SIRT1调节抑郁症脑内自噬和炎症反应影响5-羟色胺能神经突触可塑性的机制研究

Major depression is a common mental disease that psychosocial stress has been postulated to play a vital role in. There is accumulating evidence showed that chronic unpredictable mild stress (CUMS) activates microglia in the brain, it is well known that disturbances in microglia function has an etiological role in mood disorder also, long-term adverse stress can cause emotional, cognitive and physical barriers and the inflammation reaction can lead to brain damage. Regulating microglia activation is essential to alleviate nerve inflammation. SIRT1 expression was reduced in peripheral white blood cells of patients with mood disorders, but the mechanism remains unclear. Our preliminary results showed microglia activation and the expression changes of SIRT1 and LC3 in corticosterone induced cell depression model and CUMS rat depression model. Based on the results above, we hypothesize that SIRT1 regulates serotoninergic neural circuits by affecting TLR4/NLRP3 signaling pathway, which modulates autophagy and inflammation in microglia and further influences synaptic plasticity of serotonin neurons. By using multiple discipline approaches including genetic modification, electrophysiology and immunofluorescence, as well as genetic engineering mouse, AAV-mediated molecular genetics and in vivo pharmacological tools, the present proposal is expected to provide novel insights for the understanding of the TLR4 / NLRP3 signal pathway and autophagy alteration following SIRT1 modulation both in vitro and in vivo depression model, and will illuminate synaptic plasticity of serotonin neurons which is mediated by depression inflammation. This provides a new train of thought and theory basis.

抑郁症是一种常见的精神心理疾病。慢性社会心理应激会引起情感和认知等障碍、诱发脑的炎症性损伤，是抑郁症重要诱因。调控小胶质细胞活化是减轻神经炎症反应的关键环节。研究发现抑郁症患者外周血白细胞的SIRT1水平降低，机制不明。我们前期研究揭示在皮质酮诱导的细胞和大鼠抑郁模型中，均提示小胶质细胞被激活，SIRT1和自噬相关蛋白LC3表达减少。基于以上结果我们提出假设：在小胶质细胞中SIRT1可通过调控TLR4/NLRP3信号通路、影响自噬以及炎症反应，进而改变5-羟色胺能神经元的突触可塑性。本项目拟结合基因表达调控、免疫荧光和电生理等技术，建立在体与离体抑郁症模型，利用SIRT1腺相关病毒和基于Cre-loxp策略的转基因小鼠探讨SIRT1对小胶质细胞TLR4/NLRP3信号通路和自噬的调控机制，阐明抑郁症脑内炎症反应对5-羟色胺能神经突触可塑性影响的机制，为抑郁症的治疗新的切入点。

抑郁症是一种常见的精神心理疾病，慢性心理应激会引起情感障碍，是抑郁症重要诱因。抑郁症患者外周血白细胞内SIRT1水平降低，但机制尚不清楚。本研究选用VSC4.1脊髓前角运动神经元构建了细胞应激模型，利用脂多糖注射和慢性不可预测温和应激（CUMS）构建了小鼠抑郁症模型，研究了SIRT1调控神经炎症和自噬的相关机制。利用荧光定量PCR和Western Blot检测细胞和小鼠模型中炎症和自噬相关分子表达变化。采用TUNEL、SIRT1和Iba1等免疫荧光染色分析SIRT1在细胞和小鼠海马内表达变化，以及对神经元和小胶质细胞的影响。利用腺相关病毒脑内注射、SIRT1激动剂干预Pv-cre、Pet1-cre和Sirt1-FloxP等转基因小鼠，采用旷场实验、蔗糖水偏好测试和强迫游泳实验评估小鼠抑郁样行为，着重探讨了海马SIRT1对抑郁症炎症和自噬的影响，以及PV神经元在抑郁症模型中的作用。发现皮质酮诱导的VSC细胞应激模型中SIRT1表达下降、LC3-II/I和ATG5等自噬因子表达被激活，过表达或敲减细胞应激模型中的SIRT1能促进或抑制细胞自噬等过程。LPS和CUMS诱导小鼠出现抑郁样行为，腹侧海马 SIRT1表达下降，腹侧海马脑区齿状回PV中间神经元数目显著减少、小胶质细胞被激活、炎症小体活化、自噬水平降低。利用腺相关病毒敲除腹海马齿状回PV神经元后诱导了抑郁样行为，增强 SIRT1活性（激动剂干预）能改善抑郁样行为。本研究提出了抑郁症治疗的新策略：增加脑内SIRT1表达、抑制神经炎症及靶向调控GABA能神经元。小鼠抑郁样行为与海马内SIRT1水平降低有关，涉及SIRT1和PV神经元对自噬和BDNF调控机制；白藜芦醇通过刺激SIRT1和诱导自噬抑制来缓解小鼠抑郁样行为；本研究提供了靶向SIRT1改善小鼠抑郁症的新策略，为寻找抑郁症新药物靶点提供参考。