科研之友
微信
新浪微博
Facebook
分享链接
摘要
Heteropentameric nicotinic acetylcholine receptors (nAChR) mediate fast synaptic transmission in ganglia of the autonomic nervous system. It is undisputed that alpha 3 and beta 4 are the predominant subunits in the superior cervical ganglion (SCG); however, reports on the presence of receptors that contain alpha 4 have been controversial. Here, we have searched for the presence of alpha 4-containing nAChRs in the postnatal rat and mouse SCG. We now show by immunoprecipitation combined with radioligand binding that alpha 4-containing receptors constitute about 20% of hetero-oligomeric nAChRs in postnatal Day 3 (P3) mice. However, already by P9, the level of alpha 4 approaches zero. In contrast, the number of alpha 4-containing receptors is close to zero in the rat SCG at all times investigated. Deletion of the beta 2 subunit by using alpha 5 beta 2-double knockout (KO) mice removes all alpha 4-containing receptors, suggesting that in the postnatal mouse SCG, alpha 4 co-assembles only with beta 2 but not with b4. alpha 4 beta 2 receptors are, on the other hand, up-regulated in the SCG of P3 alpha 5 beta 4-double KO mice, where they make up about 50% of receptors that bind [H-3]-epibatidine. Nonetheless, receptors on the surface of SCG neurons from alpha 5 beta 4-double KO mice maintained for one to two days in culture comprise < 10% of alpha 4 beta 2 and > 90% of alpha 3 beta 2, as determined by patch clamp recordings with alpha 4 beta 2- and alpha 3 beta 2-specific ligands. We propose that in the P3 SCG of wild type mice, alpha 3 beta 4 (+/-alpha 5) represent about 62% of receptors, whereas 17% are alpha 3 beta 2 beta 4, and 21% are alpha 4 beta 2 (+/-alpha 5) receptors.
- 出版日期2011-5
