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Abstract

An electromagnetic field (EMF) has been found to affect reproductive processes in females. The aim of this study was to determine the effect of low, non-ionizing EMF radiation on the steroidogenic activity of myometrium collected from pigs during the fetal peri-implantation period. Myometrial slices were treated with an EMF (50 and 120 Hz, 2 and 4 h of incubation) and examined for the aromatase cytochrome P450 17α-hydroxylase/C17-20lyase (CYP17A1) and 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (HSD3B1) mRNA transcript abundance, cytochrome P450c17 and 3βHSD protein abundance and the secretion of androstenedione (A4) and testosterone (T). To determine whether progesterone (P4) functions as a protectant from EMF radiation, the selected slices were treated with P4. In slices incubated without P4, EMF at 50 Hz altered cytochrome P450c17 protein abundance (4 h), HSD3B1 mRNA transcript abundance (4 h) and A4 release (2 h) as well as T release (2 h) in P4-treated slices. The EMF at 120 Hz in non P4-treated slices altered A4 release (2 and 4 h) whereas in P4-treated slices altered CYP17A1 mRNA transcript abundance (4 h), 3βHSD protein abundance (4 h), A4 (4 h) and T release (2 h). In conclusion, EMF radiation in the myometrium collected during the peri-implantation period alters the CYP17A1 and HSD3B1 mRNA transcript and encoded protein abundance, and androgen release due to the time of treatment and P4 presence or absence. The P4 did not function directly as an obvious protector against EMF radiation in the myometrium of pigs during the fetal peri-implantation period.

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... As a result, Electric Energy (EEIX) and magnetic energy propagate to space through EMW with the periodic transformation of EF and MF [8][9][10]. The EMW is a shear wave, and the MF, EF, and traveling direction of the EMW are perpendicular to one another [11][12][13]. The propagation of EMW includes ground waves propagating and airwaves propagating. ...
... Equations (9) and (10) suggest that the VMP and ESP are related to the four theorems in Section 2.1 and, thus, can be applied to them. The specific forms are shown in Equations (11) and (12). ...
... In Equation (12), the letters share the same meaning as those in the above equations. ...
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... Nevertheless, the molecular background of these changes is hardly understood. Due to the fact that the success of early pregnancy is ensured by a unique embryo-maternal dialog involving the action of steroid hormones [9,10], it was proposed that jeopardizing effects of the EMF treatment on pregnancy development might be coupled with the altered uterine steroidogenic activity [7,8,11,12]. Indeed, recent in vitro studies on a pig model demonstrated that the EMF treatment (50 and 120 Hz, 8 mT, 2 and 4 h) induces alterations in the synthesis and secretion of steroid hormones by the uterine tissues, including the myometrium [7,8,11,12]. ...
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... Endometrial slices were placed in 24-well culture plates and covered with pre-incubation medium (1 mL, M199, Sigma Aldrich, St. Louis, MO, USA, 0.1 % BSA, Carl Roth GmBH + Co KG, Mühlburg, Karlsruhe, Germany, 1% antibioticantimycotic solution) and then pre-incubated for 2 h in 37 • C, 95 % O 2 and 5 % CO 2 in a water-shaking bath, as previously described (Koziorowska et al., 2018;Franczak et al., 2020). After pre-incubation, the culture media were discarded and replaced with the fresh media. ...
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Past studies of the oviducts have documented oviductal steroid production during the oestrous cycle in pigs. The present study examined whether the pig oviducts are the source of steroid hormones during early pregnancy. In the ampulla and isthmus, the expression of 3β-hydroxysteroid dehydrogenase (3βHSD) and aromatase cytochrome P450 (CYP19) mRNA by real-time PCR, cellular localization and quantities of the studied proteins by immunofluorescence and Western blot analysis, and concentration of steroid hormones in oviductal flushings by radioimmunoassay, were studied. The expression of 3βHSD in the ampulla and isthmus was correlated (r = 0.89) and higher on Days 2-3 and 15-16 than on Days 10-11 and 12-13. CYP19 expression was elevated in the ampulla on Days 2-3, 10-11 and 15-16 and in the isthmus on Days 2-3 vs. the other days studied. The studied proteins were localized in oviductal epithelial cells. In the ampulla, the quantity of 3βHSD protein did not change, and was greater in the isthmus on Days 2-3 vs. Days 12-13 of pregnancy. The P450arom protein quantity increased in the ampulla on Days 2-3 vs. Days 10-11 and 15-16 and vs. Days 10-11 and 12-13 in the isthmus. The concentrations of progesterone and androstenedione in oviductal flushings were lowest on Days 12-13 and on Days 2-3 and 15-16, respectively, while oestradiol-17β and oestrone levels did not change. Porcine oviducts are the sources of steroid hormones during early pregnancy. The expression of steroidogenic enzymes primarily increases during the embryos presence in the oviduct, i.e., on Days 2-3 of pregnancy.
