Expression of gabaa receptors by reactive astrocytes in explant and primary cultures of rat cns

Abstract

The presence of GABAA-receptors on astrocytes was studied in explant and primary cultures of rat cerebellum, hippocampus and spinal cord by means of immunohistochemistry. For these studies we have used the monoclonal antibody bd 17 against the β2- and β3-subunits of GABAA-receptor. In explant cultures many neurones were intensely stained with the GABAA-receptor antibody whereas adjacent astrocytes revealed little or no immunoreactivity. In the far outgrowth zone of explant culture, however, many immunostained astrocytes were observed. In primary astrocyte cultures, only a few cells were stained by the antibody. Astrocytes which became reactive after producing an artificial scar or after addition of certain compounds such as dibutyryl cyclic AMP, interleukin-6, basic fibroblast growth factor and kainic acid, also revealed GABAA-receptor immunoreactivity. Furthermore, these astrocytes were intensely stained for glial fibrillary acidic protein and vimentin. From our studies we conclude that only a subpopulation of normal astrocytes are immunopositive for the GABAA-receptor antibody whereas astrocytes which become reactive following injury of the tissue or after addition of dibutyryl cyclic AMP, the cytokine interleukin-6, fibroblast growth factor or the neurotoxin kainic acid express GABAA-sites.