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1.
Ectopic lipid accumulation has been observed in fish fed a high-lipid diet. However, no information is available on the mechanism by which dietary lipid levels comprehensively regulate lipid transport, uptake, synthesis and catabolism in fish. Therefore, the present study aimed to gain further insight into how dietary lipids affect lipid deposition in the liver of large yellow croaker(Larimichthys crocea). Fish (150.00±4.95 g) were fed a diet with a low (6%), moderate (12%, the control diet) or high (18%) crude lipid content for 10 weeks. Growth performance, plasma biochemical indexes, lipid contents and gene expression related to lipid deposition, including lipoprotein assembly and clearance, fatty acid uptake and triacylglycerol synthesis and catabolism, were assessed. Growth performance was not significantly affected. However, the hepato-somatic and viscera-somatic indexes as well as plasma triacylglycerol, non-esterified fatty acids and LDL-cholesterol levels were significantly increased in fish fed the high-lipid diet. In the livers of fish fed the high-lipid diet, the expression of genes related to lipoprotein clearance (LDLR) and fatty acid uptake (FABP11) was significantly up-regulated, whereas the expression of genes involved in lipoprotein assembly (apoB100), triacylglycerol synthesis and catabolism (DGAT2, CPT I) was significantly down-regulated compared with fish fed the control diet, and hepatic lipid deposition increased. In fish fed the low-lipid diet, the expression of genes associated with lipoprotein assembly and clearance (apoB100, LDLR, LRP-1), fatty acid uptake (CD36, FATP1, FABP3) and triacylglycerol synthesis (FAS) was significantly increased, whereas the expression of triacylglycerol catabolism related genes (ATGL, CPT I) was reduced compared with fish fed the control diet. However, hepatic lipid content in fish fed the low-lipid diet decreased mainly due to low dietary lipid intake. In summary, findings of this study provide molecular insight into the role of lipid deposition in the liver in response to different dietary lipid contents.  相似文献   

2.
A high-fat diet is known to induce atherosclerosis in animal models. Dietary factors and timing of atherogenic food delivery may affect plasma lipoprotein content composition and its potential atherogenic effect. Increasingly often, humans spend periods/days eating in a completely unregulated way, ingesting excessive amounts of food rich in oils and fats, alternating with periods/days when food intake is more or less correct. We investigate the effect on lipid homeostasis of a high-fat diet administered either continuously or intermittently. We investigated control pigs receiving standard diet (C, n=7), pigs receiving a high-fat diet every day for 10 weeks (CHF, n=5), and pigs receiving a high-fat diet every other week for 10 weeks (IHF, n=7). IHF animals were shown to have a different lipid profile compared with CHF animals, with a significant increase in high-density lipoproteins (HDL) levels with respect to C and CHF groups. CHF also showed significantly higher values of TC/HDL cholesterol compared with C and IHF. Hepatic expression analysis of genes involved in lipid homeostasis showed an increasing trend of nuclear receptor LXRα along with its target genes in the CHF group and in the IHF group, whereas SREBP2 and LDLr were significantly inhibited. A significant correlation was found between ABCA1 expression and circulating levels of HDL-C. Periodic withdrawals of a high-fat atherogenic diet compared with a regular administration results in a different adaptive response of lipoprotein metabolism, which leads to a significantly higher plasma level of HDL-C and lower TC/HDL-C.  相似文献   

