Dynamics of the fetal adrenal, cholesterol, and apolipoprotein B responses to antenatal betamethasone therapy

Serum cholesterol acceptor capacity in intrauterine growth restricted fetuses

AIM

Intrauterine growth restriction (IUGR) is an independent risk factor for the development of cardiovascular diseases later in life. The mechanisms whereby slowed intrauterine growth confers vascular risk are not clearly established. In general, a disturbed cholesterol efflux has been linked to atherosclerosis. The capacity of serum to accept cholesterol has been repeatedly evaluated in clinical studies by the use of macrophage-based cholesterol efflux assays and, if disturbed, precedes atherosclerotic diseases years before the clinical diagnosis. We now hypothesized that circulating cholesterol acceptors in IUGR sera specifically interfere with cholesterol transport mechanisms leading to diminished cholesterol efflux.

METHODS

RAW264.7 cells were used to determine efflux of [3H]-cholesterol in response to [umbilical cord serum (IUGR), n=20; controls (CTRL), n=20].

RESULTS

Cholesterol efflux was lower in IUGR as compared to controls [controls: mean 7.7% fractional [3H]-cholesterol efflux, standard deviation (SD)=0.98; IUGR: mean 6.3%, SD=0.79; P<0.0001]. Values strongly correlated to HDL (ρ=0.655, P<0.0001) and apoE (ρ=0.510, P=0.0008), and mildly to apoA1 (ρ=0.3926, P=0.0122) concentrations.

CONCLUSIONS

Reduced cholesterol efflux in IUGR could account for the enhanced risk of developing cardiovascular diseases later in life.

Maternal Serum Lipid, Estradiol, and Progesterone Levels in Pregnancy, and the Impact of Placental and Hepatic Pathologies

OBJECTIVE

Lipids and steroid hormones are closely linked. While cholesterol is the substrate for (placental) steroid hormone synthesis, steroid hormones regulate hepatic lipid production. The aim of this study was to quantify circulating steroid hormones and lipid metabolites, and to characterize their interactions in normal and pathological pregnancies with a focus on hepatic and placental pathologies.

METHODS

A total of 216 serum samples were analyzed. Group A consisted of 32 patients with uncomplicated pregnancies who were analyzed at three different time-points in pregnancy (from the first through the third trimester) and once post partum. Group B consisted of 36 patients (24th to 42nd week of gestation) with pregnancy pathologies (IUGR n = 10, preeclampsia n = 13, HELLP n = 6, intrahepatic cholestasis n = 7) and 31 controls with uncomplicated pregnancies. Steroid profiles including estradiol, progesterone, and dehydroepiandrosterone were measured by GC-MS and compared with lipid concentrations.

RESULTS

In Group A, cholesterol and triglycerides correlated positively with estradiol (cholesterol ρ = 0.50, triglycerides ρ = 0.57) and progesterone (ρ = 0.49, ρ = 0.53) and negatively with dehydroepiandrosterone (ρ = - 0.47, ρ = - 0.38). Smoking during pregnancy affected estradiol concentrations, leading to lower levels in the third trimester compared to non-smoking patients (p < 0.05). In Group B, cholesterol levels were found to be lower in IUGR pregnancies and in patients with HELLP syndrome compared to controls (p < 0.05). Steroid hormone concentrations of estradiol (p < 0.05) and progesterone (p < 0.01) were lower in pregnancies with IUGR.

DISCUSSION

Lipid and steroid levels were affected most in IUGR pregnancies, while only minor changes in concentrations were observed for other pregnancy-related disorders. Each of the analyzed entities displayed specific changes. However, since the changes were most obvious in pregnancies complicated by IUGR and only minor changes were observed in pregnancies where patients had impaired liver function, our data suggests that placental rather than maternal hepatic function strongly determines lipid and steroid levels in pregnancy.

Mass spectrometric profiling of cord blood serum proteomes to distinguish infants with intrauterine growth restriction from those who are small for gestational age and from control individuals

Intrauterine growth restriction (IUGR) is a multifactorial condition in that the fetus does not reach its genetically given growth potential. Besides its contribution to perinatal mortality, it is a risk factor for cardiovascular and metabolic diseases later in life. The diagnosis is based on antenatal sonography, which allows differentiating between IUGR and fetuses that are small by constitution (small for gestational age [SGA]). Yet, neither a clinical nor a biochemical tool is available to confirm reliably the diagnosis of IUGR postnatally. Recently, we identified umbilical cord blood proteins of the apolipoprotein family by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with differential signal intensities between the IUGR group and a control group. We hypothesized that identified molecules have the potential to generate a proteome profile specific for IUGR. A total of 114 serum samples (42 from the IUGR group, 12 from the SGA group, and 60 from the control group) of the umbilical vein (99 samples) and umbilical artery (15 samples) were analyzed. Sample quality was estimated by determining the abundance of hemoglobin (hemolysis) and CXC-motif chemokines CXCL4 and CXCL7 (platelet activation). Samples passing the quality criteria were forwarded to multiplex apolipoprotein profiling. Assay performance was tested with the sample sets, resulting in a sensitivity of 0.91 and a specificity of 0.85 in the test set with venous blood samples. Arterial cord blood samples followed the trend (sensitivity, 0.67; specificity, 0.85). SGA samples grouped together with the control samples. We conclude that the proteome profiling signature is confirmatory to clinical surveillance with the potential to identify neonates with IUGR postnatally in low-birth weight babies born at uncertain gestational age when antenatal sonography data have not been recorded.

