脊髓背角内吗啡肽2参与形成带状疱疹后神经痛的机制研究

Postherpetic neuralgia (PHN), the most common complication of herpes zoster (HZ), plays a major role in decreased life quality of HZ patients. However, there is still no ideal explanation on the neural mechanisms underlying PHN. Previous studies for PHN maily focused on the degeneration and inflammation of peripheral nerve, whereas some recent studies showed that peripheral nerve injury may not be the main etiological factor, and pathological changes in the central nervous system (brain and spinal cord) may largely contribute to PHN. Here, our preliminary experiments showed that endomorphin2 (EM2) in spinal dorsal horn was significantly decreased in a PHN rat model, and intrathecal injection of EM2 had desirable antinociceptive effect. However, the cause of the decrease of EM2 and the mechanism of EM2 induced analgesia are still unclear. Our research group plans to use PHN rat model to make further study. The detailed schedules are as follows: ①to clarify the causes of the decrease of EM2 in spinal dorsal horn by using morphological methods; ②to show the synergistic antinociceptive effects between EM2 and widely used analgesics by using isobolographic analysis; ③to elevate the expression level of EM2 in spinal dorsal horn by viral vector transfection and to evaluate the analgesic effects; ④to explore the molecular mechanism of EM2 mediated analgesia by behavioral test and patch clamp whole cell recoding. The results of the present study will show the detailed pathophysiological mechanism underlying PHN in a new way, and provide original theories for the diagnosis and treatment of PHN.

带状疱疹后神经痛（PHN）慢性迁延，经久难愈，是带状疱疹最严重的并发症，然而其机制尚不明了。以往认为外周神经纤维变性和炎症是PHN的主要原因，然而最近报道PHN的发病与中枢神经系统（脊髓和大脑）也有密切关系。本项目组前期研究表明：在PHN大鼠模型，脊髓中枢水平内吗啡肽2(EM2)的表达显著减少，且鞘内给予EM2具有明显镇痛作用。然而EM2减少的原因以及EM2的镇痛机理尚不清楚。本研究将以PHN大鼠模型为工具，以脊髓背角为靶点，采用多种实验方法开展以下工作：①利用形态学的方法查明脊髓EM2减少的原因；②分析EM2与各种常用镇痛药联合使用的协同镇痛作用；③利用重组病毒载体上调脊髓背角EM2的表达，同时观察镇痛作用；④利用行为学和膜片钳相结合的方法深入探索EM2镇痛的胞内分子机理。本研究的相关结果从全新的角度揭示PHN的病理生理机制，为PHN的诊疗提供新的理论依据。

带状疱疹后神经痛（PHN）慢性迁延，经久难愈，是带状疱疹最严重的并发症，然而其机制尚不明了，阐明其发病机制和研发新型特效的镇痛药物迫在眉睫。以往认为外周神经纤维变性和炎症是PHN的主要原因，但最近一些研究表明外周神经病变不能完全解释PHN的发生和发展, PHN的发病与中枢神经系统（脊髓和大脑）也有密切关系。本项目组前期研究表明：在PHN大鼠模型，脊髓中枢水平内吗啡肽2(EM2)的表达显著减少，且鞘内给予EM2具有明显镇痛作用。然而EM2减少的原因以及EM2的镇痛机理尚不清楚。本研究以PHN大鼠模型为工具，以脊髓背角为靶点，采用多种实验方法开展了以下工作：①利用形态学和HPLC的方法查明了脊髓EM2减少的原因；即PHN大鼠背根神经节EM2阳性神经元及EM2含量显著减少，最终导致经中枢突运输到脊髓背角的EM2显著减少。②观察到EM2与吗啡等各种常用镇痛药联合使用具有协同镇痛作用；这样可以在增强药效的同时减少药物用量和副作用。③构建稳定表达EM2的重组病毒载体；把该载体导入背根神经节，观察到对PHN具有镇痛作用；该方法旨在利用分子生物学的方法对PHN产生持久的镇痛作用。④利用行为学和膜片钳相结合的方法观察到EM2作用于突触前和突触后所产生的抑制性效应；即当痛觉信息从外周传递到脊髓背角时，EM2与SP共同释放，一方面EM2结合于突触前膜的MOR，抑制SP的释放，另一方面EM2结合于突触后膜的MOR抑制SP的突触后效应，最终实现镇痛效应。本研究的相关结果从全新的角度揭示了PHN的病理生理机制，为PHN的诊疗提供了新的理论依据。