Experimental Study On Establishment Of Traumatic Optic Neuropathy Animal Model And Treatment Of It

1. The Establishment of Traumatic Optic Neuropathy Animal Model in Rabbits Using FPIObjective To establish an animal model of traumatic optic neuropathy(TON) using fluid percussion brain injury device(FPI). Methods Animal model of TON was established using FPI. The changes of morphology and F-VEP were observed at different observing time points before and after injury. Results (1) In control group, the retina and choroid were well structured, and RGCs was monolayer, intensive, and arranged well, the nuclear was clear, nuclear membranes was smooth and intact. But in experimental groups, with the time went on after injury, every layer of the retina became thin and the numbers of cells became small. Karyopyknosis was seen in RGCs, and plenty of RGCs with cavitation appeared.(2) F-VEP of rabbits in control group showed the typical N75-P100-N135contours and the latency and amplitudes of P100waves were (41.63±4.89)ms and (9.12±2.97)μv respectively. And in experimental groups, at1day after injury, N-P100-N waves were low and flat, with lengthened latency and reduced amplitudes of P100waves. The differences of parameters between control group and experimental groups were statistically significant. Conclusion TON animal model was successfully established using FPI, and made a good foundation for the correlational studies of pathogenesis of TON. 2. Experimental Study on the Role of Lens Injury in Axonal Regeneration of RGCs in Traumatic Optic Nerve NeuropathyObjective To explore the role of lens injury in the repair mechanism of traumatic optic neuropathy(TON) in an animal model. Methods128healthy Chinese white rabbits were divided into two groups randomly, experimental and control groups. According to the different observing time points(1,4,7,10,14,21and28days), each group was further divided into seven subgroups, each subgroup had eight rabbits. TON animal model was made using fluid percussion brain injury device (FPI) in right eye of each rabbit, in experimental group, lens injury was made in right eye of each rabbit, and in control group, lens injury was not made in right eye of each rabbit. F-VEP was recorded and analysed in above time points. Experimental animals were sacrificed in above time points for the histopathological examination. Macrophageswere labeled by ED-1antibody and survival retinal ganglion cells (RGCs) were stained by Nissl method. Results In experimental group,1day after injury, the P100latency of F-VEP increased and the P100amplitude reduced significantly, the P100latency reached the longest at10days after injury, and then shortened gradually, the P100amplitude reached the lowest at7days after injury, and then recovered gradually. In control groups, the P100latency increased and the P100amplitude decreased gradually. In experimental group, the histopathological examination showed activated macrophages stained by Nissl method were detected in the retina at4day after injury, retinal ganglion cell axon regeneration was detected at7day after the injury. However, in control group, activated macrophages stained by Nissl method and retinal ganglion cell axon regeneration were not detected in retina at all the observing time points. Conclusions Lens injury could promote axonal regeneration of RGCs in traumatic optic neuropathy animal model, and activated macrophages may play an important role in this recovery process. 3. The Protective Effect of Z-DEVD-FMK on RGCs in Rabbits Traumatic Optic Neuropathy Animal ModelObjective:To investigate the protective effect of Z-DEVD-FMK on RGCs in rabbits traumatic optic neuropathy animal model. Methods:Experimental group was sub-devided into intravitreous injection group and peribulbar injection group with48rabbits in each group, the right eye of each rabbit in intravitreous injection group was injected with caspase-3inhibitor Z-DEVD-FMK (A group), left eye was intravitreously injected with DMSO (B group). The right eye of each rabbit in peribulbar injection group was injected with caspase-3inhibitor Z-DEVD-FMK (C group), the left eye was injected with DMSO (D group). The rest8rabbits were as normal control group. The experiment group was divided into6sub-groups by the different observing time points such as1,4,7,10,14,21days after injury with8rats in each groups. The animal model of traumatic optic neuropathy in rabbits was made by fluid percussion brain injury device (FPI). Z-DEVD-FMK was used30minutes after the establishment of traumatic optic neuropathy animal model. Flash-visual evoked potential (F-VEP) was used to check the changes of visual function and TUNEL to detect the apoptosis of retinal ganglion cells. Results:(1) F-VEP results:Compared to rabbits in the control group, the latency of F-VEP in experimental group gradually increased7,10,14,21days after injury, there was statistical significance compared to the control group (P<0.05). The latency of F-VEP in experiment group was still prolonged4days after injury, and was statistically significant compared to that of the control group (P<0.05). The latency and amplitude of group A21days after injury were(64.46±5.92)ms and(6.61±2.61)μv, that of group C were(71.06±.57)ms and(5.91±1.64)μv respectively, and there was statistical significance compared to group C (P<0.05).(2) TUNEL results:The apoptosis of RGCs could be observed1day after injury, increased at the4th day, and reached to a climax at7day after injury in control group. The maniple apoptosis of RGCs were found at4-10days after injury in experiment group. And the rate of apoptosis in RGCs was decreased significantly compared to control group at4-21days after injury(P<0.05). Conclusion:The Caspase-3inhibitor Z-DEVD-FMK lasted longer than the effect of peribulbar injection.