Recent evidence suggests that ≃ 90% of retinal ganglion cells (RGCs) die by the process of apoptosis within 14 days of optic nerve transection. RGCs begin to disappear from the retina between 5 and 7 days postaxotomy when the highest percentage of RGCs show characteristics typical of apoptosis. A single intraocular injection of glial cell-line derived neurotrophic factor (GDNF) given at the time of axotomy resulted in a delay in the initiation of RGC death and increased the densities of surviving RGCs at 7, 10 and 14 days postaxotomy. The mean RGC densities in GDNF treated retinas at 7 (2381 ± 144), 10 (1561 ± 117) and 14 (1123 ± 116) days postaxotomy were significantly higher than that of controls (1835 ± 82, 835 ± 272 and 485 ± 39, respectively). The loss of RGCs was paralleled by increases in TUNEL positive staining in control retinas and a lower percentage of TUNEL positive cells in GDNF treated retinas at 5, 7 and 10 days postaxotomy. These results suggest that GDNF is capable of promoting RGC survival following injury, possibly by interfering with an essential step in apoptosis.
Koeberle, P. D., & Ball, A. K. (1998). Effects of GDNF on retinal ganglion cell survival following axotomy. In Vision Research (Vol. 38, pp. 1505–1515). https://doi.org/10.1016/S0042-6989(97)00364-7