Antiatherogenic effect of Caps HT2, a herbal Ayurvedic medicine formulation

The antiatherogenic effect of a herbal formulation, Caps HT2, was evaluated as antioxidant, anticoagulant, platelet antiaggregatory, lipoprotein lipase releasing, anti-inflammatory and hypolipidaemic activity in rats. The formulation contained the methanolic extracts of selected parts of plants, Commiphora mukul, Allium sativum, Plumbago indica, Semecarpus anacardium, Hemidesmus indicus, Terminalia arjuna, Tinospora cordifolia, Withania somnifera and Ocimum sanctum. The formulation, Caps HT2 was found to scavenge superoxide and hydroxyl radicals; the IC50 required being 55.0 and 610.0 microg/ml respectively. The lipid peroxidation was found inhibited (50%) by 48.5 microg/ml of Caps HT2. The intravenous administration of the formulation (5 mg/kg) delayed the plasma recalcification time in rabbits and enhanced the release of lipoprotein lipase enzyme significantly (p < 0.001). The formulation also inhibited ADP induced platelet aggregation in vitro, which was comparable to commercial heparin. The anti-inflammatory action of the formulation was significant (p < 0.001) with acute and chronic inflammations induced by carrageenan and formalin respectively in rats. The hypolipidaemic effect of Caps HT2 was significant (p < 0.001) with the administration of the formulation, in diet-induced hyperlipidaemia of rats for a period of 30 days. Oral administration of the formulation, Caps HT2 (100, 200, 300 and 400 mg/kg) significantly raised HDL cholesterol levels. The atherogenic index and the reduction in body weight were significant indicating the effectiveness against hyperlipidaemia and obesity. All these results revealed the therapeutic potential of Caps HT2 against vascular intimal damage and atherogenesis leading to various types of cardiovascular problems.     

Beneficial effects of alpha linolenic acid rich flaxseed oil on growth performance and hepatic cholesterol metabolism in high fat diet fed rats

The purpose of the study was to investigate the effect of flaxseed oil (FO), rich in alpha-linolenic acid (ALA) (18:3 n-3) on growth parameters and lipid metabolism of rats fed with high fat diet. High fat diet (HFD) resulted in significant alterations in hepatic lipids, increase in body weight gain and negative effect on lipoprotein metabolism. FO supplementation significantly lowered the increase in body weight gain, liver weight, plasma cholesterol, triglycerides, phospholipids, free fatty acids, high-density lipoprotein (HDL), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein (VLDL), LDL/HDL and TC/HDL ratio in HFD fed rats. FO significantly reduced the hepatic and plasma lipid levels indicating its hypolipidemic activity. On the other hand, oral administration of FO exhibited lower plasma lipoprotein profile as compared to HFD rats. Hepatic protection by FO is further substantiated by the normal liver histological findings in HFD fed rats. These data suggest that FO participate in the normal regulation of plasma lipid concentration and cholesterol metabolism in liver. No adverse effect of FO on growth parameters and plasma lipids in rats fed with fat-free diet. The results of the present study demonstrate that FO may be developed as a useful therapy for hyperlipidemia through reducing hepatic lipids, thereby proving its hypolipidemic activity.     

