Induction of dendritic spine proliferation by an astrocyte secreted factor.

A number of neuron-supporting functions have been ascribed to astrocytes. In this study we found that a proliferation of Purkinje cell dendritic spines, a target site for presynaptic axon terminals, was induced in cytosine arabinoside-treated cerebellar cultures by exposure to astrocyte-conditioned medium. This result suggests that astrocytes may instigate the elaboration of postsynaptic neuronal elements prior to the appearance of axons. This may be an important mechanism in neural development, postdevelopmental neuroplastic change, or regeneration.