High-cholesterol diets induce changes in lipid composition of rat erythrocyte membrane including decrease in cholesterol, increase in alpha-tocopherol and changes in fatty acids of phospholipids

Delayed Meal Timing, a Breakfast Skipping Model, Increased Hepatic Lipid Accumulation and Adipose Tissue Weight by Disintegrating Circadian Oscillation in Rats Fed a High-Cholesterol Diet

Background: To investigate whether shifted timing of eating, breakfast skipping, induces alterations in the circadian clock and abnormal lipid metabolism, we have established a delayed meal timing (DMT) protocol for rats, which started eating food 4 h delay. In the present study, control and DMT rats were fed a high-cholesterol diet during zeitgeber time (ZT) 12-24 and ZT 16-4, respectively. The DMT protocol increased the hepatic lipids and epididymal adipose tissue weight without changes in food intake and body weight. The surge in body temperature was delayed by 4 h in the DMT group, suggesting that energy expenditure was decreased in response to DMT. The peaks of the diurnal rhythm of serum non-esterified fatty acids and insulin were delayed by 2 and 4 h due to DMT, respectively. The oscillation peaks of hepatic de novo fatty acid synthesis gene expression was delayed by 4 h in response to DMT, whereas the peak of hepatic clock genes were 2 h delayed or not by DMT. Although metabolic oscillation is considered to be controlled by clock genes, the disintegration rhythms between the clock genes and lipid metabolism-related genes were not observed in rats fed a high-fat diet in our previous study. These data suggest that the circadian rhythm of de novo fatty acid metabolism is regulated by timing of eating, but is not directly controlled by clock genes. The present study suggests that breakfast skipping would complicate fatty liver and body fat accumulation.

Hepatoprotective Effect of Supercritical Carbon Dioxide Extracted Dabai Pulp Oil and Its Defatted Pulp

All food scientists must utilize plants for their application as functional foods to reduce hypercholesterolemia incidence through diet. Canarium odontophyllum (dabai) is a novel source for new healthy oil and functional foods. In this work, we evaluate the hepatoprotective effects of supercritical carbon dioxide (SC-CO₂) extracted dabai pulp oil (DPO) and defatted dabai pulp (DDP) against hypercholesterolemia elicited by a high-cholesterol diet in rats. Our results show that DPO and DDP supplementation exerted beneficial hypocholesterolemic effects against the high-cholesterol diet-fed rat. Nevertheless, supplementation with DDP revealed superior total cholesterol, low-density lipoprotein, and HMG-CoA reductase lowering efficacy (p < 0.05). Supplementation of either DPO or DDP did not significantly affect AST and ALT levels than normal rats (p > 0.05). Therefore, DDP and DPO are considered as having no toxicological significance. The histological section of rats treated with DPO and DDP showed improved steatosis in hepatocytes. HPLC analysis revealed that DPO and DDP contained syringic acid, which plays an important role in the beneficial effect. In conclusion, our results support the hypocholesterolemic and hepatoprotective effects of DPO and DDP in the hypercholesterolemic rats model.

Quality of Dabai Pulp Oil Extracted by Supercritical Carbon Dioxide and Supplementation in Hypercholesterolemic Rat-A New Alternative Fat

Dabai pulp oil (DPO) is new oil extracted from the pulp of Canarium odontophyllum. The quality and efficacy of DPO are needed to promote its potential as a new alternative fat. Therefore, we investigate the quality of DPO, which includes moisture and volatile content (MVC), free fatty acid content (FFA), iodine value (IV), and peroxide value (PV). Furthermore, we evaluate the efficacy of DPO against hypercholesterolemia elicited by a high-cholesterol diet in rats. The MVC of DPO was <0.001 ± 0.00%. Next, the FFA in DPO was 2.57 ± 0.03%, and the IV of DPO was 53.74 ± 0.08 g iodine/100 g oil. Meanwhile, the PV of DPO was 4.97 ± 0.00 mEq/kg. Supplementation of DPO in hypercholesterolemic rats for 30 days revealed the hypocholesterolemic effect (significant reduction of total cholesterol, triglyceride, and 3-hydroxy-3-methylglutaryl-CoA reductase) accompanied by a significant reduction of inflammatory markers (C-reactive protein, interleukin-6 and tumour necrosis factor-α), and lipid peroxidation (MDA). We also observed a significant improvement of lipoprotein lipase (LPL) and antioxidant capacities (total antioxidant status, superoxide dismutase, glutathione peroxidase, and catalase) of the rats. The results on the quality and efficacy of locally made DPO suggest its potential use as a healthy alternative fat in the future.

Effect of Defatted Dabai Pulp Extract in Urine Metabolomics of Hypercholesterolemic Rats

A source of functional food can be utilized from a source that might otherwise be considered waste. This study investigates the hypocholesterolemic effect of defatted dabai pulp (DDP) from supercritical carbon dioxide extraction and the metabolic alterations associated with the therapeutic effects of DDP using ¹H NMR urinary metabolomic analysis. Male-specific pathogen-free Sprague-Dawley rats were fed with a high cholesterol diet for 30 days to induce hypercholesterolemia. Later, the rats were administered with a 2% DDP treatment diet for another 30 days. Supplementation with the 2% DDP treatment diet significantly reduced the level of total cholesterol (TC), triglyceride, low-density lipoprotein (LDL), and inflammatory markers (C-reactive protein (CRP), interleukin 6 (IL6) and tumour necrosis factor-α (α-TNF)) and significantly increased the level of antioxidant profile (total antioxidant status (TAS), superoxide dismutase (SOD), glutathione peroxide (GPX), and catalase (CAT)) compared with the positive control group (PG) group (p < 0.05). The presence of high dietary fibre (28.73 ± 1.82 g/100 g) and phenolic compounds (syringic acid, 4-hydroxybenzoic acid and gallic acid) are potential factors contributing to the beneficial effect. Assessment of ¹H NMR urinary metabolomics revealed that supplementation of 2% of DDP can partially recover the dysfunction in the metabolism induced by hypercholesterolemia via choline metabolism. ¹H-NMR-based metabolomic analysis of urine from hypercholesterolemic rats in this study uncovered the therapeutic effect of DDP to combat hypercholesterolemia.

Dietary Supplementation with Hazelnut Oil Reduces Serum Hyperlipidemia and Ameliorates the Progression of Nonalcoholic Fatty Liver Disease in Hamsters Fed a High-Cholesterol Diet

Objective: Hazelnut oil (HO) is rich in monounsaturated fatty acids and polyunsaturated fatty acids. This study intended to analyze the effects of hazelnut oil supplementation on the serum lipid profile and nonalcoholic fatty liver disease in hamsters fed a high-cholesterol (HC) diet. Methods: Hamsters were fed a basic diet (control group) and an HC diet (HC group) for 16 weeks (n = 10 in each group). Hamsters were fed an HC diet for four weeks to induce hyperlipidemia and were then fed an HC diet enriched with 5% (low-dose HC + HO group; n = 10) and 10% HO (high-dose HC + HO group; n = 10) for 12 weeks. Serum lipid levels, hepatic changes (including steatosis, inflammation, and fibrosis), and hepatic prooxidant-antioxidant status (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione S-transferase (GST)) were evaluated after the treatment period. Results: Hamsters in the control group showed normal serum lipid profiles, normal liver function, and moderate glycogen storage without hepatic steatosis. Hamsters in the HC group showed severe hyperlipidemia, severe hepatic steatosis, and moderate steatohepatitis (mononuclear cell and neutrophil infiltration, oval cell hyperplasia, and fibrosis). Compared to the HC group, both the low-dose and the high-dose HC + HO groups showed a significant reduction of hyperlipidemia (serum triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and very-low-density lipoprotein cholesterol (VLDL-C levels)) and improved liver function (serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT)). Additionally, compared to the HC group, intrahepatic triglyceride accumulation (IHTC) was significantly higher in the HC + HO group, while the incidence of steatohepatitis was significantly lower. The intake of the HC diet was associated with a higher level of lipid peroxidation (malondialdehyde, MDA) and a lower concentration of hepatic antioxidant enzymes (SOD, GPx, and GST), and all these factors were partially improved in the low-dose and high-dose HC + HO groups. Conclusions: Our findings indicate that the intake of HO reduced serum hyperlipidemia and oxidative stress and ameliorated the progression of nonalcoholic fatty liver disease in hamsters fed a high-cholesterol diet.

