Effect of estrogen and progesterone treatment on calcium uptake by the myometrium and smooth muscle of the lower urinary tract

Current status and challenges in uterine myometrial tissue engineering

The uterus undergoes significant modifications throughout pregnancy to support embryo development and fetal growth. However, conditions like fibroids, adenomyosis, cysts, and C-section scarring can cause myometrial damage. The importance of the uterus and the challenges associated with myometrial damage, and the need for alternative approaches are discussed in this review. The review also explores the recent studies in tissue engineering, which involve principles of combining cells, scaffolds, and signaling molecules to create functional uterine tissues. It focuses on two key approaches in uterine tissue engineering: scaffold technique using decellularized, natural, and synthetic polymer and 3D bioprinting. These techniques create supportive structures for cell growth and tissue formation. Current treatment options for myometrial damage have limitations, leading to the exploration of regenerative medicine and integrative therapies. The review emphasizes the potential benefits of tissue engineering, including more effective and less invasive treatment options for myometrial damage. The challenges of developing biocompatible materials and optimizing cell growth and differentiation are discussed. In conclusion, uterine tissue engineering holds promise for myometrial regeneration and the treatment of related conditions. This review highlights the scientific advancements in the field and underscores the potential of tissue engineering as a viable approach. By addressing the limitations of current treatments, tissue engineering offers new possibilities for improving reproductive health and restoring uterine functionality. Future research shall focus on overcoming challenges and refining tissue engineering strategies to advance the field and provide effective solutions for myometrial damage and associated disorders.

Estrogen Signaling in ERα-Negative Breast Cancer: ERβ and GPER

Estrogen receptors are important regulators of the growth of breast tumors. Three different receptors for estrogens have been identified in breast tumors, two nuclear receptors, ERα and ERβ, and a G-protein coupled estrogen receptor 1 (GPER) that initiates non-genomic effects of estrogens in the cytosol. Recent findings show that the stimulation of cytoplasmic ERα and ERβ also triggers non-genomic signaling pathways. The treatment of breast cancer with anti-estrogens depends on the presence of ERα. About 40% of all breast cancers, however, do not express ERα. One subgroup of these tumors overexpress Her-2, another important group is designated as triple-negative breast cancer, as they neither express ERα, nor progesterone receptors, nor do they overexpress Her-2. This review addresses the signaling of ERβ and GPER in ERα-negative breast tumors. In addition to the well-established EGF-receptor transactivation pathways of GPER, more recent findings of GPER-dependent activation of FOXO3a, the Hippo-pathway, and HOTAIR-activation are summarized.

The neuroprotective steroid progesterone promotes mitochondrial uncoupling, reduces cytosolic calcium and augments stress resistance in yeast cells

The steroid hormone progesterone is not only a crucial sex hormone, but also serves as a neurosteroid, thus playing an important role in brain function. Epidemiological data suggest that progesterone improves the recovery of patients after traumatic brain injury. Brain injuries are often connected to elevated calcium spikes, reactive oxygen species (ROS) and programmed cell death affecting neurons. Here, we establish a yeast model to study progesterone-mediated cytoprotection. External supply of progesterone protected yeast cells from apoptosis-inducing stress stimuli and resulted in elevated mitochondrial oxygen uptake accompanied by a drop in ROS generation and ATP levels during chronological aging. In addition, cellular Ca2+ concentrations were reduced upon progesterone treatment, and this effect occurred independently of known Ca2+ transporters and mitochondrial respiration. All effects were also independent of Dap1, the yeast orthologue of the progesterone receptor. Altogether, our observations provide new insights into the cytoprotective effects of progesterone.

Estrogen induces phospholipase A2 activation through ERK1/2 to mobilize intracellular calcium in MCF-7 cells

The principal secreted estrogen, 17beta-estradiol rapidly activates signaling cascades that regulate important physiological processes including ion transport across membranes, cytosolic pH and cell proliferation. These effects have been extensively studied in the MCF-7 estrogen-responsive human breast carcinoma cell line. Here, we demonstrate that a physiological concentration of 17beta-estradiol caused a rapid, synchronous and transient increase in intracellular calcium concentration in a confluent monolayer of MCF-7 cells 2-3 min after treatment. This response was abolished when cells were pre-incubated with the phospholipase A(2) (PLA(2)) inhibitor quinacrine or with the cyclooxygenase inhibitor indomethacin. The translocation of GFP-cPLA(2)alpha to perinuclear membranes occurred 1-2 min after 17beta-estradiol treatment; this translocation was concurrent with the transient phosphorylation of cPLA(2)alpha at serine residue 505. The phosphorylation and translocation of cPLA(2) were sensitive to inhibition of the extracellular signal regulated kinase (ERK) signaling cascade and occurred simultaneously with a transient activation of ERK. The phosphorylation of cPLA(2) could be stimulated by membrane impermeable 17beta-estradiol conjugated to bovine serum albumen and was blocked by an antagonist of the classical estrogen receptor. Here we show, for the first time, that PLA(2) and the eicosanoid biosynthetic pathway are involved in the 17beta-estradiol induced rapid calcium responses of breast cancer cells.

