| ObjectiveTo study the effect of soybean peptide on lipid metabolism and anti-atherosclerosis resistance mechanism, and meanwhile to provide reliable theoretical basis on which used as a new type of soybean protein and bioactive peptides of the development plus its application in food, health care products, food additives, feed utilization and development of related industries.Methods1. The quantity effect of soybean peptide effect on blood lipid metabolism research on rats(1) Lipid metabolism experiment.50male Wistar rats which weight (200±10) g were divided into5groups at random by the weight and the level of serum cholesterol (TC):the normal control group, model group, and3groups with low, medium and high dose of soybean peptide. Normal control group eating a normal diet, the model group eating high fat diet that was special reciped, high, medium and low dose group of formula feed is on the basis of the high fat feed plus different dose of soybean peptide. After40days, each lipid index of rats was measured by blood.(2) Food intake and fecal excretion experiment. At the end trial period of3d, the rats were moved into metabolic cages which single cage breeding. The inputs and remaining amount forage of each rat were record accurately.Meanwhile, we should collect the feces of each rat for3d and dry to be tested, weight and calculate each group’s food intake and fecal excretion, compare it in different groups. (3) Impact of body weight and organ weight experiment. During the experiment, body weight of rats weighing once a week, after the end of the experiment, dissected the rats weight the liver, heart, kidney, and calculate to the ratio of the dirty body. The liver shoud be frozen (-20℃) to be seized, compare the difference between the body weight, organ weight and its coefficient of rats.2. Mechanisms of experimental study on soybean peptide to anti-atherosclerotic (1) Impact experiments of oxidized low density lipoprotein and lipase. After the end of the experiment, the rats were decapitated to take a sufficient amount of blood serum for test. LPL and HL concentration were tested by serum copper reagent method. The total lipase content was calculated.(Total lipase=LPL+HL). Content of lecithin lipid acyltransferase (LCAT) in liver tissue and low-density lipoprotein (ox-LDL) in serum were checked by ELISA assay.Then compare the differences between groups.(2) Impact experiments of endothelial factor. The separation of serum that above-mentioned is the sample. Content of prostaglandin (PGI2), thrombosis A2(TXA2) and endothelin1(ET-1) were checked by ELISA assay. Oxide (NO) content was tested by Nitrale reduetase methods. Then compare the differences between groups.(3) Impact experiments of apolipoprotein. Content of apolipoprotein A, B (Apo AI, Apo B) were checked by ELISA assay in serum.Then calculated the ratio of the two and compare the differences between the groups.(4) Impact experiments of fecal bile acid. Feces were dryed after the extraction. Fecal bile acid content was tested by Circulating enzymatic method. Then compare the differences between groups.(5) In vitro cholesterol micelles forming experiments. With fresh pig bile for the reaction system, a certain amount of cholesterol was added to the system,in addition to the blank pipe, others were added to different doses of soybean peptide solution, each dose had10parallel samples. Determination of free cholesterol levels after a certain reaction conditions. The content of cholesterol micelles was the amount of cholesterol added to the system minus the amount of free cholesterol in the precipitate. Inhibition rate (%)=(1-the content of the-containing soybean peptides tube cholesterol micelles/blank tube)*1003. The statistical methods. The experimental data were indicated in (x±s). Statistical analysis was performed using SPSS16.0software. The two groups were compared using the t test. Homogeneity of variance test and single-factor analysis of variance (One Way ANOVA) were used to compare among groups. Further pairwise comparisons between groups, used SNK test (Student-Newman-Keuls method) if the homogeneity of variance, if unequal variances, game howell test. P<0.05was considered statistically significant (significant difference).Results:1. Lipid metabolism experimental results.(1) Lipid metabolism results:Between Trial period, after high fat feed, serum TC of model group rats is1.77times that of the normal control group, TG1.58times. After t test analysis, model group was significantly higher than normal control group in TC and TG level (t<0.01). At final experiment time, compared with high-fat model group, middle, high dose group of TC, TG content were significantly lower (P<0.05, P<0.01); HDL-C content was Higher but no significant (P>0.05).(2)Food intake and fecal excretion experimental results. Each animal growth and development well. There is a steady increase in weight. Rats of High-fat model group eat less, but no significant (P>0.05). Differences of discharge excrement between each group have no statistical significance (P>0.05).(3) Impact of body weight and organ weight experiment results. During the experiment, the rats’weights gain steady. From the second weekend, weight of rats in middle, high dose group and normal group increased significantly, compared with high-fat model group (P<0.05, P<0.01). At final experiment, compared with high-fat model group, weight, liver, heart, kidney weight of middle, high dose group of rats significantly increased (P<0.05, P<0.01), liver,kidney ratio of high dose group is statistically different(P<0.05, P<0.01). 2. Functional mechanism of resistance to atherosclerosis on rats(1)At the final experiment, compared with high-fat model group, LPL, HL, total lipase, LCAT, inside the original NO and PGI2, Apo AI, fecal bile acid content in middle and high dose group were significantly increased (P<0.05, P<0.01); Apo AI/Apo B in high dose group was increased in statistically significantly(P<0.01); ox-LDL, ET-1, TXA2in middle and high dose group were decreased obviously (P<0.05, P<0.01). Apo B had no significant differences between groups (P>0.05).(2) When put in the reaction system with different dose of mixed soybean peptide, we found that each tube can inhibit cholesterol micelles formed, but the tube inhibition rate had no significant difference (P>0.05).Conclusion:1. Feeding rats with high fat after40days can induce rats to model fatty successfully.2. The forage content is4.050%and12.150%of soybean peptide mixed suspension can obviously decrease TC, TG, and increase to a certain degree of HDL-C in rats. According to’Technical specification for health food inspection and evaluation standards (2003edition)’, soybean peptide was provided with decreasing blood lipid.3. Mechanism of AS resistant in Soybean peptides may be:(1). Enhance the lipase and Apo A content in the blood, reduce the Apo B content, improve the body, especially the liver on lipoprotein transport, transformation, inhibit excessive deposition of fat particles from the sources;(2). Reduce the ox-LDL producing, with the purpose of reduce the foam cell formation, and decrease platelet adhesion, aggregation and thrombosis, in order to prevent atherosclerosis (AS).(3). Increase PGI2, NO and reduce TXA2, ET-1, in order to inhibit the injury to endothelial cells, and maintain normal physiological function for preventing the formation of the AS plaque.(4). Increase excretion of fecal bile acid, accelerates the transformation, clear, reduce blood fat levels of lipoprotein in vivo. |
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