Characterization of a prolonged regenerative attempt by diffusely injured axons following traumatic brain injury in adult cat: a light and electron microscopic immunocytochemical study
Characterization of a prolonged regenerative attempt by diffusely injured axons following traumatic brain injury in adult cat: a light and electron microscopic immunocytochemical study
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DOI：
10.1007/s004010050715
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发表时间：
1997-10-01
影响因子：
12.7
通讯作者：
Povlishock, JT
中科院分区：
文献类型：
--
作者：
Christman, CW;Salvant, JB;Povlishock, JT
众所周知，动物和人类的创伤性脑损伤会引起弥漫性分散在整个大脑的轴突损伤，而没有其他脑实质改变的证据。这一观察结果促使一些人假设，这些受损的轴突处于良好的位置，可以进行再生尝试。本研究使用神经突再生特异性免疫细胞化学标记来探讨这个问题。此外，为了加速和增强任何潜在的再生努力，本研究评估了鞘内应用神经生长因子的功效。在成年猫中进行了三组实验。一组动物遭受中度液体冲击脑损伤，损伤后随访7天或14天，植入渗透泵持续在脑室内灌注神经生长因子。将这些动物与第二组时间匹配、接受人工脑脊液输注的假手术动物进行比较。采用NR4单克隆抗体对低分子量神经丝亚基（NF-L）进行免疫组化染色评估轴突损伤。采用生长相关蛋白GAP43的免疫组化染色来定位表现再生反应的轴突。在假对照中，在光镜水平上，nf - l免疫反应性轴突肿胀在7天大量出现，但在损伤后14天，其频率明显下降。相比之下，gap43免疫反应性、断开的反应性轴突肿胀在第7天很少观察到，但在第14天大量观察到。在损伤后14天的超微结构分析中，仔细匹配的切片显示反应性轴突显示出与再生努力一致的发芽。对存活14天的动物组织的分析表明，补充神经生长因子似乎并没有增强受损脑轴突进行再生尝试的能力。相反，再生的努力似乎反映了一种自发的反应。第三组成年猫，受到同样的伤害，但没有进行渗透泵植入，被允许存活22-28天。该组动物在脑干反应性轴突肿胀中也表现出GAP43免疫反应性。这项研究表明，弥漫性损伤的轴突可以进行持续的再生尝试，这与细胞骨架的重组和生长相关蛋白的上调有关。
Traumatic brain injury in animals and humans is well known to cause axonal damage diffusely scattered throughout the brain without evidence of other brain parenchymal change. This observation has prompted some to posit that such damaged axons are well positioned to mount a regenerative attempt. The present study uses an immunocytochemical marker specific for regenerating neurites to explore this issue. Further, in an attempt to expedite and enhance any potential regenerative effort, this study evaluates the efficacy of intrathecally applied nerve growth factor. Three sets of experiments were performed in adult cats. One group of animals was subjected to moderate fluid percussion brain injury and followed for 7 or 14 days post injury, with the continuous intraventricular infusion of nerve growth factor delivered by implanted osmotic pumps. These animals were compared to a second group of time-matched, sham-operated animals receiving artificial cerebrospinal fluid infusion. To assess axonal damage immunohistochemical staining for the low molecular weight neurofilament subunit (NF-L) was carried out using an NR4 monoclonal antibody. To localize axons exhibiting a regenerative response immunohistochemical staining for the growth associated protein GAP43 was employed. In sham controls, at the light microscopic level NF-L-immunoreactive axonal swellings were numerous at 7 days, but by 14 days post injury their frequency declined markedly. In contrast, GAP43-immunoreactive, disconnected reactive axonal swellings were rarely observed at 7 days but were numerous at 14 days. Ultrastructural analysis at 14 days post injury of carefully matched sections revealed reactive axons demonstrating sprouting consistent with a regenerative effort. Analysis of tissue from animals of 14 days of survival indicated that supplementation with nerve growth factor did not appear to enhance the capacity of damaged brain axons to mount a regenerative attempt. Rather, it appears that regenerative efforts seen reflect a spontaneous response. A third group of adult cats, subjected to the same injury but not subjected to osmotic pump implantation was allowed to survive for 22-28 days. Animals in this group also demonstrated GAP43 immunoreactivity in reactive axonal swellings in the brain stem. This study demonstrates that diffusely injured axons can mount a sustained regenerative attempt that is associated with a reorganization of their cytoskeleton and accompanied by an up-regulation of growth-associated proteins.