-morphinic analgesic, selective for neuronal nicotinic acetylcholine receptors, provoked a marked renewal in our understanding of pain and its mechanisms. In this work we have examined the effects of epibatidine at the major brain rat alpha4beta2 nicotinic acetylcholine receptor expressed in a cell line. Fast drug applications obtained with a modified liquid filament system were used for the analyses of the currents evoked by acetylcholine, nicotine and epibatidine. Characterized by a slow onset and offset, epibatidine responses were of smaller amplitude to those evoked by acetylcholine or nicotine. About a thousand times more sensitive to epibatidine than acetylcholine, the alpha4beta2 receptor also displayed a more pronounced apparent desensitization to this compound. Finally, overnight exposure to 1 nM epibatidine failed to produce the functional upregulation observed with nicotine. These data indicate that, at the rat alpha4beta2 receptor, epibatidine acts as a partial agonist causing a pronounced inhibition of agonist evoked currents at concentrations that do not activate the receptors.
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Affiliation(s)
- B Buisson
- Department of Physiology, Medical Faculty, 1, rue Michel Servet, CH 1211, Geneva, Switzerland
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Abrial D, Blanc A, Réhailia M, Mismetti P, Bouchut C, Laporte-Simitsidis S, Decousus H, Buisson B. A chronopharmacodynamic study on standard heparin, a low molecular weight heparin (nadroparin) and danaproid: establishing and comparing the daily variations of these drugs in rats. Haemostasis 2000; 30:233-42. [PMID: 11251330 DOI: 10.1159/000054139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effects of dosing time on the anticoagulant activity of unfractionated heparin, low molecular weight heparin (nadroparin) and danaproid were investigated. The chronopharmacological comparisons of the drugs were done on the anti-Xa, anti-IIa activities and activated partial thromboplastin time assays. Several dosing times were considered and an analysis based on a population approach was adopted. Under unfractionated heparin, the pharmacological activities did not exhibit significant daily variations. In contrast, significant daily profiles were observed in all the biological assays performed with low molecular weight heparin. Anti-Xa and anti-IIa activities showed some fluctuations over a 24-hour period with a peak at noon. As for the variations of the activated partial thromboplastin time, two peaks were noted early in the morning and at the beginning of nightfall. As for danaproid, only a daytime maximum of anti-Xa activity could be found.
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Affiliation(s)
- D Abrial
- Laboratoire de Biologie Animale et Appliquée, Pavillon 5 Hôpital Bellevue, Saint-Etienne, France.
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Abrial D, Blanc A, Réhailia M, Mismetti P, Bouchut C, Laporte-Simitsidis S, Decousus H, Buisson B. Establishing the dose-dependent daily variations of a low molecular weight heparin (Fraxiparine) through a population approach analysis in the rat. Chronobiol Int 2000; 17:173-85. [PMID: 10757462 DOI: 10.1081/cbi-100101041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The effects of dose and dosing time on the anticoagulant activity of a low molecular weight heparin (Fraxiparine) were studied in rats. Three doses were administered at four evenly spaced dosing times. Rats were kept under a light-dark cycle of 24h, and all the main external factors were constant. The bleeding time, the anti-Xa activity of the drug, and the activated partial thromboplastin time (APTT) were measured. A population approach analysis to assess daily variations was used. With standard methods, interindividual variability may mask potential time-related effects, while the population approach analysis overcomes this difficulty. Bleeding time was at its peak at 04:00 and at its trough at 22:00, suggesting that platelet activity was time of day dependent. For the pharmacological activity of the drug, we compared several pharmacokinetic models derived from a monocompartmental model. The model that describes the anti-Xa pharmacological activity best is expressed through parameters that depend on animal weight and drug level. The model for APTT is of a sinusoidal type for which the clearance depends on the dosing time. The most inter esting result is that the amplitude of this daily variation is linearly dependent on drug level.
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Affiliation(s)
- D Abrial
- Laboratoire de Biologie Animale et Appliquée, Saint-Etienne, France
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Abstract
The structure-function relationship of the neuronal nicotinic acetylcholine receptor is examined in the light of the allosteric concepts. Effects of site-directed mutagenesis as well as those caused by allosteric effector of the physiological and pharmacological receptor properties are discussed.
