康复训练对脑缺血大鼠脑皮质突触超微结构的影响

Effects of rehabilitation training on brain cortex synaptic ultrastructure after cerebral ischemia

目的观察康复训练对脑缺血大鼠脑皮质突触密度及突触超微结构的影响。方法采用随机数字表法将60只SD大鼠分为假手术组、脑缺血组及康复训练组。根据Zea-longa等介绍的方法加以改进将脑缺血组及康复训练组大鼠制成脑缺血模型，假手术组大鼠制模方法同前，但术中不阻断大脑中动脉血流。脑缺血组及假手术组大鼠于制模后均置于普通笼内饲养，期间自由活动、进食；康复训练组大鼠于制模后给予运动训练，包括平衡木、转棒及网屏训练等。各组大鼠于制模后第1天、第7天、第14天及第21天时在透射电镜下观察其突触密度和突触超微结构变化情况。结果假手术组大鼠脑皮质神经毡内突触数量较多，突触前后成分境界清楚、轮廓完整，突触前终末内突触小泡数量较多，分布密集而均匀、大小均等。脑缺血组大鼠随着缺血时间延长，其神经毡内突触数量逐渐减少，突触结构也发生异常改变，如突触前、后膜模糊不清，突触前终末内突触小泡数量减少、破裂甚至融合；到制模后第21天时，可见突触小泡显著减少甚至消失，突触前、后膜被破坏，突触典型结构已不存在。康复训练组从制模后第7天开始，其突触损伤程度均明显轻于脑缺血组，可见该组大鼠神经毡内突触及突触小泡数量均显著多于脑缺血组。结论脑缺血大鼠可见脑皮质内突触数量明显减少，突触结构也遭到一定程度破坏；康复训练有助于脑缺血大鼠神经突触恢复正常，从而加速其神经及运动功能恢复。

Objective To study the effects of rehabilitation training on the synaptic ultrastructure of the brain cortex after cerebral ischemia. Methods Sixty rats were randomly divided into a sham operation group, a cerebral ischemia group and a rehabilitation training group. A model of focal cerebral ischemia was created in the rats of the cerebral ischemia and rehabilitation training groups. The rehabilitation training group was given balancing, grasping, rotation and walking training every day. The sham operation group and cerebral ischemia group were kept in normal cages, taking food and moving freely. Electron microscopy was used to observe the density and ultrastructure of the cortical synapses at days 1, 7, 14 and 21 after the operation. Results In the sham operation group there were numerous synaptic terminals in the cortical neuropil. The majority of synapses were Gray type II, containing spherical synaptic vesicles in presynaptic elements, After cerebral ischemia, the number of synaptic terminals had decreased and the synaptic structure was damaged. The synaptic vesicles lessened and dissolved. The presynaptic and postsynaptic membranes became unclear. At 21d after ischemia, the synaptic vesicles had disappeared and the presynaptic and postsynaptic membranes were damaged so seriously that the typical synaptic structure disappeared. After rehabilitation training, the damaged synaptic terminals recovered. Conclusions The synaptic structure was damaged after cerebral ischemia, and the damaged synaptic terminals recovered after rehabilitation training. Rehabilitation training can enhance synaptogenesis in the brain＇s cortex after cerebral ischemia and promote the recovery of motor function, at least in rats.