Detachment of cultured neurons from substratum by astrocytic membrane-associated activity. Implications for CNS regeneration?

Abstract In primary cultures of dissociated cells from 6-day-old rat cerebellum, astrocytes proliferated and grew under the initially formed network of neurons. The growing astrocytes invaded the culture growth surface, while the neurons detached from the substratum and died. By 8 days after plating a confluent layer of astrocytes has taken over the entire growth surface area and neurons have disappeared. Membrane fractions prepared from astrocytes of 8-day-old cultures, have led to detachment of growing neurons. After 2 days in the presence of membrane fractions, about 70% of the neurons disappeared and many of the remaining ones had detached or retracted processes. The results indicate that the well-known phenomenon of disappearance of neurons from mixed primary CNS cultures, is probably caused by a membrane-associated activity of the proliferating astrocytes which can disturb neuron-substratum attachments. Our in vitro study implies that astrocytes may have a membrane-associated activity which is expressed under certain conditions and can disturb the contacts of growing or regenerating axons with their growth substrata.