基于肠-肝-脑轴的色氨酸代谢平衡研究疏肝理脾方药治疗抑郁症的作用机制和药效物质

Tryptophan is mainly metabolized in gut, liver and brain. According to the 5-HT-KYN hypothesis, more tryptophan metabolism in gut and liver leads to less serotonin yield in brain, which is etiology of depression. Some classical Shugan Lipi formulas are used to treat depression in clinic, such as Xiaoyao San, Sini San, and Chuaihu Shugan San. Considering the channel tropism of ingredient herbs in these formulas is liver and gut but the therapeutic organ is brain, we assume that Shugan Lipi formulas treat depression by reducing tryptophan metabolism in gut and liver and promote serotonin yield in brain, and that the antidepressant effect of these formulas may be up to the sex of patients. Since the composing rules of these formulas are similar we also assume that they have some pharmacodynamic substances in common. Therefore, we are going to treat depression mice model with Shugan Lipi formulas, observe the distribution of tryptophan metabolites in gut, liver and brain, assay activity of the key enzymes during tryptophan metabolism and examine their genetic and proteinic expression levels, so that we’ll discover the association of mechanism of Shugan Lipi formulas for depression therapy with tryptophan metabolism balance and the differences of their therapeutic effect between males and females. We’ll also assay these items as indexes to find these formulas’s common pharmacodynamic substances by using the method of differential efficacy of serum chromatographic analysis. Our research will break through from tryptophan metabolism of gut-liver-brain axis, which is different from conventional antidepressant research. This project all demonstrates the theory of channel tropism systematology and holism in Chinese traditional medicine. It also has great significance to modernization of Chinese traditional medicine and helps to explore new antidepressant.

色氨酸代谢主要发生在肠、肝、脑中，5-HT-KYN学说认为，色氨酸在肝、肠中代谢增多导致脑中5-羟色胺生成不足是抑郁症的病因。中医用逍遥散、四逆散、柴胡疏肝散等疏肝理脾方药治疗抑郁症，因用药归经肝、脾而疗效在脑，我们提出假说：疏肝理脾方药通过抑制肝、肠中色氨酸代谢、促进脑中5-羟色胺生成起到抗抑郁作用；因女子以肝为先天，疏肝理脾方药治疗抑郁症可能有性别选择性；疏肝理脾各方药组方相近，应具有共性药效物质基础。为此，我们将疏肝理脾方药给予抑郁症小鼠后，通过考察色氨酸代谢产物在肝、肠、脑中的分布及代谢关键酶的活性和表达水平，揭示疏肝理脾方药治疗抑郁症与色氨酸代谢的关系及其性别差异性，并以这些测定指标为导示，利用药效差示血清色谱法找出共性的药效物质基础。本项目以肠-肝-脑轴色氨酸代谢平衡为切入点，突破常规抗抑郁研究思路，充分展示中医归经理论和整体观，对中医现代化和发现新型抗抑郁药具有重要意义。

色氨酸（TRP）是人体必需氨基酸，由食物获取的色氨酸用于蛋白质合成后，剩余的在体内分解代谢。95%的色氨酸代谢发生在肝，由TDO代谢生成犬尿氨酸（KYN），1~5%色氨酸代谢发生在脑或肠中，生成5-HT。5-HT是一种兴奋性神经递质，与抑郁症的发生密切相关，外周的5-HT因血脑屏障不能进入中枢系统。越来越多的证据显示犬尿氨酸及其下游代谢产物也参与了抑郁症的病理过程。本项目结合肝主疏泄理论，提出假说：以逍遥散、四逆散、柴胡疏肝散为代表的疏肝理脾方药归经于中医“肝”、“脾”，通过抑制肝和肠中的外周色氨酸代谢路径，促进脑中色氨酸生成5-HT，使肠-肝-脑轴的色氨酸代谢恢复平衡，从而起到抗抑郁的作用。为此，本项目研究了抑郁刺激下小鼠肝、肠、脑等部位色氨酸代谢情况，给予疏肝理脾方药后对色氨酸代谢平衡的影响；以UPLC-Q-TOF-MS全成分指纹图谱技术分析柴胡疏肝散、四逆散、逍遥散共同含有的化学成分及入血成分，通过灰度关联分析，找出共性物质基础，再经体内外实验验证。研究发现，三联一复合应激使小鼠肝脏TDO表达及酶活性显著升高，导致KYN/TRP比值明显增大，体内色氨酸代谢失调，并且雄性鼠比雌性鼠受应激影响更大。给予疏肝理脾三方后均有不同程度的逆转作用，以柴胡疏肝散效果最为明显。谱效结合分析，找出共性物质基础主要来自白芍的芍药苷类成分和陈皮、枳实、枳壳中橙皮苷等黄酮成分。经过整体动物实验和含药血清的细胞实验，确认白芍是调节色氨酸代谢的关键显效药味。本项目以肠-肝-脑轴色氨酸代谢平衡为切入点，突破常规抗抑郁研究思路，充分展示中医归经理论和整体观，对中医现代化和发现新型抗抑郁药具有重要意义。