The influence of dietary olive oil and margarine on aortic cholesterol accumulation in cholesterol-fed rabbits maintained at similar plasma cholesterol level.

The present study compares the atherogenicity of a standard diet and diets with 10% olive oil or 10% margarine added, in rabbits maintained at a mean plasma cholesterol level of about 20 mM for 13 weeks. Each group consisted of 15 animals. The distribution of cholesterol in plasma between VLDL, IDL, LDL and HDL was similar in the 3 groups. The thoracic aortic cholesterol accumulation was 16.6 +/- 1.6, 11.4 +/- 1.0 (P < 0.05) and 12.6 +/- 1.7 (P > 0.05) nmol/mg wet weight for the group receiving standard diet, diet with 10% olive oil added and diet with 10% margarine added, respectively. There was no significant difference between groups in the occurrence of the atherosclerotic changes in the proximal and distal parts of coronary arteries, abdominal aorta and renal arteries. The occurrence of atherosclerotic changes in the pulmonary arteries was equal in the groups receiving standard diet and diet with 10% margarine added while it was significantly lower (P < 0.05) in the group receiving diet with 10% olive oil added. The atherosclerotic changes at the aortic orifice of coronary arteries were quanticated morphometrically and were most severe in the group on the standard diet. The results indicate a comparable atherogenic effect of 10% olive oil or margarine addition to standard diet on development of atherosclerosis in rabbits maintained at a similar plasma cholesterol level. The study also suggests that supplementation of olive oil or margarine to standard rabbit diet leads to lower cholesterol accumulation in the thoracic aorta compared with standard diet, an effect not modulated by changes in plasma cholesterol concentrations.     

人血高密度脂蛋白注射液对高胆固醇饲料所致新西兰白兔动脉粥样硬化病变的作用及与洛伐他汀的比较

目的研究人血高密度脂蛋白(HDL)注射液对喂高胆固醇饲料家兔主动脉粥样指纹病变的影响.方法实验家兔给与1%胆固醇饲料8周.在此期间,HDL组每只家兔每周静脉注射50 mg人血HDL;洛伐他汀组每只家兔每天皮下注射10mg洛伐他汀;安慰剂组每只家兔每天静脉注射20mL生理盐水.人血HDL注射液由清华紫光古汉生物制药集团有限公司生产并提供.结果在试验期间,各组实验动物喂高胆固醇饲料后血脂水平均有升高.第八周后,实验动物主动脉内膜表面富脂粥样病变面积比分别为安慰剂组32.6%±21.7%(x±s,下同);HDL组9.16%±7.87%;洛伐他汀组20.8%±13.1%.血清总胆固醇水平分别为安慰剂组10.0±2.30g/L;HDL组2.92±1.41g/L;洛伐他汀组3.74±1.73g/L.血清HDL胆固醇水平分别为安慰剂组0.43±0.12g/LHDL组 0.62±0.23g/L;洛伐他汀组0.23±0.14g/L.HDL组血管壁胆固醇含量比安慰剂组和洛伐他汀组都明显降低,说明人血HDL具有比洛伐他汀更有效的抗动脉粥样硬化病变作用.结论人血HDL能够有效地抑制喂胆固醇饲料家兔主动脉粥样病变的作用,并能够调节血脂,减少动脉壁脂质沉积.     

普罗布考对高密度脂蛋白亚组分与抗氧化功能的影响

目的研究普罗布考对动脉粥样硬化(AS)兔HDL亚组分及氧化功能的影响,探讨普罗布考抗AS机制。方法选择18只新西兰大白兔随机分为:对照组6只,饲以普通饲料;AS组6只,饲以高脂饲料;普罗布考组6只,饲以高脂饲料基础上给予普罗布考400 mg/(kg·d)。1 2周后酶法检测血脂;分光光度计法检测血清对氧磷酶1(PON1)活性;采用化学沉淀法检测HDL_2/HDL;组织切片和HE染色检测主动脉内膜中层厚度(IMT)和动脉斑块/血管面积。结果实验12周后,与AS组比较,普罗布考组血清TC、LDL-C、HDL-C水平明显下降(P0.01);PON1活性明显升高(P=0.000);HDL_2/HDL明显降低(P=0.000),主动脉IMT明显减小(P=0.000),斑块面积/血管腔面积明显降低(P=0.002)。结论普罗布考通过提高PON1活性,降低HDL_2/HDL而改善HDL功能,减少主动脉IMT及斑块面积/血管腔面积,延缓AS进展。     

