Abstract
Purpose:
Previous studies have shown that correlated neural activity is essential for axon growth of developing retinal ganglion cells (RGCs), and electrical activity can mimic this effect and promote RGC axon growth. However, it is not known if correlated neural activity and electrical activity are equivalent in facilitating axon growth of ganglion cells in the intact retina. The present study was aimed to examine the mechanism underlying the activity dependent neurite outgrowth in the retinal explant preparation.
Methods:
Retinal explants from P2-P14 mice were cultured with or without BDNF in the Cell-Tak coated coverslips for 5 days to study the capacity of RGC neurite outgrowth. To block Stage II retinal wave specifically, DHbetaE was added in culture medium. To provide whole field electrical activity to the retina, the multi-electrode array (MEA) was used to culture the retinal explants and deliver the electrical stimulation.
Results:
The neurite outgrowth ability in P2-P5 retinal explants was similar in culture medium with or without DHbetaE, which suggests that the presence of Stage II retinal wave is not required for RGC axon growth. However, the capacity of neurite outgrowth was significantly enhanced when the retinal explants were electrically stimulated by MEA, which indicates that electrical activity can promote neurite outgrowth effectively.
Conclusions:
The fact that DHbetaE selectively blocks the retinal wave but not the spontaneous activity, thus no effect on neurite outgrowth, and the observation that whole field electrical stimulation enhanced RGC axon growth, suggest that correlated activity pattern is not essential for neurite extension during development, rather spontaneous neural activity and exogenously applied electrical activity are more important in promoting axon growth.