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1.
The effect of dietary conjugated linoleic acid (CLA) on hepatic lipid parameters in Sprague-Dawley rats was examined. When rats were fed a diet containing CLA at 0 (control), 1, or 2% of the weight of the amount of food given for 3 weeks, the liver weight exhibited a slight increase in the CLA-fed groups, although the difference was not significant. Lipid accumulation in the hepatocytes of CLA-fed rats was also demonstrated by electron microscopic observation. In addition, the liver thiobarbituric acid reactive substances levels were significantly higher in the 2 wt % CLA group than in the other two dietary groups, and the levels of phosphatidylcholine hydroperoxide were higher in CLA-fed groups when compared to that of the control group. On the other hand, the serum lipid peroxide levels were comparable among all three dietary groups. Levels of triglycerides in the white adipose tissue (WAT) and serum nonesterified fatty acid (NEFA) were reduced in a CLA-dose-dependent manner. CLA was shown to accumulate in the WAT much more than in the serum or liver. These results suggest that CLA accelerates the decomposition of storage lipids in WAT and the clearance of serum NEFA levels, resulting in lipid peroxidation and a morphological change in the liver.  相似文献   

2.
Conjugated linoleic acid (CLA) strongly prevents fat accumulation in adipose tissue of mice, even if hepatic fat deposition and insulin resistance are concomitantly observed. This study investigated the possibility of maintaining the antiadiposity properties of CLA while preventing adverse effects such as liver steatosis and hyperinsulinemia. To this end, mice were divided into three groups and fed a standard diet (control) or a diet supplemented with 1% CLA (CLA) or a mixture of 1% CLA plus 7.5% pine nut oil (CLA + P). The combination of CLA + P preserved the CLA-mediated antiadiposity properties (70% fat reduction), preventing hepatic steatosis and a sharp increase in plasmatic insulin starting from the eighth week of CLA treatment. The assay of both fatty acid synthesis and oxidation in the CLA + P mice revealed a time-dependent biphasic behavior of the corresponding enzymatic activities. A sudden change in these metabolic events was indeed found at the eighth week. A strong correlation between the changes in key enzymes of lipid metabolism and in insulin levels apparently exists in CLA-fed mice. Furthermore, lower levels of lipids, in comparison to values found in CLA-fed mice, were observed in the liver and plasma of CLA + P-fed animals.  相似文献   

3.
Dietary conjugated linoleic acid (CLA; 0-2.0%) increased CLA concentrations in liver microsomes and skeletal muscle homogenates from rats. Dietary CLA decreased oleic and arachadonic acid concentrations in both liver microsomes and skeletal muscle. The presence of CLA in liver microsomes had no impact on linoleic acid, arachadonic acid, and alpha-tocopherol oxidation rates. Dietary CLA (2.0%) also did not alter alpha-tocopherol oxidation rates in liver microsomes or muscle homogenates. Formation of malonaldehyde (MDA) in oxidizing liver microsomes decreased with increasing CLA concentration as determined by measurement of thiobarbituric acid-MDA complexes by HPLC. The ability of CLA to decrease MDA formation without impacting other lipid oxidation markers such as the disappearance of fatty acid and alpha-tocopherol suggests that decreased MDA concentration was the result of CLA's ability to lower polyenoic fatty acids such as arachadonic acid. While CLA does not appear to act as an antioxidant, its ability to decrease polyenoic fatty acid concentrations could decrease the formation of highly cytotoxic lipid oxidation products such as MDA.  相似文献   

