Endocrine changes during pregnancy, parturition and the early post-partum period in the llama (Lama glama)

Mean (+/- s.d.) pregnancy length for the 14 llamas in this study was 350 +/- 4.5 days. Plasma progesterone concentrations increased by 5 days after mating and remained elevated (greater than 2.0 ng/ml) throughout most of pregnancy. At about 2 weeks before parturition, plasma progesterone concentrations began to decline, dropped markedly during the final 24 h before parturition, and returned to basal concentrations (less than 0.5 ng/ml) by the day of parturition. The combined oestrone + oestradiol-17 beta and oestradiol-17 beta concentrations varied between 6 and 274 pg/ml and 4 and 114 pg/ml, respectively, during the first 9 months of pregnancy. Concentrations increased between 9 months after mating and the end of pregnancy with peak mean concentrations of 827 +/- 58 (s.e.m.) pg oestrone + oestradiol-17 beta/ml (range: 64-1658) and 196 +/- 10 pg oestradiol-17 beta/ml (31-294) during the last week of pregnancy. Concentrations then declined to 87 +/- 14 pg oestrone + oestradiol-17 beta/ml (7-488) and 25 +/- 5 pg oestradiol-17 beta/ml (2.5-142) during the first week post partum. Plasma cortisol concentrations varied between 2.6 and 51.9 ng/ml (14.0 +/- 0.5) from mating until 2 weeks before parturition when the concentrations began to decline. Only a slight increase in plasma cortisol concentrations was observed in association with parturition. Plasma triiodothyronine concentrations varied between 0.5 and 4.5 ng/ml (1.9 +/- 0.1) throughout pregnancy and the periparturient period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pregnancy-associated glycoprotein concentrations during pregnancy and the postpartum period in Azawak Zebu cattle

Specific RIA systems were developed and used to measure pregnancy-associated glycoprotein (PAG) concentrations during gestation and the postpartum period in Azawak Zebu cows. Twelve females were palpated per rectum and diagnosed as pregnant. Blood samples were taken at 5-10-day intervals from approximately Week 8 of gestation until Week 10 postpartum (pp). One Zebu cow (Z15) initially diagnosed as pregnant showed PAG concentrations lower than the assay sensitivity (<0.20 ng/ml) and did not calve. Another cow (ZSand) showed abnormally high PAG concentrations during gestation and was excluded from the general PAG profile. The 10 other Zebu cows exhibited a very similar PAG profile. In these animals, concentrations increased progressively from Week 8 to 35 of gestation (from 6.0+/-4.2 to 196.0+/-34.8 ng/ml), remaining relatively constant until Week 39 (210.8+/-74.8 ng/ml), when they increased sharply to reach their highest level (1095.6+/-607.2 ng/ml) at around parturition. After delivery, PAG concentrations declined significantly (P<0.05) until Week 2 postpartum (348.4+/-85.6 ng/ml) and slowly until Week 10 postpartum. Our results revealed that the PAG pattern in Zebu cattle was similar to those of taurine breeds during the first two trimesters of pregnancy, but differed in the peripartum period.     

Mesotocin receptors during pregnancy,parturition and lactation in the tammar wallaby

Mestocin receptor concentrations in membrane preparations from reproductive tissues of the tammar Macropus eugenii throughout gestation and lactation were assessed using [³H]-oxytocin as the ligand. There was a single binding site which bound both mesotocin and oxytocin with high and similar affinities. Mesotocin receptor concentrations in the myometrium were low (708±199 fmol mg⁻¹ protein) in early and middle gestation but increased significantly on day 23 of pregnancy of the 26-day gestation period to 1921±552 fmol mg⁻¹ protein. Myometrial receptors reached a peak of 2483±575 fmol mg⁻¹ protein on days 25 and 26 of gestation, but returned to basal levels about an hour after birth. Receptor concentrations in the contralateral non-gravid uterus were much lower (605±75 fmol mg⁻¹) and did not significantly increase throughout the period of gestation but dropped one day before birth. Mesotocin receptors were undetectable in the endometrium, the yolk sac placenta and the lateral, median and anterior vagina of all animals tested. In the lactating mammary gland after birth mesotocin receptors were initially high (588±38 fmol mg⁻¹) but decreased after 200 days and by late lactation were 224±55 fmol mg⁻¹ protein on day 240, close to the time of weaning. Mesotocin receptors in the ipsilateral non-lactating gland were also high in early lactation (430±153 fmol mg⁻¹) and declined in late lactation (62±20 fmol mg⁻¹). The changing concentrations of mesotocin receptors in pregnancy and lactation demonstrate that they are specifically regulated in tammar reproductive tissues. The increase in mesotocin receptors in gravid, but not in the non-gravid myometrium three days before birth may make the uterus responsive to the surge of mesotocin at birth. Since this rise is unilateral and only occurs in the gravid myometrium it must be due to local effects from the ipsilateral ovary or the feto-placental unit. Likewise, the down-regulation of mesotocin receptors in the contralateral, non-gravid myometrium may be due to its proximity to the developing follicle. The changing concentrations in the lactating and the adjacent, non-lactating mammary gland also reflect a differential regulation of mesotocin receptors, probably mediated via the sucking stimulus. Thus, local influences appear to be of primary importance in the regulation of mesotocin receptors during reproduction in this marsupial.     

