Radioligand Competition Binding Assay: The affinity of the test compounds was determined by radioligand competition binding assay, using the known compound [3H]Ro-15-1788 (Flumazenil) (Perkin Elmer, 85.4 Ci/mmol) and the human recombinant GABA A receptor containing the alpha2, beta2, and gamma3 subunits.Membranes were prepared from HEK cells expressing hGABA A alpha2beta2- gamma3 receptor, and validated to ascertain protein concentration, receptor expression and to determine the Kd of the flumazenil as well as the Ki of a standard set of compounds before being used to test new compounds.The assay was carried out in 96 well plates; testing compounds using a 10 point semi-log dilution range from 19 uM top concentration. 100 ul of radioligand and 100 ul of membrane in 50 mM Tris-HCI and 0.05% F127 with 1 ul of test compound was incubated for 2 hours to allow the reaction to achieve equilibrium, and then harvested onto filter plates, dried and counted on a TopCount NXT. The data was analysed, and the Ki values were presented.
Positive allosteric modulation of human GABAA alpha1/beta3/gamma2 expressed in HEK293 cells assessed as increase in GABA-stimulated chloride current response at 100 times Ki measured after 15 secs by QPatch electrophysiology method relative to GABA
Positive allosteric modulation of human GABAA alpha2/beta2/gamma2 expressed in HEK293 cells assessed as increase in GABA-stimulated chloride current response at 100 times Ki measured after 15 secs by QPatch electrophysiology method relative to GABA