Prostanoid receptors EP2, EP4, and FP are regulated by estradiol in bovine oviductal smooth muscle

Prostaglandin E2 receptor Ptger4b regulates female-specific peptidergic neurons and female sexual receptivity in medaka

In vertebrates, female receptivity to male courtship is highly dependent on ovarian secretion of estrogens and prostaglandins. We recently identified female-specific neurons in the medaka (Oryzias latipes) preoptic area that express Npba, a neuropeptide mediating female sexual receptivity, in response to ovarian estrogens. Here we show by transcriptomic analysis that these neurons express a multitude of neuropeptides, in addition to Npba, in an ovarian-dependent manner, and we thus termed them female-specific, sex steroid-responsive peptidergic (FeSP) neurons. Our results further revealed that FeSP neurons express a prostaglandin E₂ receptor gene, ptger4b, in an ovarian estrogen-dependent manner. Behavioral and physiological examination of ptger4b-deficient female medaka found that they exhibit increased sexual receptivity while retaining normal ovarian function and that their FeSP neurons have reduced firing activity and impaired neuropeptide release. Collectively, this work provides evidence that prostaglandin E₂/Ptger4b signaling mediates the estrogenic regulation of FeSP neuron activity and female sexual receptivity.

Prostaglandin E₂ signaling mediates the estrogenic regulation of peptidergic neuronal activity and female receptivity via the ptger4b gene pathway in Japanese rice fish.

Do commonly used herbicides (atrazine and glyphosate) have the potential to impair the contractions, prostaglandin releasing and conducting of oxytocin signal at the bovine cervix in vitro?

Glyphosate (Gly) and atrazine (Atr) are among the most commonly used herbicides in global agriculture. It was previously shown that both Atr and Gly impair the ovarian and uterine secretion of regulators of myometrial motility (oxytocin (OT) or prostaglandins (PGs)) in cows, and Atr can also decrease the force of contractions in strips from the uterine horn. Hence, the aim of this study was to compare the effects of Atr and Gly on the motor and secretory function of the bovine cervix in vitro as well as receptivity and signal transduction in cervical cell cultures. Cervical strips or cells obtained from cows before ovulation were treated with environmental doses of Atr or Gly (0.1-10 ng/ml) since these herbicides exerted no cytotoxic effect at a dose of 100 ng/ml. Only Atr increased the force of cervical contractions, while both Atr and Gly decreased the secretion of prostaglandins (PGs) without disturbing their synthesis. Moreover, Atr decreased the mRNA expression and protein level of oxytocin receptor (OTR), while Gly increased OTR protein levels. Both Atr and Gly decreased the contents of gap junction proteins (GAPs), Atr decreased the contents of second messengers (diacylglycerol - DAG, inositol-tris-phosphate - IP3), and Gly decreased the level of myosin light chain kinase (MLCK) but increased DAG levels. Atr directly enhanced the cervical strips contractions. Both herbicides disturbed cellular signalling and inhibited PGs secretion. It suggest that Atr and Gly have the potential to impair the activity of cervical cells in vitro, which might be followed by failure of maintenance with gestation.

The role of the oviduct and extracellular vesicles during early embryo development in bovine

The oviduct is an important reproductive structure that connects the ovary to the uterus and takes place to important events such as oocyte final maturation, fertilization and early embryonic development. Thus, gametes and embryo can be directly influenced by the oviductal microenvironment composed by epithelial cells such secretory and ciliated cells and oviductal fluid. The oviduct composition is anatomically dynamic and is under ovarian hormones control. The oviductal fluid provides protection, nourishment and transport to gametes and embryo and allows interaction to oviductal epithelial cells. All these functions together allows the oviduct to provides the ideal environment to the early reproductive events. Extracellular vesicles (EVs) are biological nanoparticles that mediates cell communication and are present at oviductal fluid and plays an important role in gametes/embryo - oviductal cells communication. This review will present the ability of the oviducts based on its dynamic and systemic changes during reproductive events, as well as the contribution of EVs in this process.

Administration of PGF2α at the moment of timed-AI using sex-sorted or conventional semen in suckled nelore cows with different intensity of estrus behavior

The aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2α at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2α treatment at AI in cows inseminated with conventional or sex-sorted semen, with the absence or expression of estrus. In experiment 1, a total of 701 suckled, multiparous Nelore cows from two commercial beef farms were submitted to the same protocol. All cows received a 12.5 mg (IM) injection of dinoprost tromethamine (Dinoprost; Lutalyse®; PGF treatment) at days 7 and 9 of a timed-AI protocol. Following P4 device removal (day 11; D11), AI was performed 48 h later with conventional or sex-sorted semen from two different sires. At AI, cows received an additional dose of 12.5 mg (IM) of Dinoprost (PGF treatment) or 2.5 mL (IM) of sterile saline (Control). Estrus behavior was determined at D11 by activation of an estrus detection device (Estrotect®). The overall PR was 32.8% (n = 348) at Farm 1 and 42.3% (n = 353) at Farm 2 (P = 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P = 0.02), estrus behavior (P = 0.01), and type of semen (P < 0.001) were factors affecting PR. Conventional semen had a 2.73x greater chance of successful pregnancy than sex-sorted semen. Cows displaying estrus had a 2.5x greater chance of successful pregnancy than cows that did not display estrus. No treatment effect (P = 0.67) was detected in cows receiving conventional or sex-sorted semen. However, there was a tendency (P = 0.08) for an interaction between treatment (PGF or control) and estrus behavior (estrus or no estrus). PGF2α at the time of AI tended to increase PR of cows that did not display estrus (P < 0.10). In experiment 2, 29 suckled, multiparous Nelore cows were compared using B-mode and Doppler ultrasongraphy to assess the ovulatory characteristics of cows receiving the 12.5 mg (IM) injection of Dinoprost (PGF treatment) or saline solution (control) at D11. No significant effects of PGF2α treatment at D11 were observed in follicular characteristics and/or ovulation performance. It was concluded that fertility of sex-sorted semen was lower than conventional semen, regardless of the PGF2α treatment. The 12.5 mg treatment of Dinoprost at AI did not accelerate the occurrence of ovulation; however, it was interesting to note that PGF2α treatment at timed-AI appeared to increase the fertility of cows that did not display estrus, independent of semen type.

Effect of cyclo‑oxygenase inhibition on embryonic microglia and the sexual differentiation of the brain and behavior of Japanese quail (Coturnix japonica)

Enduring sex differences in the brain are established during a developmental process known as brain sexual differentiation and are mainly driven by estrogens during a critical period. In rodents, the masculinization of the preoptic area by estrogens derived from the central aromatization of testosterone depends in part on the interaction between microglia and prostaglandin E₂ (PGE₂), a pro-inflammatory hormone of the prostanoid subclass. In contrast, in birds, estrogens produced by females induce a demasculinization, but whether an interaction with the neuro-immune system is involved in this process is unknown. This study addressed this question by testing the effects of blockade of cyclo‑oxygenases (COX), the rate-limiting enzymes for prostanoid synthesis, on embryonic microglia and the sexual differentiation of brain and behavior using the Japanese quail as an animal model. The results show that COX inhibition does not affect the behavior of females, but impairs male sexual behavior and suppresses the sex difference in microglial profiles at embryonic day 12 (E12) in the medial preoptic nucleus by increasing the number of microglia in males only. However, neither prostanoid concentrations nor PGE₂ receptors differed between sexes in the hypothalamus and preoptic area (HPOA) during development. Overall, these results uncovered a potential role of prostanoids in the demasculinization of Japanese quail. Moreover, the parallel effect of COX inhibition on behavior and microglia suggests an interaction between prostanoids and microglia in brain demasculinization, thus fueling the hypothesis of a conserved role of the neuroimmune system in the organization of the brain by estrogens.

Prostaglandin-Endoperoxide Synthase 2 (PTGS2) in the Oviduct: Roles in Fertilization and Early Embryo Development

The mammalian oviduct is a dynamic organ where important events such as final maturation of oocytes, transport of gametes, sperm capacitation, fertilization, embryo development, and transport take place. Prostaglandin-endoperoxide synthase 2 (PTGS2), also known as cyclooxygenase 2 (COX-2), is the rate-limiting enzyme in the production of prostaglandins (PGs) and plays an essential role during early pregnancy, including ovulation, fertilization, implantation, and decidualization. Even though the maternal-embryo communication originates in the oviduct, not many studies have systemically investigated PTGS2 signaling during early development. Most of the studies investigating implantation and decidualization processes in Ptgs2-/- mice employed embryo transfer into the uterus, thereby bypassing the mammalian oviduct. Consequently, an understanding of the mechanistic action as well as the regulation of PTGS2 and derived PGs in oviductal functions is far from complete. In this review, we aim to focus on the importance of PTGS2 and associated PGs signaling in the oviduct particularly in humans, farm animals, and laboratory rodents to provide a broad perspective to guide further research in this field. Specifically, we review the role of PTGS2-derived PGs in fertilization, embryo development, and transport. We focus on the actions of ovarian steroid hormones on PTGS2 regulation in the oviduct. Understanding of cellular PTGS2 function during early embryo development and transport in the oviduct will be an important step toward a better understanding of reproduction and may have potential implication in the assisted reproductive technology.

Dysregulation of prostaglandine E2 and BDNF signaling mediated by estrogenic dysfunction induces primary hippocampal neuronal cell death after single and repeated paraquat treatment

Paraquat (PQ) produces hippocampal neuronal cell death and cognitive dysfunctions after unique and continued exposure, but the mechanisms are not understood. Primary hippocampal wildtype or βAPP-Tau silenced cells were co-treated with PQ with or without E2, N-acetylcysteine (NAC), NS-398 (cyclooxygenase-2 inhibitor), MF63 (PGES-1 inhibitor) and/or recombinant brain-derived neurotrophic factor (BDNF) during one- and fourteen-days to studied PQ effect on prostaglandin E2 (PGE2) and BDNF signaling and their involvement in hyperphosphorylated Tau (pTau) and amyloid-beta (Aβ) protein formation, and oxidative stress generation, that lead to neuronal cell loss through estrogenic disruption, as a possible mechanism of cognitive dysfunctions produced by PQ. Our results indicate that PQ overexpressed cyclooxygenase-2 that leads to an increase of PGE2 and alters the expression of EP1-3 receptor subtypes. PQ induced also a decrease of proBDNF and mature BDNF levels and altered P75^NTR and tropomyosin receptor kinase B (TrkB) expression. PQ induced PGE2 and BDNF signaling dysfunction, mediated through estrogenic disruption, leading to Aβ and pTau proteins synthesis, oxidative stress generation and finally to cell death. Our research provides relevant information to explain PQ hippocampal neurotoxic effects, indicating a probable explanation of the cognitive dysfunction observed and suggests new therapeutic strategies to protect against PQ toxic effects.

Glyphosate affects the secretion of regulators of uterine contractions in cows while it does not directly impair the motoric function of myometrium in vitro

The effects of pure glyphosate and its most popular product (brand name: Roundup) on the secretion of hormones involved in the regulation of myometrial contractions as well as their direct effects on myometrial contractions were examined. Myometrial strips as well as uterine and ovarian cells were taken from cows during the oestrous cycle and they were treated with both compounds at concentrations from their environmental range. Glyphosate stimulated the secretion of oestradiol from granulosa cells while both herbicides increased and decreased oxytocin (OT) and progesterone secretion from luteal cells respectively. However only Roundup stimulated mRNA expression of the precursor of OT. Both compounds decreased the secretion of prostaglandins from endometrial cells while they exerted no effect on the basal and OT-stimulated force of myometrial contractions. The studied herbicides did not directly impair the motoric function of the myometrium. However our data indicate the potential of these compounds to disturb the secretory functions of the ovaries and uterus which can lead to the deregulation of uterine contractions and to the impairment of fertilisation or to difficulties in the maintenance of gestation.

