Afizagabar (S44819) is a first-in-class, competitive, and selective antagonist at the GABA-binding site of the α5-GABAAR, with an IC50 of 585 nM for α5β2γ2 and a Ki of 66 nM for α5β3γ2. Afizagabar enhances hippocampal synaptic plasticity and exhibits pro-cognitive efficacy[1]. Afizagabar (S44819) is a competitive α5-GABAAR antagonist (Kb=221 nM). Afizagabar selectively inhibits extrasynaptic α5-GABAARs of mouse CA1 pyramidal neurons[1]. Afizagabar (1 and 3 mg kg; i.p.) significantly diminishes the marked increase in total errors induced by Scopolamine[1]. [1]. Etherington LA, et al. Selective inhibition of extra-synaptic α5-GABAA receptors by S44819, a new therapeutic agent. Neuropharmacology. 2017;125:353-364.
RO 4938581 is an effective and selective agonist of GABAA α5 inverse (Ki: 4.6 nM for GABAA α5β3γ2a, and shows a lower affinity at α1β3γ2a, α2β3γ2a, α3β3γ2a (Ki, 174, 185, 80 nM, respectively)).
ZK93423 is a potent agonist of benzodiazepine receptor (IC50 = 1 nM) with non-selective between α1-, α2-, α3- and α5-subunit containing GABAA receptors, Ki values are 4.1, 4.2, 6 and 4.5 nM for inhibition of [3H]Ro15-1788 binding to human recombinant α1β3