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PubMed1977

Release of neurophysins I and II during and after parturition in cows.

Bovine neurophysin I and neurophysin II (bNpI and bNpII) have been assayed by radioimmunoassay in the jugular venous blood of cows during parturition. In general, low bNpI levels were detected on the day before labour began and during the first stage of labour. Neurophysin I was present in appreciable quantities in blood taken during the second stage of labour and in most cows the concentrations rose to a maximum during the expulsive stage. After delivery, the concentration of bNpI in the blood diminished. This pattern of release is similar to that reported for oxytocin at parturition in cows. As with bNpI, maximum levels of bNpII occurred during the expulsive stage of labour in some animals. In others, bNpII concentrations were very low or absent. Low concentrations of bNpII were found at the other stages of labour. Examination of the results from individual animals indicated that the release of the two neurophysins can be independent.

Animals↗
PubMed1985

Release of oxytocin during suckling and parturition in the rat.

A highly sensitive and specific radioimmunoassay (RIA) for oxytocin was developed and used to measure oxytocin concentrations during both suckling and parturition in individual rats. In urethane-anaesthetized rats, the suckling stimuli, provided by ten pups, induced intermittent increases in intramammary pressure of about 10 mmHg. This was associated with a significant (P less than 0.01) increase in serum oxytocin levels from 19.5 +/- 4.5 (S.E.M., n = 9) to 49.1 +/- 7.4 pmol/l (n = 9) in the samples taken within 30 s from the time of the peak in the pressure. These rises in serum oxytocin returned rapidly to the basal levels as expected from the short half-life (1.46 min) of oxytocin in general circulation. On day 22 or 23 of gestation, serum oxytocin levels remained stable until 0-0.5 h before the first fetus was expelled. They then increased significantly (P less than 0.01) from 27.6 +/- 4.6 pmol/l (n = 19) in samples taken 0-0.5 h before to 45.1 +/- 5.6 pmol/l in samples taken after the expulsion of the first fetus and gradually increased until the last fetus was expelled. Serum oxytocin concentrations then declined but remained higher than those observed before the first fetus had been born until at least 1-1.5 h after the expulsion of the last fetus. Thus, this oxytocin RIA revealed increased concentrations of the hormone in blood during both suckling and parturition in the rat.

Animals↗
PubMed1989

Ovine placental steroid 17 alpha-hydroxylase/C-17,20-lyase, aromatase and sulphatase in dexamethasone-induced and natural parturition.

Parturition in the sheep is preceded by an abrupt alteration in placental steroid metabolism causing a shift from progesterone to oestrogen production. This change is believed to be a consequence of the preparatum rise in cortisol in the fetal circulation and involves increases in activities of the enzymes steroid 17 alpha-hydroxylase (cytochrome P-450(17) alpha), steroid C-17,20-lyase, and possibly aromatase and steroid sulphatase. The activity levels have been determined of steroid 17 alpha-hydroxylase, aromatase and steroid sulphatase in placental microsomes in late pregnancy, dexamethasone-induced labour and in natural labour at term. Over the gestational period of 118-140 days, basal levels of placental aromatase were relatively constant (mean value (+/- S.E.M.) of 5.6 +/- 0.5 pmol/min per mg microsomal protein (n = 10]. Pregnenolone and progesterone 17 alpha-hydroxylase activities were undetectable (less than 0.5 pmol/min per mg microsomal protein (n = 7]. In six animals in labour induced with infusion of dexamethasone into the fetus, placental aromatase activity increased to a value of 14.0 +/- 1.0 pmol/min per mg protein; placental pregnenolone 17 alpha-hydroxylase, measured in four of the animals, also increased to 453 +/- 77 pmol/min per mg microsomal protein. In five animals in natural spontaneous labour with vaginal delivery, aromatase activity was 26.7 +/- 5.2 pmol/min per mg microsomal protein and pregnenolone 17 alpha-hydroxylase activity was 141 +/- 14 pmol/min per mg microsomal protein. Steroid sulphatase activity was barely detectable (less than 1.5 pmol/min per mg microsomal protein) during late pregnancy, dexamethasone-induced labour or natural parturition.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldehyde-Lyases↗
PubMed1998

Effects of relaxin, pregnancy and parturition on collagen metabolism in the rat pubic symphysis.

