The role of prostaglandins in obstetrical disorders

Vasomotor tone-associated factors and pregnancy outcomes of women who undergo in vitro fertilization

Vasomotor tone-associated factors play important roles in normal pregnancy, but their roles in the pregnancy outcome of women who undergo in vitro fertilization and embryo transfer (IVF-ET) remain unclear. A total of 82 infertile women who underwent successful IVF-ET were enrolled, including 18 pregnancy losses, 11 complications, and 53 normal deliveries. The serum NO and iNOS levels were significantly higher in the pregnancy loss group and significantly lower in the complication group than in the normal delivery group (p < 0.05). Significantly increased ET-1 and decreased PGI2 were found in both the pregnancy loss and complication groups compared with those in the normal delivery group (p < 0.05). NO, iNOS, and ET-1 are risk factors and PGI2 is a protective factor for pregnancy loss. ET-1 + PGI2 (AUC, 0.897; sensitivity, 90.6%; specificity, 83.3%) showed a relatively good predictive value for pregnancy loss following IVF-ET.

Can Endothelial Glycocalyx Be a Major Morphological Substrate in Pre-Eclampsia?

Today pre-eclampsia (PE) is considered as a disease of various theories; still all of them agree that endothelial dysfunction is the leading pathogenic factor. Endothelial dysfunction is a sequence of permanent immune activation, resulting in the change of both the phenotype and the functions of an endothelial cell and of the extracellular layer associated with the cell membrane—endothelial glycocalyx (eGC). Numerous studies demonstrate that eGC mediates and regulates the key functions of endothelial cells including regulation of vascular tone and thromboresistance; and these functions are disrupted during PE. Taking into account that eGC and its components undergo alterations under pathological conditions leading to endothelial activation, it is supposed that eGC plays a certain role in pathogenesis of PE. Envisaging the eGC damage as a key factor of PE, might be a new approach to prevention, treatment, and rehabilitation of patients with PE. This approach could include the development of drugs protecting eGC and promoting regeneration of this structure. Since the issue of PE is far from being solved, any effort in this direction might be valuable.

The role of α2-adrenergic receptors in hypertensive preeclampsia: A hypothesis

Preeclampsia, a major disorder of human pregnancy, manifests as persistent hypertension and proteinuria presenting after 20 weeks of pregnancy. Multiple systemic symptoms might be associated with preeclampsia including thrombocytopenia, liver impairment, pulmonary edema, and cerebral disturbances. However, vascular dysfunction remains the core pathological driver of preeclampsia. Defective placental implantation followed by dysfunctional placental spiral artery development promotes a hypoxic environment. Massive endothelial dysfunction characterized by reduced vasodilation, augmented vasoconstriction, and increased vascular permeability and inflammation ensues. Interestingly, the same signaling and inflammatory pathways implicated in preeclampsia appear to be shared with other vascular disorders involving alteration of α₂ -AR function. The role of α₂ -ARs in the regulation of microcirculatory function has long been recognized, thus raising the question of whether they are involved in the pathogenesis of vascular dysfunction in preeclampsia. Here, we review possible interplay between signaling and inflammatory pathways common to preeclampsia and α₂ -AR function/regulation. We speculate on the potential contribution of these receptors to the observed phenotype and the potential role for their pharmacological modulators as therapeutic interventions with preeclampsia.

Pregnancy before recurrent pregnancy loss more often complicated by post-term birth and perinatal death

INTRODUCTION

The cause of recurrent pregnancy loss often remains unknown. Possibly, pathophysiological pathways are shared with other pregnancy complications.

MATERIAL AND METHODS

All women with secondary recurrent pregnancy loss (SRPL) visiting Leiden University Medical Center (January 2000-2015) were included in this retrospective cohort to assess whether women with SRPL have a more complicated first pregnancy compared with control women. SRPL was defined as three or more consecutive pregnancy losses before 22 weeks of gestation, with a previous birth. The control group consisted of all Dutch nullipara delivering a singleton (January 2000-2015). Information was obtained from the Dutch Perinatal Registry. Outcomes were preeclampsia, preterm birth, post-term birth, intrauterine growth restriction, breach position, induction of labor, cesarean section, congenital abnormalities, perinatal death and severe hemorrhage in the first ongoing pregnancy. Subgroup analyses were performed for women with idiopathic SRPL and for women ≤35 years.

