Objective: To investigate the influence of Gegen decoction (GGD) and the potential mechanism on primary dysmenorrhea with cold-damp coagulation induced byoxytocin and cold simulating. Method: Seventy female ICR mice were randomly divided into seven groups:normal group

model group

buprofen group

Guizhi Fuling capsule group

low-dose GGD group

middle-dose GGD group and high-dose GGD group. Subcutaneous injection of estrogen and cold stimulation were used for 3 consecutive days

and peritoneal injection of oxytocin on the 4th day to construct primary dysmenorrhea model with cold-damp coagulation

the writhing response and the levels of nitric oxide (NO) and calcium ion(Ca2+) in mice uterine tissue were investigated. Meanwhile

ibuprofen group received ibuprofen (0.12 g · kg-1)

GFC group received Guizhi Fuling Capsule (1.12 g · kg-1)

GGD group received GGD (low-dose

3.5 g · kg-1;middle-dose

7.0 g · kg-1;high-dose

14.0 g · kg-1). Result: GGD could inhibit the writhing response effectively (the inhibition rate was 81.03%

84.14%

90.15% at low

middle and high-dose

respectively) and increase NO levels and reduce Ca2+ concentration in uterine tissue of mice (P<0.001). The efficacy of GGD was equal to the positive drug ibuprofen and Guizhi Fuling capsule. Conclusion: GGD could effectively alleviate the spasm of uterine smooth induced by oxytocin and cold. The mechanism might be relative to regulation of uterine NO and Ca2+ levels.