Effects Of Dietary Curcumin Supplementation On Glucose And Lipid Metabolism And Gut Microbiota Of The High-fat-induced Obesity Mice

The target of this study was to investigate the effects of high-fat induction and curcumin(Cur)intake on mice adipose tissue composition,glucose and lipid metabolism,and gut microbiota construction and its potential mechanism of action.Curcumin is a natural polyphenol that has a good effect on the metabolic disorders induced by high-fat diet,but its exact mechanism remains to be determined.This study explored the effect of the FNDC5/irisin signaling pathway on the metabolism of brown adipose tissue and white adipose tissue in obese mice,and investigated whether the metabolic adaptations resulting from curcumin supplementation were mediated by the gut microbiota in high-fat diet fed obese mice.30 Six-week-old male C57BL/6N male mice were randomly divided into three groups(n = 10 per group)briefly belows: lowfat diet(LFD),high-fat diet(HFD)and high-fat replenished with 0.2% curcumin group(HFD + Cur).The mice serum indicators,insulin sensitivity,liver metabolism,lipid metabolism,gut microbiota composition and short-chain fatty acid content were determined.The results showed that curcumin alleviated liver steatosis,inhibited the expression of pro-inflammatory cytokines and inflammatory proteins,improved insulin signaling and reduced the inflammatory response in HFD mice.In addition,curcumin regulated downstream signaling pathways(ERK/p38 MAPK phosphorylation)through the FNDC5/irisin signaling pathway to enhance brown adipose tissue metabolism and white adipose tissue browning.More importantly,curcumin reduced the ratio of Firmicutes/Bacteroidetes,increased the abundance of certain short-chain fatty acidproducing bacteria,increased the short-chain fatty acid content of the caecal and colon,and regulated the composition of the gut microbiota,improved gut microbiota imbalance.In summary,dietary curcumin supplementation of the high-fat-induced obesity mice could significantly improve the insulin sensitivity,and reduce the effects of high-fat diets on the liver and lipid metabolism.The mechanism may be related to the regulation of FNDC5/irisin signaling pathway,the diversity of mice gut microbiota composition and the content of short-chain fatty acids for curcumin-induced.