Figure 4. Escalation of Fentanyl Self-Administration During 6-hr Sessions.
Mean (±SEM) number of infusions earned in 6-hr self-administration sessions for social-housed males and females given either PT150 or placebo (panel a) and isolate-housed males and females given either PT150 or placebo (panel b). For clarity, data are collapsed across the acute stress treatment, as that factor yielded no significant effect in the statistical model.