Fig. 1.

BALB/cJ (J) mice show enhanced state-dependent learning of OXY-CPP (1.25 mg/kg, i.p.) and concomitant locomotion compared with BALB/cByJ (By) mice. (A) Schematic of the CPP regimen and apparatus. (B) Results were analyzed using a three-way ANOVA considering substrain, treatment, and sex; error bars represent standard deviation. There was a treatment × substrain interaction (P = 0.048) that was explained by J mice showing greater OXY-CPP than By mice (Tukey’s post hoc *P = 0.015). (C) Female mice accounted for a majority of the substrain difference in OXY-CPP. (D) For total OXY-induced locomotor activity, there was a significant treatment × substrain interaction (P = 0.043) that was explained by J mice showing greater OXY-induced locomotion than By mice (Tukey’s post hoc *P = 0.037). (E) Females accounted for a majority of the substrain difference in total OXY-induced locomotor activity. (F) For OXY-induced locomotor activity specifically on the OXY-paired side (right side), there was a significant treatment × substrain interaction (P = 0.043) that was explained by J mice showing greater OXY-induced locomotor activity than By mice (Tukey’s post hoc *P = 0.037). (G) When sex was included in the ANOVA model, there was a significant treatment × substrain × sex interaction (P = 0.035) that was driven by increased OXY-induced locomotor activity in J females compared with By females (Tukey’s post hoc *P = 2.3e-5). Sample sizes from left to right (panel B) were 32, 37, 36, 32, 29, 38, 37, and 43.

# = main effect of treatment p<0.05, * = Tukey's Post Hoc T-test p < 0.05.