RESUMO
The aim of this study was to investigate the possible effects of melatonin on rat uterine tissue against exposure with bisphenol A (BPA) in the neonatal period. Twenty-four female rats were divided into four groups, (n=6) per group. Group I was used as a control (sesame oil + ethanol), group II was injected daily with (100 mg/kg) BPA by subcutaneously (sc) daily postnatal days (PND 0-10), group III was injected daily with (10 mg/kg) melatonin by sc for 10 days (PND 20-30), and group IV was injected daily with (100 mg/kg) BPA (PND 0-10) and (10 mg/kg) melatonin (PND 20-30). All rats were sacrificed in the same day of metestrus cycle, approximately PND 70. Histological analyses, immunostaining of B cell lymphoma 2 (Bcl-2), and cytochrome c and TUNEL assays were performed. According to our results, neonatal exposure to BPA accelerates onset of puberty, causes degenerative and morphometric changes on rat uterus, and increases apoptotic reaction rates. The immunoreactivity of Bcl-2 was decreased after BPA administration. In addition, immunoreactivity of Bcl-2 showed an increase after melatonin treatment. However, cytochrome c immunoreactivity was decreased after melatonin administration. Our results suggest that melatonin may have positive effects against BPA-induced degenerative changes on rat uterus.