GABAA-R are the site of action of a variety of pharmacologically and clinically important drugs. Their interaction with benzodiazepines has been most thoroughly investigated. The location of the benzodiazepine binding site at the α+/γ- interface indicates that the benzodiazepine pharmacology of receptor subtypes is mainly determined by the α and γ isoform forming this site. The classical benzodiazepines, such as diazepam or flunitrazepam, predominantly interact with receptors composed of α1βγ2, α2βγ2, α3βγ2, or α5βγ2. They exhibit no activity on α4βγ2 or α6βγ2 receptors and a reduced activity on receptors containing γ1 or γ3 subunits (Sieghart, 1995; Hevers and Lüddens, 1998). However, the pharmacology of γ1 and γ3 containing receptors so far has not been extensively investigated. The classical benzodiazepines cannot distinguish between the benzodiazepine sites of different GABAA-R subtypes, but over time, some compounds, such as the benzodiazepines quazepam and cinolazepam (Sieghart, 1989) or non-benzodiazepines such as zolpidem, Cl218872, abecarnil, zaleplon and indiplon (for review see Möhler, 2006), have been developed that exhibit a preferential selectivity for α1βγ2 receptors. Most of these compounds exhibit sedative and hypnotic properties. Other compounds,
