Distribution of GABAA receptor subunits in the human brain

Abstract

GABAA receptors (GABAARs) are pentameric subunit complexes, which surround a central chloride ion channel. GABAAR subunits are distributed widely throughout the human brain and spinal cord and are activated by the extensive GABAergic inhibitory system that exists throughout the human CNS. These GABAAR complexes are comprised of combinations of subunits derived from a total of 19 different subunits assembled from a variety of different subunit classes (α1-6, β1-3, γ1-3, δ, θ and π). The most widespread subunit in the human brain is the α1 subunit and this is commonly associated with the β2 or β3 subunit and γ2 subunits. Other α subunits (α1-5) are distributed variably throughout the basal ganglia, hippocampus, brainstem and spinal cord in a complex fashion, and these are associated in varying degrees with β and γ subunits. Less common subunits δ, θ and π have a limited distribution, which has not been well documented in human brain. The information described in this chapter is based on published human data using mRNA probes and from immunohistochemical staining using post-mortem human brain sections with antibodies directed against various GABAA receptor subunits.