Investigation of necessity of sodium cholate and minimal required amount of cholesterol for dietary induction of atherosclerosis in microminipigs.

Recently we established a Microminipig (MMPig) model of atherosclerosis induced by high fat/high cholesterol (Cho) diet containing sodium cholate (SC), which is known to cause hepatotoxicity. In the present study, we investigated whether SC is necessary as well as the minimum amount of dietary Cho required to induce atherosclerosis. Experiment A: Six MMPigs were divided into three groups of two, and were fed for 12 weeks as follows: a diet containing 12% fat and 5% Cho with or without 0.7% SC, or the diet including 12% fat and 0.5% Cho with SC. Although each diet induced a similar degree of hypercholesterolemia and atherosclerosis, the liver weights and severity of fatty change in the hepatocytes were maximal in the animals fed 5% Cho and SC. Experiment B: Six MMPigs were divided into two groups of three, and fed for 18 weeks as follows: normal diet, and a diet of increasing dose of Cho (0.03, 0.1, 0.3, 0.5, 1.5 and 5%) for the initial 14 weeks and 0.5% Cho/12% fat diet for the final four weeks. Serum levels of total Cho and low-density lipoprotein-Cho reached a plateau with 0.5% Cho diet, suggesting that the minimum amount of Cho required is 0.5%. The absorption of Cho in MMPigs was enhanced by 0.5% Cho and 12% fat diet compared to the 5% Cho-alone diet. In conclusion, a diet with 0.5% Cho and 12% fat without SC appears to be sufficient to induce atherosclerosis in the MMPig.