Progesterone synthesis by the human corpus luteum requires a source of
cholesterol, which can be derived from both local synthesis and uptake of
low density lipoproteins (
LDL). When the corpus luteum is maintained in organ culture,
progesterone synthesis is primarily dependent on
LDL and the rate of
progesterone production during growth in a
LDL-free media is suboptimal. An in vivo situation analogous to that of corpus luteum grown in
LDL-depleted media exists naturally in patients with
abetalipoproteinemia. To determine whether a complete deficiency of plasma
LDL affects serum concentrations of
progesterone (particularly during the luteal phase) or those of other
hormones, we have measured the serum concentrations of
luteinizing hormone,
follicle-stimulating hormone,
prolactin,
estradiol,
estrone, and
progesterone during the menstrual cycle in a patient with phenotypic
abetalipoproteinemia (on the basis of homozygous
hypobetalipoproteinemia). Our results show a normal cyclical pattern with midcycle increases in the concentrations of luteinizing and follicle-stimulating
hormones,
prolactin, and
estrogens but a distinctly subnormal increase in the luteal phase concentrations of
progesterone. These results suggest that, in patients with phenotypic
abetalipoproteinemia, the absence of
LDL leads to an impairment in the maximal rates of production of
progesterone by the corpus luteum.