龙眼肉调节肠道菌群和BDNF-TrkB通路抗AD的作用机制研究

Study on Anti-AD Mechanism of Longan Aril by Regulating Intestinal Flora and BDNF-TrkB Signaling Pathway

目的:基于肠道菌群和脑源性神经营养因子(BDNF)-酪氨酸激酶受体B (TrkB)信号通路探讨龙眼肉抗阿尔茨海默病(AD)的作用机制。方法:采用煎煮法制备龙眼肉水提取物,采用D-半乳糖(140 mg·kg–1,ip)/AlCl3(20 mg·kg–1,ig)联合诱导建立小鼠AD模型,Morris水迷宫检测小鼠学习记忆能力,16S-rDNA测序检测小鼠粪便菌群多样性,Western blot检测小鼠海马区淀粉样前体蛋白(APP)、磷酸化Tau蛋白(p-Tau)、BDNF、TrkB和p-TrkB表达。结果:龙眼肉缩短了AD小鼠的逃避潜伏期(P<0.01);增加了其平台穿越次数、停留时间和停留时间百分比(P<0.001);降低了AD小鼠海马APP、p-Tau蛋白水平(P<0.05);改变了AD小鼠粪便微生物在界、门、纲、目、科、属、种7个层面上的多样性差异,以属水平为例,使异常升高的拟普雷沃菌属、瘤胃球菌科_UCG-014属、普雷沃氏菌科_UCG-001属、理研菌科RC9_gut_group属、瘤胃梭菌属和瘤胃球菌属_1丰度显著降低(P<0.05),鼠杆菌属和毛螺菌科_UCG-001属丰度显著升高(P<0.01);并且提高了BDNF、p-TrkB及p-TrkB/TrkB相对表达(P<0.05)。结论:龙眼肉可以改善AD小鼠的学习记忆能力,调节菌群多样性、激活BDNF-TrkB信号通路可能是其抗AD的作用机制。

Objective:Based on intestinal flora and brain-derived neurotrophic factor(BDNF)-tropomyosin receptor kinase B(TrkB)signaling pathway,the anti-Alzheimer's disease(AD)mechanism of Longan Aril(LA)was explored.Methods:The decoction of LA was prepared by the decocting method.The AD model of mice was induced by intraperitoneal injection of D-galactose(140 mg·kg–1)and intragastric administration of AlCl3(20 mg·kg–1).Morris water maze test was used to detect the learning and memory ability of rats,and 16S-rDNA sequencing was used to detect the diversity of fecal flora in mice.Western blot assay was used to detect the expressions of amyloid precursor protein(APP),phosphorylated Tau protein(p-Tau),BDNF,TrkB,and phosphorylated TrkB(p-TrkB)in the hippocampus of mice.Results:After being treated with LA,the escape latency of AD mice was reduced(P<0.01),and their crossing times,staying time,and percentage of staying time in the platform were increased(P<0.001);the levels of APP and p-Tau protein in the hippocampus of AD mice were decreased(P<0.05),and the intestinal flora diversity in the feces of AD mice was changed at seven levels:kingdom,phyla,class,order,family,genus,and species.With the genus level as an example,the abundance of abnormally increased Alloprevotella,Ruminococcaceae_UCG-014,Prevotellaceae_UCG-001,Rikenellaceae_RC9_gut_group,Ruminiclostridium,and Ruminococcus_1 in AD group was significantly reduced(P<0.05),and the abundance of Muribaculum and Lachnospiraceae_UCG-001 was significantly increased(P<0.01).In addition,the relative expressions of BDNF,p-TrkB,and p-TrkB/TrkB were significantly increased(P<0.05).Conclusion:LA can improve the learning and memory abilities of AD mice,and its anti-AD mechanism is related to regulating intestinal flora diversity and activating the BDNF-TrkB signaling pathway.