Astrocytes are the most versatile cells of the neural tissue. Numerous astrocytic functions--such as protection from oxidative damage, catabolism of neuroactive D-amino acids acting as neuromodulators, synthesis and catabolism of some lipid molecules, and, possibly, gluconeogenesis--reside in peroxisomes. The expression of several peroxisomal enzymes, particularly those of the acyl-CoA beta-oxidation pathway, is regulated by a class of ligand-activated transcription factors, known as peroxisome proliferator-activated receptors (PPARs), acting on their target genes as heterodimers with the retinoid X receptors (RXRs). In this work, primary and secondary cultures of astrocytes from the cerebral cortices and cerebella of neonatal rats (2 and 7 days of postnatal age) were utilized to investigate the expression of peroxisomal enzymes, PPAR and RXR isotypes (alpha, beta and gamma), by both biochemical and immunological methods. The results obtained demonstrate that astrocytes in vitro express peroxisomal enzymes, PPARs, and RXRs and that differences dependent on brain area, animal age, and culture time are reminiscent of the in vivo situation. Therefore, primary cultures of astrocytes and, particularly, high purified subcultures may constitute a useful model for further studies aimed to gain further insights into the roles of peroxisomes and PPARs related to lipid and glucose metabolism in these cells.