Evaluation of the interaction effect of low-dose estrogen on morphine-induced ovarian polycystic in rats

Polycystic ovary syndrome (PCOS) is a relatively common problem among women of reproductive age. Morphine can disrupt the reproductive axis and cause ovarian cysts. Estrogen can reduce the incidence of benign cysts and ovarian cancer. We investigated the interfering effect of low-dose estrogen on morphine-induced PCOS in rats. Female Wistar rats (weighing 200 to 250 g) were purchased from Pasteur Institute of Iran and adapted to standard conditions in an animal care center. In the diestrous phase, they were randomly divided into four groups: single morphine (5 mg/kg), alone estrogen (0.03, 0. 06 and 0.09 mg/kg), estrogen + morphine, and control (saline, 1 mL/kg). Seventy-two h after injection (i.p.), blood samples were taken from animals under anesthesia to analyze serum factors. After surgery, the uteri and ovaries were examined biometrically, then collected in formalin and examined. Statistical analysis was performed by analysis of variance (ANOVA). The ovaries of morphine-treated rats showed polycystic feature, however, the number of cysts was significantly reduced in the presence of estrogen (especially at a very low dose of 0.03 mg/kg). Morphine also reduced LH level, which was improved by co-injection of low-dose estrogen (0.03 mg/kg). Administration of estrogen in low doses may have a protective effect on morphine-induced PCOS in rat.