Figure 5.

Escalated rate of cocaine intake remains following abstinence. A, Experimental timeline. Rats performed 5 d of cocaine or saline self-administration before a 14 d abstinence period. Both groups were then allowed to self-administer cocaine for 5 d post-abstinence. B, Control rats did not escalate in rate of intake during the saline self-administration period, but did escalate during 5 d of cocaine self-administration after abstinence. Conversely, re-exposure rats escalated during the initial 5 d of self-administration, but did not continue to escalate following the abstinence period. C, Rate of cocaine intake did not differ between the final day of pre-abstinence self-administration and the first day of post-abstinence self-administration in the re-exposure group. *p < 0.05, **p < 0.01 for the slope of the regression line versus zero. Control, n = 5; re-exposure, n = 7. Error bars indicate ± SEM.