Aquaporin 1 gene deletion affects the amniotic fluid volume and composition as well as the expression of other aquaporin water channels in placenta and fetal membranes

Objective: To explore the role of aquaporin 1 (AQP1) in regulation of amniotic fluid volume and composition. To investigate the effects of AQP1 gene knockout on expression of other aquaporin water channels (AQP3, AQP8 and AQP9) in placentas and fetal membranes. Methods: Mice were sacrificed at 9.5, 13.5 and 16.5 gestational day (GD). Amniotic fluid volume, osmolality and composition, fetal membranes, placental and fetal weights as well as placenta areas were recorded in Aqpl homozygote conceptus group, heterozygote conceptus group and wild-type group, respectively. The expression of AQP1, AQP3, AQP8 and AQP9 mRNA and protein in placenta and fetal membranes were examined by quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting. Results: Aqpl homozygote conceptus had a greater volume of amniotic fluid, lower osmolality and calcium concentration than their wild -type counterparts at 16.5 GD. There was no significant difference in expression of AQP1, AQP3, AQP8 and AQP9 in placentas among three groups. While expression of AQP8 was increased at 13.5 and 16.5 GD in fetal membranes, the expression of AQP9 was significantly decreased in fetal membranes in Aqpl homozygote group compared with Aqpl heterozygote and wild-type groups. Conclusion: AQP1 may play an important role in the homeostasis of maternal-fetal fluid at late gestation days. The mechanism of mutual compensation among AQPs gene needs further investigation.