Comparison Of Polycystic Ovary Syndrome Rat Models Induced By Letrozole And Dehydroepiandrosterone

Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine disorder disease among the women of childbearing ages. The incidency rate accounts for 5%-10% among the infertility women and 75%-80% among the anovulatory women, it threatens a large number of women's health seriously. It is a highly heterogeneous disease, the pathophysiology and clinical manifestations of the disease are diverse, but the pathogenesis is unclear. The typical clinical manifestations include menstrual abnormalities, polycystic ovary, obesity, infertility, hairy, acne, etc, it is often accompanied by hyperlipemia and insulin resistance. The change of pathophysiology involved heredity, endocrine, sugar metabolism, lipid metabolism, protein metabolism and ovarian local control factors, it is the hotspot and difficulty in the endocrine department of gynaecology.PCOS patients often suffere with long-term complications such as diabetes mellitus, cardiovascular disease and endometrial cancer. It affectes the patient's quality of life and mental health seriously and brought negative impact on social and family harmony.At present, the treatment of the disease is mainly medical treatment, hardly take surgery treatment. Collecting clinical samples to study the pathogenesis of the disease and treatment is very difficult, so establishing a suitable rat model is extremely important for researching the etiology, Pathogenesis, clinical diagnosis and treatment strategies of PCOS. There are many methods of building PCOS animal models, most have the characteristics of polycystic ovary. But these models imitate one or a few aspects of the pathological characteristic PCOS, some models are even incompatible with PCOS pathologic features, these model can not well applied to clinical research. This study use letrozole irrigation stomach method and DHEA injection subcutaneously to establish PCOS rat models, according to the endocrine characteristic of PCOS, evaluate the two kinds of rat models from the rat weight, ovarian morphology, the volume and relative quality of ovarian, ovarian histological change, estrous cycle changes, the hormones level and the receptor proteins expressed on ovary respectively, providing experimental basis for the research of PCOS.ObjectiveThe study established two kinds of PCOS rat models induced by letrozole and dehydroepiandrosterone, and evaluated models from eight aspects, such as the weight of rat, ovarian morphology, ovarian volume and relative quality, ovarian estrogen histological, rats estrogen cycle, sex hormone level and specific receptor protein expressed ovarian and so on.,in order to choose the appropriate model of rats for study the clinical disease.Materials and Methods1 Study ObjectCleaning level female SD rats aged six weeks and 23 days each sixty cases were divided into experimental group, experimental control group and blank control group randomly. They were administered letrozole and DHEA respectively to induce PCOS rat model.2 Methods2.1 Feeding conditionRaised in cleaning environment, at 20-24℃temperature,40%-60% humidity, ten hours sunlight everyday, free to water and diet pellet.2.2 Letrozole induced modelsExperimental groups of 20 rats that were administered letrozole at concentrations of lmg/kg dissolved in 1% CMC p.o. once daily, experimental control group of 20 rats that received vehicle only (1% aqueous solution of Carboxymethyl cellulose [CMC]) once daily, it lasted both 21 days, the last group of 20 rats as blank group given nothing.2.3 DHEA induced modelsExperimental group of 20 rats that were administered DHEA dissolved in glycerol at concentrations of 6 mg/100g body weight,dissolved in 0.2ml glycerol once daily, experimental control group of 20 rats were given 0.2ml glycerol each for 21 days, the blank group given nothing.2.4 The observed indexes of modelsMental state of rats were monitored daily, vaginal smear and dyeing, in order to judge oestrous cycles, weighted rats every three days and drawed the curve graph of rats ponderal growth.2.5 Collection and disposal of samplesAt the 21th day, all rats were anaesthetized by aether, blood were extracted from heart quickly, serum was stored at -20℃, weighed the two ovaries and measured the length(A), width(B) and hight(C), one ovary was fixed in 10% formaldehyde, another ovary was flushed with PBS then stored at -80℃.2.6 Detection Indexes2.6.1 The volume and relative quality of ovaryAccording the computational formula V=0.52×A×B×C calculated the volume of ovaries, calculated relative quality of ovary as the quality of ovary/the weight of rat×10-3.2.6.2 The histology of ovaryParaffin embedded the maximal plane of ovary and cut into slices in 4μm thickness, then HE dyed.2.6.3 Serum sex hormonesThe indexes of LH,FSH,E2,P and T as the were measured by radio-immunity analysis.2.6.4 receptor proteins in OvarianThe expression of AR and LHR located in rat ovary were measure by immunohistochemistry SP method, the relative quantity of AR and LHR expressed in rat ovary were assayed by Western blot.3 Statistical treatmentSPSS 16.0 was used for studies. All data were calculated using mean±SD. The mean of each group was compared by homogeneity of variance test and Independent sample t-test. Comparing data by one-way ANOVA and LSD method within the group there was a statistical significance when P<0.05.Results1 General condition of rats:all rats were in good condition, bodyhair smooth and reaction sensitive.2 The change in weight and oestrous cycle of rats:①the increased weight oflelrozol experimental group were exceeded than controls obviously (P<0.05), the experimental group lost regular oestrous cycle after the twelfth day;②The increased weight of DHEA experimental group had no statistical differences with controls (P> 0.05), oestrous cycle of DHEA experimental group were in chaos; They did not lose regular oestrous cycle wholly until the end of experiment;③The control groups keep regular oestrous cycle.3 The morphology, histology, volume and relative quality change of ovary:①The ovary of lelrozol experimental group looked pale, envelop thickened and many cystic follicles; histology showed granular cell were reduced to 2-3 layers, interstitial cell proliferated, oocyte and corpus luteum were disappeared mostly, the volume and relative quality of experimental ovary were both larger than controls (P<0.05).②The ovary of DHEA experimental group looks pale, envelop thickened and cystic follicles were not obvious; histology showed granular cell were reduced, interstitial cell proliferated, the volume of experimental ovaries were smaller than controls (P< 0.05), but there were no Statistical differences with the relative quality of ovaries among three groups;③The ovary of control group appeared ruddy and smooth, granular cell reached 8-9 layers.4 The change of sex hormone:①The concentration of LH,T and LH/FSH of lelrozol experimental group were higher than two controls significantly, while FSH,P,E2 were Lower than the controls obviously (P<0.05);②the indexes of DHEA experimental group T,E2 were higher than two controls significantly, FSH were lower than two controls (P<0.05), there were no statistical differences among there group with LH,P and LH/FSH (P>0.05)5 The specific protein expression of ovary:①Lelrozol experimental group had higher expression of AR and LHR than controls significantly (P<0.05),②DHEA experimental group had higher expression of AR than controls significantly (P< 0.05), there were no statistical differences among three groups with LHR (P>0.05)ConclusionsThe PCOS rats models induced by Lelrozol were more approximate to clinical disease than DHEA models.