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Original Article

Korean J Physiol Pharmacol 2019; 23(6): 509-517

Published online November 1, 2019 https://doi.org/10.4196/kjpp.2019.23.6.509

Copyright © The Korean Journal of Physiology & Pharmacology.

Selective serotonin reuptake inhibitor escitalopram inhibits 5-HT3 receptor currents in NCB-20 cells

Yong Soo Park1 and Ki-Wug Sung2,*

Departments of 1Anatomy and 2Pharmacology, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea

Correspondence to:Ki-Wug Sung
E-mail: sungkw@catholic.ac.kr

Received: August 6, 2019; Revised: October 9, 2019; Accepted: October 10, 2019

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Escitalopram is one of selective serotonin reuptake inhibitor antidepressants. As an S-enantiomer of citalopram, it shows better therapeutic outcome in depression and anxiety disorder treatment because it has higher selectivity for serotonin reuptake transporter than citalopram. The objective of this study was to determine the direct inhibitory effect of escitalopram on 5-hydroxytryptamine type 3 (5-HT3) receptor currents and study its blocking mechanism to explore additional pharmacological effects of escitalopram through 5-HT3 receptors. Using a whole-cell voltage clamp method, we recorded currents of 5-HT3 receptors when 5-HT was applied alone or co-applied with escitalopram in cultured NCB-20 neuroblastoma cells known to express 5-HT3 receptors. 5-HT induced currents were inhibited by escitalopram in a concentration-dependent manner. EC50 of 5-HT on 5-HT3 receptor currents was increased by escitalopram while the maximal peak amplitude was reduced by escitalopram. The inhibitory effect of escitalopram was voltage independent. Escitalopram worked more effectively when it was co-applied with 5-HT than pre-application of escitalopram. Moreover, escitalopram showed fast association and dissociation to the open state of 5-HT3 receptor channel with accelerating receptor desensitization. Although escitalopram accelerated 5-HT3 receptor desensitization, it did not change the time course of desensitization recovery. These results suggest that escitalopram can inhibit 5-HT3 receptor currents in a non-competitive manner with the mechanism of open channel blocking.

Keywords: Depression, Escitalopram, Patch clamp, Selective serotonin reuptake inhibitor, 5-hydroxytriptamine3 receptor