ObjectiveTo evaluate the antipyretic effect of the Qingwen Baiduling prescription in a dry yeast-induced rat fever model and to investigate its antipyretic mechanism， providing a theoretical basis for its clinical application.MethodsSPF-grade male SD rats were randomly assigned to six groups （n=6 per group）： control， model， aspirin （20 mg·kg^-1）， and high-， medium-， and low-dose Qingwen Baiduling prescription groups （14.40， 7.20， 3.60 g·kg^-1）. The fever model was established by subcutaneous injection of dry yeast suspension on the back. After model induction， body temperature was recorded every 1 hour. Drugs were administered at 6 hours after modeling， and body temperature was continuously recorded hourly for 12 hours. Record the body temperature of rats to observe the trend of changes in body temperature. Serum interleukin-6 （IL-6）， interleukin-1β （IL-1β）， and tumor necrosis factor-α （TNF-α） levels， as well as hypothalamic prostaglandin E₂ （PGE₂） and cyclic adenosine monophosphate （cAMP）， were measured using enzyme-linked immunosorbent assay （ELISA）. Hypothalamic tissue morphology was examined by hematoxylin and eosin （HE） staining. Western blot was used to detect hypothalamic expression of Toll-like receptor 4 （TLR4）， myeloid differentiation factor 88 （MyD88）， nuclear factor-κB p65 （NF-κB p65）， inhibitor κBα （IκBα）， phosphorylated IκBα （p-IκBα）， IκB kinase α （IKKα）， IKKβ， phosphorylated IKKα/β （p-IKKα/β）， and cyclooxygenase-2 （COX2）.ResultsCompared with the control group， the model group showed a significant increase in body temperature 6 hours after modeling （P0.01）， confirming successful fever induction. Serum IL-6， IL-1β， TNF-α， and hypothalamic cAMP and PGE₂ levels were significantly elevated （P0.01）. Hypothalamic neurons exhibited irregular morphology and disordered distribution， accompanied by inflammatory cell infiltration and microglial aggregation. Expression levels of TLR4/NF-κB pathway-related proteins and phosphorylated proteins were significantly increased （P0.05， P0.01）. Compared with the model group， 2-3 hours after administration， all Qingwen Baiduling prescription dose groups significantly reduced body temperature （P0.01）. All dose groups significantly decreased serum IL-6， IL-1β， TNF-α， and hypothalamic cAMP and PGE₂ levels （P0.05， P0.01）. Neuronal morphology was markedly improved in the high- and medium-dose groups， with narrowed intercellular spaces and reduced inflammatory infiltration. The prescription effectively inhibited hypothalamic expression of TLR4， MyD88， NF-κB p65， p-IκBα， p-IKKα/β， and COX2 proteins （P0.05， P0.01）.ConclusionQingwen Baiduling prescription effectively reduces body temperature in rats by mitigating the further effects of inflammatory cytokines on the hypothalamic thermoregulatory center through the blood-brain barrier. Its antipyretic mechanism may be related to inhibition of NF-κB pathway activation.

Qingwen Baiduling prescription;Yinqiao powder;Chaige Jieji decoction;dry yeast;antipyretic effect and mechanism