Cholesterol metabolism in obese mice.

Young male obese mice and their lean litter mates (strain ob/ob) were compared. Serum cholesterol levels were higher in obese than in lean animals. 3-Hydroxy-3-methylglutaryl-CoA reductase activity was lower in brown adipose tissue and liver of obese mice than in tissue from their lean litter mates. However, activity of this enzyme was found to be the same or higher in white adipose tissue of obese animals than in their lean litter mates. During complete starvation, blood cholesterol levels in obese mice decreased and attained the lower level of lean ones after 48 h. After 24 h of starvation, enzyme activity decreased in white fat of obese mice only. Simple calculations indicate that white fat from obese mice produces about fourfold more cholesterol per day per unit body weight than does the same tissue from lean mice.