The placental lactogen receptor in maternal and fetal sheep liver: regulation by glucose and role in the pathogenesis of fasting during pregnancy.

To clarify the roles of glucose and insulin in the regulation of the PL receptor in fetal and maternal sheep liver, we administered iv glucose to pregnant ewes during a 72-h fast. The binding of ovine PL (oPL) to hepatic membranes from glucose-infused ewes and their fetuses was compared with the binding of oPL to tissues of fasted, saline-infused sheep and sheep fed normally ad libitum. Fasting of pregnant ewes caused a 58-70% reduction in the number of PL receptors in fetal and maternal liver.

Placental lactogen receptors in maternal sheep liver: effects of fasting and refeeding.

In a recent study we demonstrated that fasting of the pregnant ewe reduces the number of placental lactogen (PL) receptors in fetal sheep liver. In the present study we examined the effects of a 72-h fast on the number and affinity of PL receptors in maternal sheep liver. Fasting caused a 57% reduction in the number of hepatic ovine PL receptors; this effect was reversed by refeeding.

Nutritional regulation of the placental lactogen receptor in fetal liver: implications for fetal metabolism and growth.

We have recently identified and purified from fetal liver a distinct receptor that mediates the effects of placental lactogen (PL) on amino acid transport, glycogen synthesis, and somatomedin production in fetal tissues. At present, the factors that regulate the number and affinity of PL receptors in the fetus are unknown. Since maternal nutrition plays a critical role in fetal metabolism and growth, we have examined the role of nutrition in the regulation of the PL receptor in fetal lambs.

High-density lipoproteins (HDL) stimulate placental lactogen secretion in pregnant ewes: further evidence for a role of HDL in placental lactogen secretion during pregnancy.

Previous studies from our laboratory showed that high-density lipoproteins (HDL) stimulate the release of human placental lactogen (PL) from cultured trophoblast cells from normal pregnant women. To determine whether HDL stimulates PL secretion in vivo, ovine HDL was infused over 2-5 min into 11 pregnant ewes (22 separate experiments) at 86-130 days of gestation via an indwelling catheter into the maternal jugular vein. The HDL, freshly prepared from the plasma of pregnant ewes by differential flotation ultracentrifugation, was greater than 99% purified as judged by SDS-PAGE.

A modified biophysical profile for antenatal fetal surveillance.

Three hundred thirty-seven high-risk pregnancies were screened using a modified biophysical profile consisting of nonstress testing (NST) and ultrasound evaluation of amniotic fluid volume. Ultrasound assessment of fetal breathing and body movements was performed only to evaluate the nonreactive NST. Decreased amniotic fluid volume and spontaneous fetal heart rate (FHR) decelerations were considered abnormal findings during antenatal testing, and served as indications for delivery regardless of FHR reactivity.