Placenta and fetal membrane play an important role in maternal-fetal homeostasis. However, the molecular and cellular mechanisms underlying water transfer across placenta and amniotic membrane remain unknown. It is hypothesized that maternal-fetal fluid exchanges via aquaporin (AQP) water channels in the placenta and fetal membrane.OBJECTIVE:
To investigate AQP8 protein expression in normal human placenta and fetal membrane.DESIGN, TIME AND SETTING:
A control observation was performed at the Central Laboratory of Guangzhou Medical College from July to December 2005.MATERIALS:
Human placenta and fetal membrane tissues from 5 elective cesarean section deliveries of normal term pregnancies (range 37-42 weeks) were studied. Maternal age averaged (27±5) years old. Experimental protocol was approved by the Hospital's Ethics Committee.METHODS:
Thirty minutes after delivery, fetal membrane and placenta were dissected and washed with sterile physiological saline. Some were frozen at −80°C, and the remaining tissues were fixed for 24-48 hours with 10% neutral formalin and paraffin embedded for immunohistochemical staining.MAIN OUTCOME MEASURES:
AQP8 expression and distribution in human placenta and fetal membrane were detected by the reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blotting analysis.RESULTS:
RT-PCR results showed that AQP8 mRNA was expressed in both placenta and fetal membrane tissues. Western blotting analysis also yielded positive results in placenta and fetal membrane with a specific band site at approximately 45 000. Immunohistochemistry results revealed that AQP8 protein was expressed in placental syncytiotrophoblasts, amniotic epithelial cells, and chorion cytotrophoblasts.CONCLUSION:
At protein level, AQP8 is expressed in placental syncytiotrophoblasts, amniotic epithelial cells, and chorion cytotrophoblasts.