REDUCTION OF THE MICROGLIAL CELL NUMBER IN RAT PRIMARY GLIAL-CELL CULTURES BY EXOGENOUS ADDITION OF DIBUTYRYL CYCLIC ADENOSINE-MONOPHOSPHATE

The present work examined the effects induced by dibutyryl cyclic aden osine monophosphate (dB-cAMP) on microglial cells in primary glial cel l cultures from newborn rats. Microglial cells were identified by OX42 immunohistochemistry and nucleoside diphosphatase histochemistry. Dou ble staining for astrocytes was carried out by combination with glial fibrillary acidic protein immunolabeling. Addition of 0.25 mM dB-cAMP to the cultures decreased the microglial cell number about sixfold. Th e findings suggest that the effect of dB-cAMP on the microglial cells might be either a direct action of dB-cAMP on the microglial cells or an indirect effect mediated by the astroglial cells.