Chronic, low concentration exposure to pharmaceuticals impacts multiple organ systems in zebrafish

Abstract

Pharmaceuticals are found in both receiving and drinking water due to their persistent release in waste-water effluents, raising concerns for environmental and human health. Chronic, aqueous exposure of zebrafish (Danio rerio) to environmentally relevant concentrations of acetaminophen (ACE), venlafaxaine (VEN) (10μgL−1), carbamazepine (CBZ) and gemfibrozil (GEM) (0.5 and 10μgL−1) decreased reproductive output. Atretic oocytes and altered ovarian histology were seen in female zebrafish exposed to CBZ and GEM, suggesting a direct effect on oocyte development that may account for the reduced fecundity. Apoptosis within the theca and granulosa cells was identified in exposed female zebrafish with atretic oocytes by TUNEL positive staining. The incidence of follicular apoptosis was nearly 2-fold higher in exposed females than the controls. All compounds significantly altered kidney proximal tubule morphology but there was no difference in the incidence of apoptotic cells within the kidney between control and exposed in either males or females. Liver histology was altered by ACE and GEM exposure. Parental exposure to pharmaceuticals did not increase developmental abnormalities, hatching success, or mortality in embryos. Yet, direct exposure of embryos to ACE increased developmental abnormalities and mortality; exposure to 0.5μgL−1 of all pharmaceuticals increased mortality. CBZ decreased plasma 11-ketotestosterone concentrations in males and females. Overall, these data suggest that low concentration, chronic exposure of fish to pharmaceuticals impacts fish development as well as multiple organ systems in adult fish, leading to effects on reproduction and histology of liver and kidney. These results are significant in understanding the consequences of chronic, low concentration pharmaceutical exposure to fish and suggest that exposed populations are at risk of negative impacts to reproduction and health.