Integrated biological response to environmentally-relevant concentration of amitriptyline in Sparus aurata

•Environmentally relevant concentration of AMI cause a toxic effect on S. aurata.•Lysosomal responses are especially sensitive to AMI exposure.•The biological responses induced by AMI are not accumulation dependent.•The effects of AMI on biomarkers in aquatic organisms need further research.•Lysosomal biomarkers can apply successfully in S. aurata. Amitriptyline (AMI) is a commonly tricyclic antidepressant to treat depression, anxiety, and other conditions. Like many other pharmaceuticals, AMI and its by-products are incompletely removed during wastewater treatment and therefore they are released to rivers, estuaries and coastal waters. The presence of this kind of compounds in the water environment may involve a negative impact on non-target aquatic organisms at relatively low concentrations. However, the knowledge of AMI effects on aquatic organisms in the environment is scarce. Thus, the objective of this work is to determine the effects of environmentally-relevant concentrations of AMI on biological responses at biochemical and cellular levels in marine teleost. Gilt-head seabream (S. aurata) were exposed to AMI for 7 days at 0.2 μg/L in an open flow system and a battery of biomarkers were investigated: acetylcholinesterase, catalase, superoxide dismutase, glutathione S-transferase, cytochrome C oxidase, P450 CYP1A1 ethoxyresorufin (O) dealkylation, and lysosomal biomarkers. Biomarkers were integrated as IBR/n (biological response index). Overall, it can be concluded that AMI exposure at environmentally-relevant concentration induces significant biological responses to stress in marine teleost, especially in lysosomal biomarkers. However, further research is needed about the effects of AMI and other pharmaceuticals on biomarkers in non-targeted species, to raise the knowledge about the toxicity of this type of emerging pollutants.