Corticotrophin-releasing hormone production by the placenta and fetal membranes

Maternal Sociodemographic Factors and Antenatal Stress

Antenatal stress has been associated with adverse birth outcomes such as fetal growth restriction, low birth weight, and preterm birth. Understanding key determinants of stress in a vulnerable pregnant population has the potential of informing development of targeted cost-effective interventions to mitigate against these adverse birth outcomes. We conducted a secondary analysis of data from 150 pregnant women attending antenatal care services at a rural referral hospital in Kenya. The participants completed a sociodemographic and clinical questionnaire, the Cohen’s Perceived Stress Scale (PSS) and gave a hair sample for cortisol and cortisone analysis. The association between selected sociodemographic predictors (age, parity, marital status, maternal education, household income, polygyny, and intimate partner violence) and outcomes (hair cortisol, hair cortisone, and PSS score) was examined using univariate, bivariate and multivariate models. We found a negative association between PSS scores and household income (β = −2.40, p = 0.016, 95% CI = −4.36, −0.45). There was a positive association of the ratio of hair cortisone to cortisol with Adolescent age group (β = 0.64, p = 0.031, 95% CI = 0.06, 1.22), and a negative association with Cohabitation (β = −1.21, p = 0.009, 95% CI = −2.11, −0.31). We conclude that household income influenced psychological stress in pregnancy. Adolescence and cohabitation may have an influence on biological stress, but the nature of this effect is unclear.

Placental FKBP51 mediates a link between second trimester maternal anxiety and birthweight in female infants

Prenatal distress is associated with adverse outcomes in affected offspring. Alterations in placental glucocorticoid signalling and subsequent foetal overexposure to glucocorticoids have been implicated as an underlying mechanism. Infant sex is emerging as an important factor in disease susceptibility. This study aimed to examine the effects of maternal distress across pregnancy on birth outcomes and placental glucocorticoid genes in a sex-dependent manner. Participants completed psychological distress questionnaires throughout pregnancy. Placental HSD11B2, NR3C1 and FKBP51 were analysed by real time PCR and cortisol was measured in new-born hair. Second trimester stress was negatively correlated with birthweight in males and positively correlated with placental NR3C1 mRNA in females. Second trimester anxiety was negatively correlated with birthweight and placental FKBP51 mRNA in females. In mediation analysis, placental FKBP51 mRNA expression was found to mediate the link between prenatal anxiety and birthweight. New-born cortisol was negatively correlated with second trimester anxiety and positively correlated with female placental FKBP51 mRNA levels. Again, FKBP51 mRNA was found to mediate the link between anxiety and new-born cortisol. These results highlight a role for FKBP51 in the placental response to prenatal distress in females. The precise role that placental FKBP51 has in foetal and infant development has not been extensively studied and warrants further investigations.

Lifetime Modulation of the Pain System via Neuroimmune and Neuroendocrine Interactions

Chronic pain is a debilitating condition that still is challenging both clinicians and researchers. Despite intense research, it is still not clear why some individuals develop chronic pain while others do not or how to heal this disease. In this review, we argue for a multisystem approach to understand chronic pain. Pain is not only to be viewed simply as a result of aberrant neuronal activity but also as a result of adverse early-life experiences that impact an individual's endocrine, immune, and nervous systems and changes which in turn program the pain system. First, we give an overview of the ontogeny of the central nervous system, endocrine, and immune systems and their windows of vulnerability. Thereafter, we summarize human and animal findings from our laboratories and others that point to an important role of the endocrine and immune systems in modulating pain sensitivity. Taking "early-life history" into account, together with the past and current immunological and endocrine status of chronic pain patients, is a necessary step to understand chronic pain pathophysiology and assist clinicians in tailoring the best therapeutic approach.

Cerebrospinal Fluid CRH Levels in Late Pregnancy Are Not Associated With New-Onset Postpartum Depressive Symptoms

CONTEXT

CRH participates in the hypothalamic-pituitary-adrenal axis and in neural circuits involved in the pathophysiology of depression. During pregnancy, the placenta produces large amounts of CRH, and production ceases abruptly after delivery. The relationship between CRH in the cerebrospinal fluid (CSF) during pregnancy and peripartum mood disorders has not been investigated.

OBJECTIVES

The objectives were to determine whether there are differences in CSF CRH concentrations of pregnant and nonpregnant women and whether CSF CRH concentrations in late pregnancy are associated with the presence of depressive symptoms during pregnancy and in the early postpartum period.

DESIGN

This was a prospective cohort study conducted from January to April, 2011.

SETTING

The study was conducted in one public and two private hospitals in Brasilia, Brazil.

PATIENTS

Patients included 107 healthy pregnant women who underwent elective cesarean delivery and 22 nonpregnant healthy women who underwent spinal anesthesia for elective surgical sterilization.

INTERVENTION

CRH in CSF was measured in pregnant and nonpregnant women by ELISA.

MAIN OUTCOME MEASURE

The association between CSF CRH concentration at delivery and maternal depression assessed before cesarean section and postpartum (4 to 8 wk) with the Edinburgh Postnatal Depression Scale (EPDS), with a cutoff of ≥ 13.

RESULTS

CRH concentration in the CSF was significantly higher in pregnant (4.1 ± 0.51 log CRH) than in nonpregnant women (3.6 ± 0.26 log CRH) (P < .001). Depressive symptoms starting after delivery occurred in 5.6% of women. CRH concentration in CSF was not different between women without depressive symptoms and women showing such symptoms during pregnancy or in the postpartum period.

CONCLUSION

CRH concentration in the CSF was higher in pregnant women than in nonpregnant women. However, in this sample, CSF CRH in late pregnancy was not associated with new-onset depressive symptoms in the early postpartum period.

Stress During Pregnancy

High levels of stress during pregnancy are associated with a number of adverse psychological and physiological outcomes for mother and child. These effects seem to be transmitted in part by one of the major stress-responsive systems, namely the hypothalamic-pituitary-adrenal (HPA) axis, which includes the hormone cortisol. However, as inconsistent study results indicate, methodology poses a substantial challenge to the investigation of stress during pregnancy. For example, although measures of maternal psychological stress and stress hormones are independently related to adverse pregnancy outcome, they seldom have been found to correlate with one another directly. Repeated measurement of psychological and biological responses to acute standardized stress challenges appears to reveal stronger associations. This article reviews the literature on experienced stress and stress hormones in pregnant women and presents studies that used standardized stress challenges (e.g., the Trier Social Stress Test, the cortisol response to morning awakening) to examine maternal stress reactivity more systematically. This review also takes a look at the few studies that examined the protective effects of psychological and psychosocial resources or stress interventions on experienced stress and stress hormones in pregnant women. Overall, results indicate that baseline stress hormone levels advance incrementally during gestation, presumably to prepare mother and fetus for delivery, while responses to acute stress appear to be increasingly attenuated. Moreover, the acute maternal stress response seems to be predictive of neonatal birth outcome and maternal well-being postpartum. Preliminary findings also suggest that much can be done toward coping with stress during pregnancy. Further research and a closer collaboration between science and clinical practice are required.

