Preimplantation Period Of Pregnancy Research Articles

Glutathione peroxidase 1 and 2 during preimplantation period of pregnancy in mouse.

This study describes the presence of glutathione peroxidase (GPx) 1 and 2 in oocytes, preimplantation embryos, and mouse female genital organs. GPx1 and 2 are antioxidant enzymes, which play important roles in protection of cells against oxidation, which may be formed during cell physiological processes. After superovulation of female mice, oocytes and preimplantation embryos (O/PE) were isolated for immunofluorescent analysis, female genital organs were removed for immunohistochemical and Western blot analyses. Using immunofluorescence, GPx1 was detected in all OP/E, where it formed clusters near nuclei, or under the cytoplasmic membrane. GPx2 was not detected in any O/PE. Using immunohistochemistry, GPx1 was observed in corpus luteum and oocytes, and in oviductal and uterine epithelium. GPx2 was detected in corpus luteum, but not in oocytes. Oviductal and uterine epithelium was mostly negative. Using Western blot, two GPx1 bands of different molecular weights were detected in uterus. One GPx2 band was observed in all investigated organs. These results show that both enzymes may be important during preimplantation period of pregnancy in genital organs, GPx1 also in O/PE. GPx2 may play roles in embryo after the implantation, when gastrointestinal tract is formed (Fig. 10, Ref. 75).

278 Awardee Talk: Progesterone Regulates the Abundance of Mrnas and Proteins Involved in Polyamine Metabolism in the Sheep Endometrium

Abstract Agmatine and polyamines (putrescine, spermidine, and spermine), metabolites of L-arginine, are important for development of mammalian conceptuses. The objective of this study was to determine if exogenous progesterone administered during the pre-implantation period, which accelerates conceptus development, alters the expression of mRNAs and proteins involved in the metabolism of agmatine and polyamines in the sheep uterus during pregnancy. Mature Suffolk ewes were bred to fertile rams and assigned randomly to be treated with daily i.m. injections of either 1ml corn oil (CO;n=28) or 25mg progesterone in corn oil (P4;n=20) from Day 1.5 through Day 8 after breeding (Day 0). Ewes were hysterectomized on Day 9, 12, or 125 of gestation and endometrial samples were collected. The expression of candidate mRNAs was quantified using qPCR and proteins localized using immunohistochemistry. On Day 9 of pregnancy, the expression of mRNAs for AMD1 (P < 0.01), ASL (P < 0.01), and SLC12A8 (P < 0.05) was greater in endometria of P4-treated compared to CO-treated ewes. The expression for MAT2B mRNA was greater (P < 0.001) for P4-treated compared to CO-treated ewes on both Days 9 and 12. On Day 125 of gestation, endometria from P4-treated ewes tended to have greater expression of SAT1 (P < 0.10) mRNA compared to CO-treated ewes. In contrast, the expression of AMD1(P < 0.01), MAT2B (P < 0.05), OAT (P < 0.05), SMOX (P < 0.05), and SLC12A8 (P < 0.05) mRNAs was lower in endometria from P4-treated compared to CO-treated ewes on Day 125. Exogenous P4 appeared to increase the relative abundance of SAT1 and SMOX proteins in the uterine luminal and glandular epithelia on Day 125 of pregnancy. These results suggest that early administration of progesterone may alter the biosynthesis of agmatine and polyamines in the sheep uterus during the pre-implantation period of pregnancy with potential ‘programming’ effects manifested in late pregnancy.

