Molecular and morphological changes in zebrafish following transient ethanol exposure during defined developmental stages

Abstract

Alcohol is a teratogen that has diverse effects on brain and craniofacial development, leading to a constellation of developmental disorders referred to as fetal alcohol spectrum disorder (FASD). The molecular basis of ethanol insult remains poorly understood, as does the relationship between molecular and behavioral changes as a consequence of prenatal ethanol exposure. Zebrafish embryos were exposed to a range of ethanol concentrations (0.5–5.0%) during defined developmental stages, and examined for morphological phenotypes characteristic of FASD. Embryos were also analyzed by in situ hybridization for changes in expression of defined cell markers for neural cell types that are sonic hedgehog-dependent. We show that transient binge-like ethanol exposures during defined developmental stages, such as early gastrulation and early neurulation, result in a range of phenotypes and changes in expression of Shh-dependent genes. The severity of fetal alcohol syndrome (FAS) morphological phenotypes, such as microphthalmia, depends on the embryonic stage and concentration of alcohol exposure, as does diminution of retinal Pax6a or forebrain and hindbrain GAD1 gene expression. We also show that changes in eye and brain morphology correlate with changes in Pax6a and GAD1 gene expression. Our results therefore show that transient binge-like ethanol exposures in zebrafish embryos produce the stereotypical morphological phenotypes of FAS, with the severity of phenotypes depending on the developmental stage and alcohol concentration of exposure.

Transient Exposure to Ethanol during Zebrafish Embryogenesis Results in Defects in Neuronal Differentiation: An Alternative Model System to Study FASD

“…Although pax2a expression is not affected in the MHB, we observed a decrease in the expression of this gene in the region of the optic stalk after the exposure of ethanol, as previously reported using other tools [38]. These results and other studies that have used different gene expression analyses and experimental design [14], [26], [48], [57] support the idea that eye development is a major target in the development of the disease.…”

A Comparison of the Different Animal Models of Fetal Alcohol Spectrum Disorders and Their Use in Studying Complex Behaviors

“…These deficits were also accompanied by changes in gene expression (151, 153, 154). These effects were dependent on the dose of ethanol used and the developmental timing and length (chronic vs. acute) of exposure, with the blastula, gastrulation, and somitogenesis periods being particularly sensitive to the effects of ethanol (48, 150).…”

Influences of acute ethanol exposure on locomotor activities of zebrafish larvae under different illumination

“…Behaviorally, the adult zebrafish with 1% ethanol treatment for 60 min demonstrated significantly reduced swimming distance than the non-treated control group. Zebrafish embryos receiving acute ethanol treatment at concentrations of 1%e5% from 8 to 10 hours post-fertilization (hpf) or 24e27 hpf demonstrated tissue ethanol contents ranging from 50 mM to 300 mM (Zhang et al, 2014). Acute ethanol treatments of AB and TU strain zebrafish embryos at concentrations up to 1% (v/v %) for 2 h at 24 hpf resulted in tissue ethanol contents that were approximately 8% of the environmental ethanol concentrations (Mahabir, Chatterjee, & Gerlai, 2014).…”