Fu Qiaochu, Li Hongyi, Zhu Zhuanxu, Li Wencui, Ruan Zhihua, Chang Ruijie, Wei Huixia, Xu Xueqin, Xu Xunliang, Wu Yanqiong
Department of Anesthesiology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
Department of Anesthesiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
Front Mol Neurosci. 2024 Aug 30;17:1417567. doi: 10.3389/fnmol.2024.1417567. eCollection 2024.
Neuropathic pain (NP) conditions arising from injuries to the nervous system due to trauma, disease, or neurotoxins are chronic, severe, debilitating, and exceedingly difficult to treat. However, the mechanisms of NP are not yet clear. Here we explored the role of Dock4, an atypical Rac1 GEF, in the development of NP.
Mechanical allodynia was assessed as paw withdrawal threshold by a dynamic plantar aesthesiometer. Immunofluorescence staining was conducted to investigate the expression and localization of Dock4, Rac1 and GluN2B. Quantitative analysis of Dock4, Rac1 and GluN2B were determined by qRT-PCR and Western blot assay. Spontaneous excitatory and inhibitory postsynaptic currents in spinal cord slices were examined using whole cell patch clam. Dendritic spine remodeling and synaptogenesis were detected in cultured dorsal spinal neurons.
We found that SNL caused markedly mechanical allodynia accompanied by increase of Dock4, GTP-Rac1and GluN2B, which was prevented by knockdown of Dock4. Electrophysiological tests showed that SNL facilitated excitatory synaptic transmission, however, this was also inhibited by Dock RNAi-LV. Moreover, knockdown of Dock4 prevented dendritic growth and synaptogenesis.
In summary, our data indicated that Dock4 facilitated excitatory synaptic transmission by promoting the expression of GluN2B at the synaptic site and synaptogenesis, leading to the occurrence of NP.
由创伤、疾病或神经毒素导致的神经系统损伤所引起的神经性疼痛（NP）是慢性、严重、使人衰弱且极难治疗的。然而，NP的机制尚不清楚。在此，我们探究了一种非典型Rac1鸟苷酸交换因子Dock4在NP发生过程中的作用。
通过动态足底测痛仪将机械性异常性疼痛评估为爪部撤离阈值。进行免疫荧光染色以研究Dock4、Rac1和GluN2B的表达及定位。通过qRT-PCR和蛋白质免疫印迹法对Dock4、Rac1和GluN2B进行定量分析。使用全细胞膜片钳检测脊髓切片中的自发性兴奋性和抑制性突触后电流。在培养的背根脊髓神经元中检测树突棘重塑和突触形成。
我们发现坐骨神经结扎（SNL）导致明显的机械性异常性疼痛，并伴有Dock4、GTP-Rac1和GluN2B的增加，而Dock4的敲低可阻止这种增加。电生理测试表明SNL促进了兴奋性突触传递，然而，Dock RNAi-LV也可抑制这种传递。此外，Dock4的敲低阻止了树突生长和突触形成。
总之，我们的数据表明Dock4通过促进突触部位GluN2B的表达和突触形成来促进兴奋性突触传递，从而导致NP的发生。
