Abstract
Purpose :
Optic nerve injury is a primary cause of the death of retinal ganglion cells (RGCs) and increasing evidence suggests that RGCs are susceptible to various injuries in a type specific manner.However, the type specific vulnerability of RGCs to optic nerve injury and other types of injuries has not been fully characterized.We hypothesize that the susceptibility of RGCs to optic nerve injury varies among different types of RGCs and we characterized the susceptibility of several genetically identified RGC types to optic nerve injury and compared the results with that induced by N-methyl-D-aspartate (NMDA) excitotoxicity.
Methods :
Four transgenic mouse lines provided 4 groups (8 types) YFP-expressing RGCs for this study. The optic nerve crush (ONC) was performed unilaterally on all mice around the age of P90 using a cross-action forceps under and anesthenia with 2-5% isoflurane and a local application of 0.5% proparacaine hydrochloride. One eye of each mouse was treated with ONC and the contralateral eye was used as a control. Both ONC treated and the control eyes were enucleated at 3, 5, 7, 14, 30 and 60-90 days after surgery. The retinas were isolated and fixed with 4% PFA. Fluorescent signals of YFP-expressing RGCs was enhanced by antibody staining, the total RGCs were labeled with an anti-RBPMS antibody, and the retinas were flat-mount for confocal microscopy. The number of YFP-expressing RGCs and the total RGCs of ONC treated eyes were measured and compared to the control eyes to calculate the survival rate. Two-tailed Student's t-test and X2test were used for statistical analysis.
Results :
The susceptibility of different types of RGCs to ONC varies significantly, in which the BD-RGCs are the most resistant type of RGCs while theW3-RGCs and J-RGCs are the most sensitive cells to ONC.The survival rates 7 days after ONC of BD-RGCs, αRGCs, J-RGCs and W3-RGCs are 58.9±5.9% (n=10), 53.7±2.7% (n=10), 31.9±4.4% (n=8), 25.9±1.9% (n=9), respectively (p < 0.001). In addition, the survival rates of BD-RGCs and J-RGCs after ONC are significantly different from that of RGC death induced by NMDA excitotoxicity.
Conclusions :
Our results are consistent with our hypothesis that the susceptibility of RGCs to ONCvaries among different types of RGCs in a type specific manner. In addition, the susceptibility of the same types of RGCs to ONC and NMDA excitotoxicity are significantly different.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.