Antenatal Glucocorticoid Exposure Research Articles

Gestational Exposure to Maternal Systemic Glucocorticoids and Childhood Risk of CKD

Background & ObjectivesThe potential effects of antenatal glucocorticoid exposure on the health of children are unclear. We examined the association of gestational exposure to maternal systemic glucocorticoids (SG) and the risk of developing chronic kidney disease (CKD) in childhood. Study designRetrospective cohort study. Setting & ParticipantsNewborns cared for at the largest healthcare delivery system in Taiwan between 2004 and 2018. ExposureMaternal prescriptions for SG between the last menstrual period and birth as a proxy for gestational exposure. OutcomeIncidence of childhood CKD, including congenital anomalies of the kidney and urinary tract (CAKUT) and other kidney diseases (non-CAKUT) over 10 years. Analytical ApproachCox proportional hazards models with stabilized inverse probability of treatment weighting and robust sandwich estimator were used to estimate the average association between SG and incident CKD after adjustment for offspring characteristics (aHR). ResultsAmong 23,363 singleton-born children, gestational SG exposure was significantly associated with a higher risk of childhood CKD (aHR, 1.69 [95% CI, 1.01–2.84]). Stratified analyses showed stronger associations between SG and childhood CKD within the strata of birth <37 weeks gestational age (aHR, 2.38 [95% CI, 1.19–4.78]), male sex (aHR, 1.89 [95% CI, 1.00–3.55]), gestational exposure in the second trimester (aHR, 6.70 [95% CI, 2.17–20.64]), and total dose >24 mg hydrocortisone equivalent (aHR, 1.91 [95% CI, 1.05–3.47). LimitationsStudy was limited to the Taiwan healthcare delivery system and childhood CKD events through age 10 years. ConclusionsThe findings of this study suggest that gestational exposure to systemic glucocorticoids is associated with the occurrence of kidney disease in childhood. If these findings are confirmed, they may inform clinicians who are considering prescribing SG during pregnancy.

Antenatal Dexamethasone Exposure Impairs Vascular Contractile Functions via Upregulating IP3 Receptor 1 and Cav1.2 in Adult Male Offspring.

Administration of antenatal glucocorticoids remains common practice for treating preterm delivery. Antenatal glucocorticoid exposure increased the risk of developing vascular diseases in later life, but the precise mechanisms remain unclear. This study aimed to explore the effects and mechanisms of antenatal exposure to clinically relevant doses of dexamethasone (synthetic glucocorticoids) on vascular functions in adult male offspring. Pregnant Sprague-Dawley rats received dexamethasone or vehicle during the last week of pregnancy. Male offspring were killed at gestational day 21 (Fetus) or postnatal day 120 (adult offspring). Mesenteric arteries were collected for vascular function, electrophysiology, target gene expression, and promotor methylation studies. Antenatal dexamethasone exposure increased phenylephrine-mediated vascular contractility in offspring, which was resulted by the activated inositol 1,4,5-trisphosphate (IP3) receptor and L-type Ca2+ channels. Specifically, increases of IP3R1 (IP3 receptor 1) and Cav1.2 (L-type Ca2+ channels subunit alpha1 C) were responsible for an activated IP3-Ca2+ pathway in the vasculature, and eventually predisposed the antenatal dexamethasone offspring to vascular hypercontractility. In addition, IP3R1 and Cav1.2 was upregulated through transcriptional mechanism; the overall changes in promotor histone modifications were consistent with the corresponding changes in transcriptional levels of the 2 genes, suggesting that antenatal dexamethasone exposure activated the transcription of IP3R1 and Cav1.2 via altering promotor histone modifications. Taken together, this study demonstrated that antenatal dexamethasone exposure resulted in vascular adverse outcomes in male offspring that is linked to the increases of IP3R1 and Cav1.2 mediated by epigenetic modifications in the vasculature.

Association between antenatal glucocorticoid exposure and the activity of the stress system, cognition, and behavior in 8- to 9-year-old children: A prospective observational study.

