U18666A A Cholesterol-Inhibition Agent Modulates Human Neuronal Nicotinic Acetylcholine Receptors Heterologously Expressed In Sh-Ep1 Cell Line
In this study, we evaluate the effects of (3Î²)-3-[2-(diethylamino) ethoxy]androst-5-en-17-one dihydrochloride (U18666A), a cholesterol synthesis/transporter inhibitor, on selected human neuronal nicotinic acetylcholine receptors (nAChRs) heterologously expressed in the SH-EP1 cell line using whole-cell patch-clamp recordings. The results indicate that with 2-min pretreatment, U18666A inhibited different nAChR subtypes with a rank-order of potency (IC50 of whole-cell peak current): Î±4Î²2 (8.0 Â± 3.0 nM) > Î±3Î²2 (1.7 Â± 0.4 Î¼M) > Î±4Î²4 (26 Â± 7.2 Î¼M) > Î±7 (> 100 Î¼M), suggesting this compound is more selective to Î±4Î²2-nAChRs. Thus, the pharmacological profiles and mechanisms of U18666A acting on Î±4Î²2-nAChRs were investigated in detail. U18666A suppresses both peak and steady state components of whole-cell currents mediated by human Î±4Î²2-nAChRs in response to nicotine. In nicotine-induced concentration-response curves, U18666A reduces nicotine-induced current at maximally effective agonist concentrations without influencing nicotine's EC50 value, suggesting a non-competitive inhibition. U18666A-induced inhibition of nAChR function is concentration-, voltage-, and use-dependent, suggesting an open channel block. Taken into consideration of âˆ¼10 000-fold enhancement of the potency of U18666A after 2-min pre-treatment, this compound also likely inhibits Î±4Î²2-nAChRs through a close channel block. In addition, the U18666A-induced inhibition in Î±4Î²2-nAChRs is not mediated by either increased receptor endocytosis or altered cell cholesterol. These data indicate that U18666A is a potent antagonist of Î±4Î²2- nAChRs and may be useful as a tool in the functional characterization and pharmacological profiling of nAChRs, as well as a potential candidate for smoking cessation. Â© 2009 International Society for Neurochemistry.
Journal of Neurochemistry
Digital Object Identifier (DOI)
Zheng, Chao; Wang, Meng Ya; Liu, Qiang; Wakui, Makoto; Whiteaker, Paul; Lukas, Ronald J.; and Wu, Jie, "U18666A A Cholesterol-Inhibition Agent Modulates Human Neuronal Nicotinic Acetylcholine Receptors Heterologously Expressed In Sh-Ep1 Cell Line" (2009). Neurobiology. 396.