Chlorinated insecticides (toxaphene and endrin) affect oxytocin, testosterone, oestradiol and prostaglandin secretion from ovarian and uterine cells as well as myometrial contractions in cow in vitro

We examined the direct effects of toxaphene and endrin, chlorinated insecticides that are widespread in the environment, on myometrial contractions and on the secretion of hormones involved in regulating these contractions. Granulosa, luteal, endometrial and myometrial cells, and myometrial strips from non-pregnant cows were incubated with both insecticides at environmentally relevant doses. Toxaphene inhibited and endrin stimulated the secretion of testosterone and oestradiol from granulosa cells. Toxaphene also inhibited and endrin stimulated the expression of the mRNA encoding the precursor of oxytocin (OT), as well OT secretion in luteal cell cultures. Moreover, endrin increased OT secretion from granulosa cells. Neither insecticide exerted an effect on progesterone secretion from luteal cells. Only toxaphene decreased the secretion of prostaglandins (PGF2 and PGE2) from endometrial cells. Meanwhile, only endrin decreased basal myometrial contractions, which was accompanied by inhibition of PGF2 secretion from the myometrium. Both endrin and toxaphene also decreased the force of the OT-stimulated myometrial contractions, whereas only toxaphene inhibited the stimulatory effect of OT on the force of myometrial contractions. In contrast to endrin, toxaphene decreased synthesis and secretion of one of the primary stimulators of myometrial contractions (OT) and indirectly inhibited OT signal reception in the myometrium by reducing E2 secretion. Both insecticides decreased OT-stimulated myometrial contractions; therefore, they may inhibit further transmission of the OT signal. Moreover, endrin inhibited basal myometrial contractions, potentially resulting from reduced PGF2 secretion from the myometrium. Our data indicate the potential of these insecticides to disturb the course of the oestrous cycle or fertilisation.

Estrogen induces EGR1 to fine-tune its actions on uterine epithelium by controlling PR signaling for successful embryo implantation

The harmonized actions of ovarian E₂ and progesterone (P₄) regulate the proliferation and differentiation of uterine cells in a spatiotemporal manner. Imbalances between these hormones often lead to infertility and gynecologic diseases. Whereas numerous factors that are involved in P₄ signaling have been identified, few local factors that mediate E₂ actions in the uterus have been revealed. Here, we demonstrate that estrogen induces the transcription factor, early growth response 1 ( Egr1), to fine-tune its actions in uterine epithelial cells (ECs) that are responsible for uterine receptivity for embryo implantation. In the presence of exogenous gonadotrophins, ovulation, fertilization, and embryonic development normally occur in Egr1^-/- mice, but these animals experience the complete failure of embryo implantation with reduced artificial decidualization. Although serum levels of E₂ and P₄ were comparable between Egr1^+/+ and Egr1^-/- mice on d 4 of pregnancy, aberrantly reduced levels of progesterone receptor in Egr1^-/- uterine ECs caused enhanced E₂ activity and impaired P₄ response. Ultrastructural analyses revealed that Egr1^-/- ECs are not fully able to provide proper uterine receptivity. Uterine mRNA landscapes in Egr1^-/- mice revealed that EGR1 controls the expression of a subset of E₂-regulated genes. In addition, P₄ signaling was unable to modulate estrogen actions, including those that are involved in cell-cycle progression, in ECs that were deficient in EGR1. Furthermore, primary coculture of Egr1^-/- ECs with Egr1^+/+ stromal cells, and vice versa, supported the notion that Egr1 is required to modulate E₂ actions on ECs to prepare the uterine environment for embryo implantation. In contrast to its role in ECs, loss of Egr1 in stroma significantly reduced stromal cell proliferation. Collectively, our results demonstrate that E₂ induces EGR1 to streamline its actions for the preparation of uterine receptivity for embryo implantation in mice.-Kim, H.-R., Kim, Y. S., Yoon, J. A., Yang, S. C., Park, M., Seol, D.-W., Lyu, S. W., Jun, J. H., Lim, H. J., Lee, D. R., Song, H. Estrogen induces EGR1 to fine-tune its actions on uterine epithelium by controlling PR signaling for successful embryo implantation.

