SEX STEROID HORMONE RECEPTORS IN THE DEVELOPING FEMALE REPRODUCTIVE TRACT OF LABORATORY RODENTS

Beneficiary and Adverse Effects of Phytoestrogens: A Potential Constituent of Plant-based Diet

BACKGROUND

Phytoestrogens are non-endocrine, non-steroidal secondary derivatives of plants and consumed through a plant-based diet also named as "dietary estrogens". The major sources of phytoestrogens are soy and soy-based foods, flaxseed, chickpeas, green beans, dairy products, etc. The dietary inclusion of phytoestrogen based foods plays a crucial role in the maintenance of metabolic syndrome cluster, including obesity, diabetes, blood pressure, cancer, inflammation, cardiovascular diseases, postmenopausal ailments and their complications. In recent days, phytoestrogens are the preferred molecules for hormone replacement therapy. On the other hand, they act as endocrine disruptors via estrogen receptor-mediated pathways. These effects are not restricted to adult males or females and identified even in development.

OBJECTIVE

Since phytoestrogenic occurrence is high at daily meals for most people worldwide, they focused to study for its beneficiary effects towards developing pharmaceutical drugs for treating various metabolic disorders by observing endocrine disruption.

CONCLUSION

The present review emphasizes the pros and cons of phytoestrogens on human health, which may help to direct the pharmaceutical industry to produce various phytoestrongen based drugs against various metabolic disorders.

Regenerative Medicine Approaches in Bioengineering Female Reproductive Tissues

Diseases, disorders, and dysfunctions of the female reproductive tract tissues can result in either infertility and/or hormonal imbalance. Current treatment options are limited and often do not result in tissue function restoration, requiring alternative therapeutic approaches. Regenerative medicine offers potential new therapies through the bioengineering of female reproductive tissues. This review focuses on some of the current technologies that could address the restoration of functional female reproductive tissues, including the use of stem cells, biomaterial scaffolds, bio-printing, and bio-fabrication of tissues or organoids. The use of these approaches could also be used to address issues in infertility. Strategies such as cell-based hormone replacement therapy could provide a more natural means of restoring normal ovarian physiology. Engineering of reproductive tissues and organs could serve as a powerful tool for correcting developmental anomalies. Organ-on-a-chip technologies could be used to perform drug screening for personalized medicine approaches and scientific investigations of the complex physiological interactions between the female reproductive tissues and other organ systems. While some of these technologies have already been developed, others have not been translated for clinical application. The continuous evolution of biomaterials and techniques, advances in bioprinting, along with emerging ideas for new approaches, shows a promising future for treating female reproductive tract-related disorders and dysfunctions.

New frontiers of developmental endocrinology opened by researchers connecting irreversible effects of sex hormones on developing organs

In the early 1960's, at Professor Bern's laboratory, University of California, Berkeley) in the US, Takasugi discovered ovary-independent, persistent vaginal changes in mice exposed neonatally to estrogen, which resulted in vaginal cancer later in life. Reproductive abnormalities in rodents were reported as a result of perinatal exposure to various estrogenic chemicals. Ten years later, vaginal cancers were reported in young women exposed in utero to the synthetic estrogen diethylstilbestrol (DES) and this has been called the "DES syndrome". The developing organism is particularly sensitive to developmental exposure to estrogens inducing long-term changes in various organs including the reproductive organs. The molecular mechanism underlying the persistent vaginal changes induced by perinatal estrogen exposure was partly demonstrated. Persistent phosphorylation and sustained expression of EGF-like growth factors, lead to estrogen receptor α (ESR1) activation, and then persistent vaginal epithelial cell proliferation. Agents which are weakly estrogenic by postnatal criteria may have major developmental effects, especially during a critical perinatal period. The present review outlines various studies conducted by four generations of investigators all under the influence of Prof. Bern. The studies include reports of persistent changes induced by neonatal androgen exposure, analyses of estrogen responsive genes, factors determining epithelial differentiation in the Müllerian duct, ESR and growth factor signaling, and polyovular follicles in mammals. This review is then expanded to the studies on the effects of environmental estrogens on wildlife and endocrine disruption in Daphnids.

Di-(2-ethylhexyl) Phthalate (DEHP) and Uterine Histological Characteristics

Phthalates have a long industrial history. It is suspected that phthalates and their metabolites have detrimental effects on reproduction and development. They are well-known for their anti-androgenic effects. Several studies have indicated that phthalates and their metabolites are reprotoxic in males and endocrine disruptors. Reproduction and embryogenesis occur in the uterus of female eutherian mammals. A horizontal analytical method is preferred to elucidate the toxic effects of phthalates on human reproduction. Nevertheless, there are vast numbers of known phthalates and not all of their modes of action have been clarified. Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer and has been the subject of numerous toxicological studies. However, few of these have reported on the toxic effects of DEHP, its metabolites, other phthalates, or mixtures on female reproduction. Acute and high doses of DEHP adversely affect uterine histology. Recently, it was disclosed that chronic exposures to low doses of DEHP have endocrine disruption efficacy. DEHP induces various cellular responses including modulation of the expression and regulation of steroid hormone receptors and transcription and paracrine factors. Uteri do not respond uniformly to DEHP exposure. The phenotypic manifestations and effects on fertility in response to DEHP and its metabolites may vary with species, developmental stage, and generation. Hence, DEHP exposure may histological alter the uterus and induce endometriosis, endometriosis, hyperplasia, myoma, and developmental and reproductive toxicity.

