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Abstract
Leukaemia inhibitory factor (LIF) is a pleiotropic cytokine previously demonstrated to be essential for blastocyst implantation in mice. Samples of endometrium from normal cyclic women throughout the menstrual cycle were tested for LIF messenger RNA by Northern blot analysis and the corresponding protein was localised immunohistochemically with a polyclonal antibody to LIF. Western blot analysis detected a 45 kDa LIF protein in an extract from late secretory tissue. The expression of LIF messenger RNA transcript was detected only during the mid and late secretory phases of the cycle after day 20. Immunoreactive LIF was observed in all human endometrial samples. In the stroma there were moderate to high levels of immunohistochemical staining throughout the cycle with considerable variation between individuals but no cyclical variation. Epithelial staining, both luminal and glandular, was also present throughout the cycle but this was relatively low in the proliferative phase and strongest in the mid to late secretory phases. The marked cyclical changes of immunoreactive LIF in the human endometrial epithelium suggest a paracrine/autocrine role for LIF in endometrial function. Whether LIF is essential for implantation in the human remains to be established.
Journal of Endocrinology (1996) 148, 95–102
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SUMMARY
Cytoplasmic and nuclear oestradiol-17β binding sites have been measured in human endometrium obtained at different stages of the menstrual cycle and from patients with cystic hyperplasia and endometrial carcinoma. In normal endometrium both sets of sites are maximal at about the time of ovulation. The number of nuclear sites obtained by incubating endometrium with oestradiol-17β in vitro paralleled the number of available cytoplasmic sites.
Cytoplasmic and nuclear binding sites were present in cystic hyperplasia and endometrial carcinomata. There was no correlation between the degree of differentiation of the tumour and its oestradiol-17β binding capacity. All types of endometrium contained variable amounts of 8–10 S and 4–5 S cytoplasmic receptors. The proportions of these receptors were not affected by the presence of the protease inhibitor, p-phenylmethylsulphonyl fluoride.
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SUMMARY
Tissue concentrations of glycogen and incorporation of leucine and uridine were measured after short-term organ culture of human endometrium. Higher concentrations of glycogen and an increased rate of incorporation of leucine were found in tissue from cultures treated with oestrogen and progesterone when compared with tissue from cultures treated with oestrogen alone. No detectable difference in uridine incorporation was observed in these experiments.
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SUMMARY
Solid intrauterine implants of certain steroids were made in prepubertal and adolescent ovariectomized and oestrone-primed rhesus monkeys. Implants of the following steroids produced localized progestational changes in the endometrial glands: progesterone, deoxycortone, ethisterone, testosterone, methyl testosterone and methyl dihydrotestosterone. Pregnenolone produced only minimal progestational effects. Pregnanediol showed no progestational effect and failed to maintain the endometrium.
A comparison of the direct progestational action of a number of steroids on the endometrium has been made in the four species so far investigated (mouse, rabbit, cat and monkey, each of which represents a different mammalian order). Direct progestational action requires a fairly close structural similarity to progesterone in all cases, but the degree of similarity required shows a marked species difference.
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SUMMARY
A technique in which uterine luminal epithelium is separated from the remainder of the endometrium by rapidly vibrating everted uterine cornua in a 3·5 mm solution of EDTA has been developed. Examination of the hormonal sensitivities and physiological roles of the tissue components of the endometrium is thus facilitated.
Biochemical and histochemical studies of epithelial, stromal and endometrial esterases have shown that the rate of hydrolysis of α-naphthyl acetate is significantly higher in epithelial and endometrial tissue extracts during pro-oestrus than at any other stage of the oestrous cycle. In ovariectomized animals, oestradiol-17β caused a 60% increase in the rate of esterase activity over that of control animals, whereas medroxyprogesterone acetate had no effect. These findings suggest that the variations in the levels of neutral lipids in the uterine luminal epithelium of non-pregnant mature female rats result from the periodic stimulation of the epithelial esterases by the cyclically increased levels of plasma oestrogens.
