Effect of Dietary Composition on Lipids in Serum and in Liver of Rats Fed a Cystine-excess Diet

The effects of dietary composition on lipids in serum and in liver of rats fed with a cystine- excess diet were investigated.

When starch was used as the carbohydrate source, the addition of excess-cystine caused an increase in serum cholesterol and phospholipids, and hepatomegaly. Phospholipids in serum of rats fed with a cystine-excess diet containing 5% corn oil were higher than those with a cystine-excess diet that was low in corn oil (0.1 %). The addition of konjac mannan and pectin prevented hypercholesterolemia, and the rise in phospholipids in serum was prevented by the addition of konjac mannan.

Liver cholesterol (mg/liver/100 g of body wt.) increased in rats fed with a cystine-excess diet.

The addition of excess cystine to a diet containing sucrose as the carbohydrate source resulted in a marked increase of cholesterol in serum and liver, and a decrease of serum triglycerides.

The replacement of starch by sucrose in the cystine-excess diet increased liver cholesterol.

Lipids, cholesterol, phospholipids and triglycerides in the liver, but not phospholipids, when expressed as mg per g of liver for rats fed with the diets containing sucrose, increased when compared to those for rats fed with the diets containing starch. In contrast, serum triglycerides increased.     

Kinetics of taurine depletion and repletion in plasma, serum, whole blood and skeletal muscle in cats

The relationship between taurine concentrations of plasma, whole blood, serum and skeletal muscle during taurine depletion and repletion was investigated in cats, to identify the most useful indicators of taurine status. Sixteen cats were fed a purified diet containing either 0 or 0.15 g/kg taurine for 5 months. Treatments were then reversed and the taurine concentration was measured during repletion and depletion phases. Plasma taurine exhibited the fastest rate (slow component) of depletion (t 1/2 = 4.8 wk), followed by serum (5.3 wk), whole blood (6.2 wk), and skeletal muscle (11.2 wk). Whole blood taurine was the first to replete at a rate of 0.74 wk to 1/2 maximal repletion, followed by serum (2.1 wk), skeletal muscle (3.5 wk), and plasma (3.5 wk). Whole blood more closely reflected skeletal muscle taurine concentrations than plasma during depletion, while plasma taurine concentrations appear to be the most valuable predictor of skeletal muscle taurine concentrations during repletion. This study suggests that the best clinical method to evaluate the taurine status of the cat is the determination and interpretation of both plasma and whole blood taurine concentrations.     

Liver Nonprotein Sulfhydryl and Taurine Concentrations,and Fat Content of Rats Fed a Low Protein Diet Supplemented with Sulfur-containing Amino Acids

The relative excess of some catabolites of sulfur-containing amino acids in the liver of rats fed a low protein diet might be one of the factors which cause the liver fat accumulation. To investigate the possibility were studied relationships between changes in concentrations of some metabolites of sulfur-containing amino acids and those in fat contents of rats fed a low protein diet consisting of heated soybean flour, casein or wheat flour with or without added methionine, threonine or lysine. The addition of 0.6% methionine to the 25% heated soybean flour diet increased the nonprotein-sulfhydryl (NP–SH) concentration and fat content in the liver. These changes were prevented by the further addition of 0.5% threonine to the diet, although the NP–SH concentration was remarkably higher than that of rats fed the unsupplemented diet. The addition of 0.6% cystine HC1 to the 25% heated soybean flour diet containing sufficient choline elevated the NP–SH concentration and fat content in the liver, which were not affected by the further addition of 0.5% threonine. The addition of 0.6% cystine HC1 to the 10% casein diet significantly increased the fat content, and NP–SH and taurine concentrations in the liver. The further addition of 0.5 % threonine completely decreased the fat content, and partially reduced the NP–SH and taurine concentrations. Effects of supplementation of 0.4% lysine HC1 to the 70% wheat flour diet on the fat content and NP–SH concentration in the liver demonstrated the trends similar to those of supplementation of cystine to the 10% casein diet. The further addition of threonine remarkably decreased the fat content, NP–SH and taurine concentrations in the liver.     

Dose-dependent effects of dietary gamma-linolenic acid on rat spleen lymphocyte functions.

Feeding rodents a diet rich in evening primrose oil (EPO), which contains 5-10 g gamma-linolenic acid (GLA)/100 g total fatty acids, has been shown to decrease lymphocyte proliferation and natural killer cell activity. However, EPO contains a very high level of linoleic acid which itself can affect lymphocyte functions and it is not clear to what extent the effects of EPO can be attributed to GLA. The current study investigated the effect of two levels of GLA in the rat diet upon immune cell functions; the level of linoleic acid was maintained below 30 g/100 g total fatty acids. Weanling rats were fed on high fat (178 g/kg) diets which contained 4.4 g or 10 g GLA/100 g total fatty acids in place of a proportion of linoleic acid. The total polyunsaturated fatty acid content and the n-6 to n-3 polyunsaturated fatty acid ratio of the diet were maintained at 35 g/100 g total fatty acids and 7, respectively. The fatty acid compositions of the serum and of spleen leukocytes were markedly influenced by that of the diet, with an increase in the proportions of GLA and dihomo-gamma-linolenic acid when the diets containing GLA were fed; these diets also increased the proportion of arachidonic acid in spleen leukocytes. Spleen lymphocyte proliferation in response to concanavalin A was significantly reduced (by 60%) by feeding the diet containing the higher level of GLA, but not by the diet containing the lower level of GLA. Spleen natural killer cell activity and prostaglandin E (PGE) production by spleen leukocytes were not significantly affected by inclusion of GLA in the diet, although there was a tendency towards decreased natural killer cell activity by cells from rats fed the high GLA diet. Thus, this study shows that dietary GLA is capable of altering the fatty acid composition of cells of the immune system and of exerting some immunomodulatory effects, but that the level of GLA in the diet must exceed 4.4 g/100 g total fatty acids for these effects to become apparent.     

Increase of bile acids synthesis and excretion caused by taurine administration prevents the ovariectomy-induced increase in cholesterol concentrations in the serum low-density lipoprotein fraction of Wistar rats

We examined the effect of dietary taurine on the concentrations of serum cholesterol and apolipoprotein in lipoprotein fractions of Six-month-old ovariectomized, which were used as a model of hypercholesterolemia in postmenopausal woman, or sham operated rats. Taurine significantly reduced the serum total and low-density lipoprotein cholesterol concentrations only in the ovariectomized rats. In contrast, taurine significantly lowered the serum apolipoprotein B concentration and serum very low-density lipoprotein-apolipoprotein E concentration only in the sham operated rats. The serum total and high density lipoprotein-apolipoprotein E concentrations were significantly lower in the rats fed taurine than in those fed the control diet regardless of whether they had undergone ovariectomy. The esterified cholesterol level in the liver was significantly lower and the level of hepatic cholesterol 7 alpha-hydroxylase activity was significantly higher in the rats fed taurine than in those fed the control diet. The total bile acids concentration in the feces and intestinal contents of rats fed taurine were significantly higher than those in rats fed the control diet regardless of whether they had undergone ovariectomy. In the sham-rats, taurine accelerated bile acid synthesis and excretion, thereby increasing cholesterol consumption. The increased cholesterol consumption might be compensated by accelerating cholesterol synthesis and/or reducing the synthesis and release of very low-density lipoprotein from the liver. But in the ovariectomized rats, although taurine also accelerated bile acid synthesis and excretion, cholesterol demand might be compensated by excess cholesterol in the blood.     

Effect of taurine on cholesterol metabolism in hamsters: up-regulation of low density lipoprotein (LDL) receptor by taurine

