Rat Plasma Lipoproteins Research Articles

Dietary Grape Seed Tannins Affect Lipoproteins, Lipoprotein Lipases and Tissue Lipids in Rats Fed Hypercholesterolemic Diets , ,

The effects of monomeric and polymeric grape seed tannins on rat plasma lipoproteins, lipoprotein lipase, hepatic lipase and aortic and hepatic lipid concentration were studied. Male Sprague-Dawley rats received either a normal diet (with no added cholesterol and no tannins), a control diet (hypercholesterolemic diet) or hypercholesterolemic diets supplemented with 2% tannin monomers or 2% polymers 3 or 9 wk. Plasma total cholesterol, triacylglycerol, LDL cholesterol and VLDL concentrations were significantly higher and the HDL cholesterol concentration lower in controls and in rats fed the diet supplemented with monomers compared with rats fed polymeric tannins at both time points. Lipoprotein lipase and hepatic lipase activities were significantly higher in control and in monomer-fed groups than in the polymer-fed group. Hepatic and aortic cholesterol and triacylglycerol concentrations were significantly higher in control rats and those fed monomers than in the polymer-fed group. Moreover, plasma HDL cholesterol and hepatic lipase activity were closely associated with low aortic cholesterol and triacylglycerol in rats fed polymeric tannins. These rats also exhibited greater fecal excretion of cholesterol and especially bile acids than the control or monomer-fed groups. Thus dietary grape seed tannins have a pronounced anti-hypercholesterolemic effect by enhancing reverse cholesterol transport and also by reducing intestinal cholesterol absorption and increasing bile acid excretion.

Modulatory effect of Jatropha gossypifolia leaf on testicular lipidomics and plasma lipoproteins of rats exposed to cypermethrin

The use of pesticides such as cypermethrin (Cyp) has become hazardous resulting into public and environmental health issues in the world with several studies pointing to a decline in reproductive health coupled with increased risk of infertility. Thus, pesticide safety and effects on human exposure in relation to general and reproductive health are of paramount concern. This study was aimed at investigating the biochemical alterations in the lipidomics of plasma components and reproductive organ of male rats exposed to cypermethrin. The animals were grouped into eight comprising seven animals each and orally treated for 28 days: control, 20 mg/kg body weight of Cyp, Cyp+JG(50 mg/kg), Cyp+JG(100 mg/kg), Cyp+ALA(50 mg/kg), JG(50 mg/kg), JG(100 mg/kg) and ALA(50 mg/kg). Lipid profile analyses were carried out on the plasma, HDL, vLDL+LDL, and testis homogenate of the rats as described by the diagnostic kit manual. Results obtained from this study showed that cypermethrin administration significantly elevated triglyceride (105.22%) and not significant cholesterol level (15.28%) in the plasma; significantly increased testicular triglyceride (96.46%) and cholesterol (64.99%) concentrations; significantly decreased HDL triglyceride (46.57%) and cholesterol (38.37%); significantly increased the concentration of vLDL+LDL triglyceride (126.28 %) and cholesterol (76.09%) in comparison with the control. Co-administration with both doses of J. gossypifolia (JG) leaf extract and alpha-lipoic acid (ALA) significantly reversed these alterations. Thus, the phytoconstituents of Jatropha gossypifolia plant extract possesses modulatory potentials that can mitigate the effect of cypermethrin on the reproductive organ and plasma lipidomics especially in the treatment of heart related disorders caused by hyperlipidemia.

Plasma Lipoproteins as a Transport Form of Extracellular DNA

We showed DNA-binding activity of different classes of plasma lipoproteins in rats and humans. Experiments with fluorescent dye Hoechst 33258 showed that about 12% extracellular plasma DNA is present in circulating lipoproteins complexes; 7-8% of them with HDL. Structural HDL protein apoA-I probably plays the major role in the interaction between extracellular DNA and lipoprotein particle. Participation of lipoproteins in the transport of extracellular DNA can be considered as an important mechanism for elimination of nucleic acids from blood plasma.

