The effects of cocaine in a gustatory avoidance paradigm: a procedural analysis.

When the presentation of a novel food to a rat is followed by the injection of certain compounds, the animal consumes less of that food on subsequent presentations. Conflicting results have been obtained when cocaine is used in this gustatory avoidance paradigm. In the present study, fluid intake of rats was limited to a single presentation, seven days a week. Following the determination of baseline water intake, sweetened fluid was given during the session following the determination of baseline water intake, sweetened fluid was given during the session followed by an injection of cocaine. In Experiment 1, 24.0 mg/kg cocaine-fluid pairings occurred on alternate days with two-bottle preference tests occurring between pairings. Animals treated with cocaine had lower preference ratios than saline controls although both groups consumed more novel fluid than tap water. In Experiment 2, preexposure to the fluid prior to pairing it with cocaine eliminated differences between cocaine and saline treated rats. In Experiment 3 no effect of cocaine on novel fluid consumption was seen in male or female rats when 24.0 mg/kg cocaine-fluid pairings were given for five consecutive days. In addition, 36 mg/kg cocaine when paired with novel fluid every other day failed to induce an avoidance response in Experiment 4. These results indicate that cocaine is a weak avoidance-producing agent in the gustatory avoidance paradigm, and suggests the need for a standardized procedure for studying drugs in this paradigm.