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Department of Obstetrics & Gynecology, The Memorial Hospital, Worcester, Massachusetts, and *Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545, U.S.A.
(Received 14 January 1975)
Evans & Hähnel (1971) and Trams, Engel, Lehmann & Maass (1973) have reported that during the endometrial proliferative stage of the human menstrual cycle oestrogen-binding capacity is high, but during the secretory stage of the cycle, when progesterone is the dominant ovarian hormone, oestrogen-binding capacity is reduced. Sucrose density gradient analysis of human uterine cytosol has demonstrated oestradiol-17β-binding components sedimenting at 5 S (Wyss, Heinrichs & Herrmann, 1968) or 4 S and 8 S (Martin, 1972) although in neither study was the cycle time of the tissue reported.
Evans & Hähnel (1971) found that bound oestradiol-17β was located in the endometrium and the present study was undertaken to determine the presence or absence of the 8 S oestrogen-binding component in human endometrium during the menstrual cycle.
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ABSTRACT
Pig conceptuses display a surge in oestrogen and catecholoestrogen synthetic activity during the periimplantation period. However, the pathways of catecholoestrogen metabolism in pig conceptuses and endometrium are unknown. O-Methylation is an important route of catecholoestrogen metabolism. Therefore, the O-methylations of 2- and 4-hydroxy-oestradiols (2- and 4-OH-oestradiol) by cytosol of pig conceptuses and endometrium during the periimplantation period were studied. Kinetic studies performed in tissues obtained on day 13 of pregnancy (day 0 = first acceptance of the male) indicated that the O-methylation of 2-OH-oestradiol displayed simple Michaelis–Menten kinetics in both tissues. In blastocysts, the apparent Michaelis constant (K m) and maximum velocity (V max) for the O-methylation of 2-OH-oestradiol were 1·4 μmol/l and 11·27 pmol/mg protein per min respectively, and when 4-OH-oestradiol was used as substrate, the values were 2·53 μmol/l and 9·86 pmol/mg protein per min respectively. The apparent K m and V max values for the O-methylation of 2-OH-oestradiol in endometrium were 0·77 μmol/l and 19·6 pmol/mg protein per min respectively, and for the O-methylation of 4-OH-oestradiol were 2·44 μmol/l and 10·38 pmol/mg protein per min respectively. Ontogenesis of catechol-O-methyltransferase (COMT) in conceptuses and endometrium was studied from day 10 to day 19 of pregnancy. Conceptus COMT activity was lowest on day 10 and increased gradually to day 19 of pregnancy. Because a surge of oestradiol-2/4-hydroxylase activity occurs on days 11–13, less COMT activity on these days than on the later days of pregnancy is consistent with a role for catecholoestrogens in conceptus-maternal signalling during pregnancy establishment. Endometrial COMT activity on day 10 was higher than that on later days of pregnancy. Therefore, a role for COMT in modulation of catecholoestrogen and oestrogen function during the peri-implantation period is possible.
Journal of Endocrinology (1990) 127, 77–84
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ABSTRACT
The endometrium of late pregnant guinea-pigs was found to contain mRNA for relaxin. Poly(A)+RNA hybridized to 3 2P-labelled porcine relaxin-specific oligonucleotide probes. These probes corresponded to the C-peptide region of the prohormone. There was no hybridization to a 3 2P-labelled probe to the B-chain of porcine relaxin even under conditions of low stringency. The size of the relaxin mRNA was approximately 1.0 kb and similar to that found for relaxin mRNA from the pregnant sow ovary. This is the first study on relaxin mRNA from a uterine source.
