Polystyrene nanoplastics disrupt glucose metabolism and cortisol levels with a possible link to behavioural changes in larval zebrafish

Nadja R Brun,Anna-Pavlina G Haramis,Martina G Vijver,Suzanne C Vink,Christian Tudorache,Patrick Van Hage,Marcel J M Schaaf,Ellard R Hunting

doi:10.1038/s42003-019-0629-6

Nadja R Brun, Anna-Pavlina G Haramis + Show 6 more

Open Access

https://doi.org/10.1038/s42003-019-0629-6

Copy DOI

Abstract

Plastic nanoparticles originating from weathering plastic waste are emerging contaminants in aquatic environments, with unknown modes of action in aquatic organisms. Recent studies suggest that internalised nanoplastics may disrupt processes related to energy metabolism. Such disruption can be crucial for organisms during development and may ultimately lead to changes in behaviour. Here, we investigated the link between polystyrene nanoplastic (PSNP)-induced signalling events and behavioural changes. Larval zebrafish exhibited PSNP accumulation in the pancreas, which coincided with a decreased glucose level. By using hyperglycemic and glucocorticoid receptor (Gr) mutant larvae, we demonstrate that the PSNP-induced disruption in glucose homoeostasis coincided with increased cortisol secretion and hyperactivity in challenge phases. Our work sheds new light on a potential mechanism underlying nanoplastics toxicity in fish, suggesting that the adverse effect of PSNPs are at least in part mediated by Gr activation in response to disrupted glucose homeostasis, ultimately leading to aberrant locomotor activity.

Highlights

Plastic nanoparticles originating from weathering plastic waste are emerging contaminants in aquatic environments, with unknown modes of action in aquatic organisms
Given the direct involvement of cortisol in increased activity[30], we have subsequently examined behavioural changes by measuring distance moved during alternating light–dark cycles as a common behavioural trigger in fish using wild-type, hyperglycemic, and gr mutant larvae exposed to polystyrene nanoplastic (PSNP)
Insulin staining, marking the pancreatic islet, showed that PSNP exposure leads to a significant reduction of the size of the insulin expression domain (Fig. 3b, Supplementary Fig. 2; t(12) = 2.65, p = 0.0212). These findings suggest that bioaccumulated PSNPs may affect glucose metabolism

Summary

Introduction

Plastic nanoparticles originating from weathering plastic waste are emerging contaminants in aquatic environments, with unknown modes of action in aquatic organisms. Recent studies suggest that internalised nanoplastics may disrupt processes related to energy metabolism Such disruption can be crucial for organisms during development and may lead to changes in behaviour. Our work sheds new light on a potential mechanism underlying nanoplastics toxicity in fish, suggesting that the adverse effect of PSNPs are at least in part mediated by Gr activation in response to disrupted glucose homeostasis, leading to aberrant locomotor activity. There remain considerable knowledge gaps in the mode of action of nanoplastics and the potential consequences at higher functional and organisational biological levels Such knowledge is essential to allow for monitoring and predicting the consequences of the anticipated buildup of nanoplastics for the environment. The mechanistic underpinning of these PSNP-induced behavioural changes in fish remains to a large extent elusive, but can potentially be tied to neurological or metabolic effects. Coping with stress results in different patterns in both serotonergic activity[20] and cortisol[21] as part of a complex set of feedback interactions between the hypothalamus, the pituitary gland, and interrenal tissues (HPI-axis)

Methods

Results

Conclusion