The aim of this study was to examine the changes in collagen metabolism that occur during pregnancy and parturition and upon relaxin administration to the rat pubic symphysial interpubic tissue. Pubic symphyses were collected from non-pregnant, and intact and ovariectomised pregnant Sprague-Dawley rats at days 15, 18 and 21 of pregnancy as well as during and after delivery, and analysed for collagen content and solubility. SDS-PAGE was used to determine collagen composition. During pregnancy and particularly during birth, there was a significant reduction in both the tissue wet (57+/-3%) and dry (43+/-3%) weight (n=7), which coincided with a significant increase in water content (to 80%) and was attributed to a significant (P<0.05) reduction in overall tissue collagen content (by 47+/-2%). This resulted in both soluble (10%) and insoluble (90%) collagen levels being reduced, but gel electrophoresis demonstrated the presence of types I, II and V collagen in all samples. Western blot analysis confirmed the presence of type II collagen throughout pregnancy, confirming that the rat pubic symphysis remained a fibrocartilaginous tissue throughout gestation. In the absence of the ovaries and hence relaxin, tissue collagen content and solubility were not significantly different from control measurements. However, tissues of ovariectomised animals treated with oestrogen and progesterone (pellets) and relaxin (injection) contained collagen levels that mimicked those of late pregnancy and parturition. These results suggest that relaxin plays an important role in regulating collagen catabolism during gestation in the rat.

Analysis of Variance↗
PubMed1999

Pregnancy, parturition, and lactation in hypophyseal stalk-transected beef heifers.

Progesterone secretion is crucial for maintaining pregnancy to parturition in mammalian species, and in cattle the corpus luteum is the primary source of this hormone. This study determined the roles of prolactin (PRL), growth hormone (GH) and luteinizing hormone (LH) in the luteotropic process in beef heifers hypophyseal stalk-transected (HST, n=7) or sham operated (sham operated controls, SOC, n=9) during midgestation. The main finding was that endogenous PRL and GH maintained progesterone secretion in HST heifers in a similar manner to that in SOC throughout pregnancy. Serum PRL averaged 37 vs 187 and GH 2 vs 4 ng/ml in HST heifers compared with SOC, whereas LH abruptly decreased to undetectable levels after HST compared with a modest 0.4 ng/ml in SOC heifers. The second finding was that parturition and lactation occurred in HST heifers with calf delivery induced to occur at the same time as SOC. Milk production in HST animals was severely limited, and postpartum estrus obliterated compared with SOC. The suckling stimulus sustained milk ejection in HST heifers in spite of diminished PRL, GH, thyroid stimulating hormone, thyroxine and tri-iodothyronine secretion. The results suggest that PRL, GH and possibly placental lactogen are luteotropic during pregnancy in cattle.

Animals↗
PubMed1995

Mifepristone (RU 486) induces parturition in primiparous beef heifers and reduces incidence of dystocia.

Crossbred beef heifers (n = 21) were artificially inseminated and on d 268 (expected parturition = d 283) heifers were fitted with an indwelling jugular catheter for sequential blood sampling from d 270 to 278. Heifers were assigned randomly to three treatment groups (n = 7) on d 277: Group 1 received the synthetic steroid mifepristone (RU 486) alone, Group 2 received RU 486 plus relaxin, and Group 3 received placebo treatment. Parturition occurred 43 h after treatment in Group 1, 52 h in Group 2, and 182 h in Group 3, and hormone treatment reduced treatment-to-calving interval compared with diluent treatment (P < .01). Calf birth weights were lower in hormone-treated than in placebo-treated heifers (P < .025), but all calves were vigorous at birth. The incidence of dystocia was lower (P < .05) in heifers in Groups 1 and 2 than in controls. Conversely, placental retention longer than 24 h was observed in hormone-treated heifers, and none occurred in the control group. The RU 486 reduced circulating progesterone concentrations in treated heifers, whereas progesterone concentration remained increased in control (P < .01). The results show that RU 486 alone or combined with relaxin induces delivery in late-pregnant heifers. Hormone treatment promotes calving ease with a markedly reduced incidence of the detrimental effects of dystocia, which may be a serious problem in first-calf heifers.

Animals↗
PubMed1980

Induction of parturition in the ewe.