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An electromagnetic field (EMF) of extremely low frequency may affect physiological processes in mammals. The aim of the present study was to determine the effect of an EMF on the synthesis and secretion of oestradiol-17β (E2) in the porcine uterus. Endometrial and myometrial slices were harvested on days 12-13 of the oestrous cycle and exposed in vitro to an EMF (50 and 120 Hz, 8 mT) for 2 and 4 h in the presence or absence of progesterone (P4). Subsequently, the incubation media were used to determine the concentration of E2 with RIA. Tissues fragments were used to study the expression of CYP19A3 mRNA using Real-Time PCR and the abundance of P450 aromatase using Western Blotting. The 50-Hz EMF increased E2 release from the endometrium and the myometrium at both time points of in vitro incubation. A 120-Hz EMF decreased the endometrial secretion of E2 after 2 h of incubation and did not affect E2 secretion after 4 h. In the myometrium, the 120-Hz EMF increased E2 secretion after 4 h of incubation. In P4-treated uterine fragments, no significant EMF exposition-related changes were observed. Only myometrial fragments incubated in the presence of P4 at 120-Hz EMF (4 h) released higher amounts of E2 due to EMF treatment. The 50-Hz EMF exposure did not change the CYP19A3 mRNA expression in endometrial fragments incubated in the presence or absence of P4. In myometrial fragments, the highest CYP19A3 mRNA expression was observed in fragments not exposed to the 50-Hz EMF and P4-treated tissues compared to that in fragments exposed to 50 Hz EMF and incubated with or without P4 and control (no EMF and no P4) fragments. The EMF at 120 Hz decreased basal endometrial CYP19A3 mRNA expression and did not change the expression in the P4-treated endometrium. In the myometrium, the EMF at 120 Hz increased CYP19A3 mRNA expression in slices incubated without P4 and had no effect in the presence of P4. The EMF exposure (50 and 120 Hz) did not affect P450 aromatase abundance in either the endometrium or the myometrium. In conclusion, the EMF induces changes in the synthesis and release of E2 in uterine tissues harvested during days 12-13 of the oestrous cycle. These changes are related to the EMF frequency used, the time of the exposition and the presence of P4. We suspect that this observed phenomenon might lead to changes in the intrauterine milieu of oestrogen, which is crucial for the proper activity of uterine tissues during the mid-luteal phase of the oestrous cycle.
Article
Purpose: The purpose of this study was to use histological and biochemical methods in order to evaluate changes taking place in the ovaria of rats exposed to the effect of a 900-Megahertz (MHz) electromagnetic field (EMF) in middle and late adolescence. Materials and Methods: Twenty-four 34-day-old female Sprague Dawley rats were assigned equally into control, sham and EMF groups. EMF group rats were exposed to the effect of a 900-MHz EMF for 1 hour a day, at the same time every day between postnatal days 35 and 59, while inside an EMF cage. Sham group rats were kept inside the EMF cage for the same time between postnatal days 35 and 59 without being exposed to any EMF effect. At the end of the study, rats’ ovaria were removed and blood specimens were taken. Right ovarium tissues were subjected to routine histological procedures and stained with hematoxylin and eosin, periodic acid shift and Masson’s trichrome. Follicles were counted in ovarian sections stained with hematoxylin and eosin. The TUNEL method was used to evaluate apoptosis. Left ovarian tissue and blood specimens were investigated biochemically. Results: Histopathological examination of EMF group ovarian tissue revealed thinning in the zona granulosa and theca layers, shrinking in granulose cells, reduced mitotic activity and leukocyte infiltration in the follicles and stroma. Secondary follicle numbers in the EMF group were significantly lower than in the other groups. In terms of biochemistry, EMF and sham group superoxide dismutase, catalase and anti-Mullerian hormone levels and EMF group 3-nitrotirosin values increased significantly compared to the control group. EMF and sham group serum catalase and 8-hydroxy-deoxiguanosine values increased significantly compared to the control group, and EMF group total oxidant status and oxidative stress index values were significantly higher compared to the sham and control groups. Conclusions: 900-MHz EMF applied in middle and late adolescence may cause changes in the morphology and biochemistry of the rat ovarium.
