Effect of lactation on cholesterol synthesis in rats
Feingold, K.R.; Moser, A.H.
American Journal of Physiology 249(2 Pt 1): G203-G208
1985
ISSN/ISBN: 0002-9513 PMID: 4025547 Document Number: 243024
Lactation induces a variety of morphological and functional changes in the gastrointestinal tract. Tritiated water was used as the substrate to demonstrate that in the intact rat lactation results in a 2-fold increase in cholesterol synthesis in the small intestine. Feeding a high-cholesterol diet did not markedly inhibit small intestinal cholesterol synthesis in either control or lactating animals, and the difference in cholesterol synthesis between the 2 groups persisted. In the large intestine, cholesterol synthesis is increased 3-fold in the lactating animals, and feeding a high-cholesterol diet did not affect synthesis in either the control or lactating animals. In the liver, lactation stimulated cholesterol synthesis and quantitatively this increase in hepatic cholesterol synthesis is much greater than the increase observed in the intestines. Feeding the rats a high-cholesterol diet markedly inhibited hepatic cholesterol synthesis in both control and lactating animals, a finding that demonstrates that the feedback inhibition of cholesterol synthesis in the liver is not impaired by lactation. In the lactating animals, the quantity of labeled cholesterol in 1 ml of serum is 2.4 times greater than observed in controls. Feeding the rats a high-cholesterol diet markedly decreased the quantity of labeled cholesterol in the serum in both groups and obliterated the difference between control and lactating animals. The increased hepatic cholesterol synthesis in the lactating animals is responsible for the differences in labeled cholesterol in the serum. Cholesterol feeding also reduced the quantity of labeled cholesterol localized to the mammary glands in lactating animals. Cholesterol synthesis is increased in the liver, small intestine, and large intestine of lactating animals.