Endometrial Protein Secretion Research Articles

Profile of Endometrial Secretory Proteins in Repeat Breeder Jersey Crossbred Cows

Profile of Endometrial Secretory Proteins in Repeat Breeder Jersey Crossbred Cows

The WNT signaling antagonist Dickkopf-1 directs lineage commitment and promotes survival of the preimplantation embryo.

Successful embryonic development is dependent on factors secreted by the reproductive tract. Dickkopf-1 (DKK1), an antagonist of the wingless-related mouse mammary tumor virus (WNT) signaling pathway, is one endometrial secretory protein potentially involved in maternal-embryo communication. The purpose of this study was to investigate the roles of DKK1 in embryo cell fate decisions and competence to establish pregnancy. Using in vitro-produced bovine embryos, we demonstrate that exposure of embryos to DKK1 during the period of morula to blastocyst transition (between d 5 and 8 of development) promotes the first 2 cell fate decisions leading to increased differentiation of cells toward the trophectoderm and hypoblast lineages compared with that for control embryos treated with vehicle. Moreover, treatment of embryos with DKK1 or colony-stimulating factor 2 (CSF2; an endometrial cytokine known to improve embryo development and pregnancy establishment) between d 5 and 7 of development improves embryo survival after transfer to recipients. Pregnancy success at d 32 of gestation was 27% for cows receiving control embryos treated with vehicle, 41% for cows receiving embryos treated with DKK1, and 39% for cows receiving embryos treated with CSF2. These novel findings represent the first evidence of a role for maternally derived WNT regulators during this period and could lead to improvements in assisted reproductive technologies.

KLFII Epigenetically Regulates Glycodelin-A, a Marker of Endometrial Biology Via Histone-Modifying Chromatin Mechanisms

Endometrial biology is characterized by programmed proliferation and differentiation that is synchronous with ovarian folliculogenesis to maximize the chance of pregnancy. Glycodelin-A, an endometrial secretory protein, promotes pregnancy mostly through immunomodulatory mechanisms. Glycodelin-A is repressed during the proliferative and early secretory phase and activated thereafter. Progesterone activates glycodelin via the Sp1 (Specificity Protein 1) transactivator. We identify a novel role for Kruppel-like transcription factor 11 (KLF11) as a glycodelin-A repressor. Although KLF11 bound 2 distinct regulatory elements, it regulated glycodelin promoter activity differentially through each element. Whereas KLF11 weakly activated glycodelin promoter activity via a region that also bound Sp1, the dominant effect of KLF11 was repression of promoter activity, messenger RNA (mRNA), and protein expression via a novel, specific binding element. KLF11 mediated this repression by recruiting the SIN3/histone deacetylase (HDAC) corepressor complex to the glycodelin promoter. KLF11 may solely, or by competing with Sp1, repress glycodelin-A levels and thereby influence its role in the endometrium.

Morpho-functional studies regarding the fertility prognosis of mares suffering from equine endometrosis

The aim of the present study was to characterize the morpho-functional features of endometrosis in barren and foaling mares, using both conventional histopathological and immunohistochemical methods. Endometrial biopsy samples were collected during the physiological breeding season from 159 estrous, clinically healthy mares (mean age 12 years), and the quality and degree of endometrosis was histomorphologically defined. The mares were bred and those that foaled were put in the foaling group whereas those that did not foal were placed in the barren group. Foaling mares were then compared with barren mares. Sixty-four percent (101/159) of uterine samples showed varying degrees of endometrosis and were used for this study. The sample population consisted of 51 barren and 50 foaling mares suffering from endometrosis. Expression of steroid hormone receptors (estrogen receptor, progesterone receptor) and endometrial protein secretion patterns (uteroglobin [UG], uterocalin [UC], calbindinD9k [CAL], uteroferrin [UF]) was evaluated by immunohistochemistry (barren mares N = 51, foaling mares N = 31). In comparison with unaffected glands, fibrotic glands generally showed a cycle-asynchronous, partially patchy protein expression pattern which is interpreted as a sign of endometrial maldifferentiation within fibrotic areas. In barren mares (N = 51) more than half of biopsy samples (27/51) showed a destructive mostly moderate (20/27) type of endometrosis. In affected glands, staining for UG (17/21) was decreased (P < 0.001). Foaling mares (N = 50) frequently showed a mild, nondestructive endometrosis (35/50). Compared with barren mares, foaling mares had statistically (P < 0.05) more often a cycle-synchronous or increased UG expression pattern within fibrotic glands. Obvious deviations of either UG or UC rarely occurred. Within fibrotic foci, UF often demonstrated a cycle-synchronous or more intense expression pattern in both foaling (28/31) and barren mares (41/51), compared with healthy glands. Mares of both groups showed a cycle-asynchronous staining for estrogen receptor and progesterone receptor in the stromal cells in areas of periglandular fibrosis and the glandular epithelia. These findings indicate that affected areas become independent of the uterine control mechanisms and exhibit specific differentiation dynamics. Immunohistochemical investigations showed that the secretory patterns differ between barren and foaling mares. The findings in this study should be considered as a useful addition to the “classical” Kenney categorization.