Glucocorticoid (GC) -induced fetal programming of the activity of the hypothalamus-pituitary-adrenal axis (HPAA) and its associated cognitive and behavioral consequences in later life have been well characterized in several animal species. However, information on humans is scarce. In this study, we examined HPAA activity markers and associated outcomes at 8 to 9 years of age among children prenatally exposed to GC for suspected preterm birth. Our hypothesis was that antenatal exposure to the betamethasone (BM) is associated with exacerbation of HPAA activity in childhood. Prospective observational study in 31 children whose mothers received single (n=19) or multiple (n=12) courses of BM for threatened preterm birth but born with normal weight appropriate for the gestational age (median 37+6 weeks of gestation) compared with 38 non-exposed, age-matched children. Primary end point was the activity of the HPAA in response to the Trier Social Stress Test. Secondary end points were changes in autonomic nervous system (ANS) activity, cognitive performance (IQ), attention-deficit/hyperactivity disorder (ADHD) symptoms, and electrocortical activity (EEG). There was no statistically significant difference in HPAA activity markers between antenatal BM exposed and unexposed groups. ANS activity in BM-exposed children shifted towards a higher parasympathetic tone reflected by a higher overall high-frequency band power of heart rate variability. IQ scores were within normal limits for both groups; however, BM-exposed children had lower IQ scores than the unexposed group. BM-exposed group had marginally more ADHD core symptoms and increased electrocortical activity in the occipital brain region compared with controls. A monotonic dose-response relation between BM exposure and activity of the ANS and IQ was estimated in post-hoc analyses. Antenatal exposure to BM in the context of threatened preterm birth was not associated with changes in HPAA activity in childhood. However, BM exposure may be associated with changes in ANS activity. Antenatal GC prophylaxis is a valuable and often life-saving therapy, but its prescription may warrant a well-balanced risk-benefit assessment.

FC039: Associations between Maternal Antenatal Systemic Glucocorticoids Usage and Childhood Chronic Kidney Disease

Abstract BACKGROUND AND AIMS The effect of antenatal glucocorticoid exposure on offspring health is currently unclear. Therefore, this study examined the association of maternal exposure to systemic glucocorticoids in the past and during pregnancy with the risk of chronic kidney disease (CKD) development in childhood. Methods A retrospective cohort study of maternal-child dyads was identified from the largest healthcare delivery system in Taiwan between 1 January 2004 and 31 December 2018. Primary analyses were used to compare past and gestational exposures with non-exposure to systemic glucocorticoid considering an inverse probability of treatment weight to adjust the hazard ratio of offspring CKD development in singleton child-matched pairs. Offspring birthweight, sex, gestational weeks stratified analyses and sibling-matched sensitivity analyses were performed to ensure the robustness of the primary study results. RESULTS In a cohort with 31 927 singleton born children, the cumulative incidence of CKD was 2.23% (n = 713), with 3.18% (n = 63) in the gestational glucocorticoid-exposed group, 1.91% (n = 58) in the past exposed group and 2.2% (n = 592) in the non-exposed group. Gestational exposure, compared with non-exposure, was significantly associated with a higher risk of childhood CKD (inverse probability therapeutic weighted hazard ratio [wHR], 1.42 [95% confidence interval (95% CI) 1.05–1.92] in Figure. 1A, but not past exposure (wHR: 0.89, 95% CI 0.67–1.18) (Figure. 1B). In male children, the risk of CKD was significantly higher among gestational-exposed children than among unexposed children (wHR: 1.72, 95% CI 1.21–2.43). The cohort with sibling matched children did not show a significantly increased risk of childhood CKD associated with gestational exposure (wHR: 1.31, 95% CI 0.79–2.18) (Figure. 1A). CONCLUSION Maternal gestational glucocorticoid treatment was found to be significantly associated with CKD development in children. These findings may support clinicians in performing benefit-risk assessment and in decision-making for systemic glucocorticoid treatment during pregnancy, in clinical settings.