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Affiliation(s)
- B Buisson
- Department of Physiology, Medical Faculty, Geneva, Switzerland
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Abstract
To extend our knowledge of the pharmacological profile of human alpha4beta2 neuronal nicotinic receptors, we investigated the action of hexamethonium on the major brain human nicotinic acetylcholine receptor (nAChR) stably expressed in human embryonic kidney 293 cells. This compound displays all of the characteristics of an open-channel blocker at the human alpha4beta2 nAChR: a voltage-dependent inhibition (more pronounced at hyperpolarized potentials), absence of competition, and use dependence. Moreover, we observed that classic N-methyl-D-aspartate open-channel blockers amantadine, 3,5-dimethyl-1-adamantanamine (memantine), and dizocilpine [(+)-MK-801] and the calcium channel antagonist 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate are powerful inhibitors of the human alpha4beta2 nAChR. Dose-inhibition curves yield, at -100 mV, IC50 values in the micromolar range for all of compounds and Hill coefficients below unity. Whole-cell current-voltage relationships display a strong rectification profile at hyperpolarized potentials, and current blockades are fitted adequately by a mathematical model that describes the mechanism of an ion channel block. We conclude that these molecules are powerful human alpha4beta2 open-channel blockers ranking in the following order of potency: amantadine > memantine = hexamethonium > 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate approximately (+)-MK-801.
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Affiliation(s)
- B Buisson
- Department of Physiology, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
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15
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Krause RM, Buisson B, Bertrand S, Corringer PJ, Galzi JL, Changeux JP, Bertrand D. Ivermectin: a positive allosteric effector of the alpha7 neuronal nicotinic acetylcholine receptor. Mol Pharmacol 1998; 53:283-94. [PMID: 9463487 DOI: 10.1124/mol.53.2.283] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We report that preapplication of ivermectin, in the micromolar range, strongly enhances the subsequent acetylcholine-evoked current of the neuronal chick or human alpha7 nicotinic acetylcholine receptors reconstituted in Xenopus laevis oocytes and K-28 cells. This potentiation does not result from nonspecific Cl- currents. The concomitant increase in apparent affinity and cooperativity of the dose-response curve suggest that ivermectin acts as a positive allosteric effector. This interpretation is supported by the observation of an increase in efficiency of a partial agonist associated with the potentiation and by the differential effect of ivermectin on mutants within the M2 channel domain. Ivermectin effects reveal a novel allosteric site for pharmacological agents on neuronal alpha7 nicotinic acetylcholine receptors.
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Affiliation(s)
- R M Krause
- Department of Physiology, University Medical Center, 1211 Geneva 4, Switzerland
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Bertrand S, Devillers-Thiéry A, Palma E, Buisson B, Edelstein SJ, Corringer PJ, Changeux JP, Bertrand D. Paradoxical allosteric effects of competitive inhibitors on neuronal alpha7 nicotinic receptor mutants. Neuroreport 1997; 8:3591-6. [PMID: 9427332 DOI: 10.1097/00001756-199711100-00034] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mutation of the conserved leucine residue, in the second transmembrane domain of the neuronal alpha7 acetylcholine receptor to a threonine (L247T) causes pleiotropic alterations of receptor properties. In this study we examined the effects of competitive inhibitors on the alpha7-L247T physiological responses. While the alpha7 competitive inhibitor dihydro-beta-erythroidine evoked a current comparable to that induced by ACh, other inhibitors such as methyllycaconitine (MLA) and alpha-bungarotoxin (alpha-Bgt) caused a blockade of alpha7-L247T to ACh activation. When applied in the absence of ACh, MLA or alpha-Bgt reduced the cell leakage current, showing that alpha7-L247T displays a significant fraction (10%) of spontaneously open channels. These data can be interpreted in terms of an allosteric model, assuming that the L247T mutant possesses a low isomerization constant L and that MLA and alpha-Bgt stabilize the closed, resting state.