Measurement of salivary cortisol as a marker of stress in newborns in a neonatal intensive care unit

AIMS

The study was designed to evaluate the newborn (NB) stress response during the inpatient time in the neonatal intensive care unit.

METHODS

A quantitative, prospective, observational study was conducted with two NB groups. The first group consisted of 12 NB patients in the neonatal intensive care unit as the experimental group (EG), and the second included 43 NBs who were sent to their own homes and were considered the control group (CG). The EG's salivary cortisol concentration was measured on the 2nd day (D2) and 9th day (D9) of life. The CG's salivary cortisol concentration was measured on the 14th day of life at the child's own home.

RESULTS

The salivary cortisol concentration levels for the EG on D2 and D9 and for the CG were 4.3151 ± 2.6492, 1.826 ± 1.2252, and 1.0166 ± 0.8300 ng/dl, respectively. These findings indicated the presence of an adrenal response to stress during the first inpatient days.

CONCLUSIONS

The salivary cortisol concentration is an accurate method to indicate neonatal stress. The glucocorticoids frequently used in the prenatal period suppress the adrenal glands and interfere with the stress response.

Placental P-glycoprotein is unaffected by timing of antenatal glucocorticoid therapy but reduced in SGA preterm infants

INTRODUCTION

The beneficial effects of antenatal glucocorticoid therapy on fetal lung maturation require their passage across the placental glucocorticoid barrier, composed of glucocorticoid metabolising enzymes, such as 11 beta hydroxysteroid dehydrogenase (11βHSD), and proteins that efflux glucocorticoids, such as P-glycoprotein (P-gp). We have shown that 11βHSD2 activity is responsive to antenatal glucocorticoids, however the effect on placental P-gp remains unknown. Since antenatal glucocorticoids have a greater prophylactic effect in females compared to males, we also assessed whether this therapy induced sexually dimorphic effects on P-gp expression, as well as on placental inflammatory processes mediated by corticosteroids.

METHODS

Placentas were collected from 53 women presenting in threatened preterm labour, and processed to assess cytokine and P-gp mRNA expression, as well as P-gp localisation using immunohistochemistry.

RESULTS

Placental cytokine, P-gp mRNA and protein expression were not altered by timing of antenatal glucocorticoids or fetal sex. However, both P-gp mRNA and protein expression were significantly reduced in placentas from infants born small for gestational age (SGA) compared to appropriately grown infants (p < 0.05), suggesting a role for P-gp in its pathogenesis via the provision of a net increase in fetal exposure to bioactive exogenous glucocorticoids.

CONCLUSIONS

While this study identified no change in placental P-gp following antenatal glucocorticoids, it has provided evidence that P-gp plays an important role in cases of SGA. This supports the known mechanistic relationship between antenatal glucocorticoids, fetal development and the postnatal phenotype. Given that P-gp also confers fetal protection from a number of drugs, this finding warrants further investigation to improve clinical management of the SGA fetus.

Effects of antenatal corticosteroids on the hypothalamic-pituitary-adrenocortical axis of the fetus and newborn: experimental findings and clinical considerations

The hypothalamic-pituitary-adrenocortical (HPA) axis is a major neuroendocrine pathway that modulates the stress response. The glucocorticoid, cortisol, is the principal end product of the HPA axis in humans and plays a fundamental role in maintaining homeostasis and in fetal maturation and development. Antenatal administration of synthetic glucocorticoids (GCs) accelerates fetal lung maturation and has significantly decreased neonatal mortality and morbidity in infants born before 34 weeks of gestation. Exposure to excess levels of endogenous GCs and exogenous GCs (betamethasone and dexamethasone) has been shown to alter the normal development trajectory. The development and regulation of the fetal HPA axis is discussed and the experimental animal evidence presented suggests long-term adverse consequences of altered HPA function. The clinical data in infants exposed to GCs also suggest altered HPA axis function over the short term. The longer-term consequences of antenatal GC exposure on HPA axis function and subtler neurodevelopmental outcomes including adaptation to stress, cognition, behavior, and the cardiovascular and immune responses are poorly understood. Emerging clinical strategies and interventions may help in the selection of mothers at risk for preterm delivery who would benefit from existing or future formulations of antenatal GCs with a reduction in the associated risk to the fetus and newborn. Detailed longitudinal long-term follow-up of those infants exposed to synthetic GCs are needed.

Glucocorticoid exposure of sheep at 0.7 to 0.75 gestation augments late-gestation fetal stress responses

OBJECTIVES

Exposure to glucocorticoid levels inappropriately high for current maturation alters fetal hypothalamo-pituitary-adrenal axis (HPAA) development. In an established fetal sheep model, we determined whether clinical betamethasone doses used to accelerate fetal lung maturation have persistent effects on fetal HPAA hypotensive-stress responses.

