Effects Of Microcystin-LR On Intestinal Flora In Mice

Microcystins(MCs)are a class of monocyclic heptapeptide toxins produced by cyanobacteria.MCs can cause severe intestinal damage through drinking water,aquatic products or recreational activities.However,the exact mechanism of intestinal damage caused by MCs is unclear.The gut microbiota is one of the most important components of the ntestine,guand MCs are the first to contact the intestinal flora intestine,Therefore,this paper aims to study the mechanism of gut microbiota in intestinal damage induced by MCs.In this study,mice were gavaged to MC-LR(L stands for leucine and R stands for arginine)for 8-week.The dosage of MC-LR were 0 and 400 μg/kg,respectively.During the experiment,there was no death in the mice,and no significant change in body weight,activity or coat color.However,histopathological changes of the colon showed inflammatory cell infiltration,intestinal mucosal exfoliation,partial crypt structure destruction,and thinning of the intestinal wall.The above results indicate that a mouse model of intestinal damage induced by MC-LR was successfully established.In this study,high-throughput sequencing of colonic contents was performed to investigate the effect of MC-LR on colonic gut microbiota.It was found that MC-LR significantly reduced the alpha diversity of colonic microbiota.At the phylum level,MC-LR decreased the abundance of Candidatus Saccharibacteria and increased the abundance of pathogenic bacteria such as Proteobacteria,Deferribactere and Spirochaetes;at the genus level,MC-LR decreased the abundance of short-chain fatty acid-producing bacteria which could promote inflammation.At the same time,the functional prediction of colonic microbiota showed that compared with the control group,MC-LR decreased amino acid metabolism,energy metabolism,nucleic acid metabolism,glycan biosynthesis metabolism,and cofactor and vitamin metabolism of intestinal microbiota,and lipid metabolism and xenobiotic biodegradation increased.Particularly,MC-LR caused an increase in the functional abundance of intestinal-related diseases.The above results show that MC-LR led to intestinal damage and suffer from various intestinal diseases through changes in the phylum,genus or potential function level microorganisms.In summary,MC-LR can decrease the alpha diversity of intestinal microbiota and change the composition and function of microbiota,which cause intestinal microbial ecological imbalance and increasing the risk of body damage and disease.This study explains the mechanism of gut microbiota in intestinal damage caused by MC-LR,and will provide new research ideas for revealing other toxicity caused by MC-LR.