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PubMedDate not supplied

Differential effects of betamethasone and dexamethasone fetal administration of parturition in sheep.

OBJECTIVE: We tested the hypothesis that betamethasone is more potent than dexamethasone in inducing the essential mechanisms of parturition in sheep. METHODS: Twenty-one sheep were instrumented under general anesthesia with maternal and fetal arterial and venous catheters and myometrial electromyogram electrodes at 117 days' gestation (dGA). At 125 dGA at 12:00 PM, after 2 days of baseline recording, either saline (n = 7, control group), betamethasone (n = 7), or dexamethasone (n = 7) was administered into the fetal jugular vein at a rate of 10 micrograms/hour. A total dose of 0.48 mg was given over the next 48 hours. The animals underwent autopsy 3 days after the end of the infusion period (130 dGA), or earlier if labor resulted from the glucocorticoid administration. Daily maternal and fetal arterial blood samples (4 mL) for hormone measurement were taken at 10:00 AM throughout the study period. Additional arterial blood samples were taken if the animal developed labor. Maternal plasma progesterone and fetal ACTH and cortisol concentrations were measured by radioimmunoassay, and corticosteroid-binding globulin (CBG) binding capacity was determined by saturation analysis. Myometrial activity was monitored continuously throughout the experimental protocol. RESULTS: All seven betamethasone-treated animals developed labor after the glucocorticoid infusion regimen. In contrast, only two of seven dexamethasone-treated animals developed labor. Fetal treatment with betamethasone produced a greater and earlier fall in maternal plasma progesterone than fetal treatment with dexamethasone. Both betamethasone and dexamethasone treatments elevated fetal plasma CBG to similar binding capacities. Elevated fetal plasma ACTH and cortisol concentrations at the end of the infusion period in both betamethasone-and dexamethasone-treated animals were not related to the development of labor-type contractions. CONCLUSION: These data support the hypothesis that betamethasone is more potent than dexamethasone in inducing the essential mechanisms of parturition in sheep.

Adrenocorticotropic Hormone↗
PubMed1996

An investigation on plasma progesterone levels during pregnancy and at parturition in the Ivesi sheep.

In this study, plasma progesterone concentrations in a total of 45 Ivesi sheep were investigated during pregnancy and at parturition. Blood samples were collected from all the sheep studied every 20 days commencing on the 30th day of pregnancy. Plasma progesterone levels were determined by radioimmunoassay. During the second half of the pregnancy, progesterone concentrations in the sheep giving birth to one, two and three lambs were 2.02 +/- 0.08 ng/ml, 3.24 +/- 1.18 ng/ml and 4.90 +/- 0.85 ng/ml, respectively. There was no significant variation in progesterone levels between sheep with male and female offspring. At parturition, plasma progesterone concentrations did not differ significantly between the animals. The present results indicate that plasma progesterone levels could be used not only to determine the pregnancy status of the animal but also to predict the number of fetuses after the second half of the pregnancy.

Animals↗
PubMed1997

Treatment of dairy cows at parturition with prostaglandin F2 alpha or oxytocin for prevention of retained fetal membranes.

