LETROZOLE AND FRUCTOSE-INDUCED POLYCYSTIC OVARIES IN THE RAT: A NOVEL MODEL EXHIBITING BOTH OVARIAN AND METABOLIC CHARACTERISTICS FOR POLYCYSTIC OVARY SYNDROME IN RAT

Introduction: There are numerous animal models available for polycystic ovary syndrome (PCOS), a fully convincing model for PCOS reflecting all pathologic condition of PCOS seen in humans is not available due to difficulties in inducing all pathologies in rat models. If so, it will help to test drug to treat PCOS. The main goal of this study is to create a new model to reflect all pathologic conditions of PCOS seen in humans using non-steroidal aromatase inhibitor letrozole and fructose in rats. Methods: Twelve rats were divided into two groups containing 6 rats each. Vehicle control group rats received 1% aqueous solution of carboxmethlycellulose (CMC) once daily orally for 28 days and PCOS group was administered letrozole at a concentration of 1 mg/kg dissolved in 1% CMC p.o. once daily for 28 days. Along with these rats were allowed free access of 10% fructose solution daily. During experimental period, vaginal smears were collected daily for estrus cycle determination. Rats were sacrificed and blood sample were collected for hormonal and other biochemical assays. Ovaries were removed to proceed with histolopathological study. Results: When compared to vehicle control group, ovaries from PCOS group showed high incidence of ovarian cyst with incomplete luteinization and decreased number of corpus lutea.  Although serum estradiol and progesterone levels were reduced, testosterone levels were elevated, as were levels of luteinizing hormone (LH). Serum follicle-stimulating hormone (FSH) levels were markedly increased in the PCOS group. The PCOS group rats showed significant increase in insulin resistance with compensatory significant hyperinsulinemia than the vehicle control group. Conclusions: Our study was completely fulfilling and convincing as in human PCOS, this rat model is fully convincing for studying PCOS and in several ways, it is similar to the human PCOS.