The impact of corticosteroids on the developing animal

Astrocyte-derived lactate in stress disorders

Stress disorders are psychiatric disorders arising following stressful or traumatic events. They could deleteriously affect an individual's health because they often co-occur with mental illnesses. Considerable attention has been focused on neurons when considering the neurobiology of stress disorders. However, like other mental health conditions, recent studies have highlighted the importance of astrocytes in the pathophysiology of stress-related disorders. In addition to their structural and homeostatic support role, astrocytes actively serve several functions in regulating synaptic transmission and plasticity, protecting neurons from toxic compounds, and providing metabolic support for neurons. The astrocyte-neuron lactate shuttle model sets forth the importance of astrocytes in providing lactate for the metabolic supply of neurons under intense activity. Lactate also plays a role as a signaling molecule and has been recently studied regarding its antidepressant activity. This review discusses the involvement of astrocytes and brain energy metabolism in stress and further reflects on the importance of lactate as an energy supply in the brain and its emerging antidepressant role in stress-related disorders.

Determination of dexamethasone dose for cortisol suppression in adult common marmosets (Callithrix jacchus)

We conducted a dose-response study of dexamethasone to investigate an optimal dexamethasone suppression test for common marmosets. Twelve marmosets received 0.1, 0.5, or 1.0 mg/kg dexamethasone. Doses of 0.5 and 1.0 mg/kg both suppressed endogenous cortisol for at least 18 h with greater individual variability in the lower 0.5 mg/kg dose.

Emerging concepts and opportunities for endocrine disruptor screening of the non-EATS modalities

Endocrine disrupting chemicals (EDCs) are ubiquitous in the environment and involve diverse chemical-receptor interactions that can perturb hormone signaling. The Organization for Economic Co-operation and Development has validated several EDC-receptor bioassays to detect endocrine active chemicals and has established guidelines for regulatory testing of EDCs. Focus on testing over the past decade has been initially directed to EATS modalities (estrogen, androgen, thyroid, and steroidogenesis) and validated tests for chemicals that exert effects through non-EATS modalities are less established. Due to recognition that EDCs are vast in their mechanisms of action, novel bioassays are needed to capture the full scope of activity. Here, we highlight the need for validated assays that detect non-EATS modalities and discuss major international efforts underway to develop such tools for regulatory purposes, focusing on non-EATS modalities of high concern (i.e., retinoic acid, aryl hydrocarbon receptor, peroxisome proliferator-activated receptor, and glucocorticoid signaling). Two case studies are presented with strong evidence amongst animals and human studies for non-EATS disruption and associations with wildlife and human disease. This includes metabolic syndrome and insulin signaling (case study 1) and chemicals that impact the cardiovascular system (case study 2). This is relevant as obesity and cardiovascular disease represent two of the most significant health-related crises of our time. Lastly, emerging topics related to EDCs are discussed, including recognition of crosstalk between the EATS and non-EATS axis, complex mixtures containing a variety of EDCs, adverse outcome pathways for chemicals acting through non-EATS mechanisms, and novel models for testing chemicals. Recommendations and considerations for evaluating non-EATS modalities are proposed. Moving forward, improved understanding of the non-EATS modalities will lead to integrated testing strategies that can be used in regulatory bodies to protect environmental, animal, and human health from harmful environmental chemicals.

Neuronal and cardiac toxicity of pharmacological compounds identified through transcriptomic analysis of human pluripotent stem cell-derived embryoid bodies

Concurrent with the '3R' principle, the embryonic stem cell test (EST) using mouse embryonic stem cells, developed in 2000, remains the solely accepted in vitro method for embryotoxicity testing. However, the scope and implementation of EST for embryotoxicity screening, compliant with regulatory requirements, are limited. This is due to its technical complexity, long testing period, labor-intensive methodology, and limited endpoint data, leading to misclassification of embryotoxic potential. In this study, we used human induced pluripotent stem cell (hiPSC)-derived embryoid bodies (EB) as an in vitro model to investigate the embryotoxic effects of a carefully selected set of pharmacological compounds. Morphology, viability, and differentiation potential were investigated after exposing EBs to folic acid, all-trans-retinoic acid, dexamethasone, and valproic acid for 15 days. The results showed that the compounds differentially repressed cell growth, compromised morphology, and triggered apoptosis in the EBs. Further, transcriptomics was employed to compare subtle temporal changes between treated and untreated cultures. Gene ontology and pathway analysis revealed that dysregulation of a large number of genes strongly correlated with impaired neuroectoderm and cardiac mesoderm formation. This aberrant gene expression pattern was associated with several disorders of the brain like mental retardation, multiple sclerosis, stroke and of the heart like dilated cardiomyopathy, ventricular tachycardia, and ventricular arrhythmia. Lastly, these in vitro findings were validated using in ovo chick embryo model. Taken together, pharmacological compound or drug-induced defective EB development from hiPSCs could potentially be used as a suitable in vitro platform for embryotoxicity screening.

Pharmacology for Preterm Labor

Preterm birth occurs with 10% of deliveries and yet accounts for more than 85% of perinatal morbidity and mortality. Management of preterm labor prior to delivery includes a multipronged pharmacologic approach targeting utilization of reproductive hormones for continuation of pregnancy, advancement of fetal lung maturity, and the decrease of uterine contractility (tocolysis). This article will review and compare guidelines on pharmacologic management of preterm labor as recommended by the American College of Obstetricians and Gynecologists and the European Association of Perinatal Medicine. The classifications of drugs discussed include exogenous progesterone, corticosteroids, and tocolytics (β-adrenergic agonists, magnesium sulfate, calcium channel blockers, prostaglandin inhibitors, nitrates, and oxytocin receptor blockers). For each of these drug classes, the following information will be presented: mechanism of action, maternal/fetal side effects, and nursing implications.

