MYELINATED FIBER REGENERATION AFTER CRUSH INJURY IS RETARDED IN SCIATIC-NERVES OF AGING MICE
MYELINATED FIBER REGENERATION AFTER CRUSH INJURY IS RETARDED IN SCIATIC-NERVES OF AGING MICE
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DOI：
10.1002/cne.903080205
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发表时间：
1991-06-08
影响因子：
2.5
通讯作者：
WEBSTER, HD
中科院分区：
文献类型：
--
作者：
TANAKA, K;WEBSTER, HD
为了比较年轻成年小鼠和老年小鼠的神经再生，6个月和24个月大的小鼠的右侧坐骨神经在坐骨神经切口处被挤压。两周后，两组小鼠均灌流乙醛溶液，在附加固定后，对坐骨神经进行处理，以使随后通过光镜和电子显微镜观察的每条神经的横断面包括挤压部位远端5 mm处的整个胫后神经束。在未手术的对侧神经中切开相同的水平；这些神经作为对照。用电子显微镜和BioQuant图像分析系统IV测量胫骨后束的面积，计数有髓轴突和无髓轴突的数目及其在雪旺细胞单元中的出现频率。在老年小鼠中，再生有髓轴突的总数显著减少，但在老年和年轻人中再生的无髓轴突总数没有显著差异。在衰老小鼠中，含有单个无髓轴突的雪旺细胞的频率更高，这表明在髓鞘形成之前，雪旺细胞对轴突的包膜也减慢了。挤压伤致神经切断后，胫骨后束面积小于青壮年，髓鞘残留物的远端解体也明显延缓。结果表明，神经元、轴突和雪旺细胞的反应可能是减缓衰老小鼠坐骨神经中有髓纤维再生的重要因素。
To compare nerve regeneration in young adult and aging mice, the right sciatic nerves of 6- and 24-month-old mice were crushed at the sciatic notch. Two weeks later, both groups of mice were perfused with an aldehyde solution, and, after additional fixation, the sciatic nerves were processed so that the transverse sections of each nerve subsequently studied by light and electron microscopy included the entire posterior tibial fascicle 5 mm distal to the crush site. The same level was sectioned in unoperated contralateral nerves; these nerves served as controls. Electron micrographs and the Bioquant Image Analysis System IV were used to measure areas of posterior tibial fascicles and count the number of myelinated axons, the number of unmyelinated axons, and their frequency in Schwann cell units. In aging mice, the total number of regenerating myelinated axons was significantly reduced, but totals of regenerating unmyelinated axons in aging and young adults did not differ significantly. In aging mice, the frequency of Schwann cells that contained a single unmyelinated axon was greater, suggesting that before myelination began, Schwann cell ensheathment of axons also was slowed. After axotomy by a crush injury, the area of the posterior tibial fascicle was less than that in young adults and the distal disintegration of myelin sheath remnants also appeared to be retarded. The results indicate that responses of neurons, axons, and Schwann cells could be important in slowing the regeneration of myelinated fibers found in sciatic nerves from aging mice.