OBJECTIVE: To evaluate the effects of treatment at parturition with dinoprost tromethamine, fenprostalene, or oxytocin on postpartum disease and reproductive performance during the subsequent breeding season in dairy cows. DESIGN: Prospective study. ANIMALS: 1,400 Holstein cows from 5 commercial dairies. PROCEDURE: Cows were assigned within 2 hours after calving to serve as untreated control cows or to be treated with 1 mg of fenprostalene, SC; 25 mg of dinoprost tromethamine, IM; or 20 IU of oxytocin, IM. Cows were confined to treatment pens and monitored daily until fetal membranes were expelled. Cows with retained fetal membranes (RFM) were treated according to existing treatment protocols for the dairy, with the provision that intrauterine infusions were not allowed. All other disease conditions were recorded, and appropriate treatment was administered. Postpartum reproductive examinations were performed 28 to 56 days after parturition Breeding records were maintained for all cows until pregnancy was confirmed or the cow was removed from the herd. RESULTS: Fetal membranes were retained in 12.1% of all cows, and this outcome was unaffected by treatment. Compared with cows without RFM, cows with RFM had longer intervals to first insemination (76.4 vs 82.0 days), reduced first insemination conception rates (46.8 vs 28.0%), and increased number of days not pregnant (103.2 vs 127.4 days). Farm, as a variable, significantly affected development of RFM and postpartum disease conditions as well as reproductive performance during the subsequent breeding season. Fetal membranes were retained in 12.4, 15.2, 8.7, 6.3, and 16.9% of cows on farms 1, 2, 3, 4, and 5, respectively. Mean days to first insemination varied from 64.5 days (farm 3) to 91.5 days (farm 1). Mean number of days not pregnant varied from 94.8 days (farm 3) to 15.9 days (farm 4). CLINICAL IMPLICATIONS: Administration of prostaglandins or oxytocin at the time of calving does not reduce the incidence of RFM or improve reproductive performance. Farm management practices have the greatest impact on dairy cow performance.

Abortifacient Agents, Nonsteroidal↗
PubMed1998

A method for regulating the duration of pregnancy and the time of parturition in Sprague-Dawley rats (Charles River CD strain).

A method of shifting the dark phase of the 12/12 hr photoperiod cycle on Day 7 of pregnancy is described for regulating the duration of pregnancy to 22 days and assuring that most parturitions take place between 1100 and 1500 hr. This method, in addition, has the added convenience that matings can occur during normal laboratory hours between 0700 and 1900 hr during the dark phase of the photoperiodic cycle. Litter sizes are normal (mostly 14-16 pups) and postpartum estrus behavior occurs at the normal interval of 4 to 11 1/2 hr after parturition.

Animals↗
PubMedDate not supplied

[Incidence of MMA after prostaglandin-induced parturition (author's transl)].

In a sowherd suffering from high incidence of MMA which demanded an intensive postparturient treatment to reduce baby pig mortality the effect on postparturient diseases of induction of parturition with Prostaglandin was examined. After treatment of 19 sows on day 112 of gestation with 12.5 mg Prostaglandin, parturition in 15 sows took place on an average of 25 hours after injection; the gestation period was 113.1 +/- 0.5 days. Three sows that did not respond to the treatment farrowed 3-6 days after treatment and one sow farrowed few hours after treatment. In a non-treated identical group of animals the gestation period averaged 113.4 +/- 1.5 days. No difference was found between the two groups concerning number of stillborn pgis, baby pig mortality within first eight days of life, incidence of MMA or intensity of postparturient medical treatment.

Animals↗
PubMed1976

Sequential changes of estrogens and progesterone at prostaglandin-induced parturition in the sow.

Parenteral administration of prostaglandin F2alpha (PGF2alpha) is efficient in inducing parturition in late pregnant swine. The purpose in the present study was to investigate the sequential changes of progesterone and estrogens at prostaglandin-induced parturition in the sow. Six of 7 sows (86%) treated once intramuscularly with 12.5 mg of PGF2alpha on days 110, 111, 112, or 113 of pregnancy farrowed within 39 hours after the injection. One PGF2alpha-treated sow and 2 sows given placebo injections on days 110 and 111 of pregnancy farrowed 90 to 130 hours later. The injection of PGF2alpha decreased the peripheral plasma concentration of progesterone in a manner similar to that observed immediately prepartum in normally farrowing sows. Estrogen patterns were similar in PGF2alpha-treated and control sows.

Animals↗
PubMed1998

Regulation of parturition update. Endocrine and paracrine effectors of term and preterm labor.