4.
We investigated the effects of the oral administration of lophenol (Lo) and cycloartanol (Cy), two kinds of antidiabetic phytosterol isolated from Aloe vera , on glucose and lipid metabolism in Zucker diabetic fatty (ZDF) rats. We demonstrated that the administrations of Lo and Cy suppressed random and fasting glucose levels and reduced visceral fat weights significantly. It was also observed that treatments with Lo and Cy decreased serum and hepatic lipid concentrations (triglyceride, nonesterified fatty acid, and total cholesterol). Additionally, Lo and Cy treatments resulted in a tendency for reduction in serum monocyte chemotactic protein-1 (MCP-1) level and an elevation in serum adiponectin level. Furthermore, the expression levels of hepatic genes encoding gluconeogenic enzymes (G6 Pase, PEPCK), lipogenic enzymes (ACC, FAS), and SREBP-1 were decreased significantly by the administrations of aloe sterols. In contrast, Lo and Cy administration increased mRNA levels of glycolysis enzyme (GK) in the liver. It was also observed that the hepatic β-oxidation enzymes (ACO, CPT1) and PPARα expressions tended to increase in the livers of the Lo- and Cy-treated rats compared with those in ZDF-control rats. We therefore conclude that orally ingested aloe sterols altered the expressions of genes related to glucose and lipid metabolism, and ameliorated obesity-associated metabolic disorders in ZDF rats. These findings suggest that aloe sterols could be beneficial in preventing and improving metabolic disorders with obesity and diabetes in rats.  相似文献   

5.
The aim of this study was to determine the effect of chronic dietary supplementation of a grape seed proanthocyanidin extract (GSPE) at a dose of 35 mg/kg body weight on energy metabolism and mitochondrial function in the skeletal muscle of Zucker obese rats. Three groups of 10 animals each were used: lean Fa/fa lean group (LG) rats, a control fa/fa obese group (OG) of rats, and an obese supplemented fa/fa proanthocyanidins obese group (POG) of rats, which were supplemented with a dose of 35 mg GSPE/kg of body weight/day during the 68 days of experimentation. Skeletal muscle energy metabolism was evaluated by determining enzyme activities, key metabolic gene expression, and immunoblotting of oxidative phosphorylation complexes. Mitochondrial function was analyzed by high-resolution respirometry using both a glycosidic and a lipid substrate. In muscle, chronic GSPE administration decreased citrate synthase activity, the amount of oxidative phosphorylation complexes I and II, and Nrf1 gene expression, without any effects on the mitochondrial oxidative capacity. This situation was associated with lower reactive oxygen species (ROS) generation. Additionally, GSPE administration enhanced the ability to oxidize pyruvate, and it also increased the activity of enzymes involved in oxidative phosphorylation including cytochrome c oxidase. There is strong evidence to suggest that GSPE administration stimulates mitochondrial function in skeletal muscle specifically by increasing the capacity to oxidize pyruvate and contributes to reduced muscle ROS generation in obese Zucker rats.  相似文献   

6.
It was reported that increased plasma levels of free fatty acids (FFAs) are associated with profound insulin resistance in skeletal muscle and may also play a critical role in the insulin resistance of obesity and type 2 diabetes mellitus. Skeletal muscle is the major site for insulin-stimulated glucose uptake and is involved in energy regulation and homeostasis. In this study, we used 12-O-tetradecanoylphorbol 13-acetate (TPA), a protein kinase C (PKC) activator, and palmitate to induce insulin resistance in C2C12 mouse skeletal muscle cells. Our data show that epigallocatechin gallate (EGCG) and curcumin treatment reduce insulin receptor substrate-1 (IRS-1) Ser307 phosphorylation, and curcumin is more potent to increase Akt phosphorylation in TPA induction. Moreover, we found that after 5 h of palmitate incubation, epicatechin gallate (ECG) can suppress IRS-1 Ser307 phosphorylation and significantly promote Akt, ERK1/2, p38 MAPK, and AMP-activated protein kinase activation. With a longer incubation with palmitate, IRS-1 exhibited a dramatic depletion, and treatment with EGCG, ECG, and curcumin could reverse IRS-1 expression, Akt phosphorylation, and MAPK signaling cascade activation and improve glucose uptake in C2C12 skeletal muscle cells, especially ECG and curcumin. In addition, treatment with these polyphenols can suppress acetyl-CoA carboxylase activation, but only EGCG could inhibit lipid accumulation in the intracellular site. These findings may suggest that curcumin shows the best capacity to improve FFA-induced insulin resistance than the other two, and ECG was more effective than EGCG in attenuating insulin resistance.  相似文献   

