Effect of prostaglandins E2 and F2α on in vitro development and hatching of caprine blastocysts

Prostaglandin E2 has been shown to increase the ovine embryo hatching rate, and PGF2α to reduce the development of rabbit, bovine, and rat embryos. The objective was to determine the effects of PGE2 and PGF2α on development of caprine embryos. Estrus was synchronized in does (n = 25) with medroxyprogesterone acetate (MAP) intravaginal sponges for 12 days, and superovulated with 20 units of FSH. On day 6 following estrus, embryos were flushed (n = 128) and incubated individually per well in 25 μl droplets of TCM-199 and BSA (8 mg/ml) for 6 days at 38.5 °C in a 5% CO2: air with one of the following treatments: (1) control (0.0002% EtOH), (2) PGE2 (7 ng/ml), (3) PGF2α (7 ng/ml), (4) low PGE2:high PGF2α (3.5 ng/ml:14 ng/ml), (5) balanced PGE2:PGF2α (7 ng/ml:7 ng/ml), or (6) high PGE2:low PGF2α (14 ng/ml:3.5 ng/ml). Treatment with PGE2 alone reduced (P < 0.05) the hatching rate (1/15; 7%). The hatching rate of embryos treated with PGF2α alone (9/18; 50%), low PGE2:high PGF2α (8/16; 50%), and balanced PGE2:PGF2α (11/16; 69%) were similar to control (6/18; 33%). In contrast, the hatching rate was non-significantly increased (13/18; 72%) with the high PGE2:low PGF2α treatment. None of the treatments affected development from the morula to blastocyst stage. From the current data, it can be concluded that PGE2 alone reduced hatching rate, and PGF2α alone had no effect on the development of caprine embryos. High concentrations of PGE2 with PGF2α improved the hatching rates. Thus, uterine concentrations of PGE2 may need to reach a threshold level to improve embryo hatching, as previously reported, while increased uterine concentrations of PGF2α during early pregnancy would not affect development of the embryo.