Experimental Study On Treatment Of Traumatic Optic Nerve Injury With Caspase-3 Inhibitor In Rabbits By Immunohistochemistry

ObjectiveTo investigate the curative effect of Caspase-3 inhibitor on rabbits' traumatic optic nerve damages and actional mechanism.MethodsFifty-two rabbits with 2～3 months old were used in the study.They were randomly divided into experimental group(48) and normal control group(4). Normal rabbits were as normal control group.The model of rabbits' traumatic optic nerve damages was built by Fluid Percussion Brain Injury Device(FPI). In experimental groups,the left eyes of rabbits were as test control group, intravitreal injection with 2%DMSO 1μl;the right eyes of rabbits were as test cured group,intravitreal injection with Caspase-3 inhibitor z-DEVD-fmk 1μl. The flash visual evoked potential(F-VEP)was used to check the varience of the optic nerve injury by the time of 1,4,7,10,14,21 days after optic nerve injury.The retinal ganglion cells(RGCs) of eye tissues were observed by pathology.And the expressions of Caspase-3 in retina were detected by immunohistochemistry according to preceding time point.Results(1) F-VEPP₁₀₀:After optic nerve injury,compared with F-VEP of normal control group,the latency of F-VEPP₁₀₀ in experimental group rabbits prolonged significantly(P＜0.05).After cured the latency of F-VEPP₁₀₀ in test cured group was shorter than in test control group(F=27.713,P＜0.05).There was no statistical difference on the day 1,4(q=0.0518,P＞0.05).The statistical difference appeared 7 days after treatment(q=0.1294,P＜0.05).The difference was significant on day 14(q=0.1357,P＜0.05) and kept stable on day 21 (q=0.0568,P＞0.05).(2) Retinal histopathology(HE):After optic nerve injury,the number of RGCs became fewer and a great amount of RGCs without nucleus could be seen in both test cured group and test control group.These changes were more obvious in test control group than in test cured group.The differece between two groups was not significant on day 1 and 4 after treatment.On day 7,10,14 the difference was significant and it was more significant on day 14.The difference could be obtained to day 21.(3) Caspase-3:The expressions of Caspase-3 were detected in both test control group and test cured group.In test cured group the expressions of Caspase-3 were decreased(F=72.000,P＜0.05).After treatment there was no statistical difference on day 1,4(q=1.909,P＞0.05).The test indicators' statistical difference appeared on day 7(q=7.000,P＜0.05),reached the peak on day 14(q=11.909,P＜0.05) and kept stable on day 21(q=2.727,P＞0.05).Conclusion(1) The P₁₀₀ wave latency of F-VEP and the RGCs can evaluate the optic nerve function objectively.(2) Caspase-3 inhibitor is effective in treating rabbits' optic nerve damages. It can improve the recovery of nerve function.The effect appears at day 7 after treatment,reaches the peak on day 14 and keeps stable on day 21.(3) z-DEVD-fink can inhibit RGCs apoptosis effectively by blocking the function of Caspase-3 and protect the optic nerve after injury.