Development of cholesterol metabolism: the effect of diet composition at weaning

Wistar rats were weaned on day 18 to a high fat (HF), high carbohydrate (HG) or high cholesterol (HCO 2%) diet. The activities of 3-hydroxy-3-methylglutaryl-CoA-reductase (HMGR), 7 alpha-hydroxylase (7-OHase) and acyl-CoA-cholesterol-acyltransferase (ACAT) were assayed in the liver and small intestinal mucosa on days 21, 25 and 30 and in adult animals. An HF diet raises hepatic ACAT and HMGR activities in young rats but has the opposite effect in the gut. The cholesterol diet also raises hepatic ACAT activity, but less so than the HF diet. In the gut, however, the HCO diet invokes the greatest rise in ACAT of all the diets tested. Except in adult rats, the HG diet always raises hepatic ACAT activity more than the HCO diet or the Purina Chow. In the gut, however, activity is very low for the HG diet, much lower than for the HCO diet. Early feeding of the HCO diet for 12 days (from day 18 to 30) and refeeding the same diet from day 48 to 50 resulted in a subsequent response to the HCO diet. It is concluded that early weaning results in changes in enzyme activities that depend on the composition of the diet fed at weaning and that this may also effect the later response to the same and perhaps other diets.