Relationships between dietary cholesterol, cholesterol absorption, cholesterol synthesis, and plasma cholesterol in rhesus monkeys.

The relationships between the cholesterol content of the diet, plasma cholesterol concentration, cholesterol absorption, and cholesterol synthesis (measured indirectly by desmosterol suppression technique) are explored in groups of high- and low-responding rhesus monkeys fed diets containing 0.02, 0.15 and 0.75 mg cholesterol/kcal. The cholesterol content of the diet (expressed as mg/kcal) is positively correlated with plasma cholesterol concentration and is negatively correlated with percent cholesterol absorption in both groups. Also the cholesterol content of the diet is negatively correlated (r = -0.66) with cholesterol synthesis only in low-responders but not in high-responders. Similarly, the correlation between percent cholesterol absorption and cholesterol synthesis is significant in the low-responders (r = 0.82, P less than 0.01) but not in the high-responders (r = 0.12, P greater than 0.1). Further, a negative correlation (r = -0.61) is observed between cholesterol synthesis and plasma cholesterol concentration in the low-responders but in the high-responders, there is no relationship between the parameters. From these correlations we conclude that the higher cholesterol absorption in the high-responders than in the low-responders is one important mechanism responsible for the development of severe hypercholesterolemia in the high-responding monkeys fed cholesterol. The results also suggest that there might be a lower sensitivity in the feedback inhibition mechanism of cholesterol biosynthesis in the high-responding than in the low-responding rhesus monkeys.