The Expression And Significance Of Gnrh Recepter In Mifepristone Reduced Pcos Rats' Pituitary

Objectives1. To establish an animal model for the study of polycystic ovarian syndrome by using mifepristone.2. To determine GnRH receptor in pituitary in PCOS rats and the control group, to explore whether it plays roles in the etiology of PCOS.Methods4-day-cyclic female Sprague-Dawley(SD) rats were randomly divided into two groups. The control group received injection (s.c.) of oil 0.1ml/100g body weight, while the experimental group received injection of mifepristone 2mg/100g body weight (in 20:1 soluble in oil injection), over 8 consecutive days beginning on the first day of estrus and take of vaginal smears each day. In the ninth day, measured the weight of rats and ovaries, serum T,LH,FSH,E2; ovarian morphological changes were observed under the microscope; the expression of GnRH receptor in pituitary were measured by immunohistochemistry.Results1. The estrus cycles of mifepristone treated group showed irregular change at the forth day,which indicated that the rats had no ovulation. 2. Changes in body weight before and after treatment and the ovaries weight were significantly increased compared with the control group(△body weight:22.2±4.808 VS 11.3±2.697(g);ovaries weight:53.867±1.571 VS 43.435±2.670(mg/100g body weight))(P<0.01). The levels of T,LH and E2 in the experiment group were significantly higher than in control group(serum T:0.492±0.095 VS 0.201±0.042(ng/ml);serum LH: 15.571±2.119 VS 10.305±1.678(mIU/ml);serum E2:78.850±6.343 VS 71.450±4.146(pg/ml)) (P<0.01),while the level of FSH was lower, but there is no significance (7.592±0.899 VS 8.194±1.281 (mIU/ml))(P=0.094) .3. In experiment group , can see multiple follicular cysts and atretic follicles, the granule cells layer reduced to 2-3 layers, and the oocytes or corona radiata disappeared. It is also seen the decreased number of corpora lutea with incomplete luteinization. The control group can be seen more complete corpora lutea and different levels of follicles with thicken layer of granulosa cells.4. The expression of GnRH-R exists in pituitary in both group , and in experimental group, the expression of GnRH-R in pituitary was significantly higher(the value of average optical density : 117.151±6.817 VS 96.315±6.894,P<0.05).5. the serum T and LH levels were positively correlated with the expression of GnRH-R in pituitary.(r1=0.891,r2= 0.801,P<0.05).Conclusions1.The morphologic and hormonal changes of the ovaries in the mifepristone induced PCOS models were similar to those of the patients with PCOS.It was proved to be an ideal PCOS animal model.2.The increased GnRH-R expression might have some relevance with the elevated testosterone and LH and anovulation.