DRD2-Ca2+信号通路对PTSD所致学习记忆障碍的调控作用及机制研究

Posttraumatic Stress Disorder（PTSD）has become an important disease due to its high morbidity,long course of disease and bad curative effect.One of the main symptoms of PTSD is learning/memory dysfunction.Up to now, its underlying pathophysiology remains ambiguous. Present researches show that synaptic plasticity （LTP/LTD）were the basis of cells level for learning and memory, The Ca2+-CaM-CaMKIIα is the key signal pathway for regulating the LTP/LTD .Dopamine activity are closely associated with learning and memory dysfunction.The dopamine receptor D2 is a member of the D2-like family of dopamine receptors, it was well documented that DRD2 in amygdala could regulate the Ca2+ concentration of intra-cellular by one or more pathway, so it may be involved with LTP/LTD development.The anomalous DRD2 pathways is the key mechanism of learning and memory dysfunction in PTSD, so we suppose that the decreased DRD2 may lead to calcium concentration diversify and activate the PLC signal pathway, and induce LTP/LTD activation, finally lead to learning and memory dysfunction in PTSD. Ours preliminary experiment proved DRD2 mRNA decreased in PTSD-SPS rat. To validate this suggestion, we try to identify the role of DRD2 expression during learning and memory dysfunction of PTSD, to understand the effect and significance of DRD2 in PTSD, to clarify the molecular mechanism of DRD2 regulation in the learning and memory dysfunction of PTSD . This study may be conduce to reveal the pathogenesis of PTSD, and will support the prevent and treatment of learning and memory dysfunction in PTSD.

创伤后应激障碍（PTSD）严重危害人类健康，学习记忆障碍是PTSD的核心症状，但发生的分子机制尚未完全阐明。研究表明，杏仁核是调控PTSD症状的关键核团，突触可塑性是学习记忆的细胞学基础，钙离子信号通路是调节突触可塑性的关键通路。而DRD2可以通过一条或多条途径调节细胞内钙离子浓度，且DRD2基因多态性在PTSD的发生中具有重要作用。因此，我们推测DRD2表达变化可导致胞内钙离子浓度变化，并通过调控突触可塑性，在PTSD的学习记忆障碍发生中发挥重要作用。本项目拟采用前脑特异性DRD2基因敲除小鼠、转基因小鼠及PTSD小鼠动物模型，通过脑片电生理、整体行为学、分子生物学及免疫组化等技术，从分子、细胞和整体水平探讨DRD2表达变化致胞内钙离子浓度变化并触发ERK信号通路，以及对突触可塑性的调节作用，试图揭示DRD2在PTSD所致学习记忆障碍中的作用及分子机制，为PTSD的诊断及治疗提供新靶点。

本项目严格按照预期计划进行，顺利完成了所有的预期研究计划，并充分利用现有的动物模型，同时对野生型、DRD2转基因鼠和DRD2条件性敲除鼠的前额、海马和杏仁核三个部位进行研究，以便比较分析DRD2及Ca2+信号通路分子在PTSD所认知功能障碍的作用及机制。采用海马特异性DRD2基因敲除小鼠、DRD2过量表达的转基因小鼠及野生型C57小鼠，用幽闭电刺激所致的PTSD动物模型研究DRD2在前额、海马和杏仁核三部位对Ca2+信号通路相关分子的表达调控。研究发现，DRD2-Ca2+通路中主要是Ca2+通过调控DRD2的表达或活性而进一步调控下游信号通路；明确了DRD2在前额、海马和杏仁核中对突触可塑性与学习记忆障碍的调节环路略有差异，与认知有关的分子主要在杏仁核，其次是海马，最后才是前额；筛选了能明显改善PTSD所致学习记忆障碍的关键分子，发现DRD2拮抗剂能改善PTSD所致的神经认知功能状态。该研究结果为揭示PTSD发生发展的分子机制及临床PTSD早期诊断及治疗的新靶点提供了研究基础。