有氧运动同时补充玉米肽对肥胖大鼠脂肪分解关键酶的影响

目的：研究有氧运动同时补充玉米肽对高脂饮食诱导的肥胖大鼠减脂的作用及其与脂肪分解关键酶甘油三酯脂肪酶（ATGL）和脂蛋白酯酶（LPL）关系。方法：4周龄健康雄性SD大鼠150只,体重160~180 g,随机选取15只作为普通膳食不运动组,给予普通饲料喂养。剩余135只大鼠进行8周的高脂饲料喂养建立肥胖大鼠模型,以体重超过普通膳食不运动组大鼠平均体重的20%作为肥胖大鼠建模成功的标准。将建模成功的肥胖大鼠40只随机分为5组（n=8）：肥胖对照组、酪蛋白组、玉米肽组、运动组和运动+玉米肽组。除酪蛋白组、玉米肽组喂养自制饲料外,其余各组均用普通饲料喂养,运动组每天进行15 m/min,持续时间60 min的跑台运动,每周6天。4周运动和玉米肽干预后取血,检测大鼠血浆中TG、TC、HDL、LDL的含量;取大鼠肾周、附睾脂肪和肝,检测肾周和附睾脂肪的重量,Western blot检测大鼠肝ATGL、脂肪LPL的蛋白表达水平。结果：与肥胖对照组大鼠相比：①运动组、运动+玉米肽组大鼠的体重、附睾和肾周脂肪含量明显降低（P<0.05）,且运动+玉米肽组比运动组下降得更明显（P<0.05）,而其它组大鼠无显著差异。②运动组大鼠血浆TG显著降低,运动+玉米肽组的血浆TG、TC显著降低（P<0.05）,其它组大鼠的TG、TC无显著差异;血浆HDL和LDL各组间均无显著性差异。③运动组和运动+玉米肽组大鼠的肝ATGL、脂肪组织LPL的蛋白水平明显增加（P<0.01）,且运动+玉米肽组比运动组的更显著（P<0.05）;其他两组无显著差异。结论：有氧运动、有氧运动同时补充玉米肽都可以明显降低大鼠的体脂和血脂水平,且后者的作用更强,这可能与其更显著地增加肥胖大鼠肝ATGL和脂肪LPL的蛋白水平有关。而仅仅补充玉米肽不能降低大鼠的体脂和血脂水平。     

Normolipidaemic Activity of Liposomal-Encapsulated Superoxide Dismutase in Rats

To determine the regulatory effects of superoxide dismutase (SOD) on lipid metabolism a simple model of hyperlipidaemia induced by a hypercholesterolaemic (HCT) diet in rat was used. In animals fed a HCT diet, triglyceride (TG) were increased by 126%, total cholesterol (TCT) by 40%, very low density lipoprotein (VLDL) by 124% and the TCT/HDL ratio by 82%. The procedure would therefore appear to model some of the risk factors of atherogenesis.

In animals fed a hypercholesterolemic diet, liposomal Cu-SOD (200μg/kg i. m. every two days; 1000 μg/kg i. m./day) decreased TG by 29 and 49%, TCT by 14 and 36%, TCT/HDL ratio by 32 and 60%, VLDL by 52 and 55% respectively and increased high density lipoprotein cholesterol (HDL-C) by 17 and 46% respectively.

The present experiments show therefore that the administration of liposomal SOD has a marked effect on lipid parameters (particularly TCT and TG) and might therefore reduce the atherogenic risk by increasing HDL and decreasing VLDL and cholesterol atherogenicity ratio (CAR).     

Effect of dietary fiber of “Rihane” barley grains and azoxymethane on serum and liver lipid variables in Wistar rats

The aim of the present study is to evaluate the effects of diet enriched with dietary fiber of barley variety “Rihane” and azoxymethane on serum and liver lipid variables in male rats. Forty male rats were divided into four groups and fed on control diet or experimental diet that contained control enriched with dietary fiber of barley variety “Rihane”. Animals were injected with saline (controls) or azoxymethane (20 mg/kg body weight s.c.) at 7 and 8 weeks of age. The experimental diet significantly decreased cholesterol level compared with the control diet. Rats fed with BR diet significantly increased the serum high-density lipoprotein (HDL) cholesterol and significantly decreased low-density lipoprotein (LDL) cholesterol concentrations. The experimental diet decreased the atherogenic index (p < 0.05) compared with the control diet. Whereas the azoxymethane induced a significant increase of liver lipid, serum LDL and triglyceride concentrations, but it caused a significant reduction of HDL. Consequently, the ratio of HDL/TC decreased significantly compared with the control (p < 0.05). Accordingly, these results indicated that the diet enriched with dietary fiber of barley variety “Rihane” could be effective in decreasing the atherogenic risk factors in rats whereas the use of the azoxymethane as colon-specific carcinogen substance altered the lipid metabolism.     