Effect of estrogen on prostaglandin synthetase in bovine oviduct smooth muscle

Gamete and embryo transport is an important function of the oviduct. This type of transport involves both smooth muscle contraction and epithelial cell secretions, and the former is mediated by prostaglandins (PGs) and their receptors. Our objective was to study the regulation of prostaglandin synthetase (prostaglandin-endoperoxide synthase-1 (PTGS1), prostaglandin-endoperoxide synthase-2 (PTGS2), mPGES-1, mPGES-2, cPGES, and PGFS) by estradiol (E₂) in bovine oviduct smooth muscle. Prostaglandin synthetase mRNA and protein expression were investigated using real-time RT-PCR and Western blot analyses, respectively. Prostaglandin synthetase mRNA and protein expression were increased in oviductal smooth muscle tissue after treatment with different concentrations of estradiol for various time periods. The results indicated that there was no increase in expression observed after treatment with fulvestrant, a selective antagonist of the E₂ receptor, indicating that E₂ interacts with specific E₂ nuclear receptors to upregulate PTGS1, PTGS2, mPGES-1, and PGFS expression. In conclusion, E₂ increases PTGS1, mPGES-1, and PGFS mRNA and protein expression in bovine oviductal smooth muscle when added for different periods of time and at different concentrations. Additionally, E₂ is transported intracellularly and interacts with specific E₂ nuclear receptors to increase PTGS1, PTGS2, mPGES-1 and PGFS expression.

The inhibition of myometrial contractions by chlorinated herbicides (atrazine and linuron), and their disruptive effect on the secretory functions of uterine and ovarian cells in cow, in vitro

The effect of atrazine and linuron, the popular and widely used chlorinated herbicides, on both myometrial contractions and secretory functions of bovine uterus and ovaries in vitro, was investigated. The pesticides inhibited (P<0.05) the basal and oxytocin (OT)-stimulated myometrial strips contractions, as well as the effect of OT on secretion of prostaglandins (PGs: PGF2α and PGE2) from endometrium. But only linuron inhibits the effect of OT on myometrial contractions. Neither of herbicides affected PGs secretion from myometrium and PGF2α from endometrium. Only the lowest dose of both tested compounds decreased PGE2 secretion from endometrium. The pesticides increased (P<0.05) the OT secretion from granulosa. However, only linuron stimulated (P<0.05) the OT secretion from the luteal cells, and it increased (P<0.05) the expression of mRNA for the OT precursor. Both compounds stimulated (P<0.05) the secretion of testosterone and atrazine increased (P<0.05) also the secretion of estradiol from the granulosa cells. While atrazine and linuron reduced (P<0.05) the progesterone secretion from the luteal cells. The data show that atrazine and linuron altered the secretory functions of ovarian cells and inhibited the myometrial contractions in vitro.

Oviduct: roles in fertilization and early embryo development

Animal oviducts and human Fallopian tubes are a part of the female reproductive tract that hosts fertilization and pre-implantation development of the embryo. With an increasing understanding of roles of the oviduct at the cellular and molecular levels, current research signifies the importance of the oviduct on naturally conceived fertilization and pre-implantation embryo development. This review highlights the physiological conditions within the oviduct during fertilization, environmental regulation, oviductal fluid composition and its role in protecting embryos and supplying nutrients. Finally, the review compares different aspects of naturally occurring fertilization and assisted reproductive technology (ART)-achieved fertilization and embryo development, giving insight into potential areas for improvement in this technology.

Secretory function of ovarian cells and myometrial contractions in cow are affected by chlorinated insecticides (chlordane, heptachlor, mirex) in vitro