Article
The impact of electromagnetic fields (EMF) on the pineal gland has been described in numerous studies, but many questions still remain unanswered. The aim of the experiment described in this study was to evaluate the effect of EMF on the viability of the pineal gland cells of pig in vitro. Primary culture of the pineal gland cells has been exposed to the influence of an EMF at a frequency of 50 Hz with 1, 2 or 3 hours and for 3 hours every 2 or 3 days. After the experiment, viability of cells was assessed by MTT assay and compared to a control culture not exposed to electromagnetic fields. We noticed that in respect to the control, exposure of the cells to the EMF induced a significant increase in viability of cells at 2 and 3 hours of exposure. After three days of 3-hour exposure to EMF, we observed a significant decrease in cell viability in relation to the control. The results of these studies suggest that EMF can have a significant biological effect on the cells of the pineal gland in a time-dependent exposure to its action.
Article
Studies have suggested that exposure to extremely low frequency electromagnetic fields (ELF-EMF) may be associated with increased risk of adverse birth outcomes. This study tested the hypothesis that close proximity to residential ELF-EMF sources is associated with a reduction in birth weight and increased the risk of low birthweight (LBW), small for gestational age (SGA) and spontaneous preterm birth (SPTB). Closest residential proximity to high voltage cables, overhead power lines, substations or towers during pregnancy was calculated for 140356 singleton live births between 2004 and 2008 in Northwest England. Associations between proximity and risk for LBW, SGA and SPTB were calculated, as well as associations with birth weight directly. Associations were adjusted for maternal age, ethnicity, parity and for part of the population additionally for maternal smoking during pregnancy. Reduced average birth weight of 212 g (95% confidence interval (CI): -395 to -29 g) was found for close proximity to a source, and was largest for female births (-251 g (95% CI: -487 to -15 g)). No statistically significant increased risks for any clinical birth outcomes with residential proximity of 50 m or less were observed. Living close (50 m or less) to a residential ELF-EMF source during pregnancy is associated with suboptimal growth in utero, with stronger effects in female than in males. However, only a few pregnant women live this close to high voltage cables, overhead power lines, substations or towers, likely limiting its public health impact. Bioelectromagnetics. © 2014 Wiley Periodicals, Inc.
Article
A major limitation for increasing litter size in swine is embryonic loss that occurs during the 2nd to 3rd wk of gestation. High ovulation rates of modern sows have more than supplied the potential number of embryos necessary to improve litter size. The current challenge is determining how early conceptus development affects the ability to maintain the viability through the remaining 90 d of gestation to maximize farrowing house production. To achieve this, it is neces- sary to identify and understand the possible causes of embryonic death. Because fertilization rates are gener- ally high in swine, early embryonic loss during the first 20 d of gestation is considered to critically effect poten- tial litter size. There are three periods during which early embryonic loss can occur: 1) pre-elongation devel- opment, 2) trophoblastic elongation, and 3) placental attachment. The first two periods are related to time of fertilization and subsequent developmental rate for each individual embryo within the litter. Asynchrony in embryonic development relative to uterine develop-
Article
The increasing focus on the pig as a biomedical model calls for studies which investigate morphological and molecular mechanisms during initial embryonic development in this species. In the pig, the paternal genome is actively demethylated in the zygote, whereas the maternal genome remains methylated. The major genome activation occurs at the four-cell stage, when prominent ribosome-synthesizing nucleoli develop in the blastomeres, allowing for trophectoderm and inner cell mass (ICM) differentiation. Unlike in mice, the pluripotency gene OCT4 is initially expressed in both compartments. The ICM differentiates into epiblast and hypoblast approximately at the time of hatching from the zona pellucida, and subsequently the loss of the Rauber's layer results in an uncovered epiblast establishing the embryonic disc again in contrast to mice. This particular and protracted ICM/epiblast biology may contribute to the lack of success in culturing porcine embryonic stem cells. The embryonic disc subsequently becomes polarized by a posterior thickening, which includes ingression of the first extra-embryonic mesoderm. Thereafter, the primitive streak forms and gastrulation results in formation of the somatic germ layers and germline, i.e. the primordial germ cells. The latter remain pluripotent for a period and may be isolated and cultured as embryonic germ cells in vitro.