3.
The liver is a crossroad for metabolism of lipid and carbohydrates, with acetyl-CoA serving as an important metabolic intermediate and a precursor for fatty acid and cholesterol biosynthesis pathways. A better understanding of the regulation of these pathways requires an experimental approach that provides both quantitative metabolic flux measurements and mechanistic insight. Under conditions of high carbohydrate availability, excess carbon is converted into free fatty acids and triglyceride for storage, but it is not clear how excessive carbohydrate availability affects cholesterol biosynthesis. To address this, C57BL/6J mice were fed either a low-fat, high-carbohydrate diet or a high-fat, carbohydrate-free diet. At the end of the dietary intervention, the two groups received (2)H(2)O to trace de novo fatty acid and cholesterol synthesis, and livers were collected for gene expression analysis. Expression of lipid and glucose metabolism genes was determined using a custom-designed pathway focused PCR-based gene expression array. The expression analysis showed downregulation of cholesterol biosynthesis genes and upregulation of fatty acid synthesis genes in mice receiving the high-carbohydrate diet compared with the carbohydrate-free diet. In support of these findings, (2)H(2)O tracer data showed that fatty acid synthesis was increased 10-fold and cholesterol synthesis was reduced by 1.6-fold in mice fed the respective diets. In conclusion, by applying gene expression analysis and tracer methodology, we show that fatty acid and cholesterol synthesis are differentially regulated when the carbohydrate intake in mice is altered.  相似文献   

4.
目的:探究银灵通胶囊对脂质代谢的影响及其机制。方法:建立大鼠高脂模型,用药后检测其血脂、丙二醛(MDA)、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)的活性,检测肝脏组织的高密度脂蛋白受体SR-BI、低密度脂蛋白受体(LDLR)、氧化低密度脂蛋白(ox-LDH)受体CD36蛋白表达的mRNA表达水平,检测血管组织学变化。结果:高脂饮食明显升高大鼠血清中总胆固醇(CH)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)和动脉硬化指数(AI值),银灵通胶囊组可降低上述指标,且呈一定的浓度依赖;高脂饮食可增加肝脏中SR-BI及CD36表达,降低LDLR表达,银灵通胶囊引起SR-BI的过度表达,使LDLR表达增加,CD36表达下降。高脂饮食使血清中MDA的含量增加,给予银灵通胶囊后,明显降低血清MDA的含量。结论:银灵通胶囊具有调节脂质代谢,抗动脉粥样硬化(AS)及抗脂质过氧化作用。其机制与银灵通胶囊能引起肝脏中SR-BI的过度表达及LDLR表达增加,降低肝脏中CD36表达和血清MDA含量有关。  相似文献   

5.
A long-term high-fat diet may result in a fatty liver. However, whether or not high-fat diets affect the hepatic circadian clock is controversial. The objective of this study is to investigate the effects of timed high-fat diet on the hepatic circadian clock and clock-controlled peroxisome proliferator-activated receptor (PPAR) α-mediated lipogenic gene expressions. Mice were orally administered high-fat milk in the evening for 4 weeks. The results showed that some hepatic clock genes, such as Clock, brain-muscle-Arnt-like 1 (Bmal1), Period 2 (Per2), and Cryptochrome 2 (Cry2) exhibited obvious changes in rhythms and/or amplitudes. Alterations in the expression of clock genes, in turn, further altered the circadian rhythm of PPARα expression. Among the PPARα target genes, cholesterol 7α-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl-coenzyme A reductase, low-density lipoprotein receptor, lipoprotein lipase, and diacylglycerol acyltransferase (DGAT) showed marked changes in rhythms and/or amplitudes. In particular, significant changes in the expressions of DGAT and CYP7A1 were observed. The effects of a high-fat diet on the expression of lipogenic genes in the liver were accompanied by increased hepatic cholesterol and triglyceride levels. These results suggest that timed high-fat diets at night could change the hepatic circadian expressions of clock genes Clock, Bmal1, Per2, and Cry2 and subsequently alter the circadian expression of PPARα-mediated lipogenic genes, resulting in hepatic lipid accumulation.  相似文献   

6.

Introduction

Obesity is a nutritional disorder associated with many health problems such as dyslipidemia, type 2 diabetes and cardiovascular diseases. In the present study, we investigated the anti-metabolic disorder effects of kumquat (Fortunella margarita Swingle) fruit extract (FME) on high-fat diet-induced C57BL/6 obese mice.