Changes in concentrations of follistatin in maternal plasma and foetal fluids during pregnancy and parturition in sheep

Studies have shown that follistatin may be involved in the regulation of ovarian development, pregnancy and parturition. The aim of the present study was to measure follistatin levels in maternal plasma and foetal fluids during pregnancy and parturition in sheep. Using a previously described follistatin radioimmunoassay, we found that follistatin in foetal plasma and allantoic fluid was higher in the female than in the male at days 50-75 of gestation. Follistatin concentrations in maternal plasma declined from -9 to -3h before the completion of lamb delivery, and increased from 21 to 39 h after parturition. These results suggest that follistatin may play a role in femaleness development, and that follistatin may be involved in the mechanism of normal parturition and in regulation of the tissue repair after parturition.     

Regulation of elastolytic proteases in the mouse vagina during pregnancy, parturition, and puerperium

Recent evidence indicates that failure of elastic fiber assembly and synthesis is involved in the pathophysiology of pelvic organ prolapse in mice. It has been long been hypothesized that parturition-induced activation of proteases in the vaginal wall and its supportive tissues may contribute to pelvic organ prolapse in women. In this investigation, we determined the expression of matrix metalloproteases with elastase activity (matrix metalloproteinase [MMP] 2, MMP9, and MMP12) and their inhibitors in the vaginal wall of nonpregnant, pregnant, and postpartum mice. Data obtained using mRNA levels and enzyme activity measurements indicate that MMP2, MMP9, and 21- to 24-kDa caseinolytic serine proteases are regulated in vaginal tissues from pregnant and postpartum mice. Although suppressed during pregnancy and the early postpartum time period, MMP2 and MMP9 enzyme activities are increased after 48 h, a time when mRNA levels of protease inhibitors (tissue inhibitor of MMP2 [Timp2], cystatin C [Cst3], and alpha-1 antitrypsin [Serpina1]) are decreased. We conclude that recovery of the vaginal wall from pregnancy and parturition requires increased elastic fiber assembly and synthesis to counteract the marked increase in elastolytic activity of the postpartum vagina.     

Progesterone supplementation during the early fetal period reduces pregnancy loss in high-yielding dairy cattle

It was hypothesized that sub-optimal progesterone concentrations during the late embryo and early fetal period may act to compromise conceptus development in dairy cattle. The aim of the present study was to test this hypothesis by supplementing pregnant cows with exogenous progesterone following pregnancy diagnosis. The study population consisted of 1098 pregnant lactating cows. Pregnancy was diagnosed by transrectal ultrasonography between 36 and 42 days after insemination. Animals found to be pregnant were randomly assigned to the Control (untreated cows, n = 549) or Treatment (n = 549) groups. Cows in group Treatment were fitted at pregnancy diagnosis with a progesterone releasing intravaginal device (PRID) containing 1.55 g of progesterone, for 28 days. Cows were then subjected to a further diagnosis by palpation per rectum on Day 90 of gestation. Pregnancy loss was registered in 95 (8.7%) cows on Day 90 of pregnancy: 66 (12%) in group Control and 29 (5.3%) in group Treatment. Logistic regression analysis indicated that there were no significant effects of herd, bull, milk production, service number, days in milk at pregnancy and lactation number. Based on the odds ratio, treated cows were 2.4 (1/0.41) times less likely to miscarry, whereas the risk of pregnancy loss was 1.6 times higher in cows that became pregnant during the warm period in comparison to the cool period. These results support the hypothesis that sub-optimal progesterone concentrations in high producer dairy cows may compromise conceptus development. Under these conditions, intra-vaginal progesterone supplementation has the potential to reduce the incidence of pregnancy loss during the early fetal period.     