STUDY DESIGN

Pregnant ewes received saline (n = 6) or betamethasone (n = 6); 2 × 110 μg/kg body weight doses injected 24 hours apart (106/107 and 112/113 days' gestational age, term 150 days). Basal adrenocorticotropin (ACTH) and cortisol and responses to fetal hypotension were measured before and 5 days after the first course and 14 days after the second course.

RESULTS

Basal ACTH and cortisol were similar with treatment. HPAA responses to hypotension increased after the second but not first course and ACTH/cortisol ratio increased indicating central HPAA effects.

CONCLUSIONS

Results demonstrate latency in the emergence of fetal HPAA hyperresponsiveness following betamethasone exposure that may explain hyperresponsiveness in full-term but not preterm neonates.

Influence of sex and glucocorticoid exposure on preterm placental pro-oxidant-antioxidant balance

Glucocorticoids (GC) are known to influence fetal ROS production and anti-oxidant defences yet little attention has focused on the potential for effects in the placenta. We hypothesised that antenatal GC exposure alters placental pro-oxidant-anti-oxidant balance sex-specifically, based upon the known relationship between male sex and poor pregnancy outcome. Placentae were collected from 60 women who delivered between 24 and 31 completed weeks gestation and placental oxidative and nitrative stress (protein carbonyl, lipid hydroperoxide, and nitrotyrosine concentration) and anti-oxidant enzyme activity (glutathione peroxidase, thioredoxin reductase, and superoxide dismutase) measured. A pro-oxidant state was observed in placentae of male compared to female infants born within 72 h of antenatal GC exposure, with higher levels of protein carbonyl content (p = 0.04), lipid hydroperoxide (p < 0.01) and nitrotyrosine content (p = 0.02), and lower levels of glutathione peroxidase activity (p = 0.01). A pro-oxidant state continued to be observed in placentae of males compared to females born outside of 72 h, with higher protein carbonyl content (p = 0.04) and lower glutathione peroxidase activity (p = 0.01) than females, however no differences in placental lipid hydroperoxide and nitrotyrosine content were observed. These sex-specific alterations in products of placental oxidative stress could not purely be explained by differences in clinical illness severity (CRIB2 score). Therefore, these sex-specific alterations in placental pro-oxidant-antioxidant balance in response to antenatal betamethasone exposure, independent of illness severity, could contribute to the patho-physiologic processes underlying oxygen radical diseases of the newborn, conditions known to exhibit a male excess.

The influence of sex and antenatal betamethasone exposure on vasoconstrictors and the preterm microvasculature

OBJECTIVE

Dysregulated vascular resistance contributes to hypotension following preterm birth with sex-specific differences in microvascular function conferring a male disadvantage. We hypothesized that glucocorticoid mediated, sex-specific differences in the endogenous catecholamine norepinephrine and endothelially derived endothelin-1 (ET-1) contribute to microvascular dysfunction in preterm neonates in the immediate newborn period.

METHODS

Umbilical and plasma ET-1 and normetanephrine, in 24 h urine samples, were determined at 24, 72, and 120 h of age in 24-34 week infants (n = 60). Microvascular blood flow was determined by laser Doppler flowmetry.

RESULTS

In infants born within 72 h of antenatal glucocorticoid exposure, normetanephrine was higher in females than males (p = 0.048). Normetanephrine was inversely correlated with both microvascular blood flow at 24 h (p = 0.025) and CRIB II (p = 0.001). While umbilical arterial ET-1 was higher in females delivered <72 h after antenatal betamethasone (p = 0.006), plasma ET-1 did not correlate with microvascular blood flow or illness severity. Only sex and normetanephrine contributed significantly to both microvascular blood flow and endothelium dependant vasodilatation.

CONCLUSIONS

These data support glucocorticoid mediated, sex-specific differences in mediators of vascular tone that may contribute to the impaired mechanisms compromising successful hemodynamic adaption to neonatal life and resulting in excess male morbidity and mortality.

Prenatal treatment with glucocorticoids sensitizes the hpa axis response to stress among full-term infants

The objective of this study was to determine the consequences for HPA axis functioning among healthy full-term newborns of prenatal treatment with the synthetic glucocorticoid (GC), betamethasone, which is the routine treatment for threatened preterm delivery. Ninety full-term infants were recruited into two study groups (30 betamethasone treated; 60 comparison group matched for GA at birth and sex). The cortisol and behavioral response to the painful stress of a heel-stick blood draw was assessed 24 hr after birth. Full-term infants exposed to prenatal betamethasone displayed a larger cortisol response to the heel-stick procedure, despite no differences in baseline levels. Further, within the recommended window of betamethasone administration (24-34 gestational weeks), infants exposed to betamethasone earlier in gestation displayed the largest cortisol response to the heel-stick. These data add to accumulating evidence that prenatal exposure to elevated GCs programs the development of the HPA axis.