Estrogen therapy induces collateral and microvascular remodeling

Estrogen increases proliferation and migration of cultured endothelial cells and perfusion of ischemic hindlimbs of rabbits. We tested the hypothesis that estrogen is angiogenic and arteriogenic in the heart during progressive coronary occlusion. Ovariectomized (OVX) and 17beta-estradiol (1 mg.kg(-1).wk(-1) im)-treated OVX (OVX-ES) female New Zealand White rabbits were instrumented with an ameroid occluder on a proximal coronary artery. Four weeks after implantation of an ameroid occluder, we measured myocardial perfusion with microspheres at rest and during adenosine-induced maximal vasodilation. The heart was fixed by perfusion at physiological pressure, and capillary angiogenesis and remodeling were assessed by image analysis of tissue sections in collateral-dependent myocardium. Coronary conductance was higher at rest and during maximal vasodilation in collateral-dependent myocardium of OVX-ES than OVX rabbits. Estrogen treatment increased the wall-to-lumen ratio of collateral vessels while it decreased the wall-to-lumen ratio of noncollateral arteries in normal regions. In normal and collateral-dependent myocardium, mean capillary diameter and capillary volume density were greater in OVX-ES rabbits. However, estrogen had no effect on capillary length density in either region of the myocardium. These data suggest that estrogen induces remodeling of the collateral vasculature and may stimulate growth of the resistance vessels, thereby providing protection during development of a gradual coronary occlusion.

Estrogenic endocrine disruptive components interfere with calcium handling and differentiation of human trophoblast cells

During development, calcium (Ca) is actively transported by placental trophoblasts to meet fetal nutritional and the skeletal mineralization needs. Maternal exposure to estrogenic pesticides, such as 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT) and methoxychlor (MTC), has been shown to result in reproductive disorders and/or abnormal fetal development. In this study, we have examined the effects of exposure of trophoblastic cells to MTC and DTT, in comparison to 17beta-estradiol (E2) and diethylstilbestrol (DES), to test the hypothesis that cellular Ca handling is a target for these endocrine disruptive components. Treatment with DDT, MTC, DES, or E2 increased cellular Ca uptake, and the expression of trophoblast-specific human Ca binding protein (HCaBP) was down-regulated by both MTC and DDT. Treatment with MTC, DDT, and DES inhibited cell proliferation, induced apoptosis, and suppressed expression of several trophoblast differentiation marker genes. These effects were reversed by overexpression of metallothionein IIa, a gene highly responsive to cadmium and other metals. These results strongly suggest that trophoblast Ca handling functions are endocrinally modulated, and that their alteration by candidate endocrine disruptors, such as MTC and DDT, constitutes a possible pathway of the harmful effects of these components on fetal development.

Effect of genistein on replication of bovine herpesvirus type 1

OBJECTIVE

To study the antiviral activity of genistein, a soya isoflavone, on in vitro replication of bovine herpesvirus type 1 (BHV-1).

SAMPLE POPULATION

Madin-Darby bovine kidney (MDBK) cells.

PROCEDURE

Effects of genistein on the magnitude and kinetics of inhibition of BHV-1 phosphorylation of glycoprotein E (gE) and in vitro replication of BHV-1 in MDBK cells were evaluated. Antiviral activity of genistein was compared with 2 compounds, estradiol-17beta (EST) and tamoxifen (TAM), that have estrogenic and antiestrogenic activity, respectively. High-performance liquid chromatography (HPLC) was used to determine the concentration of genistein in medium from infected and uninfected MDBK cultures.

RESULTS

Genistein reduced BHV-1, but not gE-deleted BHV-1 (BHV-1gEdelta3.1), replication by 90% at 18 hours after inoculation. This inhibition was not sustained through 24 hours after inoculation. The genistein concentration in media from MDBK cells was decreased by 40% during BHV-1 infection, compared with 16% for uninfected cells, at 24 hours after inoculation. Genistein inhibited gE phosphorylation and BHV-1 replication in a dose-dependent manner. Dosing with 25 microM genistein at 0 and 12 hours after inoculation of BHV-1 was optimal for decreasing BHV-1 replication. Estradiol-17beta EST and TAM did not affect BHV-1 replication.

CONCLUSIONS AND CLINICAL RELEVANCE

The decrease in genistein concentration was a viral infection-dependent event. Genistein is an inhibitor of BHV-1 replication because of its ability to inhibit tyrosine kinase activity. A possible application may be for the control of BHV-1 infection in cattle by feeding soya products rich in genistein prior to or during periods of stress.

Diversity in the mechanisms of gene regulation by estrogen receptors

The sequencing of the human genome has opened the way for using bioinformatics to identify sets of genes controlled by specific regulatory signals. Here, we review the unexpected diversity of DNA response elements mediating transcriptional regulation by estrogen receptors (ERs), which control the broad physiological effects of estrogens. Consensus palindromic estrogen response elements are found in only a few known estrogen target genes, whereas most responsive genes contain only low-affinity half palindromes, which may also control regulation by other nuclear receptors. ERs can also regulate gene expression in the absence of direct interaction with DNA, via protein-protein interactions with other transcription factors or by modulating the activity of upstream signaling components, thereby significantly expanding the repertoire of estrogen-responsive genes. These diverse mechanisms of action must be taken into account in screening for potential estrogen-responsive sequences in the genome or in regulatory regions of target genes identified by expression profiling.