硫胺素、核黄素和烟酰胺对大鼠体重增长及脂代谢影响的实验研究(英文)

目的:B族维生素以辅酶的形式参与糖、脂肪和蛋白质代谢,本文观察硫胺素、核黄素和烟酰胺补充对高脂饲料诱导大鼠肥胖的影响。方法:采用预防肥胖模型法,2×2×2析因设计分为8组:高脂对照组(F0组),高脂+硫胺素(F1组),高脂+核黄素(F2组),高脂+烟酰胺(F3组),高脂+硫胺素+核黄素(F4组),高脂+硫胺素+烟酰胺(F5组),高脂+核黄素+烟酰胺(F6组),高脂+硫胺素+核黄素+烟酰胺(F7组),每组12只大鼠,给予高脂饲料喂养,同时硫胺素(100 mg/kg bw/d)、核黄素(100mg/kg bw/d)、烟酰胺(250 mg/kg bw/d)灌胃,另设正常对照组(C组)12只,普通饲料喂养,自来水灌胃,15周后,分析其体重、摄食量、体脂重量、血脂等实验前后的变化情况及各组动物之间的差别。结果:经过15周喂养后,高脂喂养大鼠体重比正常对照组平均增加了15.7%;而补充烟酰胺(F3)及联合硫胺素(F5)或核黄素(F6)以及三者联合补充(F7)组高脂喂养大鼠与高脂对照组(F0)相比,体重分别降低了35.0%,30.0%,30.1%和30.6%(P值均小于0.05);甚至比正常对照组大鼠平均体重分别下降了22.8%,17.0%,17.0%和17.7%(P值均小于0.05);而补充核黄素或和硫胺素组大鼠体重没有明显增加或降低(P值均大于0.05)。血脂分析结果显示高脂喂养并联合补充核黄素或/和烟酰胺和/或硫胺素组大鼠血清CHOL和LDL水平明显低于高脂对照组;而高脂喂养并联合补充烟酰胺(F3)及联合硫胺素(F5)或核黄素(F6)以及三者联合补充(F7)组大鼠LDL/HDL比值分别0.29、0.26、0.25和0.26,明显低于F0组的0.37(P值均小于0.05)。结论:大剂量烟酰胺可有效地调节血脂水平和控制肥胖大鼠的体重增长,而核黄素及硫胺素对控制肥胖大鼠体重增长的作用不明显,尚待进一步研究;核黄素只能够降低血脂水平,提示大剂量烟酰胺可通过增加机体的能量代谢来控制体重的增长。     

Increased calcium intake reduces plasma cholesterol and improves vasorelaxation in experimental renal failure

Chronic renal failure (CRF) is associated with abnormal lipid metabolism and high prevalence of vascular complications. Calcium salts are commonly used in CRF as phosphate binders. Increased calcium intake may also lower plasma cholesterol and beneficially influence vascular tone. Therefore, we investigated the influence of increasing dietary calcium from 0.3% to 3.0% for 8 wk after 5/6 nephrectomy (NTX) on plasma cholesterol and mesenteric resistance vessel tone in male Sprague-Dawley rats. The groups were Sham, Sham-Calcium, NTX, and NTX-Calcium (n = 10-11). Blood pressure was modestly elevated after NTX, whereas the plasma creatinine, urea nitrogen, phosphate, and parathyroid hormone levels were clearly increased. The high-calcium diet suppressed plasma phosphate and parathyroid hormone but was without effect on blood pressure. The NTX resulted in 1.6-fold elevation in plasma total cholesterol and 40% reduction in high density-to-low density lipoprotein ratio (HDL/LDL). However, the lipid profile in NTX rats on the high-calcium diet did not differ from sham-operated controls. The endothelium-mediated relaxations induced by acetylcholine were impaired in NTX rats, whereas the response was normalized by a high-calcium diet. No differences in vasorelaxations by the endothelium-independent vasodilator nitroprusside were detected. In conclusion, improved vasorelaxation after a high-calcium diet could be due to reduced plasma total cholesterol and ameliorated HDL/LDL ratio, although decreased plasma phosphate and parathyroid hormone may also play a significant role in the vascular effects of increased calcium intake.     

Hypolipidaemic efficacy of Capparis decidua fruit and shoot extracts in cholesterol fed rabbits

High fat diet caused significant (8-fold) increase in serum total cholesterol in rabbits. Administration of C. decidua fruit extract (50% ethanolic) at the dose of 500 mg/kg body weight significantly reduced serum total cholesterol (61%), LDL cholesterol (71%), triglycerides (32%) and phospholipids (25%). Similarly C. decidua shoot extract lowered serum total cholesterol (48%), LDL cholesterol (57%), triglycerides (38%) and phospholipids (36%).The cholesterol content of aorta was decreased by 44 and 28% in fruit and shoot extract treatment respectively. The HDL to total cholesterol ratio and atherogenic index was significantly decreased in plant extract treated groups suggesting antiatherosclerotic nature of these plant extract. These results reveal the hypolipidaemic potential of C. decidua fruit and shoot.     

