DEVELOPMENTAL PATTERN OF GFAP AND VIMENTIN GENE-EXPRESSION IN RAT-BRAIN AND IN RADIAL GLIAL CULTURES

In the present study we analyze the events which occur during the earl y stages of astrogliogenesis by examining the pattern of both GFAP and vimentin gene expression and their corresponding immunoreactive prote ins during rat brain development. This study was carried out ''in vivo '' (whole brain) and ''in vitro'' (primary culture of radial glia) usi ng immunofluorescence, immunoblotting, and Northern blot analysis. Our results demonstrate that although GFAP immunostaining appeared late i n gestation and at day 5 in radial glia cultures, GFAP mRNA expression was first detected, at very low levels, on fetal (F) day 15 and incre ased to F21. During postnatal development a striking increase in GFAP and its encoding messenger occurs. In contrast, the levels of vimentin and its mRNA expression were very high during the fetal stage (F15 to F21). Thereafter vimentin expression declined during postnatal (P) de velopment until P21 and then remained constant at adult levels. In con trast, an increase in vimentin expression was observed in glial cells throughout the entire culture period. The biological significance of t he developmental patterns of GFAP and vimentin expression in astroglia l cells during brain development is discussed. (C) 1995 Wiley-Liss, In c.