Fig. 1.
Omission cue-induced suppression (OCIS) procedure for cocaine seeking. A total of 63 rats were initially used and randomly assigned to four experimental groups: Compulsivity test, Cocaine (1.0 or 2.0 mg/kg), and Stress priming groups (n = 14,16,16,17). Of which, 45 rats were retained for statistical analyses (see Methods). Final Ns for each group are described below. All data are mean and SEM. Gray open circles on bar charts depict individual data-points. a Timeline and schedule. b Responses during the first 14 days of Self-administration (SA) training. c Responses during the first and last 10 days of Discrimination training. d Compulsivity tests for animals’ resistance to cocaine-paired punishment after cocaine access through the SA training phase vs. both SA and Discrimination training phases. Each cocaine infusion was paired with an electric foot-shock (0.8 mA, 1-s). n = 6,6. Student’s t-test: t(10) = 3.20, *P < 0.05. e Responses during the first 2-h block of Discrimination test to determine cocaine S-‘s action against cocaine availability cues (active lever and light-cue). n = 33. Paired t-test: t(32) = 11.50, *P < 0.001. Duplicate data-points from multiple subjects are not overlaid on this Figure for clarity because n = 33. Thus, these dot plots represent the data range. f, g Responses during the second and third 2 h-blocks of Discrimination test (within-session reinstatement) to determine cocaine S-‘s action against cocaine priming (10 and 20 mg/kg, IP). Two-way repeated measures ANOVA for the 10 mg/kg group (n = 12): Priming (F(1,11) = 19.20, P < 0.001) main effects and Cue-Test x Priming interaction (F(1,11) = 10.34, P < 0.01). Two-way repeated measures ANOVA for the 20 mg/kg group (n = 10): Cue-Test (F(1,9) = 42.02, P < 0.001) and Priming (F(1,9) = 47.19, P < 0.001) main effects, and Cue-Test x Priming interaction (F(1,9) = 94.49, P < 0.001). †P < 0.001 vs. IP saline. *P < 0.01–0.05 vs. No S-. Tukey HSD test. h Responses during the second and third 2 h-blocks of Discrimination test to determine cocaine S-‘s action against stress priming (mild electric foot-shock, intermittent, 10 min, 0.8 mA). n = 11. Two-way repeated measures ANOVA: Cue-Test (F(1,10) = 17.41, P < 0.01) and Priming (F(1,10) = 121.79, P < 0.001) main effects, and Cue-Test x Priming interaction (F(1,10) = 15.36, P < 0.01). †P < 0.01 vs. sham foot-shock. *P < 0.05 vs. No S-. Tukey HSD test