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At least 19 recordsLinked to original sources
PubMed1977

Parturition in goats: studies on the interactions between the foetus, placenta, prostaglandin F and progesterone before parturition, at term or at parturition induced prematurely by corticotrophin infusion of the foetus.

Relationships between foetal corticosteroid concentrations, utero-ovarian prostaglandin F (PGF) and maternal peripheral progesterone have been examined in detail in goats shortly before spontaneous parturition at term. Foetal corticosteroids increased during the last 13-11 days of gestation and particularly sharply during the last 3 days and even during advanced labour. About 24 h before parturition, acute releases of PGF were evident in the vein draining the pregnant uterine horn, and these corresponded closely to the time of luteal regression. Further release of PGF occured when progesterone declined to low levels, probably reflecting in the course of labour. The changes observed before premature parturition, induced by infusing ACTH into foetal goats, were similar except for the more rapid increase in foetal corticosteoid concentrations. Immature neonates born after ACTH treatment were viable, placental delivery was normal and lactogenesis occurred in the mothers indicating that the treatment promoted full expression of the critical perinatal events. The early, acute releases of PGF were ipsilateral to the ACTH-infused foetus and were luteolytic provided the corpora lutea were also on that side. Luteolysis failed or was abnormally delayed if the corpora lutea were contralateral and prolonged ACTH treatment of the foetuses in such cases caused foetal death probably because of premature failure of the placenta. Similar findings were noted if ACTH infusion of the foetus was accompanied by simultaneous progesterone treatment of the mothers in order block the induction of labour. It was suggested that placental changes occurring during foetal hypercortisolism might be caused by increased placental oestrogen synthesis and the effect of this on the foeto-maternal junction along with a stimulatory action on PG synthesis in the maternal placenta. Experimental disruption of the normal sequence of events, when labour was blocked by progesterone, proved to be lethal to the foetus if the loss of placental integrity progressed sufficiently. The chain of regulatory signals linking increased activity of the foetal adrenal with parturition thus appears to involve stimulation of oestrogen biosynthesis, PGF release from the maternal placenta and the start of physical changes at the placental junction. Provided the foetus and corpora lutea are ipsilateral, the early releases of PGF effect luteolysis and a withdrawal of progesterone from the maternal circulation. When progesterone concentrations are sufficiently low, labour is initiated and its progress reflected by further release of PGF. The control mechanisms, which also provide for the final maturation of the foetus, clearly enable a close synchronization of the various perinatal events which are essential for the transition from foetal to postnatal life.

Adrenal Cortex Hormones↗
PubMed1996

Event-time analysis of the effect of season of parturition, parity, and concurrent disease on parturition-to-conception interval in dairy cows.

OBJECTIVE: To quantify the effect of season of parturition, parity, and various diseases on time to conception. DESIGN: Event-time analysis (survival analysis). SAMPLE POPULATION: 44,450 cows delivering calves between September 1985 and September 1986, from 6,227 Ayrshire dairy herds in 80 Finnish communities. PROCEDURES: Primiparous and multiparous cows were analyzed in separate Cox proportional hazards models for postpartum days 56 to 120. Occurrence of 43 diseases or disorders was recorded; codes were condensed into 25 variables offered to each model. Season of parturition was categorized into spring, summer, and fall-winter; for multiparous cows, 3 categorical variables represented parity. Models controlled for 60-day milk and milk fat production, herd milk production, and community. For all observations, parturition-to-conception interval was plotted against calendar day of parturition. RESULTS: For multiparous cows, parturition in the spring or summer and being of parity 2 or 3-4 (vs older) increased the chance of conceiving; 10 diseases or disorders decreased this probability. Similarly, in the model for primiparae, parturition in spring or summer increased the probability of conception, and 6 disorders decreased it. Disorders that were detrimental in both models were anestrus, ovulatory dysfunction, other infertility, late metritis, and clinical ketosis. CONCLUSIONS: The effect of season on the parturition-to-conception interval was marked at this latitude. Parturition during late April, causing confluence of postpartum day 55 with the summer solstice, was associated with the shortest parturition-to-conception intervals. Ketosis was found to be an important factor in lengthening the parturition-to-conception interval, highlighting the effect of negative energy balance on postpartum restoration of reproductive function.

