Low-dose fish oil consumption prevents hepatic lipid accumulation in high cholesterol diet fed mice

We examined the effects of low-dose fish oil ingestion on hepatic lipid accumulation caused after high cholesterol feeding in C57BL/6J mice. The mice were fed purified experimental diets consisting of 20 energy % (en%) safflower oil (SO or SO/CH), 2 en% fish oil + 18 en% safflower oil (2FO or 2FO/CH), or 5 en% fish oil + 15 en% safflower oil (5FO or 5FO/CH) with or without 2 weight % (wt %) cholesterol for 8 weeks. Hepatic triglyceride and total cholesterol contents were significantly lower in groups that were fed diets containing fish oil and cholesterol than in those that were fed safflower oil and cholesterol. The hepatic mRNA levels of fatty acid synthase (FAS) were lower in groups fed cholesterol or fish oil. Fatty acid oxidation-related hepatic gene expressions were higher in fish oil-fed groups. Fecal cholesterol excretion was higher in all cholesterol-fed groups; cholesterol excretion was high in groups fed fish oil and cholesterol. These results suggest that low-dose fish oil diets improve lipid metabolism by modifying the expression of lipid metabolism-related genes in the liver and increasing fecal cholesterol excretion.     

Interactions of lipid metabolism and intestinal physiology with Tremella fuciformis Berk edible mushroom in rats fed a high-cholesterol diet with or without Nebacitin

Male adult Wistar rats were randomly divided into six groups in a 2 x 3 factorial design and fed diets containing different levels of Tremella fuciformis Berk (TFB) dietary fiber (0, 5, or 10%) and 1 g of cholesterol/100 g of diet with or without 0.7% Nebacitin for 4 weeks. TFB contained 6.2% soluble dietary fiber and 57.3% insoluble dietary fiber. The results showed that the serum LDL-cholesterol, hepatic total cholesterol, and triglyceride levels were significantly decreased (P < 0.05) in the rats fed diets with TFB content with or without Nebacitin. However, the serum total cholesterol, VLDL-cholesterol, and triglyceride levels were significantly decreased (P < 0.05) by Nebacitin. In feces, the presence of TFB (T5, T10, AT5, and AT10) in the diet significantly increased the total neutral steroids and bile acid excretions and undigested fiber concentrations as compared to T0 or AT0. In the small intestine, the Nebacitin diets increased the weights of both cecum and colon-rectum contents and lowered short-chain fatty acid (SCFA) concentrations of serum and cecal contents more than no Nebacitin diets did. It was suggested that the hypocholesterolemic effect of TFB dietary fiber may be mediated by the increase in fecal neutral steroids and total bile acids excretion and the increase in SCFA productions. The TFB edible mushroom dietary supplement altered the intestinal physiology of the rats.     

Hypolipidemic effect of soluble fiber isolated from seeds of Cassia tora Linn. in rats fed a high-cholesterol diet

Soluble fibers isolated from the seeds of Cassia tora Linn. (SFC) have attracted considerable attention in recent years due to their phenomenal rheological behavior. In this study were investigated the effects of SFC on lipid metabolism. Male Sprague-Dawley rats were fed one of three experimental diets, a normal diet, a high-cholesterol diet, or a high-cholesterol diet with 5% SFC, for 5 weeks. The serum concentration of total cholesterol in rats fed SFC was 27% lower (p < 0.05) compared to that of the control group, but the serum high-density lipoprotein cholesterol level was increased in the SFC group. Liver total cholesterol and triglyceride levels were reduced significantly (p < 0.05) in rats fed the SFC diet. In addition, fecal bile acid and lipid excretion was significantly increased by SFC consumption. These results indicate that SFC enhances fecal lipid excretion and may cause a reduction in serum and hepatic lipid concentrations in rats.     