Effects of intrauterine exposure to synthetic glucocorticoids on fetal, newborn, and infant hypothalamic-pituitary-adrenal axis function in humans: a systematic review

BACKGROUND

Synthetic glucocorticoids are commonly used in reproductive medicine. Fetal organ systems are highly sensitive to changes in the intrauterine environment, including overexposure to glucocorticoids. Structural and functional alterations resulting from such changes may persist throughout life and have been associated with diverse diseases. One system that could be particularly sensitive to fetal glucocorticoid overexposure is the hypothalamic-pituitary-adrenal (hpa) axis. Many human studies have investigated this possibility, but a systematic review to identify consistent, emergent findings is lacking.

METHODS

We systematically review 49 human studies, assessing the effects of intrauterine exposure to synthetic glucocorticoids on fetal, neonate, and infant hpa function.

RESULTS

Study quality varied considerably, but the main findings held true after restricting the analyses to higher-quality studies: intrauterine exposure to synthetic glucocorticoids reduces offspring hpa activity under unstimulated conditions after pain but not pharmacological challenge. Although reduced unstimulated hpa function appears to recover within the first 2 wk postpartum, blunted hpa reactivity to pain is likely to persist throughout the first 4 months of life. There is some evidence that the magnitude of the effects is correlated with the total amount of glucocorticoids administered and varies with the time interval between glucocorticoid exposure and hpa assessment.

CONCLUSIONS

This systematic review has allowed the demonstration of the way in which intrauterine exposure to various regimens of synthetic glucocorticoids affects various forms of hpa function. As such, it guides future studies in terms of which variables need to be focused on in order to further strengthen the understanding of such therapy, whilst continuing to profit from its clinical benefits.

Sex-specific alterations in placental 11β-hydroxysteroid dehydrogenase 2 activity and early postnatal clinical course following antenatal betamethasone

Placental 11β-hydroxysteroid dehydrogenase-2 (11βHSD2) limits fetal glucocorticoid exposure and is associated with physiological stability in the premature newborn infant. Antenatal betamethasone alters 11βHSD2 activity and confers sex-specific advantages in neonatal outcome. We investigated the influence of betamethasone and sex on 11βHSD2 activity, neonatal adrenal function and clinical course in 24- to 36-wk gestation neonates from birth to day 5 of life. Univariate analyses demonstrated an interaction between timing of betamethasone exposure and sex for 11βHSD2 activity rate ( P = 0.02) and umbilical arterial cortisol ( P = 0.01). For infants born < 72 h following antenatal betamethasone, females had higher 11βHSD2 activity ( P < 0.01) and umbilical arterial cortisol ( P = 0.01) than males. Females born < 72 h of betamethasone exposure had higher day 1 urinary cortisol, if exposed to perinatal stress, than males ( P < 0.01). For infants born < 72 h after betamethasone exposure, 11βHSD2 activity was negatively correlated with Clinical Illness Severity Score score ( r = −0.79 P = 0.01) and positively correlated with mean arterial blood pressure ( r = 0.8 P = 0.01) only in females. Sex-specific placental 11BHSD2 autoregulation following antenatal betamethasone exposure may limit adrenal suppression in females influencing physiological stability following preterm birth. A lack of adjustment in 11βHSD2 and adrenal response may contribute to the increased incidence of poor outcome observed in preterm males.

Changes in human placental 5alpha-reductase isoenzyme expression with advancing gestation: effects of fetal sex and glucocorticoid exposure

5alpha-reduced steroids, including allopregnanolone, suppress neuronal activity and can have neuroprotective effects in the fetus. 5alpha-reductases in the placenta may contribute precursors to brain allopregnanolone synthesis. Preterm birth and glucocorticoids, administered for fetal lung maturation or for maternal asthma, may influence reductase expression. The aims of the present study were to evaluate placental 5alpha-reductase isoform expression during late gestation and to examine fetal sex differences and the effects of glucocorticoid therapies on the expression of these enzymes. Expression of the two 5alpha-reductase isoenzymes was measured in placental samples, whereas cortisol concentrations were measured in cord blood, from two cohorts. The first cohort consisted of women who delivered preterm and received betamethasone treatment (n=41); the second cohort consisted of women who delivered at term and were either healthy controls (n=30) or asthmatics who had used glucocorticoids (n=24). Placental expression of both isoenzymes increased with advancing gestation and there were marked sex differences in levels of 5alpha-reductase I (P<0.05), but not of 5alpha-reductase II. The expression of both enzymes was positively correlated with cortisol levels (P<0.05), but there was no effect of recent glucocorticoid exposure. These findings suggest that the preterm neonate may have lower developmental exposure to 5alpha-reduced steroids and may lack steroid-mediated neuroprotection depending on fetal sex.

Antenatal betamethasone administration alters stress physiology in healthy neonates

OBJECTIVE

To analyze hypothalamic-pituitary-adrenal axis balance in healthy newborns after antenatal betamethasone treatment for lung maturation where delivery could be prolonged until or near term.