No long-term effects of antenatal synthetic glucocorticoid exposure on epigenetic regulation of stress-related genes

Antenatal synthetic glucocorticoid (sGC) treatment is a potent modifier of the hypothalamic-pituitary-adrenal (HPA) axis. In this context, epigenetic modifications are discussed as potential regulators explaining how prenatal exposure to GCs might translate into persistent changes of HPA axis “functioning”. The purpose of this study was to investigate whether DNA methylation and gene expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) may mediate the persistent effects of sGC on cortisol stress reactivity that have been previously observed. In addition, hair cortisol concentrations (hairC) were investigated as a valid biomarker of long-term HPA axis activity. This cross-sectional study comprised 108 term-born children and adolescents, including individuals with antenatal GC treatment and controls. From whole blood, DNA methylation was analyzed by targeted deep bisulfite sequencing. Relative mRNA expression was determined by RT-qPCR experiments and qBase analysis. Acute stress reactivity was assessed by the Trier Social Stress Test (TSST) measuring salivary cortisol by ELISA and hairC concentrations were determined from hair samples by liquid chromatography coupled with tandem mass spectrometry. First, no differences in DNA methylation and mRNA expression levels of the stress-associated genes between individuals treated with antenatal sGC compared to controls were found. Second, DNA methylation and mRNA expression levels were neither associated with cortisol stress reactivity nor with hairC. These findings do not corroborate the belief that DNA methylation and mRNA expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) play a key mediating role of the persistent effects of sGC on HPA axis functioning.

The circadian phase of antenatal glucocorticoid treatment affects the risk of behavioral disorders

During pregnancy, maternal endocrine signals drive fetal development and program the offspring’s physiology. A disruption of maternal glucocorticoid (GC) homeostasis increases the child’s risk of developing psychiatric disorders later in life. We here show in mice, that the time of day of antenatal GC exposure predicts the behavioral phenotype of the adult offspring. Offspring of mothers receiving GCs out-of-phase compared to their endogenous circadian GC rhythm show elevated anxiety, impaired stress coping, and dysfunctional stress-axis regulation. The fetal circadian clock determines the vulnerability of the stress axis to GC treatment by controlling GC receptor (GR) availability in the hypothalamus. Similarly, a retrospective observational study indicates poorer stress compensatory capacity in 5-year old preterm infants whose mothers received antenatal GCs towards the evening. Our findings offer insights into the circadian physiology of feto-maternal crosstalk and assign a role to the fetal clock as a temporal gatekeeper of GC sensitivity.

No Association of Antenatal Synthetic Glucocorticoid Exposure and Hair Steroid Levels in Children and Adolescents.

Antenatal synthetic glucocorticoid (sGC) treatment constitutes a potent programming factor of the hypothalamic-pituitary-adrenal (HPA) axis. Previous findings from our group revealed long-term changes in cortisol stress reactivity following antenatal sGC therapy. However, the few prior studies exclusively relied on spot measurements of phasic HPA axis activity, which may not adequately capture cortisol output over prolonged periods of time. To address this gap, the current study utilized hair steroid concentrations, a valid marker of integrated long-term HPA-axis activity, to investigate endocrine changes in individuals treated with antenatal sGC. This cross-sectional study comprised 76 term-born children (7-12 years) and 58 adolescents (14-18 years). Cumulated hormonal secretion in scalp hair over a 3-month period was determined for different biomarkers of tonic HPA axis activity by liquid chromatography coupled with tandem mass spectrometry. Hair steroid levels were compared between participants with antenatal sGC therapy (dexamethasone or betamethasone) and different control groups. Findings from this study provide no evidence for a significant effect of antenatal sGCs on long-term hair steroid concentrations. Participants treated with antenatal sGC exhibited comparable levels of hair cortisol, cortisone, dehydroepiandrosterone, and cortisol/dehydroepiandrosterone ratios compared to those of mothers who had been admitted to hospital for pregnancy complications but had never received sGC therapy and controls from physiological pregnancies. In conjunction with data from previous studies, it is thus tempting to speculate that sGC may affect the capacity of dynamic changes and flexible adaption of an individual's HPA axis rather than changes in tonic steroid output.

Antenatal dexamethasone treatment transiently alters diastolic function in the mouse fetal heart.