Antihyperlipidemic and body fat-lowering effects of silk proteins with different fibroin/sericin compositions in mice fed with high fat diet

The effect of silk protein with different fibroin/sericin compositions on body weight and lipid metabolism in high fat-fed mice was investigated. The animals were given experimental diets for 6 weeks: normal control (NC), high fat (HF) and high fat diet supplemented with F100 (pure fibroin, HF-F100), F81 (81:19 fibroin/sericin, w/w, HF-F81) or F50 (50:50 fibroin/sericin, w/w, HF-F50). The silk protein-fed mice showed markedly reduced body weight and enhanced lipid profile relative to the HF group. In general, the amount of body fat, triglyceride and total plasma cholesterol levels, atherogenic index and free fatty acid level tended to decrease, while the HDL-cholesterol level increased, with increased amount of sericin in the diet. This hypolipidemic effect was partly due to increased fecal lipid excretion, inhibition of lipogenesis and regulation of adipokine production. These findings illustrate that silk protein, particularly sericin, may be beneficial in the prevention of high fat diet-induced hyperlipidemia and obesity.     

Micronutrient-enriched rapeseed oils improve the brain oxidant/antioxidant system in rats fed a high-fat diet

The main proposal of this study was to evaluate in vivo whether micronutrient-enriched rapeseed oils obtained using different crushing and refining procedures and characterized by different quantities and qualities of micronutrients (optimized oils) could have any beneficial effect on the antioxidant status of the brain. Sprague-Dawley rats were fed a high-fat diet for 4 weeks. The lipid source consisted of 20% optimized rapeseed oils with different quantities and qualities of micronutrients. The control group received traditional refined rapeseed oil. The experimental optimized oils decreased lipid peroxidation and increased endogenous antioxidant status in parallel with the enhancement of micronutrients. No alteration in acetylcholinesterase activity was induced by the high-fat diet in any experimental group. These results indicate that a regular intake of optimized rapeseed oils can prevent oxidative stress, providing evidence that optimized rapeseed oils could be a functional food with potentially important neuroprotective properties.     

Dietary supplementation of grape skin extract improves glycemia and inflammation in diet-induced obese mice fed a Western high fat diet

Dietary antioxidants may provide a cost-effective strategy to promote health in obesity by targeting oxidative stress and inflammation. We recently found that the antioxidant-rich grape skin extract (GSE) also exerts a novel anti-hyperglycemic activity. This study investigated whether 3-month GSE supplementation can improve oxidative stress, inflammation, and hyperglycemia associated with a Western diet-induced obesity. Young diet-induced obese (DIO) mice were randomly divided to three treatment groups (n = 12): a standard diet (S group), a Western high fat diet (W group), and the Western diet plus GSE (2.4 g GSE/kg diet, WGSE group). By week 12, DIO mice in the WGSE group gained significantly more weight (24.6 g) than the W (20.2 g) and S groups (11.2 g); the high fat diet groups gained 80% more weight than the standard diet group. Eight of 12 mice in the W group, compared to only 1 of 12 mice in the WGSE group, had fasting blood glucose levels above 140 mg/dL. Mice in the WGSE group also had 21% lower fasting blood glucose and 17.1% lower C-reactive protein levels than mice in the W group (P < 0.05). However, the GSE supplementation did not affect oxidative stress in diet-induced obesity as determined by plasma oxygen radical absorbance capacity, glutathione peroxidase, and liver lipid peroxidation. Collectively, the results indicated a beneficial role of GSE supplementation for improving glycemic control and inflammation in diet-induced obesity.     

