LIGHT AND ELECTRON-MICROSCOPIC LOCALIZATION OF GABA-A-RECEPTORS ON CULTURED CEREBELLAR GRANULE CELLS AND ASTROCYTES USING IMMUNOHISTOCHEMICAL TECHNIQUES

GABA(A)-receptors were localized in explant cultures of rat cerebellum and in dissociated primary cultures of rat cerebellar granule cells and rat cerebellar astrocytes using the monoclonal antibody bd-17 directed against the beta-subunit of the GABA(A)/benzodiazepine/chloride channel complex. At the light microscope level specific staining of GABA(A)-receptors was localized in various types of neurones in explant cultures of rat cerebellum using the indirect peroxidase-antiperoxidase (PAP) technique, whereas no specific staining was found in astrocytes. At the electron microscope level labeling of GABA(A)-receptors was observed in the plasma membrane of both the cell bodies and processes in dissociated primary cultures of cerebellar granule cells using an indirect preembedding immunogold staining technique which in contrast to the classical PAP technique allows quantitative estimations to be performed. Quantification of the labeling intensity revealed a higher concentration of GABA(A)-receptors per-mu-m plasma membrane in the cell bodies than in the processes. In discrete areas an extremely high density of the GABA(A)-receptors was observed. No specific labeling of GABA(A)-receptors was observed in dissociated primary cultures of cerebellar astrocytes.