【作者】 刘婉莹；

【导师】 鞠躬； 张卯年；

【作者基本信息】 第四军医大学 ， 神经生物学， 2004， 硕士

【摘要】 目的 利用一种规范化的大鼠视神经不完全损伤的动物模型，观察视神经切开减压(optic nerve incision decompressio,ONID)术后损伤的视通路在功能学、形态学及视神经损伤后的修复和再生等方面的变化，同时与单纯的视神经鞘膜减压术(optic nerve sheath fenestration or decompression,ONSD)进行对比，探讨该手术对不完全视神经损伤的保护作用及机制，从而判断视神经切开减压术的可行性及有效性，并掌握减压的最佳时机，为下一步的临床应用提供参考。 方法 1．观察不同程度视神经损伤及减压后闪光视觉诱发电位(flash-visual evoked potentials, F-VEP)的变化。通过对比减压组与对照组F-VEP潜伏期和振幅的变化，初步判断减压是否有效，并选择减压的最佳时机。 2．观察减压后视通路的形态学变化。通过光镜、电镜和荧光显微镜对ONID后视神经轴突及其胞体——视网膜神经节细胞(retinal 第四军医大学硕士学位论文 ganglion cen，RGC)的观察，反映视通路上各部位的形态、结构 及数量的变化，进一步验证切开减压对视神经不完全损伤的保护 作用。其中光镜包括视神经和视交叉的H.E染色及Luxol坚牢蓝 染色;透射电镜观察轴突形态及数目;荧光金逆行标记RGC进 行记数。3.观察ONID后视神经损伤的修复和再生情况。利用免疫组织化学 的方法，观察急性期巨噬细胞的聚集和细胞微管蛋白(Tubulin)Q 的表达;透射电镜观察再生结构。4.对比ONID与ONSD后F一VEP、神经结构、再生潜能的异同。结果1.F一vEP表明，ONID后，中度损伤组的减压眼较未减压眼峰潜时 提前，振幅增大;越早减压效果越好，48h减压就己基本无效。 ONID对轻、重度损伤后F一VEP的转归不理想。2.荧光金逆行标记中度损伤后，ONID组和对照组RGC计数结果表 明，ONID组RGC数目比对照组明显增多，下降速度明显减缓。3.视神经超微结构显示，ONID组髓鞘和轴突变性的程度明显小于 对照组。减压术后3个月视神经结构基本趋于稳定，即髓鞘结构 稳定，星型胶质细胞增生，无定形物质无增多:同时轴突的数目 不再继续下降，基本恒定。4.损伤后脱髓鞘现象普遍存在，视神经和视交叉中的大多有髓结构 受累。ONID组的脱髓鞘严重程度均比对照组明显减轻;视交叉 处细胞数目比对照组有明显增多，3个月后存活的细胞数基本 恒定，不再减少。5.ONID组损伤后3天至3周，于损伤中心可见巨噬细胞大量聚集， 1周时达高峰，有效清除损伤处神经组织的碎片和残骸，4周后 巨噬细胞才逐渐消失。对照组巨噬细胞的活动过程很短暂，这些 第四军医大学硕士学位论文 细胞聚集出现晚，随后很快消退，并且聚集的数目大大减少。6.ONID组Tubulin一。阳性，6个月时阳性结果最为明显。对照组 基本均为阴性。7.ONID组的视神经损伤区后可见大量丛状聚集、区域化分布的无 髓再生或芽生(sPouting)纤维，数目明显增多。8.ONSD对F一VEP的振幅的提高有一定作用，但对峰潜时的改善无 作用:ONSD组脱髓鞘的程度介于ONID组和对照组之间;髓鞘 和轴突变性程度较对照组在2个月内有减小，但3个月后视神经 结构的破坏程度没有停止，继续恶化;荧光金逆行标记RGC， ONSD组和对照组数目没有差异。ONSD组巨噬细胞数量明显少 于ONID组，2周时才见有细胞聚集，随后很快消失。结论1.ONID对中度视神经损伤后F一VEP的变化有一定改善作用，对轻 度和重度损伤却无益处。需尽早(48h内)进行减压有利减轻继 发性损伤。ONID对F一VEP的保护效果优于ONSD。2.ONID有效阻止继发性损伤对视神经结构的进一步破坏，明显延 缓了胞体的死亡速度及轴突的变性进程，对视神经结构起到了保 护作用，并且这种保护力度明显强于ONSD。3.oNID后各种利于中枢神经系统(eentral nervous system，eNs) 再生的因素表现较为活跃，例如某些炎性细胞和骨架蛋白。巨噬 细胞的活跃和微管蛋白的积极表达都提示我们，不论在短期还是 在长期，ONID都能使视神经表现出较强的自我修复能力和再生 潜能。更多还原

