| Obesity is the result of long-term imbalance in energy intake and expenditure caused by the interaction between genetic susceptibility and environmental factors(nutritional,physiological,social),and its prevalence has increased significantly in the past 40 years.Sargassum fusiforme is a kind of medicinal and edible seaweed,in which Sargassum fusiforme fucoidan is one of the main active ingredients of Sargassum fusiforme,with a wide range of medicinal functions.In this paper,Sargassum fusiforme fucoidan(Fuc)was used as the experimental material,and obese mice induced by a high-fat and high-fructose(HFHF)diet were used as a research model to explore the intervention effect of Sargassum fusiforme fucoidan on the induction of C57BL/6J by a high-fat and high-fructose diet,and preliminary reveals its possible mechanism.The results are shown below:(1)Fuc significantly ameliorated the weight gain induced by a high-fat,high-fructose diet in mice and significantly reduce the accumulation of fat in various parts.H&E staining of gonadal adipose tissue and liver tissue showed that Fuc significantly improved liver steatosis,reduced inflammatory cell infiltration,significantly reduced adipocyte volume and relatively increased number,reduced serum TG,TC,LDL-C,FFA levels and Fuc significantly enhanced the protein expression level of p-AKT(Ser473)in adipose tissue.In addition,Fuc significantly enhanced the expression of Atgl and Hsl genes related to lipid catabolism in adipose tissue,but did not inhibit the expression of Srebp-1c,Acc,Fasn and Gpat genes related to lipid anabolism in liver tissue and Fuc did not significantly affect the expression of Ppara and Cpt1 a,genes related to fatty acid β-oxidation in liver and muscle tissues.(2)Fuc significantly increased energy expenditure but did not decrease energy intake in HFHF diet-induced obese mice.Further studies revealed that Fuc significantly enhanced the expression of the thermogenic genes Ucp1,Prdm16,Pgc-1a,Cidea,Elovl3 and Cox8 b in brown adipose tissue and white adipose tissue,as well as the expression of ATPsyn,COXIv,Cytc,some of the genes that make up the mitochondrial electron transport chain.In addition,Fuc reduced the size and relative number of lipid droplets in brown adipose tissue.(3)By 16 s rRNA high-throughput sequencing,the gut microbiota of mice in the high-fat,high-fructose(HFHF)group differed significantly from that of mice in the normal control(NCD)group,and the diversity and abundance of gut microbiota were significantly reduced,while the gut microbiota composition of mice in the Fuc intervention group was similar to that of the NCD group.Fuc significantly decreased the ratio of Firmicute/Bacteroidete,increased the relative abundance of beneficial bacteria such as Butyricoccus,Ruminococcaceae and decreased the relative abundance of harmful bacteria such as Helicobater.(4)The experiments in the pseudo-sterile mouse model showed that Fuc did not significantly inhibit weight gain in pseudo-sterile mice fed the HFHF diet,nor did it significantly reduce fat accumulation and liver weight,fasting blood glucose,fasting insulin content and lipid indexes were not significantly improved,Fuc did not significantly affect the expression of thermogenesis-related genes Ucp1 and Pgc-1a in brown adipose tissue and white adipose tissue.In conclusion,Sargassum fusiforme fucoidan has a good intervention effect on obesity in HFHF diet-induced mice.The mechanism of action may be through remodelling the gut micorobiota,activating the activity of brown adipose tissue,increasing energy expenditure,affecting glucolipid metabolism and limiting the weight gain induced by high-fat,high-fructose diet. |
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