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

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.

Polystyrene nanoplastics accumulate in ZFL cell lysosomes and in zebrafish larvae after acute exposure, inducing a synergistic immune response in vitro without affecting larval survival in vivo

“…6 Differences with published data could also be attributed to the use of other ZF strains (e.g. AB/TL wild type as in van Pomeren et al, 48 Veneman et al, 10 Brun et al 7 or Sökmen et al 11 ), instead of wild type larvae as in our case. We decided to use wild type zebrafish (no strain) to approach the individual variability present in a natural population, in order to better emulate an environmental situation.…”

“…This pattern of accumulation has been previously reported although with some differences, likely due to the specific exposure time, dose, size and larvae age. For example, Brun et al observed accumulation of 25 nm PS-NPs (20 mg l −1 ) 7,8 in the intestine, exocrine pancreas and gall bladder after 48 h of exposure at 120 hpf (5 dpf). It is worth mentioning that there is a considerable variation in between studies, with PS-NPs being located in the intestine and neuromast, 7 in the heart region, 10 in the digestive track and eyes, 48 in the gut and gills region 49 and in the gastrointestinal tract, gallbladder, liver, pancreas, heart and brain.…”

“…oxidative stress, complement system or glucose metabolism). Alterations in behaviour, measured by a decrease 6 or increase 7 in locomotor activity, changes in glucose metabolism and cortisol levels, 7 intestinal and skin damage triggering a pro-inflammatory response 8 and production of oxidative stress and lipid accumulation, 9 have been documented in zebrafish after waterborne exposure to PS-NPs. Other studies have evaluated the effects of direct injection of PS-NPs on zebrafish embryos, describing changes in the transcriptome 10 or production of reactive oxygen species (ROS) and apoptosis.…”

Toxicity of Microplastics and Nanoplastics in Mammalian Systems

“…For the gut, pathological manifestations of MP/NP toxicity include documented changes in gut biomarkers related to epithelial barrier integrity, inflammation, and oxidative stress [83,86], as well as changes in gut microbiota [82,83,86]. In the case of liver, changes in metabolites, key metabolic enzymes, and oxidative stress-induced enzymes occur [49,74,79,81,85,87]. MPs/NPs could be internalized [88], and then cause detectable biomarker changes in blood cells [47,88,89].…”

Glucocorticoid receptor activities in the zebrafish model: a review

“…Other applications of this line are listed in Fig. 4, which covers a considerable number of different physiological processes and underlies the value of the zebrafish model (Kwan et al 2016, Brun et al 2019, Mosser et al 2019, Palstra et al 2019, Sireeni et al 2020.…”