The effects of anesthetics on G-protein-coupled receptors

Although anesthetics have been often used clinically, the mechanisms of action of anesthetics have not yet been clarified. Recently, major advances have been made in our understanding of the physiology and pharmacology of G-protein-coupled receptor (GPCR)-mediated signaling. Several lines of studies have shown that GPCRs are targets for anesthetics and that some anesthetics inhibit the functions of Gq-coupled receptors, including muscarinic acetylcholine (ACh) M1, metabotropic type 5 glutamate, 5-hydroxytryptamine (5-HT) type 2 A, and substance P receptors. Many additional GPCRs have been classified as "orphan" receptors (oGPCRs) because their endogenous ligands have not been identified yet. Given that known GPCRs are targets for anesthetics, these oGPCRs may represent a rich group of receptor targets for anesthetics. This review highlights the effects of anesthetics on Gq-coupled receptors, and discusses whether GPCRs other than Gq-coupled receptors, and proteins that convey GPCR signals are also targets for anesthetics.