This article summarizes the role of endocrine and paracrine mediators of human parturition. Gonadal steroids (17 beta--estradiol and progesterone) mediate many of the decidual and uterine contractile functions during early events in labor. Proinflammatory cytokines and chemokines orchestrate many of the events triggering or sustaining active labor at term and in the preterm setting. Several autacoids (prostaglandins, platelet-activating factor) serve proximal activities such as uterine contractility and remodeling of the cervical extracellular matrix leading to dilatation and effacement. As the biochemical participants during parturition become more clearly understood, it will be possible to develop improved surveillance, management, and treatment strategies for preterm labor.

Autacoids↗
PubMed2004

Reciprocal expression of peroxisome proliferator-activated receptor-gamma and cyclooxygenase-2 in human term parturition.

OBJECTIVE: The objective of this study was to test the hypothesis that peroxisome proliferator activated receptor-gamma (PPAR-gamma) is expressed in intrauterine tissues before active term human parturition, and that its repression is associated with up-regulation of cyclooxygenase-2 (COX-2). STUDY DESIGN: Specimens were collected from women with term singleton pregnancies after spontaneous labor or cesarean section before labor, prepared for immunoblot and immunohistochemical analysis, and probed for PPAR-gamma or COX-2. RESULTS: PPAR-gamma expression was prominent in fetal membranes and placenta before active labor. After labor, PPAR-gamma expression was significantly reduced in fetal membranes, but not in placenta. The ratio of COX-2:PPAR-gamma was significantly elevated in fetal membranes with labor. PPAR-gamma immunostaining was prominent in syncytiotrophoblast, extravillous cytotrophoblasts, and cells of the amnion and chorion. COX-2 immunostaining was abundant in the amnion and rare in the placenta. CONCLUSION: PPAR-gamma is highly expressed in term intrauterine tissues. In fetal membranes, PPAR-gamma levels are reduced once active labor commences, coincidental with a relative increase in COX-2 expression.

Adult↗
PubMed2006

A questionnaire-based study of gestation, parturition and neonatal mortality in pedigree breeding cats in the UK.

This study was based on a convenience-sampling questionnaire study of pedigree cat breeding in the UK. Data were collated for the births of 1,056 litters from 14 different pedigree breeds and 942 different households. Significant relationships between various outcomes and relevant predictors were assessed by multiple linear regression or logistic regression as appropriate. The overall mean gestation length of 65.1 days varied significantly between the breeds (P<0.0001), and larger litter sizes were associated with shorter gestation lengths (P=0.04). The mean litter size of 4.6 kittens also varied significantly according to breed (P<0.0001). The weight of kittens born alive (overall mean 93.5 g) increased with longer gestation lengths (P=0.0003), decreased with larger litter sizes (P<0.0001) and varied between the breeds (P<0.0001). A total of 8.0% of pregnancies resulted in a caesarean section, with a higher risk associated with smaller litter sizes (P=0.002). Although the frequency of caesarean sections varied from 0 to 18.5% between individual breeds, breed itself was not shown to have a significant independent effect on this likelihood. A mean of 7.2% of all the kittens were stillborn, which varied according to breed (P=0.0003), and the risk of a stillborn kitten increased with litter size (P=0.0001), and with the presence of congenital defects in the litter (P=0.0002). The mean kitten mortality between birth and 8 weeks of age was 9.1%, and the majority of these occurred in the first week of life. Parturition intervals varied widely. The duration of first stage of labour was less than 2h in 82.9% of cats. The interval between the birth of the first and last kitten was less than 6h in 85.7%, but more than 48 h in three cats. A maximum of 48 h was recorded between the births of individual kittens in unassisted deliveries.

Animals↗
PubMed2006

Expression of cyclooxygenase-II (COX-II) and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD)/prostaglandin F-synthase (PGFS) in bovine placentomes: implications for the initiation of parturition in cattle.

