高胆固醇饮食诱导小鼠抑郁模型的神经-肠道相互作用研究

Study on the neuro-intestinal interaction in a high cholesterol diet induced depression model in mice

目的基于肠道菌群紊乱探讨小鼠抑郁样行为的“肠-脑”机制。方法选取18只无特定病原体的雄性C57BL/6J小鼠,随机分成三组(n=6):对照组、高胆固醇饮食(HCD)组和慢性束缚应激(CRS)组。通过HCD诱导小鼠抑郁样行为。采用酶联免疫试剂盒检测血清5-羟色胺(5-HT)、脑源性神经营养因子(BDNF)、神经生长因子(NGF)、白细胞介素-1β(IL-1β)和肿瘤坏死因子-α(TNF-α)的水平。通过PCR进行粪便微生物群分析。结果与对照组比较,HCD组、CRS组血清和脑组织中NGF、BDNF、5-HT水平均降低(P<0.05),血清LPS水平增加(P<0.05),脑组织中TNF-α、IL-1β水平升高(P<0.05)。基于PCOA分析和Unifrac聚类分析(Adonis检验),三组之间的微生物组成存在差异(P<0.05)。与对照组比较,HCD组、CRS组普雷沃氏菌属、拟普雷沃氏菌属、巴恩斯氏菌属和另枝菌属的丰度降低,类杆菌属和阿克尔曼菌属的丰度增加(P<0.05)。拟普雷沃氏菌属、普雷沃氏菌属、另枝菌属、臭杆菌属和粘螺旋菌属的丰度与血清BDNF水平呈正相关(P<0.05),而梭菌属XⅧ、经黏液真杆菌属、粪厌氧棒杆菌属和阿克曼菌属的丰度与血清BDNF水平呈负相关(P<0.05)。普雷沃氏菌属和巴恩斯氏菌属的丰度与血清5-HT水平呈正相关(P<0.01),经黏液真杆菌属的丰度与血清5-HT水平呈负相关(P<0.01)。普雷沃氏菌的丰度与IL-1β水平呈负相关(P<0.05)。另枝菌属的丰度与TNF-α、IL-1β水平呈负相关(P<0.05)。结论HCD诱导的神经炎症通过肠道微生物促进了小鼠的抑郁样行为。

Objective To explore the gut-brain mechanism of depressive behavior in mice based on intestinal flora disorder.Methods A total of 18 male C57BL/6J mice without specific pathogens were randomly divided into three groups(n=6):control group,high cholesterol diet(HCD)group and chronic restraint stress(CRS)group.Depression-like behaviors were induced in mice through HCD.Serum levels of 5-hydroxytryptamine(5-HT),brain-derived neurotrophic factor(BDNF),nerve growth factor(NGF),interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)were detected by enzyme-linked immunosorbent assay.The fecal microflora was analyzed by PCR.Results Compared with control group,the levels of NGF,BDNF and 5-HT in serum and brain tissue in HCD group and CRS group decreased(P<0.05),while the levels of LPS in serum and TNF-αand IL-1βin brain tissue increased(P<0.05).Based on PCOA analysis and Unifrac cluster analysis(Adonis test),there were differences in microbial composition among three groups(P<0.05).Compared with control group,the abundances of Prevost,Bacteroides Prevost,Barnabas and Cladosporium decreased,and the abundances of Bacteroides and Achermann increased in HCD and CRS groups(P<0.05).Abundances of Bacteroides Prevost,Prevost,Cladosporium,Odoribacter and Myxospira were positively correlated with serum BDNF level(P<0.05),while those of Clostridium XⅧ,Eubacterium transmyxus,Corynebacterium faecalis and Ackermann were negatively correlated with serum BDNF level(P<0.05).Abundances of Prevost and Barnabas were positively correlated with serum 5-HT level(P<0.01),and that of Eubacterium transmyxus was negatively correlated with serum 5-HT level(P<0.01).There was a negative correlation between the abundance of Prevost and the level of IL-1β(P<0.05),and negative correlations among the abundance of Cladosporium and levels of TNF-αand IL-1β(P<0.05).Conclusion Neuroinflammation induced by HCD promotes depression-like behaviors in mice through the gut microbe.