SUN-LB56 Steroid and Sex Specific Responses of Neural Stem Cells to Prenatal Dexamethasone versus Betamethasone Administration

Synthetic glucocorticoids (sGCs) are widely administered to pregnant women for their anti-inflammatory, immunosuppressive and organ maturation properties. Worldwide, Dexamethasone (Dex) and Betamethasone (Beta) are the two most commonly administered prenatal sGCs to reduce morbidity and mortality associated with respiratory distress, intraventricular hemorrhage and necrotizing enterocolitis. Preterm administration of sGCs is associated with reduced birthweight and increased risk for hypertension, cardiovascular, metabolic, and neurological problems later in life. Adverse neurological outcome has been shown to depend on the type of sGCs used, the dose, timing of sGCs administration and sex. We have previously shown that the glucocorticoid receptor (GR) is expressed in the developing brain in stem and progenitor cells, neurons and glia from early developmental stages, and that prenatal Dex alters neural stem cell (NSC) biology and the developmental trajectory of the cerebral cortex, hypothalamus and adult behavior. To identify the molecular and cellular basis of the sex and steroid specific responses in the developing brain, we compared the consequence of Dex versus Beta exposure on embryonic cerebral cortical NSC biology. Murine NSC were isolated from the E14.5 cerebral cortex and exposed to 10-7 M Dex, 10-7 M Beta, or Vehicle for 4 or 24 hours and the immediate and long-term impact on transcription, proliferation and neuronal, glial and oligodendrocyte differentiation examined. Affymetrix complete genome transcriptional analyses reveal sex specific responses to Dex versus Beta within 4 hours. At >+/-1.5-fold change 548 genes were differentially regulated by Dex, 452 by Beta and 256 were altered by both Dex and Beta (P < 0.05). Distinct sex specific responses to Dex versus Beta were observed. At >+/-2-fold change 126 genes were significantly different in the Dex versus Beta female transcriptome, 146 in the male transcriptome with 18 genes unique to both male and female transcriptome. Ingenuity Pathway Analysis revealed that the most significantly altered pathway altered (Z score >2) with both sGCs is Inositol Phosphate metabolism. Cardiac hypertrophy, Tec kinase, and Th1 pathways were unique to Beta stimulation, whereas Melatonin, Neuropathic Pain and IL6 signaling pathways were specific to Dex stimulation. Both Dex and Beta significantly alter genes implicated in proliferation and differentiation as also described in other studies, therefore the biological response of NSC to sGCs stimulation was compared. Only Dex significantly decreased the rate of proliferation over a 72 hour. In-vitro differentiation studies reveal that both Dex and Beta reduced oligodendrocyte differentiation without altering neuronal differentiation when cells were exposed to sGCs as progenitors. However, when cells were exposed to sGCs during differentiation, Dex increased oligodendrocyte and neuronal maturation while Beta only increased oligodendrocyte differentiation. These results reveal gene targets, cellular pathways and processes that are differentially altered by prenatal Dex versus Beta exposure. Prenatal sGCs administration provides clear benefits for neonatal outcome, however, a detailed understanding of their targets in the brain is required to identify alternative sGCs drug regimens to reduce adverse neurological effects. Our finds may provide insights into the sex specific neurological outcomes observed in children exposed to sGCs in-utero.