The Establishment Of The Letrozole-induced Model Of Polycystic Ovary Syndrome In Rats And The Influence Of Pioglitazone Hydrochloride To The Expression Of Lep R On The Ovaries And Hypothalamus Of The Rats With Polycystic Ovary Syndrome

【Object】To evaluate the significance of the PCOS rat model which induced by letrozole and to analyse the relationship between Lep R and polysystic ovary syndrome.To do research on the influence of pioglitazone hydrochloride to the expression of Lep R on the ovaries and hypothalamus of the rats with polysystic ovary syndrome【Method】Thirty female SD rats were divided into three groups: normal control group , PCOS group and pioglitazone hydrochloride treated group.Serum T, LH,FG ,INS, LEP level were measured. The relative expression of Lep R on the ovaries and hypothalamus of each group was detected by methods of immunohistochemistry and Real Time RT PCR .【Results】1. The PCOS rat model which induced by letrozole showed similar endocrine features with human PCOS. They are hyperinsulinemia and high serum leptin level. 2. The rats'serum T,LH,INS,LEP levels decreased statistically significant after treated by pioglitazone hydrochlorid (P <0.05). Correlation analysis showed that T have a positive correlation with Homa-IR, insulin(rs=0.443,0.366;P <0.05). 3. It shows that the expression of Lep R on the hypothalamus of the PCOS Group is weaker than that of the normal control group(P <0.05), but it was enhanced by pioglitazone hydrochlorid (P <0.05).The expression of Lep R on the ovaries of PCOS group is more than that of the normal control group(P <0.05), but it becomes weaker after the intervention of pioglitazone hydrochlorid (P <0.05).【Conclusion】1. The PCOS rat model which induced by Letrozole is a suitable model for researching the pathogenesis of PCOS,especially the mechanisms of insulin resistance and leptin resistance. 2. The reduction of the Lep R expression on the hypothalamus of polycystic ovarian syndrome rats lead to leptin resistance, which may be the main cause that lead to no ovulation, menstrual disorders and other major endocrine disorders in PCOS. When the expression of Lep R on the ovaries of PCOS rats become stronger, the inhibitory action of leptin on ovarian secretion of estrogen and pregnancy hormone increased.This may be the cause of anovulation and reducing fertility in PCOS rats. 3. Insulin sensitizing agents-pioglitazone hydrochlorid not only can improve the hyperinsulinemia, high serum leptin levels,high androgenic hormones of the PCOS rats,but also enhance the expression of Lep R on hypothalamus ,which obviously ease the leptin resistance,and decrease the expression of Lep R on ovaries which weaken the depressant effect of leptin to ovaries'function which can secrete estrogenic hormone and pregnancy hormone.