Open AccessEffects of cyclothiazide on GluR1/AMPA receptors
Author(s) -
Sergio Fucile,
Ricardo Miledi,
Fabrizio Eusebi
Publication year - 2006
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.0511063103
Subject(s) - ampa receptor , ionotropic effect , desensitization (medicine) , biophysics , agonist , receptor , allosteric regulation , chemistry , long term potentiation , ion channel , allosteric modulator , pharmacology , patch clamp , gating , glutamate receptor , microbiology and biotechnology , biology , biochemistry
Cyclothiazide (CTZ), a positive allosteric modulator of ionotropic alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors, is used frequently to block the desensitization of both native and heterologously expressed AMPA receptors. Specifically, CTZ is known to produce a fast inhibition of AMPA receptor desensitization and a much slower potentiation of the AMPA current. By using patch-clamp techniques, the effects of CTZ were studied in HEK 293 cells stably transfected with the rat flip GluR1 subunit. Upon CTZ treatment, we found an increased apparent affinity for the agonist, a slow whole-cell current potentiation, a fast inhibition of desensitization, and a lengthening of single-channel openings. Furthermore, we show that CTZ alters the channel gating events modifying the relative contribution of different single-channel classes of conductance (gamma), increasing and decreasing, respectively, the contributions of gammaM (medium) and gammaL (low) without altering that of the gammaH (high) conductance channels. We also present a kinetic model that predicts well all of the experimental findings of CTZ action. Finally, we suggest a protocol for standard cell treatment with CTZ to attain maximal efficacy of CTZ on GluR1 receptors.