Maternal hormonal milieu influence on fetal brain development

An adverse maternal hormonal environment during pregnancy can be associated with abnormal brain growth. Subtle changes in fetal brain development have been observed even for maternal hormone levels within the currently accepted physiologic ranges. In this review, we provide an update of the research data on maternal hormonal impact on fetal neurodevelopment, giving particular emphasis to thyroid hormones and glucocorticoids. Thyroid hormones are required for normal brain development. Despite serum TSH appearing to be the most accurate indicator of thyroid function in pregnancy, maternal serum free T4 levels in the first trimester of pregnancy are the major determinant of postnatal psychomotor development. Even a transient period of maternal hypothyroxinemia at the beginning of neurogenesis can confer a higher risk of expressive language and nonverbal cognitive delays in offspring. Nevertheless, most recent clinical guidelines advocate for targeted high-risk case finding during first trimester of pregnancy despite universal thyroid function screening. Corticosteroids are determinant in suppressing cell proliferation and stimulating terminal differentiation, a fundamental switch for the maturation of fetal organs. Not surprisingly, intrauterine exposure to stress or high levels of glucocorticoids, endogenous or synthetic, has a molecular and structural impact on brain development and appears to impair cognition and increase anxiety and reactivity to stress. Limbic regions, such as hippocampus and amygdala, are particularly sensitive. Repeated doses of prenatal corticosteroids seem to have short-term benefits of less respiratory distress and fewer serious health problems in offspring. Nevertheless, neurodevelopmental growth in later childhood and adulthood needs further clarification. Future studies should address the relevance of monitoring the level of thyroid hormones and corticosteroids during pregnancy in the risk stratification for impaired postnatal neurodevelopment.

Influence of postnatal glucocorticoids on hippocampal-dependent learning varies with elevation patterns and administration methods

Recent interest in the lasting effects of early-life stress has expanded to include effects on cognitive performance. An increase in circulating glucocorticoids is induced by stress exposure and glucocorticoid effects on the hippocampus likely underlie many of the cognitive consequences. Here we review studies showing that corticosterone administered to young rats at the conclusion of the stress-hyporesponsiveness period affects later performance in hippocampally-mediated trace eyeblink conditioning. The nature and even direction of these effects varies with the elevation patterns (level, duration, temporal fluctuation) achieved by different administration methods. We present new time course data indicating that constant glucocorticoid elevations generally corresponded with hippocampus-mediated learning deficits, whereas acute, cyclical elevations corresponded with improved initial acquisition. Sensitivity was greater for males than for females. Further, changes in hippocampal neurogenesis paralleled some but not all effects. The findings demonstrate that specific patterns of glucocorticoid elevation produced by different drug administration procedures can have markedly different, sex-specific consequences on basic cognitive performance and underlying hippocampal physiology. Implications of these findings for glucocorticoid medications prescribed in childhood are discussed.

Improving growth in preterm infants during initial hospital stay: principles into practice

Despite recent innovations in nutritional care, postnatal growth failure between birth and hospital discharge remains a significant problem in preterm infants. Whether or not it is entirely preventable is unclear. What is clear is that feeding practices and growth outcomes vary widely between neonatal intensive care units (NICUs). This partly reflects lack of data in key areas but it also reflects inconsistent translation of principles into practice and limitations in the way infants are fed and growth monitored in the NICU. These issues will be reviewed, in the process underline the key roles that audit, standardised feeding protocol, individualised nutritional care and a nutritional support team play in improving outcome in these high-risk infants.

Pregnancy outcomes following the administration of high doses of dexamethasone in early pregnancy

OBJECTIVE

In the present study, we aimed to evaluate the effects of high doses of dexamethasone (DEX) in early pregnancy on pregnancy outcomes.

METHODS

Pregnant BALB/c mice were treated with high-dose DEX in the experimental group or saline in the control group on gestational days (GDs) 0.5 to 4.5. Pregnant mice were sacrificed on GDs 7.5, 13.5, or 18.5 and their peripheral blood, placentas, fetuses, and uterine tissue were collected. Decidual and placenta cell supernatants were examined to evaluate the effect of DEX on the proliferation of mononuclear cells, the quantity of uterine macrophages and uterine natural killer (uNK) cells, and levels of progesterone and 17β-estradiol, as determined by an 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay, immunohistochemistry, and enzyme-linked immunosorbent assay, respectively. We also were measured fetal and placental growth parameters on GD 18.5.

RESULTS

We found that high doses of DEX were associated with an increased abortion rate, enhancement of the immunosuppressive effect of the decidua, alterations in placental growth parameters, decreased progesterone and 17β-estradiol levels, and a reduced frequency of macrophages and uNK cells.

CONCLUSION

Our data suggest that the high-dose administration of DEX during early pregnancy negatively affected pregnancy outcomes.

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

Extremely poor growth of some individuals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles ( Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were sampled. Laboratory testing included postmortem; histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups); hematology; serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron); bacterial culture of liver and spleen (2005 only); viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only); and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant ( P < .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).

