GABAA receptors: structure and function in the basal ganglia

Abstract

γ-Aminobutyric acid type A (GABAA) receptors, the major inhibitory neurotransmitter receptors responsible for fast inhibition in the basal ganglia, belong to the superfamily of "cys-cys loop" ligand-gated ion channels. GABAA receptors form as pentameric assemblies of subunits, with a central Cl- permeable pore. On binding of two GABA molecules to the extracellular receptor domain, a conformational change is induced in the oligomer and Cl-, in most adult neurons, moves into the cell leading to an inhibitory hyperpolarization. Nineteen mammalian subunit genes have been identified, each showing distinct regional and cell-type-specific expression. The combinatorial assembly of the subunits generates considerable functional diversity. Here we place the focus on GABAA receptor expression in the basal ganglia: striatum, globus pallidus, substantia nigra and subthalamic nucleus, where, in addition to the standard α1β2/3γ2 receptor subtype, significant levels of other subunits (α2, α3, α4, γ1, γ3 and δ) are expressed in some nuclei. © 2007 Elsevier B.V. All rights reserved.