This paper presents data on the basal gene expression patterns, determined by microarray analysis, for cultured neonatal and normal adult striatal astrocytes, and for comparison, for astrocytes isolated directly from adult rat striatum (in vivo adult astrocytes). Of the 1176 genes on the Clontech array, 1101 were expressed in one of the three types of astrocyte samples. Nineteen of the genes were expressed only in the astrocytes taken directly from adult rats (in vivo adult). The cultured neonatal astrocytes expressed many genes at a two-fold or greater level than their expression in cultured adult astrocytes, including genes in the adhesion, cytoskeleton, and extracellular matrix (ECM) family, signal transduction genes, and genes related to apoptosis, DNA-binding, and cell cycle regulation. Overall the results support the concept that cultured neonatal astrocytes are more "activated" than cultured adult cells, although the adult cells expressed higher levels of many metabolic enzyme and protease/protease inhibitor genes. Published by Elsevier Ltd.