Glucocorticoid Receptor Expression Pattern in Very Low Birth Weight Infants Changes Drastically within the First Week of Life.

Introduction: We herein examined changes in expression levels of the glucocorticoid receptor subtypes GRα and GRβ in very low birth weight (VLBW) and term infants to clarify time-dependent changes in glucocorticoid sensitivity after birth. Methods: Whole blood samples were collected at birth and on postnatal days 4–7, and the mRNA expression levels of GRα and GRβ were measured using RT-qPCR. The relative gene expression levels of GRα and GRβ as the target genes normalized to actin beta as the endogenous control were calculated by the comparative cycle threshold method. Results: The GRα/GRβ expression ratio at birth was significantly lower in 32 VLBW cesarean section (CS) infants than in term planned CS infants (median [IQR], 1.5 [1.1–1.8]- and 1.1 [0.7–1.6]-fold change, p < 0.05). Furthermore, the GRα/GRβ expression ratio increased from day 0 to days 4–7 (1.0 [0.6–1.4]- and 1.7 [0.6–1.4]-fold change, p < 0.01) in 43 VLBW infants. Discussion/Conclusion: The present results suggest that glucocorticoid sensitivity in VLBW infants increases after birth and this rapid change may play a role in surviving critical postnatal events. [ABSTRACT FROM AUTHOR]