Table 1.
Separate analyses of high vs. low performers for experiments 1–4.
Table 2.
Separate analyses of high vs. low performers for experiments 5–8.
Figure 1.
Effects of the VMAT-2 inhibitor and DA depleting agent TBZ on PROG/chow performance.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), TBZ produced significant decreases at 0.5, 0.75 and 1.0 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by any dose tested (D). (* p<0.05, different from vehicle).
Figure 2.
Effects of the DA D1 antagonist ecopipam on PROG/chow performance.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), ecopipam produced significant decreases at 0.1 and 0.2 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by any dose tested (D). (* p<0.05, different from vehicle).
Figure 3.
Effects of the DA D2 antagonist eticlopride on PROG/chow performance.
Mean (+SEM) total lever presses (A) and highest ratio achieved (B) were significantly decreased by 0.04 and 0.08 mg/kg of eticlopride. Additionally, active lever time (measured in seconds, C) was significantly reduced at 0.08 mg/kg eticlopride. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by any dose tested (D). (* p<0.05, different from vehicle).
Figure 4.
Effects of the cannabinoid CB1 antagonist and putative appetite suppressant AM4113 on PROG/chow performance.
Mean (+SEM) total lever presses (A) and highest ratio achieved (B) were significantly decreased by 16.0 mg/kg of AM4113. Active lever time (measured in seconds, C) was not affected by AM4113 at any dose tested. Chow consumption (mean +SEM, in grams) was significantly reduced at 4.0, 8.0 and 16.0 mg/kg of AM4113 (D). (* p<0.05, different from vehicle).
Figure 5.
The adenosine A2A antagonist MSX-3 reverses the effects of TBZ on the PROG/Chow procedure.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), TBZ produced significant decreases at 0.75 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by TBZ (D). MSX-3 reversed the effects on total lever presses, highest ratio achieved and active lever time at both 1.0 and 2.0 mg/kg. (# p<0.05, different from vehicle; * p<0.05, different from TBZ alone).
Figure 6.
The DA uptake inhibitor and common antidepressant bupropion reverses the effects of TBZ on the PROG/Chow procedure.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), TBZ produced significant decreases at 0.75 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by TBZ (D). Bupropion reversed the effects on total lever presses, highest ratio achieved and active lever time at 15.0 mg/kg. (# p<0.05, different from vehicle; * p<0.05, different from TBZ alone).
Figure 7.
The MAO-B inhibitor and putative antidepressant deprenyl reverses the effects of TBZ on the PROG/Chow procedure.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), TBZ produced significant decreases at 0.75 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by TBZ (D). Deprenyl reversed the effects on total lever presses, highest ratio achieved at 5.0 mg/kg. In addition, active lever time was increased at 2.5, 5.0 and 10.0 mg/kg. Chow consumption was significantly decreased at 10 mg/kg. (# p<0.05, different from vehicle; * p<0.05, different from TBZ alone).
Figure 8.
The COMT inhibitor Tolcapone fails to reverse the effects of TBZ on the PROG/Chow procedure.
On measures of lever pressing, mean (+SEM) total lever presses (A), highest ratio achieved (B), and active lever time (measured in seconds, C), TBZ produced significant decreases at 0.75 mg/kg. Chow consumption (mean +SEM, in grams) during test sessions was unaffected by TBZ (D). Tolcapone did not reverse the effects on total lever presses, highest ratio achieved or active lever time at any dose tested (# p<0.05, different from vehicle).