Endogenous glucocorticoid action is important in the structural and functional maturation of the fetal heart. In fetal mice, although glucocorticoid concentrations are extremely low before E14.5, glucocorticoid receptor (GR) is expressed in the heart from E10.5. To investigate whether activation of cardiac GR prior to E14.5 induces precocious fetal heart maturation, we administered dexamethasone in the drinking water of pregnant dams from E12.5 to E15.5. To test the direct effects of glucocorticoids upon the cardiovascular system we used SMGRKO mice, with Sm22-Cre-mediated disruption of GR in cardiomyocytes and vascular smooth muscle. Contrary to expectations, echocardiography showed no advancement of functional maturation of the fetal heart. Moreover, litter size was decreased 2 days following cessation of antenatal glucocorticoid exposure, irrespective of fetal genotype. The myocardial performance index and E/A wave ratio, markers of fetal heart maturation, were not significantly affected by dexamethasone treatment in either genotype. Dexamethasone treatment transiently decreased the myocardial deceleration index (MDI; a marker of diastolic function), in control fetuses at E15.5, with recovery by E17.5, 2 days after cessation of treatment. MDI was lower in SMGRKO than in control fetuses and was unaffected by dexamethasone. The transient decrease in MDI was associated with repression of cardiac GR in control fetuses following dexamethasone treatment. Measurement of glucocorticoid levels in fetal tissue and hypothalamic corticotropin-releasing hormone (Crh) mRNA levels suggest complex and differential effects of dexamethasone treatment upon the hypothalamic–pituitary–adrenal axis between genotypes. These data suggest potentially detrimental and direct effects of antenatal glucocorticoid treatment upon fetal heart function.

Associations of antenatal glucocorticoid exposure with mental health in children.

Synthetic glucocorticoids, to enhance fetal maturation, are a standard treatment when preterm birth before 34 gestational weeks is imminent. While morbidity- and mortality-related benefits may outweigh potential neurodevelopmental harms in children born preterm (<37 gestational weeks), this may not hold true when pregnancy continues to term (⩾37 gestational weeks). We studied the association of antenatal betamethasone exposure on child mental health in preterm and term children. We included 4708 women and their children, born 2006-2010, from the Prediction and Prevention of Pre-eclampsia and Intrauterine Growth Restriction Study with information on both antenatal betamethasone treatment and child mental and behavioral disorders from the Finnish Hospital Discharge Register from the child's birth to 31 December 2016. Additional follow-up data on mother-reported psychiatric problems and developmental milestones were available for 2640 children at 3.5 (s.d. = 0.07) years-of-age. Of the children, 187 were born preterm (61 betamethasone-exposed) and 4521 at term (56 betamethasone-exposed). The prevalence of any mental and behavioral, psychological development, emotional and behavioral, and comorbid disorders was higher in the betamethasone-exposed, compared to non-exposed children [odds ratio 2.76 (95% confidence interval 1.76-4.32), 3.61 (2.19-5.95), 3.29 (1.86-5.82), and 6.04 (3.25-11.27), respectively]. Levels of psychiatric problems and prevalence of failure to meet the age-appropriate development in personal-social skills were also higher in mother-reports of betamethasone-exposed children. These associations did not vary significantly between preterm and term children. Antenatal betamethasone exposure may be associated with mental health problems in children born preterm and in those who end up being born at term.

Antenatal Glucocorticoid Exposure Results in Sex-Specific and Transgenerational Changes in Prefrontal Cortex Gene Transcription that Relate to Behavioural Outcomes

Synthetic glucocorticoids (sGC) are administered to women at risk for pre-term delivery to reduce respiratory distress syndrome in the newborn. The prefrontal cortex (PFC) is important in regulating stress responses and related behaviours and expresses high levels of glucocorticoid receptors (GR). Further, antenatal exposure to sGC results in a hyperactive phenotype in first generation (F1) juvenile male and female offspring, as well as F2 and F3 juvenile females from the paternal lineage. We hypothesized that multiple courses of antenatal sGC modify gene expression in the PFC, that these effects are sex-specific and maintained across multiple generations, and that the gene sets affected relate to modified locomotor activity. We performed RNA sequencing on PFC of F1 juvenile males and females, as well as F2 and F3 juvenile females from the paternal lineage and used regression modelling to relate gene expression and behavior. Antenatal sGC resulted in sex-specific and generation-specific changes in gene expression. Further, the expression of 4 genes (C9orf116, Calb1, Glra3, and Gpr52) explained 20–29% of the observed variability in locomotor activity. Antenatal exposure to sGC profoundly influences the developing PFC; effects are evident across multiple generations and may drive altered behavioural phenotypes.