Context modulates outcome of perinatal glucocorticoid action in the brain

Prematurely born infants may be at risk, because of inadequate maturation of tissues. If there are signs of preterm birth, it has become common practice therefore to treat either antenatally the mother or postnatally the infant with glucocorticoids to accelerate tissue development, particularly of the lung. However, this life-saving early glucocorticoid treatment was found to increase the risk of adverse outcome in later life. In one animal study, the authors reported a 25% shorter lifespan of rats treated as newborns with the synthetic glucocorticoid dexamethasone, but so far this finding has not been replicated. After a brief clinical introduction, we discuss studies in rodents designed to examine how perinatal glucocorticoid action affects the developing brain. It appears that the perinatal action of the glucocorticoid depends on the context and the timing as well as the type of administered steroid. The type of steroid is important because the endogenous glucocorticoids cortisol and corticosterone bind to two distinct receptor populations, i.e., mineralocorticoid and glucocorticoid receptors (GR), while synthetic glucocorticoids predominantly bind to the GR. In addition, if given antenatally hydrocortisone is inactivated in the placenta by 11β-HSD type 2, and dexamethasone is not. With respect to timing, the outcome of glucocorticoid effects is different in early vs. late phases of brain development. The context refers to the environmental input that can affect the susceptibility to glucocorticoid action in the newborn rodent brain; early handling of pups and maternal care obliterate effects of post-natal dexamethasone treatment. Context also refers to coping with environmental conditions in later life, for which the individual may have been programed epigenetically by early-life experience. This knowledge of determinants affecting the outcome of perinatal glucocorticoid exposure may have clinical implications for the treatment of prematurely born infants.

Regulation of estradiol and progesterone production by CRH-R1 and -R2 is through divergent signaling pathways in cultured human placental trophoblasts

CRH and its related peptides urocortins (UCN) have been identified in placenta and implicated to play pivotal roles in the regulation of pregnancy and parturition in humans. The objectives of present study were to investigate the effects of endogenous CRH and its related peptides in the regulation of steroid production in placenta. Placental trophoblasts were isolated from term placenta tissues and cultured for 72 h. Estradiol (E(2)) and progesterone (P(4)) contents in culture media were determined by radioimmunoassay. Treatment of cultured trophoblasts with CRH or UCNI antibody showed decreased E(2), whereas increased P(4) production. Treatment of cells with CRH receptor type 1 antagonist antalarmin or CRH receptor type 2 (CRH-R2) antagonist astressin-2b also decreased E(2) but increased P(4) production. Knockdown of CRH receptor type 1 or CRH-R2 cells showed a decrease in E(2) production and an increase in P(4) production. In CRH-R2 knockdown cells, CRH stimulated GTP-bound Gαs protein and phosphorylated phospholipase C-β3. Adenylyl cyclase and protein kinase A inhibitors blocked CRH-induced increased E(2) production but not decreased P(4) production. PLC inhibitor U73122 and protein kinase C inhibitor chelerythrine blocked the effects of CRH on E(2) and P(4) production in CRH-R2 knockdown cells. UCNIII, the specific CRH-R2 agonist, stimulated GTP-bound Gαi protein and phosphorylated phospholipase C-β3 expression. Both U73122 and chelerythrine blocked UCNIII-induced increased E(2) production and decreased P(4) production. We suggest that CRH and its related peptides might be involved in changes in the progesterone to estrogen ratio during human pregnancy.

Endocrine-immune interactions in pregnant non-human primates with intrauterine infection

Preterm birth remains the most common cause of perinatal mortality. Although the causes of preterm labor are multifactorial and vary according to gestational age, preterm labor and term labor share common cellular and molecular mechanisms, including stimulation of the fetal hypothalamic-pituitary-adrenal (HPA) axis and endocrine/immune system interactions. We have developed a non-human primate experimental model for intrauterine infection and preterm labor using chronically instrumented rhesus monkeys (Macaca mulatta) with timed gestations. We have documented the temporal and quantitative relationships among intrauterine infection, the synthesis and release of proinflammatory cytokines, prostaglandins, and fetal-placental steroid biosynthesis in this model. Infection-induced preterm parturition is characterized by significant elevations in amniotic fluid proinflammatory cytokines and by increases in fetal adrenal steroid biosynthesis, but not by corresponding increases in placental estrogen biosynthesis characteristic of spontaneous parturition. This suggests that activation of the fetal HPA axis by the stress of infection is accompanied by placental dysfunction and also that infection-induced preterm parturition is not dependent upon the increased estrogen biosynthesis observed in spontaneous parturition. These different endocrine and immune responses have important diagnostic and therapeutic implications in the management of preterm labor.

CRH acts on CRH-R1 and -R2 to differentially modulate the expression of large-conductance calcium-activated potassium channels in human pregnant myometrium

CRH has been implicated to play a key role in the control of human pregnancy and parturition. Large-conductance potassium channels (BKCa) play a pivotal role in the modulation of uterine contractility during pregnancy. The objectives of the present study were to investigate the effect of CRH on BKCa expression in human pregnant myometrial cells. Myometrial tissues were collected at cesarean section from pregnant women not-in-labor (TNL) or in-labor (TL) at term, and myocytes were isolated and cultured. CRH was identified in human pregnant myometrium and mainly expressed in myometrial myocytes. Cultured myometrial cells were able to secrete CRH. In TNL myometrial cells, CRH treatment increased the expression of BKCa α- and β-subunits. CRH receptor type 1 (CRH-R1) antagonist, antalarmin, decreased whereas CRH receptor type 2 (CRH-R2) antagonist, astressin2b, increased the expression of BKCa. CRH-R2 small interfering RNA (siRNA) caused an increase, but CRH-R1 siRNA resulted in a decrease, in BKCa expression. In contrast to TNL cells, CRH exhibited an opposite effect on BKCa expression in TL myometrial cells, i.e. decreased BKCa expression. Antalarmin enhanced but astressin2b reduced BKCa expression. CRH-R2 siRNA decreased whereas CRH-R1 siRNA increased BKCa expression. 1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one significantly inhibited the frequency of spontaneous contractions of myometrial strips, and this effect was significantly decreased in TL strips compared with TNL ones. Our data suggest that CRH-R1 and CRH-R2 show differential regulation of BKCa expression. These effects mediated by CRH-R1 and CRH-R2 are changed after the onset of labor. This leads us to suggest that CRH may fine-tune myometrial contractility by modulating the expression of BKCa during pregnancy and labor.

Terbutaline inhibits corticotropin-releasing hormone (CRH) expression in human trophoblast cells

OBJECTIVE

To evaluate the effect of beta-adrenergic agonists on the regulation of the expression of the placental corticotropin-releasing hormone (CRH) gene.

STUDY DESIGN

Term placentae were collected at the time of elective cesarean section, and trophoblast cells were harvested, isolated, and cultured. The isolated trophoblasts were plated, cultured and subsequently treated with cortisol, terbutaline, RU486, or vehicle control. CRH expression, mRNA abundance of CRH, and the housekeeping gene beta-actin were evaluated by Northern blot analysis.

RESULTS

Exposure of the trophoblasts to terbutaline (10(-8) M) inhibited the expression of the CRH gene as depicted by Northern blot analysis. Co-addition of terbutaline (10(-8) M) and RU486 (10(-6) M) did not block the stimulatory effects of RU486 on placental trophoblast cells.

CONCLUSION

The beta-adrenergic agonist terbutaline inhibits the expression of CRH in human trophoblasts. This finding may provide insight into the mechanism of action of terbutaline as a tocolytic agent.

Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour

BACKGROUND

Corticotropin-releasing hormone (CRH) and CRH-related peptide are shown to modulate uterine contractility through two CRH receptor subtype, CRH-R1 and CRH-R2 during pregnancy. Through different signaling pathways, CRH-R1 maintains myometrial quiescence whereas CRH-R2 promotes smooth muscle contractility. We hypothesized that the expression of CRH receptors in myometrium might be changed during pregnancy and labour.

METHOD

Immunohistochemistry, Western blot and RT-PCR were used to quantify the cellular localization, the protein levels and the mRNA variants of both CRH-R1 and CRH-R2 in upper segment (US) and lower segment (LS) myometrium from nonpregnant and pregnant women at term before or after labour.

