The Research Of Four Bifidobacteria Strains Acting On Obesity In Rats Fed With High-fat Diet And Possible Mechanism

Chapter One:The effect of four bifidobacteria strains acting on serum lipid and obesity in rats fed with high-fat dietObjective:Our research used four strains of bifidobacteria separated from normal intestine of human to investigate the effect on blood lipid,blood glucose,adipokinesis,Intestinal floras and obesity in rats fed with high-fat diet.It was aimed to detect the different effect of bifidobactefia strains in order to select a strain of bifidobacteria which has effect on improving serum lipid and obesity and provide the based on for study of specific probiotics.Methods:48 SD rats were randomly divided into 6 groups.Group D Were normally fed,While GroupA,B,C,E,F were fed with high-fat diet and various bifidobacteria strains at the same time.Group B(L66-5),Group C (L75-4),Group E(M13-4),Group F(FS3-1-1-2),Group A is the model group.6 weeks later,all rats were executed.The effects of various bifidobacteria strains on blood lipid,blood glucose,adipopexis of rats in vivo were determined with body weight,OGTT,Lee's index,the weight of viscera fat,liver index,the lipid of liver and serum and serum insulin. The level of fatty and glycogen deposition in liver was observed using HE,Sudanâ…£,PAS staining.Microbial condition in large and small intestine contents were measured intestinal floras analyses.Results:The body weights decreased significantly in group B,F.The increment of body weight from 212.55g±18.54g in model group to 175.19g±41.24g(Group B),197.34±35.61(Group F)respectively.The Lee's score(in Group B,F)and liver score(Group C,E,F)were decreased in compared with the group A(P＜0.05).TG level of All groups of bifidobacteria strains were decreased obviously(P＜0.05),and also in group B,F of TCH(P＜0.05).The effect of various bifidobacteria strains on OGTT and INS in serum were little(P＞0.05).The level of fatty and glycogen deposition and fatty degeneration in liver which were reduced different degrees in groups interfered in by various bifidobacteria strains, especially group B,F,and at the same time,the adipose cell was reduced in size but increased in quantity.In intestinal floras analyses,the Lactobacillus in small intestine contents were 1.23±3.25(lg%)in group E, which were much lower than that of model group 7.48±3.04(lg%) (P＜0.05),however the bacteroides were increased to 9.02±4.02(lg%) compared with control group 6.88±1.03(lg%)(P＜0.05).Conclusion:(1)Feeding the SD rats with mixed high-fat feed formulas included of 25.17%fat and 16.52%protein for 6 weeks could established an alimentary obesity rat model.(2)bifidobacteria L66-5 strain and FS3-1-1-2 strain have reduced body weight,TG and TCH in serum,improved lipidoses in liver and viscera,and have effected on quantity and size of adipocyte and hepatic glycogen storage in rats fed with high fat diet.but no influence to serum glucose and insulin.(3)bifidobacteria M13-4 strain have increased body weight in rats fed with high-fat diet.However,it has improved serum TG and TCH and lipidoses in liver,no influence to hepatic glycogen storage and serum glucose and insulin.(4)No effect of bifidobacteria L75-4 strain on body weight in rats fed with high-fat diet.However,it has improved serum TG and TCH and lipidoses in liver,no influence to serum glucose and insulin secretion. Chapter Two:The study on the mechanism of these four bifidobacteria strains affecting to obesity in rats fed with high-fat dietObjective:To approach on the change of endocrine of adipocyte after entry organism of four bifidobacteria strains and the mechanism of its affecting on serum lipid and obesity.Observing the effect of four different strains of bifidobacterium on expression of the gene and protein of PPAR-α,PPAR-γ₁,PPAR-γ₂,TNF-α,ADIPOQ in liver,intestine,skeletal muscle,adipose tissue in rats fed with high-fat diet.Methods:all SD rat's tissue of left lobe of liver,small intestine side intestinal mucosa of ileocecal junctio,hind leg skeletal muscle,viscera adipose tissue were anatomized,then extracted the total RNA of all tissue and total protein of liver tissue.Measured the mRNA expression of PPAR-α, PPAR-γ₁,PPAR-γ₂ in all tissue and TNF-α,ADIPOQ in adipose tissue with RT-PCR.Western blotting analysis were employed to observe the effect four different bifidobacteria strains on the expression of PPAR-γprotein in liver.Results:(1)The expression of PPAR-αmRNA in liver tissue was increased significantly in groups of various bifidobacteria strains(P＜0.05),while it′s in intestinal mucosa were increased only in the group B and E (P＜0.05).(2)The expression of PPAR-γ₁ mRNA in liver tissue and intestinal mucosa were increased significantly in group C,E,F compared with the model group(P＜0.05),but it was no significant differences in group B (P＞0.05).(3)PPAR-γ₂ mRNA was specific expressed in adipose tissue where it expressed increased significantly in groups various bifidobacteria strains compared with the model group(P＜0.05),especially in group D and E(P＜0.01).Besides a little were been found in liver tissue of group E.(4)There was no significant discrepancy on expression of PPAR-αmRNA and PPAR-γ₁ mRNA in skeletal muscle and adipose tissue of each group(P＞0.05).(5)The expression of TNF-αmRNA in adipose tissue was decreased obviously in groups of B,C and F(P＜0.05),But the degree of decrease was a little in group E(P＞0.05).(6)There was no significant discrepancy on expression of ADIPOQ mRNA in adipose tissue of each group(P＞0.05).(7)The protein expression of PPAR-γin liver tissue was increased significantly in group C,E,F(P＜0.05),but it was no significant differences in group B(P＞0.05). Conclusion:(1)Bifidobacteria L66-5 strain has activated PPAR-αin liver and PPAR-γ₂ in adipose tissue and inhibited TNF-αresulted from adipose.(2)Bifidobacteria FS3-1-1-2 strain and L75-4 strain have activated PPAR-α,PPAR-γ₁ in liver and PPAR-γ₂ in adipose tissue.Besides its have reduced the secretion of TNF-αin adipose tissue.(3)Bifidobacteria M13-4 strain has increased the expression of PPAR-α,PPAR-γsignificantly in rats fed with high-fat diet.(4)There was no visible change of ADIPOQ in each group.