Serum Cholesterol Concentrations In Rats Research Articles

Karaya root saponin exerts a hypocholesterolemic response in rats fed a high-cholesterol diet

Different sources of saponins are known to have hypocholesterolemic activity with varying degrees of efficacy. We hypothesize that karaya root saponin would efficiently reduce cholesterol. The aim of this study is to examine the comparative hypocholesterolemic effect of karaya root saponin in rats fed a high-cholesterol diet. Sixty male Wister-Imamichi rats were divided into 5 groups of 12 rats each constituting of the following: control group, soybean saponin-supplemented group, karaya root saponin-supplemented group, quillaja saponin-supplemented group, and tea saponin-supplemented group. Compared with the control diet, both the karaya root- and quillaja saponin-supplemented diets significantly reduced (P < .05) serum cholesterol and atherogenic index. Karaya root saponin significantly increased the serum high-density lipoprotein cholesterol, high-density lipoprotein cholesterol/cholesterol ratio, and fecal cholesterol concentrations (P < .05). The triacylglycerol concentration was significantly reduced only in the quillaja saponin-supplemented rats (P < .05). All the tea, soybean, karaya root, and quillaja saponins significantly reduced low-density lipoprotein cholesterol, and the greatest reduction was observed with karaya root saponin. Highest fecal bile acid concentration was found with quillaja saponin, whereas highest liver bile acid concentration was observed with karaya root saponin-supplemented rats (P < .05). These results collectively suggest that karaya root saponin can efficiently reduce serum cholesterol concentration in rats.

Serum Cholesterol-Lowering Effect of Apple Polyphenols in Healthy Subjects

We performed a clinical study using healthy male and female subjects who had slightly elevated cholesterol levels in their serum to examine the effects of food tablets containing apple polyphenols (Applephenon®), which are effective for improving serum cholesterol concentrations in rats, on lipid metabolism in humans. The total period of this study was four weeks and we obtained blood samples at week 0 and week 4. Total cholesterol levels of the intervention groups decreased significantly and dose-dependently compared with that of the control group. We also found LDL-cholesterol decreased significantly and HDL-cholesterol increased. No abnormalities were detected in biochemical examinations of any of the subjects during the test period. We concluded that the study product is useful as a food additive that improves serum cholesterol concentrations. Such improvement is expected to decrease the risk of atherosclerosis for people with a slightly elevated total cholesterol level.

Effects of structured lipids containing eicosapentaenoic or docosahexaenoic acid and caprylic acid on serum and liver lipid profiles in rats

The physiological activity and effect on lipid metabolism of four types of structured lipids (SLs), that contain caprylic acid (C8) and either eicosapentaenoic (EPA) or docosahesaenoic acid (DHA), were evaluated in male Wistar rats fed experimental diets containing 7% (wt %) of each SL and 3% (wt %) soybean oil for 28 days. Control rats were fed a diet containing 10% (wt %) soybean oil. The relative perirenal adipose tissue weights of rats fed D-8-8 and 8-D-8 diets were significantly lower than those of other groups. We observed significantly lower serum cholesterol concentrations in rats fed SLs than those of control group over experimental period. The serum lipids concentrations in rats fed diets containing SLs were significantly lower P < 0.05) than those of soybean oil group. The fatty acid compositions of WAT did not reflect the structural differences in the triglyceride. These results suggest that the physiological effects of the SLs used in this study were due to the fatty acids rather than the structural specificity. Therefore, further study will be needed to ascertain the most desirable structural configuration.

EFFECT OF DIETARY MILK CREAM AND EGG YOLK FAT ON SERUM AND LIVER LIPID PROFILE IN RATS

ABSTRACT Influence of dietary fat from milk and egg yolk on serum and liver lipid profile was studied in rats. Rats fed milk fat at 5% level for 8 weeks showed a 17% decrease in serum cholesterol and 31% decrease in triacylglycerol compared to the control group of rats fed groundnut oil (GNO). Liver cholesterol was decreased by 20% in the milk fed group. There was no difference in serum cholesterol concentration of rats fed egg yolk compared to the control animals. However, triacylglycerol and phospholipids in serum of rats fed egg yolk were decreased by 20 and 24%, respectively. In another set of experiments animals were rendered hypercholesterolemic by feeding a diet containing 0.5% cholesterol. Addition of milk fat in the diet decreased serum and liver cholesterol by 11 and 17%, respectively, compared to rats fed on a control diet. Similarly, triacylglycerols were decreased by 23 and 8%, respectively, in serum and liver of animals given

Resistant starches of beans reduce the serum cholesterol concentration in rats.

