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

Figure 4. Non-contingent chronic cocaine injections induce inter-generational cocaine resistance.

Figure 4

(a) Rats received 15 mg kg−1 cocaine (Cocaine-IP F0) or equal volume of saline (Saline-IP F0) intraperitoneal injections twice daily for 7 days and were mated with naive females one day after the last injection. Four litters from each of group were randomly designated for behavioural experiment or for mating to generate F2. (b) Cocaine-IP F1 did not show an increase but displayed a decrease tendency in lever press and break point for cocaine in self-administration test, compared with Saline-IP F1 rats. Lever press, Group × FR, MMRM, χ2 (2)=13.00, P=0.0015; FR5, **P=0.009, Saline-IP F1 versus Cocaine-IP F1. Break point, Mann–Whitney Rank-Sum Test, Z=1.060, P=0.289. Saline-IP F1, n=8; Cocaine-IP F1, n=8. (c) There was no statistical difference in lever press or break point between Saline-IP F2 and Cocaine-IP F2. Lever press, Group × FR, MMRM, χ2 (2)=2.60, P=0.272. Break point, Mann–Whitney Rank-Sum Test, Z=0.638, P=0.526. Saline-IP F2, n=8; Cocaine-IP F2, n=8.