Patterns of Hormonally Regulated Endometrial Secretory Proteins as Detected by a Protein Chip Microarray

Cytokines contribute to preimplantation endometrial development. Here we study steroid control of cytokines in a mouse endometrial model. Immature mouse endometrial cells were cultured with different hormonal media. Protein expression patterns were studied with a protein microarray. Endometrial cells were cultured from immature 3-week old brown BDF1 mice (Charles River Co., MA) The enzymatically digested glands and stroma (0.2x106 cell density) were seeded in four groups and incubated for 10 days with different hormonal media: Control, Estradiol (E2, 1x10-8 Molar), Progesterone (P, 1x10-8M) and E2+P. Protein array membranes for the detection of multiple cytokines at concentrations of 10 to 10,000 pg/ml (RayBio® Mouse Cytokine Antibody Array III) were incubated in serum free medium obtained from each group on day 10. The membranes were prepared per protocol and exposed to x-ray film. Primary analysis of the membranes was performed using Discovery Series Quantity One software (BioRad, CA). Expression was measured as the array spot area (mm2) x the optical density (OD). Mouse β-actin was amplified by RT-PCR as an internal control. Cell characteristics revealed hormonal differences in growth. E2 treated cells appeared longer and after 5 days proliferated in an overlapping, less orderly manner. P cells appeared fat and globular with large nuclei and abundant cytoplasm. E2+P cells grew abundantly and developed several glandular structures by day 8. RT-PCR was performed to confirm decidualization of cells by detection of decidual/trophoblastic prolactin-related protein (d/tPRP) mRNA in PCR products of P and E2+P treated cells (Kimura F et al., Gynecol Endocrinol 2001;15: 426-432). Of 62 cytokines, 41 were consistently detected by the array: L-selectin, Macrophage Inflammatory Protein-1α (MIP-1α), Vascular Cell Adhesion Molecule-1 (VCAM-1), Monocyte Chemo-attractant Protein-1 (MCP1), RANTES, and lymphotactin were expressed moderately strongly (OD>.04), and P-selectin and Tissue inhibitor of Metalloproteinase-1 (TIMP-1) were expressed most strongly (OD > .06). Cytokine array values were compared to control cell values for influence of hormonal treatment: E2 treatment increased secretion of 3 proteins, inhibited 22, and did not affect 13; P treatment increased secretion of 4, inhibited 19, and did not affect 8; E2+P treatment increased secretion of 9, decreased 26 and did not affect 6. Fractalkinine secretion was increased by both E2 and P alone but inhibited by E2+P. Secretion of eotaxin, eotaxin-2, and Interleukin-2 (IL-2) was not affected by E2 or P alone but was stimulated by E2+P. IGFBP-3, Macrophage Colony Stimulating Factor, MIP-3β, Soluble Tumor Necrosis Factor Receptor II, VEGF, and TIMP-1 were inhibited equally by E2, P and E2+P. MCP-1, MIP-2, Regulated upon Activation Normal T cell Expressed and Secreted (RANTES), and VCAM-1 were inhibited by E2 and P alone and further by E2+P. The simultaneous detection of multiple cytokines in a cultured mouse endometrial model suggests a steroid-based coordination of cytokines involved in implantation. Specific proteins demonstrated similar patterns of hormonal secretion, suggesting a common synthetic pathway or biologic function. These findings may be applied to create a more favorable milieu for embryo co-culture and to further study implantation.