METHODS

In a prospective observational study, salivary cortisol and cortisone levels were measured at the fourth day of life during resting conditions and in response to a pain-induced stress event in 23 neonates with antenatal exposure to a single course of betamethasone (2x12 mg) and compared with 40 controls. The mean interval between betamethasone treatment and delivery was 60+/-23 days.

RESULTS

On day 4 of life, neonates in the control group exhibited a significant increase in cortisol and cortisone from baseline levels after the stress induction (1.175-2.4 ng/mL for cortisol and 11.35-18.15 ng/mL for cortisone [both P<.05]), whereas, in betamethasone-exposed neonates, cortisol and cortisone stress response was not significantly different from baseline levels (1.39-1.6 ng/mL for cortisone [P=.76] and 14.8-17.1 ng/mL for cortisol [P=.69]). No influence of gestational age at betamethasone administration (P=.76) or gestational age at delivery (P=.71) on stress response patterns was observed in a multiple stepwise regression.

CONCLUSION

A single course of antenatal betamethasone treatment induces a suppression of stress reactivity in healthy newborns.

Antenatal betamethasone depresses maternal and fetal aldosterone levels

Antenatal glucocorticoids are used to mature lung function in fetuses at risk for preterm delivery, but they also suppress cortisol synthesis in both pregnant women and their fetuses. We recently discovered in pregnant rabbits that even though exogenous betamethasone is not a mineralocorticoid, it also suppresses production of aldosterone. Lower aldosterone levels were linked to reduced P450 side chain cleavage(P450scc) messenger RNA levels in the rabbit maternal and fetal adrenal cortex. To establish whether this occurs in humans, we assayed aldosterone levels in women and newborns treated with antenatal betamethasone for preterm labor. In mothers treated with betamethasone, maternal cortisol depression after 48 hours was accompanied by aldosterone depression. Both pregnant women and their newborns treated with betamethasone showed depressed aldosterone levels in a 1- to 3-day period after the first betamethasone dose. We conclude that suppression of aldosterone biosynthesis is a side effect of antenatal steroids that has been largely overlooked, but may be clinically relevant at a time when the newborn is learning to control plasma electrolytes and blood volume.

Relation of glucose control in diabetic pregnancy to fetal cholesterol homeostasis

OBJECTIVE

To determine the impact of maternal diabetic glucose control on fetal cholesterol homeostasis.

METHODS

Singleton pregnancies of 150 women complicated by gestational (n = 90) and pre-gestational (n = 60) diabetes were evaluated. Those with insulin-requiring diabetes had fasting blood glucose levels determined daily during the last 4 weeks of pregnancy and weekly fasting glucose values were obtained in those with A1 (diet-controlled) gestational diabetes. Umbilical cord venous serum was collected at delivery and total cholesterol levels were determined.

RESULTS

Among the 150 women, 69 had A1 gestational diabetes and 81 were insulin-requiring. Fasting glucose levels were inversely correlated (p < 0.001) to gestational age, regardless of diabetes classification. Umbilical serum cholesterol levels were inversely related (p < 0.002) to gestational age and weight, but did not vary according to diabetic classification. Among term infants (n = 110), umbilical serum cholesterol levels were inversely related to maternal fasting glucose levels at 4 weeks (p = 0.006) and 2 weeks (p = 0.006) before delivery.

CONCLUSION

Maternal hyperglycemia is associated with decreased plasma fetal cholesterol levels in term infants.

The regulation of adrenocorticotrophic hormone receptor by corticotropin-releasing hormone in human fetal adrenal definitive/transitional zone cells

As gestation progresses, human fetal adrenals (HFA) initiate the production of cortisol, which increases placental corticotropin-releasing hormone (CRH) biosynthesis. While adrenocorticotrophic hormone (ACTH) is important for the onset of cortisol production, the late gestational surge in cortisol production occurs despite falling ACTH levels in the fetal circulation. The authors determine if CRH directly regulates the expression of the ACTH receptor (ACTHR) in HFA definitive/transitional zone (DZ/TZ) cells. DZ/TZ cells isolated from midgestation HFA were cultured before treatment with 0.01 nM to 100 nM CRH or ACTH. Cortisol was measured by radioimmunoassay. Real-time reverse-transcriptase polymerase chain reaction was used to measure ACTHR mRNA. Whole-cell ACTH binding studies were performed using I(125) (Tyr-23) ACTH. CRH produced a dose-dependent rise in cortisol production and caused a time-dependent increase in ACTHR mRNA levels between 12 and 24 hours. As little as 0.1 nM CRH induced ACTHR transcript by 12-fold at 24 hours. Together with ACTH 0.01 nM, 0.03 or 0.1 nM CRH increased ACTHR expression more than ACTH alone. Binding assays demonstrated a 3.5-fold increase in ACTHR protein at 48 hours with combined CRH and ACTH treatment. Physiologic levels of CRH seen in the late-gestation fetus stimulate DZ/TZ ACTHR expression. Since placental CRH production increases strikingly near the end of gestation, the authors suggest that CRH-induced ACTH receptor expression may increase TZ responsiveness to circulating ACTH and contribute to the late gestational rise in cortisol secretion by the HFA, participating in an endocrine cascade that is involved in fetal organ maturation and potentially in the timing of human parturition.

