初级感觉神经元内Nogo-A调控痛觉敏化过程中TRPV1通道功能的研究

The TRPV1 channel in DRG is the key molecule for development of the heat hyperalgesia ,which results from tissue inflammation or physical injury. However, its blocker or antagonist have obvious side effects as the analgesics. Nowadays the study of the modulation of TRPV1 channel is becoming a new field to exploit the noval analgesics. Our previous study showed that Nogo-A protein which is specifically expressed in DRG neurons dramatically encreased at the beginning stage of the inflammation pain.Interfering the function of Nogo-A significantly reduce the amount and function of the TRPV1.So we proposed the hypothesis that Nogo-A in DRG neurons participates in the inflammatory hyperalgesia through modulating the biological characteristics or function of TRPV1. This project will use multiple experimental methods on the base of fully pre-experiment and aims to first determine whether the Nogo-A protein in the DRG neurons is involved in the inflammatory hyperalgesia; then explore that whether Nogo-A is involved in hyperalgesia through modulation of biological characteristics and functions of TRPV1. This project attempt to reveal a new function of Nogo-A protein, and at the same time investigate its effects on TRPV1 regulation. Accomplishment of this project will provide a new idea for the development of new analgesic drugs with less side effect.?

背根神经节(DRG)内TRPV1通道是炎症痛等病理性痛觉敏化的关键分子，而其激动剂或拮抗剂作为镇痛药物具有明显的副作用，目前针对TRPV1的调控机制的研究成为镇痛药开发的重要方向。我们前期研究发现，特异性表达于DRG神经元中Nogo-A 蛋白在炎症痛的初期即迅速增加，干预Nogo-A的功能可快速降低炎症刺激所致DRG中TRPV1含量的升高，消弱TRPV1功能，缓解热痛觉敏化。据此，提出"DRG中的Nogo-A通过调控TRPV1生物学特性及功能参与炎症痛觉敏化"的科学假说。围绕该假说，本项目拟采用多种研究手段，在分子、细胞和整体动物水平，首先确定DRG 神经元内的Nogo-A 蛋白参与了痛觉敏化，继而探讨其通过影响TRPV1的表达或功能参与痛敏过程，试图在揭示Nogo-A 蛋白新功能的同时，探讨其对TRPV1的调控作用，为设计开发特异性的镇痛药提供新的思路，具有重要的理论意义和实际应用前景。

Nogo-A蛋白是一种轴突生长抑制因子，其特异性地高表达于成体动物的初级感觉神经元中，而关于Nogo-A在感觉传导过程中的作用一直没有被揭示。本项目以CFA诱导的炎症痛为模型，采用免疫荧光染色、Western blot、钙成像、行为学、大鼠基因敲除、RNA干扰等实验方法研究了Nogo-A在炎症热痛的产生过程中的作用，发现：1）在炎症热痛过程中Nogo-A在背根神经节中的含量显著增高， 敲除Nogo-A蛋白或拮抗其作用显著性降低大鼠的炎症热痛敏；2）Nogo-A在炎症热痛过程中通过LIMK/Cofilin途径对微丝具有促进聚合的作用。3）炎症热痛敏过程中微丝聚合状态的增加促进了痛觉整合器TRPV1的蛋白表达和功能维持。4）在拮抗Nogo-A的作用后，炎症痛过程中的TRPV1迅速被蛋白酶calpain降解。此项目的研究结果发现Nogo-A在炎症热痛敏过程中通过微丝骨架的聚合作用调控了TRPV1通道的功能。该实验结果不但揭示了炎症热痛的一种具有重要作用的调控因子，也发现了Nogo-A蛋白的一种重要的功能。对镇痛药的开发提供了一种新的思路，具有一定的临床应用前景。