基于Uptake 2转运体抑制的元胡抗抑郁活性成分及机制研究

Depression is a chronic, recurring and potentially life-threatening illness that affects up to 20% of the population across the globe, which ranked fourth in disability-adjusted life years (DALY) listing, will claim second place by 2020. “Monoamine hypothesis of depression” has been prevailing for decades, and be supported by the action of antidepressants: agents that elevate the levels of these neurotransmitters in the brain have all been shown to be effective in the alleviation of depressive symptoms. Clearance of serotonin and norepinephrine in the synaptic cleft is composed of two independent mechanisms that is high-affinity, low-capacity “uptake 1” transporters and low-affinity, high-capacity “uptake 2” transporters. Almost all antidepressants in current clinical use are designed to block the reuptake of “uptake 1”, serotonin, norepinephrine or both, but weak or no inhibition on “uptake 2”, it might lead to onset of action of initial therapeutic effects has a substantial lag time, and fail to provide a satisfactory response in up to 50% of patients treated..In our previous work, we found alkaloids extracted from Corydalis yanhusuo W. T. Wang show inhibit effect on “uptake 2” transporter, but also some toxicity reports. We hypothesized that these alkaloids may reduce neuron and glial cells of synaptic monoamine neurotransmitter uptake through inhibiting uptake transporter 2, and show antidepressant-like effect. The aim of present project were to examined these alkaloids on “uptake 2” and “uptake 1”stably transfected cell models to evaluate the Corydalis alkaloids inhibitory potencies of transporter-mediated serotonin and /or norepinephrine uptake, then the mechanism study on synaptosomes of the inhibitory effect of NE/5-HT reuptake combined with tissue distribution and cytotoxicity test of the active alkaloid compounds. The antidepressant action on CUMS mice model for providing the evidence that the antidepressant-like effect of Corydalis alkaloids associated with “uptake 2” inhibition. It might be a novel antidepressants or significant improvements in treatment strategies utilizing existing agents.

抑郁症是一类发病率高危害大的精神疾病。抑制单胺神经递质重摄取是当今最推崇的药物治疗策略，但现有药物主要基于对uptake 1转运体的抑制，对uptake 2转运体（OCT2，OCT3，PMAT）抑制弱或无，因而起效慢、疗效差、个体差异大，故急需寻找具uptake 2抑制活性或兼具uptake 1和uptake 2抑制活性的新型抗抑郁药物。元胡总碱抗抑郁作用明确，但活性成分与作用机制不清，且因具一定的毒性限制了其长期使用。我们前期发现元胡多种生物碱对神经递质重摄取和uptake 2转运体的强抑制作用，也已发现元胡少数生物碱的强细胞毒性。本研究拟应用多种人源转基因细胞模型、脑突触小体模型，结合组织分布研究，阐明对神经递质重摄取抑制作用强、靶部位浓度高、毒性小的生物碱单体，进而应用动物疾病模型，研究活性单体的抗抑郁作用，以及与现有抗抑郁药的协同作用，为元胡抗抑郁药物的研发及机制阐明提供科学依据。

本项目基于单胺神经递质重摄取抑制的作用机制，通过构建稳定表达人uptake 1转运体的转基因细胞模型（MDCK-hDAT，MDCK-hSERT），并利用构建的细胞模型考察了元胡生物碱对uptake 2和uptake 1转运体介导的神经递质摄取的抑制作用，发现了延胡索乙素和去氢延胡索甲素对uptake 2转运体介导的神经递质摄取具有较强的抑制作用；利用小鼠脑突触小体模型验证了去氢延胡索甲素对神经递质重摄取的强抑制作用；进一步构建小鼠抑郁模型研究了活性成分去氢延胡索甲素的抗抑郁作用，并考察了其作用机制。说明去氢延胡索甲素的抗抑郁作用可能与维持脑部神经递质稳态及调节HPA轴功能有关。项目成果为元胡生物碱的抗抑郁作用研究提供了理论和实验依据。