Increased incidence of respiratory distress syndrome in neonates of mothers with abnormally invasive placentation.

BackgroundThe incidence of abnormally invasive placentation (AIP) is increasing. Most of these pregnancies are delivered preterm. We sought to characterize neonatal outcomes in AIP pregnancies.MethodsIn this retrospective case-control study (2006–2015), AIP neonates (n = 108) were matched to two controls each for gestational age, antenatal glucocorticoid exposure, sex, plurity, and delivery mode. Medical records were reviewed for neonatal and maternal characteristics/outcomes. Univariate and multivariate Poisson regressions were performed to determine relative risk ratios (RR).ResultsThere were no mortalities. All neonatal outcomes were similar except for respiratory distress syndrome (RDS), which affected 37% of AIP neonates (versus 21% of controls). AIP neonates required respiratory support (64.8% vs. 51.9%) and continuous positive airway pressure (53.7% vs. 42.1%) for a longer duration. Univariate regression yielded elevated RRs for RDS for AIP (RR 1.78, 95% CI 1.24–2.54), placenta previa (RR = 1.94, 95% CI 1.36–2.76), and placenta previa with bleeding (RR 2.29, 95% CI 1.36–3.86). One episode of bleeding had a RR of 2.43 (95% CI 1.57–3.76), 2 or more episodes had a RR of 2.95 (95% CI 1.96–4.44), and bleeding/abruption as the delivery indication had a RR of 2.57 (95% CI 1.82–3.64). A multivariate regression stratifying for AIP and evaluating the combined and individual associations of AIP, bleeding, placenta previa, and GA, resulted in elevated RRs for placenta previa alone (RR 2.16, 95% CI 1.15–4.06) and placenta previa and bleeding (RR 1.69, 95% CI 1.001–2.85).ConclusionsThe increased incidence of RDS at later gestational ages in AIP is driven by placenta previa. AIP neonates required respiratory support for a longer duration than age-matched controls. Providers should be prepared to counsel expectant parents and care for affected neonates.

Influence of Timing of Antenatal Glucocorticoid Exposure on Umbilical Cord Blood Neurotrophins Concentration in Appropriately Grown and Growth Restricted Very Preterm Infants

Influence of Timing of Antenatal Glucocorticoid Exposure on Umbilical Cord Blood Neurotrophins Concentration in Appropriately Grown and Growth Restricted Very Preterm Infants

Chronic Activation of the MAP Kinase Pathway in Isolated Proximal Tubules of Adult Male Sheep with Antenatal Glucocorticoid Exposure

