GRK6通过调节D1-D3受体异聚体参与天芪平颤方治疗左旋多巴诱发的异动症机制研究

Levodopa is the most effective and commonly prescribed treatment for Parkinson’s disease (PD). Prolonged levodopa treatment is associated with development of levodopa-induced dyskinesias (LIDs), diminishing the patients’ quality of life. We found that Traditional Chinese Medicine (TCM) we used, named as Tianqi Pingchan Formula, could alleviate dyskinesias in clinical trials. However, the underlying mechanisms are not fully understood. We found that long-term levodopa administration altered the GRK6 pathway, which is related with the hyperactivity of dopamine receptors in 6-OHDA-lesioned rats. Our previous study found that D1R and D3R had a modification of subcellular distribution and a sharp increment on surface, may involved in the mechanism of LID. Accumulating evidence indicates that D1R-D3R heteromer participate in the regulation of dopamine signaling pathway in LID rats. In this research, we will explore the interaction of D1R and D3R on sriatal MSNs. We also detect the alteration of intracellular signal molecule to demonstrate the change of D1R-D3R heteromers via GRK6 pathway and Shp-2 /ERK/mTORC1 pathway. The study will further explain the mechanism of the effect of Tianqi Pingchan Formula, provide theory evidences for treatment of LID via combined Chinese and western medicine, pave the way to explore the possible new method for treating LID.

左旋多巴是帕金森病治疗最有效的药物，但长期使用产生的异动症严重影响患者的生活质量。中药可能弥补左旋多巴之不足，预防和治疗异动症。天芪平颤方是我课题组由“秘方定震丸”•《明•王肯堂•诊治准绳》化裁而来，前期临床研究发现该方对帕金森病异动症有治疗作用，但其治疗机制不甚明确。我们前期基础研究结果表明天芪平颤方可以逆转左旋多巴诱发的异动症（levodopa-induced dyskinesias，LID）大鼠纹状体GRK6降低，影响D1受体的敏感性。同时我们也发现LID大鼠纹状体D1和D3受体在细胞膜上表达增多。近期有研究报道LID大鼠纹状体D1-D3受体异聚体表达增多，激活D1直接通路。本课题拟从GRK6调节D1-D3受体异聚体表达，以及其下游Shp-2 /ERK/mTORC1信号通路角度，研究天芪平颤方治疗异动症的机制，为该方的临床应用和推广提供理论支持。

背景：左旋多巴是PD治疗最有效的药物，但长期使用产生的LID严重影响患者的生活质量。天芪平颤方益气养血、化痰息风；气血充则风痰止，肝气疏则震颤平，对帕金森病异动症有治疗作用，但其治疗机制不甚明确。.主要研究内容：本研究从GRK6调节D1-D3受体异聚体表达，以及其下游Shp-2/ERK/mTORC1信号通路角度，研究天芪平颤方治疗异动症的机制。首先明确D1R和D3R参与了LID的发生；通过免疫共沉淀、wetern blotting等技术探讨帕金森病LID大鼠模型纹状体D1R和D3R之间的相互作用，长期的L-DOPA使用是否通过D1R-D3R异聚体影响到上游及下游的信号通路。同时，制备天芪平颤方，用于探讨天芪平颤方治疗异动症涉及的分子机制。.重要结果及其科学意义：明确了D1R/D3R复合物的存在；并观察到长期的L-DOPA使用导致D1R/D3R复合物异常激活，GRK6的改变与D1R/D3R复合物在细胞表面表达变化有关，D1R/D3R的变化影响了Shp-2/ERK/mTORC1信号通路；天芪平颤方联合左旋多巴可以改善LID症状，可能与D1R/D3R复合物以及下游信号通路相关因子的异常激活有关。该研究结果为天芪平颤方的临床应用和推广提供了理论支持。