The effect of eifferent estrogen‐progesterone ratios on DNA synthesis in the rat uterus

摘要

AbstractThe influence of different estrogen‐progesterone ratios on DNA synthesis in the rat uterus was investigated. Ovariectomized rats were injected subcutaneously daily for three days with either oil, 1 μg estradiol‐17β dipropionate or estradiol and 1, 5, 10 or 15 mg progesterone. Tritiated thymidine was administered one hour prior to necropsy. Thymidine indices were determine for both the luminal and glandular uterine epithelia while the total number of labeled nuclei in the stroma was ascertained. In all tissues studied, significantly more nuclei from uteri of rats given only estrogen replicated DNA than from those of the oil‐treated controls. While concurrent treatment with estradiol and 1 or 15 mg progesterone did not statistically alter the extent of thymidine incorporation in the luminal epithelium and stroma from that observed following estrogen alone, 5 or 10 mg progesterone given with estrogen significantly suppressed the labeling activity in the luminal epithelium and stroma from that of the estrogen‐treated rats. However, the thymidine indices of the glandular epithelium from uteri of rats injected with all combinations of both hormones were significantly lower than that from uteri of estrogen‐treated rats. These data indicate that the estrogen–progesterone ratio is important in regulating cell turnover in the luminal epithelium and stroma of the rat uterus but not in glandul