GABAA receptors are pentameric ligand-gated ion channels that are activated by the major inhibitory neurotransmitter in the mammalian brain, g-aminobutyric acid (GABA).Binding of GABA results in the opening of a chloride ion selective pore, thus hyperpolarizing the postsynaptic neuron and decreasing the likelihood of action-potential firing. As such, GABAA receptors are a prominent target for anesthetic, hypnotic, and anticonvulsant drugs.