7.
High content isoflavone soy protein (SBP) (Abalon) has been found in animal studies to possess beneficial effects on a number of the characteristic features of the insulin resistance syndrome. The aim of this study was to investigate whether SBP exerts beneficial effects on metabolism in the diabetic KKAy-mouse. Furthermore, we investigated the long-term in vivo effect of SBP on the expression profile in islets of key insulin regulatory genes. Twenty KKAy-mice, aged 5 weeks, were divided into 2 groups and treated for 9 weeks with either (A) standard chow diet (control) or (B) chow + 50% SBP. Twenty normal C57BL-mice fed with standard chow diet served as nondiabetic controls (C). Blood samples were collected and analyzed before and after intervention. Gene expression was determined in islets by quantitative real-time RT-PCR and Affymetrix microarray. It was demonstrated that long-term treatment with SBP improves glucose homeostasis, increases insulin sensitivity, and lowers plasma triglycerides in diabetic KKAy-mice. SBP reduces fasting plasma glucose, insulin, triglycerides, and total cholesterol. Furthermore, SBP markedly changes the gene expression profile of key insulin regulatory genes GLUT2, GLUT3, Ins1, Ins2, IGF1, Beta2/Neurod1, cholecystokinin, and LDLr, and proliferative genes in islets isolated from KKAy-mice. After 9 weeks of treatment with SBP, plasma glucose and insulin homeostasis was normalized compared to start levels. The results indicate that SBP improves glucose and insulin sensitivity and up-regulates the expression of key insulin regulatory genes.  相似文献   

8.
In this study, we evaluated the effect of a highly methoxylated apple pectin (HMAP) on cardiometabolic risk factors in Zucker fatty rats. beta-Glucan, a fiber known for its hypocholesterolemic properties, also was used. The rats fed both fiber-enriched diets exhibited a reduction in body weight and in total cholesterol and triglycerides when compared to the Zucker fatty rats fed the standard diet. The effect on the lipid profile was more remarkable in the HMAP group. A decrease in blood glucose was only noticed in this group. Moreover, a decrease in plasma insulin, HOMA-IR, and HOMA-beta was noticed in the fiber groups, and in particular in the HMAP group, these variables being similar to the lean rats. Blood pressure and endothelial function were similar in all the Zucker fatty rats. These results warrant evaluation in humans to determine if HMAP could be used as a functional ingredient to reduce lipid profile, insulin resistance, and other cardiometabolic risk factors.  相似文献   

9.
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10.
The effect of allantoin, an active component of yam, on plasma glucose of streptozotocin-induced diabetic rats (STZ-diabetic rats) is investigated. Allantoin decreased plasma glucose levels in a dose-related manner, which was reduced by pretreatment with naloxone or naloxonazine. A concomitant increase in plasma β-endorphin, detected by enzyme-linked immunosorbent assay, was observed. Moreover, allantoin enhanced β-endorphin release from the isolated adrenal medulla of STZ-diabetic rat in a dose-related manner. However, its plasma glucose lowering action was reduced but not totally abolished by bilateral adrenalectomy. Furthermore, allantoin directly increased radioactive glucose uptake in isolated skeletal muscle, and repeated administration for 3 days increased GLUT4 mRNA and protein levels in muscle. This effect was markedly reduced in STZ-diabetic rats with bilateral adrenalectomy. This study suggests that allantoin increases GLUT4 gene expression in muscle by increasing β-endorphin secretion from the adrenal gland in STZ-diabetic rats.  相似文献   

