P2X7受体介导的PI3K/AKT/mTOR信号通路在慢性痛与抑郁共患中的调控作用研究

Pain and depression are two highly comorbid disorders in both chronic pain and depression patients, suggesting that they might share a common neurological mechanism. It has been reported that genetically knocking out P2X7 gene could relieve both painful responses and depressive syndromes in animal models. Out preliminary data also confirmed that systemically blocking P2X7 receptor by a selective antagonist increased both mechanical and thermal pain thresholds, and alleviated their depressive-like behavior. On the other hand, it has been reported that PI3K/AKT/mTOR signal pathway is involved in both chronic pain and depression, indicating that P2X7R-mediated PI3K/AKT/mTOR signaling pathway might play a key role in pain and depression. Therefore, using behavioral tests, electrophysiological techniques, molecular and cellular biological techniques, our project plans to study the effect of P2X7R-mediated PI3K/AKT/mTOR signaling pathway on comorbidity of chronic pain and depression, in order to provide evidence for understanding the mechanism of comorbidity of chronic pain and depression.

在慢性痛与抑郁症患者中，疼痛和抑郁的共患比例高，提示慢性痛和抑郁可能有共通的神经病理机制。已有研究表明敲除 P2X7 受体基因可减轻疼痛反应，改善抑郁样行为。我们的前期结果也证实，系统给予P2X7 受体拮抗剂可改善慢性痛和抑郁共患模型小鼠的疼痛反应和抑郁样行为。其次，研究指出PI3K/AKT/mTOR 通路与两者均有关联，提示P2X7 受体介导的 PI3K/AKT/mTOR通路可能是慢性痛与抑郁症发病的关键调控因素。因此，本项目将整合行为学实验、电生理技术、分子和细胞生物学技术，从整体、细胞、分子和神经环路水平研究P2X7受体介导的 PI3K/AKT/mTOR信号通路在慢性痛与抑郁共患中的调控机制，为深入理解两者的发病和共患机制提供理论依据。

在慢性痛与抑郁症患者中，疼痛和抑郁共患的比例高，提示慢性痛和抑郁可能有共通的神经病理机制。本研究我们使用单次足底注射完全弗氏佐剂（CFA）的方法作为慢性痛模型，28天慢性不可预见性应激模型（chronic unpredictable mild stress, CUMS）作为抑郁症小鼠模型，同时注射CFA和使用CUMS处理的动物作为慢性痛与抑郁共患模型（CFCU）。通过使用von Frey test和Hargreaves test检测模型动物的机械痛阈值和热痛阈值，使用强迫游泳实验（Forced swimming test, FST）和糖水偏好实验 (Sucrose preference test, SPT) 检测模型动物的抑郁样行为，我们发现疼痛和抑郁存在共患现象：慢性痛可诱发抑郁行为，也可加剧CUMS导致的抑郁症状；持续的应激（CUMS）不仅可以诱发抑郁行为，也使疼痛加剧。通过药理阻断（腹腔注射P2X7拮抗剂）或靶向沉默（rAAV-U6-P2X7 shRNA-CMV-mCherry）海马P2X7受体，我们发现系统阻断或靶向沉默P2X7受体可减轻疼痛及抑郁样行为，提示了P2X7受体是慢性疼痛和抑郁共患的必要因素。除此之外， 通过注射P2X7R激动剂或过表达P2X7能够诱发正常小鼠出现疼痛和抑郁行为，证明了上调P2X7受体是疼痛和抑郁行为发生的充分因素。通过研究它的下游通路，我们发现PI3K/AKT通路激活主要参与抑郁而不是疼痛，而Pannexin可能参与P2X7受体介导的慢性痛和抑郁共患。本研究提示了ATP受体P2X7R可能是慢性痛和抑郁共患的关键因素，抑制P2X7R可能是治疗慢性痛和抑郁的潜在靶标。