Water movements after an intraruminal water load in pregnant and lactating Sardi sheep

The effects of an intraruminal load of 3 litres of water on body water movements was compared in Sardi sheep during the last month of pregnancy, lactation and a non-pregnant, non-lactating control period. Before the water load, rumen fluid volume, estimated by polyethylene glycol was similar in pregnant, compared to control, animals and 27% higher in lactating sheep. After the water load, rumen volume returned to pre-hydration level in 1 h during pregnancy, after 3 h during lactation and in the control period. Rumen osmolality decreased by 40% and remained at this low level for 3 h after the water load in all physiological periods. When the water load was tritiated water (TOH), the rate of TOH transfer into plasma was faster during the last month of pregnancy than during the control period. Plasma osmolality and proteins decreased in response to the water load. No differences in these responses were observed between pregnancy, lactation and the control period. Water diuresis began in the first 30 min following the water load in pregnant ewes and in the second 30 min in lactating and control ewes. The diuresis was also more pronounced in pregnant, than in non-pregnant, states. These results indicate that water is more rapidly absorbed from the gastrointestinal tract in pregnant, rather than in non-pregnant, sheep. This may partly explain the increased water turnover seen during pregnancy.     

Changes in phospholipase A2 in myometrium of the guinea pig uterus during pregnancy.

Phospholipase A2 activity has been measured in membrane and cytosolic fractions from non-pregnant and pregnant guinea pig myometrium has been studied. Enzyme activity was measured with 1-stearoyl-2- [3H]arachidonoyl-phosphatidylcholine exhibiting Michaelis-Menton kinetics with Km of 83.8 +/- 21.6 and 53.2 +/- 14.1 for membrane and cytosolic enzymes respectively. Fractionation of the myometrium from non-pregnant guinea pigs suggested that 35% of the activity was membrane associated compared with 20% (P < 0.01) in tissue from pregnant animals. In the presence of 1 mM calcium total activity rose from 3.03 +/- 0.41 to 1737 +/- 368 nmol/h per uterus between non-pregnant and late pregnancy. Calcium activated the membrane enzyme, but the effect was greater late in pregnancy with almost a 6-fold increase in activity at 1 mM calcium compared with a doubling in membrane from non-pregnant guinea pigs. The K0.5 for calcium activation was about 150 microM. Immunoblotting with anti-human-110 KDa phospholipase A2 showed in guinea pig uterus a 34 KDa form of the enzyme that, consistent with changes in activity, showed a fifteen-fold increase in quantity between non-pregnant and late pregnancy. The data are consistent with dramatic increases in the capacity for arachidonic acid release and prostaglandin production in the guinea pig myometrium late in pregnancy.     

Acid phosphatase and leucine aminopeptidase activity in the uterine flushings of non-pregnant and pregnant gilts

The activities of uteroferrin, measured as acid phosphatase (AP), and an aminoacylpeptidase (AA) were measured in uterine flushings collected from gilts on Days 6, 8, 10, 12, 14, 15, 16 and 18 of the oestrous cycle and pregnancy (N = 37). Changes in AP (P less than 0.05) were associated with day for both specific and total AP in non-pregnant and pregnant gilts. For pregnant and non-pregnant gilts, AP activity was greatest between Days 14 and 16 and then decreased to Day 18. The AA specific activity increased (P less than 0.01) between Days 10 and 12 of the oestrous cycle and pregnancy, but neither effects of pregnancy nor day by pregnancy status interaction were detected. The AA total activity was greater for pregnant gilts (P less than 0.01). These data suggest an inhibitory effect of oestrogens of blastocyst origin on synthesis and/or secretion of uteroferrin, but not AA.     