Idiopathic thrombocytopenic purpura in pregnancy and neonatal period

In pregnancy and neonatal period both mother and child are endangered by bleeding complications due to maternal idiopathic thrombocytopenic purpura. Obstetrical and perinatal management therefore must aim at increasing maternal and fetal platelet count. In our paper six patients in nine pregnancies are reported. Two of them (five pregnancies) were treated with corticosteroids, four of the patients were successfully treated with i.v. immunoglobulins (IgG). Longterm steroid application and splenectomy during pregnancy may be hazardous for mother and fetus. IgG i.v. administration in contrast offers a new and safe way to control maternal and fetal platelet counts during pregnancy, delivery and the neonatal period.     

Total and free plasma concentrations of progesterone, cortisol and oestradiol-17 beta during pregnancy, parturition and early lactation in sows

The total (bound plus free) concentrations of progesterone, 20 alpha-dihydroprogesterone, oestradiol-17 beta and cortisol were determined in the plasma of sows at three stages during pregnancy and more intensively from 5 days pre-partum to 5 days post-partum. The free fractions of progesterone, oestradiol-17 beta and cortisol were measured in the same samples by a rate dialysis method. Up to day 110 of gestation, the amounts of free hormone in plasma did not fluctuate independently of their total concentrations. During farrowing, the total and free concentrations of progesterone and cortisol varied independently of each other, whereas total and free oestradiol-17 beta declined simultaneously. The initiation of parturition was associated with a decrease in circulating total progesterone, and was accentuated by a decrease in the free fraction (P less than 0.005) so that its active free concentration was only 20% of its day 1 pre-partum value. Total and free cortisol concentrations rose rapidly during labour so that at 12-18 h after birth of the first piglet 30% of that cortisol in maternal plasma was free hormone.     

Plasma oxytocin concentrations during late pregnancy and parturition in the dog

While oxytocin is widely used in the treatment of dystocia in dogs, there is little information about its secretion before and during normal unassisted whelping. We therefore measured plasma oxytocin concentrations during late pregnancy and the expulsive stage of parturition. Blood samples were collected from eight dogs at 3-min intervals during a 42-min period between the 2nd and 14th day before whelping and during parturition after the birth of 1-3 pups. The litters consisted of 5-15 pups and the progression of the expulsive stage was linear and nearly parallel in the eight bitches. The overall mean (+/-S.D.) plasma oxytocin concentration during late pregnancy was 3.6+/-2.1pg/ml. Mean values in individual dogs ranged from 1.2 to 7.4 pg/ml, but the intra-animal variation was rather small. During the expulsive stage the overall mean (+/-S.D.) plasma oxytocin concentration was 12.9+/-13.9 pg/ml, with mean values in individual dogs ranging from 3.5 to 46 pg/ml. The mean area under the oxytocin curve for parturient dogs was significantly higher (P<0.05) than for pregnant dogs. During the expulsive stage, the peak plasma oxytocin level in individual dogs ranged between 10 and 117 pg/ml. In six of the eight dogs a pup was born during blood collection and in five of these animals the plasma oxytocin concentration increased temporarily during periods of abdominal straining and expulsion. However, straining efforts and expulsion were not consistently associated with a rise in the circulating oxytocin level. It is concluded that in the dog plasma oxytocin levels are higher and more variable during the expulsive stage of parturition than during late pregnancy. Interrelationships between the secretion pattern of oxytocin, the level of uterine contractility, and the progress of fetal expulsion in dogs need further exploration.     

Secretion of unconjugated estrone during pregnancy and around parturition in goats

The secretion of unconjugated estrone and its production site in pregnant goats were investigated in vivo. The mean estrone concentration (n = 15) in the peripheral plasma increased gradually, being 83 pg/ml on Day 40 and 483 pg/ml on Day 140 after mating. The estrone concentration increased rapidly after Day 2 before partum, reaching a peak at parturition (2370 pg/ml), and falling to 171 pg/ml at Day 1 post partum. The concentrations of estrone from the umbilical vein and umbilical artery did not differ from that found in the maternal jugular vein, suggesting that the fetus does not take part in estrogen production. The estrone concentration from the uterine vein after the fetus was removed was higher than the concentrations found in the maternal jugular vein and umbilical artery. In the placental tissue, a high concentration of estrone (18157 pg per gram of wet tissue) was detected. These findings suggest that the main production site of unconjugated estrone is the placenta.