Methods

The kumquat fruit was extracted with ethanol and the main flavonoids of this extract were analyzed by HPLC. For the preventive experiment, female C57BL/6 mice were fed with a normal diet (Chow), high-fat diet (HF), and high-fat diet with 1% (w/w) extract of kumquat (HF+FME) for 8 weeks. For the therapeutic experiment, female C57BL/6 mice were fed with high-fat diet for 3 months to induce obesity. Then the obese mice were divided into two groups randomly, and fed with HF or HF+FME for another 2 weeks. Body weight and daily food intake amounts were recorded. Fasting blood glucose, glucose tolerance test, insulin tolerance test, serum and liver lipid levels were assayed and the white adipose tissues were imaged. The gene expression in mice liver and brown adipose tissues were analyzed with a quantitative PCR assay.

Results

In the preventive treatment, FME controlled the body weight gain and the size of white adipocytes, lowered the fasting blood glucose, serum total cholesterol (TC), serum low density lipoprotein cholesterol (LDL-c) levels as well as liver lipid contents in high-fat diet-fed C57BL/6 mice. In the therapeutic treatment, FME decreased the serum triglyceride (TG), serum TC, serum LDL-c, fasting blood glucose levels and liver lipid contents, improved glucose tolerance and insulin tolerance. Compared with the HF group, FME significantly increased the mRNA expression of PPARα and its target genes.

Conclusion

Our study suggests that FME may be a potential dietary supplement for preventing and ameliorating the obesity and obesity-related metabolic disturbances.  相似文献   

7.
8.
The effects of chronic fat overconsumption on intestinal physiology and lipid metabolism remain elusive. It is unknown whether a fat-mediated adaptation to lipid absorption takes place. To address this issue, mice fed a high-fat diet (40%, w/w) were refed or not a control diet (3%, w/w) for 3 additive weeks. Despite daily lipid intake 7.7-fold higher than in controls, fecal lipid output remained unchanged in mice fed the triglyceride (TG)-rich diet. In situ isolated jejunal loops revealed greater [1-(14)C]linoleic acid uptake without TG accumulation in mucosa, suggesting an increase in lipid absorption capacity. Induction both in intestinal mitotic index and in the expression of genes involved in fatty acid uptake, trafficking, and lipoprotein synthesis was found in high-fat diet mice. These changes were lipid-mediated, in that they were fully abolished in mice refed the control diet. A lipid load test performed in the presence or absence of the LPL inhibitor tyloxapol showed a sustained blood TG clearance in fat-fed mice likely attributable to intestinal modulation of LPL regulators (apolipoproteins C-II and C-III). These data demonstrate that a chronic high-fat diet greatly affects intestinal physiology and body lipid use in the mouse.  相似文献   

9.
This study investigated the effect of clofibrate treatment on expression of target genes of peroxisome proliferator-activated receptor (PPAR)-alpha and various genes of the lipid metabolism in liver and adipose tissue of pigs. An experiment with 18 pigs was performed in which pigs were fed either a control diet or the same diet supplemented with 5 g clofibrate/kg for 28 days. Pigs treated with clofibrate had heavier livers, moderately increased mRNA concentrations of various PPAR-alpha target genes in liver and adipose tissue, a higher concentration of 3-hydroxybutyrate, and markedly lower concentrations of triglycerides and cholesterol in plasma and lipoproteins than control pigs (P < 0.05). mRNA concentrations of sterol regulatory element-binding proteins (SREBP)-1 and -2, insulin-induced genes (Insig)-1 and Insig-2, and the SREBP target genes acetyl-CoA carboxylase, 3-methyl-3-hydroxyglutaryl-CoA reductase, and low-density lipoprotein receptor in liver and adipose tissue and mRNA concentrations of apolipoproteins A-I, A-II, and C-III in the liver were not different between both groups of pigs. In conclusion, this study shows that clofibrate treatment activates PPAR-alpha in liver and adipose tissue and has a strong hypotriglyceridemic and hypocholesterolemic effect in pigs. The finding that mRNA concentrations of some proteins responsible for the hypolipidemic action of fibrates in humans were not altered suggests that there were certain differences in the mode of action compared with humans. It is also shown that PPAR-alpha activation by clofibrate does not affect hepatic expression of SREBP target genes involved in synthesis of triglycerides and cholesterol homeostasis in liver and adipose tissue of pigs.  相似文献   

