Subunit composition and quantitative importance of GABAA receptor subtypes in the cerebellum of mouse and rat

Abstract

In cerebellum, 13 different GABAA receptor subunits are expressed. The number of different receptor subtypes formed in this tissue, their subunit composition and their quantitative importance so far has not been determined. In the present study, immunodepletion by immunoaffinity chromatography, as well as immunoprecipitation and western blot analysis was performed using 13 different subunit-specific antibodies to provide an overview on the subunit composition and abundance of GABAA receptor subtypes in mouse and rat cerebellum. Results obtained indicate that α 1βxγ2, α1α 6βxγ2, α6β xγ2, α6βxδ and α1α6βxδ are the major GABAA receptor subtypes present in the cerebellum. In addition, small amounts of α1βxδ receptors and a series of minor receptor subtypes containing α2, α 3, α4, α5, γ1 or γ3 subunits are also present in the cerebellum. Whereas the abundance of α1α6βxγ 2, α6βxδ and α 1α6βxδ receptors is different in mouse and rat cerebellum, that of other receptors is quite similar in these tissues. Data obtained for the first time provide an overview on the GABA A receptor subtypes present in the cerebellum and represent the basis for further studies investigating changes in receptor expression and composition under pathological conditions.