Insights Into A Possible Mechanism Underlying The Connection Of Carbendazim Induced Hepatic Lipid Metabolism Disorder And Gut Microbiota Dysbiosis

There are trillions microbial cells in and on our body.The human gut harbors a wide range of microbes(the gut microbiota)which now regarded as an important organ and,makes great contributions to host nutrient metabolism and energy balance.The microbiota affects not only the degradation of complex dietary carbohydrates but also the development of host immune system and neural system.Carbendazim(CBZ),a systemic broad-spectrum benzimidazole fungicide,is world widely used to control fungal diseases.Although CBZ was classified as a low toxicity substance,it is possible environmental endocrine-disrupting chemicals(EDCs)exist in environment.The goal of this research is to reveal the potential hazard affect of CBZ to mice gut microbiota and lipid metabolism.To ensure the effects of CBZ to mice gut microbiota,ICR mice were orally treated with 100 and 500 mg/kg/day CBZ in food for 4 weeks.The results indicated that,the administration of CBZ relatively increase the mice body weight and,induced hepatic lipid metabolism disorder which was characterized by significant increases of hepatic lipid accumulation and triglyceride(TG)levels in mice.The serum cholesterol(TC),high-density lipoprotein(HDL),low-density lipoprotein(LDL),IL-1b and IL-6 levels also increased after CBZ exposure.Correspondingly,the relative mRNA levels of some key genes related to lipogenesis and TG synthesis increased significantly both in the liver and fat.Such as the mRNA levels of Fat,Acl1,Dgat1,Dgat2 and ApoC3 in the liver and the Srebp1 c,Acc,Acl1,Fas,Gpat and Dgat1 levels in the fat.Furthermore,the levels of bioaccumulation of CBZ in the liver and gut were very low as compared in the feces.At phylum level,the relative abundance of the Bacteroidetes decreased significantly in the feces after 5 days CBZ exposure.High throughput sequencing of the 16 S rRNA gene V3–V4 region revealed a significant reduction in richness and diversity of gut microbiota in the cecum of CBZ-treated mice.UniFrac principal coordinates analysis observed a marked shift of the gut microbiota structure in CBZ-treated mice away from that of the controls.More deeply,a total of 361 gut microbes(OTUs)were significant changed.The above data indicated that expose to CBZ in a relative high concentration indeed lead to mice gut microbiota dysbiosis and lipid metabolism disorder.To further ensure the relationship between CBZ-induced microbiota dysbiosis and hepatic lipid metabolism disorder in mice,male C57BL/6 mice were orally treated with low dose of CBZ(0.2,1,5 mg/kg/day)in drinking water for 14 weeks.Our results revealed that the administration of CBZ induced significant increases of body weight?liver weight and epididymal fat weight in mice.Correspondingly,the serum triglyceride(TG),TC,free fatty acid(FFA)and glucose levels also increased after CBZ exposure.Although high serum glucose level was observed,the blood insulin concentration was not changed obviously after CBZ exposure.The serum lipoprotein lipase(LPL),which played a fundamental role in fatty acid release from triglyceride,was decreased significantly.Moreover,the significant increased concentration of blood TNF-??IL-1??LCN2 means systemic inflammation in CBZ treated mice.In feces,at phylum level,the abundance of the Bacteroidetes decreased significantly after 1 week CBZ exposure and,a shift of the gut microbiota structure in CBZ-treated mice away from that of the controls.As a consequence of dysbiosis in gut,the production of acetate significant decreased and the butyrate relatively increased,and the gene levels of Gpr41 and Gpr43 were upregulated.Similarly,the changed microbiota downregulated the mRNA level of Fiaf(which works as an inhibitor of LPL activity)in ileum and then significant increase the activity of ileum LPL.The CBZ significant downregulated the gene levels related to hepatic TG synthesis and upregulated the mRNA levels of lipid storage in the fat.Final the dysbiosis in the gut leaded more microbes infect into the colon mucus which may be an important cause of colitis.Taken together,CBZ induced lipid metabolism disorder and gut dysbiosis in mice.The CBZ-induce gut microbiota changes promoted the food lipid absorption in mice intestine and finally,leaded hyperlipidemia and lipid metabolism disorder.