RESULTS

In all, 172 women with SRPL and 1 196 178 control women were included. Women with SRPL were older and had a higher body mass index; 29.7 years vs. 28.8 years and 25.1 kg/m² vs. 24.1 kg/m² , respectively. Women with SRPL more often had a post-term birth (OR 1.86, 95% CI 1.10-3.17) and more perinatal deaths occurred in women with SRPL compared with the control group (OR 5.03, 95% CI 2.48-10.2). Similar results were found in both subgroup analyses.

CONCLUSIONS

The first ongoing pregnancy of women with (idiopathic) SRPL is more often complicated by post-term birth and perinatal death. Revealing possible links between SRPL and these pregnancy complications might lead to a better understanding of underlying pathophysiology.

Toxicological effects of the different substances in tobacco smoke on human embryonic development by a systems chemo-biology approach

The physiological and molecular effects of tobacco smoke in adult humans and the development of cancer have been well described. In contrast, how tobacco smoke affects embryonic development remains poorly understood. Morphological studies of the fetuses of smoking pregnant women have shown various physical deformities induced by constant fetal exposure to tobacco components, especially nicotine. In addition, nicotine exposure decreases fetal body weight and bone/cartilage growth in addition to decreasing cranial diameter and tibia length. Unfortunately, the molecular pathways leading to these morphological anomalies are not completely understood. In this study, we applied interactome data mining tools and small compound interaction networks to elucidate possible molecular pathways associated with the effects of tobacco smoke components during embryonic development in pregnant female smokers. Our analysis showed a relationship between nicotine and 50 additional harmful substances involved in a variety of biological process that can cause abnormal proliferation, impaired cell differentiation, and increased oxidative stress. We also describe how nicotine can negatively affect retinoic acid signaling and cell differentiation through inhibition of retinoic acid receptors. In addition, nicotine causes a stress reaction and/or a pro-inflammatory response that inhibits the agonistic action of retinoic acid. Moreover, we show that the effect of cigarette smoke on the developing fetus could represent systemic and aggressive impacts in the short term, causing malformations during certain stages of development. Our work provides the first approach describing how different tobacco constituents affect a broad range of biological process in human embryonic development.

Expression levels of cyclooxygenase-2, tumor necrosis factor-α and inducible NO synthase in placental tissue of normal and preeclamptic pregnancies

OBJECTIVE

Although preeclampsia (PE) is one of the most important problems affecting pregnant women, etiologic factors in its development are still unclear. We aimed to investigate the expression levels of cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α) and inducible NO synthase (iNOS) in preeclamptic and healthy control placentas.

PATIENTS AND METHODS

Placental tissue samples were obtained after delivery from patients diagnosed with PE and from normal-term pregnants and analyzed for COX-2, TNF-α and iNOS expression by immunohistochemistry.

RESULTS

A strong expression of COX-2 was observed in syncytiotrophoblast cells of preeclamptic placentas, which was significantly higher than that of normal placentas (p = 0.005). A mild expression of TNF-α in both normal and preeclamptic syncytiotrophoblasts was seen (p = 0.435). In addition, a strong expression of iNOS in normal syncytiotrophoblasts was found, but the intensity of the iNOS expression was highly reduced in preeclamptic placentas (p = 0.001). No correlation was detected between COX-2, TNF-α and iNOS expression levels.

CONCLUSION

The findings of a decrease of iNOS expression and an increase of COX-2 expression in placenta suggest the existence of functional roles of iNOS and COX-2 in the pathophysiology of PE, probably by contributing to the reduced placental blood flow and increased resistance to flow in the fetomaternal circulation.