Effect of pollen extract on the development of experimental atherosclerosis in rabbits

Our previous studies have shown that the pollen extract, Cernitin, reveals lipid-lowering properties in animals and humans. The present study was designed to investigate the influence of Cernitin on the development of experimental atherosclerosis in rabbits over a period of 12 weeks. Forty male mongrel rabbits were divided into 4 equal groups: (1) controls, (2) animals receiving high-fat diet (HFD) containing cholesterol and coconut oil, (3) HFD + pollen extract, and (4) HFD + clofibrate. The most pronounced reduction in lipid metabolism and in the severity of plaque formation occurred after the pollen extract had been applied. The total cholesterol content in serum and liver homogenate was depressed by 67% and 45%, respectively, while the serum HDL cholesterol and alpha-lipoproteins level was increased by 19% and from 7.73% to 21.73% respectively. The cytochrome P-450 content in the liver microsomes was elevated by 98% (nmol/g liver). Atherosclerotic plaque intensity at 12 weeks, measured planimetrically, averaged 85.5% in HFD-fed animals vs 33.7% in pollen extract-treated rabbits. These findings suggest that Cernitin, in addition to significantly lowering serum lipid levels in rabbits on an experimental diet, may modify lipid deposition in major arteries.     

Preventive effect of gliclazide on experimental atherosclerosis in rabbits

Summary Administration of a hypoglycaemic sulphonamide, gliclazide, at 10 mg/kg/day p. o. to rabbits for 60 days did not affect the development of plasma lipid disturbances induced by a high cholesterol diet. The accumulation of cholesterol in the liver was significantly reduced by up to 34% when compared with animals on the high cholesterol diet. The high concentrations of glycerides and fatty acids in the aorta were significantly decreased towards normal values and histology showed that the gliclazide strongly inhibited the development of aortic and particularly coronary lesions induced by the atherogenic diet. A normal appearance of coronary arteries was noted in more than 50% of cases.     

The effect of dietary linoleic acid and pectin on lipoprotein and apolipoprotein A1 concentrations in rhesus monkeys

Medium term effects (3 months) on serum lipoprotein levels of a diet with a high P/S ratio (2.2) and a low P/S ratio (0.3) were investigated in 13 normolipoproteinemic rhesus monkeys. Both diets were studied with and without added gel-forming fibre, as pectin. Addition of pectin did not have major influences on serum lipid levels. Changing from a low to a high P/S diet resulted in a significant decrease of total cholesterol (23%) and LDL cholesterol (18%) levels, but also HDL cholesterol (23%) and apolipoprotein A1 (Apo A1; 13%) concentrations fell significantly. However, after 12 weeks on the high P/S diet, HDL cholesterol concentrations rose by 24%, not significantly different from the levels during the low P/S diet. We conclude that the medium-term effects of a high P/S diet are a decrease in LDL cholesterol with only a transient effect on HDL cholesterol.     

Ramipril prevents impaired endothelium-dependent relaxation in arteries from rabbits fed an atherogenic diet

