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PubMed1985

Central opioids: a possible role in parturition?

Pregnant rats were implanted with subcutaneous minipumps to deliver either naloxone or saline. The time-course of subsequent parturition was different between the two groups: the interval between successive births was significantly shorter for the naloxone-treated rats. This supports the hypothesis that the opioid innervation of the neurohypophysis, which is known to influence oxytocin release profoundly, has a physiological role in parturition. To test the further hypothesis that this role is particularly important in a stressful environment, pregnant rats, again implanted with minipumps, were regularly transferred, at 15-min intervals beginning with the birth of the first pup, between their normal cage and the unfamiliar environment of a glass observation chamber. No difference was noted between the time-courses of parturition for the naloxone- and saline-treated groups, although the time-courses were markedly altered from those observed in rats not subjected to an unfamiliar environment. We conclude that opioid modulation of oxytocin release may play a role in 'spacing' the delivery of successive births during normal parturition.

Animals↗
PubMed1989

Ablation of the region anterior and ventral to the third ventricle (AV3V region) does not impede parturition in rats.

The region anterior and ventral to the third ventricle (AV3V) region is a major source of excitatory afferents to the magnocellular neuroendocrine system, and is essential for the osmotically regulated release of oxytocin. We investigated whether this input has a similarly essential role in parturition. Rats were implanted with a guide cannula in the AV3V region on days 9-18 of pregnancy. Following the birth of the third pup, rats were anaesthetized briefly with ether and either given an electrolytic AV3V lesion or a sham procedure was carried out. In eight AV3V-lesioned rats the mean (+/- S.E.M.) median interbirth interval following the lesion was 6.3 +/- 1.2 min compared with 5.2 +/- 0.6 min in 11 sham-lesioned rats. All rats completed delivery of their litters. The mean plasma concentration of oxytocin was unchanged following the sham procedure (pre-sham 17.1 +/- 2.8 pmol/l, n = 8; 15 min post-sham 18.1 +/- 2.7 pmol/l, n = 8; 30 min post-sham 19.2 +/- 3.5 pmol/l, n = 8). In AV3V-lesioned rats, plasma oxytocin was significantly raised following the lesion (pre-lesion 14.6 +/- 1.3 pmol/l, n = 7; post-lesion 58.3 +/- 9.8 pmol/l, n = 7) and was still higher than the sham-treated group after 30 min (55.8 +/- 9.9 pmol/l). Thus there was no significant difference in the time-course of parturition between AV3V-lesioned rats and sham-lesioned rats, and no evidence that the lesion impaired the release of oxytocin. Furthermore, in rats given an AV3V lesion on the morning of the expected day of delivery, parturition was neither delayed nor disrupted, suggesting that the AV3V region does not contribute to the mechanisms controlling the onset of parturition.

Animals↗
PubMed1992

Ponderosa pine needle-induced parturition in cattle.

Needles of the Ponderosa pine (Pinus ponderosa) induce premature parturition in cattle when ingested during late pregnancy, especially during the third trimester. The closer to term, the more likely that pine needles will induce parturition. Experiments were designed to describe the clinical signs and behavior associated with ingestion of pine needles. Pine needles adversely affected only pregnant cows and did not seem to affect nonpregnant, cycling cows, sheep, goats, or rabbits. Premature parturition was more likely if cows ingested the needles after the 8th mo of pregnancy, if they ingested pine needles over a period of 3 d or more, and if cows ate a relatively large amount of pine needles (about 2.2 to 2.7 kg/d). A synthetic progesterone, melangesterol acetate, and a prostaglandin inhibitor (ketoprofen) seemed to be of some prophylactic benefit; however, further research is required to assess the practicality of the approach and the magnitude of the benefit. Ponderosa pine bark and new-growth branch tips, which seem to be more potent inducers of premature parturition, may be useful in the extraction and identification of the parturifacient component(s).

Animals↗
PubMed1995

Reproductive responses and calf birth and weaning weights as affected by body condition at parturition and postpartum weight gain in primiparous beef cows.

Effects of body condition score (BCS) at parturition and postpartum weight gain on reproduction and production responses were evaluated using 240 primiparous (21 to 28 mo) beef cows calving in 60-d periods in three states over 3 yr. Cows were randomly allotted 90 d before parturition and fed to achieve BCS of 4, 5, or 6 (1 = emaciated, 9 = obese) at parturition. After parturition, one-half of these cows (within state) were group-fed to gain .45 kg/d (moderate) or .90 kg/d (high) until the start of a 60-d breeding season. Cows calving in BCS of 4, 5, or 6, respectively, had calves with progressively heavier (P < .05) birth weights, but dystocia score was not influenced by BCS at calving. Parturient BCS of cows had no effect on actual or 205-d adjusted weaning weights of calves. Birth weights, dystocia score, and actual and 205-d adjusted weaning weights were affected by location (P < .05). Cows with greater weight gains postpartum had calves with heavier (P < .05) actual and 205-d adjusted weaning weights than did cows with moderate weight gains. No significant interactions among location, BCS, or postpartum nutrition-group were observed for any of the production variables described above. Greater BCS at calving resulted in more (P < .05) cows in estrus and more (P < .05) cows pregnant by 40 and 60 d of a breeding season. Luteal activity by start of breeding, as well as estrus responses and pregnancy rates at 20, 40, or 60 d of a breeding season, were affected by location (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Porcine LH levels during the estrous cycle, gestation, parturition and early lactation.

Thirty-five sows were used in a study of plasma luteinizing hormone (LH) concentrations during the estrous cycle, including first and second estrus postweaning, during gestation, at parturition and during the first 5 d of lactation. After cannulation of the anterior vena cava via the cephalic vein, blood samples were collected four times daily for 2 d before estrus, during estrus and for 3 d after estrus and once daily at 1100 h throughout the rest of the estrous cycle. One sample was collected from each sow on alternate days (1100 h) during the gestation period. Four daily samples were obtained on d 60 through 68 of gestation and for 5 d after parturition. Preovulatory surges of LH occurred 8 to 32 h before standing estrus in four of seven sows during first estrus and in three of seven sows during second estrus. The mean preovulatory LH surge during the first estrus postweaning (3.00 +/- .46 ng/ml) was lower than that during second estrus (4.24 +/- .60 ng/ml). Throughout the first 12 d of gestation, LH concentrations were relatively high and variable, ranging from 1.2 to 2 ng/ml. They then decreased to a range of .42 to .62 ng/ml after d 24. Similar LH concentrations were noted throughout the remainder of gestation except for some slight fluctuations. Higher concentrations (P less than .05) were noted with evening collections (1900 h, 1:17 +/- .09 ng/ml) than in daytime collections (0700 h, .64 +/- .08: 1100 h, .61 +/- .06; 1500 h, .72 +/- .06 ng/ml) during d 60 to 68 of gestation. Low plasma concentrations of LH (.3 to .5 ng/ml) were observed for the 5 d before and during parturition. After parturition, considerable variation of LH occurred, with rising concentrations observed on d 5 postpartum. Results of this study illustrate the occurrence of LH surges before behavioral estrus with increased plasma LH during implantation.

Animals↗
PubMed1983

Use of lambing cubicles and the behavior of ewes at parturition.

Three trials were conducted involving 393 ewes to determine the feasibility of using cubicles to provide isolation for parturient ewes in lambing pens. The cubicles consisted of an enclosure with 1 m high walls and a small (.6 m wide) opening to allow ewes free access. In trial 1, 42% of the parturitions occurred in the cubicles, which occupied only 19% of the pen area. No preference was noted for large (1.8 x 1.8 m) vs small (1.8 x 1.2 m) cubicles. Use of the cubicles increased from 4% of the time 24 h before parturition to 25% of the time during the 6 h immediately preceding parturition. In trial 2, ewes did not show a preference for open vs covered walls on cubicles or for open vs covered cubicle ceilings. Cubicles were again used to a greater (P less than .01) extent than would be predicted by their relative area (26% use, 18% area). In the final trial, mature ewes used cubicles to a greater (P less than .10) extent than did yearlings (55 vs 38%, respectively). Cubicles and areas of the pen farthest from the working area of the herdsman were most frequently (P less than .001) used during parturition. Cubicles appeared to be effective in preventing separation of newborn lambs from their dam and in reducing interference by other ewes.

Animals↗
PubMed1998

Reduction of acyloxyacyl hydrolase activity in circulating neutrophils from cows after parturition.