We examined the effects of the resistant starches of adzuki (Vigna angularis), kintoki (Phaseolus vulgaris, variety), and tebou (P. vulgaris, variety) beans on the lipid metabolism in rats. Rats were fed a cholesterol-free diet with 25 g of cornstarch (CS)/100 g diet, 25 g of adzuki starch (AS)/100 g diet, 25 g of kintoki starch (KS)/100 g diet, or 25 g of tebou starch (TS)/100 g diet for 4 wk. The cecal contents in the TS group were significantly higher than those in the CS and KS groups. There were no significant differences in body weight or food intake among the groups. The relative liver weight in the CS group was significantly greater than that of the AS, KS, and TS groups. The serum total cholesterol, VLDL+IDL+LDL-cholesterol, and triglyceride concentrations in the AS, KS, and TS groups were significantly lower than those in the CS group throughout the feeding period. Though the total hepatic cholesterol concentration in the TS group was significantly higher than that in the KS group, there were no significant differences between the CS and other starch groups. The cecal pH value in the CS group was significantly higher than that of the bean starch groups. The cecal butyric acid concentrations in the AS, KS, and TS groups were significantly higher than that in the CS group, and the cecal total short-chain fatty acid (SCFA) concentrations in the AS and TS groups were significantly higher than those of the CS group. The fecal cholesterol excretion of the AS, KS, and TS groups were significantly higher than that in the CS group. The fecal coprostanol excretion in the AS group was significantly higher than that in the CS group. There was a negative correlation between the serum VLDL+IDL+LDL-cholesterol concentration and fecal neutral steroid excretion (r = -0.664, p < 0.001) in the present experiment. Furthermore, the cecal total SCFA concentration was negatively correlated with the serum VLDL+IDL+LDL-cholesterol concentration (r = -0.665, p < 0.001) and positively correlated with fecal neutral steroid excretion (r = 0.481, p < 0.05). The cecal butyric acid level was also negatively correlated with the serum VLDL+IDL+LDL-cholesterol concentration (r = -0.609, p < 0.01) and positively correlated with fecal neutral steroid excretion (r = 0.658, p < 0.001). The results suggest that AS, KS, and TS elevate cecal SCFA concentration, in particular butyric acid concentration, and fecal neutral sterol excretion, and lower the serum total cholesterol level.

Effect of phytate in soy protein on the serum and liver cholesterol levels and liver fatty acid profile in rats.

Dietary soy protein, in comparison with casein, generally lowers the serum cholesterol concentration in rats fed on a cholesterol-enriched diet, while mixed results were observed in rats fed on a diet free of cholesterol. Soy protein also suppresses the conversion of linoleic acid to arachidonic acid in the rat liver. The present study examines whether phytate, a minor component of a soy protein isolate, is responsible for these beneficial effects of soy protein. Weanling male rats were fed for 4 weeks on a purified diet containing a 20% level of protein (either casein (CAS), soy protein (SOY), phytate-depleted SOY (PDSOY) or phytate-replenished PDSOY (PRSOY)) and cholesterol (0 or 0.5%). The dietary protein source and phytate level only affected the serum and liver cholesterol concentrations when the animals were fed on the cholesterol-enriched diet, being significantly lower in those rats fed on the SOY and PRSOY diets than in those fed on the CAS diet, while the concentrations in the rats fed on the PDSOY diet were intermediate. When the animals were fed on the cholesterol-free diet, the ratio of (20:3n-6 + 20:4n-6)/18:2n-6 in liver phosphatidylcholine, a delta6 desaturation index, was significantly lower in the SOY diet group than in the CAS, PDSOY and PRSOY diet groups. Dietary cholesterol significantly depressed the ratio, but neither depletion nor replenishment of phytate affected the ratio. These results suggest that phytate in soy protein played a limited role in the cholesterol-lowering effect of soy protein and was not involved in the metabolism of linoleic acid.

