Fig. 3.

a Left discrimination between active and inactive nosepokes throughout the self-administration paradigm in non-escalated rats. Right mean ± SEM minutes of vapor during the self-administration paradigm in non-escalated rats. b Left discrimination between active and inactive nosepokes throughout the self-administration paradigm in escalated rats. Right mean ± SEM minutes of vapor during the self-administration paradigm in escalated rats. The animals presented escalation of intake starting from session 13 (*p < 0.05, vs. last day of 2 min) and continued increasing their intake (***p < 0.001, vs. last day of 2 min) until stabilization from sessions 21 to 24. c Progressive ratio responding for alcohol vapor self-administration. ***p < 0.001, vs. non-escalated group. The data are expressed the mean ± SEM of rewards (left y axis) or breakpoint (right y axis). d Increase in BALs in the different phases of the self-administration paradigm. ***p < 0.001, vs. naive; ^##p < 0.01, ^###p < 0.001, vs. 2 min phase. e Somatic withdrawal signs measured 8 h after the last session. Inset overall withdrawal severity (sum of somatic withdrawal scores across the five behavioral signs of alcohol withdrawal). *p < 0.05, **p < 0.01, ***p < 0.001, vs. naive. VLR ventromedial limb retraction, AG abnormal gait, VOC vocalization, TR tail rigidity, BT body tremors