Animals↗
PubMed2003

Role of prostaglandin H2 synthase 2 in murine parturition: study on ovariectomy-induced parturition in prostaglandin F receptor-deficient mice.

To determine the prostaglandin (PG) H2 synthase (generally referred to as cyclooxygenase [COX]) isozyme responsible for producing uterotonic PGs during parturition, we used PGF2alpha receptor-deficient mice, which exhibit parturition failure due to impaired withdrawal of serum progesterone at term. On ovariectomy-induced parturition in these mice, uterine COX-2 mRNA expression was drastically induced in the myometrium, whereas COX-1 mRNA expression in the endometrial epithelium decreased. The concomitant administration of progesterone with ovariectomy resulted in a delay in parturition and the disappearance of both the increase in COX-2 mRNA and the decrease in COX-1 mRNA. Thus, the expression of myometrial COX-2 and the occurrence of parturition are closely associated in this model. Furthermore, administration of the COX-nonselective inhibitor, indomethacin, or the COX-2-selective inhibitor, Dup-697 or JTE-522, effectively delayed ovariectomy-induced parturition in these mice. These findings suggest that COX-2-derived PGs contribute to the onset of parturition after the decrease in serum progesterone level.

Animals↗
PubMed1979

[Control of parturition in swine. 2. Study results of parturition synchronization in swine with the prostaglandin analog cloprostenol (I.C.I. 80.996: Estrumate)].

Premature parturition was induced in 115 of 121 sows (95%) that had been given injections of 150 microgram or 200 microgram of "Estrumate", a prostaglandin analogues, on the 112th and 113th days of gestation. The average time that elapsed between injection and parturition of those 115 animals was 27.2 +/- 7.7 hours, with no difference being observed between gilts, on the one hand, and old sows, on the other. The time of gestation of the treated animals was shortened with significance from 114.6 +/- 1.6 days for the controls to 113.2 +/- 0.4 days. The average duration of parturition proper was 3.7 +/- 2.2 hours, the average litter being 11.2 +/- 3.3 piglets. The total number of piglets born was 1,320, with stillbirths accounting for 4.17%. The average weight at birth, 1,330 +/- 210 g, and the weight at weaning did not differ from weight figures recorded from the controls. The courses of parturition and puerperium were in agreement with normal biological standards. The sows treated were tested for their blood counts close to full term and for their endometrial histomorphology after weaning, with no side effects of "Estrumate" treatment being established. The behaviours of progesterone, 17-beta oestradiol, and cortisol in serum of "Estrumate"-treated sows were investigated, and congruence was established between spontaneous and prostaglandin-induced parturitions, which was in agreement with international literature. The conclusion is that 150 micrograms of 'Estrumate", administered to swine, after the 11th day of gestation has very good labour-inducing effects and ensures normal physiological parturition and piglet development.

Animals↗
PubMed2002

Serum lipid profile in Iranian fat-tailed sheep in late pregnancy, at parturition and during the post-parturition period.

Blood samples were obtained from 12 Iranian fat-tailed sheep during 7 weeks pre-partum, at parturition and 7 weeks post-partum. The lipids measured were cholesterol, triglyceride, total lipid, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, and very low-density lipoprotein (VLDL)-cholesterol. The concentrations of cholesterol, triglyceride, HDL-cholesterol and VLDL-cholesterol during the 7 weeks pre-partum, at parturition and the 7 weeks post-partum were significantly different (P < 0.05). One week before parturition, the concentrations of cholesterol, triglyceride, HDL-cholesterol and VLDL-cholesterol were higher (P < 0.05) than at other periods. The lowest concentrations of these parameters were observed 2-3 weeks after parturition. In this study, significant positive correlations were observed between the time of sampling (pre-partum, parturition and post-partum) and serum cholesterol (r = 0.22; P < 0.01) and HDL-cholesterol (r = 0.25; P < 0.01).

Animals↗
PubMed1990

Initiation of parturition and lactation in the sow: effects of delaying parturition with medroxyprogesterone acetate.

