大鼠臂丛放射性损伤后脊髓前角运动神经元病理变化及c-fos基因表达

目的模拟乳癌放疗方案，观察实验大鼠臂丛神经受照射后相应脊髓前角运动神经元的病理改变及c—fos基因表达。方法采用剂量分割照射方案，建立大鼠臂丛神经放射性损伤动物模型。将加只SD大鼠随机分成臂丛神经损伤组（实验组）和正常对照组，实验组又根据损伤后取材时间的不同分成损伤后3、5、7和9周4个时间组，每个时间组和对照组各4只大鼠，每个时间组以左侧为照射侧，右侧为对照侧，采用日照射2Gy／次，每周5次深部X线照射，累计剂量达到30Gy后，分别于末次照射后3、5、7和9周取材。检测两侧脊髓前角运动神经元形态及数目变化并以免疫组织化学染色法检测c—fos在前角运动神经元中的表达。结果大鼠臂丛神经受照射后3周，实验组照射侧脊髓前角运动神经元存活数目随时间延长而明显减少，神经元内有明显的c—fos染色，c—fos阳性细胞数渐减。照射后9周，c-fos阳性细胞偶见。结论大鼠臂丛神经受大剂量X线照射后可使大鼠脊髓前角运动神经元存活数目明显减少；与脊髓神经元凋亡相关的c—fos基因呈阳性表达，表明原癌基因的表达在臂丛神经放射损伤的凋亡、损伤和修复过程中起重要作用。

The pathological changes of motor neurons and the expression of c-fos in ventral horn of spinal cord after radiation induced brachial plexus injury of rats

Objective Simulated the therapy protocol for breast cancer,to observe the pathological changes of motor neurons in ventral horn in spinal cord and the expression of c-los gene.Methods The RIBPI animal models were established by divided-dose of radiation.The rats were divided randomly into bra- chial plexus injury groups (experiment groups) and control group.Using 2 Gy/time,5 times/week with a total administered dose of 30 Gy reached in 3 weeks,experiment groups were divided into different-time groups after radiation as 3-week,5-week,7-week and 9-week group.There were 4 rats in each time group and control group.In each time group,the left was the radiation side,the right was the control side.We draw the material in the different time after the last time radiation.The morphological changes and counts of the motor neurons in ventral horn and axons of bilateral spinal cord have been detected.Meantime,the expression of c-fos gene has been detected in motor neurons in ventral horn by ICN methods.Results 3 weeks after radiation,the ac- count of motor neurons in ventral horn was significantly decreased in the radiation side with time extending. The expression of c-los in motor neurons was significantly detected.Afterward,the positive cells reduced grad- ually.9 weeks after radiation,the positive cells seldom appeared.Conclusion The result indicated that large dose of X radiation on braehial plexus on rats,can induced the account of motor neurons in ventral horn significantly decrease in the radiation side.The apoptosis associated c-fos significantly expressed in motor neu- rons in spinal cord,and it indicated that oneogene c-fos maybe take an important effect in apoptosis,injury and recover of radiation induced brachial plexus injury.