Nutritional value of the marine invertebrates Anemonia viridis and Haliothis tuberculata and effects on serum cholesterol concentration in rats☆

The purpose of this study was to determine the nutritional value of diets with protein from two marine species ( Haliotis tuberculata and Anemonia viridis) as compared to a high-quality protein reference based on casein or casein supplemented with olive oil. We also investigated the effects of these diets on serum lipid levels. Male rats were fed these diets for 23 days. Protein quality indicators (true digestibility, net protein utilization, biological value) were similar to those obtained for casein-based feeds except for lower true digestibility and net protein utilization values for the Anemonia viridis feed. HDL-cholesterol level was significantly higher (p < 0.05) in the groups fed marine species or casein supplemented with olive oil than in the casein group. Total-cholesterol level was higher in the group fed Haliotis tuberculata fed than in the other groups. These results suggest that these marine species are a good protein source, and that they may have positive effects on serum cholesterol level.

絹フィブロイン起泡粉末の給与がラットの血清コレステロール濃度に及ぼす影響

スポンジケーキなどの製造の際, 起泡素材として利用可能なフィブロイン溶液から起泡を製造し, その乾燥粉末 (フィブロイン起泡粉末) の給与がコレステロール添加食あるいは無添加食ラットの血清・肝臓脂質濃度に及ぼす影響について検討した。フィブロイン起泡粉末の人工消化率は11-25%と低く, またその給与はコレステロール添加食給与によるラットの血清総コレステロール濃度の上昇を有意に抑制し, 動脈硬化指数の上昇傾向を抑制する傾向にあった。また, 肝臓総コレステロール濃度もコレステロール添加食の場合, フィブロイン起泡粉末の給与によって低下する傾向にあった。糞排泄量および胆汁酸排泄量はコレステロール無添加食, 添加食のいずれの場合においてもフィブロイン起泡粉末の給与によって, それぞれ, 有意な増加, 増加傾向を示した。フィブロイン起泡粉末による胆汁酸の排泄量の増加は血清コレステロール低下作用の一部が, フィブロイン起泡粉末の未消化部分による胆汁酸排泄促進作用による可能性を示唆した。

Rice Protein Isolates Produced by the Two Different Methods Lower Serum Cholesterol Concentration in Rats Compared with Casein

Highly purified rice protein isolates (RPI) were prepared by an alkaline extraction–acid precipitation method (E-RPI) and by an α-amylase treatment to remove starch (T-RPI). Biological values of these RPI were significantly lower than that of casein. Serum cholesterol concentrations were compared among groups of rats fed (per kg diet) 200, 300 or 400 g E-RPI, 400 g T-RPI, 250 or 400 g casein kg−1 or 400 g soya bean protein isolate (SPI). With all the diets containing 400 g protein kg−1 diet, growth rates of rats were the same. At this level, E-RPI, T-RPI and SPI diets produced significantly lower serum cholesterol concentrations than the casein diet. Faecal bile acid plus neutral steroid excre-tion was significantly higher in rats fed the 400 g kg−1 T-RPI or 400 g kg−1 SPIdiets compared with rats fed the 400 g kg−1 casein diet. On the other hand, the 400 g kg−1 E-RPI diet did not increase steroid excretion. Plasma cholesterol concentrations in rats fed diets with amino acid mixtures simulating SPI and E-RPI were also significantly lower than that of rats fed the diet with an amino acid mixture simulating casein even though the faecal excretions of total bile acids were the same amongst groups. These results support the view that RPI are hypocholesterolaemic relative to casein and at least the hypocholesterolaemic effects of E-RPI would be independent of interruption of the enterohepatic circulation of endogenous steroids.