The synthetic progestagen, medroxyprogesterone acetate (MPA), was administered to sows in late pregnancy with the objective of slightly delaying the time of farrowing and thereby providing more marked associations between hormonal changes and the termination of pregnancy, and the initiation of farrowing and lactation in this species. MPA was administered orally (140 mg, twice daily) to eight sows in late pregnancy on days 112, 113 and 114 of gestation. Parturition was then induced to occur on day 116 by injecting 200 micrograms cloprostenol i.m. on day 115 of gestation. The peripartum changes in the plasma concentrations of progesterone, cortisol, oestradiol-17 beta, relaxin, prolactin, lactose and 13,14-dihydro-15-keto prostaglandin F2 alpha (PGFM) were measured in these sows together with a group of untreated sows. The gestational length for the MPA-treated sows (116.3 +/- 0.3 days, mean +/- S.E.M.) was significantly (P less than 0.01) greater compared with the untreated sows (114.9 +/- 0.3 days). Plasma progesterone declined earlier (P less than 0.05) with respect to the time of parturition in the treated sows compared with the untreated group. With respect to the timing of parturition, the time at which maximal concentrations of relaxin were attained and the timing of the subsequent decline were earlier in the MPA-treated sows. In both groups of sows, the concentration of relaxin increased before the decline in plasma progesterone. In the untreated sows, the concentration of PGFM increased either slightly before or at the same time as the decline in plasma progesterone, whereas in sows treated with MPA, progesterone concentrations began to decline before any significant increase in the plasma concentration of PGFM. The profiles of cortisol, oestradiol-17 beta and PGFM were similar in both groups of sows. In both groups of sows, the timing of the initial increase in the concentration of plasma prolactin coincided with a similar rise in plasma lactose (P less than 0.01). Plasma progesterone either declined earlier or at the same time as the rise in plasma lactose (P less than 0.01) in the treated group of sows only. We conclude that since the prepartum changes in the concentration of progesterone and relaxin occurred before significant changes in the concentration of PGFM in the MPA-treated sows, the nature of the luteolytic factor and the mechanism by which it exerts its action remains obscure. The higher concentration of lactose in the mammary secretion at birth in the MPA-treated sows compared with the untreated group suggested that lactogenesis was initiated earlier with respect to parturition following MPA treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

[Control of swine parturition. 1. Results of clinical, histological and hematological studies of parturition induction in swine using prostaglandin F2 alpha].

Parturition was induced to 23 sows on the 112th day of pregnancy by intramuscular injection of 7.5 mg PGF2 alpha (Dinoprost-Upjohn Co.). Onset of parturition was achieved within 27 hours and 52 minutes +/- four hours and 54 minutes in 21 animals (91.3 per cent). Average litter size was 11.33 piglets, with parturition time per litter having been five hours and 45 minutes +/- two hours and 39 minutes. Stillbirths accounted for 6.3 per cent. The average birth weight, 1.245 g +/- 264 g did not differ with significance from that of the controls. The physiological process accompanying parturition is described in greater detail. Unobstructed re-intergration with further reproduction of animals which had received PGF2 alpha treatment is established with hard evidence on the basis of clinical examination of oestrus, ovulation, conception, and farrowing rates as well as by histological examination of the endometrium. Alterations in the blood state recorded from animals with PGF2 alpha treatment close to full term were identical with those recorded from untreated animals.

Animal Husbandry↗
PubMed1988

The effect of luteinizing hormone on parturition in rats; imidazole antifungals may affect parturition via luteinizing hormone.

Studies were carried out to investigate the mechanism whereby the imidazole anti-fungal, tioconazole, affects parturition in rats. Administration s.c. of luteinizing hormone (LH) to pregnant rats on days 15-17 post-insemination (p.i.) or days 15-21 p.i. delayed the onset of parturition by a day and markedly reduced the ovarian production of 17 beta-estradiol, but not of progesterone. Administration of LH on days 18 and 19 p.i., which was already known to advance birth, reduced ovarian production of progesterone, but not of 17 beta-estradiol. The similarity of these results to those for tioconazole administered from days 15 p.i. or on days 18 and 19 p.i. suggests that tioconazole affects parturition in rats, at least in part, via LH.

Animals↗
PubMed1976

Parturition in the goat: plasma concentrations of prostaglandin F and steroid hormones and uterine activity during late pregnancy and parturition.

