Apocynin treatment prevents cognitive impairment after sepsis. Septic encephalopathy was induced in WT mice (n = 5 to 10/group) via intraperitoneal inoculation with fecal slurry. The control group was injected with saline (0.9%). Mice were divided into two groups and treated with apocynin (5 mg/kg body weight) one hour after feces injection and every 24 hours for 3 days. All the animals received imipenem (10 mg/kg body weight) six hours after infection and every 24 hours for 3 days. (A) Step-down inhibitory avoidance test. Aversive memory was tested 24 hours after training by recording the latency time on the platform (with a cut-off of 180 seconds). Data are expressed as individual values and horizontal lines represent the mean latency in seconds; significant differences were found between sham versus septic mice (Mann–Whitney U-test, *P < 0.05). Spatial memory impairment was evaluated with the Morris water maze. (B) Time to find the platform. Student t-test, *P < 0.05. (C) Trial in the absence of platform. Latency represents the exploration on the quadrant where the platform was before removal. Student t-test, *P < 0.05.