Differing Effect of Protein Isolates from Different Cultivars of Blue Lupin on Plasma Lipoproteins of Hypercholesterolemic Rats

Protein from white lupin is capable of lowering plasma lipids. We investigated in this study the effect of total protein extracts (TPEs) from different cultivars of blue lupin (Probor, Vitabor and Boregine) and alpha-/beta-conglutin from Boregine on the plasma lipids of rats. Rats were fed on a hypercholesterolemic diet containing either lupin protein (50 g/kg) or casein (50 g/kg) for 17 d. The rats fed with TPE from Vitabor and alpha-/beta-conglutin had lower triglyceride concentrations in the plasma (-24% and -21%, respectively) and very-low-density lipoprotein (VLDL; -40% and -29%, respectively) than the rats fed with casein. TPE from Vitabor was also capable of lowering low-density lipoprotein (LDL) cholesterol (-37%). In the liver of the rats fed with TPE from Vitabor, the expression of the genes involved in triglyceride and cholesterol synthesis was down-regulated. This study shows that the Vitabor cultivar of blue lupin had the most beneficial effect on plasma lipids which was presumed to have been caused by the down-regulation of genes involved in lipid synthesis.

Efficacy of Ganoderma lucidum on plasma lipids and lipoproteins in rats fed with high cholesterol diet

PurposeThe purpose of this paper is to report on the anti‐cholesterol activities of Ganoderma lucidum on Sprague–Dawley white rats.Design/methodology/approachRats were divided into four groups with a sample size of six rats per groups. Different formula diets were given to each group for a period of six months. At regular intervals, blood samples were taken and analysed for the total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL‐C) and low density lipoprotein (LDL‐C) levels.FindingsAdministration of hyperlipidemia diet in rats fed with 1 per cent cholesterol diet caused an increase in the TC, TG, as well as LDL‐C level as compared to the control. A decrease of 23.6 per cent in the HDL‐C level was also noted. However, supplementation of the feed with G. lucidum (0.1 per cent) in rats decreased the TC, TG and LDL‐C level significantly (P < 0.05) while further increased the plasma concentration of HDL‐C. In the case of rats fed with diet containing a mixture of 1 per cent cholesterol and 0.1 per cent of Ganoderma, the lipid profile showed much higher readings (p < 0.05) compared to the chol group.Practical implicationsThe possible efficacy of G. lucidum in reducing the deposition of cholesterol in the wall of the blood vessels was indicated.Originality/valueThis article provides useful information to health care providers and consumers.

Diallyl tetrasulfide protects cadmium-induced alterations in lipids and plasma lipoproteins in rats.

Lipoprotein abnormalities disrupt the levels of serum and cellular lipid, which accounts for the genesis of cardiovascular diseases. Cadmium (Cd) exposure is associated with a number of distinct pathological changes including dyslipidemia. Garlic and its organosulfur compounds seem to hold promise in reducing the risk factors associated with cardiovascular disease. The present study was undertaken to assess the effect of diallyl tetrasulfide (DTS) from garlic on Cd-induced alterations in the levels of lipids and lipoproteins in Wistar rats. Subcutaneous administration of Cd (3 mg/[kg body weight d]) for 3 weeks showed a significant (P < .05) increase in total cholesterol, very low density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, free fatty acids, and phospholipids, with a significant (P < .05) reduction in high-density lipoprotein cholesterol in plasma. In addition, the activity of hydroxy-3-methylglutaryl-coenzyme A reductase and the levels of cholesterol, free fatty acids, and triglycerides were significantly (P < .05) increased and the level of phospholipids was significantly decreased (P < .05) in liver of Cd-treated rats. Oral administration ofDTS (40 mg/[kg body weight d]) significantly (P < .05) reduced the levels of cholesterol, free fatty acids, triglycerides, very low density lipoprotein cholesterol, and low-density lipoprotein cholesterol; but the activity of hepatic hydroxy-3-methylglutaryl-coenzyme A reductase and the levels of high-density lipoprotein cholesterol increased (P < .05) in Cd-treated rats. Our results indicate that the administration of DTS afforded remarkable protection against Cd-induced alterations in lipid metabolism and thereby reduced the Cd-mediated cardiovascular diseases.

Changes in plasma lipids after a non-lethal dose of cycloheximide in rats.

This paper describes a study of the effect of a single intraperitoneal non-lethal dose of cycloheximide (CHM; 2.0 mg/kg body weight) on the concentration of plasma lipids and lipoproteins in male rats killed one, two, three, four and nine days after receiving the dose. The concentration of triglycerides, total cholesterol, high-density lipoproteins (HDL)-cholesterol and low-density lipoproteins (LDL)-cholesterol was measured in treated and control animals. The effect of CHM on the concentration of triglycerides, total cholesterol, HDL-cholesterol, and LDL-cholesterol was visible in rat plasma throughout the study. Total cholesterol and HDL-cholesterol concentrations showed the same pattern of changes, probably due to the reversible inhibition of apolipoprotein apo A-I synthesis by CHM. The concentration of triglycerides decreased after a lag period of three days when the reserves of apolipoprotein apo B, the main apolipoprotein of very low-density lipoproteins (VLDL)-cholesterols produced in the liver, were consumed.

Ultracentrifugation Micromethod for Preparation of Small Experimental Animal Lipoproteins

Sequential flotation ultracentrifugation is commonly used in the preparation of plasma lipoproteins. However, protocols often require prolonged centrifugation time (48–72 h) and large plasma volumes (2–20 ml), which makes them unsuitable for studies on small laboratory animals. Although analytical techniques such as FPLC have often small sample requirements, further fraction analysis is often limited to the small fraction volume obtained. A sequential ultracentrifugation micromethod is described to obtain rat lipoprotein fractions from 400 μl of plasma in a cumulative centrifugation time of 7.5 h. Fraction volumes were determined and densities were adjusted to those of rat plasma lipoproteins. Polyacrylamide gel electrophoresis and enzymatic measurements of triglycerides, total cholesterol, and phospholipids were used to assess the purity of the lipoprotein fractions. The results were compared with those obtained from a classical sequential ultracentrifugation protocol. The micromethod presented here can be further adapted to other experimental animal species with little modifications.

The stereoselective distribution of halofantrine enantiomers within human, dog, and rat plasma lipoproteins.

To study the in vitro distribution of the enantiomers of the antimalarial drug halofantrine in human, dog and rat plasma lipoprotein-fractions. Plasma was spiked with racemic halofantrine (1,000 ng/ml) and incubated for 1 h at 37 degree C. The fractions (high and low density lipoproteins, triglyceride-rich lipoproteins and lipoprotein deficient plasma) were separated using density gradient ultracentrifugation. Fractions were assayed for halofantrine enantiomer using stereospecific high performance liquid chromatography. The (-) enantiomer of halofantrine displayed higher affinity for the lipoprotein-deficient fraction than the (+) enantiomer in all three species. The (+) enantiomer was predominately located in the lipoprotein rich fractions of dog and human plasma (the (+):(-) ratio ranging from 1.2-9.6). In contrast, the (+):(-) ratio was consistently < 1 in lipoprotein-deficient fractions. Dog displayed a large magnitude of stereoselectivity in halofantrine distribution to the plasma fractions tested. There were substantial interspecies differences in the pattern of distribution of halofantrine enantiomers within the different fractions. A significant positive relationship was observed between halofantrine uptake into lipoprotein-rich fractions and the percent of apolar core lipid in those fractions. There was also a strong negative correlation between total protein concentration and the enantiomeric ratio in the lipoprotein-deficient plasma fraction. Distribution of halofantrine enantiomer to plasma lipoprotein-fractions is stereoselective and species specific. This differential binding of halofantrine enantiomers to lipoproteins may need to be considered in viewing pharmacokinetic and pharmacodynamic data involving the drug.

Distribution of oleoyl-estrone in rat plasma lipoproteins.

Pooled adult normal rat plasma was used for the separation of lipoprotein fractions: VLDL, LDL and HDL, from which a total lipids extract was obtained. The presence of fragments with the MW of estrone and oleoyl-estrone in the lipoprotein fractions was analyzed by HPLC-MS. The results show that oleoyl-estrone is the major estrone component in lipoproteins; this molecular species was present in all three lipoprotein lipid extracts. The lipoprotein fractions were used for the analysis of protein and lipid classes: triacylglycerols, total and esterified cholesterol and phospholipids as well as acyl-estrone. About half of the total acyl-estrone was in the HDL fraction and only about 10% in the VLDL fraction. HDLs contained about one molecule in 50 particles, LDLs one molecule per particle and VLDLs 15 molecules per particle, i.e. given their size, the larger lipoproteins contained more oleoyl-estrone than the HDLs. The distribution of this hormone suggests that oleoyl-estrone is lost with other lipids as the lipoproteins shrink. The results presented show that oleoyl-estrone is a molecule found naturally in rat lipoproteins in low concentrations - the lowest in HDLs - that are consistent with its postulated role in the control of body weight.

