Chronic exposure to iron oxide nanoparticles (γ-Fe2O3) induces gonadal histopathology on male guppies (Poecilia reticulata)

Abstract

The iron oxide nanoparticles (IONPs) have been widely applied to nanomedicine, biology, and nanoremediation. However, its ecotoxicological effects in aquatic organisms remain unclear. The guppy (Poecilia reticulata) is a suitable model to assess the ecotoxicity, reproductive toxicity, and environmental risk of emergent pollutants, such as nanoparticles (NPs). In this study, the effects of citrate-functionalized maghemite (γ-Fe2O3) NPs on reproductive behavior and spermatogenesis of guppies were investigated over 21 days of exposure. Male guppies were exposed to maghemite NPs at environmentally relevant concentrations (0.3 and 3.0 μg L−1) for 14 and 21 days, jointly with a control group (reconstituted water). The reproductive toxicity was analyzed in terms of biometric parameters, sexual behavior, and gonadal histopathology (qualitative and histomorphometric analyzes following by histopathological indices). Results indicated that the chronic exposure to maghemite NPs did not affect male reproductive behavior, but changed the spermatogenesis (increased the spermatid S1 and decreased the spermatocytes and spermatozeugmata frequency). The maghemite NPs induced histopathological damages associated with inflammatory responses and regressive alterations in the testis of guppies. The IONPs can lead to reproductive impairment in freshwater fish, indicating its potential environmental risk.