Slater Bernard J, Mehrabian Zara, Guo Yan, Hunter Allan, Bernstein Steven L
Department of Ophthalmology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
Invest Ophthalmol Vis Sci. 2008 Aug;49(8):3671-6. doi: 10.1167/iovs.07-0504.
Nonarteritic anterior ischemic optic neuropathy (NAION) results in optic nerve damage with retinal ganglion cell (RGC) loss. An NAION model, rodent anterior ischemic optic neuropathy (rAION), was used to determine AION-associated mechanisms of RGC death and associated regional retinal changes.
rAION was induced in male Wistar rats, and the retinas analyzed at various times after induction. RGCs were positively identified by both retrograde fluorogold labeling and brain-expressed X-linked protein-1/2 (Bex1/2) immunoreactivity. RGC death was analyzed by fluorescein-tagged annexin-V labeling (FITC-annexin-V), as well as by terminal nucleotide nick-end labeling (TUNEL). Retinal flatmount preparations enabled regional retinal analysis of labeled dying cells. Apoptosis pathway activation was confirmed by Western analysis, with an antibody that recognizes cleaved caspase-3.
Post-rAION, RGCs die by apoptosis over a longer period than previously recognized. Cleaved caspase-3 immunoreactivity was greatest between 11 and 15 days. rAION-induced RGC death occurs regionally, with sparing of large contiguous regions of RGCs.
rAION results in later RGC death than in traumatic optic nerve damage models. Apoptosis, measured by FITC-annexin, occurs maximally in the second to third week after infarct. Cleaved caspase-3 activation confirms that after rAION, RGCs undergo apoptosis by the caspase activation pathway. The regional pattern in dying RGCs after rAION implies that a measure of retinotopic organization occurs in the rodent optic nerve. The prolonged period from insult to death suggests that the window for successful treatment after ON infarct may be longer than previously recognized.
非动脉炎性前部缺血性视神经病变（NAION）会导致视神经损伤并伴有视网膜神经节细胞（RGC）丢失。采用一种NAION模型，即啮齿动物前部缺血性视神经病变（rAION），来确定与AION相关的RGC死亡机制以及视网膜相关区域的变化。
在雄性Wistar大鼠中诱导产生rAION，并在诱导后的不同时间对视网膜进行分析。通过逆行荧光金标记和脑表达X连锁蛋白1/2（Bex1/2）免疫反应性来阳性鉴定RGC。通过荧光素标记的膜联蛋白-V标记（FITC-膜联蛋白-V）以及末端核苷酸缺口末端标记（TUNEL）来分析RGC死亡情况。视网膜平铺标本可对标记的死亡细胞进行视网膜区域分析。通过蛋白质免疫印迹分析，使用识别裂解的半胱天冬酶-3的抗体来确认凋亡途径的激活。
rAION后，RGC通过凋亡死亡的时间比之前认为的更长。裂解的半胱天冬酶-3免疫反应性在第11至15天最强。rAION诱导的RGC死亡呈区域性发生，大片连续的RGC区域未受影响。
与创伤性视神经损伤模型相比，rAION导致RGC死亡的时间更晚。通过FITC-膜联蛋白检测到的凋亡在梗死发生后的第二至三周达到最大程度。裂解的半胱天冬酶-3的激活证实，rAION后RGC通过半胱天冬酶激活途径发生凋亡。rAION后死亡RGC的区域模式表明啮齿动物视神经中存在一定程度的视网膜拓扑组织。从损伤到死亡的时间延长表明，视神经梗死之后成功治疗的窗口期可能比之前认为的更长。