Endothelium-dependent relaxation in arteries is attenuated in clinical and experimental atherosclerosis. This study investigates the endothelial preservation properties of the angiotensin converting enzyme inhibitor, ramipril, by assessing its ability to restore endothelium-dependent responsiveness in blood vessels from rabbits fed an atherogenic diet (0.25% cholesterol; 3% coconut oil; 12 weeks). Seven rabbits fed the atherogenic diet received ramipril (3 mg/kg mixed into their food daily) and 6 rabbits were maintained on the atherogenic diet alone. Control rabbits (n = 6) were fed a standard diet and did not receive ramipril. At the end of the dietary intervention, the rabbits were killed and blood was collected for measurement of the lipid profile. The thoracic aorta was isolated and half was frozen for pathologic review while the other half was cut into rings and placed in a muscle bath for measurement of isometric force development. Dose response curves to phenylephrine (10⁻⁹ to 10⁻⁵ M) and angiotensin II (10⁻¹⁰ to 3 × 10⁻⁷ M) were completed. There was a minimal decrease in responsiveness to phenylephrine in vessels from rabbits eating the atherogenic diet compared with controls and no significant differences in the response to angiotensin II for any of the vessels. Following contraction by phenylephrine, acetylcholine (10⁻⁹ to 10⁻⁵ M) and nitroglycerin (10⁻¹⁰ to 10⁻⁵ M) dose response curves were completed. Relaxation to acetylcholine in aortic rings from control rabbits was observed, although in arteries from atherogenic rabbits relaxation was attenuated. This effect was prevented in the atherogenic rabbits fed ramipril. Responsiveness to the endothelium-independent vasodilator, nitroglycerin, was similar in arteries from the three rabbit groups. Total cholesterol levels were elevated in the rabbits fed the atherogenic diet and in the rabbits fed the atherogenic diet containing ramipril. High density lipoprotein (HDL) cholesterol levels were not affected by the atherogenic diet alone, but when ramipril was added, there was a significant increase in HDL cholesterol levels. The percentage of aortic surface covered with lipid streaks was not significantly different in the three rabbit groups. We conclude that ramipril prevents endothelial dysfunction in arteries from rabbits fed an atherogenic diet. Mechanistically, this effect of ramipril on the endothelium must occur prior to the release of nitric oxide as no alteration in the dose response curve to nitroglycerine could be identified. Additionally, this improvement in endothelial function in rabbits supplemented with ramipril appears to be independent of morphologic changes in response to the atherogenic diet.     

Effect of Ethanol Dose on Low density Lipoproteins and High Density Lipoprotein Subfractions

Male squirrel monkeys were fed increasing caloric percentages (0, 12, 24, and 36%) of ethanol (ETOH) substituted isocalorically for carbohydrate as part of a chemically defined liquid diet to assess how alcohol dose modifies plasma lipoproteins and liver function. A separate group of primates was used to define the dose at which elevations in plasma apolipoprotein B first occurred and to measure plasma alcohol levels. ETOH caused a dose-related, linear increase in high density lipoprotein (HDL) cholesterol which was primarily the result of increments in coronary protective HDL2 cholesterol. HDL2 total mass (lipid + protein) followed the pattern of HDL2 cholesterol. Animals fed the 12% regimen had plasma ETOH levels of approximately 49 mg/dl, the lowest low density lipoprotein (LDL) cholesterol, and the highest HDL2/HDL3 cholesterol ratio. Significant elevations in apolipoprotein B first appeared at 18% ETOH while higher doses (24 and 36%) caused increases in LDL cholesterol and HDL3, reduced HDL2/HDL3 ratios, and plasma alcohol levels of 142 and 202 mg/dl, respectively. Liver function tests were normal for all animals. Our results indicate that while a moderate ETOH caloric intake (12%) produces an antiatherogenic lipoprotein profile (decreases LDL/HDL, increases HDL2/HDL3), any coronary protection afforded by continued increases in HDL2 at higher doses may be attenuated by concurrent atherogenic alterations (increases LDL cholesterol, increases apolipoprotein B).     

The effect of niceritrol (pentaerythritoltetra-nicotinate) and clofibrate upon hyperlipemia and atherosclerosis induced in rabbits by cholesterol-free semisynthetic diets

Hyperlipemia and atherosclerosis were induced in rabbits by cholesterol-free semisynthetic diets containing 8–15% coconut oil or 8% butter.

The coconut oil diet increased the levels of plasma cholesterol and triglycerides (TG) and also produced moderate lipid infiltration of the aorta. Addition of 0.5% niceritrol to the diet significantly inhibited the increase of cholesterol and TG in total plasma and in the “VLD”- and “LD”-fractions. The lipid-infiltrated area and the contents of total cholesterol and cholesterol esters of the aorta were reduced by niceritrol. Clofibrate in a concentration of 0.33% gave no significant reduction of the lipid levels in the plasma or aorta. Niceritrol combined with clofibrate did not protect the aorta to a higher degree than niceritrol alone.