ITRAQ-based quantitative proteomic analysis of porcine uterine fluid during pre-implantation period of pregnancy

Proteins in the uterine luminal fluid are essential for embryo development and regulation of embryo-maternal interaction in porcine. However, little is known about the profile of proteins in uterine luminal fluid of porcine during the pre-implantation period. The present study, applied iTRAQ proteomics technology to identify and analyze uterine luminal fluid proteins on day 9 of estrus cycle and days 9, 12, and 15 of pregnancy. A total of 964 proteins were identified in the present study. Principal component analysis and hierarchical clustering revealed the dynamic developmental characteristics of embryo implantation, which indicated significant differences on day 12 or 15 of pregnancy. In addition, further analysis conducted in the present study identified 279 differentially abundance proteins among the three groups, five clusters were generated using SOTA clustering to examine changes in of the differentially abundant proteins. Results of the current study also found that the proteins in the cluster are involved in some important processes such as regulation of low-density lipoproteins and regulation of TGF-β secretion. Notably, it was found that regulation of TGF-β is essential for porcine embryonic morphological transformation. Furthermore, proteins that play vital roles in implantation, such as CTSC, CTSB, and ACP5 were identified through protein-protein interaction network. Therefore, these findings of the present study provide a basis for understanding embryo development mechanisms and implantation in pigs. SignificanceProteins are directly acting molecules for the functioning of organisms. It is important to study the regulation mechanism of embryo implantation from the perspective of protein function. In the current study, iTRAQ proteomics technology was employed to identify and explore uterine luminal fluid proteins on day 9 of estrus cycle and days 9, 12, and 15 of pregnancy. The findings provide novel insights into the process of porcine early embryo implantation. Furthermore, it is also helpful to clarify the mechanism of embryonic development and implantation.

GPx8 Expression in Rat Oocytes, Embryos, and Female Genital Organs During Preimplantation Period of Pregnancy.

This study aimed to detect the presence of glutathione peroxidase 8 (GPx8) in rat during preimplantation period of pregnancy. Females were killed on first (D1), third (D3), and fifth (D5) day of pregnancy. The presence of GPx8 in embryos was detected under the confocal microscope, the presence of GPx8 in genital organs was confirmed immunohistochemically, and the amount of GPx8 was determined using densitometry. We found that GPx8 is dispersed in the cytoplasm of oocytes, while after fertilization, it is concentrated in granules. From 4-cell stage till blastocyst, GPx8 reaction was found in the perinuclear region. In the ovary, GPx8 was seen in granulosa-lutein cells, in plasma of blood vessels, and inside Graafian follicles. In oviduct, GPx8 was detected in the plasma and in the extracellular matrix (ECM). Moreover, epithelial cells of isthmus were positive. In uterus, GPx8 was observed in the uterine glands, in the plasma, and in ECM. On D5, the enzyme disappeared from the uterine glands and appeared in fibroblasts. Densitometry revealed that the highest amount of GPx8 was on D1 and subsequently declined. To our knowledge, this is the first paper describing GPx8 presence in the oocytes, preimplantation embryos, and female genital organs in mammals. Our results improve the understanding of antioxidant enzymes presence during pregnancy in defense against oxidative stress, which is considered to be one of the main causes of infertility.

The role of CAPG in molecular communication between the embryo and the uterine endometrium: Is its function conserved in species with different implantation strategies?

During the preimplantation period of pregnancy in eutherian mammals, transcriptional and proteomic changes in the uterine endometrium are required to facilitate receptivity to an implanting blastocyst. These changes are mediated, in part, by proteins produced by the developing conceptus (inner cell mass and extraembryonic membranes). We hypothesized that this common process in early pregnancy in eutheria may be facilitated by highly conserved conceptus-derived proteins such as macrophage capping protein (CAPG). We propose that CAPG may share functionality in modifying the transcriptome of the endometrial epithelial cells to facilitate receptivity to implantation in species with different implantation strategies. A recombinant bovine form of CAPG (91% sequence identity between bovine and human) was produced and bovine endometrial epithelial (bEECs) and stromal (bESCs) and human endometrial epithelial cells (hEECs) were cultured for 24hours with and without recombinant bovine CAPG (rbCAPG). RNA sequencing and quantitative real-time PCR analysis were used to assess the transcriptional response to rbCAPG (Control, vehicle, CAPG 10, 100, 1000ng/mL: n=3 biological replicates per treatment per species). Treatment of bEECs with CAPG resulted in alterations in the abundance of 1052 transcripts (629 increased and 423 decreased) compared to vehicle controls. Treatment of hEECs with bovine CAPG increased expression of transcripts previously known to interact with CAPG in different systems (CAPZB, CAPZA2, ADD1, and ADK) compared with vehicle controls (P<.05). In conclusion, we have demonstrated that CAPG, a highly conserved protein in eutherian mammals, elicits a transcriptional response in the endometrial epithelium in species with different implantation strategies that may contribute to pregnancy success.

