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

Abstract

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 alphaBungarotoxin, ligands for alpha3- and alpha7-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 alpha3, beta2, and beta4 subunits. Immunocytochemistry showed that the percentage of alpha3-, beta2-, and beta4- but not of alpha7-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 alpha3 subunit is associated with the beta2 and/or beta4 subunits. Conversely, dystrophin is not involved in the stabilization of the alpha7-containing nAChRs, as the percentage of alpha7-immunopositive synapses is similar in both wild-type and mdx mouse SCG.