RESULTS

CRH-R1 and CRH-R2 were predominately localized to myometrial smooth muscle cells in US and LS. The protein level of CRH-R1 in US was significantly down-regulated in pregnancy, with a further decrease at the onset of labour. However, the expression of CRH-R1 in LS remained unchanged during pregnancy and labour. No significant changes in CRH-R2 expression were observed in US or LS. Six variants of CRH-R1, CRH-R1alpha,-R1beta,-R1c, -R1e,-R1f and -R1g, were identified in nonpregnant and pregnant myometrium. CRH-R2alpha was identified in pregnant myometrium, whereas CRH-R2beta was identified in nonpregnant myometrium

CONCLUSION

CRH-R1 and CRH-R2 are expressed in nonpregnant and pregnant US and LS myometrium. Changed expression of CRH receptors during labour may underlie the initiation of uterine contractility during parturition.

Endocrinology of labour

Preterm labour, defined as delivery before 37 weeks of completed pregnancy, continues to present a major problem in clinical obstetrics and remains the major contributory factor to the perinatal mortality and morbidity statistics. While it is now possible, with recent advances in neonatal care, to take infants delivered very prematurely and provide them with the lifelines that will ensure their ultimate discharge from the neonatal intensive care nursery, the cost of this form of management – in terms both of health care funds and of emotion – is extraordinarily high. Hence there remains a strong rationale for attempting to understand the underlying biochemistry and physiology of labour in order to develop methods of recognizing the patient in true preterm labour, and of developing better strategies to prevent or to manage this condition. In the best of our neonatal intensive care settings, survival of the infant born at 28–30 weeks’ gestation, or greater than 1500 grams, may be greater than 90%. Thus, the clinical management strategy may be directed more towards sustaining intrauterine life for 4–6 weeks in those patients presenting in preterm labour before this time in order to gain time for intrauterine maturation of these fetuses before they are delivered to the tertiary care NICU setting.

Corticotropin Releasing Hormone Modulates Endotoxin-Induced Inflammatory Cytokine Expression in Human Trophoblast Cells

Recent studies have suggested a significant increase in corticotropin releasing hormone (CRH) in maternal plasma and placenta during the course of maternal infection. The aim of this study was to examine the possible role of CRH in lipopolysaccharide (LPS)-induced pro-inflammatory cytokine expression using the well-established human extravillous trophoblast cell line HTR-8/SVneo. Exposure of the HTR-8/SVneo cells to LPS resulted in increased secretion of tumour necrosis factor alpha (TNF-alpha) and interleukin (IL)-8. Pre-treatment of the cells with CRH prior to LPS exposure significantly enhanced LPS induced TNF-alpha and IL-8 secretion. This effect was inhibited by the CRH antagonist astressin. Stimulation of the cells with CRH caused a rapid and transient phosphorylation of p38/MAPK while CRH had no effect on ERK1/2 activation. The effect of CRH on p38/MAPK activation was suppressed by astressin and by the p38/MAPK inhibitor SB203580. Exposure of the cells to CRH resulted in increased expression of TLR-4 and this effect was also inhibited by astressin. Taken together, these findings suggest that CRH augments LPS induced cytokine secretion in human trophoblast cells. Modulation of LPS induced immune responses by CRH may be mediated through regulation of TLR-4 and selective activation of the p38/MAPK signalling pathway.

The effect of depression, anxiety and early life trauma on the cortisol awakening response during pregnancy: preliminary results

The purpose of this study was to examine the effects of maternal depression and anxiety on the cortisol awakening response (CAR), a marker of the hypothalamic-pituitary-adrenal (HPA) axis function, during pregnancy. Sixty-six pregnant women were studied between 25 and 33 weeks of gestation and were identified as either Depressed (n=33) or healthy, Control (n=33), based on depression scores and lifetime psychiatric history. Saliva samples were collected (passive drool) upon awakening and at +30 and +60 min thereafter. The CAR was not significantly different between women who were depressed during pregnancy compared to healthy control women. However, women taking antidepressant (AD) medication showed an attenuated CAR (time x AD use interaction, p=0.06). Childhood maltreatment (as measured with the Childhood Trauma Questionnaire) was associated with a lower baseline cortisol concentration explaining 12% of the variance, controlling for wake-up time and AD use. There is a complex interplay of factors involved in the HPA axis regulation of vulnerable women during pregnancy, including depression, anxiety, early life stress and psychotropic medication use, which remain unclear. The CAR may provide important information about the maternal HPA axis during pregnancy and warrants further investigation in larger cohorts.

Corticotropin-releasing hormone receptor type 1 and type 2 mediate differential effects on 15-hydroxy prostaglandin dehydrogenase expression in cultured human chorion trophoblasts

Throughout gestation, the chorion laeve controls the levels of biologically active prostaglandins (PGs) by its high level of nicotinamide adenine dinucleotide-dependent 15-hydroxy PG dehydrogenase (PGDH). In this study, we investigate the effects mediated by CRH receptors on the expression of PGDH in the chorion. We found that both CRHR1 and CRHR2 were localized in cultured chorion trophoblast cells, with CRH-R1alpha, R1beta, R1c, R1e, and R1f and CRHR2beta isoforms identified in these cells. To block the actions of endogenous CRH and its related peptides, cultured chorion trophoblasts were treated with an increasing concentration of alpha-helical CRH 9-41, the nonselective CRH receptor antagonist, which resulted in decreased mRNA and protein expression as well as the activity of PGDH. To investigate the individual role of CRHR1 and CRHR2, cell cultures were treated with the specific CRHR1 antagonist antalarmin and CRHR2 antagonist astressin2B, respectively. The results showed that antalarmin increased whereas astressin2B decreased mRNA and protein expression as well as the activity of PGDH in chorion cells. When the cells were treated with an exclusive CRHR2 agonist, urocortin II, elevated expression and activity of PGDH was exhibited. However, cells treated with either exogenous CRH or urocortin I showed significantly increased PGDH expression, and these effects could be blocked by astressin2B but not by antalarmin. We suggest that, in chorion trophoblast cells, CRHR1 and CRHR2 mediate divergent effects on PGDH expression, and this may provide a precise regulation of PGs levels from chorion to myometrium during pregnancy.

Association between serum tumor necrosis factor-? and corticotropin-releasing hormone levels in women with preterm labor

AIM

To evaluate the association of serum corticotropin-releasing hormone (CRH) and tumor necrosis factor-alpha (TNF-alpha) in preterm labor.

METHODS

Forty-nine primigravidas with a singleton viable pregnancy between 28 and 34 weeks of gestation were studied. They were divided into two groups. Group A consisted of 30 pregnant women (mean gestational age: 30.6 week) who presented with preterm labor and group B consisted of 19 pregnant women (mean gestational age: 29.8 week) with normal pregnancies.

RESULTS

Women of group A had significantly higher serum CRH levels compared to those of group B (P < 0.01). Similarly, serum TNF-alpha levels were significantly higher in women of group A when compared to women of group B (7.8 +/- 3.72 pg/mL and 5.1 +/- 3.72 pg/mL, respectively). Furthermore, a positive correlation was found between serum CRH and TNF-alpha levels in both groups, which was stronger in women of group A.

CONCLUSIONS

Our findings suggest that the increased levels of TNF-alpha and CRH found in pregnant women presenting with preterm labor may be involved in the pathophysiological mechanism of the latter. Furthermore, a positive interaction may exist between TNF-alpha and placental CRH, which may lead to enhanced production of the second and, therefore, facilitate the onset of labor.