10.
目的研究豚鼠高脂饮食后高密度脂蛋白代谢的特点,并与大鼠进行比较。方法将豚鼠和大鼠分别随机分为正常组(NC)和高脂组(HF),正常组均给予普通饲料,高脂组给予高脂饲料诱导10周后,测定血清LDL-C、HDL-C水平,HDL3/HDL2比值和LCAT、CETP的表达;采用real-time RT-PCR方法检测肝脏SR-BI表达的变化。结果与正常组相比,豚鼠高脂组血清HDL-C水平显著升高,高密度脂蛋白亚型HDL3/HDL2的比值升高,血清CETP表达均显著增加,血清LCAT表达下降,肝脏SR-BI mRNA表达水平是正常组的2.27倍。而相同高脂饲料条件下,大鼠的上述指标均无明显变化。结论豚鼠摄入高脂饮食后HDL代谢与大鼠有所不同,主要表现为血清HDL-C升高,肝脏SR-BI受体表达增加,高密度脂蛋白亚型组分发生变化,大颗粒HDL2含量相对减少,小颗粒HDL3堆积,其机制与血清CETP、LCAT的变化密切相关。  相似文献   

11.
The increased uptake and storage of lipids in the liver are important features of steatotic liver diseases. The fatty acid translocase/scavenger receptor cluster of differentiation (CD)36 facilitates the hepatic uptake of lipids. We investigated if RRR-α-tocopherol (αT) alone or in combination with atorvastatin (ATV) is capable of preventing hepatic lipid accumulation via down-regulation of CD36. To this end, Dunkin Hartley guinea pigs were fed a control diet (5% fat); or a high-fat control diet (21% fat, 0.15% cholesterol); or a high-fat control diet fortified with αT (250 mg/kg diet), ATV (300 mg/kg diet) or both ATV+αT for 6 weeks. Hepatic triacylglycerols, hepatic protein and mRNA expression of CD36 as well as the mRNA expression of the controlling nuclear receptors LXRα, PXR and PPARγ were determined. Animals fed the high-fat control diet accumulated significantly more triacylglycerols in the liver than control animals. This was significantly reduced by ATV and numerically by αT and ATV+αT. Hepatic CD36 protein concentrations were significantly higher in the high-fat than in the control group, and both αT and ATV reduced CD36 expression to the level observed in the control group. However, no synergistic effect of the combined treatment was observed. Neither CD36 mRNA nor that of the nuclear receptors (LXRα, PXR and PPARγ) differed between groups, suggesting a posttranslational regulatory mechanism. Our results indicate that orally administered ATV and αT individually, but not synergistically, prevent diet-induced lipid accumulation in the liver of guinea pigs by down-regulation of hepatic CD36 protein.  相似文献   

12.
Excess energy intake correlates with the development of metabolic disorders. However, different energy-dense foods have different effects on metabolism. To compare the effects of a high-fat diet, a high-fructose diet and a combination high-fat/high-fructose diet on glucose and lipid metabolism, male C57BL/6 mice were fed with one of four different diets for 3 months: standard chow; standard diet and access to fructose water; a high fat diet; and a high fat diet with fructose water. After 3 months of feeding, the high-fat and the combined high-fat/high-fructose groups showed significantly increased body weights, accompanied by hyperglycemia and insulin resistance; however, the high-fructose group was not different from the control group. All three energy-dense groups showed significantly higher visceral fat weights, total cholesterol concentrations, and low-density lipoprotein cholesterol concentrations compared with the control group. Assays of basal metabolism showed that the respiratory quotient of the high-fat, the high-fructose, and the high-fat/high-fructose groups decreased compared with the control group. The present study confirmed the deleterious effect of high energy diets on body weight and metabolism, but suggested that the energy efficiency of the high-fructose diet was much lower than that of the high-fat diet. In addition, fructose supplementation did not worsen the detrimental effects of high-fat feeding alone on metabolism in C57BL/6 mice.  相似文献   

13.
14.

