Teratogenic effects of ethanol exposure on zebrafish visual system development

Area of Science:

• Developmental Biology
• Neuroscience
• Toxicology

Background:

• Ethanol consumption during pregnancy is a leading cause of preventable birth defects, collectively known as fetal alcohol spectrum disorders (FASDs).
• Cyclopia, a severe congenital malformation characterized by a single eye, is a hallmark of the most extreme form, fetal alcohol syndrome (FAS).
• Understanding the mechanisms underlying ethanol's teratogenic effects on vertebrate development is crucial for prevention and intervention strategies.

Purpose of the Study:

• To investigate the teratogenic effects of ethanol on visual system development in zebrafish embryos.
• To determine strain-specific susceptibility to ethanol-induced cyclopia and survival rates.
• To analyze ethanol's impact on the cytoarchitecture of the retina and optic tectum.

Main Methods:

• Zebrafish embryos from four strains (AB, EK, GL, TL) were exposed to varying ethanol concentrations (1.0%, 1.5%, 2.4%) during eye morphogenesis.
• Survival rates of cyclopic larvae were monitored throughout development.
• Histological analysis was performed to examine cytoarchitectural alterations in the retina and optic tectum.

Main Results:

• Zebrafish strains GL and AB showed higher percentages of cyclopia at 2.4% ethanol, while EK exhibited higher cyclopia rates at 1.0% and 1.5% ethanol.
• The EK strain demonstrated the highest survival rates across all tested ethanol concentrations.
• Ethanol exposure caused delayed retinal lamination, reduced pigmented epithelium thickness, and disrupted optic tectum lamination.

Conclusions:

• Zebrafish embryos exhibit strain-dependent sensitivity to ethanol-induced cyclopia.
• The EK zebrafish strain is a valuable model for studying ethanol's teratogenic effects on visual system development.
• Ethanol significantly disrupts the morphogenesis of the retina and optic tectum, contributing to visual pathway abnormalities in FAS.