Objective: To explore the intervention effect and the underlying mechanism of modified Shaoyao Gancaotang on polycystic ovary syndrome (PCOS) in rats.Method: SD female rats were randomly divided into normal group

model group

low

middle and high-dose modified Shaoyao Gancaotang groups (12.5

25.0

50.0 g · kg-1 · d-1) and Diane-35 group (0.001 g · kg-1 · d-1)

with 6 rats in each group. The rats in normal group received distilled water

while all of the other rats were treated with letrozole (0.001 g · kg-1 · d-1) for 21 days to induce the PCOS model. Diane-35 and different concentrations of modified Shaoyao Gancaotang were given by gavage for two weeks after modeling

and the equal volume of distilled water was given by gavage to normal group and model group. After treatment with drugs

the estrus cycle was determined by vaginal smears

the morphological changes were inspected by ovarian biopsy

the serum hormone level was evaluated by enzyme-linked immunosorbent assay (ELISA)

and the protein expression of aquaporin-9 (AQP-9) was detected by Western blot technique.Result: Model group showed an irregular estrous cycle with increased body weight and ovarian weight; the ovaries showed plenty of cystic dilating follicles as well as fewer granulosa cells

without oocyte and corona radiating in the follicles; the serum levels of androgen and luteinizing hormone of PCOS rats were significantly increased (P<0.05)

whereas the levels of estrogen and progesterone were significantly decreased (P<0.05). Compared with model group

modified Shaoyao Gancaotang groups showed decreased body weight and ovarian weight in a dose-dependent manner; serum levels of androgen and luteinizing hormone reduced

whereas the serum levels of estrogen and progesterone were increased. Moreover

modified Shaoyao Gancaotang was associated with AQP-9 expression in ovaries.Conclusion: Modified Shaoyao Gancaotang could intervene polycystic ovaries and hyperandrogenism in PCOS rats

and the underlying mechanism may be correlated with the up-regulation of AQP-9 expression in granulosa cells.