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Affiliation(s)
- S Bertrand
- Department of Physiology, Medical Faculty, CMU, Geneva, Switzerland
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Giraudet H, Berthon JL, Buisson B. [Comparison of daily alkaline phosphatase activity of a cyanobacterium (Microcystis aeruginosa) and a diatom (Synedra capitata)]. C R Acad Sci III 1997; 320:451-8. [PMID: 9247024 DOI: 10.1016/s0764-4469(97)81972-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Alkaline phosphatase activity (ALP) (EC: 3.1.3.1) presents a nycthemeral variation in both Microcystis aeruginosa (cyanobacterium) and Synedra capitata (diatom) species. Nevertheless, a comparative study reveals differences between the enzymatic behaviour of these two species. ALP is 33 times higher in cyanobacteria than in diatoms under similar experimental conditions. Microcystis aeruginosa presents therefore a larger capacity for mineralizing organic phosphorus per unit of biomass. Under LD (16:8) conditions, diatoms show a higher enzymatic activity during the day time (around 0.12 mumol pNPP/mn/mg); on the contrary, cyanobacterial enzymatic activity is rather low during the day time and rises at the beginning of night time (around 3.5 mumol pNPP/mn/mg). Finally, the mean of ALP of Synedra capitata is maximal (around 0.12 mumol pNPP/mn/mg) under total darkness (DD) while the mean of enzymatic activity is maximal (around 3.58 mumol pNPP/mn/mg) under permanent light (LL) for the cyanobacteria. These observed differences in the alkaline phosphatase activity between Microcystis aeruginosa and Synedra capitata might, to some extent, explain the observed alternances within the planktonic settlements between algae and cyanobacteria in hypereutrophic lakes such as the Grangent reservoir (Loire).
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Affiliation(s)
- H Giraudet
- Laboratoire de biologie animale et appliquée, faculté des sciences et techniques, université Jean-Monnet, Saint-Etienne France
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Attia J, Blanc A, Hassnaoui M, Rehailia M, Buisson B. Spatial Distribution of a Population of SnailsHelix aspersa maxima(Mollusc, Gastropoda) in Outdoor Rearing Parks. Journal of Applied Animal Research 1997. [DOI: 10.1080/09712119.1997.9706161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Bertrand D, Buisson B, Krause RM, Hu HY, Bertrand S. Electrophysiology: a method to investigate the functional properties of ligand-gated channels. J Recept Signal Transduct Res 1997; 17:227-42. [PMID: 9029493 DOI: 10.3109/10799899709036606] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ligand-gated channels (LGCs) play a fundamental role in the fast transmission of electrical activity from neuron to neuron and/or to effector cells. Studies of LGCs in isolation have become possible since the identification of genes coding for these membrane proteins together with the establishment of reconstitution techniques in host systems. Methods for electrophysiological investigations of LGCs reconstituted either in the Xenopus oocytes or stably tranfected in cell lines are discussed. Functional studies of reconstituted receptors enable fast determination of LGCs' pharmacological profiles and comparison of their physiological properties. Combination of molecular engineering with physiological measurements allows studies with unpreceeding resolution and it is now possible to examine at the amino-acid level the contribution of some residues in the formation of the ligand-binding site or the ionic channel domains.
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MESH Headings
- Acetylcholine/metabolism
- Alkaloids/metabolism
- Animals
- Azocines
- Binding, Competitive
- Curare/metabolism
- Dihydro-beta-Erythroidine/metabolism
- Electrophysiology
- Female
- Humans
- Ion Channel Gating/genetics
- Ion Channel Gating/physiology
- Ion Channels/genetics
- Ion Channels/physiology
- Oocytes/metabolism
- Quinolizines
- Receptors, Cholinergic/genetics
- Receptors, Cholinergic/physiology
- Receptors, GABA-A/genetics
- Receptors, GABA-A/physiology
- Receptors, Glutamate/genetics
- Receptors, Glutamate/physiology
- Receptors, Serotonin/genetics
- Receptors, Serotonin/physiology
- Receptors, Serotonin, 5-HT3
- Xenopus laevis
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Affiliation(s)
- D Bertrand
- Department of Physiology, University of Geneva
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Tanaka H, Tomura M, Kondo J, Teranishi Y, Buisson B, Xie FK, Henderson CE. Low-affinity nerve growth factor receptor is associated with motoneuron axonal pathways. Neurosci Res 1997; 27:21-7. [PMID: 9089695 DOI: 10.1016/s0168-0102(96)01128-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The unidentified cell-surface antigen recognized by monoclonal antibody M7412 is distributed along motoneuron axonal outgrowth pathways in chicken embryos. To better characterize its role in motoneuron development, the M7412 antigen was purified from chicken embryos by immunoaffinity chromatography. Its N-terminal amino acid sequence corresponded to that predicted for chicken low-affinity nerve growth factor receptor (LNGFR). Experiments were performed to confirm that LNGFR was indeed the antigen recognized by M7412. First, M7412 bound to recombinant chicken LNGFR expressed in mammalian cells. Second, a rabbit serum raised to the purified antigen showed the same staining pattern in chicken embryos as did M7412. Lastly, a novel method for direct detection of nerve growth factor (NGF) bound to its receptors was used to show that in mixed spinal cord cultures, only neurons that expressed M7412 antigen had low-affinity binding sites for NGF. Furthermore, at the subcellular level, M7412 labeling was co-localized with bound NGF. The M7412 antigen is thus chicken LNGFR, whose role in motoneuron outgrowth pathways is discussed.
