WIN55,212-2 prevents the effects of shock and SRs on extinction (Ext). (a) On Ext1, the shock groups (shock–no SR, shock–SR) demonstrated increased latency compared with the no-shock groups. On Ext2–4, the shock–SR group demonstrated increased latency compared with all groups (*p<0.05; **p<0.01; ***p<0.001). (b) When WIN55,212-2 was injected 2 h after the shock, the shock–SR Veh group showed increased latency compared with the shock–no SR WIN group on Ext2. On Ext3 and 4, the shock–SR Veh group showed increased latency compared with all groups (*p<0.05; **p<0.01; ***p<0.001). (c) When the antagonist AM251 was injected, no significant differences were observed between the groups. (d) The shock–SR group demonstrated increased latency to enter the dark side on Ext3 and 4, compared with the shock–no SR group and with rats exposed to shock and placed on the EP on days 3 and 5 after the shock (shock–EP; *p<0.05). (e) Rats were injected with sertraline once (shock–SR SH1) or once daily for 7 days (shock–SR SH7). The shock–SR WIN group demonstrated reduced latency compared with the shock–SR Veh and shock–SR SH1 groups on Ext2, Ext3, and Ext 4. On Ext3, the WIN group also demonstrated increased latency compared with the SH7 group. The SH7 group demonstrated reduced latency compared with the Veh (p<0.001) and SH1 (p<0.05) groups on Ext3 and compared with the Veh group on Ext4 (*p<0.05; **p<0.01; ***p<0.001).