Beneficial effects of natural Jeju groundwaters on lipid metabolism in high-fat diet-induced hyperlipidemic rats

BACKGROUND

Groundwater is believed to possess many beneficial effects due to its natural source of various minerals. In this study, we examined the effects of natural Jeju groundwater S1 (Samdasoo™), S2 and S3 pumped up from different locations of Jeju Island, Korea, along with local tap water, on body weight gain, serum lipids and lipoproteins, and liver histopathology in high-fat diet-induced hyperlipidemic rats.

MATERIALS/METHODS

Rats were randomly and equally divided into 6 groups. Different water samples were supplied to the hyperlipidemic rats as their daily drinking water and the widely-used anti-hyperlipidemic drug simvastatin was used as a positive control. Body weight, serum lipids and lipoproteins were measured weekly. Liver weight, liver index and liver histopathology were examined after the execution of the rats.

RESULTS

After drinking Jeju groundwaters for two months, S2 but not S3 significantly reduced weight growth and serum triglycerides levels and increased high density lipoprotein-C (HDL-C) without affecting total cholesterol or LDL-C. S1 and particularly S2 significantly reduced the severity of liver hypertrophy and steatosis. All Groundwaters had much higher contents of vanadium (S3>S2>S1>>tap water) whereas S1 and S2 but not S3 markedly blocked autoxidation of ferrous ions.

CONCLUSION

Jeju Groundwater S1 and particularly S2 exhibit protective effects against hyperlipidemia and fatty liver and hypothesize that the beneficial effect of Jeju Groundwaters may be contributed from blockade of autoxidation of ferrous ions rather than their high contents of vanadium.     

Cinnamate supplementation enhances hepatic lipid metabolism and antioxidant defense systems in high cholesterol-fed rats

This study investigated the effect of cinnamate, a phenolic compound found in cinnamon bark and other plant materials, on lipid metabolism and antioxidant enzyme activities in rats fed a high cholesterol diet. Three groups of rats were given a diet containing 1 g of cholesterol/kg for 6 weeks. The control group only received the high cholesterol diet, whereas the other two groups received a diet supplemented with lovastatin or cinnamate (0.1 g/100 g of diet). The plasma high-density lipoprotein-cholesterol levels were significantly higher in the cinnamate group than in either the control or lovastatin groups, and the atherogenic index was significantly lower in rats with cinnamate supplementation. Supplementation with cinnamate resulted in significantly lower hepatic cholesterol and triglyceride levels. Accumulation of hepatic lipid droplets was higher in the control group than in the rats supplemented with either cinnamate or lovastatin. Hepatic 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activity was significantly lower in the cinnamate group compared with the other groups, whereas only acyl-CoA:cholesterol acyltransferase activity was significantly lower in the lovastatin group compared with the control group. Cinnamate supplementation resulted in higher catalase and glutathione peroxidase activities, while hepatic thiobarbituric acid-reactive substances were significantly lower in both the cinnamate and lovastatin groups. The fecal acidic sterol was higher in the lovastatin group than in the control or cinnamate groups. These results suggest that dietary cinnamate inhibits hepatic HMG-CoA reductase activity, resulting in lower hepatic cholesterol content, and suppresses lipid peroxidation via enhancement of hepatic antioxidant enzyme activities.     

Influences of oyster or clam feeding on lipid metabolism in rats.

Rats were fed on three kinds of diets for two weeks: (I) basal diet, (II) containing 0.1% cholate and (III) containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups to whose diet was added 0, 5 or 10% (dry weight) of minced oyster (Callocorchina) or clam (Tapes japonica). The serum and liver cholesterol levels of the rats fed the basal diet were reduced by feeding oyster or clam. The serum and liver triglyceride levels of all dietary groups were lowered markedly by feeding oyster or clam. The activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the basal groups fed oyster or clam. These effects were observed in 5 and 10% shellfish feeding. These shellfish may be considered hypolipidemic foods.     

The effects of dietary fiber feeding on cholesterol metabolism in rats

The flux through the sterol biosynthetic pathway was studied in hepatocytes isolated from male Sprague-Dawley rats fed diets containing one of four fiber sources: cellulose, pectin, oat bran and wheat bran. Sterol synthesis measured by the incorporation of tritiated water or [2-14C]mevalonic acid was not inhibited in hepatocytes isolated from animals fed diets containing cellulose, pectin, oat bran or wheat bran when compared to animals fed a fiber-free diet. Based on these results, it is concluded that the intake of fiber has no inhibitory effect on endogenous sterol synthesis. In fact, in comparison to that in fiber-free controls, sterol synthesis was markedly elevated in pectin- and wheat bran-fed animals. In the case of the pectin-treated animals, the higher synthetic rate corresponded to an increase in 3-hydroxy-3-methylglutaryl coenzyme A reductase activity.     

