Progesterone and oestradiol receptor concentration and translocation in uterine tissue of rabbits treated with indomethacin.

The purpose of this study was to determine whether endogenous prostaglandins are involved in the regulation of sexual steroid receptor concentration and cytosol to nucleus translocation in the rabbit uterus. The animals were injected s.c. with indomethacin (10 mg/kg) twice daily on days 5 and 6 and on the morning of day 7 of pregnancy or pseudopregnancy and killed 2 h after the last injection. The indomethacin treatment did not change progesterone and oestradiol serum concentrations compared with animals injected with vehicle only. No differences were observed either in progesterone receptor or oestradiol (pregnant animals only) receptor concentration and intracellular distribution in endometria of indomethacin-treated or control animals. In an extended experiment indomethacin given to oestrogen-pretreated ovariectomized rabbits did not inhibit the nuclear progesterone receptor accumulation induced by a single progesterone injection. These results suggest that there is no direct relationship between prostaglandins and sexual steroid receptors in the rabbit uterus.