The effects of taurine on hepatic cholesterol metabolism were investigated in hamsters fed a high-fat diet or normal chow. Two weeks-treatment of taurine at 1% in drinking water prevented high-fat diet-induced increase in cholesterol levels of serum and liver. The decrease in serum cholesterol by taurine was due to decrease in non-HDL cholesterols. A similar tendency was noted in serum and liver cholesterol levels of hamsters fed a normal diet. In hamsters fed a high-fat diet, taurine prevented elevation in hepatic activity of acyl-CoA:cholesterol acyltransferase (ACAT) and increased the activity of cholesterol 7alpha-hydroxylase. Taurine also increased cholesterol 7alpha-hydroxylase activity in hamsters fed normal chow. Studies on liver membranes revealed that taurine increased 125I-labeled LDL binding by 52% and 58% in hamsters fed either a normal chow or high-fat diet, respectively. Furthermore, LDL kinetic analysis showed that taurine intake resulted in significant faster plasma LDL fractional catabolic rates (FCR). These results suggest that taurine elevates hepatic LDL receptor and thereby decreases serum cholesterol levels, an event which may be the result of hepatic cholesterol depletion as a consequence of increased bile acid synthesis via enhancement of cholesterol 7alpha-hydroxylase activity. Thus, up-regulation of the LDL receptor and subsequent increase in receptor- mediated LDL turnover may be a key event in the cholesterol-lowering effects of taurine in hamsters.     

Improving effect of dietary taurine supplementation on the oxidative stress and lipid levels in the plasma,liver and aorta of rabbits fed on a high-cholesterol diet

The effect of a high-cholesterol diet with or without taurine on lipids and oxidative stress in the plasma, liver and aorta of rabbits was investigated. The animals were maintained on a basal diet (control), a high-cholesterol diet (HC, 1% w/w), or a high- cholesterol diet supplemented with taurine (HCHT, 2.5% w/w) for two months. Taurine has an ameliorating effect on atherosclerosis together with a decreasing effect on the cholesterol and triglyceride levels in rabbits fed on an HC diet. The HCHT diet caused a significant decrease in the malondialdehyde (MDA) and diene conjugate (DC) levels in the plasma, liver and aorta of rabbits as compared to the HC group. This treatment did not alter the antioxidant system in the liver of rabbits in the HC group. Our findings indicate that taurine ameliorated oxidative stress and cholesterol accumulation in the aorta of rabbits fed on the HC diet and that this effect may be related to its antioxidative potential as well as its reducing effect on serum lipids.     

Hypolipidemic action of taurine in rats.

The effect of taurine on the serum and liver cholesterol and triglyceride levels was studied in rats fed cholesterol plus cholic acid. Four groups of 4 weeks old rats were fed control diet, hypercholesterolemic diet (HCD), HCD + 1% taurine or HCD + 2% taurine for 8 weeks. Addition of taurine in HCD diet showed a significant reduction not only in serum total cholesterol and triglyceride levels but also in liver total cholesterol, lipid and triglyceride contents compared to the animals fed HCD alone. Histological examination of organs of these animals showed severe fatty vacuolation in livers and signet ring type vacuolation in kidneys of rats fed HCD. Taurine showed ameliorating effect on these abnormalities. The animals fed taurine in HCD also showed increased bile and sterol excretion in faeces compared to rats fed HCD alone. Taurine showed significant hypocholesterolemia in rats probably by enhancing the catabolism of cholesterol and reducing the absorption of dietary cholesterol.     

Effect of allicin from garlic powder on serum lipids and blood pressure in rats fed with a high cholesterol diet

The use of fresh aqueous garlic extract is known to be effective in reducing thromboxane formation by platelets in both in vivo and in vitro animal models of thrombosis. In the present study, we studied the effect of Lichtwer garlic powder (containing 1.3% alliin equivalent to 0.6% allicin) on the serum cholesterol, triglyceride, glucose, protein, and systolic blood pressure in rats fed with a high cholesterol diet. Experimental rats were fed a 2% high cholesterol diet with and without garlic powder for 6 weeks. Control rats were fed a normal diet. The aqueous garlic powder extract was given orally to rats on a daily basis. It was observed that cholesterol-fed animals had a significant increase in serum cholesterol compared to the control group of rats fed on a normal diet. However, when the rats were fed with a high cholesterol diet mixed with garlic powder, there was a significant reduction in their serum cholesterol levels compared with the group which were on a diet containing high cholesterol without garlic powder. Serum triglyceride levels were also significantly lowered by garlic powder when compared to control and high cholesterol diet group rats. The blood pressure of the high cholesterol diet animals was significantly higher compared to the animals receiving the control diet. The blood pressure of the animals receiving garlic powder and high cholesterol diet was significantly lower as compared to the high cholesterol and control diet group. No significant changes were observed in the serum glucose and protein in all of the rats. These results show that garlic is beneficial in reducing blood cholesterol, triglycerides levels and systolic blood pressure in hypercholesterolemic rats. Our experimental results show that garlic may beneficially affect two risk factors for atherosclerosis--hyperlipidemia and hypertension.     

