Expression Of Insulin And Insulin-like Growth Factor-1 In Polycystic Ovary Syndrome Rat Model

Objective:In this study, polycystic ovary syndrome rat model was made using Bogovich method. Oral glucose tolerance test and insulin releasing test were measured. The alteration of light microscope and electron microscope of hypothalamus, pituitary and ovary was observed. The localization of insulin-like growth factor-1(IGF-1)was determined in hypothalamus, pituitary and ovary using immunohistochemical staining. The aim was to investigate polycystic ovary syndrome rat model whether has insulin resistance or not and the role of hypothalamus, pituitary and ovary in PCOS pathology. Materials and methods:24-day-old immature female SD rats (n=36) were separated into two equal groups at random. One group was created PCOS animal model, another group was used as control. Being 36 days old, the rats were measured insulin and glucose with oral glucose tolerance test. After 4% Chloral Hydrate(400mg/kg)was injected in abdominal cavity for anesthesia, cardiac ventricle was perfusion. Hypothalamus, pituitary and ovary were obtained for immunohistochemical staining. Three rats for each group were fixed for transmission electron microscopeanalysis. Location of arcuate nucleus was based on Paxins' the rat brain. The levels of INS in serum were measured by RIA. A Guinea pig polyclonal antibody (made in Shanghai biological substance Institution) against human INS labelled by 125I was used as the primary antibody. The sensitivity and specificity were high. Blood glucose was measured by Precision Plus test paper made by abbott laboratory in USA. A rabbit monoclonal antibody against rat IGF-1 (SANTA CRUZ Company, USA. 0.1ml, Diluted 1:200 before use) was used as the primary antibody in immunohistochemical staining.The intensity of immunostaining was evaluated by repeated staining of the same specimens and by more than two observers respectively. The primary antibodies to IGF-1 were replaced by PBS solution as the negative controls. Buffy drops in cells were regarded as the positive staining. Five sights were selected in 400× sight at random, and positive cells/all cells ratio were counted. It was graded as (－) for ＜10%, (＋) for 10~33%, (＋＋) for 33~66%, and (＋＋＋) for ＞66%.Statistics: RIA results were expressed as mean±SE. Comparison between groups was undertaken using paired t-tests. The ???analysis was used to compare results obtained from IH. All data were analyzed with the SPSS statistical program. P＜0.05 was defined as statistically significant.Results:1 There were no difference of body weight between PCOS rats and normal rats. 2 External appearance: the ovaries of PCOS rats were obviously enlargement with many vesicles. The ovary weight of PCOS rats were significantly higher than those of normal rats(P＜0.01). There was no difference of appearance between hypothalamus and pituitary in naked eye.3 Oral glucose tolerance test and insulin releasing test: the levels of insulin after oral glucose 60min and 120min in PCOS rats were significantly higher than those in normal rats, P＜0.01. Insulin sensitive rate(INS/GC) after oral glucose 60min and 120min in PCOS rats was significantly higher than those in normal rats, P＜0.01. PCOS rats had insulin resistance(IR). The 60min INS means of PCOS group and normal group were 22.808±2.655 and 17.683±3.015 respectively. The 120min INS means of PCOS group and normal group were 17.647±3.301 and 12.828±2.996 respectively. The 60min INS/GC means of PCOS group and normal group were 3.03±0.38 and 2.35±0.46 respectively. The 120min INS/GC means of PCOS group and normal group were 2.63±0.42 and 1.98±0.44 respectively.The alteration of light microscope and electron microscope of hypothalamus, pituitary and ovary was al4 following.4.1 The differentiation between arcuate nucleus of PCOS rats with normal rats was not clear in light microscope .The form characters of arcuate nucleus GnRH neur of PCOS rats hypothalamus in electron microscope were as following: the nucleus of GnRH neur of PCOS rats were more bigger and...