Biomedical subjects

F W Bazer

Publications and source records attributed to F W Bazer.

At least 181 records · Page 10Linked to original sources

PubMed1989

Effects of pregnancy, oxytocin, ovine trophoblast protein-1 and their interactions on endometrial production of prostaglandin F2 alpha in vitro in perifusion chambers.

Pregnancy and intrauterine infusion of ovine trophoblast protein one (oTP-1) decrease oxytocin-induced secretion of prostaglandin F2 alpha (PGF) from the uterus. In the present study, effects of oTP-1 and pregnancy on endometrial secretion of PGF were examined in an in vitro perifusion system. In Experiment 1, endometrium from day 14 pregnant and cyclic ewes was perifused sequentially on both the lumenal and myometrial sides with Krebs Ringers Bicorbonate solution (KRB), KRB plus oxytocin (1 IU/ml) and KRB alone. Endometrium from pregnant ewes secreted more PGF from both lumenal and myometrial sides than endometrium from cyclic ewes (P less than 0.05). Oxytocin stimulated secretion of PGF from both sides of endometrium regardless of status. Secretion of PGF was greater from the lumenal surface of endometrium compared to myometrium (P less than 0.05) for pregnant and cyclic ewes. For Experiment 2, endometrium was collected from day 15 cyclic ewes and perifused sequentially with KRB, KRB plus 300 ng/ml of either Bovine Serum Albumin (BSA) or oTP-1, KRB with or without BSA or oTP-1 plus oxytocin (1 IU/ml) and then KRB alone. Oxytocin stimulated greater release of PGF from oTP-1-treated than BSA-treated endometrium. Pretreatment of endometrium with oTP-1 had the same effect on oxytocin-induced PGF secretion as cotreatment with oTP-1 and oxytocin. In Experiment 3, uterine horns of cyclic ewes were catheterized on day 10 of the estrous cycle, and infused with either oTP-1 or day 16 pregnant sheep serum proteins on days 12, 13 and 14. Endometrium was collected on day 15 and perifused sequentially with KRB, KRB plus oxytocin (1 IU/ml) and then KRB alone. Treatment of ewes with oTP-1 attenuated endometrial secretion of PGF in response to oxytocin. Results of this study indicate that: (1) pregnancy stimulates basal secretion of PGF from endometrium and has no effect on oxytocin-induced secretion of PGF in vitro; (2) short-term oTP-1 treatment enhances oxytocin-induced PGF secretion from day 15 cyclic endometrium and (3) long-term oTP-1 treatment in vivo inhibits oxytocin-induced PGF secretion in ewes.

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PubMed1989

Porcine endometrial prolactin receptors detected by homologous radioreceptor assay.

Heterologous radioreceptor assays, commonly using ovine prolactin, may generate inconsistent results since prolactin (PRL) from one species may be recognized as growth hormone in another. Homologous radioreceptor assays (RRA) are most similar to the in vivo hormone-tissue receptor environment; however, lactogenic homologous RRAs have been reported only for mouse hepatic membranes. In this study, an assay system was developed to investigate homologous binding for porcine PRL in porcine uterine tissue. The pig does not produce a decidual PRL or a placental lactogen; yet, PRL affects uterine physiology during reproductively important events. Optimal binding conditions established for porcine PRL homologous RRA include 150 micrograms membrane, 45,000 cpm labeled porcine PRL and 500 microliters sodium phosphate buffer pH 7.6, incubated at 25 degrees C for 24 h. Binding of porcine PRL tracer is very low (less than 3%); however, when tissue is treated with the chaotropic agent, MgCl2 (4 M), binding increases from 3 to 28%. Dissociation kinetics show a rate of 3.79 X 10(-6)/s initially, and then 1.63 X 10(-6)/s. Competition for labeled PRL on binding sites with unlabeled porcine PRL results in 80% displacement with unlabeled porcine prolactin (NSB) of 7% at 1000 ng. Affinity constant generated from homologous inhibition assays is 0.326 X 10(8) M-1. Porcine growth hormone (GH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) do not displace porcine PRL tracer. These data describe a lactogenic homologous RRA for porcine endometrial membranes similar to that previously reported for murine hepatic tissue. Homologous RRAs may allow elucidation of PRL receptor characteristics with more similarity to the in vivo hormone-receptor milieu.

