Effects of PGF2α and indomethacin on ovulation and steroid production in the isolated perfused rabbit ovary

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Abstract
Both ovaries of 31 rabbits were perfused with a chemically defined medium in vitro in a recirculation system. In 1 series of experiments, hCG [human chorionic gonadotropin] (100 IU) was injected i.v. 5-6 prior to anesthesia and surgery. Approximately 1 h later the perfusion was started. One ovary was perfused as control while the other ovary was perfused with 5 .mu.gml indomethacin or with indomethacin and 1 .mu.g/ml PG[prostaglandin]F2.alpha.. In another series of experiments the rabbits recieved no pretreatment prior to operation. Instead, bovine LH [luteinizing hormone] was added to the perfusion medium of both control and experimental ovaries. The experimental side also received either indomethacin or indomethacin and PGF2.alpha.. The effect of PGF2.alpha. in the absence of LH was compared to the control ovary receiving only LH. After injection of hCG in vivo, ovulations occurred in 4 of 5 control ovaries. Indomethacin completely blocked ovulation in 4 of the 5 ovaries treated, while PGF2.alpha. restored ovulations in all the experimental ovaries. In the group of experiments where LH was added in vitro, ovulations were induced in all ovaries treated with varying LH doses. Furthermore, indomethacin blocked ovulation in 5 out of 7 ovaries, and PGF2.alpha. (in the absence of LH) also ovulated. The pattern of steroid release did not differ between control ovaries, indomethacin treated ovaries, and indomethacin + PGF2.alpha. treated ovaries. Ovaries treated in perfusion with PGF2.alpha. alone had very low steroid levels compared to the ovaries treated with LH. Indomethacin blocks ovulation in the perfused rabbit ovary and this blockade can be overcome by exogenous PGF2.alpha.. Indomethacin and PG-treatments after ovulation induction did not affect ovarian steroidogenesis. While PGF2.alpha. was able to induce ovulations in these perfused estrous ovaries in the absence of LH, it did not stimulate steroidogenesis.