三重脑震荡鼠模型建立及组织病理学动态改变观察

Establishment a rat model of multiple cerebral concussion and histopathological changes after injury

目的建立三重脑震荡（MCC）大鼠模型，观察MCC鼠不同结构神经元及轴索的病理学变化，探索运动员多次脑震荡损伤机制。方法用金属单摆闭合性脑损伤打击装置复制大鼠MCC模型48只，随机分为1、2、4、8、16和24d组（n=8）。另设正常对照组（n=8）。定时戊巴比妥钠麻醉，4％多聚甲醛心腔灌注处死，取脑。用Nissl染色、Bielschowsky银染和Weil髓鞘染色显示神经元、轴索和髓鞘，对固缩变性神经元数目、轴索直径和髓鞘变性进行半定量分析。结果伤后：①1～24d皮层、海马和脑干网状结构神经元不同程度固缩变性，以2d组为重；②轴索不同程度的肿胀、变形、排列紊乱、收缩球形成；轴索直径平均值均大于对照组，以2、4d组最为明显（P〈0．05）；③髓鞘肿胀、淡染，灰度值增高，与对照组相比，1～16d组均有统计学意义（P〈0．05）。结论大鼠MCC后，脑神经元出现不同程度弥漫性的固缩变性，轴索肿胀、髓鞘淡染的病理改变。

Objective To develop a new model of multiple cerebral concussion （MCC） in rats and observe the histopathologieal changes of neural axons and myelin sheath in different areas of the brain postinjury. Methods A multiple cerebral concussion model was established using a metallic pendulum-striker concussive device with one impact each day for 3 days. Forty-eight male Sprague-Dawley rats were randomly divided into 6 MCC groups： 1 d group, 2 d group, 4 d group, 8 d group, 16 d group and24 d group post-injury （n =8）. One control group was used （n = 8 ）. The brain was obtained after the rats were anesthetized with pentobarbital and killed with 4% paraformaldehyde peffnsed on schedule. Neurons, axons and myelin sheath were showed by Nissl staining, Bielsehowsky＇s silver stain and Weil＇s myelin stain. The pycnotic neurons, the diameter of axons and the grey value of myelin sheath were measured by semiquantitative analysis, respectively. Results （1）The pycnotic neurons were observed in cerebral cortex, dorsal hippocampns, dentate gyrus and brainstem reticular formation after MCC in each group. The number of damaged neurons at 2 d group reached a peak. （2）The pathological changes of axons were observed, including axonal swelling, deformation, disorganization of axon and formation of retraction bulbs. The axon diameter in each group was larger than that in control group, with the largest diameter in 2 d group and 4 d group （P 〈0.05）. （3）Myelin sheath showed swelling and poor-staining after injury. The grey values in 1 d, 2 d, 4 d, 8 d, 16 d group were significantly different compared with the control group （P 〈 0. 05）. Conclusion After MCC, the pathological changes, such as pycnotic neurons, axon swelling, and poor-staining of myelin sheath are observed.