脊神经后根切断大鼠脊髓后角神经元和星形胶质细胞变化及白细胞介素1β和胶质纤维酸性蛋白的表达

Changes in sensory neurons and astrocytes and the expression of interleukin lbeta and glial fibrillary acidic protein in the rat spinal cord after selective dorsal rhizotomy

背景:脊髓损伤后星形胶质细胞过度角质化对脊髓的修复再生既有积极作用又有消极作用,如何调控星形胶质细胞角质化到一个合适的程度,以使其充分发挥正作用是脊髓损伤的一个研究重点。目的:观察脊神经后根切断对大鼠脊髓后角神经元、星形胶质细胞及白细胞介素1β和胶质纤维酸性蛋白表达的影响。方法:取33只成年Wistar大鼠,采用随机抽签法分为对照组(n=3)与实验组(n=30)。分离暴露实验组大鼠左右侧第3,4腰椎神经后根,切断左侧第3,4腰神经后根(实验组手术侧),右侧不做处理(实验组对照侧);对照组大鼠不做任何处理。术后1,2,4周麻醉后处死大鼠,取第3,4腰脊髓组织,苏木精-伊红染色观察脊髓后角神经元和星形胶质细胞形态学变化,免疫组化染色观察脊髓后角白细胞介素1β和胶质纤维酸性蛋白的表达。结果与结论:①苏木精-伊红染色:脊神经后根切断后1,2周,实验组手术侧感觉神经元的细胞核和胞浆均发生变化,术后4周神经元出现细胞凋亡;星形胶质细胞活化,细胞增多、胞体增大、突起增多,其数量于术后2周达峰值;实验组手术侧术后2,4周的感觉神经纤维数量少于实验组对照侧、对照组(P<0.05),术后1,2,4周的星形胶质细胞数量多于实验组对照侧、对照组(P<0.05);②免疫组化染色:脊神经后根切断后,实验组手术侧白细胞介素1β和胶质纤维酸性蛋白阳性表达增强,于术后2周达峰值,实验组手术侧术后1,2,4周的胶质纤维酸性蛋白与白细胞介素1β阳性细胞平均吸光度值均高于实验组对照侧、对照组(P<0.05);③结果表明,脊神经后根切断可引起脊髓后角感觉神经元数量减少、星形胶质细胞反应性增殖,增强白细胞介素1β和胶质纤维酸性蛋白表达。

BACKGROUND:Excessive keratinization of astrocytes after spinal cord injury forms a mechanical barrier to repair the spinal cord and also plays an active role in spinal cord repair and regeneration.The regulation of keratinization to a suitable extent,to make it fully exert positive effects and decrease negative effects,is really a challenge to the research of spinal cord injury.OBJECTIVE:To observe the alteration of sensory neurons and astrocytes in the rat spinal dorsal horn,as well as the expression of interleukin-1βand glial fibrillary acidic protein in the abovementioned cells after a selective dorsal rhizotomy.METHODS:Thirty-three adult healthy Wistar rats were randomly divided into control group(n=3)and experimental group(n=30).On the operation side of the experimental group,the dorsal roots of the left lumbar 3 and 4 spinal nerves were exposed,separated,and cut off,while on the control side of the experimental group,the dorsal roots of the right lumbar 3 and 4 spinal nerves were only exposed and separated.The control group did not undergo any treatment.The rats were sacrificed under anesthesia at 1,2,and 4 weeks after operation,and the segmental tissues of lumbar segments 3 and 4 were taken to make paraffin sections.The morphological changes of neurons and astrocytes in the rat spinal dorsal horn were observed by hematoxylin-eosin staining.The expression of interleukin-1βand glial fibrillary acidic protein in the spinal cord dorsal horn was observed by immunohistochemical staining.RESULTS AND CONCLUSION:(1)Hematoxylin-eosin staining:1 and 2 weeks after selective dorsal rhizotomy,there were changes in the nuclei and cytoplasm of sensory neurons on the surgical side of the experimental group and at 4 weeks after operation,apoptosis in neurons appeared.Astrocytes were activated and the number of the cells increased accompanied by enlarged cell body and increased processes and reached a peak at 2 weeks after operation.The number of sensory nerve fibers on the surgical side of the experimental group was less than that on the control side of the experimental group and in the control group at 2 and 4 weeks after operation(P<0.05),while the number of astrocytes was higher than that on the control side of the experimental group and in the control group at 1,2,and 4 weeks after operation(P<0.05).(2)Immunohistochemical staining:The positive expressions of interleukin-1βand glial fibrillary acidic protein on the surgical side of the experimental group were enhanced and peaked at 2 weeks after selective dorsal rhizotomy.The average absorbance values of glial fibrillary acidic protein and interleukin-1βpositive cells on the surgical side of the experimental group were higher than those on the control side of the experimental group and in the control group(P<0.05).(3)To conclude,selective dorsal rhizotomy can lead to a decrease in the number of sensory neurons in the dorsal horn of the spinal cord,reactive proliferation of astrocytes,and increased expression of interleukin-1βand glial fibrillary acidic protein.