Comparison of the in vivo transcriptome of the myometrium exposed to mifepristone vs vehicle

Circulating progesterone (P4) levels decline before the onset of parturition in most animals, but not in humans. This has led to the suggestion that there is functional withdrawal of P4 action at the myometrial level prior to labor onset. However, to date, no evidence of a loss of P4 function has been provided. Mifepristone is a mixed progesterone and glucocorticoid receptor antagonist that is frequently used to induce human labor. However, its effect on the myometrial tissue transcriptome hs not been determined. In this study, we aimed to identify the effects of mifepristone treatment on the pregnant myometrium at term in order to better understand the possible mechanisms underlying the loss of P4 function in human labor. Biopsies obtained from non-laboring women at elective Caesarean section at term were dissected into 3x3x3mm^3 explants and plated in DMEM supplemented with penicillin/streptomycin. Explants were immediately treated with ethanol vehicle or 1 µM mifepristone for a period of 9 hours.