Sonic hedgehog信号通路在神经病理性疼痛模型大鼠中的表达及其意义

Expression and significance of sonic hedgehog in neuropathic pain rat model

目的 ：观察神经病理性疼痛模型大鼠脊髓组织中（sonic hedgehog,Shh）信号通路的表达及随时间的动态变化规律,探索其在神经病理性疼痛中所发挥的作用。方法：取80只成年SD大鼠,采用随机数字表法均分为假手术组（sham operation group,Sham）与坐骨神经慢性压迫模型（chronic constriction injury of the sciatic nerve,CCI）组。CCI组（n=40）左侧坐骨神经以4.0丝线结扎,Sham组（n=40）不结扎,仅暴露左侧坐骨神经。建模后1、4、7、14、28 d分别对2组大鼠进行一般行为学观察,并测定大鼠机械缩足反射阈值（mechanical withdrawal threshold,MWT）;采用Western blot和免疫组化检测大鼠脊髓腰骶膨大部（L4-6节段）的Shh、Gli表达。结果：与Sham组相同时间点比较：CCI组术前MWT（P=0.832）差异无统计学意义,术后其余各时间点均明显降低（P〈0.01）具有统计学意义;CCI组内不同时间点比较：术后第1天MWT开始明显降低（P=0.002）,7 d达到最低值（P=0.027）,28 d仍处于较低的水平（P=0.003）。Western blot结果显示：与Sham组相同时间点比较：CCI组术后1 d大鼠脊髓腰骶膨大部Shh、Gli蛋白表达没有明显变化（P=0.215）,其余各时间点Shh、Gli蛋白表达均出现明显增加（P〈0.01）;CCI组内不同时间点比较：术后7 d Shh、Gli蛋白表达水平达到最大值（P〈0.01）,这种高水平的表达可持续到损伤后28 d（P〈0.01）。免疫组化结果显示：与Sham组比较：CCI术后第7天Shh、Gli蛋白在相应区域显示染色明显增加（P〈0.01）。结论：神经病理性疼痛的发生、发展与Shh通路的激活具有显著相关,其通路蛋白的表达第7天达到峰值,第28天仍处于较高水平。

Objective：To analyze the activation of sonic hedgehog（Shh）signaling pathways in the rat model of neuropathic pain and the dynamic changing regularity over time,and to explore the role of Shh in the neuropathic pain. Methods：Eighty adult male SD rats were randomly allocated into two groups（n =40）：chronic constriction injury of the sciatic nerve（CCI） group and sham-operated group. Right sciatic nerve was ligated by 4.0 silk suture in CCI group; rats in sham-operated group did not receive ligation and their left sciatic nerves were exposed. General behavior of the two groups were observed respectively to determine mechanical withdrawal threshold（MWT）in rats on 1,4,7,14,28 d after modeling. The expression of Shh,Gli in the spinal cord of the rat lumbosacral enlargement was analyzed using Western blot and immunohistochemistry. Results：The difference in preoperative MWT between CCI group and sham group rats was not statistical significant（P=0.832）;MWT was significantly lower at all other time points after the operation（P〈0.01）. The MWT of CCI group began to decrease on the postoperative first day（P=0.002）,then achieved a minimum on day 7（P=0.027）,and was still in lower level on day 28（P=0.003）. The protein expression of Shh,Gli in CCI group rats was not significantly changed on the postoperative first day（P=0.215）,and Shh,Gli in the CCI group were significantly increased at all other time points（P〈0.01）. The protein expression of Shh,Gli in the CCI group was unregulated on day 7 after injury with maximal expression levels（P〈0.01）,which was maintained up to at least day 28 after injury（P〈0.01）. Immunohistochemistry showed that the Shh and Gli protein displayed significantly increase in the corresponding region than the sham group on the postoperative day 7（P〈0.01）.Conclusion：Neuropathic pain can induce the expression of Shh signaling pathways. The expressions of related proteins reach the peak on day 7 and maintain the high level till day 28.