Prevention of hypercholesterolemia and atherosclerosis in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail by taurine supplementation

The effects of taurine supplementation on the serum cholesterol levels and the progression of atherosclerosis were investigated in the hyperlipidemia- and atherosclerosis-prone Japanese (LAP) quail. The ingestion of a high-cholesterol diet containing 1% cholesterol by LAP quails for 60 days resulted in a marked elevation in serum non-HDL cholesterol and triglyceride, as well as severe aortic lesions with lipid droplets. An immunohistochemical study showed that the lesion consisted of mainly lipid-rich macrophages and T cells. Sixty-day taurine supplementation (1% in drinking tap water) to LAP quails fed high-cholesterol diet containing 1% cholesterol significantly reduced serum non-HDL cholesterol from 4,549 to 2,350 mg/dl. The serum triglyceride level also decreased after taurine supplementation from 703 to 392 mg/dl. Although the HDL cholesterol level significantly decreased due to the high-cholesterol diet, it recovered to the control level fed a regular diet in response to taurine. Bile acid production was stimulated and hepatic cholesterol was reduced by taurine supplementation. A quantitative analysis using aortic cross-sections showed that areas of oil-red O positive lipid accumulation significantly decreased by 74% after taurine supplementation. These results demonstrated the lipid-lowering and anti-atherosclerotic effects of taurine in a diet-induced hyperlipidemic LAP quail model. The prevention of atherosclerosis by taurine is mainly attributed to an improvement in the serum cholesterol and triglyceride levels, which may be related to changes in the hepatic cholesterol metabolism.     

Antiatherogenic effect of taurine in high fat diet fed rats

The role of taurine on atherogenesis induced by high fat diet in rats, a species which depends entirely on taurine for conjugation of bile acids has been investigated. Wistar male rats were fed on (p.o.) taurine in addition to high fat diet (11% coconut oil w/w) for 6 months. High fat diet caused significant increase of serum total cholesterol (2 fold), serum triglycerides (92.6%), LDL cholesterol (92.3%) and body weight gain (2.8 fold). Taurine administration significantly reduced serum cholesterol (37%), triglycerides (94.5%), LDL cholesterol (34%), body weight (46%). It also significantly reduced aortic cholesterol and thiobarbituric acid reactive substances and there was a significant increase of reduced glutathione. Taurine significantly increased fecal bile acids which may have resulted in significant decrease of serum cholesterol. Aortic lesion index was significantly decreased in the taurine administered group suggesting the antiatherogenic effect of taurine. It is concluded that taurine attenuated the atherogenesis possibly by its hypocholesterolemic and antioxidant property.     

Immunomodulatory effects of ovine serum immunoglobulin in the growing rat

This study aimed to determine whether orally administered ovine serum immunoglobulin (Ig) modulates aspects of immunity such as phagocytosis, lymphocyte proliferation, cytokine production, intestinal and plasma Ig concentrations in growing rats. Forty-five male Sprague-Dawley rats (n = 15/group) were used in the 21-day study, and fed a basal control diet (BD; no Ig) or two test diets: freeze-dried ovine Ig (FDOI) and inactivated ovine Ig (IOI). Phagocytic activity of peripheral blood leukocytes and lymphocyte proliferation in the presence of the mitogen concanavalin A (ConA) was greater (P < 0.05) for the FDOI-fed rats than for the BD- and IOI-fed groups. ConA-stimulated and unstimulated spleen cell culture produced higher (P < 0.05) interferon-γ and interleukin-4, respectively, from rats fed the FDOI than rats fed the BD diet. In the jejunum, ileum and plasma, rats fed FDOI produced higher (P < 0.05) concentrations of secretory IgA (sIgA) than rats fed IOI or BD. Rats fed the FDOI diet had greater jejunal (P = 0.037) and lower plasma (P = 0.025) rat IgG concentrations than rats fed either BD or IOI. In conclusion, an ovine Ig fraction selectively modulated various indices of immune function.     

