α4β2 nicotinic acetylcholine receptors in the early postnatal mouse superior cervical ganglion.
DEVELOPMENTAL NEUROBIOLOGY(2011)
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. (C) 2011 Wiley Periodicals, Inc. Develop Neurobiol 71: 390-399, 2011
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关键词
acetylcholine receptor [AChR],subunit composition,immunoprecipitation,knockout,patch clamp
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