The Effect of Age on the Development of Hypercholesterolemia in Rabbits Fed Semipurified Diets Containing Casein

Abstract

Young and adult male rabbits were alternately fed semipurified diets and a commercial diet over a period of 57 weeks. The semipurified diets, containing either casein or soy protein, and the commercial diet were fed either ad libitum or on a restricted basis. When a restricted feeding regime was applied, both in the young and adult rabbits, significantly higher levels of serum cholesterol were observed in the animals fed casein compared with their counterparts fed soy protein. However, during the first period of feeding the semipurified diets, the hypercholesterolemic response of the casein diet was significantly greater in the young than in the adult rabbits. During the second and third period, no significant differences in cholesterolemic response were observed between young and adult rabbits fed casein diets. Further, the cholesterolemic response to semipurified diets containing casein was progressively lower during the second and third period. Similar results were found when the rabbits were fed ad libitum. However, in the adult rabbits no significant differences were observed between the rabbits fed casein and soy protein. Thus, the results of this study show that adult rabbits are less susceptible to the induction of hypercholesterolemia by feeding casein diets than are young ones.

Animal models for the atherosclerosis research: a review

“…A long-duration, low-cholesterol diet causes atherosclerotic lesions with smooth muscle cell penetration and cholesterol deposition, which are similar to that observed in human lesions (Kolodgie et al, 1996). In contrast, advanced atheromatic lesions are induced with casein, 0.2% cholesterol, and 19% butterfat provided for 6 months to 5 years Roach, 1974, 1976;Adams et al, 1982;West et al, 1982;Rogers and Karnovsky, 1988); some studies suggest that the formation of advanced lesions depends on the age of the animal. It was suggested that age is also a critical factor for the lesions, with 3-to 4.5-yearold rabbits exhibiting fibrotic plaques while young rabbits (4 months) do not (Spagnoli et al, 1991).…”

“…Indeed, different amounts of cholesterol in the diet (Bocan et al, 1993;Kolodgie et al, 1996), with or without a combination of oils (Kolodgie et al, 1996;Yanni et al, 2003) and specific proteins (Kritchevsky et al, 1977;West et al, 1982;Kritchevsky, 1995), as well as various durations of experimental studies (Hunt and Duncan, 1985;Rogers and Karnovsky, 1988), have been used to cause different types of lesions in arteries. A long-duration, low-cholesterol diet causes atherosclerotic lesions with smooth muscle cell penetration and cholesterol deposition, which are similar to that observed in human lesions (Kolodgie et al, 1996).…”

Dietary Protein as a Regulator of Lipid Metabolism: State of the Art and New Perspectives

“…It is conceivable that young , rapidly growing infants are more sensitive to the type of dietary protein than adults. The hypercholester olemic effect of casein was only observed in young growing rabbits and not in their mature counter parts (12). Indeed, Tseng et al (13) reported that the type of protein in milk formulas fed from birth had pronounced effects on serum lipids of infants in a randomized, double-blind trial (Table 1) .…”

Involvement of Post-digestion ‘Hydrophobic’ Peptides in Plasma Cholesterol-lowering Effect of Dietary Plant Proteins

“…6 ) have described how differences in animal growth affect plasma cholesterol level. For this reason, the diets used in our experiment were supplemented with their corresponding limiting amino acids.…”