Mammary uptake and excretion of prostanoids in relation to mammary blood flow and milk yield during pregnancy-lactation and somatotropin treatment in dairy goats

Mammary arterious-venous differences (A-V) and excretion into milk of four prostanoids were related to changes in milk yield and milk vein blood velocity (MBV) in goats at different stages of pregnancy and lactation, and during somatotropin (ST) treatment in mid-lactation. Arterial concentrations and mammary A-V for the vasodilators prostacyclin (PGI(2)) and prostaglandin (PG) E(2) (measured as 6-keto-PGF(1 alpha) and bicyclic PGE(2), respectively) decreased from late pregnancy to lactation. A-V were negatively correlated to MBV (r = -0.32 to -0.34). Arterial concentrations of the vasoconstrictors PGF(2 alpha) and TXA(2) (measured as TXB(2)) changed similarly, but no A-V across the mammary gland were found. The vasodilator to vasoconstrictor ratio in plasma was around 1:1, and in skimmed milk around 0.29-0.49 due to significantly higher TXB(2) levels in milk compared to plasma. Close linear correlations were established between milk yield and excretion of TXB(2) into milk (r = 0.80, P < 0.001), and between MBV and PGE(2) excretion into milk (r = 0.69, P < 0.001). ST treatment stimulated MBV and mammary prostanoid supply, and decreased prostanoid concentration in milk vein plasma. The high arterial levels of prostaglandins during pregnancy most likely reflected uterine synthesis. Our results support a role for PGI(2) and PGE(2) in local mammary blood flow regulation during lactation. Increased mammary uptake of these two prostanoids may be involved in the mammary blood flow response to ST. TXA(2) may be synthesized by mammary epithelial as well as vascular cells, and TXA(2) may be an important factor in regulation of mammary function.

Thyroid hormone alteration in pre-eclamptic women

This study sought a possible relationship between pre-eclampsia and thyroid profile. In a case-control setting, total thyroxine (T4), total tri-iodothyronine (T3), free T4, free T3, thyroxine binding globulin (TBG) and thyrotropin (TSH) levels in 39 pre-eclamptic patients were measured and compared with the levels in 42 healthy controls. We examined possible variations with regard to the severity of pre-eclampsia by dividing cases into mild (n = 17) and severe (n = 22) subgroups. Patients with mild pre-eclampsia showed significantly increased free T4 and TSH levels compared to healthy controls. In severe cases, TSH level was higher, but free T3 and free T4 levels were significantly lower than in controls. Other tests returned non-significant differences between the groups. Our findings suggest that primary hypofunctioning of the thyroid can accompany mild pre-eclampsia and possibly contribute to the pathogenesis. Elevated levels of free thyroid hormones in severe cases, however, may have reflected a preceding thyroid disorder.

Spontaneous resolution of aneurysmal third nerve palsy

Palsy of the third cranial nerve developed in a 33-year-old woman in her third trimester of pregnancy as a result of compression by a posterior communicating artery aneurysm. Prepartum complications forced postponement of surgical treatment. The palsy spontaneously resolved over 3 weeks after delivery by cesarean section. Repeat angiography suggested that the aneurysmal sac had shrunk. Spontaneous complete resolution of a third nerve palsy does not exclude an aneurysmal cause.

Normalization of vasoactive changes in preeclampsia precedes clinical recovery

OBJECTIVE

The objective of this study is to compare the serum levels of fibronectin, nitric oxide (NO), cyclic guanosine-monophosphate, endothelin-1, and 6-keto-prostaglandin-F 1alpha in women with and without preeclampsia before and after delivery.

METHODS

We studied 20 singleton pregnancies complicated by preeclampsia, and 20 women undergoing elective cesarean delivery were selected as controls. The normalization of circulating concentrations of maternal plasma NO, cyclic guanosine-monophosphate, fibronectin, endothelin-1, thromboxane-B 2 and renin, and urinary 6-keto-prostaglandin-F 1alpha after delivery was evaluated.

RESULTS

Mean systolic and diastolic blood pressure (BP) in the puerperium of preeclamptic women remained high after discharge from hospital, and only circulating fibronectin levels were found to be elevated in affected women at the end of hospital stay 5 days after delivery. Normalization of the imbalance in vasoactive substances and renal impairment in preeclampsia occur more rapidly than the patient's clinical recovery, within 2-3 days postpartum.

