Effect of agonist or antagonist of the NMDA receptor on LPS-treated animal’s memory. Immediately after training, the animals were injected with saline or LPS (250 μg/kg, intraperitoneally), 5 min later they were injected with saline or spermine (0.3 mg/kg, intraperitoneally), and 5 minutes after that they were injected with saline or ifenprodil (0.3 mg/kg, intraperitoneally) in different flanks. Ifenprodil reversed the effect of spermine in LPS-treated animals. Data are the mean ± standard error of the mean of 13 to 15 animals per group. *P < 0.05 compared with control group Sal/Sal/Sal, #P < 0.05 compared with LPS/Sal/Sal group (three-way ANOVA followed by the Bonferroni post-hoc test). Ifen, ifenprodil; LPS, lipopolysaccharide; Sal, saline; SPM, spermine.