大鼠脊髓进行性压迫性损伤半胱氨酸蛋白水解酶-12表达与细胞凋亡

Apoptosis and caspase-12 expression in progressive compressive spinal cord injury:experiment with rats

目的探讨大鼠脊髓进行性压迫损伤细胞凋亡、半胱氨酸蛋白水解酶(caspase-12)表达变化规律及其关系。方法随机选用健康成年 Wistar 大鼠120只,分为两组:手术组和对照组各60只,每个时间点各10只,按自行设计的方法作脊髓压迫模型;对照组,仅做脊髓显露。分别于术后1、3、7、14、21、28 d 观察脊髓受压后细胞凋亡及 caspase-12的表达变化系。结果在各压迫组神经细胞出现凋亡,凋亡的发生率在1、3、7、14、21、28 d 分别为12.5%±2.3%、13.0%±3.6%、17.2%±4.3%、29.4%±4.4%、36.1%±6.5%、2.3%±7.9%,并伴随 caspase-12的表达增强而增加,14、21、28 d 组间比较差异有统计学意义(均 P<0.05)。结论 caspase-12可能参与了脊髓进行性压迫缺血所致的细胞凋亡。

Objective To investigate thee apoptosis and caspase-12 expression in progressive compression of spinal cord （PCSC）. Methods 120 adult Wistar rats were randomly divided into 2 equal groups, experimental group, undergoing operation so as to establish PCSC models, and control group, undergoing sham operation. 1, 3, 7, 14, 21, and 28 days after the operation, 5 rats from each group were anesthetized with their spinal cords taken out. TUNNEL method was used to observe the apoptosis of the neurons in the compressed segments. Another 5 rats from each group at different time points were anesthetized with their spinal cords as well. Immunohistochemistry was used to detect the mRNA expression of caspace-12 in the compressed segments. Western blotting was used to detect the protein expression of caspace-12. Results The apoptotic rates of neurons and gliocytes 1, 3, 7, 14, 21, and 28 days after were 12.5% ±2.3%, 13.0% ±3.6%, 17.2% ±4.3%, 29.4% ±4.4%, 36.1% ±6.5%, and 2.3% ± 7.9% respectively, with significant differences among the values 14, 21, and 28 days and those at other time points after the operation （ all P 〈 0. 05 ）. Immunohistochemistry showed that the number of caspace-12 positive neurons increased since 1 day after, and became remarkably high 14, 21, and 28 days after with significant differences among different time points （ all P 〈 0. 05 ）. Western blotting showed that the protein expression of caspace-12 was low 1, 3, and 7 days after, and peaked 14 days after, and then gradually decreased, however, the expression levels 21 and 28 days after were still significantly higher then those 1, 3, and 7 days after （ all P 〈 0. 05 ）. Conclusion Caspase-12 is involved in the apoptosis of neurons in PCSC.