Studies concerning the hypercholesterolemia of pregnancy: cholesterol catabolism and excretion during late pregnancy in the rat.

To investigate the mechanism of hypercholesterolemia noted in pregnancy, cholesterol catabolism and excretion was investigated during late pregnancy in the rat. Pregnancy was associated with an increase in plasma cholesterol and a decrease in the concentration of both cholesterol and bile acids in bile (with no difference in bile flows). The appearance of injected 4-C14-cholesterol in the bile of pregnant females was less than that of virgin females with a significant decrease in the bile acid fraction. The cholic/chenodeoxycholic acid ratio of newly formed C14 bile acids in pregnant rat bile was lower than in the bile of virgin female rats. Surprisingly, cholesterol balance studies failed to reveal any difference in the fecal excretion of neutral sterols or bile acids between virgin and pregnant female rats. The hypercholesterolemia of pregnancy could be partially due to the decrease in biliary cholesterol and bile acid excretion. The lack of difference in fecal cholesterol excretion is perhaps due to the operation of compensatory absorption mechanisms in the intestine which needs further investigation.