Nuclei Of Uterine Cells Research Articles

Apparently normal oestrogen receptor system in ovariectomized ewes with impaired response to oestrogen after prolonged grazing on oestrogenic pasture

Functional abnormalities have been observed previously in the oestrogen-responsive tissues of ovariectomized ewes with permanent infertility resulting from prolonged exposure to oestrogenic pastures. In the present study, such ewes had higher rates of protein and glycoprotein synthesis in the cervix and uterus than control ewes, but the number of oestradiol-17 beta receptors in the nucleus was similar in each group. After treatment with oestradiol-17 beta, the increase in synthesis of protein and glycoprotein in the uterus and cervix was less in clover-affected ewes, but the amount of oestradiol-17 beta-receptor complex in the nucleus of uterine cells 6 h after ewes were injected with oestradiol-17 beta was similar in clover-affected and control ewes. The rate of replenishment of oestradiol-17 beta receptors in the cytoplasm at 24 and 48 h after oestradiol-17 beta injection was also similar in both groups. The abnormal function seen in the genital tract of clover-affected ewes could not, therefore, be shown to depend on changes in oestradiol-17 beta receptors.

Neonatal stimulation of the uterus by clomiphene, tamoxifen and nafoxidine: relationship to the development of reproductive tract abnormalities.

Triphenylethylene derivatives, such as Clomid and Tamoxifen, are drugs that are in common use for the induction of ovulation and treatment of breast cancer, respectively. They are generally considered to be estrogen antagonists; however, it is well known that they may also act as agonists (15). While most investigators have been primarily interested in their antagonistic properties, we have concentrated on their estrogenic capacities. Triphenylethylene drugs cause long-term retention of the estrogen receptor in the nuclei of uterine cells and this is accompanied by a sustained stimulation of uterotropic activity (6–8, 10, 12, 17, 20, 29). This stimulation is primarily due to the ability of these drugs to stimulate the epithelium of the uterine lumen, whereas estradiol, a physiological estrogen, causes all tissues of the uterus to grow (9, 10, 17, 34). Therefore, even though these drugs are decidedly anti-estrogenic in some tissues, they are long acting estrogens in others. Since chronic exposure to estrogens is known to result in preneoplastic and neoplastic changes in the reproductive tract (22), we considered the possibility that triphenylethylene derivatives might cause such changes in the fetal and neonatal rat (5,30).KeywordsReproductive TractLuminal EpitheliumVaginal OpeningUterine LumenAtrophic OvaryThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Estrogen binding in the rat uterus: Heterogeneity of sites and relation to uterotrophic response

Multiple species of estrogen binding sites have been demonstrated in cytosol and nuclear fractions of uterine cells from immature and adult ovariectomized rats. Cytosol. Type I sites show properties identical to the classical cytoplasmic estrogen receptor. Type II binding sites have lower affinity for the ligand, exist in higher concentrations and do not undergo nuclear translocation after estrogen stimulation. These secondary sites may be involved in the retention of estrogens within the uterus, by creating an estrogen rich environment for binding to type I sites which in turn translocate estrogen as a receptor-hormone complex to the nucleus. Since it is not known whether type II sites are intra- or extracellular, they may act in this buffer capacity in either or both cellular compartments. Another possibility is that type II sites are precursors of type I sites. Nucleus. In addition to type I sites, a second site was also observed in the nuclear compartment. This second nuclear binder does not appear to be related to the cytosol type II site; however they have similar dissociation constant and share hormone and tissue specificity. Estradiol administration causes an increase in both specific binding components in uterine nuclei of mature ovariectomized rats. The second component (type II) binds estradiol with a higher capacity than type I sites, and displays a saturation curve which is sigmoidal. The stimulation of type II sites is a specific estrogenic response and is highly correlated with uterine growth. A single injection of estradiol results in long term retention of type I sites (6h), rapid and sustained elevations of type II sites (1–72 h) and true uterine growth. In contrast, estriol injection caused a rapid increase in type I sites which was not accompanied by an increase in type II sites and no true uterine growth occurred. Conversely the administration of estriol by paraffin implant sustained elevated nuclear levels of type I sites, increased nuclear type II sites 2–3 fold above controls and stimulated true uterine growth 48 h following hormone administration. These data suggest that estrogen stimulation of true uterine growth may require long term (6–24 h) nuclear retention of type I sites and sustained elevation in type II sites. These secondary sites do not appear to be translocated to the nucleus but instead may be chromosomal proteins which are present in the nucleus of uterine cells at alt times. We conclude that elevated levels of nuclear type II sites correlate well with the biosynthetic events associated with the long term uterotrophic response to estrogenic hormones.

