Characterization of the interleukin-1beta system during porcine trophoblastic elongation and early placental attachment

Conceptus-uterine communication is established during trophoblastic elongation when the conceptus synthesizes and releases estrogen, the maternal recognition signal in the pig. Interleukin-1beta (IL-1beta) is a differentially expressed gene during rapid trophoblastic elongation in the pig. The current investigation determined conceptus and endometrial changes in gene expression for IL-1beta, IL-1 receptor antagonist (IL-1Rant), IL-1 receptor type 1 (IL-1RT1), and IL-1 receptor accessory protein (IL-1RAP) in developing peri- and postimplantation conceptuses as well as uterine endometrium collected from cyclic and pregnant gilts. Conceptus IL-1beta gene expression was enhanced during the period of rapid trophoblastic elongation compared with earlier spherical conceptuses, followed by a dramatic decrease in elongated Day 15 conceptuses. IL-1RT1 and IL-1RAP gene expression was greater in Day 12 and 15 filamentous conceptuses compared with earlier morphologies while IL-1Rant gene expression was unchanged by conceptus development. The uterine lumenal content of IL-1beta increased during the process of trophoblastic elongation on Day 12. Uterine IL-1beta content declined on Day 15, reaching a nadir by Day 18 of pregnancy. IL-1beta gene expression in porcine conceptuses was temporally associated with an increase in endometrial IL-1RT1 and IL-1RAP gene expression in pregnant gilts. Endometrial IL-1beta and IL-1Rant gene expression were lowest during Days 10-15 of the estrous cycle and pregnancy. The temporal expression of IL-1beta during conceptus development and the initiation of conceptus-uterine communication suggests conceptus IL-1beta synthesis plays an important role in porcine conceptus elongation and the establishment of pregnancy in the pig.     

Changes in ovine conceptus and endometrial function following asynchronous embryo transfer or administration of progesterone

The secretory protein profile from conceptuses collected from naturally mated ewes on Days 10, 12, 14, and 16 was characterized by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and fluorography. The presence of the anti-luteolysin ovine trophoblast protein-1 (oTP-1) in culture medium from Day 10 conceptuses was confirmed by fluorography, Western blotting, and radioimmunoassay (RIA). On each of the days studied, oTP-1 was the dominant secretory protein, and was secreted in increasing quantities as pregnancy progressed. In a second experiment, Day 6 embryos were transferred to either Day 6 (SR) or Day 4 (AR) recipients. Three mated ewes (P) received daily injections of 50 mg progesterone on Days 4-9. Controls consisted of 2 groups of pregnant ewes (D8 and D10). Conceptuses and ipsilateral endometrium were collected 4 days following transfer of conceptuses to SR and AR ewes, on Day 10 in P and D10 ewes, and on Day 8 in D8 ewes. Conceptus volume was estimated upon recovery from the uterus. Tissues were cultured with 35S-methionine, and the medium was analyzed for total and trichloroacetic acid-precipitable radiolabeled proteins. Levels of specific endometrial secretory proteins were determined after protein separation by 2D-PAGE and estimation of the radioactivity associated with discrete radiolabeled proteins on fluorographs. The concentration of oTP-1 in conceptus culture medium was estimated by RIA. Thirty endometrial proteins were investigated. All 30 proteins were present in endometrial cultures from SR, AR, D10, and P ewes, but 13 proteins were absent from D8 ewes. Levels of three proteins were higher in AR compared to D8 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Characterization of feline conceptus proteins during pregnancy

This study characterized proteins secreted de novo by feline conceptuses collected on Days 10, 12, and 15 (n = 22, preimplantation blastocysts); Days 15, 16, 17, 19, 21, and 25 (n = 6, postimplantation zonary girdle [ZG] i.e. trophoblast and endometrium); and Days 30, 36, 39, and 50 (n = 5, postimplantation ZG and free chorioallantois [CA]) and cultured in Minimal Essential Medium. De novo secretion was shown by incorporation of 3H-leucine into proteins detected in culture media by 2D-PAGE and fluorography. Western blotting, and NH2-terminal amino acid microsequencing. Major radiolabeled proteins identified as they appeared temporally on fluorographs were as follows: feline conceptus protein 1 (fCP1), Mr = 20,000, pI 5.0-5.3; fCP2, Mr = 80,000, pI 6.5-7.2; fCP3a, Mr = 67,000, pI 6.3-6.5; fCP3b, Mr = 67,000, pI 5.9-6.3; fCP4, Mr = 56,000, pI 5.0-6.0; and fCP5, Mr = 29,000, pI 5.0-5.8. The fCP1 was produced by blastocysts on Days 10-15, ZG on Days 16-25, and CA on Day 30; on Days 39-50, CA synthesized 5 proteins, possibly fCP1 isomers. The fCP2, fCP3a and b, and fCP4 were produced by blastocysts on Day 15, ZG on Day 25, and CA on Days 30-50. The fCP5 was made by ZG on Days 16-36 and by CA on Days 30-39. Western blotting identified fCP1 as retinol-binding protein (RBP), fCP2 as alpha fetoprotein, fCP3a as albumin, and fCP3b as transferrin. Amino acid sequence homologies between fCP1 and rabbit and human plasma RBP and porcine conceptus RBP2 were 93, 96, and 100%, respectively, at the first 37 NH2-terminal amino acids. The identities of fCP4 and fCP5 have not been established. Antiviral activity detected in all media was less than 3 units/ml when tested with feline fibroblast cells infected with vesicular stomatitis virus.     

Insulin-like growth factor-I expression during early conceptus development in the pig

Porcine conceptuses (embryo and associated membranes) in utero undergo developmental morphological transformations coincident with structural and biochemical changes in the uterine endometrium during early gestation. To elucidate a possible role for insulin-like growth factor-I (IGF-I) in these events, porcine endometrial (Days 8, 10, 11, 12, 14, and 30) and conceptus (Days 12, 14, and 16) tissues were characterized for the presence of IGF-I peptide and mRNAs. The corresponding uterine luminal fluids (ULF) at these stages of pregnancy were also analyzed for immunoreactive IGF-I concentration. ULF IGF-I was lowest on Day 8, highest on Day 12, and declined by Day 14. In contrast, endometrial tissue IGF-I content remained constant during this period. Conceptus tissues contained less IGF-I than endometrial tissues; however, conceptus IGF-I values were maximum on Day 12 coincident with peak values for ULF IGF-I. Dot-blot hybridization analyses revealed temporal variation in steady-state levels of IGF-I mRNAs in endometrium. Highest levels of endometrial IGF-I mRNA were detected on Day 12 and were about 4-fold greater than on Day 30 of pregnancy. IGF-I mRNA expression in conceptus tissues on Days 12, 14, and 16 was the same and was significantly less than that in endometrium on Day 12. These results demonstrate the temporal variation of IGF-I mRNA abundance in uterine endometrium and of immunoreactive IGF-I in ULF and in conceptus tissues, with the developmental processes occurring in the conceptuses at early pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Porcine conceptuses secrete an interferon during the preattachment period of early pregnancy

Maternal recognition of pregnancy in sheep and cattle is thought to be initiated by the conceptus secretory proteins ovine trophoblast protein-1 (oTP-1) and bovine trophoblast protein-1 (bTP-1), respectively. Recently, these proteins have been shown to be members of the interferon-alpha (IFN-alpha) family. In this study, we have examined whether pig conceptuses also produce IFN during early pregnancy. conceptuses were collected at Days 8, 10, 11, 12, 13, 15, and 17 of pregnancy and cultured in serum-free medium for 24 h. Day 11 conceptuses secreted a dominant 22,000-24,000 Mr cluster of acidic proteins (pI 5.2-5.4), that appeared to cross-react on immunoblots with antiserum against human IFN-alpha but not against oTP-1. Antiviral activity characteristic of an IFN was present in conceptus culture medium and uterine flushings from Day 11 through Day 17 of pregnancy, but was absent in flushings prior to Day 11 of pregnancy and in flushings from Day 12 nonpregnant gilts. The antiviral activity coeluted with a 22,000-24,000 Mr protein during partial purification through a gel filtration column. The activity was extremely labile, but could be restored by sequential protein denaturation, reduction, and renaturation. We conclude that production of IFN by early conceptuses is not restricted to ruminant species, and may therefore represent a more general phenomenon.     

The retinol-binding protein of the expanding pig blastocyst: molecular cloning and expression in trophectoderm and embryonic disc.

Retinol-binding protein (RBP) is a major secretory product of the porcine conceptus. Using an oligonucleotide probe corresponding to a highly conserved region of all known mammalian RBP, we have isolated an apparently full-length cDNA clone for porcine conceptus RBP from a cDNA library constructed from pig conceptuses collected between days 13-17 of pregnancy. The cDNA was 937 base-pairs in length and coded for a protein whose inferred amino-terminal sequence was identical to that reported for both porcine conceptus RBP and porcine serum RBP. Its length was consistent with the size (approximately 1 kilobase) of the RBP message in porcine conceptuses. Porcine conceptus RBP and human serum RBP share 91% amino acid sequence identity. The inferred differences in sequence were evenly distributed throughout the length of the polypeptide. RBP mRNA was detectable within the trophoblast of day 11 porcine conceptuses by in situ hybridization with a 618-basepair 35S-labeled probe corresponding to the 3' end of porcine RBP. Silver grain density was distributed relatively uniformly over the trophoblast and the inner cell mass. Western blot analysis of conceptus culture medium demonstrated that the conceptuses of cattle (on day 19) and sheep (on day 15) as well as pigs secrete RBP during early pregnancy. Secretion of large quantities of RBP by the trophoblast of preimplantation pig conceptuses suggests important roles for vitamin A and RBP near the time of conceptus elongation.     

Endometrial surface and secretory alterations associated with embryonic mortality in gilts administered estradiol valerate on days 9 and 10 of gestation

Administration of estrogen to gilts on Days 9 and 10 of pregnancy results in total embryonic loss by Day 18. The present study examined changes in the uterine endometrial surface and secretion during conceptus attachment in control and estrogen-treated (Days 9 and 10) pregnant gilts. Gilts were unilaterally hysterectomized on either Days 12 and 14 or Days 16 and 18 of gestation. Uterine horns were flushed with saline and conceptuses were evaluated. Intact conceptuses were recovered from all control gilts, whereas estrogen-treated gilts contained normal intact conceptuses only on Day 12 of gestation. Antiviral activity, which reflects conceptus viability, was reduced (p less than 0.01) in uterine flushings after Day 14 in estrogen-treated gilts. Culture of endometrial explants with [3H]glucosamine revealed several glycoproteins that are synthesized during the period of conceptus attachment; however, no difference in glycoprotein synthesis between treatment groups was detected by analysis with two-dimensional PAGE and fluorography. Analyses of the uterine epithelium by scanning and transmission electron microscopy demonstrated that estrogen administration caused an alteration in the uterine surface, a thinning of the uterine epithelial glycocalyx, and a reduction of cationic ferritin binding to the microvilli of the uterine epithelium. Results indicate that conceptus mortality after early administration of estrogen is associated with alterations in the uterine endometrial surface during the period of conceptus attachment in the pig.     

Evidence for maternal regulation of early conceptus growth and development in beef cattle

Fifty-one cyclic beef cows were mated with fertile bulls. At 36 h after the start of oestrus, cows were assigned to receive sesame oil (controls) or progesterone (100 mg) on Days 1, 2, 3 and 4 of pregnancy. Peripheral plasma concentration of progesterone was measured until slaughter on Days 5 or 14. Cows were randomly assigned to be slaughtered on Days 5 or 14 or remain intact and palpated per rectum on Day 40 to verify pregnancy. Uteri on Days 5 and 14 were flushed for recovery of luminal protein and conceptus tissue. Conceptus and endometrial tissues were cultured with [3H]leucine and submitted to two-dimensional-PAGE and fluorography. Administration of progesterone increased peripheral plasma progesterone concentration on Day 2-5. Conceptuses recovered from progesterone-treated cows on Day 14 were advanced in development compared to conceptuses from control cows. Conceptuses recovered from progesterone-treated cows were viable as polypeptides associated with maintenance of pregnancy in cattle were synthesized and released at an earlier time and pregnancy was maintained beyond Day 40. Early progesterone stimulation altered the synthesis and release of polypeptides from endometrial explant cultures on Day 5. Results indicate a role of progesterone in the maternal regulation of conceptus growth and development in early pregnancy of cattle.     

Endometrial glands are required for preimplantation conceptus elongation and survival

Endometrial glands secrete molecules hypothesized to support conceptus growth and development. In sheep, endometrial gland morphogenesis occurs postnatally and can be epigenetically ablated by neonatal progestin exposure. The resulting stable adult uterine gland knockout (UGKO) phenotype was used here to test the hypothesis that endometrial glands are required for successful pregnancy. Mature UGKO ewes were bred repeatedly to fertile rams, but no pregnancies were detected by ultrasound on Day 25. Day 7 blastocysts from normal superovulated ewes were then transferred synchronously into Day 7 control or UGKO ewes. Ultrasonography on Days 25-65 postmating indicated that pregnancy was established in control, but not in UGKO ewes. To examine early uterine-embryo interactions, four control and eight UGKO ewes were bred to fertile rams. On Day 14, their uteri were flushed. The uterus of each control ewe contained two filamentous conceptuses of normal length. Uteri from four UGKO ewes contained no conceptus. Uteri of three UGKO ewes contained a single severely growth-retarded tubular conceptus, whereas the remaining ewe contained a single filamentous conceptus. Histological analyses of these uteri revealed that endometrial gland density was directly related to conceptus survival and developmental state. Day 14 UGKO uteri that were devoid of endometrial glands did not support normal conceptus development and contained either no conceptuses or growth-retarded tubular conceptuses. The Day 14 UGKO uterus with moderate gland development contained a filamentous conceptus. Collectively, these results demonstrate that endometrial glands and, by inference, their secretions are required for periimplantation conceptus survival and development.     

Swine leukocyte antigen-DQ expression and its regulation by interferon-gamma at the maternal-fetal interface in pigs

Successful pregnancy requires an appropriate intrauterine immune response to the conceptus, which is a semiallograft within the uterus. We reported that swine leukocyte antigen-DQA (SLA-DQA), a major histocompatibility complex (MHC) class II gene, is expressed in the uterine endometrium at the time of conceptus implantation in pigs. Because MHC molecules play critical roles in the immune system, SLA-DQ was hypothesized to be involved in immune regulation during pregnancy. Therefore, we examined expression of SLA-DQ in uterine endometrial tissues obtained during the estrous cycle and pregnancy. SLA-DQA and SLA-DQB mRNAs were detected as 1.3-kb and 1.2-kb bands, respectively. Real-time RT-PCR analysis indicated that SLA-DQA and SLA-DQB mRNA expression was affected by day and pregnancy status, with the highest expression on Day 15 of pregnancy. SLA-DQ was localized primarily to subepithelial stromal cells and endothelial cells of the uterus. Using endometrial explant cultures from Day 12 of the estrous cycle, we determined that expression of SLA-DQA and SLA-DQB mRNAs increased in response to interferon-gamma (IFNG), which is produced by pig conceptus trophectoderm between Days 14 and 18 of pregnancy. The abundance of SLA-DQ protein was less in endometria from gilts with conceptuses resulting from somatic cell nuclear transfer compared with endometria from gilts with conceptuses resulting from natural mating. These results support our hypothesis that SLA-DQ is expressed in response to IFNG from the conceptus, and likely regulates immune response at the maternal-fetal interface to support the maintenance of pregnancy in pigs.     

Steroid metabolism by endometrial and conceptus tissues during early pregnancy and pseudopregnancy in gilts

Endometrial and conceptus tissues were obtained on Days 10.5, 11, 12, 16 and 25 of pregnancy and Day 25 of pseudopregnancy of gilts and incubated for 6 h in Minimal Essential Medium (5 ml) containing 35 ng [3H]progesterone. Metabolism of [3H]progesterone to oestrone, oestradiol and oestriol was determined by gas and high-pressure liquid chromatography and successive recrystallizations with unlabelled standards. Conceptuses collected between Days 10.5 and 12 were spherical, tubular or filamentous and incubated with 500 mg endometrium and [3H]progesterone. Production of oestrone by spherical conceptuses was not detected, but was 44-47 pg/tubular conceptus and 21 pg/filamentous conceptus. A similar trend was observed for oestradiol. Conceptus tissues from Days 16 and 25 (chorion) were most active in producing oestrone (123 and 520 pg/mg tissue, respectively) and oestradiol (277 and 876 pg/mg tissue, respectively). Endometrial oestrogen production was less than that for conceptus tissue for oestrone and oestradiol on Days 16 and 25 of gestation. Coincubations of endometrium and conceptus tissues had lower oestrogen production than conceptus alone. Endometrium from Day 25 of pseudopregnancy metabolized [3H]progesterone to several non-polar metabolites, but no oestrogens were detected. An unidentified phenolic metabolite of [3H]progesterone was detected in higher quantities than either oestrone or oestradiol; 445 to 461 pg/conceptus at the tubular stage. These results indicate temporal changes in the conversion of [3H]progesterone to oestrogens by conceptus and endometrial tissue from pregnant gilts, but not endometrium from pseudopregnant gilts.     

Characterization of the uterine environment during early conceptus expansion in the bovine

Fifty-three Angus and Hereford beef cows were utilized to investigate the effect of the conceptus on uterine environment during the period of pregnancy recognition. Blood samples were collected on Days 10, 12, 14, 16 and 18. Cows were randomly assigned to be either mated on the subsequent oestrus or serve as cyclic controls. Blood samples were then collected daily from Day 10 until slaughter on Day 15, 16 or 17 from the initiation of oestrus. Uteri were flushed with physiological saline and flushings analyzed for quantitative and qualitative protein changes, calcium, oestradiol-17β and prostaglandin F content. Endometrial explants of caruncular and intercaruncular tissue, and conceptus tissue recovered from pregnant cows were cultured with [³H]-leucine to determine quantitative and qualitative polypeptide synthesis and release. Plasma progesterone concentrations were similar between pregnant and cyclic cows from Day 10 through 17. Only the uterine content of prostaglandin F significantly increased in the ipsilateral horn of pregnant cows on Days 16 and 17. This increase in prostaglandin content was related to the increase in conceptus length from 25 to 40–80 mm. Conceptus production of bovine trophoblastic protein-1 was also first clearly detectable in fluorographs of medium from conceptuses measuring 25 mm. The complexity of the polypeptides present in the medium increased with conceptus development. Polypeptide synthesis by the endometrium was similar between tissues and days; however, production of two groups of low molecular weight basic polypeptides continued to be intensified on fluorographs from the pregnant horn on Day 17 compared to cyclic cows.     

Effect of heat stress on conceptus and uterine secretion in the bovine

This study examined the effects of heat stress on conceptus secretion of bovine trophoblastic proteins (bTP) and the uterine secretory environment on Day 17 of pregnancy. After mating to fertile bulls, cows were placed in an environmental chamber at 21 degrees C, 45% RH on Day 7 and were assigned to one of the following treatments on Day 8: Control (21 degrees C, 45% RH), Treatment 1 (37 degrees C, 30% RH) and Treatment 2 (37 degrees C, 40% RH). Cows were slaughtered on Day 17 and each uterine horn was flushed separately with physiological saline to recover the conceptus and uterine contents. The wet weight of the conceptus was recorded and uterine flushings were analyzed for quantitative and qualitative protein changes, prostaglandin F and calcium concentrations. Conceptus tissue was cultured in vitro with 100 muCi of [(3)H]-leucine and the polypeptides released into the medium were analyzed by 2D-PAGE followed by fluorography. Heat stress increased rectal temperature of cows and reduced conceptus wet weight. Uterine content of protein and calcium were increased in the uterine horn ipsilateral to the CL of heat-stressed cows. Although uterine protein increased in heat-stressed cows, no qualitative difference was observed in the polypeptides present in the uterine lumen. Conceptus synthesis and release of bTP were enhanced in treated cows. These responses indicate that heat stress between Days 8 to 17 of pregnancy altered the uterine environment as well as growth and secretory activity of the conceptus.     

Influence of the endometrium, protease inhibitors and freezing on antiviral activity of proteins secreted by pig conceptuses

In Exp. 1, only medium from cultures containing conceptus tissue had antiviral activity (P less than 0.05). Addition of Day-15 pregnant endometrium or Day-14 cyclic uterine flush proteins to cultures containing 200 mg conceptus tissue decreased antiviral activity (conceptus x endometrial protein interaction, P less than 0.06). Effects of endometrium (-54%) and uterine flush proteins (-40%) on antiviral activity of conceptus cultures did not differ from each other (P greater than 0.10). In Exp. 2, antiviral activity was only detected in cultures containing conceptus tissue (P less than 0.06). The amount of antiviral activity in cultures of Day-15 conceptus tissue was not influenced differently (P greater than 0.10) by culture in medium conditioned by endometrium from Day 10 or Day 12 of pregnancy. However, antiviral activity was undetectable in medium conditioned by endometrium from one of the Day-12 gilts. In Exp. 3, antiviral activity was present in medium from only 1 of 3 cultures from Day-12 gilts when assayed unfrozen. Antiviral activity was lower (P less than 0.01) in cultures of conceptuses from Day 12 than Day 14 of pregnancy; however, antiviral activity increased quadratically (P less than 0.05) when cultures contained 0, 0.01, 0.1 and 1.0 units/ml aprotinin, respectively. Freezing and thawing culture medium did not reduce (P greater than 0.10) antiviral activity compared to medium assayed unfrozen (1438 vs 1354 units/ml, respectively). These results suggest a regulatory influence of the endometrium on secretion of antiviral proteins by pig conceptuses in vitro.     

Pattern of medium proteins radiolabelled after culture of Day 13 to 16 pig conceptus tissue with [3H]leucine and absence of chorionic gonadotrophin-like activity

Day 13-16 pig conceptus tissue was cultured for 24 h in medium containing [3H]leucine. The patterns of radioactively labelled proteins that were released into the medium during culture were analysed by SDS-polyacrylamide gel electrophoresis and fluorography. Day-13 conceptuses released two major radiolabelled proteins of Mr 23 000 and 26 000 and Day 14-16 conceptuses released these as well as proteins of Mr 14 000, 19 000, 44 000, 50 000 and 88 000. Various immunological and biological tests for a human chorionic gonadotrophin-like activity were performed on tissue extracts and on culture medium, but there was no evidence for its presence in the pig conceptus at Day 13-16 of gestation.     

Maternal recognition of pregnancy in the rabbit

Conceptuses were removed by extrusion through incisions in the uterus on Days 11, 12 and 18 post coitum (p.c.). Pseudopregnant does at Days 11 and 12 and pregnant does at Day 18 were sham-operated and served as controls. Blood samples were collected before and daily for 3 days after conceptus removal. Serum progesterone profiles of does whose conceptuses were removed on Day 11 p.c. were identical to those of intact pseudopregnant and sham-operated pseudopregnant controls. Conceptus removal on Days 12 or 18 p.c. resulted in a precipitous decline (P less than 0 X 01) in progesterone levels within 48 h. LH levels were low (less than 1 ng/ml) in all groups before and after surgery and there were no significant differences between treated and control rabbits. These data demonstrate that the maternal recognition of pregnancy occurs by Day 12 of gestation and that conceptus removal does not result in an alteration in serum LH levels.     

Maternal recognition of pregnancy in the goat: effects of conceptus removal on interestrus intervals and characterization of conceptus protein production during early pregnancy

Goat conceptuses were surgically removed from the uterus at different days during early pregnancy and cultured for 24-30 h in the presence of L-[3H]leucine to determine the effects of embryo removal on the interestrus interval and to characterize in vitro synthesis and release of conceptus proteins. Normal cyclic and animals (controls) exhibited interestrus intervals of 20.44 +/- 0.89 days. Removal of conceptuses on Days 13 and 15 did not alter interestrus intervals compared to cyclic animals. Removal of conceptuses on Day 17 and times thereafter resulted in significant (p less than 0.05) prolongation of interestrus intervals. These results demonstrate that maternal recognition of pregnancy in the goat occurs between Days 15 and 17. Proteins synthesized and released into the medium by conceptuses were first detectable at Day 16 by the analytical method employed (two-dimensional polyacrylamide gel electrophoresis followed by fluorography). The major protein synthesized at this time was acidic (pI = 5.2-5.7) and consisted of two isotypes with molecular weights of about 17,000. Although patterns of protein production became more complex with conceptus development, this protein remained as a major product through Day 21 but not afterwards. This protein, as well as two other low molecular weight acidic proteins (Mr approximately equal to 21,000, 23,000; pI = 5.7-6.0) were shown by immunoprecipitation to react with anti-ovine trophoblast protein-1 (oTP-1) serum. Hence, these products may comprise a caprine trophoblast protein-1 (cTP-1) complex.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regulation of expression and role of leukemia inhibitory factor and interleukin-6 in the uterus of early pregnant pigs

Cytokines, which are generally involved in the process of inflammation, may also play a critical role in conceptus implantation. We examined: (1) the expression profiles of leukemia inhibitory factor (LIF) and interleukin (IL)-6 mRNA and their protein content in the endometrium of cyclic and pregnant gilts on Days 10 to 18 after estrus; (2) the effect of conceptus-exposed medium on LIF and IL-6 synthesis in the endometrium; (3) the profiles of IL6R and LIFR mRNA expression in pig conceptuses collected on Days 10 to 18 of pregnancy; and (4) the effect of LIF and IL-6 on the attachment and proliferation of porcine trophoblast cells. The expression of LIF mRNA in the endometrium increased between Days 10 and 12 in both cyclic and pregnant gilts, and tended to be higher in Day 12 pregnant animals compared with nonpregnant ones. The LIF protein content in the uterine lumen peaked on Day 12 of pregnancy, and was higher than on Day 12 of the estrous cycle. Endometrial IL-6 mRNA expression was upregulated on Day 12 in pregnant gilts compared with nonpregnant animals. Moreover, a higher content of IL-6 protein was observed in pregnant than in cyclic gilts. The addition of conceptus-exposed medium resulted in up-regulation of LIF and IL6 mRNA expression, and increased IL-6 content in endometrial slices. In conceptuses, increased mRNA expression was detected on Days 10 to 14 for IL6R and on Day 14 for LIFR, when compared with other days studied. LIF and IL-6 stimulated the attachment and proliferation of trophoblast cells in vitro. In summary, LIF and IL-6 are important components of embryo-uterine interactions during early pregnancy in the pig, and may contribute to successful conceptus implantation.     

Inhibitory effects of adrenocorticotrophin or corticosterone on progesterone secretion during mid-pregnancy in rats

Conceptus number was reduced to one on Day 7 of pregnancy in rats by aspirating all but a single conceptus (Group E) or left at greater than or equal to 8 conceptuses (Group C). In Group E rats, serum progesterone concentrations remained low from Day 12 until autopsy at Day 21. Hypophysectomy on Day 12 significantly increased serum progesterone values after Day 17 of pregnancy, and these increases were blocked by treatment with ACTH (10 U/day, i.p., Days 12-17). Adrenalectomy on Day 12 also induced slight, but statistically significant, increases in serum progesterone concentration after Day 17, and these were overcome by implantation of a 10 mg capsule of corticosterone. In Group C rats, hypophysectomy or adrenalectomy on Day 12 did not change serum progesterone concentrations, but 40 U ACTH/day inhibited progesterone secretion. We conclude from these results that the pituitary-adrenal system exerts inhibitory effects on progesterone secretion during mid-pregnancy in rats.