Cholinergic signal transduction in the mouse sphenopalatine ganglion.
The sphenopalatine ganglia (SPG) receive their preganglionic innervation from the ventro-lateral reticular formation and nuclei of the caudal pons, and are involved in parasympathetic control of cranial glandular and vascular components including the blood supply to specific brain areas. In 53% of all SPG neurons, a particular member (MOL2.3) of the odorant receptor superfamily is co-expressed with green fluorescent protein (GFP) in MOL2.3 transgenic mouse pups. Choline acetyltransferase and vesicular acetylcholine transporter (VAChT) could be demonstrated in 90% of the GFP-positive, and 60% of the GFP-negative cells, these cells thus representing cholinergic neurons. Some 50% of all SPG neurons were nitrergic at a high rate of VAChT co-expression, the majority of them being GFP-positive. Most SPG neurons received cholinergic innervation as demonstrated by perineuronal VAChT immunoreactive nerve terminals. To characterize cholinergic signal transduction in SPG neurons, calcium imaging experiments were performed in a SPG primary culture system containing GFP-positive and -negative neurons. Ganglionic neurons could repeatedly be activated by cholinergic stimulation in a dose-dependent manner, with calcium entering all cells from the extracellular compartment. Stimulation with specific agonists supported prevalence of nicotinic cholinergic receptors (nAChRs). Inhibition of cholinergically induced intracellular calcium signalling by various omega-conotoxins indicated functional expression of alpha 3 beta 4 and alpha 7 nAChR subtypes in murine SPG cells, which could be supported by RT-PCR analysis of the neonatal mouse SPG. With regard to secondary cholinergic activation, L- but not N-subtype voltage-gated calcium channels might represent a prime target. Nicotinic signal transduction did not prove to be different in GFP-positive as compared to-negative murine SPG neurons.
Rafalzik
Sandra
S
Department of Veterinary Physiology, Justus-Liebig-University Giessen, Frankfurter Strasse 100, D-35392 Giessen, Germany.
Pehl
Ulrich
U
Ott
Daniela
D
Strotmann
Jörg
J
Wolff
Miriam
M
Gerstberger
Rüdiger
R
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D015220:Calcium Channels / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D002799:Cholinergic Fibers / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018722:Nicotinic Agonists / Q000494:pharmacology; D026602:Nitrergic Neurons / Q000166:cytology / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D018035:Receptors, Odorant / Q000235:genetics; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D050494:Vesicular Acetylcholine Transport Proteins / Q000378:metabolism; D064569:alpha7 Nicotinic Acetylcholine Receptor; D020960:omega-Conotoxins / Q000494:pharmacology
D015220:Calcium Channels; C579166:Chrna7 protein, mouse; C453199:MOL2.3 protein, mouse; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D018035:Receptors, Odorant; C493460:Slc18a3 protein, mouse; D050494:Vesicular Acetylcholine Transport Proteins; D064569:alpha7 Nicotinic Acetylcholine Receptor; C403530:nicotinic receptor alpha3beta4; D020960:omega-Conotoxins; D049452:Green Fluorescent Proteins; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine