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.
Gomez
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Department of Pharmacology, University of Michigan, 1301 MSRB-III, West Medical Center Drive, Ann Arbor, MI 48109-0632, USA. felipeg@umich.edu
D000818:Animals; D001362:Avoidance Learning; D003042:Cocaine / Q000008:administration & dosage; D003216:Conditioning, Operant; D008297:Male; D008892:Milk; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin / Q000008:administration & dosage; D012646:Self Administration; D013649:Taste / Q000502:physiology*
D012439:Saccharin; D003042:Cocaine