SB-205384 is a selective and positive GABAA receptor modulator with EC50 values of 280, 695 and 730 nM on α6, α3 and α5-subunit-containing receptors, respectively. g-Aminobutyric acid (GABA) acting on the GABAA receptor can inhibit synaptic transmission in the mammalian central nervous system. Ligands that modulate the function of g-aminobutyric acid A (GABAA) receptor gated chloride channels have hypnotic, anaesthetic, anxiolytic, anticonvulsant and sedative actions. SB-205384 can slow the decay rate on GABAA currents in oocytes expressing human GABAA subunits, which is also seen on native GABA-activated currents in rat neurons . The isoforms containing the a3, a5, and a6 subunits show significantly greater enhancement of the current by SB-205384 and the receptors with the a6-subunit had the greatest sensitivity to SB-205384 . In rat cerebellum granule cells, SB-205384 dramatically pro-longed the half-life for decay of the GABA response in a concentration-dependent manner. The half-life of decay was increased about 10 fold compared with control responses at the highest concentration of SB-205384 used. Also, SB-205384 did not increase the maximum current evoked by 100 mM GABA but the half-life decay was dramatically increased, as saw at the lower dose of 1 mM GABA .