<prompt> All of the following act through GABA except -PhenobarbitoneCarbamazepeneZopicloneMuscimol  <response>: Ans. is b i.e., Carbamazepene Gaba receptorso There are two types of GABA receptorsGABAa receptor - Intrinsic ion channel -increases Cl conduction.GABAb receptor - G protein coupled receptor - hyperpolarizes neurones by increasing K conductance and altering Ca2 flux. 