The butter diet induced a more moderate hypercholesterolemia with a mean level of about 300 mg/100 ml but with no increase of plasma TG. Addition of niceritrol resulted in somewhat lower mean values of plasma cholesterol but the reduction was not significant. The butter diet induced a slight atherosclerosis of a variable degree. After addition of niceritrol to the diet the mean level of aortic cholesterol lay within the normal region.     

Overexpression of human hepatic lipase and ApoE in transgenic rabbits attenuates response to dietary cholesterol and alters lipoprotein subclass distributions

The effect of the expression of human hepatic lipase (HL) or human apoE on plasma lipoproteins in transgenic rabbits in response to dietary cholesterol was compared with the response of nontransgenic control rabbits. Supplementation of a chow diet with 0.3% cholesterol and 3.0% soybean oil for 10 weeks resulted in markedly increased levels of plasma cholesterol and VLDL and IDL in control rabbits as expected. Expression of either HL or apoE reduced plasma cholesterol response by 75% and 60%, respectively. The HL transgenic rabbits had substantial reductions in medium and small VLDL and IDL fractions but not in larger VLDL. LDL levels were also reduced, with a shift from larger, more buoyant to smaller, denser particles. In contrast, apoE transgenic rabbits had a marked reduction in the levels of large VLDLs, with a selective accumulation of IDLs and large buoyant LDLs. Combined expression of apoE and HL led to dramatic reductions of total cholesterol (85% versus controls) and of total VLDL+IDL+LDL (87% versus controls). HDL subclasses were remodeled by the expression of either transgene and accompanied by a decrease in HDL cholesterol compared with controls. HL expression reduced all subclasses except for HDL2b and HDL2a, and expression of apoE reduced large HDL1 and HDL2b. Extreme HDL reductions (92% versus controls) were observed in the combined HL+apoE transgenic rabbits. These results demonstrate that human HL and apoE have complementary and synergistic functions in plasma cholesterol and lipoprotein metabolism.     

Dietary interventions in north Karelia, Finland and south Italy. Modification of thromboxane B2 formation in platelets of male subjects only

The effects of dietary interventions, based on changes of total fat, saturated fatty acids and cholesterol contents and of the polyunsaturated/saturated (P/S) fatty acid ratio of the diet, were studied in normal male and female subjects, living in North Karelia, Finland, and South Italy. In North Karelia the increase of P/S ratio (from 0.15 to 1.2) of the diet for a 6-week period resulted in reduced thromboxane B2 (TxB2) production by collagen-stimulated platelets only in male subjects, whereas plasma total, LDL and HDL cholesterol were reduced in both sexes. After a 6-week return to the original diet, plasma lipid levels were restored in all subjects. In the South Italy study, changes in platelet TxB2 production were observed only after return to the original diet in male subjects. Total and LDL cholesterol were significantly increased during the dietary intervention and returned toward baseline levels after switch back to the original diet. These data indicate that the increase of the P/S ratio in the diet reduces platelet TxB2 formation only in men.     

高密度脂蛋白对其动脉粥样硬化家兔肝细胞膜受体活性的影响

为了研究高密度脂蛋白对抗动脉粥样硬化的作用机理,采用酶联免疫受体分析法对注射高密度脂蛋白的动脉粥样硬化家兔肝细胞提高密度脂蛋白受体活性进行了检测。结果表明,人血浆高密度脂蛋白虽不能降低高脂饲养的家兔血脂含量,但可显著降低其肝脏脂质水平和显著升高胆汁脂质水平。     

Evidence for an inverse relation between plasma triglyceride and aortic cholesterol in the coconut oil/cholesterol-fed rabbit

Rabbits fed a commercial chow diet containing 0.5% cholesterol and 14% coconut oil developed more severe hyperlipidemia and atherosclerosis than rabbits fed the same diet containing olive oil in place of coconut oil. Average plasma cholesterol was twice as high in the coconut oil/cholesterol-fed rabbits than in olive oil/cholesterol-fed rabbits. Final plasma triglycerides, although highly variable, were approx. 20-fold higher than basal plasma triglyceride in coconut oil/cholesterol-fed rabbits; plasma triglyceride in olive oil/cholesterol-fed rabbits remained unchanged throughout the study period. In coconut oil/cholesterol-fed rabbits, a direct relationship between plasma triglyceride and aortic cholesterol was not found. Plasma cholesterol and aortic cholesterol were also not correlated at a statistically significant level (r = 0.26, P greater than 0.25). However, when both plasma cholesterol and triglyceride were simultaneously introduced as predictors of aortic cholesterol, the correlation between these plasma lipids and aortic cholesterol became highly significant (r = 0.64, P less than 0.02). Aortic cholesterol increased in proportion to plasma cholesterol concentrations but appeared to be inversely related to plasma triglyceride levels.     