Article
Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.
Article
Modern society continuously exposes the population to electromagnetic radiation, the effects of which on human health, in particular reproduction, are still unknown. The aim of this research was to assess the effect of acute (1h) exposure of boar spermatozoa to a 50 Hz extremely low frequency electromagnetic field (ELF-EMF) on early fertility outcome. The effect of intensities ranging from 0 to 2 mT on morpho-functional integrity of capacitated spermatozoa was examined in vitro. The oviducts containing or without spermatozoa were then exposed to the minimum in vivo, TD(50,) and maximum intensities determined in vitro, 4h before ovulation. The effects of ELF-EMF on spermatozoa in terms of early embryo development were evaluated after 12h and 6 days. It was found that in vitro ELF-EMF > 0.5 mT induced a progressive acrosome damage, thus compromising the ability of spermatozoa to undergo acrosomal reaction after zona pellucida stimulation and reducing the in vitro fertilization outcome. These effects became evident at 0.75 mT and reached the plateau at 1 mT. Under in vivo conditions, the ELF-EMF intensity of 1 mT was able to compromise sperm function, significantly reducing the fertilization rate. In addition, the exposure of oviducts to fields > or = 0.75 mT in the absence of spermatozoa was able to negatively affect early embryo development. In fact, it was found to cause a slowdown in the embryo cleavage. In conclusion, it was demonstrated how and at which intensities ELF-EMF negatively affect early fertility outcome in a highly predictive animal model.
Article
Porcine (Sus scrofa domestica) uterine slices harvested during both early pregnancy and luteolysis produce steroid hormones. The aim of the present study was to determine (1) which porcine separated uterine cells secrete androgens: androstenedione (A(4)) and testosterone (T), and estradiol-17beta (E(2)) in culture; (2) if the production of A(4), T and E(2) in the uterine cells is regulated by P4 and OT; (3) if uterine tissues expressed cytochrome P450arom gene (CYP19). Uteri were collected on Days 14 to 16 of early pregnancy and the estrous cycle. Enzymatically separated epithelial cells, stromal cells, and myocytes were cultured in vitro for 2, 6, and 12h with control medium, progesterone (P(4); 10(-5) M), oxytocin (OT; 10(-7) M), and both hormones (P(4)+OT). The studied cells secreted A(4), T, and E(2) in vitro. Progesterone served as a substrate for steroid synthesis in the uterine cells. Isolated uterine cells, cultured separately, contributed in equal portion to the basal production of androgens (A(4) and T) during both early pregnancy and luteolysis. In pregnant pigs, the epithelial and stromal cells were rich sources of E(2) compared with myocytes. Myocytes produced E(2) mainly during luteolysis. Pregnant porcine endometrium and myometrium expressed the gene CYP19, which encodes for P450 aromatase, a steroidogenic enzyme. The results indicate an active steroidogenic pathway in porcine uterine cells. The epithelial cells, stromal cells, and myocytes participate in steroid production as an alternative source for their action in pigs.
Article
Currently, a lack of consensus exists on how best to perform and interpret quantitative real-time PCR (qPCR) experiments. The problem is exacerbated by a lack of sufficient experimental detail in many publications, which impedes a reader's ability to evaluate critically the quality of the results presented or to repeat the experiments. The Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines target the reliability of results to help ensure the integrity of the scientific literature, promote consistency between laboratories, and increase experimental transparency. MIQE is a set of guidelines that describe the minimum information necessary for evaluating qPCR experiments. Included is a checklist to accompany the initial submission of a manuscript to the publisher. By providing all relevant experimental conditions and assay characteristics, reviewers can assess the validity of the protocols used. Full disclosure of all reagents, sequences, and analysis methods is necessary to enable other investigators to reproduce results. MIQE details should be published either in abbreviated form or as an online supplement. Following these guidelines will encourage better experimental practice, allowing more reliable and unequivocal interpretation of qPCR results.
