The impact of nano-polypropylene accumulation in the brain on behavioral changes in Zebrafish (Danio rerio)

Abstract

Plastic pollution in the environment has emerged as a new contaminant with potential toxicological impacts on various organisms. Among them, nanoplastics pose a great threat to the ecosystem because they are small in size, have high bioavailability, and exist anywhere in the environment. While extensive research is currently underway to understand the toxicity of nanoplastic, our comprehension remains limited, primarily due to the constraints of standardized toxicity studies using polymers of specific sizes and types. To address these gaps, this study conducted toxicity experiments using directly synthesized polypropylene nano particles (PPNPs). The accumulation of PPNPs in the brain was confirmed, and the neurotoxic effects of accumulated PPNPs were investigated. Zebrafish (Danio rerio) were chosen as the experimental model due to their genetic and biological similarity to humans and comparable physiological characteristics with other animal models. Zebrafish exposed to four concentrations of PPNPs under optimal rearing conditions were used for analysis. The selected concentrations are control, 10, 100, and 1000 μg/L, and 10 μg/L and 100 μg/L reflect the plastic concentration in the environment. The presence of PPNPs in the zebrafish brain was confirmed through pyrolysis gas chromatography-mass spectrometry and bio-transmission electron microscope. Behavioral monitoring assessed mobility and aggression, while enzyme neurotransmitters and neural activity levels were measured. The accumulation of PPNPs in the brain, verified by TEM micrography, led to neurotoxicity, resulting in reduced mobility and aggressiveness. Changes in neurotransmitter levels and neural activity, associated with behavior further supported these findings. In conclusion, this study suggests that environmental plastic pollution can induce neurotoxicity in organisms, and emphasizes the need for appropriate management of these materials.