Number of active lever presses for rats responding for either food or cocaine under an FR5TO1-min schedule of reinforcement
| Vehicle | Ro 60-0175 | |||||||
|---|---|---|---|---|---|---|---|---|
| 0.3 mg/kg | 1 mg/kg | 3 mg/kg | ||||||
| F | Coc | F | Coc | F | Coc | F | Coc | |
| Total lever presses | 822 ± 149 | 95 ± 12 | 698 ± 114 | 94 ± 8 | 432 ± 137 | 66 ± 11 | 32 ± 23 | 26 ± 121-160 |
| Time-out responses | 562 ± 144 | 18 ± 8 | 454 ± 101 | 20 ± 5 | 250 ± 1071-150 | 20 ± 7 | 9 ± 61-150 | 6 ± 3 |
| Active responses | 260 ± 8 | 78 ± 5 | 244 ± 15 | 74 ± 5 | 181 ± 37 | 46 ± 81-160 | 24 ± 17 | 20 ± 91-160 |
The data shown are the total number of lever presses recorded over the entire 60-min test session and the number of presses made under the active and time out phase of the session. Note that at the 0.3 to 1 mg/kg dose of Ro 60-0175, the animals were emitting a much higher number of lever presses under the food-maintained than in the cocaine-maintained schedule. This suggests that, at these doses of Ro 60-0175, reductions in cocaine self-administration were not simply due to motor disruption.