OBJECTIVE: To study the regulation role of with neutral property to cAMP-PKA pathway in the rats with cold and heat blood stasis syndromes and it's mechanism. METHODS: 60 rats were randomly divided into normal control group, model control group, Semen Persicae group, radix salvia miltiorrhiza group, rhizoma chuanxiong group, 12 rats per group. The three herb groups were orally given relative herbs decoction, whose dosages were equal to 10 times the human clinical dose, normal and model control groups were orally given water, 2 times/day, 20 mL/kg, for 7 days. Experiments in rats with cold and heat blood stasis syndromes were carried on respectiverly. In heat blood stasis syndromes, except normal control group, the other groups were intraperitoneally injected 10% carrageenan, 5 mL/kg, 1 times/day, for 3 days;24 hours after the last injection, subcutaneously injected 20% dry yeast suspension, 10 mL/kg. In cold blood stasis syndromes, except normal control group, the other groups were put into fridge, temperature--(18 +/- 2) degrees C, 2 hours/ times, 2 times/day, for 7 days. Separately draw 5 ml abdominal aortic blood and taken abdominal aorta, 6 hours and 12 hours after finishing the model in the two syndromes. Tested the cAMP content by elisa, tested the PKA protein expression by Western blot. RESULTS: Semen Persicae with neutral property, could decrease the content of cAMP in plasma (P < 0.01), inhibit the expression of protein PKA (P < 0.05) in rats with heat stagnation and blood stasis syndrome, increase the plasma content of cAMP (P < 0.01) and increase the expression of protein PKA (P < 0.01) in rats with cold stagnation and blood stasis syndrome. Semen Persicae had two-way adjustment action on CAMP-PKA signal pathway. CONCLUSION: In different internal environment of heat stagnation and blood stasis syndrome, cold stagnation and blood stasis syndrome, Semen Persicae with neutral property has two-way adjustment to cAMP-PKA signaling channel, which may be one of the mechanism of it's two-way application.