阿克曼菌对鲤糖代谢的调控作用研究

目的]本试验旨在探究巴氏灭活的阿克曼菌（Pasteurized Akkermansia muciniphila，P-Akk）调控鲤（Cyprinus carpio L.）糖代谢的分子机制。方法]本研究通过不同糖水平（20%、30%、40%、50%葡萄糖）试验，探究鲤（10.5±1 g）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（Akkermansia muciniphila，Akk）定植的时空变化；在不同糖水平试验基础上，设置40%葡萄糖和三个不同浓度P-Akk（108 cfu/g P-Akk、109 cfu/g P-Akk、1010 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、肠细胞试验，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]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（P < 0.05），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（P < 0.05），但8周时无显著性差异（P > 0.05）。（2）P-Akk处理后，鲤血清中葡萄糖、GLP-1含量显著减少（P < 0.05）；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（P < 0.05）；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（P < 0.05）。（3）原代肝、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（P < 0.05），而gpr40的mRNA表达量升高；此外肝细胞中糖酵解基因gk、pfk mRNA表达量显著升高。结论]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。意义]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。

The regulation mechanism of Akkermansia Muciniphila on glucose metabolism of the common carp (Cyprinus carpio L.)

Research background] 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 Akkermansia muciniphila regulates glucose metabolism in fish remains unclear. Objective] To investigate the molecular mechanism of pasteurized Akkermansia muciniphila regulating glucose metabolism in common carp (Cyprinus carpio L.). Method] 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 Akkermansia muciniphila colonization at 4 and 8 weeks of Cyprinus carpio L (10.5±1 g). Based on the different sugar concentration tests, groups with a glucose level of 40% and three varying concentrations of pasteurized Akkermansia muciniphila (108 cfu/g, 109 cfu/g, 1010 cfu/g) were established. The regulation of glucose metabolism and glucagon-like peptide-1 in carp (16.38±0.39 g) after four weeks of pasteurized Akkermansia muciniphila supplementation was explored. Additionally, the regulatory mechanism of intestinal Akkermansia muciniphila and glucagon-like peptide-1 on carp''s glucose metabolism under different glucose levels was investigated through experiments involving primary liver and intestinal cells incubated with pasteurized Akkermansia muciniphila. Results] The results demonstrated the following findings: (1) With an increase in dietary glucose content, there was a significant decrease in serum glucagon-like peptide-1b levels (P <0.05). (2) Following pasteurized Akkermansia 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 Akkermansia 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 Akkermansia 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. Conclusion] In conclusion, high glucose diet increases the blood glucose levels, and causes liver and intestinal damage of common carp. The addition of exogenous pasteurized Akkermansia muciniphila increases the content of short chain fatty acids in common carp 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 Akkermansia muciniphila as a probiotic in aquatic feed.