Article
Unlabelled: Previously, we found that in addition to embryos, the uterine tissues may be a source of estradiol-17beta (E(2)) during early pregnancy in the pig. The aim of the present study was to determine whether porcine endometrium and myometrium secrete androgens - androstenedione (A(4)), testosterone (T) and estrone (E(1)) during early pregnancy and luteolysis (Days 14-16) in pigs. Individual endometrial and myometrial slices (200 mg) were first pre-incubated (24 h) and then incubated (6 h, 37 degrees C in an atmosphere of 95% O(2) and 5% CO(2)) in the presence or absence of progesterone (P(4); 10(-5) M), oxytocin (OT; 10(-7) M) or OT plus P(4). Basal endometrial and myometrial secretion of A(4) and T did not differ between pregnant and cyclic gilts. Endometrial secretion of E(1) was higher in pregnant than cyclic gilts (p<0.05) while myometrial secretion of E(1) did not differ between the two groups of the examined pigs (p>0.05). Progesterone significantly increased A(4) and T secretion (p<0.001) by uterine tissues regardless of the reproductive status. In the presence of P(4), endometrial and myometrial secretion of E(1) was increased only during luteolysis (p<0.001). In both tissues, OT did not affect the examined steroid secretion and did not change the effect of P(4). In conclusion: 1) porcine endometrium and myometrium was found to produce A(4), T and E(1) in vitro; 2) basal endometrial and myometrial production of A(4) and T did not differ between the examined reproductive periods; 3) the endometrium released more E(1) during early pregnancy than luteolysis; 4) in the presence of substrate (P(4)), uterine tissues increased secretion of A(4) and T during early pregnancy and luteolysis; and 5) P(4) increased uterine production of E(1) only during luteolysis. These data demonstrated the presence of the active steroid pathway in porcine endometrium and myometrium which may serve as an alternative source of androgens and estrogens in pigs.
Article
To elucidate the morphology of the initial stages of epitheliochorial placentation in the pig, material from 10 sows of the Danish Landrace and from one Göttinger minipig gilt from day 13 to day 26 of gestation was processed for scanning and transmission electron microscopy. The observed foetomaternal interaction from day 19 1/2 minipig placenta corresponded well to the observations on the Danish Landrace placenta. From the results and the discussion it was concluded that the following structures were implicated in the initial phases of placentation in the pig: Protruding epithelial proliferations of the uterine epithelium enclosed by chorionic caps serving to immobilize the blastocyst (days 13 and 14). A thick glycocalyx on the maternal and a thin one on the foetal epithelium before contact. Close apposition between the apical plasma membranes from trophoblastic and uterine epithelium (day 14). Development of interdigitating microvilli (days 15-16). Formation of apical domes on the uterine epithelium closely related to the trophoblast provided with long cytoplasmic extensions into a luminal space between the apical domes, apparently representing a transition from histiotropic to haemotrophic nutrition (days 15-20). Placentation, development of interdigitating microvilli between foetal and maternal epithelium, was extended but not terminated in the peripheral zone at day 26.
Article
Pregnancy recognition in pigs occurs between Days 11 and 12 when blastocysts undergo transformation from the spherical to filainentous form. This study evaluated the relationship between blastocyst development and total calcium (Ca), estrone (E, ), estradiol (E2), estriol (E3), E1 sulfate (E1S), E2S, E3S, prostaglandin F (PGF), PGE2, protein (Pr) and acid phosphatase (AP) activity in uterine flushings obtained from pregnant gilts between Days 10 and 14. Data from pregnant gilts were compared to those obtained from uterine flushings collected between Days 10 and 14 of the estrous cycle. Surface and ultrastructural changes in the endometrium associated with blastocyst development were evaluated by scanning (SEM) and transmission (TEM) electron microscopy. Pregnant uterine flushings were analyzed relative to average size of blastocysts recovered: 5 mm spherical, 5-8 mm spherical, 9-50 mm tubular, and >50 mm filamentous Day 12 and Day 14. Nonpregnant gilt uterine flushings were analyzed by Day of the estrous cycle (10.5, 11, 11.5, 12 and 14). Total E2 content increased almost 4-fold in pregnant uterine flushings containing tubular blastocysts (2.3 ng) as compared with flushings with spherical blastocysts (0.6 ng) and continued to increase as the blastocysts became filamentous (4.4 ng) but had declined by Day 14 (0.4 ng). The pattern of change for total recoverable E, and E3 was similar to that for E2 and the highest values were obtained in uterine flushings with filamentous blastocysts. A concomitant increase in E, S and E2 S content also was detected in flushings with tubular and Day 12 filamentous blastocysts. Total Ca, Pr, AP, PGF, and PGE2 content increased in association with increased E2 in flushings. The increase in Pr, AP, PGF and PGE2 content in pregnant flushings continued to Day 14. However, Ca content had declined by Day 14 (0.1 mg) after a transient increase to 1.5 mg in flushings that contained tubular blastocysts (Days 11 and 12). Comparable changes in estrogens, proteins, Ca, PGF and PGE2 content in nonpregnant uterine flushings collected between Days 10.5 and 14 were not detected. Electrophoresis of protein in pregnant uterine flushings indicated that the appearance of three basic uterine proteins (Mr 32K to 60K) were associated with the increase in estrogen. These proteins were detected in flushings with tubular and filamentous blastocysts (Day 12), but were not found until Day 14 in nonpregnant gilts. A synchronized release of secretory vesicles from the glandular epithelium was observed by TEM which indicated a close association between formation of tubular blastocysts, onset of blastocyst estrogen production and increased protein in uterine flushings. Although secretion was detected in nonpregnant glandular epithelium, no synchronized release was observed. Results suggest that estrogen production by tubular and early filamentous blastocysts (Day 11.5-12.0) stimulates secretion of protein from the endometrium which may be mediated through an effect of free Ca on the uterine glandular epithelium. Increases in PGF and PGE2 were associated closely with estrogen production and blastocyst elongation.