Overexpression of lecithin:cholesterol acyltransferase in transgenic rabbits prevents diet-induced atherosclerosis.

Lecithin:cholesterol acyltransferase (LCAT) is a key plasma enzyme in cholesterol and high density lipoprotein (HDL) metabolism. Transgenic rabbits overexpressing human LCAT had 15-fold greater plasma LCAT activity that nontransgenic control rabbits. This degree of overexpression was associated with a 6.7-fold increase in the plasma HDL cholesterol concentration in LCAT transgenic rabbits. On a 0.3% cholesterol diet, the HDL cholesterol concentrations increased from 24 +/- 1 to 39 +/- 3 mg/dl in nontransgenic control rabbits (n = 10; P < 0.05) and increased from 161 +/- 5 to 200 +/- 21 mg/dl (P < 0.001) in the LCAT transgenic rabbits (n = 9). Although the baseline non-HDL concentrations of control (4 +/- 3 mg/dl) and transgenic rabbits (18 +/- 4 mg/dl) were similar, the cholesterol-rich diet raised the non-HDL cholesterol concentrations, reflecting the atherogenic very low density, intermediate density, and low density lipoprotein particles observed by gel filtration chromatography. The non-HDL cholesterol rose to 509 +/- 57 mg/dl in controls compared with only 196 +/- 14 mg/dl in the LCAT transgenic rabbits (P < 0.005). The differences in the plasma lipoprotein response to a cholesterol-rich diet observed in the transgenic rabbits paralleled the susceptibility to developing aortic atherosclerosis. Compared with nontransgenic controls, LCAT transgenic rabbits were protected from diet-induced atherosclerosis with significant reductions determined by both quantitative planimetry (-86%; P < 0.003) and quantitative immunohistochemistry (-93%; P < 0.009). Our results establish the importance of LCAT in the metabolism of both HDL and apolipoprotein B-containing lipoprotein particles with cholesterol feeding and the response to diet-induced atherosclerosis. In addition, these findings identify LCAT as a new target for therapy to prevent atherosclerosis.     

A diet high in saturated fat and sucrose alters glucoregulation and induces aortic fatty streaks in New Zealand White rabbits

A new and convenient animal model for studying peripheral vascular and coronary artery disease in diabetes was established in this study. Male New Zealand White rabbits weighing approximately 2 kg were divided into 2 groups: a normal control group fed standard laboratory chow and a diabetogenic diet-fed group received a high-fat/high-sucrose diet. The high-fat/high-sucrose diet (contained 10% lard and 37% sucrose) feeding was maintained for 6 months. Plasma total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, superoxide dismutase, nitric oxide, nitric oxide synthase, insulin, and glucose were quantitated at monthly or bimonthly intervals. The aortic fatty streak lesions were quantified following lipid staining with Sudan IV. The aortic samples were observed by electron microscopy. High plasma triglyceride and glucose concentrations were induced. At the end of 6 months, the aortic fatty streak lesions were present in the animals' vascular specimens. As far as we know, this is the first report that demonstrates that New Zealand White rabbits can develop obvious aortic fatty streaks by feeding a high-fat/high-sucrose diet. Our results suggest that New Zealand White rabbits fed a high-fat/high-sucrose diet would provide a convenient model for studying peripheral vascular-and coronary artery disease in diabetes.     

