A high resolution SEM study of the effects of RU486, used as a postcoital contraceptive, on the rat uterus during early pregnancy (original) (raw)
Related papers
Endocrinology, 1997
Oxytocin (OT) and its receptor (OTR) are synthesized in the endometrium and myometrium of the pregnant rat during late gestation. Both are regulated by estrogen and progesterone (P 4), and tissue concentrations of both increase markedly before parturition. The P 4 antagonist RU486 will induce parturition in the rat. The purpose of the present studies was to investigate changes in OT and OTR messenger RNA (mRNA) and peptide synthesis within the pregnant rat uterus during RU486-induced parturition. Pregnant rats were given a single injection of RU486 (2.5 mg/rat in oil) on day 15 of pregnancy (normal delivery occurs on day 22). Control animals received injections of oil only. Groups of animals (n ϭ 5 in each group) were euthanized at 0, 6, 12, 24, and 48 h after injection and during labor (immediately after delivery of the first pup). Maternal serum estradiol (E 2), P 4 and uterine OT, and PGE 2 concentrations were measured by RIA. Prostaglandin F 2␣ and estrogen receptor levels were measured by enzyme immunoassay (EIA).
Biology of Reproduction, 1996
The objective of the present study was to examine the effects of the antiprogesterone RU486 on the expression levels of multiple gap junction (GI) gene products and, in detail, on a, (con-nexin43 [Cx43]), in various regions of the rat implantation chamber during experimentally induced preterm labor at mid/ late stages of gestation. Vaginal bleeding, but not expulsion of concepti, was observed in a majority of animals 24 h after a single injection of RU486 at Day 15 of gestation, and it persisted until animals were killed 48 h later. The bleeding was completely suppressed by R 5020, a synthetic progesterone with a high affinity for the progesterone receptor (PR). Various components of the implantation chamber (uterus, mesometrial stroma, placenta) and ovaries were isolated 24 and 48 h postinjection and analyzed for a, (Cx43), 13 (Cx32), and 132 (Cx26) connexin expression by immunohistochemistry and by Northern blots (a, only). a, Connexin was present at high levels in the myometrium following the inhibition of progesterone action by RU486; accordingly, this effect was completely suppressed by R 5020. The blocking of the PR also had a dramatic effect on expression levels, size, and distribution of junctional plaques composed of , and 132 connexins in polarized luminal and glandular epithelium. The average size of junctional plaques was significantly reduced in the luminal epithelium after RU486 administration. This effect was inhibited in the presence of R 5020. At the RNA level, the a, transcript was markedly elevated in the uterus and in the ovaries 24 and 48 h after administration of RU486. An elevation was also observed in the mesometrial stroma, while no increase was detected in the placenta. The RU486-induced a, mRNA steady-state levels in various tissues were completely suppressed by R 5020. These results demonstrate the modulation of multiple connexins in various cell types of the implantation chamber upon blocking of PR action. The expression profile of the myometrial and epithelial GJs was similar to that previously observed in the estrogen-treated rat uterus.
PubMed, 1992
The authors show here that progesterone suppresses apoptosis, and its antagonist RU 486 induces it in rabbit uterine epithelium, as assessed by morphologic and biochemical studies. The authors' studies demonstrate that internucleosomal DNA fragments are identifiable as early as 24 hours after ovariectomy of pseudopregnant rabbits, and become undetectable 6 days after ovariectomy. Maximal levels of DNA fragmentation (about 74% of total isolated DNA) were observed 36 hours after ovariectomy. The number of apoptotic cells appeared to increase parallel to the increased DNA breakdown, and accounted for approximately 26% of the uterine epithelial cells at 48 hours after ovariectomy. Levels of progesterone in serum dropped precipitously 6 hours after ovariectomy and remained very low for several days. Administration of progesterone, more than any other steroid hormone, to pseudopregnant ovariectomized rabbits, prevented the increase in apoptotic cell death. By contrast, administration of the anti-progestin RU 486 to pseudopregnant rabbits triggered apoptosis, which attained levels similar to those observed in ovariectomized animals. The authors' findings establish that uterine epithelium apoptosis occurs in a time-dependent fashion and provides strong evidence that the actions of progesterone in that tissue are not only to stimulate cell proliferation and differentiation, but also to suppress apoptosis.
The effect of RU486 on the gene expression profile in an endometrial explant model
Molecular Human Reproduction, 2003
Administration of RU486 in vivo during the receptive phase rapidly renders the endometrium non-receptive to the implanting embryo. In order to identify key pathways responsible for endometrial receptivity we have used cDNA arrays to monitor gene expression changes in short-term endometrial explants in response to RU486. Endometrial biopsies from ®ve normal fertile women at mid-secretory phase were cultured in the presence of estradiol and progesterone with or without RU486 for 12 h. cDNA arrays were produced containing~1000 sequence-veri®ed clones which included genes known to be important in angiogenesis, apoptosis, cell signalling, extracellular matrix remodelling and cell cycle regulation. cDNA probes from the paired endometrial samples were hybridized to the arrays and hybridization signals were quanti®ed. A total of 12 genes displayed signi®cant changes in expression; six were up-regulated and six down-regulated following RU486 treatment. For ®ve of these genes this is the ®rst report suggesting that they are regulated by steroids in the endometrium. JAK1 and JNK1 were two of the genes shown by the arrays to be down-regulated in RU486-treated endometrial explants. This was con®rmed by real time RT±PCR. JAK1 immunoreactivity was localized to both glandular epithelium and the stroma of normal endometrium and staining was much stronger in the luteal phase of the cycle. These results show that components of two important signalling pathways in endometriumÐthe JAK/STAT pathway, and the JNK pathwayÐare altered by RU486. Genes whose expression is controlled by these pathways are likely to be involved in the mechanism by which steroids render the endometrium receptive to the implanting embryo.
