| Objective:Using the polycystic ovary syndrome(PCOS) rats model induced by letrozole as the study object, to observe the expression of insulin receptor(IR), insulin-like growth factor-1(IGF-1),glucose transporter proteins4(GLUT4) o f endom etr ium in rats with po lycysticov arian syndrome (PCOS),and analyse the correlation between them, and to investigate the effects of metformin on PCOS rats and to analyze the possible mechanism.Methods:Fiftyfive female Wistar rats of six weeks age were randomly divided into model group(40cases) and control group(15cases). Set up an animal model by using the non-steroidal aromatase inhibitor-Letrozole. During this period, vaginal smears were collected daily for estrus cycle determonation. After completing the PCOS rats model, the model group rats were drawed ten randomly, according to vaginal smears results, serum hormone level and ovary tissue polycystic to assess model effect, when the success rates are over80%,the model group remain rats were randomly divided into metformin treatment group(treatment group) and placebo group(PCOS group),fifteen for each group.The treatment group was administered metformin at concentration of270mg/kg p.o.dissolved in distilled water,while PCOS group and control group was administered distilled water p.o., after fourteen days, the level of serum luteinizing hormone(LH), follicle stimulating hormone(FSH), estradiol(E2), testoterone(T) and fasting insulin(FIN) was detected by radioimmunoassay(RIA). The endometrium tissue of every group rats underwent paraffin imbedding, microtome section, HE staining and then observed their pathohistology by lighter microscope. The expression of IR. IGF-1and GLUT4in every group endometrium were detected and evaluated by immunohistochemistry and image analysis system.Results:1. The estrus cycles of model group showed irregular change, which indicating the rats had no ovulation.2. The anatomical morphology of uterus without apparent distinction in each group the average ovary weight of PCOS group is higher than control group and treatment group(P<0.05).Ovary surface is pale, has larger volume and is seen many the saccade expansion follicle.3. Histologic detection of endom etr ium and ovaries: In PCOS group, it can be seen saccular dilatation follicle, the decreased number of corpora lutea. a thin layer of granulosa cells, the puff alignment granulosa cells and a thick layer of theca cells. In treatment group,it can be seen increased granular cell layer, decreased theca cell layer and increased corpora lutea.4. Detection of the serum gonadal hormone level:The values of T and LH in PCOS group are higher than those of the control group(P<0.05), The T and LH in treatment group are lower than those of the PCOS group(P<0.05), The values of E2and FSH in PCOS group are lower than those of the control group(P<0.05). The E2and FSH in treatment group are higher than those of the PCOS group(P<0.05).5. Expression of local regulators in the endometrium:The expression of insulin receptor(IR)proteins and glucose transporter proteins4(GLUT4) of endometrial in PCOS rats were significantly lower(P<0.05)than those in control group, the expression of (IGF-1)protein in PCOS rats was higher than that in control group(P<0.05). The expression of IR and glut4in the treatment group increased(P<0.05), but was still lowerthan that in control group(P>0.05). However, compared with PCOS group, the expression of IGF-1protein in treatment group was decreased(P<0.05), but was stilL higher than that in control group(P>0.05).Conclusions:1. Letrozole-induced model in rats can be served as the ideal model of PCOS.2. The abnormal expression of IR、IGF-1、GLUT4in rats endometrium closely related with PCOS endometrial receptivity3. Metformin could regulate the expression of the IR、IGF-1、GLUT4in rats endom etr ium and the endocrine function to treat PCOS. |
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