Fatty acid metabolism of the perfused caudate lobe from livers of fed and fasted non-pregnant and fasted late pregnant ewes

1. Fatty acid metabolism has been compared in perfused liver lobes from fed and fasted non-pregnant sheep and fasted pregnant sheep to provide further information on the control of ketogenesis in this species. 2. Ketogenesis from exogenous palmitate was greatest in lobes from fasted pregnant sheep and least in lobes from fed non-pregnant sheep, whereas rates of ketogenesis from exogenous octanoate (0.4 mM) were similar in lobes from sheep in all three states. 3. High rates of ketogenesis from endogenous fatty acids occurred in perfused lobes from fasted pregnant sheep, apparently owing to enhanced lipolysis. 4. Activities of glycerol-3-phosphate acyltransferase, carnitine palmitoyl transferase (CPT) and other enzymes involved in ketone production did not change with physiological state; sheep differ markedly from rats in this respect. 5. The results suggest that the primary point of control of ketogenesis within the liver of sheep is at the level of CPT; the lack of change in maximum CPT activity suggests that control by modulators of this enzyme activity is even more important in sheep than in rats.     

Responses of the uterine circulation to sympathetic nerve stimulation

Pregnant and non-pregnant sheep uteri were perfused in situ with arterial blood at a constant flow rate. Unilateral stimulation (1-2 ma, u ms pulse) of the distal end of the severed sympathetic chain (L3-L4) at frequencies between 5 and 25 Hz produced a graded increase in uterine artery pressure in both horns. At 25 Hz, pressure in the horn ipsilateral to the stimulated sympathetic chain increased by 28 +/ 2% in four pregnant animals and 32 +/ 5% in six non-pregnant ewes. The response of the contralateral horn was significantly smaller than that of the ipsilateral horn (P less than or equal to 0.05). The response was alpha-mediated since it was abolished by local injection of dibenzyline into the middle uterine artery. The responses of the pregnant and non-pregnant animals were similar, indicating that pregnancy did not alter the alpha-adrenergic responses of the uterine vasculature.     

Increase in concentrations of prostaglandin endoperoxide synthase and prostacyclin synthase in human myometrium in late pregnancy

Concentrations of prostaglandin endoperoxide synthase (i.e. cyclooxygenase; PGH synthase) and prostacyclin synthase (PGI synthase) were quantified with specific radioimmunometric assays in human myometrium during the last trimester of pregnancy (n = 23) and in non-pregnant controls (n = 8). Pregnant myometrium contained 3 times more PGH synthase per mg microsomal protein than non-pregnant myometrium (p less than 0.01) but there was no increase with increasing gestational age in the third trimester nor with the onset of labor. In pregnancy, as compared to the non-pregnant state, there was no significant change in the PGI synthase content of myometrial microsomes, but significantly more PGI synthase was recovered in other subcellular fractions (p less than 0.01). This suggests that pregnancy affects preferential changes in the subcellular distribution of PGI synthase in myometrial cells. Relative to its PGI synthase content pregnant myometrium contained twice as much PGH synthase as non-pregnant myometrium (p less than 0.01). This may offer further evidence that PGH synthase rather than PGI synthase itself is the rate limiting factor in myometrial PGI2 production. On the other hand, the much larger increase in PGH synthase than in PGI synthase in pregnant as compared to non-pregnant myometrium, may serve to promote preferential synthesis of prostaglandins that are potent myometrial stimulants and of critical importance in human parturition.     

Distribution of Methylene Blue after Injection into the Epidural Space of Anaesthetized Pregnant and Non-Pregnant Sheep

The aim of the study was to determine the distribution of different volumes of methylene blue solution injected into the epidural space in anaesthetized pregnant and non-pregnant sheep, to evaluate its cranial distribution and to compare between them. Fifteen pregnant and fifteen non-pregnant sheep were included in the study. Sheep were anaesthetized and received 0.05, 0.1, or 0.2 mL/kg of a lumbosacral epidural solution containing 0.12% methylene blue in 0.9% saline. Thirty minutes after the epidural injection, the ewes were euthanized. The extension of the dye within the epidural space was measured, and the correlation between the volume of the dye injected and the number of stained vertebrae was evaluated. The cranial migration of the dye between pregnant and non-pregnant sheep was also compared. The results show that the volume of methylene blue injected epidurally into pregnant and non-pregnant sheep correlated directly with its cephalic distribution into the epidural space; and a volume of 0.1 mL/kg or 0.2 mL/kg stained up to the first lumbar segment in pregnant and non-pregnant sheep, respectively. Also, the results suggest that the volume of drugs administered into the epidural space of pregnant sheep should be half the volume that would be used in non-pregnant sheep.     