Surgical management of congenital uterine anomalies (including indications and surgical techniques)

The prevalence of congenital uterine anomalies (CUA) is reported to be 4.3-6.7% in the general population, 3.4%-8% in the infertile population, and 12.6-18.2% of those with recurrent miscarriages. They are the result of abnormal formation, differentiation, and fusion of the Müllerian or paramesonephric ducts during fetal life. To date, various classification systems have been proposed for the categorization of CUA, but the recently introduced ESHRE/ESGE classification seems to be a new, clear, and systematic categorization, which could be the basis for clinicians to rely on when they refer to CUA and their clinical impact either generally or concerning pregnancy outcomes. CUA are apparently related to an impaired reproductive outcome, while their exact clinical impact as well as the effectiveness of their treatment remain considered controversial. Surgery is indicated in women presenting with symptoms related to specific uterine anomalies, especially in those with fertility problems. In this review, indications, surgical techniques for the repair of CUA according to their classification, and fertility and pregnancy outcomes before and after surgery will be thoroughly reviewed.

Perinatal exposure to androgen excess and the effects on the rat uterine estradiol responsiveness

Androgen exposure during sexual development induces alterations in steroidal target tissues. The objective of this study was to evaluate the uterine responsiveness to estradiol after perinatal androgenization. Pregnant Wistar rats were exposed to corn oil or testosterone propionate at 0.05, 0.1, or 0.2 mg/kg from gestational day 12 until postnatal day 21. Female offspring was challenged with estradiol (E₂ ) after weaning (0.4 mg/kg) and at adulthood (10 or 100 µg/day), when the pituitary response was also evaluated. At adulthood, control and 0.05 mg/kg groups presented a uterine weight increment when exposed to 100 µg/day of E₂ , 0.1 mg/kg group only responded to 10 µg/day of E₂ , and the 0.2 mg/kg group showed increased uterine weight at both doses. The pituitary weight was similarly increased after estradiol stimulation in all experimental groups. In conclusion, testosterone propionate exposure induced an abnormal stimulation of uterine tissue growth by estrogen stimulus without affecting pituitary response. More studies are needed to clarify whether these alterations are capable of impairing the reproductive capacity of the female tract. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1460-1468, 2016.

Steroid hormones in bovine oviductal fluid during the estrous cycle

Ovarian steroid hormones are major regulators of the physiology of the oviduct and reproductive events occurring within the oviduct. To establish a whole steroid profiling of the bovine oviductal fluid (OF) during the estrous cycle, contralateral and ipsilateral (to the corpus luteum or preovulatory follicle) oviducts were classified into four stages of the estrous cycle (n = 18-27 cows per stage): postovulatory (Post-ov), mid-luteal (Mid-lut), late luteal (Late-lut), and preovulatory on the basis of the ovarian morphology and intrafollicular steroid concentrations. Steroids were extracted from pools of 150 to 200 μL OF (three to 10 cows per pool; three to four pools per "stage × side" group), purified, fractioned by high-performance liquid chromatography, and analyzed by gas chromatography coupled with tandem mass spectrometry. The concentrations of progesterone (P4) in ipsilateral OF increased from Post-ov (56.9 ± 13.4 ng/mL) to Mid-lut (120.3 ± 34.3 ng/mL), then decreased from Late-lut (76.7 ± 1.8 ng/mL) to Pre-ov (6.3 ± 1.7 ng/mL), and were four to 16 times higher than in contralateral OF. Most P4 metabolites followed similar patterns of variation. Concentrations of 17beta-estradiol (E2) were significantly higher at Pre-ov (290.5 ± 63.2 pg/mL) compared with all other stages (<118.3 pg/mL), with no difference regarding the side of ovulation. Concentrations of androstenedione displayed a pattern similar to that of E2, whereas other androgens, estrone, and corticoids did not vary between stages or sides. In conclusion, a highly concentrated and fluctuating hormonal environment was evidenced in the bovine OF. These results could be useful to improve media for IVF, embryo development, and culture of oviductal cells.

