抑郁模型大鼠脑室-嗅觉神经发生系统神经发生降低的机制及其与抑郁样行为关系的研究

Major depressive disorder (MDD) is one of the most prevalent forms of mental illness, but the specific pathology is still unknow. In recent years, the relationship between MDD and the largest neurogenesis brain region in adult mammalian: ventriculo-olfactory neurogenic system (VONS) attracts the most attention of worldwide scholars. Not only the olfactory bulb volume and olfactory sensitivity of depressive patients' were reduced, but also appeared in animal model of depression. The consistency of basic and clinical research might be another brand-new finding second to the hippocampal neurogenesis dysfunction in depression animal models, which is a breakthrough to explore the pathogenesis of depression. Based on the previous finding of reduced neurogenesis of VONS in rat model of depression, we propose to utilize methods of animal behavior, molecular and modern cell biological techniques: 1. To explore the relationship between the VONS neurogenesis dysfunction in rat model of depression and depressive-like behaviors; 2. To probe into the protein level changes in key brain region of VONS neurogenesis - subventricular zone and critical proteins' effects on neural stem cells proliferation and differentiation. We aim at interpreting the molecular mechanisms of reduced VONS neurogenesis in the rat model of depression and the relationship between depressive-like behaviors, helping to elucidate the pathogenesis of depression.

抑郁症是严重危及人类健康的最常见的精神疾病，发病机制尚未明了。近年来，成年哺乳动物最大的神经发生脑区- - 脑室-嗅觉神经发生系统（VONS，包括侧脑室下区、吻侧流束、嗅球）与抑郁症的关系受到许多学者的关注。不仅抑郁症患者有嗅球体积缩小和嗅觉敏感性降低，而且在抑郁模式动物亦发现VONS神经发生减少、嗅球体积减小和嗅觉功能障碍。这一基础与临床研究的一致性，可能是继抑郁模式动物海马神经发生障碍后又一新的发现，有望成为探索抑郁症发病机制新的突破点。我们在前期发现抑郁模型大鼠VONS神经发生降低的基础上，拟运用动物行为学和细胞分子生物学等技术，探讨抑郁模型大鼠VONS神经发生降低与抑郁样行为的关系，并探究VONS神经发生关键脑区- - 侧脑室下区蛋白水平改变及关键蛋白对神经干细胞增殖分化的影响，旨在阐释抑郁模型大鼠VONS神经发生降低的分子机制及其与抑郁样行为的关系，进而有助于阐明抑郁症的发病机制。

我们前期发现抑郁模型大鼠脑室-嗅觉神经发生系统神经发生降低，但机制不清。在本项目的资助下，1.本课题组运用神经发生基因芯片研究发现CREB、BDNF在抑郁模型大鼠侧脑室下区表达显著下调；应用RT-PCR和Western Blotting进一步验证了正常大鼠与抑郁大鼠侧脑室下区CREB和BDNF蛋白的表达，结果与基因芯片结果一致，提示Camp-CREB-BDNF信号通路可能参与调控了抑郁模型大鼠侧脑室下区神经发生。2.本课题组围绕嗅觉传导通路上与脑室-嗅觉神经发生系统相联系的上游组织嗅黏膜研究发现，抑郁模型大鼠嗅黏膜萎缩、正常嗅上皮细胞的有序排列特征消失，并分别采用p75NGFR标记基底细胞，GAP43标记未成熟嗅细胞和OMP标记成熟嗅细胞发现这些细胞均不同程度减少，提示嗅黏膜萎缩也可能是抑郁症患者嗅觉功能障碍的原因之一。3. 鉴于嗅黏膜可通过鼻内窥镜引导下活体、动态取材，具有创伤小、简便、快捷、病人易于接受等优点，从嗅黏膜探究抑郁症发病机制成为可能，故本课题组采集成人嗅黏膜组织，用组织块培养法培养成人嗅细胞，神经球培养法纯化干细胞，促神经分化培养基诱导干细胞向神经细胞分化，检测氟西汀对嗅黏膜神经干细胞增殖及分化的影响。结果显示体外培养嗅黏膜神经干细胞呈球状聚集；Nestin、MAP2、TUJ1免疫荧光阳性；氟西汀促进嗅黏膜神经干细胞增殖并向神经细胞转化。提示有望通过嗅黏膜神经干细胞探究抑郁症的发病机制。4.采用课题组前期建立的代谢组学方法，分别对抑郁大鼠前额叶、外周血PBMC及嗅球进行了代谢组学研究，发现差异代谢物质主要为神经递质代谢物、能量代谢物和氧化应激代谢物等。本研究结果提示神经递质代谢紊乱、能量代谢紊乱和氧化应激代谢紊乱可能与抑郁症的发病机制有关。外周血PBMC代谢物检测有望成为诊断抑郁症的客观生物标志物。