Cocaine-induced Conditioned Taste Aversions in Male and Female Wistar Rats

After an initial period of adaptation to 20 min per day of limited water availability, male and female Wistar rats were allowed access to water or a 0.1% sodium-saccharin solution. Saccharin exposures were followed by the subcutaneous administration of 0, 5, 10 or 20 mg/kg cocaine for different groups of rats. Four pairings of the saccharin solution with cocaine administration resulted in a consistent decrease in saccharin consumption only in female subjects injected with the largest dose of cocaine (20 mg/kg). Choice testing in which subjects could choose between two drinking tubes, one containing water, the other one containing the saccharin solution, was then conducted during extinction. During four of such experimental sessions, subjects which had previously been injected with vehicle mostly consumed the saccharin solution or showed a position bias. Conditioned taste aversions were not only observed in the group of female subjects injected with 20 mg/kg cocaine, but also in males previously treated with 20 mg/kg cocaine. In addition, compared to vehicle control groups, males and females injected with 5 and 10 mg/kg cocaine tended to avoid the saccharin solution in favor of regular water. It is suggested that previous failures to obtain consistent cocaine-mediated taste aversions may have been a function of the experimental procedures used to assess cocaine's efficacy in inducing conditioned taste aversions.