茜草素对APP/PS1双转基因小鼠肠道菌群的干预作用及机制研究

Intervention effect and mechanism of Alizarin on intestinal flora of APP/PS1 double transgenic mice

为研究茜草素(AZ)对APP/PS1双转基因小鼠(APP/PS1小鼠)肠道菌群、学习与记忆能力的影响,本实验将APP/PS1小鼠分为模型组(APP/PS1组)、AZ组[低剂量(Low)、中等剂量(Middle)、高剂量(High)]、阳性对照组[盐酸多奈哌齐(Donepezil组)],以APP/PS1阴性小鼠为空白对照组(Control组)。AZ组小鼠连续给药AZ 4周后,利用Morris水迷宫检测各组小鼠的学习与记忆能力;利用16S rRNA基因测序检测各组小鼠粪便肠样品中道菌群的变化。结果显示,与Control组小鼠相比,APP/PS1组小鼠逃避潜伏期显著延长(P<0.05)、穿越平台次数和象限停留时间极显著或显著减少(P<0.01、P<0.05),本实验选择AZ中剂量组(20 mg/kg AZ)进行后续试验;模型组小鼠肠道菌群多样性明显改变、菌落组成差异明显。给予AZ干预后,小鼠逃避潜伏期显著缩短(P<0.05)、穿越平台次数和象限停留时间均显著增加(P<0.05);AZ能有效提高APP/PS1小鼠肠道菌群多样性及改变肠道微生物结构,在门水平上,AZ能提高小鼠肠道厚壁菌门丰度,降低拟杆菌门相对丰度;在科水平上,AZ增加了小鼠肠道Muribaculaceae和Lachnospiraceae细菌的相对丰度,降低了Prevotellaceae、norank_o__Clostridia_UCG-014、Ruminococcaceae等菌群丰度;在属水平上,AZ明显提高了小鼠肠道Lactobacillus的相对丰度,进一步筛选出AZ组小鼠肠道优势菌种为o__Lactobacillales、f__Lactobacillaceae、g__Lactobacillus。通过PICRUSt2功能预测分析发现,AZ调节小鼠肠道菌群功能与炎症相关信号通路有关。本研究首次证实AZ可通过调节肠道菌群改善APP/PS1小鼠的学习及记忆能力,其机制与炎症信号通路有关,为AZ的临床应用奠定基础。

To investigate the effects of Alizarin(Alizarin,AZ)on intestinal flora and learning and memory ability of APP/PS1 double transgenic mice(APP/PS1 mice),the APP/PS1 mice were divided into model group(APP/PS1 group),alizarin groups(AZ Low,Middle,and High group)and positive control group(Donepezil group),and the APP/PS1 negative mice were used as blank control(Control group).After 4 weeks of continuous administration of AZ,the learning and memory abilities of mice in each group were evaluated by Morris water maze,and the changes of intestinal flora in feces of mice were detected by 16S rRNA gene sequencing.The results showed that compared with the control group,the escape latency of mice in APP/PS1 group prolonged significantly(P<0.05),the number of platform crossing and the quadrant residence time decreased significantly(P<0.01,P<0.05),and the diversity of intestinal flora and the colony composition changed significantly.After intervention with AZ,the escape latency of mice shortened significantly(P<0.05),the number of platform crossing and the quadrant residence time increased significantly(P<0.05),AZ could effectively increase the diversity of intestinal flora and change the composition of microorganisms in APP/PS1 mice.For AZ group,the abundance of Bacteroides increased and the relative abundance of Bacteroides decreased at the phylum level;the relative abundance of Muribaculaceae and Lachnospiraceae bacteria increased and the abundance of Prevotellaceae,norank_o__Clostridia_UCG-014,Ruminococcaceae and other bacteria decreased at the family level;the relative abundance of Lactobacillus significantly increased at the genus level,and the dominant bacteria in AZ group were screened as o__Lactobacillales,f__Lactobacillaceae and g__Lactobacillus.Further function prediction analysis through PICRUSt2 found that the function of AZ regulating flora was related to inflammation-related signal pathway.This study revealed for the first time that AZ can improve the learning and memory ability of APP/PS1 mice by regulating intestinal flora,and its mechanism is related to inflammatory signal pathway,laying a foundation for the clinical application of AZ.