CONCLUSIONS

Slow normalization of circulating fibronectin concentrations reflects slow recovery of endothelial damage in preeclampsia, which may play a major role in maintaining high BP in the puerperium. Plasma levels of endothelin-1 declined to normal levels by the third postpartum day and the finding is consistent with the hypothesis that endothelin-1 is not the major vasoconstrictor in the pathophysiology of preeclampsia.

Increased thromboxane production in women with a history of venous thromboembolic event: effect of heparins

We investigated the production of prostacyclin and thromboxane in pregnant women with a previous venous thromboembolic event before, during and after the use of unfractionated heparin and low molecular weight heparin (dalteparin). Twenty women were studied before starting heparin prophylaxis (before 20 weeks of gestation), during heparin prophylaxis (at 30 weeks of gestation) and after heparin prophylaxis (16 weeks after delivery). Ten pregnant women with no history of thromboembolism were studied as the control group. Urinary output of the stable metabolite of prostacyclin (2,3-dinor-6-keto-PGF1alpha) and that of thromboxane A2 (2,3-dinor-TxB2), as well as a number of markers of thrombophilia were measured and expressed as mean (+/-SEM). Women with a history of thromboembolism were characterized by normal prostacyclin production but elevated thromboxane production (44.0 +/- 4.1 versus 19.0 +/- 3.6 ng/mmol creatinine, P < 0.001) at 12 weeks of pregnancy. Heparin prophylaxis (regardless of the type) had abolished elevated thromboxane concentrations at 30 weeks of gestation. Four months after delivery, thromboxane dominance had returned (25.2 +/- 3.5 versus 13.6 +/- 2.1 ng/mmol creatinine, P < 0.01). The presence of hereditary thrombophilia (9/20) was not associated with any changes in prostanoid concentrations. Thus, women with a history of venous thromboembolic events have thromboxane dominance during and after pregnancy, but this dominance can be eliminated through the use of heparins.

Pathophysiology of preeclampsia and the role of serotonin

Hypertensive disorders constitute the most common medical complications of pregnancy. In normal pregnancy, impressive physiological changes take place in the maternal cardiovascular system. Morphological changes are the result of invasion of migratory trophoblast cells into the walls of the spiral arteries. After destruction of elastic, muscular and neural tissue in the media, the trophoblast cells get incorporated into the vessel wall and the endothelial lining of the spiral arteries is restored. The physiological changes create a low-resistance, low-pressure, high-flow system with the absence of maternal vasomotor control. Biochemical adaptations in maternal vasculature include changes in the prostaglandin system, the renin-angiotensin-aldosteron system and the kallikrein-kinin system. In preeclampsia, physiological changes in the spiral arteries are confined to the decidual portion of the arteries. Myometrial segments remain anatomically intact and fail to dilate. In addition, the adrenergic nerve supply is left intact. The cause of this impaired endovascular trophoblast invasion is not yet elucidated. But in combination with the imbalance between vasodilator and vasoconstrictor eicosanoids, it gives rise to reduced perfusion of the intervillous space. In the absence of an adequate production of antiaggregatory prostacyclin (PGI(2)), nitric oxide, or both, surface-mediated platelet activation is supposed to occur on the surface of the spiral arteries. Because platelets are the principal source of circulating serotonin, the increased platelet aggregation in preeclampsia causes an increase in serotonin levels. Interaction of serotonin with serotonin(1)- or serotonin(2)-receptors depends on the state of the endovascular trophoblast or endothelium in the spiral arteries and has opposite effects with regard to vasodilating and vasoconstrictive influences.

Blood pressure and vasoactive hormones in mild preeclampsia and normal pregnancy

OBJECTIVE

Changes in vasoactive hormones are reported to play an important role in the pathogenesis of preeclampsia linking placental hypoperfusion with hypertension, systemic disease, and proteinuria. We, therefore, studied diurnal patterns of vasoactive hormones in mild preeclampsia.

METHODS

Venous blood samples were drawn every 2 h over 25 h for measurements of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), norepinephrine, renin activity, and aldosterone and two urine collections (12 h each) for stable prostaglandin metabolite measurements. The patients were nine women with mild preeclampsia and, for comparison, nine control women matched for gestation and parity.

