Apolipoprotein E (ApoE) is involved in brain development and repair. In order to investigate the contribution of astrocytes to ApoE gene expression, we investigated ApoE mRNA levels in mouse brain and in astroglial primary cultures during postnatal development and in two different trauma models. A biphasic developmental pattern was observed consisting in an increased expression during the first 2 weeks and a decrease in the later stages. A similar pattern was obtained in highly enriched primary cultures, suggesting ApoE mRNA location in the astroglial population and an important role for ApoE in astroglial development and/or function. ApoE gene expression could be modulated in culture by administration of lipopolysaccharides (LPS) which mimics a bacterial infection, or in reactive astrocytes consequent to a chemically induced lesion, suggesting that ApoE might be involved in the inflammatory events consequent to both situations. These results underline the importance of astrocytes in regenerative processes.