高コレステロール飼料を摂取させたラットの血清中コレステロール濃度に及ぼす発酵乳の影響

Serum cholesterol concentrations of rats fed high-cholesterol diets containing skim milk or cultured milks were estimated periodically during 12 days. Several kinds of cultured milks could inhibit the increasing of serum cholesterol concentrations in rats throughout the experimental period compared with skim milk. It was found that this inhibiting ability depended mainly on the specificities of strains, not on the specificities of species. A part of inhibiting mechanism against the increasing serum cholesterol concentrations was analysed using L. acidophilus SBT 2056 (LA 2056) which was selected as most effective one among all strains examined. Feeding the LA 2056 cultured milk resulted in the significant increase of sterol concentrations in bile and feces and also the activity of hepatic cholesterol 7α hydroxylase. The LA 2056 cells had a inhibitory effect against cholesterol micelle absorption from intestines. On the other hand, there was no apparent stimulation effect in the whey fraction of LA 2056 cultured milk on the production of bile acids in primaly cultured rat hepatocytes. From these results, it was supposed that the inhibition effect of LA 2056 cultured milk against increasing of serum cholesterol concentrations in rats was caused partly by the bacterial cells.

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ラットの血清コレステロール濃度に及ぼす緑葉タンパク質給与の影響

ラットの血清コレステロール濃度に及ぼす緑葉タンパク質給与の影響

Colchicine reduces proteinuria in passive Heymann nephritis.

Colchicine was given to rats in the heterologous phase of passive Heymann nephritis to see whether this drug could reduce proteinuria. Treatment with 0.06 mg/day for 14 days caused significant reductions in proteinuria and albuminuria. Administration of dimethyl sulfoxide (DMSO) alone or in combination with colchicine also reduced protein and albumin excretion. In a long-term experiment, rats treated with colchicine had significantly less proteinuria. After stopping therapy, urine protein excretion was similar to controls. No differences in glomerular C3 and IgG deposition were found between treated and control rats 24 h, 3,7 and 14 days after immunization. Depressed serum C3 levels were measured at 24 h in colchicine-treated rats. No difference in serum-circulating immune complexes was detected between the two groups. Concurrent administration of indomethacin and colchicine to rats with passive Heymann nephritis (PHN) partially reversed the reduction in proteinuria and albuminuria seen in rats treated with colchicine alone. The G.F.R, however, was significantly reduced in colchicine-treated rats as well as in rats treated with colchicine and indomethacin. Serum cholesterol and triglyceride levels were significantly lower in colchicine-treated rats than in controls. Serum cholesterol concentrations in rats given both colchicine and indomethacin were similar to control values. These findings suggest that colchicine reduces urine protein and albumin excretion, and hyperlipidemia in PHN. The finding that indomethacin partially blocks the effects of colchicine suggests that renal prostaglandin stimulation by colchicine may have been involved in the reduction in proteinuria.

Stability of serum cholesterol concentration in rats after injection of deoxyribonucleic acid (DNA).

SummaryContrary to data reported by Savitsky in rabbits, intravenous administration of heterologous DNA to rats causes no change in serum cholesterol concentration; nor did DNA alter the increase in cholesterol values seen in rats receiving a hypercholesterolemic diet.

A PROPOSED MECHANISM FOR THE EFFECT OF DIFFERENT DIETARY FATS ON SOME ASPECTS OF CHOLESTEROL METABOLISM

To explain the effect of dietary cholesterol and different fats on serum cholesterol concentration a hypothesis is proposed according to which the condition for the absorption of dietary cholesterol is its state of solution in dietary or endogenous fats. Dietary fats, free from cholesterol, exert their effect on serum cholesterol concentration by causing reabsorption of biliary or endogenous cholesterol. To test this hypothesis the solubility of cholesterol in a number of natural and modified triglyceride fats at 37 °C was determined and found to correlate with the effects of these fats on the serum cholesterol concentration of rats and man. Relatively high solubilities were associated with high serum levels and vice versa. Artificial modification of both unsaponifiable matter and fatty acids of triglyceride oils was found to alter the solubility of cholesterol in these oils. The solubility concept is discussed as a possible mechanism underlying the effect of different dietary fats on serum cholesterol concentration and other aspects of cholesterol metabolism such as absorption, excretion, and liver synthesis.

