Dibutyryl cAMP, interleukin-1 beta, and macrophage conditioned medium enhance the ability of astrocytes to promote neurite growth.

Astrocytes purified from the neonatal rat brain were cultured for up to 3 weeks prior to being treated with agents that can induce reactive changes in astrocytes. These agents included dibutyryl cAMP, interleukin-1 beta, and macrophage conditioned media. After treating astrocytes for 3 days, the agents were removed and the ability of the astrocytes to support neurite growth was assessed by plating neonatal rat cerebellar cortical neurons. All the agents increased the ability of astrocytes to support the growth of long neurites. This was particularly evident with astrocytes treated with dibutyryl cAMP and LPS macrophage-conditioned medium. These results provide direct evidence that the reactive changes induced in astrocytes in this in vitro model might aid the growth of neurites. Similar changes may underlie the injury-induced axonal sprouting that occurs in vivo.