Changes in plasma concentrations of hormones and uterine activity associated with spontaneous parturition in the goat were examined. No change in oestradiol-17beta concentration was detected during the experimental period, but oestradiol-17alpha consistently increased in concentration 3-4 days before parturition. This was followed by an increase in prostaglandin F two days later, while a pre-partum decline in progesterone concentration occurred 18-20 h after the significant increase in prostaglandin F. The onset of uterine contractions coincided with a significant decline in progesterone concentration and a period of continually rising prostaglandin F and oestradiol-17alpha concentrations. Uterine activity expressed in Montevideo units did not change until 10-8 h before foetal expulsion. These results support the hypothesis that in the goat the elevated prepartum concentration of prostaglandin F brings about luteolysis and a subsequent decline in progesterone concentration.

Animals↗
PubMed1991

Hamster airway at parturition: ultrastructure of the full-term fetal trachea and effects of parturition.

Limited studies have described the ultrastructure of trachea of late fetal and neonatal hamsters but the effects of parturition and the onset of breathing on structure have not been discussed. This study describes morphological features of ante- and post-partum tracheal mucosa and submucosa and contrasts these features in fetal and neonatal hamster siblings. Significant differences between these siblings are noted in tracheal cells interfacing the lumen. Such cells of the fetal animals usually possessed cytoplasm of medium electron density with cisternal rough endoplasmic reticulum (RER). Surface membranes of these cells possessed numerous microvilli. In contrast, corresponding cells of post-natal animals often had lucent cytoplasm with mostly tubular or vesicular RER. Surface membranes of these cells possessed microplicae (microridges). This study also considers characteristics of fetal and neonatal tracheal development including: lomasome-like structures in secretory cells; dichotomous forms of oligocilia in mucosal and submucosal cells; intramembranous particles of hemidesmosomes; particles and mitochondria associated with desmosomes; and affiliations of ciliary basal bodies with the cytoskeleton, cell membrane, and with endoplasmic reticulum.

Animals↗
PubMed1981

Plasma norepinephrine, epinephrine, and dopamine concentrations in maternal and fetal sheep during spontaneous parturition and in premature sheep during cortisol-induced parturition.

The plasma catecholamine response to parturition was studied in two groups of chronically catheterized fetal sheep. Group I consisted of full term pregnancies with a mean gestation of 147 days at delivery. Group II was comprised of fetal sheep infused with cortisol to induce premature delivery at a mean gestational age of 135 days. Plasma catecholamine concentrations were measured in group I mothers and fetuses and group II fetuses by radioenzymatic assay using 50 microliter samples. Uterine contractions began 4--14 h before delivery in both groups. Significant increases in fetal plasma norepinephrine (NE) concentrations occurred within 3 h of delivery in both groups. Group I plasma epinephrine (E) and group I and II plasma dopamine levels were significantly increased within 1 h of delivery. Only plasma E levels differed in group I and II fetuses; there was no significant rise in plasma E concentrations in cortisol-infused (group II) fetuses. Maternal plasma NE and E concentrations were increased 2--3 h before delivery in group I animals. Maternal plasma dopamine concentrations were only elevated 30 min before delivery when plasma NE and E levels were highest.

Animals↗
PubMed1986

[A basic study on the initiation of human parturition--contribution of amniotic fluid and fetus to the initiation of human parturition].

In order to clarify the mechanism of initiation of human parturition, the relationship of amniotic fluid and fetus to prostaglandin synthesis was investigated. Phosphatidylinositol (PI) in amniotic fluid and phospholipase C (PLase C) activity in amniotic fluid, amnion tissue and neonatal urine were measured. The results are as follows. PI in amniotic fluid began to increase from around 30 to 36 or 37 weeks of gestation, and then gradually decreased toward term. PLase C activity in amniotic fluid was demonstrated. The activity was low before 30 weeks of gestation, but gradually increased toward term. PLase C activity in 105,000 X g supernate of amnion tissue homogenate was 43 fold higher than that in amniotic fluid. High PLase C activity was demonstrated in neonatal urine, which was 58 fold higher than that in amniotic fluid. The molecular weight of PLase C from neonatal urine was estimated to be 33,000 daltons. PLase C activity in neonatal urine has enough activity to produce arachidonic acid in amniotic fluid. It was concluded that the fetus relates to the onset of labor by producing arachidonic acid in amniotic fluid as a result of the reaction between PI from the lung and PLase C from the urine.