Acute Antiapoptotic Effects of Hydrocortisone in the Hippocampus of Neonatal Rats

Natural glucocorticoid hydrocortisone was suggested as a potent substitution for dexamethasone in the treatment of bronchopulmonary dysplasia in neonates. The aim of this study was to investigate whether hydrocortisone is able to affect the expression of apoptotic genes and the intensity of naturally occurring cell death in the developing rat hippocampus. Hormone treatment decreased procaspase-3 and active caspase-3 levels as well as DNA fragmentation intensity in the hippocampal formation of one-week-old rats in 6 h after injection. These changes were accompanied by an upregulation of antiapoptotic protein Bcl-XL, while expression of proapoptotic protein Bax remained unchanged. The action of hydrocortisone was glucocorticoid receptor-independent, as the selective glucocorticoid receptor agonist dexamethasone did not affect either apoptotic protein levels or DNA fragmentation intensity in the hippocampal region. The data are the first evidences for in vivo antiapoptotic effects of hydrocortisone in the developing hippocampus.

The role of cortisol in chronic binge alcohol-induced cerebellar injury: Ovine model

Women who drink alcohol during pregnancy are at high risk of giving birth to children with neurodevelopmental disorders. Previous reports from our laboratory have shown that third trimester equivalent binge alcohol exposure at a dose of 1.75 g/kg/day results in significant fetal cerebellar Purkinje cell loss in fetal sheep and that both maternal and fetal adrenocorticotropin (ACTH) and cortisol levels are elevated in response to alcohol treatment. In this study, we hypothesized that repeated elevations in cortisol from chronic binge alcohol are responsible at least in part for fetal neuronal deficits. Animals were divided into four treatment groups: normal control, pair-fed saline control, alcohol and cortisol. The magnitude of elevation in cortisol in response to alcohol was mimicked in the cortisol group by infusing pregnant ewes with hydrocortisone for 6 h on each day of the experiment, and administering saline during the first hour in lieu of alcohol. The experiment was conducted on three consecutive days followed by four days without treatment beginning on gestational day (GD) 109 until GD 132. Peak maternal blood alcohol concentration in the alcohol group was 239 ± 7 mg/dl. The fetal brains were collected and processed for stereological cell counting on GD 133. The estimated total number of fetal cerebellar Purkinje cells, the reference volume and the Purkinje cell density were not altered in response to glucocorticoid infusion in the absence of alcohol. These results suggest that glucocorticoids independently during the third trimester equivalent may not produce fetal cerebellar Purkinje cell loss. However, the elevations in cortisol along with other changes induced by alcohol could together lead to brain injury seen in the fetal alcohol spectrum disorders.

Gestational and postpartum corticosterone exposure to the dam affects behavioral and endocrine outcome of the offspring in a sexually-dimorphic manner

Exposure to high levels of glucocorticoids in utero and during the postpartum period has a detrimental effect on brain development. We created an animal model of postpartum stress/depression based on administering high levels of corticosterone (CORT) to the dams during the postpartum period which caused behavioral changes and reduced hippocampal cell proliferation in the offspring. As the consequences of early exposure to glucocorticoids may depend on the dose and the developmental stage of the offspring, the present study was conducted to investigate the effects of low (10 mg/kg) or high levels of CORT (40 mg/kg) given to dams either during gestation, postpartum or across both gestation and postpartum on the outcome of the offspring. Male and female offspring were weighed throughout the experiment, tested in a series of behavioral tests (forced swim test, open field, elevated plus maze) and basal and restraint stress CORT levels were examined in adolescence or young adulthood. Results show that maternal CORT exposure, regardless of when administered, significantly attenuated body weight gain until adulthood in the offspring. Offspring exposed to low maternal CORT, but not high maternal CORT, during the postpartum had higher basal levels of CORT as young adults. Further, male and female offspring of dams exposed to high maternal CORT in utero showed more depressive-like behavior in the forced swim test, while males of dams exposed to high maternal CORT postpartum exhibited more anxiety-like behavior in the elevated plus maze. Taken together, maternal glucocorticoid exposure have long lasting effects on male and female offspring's behavioral and neuroendocrine measures in adolescence and adulthood depending on the time of exposure to glucocorticoids. This article is part of a Special Issue entitled 'Anxiety and Depression'.

Responses of glial cells to stress and glucocorticoids

A growing body of evidence suggests that glial cells are involved in practically all aspects of neural function. Glial cells regulate the homeostasis of the brain, influence the development of the nervous system, modulate synaptic activity, and carry out the immune response inside the brain. In addition, they play an important role in the restoration of the nervous system after damage, and they also participate in various neurodegenerative disorders. In a similar way, the importance of stress and glucocorticoids (GCs) on brain function is being increasingly recognized. Within the brain, stress hormones target both neurons and glial cells. Through their actions on these cells, glucocorticoids exert organizational functions on various processes of the developing brain and contribute to neuronal plasticity in the adult brain. Moreover, stress and glucocorticoids have become especially attractive in the study of a number of neurodegenerative disorders. However, studies on the mechanisms behind glucocorticoid-induced regulation of brain function have been classically focused on their effects on neurons. In this review, we start by describing the main functions of glial cells and then proceed to present data highlighting the effects of stress and GCs on brain function. We conclude the review by presenting recent evidence linking stress and glucocorticoids to glial cell function.

The angiogenic factor midkine is regulated by dexamethasone and retinoic acid during alveolarization and in alveolar epithelial cells

Background

A precise balance exists between the actions of endogenous glucocorticoids (GC) and retinoids to promote normal lung development, in particular during alveolarization. The mechanisms controlling this balance are largely unknown, but recent evidence suggests that midkine (MK), a retinoic acid-regulated, pro-angiogenic growth factor, may function as a critical regulator. The purpose of this study was to examine regulation of MK by GC and RA during postnatal alveolar formation in rats.

Methods

Newborn rats were treated with dexamethasone (DEX) and/or all-trans-retinoic acid (RA) during the first two weeks of life. Lung morphology was assessed by light microscopy and radial alveolar counts. MK mRNA and protein expression in response to different treatment were determined by Northern and Western blots. In addition, MK protein expression in cultured human alveolar type 2-like cells treated with DEX and RA was also determined.

Results

Lung histology confirmed that DEX treatment inhibited and RA treatment stimulated alveolar formation, whereas concurrent administration of RA with DEX prevented the DEX effects. During normal development, MK expression was maximal during the period of alveolarization from postnatal day 5 (PN5) to PN15. DEX treatment of rat pups decreased, and RA treatment increased lung MK expression, whereas concurrent DEX+RA treatment prevented the DEX-induced decrease in MK expression. Using human alveolar type 2 (AT2)-like cells differentiated in culture, we confirmed that DEX and cAMP decreased, and RA increased MK expression.

Conclusion

We conclude that MK is expressed by AT2 cells, and is differentially regulated by corticosteroid and retinoid treatment in a manner consistent with hormonal effects on alveolarization during postnatal lung development.

Mothers produce less aggressive sons with altered immunity when there is a threat of disease during pregnancy

Maternal experience before and during pregnancy is known to play a key role in offspring development. However, the influence of social cues about disease in the maternal environment has not been explored. We indirectly exposed pregnant mice to infected neighbours by housing them next to non-contagious conspecifics infected with Babesia microti. We examined the effect of this indirect immunological exposure on both the females and their adult offspring. Exposed females had higher levels of serum corticosterone and increased kidney growth compared with those with uninfected neighbours. These exposed females subsequently produced offspring that as adults showed an accelerated immune response to B. microti and less aggression in social groups. We suggest that ambient information regarding disease is used adaptively to maximize offspring survival and reproductive success in a challenging environment. Our results shed light on the impact of social information and maternal effects on life histories, and have important consequences for our understanding of epidemiology and individual disease susceptibility in humans and other animals. They also lead us to question the suitability of some laboratory housing conditions during experimental procedures, which may impact negatively upon both animal welfare and the validity of animal science.

Hypothalamic-pituitary-adrenal axis activity of newborn mice rapidly desensitizes to repeated maternal absence but becomes highly responsive to novelty

In CD1 mice we investigated the hypothalamic-pituitary-adrenal (HPA) axis response to maternal separation for 8 h daily from postnatal d 3 to 5. At d 3 a slow separation-induced corticosterone response developed that peaked after 8 h, and the pups became responsive to stressors. On the second and third day, the response to 8 h separation rapidly attenuated, whereas the response to novelty did not, a pattern reflected by the hypothalamic c-fos mRNA response. If maternal separation and exposure to novelty were combined, then after the third such daily exposure, the sensitivity to the stressor was further enhanced. Meanwhile, basal corticosterone and ACTH levels were persistently suppressed 16 h after pups were reunited with their mothers. To explain the HPA axis desensitization after repeated separation, we found that circulating ghrelin levels increased and glucose levels decreased after all periods of maternal separation, ruling out a role of altered metabolism. Glucocorticoid feedback was not involved either because a glucocorticoid receptor antagonist amplified the corticosterone response after the first but became ineffective after the third separation. In contrast, a mineralocorticoid receptor antagonist decreased and increased corticosterone levels after the first and third period of separation, respectively. In conclusion, the newborn's HPA axis readily desensitizes to repeated daily maternal separation, but continues to respond to novelty in a manner influenced by a central mineralocorticoid receptor- rather than glucocorticoid receptor-mediated mechanism.

Neonatal endotoxin exposure modifies the acoustic startle response and circulating levels of corticosterone in the adult rat but only following acute stress

A variety of early life stressors have consistently been implicated in the development of psychopathology in adulthood. The current study investigates a rarely considered form of early life stress, bacterial infection, for its ability to induce psychopathology-like symptoms in adult rat. Specifically, neonatal rats were exposed to a simulated bacterial infection. In adulthood the acoustic startle response of these animals was evaluated both prior to and following exposure to restraint stress. Our results indicate that animals neonatally exposed to infection exhibit a significantly exaggerated acoustic startle response but only following exposure to stress. Additionally, we observed that adult animals neonatally exposed to infection, exhibited increased production of circulating corticosterone following stress, indicating potentiated hypothalamic pituitary adrenal axis activity as well as altered novelty seeking behaviour and locomotor activity. These results extend upon existing pre-clinical findings that indicate certain stressful early life events can predispose the adult animal to exhibit abnormal behaviour in adulthood.

Habituation to humans affects yolk steroid levels and offspring phenotype in quail

In the field as well as in the laboratory, human-generated stress responses are reduced in adult animals previously habituated to humans in comparison to non-habituated individuals. In birds, yolk steroid levels vary with maternal environment and condition. We tested the hypothesis that the experience of female birds with humans could affect yolk steroids levels and offspring phenotype. Two groups of Japanese quail, one habituated to humans (H) and a second non-habituated (NH), were exposed daily to brief human disturbances. We analysed egg quality, offspring growth, and offspring emotional reactivity. NH females produced eggs with less androgens (testosterone and androstenedione) and more immunoreactive progesterone compared to birds habituated to humans. NH females produced eggs with less yolk, heavier shell and chicks hatching later and being smaller as compared to habituated individuals. A lower emotional reactivity was found in young of NH females compared to young of H females. Thus, human disturbance of the mother triggered different effects on chick phenotype depending on previous experience of mother birds with humans. In addition, we describe for the first time the influence of environmental stimuli on yolk immunoreactive progesterone levels. Our results show that a relatively minor difference in behavioral habituation may have substantial effects on eggs and offspring. This has obvious implications for keeping and handling laboratory animals, for conservation biology and for animal welfare.

Effects of perinatal oxycodone exposure on the response to CRH in late adolescent rats

We hypothesized that prenatal oxycodone exposure suppresses the Hypothalamic-Pituitary-Adrenal (HPA) response to stress in late adolescence. Dark Agouti rats were given either intravenous oxycodone or vehicle (controls, CON) daily from gestation day 8 until postnatal day (PD) 5. At PD 45, the male and female offspring received intravenously either ovine corticotropin releasing hormone (CRH) or saline. Plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels were determined before, and 15, 30, and 60 min after injection. Prenatal oxycodone had no effect on baseline ACTH values; CRH elicited a greater ACTH response than saline. In males, prenatal oxycodone delayed and enhanced the peak ACTH response to CRH, but had no effect in females. The CORT response to CRH was not different between oxycodone and CON; however mean CORT levels in females were significantly higher than those in males at baseline and after stimulation. These results demonstrate that prenatal oxycodone increases pituitary response to CRH in late adolescent male rats, but not in females. The absence of an enhanced adrenal response in oxycodone-exposed males suggests either desensitization or maximal adrenal response to a high CRH dose. The mechanisms of postnatal sex-specific HPA dysregulation following prenatal oxycodone remain to be elucidated.

Follow-up of a randomized, placebo-controlled trial of dexamethasone to decrease the duration of ventilator dependency in very low birth weight infants: neurodevelopmental outcomes at 4 to 11 years of age

OBJECTIVE

High doses of dexamethasone reduce the risk of chronic lung disease among premature infants but may increase the risk of developmental impairments. The objective of this study was to compare developmental outcomes beyond infancy for children who, as neonates, participated in a randomized trial of dexamethasone.

PATIENTS AND METHODS

One hundred eighteen children with birth weights <1500 g were randomly assigned at 15 to 25 days of life to a 42-day tapering course of dexamethasone or placebo. All 95 survivors were assessed by using standardized measures of developmental outcome at least once at or beyond 1 year of age, and 84 were examined at 4 to 11 years. For this follow-up study, the outcome of primary interest was death or major neurodevelopmental impairment, which was defined as cerebral palsy, cognitive impairment, or blindness.

RESULTS

On the basis of each child's most recent follow-up, the rates of major neurodevelopmental impairments were 40% for the dexamethasone group and 20% for the placebo group. The higher impairment rate for the dexamethasone group was mainly attributed to a higher prevalence of cerebral palsy. Rates of the composite outcome of death or major neurodevelopmental impairment were 47% and 41%, respectively.

CONCLUSION

A 42-day tapering course of dexamethasone, which was shown previously to decrease the risk of chronic lung disease in very low birth weight infants, does not increase the risk of the composite outcome of death or major neurodevelopmental impairment.

Kinetics of betamethasone and fetal cardiovascular adverse effects in pregnant sheep after different doses

OBJECTIVE

To study the pharmacokinetics of different betamethasone doses and preparations used to enhance fetal lung maturation in the maternal and fetal circulation of sheep and the adverse effects on fetal blood pressure.

METHODS

Doses of 170 (n = 6) and 110 microg/kg (n = 6) betamethasone phosphate equivalent to 12 or 8 mg, respectively, administered to a 70 kg pregnant woman or 170 microg/kg (n = 6) of a depot formulation (50% betamethasone phosphate and 50% betamethasone acetate) were injected intramuscularly to chronically instrumented pregnant sheep.

RESULTS

Both betamethasone preparations produced highest maternal concentrations after 15 min followed by an exponential decline with a t(1/2) of about 3 hours. The drug fell below the limit of detection at 8 to 12 hours. Betamethasone was first detectable in the fetal circulation at 1 hour, peaked at 3 hours, and decreased below the limit of detection at 8 hours independently of the dose or preparation. Maternal and fetal betamethasone concentrations achieved with the phosphate and acetate formulation were one half of those obtained with betamethasone phosphate, suggesting that very little betamethasone is released from the acetate within the first 8 hours when the effect on lung maturation is needed. Betamethasone led to a maximal increase of mean fetal blood pressure from 42+/-1 to 51+/-1 mm Hg (P < .05) and did not differ between the doses and preparations, although plasma concentrations showed a clear dose-concentration relationship.

CONCLUSION

The doses of betamethasone used in obstetrics are supramaximal in terms of cardiovascular effects in sheep. Risk-benefit studies are needed to find the effective steroid dose with the least adverse effects.

Administration of antisense oligonucleotide against pro-opiomelanocortin prevents enduring hormonal alterations induced by neonatal handling in male mice

Early life events have been implicated in the programming of adult chronic diseases. Several investigations suggest that the role of early environment in influencing development mainly involves the hypothalamic-pituitary-adrenal axis. Therefore, we examined whether 1) daily neonatal handling, applied from birth to weaning induces HPA hormones alterations in mice lasting up to the adult age; and 2) if the administration of an antisense oligodeoxynucleotide versus pro-opiomelanocortin (As-POMC) prevents hormonal alterations observed in previously handled mice (Handled). In the adult phase (90 days), Handled are overweight and have higher basal plasma immuno-reactive (ir)-corticosterone and adrenocorticotropin (ir-ACTH), and higher pituitary ir-ACTH; while they have lower hypothalamic ir-ACTH and corticotropin-releasing hormone (ir-CRH) in comparison with the non-handled mice. As-POMC (0.05-0.1 nmol/g body weight per day) administered during the same period dose-dependently prevents the increase in body weight, in plasma ir-corticosterone, ir-ACTH, and pituitary ir-ACTH, also preventing the decrease in hypothalamic ir-CRH and ir-ACTH; while the mismatch oligonucleotide is nearly inactive. This data indicates that pharmacological treatment in neonatal life may have enduring effects, reducing the alterations in hormonal homeostatic programming mechanisms induced by early repeated handling.

High post-partum levels of corticosterone given to dams influence postnatal hippocampal cell proliferation and behavior of offspring: A model of post-partum stress and possible depression

Post-partum stress and depression (PPD) have a significant effect on child development and behavior. Depression is associated with hypercortisolism in humans, and the fluctuating levels of hormones, including corticosterone, during pregnancy and the post-partum, may contribute to PPD. The present study was developed to investigate the effects of high-level corticosterone (CORT) post-partum in the mother on postnatal neurogenesis and behavior in the offspring. Sprague-Dawley dams were treated with either CORT (40 mg/kg) or sesame oil injections daily for 26 days beginning the day after giving birth. Dams were tested in the forced swim test (FST) and in the open field test (OFT) on days 24-26 post-partum. Results showed that the dams exposed to CORT expressed "depressive-like" behavior compared to controls, with decreased struggling behavior and increased immobility in the FST. To investigate the effects of treatment on hippocampal postnatal cell proliferation and survival in the offspring, males and females from treated dams were injected with BrdU (50 mg/kg) on postnatal day 21 and perfused either 24 h (cell proliferation) or 21 days (cell survival) later. Furthermore, male and female offspring from each litter were tested in adulthood on various behavioral tests, including the forced swim test, open field test, resistance to capture test and elevated plus maze. Intriguingly, male, but not female, offspring of CORT-treated dams exhibited decreased postnatal cell proliferation in the dentate gyrus. Both male and female offspring of CORT-treated dams showed higher resistance to capture and greater locomotor activity as assessed in the open field test. As high levels of CORT may be a characteristic of stress and/or depression, these findings support a model of 'CORT-induced' post-partum stress and possibly depression and demonstrate that the offspring of affected dams can exhibit changes in postnatal neurogenesis and behavior in adulthood.

Individual differences in glucose homeostasis: do our early life interactions with bacteria matter?

Exposure to endotoxin during the neonatal period in the rat has been shown to alter the development of the hypothalamic-pituitary-adrenal axis, inducing hyper-responsivity and increased glucocorticoid production in later-life. Glucocorticoids are known to have major metabolic effects, therefore, early life endotoxin exposure may have potentially serious consequences for metabolic homeostasis in the exposed animal. The aims of this study were therefore to assess the effect of neonatal bacterial endotoxin exposure on subsequent glucose homeostasis, insulin action and corticosterone production from puberty through to senescence. Male Fischer-344 rat pups were treated with bacterial endotoxin (0.05 mg/kg Salmonella enteritidis i.p.) or vehicle (sterile pyrogen free saline) on days 3 and 5 postnatally. Insulin and glucose levels were assessed before and during and intraperitoneal glucose tolerance test (IPGTT) together with body mass on postnatal days 40, 80, and 400. In addition, circulating levels of corticosterone were measured at 0, 30, and 90 min following a 30-min restraint challenge at these ages. Neonatal endotoxin challenge did not alter fasting plasma glucose or insulin, but impaired glucose tolerance at puberty (p<.05), improved glucose tolerance in adulthood (p<.05) and had no effect at senescence. During the IPGTT insulin was reduced at all ages (p<.05) following neonatal endotoxin challenge, but insulin sensitivity was unaltered, except for an increase in adulthood (p<.05), which is consistent with the observed improvement in glucose tolerance at this age. Neonatal endotoxin challenge reduced body mass during puberty and senescence (p<.05) but did not alter basal or stressed plasma corticosterone levels at any of the three developmental time points examined. These findings suggest that variations in an individual's early life bacterial environment may contribute to differences in glucose homeostasis, insulin action and disease susceptibility later in life.

Exogenous antenatal glucocorticoid treatment reduces susceptibility for hippocampal kindled and maximal electroconvulsive seizures in infant rats

Dexamethasone (DEX) and betamethasone (BETA) are synthetic glucocorticoids used clinically to reduce morbidity and mortality in infants at risk of premature birth. While their main role is to facilitate lung development, their effect on the developing nervous system and seizure susceptibility is unclear. The present study tested the hypothesis that antenatal DEX or BETA treatment would alter seizure thresholds and spread of epileptiform activity in the brains of infant offspring. Pregnant dams received once daily injections with DEX, BETA, or vehicle on gestation days 15 to 18. Physical appearance, litter size, and weight of the pups were assessed postnatally. Seizure thresholds were determined on postnatal day 14 using electroconvulsive shock delivered through ear clips (i.e., generalized seizure) or kindling stimulation of the left hippocampus through indwelling electrodes (i.e., partial seizure). The rate of acquisition of kindled seizures was determined on postnatal days 14 and 15. Pups from dams treated with DEX and BETA were growth restricted. Antenatal BETA treatment increased seizure threshold for both models. Antenatal DEX treatment increased kindling threshold, but not electroconvulsive shock threshold. Kindling rate was unaffected by either antenatal treatment. In summary, repeated glucocorticoid treatments had adverse effects on weight, skin and litter size, raised seizure thresholds, and reduced seizure vulnerability. Although these effects are seemingly desirable with respect to seizure susceptibility, they suggest that the functional organization of the nervous system is altered with antenatal synthetic glucocorticoid treatment.

