CHARACTERIZATION OF THE SPROUTING RESPONSE OF AXON-LIKE PROCESSES FROM RETINAL GANGLION-CELLS AFTER AXOTOMY IN ADULT HAMSTERS - A MODEL USING INTRAVITREAL IMPLANTATION OF A PERIPHERAL-NERVE
CHARACTERIZATION OF THE SPROUTING RESPONSE OF AXON-LIKE PROCESSES FROM RETINAL GANGLION-CELLS AFTER AXOTOMY IN ADULT HAMSTERS - A MODEL USING INTRAVITREAL IMPLANTATION OF A PERIPHERAL-NERVE
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DOI：
10.1007/bf01187119
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发表时间：
1992-08-01
期刊：
影响因子：
--
通讯作者：
SO, KF
中科院分区：
文献类型：
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作者：
CHO, EYP;SO, KF
周围神经为受损的CNS轴突发芽和再生提供了有利的环境。也已经证明，视网膜神经节细胞通过从体树突隔室发射轴突样突起到移植物中来响应移植到视网膜的外周神经节段。在这项研究中，通过将不与视网膜接触的短段周围神经植入到视神经同时被压碎的眼睛的玻璃体中，探讨了影响轴突切断的视网膜神经节细胞发芽模式的因素。银染色用于评估经历出芽的视网膜神经节细胞的形态。一些视网膜神经节细胞被诱导出芽轴突样突起;这些突起主要从树突出现，较少从索马或视网膜内轴突出现。植入无活力的移植物（冻融）仅引起极轻微的发芽。这些结果表明，在移植物中的细胞分泌的扩散因子是一个可能的刺激发芽在axotomized retinal ganglion cells.Examination的树突状细胞发芽的模式表明，发芽是最强烈的（在芽数每细胞）在早期post-axotomy。此外，从同一个细胞的单个初级树突所产生的芽的发展的差异模式进行了观察;芽往往会出现从所有初级树突最初，但随着轴突切断术后的时间增加，从一些初级树突芽的回缩发生。伴随着这种收缩，然而，有一个芽的数量增加，这些初级树突仍处于活跃阶段的发芽。外部因素对芽苗菜的选择性稳定可能是造成这一现象的原因。视神经损伤后2周至2个月内有出芽的视网膜神经节细胞胞体的形态（不规则性）与树突树出芽的强度在时间上相关，表明在出芽过程中，内在机制协调不同细胞区室的反应。与玻璃体内移植物存在下轴突切断的视网膜神经节细胞的广泛异位发芽相反，当将长的外周神经段移植到切割的视神经上时，存在从视网膜神经节细胞进入移植物的广泛轴突再生，其中大多数没有表现出异位发芽。因此，神经元内的发芽位点似乎存在层次结构，受损的轴突尖端是最受欢迎的位点，其次是树突，然后是视网膜内轴突。索马似乎是最不喜欢的隔间芽排放。
Peripheral nerves provide a favourable environment for damaged CNS axons to sprout and regenerate. It has also been demonstrated that retinal ganglion cells respond to a peripheral nerve segment grafted to the retina by emitting axon-like processes from the somatodendritic compartment into the graft. The factors influencing the pattern of sprouting of axotomized retinal ganglion cells were explored in this study by implanting a short segment of peripheral nerve, which did not come into contact with the retina, into the vitreous body of an eye whose optic nerve was concurrently crushed. Silver staining was used to assess the morphology of the retinal ganglion cells which underwent sprouting.Some retinal ganglion cells were induced to sprout axon-like processes; these emerged primarily from dendrites and less frequently from the soma or intraretinal axon. Implantation of a nonviable graft (freezed-thawed) elicited only minimal sprouting. These results suggest that diffusible factors secreted by cells in the graft are a possible stimulus to sprouting in axotomized retinal ganglion cells.Examination of the pattern of dendritic sprouting indicates that sprouting was most intense (in terms of number of sprouts per cell) at early times post-axotomy. Moreover, a differential pattern of development of sprouts arising from individual primary dendrites of the same cell was observed; sprouts tend to arise from all primary dendrites initially but as the post-axotomy time increased, retraction of sprouts from some primary dendrites occurred. Concomitant with this retraction, however, there was an increase in the number of sprouts on those primary dendrites which were still in the active phase of sprouting. Selective stabilization of sprouts by extrinsic factors may account for this phenomenon.Changes in the area and outline (irregularity) of the somata of retinal ganglion cells with sprouts from two weeks to two months after optic nerve crush could be correlated temporally with the intensity of sprouting from the dendritic tree, suggesting that during sprouting, intrinsic mechanisms coordinate the responses of different cellular compartments.In contrast to extensive ectopic sprouting of axotomized retinal ganglion cells in the presence of an intravitreal graft, when a long peripheral nerve segment is grafted to the cut optic nerve, there is extensive axonal regeneration into the graft from retinal ganglion cells, most of which did not exhibit ectopic sprouting. Thus, a hierarchy of sprouting sites within a neuron seems to exist, with the damaged axonal tip being the most favoured site, followed by the dendrites, and then the intraretinal axon. The soma appears to be the least preferred compartment for sprout emission.