TREK-1双孔钾离子通道拮抗效应与抗抑郁治疗快速起效分子机制研究

The therapeutic effect of antidepressants usually requires several weeks after drug administration. The delayed onset of antidepressant efficacy is one of the most critical clinical issues for depression treatment. The desensitization of serotonin 1A receptor (5-HTR1A) in rapheal nuclei and hippocampal neurogenesis have been found to consist with the timing of improvement of depressive syndrome after the antidepressant administration. Most recently, some studies had demostrated that blockage effect of two pore domain potassium channel TREK-1 had the rapid onset of antidepressant efficacy. However, the exact time course of TREK-1 antagnism on antidepressant efficay and its signal transduction mechanism remains unclear. The present study will investigate the time course of TREK-1 antagnism on the onset speed of antidepressant efficacy with the chronic unpredictable mild stress rat model. We will explore the effect of TREK-1 antagnism on firing rate of the 5-HT neuron in raphe nucleus in brain slices. After stereotaxic administration of the TREK-1 antagnist to raphe nucleus, the onset speed of antidepressant efficacy and the possible molacular mechanism related with cAMP-PKA signal transduction pathway will be explored. We will investigate the effects of TREK-1 antagnist on in vitro neurogenesis of rat embryonic hippocampal neural stem cells (NSCs). The CUMS rat will be also used to study the effect of TREK-1 antagnist on time course of neurogenesis in hippocampal dentate gyrus and its underlying intracellular PKMζ-MAPK signal transduction mechanisms. We expect that these studies will contribute to our understanding of the effect of TREK-1 antagnism on the onset speed of antidepressant efficacy. These experimental evidences may improve the study of screening of new durg target for deperassion treatment.

抗抑郁剂延迟起效是抑郁症临床治疗最突出的难题之一。研究表明中缝核5-HT能神经元放电频率的变化和海马齿状回神经再生与抗抑郁剂起效时程一致，TREK-1双孔钾离子通道拮抗作用可能具备早期抗抑郁效应，但是其确切时效关系和信号转导机制尚未明了。本研究将首先利用CUMS大鼠评估TREK-1抑制作用与抑郁行为改善的时效关系；其次，结合离体中缝核脑片和在体中缝核定向给药方法研究TREK-1抑制效应对5-HT能神经元放电频率的影响，及其与cAMP-PKA信号转导通路的可能关系；第三，探讨TREK-1通道抑制效应对体外培养胎鼠海马神经干细胞再生的影响；利用CUMS大鼠研究TREK-1通道拮抗剂对海马神经再生影响的时效影响，并探讨PKMζ-MAPK信号转导通路的可能作用；最后综合分析TREK-1抑制效应在抗抑郁起效速度机制中的作用，为寻找抑郁症更为有效的治疗措施提供新的实验依据。

本项目主要探讨TREK1通道拮抗剂快速抗抑郁作用及其机制，主要发现，筛选并鉴定的TREK通道拮抗剂-SID1900敏感性、特异性均较高，可快速、持续改善CUMS大鼠抑郁样行为，其可能机制包括，SID1900作为小分子化合物可迅速透过血脑屏障、显著增高中缝核5-HT能神经元放电频率即增加5-HT传递效率、并通过调节5-HTR1A介导的PKA-CREB-BDNF信号传导通路发挥其抗抑郁作用；另外，SID1900可显著提高海马DG区神经前体细胞增殖、向神经元转化和抗神经细胞凋亡从而增加海马神经再生以发挥抗抑郁效能。