大鼠坐骨神经分支选择性损伤后脊髓背角毛细血管和星形胶质细胞的反应

目的探讨成年大鼠坐骨神经分支选择性结扎切断(SNI)后,腰段脊髓背角内毛细血管和星形胶质细胞的反应。方法成年雄性SD大鼠40只,随机分为光镜组(n=30)和电镜组(n=10)。光镜组又分为对照组、假手术组和SNI手术组。SNI手术为分别结扎切断左侧胫神经和腓总神经,保留腓肠神经,存活20d。部分动物在术后经尾静脉给予30g/L伊文思蓝,切取脊髓L4平面,荧光显微镜观察伊文思蓝的渗出;另一部分在术后进行常规固定取材,切片进行抗鼠IgG和GFAP的免疫组织化学反应。电镜组(对照组和SNI后20d组),脊髓切片进行常规抗大鼠IgG的免疫电镜处理。结果 1.SNI后20d,可见明显的伊文思蓝渗出红色光斑;2.SNI后GFAP阳性细胞变为反应型,数量明显增加,毛细血管壁及其周围的IgG颗粒也显著增加。3.电镜观察:SNI术后20d,IgG阳性颗粒增多,内皮细胞观察到下列变化:(1)内皮细胞向管腔内伸出许多微细的突起,有的含有IgG阳性颗粒。(2)内皮细胞的管腔侧胞膜上有许多"内吞"小凹,凹内可见IgG阳性颗粒,胞质内有含IgG阳性颗粒的小泡,在反管腔侧胞膜上有"胞吐"现象。(3)内皮细胞紧密连接出现间隙,间隙内有IgG颗粒。(4)胞质内出现囊泡,有的泡内显示IgG阳性颗粒。结论 SNI后脊髓背角内毛细血管内皮细胞发生明显的反应,大鼠IgG和伊文思蓝可经过血脊髓屏障渗出,星形胶质细胞被激活。

Response of the capillaries and astrocytes in the spinal cord dorsal horn of rats induced by spared nerve injury

Objective To investigate the response of the capillaries and astrocytes in the spinal cord dorsal horn of rats after the spared nerve injury (SNI). Methods Male SD rats were randomly divided into two groups and used for light microscopy(n=30) or electromicroscopy(n=10) study respectively. The rats for light microscopy study were divided into control, sham-SNI and SNI subgroups. Ten rats were performed SNI operation and survived for 20d respectively. Five of them were injected Evans blue into caudal vein, 30min before perfusion, the L4 segment of spinal cord was removed and cut into 30 μm frontal sections on a cryostat. The section was detected under Olympus BX 51 fluorescent microscope. Other five of them were perfused, the sections were performed anti-rat IgG and glial fibrillary acidic protein (GFAP, a marker for astrocyte) immunohistochemical staining (ABC method). Rats used for immunoelectromicroscopy were divided into control and SNI 20 days subgroups, the spinal cord sections were performed anti-rat IgG immuno-electromocroscopic staining. Results 1. On 20 days after SNI, many clear red effusion spots of Evans blue were observed in the dorsal horn. 2. SNI induced astrocytes became active type and the number were increased; IgG positive granules on the capillary wall and perivascular space were increased markedly.3. Immunoelectromicroscopy showed that at 20 days after SNI, IgG positive granules were increased, the following changes of the endothelial cells were found: (1)Many micro processes extended from the endothelial cells were observed, some of them contained IgG positive granules. (2)Many “endocytosis concave” on the luminal side, vesicles in cytoplasm and “exocytosis steps” on aluminal side of endothelial cells containing IgG positive granules were observed respectively. （3）The tight junction of endothelial cells revealed gap and containing IgG positive granules.(4) Many “vesicles” revealed within the cytoplasm, some of them contained IgG positive granules and some did not. Conclusion After SNI the