| Objective:(1)Using FPI to found a standard animal model of traumatic optic nerve injury of rabbits and explore the stability of the model.(2)To evaluate quantitatively the treatment of traumatic optic nerve injury rabbit with caspase-3 inhibitor z-DEVD-fmk,and analyze related factors.(3)To detect the protection of visual function by caspase-3 inhibitor z-DEVD-fmk after optic nerve crush in rabbits,and to provide the new way of therapy for patients of optic nerve crush in clinic.Methods:One hundred and forty-eight healthy chinese white rabbits were used in this study. Four rabbits(8 eyes) were randomly selected as a normal control group,the remaining 144(288 eyes) for the experimental groups.In experiment groups 144 Chinese rabbits were randomly divided into low-dose group(L group,1.5μg/kg,48), middle-dose group(M group,2.5μg/kg,48) and high-dose group(H group,3.5μg/kg 48) by different administration dosage,each experiment group was divided into 6 sub-groups by the time of 1,4,7,10,14,21 days after injury with 8 rats in each group.Take self-control method,that is,the unilateral eye was made as the traumatic optic nerve injury model,right eyes were treated eyes,and left eyes were control eyes. The standardized animal models of traumatic optic nerve injury were built with FPI (Fluid Percussion Brain Injury Device).The treated eye was injected in vitreous cavity with caspase-3 inhibitor 30 minutes after injury.As a control,the control eye of each rabbit was injected into the same dose dimethyl sulfoxide(DMSO).All eyes were examined by flash visual evoked potential(F-VEP),HE staining,the numerical count of survivor retinal ganglion cells and Western blot analysis to detected caspase-3 protein expression.Results:(1)The expression of caspase-3:The expression and activation of caspase-3 after traumatic optic nerve injury can be inhibited effectively by caspase-3 inhibitor z-DEVD-fmk.The specific bands of caspase-3 precursor(32kDa) and the cut fragment(12kDa) can be found in both treatment eyes and control eyes of rabbit retinal tissues.The expression of caspase-3 precursor and the cutting fragment were obvious high in the retina of the control eye;caspase-3 precursor expressed at low levels in treated eyes.Whether be treated of not,the relationship between amount of caspase-3 precursor and its cutting fragment and time was not appeared obviously.(2)Retinal histopathology:In the normal controls,each layer of the retina was arranged orderly and densely under light microscope.In experiment groups,1 day after injury,ruptured capillary could be seen in ganglion cell layer(GCL),21 days after injury,cells in each layer arranged sparsely and disorderedly,in some RGCs chromatin became densely,the number of cells in every layer became fewer,large amount of RGCs without nucleus could be seen,the thickness of the whole retina became thin.RGCs ratio increased gradually with the administration duration extended in both middle-dose group and high-dose group(P＜0.01);RGCs ratio in both middle-dose group and high-dose group were significantly higher than the low-group 10 days after treatment(P＜0.01).(3)F-VEP:Steady N-P100-N wave was reliably displayed with latency of 42.72+/-2.74ms and amplitude of 8.79+/-2.12μv in the rabbits before injury.After injury,control eyes in middle-dose group:1 day after injury the latency prolonged to 86.90+/-7.71ms and the amplitude decreased to 5.29+/-1.06μv,the changes of the latency and the amplitude compared with the values before injury were significant (P＜0.05).Three experimental groups showed deterioration 1 day and 4 days after treatment,but from the 7th day the latency and amplitude were both recovery.With the time of administration prolonged,the latency shortened and amplitude increased in low-dose group,middle-dose group and high-dose group(P＜0.01).Conclusion:(1)A standard animal model of optic nerve injury of rabbits can be successfully founded using FPI.(2)Caspase-3 inhibitor z-DEVD-fmk inhibits RGCs apoptosis effectively by blocking the adoption of caspase-3 to reach the neuroprotective effect.(3)The protective effect of visual function with z-DEVD-fmk appeared 7 days after treatment and kept stable on day 21.
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