快速型抗抑郁症制剂启动AMPA受体trafficking及增强突触可塑性途径的研究

Depression is a mental illness with high rates of incidence, relapse and suicide. The latest researches show that its pathogenesis is related to abnormal synaptic plasticity. In recent years, it has been found that various types of antidepressants, such as ketamine, can rapidly and efficiently relieve depression by possible rapid potentiation of synaptic plasticity, but the mechanism of rapid onset of the action is unknown. We speculate that the rapid increase of intracellular calcium concentration by different antidepressants in various ways initiates trafficking of AMPA receptor and potentiation of synaptic plasticity. To prove this hypothesis, several advanced techniques including in vivo shadow patch with two-photon microscopy, two-photon uncage mapping receptors and LTP induced by two-photon uncage will be used to observe the effects of ketamine, GLYX-13 and (2R, 6R)-HNK on the depressive behavior of the mice with chronic unpredictable stress (CUS) model, the morphological structure of dendrites and dendritic spines, calcium signal, trafficking of AMPA receptor and synaptic plasticity of the neurons from pre-frontal cortex (PFC) and hippocampus in CUS mice; and to observe if AP5, a NMDA receptor antagonist, Nifedipine, a voltage-gated calcium channel blockers and CPA, a inhibitor of calcium releasing from calcium store can respectively eliminate above relief effects of ketamine, GLYX-13 or (2R, 6R)-HNK on CUS mice. The research findings will potentially lead to clarify different rapidly initiatating pathways of the depressive treatment by various types of antidepressants, and to provide the theoretical evidance for the prevention and treatment of depression.

抑郁症发病率、复发率和自杀率高，最新研究表明与突触可塑性异常有关。近年发现氯胺酮等多种快速型抗抑郁症制剂能快速高效缓解抑郁症，可能都与快速增强突触可塑性有关，但启动机制不明。推测不同制剂可能通过不同途径快速启动胞内钙浓度增高、促使AMPA受体trafficking、增强突触可塑性而起作用。为证此假设，本项目使用包括先进的双光子显微镜活体阴影膜片钳、双光子解笼锁标测受体及解笼锁诱发LTP等技术，动态观察氯胺酮、GLYX-13和2R,6R-HNK对慢性不可预知应激（CUS）模型小鼠抑郁状态、CUS小鼠情感区神经元树突和树突棘形态、钙信号、AMPA受体trafficking和突触可塑性的影响；观察NMDA受体阻滞剂AP5、电压门控钙通道阻滞剂Nifedipine和胞库钙释放阻滞剂CPA是否消除上述制剂对上述指标的改善作用，阐明不同快速型抗抑郁症制剂快速启动治疗抑郁症途径，为抑郁症的防治提供依据。

抑郁症发病率、复发率和自杀死亡率高。单胺类药物起效慢，疗效低。氯胺酮快速高效治疗抑郁症已成为全球研究热点。相关研究表明抑郁症发病与突触可塑性障碍及中间神经元有关，但氯胺酮如何快速改善抑郁症突触可塑性的启动机制不清楚，给氯胺酮抗抑郁机制研究带来困扰，本项目对此进行研究。采用21天皮质酮给药诱发小鼠抑郁模型，氯胺酮（10mg/kg）改善小鼠抑郁行为。氯胺酮改善抑郁小鼠前额叶感觉等大脑皮层及海马等部位树突复杂程度及树突棘密度。光纤光度显示氯胺酮逆转抑郁模型小鼠挣扎、后肢悬起和探索时前额叶皮层神经元钙瞬变振幅的降低。双光子显微镜动态成像显示氯胺酮给药90分钟即逆转小鼠抑郁造模后期前额叶及感觉皮层锥体及PV神经元钙信号频率、幅值及局部钙信号功能连接的降低，1天达高峰并持续3-5天。胚胎电转转染小鼠感觉皮层锥体神经元AMPA受体后，双光子动态成像发现氯胺酮给药3小时即逆转小鼠抑郁造模中后期出现AMPA受体Trafficking及树突棘面积的减小，1天到高峰并持续3-5天。小鼠抑郁造模后腹腔分别注射电压门控钙通道阻滞剂Verapamil、NMDA受体拮抗剂CPP及胞库钙释放拮抗剂CPA，30分钟后氯胺酮给药，结果显示CPP及CPA阻断了氯胺酮对抑郁小鼠抑郁行为的改善、对锥体神经元钙信号频率和幅值及局部钙信号功能连接、AMPA受体Trafficking以及神经元树突复杂程度及树突棘密度的增强作用，而Verapamil对氯胺酮作用无明显影响。本项目显示氯胺酮快速改善小鼠抑郁样行为与其快速增强抑郁小鼠前额叶及感觉皮层锥体神经元兴奋性及改善突触可塑性有关，其快速启动钙内流诱发长时程增强与NMDA受体开放后钙内流及胞库钙释放有关，与电压门控钙通道钙内流及PV中间神经元作用无关，提示氯胺酮可能通过体内间接机制激活NMDA受体启动长时程增强而起到快速抗抑郁作用，同时胞库钙的释放可能也起到一定作用。