Time course of IL-1β (A), TNFβ (B), IL-6 (C), and IFNγ (D) concentrations measured in plasma collected 2, 6, 12, or 24 h after LPS (830 μg/kg) or saline injection. Bars represented the means ± SEM (n= 6). The * symbol represented statistical differences between saline and LPS groups, *p<0.05; **p<0.01; ***p<0.001. Bars labeled with different letters (a, b or c) are significantly different from each other (p<0.05).