Objective: To verify the objective existence and synergistic effect of key herbs by researching the effect of Cimicifugae Rhizoma and Bupleuri Radix combination in Buzhong Yiqi Tang on spleen deficiency mice. Method: Ninety mice were randomly divided into the control group (CG)

the model group (MG)

the positive control group (mosapride

1.93×10-3 g · kg-1) (PCG)

Buzhong Yiqi Tang group (BZYQTG

8.58 g · kg-1)

BZYQT minus of Danggui Chenpi decoction group (MDCDG

7.41 g · kg-1)

BZYQD minus of Shengma Chaihu decoction group (MSCDG

7.02 g ·kg-1)

Shengma Chaihu decoction group (SCDG

1.56 g · kg-1)

MSCD plus of Qianghuo Duhuo and Fangfeng decoction group (PQDFDG

10.53 g · kg-1)

MSCD plus of Gegen decoction group (PGDG

8.32 g · kg-1) of 10 rats each. Except the mice in the normal group

the other mice were induced by a compounding method-administration of Rhubarb decoction

exhaustive swimming and starvation to a spleen deficiency model. After intragastic administration for 7 days

the anti-fatigue functions and other effects including spleen index

thymus index and gastrointestinal propulsion of mice were observed. Result: The swimming time

spleen and thymus weight and small intestinal propulsion rate of MG mice were significantly lower than those of the normal group (P<0.01). The swimming time

thymus weight and the rate of intestinal propulsion had no significant difference between SCDG and MG mice

while the swimming time and small intestinal propulsion rate were higher in other groups than those in MG (P<0.01). The swimming time was significantly longer in BZYQTG mice than PCG (P<0.05)

while the results of weight of the spleen and thymus gland

and the intestinal propulsion rate had no significant difference between two groups. The swimming time

spleen and thymus weight and the rate of intestinal propulsion in the prescription drug groups were significantly lower than BZYQTG (P<0.01). The swimming time and the rate of intestinal propulsion were significantly lower in MSCDG than MDCDG (P<0.01

P<0.05). Conclusion: The key herbs of Cimicifugae Rhizoma and Bupleuri Radix combination in BZYQT had more contribution on anti-fatigue effect

improving immune function and gastrointestinal propulsive effect than other adjuvants

which proved that the key synergistic effect of the key herbs. The key herbs of Shengma and Chaihu combination in BZYQT cannot be replaced by Notopterygii Rhizoma

Anoelicae Pubescentis Radix

saposhnikoviae Radix and Puerariae Labatae Radix

which proved that the best compatibility of the drug. This study verified that the key herbs in some formulas are objective existence from the point of view of experimental research.