DIFFERENCES BETWEEN REACTIVE ASTROCYTES AND CULTURED ASTROCYTES TREATED WITH DI-BUTYRYL-CYCLIC AMP

The long-standing idea that astrogliosis acts as a barrier for regener ating axons could be tested if an in vitro model of reactive astrocyte s were available. The morphology and intermediate filament content of cultured perinatal astrocytes treated with di-butyryl-cyclic-AMP are r eminiscent of reactive astrocytes evoked by injury. Thus, they have be en proposed as a reactive astrocyte in vitro model. However, we show h ere that di-butyryl-cyclic-AMP-treated astrocytes are much closer to u ntreated neonatal cells than to reactive astrocytes in vivo, when usin g other immunohistochemical markers of living reactive glia (i.e. EGF receptor or laminin). Furthermore, living di-butyryl-cyclic-AMP-treate d astrocytes and untreated, flat, epithelioid cells, as well as their purified plasma membranes, had similar neurite outgrowth promoting pro perties, whereas membranes from gliotic tissue enriched in reactive as trocytes inhibited neurite outgrowth. Our observations indicate that d i-butyryl-cyclic-AMP treatment leads, at best, to a morphological mode l of reactive cells that does not share many properties of reactive as trocytes in vivo.