The administration of antenatal glucocorticoids is a well‐accepted therapeutic approach to improve the survivability of infants; an estimated 100,000 women annually who are in jeopardy of premature delivery are treated with steroids. Although antenatal steroid treatment has clear benefit for pulmonary development and improved mortality of the newborn, the long‐term consequences of glucocorticoid exposure during a critical period in fetal development for the adult offspring are not clear. We established a model of fetal programming in the sheep whereby pregnant ewes are exposed to the same dose of glucocorticoids and at the same period of gestation as that applied clinically. The betamethasone‐exposed (BMX) offspring exhibit indices of cardiovascular dysregulation including elevated blood pressure, a reduced baroreflex response and an imbalance in the kidney and brain renin‐angiotensin systems (RAS). The adult exposed males also exhibit a reduced capacity to excrete a sodium (Na+) load that may contribute to the sustained increase in blood pressure. In this regard, isolated proximal tubule cells from male BMX sheep show an enhanced basal increase in Na+ uptake and an exaggerated Na+ response to angiotensin II (Ang II); however, the natriuretic response to Ang‐(1‐7) is blunted suggesting that antenatal steroid exposure impairs the regulation of Na+ in the proximal tubules of adult males. The present study investigated the downstream signaling events in isolated proximal tubules that may reflect the altered expression of the Ang II‐AT1 receptor and Ang‐(1‐7)‐AT7/Mas receptor pathways by antenatal steroid exposure. Proximal tubules (PTs) were isolated from kidneys of control and BMX adult male sheep (~1.2 years of age) and the soluble PT extracts were initially analyzed by a multiplex intracellular signaling array (Cell Signaling, Danvers MA). The array data revealed that components of the MAP kinase pathway [ERK1/2, p38, JNK] were elevated in the PT extracts from the BMX sheep. We then sought to confirm that the MAP kinase pathway was activated in the PTs of exposed sheep using individual antibodies for the phosphorylated (phospho) and total isoforms for each kinase. The MAP kinase phospho‐ERK1/2 was increased 3.7‐fold in the BMX PTs as compared to the non‐exposed controls [2.28±0.57 vs. 0.62±0.07; n = 4 per group, p&lt;0.05]. The phospho‐p38 isoform was increased 2.6‐fold in the PTs from the exposed BMX sheep as compared to the non‐exposed group [1.46±0.24 vs. 0.57±0.22; n = 4 per group, p&lt;0.05]. The chronic activation of the MAP kinase pathway in the BMX PTs may reflect an attenuated expression of cellular phosphatases. One potential target involved in the regulation of both ERK1/2 and p38 is the dual specificity phosphatase DUSP‐1; however, immunoblot analysis did not reveal a difference in the expression of DUSP‐1 between the BMX and control sheep. In summary, the present data demonstrate that the MAP kinase pathway is chronically stimulated in the tubules of BMX male sheep. We suggest that both an activated Ang II‐AT1 receptor axis and an attenuated Ang‐(1‐7)‐AT7/Mas receptor pathway contribute to the long‐term alteration of the MAP kinase system within the renal tubules that potentially accounts for the altered Na+ handling in this model of glucocorticoid‐dependent fetal programming.Support or Funding InformationNICHD HD084227, HD‐047584 and HD‐017644

The effects of antenatal glucocorticoid exposure on fetal and neonatal skin maturation.

The use of antenatal glucocorticoids in women with preterm labor has dramatically improved outcomes for premature infants. The most commonly used antenatal glucocorticoids are betamethasone and dexamethasone. Glucocorticoids accelerate fetal lung growth by several mechanisms, including the maturation of type II pneumocytes enabling surfactant production. Furthermore, the lipids in the lung share similarity with those in the skin. Therefore, antenatal administration of glucocorticoids may have effects on the structure and function of the developing epidermal barrier in fetuses and neonates. We performed a systematic review to characterize these effects, identifying 11 studies (six animal and five human studies). Five out of the six animal studies used a rodent model for investigating the effects of antenatally administered glucocorticoids, while the other used an ovine model. Antenatally administered glucocorticoids accelerated skin maturation in animal studies, but studies of human fetuses found conflicting results. None of the reviewed studies compared the effects of different types of glucocorticoids. More human studies are needed to fully understand the effects of antenatal steroids. However, as the antenatal use of glucocorticoids in preterm pregnancies has become part of standard clinical practice, it would be unethical to carry out a large randomized controlled trial. We may have to rely on animal models to improve our understanding of the effects of antenatal glucocorticoid exposure on the fetal and neonatal skin maturation.

Significance of antenatal glucocorticoid exposure for pressure injury prevalence in neonates.

Studies have highlighted that antenatal steroids could have an effect on neonatal skin maturation. This study examined if there was a relationship between the administration of antenatal glucocorticoids for mothers and the skin injuries in their neonates. Data from skin injury audit were extracted from the neonatal database and analyzed to determine differences in the prevalence of neonates with pressure injuries [cases] whose mothers had received antenatal steroids, compared to those without pressure injuries [control]. Of 247 neonates audited, 77 [31%], had documented pressure injuries, 170 [69%] had no documented injury. The median birth weight and gestation were 1400 g [IQR 893-2268 g] and 30.3 weeks [IQR 26.3-40.0 weeks] respectively. Of the neonates born less than 34 weeks, 80% were exposed to antenatal steroids and were equally distributed across patient genders. Within the 77 cases, 53 [66%] were exposed to antenatal steroids compared to controls in which 88 [53%] had not. The effect between cases and controls was not statistically significant [χ2 = 2.81, P = 0.09]. However a difference was noted between genders, as female neonates benefited from the exposure to steroids [OR = 0.317, 95% [CI 0.105-0.956], p value -0.041]. Antenatal glucocorticoids appear to be beneficial in reducing pressure injury prevalence in female neonates.