One-hundred and seventeen ewes were used in a study of induction of parturition. Ewes were treated with either 2 mg flumethasone (FLU), 15 mg prostaglandin F2 alpha-THAM salt (PGF) or physiological saline (control) on day 141 of gestation, as determined by dates of marking by rams. Eighty-nine percent of the ewes treated with FLU and 33% of the ewes treated with PGF lambed within 72 hr post-treatment. More (P less than .01) ewes treated with PGF or FLU lambed within 72 hr than did control ewes. The interval from treatment to parturition was shorter in FLU (P less than .01) and PGF (P less than .05) treated ewes than in ewes given saline.

Animals↗
PubMed1986

Maternal behavior of beef cows at parturition.

Over an 11-yr period maternal behavior, calf birth weight and calf condition were recorded within 24 h for 2,684 parturitions. Maternal behavior was rated on a scale from 1 to 11, where 1 indicated extreme aggressiveness and 11 indicated no maternal attentiveness. Birth condition was rated on a scale from 1 to 9, with 9 being fattest and 1 thinnest. Respective breed means of Hereford, Angus, Charolais and Red POll were 6.2, 5.3, 6.0, and 5.7 for maternal behavior rating; 30.6, 27.3, 39.2 and 32.6 kg for birth weight, and 5.5, 4.7, 5.6 and 5.5 for birth condition. Heritability estimates for maternal rating, birth weight and birth condition were .06 +/- .01, .48 +/- .02 and .19 +/- .01, respectively. Genetic correlations between maternal rating and birth weight and condition were .04 +/- .05 and -.02 +/- .06, respectively. These results suggest that, in the population of cows studied, nongenetic influences were the primary cause of differences in aggressiveness of cows at parturition.

Aggression↗
PubMed1986

Inositol and hepatic lipidosis. II. Effect of inositol supplementation and time from parturition on serum insulin, thyroxine and triiodothyronine and their relationship to serum and liver lipids in dairy cows.

Percutaneous liver biopsies and blood samples were obtained from 80 dairy cows in nine Michigan herds over the peripartum period. Thirty-nine cows were fed 17 g of supplemental inositol and 41 were fed a placebo. Liver biopsies were assayed for total myoinositol and triglyceride (TG) concentrations. Blood samples were assayed for serum dextran precipitable cholesterol, nonesterified fatty acids (NEFA), insulin, thyroxine (T4), free (FT4), triiodothyronine (T3) and free T3 (FT3) concentrations. Serum concentrations of insulin and the thyroid hormones decreased near parturition, with lowest concentrations occurring in the immediate postpartum period. Concentrations of T3 correlated well with T4, and the concentrations of free thyroid hormones reflected concentrations of total thyroid hormones. The percentage of hormone in the free fraction remained constant over time. Serum insulin, T3 and T4 were negatively correlated with serum NEFA and liver TG concentrations. Thyroid hormone concentrations were positively correlated with serum dextran precipitable cholesterol concentrations. Inositol supplementation was associated with reduced circulating T3 and FT3 concentrations, but not T4 and FT4 concentrations. Changes in hormone concentrations at parturition and their relationship to liver TG and serum NEFA concentrations were consistent with a metabolic adaptation by the dairy cow to the negative energy balance of early lactation.

Animals↗
PubMed1987

Estrone concentration in sow milk during and after parturition.

Colostrum and milk samples were obtained from five Yorkshire gilts through manual expression of glands at the onset of parturition; at 1, 2, 4 and 8 h after birth of the first piglet and at 8-h intervals thereafter until 96 h. Oxytocin (30 units) was used to stimulate milk ejection for all samples except during parturition. Samples were frozen until subjected to a validated radioimmunoassay for estrone (E1). In a preliminary study no differences existed in concentrations of E1 among various glands. Therefore, mean of values obtained from three randomly selected glands was used for analysis in the main trial. Concentration of E1 at birth averaged 13.6 +/- 1.78 ng/ml (X +/- SE), and decreased to 6.05 +/- .80, 3.12 +/- .60, 1.42 +/- .30, .69 +/- .20 and .33 +/- .92 ng/ml at 4, 8, 16, 32 and 96 h, respectively. The postpartum decrease in the concentration of E1 in the milk is most likely due to the loss of the placental source.

Animals↗
PubMed1988

Effects of induced parturition and early obstetrical assistance in beef cattle.