Development of neurotransmitter systems during critical periods

Neurotransmitters are released from neurons and mediate neuronal communication. Neuromodulators can also be released from other cells and influence the neuronal signaling. Both neurotransmitters and neuromodulators play an important role in the shaping and the wiring of the nervous system possibly during critical windows of the development. Monoamines are expressed in the very early embryo, at which stage the notochord already contains high noradrenaline levels. Purines and neuropeptides are probably also expressed at an early stage, in a similar way as they occur during early phylogenesis. The levels of most neurotransmitters and neuromodulators increase concomitantly with synapse formation. Some of them surge during the perinatal period (such as glutamate, catecholamines, and some neuropeptides) and then level off. The interesting question is to what extent the expression of neuroactive agents is related to the functional state of the fetus and the newborn. Monoamines are expressed in the very early embryo, at which stage the notochord already contains high noradrenaline levels. They may have an important role for neurotransmission in the fetus. In the adult mammal, the fast switching excitatory amino acids dominate. However, they also seem to be important for the wiring of the brain and the plasticity before birth. NMDA receptors that are supposed to mediate these effects dominate and are then substituted by AMPA receptors. The main inhibitory amino acids gamma-aminobutyric acid (GABA) and glycine are excitatory in the developing brain by depolarizing developing neurons that have high Cl- concentrations. This seems to be of major importance for the wiring of neuronal circuits. Prenatal or neonatal stress, for example, hypoxia, can affect the programming of neurotransmitter and receptor expression, which can lead to long-term behavioral effects.

Is sexual dimorphism affected by the combined action of prenatal stress and sex ratio?

During embryonic development, offspring are exposed to hormones of both maternal and sibling origin. Maternal stress increases offspring exposure to corticosterone, and, in polytocous animals, the sex ratio or intrauterine position can influence the levels of androgens and estrogens experienced by the offspring. Such hormone exposure has the potential to influence many important morphological and behavioural aspects of offspring, in particular sexually dimorphic traits. Although well known in rodents, the impact of prenatal hormone exposure in other vertebrates is poorly documented. We experimentally investigated the relationship between maternal stress, population density, sex ratio (a surrogate for the degree of exposure to steroids produced by siblings), and sexual dimorphism in a viviparous lizard, Lacerta vivipara. Our results show that prenatal sex ratios have consequences for sexually dimorphic morphology (ventral scale count) in both sexes, but with no effect of maternal stress or any interaction between the two. Embryonic steroid exposure can potentially be an important factor in generating individual variation in natural populations of viviparous animals.

Systemic adrenocorticotropic hormone administration down-regulates the expression of corticotropin-releasing hormone (CRH) and CRH-binding protein in infant rat hippocampus

Systemic adrenocorticotropic hormone (ACTH) administration is a first-line therapy for the treatment of infantile spasms, an age-specific seizure disorder of infancy. It is proposed that exogenous ACTH acts via negative feedback to suppress the synthesis of corticotropin-releasing hormone (CRH), a possible endogenous convulsant in infant brain tissue. The aim of this study was to determine whether systemic ACTH treatment in infant rats down-regulates the hippocampal CRH system, including CRH, CRH-binding protein (CRH-BP), and CRH receptors (CRH-R1 and CRH-R2). Daily i.p. injection of ACTH for 7 consecutive days (postnatal days 3-9) elevated serum corticosterone levels 20-fold measured on postnatal day 10, indicating systemic absorption and circulation of the ACTH. Semiquantitative reverse transcriptase-PCR demonstrated that both CRH and CRH-BP mRNA obtained from the hippocampi of ACTH-injected infant rats was significantly depressed relative to saline-injected animals. Comparable reductions in both CRH and CRH-BP synthesis were further demonstrated with radioimmunoassay. In contrast, neither CRH-R1 nor CRH-R2 mRNA was altered by ACTH treatment, relative to saline-injected rats. This latter finding was confirmed electrophysiologically by measuring the enhancement of hippocampal population spikes by exogenous CRH, also showing no differences between ACTH- and saline-injected rats. The results of this study support the proposal that systemic ACTH treatment down-regulates CRH expression in infant brain, perhaps contributing to the therapeutic efficacy observed during treatment of infantile spasms.

Psychosocial effects of intensive care on infants and families after discharge

The neonatal intensive care environment exposes the developing immature newborn to many sources of stress and pain at a time when the infant is developmentally least able to cope with it. Animal and human evidence suggest that effects of stress, mediated through permanent changes in the brain and neuroendocrine responses, may result in changes in behaviour and information processing, which persist throughout childhood. These changes impact on the dynamics of the mother infant dyad and infant learning. Interactional styles arising in the newborn period tend to persist throughout childhood but may be amenable to intervention focusing on maternal recognition of infant cues, social stimulation of the infant, and family integration. Developmental care may promote better family, infant and child outcomes by both reducing neonatal stress and its neurobiological sequelae, and fostering an appropriate interactional relationship between mother and infant.

