Soy isoflavones exert beneficial effects on letrozole-induced rat polycystic ovary syndrome (PCOS) model through anti-androgenic mechanism

Context: Soy is the main source of phytoestrogens, which has long been used as traditional food. One major subtype of phytoestrogens includes isoflavones and they are scientifically validated for their beneficial actions on many hormone-dependent conditions. Objective: The present study examines the effect of soy isoflavones on letrozole-induced polycystic ovary syndrome (PCOS) rat model. Materials and methods: PCOS was induced in Sprague-Dawley rats with of 1mg/kg letrozole, p.o. once daily for 21 consecutive days. Soy isoflavones (50 and 100mg/kg) was administered for 14 days after PCOS induction. Physical parameters (body weight, oestrous cycle determination, ovary and uterus weight) metabolic parameters (oral glucose tolerance test, total cholesterol), steroidal hormone profile (testosterone and 17b-oestradiol), steroidogenic enzymes (3b-hydroxy steroid dehydrogenase (HSD) and 17b-HSD), oxidative stress and histopathology of ovary were studied. Results: Soy isoflavones (100mg/kg) treatment significantly altered the letrozole-induced PCOS symptoms as observed by decreased body weight gain (p< 0.05), percentage diestrous phase (p< 0.001), testosterone (p< 0.001), 3 beta-HSD (p< 0.01) and 17 beta-HSD (p< 0.001) enzyme activity and oxidative stress. Histological results reveal that soy isoflavones treatment in PCOS rats resulted in well-developed antral follicles and normal granulosa cell layer in rat ovary. Discussion: Treatment with soy isoflavones exerts beneficial effects in PCOS rats (with decreased aromatase activity) which might be due to their ability to decrease testosterone concentration in the peripheral blood. Conclusion: Analysis of physical, biochemical and histological evidences shows that soy isoflavones may be beneficial in PCOS.