Transient catabolic state with reduced IGF-I after antenatal glucocorticoids

Area of Science:

• Neonatal Medicine
• Endocrinology
• Biochemistry

Background:

• Antenatal glucocorticoid (GC) administration is crucial for reducing neonatal morbidity in preterm births.
• However, concerns exist regarding potential growth restriction associated with GC exposure.
• The impact of antenatal GCs on key metabolic substrates and growth factors remains incompletely understood.

Purpose of the Study:

• To investigate the effects of antenatal glucocorticoid (GC) exposure on nutrient substrates (glucose, free fatty acids, amino acids) and insulin-like growth factor-I (IGF-I) and IGF-binding protein-1 (IGFBP-1) in preterm newborns.
• To explore the relationship between GC exposure timing, nutrient substrate levels, and growth parameters.

Main Methods:

• Analysis of umbilical vein plasma from 91 preterm newborns exposed to one course of antenatal GC and 49 unexposed controls.
• Measurement of glucose, free fatty acids (FFA), amino acids (AA), IGF-I, and IGFBP-1 concentrations.
• Calculation of the homeostasis model assessment of insulin resistance (HOMA-IR) index.

Main Results:

• Recent GC exposure (within 48 hours of birth) was associated with increased glucose, FFA, and AA concentrations, and a higher HOMA-IR index.
• IGF-I concentrations were significantly lower in newborns recently exposed to GCs.
• The increase in amino acids, particularly glutamine and alanine, was more pronounced in newborns with lower birth weight z-scores, and was inversely correlated with IGF-I levels.

Conclusions:

• Antenatal GC administration induces a transient catabolic state in preterm newborns, affecting all major nutrient substrates.
• A temporary decrease in IGF-I concentrations is observed following antenatal GC exposure.
• These metabolic and hormonal changes may contribute to the growth-inhibitory effects observed with repeated antenatal GC administration, highlighting the need for further research into the role of IGF-I.