The chain of events leading to prepartal luteolysis in cattle is not yet fully understood. Prostaglandin F(2alpha) (PGF(2alpha)) seems to be a major factor involved. However, only little information is available about the underlying regulatory mechanisms. Consequently, the expression of cyclooxygenase-II (COX-II) and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD), an enzyme recently shown to be most likely responsible for the production of luteolytic PGF(2alpha) in the endometrium of cyclic cows, was investigated in bovine placentomes. Immunohistochemical methods were applied to placentomes from 17 pregnant cows between days 100 and 284, from three cows during the prepartal progesterone decrease (days 273-282) and from five parturient cows. COX-II was found in uninucleated trophoblast cells (UTC) from day 100 until parturition. However, between days 100 and 235 expression was only weak to moderate, focal and mainly restricted to the chorionic plate and adjacent basal parts of chorionic stem villi. In placentomes from a 270 and a 284 day pregnant cow, in which the prepartal decline of progesterone levels had not started yet, staining had substantially increased and extended to secondary and tertiary chorionic villi. In prepartal and parturient cows strong to intense staining was present in UTC all over the villous tree. Real time RT-PCR confirmed an extensive pre- and intrapartal rise of COX-II expression in bovine placentomes with a 70-100-fold increase of COX-II-mRNA levels. 20alpha-HSD/PGFS was widely expressed in UTC of chorionic villi. Like COX-II it was down-regulated in UTC differentiating into trophoblast giant cells. Immunostaining pattern did not change remarkably during the period under investigation, and 20alpha-HSD/PGFS-mRNA levels increased only 2.6-fold in the prepartal phase. Thus, in UTC PGF(2alpha) may be produced via COX-II and 20alpha-HSD/PGFS, but only COX-II may be substantially involved in the control of a putative prepartal placentomal output of luteolytic PGs, whereas 20alpha-HSD/PGFS seems to be expressed in a more constitutive manner.

20-alpha-Hydroxysteroid Dehydrogenase↗
PubMed2004

Phospholipase A2 isozymes in pregnancy and parturition.

Mammalian cells contain several structurally different phospholipase (PLA2) enzymes that exhibit distinct localisation, function and mechanisms of regulation. PLA2 isozymes have been postulated to play significant roles in the parturition process. Both secretory and cytosolic PLA2 isozymes have been identified in human gestational tissues, and there is differential expression of these PLA2 isozymes in human fetal membranes and placenta obtained at preterm and term. The aims of this commentary are: (1) to review recent data concerning the expression, role and regulation of PLA2 isozymes in human gestational tissues; and (2) to present novel data demonstrating the regulation of PLA2 isozymes in human gestational tissues by nuclear factor-kappa B (NF-kappaB) and peroxisome proliferator-activated receptor (PPAR)-g.

Female↗
PubMed2004

Topographical specialization of prostaglandin function in late pregnancy and at parturition in the baboon.

Prostaglandins play key central roles in both the maintenance of pregnancy and parturition. Extensive data exist from studies in human pregnancy but the needs of clinical management and the inability to conduct carefully controlled perturbation studies in human pregnancy make it necessary to obtain information from nonhuman primate models. We have used the pregnant baboon to evaluate production, metabolism and receptor mediated actions of prostaglandins in late gestation to demonstrate that expression of key genes is tightly controlled in enzyme-specific, gestation age-specific, tissue-specific and uterine region-specific fashion.

Animals↗
PubMed2004

Parturition in gilts: duration of farrowing, birth intervals and placenta expulsion in relation to maternal, piglet and placental traits.

