Cholesterol metabolism in serum and aorta of inbred mice fed a high-cholesterol diet.

Biochemical characterization of the serum and aorta in inbred C57BL/6Cr mice fed a high-cholesterol diet was investigated by determining the total cholesterol (TC) and free cholesterol (FC) levels in serum, high density lipoprotein (HDL) and aorta. Serum lecithin:cholesterol acyltransferase (LCAT) activity was also determined. A modified fluoroenzymatic method for microdetermination of cholesterol was successfully used. TC and FC levels of the aorta in the mice were significantly increased by the high-cholesterol diet. Serum TC and FC levels of mice fed the high-cholesterol diet were increased about 80% and 110%, respectively, compared with the control. On the other hand, both HDL-TC and HDL-FC levels were decreased about 50%. The HDL-TC/serum-TC ratio was markedly decreased, while the atherogenic index was markedly increased with the high-cholesterol diet. LCAT activity was also strikingly decreased. A positive correlation was observed between LCAT activity and HDL-cholesterol. These changes in the serum may facilitate cholesterol accumulation in the aorta. The results indicate that a biochemical approach using mice may be possible for drug evaluation.