Behavioral Responses to Novelty or to a Predator Stimulus Are Not Altered in Adult Zebrafish by Early Embryonic Alcohol Exposure.

Abstract

Fetal alcohol spectrum disorders (FASD) may vary in symptoms and severity. In the milder and more prevalent forms of the disease, behavioral abnormalities may include impaired social behavior, for example, difficulty interpreting social cues. Patients with FASD remain often undiagnosed due to lack of biomarkers, and treatment is unavailable because the mechanisms of the disease are not yet understood. Animal models have been proposed to facilitate addressing these problems. More recently, short exposure of the zebrafish embryo to low concentrations of alcohol was shown to lead to significant and lasting impairment of behavior in response to social stimuli. The impairment may be the result of abnormal social behavior or altered fear/anxiety. The goal of the current study was to investigate the latter. Here, we employed the alcohol exposure regimen used previously (exposure of 24th hour postfertilization embryos to 0.00, 0.25, 0.50, 0.75, or 1.00% vol/vol alcohol for 2hours), allowed the fish to reach adulthood, and measured the behavioral responses of these adults to a novel tank (anxiety-related behaviors) as well as to an animated image of a sympatric predator of zebrafish (fear-related behaviors). We found behavioral responses of embryonic alcohol-exposed adult fish to remain statistically indistinguishable from those of controls, suggesting unaltered anxiety and fear in the embryonic alcohol-treated fish. Given that motor and perceptual function was previously shown to be also unaltered in the adults after embryonic alcohol exposure, our current results suggest that the impaired response of these fish to social stimuli may be the result of abnormal social behavior.