11.
The purpose of this study was to investigate the distinct roles of advanced glycation end products (AGEs) on insulin-mediated glucose disposal in 3T3-L1 adipocytes and C2C12 skeletal muscle cells. AGE-modified proteins, namely, GO-AGEs, were prepared by incubating bovine serum albumin (BSA) with glyoxal (GO) for 7 days. Glucose utilization rates and the expression of insulin signaling-associated proteins, including Akt, insulin receptor substrate-1, and glucose transporter 4, were determined. GO-AGEs caused insulin resistance (IR) by suppressing insulin-stimulated glucose uptake both in 3T3-L1 adipocytes and C2C12 muscle cells. Interestingly, an unexpected finding was that insulin-stimulated glucose transport in adipocytes was affected by GO-AGEs in a biphasic manner, with an initial steep increase (168%) during the first 8 h of incubation followed by a significantly impaired uptake after extended culture times (24-48 h, p < 0.05). Treatment with GO-AGEs for 24 h markedly accelerated lipid droplet formation compared to the BSA control; however, it was blocked by incubation with an anti-RAGE antibody. Our study suggests that GO-AGEs induce an early dramatic elevation of glucose transport in adipocytes that may be related to the activation of insulin signaling; however, subsequent IR may result from increased oxidative stress and proinflammatory TNF-α production.  相似文献   

12.
Recent studies have shown that dietary phospholipids, especially phosphatidylcholine and phosphatidylserine, have various beneficial biological effects. However, there are not enough data concerning the physiological function of dietary phosphatidylinositol (PI). The metabolic syndrome, a cluster of metabolic abnormalities such as dyslipidemia, diabetes mellitus, and hypertension, is a widespread and increasingly prevalent disease in industrialized countries. Nonalcoholic fatty liver disease (NAFLD) is often associated with features of the metabolic syndrome. NAFLD describes the spectrum of liver damage ranging from hepatic steatosis to steatohepatitis, liver fibrosis, and cirrhosis, and it is emerging as the most common liver disease worldwide. The present study examined whether dietary PI protects Zucker ( fa/ fa) rats from the metabolic syndrome. For 4 weeks, rats were fed semisynthetic diets containing either 7% soybean oil or 5% soybean oil plus 2% PI. Dietary PI markedly prevented the development of hepatomegaly and hepatic steatosis and lowered hepatic injury markers in serum. Additionally, hyperinsulinemia was relieved by the feeding of dietary PI in Zucker rats. These effects were attributable to an increase in serum adiponectin, enhancement of fatty acid beta-oxidation, and suppression of mRNA expression of inflammatory genes in the liver. This is the first report that dietary PI increases serum adiponectin level and prevents the development of NAFLD in a rat model of the metabolic syndrome.  相似文献   

13.
Catalpol is one of the active principles from roots of Rehmannia glutinosa Steud (Scrophulariaceae) that is widely used to treat diabetic disorders in Chinese traditional medicine using the name of Di-Huang, which is used to investigate the mechanisms for lowering of plasma glucose in streptozotocin-induced diabetic rats (STZ-diabetic rats). Catalpol decreased plasma glucose in a dose-related manner, and this action was reduced by pretreatment with naloxone or naloxonazine. An increase of plasma β-endorphin by catalpol was also observed in parallel. The plasma glucose lowering action of catalpol was deleted in bilateral adrenalectomized rats. Moreover, catalpol enhanced β-endorphin release from the isolated adrenal medulla of STZ-diabetic rats. Otherwise, plasma glucose lowering action of catalpol failed to produce in opioid μ-receptor knockout mice. Also, repeated administration of catalpol for 3 days in STZ-diabetic rats resulted in a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver and an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle. These effects were also reversed by blockade of opioid μ-receptors. Our results suggested that catalpol increased glucose utilization through increase of β-endorphin secretion from adrenal gland in STZ-diabetic rats.  相似文献   