Neonatal Estrogen Receptor β Is Important in the Permanent Inhibition of Epithelial Cell Proliferation in the Mouse Uterus

Estrogen receptor α (ERα) plays a pivotal role in the mouse uterine and vaginal epithelial cell proliferation stimulated by estrogen, whereas ERβ inhibits cell proliferation. ERβ mRNA is expressed in neonatal uteri and vaginae; however, its functions in neonatal tissues have not been ascertained. In this study, we investigated the ontogenic mRNA expression and localization of ERβ, and its roles in cell proliferation in neonatal uteri and vaginae of ERβ knockout (βERKO) mice. ERβ mRNA and protein were abundant in the uterine and vaginal epithelia of 2-day-old mice and decreased with age. In uterine and vaginal epithelia of 2-day-old βERKO mice, cell proliferation was greater than that in wild-type animals and in uterine epithelia of 90- and 365-day-old βERKO mice. In addition, p27 protein, known as a cyclin-dependent kinase inhibitor, was decreased in the uteri of 90- and 365-day-old βERKO mice. Inhibition of neonatal ERs by ICI 182780 (an ER antagonist) treatment stimulated cell proliferation and decreased p27 protein in the uterine luminal epithelium of 90-day-old mice but not in the vaginal epithelium. These results suggest that neonatal ERβ is important in the persistent inhibition of epithelial cell proliferation with accumulation of p27 protein in the mouse uterus. Thus, suppression of ERβ function in the uterine epithelium during the neonatal period may be responsible for a risk for proliferative disease in adults.

Combined repeated dose and reproductive/developmental toxicity screening test of 4-methoxy-2-nitroaniline in rats

4-Methoxy-2-nitroaniline (4M2NA) is widely used as an intermediate for the synthesis of dyes, pigments and other chemical compounds. Since 4M2NA has amino-group and nitro-group on the benzene ring, it was expected that it induced obvious hemolytic anemia. We conducted a combined repeated dose and reproductive/developmental toxicity screening test according to Organisation for Economic Co-operation and Development (OECD) Test Guideline No. 422 (OECD TG 422) to enrich the toxic information and ensure the safety of 4M2NA. 4M2NA was administered to Crl:CD(SD) male and female rats by gavage at 0, 12.5, 75 or 450 mg/kg/day for 42 to maximum of 54 days through pre-mating, mating, pregnancy and lactation periods. An extramedullary hematopoiesis and congestion in spleen, and higher reticulocyte ratio were noted in only females at 450 mg/kg/day without decreased anemic parameters in the hematological examination. Hypertrophy of centrilobular hepatocytes in both sexes was observed with increased relative liver weight at 450 mg/kg/day. Furthermore, the diffuse follicular cell hypertrophy of the thyroid was observed in females at 450 mg/kg/day. No abnormalities were detected in the reproductive indices of copulation, delivery or fetal viability. We concluded the no-observed-adverse-effect level (NOAEL) for repeated-dose toxicity was 75 mg/kg/day based on the trace evidences of hemolytic anemia, and the NOAEL for reproductive/developmental toxicity as 450 mg/kg/day based on no toxicological concerns for reproductive endpoints. The hemolytic anemia was much milder than expected. Thus, we discussed the reason of this much less hemolytic effect from the point of view of the structural characteristics of 4M2NA.

Altered gene expression patterns during the initiation and promotion stages of neonatally diethylstilbestrol-induced hyperplasia/dysplasia/neoplasia in the hamster uterus

Neonatal treatment of hamsters with diethylstilbestrol (DES) induces uterine hyperplasia/dysplasia/neoplasia (endometrial adenocarcinoma) in adult animals. We subsequently determined that the neonatal DES exposure event directly and permanently disrupts the developing hamster uterus (initiation stage) so that it responds abnormally when it is stimulated with estrogen in adulthood (promotion stage). To identify candidate molecular elements involved in progression of the disruption/neoplastic process, we performed: (1) immunoblot analyses and (2) microarray profiling (Affymetrix Gene Chip System) on sets of uterine protein and RNA extracts, respectively, and (3) immunohistochemical analysis on uterine sections; all from both initiation stage and promotion stage groups of animals. Here we report that: (1) progression of the neonatal DES-induced hyperplasia/dysplasia/neoplasia phenomenon in the hamster uterus involves a wide spectrum of specific gene expression alterations and (2) the gene products involved and their manner of altered expression differ dramatically during the initiation vs. promotion stages of the phenomenon.

Effects of ovarian hormones on internal circadian organization in rats

The circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus is the central pacemaker driving rhythms in endocrine physiology. Gonadal steroid hormones affect behavioral rhythms and clock gene expression. However, the impact of fluctuating ovarian steroid levels during the estrous cycle on internal circadian organization remains to be determined. Further, it is not known if steroid hormone depletion, as in menopause, affects the timing system. To determine the influence of estrous cycle stage and steroid depletion on circadian organization, we measured clock gene expression in the SCN and peripheral tissues from cycling and ovariectomized (OVX) period1-luciferase (per1-luc) transgenic rats. The estrous cycle had modest effects on mean phase and phase distribution of per1-luc expression in the SCN. Surprisingly, peak per1-luc expression in the SCN was widely distributed mainly at night, regardless of cycle stage, an effect eliminated by OVX. Treatment of SCN tissue explants with ovarian steroids did not significantly affect per1-luc expression, suggesting that brain regions outside the SCN mediate the phasic effects of steroids. Our data demonstrate that estrous cycle stage has tissue-dependent effects on the phase of per1-luc expression, phase synchrony among oscillators, and the phase relationship between some peripheral clocks and the light-dark cycle. They also reveal that steroid hormone depletion following OVX alters the timing system, suggesting that the decline in hormone levels, common during the transition to menopause, may be associated with irregular internal circadian organization. This effect on the timing system could contribute to the behavioral and physiological changes associated with this transition.

Excess androgen during perinatal life alters steroid receptor expression, apoptosis, and cell proliferation in the uteri of the offspring

Exposure to environmental chemicals may contribute to reproductive disorders, especially when it occurs in critical periods of development. The female reproductive system can be a target for androgens derived from environmental contaminants or pathological conditions. The purpose of this study was to assess the long-term effects of androgens on uterine tissue after maternal exposure limited to the time of gestation and lactation. Pregnant Wistar rats were treated with testosterone propionate (TP) at 0.05 mg/kg, 0.1 mg/kg, 0.2 mg/kg or corn oil (vehicle), s.c., from gestational day 12 until the end of lactation. The results show changes in the pattern of expression of receptors for estrogen, progesterone, and androgen at all doses tested, and decreases in both apoptosis and cell proliferation indices at 0.1 and 0.2 mg/kg. We conclude that early TP exposure, under these experimental conditions, causes changes in cellular and molecular parameters that are essential for normal uterine function in the adult.

Melatonin and ethanol intake exert opposite effects on circulating estradiol and progesterone and differentially regulate sex steroid receptors in the ovaries, oviducts, and uteri of adult rats

Chronic ethanol intake is associated with sex hormone disturbances, and it is well known that melatonin plays a key role in regulating several reproductive processes. We report the effects of ethanol intake and melatonin treatment (at doses of 100 μg/100 g BW/day) on sex hormones and steroid receptors in the ovaries, oviducts and uteri of ethanol-preferring rats. After 150 days of treatment, animals were euthanized, and tissue samples were harvested to evaluate androgen, estrogen, progesterone and melatonin receptor subunits (AR, ER-α and ER-β, PRA, PRB and MT1R, respectively). Melatonin decreased estradiol (E2) and increased progesterone (P4) and 6-sulfatoxymelatonin (6-STM), while an ethanol-melatonin combination reduced both P4 and E2. Ovarian AR was not influenced by either treatment, and oviduct AR was reduced after ethanol-melatonin combination. Oviduct ER-α, ER-β and uterine ER-β were down-regulated by either ethanol or melatonin. Conversely, ovarian PRA and PRB were positively regulated by ethanol and ethanol-melatonin combination, whereas PRA was down-regulated in the uterus and oviduct after ethanol consumption. MT1R was increased in ovaries and uteri of melatonin-treated rats. Ethanol and melatonin exert opposite effects on E2 and P4, and they differentially regulate the expression of sex steroid receptors in female reproductive tissues.

AHCYL1 is mediated by estrogen-induced ERK1/2 MAPK cell signaling and microRNA regulation to effect functional aspects of the avian oviduct

S-adenosylhomocysteine hydrolase-like protein 1 (AHCYL1), also known as IP(3) receptor-binding protein released with IP(3) (IRBIT), regulates IP(3)-induced Ca(2+) release into the cytoplasm of cells. AHCYL1 is a critical regulator of early developmental stages in zebrafish, but little is known about the function of AHCYL1 or hormonal regulation of expression of the AHCYL1 gene in avian species. Therefore, we investigated differential expression profiles of the AHCYL1 gene in various adult organs and in oviducts from estrogen-treated chickens. Chicken AHCYL1 encodes for a protein of 540 amino acids that is highly conserved and has considerable homology to mammalian AHCYL1 proteins (>94% identity). AHCYL1 mRNA was expressed abundantly in various organs of chickens. Further, the synthetic estrogen agonist induced AHCYL1 mRNA and protein predominantly in luminal and glandular epithelial cells of the chick oviduct. In addition, estrogen activated AHCYL1 through the ERK1/2 signal transduction cascade and that activated expression of AHCYL1 regulated genes affecting oviduct development in chicks as well as calcium release in epithelial cells of the oviduct. Also, microRNAs, miR-124a, miR-1669, miR-1710 and miR-1782 influenced AHCYL1 expression in vitro via its 3'-UTR which suggests that post-transcriptional events are involved in the regulation of AHCYL1 expression in the chick oviduct. In conclusion, these results indicate that AHCYL1 is a novel estrogen-stimulated gene expressed in epithelial cells of the chicken oviduct that likely affects growth, development and calcium metabolism of the mature oviduct of hens via an estrogen-mediated ERK1/2 MAPK cell signaling pathway.

Identification of quiescent, stem-like cells in the distal female reproductive tract

In fertile women, the endometrium undergoes regular cycles of tissue build-up and regression. It is likely that uterine stem cells are involved in this remarkable turn over. The main goal of our current investigations was to identify slow-cycling (quiescent) endometrial stem cells by means of a pulse-chase approach to selectively earmark, prospectively isolate, and characterize label-retaining cells (LRCs). To this aim, transgenic mice expressing histone2B-GFP (H2B-GFP) in a Tet-inducible fashion were administered doxycycline (pulse) which was thereafter withdrawn from the drinking water (chase). Over time, dividing cells progressively loose GFP signal whereas infrequently dividing cells retain H2B-GFP expression. We evaluated H2B-GFP retaining cells at different chase time points and identified long-term (LT; >12 weeks) LRCs. The LT-LRCs are negative for estrogen receptor-α and express low levels of progesterone receptors. LRCs sorted by FACS are able to form spheroids capable of self-renewal and differentiation. Upon serum stimulation spheroid cells are induced to differentiate and form glandular structures which express markers of mature Műllerian epithelial cells. Overall, the results indicate that quiescent cells located in the distal oviduct have stem-like properties and can differentiate into distinct cell lineages specific of endometrium, proximal and distal oviduct. Future lineage-tracing studies will elucidate the role played by these cells in homeostasis, tissue injury and cancer of the female reproductive tract in the mouse and eventually in man.

Defeminization of brain functions by a single injection of estrogen receptor α or β agonist in neonatal female rats

Sexual differentiation of brain function is regulated by estrogen in the perinatal period of rodents. However, the role of the estrogen receptor subtypes ERα and ERβ is still in question. Accordingly, the effects of neonatal treatment with the ERα agonist propyl pyrazole triol (PPT) or the ERβ agonist diarylpropionitrile (DPN) on female reproductive functions were investigated in rats. Female rats were injected subcutaneously with 100-500 µg/10 g body weight (b.w.) PPT or DPN, 100 µg/10 g b.w. estradiol (E(2)), or saline at day 5 (birth day = day 1), and then vaginal opening and vaginal smears were examined. On day 60, their ovaries were removed and lordosis behavior was observed after subcutaneous implantation of a silicon tube containing E(2). As a result, in most PPT and all E(2) rats, vaginal opening was advanced and an irregular estrous cycle was observed. In contrast, in most rats of the DPN groups, vaginal opening was comparable to that of the control and there was a regular estrous cycle. Lordosis tests revealed that the mean lordosis quotients (LQs) in the 250- and 500-µg PPT groups was lower than in the saline group, but higher than in the E(2) group. Mean LQs in all DPN groups were comparable to those in the saline group. These results suggest that ERα plays a major role in masculinization of the system regulating the estrous cycle in the rat brain. In behavioral defeminization of the lordosis-regulation system, ERα was also found to be the main target of estrogen.

ERBB receptor feedback inhibitor 1: identification and regulation by estrogen in chickens

The ERBB receptor feedback inhibitor 1 (ERRFI1) is a scaffolding adaptor protein, that plays a pivotal role in the epidermal growth factor receptor (EGFR) cell signaling cascade as a negative regulator affecting many important physiological processes. It was recently reported that ERRFI1 is a critical regulator of the response of the endometrium to estrogen regulation of tissue homeostasis in mice. But, very little is known about ERRF11 and hormonal regulation of the ERRFI1 gene in chickens. Therefore, in the present study, ERRFI1 gene was cloned and its differential expression profile analyzed at different embryonic stages, in various adult organs, and in oviducts from estrogen-treated chickens. Chicken ERRFI1 has an open-reading frame of 2848 nucleotides that encode for a protein of 465 amino acids that has considerable homology to mammalian ERRFI1 proteins (>62% identity). Importantly, ERRFI1 mRNA is abundantly distributed in various organs from chickens. We then determined that DES (diethylstilbestrol, a synthetic nonsteroidal estrogen) induced ERRFI1 mRNA and protein predominantly in luminal and glandular epithelial cells of the oviduct. Further, we determined whether microRNAs, specifically miR-200b, miR-429 and miR-1639, influence ERRFI1 expression via its 3'UTR and found that it does not directly target the 3'UTR of ERRFI1 mRNA. Therefore, it is unlikely that post-transcriptional regulation influences ERRFI1 expression in the chicken oviduct. In conclusion, our results indicate that ERRFI1 is a novel estrogen-stimulated gene expressed in epithelial cells of the chicken oviduct that likely plays an important role in oviduct growth and differentiation during early development of the chicken.

Pathological study for the effects of in utero and postnatal exposure to diesel exhaust on a rat endometriosis model

Previous studies have shown that prenatal and postnatal exposure to diesel exhaust (DE), which is known to be one of the main constituents of air pollution, enhances the persistence of endometriosis in a rat model. The aim of this study is to investigate the pathological changes induced by DE exposure in a rat model of endometriosis. Pregnant Sprague-Dawley rats were exposed to DE or clean air beginning on gestational day 2 and neonatal rats were persistently exposed to DE or clean air. Endometriosis was induced by autotransplantation of endometrium onto the peritoneum of eight-week-old female offspring. Endometriotic lesions were examined at 7 and 14 days post-transplantation. As a result, infiltration of activated mast cells remained in deeper area of peritoneal tissue around the endometriosis model compared to the control group at 14 days post-autotransplantation. In the DE exposure group, 14 days post-transplant, the remaining lesions contained fibroblasts and activated mast cells, which were surrounded by collagen fibers. The data showed that prenatal and postnatal DE exposure enhances the activation of mast cells and prolongs the persistence of collagen fibers in the induced rat model of endometriosis.

Differential expression of alpha 2 macroglobulin in response to dietylstilbestrol and in ovarian carcinomas in chickens

BACKGROUND

Alpha 2 macroglobulin (A2M; also known as ovostatin), a homotetrameric protein with four disulfide-linked subunits, has the unique feature of inactivating/inhibiting most known proteases including serine-, threonine-, cysteine-, aspartic- and metalloproteases. In chickens, A2M has been identified and characterized biochemically, but little is known of its functional role(s) in the oviduct, hormonal regulation of expression or its expression in ovarian carcinomas in chickens. Therefore, we investigated estrogen regulation of A2M gene expression during development of the chicken oviduct, and its expression in normal and cancerous ovaries from chickens.

METHODS

To determine tissue-specific expression of A2M in chickens, we collected various organs from male and female chickens and performed RT-PCR analyses. To examine A2M gene expression in the oviduct of 1-week-old female chicks that received a subcutaneous implant of 15 mg DES in the abdominal region for 20 days, we performed RT-PCR, qPCR and in situ hybridization analyses using cDNAs from control- (n=5) and DES-treated oviducts (n=5), and then each segment of the oviduct from DES-treated chicks. To determine if A2M is a biomarker of ovarian cancer in hens, we collected cancerous (n=10) ovaries from a total of 136 chickens which had completely stopped egg-laying and performed RT-PCR and in situ hybridization analyses.

RESULTS

We found that A2M is most abundant in the chicken oviduct, specifically luminal (LE) and glandular epithelia (GE), but it was not detected in any other tissues of either sex. We then determined that DES (dietylstilbestrol, a synthetic nonsteroidal estrogen) increased A2M mRNA only in LE and GE of the oviduct of chicks. Further, expression of A2M was most abundant in GE of endometrioid adenocarcinoma of cancerous, but not normal ovaries of hens.

CONCLUSIONS

Collectively, results of the present study indicate that A2M is novel estrogen-stimulated gene expressed in LE and GE of the chicken oviduct and may be used for monitoring effects of therapies for ovarian cancer in laying hens.

A helminth cestode parasite express an estrogen-binding protein resembling a classic nuclear estrogen receptor

The role of an estrogen-binding protein similar to a known mammalian estrogen receptor (ER) is described in the estradiol-dependent reproduction of the helminth parasite Taenia crassiceps. Previous results have shown that 17-β-estradiol induces a concentration-dependent increase in bud number of in vitro cultured cysticerci. This effect is inhibited when parasites are also incubated in the presence of an ER binding-inhibitor (tamoxifen). RT-PCR assays using specific oligonucleotides of the most conserved ER sequences, showed expression by the parasite of a mRNA band of molecular weight and sequence corresponding to an ER. Western blot assays revealed reactivity with a 66 kDa protein corresponding to the parasite ER protein. Tamoxifen treatment strongly reduced the production of the T. crassiceps ER-like protein. Antibody specificity was demonstrated by immunoprecipitating the total parasite protein extract with anti-ER-antibodies. Cross-contamination by host cells was discarded by flow cytometry analysis. ER was specifically detected on cells expressing paramyosin, a specific helminth cell marker. Parasite cells expressing the ER-like protein were located by confocal microscopy in the subtegumental tissue exclusively. Analysis of the ER-like protein by bidimensional electrophoresis and immunoblot identified a specific protein of molecular weight and isoelectric point similar to a vertebrates ER. Sequencing of the spot produced a small fragment of protein similar to the mammalian nuclear ER. Together these results show that T. crassiceps expresses an ER-like protein which activates the budding of T. crassiceps cysticerci in vitro. To the best of our knowledge, this is the first report of an ER-like protein in parasites. This finding may have strong implications in the fields of host-parasite co-evolution as well as in sex-associated susceptibility to this infection, and could be an important target for the design of new drugs.

Melatonin reduces LH, 17 beta-estradiol and induces differential regulation of sex steroid receptors in reproductive tissues during rat ovulation

BACKGROUND

Melatonin is associated with direct or indirect actions upon female reproductive function. However, its effects on sex hormones and steroid receptors during ovulation are not clearly defined. This study aimed to verify whether exposure to long-term melatonin is able to cause reproductive hormonal disturbances as well as their role on sex steroid receptors in the rat ovary, oviduct and uterus during ovulation.

METHODS

Twenty-four adult Wistar rats, 60 days old (+/-250 g) were randomly divided into two groups. Control group (Co): received 0.9% NaCl 0.3 mL+95% ethanol 0.04 mL as vehicle; Melatonin-treated group (MEL): received vehicle+melatonin [100 μg/100 g BW/day] both intraperitoneally during 60 days. All animals were euthanized by decapitation during the morning estrus at 4 a.m.

RESULTS

Melatonin significantly reduced the plasma levels of LH and 17 beta-estradiol, while urinary 6-sulfatoximelatonin (STM) was increased at the morning estrus. In addition, melatonin promoted differential regulation of the estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR) and melatonin receptor (MTR) along the reproductive tissues. In ovary, melatonin induced a down-regulation of ER-alpha and PRB levels. Conversely, it was observed that PRA and MT1R were up-regulated. In oviduct, AR and ER-alpha levels were down-regulated, in contrast to high expression of both PRA and PRB. Finally, the ER-beta and PRB levels were down-regulated in uterus tissue and only MT1R was up-regulated.

CONCLUSIONS

We suggest that melatonin partially suppress the hypothalamus-pituitary-ovarian axis, in addition, it induces differential regulation of sex steroid receptors in the ovary, oviduct and uterus during ovulation.

Generation of human female reproductive tract epithelium from human embryonic stem cells

Background

Recent studies have identified stem/progenitor cells in human and mouse uterine epithelium, which are postulated to be responsible for tissue regeneration and proliferative disorders of human endometrium. These progenitor cells are thought to be derived from Müllerian duct (MD), the primordial female reproductive tract (FRT).

Methodology/Principal Findings

We have developed a model of human reproductive tract development in which inductive neonatal mouse uterine mesenchyme (nMUM) is recombined with green fluorescent protein (GFP)-tagged human embryonic stem cells (hESCs); GFP-hESC (ENVY). We demonstrate for the first time that hESCs can be differentiated into cells with a human FRT epithelial cell phenotype. hESC derived FRT epithelial cells emerged from cultures containing MIXL1⁺ mesendodermal precursors, paralleling events occurring during normal organogenesis. Following transplantation, nMUM treated embryoid bodies (EBs) generated epithelial structures with a typical MD phenotype that expressed the MD markers PAX2, HOXA10. Functionally, the hESCs derived FRT epithelium responded to exogenous estrogen by proliferating and secreting uterine-specific glycodelin A (GdA).

Conclusions/Significance

These data show nMUM can induce differentiation of hESC to form the FRT epithelium. This may provide a model to study early developmental events of the human FRT.

Estrogen-dependent transactivation of amphioxus steroid hormone receptor via both estrogen and androgen response elements

Estrogens are necessary for ovarian differentiation during critical developmental windows in most vertebrates and promote the growth and differentiation of the adult female reproductive system. Estrogen actions are largely mediated through the estrogen receptors (ERs), which are ligand-activated transcription factors. To understand the molecular evolution of sex steroid hormone receptors, we isolated cDNAs encoding two steroid receptors from Japanese amphioxus, Branchiostoma belcheri: an ER ortholog and a ketosteroid receptor (SR) ortholog. Reporter gene assays revealed that the SR ortholog has molecular functions similar to those of the vertebrate ER. Surprisingly, the ER ortholog is an estrogen-insensitive repressor of SR-mediated transcription. Furthermore, we found that the SR ortholog can bind to both estrogen-responsive elements (EREs) and androgen-responsive elements (AREs) and mediates transcriptional activation by estrogens through both types of elements. Our findings suggest that the ancestral SR, but not ER, could bind estrone and induce the ERE- and ARE-dependent transactivation and that it gained the ability to be regulated by ketosteroid and recognize ARE specifically before jawless vertebrates split. These results highlight the importance of comparative experimental approaches for the evolutionary study of endocrine systems.

The role of steroid hormones in the NF1 phenotype: focus on pregnancy

The Neurofibromatosis Type 1 (NF1) gene functions as a tumor suppressor gene. Loss of its protein, neurofibromin, in the autosomal dominant disorder NF1 is associated with peripheral nervous system tumors, particularly neurofibromas, benign lesions in which the major cell type is the Schwann Cell (SC). Benign and malignant human tumors found in NF1 patients are heterogeneous with respect to their cellular composition. The number and size of neurofibromas in NF1 patients has been shown to increase during pregnancy, with, in some cases, post-partum regression, which suggests hormonal involvement in this increase. However, in this review, we consider evidence from the literature that both direct hormonal influence on tumor growth and on angiogenesis may contribute to these effects.

Influence of hormones and hormone metabolites on the growth of Schwann cells derived from embryonic stem cells and on tumor cell lines expressing variable levels of neurofibromin

Loss of neurofibromin, the protein product of the tumor suppressor gene neurofibromatosis type 1 (NF1), is associated with neurofibromas, composed largely of Schwann cells. The number and size of neurofibromas in NF1 patients have been shown to increase during pregnancy. A mouse embryonic stem cell (mESC) model was used, in which mESCs with varying levels of neurofibromin were differentiated into Schwann-like cells. NF1 cell lines derived from a malignant and a benign human tumor were used to study proliferation in response to hormones. Estrogen and androgen receptors were not expressed or expressed at very low levels in the NF1+/+ cells, at low levels in NF1+/-cells, and robust levels in NF1-/-cells. A 17beta-estradiol (E2) metabolite, 2-methoxy estradiol (2ME2) is cytotoxic to the NF1-/- malignant tumor cell line, and inhibits proliferation in the other cell lines. 2ME2 or its derivatives could provide new treatment avenues for NF1 hormone-sensitive tumors at times of greatest hormonal influence.