Epidermal growth factor: Porcine uterine luminal epithelial cell migratory signal during the peri-implantation period of pregnancy

The majority of early conceptus mortality in pregnancy occurs during the peri-implantation period, suggesting that this period is important for conceptus viability and the establishment of pregnancy. Successful establishment of pregnancy in all mammalian species depends on the orchestrated molecular events that transpire at the conceptus-uterine interface during the peri-implantation period of pregnancy. This maternal-conceptus interaction is especially crucial in pigs because they have a non-invasive epitheliochorial placentation during a protracted peri-implantation period. During the pre-implantation period of pregnancy, conceptus survival and the establishment of pregnancy depend on the developing conceptus receiving an adequate supply of histotroph which contains a wide range of nutrients and growth factors. Evidence links epidermal growth factor (EGF) to embryogenesis or implantation in various mammalian species. EGF exhibits potential growth-promoting activities on the conceptus and endometrium; however, in the case of pigs, little is known its functions, especially their regulatory mechanisms at the maternal-conceptus interface. EGF receptor (EGFR) mRNA and protein are abundant in endometrial luminal (LE) and glandular (GE) epithelia and conceptus trophectoderm on Days 13–14 of pregnancy, suggesting that EGF provides an autocrine signal to uterine LE and GE just prior to implantation. Therefore, the objectives of this study were to determine: 1) the potential intracellular signaling pathways responsible for the activities of EGF in porcine uterine LE (pLE) cells; and 2) the changes in cellular activities induced by EGF. EGF treatment of pLE cells increased the abundance of phosphorylated (p)-ERK1/2, p-P70RSK and p-RPS6 compared to that for control cells. Furthermore, EGF-stimulated phosphorylation of ERK1/2 MAPK was inhibited in pLE cells transfected with an EGFR siRNA compared with control siRNA-transfected pLE cells. Moreover, EGF stimulated migration of pLE cells, but this stimulatory effect was blocked by U0126, a pharmacological inhibitor or ERK1/2 MAPK. Collectively, these results provide new insights into mechanisms whereby EGF regulates development of the peri-implantation uterine LE at the fetal–maternal interface. These results indicate that endometrial- and/or conceptus derived EGF effects migration of uterine LE and that those stimulatory effects are regulated via the ERK1/2 MAPK pathway during early pregnancy in pigs.

Temporal regulation of fibroblast growth factors and their receptors in the endometrium and conceptus during the pre-implantation period of pregnancy in cattle

We hypothesised that the expression pattern of members of the fibroblast growth factor (FGF) family would be altered in the endometrium as the oestrous cycle/early pregnancy progressed associated with changes in the expression pattern of their receptors in the developing embryo/conceptus. Expression of FGF1 and FGF10 transcript variants 1 and 2 increased significantly as the oestrous cycle/early pregnancy progressed. Neither progesterone (P4) supplementation nor pregnancy status significantly affected the expression of any of the FGF ligands studied. However, there was a significant interaction between day, pregnancy and P4 status on FGF2 expression (P<0.05) and a significant interaction between P4 status and day on FGF10_tv2 expression. FGF10 protein was localised in the luminal and glandular epithelium as well as the stroma but was not detected in the myometrium. By RNA sequencing, the expression of FGF ligands in the developing embryo/conceptus was found to be minimal. The expression of FGF receptor 1 (FGFR1), FGFR2, FGFR3, FGFR4, FGFRL1 and FRS3 was significantly affected by the stage of conceptus development. Interestingly, the expression of FGFR1 and FGFR4 was higher during early embryo development (days 7-13, P<0.05) but decreased on day 16 (P<0.05) while FGFR2 (P<0.001) expression was similar from day 7 through to day 13, with a significant increase by day 16 (P<0.05) that was maintained until day 19 (P>0.05). In conclusion, these data demonstrate that FGF ligands are primarily expressed by the endometrium and their modulation throughout the luteal phase of the oestrous cycle/early pregnancy are associated with alterations in the expression of their receptors in the embryo/conceptus.

