GABA_A receptor subtypes: Dissecting their pharmacological functions

The enhancement of GABA-mediated synaptic transmission underlies the pharmacotherapy of various neurological and psychiatric disorders. GABA_A receptors are pluripotent drug targets that display an extraordinary structural heterogeneity: they are assembled from a repertoire of at least 18 subunits (α1-6, β1-3, γ1-3, δ, ε, θ, ρ1-3). However, differentiating defined GABA_A receptor subtypes on the basis of function has had to await recent progress in the genetic dissection of receptor subtypes in vivo. Evidence that the various actions of allosteric modulators of GABA_A receptors, in particular the benzodiazepines, can be attributed to specific GABA_A receptor subtypes will be discussed. Such discoveries could open up new avenues for drug development.