Antenatal betamethasone treatment has a persisting influence on infant HPA axis regulation

OBJECTIVE

To examine the consequences of antenatal betamethasone (AB) exposure on postnatal stress regulation.

STUDY DESIGN

Fourteen AB exposed infants born at 28-30 weeks' gestation were assessed in the NICU during postnatal week 1 and at 34 weeks postconception. Nine infants born at 34 weeks gestation without AB treatment were evaluated as a postconceptional age comparison group. Salivary cortisol, heart rate, and behavior were measured at baseline and in response to a heelstick blood draw.

RESULTS

Repeated measures ANOVAs revealed that both groups displayed an increase in heart rate and behavioral distress in response to the stressor. The cortisol response, however, was blunted in AB-treated infants at both assessments.

CONCLUSION

AB treatment has consequences for hypothalamic-pituitary-adrenal (HPA) axis regulation that persist for at least four to six weeks after birth, indicating that studies of long-term effects are warranted.

Sexually dimorphic effects of maternal asthma during pregnancy on placental glucocorticoid metabolism and fetal growth

Human pregnancy is associated with sexually dimorphic differences in mortality and morbidity of the fetus with the male fetus experiencing the poorest outcome following complications such as pre-eclampsia, pre-term delivery and infection. The physiological mechanisms that confer these differences have not been well characterised in the human. Work conducted on the effect of maternal asthma during pregnancy, combining data collected from the mother, placenta and fetus has found some significant sex-related mechanistic differences associated with fetal growth in both normal pregnancies and pregnancies complicated by asthma. Specifically, sexually dimorphic differences have been found in placental glucocorticoid metabolism in male and female fetuses of normal pregnancies. In response to the presence of maternal asthma, only the female fetus alters placental glucocorticoid metabolism resulting in decreased growth. The male fetus does not alter placental function or growth in response to maternal asthma. As a result of the alterations in glucocorticoid metabolism in the female, downstream changes occur in pathways regulated by glucocorticoids. These data suggest that the female fetus adjusts placental function and reduces growth to compensate for maternal disease. However, the male fetus continues to grow in response to maternal asthma with no changes in placental function. This response by the male fetus may partially contribute to the increased risk of morbidity and mortality in this sex.

Steroid Sulfotransferase 2A1 Gene Transcription Is Regulated by Steroidogenic Factor 1 and GATA-6 in the Human Adrenal

Sulfonation is a phase II conjugation reaction responsible for the biotransformation of many compounds including steroids, bile acids, and drugs. Humans are presently known to express at least five cytosolic sulfotransferase (SULT) enzymes, of which only two are hydroxysteroid SULT, SULT2A1, commonly known as steroid sulfotransferase, and the cholesterol sulfotransferase SULT2B1. SULT2A1 is highly expressed in the adrenal where it is responsible for the sulfation of hydroxysteroids including conversion of dehydroepiandrosterone to dehydroepiandrosterone sulfate and in the liver where it is responsible for sulfation of bile acids and circulating hydroxysteroids. Little is known concerning the transcriptional regulation of human SULT2A1 in adrenal. Herein we demonstrate the role of two transcription factors, steroidogenic factor 1 (SF1) and GATA-6, in the regulation of SULT2A1 transcription. These transcription factors were quantified by real-time RT-PCR in normal human adrenal tissue. Transient transfection assays with deleted and mutated SULT2A1 promoter constructs allowed for the determination of specific SF1 and GATA binding cis-regulatory elements necessary for transactivation of SULT2A1 promoter, and binding was confirmed by EMSA analysis. Both SF1 and GATA-6 were positive regulators of SULT2A1 promoter constructs. These data support the hypothesis that adrenal SULT2A1 expression is regulated by SF1 and GATA-6.

Effects of prenatal betamethasone exposure on regulation of stress physiology in healthy premature infants

The objective of this study was to examine the effects of prenatal exposure to betamethasone, a corticosteroid, on postnatal stress regulation, particularly activity of the hypothalamic-pituitary-adrenocortical (HPA) axis. Effects were assessed by measuring salivary cortisol production at baseline and in response to two potentially stressful events, a heel-stick blood draw and a physical exam, in infants born at 33-34 weeks gestation. Subjects included 9 infants with antenatal betamethasone treatment (2 doses of 12 mg of betamethasone administered intramuscularly to the mother twelve hours apart) and 9 infants without such treatment. Testing took place 3-6 days after delivery. Measures of behavioral distress confirmed that both events were stressful to these premature infants. Infants with betamethasone exposure, however, failed to exhibit increases in cortisol to either stressor. In contrast, infants without betamethasone exposure displayed elevated cortisol to the heel-stick blood draw but not the physical exam. These findings suggest that antenatal corticosteroids suppress infants' HPA response to a stressor typically encountered in a neonatal intensive care situation.