The role of mitogen-activated protein (MAP) kinase in breast cancer

Mitogen-activated protein kinase (MAP kinase) cascades transmit and amplify signals involved in cell proliferation as well as cell death. These signal transduction pathways serve as an indicators of the intensity of trafficking induced by various growth factor, steroid hormone, and G protein receptor mediated ligands. Three major MAP kinase pathways exist in human tissues, but the one involving ERK-1 and -2 is most relevant to breast cancer. Peptide growth factors acting through tyrosine kinase containing receptors are the major regulators of ERK-1 and -2. Estradiol, progesterone, and testosterone can act non-genomically via membrane associated receptors to activate MAP kinase as can various other ligands acting through heterotrimeric G protein receptors. Recent studies demonstrate that breast cancers frequently contain an increased proportion of cells with the activated form of MAP kinase. In estrogen receptor positive breast tumors, MAP kinase pathways can exert "cross talk" effects at the level of ER induced transcription as well as at the level of the cell cycle. Estradiol stimulates cell proliferation by mechanisms which involve activation of MAP kinase, either through rapid, non-transcription effects or by increasing growth factor production and consequently MAP kinase. Progesterone and androgens also stimulate MAP kinase through both of these two mechanisms. Strategies used to treat hormone dependent breast cancer appear to result in upregulation of MAP kinase activation. Direct experimental data demonstrate that the pressure of estradiol deprivation results in the upregulation of MAP kinase in breast cancer cells growing in tissue culture and as xenografts. A number of investigators have now studied the expression of activated MAP kinase in human breast cancer tissues by enzymatic assay and by immunohistochemical techniques. Approximately half of breast tumors express more activated MAP kinase than does the surrounding benign tissue. Studies show a trend toward higher MAP kinase activity in primary tumors of node positive than in node negative patients. However, larger numbers of patients must be studied for these results to achieve statistical significance. The up-regulation of MAP kinase activity does not represent mutations of Ras, but appears to result from enhancement of growth factor pathway activation. No data are yet available on the relationship between MAP kinase activation and apoptosis. Additional studies are now needed to determine the precise relationship between MAP kinase activation and tumor proliferation, apoptosis, and degree of invasiveness as well as on disease free and overall survival.

Differential expression of estrogen receptors alpha and beta in adult rat accessory sex glands and lower urinary tract

Estrogens induce pronounced structural and functional changes in male accessory sex glands and the lower urinary tract in both sexes, but the exact mechanisms of estrogen action are not fully understood. This study was undertaken to localise the tissue cell types that express estrogen receptor in adult rats, and to determine the receptor subtype (ER alpha and ER beta) in order to identify sites that may respond directly to estrogens. In the male accessory sex glands (seminal vesicles, prostatic lobes and ampullary glands), ER beta mRNA and protein were strongly expressed in the epithelium but not in the stroma, while ER alpha mRNA was present only in the fibromuscular tissue surrounding the prostatic collecting ducts in the posterior periurethral region and in ampullary gland stroma. In the epithelium of the urinary bladder and urethra of both sexes, high level of ER beta mRNA and protein, but no ER alpha mRNA, was detected. The connective tissue in urinary bladder of both males and females, as well as that in prostatic urethra in males expressed ER alpha mRNA. The neural cells in the autonomic ganglia of the prostatic plexus were strongly positive for ER beta mRNA, but were completely devoid of ER alpha. We conclude that ER beta is the predominant ER subtype in the epithelium of adult male rat accessory sex glands and the lower urinary tract of both males and females, as well as in the prostatic neural plexus regulating the function of the lower urinary tract in males, while ER alpha is present only in the stromal compartment of distinct sites. These results indicate that in these tissues in intact adults there are multiple targets for direct estrogen action. Furthermore, the differential or complementary expression of the two ER subtypes suggests that they may have specific functions, and may explain the complex structural and functional changes induced by estrogens.

Mechanisms controlling the function and life span of the corpus luteum

The primary function of the corpus luteum is secretion of the hormone progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follicular granulosal and thecal cells after ovulation. Luteinizing hormone (LH) from the anterior pituitary is important for normal development and function of the corpus luteum in most mammals, although growth hormone, prolactin, and estradiol also play a role in several species. The mature corpus luteum is composed of at least two steroidogenic cell types based on morphological and biochemical criteria and on the follicular source of origin. Small luteal cells appear to be of thecal cell origin and respond to LH with increased secretion of progesterone. LH directly stimulates the secretion of progesterone from small luteal cells via activation of the protein kinase A second messenger pathway. Large luteal cells are of granulosal cell origin and contain receptors for PGF(2alpha) and appear to mediate the luteolytic actions of this hormone. If pregnancy does not occur, the corpus luteum must regress to allow follicular growth and ovulation and the reproductive cycle begins again. Luteal regression is initiated by PGF(2alpha) of uterine origin in most subprimate species. The role played by PGF(2alpha) in primates remains controversial. In primates, if PGF(2alpha) plays a role in luteolysis, it appears to be of ovarian origin. The antisteroidogenic effects of PGF(2alpha) appear to be mediated by the protein kinase C second messenger pathway, whereas loss of luteal cells appears to follow an influx of calcium, activation of endonucleases, and an apoptotic form of cell death. If the female becomes pregnant, continued secretion of progesterone from the corpus luteum is required to provide an appropriate uterine environment for maintenance of pregnancy. The mechanisms whereby the pregnant uterus signals the corpus luteum that a conceptus is present varies from secretion of a chorionic gonadotropin (primates and equids), to secretion of an antiluteolytic factor (domestic ruminants), and to a neuroendocrine reflex arc that modifies the secretory patterns of hormones from the anterior pituitary (most rodents).

Estrogen-induced activation of mitogen-activated protein kinase requires mobilization of intracellular calcium

Estrogens and growth factors such as epidermal growth factor (EGF) act as mitogens promoting cellular proliferation in the breast and in the reproductive tract. Although it was considered originally that these agents manifested their mitogenic actions through separate pathways, there is a growing body of evidence suggesting that the EGF and estrogen-mediated signaling pathways are intertwined. Indeed, it has been demonstrated recently that 17beta-estradiol (E2) can induce a rapid activation of mitogen-activated protein kinase (MAPK) in mammalian cells, an event that is independent of both transcription and protein synthesis. In this study, we have used a pharmacological approach to dissect this novel pathway in MCF-7 breast cancer cells and have determined that in the presence of endogenous estrogen receptor, activation of MAPK by E2 is preceded by a rapid increase in cytosolic calcium. The involvement of intracellular calcium in this process was supported by the finding that the presence of EGTA and Ca2+-free medium did not affect the activation of MAPK by E2 and, additionally, that this response was blocked by the addition of the intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate. Cumulatively, these data indicate that the estrogen receptor, in addition to functioning as a transcription factor, is also involved, through a nongenomic mechanism, in the regulation of both intracellular calcium homeostasis and MAPK-signaling pathways. Although nongenomic actions of estrogens have been suggested by numerous studies in the past, the ability to link estradiol and the estrogen receptor to a well defined signaling pathway strongly supports a physiological role for this activity.

Downregulation by estrogen of nitric oxide synthase activity in the female rabbit lower urinary tract

OBJECTIVES

Because female urinary tract tissues are considered to be targets for estrogen, and because nitric oxide (NO) is known to participate in the nerve-induced relaxation in the lower urinary tract, the effect of estrogen on nitric oxide synthase (NOS) in the upper and lower urinary tracts was examined.

METHODS

Ovariectomized rabbits were treated with polyestradiol phosphate, and NOS in both cytosolic and particulate fractions from kidney, urinary pelvis, ureter, urinary bladder, trigonum, and urethra was characterized. NOS activity was measured by the formation of [14C]-L-citrulline from [14C]-L-arginine.

RESULTS

NOS was considerably higher in cytosolic than in particulate fractions from all urinary tracts, and activity in both fractions was highly calcium dependent. NOS activity was much lower (fourfold to eightfold) in the kidney and pelvis than in the ureter. Estrogen treatment caused no change in NOS in either fraction from upper urinary tract tissues. In the lower urinary tract, NOS was slightly higher in the bladder and trigonum than in the urethra, and activities were comparable to NOS in the ureter. In contrast to the upper urinary tract, estrogen treatment led to a significant reduction of cytosolic NOS in the bladder, trigonum, and urethra. Estrogen, however, caused no significant change in the particulate NOS.

CONCLUSIONS

Downregulation by estrogen in cytosolic NOS in the tissue of the lower urinary tract is consistent with the presence of estrogen receptors and suggests a physiologic significance.

Estrogens cause rapid activation of IP3-PKC-alpha signal transduction pathway in HEPG2 cells

The mechanisms through which steroids affect target cells are not fully understood. In addition to the classic model, there is now increasing evidence that steroids can exert rapid actions. It must still be elucidated if rapid and slow estrogen actions produce co-operative and/or integrative functions. The effects of estrogen on inositol trisphosphate (IP3) production and PKC-alpha levels on membrane in the HEPG2 cell line have been investigated. Results show that estrogen addition to HEPG2 cells causes a rapid increase of IP3 production. The effect was totally inhibited by pre-incubation with tyrosine-kinase inhibitor genisteine and with the anti-estrogen ICI 182,780. An increased PKC-alpha level on the membrane fraction was present 30 min after estrogen exposure. The strong signal could elicit a variety of cellular responses such as modulation of ion channel, stimulation of cell proliferation, and phosphorylation of cytosolic ER. The ability of estrogen to trigger IP3 production in human hepatoma cells is a novel aspect of estrogen action that requires the current model of hormone stimulation target cells to be revised.