The HPA axis and perinatal depression: a hypothesis

Episodes of depression and anxiety are as common during pregnancy as postpartum. Some start in pregnancy and resolve postpartum, others are triggered by parturition and some are maintained throughout. In order to determine any biological basis it is important to delineate these different subtypes. During pregnancy, as well as the rise in plasma oestrogen and progesterone there is a very large increase in plasma corticotropin releasing hormone (CRH), and an increase in cortisol. The latter reaches levels found in Cushing's syndrome and major melancholic depression. Levels of all these hormones drop rapidly on parturition.We here suggest that the symptoms of antenatal and postnatal depression may be different, and linked in part with differences in the function of the hypothalamic pituitary adrenal (HPA) axis. There are two subtypes of major depression, melancholic and atypical, with some differences in symptom profile, and these subtypes are associated with opposite changes in the HPA axis. Antenatal depression may be more melancholic and associated with the raised cortisol of pregnancy, whereas postnatal depression may be more atypical, triggered by cortisol withdrawal and associated with reduced cortisol levels. There is evidence that after delivery some women experience mild bipolar II depression, and others experience post traumatic stress disorder. Both of these are associated with atypical depression. It may also be that some women are genetically predisposed to depression of the melancholic type and some to depression of the atypical type. These women may be more or less vulnerable to depression at the different stages of the perinatal period.

Maternal anxiety at amniocentesis and plasma cortisol

OBJECTIVES

To assess whether anticipation of amniocentesis is linked with maternal anxiety, and whether this anxiety is associated with increased maternal plasma cortisol.

METHODS

Two hundred and fifty-four women awaiting a morning amniocentesis for karyotyping (gestation range 15-37 weeks, median 17 weeks) completed Spielberger state and trait anxiety inventory (STAI) questionnaires, and provided blood samples immediately before the procedure for cortisol assay. Six hundred and five women at mean gestation of 20 weeks, attending the same hospital for routine ultrasound but not for amniocentesis, also completed Spielberger STAI questionnaires and served as a comparison group for the anxiety ratings.

RESULTS

Mean state and trait anxiety scores (+/- SD) in the comparison group of 605 women at mean gestation of 20 weeks were 36.1 +/- 10.2 (range 20-70) and 35.6 +/- 8.9 (range 20-73), respectively. The mean state anxiety score (+/-SD) of 49.8 +/- 14.0 (range 20-77) of the amniocentesis group was considerably higher than the comparison group (p < 0.001), although the mean trait anxiety score in the amniocentesis group was similar at 36.4 +/- 8.6 (range 21-60). The state, but not trait, anxiety correlated with plasma cortisol (r = 0.176, p = 0.005). Maternal cortisol in the amniocentesis group increased with gestational age (r = 0.310, p < 0.001), whereas state anxiety scores showed no significant change with increase in gestational age (r = - 0.042, ns). Multivariate analysis demonstrated that maternal state anxiety was positively correlated with plasma cortisol independent of gestation and time of collection.

CONCLUSION

Women awaiting amniocentesis experience a high state anxiety associated with modestly increased plasma cortisol.

Physiological stress reactivity in human pregnancy—a review

Prenatal maternal stress has been found to have long-lasting effects on the behavioral and physiological development of the offspring. These programming effects on the fetus would be physiologically mediated through heightened and/or abnormal activity of the maternal sympathetic-adrenal-medullary system (SAM) and especially of her hypothalamic-pituitary-adrenocortical axis (HPA-axis). The abnormalities in maternal physiology could be present in her basal functioning, but also in her physiological reactivity to stressors, which constitutes the topic of this paper. This article reviews studies that have used laboratory challenges to study physiological stress reactivity in pregnant women. It concentrates on stress tests designed to produce pain or discomfort, or cognitive and psychological stress, and that assess changes in blood pressure, heart rate and/or cortisol as reactivity measures. The general conclusion is that physiological stress reactivity appears to be dampened during pregnancy. Nonetheless, the physiological responses to laboratory challenges are clearly present and display enough inter-individual variability to enable the study of links between responsivity patterns, psychosocial variables, fetal behavior, pregnancy outcome and offspring development. This paper also looks into the methodological limitations present in the reviewed studies. Options for sound design of stress test protocols are discussed and recommendations for future studies are presented. These methodological points are general and can therefore also be of use for researchers studying human stress reactivity in other populations and ages.

Maternal and fetal hypothalamic-pituitary-adrenal axes during pregnancy and postpartum

The principal modulators of the hypothalamic-pituitary-adrenal (HPA) axis are corticotropin-releasing hormone (CRH) and arginine-vasopressin (AVP). Corticotropin-releasing hormone is not exclusively produced in the hypothalamus. Its presence has been demonstrated at peripheral inflammatory sites. Ovulation and luteolysis bear characteristics of an aseptic inflammation. CRH was found in the theca and stromal cells as well as in cells of the corpora lutea of human and rat ovaries. The cytoplasm of the glandular epithelial cells of the endometrium has been shown to contain CRH and the myometrium contains specific CRH receptors. It has been suggested that CRH of fetal and maternal origin regulates FasL production, thus affecting the invasion (implantation) process through a local auto-paracrine regulatory loop involving the cytotrophoblast cells. Thus, the latter may regulate their own apoptosis. During pregnancy, the plasma level of circulating maternal immunoreactive CRH increases exponentially from the first trimester of gestation due to the CRH production in the placenta, decidua, and fetal membranes. The presence in plasma and amniotic fluid of a CRH-binding protein (CRHbp) that reduces the bioactivity of circulating CRH by binding is unique to humans. Maternal pituitary ACTH secretion and plasma ACTH levels rise during pregnancy-though remaining within normal limits-paralleling the rise of plasma cortisol levels. The maternal adrenal glands during pregnancy gradually become hypertrophic. Pregnancy is a transient, but physiologic, period of hypercortisolism. The diurnal variation of plasma cortisol levels is maintained in pregnancy, probably due to the secretion of AVP from the parvicellular paraventricular nuclei. CRH is detected in the fetal hypothalamus as early as the 12th week of gestation. CRH levels in fetal plasma are 50% less than in maternal plasma. The circulating fetal CRH is almost exclusively of placental origin. The placenta secretes CRH at a slower rate in the fetal compartment. AVP is detected in some neurons of the fetal hypothalamus together with CRH. AVP is usually detectable in the human fetal neurohypophysis at 11 to 12 weeks gestation and increases over 1000-fold over the next 12 to 16 weeks. The role of fetal AVP is unclear. Labor appears to be a stimulus for AVP release by the fetus. The processing of POMC differs in the anterior and intermediate lobes of the fetal pituitary gland. Corticotropin (ACTH) is detectable by radioimmunoassay in fetal plasma at 12 weeks gestation. Concentrations are higher before 34 weeks gestation, with a significant fall in late gestation. The human fetal adrenal is enormous relative to that of the adult organ. Adrenal steroid synthesis is increased in the fetus. The major steroid produced by the fetal adrenal zone is sulfoconjugated dehydroepiandrosterone (DHEAS). The majority of cortisol present in the fetal circulation appears to be of maternal origin, at least in the nonhuman primate. The fetal adrenal uses the large amounts of progesterone supplied by the placenta to make cortisol. Another source of cortisol for the fetus is the amniotic fluid where cortisol converted from cortisone by the choriodecidua, is found. In humans, maternal plasma CRH, ACTH, and cortisol levels increase during normal labor and drop at about four days postpartum; however, maternal ACTH and cortisol levels at this stage are not correlated. In sheep, placental CRH stimulates the fetal production of ACTH, which in turn leads to a surge of fetal cortisol secretion that precipitates parturition. The 10-day-long intravenous administration of antalarmin, a CRH receptor antagonist, significantly prolonged gestation compared to the control group of animals. Thus, CRH receptor antagonism in the fetus can also delay parturition. The HPA axis during the postpartum period gradually recovers from its activated state during pregnancy. The adrenals are mildly suppressed in a way analogous to postcure Cushing's syndrome. Provocation testing has shown that hypothalamic CRH secretion is transiently suppriently suppressed at three and six weeks postpartum, normalizing at 12 weeks.

Human fetal and maternal corticotrophin releasing hormone responses to acute stress

OBJECTIVES

To study the effect of acute stress, caused by intrauterine needling at the intrahepatic vein (IHV), on fetal plasma concentrations of corticotrophin releasing hormone (CRH), and to compare paired fetal and maternal samples for CRH concentration to determine the extent of their joint control.