Increase in concentrations of prostaglandin endoperoxide synthase and prostacyclin synthase in human myometrium in late pregnancy

Concentrations of prostaglandin endoperoxide synthase (i.e. cyclooxygenase; PGH synthase) and prostacyclin synthase (PGI synthase) were quantified with specific radioimmunometric assays inhuman myometrium during the last trimester of pregnancy (n=23) and in non-pregnant controls (n=8). Pregnant myometrium contained 3 times more PGH synthase per mg microsomal protein than non-pregnant myometrium (p < 0.01) but there was no increase with increasing gestational age in the third trimester nor with the onset of labor. In pregnancy, as compared to the non-pregnant state, there was no significant change in the PGI synthase content of myometrial microsomes, but significantly more PGI synthase was recovered in other subcellular fractions (p < 0.01). This suggests that pregnancy affects preferential changes in the subcellular distribution of PGI synthase in myometrial cells.Relative to its PGI synthase content pregnant myometrium contained twice as much PGH synthase as non-pregnant myometrium (p < 0.01). This may offer further evidence that PGH synthase rather than PGI synthase itself is the rate limiting factor in myometrial PGI₂ production. On the other hand, the much larger increase in PGH synthase than in PGI synthase in pregnant as compared to non-pregnant myometrium, may serve to promote preferential synthesis of prostaglandins that are potent myometrial stimulants and of critical importance in human parturition.     

Barium responsiveness of the rat aorta and femoral artery during pregnancy

The barium responses of isolated aortic strips and femoral arteries from non-pregnant and pregnant rats were investigated. Barium caused concentration-related increases in tension of vessels from both pregnant and non-pregnant rats. The concentration-response curves of femoral arteries from non-pregnant and 3 week pregnant rats were not different; however contractility and slopes of concentration-response lines for thracic aortas from 1, 2 and 3 week pregnant rats were significantly less than those of aortas from non-pregnant rats. In addition, barium caused rhythmic contractions to develop in both femoral arteries and aortas of 3 week pregnant rats more frequently than vessels from non-pregnant rats. Rhythmic contractions did not develop in aortas from 3 week pregnant rats rats in calcium-free Krebs. Since the effects of barium on the electrical and mechanical activity of various muscles have been postulated to be similar to and/or dependent on calcium, these results may indicate that changes in calcium sensitivity of vascular smooth muscle occur during pregnancy. Such changes may contribute to the blood flow redistribution and other cardiovascular adaptations of pregnancy.     

Some observations on the behaviour of hypothalamic enzymes during the time of blastocyst implantation in the rabbit

1. Hypothalami from pregnant and non-pregnant rabbits were homogenized in sucrose and separated into fractions by differential and density-gradient centrifugation. 2. The fractions were examined for enzymes capable of inactivating oxytocin. 3. Enzyme activity was detected in the supernatant and one particulate fraction of both pregnant and non-pregnant animals. 4. The specific activity of the enzymes increased during early pregnancy, and coincided with the time of blastocyst spacing and implantation in the uterus.     

Assessment of plasma profile of pregnancy-associated glycoprotein (PAG) in sheep with a heterologous (anti-caPAG55+59) RIA and its potential for diagnosing pregnancy

