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. 2017 May 30;8:15527. doi: 10.1038/ncomms15527

Figure 5. The inheritance of vulnerability to cocaine reinforcement is contingent on highly motivated cocaine self-administration.

Figure 5

(a) Naive male rats were randomly paired. In each pair, one rat was allowed to actively self-administer cocaine or saline by pressing the lever (SA group), and with each drug infusion by SA group rat, a yoked infusion of exactly the same dose of cocaine or saline (Saline-Yoke) was delivered at the same time passively (without lever press) to the paired rat (Yoke group). The yoked rats corresponding to Saline-SA, Addict-SA and Non-addict-SA groups were designated as Saline-Yoke, Addict-Yoke and Non-addict-Yoke, respectively. (b) Addict-SA F1 rats showed significantly higher lever press and break point for cocaine than Non-addict-SA F1, but there was no difference between Addict-Yoke F1 and Non-addict-Yoke F1. Lever press, Group × Yoke × FR, MMRM, χ2 (4)=35.55, P<0.001; P<0.001, Saline F1 versus Non-addict F1, P<0.001, Non-addict F1 versus Addict F1; FR5, ***P<0.001, Addict-SA F1 versus Non-addict-SA F1, *P=0.013, Addict-SA F1 versus Saline-SA F1, ***P<0.001, Addict-SA F1 versus Addict-Yoke F1; *P=0.038, Addict-Yoke F1 versus Saline-Yoke F1. Break point, two-way ANOVA by Ranks, FGroup × Yoke (2, 91)=3.604, P=0.090; ***P<0.001, Addict-SA F1 versus Non-addict-SA F1, ***P<0.001, Non-addict-SA F1 versus Saline-SA F1, *P=0.041, Addict-SA F1 versus Addict-Yoke F1. Non-addict-SA F1, n=17; Non-addict-Yoke F1, n=9; Addict-SA F1, n=24; Addict-Yoke F1, n=14; Saline-SA F1, n=20; Saline-Yoke F1, n=12. Data are expressed as mean±s.e.m.