Heroin seeking in females versus males. (A) Heroin seeking over the course of heroin self-administration, extinction, and cued reinstatement in female and male rats (Charles River Laboratories). n = 7/group (n = 1 catheter failure/group eliminated). Sidak's post-hoc active versus inactive lever (*) P < 0.05 females, (+) P < 0.05 males. (B) Number of heroin infusions consumed in females and males over the course of self-administration. (C) Heroin seeking on the first day of extinction was higher in females. Sidak's post-hoc males versus females (*) P < 0.05. (D) The extinction index did not differ between sexes. (E) Females relapsed at higher rates on the cued reinstatement test. Sidak's post-hoc males versus females (**) P < 0.0001. (F) Heroin seeking on extinction day 1 correlated with cued relapse rates in females, but not males. All data are mean ± SEM, except data from individual rats shown in (F). Gray bars = inactive presses nested within active presses.
