S-100 protein in monolayer cultures of glial cells: Basal level in primary and secondary cultures

Monolayer cultures of astrocytes from newborn rat brain hemispheres have been analysed for the glial-specific protein S-100, during their growth cycle. In primary cultures S-100 protein level increases with a pattern close to that observed with rat brain hemispheres in vivo. This finding suggests that some biochemical maturation of the astrocytes occurs in vitro. In secondary cultures the level of S-100 protein decreases and then increases at the end of the proliferation phase. This modulation, similar to that observed in a clonal culture of tumor cells from rat brain (C6) provides a model to study the relationship between gene expression and the phase of growth of the cells and will allow parallel investigations in normal and tumor cells.