Differential expression of adenosine receptors in normal and preeclamptic human placentas

Kim, Young Han; Cho, Nam Hoon; Hwang, Han Sung; Kwon, Ja Young; Kang, Myoung Hwa; Park, Yong Won

Abstract

OBJECTIVE
The aim of the study was to investigate the differential expression of adenosine receptors (ADORs) in the normal and preeclamptic placenta.
METHODS
Placentas were obtained from women undergoing cesarean section with normal and preeclamptic pregnancies at term. Total RNA was reverse transcribed using ADORs gene specific primers. RT-PCR measurements were made semi-quantitatively. Western blot analysis was performed for protein quantitation. Immunohistochemical staining with anti-adenosine receptor antibodies were employed to localize adenosine receptors in placental tissues.
RESULTS
RT-PCR revealed that A2aR, A2bR, and A3R mRNA, not A1 receptor mRNA were expressed in both normal and preeclamptic placenta. Interestingly, there were somewhat higher expressions of A2aR, A2bR, and A3R mRNA in preeclamptic placenta than in normal placenta. Western blotting revealed that A2a, A2b, and A3 receptors were all present in the placental tissue as verified by immunoreactive protein bands. The bands for the A2a, A2b, and A3 receptors were stronger in preeclamptic placenta than in normal placenta. A2a and A2b receptors were detected in endothelial cell, whereas we could not find the staining for A3 receptor in endothelial cells. Importantly, A3 antibody had high intensity of staining in trophoblasts in preeclampsia.
CONCLUSION
To our knowledge, this study is the first to evaluate the expression of ADORs in normal placenta, and to compare ADOR subtypes in normal versus preeclamptic placenta. This study suggests that the specific subtype of ADORs may have a role in the development of preeclampsia.