大鼠脊髓损伤后骨形态发生蛋白2表达变化的规律及意义

Dynamic expression of bone morphogenetic protein 2 and its clinical significance after spinal cord injury in rat

中文关键词:  脊髓损伤  骨形态发生蛋白2  大鼠

英文关键词:Spinal cord injury  Bone morphogenetic protein 2  Rat

中文摘要:

  【摘要】 目的：观察大鼠脊髓损伤后损伤脊髓组织中骨形态发生蛋白2（BMP2）表达变化的时间及空间分布规律，探讨抑制BMP2增加的最佳时间及部位。方法：成年SD大鼠40只，随机分为5组：假手术组，损伤后1d组、3d组、7d组、14d组，每组8只。将大鼠麻醉后以T10棘突为中心，打开椎板，暴露脊髓，各损伤组使用NYU impactor打击器制作大鼠脊髓损伤模型，假手术组不做打击处理。分别于造模前后对各组大鼠进行运动功能BBB评分，于预定时间点处死动物，取损伤段（假手术组取相应节段）脊髓组织行HE染色和免疫组化染色，观察脊髓组织学改变并进行阳性细胞计数，采用方差分析进行组间比较。结果：造模前各组大鼠的BBB评分均为21分；造模后假手术组大鼠BBB评分高于各损伤组，且差异有显著性（P＜0.01），各损伤组之间两两比较评分均无显著性差异（P＞0.05）。HE染色假手术组大鼠脊髓组织结构清晰，层次规整，条理性强，灰质中可见较多的神经元，白质中可见大量纤维性星形胶质细胞；损伤组大鼠损伤处脊髓组织结构紊乱，层次感消失，可见弥散的血细胞，早期增多较晚期明显，脊髓灰质与白质中都可见因大量组织细胞溶解而遗留的组织空洞。各组脊髓灰、白质中均有BMP2表达，假手术组灰质中平均阳性细胞数为1.53±0.38个/HP，白质中为0.77±0.14个/HP；损伤后1d组灰质中为13.70±4.81个/HP，白质中为7.23±3.14个/HP；损伤后3d组灰质中为9.37±3.61个/HP，白质中为5.63±2.23个/HP；损伤后7d组灰质中为6.17±1.81个/HP，白质中为4.17±1.24个/HP；损伤后14d组灰质中为4.36±1.60个/HP，白质中为1.87±1.13个/HP；损伤各组BMP2平均阳性细胞数与假手术组相比较均有明显差异（P＜0.01），各组灰质区BMP2平均阳性细胞数的增加均较白质区更为显著（P＜0.01）。结论：脊髓损伤后损伤脊髓组织中BMP2的表达增加，损伤后1d最高，主要集中在损伤区灰质区。针对BMP2进行特异性抑制最好在损伤后第一天的脊髓灰质区实施。

英文摘要:

  【Abstract】 Objective：To observe the dynamic expression of bone morphogenetic protein 2（BMP2） after spinal cord injury in rat，especially the changes on different time point and in different site，and to investigate the optimal time point and site for inhibiting BMP2 expression.Method：A total of 40 Sprague Dawley rats were randomly assigned into 5 groups：1-day-after-impact group，3-day-after-impact group，7-day-after-impact group，14-day-after-impact group and sham operation group with 8 rats in each group.After making skin incision centered as T10，the whole T10 and T9 and T11 partial laminar were removed to expose the spinal cord.Spinal cord injury models were created by NYU impactor.After that，behavior testing of all rats was assessed by using the Basso-Beattie-Bresnahan（BBB） locomotor rating scale before and after the perfusion.Each group of rats were perfused with 4% paraformaldehyde in heart on the 1st，3th，7th，14th day-after-impact，and then HE staining was used to observe the difference between the sham operation group and test groups.Meanwhile，immunohistochemistry was used to evaluate the level of BMP2 in the injuried region.Result：BBB score showed no significant difference among the spinal cord injury groups at the same time point（P＞0.05）.By HE staining， the tissue structure of sham operation group showed clear and orderly，on the contrary，it was disorderly in rest groups.According to the result of immunohistochemistry，significant difference was detected between the model group and sham operation group（P<0.05）.Compared with the sham operation group，the mean number of BMP2 positive cells in 1-day-after-impact group was 13.70±4.81 and 7.23±3.14 for the gray and white matter respectively，9.37±3.61 and 5.63±2.23 in 3-day-after-impact group，6.17±1.81 and 4.17±1.24 in 7-day-after-impact group，and 4.36±1.60 and 1.87±1.13 in 14-day-after-impact group.The BMP2-positive cells in gray matter increased more significantly than white matter（P<0.01）.Conclusion：The number of BMP2-positive cells increase after SCI，and reach peak at 14d，the specific inhibition of BMP2 should be performed in gray matter at 1d after SCI.