Effects of androgen on embryo implantation in the mouse delayed-implantation model

Objective: To examine the effects of androgen on implantation and decidualization in the mouse delayed-implantation model. Design: Experimental animal study. Setting: University research laboratory. Animal(s): Sexually mature female mice (Kunming White strain). Intervention(s): Delayed and activated implantation; pseudopregnancy; embryo transfer (ET): E-2 assay, inhibitor. Main Outcome Measure(S): Effects of androgen on embryo implantation were determined by treating the mice under delayed implantation with different doses of testosterone propionate (TIP); the effects of androgen on the expression of implantation-related genes were examined by in situ hybridization. Result(S): Delayed implantation could be initiated by TP. Dihydrotestosterone was also able to initiate implantation in the delayed-implantation model. The implantation window could be maintained for at least 48 hours by 5 1 mg TP per mouse. Prostaglandin endoperoxide synthase 2 (Ptgs2) and microsomal prostaglandin E synthase (mPtges) were aberrantly expressed in mouse uterus at implantation sites after delayed implantation was activated by high doses of TP. Conclusion(S): A low dose of TP led to a delay in embryo implantation, but a high dose caused aberrant expression of both Ptgs2 and mPtges at the implantation site. It is possible that high doses of TP may disturb peri-implantation development or may be involved in early pregnancy loss by disturbing the uterine prostaglandin system.