Figure 4.

Rats with a history of long-access WIN55,212-2 self-administration during adolescence demonstrate cue-induced reinstatement of drug-seeking. (a) WIN SA rats were extinguished on response-contingent drug administration during 1-h sessions for 1 week. Active lever presses reduced to similar numbers as inactive lever presses. (b) Relapse of drug-seeking behavior was tested 1 and 21 days later (corresponding to 8 and 29 days of abstinence). Rats significantly increased responding on day 8, indicating reinstatement of drug-seeking behavior; and this effect was magnified when rats were tested on day 29 of abstinence, indicating an incubation of craving. (c) Total number of lever presses for the last day of extinction (abstinence day 7; 1-h session), day 8 of abstinence (30-min session) and day 29 of abstinence (30-min session). Rats had a significant increase in responding from abstinence day 8–29, and the lack of difference between the last day of extinction and day 8 of abstinence is due to the difference in session length. Values show group means±SEM; ***p<0.001, **p<0.01, *p<0.05.