Bovine neutrophils contain the enzyme acyloxyacyl hydrolase, which hydrolyzes the acyloxyacyl linkage of the two nonhydroxylated fatty acyl chains to two 3-hydroxy fatty acids in the highly conserved lipid A part of endotoxins with high specificity. This hydrolysis decreases the toxicity of lipid A, but the immunostimulatory capacity of endotoxins is largely maintained. In two trials, we studied the activity of acyloxyacyl hydrolase in neutrophils that had been isolated from the blood of 18 dairy cows around parturition. Between 10 and 26 d after parturition, the activity of acyloxyacyl hydrolase in neutrophils decreased approximately 20% below prepartum activity. At about 2 mo after parturition, acyloxyacyl hydrolase activity returned to prepartum values. Changes in acyloxyacyl hydrolase activity could not be attributed to changes in binding of lipopolysaccharides by the CD14 molecules on neutrophils or monocytes. We hypothesize that decreased acyloxyacyl hydrolase activity in neutrophils shortly after parturition is a factor that increases the susceptibility of dairy cows to coliform mastitis during early lactation.

Animals↗
PubMed2000

Oxytocin release and its relationship to dihydro-15-keto PGF2alpha and arginine vasopressin release during parturition and to suckling in postpartum mares.

Pituitary blood was collected from the intercavernal sinus in five mares before and during parturition, and in nine mares immediately after parturition to investigate oxytocin patterns during parturition and early lactation, and to determine the relationship between oxytocin, prostaglandin and arginine vasopressin during parturition. In four mares in which sample collection began at least 6 h before rupture of the chorioallantois, a significant increase (P < 0.05) in PGF(2alpha) concentration was detected before a significant increase in oxytocin concentration. Cross-correlation analysis of log-transformed oxytocin and PGF(2alpha) concentrations revealed a significant correlation (P < 0.05) at a 6 min lag period, indicating that in the 2 h before delivery of the foal, an increase in prostaglandin was followed 6 min later by an increase in oxytocin. A significant effect of suckling on oxytocin release by the mare was detected in only two of nine mares, when oxytocin concentrations were evaluated 0-3 min after suckling. When foals were prevented from sucking for 1 h, by being either muzzled (n = 2) or separated from the mare (n = 2), there was no significant association between resumption of suckling and oxytocin release by the mare. The results of these studies show that: (i) oxytocin secretion from the maternal posterior pituitary gland begins before, or in association with, the onset of the second stage of labour, and that prostaglandin increases in the peripheral circulation before oxytocin release; and (ii) suckling is not significantly related to oxytocin release in mares.

Animals↗
PubMed1999

A Nest Box to Facilitate Excreta Collection From Mouse Dams Through Pregnancy, Parturition, and Lactation.

Standard metabolism cages are inadequate for collecting excreta from dams during parturition because newborn pups can fall through the grating into the excreta collection area and out of reach of the dam. A nest box was designed that facilitates excreta collection from mouse dams continuously housed in metabolism cages from conception, through parturition, and into lactation and provides a safe, warm environment for pups during their first week of life. The nest box was tested by using pregnant and lactating mice of two varieties of strain 129/SvJ, metallothionein-normal and metallothionein-knockout; non-pregnant mice were used as controls. Pregnant mice (with nest box) and non-pregnant mice (without nest box) each twice received a solution of 109CdCl2 by gavage. Dams with nest boxes fastidiously urinated and defecated outside the nest box. The percentage of gavage 109Cd dose recovered in dam feces was the same after the first gavage (mean6SE, with nest box through parturition, 95%66%; n=5) as after the second gavage (mean6SE, without nest box, 95%66%; n=5). Weights and percentage weight gain of mouse dams were independent of housing conditions (metabolic cage with next box vs. conventional polycarbonate caging). Furthermore, pup growth and survival were unaffected by the inclusion of the nest box or by its removal at 1 week after birth. Therefore, the described nest box provides for the first time a way to quantitatively collect excreta from mouse dams through pregnancy, parturition, and the early postnatal period. Additional experiments are needed to test its application to other animal species and strains of mice, including those with poor mothering behavior.

Journal Article↗
PubMed2002

Follistatin concentrations in maternal and fetal fluids during the oestrous cycle, gestation and parturition in Merino sheep.

