Aging-related subunit expression changes of the GABAA receptor in the rat hippocampus

Abstract Aging-related changes in the subunit expression of some hippocampal GABA A receptors have been found. Quantitative in situ hybridization has revealed that α 1 subunit messenger RNA expression was significantly increased in the hippocampus (34%) of old rats. The largest increases were observed in the dentate gyrus (76%) and in the CA1 field (30%). Quantitative immunocytochemistry also showed increased protein expression of the α 1 subunit in the dentate gyrus (19%) and CA1 (14%) of old rats. The increased α 1 messenger RNA and protein expression led to increased proportions of assembled GABA A receptors that contained α 1 subunits, as revealed by quantitative immunoprecipitation of [ 3 H]flunitrazepam and [ 3 H]muscimol binding. In contrast, there were no significant changes in the expression of β 2 , β 3 and total γ 2 (γ 2S + γ 2L ) subunits, although a slightly increased expression of γ 2L peptide was detected in the hippocampus proper (7%), but not in the dentate gyrus. The results are consistent with the notion that in the rat hippocampus there is an aging-related change in the subunit composition of some GABA A receptors. Copyright © 1996 IBRO. Published by Elsevier Science Ltd.