Reciprocal expression of peroxisome proliferator-activated receptor-γ and cyclooxygenase-2 in human term parturition

Objective The objective of this study was to test the hypothesis that peroxisome proliferator activated receptor-γ (PPAR-γ) is expressed in intrauterine tissues before active term human parturition, and that its repression is associated with up-regulation of cyclooxygenase-2 (COX-2). Study Design Specimens were collected from women with term singleton pregnancies after spontaneous labor or cesarean section before labor, prepared for immunoblot and immunohistochemical analysis, and probed for PPAR-γ or COX-2. Results PPAR-γ expression was prominent in fetal membranes and placenta before active labor. After labor, PPAR-γ expression was significantly reduced in fetal membranes, but not in placenta. The ratio of COX-2:PPAR-γ was significantly elevated in fetal membranes with labor. PPAR-γ immunostaining was prominent in syncytiotrophoblast, extravillous cytotrophoblasts, and cells of the amnion and chorion. COX-2 immunostaining was abundant in the amnion and rare in the placenta. Conclusion PPAR-γ is highly expressed in term intrauterine tissues. In fetal membranes, PPAR-γ levels are reduced once active labor commences, coincidental with a relative increase in COX-2 expression.