Cholesterol feeding effect

Malinow, M.R., McLaughlin, P., Naito, H.K., Lewis, L.A., and McNulty, W.P. 1978. Effect of alfalfa meal on shrinkage (regression) of atherosclerotic plaques during cholesterol feeding in monkeys. 

Vuoristo, M. and Miettinen, T.A. 1994. Absorption, metabolism, and serum concentrations of cholesterol in vegetarians Effects of cholesterol feeding. Am. J. Clin. Nutr. 59, 1325-1331. 

PURPOSE AND RATIONALE Rabbits are known to be susceptible to hypercholesterolemia and arteriosclerosis after excessive cholesterol feeding (supplemented with 0.3-2% cholesterol in the diet). Therefore, this approach has been chosen by many authors to study the effect of potential anti-atherosclerotic drags. For studying the atherogenic potential of a candidate compound a low cholesterol concentration in the diet (0.1-0.3%) is recommended (pro-atherogenic). 

The answer is d. (Murray, pp 258-297. Scriver, pp 2705-2716. Sack, pp 121-138. Wilson, pp 362-367.) Regulation of cholesterol metabolism is by definition exerted at the committed and rate-controlling step. This is the reaction catalyzed by 3-hydroxy-3-methylglutaryl CoA reductase. Reductase activity is reduced by fasting and by cholesterol feeding and thus provides effective feedback control of cholesterol metabolism. The statin class of drugs act at this site. 

Figure 1. Effect of nifedipine on the extent of aortic lesions (planimetry of sudano-philic lesions) induced by cholesterol feeding. Key (n = 13) , placebo and [3,...

Pools A and B also appear to be functionally distinct with respect to the role of the sterol in these pools to effectively regulate the rate of cholesterol synthesis within the intestinal epithehal cell. For example, cholesterol feeding in the rat and in man... 

HMG-CoA reductase is also subject to translational control by a mevalonate-derived non-sterol regulator (D. Peffley, 1985 M. Nakanishi, 1988). Tliis component of the regulatory mechanism can be observed only when cultured cells are acutely incubated with statins, which block mevalonate formation. Under those conditions, sterols have no effect on HMG-CoA reductase mRNA translation however, mevalonate reduces the HMG-CoA mRNA translation by 80% with no change in mRNA levels. Translational control of hepatic HMG-CoA reductase by dietary cholesterol was shown in an animal model in which polysome-associated HMG-CoA reductase mRNA was analyzed in cholesterol-fed rats (C.M. Chambers, 1997). It was found that cholesterol feeding increased the portion of mRNA associated with translationally inactive monosomes and decreased the portion of mRNA associated with translationally active polysomes. The mechanism of HMG-CoA reductase translational control has not been elucidated. 

Cholesterol feeding has no effect on the amount of mRNA for HMG-CoA reductase. The actin mRNA is a positive control to (1) verify that RNA can be effectively recovered from all samples, and (2) allow normalization of the results, if necessary, to correct for variations in the extent of overall RNA recovery from sample to sample. The amount of HMG-CoA reductase protein is greatly reduced when the animals are fed a cholesterol diet. 

Influence of the fatty acid composition of the diet on the effect of cholesterol feeding... 

The experiments described above on the effect of cholesterol feeding were performed with an EFA (essential fatty acid) sufficient diet using corn oil as fat supplement and were interpreted as a consequence of the modification of the membrane fluidity due to cholesterol "condensing effect". The effect of cholesterol feeding on the kinetic parameters of membrane-associated enzymes was further investigated using different fat supplemented diets. 

Table 6. Effect of cholesterol feeding on n values of acetylcholinesterase and ATPase from rats fed diets...

When the effect of cholesterol feeding on the Arrhenius plot was investigated, it was found (Bloj et al., 1976b) that, in the case of the enzyme from rats fed corn oil-plus-cholesterol supplemented diet, a curve with two breaking points, one at 20 C and another at 29 C, was obtained (Fig. 4). After solubilization of... 

Beneficial effects of vitamin C supplementation observed both when supplementation provided in conjunction with cholesterol feeding or only after three weeks of cholesterol feeding. Supplementation with vitamin C (1 or 4 g/kg diet) for eight weeks increased plasma levels to 162.4 22.1 and 261.2 51.1 xM in cholesterol-fed rabbits, compared with 67.3 12.5 and 44.3 6.2 xM for nonsupplemented cholesterol-fed rabbits, respectively. 

Cholesterol absorption during bile acid feeding Effect of ursodeoxycholic (UDCA) administration. Gastroenterology, 78 214 (1980). 

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