Article
The formation of estrogens in mammals via aromatase involves the relatively unique capacity to form an aromatic ring de novo in contrast to most other aromatic substances (essential amino acids) which are obtained only in the diet. The reaction is the only example of a cytochrome P450 system which resides in both the mitochondrial and microsomal fractions of the cell. It occurs widely throughout the body in diverse tissues and functions via both de novo synthesis and transformation of prehormones (androstenedione and testosterone). It is found widely in animal species in both the brain and gonads even in phylogenetically primitive species. Placental aromatase appears to be associated with the evolution of viviparity and an extended gestational period in utero. Follicular aromatase which is dependent upon follicle-stimulating hormone stimulation appears to be essential for oogenesis, ovulation, and normal luteal functions while central nervous system aromatase serves to determine sexual behavior and the neurohormonal link to the hypothalamus and pituitary for ovarian cyclicity. While estrogens are the key to pituitary, breast, and endometrial growth and development, this hormone is one of the few examples of an endogenous steroid that has been implicated as a carcinogen or a stimulant for carcinogenesis.
Article
It has been hypothesized that conceptus estrogens influence endometrial protein secretion during pregnancy in swine. To test this hypothesis, the effect of estrone and estradiol treatment from d 30 to 60 of pregnancy or pseudopregnancy on endometrial protein secretion was investigated. Pregnant (P; n = 16) and pseudopregnant (PP) gilts (n = 18) received either sham treatment or estrone or estradiol implants (5 mg/d release rate; 60 d release) on d 30 of P or PP. Blood samples were collected on d 30, 40, 50, and 60 to measure estrone and estradiol. On d 60, gilts were hysterectomized. For P gilts, endometrium in apposition to one placenta from each uterine horn was collected. For PP gilts, each uterine horn was flushed with 40 mL of leucine-deficient minimal essential medium (MEM), and endometrial tissue was collected from each horn. Endometrial tissues were incubated in MEM in the presence of 50 microCi of [3H]leucine to examine protein secretion. Estrone and estradiol treatments increased both plasma and endometrial concentrations of estrone (P < .01 except endometrium for P gilts) and estradiol (P < .01, respectively). Endometrium from P gilts secreted more nondialyzable macromolecules (NDM), acid phosphatase activity (AP, a measure of uteroferrin), and retinol-binding protein (RBP) in culture than did endometrium from PP gilts. Estrone treatment increased (P < .01) endometrial NDM from P gilts but not that from PP gilts; estradiol had no effect. Both estrone and estradiol increased (P = .069) endometrial secretion of AP of PP but not of P gilts. Endometrial secretion of RBP was not affected by either estrone or estradiol treatment. Neither estrone nor estradiol affected total protein or AP and estrone treatment decreased (P < .05) RBP in uterine flushings from PP gilts. These data indicate that endometrium from P pigs secretes more protein than endometrium from PP pigs but neither estrone nor estradiol completely mimics the effect of pregnancy.
Article
While the ovaries are the principal source of systemic estrogen in the premenopausal nonpregnant woman, other sites of estrogen biosynthesis are present throughout the body and these become the major sources of estrogen beyond menopause. These extragonadal sources of estrogen are small, but may play an important, though hitherto largely unrecognized, physiological and pathophysiological role. Aromatase activity in extragonadal sites contributes to this source of estrogen and may contribute to breast tumor development and/or growth. Selective aromatase modulators (SAMs) may have a role to play in the treatment of estrogen-dependent diseases, such as breast cancer.
