Objective:To investigate the influence of bacterial lipopolysaccharides on SWDs on ECoG in rats following γ-Butyrolactone-induced absence seizures, and speculate on its possible mechanism. Method:Forty adult SD rats were randomly divided into four groups, intraperitoneally and injected with 50 μg/kg, 100 mg/kg, and 200 μg/kg of LPS, and 1 ml of saline respectively. One hour later, five rats randomly selected from each group were sacrificed and changes of IL-1βmRNA in the hippocampi were detected by RT-PCR, while the other five rats were intraperitoneally injected with 200 μg/kg of GBL to induce absence seizures and variations of latency and endurance time of SWD on ECG were recorded. Results:The expression of IL-1βmRNA in the hippocampi of rats one hour after intraperitoneal injection in the 50μg/kg group was 0.196 ± 0.04, while in the 100 μg/kg and 200 μg/kg group was 0.285 ± 0.057 and 0.404 ± 0.072,respectively, all significantly different from the control group, which was 0.131 ± 0.034(P < 0.05). Besides, The SWDs latency time of discharge in absence seizure rats in the experiment groups was significantly shorter than that of the control group, while the duration time was longer(P < 0.05). Though the latency time the 50 -滋g/kg and 100 -滋g/mg group was shorter while the durance time longer compared with that of the 50 -滋g/kg group(P < 0.05), there was no significant difference in the 50 -滋g/kg and 100 -滋g/kg group(P > 0.05). Conclusion:LPS could affect the SWDs of GBL-induced absence seizure in rats by shortening the latency time and elongating the duration time with dose dependence and saturation, the mechanism of which is probably related to the abnormal immunity stimulated by LPS.