The purpose of the present investigation was to generate pregnancy associated glycoprotein (PAG)-profiles throughout pregnancy in a heterogenous sample of sheep using a radioimmunoassay with a heterologous antibody (anti-caPAG(55+59), #708) and utilize them for the purpose of pregnancy detection. From 2 weeks after the introduction of males into the breeding herd until 4 weeks after parturition, weekly blood samples were collected from 66 pregnant and 25 non-pregnant ewes of various breeds. Between 3 and 5 weeks after conception, plasma PAG levels increased, remained almost stable until week 17, then continued to increase, culminating in a drastic surge during the last 2 weeks of pregnancy. By 4 weeks of gestation, the plasma PAG level exceeded the level typical for non-pregnant ewes by five standard deviations, permitting a reliable pregnancy diagnosis. Plasma PAG levels were higher in twin-bearing ewes than in ewes carrying a single lamb, differences getting more evident as pregnancy proceeded. Neither breed and parity of the mother nor sex and weight of lambs borne exerted a significant effect. The heterologous assay system utilizing a caprine antibody proved to deliver results that are more consistent and less depending on various variables than those used in other studies. It may be concluded that, at the present state of development, the assay provides a reliable means of diagnosing pregnancy in sheep from the 4th week after they have been bred onward.     

Effect of chorionic gonadotropin, triamcinolone, progesterone and estrogen on enzymes of placenta and liver in rats

The activity of several enzymes of regulatory importance for the pathways of glycolysis, gluconeogenesis and lipogenesis was investigated in the placenta and liver of pregnant rats and in the liver of non-pregnant female rats. The rats received daily hormonal treatments on Days 15 to 17 of pregnancy and enzyme activities were measured on Day 18. Chorionic gonadotropin induced minor changes in enzyme activity, apart from a decrease in the activity of hepatic enzymes of lipogenesis in non-pregnant rats. Triamcinolone induced a marked increase in enzymes of gluconeogenesis and a decrease in the activity of pyruvate k kinase in the liver of pregnant and non-pregnant rats; in contrast, inverse changes in activity, these enzymes were observed in the placenta. This response in the placenta was considered to arise not from direct hormone effect, but from the accompanying hyperglycemia and hyperinsulinemia. Triamcinolone also increased the activity of hepatic acetyl-CoA carboxylase in pregnant and non-pregnant rats, whereas it reduced the activity of this enzyme in the placent. Estrogen produced changes similar to those of triamcinolone in the liver and placenta, except that it depressed the activity of acetyl-CoA carboxylase in both tissues. Progesterone had little effect on placental and hepatic enzymes. In general, the changes induced by these hormones in the placenta affected fewer enzymes than in the liver, were less extensive in magnitude and not necessarily in the same direction as in the liver. This indicates that the regulatory placental enzymes are subject to specific control mechanisms not necessarily influenced by direct hormone action.     

Differences of microvascular endothelium in the bovine corpus luterum of pregnancy and the corpus luteum of the estrous cycle

Summary— The purpose of the present study was to investigate potential modulations of endothelial cells of the bovine corpus luteum (CL) during pregnancy. Luteal endothelia of pregnant and non-pregnant cows were isolated and purity of cultures was verified by flow cytometric quantification of three independent endothelial markers (von Willebrand factor, angiotensin converting enzyme, Bandeiraea simplicifolia agglutinin I ligands). Different cellular parameters including light and electron microscopical investigation of morphology and growth characteristics as well as quantification of cellular lectin binding sites were compared. Extensive heterogeneity between luteal endothelial cells in pregnant and non-pregnant animals could be demonstrated, reflected in functional attributes like angiogenic activity, ultrastructural characteristics and the quantitative expression of cellular carbohydrates. Two different morphological types of cells (‘cobblestone growth pattern’ and ‘arcuate growth pattern’) were isolated from the CL of pregnancy as well as from the cyclic CL. Spontaneous angiogenic activities, including cellular migration in band-like structures and formation of ring-like structures, were observed in endothelial cells isolated from the CL of pregnant cows exclusively. This strongly suggests that microvascular luteal endothelium of pregnant animals, in contrast to the one of non-pregnant animals, is able to produce quantitatively and/or qualitatively specific angiogenesis factor(s). Heterogeneity between luteal endothelial cells in the pregnant and non-pregnant animal could also be demonstrated by quantification of lectin (Bandeiraea simplicifolia agglutinin I, concanavalin A, Dolichos biflorus agglutinin, Ulex europaeus agglutinin I, wheat germ agglutinin) binding sites: quantitative expression of specific endothelial cell surface carbohydrates could be correlated to be status of pregnancy, thus emphasizing the actual need of quantification of lectin binding.     

