Improvement of mouse embryo development in vitro by prolactin

Prolactin in the amniotic fluid is known to have an osmoregulatory function in the fetus, but little is known of the effects prolactin in the exudate from the endometrium acting directly on the early embryo. ICR female mice were stimulated with 6 IU of PMSG (pregnant mare serum gonadotropin) and 8 IU of hCG (human chorionic gonadotropin) and mated with ICR males. Two-cell embryos through blastocysts were obtained for in vitro culture, to which prolactin was added at doses of 0, 10, 30, 100, 300 or 1000 ng/ml. The effects of different doses of prolactin were compared for the rates of blastocyst formation and hatching, and for the development of the embryo with regards to the stage of embryo from which the culture was launched. The results show that prolactin promotes development of the two-cell embryo at concentrations of 300 ng/ml and above, improving the rate of formation of the blastocyst and hatching stages. It also has positive effects on post-hatching blastocyst cultures, in terms of acceleration in development.