脊髓损伤大鼠触液神经元中p75NTR的表达

Expression of p75NTR in cerebrospinal fluid-contacting neurons of rats with spinal cord injury

中文关键词:  脊髓损伤  触液神经元  p75神经营养因子受体

英文关键词:Spinal cord injury  Cerebrospinal fluid-contacting neurons  P75 neurotrophin receptor

中文摘要:

  【摘要】 目的：探讨大鼠触液神经元（cerebrospinal fluid-contacting neurons，CSF-CNs）p75神经营养因子受体（p75 neurotrophin receptor，p75NTR）在脊髓损伤后的表达变化。方法：成年雌性Sprague-Dawley（SD）大鼠36只，按随机数字表法分为正常对照组（6只）、假手术组（6只）和脊髓损伤组（24只），脊髓损伤组采用Allen′s打击模型（10g×3cm）在大鼠脊髓T10段造成急性脊髓损伤，分别于损伤3d、1周、2周、4周后进行取材；对照组不做任何处理，假手术组只暴露脊髓，不击伤脊髓。对各组大鼠运动功能行BBB评分，各时间点取材行病理切片HE染色观察。取材前48h侧脑室注射霍乱毒素B亚单位与辣根过氧化物酶复合物（CB-HRP）特异性标记触液神经元。处死大鼠后，取损伤的脊髓节段10mm，用免疫荧光双标法检测触液神经元p75NTR的表达，Image-Pro Plus计数目标神经元CB-HRP/p75双阳性细胞的数目。结果：假手术组各时间点BBB评分均为21.0±0；脊髓损伤组在术后3d、1周、2周、4周各时间点BBB评分分别为3.20±0.81、10.73±1.02、12.48±1.86、13.29±1.93，两组各时间点差异均具有统计学意义（P<0.05）。HE染色可见正常对照组和假手术组脊髓组织结构完整，细胞形态正常；脊髓损伤组脊髓组织结构紊乱，神经元变性坏死，胶质细胞增生，胶质瘢痕和脊髓空洞形成。免疫荧光双标示正常对照组和假手术组可见少量CB-HRP/p75双阳性细胞，计数分别为5.16±0.55、4.31±0.61，两组比较差异无统计学意义（P>0.05）；脊髓损伤组伤后3d、1周、2周CB-HRP/p75双阳性细胞数分别为13.35±1.53、21.68±2.15、16.26±2.09，与正常对照组和假手术组比较差异均有统计学意义（P<0.05），伤后4周时，CB-HRP/p75双阳性细胞数为4.83±0.73，与正常对照组和假手术组比较差异无统计学意义（P>0.05）。结论：p75NTR可在大鼠脊髓触液神经元中表达，且在脊髓损伤后表达增加，触液神经元可能通过p75NTR参与脊髓损伤的修复过程。

英文摘要:

  【Abstract】 Objectives: To investigate the changes in expression of p75 neurotrophin receptor(p75NTR) in cerebrospinal fluid-contacting neurons(CSF-CNs) of rats with spinal cord injury. Methods: Thirty-six female adult Sprague-Dawley(SD) rats were randomly divided into normal control group(n=6), sham operation group(n=6) and spinal cord injury group(n=24). Allen′s weight-drop method(10g×3cm) was adopted to induce acute spinal cord injury at T10 segment． Rats were sacrificed at 3 days and 1, 2 and 4 weeks respectively after injury． All animals were evaluated on the hind limb behavior with BBB locomotor score. HE staining was performed at different time points. Intracerebroventricular injection of cholera toxin subunit B with horse radish peroxidase(CB-HRP) was performed to specifically mark CSF-CNs at 48h before animals were sacrificed at each time point． After rats were sacrificed, double immunofluorescence staining was performed at spinal site within 10mm away from the injury to detect the expression of p75NTR in CSF-CNs. Software Image-Pro Plus was used to count the positive neurons. Results: The BBB score of sham operation group at each time point was 21.0±0. The BBB score of spinal cord injury group at each time point of 3 days and 1, 2 and 4 weeks after injury was 3.20±0.81, 10.73±1.02, 12.48±1.86, 13.29±1.93 respectively. There were significant differences between the two groups at different time points(P<0.05). HE staining showed that in normal control group and sham operation group, the structure of spinal cord was complete and the cell morphology was normal; in spinal cord injury group, disorder of spinal cord tissue, degeneration and necrosis of nerve cells, proliferation of glial cells, formation of glial scar and spinal cord porosis were found. Double immunofluorescence staining showed that there were a few CB-HRP/p75 double positive cells in normal control group and sham operation group. The number of CB-HRP/p75 double positive cells in these two groups was respectively 5.16±0.55, 4.31±0.61. There was no significant difference between the two groups(P>0.05). The number of CB-HRP/p75 double positive cells in spinal cord injury group at 3 days and 1, 2 and 4 weeks after injury was 13.35±1.53, 21.68±2.15, 16.26±2.09 respectively. Compared with normal control group and sham operation group, the difference was statistically significant(P<0.05). At 4 weeks after injury, the number of CB-HRP/p75 double positive cells was 4.83±0.73. Compared with normal control group and sham operation group, the difference was not statistically significant(P>0.05). Conclusions: p75NTR is expressed in CSF-CNs of the normal rats and its expression increases after acute spinal cord injury． CSF-CNs might participate in the repair of spinal cord injury via p75NTR．