Distribution of cholesterol and triglycerides among lipoprotein fractions in fat-fed rabbits at different levels of serum cholesterol

Brattsand, Ralph

doi:10.1016/0021-9150(76)90121-0

Cited by 33 publications

(11 citation statements)

References 23 publications

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“…There were no significant differences in LDL-C between the groups. This is in accordance with previous findings (23), showing that LDL becomes "saturated" with cholesterol in cholesterol-fed rabbits, and that further increase in serum cholesterol accumulates in the VLDL fraction. Estradiol did not increase the concentration of HDL-C as seen in women.…”

Section: Discussionsupporting

confidence: 94%

Estrogen monotherapy and combined estrogen-progestogen replacement therapy attenuate aortic accumulation of cholesterol in ovariectomized cholesterol-fed rabbits.

Haarbo¹,

Leth-Espensen²,

Stender³

et al. 1991

J. Clin. Invest.

199

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Cardiovascular disease is currently the leading cause of death among women in the United States. To investigate the effect of postmenopausal hormone therapy on atherogenesis, we studied 75 cholesterol-fed female rabbits for 19 wk. The rabbits were randomly assigned to five groups. Four groups underwent bilateral ovariectomy followed by treatment with either 17 #l-estradiol, 17 f-estradiol plus norethisterone acetate, 17 ,-estradiol plus levonorgestrel, or placebo. The fifth group had a sham operation and received placebo. The hormone groups had only one-third of the aortic accumulation of cholesterol found in the placebo groups, a difference that was highly statistically significant (P < 0.0001). No significant differences in aortic accumulation of cholesterol were found in the hormone groups. This indicates that estrogen attenuates atherogenesis in cholesterolfed ovariectomized rabbits and that two commonly prescribed progestogens do not counteract the effect. The beneficial effect of estradiol could only partly be explained by its lowering effects on serum total cholesterol or VLDL cholesterol, which implies that estradiol possesses additional beneficial effects, possibly a direct action on the arterial wall. (J. Clin. Invest.

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Section: Discussionsupporting

confidence: 94%

Estrogen monotherapy and combined estrogen-progestogen replacement therapy attenuate aortic accumulation of cholesterol in ovariectomized cholesterol-fed rabbits.

Haarbo¹,

Leth-Espensen²,

Stender³

et al. 1991

J. Clin. Invest.

199

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“…At moderate levels of serum cholesterol, the LDL was the major carrier of cholesterol (20% casein group), but at higher concentrations of serum cholesterol (40% casein group) most of the cholesterol was transported by the VLDL. These findings agree with those reported by other authors (23,24). Hypercholesterolemia in rabbits caused by feeding semipurified diets containing casein resulted in the formation of lipoprotein particles with a high ratio of cholesterol to protein, suggesting the appearance of cholesterol-rich lipoprotein particles.…”

Section: Di~usslonsupporting

confidence: 93%

The effect of different proportions of casein in semipurified diets on the concentration of serum cholesterol and the lipoprotein composition in rabbits

Terpstra

Harkes

Veen

1981

Lipids

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The effect of different proportions of casein in semipurified diets on the concentration of serum cholesterol and the lipoprotein composition was studied in rabbits. Low-casein diets (10% w/w) resulted in serum cholesterol levels and growth rates that were lower than high-casein diets (40%). An intermediate proportion of casein (20%) produced intermediate concentrations of serum cholesterol, but only minor differences in food intake and weight gain, compared with the high-casein group. In the animals with the highest values of total serum cholesterol (the 40% casein group), most of the serum cholesterol was transported in the very low density lipoproteins, whereas with moderate hypercholesterolemia (the 20% casein group), the low density lipoproteins were the main carriers of cholesterol. Elevation in lipoprotein cholesterol was associated in all groups with an increased ratio of cholesterol to protein, suggesting the formation of particles relatively rich in cholesterol. When the rabbits on the diet containing 10% casein were subsequently transferred to the 40% casein diet, a steep increase in the level of serum cholesterol occurred. Conversely, switching the rabbits on the 40% casein diet to the 10% casein diet resulted in a decrease in the level of serum cholesterol.

