Dystrophin stabilizes ?3- but not ?7-containing nicotinic acetylcholine receptor subtypes at the postsynaptic apparatus in the mouse superior cervical ganglion

The nicotinic acetylcholine receptor (nAChR) subtypes were characterized in the superior cervical ganglion (SCG) of wild-type and dystrophin-lacking mdx mice. The binding of Epibatidine and ?Bungarotoxin, ligands for ?3- and ?7-containing receptors, respectively, revealed, for each ligand, a single class of high-affinity binding sites, with similar affinity in both wild-type and mdx mice. The Epibatidine-labeled receptors were immunoprecipitated by antibodies against the ?3, ?2, and ?4 subunits. Immunocytochemistry showed that the percentage of ?3-, ?2-, and ?4- but not of ?7-immunopositive postsynaptic specializations was significantly lower in mdx than in wild-type mouse SCG. These observations suggest that the mouse SCG contains nAChRs, stabilized by dystrophin, in which the ?3 subunit is associated with the ?2 and/or ?4 subunits. Conversely, dystrophin is not involved in the stabilization of the ?7-containing nAChRs, as the percentage of ?7-immunopositive synapses is similar in both wild-type and mdx mouse SCG. © 2002 Elsevier Science (USA).