High Corticosterone Affects Somite Development During Early Avian Embryogenesis

Area of Science:

• Developmental biology
• Endocrinology
• Molecular biology

Background:

• Maternal stress is linked to adverse embryonic and fetal development.
• Mechanisms of stress hormone influence on early development, particularly during somitogenesis, are not well understood.
• Disruptions in early embryogenesis can affect body plan formation and tissue organization.

Purpose of the Study:

• To investigate the effects of acute corticosterone exposure on somite phenotype and Sonic hedgehog (SHH) signaling in early avian embryogenesis.
• To explore potential molecular mechanisms underlying stress-induced developmental alterations.

Main Methods:

• Utilized the avian chick embryo model (Hamburger-Hamilton stage 12).
• Administered acute corticosterone (15 µg) via yolk sac injection to mimic high-stress conditions.
• Performed macroscopic examination, histological assessment, and molecular analyses (gene expression profiling).

Main Results:

• Corticosterone-treated embryos showed increased inter-somitic distances, indicating altered somite organization.
• Histological analysis revealed cellular degeneration or cell death in treated embryos.
• Significant downregulation of SHH and GLI1 expression was observed, suggesting impaired SHH signaling.
• Reduced TGFβ4 and elevated HIF2α expression were noted, hinting at stress-induced hypoxic responses.

Conclusions:

• Elevated corticosterone exposure negatively impacts somite development and SHH signaling during early embryogenesis in chick embryos.
• Findings suggest a potential link between maternal stress, hypoxic responses, and altered developmental signaling pathways.
• This study provides novel in vivo evidence on the effects of corticosterone on SHH-associated somite development.