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Affiliation(s)
- H Tanaka
- Department of Pharmacology, Gunma University, School of Medicine, Maebashi, Japan.
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21
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Buisson B, Gopalakrishnan M, Arneric SP, Sullivan JP, Bertrand D. Human alpha4beta2 neuronal nicotinic acetylcholine receptor in HEK 293 cells: A patch-clamp study. J Neurosci 1996; 16:7880-91. [PMID: 8987816 PMCID: PMC6579202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The cloning and expression of genes encoding for the human neuronal nicotinic acetylcholine receptors (nAChRs) has opened new possibilities for investigating their physiological and pharmacological properties. Cells (HEK 293) stably transfected with two of the major brain subunits, alpha4 and beta2, were characterized electrophysiologically using the patch-clamp technique. Fast application of the natural ligand ACh can evoke currents up to 3500 pA, with an apparent affinity (EC50) of 3 microM and a Hill coefficient of 1.2. The rank order of potency of four nAChR ligands to activate human alpha4beta2 receptors is (-)-nicotine > ACh > (-)-cytisine > ABT-418. At saturating concentrations, the efficacy of these ligands is ABT-418 >> (-)-nicotine > ACh >> (-)-cytisine > GTS-21 (previously named DMXB). Coapplication of 1 microM ACh with known nAChR inhibitors such as dihydro-beta-erythroidine and methyllycaconitine reversibly reduces the current evoked by the agonist with respective IC50 values of 80 nM and 1.5 microM. The current-voltage relationship of human alpha4beta2 displays a strong rectification at positive potentials. Experiments of ionic substitutions suggest that human alpha4beta2 nAChRs are permeable to sodium and potassium ions. In the "outside-out" configuration, ACh evokes unitary currents (main conductance 46 pS) characterized by a very fast rundown. Potentiation of the ACh-evoked currents is observed when the extracellular calcium concentration is increased from 0.2 to 2 mM. In contrast, however, a reduction of the evoked currents is observed when calcium concentration is elevated above 2 mM.
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Affiliation(s)
- B Buisson
- Department of Physiology, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
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Gopalakrishnan M, Buisson B, Touma E, Giordano T, Campbell JE, Hu IC, Donnelly-Roberts D, Arneric SP, Bertrand D, Sullivan JP. Stable expression and pharmacological properties of the human alpha 7 nicotinic acetylcholine receptor. Eur J Pharmacol 1995; 290:237-46. [PMID: 7589218 DOI: 10.1016/0922-4106(95)00083-6] [Citation(s) in RCA: 143] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The alpha 7 neuronal nicotinic acetylcholine receptor subtype forms a Ca(2+)-permeable homooligomeric ion channel sensitive to alpha-bungarotoxin in Xenopus oocytes. In this study, we have stably and functionally expressed the human alpha 7 cDNA in a mammalian cell line, HEK-293 and examined its pharmacologic properties. [125I] alpha-Bungarotoxin bound to transfected cells with a Kd value of 0.7 nM and a Bmax value of 973 pmoL/mg protein. No specific binding was detected in untransfected cells. Specific binding could be displaced by unlabeled alpha-bungarotoxin (Ki = 0.5 nM) and an excellent correlation was observed between binding affinities of a series of nicotinic cholinergic ligands in transfected cells and those in the human neuroblastoma IMR-32 cell line. Additionally, cell surface expression of alpha 7 receptors was detected by fluorescein isothiocyanate-conjugated alpha-bungarotoxin in transfected cells. Whole cell currents sensitive to blockade by alpha-bungarotoxin, and with fast kinetics of activation and inactivation, were recorded from transfected cells upon rapid application of (-)-nicotine or acetylcholine with EC50 values of 49 microM and 155 microM respectively. We conclude that the human alpha 7 subunit when expressed alone can form functional ion channels and that the stably transfected HEK-293 cell line serves as a unique system for studying human alpha 7 nicotinic receptor function and regulation, and for examining ligand interactions.
