Abstract
Purpose :
The overall purpose of this project is to investigate the effect of optogenetic stimulation on retinal ganglion cell (RGC) protection and axonal regeneration after optic nerve crush.
Methods :
Thy1-Chr2-EYFP mice were separated into control and stimulated environment at different time points after optic nerve crush. The mice in stimulated group received blue light stimulation at 1HZ while the control mice were kept in normal 12h light/dark cycle. To follow the change of retinal ganglion cell (RGC) number longitudinally, confocal laser scanning ophthalmoscopy images were taken at 7 days before crush and 7 days, 28 days after crush. One month after crush, mice were sacrificed and prepared for optic nerve cross section staining and retinal wholemount staining. Based on the staining results, RGCs survival rate and axonal regeneration length were quantified. Mice retinal ganglion cell function was measured by customized pattern electroretinogram (PERG) at 7 days before crush and 7 days, 28 days after crush. The peak amplitude of PERG was used to represent RGC function.
Results :
Optogenetic stimulation increases RGCs survival rate after damage. The ratio of live/functional RGCs and dead/dysfunctional RGCs in stimulated group (n=3) is significantly greater (p<0.05) than that of control group (n=3). Optogenetic stimulation promotes axonal regeneration after crush. The mice in stimulated group (n=13) have significantly larger (p<0.01) number of axons that can extend beyond the crush site and they can run significant (p<0.01) longer distance compared to the control group (n=9). Optogenetic stimulation promotes RGCs function recovery after damage. The mice received optogenetic stimulation (n=4) for one month after crush showed normal pattern electroretinogram (PERG) wave and the peak amplitude is significantly (n<0.05) increased compared to the PERG recording at 7 days after crush. However, there is no difference of PERG peak amplitude between PERG recording at 7 days and 28 days after crush in mice without optogenetic stimulation (n=4).
Conclusions :
In our present study, the optogenetic stimulation does increase RGC survival rate after optic nerve crush. Additionally, mice in optogenetically stimulated group show a larger portion of axons that can extend beyond the crush site and run longer distance. Surprisingly, we even observe retinal ganglion cell function recovery after optogenetic stimulation.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.