胶质细胞源性神经营养因子在大鼠神经病理性疼痛模型中的作用及机制研究

目的 探讨胶质细胞源性神经营养因子（GDNF）通过PINK1/Parkin信号通路对大鼠神经病理性疼痛的作用及其机制。方法 将大鼠按随机数字表法分为Sham组、NP组和GDNF组。对大鼠的一般情况和行为学进行观察和测定；透射电镜观察大鼠脊髓；Western blotting法观察大鼠脊髓组织中PINK1和Parkin蛋白表达。结果 Sham组大鼠的情况良好；与Sham组比较，术后NP组大鼠侧肢体后爪有内收的现象，偶有大鼠跛行；GDNF干预后大鼠的情况明显好于NP组大鼠。3组大鼠机械缩足反射阈值（MWT）和热痛阀值（TWL）在坐骨神经压榨性损伤（CCI）的阈值无明显的变化（P >0.05）；术后3 d、7 d和14 d的MWT和TWL比较，NP组大鼠较Sham组大鼠降低（P <0.05）；NP组大鼠脊髓组织中完整自噬小体双膜结构较少，线粒体分别出现肿胀甚至空泡变性，还有大量的线粒体消失不见，少数出现与溶酶体融合；经过GDNF干预后，GDNF组大鼠在各个时间的MWT和TWL较NP组大鼠升高（P <0.05）；GDNF组大鼠脊髓组织中少见自噬小体双模结构，线粒体偶见轻微肿胀和空泡变性，未见溶酶体融合。NP组大鼠脊髓组织中的PINK1和Parkin蛋白表达较Sham组升高（P <0.05）；经过GDNF干预治疗后发现，GDNF组大鼠脊髓组织中PINK1和Parkin蛋白降低（P <0.05）。结论 GDNF作用机制可能通过抑制PINK1和Parkin蛋白表达，从而有效减轻神经病理性疼痛。

Mechanism of GDNF on neuropathic pain in rats through PINK1 / parkin signaling pathway

Objective To explore the mechanism of GDNF on neuropathic pain in rats through PINK1 / parkin signaling pathway.Methods Rats were divided into three groups: sham group, NP group, GDNF group, and GDNF group. After grouping, the neuropathic pain model of rats was made by chronic compression of sciatic nerve (CCI). Firstly, the general situation and behavior of rats were observed; the number of autophagy bodies and the morphology of mitochondria in the spinal cord were compared by transmission electron microscope; the expression of PINK1 protein and parkin protein in the spinal cord were observed and compared by Western blotting.Results There were no symptoms in sham group. Slight ectropion and claudication in NP group, and the condition of GDNF group was better than NP group. There was no significant change in the mechanical pain threshold and the thermal pain threshold before CCI in the three groups (P > 0.05). In the NP group, the hind paw of the limb on the operative side showed adduction and valgus, and some rats limped (P < 0.05). Moreover, the complete autophagy body double membrane structure in the spinal cord tissue in the NP group was less, and the mitochondria swelling, vacuolation, and extreme disappearance appeared after GDNF intervention; compared with the mechanical pain threshold and thermal pain threshold of NP group, GDNF group increased significantly (P < 0.05). The spinal cord of GDNF group had few autophagic bodies with dual-mode structure, and the mitochondria occasionally showed slight swelling and vacuole degeneration, but no significant disappearance and fusion with lysosome. Compared with the protein of PINK1 and parkin in sham group, the protein in spinal cord of NP group was significantly higher (P < 0.05). After the intervention of GDNF, the protein expression of GDNF group decreased significantly (P < 0.05).Conclusion GDNF may be through inhibiting the expression of PINK1 protein and parkin protein, so as to effectively alleviate neuropathic pain.