The aim of this study was to investigate the changes in follistatin, an activin binding protein, during the oestrous cycle, gestation and parturition in ewes using a radioimmunoassay for total follistatin, which uses dissociating reagents to remove the interference of activin. Follistatin concentrations remained unchanged (2.7 +/- 0.2 ng ml(-1)) during the oestrous cycle and decreased as pregnancy progressed. Follistatin concentrations in allantoic fluid also decreased during gestation, whereas in amniotic fluid follistatin concentrations reached a peak at day 75 of gestation (9.8 ng ml(-1)) and had decreased to 4.4 ng ml(-1) at day 140. Follistatin concentrations in fetal blood (7.0 +/- 0.5 ng ml(-1)) did not change from day 50 to day 140 of gestation but were significantly higher than in matched maternal samples (3.1 +/- 0.3 ng ml(-1)). Circulating follistatin in ewes was significantly increased on the day of parturition (5.6 +/- 0.6 ng ml(-1)) compared with the days before parturition (2.7 +/- 0.4 ng ml(-1)), but had decreased by day 2 after birth. Blood samples from newborn lambs showed that plasma follistatin concentration (13.4 +/- 2.3 ng ml(-1)) was significantly higher than that of the mothers and remained high for at least 7 days after birth. These data support previous studies of the human menstrual cycle indicating that follistatin is not an endocrine signal from the ovary; however, in contrast to human pregnancies, follistatin concentrations in sheep decreased and become high only after or during parturition. This difference observed between species may reflect different physiological effects of follistatin or may be the result of measurement of different isoforms.

Activins↗
PubMed1991

[Microscopic changes in intercaruncular endometrium and ovarian follicles in cows 35 days after parturition].

Surface epithelium of intercaruncular endometrium in pluriparous cows, crossbreds of Bohemian Pied cattle with Holstein-Friesian cattle, was not coherent until day 15 after parturition, with a variable height of cells (16-64 microns). Oedematous nature of lamina propria was subsiding gradually. From day 15 to day 20 after parturition the cell height of coherent surface epithelium and uterine glands became equable and stabilized (16-32 microns), and the lamina propria assumed its cellular nature with marked infiltration of polymorphonuclears and lymphocytes. Noticeable symptoms of atresia were demonstrated to occur more frequently in ovaries in the follicular population until day 15 after parturition. From day 10 to day 25 after parturition an increasing occurrence of luteinized follicles with diameters of maximally 3 mm was demonstrated.

Animals↗
PubMed1990

[Levels of toxic elements--Cd, Pb, Hg, Cr, Cu, Zn--in the blood and placenta of cows during parturition and in newborn calves].

It was demonstrated that mother's blood and the blood of new-born calves were contaminated by toxic elements in exposed and non-exposed area. The average Cd and Zn levels differed at high statistical significance (P less than 0.01) in the mothers blood from non-exposed regions in comparison with the average Cd and Zn levels from exposed region. The average residues of toxic elements in breeding cows placenta from the exposed and non-exposed regions were not statistically different. The average Zn content in new-born calves from non-exposed regions differ highly statistically significantly in comparison with the average Zn content in the blood of new-born calves from heifers of the exposed region. The transplacental ratio (TPx) of a toxic element in cow placenta during parturition was expressed from the average ratio of toxic element content in mother's blood: toxic element content in placenta: the toxic element content in blood of newborn calf, while the content of toxic element in mother's blood during parturition was expressed by a value equal to one. TPx in parturition period was expressed by mathematical formula TPx = 1 : Xp : Xk, where Xp = toxic element content in placenta, Xk = content of the toxic element in blood of new-born calf. TPPb, Hg, Cr, Cu, Zn values were not statistically different between the groups of breeding cows from exposed and non-exposed regions. TPCd in the group comprising 14 first-calves from the exposed region (TPCd = 1:0.89:2.59 in comparison with TPCd of six cows from non-exposed region, where TPCd = 1:0.29: 0.70;, differed statistically highly significantly (P less than .01). High statistical differences (P, less than 01) TPCd between these groups were explicitly affected highly statistically significantly (P less than .01) by different average Cd content in the blood of fourteen first-calves, compared with the average Cd content in blood of six cows from non-exposed region, in which the Cd value in blood during parturition was higher by 10(-1).

Animals↗
PubMed1990

Use of dexamethasone for induction of parturition in goats.

Parturition was induced in 5 goats of Beetal and Beetal x Black Bengal cross in advanced stages of pregnancy, using intramuscular injection of 10 mg of dexamethasone. Goats required 47.7 +/- 1.26 hours on average after injection for parturition. There were no deleterious effects of induction on placental expulsion, kid weight, kid survival, and postpartum fertility of does. Plasma concentrations of progesterone and oestradiol 17 beta followed a similar trend in controls and treated animals. While plasma progesterone concentrations declined before parturition, the oestradiol concentration rose to its peak on the day of parturition.

Animals↗
PubMed1988

[Changes in the innervation of the uterus during pregnancy and following parturition. Histochemical and electron microscopic observations in rat and humans].