半饥饿状态下高脂喂养对大鼠肉毒碱及脂类代谢的影响

目的探讨高脂饲料喂养半饥饿状态下大鼠肉碱及脂肪代谢的变化.方法用限食的方法造成半饥饿大鼠模型,观察给予普通饲料的半饥饿对照组与给予高脂饲料的实验组血浆肉碱浓度、附睾脂肪垫重量,肝游离氨基酸和脂肪含量,血中甘油三酯、游离脂肪酸以及游离氨基酸浓度等指标的变化.结果给予高脂饲料的实验组动物血浆游离肉碱浓度显著低于正常组和实验前水平(P＜0.05);肝脂肪含量、血游离脂肪酸浓度均显著高于半饥饿对照组(P＜0.05);两组半饥饿动物血和肝脏中大部分游离氨基酸浓度显著低于正常组,半饥饿对照组其浓度降低更显著,同时合成肉碱的赖氨酸和蛋氨酸浓度也显著降低.结论高脂饲料喂养半饥饿状态下,游离肉碱浓度降低,脂类代谢负担加重,提示在高脂半饥饿状态下需补充外源性肉碱.     

Beneficial effects of ginger (Zingiber officinale) on carbohydrate metabolism in streptozotocin-induced diabetic rats

Zingiber officinale (ZO), commonly known as ginger, has been traditionally used in the treatment of diabetes mellitus. Several studies have reported the hypoglycaemic properties of ginger in animal models. The present study evaluated the antihyperglycaemic effect of its aqueous extract administered orally (daily) in three different doses (100, 300, 500?mg/kg body weight) for a period of 30?d to streptozotocin (STZ)-induced diabetic rats. A dose-dependent antihyperglycaemic effect revealed a decrease of plasma glucose levels by 38 and 68?% on the 15th and 30th day, respectively, after the rats were given 500?mg/kg. The 500?mg/kg ZO significantly (P?相似文献   

Entire potato consumption improves lipid metabolism and antioxidant status in cholesterol-fed rat

Background Vegetables and fruits are rich sources of a variety of nutrients, including vitamins (E and C), trace minerals, and dietary fibers, and many other classes of biologically active compounds such as carotenoids and polyphenols, which are often assumed to protect against degenerative pathologies such as cardiovascular diseases. Although potato is considered as a starchy food, it is also included in the category of vegetables by its micronutrient content. Aim of the study In the present study, we investigated in the rat the effect of a potato-enriched diet on lipid metabolism and antioxidant protection. Results Feeding rats a potato-enriched diet for 3 weeks led to a significant decrease in cholesterol and triglyceride levels in plasma (respectively, −30%, P<0.0001 and −36%, P<0.05) and cholesterol level in liver (−42%, P<0.0001). Antioxidant status was also improved by potato consumption. TBARS levels in heart were decreased and vitamin E/triglycerides ratio in plasma was improved. Conclusions Our present results suggest that consumption of cooked potatoes (consumed with skin) may enhance antioxidant defense and improve the lipid metabolism. These effects could be interesting for prevention of cardiovascular disease.     

Favorable effects of egg white protein on lipid metabolism in rats and mice

Egg is a cholesterol-rich food and has a strong hyper-cholesterolemic action. However, all the cholesterol is in egg yolk and egg white is cholesterol-free. The effect of egg white protein and its hydrolysates on the serum lipids were compared with casein and soybean protein in rats and mice. The animals were given 30% casein diet (Ca group) or diets of 15% casein plus 15% soybean protein isolate (SPI group), egg white protein (EW group) or egg white protein hydrolysates (EW-P group) for 3 (rats) or 2 (mice) weeks. Food intake and growth were very similar among the different dietary groups. Hypocholesterolemic effect was observed in SP, EW and EW-P groups in rats and EW group in mice. Prevention of the reduction of HDL-cholesterol was found in EW and EW-P groups in rats and EW-P group in mice. The result suggests the possibility of the use of egg white for the prevention and treatment of hyper-cholesteremia.     