Semi-synthetic diet versus diet using natural ingredients-Comparative study in female Golden Syrian hamsters

Semi-synthetic diets (SSD) are recommended and are widely used to carry out experiments in rodents. However, in our experiments planned to carry out generation studies in female Golden Syrian hamsters using semi-synthetic diets, it was observed that the hamsters did not conceive as a result of decreased food intake. In this paper, we present the effects of both semi-synthetic diets and natural source diets (NSD) on food intake, body weight and reproductive performance of this species. Four-week-old female hamsters were equally divided into 3 groups and initially acclimatized for 2 weeks on natural chow diet (NCD). Thereafter, they were fed either control diet, high fat diet (HFD) or low protein diet (LPD) based on semi-synthetic/natural source ingredients until 12 weeks. Daily food intake and weekly body weights were monitored. Hamsters were kept for mating for about 2 weeks from 10th week onwards, during which the pregnancy confirmation test was done using standard vaginal smear examination. In all the groups fed SSD, the food intake was very poor, hamsters lost body weight and did not conceive, thus preventing us from carrying out further experiments. Hamsters fed NCD/NSD ingested more than twice as much as hamsters fed SSD (7-8 g/day/hamster against 3 g/day/hamster on average respectively). Based on the results of the current research, we conclude that the routinely used semi-synthetic diet is not suitable for carrying out studies in female hamsters. We suggest that scientists must also consider the unusual biological characteristics of a given species besides other biological factors. It is therefore critical to select appropriate biological models and diets that provide optimal sensitivity and specificity to accomplish the research objectives.

Beneficial Effect of Supercritical Carbon Dioxide Extracted (SC-CO2) Dabai (Canarium odontophyllum) Pulp Oil in Hypercholesterolemia-Induced SPF Sprague-Dawley Rats

Production of dabai ( Canarium odontophyllum) pulp oil by supercritical carbon dioxide extraction is still relatively new and should be investigated. The objective of this study was to investigate the effects of supercritical carbon dioxide (SC-CO2) extracted dabai pulp oil (DPO) on rats induced with hypercholesterolemia. Male-specific pathogen free (SPF) Sprague-Dawley rats were fed with diets with high cholesterol contents for 4 weeks to induce hypercholesterolemia. Afterwards, the hypercholesterolemia rats were divided into groups namely: positive control group (PG), low dose group (LG), high dose group (HG), and statin group (SG). 0.5% and 2% of SC-CO2 DPO were administered to the LG and HG groups respectively for another 4 weeks. Changes in body weight and biochemistry profiles were measured. When compared with the normal rats that were fed with a normal basal diet, the hypercholesterolemia rats had elevated body weights and major increments in total cholesterol and LDL levels(NG) ( p<0.05). Paired-samples t-tests showed that the LG group exhibited a notable reduction in total cholesterol, triglyceride and LDL levels ( p<0.05) and an 8.26% increment in HDL level. Meanwhile, diminishing levels of total cholesterol, triglyceride and LDL levels were found in the HG group. Notable differences in AST and ALT levels were not detected in LG and HG groups when compared with the NG group. These results indicated that SC-CO2dabai pulp oil contains vital elements which contribute to cholesterol-loweringeffects and which can be used as special oils for health promotion and disease prevention.