Depolarization-dependent effect of flavonoids in rat uterine smooth muscle contraction elicited by CaCl2

1. The effects of the flavonoids genistein (3-60 microM), kaempferol (3-60 microM) and quercetin (1-100 microM) on KCl (60 mM)-induced tonic contraction in rat uterus and their modifications with the inhibitor of cAMP-dependent protein kinases (TPCK, 3 microM), the inhibitor of ornithine decarboxylase [alpha-difluoromethyl ornithine (DFMO), 10 mM] and the polyamine spermine (1 mM) have been assayed. The effects of the three flavonoids were also studied on the contraction elicited by CaCl2 (30 microM to 10 mM) on rat uterus incubated in medium lacking calcium and supplemented with 33, 60 or 90 mM of KCl. For comparison, the effects of the calcium channel blockers nifedipine and verapamil and the activator of adenylyl cyclase forskolin were assayed on contractions induced by KCl and CaCl2. 2. Genistein (IC50: 20.2 +/- 1.0 microM, n = 11), kaempferol (IC50: 10.1 +/- 0.8 microM, n = 8) and quercetin (IC50: 13.2 +/- 0.5 microM, n = 8) relaxed the tonic contraction induced by KCl (60 mM) in a concentration-dependent way. Verapamil (IC50: 70.1 +/- 5.8 nM, n = 7), nifedipine (IC50: 8.4 +/- 0.7 nM, n = 6) and forskolin (IC50: 0.62 +/- 0.08 microM, n = 14) also relaxed the KCl-induced contraction. TPCK (3 microM) significantly antagonized the effect of quercetin, kaempferol and forskolin (P < 0.01) but did not modify the effect of genistein. 3. Spermine (1 mM) increased the effects of genistein and verapamil and antagonized the effect of quercetin but did not modify those of kaempferol and forskolin. DFMO (10 mM) did not modify the effect of quercetin but increased that of genistein and antagonized those of kaempferol and forskolin. The addition of spermine (1 mM) plus DFMO (10 mM) antagonized the effect of quercetin. Spermine counteracted the effect of DFMO on forskolin but not on genistein. 4. KCl (33, 60 or 90 mM) did not produce contraction in calcium-free solution, but CaCl2 (30 microM to 10 mM) induced concentration-dependent contraction after depolarizing with KCl. The EC50 values for CaCl2 were: 0.74 +/- 0.08 (n = 12), 0.34 +/- 0.03 (n = 14) and 0.48 +/- 0.02 (n = 12) mM in a medium with 33, 60 or 90 mM of KCl, respectively. 5. Genistein (20 microM), kaempferol (10 microM), quercetin (15 microM), verapamil (70 nM), nifedipine (10 nM) and forskolin (0.5 microM) inhibited the concentration-response curve to CaCl2 in medium supplemented with 33, 60 or 90 mM of KCl. The effect of kaempferol was independent of the concentration of KCl in the incubation medium. However, the inhibitory effect of genistein on CaCl2-induced contraction was inversely related to the concentration of KCl in the medium. On the contrary, the effect of quercetin was directly related to the concentration of KCl in the medium. 6. The antagonism of verapamil, nifedipine and forskolin on CaCl2-induced contraction seems to be related to the degree of depolarization because increasing the KCl in the medium counteracted their effects. 7. Our results suggest that (1) cAMP contributes to the relaxant effects of quercetin and kaempferol on KCl (60 mM)-induced tonic contraction; (2) polyamines are involved in the relaxant effects of forskolin and kaempferol on KCl-induced tonic contraction but not on CaCl2-induced contraction in the depolarized uterus, and (3) the flavonoids assayed also possess a calcium antagonist action but show a different behavior toward the calcium channel blockers and the cAMP enhancer forskolin.

Potent inhibition by tamoxifen of spontaneous and agonist-induced contractions of the human myometrium and intramyometrial arteries

OBJECTIVE

Our purpose was to elucidate the mechanism of direct (nongenomic) action of antiestrogens on spontaneous and agonist-induced contractions of the human myometrium and uterine arteries.

STUDY DESIGN

Myometrial strips and pieces of uterine arteries were obtained from nonpregnant premenopausal women undergoing hysterectomy. Spontaneous activity of myometrium and responses of myometrium and artery to K(+)-depolarization and vasopressin were recorded under isometric conditions. Quantification of the responses was done by planimetry.

RESULTS

The 50% inhibitory concentration values for tamoxifen, clomiphene, and cyclofenil in the case of myometrial spontaneous activity were 2.8, 43, and 331 nmol/L, respectively. Vasopressin-induced contractions in both the myometrium and arteries were potently inhibited by tamoxifen, and the 50% inhibitory concentration for the myometrium (1.4 nmol/L) was significantly lower (p < 0.05) than that for the arteries (11 nmol/L). Although tamoxifen caused no inhibition of responses induced by high potassium chloride (80 mmol/L), responses induced by low potassium chloride (20 mmol/L) were inhibited by 40% to 50% in both the myometrium and arteries. Glibenclamide reversed the inhibition by tamoxifen of spontaneous myometrial activity.

CONCLUSIONS

Tamoxifen is a highly potent inhibitor of the contractile activity of the human nonpregnant myometrium and uterine arteries. It is suggested that tamoxifen could have strong potential in the treatment of dysmenorrhea.

