Effect of cyclic 3 ',5 '-adenosine monophosphate, glucocorticoids, and insulin on leptin messenger RNA levels and leptin secretion in cultured human trophoblast

Leptin is a polypeptide hormone originally thought to be produced exclusive ly by adipocytes. However, both leptin mRNA and leptin protein were identif ied in human placental trophoblast cells, suggesting a potential role in hu man pregnancy. In the present report, we examined the regulation of leptin mRNA levels and secretion by cAMP, glucocorticoids, and insulin in term hum an placental tissue. Placentae were obtained immediately after delivery fro m mothers with uncomplicated pregnancies. Leptin concentrations were measur ed by ELISA in the cultured media of trophoblast maintained in monolayer cu lture for 24, 48, and 72 h. Likewise leptin mRNA levels in these cultured h uman trophoblast cells were determined by reverse transcription-polymerase chain reaction. Treatment with forskolin and (Bu)(2) cAMP led to a time- an d dose-dependent increase in leptin release, significant after 48 and 72 h. Moreover, incubation with forskolin for 48 h also clearly increased leptin mRNA concentration. Leptin secretion and mRNA levels were also assessed af ter treatment with insulin or dexamethasone. We found a time- and dose-depe ndent increase in leptin release, significant after 48 and 72 h. Leptin mRN A levels were also increased after these treatments. All this supports a st imulatory role of cAMP pathway, insulin and dexamethasone in the leptin mRN A levels, and leptin release in trophoblast cells in vitro.