Cocaine Potently Blocks Neuronal Î±3Î²4 Nicotinic Acetylcholine Receptors In Sh-Sy5Y Cells
Cocaine is one of the most abused illicit drugs worldwide. It is well known that the dopamine (DA) transporter is its major target; but cocaine also acts on other targets including nicotinic acetylcholine receptors (nAChRs). In this study, we investigated the effects of cocaine on a special subtype of neuronal nAChR, Î±3Î²4-nAChR expressed in native SH-SY5Y cells. Î±3Î²4-nAChR-mediated currents were recorded using whole-cell recordings. Drugs were applied using a computer-controlled U-tube drug perfusion system. We showed that bath application of nicotine induced inward currents in a concentration-dependent manner with an EC50 value of 20 ÂµM. Pre-treatment with cocaine concentration-dependently inhibited nicotine-induced current with an IC50 of 1.5 Î¼M. Kinetic analysis showed that cocaine accelerated Î±3Î²4-nAChR desensitization, which caused a reduction of the amplitude of nicotine-induced currents. Co-application of nicotine and cocaine (1.5 Î¼M) depressed the maximum response on the nicotine concentration-response curve without changing the EC50 value, suggesting a non-competitive mechanism. The cocaine-induced inhibition of nicotine response exhibited both voltage- and use-dependence, suggesting an open-channel blocking mechanism. Furthermore, intracellular application of GDP-Î²S (via recording electrode) did not affect cocaine-induced inhibition, suggesting that cocaine did not alter receptor internalization. Moreover, intracellular application of cocaine (30 ÂµM) failed to alter the nicotine response. Finally, cocaine (1.5 Î¼M) was unable to inhibit the nicotine-induced inward current in heterologous expressed Î±6/Î±3Î²2Î²3-nAChRs and Î±4Î²2-nAChRs expressed in human SH-EP1 cells. Collectively, our results suggest that cocaine is a potent blocker for native Î±3Î²4-nAChRs expressed in SH-SY5Y cells.
Acta Pharmacologica Sinica
Digital Object Identifier (DOI)
Ma, Ze gang; Jiang, Nan; Huang, Yuan bing; Ma, Xiao kuang; Eaton, Jason Brek; Gao, Ming; Chang, Yong; Lukas, Ronald J.; Whiteaker, Paul; Neisewander, Janet; and Wu, Jie, "Cocaine Potently Blocks Neuronal Î±3Î²4 Nicotinic Acetylcholine Receptors In Sh-Sy5Y Cells" (2019). Neurobiology. 382.