【Abstract】 With a calibrated animal model of incomplete optic nerve injury (ONI) in rats, the functional and morphological changes of the injured visual pathway, as well as optic nerve repair and regeneration after optic nerve incision decompression (ONID), were observed and compared with those after simple optic nerve sheath fenestration or decompression (ONSD). The function and mechanism of ONID of to protect optic nerve from injury were also investigated to evaluate the feasibility and availability of this new style surgical management, and to hold the optimal timing of decompression. Much reference for further clinical therapy of optic nerve injuries was wished to be able to be offered. Methods1. The latency and amplitude of F-VEP following ONI with ONID and without ONID were compared and analyzed to estimate the feasibility of ONID and to choose the most appropriate cases andoptimal operation timing.2. H.E. or Luxol Fast Blue staining, and transmission electron microscopy were used to observe the configuration and structure of optic nerve, retinal ganglion cells (RGC) and chiasma opticum. The numbers of RGCs retrograedly labeled by FluoroGold by fluoromicroscope were measured to evaluate the injury severity.3. Exploration on nerve repair and regeneration ability after ONID. The regeneration is observed by immunohistochemical detection of EDI and Tubulin- a in injured optic nerve tissues.4. The similarity and difference of F-VEP, microstructure and regeneration ability between ONID and ONSD were contrasted.Result1. After ONID, the latency of F-VEP in moderate optic nerve injury showed significant decrease and the amplitude showed significant increase. Within 48 hours, ONID group got better results. While after ONID on mild and severe groups, the latencies retarded, the amplitudes reduced.2. The number of RGCs in ONID group retrogradely labeled by FluoroGold is more than that in non-ONID group. The declining trend of non-ONID group consisted of an acute loss phase within two weeks after injury and an ensued slowly loss phase lasting months. While The declining trend of ONID group is not obvious, sliding smoothly.3. The degeneration of myelin sheath and axons in non-ONID group was severe, while it alleviated evidently in ONID group. The structure of optic nerve basically tends to stabilize in 3 months afterONID, namely stabilized myelin sheath, proliferated astrocytes, reduced amorphous substance, and non-decreasing axons.4. Demyelination of optic nerve following ONI alleviated and the cell number in chiasma opticum increased after ONID compared with non-ONID group. The cells remained stable after 3 months.5. A large number of EDI-positive macrophages infiltrated into the degenerating optic nerve following ONI ranging from 3days to 3weeks after ONID to clear the fragments and debris of degenerating myelin. These cells accumulate and reached a peak level by the 7th day following injury, and than cease in 4 weeks. EDI-positive macrophages in non-ONID group is just a transient presence, accumulating lesser, infiltrating later, subsequently disappearing earlier.6. Tubulin- a was expressed positively in optic nerve after ONID, and with a peak in 6 month. However, it was negative in non-ONID group.7. After ONID, there are many clustered, regional distributed bundles of putative unmyelinated regenerating or spouting axons in post-injury region.8. The amplitude of F-VEP after ONSD is augmented, but latency of F-VEP is not improved, still prolonged, even extinguishes.Conclusions1. F-VEP of moderate optic nerve injuries can be obviously improved after ONID, but the effects of ONID on mild and severe groups were less, even negative. It is useful only within 48 hours after injury to reduce secondary optic nerve injury. The ONID protectiveeffect on F-VEP is superior to ONSD.2. ONSD prevents optic nerve structure from secondary injury. It reduces the d更多还原