DESIGN

Venous blood samples were obtained from fetuses (gestational age 17-38 weeks) undergoing fetal blood sampling (n = 29) or intrauterine transfusion (n = 17) through either the IHV or the placental cord insertion (PCI).

SETTING

The Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London, UK.

PATIENTS

Pregnant women undergoing clinically indicated fetal blood sampling or intrauterine blood/platelet transfusion.

RESULTS

Fetal plasma cortisol increased with intrahepatic vein transfusion (mean (SD) cortisol response Delta64.7 (54.5) nmol/l; p < 0.0001, n = 11), and fetal corticotrophin concentrations were higher after IHV (n = 7) than PCI needling (n = 6). Neither fetal nor maternal plasma CRH increased after IHV transfusion. Fetal CRH levels did not rise with gestation, whereas maternal CRH levels did (r = 0.58; n = 36; p < 0.0001). There was a modest correlation between paired maternal and fetal values (r = 0.36; n = 36; p = 0.03).

CONCLUSIONS

Acute fetal stress, caused by IHV needling of the fetal abdomen, resulted in hypothalamic-pituitary-adrenal axis activation, as shown by a rise in fetal cortisol and corticotrophin. However, it did not result in measurable CRH release into fetal plasma. This suggests that fetal plasma CRH is not derived from the hypophyseal-portal circulation, but from another source, presumably the placenta.

The effects of intramuscular administration of corticosteroids on the induction of parturition

Our purpose was to examine the hypothesis that corticosteroids, when administered intramuscularly, can enhance the labor process and reduce the time interval between the induction and the active phase. A randomized, controlled study was conducted on 66 women with gestational age of 41 weeks and over and favorable cervix (bishop score > or = 7). The study group (n = 32) received 10 mg of dexamethasone phosphate intramuscularly in two doses at an interval of 12 hours, and the day after the enrolling administration intravenous oxytocin was given. The control group (n = 33) received only intravenous oxytocin 24 hours after enrolling. The number of patients to enter the active phase of labor was significantly higher in the study group than in the control group (n = 33 [100%] vs n = 29 [87.9%], p < 0.039). The mean time interval between induction of labor and the active phase was significantly shorter in the study group than in the control group (1.7 +/- 1.5 hours vs 4 +/- 1.7, P < 0.0001), and the mean of oxytocin dose was significantly lower in the study group (1.15 +/- 1.5 u vs 4.16 +/- 2.5 u, P < 0.0001). Induction of labor with the use of intramuscularly injected dexamethasone phosphate reduced the time interval between the induction of labor and the active phase.

The hypothalamic pituitary axis in the fetus and newborn

Glucocorticoid receptor activation in the fetal lung triggers maturation necessary for extra-uterine life. Antenatal treatment with betamethasone and dexamethasone has lowered severity of respiratory distress in very low birth weight infants, and dexamethasone given postnatally has resulted in short-term improvement in chronic lung disease. Recently, however, surfactant therapy has diminished the differential benefit of antenatal glucocorticoid treatment, and it has been difficult to show that postnatal dexamethasone therapy improves survival. Treated infants may have reduced weight gain, adrenal suppression, increased incidence of intestinal perforation and infection, and long-term developmental and metabolic problems. Recent data suggest that the fetal hypothalamic/pituitary/adrenal axis is active early and is precisely structured for an intricate sequence of specifically fetal developmental events, which may be deranged by dexamethasone therapy. We consider data suggesting that persistence of the fetal pattern in some premature infants constitutes adrenal insufficiency, and that therapy at stress replacement doses with less potent glucocorticoids might avoid side effects seen with traditional regimens.

Glucocorticoid regulation of human and ovine parturition: the relationship between fetal hypothalamic-pituitary-adrenal axis activation and intrauterine prostaglandin production

Birth in many animal species and in humans is associated with activation of hypothalamic-pituitary-adrenal function in the fetus and the increased influence of glucocorticoids on trophoblast cells of the placenta and fetal membranes. We suggest that in ovine pregnancy glucocorticoids directly increase fetal placental prostaglandin production, and indirectly increase prostaglandin production by maternal uterine tissues through the stimulation of placental estradiol synthesis. The events of ovine parturition are compared with those of human parturition. In the latter, we suggest similar direct effects of glucocorticoids on prostaglandin synthesis and metabolism in fetal membranes and similar indirect effects mediated by glucocorticoid-stimulated increases in intrauterine corticotropin-releasing hormone expression.

The role of corticotropin-releasing hormone receptors in placenta and fetal membranes during human pregnancy

Corticotropin-releasing hormone (CRH) is a 41 amino acid polypeptide that exerts a wide spectrum of hypothalamic and extrahypothalamic functions. Moreover, the placenta and other intrauterine tissues produce and secrete immunoreactive CRH. It has been demonstrated that placental CRH is secreted into the maternal circulation in large amounts during the third trimester of human pregnancy and may play an important role in the onset of labor. CRH exerts a number of functions within the intratuterine environment like induction of prostaglandin production and maintenance of the placental blood flow. Here we present an overview of current knowledge about the CRH receptor subtypes and their signaling properties within the feto-placental unit.

Localization and characterization of urocortin during human pregnancy

Urocortin, a recently identified peptide of the corticotropin releasing hormone (CRH) peptide family, has potent vasodilatory effects in the human fetal placental circulation in vitro, promoting us to hypothesize that urocortin is produced locally to regulate uteroplacental vascular tone during pregnancy. In the present study, we examined the distribution of urocortin in the human placenta, fetal membranes and uterine tissue at term in the presence and absence of labour, using a urocortin antibody produced in our laboratory and the immunoperoxidase staining method. Immunoreactive (IR)-urocortin was observed in the vascular smooth muscle of the myometrium (n=5), decidual stromal cells, syncytiotrophoblast and amnion epithelium (n=10). No differences in staining intensity for urocortin were detected between tissues obtained in the absence (n=5) or presence (n=5) of labour. Staining intensity for IR-urocortin was greatest in the decidua suggesting this may be a site of urocortin production during pregnancy. Subsequently, we tested urocortin secretion from chorio-decidual cells in vitro, using an immunoblot technique. Positive staining for urocortin was observed in 40 per cent of chorio-decidual cells with 34 per cent of these cells secreting urocortin under basal conditions. Since urocortin was secreted by decidual cells we questioned whether urocortin was present in maternal plasma throughout gestation, using radioimmunoassay. Urocortin was detectable in maternal plasma from 7 weeks of gestation and concentrations did not change as gestation progressed. IR-urocortin in the maternal plasma eluted from a Sephadex G-50 column at the same site as synthetic urocortin and had a calculated retention coefficient (Kd) of 0.44. In summary, this study indicates that urocortin is produced by the decidua during human pregnancy and is detectable in maternal plasma. These data are consistent with the hypothesis that urocortin is produced locally by the decidua and may act to regulate uteroplacental blood flow.

Endocrine and paracrine regulation of birth at term and preterm

We have examined factors concerned with the maintenance of uterine quiescence during pregnancy and the onset of uterine activity at term in an animal model, the sheep, and in primate species. We suggest that in both species the fetus exerts a critical role in the processes leading to birth, and that activation of the fetal hypothalamic-pituitary-adrenal axis is a central mechanism by which the fetal influence on gestation length is exerted. Increased cortisol output from the fetal adrenal gland is a common characteristic across animal species. In primates, there is, in addition, increased output of estrogen precursor from the adrenal in late gestation. The end result, however, in primates and in sheep is similar: an increase in estrogen production from the placenta and intrauterine tissues. We have revised the pathway by which endocrine events associated with parturition in the sheep come about and suggest that fetal cortisol directly affects placental PGHS expression. In human pregnancy we suggest that cortisol increases PGHS expression, activity, and PG output in human fetal membranes in a similar manner. Simultaneously, cortisol contributes to decreases in PG metabolism and to a feed-forward loop involving elevation of CRH production from intrauterine tissues. In human pregnancy, there is no systemic withdrawal of progesterone in late gestation. We have argued that high circulating progesterone concentrations are required to effect regionalization of uterine activity, with predominantly relaxation in the lower uterine segment, allowing contractions in the fundal region to precipitate delivery. This new information, arising from basic and clinical studies, should further the development of new methods of diagnosing the patient at risk of preterm labor, and the use of scientifically based strategies specifically for the management of this condition, which will improve the health of the newborn.

