Neuronal nicotinic acetylcholine receptors (nAChRs) are Ca2+-permeable ligand-gated channels widely expressed in the central and peripheral nervous system. One of the most Ca2+ selective isoform is the homopentameric α7-nAChR implicated in schizophrenia. The activity of α7-nAChRs is usually recorded electrophysiologically, which limits the amount of information obtained. Here, we used fluorescence imaging to record Ca2+ transients associated with activation of the α7-nAChR in neuroblastoma cells stably expressing human α7-nAChRs. Application of nicotine (50 μM) consistently evoked transient (30 s), stereotyped Ca2+ responses that were inhibited by the selective α7-nAChRs antagonists methyllycaconitine (MLA) and α-bungarotoxin, and greatly increased and prolonged by the allosteric modulator PNU-120596 (1μM). Unexpectedly, brief (1–5 s), repetitive Ca2+ transients of sub-micrometric dimension were observed in filopodia of cells expressing α7-nAChR. PNU-120596 increased the frequency and slowed the decay kinetics of these miniature Ca2+ elevations, which were insensitive to ryanodine, preserved during hyperpolarisation, and prevented by MLA, α-bungarotoxin, or Ca2+ removal. Global Ca2+ 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 Ca2+ signals generated by α7-nAChRs can be recorded optically both in cell lines and in intact tissues. The possibility to image miniature Ca2+ signals enables to map the location of functional α7-nAChR channel clusters within cells and to analyze their single channel properties optically. Deciphering the rich pattern of intracellular Ca2+ signals generated by the activity of the α7-nAChRs will reveal the physiological role of these receptor-channels.

Gilbert, D., Lecchi, M., Arnaudeau, S., Bertrand, D., Demaurex, N. (2008). Local and global calcium signals associated with the opening of neuronal alpha7 nicotinic acetylcholine receptors. CELL CALCIUM, 45(2), 198-207 [10.1016/j.ceca.2008.10.003].

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

LECCHI, MARZIA MARIA;
2008

Abstract

Neuronal nicotinic acetylcholine receptors (nAChRs) are Ca2+-permeable ligand-gated channels widely expressed in the central and peripheral nervous system. One of the most Ca2+ selective isoform is the homopentameric α7-nAChR implicated in schizophrenia. The activity of α7-nAChRs is usually recorded electrophysiologically, which limits the amount of information obtained. Here, we used fluorescence imaging to record Ca2+ transients associated with activation of the α7-nAChR in neuroblastoma cells stably expressing human α7-nAChRs. Application of nicotine (50 μM) consistently evoked transient (30 s), stereotyped Ca2+ responses that were inhibited by the selective α7-nAChRs antagonists methyllycaconitine (MLA) and α-bungarotoxin, and greatly increased and prolonged by the allosteric modulator PNU-120596 (1μM). Unexpectedly, brief (1–5 s), repetitive Ca2+ transients of sub-micrometric dimension were observed in filopodia of cells expressing α7-nAChR. PNU-120596 increased the frequency and slowed the decay kinetics of these miniature Ca2+ elevations, which were insensitive to ryanodine, preserved during hyperpolarisation, and prevented by MLA, α-bungarotoxin, or Ca2+ removal. Global Ca2+ 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 Ca2+ signals generated by α7-nAChRs can be recorded optically both in cell lines and in intact tissues. The possibility to image miniature Ca2+ signals enables to map the location of functional α7-nAChR channel clusters within cells and to analyze their single channel properties optically. Deciphering the rich pattern of intracellular Ca2+ signals generated by the activity of the α7-nAChRs will reveal the physiological role of these receptor-channels.
Articolo in rivista - Articolo scientifico
calcium, nicotine, confocal microscopy, optical single-channel recordings, calcium microdomains
English
198
207
Gilbert, D., Lecchi, M., Arnaudeau, S., Bertrand, D., Demaurex, N. (2008). Local and global calcium signals associated with the opening of neuronal alpha7 nicotinic acetylcholine receptors. CELL CALCIUM, 45(2), 198-207 [10.1016/j.ceca.2008.10.003].
Gilbert, D; Lecchi, M; Arnaudeau, S; Bertrand, D; Demaurex, N
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/6666
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