Mechanisms of Propofol Anesthesia

DESCRIPTION: (taken from the application). The overall Aim of Project 1 is to understand the molecular basis of the actions of the anesthetic propofol. It has recently shown that mutations in the a subunit of the gamma-aminobutyric acid type A receptor (GABAA-R) can alter the allosteric modulation of the receptor by inhaled anesthetics. Preliminary work suggests that the beta subunit is crucial for the actions of propofol at this receptor. We now propose to test the overall hypothesis that propofol acts at a specific binding pocket in the GABAA-R, that is important for the anesthetic actions of the drug, and which can be partially characterized by a combination of structure-activity studies and site-directed mutagenesis. We will study the structure-activity relationship (SAR) within a series of propofol analogs for loss of righting reflex (LORR) in Xenopus laevis tadpoles. We will also study the SAR within a series of propofol analogs for the enhancement of submaximal GABA responses, and for direct receptor activation, in recombinant alpha1 beta2 gamma2s GABAA-R. The resulting potency measurements will be compared with log P and other physicochemical properties (volume, polarity etc.) of these compounds and with data from the SAR established for LORR. We will compare the effects of propofol and its analogs at the wild-type alpha1beta2gamma2s GABAA receptors with the effects of these compounds at alpha1beta2(M286W)gamma2s GABAA receptors and a series of related mutated GABAA receptors. The hypothesis to be examined is that the structural requirements for propofol activity at GABAA receptors can be altered by specific mutations that affect the physicochemical properties of a putative propofol-binding site. In collaboration with Dr. Hopfinger, we will probe the requirements for propofol activity in producing LORR and at the GABAA receptor using the techniques of quantitative structure-activity relationship (QSAR) analysis, and then perform virtual high-throughput screening (VHTS) of a large "virtual library" of compounds assembled using computational combinatorial chemistry. The hypothesis to be examined is that VHTS can be used to suggest novel propofol analogs for subsequent synthesis and biological testing.