ICI 182,780 acts as a partial agonist and antagonist of estradiol effects in specific cells of the sheep uterus.
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We assessed the ability of ICI 182,780 (ICI) to block the estradiol (E2) responses of genes within the sheep uterus. Ovariectomized ewes in the 'ICI+E2' treatment group received a uterine infusion with 10(-7) M ICI for 14 h, an injection of 50 microg E2 6 h after the infusion started, and were hysterectomized 18 h postinjection. Other groups received only ICI or E2, or neither treatment ('Con'). Both E2 and ICI increased the wet weight of dissected endometrium: averaging 10.0+/-1.2 g for ICI+E2, ICI, and E2 groups compared to 6.8+/-0.6 g for Con. Slot blot analyses of endometrial RNA showed that estrogen receptor-alpha (ER), progesterone receptor (PR), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), cyclophilin, actin and c-fos mRNAs responded to E2 treatment: the first five increased an average of 60% while the last decreased 38%. In situ hybridization identified more subtle ICI effects: agonistic up-regulation of GAPDH mRNA in superficial endometrial cells, and antagonistic down-regulation of ER and PR mRNAs in the inner layer of the myometrium. Thus, we conclude that the agonist versus antagonist effects of ICI relative to those of E2 are a function of the gene examined as well as the specific cell within the uterus.
J Steroid Biochem Mol Biol
author list (cited authors)
Robertson, J. A., Zhang, Y., & Ing, N. H.
complete list of authors
Robertson, JA||Zhang, Y||Ing, NH