Pregnant crossbred beef females (33 second-calf cows and 73 primiparous heifers) bred to a single Hereford sire were assigned to a 2(3) factorial study involving age of dam, natural (NP) or induced (IP) parturition and late emergency (LA) or forced early (EA) obstetrical assistance. Parturition was induced with 10 mg flumethazone given i.m. between 1400 and 1600 on d 272 of gestation; EA was given when the cervix and birth canal were fully dilated. Average IP occurred 39.6 h postinjection, and 95.3% of the treated dams responded within 60 h postinjection; gestation was shortened 2.9 d (P approximately equal to .07). Dystocia score (from 1 = no assist to 4 = major traction required and 5 = abnormal presentation) was 1.12 vs 2.40 for LA and EA, respectively (P less than .01), and 11% of LA vs 84% of EA were assisted. Calf vigor score (1 = normal to 3 = severely depressed or dying) at birth was 1.3 for NP and 1.1 for IP (P approximately equal to .06) and 1.3 for EA and 1.1 for LA (P less than .05). This effect of EA was due to reduced vigor of calves experiencing abnormal presentation. Birth weights (BW) and weaning weights (WW) of calves from cows exceeded those from heifers (32.6 vs 30.8 kg, P less than .05; 210.9 vs 156.3 kg, P less than .01, respectively). Differences due to IP and EA in BW, WW, postpartum interval and conception rate were not significant, but weight gain of calves from EA dams tended (P approximately equal to .09) to be greater than weight gain of calves from LA dams.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Fibrinopeptide A and intravascular coagulation in normotensive and hypertensive pregnancy and parturition.

Fibrinopeptide A (FpA), fibrin monomers, fibrinogen, fibrin degradation products (FDP) aand platelets have been studied during pregnancy, parturition and during toxemia and compared with normal non-pregnant controls in order to evaluate thrombin activity under these conditions. We found a significant rise in fibrinopeptide A levels in late pregnancy and even more so during parturition with a maximum immediately after placental expulsion. We also found elevated FpA levels in toxemic patients, but no significant differences from normal pregnancies. Fibrin monomers were more often elevated during delivery and toxemia during normal pregnancy. One case report concerning a patient with deficient thrombin activation and heavy postpartum bleeding is added. Our studies indicate an increased thrombin activity and fibrinogen turnover in both normal and toxemic pregnancies. During normal childbirth, coagulation activity seemed to reach a maximum immediately after placental separation.

Adult↗
PubMed1984

Causes and consequences of maternal and fetal sympathoadrenal activation during parturition.

The sympathoadrenal system is activated in both the mother and fetus during parturition. The fetal plasma catecholamines may reach extremely high levels during deliveries complicated by asphyxia. Increased maternal sympathoadrenal activity during labour or caesarean section may negatively affect uteroplacental blood flow with possible adverse effects on the fetus. Such an increase may be avoided by adequate maternal pain relief and by the sympathetic blockade which follows epidural anaesthesia. Fetal sympathoadrenal activation during parturition seems on the contrary to be of positive functional importance both for fetal circulatory regulation in utero a well as for the neonatal adaptation in terms of pulmonary function and metabolic stimulation.

Adrenal Glands↗
PubMed1998

The role of prostaglandins in human parturition.

Parturition is the process of giving birth, and the molecular mechanisms involved are still to be elucidated. Among the various factors involved prostaglandins appear to have an important role. They are synthesized within the human fetal membranes (amnion and chorion) and decidua and act to ripen the cervix, change membrane structure and contract the myometrium. Prostaglandin concentrations increase in amniotic fluid prior to myometrial contractions, and the activity of prostaglandin H synthase (PGHS) increases in the chorion laeve and amnion at labour. This increase is due to increased expression of the PGHS-2 isoenzyme rather than the PGHS-1 isoenzyme. In animal pregnancy, there is also an increase in the expression of the PGHS-2 isoenzyme, and in both human and animal pregnancies this increase appears to occur in the fetal tissues rather than in the maternal tissues. Prostaglandin metabolism also plays an important role in altering prostaglandin output by the human fetal membranes. Prostaglandin dehydrogenase (PGDH) activity decreases in certain cases of preterm labour, and at term it decreases in the area of the chorion laeve covering the cervix. This may allow active prostaglandins produced by the amnion and chorion to access the cervix and myometrium. Recent studies have indicated that glucocorticoids may be important in regulating prostaglandin formation within the human fetal membranes by increasing expression of PGHS-2 in the amnion and decreasing PGDH activity in the chorion. Prostaglandin formation is also important in infection-induced preterm labour and both phospholipase and PGHS-2 activities can be increased by various cytokines. Prostaglandins are important for the onset of both term and preterm parturition and their effects may result from changes in prostaglandin synthesis, prostaglandin metabolism and expression of various prostaglandin receptors.

