Initiation of ethanol-maintained responding using a schedule-induction procedure in free feeding rats

A schedule-induced adjunctive drinking procedure was used to initiate ethanol self-administration in free feeding rats. The rats were first trained on a FI 90-sec schedule with 20% sucrose reinforcement, and then ethanol was made concurrently available on a CRF schedule on a second lever. After 25 concurrent sessions, the sucrose was removed and the ethanol response requirement was brought to FR8. Finally, ethanol concentrations were varied up to 40%. Of 11 rats, 8 responded for sucrose on the FI 90 sec schedule, and 5 of those responded for 40% ethanol at FR8. These results were compared to previous studies using the same procedure in food-restricted rats and other procedures in free feeding rats. Possible explanations for the lower success using schedule induction in nondeprived rats were discussed.