Nasturtium officinale reduces oxidative stress and enhances antioxidant capacity in hypercholesterolaemic rats

Nasturtium officinale R. Br. (Brassicaceae) has been used as a home remedy by the people of south eastern (SE) region of Iran as a medicinal plant. This therapeutical application has been attributed to Nasturtium officinale (N. officinale) antioxidant capacity which is mostly tested by means of cell-free assays: 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). In addition, the antioxidant effect of N. officinale extract has been investigated in hypercholesterolaemic rats in vivo. The results revealed that the extract has notable scavenging activity against DPPH radicals as well as potent reducing power in FRAP assay. Intragastric administration of N. officinale (500 mg/kg body weight per day) to groups of hypercholesterolaemic rats for 30 days lowered their blood total cholesterol (TC), triglyceride (TG), and low density lipoprotein cholesterol (LDL-C) levels by 37, 44 and 48%, respectively. However, the blood high density lipoprotein cholesterol (HDL-C) levels in the same treated rats increased by 16%. To evaluate the mechanism(s) of action, we studied the antioxidative potential of N. officinale extract in terms of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) activities and also the level of reduced glutathione (GSH) in the liver tissues. In addition, hepatic tissue malondialdehyde level (MDA, an index of lipid peroxidation) was also determined. Under hypercholesterolaemic condition, hepatic MDA was increased. Moreover, our data indicated GSH depletion along with significant reduction in the activities of CAT and SOD in rats fed high-fat diet rats. On the other hand, significant elevation in the activities of GPx and GR were seen in the same group of rats. Treatment of hypercholesterolaemic rats with N. officinale extract significantly increased the GSH level along with enhanced CAT and SOD activities in liver tissues. Furthermore, N. officinale extract significantly decreased hepatic MDA as well as GPx and GR activities in plant-treated rats. Based on our data, it can be concluded that N. officinale has a high hypolipidaemic activity and this may be attributed to its antioxidative potential.     

Gender related differences in paraoxonase 1 response to high-fat diet-induced oxidative stress

Objective: To evaluate the influence of the pro‐oxidant and proinflammatory state related to dietary obesity on serum paraoxonase 1 (PON1) activity in male and female rats. Methods and Procedures: Adult Wistar rats of both genders were fed on a high‐fat diet to induce weight gain or standard diet for 14 weeks. Body weight was assessed weekly and food intake fortnightly throughout the dietary treatment. Biometrical parameters and serum lipid profile, glucose, insulin, and adipokine levels were measured. To assess the effect of dietary obesity on oxidative stress, levels of liver and serum thiobarbituric acid reactive substances, liver protein carbonyl groups, liver antioxidant enzymes activities, and serum PON1 activities were measured. Results: High‐fat diet feeding induced a significant body weight gain in both male and female rats, as well as a reduction of liver antioxidant protection. High‐fat diet increased serum lipid peroxides in male rats and reduced serum PON1 activities and serum apolipoprotein A‐I (apoA‐I) levels in females, although did not alter serum PON1 or apolipoprotein J (apoJ) levels. Discussion: Our results reveal a gender dimorphism in the high‐fat diet‐induced reduction of serum PON1 activity, which is likely to be related to the greater obese and proinflammatory state achieved in female rats. We suggest that the enhanced oxidative stress caused by dietary increased body weight, on leading to high‐density lipoprotein (HDL), apoA‐I or PON1 oxidation could entail the destabilization of the PON1 association to HDL or a direct inactivation of PON1 enzymatic activity, thus accounting for the decreased serum PON1 activities observed in female rats.     

Hypoglycemic effect of methanol extract of Phyllanthus amarus Schum & Thonn on alloxan induced diabetes mellitus in rats and its relation with antioxidant potential

Methanolic extract of P. amarus was found to have potential anti-oxidant activity as it could inhibit lipid peroxidation, and scavenge hydroxyl and superoxide radicals in vitro. The amount required for 50% inhibition of lipid peroxide formation was 104 microg/ml and the concentrations needed to scavenge hydroxyl and superoxide radicals were 117 and 19 microg/ml respectively. The extract was found to reduce the blood sugar in alloxan diabetic rats at 4th hr by 6% at a dose level of 200 mg/kg body wt and 18.7% at a concentration of 1000 mg/kg body wt. Continued administration of the extract for 15 days produced significant (P < 0.001) reduction in blood sugar. On 18th day after alloxan administration values were almost similar to normal in the group taking 1000 mg/kg body wt.     