Effects of early pregnancy on regional adipose tissue metabolism

Adipose tissue metabolism was studied in needle biopsies from femoral and abdominal subcutaneous depots, in 12 healthy young women, during early (9-11 weeks) pregnancy, and 6 weeks after a legal abortion. Both during pregnant and non-pregnant conditions, a higher lipoprotein lipase (LPL) activity was seen in the femoral compared to the abdominal region, but the LPL activity was not influenced by early pregnancy. Rates of fatty acid esterification and acylglyceride synthesis were not different between regions, nor affected by pregnancy. The stimulatory effect of norepinephrine (10(-7) M) on lipolysis was significantly greater in the abdominal than in the femoral region in both the pregnant and non-pregnant condition. This difference was apparently due to higher alpha-adrenergic activity in the femoral region. Pregnancy per se had no effect on lipolytic response to norepinephrine. These findings indicate that lipid accumulation is favoured in the femoral region in young women both during pregnant and non-pregnant conditions.     

High intensity exercise during pregnancy of rats. Effects on mother and offspring

We see in this study the effect of high intensity exercise (90% VO₂ max) in pregnant rats and their offspring depending on the length of pregnancy. The findings were compared with those obtained for sedentary pregnant rats and non-pregnant rats for similar exercise. This allowed for analysing the isolated effects of exercise (against the sedentary non-pregnant rat control group), of pregnancy and of the interaction between the two factors. For checking the effect of the length of pregnancy, each group of rats was subdivided into those with pregnancy terminated or sacrificed on the seventh, fourteenth or twentieth day of the experiment. VO₂ max, post-exertion blood lactic acid level, body weight gain, food intake, feed efficiency, glucose, triglyceride, total cholesterol, total protein and albumin plasmatic concentrations in adult rats, and weight and number of offspring of pregnant rats were determined. Pregnancy increased weight gain and feed efficiency from the first week of the study, accompanied by a greater food intake (from the twelfth day). In the group of pregnant rats subjected to exercise, there was a reduction in weight gain percentage and feed efficiency in the first and third weeks, staying the same in the second week. A greater food intake during the period accompanied this recovery in the second week. In the group of non-pregnant rats subjected to exercise, food intake did not vary. As the weight gain percentage was less in relation to the non-pregnant control group, feed efficiency decreased. Pregnancy induced a drop in blood sugar level starting in the second week, and the exercise performed during pregnancy did not change this behavior. Pregnancy produced, however, an increase in plasmatic concentration of triglycerides and total cholesterol during the third week of pregnancy. Exercise performed by pregnant rats also did not change this behavior, but the increase observed in the third week was less. Exercise performed by non-pregnant rats did not change the blood sugar level and plasmatic concentration of triglycerides and total cholesterol during the entire experiment. Plasmatic concentration of total proteins and albumin showed a drop in the third week of pregnancy, probably due to high fetal use of proteins in this stage. Exercise performed by the pregnant group caused a lower protein drop in the third week, and in the non-pregnant group, determined an increase in plasmatic protein concentrations. The weight of the offspring of mother rats exercised until the end of the second and third weeks of pregnancy was found to be reduced in relation to the sedentary pregnant group. The group exercised until the third week showed a reduction in the number of offspring, indicating a possible fetal reabsorption. These findings confirmed that high intensity exercise can produce deleterious effects on the mother and fetus, especially when applied up to the last stage of pregnancy.     

Lower prevalence of chromosome aberrations and SCEs in self-poisoned pregnant women

A cytogenetic investigation was conducted in 18 self-poisoned pregnant and 16 self-poisoned non-pregnant women and in 31 pregnant and non-pregnant controls. Blood samples for analysis of chromosomal aberrations and SCEs were collected from women who were at different early stages of pregnancy. The difference between self-poisoned women and controls was very highly significant in the case of chromatid-type and unstable chromosome-type aberrations and highly significant in the case of SCEs. Further, the frequency of chromatid aberrations in pregnant women relative to non-pregnant ones was significantly lower suggesting a possible protective effect of pregnancy.     

