Autoshaping i.v. cocaine self-administration in rats: effects of nondrug alternative reinforcers on acquisition.
The purpose of this experiment was to examine the effects of a nondrug alternative reinforcer and feeding conditions on the acquisition of cocaine self-administration. Rats were autoshaped to press a lever that resulted in a 0.2 mg/kg i.v. cocaine infusion. Responses on the lever were monitored during six consecutive autoshaping sessions that occurred each day. A retractable lever was inserted into the operant chamber on a random time 60 s schedule 10 times per session for six sessions that began each hour. Each day the six autoshaping sessions were followed by a 6-h cocaine self-administration session. During self-administration the lever remained extended, and each response on the lever resulted in a cocaine infusion (0.2 mg/kg). The criterion for acquisition of cocaine-reinforced behavior was met when there were 5 consecutive days during which the mean number of infusions during the 6-h self-administration session was at least 100. This procedure was repeated daily until the criterion was met or 30 days elapsed. The rats were also trained to respond on lick-operated automatic drinking devices that delivered 0.05 ml water or a glucose and saccharin solution (G + S) contingent upon each lick response. Five groups of 12-14 rats were compared. The first four groups constituted a 2 x 2 factorial design whereby either G + S or water was available in the home cage for 3 weeks before autoshaping began and G + S or water was available in the operant chamber during autoshaping. These groups were limited to 20 g food per day and all had free access to water.(ABSTRACT TRUNCATED AT 250 WORDS)
Carroll
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Department of Psychiatry, University of Minnesota Medical School, Minneapolis 55455.
Lac
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D000818:Animals; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D004435:Eating / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012055:Reinforcement Schedule; D012054:Reinforcement, Psychology; D012439:Saccharin / Q000494:pharmacology; D012646:Self Administration
D012439:Saccharin; D003042:Cocaine; D005947:Glucose