GnRH II as a possible cytostatic regulator in the development of endometriosis

GnRH II is the second form of GnRH and is widely distributed in peripheral tissues of the female reproductive tract as well as in the central nervous system. In the present study, we studied the possible implication of GnRH II in endometriosis. Effects of GnRH II on 5-bromo-2'-deoxyuridine (BrdU) uptake by cultured endometriotic stromal cells were examined. Effects of GnRH II on interleukin (IL)-1beta-induced expression of cyclooxygenase (COX)-2 and IL-8 were also studied. mRNA levels of GnRH I, GnRH II, type I GnRH receptor and type II GnRH receptor were determined by real-time quantitative RT-PCR in endometrial tissues of women with or without endometriosis and in endometriotic tissues. GnRH II dose-dependently suppressed BrdU uptake by endometrial stromal cells. Treatment with IL-1beta markedly increased mRNA levels of COX-2 and IL-8 in endometrial stromal cells and IL-8 protein secretion by these cells, while these increments were significantly suppressed by supplementation with GnRH II. The mRNA levels of GnRH II were lower in endometrial and endometriotic tissues of women with endometriosis than in endometrial tissues of women without endometriosis, both in the proliferative phase and the secretory phase. In addition, as for GnRH I, type I GnRH receptor and type II GnRH receptor, the mRNA levels were lower in endometrial tissues of women with endometriosis than in those without endometriosis in the secretory phase. In the light of the demonstrated antiproliferative and anti-inflammatory effects of GnRH II on endometrial stromal cells, the lower expression of GnRH II in eutopic and ectopic endometrium of women with endometriosis suggests that endogenous GnRH II-mediated cytostatic regulation may be impaired in the development of endometriosis.

A PREGNANCY-ASSOCIATED GLYCOPROTEIN (PAG) UNIQUE TO THE ROE DEER (CAPREOLUS CAPREOLUS) AND ITS ROLE IN THE TERMINATION OF EMBRYONIC DIAPAUSE AND MATERNAL RECOGNITION OF PREGNANCY

During reactivation of the roe deer blastocyst from embryonic diapause, the conceptus secretes a unique protein. The conceptuses were cultured individually in vitro with a radiolabel to establish de novo protein synthesis. Endometrial tissue from the same does was also cultured in vitro to establish radiolabel incorporation into endometrial secretions during blastocyst reactivation. Incorporation into secretory proteins from the blastocysts showed a significant increase during reactivation (p < 0.05) whereas incorporation into endometrial secretory proteins remained constant. The secretory proteins from the conceptus were identified using electrophoresis and fluorography as having the same molecular weight and pI as pregnancy-associated glycoproteins (PAGs). Fluorography clearly identified a single PAG with a molecular weight of 66 kDa and an isoelectric point (pI) of 6.2. Previous research shows these blastocyst secretions target endometrial receptors. The current study demonstrates this is followed by a...

Glycodelin gene expression in human peripheral white blood cells

Glycodelin is an endometrial secretory protein having immunosuppressive effects. It is produced by secretory endometrial glands. Glycodelin facilitates implantation by inhibiting the immune response of the endometrium to the embryo. Decreased plasma glycodelin levels are associated with abnormal endometrial development and recurrent pregnancy loss. Although the role of glycodelin has been evaluated within the endometrium, its role in the peripheral circulation has not been determined. We evaluated circulating leukocytes from normal healthy subjects for the presence of glycodelin gene expression.