17beta-estradiol in vitro affects Na-dependent and depolarization-induced Ca2+ transport in rat brain synaptosomes

Effects of 17beta-estradiol (E2) in vitro on Na-dependent Ca2+ efflux from, and depolarization-induced Ca2+ uptake into, the nerve cell were studied with the use of synaptosomes isolated from the brain stem, mesencephalic reticular formation (MRF), caudate nucleus and the hippocampus of long-term ovariectomized adult female rats. It was found that E2 (1) at a concentration of 10 nM or lower, stimulates Na-dependent Ca2+ efflux in the caudate nucleus and hippocampus, and does not affect the efflux in MRF and brain stem; (2) at concentrations above 10 nM has no effect on the Ca2+ efflux in any of the four structures investigated; and (3) produces a biphasic effect on the depolarization-induced Ca2+ uptake, increasing it in all structures except MRF at 10 nM concentration, and decreasing it at concentrations higher than 10 nM, irrespective of the structure investigated. These results suggest that E2, acting at extranuclear sites, modulates synaptic transmission via alterations of Ca2+ transport mechanisms in nerve endings.

Non-genomic effects of estrogen and the vessel wall

Estrogen, like other steroids, is now believed to possess rapid membrane effects independent of the classical gene activation pathway of steroid action. The presence of membrane estrogen receptors has been demonstrated in different cell types, but not yet in vascular tissue. In vivo, estrogen administration rapidly promotes acetylcholine-induced vasodilation of the coronary and peripheral vascular beds of postmenopausal women. Estrogen also causes relaxation of precontracted isolated arterial segments and perfused organ preparations, within minutes of administration of the hormone. These rapid vasomotor effects of estrogen may be related to blockade of the cell membrane voltage-dependent calcium channels, resulting in inhibition of extracellular Ca2+ mobilization and flux. Recently, estradiol has been shown to rapidly affect cyclic nucleotide turnover in vascular segments, smooth muscle, and epithelial cell cultures, suggesting the possibility of a "cross-talk" between membrane-mediated events and nuclear receptor activation.

Non-genomic effects of catecholestrogens in the in vitro rat uterine contraction

1. The effects of catecholestrogens 2-hydroxyestradiol (2-OH E2, 0.6-30 microM), 4-hydroxyestradiol (4-OH E2, 1-30 microM) and 2-methoxyestradiol (2-MeO E2, 0.6-30 microM) on rat uterine contraction induced by KCl (60 mM), have been assayed. 2. All drugs assayed relaxed the tonic-contraction induced by KCl in a concentration-dependent way. The EC50s were: 4.4 +/- 0.5, 4.2 +/- 0.3 and 8.5 +/- 0.7 microM for 2-MeO E2, 2-OH E2 and 4-OH E2, respectively. This relaxing effect was counteracted by CaCl2 (1-10 mM) but not by the calcium channel agonist Bay k 8644 (1 nM-1 microM). 3. The effect of 2-MeO E2 is not modified by propranolol (1 microM), cycloheximide (35 microM), actinomycin D (4 microM), alpha-difluoromethyl-ornithine (10 mM) or genistein (10 microM). Nor did cycloheximide (35 microM) or actinomycin D (4 microM) modify the relaxing effect of 2-OH E2 and 4-OH E2. Propranolol (1 microM) significantly increased the effect of 4-OH E2 but not the effect of 2-OH E2. 4. Our results suggest that the relaxing effect of catecholestrogens in the rat uterus is a non-genomic effect and could be related to inhibition of extracellular calcium entry.

Modulation of urinary bladder function by sex hormones in streptozotocin-diabetic rats

The modulation of urinary bladder function by sex hormones was examined in castrated and sham-operated male and female streptozotocin-diabetic rats. Male and female diabetic rats weighed less than age-matched controls and had significantly greater serum glucose levels and bladder weights. Castration had no effect on bladder mass and did not alter the diabetes-induced changes in rat or bladder mass. Protein concentrations were significantly increased and collagen concentrations were significantly decreased in bladders from diabetic rats compared with non-diabetics. Sex or castration had no effects on protein or collagen concentration of bladders from nondiabetic and diabetic rats. There were no differences in water consumption and urine excretion between male and female nondiabetic rats, and no effects of castration were observed on micturition in nondiabetic rats. Ovariectomy followed by diabetes caused a significant increase in urine excretion compared with diabetes alone. Ovariectomized diabetic rats had increased mean and maximal micturition volumes when compared with other female rats. Orchiectomy had no effects on the expected increases in micturition associated with diabetes. Diabetes in male rats caused significant increases in contractile responses of bladder strips to field stimulation, carbachol, KCl and high concentrations of ATP. In both nondiabetic and diabetic groups, orchiectomy had no effects on the contractile responses compared with sham operation. Similarly, in bladder strips from diabetic females, contractile responses to carbachol, KCl and high concentrations of ATP were significantly increased compared with those of nondiabetics, and were unchanged by ovariectomy. However, ovariectomy in nondiabetic rats caused significant decreases in contractile responsiveness to nerve stimulation, effects which were only partially prevented by diabetes. The data suggest that there are few differences between male and female rats in their sensitivity to streptozotocin and the effects of diabetes on micturition, bladder collagen and protein concentration, and the responsiveness of bladder strips to contractile agents. The changes in bladder function observed after induction of diabetes do not appear to be related to changes in sex hormone levels. The major differences noted between males and females were the decreased responsiveness of bladders from nondiabetic ovariectomized female rats to field stimulation. In conjunction with previous data obtained in this laboratory, the study suggests that the responses to field stimulation are more sensitive to the effects of ovariectomy than are the responses to contractile agonists.