14.
We investigated the effects of erythritol on rats with streptozotocin- (STZ-) induced diabetes mellitus. Oral administration of erythritol [100, 200, or 400 mg (kg body weight)(-1) day(-1) for 10 days] to rats with STZ-induced diabetes resulted in significant decreases in the glucose levels of serum, liver, and kidney. Erythritol also reduced the elevated serum 5-hydroxymethylfurfural level that is glycosylated with protein as an indicator of oxidative stress. In addition, thiobarbituric acid-reactive substance levels of serum and liver and kidney mitochondria were dose-dependently lower in the erythritol-treated groups than in the control diabetic group. Furthermore, the serum creatinine level was reduced by oral administration of erythritol in a dose-dependent manner. These results suggest that erythritol affects glucose metabolism and reduces lipid peroxidation, thereby improving the damage caused by oxidative stress involved in the pathogenesis of diabetes.  相似文献   

15.
We investigated the effect of dietary combination of conjugated linoleic acid (CLA) and docosahexaenoic acid (DHA) to attenuate CLA-induced fatty liver in C57BL/6N mice. Mice were fed semisynthetic diets that contained either 6% high linoleic safflower oil (HL-SAF), 4% HL-SAF + 2% CLA, or 3.5% HL-SAF + 2% CLA + 0.5% DHA for 4 weeks. This 4 week feeding of CLA showed hepatic lipid accumulation concomitant with the decrease in adipose tissue weight in mice. However, 0.5% supplementation of DHA to the CLA diet could alleviate fatty liver without decreasing the antiobesity effect of CLA. The CLA diet promoted fatty acid synthesis in the liver, but DHA supplementation significantly attenuated the increase in enzyme activity induced by CLA. On the other hand, serum adipocytokines, leptin and adiponectin, were drastically decreased by CLA feeding, and DHA supplementation did not affect those levels. These results show that DHA supplementation to the CLA diet can attenuate CLA-induced fatty liver through the reduction of hepatic fatty acid synthesis without affecting adipocytokine production in C57BL/6N mice.  相似文献   

16.
Fucoxanthin is a marine carotenoid found in edible brown seaweeds. We previously reported that dietary fucoxanthin attenuates the weight gain of white adipose tissue (WAT) of diabetic/obese KK- A(y) mice. In this study, to evaluate the antiobesity and antidiabetic effects of fucoxanthin and fish oil, we investigated the effect on the WAT weight, blood glucose, and insulin levels of KK- A(y) mice. Furthermore, the expression level of uncoupling protein 1 (UCP1) and adipokine mRNA in WAT were measured. After 4 weeks of feeding, 0.2% fucoxanthin in the diet markedly attenuated the gain of WAT weight in KK- A(y) mice with increasing UCP1 expression compared with the control mice. The WAT weight of the mice fed 0.1% fucoxanthin and 6.9% fish oil was also significantly lower than that of the mice fed fucoxanthin alone. In addition, 0.2% fucoxanthin markedly decreased the blood glucose and plasma insulin concentrations in KK- A(y) mice. The mice fed with the combination diet of 0.1% fucoxanthin and fish oil also showed improvements similar to that of 0.2% fucoxanthin. Leptin and tumor necrosis factor (TNFalpha) mRNA expression in WAT were significantly down-regulated by 0.2% fucoxanthin. These results suggest that dietary fucoxanthin decreases the blood glucose and plasma insulin concentration of KK- A(y) along with down-regulating TNFalpha mRNA. In addition, the combination of fucoxanthin and fish oil is more effective for attenuating the weight gain of WAT than feeding with fucoxanthin alone.  相似文献   

17.
The aim of this study was to elucidate the effect of fish-oil-derived monounsaturated fatty acids (MUFAs) containing large amounts of C20:1 and C22:1 isomers on metabolic disorders in mice. Male C57BL/6J mice were fed a 32% lard diet (control) or a 27% lard plus 5% saury-oil-derived MUFA diet for 6 weeks. Dietary MUFA improved insulin resistance and alleviated metabolic syndrome risk factors by reducing blood glucose and lipids. These favorable changes may be attributed to an improved adipocytokine profile. MUFA ingestion resulted in favorable changes in mRNA expression of genes involved in glucose/lipid metabolism (SCD-1, CPT1a, UCPs, and CS) as well as inflammation (MAC1, MMP3, and SAA3) and alterations in fatty acid composition. Our data suggest that marine MUFA improved glucose/lipid homeostasis and hindered the development of metabolic syndrome in obese mice.  相似文献   

