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. 2022 Nov 24;16:1035350. doi: 10.3389/fnbeh.2022.1035350

FIGURE 4.

FIGURE 4

Female and male rats front-load oxycodone intake. Data are shown as the average number (±SEM) of infusions (A–C) and active lever presses (D–F) in 15-min bins from the first hour of escalation day 9 (ESC d9) and day 22 (ESC d22) in male and female rats. For each treatment condition: LgA (A,D), ShA (B,E), and Sal (C,F), 3-way ANOVAs (Sex × ESC day × Time) were calculated. For oxycodone self-administration under LgA and ShA conditions, rats self-administered more oxycodone in the first 15-min bin compared to the last 15-min bin (i.e., front-loading), and overall oxycodone intake was greater on ESC d22 compared to ESC d9. This was determined through main effects or interactions of ESC day and Time. #p < 0.05, ##p < 0.01, main effect of Time; **p < 0.01, Dunnett’s multiple comparisons to the 0–15 min bin; δp < 0.05, δδp < 0.01 Bonferroni’s multiple comparisons of ESC d9 to ESC d22 per time bin. N: LgA (19 females, 20 males); ShA (15 females, 13 males); Sal (8 females, 6 males).