Animals↗
PubMed1998

Cytokines in preterm parturition.

We have proposed a model in which the initiation of human parturition in the presence of infection is mediated by the host response. Systemic infections such as pyelonephritis, or localized intrauterine maternal infections such as deciduitis and cervicitis, might trigger parturition via the monocyte/macrophage system in both maternal blood and human decidua. According to this model, labor is to be considered an event that occurs when the intrauterine or maternal environment is hostile to the well-being of the fetus, as was supported by recent studies. From this point of view, the initiation of preterm labor may have survival value.

Cytokines↗
PubMed1976

Calcium redistribution into subcutaneous fat at parturition in the dairy cow.

Blood samples and subcutaneous fat biopsies from six dairy cows at -14, 0, 14, and 28 days of parturition were analyzed to test the hypothesis that movement of calcium into subcutaneous fat contributes to hypocalcemia of parturient paresis. Plasma and subcutaneous fat calcium decreased while plasma free fatty acids increased at parturition. No trends were significant in magnesium or total lipid content of subcutaneous fat. Calcium content of subcutaneous fat was related positively to calcium concentration in plasma.

Adipose Tissue↗
PubMed1984

Biochemical and antibacterial properties of bovine mammary secretion during mammary involution and at parturition.

Mammary secretions from four Holstein Friesian cows were collected during late lactation, early involution, and early in subsequent lactation. Changes of pH, concentration of serum albumin, immunoglobulin G, citrate, lactoferrin, and number of leukocytes in secretions were typical of milk from glands undergoing these physiological transitions. Whey prepared from a cow's secretions was evaluated for its capacity to inhibit growth of Escherichia coli, 60-Lilly, and a coliform strain isolated from mammary secretions of that cow. Wheys from different glands of the same cow differed markedly in their capacity to inhibit growth of coliforms. Inhibition of both strains by the wheys increased significantly during the dry period and was maximal in wheys collected day 15 of the dry period and at parturition in the subsequent lactation. The coliform strain isolated from a specific cow was inhibited more than Escherichia coli, 60-Lilly, by whey from the specific cow. Inhibition of the cow-specific coliform strain by the day 15 whey was reduced significantly after addition of ferric iron or sodium citrate. Addition of excess ferric iron or citrate to wheys collected at parturition did not alter significantly their inhibitory capacity within cow. However, reduction of growth inhibition was significant when data from the four cows were pooled.

Animals↗
PubMed1996

Effects of fenprostalene and estradiol-17 beta benzoate on parturition and retained placenta in dairy cows and heifers.

It was hypothesized that a high dose of estrogen in conjunction with a long-acting PGF2 alpha analog would synchronize parturition within a narrow time frame and reduce the incidence of retained placenta. On d 276 of gestation, 14 animals (9 cows and 5 heifers) per group received a placebo (group A), 1 mg of fenprostalene (group B), 50 mg of estradiol-17 beta benzoate (group C), or both (group D). Treatment with estradiol-17 beta benzoate increased serum concentrations of estradiol-17 beta from 228 pg/ml at treatment to 642 and 683 pg/ml at 24 h posttreatment for groups C and D, respectively. Concentration of estradiol-17 beta in group A increased gradually to 526 pg/ml at 24 h prepartum. Progesterone concentrations were reduced by fenprostalene but not by estradiol-17 beta benzoate. Estradiol-17 beta benzoate did not reduce incidence of retained placenta in animals treated with fenprostalene (group B vs. group D) but tended to reduce incidence in uninduced animals (group A vs. group C). Thus, short-term elevation of estradiol-17 beta to normal prepartum concentrations did not regress the corpus luteum, induce parturition, or reduce incidence of retained placenta. However, elevation of estradiol-17 beta for longer periods might enhance placental separation. Conversely, fenprostalene induced calving approximately 2 d after treatment. In this study, 90% of animals treated with fenprostalene calved within a 20-h period, but with a high incidence of retained placenta.

Animals↗