Local and global calcium signals associated with the opening of neuronal alpha7 nicotinic acetylcholine receptors

Article Article scientifique Article Local and global calcium signals associated with the opening of neuronal alpha7 nicotinic acetylcholine receptors eng 2009 author Gilbert Dorothée 649522 author Lecchi Marzia Maria 547128 author Arnaudeau Serge 508253 author Bertrand Daniel 24727 author Demaurex Nicolas 0000-0002-9933-6772 24642 198-207 10.1016/j.ceca.2008.10.003 19038445 0143-4160 http://pdn.sciencedirect.com/science?_ob=MiamiImageURL&_cid=272490&_user=9565874&_pii=S0143416008001528&_check=y&_origin=article&_zone=toolbar&_coverDate=28-Feb-2009&view=c&originContentFamily=serial&wchp=dGLbVlV-zSkWA&md5=759803738e6cc308a0898e9383dd5a7f/1-s2.0-S0143416008001528-main.pdf Neuronal nicotinic acetylcholine receptors (nAChRs) are Ca(2+)-permeable ligand-gated channels widely expressed in the central and peripheral nervous system. One of the most Ca(2+) selective isoform is the homopentameric alpha7-nAChR implicated in schizophrenia. The activity of alpha7-nAChRs is usually recorded electrophysiologically, which limits the amount of information obtained. Here, we used fluorescence imaging to record Ca(2+) transients associated with activation of the alpha7-nAChR in neuroblastoma cells stably expressing human alpha7-nAChRs. Application of nicotine (50 microM) consistently evoked transient (30s), stereotyped Ca(2+) responses that were inhibited by the selective alpha7-nAChRs antagonists methyllycaconitine (MLA) and alpha-bungarotoxin, and greatly increased and prolonged by the allosteric modulator PNU-120596 (1 microM). Unexpectedly, brief (1-5s), repetitive Ca(2+) transients of sub-micrometric dimension were observed in filopodia of cells expressing alpha7-nAChR. PNU-120596 increased the frequency and slowed the decay kinetics of these miniature Ca(2+) elevations, which were insensitive to ryanodine, preserved during hyperpolarisation, and prevented by MLA, alpha-bungarotoxin, or Ca(2+) removal. Global Ca(2+) responses were also recorded in ganglion cells of embryo chicken retina during co-application of PNU-120596 and nicotine, together with whole-cell currents and brief current bursts. These data demonstrate that Ca(2+) signals generated by alpha7-nAChRs can be recorded optically both in cell lines and in intact tissues. The possibility to image miniature Ca(2+) signals enables to map the location of functional alpha7-nAChR channel clusters within cells and to analyze their single channel properties optically. Deciphering the rich pattern of intracellular Ca(2+) signals generated by the activity of the alpha7-nAChRs will reveal the physiological role of these receptor-channels. Allosteric Regulation/drug effects Animals *Calcium Signaling/drug effects Cell Line, Tumor Chickens Electrophysiological Phenomena/drug effects Humans Isoxazoles/pharmacology Neurons/cytology/drug effects/*metabolism Nicotine/pharmacology Phenylurea Compounds/pharmacology Receptors, Nicotinic/*metabolism Retinal Ganglion Cells/cytology/drug effects/metabolism Dewey 612 134 Département de physiologie cellulaire et métabolisme 21C false 168 Signaux intracellulaires 210 Cell calcium 45 2 b26a81ac-3713-46d6-9fd3-89faba8c23cb Article Restricted file1.pdf 1241626 application/pdf restrictedAccess Faculté de médecine / Section de médecine fondamentale / Département de physiologie cellulaire et métabolisme

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Local and global calcium signals associated with the opening of neuronal alpha7 nicotinic acetylcholine receptors	Cell calcium			2009	621	0

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Gilbert, Dorothée