Letrozole-Induced PCOS Rat Model

Five of the 20 rats were randomly selected as the normal control group (oral administration of 1 mL normal saline for 28 days), and the remaining 15 rats were used to induce the PCOS model by giving 1 mg/kg Letrozole for 21 consecutive days [16 (link)]. After successful PCOS induction, 15 PCOS rats were randomly and equally divided into three groups: the PCOS group (oral administration of 1 mL saline for 28 days), the MET group (oral administration of 1 mL saline dissolved with 500 mg/kg metformin for 28 days) [16 (link)] and the SI group (oral administration of 1 mL saline dissolved with 100 mg/kg soy isoflavones for 28 days) [14 (link)]. The body weight of rats in each group was measured weekly for the duration of the study. After the 7^th week (Day 49), the rats were sacrificed to measure the weight and the ovary of each rat was removed for weighing and measuring long and short diameters. And then the ovarian volume [mm³ = (π/6)*long (mm)*short (mm)²] was calculated as described by Wang [17 (link)]. Additionally, samples of ovarian and vaginal tissues and serum were collected for subsequent index detection. Letrozole was purchased from Jiangsu Hengrui Medicine Co., Ltd.; SI were purchased from Xi’an Tianfeng Biotechnology Co., Ltd.; and metformin was provided by Bristol-Myers Squibb Company.