18.
《Cereal Chemistry》2017,94(3):424-429
The effect of rice bran ethanolic extract from Superjami, a new blackish‐purple pigmented cultivar, on the lipid and glucose metabolisms in a postmenopausal‐like model of ovariectomized rats was investigated. Sprague‐Dawley female rats were subjected to either bilateral ovariectomy or a sham operation and randomly divided into three dietary groups (n = 6): sham‐operated fed with normal diet (SHAM), ovariectomized fed with normal diet (OVX‐AIN76), and ovariectomized fed with normal diet supplemented with Superjami bran extract (OVX‐SJ). The OVX‐AIN76 group showed significantly higher body weight, triglyceride, total cholesterol, blood glucose, and insulin than the SHAM group. On the other hand, supplementation of Superjami bran extract markedly reduced the body weight gain and improved the lipid and glucose profiles in ovariectomized rats through inhibition of hepatic lipogenesis and adipokine production and modulation of glucose‐regulating enzyme activities. These findings demonstrate that extracts from Superjami bran may be useful in the prevention and management of postmenopause‐induced hyperlipidemia and hyperglycemia.  相似文献   

19.
Yerba maté (Ilex paraguariensis) is rich in polyphenols, especially chlorogenic acids. Evidence suggests that dietary polyphenols could play a role in glucose absorption and metabolism. The aim of this study was to evaluate the antidiabetic properties of yerba maté extract in alloxan-induced diabetic Wistar rats. Animals (n = 41) were divided in four groups: nondiabetic control (NDC, n = 10), nondiabetic yerba maté (NDY, n = 10), diabetic control (DC, n = 11), and diabetic yerba maté (DY, n = 10). The intervention consisted in the administration of yerba maté extract in a 1 g extract/kg body weight dose for 28 days; controls received saline solution only. There were no significant differences in serum glucose, insulin, and hepatic glucose-6-phosphatase activity between the groups that ingested yerba maté extract (NDY and DY) and the controls (NDC and DC). However, the intestinal SGLT1 gene expression was significantly lower in animals that received yerba maté both in upper (p = 0.007) and middle (p < 0.001) small intestine. These results indicate that bioactive compounds present in yerba maté might be capable of interfering in glucose absorption, by decreasing SGLT1 expression.  相似文献   

20.
Silkworms with conjugated linoleic acid (CLA) incorporated into their lipids (designated CLA silkworms) were produced to enhance the quality of silkworms having a synergistic effect with CLA functions by dietary synthetic CLA. Silkworm larvae were fed fresh mulberry leaves (control diet) until the third instar stage and were then subjected to various levels (0%, 0.1%, 1%, 5%, and 10%) of CLA-sprayed mulberry leaves (designated CLA diet) beginning on the first day of the fourth instar stage and continuing to the third day of the fifth instar stage. CLA contents in CLA silkworms increased proportionally with increasing CLA levels of CLA diets. CLA silkworms on a 1% CLA diet contained 2.2 g CLA/100 g lipid without body weight reduction, whereas CLA silkworms on a 10% CLA diet contained 14.8 g CLA/100 g lipid with a significant reduction of body weight, relative to the control silkworms. The CLA content in the lipids of CLA silkworms on a 10% CLA diet was significantly higher than that of CLA silkworms on a 5% CLA diet. A 0.1% CLA diet was not sufficient to accumulate CLA in the silkworms. Most of the CLA (approximately 99%) of silkworm lipids was present in triglyceride (TG) with a similar ratio of c9,t11 and t10,c12 CLA isomers. These results suggest that a 1% CLA diet was suitable for the production of CLA silkworms.  相似文献   

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