Estrogen‐receptor binding: Relationship to estrogen‐induced responses

The relationship between nuclear binding of the receptor-estrogen complex (R-E) and estrogenic responses was examined. Nuclear-bound R-E was measured by the [3H] estradiol exchange assay, which permits the quantification of R-E as a function of either endogenous or non labeled estrogen. The quantity of nuclear R-E fluctuated as a function of blood levels of estrogen during the estrous cycle in the rat. This indicates that the accumulation of the R-E complex by the nucleus of uterine cells may be of physiologic significance and under the control of endogenous estrogen.

Estrogen receptors in the rat uterus. Retention of hormone-receptor complexes

The retention pattern and biochemical characteristics of estrogen receptors in the nuclei of uterine cells were studied as a function of time after the in vivo injection of estradiol (E2) to immature female rats. One hour after the injection of 0.1 mug of tritiated E2, approximately 0.20 pmol per uterus of receptor bound hormone is retained in uterine nuclei. This dose of E2 produces a maximal uterotrophic response. Six hours after E2 administration, uterine nuclei retain 0.04-0.08 pmol of hormone per uterus. Hormone receptor complexes extracted from uterine nuclei 1, 3, and 6 h after in vivo injection of hormone have similar structural and binding characteristics. Receptors extracted at all three times sediment at 5S in high salt gradients and have a dissociation binding constant of approximately 3 nM for E2. The wash-out curves of receptors as a function of salt concentration are identical for uterine nuclei from animals treated for 1 or 6 h with estradiol, suggesting that the nature of the nuclear binding of receptors is not altered during this time interval. Experiments utilizing the injection of unlabeled estradiol, followed by an in vitro exchange procedure with tritiated estradiol, indicated that the total nuclear estrogen receptor sites, i.e., filled and vacant, decreased similarly.

Estrogenic behavior of 2( o-chlorophenyl)-2-( p-chlorophenyl)-1,1,1-trichloroethane and its homologues

Eight chlorinated hydrocarbons were tested for their ability to compete with 3H-estradiol-17β for specific binding proteins in uterine cytoplasm from immature rats. The binding was assayed on 5–20% sucrose density gradients. 2( o-Chlorophenyl)-1,1,1-trichloroethane (o,p′-DDT) and 2( o-chlorophenyl)-2-( p-chloropenyl)-1,1-dichloroethylene (o,p′-DDE) (1·4 × 10 −4M) competed with 3H-estradiol-17β (8·7 × 10 −9 M) for binding to the “8 S receptor” in the cytomplasm. 2,2-Bis-( p-chlorophenyl)-1,1,1-trichloroethane (p,p′-DDT), 2,2-bis-( p-chlorophenyl)-1,1-dichloroethylene (p,p′-DDE), 2,2-bis-( p-chlorophenyl)-1,1-dichloroethane (p,p′-DDD), 2( m-chlorophenyl)-2-( p-chlorophenyl)-1,1-dichloroethane (m,p′-DDD), 2( o-chlorophenyl)-2-( p-chlorophenyl)-1,1-dichloroethylene (o,p′-DDD) and bis-( p-chlorophenyl)-1,1-dichloroacetate (DDA) did not compete at 1sd4 × 10 −4 M. Transfer of the receptor-bound compounds into the nuclei was examined using similar competition techniques. o,p′-DDT and o,p′-DDE competed with estradiol binding in the nuclei. These studies indicate that o,p′-DDT and o,p′-DDE at high concentrations act as estrogens as measured by their ability to compete with estradiol-17β for binding to the uterine cytopoasmic receptor and in the transfer and binding of estradiol in the nuclei of uterine cells.

Effect of superfusion with human male serum, bovine serum albumin or non radioactive estrogens on the retention of tritiated estradiol-17β and estriol by the rat uterus

Slices of mature rat uterus were superfused with either tritiated estradiol-17β or estriol, and subsequently superfused with different washing solutions. The retention of the labeled steroids by the nuclei of glandular and deep stromal cells and by the eosinophils was studied using a dry radioautographic technique for soluble compounds. Superfusion with a washing solution containg non-radioactive estradiol-17β partially displaces either tritiated estradiol-17β or estriol from the nuclei of uterine cells. Superfusion with a washing solution containing either human male serum, bovine serum albumin, or non-radioactive estradiol-17β or estriol partially extracts tritiated estradiol-17β from the uterine eosinophils. Superfusion with a washing solution containing either non-radioactive estradiol-17β or estriol partially displaces tritiated estriol from the uterine eosinophils. Non-radioactive estradiol-17β displaces more label from the nuclei of uterine cells than does non-radioactive estriol, especially when the tracer used is tritiated estriol. On the contrary, nonradioactive estriol displaces more radioactivity from the eosinophils than does non-radioactive estradiol-17β, especially when the tracer is tritiated estradiol-17β. These results suggest that there is some exchange of receptor-bound estrogens with exogenous estrogens for both the cytosol-nuclear and the eosinophil binding systems, and that the cytosol-nuclear and the eosinophil binding systems differ in regard to their retention of estradiol-17β and estriol.