Experimental protocol. In all the experiments, rats were fasted for 12 h before administration of LPS and food was returned thereafter. A 20 mg/ml solution of AMD was made in its vehicle (0.18% Tween 80), and 4.1 3 10 5 EU/ml solution of LPS was made in sterile saline. To determine the optimal time interval between AMD and LPS treatments, rats were treated with AMD (300 mg/kg, ip) 2 h, 8 h, 12 h, 16 h, or 20 h before LPS (1.6 3 10 6 EU/kg, iv). For the evaluation of the dose-response relationship for AMD, rats were treated with AMD (0-400 mg/kg, ip) and 16 h later with LPS (1.6 3 10 6 EU/kg, iv) or saline. For the evaluation of the dose-response relationship for LPS, rats were treated with AMD (400 mg/kg, ip) or vehicle and 16 h later with LPS (0-1.6 3 10 6 EU/kg, iv). In subsequent studies, rats were treated with AMD (400 mg/kg, ip) or vehicle and 16 h later with LPS (1.6 3 10 6 EU/kg, iv) or saline. In the etanercept treatment study, rats were treated with etanercept (8 mg/kg) or sterile water by sc injection 1 h before LPS.