Maternal and neonatal serum leptin levels and expression of placental leptin mRNA and their relationship to insulin concentrations in gestational diabetes mellitus

Objective: To investigate the changes in expression of placental leptin mRNA and serum leptin concentrations, and association with insulin levels in gestational diabetes mellitus (GDM). Methods: Placental tissues and maternal and neonatal blood samples were collected from 18 gestational diabetes mellitus and 20 healthy pregnant women between Oct. 1999 and Feb. 2002. Serum leptin and plasma insulin concentration were detected by radioimmunoassay (RIA). The expression of leptin mRNA in placenta were quantitated by using RT-PCR and EB-fluorescence intensity analysis. Results: In GDM group, maternal and and also the expression levels of placental leptin mRNA (P0.05). Maternal and neonatal serum leptin levels positively correlated with maternal and neonatal plasma insulin levels, respectively (r=0.53, r=0.46, P0.05) in GDM group. The significant correlations were observed between neonatal birth weight and leptin(r=0.50, P0.05), insulin (r=0.48, P0.05) concentrations in umbilical blood. Umbilical serum leptin and plasma insulin levels were strongly related to placental leptin mRNA expression(r=0.51, 0.53;P0.05). Conclusions:In GDM, both mothers and fetus have hyperleptinemia and hyperinsulinemia that may play a role as a regulator for fetal growth. There is an up-regulate action of hyperinsulinemia for placental leptin mRNA expression of GDM that may be one of the reasons of macrosomic infant in GDM.