Apolipoprotein A-I attenuates palmitate-mediated NF-κB activation by reducing Toll-like receptor-4 recruitment into lipid rafts

While high-density lipoprotein (HDL) is known to protect against a wide range of inflammatory stimuli, its anti-inflammatory mechanisms are not well understood. Furthermore, HDL's protective effects against saturated dietary fats have not been previously described. In this study, we used endothelial cells to demonstrate that while palmitic acid activates NF-κB signaling, apolipoprotein A-I, (apoA-I), the major protein component of HDL, attenuates palmitate-induced NF-κB activation. Further, vascular NF-κB signaling (IL-6, MCP-1, TNF-α) and macrophage markers (CD68, CD11c) induced by 24 weeks of a diabetogenic diet containing cholesterol (DDC) is reduced in human apoA-I overexpressing transgenic C57BL/6 mice compared to age-matched WT controls. Moreover, WT mice on DDC compared to a chow diet display increased gene expression of lipid raft markers such as Caveolin-1 and Flotillin-1, and inflammatory Toll-like receptors (TLRs) (TLR2, TLR4) in the vasculature. However apoA-I transgenic mice on DDC show markedly reduced expression of these genes. Finally, we show that in endothelial cells TLR4 is recruited into lipid rafts in response to palmitate, and that apoA-I prevents palmitate-induced TLR4 trafficking into lipid rafts, thereby blocking NF-κB activation. Thus, apoA-I overexpression might be a useful therapeutic tool against vascular inflammation.     

Mitigating role of lupeol and lupeol linoleate on hepatic lipemic-oxidative injury and lipoprotein peroxidation in experimental hypercholesterolemia

In the present study, the role of pentacyclic triterpenes, lupeol and its ester lupeol linoleate, was studied in relation to hepatic oxidative abnormalities and lipoprotein peroxidation in hypercholesterolemic rats. Hypercholesterolemia was induced in male Wistar rats by feeding them with high cholesterol diet (4% cholesterol + 1% cholic acid; HCD) for 30 days. Pentacyclic triterpenes, lupeol and lupeol linoleate were supplemented (50 mg/kg body wt/day) during the last 15 days. After the experimental period, there was a significant depression in hepatic activities of antioxidant enzymes, SOD (38.39%), CAT (25.03%) and GPx (30.26%) along with a marked fall in the levels of non-enzymic antioxidant molecules GSH (31.39%), vitamin C (46.07%) and vitamin E (42.28%), with a concomitant increase (p<0.001) in lipid peroxidation and in the activities of serum alkaline phosphatase, lactate dehydrogenase and aminotransferases when compared to controls. Treatment with triterpenes decreased lipid peroxidation and reverted the activities of antioxidants (p<0.001 and p<0.01) and marker enzymes to near control. Histopathological findings further confirmed the hepatoprotective nature of triterpenes by showing the normal architecture in treated rats, as against the fatty cellular changes in HCD fed rats. Further, the susceptibility of apo-B containing lipoprotein to oxidation by copper and Fenton’s reagent was increased in in vitro condition in HCD fed rats, whereas the lipoproteins were less susceptible to oxidation in triterpenes treated animals. Therefore, it may be concluded that lupeol and its ester afford protection against the hepatic abnormalities and lipoprotein peroxidation in hypercholesterolemic rats.     

Lignans from the Fruits of Forsythia suspensa (Thunb.) Vahl Protect High-Density Lipoprotein during Oxidative Stress

The objective of the present study was to investigate the beneficial properties lignan compounds obtained from the fruits of Forsythia suspensa (Thunb.) Vahl (Oleaceae) for protecting human high-density lipoprotein (HDL) against lipid peroxidation. The isolated compounds (1-8) inhibited the generation of thiobarbituric acid-reactive substances (TBARS) in a dose-dependent manner with IC50 values from 8.5 to 18.7 microM, since HDL oxidation mediated by catalytic Cu2+. They also exerted an inhibitory effect against thermo-labile radical initiator (AAPH)-induced lipid peroxidation of HDL with IC50 values from 12.1 to 51.1 microM. Compounds 1 and 5 exerted inhibitory effects against the Cu2+-induced lipid peroxidation of HDL, as shown by an extended lag time prolongation at the concentration of 3.0 microM. These results suggest that the antioxidative effects of F. suspensa are due to its lignans and that these constituents may be useful for preventing the oxidation of HDL.     