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PubMed1989

Secretion of the major progesterone-induced proteins of the sheep uterus by caruncular and intercaruncular endometrium of the pregnant ewe from days 20-140 of gestation.

An experiment was performed to evaluate the types and quantity of proteins secreted by intercaruncular endometrium at days 20, 60, 100 and 140 of gestation and caruncular endometrium from days 100 and 140 of gestation. Tissues were obtained from ewes made unilaterally pregnant. Based on SDS polyacrylamide gel electrophoresis (SDS-PAGE), the major proteins present in uterine fluid at days 60-140 of gestation were the uterine milk proteins (UTM-proteins), a pair of structurally-related, progesterone-induced polypeptides with molecular weights of 55,000 and 57,000. These proteins were also present in uterine fluid at day 20, but the major protein at this time migrated coincident with albumin. Cultured explants of endometrium at all days of pregnancy produced UTM-proteins as their major radiolabelled product for both caruncular and intercaruncular endometrium. The amount of protein secretion in vitro was greater (P less than .04) for intercaruncular endometrium than for caruncular endometrium but was not significantly affected by stage of gestation or local presence of the conceptus. Immunohistochemical analysis revealed that UTM-proteins were present in glandular and luminal epithelium of intercaruncular endometrium and in both epithelial and stromal elements of caruncular endometrium. It was concluded that the UTM-proteins are produced earlier than previously described (i.e., day 20). In addition, caruncles contribute to the uterine secretory protein milieu through the secretion of proteins that are similar to that produced by the glandular intercaruncular epithelium.

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PubMed1989

Establishment of pregnancy in sheep and pigs.

Sheep conceptuses secrete a protein, ovine trophoblast protein-1 (oTP-1), between days 10 and 21 of gestation, that is responsible for establishment of pregnancy. oTP-1 inhibits uterine production of episodic release of prostaglandin (PG) F2 alpha (PGF) necessary for luteolysis and produced in response to oestradiol and oxytocin. oTP-1 does not compete with oxytocin for binding to its receptors or interfere with oxytocin stimulation of the inositol phospholipid second messenger system after oxytocin receptors are formed. However, oTP-1 may affect synthesis of oxytocin, oestrogen and/or progesterone receptors to alter the ability of the uterus to produce episodic pulses of PGF in response to episodic pulses of oxytocin. Porcine conceptuses secrete oestrogens between days 10 and 15 of pregnancy that are essential for establishment of pregnancy. Oestrogens, directly or indirectly, alter secretion of PGF from an endocrine direction (toward the uterine vasculature) to an exocrine direction (toward the uterine lumen). PGF sequestered in the uterine lumen is unavailable to exert a luteolytic effect on the corpus luteum (CL). Pig conceptus secretory proteins stimulate uterine production of PGF and PGE, but do not appear to be responsible for inhibition of luteolysis. Conceptus secretory proteins of sheep and pigs include proteins that have antiviral activity and are considered interferons. In sheep, oTP-1 has antiluteolytic, immunosuppressive, antiviral and possibly antiproliferative properties. The specific pig conceptus secretory protein(s) possessing antiviral activity has not been established. Unlike oTP-1, however, pig interferon-like protein(s) does not appear to possess antiluteolytic activity.

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PubMed1989

Presence of the major progesterone-induced proteins of the sheep endometrium in fetal fluids.

Allantoic and amniotic fluids were collected on Days 60 (n = 3), 100 (n = 4), and 140 (n = 3) of pregnancy. The presence of uterine milk proteins (UTM-proteins) in these samples was evaluated by Ouchterlony immunodiffusion and enzyme-linked immunoabsorbant assay (ELISA). Eight of ten samples of allantoic fluid and three of ten samples of amniotic fluid produced one or two immunoprecipitin bands against antiserum to UTM-proteins. Each band fused with immunoprecipitin bands from UTM-proteins purified from uterine fluid. Data from a semi-quantitative ELISA indicated that allantoic fluid from all ewes and amniotic fluid from six of ten ewes contained immunoreactive UTM-proteins. Concentrations of UTM-proteins in these fluids were not statistically affected by day of gestation (p greater than 0.10), but tended to decline as gestation advanced. Greater concentrations of UTM-proteins were detected in allantoic fluid than in amniotic fluid (p less than 0.05). The physical characteristics of the immunoreactive material in allantoic and amniotic fluids were examined by polyacrylamide gel electrophoresis and Western blotting. The immunoreactive material was found to possess pIs and molecular weights identical to UTM-proteins. These results indicate that fetal fluids contain material that reacts with antiserum to UTM-proteins and has physical properties similar to UTM-proteins. It is likely, therefore, that the UTM-proteins are transported across the placenta during gestation, perhaps to serve some function in the fetal compartment.

Allantois↗

PubMed1989

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)

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PubMed1989

Effect of porcine conceptus secretory proteins on interestrous interval and uterine secretion of prostaglandins.

Porcine conceptus secretory proteins (pCSP) were obtained from medium in which pig conceptuses, collected on Day 15 of pregnancy, were cultured for 30 h. Culture medium was pooled, dialyzed, and concentrated by Amicon ultrafiltration for intrauterine infusion. Serum proteins (SP) were obtained from blood collected from a Day 15 pregnant gilt and diluted for intrauterine infusion. Catheters were placed into both uterine horns and the inferior vena cava of cyclic (Day 8) gilts. Single blood samples were collected at 0800 h on Days 9, 10, and 11. On Day 11, all gilts received 1 mg estradiol-17 beta (E2) i.m. at 0800 h. Protein infusions commenced on Day 12 and continued through Day 15, twice daily at 0800 h and 2000 h. Protein infusions per uterine horn were (1) 4.0 mg pCSP + 4.0 mg SP (pCSP, 4 gilts) and (2) 8.0 mg SP (SP, 4 gilts). Blood samples were collected every 15 min on Days 12 through 17 between 0805 h and 1100 h. Single blood samples were collected at 0800 h after Day 17 until gilts exhibited estrus. Concentrations of prostaglandin (PG) E, 13,14-dihydro-15-keto-PGF2 alpha (PGFM), and progesterone (P4) were measured by specific radioimmunoassays. Interestrous intervals for pCSP-treated (18.2 days) and SP-treated (18.0 days) gilts were not different (SEM = 0.8 days) and temporal changes in concentrations of P4 in plasma did not differ between pCSP-treated (29.2 ng/ml) and SP-treated (31.2 ng/ml) gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

High molecular weight basic and acidic immunosuppressive protein components in uterine secretions of pregnant cows.

Immunosuppressive proteinaceous components were determined in bovine uterine milk (UTM) collected during late pregnancy. Crude UTM was separated by ion-exchange (carboxymethylcellulose-CMC) and gel filtration (Sephacryl S-200 and Sepharose CL-6B) chromatography. Basic (CMC+) and acidic (CMC-) protein molecular weight (Mr) components were tested for immunosuppressive activity in an in vitro mitogen (phytohemagglutinin-PHA)-treated lymphocyte blastogenesis assay. For most experiments, cultures containing 1 x 10(5) lymphocytes were incubated with 0.08 micrograms PHA and varying concentrations of test protein in RPMI-1640 with supplements. At 48 +/- 1 h, 0.1 microCi of [3H]thymidine was added to cultures and [3H]DNA was quantified at 60 +/- 1 h of culture. Results were expressed as percentage of control values. Crude UTM, CMC+, and CMC- components exhibited immunosuppressive activity. For immunosuppressive Sephacryl S-200 fractions, activity was greater (p less than 0.05-0.01) for CMC+, S-200 fraction I (greater than or equal to 250,000 Mr, void volume [Vo]) than for CMC-, S-200 fractions I (Vo) and III combined for protein concentrations of 20, 40, and 50 micrograms/ml. For the high Mr Sepharose CL-6B protein components, CMC+, CL-6B fraction I (greater than or equal to 4 x 10(6) Mr, Vo) exhibited greater (p less than 0.05-0.005) activity than CMC-, CL-6B fractions I (greater than or equal to 4 x 10(6) Mr, Vo) and II (2.8 x 10(6) Mr) combined at protein concentrations ranging from 20 to 80 micrograms/ml. In summary, bovine UTM contains basic and acidic immunosuppressive protein components, with the greatest activity being associated with a high Mr, basic component.

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PubMed1989

Inhibition of lymphocyte proliferation by uterine fluid from the pregnant ewe.

Immunosuppressive molecules in uterine fluid from the nonpregnant uterine horn of unilaterally pregnant ewes at Days 60, 100, and 140 of gestation were examined. Uterine fluid from all days inhibited [3H]thymidine incorporation into phytohemagglutinin-stimulated lymphocytes. Inhibitory activity increased with advancing gestation. Uterine fluid also inhibited lymphocyte proliferation caused by other mitogens or by mixed lymphocyte reactions. Inhibitory activity was found in both salt volume (Mr less than 1000) and void volume (Mr greater than 5000) fractions of uterine fluid resolved by Sephadex G-25 desalting columns. Only activity in the void volume was sensitive to pronase. Several fractions containing inhibitory activity were resolved when dialyzed uterine fluid was fractionated into acidic and basic components by cation-exchange chromatography and further resolved by gel filtration using Sepharose CL-6B. The most active fractions (inhibition/micrograms protein) for both acidic and basic components eluted at the void volume of Sepharose CL-6B (Mr greater than 4 x 10(6). The inhibitory factor in the basic component that eluted at the void volume of Sepharose CL-6B was rich in carbohydrate, slightly cytotoxic, and partially sensitive to digestion with trypsin or oxidation with periodate. In conclusion, uterine fluid of unilaterally pregnant ewes is enriched in molecules that inhibit lymphocyte proliferation in vitro. Among these are low molecular weight, non proteinaceous factors and a very high molecular weight (Mr greater than 4 x 10(6) fraction that contains protein and carbohydrate.

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PubMed1989

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)

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PubMed1989

Inhibition of lymphocyte proliferation by ovine trophoblast protein-1 and a high molecular weight glycoprotein produced by the peri-implantation sheep conceptus.

Sheep conceptuses were flushed from uteri on day 16 of pregnancy and cultured in vitro. Three peaks of immunosuppressive activity (i.e., ability to inhibit [3H]thymidine incorporation into mitogen-stimulated lymphocytes) were localized in conceptus-conditioned culture medium: one corresponding to a high-molecular-weight glycoprotein (HMWG; Mr = 800-900 kDa), one corresponding to ovine trophoblast protein-1 (oTP-1), the antiluteolytic, interferon-like molecule of the sheep conceptus, and a third fraction containing a previously undescribed molecule with a molecular weight between 10 and 14 kDa. Both HMWG and oTP-1 inhibited lymphocyte proliferation in a dose-dependent manner. Delaying the addition of HMWG or oTP-1 until 24 h after the addition of phytohemagglutinin (PHA) reduced the degree of suppression relative to cultures where HMWG and oTP-1 were added at the time of PHA addition. Nonetheless, the molecules were still capable of inhibiting proliferation. Addition of human recombinant IL-2 (0-65 U/ml) to PHA-stimulated lymphocyte cultures could not reverse HMWG- or oTP-1-induced suppression of [3H]thymidine uptake by PHA-stimulated cells. Furthermore, treatment of lymphocytes with HMWG or oTP-1 suppressed IL-2-induced proliferation. Therefore, HMWG and oTP-1 affect both early and later events in the in vitro proliferative response of mitogen-stimulated lymphocytes, including responsiveness to IL-2.

Animals↗

PubMed1989

Effect of in-vitro heat stress on prostaglandin and protein secretion by endometrium from pregnant and cyclic gilts at day 14 after oestrus.

Endometrium from cyclic (N = 4) and pregnant (N = 4) gilts at Day 14 after oestrus was placed into three bilateral perifusion devices which allow separate perifusion of luminal and myometrial sides. Perifused endometrium was subjected to 39 or 42 degrees C. Incorporation of [3H]leucine into secreted and tissue proteins by endometrial explants following incubation at 39 or 42 degrees C was examined using trichloroacetic acid (TCA) precipitation and one-dimensional SDS polyacrylamide gel electrophoresis. Secretion of PGF was greater from the myometrial side for cyclic gilts (endocrine orientation), but greater from the luminal side for pregnant gilts (exocrine orientation). Regardless of reproductive status or endometrial side, heat stress induced a rapid increase (P less than 0.01) in PGF secretion rates. However, PGF secretion in response to heat stress was greater (P less than 0.01) from the myometrial side and greater (P less than 0.01) for pregnant gilts. PGF secretion rates increased by 63% and 42% from the luminal side, and 40% and 156% from the myometrial side in response to heat stress for cyclic and pregnant gilts, respectively (status x treatment x side interaction; P less than 0.01). Heat stress did not alter incorporation of [3H]leucine into secreted proteins regardless of reproductive status, while incorporation into tissue proteins was decreased (P less than 0.05) by heat stress for pregnant gilts, but not altered for cyclic gilts. Heat stress, in vitro, redirects PGF secretion for endometria of pregnant gilts from an exocrine to an endocrine orientation where it would be available to effect luteolysis and compromise the establishment of pregnancy.

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PubMed1989

Effects of prolactin on conceptus survival and uterine secretory activity in pigs.

Hypoprolactinaemia was induced by bromocriptine (CB154; 100 mg/day) which decreased circulating prolactin by 40% (P less than 0.06), but did not affect conceptus survival at Day 25 when administered on Days 10-16 when compared to saline:ethanol-treated control gilts. Bromocriptine or vehicle was administered to cyclic gilts on Days 10-11, oestradiol valerate was injected on Day 11 and uterine flushings were collected on Day 12. Total recoverable protein and uteroferrin in uterine flushings were not affected by treatment. However, leucine aminopeptidase activity (P less than 0.02) and total recoverable Ca2+, Na+, K+ and Cl- (P less than 0.05) were decreased in uterine flushings of gilts that received bromocriptine, suggesting that hypoprolactinaemia decreased general secretory activity of the endometrial epithelium and modulated ionic changes, respectively, in the uterine environment of pigs. Subcutaneous administration of pig prolactin (1 mg/12 h) increased (P less than 0.001) serum prolactin 4.5-fold. The interaction between hyperprolactinaemia and progesterone, without oestrogen, on components of uterine flushings were determined using gilts that received progesterone (200 mg/day) and prolactin or saline on Days 4-14 after ovariectomy on Day 4. On Day 15, there were no differences (P greater than 0.05) in any of the uterine secretory components measured. Hyperprolactinaemia (1 mg pig prolactin on Days 6-11) enhanced overall uterine secretory response on Day 12 to oestradiol (5 mg) administered on Day 11 compared to gilts that received 1 ml saline on Days 6-11 of the oestrous cycle. Total recoverable protein and leucine aminopeptidase activity were greater (P less than 0.05) for oestradiol-treated gilts, but effects of prolactin were not significant. Total recoverable glucose (P less than 0.01), PGF-2 alpha (P less than 0.02), uteroferrin (P less than 0.01) and specific activity of uteroferrin (P less than 0.001) were increased by prolactin and oestradiol, but not oestradiol alone. Calcium (P less than 0.05), chloride (P less than 0.05) and potassium (P less than 0.01) were increased in response to oestradiol. These results indicate an interaction between oestradiol and prolactin, but not progesterone and prolactin, which enhances secretion of some products of the pig uterine endometrium.

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PubMed1989

Intrauterine infusion of highly enriched bovine trophoblast protein-1 complex exerts an antiluteolytic effect to extend corpus luteum lifespan in cyclic cattle.

Intrauterine infusion of enriched bovine trophoblast protein-1 complex (bTP-1) resulted in extension of interoestrous intervals and corpus luteum function in cyclic cattle. Conceptus proteins were obtained by culture of Day 17-18 conceptuses for 72 h. Media from the first (n = 28), second (n = 26) and third (n = 19) 24 h of conceptus incubations were utilized. A highly enriched preparation of bTP-1 was obtained by a combination of ammonium sulphate precipitation, ion-exchange chromatography, and h.p.l.c. gel filtration. Degree of purity of the final preparation was confirmed by gel electrophoresis and immunoblotting with antiserum to ovine trophoblast protein-1. Jersey cattle (3 per group) received intrauterine infusions, twice daily from Day 15.5 to 21.0, of bovine serum albumin, the entire array of bovine conceptus secretory proteins (bCSP) from the 3 days of conceptus culture, or bTP-1. Infusions were via a catheter into the uterine horn ipsilateral to the corpus luteum. Oestrous cycle length in bTP-1-treated cows (26.1 +/- 1.3 days) was greater than for cows given BSA (19.5 +/- 1.3 days) or bCSP (21.5 +/- 1.3 days). Similarly, progesterone concentrations in serum remained elevated for a longer period of time for bTP-1-treated cows than for cows treated with BSA or bCSP. Residual variance associated with vena cava concentrations of PGF-2 alpha at Days 19-21 after oestrus (which included the variance between 15-min periods within cows) was reduced in cows treated with bTP-1 as compared to other groups. Lack of a bCSP effect may have been due to low amounts of bTP-1 in conceptus-conditioned medium from cultures of greater than 24 h. None the less, purified bTP-1 was effective in extending luteal function and appears to be the antiluteolytic agent of early pregnancy.

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PubMed1989

Effect of ovine trophoblast protein-1, oestrogen and progesterone on oxytocin-induced phosphatidylinositol turnover in endometrium of sheep.

In Exp. 1, endometrium was collected from Day-15 cyclic ewes and effects of oTP-1, oxytocin and oTP-1 + oxytocin, in various temporal relationships, on phosphatidylinositol (PI) turnover were determined. Co-treatment of endometrium with oTP-1 and oxytocin inhibited stimulatory effects of oxytocin, while treatment with oTP-1 before and during oxytocin administration had no effect. Turnover of PI was unaffected by oTP-1 alone. In Exp. 2, ovariectomized ewes were treated with progesterone (50 mg/day) for 10 days and then oestrogen (100 micrograms/day) for 2 days and endometrium was collected. Oxytocin stimulated PI turnover in endometrium, but oTP-1 had no effect alone or in combination with oxytocin. In Exp. 3, ovariectomized ewes were treated with corn oil (1 ml/day), oestrogen (50 micrograms/day), progesterone (50 mg/day) or progesterone + oestrogen for 10 days and endometrium was collected. Oxytocin stimulated PI turnover only in ewes that received progesterone. oTP-1 alone had no effect on PI turnover, while co-treatment of endometrium with oxytocin and oTP-1 stimulated PI turnover in ewes treated with progesterone, but not progesterone and oestrogen. Pretreatment of endometrium with oTP-1 stimulated PI turnover when ewes were treated with progesterone or progesterone + oestrogen. Pretreatment of endometrium with oxytocin and then treatment with oTP-1 inhibited PI turnover compared to treatment with oxytocin alone. In Exp. 4, ovariectomized ewes were treated as in Exp. 2. Catheters were placed into the uterine horns and ewes received oTP-1 into one horn and serum into the other twice daily on Days 10-12 of steroid treatment. Endometrium collected on Day 13 was used to measure PI turnover and received either no treatment or oxytocin. Oxytocin stimulated PI turnover in endometrium of these ewes and in-vivo treatment of the ewes with oTP-1 had no effect on PI turnover. These results indicate that antiluteolytic effects of oTP-1 are not mediated by inhibiting effects of oxytocin on phosphatidylinositol turnover if oxytocin receptors are present and that uterine responsiveness to oxytocin is progesterone dependent.

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PubMed1989

Differential growth factor content of uterine luminal fluids from large white and prolific Meishan pigs during the estrous cycle and early pregnancy.

Uterine luminal fluids (ULF) from Large White (LW) and prolific Chinese Meishan (MS) gilts were compared with respect to their peptide growth factor content during an estrous cycle and early pregnancy. Insulin-like growth factor-I (IGF-I) was quantitated by RIA; in vitro growth promoting properties of uterine luminal fluid mitogen (ULFM) were measured by [3H]thymidine incorporation into DNA of quiescent AKR-2B fibroblastic cells in culture. Peak concentrations (pg/microgram ULF protein) of IGF-I in ULF of Large White and Meishan gilts, respectively, were: estrous cycle, 9.8 +/- 1.4 (on d 10) and 39.7 +/- 7.8 (on d 12); gestation, 13.1 +/- 3.2 (on d 8 and 10) and 11.9 +/- 2.1 (on d 12), with differences among days (except d 10, P greater than .5) being affected by breed (P less than .10). For both breeds, there was a rapid decline in IGF-I concentrations by d 14 of the cycle and of pregnancy. Uterine luminal fluid mitogen activity was greater (P less than .01) for LW than for MS gilts on d 10 to 14 of an estrous cycle and gestation and diminished in a time-dependent manner in both breeds. No correlation was observed between IGF-I concentrations and uterine weights for either breed. In contrast, a negative correlation between uterine weight and ULFM activity was detected for cyclic (MS: r = -.855, P less than .10; LW: r = -.834, P less than .05) and pregnant (MS: r = -.806, P less than .10; LW: r = -.928, P less than .05) gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Comparative aspects of maternal recognition of pregnancy between sheep and pigs.

Sheep conceptuses secrete a protein, oTP-1, between Days 10 and 21 of gestation which is responsible for establishment of pregnancy. oTP-1 inhibits uterine production of luteolytic amounts of PGF-2 alpha (PGF) produced in response to oestradiol and oxytocin. oTP-1 does not compete with oxytocin for binding to oxytocin receptors, but may interfere with oxytocin stimulation of the inositol phospholipid system. Pig conceptuses secrete oestrogens between Days 10 and 15 of pregnancy which are essential for establishment of pregnancy. Oestrogens, directly or indirectly, alter secretion of PGF from an endocrine direction (towards uterine vasculature) to an exocrine direction (towards the uterine lumen). PGF sequestered in the uterine lumen is unavailable to exert a luteolytic effect on the CL. Pig conceptus secretory proteins stimulate uterine production of PGF and PGE. Conceptus secretory proteins of sheep and pigs include proteins which have antiviral activity and may be considered interferons. In sheep, oTP-1 has both antiluteolytic and antiviral properties. The specific pig conceptus secretory proteins(s) possessing antiviral activity has not been established. Unlike oTP-1, however, it does not appear to possess antiluteolytic activity.

Animals↗

PubMed1989

Antiluteolytic effects of bovine trophoblast protein-1.

Bovine conceptuses exert an antiluteolytic (anti-PGF-2 alpha) effect on the uterus by decreasing the secretion of PGF that results in maintenance of the CL. Basal and oxytocin-stimulated secretion rates of PGF from perifused endometrium are lower at Day 17 of pregnancy than at Day 17 of the oestrous cycle, probably because of increased amounts of an intracellular, endometrial PG-synthesis inhibitor which is present in the 100,000 g cytosolic supernatant, is proteinaceous, and acts in a noncompetitive manner with respect to arachidonic acid. The antiluteolytic signal in bovine conceptus secretory proteins (bCSP) is bovine trophoblast protein-1 (bTP-1), a group of 7 isomers of N-linked glycoproteins in two size classes (22,000 high-mannose and 24,000 complex types) that are related immunologically to ovine trophoblast protein-1 (oTP-1). Incubation of endometrial explants of Day-17 cyclic cows with bCSP and bTP-1 induced PG-synthesis inhibitor activity and reduced PGF secretion. Intrauterine infusion of bTP-1 from Days 15.5 to 21 extended the interoestrous interval from 19.5 to 26.0 days. Intrauterine infusion of interferon-alpha I 1 through the cervix from Day 15.5 to 21 extended the interoestrous interval from 22.8 to 26.8 days. Platelet-activating factor (PAF) and interferon-alpha I 1 alter PG secretion of endometrial explants (PAF decreases PGF and increases PGE-2; interferon-alpha I 1 does not alter PGF and increases PGE-2 secretion) but neither induces activity of the endometrial PG-synthesis inhibitor. In conclusion, bovine conceptuses exert a paracrine effect through the secretion of bTP-1 to induce an endometrial intracellular inhibitor of PGF synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

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