Effects of dietary chromium chloride supplementation on performance,some serum parameters,and immune response in broilers

This study was conducted to investigate the effect of increasing dietary levels of inorganic chromium (CrCl₃·6H₂O) on the performance, blood chemistry, and immune response of broilers. Eighty newly hatched Ross PM3 broiler chicks were evenly distributed to five groups of 16 chicks each. Two groups (control and only sheep red blood cell inoculated) were fed the basal diet containing 2.2 and 4.5 mg Cr/kg and the remaining groups were fed 20, 40, or 80 mg/kg Cr-supplemented diets for 44 d. Chicks in all groups, except in the control, at 3 and 5 wk of age, were injected intraperitonally with sheep red blood cell for determining the primary and secondary antibody responses, respectively. When the chicks were 4 wk of age, a delayed-type hypersensitivity test was performed. White blood cells were differentiated. Blood samples were collected for the determination of serum proteins, glucose, cholesterol, cortisol, minerals, and alkaline phosphatase activity and for antibody response. Chromium had no effect on weight gain, but 20 mg/kg supplemental Cr resulted in 18.57% reduction in feed consumption and improved feed efficiency by 16.77%. Chromium did not affect serum cholesterol and P levels but reduced serum glucose and increased serum protein, Cr, Ca, and Mg levels, and ALP activity. A slight reduction was observed with Cr supplementation in cortisol levels. Slight but not significant increases were observed with Cr in serum Zn and Cu. Chromium increased the ratio of bursa of Fabricius and liver to body weight. Heterophil and monocyte counts and heterophil/lymphocyte ratio were reduced and lymphocyte counts, total antibody, IgG, and IgM titers were increased by supplemental Cr. All levels of Cr increased the cell-mediated response to phytohemagglutinin. No alterations in tissues were observed by histopathological examinations.     

The effect of taurine on cholesterol degradation in mice fed a high-cholesterol diet

The hypocholesterolemic effect of taurine was examined in mice fed a high-cholesterol diet containing 1% cholesterol and 0.25% sodium cholate. Male C57BL/6 mice were divided into 3 groups: control group (HC), 1% taurine-supplemented group (HCT+), and taurine-deficient group (HCT-) produced by supplying 0.5% guanidinoethyl sulfonate (GES) solution ad libitum instead of water. After they were fed with the respective diet or drinking water for 4 weeks, the liver taurine level was reduced 80% in the HCT- group compared with that in the HC group, although there was no difference in the serum taurine amount between the two groups. The formation ratio of cholesterol gallstones increased from 71% to 100% by taurine deficiency, and decreased to 0% by taurine supplementation. Compared with the HC group, serum and liver cholesterol significantly decreased, and the excretion of fecal bile acid notably rose in the HCT+ group but tended to lower in the HCT- group. There were no differences in LDL receptor protein level among the three groups. In the subsequent experiment, triglycerides (TG) secretion rate was determined and found to be significantly suppressed by taurine supplementation. In conclusion, it is suggested that taurine does not up-regulate LDL receptor protein level, and the decrease in cholesterol in the circulation is mainly due to its suppressive effect on TG secretion from the liver.     

Influence of casein and soy flour proteins on aminoacid content in the liver of experimental animals.

We have observed a significantly increased content of fats and decreased content of proteins in the liver of experimental rats fed a diet supplemented with 25% casein proteins in comparison with the application of de-fatted soy flour. Casein proteins have a higher content of methionine in relation to cystine than baked soy flour. But the soy diet in contrast to the casein diet has a high content of free aminoacids which are not present in casein at all: aspartic acid, asparagine, alpha-aminoadipic acid, methionine, norleucine, lysine, phenylalanine, beta-alanine, ethanolamine, histidine, proline, gamma-aminobutyric acid, taurine. Differences in free valine, alanine, arginine, glycine, ornithine and cysteic acid are also significant. The content of free aminoacids in the liver of experimental animals fed a soy diet is high in the content of cystine, cystathionine, ornithine, beta-aminoisobutyric acid, beta-alanine, gamma-aminobutyric acid, leucine. We have also found accumulation of methionine, glycine, alpha-aminobutyric acid, taurine and citrulline in free aminoacids from the liver of animals fed a casein diet. Citrulline and glycine in free aminoacids from the liver of animals fed a soy protein supplement were not recorded. Our investigations have shown that the application of a soy diet enriched with cystine acts protectively on methionine and that methionine is preferentially utilized for protein synthesis. The catabolic pathway of methionine prevails in animals on a casein diet.     

