The Anti-obesity Effect And Potential Mechanism Of Fucoidan From Pearsonothuria Graeffei In HFD-fed Mice

ObjectiveIn recent years,the change of diet structure gave rise to the increasing prevalence of obesity year by year,which seriously endangers public health and causes a large number of obesity-related deaths every year.Fucoidans extracted from sea cucumber Pearsonothuria graeffei(Fuc-Pg)had a good anti-obesity effect,but its mechanism remained unclear.In this study,the mouse obesity model was established by high-fat diet(HFD),and different doses of Fuc-Pg were compared to explore the preventive effect and potential mechanism of Fuc-Pg on diet-induced obesity in mice.Methods1.Establishment of animal models and intervention grouping: 40 C57BL/6J mice were randomly divided into 5 groups(n=8)after one week of adaptive feeding.The normal Control group(Control group)was fed with normal diet,and the high fat model group was fed with high fat diet(HFD group),which was regard as the negative control group.Positive control group(S group)was fed with high fat diet and supplemented with simvastatin,with the dose of 20mg/kg/d;The low-dose Fuc-Pg group(Fuc-Pg-L group)was fed with high fat diet and supplemented with Fuc-Pg for intervention with the dose of 20mg/kg/d.Highdose Fuc-Pg group(Fuc-Pg-H group)was fed with high-fat diet and supplemented with Fuc-Pg for intervention with the dose was 80mg/kg/d.After 8 weeks of intervention,mice in each group were sacrificed after fasting for 12 hours.Blood samples,liver,adipose tissue,small intestine and colon of mice were collected,frozen with liquid nitrogen,and stored in the refrigerator at-80℃.2.Laboratory analysis: triglycerides(TG),total cholesterol(TC),low-density lipoprotein-cholesterol(LDL-C)and high-density lipoprotein-cholesterol(HDL-C)were measured with detection kit.Tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),CD14,toll-like receptor 4(TLR4),s CD36,apolipoprotein 48(Apo B 48)and apolipoprotein 100(Apo B 100)were detected by ELISA kit.The expression levels of CD36,ERK,p-ERK and FABP-1 in small intestine and NFκB,JNK,p-JNK and p-NFκB in liver and colon were detected by western blotting.3.The UPLC-TOF technique was used for untargeted metabolomics analysis of mouse colon feces.VIP and p values were used to screen differential metabolites in colon feces,and pathway analysis was performed for the screened differential metabolites.The correlation between the substances involved in tryptophan metabolism pathway and serum indexes was analyzed.Results1.Compared with Control group,the serum TG,TC,LDL-C,fasting blood glucose and insulin levels in HFD group were increased,GLP-1 levels were decreased,and insulin resistance was obvious.After high-dose Fuc-Pg intervention,the levels of TG,TC,HDLC,fasting blood glucose and insulin decreased,and the levels of GLP-1 increased.Fuc-Pg alleviated the dyslipidemia and insulin resistance caused by high-fat diet in mice.2.High-fat diet caused the disorder of lipid metabolism in the intestinal tract of mice,and the expressions of CD36,FABP-1 and p-ERK proteins in the small intestine were increased.The expressions of CD36,FABP-1 and p-ERK in the small intestine were inhibited by the intervention of Fuc-Pg.Fuc-Pg could inhibit the absorption of dietary fat in the intestine and promote the excretion of dietary fat.3.High-fat diet could lead to chronic inflammation in mice,and the serum levels of TNF-α,LPS and leptin inflammatory factor were increased,and the levels of antiinflammatory factor adiponectin were decreased.High-fat diet increased the levels of TNF-α,IL-6 and NLRP3 in the liver and activated the JNK/NFκB pathway in the liver and colon,leading to liver and colon inflammation.Fuc-Pg intervention could relieve inflammation,reduce inflammatory factors in serum and liver,and inhibit the activation of JNK/NFκB signaling pathway in liver and colon.4.High-fat diet could alter the composition of gut microbiota and cause changes in intestinal metabolites,which were associated with blood fat,blood sugar and inflammation.Fuc-Pg could promote the excretion of monoacylglycerol and relieve intestinal metabolic disorders induced by high fat diet through tryptophan metabolism pathway.ConclusionFuc-Pg could effectively prevent obesity induced by high fat diet,and alleviate lipid disorders induced by high fat diet,inhibit intestinal absorption of dietary fat,reduce the level of circulating inflammatory factors,relieve liver and colon inflammation,and regulate gut microbiota and intestinal metabolites.Fuc-Pg has a good preventive effect on obesity induced by high fat diet,and can relieve obesity induced by high fat diet,regulate intestinal lipid metabolism,relieve body inflammation,and regulate intestinal metabolites.