Characterization of decorin mRNA in pregnant intrauterine tissues of the ewe and regulation by steroids.
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In this study, we characterized the changes in the extracellular matrix proteoglycan decorin in pregnant intrauterine tissues in late gestation and in association with labor and delivery in sheep. In addition, we examined the effects of estradiol and progesterone on regulation of decorin mRNA expression in myometrium from the nonpregnant ovariectomized sheep. Using suppression subtractive hybridization in combination with Northern blot analysis, we identified a significant increase in decorin mRNA in the pregnant sheep myometrium during labor. The abundance of decorin mRNA paralleled myometrial contractility. The increase in decorin mRNA during labor was only demonstrated in the myometrium; no increase was observed in the endometrium or fetal membranes. Estradiol upregulated decorin mRNA and may act as a potential stimulator responsible for the increased decorin in the myometrium during parturition. The ovine decorin cDNA spans 1288 nt, includes 1083 nt of coding sequence predicted to encode a protein of 360 amino acids, 119 nt of 5'-untranslated region (UTR) and 86 nt of 3'-UTR. Over the coding region, the protein shares 79-96% nt sequence identity and 73-94% identity in the deduced amino acid sequence with homologous mammalian sequences. Using cloned decorin cDNA, we observed that the fibroblasts are the predominant cell type in the pregnant sheep myometrium containing decorin mRNA. These data suggest that increased decorin synthesis participates in the matrix changes that may play a role in myometrial activation. (+info)
Effect of vitamin A status at the end of term pregnancy on the saturation of retinol binding protein with retinol.
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BACKGROUND: Vitamin A (retinol), which is required for normal fetal development and successful gestation, circulates in the blood bound to a specific protein, the retinol binding protein (RBP). Little is known about the transport and metabolism of this complex protein or about retinol status during normal human pregnancy. OBJECTIVE: The aim of this study was to assess retinol status and transport modalities of retinol in well-nourished women with normal pregnancies, a population poorly investigated compared with pathologic and malnourished pregnant women. DESIGN: The maternal blood and cord blood concentrations of retinol, vitamin E, beta-carotene, RBP, and transthyretin of pregnant French women at term (n = 27) were measured and compared with values from a nonpregnant control group (n = 27). In addition, holo-RBP (retinol bound), apo-RBP (retinol free), and total protein were assessed in both groups to enable the hemodilution occurring during pregnancy to be taken into consideration and to evaluate the extent of saturation of RBP with retinol. RESULTS: Healthy pregnant women at term had normal serum circulatory amounts of retinol, vitamin E, binding proteins, and beta-carotene. However, they had less binding of retinol to RBP (holo-RBP: 49.9% in pregnant women, 54.0% in cord blood, and 77.5% in the control group). CONCLUSION: The results of this study suggest that retinol homeostasis and transport are modified during normal human pregnancy. (+info)
The regulation of prostaglandin output from term intact fetal membranes by anti-inflammatory cytokines.
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Prostaglandins are some of the main mediators which control parturition, and their production by intrauterine tissues can be up-regulated by pro-inflammatory cytokines. Anti-inflammatory cytokines may oppose these effects, and in this study we have investigated how two such cytokines affected fetal membrane function. Interleukin-10 (IL-10) inhibited the output of prostaglandin E2 (PGE2) from intact fetal membranes under basal and lipopolysaccharide (LPS)-stimulated conditions, and there was a parallel decrease in the expression of mRNA for COX-2. IL-10 also inhibited the production of interleukin-1beta (IL-1beta) and the expression of mRNA for IL-1beta, indicating that this cytokine has a broad anti-inflammatory effect. Transforming growth factor-beta1 (TGF-beta1), which is generally considered to be anti-inflammatory had opposite effects on PGE2 production, in that it increased the output of PGE2 for up to 8 hr. TGF-beta1 increased levels of type-2 cyclo-oxygenase (COX-2) and cytosolic phospholipase A2 (cPLA2) protein, and also activated the cPLA2 enzyme present; the profile of effects is similar to that of the pro-inflammatory cytokine IL-1beta, and was not expected. Combinations of TGF-beta1 with IL-1beta also increased PGE2 output and caused appropriate changes in prostaglandin pathway enzymes, whereas TGF-beta1 and IL-1alpha had more limited effects. Further studies are needed to establish the physiological significance of these findings, but TGF-beta1 does not seem to act as an inhibitory cytokine in intact fetal membranes at term. (+info)
Pregnancy and exogenous steroid treatments modulate the expression of relaxant EP(2) and contractile FP receptors in the rat uterus.
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Prostaglandins (PGs) interact with specific receptors on plasma membranes to regulate myometrial activity in many species. The present study examined whether the expression of relaxant prostaglandin E receptor subtype two (EP(2)) and contractile prostaglandin F receptor (FP) mRNA in the rat uterus is changed during various states of pregnancy and regulated by steroid hormones. Expression of mRNA for EP(2) and FP receptors in the full-thickness uteri was analyzed by reverse transcription-polymerase chain reaction using specific primers. Abundance of receptor mRNA was expressed relative to beta-actin mRNA. Results showed that 1) mRNA for EP(2) receptors in the rat uterus was substantially increased during pregnancy (320%) compared with the nonpregnant state (100%, P < 0.01), and declined during labor at term (36% vs. 100% in control, P < 0.01); 2) mRNA expression for FP receptors in rat uterus was increased during pregnancy (333% vs. 100% in nonpregnant rats, P < 0. 01) and reached maximal levels during labor (515% vs. 100% in control, P < 0.01); 3) upon RU-486 treatment on Day 19 of pregnancy, uterine EP(2) receptor mRNA levels were decreased (18% vs. 100% in control, P < 0.01), and FP mRNA levels were increased (357% vs. 100% in control, P < 0.01); 4) with ICI 164384 (an antiestrogen) treatment on Day 19 of gestation, uterine FP receptor mRNA levels were decreased without effects on EP(2) receptors; 5) in ovariectomized (ovx) rats, progesterone increased EP(2) (163% vs. 100% in control, P < 0.01) and had no effects on FP receptor mRNA expression in the rat uterus; 6) estradiol increased FP receptor mRNA levels (358% vs. 100% in control, P < 0.01) and had no effects on EP(2) mRNA in the ovx rat uterus. Therefore, we conclude that steroid hormones modulate the mRNA for relaxant EP(2) and contractile FP receptors for PGs in the uterus and thus regulate uterine activity during pregnancy and labor. (+info)
Fetal-to-maternal progression of prostaglandin H(2) synthase-2 expression in ovine intrauterine tissues during the course of labor.
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We examined whether spontaneous parturition in sheep was associated with tissue-specific changes in prostaglandin H(2) synthase-2 (PGHS-2) expression and/or with altered expression of myometrial EP and FP receptors. Placental and uterine tissues were collected from three groups of chronically catheterized sheep in relation to term spontaneous labor: late pregnancy, not in labor; early labor; and active labor. Expression of PGHS-2 mRNA and protein was determined by in situ hybridization, Western blotting, and immunohistochemistry. Semiquantitative reverse transcription-polymerase chain reaction was used to assess the presence of and changes in prostaglandin (PG) receptor subtypes. In placenta, PGHS-2 mRNA and protein localized to trophoblast uninucleate cells and tended to increase with early labor. PGHS-2 mRNA and protein localized to endometrial epithelium and to myometrium, where PGHS-2 protein levels rose in active labor tissues. Concentrations of PGE(2) in fetal plasma rose progressively with labor, whereas 13,14-dihydro-15-keto-PGF(2alpha) in maternal plasma increased significantly only in active labor. Messenger RNA encoding four EP receptor subtypes and FP receptor were present in myometrium, but levels did not change with labor. We suggest that spontaneous labor in sheep is associated with a progressive increase in PGHS-2 expression in a temporal and tissue-specific manner from trophoblast to maternal tissues, rather than alteration in PG receptor gene expression. (+info)
Production of inhibin forms by the fetal membranes, decidua, placenta and fetus at parturition.
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Inhibins are regulators of paracrine and endocrine function during pregnancy, but their intrauterine sites of secretion are not well established. In amniotic fluid, inhibin A-, inhibin B- and inhibin pro-alphaC-containing isoforms were present in high concentrations, whereas in maternal serum, inhibin A and pro-alphaC forms were present in high amounts, with low concentrations of inhibin B. In fetal cord serum, inhibin pro-alphaC was present in all samples, inhibin B was detectable in male but not female fetuses, with no detectable inhibin A in either sex. From cultured explants, both inhibin A and B were secreted by chorion laeve, whereas only inhibin A was secreted by placenta, with both tissues secreting inhibin pro-alphaC. Only low concentrations of both dimeric inhibins and pro-alphaC forms were secreted by decidua parietalis and amnion. The dual perfused placental cotyledon secreted both inhibin A and pro-alphaC into maternal perfusate, but only inhibin pro-alphaC into the fetal circulation and less than to the maternal side. We conclude that trophoblast is the predominant source of dimeric inhibins, but with markedly different secretion depending on its intrauterine location. There was a significant decrease in inhibin A and pro-alphaC in amniotic fluid collected at term active labour compared to elective Caesarean section (P < 0.001). This may reflect a local change in inhibin/activin processing at labour, likely in chorion laeve trophoblast cells, which may be important in the paracrine control of the feto-maternal communication required to maintain pregnancy and initiate labour. (+info)
Combined spinal-epidural analgesia in labour: comparison of two doses of intrathecal bupivacaine with fentanyl.
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We have compared intrathecal bupivacaine 1.25 mg and fentanyl 25 micrograms (group A) with bupivacaine 2.5 mg and fentanyl 25 micrograms (group B), for combined spinal-epidural analgesia in 49 labouring parturients in a prospective, randomized, double-blind study. Onset and quality of analgesia were similar in both groups, with median visual analogue scale pain scores of 0 achieved in 5-10 min. Median duration of analgesia was longer in group B (median 120 (range 90-120) min) compared with group A (75 (75-105) min) (P = 0.013). Median upper sensory level was higher in group B compared with group A at 15 min (T6-7 vs T11, P = 0.003) and at 30 min (T6 vs T11-12; P = 0.001). Motor block was greater in group B: seven patients had a modified Bromage score > or = 1 compared with none in group A at 15 min (P = 0.017). Group B also had a greater decrease in arterial pressure. Patient-midwife satisfaction scores and other side effects were similar. We conclude that intrathecal bupivacaine 1.25 mg with fentanyl 25 micrograms provided analgesia of similar onset and quality compared with bupivacaine 2.5 mg and fentanyl 25 micrograms. Although the duration of analgesia was shorter, the incidences of motor block and hypotension were less with the smaller dose. (+info)
Effects of dietary fatty acids on reproduction in ruminants.
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Fats in the diet can influence reproduction positively by altering both ovarian follicle and corpus luteum function via improved energy status and by increasing precursors for the synthesis of reproductive hormones such as steroids and prostaglandins. Dietary fatty acids of the n-3 family reduce ovarian and endometrial synthesis of prostaglandin F2alpha, decrease ovulation rate in rats and delay parturition in sheep and humans. Polyunsaturated fatty acids such as linoleic, linolenic, eicosapentaenoic and docosahexaenoic acids may inhibit prostaglandin F2alpha synthesis through mechanisms such as decreased availability of its precursor arachidonic acid, an increased competition by these fatty acids with arachidonic acid for binding to prostaglandin H synthase, and inhibition of prostaglandin H synthase synthesis and activity. It is not known whether polyunsaturated fatty acids regulate expression of candidate genes such as phospholipase A2 and prostaglandin H synthase via activation of nuclear transcription factors such as peroxisome proliferator-activated receptors. Manipulation of the fatty acid profile of the diet can be used potentially to amplify suppression of uterine synthesis of prostaglandin F2alpha during early pregnancy in cattle, which may contribute to a reduction in embryonic mortality. Feeding fats and targeting of fatty acids to reproductive tissues may be a potential strategy to integrate nutrition and reproductive management to improve animal productivity. (+info)