EVIDENCE FOR DOPAMINE D-2 RECEPTOR MESSENGER-RNA EXPRESSION BY STRIATAL ASTROCYTES IN CULTURE - IN-SITU HYBRIDIZATION AND POLYMERASE CHAIN-REACTION STUDIES

The expression of dopamine D-2 receptor mRNA in cultured rat striatal and cerebellar astrocytes was examined by in situ hybridization (ISH) and polymerase chain reaction (PCR). Cells double-labelled for glial fibrillary acidic protein (GFAP) immuno-histochemistry and dopamine D-2 receptor mRNA (ISH) provide evidence that striatal but not cerebellar astrocytes express the dopamine D-2 gene in vitro. These results were confirmed by polymerase chain reaction studies. As judged by GFAP immunostaining and morphology of the cells, this gene is almost exclusively expressed by astrocytes type 1. The expression of dopamine D-2 receptor mRNA by striatal astrocytes in vitro, as found in this study, brings thus evidences for the existence of dopamine D-2 receptors in such glial cells. This had been previously suggested from ligand binding studies but the typical dopaminergic nature of the binding to striatal astrocytes was left questionable. Our results with molecular biological techniques thus suggest that striatal dopamine might modulate the functions of striatal astrocytes.