Biochemical and functional properties of distinct nicotinic acetylcholine receptors in the superior cervical ganglion of mice with targeted deletions of nAChR subunit genes.
Nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic transmission in ganglia of the autonomic nervous system. Here, we determined the subunit composition of hetero-pentameric nAChRs in the mouse superior cervical ganglion (SCG), the function of distinct receptors (obtained by deletions of nAChR subunit genes) and mechanisms at the level of nAChRs that might compensate for the loss of subunits. As shown by immunoprecipitation and Western blots, wild-type (WT) mice expressed: alpha 3 beta 4 (55%), alpha 3 beta 4 alpha 5 (24%) and alpha 3 beta 4 beta 2 (21%) nAChRs. nAChRs in beta 4 knockout (KO) mice were reduced to < 15% of controls and no longer contained the alpha 5 subunit. Compound action potentials, recorded from the postganglionic (internal carotid) nerve and induced by preganglionic nerve stimulation, did not differ between alpha 5 beta 4 KO and WT mice, suggesting that the reduced number of receptors in the KO mice did not impair transganglionic transmission. Deletions of alpha 5 or beta2 did not affect the overall number of receptors and we found no evidence that the two subunits substitute for each other. In addition, dual KOs allowed us to study the functional properties of distinct alpha 3 beta4 and alpha 3 beta 2 receptors that have previously only been investigated in heterologous expression systems. The two receptors strikingly differed in the decay of macroscopic currents, the efficacy of cytisine, and their responses to the alpha-conotoxins AuIB and MII. Our data, based on biochemical and functional experiments and several mouse KO models, clarify and significantly extend previous observations on the function of nAChRs in heterologous systems and the SCG.
David
Reinhard
R
Department of Biochemistry and Molecular Biology, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Ciuraszkiewicz
Anna
A
Simeone
Xenia
X
Orr-Urtreger
Avi
A
Papke
Roger L
RL
McIntosh
J M
JM
Huck
Sigismund
S
Scholze
Petra
P
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000493:pharmacokinetics; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D018678:Cholinergic Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D007555:Isoxazoles / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018722:Nicotinic Agonists / Q000493:pharmacokinetics; D009865:Oocytes; D018408:Patch-Clamp Techniques; D010671:Phenylurea Compounds / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics*; D011725:Pyridines / Q000493:pharmacokinetics; D011978:Receptors, Nicotinic / Q000145:classification* / Q000172:deficiency*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D018709:Statistics, Nonparametric; D017783:Superior Cervical Ganglion / Q000166:cytology*; D013779:Tetrodotoxin / Q000494:pharmacology; D014316:Tritium / Q000493:pharmacokinetics; D014981:Xenopus
C508388:1-(5-chloro-2,4-dimethoxyphenyl)-3-(5-methylisoxazol-3-yl)urea; D019086:Bridged Bicyclo Compounds, Heterocyclic; D018678:Cholinergic Agents; D007555:Isoxazoles; D018722:Nicotinic Agonists; D010671:Phenylurea Compounds; D021122:Protein Subunits; D011725:Pyridines; D011978:Receptors, Nicotinic; D026941:Sodium Channel Blockers; D014316:Tritium; D013779:Tetrodotoxin; C082748:epibatidine