Effect of ovarian steroids and diethylstilbestrol on the contractile responses of the human myometrium and intramyometrial arteries

Estriol, estradiol, progesterone and diethylstilbestrol in the concentration range of 0.2-40 microM inhibited the spontaneous contractions of the myometrium in a dose-dependent manner but the differences in IC50 values obtained with different hormones were not statistically significant. All these hormones caused a concentration-dependent inhibition of the K(+)-induced contraction. The IC50 values were lowest for diethylstilbestrol and highest for estriol. Vasopressin at concentrations of 1.5 x 10(-6) - 1.8 x 10(-3) U/ml stimulated myometrial contractions. These responses were also inhibited by ovarian steroids and diethylstilbestrol. The IC50 values for estriol and progesterone were significantly higher than for estradiol or diethylstilbestrol. The values for estriol and progesterone did not differ significantly. In the uterine arteries, which lacked spontaneous activity, ovarian steroids and diethylstilbestrol inhibited contractions induced by K+ depolarization. As with myometrium, the lowest effect was observed with estriol and the highest with diethylstilbestrol. A dose-dependent inhibition by all four hormones (0.2-40 microM) of vasopressin-induced contractile responses of the uterine arteries was observed. With the lowest concentration of progesterone, however, the arterial response to vasopressin was enhanced. The increases by progesterone (0.02 and 0.2 microM) of responses induced by vasopressin were statistically significant (P < 0.05). The present data strongly suggest that, in human myometrium and uterine arteries, ovarian steroids and diethylstilbestrol cause a more pronounced inhibition of receptor-mediated than of voltage-dependent Ca2+ channels. The increase by a very low (physiological) concentration of progesterone of vasopressin-induced responses in both myometrium and arteries may be of significance in the pathophysiology of dysmenorrhea.

Uterine contraction and physiological mechanisms of modulation

Control of the smooth muscle in the uterus (the myometrium), is of vital importance during pregnancy and parturition. It is therefore understandable that several physiological mechanisms (neuronal, hormonal, metabolic, and mechanical) play a role in the control of myometrial activity. As our knowledge of the mechanism of uterine contraction has increased much in recent years, it is now possible to begin to explain, in some detail, how the contractile activity may be modulated. A detailed account of the mechanism of contraction in the uterus is therefore given, followed by examples of modulation of this process for each of the four physiological methods listed above. Examples have been chosen to illustrate either general or particular mechanisms of modulation. The goal of many working in this field is to understand these processes and thus prevent preterm labor and uterine dysfunction in term labor, which are still significant clinical problems.

The influence of ovariectomy and estradiol replacement on urinary bladder function in rats

Female Fischer 344 rats were ovariectomized or sham operated and treated with oil or estradiol cypionate (100 mg./100 gm./month) for two or four months. Rats were then placed in metabolism cages for measurement of micturition characteristics, and bladders were removed for bladder strip studies. Ovariectomy had no effects on micturition characteristics. However, estradiol treatment of ovariectomized rats caused significant increases in water consumption and urine excretion, and in mean and maximal micturition volumes compared to both ovariectomized and sham-operated rats. These effects were more pronounced at four months. Estradiol treatment also caused significant increases in bladder body mass, while ovariectomy was without effect. Two months after ovariectomy and/or estradiol treatment, there were no differences in contractile responses of bladder body or base strips to contractile agents when compared to shams. However, after four months, ovariectomy caused significant decreases in contractile responsiveness to nerve stimulation. ATP, carbachol, and KCl compared to sham-operated rats. Estradiol treatment caused increased responsiveness to nerve stimulation, ATP, carbachol, and KCl compared to ovariectomized rats, and to carbachol compared to sham operated rats. Possible causes for the effects of ovariectomy on bladder contractility include decreases in calcium influx. Although estradiol reversed the effects of ovariectomy on bladder function, in addition we observed some indirect effects which were probably the result of estradiol-induced polyuria and increases in bladder mass.

Keratinization of rat vaginal epithelium--V. Modulation of intracellular calcium by estradiol

Changes in the calcium levels under the influence of estradiol were investigated in rat vaginal epithelial cells (VEC). After single estradiol injection, the immature rats showed 1.5-fold increase in Ca2+ levels within 15 min when compared to control animals. Progesterone priming brought calcium levels well below control values throughout the experimental period (up to 12 h). Ca2+ levels in serum did not show any appreciable change. Localization of calcium in VEC with electron microscopy showed aggregates of calcium oxalate on the inner nuclear membrane, nucleolus, mitochondria and keratohyaline granules. After 15 min of estradiol priming, maximum electron density was seen on all these cell organelles mentioned above, however, by 30 min the electron density was reduced considerably and did not increase during the experimental period (up to 12 h).

