RESUMO
Some heavy metals related to human activities were measured in the water of Chascomús lake. The maximum concentrations were: 0.23⯵g/L for Cd, 4.28⯵g/L for Cr, 22.09⯵g/L for Cu, 2.49⯵g/L for Ni, 3.24⯵g/L for Pb and 210.76⯵g/L for Zn. The values of Cd, Cr, Cr, Pb and Zn were above the Argentine National Guidelines for the Protection of the Aquatic life. The analysis of gonadal condition of pejerrey fish (Odontesthes bonariensis) from this lake did not revealed any reproductive damages. However, exposures with environmental concentrations of Cd, Cr, Cu and Zn under laboratory conditions of pejerrey males (14â¯days), caused a significant increase of the expression of the three variants of gnrh in the brain (within Cd exposure) and a decrease in cyp19a1b mRNA (within Cu exposure). Furthermore, at pituitary level, a decrease in fshb transcript levels was observed in the fish exposed to Cd and Cr and a decrease in the expression of both gonadotropin receptors at gonadal level in Zn exposure. Moreover, the gonads of the fish exposed to all the tested metals suffered structural damages showing shortness of the spermatic lobules, fibrosis, testis ova and the presence of piknotic cells. All these findings alert that heavy metals pollution affects the expression of key reproductive genes and gonadal structure of fish species that represent the predominant group of organisms and are considered sentinel species in the aquatic ecosystems.
Assuntos
Sistema Endócrino/metabolismo , Monitoramento Ambiental , Peixes/metabolismo , Lagos/química , Metais Pesados/toxicidade , Reprodução , Poluentes Químicos da Água/toxicidade , Animais , Apoptose/efeitos dos fármacos , Sistema Endócrino/efeitos dos fármacos , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Peixes/sangue , Masculino , Metais Pesados/análise , Antígeno Nuclear de Célula em Proliferação/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Testículo/efeitos dos fármacos , Testículo/metabolismo , Testículo/patologia , Testosterona/sangue , Poluentes Químicos da Água/análiseRESUMO
The aim of the present study was to assess the responses of the gonopodium morphology and the gonadal and liver histology of adult male Cnesterodon decemmaculatus to sublethal long-term exposure concentrations of 17α-ethinylestradiol (EE2). Two experiments were conducted exposing the fish to waterborne concentrations of EE2 ranging from 20 ng/L to 200 ng/L for 8 wk, 12 wk, and 16 wk. Intersex gonads were observed after 8 wk and 16 wk in fish exposed to 200 ng EE2/L and 100 ng EE2/L, respectively. Oocytes' development from testis germ cells and replacement of the efferent duct periodic acid-Schiff-positive secretion surrounding spermatozeugmata by parenchymal tissue and duct structure alterations were the major observed changes in the gonads. In contrast, no response was observed in the gonopodium morphology. Liver histology was also altered, showing increasing steatosis, single-cell necrosis to generalized necrosis, and disruption of acinar organization from 100 ng EE2/L to 200 ng EE2/L. In summary, the present results showed that although EE2 was not able to alter the morphology of a developed gonopodium, it was capable of inducing development of testicular oocytes in adult male C. decemmaculatus at environmentally relevant concentrations. Thus, externally normal but intersex C. decemmaculatus males would be expected in the wastewater-receiving streams that the species inhabits. According to the literature, the present study would be the first indicating estrogen-induced intersex in adult male poeciliid. Environ Toxicol Chem 2017;36:1738-1745. © 2016 SETAC.