Pinopode, a progesterone-dependent endometrial projection which appears during uterine receptivity period, participates in blastocyst implantation. Blastocyst loosely attaches to pinopode via L-selectin ligand (MECA-79). We hypothesized that pinopode and MECA-79 expressions were affected by testosterone. Therefore, the effect of testosterone on pinopode and MECA-79 expressions during uterine receptivity period were investigated.
Methods: Ovariectomized adult female rats received 8 days sex-steroid replacement intended to mimic hormonal changes in early pregnancy with day 6 to 8 represents uterine receptivity period. Testosterone (1 mg/kg/day) was injected together with flutamide or finasteride during the period of uterine receptivity. At the end of treatment, rats were sacrificed and uteri were removed. The existence of pinopodes in the endometrium was visualized by electron microscopy and uterine expression and distribution of MECA-79 protein were examined by Western blotting and immunohistochemistry (IHC) respectively.
Results: Abundant pinopodes and MECA-79 expressions were observed in rats received normal steroid replacement regime. Administration of testosterone during uterine receptivity period reduced pinopodes and MECA-79 expressions, which were antagonized by flutamide and not finasteride.
Conclusions: The decrease in uterine pinopodes and MECA-79 expressions during uterine receptivity period by testosterone may cause failure of blastocyst to implant in conditions associated with high level of this hormone.
Keywords: MECA-79; Pinopode; testosterone; uterine receptivity.