Abstract
We examined the activities of intestinal acyl-CoA: cholesterol acyltransferase (ACAT) and cholesterol esterase, enzymes regulating cholesterol absorption, in rats with streptozotocin-induced diabetes to clarify the effect of diabetes on cholesterol absorption. Three weeks after the induction of diabetes, plasma cholesterol levels were slightly increased in diabetic rats compared with controls, whereas a remarkable increase in plasma cholesterol was observed in diabetic rats fed a 1% cholesterol diet. Microsomal ACAT activity in intestinal mucosa was 3 times higher in diabetic than in control rats. However, no significant difference in the enzyme activity could be detected between diabetic animals fed control chow and those fed the cholesterol diet. Furthermore, insulin supplementation given to diabetic rats caused a reduction of enzyme activity to the levels found in controls. In contrast, cholesterol esterase activity in rat intestinal mucosa was unaffected by either the induction of diabetes or cholesterol feeding. These data indicate that enhanced cholesterol absorption via a CoA-dependent esterification process in the intestine might be one of the major factors responsible for hypercholesterolemia in diabetes.
