Abstract: AIM: To investigate the antipyretic mechanisms of the chuanhuning injection in rats. METHODS: The fever model was made by suspension of yeast which was injected hypodermically to the rats.The contents of PGE₂ and cAMP in hypothalamus were measured by radioisotope method.RESULTS: The maximal increment in body temperature (ΔT) and 6 h thermal response index(TRI6) in the model group were significantly higher than those in the control group (P <0.01), ΔT in chuanhuning 125 mg·kg^-1group and 250 mg·kg^-1group and TRI6 in chuanhuning 250 mg·kg^-1group were lower than those in the model group(P <0.01), and ΔT and TRI6 in chuanhuning 250 mg·kg^-1group were lower than those in chuanhuning 125 mg·kg^-1group (P <0.01). The contents of PGE₂ and cAMP in hypothalamus in model group were more higher than those in the control group (P <0.01), the contents of PGE₂ and cAMP in the chuanhuning groups were lower than those in the model group (P <0.01), and the contents of PGE₂ and cAMP in chuanhuning 250mg·kg^-1group were lower than those in chuanhuning 125 mg·kg^-1group (P <0.05).ΔT is positively correlative with the contents of PGE₂ and cAMP in hypothalamus (P <0.01).CONCLUSION: The antipyretic mechanisms of chuanhuning injection may be related to its decreasing the contents of PGE₂ and cAMP in hypothalamus, and the effects are dosage-dependence.

Key words: chuanhuning injection, fever, hypothalamus, PGE₂, cAMP