Metabolic and immune impairments induced by the endocrine disruptors benzo[a]pyrene and triclosan in Xenopus tropicalis

Abstract

Despite numerous studies suggesting that amphibians are highly sensitive to cumulative anthropogenic stresses, the role played by endocrine disruptors (EDs) in the decline of amphibian populations remains unclear. EDs have been extensively studied in adult amphibians for their capacity to disturb reproduction by interfering with the sexual hormone axis.Here, we studied the in vivo responses of Xenopus tropicalis males exposed to environmentally relevant concentrations of each ED, benzo[a]pyrene (BaP) and triclosan (TCS) alone (10 μg L−1) or a mixture of the two (10 μg L−1 each) over a 24 h exposure period by following the modulation of the transcription of key genes involved in metabolic, sexual and immunity processes and the cellular changes in liver, spleen and testis. BaP, TCS and the mixture of the two all induced a marked metabolic disorder in the liver highlighted by insulin resistance-like and non-alcoholic fatty liver disease (NAFLD)-like phenotypes together with hepatotoxicity due to the impairment of lipid metabolism. For TCS and the mixture, these metabolic disorders were concomitant with modulation of innate immunity. These results confirmed that in addition to the reproductive effects induced by EDs in amphibians, metabolic disorders and immune system disruption should also be considered.