Improvement in cholesterol metabolism in mice given chronic treatment of taurine and fed a high-fat diet

The effects of chronic treatment of taurine on hypercholesterolemia and atherosclerosis were examined in C57BL/6J mice fed a high-fat diet containing 15% fat and 1.25% cholesterol. Taurine was dissolved in drinking water at 1% (w/v) and was given to mice ad libitum during 6 months-feeding of a high-fat diet. Hypercholesterolemia occurred and lipid accumulation on the aortic valve was evident. Taurine treatment lowered serum LDL + VLDL cholesterol by 44% in mice fed a high-fat diet, while it elevated serum HDL cholesterol by 25%. As a result, the atherogenic index, the ratio of HDL to LDL + VLDL was markedly improved. Cholesterol content in the liver also decreased by 19% with taurine. Similar tendencies were seen in mice fed regular chow, but the changes were not significant. The area of aortic lipid accumulation, which served as an index of atherosclerosis, was reduced by 20% with taurine. In the liver, taurine doubled the activity of cholesterol 7alpha-hydroxylase. These observations, together with prior findings, suggest that the cholesterol-lowering action of taurine may relate to the increased conversion of cholesterol to bile acids via stimulation of cholesterol 7a-hydroxylase activity. Thus, chronic treatment of high-fat mice with taurine improves the abnormal profile of the serum lipoproteins, and thereby retards the progression of atherosclerosis.     

Food restriction-like effects of dehydroepiandrosterone: decreased lymphocyte numbers and functions with increased apoptosis.

Both dietary dehydroepiandrosterone (DHEA) and food restriction can prevent or modulate the initiation or progression of a number of diseases in rodents and prolong life span. We sought to determine if these interventions have common mechanisms of action in regulating lymphocyte functions and cell numbers. We observed that male C57BL/6 mice receiving DHEA in the diet (0.45%, w/w) ate approximately 50% as much food as mice on the DHEA-free diet, and this was reflected in decreased body weights throughout a 10-week period. Mice either fed the DHEA-containing diet or pair-fed to the DHEA-treated mice had decreased spleen and thymus weights and lymphocyte cell numbers compared to mice having free access to the control diet. Mice were fed these diets for 2 weeks before and 2 weeks after exposure to sublethal irradiation (500 cGy). In mice fed DHEA or pair-fed, there was a decrease in spleen cell numbers, and B cells were the most severely affected. The frequency of apoptosis in peripheral blood cells increased from <5% in nonirradiated controls to >50% within 4 days after starting DHEA or pair-feeding. Shortly after irradiation, >87% of blood lymphocytes were hypodiploid (apoptotic) in all groups. By 9 days only 27% of lymphocytes in mice on the control diet were hypodiploid compared to 62% in DHEA and 74% in pair-fed mice. In addition, both DHEA and pair-fed mice had significant reductions in T-cell function (contact hypersensitivity to dinitrofluorobenzene), B cell function (antibody response to trinitrophenolated-lipopolysaccharide), and NK cell function (lung clearance of radiolabeled YAC-1 tumor cells) 2 weeks after irradiation. In a complementary study, peripheral blood lymphocytes from na?ve mice were treated overnight with various concentrations of either DHEA or hydrocortisone 21-acetate. Only glucocorticoid-treated cells underwent apoptosis. Thus, DHEA induces apoptosis in vivo but not in vitro. We conclude that dietary DHEA induces apoptosis and decreased lymphocyte production and function in C57BL/6 mice largely by reducing food intake.     