Amylomyces rouxii strain CBS 438.76 affects cholesterol metabolism in cholesterol-fed rats

We examined the effects of Amylomyces rouxii, which is a mold found in some fermented foods in Indonesia, on serum cholesterol and hepatic LDL receptor mRNA in rats. Rats were fed a 0.5% cholesterol-enriched diet with (A. rouxii group) or without (control group) 30 g/kg A. rouxii for 4 wk. There were no significant differences in the body weight, food intake or liver weight among the groups. However, the weight of the cecum in the A. rouxii-fed group was significantly higher than that in the control group. The cecal pH in the A. rouxii-fed group was significantly lower than that in the control group. Cecal acetic acid, propionic acid and total SCFA concentrations in the A. rouxii-fed group were significantly higher than those in the control group. The serum total cholesterol and VLDL+intermediate density lipoprotein (IDL)+LDL-cholesterol concentrations in the control group were significantly higher than those in the A. rouxii-fed group at the end of the 4-wk feeding period. There were no significant differences in the HDL-cholesterol or triglyceride concentrations between the groups. The hepatic LDL receptor and cholesterol 7alpha-hydroxylase mRNA levels in the A. rouxii-fed group were significantly higher than those in the control group. The results of this study demonstrate that feeding of A. rouxii lowers the serum total cholesterol level by enhancement of the cecal SCFA concentration and the hepatic LDL receptor mRNA.     

Erythrocyte lipid peroxidation, glutathione and vitamin E levels in cholesterol-fed rats

Erythrocyte cholesterol and phospholipid levels, the susceptibility of erythrocytes to lipid peroxidation as well as erythrocyte glutathione and vitamin E levels were determined in rats fed a high cholesterol (2%, w/w) and high cholic acid (0.5%, w/w) diet for 3 months. Cholesterol feeding caused an increase in erythrocyte cholesterol levels, but no change was observed in erythrocyte phospholipid levels. Dietary cholesterol did not alter the susceptibility of erythrocytes to lipid peroxidation as well as erythrocyte glutathione and vitamin E levels in rats.     

Effect of retinoic acid and retinyl acetate feeding upon lipid metabolism in adrenalectomized rats.

Many reports have appeared in the literature suggesting that vitamin A may exert some of its effects via changes in adrenocortical activity. A series of experiments were performed in order to assess the possible role of the adrenal gland in vitamin A-induced lipid alterations in rats. Adrenalectomized, sham-operated, and intact rats were fed retinoic acid or retinyl acetate at several levels. Either 25 or 100 retinol equivalents (RE)/g dry diet were fed to male Sprague-Dawley rats for periods of 7 or 28 days. Neither compound had an effect on the concentration of liver glycerides, phospholipids, cholesterol, or total lipids. Vitamin A, especially in the form of retinoic acid, was found to induce an elevation of plasma triglycerides. The presence of the adrenal gland was not necessary for the induction of hypertriglyceridemia nor was there any indication of increased adrenocortical output (as measured by plasma corticosterone level) as a result of vitamin A feeding. There was a reduction in circulating retinol as a result of retinoic acid feeding at either 25 or 100 RE in sham-operated and adrenalectomized rats but not in unoperated rats. These experiments demonstrate that vitamin A, especially in the form of retinoic acid, fed at as low as 25 RE/g diet to the rat can induce hypertriglyceridemia, and that the adrenal gland does not mediate this effect.     

Metabolic effects of coconut, safflower, or menhaden oil feeding in lean and obese Zucker rats.

The aim of the present investigation was to study the effects of fish oil feeding in obese Zucker rats to establish its suitability as an animal model of hyperlipidaemia, and to understand the possible mechanism of fish oil-induced perturbations in cell metabolism. Lean and obese Zucker rats were fed on diets containing 180 g coconut, safflower, or menhaden oil/kg for 10 weeks. Body-weights and food intakes of lean coconut (LC), safflower (LS), and menhaden (LM) groups were similar. Obese menhaden (OM) rats had lower food intakes and body-weights compared with obese coconut (OC) and obese safflower (OS) groups, but values for all obese rats were higher than those for lean rats. Liver weights were higher in obese compared with lean rats, but on a percentage body-weight basis menhaden oil rats had higher values within genotype. Serum cholesterol and triacylglycerol levels were lower in the OM group compared with the OC and OS groups, and in the LM group compared with the LC group. Glucose and insulin levels were highest in OS rats followed by OC and OM rats and then the lean rats. Serum triiodothyronine and thyroxine were lower in OM rats compared with OC and OS rats. Liver mitochondrial state 3 rates with glutamate-malate and succinate were lower; mitochondrial beta-oxidation was unaffected and peroxisomal beta-oxidation was higher in menhaden oil rats compared with both coconut and safflower oil rats. In general, consumption of menhaden oil lowered hepatic malic enzyme (EC 1.1.1.38, 1.1.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glutathione peroxidase (EC 1.11.1.9) activities and elevated long-chain fatty acyl-CoA hydrolase (EC 3.1.2.2) activity when compared with the two other diets. It is concluded that obese Zucker rats do respond like human subjects to fish oil feeding but not to vegetable oils. The hypolipidaemic effect of fish oil appears to be mediated through a lowering of lipogenic enzymes, glucose-6-phosphate dehydrogenase and malic enzyme.     

