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Biomedical subjects

L Aftergood

Publications and source records attributed to L Aftergood.

24 records · Page 2Linked to original sources
PubMed1968

Effect of large doses of the oral contraceptive Enovid on cholesterol metabolism in the rat.

Short-term effects of the oral contraceptive drug, Enovid, a mixture of estrogenic and progesterone compounds, have been determined in experiments on male and female rats. Oral administration of large doses for 7 days resulted in marked decreases of cholesteryl esters in plasma accompanied by only slight elevations of hepatic cholesterol content. Cholesteryl esters were also much lower in adrenals and ovaries, organs which are usually responsible for steroid hormone biosynthesis. At the same time, cholesterol-esterifying activity in plasma was substantially increased. Enovid administration was shown also to affect the fatty acid composition of sterol esters remaining in plasma, adrenals, and ovaries. The concentration of linoleate and arachidonate was significantly decreased in plasma sterol esters, whereas the concentrations of arachidonate and docosatetraenoate in adrenals and of docosatetraenoate in ovaries were significantly lowered. All of the changes reported were more pronounced in the female than in the male rat. It is hypothesized that the decreased levels of cholesteryl ester found in the organs investigated, together with the increase in plasma cholesterol-esterifying activity, are probably associated either with changes in cholesterol biosynthesis and(or) transport or with an increase in cholesterol transformation to other steroids and excretion. These possibilities are now under investigation.

Adrenal Glands↗
PubMed1967

Sex differences in plasma cholesterol-esterifying activity in rats.

Esterification of free cholesterol was investigated after incubation at 37 degrees C of plasma from immature and adult rats of both sexes kept on stock, fat-free, or cholesterol-supplemented diets. According to measurements of the decrease in free cholesterol, plasma from the fat-deficient rats showed the highest cholesterol-esterifying activity. Esterification was higher in the mature female rats than in the mature males on stock or cholesterol-containing diets, although no sex differences were observed in the sexually immature young or in the fat-free animals. There were no sex differences in the fatty acid composition of the plasma sterol esters, phospholipids, and triglycerides in the immature animals, but arachidonic acid increased at the expense of linoleic acid in the sterol ester fraction in the adult female (not, however, in the adult male). In the phospholipid fraction the higher ratio of palmitic to stearic acids in the male was confirmed. There was an increase in linoleic acid in all three plasma lipid fractions of the mature male after cholesterol feeding. It is suggested that cholesterol may inhibit the conversion of linoleate to arachidonate. During the incubation of plasma, there was little change in the distribution of fatty acids except for a decrease in palmitoleate, and increases in C(20) tri- and tetraenoic acids, in the sterol esters of mature female rats on the stock ration and the fat-free diet. These C(20) acids decreased concomitantly in the phospholipid fraction, as the transesterification reaction mechanism proposed by earlier workers would predict.

Animals↗