Sequential developmental changes in holoprosencephalic mouse embryos exposed to ethanol during the gastrulation...

Area of Science:

• Developmental biology
• Teratology
• Neuroscience

Background:

• Prenatal ethanol exposure is a known cause of holoprosencephaly in humans and animals.
• The precise teratogenic window and mechanism of ethanol-induced holoprosencephaly remain unclear.
• This study investigates ethanol's effects on craniofacial development and gene expression in mouse embryos.

Purpose of the Study:

• To examine morphological changes in mouse craniofacial structures following prenatal ethanol exposure.
• To evaluate the impact of ethanol on key developmental gene expression patterns.
• To elucidate the teratogenic mechanism of ethanol-induced holoprosencephaly.

Main Methods:

• Pregnant C57BL/6J mice received ethanol (30 mg/kg) on day 7 of gestation.
• Embryos/fetuses were examined at embryonic day 10.5 (E10.5) and E15.5 for gross and histological abnormalities.
• In situ hybridization was used to analyze Shh and Nkx2.1 gene expression at E8.5.

Main Results:

• Ethanol-exposed fetuses exhibited gross and histological brain and facial abnormalities, particularly affecting midline structures.
• Absence of midline commissural fibers was observed in ethanol-exposed fetuses, even without external malformations.
• Down-regulation of Sonic hedgehog (Shh) and Nkx2.1 gene transcripts was detected in ethanol-exposed embryos.

Conclusions:

• Ethanol exposure during critical embryonic development perturbs developmental gene expression.
• This perturbation leads to holoprosencephaly and other midline craniofacial malformations.
• Histological brain abnormalities are a consequence of ethanol's teratogenic effects on gene expression.