Amnion↗
PubMed1996

Oxytocin released within the supraoptic nucleus of the rat brain by positive feedback action is involved in parturition-related events.

Oxytocin is released within the supraoptic nucleus during parturition and suckling. During suckling, such release is important in positive feedback stimulation of oxytocin neurons. We have investigated whether oxytocin released within this hypothalamic nucleus during parturition (1) acts on local receptors to further amplify its own release in a positive feedback manner and (2) is critically involved in the regulation of the delivery process. To examine the effect of the oxytocin antagonist on oxytocin release within the supraoptic nucleus, microdialysates were sampled before and during parturition and either vehicle or the antagonist was infused adjacent to the microdialysis probe directly into the supraoptic nucleus after delivery of the second pup. Intranuclear infusion of an oxytocin receptor antagonist (des-Gly-NH2d(CH2)5[Tyr(Me)2Thr4]OVT; 50 ng/0.5 microliters) significantly (P < 0.01) diminished the parturition-related rise in oxytocin release within the supraoptic nucleus and reduced the number of pups delivered during the first and second 30-min dialysis period compared to vehicle-treated controls. Bilateral infusion of the oxytocin receptor antagonist into the supraoptic nucleus after delivery of the second pup significantly slowed parturition (P < 0.05), although the parturition-related rise in plasma oxytocin concentration was unchanged. In addition, the onset of suckling was significantly affected by the antagonist as indicated by fewer liver pups and fewer surviving pups with milk in their stomachs 24 hours after parturition (P < 0.05). To seek other, periventricular sites of oxytocin action during parturition, oxytocin or the oxytocin antagonist was infused into the lateral cerebral ventricle from the birth of pup 2. Via this route, oxytocin speeded up parturition, but the antagonist was ineffective; thus it appears that periventricular oxytocin-sensitive sites are not normally active in promoting parturition, and can do so. The findings indicate a receptor-mediated positive feedback action of oxytocin on its own release within the supraoptic nucleus during parturition, which seems to be involved in the progress of parturition without significantly affecting circulation oxytocin levels. Oxytocin released within the supraoptic nucleus might be important for the coordinated activation of oxytocin neurons and for the synergistic central and peripheral oxytocin effects involved in the regulation of parturition-related events necessary for the survival of the newborn, including the onset of lactation.

Animals↗
PubMed2002

Hormonal measurements in late pregnancy and parturition in dairy cows--possible tools to monitor foetal well being.

Three dairy heifers (A, B and C) were induced to parturition with two prostaglandin (PG) F(2alpha) injections on day 268 and 269 of pregnancy. Signs of approaching parturition were carefully observed. The following parameters were registered: degrees of calving difficulty, date and time of parturition, calf's birth weight and calf's sex. Body temperature was measured and blood samples were taken every 3 h 3 days before the first PGF(2alpha) injection until 3 days after parturition. The plasma concentrations of the PGF(2alpha) metabolite, progesterone, cortisol, oestrone sulphate and pregnancy associated glycoproteins (PAGs) were analysed. Heifers A, B and C delivered 48, 51 and 57 h after the first PGF(2alpha) injection, respectively. Heifer A delivered without any signs of calving difficulty, whereas, the parturition was considered to be slight and moderate difficulty occurred in the delivery of heifers B and C, respectively. The calf of heifer C, without any abnormal gross-evidences, was stillborn. All animals had retained foetal membranes. A slight increase of the PGF(2alpha) metabolite at the time of parturition was found only in heifer C, whereas the levels dramatically increased in all animals 15-24 h after parturition. At the same time, progesterone levels decreased within 3 h after the first PGF(2alpha) injection (P < 0.05) and reached 0.8, 2.7 and 12.4 nmol/l at the time of parturition in heifers A, B and C, respectively. High release of cortisol at the time of parturition was seen in heifer C. Rising levels of oestrone sulphate around the time of parturition were recorded in all heifers, whereas, increasing levels of PAGs were recorded only in heifer A. In conclusion, the patterns of the PGF(2alpha) metabolite, cortisol, progesterone and PAGs were changed in the cases of calving difficulty and stillbirth after PGF(2alpha)-induction of parturition. However, the relationship between oestrone sulphate and PAGs and the status of foetal well being prior to parturition require further elucidation.

Animals↗