Exogenous estrogens attenuate dietary hypercholesterolemia and atherosclerosis in the rabbit

The effect of exogenous estrogens upon the response to dietary cholesterol was tested in New Zealand White rabbits. Cholesterol-fed, untreated rabbits had a 10-fold increase in plasma cholesterol in 12 wk. The major increase of cholesterol occurred in very low density lipoproteins (VLDL, 43.5-fold) followed by intermediate density lipoproteins (IDL, 26-fold) and low density lipoproteins (LDL, 6-fold) with no change in high density lipoproteins (HDL). These diet induced changes were markedly attenuated in the estrogen treated animals, in whom plasma cholesterol increased only 5-fold. This increase was distributed among LDL (6-fold), IDL (7.5-fold), and VLDL (9-fold), similarly with no change in HDL. All the lipoproteins in both groups of animals were considerably enriched in cholesterol during cholesterol feeding as indicated by a high cholesterol/protein and cholesterol/triglyceride ratio. However, these ratios were lower in estrogen treated animals. There were no differences in the feed consumption, body weight or cholesterol absorption between the two groups of animals. Rabbits fed a cholesterol-rich diet but not treated with estrogen had well developed lesions in all parts of the aorta with higher content of cholesterol and phospholipids as compared to those injected with estrogen, whose aortas were completely clear of visible atherosclerosis. Equivalent total hypercholesterolemia was induced in other estrogen-treated rabbits by feeding twice the cholesterol dietary content (0.2%) as in nonestrogen-treated animals. Aortic atherosclerosis was far more evident in the latter, which had higher proportions of cholesterol-rich lipoproteins of d < 1.006 g/ml.     

Probucol reduces oxysterol formation in hypertensive rabbits

The role of lipid peroxidation during the pathogenesis of atherosclerosis has been described through numerous studies and has provided compelling evidence for free radical-mediated processes that link hypertension with atherosclerosis. However, there remains only limited information concerning peroxidative processes in hypertension and their modulation by antioxidants. In the present study, the formation of cholesterol oxidation products was used as a measure of in vivo lipid peroxidation after hypertension induced by coarctation of the aorta in New Zealand White rabbits. The rabbits were fed a standard chow diet devoid of cholesterol or cholesterol oxidation products such that the measured cholesterol oxides in the plasma and aortic tissues would most plausibly arise from endogenous oxidation of cholesterol. After 12 weeks of hypertension, all of the measured cholesterol oxides increased significantly over baseline levels in the surgically coarctated animals; however, this increase was significantly less in hypertensive probucol-treated animals. Similarly, the cholesterol oxide content of aortic tissue from the surgically coarctated animals was significantly greater than that found in normotensive control aortas, and probucol treatment significantly reduced the increase in cholesterol oxide content of aortic tissue relative to that of hypertensive animals not receiving the antioxidant. These findings in hypertensive animals suggest that cholesterol oxidation products measured in plasma and aortic tissue can be derived from endogenous free radical activity and that this activity is enhanced under specific pathological conditions.     

Hyperglycemia in normotriglyceridemic, hypercholesterolemic insulin-treated diabetic rabbits does not accelerate atherogenesis

Severely hyperlipidemic alloxan-diabetic cholesterol-fed rabbits were treated with different daily doses of insulin in order to study the effect of insulin on plasma lipids, lipoproteins and postheparin lipoprotein lipase activity. At plasma triglyceride levels of 15,000 mg/dl, untreated diabetic rabbits carried 73% (1950 mg/dl) of plasma total cholesterol in lipoproteins with a diameter larger than 75 nm (Sf greater than 400), 25% in smaller very low density lipoproteins (VLDL) and 1% in both low and high density lipoproteins (LDL, HDL). Insulin treatment greatly reduced plasma total cholesterol and triglyceride concentrations. The decrease of plasma total cholesterol concentration was paralleled by a decrease in the cholesterol of the largest lipoproteins (Sf greater than 400) and an increase in cholesterol of both smaller very low density lipoproteins and low density lipoproteins. At the same time, postheparin plasma lipoprotein lipase activity increased 2-8-fold. When plasma triglyceride levels were normalized by insulin treatment, the lipoprotein cholesterol distribution in diabetic cholesterol-fed rabbits was similar to that of normal cholesterol-fed rabbits. To study development of atherosclerosis, diabetic rabbits were cholesterol-fed and treated with insulin for eight weeks such that the triglyceride levels were normalized, but plasma glucose levels were still greatly elevated. Nondiabetic rabbits were cholesterol-fed simultaneously. Plasma cholesterol and triglyceride levels were similar in the two groups of rabbits, as well as cholesterol in Sf greater than 400 or smaller VLDL and cholesterol in HDL. However, LDL-cholesterol concentration in the insulin-treated diabetic rabbits was 1.5-2 times that in the nondiabetic rabbits. The two groups of rabbits developed similar degrees of atherosclerosis, as judged by aortic cholesterol content. Apparently, partially controlled diabetes in cholesterol-fed rabbits does not accelerate atherogenesis beyond that observed in nondiabetic cholesterol-fed rabbits.     

