| Abstract
| - BACKGROUND: Recently we discovered that the human oviduct synthesizes abundant prostacyclin (PGI2). Gene knock-out studies suggest that PGI2 is essential to endometrial decidualization, but the effects of PGI2 on sperm and embryos have not been reported. METHODS: The effects of PGI2 on human sperm were analysed by a computer-assisted semen analysis system. The effects of PGI2 on mouse embryos were examined based on the rates of complete hatching. The expression of PGI2 receptor (IP) was evaluated by Western blot analysis and immunohistochemistry. The binding of PGI2 to embryos was confirmed by radioligand binding assay. Finally, cAMP levels were assessed in PGI2-challenged embryos. RESULTS: Iloprost (a stable PGI2 analogue) did not affect the motility or the overnight survivability of human sperm. Western blot analysis did not detect IP in the sperm plasma membrane. In contrast, the hatching of mouse embryos was enhanced by iloprost (ED50 6.7 nmol/l). Exposure to iloprost during 8-cell to morulae or morulae to early blastocyst stages was critical to enhanced hatching. This coincided with the developmental stage-specific expression of IP. Although iloprost bound to blastocysts, it did not significantly increase cAMP. CONCLUSION: PGI2 enhanced the hatching of mouse embryos but not the motility of human sperm.
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