[Animal modeling] - Construction and evaluation of two models of obese polycystic ovary syndrome with insulin resistance in rats

  Objective To establish an animal model of obese polycystic ovary syndrome (PCOS) with insulin resistance by two different ways combined with high-fat diet, and compare its endocrine and metabolic characteristics.

  Methods The rats were randomly divided into 3 groups: control group, which were given normal diet and purified water; Letrozole group was given letrozole (1 mg/kg) by gavage, HCG+INS group was given chorionic gonadotropin and insulin (HCG+INS) by subcutaneous injection, and both groups were fed with high-fat diet and 5% glucose solution. Gram staining was used to observe the changes of two estrous cycles; On the 23rd and 30th days, the wet weights of uterus and ovary were measured; Histopathological changes of ovary were observed by hematoxylin eosin (HE) staining; Fasting blood glucose (FBG), blood lipid (TG) and total cholesterol (TC) were measured by blood biochemical analyzer; Determination of sex hormones (follicle stimulating hormone FSH, luteinizing hormone (LH), estradiol (E2), total testosterone (T) and serum inflammatory factor tumor necrosis factor) by enzyme-linked immunosorbent assay (ELISA)- α (TNF- α) And interleukin-1 β (IL-1 β)) Horizontal change; The insulin resistance index HOMA-IR was calculated; Determination of ovarian TNF by real-time fluorescent quantitative PCR- α And IL-1 β MRNA changes.

  Results Compared with the control group, Letrozole group and HCG+INS group had disorder in two estrous cycles, but HCG+INS group had occasional ovulation; On the 23rd day, the uterus wet weight and E2 level in the Letrozole group decreased significantly, the ovary wet weight, INS, HOMA-IR, TG, TC level increased significantly, the levels of INS, HOMA-IR, TC, TG, LH in the HCG+INS group increased significantly, and the E2 level decreased significantly (P<0.05, P<0.01). On the 30th day, the levels of FBG, INS, HOMA-IR, TG, FSH, LH and serum TNF in the two groups- α And IL-1 β The level and ovarian mRNA were significantly increased. At the same time, obesity, anovulation, hyperandrogenism, polycystic ovarian changes and other characteristics were more obvious in the Letrozole group.

  Conclusion Both methods can successfully induce PCOS-IR animal models, and the changes of body weight, endocrine and metabolic indexes of letrozole on the 30th day are more consistent with the pathological characteristics of Hefei obese PCOS-IR.