Article
Groups of mated female Sprague-Dawley rats were simultaneously exposed to 0 (sham exposed), 7, 70, or 350 microT (rms) circularly polarized 50 Hz magnetic fields (MF) for 22 h/day on gestational day 8-15, the period of rat fetal organogenesis (organogenesis study) or from day 0 to day 7 of gestation, the rat preimplantation period (preimplantation study). Developmental toxicity was assessed on gestational day 20. Identical experiments were repeated to confirm reproducibility of both studies. In both studies, statistically significant differences between exposed and sham exposed animals were observed in several measured parameters; however, these differences only appeared in one, but not both replicate experiments and generally at only an isolated exposure level. Because these differences were not reproducible and did not show a dose response relationship, they were not considered related to MF exposure. In the organogenesis study, lower kidney weights of dams were seen at 70 and 350 microT in Experiment 1. Lower dam liver weights and lower mean body weights of viable female and male fetuses were seen at 70 microT in Experiment 2. Otherwise, there were no differences in these parameters or in group means for fetal loss after implantation, number of viable fetuses, fetal body weight and sex ratio, incidences of external, visceral, and skeletal abnormalities or variations, or tissue abnormalities after histopathological examination. In the preimplantation study, dam health and indices for reproduction and embryo-fetal development, including pre or postimplantation loss, number and body weight of live fetuses, and sex ratio, external, skeletal abnormalities and variations, and skeletal ossification did not differ. Dam inorganic phosphorous concentration at 350 microT was elevated in one experiment and depressed in another. In one experiment, visceral abnormalities, primarily thymic remnant in neck and accessory liver lobe, were increased in the 7 microT group. Based on these results from two studies, we conclude that circularly polarized 50 Hz MF exposure of up to 350 microT during the fetal organogenesis or during the preimplantation period does not affect reproduction and embryo-fetal development in Sprague-Dawley rats.
Article
In 1977 Bazer and Thatcher proposed that maternal recognition of pregnancy in the pig involves the secretion of PGF(2alpha) towards the uterine lumen (exocrine) rather than towards the uterine venous drainage (endocrine) as occurs in the non-pregnant pig during the mid to late stages of the estrous cycle. The retrograde transfer of PGF(2alpha) from the venous blood and uterine lymph into the uterus and the ability of the uterine vein and artery wall to accumulate PGF(2alpha) could constitute a part of putative mechanism of corpus luteum protection during early pregnancy. A luteotropic/anti-luteolytic effect of PGE(2) in the pig also has been frequently demonstrated and it seems that the most effective agent in changing PGE(2):PGF(2alpha) secretion is estradiol. The role for oxytocin during luteolysis and early pregnancy is controversial. It appears, however, that the main function of this hormone is autocrine and/or paracrine stimulation of PGF(2alpha) secretion. Pig trophoblastic interferons, unlike those of ruminants, do not themselves exert an anti-luteolytic effect in pigs. It is likely, that cytokines and angiogenic growth factors are involved in the initiation of luteolysis and/or maintenance of corpora lutea (CL).A discovery of functional LH receptors in porcine endometrium opened a new possibility for this hormone in luteolysis and perhaps in recognition of pregnancy in pigs. The endogenous LH pulses can provoke prostaglandin secretion from endometrium in pigs. On the other hand prolongation of up-regulation of LH receptors in endometrium of early pregnant gilts can additionally increase angiogenic factor production before the process of implantation is completed. Finally new integrated concepts of luteolysis and inhibition of luteolysis in pigs based on selectively reviewed information are presented.