RESULTS

Women with mild preeclampsia had higher norepinephrine levels throughout 25 h, and lower systemic prostacyclin production as measured by the urinary 2,3-dinor-6-keto PGF1 alpha excretion during the daytime. Plasma endothelin and ANP and BNP concentrations tended to be higher throughout 25 h in preeclampsia, but differences between the two groups did not reach levels of statistical significance. Plasma renin activity and aldosterone did not differ between the groups. Whereas control women exhibited a diurnal variation in plasma norepinephrine, ANP, BNP, and aldosterone, and in both urinary prostacyclin and thromboxane A2 metabolites, this was less distinct or absent in patients with mild preeclampsia.

CONCLUSIONS

We conclude that mild preeclampsia is associated with elevated plasma norepinephrine levels, lower systemic daytime production of prostacyclin, and blunting of the normal diurnal variation for a number of indices including plasma levels of BNP, ANP, norepinephrine, and aldosterone, and urinary prostacyclin metabolites.

Smoking and blood pressure patterns in normotensive pregnant women

This paper examines the relationship between smoking levels and blood pressure patterns of normotensive pregnant women in a prospective cohort of 2193 primiparous and 3176 multiparous, normotensive, Caucasian women selected from the Child Health and Development Studies in Oakland, California, 1959-67. Regression lines were fitted to each woman's blood pressure; mean intercept and slope estimates of the individual regressions were used to create summary profile lines for each smoking dose. Multivariable regression analysis controlled for maternal age, number of visits to the doctor after 20 weeks' gestation, body mass index and maternal education level. Overall, smokers had lower average diastolic blood pressure (smokers vs. nonsmokers adjusted mean: primiparas, 66.1 vs. 67.2 mmHg; and multiparas, 64.0 vs. 64.7 mmHg) but higher systolic blood pressure (smokers vs. nonsmokers adjusted mean: primiparas, 117.0 vs. 116.0; and multiparas, 112.5 vs. 110.0) than nonsmokers among primiparous and multiparous pregnant women after adjusting for potential confounders. However, these differences are small and there was no clear dose-response relationship between smoking level and blood pressure.

Cocaine does not affect prostacyclin, thromboxane or prostaglandin E production in human umbilical veins

Vasoactive prostaglandins have been reported to mediate umbilical/placental blood flow in humans. Since it has been suggested that cocaine exerts its teratogenic action via vasoconstriction and a corresponding reduction in blood flow, it is reasonable to hypothesize that cocaine influences the vasoactive prostaglandins such that blood flow would be affected. The purpose of this study, therefore, was to determine the effects of cocaine on the vasoactive prostaglandins prostacyclin, thromboxane, and prostaglandin E, using human umbilical veins. Prostacyclin (PGI2), thromboxane (TXA2), and prostaglandin E (PGE) levels were measured from human umbilical veins collected at term. The veins were perfused in a closed system with either a 50 micrograms/ml, a 100 micrograms/ml, a 200 micrograms/ml, or a 400 micrograms/ml cocaine solution for 60 min, and the prostaglandins were measured by radioimmunoassay of their stable metabolites. Data were analyzed by ANOVA, and post-hoc analyses were performed by Fisher's Protected Least Significant Difference Test. Cocaine did not influence PGI2, TXA2, or PGE production (Ps > 0.05) in this series of studies. Thus, contraction of human umbilical vessels and decreased blood flow in human umbilical vessels does not appear to be mediated by changes in the vasoactive prostaglandins.

The calcium-dependent nitric oxide production of human vascular endothelial cells in preeclampsia

OBJECTIVE

Nitric oxide is an important vasodilator, and in this study we studied whether the calcium-dependent nitric oxide production capacity of human umbilical vein endothelial cells was affected by preeclampsia.

STUDY DESIGN

Human umbilical vein endothelial cells were isolated from 11 preeclamptic and 10 normotensive pregnancies. The maximal calcium ionophore A23187-stimulated nitric oxide production capacity was measured as accumulation of nitrate and nitrite into the culture medium, and it was related to the number of viable endothelial cells by measurement of their mitochondrial dehydrogenase activity.

