大鼠急性脊髓损伤后Bak基因的表达及其意义

摘要

Objective Investigate the expression and significance of Bak gene after acute spinal cord injuries of rats. Methods The selected 64 SD rats were randomLy divided into model and control groups (n=32).In the model group,make the animal models of rats acute spinal cord injuries by the modified Allen's method and only do laminotomy and don't injury Spinal cord in the control group.Estimate the function of nerves on the third hour,first day,third day, seventh day after the operation by the modified Allen's method. Then put the animal to death and observe the morphological changes and characteristics of the Bak gene expression by the HE staining and the immunohistochemisty staining on the damaged part of the spinal cord. Then detect the neuronal cell apoptosis by the TUNEL method.Indicate the result by the IOD and AI using the Motic.med 6.0. Results There was no obvious leg dysfunction or myoloid tissue morphological abnormalities for rats in Control group with significantly higher Tarlov grade than that of Model group (P < 0.05), while rats in Model group presented a obvious leg dysfunction which myoloid tissue was in conditon of hemorrhage,edema,apoptosis and necrosis. There was no obvious Bak gene expression in rats' myoloid tissue of Control group,which was significantly lower than that of Model groupat each time point (P<0.05). The Bak gene expression of Model group was first found 3h after modeling, which up-regulated continuous utill 3d after modeling (P<0.05), and down-regulated obviously after 7 d after modeling (P<0.05). Conclusion The spinal cord injury can activate Bak gene, thus lead to neuronal cell apoptosis. This may be one of the important mechanism of the disease progress.%目的探讨Bak基因在大鼠急性脊髓损伤（ASCI）中的表达及其意义。方法选取64只SD大鼠随机分为模型及对照两组，每组32只，模型组以改良Allen's法制作SD大鼠急性脊髓损伤动物模型，对照组只行椎板切开不损伤脊髓。分别于伤后3 h、1、3、7 d时（每个时间点8只）应用改良Tarlov评分法评价其神经功能；然后处死动物，取受损节段脊髓行HE染色及免疫组化染色，观察形态学改变和Bak基因表达的特点；并应用TUNEL方法检测神经细胞凋亡情况。其量的评定借助于麦克奥迪数码医学图像分析系统A（Motic.med 6.0）软件，结果分别用累积光密度及细胞凋亡指数来表示。结果对照组大鼠下肢功能均无明显瘫痪，模型组大鼠下肢均出现不同程度功能障碍，对照组各时间点的Tarlov评分均高于实验组（P＜0.05）。对照组各时间点脊髓组织未见明显出血、水肿和细胞凋亡坏死，模型组各时间点脊髓组织均有不同程度出血、水肿、细胞凋亡及坏死。对照组未见明显Bak基因表达，模型组各时间点Bak基因表达均明显高于对照组（P＜0.05），模型组内Bak基因表达3 h点出现，1 d增加，3 d达高峰，7d明显减少。模型组内细胞凋亡3h点少量出现，1d增加，3d达高峰，7d明显减少。结论脊髓损伤激活Bak基因表达，从而诱导神经细胞凋亡，可能为其病情进展的重要机制之一。