Corticosteroids in the prevention and management of bronchopulmonary dysplasia

Corticosteroids were first prescribed for preterm neonates to treat respiratory distress syndrome, but they were found to have no beneficial effect in this disorder. About 20 years ago, dexamethasone was first used to treat infants with bronchopulmonary dysplasia who were ventilator dependent after the age of 3 weeks. There were short-term benefits, with an improvement in lung function and a facilitation of endotracheal extubation. During the 1990s, corticosteroid treatment, mainly with dexamethasone in relatively high doses, became very common in neonatal intensive care units. Towards the end of the decade, however, follow-up studies provided evidence of abnormal neurodevelopment, especially in infants treated early (<4 days) with dexamethasone. The precise cause of these neurodevelopmental problems is unclear, but until further evidence has been obtained, the early use of dexamethasone cannot be recommended for preterm infants. This review attempts to provide evidence-based guidelines for postnatal steroid therapy in the management of chronic lung disease.

Effects of neonatal high-dose short-term glucocorticoid treatment on the lung: a morphologic and morphometric study in the rat

Glucocorticoids are often applied in neonatology and perinatology to fight the problems of respiratory distress and chronic lung disease. There are, however, many controversies regarding the adverse side effects and long-term clinical benefits of this therapeutic approach. In rats, glucocorticoids are known to seriously impair the formation of alveoli when applied during the first two postnatal weeks even at very low dosage. The current study investigates short-term and long-term glucocorticoid effects on the rat lung by means of morphologic and morphometric observations at light and electron microscopic levels. Application of a high-dosage protocol for only few days resulted in a marked acceleration of lung development with a precocious microvascular maturation resulting in single capillary network septa in the first 4 postnatal days. By postnatal d 10, the lung morphologic phenotype showed a step back in the maturational state, with an increased number of septa with double capillary layer, followed by an exceptional second round of the alveolarization process. As a result of this process, there was an almost complete recovery in the parenchymal lung structure by postnatal d 36, and by d 60, there were virtually no qualitative or quantitative differences between experimental and control rats. These findings indicate that both dosage and duration of glucocorticoid therapy in the early postnatal period are very critical with respect to lung development and maturation and that a careful therapeutic strategy can minimize late sequelae of treatment.

[The Europe against immature lung (EURAIL) project. Strategies for the prevention and treatment of lung immaturity in neonates]

OBJECTIVE

To determine clinical practice variability in the prevention and postnatal treatment of lung immaturity in Spain.

PATIENTS AND METHODS

Cross-sectional study within a larger study in 13 European countries. Data were obtained from the medical records of all very low birth weight (VLBW) infants born in participating centers, without other instrumentation.

RESULTS

A questionnaire was sent to 213 centers. Seventy-two (34 %) responded, with 162,157 births (40 % of total births in 1999). Eight percent of infants were of low birth weight, 1.2 % (2,015) of very low birth weight and 0.45 % were of extremely low birth weight. A total of 52.2 % of VLBW infants received at least one dose of prenatal steroids, 28.8 % received a full course and 9.3 % received more than one cycle. All centres used surfactant and 76.8 % had a written protocol. Forty-one percent of VLBW infants were intubated, 47.6 % required mechanical ventilation for more than 6 hours, and 5 % underwent continuous positive airway pressure. A total of 80.4 % used postnatal steroids, half of them for chronic lung disease prevention, and 83.4 % used steroids to treat this disease. Steroids were most frequently indicated at 7-14 days of life for 3-9 days. The most important causes of neonatal morbidity were chronic lung disease in 14 %, ductus arteriosus in 16.7 %, intraventricular hemorrhage in 8.5 %, and necrotizing enterocolitis in 7.3 %.

CONCLUSIONS

Prenatal exposure to steroids was low. Repeat cycles and postnatal steroid use to prevent chronic lung disease was high. Recent scientific evidence on the use of pre- and postnatal steroids should be more widely disseminated.

Cognitive and behavioral deficits in premature graduates of intensive care

A substantial number of VLBW graduates of intensive care develop cognitive and behavioral problems, even in the absence of neuroimaging abnormalities. Although this article has highlighted the potential, important, contributing role of medical and stressful, neonatal, environmental conditions to the development of these deficits, it is not all-encompassing, and there are additional prenatal (ie, in utero stress, drug exposure) and neonatal (ie, infectious) contributing factors. The long-term, outcome data presented in this article are pertinent to the more mature, VLBW infant, and it remains unclear and critically important to delineate the long-term, neurobehavioral outcome of those extremely low birth-weight survivors born at the cutting limit of viability.

A three year follow up of preterm infants after moderately early treatment with dexamethasone

OBJECTIVE

To assess the effect of moderately early postnatal dexamethasone treatment on growth and neurodevelopmental outcome in preterm infants.

METHODS

Thirty preterm infants enrolled in a randomised clinical trial to investigate the effectiveness of moderately early dexamethasone administration in the treatment of chronic lung disease were routinely followed up. Fifteen babies received a total dose of 4.75 mg/kg over 14 days from the 10th day of life, and 15 babies were untreated. Five infants in each group received open label steroids to facilitate extubation later in their clinical course. Growth and neurodevelopmental outcome are reported.

RESULTS

The mean body weight, height, and head circumference as well as the number of babies with anthropometric measurements within normal range were similar in treated and untreated babies. There was no significant difference between treated and control groups with respect to incidence of cerebral palsy, major neurosensory impairment, mean intelligence quotient scores, and behavioural abnormalities.

CONCLUSIONS

Postnatal dexamethasone treatment with the schedule used in this study did not impair growth and neurodevelopmental outcome in preterm infants. Data from larger trials have raised major concern that postnatal steroid treatment may increase neurodevelopmental impairment. The full extent of the risk will only be known when more trials have reported follow up data.