General anesthetic actions on GABA_A receptors in vivo are reduced in phospholipase C-related catalytically inactive protein knockout mice

Purpose: The aim of this study was to investigate the action of general anesthetics in phospholipase C-related catalytically inactive protein (PRIP)-knockout (KO) mice that alter GABA_A receptor signaling.

Methods: PRIP regulates the intracellular trafficking of β subunit-containing GABA_A receptors in vitro. In this study, we examined the effects of intravenous anesthetics, propofol and etomidate that act via β subunit-containing GABA_A receptors, in wild-type and Prip-KO mice. Mice were intraperitoneally injected with a drug, and a loss of righting reflex (LORR) assay and an electroencephalogram analysis were performed.

Results: The cell surface expression of GABA_A receptor β3 subunit detected by immunoblotting was decreased in Prip-knockout brain compared with that in wild-type brain without changing the expression of other GABA_A receptor subunits. Propofol-treated Prip-KO mice exhibited significantly shorter duration of LORR and had lower total anesthetic score than wild-type mice in the LORR assay. The average duration of sleep time in an electroencephalogram analysis was shorter in propofol-treated Prip-KO mice than in wild-type mice. The hypnotic action of etomidate was also reduced in Prip-KO mice. However, ketamine, an NMDA receptor antagonist, had similar effects in the two genotypes.

Conclusion: PRIP regulates the cell surface expression of the GABA_A receptor β3 subunit and modulates general anesthetic action in vivo. Elucidation of the involved regulatory mechanisms of GABA_A receptor-dependent signaling would inform the development of safer anesthetic therapies for clinical applications.