Effects of exposure to micro/nanoplastics of polystyrene on neuronal oxidative stress, neuroinflammation, and anxiety-like behavior in mice: A Systematic Review

Polystyrene is a polymer widely used across various industrial and commercial sectors. Upon degradation, it fragments into microplastics (MP) and nanoplastics (NP), whose accumulation in the environment raises significant ecological and health concerns. These particles can disrupt digestive, reproductive, and other functions in exposed organisms. In this systematic review, the effects of mice exposure to PS-NP or PS-MP (PS-MP/NP) were systematically examined, focusing on neuronal oxidative stress, neuroinflammation , and anxiety-like behavior. Three databases (PubMed, Web of Science, and Scopus) were searched without any time filters until July 20, 2024. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Two independent reviewers assessed the quality of studies using the Systematic Review Centre for Laboratory Animal Experimentation tool (SYRCLE). A total of 24 original articles were included of 332 citations. Articles were published between 2021 and 2024. Out of the studies reviewed, 12 used PS-NP, 10 used PS-MP, and two used both PS-NP and PS-MP separately. The particle sizes ranged from 0.023 to 50 μm, with the majority exhibiting a spherical shape. Seven studies reported results that the exposure to PS-MP/NP elevated reactive oxygen species (ROS) levels, and/or increased lipid peroxidation-Malondialdehyde (LPO-MDA), and/or decreased antioxidants, especially superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Eight studies demonstrated an increase in neuroinflammation markers, including TNF-α, IL-1β, IL-6, GFAP, and Iba1. Regarding anxiety-like behavior, 10 studies confirmed its induction. Furthermore, maternal exposure induced neurotoxic responses in offspring. Overall, exposure to PS-MP/NP induced oxidative stress, neuroinflammation, and anxiety-like behavior in mice. These results highlighted complex interactions between PS-MP/NP and the nervous system, emphasizing the need for a more thorough exploration of involved mechanisms.