A Mixture of Persistent Organic Pollutants and Perfluorooctanesulfonic Acid Induces Similar Behavioural Responses, but Different Gene Expression Profiles in Zebrafish Larvae.

Abdolrahman Khezri,Erik Ropstad,Thomas Fraser,Karin Zimmer,Rasoul Nourizadeh-Lillabadi,Jorke Kamstra,Vidar Berg

doi:10.3390/ijms18020291

Abstract

Persistent organic pollutants (POPs) are widespread in the environment and some may be neurotoxic. As we are exposed to complex mixtures of POPs, we aimed to investigate how a POP mixture based on Scandinavian human blood data affects behaviour and neurodevelopment during early life in zebrafish. Embryos/larvae were exposed to a series of sub-lethal doses and behaviour was examined at 96 h post fertilization (hpf). In order to determine the sensitivity window to the POP mixture, exposure models of 6 to 48 and 48 to 96 hpf were used. The expression of genes related to neurological development was also assessed. Results indicate that the POP mixture increases the swimming speed of larval zebrafish following exposure between 48 to 96 hpf. This behavioural effect was associated with the perfluorinated compounds, and more specifically with perfluorooctanesulfonic acid (PFOS). The expression of genes related to the stress response, GABAergic, dopaminergic, histaminergic, serotoninergic, cholinergic systems and neuronal maintenance, were altered. However, there was little overlap in those genes that were significantly altered by the POP mixture and PFOS. Our findings show that the POP mixture and PFOS can have a similar effect on behaviour, yet alter the expression of genes relevant to neurological development differently.

Highlights

Persistent organic pollutants (POPs) refers to groups of toxic environmental chemicals with a carbon-based structure, resistant to environmental degradation and widely distributed via soil, water and air [1]
Regarding the increase in swimming speed, we found that 48–96 hpf is the sensitive window for the total POP mixture and perfluorooctanesulfonic acid (PFOS) exposure, as exposures before 48 hpf had no effect on swimming speed
We aimed to assess the possible neurobehavioural toxicity of an environmentally relevant mixture of persistent organic pollutants (POPs), which was constructed based on Scandinavian human blood data

Summary

Introduction

Persistent organic pollutants (POPs) refers to groups of toxic environmental chemicals with a carbon-based structure, resistant to environmental degradation and widely distributed via soil, water and air [1]. Because of their lipophilic nature, POPs tend to bioaccumulate in top predators and humans [2]. As for the potential mechanisms, work in zebrafish has demonstrated that POPs such as PFOS can promote cell death in the brain following early life exposure which is associated with altered behaviour [20]. Behavioural responses may be related to dopaminergic deficits [27]

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