多巴胺信号通路介导机械通气诱发术后谵妄的作用机制研究

Postoperative delirium (POD) in critically ill patients is the focus of ongoing discussion in the field of anesthesiology and perioperative medicine. We previously demonstrated that on this background of prior surgery, mechanical ventilation is among the most common triggers of POD. The current study shows that high-pressure ventilation triggers hippocampal apoptosis induced delirium by vagal and dopaminergic activity. However, pathogenesis of MV raised surgery-induced delirium is poorly understood, including early neurological effects related to MV and dopaminergic pathways. We hypothesized that mechanical ventilation could directly cause POD via dopaminergic neurotransmitters. To test this hypothesis, the main objective of the present study was to investigate the consistency and timeliness of dopamine is released instantaneously in POD induced by mechanical ventilation. Furthermore, activation and inhibition of ventral tegmental area (VTA) dopaminergic neurons were implicated in memory and social function through optogenetic investigation, the phenotype of animal behaviors at different points of releasing dopamine to determine how the cognitive deficits expressed as POD happened. Finally, we will further deepen the research and reveal the target and internal mechanism of dopamine receptor signaling in POD. MV promoting POD should be considered most comprehensively addressed in the treatment strategy.

术后谵妄（POD）是目前麻醉与围术期医学关注的热点问题。申请人前期研究发现：手术启动炎症反应作为基础，机械通气的干预是POD发生的诱发因素。目前的研究提示，高气道压力机械通气可能通过激活迷走神经通路，导致多巴胺能神经递质释放，从而诱发谵妄。但机械通气是否通过激活多巴胺受体信号通路诱导POD尚不清楚。本项目将在前期研究和预实验基础上，观察多巴胺瞬时释放与机械通气诱导POD的时效一致性；同时，应用光遗传学技术揭示中脑腹侧被盖区（VTA）多巴胺能神经元兴奋或抑制后的动物行为学反应的整体表现，阐明谵妄发生过程中多巴胺不同释放时点的动物行为学表型，并揭示分子机理。本项目研究将为POD的防治提供新的理论基础和靶点。

围手术期谵妄和认知功能障碍的发生增加术后死亡率，延长住院时间，是舒适化医疗和围术期快速康复亟待解决的问题。机械通气的肺脑交互学说集中在血脑屏障通透性增加，外周炎症因子迁移至中枢，激活小胶质细胞；外周机械刺激经迷走神经传入孤束核冲动增加，神经递质释放异常导致谵妄发生。然而，具体机制仍未阐明清楚。文献报道单纯机械通气动物模型中，迷走-多巴胺通路激活引起海马神经元凋亡，导致c-fos基因激活，dysbindin-1C表达增强。多巴胺能的神经传递主要由多巴胺D1和D2受体介导，迷走神经信号冲动传入中枢神经系统与多巴胺受体信号通路密切相关。因此，本项目提出假说：神经递质释放异常诱导脑代谢平衡紊乱，诱发皮层兴奋与抑制失衡是长时间机械通气后谵妄发生的主要原因，多巴胺受体信号通路调控脑代谢介导了机械通气诱发的谵妄。. 本研究首先观察机械通气诱发谵妄的动物行为学在时间进展中的变化趋势，揭示了长时间机械通气，激活迷走神经多巴胺转运体DAT功能，微透析检测大脑皮层多巴胺递质含量，与谵妄发作呈时效性关系。离体脑片电生理结果提示多巴胺诱发皮层锥体神经元兴奋性显著增强。其次，通过多巴胺能神经元兴奋或抑制后的动物行为学的整体表现，明确了谵妄发生过程中多巴胺释放时点的动物行为学表型。最后，观察多巴胺受体拮抗剂SCH-23390、氟哌啶醇和激动剂SKF38393、罗替戈汀对机械通气小鼠DRD1和DRD2信号通路的影响，证实了机械通气后1d时小鼠大脑皮层DRD1信号通路激活，神经元凋亡增加，3d时炎症小体表达增加，IL1-β释放增加，M1型小胶质细胞激活；同时机械通气诱导小鼠杏仁核DRD2受体激活，通气结束后不同时点ATP含量震荡变化，PET提示通气结束1d时糖代谢显著增加，3d时糖代谢显著降低。本项目从 “机械通气患者术后谵妄发生”这一临床问题出发。行为学层面，明确多巴胺瞬时释放与谵妄发作的时效性关系。神经元层面，揭示多巴胺能神经元兴奋或抑制后的动物行为学的整体表现。分子机制层面，揭示小鼠不同脑区多巴胺受体DRD1和DRD2信号通路在机械通气诱发谵妄中的作用机制，阐明了肺脑交互的迷走神经递质传导通路，为临床谵妄的治疗提供了理论依据。