Influência de potenciais desreguladores endócrinos sobre as respostas moleculares e fisiológicas de Crenuchus spilurus (Günther, 1863)

Abstract

The adverse effects of endocrine-disrupting chemicals (EDCs) on aquatic organisms and human health represent a current problem and worldwide public concern. The increased availability of the element selenium and the recurrent episodes of low oxygen concentration in Amazon waters (hypoxia) have been considered factors of concern due to their potential impacts as EDCs in aquatic ecosystems. Yet, the effects of these stressors on the endocrine disruption of Amazonian fish species are still poorly known. The present study sought to evaluate the effect of hypoxia exposure and environmentally relevant concentrations of selenium (0µg L-1, 10µg L-1, 100µg L-1), as well the combination of both, on males and females of Crenuchus spilurus for 28 days. Important reproductive parameters were evaluated, such as mRNA expression of estrogen receptor regulatory genes and eventual gonadal morphological changes, as well as the selenium bioaccumulation in the gills and liver at different oxygen concentrations. The gene expression results were correlated with bioaccumulation in liver tissue, the proportion of germ cells and gonadal histopathology of females and males of C. spilurus. The results showed an increase in the incidence of histopathologies and changes in the morphology and the number of germ cells in both sexes, especially in males, which presented the occurrence of intersex in their gonads, both in selenium and hypoxia treatments, as well as their combination. In addition, the expression profiles of genes related to steroidogenesis in brains (ERα, ER2α, ER2β) of males and females showed changes after exposure to selenium and hypoxia. Our results demonstrated that these stressors have significantly affected the reproductive biology in both sexes by damaging the structure of the gonads, altering the gene expressions related to the endocrine system in the hypothalamic-pituitary axis and consequently causing changes in the levels of steroid hormones. These findings provide new insights into the effects of selenium and hypoxia on endocrine disruption C. spilurus, suggesting harmful consequences for the reproductive biology of this species, with emphasis on future investigations of its potential risks in the aquatic environment.