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Affiliation(s)
- M Gopalakrishnan
- Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, IL 60064-3500, USA
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Mettling C, Gouin A, Robinson M, el M'Hamdi H, Camu W, Bloch-Gallego E, Buisson B, Tanaka H, Davies AM, Henderson CE. Survival of newly postmitotic motoneurons is transiently independent of exogenous trophic support. J Neurosci 1995; 15:3128-37. [PMID: 7722651 PMCID: PMC6577782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We compared the survival requirements of early- and late-born motoneurons from E5 chicken spinal cord. Density gradient centrifugation followed by immunopanning using SC1 antibody allowed us to purify two size classes of motoneuron. Large motoneurons retained by 6.8% metrizamide were shown by BrdU labeling in ovo to be born on average 1.5 d earlier than the small motoneurons recovered from the metrizamide pellet. Large motoneurons were both biochemically and functionally more mature: they expressed higher levels of choline acetyltransferase and low-affinity neurotrophin receptor, and had an acute requirement for trophic support from muscle-derived factors. After 24 hr in culture in basal medium, all early-born motoneurons died, whereas 60% of late-born motoneurons survived. Small motoneurons can develop into large motoneurons in ovo, suggesting that they represent a general transitional stage in motoneuron development. Our results suggest that a defined period elapses between birth of a motoneuron and its acquisition of trophic dependence, possibly corresponding to the time required for target innervation. This property may have important consequences for the timing and regulation of developmental motoneuron death.
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Affiliation(s)
- C Mettling
- INSERM U.382, Biochimie CNRS-INSERM, Montpellier, France
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Buisson B, Laflamme L, Bottari SP, de Gasparo M, Gallo-Payet N, Payet MD. A G protein is involved in the angiotensin AT2 receptor inhibition of the T-type calcium current in non-differentiated NG108-15 cells. J Biol Chem 1995; 270:1670-4. [PMID: 7829501 DOI: 10.1074/jbc.270.4.1670] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In non-differentiated NG108-15 cells, both angiotensin II (Ang II) (100 nM) and CGP 42112 (100 nM) decreased the T-type calcium current amplitude by 24 +/- 2% and 21 +/- 3%, respectively. cGMP is not a mediator of the Ang II effect, since loading of cells with 50 microM cGMP did not prevent the inhibitory effects of Ang II. The effects of Ang II involves a non-identified GTPase activity since incubation with GDP beta S (3 mM) completely reversed the inhibitory effect of Ang II while GTP gamma S mimicked its effect. However, Ang II binding was not affected by GTP gamma S, and the effect of Ang II was not modified in pertussis toxin-treated cells. The inhibitory effect of Ang II on the T-type Ca2+ current involves a phosphotyrosine phosphatase activity since sodium orthovanadate prevented the effects of Ang II, although microcystin-LR, a selective Ser/Thr phosphatase 1 and 2A inhibitor, did not modify the effect of Ang II. These results provide the first evidence of a modulation of membrane conductance by Ang II through the AT2 receptor and demonstrate the involvement of a phosphotyrosine phosphatase and a G protein in the AT2 transduction mechanism in NG108-15 cells. Moreover, our data suggest that phosphotyrosine phosphatase activation is proximal to receptor occupation, since sodium orthovanadate inhibits both GTPase activity and T-type current blockage induced by Ang II or CGP 42112, while GTP gamma S inhibition of the T-type calcium current is not impaired.