An immunochemical demonstration of a pregnancy-specific protein in the horse and its use in the serological detection of early pregnancy

Two-dimensional crossed immunoelectrophoresis of sera from pregnant and non-pregnant horses, using antisera developed against early pregnant mare serum, revealed the presence of two immunologically related proteins one of which appeared to be specific to the pregnant state. This pregnancy-specific protein had beta 2-electrophoretic mobility and was first detectable at Day 6 after successful mating with a stallion. The second protein had gamma 2-electrophoretic mobility and was present in sera from pregnant and non-pregnant horses. The proteins were termed beta 2-horse pregnancy protein and gamma 2-horse protein respectively. The latter appeared to be immunologically related to the former in that the precipitin lines of the 2 proteins showed continuity. Samples from 16 mares mated with a stallion were investigated for the beta 2-protein during the first 3 weeks after mating. Of the 11 successful matings, confirmed by ultrasonic scanning at 90 days or by a successful outcome, 10 mares showed the presence of the protein. In all of 14 non-pregnant sera taken from mares not recently mated, the protein was not detectable. The validity of detection of beta 2-protein as an indication of pregnancy was clinically significant at the 10% level. The presence of the protein in 2 out of the 5 recently mated mares that did not become pregnant may be indicative of a biochemical pregnancy that failed at a later stage of gestation.     

Prostaglandin production by the pregnant and non-pregnant rabbit uterus

We have studied the prostaglandin synthesis of the pregnant and non-pregnant rabbit uterus in a microsomal membrane preparation, and in an ex vivo perfused uterus preparation which retains agonist stimulated prostaglandin production. In both the microsomal and isolated perfused system, prostacyclin was the major arachidonic acid metabolite produced; PGE2 was also produced in substantial quantities while TxB2 and PGF2 alpha were not detectable. Moreover, oxytocin was a specific stimulus of PGE2 release. The steroid hormone milieu influenced the level of agonist stimulated prostaglandin release; in general, ovariectomized, estrogen treated animals were more responsive to agonist stimulation than those treated with estrogen followed by progesterone. The microsomal studies indicated that the pregnant animal had a greatly enhanced capacity to metabolize arachidonic acid when compared with the non-pregnant animal. However, this was not reflected in the ability of agonists to stimulate prostaglandin release in the ex vivo perfused preparation.     

Has cervical smooth muscle any physiological role in the human?

Strips of human cervical tissue were obtained by needle biopsy and contractile activity was registered isometrically in a tissue chamber perfused by Krebs-Ringer bicarbonate buffer. The most frequently encountered pattern of contractile activity was high frequency-short duration. Prostaglandin (PG)E2, PGI2 and 6-keto-PGF1 alpha had an inhibitory effect on the muscular activity. Cervical muscle from pregnant women was more sensitive to PGE2 than specimens from non-pregnant women. PGF2 alpha had no apparent effect on cervical contractility in non-pregnant and early pregnant patients. In late pregnancy, however, PGF2 alpha inhibited muscle contractions. The present results point to a physiological role of the cervical muscles for the control of cervical competence during pregnancy. The inhibitory effect of PGs on the muscle activity may promote cervical dilatation and retraction.     

Study of cystinaminopeptidase heterogeneity in animal sera by the isoelectric focusing method.

Study of the quantitative distribution of cystinaminopeptidase activity in the serum of pregnant and control animals (cow, sheep and rat) by the isoelectric focusing method showed heterogeneity of the cystinaminopeptidase activity of the animals' serum enzymatic system, which was well pronounced in the cow and rat and less pronounced in the sheep. The authors assume from their results that the principal difference between the pregnant and control animals is not the total increase in the level of activity of the enzyme in question, but the shift in its incidence, or the increase in activity at a given pH. It is possible that pregnancy, in man and animals, produces in the serum cystinaminopeptidase system (which is evidently heterogeneous even under normal, physiological conditions) given changes, i.e. the formation of new fractions with a different pI from the controls; other fractions disappear, or their activity diminishes.