Effects of phenothiazine-class antipsychotics on the function of α7-nicotinic acetylcholine receptors

Abrar Ashoor, Dietrich Lorke, Syed M. Nurulain, Lina Al Kury, Georg Petroianu, Keun Hang Susan Yang, Murat Oz

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The effects of phenothiazine-class antipsychotics (chlorpromazine, fluphenazine, phenothiazine, promazine, thioridazine, and triflupromazine) upon the function of the cloned α 7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes were tested using the two-electrode voltage-clamp technique. Fluphenazine, thioridazine, triflupromazine, chlorpromazine, and promazine reversibly inhibited acetylcholine (100 μM)-induced currents with IC 50 values of 3.8; 5.8; 6.1; 10.6 and 18.3 μM, respectively. Unsubstituted phenothiazine did not have a significant effect up to a concentration of 30 μM. Inhibition was further characterized using fluphenazine, the strongest inhibitor. The effect of fluphenazine was not dependent on the membrane potential. Fluphenazine (10 μM) did not affect the activity of endogenous Ca 2 +-dependent Cl - channels, since the extent of inhibition by fluphenazine was unaltered by intracellular injection of the Ca 2 + chelator BAPTA and perfusion with Ca 2 +-free bathing solution containing 2 mM Ba 2 +. Inhibition by fluphenazine, but not by chlorpromazine was reversed by increasing acetylcholine concentrations. Furthermore, specific binding of [ 125I] α-bungarotoxin, a radioligand selective for α 7-nicotinic acetylcholine receptor, was inhibited by fluphenazine (10 μM), but not by chlorpromazine in oocyte membranes. In hippocampal slices, epibatidine-evoked [ 3H] norepinephrine release was also inhibited by fluphenazine (10 μM) and chlorpromazine (10 μM). Our results indicate that phenothiazine-class typical antipsychotics inhibit, with varying potencies, the function of α 7-nicotinic acetylcholine receptor.

Original languageBritish English
Pages (from-to)25-32
Number of pages8
JournalEuropean Journal of Pharmacology
Volume673
Issue number1-3
DOIs
StatePublished - 30 Dec 2011

Keywords

  • Antipsychotic
  • Nicotinic receptors
  • Phenothiazine
  • Xenopus oocyte

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