幽门螺杆菌感染诱导C57BL/6小鼠动脉硬化的病理损伤及其在粥样斑块组织中的DNA分析

目的 建立幽门螺杆菌(HP)感染的C57BL/6小鼠动脉粥样硬化模型,探讨HP感染在动脉粥样硬化发病机制中的作用.方法 将48只C57BL/6小鼠随机分为4组,即HP灌饲联合高脂饮食组、单纯HP灌饲组、单纯高脂饮食组以及生理盐水对照组,每组12只小鼠.52周后观察4组小鼠主动脉粥样硬化发生率及其病理损伤程度、胃黏膜病理特征、血脂水平,并以PCR方法检测小鼠主动脉中HP尿素酶A(ureaseA,ureA)、尿素酶C(ureaseC,ureC)、细胞毒素相关基因A(cytotoxin-associated gene A,cagA)、空泡毒素A(vacuolating cytotoxin A,vacA)的DNA表达.结果 (1)单纯HP灌饲组和生理盐水对照组无动脉粥样硬化发生,而HP灌饲联合高脂饮食组和单纯高脂饮食组动脉粥样硬化发生率高达100%和91.6%,两组问差异无统计学意义.(2)HP灌饲联合高脂饮食组、单纯HP灌饲组、单纯高脂饮食组的总胆固醇(TC)、低密度脂蛋白(LDL)和甘油三酯(TG)水平高于生理盐水对照组(P均<0.05),而高密度脂蛋白(HDL)水平低于生理盐水对照组(P均<0.05).且HP灌饲联合高脂饮食组的TC、LDL和TG水平高于单纯高脂饮食组,HDL水平低于单纯高脂饮食组,组间差异有统计学意义,P均<0.05.(3)HP灌饲联合高脂饮食组Roberts & Thompson评分总分和斑块中泡沫细胞最多数目均高于单纯高脂饮食组,P均<0.05.(4)12只HP灌饲联合高脂饮食组的小鼠动脉组织中有5例ureC检测出阳性,但未检测出ureA、cagA和vacA DNA.同时在其他3组小鼠动脉组织中均未检出HP的DNA表达.结论 给C57BL/6小鼠灌饲HP可加重高脂饮食诱发的血脂代谢紊乱和动脉粥样硬化病理损伤程度,同时在HP感染的小鼠动脉粥样硬化组织中可检出HP的ureC DNA,提示HP感染与动脉粥样硬化的发生发展可能相关.     

Effect of clentiazem on lipid profile, lipoprotein composition and aortic fatty streaks in cholesterol-fed rabbits

Numerous experimental studies have reported that common antihypertensive drugs such as diuretics, beta-blockes, and methyldopa have adverse effects on plasma lipids and lipoproteins. The present study was designed to define the effect of clentiazem (10 mg/kg/day) an antihypertensive drug, on hyperlipidemia in rabbits on a cholesterol-rich diet (1%) for 12 weeks. Compared with controls, clentiazem treated rabbits had lower plasma concentrations of triglycerides (55%), total cholesterol (24%), free cholesterol (27%), esterified cholesterol (23%) and phospholipids (24%). The decrease in cholesterol was accounted for by a reduction of VLDL-cholesterol (13%), IDL-cholesterol (24%) and primarily LDL-cholesterol (45%). Neither HDL-cholesterol nor chemical composition of VLDL, IDL, LDL and HDL was altered. When the aortic atherosclerotic involvement was evaluated by computerized planimetry, a 24% reduction of lesions was noted in clentiazem treated animals (P < 0.05). Similarly, cholesterol content extracted from aortic wall was decreased. Our data therefore demonstrated that clentiazem is a potential antiatherosclerotic agent capable of decreasing plasma lipids and atherogenic lipoproteins as well as aortic fatty streaks.