Leptin upregulates aquaporin 9 expression in human placenta in vitro.

Aquaporins are integral membrane proteins that have permeability functions in many tissues. Aquaporin 9 may transport not only water but also small molecules, such as glycerol, monocarboxylates, purines and pyrimidines. Aquaporin 9 is expressed in syncytiotrophoblast of human term placenta, and it may contribute to the embryonic/fetal growth and survival. We have previously found that Aquaporin 9 expression levels seem to be increased in placenta from gestational diabetes. Since leptin plasma levels and leptin expression are increased in placenta from gestational diabetes, we aimed to study the possible role of leptin on Aquaporin 9 expression in human placenta in vitro. The present work shows that leptin produces a dose-dependent increase of Aquaporin 9 expression, resulting in an increase in Aquaporin-9 protein in human trophoblast explants.