RESUMO
OBJECTIVE: We investigated whether the increase of leptin expression in preeclamptic placentas is additionally influenced by soluble maternal factors under hypoxic and nonhypoxic conditions. METHODS: Term trophoblast cells were isolated and stimulated with sera from preeclamptic women under normoxic or hypoxic conditions. Levels of leptin mRNA and protein were evaluated by real-time RT-PCR or ELISA and Western blot analysis. RESULTS: Leptin concentrations were increased in the serum of patients with preeclampsia and gestational diabetes. Hypoxia, insulin, and dexamethasone induced leptin expression in trophoblast cells. The incubation with sera from preeclamptic women led to a small, though, significant, increase of leptin gene expression. The effect of preeclamptic serum on leptin gene expression in trophoblast cells was lost under hypoxia. The serum of women with gestational diabetes did not increase leptin expression neither in normoxic nor hypoxic primary trophoblast cells. CONCLUSION: Our results can not exclude a soluble maternal factor in the serum of women with preeclampsia accounting for increased leptin expression in placental tissue in addition to hypoxia. However, an important biological role of this small increase in nonhypoxic conditions does not seem very likely.