The Action of Higher Basidiomycetes Mushrooms Mycelia on Plasma Lipids and Lipoproteins of Hyperlipidemic Rats and Guinea Pigs

The Action of Higher Basidiomycetes Mushrooms Mycelia on Plasma Lipids and Lipoproteins of Hyperlipidemic Rats and Guinea Pigs

Anion-exchange high-performance liquid chromatographic assay of plasma lipoproteins of rabbits, rats and mice

A fast, accurate and precise high-performance liquid chromatographic assay method has been developed for plasma lipoproteins of experimental animals, rabbits, rats and mice. The method includes complete separation of high, low and very low density lipoproteins from one another within 20 min by a DEAE–glucomannan gel using stepwise elution, and determination by postcolumn reaction with an enzymatic cholesterol reagent as the total cholesterol level. The relative standard deviation of each lipoprotein assay was highly reproducible, being less than 2.0 and 2.4% for repeatability and intermediate precision, respectively. The method was successfully applied to the assays of plasma lipoproteins in three species of normolipidemic and hyperlipidemic animals.

Effects of Ionizing Radiation (Neutrons/Gamma Rays) on Plasma Lipids and Lipoproteins in Rats

Male Wistar rats weighing 250 g were exposed to 4 Gy of neutrons/gamma radiation (3.33 Gy of neutrons and 0.66 Gy of gamma rays). After whole-body irradiation, plasma cholesterol and phospholipid levels increased up to 62 and 37%, respectively, at day 4 and then returned to control values 12 days after irradiation. Plasma triglyceride concentrations decreased concomitantly with decreased food intake after irradiation but remained higher than in pair-fed control rats. Plasma lipoproteins were separated by ultracentrifugation on a density gradient (1.006-1.210 g/ml). Four days after irradiation, most of the cholesterol (62% compared to 31% in controls, P < 0.001) is transported by apolipoprotein E-rich high-density lipoproteins. At the same time, plasma levels of apolipoproteins B and E were increased by 28 and 65%, respectively, while those of apolipoproteins AI and AIV were reduced by 21 and 59%, respectively. While in the liver of irradiated rats the apolipoprotein B/E receptor number was not modified, the hydroxymethylglutaryl coenzyme A reductase activity was fivefold higher than in control pair-fed rats. Four days after irradiation, the susceptibility of lipoproteins to peroxidation, as measured by the formation of conjugated dienes in the presence of Cu2+, was markedly increased while plasma vitamin E levels were decreased, demonstrating that irradiation reduces antioxidant stores markedly. These results suggest that such modified lipoproteins could be involved in radiation-induced vascular damage.

Vasoactive mediators affect the clearance of lipids from emulsion models of plasma lipoproteins in rats.

We wished to establish whether the haemodynamic changes accompanying alterations in blood pressure exert a direct effect on clearance of chylomicron-like emulsions. N-Nitro-L-arginine (NOLA) and endothelin-1 were used to increase the blood pressure of normotensive rats, sodium nitroprusside (NP) and calcitonin gene-related peptide (CGRP) were used to decrease the blood pressure of spontaneously hypertensive rats (SHR). The lipid emulsions contained radiolabeled triolein (TO) and cholesteryl oleate (CO) to trace plasma clearances. NP and CGRP enhanced TO clearance in the SHR but slowed the rate of CO clearance. NOLA in normotensive rats clearly slowed the rate of TO removal and also retarded CO clearance, whereas with endothelin-1 TO clearance remained unaffected and CO removal was markedly slowed. The effects on TO clearance are consistent with changes in arteriolar resistance regulating access of emulsion particles to lipoprotein lipase on the endothelial cells of capillaries in muscle and adipose tissue. The changes in CO removal rate are more difficult to interpret because factors determining hepatic blood flow are complex. The results suggest that haemodynamic changes potentially affect circulation times of various lipoprotein species in the plasma, with probable consequences in relation to atherogenesis.

