Prenatal glucocorticoid overexposure causes permanent increases in renal erythropoietin expression and red blood cell mass in the rat offspring

Nucleated red blood cells explain most of the association between DNA methylation and gestational age

Determining if specific cell type(s) are responsible for an association between DNA methylation (DNAm) and a given phenotype is important for understanding the biological mechanisms underlying the association. Our EWAS of gestational age (GA) in 953 newborns from the Norwegian MoBa study identified 13,660 CpGs significantly associated with GA (p_Bonferroni<0.05) after adjustment for cell type composition. When the CellDMC algorithm was applied to explore cell-type specific effects, 2,330 CpGs were significantly associated with GA, mostly in nucleated red blood cells [nRBCs; n = 2,030 (87%)]. Similar patterns were found in another dataset based on a different array and when applying an alternative algorithm to CellDMC called Tensor Composition Analysis (TCA). Our findings point to nRBCs as the main cell type driving the DNAm-GA association, implicating an epigenetic signature of erythropoiesis as a likely mechanism. They also explain the poor correlation observed between epigenetic age clocks for newborns and those for adults.

Effect of prenatal glucocorticoids and thyroid hormones on developmental plasticity of mitochondrial aerobic metabolism, growth and survival: an experimental test in wild great tits

Developmental plasticity is partly mediated by transgenerational effects, including those mediated by the maternal endocrine system. Glucocorticoid and thyroid hormones may play central roles in developmental programming through their action on metabolism and growth. However, the mechanisms by which they affect growth and development remain understudied. One hypothesis is that maternal hormones directly affect the production and availability of energy-carrying molecules (e.g. ATP) by their action on mitochondrial function. To test this hypothesis, we experimentally increased glucocorticoid and thyroid hormones in wild great tit eggs (Parus major) to investigate their impact on offspring mitochondrial aerobic metabolism (measured in blood cells), and subsequent growth and survival. We show that prenatal glucocorticoid supplementation affected offspring cellular aerobic metabolism by decreasing mitochondrial density, maximal mitochondrial respiration and oxidative phosphorylation, while increasing the proportion of the maximum capacity being used under endogenous conditions. Prenatal glucocorticoid supplementation only had mild effects on offspring body mass, size and condition during the rearing period, but led to a sex-specific (females only) decrease in body mass a few months after fledging. Contrary to our expectations, thyroid hormone supplementation did not affect offspring growth or mitochondrial metabolism. Recapture probability as juveniles or adults was not significantly affected by prenatal hormonal treatment. Our results demonstrate that prenatal glucocorticoids can affect post-natal mitochondrial density and aerobic metabolism. The weak effects on growth and apparent survival suggest that nestlings were mostly able to compensate for the transient decrease in mitochondrial aerobic metabolism induced by prenatal glucocorticoids.

Abd-Elhakim Y. Saussurea lappa Ethanolic Extract Attenuates Triamcinolone Acetonide-Induced Pulmonary and Splenic Tissue Damage in Rats via Modulation of Oxidative Stress, Inflammation, and Apoptosis

Background: In this era, worldwide interest has been directed towards using natural antioxidants to guard against drug side effects. Saussurea lappa is a famous medicinal plant with many biologically active compounds. Triamcinolone acetonide (TA) is an extensively used glucocorticoid. Hence, this study explored, for the first time, the possible beneficial effects of S. lappa ethanolic extract on TA-induced oxidative damage in the lung and spleen of rats. Methods: Five experimental groups were used: control group, S. lappa-treated group (600 mg/kg/day, orally), TA-treated group (40 mg/kg/twice/week I/P), S. lappa + TA co-treated group, and S. lappa/TA prophylactic group. Results: TA exposure significantly induced leukocytosis and neutrophilia. In addition, TA significantly reduced the levels of C-reactive protein, interleukin-12, tumor necrosis factor α, and immunoglobulins. Lung Caspase-3 overexpression and splenic CD8⁺ downregulation were also noted in the TA group. TA treatment significantly increased malondialdehyde concentration but reduced superoxide dismutase and glutathione peroxidase activities. S. lappa counteracted the TA oxidative and apoptotic effects. The best results were recorded in the prophylactic group. Conclusions:S. lappa has a remarkable protective effect via its anti-inflammatory, anti-apoptotic, and antioxidant capacity. Thus, it could be a candidate as a natural antioxidant to face glucocorticoid’s harmful side effects.

Blood parameters of preterm neonates: postnatal evolution according to gestational age

INTRODUCTION

The blood count provides qualitative and quantitative essential information on bloodlines. Reference hematologic parameters have been established in children and neonates, but few data are available regarding the premature population during the first month of life. The main objective of this study was to establish normative values for blood parameters for premature infants born between 26 and <37 weeks of gestation, during the first month of life, taking into account gestational and postnatal age and treatments that can impact the threshold values.

METHODS

A single-center retrospective study was conducted based on the clinical and laboratory data of preterm infants born between January 1, 2012 and December 31, 2013 and hospitalized in the intensive care, neonatal, and maternity units of University Hospital of Saint Etienne (France). Data were collected by crossing the PMSI database (date of birth and gestational age), the administrative patient database (IPP), and the pre-analytical laboratory database. Anthropometric and clinical data were extracted for both mother and child. The samples were all made from central or peripheral venous blood. All blood parameters were taken into account.

RESULTS

The degree of prematurity is a factor greatly influencing the values of the blood parameters at birth. All three blood lines increase in proportion to gestational age. We were able to highlight for some blood parameters specific kinetic profiles according to gestational age.

CONCLUSION

Blood parameters of preterm neonates depend on both the degree of prematurity, postnatal age, and perinatal treatments. A good knowledge of these physiological variations may help target transfusion or therapeutic indications in everyday practice.

Chronic restraint stress upregulates erythropoiesis through glucocorticoid stimulation

In response to elevated glucocorticoid levels, erythroid progenitors rapidly expand to produce large numbers of young erythrocytes. Previous work demonstrates hematopoietic changes in rodents exposed to various physical and psychological stressors, however, the effects of chronic psychological stress on erythropoiesis has not be delineated. We employed laboratory, clinical and genomic analyses of a murine model of chronic restraint stress (RST) to examine the influence of psychological stress on erythropoiesis. Mice exposed to RST demonstrated markers of early erythroid expansion involving the glucocorticoid receptor. In addition, these RST-exposed mice had increased numbers of circulating reticulocytes and increased erythropoiesis in primary and secondary erythroid tissues. Mice also showed increases in erythroid progenitor populations and elevated expression of the erythroid transcription factor KLF1 in these cells. Together this work reports some of the first evidence of psychological stress affecting erythroid homeostasis through glucocorticoid stimulation.

Morphometric evaluation of the fetal rat liver after maternal dexamethasone treatment: effect on the maturation of erythroid and megakaryocytic cells

BACKGROUND

During pregnancy, glucocorticoids are frequently used to accelerate fetal lung maturation in preterm delivery. However, prenatal administration of glucocorticoids has been shown to affect organs such as fetal liver, an important hematopoietic organ during fetal development.

OBJECTIVE

The aim of this study was to document the qualitative and quantitative changes in erythroid and megakaryocytic cell populations found in fetal livers as well as the hematology profile in neonates after maternal glucocorticoid treatment in rats.

METHODS

Pregnant female Wistar rats were treated with dexamethasone 21-phosphate from days 13 to 16 of gestation. On the 17th day of pregnancy, the fetuses were collected and their livers processed for light and transmission electron microscopy. Glycol methacrylate-embedded sections were stained with PAS to determine the erythroblast and megakaryocytic cell frequencies. Fetal liver pieces embedded in Spurr resin were analyzed by transmission electron microscopy for morphologic changes. A standard hematology profile was evaluated in neonatal rats.

RESULTS

In the fetuses from treated dams, the total cell number of erythroid cells in livers was significantly reduced compared to control fetuses (P < .001), but erythroblasts did not present ultrastructural abnormalities. The degree of maturation in the megakaryocyte series tended to be increased. In neonates, there were elevated numbers of nucleated RBCs (P = .002), along with a higher HCT and HGB (P = .02). In addition, the platelet concentration was also significantly increased (P < .007).

CONCLUSION

These results suggest that maternal dexamethasone treatment has quantitative effects on erythroid and megakaryocytic cells in fetal liver and the neonatal hematology profile in rats.

In utero glucocorticoid exposure reduces fetal skeletal muscle mass in rats independent of effects on maternal nutrition

Maternal stress and undernutrition can occur together and expose the fetus to high glucocorticoid (GLC) levels during this vulnerable period. To determine the consequences of GLC exposure on fetal skeletal muscle independently of maternal food intake, groups of timed-pregnant Sprague-Dawley rats (n = 7/group) were studied: ad libitum food intake (control, CON); ad libitum food intake with 1 mg dexamethasone/l drinking water from embryonic day (ED)13 to ED21 (DEX); pair-fed (PF) to DEX from ED13 to ED21. On ED22, dams were injected with [(3)H]phenylalanine for measurements of fetal leg muscle and diaphragm fractional protein synthesis rates (FSR). Fetal muscles were analyzed for protein and RNA contents, [(3)H]phenylalanine incorporation, and MuRF1 and atrogin-1 (MAFbx) mRNA expression. Fetal liver tyrosine aminotransferase (TAT) expression was quantified to assess fetal exposure to GLCs. DEX treatment reduced maternal food intake by 13% (P < 0.001) and significantly reduced placental mass relative to CON and PF dams. Liver TAT expression was elevated only in DEX fetuses (P < 0.01). DEX muscle protein masses were 56% and 70% than those of CON (P < 0.01) and PF (P < 0.05) fetuses, respectively; PF muscles were 80% of CON (P < 0.01). Muscle FSR decreased by 35% in DEX fetuses (P < 0.001) but were not different between PF and CON. Only atrogin-1 expression was increased in DEX fetus muscles. We conclude that high maternal GLC levels and inadequate maternal food intake impair fetal skeletal muscle growth, most likely through different mechanisms. When combined, the effects of decreased maternal intake and maternal GLC intake on fetal muscle growth are additive.