Association Between Progesterone Receptor Expression In Human Placenta Chorionic Tissues And Labor Onset

Objective:we designed a series of experiments to find the existence and location of progesterone receptor (PR) in placenta villous tissues and disscuss the relationship between PR expression and labor onset .Methods: PR protein levels and cellular localization were measured by immunohistochemistry and Western blot, respectively, in term pregnancy placenta tissue .Two clinical groups were selected:woman in labor(n=15)and not in labor (n=15).Results: 1. PR immunostaining in placenta tissue not in labor was positive, and slightly positive in placenta tissue in labor. 2. Western blot revealed that there were two kinds of PR expression in placenta villous tissue :PR-A(84KD) and PR-B(114KD). PR-B level was lower in labor group vs. no labor group(p<0.01), with a gray scale value of 9.58±1.01, 16.21±1.274,respectively. And PR-A level was also lower in labor group vs. no labor group(p<0.01), with a gray scale value of 1.62±0.591, 2.71±0.799, respectively. The PR-A to PR-B protein ratio was 0.48±0.075 in no labor tissues and was increased to 0.59±0.124 in labor group,(p<0.05).Conclusions: 1. There are PR-A,PR-B expression in placenta villous tissues. 2. An increased PR-A to PR-B ratio may participate in the process of labor onset.