脊髓G蛋白耦联受体激酶2在大鼠持续性术后痛中的作用

Role of spinal G protein- coupled receptor kinase 2 in persistent postoperative pain in rats

目的研究脊髓G蛋白耦联受体激酶2（Gprotein-coupled receptor kinase2，GRK2）在大鼠持续性术后痛中的作用。方法鞘内置管成功的雄性SD大鼠60只，采用随机数字表法分为6组（每组10只）：假手术组（I组）、假手术＋溶媒二甲基亚砜（dimethyl sulfoxide，DMSO）组（Ⅱ组）、假手术＋GRK2降解抑制剂MDL28170组（Ⅲ组）、皮肤／肌肉切口和牵拉（skin／muscle incision and retraction，SMIR）组（Ⅳ组）、SMIR＋DMSO组（V组）、SMIR＋MDL28170组（Ⅵ组）。应用Yaksh法鞘内置管；采用Flatters法制备大鼠SMIR模型；各组大鼠分别于术前1d（To）、术后3d（T1）、术后7d（T2）、术后14d（T3）、术后21d（T4）用yonFrey细丝法测定机械刺激缩足阈值（paw withdrawal mechanical threshold，PWMT）；于T3时刻行为学测定后各组随机抽取4只大鼠处死，取L4～L6节段脊髓组织，采用Westernblot法检测脊髓GRK2的表达。结果与Ⅰ组比较，Ⅳ组和V组T1-T4时PWMT明显降低（P〈0．05），Ⅵ组T1～T3时PWMT明显降低（P〈0．05）；T1～T4时，与Ⅳ组比较，Ⅵ组PWMT明显升高（P〈0．05）。与Ⅰ组比较，Ⅳ组和V组大鼠脊髓GRK2表达明显下调（P〈0．05）；与Ⅳ组比较，Ⅵ组大鼠脊髓GRK2表达明显上调（P〈0．05）。结论脊髓GRK2表达水平下调与大鼠SMIR持续性术后痛的发生、发展有关。

Objective To investigate the role of spinal G protein-coupled receptor kinases 2 （GRK2） in persistent postoperative pain after skin/muscle incision and retraction （SMIR） in rats. Methods Sixty male SD rats in which intrathecal catheter were successfully implanted were divided randomly into 6 groups （n=10）： sham operation group （group Ⅰ ）, sham ＋ dimethyl sulfoxide （DMSO） group （group Ⅱ）,sham＋MDL28170group （group Ⅲ）,SMIRgroup （group Ⅳ）, SMIR＋DMSO group （group Ⅴ）, SMIR＋MDL28170 group （group Ⅵ）. A PE-10 catheter was inserted into the subarachnoid space （intrathecal）. A rat model of persistent post-operative pain was established with SMIR. Pain behavior was assessed with yon Frey filament test and was quantified with paw withdrawal mechanical threshold （PWMT） 1 d before operation （T0） and 3 d （T1）, 7 d （T2）, 14 d （T3） and 21 d （T4） after operation. Four rats in each group were sacrificed at T3, the L4-L6 segments of the spinal cord were obtained to determine the protein levels of GRK2 with Western blot assay. Results Compared with group Ⅰ, the PWMT was significantly decreased at T1-T4 in group Ⅳ and group Ⅴ （P〈0.05）, and at T1-T3 in group Ⅵ （P〈0.05）. Compared with group Ⅰ , the protein levels of spinal GRK2 was down-regulated at T3 in group Ⅳ and group Ⅴ （P〈0.05）. Compared with group Ⅳ, the spinal GRK2 was upregulated at T3 in group Ⅵ （P〈0.05）. Conclusions The down-regulation of spinal GRK2 may be involved in the development and maintenance of persistent postoperative pain in rats following SMIR.