Social deficits following embryonic ethanol exposure arise in post‐larval zebrafish

Abstract

Prenatal alcohol exposure is the leading cause of birth defects, collectively termed fetal alcohol spectrum disorders (FASD). In the United States and Canada, 1 in 100 children will be born with FASD. Some of the most commonly debilitating defects of FASD are in social behavior. Zebrafish are highly social animals, and embryonic ethanol exposure from 24 to 26 hours post-fertilization disrupts this social (shoaling) response in adult zebrafish. Recent findings have suggested that social behaviors are present in zebrafish larvae as young as 3 weeks, but how they relate to adult shoaling is unclear. We tested the same ethanol-exposed zebrafish for social impairments at 3 weeks then again at 16 weeks. At both ages, live conspecifics were used to elicit a social response. We did not find alcohol-induced differences in behavior in 3-week-old fish when they were able to see conspecifics. We do find evidence that control zebrafish are able to use nonvisual stimuli to detect conspecifics, and this behavior is disrupted in the alcohol-exposed fish. As adults, these fish displayed a significant decrease in social behavior when conspecifics are visible. This surprising finding demonstrates that the adult and larval social behaviors are, at least partly, separable. Future work will investigate the nature of these nonvisual cues and how the neurocircuitry differs between the larval and adult social behaviors.

Does early ethanol exposure increase seeking‐like behavior in zebrafish?

“…Redesigning our protocol to test different cues instead of stripes and extending the alcohol association period (more than only one day) will be needed to clarify the specific reason for such a difference. Similar inconsistent results between various ages were observed in the study by Fernandes and colleagues (Fernandes et al., 2019), in which the authors observed embryonic alcohol exposure disruptive shoaling response in adults but not in larvae zebrafish. The authors refer to neurocircuitry differences between larval and adult social behaviors, which can also be a plausible explanation for the results obtained in our study on CPP.…”

Fetal alcohol spectrum disorder predisposes to metabolic abnormalities in adulthood

“…EAE had no detectable impact on food consumption in adult males, suggesting that it is an unlikely mechanism for increased adiposity ( Figure 4B). Multiple studies have demonstrated that EAE affects zebrafish swimming behaviors (35)(36)(37)(38). To determine whether reduced locomotion was present in adults after EAE, we assessed activity level (35,(39)(40)(41)(42)(43)(44).…”

Zebrafish Models of Craniofacial Malformations: Interactions of Environmental Factors

“…Importantly, the chorion, which surrounds the early zebrafish embryo, appears freely permeable for ethanol. Zebrafish embryonic ethanol levels reach approximately 25–35% of the embryo medium level ( Blader and Strahle, 1998 ; Ali et al, 2011 ; Fernandes et al, 2019 ). In zebrafish, both short-term and chronic ethanol exposure increase the incidence of craniofacial malformations.…”