Effects of dietary cholesterol level and type of dietary carbohydrate on hepatic and plasma sterols in the gerbil.

The influence of dietary cholesterol and type of carbohydrate on the level of free cholesterol, esterified cholesterol, and the type of cholesteryl esters in the liver of the Mongolian gerbil, Meriones unguiculatus, was studied by a series of experiments. Semipurified diets were fed in which the level of cholesterol was comparable to human intakes (0.1% by weight) or higher (0.5%) and the carbohydrate source was starch or sucrose or a mixture there of. All diets were devoid of bile acid and contained relative amounts of carbohydrate, protein, fat, and type of fat which approached human intakes in North America. Free cholesterol levels in liver were 60-140% greater and 15-30% greater when diets were supplemented to contain sterol levels of 0.5 and 0.1%, respectively, whereas hepatic cholesteryl ester levels were 11- to 23- fold greater and 2- to 3-fold greater, respectively. Levels of cholesterol (both free and esterified) in plasma were 175-725% greater in animals consuming 0.5% dietary cholesterol and 30-105% greater in gerbils ingesting 0.1% cholesterol as compared with levels in gerbils fed a basal (unsupplemented) diet. The type of dietary carbohydrate had a moderate influence on cholesterol levels in liver and plasma when dietary cholesterol was supplied at 0.5%. The percent contribution of 18:1 fatty acid to the liver cholesteryl esters was greater in cholesterol-supplemented gerbils, while the proportions of 16:0 and 18:2 acids were lower. These results indicate that the gerbil is highly sensitive to low levels of dietary cholesterol in diets which are also free of bile acid, in contrast to many other species, including the laboratory rat. The present findings support the usefulness of the gerbil model for studying the influence of dietary sterol on cholesterol metabolism.