Supplementary Material for: 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 to 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 to 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 suggests that glucocorticoid sensitivity in VLBW infants increases after birth and this rapid change may play a role in surviving critical postnatal events.

引言 本研究旨在探究极低出生体重（very low-birth weight, VLBW）儿与足月新生儿体内糖皮质激素受体亚型GRα和GRβ的表达水平变化，以明确出生后糖皮质激素敏感性的时序性改变。
方法 于新生儿出生时及出生后第4~7天采集全血样本，采用逆转录实时荧光定量聚合酶链反应（RT-qPCR）检测GRα与GRβ的mRNA表达水平。以β-肌动蛋白（actin beta）作为内参基因，采用比较循环阈值法计算靶基因GRα与GRβ的相对基因表达量。
结果 32例行剖宫产（cesarean section, CS）的极低出生体重儿出生时的GRα/GRβ表达比值，显著低于足月择期剖宫产新生儿（中位数（四分位间距）分别为1.5（1.1~1.8）倍变化与1.1（0.7~1.6）倍变化，p<0.05）。此外，43例极低出生体重儿的GRα/GRβ表达比值自出生第0天至第4~7天呈升高趋势（分别为1.0（0.6~1.4）倍变化与1.7（0.6~1.4）倍变化，p<0.01）。
讨论与结论 本研究结果显示，极低出生体重儿体内的糖皮质激素敏感性在出生后有所升高，这种快速变化或许在新生儿出生后关键事件的存活过程中发挥重要作用。