Strain dependent neurochemical changes induced by embryonic alcohol exposure in zebrafish

Abstract

Fetal Alcohol Spectrum Disorder (FASD) is a preventable disease of the child resulting from alcohol (ethanol) consumption by pregnant women. Despite being preventable, FASD represents a prevalent problem throughout the world. Embryonic alcohol induced abnormalities in behavioral responses to social stimuli have been shown in humans and zebrafish. The neurobiological mechanisms underlying the abnormalities remain obscured. Here we start a mechanistic analysis by investigating the effect of embryonic alcohol exposure on the neurochemistry of zebrafish. The differing severity of symptoms seen in FASD may be partially due to genetic factors. To explore such genetic effects, here we analyzed two distinct zebrafish strains: AB and TU. Zebrafish were exposed to one of the following concentrations of alcohol, 0.00%, 0.25%, 0.50%, 0.75%, or 1.00% (vol/vol %) at 24hours post-fertilization (hpf) for 2h. From whole brain extracts we analyzed the amount of neurotransmitters dopamine and serotonin and their metabolites across 4 different developmental time points: 15, 40, 70 and 102days post-fertilization (dpf) using high performance liquid chromatography (HPLC). AB zebrafish exhibited a significant dose dependent embryonic alcohol exposure effect which increased in robustness with age. However, TU showed no such concentration effect: the levels of neurochemicals remained mainly unaltered by embryonic alcohol exposure in all age groups. We also analyzed the amount of alcohol reaching the embryo in the two strains and ruled out the possibility that TU has a more protective chorion. We conclude that the uncovered strain differences are due to genetic differences that protect TU from the deleterious effects of embryonic alcohol exposure.