Antiatherogenic activity of extracts of Argania spinosa L. pericarp: beneficial effects on lipid peroxidation and cholesterol homeostasis

Prevention of lipoprotein oxidation by natural compounds may prevent atherosclerosis via reducing early atherogenesis. In this study, we investigated for the first time the beneficial properties of methanolic extract of argania pericarp (MEAP) towards atherogenesis by protecting human low-density lipoprotein (LDL) against oxidation while promoting high-density lipoprotein (HDL)-mediated cholesterol efflux. By measuring the formation of malondialdehyde (MDA) and conjugated diene as well as the lag phase and the progression rate of lipid peroxidation, the MEAP was found to possess an inhibitory effect. In addition, MEAP reduced the rate of disappearance of alpha-tocopherol as well as the apoB electrophoretic mobility in a dose-dependent manner. These effects are related to the free radical scavenging and copper-chelating effects of MEAP. In terms of cell viability, MEAP has shown a cytotoxic effect (0-40 microg/mL). Incubation of 3H-cholesterol-loaded J774 macrophages with HDL in the presence of increasing concentrations of MEAP enhanced HDL-mediated cholesterol efflux independently of ABCA1 receptor pathways. Our findings suggest that argania seed pericarp provides a source of natural antioxidants that inhibit LDL oxidation and enhance cholesterol efflux and thus can prevent development of cardiovascular diseases.     

Effects of different dietary regimes alone or in combination with standardized Aronia melanocarpa extract supplementation on lipid and fatty acids profiles in rats

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.

     

Specific binding and uptake of apolipoprotein E-free high density lipoproteins by cultured liver parenchymal cells of copper-deficient rats

The influence of copper deficiency on the binding and uptake of apolipoprotein E-free high density lipoprotein (apo E-free HDL) in cultured rat hepatic parenchymal cells was examined in this study. Male weanling Sprague-Dawley rats were randomly divided into two treatments, a Cu-adequate (7.33 mg Cu/kg diet) or a Cu-deficient (1.04 mg Cu/kg diet) group. After 7 weeks, plasma apo E-free HDL were isolated by a combination of ultracentrifugation, gel filtration, and heparin-Sepharose affinity chromatography. Parenchymal cells were isolated from collagenase perfused liver of Cu-deficient and adequate rats and cultured for 16 hours at 37 degrees C prior to incubation with iodinated apo E-free HDL from the same treatment group. Cells were incubated with 5 microg/ml(125) I-apo E-free HDL for 2, 6, or 12 hours in the presence or absence of 200 microg/ml (40-fold) excess unlabeled apo E-free HDL. Increases in specific binding at 4 degrees C and specific cell-associated uptake at 37 degrees C as a function of time were observed with cells and HDL from Cu-deficient rats. Cells were also incubated for 6 hours with 8 concentrations of (125)I-apo E-free HDL in the presence or absence of excess unlabeled HDL. Although no significant increase in specific binding was detected at 4 degrees C as a function of ligand concentration, the response tended to be higher at 5 to 15 microg HDL/ml for the Cu-deficient treatment. However, at 37 degrees C the specific cell-associated uptake was increased markedly with cells and HDL from Cu-deficient rats. The observed increases in HDL binding and uptake indicate that these processes may be enhanced in Cu-deficient rats. These data are also consistent with recent in vivo results which indicate that plasma clearance and tissue uptake of HDL are increased in Cu-deficient rats.     

D-galactosamine induced hepatitis in the rabbit: effect on lecithin:cholesterol acyltransferase activity, plasma lipid transfer protein activity and high density lipoproteins

Hepatitis was induced in rabbits by a single intraperitoneal injection of D(+)-galactosamine-HCl (750 mg/kg body wt). Plasma lecithin:cholesterol acyltransferase activity fell to 5% and lipid transfer protein activity to 50% of control values 48 hr after injection. Discoid high density lipoprotein began to appear in plasma of treated rabbits 36 hr after injection, along with populations of high density lipoprotein (HDL) which were both smaller (radius 3.7 nm) and larger (radius 5.9 nm) than the original HDL population (radius 4.8 nm).     

