大鼠坐骨神经慢性压迫后脊髓背角GCH1基因表达与疼痛的关系

PAIN AND EXPRESSION OF GCH1 GENE IN SPINAL DORSAL HORN FOLLOWING THE SCIATIC NERVE CHRONIC CONSTRICTION INJURY

目的：探讨大鼠坐骨神经慢性压迫（chronic constriction injury,CCI）后,脊髓背角内三磷酸鸟苷环化水解酶1（GTP cyclohydrolase 1,GCH1）基因的表达变化与神经病理性疼痛产生的关系。方法：wistar大鼠64只被随机分为CCI组和Sham组,每组32只。对CCI组大鼠行右侧坐骨神经结扎;建立CCI模型,Sham组仅暴露坐骨神经不结扎,于术前1天及术后1、3、7、10、14、21、28天测定大鼠机械痛阈值,并分别在术后3、7、14、28天取腰4-6段脊髓,进行免疫组化和Western Blotting检测,观察脊髓背角GCH1表达的变化情况。结果：CCI组大鼠术后各时间点后肢机械痛阈值均显著低于Sham组（P〈0.05）,术后第1天开始疼痛阈值便明显降低,直至术后第28天,均低于术前水平（P〈0.05）。免疫组化结果显示：CCI组大鼠术后脊髓背角神经元GCH1的表达呈先升高后降低的趋势;与Sham组相比,术后各时间点GCH1的表达均明显增高（P〈0.05）。Western Blotting检测与免疫组化结果基本一致,CCI组术后3天、7天、14天GCH1表达均高于Sham组（P〈0.05）。结论：周围神经损伤引起的痛觉过敏随脊髓背角内GCH1表达升高而增强,随其表达降低而减轻,可以认为GCH1可能参与了神经病理性疼痛的形成。

Objective： To explore the relationship between the expression of GTP cyclohydrolase 1 （GCH1） gene in spinal dorsal horn and the neuropathic pain after chronic constriction injury （CCI） of rats sciatic nerve. Methods： 64 Wistar rats were divided randomly into 2 groups, CCI group （n = 32） and sham group （n = 32）. In the CCI group, the right sciatic nerve was slightly ligated, and the sciatic nerve of the sham-operated rats was just surgically exposed. The mechanical withdrawal threshold （MWT） was measured 1 day before the operation and 1, 3, 7, 10, 14, 21, 28 days after the operation. The L4 ~ 6 segments of spinal cord were removed respectively on the 3^rd, 7^th, 14^th and 28^th days postoperatively, and the expression of GCH1 was detected by immunohistochemistry and western blotting. Results： Compared with the sham group, MWT in the CCI group was significantly decreased after operation （P 〈 0.05）. It kept a low level from the 1st day to the 14th day after the injury, then the threshold rose again. The results of immunohistochemistry showed that after chronic constriction injury, the expression of GCH1 in spinal dorsal horn first increased and then decreased, it increased significantly compared with the Sham group postoperatively （P 〈 0.05）. The results of western blotting is according with the immunohistochemistry detection, which showed that the expression of GCH1 in the CCI group increased on the 3rd, 7th,14th days postoperatively compared with the sham group （P 〈 0.05）. Conclusion： The change of pain hypersensitivity caused by peripheral nerve injury was accompanied by the expression of GCH1 in the spinal dorsal horn, so GCH 1 in the spinal cord may be involved in the generation of neuropathic pain.