Distribution of neuronal nicotinic acetylcholine receptors containing different alpha-subunits in the submucosal plexus of the guinea-pig.
The subunit composition and localisation of nicotinic acetylcholine receptors (nAChRs) in the submucosal plexus of the guinea-pig ileum were studied using both affinity-purified monoclonal and polyclonal antibodies against alpha3, alpha4, alpha5 and alpha7 nAChR subunits and specific alpha7-containing nAChRs blocker methyllycaconitine (MLA). By means of immunohistochemistry performed in non-dissociated preparations, it was found that only 4% of submucosal ganglia expressed nAChRs. Specific staining, associated with cell membranes, was found with alpha3-, alpha5- and alpha7-, but not alpha4-specific antibodies. Double staining using alpha5- and alpha7-specific antibodies demonstrated that about one-half of the nAChR-positive ganglia contained neurons immunoreactive to both antibodies, while the others possessed either alpha5- or alpha7-immunoreactivity. Nanomolar concentrations of MLA prevented alpha7-specific antibody binding and did not influence the alpha5-specific antibody binding even when applied in micromolar concentrations. In electrophysiological experiments performed using a patch-clamp 'whole-cell' recording method, the neurons were identified by their sensitivity to MLA. In conclusion, submucosal neurons of the guinea-pig ileum express nAChRs containing alpha3-, alpha5- and alpha7-subunits. The co localisation of alpha5- and alpha7-subunits found in immunohistochemical experiments as well as kinetic characteristics of MLA-blocked receptors found by electrophysiological experiments allow us to suggest the presence of heteromeric alpha7-containing nAChRs in the submucosal plexus of the guinea-pig ileum.
Glushakov
Alexander V
AV
Department of Anesthesiology, College of Medicine, University of Florida, PO Box 100254, Gainesville, FL 32610-0254, USA.
Voytenko
Larysa P
LP
Skok
Marina V
MV
Skok
Vladimir
V
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005725:Ganglia, Autonomic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation* / Q000502:physiology; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D021122:Protein Subunits / Q000037:antagonists & inhibitors / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D013368:Submucous Plexus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D064569:alpha7 Nicotinic Acetylcholine Receptor
D018733:Nicotinic Antagonists; D021122:Protein Subunits; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor