Hiroko Mise

A positive umbilical venous-arterial difference of leptin level and its rapid decline after birth☆☆☆★★★

OBJECTIVE We investigated the site of leptin production in the fetoplacental circulation. STUDY DESIGN We simultaneously determined plasma leptin levels in cord vessels and maternal peripheral veins of 38 healthy pregnant women. We also compared plasma leptin levels in 20 neonates at birth and on the fifth day after birth. RESULTS Leptin levels in cord vessels were significantly (p < 0.001) lower than those in maternal veins (mean 29.5 ng/ml). Leptin levels in umbilical arteries (mean 9.8 ng/ml) were significantly (p < 0.01) lower than those in umbilical veins (mean 12.9 ng/ml). Leptin levels in neonatal veins on the fifth day (mean 3.0 ng/ml) were markedly (p < 0.001) lower than those in umbilical arteries of the same neonates (mean 10.9 ng/ml). CONCLUSION The higher leptin levels in umbilical veins than in umbilical arteries and the marked decrease during the neonatal period suggest that the placenta is one of the major sources of leptin in the fetal circulation.

Leptin as a novel placenta-derived hormone in humans

Summary These studies provide the first evidence for leptin as a novel placenta-derived hormone in humans, and suggests the physiologic and pathophysiologic significance of leptin in normal pregnancy and in pregnancies complicated with preeclampsia or gestational trophoblastic diseases. To elucidate the role of leptin in human pregnancy, further investigations on the following points are required. o 1. Mechanism of resistance to high plasma leptin levels during pregnancy has not been elucidated. Studies on down-regulation of leptin receptor and changes in the plasma concentrations of leptin binding protein, which is identical to soluble leptin receptor, Ob-Re, may provide an answer to this question. 2. Possible candidates of the biological significance of placenta-derived leptin in pregnancy may be; a) effects on maternal glucose and lipid metabolism, b) regulation of placental function, and c) effects on fetal growth and development. 3. Identification of distribution of leptin receptors in intra-uterine tissues is crucial to understand the role of placenta-derived leptin during pregnancy.