Reproductive effects of oestrogenic endocrine disrupting chemicals in Astyanax rivularis inhabiting headwaters of the Velhas River, Brazil

The Velhas River is themost polluted river in the state of Minas Gerais, south- eastern Brazil. Due to its historical and environmental relevance, the aim of this study was to evaluate the effects of oestrogenic endocrine disruptors on the reproduction of the lambari Astyanax rivularis, a small- sized species found in headwaters of the Sao Francisco River basin. Quarterly field samplings were carried out during a reproductive cycle in three streams of the upper Velhas River: S1 (reference site) and S2 and S3 (sites contaminated by untreated sewage). Themain oestrogenic compoundswere evaluated in water using HPLC/MS. Molecular, histological and reproductive biomarkerswere assessed in liver and gonad. The results showed higher average concentrations of oestradiol (> 200 ng/l) in S2 and S3, oestrone (> 250 ng/l) in S2 aswell as oestriol (> 200 ng/l), bisphenol A (> 190 ng/l), and nonylphenol (>600 ng/l) in S3 compared to S1 (<70 ng/l for all compounds). In S2 and S3, there was an increase in the proportion of females, higher ELISA levels of vitellogenin (Vtg) and proteins of the zona radiata (Zrp) in liver males. Insulin- like growth factor (IGF- I) levels were lower in S2 males, which also had a smaller body size, a smaller seminiferous tubule diameter, a higher proportion of spermatogonia, and lower proportion of spermatozoa in relation to S1. Histopathological analyses detected an increase in yolk deficient oocytes and over- ripening in the contaminated sites, and these alterationswere associated to a reduction of hepatic Vtg levels and a delay in spawning, respectively. Intersex specimens with perinucleolar follicles in amultifocal distribution in the testis were detected in S2 and S3. These results indicate that chronic exposure to oestrogenic compounds induced endocrine disruption that may affect wild populations of A. rivularis in the Velhas River. (C) 2017 Elsevier B.V. All rights reserved.