A model to study differences between primary and secondary degeneration of retinal ganglion cells in rats by partial optic nerve transection
A model to study differences between primary and secondary degeneration of retinal ganglion cells in rats by partial optic nerve transection
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DOI：
10.1167/iovs.02-0646
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发表时间：
2003-08-01
影响因子：
4.4
通讯作者：
Valenta, DF
中科院分区：
文献类型：
--
作者：
Levkovitch-Verbin, H;Quigley, HA;Valenta, DF
目的.目的：建立大鼠视神经损伤模型，鉴别原发性和继发性视网膜神经节细胞（RGC）损伤。在全身麻醉下，用改良的金刚石刀横断白化病Wistar大鼠眶上级1/3视神经。通过在神经损伤前1周将荧光金染料逆行注入上级丘中的细胞数和视神经横截面中的轴突数来定量存活的RGC的数量。在56只大鼠中计数RGCs，每个视网膜整体计数中检查24个区域。在横断后4天、8天、4周和9周对大鼠进行研究。还比较了5只未接受手术的对照大鼠和5只接受单侧假手术的大鼠的视网膜节细胞的眼间差异。经组织学证实，只有上视神经直接受损。在损伤后第4天和第8天，上级RGC与其对侧眼的平均差异分别为-30.3%和62.8%（P = 0.02和0.001，t检验，n = 8只大鼠/组），而假手术眼没有显著损失（眼间平均差异= 1.7%，P = 0.74，t检验）。第8天时，下RGC与对照对侧眼相比无变化（平均眼间差异=-4.8%，P = 0.16，t检验）。切断后9周，下RGC比其对侧眼减少34.5%，相比之下，与对侧眼相比，受损眼的上级区域的RGC减少41.2%。对视神经中RGC轴突的拓扑结构的详细连续切片研究表明，纤维的有序排列与其在视网膜中的细胞体位置相关。大鼠部分视神经切断模型显示，上级视网膜中直接损伤的RGC迅速丧失，而在其轴突未被切断的下部视网膜中RGC延迟但显著的继发性丧失。这些发现证实了在猴眼中的类似结果，并提供了一种啮齿动物模型，其中可以测试针对继发性变性的药物干预。
PURPOSE. To use a rat model of optic nerve injury to differentiate primary and secondary retinal ganglion cell (RGC) injury.METHODS. Under general anesthesia, a modified diamond knife was used to transect the superior one third of the orbital optic nerve in albino Wistar rats. The number of surviving RGC was quantified by counting both the number of cells retrogradely filled with fluorescent gold dye injected into the superior colliculus 1 week before nerve injury and the number of axons in optic nerve cross sections. RGCs were counted in 56 rats, with 24 regions examined in each retinal wholemount. Rats were studied at 4 days, 8 days, 4 weeks, and 9 weeks after transection. The interocular difference in RGCs was also compared in five control rats that underwent no surgery and in five rats who underwent a unilateral sham operation. It was confirmed histologically that only the upper optic nerve had been directly injured.RESULTS. At 4 and 8 days after injury, superior RGCs showed a mean difference from their fellow eyes of -30.3% and -62.8%, respectively (P = 0.02 and 0.001, t-test, n = 8 rats/group), whereas sham-operation eyes had no significant loss (mean difference between eyes = 1.7%, P = 0.74, t-test). At 8 days, inferior RGCs were unchanged from control, fellow eyes (mean interocular difference = -4.8%, P = 0.16, t-test). Nine weeks after transection, inferior RGC had 34.5% fewer RGCs than their fellow eyes, compared with 41.2% fewer RGCs in the superior zones of the injured eyes compared with fellow eyes. Detailed, serial section studies of the topography of RGC axons in the optic nerve showed an orderly arrangement of fibers that were segregated in relation to the position of their cell bodies in the retina.CONCLUSIONS. A model of partial optic nerve transection in rats showed rapid loss of directly injured RGCs in the superior retina and delayed, but significant secondary loss of RGCs in the inferior retina, whose axons were not severed. The findings confirm similar results in monkey eyes and provide a rodent model in which pharmacologic interventions against secondary degeneration can be tested.