基于食蟹猴社会隔离抑郁模型探讨磷脂酶D1在抑郁症发生中的作用

Major depression (MDD) is a chronic and debilitating mood disorder which affects public health seriously. However the pathogenic mechanism still remains unclear. Thus a new angle into MDD could be a promising breakthrough.Previously we have successfully build macaca fascicularis social isolation depression model. By approaching of proteomics and metabolomics methods, lipid metabolism disorder was found in blood and cerebrospinal fluid of depressed macaca fascicularis. Moreover, compared with control group, phospholipase D1 decreased significantly in hippocampus of treatment group.There were very limited researchs on phospholipase D1 and MDD, only two articles reported inconsistent results of abnormal expression level of phospholipase D1 in rat depression models. So far there is still no MDD clinical research on phospholipase D1.Phospholipase D1 is able to hydrolyze phosphatidyl choline (PC), which subsequently produces choline (Cho) and phosphatidic acid (PA). PA is an important second messenger in cells, which combines to rapamycin target protein (mTOR) signaling pathway. mTOR pathway involving in the pathogenesis of depression has been very crucial research topic currently.Therefore, we propose the hypothesis that phospholipase D1 might be associated with depression through mTOR pathway.This research intends to use macaca fascicularis social isolation depression model as study carrier. By detecting phospholipase D1 and mTOR pathway in key brain regions, we try to explore the role of phospholipase D1 in MDD, thus further clarifying the pathogenesis of MDD and providing theoretical basis for the development of new drug targets.

抑郁症严重影响公共健康，发病机制不清。申请人前期已成功构建社会隔离食蟹猴抑郁模型，并采用蛋白组学及代谢组学研究发现，抑郁猴模型外周及中枢神经系统脂质紊乱。与正常猴相比，磷脂酶D1在抑郁猴海马中表达水平显著下调。鉴于既往研究同时表明，磷脂酶D1在抑郁大鼠模型中亦出现表达异常，提示磷脂酶D1可能在抑郁症的发生中发挥相应作用。磷脂酶D在体内可水解磷脂酰胆碱 (PC)产生胆碱（Cho）和磷脂酸（PA），后者作为细胞内重要第二信使，可结合雷帕霉素靶蛋白（mTOR）信号通路，与神经精神疾病的发生相关。因此，我们提出假说：在猴抑郁模型中，磷脂酶D1可能通过mTOR通路参与抑郁症的发生。本课题组拟采用最接近人类的模式动物食蟹猴社会隔离抑郁模型为研究载体，检测关键脑区磷脂酶D1及下游mTOR通路的变化，探讨磷脂酶D1在抑郁症发生中的作用，以期进一步阐明抑郁症发病机制，为开发新的药物靶点提供理论依据。

抑郁症是复杂的精神疾病，既往研究表明SSRI类药物可通过BDNF/TrkB/Erk/Creb通路发挥抗抑郁作用，PLD1是连接BDNF/TrkB通路和Erk/Creb通路的分子桥梁，结合前期研究发现抑郁猴海马PLD1表达下调，我们提出假说SSRI可能通过PLD1介导上调BDNF/TrkB/Erk/Creb通路活性发挥抗抑郁作用。我们采用6只社会隔离抑郁猴模型和6只对照猴，随机分配至空白对照或舍曲林组，进行16周治疗后予以行为学评价，并采用PCR、WB及转基因等手段在体内和体外两个层次检测海马脑区PLD1表达，BDNF/TrkB/Erk/Creb通路及Erk/mTOR通路活性。统计学采用双因素方差分析方法。实验结果显示抑郁猴海马BDNF，TrKB及PLD1表达量显著下降（p<0.05），同时ERK1/2磷酸化和CREB磷酸化水平下调（p<0.05），经过舍曲林治疗上述指标上调，同样抑郁猴海马突触蛋白PSD95和SYP也有上述类似表现。而在非抑郁猴中上述指标没有显著差异性。而在海马神经元中沉默PLD1后，舍曲林不能恢复Erk/Creb和Erk/mTOR通路活性。结论提示SSRI可能通过PLD1介导作用于Erk/Creb和Erk/mTOR通路上调海马突触蛋白（PSD95和SYN）发挥抗抑郁作用。