Serum placental protein 14: a novel marker of selective oestrogen receptor modulator action on the postmenopausal endometrium

The primary objective of this study was to investigate whether changes in the serum level of an endometrial secretory protein, placental protein 14 (PP14), can reflect endometrial adverse events induced by selective oestrogen receptor modulators (SERMs). A randomized, double-blind, placebo-controlled trial was used. Participants were healthy postmenopausal women aged 45-65 years, who received either various doses of raloxifene (30, 60 or 150mg day-1) or levormeloxifene (1.25, 5, 10 or 20 mgday-1) or placebo for 12months. Serum PP14 and endometrial thickness (ET) were monitored by radioimmunoassay and transvaginal ultrasonography, respectively. In the levormeloxifene trial, endometrial status at 12 months was assessed by hysteroscopy. Raloxifene induced only slight increases in serum PP14 and ET. Levormeloxifene, however, induced marked increases in both study parameters at all the does tested. The 6month changes in PP14 showed a positive correlation with both the 6 and 12month changes in ET (P < 0.001). Marked stromal oedema, pseudocysticity with or without hypervascularity and endometrial proliferation were seen on hysteroscopy in those showing the largest increases in serum PP14. These results suggest that the PP14 assay used on a group basis may provide useful information on the endometrial effects of SERMs administered in a given dose range, and thereby could assist future clinical trials aiming to find the optimal dose range of new SERMs.

Temporal changes in reproductive hormones and conceptus-endometrial interactions during embryonic diapause and reactivation of the blastocyst in European roe deer (Capreolus capreolus)

The roe deer blastocyst is in diapause between August and December, after which time it expands and elongates rapidly before implantation. Blood samples were taken from 30 animals to define temporal changes in reproductively important hormones to investigate the physiological cues present at embryo reactivation. In 15 of these animals, changes in uterine and conceptus protein synthesis and secretion, and luteal progesterone release during diapause and reactivation, were assessed after culture of these tissues in vitro. Oestradiol concentrations remained low during diapause (1.07 +/- 0.4 pg ml(-1)) and expansion (1.2 +/- 0.4 pg ml(-1)) but increased by 30 times at trophoblast elongation (49.17 +/- 0.37 pg ml(-1)). Prolactin remained at basal concentrations (4.69 +/- 0.86 ng ml(-1)) and increased after implantation (12.34 +/- 2.71 ng ml(-1)). Peripheral progesterone concentrations and luteal progesterone release remained constant throughout diapause, reactivation and implantation (peripheral progesterone: 3.82 +/- 1.97 ng ml(-1); luteal progesterone: 6.72 +/- 0.81 ng mg(-1) protein). Incorporation of a radiolabel into conceptus secretory proteins increased by four times at expansion compared with diapause, whereas incorporation into endometrial secretions remained constant. At elongation, incorporation into endometrial secretions increased two times and conceptus secretions increased 32 times. Two-dimensional electrophoresis and fluorography showed that the profile of endometrial secretory proteins was constant until implantation when qualitative changes were evident. Although a role for an endocrine maternal trigger of reactivation from diapause cannot be dismissed, these data provide no supporting evidence and indicate that the conceptus itself may drive reactivation.

Temporal changes in reproductive hormones and conceptus-endometrial interactions during embryonic diapause and reactivation of the blastocyst in European roe deer (Capreolus capreolus)

The roe deer blastocyst is in diapause between August and December, after which time it expands and elongates rapidly before implantation. Blood samples were taken from 30 animals to define temporal changes in reproductively important hormones to investigate the physiological cues present at embryo reactivation. In 15 of these animals, changes in uterine and conceptus protein synthesis and secretion, and luteal progesterone release during diapause and reactivation, were assessed after culture of these tissues in vitro. Oestradiol concentrations remained low during diapause (1.07 +/- 0.4 pg ml(-1)) and expansion (1.2 +/- 0.4 pg ml(-1)) but increased by 30 times at trophoblast elongation (49.17 +/- 0.37 pg ml(-1)). Prolactin remained at basal concentrations (4.69 +/- 0.86 ng ml(-1)) and increased after implantation (12.34 +/- 2.71 ng ml(-1)). Peripheral progesterone concentrations and luteal progesterone release remained constant throughout diapause, reactivation and implantation (peripheral progesterone: 3.82 +/- 1.97 ng ml(-1); luteal progesterone: 6.72 +/- 0.81 ng mg(-1) protein). Incorporation of a radiolabel into conceptus secretory proteins increased by four times at expansion compared with diapause, whereas incorporation into endometrial secretions remained constant. At elongation, incorporation into endometrial secretions increased two times and conceptus secretions increased 32 times. Two-dimensional electrophoresis and fluorography showed that the profile of endometrial secretory proteins was constant until implantation when qualitative changes were evident. Although a role for an endocrine maternal trigger of reactivation from diapause cannot be dismissed, these data provide no supporting evidence and indicate that the conceptus itself may drive reactivation.

Trans-activation functions of the Sp-related nuclear factor, basic transcription element-binding protein, and progesterone receptor in endometrial epithelial cells.

The present study examined the trans-activation potential of basic transcription element-binding protein (BTEB), a recently identified member of the Sp family of GC box-binding transcription factors, on the expression of the gene encoding the pregnancy-associated, epithelial-specific, and progesterone (P)-induced porcine uterine endometrial secretory protein, uteroferrin (UF). Endometrial expression of BTEB, P receptor (PR), and UF genes was analyzed by RT-PCR as a function of pregnancy stage and cell type and was correlated with the levels of endometrial BTEB that were quantified by Western blot and/or electrophoretic mobility shift assay. PR, BTEB, and UF messenger RNAs (mRNAs) were present in early (day 12) and mid(day 60) pregnancy pig endometrium, although expression levels varied for each mRNA (UF, day 12 << day 60; PR and BTEB, day 12 = day 60). Within the endometrium, glandular epithelial (GE) cells manifested higher amounts of UF mRNA than stromal fibroblastic cells, whereas both cell types had comparable amounts of BTEB and PR mRNAs. Expression of BTEB, however, was limited to endometrial GE cells. A BTEB expression vector (pcDNA-3BTEB) was used to examine the effect of increased BTEB protein on UF gene expression and promoter activity in primary cultures of pig endometrial GE cells. Cells transiently transfected with pcDNA-3BTEB had 2-fold higher UF mRNA levels than those transfected with the empty expression vector (pcDNA-3). Further, cells cotransfected with a UF promoter-luciferase (-1935UF-Luc) reporter gene and the BTEB expression vector had 2-fold higher Luc activity than those cotransfected with reporter gene and pcDNA-3. This effect of BTEB was not observed in transfected endometrial stromal fibroblastic cells, but was apparent in the human endometrial epithelial carcinoma cell lines ECC-1 and Hec-1-A, which exhibit low levels of BTEB protein and low or undetectable PR mRNA levels, respectively. The respective contributions of BTEB and PR to the modulation of UF promoter activity were examined by cotransfection of Hec-1-A and ECC-1 cells with expression plasmids for BTEB and PR and one of two UF promoter constructs (-831UF-Luc or -1935UF-Luc) in the absence or presence of P. The increase in UF promoter activity with BTEB was mimicked by PR in a P-dependent manner in both cell lines. The combined effect of PR/P and BTEB appeared additive in Hec-1-A cells and was synergistic in ECC-1 cells. These results highlight the cell context dependence of the trans-activation potential of BTEB and suggest its unique role, in concert with PR, in directing the temporal expression of endometrial epithelial genes of pregnancy.

Conceptus-endometrial interactions and reproductive hormone profiles during embryonic diapause and reactivation of the blastocyst in the European roe deer (Capreolus capreolus)

&lt;p&gt;Abstract: Roe deer blastocysts exhibit obligate embryonic diapause between early August and late December. The blastocyst then expands and elongates rapidly before implantation. The objective of this study was to ascertain the cues for reactivation of the diapausing blastocyst. Blood samples and reproductive tracts were collected from roe does during diapause, blastocyst expansion and subsequent implantation. Peripheral concentrations of oestradiol-17/3, progesterone and prolactin were measured by radioimmunoassay. Luteal progesterone release was determined following in vitro incubation. Conceptuses and endometrial tissue were cultured with 3H-leucine for 24 hours to measure de novo synthesis of secretory proteins. Endometrial secretory proteins were separated by two-dimensional electrophoresis. Results showed that peripheral progesterone concentrations declined by 55% just prior to expansion and did not rise until a 3-fold increase after implantation. Luteal progesterone release remained constant until expansion when it declined by 50% before increasing 2-fold at elongation and implantation. Concentrations of oestradiol-17/3 remained at a consistently low level during diapause and expansion until a 30-fold increase at elongation with concentrations remaining elevated after implantation. Plasma prolactin levels remained at basal concentrations during late diapause and then increased marginally at reactivation before decreasing again at elongation and implantation. Incorporation of radiolabel into both conceptus and endometrial secretory proteins was low during diapause, but incorporation in the conceptus increased 4&amp;not;fold at expansion and by 24-fold at the expanded trophoblast stage. Incorporation into endometrial secretoty proteins remained constant until the expanded trophoblast stage and implantation when a 2-fold increase was recorded. Furthermore, the profile of endometrial secretory proteins was constant during diapause and expansion but changed qualitatively following implantation. These data indicate that both endometrial protein synthesis and sectetion did not change during late diapause and early expansion. The increase in conceptus protein synthesis not only precedes that of the endometrium but consistently low luteal progesterone release, peripheral progesterone and oestradioi-17/J concentrations at early expansion suggests that reactivation is not in response to a maternal uterine trigger.&lt;/p&gt;

Serum levels of human placental lactogen, pregnancy‐associated plasma protein A and endometrial secretory protein PP14 in first trimester of diabetic pregnancy

To study maternal serum levels of human placental lactogen (hPL), pregnancy-associated plasma protein A (PAPP-A) and endometrial secretory protein PP14 (PP14) in first trimester of diabetic pregnancy. Seventy-nine insulin-dependent diabetic women and 93 normal pregnant women had a venous blood sample drawn in weeks 8-14, ultrasound age. Serum levels were measured by radioimmunoassays and expressed in multiples of the median serum value in normal pregnancy at that ultrasound age. Levels of hPL were significantly lower in diabetic mothers than in controls, z'= -5.502, p<0.00001. Levels of PAPP-A were also significantly lower, z' =2.263, p=0.024, but were significantly less depressed than those of hPL, z'=2.41, p=0.015. The PP14 levels did not deviate from normal. In first trimester of diabetic pregnancy there appears to be both a more general depression of trophoblast function, and also a specific depression of the hPL release.

Serum levels of human placental lactogen, pregnancy-associated plasma protein A and endometrial secretory protein PP14 in first trimester of diabetic pregnancy

Serum levels of human placental lactogen, pregnancy-associated plasma protein A and endometrial secretory protein PP14 in first trimester of diabetic pregnancy

Bovine endometrial retinol-binding protein secretion, messenger ribonucleic acid expression, and cellular localization during the estrous cycle and early pregnancy.

Retinol-binding protein (RBP) mRNA was localized to luminal and glandular epithelial cells of bovine endometrium by in situ hybridization. Relative levels of endometrial RBP mRNA expression during the estrous cycle and early pregnancy were determined by quantitative slot blot analysis and contrasted with uterine luminal concentrations of RBP. Expression of mRNA was moderate at Day 1 after estrus, declined at Day 5, reached lowest levels by Day 10, rose significantly through Days 15-17, and peaked at Day 20. RBP mRNA expression in pregnant animals was similar to that in cyclic animals on Day 15, doubled between Days 17 and 20, remained constant through Day 22, and rose slightly thereafter. Luminal RBP concentrations of cyclic cows, as determined by ELISA, decreased from Day 1 through Day 10, rose dramatically on Day 15, then declined through Day 20. Concentrations of RBP in uterine flushes from pregnant animals were similar to those of cyclic cows on Day 15 but remained relatively constant through Day 17. It is concluded that 1) RBP synthesis occurs in the luminal and glandular epithelial cells, 2) RBP transcription and secretion are correlated with each other, and 3) ovarian steroids, possibly in conjunction with uterine concentrations of their receptors, modulate uterine RBP expression.