Human Reproduction, 1996
The characteristics of implantation stage endometrium following a single-dose, early luteal phase application of mifepristone (RU486) in proven conception cycles has been examined in the rhesus monkey in an attempt to understand the physiological basis of the anti-implantation activity of the drug. Endometrial samples were collected from monkeys subjected to vehicle (group 1, n = 14) and RU486 (2 mg/kg body weight; group 2, n = 12) on day 2 after the presumed day of ovulation of successfully mated cycles. The average diameter of glands (P < 0.05), number of vacuolated cells (P < 0.01), number of supranuclear vacuolated cells (P < 0.05) in glandular epithelium and amount of glandular secretion {P < 0.05) were significantly lower in RU486-treated endometrium compared with control tissue samples. Additionally, 18% of glandular epithelial cells showed apoptotic and degenerative features in RU486-treated tissue samples. These data, together with the observed significant decreases in precipitate area (P < 0.02) and hi the optical absorbance of alkaline phosphatase reaction end-product (P < 0.05), confirm that retardation in glandular differentiation in the upper functionalis is a likely target of antiprogestin action hi implantation stage endometrium. An increased frequency of mitosis hi stromal cells (P < 0.05) and a greater degree of extravasation (P < 0.05) were also observed after RU486 exposure. Despite an apparent indication of constriction and regression in few RU486-exposed endometria compared with controls, morphometric analyses did not show any changes in capillary structure. Whether endometria] vasculature hi progesterone-exposed uterus is a target of antiprogestin action during the peri-implantation stage remains to be determined. Further studies are required to explain the observed increase (P < 0.02) hi the area of precipitate of von Willebrand (vW) factor with no change hi vW factor-positive vessels, and the apparent increase hi collagen IV immunostain in subepithelial and perivascular basement membrane in implantation stage endometrium after early luteal phase RU486 treatment hi monkeys.
Domestic Animal Endocrinology, 2014
This study was designed to determine whether inhibition of either cyclooxygenase-2 (COX-2) by indomethacin or progesterone receptor (PR) by PR antagonist, RU486, affects oocyte maturation, progesterone production, and covalent binding between hyaluronan (HA) and heavy chains of inter-a trypsin inhibitor, as well as expression of cumulus expansion-associated proteins (HA-binding protein, tumor necrosis factor a-induced protein 6, pentraxin 3) in oocyte-cumulus complexes (OCCs). The experiments were based on freshly isolated porcine OCC cultures in which the consequences of PR and COX-2 inhibition on the final processes of oocyte maturation were determined. Granulosa cells (GCs) and OCCs were cultured in medium supplemented with FSH/LH (both 100 ng/mL) in the presence/absence of RU486 or indomethacin. Western blot analysis, 3 H-glucosamine hydrochloride assay, immunofluorescence, and radioimmunoassay were performed. Only treatment with RU486 (25 mM) caused a decrease in the number of oocytes that reached germinal vesicle breakdown and metaphase II stage compared with indomethacin (100 mM) or FSH/LH treatment alone after 44 h. All treated OCCs synthesized an almost equal amount of HA. Heavy chains (of inter-a trypsin inhibitor)-HA covalent complexes were formed during in vitro FSH/LH-stimulated expansion in RU486-or indomethacintreated OCCs. Follicle-stimulating hormone/LH-induced progesterone production by OCCs was increased in the presence of RU486 after 44 h. In contrast, a decrease of FSH/LHstimulated progesterone production by GCs was detected in the presence of either RU486 or indomethacin after 72 h. We suggest that the PR-dependent pathway may be involved in the regulation of oocyte maturation. Both PR and COX-2 regulate FSH/LH-stimulated progesterone production by OCCs and GCs.
2012
Objective: To investigates the effect of mifepristone (anti-progesterone) on stromal cells of the uterus of rats. Study Design: Laboratory based randomized controlled trials Method: Sixty adult female rats were divided randomly into two groups, comprising of 30 animals in each group. In-group A 1ml of normal saline was given orally daily for three months while in group B mifepristone was given orally in a dose of 1mg/kg body weight daily for three months. All the animals were sacrificed next day after the last oral dose. 2ml blood was taken directly from the heart for measurement of progesterone levels. Sections were stained with hematoxylin and eosin for light microscopic study. Immunohistochemical staining procedure was done for demonstration of progesterone receptors Results: The stromal cells were flattened and irregular in outline present around the glands. Some appeared fusiform or spindle shaped. In the experimental group the stromal cells were tightly packed. There was an increase in the number of infiltration of granulocytes and eosinophils in the stroma. Progesterone antagonist application lowered the plasma concentration of progesterone. The number of progesterone receptors in all uterine compartments of the experimental group were decreased and found statistically significant. Conclusion: In conclusion, mifepristone affects stromal, glandular and epithelial morphology in the rat uterus.