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

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Endocrinology; (USA)

DOI:https://doi.org/10.1210/endo-125-3-1504· OSTI ID:5546495

Freemark, M; Comer, M; Mularoni, T; D'Ercole, A J; Grandis, A; Kodack, L ^[1]

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1. Duke Univ. Medical Center, Durham, NC (USA)

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. Pregnant ewes at 123-126 days gestation were fed ad libitum (FED), fasted for 3 days (FASTED), or fasted for 3 days and then refed for an additional 3 days (REFED). The ewes were then killed, and the binding of (125I)ovine (o) PL to hepatic microsomes from the fetal lambs was examined. Maternal fasting caused a 60-75% reduction in the specific binding of oPL to fetal liver; the effect of fasting was reversed in part by refeeding. The decrease in oPL binding resulted from an 80% reduction in the number of fetal oPL-binding sites (Scatchard analysis); there were no changes in the affinity of the oPL receptor (Kd, 0.6 nM), the subunit structure of the receptor, or the degree of occupancy of the receptor in vivo by endogenous fetal hormones. The specific bindings of GH (0.6%), PRL (0.3%), and insulin (35%) to fetal liver were not affected by maternal fasting, indicating that caloric restriction exerted a specific effect on oPL binding in the fetus. The number of fetal oPL-binding sites was positively correlated with the fetal liver glycogen content (r = 0.69; P less than 0.01) and the fetal plasma concentrations of glucose (r = 0.68; P less than 0.01) and insulin-like growth factor-I (r = 0.74; P less than 0.001), suggesting a role for the PL receptor in the regulation of fetal carbohydrate metabolism and growth.

• OSTI ID: 5546495
• Journal Information: Endocrinology; (USA), Vol. 125:3; ISSN 0013-7227
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBOHYDRATES
METABOLISM
FETUSES
ANIMAL GROWTH
LACTOGENS
RECEPTORS
BIOCHEMICAL REACTION KINETICS
GLUCOSE
GLYCOGEN
IODINE 125
LIVER
MICROSOMES
MOLECULAR WEIGHT
NUTRITION
PREGNANCY
SHEEP
TRACER TECHNIQUES
ALDEHYDES
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DOMESTIC ANIMALS
ELECTRON CAPTURE RADIOISOTOPES
GLANDS
GROWTH
HEXOSES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MONOSACCHARIDES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
POLYSACCHARIDES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RIBOSOMES
RUMINANTS
SACCHARIDES
VERTEBRATES
550501* - Metabolism- Tracer Techniques