Large White x Meishan F2 crossbred gilts (n = 57) were observed continuously during farrowing while the placentae of their offspring were labeled in order to examine the duration of farrowing and placenta expulsion in relation to maternal-, piglet- and placental traits and the duration of birth interval in relation to birth weight, birth order and placental traits. Independently from each other, litter size, gestation length and offspring directed aggression significantly (P 0.05) affected duration of farrowing. An increase in litter size was associated with an increase of duration of farrowing and an increase in gestation length was associated with a decrease of duration of farrowing. Aggressive gilts took longer to farrow, compared to non-aggressive ones. After taking into account litter size, gestation length and offspring directed aggression, placental thickness (i.e., placental weight corrected for placental surface area) was significantly (P < 0.05) related to duration of farrowing, i.e., litters with on average thicker placentae took longer to farrow. The latter effect is the result of the fact that individual placental thickness significantly (P < 0.01) affected individual birth interval, independent of birth weight. The piglet has to break its own membranes to be able to start its journey through the uterus towards the birth channel. Apparently, a thicker placenta offers more resistance and thus prolongs the process of birth. Independent of placental thickness, birth interval significantly (P < 0.01) decreased with an increase in birth order (first born to last born). The high variation of birth intervals for the last born piglets, caused a slight increase in average birth interval for the latter piglets. Litters with on average more areolae per placenta took significantly (P < 0.001) less time to be born than litters with on average less areolae per placenta (independent of total number of piglets born and other placental traits), while birth intervals within litters were not affected by this trait. Thus, these results are probably due to a gilt trait rather than a piglet trait. Since the number of areolae represent the number of uterine glands present, the gilt trait might be uterine development. Duration of placenta expulsion significantly (P < 0.01) increased with an increase of duration of farrowing. Furthermore, the first placenta was expelled significantly (P < 0.01) earlier relative to last piglet when duration of farrowing was protracted, while there was no relation of the time interval between first placenta and last piglet and the duration of placenta expulsion. In conclusion, the most important finding of this study is that placental thickness rather than birth weight appears to play an important role in the duration of birth intervals and as a result, of duration of parturition in gilts.

Aggression↗
PubMed2002

Dopamine antagonists during parturition disrupt maternal care and the retention of maternal behavior in rats.

Brief contact with pups at parturition enables the female rat to establish and retain the full repertoire of maternal behaviors, allowing her to respond rapidly to pups in the future. To determine whether the dopamine system is involved in the retention of maternal behavior, females were continuously infused with dopamine antagonists during the periparturitional period and then allowed either a brief interaction period with pups (3 h) or no interaction with pups (pups removed as they were born). Females were exposed to either the D1-like antagonist SCH 23390 (0.1 or 1.0 mg/kg/day) or the D2-like antagonist clebopride (0.5 or 1.0 mg/kg/day). The high dose of either DA antagonist resulted in significant attenuation of maternal care immediately postpartum. When tested for the retention of maternal behavior 7 days later, however, only the females exposed to the D2 antagonist displayed a delayed response to shown full maternal behavior (FMB) towards donor pups. Thus, while both dopamine receptor subtypes appear necessary for the full and rapid expression of maternal behavior during the early postpartum period, only the D2 receptor subtype appears to be involved in the retention of this behavior.

Animals↗
PubMed2003

The role of prostaglandins in the initiation of parturition.

Parturition is composed of five separate but integrated physiological events: fetal membrane rupture, cervical dilatation, myometrial contractility, placental separation and uterine involution. Prostaglandins (PGs) have central roles in each of these, but the most studied is myometrial contraction. Elevated uterine PGs or the enhanced sensitivity of the myometrium to PGs leads to contractions and labour. The regulator of PG synthesis is the mRNA expression of PGHS-2. Cytokines are important stimulators of this gene expression, and cortisol and other factors may be as well. This enzyme is an important therapeutic target in the prevention of preterm labour. Some preterm births occur without an elevation of uterine PGs, even though they are delayed by non-steroidal anti-inflammatory drugs (NSAIDs), suggesting enhanced myometrial sensitivity to PGs. The PGF(2alpha) receptor, FP, is emerging as a central component of uterine sensitivity and may prove to be involved with preterm birth and a reasonable target for tocolysis.

Cyclooxygenase 2↗
PubMed2003

Impact of parturition on iron status in nonanaemic iron deficiency.

