Toxicity And Susceptibility Of BDE-209 Exposure On BRL Cells With Insulin Resistance And Intervention Effect Of Grifola Frondosa Polysaccharide

Decabromodiphenyl ether(BDE-209)is a typical persistent organic pollutant,which widely exists in a variety of environmental media and human body,and has strong bioaccumulation and multisystem toxicity.Its toxic effects and potential health risks are worthy of attention.Type 2 diabetes mellitus(T2DM)is mainly characterized by insulin resistance(IR).Because the number of patients with T2DM is more than 90%of the total number of patients with diabetes mellitus,the health risk faced by this population has become a major problem in the world.Studies have shown that T2DM population is more sensitive to environmental pollutants exposure,but its susceptibility to toxicity caused by BDE-209 exposure has not been reported.Grifola frondosa polysaccharide has many biological activities such as hypoglycemia,immune regulation and antiviral,but whether it could improve the health risk of BDE-209 on T2DM population and the related mechanisms remains to be studied.In view of this,this paper takes IR-BRL cells as the research object to study the toxic effect of BDE-209 exposure on IR-BRL cells,analyze its susceptibility,and reveal its related molecular mechanism;The purified fraction of Grifola frondosa polysaccharide(GFP33)was prepared by column purification method,and its structure was analyzed;On this basis,the intervention effect and mechanism of GFP33 on metabolic toxicity of IR-BRL cells induced by BDE-209 were explored,so as to provide the basis for the prevention of metabolic toxicity of T2DM population induced by BDE-209 through nutritional intervention,which is of great significance to the health of T2DM population.The main research contents are as follows:(1)Study on the toxic effect,susceptibility and mechanism of BDE-209 on IR-BRL cells.IR-BRL cell model was established to study the effect of BDE-209 on indicators related to glucolipid metabolism and expression of proteins and genes related to insulin receptor signaling pathway in IR-BRL cells,and the susceptibility of IR-BRL to BDE-209 was analyzed.The results showed that BDE-209 could inhibit the glucose absorption of IR-BRL and BRL cells,increase the contents of TC and TG,and cause the disorder of glucolipid metabolism;It could increase the levels of AST,ALT and MDA,and cause hepatocyte injury;Mechanism studies showed that BDE-209 exposure could inhibit the transport of glucose and the synthesis of glycogen and fatty acid by affecting IRS-1/GLUT4 and IRS-1/PI3K/AKT/GSK-3β.At the same time,it could inhibit the proliferation and differentiation of cells by affecting the expression of Mek1/2,Erk1/2 and mTOR proteins and genes.Susceptibility analysis showed that there was a significant synergism interaction between establishment of IR model and the dose of BDE-209,which revealed that IR-BRL cells were more susceptible to the metabolic toxicity induced by BDE-209.(2)Purification and Primary structural characterization of Grifola frondosa polysaccharide.The crude polysaccharide of Grifola frondosa was purified by DEAE Sepharose fast flow and Sephacryl S-500.GC analysis showed that it was a homopolysaccharide composed of glucose;HPSEC-MALLS-RI showed that its Mw was 5.217×106 Da,MW/Mn=1.049,with good homogeneity;Methylation combined with GC-MS analysis showed that it was composed of two sugar residues,namely T-Glcp and 1,4-linked-Glcp,with a molar ratio of 1:6.179.(3)Study on the intervention effect and mechanism of GFP33 on the cytotoxicity of IR-BRL cells induced by BDE-209.IR-BRL cells exposed to BDE-209 was used to investigate the effects of GFP33 on the disorder of glucolipid metabolism and abnormal expression of proteins and genes related to insulin receptor signaling pathway and to reveal its intervention mechanism.The results showed that the prior intervention was the best way;GFP33 could improve the disorder of glucolipid metabolism induced by BDE-209 via promoting glucose absorption and reducing the contents of TC and TG;It could alleviate the hepatocyte injury induced by BDE-209 via reducing the levels of MDA,AST and ALT;The mechanism study showed that GFP33 could promote glucose absorption,the synthesis of glycogen and fatty acid via activating IRS-1/GLUT4 and IRS-1/PI3K/AKT/GSK-3β pathway;Through up regulating the expression of Mek1/2,Erk1/2 and mTOR proteins and genes,GFP33 could promote the proliferation and differentiation of IR-BRL cells,and then achieve its protective effect on the cytotoxicity induced by BDE-209.