GABA (γ-aminobutyric acid) is the major inhibitory neurotransmitter in the brain. Its production, release, reuptake and metabolism occur in the nervous system.¹ 

The GABA transmitter interacts with two major types of receptors: ionotropic GABA_A (GABA_AR) and metabotropic GABA_B receptors. The GABA_AR belong to the ligand gated ion channel superfamily.² 

The GABA_AR, is a heteropentamer, with all of its five subunits contributing to the pore formation. To date, eight subunit isoforms were cloned: α, β, γ, δ, ε, π, θ, and ρ.¹ Six α subunit isoforms were described to exist in mammals (α1-α6). The native GABAA receptor, in most cases, consists of 2α, 2β and 1γ submit. The α subunit is the most common subunit and is expressed ubiquitously. It determines the affinities for allosteric ligands shown by GABA_AR. 

α2-Subunit mRNA is strongly expressed only in the hippocampus and the hypothalamus. It occurs very early in rat brain development and declines in adulthood. 

The failure to complete the normal transition between the α-subunits that are highly expressed in early development (α2, α3, α5) to those expressed in adulthood (α1) might play a major role in the development of temporal lobe epilepsy.³