不同时间点减压对环扎法所致损伤脊髓Bcl-2、Bax蛋白的表达及意义

The expression and significance of Bcl-2,Bax following spinal cord injury induced by circle ligation after decompression at different time in rat.

目的:探讨不同时间点减压环扎法所致损伤脊髓中神经细胞凋亡及Bax、Bcl-2的表达及其意义。方法:成年SD大鼠84只,随机分为4组:A组,仅行椎板减压及硬脊膜囊周长测量;采用环扎法建立大鼠脊髓损伤模型,B组于环扎术后8h行脊髓减压;C组于环扎术后72h行脊髓减压;D组环扎术后不行脊髓减压。各组分别于术后1d、7d、14d、21d取材,所得脊髓标本行HE染色、Tunel染色及免疫组化法检测Bax、Bcl-2阳性细胞数等情况,并采用BBB评分评价大鼠后肢神经功能变化。结果:Bax染色:B组和C组术后1d开始阳性细胞数增加,7d时达高峰,14d时仍较明显,21d降低;D组术后阳性细胞数持续升高。Bcl-2染色:B组和C组术后阳性细胞数持续升高;D组术后1d阳性细胞数最多,之后持续降低。Tunel染色:B、C及D组术后1d开始出现凋亡细胞,7d时达高峰,以后逐渐减少,21d时仍可见。Bcl-2/Bax值与Tunel阳性细胞数关系:B组和C组二者存在负相关;D组二者呈正相关。BBB评分:A组术后1周后肢运动功能恢复正常;B组和C组术后逐渐升高(P<0.05);D组术后1天开始逐渐降低,7天时最低,然后逐渐升高。结论:环扎法可以建立稳定的大鼠脊髓损伤模型;早期减压能减少继发性脊髓损伤细胞凋亡,有利于神经功能恢复。

Objective：To evaluate the neuron apoptosis and expression of Bel-2 and Bax protein following spinal cord injury induced by circle ligation after decompression at different timepoint.Method：Eighty-four adult SD rats were divided randomly into four groups as following：group A,undergoing laminectomy and dural sac circumference measurements;group B undergoing decompression 8h later following ligation;group C undergoing decompression 72h later following ligation;group D undergoing ligation alone.Specimen of each group was harvested at 1 day,7 days,14 days and 21 days after surgery respectively.All specimens were subjected to HE staining,Tunel staining and immunohistoehemistry to evaluate the expression of Bax,Bel-2 protein.The limb function was evaluated by using the BBB seore.Result：Bax expression began to increase 1 day after decompression in group B and C,and reached peak at 7 days,while still remain visible 14 days after decompression,and then decreased at 21 days;group D increased gradually after surgery.Bel-2 expression in group B and C increased continuously after decompression,while decreased continuously in group D.Under Tunel staining,apoptosis cells in group B,C and D were evidenced 1 day after surgery,and reached peak 7 days later,then decreased,and still remained visible 21 days after surgery.Bel-2/Bax ratio and number of Tunel positive cells showed negative association in group B and C,while positive in group D.BBB score ingroup A returned to normal 1 week after operation;while it increased continuously in group B and C;BBB score in group D decreased from 1 day after operation,and reached the lowest at 7 day,then inereased gradully （P〉0.05）.Conclusion：Circle ligation seems to establish the SCI model in rat,early decompression can decrease the secondary apoptosis and promote neurofunction recovery.