Effect of dietary supplementation with olive and sunflower oils on lipid profile and liver histology in rats fed high cholesterol diet

OBJECTIVE

To compare the effects of high-monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) against the metabolic disorders elicited by a high-cholesterol diet (HC) in rats.

METHODS

Using in vivo dietary manipulation, rats were fed with different diets containing 4% soybean oil (cholesterol free diet) and 1% HC containing 12% olive oil (HC + OO) enriched with MUFA and 12% sunflower oil (HC + SO) enriched with PUFA for 60 d. Serum lipid levels and hepatic steatosis were evaluated after the treatment period.

RESULTS

Comparatively, rats treated with HC + OO diet experienced a decrease in the serum LDL-C, VLDL-C and CT levels compared to those fed with HC + SO diet (P < 0.05). Otherwise, HC + OO provoked significant microvesicular steatosis situated in the hepatic acinar zone 1.

CONCLUSIONS

HC + OO diet has high absorption velocity in the acinar zone 1 of liver compared to the HC + SO diet. Based on this, the reduction of the LDL-C, VLDL-C and CT serum levels in the animals treated with HC + OO diet may have been caused by the delay in the FA release to the blood.

High dietary fat and cholesterol exacerbates chronic vitamin C deficiency in guinea pigs

Vitamin C deficiency – or hypovitaminosis C defined as a plasma concentration below 23 μm – is estimated to affect hundreds of millions of people in the Western world, in particular subpopulations of low socio-economic status that tend to eat diets of poor nutritional value. Recent studies by us have shown that vitamin C deficiency may result in impaired brain development. Thus, the aim of the present study was to investigate if a poor diet high in fat and cholesterol affects the vitamin C status of guinea pigs kept on either sufficient or deficient levels of dietary ascorbate (Asc) for up to 6 months with particular emphasis on the brain. The present results show that a high-fat and cholesterol diet significantly decreased the vitamin C concentrations in the brain, irrespective of the vitamin C status of the animal (P < 0·001). The brain Asc oxidation ratio only depended on vitamin C status (P < 0·0001) and not on the dietary lipid content. In plasma, the levels of Asc significantly decreased when vitamin C in the diet was low or when the fat/cholesterol content was high (P < 0·0001 for both). The Asc oxidation ratio increased both with low vitamin C and with high fat and cholesterol content (P < 0·0001 for both). We show here for the first time that vitamin C homoeostasis of brain is affected by a diet rich in fat and cholesterol. The present findings suggest that this type of diet increases the turnover of Asc; hence, individuals consuming high-lipid diets may be at increased risk of vitamin C deficiency.

High-cholesterol diet increases xanthine oxidase and decreases nitric oxide synthase activities in erythrocytes from rats

The aim of this study was to investigate the effects of a high-cholesterol diet on oxidant/antioxidant status and nitric oxide synthase (NOS) activity in erythrocytes from rats. Sixteen Sprague-Dawley-type albino male rats were used in the study. The rats were randomly divided into 2 groups: the control group (group 1) was fed a standard rat diet, and the treated group (group 2) was fed a high-cholesterol diet (4% cholesterol, 1% cholic acid, and 0.5% thiouracil) in addition to standard pellet rat diet for 3 months. At the end of the study period, blood samples were obtained from the rats under ether anesthesia. Oxidant (malondialdehyde level, sensitivity to oxidation value, and xanthine oxidase [XO] activity) and antioxidant parameters (antioxidant potential value, superoxide dismutase, catalase, and glutathione peroxidase activities) were studied in erythrocyte preparations. Activities of erythrocyte NOS and arginase enzymes and serum total cholesterol levels were also measured. We observed that serum total cholesterol levels, erythrocyte XO activities, and sensitivity to oxidation values significantly increased in group 2 (cholesterol fed) compared with the control group (group 1). Erythrocyte NOS activities were also found to decrease in group 2. In conclusion, our results suggest that cholesterol feeding causes an increase in XO activity and a decrease in NOS activity in the erythrocytes from rats. The increase in XO activity may render the erythrocyte membranes sensitive to oxidant stress, and the decrease in NOS activity in the erythrocytes may increase cardiovascular disease risk via reduced endothelial relaxation.

eNOS T-786C polymorphism affects atorvastatin-induced changes in erythrocyte membrane fluidity

PURPOSE

Statins have pleiotropic effects, including endothelial nitric oxide synthase (eNOS) upregulation and increased nitric oxide formation, which can be modulated by a genetic polymorphism in the promoter region of the eNOS gene (T-786C). Here, we report our investigation of whether this polymorphism modulates the effects of atorvastatin on the fluidity of erythrocyte membranes.

