Himes B T, Goldberger M E, Tessler A
Department of Anatomy and Neurobiology, Medical College of Pennsylvania, Philadelphia 19129.
J Comp Neurol. 1994 Jan 1;339(1):117-31. doi: 10.1002/cne.903390111.
Many conditions are thought to contribute to neuron death after axotomy, including immaturity of the cell at the time of injury, inability to reestablish or maintain target contact, and dependence on trophic factors produced by targets. Exogenous application of neurotrophic factors and transplants of peripheral nerve and embryonic central nervous system (CNS) tissue temporarily rescue axotomized CNS neurons, but permanent rescue may require transplants that are normal targets of the injured neurons. We examined the requirements for survival of axotomized Clarke's nucleus (CN) neurons. Two months after hemisection of the spinal cord at the T8 segment, there was an ipsilateral 30% loss of neurons at the L1 segment in adult operates and a 40% loss in neonates. Transplants of embryonic spinal cord, cerebellum, and neocortex inserted into the T8 segment at the time of hemisection prevented virtually all of the cell death in both adults and neonates, but transplants of embryonic striatum were ineffective. None of the grafts prevented the somal atrophy of CN neurons caused by axotomy. Retrograde transport of fluoro-gold from the cerebellum demonstrated that 33% of all CN neurons at L1 project to the cerebellum, 50% of these died following a T8 hemisection, but all these projection neurons were rescued by a transplant of embryonic spinal cord. These results suggest that the rescue of axotomized CN neurons is relatively specific for the normal target areas of these neurons, but this specificity is not absolute and may depend on the distribution and synthesis of particular neurotrophic agents.
许多情况被认为会导致轴突切断后神经元死亡，包括损伤时细胞的不成熟、无法重新建立或维持与靶标的接触以及对靶标产生的营养因子的依赖。外源性应用神经营养因子以及外周神经和胚胎中枢神经系统（CNS）组织移植可暂时挽救被轴突切断的CNS神经元，但永久性挽救可能需要移植成为受损神经元正常靶标的组织。我们研究了被轴突切断的克拉克核（CN）神经元存活的条件。在T8节段脊髓半横切术后两个月，成年手术动物L1节段同侧神经元损失30%，新生动物损失40%。在半横切时将胚胎脊髓、小脑和新皮质移植到T8节段，几乎可防止成年和新生动物的所有细胞死亡，但胚胎纹状体移植无效。没有一种移植能防止轴突切断引起的CN神经元胞体萎缩。从小脑逆行运输氟金显示，L1节段所有CN神经元中有33%投射到小脑，其中50%在T8半横切后死亡，但所有这些投射神经元都通过胚胎脊髓移植得到了挽救。这些结果表明，被轴突切断的CN神经元的挽救对这些神经元的正常靶标区域具有相对特异性，但这种特异性并非绝对，可能取决于特定神经营养因子的分布和合成。
