大鼠脊髓损伤减压后神经功能恢复与Fas表达的相关性研究

RELATIONSHIP BETWEEN Fas EXPRESSION AND RECOVERY OF NEUROLOGICAL FUNCTION AFTER SURGICAL DECOMPRESSION IN SPINAL CORD INJURY RAT MODEL

目的通过环扎法制备大鼠急性脊髓损伤(spinal cord injury,SCI)模型,研究不同时间点减压后细胞凋亡基因Fas的表达规律及与神经功能恢复的关系。方法 13周龄雄性SD大鼠100只,体重255～376 g,随机分为4组,每组25只。A组为对照组,仅行椎板切除;B、C、D组均采用环扎法建立急性SCI模型,B、C组分别于术后8、72 h行脊髓减压,D组术后不行脊髓减压。于术后1、3、7、14、21 d采用BBB评分及斜板实验评分评价神经功能恢复情况;处死动物取材行HE染色、免疫组织化学染色观察Fas表达,TUNEL标记观察细胞凋亡水平。结果 A组术后各时间点BBB评分和斜板实验评分均明显优于B、C、D组,3、7、14、21 d时B组优于C、D组,C组优于D组,差异均有统计学意义(P<0.05)。A组各时间点脊髓组织结构及形态清楚,未见出血、水肿和变性坏死的神经元。术后1 d,B、C、D组脊髓组织明显出血、水肿,可见神经元死亡,D组较显著;3、7 d,B组细胞变性较C、D组轻;14、21 d,B组损伤区可见较少胶质细胞,有纤维母细胞增生和修复现象,C、D组脊髓内有部分坏死、囊腔及空洞形成。A组术后各时间点均少见Fas和TUNEL阳性细胞;B、C、D组术后各时间点均见Fas和TUNEL阳性细胞,3 d达峰值,7 d表达减弱,21 d仍有表达;其中D组阳性细胞数最多,B组少于C、D组,差异均有统计学意义(P<0.05)。结论 SCI后早期减压有利于大鼠神经功能的恢复,Fas信号通道可能在诱导SCI后神经细胞凋亡的过程中发挥重要作用。

Objective To investigate the relationship between the expression of apoptosis-related gene Fas and recovery of neurological function after surgical decompression at different time points in acute spinal cord injury（SCI） rat model by cerclage.Methods A total of 100 13-week-old male Sprague Dawley rats（weighing,255-376 g） were randomly divided into 4 groups（n=25）.The rats only received laminectomy in group A as control;the rats were made the acute SCI models by cerclage in groups B,C,and D.The spinal cord decompression was performed in group B at 8 hours and in group C at 72 hours,no spinal cord decompression in group D.At 1,3,7,14,and 21 days,Basso-Beattie-Bresnahan（BBB） score and inclined plane test were used to evaluate the recovery of neurological function;the neuronal apoptosis level of spinal cord was examined by TUNEL staining;HE staining and immunohistochemical staining were applied to analyze the expressions of Fas.Results The BBB score and inclined plane test score in group A were significantly better than those in groups B,C,and D at different time points（P 0.05）;group B was significantly better than groups C and D,and group C than group D at 3,7,14,and 21 days（P 0.05）.In group A,no bleeding,edema,or necrosis was found.The edema,hemorrhage,and neuron death were observed in spinal cord tissue of groups B,C,and D at 1 day after operation,especially in group D.The degree of cell degeneration in group B was lighter than that in groups C and D at 3 and 7 days after operation;few glial cells and fibroblast proliferation were found at damaged zone in group B at 14 and 21 days,but necrosis and cystic cavity in groups C and D.Fas and TUNEL expression was little in group A at different time points.Fas and TUNEL were expressed in groups B,C,and D;the expressions of Fas and TUNEL reached the maximum at 3 days,and then gradually decreased at 7 and 21 days.The number of positive cells was highest in group D,and the number of positive cells in group B was significantly less than that in groups C and D（P 0.05）.Conclusion Early decompression of SCI is beneficial to recovering the neurological function.The Fas signal pathway may play an important role in the apoptosis of neuron and glial cells after SCI.