Alcohol consumption is preferred to water in rats pretreated with intravenous cocaine

Clinical and anecdotal reports suggest a high incidence of alcohol administration during cocaine use, potentially as a means to diminish the aversive effects of cocaine that follow the initial positive drug effects. We have previously shown that in the operant runway, oral ethanol significantly reduces the approach–avoidance retreats that develop in response to IV cocaine. The current study was intended to test whether rats given the same dose of IV cocaine administered in our previous study would choose to consume ethanol rather than water in a two bottle choice paradigm. We also examined whether significant serum levels of the psychoactive cocaine metabolite, cocaethylene, were found in our animals that may account for the preference for ethanol. Animals pretreated with cocaine drank significantly more ethanol than did animals pretreated with saline. There were no measurable levels of cocaethylene at 10 or 40 min post-cocaine and extremely low values at the 20-min time point, indicating that cocaethylene formation does not reinforce the co-administration of cocaine and alcohol in rats. These data demonstrate that the presence of cocaine serves as a primary factor in the preference for alcohol in thirsty rats, potentially to reduce the well-documented negative/anxiogenic properties of cocaine.