METHODS

We genotyped 200 healthy subjects (males, 18-60 years of age) and then randomly selected 15 of these with the TT genotype and 15 with the CC genotype to receive placebo or atorvastatin (10 mg/day oral administration) for 14 days. Cell membrane fluidity was evaluated by electron paramagnetic resonance (EPR) and spin-labeling method. The EPR spectra were registered on a VARIAN-E4 spectrometer. Thiobarbituric acid-reactive species (TBA-RS) and plasma membrane cholesterol were determined in the erythrocytes.

RESULTS

Atorvastatin reduced membrane fluidity in CC subjects (P < 0.05) but not in those with the TT genotype (P > 0.05). While no significant differences were found in plasma membrane cholesterol concentrations, higher TBA-RS concentrations were found in the CC subjects than in the TT subjects (P < 0.05).

CONCLUSIONS

These findings suggest that a short treatment with atorvastatin is disadvantageous to subjects with the CC genotype for the T-786C polymorphism compared to those with TT genotype, at least in terms of the hemorheological properties of erythrocytes.

Effects of a high-cholesterol diet on cell behavior in rat periodontitis

Studies have shown an association between periodontitis and serum cholesterol levels. We hypothesized that high dietary cholesterol could influence periodontitis as a result of proliferation of the junctional epithelium. Rats were divided into 4 groups. Two groups were fed a regular diet, and 2 groups were fed a high-cholesterol diet. One of each dietary group was treated with periodontitis-inducing agents (lipopolysaccharide and proteases), while the other was treated with pyrogen-free water. Feeding rats with a high-cholesterol diet induced an increase in blood total cholesterol and a decrease in high-density lipoprotein cholesterol. Proliferation of the junctional epithelium with increasing bone resorption was promoted by the consumption of a high-cholesterol diet. High dietary cholesterol further increased the cell-proliferative activity of the junctional epithelium induced by lipopolysaccharide and proteases. These results suggest that high dietary cholesterol can initiate and augment periodontitis in the rat periodontitis model.

Absence of correlation between glycated hemoglobin and lipid composition of erythrocyte membrane in type 2 diabetic patients

Correlation of glycated hemoglobin (HbA(1c)) level with degrees of certain peroxidative changes in erythrocyte membrane lipids in diabetic patients have been reported. In the present study, peroxidation of erythrocyte lipids was assessed by changes in tocopherols (Toc), phospholipids (PL), and malondialdehyde (MDA). Membrane cholesterol, Toc, and PL were determined from the same lipid extract. Toc and cholesterol were measured simultaneously by high-performance liquid chromatography (HPLC), and each PL class was determined by a single HPLC elution with ultraviolet light (UV) detection. The detection of PL with UV depends primarily on double bonds in fatty acids and shows a decrease in fatty acids by peroxidation. Changes in Toc and each PL were calculated on the basis of cholesterol and SM, respectively, since cholesterol and sphingomyelin (SM) in the cell membrane are not prone to peroxidation. MDA was measured by an HPLC method with fluorescence detection. These methods for assessment for peroxidation of membrane lipids in intact erythrocytes were validated by experiments with 2, 2-azobis(2-amidinopropane)dihydrochloride (AAPH) and tert-butylhydroperoxide (tBHP); nevertheless, significant differences in the levels of Toc, each PL class, and MDA between a high-HbA(1c) group and a low-HbA(1c) group were not detected.