RESULTS

The cell number-related nitric oxide production capacity was similar in preeclamptic and normotensive pregnancies. The total nitric oxide production of cells from preeclamptic pregnancies was significantly lower (p <0.001). This difference, however, was mainly caused by larger amount of viable endothelial cells recovered from normotensive pregnancies.

CONCLUSION

The maximal calcium-dependent nitric oxide production capacity of individual human umbilical vein endothelial cells is not affected by preeclampsia.

Alterations of intrauterine eicosanoid production in pregnancy-induced hypertension: decreased production of 12-hydroxyeicosatetraenoic acid in the placenta

The important role of eicosanoids in pregnancy-induced hypertension is generally accepted. Because of the lack of innervation of the uteroplacental vessels, humoral vasoactive factors are important for the regulation of vascular tone. Until now, mainly the balance of vasodilatative and vasoconstrictive prostaglandins has been studied. We were able to confirm their intrauterine imbalance in hypertensive pregnancies. In addition, the placental production of less known lipoxygenase metabolites has been analyzed in this study. Intrauterine tissues (30-100mg wet weight) were examined for their release of eicosanoids. Short term tissue cultures were performed in Hanks balanced salts solution (HBSS) at 37 degrees C in an atmosphere of 95% air/5% CO2 with and without incorporation of tritiated arachidonic acid. The arachidonate metabolites in culture media were analyzed by High Performance Liquid Chromatography (HPLC) with radioactivity detection or by enzyme immunoassays or radioimmunoassays, respectively. All intrauterine tissues released more lipoxygenase metabolites than cyclooxygenase metabolites with 12-hydroxy-eicosatetraenic acid (12-HETE) as their main metabolite. The placental release of 12-HETE was significantly decreased in hypertensive pregnancies. In hypertensive pregnancies the ratio TXB2/6-keto-PGF1 alpha synthesis was increased. Lipoxygenase metabolites, especially 12-HETE, seem to have important physiological and pathophysiological functions in the intrauterine compartment. Their biological role in this context needs further investigation.

Effect of ethanol on prostacyclin, thromboxane, and prostaglandin E production in human umbilical veins

The purpose of this study was to determine the effects of ethanol on prostacyclin (PGI2), prostaglandin E (PGE), and thromboxane (TXA2) production in perfused human umbilical veins. PGI2, PGE, and TXA2 levels were measured from human umbilical veins perfused with either 25, 50, or 100 mM ethanol by radioimmunoassay of their stable metabolites. Alcohol content was measured by an enzymatic spectrophotometric assay. Data were analyzed by ANOVA and Fisher's Protected Least Significant Difference Test. Ethanol decreased PGI2 production in a concentration-dependent manner (p < 0.05). In a concentration of 25 mM, ethanol did not affect PGI2 production, whereas 50 mM decreased levels after 60 min of perfusion (p < 0.01). With 100 mM ethanol, PGI2 production was decreased after 15, 30, and 60 min of perfusion (ps < 0.05), and the TXA2/PGI2 ratio was significantly elevated at all time points (p < 0.01). Ethanol (100 mM) did not affect TXA2 or PGE production. Reduction of PGI2 levels and the increase in the TXA2/PGI2 ratio seen after ethanol perfusion in umbilical veins may cause vascular disruption in the umbilical-placental circulation. This may, in part, be a contributing mechanism to the teratogenic effects of ethanol.

Dietary supplementation with primrose oil or fish oil does not change urinary excretion of prostacyclin and thromboxane metabolites in pre-eclamptic women

To study whether balance between antiaggregatory, vasodilatory prostacyclin (PGI2) and proaggregatory, vasoconstrictory thromboxane A2 (TXA2) could be affected by dietary manipulation, 18 pre-eclamptic women were treated in randomized order between 31 and 36 weeks of gestation either with primrose oil (n = 7), with fish oil (n = 5), or with placebo (n = 6). Urinary excretions of the degradation products of PGI2 (6-keto-PGF1 alpha, 2,3-dinor-6-keto-PGF1 alpha) and TXA2 (TXB2, 2,3-dinor-TXB2) were measured in 24 h urines before and serially during the supplementation. Fatty acid supplementation did not affect urinary prostanoid excretions or clinical signs of pre-eclampsia.