Article
Progesterone is unequivocally required for maternal support of conceptus (embryo/fetus and associated extraembryonic membranes) survival and development. In cyclic sheep, progesterone is paradoxically involved in suppressing and then initiating development of the endometrial luteolytic mechanism. In cyclic and pregnant sheep, progesterone negatively autoregulates progesterone receptor (PR) gene expression in the endometrial luminal (LE) and superficial glandular epithelium (GE). In cyclic sheep, PR loss is closely followed by increases in epithelial estrogen receptor (ERalpha) and then oxytocin receptor (OTR), allowing oxytocin to induce uterine release of luteolytic prostaglandin F2alpha pulses. In pregnant sheep, the conceptus produces interferon tau (IFNtau) that acts on the endometrium to inhibit transcription of the ERalpha gene and thus development of the endometrial luteolytic mechanism. After Day 13 of pregnancy, the endometrial epithelia do not express the PR, whereas the stroma and myometrium remain PR positive. The absence of PR in the endometrial GE is required for onset of differentiated function of the glands during pregnancy. The sequential, overlapping actions of progesterone, IFNtau, placental lactogen (PL), and growth hormone (GH) comprise a hormonal servomechanism that regulates endometrial gland morphogenesis and terminal differentiated function during gestation. In pigs, estrogen, the pregnancy-recognition signal, increases fibroblast growth factor 7 (FGF-7) expression in the endometrial LE that, in turn, stimulates proliferation and differentiated functions of the trophectoderm, which expresses the receptor for FGF-7. Strategic manipulation of these physiological mechanisms may offer therapeutic schemes to improve uterine capacity, conceptus survival, and reproductive health of domestic animals and humans.
Article
The objective of this study was to monitor and compare follicle populations and follicular development in pregnant and nonpregnant sows from Day 3 to Day 20 after breeding. Twenty-four sows were paired within parity on the day of artificial insemination and were randomly allocated within pair for insemination with either killed (n=12) or live spermatozoa (n=12). All the sows were artificially inseminated with the pooled ejaculate of the same boar. From Day 3 through Day 20 post estrus, ovarian follicles were scanned daily by ultrasonography. Ultrasound images were recorded on videotape and were retrospectively analyzed. Follicles were mapped to identify the existence of follicular waves. The follicles were then classified as small (< 3 mm), medium (3-5 mm), or large (> or =5 mm). Pregnancy diagnosis was performed on Day 21 by ultrasonography. Pregnant sows maintained a constant proportion of the follicle population in the small, medium and large follicle categories. However, in the nonpregnant sows, the proportion of follicles in the various size categories remained constant until Day 15. Thereafter, the proportion of small follicles decreased (P < 0.05) from Day 15 to 20, and the proportions of medium and large follicles increased (P < 0.05). The predictability of pregnancy status on Day 20 based on follicle populations in any of the 3 follicle categories was low. Moreover, there was no evidence of follicular waves during the estrous cycle or early pregnancy. In conclusion, the proportion of small follicles decreased while medium and large follicle increased from Day 15 through Day 20 of the estrous cycle, but not during a similar stage of pregnancy. This latter finding concurs with follicle recruitment from the pool of small follicles for ovulation following PGF2alpha secretion to induce luteolysis, which reduces progesterone concentrations and thereby allows for the stimulation of the pool of small follicles by gonadotropins.
Article
Past studies of the source of estrogens secreted during maternal recognition of pregnancy in pigs have focused on embryonic rather than uterine origin of these steroids. The present study documents: (1) the expression of the gene CYP 17, encoding cytochrome P450 17alpha-hydroxylase/C(17-20) lyase and (2) the synthesis and secretion of estradiol-17 beta (E(2)) in endometrial and myometrial tissues in gilts. The expression of CYP 17 gene was shown in porcine endometrium and myometrium. Basal endometrial secretion of E(2) was higher in pregnant gilts than in cyclic gilts (days 14-16). The myometrium secreted more E(2) during the expected time of luteolysis compared to early pregnancy. Basal secretion of E(2) during pregnancy was higher from the endometrium than from the myometrium. Conversely, during luteolysis E(2) secretion was higher from the myometrium and lower from the endometrium. In pregnant and cyclic gilts (days 14-16), progesterone (P(4), 10(-5)M) in vitro significantly increased E(2) secretion regardless of reproductive status. Oxytocin (OT, 10(-7)M) had no influence on E(2) secretion and did not change the stimulatory effect of P(4) in both tissues examined. In conclusions: (1) the CYP 17 gene transcript is present in porcine endometrium and myometrium; (2) porcine endometrium and myometrium release E(2) in vitro; (3) the endometrium releases more E(2) than the myometrium during early pregnancy; (4) the myometrium releases E(2) mainly during luteolysis; (5) the endometrium and myometrium can increase E(2) release in vitro if substrate (P(4)) is provided during early pregnancy and luteolysis. These data suggest active estrogen production by the myometrium and endometrium as an alternative source for this signal for recognition of pregnancy in the pig.
Radioimmunoassay of steroid hormones in biological fluids
  • Ciereszko