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Abstract
Endothelin-1 (ET-1) is present in ovine endometrium, primarily in epithelial cells, and increases around the time of implantation. We examined the cell type expressing ET-binding sites in vitro and whether ET-1 has mitogenic actions in the endometrium, alone or in synergy with other growth factors. Purified epithelial and stromal cells were prepared from luteal-phase endometrium. Specific receptors were demonstrated by binding of 125I-ET-1 and proliferative effects of ET-1 and/or other growth factors determined by uptake of [3H]thymidine by cells in serum-free culture. 125I-ET-1 bound to both epithelial (2516 ± 820 c.p.m./well) and stromal (6368 ± 1350 c.p.m./well) cells and was displaced by ET-1 (1 μmol l−1). There were no proliferative effects of ET on epithelial cells. ET-1 (10 nmol l−1) stimulated uptake of [3H]thymidine by stromal cells under serum-free conditions in 13/20 individual cell preparations, to 149 ± 13% of control (untreated=100%) with dose-dependence between the range of 1 to 100 nmol l−1. Stimulation by fetal calf serum was to 377 ± 126% of control. The effects on proliferation by other growth factors (dose; % of control ± s.e.m., number of positives/total number of cell preparations) were: IGF-I (13 nmol l−1; 182 ± 14, 4/4), epidermal growth factor (EGF; 4·8 nmol l−1; 132 ± 5%, 7/7), platelet-derived growth factor-BB (0·4 nmol l−1; 146 ± 3, 2/2) and leukaemia inhibitory factor (0·4 nmol l−1; 110 ± 2, 3/3). All stimulations except that of EGF were significant and dose-responsive but only insulin was additive with ET (350 ± 35, 5/5). ET-1 also stimulated expression of the the AP-1 cis element c-jun, this being maximal at 60 min of exposure to mitogen. ET-1, along with other growth factors has a likely paracrine role in cellular proliferation in the endometrium, possibly in association with blastocyst implantation.
Journal of Endocrinology (1997) 152, 283–290
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ABSTRACT
Human endometrium contains specific binding sites for iodinated endothelin (ET)-1, ET-2 and ET-3, and ET-1 stimulates prostaglandin (PG) F2α synthesis from explants of proliferative endometrium in short-term culture. This study has investigated the cellular responses of normal proliferative endometrium to ET-1. Radioimmunoassay was used to measure PG release and Dowex anion-exchange column chromatography was utilized to assess the accumulation of inositol phosphates. Endothelin-1 induced a significant increase in PGF2α release (basal median: 1465 pg/mg per 60 min (range: 541–3935 pg/mg per 60 min); ET-1-stimulated: 1813 pg/mg per 60 min (1021–5714 pg/mg per 60 min); P < 0·04 using Wilcoxon signed rank test). The effect of ET-1 was attenuated in the presence of the phospholipase A2 inhibitor quinacrine. Endothelin-1 induced a rapid, transient and concentration-dependent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), measured by the accumulation of tritiated inositol phosphates. Following a 1-min stimulation with ET-1 (100 nmol/l), [3H]inositol mono-, bisand trisphosphate fractions increased from median values of 490·0 d.p.m./mg dry wt (range: 348·0–807·0 d.p.m./mg dry wt), 120·0 d.p.m./mg dry wt (93·6–144·1 d.p.m./mg dry wt) and 67·0 d.p.m./mg dry wt (54·2–85·0 d.p.m./mg dry wt) to 939·0 d.p.m./mg dry wt (635·9–1596·0 d.p.m./mg dry wt; P < 0·03), 145·0 d.p.m./mg dry wt (127·0–293·9 d.p.m./mg dry wt; P < 0·05) and 146·0 d.p.m./mg dry wt (77·5–187·0 d.p.m./mg dry wt; P < 0·03) respectively. These results suggest that ET-1 activates the phospholipase A2 and PtdIns(4,5)P2-specific phospholipase C in human proliferative endometrium, resulting in the generation of PGF2α and second messengers respectively which are pivotal to endometrial function.
Journal of Endocrinology (1992) 135, 383–390