This study investigated different dietary strategies, high-fat (HFd), or standard diet (Sd) alone or in combination with standardized Aronia melanocarpa extract (SAE), as a polyphenol-rich diet, and their effects on lipids and fatty acids (FA) in rats with metabolic syndrome (MetS). Wistar albino rats were randomly divided into two groups: healthy and rats with MetS, and then depending on dietary patterns on six groups: healthy rats fed with Sd, healthy rats fed with Sd and SAE, rats with MetS fed with HFd, rats with MetS fed with HFd and SAE, rats with MetS fed with Sd, and rats with MetS fed with Sd and SAE. 4 weeks later, after an overnight fast (12–14 h), blood for determination of total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), index of lipid peroxidation (measured as TBARS), and FA was collected. Increased FA and lipid concentration found in MetS rats were reduced when changing dietary habits from HFd to Sd with or without SAE consumption. Consumption of SAE slightly affects the FA profiles, mostly palmitoleic acid in healthy rats and PUFA in MetS?+?HFd rats. Nevertheless, in a high-fat diet, SAE supplementation significantly decreases n-6/n-3 ratio, thereby decreasing systemic inflammation. Further researches are warranted to confirm these effects in humans.

  相似文献   

15.
The effect was examined of dietary sericin on the lipid and carbohydrate metabolism in rats fed with a high-fat diet. The rats were fed with a 20% beef tallow diet with or without sericin at the level of 4% for 5 weeks. The final body weight and white adipose tissue weight were unaffected by dietary manipulation. The consumption of sericin significantly reduced the serum levels of triglyceride, cholesterol, phospholipids and free fatty acids. Serum very-low-density lipoprotein (VLDL)-triglyceride, VLDL-cholesterol, low-density lipoprotein (LDL)-cholesterol and LDL-phospholipids were also significantly reduced by the sericin intake. Liver triglyceride and the activities of glucose 6-phosphate dehydrogenase and malic enzyme, the lipogenic enzymes, were also reduced by the sericin intake. Dietary sericin caused a marked elevation in serum adiponectin. The consumption of sericin suppressed the increases in plasma glucose and insulin levels after an intraperitoneal glucose injection. These results imply the usefulness of sericin for improving the lipid and carbohydrate metabolism in rats fed on a high-fat diet.  相似文献   

16.
Cardiovascular diseases (CVDs) are the most common cause of death in patients with nonalcoholic fatty liver disease (NAFLD) and dyslipidemia is considered at least partially responsible for the increased CVD risk in NAFLD patients. The aim of the present study is to understand how hepatic de novo lipogenesis influences hepatic cholesterol content as well as its effects on the plasma lipid levels. Hepatic lipogenesis was induced in mice by feeding a fat-free/high-sucrose (FF/HS) diet and the metabolic pathways associated with cholesterol were then analyzed. Both liver triglyceride and cholesterol contents were significantly increased in mice fed an FF/HS diet. Activation of fatty acid synthesis driven by the activation of sterol regulatory element binding protein (SREBP)-1c resulted in the increased liver triglycerides. The augmented cholesterol content in the liver could not be explained by an increased cholesterol synthesis, which was decreased by the FF/HS diet. HMG-CoA reductase protein level was decreased in mice fed an FF/HS diet. We found that the liver retained more cholesterol through a reduced excretion of bile acids, a reduced fecal cholesterol excretion, and an increased cholesterol uptake from plasma lipoproteins. Very low-density lipoprotein-triglyceride and -cholesterol secretion were increased in mice fed an FF/HS diet, which led to hypertriglyceridemia and hypercholesterolemia in Ldlr-/- mice, a model that exhibits a more human like lipoprotein profile. These findings suggest that dietary cholesterol intake and cholesterol synthesis rates cannot only explain the hypercholesterolemia associated with NAFLD, and that the control of fatty acid synthesis should be considered for the management of dyslipidemia.  相似文献   

