鞘内注射GDNF对神经病理性疼痛大鼠脊髓水平p-Akt表达的影响

EFFECTS OF GLIAL CELL LINE-DERIVED NEUROTROPHIC FACTOR ON THE EXPRESSION OF p-Akt IN SPINAL CORD IN A RAT MODEL OF NEUROPATHIC PAIN

目的:探讨神经病理性疼痛大鼠脊髓水平p-Akt的表达变化及鞘内给予胶质细胞源性神经营养因子(glial cell line-derived neurotrophic factor,GDNF)后对其表达的影响。方法:实验1:SD雄性大鼠分为对照组和CCI组。CCI组又分为术后1 d组(D1组)、术后3 d组(D3组)、术后7 d组(D7组)和术后14 d组(D14组)。分别于术后1、3、7、14 d测定热缩足潜伏期(thermal withdrawal latency,TWL)后处死并取其脊髓背角,采用Western blot方法测定Akt(p-Akt)蛋白表达情况。实验2:SD雄性大鼠分为对照组、D14'组、D14'+PBS组、D14'+GDNF组。与实验1相同时间点测定TWL,并于第14 d处死,取其脊髓背角,采用Western blot和免疫组化法检测p-Akt表达变化。结果:与对照组相比,CCI组大鼠TWL明显降低(P<0.01);与D14'组和D14'+PBS组相比,D14'+GDNF组大鼠TWL明显升高(P<0.01)。CCI组脊髓组织中p-Akt表达水平于术后3 d开始升高,一直持续到术后14 d(P<0.01);D14'+GDNF组p-Akt表达水平较D14'组和D14'+PBS组显著下降(P<0.05)。结论:大鼠脊髓组织中Akt信号通路可能参与了神经病理性疼痛的发生,鞘内注射GDNF减轻神经病理性疼痛与降低脊髓组织p-Akt的水平有关。

Objective：To investigate the expression of p-Akt and the effect of intrathecal injection of glial cell line-derived neurotrophic factor （GDNF） on the expression of p-Akt in the spinal cord in a rat model of neuropathic pain.Methods：Experiment 1：Male Sprague-Dawley rats were divided into control group and CCI group.The CCI group was further divided into 1 d postoperative group （group D 1）,3 d postoperative group （group D3）,7d postoperative group （group D7） and 14 d postoperative group （group D14）.The thermal hyperalgesia was assessed with thermal withdrawal latency （TWL） at 1 d,3 d,7 d and 14 d after CCI.After the determination of TWL,rats were sacrificed,and the spinal dorsal horn was collected for Western blot.Experiment 2：Male Sprague-Dawley rats were divided into control group,groupDl4＇,D14＇ combined with treatment of PBS group （D14＇＋PBS group） and D14＇ combined with treatment of GDNF group （D14＇＋GDNF group）.The TWL was determined at the same time point as the experiment 1 and the rats were sacrificed at 14d,then the dorsal horn of the spinal cord was collected for Western blot and immunohistochemistry analysis.Results：Compared with control group,the TWL of CCI group decreased significantly （P ＜ 0.01）.Compared with group D14＇ and group D14＇＋PBS,the TWL of group D14＇＋GDNF was significantly increased （P ＜ 0.01）.The expression level of p-Akt in CCI group began to increase at 3 d and sustained at a high level until 14 days after operation （P ＜ 0.01）,the p-Akt level of D14＇＋GDNF group decreased significantly compared to that of D14＇ group and D14＇＋PBS group （P ＜ 0.05）.Conclusion：The Akt signaling pathway in spinal cord may be involved in the mechanism of neuropathie pain,and the alleviation of neuropathic pain by intrathecal administration of GDNF is associated with a decrease ofp-Akt level in spinal cord.