BACKGROUND: Iron-deficient nonanaemic parturients risk underdiagnosis as a result of the reliance on postpartum ferritin and haemoglobin as markers of iron status. Ferritin is an acute-phase protein whose levels increase during the inflammatory response, as occurs after delivery. Our aims were to evaluate the impact of parturition on iron status, erythropoiesis and the inflammatory response, and identify the optimal parameters and timing for diagnosing iron deficiency in the presence of postpartum inflammation. MATERIALS AND METHODS: Conventional parameters of iron status, erythropoiesis and the inflammatory response (serum ferritin, serum iron, transferrin saturation, C-reactive protein) were compared with more recent parameters [soluble transferrin receptors (sTfR), hypochromic red cells, reticulocyte indices] within 48 h either side of delivery in 64 iron-deficient nonanaemic women (defined by a prepartum serum ferritin < or =15 microg L(-1), and a pre- and postpartum haemoglobin of > or =11.0 g dL(-1) and > or =10.0 g dL(-1), respectively). RESULTS: Mean sTfR decreased pre to postpartum from 7.3 to 5.8 microg mL(-1) (P<0.01), while mean serum ferritin increased from 9.7 to 16.9 microg L(-1) (P<0.01). Serum ferritin did not correlate with haemoglobin pre or postpartum (r=0.04, P=0.7; r=0.2, P=0.09), but a correlation persisted postpartum between hypochromic red blood cells and haemoglobin (r=-0.26; P<0.05). The percentage of hypochromic red cells remained virtually unchanged pre- and postpartum (4.0% vs. 3.8%; NS). Postpartum mean reticulocyte haemoglobin content (CHr) was 27.1 +/- 1.6 pg. CONCLUSION: Iron status should be tested prepartum, in the absence of an inflammatory response, rather than in the early postpartum. A valuable additional parameter, where available, might be the hypochromic red cell percentage, which is virtually uninfluenced by the inflammatory response. Furthermore, hypochromic red cell percentage, CHr and sTfR can be helpful to differentiate between functional iron deficiency and depleted iron stores.

Adult↗
PubMed2002

Uptake of alpha-tocopherol by the mammary gland but not by white adipose tissue is dependent on lipoprotein lipase activity around parturition and during lactation in the rat.

This study was undertaken to test the potential role of changes in lipoprotein lipase (LPL) activity in the mammary gland and adipose tissue around parturition and lactation on the uptake of alpha-tocopherol in the rat. Plasma levels of alpha-tocopherol and triglycerides were higher in 20-day pregnant rats than in virgin rats, whereas its concentration was higher in the mammary gland of the former, and no differences were detected in adipose tissue between the groups. After an oral alpha-tocopherol and triglyceride load, both appeared in plasma faster in pregnant rats than in virgin rats, the change being even faster for alpha-tocopherol than for triglycerides. After 24 hours, both alpha-tocopherol and triglycerides in d < 1.006 lipoproteins were higher in pregnant rats than in virgin rats, LPL activity was higher in the mammary gland, and lower in adipose tissue in the former, whereas alpha-tocopherol concentration also appeared higher in the mammary gland of pregnant rats, and no differences were detected between the groups in adipose tissue. At day 13 of lactation, an oral load of alpha-tocopherol and triglycerides caused a higher increase of plasma alpha-tocopherol levels than triglycerides, and this effect decreased when rats had their litter removed 48 hours before analysis. In these litter-removed rats, the appearance of alpha-tocopherol and triglycerides in plasma was higher in d < 1.006 lipoproteins than in lactating rats. Also, both LPL activity and alpha-tocopherol concentration in the mammary gland plus milk was lower in litter-removed rats than in the lactating rats, whereas LPL in adipose tissue was higher in the former, although no difference in alpha-tocopherol was found. Thus, data are consistent with the role of LPL activity in the mammary gland modulating the uptake of alpha-tocopherol during pregnancy and lactation, although this is not true in adipose tissue.

Adipose Tissue↗