High density lipoprotein can modulate the inhibitory effect of oxLDL on prostacyclin generation by rat aorta in vitro

To examine the effect of oxidized low density lipoprotein (oxLDL) on prostacyclin (PGI2) generation by rat aorta in vitro and whether high density lipoprotein (HDL) has any protective effect against the inhibition of PGI2 generation induced by oxLDL is the objective of this study. Preincubation of aortas with oxLDL resulted in significant inhibition of PGI2 generation compared to preincubation with normal low density lipoprotein (nLDL) or buffer only. The inhibitory effect of oxLDL resided in its lipid moiety while the lipid fraction of nLDL showed no effect. Aortas preincubated with 10 microg/ml of lyso phosphatidycholine (lyso PC) also showed 30% inhibition of PGI2 generation, indicating that lyso PC was among the lipid components of oxLDL which inhibited PGI2 generation. Preincubation of aortas with a mixture of HDL and oxLDL at a ratio of 10:1 showed a significant recovery of PGI2 generation compared to aortas preincubated with only oxLDL, indicating a protective role for HDL. When HDL was incubated with oxLDL the transfer of lyso PC from oxLDL to HDL suggested that HDL trapped lyso PC from oxLDL thus preventing it from acting on the aorta. However, when a mixture of HDL and oxLDL at a ratio of 3:1 was preincubated with aortas, no protective effect of HDL was observed. Preincubation of aortas with a mixture of HDL plus oxLDL at a ratio of 8:1, which was incubated for 1 h at 37 degrees C, produced significantly less PGI2 than aortas preincubated only with oxLDL, indicating that HDL under these conditions was not protective but even enhanced the inhibitory effect of oxLDL. Similarly, aortas preincubated with HDL plus whole oxLDL (at a ratio of 10:1); containing all the small molecular weight oxidation products and characterized by high levels of thiobarbituric acid reactive substance (TBARS) and lipid hydroperoxides; produced significantly less PGI2 than aortas preincubated with whole oxLDL. These results were evaluated in light of possible modification of HDL by oxLDL and its lipid oxidation products such as aldehydes and lipid peroxides. The modified HDL can add more lipid peroxides and increase the effectiveness of lipid peroxides originally present in oxLDL.     

A new synthetic class A amphipathic peptide analogue protects mice from diet-induced atherosclerosis

Several synthetic class A peptide analogues have been shown to mimic many of the properties of human apo A-I in vitro. A new peptide [acetyl-(AspTrpLeuLysAlaPheTyrAspLysValPheGluLysPheLysGluPhePhe)-NH2; 5F], with increased amphipathicity, was administered by intraperitoneal injection, 20 microg/day for 16 weeks, to C57BL/6J mice fed an atherogenic diet. Mouse apo A-I (MoA-I) (50 microg/day) or phosphate-buffered saline (PBS) injections were given to other mice as controls. Total plasma cholesterol levels and lipoprotein profiles were not significantly different between the treated and control groups, except that the mice receiving 5F or MoA-I had lower high density lipoprotein (HDL) cholesterol when calculated as a percentage of total cholesterol. No toxicity or production of antibodies to the injected materials was observed. When HDL was isolated from high fat diet-administered mice injected with 5F and presented to human artery wall cells in vitro together with human low density lipoprotein (LDL), there were substantially fewer lipid hydroperoxides formed and substantially less LDL-induced monocyte chemotactic activity than with HDL from PBS-injected animals. Injection of human apo A-I produced effects similar to 5F on lipid peroxide formation and LDL-induced monocyte chemotactic activity, but injection of MoA-I was significantly less effective in reducing lipid hydroperoxide formation or lowering LDL-induced monocyte chemotactic activity. Mice receiving peptide 5F had significantly less aortic atherosclerotic lesion area compared with mice receiving PBS, whereas lesion area in mice receiving MoA-I was similar to that of the PBS-injected animals. This is the first in vivo demonstration that a model class A amphipathic helical peptide has antiatherosclerotic properties. We conclude that 5F inhibits lesion formation in high fat diet-administered mice by a mechanism that does not involve changes in the lipoprotein profile, and may have potential in the prevention and treatment of atherosclerosis.