Objective: To observe the effects of total saponins of Chaenomeles speciosa (TSCS) on synovial pathology

synovial mast cell degranulation and tryptase expression and to investigate the relationship between the functions of mast cells and effects of TSCS on adjuvant arthritis(AA) in rats. Method: Male Wistar rats were randomly divided into normal control group

model group and TSCS group(200 mg·kg-1)

n=15 in each group. AA was induced by injection of 0.1 mL Freund's complete adjuvant in left hind limb footpad. Normal control group and model group received saline treatment

while rats in the TSCS group were treated once a day for 21 days. The body weight and paw volume of the rats were measured every six days. Synovial tissues of the right hind ankles were sampled and stained with HE for observing synovial pathology to evaluate the effects of TSCS on AA

then stained with TB for observing the number and degranulation ratio of synovial mast cells and finally detected by immunohistochemical staining method to investigate the expression of tryptase in synovium. Result: TSCS increased significantly the body weight of AA rats

while decreased obviously the paw volume. TSCS significantly inhibited inflammatory cell infiltration

synovial cell hyperplasia

and synovial fibroplasia in synovium of AA rats. TSCS could significantly diminish the numbers of total and degranulated mast cells in AA rats

TSCS decreased the expression of tryptase in synovium. Analyzed by Spearman's bivariate correlation

the number of mast cells and degranulation ratio of mast cells were positively correlated with the pathological scores. Conclusion: TSCS can improve pathological condition of inflammatory synovium in AA rats by inhibiting the function of synovial mast cells

which may play an important underlying role in the immunoregulation of TSCS on AA.