Two-year toxicity and carcinogenicity study of methyleugenol in F344/N rats and B6C3F(1) mice

Methyleugenol (MEG) was tested for toxicity/carcinogenicity in a 2-yr carcinogenesis bioassay because of its widespread use in a variety of foods, beverages, and cosmetics as well as its structural resemblance to the known carcinogen safrole. F344/N rats and B6C3F(1) mice (50 animals/sex/dose group) were given MEG suspended in 0.5% methylcellulose by gavage at doses of 37, 75, or 150 mg/kg/day for 2 yr. Control groups (60 rats/sex and 50 mice/sex) received only the vehicle. A stop-exposure group of 60 rats/sex received 300 mg/kg/day by gavage for 53 weeks followed by the vehicle only for the remaining 52 weeks of the study. A special study group (10 animals/sex/species/dose group) were used for toxicokinetic studies. All male rats given 150 and 300 mg/kg/day died before the end of the study; survival of female rats given 150 mg/kg/day and all treated female mice was decreased. Mean body weights of treated male and female rats and mice were decreased when compared to control. Area under the curve results indicated that greater than dose proportional increases in plasma MEG occurred for male 150 and 300 mg/kg/day group rats (6 and 12 month) and male 150 mg/kg/day mice (12 month). Target organs included the liver, glandular stomach, forestomach (female rats) and kidney, mammary gland, and subcutaneous tissue (male rats). Liver neoplasms occurred in all dose groups of rats and mice and included hepatoadenoma, hepatocarcinoma, hepatocholangioma (rats only), hepatocholangiocarcinoma, and hepatoblastoma (mice only). Nonneoplastic liver lesions included eosinophilic and mixed cell foci (rats only), hypertrophy, oval cell hyperplasia, cystic degeneration (rats only), and bile duct hyperplasia. Mice also exhibited necrosis, hematopoietic cell proliferation, and hemosiderin pigmentation. Glandular stomach lesions in rats and mice included benign and malignant neuroendocrine tumors, neuroendocrine cell hyperplasia, and atrophy and in mice included glandular ectasia/chronic active inflammation. In female rats, the forestomach showed a positive trend in the incidences of squamous cell papilloma or carcinoma (combined). Male rats also exhibited kidney (renal tubule hyperplasia, nephropathy, and adenomacarcinoma), mammary gland (fibroadenoma), and subcutaneous tissue (fibroma, fibrosarcoma) lesions. Male rats also exhibited malignant mesotheliomas and splenic fibrosis. These data demonstrate that MEG is a multisite, multispecies carcinogen.     

Reaction of fumonisin with glucose prevents promotion of hepatocarcinogenesis in female F344/N rats while maintaining normal hepatic sphinganine/sphingosine ratios

The reaction of the primary amine of fumonisin B(1) (FB(1)) with glucose was hypothesized to detoxify this mycotoxin. Eighty 10-day-old female F344/N rats were injected intraperitoneally with diethylnitrosamine (DEN; 15 mg/kg of body weight). At 4 weeks of age, the weaned rats were randomly assigned to one of four treatment groups with 20 rats each. At 9 weeks of age, four rats from each treatment group were killed. At 12 weeks, another five rats from each group were killed. At 20 weeks of age, the remaining rats were killed. In comparison with the rats fed basal diet or FB(1)-glucose (containing 25 ppm of FB(1)), rats fed 8 ppm (residual amount of free FB(1) in the FB(1)-glucose mixture) or 25 ppm of FB(1) had greater alanine aminotransferase activity at 9 and 20 weeks of age (P < 0.001), greater endogenous hepatic prostaglandin E(2) production at 20 weeks of age (P < 0.05), and significantly lower plasma cholesterol at 20 weeks of age (P < 0.01). Placental glutathione S-transferase (PGST)-positive and gamma-glutamyltransferase (GGT)-positive altered hepatic foci (AHF) occurred only in rats fed 25 ppm of FB(1) at 20 weeks of age. Hepatic natural killer (NK) cell activities were similar among the four groups, but the percentage of total liver-associated mononuclear cells exhibiting the NKR-P1(bright) marker was significantly greater in rats fed FB(1)-glucose, FB(1) (8 ppm) and FB(1) (25 ppm) than in control rats at 9 weeks of age, and FB(1)-glucose-treated rats had significantly lower NKR-P1(bright) cells as a percentage of total liver-associated mononuclear cells than rats fed 25 ppm of FB(1) at 20 weeks of age (P < 0.05). PGST- or GGT-positive AHF were not detected in any treatment group at 9 or 12 weeks of age. At 20 weeks of age, half of the rats fed 25 ppm of FB(1) had PGST- and GGT-positive AHF. The sphinganine (Sa) concentration and the Sa/sphingosine (So) ratio were significantly greater in the rats fed 25 ppm of FB(1) diet as compared with the control groups at, respectively, 12 or 20 weeks of age. Therefore, modifying FB(1) with glucose seems to prevent FB(1)-induced hepatotoxicity and promotion of hepatocarcinogenesis. The Sa/So ratio was not the most sensitive biomarker of FB(1) toxicity.     

