The Neuroprotective Effect of Intravitreally Injected CNTF on Rat Retinal Ganglion Cell in Optic Nerve Crush Injury Model

ABSTRACT

PURPOSE: To make an optic nerve crush injury model and to investigate the neuroprotective effect of intravitreally injected ciliary neurotrophic factor (CNTF) on rat retinal ganglion cells (RGCs) in the model. METHODS: The optic nerves of 12 Sprague-Dawley rats were crushed at 3 mm posterior to the eyeball for 1 minute using aneurysm clip (110 g). Two micrograms of CNTF in 2 micro liter of vehicle was injected intravitreally in one group (n=6) and 2 micro liter of PBS was injected in the control group (n=6) at 4, 7, and 10 days after the optic nerve injury. After 2 weeks, the retrograde labeling of the RGCs was done by the dextran tetramethylrhodamine. Twenty-four hours after the labeling, the retina was wholly mounted and the labeled RGCs were counted under the fluorescence microscope. RESULTS: The death of RGCs in this model began at 1 week and continued for 3 weeks. The number of labeled RGCs in CNTF-injected group (510+/-139/mm2) were significantly higher than that in control group (345+/-87/mm2)(p<0.05). CONCLUSIONS: The optic nerve crush injury model was established by use of aneurysm clip. In this model, the intravitreally injected CNTF had a neuroprotective effect on the rat RGCs.