Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors

The widely used atypical antipsychotic clozapine is a potent competitive antagonist at 5-HT3 receptors which may contribute to its unique psychopharmacological profile. Clozapine binds to 5-HT3 receptors of various species. However, the structural requirements of the respective binding site for cloz...

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Main Authors:	Rammes, Gerhard, Hosp, Christine, Eisensamer, Brigitte, Tanasic, Sascha, Nothdurfter, Caroline, Zieglgänsberger, Walter, Rupprecht, Rainer
Format:	Online
Language:	English
Published:	Public Library of Science 2009
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725292/

id	pubmed-2725292
recordtype	oai_dc
spelling	pubmed-27252922009-08-21 Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors Rammes, Gerhard Hosp, Christine Eisensamer, Brigitte Tanasic, Sascha Nothdurfter, Caroline Zieglgänsberger, Walter Rupprecht, Rainer Research Article The widely used atypical antipsychotic clozapine is a potent competitive antagonist at 5-HT3 receptors which may contribute to its unique psychopharmacological profile. Clozapine binds to 5-HT3 receptors of various species. However, the structural requirements of the respective binding site for clozapine remain to be determined. Differences in the primary sequences within the 5-HT3A receptor gene in schizophrenic patients may result in an alteration of the antipsychotic potency and/or the side effect profile of clozapine. To determine these structural requirements we constructed chimeras with different 5-HT3A receptor sequences of murine and human origin and expressed these mutants in human embryonic kidney (HEK) 293 cells. Clozapine antagonises recombinant mouse 5-HT3A receptors with higher potency compared to recombinant human 5-HT3A receptors. 5-HT activation curves and clozapine inhibition curves yielded the parameters EC50 and IC50 for all receptors tested in the range of 0.6–2.7 µM and 1.5–83.3 nM, respectively. The use of the Cheng-Prusoff equation to calculate the dissociation constant Kb values for clozapine revealed that an extracellular sequence (length 86 aa) close to the transmembrane domain M1 strongly determines the binding affinity of clozapine. Kb values of clozapine were significantly lower (0.3–1.1 nM) for receptors containing the murine sequence and higher when compared with receptors containing the respective human sequence (5.8–13.4 nM). Thus, individual differences in the primary sequence of 5-HT3 receptors may be crucial for the antipsychotic potency and/or the side effect profile of clozapine. Public Library of Science 2009-08-21 /pmc/articles/PMC2725292/ /pubmed/19696922 http://dx.doi.org/10.1371/journal.pone.0006715 Text en Rammes et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Rammes, Gerhard Hosp, Christine Eisensamer, Brigitte Tanasic, Sascha Nothdurfter, Caroline Zieglgänsberger, Walter Rupprecht, Rainer
spellingShingle	Rammes, Gerhard Hosp, Christine Eisensamer, Brigitte Tanasic, Sascha Nothdurfter, Caroline Zieglgänsberger, Walter Rupprecht, Rainer Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
author_facet	Rammes, Gerhard Hosp, Christine Eisensamer, Brigitte Tanasic, Sascha Nothdurfter, Caroline Zieglgänsberger, Walter Rupprecht, Rainer
author_sort	Rammes, Gerhard
title	Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
title_short	Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
title_full	Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
title_fullStr	Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
title_full_unstemmed	Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors
title_sort	identification of a domain which affects kinetics and antagonistic potency of clozapine at 5-ht3 receptors
description	The widely used atypical antipsychotic clozapine is a potent competitive antagonist at 5-HT3 receptors which may contribute to its unique psychopharmacological profile. Clozapine binds to 5-HT3 receptors of various species. However, the structural requirements of the respective binding site for clozapine remain to be determined. Differences in the primary sequences within the 5-HT3A receptor gene in schizophrenic patients may result in an alteration of the antipsychotic potency and/or the side effect profile of clozapine. To determine these structural requirements we constructed chimeras with different 5-HT3A receptor sequences of murine and human origin and expressed these mutants in human embryonic kidney (HEK) 293 cells. Clozapine antagonises recombinant mouse 5-HT3A receptors with higher potency compared to recombinant human 5-HT3A receptors. 5-HT activation curves and clozapine inhibition curves yielded the parameters EC50 and IC50 for all receptors tested in the range of 0.6–2.7 µM and 1.5–83.3 nM, respectively. The use of the Cheng-Prusoff equation to calculate the dissociation constant Kb values for clozapine revealed that an extracellular sequence (length 86 aa) close to the transmembrane domain M1 strongly determines the binding affinity of clozapine. Kb values of clozapine were significantly lower (0.3–1.1 nM) for receptors containing the murine sequence and higher when compared with receptors containing the respective human sequence (5.8–13.4 nM). Thus, individual differences in the primary sequence of 5-HT3 receptors may be crucial for the antipsychotic potency and/or the side effect profile of clozapine.
publisher	Public Library of Science
publishDate	2009
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725292/
_version_	1611441554430361600

Identification of a Domain which Affects Kinetics and Antagonistic Potency of Clozapine at 5-HT3 Receptors

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