26 Advancement of fetal heart maturation with precocious glucocorticoid treatment is dependent upon maternal genotype

Glucocorticoids are routinely administered to pregnant women at risk of pre-term delivery to mature fetal organs and improve neonatal survival. Here, we tested the hypotheses that (i) antenatal glucocorticoid exposure, prior to the normal increase in glucocorticoid levels, will advance fetal heart maturation and (ii) this would depend on maternal GR genotype. Female GR+/- and GR+/+ mice were crossed with GR+/- males to generate GR+/+ and GR+/- fetuses. GR+/- intercrosses also generated GR-/- (glucocorticoid-resistant controls). Dexamethasone (100 µg/kg/day) or vehicle was administered in the drinking water of pregnant dams from E12.5 (n = 3–6/group), 2d prior to the initiation of fetal glucocorticoid production. In utero high frequency ultrasound was performed at E15.5. Dexamethasone treatment of GR+/+ dams did not affect myocardial performance index (MPI), a measure of systolic and diastolic function, in either GR+/- or GR+/+ fetuses. However, compared to vehicle, dexamethasone treatment of GR+/- dams decreased MPI (indicating improved cardiac function) in their GR+/- fetuses (mean ± SEM: vehicle = 0.746 ± 0.020, dex = 0.620 ± 0.028; P

Sex-specific effect of antenatal betamethasone exposure on renal oxidative stress induced by angiotensins in adult sheep.

Prenatal glucocorticoid administration in clinically relevant doses reduces nephron number and renal function in adulthood and is associated with hypertension. Nephron loss in early life may predispose the kidney to other insults later but whether sex influences increases in renal susceptibility is unclear. Therefore, we determined, in male and female adult sheep, whether antenatal glucocorticoid (betamethasone) exposure increased 8-isoprostane (marker of oxidative stress) and protein excretion after acute nephron reduction and intrarenal infusions of angiotensin peptides. We also examined whether renal proximal tubule cells (PTCs) could contribute to alterations in 8-isoprostane excretion in a sex-specific fashion. In vivo, ANG II significantly increased 8-isoprostane excretion by 49% and protein excretion by 44% in male betamethasone- but not in female betamethasone- or vehicle-treated sheep. ANG-(1-7) decreased 8-isoprostane excretion but did not affect protein excretion in either group. In vitro, ANG II stimulated 8-isoprostane release from PTCs of male but not female betamethasone-treated sheep. Male betamethasone-exposed sheep had increased p47 phox abundance in the renal cortex while superoxide dismutase (SOD) activity was increased only in females. We conclude that antenatal glucocorticoid exposure enhances the susceptibility of the kidney to oxidative stress induced by ANG II in a sex-specific fashion and the renal proximal tubule is one target of the sex-specific effects of antenatal steroids. ANG-(1-7) may mitigate the impact of prenatal glucocorticoids on the kidney. P47 phox activation may be responsible for the increased oxidative stress and proteinuria in males. The protection from renal oxidative stress in females is associated with increased SOD activity.

Glucocorticoids and fetal programming part 2: Mechanisms.

The lifelong health of an individual is shaped during critical periods of development. The fetus is particularly susceptible to internal and external stimuli, many of which can alter developmental trajectories and subsequent susceptibility to disease. Glucocorticoids are critical in normal development of the fetus, as they are involved in the growth and maturation of many organ systems. The surge in fetal glucocorticoid levels that occurs in most mammalian species over the last few days of pregnancy is an important developmental switch leading to fundamental changes in gene regulation in many organs, including the brain. These changes are important for the transition to postnatal life. Exposure of the fetus to increased levels of glucocorticoids, resulting from maternal stress or treatment with synthetic glucocorticoids, can lead to long-term 'programming' of hypothalamic-pituitary-adrenal function and behaviours. Glucocorticoids act at multiple levels within the fetal brain. Growing evidence indicates that they can exert powerful effects on the epigenome, including on DNA methylation, histone acetylation and microRNA, to influence gene expression. Such influences probably represent a critical component of the 'programming' process, and might be partly responsible for the transgenerational effects of antenatal glucocorticoid exposure on neurologic, cardiovascular and metabolic function.