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Affiliation(s)
- B Buisson
- Service of Endocrinology, Faculty of Medicine, University of Sherbrooke, Québec, Canada
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Puchacz E, Buisson B, Bertrand D, Lukas RJ. Functional expression of nicotinic acetylcholine receptors containing rat alpha 7 subunits in human SH-SY5Y neuroblastoma cells. FEBS Lett 1994; 354:155-9. [PMID: 7957916 DOI: 10.1016/0014-5793(94)01108-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Neuronal nicotinic acetylcholine receptors (nAChR) are made from different combinations of subunits encoded by a diverse family of genes. However, the recently cloned alpha 7 gene codes for subunits that can form homooligomeric nAChR complexes when expressed in Xenopus oocytes. Electrophysiological studies reveal that these alpha 7-nAChR function as alpha-bungarotoxin (Bgt)-sensitive, quickly activating/inactivating ion channels with a unique pharmacological profile and an unusually high permeability to calcium ions. Although similar observations have been made in studies of Bgt-sensitive, functional nAChR subtypes that are naturally expressed in neuronal cells, all attempts until now to reconstitute functional alpha 7-nAChR in cell lines have failed. Here we report the successful use of SH-SY5Y human neuroblastoma cells, which naturally express low levels of endogenous alpha 7 transcripts, to stably overexpress heterologous rat nAChR alpha 7 transgenes. These transgenes are expressed as the appropriately-sized alpha 7 messages and protein, and stably transfected SH-SY5Y cells have over 30-times higher levels of specific Bgt binding sites than do wild-type cells. Whole cell current recordings confirm that transfected cells express functional nAChR that are sensitive to blockade by Bgt and display the typical physiological and pharmacological profiles of alpha 7-nAChR. We conclude that stable, functional expression of alpha 7 transgenes in a mammalian cell line has been achieved for the first time.
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Affiliation(s)
- E Puchacz
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, AZ 85013
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Buisson B, Bottari SP, de Gasparo M, Gallo-Payet N, Payet MD. The angiotensin AT2 receptor modulates T-type calcium current in non-differentiated NG108-15 cells. FEBS Lett 1992; 309:161-4. [PMID: 1324194 DOI: 10.1016/0014-5793(92)81086-2] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We report here that angiotensin II (AII) and the AT2 receptor-selective ligand, CGP 42112, modulate the T-type calcium current in non-differentiated NG108-15 cells, which express only AT2 receptors. Both peptides decrease the T-type calcium current at membrane potentials above -40 mV and shift the current-voltage curve at lower potentials with maximal effect between 5 and 10 min after application. These data describe a new cellular response to AII and suggest that the AT2 receptor mediates certain neurophysiological actions of this hormone.
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Affiliation(s)
- B Buisson
- Service of Endocrinology, Faculty of Medicine, University of Sherbrooke, Qué., Canada
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Borja M, Perez E, Pupier R, Buisson B. Entrainment of the circadian activity rhythm in the juvenile trout,Salmo truttaL., by red light. ACTA ACUST UNITED AC 1990. [DOI: 10.1080/09291019009360029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Benneton M, Rougny R, Vico L, Buisson B. [A simple device, using a microprocessor, to record the circadian locomotor activity of animals]. Med Biol Eng Comput 1984; 22:382-4. [PMID: 6748778 DOI: 10.1007/bf02442113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Buisson B. [Rhythmic behavior of an isolated polyp of a colony of Veretillum cynomorium Pall. (Cnidaria Pennatularia)]. C R Acad Hebd Seances Acad Sci D 1973; 277:1541-4. [PMID: 4149726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Wautier J, Pavans de Ceccatty M, Richardot M, Buisson B, Hernandez ML. Les étapes de la croissance chez Gundlachia sp.(Mollusque, Ancylidae). ACTA ACUST UNITED AC 1962. [DOI: 10.3406/linly.1962.7031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Wautier J, Pavans de Ceccatty M, Hernandez ML, Richardot M, Buisson B. Histo-physiologie des corrélations neuro-hormonales lors du cycle sexuel de Gundlachia. ACTA ACUST UNITED AC 1962. [DOI: 10.3406/linly.1962.7033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Wautier J, Pavans de Ceccatty M, Richardot M, Buisson B, Hernandez ML. Notes sur les complexes neuro-endocriniens de Gundlachia sp. (Mollusque Ancylidae). ACTA ACUST UNITED AC 1961. [DOI: 10.3406/linly.1961.6948] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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