4.15. LPS-Induced Endotoxemia

ICR mice were intraperitoneally (i.p.) administered with SM in 10% Tween-80 at the dose of 50 mg/kg and vehicle (10% Tween-80) 1 h prior to endotoxemia induction by LPS (055:B5, Sigma-Aldrich, USA) i.p. at a dose of 5 mg/kg (non-lethal endotoxemia) or 20 mg/kg (lethal endotoxemia). We used SM at a dose of 50 mg/kg, since in our previous work [73] for the evaluation of anti-inflammatory activity of SM on the models of carrageenan- and histamine-induced paw edema, we found out that the dose of 50 mg/kg is the maximum possible dose for SM that can be administered in mice without significant toxicity. Blood samples were collected from the retro-orbital sinus 4 h after LPS injection at a dose of 5 mg/kg. Blood serum was prepared by a standard protocol, and the pro-inflammatory cytokines TNF-α and IL-6 were measured by a mouse TNF-α ELISA kit and a mouse IL-6 ELISA kit (Thermo Scientific, Rockford, IL, USA) according the manufacturer’s instructions. The survival rates were evaluated after LPS injection at the dose of 20 mg/kg. The mortality of mice was assessed every 12 h for 7 days. SM- and vehicle-treated mice without LPS challenge were used as controls. In both experiments, dexamethasone at the dose of 0.5 mg/kg (non-lethal endotoxemia) and 1 mg/kg (lethal endotoxemia) was used as a reference drug with proven anti-inflammatory activity.