| According to the report on nutrition and chronic diseases of Chinese residents(2015),the overall prevalence of dyslipidemia in adults in China is 40.40%,showing a trend of rejuvenation.Hyperlipidemia is an important risk factor of atherosclerosis,coronary heart disease,stroke,myocardial infarction and many other diseases.Although taking lipid-lowering drugs can alleviate symptoms to some extent,it will have some side effects if taken for a long time.Therefore,it is urgent to find active substances with mild efficacy and low toxic side effects for the prevention and treatment of hyperlipidemia.In recent years,many researchers have reported the biological activities of Flammulina velutipes polysaccharide,such as immune regulation,antioxidation and liver protection.However,although there are few reports on the hypolipidemic function of Flammulina velutipes,its mechanism is not yet clear.Gut microbiota plays a vital role in human health.A large number of studies have proved that gut microbiota is closely related to the prevention and development of diseases.Using probiotics and prebiotics to regulate gut microbiota to prevent or cure diseases has the characteristics of small side effects and significant effects.This study used polysaccharide extracted from Flammulina velutipes,and using cell model,zebrafish model,high-fat diet mouse model and fecal microbiota transplantation to clarify the hypolipidemic function of Flammulina velutipes.The correlation between the lipid-lowering effect of Flammulina velutipes polysaccharide and gut microbiota has also been explored.The purpose of this study is to provide some experimental data for the mechanism of Flammulina velutipes to improve hyperlipidemia through gut microbiota,and to provide new ideas for the further development of functional foods and health products with the function of preventing hyperlipidemia.The following are the main results of this paper:1.Preliminary study is proved that FVP60 have good effect on reducing blood lipid.FVP30 and FVP60 were extracted from the fruiting body of Flammulina velutipes by water extraction and alcohol precipitation.The content of the two polysaccharideswas 23.77% and 47.37% respectively tested by the method of phenol-sulfuric acid.The results of RAW264.7 cell lipid accumulation model showed that FVP60 with a concentration of 400 ?g/m L had a better inhibition effect on the formation of lipid deposition cells induced by oxidized low density lipoprotein(Ox-LDL)than FVP30 with the same concentration.It was further verified in hyperlipidemia model of zebrafish that FVP60 of 100 ?g/m L and 200 ?g/m L reduced the lipid accumulation level of zebrafish to 40.00 ± 6.00% and 10.00 ± 2.00% respectively,and there was almost no lipid accumulation in FVP60 of 400 ?g/m L.The results showed that FVP60 could reduce the lipid accumulation level of zebrafish blood vessels in a dose-dependent manner.2.FVP60 can improve the physiological indexes of hyperlipidemic mice.The experiment of hyperlipidemia mice showed that FVP60 had a certain improvement hyperlipidemia.During the whole experiment,the levels of total cholesterol(TC)and low-density lipoprotein cholesterol(LDL-C)in serum of mice on high-fat diet(HFD)increased extremely significantly compared with those on natural diet(ND).The level of high-density lipoprotein cholesterol(HDL-C)decreased significantly in the early stage and showed extremely significant decrease in the later stage.Compared with HFD group,FVP60 intervention group can significantly reduce the level of LDL-C in low-dose polysaccharide HFDL group,significantly or extremely significantly reduce the level of TC(P < 0.05)and LDL-C(P < 0.01)in medium-dose polysaccharide HFDM group,significantly reduce the level of LDL-C and significantly increase the level of HDL-C in high-dose polysaccharide HFDH group.At the later stage of the experiment,each polysaccharide dose group could continuously improve the serological indexes of hyperlipidemic mice.In addition,FVP60 can reduce the level of serum AST and ALT,but there is no significant difference.Besides,FVP60 can improve the pathological changes of the liver,reduce the fat drop vacuoles formed by the high fat diet and have a certain protective effect on the liver.In terms of liver index,high fat diet significantly or extremely significantly increased the hepatic levels of TC(P < 0.01),triglycerides(TG)(P < 0.05)and LDL-C(P < 0.05).The levels of TC and LDL-C in liver fat could be reduced by FVP60 with low,medium and high dose.High dose FVP60 can also significantly increase the content of lecithin cholesterol acyltransferase(LCAT)in liver.3.FVP60 can change the structure of gut microbiota in hyperlipidemic mice.FVP60 can regulate the disturbance of gut microbiota in hyperlipidemic mice and increase the similarity between to normal diet group.At the level of phylum,high doseFVP60 can significantly reduce the proportion of Fimicutes and increase the proportion of Bacteroides.At the level of genus,FVP60 with low,medium and high dose group can reduce the levels of Staphylococcus,Ruminococcus,[Ruminococcus],Corynebacterium,Dorea,Brevibacterium and Streptococcus compared with HFD group.In addition,HFDL and HFDM can significantly reduce the level of Brachycharacter,HFDH can also significantly reduce the level of Lactobacillus and significantly increase the level of Oscillospira.4.After fecal bacteria transplantation,hyperlipidemia was improved and the structure of gut microbiota was changed.After 4 weeks of fecal microbiota transplantation,the level of serum TC in HFDHR group was significantly lower than that of HFDR group.At the end of the 8th week,compared with HFDR group,HFDHR group could extremely decrease the level of TC and LDL-C,significantly increase the level of serum HDL-C and decrease the level of AST and ALT,and the level of AST was extremely significantly different from that of HFDR group.In addition,compared with HFDR group,HFDHR group can make the liver cells return to normal shape,reduce the production of lipid droplets and vacuoles,which has a certain role in protecting the liver.Liver indexes showed that compared with HFDR group,the level of TG(P < 0.05)and LDL-C(P < 0.01)in HFDHR group could also be significantly reduced.The results of 16 S r RNA sequencing showed that the structure of gut microbiota had changed significantly between the two groups.The levels of Ruminococcus,Coprococcus and Odoribacter in HFDHR group were higher than those in HFDR group,while the levels of Lactobacillus,Akkermansia and Biofidobacterium were lower.5.There is a correlation between the changes of gut microbiota and the indexes of hyperlipidemiaThe results of random forest analysis showed that the bacteria with different changes of Flammulina velutipes polysaccharide played a vital role in each group.Flammulina velutipes polysaccharide can significantly up-regulate or down-regulate the gut microbiota through random forest analysis to find that each genus does indeed play a very important role in species ranking.The correlation analysis showed that there were different degrees of correlation between gut bacteria and the indexes related to hyperlipidemia.It is worth mentioning,the significantly increased bacteria of Oscillospira had a significant negative correlation with the serum TG level;the Ruminococcus level had a significant negative correlation with the serum TC and theliver LDL-C level;the Odoribacter level had a significant negative correlation with the serum LDL-C(P < 0.01),the liver TG(P < 0.01),and the LDL-C(P < 0.05),and the level of HDL-C was significantly or extremely significantly positively correlated with serum HDL-C and LCAT. |
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