Aim: To determine the effect of a low-dose mifepristone regimen on endometrial receptivity in guinea pigs.
Methods: Histologic evaluation for endometrial staging and immunoreactivity of cytokines [leukemia inhibitory factor (LIF) and interleukin-6 (IL-6)] were preformed on fixed endometrial tissue, and relative abundance of endometrial estrogen (E), and progesterone (P) receptor mRNA were evaluated with semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) in which cyclophilin mRNA, a housekeeping gene product, was co-amplified as the reference standard.
Results: Mifepristone at 0.03 mg.kg-1 . d-1 induced a delay in endometrial maturation. The staining intensity of LIF and IL-6 decreased in treated guinea pigs. E and P receptor mRNA increased significantly and uterine stage delayed in treated guinea pigs.
Conclusion: Mifepristone at 0.03 mg.kg-1 . d-1 delayed development of endometrium. This study provides further evidence that endometrial maturation can be altered without affecting ovarian ovulatory function.