Induction of conditioned taste aversion with a self-administered substance in rats

Drugs of abuse such as cocaine induce a paradoxical aversive effect when paired with a novel taste. When a novel gustatory cue is paired with drugs of abuse the resulting conditioned effect is the avoidance of the novel taste. A conditioning paradigm was developed in order to pair saccharin with self-administered cocaine. Rats were trained to lever-press for sweetened milk in an operant chamber and then implanted with an intrajugular catheter for cocaine self-administration. (SA). After recovery from surgery, food and water access were restricted and the operant behavior was reestablished using contingent milk. Pairings of 10-min saccharin access followed by 1-h cocaine (0.125 mg/kg per injection) SA sessions were alternated daily with pairings of 10-min water access followed by 30-min SA sessions of oral milk and i.v. saline, delivered simultaneously. Pairings were conducted once a day for 10 days. After four sessions of cocaine self-administration there was no significant decrease in saccharin intake. However, rats that avoided saccharin also self-administered more cocaine than non-avoiding rats. These results suggest that the development of taste aversion is accompanied by an acceptance of the drug rather than an aversion to it. (C) 2001 Elsevier Science B.V. All rights reserved.