Prenatal
ethanol exposure is known to cause
neurodevelopmental disorders. While high prevalence of
epilepsy is observed among the children whose mothers abused alcohol during pregnancy, the results from animal studies are conflicting. Here, we investigated whether embryonic exposure to
ethanol can increase the susceptibility to
pentylenetetrazole (PTZ)-induced
seizures in larval zebrafish. Embryos at 3 hours post-fertilization (hpf) were exposed to
ethanol at the concentrations ranging from 0.25% to 1% for 21 hours. Control and
ethanol-exposed larvae were challenged with PTZ at 7 days post-fertilization (dpf) at the concentrations of 2.5, 5 or 15 mM. The seizure behavior of larvae was recorded and analyzed using EthoVision XT 11. We found that embryonic
ethanol exposure increased the percentage of larvae exhibiting typical stage II and III seizure and resulted in a significant reduction in stage I, II and III seizure latency in an
ethanol concentration-dependent manner. Embryonic exposure to
ethanol also significantly increased the severity of PTZ-induced
seizures in larvae, as demonstrated by increased total distance traveled and the duration of mobility. This is the first demonstration that
ethanol exposure during early embryonic stage can reduce the threshold for chemically induced
seizures and increase the severity of seizure behavior in larval fish.