Behavioral impact of condensed repeated ethanol dosing on withdrawal in adult zebrafish (Danio rerio)

Zebrafish ( Danio rerio ) are a widely used animal model to study a variety of neuropsychiatric disorders, including drug addiction. Existing paradigms to examine alcohol addiction use repeated daily or continuous ethanol exposures over multiple days. The present study evaluated a condensed repeated dosing paradigm, involving three 1-h ethanol doses (0.8%) per day over 5 days. To examine ethanol withdrawal, locomotor and anxiety-like behavior was assessed at 2, 4, and 8 days following the dosing schedule, using the open field test. There was a significant increase in immobility and angular velocity with ethanol regardless of withdrawal duration. At 8 days of withdrawal, ethanol-treated fish spent significantly less time highly mobile compared to controls. Likewise, there was a change in zone preference at 8 days of withdrawal, with ethanol-treated fish spending significantly more time in the transition zone and less time in the thigmotaxis zone compared to controls. No other significant zone preferences or sex differences were found. These findings suggest that the condensed repeated dosing paradigm produces a measurable behavioral withdrawal phenotype. This dosing schedule is an effective and efficient approach for high-throughput drug addiction research in adult zebrafish and may be useful for evaluating many pharmacological treatments.