Oestrogen-induced changes in muscarinic receptor density and contractile responses in the female rabbit urinary bladder

Mature ovariectomized rabbits were treated for 1, 4 or 8 weeks with oestrogen, and the effects on contractile responses and on muscarinic receptor density in the isolated urinary bladder were studied. Oestrogen treatment caused a significant increase in the weight of the bladders. The responses to K+ (124 mM) were depressed, but not the maximum responses to carbachol. The frequency-response curve to electrical stimulation was shifted to the right after 4 and 8 weeks of treatment, but the maximum response was not reduced. There was also a (non-significant) shift to the right of the carbachol concentration-response curve. Pre-treatment with scopolamine revealed a significant reduction of the non-cholinergic response to electrical stimulation after oestrogen treatment compared to controls. Binding of [3H]quinuclidinyl benzilate (QNB) was saturable and of high affinity. There were no changes in apparent dissociation constant after oestrogen treatment. However, the muscarinic receptor density decreased already after 1 week of treatment and was only 10% of the control after 4 weeks. It is concluded that oestrogen treatment causes a down-regulation of muscarinic receptors in the rabbit urinary bladder, but the consequences for contractile activation through muscarinic receptors seem to be small.

Sonographic study of the endometrial responses to ovarian hormones in patients receiving ovarian stimulation

A total of 486 endometrial sonograms from 60 cases were reviewed to study the endometrial responses. There was a significant change in the proportion of each sonographic criterion between the pre- and post-ovulatory phases. After ovulation endometrial image showed distinct changes, and its thickness increased. These results suggest that classification of endometrial sonograms according to criteria and thickness measurements provides useful information.

Ca2+ uptake by rat brain region synaptosomes following in vivo administration of ovarian steroids

Effects of progesterone (P) and estradiol-17 beta benzoate (EB), applied s.c. into sexually mature, long-term ovariectomized (OVX) rats, on subsequent depolarization-induced uptake of Ca2+ were studied in synaptosomes isolated from the brain stem, mesencephalic reticular formation (MRF), nucleus caudatus putamen (NCP) and the hippocampus. In intact animals, synaptosomal Ca2+ uptake differed from region to region: it was lowest in the brain stem and highest in the hippocampus. In comparison to intact animals, ovariectomy resulted in a marked increase of the uptake regardless the structure investigated, suggesting an inhibitory action of ovaries on the uptake of Ca2+ in a considerable portion of rat brain. Single injection of 2 mg P, given to OVX rats 24 h prior to decapitation, evoked a marked decrease in Ca2+ uptake by synaptosomes of the brain stem and MRF and particularly by those of NCP and the hippocampus. Single injection of 5 micrograms EB into OVX animals 72 h prior to the experiment was as effective as P in inhibiting Ca2+ uptake by synaptosomes of the brain stem and MRF, but less effective than P in case of NCP and the hippocampus. This suggests involvement of P and EB in the modulation of synaptic transmission by affecting neuronal Ca2+ uptake.

Contractile properties of chemically skinned fibers from pregnant rat myometrium: existence of an internal Ca-store

Smooth muscle fibers isolated from pregnant rat myometrium were skinned by saponin treatment. Properties of the contractile system and the involvement of an intracellular source of activator calcium were studied. (1) In the presence of 4 mM total EGTA, skinned fibers contracted in a concentration-dependent manner to micromolar applications of calcium ions. Rat myometrium exhibited a high calcium sensitivity (80% of the maximum contraction was achieved in the presence of 10(-6) M Ca2+). (2) Several divalent cations induced concentration-dependent contractile responses in skinned uterine muscle. The rank order of potency was: Ca2+ greater than Mn2+ greater than Sr2+ greater than Ba2+. All these divalent cation-activated contractions were antagonized by trifluoperazine in a concentration-dependent manner. (3) Pretreatment of skinned fibers with cAMP (5 X 10(-5)-5 X 10(-4) M) depressed cation-activated contractions. This effect was dependent on the free cation concentration. (4) In the presence of a low EGTA concentration (0.1 mM) the pCa-tension curve was shifted to the right with a 2.5-fold increase in the Ca-concentration required to induce half-maximum contraction. (5) After Ca-loading (10(-6) M Ca2+ for 3 min in low EGTA-containing solution), total replacement of K+ ions by choline induced a small and tonic contraction. In these conditions, the ionophore A23287 (5 X 10(-8) M-5 X 10(-5) M) and inositol 1,4,5-triphosphate (InsP3; 2 X 10(-6) M-2 X 10(-5) M) also produced contractions of skinned uterine fibers even in the presence of NaN3 (5 mM) and of NaCN (5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Increase by oestrogen of calcium entry and calcium channel density in uterine smooth muscle

1 The effect of in vivo oestrogen treatment on both 45Ca influx in myometrial strips and the kinetics of [3H)-nitrendipine binding in the isolated plasma membrane (PM) was studied. 2 After four days of continuous oestrogen treatment of ovariectomized rats, 45Ca influx in both resting (unstimulated) and K-stimulated myometrium was substantially increased. 3 Oestrogen treatment significantly increased the density in PM of nitrendipine binding sites and also caused a slight and insignificant increase in the affinity for nitrendipine. 4 The data suggest that the increase in Ca entry following oestrogen treatment probably results from an increase in calcium channel density.