Study On The Effect Of Akkermansia Muciniphila On Glucose Metabolism Of Common Carp（cyprinus Carpio L.）

Common carp（Cyprinus carpio L.）is omnivorous fish that use carbohydrates better than other carnivorous fish,but their diabetic nature prevents them from making better use of the sugar in their diet.As a new type of probiotics,Akkermansia muciniphila（Akk）has been proved in human and mouse studies to have a good role in glucose metabolism,and pasteurized Akk also strongly improved glucose tolerance.As far as we know,there has failed to report on the study of Akk in fish.In this study,three hundred healthy common carp（26.5 ± 3.0g）with the same size were randomly divided into 4 groups in the feeding experiment,for the four groups: NC group（25% glucose）,NC+Akk group（25% glucose + 1×108 CFU/g Akk）,HG group（50% glucose）,HG+Akk group（50% glucose + 1×108 CFU/g Akk）,and each group had 3 replicates with 25 tails per barrel and cultured for 60 days.Feeding experiment was conducted to explore the effects of Akk on growth performance,glucose metabolism and intestinal microorganism composition of common carp,and short-term oral administration experiment was conducted to further verify which component of Akk plays a major role in regulating glucose metabolism of common carp.To provide reference for the application of Akk in fish.The results are as follows:（1）Regulation of Akk on growth performance,serum biochemical indices and tissue morphology of common carpCompared with the NC group,the weight gain rate（WGR）,specific growth rate（SGR）of the HG group were significantly decreased,indicating that the high sugar diet was not conducive to the growth of common carp.The specific growth rate,feed conversion ratio（FCR）,weight gain rate were not significantly changed when Akk was added to two kinds of sugar level diets,which indicated that Akk could not promote the growth of common carp.After the addition of Akk,the contents of blood glucose and triglyceride in the two diets decreased significantly,which indicated that Akk could reduce blood glucose and triglyceride.Intestinal mucin increased,villus height increased and intestinal wall thickened significantly after the addition of Akk.（2）Effects of Akk on the expression of enzyme activity genes related to glucose metabolism of common carpGlycogen assay results showed that Akk promoted muscle glycogen synthesis,but had no significant effect on liver glycogen synthesis.After the addition of Akk,the expression level of Na+/glucose co-transporter 1（SGLT1）and glucose transporter 2（GLUT2）in intestinal tract were increased;Basic feed feed,the m RNA expression level of glucokinase（GK）,phosphofructokinase（PFK）were increased;High sugar feed feed,the activity of phosphoenolpyruvate carboxykinase（PEPCK）was significantly decreased,while the activity of PFK was significantly increased in liver.There were no significant changes in metabolic genes related to glucose metabolism in muscle.（3）Regulation of intestinal microflora of common carp by AkkCompared with the NC group,the abundance of Firmicutes in the HG group was significantly increased at the phylum level,while the abundance of Vibrio in the HG group was significantly increased at the genus level.Akk significantly reduced the diversity and richness of the intestinal microflora of carp,significantly increased the abundance of Fusobacteria,Verrucomicrobia at the phylum level,and decreased the abundance of Firmicutes.At the genus level,Akk increased the abundance of Akkermansia,Cetobacterium and Prevotellaceae（P < 0.05）,and significantly decreased the abundance of Aeromonas,Pseudomonas and Vibrio（P < 0.05）.Akk reduces the metabolic function of the intestinal flora of common carp.（4）Effects of oral administration of Akk on glucose metabolism of common carpAkk and pasteurized Akk significantly reduced the postprandial TG content of common carp,and pasteurized Akk significantly reduced the preprandial TG content of common carp,but had no effect on the preprandial TG.The supernatant of Akk,pasteurized Akk,Akk significantly reduced the serum glucagonlike peptide 1b（GLP-1b）content of common carp after meal,but had no effect on the serum GLP-1a,GLP-1b content of common carp before meal.The results of premeal studies show that Akk and pasteurized Akk significantly reduced the m RNA expression level of glycogen synthase（GYS）,GLUT2 in liver.The results of the postprandial study showed that Akk significantly increased the expression level of GK,GYS in liver,pasteurized Akk significantly increased the expression level of GLUT2 in liver.In conclusion,Akk promotes the reduction of blood glucose content and triglyceride content of common carp fed with high sugar,promotes the expression of glycolysis related genes,inhibits the expression of gluconeogenesis related genes,and reduces the diversity and richness of intestinal microflora.Oral administration experiment has shown that pasteurized Akk have a stronger role in regulating glucose metabolism.The regulation effect of Akk on glucose metabolism of common carp is similar to that of mammals,but the results of the study on intestinal flora are different from that of mammals,which may be caused by species differences and environmental strains,etc.The specific reasons still need further confirmation.In the future,it can be invoked as additive to adjust feed formulation and improve glucose metabolism of aquatic animals.