Lycopene againsts the polystyrene microplastics-induced neurotoxicity via modulation of mTOR/Beclin-1 activities in adult male Wistar rats

Abstract

Polystyrene microplastics (PS-MPs) pose a significant threat to aquatic ecosystems, causing neuronal toxicity in aquatic species, and Lycopene (LYC), a neuroprotective substance, could potentially mitigate this issue. This study examined the neurotherapeutic benefit of lycopene on the neurochemical status of rats affected by PS-MPs. Twenty Wistar rats were divided into four groups of five rats each: a vehicle group, a PS-MPs treatment group, a PS-MPs + LYC co-treatment group, and an LYC supplementation group. The experiment lasted 56 days, and all substances were administered orally. Neuronal toxicity was evaluated using oxidative stress/neurochemical biomarkers. Lipid peroxidation (LPO), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) were measured as indicators of oxidative stress. Nitric Oxide (NO), gamma-aminobutyric acid (GABA), hydroxyl radical ( • OH), ammonia, and glutamate levels were assessed to evaluate neurotransmitter balance. Cathepsin marker enzyme activity was also measured to assess lysosomal function. PS-MPs-treated animals showed increased LPO, NO, • OH, Bcl-2 interacting protein 1 (Beclin-1), ammonia, glutamate, and reduced GABA, Mammalian targets of rapamycin (mTOR), and antioxidant activity in their cerebral cortex. The combination of PS-MPs and Lycopene treatment improved GABA, cathepsin marker enzyme activity, and brain structure, restoring normal neuronal bodies, oval nuclei, and cerebral cortex. Lycopene ameliorated oxidative stress deficits, decreased LPO, NO, • OH, ammonia, and glutamate levels, and restored antioxidant enzyme activity. In conclusion, the findings suggest a potential link between PS-MPs and cognitive dysfunction through neurochemical alterations, while the administration of lycopene mitigated the neurochemical changes brought on by PS-MPs.