The expression and regulation of aquaporins in placenta and fetal membranes.

Previous studies by our group as well as other researchers have found expression of Aquaporins (AQPs) 1, 3, 8, and 9 in human chorioamniotic membranes and placenta. Our previous study found that the alteration of the expression of AQPs 1, 3, 8, and 9 in placenta and fetal membranes was an adaptive response to maintain amniotic fluid homeostasis in case of abnormal amniotic fluid volume, which is likely to affect the intramembranous absorption and transport of water and solute from mother to fetus. However, the actual regulation mechanisms of intramembranous absorption and placental water flow are not yet clear, making it difficult to treat abnormal amniotic fluid volume effectively. Several studies found that many factors, including hormone levels, osmotic pressure, temperature, and oxygen concentration, regulate expression of AQPs in placenta, fetal membranes, and other mammalian organs through several signal transduction pathways, such as the cAMP, the MAPK, the PI3K/AKT, and the PKC pathways. These factors could provide potential therapeutic targets for the treatment of abnormal amniotic fluid volume.