BDNF-TrkB信号通路在新型毒品K粉依赖中的作用及机制研究

Ketamine abuse has been increasing rapidly, but the mechanism of ketamine dependence remains elusive. Numerous studies have shown that dopamine rewarding system had played a vital role in the formation of drug dependence. In our previous study, we have found that high dopaminergic status induced by chronic ketamine treatment was related to up-regulated BDNF expression in a ketamine abuse animal model. Together with literature, we hypothesize that ketamine activates dopamine rewarding system via BDNF-TrkB signaling pathway during the formation of dependence. To test the hypothesis, a ketamine abuse model will be established in ICR mice to examine the role of BDNF-TrkB signaling pathway in the process of ketamine dependence and withdrawal. Firstly, effects of ketamine on BDNF-TrkB signaling pathway will be examined by immunohistochemistry and Western Blot. Secondly, blocking agent or BDNF will be delivered to specific brain regions through stereotactic surgery to inhibit or activate the pathway, and then the animal behavioral studies will be performed to examine their effects on psychological dependence and withdrawal symptoms and to clarify the brain regions which invovled in ketamine dependence. The present study will not only elucidate the mechaninsm of ketamine dependence, but also prvovide new target to beat the newly abuse drug.

氯胺酮滥用流行加剧，但其依赖形成的分子机制不明。既往的研究显示，多巴胺奖赏系统的激活可能在其中发挥了重要作用。我们前期在氯胺酮滥用小鼠模型中发现，氯胺酮诱导的中脑高多巴胺能状态与BDNF表达上调有关。结合文献，我们推测：氯胺酮可能通过BDNF-TrkB信号通路来激活多巴胺奖赏系统，导致对其产生精神依赖。为了进一步证明该假说，本研究首先将构建慢性氯胺酮滥用小鼠模型，应用动物行为学方法研究氯胺酮的成瘾规律，采用免疫组化和分子生物学方法观察氯胺酮对BDNF-TrkB信号通路的上调作用，初步阐明该信号通路在氯胺酮依赖中的作用；然后，通过立体定位注射技术证实BDNF-TrkB信号通路在氯胺酮依赖中的作用并探讨其分子机制，明确该信号通路在氯胺酮依赖中发挥作用的脑区。本研究不仅有助于阐明氯胺酮依赖形成的分子机制，而且有望为该类新型毒品成瘾治疗提供新靶点。

作为一种精神活性物质，氯胺酮可能对中枢神经系统产生深远的影响。在前期相关工作的基础上，本课题以慢性腹腔注射建立了氯胺酮成瘾小鼠模型，探讨BDNF及其相关信号通路在氯胺酮滥用成瘾中的神经生物学机制。动物行为学分析发现，慢性氯胺酮暴露可导致小鼠条件性位置依赖，氯胺酮停药后，小鼠在高价十字迷宫开放臂的活动显著减少，出现明显的焦虑样行为；生化分析和分子生物学结果表明氯胺酮注射能同时上调神经营养因子BDNF和多巴胺合成限速酶TH的表达，增加多巴胺的浓度。AMPA受体阻断剂NBQX可以通过抑制氯胺酮对多巴胺奖赏通路的激活，减轻成瘾行为和戒断症状。此外，我们还采用PCR芯片技术对神经递质及其相关基因进行了筛选，发现氯胺酮暴露能改变多个与物质依赖与成瘾相关的基因表达。上述结果有助于进一步明确BDNF及其相关信号通路在氯胺酮成瘾中的作用机制以及探讨以BDNF及相关信号通路为靶点的氯胺酮成瘾防治提供了实验依据。