Pharmacological And Functional Comparisons Of Î±6/Î±3Î²2Î²3-Nachrs And Î±4Î²2-Nachrs Heterologously Expressed In The Human Epithelial Sh-Ep1 Cell Line
Neuronal nicotinic acetylcholine receptors containing Î±6 subunits (Î±6 * -nAChRs) show highly restricted distribution in midbrain neurons associated with pleasure, reward, and mood control, suggesting an important impact of Î±6 * -nAChRs in modulating mesolimbic functions. However, the function and pharmacology of Î±6 * -nAChRs remain poorly understood because of the lack of selective agonists for Î±6 * -nAChRs and the challenging heterologous expression of functional Î±6 * -nAChRs in mammalian cell lines. In particular, the Î±6 subunit is commonly co-expressed with Î±4 * -nAChRs in the midbrain, which masks Î±6 * -nAChR (without Î±4) function and pharmacology. In this study, we systematically profiled the pharmacology and function of Î±6 * -nAChRs and compared these properties with those of Î±4Î²2 nAChRs expressed in the same cell line. Heterologously expressed human Î±6/Î±3 chimeric subunits (Î±6 N-terminal domain joined with Î±3 trans-membrane domains and intracellular loops) with Î²2 and Î²3 subunits in the human SH-EP1 cell line (Î±6 * -nAChRs) were used. Patch-clamp whole-cell recordings were performed to measure these receptor-mediated currents. Functionally, the heterologously expressed Î±6 * -nAChRs exhibited excellent function and showed distinct nicotine-induced current responses, such as kinetics, inward rectification and recovery from desensitization, compared with Î±4Î²2-nAChRs. Pharmacologically, Î±6 * -nAChR was highly sensitive to the Î±6 subunit-selective antagonist Î±-conotoxin MII but had lower sensitivity to mecamylamine and dihydro-Î²-erythroidine. Nicotine and acetylcholine were found to be full agonists for Î±6 * -nAChRs, whereas epibatidine and cytisine were determined to be partial agonists. Heterologously expressed Î±6 * -nAChRs exhibited pharmacology and function distinct from those of Î±4Î²2-nAChRs, suggesting that Î±6 * -nAChRs may mediate different cholinergic signals. Our Î±6 * -nAChR expression system can be used as an excellent cell model for future investigations of Î±6 * -nAChR function and pharmacology.
Acta Pharmacologica Sinica
Digital Object Identifier (DOI)
Chen, De jie; Gao, Fen fei; Ma, Xiao Kuang; Shi, Gang gang; Huang, Yuan bing; Su, Quang xi; Sudweeks, Sterling; Gao, Ming; Dharshaun, Turner; Eaton, Jason Brek; Chang, Yong; Mcintosh, J. Michael; Lukas, Ronald J.; Whiteaker, Paul; Steffensen, Scott C.; and Wu, Jie, "Pharmacological And Functional Comparisons Of Î±6/Î±3Î²2Î²3-Nachrs And Î±4Î²2-Nachrs Heterologously Expressed In The Human Epithelial Sh-Ep1 Cell Line" (2018). Neurobiology. 63.