坐骨神经挤压模型大鼠脊髓背角c-fos表达的研究

目的 建立大鼠坐骨神经挤压模型,观察其神经恢复过程中行为学、机械痛阈值、热缩足反射潜伏期(TWL)以及脊髓背角c-fos表达(对c-fos表达产物:Fos蛋白阳性的神经元进行计数)的改变,探讨外周神经损伤再生与痛觉过敏的关系.方法 雄性Wistar大鼠40只,体重180～200g,随机分为坐骨神经血管钳挤压损伤组(A组)和假手术组(B组),每组20只.前者分离出右侧坐骨神经后于神经中段用止血钳挤压神经直到成为透明膜状,持续30s;后者将坐骨神经于空气中暴露5min后,还复至原位.术后第18、21、24、27、30、33、36、39天重复检测大鼠行为学、机械痛阈值、TWL值.术后21、27、33、39d处死大鼠,免疫组化检测Fos蛋白表达.结果 A组术后各时间点的累积疼痛评分均高于B组(P＜0.05),但A组内各时间点间无差异.A组术后21d后机械痛阈值和TWL均低于B组(P＜0.05).A组术侧L4-5.脊髓背角浅层Fos蛋白阳性反应神经元计数大于B组(P＜0.05).A组39d的机械痛阈和TWL值均大于21d(P＜0.05),但Fos蛋白阳性反应性神经元计数无显著差异.结论 坐骨神经挤压模型中外周神经损伤再生过程诱发脊髓背角浅层c-fos表达,同时出现再生神经支配区域的机械痛觉过敏和疼痛相关行为.

c-fos expression in cornu dorsale medullae spiimlis in crush injury of sciatic nerve in rats

Objectives A rat model sciatic nerve crush injury was reproduced in rat,and behavioral changes,pain threshold,thermal withdrawal latency(TWL)and the changes in c-fos expression in cornu dorsale medullae spinalis were examined,and the relationship between peripheral nerve regeneration and hyperpathia was explored.Methods 40 male Wistar rats weighing 180-200g were randomly divided into sciatic nerve injury group(group A,n=20)and sham-operation group(group B,n=20).The right sciatic nerve of rats in group A was crushed with a hemostat in the middle of the nerve for 30 seconds,until the nerve appeared translucent.The right sciatic nerve of rats in group B was only exposed without crush injury under the same anesthesia.Behavioral response,pain threshold and TWL were assessed on 18,21,24,27,30,33,36 and 39d after operation.c-fos expression was examined immunohistochemically on 21,27,33 and 39d after operation after rats were euthanized.Results The cumulative pain scores of group A were higher than those of group B at every time point(P<0.05),while no significant difference existed between each time points in group A.The pain threshold and TWL of group A on 21d after operation was lower than those of group B(P<0.05).The count of neurons count with positive Fos protein in cornu dorsale medullae spinalis L4-5 of group A was higher than that of group B(P<0.05).As for pain threshold and TWL,more striking contrast between the values of 21d and 39d after operation existed in group A compared with that in group B(P<0.05),while no significant difference was found between the c-fos expression level on 21d compared with that of 39d after operation.Conclusions The regeneration of injured peripheral nerve may induce the c-fos expression and also hyperpathia and changes in pain-related behavior.