Abstract
Purpose :
Axons of retinal ganglion cells (RGCs) in the adult mammals fail to regenerate after injury. It has been suggested that some extrinsic factors, such as neural activity, may promote regeneration process. In our previous experiment, it was discovered that slightly increased culture medium concentration as a result of accidentally elevating the 12-well plate temperature below and thus increasing the evaporation rate can significantly promote neurite outgrowth of retinal explants. The present study tested the hypothesis that environmental stress such as slightly elevated osmolarity and temperature can enhance axon regeneration of RGCs in postnatal mice.
Methods :
Two stress conditions were used in this study to assess their effects on neurite outgrowth of retinal explants. One is the increased overall culture medium concentration 1.25 folds (mild stress) or 1.5 folds (strong stress) of the control culture medium, and the other is the increased overall culture medium temperature from 35 degree C to 38 degree C for one hour each day (mild stress) or kept the retinal explants at 38 degree C constantly for five days (strong stress). In addition, the neural activity of retinal explants in these two stress conditions was examined using the multi-electrode array.
Results :
RGC neurite growth of retinal explants was significantly enhanced when the culture medium concentration was increased 1.25 folds, but not increased 1.5 folds. This suggests that mild stress of increased osmolarity could promore neurite outgrowth. Similarly, retinal explants grew longer neurites when the overall temperature was increased from 35 C to 38 C for one hour each day, 38 C but not when they were kept in constantly for five days. This also supports that mild stress of short-term increased temperature could enhance the RGC neurite outgrowth.
Conclusions :
The results demonstrate that the RGC axon regeneration under the mild stress condition is much efficient than under the control and strong stress conditions. This indicates that mild stress could promote the RGC neurite growth by turning the adverse circumstance to the favorable circumstance. These findings thus provide an insight into the cellular mechanism of retinal axon regeneration under the stress condition, which could potentially develop into a new method in neural regeneration.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.