CD80 and CD86 costimulatory molecules differentially regulate OT-II CD4⁺ T lymphocyte proliferation and cytokine response in cocultures with antigen-presenting cells derived from pregnant and pseudopregnant mice.

Immune phenomena during the preimplantation period of pregnancy are poorly understood. The aim of our study was to assess the capacity for antigen presentation of splenic antigen-presenting cells (APCs) derived from pregnant and pseudopregnant mice in in vitro conditions. Therefore, sorted CD11c+ dendritic cells and macrophages F4/80+ and CD11b+ presenting ovalbumin (OVA) were cocultured with CD4+ T cells derived from OT-II mice's (C57BL6/J-Tg(TcraTcrb)1100Mjb/J) spleen. After 132 hours of cell culture, proliferation of lymphocytes (ELISA-BrdU), activation of these cells (flow cytometry), cytokine profile (ELISA), and influence of costimulatory molecules blocking on these parameters were measured. We did not detect any differences in regulation of Th1/Th2 cytokine balance. CD86 seems to be the main costimulatory molecule involved in the proliferation response but CD80 is the main costimulatory molecule influencing cytokine secretion in pregnant mice. In conclusion, this study showed that CD80 and CD86 costimulatory molecules regulate OT-II CD4+ T lymphocyte proliferation and cytokine response in cocultures with antigen-presenting cells derived from pregnant and pseudopregnant mice. The implications of these changes still remain unclear.

Lipopolysaccharide Drives Alternation of Heat Shock Proteins and Induces Failure of Blastocyst Implantation in Mouse

The objective of the present study is to investigate the role of heat shock proteins (Hsps) in preimplantation embryonic development and uterine receptivity during lipopolysaccharide (LPS)-induced pregnancy loss. Mice were treated with PBS or LPS on Day 0.5 of pregnancy, and preimplantation embryos and uterus were collected on Days 1.5-4.42 of pregnancy. The individual preimplantation embryos were assessed for their morphologic appearance and DNA damage during the preimplantation period of pregnancy. The expression of Hsp90, Hsp70, Hsp60, and Hsp25 was determined in preimplantation embryos and uterus by RT-PCR. Comet studies showed that LPS treatment significantly increased the percentage of abnormal embryos and DNA damage in the embryos. The expression of Hsp90, Hsp70, and Hsp60 was significantly lower in preimplantation embryos recovered from LPS-treated mice when compared to their respective controls. The expression of Hsp90, Hsp70, Hsp60, and Hsp25 was altered in uterus of LPS-treated mice when compared to their respective controls. Immunohistochemistry studies showed that at the time of implantation (i.e., Day 4.42), levels of Hsp90 and Hsp60 were decreased in stromal cells of LPS-treated uterus when compared to their respective controls. Hsp25 was highly expressed in the endometrium and stromal cells of LPS-treated uterus. Our results clearly showed that lowering of embryonic expression of Hsps induces DNA damage, which leads to degeneration and degradation of preimplantation embryos, and altered uterine expression of Hsps may not prepare the uterus for implantation. This may ultimately lead to implantation failure in mouse.