Deoxynivalenol and zearalenone residues in eggs of laying hens fed with a naturally contaminated diet: effects on egg production and estimation of transmission rates from feed to eggs

The potential for the Fusarium mycotoxins 4-deoxynivalenol (DON) and zearalenone (ZON) to enter the human food chain through contaminated eggs was assessed using a controlled feed study. Four groups of laying hens (eight in each group) were fed a diet that included differing amounts of naturally contaminated wheat containing DON ( approximately 20 mg kg(-1)) and ZON (0.5 mg kg(-1)). Eggs were collected and pooled from each group on a daily basis. Pooled samples were analyzed by liquid chromatography with mass spectrometry detection (LC-MS/MS). The method allowed DON, other type B trichothecenes, ZON, and its metabolites to be determined in a single multi-residue analysis. The selectivity of the MS/MS procedure allowed cleanup to be minimized (for DON, cleanup by immunoaffinity column was used) or eliminated (for ZON). The limits of detection of 0.01 microg kg(-1) for DON and 0.1 microg kg(-1) for ZON in eggs were lower than previously published methods. None of the samples analyzed had detectable levels of ZON or its metabolites. Although maximum levels of DON contamination (10 mg kg(-1) feed) were relatively high, no adverse effects were observed on egg production. On the basis of the determined DON levels in the hen's diet and the determined levels of DON in the corresponding eggs, transmission rates of 15 000:1, 18 000:1, and 29 000:1 for treatment levels 5, 7.5, and 10 mg DON kg(-1) feed, respectively, were found. These results show that, although eggs could be a human exposure route for DON, the levels are insignificant compared to the other sources, although the presence of metabolites of DON was not studied.     

cry1Ac/cpti转基因大米水稻土中微生物群落的多样性研究

Two types of cry1Ac/cpti transgenic rice(GM1 and GM2)and their parental non-cry1Ac/cpti rice(CK1 and CK2)were planted in the field at Wufeng,Fujian Province,China for four years to investigate the influence of genetically modified rice on diversity of bacterial and fungal community in the paddy soil.The community composition and abundance of bacteria or fungi in the paddy soil were assessed at different growth stages of rice by denaturing gradient gel electrophoresis and real-time polymerase chain reaction based on 16S rRNA gene or SSU rRNA gene in the 4th year after the experimental establishment.The composition of bacterial or fungal community changed during rice growth,while no significant differences were observed between the fields cultivated with GM1and CK1,or between the fields cultivated with GM2 and CK2 in either bacterial or fungal community composition.The copy numbers of bacterial 16S rRNA gene in the soils with CK1,CK2,GM1 and GM2 ranged from 5.64×1011to 6.89×1011copies g-1dry soil at rice growth stages,and those of fungal SSU rRNA gene from 5.24×108to 8.68×108copies g-1dry soil.There were no marked differences in the copies of bacterial 16S rRNA gene or fungal SSU rRNA gene between CK1 and GM1 or between CK2 and GM2at any growth stage of rice.Planting cry1Ac/cpti transgenic rice had no significant effect on composition and abundance of bacterial and fungal community in paddy soil during the rice growing season at least in the short term.