Effects of Thyroxine on the Male and Female Reproductive Functions in the Model of Experimental Hypothyroidism

Abstract

Background and Aim: In hypothyroidism, thyroxine is used as a therapeutic agent generally. According to recent data, thyroxin induced testicular dysfunction and abnormal contractions of the uterus caused by abnormal muscle tone of the uterine smooth muscle were observed in pregnant women treated with thyroxine, an epidemiological survey of the two cohort studies showed that the rate of cesarean section in pregnant women with hypothyroidism was two times higher. Thus, thyroxine plays an important role in the treatment of the hypothyroidism, but there are also negative aspects. Therefore, the study of thyroxine treatment in the model of the hypothyroidism is useful in the treatment of male infertility and pregnancy complications. Methods: White mice with 20-22 g and Wistar rats with 120-160 g were used as experimental animals. Mice were fed normal food with dibazol aqueous solution (50 μg/10 g/day) for 90 days to evaluate the effect of thyroxine on the gonads. In the study group L-thyroxine (0.5 μg/10 g/day) was fed for 40 days from 51st day of dibazol aqueous solution application. In the control group, medication was not given. After drug application, ratio of the testes and epididymis weight on the whole body weight, sperm count, sperm motility, the ratio of ovarian weight to body weight, follicle count were evaluated. Female rats were fed normal food with dibazol aqueous solution (0.5 mg/100 g/day) for 90 days to evaluate the effect of thyroxine on the uterus. In the study group L-thyroxine (5 μg/100 g/day) was fed for 40 days from 51st day of dibazol aqueous solution application. In the control group medication was not received. After drug application, threshold, duration and maximum amplitude in the evoked EMG were evaluated by M-24 type 2 channel EMG. Results: In the hypothyroidism model, thyroxine therapy resulted in testicular dysfunction, but not ovarian dysfunction. And in the hypothyroidism model, thyroxine therapy reduced the threshold for evoked EMG and prolonged the duration of the evoked EGM in the uterine muscles.