CD40, CD80, and CD86 Costimulatory Molecules are Differentially Expressed on Murine Splenic Antigen‐presenting Cells During the Pre‐implantation Period of Pregnancy, and they Modulate Regulatory T‐cell Abundance, Peripheral Cytokine Response, and Pregnancy Outcome

The object of the study was to investigate the costimulatory phenotype of spleen antigen-presenting cells (APCs) in mice after mating and the influence of costimulatory signal blocking on pregnancy outcome, cytokine production, and Treg cell concentration. The levels of CD40, CD80, and CD86 on spleen APCs at day 0.5 and 3.5 after mating (C57BL/6Jx DBA/2J and C57BL/6JxBalb/c) were assessed by flow cytometry and RT-PCR. Blocking antibodies against costimulatory molecules were given i.p. at day 3.5 after mating. Pregnancy outcomes, blood cytokine (ELISA), and spleen Treg (flow cytometry) concentrations were examined at day 10.5 after mating. Differential expression of costimulatory molecules on spleen APCs of mated v. pseudopregnant mice was observed mainly at day 3.5 after conception. Administration of anti-CD86 antibody lowered pregnancy outcome. Cytokine expression was modulated after administration of anti-CD86, anti-CD80 and anti-CD40 antibodies, whereas only anti-CD40 antibody changed the concentration of Treg lymphocytes and the level of Foxp3 protein expression. Costimulatory phenotype of female spleen APCs is distinctly modulated after mating. Alteration of costimulatory signal derived from APCs during pre-implantation period of pregnancy may have an adverse effect on pregnancy outcome and the tolerogenic immune response.

Effects of systemic progesterone during the early luteal phase on the availabilities of amino acids and glucose in the bovine uterine lumen

The uterine histotroph provides essential nutrition to the developing conceptus during the preimplantation period of pregnancy. The objective of the present study was to examine the effects of cycle stage and progesterone (P4) concentrations in the blood on the recoverable quantities of amino acids and glucose in the histotroph during the preimplantaion period of conceptus development. Following oestrus, dairy heifers were assigned to low, control or high P4 groups (n=6 heifers per treatment and time point). The uterine horn ipsilateral to the corpus luteum was flushed on either Day 7 or Day 13. The present study quantified 24 amino acids and glucose in the uterine flushings using HPLC and fluorometry, respectively. Heifers in the low P4 group had lower plasma concentrations of P4 throughout the cycle, whereas heifers in the high group had higher plasma concentrations of P4 between Days 3 and 7 compared with the control group (P<0.05). Total recoverable neutral (Ser, Gln, Gly, Thr, Cit, β-Ala, Tau, Ala, Tyr, Trp, Met, Val, Phe, Ile, Leu, Pro and Cys), acidic (Glu) and basic (His, Arg, Orn and Lys) amino acids were greater (P<0.05) on Day 13 than on Day 7. There was no significant difference in the amount of Asp or Asn between Day 7 and Day 13. The amount of amino acids recovered on Day 7 was similar across treatment groups. On Day 13, the amount of Asn, His and Thr was lower (P<0.05) in the low P4 heifers compared with the controls and/or high P4 heifers. Quantities of glucose were not altered by cycle stage or P4 treatment. In conclusion, the stage of oestrous cycle and P4 play important roles in modulating amino acids in the histotroph, a potentially critical factor for early embryonic and/or conceptus survival.

Gene expression downregulation of the main signaling pathways in the uterus is characteristic for preimplantation period of pregnancy in mice

Gene expression downregulation of the main signaling pathways in the uterus is characteristic for preimplantation period of pregnancy in mice

Non-surgical embryo transfer– a tool to study embryo-maternal interactions during pre-implantation period of pregnancy in mice

Non-surgical embryo transfer– a tool to study embryo-maternal interactions during pre-implantation period of pregnancy in mice

Antigen presenting cells costimulatory signaling during pre-implantation pregnancy

Success of pregnancy depends on many factors. Three phenomena inducing immune tolerance against semi-allogeneic conceptus may play a crucial role in the pre-implantation period of pregnancy: influence of sex hormones in sex cycle, presence of oocyte or embryo and the presence of semen in the female reproductive tract. On the other hand dendritic cells are the most effective antigen-presenting cells in regulation of immune phenomena and also are considered as potent participants in inducing immune tolerance in the pregnancy. They communicate with T cells in cell contact-dependent manner or via cytokines. During cell-cell contacts, costimulatory molecules play a key role and their expression is often dependent on cytokines milieu. Both costimulatory molecules and cytokines influence generation of T regulatory cells. Interactions of these molecules are closely related. In this paper we would like to pay attention to the importance of antigen presenting cells costimulatory potency in immune regulation during a pre-implantation period of pregnancy.

