Growth factor-estradiol interaction on DNA labeling and cytoskeletal protein expression in cultured rat astrocytes

Growth factors are major signaling agents regulating neuron-glia dialogue. Epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), insulin growth factor-I (IGF-I) and insulin (INS) induce neuronal and astroglial cell proliferation and differentiation. This is true also for estrogens that influence astrocytes and exert neuroprotectant activity. In this study interactions between growth factors and estradiol on DNA labeling and glial fibrillary acidic protein (GFAP) and vimentin expression in cultured astrocytes were investigated. DNA labeling was significantly stimulated by bFGF pretreatment followed by 24 h estradiol and EGF or IGF-I or INS added in the last 12 h. Western blotting showed also a modulation of GFAP and vimentin expression in treated astrocytes. This suggests the occurrence of a crucial growth factor-estradiol interaction on DNA labeling and cytoskeletal protein expression during astrocyte proliferation and differentiation in culture.