The Essential Role of Presynaptic NMDA Receptors in The Fast Antidepressant Actions of Ketamine and Its Metabolite

项目总结/摘要 临床试验和动物实验的证据表明，单次亚麻醉剂量的 克他命产生快速的抗抑郁反应。然而，拟精神病的特性 和滥用氯胺酮的可能性，在促进这种化合物被用作 抑郁症的一般治疗。关于速效机制的报告 克他命的抗抑郁作用是有争议的特别是，它仍然不确定， 分子事件介导氯胺酮或其代谢物增强兴奋性突触的作用 传输在初步实验中，观察到氯胺酮及其代谢物， cis-6-HNK，有效增强的Shaffer侧支-CA 1（SC-CA 1）EPSC和fEPSP。这些 MK-801可模拟并完全阻断这种作用，但GABA不能消除这种作用 受体阻断氯胺酮有效地增加总的和表面GluA 1表达， GluA 1 Ser 845位点的磷酸化。此外，氯胺酮未能增强SC-CA 1 fEPSP 并诱导GluA 1 S845 A基因敲入小鼠产生抗抑郁样反应。此外，委员会认为， CA 3神经元上的NMDA受体缺失，但CA 1细胞上的NMDA受体未被完全消除 氯胺酮诱导的SC-CA 1突触传递增强。拟建工程 设计实验来测试GluA 1 Ser 845磷酸化和突触前神经元的作用。 氯胺酮和HNK中的NMDA受体产生速效抗抑郁反应， 以及它们的细胞和分子基础电生理技术将被结合， 包括采用细胞生物学技术如蛋白质印迹的全细胞膜片钳， 表面蛋白的生物素化和GluR 1 S845 A敲入小鼠，CA 1细胞或CA 3细胞特异性 NR 1基因敲除小鼠、HCN 1基因敲除小鼠以及行为测量，以实现 设计实验。拟议的项目将扩大知识，了解 氯胺酮快速抗抑郁作用的细胞机制。更好地理解 氯胺酮的速效抗抑郁作用将促进新一代药物的设计， 速效抗抑郁药，为抑郁症提供更好的治疗。

Project Summary/Abstract Evidence from clinical trials and animal experiments shows a single subanesthesia dose of ketamine produces rapid antidepressant responses. However, the psychotomimetic properties and abuse potential of ketamine necessitate caution in promoting this compound to be used as a general treatment of depression. The reports on the mechanisms underlying the rapid-acting antidepressant effects of ketamine are controversial. Particularly, it remains uncertain which molecular events mediate ketamine’s or its metabolites’ action in enhancing excitatory synaptic transmission. In preliminary experiments, it was observed that both ketamine and its metabolite, cis-6-HNK, potently enhanced Shaffer collateral-CA1 (SC-CA1) EPSCs and fEPSPs. These actions were mimicked and completely occluded by MK-801, but not eliminated by GABA receptor blockade. Ketamine potently increased total and surface GluA1 expression and the phosphorylation of GluA1 Ser845 site. In addition, ketamine failed to potentiate SC-CA1 fEPSPs and induce the antidepressant-like responses in GluA1 S845A knock-in mice. Furthermore, deletion of NMDA receptor on CA3 neurons but not on CA1 cells completely eliminated ketamine-induced potentiation on SC-CA1 synaptic transmission. In the proposed project experiments are designed to test the role of GluA1 Ser845 phosphorylation and presynaptic NMDA receptors in ketamine- and HNK-produced rapid-acting antidepressant responses as well as their celluar and molecular bases. Electrophysiological techniques will be combined, including whole-cell patch clamp with cell biological technique such as Western blotting, biotinylation of surface proteins and GluR1 S845A knock-in mice, CA1 cell- or CA3 cell-specific NR1 knockout mice, HCN1 knockout mice as well as behavioral measurements to achieve the designed experiments. The proposed project will expand knowledge in understanding the cellular mechanisms of fast-acting antidepressant actions of ketamine. A better understanding of ketamine’s fast-acting antidepressant effects will promote the design of a new generation of rapid-acting antidepressant to offer a better therapy to depression.