Independent regulation of primary dendritic and axonal growth by maturing astrocytes in vitro

Whereas axon growth is limited in the mature mammalian central nervous system (CNS), dendritic remodeling occurs throughout life. Since glia can regulate neurite growth during development, we tested whether glia from the mature CNS differ in their ability to support axon and dendrite growth. Cortical neurons were co-cultured with neonatal or mature astroglial, and dendrite and axon outgrowth quantified after 5DIV using immunohistochemical techniques. Primary dendritic growth was supported equally well by mature and immature astrocytes. By contrast, mature astrocytes demonstrated a reduced ability to support axon growth. We propose that the independent regulation of axon and dendrite growth by astrocytes provides a means by which the mature nervous system may adjust its function to activity and the environment.