Failure to Find Postshock Increases in Ethanol Preference

Volpicelli at al. (Alcohol Clin Exp Res 14:913-916, 1990) found that rats given a choice between drinking 5% ethanol and water showed enhanced ethanol preference after daily sessions of shock, relative to No-Treatment controls. In our first experiment, rats were given a choice between 5% ethanol and isocaloric sucrose after daily sessions of shock. On shock days, rats received either 2 or 60 shocks over 1 hr. The 60-Shock group increased its ethanol preference from the baseline phase to the postshock phase, whereas the 2-Shock group decreased its ethanol preference from the baseline phase to the shock phase. However, the ethanol preferences of the two groups were not significantly different from each other during any phase. In four subsequent experiments, Shock, No-Shock, and No-Treatment groups were given a choice between 5% ethanol and water. The experiments varied on: whether the treatments and measurements of consumption occurred in the light versus dark phase of the cycle, and whether there was one measurement per day or four. Baseline ethanol preference varied widely between experiments. In none of the experiments did shock differentially enhance ethanol preference. The findings of Volpiceli et al. were not replicated.