17.
Hyperlipidemia is a major risk factor for developing atherosclerosis in humans, and epidemiological studies have correlated specific lipoprotein levels with cardiovascular disease risk. Murine models of atherosclerosis rely on the induction of hyperlipidemia for vascular lesions to form, but the pathogenic contributions attributed to different lipoprotein populations are not well defined. To address this issue, we analyzed over 300 LDL receptor (LDLR) deficient mice that have been fed a high-fat diet and for which a full lipoprotein profile and aortic root atherosclerosis values were assessed. Overall, aortic root atherosclerosis is best predicted by plasma VLDL cholesterol levels with less predictive value derived from either LDL or HDL cholesterol. Triglyceride levels are more atherogenic in female mice, especially immune competent females, and depletion of the adaptive immune system leads to a global reduction in plasma lipid levels and aortic root lesion size yet does not appear to alter the atherogenic potential of individual lipoprotein subspecies. In contrast, HDL-cholesterol is a better predictor of aortic root atherosclerosis in apoE-deficient mice. In summary, this large scale analysis of high-fat diet fed LDLR deficient mice highlight the relationship between different plasma lipid components, especially VLDL-cholesterol, and aortic root atherosclerosis.  相似文献   

18.
Insulin resistance and hepatic steatosis are the most common complications of obesity. Pitaya is an important source of phytochemicals such as polyphenols, flavonoid and vitamin C which are related to its antioxidant activity. The present study was conducted to evaluate the influence of white pitaya juice (WPJ) on obesity-related metabolic disorders (e.g. insulin resistance and hepatic steatosis) in high-fat diet-fed mice. Forty-eight male C57BL/6J mice were assigned into four groups and fed low-fat diet with free access to water or WPJ, or fed high-fat diet with free access to water or WPJ for 14 weeks. Our results showed that administration of WPJ improved high-fat diet-induced insulin resistance, hepatic steatosis and adipose hypertrophy, but it exerted no influence on body weight gain in mice. Hepatic gene expression analysis indicated that WPJ supplement not only changed the expression profile of genes involved in lipid and cholesterol metabolism (Srebp1, HMGCoR, Cpt1b, HL, Insig1 and Insig2) but also significantly increased the expression levels of FGF21-related genes (Klb, FGFR2, Egr1 and cFos). In conclusion, WPJ protected from diet-induced hepatic steatosis and insulin resistance, which was associated with the improved FGF21 resistance and lipid metabolism.  相似文献   

19.
The aim of this study was to investigate the metabolic effects of a dietary supplement of powdered rose hip to C57BL/6J mice fed a high-fat diet (HFD). Two different study protocols were used; rose hip was fed together with HFD to lean mice for 20 wk (prevention study) and to obese mice for 10 wk (intervention study). Parameters related to obesity and glucose tolerance were monitored, and livers were examined for lipids and expression of genes and proteins related to lipid metabolism and gluconeogenesis. A supplement of rose hip was capable of both preventing and reversing the increase in body weight and body fat mass imposed by a HFD in the C57BL/6J mouse. Oral and intravenous glucose tolerance tests together with lower basal levels of insulin and glucose showed improved glucose tolerance in mice fed a supplement of rose hip compared with control mice. Hepatic lipid accumulation was reduced in mice fed rose hip compared with control, and the expression of lipogenic proteins was downregulated, whereas AMP-activated protein kinase and other proteins involved in fatty acid oxidation were unaltered. Rose hip intake lowered total plasma cholesterol as well as the low-density lipoprotein-to-high-density lipoprotein ratio via a mechanism not involving altered gene expression of sterol regulatory element-binding protein 2 or 3-hydroxymethylglutaryl-CoA reductase. Taken together, these data show that a dietary supplement of rose hip prevents the development of a diabetic state in the C57BL/6J mouse and that downregulation of the hepatic lipogenic program appears to be at least one mechanism underlying the antidiabetic effect of rose hip.  相似文献   

20.
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