Symposium: reproduction in baboons. Secretory proteins of the baboon (Papio anubis) endometrium: regulation during the menstrual cycle and early pregnancy

The biological function of uterine endometrial secretory proteins in the primate remain to be elucidated. In general, during the luteal phase and under progesterone dominance, the glandular epithelial cells synthesize and secrete a number of proteins. Of these, placental protein 14 (PP14; now referred to as glycodelin) and insulin-like growth factor binding protein-1 (IGFBP-1) are the best characterized. Although induced by progesterone, their synthesis increases exponentially during pregnancy. In the baboon, glycodelin is immunolocalized to the mid functionalis and basal glands between days 10 and 12 post-ovulation. In response to either exogenous or blastocyst-secreted chorionic gonadotrophin, glandular synthesis increases markedly and remains elevated up to days 18-25 of pregnancy. The decrease in glycodelin in the endometrium is associated with glandular regression during the first third of pregnancy. In contrast, IGFBP-1 is only observed in the deep basal glands during the luteal phase. Following the establishment of pregnancy, IGFBP-1 synthesis switches from glandular to stromal and is correlated with the process of decidualization. IGFBP-1 synthesis continues to increase throughout gestation. We propose that glycodelin may have immunosuppressive properties and that IGFBP-1 may regulate trophoblast migration within the uterine endometrium.

Interrelationships of protein and oestradiol secretion by conceptuses and endometrium from Meishan pigs on days 11–15 of pregnancy

The second week after mating is recognised as critical to the successful maintenance of pregnancy in the pig, and is believed to be when Meishan females gain much of their reproductive advantage. In this experiment, the composition of uterine fluids, and conceptus and endometrial culture medium was examined in 14 Meishan gilts on Days 11–15 of pregnancy. Positive relationships were detected between blastocyst size and both oestradiol secretion (P < 0.05) and the incorporation of radiolabelled leucine into conceptus secretory proteins (P < 0.05). The incorporation of radiolabel was also related to oestradiol secretion (P < 0.01) in individual littermate spherical and ovoid conceptuses. Although there were no consistent temporal changes in the endometrial secretory protein profile, two proteins believed to be retinol binding proteins were absent from uterine flushes on Day 11, but present on all subsequent days. In conceptus culture medium, acidic proteins were predominant on Days 12 and 13, while basic proteins predominated on Days 14 and 15. Conceptus secretion of proteins with antiviral activity, detected on Days 14 and 15, was reduced by almost 50% when conceptuses were cultured in the presence of endometrial tissue. These data provide valuable new information on the biochemical dialogue occurring between Meishan conceptuses and the endometrium during a critical stage of pregnancy, and can be considered to reveal interactions characteristic of prolific pigs.

Serum relaxin and the major endometrial secretory proteins in in-vitro fertilization and down-regulated hormone-supported and natural cycle frozen embryo transfer.

Relaxin has been postulated to be a modulator of the expression of the endometrial secretory proteins, insulin-like growth factor binding protein (IGFBP-1) and placental protein 14 (PP14). This study evaluated the expression of relaxin in relation to concentrations of these secretory proteins along with oestradiol, progesterone and human chorionic gonadotrophin in groups of pregnant and non-pregnant patients who underwent differing assisted conception treatments. Serum samples were taken from 88 patients at 8 and 12 days after embryo transfer. At 12 days after embryo transfer, relaxin concentrations in the pregnant patients who had undergone in-vitro fertilization (IVF) or natural cycle frozen embryo transfer were significantly higher than those who did not conceive in these groups (mean concentrations 8334 versus 28 and 2608 versus 62 pg/ml respectively, P<0.001). However concentrations in the pregnant patients who had hormone support and transfer of frozen embryos were not significantly different from the patients who did not conceive after the same treatment. Although relaxin expression was associated with corpus luteum activity, it was not related to the number of corpora lutea in IVF patients. A wide range of relaxin concentrations was seen to be compatible with a healthy pregnancy. These serum relaxin concentrations were not found to be directly related to the serum concentrations of IGFBP-1, PP14 or the other factors assessed in this study.

The effect of estrone and estradiol treatment on endometrial total protein, uteroferrin, and retinol-binding protein secretion during midpregnancy or midpseudopregnancy in swine.

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.