Relaxin (RLX) and estrogen affect estrogen receptor α, vascular endothelial growth factor, and RLX receptor expression in the neonatal porcine uterus and cervix

The porcine female reproductive tract undergoes estrogen receptor (ER) α-dependent development after birth (postnatal day=PND 0), the course of which can determine adult uterine function. Uterotrophic effects of relaxin (RLX) in the porcine neonate are age specific and may involve ER activation. Here, objectives were to determine effects of RLX and estrogen administered from birth on uterine and cervical growth and expression of ERα, vascular endothelial growth factor (VEGF), and the RLX receptor (RXFP1). On PND 0, gilts were treated with the antiestrogen ICI 182 780 (ICI) or vehicle alone and, 2 h later, were given estradiol-17β (E) or porcine RLX for 2 days. Neither RLX nor E affected uterine wet weight or protein content on PND 2. However, RLX, but not E, increased cervical wet weight and protein content when compared with controls. Pretreatment with ICI did not inhibit RLX-stimulated cervical growth. Uterine and cervical ERα increased in response to RLX, but not E. Both RLX and E increased VEGF in the uterus and cervix on PND 2. Pretreatment with ICI increased VEGF in both tissues and increased RLX-induced cervical VEGF. In the uterus E, but not RLX, increased RXFP1 mRNA. In the cervix, E increased RXFP1 gene expression whereas RLX decreased it. Results indicate that the neonatal uterus and cervix are sensitive to E and RLX and that growth responses to RLX in these tissues differ by PND 2. Effects of RLX on uterine and cervical ERα and VEGF expression may be important for neonatal reproductive tract development.

Evaluating rodent vaginal and uterine histology in toxicity studies

Interpreting histopathology of the female rodent reproductive tract can be challenging in toxicity studies. However, diagnosis can be relatively uncomplicated with an understanding of the relationship between form and function. We describe this relationship for the rodent uterus and vagina and discuss some strategies to simplify diagnosis.

Immunoendocrine aspects of endometrial function and implantation

Effective ovarian and uterine function relies on a complex interplay between the endocrine and immune systems. It is generally accepted that in reproductive tissues, oestradiol and progesterone have pro- and anti-inflammatory activities respectively and, in this regard, the paracrine effects of the sex steroids on the ovary are similar to the endocrine effects on the uterus. Ovarian leukocyte recruitment and cytokine release are central to follicle development, ovulation and corpus luteum function. At the uterine level, the cyclical changes in sex steroids regulate the number and distribution of endometrial and decidual immune cells as well as other immune signalling and surveillance factors. The uterine mucosa is unique, in that it must tolerate sperm and the allogeneic blastocyst in a way that does not compromise uterine immune surveillance against bacteria, yeast and viruses. Crosstalk between the sex steroids and immune mediators (systemic and local) are central to these functions, and this article will review these mechanisms and their importance for successful reproductive function and pregnancy success.

Estrogen-induced upregulation of AR expression and enhancement of AR nuclear translocation in mouse fallopian tubes in vivo

Female mice lacking AR display alterations in ovarian and uterine function. However, the biology of AR in the fallopian tube is not fully understood. To gain an insight into potential roles of AR in this tissue, we demonstrated that eCG treatment increased AR expression in a time-dependent manner and subsequent treatment with hCG decreased AR expression in mouse fallopian tubes. This expression pattern was positively associated with 17beta-estradiol and testosterone levels in vivo. Immunohistochemical analysis of fallopian tube epithelial cells revealed that nuclear localization of AR increased in parallel with decreased AR in the cytoplasm following eCG treatment. Moreover, we found that treatment with flutamide upregulated AR expression in immature mice in association with a decrease in serum testosterone levels, whereas the same treatment resulted in downregulation of AR expression in gonadotropin-stimulated mice with concomitant decreases in serum 17beta-estradiol concentrations, suggesting that androgen differs from estrogen in the regulation of AR expression. Furthermore, we demonstrated that DES increased both AR protein expression and nuclear location over a 48-h time course. DHT had rapid effects, with induction of AR expression and translocation at 6 h after injection, but unlike DES it had prolonged efficacy. In addition, we provided direct in vivo evidence that nuclear protein interaction between AR and p21(Cip1), a previously reported AR-regulated gene, was enhanced by gonadotropin stimulation. To our knowledge, this study provides the first demonstration to illustrate that estrogen as a principal regulator may contribute to regulate and activate AR in the fallopian tubes in vivo.