Hormonal control of uterine growth: alterations in luminal epithelial deoxyribonucleic acid synthesis after intraluminal application of estrogen.

Administration of a single injection of estradiol (E2) causes a maximum increase in DNA synthesis in the uterine luminal epithelium approximately 24 h later. We previously reported that animals receiving a second injection of E2 15-18 h after the first show an apparent decrease in DNA synthesis measured in this cell type at 24 h. This apparent decrease in DNA synthesis is due to a shift in the time course of DNA synthesis rather than an absolute decrease in this parameter. In this report we demonstrate that this inhibitory effect of a second injection of E2 is also observed after intraluminal instillation of the hormone. This effect is dose dependent and appears to result from a shift in the time course of luminal epithelial DNA synthesis. The intraluminal instillation of E2 produces the same pattern of nuclear receptor localization as sc administration of the hormone. These results suggest that this inhibitory effect we previously described results primarily from a direct action of E2 on the luminal epithelium.