Skip to main content
padlock icon - secure page this page is secure

Contrasting Effects of the γ-Aminobutyric Acid Type A Receptor β3 Subunit N265M Mutation on Loss of Righting Reflexes Induced by Etomidate and the Novel Anesthetic Barbiturate R–mTFD-MPAB

Buy Article:

$62.00 + tax (Refund Policy)


Previous studies have shown that etomidate modulates γ-aminobutyric acid type A receptors by binding at the β+ subunit interface within the transmembrane domain of receptors that incorporate β2 or β3 subunits. Introducing an asparagine-to-methionine (N265M) mutation at position 265 of the β3 subunit, which sits within the etomidate-binding site, attenuates the hypnotic effect of etomidate in vivo. It was reported recently that the photoactivatable barbiturate R–mTFD-MPAB also acts on γ-aminobutyric acid type A receptors primarily by binding to a homologous site at the γ-β interface. Given this difference in drug-binding sites established by the in vitro experiments, we hypothesized that the β3-N265M–mutant mice would not be resistant to the anesthetic effects of R–mTFD-MPAB in vivo, whereas the same mutant mice would be resistant to the anesthetic effects of R-etomidate.


We measured the effects of IV injection of etomidate and R–mTFD-MPAB on loss and recovery of righting reflex in wild-type mice and in mice carrying the β3-N265M mutation.


Etomidate-induced hypnosis, as measured by the duration of loss of righting reflex, was attenuated in the N265M knock-in mice, confirming prior results. By contrast, recovery of balance and coordinated movement, as measured by the ability to maintain all 4 paws on the ground, was unaffected by the mutation. Neither hypnosis nor impairment of coordinated movement produced by the barbiturate R–mTFD-MPAB was affected by the mutation.


The findings confirmed our hypothesis that mutating the etomidate-binding site would not alter the response to the barbiturate R-mTFD-MPAB. Furthermore, we confirmed previous studies indicating that etomidate-induced hypnosis is mediated in part by β3-containing receptors. We also extended previous findings by showing that etomidate-impaired balance and coordinated movement are not mediated by β3-containing receptors, thus implicating β2-containing receptors in this end point.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: November 1, 2016

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more