Psychopharmacology (2012) 220:771–785 779 Fig. 3 Effect of altering reward size, α-flupenthixol, and reward omission on responding for sucrose under an ST(RI-120) schedule in rats. a Seeking response rates for different amounts of sucrose pellets (n=10). b Number of taking responses for different amounts of sucrose pellets (n=10). c Effect of α-flupenthixol on sucrose seeking (n=10). d Effect of α-flupenthixol on sucrose taking (n=10). e Effects of reward omission and reac- quisition on sucrose seeking: baseline response (session 0; closed symbol) followed by 10 reward omission sessions (ses- sions 1–10; open symbols), after which reacquisition took place (sessions 11–14; closed sym- bols) (n=9). f Effects of reward omission and reacquisition on sucrose taking: baseline response (session 0; closed symbol) followed by 10 reward omission sessions (sessions 1–10; open symbols), after which reacquisition took place (sessions 11–14; closed symbols) (n=9). Data are presented as mean presses/min ± SEM (seeking) or mean ± SEM taking responses. *p<0.05 for differ- ence between groups (a–d) or sessions (e, f) (paired t test) significantly differed from pretreatment with 0.25 and 0.5 mg/kg α-flupenthixol (0 vs. 0.25 mg/kg, Z9 = −2.075, p < 0.05; 0 vs. 0.5 mg/kg, Z9 = −1.990, p < 0.05). There was no effect of α-flupenthixol on responding for sucrose during the consecutive, drug-free, self-administration session (χ(3)2 = 3.809, NS; Table 1). Furthermore, 0.5 mg/ kg α-flupenthixol suppressed seeking to a greater extent than that seeking was suppressed during the first reward omission session (Z19 = −2.670, p < 0.01). Figure 4c shows that the breakpoint did not change during the first reward omission session compared to the last baseline session (Z9 = −0.931, NS), but in the subsequent reward omission sessions, seeking gradually declined (χ(19)2 = 116.890, p < 0.001). When sucrose was reintroduced, the breakpoint increased (Z9 = −2.091, p < 0.05), but only from the second reacquisition session onwards, seeking levels were com- parable to pre-reward omission sessions (baseline vs. first reacquisition session, Z9 = −2.091, p < 0.05; baseline vs. second reacquisition session, Z9 = −1.244, NS; baseline vs. third reacquisition session, Z9 = −0.923, NS; baseline vs. fourth reacquisition session, Z9 = −1.540, NS; baseline vs. fifth reacquisition session, Z9 = −1.887, NS). FR-1 schedule with cocaine or sucrose reinforcement Figure 5a shows that α-flupenthixol altered cocaine self- administration in animals responding under an FR-1 schedule of reinforcement (F4, 24 = 6.282, p = 0.01). Doses of 0.05 and 0.25 mg/kg α-flupenthixol increased cocaine self-administration compared to vehicle treatment (0 vs. 0.05 mg/kg, t6 = −3.094, p < 0.05; 0 vs. 0.25 mg/kg, t6 = −2.647, p < 0.05), while 0.5 mg/kg α-flupenthixol decreased responding for cocaine compared to vehicle treatment (0 vs. 0.5 mg/kg, t6 = 2.601, p < 0.05). α- Flupenthixol did not affect inactive lever presses (F4, 24 = 1.541, NS). Figure 5b shows that α-flupenthixol also affected sucrose self-administration in animals responding under an FR-1 schedule of reinforcement (F4, 28 = 3.463, p < 0.05). The dose of 0.5 mg/kg α-flupenthixol decreased responding for sucrose compared to vehicle treatment (0 vs.