α7nAchR通过BDNF/TrkB通路调控NR2B表达在子痫抽搐中的作用及机制研究

Eclampsia is an epileptic convulsion based on preeclampsia, its pathogenesis is unclear. We found that the excessive inflammation in preeclampsia reduced the threshold of eclampsia-like seizure, and activation of α7nAchR could reduce neuroinflammation, alleviate the degree of neuronal damage, and slow down the onset of eclampsia. α7nAchR was also expressed on the neuron, whether it could act on neurons after activation to play a protective role, and what was the mechanism? Our study demonstrated that the NR2B subunit of NMDAR mediated excitotoxic death of neurons. Preliminary experiments showed that the expression ofα7nAchR on neurons in eclampsia was down-regulated, while the expression of NR2B was up-regulated. The NR2B expression could be down-regulated by activation of α7nAchR; we further found that activation of α7nAchR inhibited the activity of the BDNF/TrkB pathway which was upstream of NR2B. Accordingly, we hypothesized that activation of α7nAchR could reduce the excitability of neurons and slow down the onset of eclampsia, the mechanisms were by inhibiting the expression of BDNF/TrkB pathway and NR2B. This project aimed to elucidate the mechanism of α7nAchR regulating eclampsia-like seizure through pharmacology and gene manipulation technology related to adenovirus in animal models of eclampsia and in vitro convulsion models, and provide scientific basis for the development of new drugs for treating eclampsia.

子痫是子痫前期基础上的痫性抽搐，其发病机制不清。我们发现：子痫前期的炎性状态降低了子痫抽搐的阈值，激活α7nAchR可降低神经炎性，减轻神经元受损程度，减缓子痫抽搐发作；α7nAchR亦在神经元上表达，其激活后是否可作用于神经元发挥保护作用？机制是什么？我们研究表明NMDAR的NR2B亚基介导神经元兴奋性毒性死亡。预实验显示子痫抽搐中神经元上α7nAchR 表达下调，NR2B表达上调；激活 α7nAchR可下调NR2B；进一步发现激活α7nAchR可抑制NR2B上游的BDNF/TrkB通路活性。据此我们设想α7nAchR激活后，可降低神经元的兴奋性，减缓子痫抽搐的发作，此作用可通过抑制BDNF/TrkB通路和NR2B表达来实现。本项目拟通过类子痫动物模型和体外抽搐模型，采用药理学和腺相关病毒介导的基因操作手段，阐明α7nAchR调控子痫抽搐发作的机制，为开发新的治疗子痫药物提供科学依据。

子痫/重度子痫前期是妊娠期严重并发症，其发病机制尚未完全阐明。我们从神经科学角度研究发现，子痫抽搐发作时，皮质区神经元相对于海马区更易受损；子痫前期动物皮质区神经元中的α7nAchR表达相对于正常组显著下降，在类子痫组其表达量进一步下调，提示α7nAchR表达量下调参与了子痫的发生发展。在类子痫动物模型中，药理学手段激活α7nAchR，可上调PI3K-AKT信号通路，减轻皮质区神经元凋亡；α7nAchR拮抗剂和PI3K拮抗剂均可抑制上述反应，提示α7nAchR通过上调皮质区神经元中的PI3K-AKT通路，减轻神经元受损程度，减缓子痫抽搐发作。子痫是在子痫前期基础上发生的抽搐，是子痫前期的严重阶段。前期结果显示子痫前期的全身过度炎性反应降低了子痫抽搐的阈值，而此反应与母胎界面的异常炎症密切相关。我们进一步发现子痫前期患者蜕膜巨噬细胞中α7nAchR表达相对于正常妊娠组下调，伴随着炎症型的巨噬细胞M1极化增加。在子痫前期动物模型中，应用α7nAchR激动剂可上调α7nAchR活性，抑制巨噬细胞M1极化和巨噬细胞中炎性因子的分泌，上调滋养细胞侵袭力标志物MMP-9，改善胎盘螺旋动脉重塑情况；此作用被α7nAchR拮抗剂逆转。为把 α7nAChR活性调节作为子痫/子痫前期防治的新靶点提供理论依据，此将有助于降低围产期子痫发病率，对于减少孕产妇和胎儿的死亡率具有重要社会意义。