The aim of the study was to investigate the effect of chlordane, heptachlor and mirex, on hormonal regulation of the force of myometrial contractions. Myometrial, endometrial, granulosa and luteal cells as well as strips of myometrium from non-pregnant cows were incubated with three insecticides at environmentally relevant doses (0.1, 1 or 10ng/ml). None of the insecticides affected the viability of studied cells. Chlordane stimulated, while heptachlor and mirex inhibited, secretion of testosterone and estradiol from granulosa cells as well as secretion of progesterone from luteal cells, respectively. Secretion of oxytocin (OT) from granulosa cells was increased after incubation with all studied insecticides. Only mirex stimulated OT secretion from luteal cells, while heptachlor inhibited this effect. None of them affected synthesis of OT in luteal cells and prostaglandins (PGF2 and PGE2) secretion from uterine cells, except PGE2 secretion from endometrial cells was decreased when the cells were incubated with 0.1ng/ml of chlordane. Basal and OT-stimulated myometrial contractions were increased by mirex and decreased by heptachlor. The data show that the insecticides altered secretory function of ovarian cells. Heptachlor and mirex affected also myometrial contractions in vitro, but uterine secretion of prostaglandins were not involved in the mechanism of that adverse effect of insecticides. The data indicate on potential of these insecticides to disturb fertilisation, blastocyst implantation or even the length of gestation.

The expression of prostaglandin-E2 and its receptor in the oviduct of Chinese brown frog (Rana dybowskii)

The Chinese brown frog (Rana dybowskii) has one special physiological phenomenon, which is that its oviduct expands prior to hibernation rather than in the breeding period. In this study, we investigated the immunolocalization and expression levels of prostaglandin-E2 (PGE2), cyclooxygenase (COX)-1 and COX-2, as well as one of its receptor subtypes 4 (EP4) in the oviduct of Rana dybowskii during the pre-hibernation and breeding period. PGE2, COX-1, COX-2 and EP4 have been observed in glandular and epithelial cells in the breeding period, whereas only in the epithelial cells during the pre-hibernation. Consistently, the protein levels of COX-2 and EP4 were higher in the pre-hibernation as compared to the breeding period, but the diversity of COX-1 was not obvious. In addition, oviductal PGE2 concentration was also significantly higher in the pre-hibernation. These results suggested that prostaglandin-E2 may play an important autocrine or paracrine role in oviductal cell proliferation and differentiation of Rana dybowskii during pre-hibernation.

Estrogen Receptor Alpha (ESR1)-Dependent Regulation of the Mouse Oviductal Transcriptome

Estrogen receptor-α (ESR1) is an important transcriptional regulator in the mammalian oviduct, however ESR1-dependent regulation of the transcriptome of this organ is not well defined, especially at the genomic level. The objective of this study was therefore to investigate estradiol- and ESR1-dependent regulation of the transcriptome of the oviduct using transgenic mice, both with (ESR1KO) and without (wild-type, WT) a global deletion of ESR1. Oviducts were collected from ESR1KO and WT littermates at 23 days of age, or ESR1KO and WT mice were treated with 5 IU PMSG to stimulate follicular development and the production of ovarian estradiol, and the oviducts collected 48 h later. RNA extracted from whole oviducts was hybridized to Affymetrix Genechip Mouse Genome 430–2.0 arrays (n = 3 arrays per genotype and treatment) or reverse transcribed to cDNA for analysis of the expression of selected mRNAs by real-time PCR. Following microarray analysis, a statistical two-way ANOVA and pairwise comparison (LSD test) revealed 2428 differentially expressed transcripts (DEG’s, P < 0.01). Genotype affected the expression of 2215 genes, treatment (PMSG) affected the expression of 465 genes, and genotype x treatment affected the expression of 438 genes. With the goal of determining estradiol/ESR1-regulated function, gene ontology (GO) and bioinformatic pathway analyses were performed on DEG’s in the oviducts of PMSG-treated ESR1KO versus PMSG-treated WT mice. Significantly enriched GO molecular function categories included binding and catalytic activity. Significantly enriched GO cellular component categories indicated the extracellular region. Significantly enriched GO biological process categories involved a single organism, modulation of a measurable attribute and developmental processes. Bioinformatic analysis revealed ESR1-regulation of the immune response within the oviduct as the primary canonical pathway. In summary, a transcriptomal profile of estradiol- and ESR1-regulated gene expression and related bioinformatic analysis is presented to increase our understanding of how estradiol/ESR1 affects function of the oviduct, and to identify genes that may be proven as important regulators of fertility in the future.