In the present investigation, we evaluated the relationship between plasma lipoprotein-cholesterol and adrenal steroid production in abortuses and newborns in whom the adrenal was expected to be atrophic, i.e. in anencephalics. We found that umbilical cord plasma levels of dehydroepiandrosterone sulfate (DS) in 23 anencephalics delivered between 13.5 and 45.5 weeks of gestation (mean ± se, 176 ± 37 ng/ml) were significantly lower than those in normal newborns of similar gestational ages; the umbilical cord plasma concentrations of cortisol in many anencephalics, however, were within normal limits. The levels of total cholesterol (134 ± 10 mg/dl) and low density lipoprotein (LDL)-cholesterol (94 ± 8 mg/dl) were substantially higher (up to 4-fold) in umbilical cord plasma of anencephalics than in umbilical cord plasma of normal newborns. The mean level of high density lipoprotein-cholesterol in umbilical cord plasma of anencephalic abortuses and newborns (38 ± 4 mg/dl) was approximately 50% higher than that in normal newborns. The lowest plasma cholesterol level (56 mg/ dl) and a concentration of DS (480 ng/ml) that was among the highest seen in the group of anencephalics were found in an anencephalic newborn in whom adrenals were of near-normal weight. Plasma cholesterol levels were inversely correlated to adrenal weights and plasma DS levels, and plasma DS levels were correlated to adrenal weight. Whereas the estimated plasma pool of DS in normal newborns increased to over 300 ng during the latter part of gestation, that of anencephalic newborns was much lower (<1 to 26 μg) and did not appear to increase as a function of gestational age. Conversely, the estimated plasma pool of cholesterol in normal newborns appeared to decline slightly during the last 10 weeks of gestation (80 mg at term), whereas that of anencephalic newborns expanded greatly near term; levels (∼200 mg) were attained that were about 3 times those in normal newborns. We conclude that the hypercholesterolemia in anencephalic newborns, due primarily to extremely elevated plasma levels of LDL-cholesterol, is a result of decreased uptake and utilization of plasma LDL-cholesterol for steroid biosynthesis by the adrenals. Since hypercholesterolemia is apparently early in gestation in anencephalic abortuses, we speculate that in normally developing fetuses, plasma LDLcholesterol is used as substrate for adrenal steroidogenesis early in gestation as well as near term when the rates of growth and steroid production by the adrenals accelerate markedly.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical