The Neurobiology of Social Context-Dependent Stress Responses

Project Information

NotSOSTRESSED

Grant agreement ID: 101029339

DOI

10.3030/101029339

Project closed

EC signature date 13 April 2021

Start date 1 September 2021

End date 13 October 2025

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 170 585,60

EU contribution

€ 170 585,60

Coordinated by

KATHOLIEKE UNIVERSITEIT LEUVEN
Belgium

Periodic Reporting for period 1 - NotSOSTRESSED (The Neurobiology of Social Context-Dependent Stress Responses )

Reporting period: 2021-09-01 to 2023-08-31

Summary of the context and overall objectives of the project

Millions of tons of plastics are released into the environment every year. Polystyrene (PS) is one of the top five plastic polluters of the environment, being used for, amongst others, packaging and disposable consumables. Environmental abiotic factors degrade the plastic waste into micro- and nanoplastics (MNP), which consequently exponentially accumulate into the environment. As a result, humans and ecological systems are constantly exposed to MNPs trough ingestion, water and air. In recent years, the ubiquitous environmental presence and hazards of MNPs have been extensively reported, posing significant risks for species health and ecotoxicity. The impact of MNP on biological systems have been documented in various species and modelorganisms. In rodents, studies have shown detrimental toxicity effects of MNPs on various organs e.g. the gut, lungs, liver and the reproductive and CNS (reviewed in Wang et al., Environ. Int., 2024). However, despite emerging research on MNP and health and fitness, our understanding of the MNP ingestion toxicity consequences are limited. Thus far, to the best of our knowledge, studies on the impact of MNPs on social behaviour and CNS genetic alterations have not been conducted. The modelorganism Drosophila melanogaster has become an ecotoxicological model for safety assessment of MNPs and nanoparticles. Due to their smaller size then MPs, NPs (<1 µm) are expected to behave differently to MPs and disperse deeper into tissues, therefor inducing differential health and fitness outcomes in comparison to MPs. In this study, we identified the functional consequences of polystyrene nanoplastics (PS-NP) on social behaviour, locomotion and CNS gene expression. The main objectives of this study were:

• WP1: Determine the impact of PS-NP on Drosophila male and female social behaviour
• WP2: Analyse locomotion consequences of PS-NP exposure in male and female fruitflies
• WP3: Sex dimorphic genetic profiling of the central brain after PS-NP treatment

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

After exposure to 100 nm PS-NP [500 µm/ml] during the adult stage, Drosophila males showed an significant increase in locomotion behaviour as measured by distance travelled (calculated per 5 min bins) and walking percentage in comparison to wildtype males that were kept on standard flyfood (SF) throughout developmental and adult stages (Figure 1 A&C). Surprisingly, during adult stage PS-NP [500 µm/ml] treated males had significantly fewer inter-male interactions than compared to wildtype SF males (Figure 1 E). However, both locomotion and social behavioural phenotypes are not present in males that were exposed to PS-NP [500 µm/ml] during development only or throughout all stages (Figure 1 A, C & E). In contrast, females that were fed PS-NP [500 µm/ml] during adult stages displayed an opposing locomotion phenotype compared to males, with a significant decrease in distance travelled and walking percentage (Figure 1 B&D). In addition, females treated throughout with PS-NP showed significant lower distance travelled. Similar to males, PS-NP treated females had fewer interactions with female conspecifics than their wildtype counterpart. However, this trend was only significant in developmentally and throughout exposed flies, but not during adult stage treated flies.
In conclusion, males and female flies show sex dimorphic locomotion effects after PS-NP treatment, with males and females showing opposing significant locomotion phenotypes after acute treatment with Polystyrene. The opposing locomotion effect in males and females argues in favour of CNS directed locomotion phenotypes after PS-NP ingestion. At the time of writing the report the data of the 100 µm /ml exposure data still needs to analysed.
The project’s results will be published as Versteven et al., 2026.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

• General study of NP exposure consequences as studies about NP impacting (human) health and ecological systems are limited
• Influence of PS-NP exposure on male and female Drosophila social behaviour (this was not known until this study) (WP1)
• Sex-dimorphic effects of PS-NP ingestion on the fruitfly’s locomotion behaviour
• Influence of PS-NP administration on Drosophila male and female CNS genetic processes (in progress): The RNAseq data will be available after the deadline of the technical report (WP3)
• Technological: state-of-the-art custom-made behavioural set-up including Raspberry Pi technology and custom-designed Python scripts (WP1&2)