Drugs that affect the fetus and newborn infant via the placenta or breast milk

In general, drugs that are taken by a mother during pregnancy or after birth may be transferred to the fetus or the infant (through breast milk). Many factors are involved that determine the amount of drugs that are transferred and their potential effects on the fetus or infant. A careful assessment of the risk versus benefit is necessary and should be individualized. In the breastfed infant, many measures can be undertaken further so that the amount of drug transferred to the infant is minimized.

Management of fetal endocrine disorders

A number of maternal endocrine disorders, when active during pregnancy, can have adverse effects on the newborn. Frequently, these affects can be anticipated as in Graves' disease, or the adverse effect can be prevented as in macrosomia in the infant of the diabetic mother. Occasionally, there are opportunities for prenatal treatment of a fetal endocrine disorder. For instance, a large goitre that may cause problems during delivery can be treated with thyroid hormones administered intra-amniotically or as analogues that cross the placenta. A uniquely effective form of treatment for prevention of a major birth defect is administration of dexamethasone to the mother to avoid virilisation of a female fetus with congenital adrenal hyperplasia (CAH). However, such treatment should only be conducted within the framework of a clinical trial as the long-term effects of exposure to potent glucocorticoids in utero are unknown. Intrauterine growth retardation, which affects about 5% of newborns, is currently not amenable to direct pharmacological treatment before birth. However, there are more practical options for managing this condition, including improved maternal nutrition and avoidance of toxins injurious to fetal growth.

Leptin in pregnancy

Leptin is a 16-kDa polypeptide, encoded in humans by the LEP gene. This protein is probably involved in the regulation of ovarian function, oocyte maturation and embryo development, and in the implantation process. During pregnancy, leptin is produced in the placenta; its values increase in the maternal blood particularly in the second trimester and decline postpartum. Leptin levels may be abnormally high in pregnancies complicated by conditions such as diabetes mellitus and pre-eclampsia. The role of leptin in fetal physiology has not been clarified, although cord blood values correlate significantly with birth weight. It is expected that further research will provide new insight into the physiological importance of leptin in the pregnant woman and fetus.

The effect of multidose antenatal betamethasone on maternal and infant outcomes

OBJECTIVE

This study was undertaken to determine whether prolonged betamethasone therapy is, as has been suggested, associated with adverse maternal or neonatal outcomes.

STUDY DESIGN

A secondary multivariate analysis of a randomized controlled trial was performed to determine whether duration of betamethasone therapy was associated with adverse maternal or neonatal outcomes.

RESULTS

There were 414 fetuses whose mothers were randomly assigned to trial groups. Final models included only valid cases without missing or averaged data (N = 367 to N = 412, depending on the model). Three or more sets of weekly betamethasone injections were given in 21.3% of cases and > or =4 sets were given in 12.3% of cases. Prolonged antenatal betamethasone therapy was not associated with increases in incidences of antenatal fever, chorioamnionitis, reduced birth weight, suppressed neonatal adrenal function, neonatal sepsis, or neonatal death. It was associated with larger birth weights (P <.05).

CONCLUSION

Prolonged antenatal betamethasone therapy was not associated with higher risks of antenatal maternal fever, chorioamnionitis, reduced birth weight, neonatal adrenal suppression, neonatal sepsis, and neonatal death.

Reference range for serum cortisol in well preterm infants

AIM

To establish a reference range for serum cortisol concentrations in preterm infants with a gestational age of less than 30 weeks during the first two weeks of life.

METHODS

Infants were prospectively classified by the following exclusion criteria: surfactant administration, arterial hypotension, acute or uncontrolled infection, ventricular haemorrhage II degrees or above, serum glucose < 2.2 mmol/l, exchange transfusion, stress as a result of any kind of examination or nursing for at least 4 hours before blood sampling. The cortisol value was measured once using radioimmunoassay in each infant.

RESULTS

In appropriate for gestational age (AGA) infants (n = 37, median gestational age 27.7 weeks, median birthweight 1030 g) the distribution of the cortisol concentrations was non-Gaussian. These had a nearly normal distribution, when log(10) values of the data were used. The points determined by mean (2 SD) on the logarithmic scale were transformed back to the original units to provide a reference range: 73-562 nmol/l. Gestational age was significantly (p = 0.033) associated with cortisol values (log(10)) with a regression coefficient (standard error) of -0.045 (0.020). Small for gestational age (SGA) infants (n = 8) had significantly higher cortisol values (median 357 nmol/l) than AGA infants (median 199 nmol/l) (p=0.028).

CONCLUSIONS

There is a strictly defined reference range of serum cortisol concentrations in AGA preterm infants.

