完全横断性脊髓损伤后跨神经元变性的实验研究

目的：探讨大鼠完全性脊髓损伤后损伤平面以下下运动神经元轴突参与组成的周围神经的变化及其变化规律，为临床治疗、康复及预后的判断提供相关的理论基础。方法：48只成年雄性Wistar大鼠随机分为假手术组和脊髓损伤组，各组24只，每组均对应分为7d、1个月、2个月、3个月4个时间点，每组每个时间点6只大鼠。完全性脊髓损伤组大鼠制作T10水平完全性脊髓横断模型。在预定取材时间点处死相应动物，自腓总神经入肌点处向近端切取10mm该神经，分别行天青美-蓝染色光镜观察及超微结构观察。结果：各时间点假手术组腓总神经光镜下观察，神经纤维排列均匀；轴突外形正常、染色均匀。超微结构观察，髓鞘外形正常，板层清晰；轴索位置正常，轴索内微丝微管正常。完全性脊髓损伤组光镜观察发现腓总神经髓鞘和轴索出现明显退变，且退变随时间推移逐渐加重，同时出现轴突发芽现象。超微结构观察可见轴索内线粒体肿胀．轴浆内微丝、微管溶解，髓鞘板层结构破坏，雪旺氏细胞增生及空泡变性现象。退变的同时．腓总神经出现大量的新生神经纤维即轴突发芽现象。结论：完全性横断性脊髓损伤后周围神经存在退变现象．且退变程度随时间的延长逐渐加重，说明大鼠完全横断性脊髓损伤可以导致损伤水平以下周围神经发生跨神经元变性。

Transneuronal degeneration distal to the lesion after complete spinal cord injury in rats

Objective:To investigate the characteristic changes of the periphery nerves composed of motorneurone axons distal to the complete spinal cord injury and provide foundation for the clinical treatment,rehabilitation and evaluation of prognosis.Method:48 male Wistar rats were divived into sham and spinal cord injury group.24 rats were subjected to T10 spinal cord complete transection after laminectomy,24 rats were sham-operated.The sham-operated animals underwent an identical surgical procedure excluding the resectioning of the cord.Rats were sacrificed at 7days,1 month,2 month and 3 month and the common peroneal nerve were harvested right before its entrance into the muscle,with 6 rats for each time point from each group.The nerve were observed under light microscope and electronic microscope for morphological changes.Result:Nerves collected from the sham-operated control group at different time points showed normal nerve arrangement,normal axon shape under light microscope while under electronic microscope it showed normal nerve sheath,clear lamination,normal axon position and normal microfilaments and microtubules inside the axon.Nerves from spinal cord injury group,however,showed apparent degeneration of the sheaths and axons of the common peroneal nerve under light microscope,and the degeneration worsened over time.Sprouting of axons were also observed.Under electronic microscope,they showed swelling of mitochondria inside the axon and desolving of microfilament and microtubule,destruction of lamina structure of the nerve sheath,hyperplysia and vesicular degeneration of schwann cell.A large number of axonal sprouting appeared at the same time of degeneration.Conclusion:Peripheral nerve degeneration appeares following complete transection of thoracic spinal cord and the degeneration aggravates over time which illustrates that complete transection of the spinal cord causes transneuronal degeneration of the motorneusones distal to the lesion.