Activation of L-type calcium channels induces corticotropin-releasing factor secretion from human placental trophoblasts

The ultimate outcome of pregnancy, parturition, is a well orchestrated process in which placental corticotropin-releasing factor (CRF) seems to play an important role. The objective of the present study was to investigate the involvement of L-type calcium channels and calcium-dependent signaling in the depolarization-induced CRF release from human syncytiotrophoblast. The basal secretion of CRF by trophoblastic cells, isolated from human term placenta, was maximal after their functional differentiation, which was monitored by hCG measurements. On the fourth day of culture, the basal CRF secretion of the cells in serum-free medium was linear between 2 and 8 h. Incubation of the trophoblasts with KCl, a depolarizing stimulus, or with Bay K8644, an L-type calcium channel agonist, for 3 or 8 h led to an increase in CRF secretion, but was without effect on its synthesis. This stimulated CRF release was calcium dependent, as it could be prevented by loading cells with 1,2-bis(0-Aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (acetoxymethyl) ester. Furthermore, the KCl-induced CRF secretion involved L-type calcium channels activation, as 2 micromol/L nitrendipine, an L-type specific blocker, abolished the stimulation. In trophoblasts, where we have previously shown calcium-dependent protein kinase C (cPKCs) activity, incubation with Bay K8644 also stimulated calcium calmodulin kinase II (CaMKII) and extracellular regulated kinase activities. In the present study we observed that CaMKII and cPKCs were linked to the Bay K8644-induced secretion of CRF, as only the autocamtide-2 related inhibitory peptide, a CaMKII inhibitor, and Gö6976, an inhibitor of mu and cPKCs partially prevented (30-78%) the activation of CRF release by Bay K8644. The use of PD 098056, an inhibitor of the ERKs kinases, showed no effect on CRF release. Taken together, these results support a depolarization-induced and calcium-dependent exocytotic-like secretion of CRF from human placental trophoblasts. In addition, CaMKII and cPKCs seem to be potential modulators or mediators of these calcium effects on CRF secretion.

Corticotropin-releasing hormone, corticotropin-releasing hormone-binding protein, and activin A in maternal serum: prediction of preterm delivery and response to glucocorticoids in women with symptoms of preterm labor

OBJECTIVE

The aim of this study was to determine prospectively whether serum concentrations of corticotropin-releasing hormone, corticotropin-releasing hormone-binding protein, and activin A (1) predict preterm birth within 10 days of hospital admission or at <37 weeks' gestation among women with symptoms of preterm labor and (2) are affected by glucocorticoid therapy.

STUDY DESIGN

Serum concentrations of corticotropin-releasing hormone and activin A were measured in 94 women with symptoms of preterm labor between 24 and 34 weeks' gestation, and delivery outcomes were monitored. Corticotropin-releasing hormone-binding protein concentrations were measured in 71 of these women. In a subgroup of 15 women the serum analytes were assayed in conjunction with estriol before and 12 to 24 hours after administration of dexamethasone.

RESULTS

Forty-six percent (6/13) of the women who were delivered within 10 days of hospital admission had a raised serum corticotropin-releasing hormone level, but the predictive relationship was not significant (chi(2) = 1.7; P =.2). Among the 31 women (including the 6 previously mentioned) who were delivered at <37 weeks' gestation, 39% (12/31) had a raised corticotropin-releasing hormone level. Although a raised corticotropin-releasing hormone concentration was positively associated with delivery at <37 weeks' gestation (chi(2) = 9; P =.003), the predictive diagnostic value was poor, with sensitivity, specificity, and positive and negative predictive values of 39%, 90%, 67%, and 75%, respectively. The serum concentrations of corticotropin-releasing hormone-binding protein and activin A were unrelated to gestational age at delivery. Dexamethasone markedly lowered the serum estriol level (P <.001) but had no effect on concentrations of corticotropinreleasing hormone, corticotropin-releasing hormone-binding protein, and activin A.

CONCLUSION

Serum concentrations of corticotropin-releasing hormone, corticotropin-releasing hormone-binding protein, and activin A are not clinically useful for the prediction of preterm delivery among women with symptoms of preterm labor and are not affected by administration of glucocorticoids.

Characterization of neuropeptide Y-mediated corticotropin-releasing factor synthesis and release from human placental trophoblasts

Neuropeptide Y (NPY) is a CRF secretagogue for human placental cells in culture. We have studied the involvement of intracellular calcium and calcium-dependent signaling in the NPY-induced CRF release in trophoblastic cells. The incubation of trophoblasts with NPY for 3 and 8 h led to a dose-dependent increase in CRF secretion. Also, NPY stimulated synthesis of this peptide hormone upon an 8-h incubation period. BIBP3226, a selective Y1 receptor antagonist, and pertussis toxin (PTX) eliminated these effects. NPY-stimulated CRF secretion was mostly prevented by loading cells with BAPTA-AM, suggesting that elevation of intracellular calcium is responsible for the increase of CRF secretion. However, this calcium chelator had no effect on CRF synthesis. Furthermore, U-73122, a phospholipase C-betas (PLC) inhibitor or xestospongin C, an inositol triphosphate receptor (InsP3-R) blocker, have partially prevented the effect of NPY on CRF synthesis and secretion. Therefore, the increase in CRF synthesis and secretion rely in part on the release of calcium from intracellular store. Interestingly, SKF 96365, an inhibitor of store operated calcium (SOC) influx, also partially blocked the NPY stimulatory effect on CRF release but not its synthesis, suggesting that calcium influx is also involved in this stimulation. In the syncytiotrophoblast, known to possess a NPY-activated protein kinase C (PKCs) activity, NPY also stimulated calcium calmodulin kinase II (CaMKII) and extracellular regulated kinase (ERK1/2) activities. In the present study, we observed that bisindolylmaleimide (BIM), a nonspecific PKCs inhibitor partially prevented the NPY-induced CRF release. On the other hand, autocamtide-2 related inhibitory peptide (AIP), a CaMKII inhibitor, prevented most of the stimulatory effect of NPY on both CRF synthesis and release. Go6976, an inhibitor of the conventional and mu PKCs and PD 098059, an inhibitor of the ERK cascade, had no effect on neither CRF synthesis nor release. Altogether, these results support a Y1 receptor-mediated PTX-sensitive induction on CRF synthesis and release by NPY from human placental trophoblasts. The stimulation of CRF synthesis by NPY seems to depend mainly on a PLC-beta to InsP3-R axis and on CaMKII activity. Also, the release of CRF depends on the PLC-beta to InsP3-R axis and CaMKII activity but also entails the participation of a calcium-independent PKCs.