Effect of dietary protamine on lipid metabolism in rats

Protamine has been widely used as a pharmaceutical product and natural food preservative. However, few studies have been conducted to assess the beneficial function of dietary protamine. This study examined the effects of dietary salmon protamine on serum and liver lipid levels and the expression levels of genes encoding proteins involved in lipid homeostasis in the liver of rats. Groups of male Wistar rats were fed AIN93G diet containing 2% or 5% protamine. After 4 weeks of feeding these diets, markedly decreased serum and liver cholesterol (CHOL) and triacylglycerol levels were noted. Increased activity of liver carnitine palmitoyltransferase-2 and acyl-CoA oxidase, which are key enzymes of fatty acid β-oxidation in the mitochondria and peroxisomes, was found in rats fed on protamine. Furthermore, rats fed protamine showed enhanced fecal excretion of CHOL and bile acid and increased liver mRNA expression levels of ATP-binding cassette (ABC) G5 and ABCG8, which form heterodimers and play a major role in the secretion of CHOL into bile. The decrease in triacylglycerol levels in protamine-fed rats was due to the enhancement of liver β-oxidation. Furthermore, rats fed protamine exhibited decreased CHOL levels through the suppression of CHOL and bile acid absorption and the enhancement of CHOL secretion into bile. These results suggest that dietary protamine has beneficial effects that may aid in the prevention of lifestyle-related diseases such as hyperlipidemia and atherosclerosis.     

Interactive effect of hesperidin and vitamin E supplements on cholesterol metabolism in high cholesterol-fed rats

Certain bioflavonoids are potent antioxidants and have pharmacologic effects similar to those of vitamin E. Accordingly, the interactive effect of hesperidin and vitamin E was studied with respect to cholesterol metabolism and the antioxidant status. Hesperidin supplement (0.1%, wt/wt) with comparable levels of vitamin E was provided with a high-cholesterol (1%, wt/wt) diet to rats for 5 weeks. The amount of vitamin E included in the hesperidin-free and hesperidin diets was either a low (low-E) or a normal (normal-E) level. The hesperidin supplement and different levels of dietary vitamin E did not significantly alter the concentrations of plasma triglycerides. However, the inclusion of hesperidin significantly lowered the concentration of plasma cholesterol in both the low-vitamin E group and the normal-vitamin E group compared to the hesperidin-free groups (p < 0.05). The hepatic triglyceride content was significantly lowered by the hesperidin supplement, as opposed to the plasma triglyceride content, regardless of the vitamin E level in the diet. The hepatic HMG-CoA reductase activity was significantly lowered by the hesperidin supplement with both the low-vitamin E and the normal-vitamin E compared to the hesperidin-free groups (p < 0.05). The hepatic HMG-CoA reductase activity was also significantly lowered with an increase in the dietary vitamin E within the hesperidin and hesperidin-free groups. The excretion of fecal neutral sterol and acidic sterols tended to be lower with the hesperidin supplement. Neither dietary hesperidin nor vitamin E significantly changed the hepatic antioxidant enzyme activity. This data indicates that hesperidin lowers the concentration of plasma cholesterol and the hepatic triglyceride content regardless of the dietary vitamin E level. However, the concentration of plasma cholesterol in the hesperidin-free groups was dependent on the dietary vitamin E level. This information may contribute to understanding the interactive effect of hesperidin and vitamin E on cholesterol biosynthesis in high cholesterol-fed rats.     

粗杂粮对大鼠脂代谢紊乱干预作用的机制探讨

目的观察粗杂粮对大鼠脂代谢紊乱及其脂肪组织过氧化物酶体增殖物激活受体γ (PPARγ) mRNA表达水平的影响,探讨粗杂粮改善脂代谢紊乱的作用机制。方法44只SPF级大鼠随机分为阴性对照组(饲常规饲料)和3个实验组(饲高脂饲料6周),造模成功后分别给予高脂粗杂粮、高脂米面和高脂模型饲料共15周。结果粗杂粮高脂组的血清总胆固醇(TC)、总甘油三酯(TG)、白细胞介素-6(IL-6)和C反应蛋白(CRP)显著低于高脂模型组(P<0.05),血清高密度脂蛋白胆固醇(HDL-C)水平显著高于高脂模型和米面高脂组(P<0.05),脂蛋白酯酶(LPL)和肝酯酶(HL)活性及肿瘤坏死因子-α(TNF-α)最接近阴性对照组水平;粗杂粮高脂组白色脂肪组织PPARγ mRNA的表达水平明显高于高脂模型组和米面高脂组(P<0.05)。结论复配式粗杂粮可以激活PPARγ,促进脂肪细胞LPL和HL活性逐步恢复,使血脂水平下降;同时抑制和减少IL-6、TNF-α及CRP的产生,炎症反应减轻,脂代谢紊乱得到改善。