Genes Encoding for Secreted Proteins Increase During the Pre-Implantation Period of Pregnancy in the Bovine Endometrium and Are Modulated by Progesterone Concentrations In Vivo.

Genes Encoding for Secreted Proteins Increase During the Pre-Implantation Period of Pregnancy in the Bovine Endometrium and Are Modulated by Progesterone Concentrations In Vivo.

V-ATPase upregulation during early pregnancy: a possible link to establishment of an inflammatory response during preimplantation period of pregnancy

Various mechanisms exist to prevent a potentially deleterious maternal immune response that results in compromising survival of semiallogeneic fetus. In pregnancy, there is a necessary early preimplantation inflammatory stage followed by a postimplantation anti-inflammatory stage. Thus, there is a biphasic 'immune response' observed during the course of pregnancy. We provide the evidence that capacitation of sperm induced the expression of a2 isoform of V-ATPase (ATP6V0A2 referred to as a2V), leukemia inhibitory factor (Lif), Il1b, and Tnf in the sperm. Capacitated sperm also released cleaved N-terminal domain of a2V-ATPase (a2NTD), which upregulates the gene expression of Lif, Il1b, Tnf, and monocyte chemotactic protein-1 (Ccl2 (Mcp1)) in the uterus. Unfertilized eggs had low a2V expression, but after fertilization, the expression of a2V increased in zygotes. This increased level of a2V expression was maintained in preimplantation embryos. Seminal plasma was necessary for upregulation of a2V expression in preimplantation embryos, as mating with seminal vesicle-deficient males failed to elicit an increase in a2V expression in preimplantation embryos. The infiltration of macrophages into the uterus was significantly increased after insemination of both sperm and seminal plasma during the preimplantation period of pregnancy. This dynamic infiltration into the uterus corresponded with the uterine a2V expression through the induction of Ccl2 expression. Furthermore, the polarization ratio of M1:M2 (pro-inflammatory/anti-inflammatory) macrophages in the uterus fluctuated from a ratio of 1.60 (day 1) to 1.45 (day 4) when female mice were inseminated with both sperm and seminal plasma. These data provide evidence that exposure to semen may initiate an inflammatory milieu by inducing a2V and cytokine/chemokine expression, which triggers the influx of macrophages into the preimplantation uterus during the onset of pregnancy and ultimately leads to successful pregnancy outcome.

Activity of Monoamine Oxidases in Rat Female Genital Organs During Preimplantation Period of Pregnancy

Activity of Monoamine Oxidases in Rat Female Genital Organs During Preimplantation Period of PregnancyOur objectives in the present study were to determine the activity of monoamine oxidases A and B (MAO AB) in rat ovary, oviduct and uterus during preimplantation period of pregnancy. It should help us to clarify and better understand possible involvement of both MAO enzymes in the reproductive process. Pregnant females were killed employing a lethal dose of thiopental on the first (D1), on the third (D3), and on the fifth (D5) days of pregnancy. Rats were perfused transcardially with the PBS to rinse out of the body as much blood as possible. Ovaries, oviducts and uteri were immediately removed and stored until the measurement was done. MAO activity was determined by fluorescent monoamine oxidase detection kit. In the ovaries we have found the highest MAO activity at D3, followed by D1, and the lowest levels were recorded at D5 of pregnancy. In the oviducts, the highest MAO activity was detected again at D3, followed by D5, and by D1 of pregnancy. But statistical analysis did not reveal any difference between individual days of pregnancy nor in the ovaries, neither in uterine tubes. Uteri were the only organs, in which statistically significant differences were detected (p&lt;0.001). The highest activity of MAO was observed at D5, followed by D1, and by D3 of pregnancy. Potential mechanisms responsible for the changed MAO activity in gonads during preimplantation period of pregnancy are proposed.