Maternal hypothalamic-pituitary-adrenal axis in pregnancy and the postpartum period. Postpartum-related disorders

During pregnancy, placenta-derived CRH increases exponentially in the plasma. Circulating levels of CRH-binding protein decrease considerably in the last trimester of pregnancy, resulting in further elevation of bioavailable plasma CRH. The adrenal glands during pregnancy gradually become hypertrophic because of the increase in ACTH, which parallels that of CRH. Thus, pregnancy is a transient period of relative hypercortisolism. The activation of the hypothalamic-pituitary-adrenal axis during pregnancy has been proposed to function as a biological clock. In this model, the placenta is perceived as a stress-sensitive organ and placental CRH as a timing starter, determining a preterm, term, or postterm labor. During pregnancy, as well as during the immediate postpartum period, the hypothalamic maternal CRH secretion is suppressed, because of the circulating levels of cortisol. Hypothalamic CRH secretion normalizes within 12 weeks. This transient postpartum maternal hypothalamic CRH suppression, together with the steroid withdrawal that follows parturition, might be causally related to the mood disorders and the vulnerability to autoimmune diseases such as thyroiditis or rheumatoid arthritis often observed during the postpartum period.

Intrauterine infection and preterm delivery: evidence for activation of the fetal hypothalamic-pituitary-adrenal axis

OBJECTIVE

We studied pregnant women in preterm labor with and without intrauterine infection to determine whether fetal hypothalamic-pituitary-adrenal axis activation occurs in the setting of infection-induced preterm parturition.

STUDY DESIGN

Amniotic fluid collected by amniocentesis and maternal blood from patients in preterm labor with intact membranes at 24 to 34 weeks' gestation were analyzed by radioimmunoassay for the steroid hormones estrone, estradiol, progesterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and cortisol. Amniotic fluid was also obtained for microbial culture and for interleukin 6 measurements by enzyme immunoassay.

RESULTS

Patients with intrauterine infection (n = 11) had significantly higher amniotic fluid concentrations of dehydroepiandrosterone (539 +/- 79 pg/mL) and of cortisol (5.28 +/- 1.0 microg/dL) than did patients with preterm labor and preterm delivery without infection (n = 11; 273 +/- 82 pg/mL and 1.61 +/- 1.05 microg/dL, respectively) or patients with preterm labor and subsequent term delivery (n = 11; 202 +/- 79 pg/mL and 1.82 +/- 1.0 microg/dL, respectively). Furthermore those patients who were delivered within 7 days after enrollment (who were also more likely to have intrauterine infection) had higher amniotic fluid concentrations than did those who were not delivered within 7 days of both estrone (586 +/- 101 pg/mL vs 314 +/- 98 pg/mL) and estradiol (238 +/- 44 pg/mL vs 91 +/- 43 pg/mL).

CONCLUSION

Intrauterine infection was associated with increased fetal adrenal androgen and cortisol biosynthesis, and delivery within 7 days after the onset of preterm labor was associated with increased placental estrogen synthesis. These data are consistent with fetal hypothalamic-pituitary-adrenal axis activation in the setting of infection-associated preterm delivery.

Short- and long-term consequences of corticotropin-releasing factor in early development

Corticotropin-releasing factor (CRF) mediates various stress-related responses in adult animals. Little is known about the effects of CRF during early development. Young mammals often vocalize when isolated in novel surroundings. Heightened levels of CRF inhibit vocalizing in isolated rat and guinea pig pups. Still lower levels of CRF may facilitate or permit vocalizing in rat pups. In guinea pigs, CRF appears to move pups from an initial active, to a subsequent passive, stage of behavioral responsiveness. CRF activity prior to birth can also affect the young. Exposing pregnant female rats to stressors during the last trimester of pregnancy alters the morphological and behavioral development of the offspring. Effects of gestational stress can be mimicked by injecting pregnant females with CRF during the last trimester. CRF appears to mediate both short- and long-term responses to stressors during developmental in rodents.

Prenatal dexamethasone treatment does not prevent alterations of the hypothalamic pituitary adrenal axis in steroid 21-hydroxylase deficient mice

A major difficulty in the clinical management of congenital adrenal hyperplasia (CAH) is adjustment of glucocorticoid doses to suppress ACTH and androgens without causing iatrogenic hypercortisolism. The possibility that structural alterations of the adrenal or a dysfunction of the hypothalamic pituitary adrenal (HPA) axis caused by glucocorticoid deficiency during fetal life contribute to this problem was studied in 21-hydroxylase deficient mice caused by deletion of the cytochrome P-450 21-hydroxylase gene. Homozygotes showed about 200-fold elevations in plasma progesterone, hyperplastic adrenal cortices lacking zonation, and structural alterations of adrenocortical mitochondria. Histochemical studies showed increases in hypothalamic CRH messenger RNA (mRNA) and immunoreactive (ir) CRH, and pituitary POMC mRNA in homozygous mice. VP mRNA levels in PVN perikarya were normal, but irVP in parvicellular terminals of the median eminence was increased in homozygotes. Prenatal dexamethasone treatment (0.5 to 2 microg/day) prevented the increases in CRH mRNA, whereas dexamethasone only partially decreased POMC mRNA levels, and had no effect on serum progesterone levels. The data suggest that intrauterine glucocorticoid deficiency in CAH causes hyperactivity of the hypothalamic-pituitary-corticotroph axis and insensitivity to glucocorticoid feedback. These studies in 21-hydroxylase deficient mice may provide new insights on the mechanism, clinical manifestations and management of some types of human CAH.

Endometrial corticotropin-releasing hormone. Its potential autocrine and paracrine actions

Corticotropin-releasing hormone (CRH) is expressed at several peripheral tissues including normal epithelial cells of human and rodent uterus. However, its biological role is unknown in both species. To clarify this role we studied the regulation of CRH promoter in endometrial cells. We performed homologous transfection experiments in Ishikawa cells, a human endometrial cell line, using a 0.9-kb fragment of the 5'-flanking region of human CRH gene coupled to luciferase. We found that the activity of the 5'-flanking region of the CRH gene is stimulated by cAMP and EGF and inhibited in a receptor-mediated, dose-dependent fashion by estradiol and dexamethasone. The antiglucocorticoid RU 486 acted as a glucocorticoid agonist suppressing CRH gene activation, whereas progesterone was devoid of any activity. Prostaglandin E2 and interleukins-1 and -6 stimulated CRH activation, and the prostanoid inhibitor indomethacin suppressed it, most probably by inhibiting endogenous prostaglandins. These findings suggest that endometrial CRH gene expression may be under the negative control of estrogens and glucocorticoids and under the positive control of PGE2, IL-1, and IL-6. Considering the involvement of CRH in proinflammatory phenomena, we postulate that endometrial CRH, in association with uterine prostanoids and cytokines, may participate in intrauterine inflammatory processes of early pregnancy, such as decidualization and blastocyst implantation.

The effect of dexamethasone on CRH and prostanoid production from human term placenta

The human placenta at term produces large quantities of corticotropin releasing hormone (CRH) and prostanoids. These hormones play an important role in the maintenance of pregnancy, and the initiation and progress of labor; yet little is known of factors affecting their regulation and the interrelationship of CRH and prostanoid production. In these studies we have investigated the effect of dexamethasone on the production of CRH and prostanoids from fresh human term placental tissues. The basal release of prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), thromboxane B2 (TxB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) from human term placental explants increased from the fifth hour in culture, while the release of 13,14-dihydro-15-keto-PGF2 alpha (PGFM) was not significantly changed during this period. The addition of dexamethasone (10(-8) M) to the perifusing medium resulted in a rapid and dramatic inhibition of PGE2, PGF2 alpha, PGFM, TxB2 and 6-keto-PGF1 alpha release. On the other hand, CRH release was not significantly changed throughout the seven hours of incubation with dexamethasone. These data demonstrate that glucocorticoids at physiologic concentrations can inhibit human term placental prostanoid production, and thus glucocorticoid production may play an important role in the physiological regulation of placental prostanoid production in the human placenta. However, dexamethasone did not alter CRH release, demonstrating that the inhibition of placental prostanoids by dexamethasone is not a CRH mediated event.

