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

Journal Article · Fri Sep 01 04:00:00 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), Journal Name: Endocrinology; (USA) Vol. 125:3; ISSN ENDOA; ISSN 0013-7227
• Country of Publication: United States
• Language: English

Related Subjects

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