Objective:To investigate the effect and mechanism of Qingying decoction on endotoxin fever in rabbits. Method: First

rabbit fever model was established by Escherichia coli endotoxin. Then rabbits were treated with Qing Ying decoction high dose

low dose to observe the animals symptoms and changes of body temperature; and tumor necrosis factor (TNF-α) content in serum

thromboxane B2 (TXB2) and 6-ketone-prostaglandin F1 alpha (6-keto-PGF1α) levels were measured in plasma by radioimmunoassay

and

and plasma tissue plasminogen activator (t-PA)

and tissue plasminogen activator inhibitor (PAI) activity were determined by chromogenic substrate method. Result: Qingying decoction of both high dose group and low dose group had a significant antipyretic effect on endotoxin fever in rabbits (P<0.01)

could markedly inhibit TNF-α

TXB2 levels(P<0.05 or P<0.01) and lower PAI activity (P<0.01)

increase 6-keto-PGF1α content and t-PA activity (P<0.01)in fever rabbits. Conclusion: Qingying decoction has antipyretic circulation effect on endotoxin fever in rabbits. It may play the role of antipyretic circulation by inhibiting the release of pyrogenic cytokines and regulating the secretory function of vascular endothelial cells in febrile rabbits.