A histochemical, electronmicroscopic study was made of time changes in uterine nerves during and after pregnancy in rats. Uterine observations in pregnant humans were also conducted with the following results. 1. Except at the oviductal end, the catecholamine (CA) fluorescence of adrenergic nerves distributed in the uterine horn myometrium begins to decrease around the implantation sites, and this spreads peripherally until most of the fluorescence in the uterine horns, including the mesometrium, disappears directly after parturition. 2. In lactating rats, fluorescence is almost completely restored by 1 month after parturition. But in non-lactating rats, recovery of fluorescence after parturition is delayed about 3 months. 3. The activity of acetylcholinesterase (AChE) in rat uterine cholinergic nerves clearly decreased during pregnancy. 4. In the early, middle and late periods of pregnancy, axonal swelling, agglutination of axonal cytoplasm and mitochondrial breakdown were observed, but no marked degeneration appeared in virgin rat uteri. 5. In humans, there was a sporadic distribution of adrenergic nerves in the uterine body myometrium, but fluorescent fibers were present in the terminal period of pregnancy. These results suggest that rat uterine nerves, especially most adrenergic nerves, degenerate and regenerate throughout pregnancy, parturition and puerperium. Apparently a localized humoral factor from the placenta and systemic endocrine environment affected by lactation or non-lactation is involved in the process.

Adrenergic Fibers↗
PubMed1979

[Hormonal situation on parturition, early puerperium, and lactation (author's transl)].

Variations of the 17-beta oestradiol, progesterone, and prolactin levels in the serum were studied in the context of ten spontaneous parturitions. All cases were investigated within the first five puerperal days, but in five cases additional checks were undertaken over the first four weeks of the puerperium. Milk secretion was measured, as well. The oestradiol and progesterone titres were found to remain below the level common toward the end of pregnancy. They dropped rapidly after parturition and remained low throughout the puerperium. Prolactin underwent slight variation on parturition, but it actually stayed at the high level measurable at full term. Parturition was followed by brief temporary rise and, again, by decline, but values remained above those of non-pregnant women throughout puerperium. Milk production increased gradually over the first five days and remained similarly high throughout several weeks, accompanied by accordingly high prolactin levels. No absolute correlation was found to exist between the extent of lactation and the prolactin level. The presence of a relationship between oestradiol and progesterone levels, on the one hand, and lactation, on the other, cannot be assumed with probability.

Estradiol↗
PubMed1984

Pre-parturitional changes in serum prolactin, placental lactogen, growth hormone, progesterone, and corticosterone in the C3H/HeN mouse.

Pre-parturitional changes in serum prolactin, placental lactogen, growth hormone, progesterone, and corticosterone in the C3H/HeN mouse are described. Serum prolactin concentrations display an apparent biphasic pre-parturitional increase. Both serum placental lactogen and growth hormone concentrations are elevated during the second half of pregnancy. Serum placental lactogen concentrations remain elevated until parturition, whereas serum growth hormone concentrations decline on the last two days of pregnancy. Serum progesterone and corticosterone concentrations are elevated during the latter half of pregnancy and decline on the day preceding parturition.

Animals↗
PubMed1980

[Quantitative morphological studies of effects of pregnancy, parturition and lactation on omental milk spots in the mouse (author's transl)].

Effects of pregnancy, parturition and lactation on milk spots of the mouse were quantitative-morphologically examined. In the mouse, as reported previously, omental milk spots were morphologically classified into two types; type I and type II. Type I milk spots, which are seen along the perivascular fatty tissue around the omental vessels, are increased in size at the end of pregnancy and show significant enlargement after parturition. They are developed remarkably in lactating mice, and moderately in non-lactating mice. Type II milk spots, which are scattered throughout the omentum, are increased at parturition and remain well developed both in lactating and non-lactating mice. In the mesentery, milk spots normally are not observed. However, type II milk spots appear at the end of pregnancy. They increase after parturition, especially in non-lactating mice. In addition, type I milk spots are sometimes seen in the mesentery of non-lactating mice.

Animals↗
PubMed1980

Induced parturition in cattle. II. Plasma oestrogen and progesterone levels.

Plasma oestrogen and progesterone levels were determined in cattle at the time of dexamethasone induced parturition. Oestrogen levels were elevated from the day after dexamethasone administration as well as on the day of parturition but declined rapidly to low levels on the day following parturition. Progesterone levels showed a decrease from the day of dexamethasone administration until parturition with a rapid drop to very low levels on the day following calving. These results are similar to those reported by other workers.

Animals↗