MK-801 injection (0.1 mg/ml, i.p.) impaired freezing in the post-reactivation long-term memory test (PR-LTM) in rats infused with vehicle prior to (A) or immediately after (B) memory reactivation. While pre-reactivation infusion of SR141716A (8 μg/μl) did not alter the amnestic effect of MK-801 (C), post-reactivation SR141716A prevented the MK-801-induced impairment in freezing at PR-LTM (D). Statistical analyses confirmed a selective effect in the post-reactivation SR141716A condition (Timing x Infusion x Injection: F(1,41) = 5.19, p = 0.028, η2p = 0.11). No effect of MK-801 injection or SR141716A infusion was observed in the post-reactivation short-term memory test (PR-STM). Data are presented as individual units and mean. n = 6 for all pre-reactivation groups, 6 for post-reactivation Saline, 5 for post-reactivation MK-801 and 7 for post-reactivation SR141716 + Saline and SR141716 + MK-801.