**2. GABA receptor physiology and GABA ligands**

In 1981, GABAA & GABAB subtypes of GABA were discovered by Hill and Bowery. GABAA was reported as chlorine sensitive ion channel which is allosterically modulated by barbiturates, benzodiazepines, neurosteroids and ethanol. Along with this GABAB receptors couple with Ca<sup>+</sup> and K+ channels via G protein second messenger system. This receptor activation specifically happens through baclofen which is resistant through GABAA modulators [12].

As GABAB receptors are dimeric metabotropic in nature and the structure of pentameric GABAA receptors ideal for allosteric regulation. So research on these receptors is likely to develop novel therapy for the treatment of neurological and psychological disorders [13, 14] (**Figure 1**).
