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Open Access Research article

Mutational analysis of molecular requirements for the actions of general anaesthetics at the γ-aminobutyric acidA receptor subtype, α1β2γ2

Roberta Siegwart, Karin Krähenbühl, Sachar Lambert and Uwe Rudolph*

Author Affiliations

Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

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BMC Pharmacology 2003, 3:13  doi:10.1186/1471-2210-3-13

Published: 12 November 2003

Abstract

Background

Amino acids in the β subunit contribute to the action of general anaesthetics on GABAA receptors. We have now characterized the phenotypic effect of two β subunit mutations in the most abundant GABAA receptor subtype, α1β2γ2.

Results

The β2(N265M) mutation in M2 decreased the modulatory actions of propofol, etomidate and enflurane, but not of alphaxalone, while the direct actions of propofol, etomidate and alphaxalone were impaired. The β2(M286W) mutation in M3 decreased the modulatory actions of propofol, etomidate and enflurane, but not of alphaxalone, whereas the direct action of propofol and etomidate, but not of alphaxalone, was impaired.

Conclusions

We found that the actions of general anaesthetics at α1β2(N265M)γ2 and α1β2(M286W)γ2 GABAA receptors are similar to those previously observed at α2β3(N265M)γ2 and α2β3(M286W)γ2 GABAA recpetors, respectively, with the notable exceptions that the direct action of propofol was decreased in α1β2(M286W)γ2 receptors but indistinguishable form wild type in α2β3(M286W)γ2 receptors and that the direct action of alphaxalone was decreased in α1β2(N265M)γ2 but not α2β3(N265M)γ2 receptors and indistinguishable form wild type in α1β2(M286W)γ2 receptors but increased in α2β3(M286W)γ2 receptors. Thus, selected phenotypic consequences of these two mutations are GABAA receptor subtype-specific.