Hormonal regulation of neonatal weight: placental leptin and leptin receptors.
OBJECTIVE
To examine whether umbilical and maternal leptin levels correlate with birthweight, placental weight, and maternal weight; and to detect membrane-bound leptin receptors in placental tissue as well as soluble leptin receptors in umbilical and maternal blood.


METHODS
Prospective observational study.


METHODS
University teaching hospital.


METHODS
Serum levels of leptin and soluble leptin receptors were analysed in 31 randomly selected mother/newborn pairs at delivery. In addition, placental tissue was assayed for leptin receptors using immunocytochemistry and Western blot.


RESULTS
The mean [SD] leptin level in umbilical cord venous blood (7.1 ng/mL [4.0]) was significantly lower (P<0.001) than in maternal blood (22.5 ng/mL [10.8]). Umbilical cord leptin concentrations correlated significantly with birthweight (P<0.001), placental weight (P<0.005) but not with maternal leptin. Maternal leptin concentrations correlated only with maternal weight (P<0.001). In chorionic villous tissue, trophoblasts stained strongly positive for leptin receptor-like immunoreactivity. Two membrane-bound isoforms of the leptin receptor were also detected in placental tissue. In both umbilical and maternal serum, a soluble leptin receptor was found migrating as broad band at Mr 97,000 D.


CONCLUSIONS
The present data strongly reinforce the idea that circulating leptin levels may provide a growth-promoting signal for fetal development during late pregnancy. While membrane-bound leptin receptors may be involved in autocrine regulation of placental leptin production, the soluble receptor form may serve as a transport vehicle for leptin to fetal tissues.
Schulz
S
S
Department of Obstetrics and Gynaecology, Otto-von-Guericke University, Magdeburg, Germany.
Häckel
C
C
Weise
W
W
D000328:Adult; D001724:Birth Weight / Q000502:physiology; D015153:Blotting, Western / Q000379:methods; D001835:Body Weight / Q000502:physiology; D002352:Carrier Proteins / Q000097:blood*; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D020738:Leptin / Q000097:blood*; D010920:Placenta / Q000737:chemistry*; D011247:Pregnancy; D011446:Prospective Studies; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin
D002352:Carrier Proteins; C515448:LEPR protein, human; D020738:Leptin; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin