Differential Response of Individual Uterine Cell Types from Immature Rats Treated with Estradiol*

Abstract

The separation of viable epithelial, stromal, and myometrial cells from immature rat uteri is described. The integrity of the separated cells was established by their ability to grow in culture and to exclude trypan blue and by transmission and scanning microscopy. Epithelial preparations contain insignificant contamination by other cells. Stromal fractions are estimated to contain 10% epithelial contamination. Myometrial fractions probably contain significant contamination by stroma, but the amount is difficult to quantify. The three cell types separated from untreated rats or from rats treated with 17 beta-estradiol (E2) differ from each other physiologically. Control epithelial cells incorporated more tritiated cytidine per microgram DNA than stromal or myometrial cells. 17 beta-Estradiol enhanced incorporation of tritiated cytidine into RNA of epithelial cells but not stromal or myometrial cells. RNA to DNA ratios of cells from untreated rats were 1.0 (epithelial), 0.5 (stromal), and 0.6 (myometrial). RNA to DNA ratios rose approximately 30% in all cell types after E2. Estrogen receptor (ER) concentrations, determined by Scatchard analysis under exchange conditions, also differed in the three cell types. Nuclear ER concentrations (as measured in crude nuclear fractions) were significantly higher (P less than 0.01) in epithelial and stromal cell fractions from untreated animals than in the myometrial fraction, i.e. 5.5, 3.8, and 1.2 fmol/microgram DNA, respectively. The chief effect of E2 administration was a significant increase (P less than 0.05) in cytosol ER of all cell types. Epithelial cells had the highest cytosol ER concentration, increasing from 0.5 to 3.1 fmol/microgram DNA 48 h after E2 administration. Although the myometrial cells had the lowest ER concentration, they contained 84-89% of the entire uterine ER by virtue of the proponderance of myometrium in the whole uterus. The differing responses of epithelial and stromal cells, therefore, are diluted or masked by the ER content of the myometrium in assays of whole uterus. Although the total number of ER sites in the cytosol and nucleus (16,900-32,100 sites/cell) in separated stromal cells at various times after E2 stimulation was similar to ER concentrations (20,000-30,000 sites/cell) previously reported for the whole uterus, the partition of ER between cytosol and nucleus (10:90) was different, favoring the nucleus even before E2 administration. ER began to appear in increased amounts in the cytosol only 24 h post E2 administration. When tritiated E2 was given in vivo and its specific binding was assessed in the uterine cells subsequently separated, ER partition between cytosol and nucleus was also heavily in favor of the nucleus. However, when whole uterus was assayed, the partition of ER between cytosol and nucleus (90:10) was exactly the opposite. Possible reasons for this unusual finding are discussed.

Effect of diethylstilbestrol on cell proliferation and expression of epidermal growth factor in the developing female rat reproductive tract

“…However, such patterns in prenatal rodents are not well understood. Similarly, 17 -estradiol effects on reproductive tract cell proliferation have been well reported in immature and adult rodents (McCormack & Glasser 1980, Quarmby & Korach 1984. However, -fetoprotein limits fetal 17 -estradiol exposure in utero.…”

“…EGF and insulin-like growth factor (IGF)-I stimulate cell proliferation in immature mouse uterine and vaginal epithelial cells in vitro (Tomooka et al 1986, Iguchi et al 1987, Shiraga et al 1997. Because estrogen stimulates uterine epithelial cell proliferation (McCormack & Glasser 1980, Quarmby & Korach 1984 and expression of EGF, IGF-I, heparin-binding EGF-like growth factor, transforming growth factor (TGF)-and EGF-R in the reproductive tracts of mice and rats, these growth factors may mediate the estrogen-induced proliferative and differentiative responses in rodent reproductive tracts (Murphy et al 1987, DiAugustine et al 1988, Nelson et al 1991, Beck & Garner 1992, Ignar-Trowbridge et al 1992, Kapur et al 1992, Das et al 1994, Sahlin et al 1994, Zhang et al 1994, Falck & Forsberg 1996, Hom et al 1998. In the fetal reproductive tract, expression of EGF-R in mice (Bossert et al 1990), and EGF, TGFand IGF-I in rats (Koike & Noumura 1993, Kanno et al 1994, Gu et al 1999) was reported.…”

“…In female fetuses, Müllerian duct development and Wolffian duct degeneration occur due to a lack of androgens and MIS after gonadal differentiation (Josso & Picard 1986). The pattern of cell proliferation in the female reproductive tract has been demonstrated in immature and adult rodents (McCormack & Glasser 1980, Quarmby & Korach 1984, Li 1994. However, such patterns in prenatal rodents are not well understood.…”

Oestrogen increases S-phase fraction and oestrogen and progesterone receptors in human cervical cancer in vivo

“…We also observed that oestrogen administration caused the induction of its own receptor. This phenomenon has not been widely recognized in humans, although oestrogen-stimulated induction of its own receptor has been reported in several animal models (McCormach and Glasser, 1980;Sutherland et al, 1980;Lessey et al, 1981). Piva et al (1988) have demonstrated an increase in ER mRNA in human breast cancer cell lines cultured with oestradiol.…”

Oxysterol Nuclear Receptor LXRβ Regulates Cholesterol Homeostasis and Contractile Function in Mouse Uterus

“…The endometrium, located in the inner part of the organ, is the site of blastocyst implantation, and its epithelium undergoes cyclic radical changes under the control of ovarian sex steroid hormones (1); estrogens are responsible for epithelial cell hyperplasia, whereas progesterone blocks cell proliferation and induces differentiation. The myometrium (2), in the outer part of the uterus, accounts for more than 60% of the whole organ (3) and has a primordial role in uterine function. Whereas muscle quiescence due to high progesterone levels is essential during most of the pregnancy (4), efficient myometrium contractility is fundamental for a normal labor (for a review, see Ref.…”