Lipase activities in post-heparin plasma and tissues, and susceptibilities of lipoproteins in experimental diabetic rats.

Heparin administration to diabetic rats caused no change in VLDL, an increase in IDL and a decrease in LDL on electrophoretic analysis of plasma lipoproteins, while the administration to control rats markedly decreased VLDL and increased IDL and LDL. Both hepatic triglyceride lipase (HTGL) and lipoprotein lipase (LPL) activities in the postheparin plasma were lower in the diabetic rats than in the controls, and the reduction of HTGL activity was greater than that of LPL activity in the diabetic rats. The LPL activity in the adipose tissue was lower in the diabetic rats than in the controls, but the activities in the cardiac and skeletal muscles were similar in the two rats. The HTGL-catalyzed fatty acid (FA) releases from the diabetic VLDL and IDL were lower than those from the normal rat VLDL and IDL, while the LPL-catalyzed FA release in the diabetic rats was not different from those in the controls. The decreases in LPL and HTGL activities and the markedly impaired susceptibility of IDL to HTGL coincide well with the postheparin changes in plasma lipoproteins in diabetic rats, an increase in IDL and a decrease in LDL.

Long-term effects of antihypertensive treatment and good glycemic control on plasma lipids in diabetic rats

The long-term effects of angiotensin-converting enzyme inhibitors (captopril and enalapril), calcium-entry blockers (diltiazem and nicardipine), and good glycemic control on plasma lipids and lipoproteins were studied in streptozotocin diabetic rats. Diabetic rats had increased plasma cholesterol, tryiglycerides, very-low-density lipoprotein (VLDL), and low-density lipoprotein (LDL) cholesterol, and decreased levels of high-density lipoprotein (HDL) cholesterol than in normal rats. Compared to other antihypertensives, nicardipine seems to have a less beneficial effect on lipids and lipoproteins. However, it is only the good glycemic control that normalized these plasma lipids and lipoproteins in diabetic rats. This suggests that good glycemic control prevents dyslipidemia in diabetic rats. The observed beneficial effects of antihypertensives were unrelated to either food or water intake.

Magnesium deficiency modulates hepatic lipogenesis and apolipoprotein gene expression in the rat

The present study was performed to determine the effects of magnesium (Mg) deficiency upon plasma lipoproteins and hepatic apolipoprotein gene expression in the rat. The most obvious effect of Mg-deficiency on plasma lipids is a marked increase in post-prandial triacylglycerol concentration. This increased triglyceridemia persists in fasted rats. Density gradient ultracentrifugation analysis revealed marked alterations in the distribution of plasma lipoproteins in Mg-deficient rats. An increase in triacylglycerol-rich lipoproteins (TGRLP) was associated with a significant increase in plasma apolipoprotein B (apo B) concentration and was accompanied by selective accumulation of apo B-48. A decrease in high-density lipoproteins (HDL) was accompanied by a corresponding decrease in plasma apo E concentration and a concordant decrease in hepatic apo E mRNA abundance and biosynthesis. Hepatic apo B-100 synthesis was reduced by over 75% in Mg-deficient animals despite an increase in hepatic apo B mRNA abundance. However, this change in hepatic apo B gene expression was not associated with alterations in posttranscriptional apo B mRNA editing. These changes in apolipoprotein gene expression were associated with increased hepatic lipogenesis, despite the observation that net triacylglycerol secretion rates were not different between Mg-deficient and control animals. Taken together, the data demonstrate a complex pattern of alterations in hepatic lipid metabolism and apolipoprotein gene expression in the Mg-deficient rat and suggest a defect in the catabolism rather than secretion of TGRRP as the major factor underlying the altered plasma lipoprotein profile.

Effects of a fish oil-lard diet on rat plasma lipoproteins, liver FAS, and lipolytic enzymes.