THE EFFECT OF DIETARY LIPIDS ON THE SERUM CHOLESTEROL OF RATS

Experimental conditions were devised under which the effect of dietary triglyceride oils on the serum cholesterol concentration of rats resembled the effect of these oils on man. No artificial additives were used in the diet. By the use of this technique, the hypocholesterolemic activity of sunflower seed oil was studied. The feeding of fractions prepared by chemical and physical means showed that the unsaponifiable matter was responsible for a substantial part of the hypocholesterolemic action of the unmodified oil. Several fractions with similar fatty acid compositions were prepared which had different effects on the serum cholesterol level. Some known compounds of the unsaponifiable matter were next fed, dissolved in coconut oil. β-Sitosterol and squalene had little effect but a combination of these with α-tocopherol and β-carotene produced a significant depressing effect. The administration of cholesterol with a fat-free diet did not raise the serum cholesterol level unless the sterol was given dissolved in oil. Increasing quantities of sterol of up to 6%, dissolved in oil, produced increasing serum levels. Larger quantities caused no further rise. The possibility that only dissolved cholesterol is absorbed is discussed.

A PROPOSED MECHANISM FOR THE EFFECT OF DIFFERENT DIETARY FATS ON SOME ASPECTS OF CHOLESTEROL METABOLISM

To explain the effect of dietary cholesterol and different fats on serum cholesterol concentration a hypothesis is proposed according to which the condition for the absorption of dietary cholesterol is its state of solution in dietary or endogenous fats. Dietary fats, free from cholesterol, exert their effect on serum cholesterol concentration by causing reabsorption of biliary or endogenous cholesterol. To test this hypothesis the solubility of cholesterol in a number of natural and modified triglyceride fats at 37 °C was determined and found to correlate with the effects of these fats on the serum cholesterol concentration of rats and man. Relatively high solubilities were associated with high serum levels and vice versa. Artificial modification of both unsaponifiable matter and fatty acids of triglyceride oils was found to alter the solubility of cholesterol in these oils. The solubility concept is discussed as a possible mechanism underlying the effect of different dietary fats on serum cholesterol concentration and other aspects of cholesterol metabolism such as absorption, excretion, and liver synthesis.

THE EFFECT OF DIETARY LIPIDS ON THE SERUM CHOLESTEROL OF RATS

Experimental conditions were devised under which the effect of dietary triglyceride oils on the serum cholesterol concentration of rats resembled the effect of these oils on man. No artificial additives were used in the diet. By the use of this technique, the hypocholesterolemic activity of sunflower seed oil was studied. The feeding of fractions prepared by chemical and physical means showed that the unsaponifiable matter was responsible for a substantial part of the hypocholesterolemic action of the unmodified oil. Several fractions with similar fatty acid compositions were prepared which had different effects on the serum cholesterol level. Some known compounds of the unsaponifiable matter were next fed, dissolved in coconut oil. β-Sitosterol and squalene had little effect but a combination of these with α-tocopherol and β-carotene produced a significant depressing effect. The administration of cholesterol with a fat-free diet did not raise the serum cholesterol level unless the sterol was given dissolved in oil. Increasing quantities of sterol of up to 6%, dissolved in oil, produced increasing serum levels. Larger quantities caused no further rise. The possibility that only dissolved cholesterol is absorbed is discussed.

Diet and cholesterolemia: V. effects of sulfur-containing amino acids and protein

Interrelationships among the effects of dietary protein, sulfur-containing amino acids, and choline on the serum cholesterol concentration of the rat have been studied. Hypercholesterolemia was induced by feeding rats a diet containing cholesterol, cholic acid, and saturated fat. When the diet contained choline, additional casein alleviated the hypercholesterolemia. A similar effect was obtained with a supplement of methionine equal to the amount in the casein. Cystine and cysteine, but not taurine, were as effective as methionine. These and other observations suggest that the serum cholesterol-lowering effect of protein supplements is due largely to the sulfur-containing amino acids they provide. The omission of choline from the diet also alleviated the hypercholesterolemia; but when the choline-free diet was supplemented with either choline or methionine, serum cholesterol concentration increased. A supplement of choline alone caused a much greater rise than a supplement of methionine or combined supplementation with choline and methionine. Thus methionine appears to have two opposing effects on serum cholesterol concentration in rats fed a hypercholesterolemic diet lacking choline: (a) a cholesterol-elevating effect attributable to its ability to spare choline by providing a supply of preformed methyl groups, and (b) a cholesterol-lowering effect common to sulfur-containing amino acids and not, dependent upon the provision of methyl groups.