嗜黏蛋白阿克曼菌对鲤糖代谢的调控机制

The regulation mechanism of Akkermansia muciniphila on glucose metabolism of the Cyprinus carpio

为探究巴氏灭活的阿克曼菌(Akk)调控鲤糖代谢的分子机制,实验通过不同糖水平(20%、30%、40%、50%葡萄糖)探究体重(10.5±1.0)g的鲤4周和8周时胰高血糖素样肽-1(glucagon-like peptide-1,GLP-1)分泌及阿克曼菌定植的时空变化;在不同糖水平实验基础上,设置含有40%葡萄糖的3个不同Akk浓度(10^(8)、10^(9)和10^(10)CFU/g)P-Akk组,探究添加P-Akk 4周后对鲤(16.38±0.39 g)糖代谢及GLP-1的调控;通过P-Akk孵育鲤原代肝脏、肠细胞实验,共同探究不同糖水平下鲤肠道Akk、GLP-1对糖代谢的调控机制。结果显示,(1)随着饲料中葡萄糖含量的升高,鲤血清中GLP-1b含量显著降低,4周时高糖组鲤肠道GLP-1a、GLP-1b以及肠道内容物中Akk丰度均显著降低,但8周时无显著性差异。(2)P-Akk处理后,鲤血清中葡萄糖、GLP-1含量显著减少;中肠绒毛高度、肌层厚度显著增加,GLP-1含量减少,短链脂肪酸含量增加,muc2 mRNA表达水平升高;此外,P-Akk上调肝脏中ampk、pi3k、akt及糖酵解基因gk、pfk mRNA表达量,下调糖异生基因pepck mRNA表达量。(3)原代肝脏、肠细胞孵育结果显示,P-Akk处理肠细胞后GLP-1含量显著减少,而gpr40的mRNA表达量升高;此外肝脏细胞中糖酵解基因gk、pfk mRNA表达量显著升高。综上,外源添加P-Akk可以缓解高糖饲料引起的血糖升高,维持葡萄糖稳态。该研究结果可为Akk作为益生菌在水产饲料中的应用提供理论基础。

Currently,the majority of studies investigating the effects of Akkermansia muciniphila primarily focus on blood glucose homeostasis,adipose tissue accumulation,intestinal permeability,and body weight regulation.However,these studies are predominantly limited to human and mammalian subjects.The specific mechanism by which A.muciniphila regulates glucose metabolism in fish remains unclear.So we investigate the molecular mechanism of pasteurized A.muciniphila regulating glucose metabolism in Cyprinus carpio.In this study,different sugar concentrations(20%,30%,40%,50%glucose)were examined to investigate the temporal and spatial variations in glucagon-like peptide-1 secretion and A.muciniphila colonization at 4 and 8 weeks of C.carpio(10.5±1.0 g).Based on the different sugar concentration tests,groups with a glucose level of 40%and three varying concentrations of pasteurized A.muciniphila(10^(8),10^(9),10^(10)CFU/g)were established.The regulation of glucose metabolism and glucagon-like peptide-1 in C.carpio(16.38±0.39 g)after four weeks of pasteurized A.muciniphila supplementation was explored.Additionally,the regulatory mechanism of intestinal A.muciniphila and glucagon-like peptide-1 on carp's glucose metabolism at different glucose levels was investigated through experiments involving primary liver and intestinal cells incubated with pasteurized A.muciniphila.The results demonstrated the following findings:(1)with an increase in dietary glucose content,there was a significant decrease in serum glucagonlike peptide-1b levels(P<0.05).(2)following pasteurized A.muciniphila treatment,there was a significant reduction in serum glucose and glucagon-like peptide-1 levels(P<0.05).Moreover,there were notable increases in villus height and muscle thickness of the midintestine along with a decrease in glucagon-like peptide-1 content and an increase in short-chain fatty acid content;additionally,muc2 mRNA expression level increased significantly(P<0.05).Furthermore,pasteurized A.muciniphila up-regulated mRNA expression levels of ampk,pi3k,akt as well as glycolytic genes gk and pfk in the liver while down-regulating mRNA expression levels of gluconeogenic gene pepck(P<0.05).(3)incubation results from primary liver and intestinal cells revealed that after pasteurized A.muciniphila treatment,there was a significant decrease in glucagon-like peptide-1 content within intestinal cells while simultaneously increasing gpr40 mRNA expression;furthermore,hepatocytes showed significantly increased mRNA expressions of glycolysis genes gk and pfk.In conclusion,high glucose diet increases the blood glucose levels,and causes liver and intestinal damage of C.carpio.The addition of exogenous pasteurized A.muciniphila increases the content of short chain fatty acids in C.carpio intestinal contents,inhibits intestinal secretion of glucagon-like peptide-1,alleviates the increase in blood glucose caused by high glucose diet,maintains glucose homeostasis.This research can provide the practical basis for the application of A.muciniphila as a probiotic in aquatic feed.