神经节苷脂预防华勒变性的显微结构研究

A morphological study on the occurrence of wallerian degeneration of rat sciatic nerves after nerve cutting and preventive effect of gangliosides

目的：观察预防性给予神经节苷脂对神经切断后神经纤维变性的预防作用。方法：连续８ｄ给大鼠ｉｐ２０和５０ｍｇ·ｋｇ－１·ｄ－１神经节苷脂，ｄ９将大鼠坐骨神经切断，切断后分别于ｄ７和ｄ１１用图像分析仪检查该神经远段内有髓神经纤维变性情况。结果：５０ｍｇ·ｋｇ－１组坐骨神经内完整髓鞘的有髓神经纤维数目于ｄ７和ｄ１１分别比２０ｍｇ·ｋｇ－１组多。而且５０ｍｇ·ｋｇ－１和２０ｍｇ·ｋｇ－１２组完整髓鞘的有髓神经纤维数目于ｄ７均比于ｄ１１多。而两个生理盐水对照组（ｄ７和ｄ１１）内神经纤维普遍崩解，以上各组中的有髓神经纤维轴突直径和神经纤维直径以及它们之间的比值与正常有髓神经纤维相似（Ｐ＞０．０５）。而正常大鼠坐骨神经挫伤后ｄ１５观察发现其内的再生有髓神经纤维的轴突直径和神经纤维直径均较大，约为正常有髓神经纤维的２倍，比值则较小（Ｐ＜０．０５）。结论：大鼠神经损伤前预防性给予的神经节苷脂能防止神经纤维华勒氏变性，而不是促进变性的神经纤维再生。同时也说明，神经损伤之前机体内储存足量神经节苷脂在程度和时间上对于预防神经华勒氏变性是有益的。

AIM: To observe the preventive effect of pretreated gangliosides on the occurrence of wallerian degeneration of rat sciatic nerves after nerve cutting. METHODS: Rats were treated intraperitonealy with 20 and 50 mg·kg -1 ·d -1 of a ganglioside mixture respectively for 8 d, then the sciatic nerve of the rats was cut. In the d 7 and d 11 after nerve cutting, histological evaluation of the sciatic nerve transverse sections 1 cm distal to the cutting site was performed by means of a image analyzer, and the number of nerve fibbers, axon diameter, fibber diameter and their ratio determined. In nerve fibber regeneration group sciatic nerve was crushed using a standardized procedure, in d 15 transverse sections 1 cm distal to the crushing site were analyzed using the same methods. RESULTS: We found that there are nerve fibbers in all gangliosides pretreated groups, and all fibbers in the control group (physiological saline treated) disintegrated. The axon diameter, fibber diameter and their ratio of the above groups are similar to normal nerve fibbers( P >0 05). In the nerve fibber regeneration group, the axon diameter and fibber diameter are greater than normal fibbers( P <0 001). Their ratio is smaller than normal fibbers( P <0 05). These results indicated that the fibbers of sciatic nerve in the gangliosides pretreated groups were normal nerve fibbers, and gangliosides here prevented nerve degeneration, and not promoted nerve regeneration, suggesting the pretreated gangliosides were stored in the dynamic gangliosides pool in the body. When the nerves are damaged, those gangliosides can nourish the nerves, join the process of nerve repair, and prevent the nerve degeneration. The number of fibbers in the 50 mg·kg -1 gangliosides pretreated groups was obviously higher than that in 20 mg·kg -1 pretreated groups in either d 7 or d 11; The number of fibbers in d 7 were also higher than that in d 11 in both 50 mg·kg -1 and 20 mg·kg -1 pretreated groups. CONCLUSIONS: Enough amount of gangliosides stored in the body before nerve injury is important for the prevention of wallerian degeneration of nerve.