Effects of an alpha-glucosidase inhibitor, acarbose, on blood glucose and serum lipids in streptozotocin-induced diabetic rats

Effects of either a single dose or a long-term administration of an alpha-glucosidase inhibitor, acarbose, on blood glucose, cholesterol concentrations in serum lipoprotein fractions, triglycerides and free fatty acids were examined in streptozotocin-induced diabetic rats. In experiment 1, starch loading tests were performed with or without adding acarbose. The addition of acarbose (0.75 mg per kg of body weight or over) significantly reduced the elevation of blood glucose levels. In experiment 2, the animals were divided into three groups: Group A fed on a control diet, Group B fed on a diet containing 5 mg acarbose in 100 g of diet and Group C fed on a diet containing 20 mg acarbose in 100 g of diet. The food intake in Group C was significantly reduced by 22% as compared to Group A, while the food intake in Group B showed no change. The high dose of acarbose showed a tendency to lower fasting blood glucose levels, but the difference was statistically insignificant. However, postprandial glucose levels in Group C at each period examined and in Group B at 30 days were significantly lower than the counterparts in Group A. Acarbose caused a dose-dependent decrease in serum total cholesterol levels and HDL-cholesterol: total cholesterol ratios were elevated in Group B and C. Serum triglyceride levels in Group B and C were extremely lower than those in Group A on and after 20 days. These results indicate that the addition of acarbose to the diet induces a decrease in postprandial blood glucose levels and simultaneously causes an improvement in lipid metabolism of streptozotocin-induced diabetic rats.     

大豆异黄酮对电离辐射小鼠淋巴细胞的防护作用

目的研究大豆异黄酮(SI)对小鼠淋巴细胞的辐射防护作用。方法24只雄性昆明小鼠,随机分为正常对照组、辐射对照组和辐射补充0.5%SI组,喂养2周后,4.0Gy照射。照射后24 h处死小鼠,取血、胸腺和脾脏分离淋巴细胞,进行血淋巴细胞计数、观察DNA损伤情况;培养胸腺和脾脏淋巴细胞,检测3H-dT掺入量,观察淋巴细胞的增殖能力,计算淋巴细胞的增殖指数。结果辐射使小鼠胸腺和脾脏淋巴细胞数明显减少、胸腺淋巴细胞增殖能力和脾脏淋巴细胞转化指数降低、血淋巴细胞DNA损伤增加,这些变化均具有统计学意义;补充SI可降低胸腺和脾脏淋巴细胞数的减少幅度,降低胸腺淋巴细胞增殖能力和脾脏淋巴细胞转化指数下降幅度,减少辐射对血淋巴细胞DNA损伤程度,其中SI对胸腺淋巴细胞增殖能力和对血淋巴细胞DNA损伤程度的防护作用与辐射对照组相比有统计学意义。结论大豆异黄酮可对小鼠的血、胸腺和脾脏淋巴细胞有一定的辐射防护作用。     

Effects of Sulfur-containing Amino Acids and Glycine on Plasma Cholesterol Level in Rats Fed on a High Cholesterol Diet

The effects of the addition of individual amino acids on methionine-induced hypercholesterolemia (experiment 1), and the interacting effects of dietary protein level and sulfur-containing amino acids and glycine on plasma cholesterol concentration (experiment 2) were studied in growing rats fed on a high cholesterol diet. In experiment 1, rats were fed on a 25% casein-0.75% methionine (25CM) diet containing 2.5% of individual amino acids for 2 weeks. Methionine-induced hypercholesterolemia was prevented by the concurrent addition of glycine or serine, but the other amino acids tested (alanine, threonine, leucine, phenylalanine, lysine, arginine, and glutamic acid) had no effect. Histidine rather enhanced the hypercholesterolemia. In experiment 2, rats were fed on a 10%, 25%, or 50% casein diet containing 0.75% methionine, 0.60% cystine, 0.63% taurine, 2.5% glycine, or 0.75% methionine +2.5% glycine for 3 weeks. Dietary addition of 0.75% methionine increased the plasma cholesterol concentration for the 25% and 50% casein diets, but it decreased the plasma cholesterol for the 10% casein diet. When the addition level of methionine was doubled in the 10% casein diet, the plasma cholesterol concentration was significantly higher for the 1.5% methionine-added diet than for the 0.75% methionine-added diet. Cystine and taurine lowered plasma cholesterol for all dietary casein levels. Methionine-induced hypercholesterolemia with 25% and 50% casein diets was prevented by the glycine supplementation. These data suggest that sulfur-containing amino acids and glycine are important in plasma cholesterol regulation.