大鼠头颅瞬间旋转致脑弥漫轴索损伤的形态学观察与机理探讨

The observation of morphological changes and the exploration of mechanism in diffuse axonal injuries in rats by instant head rotation

目的：观察大鼠头颅瞬间旋转引起脑神经轴索损伤的形态学改变并探讨其机理。方法：ＳＤ大鼠２１只（对照组３只，损伤组１８只）。采用自制头颅旋转致伤装置，将损伤组大鼠头颅于３ｍｓ内在冠状面绕脑中心右向旋转９０°造成剪力伤，于伤后６、１２、２４、７２、１４４小时分批处死动物制脑切片，行镀银及ＨＥ染色，光镜下观察神经轴索变化。结果：伤后即刻大鼠均意识丧失。３只１５分钟内死亡，肉眼亦见蛛网膜下腔广泛出血。其余存活大鼠在伤后６至１４４小时，肉眼见蛛网膜下腔广泛出血，光镜下见脑干、胼胝体、大脑脚等部的神经轴索有程度不同的肿胀、断裂、轴缩球形成等征象，以脑干纵行纤维受损最重并伴纤维束间点状出血。延髓和中脑的上述变化分别在伤后６及２４小时最重。结论：本研究成功地建立了大鼠头颅瞬间旋转脑弥漫轴索损伤模型，表明剪力可引起轴索损伤，脑微血管变化是加重轴索损伤的重要因素。

Objective: To observe and explore the morphological changes and mechanisms of neuronal axons injury in the rat brain by rotating its head injury. Methods:21 SD rats (three for sham group, eighteen for injury group) and a selfmade rotating injury device were used. In order to induce shearing injury, the heads of rats in injury group were rotated immediately within less than three milliseconds in the coronal plane by 90° to the right. The injured rats were killed at 6,12,24,72 and 144 hours post injury (three rats each time) respectively. Tissue slides of the brain were made, processed with silver and HE staining and observed under microscope. Results:All injured rats lost consciousness after injury, among which three died of diffuse subarachnoid hemmorage. The survived rats were seen grossly with diffuse subarachnoid hemmorage, and seen under microscope with the signs of various severity of axonal swelling, discontinuity and axonal retraction balls at the brainstem, corpus collosum and cerebral peduncle during 6 to 144 hours post injury. The longitudinal neuronal axons in the brainstem were found most severely injured and associated with small parenchymal bleeding spots. The above impairments were most apparent in the medulla oblongata at 6 hours post injury, and in the midbrain most apparent at 24 hours post injury. Conclusions: The present study successfully produced a rat model of brain DAI by instantly rotating injury. It verified that the shearing force can lead to DAI, and the cerebral microvascular changes are the important factor to worsen the process of DAI.