Article

Cocaine potently blocks neuronal α3β4 nicotinic acetylcholine receptors in SH-SY5Y cells

Authors: Ze-gang Ma1,2, Nan Jiang2,3, Yuan-bing Huang4, Xiao-kuang Ma2,5, Jason Brek Eaton2, Ming Gao2, Yong-chang Chang2, Ronald J Lukas2, Paul Whiteaker2, Janet Neisewander6, Jie Wu1,2,4,5
1 Department of Physiology, Institute of Brain Science and Disorders, Medical College of Qingdao University, Qingdao 266071, China
2 Division of Neurobiology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ 85013, USA
3 Department of Ophthalmology, the Affiliated Hospital of Qingdao University, Qingdao 266003, China
4 Department of Neurology, Yunfu People’s Hospital, Yunfu 527300, China
5 Department of Physiology, Shantou University Medical College, Shantou 515004, China
6 School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
Correspondence to: Jie Wu: jie.wu@DignityHealth.org,
DOI: 10.1038/s41401-019-0276-y
Received: 6 January 2019
Accepted: 23 June 2019
Advance online: 9 August 2019

Abstract

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, α3β4-nAChR expressed in native SH-SY5Y cells. α3β4-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 µM. Pre-treatment with cocaine concentration-dependently inhibited nicotine-induced current with an IC50 of 1.5 μM. Kinetic analysis showed that cocaine accelerated α3β4-nAChR desensitization, which caused a reduction of the amplitude of nicotine-induced currents. Co-application of nicotine and cocaine (1.5 μM) 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-βS (via recording electrode) did not affect cocaine-induced inhibition, suggesting that cocaine did not alter receptor internalization. Moreover, intracellular application of cocaine (30 µM) failed to alter the nicotine response. Finally, cocaine (1.5 μM) was unable to inhibit the nicotine-induced inward current in heterologous expressed α63β2β3-nAChRs and α4β2-nAChRs expressed in human SH-EP1 cells. Collectively, our results suggest that cocaine is a potent blocker for native α3β4-nAChRs expressed in SH-SY5Y cells.
Keywords: cocaine; nicotinic acetylcholine receptor; patch-clamp; open-channel block; SH-SY5Y cells

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