Evidence for an angiotensin‐(1‐7) neuropeptidase in the brain medulla of sheep (1140.6)

Angiotensin‐(1‐7) [Ang 7] is an alternative product of the renin‐angiotensin system (RAS). In contrast to Ang II, Ang 7 exhibits central actions to lower blood pressure and improve baroreflex sensitivity. We identified a thiol‐sensitive peptidase that metabolized Ang 7 to Ang‐(1‐4) (Ang 4) in CSF of adult sheep. This activity was 2.5‐fold higher in sheep with antenatal glucocorticoid exposure while CSF Ang 7 levels were 50% lower compared to controls. To characterize this peptidase, we purified the protein 1400‐fold from the brain medulla by multiple chromatography steps monitored by 125I‐Ang 7 conversion to Ang 4. Chelating agents o‐phenanthroline and EDTA, as well as the mercury compounds APMA and PCMB, but not the cysteine protease inhibitor E64 blocked peptidase activity. Specific inhibitors to neprilysin, neurolysin, or thimet oligopeptidase were ineffective while the activity was abolished by the metallopeptidase inhibitor JMV 390 (Ki = 0.7 nM). HPLC analysis confirmed the processing of unlabeled Ang 7 to Ang 4 by the peptidase, but revealed &lt;5% hydrolysis of Ang II or Ang I and no hydrolysis of neurotensin, bradykinin or apelin. Kinetic studies using 125I‐labeled Ang 7 and Ang I show similar Kms (2.6 and 4.3 μM), but a higher Vmax for Ang 7 (72 vs. 6 nmol/min/mg for Ang I, p&lt;0.01, n=3). We conclude that evidence for an Ang 7 neuropeptidase may portend a novel pathway to influence actions of the peptide within the brain.Grant Funding Source: Supported by HD47584

Antenatal betamethasone increases vascular reactivity to endothelin-1 by upregulation of CD38/cADPR signaling.

Antenatal steroid administration is associated with hypertension in adult life; however, the mechanisms underlying this phenomenon are unclear. The aim of this study was to further characterize the effects of antenatal glucocorticoid exposure on the endothelin (ET-1) system, specifically to ascertain the role of the cyclic adenosine diphosphate ribose (cADPR)/ryanodine receptor pathway in the increased sensitivity to ET-1 observed in the offspring exposed to antenatal glucocorticoids. Pregnant sheep were randomly treated with betamethasone (Beta; 0.17 mg/kg) or vehicle at 80 and 81 days of gestation. In adults, we studied endothelium-denuded arterial segments of the brachial arteries. ET-1-induced vasoconstriction was significantly higher in the arteries from Beta sheep (F=3.5, P<0.05). Inhibition of ADP-ribosyl cyclase with 2-2'-dihydroxy-azobenzene significantly decreased the ET-1-induced contraction in Beta but not in vehicle-treated sheep. Nicotinamide attenuated ET-1 contraction in both, but it was significantly more pronounced in the Beta-treated sheep. No significant differences were observed following KCl-induced (6.25-75 mM) contraction. Nicotinamide (10 mM) significantly attenuated the KCl-induced vasoconstriction in both groups. In KCl (62.5 mM)-constricted arteries, the effect of nicotinamide (NIC) was significantly greater in the vehicle-treated sheep (50% relaxation v. 40% relaxation; t=2.2, P<0.05). In contrast, the sodium nitroprusside (SNP) relaxation was not statistically different. An additive effect was observed when NIC and SNP were used in combination and it was also more pronounced in vehicle-treated sheep. We conclude that the increased response to ET-1 is mediated by activation of the CD38/cADPR signaling pathway. Further studies are required to identify the effectors downstream from cADPR affected by exposure to antenatal steroids.