LEFTY2 expression and localization in rat oviduct during early pregnancy

In mammals, fertilization and preimplantation embryo development occurs in the oviduct. Cross-talk between the developing embryos and the maternal reproductive tract has been described in such a way as to show that the embryos modulate the physiology and gene expression of the oviduct. Different studies have indicated that transforming growth factor beta (TGF-β) can modulate the oviductal microenvironment and act as an autocrine/paracrine factor on embryo development. LEFTY2, a novel member of the TGF-β superfamily is involved in the negative regulation of other cytokines in this family such as nodal, activin, BMPs, TGF-β1 and Vg1. In previous studies, we have reported that LEFTY2 is differentially expressed in the rat oviduct during pregnancy. In this study, we describe the temporal pattern of LEFTY2 in pregnant and non-pregnant rat oviduct by western blotting, which showed higher levels of LEFTY2 on day 4 of pregnancy, a time at which the embryos are ending their journey along the oviduct. The cellular location of LEFTY2 was assessed by immunohistochemistry, which showed immunolabelling in the cytoplasm and at the apical surface of the oviductal epithelial cells. The oviductal fluid also presented a 26 kDa band, which corresponds to the biologically active form of this protein, at the preimplantation period of pregnancy, indicating LEFTY2 secretion to the lumen. As LEFTY2 is expressed at a high level just before the embryos pass to the uterus, its biological effect might be relevant and significant for the preimplantation stage of embryo development in the oviduct. The fact that embryos do not express LEFTY2 at this stage of development supports this hypothesis.

Bacterial endotoxin (LPS)–induced DNA damage in preimplanting embryonic and uterine cells inhibits implantation

To investigate lipopolysaccharide (LPS)-induced DNA damage in preimplanting embryonic and uterine cells during preimplantation period of pregnancy that may ultimately inhibit the process of implantation in mouse. Animal study. Academic research environment. Sixty four Park strain female mice. The "minimum dose" (MD) of LPS was injected intraperitoneally in the pregnant females on day 0.5 of pregnancy, and individual embryos and uterine cells were assessed by comet assay on days 1.5, 2.5, 3.5, and 4.375 of the preimplantation period of pregnancy. Percentage of embryos and uterine cells with tail, mean comet tail length, percentage of fragmented DNA in tail. Significantly higher numbers of embryos with higher mean comet tail length and percentage of fragmented DNA in tail were observed in the LPS-treated compared with control animals as the period of pregnancy approaches the stage of implantation. At the same time, DNA damage was also significantly higher in the uterine cells of LPS-treated compared with control animals. The MD of LPS can induce DNA damage in the preimplantation-stage embryos and uterine cells, which causes poor embryonic development and improper preparation of uterine horns during the preimplantation period of pregnancy, which may ultimately inhibit the process of implantation in mouse.

Molecular mechanisms involved in progesterone receptor regulation of uterine function

The ovarian steroid hormone progesterone is a major regulator of uterine function. The actions of this hormone is mediated through its cognate receptor, the progesterone receptor, Pgr. Ablation of the Pgr has shown that this receptor is critical for all female reproductive functions including the ability of the uterus to support and maintain the development of the implanting mouse embryo. High density DNA microarray analysis has identified direct and indirect targets of Pgr action. One of the targets of Pgr action is a member of the Hedgehog morphogen Indian Hedgehog, Ihh. Ihh and members of the Hh signaling cascade show a coordinate expression pattern in the mouse uterus during the preimplantation period of pregnancy. The expression of Ihh and its receptor Patched-1, Ptc1, as well as, down stream targets of Ihh- Ptch1 signaling, such as the orphan nuclear receptor COUP- TF II show that this morphogen pathway mediates communication between the uterine epithelial and stromal compartments. The members of the Ihh signaling axis may function to coordinate the proliferation, vascularization and differentiation of the uterine stroma during pregnancy. This analysis demonstrates that progesterone regulates uterine function in the mouse by coordinating the signals from the uterine epithelium to stroma in the preimplantation mouse uterus.