Since the arousal and cognition are considered to be maintained by the network oscillation generated by neural circuits in the anterior cingulate cortex (ACC), and are deeply influenced by histaminergic system and disturbed under the systemic inflammation, it is expected that elevated inflammatory cytokines would alter ACC network oscillations along with the behavioral changes. We studied the effects of lipopolysaccharide (LPS) on ACC-related task and kainic acid (KA) -induced network oscillations in an ACC slice, to search the relationship among LPS-induced elevation of cytokine level, the profiles of behavior and network oscillations.
<Materials & Methods> Male C57BL/6J mice were intraperitoneally administered with LPS (30 µg/kg). Three hours later, novel object recognition test (NOR) was performed, followed by preparations of blood and cortical tissue samples, and brain slices containing ACC for electrophysiology. 
<Results> LPS treatment significantly increased serum IL-6 level and tended to increase brain tissue IL-6 level. Network oscillation was evoked by KA (0.3-3 µM) perfusion alone or with histamine (10 µM) as field potential activities within the ACC in vitro. Power of KA-induced oscillation increased in the LPS group compared with the control. Histamine enhanced oscillation power in the control group, but this was not observed in the LPS group. In the NOR, exploration time for a novel object decreased in the LPS group but without a significant difference in the recognition index between the two groups.