The effects of prenatal dexamethasone exposure and fructose challenge on pituitary-adrenocortical activity and anxiety-like behavior in female offspring

Effects of Prenatal Dexamethasone Treatment and Post-Weaning Moderate Fructose Intake on Synaptic Plasticity and Behavior in Adult Male Wistar Rat Offspring

Early-life glucocorticoid overexposure induces diverse neurodevelopmental outcomes regarding stress reactivity and cognition. Increased fructose consumption has also been associated with alterations in cognitive capacity and behavior. The present study investigated the effects of prenatal dexamethasone exposure on synaptic plasticity, locomotion, anxiety, and recognition memory in adult male Wistar rat offspring, and whether these effects are potentiated by postnatal fructose consumption. Pregnant female rats were treated with dexamethasone during late gestation and male offspring were supplemented with a moderate dose of fructose. Recognition memory, locomotion, and anxiety-like behavior were assessed using a novel object recognition test, open-field test, and elevated plus maze, respectively. Hippocampal synaptic plasticity was estimated by the levels of growth-associated protein 43 (GAP-43), synaptophysin, postsynaptic density protein 95, calcium/calmodulin-dependent kinase IIα, and their activating phosphorylations. Additionally, protein levels of the glucocorticoid receptor (GR) and its transcriptionally active phosphorylated form were evaluated. Prenatal dexamethasone treatment induced an anxiolytic-like effect, stimulation of exploratory behavior, and novelty preference associated with an increase in GR and GAP-43 protein levels in the hippocampus. Fructose overconsumption after weaning did not modify the effects of prenatal glucocorticoid exposure. Applied prenatal dexamethasone treatment may induce changes in reactions to novel situations in male Wistar rats.

Multi-organ developmental toxicity and its characteristics in fetal mice induced by dexamethasone at different doses, stages, and courses during pregnancy

Dexamethasone is widely used in pregnant women at risk of preterm birth to reduce the occurrence of neonatal respiratory distress syndrome and subsequently reduce neonatal mortality. Studies have suggested that dexamethasone has developmental toxicity, but there is a notable absence of systematic investigations about its characteristics. In this study, we examined the effects of prenatal dexamethasone exposure (PDE) on mother/fetal mice at different doses (0.2, 0.4, or 0.8 mg/kg b.i.d), stages (gestational day 14-15 or 16-17) and courses (single- or double-course) based on the clinical practice. Results showed that PDE increased intrauterine growth retardation rate, and disordered the serum glucose, lipid and cholesterol metabolic phenotypes, and sex hormone level of mother/fetal mice. PDE was further discovered to interfere with the development of fetal lung, hippocampus and bone, inhibits steroid synthesis in adrenal and testis, and promotes steroid synthesis in the ovary and lipid synthesis in the liver, with significant effects observed at high dose, early stage and double course. The order of severity might be: ovary > lung > hippocampus/bone > others. Correlation analysis revealed that the decreased serum corticosterone and insulin-like growth factor 1 (IGF1) levels were closely related to PDE-induced low birth weight and abnormal multi-organ development in offspring. In conclusion, this study systematically confirmed PDE-induced multi-organ developmental toxicity, elucidated its characteristics, and proposed the potential "glucocorticoid (GC)-IGF1" axis programming mechanism. This research provided an experimental foundation for a comprehensive understanding of the effect and characteristics of dexamethasone on fetal multi-organ development, thereby guiding the application of "precision medicine" during pregnancy.

Antenatal Dexamethasone Treatment Induces Sex-dependent Upregulation of NTPDase1/CD39 and Ecto-5'-nucleotidase/CD73 in the Rat Fetal Brain

Dexamethasone (DEX) is frequently used to treat women at risk of preterm delivery, but although indispensable for the completion of organ maturation in the fetus, antenatal DEX treatment may exert adverse sex-dimorphic neurodevelopmental effects. Literature findings implicated oxidative stress in adverse effects of DEX treatment. Purinergic signaling is involved in neurodevelopment and controlled by ectonucleotidases, among which in the brain the most abundant are ectonucleoside triphosphate diphosphohydrolase 1 (NTPDase1/CD39) and ecto-5'-nucleotidase (e5'NT/CD73), which jointly dephosphorylate ATP to adenosine. They are also involved in cell adhesion and migration, processes integral to brain development. Upregulation of CD39 and CD73 after DEX treatment was reported in adult rat hippocampus. We investigated the effects of maternal DEX treatment on CD39 and CD73 expression and enzymatic activity in the rat fetal brain of both sexes, in the context of oxidative status of the brain tissue. Fetuses were obtained at embryonic day (ED) 21, from Wistar rat dams treated with 0.5 mg DEX/kg/day, at ED 16, 17, and 18, and brains were processed and used for further analysis. Sex-specific increase in CD39 and CD73 expression and in the corresponding enzyme activities was induced in the brain of antenatally DEX-treated fetuses, more prominently in males. The oxidative stress induction after antenatal DEX treatment was confirmed in both sexes, although showing a slight bias in males. Due to the involvement of purinergic system in crucial neurodevelopmental processes, future investigations are needed to determine the role of these observed changes in the adverse effects of antenatal DEX treatment.