Melatonin Protects the Histologic Structure of the Uterus in Conditions of Zearalenone Intake

BACKGROUND: Zearalenone is a widely spread mycotoxin, contaminant of most cereal grains. It has uterotropic, estrogenic and anabolic activity in farm animals. The results are hormonal disbalances as hyperestrogenism, Zearalenone inhibits follicle-stimulating hormone production, thus supressing ovarian follicle development and ovulation. Also, it induces oxidative stress. Melatonin acts as a potent natural antioxidant and regulates the reproductive function by modification of steroidogenesis. OBJECTIVE: The present study was conducted to provide detailed qualitative histological analysis of uterus of female rats treated with zearalenone and melatonin and contribute to better understanding of the topic. METHODS: Forty adult, female Wistar rats were equally divided into five groups: Z group – zearalenone, 0,3 mg/kg, i.g.; M group – melatonin, 10 mg/kg, i.p.; ZM group –concomitant application of zearalenone and melatonin in the same dosing regimen, VZ group–zearalenone vehiculum/sunflower oil, i.g. and MZ group–melatonin vehiculum/5% ethanol in Ringer, i.p. Animals were treated daily for 28 consecutive days. After that period, all animals were sacrificed to obtain samples for qualitative histological analysis using the light microscope. RESULTS: Zearalenone led to the alterations of the uterine structures, predominantly in the endometrium that were characterized by metaplasia and hypertrophy of the epithelial cells and hypercellularity of the stroma. In the myometrium, zearalenone induced hypertrophy and hyperplasia of the myocytes. CONCLUSION: Melatonin, when applied together with zearalenone, blocked the adverse effects of the zearalenone.