Current topic: the placental corticotrophin-releasing hormone-adrenocorticotrophin axis

In this review the factors regulating production of corticotrophin-releasing hormone (CRH) in intrauterine tissues are discussed and interactions of placental CRH with placental pro-opiomelanocortin (POMC)/adrenocorticotrophin (ACTH) and prostaglandins (PG) are examined. Discrepant results concerning localization of immunoreactive (IR-) CRH and its binding protein (CRH-BP) and their mRNAs in intrauterine tissues are described, and these issues require further resolution. It is suggested that the CRH-ACTH-PG axis in the placenta and choriodecidua may be important in relation to paracrine/autocrine regulation of uteroplacental blood flow, and in term and preterm labour. During the initial stages of preterm labour in the setting of infection, intrauterine cytokines and other factors may stimulate CRH output, implying a role for the immune-neuroendocrine axes in this process. With loss of chronic trophoblasts in advanced infection leading to preterm labour, a major intrauterine site of CRH production may be lost and the influence of this pathway becomes minimal. At this time increased intrauterine prostaglandin synthesis, together with loss of prostaglandin dehydrogenase activity in the fetal membranes, may become the primary route leading to myometrial activity and delivery.

Corticotropin releasing factor decidualizes human endometrial stromal cells in vitro. Interaction with progestin

Decidualization of endometrial cells is a hormone-dependent process of differentiation which occurs during the menstrual cycle and pregnancy. Recent in vitro studies have revealed that cAMP and its generators induce decidualization of stromal cells isolated from proliferative endometrium and that progestins enhance the effect of cAMP. Since corticotropin releasing factor (CRF) generates cAMP and prostaglandins in other organs, in the present study the effect of CRF, a hypothalamic factor also produced by decidua and fetal membranes, on in vitro decidualization of endometrial stromal cells was evaluated. The addition of CRF to a culture medium of stromal cells induced in vitro decidualization, as indicated by morphologic changes from elongated fibroblast-like cells into larger and round cells and by the release of prolactin in the medium. The effect of CRF on stromal cells and on prolactin release was significantly augmented by the coincubation in the presence of medroxyprogesterone acetate. This observation indicates CRF as a novel factor of decidualization and confirms that progestins act as enhancers of the expression of decidual products.

Negative regulation of placental fibronectin expression by glucocorticoids and cyclic adenosine 3',5'-monophosphate

Fibronectin is a ubiquitous extracellular matrix (ECM) protein known to play a critical role in cell adhesion. In the present study we dissected the effects of glucocorticoids and cyclic adenosine 3',5'-monophosphate (cAMP) on FN expression in cultures of cytotrophoblasts isolated from human term placentas to identify compounds which may influence uterine-placental adherence. Based on immunoassay data, relative to controls, glucocorticoid treatment (1-1000 nM) of cytotrophoblasts specifically inhibited media levels of oncofetal FN (i.e., FNs bearing an oncofetal epitope) 65-92%. Treatment of cytotrophoblasts with androgens, estrogens, and progestins (1-1000 nM) did not markedly affect onfFN expression. Corticotropin-releasing hormone (CRH) treatment (200 nM) alone had no effect on levels on onfFN. In combination experiments using 100 nM dexamethasone (DEX), 1000 nM medroxyprogesterone acetate (MPA), 10 nM estradiol (E2) and 200 nM corticotropin-releasing hormone CRH, we observed that DEX treatment also promoted approximately an 85% reduction in media levels of onfFN. This indicated that glucocorticoids profoundly suppress FN expression in the presence of high concentrations of other steroids and pregnancy-associated paracrine effectors. To examine the influence of ECM protein composition on glucocorticoid-mediated suppression of onfFN expression, cells were inoculated on untreated culture wells or on wells coated with FN, laminin, or collagen I. We observed that DEX treatment downregulated onfFN levels 70-85% under each of these conditions, suggesting that glucocorticoid effects on FN expression were not dependent on the presence of an exogenous ECM. Treatment of cytotrophoblasts with 8-bromo-cAMP resulted in a dose-dependent reduction in onfFN expression to 3% of control levels with an EC50 of 150 nM. Based on Northern blotting, treatment of cytotrophoblasts with 100 nM DEX, 1 mM 8-bromo-cAMP, or 2 nM relaxin inhibited steady state levels of FN mRNA approximately 90% relative to controls. Our results suggest that during pregnancy glucocorticoids and compounds that alter intracellular concentrations of cAMP may profoundly suppress FN expression and therefore may have dramatic effects on uterine-placental adherence.

Corticotropin-releasing hormone increases prostaglandin F2 alpha activity on human myometrium in vitro

OBJECTIVE

Our purpose was to study the capability of synthetic corticotropin-releasing hormone to directly stimulate human myometrium and to modulate the activity of prostaglandins F2 alpha and E2.

STUDY DESIGN

Strips from human myometrium were obtained from 127 elective cesarean sections at term. The in vitro effect of human rat corticotropin-releasing hormone on myometrial contractility has been studied in resting myometrial strips mounted in a two-chamber bath for isolated organs. Stimuli (corticotropin-releasing hormone, prostaglandins F2 alpha and E2, and oxytocin) were administered as one single dose in the perfusion chamber. In each experiment one myometrial strip was used as a control.

RESULTS

Corticotropin-releasing hormone significantly increases (p < 0.01) the myometrial response to prostaglandin F2 alpha. The hormone neither has a direct inotropic effect nor is it able to enhance the effect of prostaglandin E2 and oxytocin on myometrial strips.

CONCLUSION

The positive effect of corticotropin-releasing hormone on the myometrial response to prostaglandin F2 alpha adds new support to the theory that placental corticotropins may modulate the onset of labor.

Effects of the synthetic glucocorticoid triamcinolone acetonide on vasoactive hydrolases of the human placenta in vitro

Therapy with glucocorticoids during pregnancy is still debated. Previously reported effects of glucocorticoid application in rats resemble certain symptoms of preeclampsia. Therefore, we studied in vitro the effects of the synthetic glucocorticoid triamcinolone acetonide soluble (0.1-10 mM) on placental alpha-glutamyl amino-peptidase, microsomal alanyl aminopeptidase, dipeptidyl peptidase IV, acetylcholinesterase and butyrylcholinesterase in purified trophoblast monolayers and villous explants from first trimester (n = 5) and term placentae (n = 9) using bio- and histochemical methods. In term placentae quantitative histochemistry (microdensitometry) of trophoblast monolayers revealed an increase of alpha-glutamyl aminopeptidase and microsomal alanyl aminopeptidase activity up to 149% and 126% respectively, after treatment with supraphysiological doses. In trophoblast monolayers from first trimester alpha-glutamyl aminopeptidase activity was not affected, whereas microsomal alanyl aminopeptidase activity increased by 25%. Dipeptidyl peptidase IV staining was reduced to 26%. Biochemical measurements of alpha-glutamyl aminopeptidase and microsomal alanyl aminopeptidase activity in homogenates of cultured villi revealed effects similar to those found by microdensitometry in trophoblast monolayers. In contrast, dipeptidyl peptidase IV activity increased in explants of term placentae by 47%. Acetyl- and butyrylcholinesterase activities were reduced in term placental villi by 38% and 40%, respectively. The data indicate that glucocorticoids may affect the activity of hydrolases which are thought to be involved in local placental blood pressure modulation.

Tentativeness and fervor in cell biology require negative and positive feedforward control

End-product feedback regulates early steps in metabolic pathways, affecting activation and the rate of end-product synthesis. Early formation of end-product also modifies later steps in the synthesis of end-product. We designate this form of regulation feedforward. Negative feedback/feedforward by end-products may result in homeostasis, but also in physiologic tentativeness. Positive feedback/feedforward by end-product gives rise to fervid events. Tentativeness and fervor, due to negative and positive feedforward rather than feedback, explain otherwise puzzling aspects of immunology and endocrinology.