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“…These rabbits are incapable of increasing sterol excretion; rather, the liver secretes lipoproteins packed with an unusually large amount of cholesterol ester, and these lipoproteins have an increased residence time in the plasma as a result of downregulation of LDL receptors. Although this result appears to conflict with a number of studies reporting a primarily /3-VLDL hypercholesterolemia in the cholesterol-fed rabbit, 8 Brattsand 30 has shown that VLDL is the major carrier of cholesterol in cholesterol-fed rabbits only when TPC levels are greater than 800 mg/dL. Moreover, with increasing TPC levels (up to 1400 mg/dL), VLDL carries an increasing percentage of the cholesterol.…”

contrasting

confidence: 46%

Cholesterol-fed and casein-fed rabbit models of atherosclerosis. Part 1: Differing lesion area and volume despite equal plasma cholesterol levels.

Daley

Herderick

Cornhill

et al. 1994

Arterioscler Thromb

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One-month-old male New Zealand White rabbits were fed either a cholesterol-free casein diet (CAS; n=10); low-level cholesterol-supplemented (0.125% to 0.5% by weight) chow (CH; n=10); or standard laboratory rabbit chow (n=3) for 24 weeks, during which total plasma cholesterol (TPC) levels were matched for the two experimental groups (TPC CAS =475±39 mg/dL; TPCCH=515±70 mg/dL 2 demonstrated that the atherogenic component of the diet was cholesterol. Their pioneering experiment, in which dietary cholesterol was used to induce hyperlipidemia that resulted in atherosclerotic lesions, established the rabbit as an experimental model of atherosclerosis that is still used today. More recently, it has been discovered 3 that a cholesterol-free, casein-enriched diet induces an endogenous hypercholesterolemia that also results in atherosclerotic lesion formation.Induction of hypercholesterolemia in the rabbit with dietary cholesterol results in a very-low-density lipoprotein (VLDL) hypercholesterolemia in which the VLDL particles, enriched in cholesterol, 4 migrate as ^-lipoproteins on agarose gel electrophoresis and are thus often referred to as /J-VLDL. "7 In contrast, induction of hypercholesterolemia in the rabbit by using a semipurified diet enriched in casein results in a low-density lipoprotein (LDL) hypercholesterolemia similar to that seen in humans. 8 For this reason, the casein-fed rabbit has been used extensively in biochemical studies of lipoprotein metabolism. Only a few groups have characterized different rabbit models of atherosclerosis by using both extensive biochemical analyses and detailed morphological examinations of lesion formation.1417 However, extensive morphological evaluation including lesion area, volume, and topographic distribution has not been performed. In 1978, Ross et al 18 examined the characteristics of the casein-fed and the cholesterol-fed rabbit models to compare the effects of different lipoprotein profiles on atherosclerotic lesion formation. When animals were matched for total plasma cholesterol (TPC), the caseinfed and cholesterol-fed rabbits, although differing in lipoprotein profile, had the same extent of lesion formation. In an attempt to fully characterize the caseinfed and the cholesterol-fed rabbit models of atherosclerosis, in the present study we examined the lipoprotein profiles and the atherosclerotic lesions in the entire aorta of rabbits fed a semisynthetic diet enriched in casein and in rabbits fed a cholesterol-supplemented diet. Because the two groups were matched for TPC, we were able to examine the effect of the different lipoprotein profiles in these animals on the extent, volume, and topographic distribution of lesion formation. The relation of the lipoprotein profiles of these animals to the microscopic morphology and site specificity of lesion type is presented in the accompanying article.

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Distribution of cholesterol and triglycerides among lipoprotein fractions in fat-fed rabbits at different levels of serum cholesterol

Cited by 33 publications

References 23 publications

Estrogen monotherapy and combined estrogen-progestogen replacement therapy attenuate aortic accumulation of cholesterol in ovariectomized cholesterol-fed rabbits.

Estrogen monotherapy and combined estrogen-progestogen replacement therapy attenuate aortic accumulation of cholesterol in ovariectomized cholesterol-fed rabbits.

The effect of different proportions of casein in semipurified diets on the concentration of serum cholesterol and the lipoprotein composition in rabbits

Cholesterol-fed and casein-fed rabbit models of atherosclerosis. Part 1: Differing lesion area and volume despite equal plasma cholesterol levels.

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