The effects of a fish oil concentrate on blood lipids and lipoproteins were examined in relation to their effects on liver fatty acid synthase (FAS), 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, adipose tissue lipoprotein lipase (LPL), and hepatic triglyceride lipase (H-TGL). For 15 days, 2-mo-old rats were fed a control diet (10% of calories from fat, 4% fat by weight) or diets with 50% of calories (25% wt/wt) provided by lard, lard and fish oil calories (35%/15%), or lard and corn oil (35%/15%). The high-lard diet increased plasma chylomicron and liver triglycerides. The high-lard diet greatly decreased FAS, HMG-CoA reductase, and LPL activities; it also reduced H-TGL activity. Compared with the lard diet, the lard-fish oil diet decreased plasma TG by drastically lowering chylomicron (4-fold, P < 0.001) and very-low-density lipoprotein levels (P < 0.001). It also reduced high-density lipoprotein levels. The lard-fish oil diet prevented hepatic triglyceride accumulation and decreased FAS activity and mass by 3.5-fold (P < 0.001) but did not further decrease HMG-CoA reductase activity. Adipose tissue LPL activity was 2.5-fold (P < 0.001) higher with the lard-fish oil diet than with the lard diet, and H-TGL activity decreased significantly (-32%, P < 0.01), despite unaltered levels of H-TGL mRNA. These effects were significant with only 10% fish oil concentrate in the lard diet. They were not observed with the lard-corn oil diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Grape Seed Tannins Affect Lipoproteins, Lipoprotein Lipases and Tissue Lipids in Rats Fed Hypercholesterolemic Diets , ,

The effects of monomeric and polymeric grape seed tannins on rat plasma lipoproteins, lipoprotein lipase, hepatic lipase and aortic and hepatic lipid concentration were studied. Male Sprague-Dawley rats received either a normal diet (with no added cholesterol and no tannins), a control diet (hyper-cholesterolemic diet) or hypercholesterolemic diets supplemented with 2% tannin monomers or 2% polymers 3 or 9 wk. Plasma total cholesterol, triacylglycerol, LDL cholesterol and VLDL concentrations were significantly higher and the HDL cholesterol concentration lower in controls and in rats fed the diet supplemented with monomers compared with rats fed polymeric tannins at both time points. Lipoprotein lipase and hepatic lipase activities were significantly higher in control and in monomer-fed groups than in the polymer-fed group. Hepatic and aortic cholesterol and triacylglycerol concentrations were significantly higher in control rats and those fed monomers than in the polymer-fed group. Moreover, plasma HDL cholesterol and hepatic lipase activity were closely associated with low aortic cholesterol and triacylglycerol in rats fed polymeric tannins. These rats also exhibited greater fecal excretion of cholesterol and especially bile acids than the control or monomer-fed groups. Thus dietary grape seed tannins have a pronounced anti-hypercholesterolemic effect by enhancing reverse cholesterol transport and also by reducing intestinal cholesterol absorption and increasing bile acid excretion.

Modification of rat plasma lipoproteins induced by acute immobilization stress.

To determine the influence of acute stress on plasma lipids and lipoproteins, 66 Wistar rats (31 males and 35 females) were immobilized for 10 hours. Previously, these animals were deprived of food for another 10 hours. Because immobilization involves forced fasting, the control group consisted of 58 rats (30 males and 28 females) that fasted for 20 hours. The immobilized animals showed gastric lesions (94% of the males and 83% of the females). Plasma lipoproteins were separated by ultracentrifugation in the following densities: less than 1.006 g/ml (very low-density lipoproteins (VLDL)), 1.006 to 1.040 g/ml (low-density lipoproteins (LDL)), 1.040 to 1.063 g/ml (high-density lipoproteins fraction 1 (HDL1)), and 1.063 to 1.210 g/ml (HDL2). Measurements were adjusted according to hematocrit value. In male rats, immobilization caused a rise in total plasma cholesterol as a consequence of increases in the VLDL, LDL, and HDL1 fractions. In female rats, however, no significant variations were observed in plasma cholesterol, although there was a slight, but significant, increase in VLDL and LDL cholesterol. Immobilization caused hypertriglyceridemia in both sexes as a result of an increase in triglycerides in all classes of lipoproteins, except in HDL2 in both sexes and VLDL in males. Finally, the protein content of VLDL and LDL increased both in male and female rats; HDL2 levels decreased in female rats. These changes suggest an atherogenic character of stress caused by continuous immobilization during 10 hours.