| Objective: To study the changes of Kisspeptin expression in hypothalamus of rats with polycystic ovary syndrome,observe the effects of metformin on endocrine reproductive system and Kisspeptin expression in hypothalamus of rats with polycystic ovary syndrome,and explore the possible mechanism of metformin in the treatment of rats with polycystic ovary syndrome.Methods:(1)Thirty-four female rats aged 5-6 weeks old with a body weight of about 170 g SPF-level SD(Sprague-Dawley)were randomly divided into blank group(n=14)and model group(n=20).The blank group was feeded with normal saline and the model group was continuously gavaged with letrozole and recording the estrous cycle of rats.After 28 days,6 rat ovarian tissues were randomly taken from the blank group and the model group and the histomorphological changes were observed by HE staining to evaluate the modeling effect.(2)The remaining rats in the blank group were divided into normal saline group(n=6),and the rats in the remaining model group were randomly divided into metformin group(n=6)and letrozole group(n=6).Metformin gavage(metformin 300mg·kg-1·d-1,dissolved in normal saline)was used in metformin group for 21 consecutive days of gavage and the same amount of normal saline was given to the normal saline group and letrozole group for 21 days and the rat estrus cycle was recorded at the same time.After21 days of drug intervention,fasting blood glucose,serum sex hormones and insulin levels of rats in each group were detected and the insulin resistance index was calculated.(3)The morphological changes of ovarian tissues of rats in each group were observed,the expression of Kisspeptin in the arcuate nucleus of the three groups were observed by immunohistochemical staining,the level of KISSm RNA in the hypothalamus of the three groups were detected by Fluorescence Immunohybridization.Results:(1)PCOS rat model was successfully constructed,the estrus cycle was manifested as a continuous interval,the surface of the ovaries was uneven,insulin resistance appeared,testosterone(P<0.05),insulin(P<0.01),serum luteinizing hormone(P<0.001),progesterone and serum follicle-stimulating hormone did not change significantly.(2)The number of Kisspeptin cells(p<0.001)and the expression of KISS1 m RNA(P<0.0001)in the hypothalamic arcuate nucleus of PCOS rats model with continuous gavage structure of letrozole were increased compared with the normal saline group.(3)After 21 days of metformin gavage intervention,the rat’s estrus cycle was restored,serum luteinizing hormone and testosterone decreased,serum follicle-stimulating hormone and progesterone did not change significantly,and the insulin resistance index decreased.(4)The PCOS rats in the metformin intervention group showed that cystic follicles were reduced,granular cells were arranged neatly and thickened and follicles and corpus luteum were developed normally.(5)The expression levels of Kisspeptin(P<0.001)and KISS1 m RNA(P<0.0001)in PCOS rats that feeded with metformin were lower than in the letrozole group.Conclusions: Our results show that letrozole has a significant effect to the expression of Kisspeptin in the arcuate nucleus of the hypothalamus in PCOS rats.Metformin can improve reproductive and metabolic disorders in PCOS rats by reducing the expression of Kisspeptin.Kisspeptin may be a new target for the treatment of PCOS in the future. |
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