Dehydroepiandrosterone and dehydroepiandrosterone sulfate production in the human adrenal during development and aging

Dehydroepiandrosterone (DHEA) is produced in prodigious quantities by the human adrenal, principally as the 3-sulfoconjugate DHEA sulfate (DS) during intrauterine life. The fetal zone and neocortex cells of the fetal adrenal express large amounts of DHEA sulfotransferase and minimal amounts, at least until very near the end of gestation, of 3beta-hydroxysteroid dehydrogenase. This pattern of enzyme expression favors substantial secretion of DHEA/DS with minimal cortisol produced; the DHEA/DS serves as the major precursor for placental estrogen formation in human pregnancy. Aside from adrenocorticotropin, other physiologic regulators of growth and steroidogenesis in the fetal adrenal have been postulated to exist, but have yet to be identified. Whereas intrauterine stressors may activate adrenal cortisol secretion, the fetal adrenal responds to many pregnancy conditions by suppressing DHEA/DS formation. After birth, the human adrenal undergoes reorganization whereby the large, inner fetal zone regresses, and DHEA/DS production is diminished. Just prior to gonadal maturation, the human adrenal undergoes morphologic and functional changes (adrenarche) that give rise to a prominent zona reticularis that is characterized by the presence of DHEA sulfotransferase, the absence of 3beta-hydroxysteroid dehydrogenase, and an enhancement of DHEA/DS production. The adrenal of the adult responds to stress in many instances like that of the fetus: increased cortisol secretion and diminished DHEA/DS secretion. The mechanisms for this divergence in the adrenocortical pathway is unknown. With aging, there is suppression of DHEA/DS secretion, possibly as the consequence of an involution of the zona reticularis, but corticosteroid production continues unabated.

Effects of maternal infections on fetal adrenal steroid production

We sought to determine the effect of maternal infections on the fetal hypothalamic-pituitary-adrenal axis. Umbilical cord blood was collected at vaginal delivery after labor (24-44 wk. gestation) from 361 infants of women having normal pregnancy ( apart from preterm delivery in some) and 110 infants of women diagnosed with infections: 86% of these women had amnionitis. Infants exposed to antenatal corticosteroids, being growth retarded, or having developmental abnormalities that would be expected to alter function of the hypothalamic-pituitary unit were excluded. Umbilical cord serum was assayed for dehydroepiandrosterone sulfate (DS) and for cortisol. The data were analyzed by use of SAS. The gestational age of the infants of normal women (35.8+/-0.2 wk., Mean +/- SE) was greater than that of the infants of women having infections (34.3+/-0.4 wk., P = 0.003). Umbilical cord serum levels of DS and cortisol rose as a function of gestational age in both groups of infants (P<0.01). Despite being, on average, 1 wk. younger than the normal infants are, the infants of women having infections during pregnancy had higher serum levels of cortisol and DS than did those infants of the normal women. These data are consistent with activation of the fetal hypothalamic-pituitary-adrenal axis in pregnancies complicated by maternal infections. Such a fetal response could be the consequence of transplacental passage of products of the activated maternal immune system.

Repeated use of betamethasone in rabbits: effects of treatment variation on adrenal suppression, pulmonary maturation, and pregnancy outcome

OBJECTIVE

The aim of the study was to determine whether reduced birth weight, adrenal suppression, and lung maturation occur in parallel and are cumulative with increasing courses of betamethasone.

STUDY DESIGN

Time-bred rabbits were assigned to a control group or to receive saline solution or 1, 2, or 3 courses of betamethasone (early treatment, beginning day 19). Two additional groups (n = 5 per group) were given 1 or 2 late courses (late treatment). Birth weight, serum cortisol, adrenal 17alpha-hydroxylase (P450c17) messenger ribonucleic acid and fetal lung surfactant proteins A and B were quantified on day 27.

RESULTS

Fetal weight was inversely proportional to the number of courses, with late treatment having a greater effect. Maternal cortisol and P450c17 levels were progressively suppressed with each early course, but fetal cortisol and P450c17 levels were only suppressed after 3 courses. A single late treatment profoundly suppressed both maternal and fetal cortisol and P450c17 messenger ribonucleic acid levels. In contrast, fetal lung surfactant proteins A and B increased progressively with betamethasone courses, regardless of timing.

CONCLUSIONS

Time from last injection to delivery determined adrenal suppression, whereas total betamethasone courses determined surfactant protein production. Lower birth weight was dependent on the number of courses and was greater with late treatment.

Timing of peak serum cortisol values in preterm infants in low-dose and the standard ACTH tests

The low-dose ACTH test seems to reveal mild cases of adrenal insufficiency and is beginning to be preferred over the standard ACTH test in the evaluation of adrenal suppression both in infants and in adults. The concentration-time profile of plasma cortisol in infants after a low ACTH dose is obscure. In this crossover study, we compared timing of the peak values in the low-dose and the standard ACTH stimulation tests in preterm and full-term infants. We performed the standard ACTH tests (250 microg/1.73 m2) and the low-dose ACTH tests (1 microg/1.73 m2) on 10 infants (26-40 wk gestational age) and measured serum cortisol concentration at 0, 30, 40, 60, and 120 min by RIA. Nine of the infants had received postnatal glucocorticoid treatment, and most of them had also been treated with dexamethasone antenatally. In the low-dose test, the peak values occurred at 30 or 40 min in 9/10 patients. In the standard-dose test, the peak values occurred at 60 or 120 min in 8/10 patients. These results are comparable with those from adults. According to this study, blood samples for the low-dose ACTH test in infants should be taken before dosing and between 30 and 40 min after dosing.